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51a44bb7326bdb5126ef70c6b184cebd7049e1d2 | wikidoc | Tattoo | Tattoo
A tattoo is a permanent marking made by inserting ink into the layers of skin to change the pigment for decorative or other reasons. Tattoos on humans are a type of decorative body modification, while tattoos on animals are most commonly used for identification or branding.
Tattooing has been practiced worldwide. The Ainu, the indigenous people of Japan, traditionally wore facial tattoos. Today one can find Berbers of Tamazgha and Maori of New Zealand with facial tattoos. Tattooing was widespread among Polynesian peoples and among certain tribal groups in the Philippines, Borneo, Mentawai Islands, Africa, North America, South America, Mesoamerica, Europe, Japan, Cambodia, New Zealand and China. Despite some taboos surrounding tattooing, the art continues to be popular in many parts of the world.
# Etymology
The word "tattoo" is a borrowing of the Samoan word tatau, meaning to mark or strike twice (the latter referring to traditional methods of applying the designs). The first syllable "ta", meaning "hand", is repeated twice as an onomatopoeic reference to the repetitive nature of the action, and the final syllable "U" translates to "color". The instrument used to pierce the skin in Polynesian tattooing is called a hahau, the syllable "ha" meaning to "strike or pierce".
The OED gives the etymology of tattoo as "In 18th c. tattaow, tattow. From Polynesian (Tahitian, Samoan, Tongan, etc.) tatau. In Marquesan, tatu." The first closest known usage of the word in English was recorded in the diary of Captain James Cook in 1769 during his voyage to the Marquesas Islands. The text reads, “...they print signs on people’s body and call this tattaw”, referring to the Polynesian customs. Sailors on the voyage later introduced both the word and reintroduced the concept of tattooing to Europe.
In Japanese the most common word used for traditional designs is, "Horimono".
The traditional Japanese hand method is called, "Tebori".
The word, "Irezumi," simply means, "insertion of ink," and could mean tattoos using Tebori, or Western style machine, (Or for that matter, any method of tattoing using insertion of ink).
Japanese may use the word, "Tattoo," to mean non-Japanese styles.
Tattoo enthusiasts may refer to tattoos as, "Tats," "Ink," "Art," or, "Work," and to tattooists as, "Artists". The latter usage is gaining greater support, with mainstream art galleries holding exhibitions of both traditional and custom tattoo designs. Copyrighted tattoo designs that are mass-produced and sold to tattoo artists are known as flash, a notable instance of industrial design. Flash sheets are prominently displayed in many tattoo parlors for the purpose of providing both inspiration and ready-made tattoo images to customers.
# History
Tattooing has been a Eurasian practice at least since Neolithic times. Ötzi the Iceman, dating from the fourth to fifth millennium BC, was found in the Ötz valley in the Alps and had approximately 57 carbon tattoos consisting of simple dots and lines on his lower spine, behind his left knee, and on his right ankle. Other mummies bearing tattoos and dating from the end of the second millennium BC have been discovered at Pazyryk on the Ukok Plateau. Tattooing in Japan is thought to go back to the Paleolithic era, some ten thousand years ago. Various other cultures have had their own tattoo traditions, ranging from rubbing cuts and other wounds with ashes, to hand-pricking the skin to insert dyes.
Tattoos are created by inserting colored materials inside the skin's surface. The first tattoos probably were created by an accident. Someone had a small wound, and rubbed it with soot and ashes from a fire. Once the wound had healed, they saw that a mark stayed permanently.
# Styles
native, religios, wildlife & nature, orintal, symbols, old school, fantasy, portraits
# Purposes
## Decorative and spiritual uses
Tattoos have served as rites of passage, marks of status and rank, symbols of religious and spiritual devotion, decorations for bravery, sexual lures and marks of fertility, pledges of love, punishment, amulets and talismans, protection, and as the marks of outcasts, slaves and convicts. The symbolism and impact of tattoos varies in different places and cultures, sometimes with unintended consequences. Also, tattoos show how a person feels about another person, or how they feel about a relative, preferably mother/father or daughter/son.
Today, people choose to be tattooed for cosmetic, sentimental/memorial, religious, and magical reasons, and to symbolize their belonging to or identification with particular groups, including criminal gangs (see criminal tattoos) but also a particular ethnic group or law-abiding subculture. Some Māori still choose to wear intricate moko on their faces. In Laos, Cambodia, and Thailand, the yantra tattoo is used for protection against evil and to increase luck.
## Identification
People have also been forcibly tattooed for various reasons. The best known example is the ka-tzetnik identification system for Jews in part of the concentration camps during the Holocaust. However, tattoos can be linked with identification in more positive ways. For example, in the period of early contact between Māori and Europeans, Māori chiefs sometimes drew their moko (facial tattoo) on documents in place of a signature. Even today, tattoos are sometimes used by forensic pathologists to help them identify burned, putrefied, or mutilated bodies. Tattoo pigment is buried deep enough in the skin that even severe burns will often not destroy a tattoo. Because of this, many members of today's military will have their identification tags tattooed onto their ribs; these are known as "meat tags".
Tattoos are also placed on animals, though very rarely for decorative reasons. Pets, show animals, thoroughbred horses and livestock are sometimes tattooed with identification and other marks.
Pet dogs and cats are often tattooed with a serial number (usually in the ear, or on the inner thigh) via which their owners can be identified. Also, animals are occasionally tattooed to prevent sunburn (on the nose, for example). Such tattoos are often performed by a veterinarian and in most cases the animals are anesthetized during the process. Branding is used for similar reasons and is often performed without anesthesia, but is different from tattooing as no ink or dye is inserted during the process.
## Cosmetic
When used as a form of cosmetics, tattooing includes permanent makeup, and hiding or neutralizing skin discolorations. Permanent makeup are tattoos that enhance eyebrows, lips (liner and/or lipstick), eyes (liner), and even moles, usually with natural colors as the designs are intended to resemble makeup.
## Medical
Medical tattoos are used to ensure instruments are properly located for repeated application of radiotherapy and for the areola in some forms of breast reconstruction. Tattooing has also been used to convey medical information about the wearer.
# Prevalence
Tattoos have experienced a resurgence in popularity in many parts of the world, particularly in North America, Japan, and Europe. The growth in tattoo culture has seen an influx of new artists into the industry, many of whom have technical and fine art training. Coupled with advancements in tattoo pigments and the on going refinement of the equipment used for tattooing, this has led to an improvement in the quality of tattoos being produced.
During the 2000s, the presence of tattoos became evident within pop culture, inspiring television shows such as A&E's Inked and TLC's Miami Ink & LA Ink (Tattoo Tv). The decoration of blues singer Janis Joplin with a wristlet and a small heart on her left breast, by the San Francisco tattoo artist Lyle Tuttle, is taken as a seminal moment in the popular acceptance of tattoos as art. As seen in the 2007 movie Eastern Promises, body art again features heavily, showcasing the ink-embroidered torso of a Russian Mobster. Tattoos are generally considered an important part of the culture of the Russian Mafia - see ].
In many traditional cultures tattooing has also enjoyed a resurgence, partially in deference to cultural heritage. Historically, a decline in traditional tribal tattooing in Europe occurred with the spread of Christianity. However, some Christian groups, such as the Knights of St. John of Malta, sported tattoos to show their alligence. A decline often occurred in other cultures following European efforts to convert aboriginal and indigenous people to Western religious and cultural practices that held tattooing to be a "pagan" or "heathen" activity. Within some traditional indigenous cultures, tattooing takes place within the context of a rite of passage between adolescence and adulthood.
A poll conducted online in July 2003 estimated that 16% of all adults in the United States have at least one tattoo. The highest incidence of tattoos was found among the gay, lesbian and bisexual population (31%) and among Americans ages 25 to 29 years (36%) and 30 to 39 years (28%). Regionally, people living in the West (20%) were more likely to have tattoos. Democrats were more likely to have tattoos (18%) than Republicans (14%) and Independents (12%); approximately equal percentages of males (16%) and females (15%) have tattoos.In the fall of 2006, a study was completed by the Journal of the American Academy of Dermatology. It found that 24% of Americans who were between the ages of 18 and 50 had a tattoo, which is almost, one in four people in the United states. Also, in a 1990's article put out by U.S. News & World Report, tattooing, was ranked as the sixth fastest growing retail venture of the 1990s, establishing the tattoo industry as a hot property.However,as of 2008 there is some evidence that the Fashion for tattooing in the Western World may have peaked.
# Negative associations
In Japan, tattoos are strongly associated with the Yakuza, particularly full body tattoos done the traditional Japanese way ("Tebori"). Certain public Japanese bathhouses (sentō) and gymnasiums often openly ban those bearing large or graphic tattoos in an attempt to prevent Yakuza from entering.
In the United States many prisoners and criminal gangs use distinctive tattoos to indicate facts about their criminal behavior, prison sentences, and organizational affiliation.
"Tear tattoos," for example, can be symbolic of murder, with each tear representing a death of a friend. Insofar as this cultural or subculture use of tattoos predates the widespread popularity of tattoos in the general population, tattoos are still associated with criminality. At the same time, members of the U.S. military have an equally well established and longstanding history of tattooing to indicate military units, battles, kills, etc., an association which remains widespread among older Americans. Tattooing is also common in the British Armed Forces.
Tattoos can have additional negative associations for women; Although derogatory slang phrases are sometimes used to describe a tattoo on a woman's lower back, it remains one of the most popular spots for a tattoo for females. The prevalence of women in the tattoo industry itself, along with larger numbers of women wearing tattoos, has changed negative perceptions.
A study of "at-risk" (as defined by school absenteeism and truancy) adolescent girls showed a positive correlation between body-modification and negative feelings towards the body and self-esteem.
Leviticus 19:28 is often used to oppose tattoos. This biblical law is strictly adhered to by observant Jews.
# Mechanism
Tattooing involves the placement of pigment into the skin's dermis, the layer of connective tissue underlying the epidermis. After initial injection, pigment is dispersed throughout a homogenized damaged layer down through the epidermis and upper dermis, in both of which the presence of foreign material activates the immune system's phagocytes to engulf the pigment particles. As healing proceeds, the damaged epidermis flakes away (eliminating surface pigment) while deeper in the skin granulation tissue forms, which is later converted to connective tissue by collagen growth. This mends the upper dermis, where pigment remains trapped within fibroblasts, ultimately concentrating in a layer just below the dermis/epidermis boundary. Its presence there is very stable, but in the long term (decades) the pigment tends to migrate deeper into the dermis, accounting for the degraded detail of old tattoos.
# Procedure
Some tribal cultures traditionally created tattoos by cutting designs into the skin and rubbing the resulting wound with ink, ashes or other agents; some cultures continue this practice, which may be an adjunct to scarification. Some cultures create tattooed marks by hand-tapping the ink into the skin using sharpened sticks or animal bones or, in modern times, needles. Traditional Japanese tattoos (Horimono) are still "hand-poked," that is, the ink is inserted beneath the skin using non-electrical, hand-made and hand held tools with needles of sharpened bamboo or steel. This method is known as "Tebori".
The most common method of tattooing in modern times is the electric tattoo machine, which inserts ink into the skin via a group of needles that are soldered onto a bar, which is attached to an oscillating unit. The unit rapidly and repeatedly drives the needles in and out of the skin, usually 80 to 150 times a second. This modern procedure is ordinarily sanitary. The needles are single-use needles that come packaged individually. The tattoo artist must wash not only his or her hands, but they must also wash the area that will be tattooed. Gloves must be worn at all times and the wound must be wiped frequently with a wet disposable towel of some kind.
Prices for this service vary widely globally and locally, depending on the complexity of the tattoo, the skill and expertise of the artist, the attitude of the customer, the costs of running a business, the economics of supply and demand, etc. The time it takes to get a tattoo is in proportion with its size and complexity. A small one of simple design might take fifteen minutes, whereas an elaborate sleeve tattoo or back piece requires multiple sessions of several hours each.
The modern electric tattoo machine is far removed from the machine invented by Samuel O'Reilly in 1891. O'Reilly's machine was based on the rotary technology of the electric engraving device invented by Thomas Edison. Modern tattoo machines use electromagnetic coils. The first coil machine was patented by Thomas Riley in London, 1891 using a single coil. The first twin coil machine, the predecessor of the modern configuration, was invented by another Englishman, Alfred Charles South of London, in 1899.
## "Stick and poke"
A technique often used for home-made tattoos is "stick and poke": The tip of a sewing needle is wrapped in ink-soaked thread, leaving only the point protruding, and keeping this simple instrument saturated with ink as the skin is pricked over and over, creating a design. The purpose of the thread is to keep the point of the needle coated in ink, increasing the quantity of ink that penetrates the skin. Inks can be improvised from a number of sources such as coal, ashes or shoe polish, but Higgins "Black Magic" waterproof ink is the brand most commonly cited by collectors of so called "India ink" or "stick and poke" tattoos in the US today. Sometimes called "prison tattoos" these tattoos are also popular with gutterpunks, and others associated with the modern hobo subculture, who frequently tattoo visible parts of their bodies, including their hands and faces.
## "Natural" tattoos
According to George Orwell, coal miners could develop characteristic tattoos owing to coal dust getting into wounds. This can also occur with substances like gunpowder. Similarly, a traumatic tattoo occurs when a substance such as asphalt is rubbed into a wound as the result of some kind of accident or trauma. These are particularly difficult to remove as they tend to be spread across several different layers of skin, and scarring or permanent discoloration is almost unavoidable depending on the location. In addition, tattooing of the gingiva from implantation of amalgam particles during dental filling placement and removal is possible and not uncommon. A common example of such accidental tattoos is the result of a deliberate or accidental stabbing with a pencil or pen, leaving graphite or ink beneath the skin.
See Scarification
## Dyes and pigments
Early tattoo inks were obtained directly from nature and were extremely limited in pigment variety. Today, an almost unlimited number of colors and shades of tattoo ink are mass-produced and sold to parlors worldwide. Tattoo artists commonly mix these inks to create their own, unique pigments.
A wide range of dyes and pigments can be used in tattoos, from inorganic materials like titanium dioxide and iron oxides to carbon black, azo dyes, and acridine, quinoline, phthalocyanine and naphthol derivates, dyes made from ash, and other mixtures. The current trend for tattoo pigment favors Acrylonitrile butadiene styrene (ABS plastic) as seen by the widespread popularity of Intenze, Millennium and other ABS pigmented brands.
Iron oxide pigments are used in greater extent in cosmetic tattooing. Many pigments were found to be used in a surveyTemplate:Ref label of professional tattooists. Recently, a blacklight-reactive tattoo ink using PMMA microcapsules has surfaced. The technical name is BIOMETRIX System-1000, and is marketed under the name "Chameleon Tattoo Ink". This same ink can also be found as "The Original Blacklight Inks by NEWWEST Technologies".
## Studio hygiene
The properly equipped tattoo studio will use biohazard containers for objects that have come into contact with blood or bodily fluids, sharps containers for old needles, and an autoclave for sterilizing tools. Certain jurisdictions also require studios by law to have a sink in the work area supplied with both hot and cold water.
Proper hygiene requires a body modification artist to wash his or her hands before starting to prepare a client for the stencil, between clients, and at any other time where cross contamination can occur. The use of single use disposable gloves is also mandatory. In some states and countries it is illegal to tattoo a minor even with parental consent, and it is usually not allowed to tattoo impaired persons, people with contraindicated skin conditions, those who are pregnant or nursing, those incapable of consent due to mental incapacity or those under the influence of alcohol or drugs.
Before the tattooing begins the client is asked to approve the final position of the applied stencil. After approval is given the artist will open new, sterile needle packages in front of the client, and always use new, sterile or sterile disposable instruments and supplies, and fresh ink for each session (loaded into disposable ink caps which are discarded after each client). Also, all areas which may be touched with contaminated gloves will be wrapped in clear plastic to prevent cross-contamination. Equipment that cannot be autoclaved (such as counter tops, machines, and furniture) will be wiped with an approved disinfectant.
Membership in professional organizations, or certificates of appreciation/achievement, generally helps artists to be aware of the latest trends. However, many of the most notable tattooists do not belong to any association. While specific requirements to become a tattooist vary between jurisdictions, many mandate only formal training in bloodborne pathogens, and cross contamination. The local department of health regulates tattoo studios in many jurisdictions.
For example, according to the health department in Oregon and Hawaii, tattoo artists in these states are required to take and pass a test ascertaining their knowledge of health and safety precautions, as well as the current state regulations. Performing a tattoo in Oregon state without a proper and current license or in an unlicensed facility is considered a felony offense. Tattooing was legalized in New York City, Massachusetts, and Oklahoma between 2002 and 2006.
## Aftercare
Tattoo artists, and people with tattoos, vary widely in their preferred methods of caring for new tattoos. Some artists recommend keeping a new tattoo wrapped for the first twenty-four hours, while others suggest removing temporary bandaging after two hours or less. Many tattooists advise against allowing too much contact with hot tub or pool water, or soaking in a tub for the first two weeks. This is to prevent the tattoo ink from washing out or fading due to over-hydration and avoid infection from exposure to bacteria and chlorine. In contrast, other artists suggest that a new tattoo be bathed in very hot water early and often.
General consensus for care advises against removing the scab that forms on a new tattoo, and avoiding exposing one's tattoo to the sun for extended periods; both of these can contribute to fading of the image. Furthermore, it is agreed that a new tattoo needs to be kept clean. Various products may be recommended for application to the skin, ranging from those intended for the treatment of cuts, burns and scrapes, to cocoa butter, lanolin, A&D or Aquaphor. Oil based ointments are almost always recommended to be used in very thin layers due to their inability to evaporate and therefore over-hydrate the already perforated skin. In recent years, specific commercial products have been developed for tattoo aftercare. Although opinions about these products vary, there is near total agreement that either alone or in addition to some other product, soap and warm water work well to keep a tattoo clean and free from infection.Template:Ref labelHowever, salt water can cause a fresh wound to sting as well as leave it vulnerable to infections and fading.
Ultimately, the amount of ink that remains in the skin throughout the healing process determines, in large part, how robust the final tattoo will look. If a tattoo becomes infected (uncommon but possible if one neglects to properly clean their tattoo) or if the scab falls off too soon (e.g., if it absorbs too much water and sloughs off early or is picked or scraped off), then the ink will not be properly fixed in the skin and the final image will be negatively affected.
## Tattoo removal
While tattoos are considered permanent, it is possible to remove them. Complete removal, however, may not be possible (although many doctors and laser practitioners make the claim that upwards of 95% removal is possible with the newest lasers, especially with black and darker colored inks), and the expense and pain of removing them typically will be greater than the expense and pain of applying them. Some jurisdictions will pay for the voluntary removal of gang tattoos. Gangs will often involuntarily remove gang tattoos, from a person who leaves the gang. Pre-laser tattoo removal methods include dermabrasion, salabrasion (scrubbing the skin with salt), cryosurgery, and excision which is sometimes still used along with skin grafts for larger tattoos.
Tattoo removal is most commonly performed using lasers that react with the ink in the tattoo, and break it down. The broken-down ink is then absorbed by the body, mimicking the natural fading that time or sun exposure would create. This technique often requires many repeated visits to remove even a small tattoo, and may result in permanent scarring. The newer Q-switched lasers are said by the National Institute of Health to result in scarring only rarely, however, and are usually used only after a topical anesthetic has been applied. The NIH recognizes five types of tattoo; amateur, professional, cosmetic, medical, and traumatic (or natural). Areas with thin skin will be more likely to scar than thicker-skinned areas. There are several types of Q-switched lasers, and each is effective at removing a different range of the color spectrum. This laser effectively removes black, blue, purple and red tattoo pigment. New lasers like the Versapulse & Medlite laser treat these colors & yellow and green ink pigment, typically the hardest colors to remove. Black is the easiest color to remove.
Also worth considering is the fact that some of the pigments used (especially Yellow #7) are known to break down into toxic chemicals in the body when attacked by light. This is especially a concern if these tattoos are exposed to UV light or laser removal; the resulting degradation products end up migrating to the kidneys and liver. Laser removal of traumatic tattoos may similarly be complicated depending on the substance of the pigmenting material. In one reported instance, the use of a laser resulted in the ignition of embedded particles of firework debris.
Some wearers opt to cover an unwanted tattoo with a new tattoo. This is commonly known as a cover-up. An artfully done cover-up may render the old tattoo completely invisible, though this will depend largely on the size, style, colors and techniques used on the old tattoo. Some shops and artists use laser removal machines to break down and lighten undesired tattoos to make coverage with a new tattoo easier. Since tattoo ink is translucent, covering up a previous tattoo necessitates darker tones in the new tattoo to effectively hide the older, unwanted piece.
# Records
The current record for the most studio tattoos in a 24 hour period goes to Oliver Peck of Dallas, TX. Previously, the reality star Katherine Von Drachenberg, also known as Kat Von D, star of the reality TV show "LA Ink" on TLC was the record holder. Her tattoos were of the LA Ink logo while the current record holder's artwork consists of the number thirteen.
# Health risks
Because it requires breaking the skin barrier, tattooing may carry health risks, including infection and allergic reactions. In the United States, for example, the Red Cross prohibits a person who has received a tattoo from donating blood for 12 months (FDA 2000), unless the procedure was done in a state-regulated and licensed studio, using sterile technique.. Not all states have a licensing program, meaning that people who receive tattoos in those states are subject to the 12-month deferral regardless of the hygienic standards of the studio. Similarly, the UK does not provide certification for tattooists, and so there is a six month waiting period without exception.
Modern western tattooers reduce such risks by following universal precautions, working with single-use items, and sterilizing their equipment after each use. Many jurisdictions require that tattooists have bloodborne pathogen training, such as is provided through the Red Cross and OSHA.
## Infection
Since tattoo instruments come in contact with blood and bodily fluids, diseases may be transmitted if the instruments are used on more than one person without being sterilized. However, infection from tattooing in clean and modern tattoo studios employing single-use needles is rare. In amateur tattoos, such as those applied in prisons, however, there is an elevated risk of infection. To address this problem, a program was introduced in Canada as of the summer of 2005 that provides legal tattooing in prisons, both to reduce health risks and to provide inmates with a marketable skill. Inmates were to be trained to staff and operate the tattoo parlors once six of them opened successfully.Template:Ref label
Infections that could be transmitted via the use of unsterilized tattoo equipment include surface infections of the skin, herpes simplex virus, tetanus, staph (Infected Tattoo), fungal infections, some forms of hepatitis, and HIV. No person in the United States is reported to have contracted HIV via a commercially-applied tattooing process. Washington state's OSHA studies have suggested that since the needles used in tattooing are not hollow, in the case of a needle stick injury the amount of fluids transmitted may be small enough that HIV would be difficult to transmit. Tetanus risk is prevented by having an up-to-date tetanus booster prior to being tattooed. The Centers for Disease Control and Prevention states that no data exist in the United States indicating that persons with exposures to tattooing alone are at increased risk for HCV infection. In 2006, the CDC reported 3 clusters with 44 cases of methicillin-resistant staph infection traced to unlicensed tattooists (MMWR 55(24)).
## Allergic reactions
Perhaps due to the mechanism whereby the skin's immune system encapsulates pigment particles in fibrous tissue, tattoo inks have been described as "remarkably nonreactive histologically".
Allergic reactions to tattoo pigments are uncommon except for certain brands of red and green. People who are sensitive or allergic to certain metals may react to pigments in the skin with swelling and/or itching, and/or oozing of clear fluid called serum. Such reactions are quite rare, however, and some artists will recommend performing a test patch.
For those who are allergic to latex, many artists are using non-latex or will use non-latex gloves if asked.
There is also a small risk of anaphylactic shock (hypersensitive reaction) in those who are susceptible, but the chance of a health risk is small.
Due to the fact that laser removal of tattoo ink causes a release of ink into the bloodstream the risk of anaphylactic shock is also present during removal.
## Tattoo inks
Modern tattooing inks are carbon based pigments that have uses outside of commercial tattoo applications. Although the United States Food and Drug Administration technically requires premarket approval of pigments it has not actually approved the use of any ink or pigments for tattooing (because of a lack of resources for such relatively minor responsibilities). As of 2004 the FDA does perform studies to determine if the contents are possibly dangerous, and follow up with legal action if they find them to have disallowed contents, including traces of heavy metals (such as iron oxide) or other carcinogenic materials (see CA lawsuit). The first known study to characterize the composition of these pigments was started in 2005 at Northern Arizona University (Finley-Jones and Wagner). The FDA expects local authorities to legislate and test tattoo pigments and inks made for the use of permanent cosmetics. In California, the state prohibits certain ingredients and pursues companies who fail to notify the consumer of the contents of tattoo pigments. Recently, the state of California sued nine pigment and ink manufacturers, requiring them to more adequately label their products.
Acrylonitrile butadiene styrene (ABS plastic) ground down to an average diameter of slightly less than 1 micrometer is used as the colorant in the brighter tattoo pigments. The tattoo pigments that use ABS result in very vivid tattoos. Many popular brands of tattoo pigment contain ABS as a colorant. ABS colorants produce extremely vivid tattoos that are less likely to fade or blur than the traditional pigments, but ABS tattoo pigment is also harder to remove because it is so much less reactive to lasers.
There has been concern expressed about the interaction between magnetic resonance imaging (MRI) procedures and tattoo pigments, some of which contain trace metals. Allegedly, the magnetic fields produced by MRI machines could interact with these metal particles, potentially causing burns or distortions in the image. The television show MythBusters tested the theory, and found no interaction between tattoo inks and MRI.
However, research by Shellock and Crues reports adverse reactions to MRI and tattoos in a very small number of cases. Wagle and Smith also documented an isolated case of Tattoo-Induced Skin Burn During MR Imaging. The person in the case had a dark, concentrated, loop-shaped tattoo, which the authors speculate could have acted as an RF (radio frequency) pick-up; they also note that this is the first such case they encountered in "thousands of MRI studies". Ratnapalan et al. report another case where an MRI could not be completed due to the patient's extensive tattoos. According to the American Chemical society, homemade tattoos, in which metallic inks have been used in larger quantities, cause these reactions.
Professional tattoists rely primarily on the same pigment base found in cosmetics. Amateurs will often use drawing inks such as Higgins, Pelikan or India ink, but these inks often contain impurities and toxins which can lead to illness or infection. A "green haze" is a telltale sign of a tattoo done with drawing ink.
# Temporary tattoos
Temporary tattoos are popular with models and children as they involve no permanent alteration of the skin but produce a similar appearance that can last anywhere from a few days to several weeks. The most common style is a type of body sticker similar to a decal, which is typically transferred to the skin using water. Although the design is waterproof, it can be removed easily with oil-based creams. Originally inserted as a prize in bubble gum packages, they consisted of a poor quality ink transfer that would easily come off with water or rubbing. Today's vegetable dye temporaries can look extremely realistic and adhere up to 3 weeks due to a layer of glue similar to that found on an adhesive bandage.
Henna tattoos, also known as Mehndi, and silver nitrate stains that appear when exposed to ultraviolet light, can take up to two weeks to fade from the skin. Temporary airbrush tattoos (TATs) are applied by covering the skin with a stencil and spraying the skin with ink. In the past, this form of tattoo only lasted about a week. With the newest inks, tattoos can reasonably last for up to two weeks.
Magician Penn Jillette (of Penn & Teller fame) writes in his book Penn & Teller's How to Play in Traffic that he had a special tattoo made on his arm that used no pigment (the tattoo machine was run without ink). Penn states that the tattoo left a red scar that had a discernible pattern, but would heal to near invisibility after five or six weeks. When filming the remake of Cape Fear, actor Robert De Niro was tattooed with Temptu Ink, a body paint formulated by chemist Samuel Zuckerman. | Tattoo
A tattoo is a permanent marking made by inserting ink into the layers of skin to change the pigment for decorative or other reasons. Tattoos on humans are a type of decorative body modification, while tattoos on animals are most commonly used for identification or branding.
Tattooing has been practiced worldwide. The Ainu, the indigenous people of Japan, traditionally wore facial tattoos. Today one can find Berbers of Tamazgha and Maori of New Zealand with facial tattoos. Tattooing was widespread among Polynesian peoples and among certain tribal groups in the Philippines, Borneo, Mentawai Islands, Africa, North America, South America, Mesoamerica, Europe, Japan, Cambodia, New Zealand and China. Despite some taboos surrounding tattooing, the art continues to be popular in many parts of the world.
# Etymology
The word "tattoo" is a borrowing of the Samoan word tatau, meaning to mark or strike twice (the latter referring to traditional methods of applying the designs).[3] The first syllable "ta", meaning "hand", is repeated twice as an onomatopoeic reference to the repetitive nature of the action, and the final syllable "U" translates to "color".[citation needed] The instrument used to pierce the skin in Polynesian tattooing is called a hahau, the syllable "ha" meaning to "strike or pierce".[citation needed]
The OED gives the etymology of tattoo as "In 18th c. tattaow, tattow. From Polynesian (Tahitian, Samoan, Tongan, etc.) tatau. In Marquesan, tatu." The first closest known usage of the word in English was recorded in the diary of Captain James Cook in 1769 during his voyage to the Marquesas Islands. The text reads, “...they print signs on people’s body and call this tattaw”, referring to the Polynesian customs.[citation needed] Sailors on the voyage later introduced both the word and reintroduced the concept of tattooing to Europe.[4]
In Japanese the most common word used for traditional designs is, "Horimono".
The traditional Japanese hand method is called, "Tebori".
The word, "Irezumi," simply means, "insertion of ink," and could mean tattoos using Tebori, or Western style machine, (Or for that matter, any method of tattoing using insertion of ink).
Japanese may use the word, "Tattoo," to mean non-Japanese styles.
Tattoo enthusiasts may refer to tattoos as, "Tats," "Ink," "Art," or, "Work," and to tattooists as, "Artists". The latter usage is gaining greater support, with mainstream art galleries holding exhibitions of both traditional and custom tattoo designs. Copyrighted tattoo designs that are mass-produced and sold to tattoo artists are known as flash, a notable instance of industrial design. Flash sheets are prominently displayed in many tattoo parlors for the purpose of providing both inspiration and ready-made tattoo images to customers.
# History
Tattooing has been a Eurasian practice at least since Neolithic times. Ötzi the Iceman, dating from the fourth to fifth millennium BC, was found in the Ötz valley in the Alps and had approximately 57 carbon tattoos consisting of simple dots and lines on his lower spine, behind his left knee, and on his right ankle. Other mummies bearing tattoos and dating from the end of the second millennium BC have been discovered at Pazyryk on the Ukok Plateau. Tattooing in Japan is thought to go back to the Paleolithic era, some ten thousand years ago. Various other cultures have had their own tattoo traditions, ranging from rubbing cuts and other wounds with ashes, to hand-pricking the skin to insert dyes.
Tattoos are created by inserting colored materials inside the skin's surface. The first tattoos probably were created by an accident. Someone had a small wound, and rubbed it with soot and ashes from a fire. Once the wound had healed, they saw that a mark stayed permanently.
# Styles
native, religios, wildlife & nature, orintal, symbols, old school, fantasy, portraits
# Purposes
## Decorative and spiritual uses
Tattoos have served as rites of passage, marks of status and rank, symbols of religious and spiritual devotion, decorations for bravery, sexual lures and marks of fertility, pledges of love, punishment, amulets and talismans, protection, and as the marks of outcasts, slaves and convicts. The symbolism and impact of tattoos varies in different places and cultures, sometimes with unintended consequences. Also, tattoos show how a person feels about another person, or how they feel about a relative, preferably mother/father or daughter/son.
Today, people choose to be tattooed for cosmetic, sentimental/memorial, religious, and magical reasons, and to symbolize their belonging to or identification with particular groups, including criminal gangs (see criminal tattoos) but also a particular ethnic group or law-abiding subculture. Some Māori still choose to wear intricate moko on their faces. In Laos, Cambodia, and Thailand, the yantra tattoo is used for protection against evil and to increase luck.
## Identification
People have also been forcibly tattooed for various reasons. The best known example is the ka-tzetnik identification system for Jews in part of the concentration camps during the Holocaust. However, tattoos can be linked with identification in more positive ways. For example, in the period of early contact between Māori and Europeans, Māori chiefs sometimes drew their moko (facial tattoo) on documents in place of a signature. Even today, tattoos are sometimes used by forensic pathologists to help them identify burned, putrefied, or mutilated bodies. Tattoo pigment is buried deep enough in the skin that even severe burns will often not destroy a tattoo. Because of this, many members of today's military will have their identification tags tattooed onto their ribs; these are known as "meat tags".
Tattoos are also placed on animals, though very rarely for decorative reasons. Pets, show animals, thoroughbred horses and livestock are sometimes tattooed with identification and other marks.
Pet dogs and cats are often tattooed with a serial number (usually in the ear, or on the inner thigh) via which their owners can be identified. Also, animals are occasionally tattooed to prevent sunburn (on the nose, for example). Such tattoos are often performed by a veterinarian and in most cases the animals are anesthetized during the process. Branding is used for similar reasons and is often performed without anesthesia, but is different from tattooing as no ink or dye is inserted during the process.
## Cosmetic
When used as a form of cosmetics, tattooing includes permanent makeup, and hiding or neutralizing skin discolorations. Permanent makeup are tattoos that enhance eyebrows, lips (liner and/or lipstick), eyes (liner), and even moles, usually with natural colors as the designs are intended to resemble makeup.
## Medical
Medical tattoos are used to ensure instruments are properly located for repeated application of radiotherapy and for the areola in some forms of breast reconstruction. Tattooing has also been used to convey medical information about the wearer.
# Prevalence
Tattoos have experienced a resurgence in popularity in many parts of the world, particularly in North America, Japan, and Europe. The growth in tattoo culture has seen an influx of new artists into the industry, many of whom have technical and fine art training. Coupled with advancements in tattoo pigments and the on going refinement of the equipment used for tattooing, this has led to an improvement in the quality of tattoos being produced.
During the 2000s, the presence of tattoos became evident within pop culture, inspiring television shows such as A&E's Inked and TLC's Miami Ink & LA Ink (Tattoo Tv). The decoration of blues singer Janis Joplin with a wristlet and a small heart on her left breast, by the San Francisco tattoo artist Lyle Tuttle, is taken as a seminal moment in the popular acceptance of tattoos as art.[1] As seen in the 2007 movie Eastern Promises, body art again features heavily, showcasing the ink-embroidered torso of a Russian Mobster. Tattoos are generally considered an important part of the culture of the Russian Mafia - see [[5]]. [2]
In many traditional cultures tattooing has also enjoyed a resurgence, partially in deference to cultural heritage. Historically, a decline in traditional tribal tattooing in Europe occurred with the spread of Christianity. However, some Christian groups, such as the Knights of St. John of Malta, sported tattoos to show their alligence. A decline often occurred in other cultures following European efforts to convert aboriginal and indigenous people to Western religious and cultural practices that held tattooing to be a "pagan" or "heathen" activity. Within some traditional indigenous cultures, tattooing takes place within the context of a rite of passage between adolescence and adulthood.
A poll conducted online in July 2003 estimated that 16% of all adults in the United States have at least one tattoo. The highest incidence of tattoos was found among the gay, lesbian and bisexual population (31%) and among Americans ages 25 to 29 years (36%) and 30 to 39 years (28%). Regionally, people living in the West (20%) were more likely to have tattoos. Democrats were more likely to have tattoos (18%) than Republicans (14%) and Independents (12%); approximately equal percentages of males (16%) and females (15%) have tattoos.[3]In the fall of 2006, a study was completed by the Journal of the American Academy of Dermatology. It found that 24% of Americans who were between the ages of 18 and 50 had a tattoo, which is almost, one in four people in the United states. Also, in a 1990's article put out by U.S. News & World Report, tattooing, was ranked as the sixth fastest growing retail venture of the 1990s, establishing the tattoo industry as a hot property.However,as of 2008 there is some evidence that the Fashion for tattooing in the Western World may have peaked.[4]
# Negative associations
In Japan, tattoos are strongly associated with the Yakuza, particularly full body tattoos done the traditional Japanese way ("Tebori"). Certain public Japanese bathhouses (sentō) and gymnasiums often openly ban those bearing large or graphic tattoos in an attempt to prevent Yakuza from entering.
In the United States many prisoners and criminal gangs use distinctive tattoos to indicate facts about their criminal behavior, prison sentences, and organizational affiliation.[5]
"Tear tattoos," for example, can be symbolic of murder, with each tear representing a death of a friend. Insofar as this cultural or subculture use of tattoos predates the widespread popularity of tattoos in the general population, tattoos are still associated with criminality. At the same time, members of the U.S. military have an equally well established and longstanding history of tattooing to indicate military units, battles, kills, etc., an association which remains widespread among older Americans. Tattooing is also common in the British Armed Forces.
Tattoos can have additional negative associations for women; Although derogatory slang phrases are sometimes used to describe a tattoo on a woman's lower back, it remains one of the most popular spots for a tattoo for females. The prevalence of women in the tattoo industry itself, along with larger numbers of women wearing tattoos, has changed negative perceptions.
A study of "at-risk" (as defined by school absenteeism and truancy) adolescent girls showed a positive correlation between body-modification and negative feelings towards the body and self-esteem.[6]
Leviticus 19:28 is often used to oppose tattoos. This biblical law is strictly adhered to by observant Jews.
# Mechanism
Tattooing involves the placement of pigment into the skin's dermis, the layer of connective tissue underlying the epidermis. After initial injection, pigment is dispersed throughout a homogenized damaged layer down through the epidermis and upper dermis, in both of which the presence of foreign material activates the immune system's phagocytes to engulf the pigment particles. As healing proceeds, the damaged epidermis flakes away (eliminating surface pigment) while deeper in the skin granulation tissue forms, which is later converted to connective tissue by collagen growth. This mends the upper dermis, where pigment remains trapped within fibroblasts, ultimately concentrating in a layer just below the dermis/epidermis boundary. Its presence there is very stable, but in the long term (decades) the pigment tends to migrate deeper into the dermis, accounting for the degraded detail of old tattoos.[7]
# Procedure
Some tribal cultures traditionally created tattoos by cutting designs into the skin and rubbing the resulting wound with ink, ashes or other agents; some cultures continue this practice, which may be an adjunct to scarification. Some cultures create tattooed marks by hand-tapping the ink into the skin using sharpened sticks or animal bones or, in modern times, needles. Traditional Japanese tattoos (Horimono) are still "hand-poked," that is, the ink is inserted beneath the skin using non-electrical, hand-made and hand held tools with needles of sharpened bamboo or steel. This method is known as "Tebori".
The most common method of tattooing in modern times is the electric tattoo machine, which inserts ink into the skin via a group of needles that are soldered onto a bar, which is attached to an oscillating unit. The unit rapidly and repeatedly drives the needles in and out of the skin, usually 80 to 150 times a second. This modern procedure is ordinarily sanitary. The needles are single-use needles that come packaged individually. The tattoo artist must wash not only his or her hands, but they must also wash the area that will be tattooed. Gloves must be worn at all times and the wound must be wiped frequently with a wet disposable towel of some kind.
Prices for this service vary widely globally and locally, depending on the complexity of the tattoo, the skill and expertise of the artist, the attitude of the customer, the costs of running a business, the economics of supply and demand, etc. The time it takes to get a tattoo is in proportion with its size and complexity. A small one of simple design might take fifteen minutes, whereas an elaborate sleeve tattoo or back piece requires multiple sessions of several hours each.
The modern electric tattoo machine is far removed from the machine invented by Samuel O'Reilly in 1891. O'Reilly's machine was based on the rotary technology of the electric engraving device invented by Thomas Edison. Modern tattoo machines use electromagnetic coils. The first coil machine was patented by Thomas Riley in London, 1891 using a single coil. The first twin coil machine, the predecessor of the modern configuration, was invented by another Englishman, Alfred Charles South of London, in 1899.
## "Stick and poke"
A technique often used for home-made tattoos is "stick and poke": The tip of a sewing needle is wrapped in ink-soaked thread, leaving only the point protruding, and keeping this simple instrument saturated with ink as the skin is pricked over and over, creating a design. The purpose of the thread is to keep the point of the needle coated in ink, increasing the quantity of ink that penetrates the skin. Inks can be improvised from a number of sources such as coal, ashes or shoe polish, but Higgins "Black Magic" waterproof ink is the brand most commonly cited by collectors of so called "India ink" or "stick and poke" tattoos in the US today. Sometimes called "prison tattoos" these tattoos are also popular with gutterpunks, and others associated with the modern hobo subculture, who frequently tattoo visible parts of their bodies, including their hands and faces.
## "Natural" tattoos
According to George Orwell, coal miners could develop characteristic tattoos owing to coal dust getting into wounds. This can also occur with substances like gunpowder. Similarly, a traumatic tattoo occurs when a substance such as asphalt is rubbed into a wound as the result of some kind of accident or trauma. These are particularly difficult to remove as they tend to be spread across several different layers of skin, and scarring or permanent discoloration is almost unavoidable depending on the location. In addition, tattooing of the gingiva from implantation of amalgam particles during dental filling placement and removal is possible and not uncommon. A common example of such accidental tattoos is the result of a deliberate or accidental stabbing with a pencil or pen, leaving graphite or ink beneath the skin.
See Scarification
## Dyes and pigments
Early tattoo inks were obtained directly from nature and were extremely limited in pigment variety. Today, an almost unlimited number of colors and shades of tattoo ink are mass-produced and sold to parlors worldwide. Tattoo artists commonly mix these inks to create their own, unique pigments.
A wide range of dyes and pigments can be used in tattoos, from inorganic materials like titanium dioxide and iron oxides to carbon black, azo dyes, and acridine, quinoline, phthalocyanine and naphthol derivates, dyes made from ash, and other mixtures. The current trend for tattoo pigment favors Acrylonitrile butadiene styrene (ABS plastic) as seen by the widespread popularity of Intenze, Millennium and other ABS pigmented brands.
Iron oxide pigments are used in greater extent in cosmetic tattooing. Many pigments were found to be used in a surveyTemplate:Ref label of professional tattooists. Recently, a blacklight-reactive tattoo ink using PMMA microcapsules has surfaced. The technical name is BIOMETRIX System-1000, and is marketed under the name "Chameleon Tattoo Ink". This same ink can also be found as "The Original Blacklight Inks by NEWWEST Technologies".
## Studio hygiene
The properly equipped tattoo studio will use biohazard containers for objects that have come into contact with blood or bodily fluids, sharps containers for old needles, and an autoclave for sterilizing tools. Certain jurisdictions also require studios by law to have a sink in the work area supplied with both hot and cold water.
Proper hygiene requires a body modification artist to wash his or her hands before starting to prepare a client for the stencil, between clients, and at any other time where cross contamination can occur. The use of single use disposable gloves is also mandatory. In some states and countries it is illegal to tattoo a minor even with parental consent, and it is usually not allowed to tattoo impaired persons, people with contraindicated skin conditions, those who are pregnant or nursing, those incapable of consent due to mental incapacity or those under the influence of alcohol or drugs.
Before the tattooing begins the client is asked to approve the final position of the applied stencil. After approval is given the artist will open new, sterile needle packages in front of the client, and always use new, sterile or sterile disposable instruments and supplies, and fresh ink for each session (loaded into disposable ink caps which are discarded after each client). Also, all areas which may be touched with contaminated gloves will be wrapped in clear plastic to prevent cross-contamination. Equipment that cannot be autoclaved (such as counter tops, machines, and furniture) will be wiped with an approved disinfectant.[8]
Membership in professional organizations, or certificates of appreciation/achievement, generally helps artists to be aware of the latest trends. However, many of the most notable tattooists do not belong to any association. While specific requirements to become a tattooist vary between jurisdictions, many mandate only formal training in bloodborne pathogens, and cross contamination. The local department of health regulates tattoo studios in many jurisdictions.
For example, according to the health department in Oregon and Hawaii, tattoo artists in these states are required to take and pass a test ascertaining their knowledge of health and safety precautions, as well as the current state regulations. Performing a tattoo in Oregon state without a proper and current license or in an unlicensed facility is considered a felony offense.[9] Tattooing was legalized in New York City, Massachusetts, and Oklahoma between 2002 and 2006.
## Aftercare
Tattoo artists, and people with tattoos, vary widely in their preferred methods of caring for new tattoos. Some artists recommend keeping a new tattoo wrapped for the first twenty-four hours, while others suggest removing temporary bandaging after two hours or less. Many tattooists advise against allowing too much contact with hot tub or pool water, or soaking in a tub for the first two weeks. This is to prevent the tattoo ink from washing out or fading due to over-hydration and avoid infection from exposure to bacteria and chlorine. In contrast, other artists suggest that a new tattoo be bathed in very hot water early and often.
General consensus for care advises against removing the scab that forms on a new tattoo, and avoiding exposing one's tattoo to the sun for extended periods; both of these can contribute to fading of the image. Furthermore, it is agreed that a new tattoo needs to be kept clean. Various products may be recommended for application to the skin, ranging from those intended for the treatment of cuts, burns and scrapes, to cocoa butter, lanolin, A&D or Aquaphor. Oil based ointments are almost always recommended to be used in very thin layers due to their inability to evaporate and therefore over-hydrate the already perforated skin. In recent years, specific commercial products have been developed for tattoo aftercare. Although opinions about these products vary, there is near total agreement that either alone or in addition to some other product, soap and warm water work well to keep a tattoo clean and free from infection.Template:Ref labelHowever, salt water can cause a fresh wound to sting as well as leave it vulnerable to infections and fading. [10]
Ultimately, the amount of ink that remains in the skin throughout the healing process determines, in large part, how robust the final tattoo will look. If a tattoo becomes infected (uncommon but possible if one neglects to properly clean their tattoo) or if the scab falls off too soon (e.g., if it absorbs too much water and sloughs off early or is picked or scraped off), then the ink will not be properly fixed in the skin and the final image will be negatively affected.
## Tattoo removal
While tattoos are considered permanent, it is possible to remove them. Complete removal, however, may not be possible (although many doctors and laser practitioners make the claim that upwards of 95% removal is possible with the newest lasers, especially with black and darker colored inks), and the expense and pain of removing them typically will be greater than the expense and pain of applying them. Some jurisdictions will pay for the voluntary removal of gang tattoos. Gangs will often involuntarily remove gang tattoos, from a person who leaves the gang. Pre-laser tattoo removal methods include dermabrasion, salabrasion (scrubbing the skin with salt), cryosurgery, and excision which is sometimes still used along with skin grafts for larger tattoos.
Tattoo removal is most commonly performed using lasers that react with the ink in the tattoo, and break it down. The broken-down ink is then absorbed by the body, mimicking the natural fading that time or sun exposure would create. This technique often requires many repeated visits to remove even a small tattoo, and may result in permanent scarring. The newer Q-switched lasers are said by the National Institute of Health to result in scarring only rarely, however, and are usually used only after a topical anesthetic has been applied. The NIH recognizes five types of tattoo; amateur, professional, cosmetic, medical, and traumatic (or natural). Areas with thin skin will be more likely to scar than thicker-skinned areas. There are several types of Q-switched lasers, and each is effective at removing a different range of the color spectrum. This laser effectively removes black, blue, purple and red tattoo pigment. New lasers like the Versapulse & Medlite laser treat these colors & yellow and green ink pigment, typically the hardest colors to remove. Black is the easiest color to remove.
Also worth considering is the fact that some of the pigments used (especially Yellow #7) are known to break down into toxic chemicals in the body when attacked by light. This is especially a concern if these tattoos are exposed to UV light or laser removal; the resulting degradation products end up migrating to the kidneys and liver. Laser removal of traumatic tattoos may similarly be complicated depending on the substance of the pigmenting material. In one reported instance, the use of a laser resulted in the ignition of embedded particles of firework debris.[11]
Some wearers opt to cover an unwanted tattoo with a new tattoo. This is commonly known as a cover-up. An artfully done cover-up may render the old tattoo completely invisible, though this will depend largely on the size, style, colors and techniques used on the old tattoo. Some shops and artists use laser removal machines to break down and lighten undesired tattoos to make coverage with a new tattoo easier. Since tattoo ink is translucent, covering up a previous tattoo necessitates darker tones in the new tattoo to effectively hide the older, unwanted piece.
# Records
The current record for the most studio tattoos in a 24 hour period goes to Oliver Peck of Dallas, TX. Previously, the reality star Katherine Von Drachenberg, also known as Kat Von D, star of the reality TV show "LA Ink" on TLC was the record holder. Her tattoos were of the LA Ink logo while the current record holder's artwork consists of the number thirteen.
# Health risks
Because it requires breaking the skin barrier, tattooing may carry health risks, including infection and allergic reactions. In the United States, for example, the Red Cross prohibits a person who has received a tattoo from donating blood for 12 months (FDA 2000), unless the procedure was done in a state-regulated and licensed studio, using sterile technique.[6]. Not all states have a licensing program, meaning that people who receive tattoos in those states are subject to the 12-month deferral regardless of the hygienic standards of the studio. Similarly, the UK does not provide certification for tattooists, and so there is a six month waiting period without exception.[12]
Modern western tattooers reduce such risks by following universal precautions, working with single-use items, and sterilizing their equipment after each use. Many jurisdictions require that tattooists have bloodborne pathogen training, such as is provided through the Red Cross and OSHA.
## Infection
Since tattoo instruments come in contact with blood and bodily fluids, diseases may be transmitted if the instruments are used on more than one person without being sterilized. However, infection from tattooing in clean and modern tattoo studios employing single-use needles is rare. In amateur tattoos, such as those applied in prisons, however, there is an elevated risk of infection. To address this problem, a program was introduced in Canada as of the summer of 2005 that provides legal tattooing in prisons, both to reduce health risks and to provide inmates with a marketable skill. Inmates were to be trained to staff and operate the tattoo parlors once six of them opened successfully.Template:Ref label
Infections that could be transmitted via the use of unsterilized tattoo equipment include surface infections of the skin, herpes simplex virus, tetanus, staph (Infected Tattoo), fungal infections, some forms of hepatitis, and HIV. No person in the United States is reported to have contracted HIV via a commercially-applied tattooing process.[citation needed] Washington state's OSHA studies have suggested that since the needles used in tattooing are not hollow, in the case of a needle stick injury the amount of fluids transmitted may be small enough that HIV would be difficult to transmit. Tetanus risk is prevented by having an up-to-date tetanus booster prior to being tattooed. The Centers for Disease Control and Prevention states that no data exist in the United States indicating that persons with exposures to tattooing alone are at increased risk for HCV infection. In 2006, the CDC reported 3 clusters with 44 cases of methicillin-resistant staph infection traced to unlicensed tattooists (MMWR 55(24)).
## Allergic reactions
Perhaps due to the mechanism whereby the skin's immune system encapsulates pigment particles in fibrous tissue, tattoo inks have been described as "remarkably nonreactive histologically".[7]
Allergic reactions to tattoo pigments are uncommon except for certain brands of red and green. People who are sensitive or allergic to certain metals may react to pigments in the skin with swelling and/or itching, and/or oozing of clear fluid called serum. Such reactions are quite rare, however, and some artists will recommend performing a test patch.
For those who are allergic to latex, many artists are using non-latex or will use non-latex gloves if asked.
There is also a small risk of anaphylactic shock (hypersensitive reaction) in those who are susceptible, but the chance of a health risk is small.
Due to the fact that laser removal of tattoo ink causes a release of ink into the bloodstream the risk of anaphylactic shock is also present during removal.[13]
## Tattoo inks
Modern tattooing inks are carbon based pigments that have uses outside of commercial tattoo applications. Although the United States Food and Drug Administration technically requires premarket approval of pigments it has not actually approved the use of any ink or pigments for tattooing (because of a lack of resources for such relatively minor responsibilities).[citation needed] As of 2004 the FDA does perform studies to determine if the contents are possibly dangerous, and follow up with legal action if they find them to have disallowed contents, including traces of heavy metals (such as iron oxide) or other carcinogenic materials (see CA lawsuit). The first known study to characterize the composition of these pigments was started in 2005 at Northern Arizona University (Finley-Jones and Wagner). The FDA expects local authorities to legislate and test tattoo pigments and inks made for the use of permanent cosmetics. In California, the state prohibits certain ingredients and pursues companies who fail to notify the consumer of the contents of tattoo pigments. Recently, the state of California sued nine pigment and ink manufacturers, requiring them to more adequately label their products.
Acrylonitrile butadiene styrene (ABS plastic) ground down to an average diameter of slightly less than 1 micrometer is used as the colorant in the brighter tattoo pigments. The tattoo pigments that use ABS result in very vivid tattoos. Many popular brands of tattoo pigment contain ABS as a colorant. ABS colorants produce extremely vivid tattoos that are less likely to fade or blur than the traditional pigments, but ABS tattoo pigment is also harder to remove because it is so much less reactive to lasers.
There has been concern expressed about the interaction between magnetic resonance imaging (MRI) procedures and tattoo pigments, some of which contain trace metals. Allegedly, the magnetic fields produced by MRI machines could interact with these metal particles, potentially causing burns or distortions in the image. The television show MythBusters tested the theory, and found no interaction between tattoo inks and MRI.
However, research by Shellock and Crues reports adverse reactions to MRI and tattoos in a very small number of cases. Wagle and Smith also documented an isolated case of Tattoo-Induced Skin Burn During MR Imaging. The person in the case had a dark, concentrated, loop-shaped tattoo, which the authors speculate could have acted as an RF (radio frequency) pick-up; they also note that this is the first such case they encountered in "thousands of MRI studies". Ratnapalan et al. report another case where an MRI could not be completed due to the patient's extensive tattoos. According to the American Chemical society, homemade tattoos, in which metallic inks have been used in larger quantities, cause these reactions.
Professional tattoists rely primarily on the same pigment base found in cosmetics. Amateurs will often use drawing inks such as Higgins, Pelikan or India ink, but these inks often contain impurities and toxins which can lead to illness or infection. A "green haze" is a telltale sign of a tattoo done with drawing ink.
# Temporary tattoos
Temporary tattoos are popular with models and children as they involve no permanent alteration of the skin but produce a similar appearance that can last anywhere from a few days to several weeks. The most common style is a type of body sticker similar to a decal, which is typically transferred to the skin using water. Although the design is waterproof, it can be removed easily with oil-based creams. Originally inserted as a prize in bubble gum packages, they consisted of a poor quality ink transfer that would easily come off with water or rubbing. Today's vegetable dye temporaries can look extremely realistic and adhere up to 3 weeks due to a layer of glue similar to that found on an adhesive bandage.
Henna tattoos, also known as Mehndi, and silver nitrate stains that appear when exposed to ultraviolet light, can take up to two weeks to fade from the skin. Temporary airbrush tattoos (TATs) are applied by covering the skin with a stencil and spraying the skin with ink. In the past, this form of tattoo only lasted about a week. With the newest inks, tattoos can reasonably last for up to two weeks.
Magician Penn Jillette (of Penn & Teller fame) writes in his book Penn & Teller's How to Play in Traffic that he had a special tattoo made on his arm that used no pigment (the tattoo machine was run without ink).[citation needed] Penn states that the tattoo left a red scar that had a discernible pattern, but would heal to near invisibility after five or six weeks. When filming the remake of Cape Fear, actor Robert De Niro was tattooed with Temptu Ink, a body paint formulated by chemist Samuel Zuckerman.[citation needed] | https://www.wikidoc.org/index.php/Tattoo | |
e7de670a472c99b6b7324f67a6862448d2582be4 | wikidoc | Tektin | Tektin
Tektins are cytoskeletal proteins found in cilia and flagella as structural components of outer doublet microtubules. They are also present in centrioles and basal bodies. They are polymeric in nature, and form filaments.
# Structure
Tektin filaments are 2 to 3 nm diameter with two alpha helical segments. They have the consensus amino acid sequence of RPNVELCRD. Different types of tektins, designated as A (53 kDa), B (51 kDa), C (47 kDa) form dimers, trimers and oligomers in various combinations and are also associated with tubulin in the microtubule. Tektins A and B form heteropolymeric protofilaments whereas tektin C forms homodimers. Tektin filaments are present in a supercoiled state. This structure of tektins suggests that they are evolutionarily related to intermediate filaments.
# Function
Tektins as integral components of microtubules are essential for their structural integrity. A mutation in the tektin-t genes may lead to defects in flagellar activity which could manifest, for instance, as immotility of sperm leading to male infertility. Tektins are thought to be involved in the assembly of the basal body. The study of tektins has also been found to be useful in phylogeny, to establish evolutionary relationship between organisms. Amino acid sequences of tektins are well conserved, with significant similarity between mouse and human homologs. | Tektin
Tektins are cytoskeletal proteins found in cilia and flagella as structural components of outer doublet microtubules. They are also present in centrioles and basal bodies. They are polymeric in nature, and form filaments.[1]
# Structure
Tektin filaments are 2 to 3 nm diameter with two alpha helical segments. They have the consensus amino acid sequence of RPNVELCRD. Different types of tektins, designated as A (53 kDa), B (51 kDa), C (47 kDa) form dimers, trimers and oligomers in various combinations and are also associated with tubulin in the microtubule. Tektins A and B form heteropolymeric protofilaments whereas tektin C forms homodimers. Tektin filaments are present in a supercoiled state. [2] This structure of tektins suggests that they are evolutionarily related to intermediate filaments.[3]
# Function
Tektins as integral components of microtubules are essential for their structural integrity. A mutation in the tektin-t genes may lead to defects in flagellar activity which could manifest, for instance, as immotility of sperm leading to male infertility. [4] Tektins are thought to be involved in the assembly of the basal body. [5] The study of tektins has also been found to be useful in phylogeny, to establish evolutionary relationship between organisms.[6] Amino acid sequences of tektins are well conserved, with significant similarity between mouse and human homologs. | https://www.wikidoc.org/index.php/Tektin | |
97be8707a26a3e997babbb8aad80ae4ea820df01 | wikidoc | Tendon | Tendon
# Overview
A tendon (or sinew) is a tough band of fibrous connective tissue that connects muscle to bone and is built to withstand tension. Tendons are similar to ligaments except that ligaments join one bone to another. Tendons and muscles work together and can only exert a pulling force.
# Anatomy
The origin of a tendon is where it joins to a muscle. Collagen fibers from within the muscle organ are continuous with those of the tendon. A tendon inserts into bone at an enthesis where the collagen fibers are mineralised and integrated into bone tissue. While they exert no pulling force of their own, tendons transfer the contractions of muscles and can exert an elastic force if forcibly stretched.
Tenocytes produce collagen molecules which aggregate end-to-end and side-to-side to produce collagen fibrils. Fibril bundles are organised by tenocytes to form fibres. Collagen fibres coalesce into macroaggregates. Groups of macroaggregates are bounded by connective tissue endotendon and are termed fascicles. Groups of fascicles are bounded by the epitendon and peritendon to form the tendon organ.
Blood vessels may be visualised within the endotendon running parallel to collagen fibres, with occasional branching transverse anastomoses.
The internal tendon bulk is thought to contain no nerve fibres, but the epi- and peritendon contain nerve endings, while Golgi tendon organs are present at the junction between tendon and muscle.
Tendon length varies in all major groups and from person to person. Tendon length is practically the discerning factor where muscle size and potential muscle size is concerned. For example, should all other relevant biological factors be equal, a man with a shorter tendons and a longer biceps muscle will have greater potential for muscle mass than a man with a longer tendon and a shorter muscle. Cases in point: successful bodybuilders will generally have short tendons and are said to have 'great genetics.' Examples of people with short tendons (in particular the upper arms) are Casey Viator and Arnold Schwarzenegger. Conversely, in sports requiring athletes to excel in actions such as running or jumping, it is beneficial to have longer than average and a shorter calf muscle Some of the many professional athletes with long achilles tendons include Allen Iverson, Justin Gatlin and Hicham El Guerrouj. Tendon length is determined by genes, and has not been shown to either increase or decrease in response to environment, unlike muscles which can be shortened by trauma, use imbalances and a lack of recovery and stretching.
# Other information
Tendonitis refers to inflammation of a tendon.
The Achilles tendon is a particularly large tendon connecting the heel to the muscles of the calf. It is is so named because the mythic hero Achilles was said to have been killed due to an injury to this area.
Sinew was also widely used throughout pre-industrial eras as a tough, durable fibre. Some specific uses include using sinew as thread for sewing, attaching feathers to arrows (see fletch), lashing tool blades to shafts, etc. It also recommended in survival guides as a material from which strong cordage can be made for items like traps or living structures. Tendon must be treated in specific ways to function usefully for these purposes. Inuit and other circumpolar people utilised sinew as the only cordage for all domestic purposes due to the lack of other suitable fibre sources in their ecological habitats. | Tendon
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
# Overview
A tendon (or sinew) is a tough band of fibrous connective tissue that connects muscle to bone and is built to withstand tension. Tendons are similar to ligaments except that ligaments join one bone to another. Tendons and muscles work together and can only exert a pulling force.
# Anatomy
The origin of a tendon is where it joins to a muscle. Collagen fibers from within the muscle organ are continuous with those of the tendon. A tendon inserts into bone at an enthesis where the collagen fibers are mineralised and integrated into bone tissue. While they exert no pulling force of their own, tendons transfer the contractions of muscles and can exert an elastic force if forcibly stretched.
Tenocytes produce collagen molecules which aggregate end-to-end and side-to-side to produce collagen fibrils. Fibril bundles are organised by tenocytes to form fibres. Collagen fibres coalesce into macroaggregates. Groups of macroaggregates are bounded by connective tissue endotendon and are termed fascicles. Groups of fascicles are bounded by the epitendon and peritendon to form the tendon organ.
Blood vessels may be visualised within the endotendon running parallel to collagen fibres, with occasional branching transverse anastomoses.
The internal tendon bulk is thought to contain no nerve fibres, but the epi- and peritendon contain nerve endings, while Golgi tendon organs are present at the junction between tendon and muscle.
Tendon length varies in all major groups and from person to person. Tendon length is practically the discerning factor where muscle size and potential muscle size is concerned. For example, should all other relevant biological factors be equal, a man with a shorter tendons and a longer biceps muscle will have greater potential for muscle mass than a man with a longer tendon and a shorter muscle. Cases in point: successful bodybuilders will generally have short tendons and are said to have 'great genetics.' Examples of people with short tendons (in particular the upper arms) are Casey Viator and Arnold Schwarzenegger. Conversely, in sports requiring athletes to excel in actions such as running or jumping, it is beneficial to have longer than average [[achilles tendon] and a shorter calf muscle [1] Some of the many professional athletes with long achilles tendons include Allen Iverson, Justin Gatlin and Hicham El Guerrouj. Tendon length is determined by genes, and has not been shown to either increase or decrease in response to environment, unlike muscles which can be shortened by trauma, use imbalances and a lack of recovery and stretching.
# Other information
Tendonitis refers to inflammation of a tendon.
The Achilles tendon is a particularly large tendon connecting the heel to the muscles of the calf. It is is so named because the mythic hero Achilles was said to have been killed due to an injury to this area.
Sinew was also widely used throughout pre-industrial eras as a tough, durable fibre. Some specific uses include using sinew as thread for sewing, attaching feathers to arrows (see fletch), lashing tool blades to shafts, etc. It also recommended in survival guides as a material from which strong cordage can be made for items like traps or living structures. Tendon must be treated in specific ways to function usefully for these purposes. Inuit and other circumpolar people utilised sinew as the only cordage for all domestic purposes due to the lack of other suitable fibre sources in their ecological habitats. | https://www.wikidoc.org/index.php/Tendon | |
915ddeecc80d6e702b03f2983a812acfd557bb57 | wikidoc | Testin | Testin
Testin also known as TESS is a protein that in humans is encoded by the TES gene located on chromosome 7. TES is a 47 kDa protein composed of 421 amino acids found at focal adhesions and is thought to have a role in regulation of cell motility. In addition to this, TES functions as a tumour suppressor. The TES gene is located within a fragile region of chromosome 7, and the promoter elements of the TES gene have been shown to be susceptible to methylation – this prevents the expression of the TES protein. TES came to greater prominence towards the end of 2007 as a potential mechanism for its tumour suppressor function was published.
# Domain organisation
Tes is composed of the following domains:
The structures of the Cysteine rich domain and the PET domain are not known. LIM domains, however, are known as modulators of protein interactions. LIM domain consist of 2 zinc fingers separated by 2 hydrophobic amino acids (generally a phenylalanine and then a leucine).
# Binding partners
TES does not appear to be an enzyme; rather it is a protein that mediates/regulates cellular functions via protein–protein interactions. Pull down experiments reveal that TES has putative interactions mediated by the indicated domain:
Garvalov et al. showed that the interaction between TES & zyxin were direct, using recombinant proteins expressed in E. coli.
Some of the potential binding partners (Zyxin, mENA) can be found in focal adhesion complexes; the range of binding partners indicates a potential role for TES in-between 'privileged' Actin polymerisation and focal adhesion contacts to the extracellular matrix. This tallies with the observation that GFP-tagged TES can be seen at focal adhesions.
# TES as a tumour suppressor
In December 2007, Boeda, Briggs et al. showed that the third LIM domain of TES displaces Mena from its usual subcellular positions (focal adhesions or the cell leading edge). The ENA/VASP protein family (of which Mena is a member) are anchored to specific proteins within the cell by a peptide motif consisting of a phenylalanine residue, followed by four proline residues – known as a FPPPP motif. It is the EVH1 domains of VASP/EVL proteins that directly contact the FPPPP motif. The precise architecture of TES:MENA binding was revealed by X-ray crystallography, and showed that the 3rd LIM domain of TES covered up the FPPPP binding site within Menas EVH1 domain. Isothermal titration calorimetry showed that TES has a greater affinity for Mena than its canonical FPPPP ligand, as presented in the focal adhesion protein zyxin. Using microscopy it was shown that either over-expression of GFP-tagged TES, or just the tagged third LIM domain displaced Mena from focal adhesions and reduced mean cell velocity.
These finding were significant given that Mena is often over-expressed in cancer cells, and is thought to be partly responsible for cancer cell motility, and therefore a factor in cancer metastasis. TES is conversely often not produced in cancer cells. It is possible that a drug designed to mimic TES's interaction with Mena could be used to prevent metastasis and thus development of secondary tumours in cancer patients. The work was widely reported in the British press (the work was carried out by Cancer Research UK), and also in the international press.
# Conformational change
Based on the observations that:
- Mammalian cell derived TES binding Zyxin
- E. coli-produced recombinant TES (rTES) does not bind Zyxin
- An rTES construct composed of residues 201–421 (i.e., the linker and all 3 LIM domains) does bind Zyxin
- The above rTES construct binds an N-terminal rTES construct, consisting of the cysteine rich and PET domains – IE, the two-halves of TES interact with each other.
Garvalov et al. propose that TES exists in two conformational states: A 'closed' state where the N & C halves of TES interact, obscuring the Zyxin binding site in LIM1, and an 'open' state where the Zyxin binding site is accessible and the two halves no-longer interact in the same fashion, if at all. The regulatory mechanism switching between the two states is not presently fully understood.
# Phenotype
In RNAi experiments, cells that had impaired TES expression showed an inability to correctly organise their focal adhesions and actin stress fibres.
In gene knockout experiments, transgenic mice lacking both copies of the TES gene displayed an increased susceptibility to tumour formation when challenged with a carcinogen. Mice retaining the TES gene were less susceptible: thus, TES is a tumour suppressor gene. | Testin
Testin also known as TESS is a protein that in humans is encoded by the TES gene located on chromosome 7.[1] TES is a 47 kDa protein composed of 421 amino acids found at focal adhesions and is thought to have a role in regulation of cell motility.[2] In addition to this, TES functions as a tumour suppressor.[3] The TES gene is located within a fragile region of chromosome 7, and the promoter elements of the TES gene have been shown to be susceptible to methylation – this prevents the expression of the TES protein. TES came to greater prominence towards the end of 2007 as a potential mechanism for its tumour suppressor function was published.
# Domain organisation
Tes is composed of the following domains:
The structures of the Cysteine rich domain and the PET domain are not known. LIM domains, however, are known as modulators of protein interactions.[4] LIM domain consist of 2 zinc fingers separated by 2 hydrophobic amino acids (generally a phenylalanine and then a leucine).
# Binding partners
TES does not appear to be an enzyme; rather it is a protein that mediates/regulates cellular functions via protein–protein interactions. Pull down experiments[5] reveal that TES has putative interactions mediated by the indicated domain:
Garvalov et al. showed that the interaction between TES & zyxin were direct, using recombinant proteins expressed in E. coli.[5]
Some of the potential binding partners (Zyxin, mENA) can be found in focal adhesion complexes; the range of binding partners indicates a potential role for TES in-between 'privileged' Actin polymerisation and focal adhesion contacts to the extracellular matrix. This tallies with the observation that GFP-tagged TES can be seen at focal adhesions.
# TES as a tumour suppressor
In December 2007, Boeda, Briggs et al.[6] showed that the third LIM domain of TES displaces Mena from its usual subcellular positions (focal adhesions or the cell leading edge). The ENA/VASP protein family (of which Mena is a member) are anchored to specific proteins within the cell by a peptide motif consisting of a phenylalanine residue, followed by four proline residues – known as a FPPPP motif. It is the EVH1 domains of VASP/EVL proteins that directly contact the FPPPP motif. The precise architecture of TES:MENA binding was revealed by X-ray crystallography, and showed that the 3rd LIM domain of TES covered up the FPPPP binding site within Menas EVH1 domain. Isothermal titration calorimetry showed that TES has a greater affinity for Mena than its canonical FPPPP ligand, as presented in the focal adhesion protein zyxin. Using microscopy it was shown that either over-expression of GFP-tagged TES, or just the tagged third LIM domain displaced Mena from focal adhesions and reduced mean cell velocity.
These finding were significant given that Mena is often over-expressed in cancer cells, and is thought to be partly responsible for cancer cell motility, and therefore a factor in cancer metastasis. TES is conversely often not produced in cancer cells. It is possible that a drug designed to mimic TES's interaction with Mena could be used to prevent metastasis and thus development of secondary tumours in cancer patients. The work was widely reported in the British press (the work was carried out by Cancer Research UK),[7][8][9] and also in the international press.[10][11]
# Conformational change
Based on the observations that:[citation needed]
- Mammalian cell derived TES binding Zyxin
- E. coli-produced recombinant TES (rTES) does not bind Zyxin
- An rTES construct composed of residues 201–421 (i.e., the linker and all 3 LIM domains) does bind Zyxin
- The above rTES construct binds an N-terminal rTES construct, consisting of the cysteine rich and PET domains – IE, the two-halves of TES interact with each other.
Garvalov et al. propose that TES exists in two conformational states: A 'closed' state where the N & C halves of TES interact, obscuring the Zyxin binding site in LIM1, and an 'open' state where the Zyxin binding site is accessible and the two halves no-longer interact in the same fashion, if at all. The regulatory mechanism switching between the two states is not presently fully understood.
# Phenotype
In RNAi experiments, cells that had impaired TES expression showed an inability to correctly organise their focal adhesions and actin stress fibres.
In gene knockout experiments, transgenic mice lacking both copies of the TES gene displayed an increased susceptibility to tumour formation when challenged with a carcinogen. Mice retaining the TES gene were less susceptible: thus, TES is a tumour suppressor gene. | https://www.wikidoc.org/index.php/Testin | |
c72dd2ca41014c8b53ea41006d3005854f17a05d | wikidoc | Thiram | Thiram
# Overview
Synonyms and keywords: Tetramethylthiuram disulfide
# Overview
Thiram is an ectoparasiticide. It is used to prevent fungal diseases in seed and crops. It is also used as an animal repellent to protect fruit trees and ornamentals from damage by rabbits, rodents and deer. It is effective against Stem gall of coriander, damping off, smut of millet, neck rot of onion, etc. Thiram has been used in the treatment of human scabies, as a sun screen and as a bactericide applied directly to the skin or incorporated into soap.
# Chemical properties
Thiram is a type of sulfur fungicide. It has been found to dissolve completely in chloroform, acetone and ether. It is available as dust, flowable, wettable powder, water dispersible granules, and water suspension formulations and in mixtures with other fungicides.
Thiram is nearly immobile in clay soils or in soils of high organic matter. It is not expected to contaminate groundwater because of its in-soil half life of 15 days and tendency to stick to soil particles.
# Acute Toxicity
Thiram is moderately toxic by ingestion, but it is highly toxic if inhaled. Acute exposure in humans may cause headaches, dizziness, fatigue, nausea, diarrhea and other gastrointestinal complaints.
Thiram is irritating to the eyes, skin and respiratory tract. It is a skin sensitizer. Symptoms of acute inhalation exposure to thiram include itching, scratchy throat, hoarseness, sneezing, coughing, inflammation of the nose or throat, bronchitis, dizziness, headaches, fatigue, nausea, diarrhea and other gastro-intestinal complaints. Persons with chronic respiratory or skin disease are at increased risk from exposure to thiram.
# Chronic Toxicity
In addition to the symptoms of acute exposure, symptoms of chronic exposure to thiram in humans include drowsiness, confusion, loss of sex drive, incoordination, slurred speech and weakness. Repeated or prolonged exposure to thiram can also cause allergic reactions such as dermatitis, watery eyes, sensitivity to light and conjunctivitis. | Thiram
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
# Overview
Synonyms and keywords: Tetramethylthiuram disulfide
# Overview
Thiram is an ectoparasiticide. It is used to prevent fungal diseases in seed and crops. It is also used as an animal repellent to protect fruit trees and ornamentals from damage by rabbits, rodents and deer. It is effective against Stem gall of coriander, damping off, smut of millet, neck rot of onion, etc. Thiram has been used in the treatment of human scabies, as a sun screen and as a bactericide applied directly to the skin or incorporated into soap.[2]
# Chemical properties
Thiram is a type of sulfur fungicide. It has been found to dissolve completely in chloroform, acetone and ether. It is available as dust, flowable, wettable powder, water dispersible granules, and water suspension formulations and in mixtures with other fungicides. [3]
Thiram is nearly immobile in clay soils or in soils of high organic matter. It is not expected to contaminate groundwater because of its in-soil half life of 15 days and tendency to stick to soil particles. [4]
# Acute Toxicity
Thiram is moderately toxic by ingestion, but it is highly toxic if inhaled. Acute exposure in humans may cause headaches, dizziness, fatigue, nausea, diarrhea and other gastrointestinal complaints. [5]
Thiram is irritating to the eyes, skin and respiratory tract. It is a skin sensitizer. Symptoms of acute inhalation exposure to thiram include itching, scratchy throat, hoarseness, sneezing, coughing, inflammation of the nose or throat, bronchitis, dizziness, headaches, fatigue, nausea, diarrhea and other gastro-intestinal complaints. Persons with chronic respiratory or skin disease are at increased risk from exposure to thiram.
# Chronic Toxicity
In addition to the symptoms of acute exposure, symptoms of chronic exposure to thiram in humans include drowsiness, confusion, loss of sex drive, incoordination, slurred speech and weakness. Repeated or prolonged exposure to thiram can also cause allergic reactions such as dermatitis, watery eyes, sensitivity to light and conjunctivitis. | https://www.wikidoc.org/index.php/Tetramethylthiuram_disulfide | |
3bfae389ecc6fe0fac0c3f1f3ab6ead19f25ae57 | wikidoc | Theria | Theria
Theria (Template:PronEng, from the Greek θηρίον, wild beast) is a subclass of mammals that give birth to live young without using a shelled egg, including both eutherians (placental mammals) and metatherians (marsupials and their ancestors).
# Extent
The subclass includes humans. They have external ears, most can suckle on a nipple, and have an ankle specialized for power and range of motion. Therians are often classified by their specialized dentition.
Almost all currently extant (not extinct) mammals are therians. The only exceptions are the platypus and the echidnas (spiny anteater), both of which are prototherian monotremes.
# Bibliography
- Vaughan, Terry A., James M. Ryan, and Nicholas J. Czaplewski. 2000. Mammalogy: Fourth Edition. Saunders College Publishing, 565 pp. ISBN 0-03-025034-X | Theria
Theria (Template:PronEng, from the Greek θηρίον, wild beast) is a subclass of mammals[1] that give birth to live young without using a shelled egg, including both eutherians (placental mammals) and metatherians (marsupials and their ancestors).
# Extent
The subclass includes humans. They have external ears, most can suckle on a nipple, and have an ankle specialized for power and range of motion. Therians are often classified by their specialized dentition.
Almost all currently extant (not extinct) mammals are therians. The only exceptions are the platypus and the echidnas (spiny anteater), both of which are prototherian monotremes.
# Bibliography
- Vaughan, Terry A., James M. Ryan, and Nicholas J. Czaplewski. 2000. Mammalogy: Fourth Edition. Saunders College Publishing, 565 pp. ISBN 0-03-025034-X | https://www.wikidoc.org/index.php/Theria | |
7cc88de28ce2d304b046350463378307060add1b | wikidoc | Thirst | Thirst
# Overview
Thirst is the craving for liquids, resulting in the basic instinct of humans or animals to drink. It is an essential mechanism involved in fluid balance. It arises from a lack of fluids and/or an increase in the concentration of certain osmolytes such as salt. If the water volume of the body falls below a certain threshold, or the osmolite concentration becomes too high, the brain signals thirst.
Continuous dehydration can cause a myriad of problems, but is most often associated with neurological problems such as seizures, and renal problems.
Excessive thirst, known as polydipsia, along with excessive urination, known as polyuria, may be an indication of diabetes.
There are receptors and other systems in the body that detect a decreased volume or an increased osmolite concentration. They signal to the central nervous system, where central processing succeeds. Some sources therefore distinguish "Extracellular thirst" from "intracellular thirst", where extracellular thirst is thirst generated by decreased volume and intracellular thirst is thirst generated by increased osmolite concentration. Nevertheless, the craving itself is something generated from central processing in the brain, no matter how it is detected.
# Detection
There are different receptors for sensing decreased volume or an increased osmolite concentration.
## Decreased volume
- Renin-angiotensin system
Hypovolemia leads to activation of the renin angiotensin system (RAS) and a decrease in atrial natriuretic peptide. These mechanisms, along their other functions, contribute to elicit thirst, by affecting the subfornical organ.. For instance, angiotensin II, activated in RAS, is a powerful dipsogen (ie it stimulates thirst) which acts via the subfornical organ.
- Other
Arterial baroreceptors sense a decreased arterial pressure, and signals to the central nervous system in the area postrema and nucleus tractus solitarius.
Cardiopulmonary receptors sense a decreased blood volume, and signal to area postrema and nucleus tractus solitarius as well.
- Arterial baroreceptors sense a decreased arterial pressure, and signals to the central nervous system in the area postrema and nucleus tractus solitarius.
- Cardiopulmonary receptors sense a decreased blood volume, and signal to area postrema and nucleus tractus solitarius as well.
## Increased osmolite concentration
An increase in osmotic pressure, e.g. after eating a salty meal activates osmoreceptors. There are osmoreceptors already in the central nervous system, morespecifically in the hypothalamus, notably in two circumventricular organs that lack an effective blood-brain barrier, the organum vasculosum of the lamina terminalis (OVLT) and the subfornical organ (SFO). However, although located in the same parts of the brain, these osmoreceptors that evoke thirst are distinct from the neighbouring osmoreceptors in the OVLT and SFO that evoke arginine vasopressin release to decrease fluid output.
In addition, there are visceral osmoreceptors. These project to the area postrema and nucleus tractus solitarius in the brain.
## Salt craving
Because sodium is also lost the from the plasma in hypovolemia, the body's need for salt proportionately increases in addition to thirst in such cases.. This is also a result of the renin-angiotensin system activation.
# Central processing
The area postrema and nucleus tractus solitarius signal, by 5-HT, to lateral parabrachial nucleus, which in turn signal to median preoptic nucleus. In addition, the area postrema and nucleus tractus solitarius also signal directly to subfornical organ.
Thus, the median preoptic nucleus and subfornical organ receive signals of both decreased volume and increased osmolite concentration. They signal to higher integrative centers, where ultimately the conscious craving arises. However, the true neuroscience of this conscious craving is not fully clear.
In addition to thirst, the organum vasculosum of the lamina terminalis and the subfornical organ contribute to fluid balance by vasopressin release.
# Preventing subtle dehydration
For optimal health, experts recommend that humans get 8-10 servings of about 8-ounces of water (in total, approximately 2 litres) per day to maintain hydration. This figure does vary according to ambient temperature, movement and physical size. Being that water is essential to the general function of the human and all animal bodies, eight servings is widely regarded as the minimum for the body to function optimally. However, water can be obtained from many sources, such as foods and other beverages containing water. Getting enough water from your diet and staying hydrated is key to your overall health, including urinary tract and digestive tract health.
When getting your daily water intake, it's important to not rely heavily on caffeinated beverages, as they actually work as a diuretic. Further, moderate or excessive alcohol consumption can lead to dehydration, thus it's important to maintain hydration when drinking caffeinated and alcoholic beverages. | Thirst
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
# Overview
Thirst is the craving for liquids, resulting in the basic instinct of humans or animals to drink. It is an essential mechanism involved in fluid balance. It arises from a lack of fluids and/or an increase in the concentration of certain osmolytes such as salt. If the water volume of the body falls below a certain threshold, or the osmolite concentration becomes too high, the brain signals thirst.
Continuous dehydration can cause a myriad of problems, but is most often associated with neurological problems such as seizures, and renal problems.
Excessive thirst, known as polydipsia, along with excessive urination, known as polyuria, may be an indication of diabetes.
There are receptors and other systems in the body that detect a decreased volume or an increased osmolite concentration. They signal to the central nervous system, where central processing succeeds. Some sources[1] therefore distinguish "Extracellular thirst" from "intracellular thirst", where extracellular thirst is thirst generated by decreased volume and intracellular thirst is thirst generated by increased osmolite concentration. Nevertheless, the craving itself is something generated from central processing in the brain, no matter how it is detected.
# Detection
There are different receptors for sensing decreased volume or an increased osmolite concentration.
## Decreased volume
- Renin-angiotensin system
Hypovolemia leads to activation of the renin angiotensin system (RAS) and a decrease in atrial natriuretic peptide. These mechanisms, along their other functions, contribute to elicit thirst, by affecting the subfornical organ.[2]. For instance, angiotensin II, activated in RAS, is a powerful dipsogen (ie it stimulates thirst) which acts via the subfornical organ.
- Other
Arterial baroreceptors sense a decreased arterial pressure, and signals to the central nervous system in the area postrema[2] and nucleus tractus solitarius[2].
Cardiopulmonary receptors sense a decreased blood volume, and signal to area postrema[2] and nucleus tractus solitarius[2] as well.
- Arterial baroreceptors sense a decreased arterial pressure, and signals to the central nervous system in the area postrema[2] and nucleus tractus solitarius[2].
- Cardiopulmonary receptors sense a decreased blood volume, and signal to area postrema[2] and nucleus tractus solitarius[2] as well.
## Increased osmolite concentration
An increase in osmotic pressure, e.g. after eating a salty meal[1] activates osmoreceptors. There are osmoreceptors already in the central nervous system, morespecifically in the hypothalamus, notably in two circumventricular organs that lack an effective blood-brain barrier, the organum vasculosum of the lamina terminalis (OVLT) and the subfornical organ (SFO). However, although located in the same parts of the brain, these osmoreceptors that evoke thirst are distinct from the neighbouring osmoreceptors in the OVLT and SFO that evoke arginine vasopressin release to decrease fluid output.[3]
In addition, there are visceral osmoreceptors[2]. These project to the area postrema[2] and nucleus tractus solitarius[2] in the brain.
## Salt craving
Because sodium is also lost the from the plasma in hypovolemia, the body's need for salt proportionately increases in addition to thirst in such cases.[1]. This is also a result of the renin-angiotensin system activation.
# Central processing
The area postrema and nucleus tractus solitarius signal, by 5-HT[2], to lateral parabrachial nucleus[2], which in turn signal to median preoptic nucleus. In addition, the area postrema and nucleus tractus solitarius also signal directly to subfornical organ.[2]
Thus, the median preoptic nucleus and subfornical organ receive signals of both decreased volume and increased osmolite concentration. They signal to higher integrative centers[2], where ultimately the conscious craving arises. However, the true neuroscience of this conscious craving is not fully clear.
In addition to thirst, the organum vasculosum of the lamina terminalis and the subfornical organ contribute to fluid balance by vasopressin release.
# Preventing subtle dehydration
For optimal health, experts recommend that humans get 8-10 servings of about 8-ounces of water (in total, approximately 2 litres) per day to maintain hydration. This figure does vary according to ambient temperature, movement and physical size. Being that water is essential to the general function of the human and all animal bodies, eight servings is widely regarded as the minimum for the body to function optimally. However, water can be obtained from many sources, such as foods and other beverages containing water. Getting enough water from your diet and staying hydrated is key to your overall health, including urinary tract and digestive tract health.
When getting your daily water intake, it's important to not rely heavily on caffeinated beverages, as they actually work as a diuretic. Further, moderate or excessive alcohol consumption can lead to dehydration, thus it's important to maintain hydration when drinking caffeinated and alcoholic beverages. | https://www.wikidoc.org/index.php/Thirst | |
fe02092f79d64c226f5f53f6fb0b3db2300ab37e | wikidoc | Thymus | Thymus
# Overview
In human anatomy, the thymus is an organ located in the upper anterior portion of the chest cavity just behind the sternum. Hormones produced by this organ stimulate the production of certain infection-fighting cells. It is of central importance in the maturation of T cells.
# History
Due to the large numbers of apoptotic lymphocytes, the thymus was originally dismissed as a "lymphocyte graveyard", without functional importance. The importance of the thymus in the immune system was discovered in 1961 by Jacques Miller, by surgically removing the thymus from three day old mice, and observing the subsequent deficiency in a lymphocyte population, subsequently named T cells after the organ of their origin. Recently advances in immunology have allowed the fine dissection of the function of the thymus in T cell maturation.
# Development
## Embryology
The two main components of the thymus, the lymphoid thymocytes and the thymic epithelial cells, have distinct developmental origins. The thymic epithelium is the first to develop, and appears in the form of two flask-shape endodermal diverticula, which arise, one on either side, from the third branchial pouch (pharyngeal pouch), and extend lateralward and backward into the surrounding mesoderm and neural crest-derived mesenchyme in front of the ventral aorta.
Here they meet and become joined to one another by connective tissue, but there is never any fusion of the thymus tissue proper. The pharyngeal opening of each diverticulum is soon obliterated, but the neck of the flask persists for some time as a cellular cord. By further proliferation of the cells lining the flask, buds of cells are formed, which become surrounded and isolated by the invading mesoderm. Additional portions of thymus tissue are sometimes developed from the fourth branchial pouches.
During the late stages of the development of the thymic epithelium, hematopoietic lymphoid cells from bone-marrow precursors immigrate into the thymus and are aggregated to form lymphoid follicles.
The thymus continues to grow between birth and puberty and then begins to atrophy, a process directed by the high levels of circulating sex hormones. Proportional to thymic size, thymic activity (T cell output) is most active before puberty. Upon atrophy, the size and activity are dramatically reduced, and the organ is primarily replaced with fat (a phenomenon known as "involution"). The atrophy is due to the increased circulating level of sex hormones, and chemical or physical castration of an adult results in the thymus increasing in size and activity.
Patients with the autoimmune disease Myasthenia gravis commonly (70%) are found to have thymic hyperplasia or malignancy. The reason or order of these cirumstances has yet to be determined by medical scientists.
# Anatomy
The thymus is of a pinkish-gray color, soft, and lobulated on its surfaces. At birth it is about 5 cm in length, 4 cm in breadth, and about 6 mm in thickness. The organ enlarges during childhood, and atrophies at puberty.
The thymus will, if examined when its growth is most active, be found to consist of two lateral lobes placed in close contact along the middle line, situated partly in the thorax, partly in the neck, and extending from the fourth costal cartilage upward, as high as the lower border of the thyroid gland.
It is covered by the sternum, and by the origins of the sternohyoidei and sternothyreoidei.
Below, it rests upon the pericardium, being separated from the aortic arch and great vessels by a layer of fascia.
In the neck, it lies on the front and sides of the trachea, behind the sternohyoidei and sternothyreoidei.
The two lobes generally differ in size; they are occasionally united, so as to form a single mass, and sometimes separated by an intermediate lobe.
# Structure
Each lateral lobe is composed of numerous lobules held together by delicate areolar tissue; the entire organ being enclosed in an investing capsule of a similar but denser structure. The primary lobules vary in size from that of a pin's head to that of a small pea, and are made up of a number of small nodules or follicles.
The follicles are irregular in shape and are more or less fused together, especially toward the interior of the organ. Each follicle is from 1 to 2 mm in diameter and consists of a medullary and a cortical portion, and these differ in many essential particulars from each other.
## Cortex
The cortical portion is mainly composed of lymphoid cells, supported by a network of finely-branched epithelial reticular cells, which is continuous with a similar network in the medullary portion. This network forms an adventitia to the blood vessels.
The cortex is the location of the earliest events in thymocyte development, where T cell receptor gene rearrangement and positive selection takes place.
## Medulla
In the medullary portion, the reticulum is coarser than in the cortex, the lymphoid cells are relatively fewer in number, and there are found peculiar nest-like bodies, the concentric corpuscles of Hassall. These concentric corpuscles are composed of a central mass, consisting of one or more granular cells, and of a capsule formed of epithelioid cells. They are the remains of the epithelial tubes, which grow out from the third branchial pouches of the embryo to form the thymus. Each follicle is surrounded by a vascular plexus, from which vessels pass into the interior, and radiate from the periphery toward the center, forming a second zone just within the margin of the medullary portion. In the center of the medullary portion there are very few vessels, and they are of minute size.
The medulla is the location of the latter events in thymocyte development. Thymocytes that reach the medulla have already successfully undergone T cell receptor gene rearrangement and positive selection, and have been exposed to a limited degree of negative selection. The medulla is specialised to allow thymocytes to undergo additional rounds of negative selection to remove auto-reactive T cells from the mature repertoire. The gene AIRE is expressed in the medulla, and drives the transcription of organ-specific genes such as insulin to allow maturing thymocytes to be exposed to a more complex set of self-antigens than is present in the cortex.
## Vasculature
The arteries supplying the thymus are derived from the internal mammary, and from the superior thyroid and inferior thyroids.
The veins end in the left innominate vein, and in the thyroid veins.
The nerves are exceedingly minute; they are derived from the vagi and sympathetic nervous system. Branches from the descendens hypoglossi and phrenic reach the investing capsule, but do not penetrate into the substance of the organ.
# Function
In the two thymic lobes, lymphocyte precursors from the bone-marrow become thymocytes, and subsequently mature into T cells. Once mature, T cells emigrate from the thymus and constitute the peripheral T cell repertoire responsible for directing many facets of the adaptive immune system. Loss of the thymus at an early age through genetic mutation or surgical removal results in severe immunodeficiency and a high susceptibility to infection. .
However up to January 2001, it was thought that whilst the thymus gland is important to the immune system in the developing foetus, the gland becomes redundant after birth, and so can be surgically excised without harm to the patient.
The ability of T cells to recognize foreign antigens is mediated by the T cell receptor. The T cell receptor undergoes genetic rearrangement during thymocyte maturation, resulting in each T cell bearing a unique T cell receptor, specific to a limited set of peptide:MHC combinations. The random nature of the genetic rearrangement results in a requirement of central tolerance mechanisms to remove or inactivate those T cells which bear a T cell receptor with the ability to recognise self-peptides.
## Phases of thymocyte maturation
The generation of T cells expressing distinct T cell receptors occurs within the thymus, and can be conceptually divided into three phases:
- A rare population of hematopoietic progenitors enters the thymus from the blood, and expands by cell division to generate a large population of immature thymocytes.
- Immature thymocytes each make distinct T cell receptors by a process of gene rearrangement. This process is error-prone, and some thymocytes fail to make functional T cell receptors, whereas other thymocytes make T cell receptors that are autoreactive. . Growth factors include thymopoietin and thymosin.
- Immature thymocytes undergo a process of selection, based on the specificity of their T cell receptors. This involves selection of T cells that are functional (positive selection), and elimination of T cells that are autoreactive (negative selection).
Cells that pass both levels of selection are released into the bloodstream to perform vital immune functions.
# Cancer
Two primary forms of tumours originate in the thymus.
Tumours originating from the thymic epithelial cells are called thymomas, and are found in about 25-50% of patients with myasthenia gravis. Symptoms are sometimes confused with bronchitis or a strong cough because the tumor presses on the cough nerve. All thymomas are potentially cancerous, but they can vary a great deal. Some grow very slowly. Others grow rapidly and can spread to surrounding tissues. Treatment of thymomas often requires surgery to remove the entire thymus.
Tumours originating from the thymocytes are called thymic lymphomas.
# X-ray
Patient #1: Radiograph demonstrates a normal thymus
Patient #2: Radiograph demonstrates the wave sign of a normal thymus
# Other animals and second thymus
The thymus is also present in most vertebrates, with similar structure and function as the human thymus. Some animals have multiple secondary (smaller) thymi in the neck, this phenomenon has been reported for mice and also occurs in 5 out of 6 human fetuses. As in humans, the Guinea pig's thymus naturally atrophies as the animal reaches adulthood, but in the hairless "Skinny pig" breed (which arose from a spontaneous laboratory mutation) it often possesses no thymic tissue whatsoever, and the organ cavity is replaced with cystic spaces.
When animal thymic tissue is sold in a butcher shop or at a meat counter, thymus is known as sweetbread. | Thymus
Template:Infobox Anatomy
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]
# Overview
In human anatomy, the thymus is an organ located in the upper anterior portion of the chest cavity just behind the sternum. Hormones produced by this organ stimulate the production of certain infection-fighting cells. It is of central importance in the maturation of T cells.
# History
Due to the large numbers of apoptotic lymphocytes, the thymus was originally dismissed as a "lymphocyte graveyard", without functional importance. The importance of the thymus in the immune system was discovered in 1961 by Jacques Miller, by surgically removing the thymus from three day old mice, and observing the subsequent deficiency in a lymphocyte population, subsequently named T cells after the organ of their origin. [1] Recently advances in immunology have allowed the fine dissection of the function of the thymus in T cell maturation.
# Development
## Embryology
The two main components of the thymus, the lymphoid thymocytes and the thymic epithelial cells, have distinct developmental origins. The thymic epithelium is the first to develop, and appears in the form of two flask-shape endodermal diverticula, which arise, one on either side, from the third branchial pouch (pharyngeal pouch), and extend lateralward and backward into the surrounding mesoderm and neural crest-derived mesenchyme in front of the ventral aorta.
Here they meet and become joined to one another by connective tissue, but there is never any fusion of the thymus tissue proper. The pharyngeal opening of each diverticulum is soon obliterated, but the neck of the flask persists for some time as a cellular cord. By further proliferation of the cells lining the flask, buds of cells are formed, which become surrounded and isolated by the invading mesoderm. Additional portions of thymus tissue are sometimes developed from the fourth branchial pouches. [2]
During the late stages of the development of the thymic epithelium, hematopoietic lymphoid cells from bone-marrow precursors immigrate into the thymus and are aggregated to form lymphoid follicles.
The thymus continues to grow between birth and puberty and then begins to atrophy, a process directed by the high levels of circulating sex hormones. Proportional to thymic size, thymic activity (T cell output) is most active before puberty. Upon atrophy, the size and activity are dramatically reduced, and the organ is primarily replaced with fat (a phenomenon known as "involution"). The atrophy is due to the increased circulating level of sex hormones, and chemical or physical castration of an adult results in the thymus increasing in size and activity. [3]
Patients with the autoimmune disease Myasthenia gravis commonly (70%) are found to have thymic hyperplasia or malignancy.[4] The reason or order of these cirumstances has yet to be determined by medical scientists.
# Anatomy
The thymus is of a pinkish-gray color, soft, and lobulated on its surfaces. At birth it is about 5 cm in length, 4 cm in breadth, and about 6 mm in thickness. The organ enlarges during childhood, and atrophies at puberty.
The thymus will, if examined when its growth is most active, be found to consist of two lateral lobes placed in close contact along the middle line, situated partly in the thorax, partly in the neck, and extending from the fourth costal cartilage upward, as high as the lower border of the thyroid gland.
It is covered by the sternum, and by the origins of the sternohyoidei and sternothyreoidei.
Below, it rests upon the pericardium, being separated from the aortic arch and great vessels by a layer of fascia.
In the neck, it lies on the front and sides of the trachea, behind the sternohyoidei and sternothyreoidei.
The two lobes generally differ in size; they are occasionally united, so as to form a single mass, and sometimes separated by an intermediate lobe.
# Structure
Each lateral lobe is composed of numerous lobules held together by delicate areolar tissue; the entire organ being enclosed in an investing capsule[5] of a similar but denser structure. The primary lobules vary in size from that of a pin's head to that of a small pea, and are made up of a number of small nodules or follicles.
The follicles are irregular in shape and are more or less fused together, especially toward the interior of the organ. Each follicle is from 1 to 2 mm in diameter and consists of a medullary and a cortical portion[6], and these differ in many essential particulars from each other.
## Cortex
The cortical portion is mainly composed of lymphoid cells, supported by a network of finely-branched epithelial reticular cells, which is continuous with a similar network in the medullary portion. This network forms an adventitia to the blood vessels.
The cortex is the location of the earliest events in thymocyte development, where T cell receptor gene rearrangement and positive selection takes place.
## Medulla
In the medullary portion, the reticulum is coarser than in the cortex, the lymphoid cells are relatively fewer in number, and there are found peculiar nest-like bodies, the concentric corpuscles of Hassall.[7] These concentric corpuscles are composed of a central mass, consisting of one or more granular cells, and of a capsule formed of epithelioid cells. They are the remains of the epithelial tubes, which grow out from the third branchial pouches of the embryo to form the thymus. Each follicle is surrounded by a vascular plexus, from which vessels pass into the interior, and radiate from the periphery toward the center, forming a second zone just within the margin of the medullary portion. In the center of the medullary portion there are very few vessels, and they are of minute size.
The medulla is the location of the latter events in thymocyte development. Thymocytes that reach the medulla have already successfully undergone T cell receptor gene rearrangement and positive selection, and have been exposed to a limited degree of negative selection. The medulla is specialised to allow thymocytes to undergo additional rounds of negative selection to remove auto-reactive T cells from the mature repertoire. The gene AIRE is expressed in the medulla, and drives the transcription of organ-specific genes such as insulin to allow maturing thymocytes to be exposed to a more complex set of self-antigens than is present in the cortex.
## Vasculature
The arteries supplying the thymus are derived from the internal mammary, and from the superior thyroid and inferior thyroids.
The veins end in the left innominate vein, and in the thyroid veins.
The nerves are exceedingly minute; they are derived from the vagi and sympathetic nervous system. Branches from the descendens hypoglossi and phrenic reach the investing capsule, but do not penetrate into the substance of the organ.
# Function
In the two thymic lobes, lymphocyte precursors from the bone-marrow become thymocytes, and subsequently mature into T cells. Once mature, T cells emigrate from the thymus and constitute the peripheral T cell repertoire responsible for directing many facets of the adaptive immune system. Loss of the thymus at an early age through genetic mutation or surgical removal results in severe immunodeficiency and a high susceptibility to infection. [8].
However up to January 2001, it was thought that whilst the thymus gland is important to the immune system in the developing foetus, the gland becomes redundant after birth, and so can be surgically excised without harm to the patient.[9]
The ability of T cells to recognize foreign antigens is mediated by the T cell receptor. The T cell receptor undergoes genetic rearrangement during thymocyte maturation, resulting in each T cell bearing a unique T cell receptor, specific to a limited set of peptide:MHC combinations. The random nature of the genetic rearrangement results in a requirement of central tolerance mechanisms to remove or inactivate those T cells which bear a T cell receptor with the ability to recognise self-peptides.
## Phases of thymocyte maturation
The generation of T cells expressing distinct T cell receptors occurs within the thymus, and can be conceptually divided into three phases:
- A rare population of hematopoietic progenitors enters the thymus from the blood, and expands by cell division to generate a large population of immature thymocytes[10].
- Immature thymocytes each make distinct T cell receptors by a process of gene rearrangement. This process is error-prone, and some thymocytes fail to make functional T cell receptors, whereas other thymocytes make T cell receptors that are autoreactive. [11]. Growth factors include thymopoietin and thymosin.
- Immature thymocytes undergo a process of selection, based on the specificity of their T cell receptors. This involves selection of T cells that are functional (positive selection), and elimination of T cells that are autoreactive (negative selection).
Cells that pass both levels of selection are released into the bloodstream to perform vital immune functions.
# Cancer
Two primary forms of tumours originate in the thymus.
Tumours originating from the thymic epithelial cells are called thymomas, and are found in about 25-50% of patients with myasthenia gravis. Symptoms are sometimes confused with bronchitis or a strong cough because the tumor presses on the cough nerve. All thymomas are potentially cancerous, but they can vary a great deal. Some grow very slowly. Others grow rapidly and can spread to surrounding tissues. Treatment of thymomas often requires surgery to remove the entire thymus.
Tumours originating from the thymocytes are called thymic lymphomas.
# X-ray
Patient #1: Radiograph demonstrates a normal thymus
-
Patient #2: Radiograph demonstrates the wave sign of a normal thymus
-
# Other animals and second thymus
The thymus is also present in most vertebrates, with similar structure and function as the human thymus. Some animals have multiple secondary (smaller) thymi in the neck, this phenomenon has been reported for mice [13] and also occurs in 5 out of 6 human fetuses.[14] As in humans, the Guinea pig's thymus naturally atrophies as the animal reaches adulthood, but in the hairless "Skinny pig" breed (which arose from a spontaneous laboratory mutation) it often possesses no thymic tissue whatsoever, and the organ cavity is replaced with cystic spaces.
When animal thymic tissue is sold in a butcher shop or at a meat counter, thymus is known as sweetbread. | https://www.wikidoc.org/index.php/Thymic | |
b7d716b54954b40c52f3d9bf14ea46a8c65b4bb8 | wikidoc | Thymol | Thymol
Thymol is a monoterpene phenol derivative of cymene, C10H13OH, isomeric with carvacrol, found in oil of thyme, and extracted as a white crystalline substance of a pleasant aromatic odor and strong antiseptic properties. It is also called "hydroxy cymene". (from Webster's 1913 dictionary)
It has been found to be useful in controlling varroa mites in bee colonies.A minor use is in bookbinding: before rebinding, books with mold damage can be sealed in bags with thymol crystals to kill fungal spores. It is also used as a preservative in halothane, an anaesthetic.
In a 1994 report released by five top cigarette companies, thymol was listed as one of 599 additives to cigarettes. It is added to improve the flavor. | Thymol
Template:Chembox new
Thymol is a monoterpene phenol derivative of cymene, C10H13OH, isomeric with carvacrol, found in oil of thyme, and extracted as a white crystalline substance of a pleasant aromatic odor and strong antiseptic properties. It is also called "hydroxy cymene". (from Webster's 1913 dictionary)
It has been found to be useful in controlling varroa mites in bee colonies.[1]A minor use is in bookbinding: before rebinding, books with mold damage can be sealed in bags with thymol crystals to kill fungal spores. It is also used as a preservative in halothane, an anaesthetic.
In a 1994 report released by five top cigarette companies, thymol was listed as one of 599 additives to cigarettes.[2] It is added to improve the flavor. | https://www.wikidoc.org/index.php/Thymol | |
0726c1c3ac46ca5350ce3d95a41b45be2234edcd | wikidoc | Timbre | Timbre
# Overview
In music, timbre (Template:PronEng, Template:IPA like timber, or Template:IPA, from Fr. timbre Template:IPA) is the quality of a musical note or sound that distinguishes different types of sound production, such as voices or musical instruments. The physical characteristics of sound that mediate the perception of timbre include spectrum and envelope. Timbre is also known in psychoacoustics as sound quality or sound color.
For example, timbre is what, with a little practice, people use to distinguish the saxophone from the trumpet in a jazz group, even if both instruments are playing notes at the same pitch and amplitude. Timbre has been called "a wastebasket category", or "the psychoacoustician's multidimensional wastebasket category" as it can denote many apparently unrelated aspects of a sound.
# History
The Chinese developed a sophisticated understanding of the musical quality of timbre during the Song Dynasty. They discovered that the timbre of string instruments could be changed depending on how the strings were touched. Strings could be plucked, brushed, hit, scraped, or rubbed to produce different sounds. The Chinese composed music on the Qin, a long, wooden board with strings. Their Qin songs emphasized the timbre, and the changes in sound could be heard throughout the song.
# Synonyms
Tone quality is used as a synonym for timbre.
Tone color is also often used as a synonym. People who experience synesthesia may see certain colors when they hear particular instruments. Helmholtz used the German Klangfarbe (tone color), and Tyndall proposed an English translation, clangtint. But both terms were disapproved of by Alexander Ellis who also discredits register and color for their pre-existing English meanings (Erickson 1975, p.7).
Colors of the optical spectrum are not generally explicitly associated with particular sounds. Rather, the sound of an instrument may be described with words like "warm" or "harsh" or other terms, perhaps suggesting that tone color has more in common with the sense of touch than of sight. However, color is often used to describe different types of noise such as pink or white. Noise color is determined by mixing together parts of the visible light spectrum that correspond to the audible sound spectrum. A 20 hertz tone is subsonic and a 20000 hertz tone is ultrasonic, so pink noise is pink because it contains loud low-frequency noise mixed with quieter broadband noise.
# American Standards Association definition
The American Standards Association defines timbre as " that attribute of sensation in terms of which a listener can judge that two sounds having the same loudness and pitch are dissimilar". A note to the 1960 definition (p.45) adds that "timbre depends primarily upon the spectrum of the stimulus, but it also depends upon the waveform, the sound pressure, the frequency location of the spectrum, and the temporal characteristics of the stimulus."
# Attributes
J.F. Schouten (1968, p.42) describes the "elusive attributes of timbre" as "determined by at least five major acoustic parameters" which Robert Erickson (1975) finds "scaled to the concerns of much contemporary music":
- The range between tonal and noiselike character.
- The spectral envelope.
- The time envelope in terms of rise, duration, and decay.
- The changes both of spectral envelope (formant-glide) and fundamental frequency (micro-intonation).
- The prefix, an onset of a sound quite dissimilar to the ensuing lasting vibration.
# Spectra
The richness of a sound or note produced by a musical instrument is sometimes described in terms of a sum of a number of distinct frequencies. The lowest frequency is called the fundamental frequency and the pitch it produces is used to name the note. For example, in western music, instruments are normally tuned to A = 440 Hz. Other significant frequencies are called overtones of the fundamental frequency, which may include harmonics and partials. Harmonics are whole number multiples of the fundamental frequency — ×2, ×3, ×4, etc. Partials are other overtones. Most western instruments produce harmonic sounds, but many instruments produce partials and inharmonic tones, such as cymbals and other non-pitched instruments.
When the orchestral tuning note is played, the sound is a combination of 440 Hz, 880 Hz, 1320 Hz, 1760 Hz and so on. The balance of the amplitudes of the different frequencies is responsible for the characteristic sound of each instrument.
The fundamental is not necessarily the strongest component of the overall sound. But it is implied by the existence of the harmonic series — the A above would be distinguishable from the one an octave below (220 Hz, 440 Hz, 660 Hz, 880 Hz) by the presence of the third harmonic, even if the fundamental were indistinct. Similarly, a pitch is often inferred from non-harmonic spectra, supposedly through a mapping process, an attempt to find the closest harmonic fit.
It is possible to add artificial 'subharmonics' to the sound using electronic effects but, again, this does not affect the naming of the note.
William Sethares (2004) wrote that just intonation and the western equal tempered scale derive from the harmonic spectra/timbre of most western instruments. Similarly the specific inharmonic timbre of Thai metallophones would produce the seven-tone near-equal temperament they do indeed employ. The five-note sometimes near-equal tempered slendro scale provides the most consonance in the combination of the inharmonic spectra of Balinese metallophones with harmonic instruments such as the stringed rebab.
# Envelope
The timbre of a sound is also greatly affected by the following aspects of its envelope: attack time and characteristics, decay, sustain, release (ADSR envelope) and transients. Thus these are all common controls on synthesizers. For instance, if one takes away the attack from the sound of a piano or trumpet, it becomes more difficult to identify the sound correctly, since the sound of the hammer hitting the strings or the first blat of the player's lips are highly characteristic of those instruments. The envelope is the overall amplitude structure of a sound, so called because the sound just "fits" inside its envelope: what this means should be clear from a time-domain display of almost any interesting sound, zoomed out enough that the entire waveform is visible.
# In music
Timbre is often cited as one of the fundamental aspects of music. Formally, timbre and other factors are usually secondary to pitch. "To a marked degree the music of Debussy elevates timbre to an unprecedented structural status; already in L'Apres-midi d'un Faune the color of flute and harp functions referentially," according to Jim Samson (1977). Surpassing Debussy is Klangfarbenmelodie and surpassing that the use of sound masses.
Erickson (ibid, p.6) gives a table of subjective experiences and related physical phenomena based on Schouten's five attributes:
Often listeners are able to identify the kind of instrument even across "conditions of changing pitch and loudness, in different environments and with different players." In the case of the clarinet, an acoustic analysis of the waveforms shows they are irregular enough to suggest three instruments rather than one. David Luce (1963, p.17) suggests that this implies "certain strong regularities in the acoustic waveform of the above instruments must exist which are invariant with respect to the above variables." However, Robert Erickson argues that there are few regularities and they do not explain our "powers of recognition and identification." He suggests the borrowing from studies of vision and visual perception the concept of subjective constancy. (Erickson 1975, p.11)
# Spelling
Though timber is accepted, the more common spelling is timbre to distinguish the word from timber ("wood"). | Timbre
# Overview
In music, timbre (Template:PronEng, Template:IPA like timber, or Template:IPA,[1] from Fr. timbre Template:IPA) is the quality of a musical note or sound that distinguishes different types of sound production, such as voices or musical instruments. The physical characteristics of sound that mediate the perception of timbre include spectrum and envelope. Timbre is also known in psychoacoustics as sound quality or sound color.
For example, timbre is what, with a little practice, people use to distinguish the saxophone from the trumpet in a jazz group, even if both instruments are playing notes at the same pitch and amplitude. Timbre has been called "a wastebasket category",[2] or "the psychoacoustician's multidimensional wastebasket category"[3] as it can denote many apparently unrelated aspects of a sound.
# History
The Chinese developed a sophisticated understanding of the musical quality of timbre during the Song Dynasty[citation needed]. They discovered that the timbre of string instruments could be changed depending on how the strings were touched. Strings could be plucked, brushed, hit, scraped, or rubbed to produce different sounds. The Chinese composed music on the Qin, a long, wooden board with strings. Their Qin songs emphasized the timbre, and the changes in sound could be heard throughout the song.
# Synonyms
Tone quality is used as a synonym for timbre.
Tone color is also often used as a synonym. People who experience synesthesia may see certain colors when they hear particular instruments. Helmholtz used the German Klangfarbe (tone color), and Tyndall proposed an English translation, clangtint. But both terms were disapproved of by Alexander Ellis who also discredits register and color for their pre-existing English meanings (Erickson 1975, p.7).
Colors of the optical spectrum are not generally explicitly associated with particular sounds. Rather, the sound of an instrument may be described with words like "warm" or "harsh" or other terms, perhaps suggesting that tone color has more in common with the sense of touch than of sight. However, color is often used to describe different types of noise such as pink or white. Noise color is determined by mixing together parts of the visible light spectrum that correspond to the audible sound spectrum. A 20 hertz tone is subsonic and a 20000 hertz tone is ultrasonic, so pink noise is pink because it contains loud low-frequency noise mixed with quieter broadband noise.
# American Standards Association definition
The American Standards Association defines timbre as "[...] that attribute of sensation in terms of which a listener can judge that two sounds having the same loudness and pitch are dissimilar". A note to the 1960 definition (p.45) adds that "timbre depends primarily upon the spectrum of the stimulus, but it also depends upon the waveform, the sound pressure, the frequency location of the spectrum, and the temporal characteristics of the stimulus."
# Attributes
J.F. Schouten (1968, p.42) describes the "elusive attributes of timbre" as "determined by at least five major acoustic parameters" which Robert Erickson (1975) finds "scaled to the concerns of much contemporary music":
- The range between tonal and noiselike character.
- The spectral envelope.
- The time envelope in terms of rise, duration, and decay.
- The changes both of spectral envelope (formant-glide) and fundamental frequency (micro-intonation).
- The prefix, an onset of a sound quite dissimilar to the ensuing lasting vibration.
# Spectra
The richness of a sound or note produced by a musical instrument is sometimes described in terms of a sum of a number of distinct frequencies. The lowest frequency is called the fundamental frequency and the pitch it produces is used to name the note. For example, in western music, instruments are normally tuned to A = 440 Hz. Other significant frequencies are called overtones of the fundamental frequency, which may include harmonics and partials. Harmonics are whole number multiples of the fundamental frequency — ×2, ×3, ×4, etc. Partials are other overtones. Most western instruments produce harmonic sounds, but many instruments produce partials and inharmonic tones, such as cymbals and other non-pitched instruments.
When the orchestral tuning note is played, the sound is a combination of 440 Hz, 880 Hz, 1320 Hz, 1760 Hz and so on. The balance of the amplitudes of the different frequencies is responsible for the characteristic sound of each instrument.
The fundamental is not necessarily the strongest component of the overall sound. But it is implied by the existence of the harmonic series — the A above would be distinguishable from the one an octave below (220 Hz, 440 Hz, 660 Hz, 880 Hz) by the presence of the third harmonic, even if the fundamental were indistinct. Similarly, a pitch is often inferred from non-harmonic spectra, supposedly through a mapping process, an attempt to find the closest harmonic fit.
It is possible to add artificial 'subharmonics' to the sound using electronic effects but, again, this does not affect the naming of the note.
William Sethares (2004) wrote that just intonation and the western equal tempered scale derive from the harmonic spectra/timbre of most western instruments. Similarly the specific inharmonic timbre of Thai metallophones would produce the seven-tone near-equal temperament they do indeed employ. The five-note sometimes near-equal tempered slendro scale provides the most consonance in the combination of the inharmonic spectra of Balinese metallophones with harmonic instruments such as the stringed rebab.
# Envelope
The timbre of a sound is also greatly affected by the following aspects of its envelope: attack time and characteristics, decay, sustain, release (ADSR envelope) and transients. Thus these are all common controls on synthesizers. For instance, if one takes away the attack from the sound of a piano or trumpet, it becomes more difficult to identify the sound correctly, since the sound of the hammer hitting the strings or the first blat of the player's lips are highly characteristic of those instruments. The envelope is the overall amplitude structure of a sound, so called because the sound just "fits" inside its envelope: what this means should be clear from a time-domain display of almost any interesting sound, zoomed out enough that the entire waveform is visible.
# In music
Timbre is often cited as one of the fundamental aspects of music. Formally, timbre and other factors are usually secondary to pitch. "To a marked degree the music of Debussy elevates timbre to an unprecedented structural status; already in L'Apres-midi d'un Faune the color of flute and harp functions referentially," according to Jim Samson (1977). Surpassing Debussy is Klangfarbenmelodie and surpassing that the use of sound masses.
Erickson (ibid, p.6) gives a table of subjective experiences and related physical phenomena based on Schouten's five attributes:
Often listeners are able to identify the kind of instrument even across "conditions of changing pitch and loudness, in different environments and with different players." In the case of the clarinet, an acoustic analysis of the waveforms shows they are irregular enough to suggest three instruments rather than one. David Luce (1963, p.17) suggests that this implies "certain strong regularities in the acoustic waveform of the above instruments must exist which are invariant with respect to the above variables." However, Robert Erickson argues that there are few regularities and they do not explain our "powers of recognition and identification." He suggests the borrowing from studies of vision and visual perception the concept of subjective constancy. (Erickson 1975, p.11)
# Spelling
Though timber is accepted, the more common spelling is timbre to distinguish the word from timber ("wood"). | https://www.wikidoc.org/index.php/Timbre | |
2d77a6a027021a3902b13d0aea104b4f4b3e66e1 | wikidoc | Tomato | Tomato
The tomato (Solanum lycopersicum) is a plant in the Solanaceae or nightshade family, as are its close cousins tobacco, chili peppers, potato, and eggplant. The tomato is native to Central, South, and southern North America from Mexico to Peru. It is a perennial, often grown outdoors in temperate climates as an annual, typically reaching to 1–3 m (3 to 10 ft) in height, with a weak, woody stem that often vines over other plants.
The leaves are 10–25 cm long, pinnate, with 5–9 leaflets, each leaflet up to 8 cm long, with a serrated margin; both the stem and leaves are densely glandular-hairy. The flowers are 1–2 cm across, yellow, with five pointed lobes on the corolla; they are borne in a cyme of 3–12 together.
The word tomato derives from a word in the Nahuatl language, tomatl. The specific name, lycopersicum, means "wolf-peach" (compare the related species S. lycocarpum, whose scientific name means "wolf-fruit", common name "wolf-apple").
# History and distribution
## Early history
According to Andrew F Smith's The Tomato in America, the tomato probably originated in the highlands of the west coast of South America. Smith notes there is no evidence the tomato was cultivated or even eaten before the Spanish arrived. Other researchers, however, have pointed out that this is not conclusive, as many other fruits in continuous cultivation in Peru are not present in the very limited historical record. Much horticultural knowledge was lost after the arrival of Europeans.
There is a competing theory that says the tomato, like the word "tomato", originated in Mexico, where one of the two apparently oldest "wild" types grows. It is entirely possible that domestication even arose in both regions independently.
In any case, by some means the tomato migrated to Central America. Maya and other peoples in the region used the fruit in their cooking, and it was being cultivated in southern Mexico and probably other areas, by the 16th century. It is thought that the Pueblo people believed those who witnessed the ingestion of tomato seeds were blessed with powers of divination. The large, lumpy tomato, a mutation from a smoother, smaller fruit, originated and was encouraged in Central America. Smith states this variant is the direct ancestor of some modern cultivated tomatoes.
Two modern tomato cultivar groups, one represented by the Matt's Wild Cherry tomato, the other by currant tomatoes, both originate by recent domestication of the wild tomato plants apparently native to
## Spanish distribution
After the Spanish colonization of the Americas, the Spanish distributed the tomato throughout their colonies in the Caribbean. They also took it to the Philippines, whence it moved to southeast Asia and then the entire Asian continent. The Spanish also brought the tomato to Europe. It grew easily in Mediterranean climates, and cultivation began in the 1540s. It was probably eaten shortly after it was introduced, though it was certainly being used as food by the early 1600s in Spain. The earliest discovered cookbook with tomato recipes was published in Naples in 1692, though the author had apparently obtained these recipes from Spanish sources.
## Tomatoes in Britain
The tomato plant was not grown in England until the 1590s, according to Smith. One of the earliest cultivators was John Gerard, a barber-surgeon. Gerard's Herbal, published in 1597 and largely plagiarized from continental sources, is also one of the earliest discussions of the tomato in England. Gerard knew that the tomato was eaten in both Spain and Italy. Nonetheless, he believed that it was poisonous (tomato leaves and stems contain poisonous glycoalkaloids, but the fruit is safe). Gerard's views were influential, and the tomato was considered unfit for eating (though not necessarily poisonous) for many years in Britain and its North American colonies. By the mid-1700s, however, tomatoes were widely eaten in Britain; and before the end of that century, the Encyclopædia Britannica stated that the tomato was "in daily use" in soups, broths, and as a garnish.
In Victorian times, cultivation reached an industrial scale in glasshouses, most famously in Worthing. Pressure for housing land in the 1930s to 1960s saw the industry move west to Littlehampton, and to the market gardens south of Chichester.
The British tomato industry has been decimated over the past fifteen years or so as cheap imports from Spain have flooded the supermarkets.
## North America
The earliest reference to tomatoes being grown in British North America is from 1710, when herbalist William Salmon reported seeing them in what is today South Carolina. They may have been introduced from the Caribbean. By the mid-18th century, they were cultivated on some Carolina plantations, and probably in other parts of the South as well. It is possible that some people continued to think tomatoes were poisonous at this time; and in general, they were grown more as ornamental plants than as food. Cultured people like Thomas Jefferson, who ate tomatoes in Paris and sent some seeds home, knew the tomato was edible, but many of the less well-educated did not.
## Tomatoes in France
The tomato was introduced to France through Provence from Italy during the late 18th century and became a culinary symbol of the French Revolution due to its red color. They are widely eaten in French cuisine.
## Production trends
125 million tonnes of tomatoes were produced in the world in 2005, with China, the largest producer, accounting for about one-fourth of the global output followed by United States and Turkey.
According to FAOSTAT, the top producers of tomatoes (in tonnes) in 2005 were:
# Cultivation and uses
The tomato is now grown worldwide for its edible fruits, with thousands of cultivars having been selected with varying fruit types, and for optimum growth in differing growing conditions. Cultivated tomatoes vary in size from cherry tomatoes, about the same 1–2 cm size as the wild tomato, up to beefsteak tomatoes 10 cm or more in diameter. The most widely grown commercial tomatoes tend to be in the 5–6 cm diameter range. Most cultivars produce red fruit; but a number of cultivars with yellow, orange, pink, purple, green, or white fruit are also available. Multicolored and striped fruit can also be quite striking. Tomatoes grown for canning are often elongated, 7–9 cm long and 4–5 cm diameter; they are known as plum tomatoes.
Tomatoes are one of the most common garden fruits in the United States and, along with zucchini, have a reputation for outproducing the needs of the grower.
As in most sectors of agriculture, there is increasing demand in developed countries for organic tomatoes, as well as heirloom tomatoes, to make up for flavor and texture faults in commercial tomatoes. Quite a few seed merchants and banks provide a large selection of heirloom seeds. Tomato seeds are occasionally organically produced as well, but only a small percentage of organic crop area is grown with organic seed.
## Growing needs
For information on growing tomatoes, please see the relevant chapter in A Wikimanual of Gardening, and/or WikiHow: to Grow a Tomato Plant.
## Cultivars
There are a great many tomato cultivars grown for various purposes. Heirloom cultivars are becoming increasingly popular, particularly among home gardeners and organic producers, since they tend to produce more interesting and flavorful crops at the possible cost of some disease resistance. Hybrid plants remain common, since they tend to be heavier producers and sometimes combine unusual characteristics of heirloom tomatoes with the ruggedness of conventional commercial tomatoes.
Tomato cultivars are roughly divided into several categories, based mostly on shape and size. "Slicing" or "globe" tomatoes are the usual tomatoes of commerce; beefsteak are large tomatoes often used for sandwiches and similar applications - their kidney-bean shape makes commercial use impractical; oxheart tomatoes can range in size up to beefsteaks, and are shaped like large strawberries; plum tomatoes, or paste tomatoes, are bred with a higher solid content for use in tomato sauce and paste and are usually oblong shaped; cherry tomatoes are small and round, often sweet tomatoes generally eaten whole in salads; and grape tomatoes are smaller and oblong or pear-shaped, also used in salads.
Tomatoes are also commonly classified as determinate or indeterminate. Determinate, or bush, types bear a full crop all at once and top off at a specific height; they are often good choices for container growing. Determinate types are preferred by commercial growers who wish to harvest a whole field at one time, or home growers interested in canning. Indeterminate cultivars develop into vines that never top off and continue producing until killed by frost. They are preferred by home growers who wish ripe fruit throughout the season. As an intermediate form, there are plants sometimes known as "vigorous determinate" or "semi-determinate"; these top off like determinates but produce a second crop after the initial crop. Many, if not all, heirloom tomatoes are indeterminate.
Commonly grown cultivars include:
- 'Beefsteak VFN' (a common hybrid resistant to Verticillium, Fusarium, and Nematodes)
- 'Big Boy' (a very common determinate garden cultivar in the United States)
- 'Black Krim' (a purple-and-red cultivar from the Crimea)
- 'Brandywine' (a pink, indeterminate beefsteak type with a considerable number of substrains)
- 'Burpee VF' (an early attempt by W. Atlee Burpee at disease resistance in a commercial tomato)
- 'Early Girl' (an early maturing globe type)
- 'Gardener's Delight' (a smaller English cultivar)
- 'Juliet' (a grape tomato developed as a substitute for the rare Santa F1)
- 'Marmande' (a heavily ridged cultivar from southern France; similar to a small beefsteak and available commercially in the U.S. as UglyRipe)
- 'Moneymaker' (an English greenhouse cultivar)
- Mortgage Lifter (a popular heirloom beefsteak known for gigantic fruit)
- 'Patio' (bred specifically for container gardens)
- 'Purple Haze' (large cherry, indeterminate. Derived from Cherokee Purple, Brandywine and Black Cherry)
- 'Roma VF' (a plum tomato common in supermarkets)
- 'Rutgers' (a commercial heirloom cultivar)
- 'San Marzano' (a plum tomato popular in Italy)
- 'Santa F1' (a Chinese grape tomato cultivar popular in the U.S. and parts of southeast Asia)
- 'Shephard's Sack' (a large variety popular in parts of Wales)
- 'Sweet 100' (a very prolific, indeterminate cherry tomato)
- 'Yellow Pear' (a yellow, pear-shaped heirloom cultivar)
Home Cultivars with exceptional taste include:
- 'Andrew Rahart Jumbo Red' (red beefsteak)
- 'Black Cherry' (black/brown cherry)
- 'Box Car Willie' (red beefsteak)
- 'Brandywine' (red beefsteak, Sudduth strain)
- 'Cherokee Purple' (purple beefsteak)
- 'Crnkovic Yugoslavian' (red beefsteak)
- 'Earl’s Faux' (pink/red beefsteak)
- 'Elbe' (orange beefsteak)
- 'Great Divide' (red beefsteak)
- 'Lucky Cross' (bi-color red/orange)
- 'Marianna’s Peace' (red beefsteak)
- 'Mortgage Lifter' (red beefsteak, various strains)
- 'Sungold' (orange cherry, not open pollinated)
An excellent source for additional varieties of homegrown cultivars is the Seed Savers Exchange.
Most modern tomato cultivars are smooth surfaced but some older tomato cultivars and most modern beefsteaks often show pronounced ribbing, a feature that may have been common to virtually all pre-Columbian cultivars. In addition, some tomato cultivars produce fruit in colors other than red, including yellow, orange, pink, black, brown, and purple, though such fruit is not widely available in grocery stores, nor are their seedlings available in typical nurseries, but must be bought as seed, often via mail-order. Likewise, some less common varieties have fuzzy skin on the fruit, as is the case with the Fuzzy Peach tomato and Red Boar tomato plants.
There is also a considerable gap between commercial and home-gardener cultivars; home cultivars are often bred for flavor to the exclusion of all other qualities, while commercial cultivars are bred for such factors as consistent size and shape, disease and pest resistance, and suitability for mechanized picking and shipping.
## Diseases and pests
Tomato cultivars vary widely in their resistance to disease. Modern hybrids focus on improving disease resistance over the heirloom plants. One common tomato disease is tobacco mosaic virus, and for this reason smoking or use of tobacco products are discouraged around tomatoes, although there is some scientific debate over whether the virus could possibly survive being burned and converted into smoke. Various forms of mildew and blight are also common tomato afflictions, which is why tomato cultivars are often marked with a combination of letters which refer to specific disease resistance. The most common letters are: V - verticillium wilt, F - fusarium wilt strain I, FF - fusarium wilt strain I & II, N - nematodes, T - tobacco mosaic virus, and A - alternaria.
Another particularly dreaded disease is curly top, carried by the beet leafhopper, which interrupts the lifecycle, ruining a nightshade plant as a crop. As the name implies, it has the symptom of making the top leaves of the plant wrinkle up and grow abnormally.
Some common tomato pests are cutworms, tomato hornworms and tobacco hornworms, aphids, cabbage loopers, whiteflies, tomato fruitworms, flea beetles, red spider mite, slugs, and Colorado potato beetles.
## Pollination
In the wild, original state, tomatoes required cross-pollination; they were much more self-incompatible than domestic cultivars. As a floral device to reduce selfing, the pistils of wild tomatoes extended farther out of the flower than today's cultivars. The stamens were, and remain, entirely within the closed corolla.
As tomatoes were moved from their native areas, their traditional pollinators, (probably a species of halictid bee) did not move with them. The trait of self-fertility (or self-pollenizing) became an advantage and domestic cultivars of tomato have been selected to maximize this trait.
This is not the same as self-pollination, despite the common claim that tomatoes do so. That tomatoes pollinate themselves poorly without outside aid is clearly shown in greenhouse situations where pollination must be aided by artificial wind, vibration of the plants (one brand of vibrator is a wand called an "electric bee" that is used manually), or more often today, by cultured bumblebees.
The anther of a tomato flower is shaped like a hollow tube, with the pollen produced within the structure rather than on the surface, as with most species. The pollen moves through pores in the anther, but very little pollen is shed without some kind of outside motion.
The best source of outside motion is a sonicating bee such as a bumblebee or the original wild halictid pollinator. In an outside setting, wind or biological agents provide sufficient motion to produce commercially viable crops.
## Hydroponic and greenhouse cultivation
Tomatoes are often grown in greenhouses in cooler climates, and indeed there are cultivars such as the British 'Moneymaker' and a number of cultivars grown in Siberia that are specifically bred for indoor growing. In more temperate climates, it is not uncommon to start seeds in greenhouses during the late winter for future transplant. With the transplanting of tomatoes, there is a process of hardening that the plant must go through before being able to be placed outside in order to have greater survival.
Hydroponic tomatoes are also available, and the technique is often used in hostile growing environments as well as high-density plantings.
## Picking and ripening
Tomatoes are often picked unripe (and thus green) and ripened in storage with ethylene. Ethylene is a hydrocarbon gas produced by many fruits that acts as the molecular cue to begin the ripening process. Tomatoes ripened in this way tend to keep longer but have poorer flavor and a mealier, starchier texture than tomatoes ripened on the plant. They may be recognized by their color, which is more pink or orange than the other ripe tomatoes' deep red.
In 1994 Calgene introduced a genetically modified tomato called the 'FlavrSavr' which could be vine ripened without compromising shelf life. However, the product was not commercially successful (see main article for details) and was only sold until 1997.
Recently, stores have begun selling "tomatoes on the vine", which are determinate varieties that are ripened or harvested with the fruits still connected to a piece of vine. These tend to have more flavor than artificially ripened tomatoes (at a price premium), but still may not be the equal of local garden produce.
Slow-ripening cultivars of tomato have been developed by crossing a non-ripening cultivar with ordinary tomato cultivars. Cultivars were selected whose fruits have a long shelf life and at least reasonable flavor.
## Modern uses of tomatoes
Tomatoes are now eaten freely throughout the world, and their consumption is believed to benefit the heart among other things. Lycopene, one of nature's most powerful antioxidants, is present in tomatoes, and, especially when tomatoes are cooked, has been found beneficial in preventing prostate cancer. However, other research contradicts this claim. Tomato extract branded as Lycomato is now also being promoted for treatment of high blood pressure.
Though it is botanically a fruit, the tomato is nutritionally categorized as a vegetable (see below). Since "vegetable" is not a botanical term, there is no contradiction in a plant part being a fruit botanically while still being considered a vegetable.
Tomatoes are used extensively in Mediterranean and Middle Eastern cuisine, with Italian being the most notable. The tomato has an acidic property that is used to bring out other flavors. This same acidity makes tomatoes especially easy to preserve in home canning as tomato sauce or paste. The first to commercially can tomatoes was Harrison Woodhull Crosby in Jamesburg, New Jersey. Tomato juice is often canned and sold as a beverage. Unripe green tomatoes can also be used to make salsa, be breaded and fried, or pickled.
The town of Buñol, Spain, annually celebrates La Tomatina, a festival centered on an enormous tomato fight. Tomatoes are also a popular "non-lethal" throwing weapon in mass protests; and there is a common tradition of throwing rotten tomatoes at bad performers on a stage, although this tradition is more symbolic today. Embracing it for this protest connotation, the Dutch Socialist party adopted the tomato as their logo.
Known for its tomato growth and production, the Mexican state of Sinaloa takes the tomato as its symbol.
Culinary uses of tomatoes include:
- Tomato paste
- Tomato purée
- Tomato pie
- Gazpacho (Andalusian cuisine)
- Ketchup
- Pa amb tomàquet (Catalan cuisine)
- Pizza
- Tomato sauce (common in Italian cuisine)
## Storage
Most tomatoes today are picked before fully ripe. They are bred to continue ripening, but the enzyme that ripens tomatoes stops working when it reaches temperatures below 12.5 °C (54.5 °F). Once an unripe tomato drops below that temperature, it will not continue to ripen. Once fully ripe, tomatoes can be stored in the refrigerator but are best kept and eaten at room temperature. Tomatoes stored in the refrigerator tend to lose flavor, but will still be edible; thus the "Never Refrigerate" stickers sometimes placed on tomatoes in supermarkets.
# Botanical Description
Tomato plants are vines, initially decumbent, typically growing six feet or more above the ground if supported, although erect bush varieties have been bred, generally three feet tall or shorter. It is a "tender" perennial, dying annually in temperate climates (to which it is not native). Tomato plants are dicots, and grow as a series of branching stems, with a terminal bud at the tip that does the actual growing. When that tip eventually stops growing, whether because of pruning or flowering, lateral buds take over and grow into other, fully functional, vines.
Tomato plant vines are typically pubescent, covered with tiny hairs. These hairs facilitate the vining process, turning into roots wherever the plant is in contact with the ground and moisture, especially if there is some issue with the vine's contact to its original root.
Tomato plants generally have compound leaves, known as Regular Leaf (RL) plants. Some cultivars, though, have simple leaves known as potato leaf style because of their resemblance to that close cousin. Of regular leaf varieties, there are variations, such as rugose leaves, which are deeply grooved, angora leaves, which are pubescent (hairy), and variegated, which have additional colors where a genetic flaw excludes chlorophyll from the leaves.
Their flowers, appearing on the apical meristem, have the anthers fused along the edges, forming a column surrounded by the pistil's style. These tend to be self-fertilizing. This is because they are native to the Americas; all plants from the New World evolved without honeybees (which are native to the old world, only), and have other specific means of fertilization.
Its fruit is classified, botanically, as a berry. As a true fruit, it develops from the ovary of the plant after fertilization, its flesh comprising the pericarp walls. The fruit contains hollow spaces full of seeds and moisture, called locular cavities. These vary, among cultivated species, according to type. Some smaller tomatoes have two cavities, globe-shaped typically have three to five, and beefsteak having a great number of smaller ones, while paste tomatoes have very few, very small cavities.
The seeds need to come from a mature fruit, and be dried/fermented before germination.
# Myths of the tomato
There are many legends about the tomato. For example, it has been claimed that tomatoes were not widely eaten in the U.S. until the late 1800s. It has sometimes been claimed that tomatoes were considered aphrodisiacs and so were shunned by the Puritans. Other claims center on the supposed fear that tomatoes were poisonous, based on the fact that they belong to the Solanales Order, or "Nightshade" family, which contains many toxic plants. Many legends also maintain that the tomato was introduced into the U.S. from South America by one particular person; Thomas Jefferson is sometimes mentioned.
Tomatoes' status as an aphrodisiac may be due to a mistranslation. Legend has it a Frenchman on his travels ate a meal with tomatoes in it and was fascinated with the new taste. He went back to the chef, who was Italian, and asked him what this new ingredient was. The chef said "Pomme de Maure" (Apple of the Moors), but the Frenchman misunderstood and thought he said "Pomme d'amour" (apple of love). The modern Italian word for tomato is "pomodoro."
In the United States, the most famous legend of this sort was introduced by Joseph S. Sickler in the mid-1900s, and became the subject of a CBS broadcast of You Are There in 1949. The story goes that the lingering doubts about the safety of the tomato in the United States were largely put to rest in 1820, when Colonel Robert Gibbon Johnson announced that at noon on September 26, he would eat a basket of tomatoes in front of the Salem, New Jersey courthouse. Reportedly, a crowd of more than 2,000 persons gathered in front of the courthouse to watch the poor man die after eating the poisonous fruits, and were shocked when he lived. In his book Smith notes that there is little, if any, historical evidence for any of these legends, and that they continue to be repeated largely because they are entertaining stories.
It is also said that the tomato became popular in France during the French Revolution, because the revolutionaries' iconic color was red; and at one point it was suggested that they should eat red food as a show of loyalty. Since European royalty was still leery of the nightshade-related tomato, it apparently was the perfect choice. This may also be why the first reported use of the tomato in the U.S. was in New Orleans, Louisiana in 1812, because of the French influence in that region.
There is also a story which claims that an agent for Britain attempted to kill General George Washington by feeding him a dish laced with tomatoes during the American Revolution.
"Tomato" also has been used as a slang word for an attractive woman. This use was most common from the 1920s through the 1940s and only within the USA.
# Controversies
## Botanical classification
In 1753 the tomato was placed in the genus Solanum by Linnaeus as Solanum lycopersicum L. (derivation, 'lyco', wolf, plus 'persicum', peach, i.e., "wolf-peach"). However, in 1768 Philip Miller placed it in its own genus, and he named it Lycopersicon esculentum. This name came into wide use but was in breach of the plant naming rules. Technically, the combination Lycopersicon lycopersicum (L.) H.Karst. would be more correct, but this name (published in 1881) has hardly ever been used. Therefore, it was decided to conserve the well-known Lycopersicon esculentum, making this the correct name for the tomato when it is placed in the genus Lycopersicon.
However, genetic evidence (e.g., Peralta & Spooner 2001) has now shown that Linnaeus was correct in the placement of the tomato in the genus Solanum, making the Linnaean name correct; if Lycopersicon is excluded from Solanum, Solanum is left as a paraphyletic taxon. Despite this, it is likely that the exact taxonomic placement of the tomato will be controversial for some time to come, with both names found in the literature.
The Boyce Thompson Institute for Plant Research began sequencing the tomato genome in 2004 and is creating a database of genomic sequences and information on the tomato and related plants. A draft version of the full genome expected to be published by 2008. The genomes of its organelles (mitochondria and chloroplast) are also expected to be published as part of the project.
## Fruit or vegetable?
Botanically, a tomato is the ovary, together with its seeds, of a flowering plant: a fruit or, more precisely, a berry. However, the tomato is not as sweet as those foodstuffs usually called fruits and, from a culinary standpoint, it is typically served as part of a salad or main course of a meal, as are vegetables, rather than at dessert, as are fruits. As noted above, the term "vegetable" has no botanical meaning and is purely a culinary term.
This argument has had legal implications in the United States. In 1887, U.S. tariff laws that imposed a duty on vegetables but not on fruits caused the tomato's status to become a matter of legal importance. The U.S. Supreme Court settled the controversy in 1893 by declaring that the tomato is a vegetable, based on the popular definition that classifies vegetables by use, that they are generally served with dinner and not dessert (Nix v. Hedden (149 U.S. 304)). The holding of the case applies only to the interpretation of the Tariff Act of March 3, 1883, and the court did not purport to reclassify the tomato for botanical or other purposes other than paying a tax under a tariff act.
The tomato has been designated the state vegetable of New Jersey. Arkansas took both sides by declaring the "South Arkansas Vine Ripe Pink Tomato" to be both the state fruit and the state vegetable in the same law, citing both its botanical and culinary classifications. In 2006, the Ohio House of Representatives passed a law that would have declared the tomato to be the official state fruit, but the bill died when the Ohio Senate failed to act on it. Tomato juice has been the official beverage of Ohio since 1965. A.W. Livingston, of Reynoldsburg, Ohio played a large part in popularizing the tomato in the late 1800's.
But due to the scientific definition of a fruit, the tomato remains a fruit when not dealing with US tariffs. Nor is it the only culinary vegetable that is a botanical fruit: eggplants, cucumbers, and squashes of all kinds (such as zucchini and pumpkins) share the same ambiguity.
## Pronunciation
The pronunciation of tomato differs in different English-speaking countries; the two most common variants are Template:IPA and Template:IPA. Speakers from the British Isles, most of the Commonwealth, and older generations among speakers of Southern American English typically say Template:IPA, while most American and Canadian speakers usually say Template:IPA. Most or all languages, apart from American English, have a word that corresponds more to the former pronunciation, including the original Nahuatl word from which they are all taken.
The word's dual pronunciations were immortalized in Ira and George Gershwin's 1937 song "Let's Call the Whole Thing Off" (You like Template:IPA and I like Template:IPA / You like Template:IPA and I like Template:IPA) and have become a symbol for nitpicking pronunciation disputes. In this capacity it has even become an American slang term: saying Template:IPA when presented with two choices can mean "What's the difference?" or "It's all the same to me."
## Safety
On October 30, 2006 the U.S. Centers for Disease Control and Prevention (CDC) announced that tomatoes might be the source of a salmonella outbreak causing 172 illnesses in 18 states . The affected states include Arkansas, Connecticut, Georgia, Indiana, Kentucky, Maine, Massachusetts, Michigan, Minnesota, North Carolina, New Hampshire, Ohio, Pennsylvania, Rhode Island, Tennessee, Virginia, Vermont and Wisconsin. Tomatoes have been linked to seven salmonella outbreaks since 1990 (from the Food Safety Network).
# Tomato records
The heaviest tomato ever was one of 3.51 kg (7 lb 12 oz), of the cultivar 'Delicious', grown by Gordon Graham of Edmond, Oklahoma in 1986. The largest tomato plant grown was of the cultivar 'Sungold' and reached 19.8 m (65 ft) length, grown by Nutriculture Ltd (UK) of Mawdesley, Lancashire, UK, in 2000.
The massive "tomato tree" growing inside the Walt Disney World Resort's experimental greenhouses in Lake Buena Vista, Florida may be the largest single tomato plant in the world. The plant has been recognized as a Guinness World Record Holder, with a harvest of more than 32,000 tomatoes and a total weight of 1,151.84 pounds. This one-of-a-kind plant yields thousands of tomatoes at one time from a single vine. Yong Huang, Epcot's manager of agricultural science discovered the unique plant in Beijing, China. Huang brought its seeds to Epcot and created the specialized greenhouse for the fruit to grow. The vine grows golf ball-sized tomatoes which are served at Walt Disney World restaurants. The world record-setting tomato tree can be seen by guests along the Living With the Land boat ride at Epcot.
Tomatina Festival
On August 30, 2007, 40,000 Spaniards gathered in Buñol to throw 115,000 kilograms of tomatoes at each other in the yearly Tomatina festival. Bare-chested tourists also included hundreds of British, French and Germans. | Tomato
Template:Nutritionalvalue
The tomato (Solanum lycopersicum) is a plant in the Solanaceae or nightshade family, as are its close cousins tobacco, chili peppers, potato, and eggplant. The tomato is native to Central, South, and southern North America from Mexico to Peru. It is a perennial, often grown outdoors in temperate climates as an annual, typically reaching to 1–3 m (3 to 10 ft) in height, with a weak, woody stem that often vines over other plants.
The leaves are 10–25 cm long, pinnate, with 5–9 leaflets, each leaflet up to 8 cm long, with a serrated margin; both the stem and leaves are densely glandular-hairy. The flowers are 1–2 cm across, yellow, with five pointed lobes on the corolla; they are borne in a cyme of 3–12 together.
The word tomato derives from a word in the Nahuatl language, tomatl. The specific name, lycopersicum, means "wolf-peach" (compare the related species S. lycocarpum, whose scientific name means "wolf-fruit", common name "wolf-apple").
# History and distribution
## Early history
According to Andrew F Smith's The Tomato in America,[1] the tomato probably originated in the highlands of the west coast of South America. Smith notes there is no evidence the tomato was cultivated or even eaten before the Spanish arrived. Other researchers, however, have pointed out that this is not conclusive, as many other fruits in continuous cultivation in Peru are not present in the very limited historical record. Much horticultural knowledge was lost after the arrival of Europeans.
There is a competing theory that says the tomato, like the word "tomato", originated in Mexico, where one of the two apparently oldest "wild" types grows. It is entirely possible that domestication even arose in both regions independently.
In any case, by some means the tomato migrated to Central America. Maya and other peoples in the region used the fruit in their cooking, and it was being cultivated in southern Mexico and probably other areas, by the 16th century. It is thought that the Pueblo people believed those who witnessed the ingestion of tomato seeds were blessed with powers of divination. The large, lumpy tomato, a mutation from a smoother, smaller fruit, originated and was encouraged in Central America. Smith states this variant is the direct ancestor of some modern cultivated tomatoes.
Two modern tomato cultivar groups, one represented by the Matt's Wild Cherry tomato, the other by currant tomatoes, both originate by recent domestication of the wild tomato plants apparently native to
## Spanish distribution
After the Spanish colonization of the Americas, the Spanish distributed the tomato throughout their colonies in the Caribbean. They also took it to the Philippines, whence it moved to southeast Asia and then the entire Asian continent. The Spanish also brought the tomato to Europe. It grew easily in Mediterranean climates, and cultivation began in the 1540s. It was probably eaten shortly after it was introduced, though it was certainly being used as food by the early 1600s in Spain. The earliest discovered cookbook with tomato recipes was published in Naples in 1692, though the author had apparently obtained these recipes from Spanish sources.
## Tomatoes in Britain
The tomato plant was not grown in England until the 1590s, according to Smith. One of the earliest cultivators was John Gerard, a barber-surgeon. Gerard's Herbal, published in 1597 and largely plagiarized from continental sources, is also one of the earliest discussions of the tomato in England. Gerard knew that the tomato was eaten in both Spain and Italy. Nonetheless, he believed that it was poisonous (tomato leaves and stems contain poisonous glycoalkaloids, but the fruit is safe). Gerard's views were influential, and the tomato was considered unfit for eating (though not necessarily poisonous) for many years in Britain and its North American colonies. By the mid-1700s, however, tomatoes were widely eaten in Britain; and before the end of that century, the Encyclopædia Britannica stated that the tomato was "in daily use" in soups, broths, and as a garnish.
In Victorian times, cultivation reached an industrial scale in glasshouses, most famously in Worthing. Pressure for housing land in the 1930s to 1960s saw the industry move west to Littlehampton, and to the market gardens south of Chichester.
The British tomato industry has been decimated over the past fifteen years or so as cheap imports from Spain have flooded the supermarkets.
## North America
The earliest reference to tomatoes being grown in British North America is from 1710, when herbalist William Salmon reported seeing them in what is today South Carolina. They may have been introduced from the Caribbean. By the mid-18th century, they were cultivated on some Carolina plantations, and probably in other parts of the South as well. It is possible that some people continued to think tomatoes were poisonous at this time; and in general, they were grown more as ornamental plants than as food. Cultured people like Thomas Jefferson, who ate tomatoes in Paris and sent some seeds home, knew the tomato was edible, but many of the less well-educated did not.
## Tomatoes in France
The tomato was introduced to France through Provence from Italy during the late 18th century and became a culinary symbol of the French Revolution due to its red color. They are widely eaten in French cuisine.
## Production trends
125 million tonnes of tomatoes were produced in the world in 2005, with China, the largest producer, accounting for about one-fourth of the global output followed by United States and Turkey.
According to FAOSTAT, the top producers of tomatoes (in tonnes) in 2005 were:
# Cultivation and uses
The tomato is now grown worldwide for its edible fruits, with thousands of cultivars having been selected with varying fruit types, and for optimum growth in differing growing conditions. Cultivated tomatoes vary in size from cherry tomatoes, about the same 1–2 cm size as the wild tomato, up to beefsteak tomatoes 10 cm or more in diameter. The most widely grown commercial tomatoes tend to be in the 5–6 cm diameter range. Most cultivars produce red fruit; but a number of cultivars with yellow, orange, pink, purple, green, or white fruit are also available. Multicolored and striped fruit can also be quite striking. Tomatoes grown for canning are often elongated, 7–9 cm long and 4–5 cm diameter; they are known as plum tomatoes.
Tomatoes are one of the most common garden fruits in the United States and, along with zucchini, have a reputation for outproducing the needs of the grower.
As in most sectors of agriculture, there is increasing demand in developed countries for organic tomatoes, as well as heirloom tomatoes, to make up for flavor and texture faults in commercial tomatoes. Quite a few seed merchants and banks provide a large selection of heirloom seeds. Tomato seeds are occasionally organically produced as well, but only a small percentage of organic crop area is grown with organic seed.
## Growing needs
For information on growing tomatoes, please see the relevant chapter in A Wikimanual of Gardening, and/or WikiHow: to Grow a Tomato Plant.
## Cultivars
There are a great many tomato cultivars grown for various purposes. Heirloom cultivars are becoming increasingly popular, particularly among home gardeners and organic producers, since they tend to produce more interesting and flavorful crops at the possible cost of some disease resistance. Hybrid plants remain common, since they tend to be heavier producers and sometimes combine unusual characteristics of heirloom tomatoes with the ruggedness of conventional commercial tomatoes.
Tomato cultivars are roughly divided into several categories, based mostly on shape and size. "Slicing" or "globe" tomatoes are the usual tomatoes of commerce; beefsteak are large tomatoes often used for sandwiches and similar applications - their kidney-bean shape makes commercial use impractical; oxheart tomatoes can range in size up to beefsteaks, and are shaped like large strawberries; plum tomatoes, or paste tomatoes, are bred with a higher solid content for use in tomato sauce and paste and are usually oblong shaped; cherry tomatoes are small and round, often sweet tomatoes generally eaten whole in salads; and grape tomatoes are smaller and oblong or pear-shaped, also used in salads.
Tomatoes are also commonly classified as determinate or indeterminate. Determinate, or bush, types bear a full crop all at once and top off at a specific height; they are often good choices for container growing. Determinate types are preferred by commercial growers who wish to harvest a whole field at one time, or home growers interested in canning. Indeterminate cultivars develop into vines that never top off and continue producing until killed by frost. They are preferred by home growers who wish ripe fruit throughout the season. As an intermediate form, there are plants sometimes known as "vigorous determinate" or "semi-determinate"; these top off like determinates but produce a second crop after the initial crop. Many, if not all, heirloom tomatoes are indeterminate.
Commonly grown cultivars include:
- 'Beefsteak VFN' (a common hybrid resistant to Verticillium, Fusarium, and Nematodes)
- 'Big Boy' (a very common determinate garden cultivar in the United States)
- 'Black Krim' (a purple-and-red cultivar from the Crimea)
- 'Brandywine' (a pink, indeterminate beefsteak type with a considerable number of substrains)
- 'Burpee VF' (an early attempt by W. Atlee Burpee at disease resistance in a commercial tomato)
- 'Early Girl' (an early maturing globe type)
- 'Gardener's Delight' (a smaller English cultivar)
- 'Juliet' (a grape tomato developed as a substitute for the rare Santa F1)
- 'Marmande' (a heavily ridged cultivar from southern France; similar to a small beefsteak and available commercially in the U.S. as UglyRipe)
- 'Moneymaker' (an English greenhouse cultivar)
- Mortgage Lifter (a popular heirloom beefsteak known for gigantic fruit)
- 'Patio' (bred specifically for container gardens)
- 'Purple Haze' (large cherry, indeterminate. Derived from Cherokee Purple, Brandywine and Black Cherry)
- 'Roma VF' (a plum tomato common in supermarkets)
- 'Rutgers' (a commercial heirloom cultivar)
- 'San Marzano' (a plum tomato popular in Italy)
- 'Santa F1' (a Chinese grape tomato cultivar popular in the U.S. and parts of southeast Asia)
- 'Shephard's Sack' (a large variety popular in parts of Wales)
- 'Sweet 100' (a very prolific, indeterminate cherry tomato)
- 'Yellow Pear' (a yellow, pear-shaped heirloom cultivar)
Home Cultivars with exceptional taste include:
- 'Andrew Rahart Jumbo Red' (red beefsteak)
- 'Black Cherry' (black/brown cherry)
- 'Box Car Willie' (red beefsteak)
- 'Brandywine' (red beefsteak, Sudduth strain)
- 'Cherokee Purple' (purple beefsteak)
- 'Crnkovic Yugoslavian' (red beefsteak)
- 'Earl’s Faux' (pink/red beefsteak)
- 'Elbe' (orange beefsteak)
- 'Great Divide' (red beefsteak)
- 'Lucky Cross' (bi-color red/orange)
- 'Marianna’s Peace' (red beefsteak)
- 'Mortgage Lifter' (red beefsteak, various strains)
- 'Sungold' (orange cherry, not open pollinated)
An excellent source for additional varieties of homegrown cultivars is the Seed Savers Exchange.
Most modern tomato cultivars are smooth surfaced but some older tomato cultivars and most modern beefsteaks often show pronounced ribbing, a feature that may have been common to virtually all pre-Columbian cultivars. In addition, some tomato cultivars produce fruit in colors other than red, including yellow, orange, pink, black, brown, and purple, though such fruit is not widely available in grocery stores, nor are their seedlings available in typical nurseries, but must be bought as seed, often via mail-order. Likewise, some less common varieties have fuzzy skin on the fruit, as is the case with the Fuzzy Peach tomato and Red Boar tomato plants.
There is also a considerable gap between commercial and home-gardener cultivars; home cultivars are often bred for flavor to the exclusion of all other qualities, while commercial cultivars are bred for such factors as consistent size and shape, disease and pest resistance, and suitability for mechanized picking and shipping.
## Diseases and pests
Tomato cultivars vary widely in their resistance to disease. Modern hybrids focus on improving disease resistance over the heirloom plants. One common tomato disease is tobacco mosaic virus, and for this reason smoking or use of tobacco products are discouraged around tomatoes, although there is some scientific debate over whether the virus could possibly survive being burned and converted into smoke.[2] Various forms of mildew and blight are also common tomato afflictions, which is why tomato cultivars are often marked with a combination of letters which refer to specific disease resistance. The most common letters are: V - verticillium wilt, F - fusarium wilt strain I, FF - fusarium wilt strain I & II, N - nematodes, T - tobacco mosaic virus, and A - alternaria.
Another particularly dreaded disease is curly top, carried by the beet leafhopper, which interrupts the lifecycle, ruining a nightshade plant as a crop. As the name implies, it has the symptom of making the top leaves of the plant wrinkle up and grow abnormally.
Some common tomato pests are cutworms, tomato hornworms and tobacco hornworms, aphids, cabbage loopers, whiteflies, tomato fruitworms, flea beetles, red spider mite, slugs,[3] and Colorado potato beetles.
## Pollination
In the wild, original state, tomatoes required cross-pollination; they were much more self-incompatible than domestic cultivars. As a floral device to reduce selfing, the pistils of wild tomatoes extended farther out of the flower than today's cultivars. The stamens were, and remain, entirely within the closed corolla.
As tomatoes were moved from their native areas, their traditional pollinators, (probably a species of halictid bee) did not move with them. The trait of self-fertility (or self-pollenizing) became an advantage and domestic cultivars of tomato have been selected to maximize this trait.
This is not the same as self-pollination, despite the common claim that tomatoes do so. That tomatoes pollinate themselves poorly without outside aid is clearly shown in greenhouse situations where pollination must be aided by artificial wind, vibration of the plants (one brand of vibrator is a wand called an "electric bee" that is used manually), or more often today, by cultured bumblebees.
The anther of a tomato flower is shaped like a hollow tube, with the pollen produced within the structure rather than on the surface, as with most species. The pollen moves through pores in the anther, but very little pollen is shed without some kind of outside motion.
The best source of outside motion is a sonicating bee such as a bumblebee or the original wild halictid pollinator. In an outside setting, wind or biological agents provide sufficient motion to produce commercially viable crops.
## Hydroponic and greenhouse cultivation
Tomatoes are often grown in greenhouses in cooler climates, and indeed there are cultivars such as the British 'Moneymaker' and a number of cultivars grown in Siberia that are specifically bred for indoor growing. In more temperate climates, it is not uncommon to start seeds in greenhouses during the late winter for future transplant. With the transplanting of tomatoes, there is a process of hardening that the plant must go through before being able to be placed outside in order to have greater survival.[citation needed]
Hydroponic tomatoes are also available, and the technique is often used in hostile growing environments as well as high-density plantings.
## Picking and ripening
Tomatoes are often picked unripe (and thus green) and ripened in storage with ethylene. Ethylene is a hydrocarbon gas produced by many fruits that acts as the molecular cue to begin the ripening process. Tomatoes ripened in this way tend to keep longer but have poorer flavor and a mealier, starchier texture than tomatoes ripened on the plant. They may be recognized by their color, which is more pink or orange than the other ripe tomatoes' deep red.
In 1994 Calgene introduced a genetically modified tomato called the 'FlavrSavr' which could be vine ripened without compromising shelf life. However, the product was not commercially successful (see main article for details) and was only sold until 1997.
Recently, stores have begun selling "tomatoes on the vine", which are determinate varieties that are ripened or harvested with the fruits still connected to a piece of vine. These tend to have more flavor than artificially ripened tomatoes (at a price premium), but still may not be the equal of local garden produce.
Slow-ripening cultivars of tomato have been developed by crossing a non-ripening cultivar with ordinary tomato cultivars. Cultivars were selected whose fruits have a long shelf life and at least reasonable flavor.
## Modern uses of tomatoes
Tomatoes are now eaten freely throughout the world, and their consumption is believed to benefit the heart among other things. Lycopene, one of nature's most powerful antioxidants, is present in tomatoes, and, especially when tomatoes are cooked, has been found beneficial in preventing prostate cancer.[4] However, other research contradicts this claim. [5] Tomato extract branded as Lycomato is now also being promoted for treatment of high blood pressure. [6]
Though it is botanically a fruit, the tomato is nutritionally categorized as a vegetable (see below). Since "vegetable" is not a botanical term, there is no contradiction in a plant part being a fruit botanically while still being considered a vegetable.
Tomatoes are used extensively in Mediterranean and Middle Eastern cuisine, with Italian being the most notable. The tomato has an acidic property that is used to bring out other flavors. This same acidity makes tomatoes especially easy to preserve in home canning as tomato sauce or paste. The first to commercially can tomatoes was Harrison Woodhull Crosby in Jamesburg, New Jersey. Tomato juice is often canned and sold as a beverage. Unripe green tomatoes can also be used to make salsa, be breaded and fried, or pickled.
The town of Buñol, Spain, annually celebrates La Tomatina, a festival centered on an enormous tomato fight. Tomatoes are also a popular "non-lethal" throwing weapon in mass protests; and there is a common tradition of throwing rotten tomatoes at bad performers on a stage, although this tradition is more symbolic today. Embracing it for this protest connotation, the Dutch Socialist party adopted the tomato as their logo.
Known for its tomato growth and production, the Mexican state of Sinaloa takes the tomato as its symbol.[7]
Culinary uses of tomatoes include:
- Tomato paste
- Tomato purée
- Tomato pie
- Gazpacho (Andalusian cuisine)
- Ketchup
- Pa amb tomàquet (Catalan cuisine)
- Pizza
- Tomato sauce (common in Italian cuisine)
## Storage
Most tomatoes today are picked before fully ripe. They are bred to continue ripening, but the enzyme that ripens tomatoes stops working when it reaches temperatures below 12.5 °C (54.5 °F). Once an unripe tomato drops below that temperature, it will not continue to ripen. Once fully ripe, tomatoes can be stored in the refrigerator but are best kept and eaten at room temperature. Tomatoes stored in the refrigerator tend to lose flavor, but will still be edible;[8] thus the "Never Refrigerate" stickers sometimes placed on tomatoes in supermarkets.[9]
# Botanical Description
Tomato plants are vines, initially decumbent, typically growing six feet or more above the ground if supported, although erect bush varieties have been bred, generally three feet tall or shorter. It is a "tender" perennial, dying annually in temperate climates (to which it is not native). Tomato plants are dicots, and grow as a series of branching stems, with a terminal bud at the tip that does the actual growing. When that tip eventually stops growing, whether because of pruning or flowering, lateral buds take over and grow into other, fully functional, vines[2].
Tomato plant vines are typically pubescent, covered with tiny hairs. These hairs facilitate the vining process, turning into roots wherever the plant is in contact with the ground and moisture, especially if there is some issue with the vine's contact to its original root.
Tomato plants generally have compound leaves, known as Regular Leaf (RL) plants. Some cultivars, though, have simple leaves known as potato leaf style because of their resemblance to that close cousin. Of regular leaf varieties, there are variations, such as rugose leaves, which are deeply grooved, angora leaves, which are pubescent (hairy), and variegated, which have additional colors where a genetic flaw excludes chlorophyll from the leaves[3].
Their flowers, appearing on the apical meristem, have the anthers fused along the edges, forming a column surrounded by the pistil's style. These tend to be self-fertilizing. This is because they are native to the Americas; all plants from the New World evolved without honeybees (which are native to the old world, only), and have other specific means of fertilization[4].
Its fruit is classified, botanically, as a berry. As a true fruit, it develops from the ovary of the plant after fertilization, its flesh comprising the pericarp walls. The fruit contains hollow spaces full of seeds and moisture, called locular cavities. These vary, among cultivated species, according to type. Some smaller tomatoes have two cavities, globe-shaped typically have three to five, and beefsteak having a great number of smaller ones, while paste tomatoes have very few, very small cavities.
The seeds need to come from a mature fruit, and be dried/fermented before germination.
# Myths of the tomato
Template:Nofootnotes
There are many legends about the tomato. For example, it has been claimed that tomatoes were not widely eaten in the U.S. until the late 1800s. It has sometimes been claimed that tomatoes were considered aphrodisiacs and so were shunned by the Puritans. Other claims center on the supposed fear that tomatoes were poisonous, based on the fact that they belong to the Solanales Order, or "Nightshade" family, which contains many toxic plants. Many legends also maintain that the tomato was introduced into the U.S. from South America by one particular person; Thomas Jefferson is sometimes mentioned.
Tomatoes' status as an aphrodisiac may be due to a mistranslation. Legend has it a Frenchman on his travels ate a meal with tomatoes in it and was fascinated with the new taste. He went back to the chef, who was Italian, and asked him what this new ingredient was. The chef said "Pomme de Maure" (Apple of the Moors), but the Frenchman misunderstood and thought he said "Pomme d'amour" (apple of love). The modern Italian word for tomato is "pomodoro."
In the United States, the most famous legend of this sort was introduced by Joseph S. Sickler in the mid-1900s, and became the subject of a CBS broadcast of You Are There in 1949. The story goes that the lingering doubts about the safety of the tomato in the United States were largely put to rest in 1820, when Colonel Robert Gibbon Johnson announced that at noon on September 26, he would eat a basket of tomatoes in front of the Salem, New Jersey courthouse. Reportedly, a crowd of more than 2,000 persons gathered in front of the courthouse to watch the poor man die after eating the poisonous fruits, and were shocked when he lived. In his book Smith notes that there is little, if any, historical evidence for any of these legends, and that they continue to be repeated largely because they are entertaining stories.
It is also said that the tomato became popular in France during the French Revolution, because the revolutionaries' iconic color was red; and at one point it was suggested that they should eat red food as a show of loyalty. Since European royalty was still leery of the nightshade-related tomato, it apparently was the perfect choice. This may also be why the first reported use of the tomato in the U.S. was in New Orleans, Louisiana in 1812, because of the French influence in that region.
There is also a story which claims that an agent for Britain attempted to kill General George Washington by feeding him a dish laced with tomatoes during the American Revolution.
"Tomato" also has been used as a slang word for an attractive woman. This use was most common from the 1920s through the 1940s and only within the USA.
# Controversies
## Botanical classification
In 1753 the tomato was placed in the genus Solanum by Linnaeus as Solanum lycopersicum L. (derivation, 'lyco', wolf, plus 'persicum', peach, i.e., "wolf-peach"). However, in 1768 Philip Miller placed it in its own genus, and he named it Lycopersicon esculentum. This name came into wide use but was in breach of the plant naming rules. Technically, the combination Lycopersicon lycopersicum (L.) H.Karst. would be more correct, but this name (published in 1881) has hardly ever been used. Therefore, it was decided to conserve the well-known Lycopersicon esculentum, making this the correct name for the tomato when it is placed in the genus Lycopersicon.
However, genetic evidence (e.g., Peralta & Spooner 2001) has now shown that Linnaeus was correct in the placement of the tomato in the genus Solanum, making the Linnaean name correct; if Lycopersicon is excluded from Solanum, Solanum is left as a paraphyletic taxon. Despite this, it is likely that the exact taxonomic placement of the tomato will be controversial for some time to come, with both names found in the literature.
The Boyce Thompson Institute for Plant Research began sequencing the tomato genome in 2004 and is creating a database of genomic sequences and information on the tomato and related plants.[10] A draft version of the full genome expected to be published by 2008. The genomes of its organelles (mitochondria and chloroplast) are also expected to be published as part of the project.
## Fruit or vegetable?
Botanically, a tomato is the ovary, together with its seeds, of a flowering plant: a fruit or, more precisely, a berry. However, the tomato is not as sweet as those foodstuffs usually called fruits and, from a culinary standpoint, it is typically served as part of a salad or main course of a meal, as are vegetables, rather than at dessert, as are fruits. As noted above, the term "vegetable" has no botanical meaning and is purely a culinary term.
This argument has had legal implications in the United States. In 1887, U.S. tariff laws that imposed a duty on vegetables but not on fruits caused the tomato's status to become a matter of legal importance. The U.S. Supreme Court settled the controversy in 1893 by declaring that the tomato is a vegetable, based on the popular definition that classifies vegetables by use, that they are generally served with dinner and not dessert (Nix v. Hedden (149 U.S. 304)). The holding of the case applies only to the interpretation of the Tariff Act of March 3, 1883, and the court did not purport to reclassify the tomato for botanical or other purposes other than paying a tax under a tariff act.
The tomato has been designated the state vegetable of New Jersey. Arkansas took both sides by declaring the "South Arkansas Vine Ripe Pink Tomato" to be both the state fruit and the state vegetable in the same law, citing both its botanical and culinary classifications. In 2006, the Ohio House of Representatives passed a law that would have declared the tomato to be the official state fruit, but the bill died when the Ohio Senate failed to act on it. Tomato juice has been the official beverage of Ohio since 1965. A.W. Livingston, of Reynoldsburg, Ohio played a large part in popularizing the tomato in the late 1800's.
But due to the scientific definition of a fruit, the tomato remains a fruit when not dealing with US tariffs. Nor is it the only culinary vegetable that is a botanical fruit: eggplants, cucumbers, and squashes of all kinds (such as zucchini and pumpkins) share the same ambiguity.
## Pronunciation
The pronunciation of tomato differs in different English-speaking countries; the two most common variants are Template:IPA and Template:IPA. Speakers from the British Isles, most of the Commonwealth, and older generations among speakers of Southern American English typically say Template:IPA, while most American and Canadian speakers usually say Template:IPA. Most or all languages, apart from American English, have a word that corresponds more to the former pronunciation, including the original Nahuatl word from which they are all taken.
The word's dual pronunciations were immortalized in Ira and George Gershwin's 1937 song "Let's Call the Whole Thing Off" (You like Template:IPA and I like Template:IPA / You like Template:IPA and I like Template:IPA) and have become a symbol for nitpicking pronunciation disputes. In this capacity it has even become an American slang term: saying Template:IPA when presented with two choices can mean "What's the difference?" or "It's all the same to me."
## Safety
On October 30, 2006 the U.S. Centers for Disease Control and Prevention (CDC) announced that tomatoes might be the source of a salmonella outbreak causing 172 illnesses in 18 states [5]. The affected states include Arkansas, Connecticut, Georgia, Indiana, Kentucky, Maine, Massachusetts, Michigan, Minnesota, North Carolina, New Hampshire, Ohio, Pennsylvania, Rhode Island, Tennessee, Virginia, Vermont and Wisconsin. Tomatoes have been linked to seven salmonella outbreaks since 1990 (from the Food Safety Network).[11]
# Tomato records
The heaviest tomato ever was one of 3.51 kg (7 lb 12 oz), of the cultivar 'Delicious', grown by Gordon Graham of Edmond, Oklahoma in 1986.[citation needed] The largest tomato plant grown was of the cultivar 'Sungold' and reached 19.8 m (65 ft) length, grown by Nutriculture Ltd (UK) of Mawdesley, Lancashire, UK, in 2000.[citation needed]
The massive "tomato tree" growing inside the Walt Disney World Resort's experimental greenhouses in Lake Buena Vista, Florida may be the largest single tomato plant in the world. The plant has been recognized as a Guinness World Record Holder, with a harvest of more than 32,000 tomatoes and a total weight of 1,151.84 pounds. This one-of-a-kind plant yields thousands of tomatoes at one time from a single vine. Yong Huang, Epcot's manager of agricultural science discovered the unique plant in Beijing, China. Huang brought its seeds to Epcot and created the specialized greenhouse for the fruit to grow. The vine grows golf ball-sized tomatoes which are served at Walt Disney World restaurants. The world record-setting tomato tree can be seen by guests along the Living With the Land boat ride at Epcot.
Tomatina Festival
On August 30, 2007, 40,000 Spaniards gathered in Buñol to throw 115,000 kilograms of tomatoes at each other in the yearly Tomatina festival. Bare-chested tourists also included hundreds of British, French and Germans.[12] | https://www.wikidoc.org/index.php/Tomato | |
30b1eef81d6dae550d249f26367ed439ffb15fd2 | wikidoc | Tongue | Tongue
# Overview
The tongue is the large bundle of skeletal muscles on the floor of the mouth that manipulates food for chewing and swallowing (deglutition). It is the primary organ of taste. Much of the surface of the tongue is covered in taste buds. The tongue, with its wide variety of possible movements, assists in forming the sounds of speech. It is sensitive and kept moist by saliva, and is richly supplied with nerves and blood vessels to help it move.
The tongue is often cited as the "strongest muscle in the body," a claim that does not correspond to any conventional definition of strength. For more on this subject, see Muscle: The strongest human muscle.
# "Tongue" as a word
The word tongue can be used as a metonym for language, as in the phrase mother tongue. In fact, Albanian (gjuha), Catalan (llengua), Portuguese (língua), French (langue), Maltese, (ilsien), Arabic (لسان lisān), Romanian (limba), Russian (язык yazyk), Bulgarian (ezik), Persian (zabaan), Greek (γλώσσα), Spanish (lengua), Polish, Slovak, Czech, Slovene, Bosnian, Serbian, Croatian ( jezik), Armenian (լեզու), Finnish (kieli), Estonian (keel), Irish, Icelandic (tunga), Italian (lingua), Latin (lingua), Urdu (za'baan), Aramaic (ܠܫܢܐ/לשנא lišānā), Hungarian (nyelv), Hebrew (לָשׁוֹן lashon), and Turkish (dil), have the same word for "tongue" and "language". A common temporary failure in word retrieval from memory is referred to as the tip-of-the-tongue phenomenon. The term "tongue in cheek" also exists. "Tongue twisted" is a term used to described being unable to pronounce a word or phrase correctly. A "tongue twister" is a phrase made specifically to be very difficult to pronounce.
An example of a tongue twister is: She sells seashells by the seashore. Another example is: Peter Piter picked a peck of pickled peppers. If Peter Piter picked a peck of pickled peppers, how many pickled peppers did Peter Piter pick? Tongue Twisters are meant to trick your tongue.
# Anatomy
## Structure
The tongue is made mainly of skeletal muscle. The tongue extends much further than is commonly perceived, past the posterior border of the mouth and into the oropharynx.
The dorsum (upper surface) of the tongue can be divided into two parts:
- an oral part (anterior two-thirds of the tongue) that lies mostly in the mouth
- a pharyngeal part (posterior third of the tongue), which faces backward to the oropharynx
The two parts are separated by a V-shaped groove, which marks the sulcus terminalis (or terminal sulcus).
Since the tongue contains no bony supports for the muscles, the tongue is an example of a muscular hydrostat, similar in concept to an octopus arm. Instead of bony attachments, the extrinsic muscles of the tongue anchor the tongue firmly to surrounding bones and prevent the mythical possibility of 'swallowing' the tongue.
Other divisions of the tongue, are based on the area of the tongue:
## Muscles of the tongue
The intrinsic muscles lie entirely within the tongue, while the extrinsic muscles attach the tongue to other structures.
The extrinsic muscles reposition the tongue, while the intrinsic muscles alter the shape of the tongue for talking and swallowing.
### Extrinsic muscles
Extrinsic muscles of the tongue by definition originate from structures outside the tongue and insert into the tongue. The four paired extrinsic muscles protrude, retract, depress, and elevate the tongue:
### Intrinsic muscles
Four paired intrinsic muscles of the tongue originate and insert within the tongue, running along its length. These muscles alter the shape of the tongue by: lengthening and shortening it, curling and uncurling its apex and edges, and flattening and rounding its surface.
- The superior longitudinal muscle runs along the superior surface of the tongue under the mucous membrane, and elevates, assists in retraction of, or deviates the tip of the tongue. It originates near the epiglottis, the hyoid bone, from the median fibrous septum.
- The inferior longitudinal muscle lines the sides of the tongue, and is joined to the styloglossus muscle.
- The verticalis muscle is located in the middle of the tongue, and joins the superior and inferior longitudinal muscles.
- The transversus muscle divides the tongue at the middle, and is attached to the mucous membranes that run along the sides.
## Papillae and taste buds
The oral part of the tongue is covered with small bumpy projections called papillae. There are four types of papillae:
- filiform (thread-shape)
- fungiform (mushroom-shape)
- circumvallate (ringed-circle)
- foliate
All papillae except the filiform have taste buds on their surface.
The circumvallate are the largest of the papillae. There are 8 to 14 circumvallate papillae arranged in a V-shape in front of the sulcus terminalis, creating a border between the oral and pharyngeal parts of the tongue.
There are no lingual papillae on the underside of the tongue. It is covered with a smooth mucous membrane, with a fold (the lingual frenulum) in the center. If the lingual frenulum is too taut or too far forward, it can impede motion of the tongue, a condition called Tongue-tie (Ankyloglossia).
The upper side of the posterior tongue (pharyngeal part) has no visible taste buds, but it is bumpy because of the lymphatic nodules lying underneath. These follicles are known as the lingual tonsil.
The human tongue can detect five basic taste components: sweet, sour, salty, bitter and umami. The sense of taste is referred to as a gustatory sense. Contrary to the popular myth and generations of schoolbooks, there are no distinct regions for tasting different tastes. This myth arose because Edwin_G._Boring replotted data from one of Wundt's students (Hanig) without labeling the axes, leading some to misinterpret the graph as all or nothing response. The common conception of taste has a significant contribution from olfaction.
## Innervation of the tongue
Motor innervation of the tongue is complex and involves several cranial nerves. All the muscles of the tongue are innervated by the hypoglossal nerve (cranial nerve XII) with one exception: the palatoglossal muscle is innervated by the pharyngeal branch of vagus nerve (cranial nerve X).
Sensory innervation of the tongue is different for taste sensation and general sensation.
- In the pharyngeal part of the tongue (posterior third), taste and general sensations are carried by the glossopharyngeal nerve (cranial nerve IX).
- Somatic sensations from the oral part of the tongue (anterior two-thirds) (as well as areas of the oral mucosa and gingiva of the lower teeth) travel from the tongue via the lingual nerve, a major branch of the mandibular nerve (itself a branch of the trigeminal nerve, cranial nerve V). Taste sensation of the anterior two-thirds of the tongue is carried to the facial nerve via the chorda tympani. The chorda tympani also carries parasmpathetic fibers from the facial nerve to the submandibular ganglion.
## Vasculature of the tongue
The tongue receives its blood supply primarily from the lingual artery, a branch of the external carotid artery. The floor of the mouth also receives its blood supply from the lingual artery.
There is also secondary blood supply to the tongue from the tonsillar branch of the facial artery and the ascending pharyngeal artery.
# Use of tongue in pharmacy
The sublingual region underneath the front of the tongue is a location where the oral mucosa is very thin, and underlied by a plexus of veins. This is an ideal location for introducing certain medications to the body. The sublingual route takes advantage of the highly vascular quality of the oral cavity, and allows for the speedy application of medication into the cardiovascular system, bypassing the gastrointestinal tract. This is the only convenient and efficacious route of administration of nitroglycerin to a patient suffering angina pectoris, chest pain. If the tablet is swallowed, the medication is completely neutralized by the detoxification process of the liver.
# Clinical significance
White tongue: White spots and patches or coating of the tongue are a symptom of several medical conditions:
- Antibiotics side effect
- Oral candidiasis
- Dehydration
- Leukoplakia
- Keratosis pharyngis
- Jaundice - causes a yellow tongue
- "Lie Bumps" - small dots usually on tip of tongue
The tongue is also examined and observed diagnostically in traditional Chinese medicine. A painful tongue may be an indication of several underlying serious medical conditions
# Secondary uses
In addition to eating and human vocalization, the human tongue has many secondary uses. These include certain forms of kissing known as "tongue kissing" or sometimes "french kissing" in which the tongue plays a primary role. Generally, use of the tongue (such as licking), or interaction between tongues, appears to be a common gesture of affection, not just in humans but throughout the animal kingdom, and particularly in mammals.
The tongue also has a distinct use in both male and female forms of oral sex, and is typically used to a great extent in foreplay and traditional sexual intercourse as well. Because of its use in both the phenomenon of human sexual interactions, the tongue sometimes is associated with a sensual or erotic connotation. In art the human tongue is often depicted as a seductive instrument, similar to the status of the lips.
The tongue is also one of the more common parts of the human anatomy to be subject to piercing and body modification, a phenomenon that is sometimes associated with certain subcultures or demographics. Tongue piercing has appeared historically in many ancient cultures, and is an increasingly popular trend in the West today, particularly in youth culture. Pop culture references to tongue piercings are common as well.
Showing tongue (tongue out) is an international emotional gesture used primarily by children, or by adults behaving (deliberately or not) in a childish manner.
The human tongue also plays a valuable role in other acts, such as for blowing bubbles with bubble gum and whistling.
Injury to the tongue is often very painful. The muscle is vulnerable to various cancers.
# Non-human tongues
Most multi-cellular animals, that is, members of the subkingdom Metazoa, have tongues or similar organs.
In animals, such as dogs and cats, the tongue is often used to clean the fur and body. Rough textures of the tongues of these species helps them to use their tongues to remove oils and parasites by licking themselves and each other. Aside from daily uses for eating and drinking, a dog's tongue acts as a heat regulator. As a dog increases its exercise the tongue will increase in size due to greater blood flow. The tongue hangs out of the dog's mouth and the moisture on the tongue will cool down further cooling down the bloodflow.
Some animals have prehensile tongues. For example, chameleons, frogs, salamanders and some species of fish use their tongues to catch prey. Many insects have a type of tongue called a proboscis that is used for the same purpose or, in the case of butterflies, to drink nectar . The corresponding organ in ants is called the hypopharynx . Molluscs have a rough tongue called a radula , which they use to grind food.
# Tongue rolling
Tongue rolling is the act of rolling the tongue axially into a tube shape. The ability to roll the tongue has been generally believed to depend on genetic inheritance. Tongue rolling was believed to be a dominant trait with simple Mendelian inheritance, and is still commonly used as an example in high school and introductory biology courses. It provided a simple experiment to demonstrate inheritance.
There is little laboratory evidence, though, for the common belief that tongue rolling is inheritable and dominant. A 1975 twin study found that identical twins (who share all of their genes) were no more likely than fraternal twins (who share an average of half) to both have the same phenotype for tongue rolling.
# Tongue as a food
The tongues of some animals are consumed and sometimes considered delicacies. In America and the United Kingdom, cow tongues are among the more common. Hot tongue sandwiches are frequently found on menus in Kosher delicatessens and in America. In the United Kingdom tongue can often be found at the local grocer, where it is often sold in reformed slices of meat after being ground up and set in gelatine. Taco de lengua (lengua being Spanish for tongue) is a taco filled with beef tongue, and is especially popular in Mexican cuisine. Tongue can also be prepared as birria. Duck tongues are sometimes employed in Szechuan dishes, while lamb's tongue is occasionally employed in Continental and contemporary American cooking. Fried cod tongue is a relatively common part of fish meals in Norway and Newfoundland.
Tongues are also used in sausage making. Historically, buffalo tongue was once considered an especially exquisite dish, and is one of the reasons for the American Bison being hunted by humans to the point of near extinction.
# Miscellaneous facts
- Tung was the original Webster spelling of tongue
- Stephen Taylor holds the world record for the world's longest tongue. It measures 9.5 centimeters from the tip to the center of his closed top lip. Annika Irmler holds the record for longest female tongue, at 7 centimeters.
# Additional images
- The entrance to the larynx, viewed from behind.
- Sagittal section of nose mouth, pharynx, and larynx. | Tongue
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
# Overview
Template:Infobox Anatomy
The tongue is the large bundle of skeletal muscles on the floor of the mouth that manipulates food for chewing and swallowing (deglutition). It is the primary organ of taste. Much of the surface of the tongue is covered in taste buds. The tongue, with its wide variety of possible movements, assists in forming the sounds of speech. It is sensitive and kept moist by saliva, and is richly supplied with nerves and blood vessels to help it move.
The tongue is often cited as the "strongest muscle in the body," a claim that does not correspond to any conventional definition of strength. For more on this subject, see Muscle: The strongest human muscle.
# "Tongue" as a word
The word tongue can be used as a metonym for language, as in the phrase mother tongue. In fact, Albanian (gjuha), Catalan (llengua), Portuguese (língua), French (langue), Maltese, (ilsien), Arabic (لسان lisān), Romanian (limba), Russian (язык yazyk), Bulgarian (ezik), Persian (zabaan), Greek (γλώσσα), Spanish (lengua), Polish, Slovak, Czech, Slovene, Bosnian, Serbian, Croatian ( jezik), Armenian (լեզու), Finnish (kieli), Estonian (keel), Irish, Icelandic (tunga), Italian (lingua), Latin (lingua), Urdu (za'baan), Aramaic (ܠܫܢܐ/לשנא lišānā), Hungarian (nyelv), Hebrew (לָשׁוֹן lashon), and Turkish (dil), have the same word for "tongue" and "language". A common temporary failure in word retrieval from memory is referred to as the tip-of-the-tongue phenomenon. The term "tongue in cheek" also exists. "Tongue twisted" is a term used to described being unable to pronounce a word or phrase correctly. A "tongue twister" is a phrase made specifically to be very difficult to pronounce.
An example of a tongue twister is: She sells seashells by the seashore. Another example is: Peter Piter picked a peck of pickled peppers. If Peter Piter picked a peck of pickled peppers, how many pickled peppers did Peter Piter pick? Tongue Twisters are meant to trick your tongue.
# Anatomy
## Structure
The tongue is made mainly of skeletal muscle. The tongue extends much further than is commonly perceived, past the posterior border of the mouth and into the oropharynx.
The dorsum (upper surface) of the tongue can be divided into two parts:
- an oral part (anterior two-thirds of the tongue) that lies mostly in the mouth
- a pharyngeal part (posterior third of the tongue), which faces backward to the oropharynx
The two parts are separated by a V-shaped groove, which marks the sulcus terminalis (or terminal sulcus).
Since the tongue contains no bony supports for the muscles, the tongue is an example of a muscular hydrostat, similar in concept to an octopus arm. Instead of bony attachments, the extrinsic muscles of the tongue anchor the tongue firmly to surrounding bones and prevent the mythical possibility of 'swallowing' the tongue.
Other divisions of the tongue, are based on the area of the tongue:
## Muscles of the tongue
The intrinsic muscles lie entirely within the tongue, while the extrinsic muscles attach the tongue to other structures.
The extrinsic muscles reposition the tongue, while the intrinsic muscles alter the shape of the tongue for talking and swallowing.
### Extrinsic muscles
Extrinsic muscles of the tongue by definition originate from structures outside the tongue and insert into the tongue. The four paired extrinsic muscles protrude, retract, depress, and elevate the tongue:
### Intrinsic muscles
Four paired intrinsic muscles of the tongue originate and insert within the tongue, running along its length. These muscles alter the shape of the tongue by: lengthening and shortening it, curling and uncurling its apex and edges, and flattening and rounding its surface.[1]
- The superior longitudinal muscle runs along the superior surface of the tongue under the mucous membrane, and elevates, assists in retraction of, or deviates the tip of the tongue. It originates near the epiglottis, the hyoid bone, from the median fibrous septum.
- The inferior longitudinal muscle lines the sides of the tongue, and is joined to the styloglossus muscle.
- The verticalis muscle is located in the middle of the tongue, and joins the superior and inferior longitudinal muscles.
- The transversus muscle divides the tongue at the middle, and is attached to the mucous membranes that run along the sides.
## Papillae and taste buds
The oral part of the tongue is covered with small bumpy projections called papillae. There are four types of papillae:
- filiform (thread-shape)
- fungiform (mushroom-shape)
- circumvallate (ringed-circle)
- foliate
All papillae except the filiform have taste buds on their surface.
The circumvallate are the largest of the papillae. There are 8 to 14 circumvallate papillae arranged in a V-shape in front of the sulcus terminalis, creating a border between the oral and pharyngeal parts of the tongue.
There are no lingual papillae on the underside of the tongue. It is covered with a smooth mucous membrane, with a fold (the lingual frenulum) in the center. If the lingual frenulum is too taut or too far forward, it can impede motion of the tongue, a condition called Tongue-tie (Ankyloglossia).
The upper side of the posterior tongue (pharyngeal part) has no visible taste buds, but it is bumpy because of the lymphatic nodules lying underneath. These follicles are known as the lingual tonsil.
The human tongue can detect five basic taste components: sweet, sour, salty, bitter and umami. The sense of taste is referred to as a gustatory sense. Contrary to the popular myth and generations of schoolbooks, there are no distinct regions for tasting different tastes. This myth arose because Edwin_G._Boring replotted data from one of Wundt's students (Hanig) without labeling the axes, leading some to misinterpret the graph as all or nothing response. [2] The common conception of taste has a significant contribution from olfaction.
## Innervation of the tongue
Motor innervation of the tongue is complex and involves several cranial nerves. All the muscles of the tongue are innervated by the hypoglossal nerve (cranial nerve XII) with one exception: the palatoglossal muscle is innervated by the pharyngeal branch of vagus nerve (cranial nerve X).
Sensory innervation of the tongue is different for taste sensation and general sensation.
- In the pharyngeal part of the tongue (posterior third), taste and general sensations are carried by the glossopharyngeal nerve (cranial nerve IX).
- Somatic sensations from the oral part of the tongue (anterior two-thirds) (as well as areas of the oral mucosa and gingiva of the lower teeth) travel from the tongue via the lingual nerve, a major branch of the mandibular nerve (itself a branch of the trigeminal nerve, cranial nerve V). Taste sensation of the anterior two-thirds of the tongue is carried to the facial nerve via the chorda tympani. The chorda tympani also carries parasmpathetic fibers from the facial nerve to the submandibular ganglion.
## Vasculature of the tongue
The tongue receives its blood supply primarily from the lingual artery, a branch of the external carotid artery. The floor of the mouth also receives its blood supply from the lingual artery.
There is also secondary blood supply to the tongue from the tonsillar branch of the facial artery and the ascending pharyngeal artery.
# Use of tongue in pharmacy
The sublingual region underneath the front of the tongue is a location where the oral mucosa is very thin, and underlied by a plexus of veins. This is an ideal location for introducing certain medications to the body. The sublingual route takes advantage of the highly vascular quality of the oral cavity, and allows for the speedy application of medication into the cardiovascular system, bypassing the gastrointestinal tract. This is the only convenient and efficacious route of administration of nitroglycerin to a patient suffering angina pectoris, chest pain. If the tablet is swallowed, the medication is completely neutralized by the detoxification process of the liver.
# Clinical significance
White tongue: White spots and patches or coating of the tongue are a symptom of several medical conditions:
- Antibiotics side effect
- Oral candidiasis
- Dehydration
- Leukoplakia
- Keratosis pharyngis
- Jaundice - causes a yellow tongue
- "Lie Bumps" - small dots usually on tip of tongue
The tongue is also examined and observed diagnostically in traditional Chinese medicine. A painful tongue may be an indication of several underlying serious medical conditions [3]
# Secondary uses
In addition to eating and human vocalization, the human tongue has many secondary uses. These include certain forms of kissing known as "tongue kissing" or sometimes "french kissing" in which the tongue plays a primary role. Generally, use of the tongue (such as licking), or interaction between tongues, appears to be a common gesture of affection, not just in humans but throughout the animal kingdom, and particularly in mammals.
The tongue also has a distinct use in both male and female forms of oral sex, and is typically used to a great extent in foreplay and traditional sexual intercourse as well. Because of its use in both the phenomenon of human sexual interactions, the tongue sometimes is associated with a sensual or erotic connotation. In art the human tongue is often depicted as a seductive instrument, similar to the status of the lips.
The tongue is also one of the more common parts of the human anatomy to be subject to piercing and body modification, a phenomenon that is sometimes associated with certain subcultures or demographics. Tongue piercing has appeared historically in many ancient cultures, and is an increasingly popular trend in the West today, particularly in youth culture. Pop culture references to tongue piercings are common as well.
Showing tongue (tongue out) is an international emotional gesture used primarily by children, or by adults behaving (deliberately or not) in a childish manner.
The human tongue also plays a valuable role in other acts, such as for blowing bubbles with bubble gum and whistling.
Injury to the tongue is often very painful. The muscle is vulnerable to various cancers.
# Non-human tongues
Most multi-cellular animals, that is, members of the subkingdom Metazoa, have tongues or similar organs.
In animals, such as dogs and cats, the tongue is often used to clean the fur and body. Rough textures of the tongues of these species helps them to use their tongues to remove oils and parasites by licking themselves and each other. Aside from daily uses for eating and drinking, a dog's tongue acts as a heat regulator. As a dog increases its exercise the tongue will increase in size due to greater blood flow. The tongue hangs out of the dog's mouth and the moisture on the tongue will cool down further cooling down the bloodflow.[2][3]
Some animals have prehensile tongues. For example, chameleons, frogs, salamanders and some species of fish use their tongues to catch prey. Many insects have a type of tongue called a proboscis that is used for the same purpose or, in the case of butterflies, to drink nectar [4]. The corresponding organ in ants is called the hypopharynx [5]. Molluscs have a rough tongue called a radula [6], which they use to grind food.
# Tongue rolling
Tongue rolling is the act of rolling the tongue axially into a tube shape. The ability to roll the tongue has been generally believed to depend on genetic inheritance. Tongue rolling was believed to be a dominant trait with simple Mendelian inheritance, and is still commonly used as an example in high school and introductory biology courses. It provided a simple experiment to demonstrate inheritance.
There is little laboratory evidence, though, for the common belief that tongue rolling is inheritable and dominant. A 1975 twin study found that identical twins (who share all of their genes) were no more likely than fraternal twins (who share an average of half) to both have the same phenotype for tongue rolling.[4][5]
# Tongue as a food
The tongues of some animals are consumed and sometimes considered delicacies. In America and the United Kingdom, cow tongues are among the more common. Hot tongue sandwiches are frequently found on menus in Kosher delicatessens and in America. In the United Kingdom tongue can often be found at the local grocer, where it is often sold in reformed slices of meat after being ground up and set in gelatine. Taco de lengua (lengua being Spanish for tongue) is a taco filled with beef tongue, and is especially popular in Mexican cuisine. Tongue can also be prepared as birria. Duck tongues are sometimes employed in Szechuan dishes, while lamb's tongue is occasionally employed in Continental and contemporary American cooking. Fried cod tongue is a relatively common part of fish meals in Norway and Newfoundland.
Tongues are also used in sausage making. Historically, buffalo tongue was once considered an especially exquisite dish, and is one of the reasons for the American Bison being hunted by humans to the point of near extinction.
# Miscellaneous facts
- Tung was the original Webster spelling of tongue
- Stephen Taylor holds the world record for the world's longest tongue. It measures 9.5 centimeters from the tip to the center of his closed top lip. Annika Irmler holds the record for longest female tongue, at 7 centimeters.[6]
# Additional images
- The entrance to the larynx, viewed from behind.
- Sagittal section of nose mouth, pharynx, and larynx. | https://www.wikidoc.org/index.php/Tongue | |
03f058598f1af186abd50d528f8c0d142d76c576 | wikidoc | Tonsil | Tonsil
# Overview
The tongue is a muscular hydrostat on the floor of the mouth of most vertebrates that manipulates food for mastication. It is the primary organ of taste (gustation), as much of its upper surface is covered in taste buds. The tongue's upper surface is also covered in numerous lingual papillae. It is sensitive and kept moist by saliva, and is richly supplied with nerves and blood vessels. In humans a secondary function of the tongue is phonetic articulation. The tongue also serves as a natural means of cleaning the teeth. The ability to perceive different tastes is not localised in different parts of the tongue, as is widely believed. This error arose because of misinterpretation of some 19th-century research (see tongue map).
# Structure
The tongue is a muscular structure that forms part of the floor of the oral cavity. The left and right sides of the tongue are separated by the lingual septum. The human tongue is divided into anterior and posterior parts. The anterior part is the visible part situated at the front and makes up roughly two-thirds the length of the tongue. The posterior part is the part closest to the throat, roughly one-third of its length. These parts differ in terms of their embryological development and nerve supply. The two parts of the tongue are divided by the terminal sulcus.:989–990
The anterior tongue is, at its apex, thin and narrow, it is directed forward against the lingual surfaces of the lower incisor teeth. The posterior part is, at its root, directed backward, and connected with the hyoid bone by the hyoglossi and genioglossi muscles and the hyoglossal membrane, with the epiglottis by three folds (glossoepiglottic) of mucous membrane, with the soft palate by the glossopalatine arches, and with the pharynx by the superior pharyngeal constrictor muscle and the mucous membrane. It also forms the anterior wall of the oropharynx.
In phonetics and phonology, a distinction is made between the tip of the tongue and the blade (the portion just behind the tip). Sounds made with the tongue tip are said to be apical, while those made with the tongue blade are said to be laminal.
## Muscles
The eight muscles of the human tongue are classified as either intrinsic or extrinsic. The four intrinsic muscles act to change the shape of the tongue, and are not attached to any bone. The four extrinsic muscles act to change the position of the tongue, and are anchored to bone.
- Coronal section of tongue, showing intrinsic muscles
- Lateral view of the tongue, with extrinsic muscles highlighted.
### Extrinsic
The extrinsic muscles originate from bone and extend to the tongue. Their main functions are altering the tongue's position allowing for protrusion, retraction, and side-to-side movement.:991
- Genioglossus, which arises from the mandible and protrudes the tongue. It is also known as the "safety muscle" of the tongue since it is the only muscle having the forward action.
- Hyoglossus, which arises from the hyoid bone and depresses the tongue
- Styloglossus, which arises from the styloid process of the temporal bone and elevates and retracts the tongue
- Palatoglossus, which arises from the palatine aponeurosis, and depresses the soft palate, moves the palatoglossal fold towards the midline, and elevates the back of the tongue.
### Intrinsic
Four paired intrinsic muscles of the tongue originate and insert within the tongue, running along its length. These muscles alter the shape of the tongue by: lengthening and shortening it, curling and uncurling its apex and edges, and flattening and rounding its surface. This provides shape, and helps facilitate speech, swallowing, and eating.:991
- The superior longitudinal muscle runs along the superior surface of the tongue under the mucous membrane, and elevates, assists in retraction of, or deviates the tip of the tongue. It originates near the epiglottis, the hyoid bone, from the median fibrous septum.
- The inferior longitudinal muscle lines the sides of the tongue, and is joined to the styloglossus muscle.
- The vertical muscle is located in the middle of the tongue, and joins the superior and inferior longitudinal muscles.
- The transverse muscle divides the tongue at the middle, and is attached to the mucous membranes that run along the sides.
## Blood supply
The tongue receives its blood supply primarily from the lingual artery, a branch of the external carotid artery. The lingual veins, drain into the internal jugular vein. The floor of the mouth also receives its blood supply from the lingual artery.:993–994 There is also a secondary blood supply to the tongue from the tonsillar branch of the facial artery and the ascending pharyngeal artery.
An area in the neck sometimes called Pirogov's triangle is formed by the intermediate tendon of the digastric muscle, the posterior border of the mylohyoid muscle, and the hypoglossal nerve. The lingual artery is a good place to stop severe hemorrage from the tongue.
## Innervation
Innervation of the tongue consists of motor fibers, special sensory fibers for taste, and general sensory fibers for sensation.:994–5
- Motor supply for all intrinsic and extrinsic muscles of the tongue is supplied by efferent motor nerve fibers from the hypoglossal nerve (CN XII), with the exception of the palatoglossus. The palatoglossus is innervated by the vagus nerve (CN X).:995
Innervation of taste and sensation is different for the anterior and posterior part of the tongue because they are derived from different embryological structures (pharyngeal arch 1 and pharyngeal arch 3 and 4, respectively).
- Anterior two thirds of tongue (anterior to the vallate papillae):
Taste: chorda tympani branch of the facial nerve (CN VII) via special visceral afferent fibers
Sensation: lingual branch of the mandibular division (V3) of the trigeminal nerve (CN V) via general somatic afferent fibers
- Taste: chorda tympani branch of the facial nerve (CN VII) via special visceral afferent fibers
- Sensation: lingual branch of the mandibular division (V3) of the trigeminal nerve (CN V) via general somatic afferent fibers
- Posterior one third of tongue:
Taste and sensation: glossopharyngeal nerve (CN IX) via a mixture of special and general visceral afferent fibers
- Taste and sensation: glossopharyngeal nerve (CN IX) via a mixture of special and general visceral afferent fibers
## Histology
The tongue is covered with numerous taste buds, and filiform, fungiform, vallate and foliate, lingual papillae.:990
## Length
The average length of the human tongue from the oropharynx to the tip is 10cms in length.
## Development
The anterior tongue is derived primarily from the first pharyngeal arch. The posterior tongue is derived primarily from the third pharyngeal arch. The second arch however has a substantial contribution during fetal development, but this later atrophies. The fourth arch may also contribute, depending upon how the boundaries of the tongue are defined.
The terminal sulcus, which separates the anterior and posterior tongue, is shaped like a V, with the tip of the V situated posteriorly. At the apex is the foramen caecum, which is the point where the embryological thyroid begins to descend.:990
# Function
## Taste
Chemicals that stimulate taste receptor cells are known as tastants. Once a tastant is dissolved in saliva, it can make contact with the plasma membrane of the gustatory hairs, which are the sites of taste transduction.
The tongue is equipped with many taste buds on its dorsal surface, and each taste bud is equipped with taste receptor cells that can sense particular classes of tastes. Distinct types of taste receptor cells respectively detect substances that are sweet, bitter, salty, sour, spicy, or taste of umami. Umami receptor cells are the least understood and accordingly are the type most intensively under research.
## Mastication
The tongue is also used for crushing food against the hard palate, during mastication. The epithelium on the tongue’s upper, or dorsal surface is keratinised. Consequently, the tongue can grind against the hard palate without being itself damaged or irritated.
## Swallowing
## Speech
# Clinical relevance
## Disease
After the gums, the tongue is the second most common soft tissue site for various pathologies in the oral cavity. Examples of pathological conditions of the tongue include glossitis (e.g. geographic tongue, median rhomboid glossitis), burning mouth syndrome, oral hairy leukoplakia, oral candidiasis and squamous cell carcinoma. Food debris, desquamated epithelial cells and bacteria often form a visible tongue coating. This coating has been identified as a major contributing factor in bad breath (halitosis), which can be managed by brushing the tongue gently with a toothbrush or using special oral hygiene instruments such as tongue scrapers or mouth brushes.
## Medical delivery
The sublingual region underneath the front of the tongue is a location where the oral mucosa is very thin, and underlain by a plexus of veins. This is an ideal location for introducing certain medications to the body. The sublingual route takes advantage of the highly vascular quality of the oral cavity, and allows for the speedy application of medication into the cardiovascular system, bypassing the gastrointestinal tract. This is the only convenient and efficacious route of administration (apart from I.V. administration) of nitroglycerin to a patient suffering chest pain from angina pectoris.
# Society and culture
## Figures of speech
The tongue can be used as a metonym for language, as in the phrase mother tongue. Many languages have the same word for "tongue" and "language".
A common temporary failure in word retrieval from memory is referred to as the tip-of-the-tongue phenomenon. The expression tongue in cheek refers to a statement that is not to be taken entirely seriously – something said or done with subtle ironic or sarcastic humour. A tongue twister is a phrase made specifically to be very difficult to pronounce. Aside from being a medical condition, "tongue-tied" means being unable to say what you want to due to confusion or restriction. The phrase "cat got your tongue" refers to when a person is speechless. To "bite one's tongue" is a phrase which describes holding back an opinion to avoid causing offence. A "slip of the tongue" refers to an unintentional utterance, such as a Freudian slip. Speaking in tongues is a common phrase used to describe glossolalia, which is to make smooth, language-resembling sounds that is no true spoken language itself. A deceptive person is said to have a forked tongue, and a smooth-talking person said to have a silver tongue.
## Gestures
Sticking one's tongue out at someone is considered a childish gesture of rudeness and/or defiance in many countries; the act may also have sexual connotations, depending on the way in which it is done. However, in Tibet it is considered a greeting. In 2009, a farmer from Fabriano, Italy was convicted and fined by the country's highest court for sticking his tongue out at a neighbor with whom he had been arguing. Proof of the affront had been captured with a cell phone camera. Blowing a raspberry can also be meant as a gesture of derision.
## Body art
Being a cultural custom for long time, tongue piercing and splitting has become quite common in western countries in recent decades, with up to one-fifth of young adults having at least one piece of body art in the tongue.
## As food
The tongues of some animals are consumed and sometimes considered delicacies. Hot tongue sandwiches are frequently found on menus in Kosher delicatessens in America. Taco de lengua (lengua being Spanish for tongue) is a taco filled with beef tongue, and is especially popular in Mexican cuisine. As part of Colombian gastronomy, Tongue in Sauce (Lengua en Salsa), is a dish prepared by frying the tongue, adding tomato sauce, onions and salt. Tongue can also be prepared as birria. Pig and beef tongue are consumed in Chinese cuisine. Duck tongues are sometimes employed in Szechuan dishes, while lamb's tongue is occasionally employed in Continental and contemporary American cooking. Fried cod "tongue" is a relatively common part of fish meals in Norway and Newfoundland. In Argentina and Uruguay cow tongue is cooked and served in vinegar (lengua a la vinagreta). In the Czech Republic and Poland, a pork tongue is considered a delicacy, and there are many ways of preparing it. In Eastern Slavic countries, pork and beef tongues are commonly consumed, boiled and garnished with horseradish or jelled; beef tongues fetch a significantly higher price and are considered more of a delicacy. In Alaska, cow tongues are among the more common.
Tongues of seals and whales have been eaten, sometimes in large quantities, by sealers and whalers, and in various times and places have been sold for food on shore.
# History
## Etymology
The word tongue derives from the Old English tunge, which comes from Proto-Germanic *tungōn. It has cognates in other Germanic languages — for example tonge in West Frisian, tong in Dutch/Afrikaans, Zunge in German, tunge in Danish/Norwegian and tunga in Icelandic/Faroese/Swedish. The ue ending of the word seems to be a fourteenth-century attempt to show "proper pronunciation", but it is "neither etymological nor phonetic". Some used the spelling tunge and tonge as late as the sixteenth century.
# Other animals
Most vertebrate animals have tongues. In mammals such as dogs and cats, the tongue is often used to clean the fur and body. The tongues of these species have a very rough texture which allows them to remove oils and parasites. A dog's tongue also acts as a heat regulator. As a dog increases its exercise the tongue will increase in size due to greater blood flow. The tongue hangs out of the dog's mouth and the moisture on the tongue will work to cool the bloodflow.
Some animals have tongues that are specially adapted for catching prey. For example, chameleons, frogs, and anteaters have prehensile tongues.
Many species of fish have small folds at the base of their mouths that might informally be called tongues, but they lack a muscular structure like the true tongues found in most tetrapods.
Other animals may have organs that are analogous to tongues, such as a butterfly's proboscis or a radula on a mollusc, but these are not homologous with the tongues found in vertebrates, and often have little resemblance in function, for example, butterflies do not lick with their proboscides; they suck through them, and the proboscis is not a single organ, but two jaws held together to form a tube.
# Additional Images | Tonsil
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
# Overview
The tongue is a muscular hydrostat on the floor of the mouth of most vertebrates that manipulates food for mastication. It is the primary organ of taste (gustation), as much of its upper surface is covered in taste buds. The tongue's upper surface is also covered in numerous lingual papillae. It is sensitive and kept moist by saliva, and is richly supplied with nerves and blood vessels. In humans a secondary function of the tongue is phonetic articulation. The tongue also serves as a natural means of cleaning the teeth.[1] The ability to perceive different tastes is not localised in different parts of the tongue, as is widely believed.[2] This error arose because of misinterpretation of some 19th-century research (see tongue map).
# Structure
The tongue is a muscular structure that forms part of the floor of the oral cavity. The left and right sides of the tongue are separated by the lingual septum. The human tongue is divided into anterior and posterior parts. The anterior part is the visible part situated at the front and makes up roughly two-thirds the length of the tongue. The posterior part is the part closest to the throat, roughly one-third of its length. These parts differ in terms of their embryological development and nerve supply. The two parts of the tongue are divided by the terminal sulcus.[3]:989–990
The anterior tongue is, at its apex, thin and narrow, it is directed forward against the lingual surfaces of the lower incisor teeth. The posterior part is, at its root, directed backward, and connected with the hyoid bone by the hyoglossi and genioglossi muscles and the hyoglossal membrane, with the epiglottis by three folds (glossoepiglottic) of mucous membrane, with the soft palate by the glossopalatine arches, and with the pharynx by the superior pharyngeal constrictor muscle and the mucous membrane. It also forms the anterior wall of the oropharynx.
In phonetics and phonology, a distinction is made between the tip of the tongue and the blade (the portion just behind the tip). Sounds made with the tongue tip are said to be apical, while those made with the tongue blade are said to be laminal.
## Muscles
The eight muscles of the human tongue are classified as either intrinsic or extrinsic. The four intrinsic muscles act to change the shape of the tongue, and are not attached to any bone. The four extrinsic muscles act to change the position of the tongue, and are anchored to bone.
- Coronal section of tongue, showing intrinsic muscles
- Lateral view of the tongue, with extrinsic muscles highlighted.
### Extrinsic
The extrinsic muscles originate from bone and extend to the tongue. Their main functions are altering the tongue's position allowing for protrusion, retraction, and side-to-side movement.[3]:991
- Genioglossus, which arises from the mandible and protrudes the tongue. It is also known as the "safety muscle" of the tongue since it is the only muscle having the forward action.
- Hyoglossus, which arises from the hyoid bone and depresses the tongue
- Styloglossus, which arises from the styloid process of the temporal bone and elevates and retracts the tongue
- Palatoglossus, which arises from the palatine aponeurosis, and depresses the soft palate, moves the palatoglossal fold towards the midline, and elevates the back of the tongue.
### Intrinsic
Four paired intrinsic muscles of the tongue originate and insert within the tongue, running along its length. These muscles alter the shape of the tongue by: lengthening and shortening it, curling and uncurling its apex and edges, and flattening and rounding its surface. This provides shape, and helps facilitate speech, swallowing, and eating.[3]:991
- The superior longitudinal muscle runs along the superior surface of the tongue under the mucous membrane, and elevates, assists in retraction of, or deviates the tip of the tongue. It originates near the epiglottis, the hyoid bone, from the median fibrous septum.
- The inferior longitudinal muscle lines the sides of the tongue, and is joined to the styloglossus muscle.
- The vertical muscle is located in the middle of the tongue, and joins the superior and inferior longitudinal muscles.
- The transverse muscle divides the tongue at the middle, and is attached to the mucous membranes that run along the sides.
## Blood supply
The tongue receives its blood supply primarily from the lingual artery, a branch of the external carotid artery. The lingual veins, drain into the internal jugular vein. The floor of the mouth also receives its blood supply from the lingual artery.[3]:993–994 There is also a secondary blood supply to the tongue from the tonsillar branch of the facial artery and the ascending pharyngeal artery.
An area in the neck sometimes called Pirogov's triangle is formed by the intermediate tendon of the digastric muscle, the posterior border of the mylohyoid muscle, and the hypoglossal nerve.[4][5] The lingual artery is a good place to stop severe hemorrage from the tongue.
## Innervation
Innervation of the tongue consists of motor fibers, special sensory fibers for taste, and general sensory fibers for sensation.[3]:994–5
- Motor supply for all intrinsic and extrinsic muscles of the tongue is supplied by efferent motor nerve fibers from the hypoglossal nerve (CN XII), with the exception of the palatoglossus. The palatoglossus is innervated by the vagus nerve (CN X).[3]:995
Innervation of taste and sensation is different for the anterior and posterior part of the tongue because they are derived from different embryological structures (pharyngeal arch 1 and pharyngeal arch 3 and 4, respectively).[6]
- Anterior two thirds of tongue (anterior to the vallate papillae):
Taste: chorda tympani branch of the facial nerve (CN VII) via special visceral afferent fibers
Sensation: lingual branch of the mandibular division (V3) of the trigeminal nerve (CN V) via general somatic afferent fibers
- Taste: chorda tympani branch of the facial nerve (CN VII) via special visceral afferent fibers
- Sensation: lingual branch of the mandibular division (V3) of the trigeminal nerve (CN V) via general somatic afferent fibers
- Posterior one third of tongue:
Taste and sensation: glossopharyngeal nerve (CN IX) via a mixture of special and general visceral afferent fibers
- Taste and sensation: glossopharyngeal nerve (CN IX) via a mixture of special and general visceral afferent fibers
## Histology
The tongue is covered with numerous taste buds, and filiform, fungiform, vallate and foliate, lingual papillae.[3]:990
## Length
The average length of the human tongue from the oropharynx to the tip is 10cms in length.[7]
## Development
The anterior tongue is derived primarily from the first pharyngeal arch. The posterior tongue is derived primarily from the third pharyngeal arch. The second arch however has a substantial contribution during fetal development, but this later atrophies. The fourth arch may also contribute, depending upon how the boundaries of the tongue are defined.
The terminal sulcus, which separates the anterior and posterior tongue, is shaped like a V, with the tip of the V situated posteriorly. At the apex is the foramen caecum, which is the point where the embryological thyroid begins to descend.[3]:990
# Function
## Taste
Chemicals that stimulate taste receptor cells are known as tastants. Once a tastant is dissolved in saliva, it can make contact with the plasma membrane of the gustatory hairs, which are the sites of taste transduction.[8]
The tongue is equipped with many taste buds on its dorsal surface, and each taste bud is equipped with taste receptor cells that can sense particular classes of tastes. Distinct types of taste receptor cells respectively detect substances that are sweet, bitter, salty, sour, spicy, or taste of umami.[9] Umami receptor cells are the least understood and accordingly are the type most intensively under research.[10]
## Mastication
The tongue is also used for crushing food against the hard palate, during mastication. The epithelium on the tongue’s upper, or dorsal surface is keratinised. Consequently, the tongue can grind against the hard palate without being itself damaged or irritated.[11]
## Swallowing
## Speech
# Clinical relevance
## Disease
After the gums, the tongue is the second most common soft tissue site for various pathologies in the oral cavity.[medical citation needed] Examples of pathological conditions of the tongue include glossitis (e.g. geographic tongue, median rhomboid glossitis), burning mouth syndrome, oral hairy leukoplakia, oral candidiasis and squamous cell carcinoma.[12] Food debris, desquamated epithelial cells and bacteria often form a visible tongue coating.[13] This coating has been identified as a major contributing factor in bad breath (halitosis),[13] which can be managed by brushing the tongue gently with a toothbrush or using special oral hygiene instruments such as tongue scrapers or mouth brushes.[14]
## Medical delivery
The sublingual region underneath the front of the tongue is a location where the oral mucosa is very thin, and underlain by a plexus of veins. This is an ideal location for introducing certain medications to the body. The sublingual route takes advantage of the highly vascular quality of the oral cavity, and allows for the speedy application of medication into the cardiovascular system, bypassing the gastrointestinal tract. This is the only convenient and efficacious route of administration (apart from I.V. administration) of nitroglycerin to a patient suffering chest pain from angina pectoris.
# Society and culture
## Figures of speech
The tongue can be used as a metonym for language, as in the phrase mother tongue. Many languages[15] have the same word for "tongue" and "language".
A common temporary failure in word retrieval from memory is referred to as the tip-of-the-tongue phenomenon. The expression tongue in cheek refers to a statement that is not to be taken entirely seriously – something said or done with subtle ironic or sarcastic humour. A tongue twister is a phrase made specifically to be very difficult to pronounce. Aside from being a medical condition, "tongue-tied" means being unable to say what you want to due to confusion or restriction. The phrase "cat got your tongue" refers to when a person is speechless. To "bite one's tongue" is a phrase which describes holding back an opinion to avoid causing offence. A "slip of the tongue" refers to an unintentional utterance, such as a Freudian slip. Speaking in tongues is a common phrase used to describe glossolalia, which is to make smooth, language-resembling sounds that is no true spoken language itself. A deceptive person is said to have a forked tongue, and a smooth-talking person said to have a silver tongue.
## Gestures
Sticking one's tongue out at someone is considered a childish gesture of rudeness and/or defiance in many countries; the act may also have sexual connotations, depending on the way in which it is done. However, in Tibet it is considered a greeting.[16] In 2009, a farmer from Fabriano, Italy was convicted and fined by the country's highest court for sticking his tongue out at a neighbor with whom he had been arguing. Proof of the affront had been captured with a cell phone camera.[17] Blowing a raspberry can also be meant as a gesture of derision.[citation needed]
## Body art
Being a cultural custom for long time, tongue piercing and splitting has become quite common in western countries in recent decades, with up to one-fifth of young adults having at least one piece of body art in the tongue.[18]
## As food
The tongues of some animals are consumed and sometimes considered delicacies. Hot tongue sandwiches are frequently found on menus in Kosher delicatessens in America. Taco de lengua (lengua being Spanish for tongue) is a taco filled with beef tongue, and is especially popular in Mexican cuisine. As part of Colombian gastronomy, Tongue in Sauce (Lengua en Salsa), is a dish prepared by frying the tongue, adding tomato sauce, onions and salt. Tongue can also be prepared as birria. Pig and beef tongue are consumed in Chinese cuisine. Duck tongues are sometimes employed in Szechuan dishes, while lamb's tongue is occasionally employed in Continental and contemporary American cooking. Fried cod "tongue" is a relatively common part of fish meals in Norway and Newfoundland. In Argentina and Uruguay cow tongue is cooked and served in vinegar (lengua a la vinagreta). In the Czech Republic and Poland, a pork tongue is considered a delicacy, and there are many ways of preparing it. In Eastern Slavic countries, pork and beef tongues are commonly consumed, boiled and garnished with horseradish or jelled; beef tongues fetch a significantly higher price and are considered more of a delicacy. In Alaska, cow tongues are among the more common.
Tongues of seals and whales have been eaten, sometimes in large quantities, by sealers and whalers, and in various times and places have been sold for food on shore.[19]
# History
## Etymology
The word tongue derives from the Old English tunge, which comes from Proto-Germanic *tungōn.[20] It has cognates in other Germanic languages — for example tonge in West Frisian, tong in Dutch/Afrikaans, Zunge in German, tunge in Danish/Norwegian and tunga in Icelandic/Faroese/Swedish. The ue ending of the word seems to be a fourteenth-century attempt to show "proper pronunciation", but it is "neither etymological nor phonetic".[20] Some used the spelling tunge and tonge as late as the sixteenth century.
# Other animals
Most vertebrate animals have tongues. In mammals such as dogs and cats, the tongue is often used to clean the fur and body. The tongues of these species have a very rough texture which allows them to remove oils and parasites. A dog's tongue also acts as a heat regulator. As a dog increases its exercise the tongue will increase in size due to greater blood flow. The tongue hangs out of the dog's mouth and the moisture on the tongue will work to cool the bloodflow.[21][22]
Some animals have tongues that are specially adapted for catching prey. For example, chameleons, frogs, and anteaters have prehensile tongues.
Many species of fish have small folds at the base of their mouths that might informally be called tongues, but they lack a muscular structure like the true tongues found in most tetrapods.[23][24]
Other animals may have organs that are analogous to tongues, such as a butterfly's proboscis or a radula on a mollusc, but these are not homologous with the tongues found in vertebrates, and often have little resemblance in function, for example, butterflies do not lick with their proboscides; they suck through them, and the proboscis is not a single organ, but two jaws held together to form a tube.[25]
# Additional Images | https://www.wikidoc.org/index.php/Tonsil | |
87ec9963545b31fa3d2bd3fda3b559901f351f5c | wikidoc | Torpor | Torpor
# Overview
Torpor is a (usually short-term) state of decreased physiological activity in an animal, usually characterized by a reduced body temperature and rate of metabolism. Animals that go through torpor include birds (even tiny hummingbirds) - notably Cypselomorphae - and some small mammals such as bats. During the active part of their day, these animals maintain normal body temperature and activity levels, but their body temperature drops during a portion of the day (usually night) to conserve energy. Torpor is often used to help animals survive during periods of colder temperatures, since it allows the organism to save the amount of energy that would normally be used to maintain a high body temperature.
Torpor may extend for a longer period of time. Some animals such as groundhogs, chipmunks, ground squirrels and jumping mice enter this intensely deep state of hibernation for the duration of the winter. Lungfish switch to the torpor state if their pool dries out; tenrecs switch to the torpor state if food is scarce during the summer (in Madagascar). Black bears, although often thought of as hibernators, do not truly enter a state of torpor: While their body temperatures lower along with respiration and heartbeat, they do not decrease as significantly as most animals in a state of torpor. Still, there is much debate about this within the scientific community: Some feel that black bears are true hibernators that employ a more advanced form of hibernation.
# Other uses of the word
- Torpor is alternately used as a reference to any non-physiological state of inactivity. As an example, recently naturalists have learned that the female crocodile enters a deep torpor without aggression during their short egg laying period.
- This definition is also commonly used to describe the "chill out" effects of a number of psychotropic drugs, such as psychedelic mushrooms and LSD. However, these psychedelics actually raise body temperature.
- Torpor is also used in vampire mythology, to describe the state that a vampire enters during the daylight hours. Thus, the vampire needs to have or find a safe and secluded spot that is shielded from sunlight. In some mythologies, the vampire also uses a guardian to protect him during the state of torpor. | Torpor
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
# Overview
Torpor is a (usually short-term) state of decreased physiological activity in an animal, usually characterized by a reduced body temperature and rate of metabolism. Animals that go through torpor include birds (even tiny hummingbirds) - notably Cypselomorphae - and some small mammals such as bats. During the active part of their day, these animals maintain normal body temperature and activity levels, but their body temperature drops during a portion of the day (usually night) to conserve energy. Torpor is often used to help animals survive during periods of colder temperatures, since it allows the organism to save the amount of energy that would normally be used to maintain a high body temperature.
Torpor may extend for a longer period of time. Some animals such as groundhogs, chipmunks, ground squirrels and jumping mice enter this intensely deep state of hibernation for the duration of the winter. Lungfish switch to the torpor state if their pool dries out; tenrecs switch to the torpor state if food is scarce during the summer (in Madagascar). Black bears, although often thought of as hibernators, do not truly enter a state of torpor: While their body temperatures lower along with respiration and heartbeat, they do not decrease as significantly as most animals in a state of torpor. Still, there is much debate about this within the scientific community: Some feel that black bears are true hibernators that employ a more advanced form of hibernation.
# Other uses of the word
- Torpor is alternately used as a reference to any non-physiological state of inactivity. As an example, recently naturalists have learned that the female crocodile enters a deep torpor without aggression during their short egg laying period.
- This definition is also commonly used to describe the "chill out" effects of a number of psychotropic drugs, such as psychedelic mushrooms and LSD. However, these psychedelics actually raise body temperature.
- Torpor is also used in vampire mythology, to describe the state that a vampire enters during the daylight hours. Thus, the vampire needs to have or find a safe and secluded spot that is shielded from sunlight. In some mythologies, the vampire also uses a guardian to protect him during the state of torpor. | https://www.wikidoc.org/index.php/Torpor | |
7c8ac1df9533c64925e8c5db57fd43d525dc5bc7 | wikidoc | Torque | Torque
# Overview
In physics, a torque (τ) (also called a moment) is a vector that measures the tendency of a force to rotate an object about some axis (center). The magnitude of a torque is defined as force times the length of the lever arm (radius). Just as a force is a push or a pull, a torque can be thought of as a twist.
The SI unit for torque is newton meters (N m). In U.S. customary units, it is measured in foot pounds (ft·lbf) (also known as 'pound feet'). The symbol for torque is τ, the Greek letter tau.
# History
The concept of torque, also called moment or couple, originated with the studies of Archimedes on levers. The rotational analogues of force, mass, and acceleration are torque, moment of inertia, and angular acceleration, respectively.
# Explanation
The force applied to a lever, multiplied by its distance from the lever's fulcrum, is its torque. For example, a force of three newtons applied two meters from the fulcrum exerts the same torque as one newton applied six meters from the fulcrum. This assumes the force is in a direction at right angles to the straight lever. The direction of the torque can be determined by using the right hand rule: Using your right hand, curl your fingers in the direction of rotation, and stick your thumb out so it is aligned with the axis of rotation. Your thumb points in the direction of the torque vector.
Mathematically, the torque on a particle (which has the position r in some reference frame) can be defined as the cross product:
where
The torque on a body determines the rate of change of its angular momentum,
where
As can be seen from either of these relationships, torque is a vector, which points along the axis of the rotation it would tend to cause.
# Units
Torque has dimensions of force times distance and the SI unit of torque is the "newton meter" (N m). Even though the order of "newton" and "meter" are mathematically interchangeable, the BIPM (Bureau International des Poids et Mesures) specifies that the order should be N m not m N. N·m is also acceptable.
The joule, which is the SI unit for energy or work, is also defined as 1 N m, but this unit is not used for torque. Since energy can be thought of as the result of "force times distance", energy is always a scalar whereas torque is "force cross distance" and so is a (pseudo) vector-valued quantity. Of course, the dimensional equivalence of these units is not simply a coincidence; a torque of 1 N m applied through a full revolution will require an energy of exactly 2π joules. Mathematically,
where
Other non-SI units of torque include "pound-force-feet" or "foot-pounds-force" or "ounce-force-inches" or "meter-kilograms-force".
# Extended units in relation with rotation angles
As a consequence of the previous equation, if you introduce the radian (rad) as part of the dimensional units in the SI units system, the torque could be measured using "newton meters per radian" (N m/rad), or "joules per radian" (J/rad), while the energy needed and spent to perform the rotation would be measured simply in "newton meters" or "joules".
In the strict SI system, angles are not given any dimensional unit, because they do not designate physical quantities, despite the fact that they are measurable indirectly simply by dividing two distances (the arc length and the radius): one way to conciliate the two systems would be to say that arc lengths are not measures of distances (given they are not measured over a straight line, and a full circle rotation returns to the same position, i.e. a null distance). So arc lengths should be measured in "radian meter" (rad·m), differently from straight segment lengths in "meters" (m). In such extended SI system, the perimeter of a circle whose radius is one meter, will be two pi rad·m, and not just two pi meters.
If you apply this measure to a rotating wheel in contact with a plane surface, the center of the wheel will move across a distance measured in meters with the same value, only if the contact is efficient and the wheel does not slide on it: this does not happen in practice, unless the surface of contact is constrained and is then not perfectly plane (and can resist to the horizontal linear forces applied to the irregularities of the pseudo-plane surface of movement and to the surface of the pseudo-circular rotating wheel); but then the system generates friction that loses some energy spent by the engine: this lost energy does not change the measurement of the torque or the total energy spent in the system but the effective distance that has been made by the center of the wheel.
The difference between the efficient energy spent by the engine and the energy produced in the linear movement is lost in friction and sliding, and this explains why, when applying the same non-null torque constantly to the wheel, so that the wheel moves at a constant speed according to the surface in contact, there may be no acceleration of the center of the wheel: in that case, the energy spent will be directly proportional to the distance made by the center of the wheel, and equal to the energy lost in the system by friction and sliding.
For this reason, when measuring the effective power produced by a rotating engine and the energy spent in the system to generate a movement, you will often need to take into account the angle of rotation, and then, adding the radian in the unit system is necessary as well as making a difference between the measurement of arcs (in radian meter) and the measurement of straight segment distances (in meters), as a way to effectively compute the efficiency of the mobile system and the capacity of a motor engine to convert between rotational power (in radian watt) and linear power (in watts): in a friction-free ideal system, the two measurements would have equal value, but this does not happen in practice, each conversion losing energy in friction (it's easier to limit all losses of energy caused by sliding, by introducing mechanical constraints of forms on the surfaces of contacts).
Depending on works, the extended units including radians as a fundamental dimension may or may not be used.
# Special cases and other facts
## Moment arm formula
A very useful special case, often given as the definition of torque in fields other than physics, is as follows:
The construction of the "moment arm" is shown in the figure below, along with the vectors r and F mentioned above. The problem with this definition is that it does not give the direction of the torque but only the magnitude, and hence it is difficult to use in three-dimensional cases. If the force is perpendicular to the displacement vector r, the moment arm will be equal to the distance to the centre, and torque will be a maximum for the given force. The equation for the magnitude of a torque arising from a perpendicular force:
For example, if a person places a force of 10 N on a spanner which is 0.5 m long, the torque will be 5 N m, assuming that the person pulls the spanner by applying force perpendicular to the spanner.
## Force at an angle
If a force of magnitude F is at an angle θ from the displacement arm of length r (and within the plane perpendicular to the rotation axis), then from the definition of cross product, the magnitude of the torque arising is:
## Static equilibrium
For an object to be in static equilibrium, not only must the sum of the forces be zero, but also the sum of the torques (moments) about any point. For a two-dimensional situation with horizontal and vertical forces, the sum of the forces requirement is two equations: ΣH = 0 and ΣV = 0, and the torque a third equation: Στ = 0. That is, to solve statically determinate equilibrium problems in two-dimensions, we use three equations.
## Torque as a function of time
Torque is the time-derivative of angular momentum, just as force is the time derivative of linear momentum:
where
Angular momentum on a rigid body can be written in terms of its moment of inertia \boldsymbol I \,\! and its angular velocity \boldsymbol{\omega}:
so if \boldsymbol I \,\! is constant,
where α is angular acceleration, a quantity usually measured in radians per second squared.
# Machine torque
Torque is part of the basic specification of an engine: the power output of an engine is expressed as its torque multiplied by its rotational speed. Internal-combustion engines produce useful torque only over a limited range of rotational speeds (typically from around 1,000–6,000 rpm for a small car). The varying torque output over that range can be measured with a dynamometer, and shown as a torque curve. The peak of that torque curve usually occurs somewhat below the overall power peak. The torque peak cannot, by definition, appear at higher rpm than the power peak.
Understanding the relationship between torque, power and engine speed is vital in automotive engineering, concerned as it is with transmitting power from the engine through the drive train to the wheels. Typically power is a function of torque and engine speed. The gearing of the drive train must be chosen appropriately to make the most of the motor's torque characteristics.
Steam engines and electric motors tend to produce maximum torque close to zero rpm, with the torque diminishing as rotational speed rises (due to increasing friction and other constraints). Therefore, these types of engines usually have quite different types of drivetrains from internal combustion engines.
Torque is also the easiest way to explain mechanical advantage in just about every simple machine.
# Relationship between torque, power and energy
If a force is allowed to act through a distance, it is doing mechanical work. Similarly, if torque is allowed to act through a rotational distance, it is doing work. Power is the work per unit time. However, time and rotational distance are related by the angular speed where each revolution results in the circumference of the circle being travelled by the force that is generating the torque. The power injected by the applied torque may be calculated as:
On the right hand side, this is a scalar product of two vectors, giving a scalar on the left hand side of the equation. Mathematically, the equation may be rearranged to compute torque for a given power output. Note that the power injected by the torque depends only on the instantaneous angular speed - not on whether the angular speed increases, decreases, or remains constant while the torque is being applied (this is equivalent to the linear case where the power injected by a force depends only on the instantaneous speed - not on the resulting acceleration, if any).
In practice, this relationship can be observed in power stations which are connected to a large electrical power grid. In such an arrangement, the generator's angular speed is fixed by the grid's frequency, and the power output of the plant is determined by the torque applied to the generator's axis of rotation.
Consistent units must be used. For metric SI units power is watts, torque is newton meters and angular speed is radians per second (not rpm and not revolutions per second).
Also, the unit newton meter is dimensionally equivalent to the joule, which is the unit of energy. However, in the case of torque, the unit is assigned to a vector, whereas for energy, it is assigned to a scalar.
## Conversion to other units
For different units of power, torque, or angular speed, a conversion factor must be inserted into the equation. Also, if rotational speed (revolutions per time) is used in place of angular speed (radians per time), a conversion factor of 2 \pi must be added because there are 2 \pi radians in a revolution:
where rotational speed is in revolutions per unit time.
Useful formula in SI units:
where 60,000 comes from 60 seconds per minute times 1000 watts per kilowatt.
Some people (e.g. American automotive engineers) use horsepower (imperial mechanical) for power, foot-pounds (lbf·ft) for torque and rpm (revolutions per minute) for angular speed. This results in the formula changing to:
This conversion factor is approximate because the transcendental number π appears in it; a more precise value is 5252.113 122 032 55... It comes from 33,000 (ft·lbf./min) / 2π (radians/revolution). It also changes with the definition of the horsepower, of course; for example, using the metric horsepower, it becomes ~5180.
Use of other units (e.g. BTU/h for power) would require a different custom conversion factor.
## Derivation
For a rotating object, the linear distance covered at the circumference in a radian of rotation is the product of the radius with the angular speed. That is: linear speed = radius x angular speed. By definition, linear distance=linear speed x time=radius x angular speed x time.
By the definition of torque: torque=force x radius. We can rearrange this to determine force=torque/radius. These two values can be substituted into the definition of power:
The radius r and time t have dropped out of the equation. However angular speed must be in radians, by the assumed direct relationship between linear speed and angular speed at the beginning of the derivation. If the rotational speed is measured in revolutions per unit of time, the linear speed and distance are increased proportionately by 2 \pi in the above derivation to give:
If torque is in lbf·ft and rotational speed in revolutions per minute, the above equation gives power in ft·lbf/min. The horsepower form of the equation is then derived by applying the conversion factor 33,000 ft·lbf/min per horsepower:
because 5252.113555... = \frac {33,000} {2 \pi} \,. | Torque
# Overview
In physics, a torque (τ) (also called a moment) is a vector that measures the tendency of a force to rotate an object about some axis [1] (center). The magnitude of a torque is defined as force times the length of the lever arm [2] (radius). Just as a force is a push or a pull, a torque can be thought of as a twist.
The SI unit for torque is newton meters (N m). In U.S. customary units, it is measured in foot pounds (ft·lbf) (also known as 'pound feet'). The symbol for torque is τ, the Greek letter tau.
# History
The concept of torque, also called moment or couple, originated with the studies of Archimedes on levers. The rotational analogues of force, mass, and acceleration are torque, moment of inertia, and angular acceleration, respectively.
# Explanation
The force applied to a lever, multiplied by its distance from the lever's fulcrum, is its torque. For example, a force of three newtons applied two meters from the fulcrum exerts the same torque as one newton applied six meters from the fulcrum. This assumes the force is in a direction at right angles to the straight lever. The direction of the torque can be determined by using the right hand rule: Using your right hand, curl your fingers in the direction of rotation, and stick your thumb out so it is aligned with the axis of rotation. Your thumb points in the direction of the torque vector.[3]
Mathematically, the torque on a particle (which has the position r in some reference frame) can be defined as the cross product:
where
The torque on a body determines the rate of change of its angular momentum,
where
As can be seen from either of these relationships, torque is a vector, which points along the axis of the rotation it would tend to cause.
# Units
Torque has dimensions of force times distance and the SI unit of torque is the "newton meter" (N m).[4] Even though the order of "newton" and "meter" are mathematically interchangeable, the BIPM (Bureau International des Poids et Mesures) specifies that the order should be N m not m N. N·m is also acceptable.[5]
The joule, which is the SI unit for energy or work, is also defined as 1 N m, but this unit is not used for torque. Since energy can be thought of as the result of "force times distance", energy is always a scalar whereas torque is "force cross distance" and so is a (pseudo) vector-valued quantity. Of course, the dimensional equivalence of these units is not simply a coincidence; a torque of 1 N m applied through a full revolution will require an energy of exactly 2π joules. Mathematically,
where
Other non-SI units of torque include "pound-force-feet" or "foot-pounds-force" or "ounce-force-inches" or "meter-kilograms-force".
# Extended units in relation with rotation angles
As a consequence of the previous equation, if you introduce the radian (rad) as part of the dimensional units in the SI units system, the torque could be measured using "newton meters per radian" (N m/rad), or "joules per radian" (J/rad), while the energy needed and spent to perform the rotation would be measured simply in "newton meters" or "joules".
In the strict SI system, angles are not given any dimensional unit, because they do not designate physical quantities, despite the fact that they are measurable indirectly simply by dividing two distances (the arc length and the radius): one way to conciliate the two systems would be to say that arc lengths are not measures of distances (given they are not measured over a straight line, and a full circle rotation returns to the same position, i.e. a null distance). So arc lengths should be measured in "radian meter" (rad·m), differently from straight segment lengths in "meters" (m). In such extended SI system, the perimeter of a circle whose radius is one meter, will be two pi rad·m, and not just two pi meters.
If you apply this measure to a rotating wheel in contact with a plane surface, the center of the wheel will move across a distance measured in meters with the same value, only if the contact is efficient and the wheel does not slide on it: this does not happen in practice, unless the surface of contact is constrained and is then not perfectly plane (and can resist to the horizontal linear forces applied to the irregularities of the pseudo-plane surface of movement and to the surface of the pseudo-circular rotating wheel); but then the system generates friction that loses some energy spent by the engine: this lost energy does not change the measurement of the torque or the total energy spent in the system but the effective distance that has been made by the center of the wheel.
The difference between the efficient energy spent by the engine and the energy produced in the linear movement is lost in friction and sliding, and this explains why, when applying the same non-null torque constantly to the wheel, so that the wheel moves at a constant speed according to the surface in contact, there may be no acceleration of the center of the wheel: in that case, the energy spent will be directly proportional to the distance made by the center of the wheel, and equal to the energy lost in the system by friction and sliding.
For this reason, when measuring the effective power produced by a rotating engine and the energy spent in the system to generate a movement, you will often need to take into account the angle of rotation, and then, adding the radian in the unit system is necessary as well as making a difference between the measurement of arcs (in radian meter) and the measurement of straight segment distances (in meters), as a way to effectively compute the efficiency of the mobile system and the capacity of a motor engine to convert between rotational power (in radian watt) and linear power (in watts): in a friction-free ideal system, the two measurements would have equal value, but this does not happen in practice, each conversion losing energy in friction (it's easier to limit all losses of energy caused by sliding, by introducing mechanical constraints of forms on the surfaces of contacts).
Depending on works, the extended units including radians as a fundamental dimension may or may not be used.
# Special cases and other facts
## Moment arm formula
A very useful special case, often given as the definition of torque in fields other than physics, is as follows:
The construction of the "moment arm" is shown in the figure below, along with the vectors r and F mentioned above. The problem with this definition is that it does not give the direction of the torque but only the magnitude, and hence it is difficult to use in three-dimensional cases. If the force is perpendicular to the displacement vector r, the moment arm will be equal to the distance to the centre, and torque will be a maximum for the given force. The equation for the magnitude of a torque arising from a perpendicular force:
For example, if a person places a force of 10 N on a spanner which is 0.5 m long, the torque will be 5 N m, assuming that the person pulls the spanner by applying force perpendicular to the spanner.
## Force at an angle
If a force of magnitude F is at an angle θ from the displacement arm of length r (and within the plane perpendicular to the rotation axis), then from the definition of cross product, the magnitude of the torque arising is:
## Static equilibrium
For an object to be in static equilibrium, not only must the sum of the forces be zero, but also the sum of the torques (moments) about any point. For a two-dimensional situation with horizontal and vertical forces, the sum of the forces requirement is two equations: ΣH = 0 and ΣV = 0, and the torque a third equation: Στ = 0. That is, to solve statically determinate equilibrium problems in two-dimensions, we use three equations.
## Torque as a function of time
Torque is the time-derivative of angular momentum, just as force is the time derivative of linear momentum:
where
Angular momentum on a rigid body can be written in terms of its moment of inertia <math>\boldsymbol I \,\!</math> and its angular velocity <math>\boldsymbol{\omega}</math>:
so if <math>\boldsymbol I \,\!</math> is constant,
where α is angular acceleration, a quantity usually measured in radians per second squared.
# Machine torque
Torque is part of the basic specification of an engine: the power output of an engine is expressed as its torque multiplied by its rotational speed. Internal-combustion engines produce useful torque only over a limited range of rotational speeds (typically from around 1,000–6,000 rpm for a small car). The varying torque output over that range can be measured with a dynamometer, and shown as a torque curve. The peak of that torque curve usually occurs somewhat below the overall power peak. The torque peak cannot, by definition, appear at higher rpm than the power peak.
Understanding the relationship between torque, power and engine speed is vital in automotive engineering, concerned as it is with transmitting power from the engine through the drive train to the wheels. Typically power is a function of torque and engine speed. The gearing of the drive train must be chosen appropriately to make the most of the motor's torque characteristics.
Steam engines and electric motors tend to produce maximum torque close to zero rpm, with the torque diminishing as rotational speed rises (due to increasing friction and other constraints). Therefore, these types of engines usually have quite different types of drivetrains from internal combustion engines.
Torque is also the easiest way to explain mechanical advantage in just about every simple machine.[citation needed]
# Relationship between torque, power and energy
If a force is allowed to act through a distance, it is doing mechanical work. Similarly, if torque is allowed to act through a rotational distance, it is doing work. Power is the work per unit time. However, time and rotational distance are related by the angular speed where each revolution results in the circumference of the circle being travelled by the force that is generating the torque. The power injected by the applied torque may be calculated as:
On the right hand side, this is a scalar product of two vectors, giving a scalar on the left hand side of the equation. Mathematically, the equation may be rearranged to compute torque for a given power output. Note that the power injected by the torque depends only on the instantaneous angular speed - not on whether the angular speed increases, decreases, or remains constant while the torque is being applied (this is equivalent to the linear case where the power injected by a force depends only on the instantaneous speed - not on the resulting acceleration, if any).
In practice, this relationship can be observed in power stations which are connected to a large electrical power grid. In such an arrangement, the generator's angular speed is fixed by the grid's frequency, and the power output of the plant is determined by the torque applied to the generator's axis of rotation.
Consistent units must be used. For metric SI units power is watts, torque is newton meters and angular speed is radians per second (not rpm and not revolutions per second).
Also, the unit newton meter is dimensionally equivalent to the joule, which is the unit of energy. However, in the case of torque, the unit is assigned to a vector, whereas for energy, it is assigned to a scalar.
## Conversion to other units
For different units of power, torque, or angular speed, a conversion factor must be inserted into the equation. Also, if rotational speed (revolutions per time) is used in place of angular speed (radians per time), a conversion factor of <math>2 \pi</math> must be added because there are <math>2 \pi</math> radians in a revolution:
where rotational speed is in revolutions per unit time.
Useful formula in SI units:
where 60,000 comes from 60 seconds per minute times 1000 watts per kilowatt.
Some people (e.g. American automotive engineers) use horsepower (imperial mechanical) for power, foot-pounds (lbf·ft) for torque and rpm (revolutions per minute) for angular speed. This results in the formula changing to:
This conversion factor is approximate because the transcendental number π appears in it; a more precise value is 5252.113 122 032 55... It comes from 33,000 (ft·lbf./min) / 2π (radians/revolution). It also changes with the definition of the horsepower, of course; for example, using the metric horsepower, it becomes ~5180.
Use of other units (e.g. BTU/h for power) would require a different custom conversion factor.
## Derivation
For a rotating object, the linear distance covered at the circumference in a radian of rotation is the product of the radius with the angular speed. That is: linear speed = radius x angular speed. By definition, linear distance=linear speed x time=radius x angular speed x time.
By the definition of torque: torque=force x radius. We can rearrange this to determine force=torque/radius. These two values can be substituted into the definition of power:
The radius r and time t have dropped out of the equation. However angular speed must be in radians, by the assumed direct relationship between linear speed and angular speed at the beginning of the derivation. If the rotational speed is measured in revolutions per unit of time, the linear speed and distance are increased proportionately by <math>2 \pi</math> in the above derivation to give:
If torque is in lbf·ft and rotational speed in revolutions per minute, the above equation gives power in ft·lbf/min. The horsepower form of the equation is then derived by applying the conversion factor 33,000 ft·lbf/min per horsepower:
because <math>5252.113555... = \frac {33,000} {2 \pi} \,</math>. | https://www.wikidoc.org/index.php/Torque | |
f4665a1a285ed3a52d8529d52c1ca41cd5a0a7f2 | wikidoc | Triage | Triage
# Overview
Triage is a system of sorting patients according to need when resources are insufficient for all to be treated. The term comes from the French tri (meaning sort). There are two kinds: simple triage and advanced triage.
# Classification
Simple triage is used in a scene of mass casualty, in order to sort patients into those who need critical attention and immediate transport to the hospital and those with less serious injuries. This step is required before transportation becomes available. The categorization of patients based on the severity of their injuries can be aided with the use of printed triage tags or colored flagging.
In advanced triage, doctors may decide that some seriously injured people should not receive advanced care because they are unlikely to survive. Advanced care will be used on patients with less severe injuries. Because treatment is intentionally withheld from patients with certain injuries, Advanced triage has ethical implications. It is used to divert scarce resources away from patients with little chance of survival in order to increase the chances of survival of others who are more likely to survive.
In Western Europe, the criterion used for this category of patient is a trauma score of consistently at or below 3. This can be determined by using the triage Revised Trauma Score (TRTS), a medically validated scoring system incorporated in some triage cards.
The use of advanced triage may become necessary when medical professionals decide that the medical resources available are not sufficient to treat all the people who need help. This has happened in disasters such as volcanoes, thunderstorms, and rail accidents. In these cases some percentage of patients will die regardless of medical care because of the severity of their injuries. Others would live if given immediate medical care, but would die without it.
In this extreme case, any medical care given to people doomed to die can be considered to be care withdrawn from people who might live if they had been given it. It becomes the task of the disaster medical authorities to put aside some victims, to avoid saving one life at the expense of several others.
Triage is now also applied in system development. Requirements and design options are triaged to avoid wasting effort on ideas that will obviously never succeed.
# Simple Triage and Rapid Treatment
S.T.A.R.T. (Simple Triage and Rapid Treatment) is a simple triage system that can be performed by lightly-trained lay and emergency personnel in emergencies.
It is not intended to supersede or instruct medical personnel or techniques.
It may serve as an instructive example, and has been (2003) taught to California emergency workers for use in earthquakes. It was developed at Hoag Hospital in Newport Beach, California for use by emergency services It has been field-proven in mass casualty incidents such as train wrecks and bus accidents, though it was developed for use by CERTs and firemen after earthquakes.
Triage separates the injured into four groups: The deceased who are beyond help, the injured who can be helped by immediate transportation, the injured whose transport can be delayed, and those with minor injuries, who need help less urgently. However these descriptive words are by no means standard and different regions use different designations.
In the UK and Europe, triage is similar to the USA, but the categories used are dead, those who are pronounced as such by a medically qualified person or paramedic who is legally qualified to pronounce death, the immediate category, who have a trauma score of 3 to 10 (RTS) and need immediate attention, the urgent category, who have a trauma score of 10 or 11 and can wait for a short time before transport to definitive medical attention, and delayed patients, who have a trauma score of 12 (maximum score) and can be delayed before transport from the scene.
A simplified but effective description of the S.T.A.R.T. is taught in the Israeli army to non-medical personnel: the injured who are lying on the ground silently should be prepared for immediate transportation, injured lying on the ground but screaming are injured whose transportation can be delayed, and the walking wounded need help less urgently. A non-medical personnel has no authority to tag an injured person as deceased.
# Simple Triage and Evacuation
Simple triage identifies which persons need advanced medical care.
In the field, triage also sets priorities for evacuation to hospitals.
In START, persons should be evacuated as follows:
- Deceased are left where they fell, covered if necessary; note that in S.T.A.R.T. a person is not triaged "deceased" unless they are not breathing and an effort to reposition their airway has been unsuccessful.
- Immediate or Priority 1 (red) evacuation by MEDEVAC if available or ambulance as they need advanced medical care at once or within 1 hour. These people are in critical condition and would die without immediate assistance.
- Delayed or Priority 2 (yellow) can have their medical evacuation delayed until all immediate persons have been transported. These people are in stable condition but require medical assistance.
- Minor or Priority 3 (green) are not evacuated until all immediate and delayed persons have been evacuated. These will not need advanced medical care for at least several hours. Continue to re-triage in case their condition worsens. These people are able to walk, and may only require bandages and antiseptic.
A popular Triage Tag is the Smart Tag with its unique folded design means that effective triage is quick and simple, but most importantly it allows casualties to be re-triaged without having to replace the tag. It has been adopted as the standard triage tag for New York, Connecticut, Philadelphia, Boston and Nevada.
# Advanced Triage
In advanced triage systems, secondary triage is typically implemented by paramedics, battlefield medical personnel or by skilled nurses in the emergency departments of hospitals during disasters, injured people are sorted into five categories.
If immediate treatment is successful, the patient may improve (although this may be temporary) and this improvement may allow the patient to be categorized to a lower priority in the short term. Triage should be a continuous process and categories should be checked regularly to ensure that the priority remains correct. A trauma score is invariably taken when the victim first comes into hospital and subsequent trauma scores taken to see any changes in the victim's physiological parameters. If a record is provided back in time, the receiving hospital doctor can see a historical trauma score going back in time to the incident. This should allow more definitive treatment to be carried out earlier than might otherwise be the case.
Note that this scale is more complex than simple triage.
Medical professionals should refer to professional texts and training references when implementing advanced triage; this listing is only for a layman's understanding.
Some crippling injuries, even if not life-threatening, may be elevated in priority based on the available capabilities.
During peacetime, most amputations may be triaged "Red" because surgical reattachment must take place within minutes—even though in all probability, the person will not die without a thumb or hand.
# Triage in France
In France, the triage in case of a disaster uses a four-level scale:
- DCD: décédé (deceased), or urgence dépassée (beyond urgency)
- UA: urgence absolue (absolute urgency)
- UR: urgence relative (relative urgency)
- UMP: urgence médico-psychologique (medical-psychological urgency) or impliqué (implied, i.e. lightly wounded or just psychologically shocked).
This triage is performed by a physician called médecin trieur (sorting medic). This triage is usually performed at the field hospital (PMA–poste médical avancé, i.e. forward medical post). The absolute urgencies are usually treated onsite (the PMA has an operating room) or evacuated to a hospital. The relative urgencies are just placed under watch, waiting for an evacuation. The involved are addressed to another structure called the CUMP–Cellule d'urgence médico-psychologique (medical-psychological urgency cell); this is a resting zone, with food and possibly temporary lodging, and a psychologist to take care of the brief reactive psychosis and avoid post-traumatic stress disorder.
In the emergency room of a hospital, the triage is performed by a physician called MAO–médecin d'accueil et d'orientation (reception and orientation physician), and a nurse called IOA– infirmière d'organisation et d'accueil (organisation and reception nurse). Some hospitals and SAMU organisations now use the "Cruciform" card referred to elsewhere.
# Triage in the UK
In the UK, the commonly used triage system is the Smart Incident Command System , taught on MIMMS (Major Incident Medical Management (and) Support). The Military of the United Kingdom|UK Armed Forces are also using this system on operations worldwide. This grades casualties from Priority 1 (most urgent) to Priority 4 (expectant, i.e. likely to die).
Another system is the Cruciform and Manchester triage.
# Triage in Canada
In the mid-1980s, The Victoria General Hospital, in Halifax, Nova Scotia, Canada, introduced paramedic triage in its Emergency Department. Unlike all other centres in North America that employ physician and primarily nurse triage models, this hospital began the practice of employing Primary Care level paramedics to perform triage upon entry to the Emergency Department. In 1997, following the amalgamation of two of the city's largest hospitals, the Emergency Department at the Victoria General closed. The paramedic triage system was moved to the city's only remaining adult emergency department, located at the New Halifax Infirmary. In 2006, a triage protocol on whom to exclude from treatment during a flu pandemic was written by a team of critical-care doctors at the behest of the Ontario government. The protocol was published in the Canadian Medical Association Journal.
# Triage in North Korea
During the food crisis of the early 1990s the People's republic of North Korea adapted a system of triage to allocate aid and food in order to ensure their military and high ranking cadres were allotted ample rations. This often left the population in the urban north in particular to scrounge for food or die.
# Reverse Triage
In addition to the standard practices of triage as mentioned above, there are conditions where sometimes the less wounded are treated in preference to the more severely wounded. This may arise in a situation such as war where the military setting may require soldiers be returned to combat as quickly as possible. Other possible scenarios where this could arise include situations where significant numbers of medical personnel are among the affected patients where it may be advantageous to ensure that they survive to continue providing care in the coming days especially if medical resources are already stretched.
# Alternative Care Facilities
Alternative Care Facilities (ACFs) are places that are setup for the care of large numbers of patients, or are places that could be so set up. Examples include schools, sports stadiums, and large camps that can be prepared and used for the care, feeding, and holding of large numbers of victims of a mass casualty event.
# Related Chapters
- Battlefield medicine
- Combat stress reaction
- First aid
- Mass decontamination
- Wilderness first aid | Triage
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
# Overview
Triage is a system of sorting patients according to need when resources are insufficient for all to be treated. The term comes from the French tri (meaning sort). There are two kinds: simple triage and advanced triage.
# Classification
Simple triage is used in a scene of mass casualty, in order to sort patients into those who need critical attention and immediate transport to the hospital and those with less serious injuries. This step is required before transportation becomes available. The categorization of patients based on the severity of their injuries can be aided with the use of printed triage tags or colored flagging.
In advanced triage, doctors may decide that some seriously injured people should not receive advanced care because they are unlikely to survive. Advanced care will be used on patients with less severe injuries. Because treatment is intentionally withheld from patients with certain injuries, Advanced triage has ethical implications. It is used to divert scarce resources away from patients with little chance of survival in order to increase the chances of survival of others who are more likely to survive.
In Western Europe, the criterion used for this category of patient is a trauma score of consistently at or below 3. This can be determined by using the triage Revised Trauma Score (TRTS), a medically validated scoring system incorporated in some triage cards.
The use of advanced triage may become necessary when medical professionals decide that the medical resources available are not sufficient to treat all the people who need help. This has happened in disasters such as volcanoes, thunderstorms, and rail accidents. In these cases some percentage of patients will die regardless of medical care because of the severity of their injuries. Others would live if given immediate medical care, but would die without it.
In this extreme case, any medical care given to people doomed to die can be considered to be care withdrawn from people who might live if they had been given it. It becomes the task of the disaster medical authorities to put aside some victims, to avoid saving one life at the expense of several others.
Triage is now also applied in system development. Requirements and design options are triaged to avoid wasting effort on ideas that will obviously never succeed.
# Simple Triage and Rapid Treatment
Template:Mainarticle
S.T.A.R.T. (Simple Triage and Rapid Treatment) is a simple triage system that can be performed by lightly-trained lay and emergency personnel in emergencies.
It is not intended to supersede or instruct medical personnel or techniques.
It may serve as an instructive example, and has been (2003) taught to California emergency workers for use in earthquakes. It was developed at Hoag Hospital in Newport Beach, California for use by emergency services It has been field-proven in mass casualty incidents such as train wrecks and bus accidents, though it was developed for use by CERTs and firemen after earthquakes.
Triage separates the injured into four groups: The deceased who are beyond help, the injured who can be helped by immediate transportation, the injured whose transport can be delayed, and those with minor injuries, who need help less urgently. However these descriptive words are by no means standard and different regions use different designations.
In the UK and Europe, triage is similar to the USA, but the categories used are dead, those who are pronounced as such by a medically qualified person or paramedic who is legally qualified to pronounce death, the immediate category, who have a trauma score of 3 to 10 (RTS) and need immediate attention, the urgent category, who have a trauma score of 10 or 11 and can wait for a short time before transport to definitive medical attention, and delayed patients, who have a trauma score of 12 (maximum score) and can be delayed before transport from the scene.
A simplified but effective description of the S.T.A.R.T. is taught in the Israeli army to non-medical personnel: the injured who are lying on the ground silently should be prepared for immediate transportation, injured lying on the ground but screaming are injured whose transportation can be delayed, and the walking wounded need help less urgently. A non-medical personnel has no authority to tag an injured person as deceased.
# Simple Triage and Evacuation
Simple triage identifies which persons need advanced medical care.
In the field, triage also sets priorities for evacuation to hospitals.
In START, persons should be evacuated as follows:
- Deceased are left where they fell, covered if necessary; note that in S.T.A.R.T. a person is not triaged "deceased" unless they are not breathing and an effort to reposition their airway has been unsuccessful.
- Immediate or Priority 1 (red) evacuation by MEDEVAC if available or ambulance as they need advanced medical care at once or within 1 hour. These people are in critical condition and would die without immediate assistance.
- Delayed or Priority 2 (yellow) can have their medical evacuation delayed until all immediate persons have been transported. These people are in stable condition but require medical assistance.
- Minor or Priority 3 (green) are not evacuated until all immediate and delayed persons have been evacuated. These will not need advanced medical care for at least several hours. Continue to re-triage in case their condition worsens. These people are able to walk, and may only require bandages and antiseptic.
A popular Triage Tag is the Smart Tag with its unique folded design means that effective triage is quick and simple, but most importantly it allows casualties to be re-triaged without having to replace the tag. It has been adopted as the standard triage tag for New York, Connecticut, Philadelphia, Boston and Nevada.
# Advanced Triage
In advanced triage systems, secondary triage is typically implemented by paramedics, battlefield medical personnel or by skilled nurses in the emergency departments of hospitals during disasters, injured people are sorted into five categories.
If immediate treatment is successful, the patient may improve (although this may be temporary) and this improvement may allow the patient to be categorized to a lower priority in the short term. Triage should be a continuous process and categories should be checked regularly to ensure that the priority remains correct. A trauma score is invariably taken when the victim first comes into hospital and subsequent trauma scores taken to see any changes in the victim's physiological parameters. If a record is provided back in time, the receiving hospital doctor can see a historical trauma score going back in time to the incident. This should allow more definitive treatment to be carried out earlier than might otherwise be the case.
Note that this scale is more complex than simple triage.
Medical professionals should refer to professional texts and training references when implementing advanced triage; this listing is only for a layman's understanding.
Some crippling injuries, even if not life-threatening, may be elevated in priority based on the available capabilities.
During peacetime, most amputations may be triaged "Red" because surgical reattachment must take place within minutes—even though in all probability, the person will not die without a thumb or hand.
# Triage in France
In France, the triage in case of a disaster uses a four-level scale:
- DCD: décédé (deceased), or urgence dépassée (beyond urgency)
- UA: urgence absolue (absolute urgency)
- UR: urgence relative (relative urgency)
- UMP: urgence médico-psychologique (medical-psychological urgency) or impliqué (implied, i.e. lightly wounded or just psychologically shocked).
This triage is performed by a physician called médecin trieur (sorting medic). This triage is usually performed at the field hospital (PMA–poste médical avancé, i.e. forward medical post). The absolute urgencies are usually treated onsite (the PMA has an operating room) or evacuated to a hospital. The relative urgencies are just placed under watch, waiting for an evacuation. The involved are addressed to another structure called the CUMP–Cellule d'urgence médico-psychologique (medical-psychological urgency cell); this is a resting zone, with food and possibly temporary lodging, and a psychologist to take care of the brief reactive psychosis and avoid post-traumatic stress disorder.
In the emergency room of a hospital, the triage is performed by a physician called MAO–médecin d'accueil et d'orientation (reception and orientation physician), and a nurse called IOA– infirmière d'organisation et d'accueil (organisation and reception nurse). Some hospitals and SAMU organisations now use the "Cruciform" card referred to elsewhere.
# Triage in the UK
In the UK, the commonly used triage system is the Smart Incident Command System , taught on MIMMS (Major Incident Medical Management (and) Support). The Military of the United Kingdom|UK Armed Forces are also using this system on operations worldwide. This grades casualties from Priority 1 (most urgent) to Priority 4 (expectant, i.e. likely to die).
Another system is the Cruciform and Manchester triage.
# Triage in Canada
In the mid-1980s, The Victoria General Hospital, in Halifax, Nova Scotia, Canada, introduced paramedic triage in its Emergency Department. Unlike all other centres in North America that employ physician and primarily nurse triage models, this hospital began the practice of employing Primary Care level paramedics to perform triage upon entry to the Emergency Department. In 1997, following the amalgamation of two of the city's largest hospitals, the Emergency Department at the Victoria General closed. The paramedic triage system was moved to the city's only remaining adult emergency department, located at the New Halifax Infirmary. In 2006, a triage protocol on whom to exclude from treatment during a flu pandemic was written by a team of critical-care doctors at the behest of the Ontario government. The protocol was published in the Canadian Medical Association Journal.[2]
# Triage in North Korea
During the food crisis of the early 1990s the People's republic of North Korea adapted a system of triage to allocate aid and food in order to ensure their military and high ranking cadres were allotted ample rations. This often left the population in the urban north in particular to scrounge for food or die.
# Reverse Triage
In addition to the standard practices of triage as mentioned above, there are conditions where sometimes the less wounded are treated in preference to the more severely wounded. This may arise in a situation such as war where the military setting may require soldiers be returned to combat as quickly as possible. Other possible scenarios where this could arise include situations where significant numbers of medical personnel are among the affected patients where it may be advantageous to ensure that they survive to continue providing care in the coming days especially if medical resources are already stretched.
# Alternative Care Facilities
Alternative Care Facilities (ACFs) are places that are setup for the care of large numbers of patients, or are places that could be so set up. Examples include schools, sports stadiums, and large camps that can be prepared and used for the care, feeding, and holding of large numbers of victims of a mass casualty event.
# Related Chapters
- Battlefield medicine
- Combat stress reaction
- First aid
- Mass decontamination
- Wilderness first aid | https://www.wikidoc.org/index.php/Triage | |
1063bc1b6a81f5d028c36fd9f717d677c9ade696 | wikidoc | TroVax | TroVax
# Overview
TroVax is a cancer immunotherapy product produced by Oxford BioMedica. It is a novel cancer vaccine in clinical development with potential application in most solid tumor types and delivers a novel proprietary tumor-associated antigen, 5T4, using a pox virus vector. 5T4 is broadly distributed throughout a wide range of solid cancers and the presence of the 5T4 antigen is correlated with poor prognosis.
# Indication
All solid tumors where the 5T4 tumor antigen is present. Clinical development is ongoing in renal cell carcinoma, colorectal cancer and prostate cancer, and is planned in breast cancer.
# Technical design
TroVax is a proprietary tumor-associated antigen, 5T4, delivered by the pox virus vector, modified vaccinia virus Ankara (MVA).
# Clinical status
Over 150 patients have now been treated with collectively over 500 doses of TroVax in multiple clinical trials. TroVax has been safe and well-tolerated. There have been no serious adverse events related to the product. TroVax has induced an anti-tumor immune response to the 5T4 tumor antigen in over 95% of evaluable patients. The strongest immune responders have also tended to show the greatest clinical benefit.
Oxford BioMedica began patient recruitment in a Phase III trial in renal cell carcinoma in November 2006. Phase II trials in renal cell carcinoma, colorectal cancer and prostate cancer are ongoing. Further Phase II and Phase III trials in colorectal cancer and other solid tumours are planned. The development strategy is designed to support initial product registration for TroVax in the United States in 2009.
# Completed Trials
## Phase I/II trial
### Colorectal cancer
TroVax was administered as a single agent post chemotherapy to combat Stage IV colorectal cancer. It induced an anti-tumor immune response in 94% of patients while 41% of patients showed periods of disease stabilization. The immune response induced by TroVax correlated with time to disease progression (p < 0.01) and a relationship was determined with survival
## Phase II trials
### Colorectal cancer (two trials)
TroVax was administered alongside first-line chemotherapy to combat Stage IV colorectal cancer. It induced an anti-tumor immune response in all patients while 95% of patients showed disease stabilization and 17% of patients showed complete tumor responses. In the TroVax plus FOLFOX trial, the immune response induced by TroVax correlated with tumour responses (p < 0.02). 25% of patients were alive at an average follow-up time of almost two and a half years..
# Ongoing trials
## Phase II trials
### Colorectal cancer
Trovax is administered as an adjuvant to surgery to combat Stage IV colorectal cancer with operable liver metastases. It induced an anti-tumor immune response in 95% of patients while 56% of patients remained disease-free at a median follow-up of nine months.
### Renal cell carcinoma (four trials)
Trovax is administered alongside interleukin-2 or interferon-alpha to combat advanced or metastatic renal cell carcinoma. It has induced an anti-tumor immune response in 88% of patients while several patients have shown partial tumor responses.
### Prostate cancer
Trovax is administered either as a single agent or in combinations with GM-CSF to combat hormone-refractory prostate cancer. It has mounted an immune response in 85% of patients. Further data will be announced in November 2006.
## Phase III trials
### Renal cell carcinoma
Trovax is administered in combinations with interleukin-2, interferon-alpha, sunitinib to combat advanced or metastatic renal cell carcinoma to 700 patients, with the primary endpoint being the rate of overall survival. There is a Special Protocol Assessment agreement with the FDA that specifies the design, conduct, analysis and endpoints of the trial.
# In Design Trials
## Phase II trails
### Breast Cancer
TroVax will be administered after standard chemotherapy to combat Stage III/IV breast cancer to 120 patients, with the key endpoint being progression-free survival compared to historical controls. The United States clinical trial consortium, Southwest Oncology Group has received FDA clearance to start the trial with sponsorship from the United States National Cancer Institute and is expected to begin by end 2006.
## Phase III Trials
### Colorectal cancer
TroVax will be administered with adjuvant chemotherapy to combat Stage II/III colorectal cancer to approximately 3000 patients, with the primary endpoint of overall and disease-free survival at three years. Clinical trial network, QUASAR, is seeking funds for the proposed trial through appropriate agencies
# Commercialisation Strategy
Oxford BioMedica entered a global development and commercialisation agreement for TroVax in March 2007 with sanofi-aventis. There are many aspects to this agreement including co-funding the ongoing TRIST study and funding all other research, development, regulatory and commercialisation activities.
(Source: Oxford Biomedica, 11/09/2007) | TroVax
# Overview
TroVax is a cancer immunotherapy product produced by Oxford BioMedica. It is a novel cancer vaccine in clinical development with potential application in most solid tumor types and delivers a novel proprietary tumor-associated antigen, 5T4, using a pox virus vector. 5T4 is broadly distributed throughout a wide range of solid cancers and the presence of the 5T4 antigen is correlated with poor prognosis.
# Indication
All solid tumors where the 5T4 tumor antigen is present. Clinical development is ongoing in renal cell carcinoma, colorectal cancer and prostate cancer, and is planned in breast cancer.
# Technical design
TroVax is a proprietary tumor-associated antigen, 5T4, delivered by the pox virus vector, modified vaccinia virus Ankara (MVA).
# Clinical status
Over 150 patients have now been treated with collectively over 500 doses of TroVax in multiple clinical trials. TroVax has been safe and well-tolerated. There have been no serious adverse events related to the product. TroVax has induced an anti-tumor immune response to the 5T4 tumor antigen in over 95% of evaluable patients. The strongest immune responders have also tended to show the greatest clinical benefit.
Oxford BioMedica began patient recruitment in a Phase III trial in renal cell carcinoma in November 2006. Phase II trials in renal cell carcinoma, colorectal cancer and prostate cancer are ongoing. Further Phase II and Phase III trials in colorectal cancer and other solid tumours are planned. The development strategy is designed to support initial product registration for TroVax in the United States in 2009.
# Completed Trials
## Phase I/II trial
### Colorectal cancer
TroVax was administered as a single agent post chemotherapy to combat Stage IV colorectal cancer. It induced an anti-tumor immune response in 94% of patients while 41% of patients showed periods of disease stabilization. The immune response induced by TroVax correlated with time to disease progression (p < 0.01) and a relationship was determined with survival
## Phase II trials
### Colorectal cancer (two trials)
TroVax was administered alongside first-line chemotherapy to combat Stage IV colorectal cancer. It induced an anti-tumor immune response in all patients while 95% of patients showed disease stabilization and 17% of patients showed complete tumor responses. In the TroVax plus FOLFOX trial, the immune response induced by TroVax correlated with tumour responses (p < 0.02). 25% of patients were alive at an average follow-up time of almost two and a half years..
# Ongoing trials
## Phase II trials
### Colorectal cancer
Trovax is administered as an adjuvant to surgery to combat Stage IV colorectal cancer with operable liver metastases. It induced an anti-tumor immune response in 95% of patients while 56% of patients remained disease-free at a median follow-up of nine months.
### Renal cell carcinoma (four trials)
Trovax is administered alongside interleukin-2 or interferon-alpha to combat advanced or metastatic renal cell carcinoma. It has induced an anti-tumor immune response in 88% of patients while several patients have shown partial tumor responses.
### Prostate cancer
Trovax is administered either as a single agent or in combinations with GM-CSF to combat hormone-refractory prostate cancer. It has mounted an immune response in 85% of patients. Further data will be announced in November 2006.
## Phase III trials
### Renal cell carcinoma
Trovax is administered in combinations with interleukin-2, interferon-alpha, sunitinib to combat advanced or metastatic renal cell carcinoma to 700 patients, with the primary endpoint being the rate of overall survival. There is a Special Protocol Assessment agreement with the FDA that specifies the design, conduct, analysis and endpoints of the trial.
# In Design Trials
## Phase II trails
### Breast Cancer
TroVax will be administered after standard chemotherapy to combat Stage III/IV breast cancer to 120 patients, with the key endpoint being progression-free survival compared to historical controls. The United States clinical trial consortium, Southwest Oncology Group has received FDA clearance to start the trial with sponsorship from the United States National Cancer Institute and is expected to begin by end 2006.
## Phase III Trials
### Colorectal cancer
TroVax will be administered with adjuvant chemotherapy to combat Stage II/III colorectal cancer to approximately 3000 patients, with the primary endpoint of overall and disease-free survival at three years. Clinical trial network, QUASAR, is seeking funds for the proposed trial through appropriate agencies
# Commercialisation Strategy
Oxford BioMedica entered a global development and commercialisation agreement for TroVax in March 2007 with sanofi-aventis. There are many aspects to this agreement including co-funding the ongoing TRIST study and funding all other research, development, regulatory and commercialisation activities.
(Source: Oxford Biomedica, 11/09/2007)
# External links
- TroVax
- Vaccine for kidney and bowel cancers tested
Template:WH
Template:WS | https://www.wikidoc.org/index.php/TroVax | |
c94e9685c7e79d6c27b7d8e75dff08e3e846897b | wikidoc | Trocar | Trocar
A trocar (Fr. "three side") is a hollow cylinder with a sharply pointed end, often three-sided, that is used to introduce cannulas and other similar implements into blood vessels or body cavities. Trocars are also used as ports in laparoscopic surgery.
The trocar is often passed inside a cannula, and functions as a portal for the subsequent placement of other devices, such as a chest drain, intravenous cannula etc.
Surgical trocars are used to perform laparoscopic ('keyhole') surgery. They are used as a means of introduction for laparoscopic hand instruments, such as scissors, graspers etc., to perform surgery hitherto carried out by making a large abdominal incision ('open' surgery), something that has revolutionized patient care. Surgical trocars are today most commonly a single patient use instrument and have graduated from the 'three point' design that gave them their name, to either a flat bladed 'dilating-tip' product, or something that is entirely blade free. This latter design offers greater patient safety due to the technique used to insert them.
Trocars are also used near the end of the embalming process to provide drainage of bodily fluids and organs after the vascular replacement of blood with embalming chemicals. It is attached to a suction hose (which usually is attached to a running water source and drain known as a hydroaspirator). The process of removing organs using the trocar is known as aspiration. The instrument is inserted into the body two inches above and two inches to the right of the belly button from the embalmer's perspective. After the thoracic, abdominal, and pelvic cavities have been aspirated, the end of the trocar's hose is detached from the hydroaspirator and attached to a bottle of high index cavity fluid. The bottle is held upside down in the air so as to let gravity take the embalming fluid through the trocar and into the cavities. The embalmer moves the trocar in the same manner that he or she used when aspirating the cavities in order to fully and evenly distribute the chemical.
After cavity embalming has been finished, the puncture is commonly sealed using a small, plastic object resembling a screw and called a trocar button. | Trocar
A trocar (Fr. "three side") is a hollow cylinder with a sharply pointed end, often three-sided, that is used to introduce cannulas and other similar implements into blood vessels or body cavities. Trocars are also used as ports in laparoscopic surgery.
The trocar is often passed inside a cannula, and functions as a portal for the subsequent placement of other devices, such as a chest drain, intravenous cannula etc.
Surgical trocars are used to perform laparoscopic ('keyhole') surgery. They are used as a means of introduction for laparoscopic hand instruments, such as scissors, graspers etc., to perform surgery hitherto carried out by making a large abdominal incision ('open' surgery), something that has revolutionized patient care. Surgical trocars are today most commonly a single patient use instrument and have graduated from the 'three point' design that gave them their name, to either a flat bladed 'dilating-tip' product, or something that is entirely blade free. This latter design offers greater patient safety due to the technique used to insert them.
Trocars are also used near the end of the embalming process to provide drainage of bodily fluids and organs after the vascular replacement of blood with embalming chemicals. It is attached to a suction hose (which usually is attached to a running water source and drain known as a hydroaspirator). The process of removing organs using the trocar is known as aspiration. The instrument is inserted into the body two inches above and two inches to the right of the belly button from the embalmer's perspective. After the thoracic, abdominal, and pelvic cavities have been aspirated, the end of the trocar's hose is detached from the hydroaspirator and attached to a bottle of high index cavity fluid. The bottle is held upside down in the air so as to let gravity take the embalming fluid through the trocar and into the cavities. The embalmer moves the trocar in the same manner that he or she used when aspirating the cavities in order to fully and evenly distribute the chemical.
After cavity embalming has been finished, the puncture is commonly sealed using a small, plastic object resembling a screw and called a trocar button. | https://www.wikidoc.org/index.php/Trocar | |
82c92a509f6918f2c2f1224315213e3d0af8a3b2 | wikidoc | Tubers | Tubers
Tubers are various types of modified plant structures that are enlarged to store nutrients. They are used by plants to overwinter and regrow the next year and as a means of asexual reproduction. Two different groups of tubers are: stem tubers, and root tubers.
# Stem tubers
A Stem tuber forms from thickened rhizomes or stolons. The tops or sides of the tuber produce shoots that grow into typical stems and leaves and the under sides produce roots. They tend to form at the sides of the parent plant and are most often located near the soil surface. The below-ground stem tuber is normally a short-lived storage and regenerative organ developing from a shoot that branches off a mature plant. The offspring or new tubers, are attached to a parent tuber or form at the end of a hypogeogenous rhizome. In the fall the plant dies except for the new offspring stem tubers which have one dominant bud, which in spring regrows a new shoot producing stems and leaves, in summer the tubers decay and new tubers begin to grow. Some plants also form smaller tubers and/or tubercules which act like seeds, producing small plants that resemble in morphology and size seedlings. Some stem tubers are long lived such as those of tuberous begonia but many tuberous plants have tubers that survive only until the plants have fully leafed out, at which point the tuber is reduced to a shriveled up husk.
Stem tubers generally start off as enlargements of the hypococtyl section of a seedling but also sometimes include the first node or two of the epicotyl and the upper section of the root. The stem tuber has a vertical orientation with one or a few vegetative buds on the top and fibrous roots produced on the bottom from a basal section, typically the stem tuber has an oblong rounded shape.
Tuberous begonia and Cyclamen are commonly grown stem tubers.
Mignonette vine (Anredera cordifolia) produces aerial stem tubers on 12 to 25 foot tall vines, the tubers fall to the ground and grow. Plectranthus esculentus of the mint family Lamiaceae, produces tuberous under ground organs from the base of the stem, weighing up to 1.8 kg per tuber, forming from axillary buds producing short stolons that grow into tubers.
## Potatoes
Potato tubers are the development of enlarged stolons thickened into storage organs, they are specialized swollen stems.
The tuber has all the parts of a normal stem, including nodes and internodes, the nodes are the eyes and each have a leaf scar. The nodes or eyes are arranged around the tuber in a spiral fashion beginning on the end opposite the attachment point to the stolon. The terminal bud is produced at the farthest point away from the stolon attachment and tuber thus shows the same apical dominance of a normal stem. Internally a tuber is filled with starch stored in enlarged parenchyma like cells; also internally the tuber has the typical cell structures of any stem, including a pith, vascular zones and a cortex.
The tuber is produced in one growing season and used to perennialize the plant and as a means of propagation. When fall comes the above ground structure of the plant dies and the tubers over winter under ground until spring, when they regenerate new shoots which use the stored food in the tuber to grow. As the main shoot develops from the tuber, the base of the shoot close to the tuber produces adventitious roots and lateral buds on the shoot, The shoot also produce stolons that are long etiolated stems. The stolon elongates during long days with the presence of auxins and high gibberellin levels that prevent root growth off of the stolon. Before new tuber formation begins the stolon must be a certain age. The hormone lipoxygenase is involved in the control of potato tuber development.
The stolons are easily recognized when potato plants are grown from seed, as the plants grow, stolons are produced around the soil surface from the nodes. The tubers form close to the soil surface and sometimes even on top of the ground. When potatoes are cultivated, the tubers are cut into pieces and planted much deeper into the soil. By planting the pieces deeper there is more area for the plants to generate the tubers and their size increases. The pieces sprout shoots that grow to the surface, these shoots are rhizome like and generate short stolons from the nodes while in the ground. When the shoots reach the soil surface they produce roots and shoots that grow into the green plant.
Stem tubers should not be confused with tuberous roots, sometimes called root tubers, such as a sweet potato or Dahlia.
See also:
- Bulb - modified stem tubers with a short fleshy vertical stem, covered by thick fleshy modified leaves.
- corm - modified stems covered by dry scale-like leaves called a tunic, differing from true bulbs by having distinct nodes and internodes.
# Root tubers
A tuberous root is a modified lateral root, enlarged to function as a storage organ. It is thus different in origin but similar in function and appearance to a tuber. Examples of plants with notable root tubers include the sweet potato, cassava and Dahlia.
It is a structure used to perennialize the plant for survival from one year to the next.
The thickened roots are storage organs that differ from true tubers. The massive enlargement of secondary roots typically represented by Sweet Potato (Ipomoea batatas), have the internal and external cell structures of typical roots. True tubers have the cell structure of stems, In root tubers there are no nodes and internodes or reduced leaves. One end called the proximal end has crown tissue that produces buds that grow into stems and foliage. The other end called the distal end normally produces unmodified roots. In true tubers the order is reversed with the distal end producing stems. Tuberous roots are biennial in duration, the first year the parent plant produces the root tubers and in the fall the plant dies. The next year the root tubers produce a new plant and are consumed in the production of new roots and stems and flowering. The remaining tissue dies while the plants generates new root tubers for the next year.
Hemerocallis fulva plus a number of Daylily hybrids have large root tubers, H. fulva spreads by underground stolons that end with a new fan that grows roots that produce thick root tubers and then send our more stolons.
Plants with root tubers are propagated in late summer to late winter by digging up the tubers and separating them, making sure that each piece has some crown tissue and replanting. | Tubers
Template:Distinguish2
Tubers are various types of modified plant structures that are enlarged to store nutrients. They are used by plants to overwinter and regrow the next year and as a means of asexual reproduction. Two different groups of tubers are: stem tubers, and root tubers.
# Stem tubers
A Stem tuber forms from thickened rhizomes or stolons. The tops or sides of the tuber produce shoots that grow into typical stems and leaves and the under sides produce roots. They tend to form at the sides of the parent plant and are most often located near the soil surface. The below-ground stem tuber is normally a short-lived storage and regenerative organ developing from a shoot that branches off a mature plant. The offspring or new tubers, are attached to a parent tuber or form at the end of a hypogeogenous rhizome. In the fall the plant dies except for the new offspring stem tubers which have one dominant bud, which in spring regrows a new shoot producing stems and leaves, in summer the tubers decay and new tubers begin to grow. Some plants also form smaller tubers and/or tubercules which act like seeds, producing small plants that resemble in morphology and size seedlings. Some stem tubers are long lived such as those of tuberous begonia but many tuberous plants have tubers that survive only until the plants have fully leafed out, at which point the tuber is reduced to a shriveled up husk.
Stem tubers generally start off as enlargements of the hypococtyl section of a seedling but also sometimes include the first node or two of the epicotyl and the upper section of the root. The stem tuber has a vertical orientation with one or a few vegetative buds on the top and fibrous roots produced on the bottom from a basal section, typically the stem tuber has an oblong rounded shape.
Tuberous begonia and Cyclamen are commonly grown stem tubers.
Mignonette vine (Anredera cordifolia) produces aerial stem tubers on 12 to 25 foot tall vines, the tubers fall to the ground and grow. Plectranthus esculentus of the mint family Lamiaceae, produces tuberous under ground organs from the base of the stem, weighing up to 1.8 kg per tuber, forming from axillary buds producing short stolons that grow into tubers.[1]
## Potatoes
Potato tubers are the development of enlarged stolons thickened into storage organs, they are specialized swollen stems.[2]
[3][4]
The tuber has all the parts of a normal stem, including nodes and internodes, the nodes are the eyes and each have a leaf scar. The nodes or eyes are arranged around the tuber in a spiral fashion beginning on the end opposite the attachment point to the stolon. The terminal bud is produced at the farthest point away from the stolon attachment and tuber thus shows the same apical dominance of a normal stem. Internally a tuber is filled with starch stored in enlarged parenchyma like cells; also internally the tuber has the typical cell structures of any stem, including a pith, vascular zones and a cortex.
The tuber is produced in one growing season and used to perennialize the plant and as a means of propagation. When fall comes the above ground structure of the plant dies and the tubers over winter under ground until spring, when they regenerate new shoots which use the stored food in the tuber to grow. As the main shoot develops from the tuber, the base of the shoot close to the tuber produces adventitious roots and lateral buds on the shoot, The shoot also produce stolons that are long etiolated stems. The stolon elongates during long days with the presence of auxins and high gibberellin levels that prevent root growth off of the stolon. Before new tuber formation begins the stolon must be a certain age. The hormone lipoxygenase is involved in the control of potato tuber development.
The stolons are easily recognized when potato plants are grown from seed, as the plants grow, stolons are produced around the soil surface from the nodes. The tubers form close to the soil surface and sometimes even on top of the ground. When potatoes are cultivated, the tubers are cut into pieces and planted much deeper into the soil. By planting the pieces deeper there is more area for the plants to generate the tubers and their size increases. The pieces sprout shoots that grow to the surface, these shoots are rhizome like and generate short stolons from the nodes while in the ground. When the shoots reach the soil surface they produce roots and shoots that grow into the green plant.
Stem tubers should not be confused with tuberous roots, sometimes called root tubers, such as a sweet potato or Dahlia.
See also:
- Bulb - modified stem tubers with a short fleshy vertical stem, covered by thick fleshy modified leaves.
- corm - modified stems covered by dry scale-like leaves called a tunic, differing from true bulbs by having distinct nodes and internodes.
# Root tubers
A tuberous root is a modified lateral root, enlarged to function as a storage organ. It is thus different in origin but similar in function and appearance to a tuber. Examples of plants with notable root tubers include the sweet potato, cassava and Dahlia.
It is a structure used to perennialize the plant for survival from one year to the next.
The thickened roots are storage organs that differ from true tubers. The massive enlargement of secondary roots typically represented by Sweet Potato (Ipomoea batatas), have the internal and external cell structures of typical roots. True tubers have the cell structure of stems, In root tubers there are no nodes and internodes or reduced leaves. One end called the proximal end has crown tissue that produces buds that grow into stems and foliage. The other end called the distal end normally produces unmodified roots. In true tubers the order is reversed with the distal end producing stems. Tuberous roots are biennial in duration, the first year the parent plant produces the root tubers and in the fall the plant dies. The next year the root tubers produce a new plant and are consumed in the production of new roots and stems and flowering. The remaining tissue dies while the plants generates new root tubers for the next year.
Hemerocallis fulva plus a number of Daylily hybrids have large root tubers, H. fulva spreads by underground stolons that end with a new fan that grows roots that produce thick root tubers and then send our more stolons.
Plants with root tubers are propagated in late summer to late winter by digging up the tubers and separating them, making sure that each piece has some crown tissue and replanting. | https://www.wikidoc.org/index.php/Tubers | |
16ffdcf294e01247ab708d3a14cd0612bc7bb403 | wikidoc | Tuinal | Tuinal
Tuinal is the brand name of a combination drug composed of two barbiturate salts (secobarbital sodium and amobarbital sodium) in equal proportions.
Tuinal was introduced as a sedative medication in the late 1940s by Eli Lilly. It was produced in gelatin capsule form for oral administration. Individual capsules contained 50mg, 100mg, or 200mg of barbiturate salts.
Eli Lilly has discontinued the manufacture of Tuinal in the United States due to the diminishing use of barbiturates in outpatient treatment. Currently Ranbaxy Pharmaceuticals is the sole producer of this barbiturate formulation. In the United Kingdom, Tuinal, Seconal and Sodium Amytal are manufactured by Flynn Pharma of Ireland. Amytal has been discontinued, though Sodium Amytal remains.
# Abuse
Tuinal (or Tuinol as it is sometimes colloquially misspelled) saw widespread use as a recreational drug in the 1960s and 1970s. The pill was known colloquially under the street name "Christmas trees," a reference to the unique color scheme of the capsule. Like other barbiturate depressants, Tuinal promotes physical and psychological dependency and carries a high risk of overdose. Abuse of this particular drug tapered off after it was withdrawn from the market.
Tuinal is classified as a Schedule II drug under the Controlled Substances Act in the United States.
# Trivia
In a scene from the Stephen King novel Pet Sematary, the main character, Dr. Louis Creed, swallows a Tuinal to calm himself down. Creed then recalls a friend from medical school with a particular fondness for Tuinal, which the friend dubbed "the Toonerville trolley," or "tooners" for short.
In "The Old Main Drag", a song from The Pogues' 1985 album Rum, Sodomy, and the Lash, the drug is name-checked: If you didn't have the money, you'd cajole and you'd beg / There was always lots of Tuinal on the old main drag.
In the Hawkwind song "Lost Johnny", the drug appears in the verse "We're all taking Tuinal to murder our young dreams." Later, when Motörhead performed the song, the verse became "We're all shooting Tuinal to murder all your dreams."
In John Betjeman's poem "Shattered Image" (1970), an accused child molestor wonders how many of his Tuinal - used, presumably, as a recreational depressant - it will take to kill himself.
In Grace Paley's poem "On the Fourth Floor" a boy screams to his girl that of sixteen Tuinal, he cannot account for two.
In Andrew Holleran's novel Dancer from the Dance (1978) a case of overdose in a discotheque is mentioned: "The boy passed out on the sofa from an overdose of Tuinols was a Puerto Rican who washed dishes in the employees' cafeteria at CBS, but the doctor bending over him had treated presidents." (40)
In The Ramones song Psycho Therapy, Joey Ramone sings in the second verse "I like taking Tuinal / It keeps me edgy and mean / I'm a teenage schizoid / I'm a teenage dope fiend".
The Queers song Feeling So Groovy has the verse "I'm really not that dumb you know / got lots of beer and Tuinals".
In the movie Fight Club, Jacks' narration refers to "red and blue Tuinals" when he sees the doctor about his insomnia.
In the Lou Reed song "New Sensations" he sings "It's easy enough to tell what is wrong, but that's not what I want to hear all night long, some people are like human Tuinals."
Irish singer Shane McGowan references the drug in "The Old Main Drag" from The Pogues' "Rum, Sodomy & The Lash" album. The song, about McGowan's time as runaway on the streets of London, contains the lines "In the cold winter nights the old town it was chill / But there were boys in the cafes who'd give you cheap pills / If you didn't have the money you'd cajole and you'd beg / There was always lots of Tuinal on the old main drag"
American writer/poet/singer Jim Carroll is reputed to be the voice heard asking an anonymous patron about the availability of Tuinals between songs on The Velvet Underground's "Live At Max's Kansas City" album. | Tuinal
Tuinal is the brand name of a combination drug composed of two barbiturate salts (secobarbital sodium and amobarbital sodium) in equal proportions.
Tuinal was introduced as a sedative medication in the late 1940s by Eli Lilly. It was produced in gelatin capsule form for oral administration. Individual capsules contained 50mg, 100mg, or 200mg of barbiturate salts.
Eli Lilly has discontinued the manufacture of Tuinal in the United States due to the diminishing use of barbiturates in outpatient treatment. Currently Ranbaxy Pharmaceuticals is the sole producer of this barbiturate formulation. In the United Kingdom, Tuinal, Seconal and Sodium Amytal are manufactured by Flynn Pharma of Ireland. Amytal has been discontinued, though Sodium Amytal remains.
# Abuse
Tuinal (or Tuinol as it is sometimes colloquially misspelled) saw widespread use as a recreational drug in the 1960s and 1970s. The pill was known colloquially under the street name "Christmas trees," a reference to the unique color scheme of the capsule. Like other barbiturate depressants, Tuinal promotes physical and psychological dependency and carries a high risk of overdose. Abuse of this particular drug tapered off after it was withdrawn from the market.
Tuinal is classified as a Schedule II drug under the Controlled Substances Act in the United States.
# Trivia
In a scene from the Stephen King novel Pet Sematary, the main character, Dr. Louis Creed, swallows a Tuinal to calm himself down. Creed then recalls a friend from medical school with a particular fondness for Tuinal, which the friend dubbed "the Toonerville trolley," or "tooners" for short.
In "The Old Main Drag", a song from The Pogues' 1985 album Rum, Sodomy, and the Lash, the drug is name-checked: If you didn't have the money, you'd cajole and you'd beg / There was always lots of Tuinal on the old main drag.
In the Hawkwind song "Lost Johnny", the drug appears in the verse "We're all taking Tuinal to murder our young dreams." Later, when Motörhead performed the song, the verse became "We're all shooting Tuinal to murder all your dreams."
In John Betjeman's poem "Shattered Image" (1970), an accused child molestor wonders how many of his Tuinal - used, presumably, as a recreational depressant - it will take to kill himself.
In Grace Paley's poem "On the Fourth Floor" a boy screams to his girl that of sixteen Tuinal, he cannot account for two.
In Andrew Holleran's novel Dancer from the Dance (1978) a case of overdose in a discotheque is mentioned: "The boy passed out on the sofa from an overdose of Tuinols [sic] was a Puerto Rican who washed dishes in the employees' cafeteria at CBS, but the doctor bending over him had treated presidents." (40)
In The Ramones song Psycho Therapy, Joey Ramone sings in the second verse "I like taking Tuinal / It keeps me edgy and mean / I'm a teenage schizoid / I'm a teenage dope fiend".
The Queers song Feeling So Groovy has the verse "I'm really not that dumb you know / got lots of beer and Tuinals".
In the movie Fight Club, Jacks' narration refers to "red and blue Tuinals" when he sees the doctor about his insomnia.
In the Lou Reed song "New Sensations" he sings "It's easy enough to tell what is wrong, but that's not what I want to hear all night long, some people are like human Tuinals."
Irish singer Shane McGowan references the drug in "The Old Main Drag" from The Pogues' "Rum, Sodomy & The Lash" album. The song, about McGowan's time as runaway on the streets of London, contains the lines "In the cold winter nights the old town it was chill / But there were boys in the cafes who'd give you cheap pills / If you didn't have the money you'd cajole and you'd beg / There was always lots of Tuinal on the old main drag"
American writer/poet/singer Jim Carroll is reputed to be the voice heard asking an anonymous patron about the availability of Tuinals between songs on The Velvet Underground's "Live At Max's Kansas City" album. | https://www.wikidoc.org/index.php/Tuinal | |
cbbd83fef13dcb9329bc84d6103411a6c570f11e | wikidoc | Twitch | Twitch
Twitch may refer to:
- Muscle twitch, a muscle contraction
Fasciculation, a small, local, involuntary muscle contraction
Myoclonic twitch, a jerk usually caused by sudden muscle contractions
Spasm, a sudden, involuntary contraction of a muscle, group of muscles, hollow organ, or orifice
Tic, a sudden, repetitive, nonrhythmic movement or sound that involves discrete groups of muscles
- Fasciculation, a small, local, involuntary muscle contraction
- Myoclonic twitch, a jerk usually caused by sudden muscle contractions
- Spasm, a sudden, involuntary contraction of a muscle, group of muscles, hollow organ, or orifice
- Tic, a sudden, repetitive, nonrhythmic movement or sound that involves discrete groups of muscles
In entertainment:
- Twitch (film), a short film directed by Leah Meyerhoff
- Twitch (album), by Ministry
- Twitch (Aldo Nova album)
- Twitch (EP), by Jebediah
- Max "Twitch" Williams, a police officer in the comic series Sam and Twitch, a spinoff of Spawn
In other uses:
- Twitch (device), a device used to restrain horses
- "Twitch", in birdwatching, to pursue and observe a rare bird | Twitch
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Template:Wiktionarypar
Twitch may refer to:
- Muscle twitch, a muscle contraction
Fasciculation, a small, local, involuntary muscle contraction
Myoclonic twitch, a jerk usually caused by sudden muscle contractions
Spasm, a sudden, involuntary contraction of a muscle, group of muscles, hollow organ, or orifice
Tic, a sudden, repetitive, nonrhythmic movement or sound that involves discrete groups of muscles
- Fasciculation, a small, local, involuntary muscle contraction
- Myoclonic twitch, a jerk usually caused by sudden muscle contractions
- Spasm, a sudden, involuntary contraction of a muscle, group of muscles, hollow organ, or orifice
- Tic, a sudden, repetitive, nonrhythmic movement or sound that involves discrete groups of muscles
In entertainment:
- Twitch (film), a short film directed by Leah Meyerhoff
- Twitch (album), by Ministry
- Twitch (Aldo Nova album)
- Twitch (EP), by Jebediah
- Max "Twitch" Williams, a police officer in the comic series Sam and Twitch, a spinoff of Spawn
In other uses:
- Twitch (device), a device used to restrain horses
- "Twitch", in birdwatching, to pursue and observe a rare bird | https://www.wikidoc.org/index.php/Twitch | |
b504ee7e71f60158ee5a635a0770a9170bb6330f | wikidoc | UBE2E1 | UBE2E1
Ubiquitin-conjugating enzyme E2 E1 is a protein that in humans is encoded by the UBE2E1 gene.
# Function
The modification of proteins with ubiquitin is an important cellular mechanism for targeting abnormal or short-lived proteins for degradation. Ubiquitination involves at least three classes of enzymes: ubiquitin-activating enzymes, or E1s, ubiquitin-conjugating enzymes, or E2s, and ubiquitin-protein ligases, or E3s. This gene encodes a member of the E2 ubiquitin-conjugating enzyme family. Two alternatively spliced transcript variants encoding distinct isoforms have been found for this gene.
# Interactions
UBE2E1 has been shown to interact with Ataxin 1 and NEDD4. | UBE2E1
Ubiquitin-conjugating enzyme E2 E1 is a protein that in humans is encoded by the UBE2E1 gene.[1][2]
# Function
The modification of proteins with ubiquitin is an important cellular mechanism for targeting abnormal or short-lived proteins for degradation. Ubiquitination involves at least three classes of enzymes: ubiquitin-activating enzymes, or E1s, ubiquitin-conjugating enzymes, or E2s, and ubiquitin-protein ligases, or E3s. This gene encodes a member of the E2 ubiquitin-conjugating enzyme family. Two alternatively spliced transcript variants encoding distinct isoforms have been found for this gene.[2]
# Interactions
UBE2E1 has been shown to interact with Ataxin 1[3] and NEDD4.[4][5] | https://www.wikidoc.org/index.php/UBE2E1 | |
14b4bf8eac0d1682de319b1c33b4e0d632825f08 | wikidoc | UBE2L3 | UBE2L3
Ubiquitin-conjugating enzyme E2 L3 (UBE2L3), also called UBCH7, is a protein that in humans is encoded by the UBE2L3 gene. As an E2 enzyme, UBE2L3 participates in ubiquitination to target proteins for degradation. The role of UBE2L3 in the ubiquitination of the NF-κB precursor implicated it in various major autoimmune diseases, including rheumatoid arthritis (RA), celiac disease, Crohn's disease(CD), and systemic lupus erythematosus.
# Structure
## Gene
The UBE2L3 gene is located at chromosome 22q11.21, consisting of 6 exons.Two alternatively spliced transcript variants encoding distinct isoforms have been found for this gene.
## Protein
There are 38 E2 enzymes in humans. They all contain a conserved catalytic core domain that interacts with E1 and E3 and many E2s possess additional N- and/or C-terminal protein sequences. In contrast to other E2s, residues necessary for lysine reactivity are absent: the D87 and D117 residues (in UBCH5C numbering) are replaced by Pro and His residues.
# Function
The modification of proteins with ubiquitin is an important cellular mechanism for targeting abnormal or short-lived proteins for degradation. Ubiquitination involves at least three classes of enzymes: ubiquitin-activating enzymes (E1s), ubiquitin-conjugating enzymes (E2s) and ubiquitin-protein ligases (E3s). E2s play a key role in the whole ubiquitin (Ub) transfer pathway and are responsible for Ub cellular signaling. Unlike many E2s that transfer Ub with RINGs, UBE2L3 has E3-independent reactivity with lysine. This enzyme is demonstrated to participate in the ubiquitination of p53, c-Fos, and the NF-κB precursor p105 in vitro. UBE2L3 is primarily known for its role in the cell cycle. Specifically, UBE2L3 manages cell cycle regulatory protein levels via the ubiquitin proteolytic pathway (UPP) during the G1/S transition and during the actual S phase.
# Clinical significance
Through genome-wide association studies (GWAS), UBE2L3 has been associated with several autoimmune diseases, including RA, celiac disease, CD, and SLE via the ubiquitination of the NK-κB precursor.
# Interactions
UBE2L3 has been shown to interact with:
- ARIH1,
- ARIH2,
- CBL,
- CHEK1,
- NEDD4,
- PARK2,
- SMURF2,
- TNFAIP3,
- TNFSF4,
- TNIP1,
- TRAF6,
- UBE3A,
- UBE3A, and
- UBOX5. | UBE2L3
Ubiquitin-conjugating enzyme E2 L3 (UBE2L3), also called UBCH7, is a protein that in humans is encoded by the UBE2L3 gene.[1][2][3] As an E2 enzyme, UBE2L3 participates in ubiquitination to target proteins for degradation.[3] The role of UBE2L3 in the ubiquitination of the NF-κB precursor implicated it in various major autoimmune diseases, including rheumatoid arthritis (RA), celiac disease, Crohn's disease(CD), and systemic lupus erythematosus.[4]
# Structure
## Gene
The UBE2L3 gene is located at chromosome 22q11.21, consisting of 6 exons.Two alternatively spliced transcript variants encoding distinct isoforms have been found for this gene.[3]
## Protein
There are 38 E2 enzymes in humans.[5] They all contain a conserved catalytic core domain that interacts with E1 and E3 and many E2s possess additional N- and/or C-terminal protein sequences.[6][7] In contrast to other E2s, residues necessary for lysine reactivity are absent: the D87 and D117 residues (in UBCH5C numbering) are replaced by Pro and His residues.[8]
# Function
The modification of proteins with ubiquitin is an important cellular mechanism for targeting abnormal or short-lived proteins for degradation. Ubiquitination involves at least three classes of enzymes: ubiquitin-activating enzymes (E1s), ubiquitin-conjugating enzymes (E2s) and ubiquitin-protein ligases (E3s). E2s play a key role in the whole ubiquitin (Ub) transfer pathway and are responsible for Ub cellular signaling. Unlike many E2s that transfer Ub with RINGs, UBE2L3 has E3-independent reactivity with lysine.[8] This enzyme is demonstrated to participate in the ubiquitination of p53, c-Fos, and the NF-κB precursor p105 in vitro. UBE2L3 is primarily known for its role in the cell cycle. Specifically, UBE2L3 manages cell cycle regulatory protein levels via the ubiquitin proteolytic pathway (UPP) during the G1/S transition and during the actual S phase.[9]
# Clinical significance
Through genome-wide association studies (GWAS), UBE2L3 has been associated with several autoimmune diseases, including RA, celiac disease, CD, and SLE via the ubiquitination of the NK-κB precursor.[9][10][11] This association was observed in European, Asian, and African-American populations.[9] UBE2L3 has been linked to natural killer cell cytotoxic function, and high UBE2L3 levels had contributed to clearing chronic HBV infection.[4][11] UBE2L3 controls the protein stability of 53BP1 and determines the DNA double-strand break repair choice. Loss of UBE2L3 stabilizes 53BP1 and force cells to choose NHEJ to repair DNA double-strand break. Repair by NHEJ leads to radial chromosomes and cell death.[12][13] UBE2L3 depletion may become a novel strategy in enhancing the effect of anticancer therapies.[14] The haplotype of UBE2L3 gene is also reported associated with Hashimoto's thyroiditis in a Chinese Han population.[15](27094594)
# Interactions
UBE2L3 has been shown to interact with:
- ARIH1,[16][17][18]
- ARIH2,[19]
- CBL,[20][21][22]
- CHEK1,[19]
- NEDD4,[23][24]
- PARK2,[19]
- SMURF2,[19]
- TNFAIP3,[10]
- TNFSF4,[10]
- TNIP1,[10]
- TRAF6,[19]
- UBE3A,[19]
- UBE3A,[23][25][26] and
- UBOX5.[27] | https://www.wikidoc.org/index.php/UBE2L3 | |
216d8bcdf94886a45cb339710eef877a55150db7 | wikidoc | UBE2V2 | UBE2V2
Ubiquitin-conjugating enzyme E2 variant 2 is a protein that in humans is encoded by the UBE2V2 gene. Ubiquitin-conjugating enzyme E2 variant proteins constitute a distinct subfamily within the E2 protein family.
# Structure
UBE2V2 has sequence similarity to other ubiquitin-conjugating enzymes but lack the conserved cysteine residue that is critical for the catalytic activity of E2s. The protein encoded by this gene also shares homology with ubiquitin-conjugating enzyme E2 variant 1 and yeast MMS2 gene product.
# Function
UBE2V2 has also been implicated as an intracellular sensor of reactive electrophilic species, which are present in high levels during periods of pathogenic and/or environmental stress. The C69 residue of UBE2V2 is capable of binding with various RES. It has been shown that binding of RES to UBE2V2 promotes UBE2V2-mediated activation of Ube2N, another E2 protein that complexes with UBE2V2. Activated Ube2N has been shown to play a major role in promoting DNA-damage responses. Thus, UBE2V2 may promote genome integrity by directly sensing RES and effecting DNA damage responses. It may also be involved in the differentiation of monocytes and enterocytes.
# Interactions
UBE2V2 has been shown to interact with HLTF. Although UBE2V2 itself lacks ubiquitin-conjugating activity, it can interact with different Ubiquitin-conjugating enzymes to facilitate their catalytic activities. For instance, UBE2V2 can complex with UBE2N to form a heterodimer capable of synthesizing Lys-63 linked polyubiquitin chains. UBE2V2 may facilitate UBE2N activity by coordinating UBE2N's positioning to promote ubiquitin chain formation specifically at Lys-63, as the ubiquitin molecule has multiple potential Lysine binding sites. Similarly, it has been shown that UBE2V2 interact with the ubiquitin-conjugating enzyme, Ubc13, to induce Ubc13 to adopt an active conformation that can create Lys-63 polyubituitin chains on various substrates.
Addition of Lys-63 polyubiquitin chains to intracellular targets is distinct from the canonical Lys-48 polyubiquitin chains in that Lys-63 chains do not mediate proteasomal degradation of its substrate. Although their function remains poorly characterized, Lys-63 chains have been shown to regulate signaling pathways by either activating or inhibiting its target protein function. For example, TRIM5alpha restriction of retroviral reverse-transcription is dependent on UBE2V2/UBE2N-mediated poly-ubiquitination. UBE2V2 has been shown to regulate TRIM21 antiviral activity in an analogous manner. | UBE2V2
Ubiquitin-conjugating enzyme E2 variant 2 is a protein that in humans is encoded by the UBE2V2 gene.[1][2] Ubiquitin-conjugating enzyme E2 variant proteins constitute a distinct subfamily within the E2 protein family.
# Structure
UBE2V2 has sequence similarity to other ubiquitin-conjugating enzymes but lack the conserved cysteine residue that is critical for the catalytic activity of E2s. The protein encoded by this gene also shares homology with ubiquitin-conjugating enzyme E2 variant 1 and yeast MMS2 gene product.[3]
# Function
UBE2V2 has also been implicated as an intracellular sensor of reactive electrophilic species, which are present in high levels during periods of pathogenic and/or environmental stress.[4] The C69 residue of UBE2V2 is capable of binding with various RES. It has been shown that binding of RES to UBE2V2 promotes UBE2V2-mediated activation of Ube2N, another E2 protein that complexes with UBE2V2. Activated Ube2N has been shown to play a major role in promoting DNA-damage responses. Thus, UBE2V2 may promote genome integrity by directly sensing RES and effecting DNA damage responses.[5] It may also be involved in the differentiation of monocytes and enterocytes.[3]
# Interactions
UBE2V2 has been shown to interact with HLTF.[6] Although UBE2V2 itself lacks ubiquitin-conjugating activity, it can interact with different Ubiquitin-conjugating enzymes to facilitate their catalytic activities.[7] For instance, UBE2V2 can complex with UBE2N to form a heterodimer capable of synthesizing Lys-63 linked polyubiquitin chains.[8] UBE2V2 may facilitate UBE2N activity by coordinating UBE2N's positioning to promote ubiquitin chain formation specifically at Lys-63, as the ubiquitin molecule has multiple potential Lysine binding sites.[9] Similarly, it has been shown that UBE2V2 interact with the ubiquitin-conjugating enzyme, Ubc13, to induce Ubc13 to adopt an active conformation that can create Lys-63 polyubituitin chains on various substrates.[10]
Addition of Lys-63 polyubiquitin chains to intracellular targets is distinct from the canonical Lys-48 polyubiquitin chains in that Lys-63 chains do not mediate proteasomal degradation of its substrate.[11] Although their function remains poorly characterized, Lys-63 chains have been shown to regulate signaling pathways by either activating or inhibiting its target protein function.[12] For example, TRIM5alpha restriction of retroviral reverse-transcription is dependent on UBE2V2/UBE2N-mediated poly-ubiquitination.[13] UBE2V2 has been shown to regulate TRIM21 antiviral activity in an analogous manner.[14] | https://www.wikidoc.org/index.php/UBE2V2 | |
141eea28d750aa92bf86bcb1c6957ea76d883d24 | wikidoc | UBQLN1 | UBQLN1
Ubiquilin-1 is a protein that in humans is encoded by the UBQLN1 gene.
Ubiquilins contain a N-terminal ubiquitin-like domain and a C-terminal ubiquitin-associated domain. They physically associate with both proteasomes and ubiquitin ligases, and thus are thought to functionally link the ubiquitination machinery to the proteasome to effect in vivo protein degradation.
# Possible Role In Preventing Alzheimers Disease
Ubiquilin has also been shown to modulate accumulation of presenilin proteins, and is found in lesions associated with Alzheimer's and Parkinson's disease. Two transcript variants encoding different isoforms have been found for this gene.
Higher levels of ubiquilin-1 in the brain decreased malformation of the APP molecule which plays a key role in triggering Alzheimers disease. Conversely, lower levels of ubiquilin-1 in the brain were associated with increased malformation of APP.
# Similarity to Other Proteins
Human UBQLN1 shares a high degree of similarity with related ubiquilins including UBQLN2 and UBQLN4.
# Interactions
UBQLN1 has been shown to interact with
- HERPUD1,
- MTOR,
- P4HB,
- PSEN1
- PSEN2, and
- UBE3A.
- TMCO6, | UBQLN1
Ubiquilin-1 is a protein that in humans is encoded by the UBQLN1 gene.[1][2][3]
Ubiquilins contain a N-terminal ubiquitin-like domain and a C-terminal ubiquitin-associated domain. They physically associate with both proteasomes and ubiquitin ligases, and thus are thought to functionally link the ubiquitination machinery to the proteasome to effect in vivo protein degradation.
# Possible Role In Preventing Alzheimers Disease
Ubiquilin has also been shown to modulate accumulation of presenilin proteins, and is found in lesions associated with Alzheimer's and Parkinson's disease. Two transcript variants encoding different isoforms have been found for this gene.[3]
Higher levels of ubiquilin-1 in the brain decreased malformation of the APP molecule which plays a key role in triggering Alzheimers disease.[4] Conversely, lower levels of ubiquilin-1 in the brain were associated with increased malformation of APP.[4]
# Similarity to Other Proteins
Human UBQLN1 shares a high degree of similarity with related ubiquilins including UBQLN2 and UBQLN4.[5]
# Interactions
UBQLN1 has been shown to interact with
- HERPUD1,[6]
- MTOR,[7]
- P4HB,[8]
- PSEN1[9]
- PSEN2,[9] and
- UBE3A.[10]
- TMCO6,[11] | https://www.wikidoc.org/index.php/UBQLN1 | |
f533f9105e3ecb05df0a918e7e60ff65007289c4 | wikidoc | UBQLN2 | UBQLN2
Ubiquilin-2 is a protein that in humans is encoded by the UBQLN2 gene.
# Function
This gene encodes a ubiquitin-like protein (ubiquilin) that shares high degree of similarity with related products in yeast, rat and frog. Ubiquilins contain a N-terminal ubiquitin-like domain and a C-terminal ubiquitin-associated domain. They physically associate with both proteasomes and ubiquitin ligases, and are thus thought to functionally link the ubiquitination machinery to the proteasome to effect in vivo protein degradation. This ubiquilin has also been shown to bind the ATPase domain of the Hsp70-like Stch protein.
# Similarity to other proteins
Human UBQLN2 shares a high degree of similarity with related ubiquilins including UBQLN1 and UBQLN4.
# Clinical significance
In a small proportion of familial amyotrophic lateral sclerosis (fALS), the UBQLN2 gene is mutated, causing formation of a non-functional Ubiquilin 2 enzyme. This non-functioning enzyme leads to the accumulation of ubiquinated proteins in the lower motor neurons and upper corticospinal motor neurons, due to the fact that ubiquilin 2 normally degrades these ubiquinated proteins, but cannot if the ALS mutation is present. The same accumulations occur in patients without UBQLN2 mutations, but with mutations in other genes, including TDP-43 and C9ORF72.
# Interactions
UBQLN2 has been shown to interact with HERPUD1 and UBE3A. | UBQLN2
Ubiquilin-2 is a protein that in humans is encoded by the UBQLN2 gene.[1][2]
# Function
This gene encodes a ubiquitin-like protein (ubiquilin) that shares high degree of similarity with related products in yeast, rat and frog. Ubiquilins contain a N-terminal ubiquitin-like domain and a C-terminal ubiquitin-associated domain. They physically associate with both proteasomes and ubiquitin ligases, and are thus thought to functionally link the ubiquitination machinery to the proteasome to effect in vivo protein degradation. This ubiquilin has also been shown to bind the ATPase domain of the Hsp70-like Stch protein.[2]
# Similarity to other proteins
Human UBQLN2 shares a high degree of similarity with related ubiquilins including UBQLN1 and UBQLN4.[3]
# Clinical significance
In a small proportion of familial amyotrophic lateral sclerosis (fALS), the UBQLN2 gene is mutated, causing formation of a non-functional Ubiquilin 2 enzyme. This non-functioning enzyme leads to the accumulation of ubiquinated proteins in the lower motor neurons and upper corticospinal motor neurons, due to the fact that ubiquilin 2 normally degrades these ubiquinated proteins, but cannot if the ALS mutation is present.[4] The same accumulations occur in patients without UBQLN2 mutations, but with mutations in other genes, including TDP-43 and C9ORF72.
# Interactions
UBQLN2 has been shown to interact with HERPUD1[5] and UBE3A.[6] | https://www.wikidoc.org/index.php/UBQLN2 | |
038789bfe2bb331db32f31e050c494b02d1097d4 | wikidoc | UGT2B7 | UGT2B7
UGT2B7 (UDP-Glucuronosyltransferase-2B7) is a phase II metabolism isoenzyme found to be active in the liver, kidneys, epithelial cells of the lower gastrointestinal tract and also has been reported in the brain. In humans, UDP-Glucuronosyltransferase-2B7 is encoded by the UGT2B7 gene.
# Function
The UGTs serve a major role in the conjugation and subsequent elimination of potentially toxic xenobiotics and endogenous compounds. UGT2B7 has unique specificity for 3,4-catechol estrogens and estriol, suggesting that it may play an important role in regulating the level and activity of these potent estrogen metabolites.
This enzyme is located on the endoplasmic reticulum and nuclear membranes of cells. Its function is to catalyse the conjugation of a wide variety of lipophilic aglycon substrates with glucuronic acid, using uridine diphosphate glucuronic acid.
Together with UGT2B4, UGT2B7 is capable of glucosidation of hyodesoxycholic acid in the liver, but, unlike the 2B4 isoform, 2B7 is also able to glucuronidate various steroid hormones (androsterone, epitestosterone) and fatty acids. It is also able to conjugate major classes of drugs such as analgesics (morphine), carboxylic nonsteroidal anti-inflammatory drugs (ketoprofen), and anticarcinogens (all-trans retinoic acid). UGT2B7 is the major enzyme isoform for the metabolism of morphine to the main metabolites, morphine-3-glucuronide (M3G) which has no analgesic effect and morphine-6-glucuronide (M6G), which has analgesic effects more potent than morphine. As a consequence, altered UGT2B7 activity can significantly affect both the effectiveness and side-effects of morphine, as well as some related opiate drugs.
# Structure
No structure of a full human UGT enzyme has been determined yet, however Miley et al. resolved a partial UGT2B7 structure of the C-terminal portion showing two dimeric domains with Rossman-like folds in complex. The Rossman fold typically binds nucleotide substrates, in this case the UDP-glucuronic acid cofactor involved in glucuronidation by UGT2B7. Generally, the C-terminus of UGT enzymes is highly conserved and binds the UDP-glucuronic acid cofactor, while the N-terminus (not resolved in this structure) is responsible for substrate binding. This first resolved structure indicated that the C-terminus of one of the two dimers projected into the UDP-glucuronic acid binding site of the second dimer, thus rendering the second dimer ineffective.
Further studies have investigated dimerization of UGT enzyme polymorphisms and found both homodimer and heterodimer (with genetic polymorphisms of UGT2B7 or other UGT enzymes such as UGT1A1) formation are possible, with some combinations having an effect on enzyme activity.
# Genetic polymorphism
UGT2B7 is considered to be a highly polymorphic gene. Various research efforts have investigated the potential effect of these polymorphic variants on glucuronidation activity of UGT2B7 and especially its clearance of administered drugs, including anticancer therapies. Decreased glucuronidation activity by genetically variant UGT2B7 could lead to increased toxicity due to elevated levels of the drug remaining or accumulating in a patient's organs especially liver, while increased activity could mean lower efficacy of the administered therapy due to lower than expected levels in the body.
One study found that Han Chinese dye-industry workers exposed to benzidine were at higher risk for developing bladder cancer if they had the UGT2B7 single nucleotide polymorphism (SNP) C802T encoding His268Tyr. The histidine to tyrosine mutation at residue 268 is located in the N-terminal portion of UGT2B7, which binds the xenobiotic substrate as opposed to the C-terminus which binds UDP-glucuronic acid. The speculated mechanism for this increased cancer risk involved increased glucuronidation of benzidine by the mutant UGT2B7 followed by cleavage of the glucuronidated benzidine at urine pH levels, releasing higher concentrations of benzidine in the bladder. Another study looked for a similar association of variant UGT2B7 G900A with the risk of colorectal cancer but found no significant association.
A study of erlotinib clearance in non-small cell lung cancer patients showed no statistical significance for SNPs of UGT2B7, which potentially metabolizes erlotinib as indicated by erlotinib inhibition of UGT2B7. An investigation into the clearance of diclofenac, a nonsteroidal anti-inflammatory drug (NSAID) that can cause serious drug-induced liver injury, showed that mutant UGT2B7 with the C802T SNP had a 6-fold lower clearance of diclofenac than wild-type UGT27B, possibly contributing to increased liver toxicity in patients with this mutation. Analysis of genetic polymorphisms of UGT2B7 in anti-tuberculosis drug-induced liver injury (ATLI) found no association between mutations of UGT2B7 and ATLI in the studied population.
UGT2B7 is also known to be involved in the metabolism of opioids via glucuronidation, and a study investigating the effect of polymorphisms on the analgesic efficacy of buprenorphine found that the mutation C802T significantly worsened the analgesic response to buprenorphine after thoracic surgery, particularly at longer time-points (48 hours) where this long-lasting opioid is meant to remain effective. This same variant was found separately to have significant effects on the blood plasma concentration of valproic acid administered to epilepsy patients, which may account for some of the individual variability seen with this narrow-therapeutic window treatment. Both of these cases indicate decreased concentrations of drug compound probably due to increased glucuronidation activity of UGT2B7 with the C802T polymorphism.
Since UGT2B7 is involved in glucuronidation of many xenobiotic compounds, and polymorphisms of UGT2B7 are prevalent, investigation into potential effects of polymorphisms of UGT2B7 on clearance of pharmacologically relevant compounds is often of interest, as shown by the variety of studies undertaken. The UGT2B7 C802T polymorphism, for example, has been noted at 73% prevalence in Asians and 46% prevalence in Caucasians; therefore, effects of this polymorphism could impact a large portion of the population. However, not all studies find significant changes in clearance due to these genetic polymorphisms. It is not always clear if this is due to the particular polymorphism not affecting enzyme activity of UGT2B7, or because the compound of interest is metabolized by various routes that can mask any differences due to changes in UGT2B7 activity. | UGT2B7
UGT2B7 (UDP-Glucuronosyltransferase-2B7) is a phase II metabolism isoenzyme found to be active in the liver, kidneys, epithelial cells of the lower gastrointestinal tract and also has been reported in the brain. In humans, UDP-Glucuronosyltransferase-2B7 is encoded by the UGT2B7 gene.[1][2]
# Function
The UGTs serve a major role in the conjugation and subsequent elimination of potentially toxic xenobiotics and endogenous compounds. UGT2B7 has unique specificity for 3,4-catechol estrogens and estriol, suggesting that it may play an important role in regulating the level and activity of these potent estrogen metabolites.
This enzyme is located on the endoplasmic reticulum and nuclear membranes of cells. Its function is to catalyse the conjugation of a wide variety of lipophilic aglycon substrates with glucuronic acid, using uridine diphosphate glucuronic acid.
Together with UGT2B4, UGT2B7 is capable of glucosidation of hyodesoxycholic acid in the liver, but, unlike the 2B4 isoform, 2B7 is also able to glucuronidate various steroid hormones (androsterone, epitestosterone) and fatty acids.[3][4] It is also able to conjugate major classes of drugs such as analgesics (morphine), carboxylic nonsteroidal anti-inflammatory drugs (ketoprofen), and anticarcinogens (all-trans retinoic acid).[4] UGT2B7 is the major enzyme isoform for the metabolism of morphine to the main metabolites, morphine-3-glucuronide (M3G) which has no analgesic effect and morphine-6-glucuronide (M6G),[5] which has analgesic effects more potent than morphine.[6] As a consequence, altered UGT2B7 activity can significantly affect both the effectiveness and side-effects of morphine, as well as some related opiate drugs.[7][8][9][10][11]
# Structure
No structure of a full human UGT enzyme has been determined yet, however Miley et al. resolved a partial UGT2B7 structure of the C-terminal portion showing two dimeric domains with Rossman-like folds in complex.[12][13] The Rossman fold typically binds nucleotide substrates, in this case the UDP-glucuronic acid cofactor involved in glucuronidation by UGT2B7. Generally, the C-terminus of UGT enzymes is highly conserved and binds the UDP-glucuronic acid cofactor, while the N-terminus (not resolved in this structure) is responsible for substrate binding.[14] This first resolved structure indicated that the C-terminus of one of the two dimers projected into the UDP-glucuronic acid binding site of the second dimer, thus rendering the second dimer ineffective.
Further studies have investigated dimerization of UGT enzyme polymorphisms and found both homodimer and heterodimer (with genetic polymorphisms of UGT2B7 or other UGT enzymes such as UGT1A1) formation are possible, with some combinations having an effect on enzyme activity.[15]
# Genetic polymorphism
UGT2B7 is considered to be a highly polymorphic gene.[15] Various research efforts have investigated the potential effect of these polymorphic variants on glucuronidation activity of UGT2B7 and especially its clearance of administered drugs, including anticancer therapies. Decreased glucuronidation activity by genetically variant UGT2B7 could lead to increased toxicity due to elevated levels of the drug remaining or accumulating in a patient's organs especially liver, while increased activity could mean lower efficacy of the administered therapy due to lower than expected levels in the body.
One study found that Han Chinese dye-industry workers exposed to benzidine were at higher risk for developing bladder cancer if they had the UGT2B7 single nucleotide polymorphism (SNP) C802T encoding His268Tyr.[16] The histidine to tyrosine mutation at residue 268 is located in the N-terminal portion of UGT2B7, which binds the xenobiotic substrate as opposed to the C-terminus which binds UDP-glucuronic acid. The speculated mechanism for this increased cancer risk involved increased glucuronidation of benzidine by the mutant UGT2B7 followed by cleavage of the glucuronidated benzidine at urine pH levels, releasing higher concentrations of benzidine in the bladder. Another study looked for a similar association of variant UGT2B7 G900A with the risk of colorectal cancer but found no significant association.[17]
A study of erlotinib clearance in non-small cell lung cancer patients showed no statistical significance for SNPs of UGT2B7, which potentially metabolizes erlotinib as indicated by erlotinib inhibition of UGT2B7.[18] An investigation into the clearance of diclofenac, a nonsteroidal anti-inflammatory drug (NSAID) that can cause serious drug-induced liver injury, showed that mutant UGT2B7 with the C802T SNP had a 6-fold lower clearance of diclofenac than wild-type UGT27B, possibly contributing to increased liver toxicity in patients with this mutation.[19] Analysis of genetic polymorphisms of UGT2B7 in anti-tuberculosis drug-induced liver injury (ATLI) found no association between mutations of UGT2B7 and ATLI in the studied population.[20]
UGT2B7 is also known to be involved in the metabolism of opioids via glucuronidation, and a study investigating the effect of polymorphisms on the analgesic efficacy of buprenorphine found that the mutation C802T significantly worsened the analgesic response to buprenorphine after thoracic surgery, particularly at longer time-points (48 hours) where this long-lasting opioid is meant to remain effective.[21] This same variant was found separately to have significant effects on the blood plasma concentration of valproic acid administered to epilepsy patients, which may account for some of the individual variability seen with this narrow-therapeutic window treatment.[22] Both of these cases indicate decreased concentrations of drug compound probably due to increased glucuronidation activity of UGT2B7 with the C802T polymorphism.
Since UGT2B7 is involved in glucuronidation of many xenobiotic compounds, and polymorphisms of UGT2B7 are prevalent, investigation into potential effects of polymorphisms of UGT2B7 on clearance of pharmacologically relevant compounds is often of interest, as shown by the variety of studies undertaken. The UGT2B7 C802T polymorphism, for example, has been noted at 73% prevalence in Asians and 46% prevalence in Caucasians; therefore, effects of this polymorphism could impact a large portion of the population.[23] However, not all studies find significant changes in clearance due to these genetic polymorphisms. It is not always clear if this is due to the particular polymorphism not affecting enzyme activity of UGT2B7, or because the compound of interest is metabolized by various routes that can mask any differences due to changes in UGT2B7 activity. | https://www.wikidoc.org/index.php/UDP-glucuronosyl_transferase-2B7 | |
947a864358e107125e83de3cf4fc77656fde3004 | wikidoc | UGT1A1 | UGT1A1
This gene encodes a UDP-glucuronosyltransferase, an enzyme of the glucuronidation pathway that transforms small lipophilic molecules, such as steroids, bilirubin, hormones, and drugs, into water-soluble, excretable metabolites. This gene is part of a complex locus that encodes several UDP-glucuronosyltransferases. The locus includes thirteen unique alternate first exons followed by four common exons. Four of the alternate first exons are considered pseudogenes. Each of the remaining nine 5' exons may be spliced to the four common exons, resulting in nine proteins with different N-termini and identical C-termini. Each first exon encodes the substrate binding site, and is regulated by its own promoter. The preferred substrate of this enzyme is bilirubin, although it also has moderate activity with simple phenols, flavones, and C18 steroids. Mutations in this gene result in Crigler-Najjar syndromes types I and II and in Gilbert syndrome.
UGT1A1 is a gene associated with Crigler-Najjar syndrome, and a common splice variant is associated with serious side effects to the common chemotherapeutic drug irinotecan. The primary function of the gene's protein product is uridine diphospate glycosyltrasnferase 1 and is involved in the conversion of lipophilic molocules to water soluble substances suitable for excretion via substrate glycosylation.
Lack of expression of UGT1A1 in the neonatal liver is the major cause of jaundice in newborns. This jaundice is generally caused by massive breakdown of fetal blood cells which produces bilirubin which cannot be cleared if UGT1A1 is expressed at low levels or is absent. This type of jaundice can remedied by UV light exposure.
It transports bilirubin and phenol. | UGT1A1
This gene encodes a UDP-glucuronosyltransferase, an enzyme of the glucuronidation pathway that transforms small lipophilic molecules, such as steroids, bilirubin, hormones, and drugs, into water-soluble, excretable metabolites. This gene is part of a complex locus that encodes several UDP-glucuronosyltransferases. The locus includes thirteen unique alternate first exons followed by four common exons. Four of the alternate first exons are considered pseudogenes. Each of the remaining nine 5' exons may be spliced to the four common exons, resulting in nine proteins with different N-termini and identical C-termini. Each first exon encodes the substrate binding site, and is regulated by its own promoter. The preferred substrate of this enzyme is bilirubin, although it also has moderate activity with simple phenols, flavones, and C18 steroids. Mutations in this gene result in Crigler-Najjar syndromes types I and II and in Gilbert syndrome.[1]
UGT1A1 is a gene associated with Crigler-Najjar syndrome, and a common splice variant is associated with serious side effects to the common chemotherapeutic drug irinotecan. The primary function of the gene's protein product is uridine diphospate glycosyltrasnferase 1 and is involved in the conversion of lipophilic molocules to water soluble substances suitable for excretion via substrate glycosylation.
Lack of expression of UGT1A1 in the neonatal liver is the major cause of jaundice in newborns. This jaundice is generally caused by massive breakdown of fetal blood cells which produces bilirubin which cannot be cleared if UGT1A1 is expressed at low levels or is absent. This type of jaundice can remedied by UV light exposure.
It transports bilirubin and phenol. | https://www.wikidoc.org/index.php/UGT1A1 | |
63cdcec3be317356d5d90f6fe26928a11a673549 | wikidoc | UGT1A6 | UGT1A6
UDP-glucuronosyltransferase 1-6 is an enzyme that in humans is encoded by the UGT1A6 gene.
# Function
UDP-glucuronosyltransferase 1-6 is a UDP-glucuronosyltransferase, an enzyme of the glucuronidation pathway that transforms small lipophilic molecules, such as steroids, bilirubin, hormones, and drugs, into water-soluble, excretable metabolites.
This gene is part of a complex locus that encodes several UDP-glucuronosyltransferases. The locus includes thirteen unique alternate first exons followed by four common exons. Four of the alternate first exons are considered pseudogenes. Each of the remaining nine 5' exons may be spliced to the four common exons, resulting in nine proteins with different N-termini and identical C-termini. Each first exon encodes the substrate binding site, and is regulated by its own promoter. The enzyme encoded by this gene is active on phenolic and planar compounds. Alternative splicing in the unique 5' end of this gene results in two transcript variants.
UDP-glucuronosyltransferase is also responsible for the inactivation of popular analgesic drugs, such as aspirin and acetaminophen, by glucuronidation. The loss of a functional UGT1A6 gene in certain hypercarnivores, and particularly cats, renders the animals extremely sensitive to the adverse effects of these analgesics. | UGT1A6
UDP-glucuronosyltransferase 1-6 is an enzyme that in humans is encoded by the UGT1A6 gene.[1][2][3]
# Function
UDP-glucuronosyltransferase 1-6 is a UDP-glucuronosyltransferase, an enzyme of the glucuronidation pathway that transforms small lipophilic molecules, such as steroids, bilirubin, hormones, and drugs, into water-soluble, excretable metabolites.
This gene is part of a complex locus that encodes several UDP-glucuronosyltransferases. The locus includes thirteen unique alternate first exons followed by four common exons. Four of the alternate first exons are considered pseudogenes. Each of the remaining nine 5' exons may be spliced to the four common exons, resulting in nine proteins with different N-termini and identical C-termini. Each first exon encodes the substrate binding site, and is regulated by its own promoter. The enzyme encoded by this gene is active on phenolic and planar compounds. Alternative splicing in the unique 5' end of this gene results in two transcript variants.[3]
UDP-glucuronosyltransferase is also responsible for the inactivation of popular analgesic drugs, such as aspirin and acetaminophen, by glucuronidation. The loss of a functional UGT1A6 gene in certain hypercarnivores, and particularly cats, renders the animals extremely sensitive to the adverse effects of these analgesics.[4] | https://www.wikidoc.org/index.php/UGT1A6 | |
dc17e31950f141c93f1e7eb96c711d9ea6438965 | wikidoc | UGT1A9 | UGT1A9
UDP-glucuronosyltransferase 1-9 is an enzyme that in humans is encoded by the UGT1A9 gene.
# Function
This gene encodes a UDP-glucuronosyltransferase, an enzyme of the glucuronidation pathway that transforms small lipophilic molecules, such as steroids, bilirubin, hormones, and drugs, into water-soluble, excretable metabolites. This gene is part of a complex locus that encodes several UDP-glucuronosyltransferases. The locus includes thirteen unique alternate first exons followed by four common exons. Four of the alternate first exons are considered pseudogenes. Each of the remaining nine 5′ exons may be spliced to the four common exons, resulting in nine proteins with different N-termini and identical C-termini. Each first exon encodes the substrate binding site, and is regulated by its own promoter. The enzyme encoded by this gene is active on phenols.
# Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles.
- ↑ The interactive pathway map can be edited at WikiPathways: "IrinotecanPathway_WP46359"..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"\"""\"""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{display:none;font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em} | UGT1A9
UDP-glucuronosyltransferase 1-9 is an enzyme that in humans is encoded by the UGT1A9 gene.[1][2][3][4]
# Function
This gene encodes a UDP-glucuronosyltransferase, an enzyme of the glucuronidation pathway that transforms small lipophilic molecules, such as steroids, bilirubin, hormones, and drugs, into water-soluble, excretable metabolites. This gene is part of a complex locus that encodes several UDP-glucuronosyltransferases. The locus includes thirteen unique alternate first exons followed by four common exons. Four of the alternate first exons are considered pseudogenes. Each of the remaining nine 5′ exons may be spliced to the four common exons, resulting in nine proteins with different N-termini and identical C-termini. Each first exon encodes the substrate binding site, and is regulated by its own promoter. The enzyme encoded by this gene is active on phenols.[4]
# Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles. [§ 1]
- ↑ The interactive pathway map can be edited at WikiPathways: "IrinotecanPathway_WP46359"..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"\"""\"""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{display:none;font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em} | https://www.wikidoc.org/index.php/UGT1A9 | |
a36018e165e7e61cb46e3cd51e24ec37626c0c7c | wikidoc | UGT2B4 | UGT2B4
UDP glucuronosyltransferase 2 family, polypeptide B4, also known as UGT2B4, is an enzyme that in humans is encoded by the UGT2B4 gene.
# Function
UGT2B4 is mainly involved in the glucuronidation of hyodeoxycholic acid, a bile acid, and catechol-estrogens, such as 17-epiestriol and 4-hydroxy-estrone.
The expression of the UGT2B4 enzyme is upregulated by the farnesoid X receptor (FXR), a nuclear receptor which is activated by bile acids. These same bile acids are substrates for the UGT2B4 enzyme. Hence upregulation of UGT2B4 by activated FXR provides a mechanism for the detection, conjugation and subsequent elimination of toxic bile acids. | UGT2B4
UDP glucuronosyltransferase 2 family, polypeptide B4, also known as UGT2B4, is an enzyme that in humans is encoded by the UGT2B4 gene.[1][2][3]
# Function
UGT2B4 is mainly involved in the glucuronidation of hyodeoxycholic acid, a bile acid, and catechol-estrogens, such as 17-epiestriol and 4-hydroxy-estrone.[4]
The expression of the UGT2B4 enzyme is upregulated by the farnesoid X receptor (FXR), a nuclear receptor which is activated by bile acids.[5] These same bile acids are substrates for the UGT2B4 enzyme. Hence upregulation of UGT2B4 by activated FXR provides a mechanism for the detection, conjugation and subsequent elimination of toxic bile acids. | https://www.wikidoc.org/index.php/UGT2B4 | |
bd38ccdda7a3f5673b65bed228fa40a9dc8b4f0a | wikidoc | UNC13A | UNC13A
Unc-13 homolog A (C. elegans) is a protein that in humans is encoded by the UNC13A gene.
# Function
This gene encodes a member of the UNC13 family. UNC13A plays a role in vesicle maturation during exocytosis as a target of the diacylglycerol second messenger pathway. It is involved in neurotransmitter release by acting in synaptic vesicle priming prior to vesicle fusion and participates in the activity-dependent refilling of readily releasable vesicle pool. In Drosophila melanogaster, the protein has been shown to define the vesicle release site by regulating the coupling distance between synaptic vesicles and calcium channels in cooperation with another isoform, UNC13B. It is particularly important in most glutamatergic-mediated synapses but not GABA-mediated synapses. It plays a role in dendrite formation by melanocytes and in secretory granule priming in insulin secretion.
# Protein structure
Several conserved domains have been found in UNC13A. These conserved domains include three C2 domains. One C2 domain is centrally located, another is at the carboxyl end, and there is a third. In addition, there is one C1 domain, as well as Munc13 homology domains 1 (MHD1) and 2 (MHD2).
# Subcellular location
UNC13A is localized to the active zone of presynaptic density. It is translocated to the plasma membrane in response to phorbol ester binding.
# Interaction
UNC13A has been shown to interact with:
- STX1A,
- STX1B1,
- DOC2A,
- BSN,
- RIMS1,
- RIMS2,
- ERC2, and
- RAB3A.
# Clinical significance
Single nucleotide polymorphisms in this gene may be associated with sporadic amyotrophic lateral sclerosis. This single nucleotide polymorphism has been discovered on chromosome 19. This variation of the single nucleotide involving UNC13A has also been implicated in frontotemporal dementia (FTD). Pathology involving TDP-43 is a result of the single nucleotide polymorphisms in both ALS and FTD. This gene has also been associated with Alzheimer's Disease (AD). | UNC13A
Unc-13 homolog A (C. elegans) is a protein that in humans is encoded by the UNC13A gene.[1]
# Function
This gene encodes a member of the UNC13 family.[1] UNC13A plays a role in vesicle maturation during exocytosis as a target of the diacylglycerol second messenger pathway. It is involved in neurotransmitter release by acting in synaptic vesicle priming prior to vesicle fusion and participates in the activity-dependent refilling of readily releasable vesicle pool. In Drosophila melanogaster, the protein has been shown to define the vesicle release site by regulating the coupling distance between synaptic vesicles and calcium channels in cooperation with another isoform, UNC13B.[2] It is particularly important in most glutamatergic-mediated synapses but not GABA-mediated synapses. It plays a role in dendrite formation by melanocytes and in secretory granule priming in insulin secretion.[3]
# Protein structure
Several conserved domains have been found in UNC13A. These conserved domains include three C2 domains. One C2 domain is centrally located, another is at the carboxyl end, and there is a third. In addition, there is one C1 domain, as well as Munc13 homology domains 1 (MHD1) and 2 (MHD2).[3][4]
# Subcellular location
UNC13A is localized to the active zone of presynaptic density. It is translocated to the plasma membrane in response to phorbol ester binding.[3]
# Interaction
UNC13A has been shown to interact with:
- STX1A,[3]
- STX1B1,[3]
- DOC2A,[3]
- BSN,[3]
- RIMS1,[3]
- RIMS2,[3]
- ERC2,[3] and
- RAB3A.[3]
# Clinical significance
Single nucleotide polymorphisms in this gene may be associated with sporadic amyotrophic lateral sclerosis.[5][6][7][8] This single nucleotide polymorphism has been discovered on chromosome 19. This variation of the single nucleotide involving UNC13A has also been implicated in frontotemporal dementia (FTD). Pathology involving TDP-43 is a result of the single nucleotide polymorphisms in both ALS and FTD.[9] This gene has also been associated with Alzheimer's Disease (AD).[10] | https://www.wikidoc.org/index.php/UNC13A | |
df97477dd0715aa9d02d2529e983d2cd48e1efa9 | wikidoc | UNC13D | UNC13D
Protein unc-13 homolog D, also known as munc13-4, is a protein that in humans is encoded by the UNC13D gene.
# Function
Munc13-4 is a member of the UNC13 family, containing similar domain structure as other family members but lacking an N-terminal phorbol ester-binding C1 domain present in other Munc13 proteins. The protein appears to play a role in vesicle maturation during exocytosis and is involved in regulation of cytolytic granules secretion.
Munc13-4 is an essential protein in the intracellular trafficking and exocytosis of lytic granules. It is targeted to CD63 positive secretory lysosomes. The C-terminal C2 domain of the protein is involved in this process.
# Clinical significance
Mutations in the UNC13D gene are associated with hemophagocytic lymphohistiocytosis type 3. | UNC13D
Protein unc-13 homolog D, also known as munc13-4, is a protein that in humans is encoded by the UNC13D gene.[1]
# Function
Munc13-4 is a member of the UNC13 family, containing similar domain structure as other family members but lacking an N-terminal phorbol ester-binding C1 domain present in other Munc13 proteins. The protein appears to play a role in vesicle maturation during exocytosis and is involved in regulation of cytolytic granules secretion.
Munc13-4 is an essential protein in the intracellular trafficking and exocytosis of lytic granules. It is targeted to CD63 positive secretory lysosomes. The C-terminal C2 domain of the protein is involved in this process.[2]
# Clinical significance
Mutations in the UNC13D gene are associated with hemophagocytic lymphohistiocytosis type 3.[1] | https://www.wikidoc.org/index.php/UNC13D | |
9c1fc779ef199184293a104f46756b9aac38ebab | wikidoc | UNC93A | UNC93A
Unc-93 homolog A (C. elegans) is a protein that in humans is encoded by the UNC93A gene.
Unc93A is a major facilitator superfamily (MFS), and a putative solute carrier in humans. It belongs to the atypical SLCs that was recently listed. It is therefore presumed that UNC93A is a transporter protein.
UNC93A is closely related to Unc93B1 and MFSD11.
UNC93A is affected by amino acid deprivation in cell cortex cultures and starvation in in vivo samples.
It is expressed in neurons, with staining close to the plasma membrane.
Read also for functional studies in C.elegans. | UNC93A
Unc-93 homolog A (C. elegans) is a protein that in humans is encoded by the UNC93A gene.[1]
Unc93A is a major facilitator superfamily (MFS), and a putative solute carrier in humans.[2][3] It belongs to the atypical SLCs that was recently listed.[2] It is therefore presumed that UNC93A is a transporter protein.
UNC93A is closely related to Unc93B1 and MFSD11.[4][5]
UNC93A is affected by amino acid deprivation in cell cortex cultures[3][4] and starvation in in vivo samples.[4]
It is expressed in neurons, with staining close to the plasma membrane.[4]
Read also [6][7] for functional studies in C.elegans. | https://www.wikidoc.org/index.php/UNC93A | |
10f9328f067dc20c4c5587a0d08d27de2aa1df6b | wikidoc | UQCR11 | UQCR11
UQCR11 (ubiquinol-cytochrome c reductase, complex III sub-unit XI) is a protein that in humans is encoded by the UQCR11 gene. UQCR11 is the smallest known component of Complex III in the mitochondrial respiratory chain.
# Structure
The UQCR11 gene, located on the p arm of chromosome 19 in position 13.3, is made up of 3 exons and is 8,329 base pairs in length. The UQCR11 protein weighs 6.6 kDa and is composed of 56 amino acids. This gene encodes the smallest known component of the ubiquinol-cytochrome c reductase complex, which is also known as Complex III and is part of the mitochondrial respiratory chain. In vertebrates, Complex III contains 11 sub-units: 3 respiratory sub-units, 2 core proteins and 6 low-molecular weight proteins. Proteobacterial complexes may contain as few as three sub-units.
# Function
The UQCR11 protein may function as a binding factor for the iron-sulfur protein in Complex III, which is ubiquitous in human cells. Complex III catalyzes the chemical reaction
Thus, the two substrates of Complex III are dihydroquinone (QH2) and ferri- (Fe3+) cytochrome c, whereas its 3 products are quinone (Q), ferro- (Fe2+) cytochrome c, and H+. This complex belongs to the family of oxidoreductases, specifically those acting on diphenols and related substances as donor with a cytochrome as acceptor. This enzyme participates in oxidative phosphorylation. It has four cofactors: cytochrome c1, cytochrome b-562, cytochrome b-566 and a 2-Iron ferredoxin of the Rieske type. | UQCR11
UQCR11 (ubiquinol-cytochrome c reductase, complex III sub-unit XI) is a protein that in humans is encoded by the UQCR11 gene.[1][2] UQCR11 is the smallest known component of Complex III in the mitochondrial respiratory chain.[2]
# Structure
The UQCR11 gene, located on the p arm of chromosome 19 in position 13.3, is made up of 3 exons and is 8,329 base pairs in length.[2] The UQCR11 protein weighs 6.6 kDa and is composed of 56 amino acids.[3][4] This gene encodes the smallest known component of the ubiquinol-cytochrome c reductase complex, which is also known as Complex III and is part of the mitochondrial respiratory chain.[2] In vertebrates, Complex III contains 11 sub-units: 3 respiratory sub-units, 2 core proteins and 6 low-molecular weight proteins.[5][6] Proteobacterial complexes may contain as few as three sub-units.[7]
# Function
The UQCR11 protein may function as a binding factor for the iron-sulfur protein in Complex III, which is ubiquitous in human cells.[2] Complex III catalyzes the chemical reaction
Thus, the two substrates of Complex III are dihydroquinone (QH2) and ferri- (Fe3+) cytochrome c, whereas its 3 products are quinone (Q), ferro- (Fe2+) cytochrome c, and H+. This complex belongs to the family of oxidoreductases, specifically those acting on diphenols and related substances as donor with a cytochrome as acceptor. This enzyme participates in oxidative phosphorylation. It has four cofactors: cytochrome c1, cytochrome b-562, cytochrome b-566 and a 2-Iron ferredoxin of the Rieske type. | https://www.wikidoc.org/index.php/UQCR11 | |
6f05a1ab0c76d322cb18b41636872d9aaf0d2bf0 | wikidoc | UQCRC2 | UQCRC2
Cytochrome b-c1 complex subunit 2, mitochondrial (UQCRC2), also known as QCR2, UQCR2, or MC3DN5 is a protein that in humans is encoded by the UQCRC2 gene. The product of UQCRC2 is a subunit of the respiratory chain protein Ubiquinol Cytochrome c Reductase (UQCR, Complex III or Cytochrome bc1 complex), which consists of the products of one mitochondrially encoded gene, MTCYTB (mitochondrial cytochrome b) and ten nuclear genes: UQCRC1, UQCRC2, Cytochrome c1, UQCRFS1 (Rieske protein), UQCRB, "11kDa protein", UQCRH (cyt c1 Hinge protein), Rieske Protein presequence, "cyt. c1 associated protein", and "Rieske-associated protein." Defects in UQCRC2 are associated with mitochondrial complex III deficiency, nuclear, type 5.
# Structure
UQCRC2 is located on the p arm of chromosome 16 in position 12.2 and has 14 exons. The UQCRC2 gene produces a 48.4 kDa protein composed of 453 amino acids. UQCRC2 belongs to the peptidase M16 family and UQCRC2/QCR2 subfamily. UQCRC2 has a transit peptide domain. Ubiquinol Cytochrome c Reductase (b-c1 complex) contains 11 subunits: 3 respiratory subunits (cytochrome b, cytochrome c1 and Rieske/UQCRFS1), 2 core proteins (UQCRC1/QCR1 and UQCRC2/QCR2) and 6 low-molecular weight proteins (UQCRH/QCR6, UQCRB/QCR7, UQCRQ/QCR8, UQCR10/QCR9, UQCR11/QCR10 and a cleavage product of Rieske/UQCRFS1). UQCRC2 is part of the hydrophobic core of the b-c1 complex and is necessary for the stabilization of Ubiquinol Cytochrome c Reductase.
# Function
The protein encoded by this gene is located in the mitochondrion, where it is part of the ubiquinol-cytochrome c reductase complex (also known as complex III). This complex constitutes a part of the mitochondrial respiratory chain. The core protein UQCRC2 is required for the assembly and stabilization of the complex.
# Clinical Significance
Variants of UQCRC2 have been associated with mitochondrial complex III deficiency, nuclear, type 5. Mitochondrial complex III deficiency nuclear type 5 is a disorder of the mitochondrial respiratory chain resulting in a highly variable phenotype depending on which tissues are affected. Clinical features include mitochondrial encephalopathy, psychomotor retardation, ataxia, severe failure to thrive, liver dysfunction, renal tubulopathy, muscle weakness, exercise intolerance, lactic acidosis and hypoglycemia. Homozygous mutations resulting in a change from Arginine to Tryptophan at position 183 have been associated with mitochondrial complex III deficiency due to UQCRC2 dysfunction. Autosomal recessive inheritance has been proposed as a transmission pattern.
# Interactions
UQCRC2 has 98 protein-protein interactions with 90 of them being co-complex interactions. CAC1A, QCR1, UQCRC1, CACNA1A, STOM, a8k1f4, HLA-B, ARF6, and Mapk3 have been found to interact with UQCRC2. | UQCRC2
Cytochrome b-c1 complex subunit 2, mitochondrial (UQCRC2), also known as QCR2, UQCR2, or MC3DN5 is a protein that in humans is encoded by the UQCRC2 gene.[1] The product of UQCRC2 is a subunit of the respiratory chain protein Ubiquinol Cytochrome c Reductase (UQCR, Complex III or Cytochrome bc1 complex), which consists of the products of one mitochondrially encoded gene, MTCYTB (mitochondrial cytochrome b) and ten nuclear genes: UQCRC1, UQCRC2, Cytochrome c1, UQCRFS1 (Rieske protein), UQCRB, "11kDa protein", UQCRH (cyt c1 Hinge protein), Rieske Protein presequence, "cyt. c1 associated protein", and "Rieske-associated protein."[2][3] Defects in UQCRC2 are associated with mitochondrial complex III deficiency, nuclear, type 5.[1]
# Structure
UQCRC2 is located on the p arm of chromosome 16 in position 12.2 and has 14 exons.[1] The UQCRC2 gene produces a 48.4 kDa protein composed of 453 amino acids.[4][5] UQCRC2 belongs to the peptidase M16 family and UQCRC2/QCR2 subfamily. UQCRC2 has a transit peptide domain. Ubiquinol Cytochrome c Reductase (b-c1 complex) contains 11 subunits: 3 respiratory subunits (cytochrome b, cytochrome c1 and Rieske/UQCRFS1), 2 core proteins (UQCRC1/QCR1 and UQCRC2/QCR2) and 6 low-molecular weight proteins (UQCRH/QCR6, UQCRB/QCR7, UQCRQ/QCR8, UQCR10/QCR9, UQCR11/QCR10 and a cleavage product of Rieske/UQCRFS1).[6][7] UQCRC2 is part of the hydrophobic core of the b-c1 complex and is necessary for the stabilization of Ubiquinol Cytochrome c Reductase.[8]
# Function
The protein encoded by this gene is located in the mitochondrion, where it is part of the ubiquinol-cytochrome c reductase complex (also known as complex III). This complex constitutes a part of the mitochondrial respiratory chain.[1] The core protein UQCRC2 is required for the assembly and stabilization of the complex.[6][7]
# Clinical Significance
Variants of UQCRC2 have been associated with mitochondrial complex III deficiency, nuclear, type 5.[1] Mitochondrial complex III deficiency nuclear type 5 is a disorder of the mitochondrial respiratory chain resulting in a highly variable phenotype depending on which tissues are affected. Clinical features include mitochondrial encephalopathy, psychomotor retardation, ataxia, severe failure to thrive, liver dysfunction, renal tubulopathy, muscle weakness, exercise intolerance, lactic acidosis and hypoglycemia. Homozygous mutations resulting in a change from Arginine to Tryptophan at position 183 have been associated with mitochondrial complex III deficiency due to UQCRC2 dysfunction. Autosomal recessive inheritance has been proposed as a transmission pattern.[8][9][10]
# Interactions
UQCRC2 has 98 protein-protein interactions with 90 of them being co-complex interactions. CAC1A, QCR1, UQCRC1, CACNA1A, STOM, a8k1f4, HLA-B, ARF6, and Mapk3 have been found to interact with UQCRC2.[6][7][11] | https://www.wikidoc.org/index.php/UQCRC2 | |
3592935bad2c4c5dd6f208ba24c71d1eb2dc6987 | wikidoc | Upjohn | Upjohn
The Upjohn Company was a pharmaceutical manufacturing firm founded in 1886 in Kalamazoo, Michigan by Dr. William E. Upjohn, an 1875 graduate of the University of Michigan medical school. The company was originally formed to make friable pills, which were specifically designed to be easily digested.
In 1995, Upjohn merged with Pharmacia AB, to form Pharmacia & Upjohn. Today, through a series of mergers, the remainder of Upjohn is owned by Pfizer.
# Chemistry
In chemical research, the company is best known for the development of the Upjohn dihydroxylation by V. VanRheenen, R. C. Kelly and D. Y. Cha in 1976.
Upjohn research is best known for the process that made possible large scale production of cortisone. The oxygen atom at the 11 position in this steroid is an absolute requirement for biological activity. There are however no known natural sources for starting materials that contain that feature. The only method for preparing this drug prior to 1952 was a lengthy synthesis starting from cholic acid isolated from bile. In 1952 two Upjohn biochemists, Dury Peterson and Herb Murray announced that they were able to introduce this crucial oxygen atom by fermentation of the steroid progesterone with the mold Aspergillus nigercans Over the next several years a group of chemists headed by John Hogg developed a process for preparing cortisone from the soybean steroid stigmasterol. The microbiological oxygenation is a key step in this process.
Upjohn is also well known for manufacturing Xanax. | Upjohn
The Upjohn Company was a pharmaceutical manufacturing firm founded in 1886 in Kalamazoo, Michigan by Dr. William E. Upjohn, an 1875 graduate of the University of Michigan medical school. The company was originally formed to make friable pills, which were specifically designed to be easily digested.[1]
In 1995, Upjohn merged with Pharmacia AB, to form Pharmacia & Upjohn.[2] Today, through a series of mergers, the remainder of Upjohn is owned by Pfizer.
# Chemistry
In chemical research, the company is best known for the development of the Upjohn dihydroxylation by V. VanRheenen, R. C. Kelly and D. Y. Cha in 1976.[3]
Upjohn research is best known for the process that made possible large scale production of cortisone. The oxygen atom at the 11 position in this steroid is an absolute requirement for biological activity. There are however no known natural sources for starting materials that contain that feature. The only method for preparing this drug prior to 1952 was a lengthy synthesis starting from cholic acid isolated from bile. In 1952 two Upjohn biochemists, Dury Peterson and Herb Murray announced that they were able to introduce this crucial oxygen atom by fermentation of the steroid progesterone with the mold Aspergillus nigercans Over the next several years a group of chemists headed by John Hogg developed a process for preparing cortisone from the soybean steroid stigmasterol. The microbiological oxygenation is a key step in this process.
Upjohn is also well known for manufacturing Xanax. | https://www.wikidoc.org/index.php/Upjohn | |
a1b996a9b64cb7aa0058e8dee58b17f67e4ac462 | wikidoc | Uranyl | Uranyl
The uranyl ion is the dipositive cation 2+, which forms salts with acids. In this ion, uranium is in its +6 oxidation state. The other common oxidation state of uranium is uranium(IV), called uranous. The uranyl ion is the most common species encountered in the aqueous chemistry of uranium. Solid uranyl compounds are often colored red, yellow, orange or green. Like all uranium compounds, uranyl compounds are toxic. The toxicity of soluble uranyl salts is higher due to their faster incorporation into tissues.
# Examples
Examples of uranyl compounds include:
- Uranium trioxide, UO3
- Uranyl acetate, UO2(C2H3O2)2
- Uranyl ammonium carbonate, UO2CO3·2(NH4)2CO3
- Uranyl carbonate, UO2CO3
- Uranyl chloride, UO2Cl2
- Uranyl hydroxide, UO2(OH)2 or (UO2)2(OH)2 also in aqueous
- Uranyl nitrate, UO2(NO3)2
- Uranyl sulfate, UO2SO4
- Uranyl zinc acetate, ZnUO2(CH3COO)4
# Minerals
Such minerals occur in oxidised portions of uranium ore deposits. Common uranyl minerals include tyuyamunite (Ca(UO2)2V2O8·8H2O), autunite (Ca(UO2)2(PO4)2·8-12H2O), torbernite (Cu(UO2)2 (PO4)·8-12H2O) and uranophane (H3O)2Ca (UO2)2(SiO4)·3H2O) (Hutchinson and Blackwell, 1984).
Uranyl minerals, which contain uranium(VI) can help show the genesis of uranium deposits and the water-rock interactions that occur in uranium-rich mineral seams.
# Chemistry
Uranium chemistry has traditionally revolved around the aqueous chemistry of the uranyl ion, and related molecular species. One important use of this chemistry is for preparation of uranium dioxide ceramic pellets that are used as the fuel in light water nuclear reactors. Often the fuel materials start to break down chemically before the uranium is completely spent, and this too is an active area of investigation, as many of the corrosion products are of the uranyl group.
# Structure
The geometry of the uranyl ion has been the subject of much debate. The close approach of two oxygen atoms to uranium, with each linear O-U-O bond from 1.7 to 1.9 Å, prevents the close approach of a third or more. d-p and f-p bonding have been suggested to explain the short U-O bonds.
# Health and environmental issues
Uranyl nitrate is an oxidizing and highly toxic compound and should not be ingested; it causes severe renal insufficiency and acute tubular necrosis and is a lymphocyte mitogen.
Target organs include the kidneys, liver, lungs and brain.
Uranyl ion accumulation in tissues including gonocytes produces congenital disorders, and in white blood cells causes immune system damage. Uranyl compounds are also neurotoxins.
# Combustion of uranium
Aerial oxidation of any uranium compound eventually results in the formation of a uranyl compound. Uranyl ion contamination has been found on and around depleted uranium targets. | Uranyl
The uranyl ion is the dipositive cation [UO2]2+, which forms salts with acids. In this ion, uranium is in its +6 oxidation state. The other common oxidation state of uranium is uranium(IV), called uranous. The uranyl ion is the most common species encountered in the aqueous chemistry of uranium. Solid uranyl compounds are often colored red, yellow, orange or green. Like all uranium compounds, uranyl compounds are toxic. The toxicity of soluble uranyl salts is higher due to their faster incorporation into tissues.
# Examples
Examples of uranyl compounds include:
- Uranium trioxide, UO3
- Uranyl acetate, UO2(C2H3O2)2
- Uranyl ammonium carbonate, UO2CO3·2(NH4)2CO3
- Uranyl carbonate, UO2CO3
- Uranyl chloride, UO2Cl2
- Uranyl hydroxide, UO2(OH)2 or (UO2)2(OH)2 also in aqueous
- Uranyl nitrate, UO2(NO3)2
- Uranyl sulfate, UO2SO4
- Uranyl zinc acetate, ZnUO2(CH3COO)4
# Minerals
Such minerals occur in oxidised portions of uranium ore deposits. Common uranyl minerals include tyuyamunite (Ca(UO2)2V2O8·8H2O), autunite (Ca(UO2)2(PO4)2·8-12H2O), torbernite (Cu(UO2)2 (PO4)·8-12H2O) and uranophane (H3O)2Ca (UO2)2(SiO4)·3H2O) (Hutchinson and Blackwell, 1984).
Uranyl minerals, which contain uranium(VI) can help show the genesis of uranium deposits and the water-rock interactions that occur in uranium-rich mineral seams.
# Chemistry
Uranium chemistry has traditionally revolved around the aqueous chemistry of the uranyl ion, and related molecular species. One important use of this chemistry is for preparation of uranium dioxide ceramic pellets that are used as the fuel in light water nuclear reactors. Often the fuel materials start to break down chemically before the uranium is completely spent, and this too is an active area of investigation, as many of the corrosion products are of the uranyl group.
# Structure
The geometry of the uranyl ion has been the subject of much debate. The close approach of two oxygen atoms to uranium, with each linear O-U-O bond from 1.7 to 1.9 Å, prevents the close approach of a third or more. d-p and f-p bonding have been suggested to explain the short U-O bonds.[1]
# Health and environmental issues
Uranyl nitrate is an oxidizing and highly toxic compound and should not be ingested; it causes severe renal insufficiency and acute tubular necrosis and is a lymphocyte mitogen.
Target organs include the kidneys, liver, lungs and brain.
Uranyl ion accumulation in tissues including gonocytes[2] produces congenital disorders, and in white blood cells causes immune system damage.[3] Uranyl compounds are also neurotoxins.
# Combustion of uranium
Aerial oxidation of any uranium compound eventually results in the formation of a uranyl compound.[1] Uranyl ion contamination has been found on and around depleted uranium targets.[4] | https://www.wikidoc.org/index.php/Uranyl | |
6ef26b67d839fb385f884c61dbb87fca9e20d678 | wikidoc | Ureter | Ureter
Steven C. Campbell, M.D., Ph.D.
# Overview
In human anatomy, the ureters are the ducts that carry urine from the kidneys to the urinary bladder, passing anterior to the psoas major. The ureters are muscular tubes that can propel urine along by the motions of peristalsis. In the adult, the ureters are usually 25-30cm long.
In humans, the ureters enter the bladder through the back, running within the wall of the bladder for a few centimetres. There are no valves in the ureters, backflow being prevented by pressure from the filling of the bladder, as well as the tone of the muscle in the bladder wall.
In the female, the ureters pass through the mesometrium on the way to the urinary bladder.
# Histology
The ureter has a diameter of about 3 millimeters, and the lumen is star-shaped. Like the bladder, it is lined with transitional epithelium, and contains layers of smooth muscle.
The epithelial cells of the ureter are stratified (in many layers), are normally round in shape but become squamous (flat) when stretched. The lamina propria is thick and elastic (as it is important that it is impermeable).
There are two spiral layers of smooth muscle in the ureter wall, an inner loose spiral, and an outer tight spiral. The inner loose spiral is sometimes described as longitudinal, and the outer as circular, (this is the opposite to the situation in the gastrointestinal tract). The distal third of the ureter contains another layer of outer longitudinal muscle.
The adventitia of the ureter, like elsewhere is composed of fibrous connective tissue, that binds it to adjacent tissues.
# Diseases and disorders
Medical problems that can affect the ureter include:
- Cancer of the ureter
- Passage of kidney stones
- Ureterocele
- Megaureter
- Vesico-ureteric reflux
- Anatomical abnormalities, such as duplexing and ectopia | Ureter
Template:Infobox Anatomy
Steven C. Campbell, M.D., Ph.D.
# Overview
In human anatomy, the ureters are the ducts that carry urine from the kidneys to the urinary bladder, passing anterior to the psoas major. The ureters are muscular tubes that can propel urine along by the motions of peristalsis. In the adult, the ureters are usually 25-30cm long.
In humans, the ureters enter the bladder through the back, running within the wall of the bladder for a few centimetres. There are no valves in the ureters, backflow being prevented by pressure from the filling of the bladder, as well as the tone of the muscle in the bladder wall.
In the female, the ureters pass through the mesometrium on the way to the urinary bladder.
# Histology
The ureter has a diameter of about 3 millimeters, and the lumen is star-shaped. Like the bladder, it is lined with transitional epithelium, and contains layers of smooth muscle.
The epithelial cells of the ureter are stratified (in many layers), are normally round in shape but become squamous (flat) when stretched. The lamina propria is thick and elastic (as it is important that it is impermeable).
There are two spiral layers of smooth muscle in the ureter wall, an inner loose spiral, and an outer tight spiral. The inner loose spiral is sometimes described as longitudinal, and the outer as circular, (this is the opposite to the situation in the gastrointestinal tract). The distal third of the ureter contains another layer of outer longitudinal muscle.
The adventitia of the ureter, like elsewhere is composed of fibrous connective tissue, that binds it to adjacent tissues.
# Diseases and disorders
Medical problems that can affect the ureter include:
- Cancer of the ureter
- Passage of kidney stones
- Ureterocele
- Megaureter
- Vesico-ureteric reflux
- Anatomical abnormalities, such as duplexing and ectopia
# External links
- Template:SUNYAnatomyLabs - "Posterior Abdominal Wall: Internal Structure of a Kidney"
- Template:SUNYAnatomyFigs - "Relationship of the ureter to the uterine artery."
- Template:SUNYAnatomyFigs - "Mid-sagittal section of male pelvis."
- Template:SUNYAnatomyImage
- Template:SUNYAnatomyImage
- Template:IowaHistologyInteractive
- Template:UCDavisOrganology - "Mammal, ureter (LM, Medium)"
- Histology at KUMC urinary-renal15 - "Ureter"
- Template:ViennaCrossSection
# Additional images
- Bladder
- Frontal section through the kidney
- Wall of the ureter.
- Transverse section of human embryo eight and a half to nine weeks old.
- Tail end of human embryo thirty-two to thirty-three days old.
- The relations of the viscera and large vessels of the abdomen. (Seen from behind, the last thoracic vertebra being well raised.)
- The posterior surfaces of the kidneys, showing areas of relation to the parietes.
- Vertical section of kidney.
- Transverse section of ureter.
- The interior of bladder.
- Fundus of the bladder with the vesiculæ seminales.
- Median sagittal section of male pelvis.
Template:Urinary system
ar:حالب
cs:Močovod
de:Harnleiter
id:Ureter
it:Uretere
he:שופכן
ku:Mîzlûl
lt:Šlapimtakis
nl:Urineleider
no:Urinleder
sk:Močovod
sr:Мокраћовод
sh:Mokraćovod
fi:Virtsanjohdin
Template:WikiDoc Sources | https://www.wikidoc.org/index.php/Ureter | |
a2d91e9f9aceff8b1336d517f00acd0c81c26eea | wikidoc | VEGFR1 | VEGFR1
Vascular endothelial growth factor receptor 1 is a protein that in humans is encoded by the FLT1 gene.
# Function
Oncogene FLT belongs to the src gene family and is related to oncogene ROS (MIM 165020). Like other members of this family, it shows tyrosine protein kinase activity that is important for the control of cell proliferation and differentiation. The sequence structure of the FLT gene resembles that of the FMS gene (MIM 164770); hence, Yoshida et al. (1987) proposed the name FLT as an acronym for FMS-like tyrosine kinase.
The ablation of VEGFR1 by chemical and genetic means has also recently been found to augment the conversion of white adipose tissue to brown adipose tissue as well as increase brown adipose angiogenesis in mice.
Functional genetic variation in FLT1 (rs9582036) has been found to affect non-small cell lung cancer survival.
# Interactions
FLT1 has been shown to interact with PLCG1 and vascular endothelial growth factor B (VEGF-B). | VEGFR1
Vascular endothelial growth factor receptor 1 is a protein that in humans is encoded by the FLT1 gene.[1]
# Function
Oncogene FLT belongs to the src gene family and is related to oncogene ROS (MIM 165020). Like other members of this family, it shows tyrosine protein kinase activity that is important for the control of cell proliferation and differentiation. The sequence structure of the FLT gene resembles that of the FMS gene (MIM 164770); hence, Yoshida et al. (1987) proposed the name FLT as an acronym for FMS-like tyrosine kinase.[supplied by OMIM][2]
The ablation of VEGFR1 by chemical and genetic means has also recently been found to augment the conversion of white adipose tissue to brown adipose tissue as well as increase brown adipose angiogenesis in mice.[3]
Functional genetic variation in FLT1 (rs9582036) has been found to affect non-small cell lung cancer survival.[4]
# Interactions
FLT1 has been shown to interact with PLCG1[5] and vascular endothelial growth factor B (VEGF-B).[6][7] | https://www.wikidoc.org/index.php/VEGFR1 | |
c056bed86c270695ac1e1ded2c324c927c3ceecc | wikidoc | VKORC1 | VKORC1
The human gene VKORC1 encodes for the enzyme, Vitamin K epOxide Reductase Complex (VKORC) subunit 1. This enzymatic protein complex is responsible for reducing vitamin K 2,3-epoxide to its active form, which is important for effective clotting. In humans, mutations in this gene can be associated with deficiencies in vitamin-K-dependent clotting factors.
# Function
The VKORC1 protein is a key enzyme in the vitamin K cycle. VKORC1 is a 163 amino acid integral membrane protein associated with the endoplasmic reticulum and VKORC1 mRNA is broadly expressed in many different tissues. VKORC1 is involved in the vitamin K cycle by reduction of vitamin K epoxide to vitamin K, which is the rate-limiting step in the physiological process of vitamin K recycling. The availability of reduced vitamin K is of importance for activation vitamin K 2,3-epoxide. The reduction of vitamin K epoxide is then responsible for the carboxylation of glutamic acid residues in some blood-clotting proteins, including factor VII, factor IX, and factor X. VKORC1 is of therapeutic interest both for its role in contributing to high interpatient variability in coumarin anticoagulant dose requirements and as a potential player in vitamin K deficiency disorders.
Warfarin is a commonly prescribed oral anticoagulant, or blood thinner used to treat blood clots such as deep vein thrombosis and pulmonary embolism and to prevent stroke in people who have atrial fibrillation, valvular heart disease or artificial heart valves. Warfarin causes inhibition on VKORC1 activities and leads to a reduced amount of vitamin K available to serve as a cofactor for clotting proteins. Inappropriate dosing of warfarin has been associated with a substantial risk of both major and minor hemorrhage. As the pharmacological target of warfarin, VKORC1 is considered a candidate gene for the variability in warfarin response. Previous researches have shown that the CYP2C9 genotype of patients also played a role in warfarin metabolism and response.
# Gene
The human gene is located on chromosome 16. Two pseudogenes have been identified on chromosome 1 and the X chromosome.
# Clinical relevance
In humans, mutations in this gene are associated with deficiencies in vitamin-K-dependent clotting factors. Fatal bleeding (internal) and hemorrhage can result from a decreased ability to form clots.
The product of the VKORC1 gene encodes a subunit of the enzyme that is responsible for reducing vitamin K 2,3-epoxide to the activated form, a reduction reaction. A genetic polymorphism on the VKORC1 gene results in a patient having less available VKORC enzyme to complete this reaction.
Specifically, in the VKORC1 1639 (or 3673) single-nucleotide polymorphism, the common ("wild-type") G allele is replaced by the A allele. People with an A allele (or the "A haplotype") produce less VKORC1 than do those with the G allele (or the "non-A haplotype"). The prevalence of these variants also varies by race, with 90%-95% of Asians, 37% of Caucasians and 14% of Africans carrying the A allele. The end result is a decreased amount of clotting factors and therefore, a decreased ability to clot.
Warfarin is an anticoagulant that opposes the procoagulant effect of vitamin K by inhibiting the VKORC enzyme. If these patients are prescribed warfarin for another medical purpose, they will require lower doses than usual because the patient is already deficient in VKORC. They may experience severe bleeding and bruising. Lower warfarin doses are needed to inhibit VKORC1 and to produce an anticoagulant effect in carriers of the A allele. Genetic testing can reveal the presence of the genetic mutation and FDA recommends lower starting doses of warfarin in these patients.
Two alternatively spliced transcripts encoding different isoforms have also been described. These isoforms result in warfarin resistance (requiring higher doses) in humans and rats, because the amount and effectiveness of the VKORC enzyme has not changed, but the ability of warfarin to exert its effect (antagonize the enzyme) has changed. These isoform mutations are rare except in Ethiopian and certain Jewish populations. | VKORC1
The human gene VKORC1 encodes for the enzyme, Vitamin K epOxide Reductase Complex (VKORC) subunit 1.[1] This enzymatic protein complex is responsible for reducing vitamin K 2,3-epoxide to its active form, which is important for effective clotting. In humans, mutations in this gene can be associated with deficiencies in vitamin-K-dependent clotting factors.
# Function
The VKORC1 protein is a key enzyme in the vitamin K cycle. VKORC1 is a 163 amino acid integral membrane protein associated with the endoplasmic reticulum and VKORC1 mRNA is broadly expressed in many different tissues. VKORC1 is involved in the vitamin K cycle by reduction of vitamin K epoxide to vitamin K, which is the rate-limiting step in the physiological process of vitamin K recycling.[2] The availability of reduced vitamin K is of importance for activation vitamin K 2,3-epoxide. The reduction of vitamin K epoxide is then responsible for the carboxylation of glutamic acid residues in some blood-clotting proteins, including factor VII, factor IX, and factor X.[1][3] VKORC1 is of therapeutic interest both for its role in contributing to high interpatient variability in coumarin anticoagulant dose requirements and as a potential player in vitamin K deficiency disorders.[4]
Warfarin is a commonly prescribed oral anticoagulant, or blood thinner used to treat blood clots such as deep vein thrombosis and pulmonary embolism and to prevent stroke in people who have atrial fibrillation, valvular heart disease or artificial heart valves.[5] Warfarin causes inhibition on VKORC1 activities and leads to a reduced amount of vitamin K available to serve as a cofactor for clotting proteins.[4] Inappropriate dosing of warfarin has been associated with a substantial risk of both major and minor hemorrhage. As the pharmacological target of warfarin, VKORC1 is considered a candidate gene for the variability in warfarin response. Previous researches have shown that the CYP2C9 genotype of patients also played a role in warfarin metabolism and response.[6]
# Gene
The human gene is located on chromosome 16. Two pseudogenes have been identified on chromosome 1 and the X chromosome.
# Clinical relevance
In humans, mutations in this gene are associated with deficiencies in vitamin-K-dependent clotting factors. Fatal bleeding (internal) and hemorrhage can result from a decreased ability to form clots.
The product of the VKORC1 gene encodes a subunit of the enzyme that is responsible for reducing vitamin K 2,3-epoxide to the activated form, a reduction reaction. A genetic polymorphism on the VKORC1 gene results in a patient having less available VKORC enzyme to complete this reaction.
Specifically, in the VKORC1 1639 (or 3673) single-nucleotide polymorphism, the common ("wild-type") G allele is replaced by the A allele. People with an A allele (or the "A haplotype") produce less VKORC1 than do those with the G allele (or the "non-A haplotype"). The prevalence of these variants also varies by race, with 90%-95% of Asians, 37% of Caucasians and 14% of Africans carrying the A allele.[7] The end result is a decreased amount of clotting factors and therefore, a decreased ability to clot.[8]
Warfarin is an anticoagulant that opposes the procoagulant effect of vitamin K by inhibiting the VKORC enzyme. If these patients are prescribed warfarin for another medical purpose, they will require lower doses than usual because the patient is already deficient in VKORC. They may experience severe bleeding and bruising. Lower warfarin doses are needed to inhibit VKORC1 and to produce an anticoagulant effect in carriers of the A allele. Genetic testing can reveal the presence of the genetic mutation and FDA recommends lower starting doses of warfarin in these patients.
Two alternatively spliced transcripts encoding different isoforms have also been described. These isoforms result in warfarin resistance (requiring higher doses) in humans and rats, because the amount and effectiveness of the VKORC enzyme has not changed, but the ability of warfarin to exert its effect (antagonize the enzyme) has changed. These isoform mutations are rare except in Ethiopian and certain Jewish populations. | https://www.wikidoc.org/index.php/VKORC1 | |
ef08444e01d7c43efcf54f31774a7d6bb154528f | wikidoc | VPS13A | VPS13A
Vacuolar protein sorting-associated protein 13A is a protein that in humans is encoded by the VPS13A gene.
# Function
The protein encoded by this gene may control steps in the cycling of proteins through the trans-Golgi network to endosomes, lysosomes and the plasma membrane. Mutations in this gene cause the autosomal recessive disorder, chorea acanthocytosis. Alternative splicing of this gene results in multiple transcript variants.
# Model organisms
Model organisms have been used in the study of VPS13A function. A conditional knockout mouse line called Vps13atm1b(EUCOMM)Wtsi was generated at the Wellcome Trust Sanger Institute. Male and female animals underwent a standardized phenotypic screen to determine the effects of deletion. Additional screens performed: - In-depth immunological phenotyping | VPS13A
Vacuolar protein sorting-associated protein 13A is a protein that in humans is encoded by the VPS13A gene.[1][2][3]
# Function
The protein encoded by this gene may control steps in the cycling of proteins through the trans-Golgi network to endosomes, lysosomes and the plasma membrane. Mutations in this gene cause the autosomal recessive disorder, chorea acanthocytosis. Alternative splicing of this gene results in multiple transcript variants.[3]
# Model organisms
Model organisms have been used in the study of VPS13A function. A conditional knockout mouse line called Vps13atm1b(EUCOMM)Wtsi was generated at the Wellcome Trust Sanger Institute.[4] Male and female animals underwent a standardized phenotypic screen[5] to determine the effects of deletion.[6][7][8][9] Additional screens performed: - In-depth immunological phenotyping[10] | https://www.wikidoc.org/index.php/VPS13A | |
fe9da8d33ca8fe73ac9664c622ab1bd7e0b038b6 | wikidoc | VPS26A | VPS26A
Vacuolar protein sorting-associated protein 26A is a protein that in humans is encoded by the VPS26A gene.
This gene belongs to a group of vacuolar protein sorting (VPS) genes. The encoded protein is a component of a large multimeric complex, termed the retromer complex, involved in retrograde transport of proteins from endosomes to the trans-Golgi network. The close structural similarity between the yeast and human proteins that make up this complex suggests a similarity in function. Expression studies in yeast and mammalian cells indicate that this protein interacts directly with VPS35, which serves as the core of the retromer complex. Alternative splicing results in multiple transcript variants encoding different isoforms.
# Structure
Vps26 is a 38-kDa subunit that has a two-lobed structure with a polar core that resembles the arrestin family of trafficking adaptor. This fold consist of two related β-sandwich subdomains with a fibronectin type III domain topology. The two domains are joined together by a flexible linker and are closely associated by an unusual polar core. Arrestins are regulatory proteins known for connecting G-protein coupled receptors (GPCRs) to clathrin during endocytosis. They play many critical roles in cell signalling and membrane trafficking. Both Vps26 and arrestins are composed of two structurally related β-sheet domains forming extensive interfaces with each other, using polar and electrostatic contacts to create interdomain interactions for ligand binding. However, there are significant structural differences between both Vps26 and arrestins. Vps26 protein has extended C-terminal tails that do not contain identifiable clathrin- or AP2-binding sequences, and therefore cannot form stable intramolecular contacts with clathrin and AP2, which has been observed for arrestins. Moreover, Vps26 does not have similar sequences as arrestins for GPCR and phospholipid interactions.
# Vps26B paralogue
In yeast, there is only one Vps26 species, whereas there are two Vps26 paralogues (Vps26A and Vps26B) in mammals.
X-ray crystallography revealed that the structures of both Vps26A and Vps26B share a similar bilobal β-sandwich structure and possess 70% sequence homology. However, these two paralogues distinctly differ on the surface patch within the N-terminal domain, the apex region where the N-terminal and C-terminal domains meet and the disordered C-terminal tail. Vps26B contains several putative serine phosphorylation residues within this disordered tail, which may represent a potential mechanism to modulate the difference between Vps26A and Vps26B. A recent study conducted by Bugarcic et al. pinpointed that this disordered tail on C-terminal region of Vps26B is one of the underlying factors that contributes to the failure for Vps26B-containing Retromer to associate with CI-M6PR, ultimately leading to CI-M6PR degradation, accompanied with increased cathepsin D secretion. | VPS26A
Vacuolar protein sorting-associated protein 26A is a protein that in humans is encoded by the VPS26A gene.[1][2][3]
This gene belongs to a group of vacuolar protein sorting (VPS) genes. The encoded protein is a component of a large multimeric complex, termed the retromer complex, involved in retrograde transport of proteins from endosomes to the trans-Golgi network. The close structural similarity between the yeast and human proteins that make up this complex suggests a similarity in function. Expression studies in yeast and mammalian cells indicate that this protein interacts directly with VPS35, which serves as the core of the retromer complex. Alternative splicing results in multiple transcript variants encoding different isoforms.[3]
# Structure
Vps26 is a 38-kDa subunit that has a two-lobed structure with a polar core that resembles the arrestin family of trafficking adaptor.[4][5] This fold consist of two related β-sandwich subdomains with a fibronectin type III domain topology. The two domains are joined together by a flexible linker and are closely associated by an unusual polar core. Arrestins are regulatory proteins known for connecting G-protein coupled receptors (GPCRs) to clathrin during endocytosis. They play many critical roles in cell signalling and membrane trafficking.[6] Both Vps26 and arrestins are composed of two structurally related β-sheet domains forming extensive interfaces with each other, using polar and electrostatic contacts to create interdomain interactions for ligand binding. However, there are significant structural differences between both Vps26 and arrestins. Vps26 protein has extended C-terminal tails that do not contain identifiable clathrin- or AP2-binding sequences, and therefore cannot form stable intramolecular contacts with clathrin and AP2, which has been observed for arrestins. Moreover, Vps26 does not have similar sequences as arrestins for GPCR and phospholipid interactions.[7]
# Vps26B paralogue
In yeast, there is only one Vps26 species, whereas there are two Vps26 paralogues (Vps26A and Vps26B) in mammals.[8]
X-ray crystallography revealed that the structures of both Vps26A and Vps26B share a similar bilobal β-sandwich structure and possess 70% sequence homology.[4] However, these two paralogues distinctly differ on the surface patch within the N-terminal domain, the apex region where the N-terminal and C-terminal domains meet and the disordered C-terminal tail. Vps26B contains several putative serine phosphorylation residues within this disordered tail, which may represent a potential mechanism to modulate the difference between Vps26A and Vps26B. A recent study conducted by Bugarcic et al. pinpointed that this disordered tail on C-terminal region of Vps26B is one of the underlying factors that contributes to the failure for Vps26B-containing Retromer to associate with CI-M6PR, ultimately leading to CI-M6PR degradation, accompanied with increased cathepsin D secretion.[9] | https://www.wikidoc.org/index.php/VPS26A | |
0d6b8d7995e4a08b768d323c62c59828bf02af0f | wikidoc | VPS33B | VPS33B
Vacuolar protein sorting-associated protein 33B is a protein that in humans is encoded by the VPS33B gene.
# Function
Vesicle mediated protein sorting plays an important role in segregation of intracellular molecules into distinct organelles. Genetic studies in yeast have identified more than 40 vacuolar protein sorting (VPS) genes involved in vesicle transport to vacuoles. This gene is a member of the Sec-1 domain family, and encodes the human ortholog of rat Vps33b which is homologous to the yeast class C Vps33 protein. The mammalian class C Vps proteins are predominantly associated with late endosomes/lysosomes, and like their yeast counterparts, may mediate vesicle trafficking steps in the endosome/lysosome pathway.
# Model organisms
Model organisms have been used in the study of VPS33B function. A conditional knockout mouse line called Vps33btm1a(EUCOMM)Wtsi was generated at the Wellcome Trust Sanger Institute. Male and female animals underwent a standardized phenotypic screen to determine the effects of deletion. Additional screens performed: In-depth immunological phenotyping | VPS33B
Vacuolar protein sorting-associated protein 33B is a protein that in humans is encoded by the VPS33B gene.[1][2]
# Function
Vesicle mediated protein sorting plays an important role in segregation of intracellular molecules into distinct organelles. Genetic studies in yeast have identified more than 40 vacuolar protein sorting (VPS) genes involved in vesicle transport to vacuoles. This gene is a member of the Sec-1 domain family, and encodes the human ortholog of rat Vps33b which is homologous to the yeast class C Vps33 protein. The mammalian class C Vps proteins are predominantly associated with late endosomes/lysosomes, and like their yeast counterparts, may mediate vesicle trafficking steps in the endosome/lysosome pathway.[2]
# Model organisms
Model organisms have been used in the study of VPS33B function. A conditional knockout mouse line called Vps33btm1a(EUCOMM)Wtsi was generated at the Wellcome Trust Sanger Institute.[3] Male and female animals underwent a standardized phenotypic screen[4] to determine the effects of deletion.[5][6][7][8] Additional screens performed: In-depth immunological phenotyping[9] | https://www.wikidoc.org/index.php/VPS33B | |
a792fc59d3ff92256bba312fa05cdb91c3b87d53 | wikidoc | Vector | Vector
# Overview
In epidemiology, a vector is an organism that does not cause disease itself but which transmits infection by conveying pathogens from one host to another.
A classic example is the anopheles mosquito which acts as a vector for the disease malaria by transmitting the malarial parasite plasmodium to humans.
In this case plasmodium is harmless to the mosquito (its intermediate host) but causes the disease malaria in humans (its definitive host).
In molecular biology and genetic engineering a vector is a vehicle for transferring genetic material into a cell.
A viral vector is a virus which has been modified to transduct specific genetic material into a cell, e.g. for gene therapy.
A plasmid vector is made by splicing a DNA construct into a plasmid. Various techniques are then used to transfect the plasmid into the cell.
# Epidemiology
There are two types of vector that convey infectious organisms to a host: mechanical and biological. Microbes do not multiply within mechanical vectors - mechanical vectors only physically transport microbes from host to host. In contrast, microbes must propagate within a biological vector before the biological vector can transmit the microbes.
- mosquito (malaria, St. Louis encephalitis, dengue fever, yellow fever, West Nile virus)
- flea (bubonic plague)
- tick (Lyme disease, rocky mountain spotted fever, tick-borne encephalitis)
- deer mouse (hantavirus)
- kissing bug (Triatominae) (Chagas Disease)
- bat (Rabies)
# Molecular biology
## Cell transformation and gene therapy
- adenovirus
- adeno-associated virus
- tobacco mosaic virus (plants)
- cytomegalovirus
- bacteriophage (bacteria)
- viral vector
## DNA
- SV40 (Simian virus 40)
- Plasmid
- Yeast artificial chromosome (Chromosome walking, Positional cloning)
- Bacterial artificial chromosome (Shotgun sequencing) | Vector
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
# Overview
In epidemiology, a vector is an organism that does not cause disease itself but which transmits infection by conveying pathogens from one host to another.
A classic example is the anopheles mosquito which acts as a vector for the disease malaria by transmitting the malarial parasite plasmodium to humans.
In this case plasmodium is harmless to the mosquito (its intermediate host) but causes the disease malaria in humans (its definitive host).
In molecular biology and genetic engineering a vector is a vehicle for transferring genetic material into a cell.
A viral vector is a virus which has been modified to transduct specific genetic material into a cell, e.g. for gene therapy.
A plasmid vector is made by splicing a DNA construct into a plasmid. Various techniques are then used to transfect the plasmid into the cell.
# Epidemiology
There are two types of vector that convey infectious organisms to a host: mechanical and biological. Microbes do not multiply within mechanical vectors - mechanical vectors only physically transport microbes from host to host. In contrast, microbes must propagate within a biological vector before the biological vector can transmit the microbes.
- mosquito (malaria, St. Louis encephalitis, dengue fever, yellow fever, West Nile virus)
- flea (bubonic plague)
- tick (Lyme disease, rocky mountain spotted fever, tick-borne encephalitis)
- deer mouse (hantavirus)
- kissing bug (Triatominae) (Chagas Disease)
- bat (Rabies)
# Molecular biology
## Cell transformation and gene therapy
- adenovirus
- adeno-associated virus
- tobacco mosaic virus (plants)
- cytomegalovirus
- bacteriophage (bacteria)
- viral vector
## DNA
- SV40 (Simian virus 40)
- Plasmid
- Yeast artificial chromosome (Chromosome walking, Positional cloning)
- Bacterial artificial chromosome (Shotgun sequencing) | https://www.wikidoc.org/index.php/Vector | |
767655ff0a428ece8e7b8ee90fb1ea04b7993382 | wikidoc | Vibrio | Vibrio
Vibrio is a genus of Gram-negative bacteria possessing a curved rod shape. Typically found in saltwater, Vibrio are facultative anaerobes that test positive for oxidase and do not form spores. All members of the genus are motile and have polar flagella with sheath. Recent phylogenies have been constructed based on a suite of genes (multi-locus sequence analysis).
# Pathogenic strains
Several species of Vibrio include clinically important human pathogens. Most disease causing strains are associated with gastroenteritis but can also infect open wounds and cause septicemia. It can be carried by numerous sea living animals, such as crabs or prawns, and has been known to cause fatal infections in humans during exposure. Pathogenic Vibrio include V. cholerae (the causative agent of cholera), V. parahaemolyticus, and V. vulnificus. Vibrio cholerae is generally transmitted via contaminated water. Pathogenic Vibrio are can cause food poisoning, usually associated with eating undercooked seafood.
Vibrio vulnificus outbreaks commonly occur in warm climates and small, generally lethal, outbreaks occur regularly. An outbreak occurred in New Orleans after Hurricane Katrina and several lethal cases occur most years in Florida.
V. parahaemolyticus is also associated with the Kanagawa phenomenon, in which strains isolated from human hosts (clinical isolates) are hemolytic on blood agar plates, while those isolated from non-human sources are non-hemolytic.
Many Vibrio are also zoonotic. They cause disease in fish and shellfish, and are common causes of mortality among domestic marine life.
# Other strains
Vibrio fischeri, Photobacterium phosphoreum, and V. harveyi are notable for their ability to communicate. Both V. fischeri and Ph. phosphoreum are symbiotes of other marine organisms (typically jellyfish, fish, or squid), and produce light via bioluminescence through the mechanism of quorum sensing. Vibrio harveyi is a pathogen of several aquatic animals and notable as a cause of luminous vibriosis in shrimps (prawns)
# Flagella
The "typical", early-discovered vibrio such as V. cholerae have a single polar flagellum (monotrichous) with sheath. Some species such as V. parahaemolyticus and V. alginolyticus have both a single polar flagellum with sheath and thin flagella projecting in all direction (peritrichous), and the other species such as V. fischeri have tufts of polar flagella with sheath (lophotrichous). | Vibrio
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Vibrio is a genus of Gram-negative bacteria possessing a curved rod shape.[1] [2][3] Typically found in saltwater, Vibrio are facultative anaerobes that test positive for oxidase and do not form spores.[4] All members of the genus are motile and have polar flagella with sheath. Recent phylogenies have been constructed based on a suite of genes (multi-locus sequence analysis).[5]
# Pathogenic strains
Several species of Vibrio include clinically important human pathogens. Most disease causing strains are associated with gastroenteritis but can also infect open wounds and cause septicemia. It can be carried by numerous sea living animals, such as crabs or prawns, and has been known to cause fatal infections in humans during exposure. Pathogenic Vibrio include V. cholerae (the causative agent of cholera), V. parahaemolyticus, and V. vulnificus. Vibrio cholerae is generally transmitted via contaminated water.[3] Pathogenic Vibrio are can cause food poisoning, usually associated with eating undercooked seafood.
Vibrio vulnificus outbreaks commonly occur in warm climates and small, generally lethal, outbreaks occur regularly. An outbreak occurred in New Orleans after Hurricane Katrina [6]and several lethal cases occur most years in Florida.[7]
V. parahaemolyticus is also associated with the Kanagawa phenomenon, in which strains isolated from human hosts (clinical isolates) are hemolytic on blood agar plates, while those isolated from non-human sources are non-hemolytic.[8]
Many Vibrio are also zoonotic. They cause disease in fish and shellfish, and are common causes of mortality among domestic marine life.
# Other strains
Vibrio fischeri, Photobacterium phosphoreum, and V. harveyi are notable for their ability to communicate. Both V. fischeri and Ph. phosphoreum are symbiotes of other marine organisms (typically jellyfish, fish, or squid), and produce light via bioluminescence through the mechanism of quorum sensing. Vibrio harveyi is a pathogen of several aquatic animals and notable as a cause of luminous vibriosis in shrimps (prawns)[9]
# Flagella
The "typical", early-discovered vibrio such as V. cholerae have a single polar flagellum (monotrichous) with sheath. Some species such as V. parahaemolyticus and V. alginolyticus have both a single polar flagellum with sheath and thin flagella projecting in all direction (peritrichous), and the other species such as V. fischeri have tufts of polar flagella with sheath (lophotrichous).[10] | https://www.wikidoc.org/index.php/Vibrio | |
12f11fdabc7dff2a3fd9cfab93f5270b3966f028 | wikidoc | Villus | Villus
# Overview
Villus (Latin: "shaggy hair", plural villi) can refer to:
- Intestinal villus. This is the most common meaning when not more precisely specified
- Chorionic villi, found on the surface of the outermost membrane (the chorion) of the fetus
- Arachnoid villi, located on the arachnoid membrane of the brain | Villus
# Overview
Villus (Latin: "shaggy hair"[1], plural villi) can refer to:
- Intestinal villus. This is the most common meaning when not more precisely specified
- Chorionic villi, found on the surface of the outermost membrane (the chorion) of the fetus
- Arachnoid villi, located on the arachnoid membrane of the brain | https://www.wikidoc.org/index.php/Villi | |
a6862218423ec430bccb0c299e63d692ba959c8b | wikidoc | Villin | Villin
Villin is a 92.5 kDa tissue-specific actin-binding protein associated with the actin core bundle of the brush border. Villin contains multiple gelsolin-like domains capped by a small (8.5 kDa) "headpiece" at the C-terminus consisting of a fast and independently folding three-helix bundle that is stabilized by hydrophobic interactions. The headpiece domain is a commonly studied protein in molecular dynamics due to its small size and fast folding kinetics and short primary sequence.
# Structure
Villin is made up of seven domains, six homologous domains make up the N-terminal core and the remaining domain makes up the C-terminal cap. Villin contains three phosphatidylinositol 4,5-biphosphate (PIP2) binding sites, one of which is located at the head piece and the other two in the core. The core domain is approximately 150 amino acid residues grouped in six repeats. On this core is an 87 residue, hydrophobic, C-terminal headpiece
The headpiece (HP67) is made up of a compact, 70 amino acid folded protein at the C-terminus. This headpiece contains an F-actin binding domain. Residues K38, E39, K65, 70-73:KKEK, G74, L75 and F76 surround a hydrophobic core and are believed to be involved in the binding of F-actin to villin. Residues E39 and K70 form a salt bridge buried within the headpiece which serves to connect N and C terminals. This salt bridge may also orient and fix the C-terminal residues involved in F-actin binding as in the absence of this salt bridge no binding occurs. A hydrophobic “cap” is formed by residue W64 side chains, which is completely conserved throughout the villin family. Below this cap is a crown of alternative positive and negative charged localities.
Villin can undergo post-translational modifications like tyrosine phosphorylation. Villin has the ability to dimerize and the dimerization site is located at the amino end of the protein.
# Expression
Villin is an actin binding protein expressed mainly in the brush border of the epithelium in vertebrates but sometimes it is ubiquitously expressed in protists and plants. Villin is found localized in the microvilli of the brush border of the epithelium lining of the gut and renal tubules in vertebrates.
# Function
Villin is believed to function in the bundling, nucleation, capping and severing of actin filaments. In vertebrates, the villin proteins help to support the microfilaments of the microvilli of the brush border. However, knockout mice appear to show ultra-structurally normal microvilli reminding us that the function of villin is not definitively known; it may play a role in cell plasticity through F-actin severing. The six-repeat villin core is responsible for Ca2+ actin severing while the headpiece is responsible for actin crosslinking and bundling (Ca independent). Villin is postulated to be the controlling protein for Ca2+ induced actin severing in the brush border. Ca2+ inhibits proteolytic cleavage of the domains of the 6 N-terminal core which inhibits actin severing. In normal mice raising Ca2+ levels induces the severing of actin by villin, whereas in villin knockout mice this activity does not occur in response to heightened Ca2+ levels. In the presence of low concentrations of Ca2+ the villin headpiece functions to bundle actin filaments whereas in the presence of high Ca2+ concentrations the N-terminal caps and severs these filaments. The association of PIP2 with villin inhibits the actin capping and severing action and increases actin binding at the headpiece region, possibly through structural changes in the protein. PIP2 increases actin bundling not only by decreasing the severing action of villin but also through dissociating capping proteins, releasing actin monomers from sequestering proteins and stimulating actin nucleation and cross linking.
# Villin subdomain
The C-terminal subdomain of Villin Headpiece VHP67, denoted VHP35, is stabilised in part, by a buried cluster of three phenylalanine residues. Its small size and high helical content are expected to promote rapid folding, and this has been confirmed experimentally.
## Structure
It has a simple topology consisting of three α-helices that form a well-packed hydrophobic core. | Villin
Villin is a 92.5 kDa tissue-specific actin-binding protein associated with the actin core bundle of the brush border.[1] Villin contains multiple gelsolin-like domains capped by a small (8.5 kDa) "headpiece" at the C-terminus consisting of a fast and independently folding three-helix bundle that is stabilized by hydrophobic interactions.[2] The headpiece domain is a commonly studied protein in molecular dynamics due to its small size and fast folding kinetics and short primary sequence.[3][4]
# Structure
Villin is made up of seven domains, six homologous domains make up the N-terminal core and the remaining domain makes up the C-terminal cap.[3] Villin contains three phosphatidylinositol 4,5-biphosphate (PIP2) binding sites, one of which is located at the head piece and the other two in the core.[5] The core domain is approximately 150 amino acid residues grouped in six repeats. On this core is an 87 residue, hydrophobic, C-terminal headpiece[1]
The headpiece (HP67) is made up of a compact, 70 amino acid folded protein at the C-terminus. This headpiece contains an F-actin binding domain. Residues K38, E39, K65, 70-73:KKEK, G74, L75 and F76 surround a hydrophobic core and are believed to be involved in the binding of F-actin to villin. Residues E39 and K70 form a salt bridge buried within the headpiece which serves to connect N and C terminals. This salt bridge may also orient and fix the C-terminal residues involved in F-actin binding as in the absence of this salt bridge no binding occurs. A hydrophobic “cap” is formed by residue W64 side chains, which is completely conserved throughout the villin family. Below this cap is a crown of alternative positive and negative charged localities.[5]
Villin can undergo post-translational modifications like tyrosine phosphorylation.[6] Villin has the ability to dimerize and the dimerization site is located at the amino end of the protein.[7]
# Expression
Villin is an actin binding protein expressed mainly in the brush border of the epithelium in vertebrates but sometimes it is ubiquitously expressed in protists and plants.[4] Villin is found localized in the microvilli of the brush border of the epithelium lining of the gut and renal tubules in vertebrates.[5]
# Function
Villin is believed to function in the bundling, nucleation, capping and severing of actin filaments.[1] In vertebrates, the villin proteins help to support the microfilaments of the microvilli of the brush border. However, knockout mice appear to show ultra-structurally normal microvilli reminding us that the function of villin is not definitively known; it may play a role in cell plasticity through F-actin severing.[5] The six-repeat villin core is responsible for Ca2+ actin severing while the headpiece is responsible for actin crosslinking and bundling (Ca independent). Villin is postulated to be the controlling protein for Ca2+ induced actin severing in the brush border. Ca2+ inhibits proteolytic cleavage of the domains of the 6 N-terminal core which inhibits actin severing.[3] In normal mice raising Ca2+ levels induces the severing of actin by villin, whereas in villin knockout mice this activity does not occur in response to heightened Ca2+ levels.[8] In the presence of low concentrations of Ca2+ the villin headpiece functions to bundle actin filaments whereas in the presence of high Ca2+ concentrations the N-terminal caps and severs these filaments.[1] The association of PIP2 with villin inhibits the actin capping and severing action and increases actin binding at the headpiece region, possibly through structural changes in the protein. PIP2 increases actin bundling not only by decreasing the severing action of villin but also through dissociating capping proteins, releasing actin monomers from sequestering proteins and stimulating actin nucleation and cross linking.[3]
# Villin subdomain
The C-terminal subdomain of Villin Headpiece VHP67, denoted VHP35, is stabilised in part, by a buried cluster of three phenylalanine residues. Its small size and high helical content are expected to promote rapid folding, and this has been confirmed experimentally.
## Structure
It has a simple topology consisting of three α-helices that form a well-packed hydrophobic core. | https://www.wikidoc.org/index.php/Villin | |
e5a1eed3d0d2fb86eadaab13ea5943096f6329ac | wikidoc | Virkon | Virkon
Virkon is a brand name for a powerful, multi-purpose disinfectant. The solution is used in many areas, including hospitals, laboratories, nursing homes, funeral homes, medical, dental and veterinary facilities, and anywhere else where control of pathogens is required. It is typically used for cleaning up hazardous spills, disinfecting surfaces and soaking equipment.
Virkon has a remarkable spectrum of activity against viruses, fungi, spores and bacteria, including mycobacteria such as tuberculosis. It is also effective against SARS and Avian influenza. However, for full effectiveness it must be sprayed liberally on a surface and allowed to sit for at least two (and up to ten) minutes before being wiped off.
# Ingredients
Virkon's ingredients are:
- potassium peroxymonosulfate (21.5%) — disinfecting/cleansing agent
- sulphamic acid — disinfecting/cleansing agent
- malic acid — disinfecting/cleansing agent
- sodium dodecyl benzene sulphonate — detergent
- sodium chloride (1.5%) — disinfecting/cleansing agent
- sodium hexametaphosphate — buffering agent
- Amaranth dye — an indicator colour
- Lemon extract — odorant
The disinfecting agents and detergents work synergistically to attack pathogens.
# Preparation and use
It is most often sold as pink tablets or powder which dissolve readily in water. It is intended to be mixed with water to form a 1% to 3% solution (by weight, i.e. 10g to 30g per litre). The pink colour is useful in that in helps gauge the concentration when preparing the Virkon, and importantly, as the Virkon ages it discolours, making it obvious when it needs to be replaced. The solution is generally stable for five to seven days.
Virkon has a faint lemon odor, but the scent is still considered unpleasant by some. It is relatively safe in terms of skin contact, but can cause eye damage and should not be used as a hand-washing liquid.
When ordered in bulk, Virkon costs about 35 US cents per litre to produce, which is comparable to most bleaches. Nevertheless, some facilities prefer to produce their own alternative disinfectants to save costs.
Virkon is a registered trademark of Antec International, a subsidiary of DuPont. As of 2006, DuPont has been slowly rebranding Virkon as a part of its "RelyOn" disinfectant range. | Virkon
Virkon is a brand name for a powerful, multi-purpose disinfectant. The solution is used in many areas, including hospitals, laboratories, nursing homes, funeral homes, medical, dental and veterinary facilities, and anywhere else where control of pathogens is required. It is typically used for cleaning up hazardous spills, disinfecting surfaces and soaking equipment. [1]
Virkon has a remarkable spectrum of activity against viruses, fungi, spores and bacteria, including mycobacteria such as tuberculosis. It is also effective against SARS[2] and Avian influenza. However, for full effectiveness it must be sprayed liberally on a surface and allowed to sit for at least two (and up to ten) minutes before being wiped off.
# Ingredients
Virkon's ingredients are:
- potassium peroxymonosulfate (21.5%) — disinfecting/cleansing agent
- sulphamic acid — disinfecting/cleansing agent
- malic acid — disinfecting/cleansing agent
- sodium dodecyl benzene sulphonate — detergent
- sodium chloride (1.5%) — disinfecting/cleansing agent
- sodium hexametaphosphate — buffering agent
- Amaranth dye — an indicator colour
- Lemon extract — odorant
The disinfecting agents and detergents work synergistically to attack pathogens.
# Preparation and use
It is most often sold as pink tablets or powder which dissolve readily in water. It is intended to be mixed with water to form a 1% to 3% solution (by weight, i.e. 10g to 30g per litre). The pink colour is useful in that in helps gauge the concentration when preparing the Virkon, and importantly, as the Virkon ages it discolours, making it obvious when it needs to be replaced. The solution is generally stable for five to seven days.
Virkon has a faint lemon odor, but the scent is still considered unpleasant by some. It is relatively safe in terms of skin contact, but can cause eye damage and should not be used as a hand-washing liquid.
When ordered in bulk, Virkon costs about 35 US cents per litre to produce, which is comparable to most bleaches. Nevertheless, some facilities prefer to produce their own alternative disinfectants to save costs.
Virkon is a registered trademark of Antec International, a subsidiary of DuPont. As of 2006, DuPont has been slowly rebranding Virkon as a part of its "RelyOn" disinfectant range. | https://www.wikidoc.org/index.php/Virkon | |
83547c45bfd235cd700306f0dea5f5891f7d0084 | wikidoc | Viscus | Viscus
# Overview
In anatomy, a viscus (plural: viscera) is an internal organ of the thorax or abdomen.
Internal organs are also known as "innards", or less formally, "guts" (which may also refer to the gastrointestinal tract).
The adjective visceral is used for anything pertaining to the internal organs. | Viscus
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
# Overview
In anatomy, a viscus (plural: viscera) is an internal organ of the thorax or abdomen.
Internal organs are also known as "innards", or less formally, "guts" (which may also refer to the gastrointestinal tract).
The adjective visceral is used for anything pertaining to the internal organs. | https://www.wikidoc.org/index.php/Viscera | |
5e51d3a789c151eab2281d4f34d56addd7207ce5 | wikidoc | Visine | Visine
Visine is a brand of eye drops produced by Johnson & Johnson. Johnson & Johnson acquired Visine, along with Pfizer's entire consumer healthcare portfolio, in December 2006.
# Visine Original
The active ingredients in the original Visine formulation are potassium chloride and tetrahydrozoline hydrochloride which is a vasoconstrictor, and therefore constricts the eye's superficial blood vessels to "get the red out", as claimed in Johnson & Johnson's advertising.
## Administration
As with other eye drops, Visine is administered topically with 1 to 2 drops applied to the affected eye(s) up to 4 times daily .
## Adverse effects
- Those using Visine Original frequently report stinging and burning upon application.
- Use can cause a rebound effect causing the redness to worsen. Prolonged use can cause blood vessels to be permanently dilated. Use should be limited.
- A red eye may often be indicative of more serious underlying ocular condition, simply reducing blood flow to the area will not solve the condition and may even exacerbate symptoms
- These drops are also not advised for contact lens wearers as decreased blood flow to the surface of the eye will further lower the levels of oxygen available to the eye. | Visine
Visine is a brand of eye drops produced by Johnson & Johnson. Johnson & Johnson acquired Visine, along with Pfizer's entire consumer healthcare portfolio, in December 2006.
# Visine Original
The active ingredients in the original Visine formulation are potassium chloride and tetrahydrozoline hydrochloride which is a vasoconstrictor, and therefore constricts the eye's superficial blood vessels to "get the red out", as claimed in Johnson & Johnson's advertising[1].
## Administration
As with other eye drops, Visine is administered topically with 1 to 2 drops applied to the affected eye(s) up to 4 times daily [2].
## Adverse effects
- Those using Visine Original frequently report stinging and burning upon application.[1]
- Use can cause a rebound effect causing the redness to worsen. Prolonged use can cause blood vessels to be permanently dilated. Use should be limited.[verification needed]
- A red eye may often be indicative of more serious underlying ocular condition, simply reducing blood flow to the area will not solve the condition and may even exacerbate symptoms
- These drops are also not advised for contact lens wearers as decreased blood flow to the surface of the eye will further lower the levels of oxygen available to the eye. | https://www.wikidoc.org/index.php/Visine | |
e6ec5976b465bf42208c9f08845be78c3a990467 | wikidoc | Vislab | Vislab
The Artificial Vision and Intelligent Systems Laboratory of the University of Parma (also known as Parma VisLab
-r VisLab) is the artificial vision research laboratory of University of Parma, Dipartimento di
Ingegneria dell'Informazione.
It started its activities in 1990, with the involvement of the researchers within the
Eureka PROMETHEUS Project. Since then the research group is focussed on vehicular applications.
VisLab is regarded as one of the leading centers for artificial vision applied to vehicles.
VisLab, directed by Alberto Broggi, undertakes research in basic and applied computer vision; the most
important field of research is the perception of the surrounding environment in vehicular applications using cameras and fusion with other sensors. Its researchers contribute to fields such as artificial vision, image processing, machine learning, neural networks, robotics, and sensor fusion in the vehicular robotics history. Among them, the ARGO Project and the TerraMax Project.
In the eraly years, the research group formed by Alberto Broggi, Massimo Bertozzi and Alessandra Fascioli designed, realized, and successfully tested ARGO.
ARGO was a passenger car able to perceive the environment through the use of microcameras, analyze the surroundings, plan a trajectory, and drive itself on normal roads.
It was tested in 1998 with a 2000+ km tour in Italy, dubbed MilleMiglia in Automatico. In this test the vehicle drove for more than 94% in automatic mode. It was the first test in the world to use off-the-shelf and low cost technology (a Pentiun 200MHz PC and two low-cost video-phone cameras) in normal conditions of traffic, environment, and weather.
Together with Carnegie Mellon's No Hands Across America and Universitat der Bundeswer's test from Munich to Odense, the MilleMiglia in Automatico is regarded as one of the milestones in vehicular robotics.
In 2005 a vehicle called TerraMax was able to successfully conclude the DARPA Grand Challenge; VisLab's vision system was its primary means of perception.
Despite the large vehicle size, the vehicle was able to negotiate different terrains and detect obstacles thanks to an innovative solution based on a trinocular system that was developed by VisLab.
# Location
VisLab is located in the University of Parma main campus, south of Parma, Italy. A new location in Wisconsin, friendly dubbed Vislab America, is
the homebase for projects with VisLab's american partners. | Vislab
The Artificial Vision and Intelligent Systems Laboratory of the University of Parma (also known as Parma VisLab
or VisLab) is the artificial vision research laboratory of University of Parma, Dipartimento di
Ingegneria dell'Informazione.
It started its activities in 1990, with the involvement of the researchers within the
Eureka PROMETHEUS Project. Since then the research group is focussed on vehicular applications.
VisLab is regarded as one of the leading centers for artificial vision applied to vehicles.
VisLab, directed by Alberto Broggi, undertakes research in basic and applied computer vision; the most
important field of research is the perception of the surrounding environment in vehicular applications using cameras and fusion with other sensors[1]. Its researchers contribute to fields such as artificial vision, image processing, machine learning, neural networks, robotics, and sensor fusion in the vehicular robotics history. Among them, the ARGO Project and the TerraMax Project.
In the eraly years, the research group formed by Alberto Broggi, Massimo Bertozzi and Alessandra Fascioli designed, realized, and successfully tested ARGO.
ARGO was a passenger car able to perceive the environment through the use of microcameras, analyze the surroundings, plan a trajectory, and drive itself on normal roads.
It was tested in 1998 with a 2000+ km tour in Italy, dubbed MilleMiglia in Automatico. In this test the vehicle drove for more than 94% in automatic mode. It was the first test in the world to use off-the-shelf and low cost technology (a Pentiun 200MHz PC and two low-cost video-phone cameras) in normal conditions of traffic, environment, and weather.
Together with Carnegie Mellon's No Hands Across America and Universitat der Bundeswer's test from Munich to Odense, the MilleMiglia in Automatico is regarded as one of the milestones in vehicular robotics.
In 2005 a vehicle called TerraMax was able to successfully conclude the DARPA Grand Challenge; VisLab's vision system was its primary means of perception.
Despite the large vehicle size, the vehicle was able to negotiate different terrains and detect obstacles thanks to an innovative solution based on a trinocular system that was developed by VisLab.
# Location
VisLab is located in the University of Parma main campus, south of Parma, Italy. A new location in Wisconsin, friendly dubbed Vislab America, is
the homebase for projects with VisLab's american partners. | https://www.wikidoc.org/index.php/Vislab | |
90fbf5f1a4543f7ecf1a197b39e08d80c9cc4cfe | wikidoc | WNT10A | WNT10A
Wnt-10a is a protein that in humans is encoded by the WNT10A gene.
# Function
The WNT gene family consists of structurally related genes which encode secreted signaling proteins. These proteins have been implicated in oncogenesis and in several developmental processes, including regulation of cell fate and patterning during embryogenesis. This gene is a member of the WNT gene family.
# Clinical significance
WNT10A is strongly expressed in the cell lines of promyelocytic leukemia and Burkitt's lymphoma. In addition, it and another family member, the WNT6 gene, are strongly coexpressed in colorectal cancer cell lines. The gene overexpression may play key roles in carcinogenesis through activation of the WNT-beta-catenin-TCF signaling pathway. This gene and the WNT6 gene are clustered in the chromosome 2q35 region.
Mutations in the WNT10A gene are associated with Schöpf–Schulz–Passarge syndrome and hypodontia. | WNT10A
Wnt-10a is a protein that in humans is encoded by the WNT10A gene.[1][2][3]
# Function
The WNT gene family consists of structurally related genes which encode secreted signaling proteins. These proteins have been implicated in oncogenesis and in several developmental processes, including regulation of cell fate and patterning during embryogenesis. This gene is a member of the WNT gene family.[1]
# Clinical significance
WNT10A is strongly expressed in the cell lines of promyelocytic leukemia and Burkitt's lymphoma. In addition, it and another family member, the WNT6 gene, are strongly coexpressed in colorectal cancer cell lines. The gene overexpression may play key roles in carcinogenesis through activation of the WNT-beta-catenin-TCF signaling pathway. This gene and the WNT6 gene are clustered in the chromosome 2q35 region.[1]
Mutations in the WNT10A gene are associated with Schöpf–Schulz–Passarge syndrome[4] and hypodontia.[5] | https://www.wikidoc.org/index.php/WNT10A | |
d46a50f1ce0c74924c777d4afdd5e05872d31d7e | wikidoc | WP:NPA | WP:NPA
Do not make personal attacks anywhere in Wikipedia. Comment on content, not on the contributor. Personal attacks will not help you make a point; they hurt the Wikipedia community and deter users from helping to create a good encyclopedia.
# What is considered a personal attack?
Debate is an essential part of the culture of Wikipedia. Different contributors often do not agree on some of the content within an article. Contributors often are members of opposing communities who wish to have their viewpoints included in articles. Synthesizing these views into a single article creates a better, more NPOV article for everyone. Every person who edits an article is part of the same larger community - we are all Wikipedians.
Accusing someone without justification of making personal attacks is also considered a form of personal attack.
There is no bright-line rule about what constitutes a personal attack as opposed to constructive discussion, but some types of comments are never acceptable:
- Racial, sexual, homophobic, ageist, religious, political, ethnic, or other epithets (such as against disabled people) directed against another contributor. Disagreement over what constitutes a religion, race, sexual preference, or ethnicity is not a legitimate excuse.
- Using someone's affiliations as a means of dismissing or discrediting their views -- regardless of whether said affiliations are mainstream or extreme.
- Threats of legal action.
- Threats of violence, particularly death threats.
- Threats of vandalism to userpages or talk pages.
- Threats or actions which expose other Wikipedia editors to political, religious or other persecution by government, their employer or any others. Violations of this sort may result in a block for an extended period of time, which may be applied immediately by any administrator upon discovery. Admins applying such sanctions should confidentially notify the members of the Arbitration Committee of what they have done and why.
These examples are not exclusive. Insulting or disparaging an editor is a personal attack regardless of the manner in which it is done. When in doubt, comment on the article's content without referring to its contributor at all.
The prohibition against personal attacks applies equally to all Wikipedians. It is as unacceptable to attack a user with a history of foolish or boorish behavior, or even one who has been subject to disciplinary action by the Arbitration Committee, as it is to attack any other user. Wikipedia encourages a positive online community: people make mistakes, but they are encouraged to learn from them and change their ways. Personal attacks are contrary to this spirit and damaging to the work of building an encyclopedia.
# Responding to personal attacks
## Initial options
Frequently, the best way to respond to an isolated personal attack is not to respond at all. Wikipedia and its debates can become stressful for some editors, who may occasionally overreact. Additionally, Wikipedia discussions are in a text-only medium that conveys nuances and emotions poorly; this can easily lead to misunderstanding. While personal attacks are not excused because of these factors, editors are encouraged to disregard angry and ill-mannered postings of others when it is reasonable to do so, and to continue to focus their efforts on improving and developing the encyclopedia.
If you feel that a response is necessary and desirable, you should leave a polite message on the other user's talk page. Do not respond on a talk page of an article; this tends to escalate matters. Likewise, it is important to avoid becoming hostile and confrontational yourself, even in the face of abuse. Although templates have been used at times for this purpose, a customized message relating to the specific situation is often better received. When possible, try to find compromise or common ground regarding the underlying issues of content, rather than argue about behavior.
Personal attacks do not include civil language used to describe an editor's actions, and when made without involving their personal character, should not be construed as personal attacks, for instance, stating "Your statement is a personal attack..." is not itself a personal attack.
Attacks that are particularly offensive or disruptive (such as physical or legal threats) should not be ignored. Extraordinary situations that require immediate intervention are rare, but may be reported on the administrators' noticeboard.
## Recurring attacks
Recurring, non-disruptive personal attacks that do not stop after reasoned requests to cease should be resolved through the dispute resolution process. Especially when personal attacks arise as the result of heated debate over article content, informal mediation and third-party opinions are often the best ways to resolve the conflict. Similarly, Wikiquette alerts offers a "streamlined" source of outside opinion. In most circumstances, problems with personal attacks can be resolved if editors work together and focus on content, and immediate administrator action is not required.
## Removal of text
There is no official policy regarding when or whether most personal attacks should be removed, although it has been a topic of substantial debate. Removing unquestionable personal attacks from your own user talk page is rarely a matter of concern. On other talk pages, especially where such text is directed against you, removal should typically be limited.
Nevertheless, unusual circumstances do exist. The most serious types of personal attacks, such as efforts to reveal nonpublic personal information about Wikipedia editors, go beyond the level of mere invective, and so can and should be excised for the benefit of the community and the project. In certain cases involving sensitive information, a request for oversight may also be appropriate.
## Off-wiki personal attacks
Wikipedia cannot regulate behavior in media not under the control of the Wikimedia Foundation, but personal attacks made elsewhere create doubt as to whether an editor's on-wiki actions are conducted in good faith. Posting personal attacks or defamation off-Wikipedia is harmful to the community and to an editor's relationship with it, especially when such attacks take the form of violating an editor's privacy. Such attacks can be regarded as aggravating factors by administrators and are admissible evidence in the dispute-resolution process, including Arbitration cases. In some cases, the evidence will be submitted by private email. | WP:NPA
Template:Nutshell
Template:Policylist
Do not make personal attacks anywhere in Wikipedia. Comment on content, not on the contributor. Personal attacks will not help you make a point; they hurt the Wikipedia community and deter users from helping to create a good encyclopedia.
# What is considered a personal attack?
Debate is an essential part of the culture of Wikipedia. Different contributors often do not agree on some of the content within an article. Contributors often are members of opposing communities who wish to have their viewpoints included in articles. Synthesizing these views into a single article creates a better, more NPOV article for everyone. Every person who edits an article is part of the same larger community - we are all Wikipedians.
Accusing someone without justification of making personal attacks is also considered a form of personal attack.
Editors should be civil and adhere to good wiki etiquette when stating disagreements. Comments should not be personalized and should be directed at content and actions rather than people. However, when there are disagreements about content, referring to other editors is not always a personal attack. A posting that says "Your statement about X is wrong because of information at Y", or "The paragraph you inserted into the article looks like original research", is not a personal attack. The appropriate response to such statements is to address the issues of content rather than to accuse the other person of violating this policy.
There is no bright-line rule about what constitutes a personal attack as opposed to constructive discussion, but some types of comments are never acceptable:
- Racial, sexual, homophobic, ageist, religious, political, ethnic, or other epithets (such as against disabled people) directed against another contributor. Disagreement over what constitutes a religion, race, sexual preference, or ethnicity is not a legitimate excuse.
- Using someone's affiliations as a means of dismissing or discrediting their views -- regardless of whether said affiliations are mainstream or extreme.
- Threats of legal action.
- Threats of violence, particularly death threats.
- Threats of vandalism to userpages or talk pages.
- Threats or actions which expose other Wikipedia editors to political, religious or other persecution by government, their employer or any others. Violations of this sort may result in a block for an extended period of time, which may be applied immediately by any administrator upon discovery. Admins applying such sanctions should confidentially notify the members of the Arbitration Committee of what they have done and why.
These examples are not exclusive. Insulting or disparaging an editor is a personal attack regardless of the manner in which it is done. When in doubt, comment on the article's content without referring to its contributor at all.
The prohibition against personal attacks applies equally to all Wikipedians. It is as unacceptable to attack a user with a history of foolish or boorish behavior, or even one who has been subject to disciplinary action by the Arbitration Committee, as it is to attack any other user. Wikipedia encourages a positive online community: people make mistakes, but they are encouraged to learn from them and change their ways. Personal attacks are contrary to this spirit and damaging to the work of building an encyclopedia.
# Responding to personal attacks
## Initial options
Frequently, the best way to respond to an isolated personal attack is not to respond at all. Wikipedia and its debates can become stressful for some editors, who may occasionally overreact. Additionally, Wikipedia discussions are in a text-only medium that conveys nuances and emotions poorly; this can easily lead to misunderstanding. While personal attacks are not excused because of these factors, editors are encouraged to disregard angry and ill-mannered postings of others when it is reasonable to do so, and to continue to focus their efforts on improving and developing the encyclopedia.
If you feel that a response is necessary and desirable, you should leave a polite message on the other user's talk page. Do not respond on a talk page of an article; this tends to escalate matters. Likewise, it is important to avoid becoming hostile and confrontational yourself, even in the face of abuse. Although templates have been used at times for this purpose, a customized message relating to the specific situation is often better received. When possible, try to find compromise or common ground regarding the underlying issues of content, rather than argue about behavior.
Personal attacks do not include civil language used to describe an editor's actions, and when made without involving their personal character, should not be construed as personal attacks, for instance, stating "Your statement is a personal attack..." is not itself a personal attack.
Attacks that are particularly offensive or disruptive (such as physical or legal threats) should not be ignored. Extraordinary situations that require immediate intervention are rare, but may be reported on the administrators' noticeboard.
## Recurring attacks
Recurring, non-disruptive personal attacks that do not stop after reasoned requests to cease should be resolved through the dispute resolution process. Especially when personal attacks arise as the result of heated debate over article content, informal mediation and third-party opinions are often the best ways to resolve the conflict. Similarly, Wikiquette alerts offers a "streamlined" source of outside opinion. In most circumstances, problems with personal attacks can be resolved if editors work together and focus on content, and immediate administrator action is not required.
## Removal of text
There is no official policy regarding when or whether most personal attacks should be removed, although it has been a topic of substantial debate.[1] Removing unquestionable personal attacks from your own user talk page is rarely a matter of concern. On other talk pages, especially where such text is directed against you, removal should typically be limited.
Nevertheless, unusual circumstances do exist. The most serious types of personal attacks, such as efforts to reveal nonpublic personal information about Wikipedia editors, go beyond the level of mere invective, and so can and should be excised for the benefit of the community and the project. In certain cases involving sensitive information, a request for oversight may also be appropriate.
## Off-wiki personal attacks
Wikipedia cannot regulate behavior in media not under the control of the Wikimedia Foundation, but personal attacks made elsewhere create doubt as to whether an editor's on-wiki actions are conducted in good faith. Posting personal attacks or defamation off-Wikipedia is harmful to the community and to an editor's relationship with it, especially when such attacks take the form of violating an editor's privacy. Such attacks can be regarded as aggravating factors by administrators and are admissible evidence in the dispute-resolution process, including Arbitration cases. In some cases, the evidence will be submitted by private email.
### External links
Links or references to off-site harassment, attacks, or privacy violations against Wikipedians are not permitted, and should be removed. Such removals are not subject to the three-revert rule. Attacking, harassing, or violating the privacy of any Wikipedian through the posting of external links is not permitted, and those who do so deliberately or repeatedly may be blocked.[2][3] As with personal attacks, extreme cases of harassment by way of external links can be grounds for banning.
# Consequences of personal attacks
Although editors are encouraged to ignore or respond politely to isolated personal attacks, that should not imply that they are acceptable or without consequences. A pattern of hostility reduces the likelihood of the community assuming good faith, and can be considered disruptive editing. Users who insist on a confrontational style marked by personal attacks are likely to end up in the dispute resolution process, possibly including the serious consequences of arbitration, and may become subject to a community ban.
In extreme cases, even isolated personal attacks may lead to a block for disruption. Legal threats, death threats, and issues of similar severity may result in a block without warning. However, administrators are cautioned that other resolutions are preferable to blocking for less severe situations when it is unclear if the "conduct severely disrupts the project". Recurring attacks are proportionally more likely to be considered "disruption". Blocking for personal attacks should only be done for prevention, not punishment. A block may be warranted if it seems likely that the user will continue using personal attacks. | https://www.wikidoc.org/index.php/WP:NPA | |
9a3c8cc386cca62732c151459ca89876a3bf082e | wikidoc | WRNIP1 | WRNIP1
ATPase WRNIP1 is an enzyme that in humans is encoded by the WRNIP1 gene.
Werner's syndrome is a rare autosomal recessive disorder characterized by premature aging. The protein encoded by this gene interacts with the N-terminal portion of Werner protein containing the exonuclease domain. This protein shows homology to replication factor C family proteins, and is conserved from E. coli to human. Studies in yeast suggest that this gene may influence the aging process. Two transcript variants encoding different isoforms have been isolated for this gene.
# Interactions
WRNIP1 has been shown to interact with Werner syndrome ATP-dependent helicase. | WRNIP1
ATPase WRNIP1 is an enzyme that in humans is encoded by the WRNIP1 gene.[1][2]
Werner's syndrome is a rare autosomal recessive disorder characterized by premature aging. The protein encoded by this gene interacts with the N-terminal portion of Werner protein containing the exonuclease domain. This protein shows homology to replication factor C family proteins, and is conserved from E. coli to human. Studies in yeast suggest that this gene may influence the aging process. Two transcript variants encoding different isoforms have been isolated for this gene.[2]
# Interactions
WRNIP1 has been shown to interact with Werner syndrome ATP-dependent helicase.[1] | https://www.wikidoc.org/index.php/WRNIP1 | |
998c1b2d9d9323b6cfbe546ea50653206ef376ef | wikidoc | Wakame | Wakame
# Health
New studies conducted at Hokkaido University have found that a compound in wakame known as fucoxanthin can help burn fatty tissue. Studies in mice have shown that fucoxanthin induces expression of the fat-burning protein UCP1 that accumulates in fat tissue around the internal organs. Expression of UCP1 protein was significantly increased in mice fed fucoxanthin.
Wakame is also used in topical beauty treatments.
See also Fucoidan
In Oriental medicine it has been used for blood purification, intestinal strength, skin, hair, reproductive organs and menstrual regularity .
# Invasiveness
In New Zealand, wakame is a very serious weed, and was nominated one of the 100 worst invasive species in the world. It was first discovered in Wellington Harbour in 1987. It probably arrived accidentally in the late 1980s, via shipping from Asia, in ballast water. Native to cold temperate coastal areas of Japan, Korea and China, in recent decades it has also established in France, Great Britain, Spain, Italy, Argentina and Australia.
Wakame is now found around much of south-eastern New Zealand, and as far north as Auckland. It spreads in two ways: naturally, through the millions of microscopic spores released by each fertile organism, and through attachment to vessel hulls and marine farming equipment. It is a highly successful and fertile species, which makes it a serious invader. However, its impacts are not well understood and are likely to vary, depending on the location.
# As food
Wakame fronds are green and have a subtly sweet flavour and slippery texture. The leaves should be cut into small pieces as they will expand during cooking.
In Japan, wakame is distributed either dried or salted, and used in soups (particularly miso soup, and salads (Tofu salad), of often simply as a side dish to Tofu and a salad vegetable like cucumber. These dishes are typically dressed with Japanese ingredients including soya sauce and vinegar/rice vinegar.
- In China, it is called qundaicai. Chinese production is concentrated around Dalian.
- In Korea, it is called miyeok and used in salads or soup.
Wakame is a rich source of EPA, an ω-3 essential fatty acid. At over 400 mg/100 kcal or almost 1 mg/kJ, it has one of the higher nutrient:calorie ratios, and among the very highest for a vegetarian source. However, 100 grams of Wakame is more than 44 tablespoons of dried Wakame. The usual consumpton of Wakame is closer to 1 or 2 tablespoons. Wakame also has high levels of calcium, thiamine, niacin, and vitamin B12. | Wakame
Template:Nihongo, Undaria pinnatifida, is a type of edible kelp.
# Health
New studies conducted at Hokkaido University have found that a compound in wakame known as fucoxanthin can help burn fatty tissue. Studies in mice have shown that fucoxanthin induces expression of the fat-burning protein UCP1 that accumulates in fat tissue around the internal organs. Expression of UCP1 protein was significantly increased in mice fed fucoxanthin.
Wakame is also used in topical beauty treatments.
See also Fucoidan
In Oriental medicine it has been used for blood purification, intestinal strength, skin, hair, reproductive organs and menstrual regularity [1].
# Invasiveness
In New Zealand, wakame is a very serious weed, and was nominated one of the 100 worst invasive species in the world. It was first discovered in Wellington Harbour in 1987. It probably arrived accidentally in the late 1980s, via shipping from Asia, in ballast water. Native to cold temperate coastal areas of Japan, Korea and China, in recent decades it has also established in France, Great Britain, Spain, Italy, Argentina and Australia.
Wakame is now found around much of south-eastern New Zealand, and as far north as Auckland. It spreads in two ways: naturally, through the millions of microscopic spores released by each fertile organism, and through attachment to vessel hulls and marine farming equipment. It is a highly successful and fertile species, which makes it a serious invader. However, its impacts are not well understood and are likely to vary, depending on the location.
# As food
Wakame fronds are green and have a subtly sweet flavour and slippery texture. The leaves should be cut into small pieces as they will expand during cooking.
In Japan, wakame is distributed either dried or salted, and used in soups (particularly miso soup, and salads (Tofu salad), of often simply as a side dish to Tofu and a salad vegetable like cucumber. These dishes are typically dressed with Japanese ingredients including soya sauce and vinegar/rice vinegar.
- In China, it is called qundaicai. Chinese production is concentrated around Dalian.
- In Korea, it is called miyeok and used in salads or soup.
Wakame is a rich source of EPA, an ω-3 essential fatty acid. At over 400 mg/100 kcal or almost 1 mg/kJ, it has one of the higher nutrient:calorie ratios, and among the very highest for a vegetarian source. However, 100 grams of Wakame is more than 44 tablespoons of dried Wakame. The usual consumpton of Wakame is closer to 1 or 2 tablespoons.[2] Wakame also has high levels of calcium, thiamine, niacin, and vitamin B12. | https://www.wikidoc.org/index.php/Wakame | |
cf75da035927ad60354dbb90ea81b95fbe103092 | wikidoc | Wasabi | Wasabi
Wasabi (Template:Lang-ja,ワサビ , 山葵 (originally written 和佐比); Wasabia japonica, Cochlearia wasabi, or Eutrema japonica) is a member of the Brassicaceae family, which includes cabbages, horseradish and mustard. Known as "Japanese horseradish", its root is used as a spice and has an extremely strong flavor. Its hotness is more akin to that of a hot mustard than the capsaicin in a chili pepper, producing vapors that irritate the nasal passages more than the tongue. The plant grows naturally along stream beds in mountain river valleys in Japan. There are also other species used, such as W. koreana, and W. tetsuigi. The two main cultivars in the marketplace are W. japonica var. Daruma and Mazuma, but there are many others.
# Uses
Wasabi is generally sold either in the form of a root (real wasabi), which must be very finely grated before use, or as a ready-to-use paste (horseradish, mustard and food coloring), usually in tubes approximately the size and shape of travel toothpaste tubes. Once the paste is prepared it should remain covered until served to protect the flavor from evaporation. For this reason, sushi chefs usually put the wasabi between the fish and the rice.
Fresh leaves of wasabi can also be eaten and have some of the hot flavor of wasabi roots. They can be eaten as wasabi salad by pickling overnight with a salt-and-vinegar-based dressing, or by quickly boiling them with a little soy sauce. Additionally, the leaves can be battered and deep-fried into chips.
The burning sensations it can induce are short-lived compared to the effects of chili peppers, especially when water is used to remove the spicy flavor.
Wasabi is often served with sushi or sashimi, usually accompanied with soy sauce. The two are sometimes mixed to form a single dipping sauce known as Wasabi-joyu. Legumes (or peas) may be roasted or fried, then coated with a wasabi-like mixture (usually an imitation); these are then eaten as an eye-watering "in the hand" snack.
Wasabi ice cream is a recent but increasingly popular innovation.
Recent studies have also shown that wasabi contains a natural chemical that can be used against certain cancer cells. This unique root vegetable can also be used for oral hygiene and infections. It has been suggested that Wasabi can help prevent cardiovascular diseases like stroke, heart attack, and hypertension. The health benefits are many. This root can help with diarrhea, osteoporosis, asthma, arthritis, and allergies as well.
# Wasabi and imitations
Almost all sushi bars in America and Japan serve imitation (seiyō) wasabi (see Etymology section, below) because authentic wasabi is usually expensive, but it is becoming widely available even in the United States. Wasabi loses much of its flavor if exposed to air for even a short time, so genuine powdered wasabi, while it does exist, typically contains horseradish and other ingredients to approximate the nasal spiciness of fresh wasabi. Because of this, most powders use no real wasabi and instead turn to just horseradish, mustard seed, and green food coloring (sometimes Spirulina). Whether real or imitation, the powder is mixed with an equal amount of water to make a paste. Few people, even in Japan, realize that most of the wasabi that they consume is in fact an imitation. While not considered equal with the freshly grated product, preserved wasabi is available in tubes and, in larger quantity, frozen bags. Like powder, tubed wasabi often contains no real wasabi at all, so verification of the ingredients is needed.
To distinguish between the true variety of wasabi and the imitation product, real wasabi is known in Japan as hon-wasabi (本山葵), meaning original or true wasabi. Local Sushi chefs usually substitute horseradish in Japanese restaurants.
# Chemistry
The chemicals in wasabi that provide its unique flavor are the isothiocyanates, including:
- 6-methylthiohexyl isothiocyanate,
- 7-methylthioheptyl isothiocyanate and
- 8-methylthiooctyl isothiocyanate.
Research has shown that isothiocyanates have beneficial effects such as inhibiting microbe growth.
# Cultivation
Few places are suitable for large-scale wasabi cultivation, and cultivation is difficult even in ideal conditions. In Japan, wasabi is cultivated mainly in these regions:
- Izu peninsula, located in Shizuoka prefecture
- Nagano prefecture
- Shimane prefecture
- Yamanashi prefecture
- Iwate prefecture
There are also numerous artificially cultivated facilities as far north as Hokkaidō and as far south as Kyūshū. The demand for real wasabi is very high. Japan has to import a large amount of it from:
- Mainland China,
- Ali Mountain of Taiwan, and
- New Zealand.
In North America, a handful of companies and small farmers are successfully pursuing the trend by cultivating Wasabia japonica. While only the Pacific Northwest and parts of the Blue Ridge Mountains provide the right balance of climate and water for natural cultivation of sawa (water grown) wasabi, the use of hydroponics and greenhouses has extended the range.
- British Columbia, Canada
- North Carolina, United States
While the finest sawa wasabi is grown in pure, constantly flowing water, without pesticides or fertilizers, some growers push growth with fertilizer such as chicken manure, which can be a source of downstream pollution if not properly managed.
# Preparation
Wasabi is often grated with a metal oroshigane, but some prefer to use a more traditional tool made of dried sharkskin (鮫皮) with fine skin on one side and coarse skin on the other. A hand-made grater with irregular teeth can also be used. If a shark-skin grater is unavailable, ceramic is usually preferred.
# Etymology
The two kanji characters "山" and "葵" do not correspond to their pronunciation: as such it is an example of gikun. The two characters actually refer to the mountain hollyhock, as the plant's leaves resemble those of a member of the Malvaceae family, in addition to its ability to grow on shady hillsides. The word, in the form 和佐比, first appeared in 918 in The Japanese Names of Medical Herbs (本草和名 Honzō Wamyō). Spelled in this way, the particular kanji are used for their phonetic values only, known as ateji.
In Japanese, horseradish is known as Template:Nihongo ("Western wasabi").
# Gallery
- Wasabi peas
Wasabi peas
- Wild Wasabi
Wild Wasabi | Wasabi
Wasabi (Template:Lang-ja,ワサビ , 山葵 (originally written 和佐比); Wasabia japonica, Cochlearia wasabi, or Eutrema japonica) is a member of the Brassicaceae family, which includes cabbages, horseradish and mustard. Known as "Japanese horseradish", its root is used as a spice and has an extremely strong flavor. Its hotness is more akin to that of a hot mustard than the capsaicin in a chili pepper, producing vapors that irritate the nasal passages more than the tongue. The plant grows naturally along stream beds in mountain river valleys in Japan. There are also other species used, such as W. koreana, and W. tetsuigi. The two main cultivars in the marketplace are W. japonica var. Daruma and Mazuma, but there are many others.
# Uses
Wasabi is generally sold either in the form of a root (real wasabi), which must be very finely grated before use, or as a ready-to-use paste (horseradish, mustard and food coloring), usually in tubes approximately the size and shape of travel toothpaste tubes. Once the paste is prepared it should remain covered until served to protect the flavor from evaporation. For this reason, sushi chefs usually put the wasabi between the fish and the rice.
Fresh leaves of wasabi can also be eaten and have some of the hot flavor of wasabi roots. They can be eaten as wasabi salad by pickling overnight with a salt-and-vinegar-based dressing, or by quickly boiling them with a little soy sauce. Additionally, the leaves can be battered and deep-fried into chips.
The burning sensations it can induce are short-lived compared to the effects of chili peppers, especially when water is used to remove the spicy flavor.
Wasabi is often served with sushi or sashimi, usually accompanied with soy sauce. The two are sometimes mixed to form a single dipping sauce known as Wasabi-joyu. Legumes (or peas) may be roasted or fried, then coated with a wasabi-like mixture (usually an imitation); these are then eaten as an eye-watering "in the hand" snack.
Wasabi ice cream is a recent but increasingly popular innovation.
Recent studies have also shown that wasabi contains a natural chemical that can be used against certain cancer cells. This unique root vegetable can also be used for oral hygiene and infections. It has been suggested that Wasabi can help prevent cardiovascular diseases like stroke, heart attack, and hypertension. The health benefits are many. This root can help with diarrhea, osteoporosis, asthma, arthritis, and allergies as well.[1]
# Wasabi and imitations
Almost all sushi bars in America and Japan serve imitation (seiyō) wasabi (see Etymology section, below) because authentic wasabi is usually expensive, but it is becoming widely available even in the United States. Wasabi loses much of its flavor if exposed to air for even a short time, so genuine powdered wasabi, while it does exist, typically contains horseradish and other ingredients to approximate the nasal spiciness of fresh wasabi. Because of this, most powders use no real wasabi and instead turn to just horseradish, mustard seed, and green food coloring (sometimes Spirulina). Whether real or imitation, the powder is mixed with an equal amount of water to make a paste. Few people, even in Japan, realize that most of the wasabi that they consume is in fact an imitation. While not considered equal with the freshly grated product, preserved wasabi is available in tubes and, in larger quantity, frozen bags. Like powder, tubed wasabi often contains no real wasabi at all, so verification of the ingredients is needed.
To distinguish between the true variety of wasabi and the imitation product, real wasabi is known in Japan as hon-wasabi (本山葵), meaning original or true wasabi. Local Sushi chefs usually substitute horseradish in Japanese restaurants.
# Chemistry
The chemicals in wasabi that provide its unique flavor are the isothiocyanates, including:
- 6-methylthiohexyl isothiocyanate,
- 7-methylthioheptyl isothiocyanate and
- 8-methylthiooctyl isothiocyanate.
Research has shown that isothiocyanates have beneficial effects such as inhibiting microbe growth.
# Cultivation
Few places are suitable for large-scale wasabi cultivation, and cultivation is difficult even in ideal conditions. In Japan, wasabi is cultivated mainly in these regions:
- Izu peninsula, located in Shizuoka prefecture
- Nagano prefecture
- Shimane prefecture
- Yamanashi prefecture
- Iwate prefecture
There are also numerous artificially cultivated facilities as far north as Hokkaidō and as far south as Kyūshū. The demand for real wasabi is very high. Japan has to import a large amount of it from:
- Mainland China,
- Ali Mountain of Taiwan, and
- New Zealand.
In North America, a handful of companies and small farmers are successfully pursuing the trend by cultivating Wasabia japonica. While only the Pacific Northwest and parts of the Blue Ridge Mountains provide the right balance of climate and water for natural cultivation of sawa (water grown) wasabi, the use of hydroponics and greenhouses has extended the range.
- British Columbia, Canada
- North Carolina, United States
While the finest sawa wasabi is grown in pure, constantly flowing water, without pesticides or fertilizers, some growers push growth with fertilizer such as chicken manure, which can be a source of downstream pollution if not properly managed.
# Preparation
Wasabi is often grated with a metal oroshigane, but some prefer to use a more traditional tool made of dried sharkskin (鮫皮) with fine skin on one side and coarse skin on the other. A hand-made grater with irregular teeth can also be used. If a shark-skin grater is unavailable, ceramic is usually preferred.
# Etymology
The two kanji characters "山" and "葵" do not correspond to their pronunciation: as such it is an example of gikun. The two characters actually refer to the mountain hollyhock, as the plant's leaves resemble those of a member of the Malvaceae family, in addition to its ability to grow on shady hillsides. The word, in the form 和佐比, first appeared in 918 in The Japanese Names of Medical Herbs (本草和名 Honzō Wamyō). Spelled in this way, the particular kanji are used for their phonetic values only, known as ateji.
In Japanese, horseradish is known as Template:Nihongo ("Western wasabi").
# Gallery
- Wasabi peas
Wasabi peas
- Wild Wasabi
Wild Wasabi | https://www.wikidoc.org/index.php/Wasabi | |
92b7e599395c7576a57cd6ede3255db94e7c7a16 | wikidoc | Weight | Weight
In the physical sciences, weight is a measurement of the gravitational force acting on an object. Near the surface of the Earth, the acceleration due to gravity is approximately constant; this means that an object's weight is roughly proportional to its mass. The words "weight" and "mass" are therefore often used interchangeably, even though they do not describe the same concept.
# Weight and mass
In modern usage in the field of mechanics, weight and mass are fundamentally different quantities: mass is an intrinsic property of matter, whereas weight is a force that results from the action of gravity on matter.
However, the recognition of this difference is, historically, a relatively recent development – and in many everyday situations the word "weight" continues to be used when strictly speaking "mass" is meant. For example, we say that an object "weighs one kilogram", even though the kilogram is actually a unit of mass. This common usage is due to the displacement of earlier force-based measurement systems by the more scientific mass-based SI system. This transition has led to the common and even legal intertwining of "weight" and "mass."
The distinction between mass and weight is unimportant for many practical purposes because, to a reasonable approximation, the strength of gravity is the same everywhere on the surface of the Earth. In such a constant gravitational field, the gravitational force exerted on an object (its weight) is directly proportional to its mass. So, if object A weighs, say, 10 times as much as object B, then object A's mass is 10 times that of object B. This means that an object's mass can be measured indirectly by its weight (for conversion formulas see below). For example, when we buy a bag of sugar we can measure its weight (how hard it presses down on the scales) and be sure that this will give a good indication of the quantity that we are actually interested in, which is the mass of sugar in the bag. Nevertheless, slight variations in the Earth's gravitational field do exist (see Earth's gravity), and these must be taken into account in high precision weight measurements.
The use of "weight" for "mass" also persists in some scientific terminology – for example, in the chemical terms "atomic weight", "molecular weight", and "formula weight", rather than the preferred "atomic mass" etc.
The difference between mass and force becomes obvious when:
- objects are compared in different gravitational fields, such as away from the Earth's surface. For example, on the surface of the Moon, gravity is only about one-sixth as strong as on the surface of the Earth. A one-kilogram mass is still a one-kilogram mass (as mass is an intrinsic property of the object) but the downwards force due to gravity is only one-sixth of what the object would experience on Earth.
- masses are considered in the context of a lever, such as a cantilever structure.
- locating the center of gravity of an object.
# Units of weight (force)
Systems of units of weight (force) and mass have a tangled history, partly because the distinction was not properly understood when many of the units first came into use.
## SI units
In most modern scientific work, physical quantities are measured in SI units. The SI unit of mass is the kilogram. The SI unit of force (and hence weight) is the newton (N) – which can also be expressed in SI base units as kg·m/s² (kilograms times meters per second squared).
The kilogram-force is a non-SI unit of force, defined as the force exerted by a one-kilogram mass in standard Earth gravity (equal to about 9.8 newtons).
The gravitational force exerted on an object is proportional to the mass of the object, so it is reasonable to think of the strength of gravity as measured in terms of force per unit mass, that is, newtons per kilogram (N/kg). However, the unit N/kg resolves to m/s²; (metres per second per second), which is the SI unit of acceleration, and in practice gravitational strength is usually quoted as an acceleration.
## The pound and related units
In United States customary units, the pound can be either a unit of force or a unit of mass. Related units used in some distinct, separate subsystems of units include the poundal and the slug. The poundal is defined as the force necessary to accelerate a one-pound object at 1 ft/s², and is equivalent to about 1/32 of a pound (force). The slug is defined as the amount of mass that accelerates at 1 ft/s² when a pound of force is exerted on it, and is equivalent to about 32 pounds (mass).
## Conversion between weight (force) and mass
To convert between weight (force) and mass we use Newton's second law, F = ma (force = mass × acceleration). Here, F is the force due to gravity (i.e. the weight force), m is the mass of the object in question, and a is the acceleration due to gravity, on Earth approximately 9.8 m/s² or 32 ft/s²). In this context the same equation is often written as W = mg, with W standing for weight, and g for the acceleration due to gravity.
# Sensation of weight
The weight force that we actually sense is not the downward force of gravity, but the normal force (an upward contact force) exerted by the surface we stand on, which opposes gravity and prevents us falling to the center of the Earth. This normal force, called the apparent weight, is the one that is measured by a spring scale.
For a body supported in a stationary position, the normal force balances the earth's gravitational force, and so apparent weight has the same magnitude as actual weight. (Technically, things are slightly more complicated. For example, an object immersed in water weighs less, according to a spring scale, than the same object in air; this is due to buoyancy, which opposes the weight force and therefore generates a smaller normal. These and other factors are explained further under apparent weight.)
If there is no contact with any surface to provide such an opposing force then there is no sensation of weight (no apparent weight). This happens in free-fall, as experienced by sky-divers (until they approach terminal velocity) and astronauts in orbit, who feel "weightless" even though their bodies are still subject to the force of gravity: they're just no longer resisting it. The experience of having no apparent weight is also known as microgravity.
A degree of reduction of apparent weight occurs, for example, in elevators. In an elevator, a spring scale will register a decrease in a person's (apparent) weight as the elevator starts to accelerate downwards. This is because the opposing force of the elevator's floor decreases as it accelerates away underneath one's feet.
# Measuring weight
Weight is commonly measured using one of two methods. A spring scale or hydraulic or pneumatic scale measures weight force (strictly apparent weight force) directly. If the intention is to measure mass rather than weight, then this force must be converted to mass. As explained above, this calculation depends on the strength of gravity. Household and other low precision scales that are calibrated in units of mass (such as kilograms) assume roughly that standard gravity will apply. However, although nearly constant, the apparent or actual strength of gravity does in fact vary very slightly in different places on the earth (see standard gravity, physical geodesy, gravity anomaly and gravity). This means that same object (the same mass) will exert a slightly different weight force in different places. High precision spring scales intended to measure mass must therefore be calibrated specifically according their location on earth.
Mass may also be measured with a balance, which compares the item in question to others of known mass. This comparison remains valid whatever the local strength of gravity. If weight force, rather than mass, is required, then this can be calculated by multiplying mass by the acceleration due to gravity – either standard gravity (for everyday work) or the precise local gravity (for precision work).
Gross weight is a term that generally is found in commerce or trade applications, and refers to the gross or total weight of a product and its packaging. Conversely, net weight refers to the intrinsic weight of the product itself, discounting the weight of packaging or other materials.
# Relative weights on the Earth, other planets and the Moon
The following is a list of the weights of a mass on the surface of some of the bodies in the solar system, relative to its weight on Earth: | Weight
In the physical sciences, weight is a measurement of the gravitational force acting on an object. Near the surface of the Earth, the acceleration due to gravity is approximately constant; this means that an object's weight is roughly proportional to its mass. The words "weight" and "mass" are therefore often used interchangeably, even though they do not describe the same concept.
# Weight and mass
In modern usage in the field of mechanics, weight and mass are fundamentally different quantities: mass is an intrinsic property of matter, whereas weight is a force that results from the action of gravity on matter.
However, the recognition of this difference is, historically, a relatively recent development – and in many everyday situations the word "weight" continues to be used when strictly speaking "mass" is meant. For example, we say that an object "weighs one kilogram", even though the kilogram is actually a unit of mass. This common usage is due to the displacement of earlier force-based measurement systems by the more scientific mass-based SI system. This transition has led to the common and even legal intertwining of "weight" and "mass."
The distinction between mass and weight is unimportant for many practical purposes because, to a reasonable approximation, the strength of gravity is the same everywhere on the surface of the Earth. In such a constant gravitational field, the gravitational force exerted on an object (its weight) is directly proportional to its mass. So, if object A weighs, say, 10 times as much as object B, then object A's mass is 10 times that of object B. This means that an object's mass can be measured indirectly by its weight (for conversion formulas see below). For example, when we buy a bag of sugar we can measure its weight (how hard it presses down on the scales) and be sure that this will give a good indication of the quantity that we are actually interested in, which is the mass of sugar in the bag. Nevertheless, slight variations in the Earth's gravitational field do exist (see Earth's gravity), and these must be taken into account in high precision weight measurements.
The use of "weight" for "mass" also persists in some scientific terminology – for example, in the chemical terms "atomic weight", "molecular weight", and "formula weight", rather than the preferred "atomic mass" etc.
The difference between mass and force becomes obvious when:
- objects are compared in different gravitational fields, such as away from the Earth's surface. For example, on the surface of the Moon, gravity is only about one-sixth as strong as on the surface of the Earth. A one-kilogram mass is still a one-kilogram mass (as mass is an intrinsic property of the object) but the downwards force due to gravity is only one-sixth of what the object would experience on Earth.
- masses are considered in the context of a lever, such as a cantilever structure.
- locating the center of gravity of an object.
# Units of weight (force)
Systems of units of weight (force) and mass have a tangled history, partly because the distinction was not properly understood when many of the units first came into use.
## SI units
In most modern scientific work, physical quantities are measured in SI units. The SI unit of mass is the kilogram. The SI unit of force (and hence weight) is the newton (N) – which can also be expressed in SI base units as kg·m/s² (kilograms times meters per second squared).
The kilogram-force is a non-SI unit of force, defined as the force exerted by a one-kilogram mass in standard Earth gravity (equal to about 9.8 newtons).
The gravitational force exerted on an object is proportional to the mass of the object, so it is reasonable to think of the strength of gravity as measured in terms of force per unit mass, that is, newtons per kilogram (N/kg). However, the unit N/kg resolves to m/s²; (metres per second per second), which is the SI unit of acceleration, and in practice gravitational strength is usually quoted as an acceleration.
## The pound and related units
In United States customary units, the pound can be either a unit of force or a unit of mass. Related units used in some distinct, separate subsystems of units include the poundal and the slug. The poundal is defined as the force necessary to accelerate a one-pound object at 1 ft/s², and is equivalent to about 1/32 of a pound (force). The slug is defined as the amount of mass that accelerates at 1 ft/s² when a pound of force is exerted on it, and is equivalent to about 32 pounds (mass).
## Conversion between weight (force) and mass
To convert between weight (force) and mass we use Newton's second law, F = ma (force = mass × acceleration). Here, F is the force due to gravity (i.e. the weight force), m is the mass of the object in question, and a is the acceleration due to gravity, on Earth approximately 9.8 m/s² or 32 ft/s²). In this context the same equation is often written as W = mg, with W standing for weight, and g for the acceleration due to gravity.
# Sensation of weight
The weight force that we actually sense is not the downward force of gravity, but the normal force (an upward contact force) exerted by the surface we stand on, which opposes gravity and prevents us falling to the center of the Earth. This normal force, called the apparent weight, is the one that is measured by a spring scale.
For a body supported in a stationary position, the normal force balances the earth's gravitational force, and so apparent weight has the same magnitude as actual weight. (Technically, things are slightly more complicated. For example, an object immersed in water weighs less, according to a spring scale, than the same object in air; this is due to buoyancy, which opposes the weight force and therefore generates a smaller normal. These and other factors are explained further under apparent weight.)
If there is no contact with any surface to provide such an opposing force then there is no sensation of weight (no apparent weight). This happens in free-fall, as experienced by sky-divers (until they approach terminal velocity) and astronauts in orbit, who feel "weightless" even though their bodies are still subject to the force of gravity: they're just no longer resisting it. The experience of having no apparent weight is also known as microgravity.
A degree of reduction of apparent weight occurs, for example, in elevators. In an elevator, a spring scale will register a decrease in a person's (apparent) weight as the elevator starts to accelerate downwards. This is because the opposing force of the elevator's floor decreases as it accelerates away underneath one's feet.
# Measuring weight
Weight is commonly measured using one of two methods. A spring scale or hydraulic or pneumatic scale measures weight force (strictly apparent weight force) directly. If the intention is to measure mass rather than weight, then this force must be converted to mass. As explained above, this calculation depends on the strength of gravity. Household and other low precision scales that are calibrated in units of mass (such as kilograms) assume roughly that standard gravity will apply. However, although nearly constant, the apparent or actual strength of gravity does in fact vary very slightly in different places on the earth (see standard gravity, physical geodesy, gravity anomaly and gravity). This means that same object (the same mass) will exert a slightly different weight force in different places. High precision spring scales intended to measure mass must therefore be calibrated specifically according their location on earth.
Mass may also be measured with a balance, which compares the item in question to others of known mass. This comparison remains valid whatever the local strength of gravity. If weight force, rather than mass, is required, then this can be calculated by multiplying mass by the acceleration due to gravity – either standard gravity (for everyday work) or the precise local gravity (for precision work).
Gross weight is a term that generally is found in commerce or trade applications, and refers to the gross or total weight of a product and its packaging. Conversely, net weight refers to the intrinsic weight of the product itself, discounting the weight of packaging or other materials.
# Relative weights on the Earth, other planets and the Moon
The following is a list of the weights of a mass on the surface of some of the bodies in the solar system, relative to its weight on Earth: | https://www.wikidoc.org/index.php/Weight | |
811a35f43f2a330e8955be7ea840003a8fe83872 | wikidoc | Willow | Willow
The Willows are a family of trees and shrubs which differ greatly in size and habit of growth but are very much alike in other respects. There are about 350 species in this genus worldwide, found primarily on moist soils in cooler zones in the Northern Hemisphere. Willows are very cross-fertile and numerous hybrids are known, both naturally occurring and in cultivation.
Some smaller species may also be known by the common names osier and sallow; the latter name is derived from the same root as the Latin salix.
Some willows, particularly arctic and alpine species, are very small; the Dwarf Willow (Salix herbacea) rarely exceeds 6 cm in height, though spreading widely across the ground.
The Weeping Willow, very widely planted as an ornamental tree, is a cultivar, Salix × sepulcralis 'Chrysocoma', derived from a hybrid between the Chinese Peking Willow and the European White Willow.
# Description
The willows all have abundant watery juice, furrowed scaly bark which is heavily charged with salicylic acid, soft, pliant, tough wood, slender branches and large fibrous often stoloniferious roots. These roots are remarkable for their toughness, size, and tenacity of life.
The leaves are deciduous, often elongated but round to oval in a few species, and with a serrated margin. All the buds are lateral; no absolutely terminal bud is ever formed. These are covered by a single scale, inclosing at its base two minute opposite buds, alternate with two, small, scale-like, fugacious, opposite leaves. The leaves are alternate except the first pair which fall when about an inch long. They are simple, feather-veined, and typically linear-lanceolate. Usually they are serrate, rounded at base, acute or acuminate. In color they show a great variety of greens, ranging from yellow to blue.
## Flowers
Willows are dioecious with male and female flowers appearing as catkins on different plants; the catkins are produced early in the spring, often before the leaves or as the new leaves open. The petioles are short, the stipules often very conspicuous, looking like tiny round leaves and sometimes remaining for half the summer. On some species, however, they are small, inconspicuous, and fugacious.
The staminate flowers are without either calyx or corolla; they consist simply of stamens, in number varying from two to ten, accompanied by a nectariferous gland and inserted on the base of a scale which is itself borne on the rachis of a drooping raceme called a catkin, or ament. This scale is oval and entire and very hairy. The anthers are rose colored in the bud but orange or purple after the flower opens, they are two-celled and the cells open longitudinally. The filaments are threadlike, usually pale yellow, often hairy.
The pistillate flowers are also without calyx or corolla; and consist of a single ovary accompanied by a small flat gland and inserted on the base of a scale which is likewise borne on the rachis of a catkin. The ovary is one-celled, the style two-lobed, and the ovules numerous.
## Fruit
The fruit is a small capsule containing numerous tiny (0.1 mm) seeds embedded in white down, which assists wind dispersal of the seeds. The fruit is a one-celled, two-valved, cylindrical, beaked capsule, containing many minute seeds which are furnished with long, silky, white hairs. The catkins appear before or with the leaves.
# Cultivation
Almost all willows take root very readily from cuttings or where broken branches lie on the ground. There are a few exceptions, including the Goat Willow and Peachleaf Willow. One famous example of such growth from cuttings involves the poet Alexander Pope, who begged a twig from a parcel tied with twigs sent from Spain to Lady Suffolk. This twig was planted and thrived, and legend has it that all of England's Weeping Willows are descended from this first one .
Willows are often planted on the borders of streams in order that their interlacing roots may protect the bank against the action of the water. Frequently the roots are much larger than the stem which grows from them
# Ecological issues
Willows are used as food plants by the larvae of some Lepidoptera species - see list of Lepidoptera which feed on Willows.
A number of willow species were widely planted in Australia in the distant, far-off past, notably as erosion control measures along watercourses. They are now regarded as an invasive weed and many catchment management authorities are removing them to be replaced with native trees .. .
# Uses
## Medicinal uses
The leaves and bark of the willow tree have been mentioned in ancient texts from Assyria, Sumer and Egypt as a remedy for aches and fever, and the Greek physician Hippocrates wrote about its medicinal properties in the 5th century BC. Native Americans across the American continent relied on it as a staple of their medical treatments.
In 1763 its medicinal properties were observed by the Reverend Edward Stone in England. He notified the Royal Society who published his findings. The active extract of the bark, called salicin, was isolated to its crystalline form in 1828 by Henri Leroux, a French pharmacist, and Raffaele Piria, an Italian chemist, who then succeeded in separating out the acid in its pure state. Salicin is acidic when in a saturated solution in water (pH = 2.4), and is called salicylic acid for that reason.
In 1897 Felix Hoffmann created a synthetically altered version of salicin (in his case derived from the Spiraea plant), which caused less digestive upset than pure salicylic acid. The new drug, formally Acetylsalicylic acid, was named aspirin by Hoffmann's employer Bayer AG. This gave rise to the hugely important class of drugs known as non-steroidal anti-inflammatory drugs (NSAIDs).
## Other uses
- As part of the four species used on the Jewish holiday of Sukkot.
- Living Willow Sculpture
# Willow in human culture
Willow was famous subject in many East Asian nations' cultures. It captured in many poems of Koreans. Gisaeng Hongrang lived in the middle of the Joseon period wrote: like willow I will be the willow on your bedside. Hongrang wrote this poem by the willow in the rain in the evening which gave to her parting lover.
# Pictures
- Weeping Willow in Auckland, New Zealand
Weeping Willow in Auckland, New Zealand
- Salix herbacea, Dwarf Willow, Sweden
Salix herbacea, Dwarf Willow, Sweden
- Willow catkin (Salix discolor)
Willow catkin(Salix discolor)
- Willow catkin (Salix caprea)
Willow catkin(Salix caprea)
- Willow Leaves
Willow Leaves | Willow
Template:Alternateuses
The Willows are a family of trees and shrubs which differ greatly in size and habit of growth but are very much alike in other respects. There are about 350 species in this genus worldwide, found primarily on moist soils in cooler zones in the Northern Hemisphere. Willows are very cross-fertile and numerous hybrids are known, both naturally occurring and in cultivation.
Some smaller species may also be known by the common names osier and sallow; the latter name is derived from the same root as the Latin salix.
Some willows, particularly arctic and alpine species, are very small; the Dwarf Willow (Salix herbacea) rarely exceeds 6 cm in height, though spreading widely across the ground.
The Weeping Willow, very widely planted as an ornamental tree, is a cultivar, Salix × sepulcralis 'Chrysocoma', derived from a hybrid between the Chinese Peking Willow and the European White Willow.
# Description
The willows all have abundant watery juice, furrowed scaly bark which is heavily charged with salicylic acid, soft, pliant, tough wood, slender branches and large fibrous often stoloniferious roots. These roots are remarkable for their toughness, size, and tenacity of life.
The leaves are deciduous, often elongated but round to oval in a few species, and with a serrated margin. All the buds are lateral; no absolutely terminal bud is ever formed. These are covered by a single scale, inclosing at its base two minute opposite buds, alternate with two, small, scale-like, fugacious, opposite leaves. The leaves are alternate except the first pair which fall when about an inch long. They are simple, feather-veined, and typically linear-lanceolate. Usually they are serrate, rounded at base, acute or acuminate. In color they show a great variety of greens, ranging from yellow to blue.
## Flowers
Willows are dioecious with male and female flowers appearing as catkins on different plants; the catkins are produced early in the spring, often before the leaves or as the new leaves open. The petioles are short, the stipules often very conspicuous, looking like tiny round leaves and sometimes remaining for half the summer. On some species, however, they are small, inconspicuous, and fugacious.
The staminate flowers are without either calyx or corolla; they consist simply of stamens, in number varying from two to ten, accompanied by a nectariferous gland and inserted on the base of a scale which is itself borne on the rachis of a drooping raceme called a catkin, or ament. This scale is oval and entire and very hairy. The anthers are rose colored in the bud but orange or purple after the flower opens, they are two-celled and the cells open longitudinally. The filaments are threadlike, usually pale yellow, often hairy.
The pistillate flowers are also without calyx or corolla; and consist of a single ovary accompanied by a small flat gland and inserted on the base of a scale which is likewise borne on the rachis of a catkin. The ovary is one-celled, the style two-lobed, and the ovules numerous.
## Fruit
The fruit is a small capsule containing numerous tiny (0.1 mm) seeds embedded in white down, which assists wind dispersal of the seeds. The fruit is a one-celled, two-valved, cylindrical, beaked capsule, containing many minute seeds which are furnished with long, silky, white hairs. The catkins appear before or with the leaves.
# Cultivation
Almost all willows take root very readily from cuttings or where broken branches lie on the ground. There are a few exceptions, including the Goat Willow and Peachleaf Willow. One famous example of such growth from cuttings involves the poet Alexander Pope, who begged a twig from a parcel tied with twigs sent from Spain to Lady Suffolk. This twig was planted and thrived, and legend has it that all of England's Weeping Willows are descended from this first one [1].
Willows are often planted on the borders of streams in order that their interlacing roots may protect the bank against the action of the water. Frequently the roots are much larger than the stem which grows from them
# Ecological issues
Willows are used as food plants by the larvae of some Lepidoptera species - see list of Lepidoptera which feed on Willows.
A number of willow species were widely planted in Australia in the distant, far-off past, notably as erosion control measures along watercourses. They are now regarded as an invasive weed and many catchment management authorities are removing them to be replaced with native trees [2].. [3].
# Uses
## Medicinal uses
The leaves and bark of the willow tree have been mentioned in ancient texts from Assyria, Sumer and Egypt[1] as a remedy for aches and fever,[2] and the Greek physician Hippocrates wrote about its medicinal properties in the 5th century BC. Native Americans across the American continent relied on it as a staple of their medical treatments.
In 1763 its medicinal properties were observed by the Reverend Edward Stone in England. He notified the Royal Society who published his findings. The active extract of the bark, called salicin, was isolated to its crystalline form in 1828 by Henri Leroux, a French pharmacist, and Raffaele Piria, an Italian chemist, who then succeeded in separating out the acid in its pure state. Salicin is acidic when in a saturated solution in water (pH = 2.4), and is called salicylic acid for that reason.
In 1897 Felix Hoffmann created a synthetically altered version of salicin (in his case derived from the Spiraea plant), which caused less digestive upset than pure salicylic acid. The new drug, formally Acetylsalicylic acid, was named aspirin by Hoffmann's employer Bayer AG. This gave rise to the hugely important class of drugs known as non-steroidal anti-inflammatory drugs (NSAIDs).
## Other uses
- As part of the four species used on the Jewish holiday of Sukkot.
- Living Willow Sculpture
# Willow in human culture
Willow was famous subject in many East Asian nations' cultures. It captured in many poems of Koreans. Gisaeng Hongrang lived in the middle of the Joseon period wrote: like willow I will be the willow on your bedside. Hongrang wrote this poem by the willow in the rain in the evening which gave to her parting lover.
[3]
# Pictures
- Weeping Willow in Auckland, New Zealand
Weeping Willow in Auckland, New Zealand
- Salix herbacea, Dwarf Willow, Sweden
Salix herbacea, Dwarf Willow, Sweden
- Willow catkin (Salix discolor)
Willow catkin(Salix discolor)
- Willow catkin (Salix caprea)
Willow catkin(Salix caprea)
- Willow Leaves
Willow Leaves | https://www.wikidoc.org/index.php/Willow | |
f1b85344ed1615d8a07b5bd15bc2cb970b0ecb9a | wikidoc | X-rays | X-rays
X-radiation (composed of X-rays, or Röntgen rays) is a form of electromagnetic radiation with a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequencies in the range 30 petahertz (PHz) to 30 exahertz (EHz) (3 × 1016 Hz to 3 × 1019 Hz) and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays. In many languages it is called Röntgen radiation after one of the first investigators of the X-rays, Wilhelm Conrad Röntgen. Röntgen had called them X-rays to signify an unknown type of radiation.
X-rays are primarily used for diagnostic radiography and crystallography. As a result, the term X-ray is metonymically used to refer to a radiographic image produced using this method, in addition to the method itself. X-rays are a form of ionizing radiation and as such can be dangerous. From about 0.12 to 12 keV they are classified as soft X-rays, and from about 12 to 120 keV as hard X-rays, due to their penetrating abilities.
The distinction between X-rays and gamma rays has changed in recent decades. Originally, the electromagnetic radiation emitted by X-ray tubes had a longer wavelength than the radiation emitted by radioactive nuclei (gamma rays). So older literature distinguished between X- and gamma radiation on the basis of wavelength, with radiation shorter than some arbitrary wavelength, such as 10−11 m, defined as gamma rays. However, as shorter wavelength continuous spectrum "X-ray" sources such as linear accelerators and longer wavelength "gamma ray" emitters were discovered, the wavelength bands largely overlapped. The two types of radiation are now usually defined by their origin: X-rays are emitted by electrons outside the nucleus, while gamma rays are emitted by the nucleus.
# Unit of measure and exposure
The measure of X-rays ionizing ability is called the exposure:
- The coulomb per kilogram (C/kg) is the SI unit of ionizing radiation exposure, and measures the amount of radiation required to create 1 coulomb of charge of each polarity in 1 kilogram of matter.
- The röntgen (R) is an obsolete older traditional unit of exposure, which represented the amount of radiation required to create 1 esu of charge of each polarity in 1 cubic centimeter of dry air. 1 röntgen = 2.58×10−4 C/kg
However, the effect of ionizing radiation on matter (especially living tissue) is more closely related to the amount of energy deposited rather than the charge. This is called the absorbed dose:
- The gray (Gy) which has units of (J/kg), is the SI unit of absorbed dose which is the amount of radiation required to deposit 1 joule of energy in 1 kilogram of any kind of matter.
- The rad is the (obsolete) corresponding traditional unit, equal to 0.01 J deposited per kg. 100 rad = 1 Gy.
The equivalent dose is the measure of the biological effect of radiation on human tissue. For X-rays it is equal to the absorbed dose. The rem is the traditional unit of dose equivalent. This describes the Energy delivered by \gamma or X-radiation (indirectly ionizing radiation) for humans. The SI counterpart is the Sievert (Sv). One Sievert is equal to 100 rem. Because the rem is a relatively large unit, typical equivalent dose is measured in millirem (mrem), or one thousandth of a rem. In microsievert (μSv) - 1/1000000 Sv -, 1 mrem equals 10 μSv.
Medical X-rays are a major source of manmade radiation exposure, accounting for 58% in the USA in 1987, but since most radiation exposure is natural (82%) it only accounts for 10% of total USA radiation exposure. The average person living in the United States is exposed to approximately 150 mrem annually from background sources alone.
Reported dosage due to dental X-rays seems to vary significantly. Depending on the source, a typical dental X-ray of a human results in an exposure of perhaps, 3, 40, 300, or as many as 900 mrems (30 to 9,000 μSv).
# Medical Physics
X-rays are a type of electromagnetic radiation with wavelengths of around 10-10 meters. When medical X-rays are being produced, a thin metallic sheet is placed between the emitter and the target, effectively filtering out the lower energy (soft) X-rays. This is often placed close to the window of the X-ray tube. The resultant X-ray is said to be hard. Soft X-rays overlap the range of extreme ultraviolet. The frequency of hard X-rays is higher than that of soft X-rays, and the wavelength is shorter. Hard X-rays overlap the range of "long"-wavelength (lower energy) gamma rays, however the distinction between the two terms depends on the source of the radiation, not its wavelength; X-ray photons are generated by energetic electron processes, gamma rays by transitions within atomic nuclei.
The basic production of X-rays is by accelerating electrons in order to collide with a metal target. In medical applications, this is usually tungsten or a more crack resistant alloy of rhenium (5%) and tungsten (95%), but sometimes molybdenum for more specialised applications, such as when soft X-rays are needed as in mammography. In crystallography, a copper target is most common, with cobalt often being used when fluorescence from iron content in the sample might otherwise present a problem. Here the electrons suddenly decelerate upon colliding with the metal target and if enough energy is contained within the electron it is able to knock out an electron from the inner shell of the metal atom and as a result electrons from higher energy levels then fill up the vacancy and X-ray photons are emitted. This process is extremely inefficient (~0.1%) and thus to produce reasonable flux of X-rays plenty of energy has to be wasted into heat which has to be removed. The maximum energy of the produced X-ray photon in keV is limited by the energy of the incident electron, which is equal to the voltage on the tube, so an 80 kV tube can't create higher than 80 keV X-rays. The voltages used in diagnostic X-ray tubes, and thus the highest energies of the X-rays, range from roughly 20 to 150 kV.
The spectral lines generated depends on the target (anode) element used and thus are called characteristic lines. Usually these are transitions from upper shells into K shell (called K lines), into L shell (called L lines) and so on. There is also a continuum Bremsstrahlung radiation given off by the electrons as they are scattered by the strong electric field near the high-Z (proton number) nuclei. In medical diagnostic applications, the low energy (soft) X-rays are unwanted, since they are totally absorbed by the body, increasing the dose. A thin metal (often aluminum, but can be one of many X-Ray filters) sheet is placed over the window of the X-ray tube, filtering out the low energy end of the spectrum.
X-rays can detect cancer, cysts, and tumors. Due to their short wavelength, in medical applications X-rays act more like a particle than a wave. This is in contrast to their application in crystallography, where their wave-like nature is most important.
Nowadays, for many (non-medical) applications, X-ray production is achieved by synchrotrons (see synchrotron light). Its unique features are brightness many orders of magnitude greater than X-ray tubes, wide spectrum, high collimation, and linear polarization.
To create a blood or artery X-ray, also called digital angiography, iodine is injected into the veins and a digitized image is created. Then, a second image is established of only the parts of the X-rayed section without iodine. The first image is subtracted then a final image is produced containing both the first and second images together. Lastly, the results are printed. The doctor or surgeon then compares the results of the angiography to a perfect angiography structure to see if there are any malfunctions.
To take an X-ray of the bones, no iodization is required. Short X-ray pulses are shot through a body at first. Next, the bones absorb the most waves because they are more dense and contain Ca which absorbs stronger than the carbon, oxygen, and nitrogen atoms of soft tissue (due to more electrons in Ca atom). The X-rays that do not get absorbed turn the photographic film from white to black, leaving a white shadow of bones on the film.
# Detectors
## Photographic plate
The detection of X-rays is based on various methods. The most commonly known methods, "Image Receptors" (IR), are a photographic plate, X-ray film in a cassette, and rare earth screens.
A photographic plate or film is used in hospitals to produce images of the internal organs and bones of a patient. They are also used in industrial radiography processes, for example, to inspect welded seams. Since photographic plates are sensitive to X-rays, they provide a convenient and easy means of recording the image. X-ray film is usually provided as pre-loaded paper cartridges with the film inside a light proof paper envelope. An additional paper coated in a thin layer of lead is often included in contact with the photographic film. The lead reflects the x-rays back through the photo film to more or less double the sensitivity of the assembly. Thus, photographic film has to be used the right way round, and is marked as such. The emulsion is frequently coated on both sides of the film or plate in order to increase the sensitivity further.
The part of the patient to be X-rayed is placed between the X-ray source and the photographic receptor to produce what is a shadow of all the internal structure of that particular part of the body being X-rayed. The X-rays are blocked by dense tissues such as bone and pass through soft tissues. Those areas where the X-rays strike the photographic receptor turn black when it is developed. So where the X-rays pass through "soft" parts of the body such as organs, muscle, and skin, the plate or film turns black. Contrast compounds, containing high atomic numbered elements such as barium or iodine, which are radiopaque, can be injected in the artery of a particular organ, or given intravenously. The contrast compounds essentially block the X-rays and hence the circulation of the organ can be more readily seen. Many years ago thorium was used as a contrast medium (Thorotrast) — this caused many people to be injured or even die from the effects of the radiation from the thorium.
Photographic plates are losing favour in many X-ray facilities because of the necessity to have processing facilities readily at hand, and because the photographic plates themselves, plus the processing chemicals are relatively expensive consumables. Silver (necessary to the radiographic and photographic industry) is a non-renewable resource. Computed (CR) and digital radiography (DR) has started to replace film. Archiving of these new technologies is also space saving for facilities. Each IR technology required a lot of exposure (to the patient). This has been reduced by the use of intensifying screens.
## Photostimulable Phosphors (PSPs)
An increasingly common method of detecting X-rays is the use of Photostimulable Luminescence (PSL), pioneered by Fuji in the 1980s. In modern hospitals a PSP plate is used in place of the photographic plate. After the plate is X-rayed, excited electrons in the phosphor material remain 'trapped' in 'colour centres' in the crystal lattice until stimulated by a laser beam passed over the plate surface. The light given off during laser stimulation is collected by a photomultiplier tube and the resulting signal is converted into a digital image by computer technology, which gives this process its common name, computed radiography (also referred to as digital radiography). The PSP plate can be used over and over again, and existing x-ray equipment requires no modification to use them.
## Geiger counter
Initially, most common detection methods were based on the ionization of gases, as in the Geiger-Müller counter: a sealed volume, usually a cylinder, with a polymer or thin metal window contains a gas, and a wire, and a high voltage is applied between the cylinder (cathode) and the wire (anode). When an X-ray photon enters the cylinder, it ionizes the gas and forms ions and electrons. Electrons accelerate toward the anode, in the process causing further ionization along their trajectory. This process, known as an avalanche, is detected as a sudden flow of current, called a "count" or "event".
Ultimately, the electrons form a virtual cathode around the anode wire drastically reducing the electric field in the outer portions of the tube. This halts the collisional ionizations and limits further growth of avalanches. As a result, all "counts" on a Geiger counter are the same size and it can give no indication as to the particle energy of the radiation, unlike the proportional counter. The intensity of the radiation is measurable by the Geiger counter as the counting-rate of the system.
In order to gain energy spectrum information a diffracting crystal may be used to first separate the different photons, the method is called wavelength dispersive X-ray spectroscopy (WDX or WDS). Position-sensitive detectors are often used in conjunction with dispersive elements. Other detection equipment may be used which are inherently energy-resolving, such as the aforementioned proportional counters. In either case, use of suitable pulse-processing (MCA) equipment allows digital spectra to be created for later analysis.
For many applications, counters are not sealed but are constantly fed with purified gas (thus reducing problems of contamination or gas aging). These are called "flow counter".
## Scintillators
Some materials such as sodium iodide (NaI) can "convert" an X-ray photon to a visible photon; an electronic detector can be built by adding a photomultiplier. These detectors are called "scintillators", filmscreens or "scintillation counters". The main advantage of using these is that an adequate image can be obtained while subjecting the patient to a much lower dose of X-rays.
## Image intensification
X-rays are also used in "real-time" procedures such as angiography or contrast studies of the hollow organs (e.g. barium enema of the small or large intestine) using fluoroscopy acquired using an X-ray image intensifier. Angioplasty, medical interventions of the arterial system, rely heavily on X-ray-sensitive contrast to identify potentially treatable lesions.
## Direct semiconductor detectors
Since the 1970s, new semiconductor detectors have been developed (silicon or germanium doped with lithium, Si(Li) or Ge(Li)). X-ray photons are converted to electron-hole pairs in the semiconductor and are collected to detect the X-rays. When the temperature is low enough (the detector is cooled by Peltier effect or even cooler liquid nitrogen), it is possible to directly determine the X-ray energy spectrum; this method is called energy dispersive X-ray spectroscopy (EDX or EDS); it is often used in small X-ray fluorescence spectrometers. These detectors are sometimes called "solid state detectors". Cadmium telluride (CdTe) and its alloy with zinc, cadmium zinc telluride detectors have an increased sensitivity, which allows lower doses of X-rays to be used.
Practical application in medical imaging didn't start taking place until the 1990s. Currently amorphous selenium is used in commercial large area flat panel X-ray detectors for mammography and chest radiography. Current research and development is focussed around pixel detectors, such as CERN's energy resolving Medipix detector.
Note: A standard semiconductor diode, such as a 1N4007, will produce a small amount of current when placed in an X-ray beam. A test device once used by Medical Imaging Service personnel was a small project box that contained several diodes of this type in series, which could be connected to an oscilloscope as a quick diagnostic.
Silicon drift detectors (SDDs), produced by conventional semiconductor fabrication, now provide a cost-effective and high resolving power radiation measurement. Unlike conventional X-ray detectors, such as Si(Li)s, they do not need to be cooled with liquid nitrogen.
## Scintillator plus semiconductor detectors (indirect detection)
With the advent of large semiconductor array detectors it has become possible to design detector systems using a scintillator screen to convert from X-rays to visible light which is then converted to electrical signals in an array detector. Indirect Flat Panel Detectors (FPDs) are in widespread use today in medical, dental, veterinary and industrial applications. A common form of these detectors is based on amorphous silicon thin film transistor (TFT)/photodiode arrays.
The array technology is a variant on the amorphous silicon TFT arrays used in many flat panel displays, like the ones in computer laptops. The array consists of a sheet of glass covered with a thin layer of silicon that is in an amorphous or disordered state. At a microscopic scale, the silicon has been imprinted with millions of transistors arranged in a highly ordered array, like the grid on a sheet of graph paper. Each of these TFTs is attached to a light-absorbing photodiode making up an individual pixel (picture element). Photons striking the photodiode are converted into two carriers of electrical charge, called electron-hole pairs. Since the number of charge carriers produced will vary with the intensity of incoming light photons, an electrical pattern is created that can be swiftly converted to a voltage and then a digital signal, which is interpreted by a computer to produce a digital image. Although silicon has outstanding electronic properties, it is not a particularly good absorber of X-ray photons. For this reason, X-rays first impinge upon scintillators made from eg. gadolinium oxysulfide or cesium iodide. The scintillator absorbs the X-rays and converts them into visible light photons that then pass onto the photodiode array.
## Visibility to the human eye
While generally considered invisible to the human eye, in special circumstances X-rays can be visible. Brandes, in an experiment a short time after Röntgen's landmark 1895 paper, reported after dark adaptation and placing his eye close to an X-ray tube, seeing a faint "blue-gray" glow which seemed to originate within the eye itself. Upon hearing this, Röntgen reviewed his record books and found he too had seen the effect. When placing an X-ray tube on the opposite side of a wooden door Röntgen had noted the same blue glow, seeming to emanate from the eye itself, but thought his observations to be spurious because he only saw the effect when he used one type of tube. Later he realized that the tube which had created the effect was the only one powerful enough to make the glow plainly visible and the experiment was thereafter readily repeatable. The knowledge that X-rays are actually faintly visible to the dark-adapted naked eye has largely been forgotten today; this is probably due to the desire not to repeat what would now be seen as a recklessly dangerous and harmful experiment with ionizing radiation. It is not known what exact mechanism in the eye produces the visibility: it could be due to conventional detection (excitation of rhodopsin molecules in the retina), direct excitation of retinal nerve cells, or secondary detection via, for instance, X-ray induction of phosphorescence in the eyeball with conventional retinal detection of the secondarily produced visible light.
If the intensity of an X-ray beam is high enough, the ionization of the air will make the beam visible with a white glow. The beamline from the wiggler at the ID11 at ESRF is one example of such high intensity.
# Medical uses
Since Röntgen's discovery that X-rays can identify bony structures, X-rays have been developed for their use in medical imaging. Radiology is a specialized field of medicine. Radiographers employ radiography and other techniques for diagnostic imaging. Indeed, this is probably the most common use of X-ray technology.
X-rays are especially useful in the detection of pathology of the skeletal system, but are also useful for detecting some disease processes in soft tissue. Some notable examples are the very common chest X-ray, which can be used to identify lung diseases such as pneumonia, lung cancer or pulmonary edema, and the abdominal X-ray, which can detect ileus (blockage of the intestine), free air (from visceral perforations) and free fluid (in ascites). In some cases, the use of X-rays is debatable, such as gallstones (which are rarely radiopaque) or kidney stones (which are often visible, but not always). Also, traditional plain X-rays pose very little use in the imaging of soft tissues such as the brain or muscle. Imaging alternatives for soft tissues are computed axial tomography (CAT or CT scanning), magnetic resonance imaging (MRI) or ultrasound. Since 2005, X-rays are listed as a carcinogen by the U.S. government. The benefits of the X-ray investigation should be balanced with the potential hazards to the unborn fetus.
Radiotherapy, a curative medical intervention, now used almost exclusively for cancer, employs higher energies of radiation.
The efficiency of X-ray tubes is less than 2%. Most of the energy is used to heat up the anode.
# Shielding against X-Rays
Lead is the most common shield against X-Rays because of its high density (11340 kg/m3), ease of installation and low cost. The maximum range of a high-energy photon such as an X-ray in matter is infinite - at every point in the matter traversed by the photon, there is a probability of interaction. Thus there is a very small probability of no interaction over very large distances. The shielding of photons is therefore exponential - doubling the thickness of shielding will square the shielding effect.
The following table shows the recommended thickness of lead shielding in function of X-Ray energy, from the Recommendations by the Second International Congress of Radiology.
# Other uses
Notable uses of X-rays include
- X-ray crystallography in which the pattern produced by the diffraction of X-rays through the closely spaced lattice of atoms in a crystal is recorded and then analyzed to reveal the nature of that lattice. A related technique, fiber diffraction, has been most notably used by Watson and Crick to discover the double helix structure of DNA.
- X-ray astronomy, which is an observational branch of astronomy, which deals with the study of X-ray emission from celestial objects.
- X-ray microscopic analysis, which uses soft X-rays to produce images of very small objects.
- X-ray fluorescence, a technique in which X-rays are generated within a specimen and detected. The outgoing energy of the X-ray can be used to identify the composition of the sample.
- Industrial radiography uses X-rays for inspection of industrial parts, particularly welds.
- Paintings are often X-rayed to reveal the underdrawing and pentimenti or alterations in the course of painting, or by later restorers. Many pigments such as lead white show well in X-ray photographs.
- Airport security luggage scanners use X-rays for inspecting the interior of luggage for security threats before loading on aircraft.
- X-ray fine art photography.
- Roentgen Stereophotogrammetry is used to track movement of bones based on the implantation of markers.
# History
Among the important early researchers in X-rays were Professor Ivan Pulyui, Sir William Crookes, Johann Wilhelm Hittorf, Eugen Goldstein, Heinrich Hertz, Philipp Lenard, Hermann von Helmholtz, Nikola Tesla, Thomas Edison, Charles Glover Barkla, Max von Laue, and Wilhelm Conrad Röntgen.
## Johann Hittorf
Physicist Johann Hittorf (1824 - 1914) observed tubes with energy rays extending from a negative electrode. These rays produced a fluorescence when they hit the glass walls of the tubes. In 1876 the effect was named "cathode rays" by Eugen Goldstein, and today are known to be streams of electrons. Later, English physicist William Crookes investigated the effects of electric currents in gases at low pressure, and constructed what is called the Crookes tube. It is a glass cylinder mostly (but not completely) evacuated, containing electrodes for discharges of a high voltage electric current. He found, when he placed unexposed photographic plates near the tube, that some of them were flawed by shadows, though he did not investigate this effect. Crookes also noted that his cathode rays caused the glass walls of his tube to glow a dull blue colour. Crookes failed to realise that it wasn't actually the cathode rays that caused the blue glow, but the low level x-rays produced when the cathode rays struck the glass. Crookes tubes created electrons by ionization of the residual air in the tube by a high DC voltage of anywhere between a few kilovolts and 100 kV. This voltage accelerated the electrons coming from the cathode to a high enough velocity that they created X-rays when they struck the anode or the glass wall of the tube. Many of the early Crookes tubes undoubtedly radiated X-rays, because early researchers noticed effects that were attributable to them.
## Ivan Pulyui
In 1877 Ukranian-born Ivan Pulyui, a lecturer in experimental physics at the University of Vienna, constructed various designs of Geissler vacuum discharge tube to investigate their properties. He continued his investigations when appointed professor at the Czech Technical University in Prague (Prague Polytechnic). In 1886 he found that sealed photographic plates became dark when exposed to the emanations from the tubes. Early in 1896, just a few weeks after Röntgen published his first X-ray photograph, Pulyui published high-quality x-ray images in journals in Paris and London. Although Pulyui had studied with Röntgen at the University of Strasbourg in the years 1873-75, his biographer Gaida (1997) asserts that his subsequent research was conducted independently.
As a result of experiments into what he called cold light Ivan Pulyui is reputed to have developed an X-ray emitting device as early as 1881. He reputedly first demonstrated an X-ray photograph of a 13-year-old boy's broken arm and an X-ray photograph of his daughter's hand with a pin lying under it. The device became known as the Pulyui lamp and was mass-produced for a period. Reputedly, Pulyui personally presented one to Wilhelm Conrad Röntgen who went on to be credited as the major developer of the technology. Pulyui published his results in a scientific paper, Luminous Electrical Matter and the Fourth State of Matter in the Notes of the Austrian Imperial Academy of Sciences (1880-1883), but expressed his ideas in an obscure manner using obsolete terminology. Pulyui did gain some recognition when the work was translated and published as a book by the Royal Society in the UK. Pulyui made many other discoveries as well. He is particularly noted for inventing a device for determining the mechanical equivalent of heat that was exhibited at the Exposition Universelle, Paris, 1878. Pulyui also participated in opening of several power plants in Austria-Hungary.
The first medical X-ray made in the United States was obtained using a discharge tube of Pulyui's design. In January 1896, on reading of Röntgen's discovery, Frank Austin of Dartmouth College tested all of the discharge tubes in the physics laboratory and found that only the Pulyui tube produced X-rays. This was a result of Pulyui's inclusion of an oblique "target" of mica, used for holding samples of fluorescent material, within the tube. On 3 February 3, 1896 Gilman Frost, professor of medicine at the college, and his brother Edwin Frost, professor of physics, exposed the wrist of Eddie McCarthy, whom Edwin had treated some weeks earlier for a fracture, to the x-rays and collected the resulting image of the broken bone on gelatin photographic plates obtained from Howard Langill, a local photographer also interested in Röntgen's work.
## Nikola Tesla
In April 1887, Nikola Tesla began to investigate X-rays using high voltages and tubes of his own design, as well as Crookes tubes. From his technical publications, it is indicated that he invented and developed a special single-electrode X-ray tube , which differed from other X-ray tubes in having no target electrode. The principle behind Tesla's device is nowadays called the Bremsstrahlung process, in which a high-energy secondary X-ray emission is produced when charged particles (such as electrons) pass through matter. By 1892, Tesla performed several such experiments, but he did not categorize the emissions as what were later called X-rays. Tesla generalized the phenomenon as radiant energy of "invisible" kinds. Tesla stated the facts of his methods concerning various experiments in his 1897 X-ray lecture before the New York Academy of Sciences. Also in this lecture, Tesla stated the method of construction and safe operation of X-ray equipment. His X-ray experimentation by vacuum high field emissions also led him to alert the scientific community to the biological hazards associated with X-ray exposure.
## Fernando Sanford
X-rays were first generated and detected by Fernando Sanford (1854-1948), the foundation Professor of Physics at Stanford University, in 1891. From 1886 to 1888 he had studied in the Hermann Helmholtz laboratory in Berlin, where he became familiar with the cathode rays generated in vacuum tubes when a voltage was applied across separate electrodes, as previously studied by Heinrich Hertz and Philipp Lenard. His letter of January 6, 1893 (describing his discovery as "electric photography") to The Physical Review was duly published and an article entitled Without Lens or Light, Photographs Taken With Plate and Object in Darkness appeared in the San Francisco Examiner.
## Heinrich Hertz
In 1892, Heinrich Hertz began experimenting and demonstrated that cathode rays could penetrate very thin metal foil (such as aluminium). Philipp Lenard, a student of Heinrich Hertz, further researched this effect. He developed a version of the cathode tube and studied the penetration by X-rays of various materials. Philipp Lenard, though, did not realize that he was producing X-rays. Hermann von Helmholtz formulated mathematical equations for X-rays. He postulated a dispersion theory before Röntgen made his discovery and announcement. It was formed on the basis of the electromagnetic theory of light (Wiedmann's Annalen, Vol. XLVIII). However, he did not work with actual X-rays.
## Wilhelm Röntgen
On November 8, 1895, Wilhelm Conrad Röntgen, a German physics professor, began observing and further documenting X-rays while experimenting with vacuum tubes. Röntgen, on December 28, 1895, wrote a preliminary report "On a new kind of ray: A preliminary communication". He submitted it to the Würzburg's Physical-Medical Society journal. This was the first formal and public recognition of the categorization of X-rays. Röntgen referred to the radiation as "X", to indicate that it was an unknown type of radiation. The name stuck, although (over Röntgen's great objections), many of his colleagues suggested calling them Röntgen rays. They are still referred to as such in many languages. Röntgen received the first Nobel Prize in Physics for his discovery.
Röntgen was working on a primitive cathode ray generator that was projected through a glass partially evacuated tube. Suddenly he noticed a faint green light against the wall. The odd thing he had noticed, was that the light from the cathode ray generator was traveling through a bunch of the materials in its way (paper, wood, and books). He then started to put various objects in front of the generator, and as he was doing this, he noticed that the outline of the bones from his hand were displayed on the wall. Röntgen said he did not know what to think and kept experimenting. Two months after his initial discovery, he published his paper translated "On a New Kind of Radiation" and gave a demonstration in 1896. Röntgen had his lab notes burned after his death, but this is a likely reconstruction by his biographers.
Rontgen discovered the medical use of X radiation when he saw a picture of his wife's hand on a photographic plate formed due to X-rays. The photograph was apparently the first ever of a human body part using X-rays.
## Thomas Edison
In 1895, Thomas Edison investigated materials' ability to fluoresce when exposed to X-rays, and found that calcium tungstate was the most effective substance. Around March 1896, the fluoroscope he developed became the standard for medical X-ray examinations. Nevertheless, Edison dropped X-ray research around 1903 after the death of Clarence Madison Dally, one of his glassblowers. Dally had a habit of testing X-ray tubes on his hands, and acquired a cancer in them so tenacious that both arms were amputated in a futile attempt to save his life.
Someone shot President William McKinley, while he was attending the 1901 Pan-American Exposition in Buffalo, New York. The individual fired twice at close range with a .32 caliber revolver. The first bullet was removed but the second remained somewhere in McKinley's stomach. McKinley survived for some time and requested that Thomas Edison rush an X-ray machine to Buffalo to find the stray bullet. McKinley died of septic shock due to bacterial infection. The X-ray machine wasn't used.
## The 20th century and beyond
Prior to the 20th century and for a short while after, x-rays were generated in cold cathode tubes. These tubes had to contain a small quantity of gas (invariably air) as a current will not flow in such a tube if they are fully evacuated. One of the problems with early x-ray tubes is that the generated x-rays caused the glass to absorb the gas and consequently the efficiency quickly falls off. Larger and more frequently used tubes were provided with a means of restoring the air. This often took the form of small side tube which contained a small piece of mica - a substance that traps comparatively large quantities of air within its structure. A small electrical heater heats the mica and causes it to release a small amount of air restoring the tube's efficiency. However the mica itself has a limited life and the restore process was consequently difficult to control.
In 1904, Sir John Ambrose Flemming invented the thermionic diode valve (tube). This used a heated cathode which permitted current to flow in a vacuum. The principle was quickly applied to x-ray tubes, and hard vacuum heated cathode x-ray tubes completely solved the problem of efficiency reduction.
Two years later, physicist Charles Barkla discovered that X-rays could be scattered by gases, and that each element had a characteristic X-ray. He won the 1917 Nobel Prize in Physics for this discovery. Max von Laue, Paul Knipping and Walter Friedrich observed for the first time the diffraction of X-rays by crystals in 1912. This discovery, along with the early works of Paul Peter Ewald, William Henry Bragg and William Lawrence Bragg gave birth to the field of X-ray crystallography. The Coolidge tube was invented the following year by William D. Coolidge which permitted continuous production of X-rays; this type of tube is still in use today.
The use of X-rays for medical purposes (to develop into the field of radiation therapy) was pioneered by Major John Hall-Edwards in Birmingham, England. In 1908, he had to have his left arm amputated owing to the spread of X-ray dermatitis.
The X-ray microscope were invented in the 1950s. The Chandra X-ray Observatory launched on July 23, 1999, has been allowing the exploration of the very violent processes in the universe which produce X-rays. Unlike visible light, which is a relatively stable view of the universe, the X-ray universe is unstable, it features stars being torn apart by black holes, galactic collisions, and novas, neutron stars that build up layers of plasma that then explode into space.
An X-ray laser device was proposed as part of the Reagan administration's Strategic Defense Initiative (SDI) in the 1980s, but the first and only test of the device (a sort of laser "blaster", or death ray, powered by a thermonuclear explosion) gave inconclusive results. For technical and political reasons, the overall project (including the X-ray laser) was de-funded (though was later revived by the second Bush administration as the National Missile Defense using different technologies). | X-rays
Editor-In-Chief: Henry A. Hoff
X-radiation (composed of X-rays, or Röntgen rays) is a form of electromagnetic radiation with a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequencies in the range 30 petahertz (PHz) to 30 exahertz (EHz) (3 × 1016 Hz to 3 × 1019 Hz) and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays. In many languages it is called Röntgen radiation after one of the first investigators of the X-rays, Wilhelm Conrad Röntgen. Röntgen had called them X-rays to signify an unknown type of radiation.[4]
X-rays are primarily used for diagnostic radiography and crystallography. As a result, the term X-ray is metonymically used to refer to a radiographic image produced using this method, in addition to the method itself. X-rays are a form of ionizing radiation and as such can be dangerous. From about 0.12 to 12 keV they are classified as soft X-rays, and from about 12 to 120 keV as hard X-rays, due to their penetrating abilities.
The distinction between X-rays and gamma rays has changed in recent decades. Originally, the electromagnetic radiation emitted by X-ray tubes had a longer wavelength than the radiation emitted by radioactive nuclei (gamma rays).[5] So older literature distinguished between X- and gamma radiation on the basis of wavelength, with radiation shorter than some arbitrary wavelength, such as 10−11 m, defined as gamma rays.[6] However, as shorter wavelength continuous spectrum "X-ray" sources such as linear accelerators and longer wavelength "gamma ray" emitters were discovered, the wavelength bands largely overlapped. The two types of radiation are now usually defined by their origin: X-rays are emitted by electrons outside the nucleus, while gamma rays are emitted by the nucleus.[5][7][8][9]
# Unit of measure and exposure
The measure of X-rays ionizing ability is called the exposure:
- The coulomb per kilogram (C/kg) is the SI unit of ionizing radiation exposure, and measures the amount of radiation required to create 1 coulomb of charge of each polarity in 1 kilogram of matter.
- The röntgen (R) is an obsolete older traditional unit of exposure, which represented the amount of radiation required to create 1 esu of charge of each polarity in 1 cubic centimeter of dry air. 1 röntgen = 2.58×10−4 C/kg
However, the effect of ionizing radiation on matter (especially living tissue) is more closely related to the amount of energy deposited rather than the charge. This is called the absorbed dose:
- The gray (Gy) which has units of (J/kg), is the SI unit of absorbed dose which is the amount of radiation required to deposit 1 joule of energy in 1 kilogram of any kind of matter.
- The rad is the (obsolete) corresponding traditional unit, equal to 0.01 J deposited per kg. 100 rad = 1 Gy.
The equivalent dose is the measure of the biological effect of radiation on human tissue. For X-rays it is equal to the absorbed dose. The rem is the traditional unit of dose equivalent. This describes the Energy delivered by <math>\gamma</math> or X-radiation (indirectly ionizing radiation) for humans. The SI counterpart is the Sievert (Sv). One Sievert is equal to 100 rem. Because the rem is a relatively large unit, typical equivalent dose is measured in millirem (mrem), or one thousandth of a rem. In microsievert (μSv) - 1/1000000 Sv -, 1 mrem equals 10 μSv.
Medical X-rays are a major source of manmade radiation exposure, accounting for 58% in the USA in 1987, but since most radiation exposure is natural (82%) it only accounts for 10% of total USA radiation exposure.[10] The average person living in the United States is exposed to approximately 150 mrem annually from background sources alone.
Reported dosage due to dental X-rays seems to vary significantly. Depending on the source, a typical dental X-ray of a human results in an exposure of perhaps, 3[11][12], 40[13], 300[14], or as many as 900[15][16] mrems (30 to 9,000 μSv).
# Medical Physics
X-rays are a type of electromagnetic radiation with wavelengths of around 10-10 meters. When medical X-rays are being produced, a thin metallic sheet is placed between the emitter and the target, effectively filtering out the lower energy (soft) X-rays. This is often placed close to the window of the X-ray tube. The resultant X-ray is said to be hard. Soft X-rays overlap the range of extreme ultraviolet. The frequency of hard X-rays is higher than that of soft X-rays, and the wavelength is shorter. Hard X-rays overlap the range of "long"-wavelength (lower energy) gamma rays, however the distinction between the two terms depends on the source of the radiation, not its wavelength; X-ray photons are generated by energetic electron processes, gamma rays by transitions within atomic nuclei.
The basic production of X-rays is by accelerating electrons in order to collide with a metal target.[18] In medical applications, this is usually tungsten or a more crack resistant alloy of rhenium (5%) and tungsten (95%), but sometimes molybdenum for more specialised applications, such as when soft X-rays are needed as in mammography. In crystallography, a copper target is most common, with cobalt often being used when fluorescence from iron content in the sample might otherwise present a problem. Here the electrons suddenly decelerate upon colliding with the metal target and if enough energy is contained within the electron it is able to knock out an electron from the inner shell of the metal atom and as a result electrons from higher energy levels then fill up the vacancy and X-ray photons are emitted. This process is extremely inefficient (~0.1%) and thus to produce reasonable flux of X-rays plenty of energy has to be wasted into heat which has to be removed. The maximum energy of the produced X-ray photon in keV is limited by the energy of the incident electron, which is equal to the voltage on the tube, so an 80 kV tube can't create higher than 80 keV X-rays. The voltages used in diagnostic X-ray tubes, and thus the highest energies of the X-rays, range from roughly 20 to 150 kV.[19]
The spectral lines generated depends on the target (anode) element used and thus are called characteristic lines. Usually these are transitions from upper shells into K shell (called K lines), into L shell (called L lines) and so on. There is also a continuum Bremsstrahlung radiation given off by the electrons as they are scattered by the strong electric field near the high-Z (proton number) nuclei. In medical diagnostic applications, the low energy (soft) X-rays are unwanted, since they are totally absorbed by the body, increasing the dose. A thin metal (often aluminum, but can be one of many X-Ray filters) sheet is placed over the window of the X-ray tube, filtering out the low energy end of the spectrum.
X-rays can detect cancer, cysts, and tumors. Due to their short wavelength, in medical applications X-rays act more like a particle than a wave. This is in contrast to their application in crystallography, where their wave-like nature is most important.
Nowadays, for many (non-medical) applications, X-ray production is achieved by synchrotrons (see synchrotron light). Its unique features are brightness many orders of magnitude greater than X-ray tubes, wide spectrum, high collimation, and linear polarization.[20]
To create a blood or artery X-ray, also called digital angiography, iodine is injected into the veins and a digitized image is created. Then, a second image is established of only the parts of the X-rayed section without iodine. The first image is subtracted then a final image is produced containing both the first and second images together. Lastly, the results are printed. The doctor or surgeon then compares the results of the angiography to a perfect angiography structure to see if there are any malfunctions.
To take an X-ray of the bones, no iodization is required. Short X-ray pulses are shot through a body at first. Next, the bones absorb the most waves because they are more dense and contain Ca which absorbs stronger than the carbon, oxygen, and nitrogen atoms of soft tissue (due to more electrons in Ca atom). The X-rays that do not get absorbed turn the photographic film from white to black, leaving a white shadow of bones on the film.
# Detectors
## Photographic plate
The detection of X-rays is based on various methods. The most commonly known methods, "Image Receptors" (IR), are a photographic plate, X-ray film in a cassette, and rare earth screens.
A photographic plate or film is used in hospitals to produce images of the internal organs and bones of a patient. They are also used in industrial radiography processes, for example, to inspect welded seams. Since photographic plates are sensitive to X-rays, they provide a convenient and easy means of recording the image. X-ray film is usually provided as pre-loaded paper cartridges with the film inside a light proof paper envelope. An additional paper coated in a thin layer of lead is often included in contact with the photographic film. The lead reflects the x-rays back through the photo film to more or less double the sensitivity of the assembly. Thus, photographic film has to be used the right way round, and is marked as such. The emulsion is frequently coated on both sides of the film or plate in order to increase the sensitivity further.
The part of the patient to be X-rayed is placed between the X-ray source and the photographic receptor to produce what is a shadow of all the internal structure of that particular part of the body being X-rayed. The X-rays are blocked by dense tissues such as bone and pass through soft tissues. Those areas where the X-rays strike the photographic receptor turn black when it is developed. So where the X-rays pass through "soft" parts of the body such as organs, muscle, and skin, the plate or film turns black. Contrast compounds, containing high atomic numbered elements such as barium or iodine, which are radiopaque, can be injected in the artery of a particular organ, or given intravenously. The contrast compounds essentially block the X-rays and hence the circulation of the organ can be more readily seen. Many years ago thorium was used as a contrast medium (Thorotrast) — this caused many people to be injured or even die from the effects of the radiation from the thorium.
Photographic plates are losing favour in many X-ray facilities because of the necessity to have processing facilities readily at hand, and because the photographic plates themselves, plus the processing chemicals are relatively expensive consumables. Silver (necessary to the radiographic and photographic industry) is a non-renewable resource. Computed (CR) and digital radiography (DR) has started to replace film. Archiving of these new technologies is also space saving for facilities. Each IR technology required a lot of exposure (to the patient). This has been reduced by the use of intensifying screens.
## Photostimulable Phosphors (PSPs)
An increasingly common method of detecting X-rays is the use of Photostimulable Luminescence (PSL), pioneered by Fuji in the 1980s. In modern hospitals a PSP plate is used in place of the photographic plate. After the plate is X-rayed, excited electrons in the phosphor material remain 'trapped' in 'colour centres' in the crystal lattice until stimulated by a laser beam passed over the plate surface. The light given off during laser stimulation is collected by a photomultiplier tube and the resulting signal is converted into a digital image by computer technology, which gives this process its common name, computed radiography (also referred to as digital radiography). The PSP plate can be used over and over again, and existing x-ray equipment requires no modification to use them.
## Geiger counter
Initially, most common detection methods were based on the ionization of gases, as in the Geiger-Müller counter: a sealed volume, usually a cylinder, with a polymer or thin metal window contains a gas, and a wire, and a high voltage is applied between the cylinder (cathode) and the wire (anode). When an X-ray photon enters the cylinder, it ionizes the gas and forms ions and electrons. Electrons accelerate toward the anode, in the process causing further ionization along their trajectory. This process, known as an avalanche, is detected as a sudden flow of current, called a "count" or "event".
Ultimately, the electrons form a virtual cathode around the anode wire drastically reducing the electric field in the outer portions of the tube. This halts the collisional ionizations and limits further growth of avalanches. As a result, all "counts" on a Geiger counter are the same size and it can give no indication as to the particle energy of the radiation, unlike the proportional counter. The intensity of the radiation is measurable by the Geiger counter as the counting-rate of the system.
In order to gain energy spectrum information a diffracting crystal may be used to first separate the different photons, the method is called wavelength dispersive X-ray spectroscopy (WDX or WDS). Position-sensitive detectors are often used in conjunction with dispersive elements. Other detection equipment may be used which are inherently energy-resolving, such as the aforementioned proportional counters. In either case, use of suitable pulse-processing (MCA) equipment allows digital spectra to be created for later analysis.
For many applications, counters are not sealed but are constantly fed with purified gas (thus reducing problems of contamination or gas aging). These are called "flow counter".
## Scintillators
Some materials such as sodium iodide (NaI) can "convert" an X-ray photon to a visible photon; an electronic detector can be built by adding a photomultiplier. These detectors are called "scintillators", filmscreens or "scintillation counters". The main advantage of using these is that an adequate image can be obtained while subjecting the patient to a much lower dose of X-rays.
## Image intensification
X-rays are also used in "real-time" procedures such as angiography or contrast studies of the hollow organs (e.g. barium enema of the small or large intestine) using fluoroscopy acquired using an X-ray image intensifier. Angioplasty, medical interventions of the arterial system, rely heavily on X-ray-sensitive contrast to identify potentially treatable lesions.
## Direct semiconductor detectors
Since the 1970s, new semiconductor detectors have been developed (silicon or germanium doped with lithium, Si(Li) or Ge(Li)). X-ray photons are converted to electron-hole pairs in the semiconductor and are collected to detect the X-rays. When the temperature is low enough (the detector is cooled by Peltier effect or even cooler liquid nitrogen), it is possible to directly determine the X-ray energy spectrum; this method is called energy dispersive X-ray spectroscopy (EDX or EDS); it is often used in small X-ray fluorescence spectrometers. These detectors are sometimes called "solid state detectors". Cadmium telluride (CdTe) and its alloy with zinc, cadmium zinc telluride detectors have an increased sensitivity, which allows lower doses of X-rays to be used.
Practical application in medical imaging didn't start taking place until the 1990s. Currently amorphous selenium is used in commercial large area flat panel X-ray detectors for mammography and chest radiography. Current research and development is focussed around pixel detectors, such as CERN's energy resolving Medipix detector.
Note: A standard semiconductor diode, such as a 1N4007, will produce a small amount of current when placed in an X-ray beam. A test device once used by Medical Imaging Service personnel was a small project box that contained several diodes of this type in series, which could be connected to an oscilloscope as a quick diagnostic.
Silicon drift detectors (SDDs), produced by conventional semiconductor fabrication, now provide a cost-effective and high resolving power radiation measurement. Unlike conventional X-ray detectors, such as Si(Li)s, they do not need to be cooled with liquid nitrogen.
## Scintillator plus semiconductor detectors (indirect detection)
With the advent of large semiconductor array detectors it has become possible to design detector systems using a scintillator screen to convert from X-rays to visible light which is then converted to electrical signals in an array detector. Indirect Flat Panel Detectors (FPDs) are in widespread use today in medical, dental, veterinary and industrial applications. A common form of these detectors is based on amorphous silicon thin film transistor (TFT)/photodiode arrays.
The array technology is a variant on the amorphous silicon TFT arrays used in many flat panel displays, like the ones in computer laptops. The array consists of a sheet of glass covered with a thin layer of silicon that is in an amorphous or disordered state. At a microscopic scale, the silicon has been imprinted with millions of transistors arranged in a highly ordered array, like the grid on a sheet of graph paper. Each of these TFTs is attached to a light-absorbing photodiode making up an individual pixel (picture element). Photons striking the photodiode are converted into two carriers of electrical charge, called electron-hole pairs. Since the number of charge carriers produced will vary with the intensity of incoming light photons, an electrical pattern is created that can be swiftly converted to a voltage and then a digital signal, which is interpreted by a computer to produce a digital image. Although silicon has outstanding electronic properties, it is not a particularly good absorber of X-ray photons. For this reason, X-rays first impinge upon scintillators made from eg. gadolinium oxysulfide or cesium iodide. The scintillator absorbs the X-rays and converts them into visible light photons that then pass onto the photodiode array.
## Visibility to the human eye
While generally considered invisible to the human eye, in special circumstances X-rays can be visible. Brandes, in an experiment a short time after Röntgen's landmark 1895 paper, reported after dark adaptation and placing his eye close to an X-ray tube, seeing a faint "blue-gray" glow which seemed to originate within the eye itself.[21] Upon hearing this, Röntgen reviewed his record books and found he too had seen the effect. When placing an X-ray tube on the opposite side of a wooden door Röntgen had noted the same blue glow, seeming to emanate from the eye itself, but thought his observations to be spurious because he only saw the effect when he used one type of tube. Later he realized that the tube which had created the effect was the only one powerful enough to make the glow plainly visible and the experiment was thereafter readily repeatable. The knowledge that X-rays are actually faintly visible to the dark-adapted naked eye has largely been forgotten today; this is probably due to the desire not to repeat what would now be seen as a recklessly dangerous and harmful experiment with ionizing radiation. It is not known what exact mechanism in the eye produces the visibility: it could be due to conventional detection (excitation of rhodopsin molecules in the retina), direct excitation of retinal nerve cells, or secondary detection via, for instance, X-ray induction of phosphorescence in the eyeball with conventional retinal detection of the secondarily produced visible light.
If the intensity of an X-ray beam is high enough, the ionization of the air will make the beam visible with a white glow. The beamline from the wiggler at the ID11 at ESRF is one example of such high intensity.[22]
# Medical uses
Since Röntgen's discovery that X-rays can identify bony structures, X-rays have been developed for their use in medical imaging. Radiology is a specialized field of medicine. Radiographers employ radiography and other techniques for diagnostic imaging. Indeed, this is probably the most common use of X-ray technology.
X-rays are especially useful in the detection of pathology of the skeletal system, but are also useful for detecting some disease processes in soft tissue. Some notable examples are the very common chest X-ray, which can be used to identify lung diseases such as pneumonia, lung cancer or pulmonary edema, and the abdominal X-ray, which can detect ileus (blockage of the intestine), free air (from visceral perforations) and free fluid (in ascites). In some cases, the use of X-rays is debatable, such as gallstones (which are rarely radiopaque) or kidney stones (which are often visible, but not always). Also, traditional plain X-rays pose very little use in the imaging of soft tissues such as the brain or muscle. Imaging alternatives for soft tissues are computed axial tomography (CAT or CT scanning), magnetic resonance imaging (MRI) or ultrasound. Since 2005, X-rays are listed as a carcinogen by the U.S. government.[23] The benefits of the X-ray investigation should be balanced with the potential hazards to the unborn fetus.[24][25]
Radiotherapy, a curative medical intervention, now used almost exclusively for cancer, employs higher energies of radiation.
The efficiency of X-ray tubes is less than 2%. Most of the energy is used to heat up the anode.
# Shielding against X-Rays
Lead is the most common shield against X-Rays because of its high density (11340 kg/m3), ease of installation and low cost. The maximum range of a high-energy photon such as an X-ray in matter is infinite - at every point in the matter traversed by the photon, there is a probability of interaction. Thus there is a very small probability of no interaction over very large distances. The shielding of photons is therefore exponential - doubling the thickness of shielding will square the shielding effect.
The following table shows the recommended thickness of lead shielding in function of X-Ray energy, from the Recommendations by the Second International Congress of Radiology.[26]
# Other uses
Notable uses of X-rays include
- X-ray crystallography in which the pattern produced by the diffraction of X-rays through the closely spaced lattice of atoms in a crystal is recorded and then analyzed to reveal the nature of that lattice. A related technique, fiber diffraction, has been most notably used by Watson and Crick to discover the double helix structure of DNA.[27]
- X-ray astronomy, which is an observational branch of astronomy, which deals with the study of X-ray emission from celestial objects.
- X-ray microscopic analysis, which uses soft X-rays to produce images of very small objects.
- X-ray fluorescence, a technique in which X-rays are generated within a specimen and detected. The outgoing energy of the X-ray can be used to identify the composition of the sample.
- Industrial radiography uses X-rays for inspection of industrial parts, particularly welds.
- Paintings are often X-rayed to reveal the underdrawing and pentimenti or alterations in the course of painting, or by later restorers. Many pigments such as lead white show well in X-ray photographs.
- Airport security luggage scanners use X-rays for inspecting the interior of luggage for security threats before loading on aircraft.
- X-ray fine art photography.
- Roentgen Stereophotogrammetry is used to track movement of bones based on the implantation of markers.
# History
Among the important early researchers in X-rays were Professor Ivan Pulyui, Sir William Crookes, Johann Wilhelm Hittorf, Eugen Goldstein, Heinrich Hertz, Philipp Lenard, Hermann von Helmholtz, Nikola Tesla, Thomas Edison, Charles Glover Barkla, Max von Laue, and Wilhelm Conrad Röntgen.
## Johann Hittorf
Physicist Johann Hittorf (1824 - 1914) observed tubes with energy rays extending from a negative electrode. These rays produced a fluorescence when they hit the glass walls of the tubes. In 1876 the effect was named "cathode rays" by Eugen Goldstein, and today are known to be streams of electrons. Later, English physicist William Crookes investigated the effects of electric currents in gases at low pressure, and constructed what is called the Crookes tube. It is a glass cylinder mostly (but not completely) evacuated, containing electrodes for discharges of a high voltage electric current. He found, when he placed unexposed photographic plates near the tube, that some of them were flawed by shadows, though he did not investigate this effect. Crookes also noted that his cathode rays caused the glass walls of his tube to glow a dull blue colour. Crookes failed to realise that it wasn't actually the cathode rays that caused the blue glow, but the low level x-rays produced when the cathode rays struck the glass. Crookes tubes created electrons by ionization of the residual air in the tube by a high DC voltage of anywhere between a few kilovolts and 100 kV. This voltage accelerated the electrons coming from the cathode to a high enough velocity that they created X-rays when they struck the anode or the glass wall of the tube. Many of the early Crookes tubes undoubtedly radiated X-rays, because early researchers noticed effects that were attributable to them.[28]
## Ivan Pulyui
In 1877 Ukranian-born Ivan Pulyui, a lecturer in experimental physics at the University of Vienna, constructed various designs of Geissler vacuum discharge tube to investigate their properties.[29] He continued his investigations when appointed professor at the Czech Technical University in Prague (Prague Polytechnic). In 1886 he found that sealed photographic plates became dark when exposed to the emanations from the tubes. Early in 1896, just a few weeks after Röntgen published his first X-ray photograph, Pulyui published high-quality x-ray images in journals in Paris and London.[29] Although Pulyui had studied with Röntgen at the University of Strasbourg in the years 1873-75, his biographer Gaida (1997) asserts that his subsequent research was conducted independently.[29]
As a result of experiments into what he called cold light Ivan Pulyui is reputed to have developed an X-ray emitting device as early as 1881. He reputedly first demonstrated an X-ray photograph of a 13-year-old boy's broken arm and an X-ray photograph of his daughter's hand with a pin lying under it. The device became known as the Pulyui lamp and was mass-produced for a period. Reputedly, Pulyui personally presented one to Wilhelm Conrad Röntgen who went on to be credited as the major developer of the technology. Pulyui published his results in a scientific paper, Luminous Electrical Matter and the Fourth State of Matter in the Notes of the Austrian Imperial Academy of Sciences (1880-1883), but expressed his ideas in an obscure manner using obsolete terminology. Pulyui did gain some recognition when the work was translated and published as a book by the Royal Society in the UK. Pulyui made many other discoveries as well. He is particularly noted for inventing a device for determining the mechanical equivalent of heat that was exhibited at the Exposition Universelle, Paris, 1878. Pulyui also participated in opening of several power plants in Austria-Hungary.
The first medical X-ray made in the United States was obtained using a discharge tube of Pulyui's design. In January 1896, on reading of Röntgen's discovery, Frank Austin of Dartmouth College tested all of the discharge tubes in the physics laboratory and found that only the Pulyui tube produced X-rays. This was a result of Pulyui's inclusion of an oblique "target" of mica, used for holding samples of fluorescent material, within the tube. On 3 February 3, 1896 Gilman Frost, professor of medicine at the college, and his brother Edwin Frost, professor of physics, exposed the wrist of Eddie McCarthy, whom Edwin had treated some weeks earlier for a fracture, to the x-rays and collected the resulting image of the broken bone on gelatin photographic plates obtained from Howard Langill, a local photographer also interested in Röntgen's work.[30]
## Nikola Tesla
In April 1887, Nikola Tesla began to investigate X-rays using high voltages and tubes of his own design, as well as Crookes tubes. From his technical publications, it is indicated that he invented and developed a special single-electrode X-ray tube [31] [32], which differed from other X-ray tubes in having no target electrode. The principle behind Tesla's device is nowadays called the Bremsstrahlung process, in which a high-energy secondary X-ray emission is produced when charged particles (such as electrons) pass through matter. By 1892, Tesla performed several such experiments, but he did not categorize the emissions as what were later called X-rays. Tesla generalized the phenomenon as radiant energy of "invisible" kinds.[33] [34] Tesla stated the facts of his methods concerning various experiments in his 1897 X-ray lecture [35] before the New York Academy of Sciences. Also in this lecture, Tesla stated the method of construction and safe operation of X-ray equipment. His X-ray experimentation by vacuum high field emissions also led him to alert the scientific community to the biological hazards associated with X-ray exposure.[36]
## Fernando Sanford
X-rays were first generated and detected by Fernando Sanford (1854-1948), the foundation Professor of Physics at Stanford University, in 1891. From 1886 to 1888 he had studied in the Hermann Helmholtz laboratory in Berlin, where he became familiar with the cathode rays generated in vacuum tubes when a voltage was applied across separate electrodes, as previously studied by Heinrich Hertz and Philipp Lenard. His letter of January 6, 1893 (describing his discovery as "electric photography") to The Physical Review was duly published and an article entitled Without Lens or Light, Photographs Taken With Plate and Object in Darkness appeared in the San Francisco Examiner.[37]
## Heinrich Hertz
In 1892, Heinrich Hertz began experimenting and demonstrated that cathode rays could penetrate very thin metal foil (such as aluminium). Philipp Lenard, a student of Heinrich Hertz, further researched this effect. He developed a version of the cathode tube[38] and studied the penetration by X-rays of various materials. Philipp Lenard, though, did not realize that he was producing X-rays. Hermann von Helmholtz formulated mathematical equations for X-rays. He postulated a dispersion theory before Röntgen made his discovery and announcement. It was formed on the basis of the electromagnetic theory of light (Wiedmann's Annalen, Vol. XLVIII). However, he did not work with actual X-rays.
## Wilhelm Röntgen
On November 8, 1895, Wilhelm Conrad Röntgen, a German physics professor, began observing and further documenting X-rays while experimenting with vacuum tubes. Röntgen, on December 28, 1895, wrote a preliminary report "On a new kind of ray: A preliminary communication". He submitted it to the Würzburg's Physical-Medical Society journal.[39] This was the first formal and public recognition of the categorization of X-rays. Röntgen referred to the radiation as "X", to indicate that it was an unknown type of radiation. The name stuck, although (over Röntgen's great objections), many of his colleagues suggested calling them Röntgen rays. They are still referred to as such in many languages. Röntgen received the first Nobel Prize in Physics for his discovery.
Röntgen was working on a primitive cathode ray generator that was projected through a glass partially evacuated tube. Suddenly he noticed a faint green light against the wall. The odd thing he had noticed, was that the light from the cathode ray generator was traveling through a bunch of the materials in its way (paper, wood, and books). He then started to put various objects in front of the generator, and as he was doing this, he noticed that the outline of the bones from his hand were displayed on the wall. Röntgen said he did not know what to think and kept experimenting. Two months after his initial discovery, he published his paper translated "On a New Kind of Radiation" and gave a demonstration in 1896. Röntgen had his lab notes burned after his death, but this is a likely reconstruction by his biographers.[40]
Rontgen discovered the medical use of X radiation when he saw a picture of his wife's hand on a photographic plate formed due to X-rays. The photograph was apparently the first ever of a human body part using X-rays.
## Thomas Edison
In 1895, Thomas Edison investigated materials' ability to fluoresce when exposed to X-rays, and found that calcium tungstate was the most effective substance. Around March 1896, the fluoroscope he developed became the standard for medical X-ray examinations. Nevertheless, Edison dropped X-ray research around 1903 after the death of Clarence Madison Dally, one of his glassblowers. Dally had a habit of testing X-ray tubes on his hands, and acquired a cancer in them so tenacious that both arms were amputated in a futile attempt to save his life.
Someone shot President William McKinley, while he was attending the 1901 Pan-American Exposition in Buffalo, New York. The individual fired twice at close range with a .32 caliber revolver. The first bullet was removed but the second remained somewhere in McKinley's stomach. McKinley survived for some time and requested that Thomas Edison rush an X-ray machine to Buffalo to find the stray bullet. McKinley died of septic shock due to bacterial infection. The X-ray machine wasn't used.[41]
## The 20th century and beyond
Prior to the 20th century and for a short while after, x-rays were generated in cold cathode tubes. These tubes had to contain a small quantity of gas (invariably air) as a current will not flow in such a tube if they are fully evacuated. One of the problems with early x-ray tubes is that the generated x-rays caused the glass to absorb the gas and consequently the efficiency quickly falls off. Larger and more frequently used tubes were provided with a means of restoring the air. This often took the form of small side tube which contained a small piece of mica - a substance that traps comparatively large quantities of air within its structure. A small electrical heater heats the mica and causes it to release a small amount of air restoring the tube's efficiency. However the mica itself has a limited life and the restore process was consequently difficult to control.
In 1904, Sir John Ambrose Flemming invented the thermionic diode valve (tube). This used a heated cathode which permitted current to flow in a vacuum. The principle was quickly applied to x-ray tubes, and hard vacuum heated cathode x-ray tubes completely solved the problem of efficiency reduction.
Two years later, physicist Charles Barkla discovered that X-rays could be scattered by gases, and that each element had a characteristic X-ray. He won the 1917 Nobel Prize in Physics for this discovery. Max von Laue, Paul Knipping and Walter Friedrich observed for the first time the diffraction of X-rays by crystals in 1912. This discovery, along with the early works of Paul Peter Ewald, William Henry Bragg and William Lawrence Bragg gave birth to the field of X-ray crystallography. The Coolidge tube was invented the following year by William D. Coolidge which permitted continuous production of X-rays; this type of tube is still in use today.
The use of X-rays for medical purposes (to develop into the field of radiation therapy) was pioneered by Major John Hall-Edwards in Birmingham, England. In 1908, he had to have his left arm amputated owing to the spread of X-ray dermatitis[1].
The X-ray microscope were invented in the 1950s. The Chandra X-ray Observatory launched on July 23, 1999, has been allowing the exploration of the very violent processes in the universe which produce X-rays. Unlike visible light, which is a relatively stable view of the universe, the X-ray universe is unstable, it features stars being torn apart by black holes, galactic collisions, and novas, neutron stars that build up layers of plasma that then explode into space.
An X-ray laser device was proposed as part of the Reagan administration's Strategic Defense Initiative (SDI) in the 1980s, but the first and only test of the device (a sort of laser "blaster", or death ray, powered by a thermonuclear explosion) gave inconclusive results. For technical and political reasons, the overall project (including the X-ray laser) was de-funded (though was later revived by the second Bush administration as the National Missile Defense using different technologies). | https://www.wikidoc.org/index.php/X-Ray | |
629380faf505355b82b941921d214af2b3644b8c | wikidoc | YME1L1 | YME1L1
ATP-dependent metalloprotease YME1L1 is an enzyme that in humans is encoded by the YME1L1 gene. YME1L1 belongs to the AAA family of ATPases and mainly functions in the maintenance of mitochondrial morphology. Mutations in this gene would cause infantile-onset mitochondriopathy.
# Structure
## Gene
The YME1L1 gene is located at chromosome 10p14, consisting of 20 exons. Two transcript variants encoding different isoforms have been found for this gene.
## Protein
YME1L1 consists of 716 amino acids and is highly similar to all mitochondrial AAA proteases and in particular to yeast Yme1p. Three different domains are identified via sequence analysis, including an AAA consensus sequence between amino acids 317 and 502, an ATP/GTP binding motif, and a HEXXH motif typical of a zinc-dependent binding domain.
# Function
YME1L1 is embedded in the inner mitochondrial membrane and is more abundant in tissues with a high content of mitochondria such as human adult heart, skeletal muscle, and pancreas RNA. YME1L1 is a member of the AAA family of ATPases and has an important role for the maintenance of mitochondrial morphology. Its mature form assembles into a homo-oligomeric complex within the inner mitochondrial membrane (IM). It degrades both intermembrane space and IM proteins, including lipid transfer proteins, components of protein translocases of the IM, and the dynamin-like GTPase optic atrophy 1 (OPA1) Loss of YME1L1 accelerates OMA1-dependent long-form OPA1 cleavage, resulting in short-form OPA1 accumulation, increased mitochondrial fission, and mitochondrial network fragmentation. It’s also reported that YME1L1 controls the accumulation of respiratory chain subunits and is required for apoptotic resistance, cristae morphogenesis, and cell proliferation.
# Clinical significance
A homozygous mutation in the YME1L1 gene would cause infantile-onset mitochondriopathy, with severe intellectual disability, muscular impairments, and optic nerve atrophy. The missense mutation affects the MPP processing site and impairs YME1L1 maturation, leading to its rapid degradation, and also leads to a proliferation defect, abnormal OPA1 processing and mitochondrial fragmentation.
# Interactions
- OPA1
- OMA1 | YME1L1
ATP-dependent metalloprotease YME1L1 is an enzyme that in humans is encoded by the YME1L1 gene.[1] YME1L1 belongs to the AAA family of ATPases and mainly functions in the maintenance of mitochondrial morphology. Mutations in this gene would cause infantile-onset mitochondriopathy.[2]
# Structure
## Gene
The YME1L1 gene is located at chromosome 10p14, consisting of 20 exons. Two transcript variants encoding different isoforms have been found for this gene.
## Protein
YME1L1 consists of 716 amino acids and is highly similar to all mitochondrial AAA proteases and in particular to yeast Yme1p. Three different domains are identified via sequence analysis, including an AAA consensus sequence between amino acids 317 and 502, an ATP/GTP binding motif, and a HEXXH motif typical of a zinc-dependent binding domain.[3]
# Function
YME1L1 is embedded in the inner mitochondrial membrane and is more abundant in tissues with a high content of mitochondria such as human adult heart, skeletal muscle, and pancreas RNA.[3][2] YME1L1 is a member of the AAA family of ATPases and has an important role for the maintenance of mitochondrial morphology.[2] Its mature form assembles into a homo-oligomeric complex within the inner mitochondrial membrane (IM).[4] It degrades both intermembrane space and IM proteins, including lipid transfer proteins, components of protein translocases of the IM, and the dynamin-like GTPase optic atrophy 1 (OPA1) [5][6][7] Loss of YME1L1 accelerates OMA1-dependent long-form OPA1 cleavage, resulting in short-form OPA1 accumulation, increased mitochondrial fission, and mitochondrial network fragmentation.[8] It’s also reported that YME1L1 controls the accumulation of respiratory chain subunits and is required for apoptotic resistance, cristae morphogenesis, and cell proliferation.[9]
# Clinical significance
A homozygous mutation in the YME1L1 gene would cause infantile-onset mitochondriopathy, with severe intellectual disability, muscular impairments, and optic nerve atrophy. The missense mutation affects the MPP processing site and impairs YME1L1 maturation, leading to its rapid degradation, and also leads to a proliferation defect, abnormal OPA1 processing and mitochondrial fragmentation.[2]
# Interactions
- OPA1 [10]
- OMA1 [6] | https://www.wikidoc.org/index.php/YME1L1 | |
8ff0942b5d2b2ffee76b70ef5e355bf2c030631d | wikidoc | Z-test | Z-test
The Z-test is a statistical test used in inference which determines if the difference between a sample mean and the population mean is large enough to be statistically significant.
# Notation and mathematics
In order for the Z-test to be reliable, certain conditions must be met. The most important is that since the Z-test uses the population mean and population standard deviation, these must be known. The sample must be a simple random sample of the population. If the sample came from a different sampling method, a different formula must be used. It must also be known that the population varies normally (i.e., the sampling distribution of the probabilities of possible values fits a standard normal curve). If it is not known that the population varies normally, it suffices to have a sufficiently large sample, generally agreed to be ≥ 30 or 40.
In actuality, knowing the true σ of a population is unrealistic except for cases such as standardized testing in which the entire population is known. In cases where it is impossible to measure every member of a population it is more realistic to use a t-test, which uses the standard error obtained from the sample along with the t-distribution.
The test requires the following to be known:
- σ (the standard deviation of the population)
- μ (the mean of the population)
- x (the mean of the sample)
- n (the size of the sample)
First calculate the standard error (SE) of the mean:
The formula for calculating the z score for the Z-test is as follows:
Finally, the z score is compared to a Z table, a table which contains the percent of area under the normal curve between the mean and the z score. Using this table will indicate whether the calculated z score is within the realm of chance or if the z score is so different from the mean that the sample mean is unlikely to have happened by chance.
The Z-test is used primarily with standardized testing to determine if the test scores of a particular sample of test takers are within or outside of the standard performance of test takers.
# Example
Let's take a look at using the Z-test with standardized testing.
In a U.S. school district, a standardized reading test is used to test the performance of fifth grade students in an elementary school against the national norm for fifth grade students. The number of fifth grade students in this elementary school taking the test is 55 students.
The national norm test score, the population mean, for this particular standardized test is 100 points. The population standard deviation for the year under study is 12.
The scores of the fifth grade students of the elementary school in this school district are a sample of the total population of fifth grade students in the U.S. which have also taken the test.
The school district is told that the mean for their particular school is 96, which is lower than the national mean. Parents of the students become upset when they learn their school is below the national norm for the reading test. The school district administration points out that the test scores are actually pretty close to the population mean though they are lower.
The real question is this, is the school's mean test score sufficiently lower than the national norm as to indicate a problem or is the school's mean test score within acceptable parameters. We will use the Z-test to see.
First of all calculate the standard error of the mean:
Next calculate the z score:
Remember that a z score is the distance from the population mean in units of the population standard deviation. This means that in our example, a mean score of 96 is −2.47 standard deviation units from the population mean. The negative means that the sample mean is less than the population mean. Since the normal curve is symmetric the Z table is always expressed in positive z scores so if the calculated z score is negative, look it up in the table as if it were non-negative.
Next we look the z score up in a Z table and we find that a z score of −2.47 is 49.32%. This means that the area under the normal curve between the population mean and our sample mean is 49.32%.
What this tells us is that 49.32% plus 50% or 99.32% of all the possible samples of students of the same size would have a higher test score mean than our sample of fifth grade students. This is because our z score is negative so we are below the population mean. So not only do we include the distance between our sample mean and the population mean, we also include the area under the normal curve which is greater than the population mean.
If our sample mean had been 104 rather than 96, then our z score would have been 2.47 which would have indicated that our sample mean was above the population mean. That would have indicated that the fifth grade students in our sample were in the top 0.7% of the nation.
But let's get back to our original question. Is there a problem with the reading program at our elementary school? Our question can be reformulated to say, is the mean from our elementary school, a sample from the general population of fifth grade students, far enough outside of the norm that we need to take a corrective action to improve the reading program?
Let's put this in the form of a hypothesis which we are going to test with our statistical analysis. Our hypothesis is that our sample mean is significantly different from the population mean and that corrective action is necessary. Our null hypothesis is that the difference is purely attributable to chance and no action is necessary.
To answer this question, we need to determine what is the level of confidence (confidence level) we want to use. Typically a 0.05 confidence level is used meaning that if the null hypothesis is true we stand only a 5% chance of rejecting it anyway.
In the case of our sample mean, the z score of −2.47 which provides us a value of 49.32% means that 49.32% plus 49.32% or 98.64% of the population scored closer to the population mean than did our sample of students.
Therefore we conclude with a 95% confidence level that the test performance of the students in our sample were not within the normal variation and that we do need to take corrective action to improve the test scores. | Z-test
The Z-test is a statistical test used in inference which determines if the difference between a sample mean and the population mean is large enough to be statistically significant.
# Notation and mathematics
In order for the Z-test to be reliable, certain conditions must be met. The most important is that since the Z-test uses the population mean and population standard deviation, these must be known. The sample must be a simple random sample of the population. If the sample came from a different sampling method, a different formula must be used. It must also be known that the population varies normally (i.e., the sampling distribution of the probabilities of possible values fits a standard normal curve). If it is not known that the population varies normally, it suffices to have a sufficiently large sample, generally agreed to be ≥ 30 or 40.
In actuality, knowing the true σ of a population is unrealistic except for cases such as standardized testing in which the entire population is known. In cases where it is impossible to measure every member of a population it is more realistic to use a t-test, which uses the standard error obtained from the sample along with the t-distribution.
The test requires the following to be known:
- σ (the standard deviation of the population)
- μ (the mean of the population)
- x (the mean of the sample)
- n (the size of the sample)
First calculate the standard error (SE) of the mean:
The formula for calculating the z score for the Z-test is as follows:
Finally, the z score is compared to a Z table, a table which contains the percent of area under the normal curve between the mean and the z score. Using this table will indicate whether the calculated z score is within the realm of chance or if the z score is so different from the mean that the sample mean is unlikely to have happened by chance.
The Z-test is used primarily with standardized testing to determine if the test scores of a particular sample of test takers are within or outside of the standard performance of test takers.
# Example
Let's take a look at using the Z-test with standardized testing.
In a U.S. school district, a standardized reading test is used to test the performance of fifth grade students in an elementary school against the national norm for fifth grade students. The number of fifth grade students in this elementary school taking the test is 55 students.
The national norm test score, the population mean, for this particular standardized test is 100 points. The population standard deviation for the year under study is 12.
The scores of the fifth grade students of the elementary school in this school district are a sample of the total population of fifth grade students in the U.S. which have also taken the test.
The school district is told that the mean for their particular school is 96, which is lower than the national mean. Parents of the students become upset when they learn their school is below the national norm for the reading test. The school district administration points out that the test scores are actually pretty close to the population mean though they are lower.
The real question is this, is the school's mean test score sufficiently lower than the national norm as to indicate a problem or is the school's mean test score within acceptable parameters. We will use the Z-test to see.
First of all calculate the standard error of the mean:
Next calculate the z score:
Remember that a z score is the distance from the population mean in units of the population standard deviation. This means that in our example, a mean score of 96 is −2.47 standard deviation units from the population mean. The negative means that the sample mean is less than the population mean. Since the normal curve is symmetric the Z table is always expressed in positive z scores so if the calculated z score is negative, look it up in the table as if it were non-negative.
Next we look the z score up in a Z table and we find that a z score of −2.47 is 49.32%. This means that the area under the normal curve between the population mean and our sample mean is 49.32%.
What this tells us is that 49.32% plus 50% or 99.32% of all the possible samples of students of the same size would have a higher test score mean than our sample of fifth grade students. This is because our z score is negative so we are below the population mean. So not only do we include the distance between our sample mean and the population mean, we also include the area under the normal curve which is greater than the population mean.
If our sample mean had been 104 rather than 96, then our z score would have been 2.47 which would have indicated that our sample mean was above the population mean. That would have indicated that the fifth grade students in our sample were in the top 0.7% of the nation.
But let's get back to our original question. Is there a problem with the reading program at our elementary school? Our question can be reformulated to say, is the mean from our elementary school, a sample from the general population of fifth grade students, far enough outside of the norm that we need to take a corrective action to improve the reading program?
Let's put this in the form of a hypothesis which we are going to test with our statistical analysis. Our hypothesis is that our sample mean is significantly different from the population mean and that corrective action is necessary. Our null hypothesis is that the difference is purely attributable to chance and no action is necessary.
To answer this question, we need to determine what is the level of confidence (confidence level) we want to use. Typically a 0.05 confidence level is used meaning that if the null hypothesis is true we stand only a 5% chance of rejecting it anyway.
In the case of our sample mean, the z score of −2.47 which provides us a value of 49.32% means that 49.32% plus 49.32% or 98.64% of the population scored closer to the population mean than did our sample of students.
Therefore we conclude with a 95% confidence level that the test performance of the students in our sample were not within the normal variation and that we do need to take corrective action to improve the test scores.
# External links
- Code/pseudo-code for Z-test at Google Groups
- http://espse.ed.psu.edu/statistics/Chapters/Chapter6/Chap6.html | https://www.wikidoc.org/index.php/Z-test | |
6d2c0e48f3b13e0e736ac2954ea1dda8286a5134 | wikidoc | ZBTB32 | ZBTB32
Zinc finger and BTB domain-containing protein 32 is a protein that in humans is encoded by the 1960 bp ZBTB32 gene. The 52 kDa protein (487 aa) is a transcriptional repressor and the gene is expressed in T and B cells upon activation, but also significantly in testis cells. It is a member of the Poxviruses and Zinc-finger (POZ) and Krüppel (POK) family of proteins, and was identified in multiple screens involving either immune cell tumorigenesis or immune cell development.
The protein recruits histone modification enzymes to chromatin to affect gene activation. ZBTB32 recruits corepressors, such as N-CoR and HDACs to its target genes, induces repressive chromatin states and acts cooperatively with other proteins, e.g. with Blimp-1, to suppress the transcription of genes .
It contains a N-terminal BTB/POZ domain (IPR000210) or a SKP1/BTB/POZ domain (IPR011333), and three C-terminal zinc fingers, Znf_C2H2_sf. (IPR036236), Znf_C2H2_type domain (IPR013087), a Znf_RING/FYVE/PHD domain (IPR013083), followed by a putative UBZ4 domain.
# Nomenclature
Zinc finger and BTB domain-containing protein 32 is also known as:
- Fanconi Anemia Zinc Finger Protein (FAZF),
- Testis Zinc Finger Protein (TZFP),
- FANCC-Interacting Protein (FAXP),
- Zinc Finger Protein 538 (ZNF538),
- Repressor of GATA3 (ROG),
- PLZF (Promyelocytic Leukemia Zinc Finger and Zbtb16)-like zinc finger protein (PLZP)
# Interactions
Zbtb32 has been shown to interact with:
- Fanconi anemia complementation group C (Fancc)
- Thioredoxin interacting protein (Txnip), but the interaction might be unspecific; however, Vitamin D3 upregulated protein 1 (VDUP1) seems to interact, and
- Zinc finger and BTB domain-containing protein 16 (Zbtb16)
- Zinc-finger elbow-related proline domain protein 2 (Zpo2).
- GATA binding protein (Gata2)
# Immune system
The expression of ZBTB32 is induced by inflammatory cytokines and promotes proliferation of natural killer cells.
Zbtb32 knockout mice show a trend to develop type 1 diabetes, although the difference is not statistically different. Furthermore the Zbtb32 do not show a difference in lymphocyte proliferation, possibly due to compensation from other genes.
# Cancer
ZBTB32 is highly expressed spermatogonial stem cells, in hematopoietic stem and progenitor cells (please also refer to the RNA expression pattern to the right), in diffuse large B-cell lymphoma (DLBCL) and appears to suppress the immune system by silencing the CIITA gene.
The transcription factor gene GATA3 is altered in mammary tumors. Down-regulation of GATA3 expression and activity by the Zinc-finger elbow-related proline domain protein 2 (Zpo2), whereas Zbtb32 facilitates Zpo2 targeting to the GATA3 promoter, results in the development of aggressive breast cancers.
A DNA methylation correlation network was built based on the methylation correlation between differentially methylated genes. A survival analysis of candidate biomarkers was performed. One of eight biomarkers and hub genes identified
in colon cancer is ZBTB32.
The expression of Zbtb32 is upregulated after exposure to cisplatin. | ZBTB32
Zinc finger and BTB domain-containing protein 32 is a protein that in humans is encoded by the 1960 bp ZBTB32 gene. The 52 kDa protein (487 aa) is a transcriptional repressor and the gene is expressed in T and B cells upon activation, but also significantly in testis cells. It is a member of the Poxviruses and Zinc-finger (POZ) and Krüppel (POK) family of proteins,[1][2] and was identified in multiple screens involving either immune cell tumorigenesis or immune cell development.
The protein recruits histone modification enzymes to chromatin to affect gene activation.[3] ZBTB32 recruits corepressors, such as N-CoR and HDACs to its target genes, induces repressive chromatin states and acts cooperatively with other proteins, e.g. with Blimp-1,[3] to suppress the transcription of genes .[3]
It contains a N-terminal BTB/POZ domain (IPR000210) or a SKP1/BTB/POZ domain (IPR011333), and three C-terminal zinc fingers, Znf_C2H2_sf. (IPR036236), Znf_C2H2_type domain (IPR013087), a Znf_RING/FYVE/PHD domain (IPR013083), followed by a putative UBZ4 domain.[4]
# Nomenclature
Zinc finger and BTB domain-containing protein 32 is also known as:
- Fanconi Anemia Zinc Finger Protein (FAZF),
- Testis Zinc Finger Protein (TZFP),
- FANCC-Interacting Protein (FAXP),
- Zinc Finger Protein 538 (ZNF538),
- Repressor of GATA3 (ROG),
- PLZF (Promyelocytic Leukemia Zinc Finger and Zbtb16)-like zinc finger protein (PLZP)
# Interactions
Zbtb32 has been shown to interact with:
- Fanconi anemia complementation group C (Fancc)[5][6]
- Thioredoxin interacting protein (Txnip), but the interaction might be unspecific; however, Vitamin D3 upregulated protein 1 (VDUP1) seems to interact,[7] and
- Zinc finger and BTB domain-containing protein 16 (Zbtb16)[1]
- Zinc-finger elbow-related proline domain protein 2 (Zpo2).[8]
- GATA binding protein (Gata2)[9]
# Immune system
The expression of ZBTB32 is induced by inflammatory cytokines and promotes proliferation of natural killer cells.[10]
Zbtb32 knockout mice show a trend to develop type 1 diabetes, although the difference is not statistically different. Furthermore the Zbtb32 do not show a difference in lymphocyte proliferation, possibly due to compensation from other genes.[11]
# Cancer
ZBTB32 is highly expressed spermatogonial stem cells, in hematopoietic stem and progenitor cells (please also refer to the RNA expression pattern to the right), in diffuse large B-cell lymphoma (DLBCL) and appears to suppress the immune system by silencing the CIITA gene.[12]
The transcription factor gene GATA3 is altered in mammary tumors. Down-regulation of GATA3 expression and activity by the Zinc-finger elbow-related proline domain protein 2 (Zpo2), whereas Zbtb32 facilitates Zpo2 targeting to the GATA3 promoter, results in the development of aggressive breast cancers.[8]
A DNA methylation correlation network was built based on the methylation correlation between differentially methylated genes. A survival analysis of candidate biomarkers was performed. One of eight biomarkers and hub genes identified
in colon cancer is ZBTB32.[13]
The expression of Zbtb32 is upregulated after exposure to cisplatin.[14] | https://www.wikidoc.org/index.php/ZBTB32 | |
c559328a20ca6f9dff3ee8442c79ccfb9932f3d5 | wikidoc | ZC3HC1 | ZC3HC1
Nuclear-interacting partner of ALK (NIPA), also known as zinc finger C3HC-type protein 1 (ZC3HC1), is a protein that in humans is encoded by the ZC3HC1 gene on chromosome 7. It is ubiquitously expressed in many tissues and cell types though exclusively expressed in the nuclear subcellular location. NIPA is a skp1 cullin F-box (SCF)-type ubiquitin E3 ligase (SCFNIPA) complex protein involved in regulating entry into mitosis. The ZC3HC1 gene also contains one of 27 SNPs associated with increased risk of coronary artery disease.
# Structure
## Gene
The ZC3HC1 gene resides on chromosome 7 at the band 7q32.2 and includes 14 exons.
## Protein
NIPA is a 60-kDa E3 ligase that contains one C3HC-type zinc finger and one F-box-like region. Moreover, a 50-residue region (amino acids 352-402) at its C-terminal serves as the nuclear translocation signal (NLS sequence) while a 96-residue region (amino acids 306-402) is proposed to serve as the phosphotyrosine-binding domain. NIPA is one component of the nuclear SCFNIPA complex, and phosphorylation of NIPA at three serine residues, Ser-354, Ser-359 and Ser-395, has been demonstrated to inactivate the complex as a whole.
# Function
NIPA is broadly expressed in the human tissues, with the highest expression in heart, skeletal muscle, and testis. It is a human F-box protein that defines an SCF-type ubiquitin E3 ligase, the formation of which is regulated by cell-cycle-dependent phosphorylation of NIPA. Cyclin B1, essential in the entry into mitosis, is targeted by SCFNIPA in interphase. Phosphorylation of NIPA occurs in G2 phase, results in dissociation of NIPA from the SCF core, and has been proven critical for proper G2/M transition. Oscillating ubiquitination of nuclear cyclin B1 driven by the SCFNIPA complex contributes to the timing of mitotic entry. NIPA is also reported to delay apoptosis and the localization of NIPA is required for this antiapoptotic function.
# Model organisms
Model organisms have been used in the study of ZC3HC1 function. A conditional knockout mouse line, called Zc3hc1tm1a(KOMP)Wtsi was generated as part of the International Knockout Mouse Consortium program — a high-throughput mutagenesis project to generate and distribute animal models of disease to interested scientists.
Male and female animals underwent a standardized phenotypic screen to determine the effects of deletion. Twenty two tests were carried out on mutant mice and eleven significant abnormalities were observed. Fewer than expected homozygous mutant mice were identified at weaning. Mutants appear to be subfertile, had decreased vertical activity in an open field, decreased lean body mass, decreased rib number and decreased mature B cell number. Males also had a decreased body weight, an abnormal posture and atypical indirect calorimetry data. Females also had an abnormally short snout and atypical haematology parameters .
# Clinical relevance
In humans, NIPA has been implicated in cardiovascular diseases by genome-wide association (GWAS) studies. Specifically, a single-nucleotide polymorphism (SNP) situated in ZC3HC1 has been shown to predict coronary artery disease. This prediction appears to be independent of traditional risk factors for cardiovascular disease such as high cholesterol levels, high blood pressure, obesity, smoking and diabetes mellitus, which are primary targets of current treatments for coronary artery disease. Therefore, studying the function of this gene may identify novel pathways contributing to coronary artery disease that result in the development of novel therapeutics.
## Clinical marker
At the coronary artery disease-associated locus 7q32.2, only a single SNP (rs11556924) is associated with coronary artery disease risk, with no other variants in strong linkage disequilibrium. The rs11556924 SNP in the ZC3HC1 gene results in an arginine-histidine polymorphism at amino acid residue 363 in NIPA. Furthermore, rs11556924 has also been associated with altered carotid intima-media thickness in patients with rheumatoid arthritis and with altered risk of atrial fibrillation.
Additionally, a multi-locus genetic risk score study based on a combination of 27 loci, including the ZC3HC1 gene, identified individuals at increased risk for both incident and recurrent coronary artery disease events, as well as an enhanced clinical benefit from statin therapy. The study was based on a community cohort study (the Malmo Diet and Cancer study) and four additional randomized controlled trials of primary prevention cohorts (JUPITER and ASCOT) and secondary prevention cohorts (CARE and PROVE IT-TIMI 22). | ZC3HC1
Nuclear-interacting partner of ALK (NIPA), also known as zinc finger C3HC-type protein 1 (ZC3HC1), is a protein that in humans is encoded by the ZC3HC1 gene on chromosome 7.[1][2] It is ubiquitously expressed in many tissues and cell types though exclusively expressed in the nuclear subcellular location.[3][4] NIPA is a skp1 cullin F-box (SCF)-type ubiquitin E3 ligase (SCFNIPA) complex protein involved in regulating entry into mitosis.[5] The ZC3HC1 gene also contains one of 27 SNPs associated with increased risk of coronary artery disease.[6]
# Structure
## Gene
The ZC3HC1 gene resides on chromosome 7 at the band 7q32.2 and includes 14 exons.[2]
## Protein
NIPA is a 60-kDa E3 ligase that contains one C3HC-type zinc finger and one F-box-like region.[7][8][8][9] Moreover, a 50-residue region (amino acids 352-402) at its C-terminal serves as the nuclear translocation signal (NLS sequence) while a 96-residue region (amino acids 306-402) is proposed to serve as the phosphotyrosine-binding domain.[5][7] NIPA is one component of the nuclear SCFNIPA complex, and phosphorylation of NIPA at three serine residues, Ser-354, Ser-359 and Ser-395, has been demonstrated to inactivate the complex as a whole.[5]
# Function
NIPA is broadly expressed in the human tissues, with the highest expression in heart, skeletal muscle, and testis.[7] It is a human F-box protein that defines an SCF-type ubiquitin E3 ligase, the formation of which is regulated by cell-cycle-dependent phosphorylation of NIPA. Cyclin B1, essential in the entry into mitosis, is targeted by SCFNIPA in interphase. Phosphorylation of NIPA occurs in G2 phase, results in dissociation of NIPA from the SCF core, and has been proven critical for proper G2/M transition.[4] Oscillating ubiquitination of nuclear cyclin B1 driven by the SCFNIPA complex contributes to the timing of mitotic entry.[5][10] NIPA is also reported to delay apoptosis and the localization of NIPA is required for this antiapoptotic function.[7]
# Model organisms
Model organisms have been used in the study of ZC3HC1 function. A conditional knockout mouse line, called Zc3hc1tm1a(KOMP)Wtsi[24][25] was generated as part of the International Knockout Mouse Consortium program — a high-throughput mutagenesis project to generate and distribute animal models of disease to interested scientists.[26][27][28]
Male and female animals underwent a standardized phenotypic screen to determine the effects of deletion.[22][29] Twenty two tests were carried out on mutant mice and eleven significant abnormalities were observed.[22] Fewer than expected homozygous mutant mice were identified at weaning. Mutants appear to be subfertile, had decreased vertical activity in an open field, decreased lean body mass, decreased rib number and decreased mature B cell number. Males also had a decreased body weight, an abnormal posture and atypical indirect calorimetry data. Females also had an abnormally short snout and atypical haematology parameters .[22]
# Clinical relevance
In humans, NIPA has been implicated in cardiovascular diseases by genome-wide association (GWAS) studies. Specifically, a single-nucleotide polymorphism (SNP) situated in ZC3HC1 has been shown to predict coronary artery disease.[30][31] This prediction appears to be independent of traditional risk factors for cardiovascular disease such as high cholesterol levels, high blood pressure, obesity, smoking and diabetes mellitus, which are primary targets of current treatments for coronary artery disease. Therefore, studying the function of this gene may identify novel pathways contributing to coronary artery disease that result in the development of novel therapeutics.
## Clinical marker
At the coronary artery disease-associated locus 7q32.2, only a single SNP (rs11556924) is associated with coronary artery disease risk, with no other variants in strong linkage disequilibrium. The rs11556924 SNP in the ZC3HC1 gene results in an arginine-histidine polymorphism at amino acid residue 363 in NIPA.[32] Furthermore, rs11556924 has also been associated with altered carotid intima-media thickness in patients with rheumatoid arthritis[33] and with altered risk of atrial fibrillation.[34]
Additionally, a multi-locus genetic risk score study based on a combination of 27 loci, including the ZC3HC1 gene, identified individuals at increased risk for both incident and recurrent coronary artery disease events, as well as an enhanced clinical benefit from statin therapy. The study was based on a community cohort study (the Malmo Diet and Cancer study) and four additional randomized controlled trials of primary prevention cohorts (JUPITER and ASCOT) and secondary prevention cohorts (CARE and PROVE IT-TIMI 22).[6] | https://www.wikidoc.org/index.php/ZC3HC1 | |
fda4dd92f0b2e7bc5599bb04d1a90c5fd3a0488a | wikidoc | ZCCHC6 | ZCCHC6
Terminal uridylyltransferase 7 (TUT7), also known as "zinc finger, CCHC domain containing 6", is an enzyme that in humans is encoded by the ZCCHC6 gene located on chromosone 9. The ZCCHC6 protein mediates the terminal uridylation of RNA transcripts with short poly-A tails and is involved in mRNA and microRNA degradation
# Structure
The ZCCHC6 gene contains 33 exons with at least six known isoforms due to alternative splicing. The ZCCHC6 gene encodes for a protein that is 171 kDa in molecular weight and is localized to the cytoplasm.
# Function
It catalyzes the following reaction, requiring Mg2+ and Mn2+ as co-factors.
UTP + RNA(n) = diphosphate + RNA(n+1)
Uridylation catalyzed by ZCCHC6 takes place readily on deadenylated mRNAs inside the cells. Purified ZZHC6 selectively recognizes and uridylates RNA molecules possessing short polyA-tails (less than 25 nucleotides) in vitro. In cells depleted of ZCCHC6, the majority of mRNAs lose the signature oligo-U-tails that are characteristic of ZCCHC6 reactivity, and the half-life of mRNA molecules are accordingly prolonged.
In addition to mRNA degradation, uridylation is also thought to function in pre-microRNA maturation, with some group II pre-microRNA requiring 3' mono-uridylation for Dicer processing. ZCCHC6 is thought to work in redundancy with ZCCHC11 to mediate the biogenesis of the let-7 microRNA through uridylation. | ZCCHC6
Terminal uridylyltransferase 7 (TUT7), also known as "zinc finger, CCHC domain containing 6", is an enzyme that in humans is encoded by the ZCCHC6 gene located on chromosone 9.[1][2] The ZCCHC6 protein mediates the terminal uridylation of RNA transcripts with short poly-A tails and is involved in mRNA and microRNA degradation
# Structure
The ZCCHC6 gene contains 33 exons with at least six known isoforms due to alternative splicing. The ZCCHC6 gene encodes for a protein that is 171 kDa in molecular weight and is localized to the cytoplasm.
# Function
It catalyzes the following reaction, requiring Mg2+ and Mn2+ as co-factors.
UTP + RNA(n) = diphosphate + RNA(n+1) [3]
Uridylation catalyzed by ZCCHC6 takes place readily on deadenylated mRNAs inside the cells.[4] Purified ZZHC6 selectively recognizes and uridylates RNA molecules possessing short polyA-tails (less than 25 nucleotides) in vitro. In cells depleted of ZCCHC6, the majority of mRNAs lose the signature oligo-U-tails that are characteristic of ZCCHC6 reactivity, and the half-life of mRNA molecules are accordingly prolonged.[4]
In addition to mRNA degradation, uridylation is also thought to function in pre-microRNA maturation, with some group II pre-microRNA requiring 3' mono-uridylation for Dicer processing.[5] ZCCHC6 is thought to work in redundancy with ZCCHC11 to mediate the biogenesis of the let-7 microRNA through uridylation.[6] | https://www.wikidoc.org/index.php/ZCCHC6 | |
9b73a4dc3ad8d7ba6ee4d25e47c94167bf9ce333 | wikidoc | ZFYVE1 | ZFYVE1
Zinc finger FYVE domain-containing protein 1 is a protein that in humans is encoded by the ZFYVE1 gene.
The FYVE domain mediates the recruitment of proteins involved in membrane trafficking and cell signaling to phosphatidylinositol 3-phosphate (PtdIns(3)P)-containing membranes. This gene encodes a protein which contains two zinc-binding FYVE domains in tandem. This protein displays a predominantly Golgi, endoplasmic reticulum and vesicular distribution.
Alternatively spliced transcript variants have been found for this gene, and they encode two isoforms with different sizes. | ZFYVE1
Zinc finger FYVE domain-containing protein 1 is a protein that in humans is encoded by the ZFYVE1 gene.[1][2][3]
The FYVE domain mediates the recruitment of proteins involved in membrane trafficking and cell signaling to phosphatidylinositol 3-phosphate (PtdIns(3)P)-containing membranes. This gene encodes a protein which contains two zinc-binding FYVE domains in tandem. This protein displays a predominantly Golgi, endoplasmic reticulum and vesicular distribution.
Alternatively spliced transcript variants have been found for this gene, and they encode two isoforms with different sizes.[3] | https://www.wikidoc.org/index.php/ZFYVE1 | |
b491798a56ab48f5a20515d6bac2ccbb68b364b1 | wikidoc | ZMYND8 | ZMYND8
Protein kinase C-binding protein 1 is an enzyme that in humans is encoded by the ZMYND8 gene.
The protein encoded by this gene is a receptor for activated C-kinase (RACK) protein. The encoded protein has been shown to bind in vitro to activated protein kinase C beta I. In addition, this protein is a cutaneous T-cell lymphoma-associated antigen. Finally, the protein contains a bromodomain and two zinc fingers, and is thought to be a transcriptional regulator. Multiple transcript variants encoding several different isoforms have been found for this gene.
# Model organisms
Model organisms have been used in the study of ZMYND8 function. A conditional knockout mouse line, called Zmynd8tm1a(EUCOMM)Wtsi was generated as part of the International Knockout Mouse Consortium program — a high-throughput mutagenesis project to generate and distribute animal models of disease to interested scientists.
Male and female animals underwent a standardized phenotypic screen to determine the effects of deletion. Twenty one tests were carried out on mutant mice and two significant abnormalities were observed. Few homozygous mutant embryos were identified during gestation and none survived until weaning. The remaining tests were carried out on heterozygous mutant adult mice; no additional significant abnormalities were observed in these animals. | ZMYND8
Protein kinase C-binding protein 1 is an enzyme that in humans is encoded by the ZMYND8 gene.[1]
The protein encoded by this gene is a receptor for activated C-kinase (RACK) protein. The encoded protein has been shown to bind in vitro to activated protein kinase C beta I. In addition, this protein is a cutaneous T-cell lymphoma-associated antigen. Finally, the protein contains a bromodomain and two zinc fingers, and is thought to be a transcriptional regulator. Multiple transcript variants encoding several different isoforms have been found for this gene.[1]
# Model organisms
Model organisms have been used in the study of ZMYND8 function. A conditional knockout mouse line, called Zmynd8tm1a(EUCOMM)Wtsi[4][5] was generated as part of the International Knockout Mouse Consortium program — a high-throughput mutagenesis project to generate and distribute animal models of disease to interested scientists.[6][7][8]
Male and female animals underwent a standardized phenotypic screen to determine the effects of deletion.[2][9] Twenty one tests were carried out on mutant mice and two significant abnormalities were observed.[2] Few homozygous mutant embryos were identified during gestation and none survived until weaning. The remaining tests were carried out on heterozygous mutant adult mice; no additional significant abnormalities were observed in these animals.[2] | https://www.wikidoc.org/index.php/ZMYND8 | |
614bc570d89fd2fa7f5ab55e05df2798d7f5b170 | wikidoc | ZNF184 | ZNF184
Zinc finger protein 184, also known as ZNF184, is a protein that in humans is encoded by the ZNF184 gene on chromosome 6. It was first identified by Goldwurm et al. in 1996.
The National Center for Biotechnology Information (NCBI) Gene database entry for ZNF184 identifies conserved domains KRAB_A (Krüppel associated box) near the N-terminus and Zn-finger (Zinc finger) at the C-terminus of the translated protein. The former is associated with transcription repression and the latter with DNA binding (see Zinc finger).
# Domains and Structure
The figure below is a reformatted and annotated conceptual translation display of ZNF184's Consensus CDS. CCDS displays exons in alternating black and blue font, with red indicating a residue coded across a splice boundary.
ZNF184 has 19 zinc finger motifs at the end of its final and longest exon. The figure shows regularity among the fingers in this protein, including the 2 columns of green-highlighted Cysteine residues and the 2 columns of blue-highlighted His residues which are the reason this type of zinc finger is called C2H2. Light grey highlighted columns (one with all F; one with mostly L, and F substitutions) are highly conserved hydrophobic residues within the zinc finger motif. The other light grey highlighted column (mostly K, with a similar R substitution) is an example of fairly strong conservation in the coil sections connecting adjacent fingers.
Near the N-terminus is a KRAB_A domain followed by a KRAB_B domain. KRAB_A has a shorter α-Helix followed by a longer α-Helix. The KRAB_A motif in a zinc finger protein is known to bind with a KAP-1 protein (aka TRIM28) to accomplish a transcription repressor function, however a gene so regulated by ZNF184 has yet to be identified. The length-11 finger helices are indicated, as well as the overlapping 7-residue section in each finger which binds targeted DNA (if the finger is functioning). | ZNF184
Zinc finger protein 184, also known as ZNF184, is a protein that in humans is encoded by the ZNF184 gene[1] on chromosome 6. It was first identified by Goldwurm et al. in 1996.[2]
The National Center for Biotechnology Information (NCBI) Gene database entry[1] for ZNF184 identifies conserved domains KRAB_A (Krüppel associated box) near the N-terminus and Zn-finger (Zinc finger) at the C-terminus of the translated protein. The former is associated with transcription repression[3] and the latter with DNA binding (see Zinc finger).
# Domains and Structure
The figure below is a reformatted and annotated conceptual translation display of ZNF184's Consensus CDS.[4] CCDS displays exons in alternating black and blue font, with red indicating a residue coded across a splice boundary.
ZNF184 has 19 zinc finger motifs at the end of its final and longest exon. The figure shows regularity among the fingers in this protein, including the 2 columns of green-highlighted Cysteine residues and the 2 columns of blue-highlighted His residues which are the reason this type of zinc finger is called C2H2. Light grey highlighted columns (one with all F; one with mostly L, and F substitutions) are highly conserved hydrophobic residues within the zinc finger motif. The other light grey highlighted column (mostly K, with a similar R substitution) is an example of fairly strong conservation in the coil sections connecting adjacent fingers.
Near the N-terminus is a KRAB_A domain followed by a KRAB_B domain. KRAB_A has a shorter α-Helix followed by a longer α-Helix. The KRAB_A motif in a zinc finger protein is known to bind with a KAP-1 protein (aka TRIM28) to accomplish a transcription repressor function, however a gene so regulated by ZNF184 has yet to be identified. The length-11 finger helices are indicated, as well as the overlapping 7-residue section in each finger which binds targeted DNA (if the finger is functioning). | https://www.wikidoc.org/index.php/ZNF184 | |
0bc8b7aad832d10c719b4870190733f742c63b19 | wikidoc | ZNF366 | ZNF366
Zinc finger protein 366, also known as DC-SCRIPT (Dendritic cell-specific transcript), is a protein that in humans is encoded by the ZNF366 gene. The ZNF366 gene was first identified in a DNA comparison study between 85 kb of Fugu rubripes sequence containing 17 genes with its homologous loci in the human draft genome.
# Function
In 2006, DC-SCRIPT was isolated and characterized in human monocyte-derived dendritic cells (mo-DCs).
DC-SCRIPT contains a DNA-binding domain (11 C2H2 zinc (Zn) fingers), flanked by a proline-rich and an acidic region, which can interact with C-terminal-binding protein 1 (CtBP1), a global corepressor. In the immune system of both mice and humans, DC-SCRIPT was found to be specifically expressed in dendritic cells (DCs).
In COS-1 cells, DC-SCRIPT was shown to interact with the estrogen receptor DNA-binding domain (ERDBD) and represses ER activity through the association with RIP140, CtBP and histone deacetylases.
# Breast cancer
In 2010, it was shown that DC-SCRIPT can act as a coregulator of multiple nuclear receptors having opposite effects on type I vs type II NRs. DC-SCRIPT is able to repress ER and PR mediated transcription, whereas it can activate transcription mediated by RAR and PPAR. In the same study, it was shown that breast tumor tissue expresses lower levels of DC-SCRIPT than normal breast tissue from the same patient and that DC-SCRIPT mRNA expression is an independent prognostic factor for good survival of breast cancer patients with estrogen receptor- and/or progesterone receptor-positive tumors. | ZNF366
Zinc finger protein 366, also known as DC-SCRIPT (Dendritic cell-specific transcript), is a protein that in humans is encoded by the ZNF366 gene.[1] The ZNF366 gene was first identified in a DNA comparison study between 85 kb of Fugu rubripes sequence containing 17 genes with its homologous loci in the human draft genome.[2]
# Function
In 2006, DC-SCRIPT was isolated and characterized in human monocyte-derived dendritic cells (mo-DCs).[3]
DC-SCRIPT contains a DNA-binding domain (11 C2H2 zinc (Zn) fingers), flanked by a proline-rich and an acidic region, which can interact with C-terminal-binding protein 1 (CtBP1), a global corepressor. In the immune system of both mice and humans, DC-SCRIPT was found to be specifically expressed in dendritic cells (DCs).[4]
In COS-1 cells, DC-SCRIPT was shown to interact with the estrogen receptor DNA-binding domain (ERDBD) and represses ER activity through the association with RIP140, CtBP and histone deacetylases.[5]
# Breast cancer
In 2010, it was shown that DC-SCRIPT can act as a coregulator of multiple nuclear receptors having opposite effects on type I vs type II NRs. DC-SCRIPT is able to repress ER and PR mediated transcription, whereas it can activate transcription mediated by RAR and PPAR. In the same study, it was shown that breast tumor tissue expresses lower levels of DC-SCRIPT than normal breast tissue from the same patient and that DC-SCRIPT mRNA expression is an independent prognostic factor for good survival of breast cancer patients with estrogen receptor- and/or progesterone receptor-positive tumors.[6] | https://www.wikidoc.org/index.php/ZNF366 | |
186242143125af38076d0261b0371c8f63f59e5f | wikidoc | ZNF384 | ZNF384
Zinc finger protein 384 is a protein that in humans is encoded by the ZNF384 gene.
# Function
This gene encodes a C2H2-type zinc finger protein, which may function as a transcription factor. This gene also contains long CAG trinucleotide repeats that encode consecutive glutamine residues. The protein appears to bind and regulate the promoters of the extracellular matrix genes MMP1, MMP3, MMP7 and COL1A1. Studies in mouse suggest that ZNF384 may be part of a general mechanical pathway that couples cell construction and function during extracellular matrix remodeling. Alternative splicing results in multiple transcript variants.
# Clinical significance
Recurrent rearrangements of this gene with the Ewing's sarcoma gene, EWSR1 on chromosome 22, or with the TAF15 gene on chromosome 17, or with the TCF3 (E2A) gene on chromosome 19, have been observed in acute leukemia. | ZNF384
Zinc finger protein 384 is a protein that in humans is encoded by the ZNF384 gene.[1][2][3]
# Function
This gene encodes a C2H2-type zinc finger protein, which may function as a transcription factor. This gene also contains long CAG trinucleotide repeats that encode consecutive glutamine residues. The protein appears to bind and regulate the promoters of the extracellular matrix genes MMP1, MMP3, MMP7 and COL1A1. Studies in mouse suggest that ZNF384 may be part of a general mechanical pathway that couples cell construction and function during extracellular matrix remodeling. Alternative splicing results in multiple transcript variants.[3]
# Clinical significance
Recurrent rearrangements of this gene with the Ewing's sarcoma gene, EWSR1 on chromosome 22, or with the TAF15 gene on chromosome 17, or with the TCF3 (E2A) gene on chromosome 19, have been observed in acute leukemia.[3] | https://www.wikidoc.org/index.php/ZNF384 | |
d1ff111bd7c4d85bf9b7de4c64c94ffb8862cb7d | wikidoc | ZNF423 | ZNF423
Zinc finger protein 423 is a protein that in humans is encoded by the ZNF423 gene.
The protein encoded by this gene is a nuclear protein that belongs to the family of Kruppel-like C2H2 zinc finger proteins. It functions as a DNA-binding transcription factor by using distinct zinc fingers in different signaling pathways. Thus, it is thought that this gene may have multiple roles in signal transduction during development. Mice lacking the homologous gene Zfp423 have defects in midline brain development, especially in the cerebellum, as well as defects in olfactory development, and adipogenesis. Patients with mutations in ZNF423 have been reported in Joubert Syndrome and nephronophthisis.
# Interactions
ZNF423 has been shown to interact with EBF1, PARP1, Notch intracellular domain, retinoic acid receptor, and CEP290. | ZNF423
Zinc finger protein 423 is a protein that in humans is encoded by the ZNF423 gene.[1][2][3]
The protein encoded by this gene is a nuclear protein that belongs to the family of Kruppel-like C2H2 zinc finger proteins. It functions as a DNA-binding transcription factor by using distinct zinc fingers in different signaling pathways. Thus, it is thought that this gene may have multiple roles in signal transduction during development.[3] Mice lacking the homologous gene Zfp423 have defects in midline brain development, especially in the cerebellum,[4][5][6] as well as defects in olfactory development,[7] and adipogenesis.[8][9] Patients with mutations in ZNF423 have been reported in Joubert Syndrome and nephronophthisis.[10]
# Interactions
ZNF423 has been shown to interact with EBF1,[11] PARP1,[12] Notch intracellular domain,[13] retinoic acid receptor,[14] and CEP290.[10] | https://www.wikidoc.org/index.php/ZNF423 | |
c42ad7594769e80bf93bb0cf6ebb328dfbf9dbe6 | wikidoc | ZNF469 | ZNF469
Zinc finger protein 469 is a protein that in humans is encoded by the ZNF469 gene.
# Function
This gene encodes a zinc-finger protein. Low-percent homology to certain collagens suggests that it may function as a transcription factor or extra-nuclear regulator factor for the synthesis or organization of collagen fibers. Mutations in this gene cause brittle cornea syndrome.
# Clinical significance
Mutations in ZNF469 are associated to keratoconus . | ZNF469
Zinc finger protein 469 is a protein that in humans is encoded by the ZNF469 gene.[1]
# Function
This gene encodes a zinc-finger protein. Low-percent homology to certain collagens suggests that it may function as a transcription factor or extra-nuclear regulator factor for the synthesis or organization of collagen fibers. Mutations in this gene cause brittle cornea syndrome.[1]
# Clinical significance
Mutations in ZNF469 are associated to keratoconus .[2] | https://www.wikidoc.org/index.php/ZNF469 | |
32251d62fb55a4694b13a2656e1782e8cbb0b57e | wikidoc | ZNF703 | ZNF703
ZNF703 is a gene which has been linked with the development of breast cancers. ZNF703 is contained within the NET/N1z family responsible for regulation of transcription essential for developmental growth especially in the hindbrain. Normal functions performed by ZNF703 include adhesion, movement and proliferation of cells. ZNF703 directly accumulates histone deacetylases at gene promoter regions but does not bind to functional DNA.
Following research by scientists at Cancer Research UK, it was the first oncogene discovery in the past six years.
ZNF703 is a part of 8p12 telomeric amplicon that is associated with Luminal B breast cancer. Recently, ZNF703 is identified as the driver of 8p12 locus amplification.
Patients diagnosed with luminal B cancer caused by ZNF703 typically have lower recovery and survival rates than other cancer types.
Drug resistance of ZNF703 has been displayed when patients are treated using anti-cancer drug Tamoxifen.
# Discovery
Researchers discovered the carcinogenic nature of ZNF703 in 2011 while conducting research on the classification and resistance of various oncogenes. Researchers attempted to discern factors associated with various cancer types through observation of the oncogenic mechanism on a molecular scale. The luminal B cancer pathway exhibited an amplification of 5 different genomic areas including the chromosome region 8p12. Amplification of region 8p12 occurred through transcriptional regulation of ZNF703.
# Location
ZNF703 is located on human chromosome 8 at the short arm region commonly named chromosome region 8p12. Tumors generated by ZNF703 have shown loss in size beginning at the telomere and ending at 8p12 while the 8p12-11 region has increased size. A fluctuation between increase and decrease is present along the 8p12-8p21 boundary region of the chromosome. A pattern has been found that involves three similar regions of disrupted growth and four regions of enhanced growth starting from the telomere and ending at the centromere.
# Role in cancer
The ZNF703 gene generally plays an active role in luminal B tumor cells contained in mammary ducts. Typically, ZNF703 expression is greater when the tumors are estrogen receptor positive as opposed to estrogen receptor negative. ZNF703 is co-expressed in a nuclear complex containing genes DCAF7, NCRO2 and PHB2. ZNF703 generates a nuclear protein responsible for oestrogen receptor associated protein repression. Gene expression of stem cells are triggered when the ZNF703 gene becomes overexpressed in the complex. As a result, both regular cells and cancer stem cell abundance increases rapidly. ZNF703 overexpression also causes primary and secondary tumorsphere development alongside amplified production of CD49F- positive cells associated with colon cancer.
ZNF703 also experiences target regulation of cancer cells through the transcription of RNA SPRY4-It1. RNA SPRY4-IT1 is a non-coding gene responsible for preventing apoptosis and generating large tumors.
Researchers recently established a link between the trigger gene ZNF703 and Akt/mTOR pathway activation involved in the cellular cycle resulting in lung tumor formation.
# Prognosis
The lifespan of individuals with colorectal cancer and luminal cancer have different prognosis depending on the amount of expression of the ZNF703 gene. Low amounts of transcription of ZNF703 usually leads to a healthier prognosis than individuals experiencing higher levels of transcription of the oncogene. ZNF703 is a target for therapeutic medicines since survival rates increase as transcription rates decrease.
# Resistance to drugs
The drug Tamoxifen is a commonly administered drug used to treat luminal cancers in patients. Half of patients treated with Tamoxifen are resistant to the drug. Overexpression of ZNF703 has been linked to Tamoxifen resistance. As transcription of the ZNF703 gene reaches substantial levels, instead of blocking cell proliferation, Tamoxifen is found to increase cancer cell division. Tamoxifen can only be given at low dosages and patients are monitored daily in order to avoid tumor growth. | ZNF703
ZNF703[1] is a gene which has been linked with the development of breast cancers.[2][3][4] ZNF703 is contained within the NET/N1z family responsible for regulation of transcription essential for developmental growth especially in the hindbrain.[5] Normal functions performed by ZNF703 include adhesion, movement and proliferation of cells.[5] ZNF703 directly accumulates histone deacetylases at gene promoter regions but does not bind to functional DNA.[6]
Following research by scientists at Cancer Research UK, it was the first oncogene discovery in the past six years.[3]
ZNF703 is a part of 8p12 telomeric amplicon that is associated with Luminal B breast cancer. Recently, ZNF703 is identified as the driver of 8p12 locus amplification.[7]
Patients diagnosed with luminal B cancer caused by ZNF703 typically have lower recovery and survival rates than other cancer types.[8]
Drug resistance of ZNF703 has been displayed when patients are treated using anti-cancer drug Tamoxifen.[9]
# Discovery
Researchers discovered the carcinogenic nature of ZNF703 in 2011 while conducting research on the classification and resistance of various oncogenes.[5] Researchers attempted to discern factors associated with various cancer types through observation of the oncogenic mechanism on a molecular scale.[5] The luminal B cancer pathway exhibited an amplification of 5 different genomic areas including the chromosome region 8p12.[5] Amplification of region 8p12 occurred through transcriptional regulation of ZNF703.[5]
# Location
ZNF703 is located on human chromosome 8 at the short arm region commonly named chromosome region 8p12.[2] Tumors generated by ZNF703 have shown loss in size beginning at the telomere and ending at 8p12 while the 8p12-11 region has increased size.[10] A fluctuation between increase and decrease is present along the 8p12-8p21 boundary region of the chromosome.[10] A pattern has been found that involves three similar regions of disrupted growth and four regions of enhanced growth starting from the telomere and ending at the centromere.[10]
# Role in cancer
The ZNF703 gene generally plays an active role in luminal B tumor cells contained in mammary ducts.[2] Typically, ZNF703 expression is greater when the tumors are estrogen receptor positive as opposed to estrogen receptor negative.[2] ZNF703 is co-expressed in a nuclear complex containing genes DCAF7, NCRO2 and PHB2.[2] ZNF703 generates a nuclear protein responsible for oestrogen receptor associated protein repression.[2] Gene expression of stem cells are triggered when the ZNF703 gene becomes overexpressed in the complex.[2] As a result, both regular cells and cancer stem cell abundance increases rapidly.[2] ZNF703 overexpression also causes primary and secondary tumorsphere development alongside amplified production of CD49F- positive cells associated with colon cancer.[2]
ZNF703 also experiences target regulation of cancer cells through the transcription of RNA SPRY4-It1.[11] RNA SPRY4-IT1 is a non-coding gene responsible for preventing apoptosis and generating large tumors.[11]
Researchers recently established a link between the trigger gene ZNF703 and Akt/mTOR pathway activation involved in the cellular cycle resulting in lung tumor formation.[12]
# Prognosis
The lifespan of individuals with colorectal cancer and luminal cancer have different prognosis depending on the amount of expression of the ZNF703 gene.[8] Low amounts of transcription of ZNF703 usually leads to a healthier prognosis than individuals experiencing higher levels of transcription of the oncogene.[8] ZNF703 is a target for therapeutic medicines since survival rates increase as transcription rates decrease.[8]
# Resistance to drugs
The drug Tamoxifen is a commonly administered drug used to treat luminal cancers in patients.[9] Half of patients treated with Tamoxifen are resistant to the drug.[9] Overexpression of ZNF703 has been linked to Tamoxifen resistance.[9] As transcription of the ZNF703 gene reaches substantial levels, instead of blocking cell proliferation, Tamoxifen is found to increase cancer cell division.[9] Tamoxifen can only be given at low dosages and patients are monitored daily in order to avoid tumor growth.[9] | https://www.wikidoc.org/index.php/ZNF703 | |
11cc4cccaaa7e22ed8381663eedef5eac690d4ef | wikidoc | Zif268 | Zif268
Zif268 is a mammalian transcription factor that is now officially known as Egr1 (Early Growth Response Protein 1). It was also named Krox-24, NGFI-A, TIS8, and ZENK. It was originally discovered in mouse.
The protein encoded by this gene belongs to the EGR family of C2H2-type zinc-finger proteins. It is a nuclear protein and functions as a transcriptional regulator. The products of target genes it activates are required for differentitation and mitogenesis. Studies suggest this is a cancer suppresor gene.
# Structure
The DNA binding domain of Zif268 consists of three zinc finger domains of the Cys2His2 type.
The amino acid structure of the Zif268 zinc finger domain is given in this table, using the single letter amino acid code. The fingers 1 to 3 are indicated by f1 - f3. The numbers are in reference to the residues (amino acids) of alpha helix (there is no '0'). The residues marked 'x' are not part of the zinc fingers, but rather serve to connect them all together.
The crystal structure of DNA bound by the zinc finger domain of Zif268 was solved in 1991, which greatly aided early research in zinc finger DNA-binding domains.
The human Zif268/EGR1 protein contains (in its unprocessed form) 543 amino acids with a molecular weight of 57.5 kDa, and the gene is located on the chromosome 5.
# Function
Zif268 binds the DNA sequence 5'-GCGGGCG-3.
It has a distinct pattern of expression in the brain, and its induction has been shown to be assiociated with neuronal activity. Several studies suggest it has a role in neuronal plasticity.
Zif268 has also been found to regulate the expression of synaptobrevin II (a protein important for synaptic exocytosis). | Zif268
Zif268 is a mammalian transcription factor that is now officially known as Egr1 (Early Growth Response Protein 1). It was also named Krox-24, NGFI-A, TIS8, and ZENK. It was originally discovered in mouse.
The protein encoded by this gene belongs to the EGR family of C2H2-type zinc-finger proteins. It is a nuclear protein and functions as a transcriptional regulator. The products of target genes it activates are required for differentitation and mitogenesis. Studies suggest this is a cancer suppresor gene.[1]
# Structure
The DNA binding domain of Zif268 consists of three zinc finger domains of the Cys2His2 type.
The amino acid structure of the Zif268 zinc finger domain is given in this table, using the single letter amino acid code. The fingers 1 to 3 are indicated by f1 - f3. The numbers are in reference to the residues (amino acids) of alpha helix (there is no '0'). The residues marked 'x' are not part of the zinc fingers, but rather serve to connect them all together.
The crystal structure of DNA bound by the zinc finger domain of Zif268 was solved in 1991, which greatly aided early research in zinc finger DNA-binding domains.[2]
The human Zif268/EGR1 protein contains (in its unprocessed form) 543 amino acids with a molecular weight of 57.5 kDa, and the gene is located on the chromosome 5.
# Function
Zif268 binds the DNA sequence 5'-GC[G/T]GGGCG-3.[3][4]
It has a distinct pattern of expression in the brain, and its induction has been shown to be assiociated with neuronal activity. Several studies suggest it has a role in neuronal plasticity.[5]
Zif268 has also been found to regulate the expression of synaptobrevin II (a protein important for synaptic exocytosis).[6] | https://www.wikidoc.org/index.php/Zif268 | |
f49c7c8cb0a704e10f88038659e3e4aae3727062 | wikidoc | 9-1-1 | 9-1-1 or 911 (usually pronounced "nine-one-one") is the emergency telephone number for the North American Numbering Plan (NANP). It is one of eight N11 codes. The use of this number is reserved for true emergency circumstances only. Use of 9-1-1 under non-emergency circumstances may result in a criminal charge.
# Development of 9-1-1
Before the dial telephone came into widespread usage, a caller simply picked up the telephone receiver and waited for the operator to answer "number please?" The caller then said "connect me to the police," "I want to report a fire," or "I need an ambulance/doctor." It was usually not necessary to ask for any of these services by number, even in a large city. Furthermore, the operator instantly knew the calling party's number even if he couldn't stay on the line by simply looking at the number above the line jack of the calling party.
In small towns, telephone operators frequently went the extra mile by making sure they knew the locations of local doctors, vets, law enforcement personnel, and even private citizens who were willing or able to help in an emergency. Frequently, the operator also activated the town's fire alarm.
When cities and towns began to convert to dial or, "automatic" telephone service, many people were concerned about the loss of the personalized service that had been provided by local operators. This problem was partially solved by telling people to dial "0" for the local assistance operator if they did not know the Fire or Police Department's full number.
Generations of school children were taught to "dial 0 in case of emergency," and this situation remained in place in some areas into the early 1980s. Nowadays children are taught to call 911.
The push for the development of a nationwide emergency telephone number came in 1957 when the National Association of Fire Chiefs recommended a single number to be used for reporting fires. In 1967, the President's Commission on Law Enforcement and Administration of Justice recommended the creation of a single number that can be used nationwide for reporting emergencies. The burden then fell on the Federal Communications Commission, which then met with AT&T in November 1967 in order to come up with a solution.
In 1968, a solution was agreed upon. AT&T had chosen the number 911, which met the requirements that it be brief, easy to remember, dialed easily, and that it worked well with the phone systems in place at the time. How the number 911 itself was chosen is not well known and is subject to much speculation. However, many assert that the number 911 was chosen to be similar to the numbers 2-1-1 (long distance), 4-1-1 (information, later called "directory assistance"), and 6-1-1 (repair service), which had already been in use by AT&T since 1966. Also, it was necessary to ensure that the 9-1-1 number was not dialed accidentally, so 9-1-1 made sense because the numbers "9" and "1" were on opposite ends of a phone's rotary dial.
Furthermore, the North American Numbering Plan in use at the time established rules for which numbers can be used for area codes and exchanges. At the time, the middle digit of an area code had to be either a 0 or 1, and the first two digits of an exchange could not be a 1. At the telephone switching station, the second dialed digit was used to determine if the number was long distance or local. If the number had a 0 or 1 as the second digit, it was long distance, and it was a local call if it was any other number. Thus, since the number 911 was detected by the switching equipment as a special number, it could be routed appropriately. Also, since 911 was a unique number, never having been used as an area code or service code (although at one point GTE used test numbers such as 11911), it fit into the phone system easily.
AT&T announced the selection of 9-1-1 as their choice of the three-digit emergency number at a press conference in the Washington (DC) office of Indiana Rep. J. Edward Roush, who had championed Congressional support of a single emergency number.
In Alabama, Bob Gallagher, president of the independent Alabama Telephone Co. read an article in the Wall Street Journal on Jan. 15, 1968, which reported the AT&T 911 announcement. Gallagher’s competitive spirit motivated him to beat AT&T to the punch by being the first to implement the 911 service, somewhere within the Alabama Telephone Co. territory. He contacted Robert Fitzgerald, who was Inside State Plant Manager for ATC, who in turn recommended Haleyville, Alabama as the prime site. Gallagher later issued a press release announcing that the 911 service would begin in Haleyville on Feb.16, 1968. Fitzgerald designed the circuitry, and with the assistance of technicians Jimmy White, Glenn Johnston, Al Bush and Pete Gosa, quickly completed the central office work and installation.
Just 35 days after AT&T's announcement, on February 16, 1968, the first-ever 9-1-1 call was placed by Alabama Speaker of the House Rankin Fite from Haleyville City Hall to U.S. Rep. Tom Bevill (Dem.) at the city's police station. Bevill reportedly answered the phone with "Hello." Attending with Fite was Haleyville mayor James Whitt. At the police station with Bevill was Gallagher and Alabama Public Service Commission director Eugene "Bull" Connor (formerly the Birmingham police chief involved in federal desegregation). Fitzgerald was at the ATC central office serving Haleyville, and actually observed the call pass through the switching gear, as the mechanical equipment clunked out "9-1-1." The phone used to answer the first 911 call, a bright red model, is now in a museum in Haleyville, while a duplicate phone is still in use at the police station. Some accounts of the event claim that, "Later, the two (Bevill and Fite) said they exchanged greetings, hung up and 'had coffee and doughnuts.'"
In 1973, the White House urged nationwide adoption of 911. In 1999, President Bill Clinton signed the bill that designated 911 as the nationwide emergency number. Even though 9-1-1 was introduced in 1968, the network still does not completely cover some rural areas of the United States and Canada.
# 9-1-1 Emergency Telephone Number Day
9-1-1 Emergency Telephone Number Day was proclaimed, by The proclamation was made to promote the North American universal emergency telephone number 9-1-1.
Until 2001, September 11 was celebrated by many United States communities as "9-1-1 emergency number day" or simply "911 day". The promotional effort was often led by firefighters and the police. After the September 11, 2001 attacks, the reminders of 9-1-1 were dropped in favor of remembrance of the victims of the attacks.
Another way of recognizing the efforts of the people involved in 9-1-1, and Public Safety Communications in-general, is National Public Safety Telecommunications Week (or as it is commonly called, Dispatchers' Week), which occurs during the second week in April.
# Funding of 9-1-1
9-1-1 and enhanced 9-1-1 are typically funded pursuant to state laws that impose monthly fees on local and wireless telephone customers. Depending on the state, counties and cities may also levy a fee, which may be in addition to, or in lieu of, the state fee. The fees are collected by local exchange and wireless carriers through monthly surcharges on customer telephone bills. The collected fees are remitted to 911 administrative bodies, which may be a statewide 911 board, the state public utility commission, a state revenue department, or local 911 agencies. These agencies disburse the funds to the Public Safety Answering Points for 911 purposes as specified in the various statutes. Telephone companies, including wireless carriers, may be entitled to apply for and receive reimbursements for costs of compliance with federal and state laws requiring that their networks be compatible with 9-1-1 and enhanced 9-1-1.
The amount of the fees vary widely by locality. Fees may range from around $.25 per month to $3.00 per month per line. The average wireless 9-1-1 fee in the United States is around $.72, which is based on the fees for each state as published by the National Emergency Number Association (NENA). Since the monthly fees do not vary by the customer's usage of the network, the fees are considered, in tax terms, as highly "regressive", i.e., the fees disproportionately burden low-volume users of the public switched network (PSN) as compared with high-volume users. Some states cap the number of lines subject to the fee for large multi-line businesses, thereby shifting more of the fee burden to low-volume single-line residential customers or wireless customers.
Congress in 2004 authorized $250,000,000 USD in annual funding for the 9-1-1 program, but actual federal appropriations to state and local 9-1-1 agencies are yet to occur (as of June 2006).
# Locating callers automatically
In over 93% of locations in the United States and Canada, dialing "911" from any telephone will link the caller to an emergency dispatch center—called a PSAP, or Public Safety Answering Point, by the telecom industry—which can send emergency responders to the caller's location in an emergency. In some areas enhanced 911 is available, which automatically gives dispatch the caller's location, if available. Users should never be fooled into thinking that the information the 911 operator has on the caller's location or phone number is accurate. It is of paramount importance for the caller to verify their location and phone number in order to ensure help gets to the right location.
Dialing 9-1-1 from a mobile phone (Cellular/PCS) in the United States originally reached the state police or highway patrol, instead of the local public safety answering point (PSAP). The caller had to describe his/her exact location so that the agency could transfer the call to the correct local emergency services. This happens because the exact location of the cellular phone isn't normally transmitted with the voice call.
In 2000 the FCC issued an order requiring wireless carriers to determine and transmit the location of callers who dial 9-1-1. They set up a phased program: Phase I transmitted the location of the receiving antenna for 9-1-1 calls, while Phase II transmitted the location of the calling telephone. The order set up certain accuracy requirements and other technical details, and milestones for completing the implementation of wireless location services. Subsequent to the FCC's order, many wireless carriers requested waivers of the milestones, and the FCC granted many of them. As of mid-2005, the process of Phase II implementation is generally underway, but limited by the complexity of coordination required between wireless carriers, PSAPs, local telephone companies and other affected government agencies, and the limited funding available to local agencies for the conversion of PSAP equipment to display the location data (usually on computerized maps).
These FCC rules require new mobile phones to provide their latitude and longitude to emergency operators in the event of a 911 call. Carriers may choose whether to implement this via GPS chips in each phone, or via triangulation between cell towers. In addition, the rules require carriers to connect 911 calls from any mobile phone, regardless of whether that phone is currently active. Due to limitations in technology (of the mobile phone, cell phone towers, and PSAP equipment), a mobile caller's geographical information may not always be available to the local PSAP. Although there are other ways, in addition to those previously stated, in which to obtain the geographical location of the caller, the caller should try to be aware of the location of the incident for which they are calling.
In the U.S., Federal Communications Commission (FCC) rules require every telephone that can physically access the network to be able to dial 911, regardless of any reason that normal service may have been disconnected (including non-payment). On wired (land line) phones, this usually is accomplished by a "soft" dial tone, which sounds normal, but will only allow emergency calls. Often, an unused and unpublished phone number will be issued to the line so that it will work properly.
If 911 is dialed from a commercial VoIP service, depending on how the provider handles such calls, the call may not go anywhere at all, or it may go to a non-emergency number at the public safety answering point associated with the billing or service address of the caller. Because a VoIP adapter can be plugged into any broadband internet connection, the caller could actually be hundreds or even thousands of miles away from home, yet if the call goes to an answering point at all, it would be the one associated with the caller's address and not the actual location. It may never be possible to accurately pinpoint the exact location of a VoIP user (even if a GPS receiver is installed in the VoIP adapter, it will likely be indoors, and may not be able to get a signal), so users should be aware of this limitation and make other arrangements for summoning assistance in an emergency.
In March 2005, commercial Internet telephony provider Vonage was sued by the Texas attorney general, who alleged that their website and other sales and service documentation did not make clear enough that Vonage's provision of 911 service was not done in the traditional manner.
In May 2005, the FCC issued an Order requiring VoIP providers to offer 9-1-1 service to all their subscribers within 120 days of the Order being published. The order set off anxiety among many VoIP providers, who felt it would be too expensive and require them to adopt solutions that wouldn't support future VoIP products.
# Problems
There are some issues with the assignment of the number 9-1-1.
## Nine-One-One or Nine-Eleven?
When the 9-1-1 system was originally introduced, it was advertised as the "nine-eleven" service. This was changed when some panicked individuals tried to find the "eleven" key on their telephones (seemingly amusing, but it is important to remember that in emergencies people can easily become extremely confused and irrational). Therefore, all references to the telephone number 9-1-1 are now always made as nine-one-one — never as "nine-eleven" per standards outlined by the National Emergency Number Association (NENA). Some newspapers and other media require that references to the phone number be formatted as 9-1-1, also a suggested standard by NENA. Since September 11, 2001, "nine-eleven" is used almost exclusively to refer to the September 11, 2001 attacks, but is also used for the Porsche 911 sports car. In Spanish, 9-1-1 is known as "nueve once", which means "nine-eleven".
## Dialing patterns
In particular, it can cause some dialing-pattern problems in hotels and businesses. Some hotels, for example, have been known to require dialing "91+" to make an outside call. This leads to calls that look like 91+1+301+555+2368. Since this is a valid number, which starts with 911, and is not a call to an emergency service, a timeout becomes necessary on calls dialed literally as 911. Such prefixes are strongly discouraged by telephone companies. This is also part of the reason why no area codes start with a "1": the slightly less troublesome "outside line" prefix of "9+" would then cause the same problem: "9+114+555+2368", for example. Another possible problem is that the international phone code for India is "91", and sometimes calls meant for India end up at the local emergency dispatch office if the caller did not dial the international call prefix 011.
Some businesses also require just a simple "9" to dial out of their network. This was parodied in an episode of Andy Richter Controls the Universe, where a co-worker laments that her dead colleague dialed 9-1-1 instead of 9-9-1-1. This "less troublesome" prefix can still cause problems, if a caller dials "9+1+XXX+XXX+XXXX" and the 1 button on the tone dial "skips" and sends 2 "1" digits -- again, the number will then start with "9-1-1", and if the PBX "cuts through" 9-1-1 to emergency services (as many do, and many others recommend), this will provide another opportunity for mistaken emergency calling.
## Emergencies across jurisdictions
When a caller dials 9-1-1, the call is routed to the local public safety answering point. However, if the caller is attempting to notify authorities in another jurisdiction of an emergency in the area, the process can be complicated. For example, a caller in Dallas, Texas aware of an emergency occurring in Little Rock, Arkansas would have access to 9-1-1 only in Dallas, whose dispatchers may or may not know how to contact the proper authorities in Little Rock. The publicly posted phone numbers for most police departments in the U.S. are non-emergency numbers that often specifically instruct callers to dial 9-1-1 in case of emergency, which does not resolve the issue for callers outside of the jurisdiction. In the age of both commercial and personal high speed Internet communications, this issue is becoming an increasing problem.
The FBI, however, has combated this problem by listing an on-line directory of all law enforcement agencies in the United States. This directory is available only to agencies with access to the NCIC/NLETS database, but allows dispatchers to quickly locate after-hour numbers for cross-jurisdictional agencies. The query has been named ORION. Not all local law enforcement agencies have access to this directory, however.
## Media-caused confusion
For many years after the popular TV show Hawaii Five-O finished its run, GTE Hawaiian Tel included a warning in its phone books that in an emergency, people should dial 9-1-1 and not Hawaii Five-O (as some confused tourists had done). The AAA auto club provided a similar warning in its Hawaii Tourbook travelers guidebook.
# International emergency numbers and numbers in other countries
There is no worldwide common emergency number.
Outside of the U.S. and Canada, 911 doesn't work in most countries. Other common emergency numbers are 112 and 999. 911 is used so pervasively in U.S. and Canadian media programming and safety education material, in the case the materials are exported to countries which emergency number is not 911, the countries sometimes had difficulty in educating children not to dial 911 for help.
An example of this is Uruguay, where the emergency number was traditionally 999, but was changed to 911 in 2001 after many cases where people dialed 911 instead of 999 during an emergency. This was due to the popularity in the country of US television programs and movies which routinely mention 911 as the emergency number to dial.
In 1991, the European Union established 1-1-2 as the universal emergency number for all its member states. In most E.U. countries, 1-1-2 is already implemented and can be called toll-free from any telephone or any cellphone. The GSM mobile phone standard designates 1-1-2 as an emergency number, so it will work on such systems even in North America. In the UK and Republic of Ireland, the number is 9-9-9 with 1-1-2 working in parallel. In the UK, the dashes are very rarely used, so the number is almost always written simply 999.
# 9-1-1 in popular culture
- The number's close association with emergencies has led to 911 being used as shorthand for emergency in text messages sent to pagers and mobile phones—however, this is often used to tag situations which do not have the life-safety implications that an actual call to 911 implies.
- The hip hop group Public Enemy released a song that was scathingly critical of the 9-1-1 service entitled “911 Is A Joke” on their 1990 album Fear of a Black Planet. The song highlighted the poor performance of the 9-1-1 service in predominantly black neighborhoods.
- The Cyndi Lauper album True Colors contains a track entitled “911.”
- In an episode of The Simpsons, Homer picks up the phone and says, "Operator, give me the number for 9-1-1!" (As one will see, this is not an isolated incident.) He also receives the "true" emergency phone number of 9-1-2 when he joins the Stonecutters.
- In another episode of The Simpsons, police chief Clancy Wiggum apparently receives a 9-1-1 call at his home during the town lottery, to which he responds, "No, you got the wrong number. This is nine-one....two."
- From 1989 to 1996 CBS aired Rescue 911, a television show which featured host William Shatner and dramatic recreations of actual emergencies and the corresponding response of 9-1-1.
- In the “Crazy For You” episode of Home Improvement, Tim Allen's Tim Taylor calls the operator and says "Operator - what's the number for 911?" He then tells the operator to "slow down" as he writes it down.
- In the movie The Santa Clause, also with Tim Allen; upon hearing the noise on his roof, Allen's Scott Calvin asks his son if he knows how to dial 9-1-1 to which the son replies, "yeah, 9-1-1."
- On the 1992 "Earthquake!" episode of Saved By The Bell, a character is told to call 911. The character promptly asks, "What's the number?" A similar scene also occurred in Ed,_Edd_n_Eddy.
- In the 1994 film adaptation of Little Rascals, two kids in the gang consider calling the fire department to put out a fire, but decide otherwise when they realize neither of them knows the number for 911. In the scene, the fire department is actually across the street from the pay phone they were using. One of the kids asks someone "What is the number for 911?"
- In the Disney animated movie Hercules, Hercules rescues two children from a cave-in in a gorge (which was actually a staged calamity to lure Hercules into danger), and one of the children can be heard saying; "Someone call IX I I", which are the Roman numerals for 9-1-1.
- The American TV show Reno 9-1-1! Features Lt. Jim Dangle and the escapades of the Reno Sheriff's department on the Comedy Central Channel. | 9-1-1
Template:Otheruses2
Template:Cleanup
9-1-1 or 911 (usually pronounced "nine-one-one") is the emergency telephone number for the North American Numbering Plan (NANP). It is one of eight N11 codes. The use of this number is reserved for true emergency circumstances only. Use of 9-1-1 under non-emergency circumstances may result in a criminal charge.
# Development of 9-1-1
Before the dial telephone came into widespread usage, a caller simply picked up the telephone receiver and waited for the operator to answer "number please?" The caller then said "connect me to the police," "I want to report a fire," or "I need an ambulance/doctor." It was usually not necessary to ask for any of these services by number, even in a large city. Furthermore, the operator instantly knew the calling party's number even if he couldn't stay on the line by simply looking at the number above the line jack of the calling party.
In small towns, telephone operators frequently went the extra mile by making sure they knew the locations of local doctors, vets, law enforcement personnel, and even private citizens who were willing or able to help in an emergency. Frequently, the operator also activated the town's fire alarm.
When cities and towns began to convert to dial or, "automatic" telephone service, many people were concerned about the loss of the personalized service that had been provided by local operators. This problem was partially solved by telling people to dial "0" for the local assistance operator if they did not know the Fire or Police Department's full number.
Generations of school children were taught to "dial 0 in case of emergency," and this situation remained in place in some areas into the early 1980s. Nowadays children are taught to call 911.
The push for the development of a nationwide emergency telephone number came in 1957 when the National Association of Fire Chiefs recommended a single number to be used for reporting fires. In 1967, the President's Commission on Law Enforcement and Administration of Justice recommended the creation of a single number that can be used nationwide for reporting emergencies. The burden then fell on the Federal Communications Commission, which then met with AT&T in November 1967 in order to come up with a solution.
In 1968, a solution was agreed upon. AT&T had chosen the number 911, which met the requirements that it be brief, easy to remember, dialed easily, and that it worked well with the phone systems in place at the time. How the number 911 itself was chosen is not well known and is subject to much speculation. However, many assert that the number 911 was chosen to be similar to the numbers 2-1-1 (long distance), 4-1-1 (information, later called "directory assistance"), and 6-1-1 (repair service), which had already been in use by AT&T since 1966. Also, it was necessary to ensure that the 9-1-1 number was not dialed accidentally, so 9-1-1 made sense because the numbers "9" and "1" were on opposite ends of a phone's rotary dial.
Furthermore, the North American Numbering Plan in use at the time established rules for which numbers can be used for area codes and exchanges. At the time, the middle digit of an area code had to be either a 0 or 1, and the first two digits of an exchange could not be a 1. At the telephone switching station, the second dialed digit was used to determine if the number was long distance or local. If the number had a 0 or 1 as the second digit, it was long distance, and it was a local call if it was any other number. Thus, since the number 911 was detected by the switching equipment as a special number, it could be routed appropriately. Also, since 911 was a unique number, never having been used as an area code or service code (although at one point GTE used test numbers such as 11911), it fit into the phone system easily.
AT&T announced the selection of 9-1-1 as their choice of the three-digit emergency number at a press conference in the Washington (DC) office of Indiana Rep. J. Edward Roush, who had championed Congressional support of a single emergency number.
In Alabama, Bob Gallagher, president of the independent Alabama Telephone Co. read an article in the Wall Street Journal on Jan. 15, 1968, which reported the AT&T 911 announcement. Gallagher’s competitive spirit motivated him to beat AT&T to the punch by being the first to implement the 911 service, somewhere within the Alabama Telephone Co. territory. He contacted Robert Fitzgerald, who was Inside State Plant Manager for ATC, who in turn recommended Haleyville, Alabama as the prime site. Gallagher later issued a press release announcing that the 911 service would begin in Haleyville on Feb.16, 1968. Fitzgerald designed the circuitry, and with the assistance of technicians Jimmy White, Glenn Johnston, Al Bush and Pete Gosa, quickly completed the central office work and installation.[1]
Just 35 days after AT&T's announcement, on February 16, 1968, the first-ever 9-1-1 call was placed by Alabama Speaker of the House Rankin Fite from Haleyville City Hall to U.S. Rep. Tom Bevill (Dem.) at the city's police station. Bevill reportedly answered the phone with "Hello." Attending with Fite was Haleyville mayor James Whitt. At the police station with Bevill was Gallagher and Alabama Public Service Commission director Eugene "Bull" Connor (formerly the Birmingham police chief involved in federal desegregation). Fitzgerald was at the ATC central office serving Haleyville, and actually observed the call pass through the switching gear, as the mechanical equipment clunked out "9-1-1." The phone used to answer the first 911 call, a bright red model, is now in a museum in Haleyville, while a duplicate phone is still in use at the police station. Some accounts of the event claim that, "Later, the two (Bevill and Fite) said they exchanged greetings, hung up and 'had coffee and doughnuts.'"
In 1973, the White House urged nationwide adoption of 911. In 1999, President Bill Clinton signed the bill that designated 911 as the nationwide emergency number. Even though 9-1-1 was introduced in 1968, the network still does not completely cover some rural areas of the United States and Canada.
# 9-1-1 Emergency Telephone Number Day
9-1-1 Emergency Telephone Number Day was proclaimed, by[President Reagan in 1987, to occur on September 11th of that year.[2] The proclamation was made to promote the North American universal emergency telephone number 9-1-1.
Until 2001, September 11 was celebrated by many United States communities as "9-1-1 emergency number day" or simply "911 day". The promotional effort was often led by firefighters and the police. After the September 11, 2001 attacks, the reminders of 9-1-1 were dropped in favor of remembrance of the victims of the attacks.
Another way of recognizing the efforts of the people involved in 9-1-1, and Public Safety Communications in-general, is National Public Safety Telecommunications Week (or as it is commonly called, Dispatchers' Week), which occurs during the second week in April.
# Funding of 9-1-1
9-1-1 and enhanced 9-1-1 are typically funded pursuant to state laws that impose monthly fees on local and wireless telephone customers. Depending on the state, counties and cities may also levy a fee, which may be in addition to, or in lieu of, the state fee. The fees are collected by local exchange and wireless carriers through monthly surcharges on customer telephone bills. The collected fees are remitted to 911 administrative bodies, which may be a statewide 911 board, the state public utility commission, a state revenue department, or local 911 agencies. These agencies disburse the funds to the Public Safety Answering Points for 911 purposes as specified in the various statutes. Telephone companies, including wireless carriers, may be entitled to apply for and receive reimbursements for costs of compliance with federal and state laws requiring that their networks be compatible with 9-1-1 and enhanced 9-1-1.
The amount of the fees vary widely by locality. Fees may range from around $.25 per month to $3.00 per month per line. The average wireless 9-1-1 fee in the United States is around $.72, which is based on the fees for each state as published by the National Emergency Number Association (NENA). Since the monthly fees do not vary by the customer's usage of the network, the fees are considered, in tax terms, as highly "regressive", i.e., the fees disproportionately burden low-volume users of the public switched network (PSN) as compared with high-volume users. Some states cap the number of lines subject to the fee for large multi-line businesses, thereby shifting more of the fee burden to low-volume single-line residential customers or wireless customers.
Congress in 2004 authorized $250,000,000 USD in annual funding for the 9-1-1 program, but actual federal appropriations to state and local 9-1-1 agencies are yet to occur (as of June 2006).
# Locating callers automatically
In over 93% of locations in the United States and Canada, dialing "911" from any telephone will link the caller to an emergency dispatch center—called a PSAP, or Public Safety Answering Point, by the telecom industry—which can send emergency responders to the caller's location in an emergency. In some areas enhanced 911 is available, which automatically gives dispatch the caller's location, if available. Users should never be fooled into thinking that the information the 911 operator has on the caller's location or phone number is accurate. It is of paramount importance for the caller to verify their location and phone number in order to ensure help gets to the right location.
Dialing 9-1-1 from a mobile phone (Cellular/PCS) in the United States originally reached the state police or highway patrol, instead of the local public safety answering point (PSAP). The caller had to describe his/her exact location so that the agency could transfer the call to the correct local emergency services. This happens because the exact location of the cellular phone isn't normally transmitted with the voice call.
In 2000 the FCC issued an order requiring wireless carriers to determine and transmit the location of callers who dial 9-1-1. They set up a phased program: Phase I transmitted the location of the receiving antenna for 9-1-1 calls, while Phase II transmitted the location of the calling telephone. The order set up certain accuracy requirements and other technical details, and milestones for completing the implementation of wireless location services. Subsequent to the FCC's order, many wireless carriers requested waivers of the milestones, and the FCC granted many of them. As of mid-2005, the process of Phase II implementation is generally underway, but limited by the complexity of coordination required between wireless carriers, PSAPs, local telephone companies and other affected government agencies, and the limited funding available to local agencies for the conversion of PSAP equipment to display the location data (usually on computerized maps).
These FCC rules require new mobile phones to provide their latitude and longitude to emergency operators in the event of a 911 call. Carriers may choose whether to implement this via GPS chips in each phone, or via triangulation between cell towers. In addition, the rules require carriers to connect 911 calls from any mobile phone, regardless of whether that phone is currently active. Due to limitations in technology (of the mobile phone, cell phone towers, and PSAP equipment), a mobile caller's geographical information may not always be available to the local PSAP. Although there are other ways, in addition to those previously stated, in which to obtain the geographical location of the caller, the caller should try to be aware of the location of the incident for which they are calling.
In the U.S., Federal Communications Commission (FCC) rules require every telephone that can physically access the network to be able to dial 911, regardless of any reason that normal service may have been disconnected (including non-payment). On wired (land line) phones, this usually is accomplished by a "soft" dial tone, which sounds normal, but will only allow emergency calls. Often, an unused and unpublished phone number will be issued to the line so that it will work properly.
If 911 is dialed from a commercial VoIP service, depending on how the provider handles such calls, the call may not go anywhere at all, or it may go to a non-emergency number at the public safety answering point associated with the billing or service address of the caller. Because a VoIP adapter can be plugged into any broadband internet connection, the caller could actually be hundreds or even thousands of miles away from home, yet if the call goes to an answering point at all, it would be the one associated with the caller's address and not the actual location. It may never be possible to accurately pinpoint the exact location of a VoIP user (even if a GPS receiver is installed in the VoIP adapter, it will likely be indoors, and may not be able to get a signal), so users should be aware of this limitation and make other arrangements for summoning assistance in an emergency.
In March 2005, commercial Internet telephony provider Vonage was sued by the Texas attorney general, who alleged that their website and other sales and service documentation did not make clear enough that Vonage's provision of 911 service was not done in the traditional manner.
In May 2005, the FCC issued an Order requiring VoIP providers to offer 9-1-1 service to all their subscribers within 120 days of the Order being published. The order set off anxiety among many VoIP providers, who felt it would be too expensive and require them to adopt solutions that wouldn't support future VoIP products.
# Problems
There are some issues with the assignment of the number 9-1-1.
## Nine-One-One or Nine-Eleven?
When the 9-1-1 system was originally introduced, it was advertised as the "nine-eleven" service. This was changed when some panicked individuals tried to find the "eleven" key on their telephones (seemingly amusing, but it is important to remember that in emergencies people can easily become extremely confused and irrational). Therefore, all references to the telephone number 9-1-1 are now always made as nine-one-one — never as "nine-eleven" per standards outlined by the National Emergency Number Association (NENA). Some newspapers and other media require that references to the phone number be formatted as 9-1-1, also a suggested standard by NENA. Since September 11, 2001, "nine-eleven" is used almost exclusively to refer to the September 11, 2001 attacks, but is also used for the Porsche 911 sports car. In Spanish, 9-1-1 is known as "nueve once", which means "nine-eleven".
## Dialing patterns
In particular, it can cause some dialing-pattern problems in hotels and businesses. Some hotels, for example, have been known to require dialing "91+" to make an outside call. This leads to calls that look like 91+1+301+555+2368. Since this is a valid number, which starts with 911, and is not a call to an emergency service, a timeout becomes necessary on calls dialed literally as 911. Such prefixes are strongly discouraged by telephone companies. This is also part of the reason why no area codes start with a "1": the slightly less troublesome "outside line" prefix of "9+" would then cause the same problem: "9+114+555+2368", for example. Another possible problem is that the international phone code for India is "91", and sometimes calls meant for India end up at the local emergency dispatch office if the caller did not dial the international call prefix 011.
Some businesses also require just a simple "9" to dial out of their network. This was parodied in an episode of Andy Richter Controls the Universe, where a co-worker laments that her dead colleague dialed 9-1-1 instead of 9-9-1-1. This "less troublesome" prefix can still cause problems, if a caller dials "9+1+XXX+XXX+XXXX" and the 1 button on the tone dial "skips" and sends 2 "1" digits -- again, the number will then start with "9-1-1", and if the PBX "cuts through" 9-1-1 to emergency services (as many do, and many others recommend), this will provide another opportunity for mistaken emergency calling.
## Emergencies across jurisdictions
When a caller dials 9-1-1, the call is routed to the local public safety answering point. However, if the caller is attempting to notify authorities in another jurisdiction of an emergency in the area, the process can be complicated. For example, a caller in Dallas, Texas aware of an emergency occurring in Little Rock, Arkansas would have access to 9-1-1 only in Dallas, whose dispatchers may or may not know how to contact the proper authorities in Little Rock. The publicly posted phone numbers for most police departments in the U.S. are non-emergency numbers that often specifically instruct callers to dial 9-1-1 in case of emergency, which does not resolve the issue for callers outside of the jurisdiction. In the age of both commercial and personal high speed Internet communications, this issue is becoming an increasing problem.
The FBI, however, has combated this problem by listing an on-line directory of all law enforcement agencies in the United States. This directory is available only to agencies with access to the NCIC/NLETS database, but allows dispatchers to quickly locate after-hour numbers for cross-jurisdictional agencies. The query has been named ORION. Not all local law enforcement agencies have access to this directory, however. [2]
## Media-caused confusion
For many years after the popular TV show Hawaii Five-O finished its run, GTE Hawaiian Tel included a warning in its phone books that in an emergency, people should dial 9-1-1 and not Hawaii Five-O (as some confused tourists had done)[citation needed]. The AAA auto club provided a similar warning in its Hawaii Tourbook travelers guidebook.
# International emergency numbers and numbers in other countries
Template:Seealso
There is no worldwide common emergency number.
Outside of the U.S. and Canada, 911 doesn't work in most countries. Other common emergency numbers are 112 and 999. 911 is used so pervasively in U.S. and Canadian media programming and safety education material, in the case the materials are exported to countries which emergency number is not 911, the countries sometimes had difficulty in educating children not to dial 911 for help.
An example of this is Uruguay, where the emergency number was traditionally 999, but was changed to 911 in 2001 after many cases where people dialed 911 instead of 999 during an emergency. This was due to the popularity in the country of US television programs and movies which routinely mention 911 as the emergency number to dial.[3]
In 1991, the European Union established 1-1-2 as the universal emergency number for all its member states. In most E.U. countries, 1-1-2 is already implemented and can be called toll-free from any telephone or any cellphone. The GSM mobile phone standard designates 1-1-2 as an emergency number, so it will work on such systems even in North America. In the UK and Republic of Ireland, the number is 9-9-9 with 1-1-2 working in parallel. In the UK, the dashes are very rarely used, so the number is almost always written simply 999.
# 9-1-1 in popular culture
- The number's close association with emergencies has led to 911 being used as shorthand for emergency in text messages sent to pagers and mobile phones—however, this is often used to tag situations which do not have the life-safety implications that an actual call to 911 implies.
- The hip hop group Public Enemy released a song that was scathingly critical of the 9-1-1 service entitled “911 Is A Joke” on their 1990 album Fear of a Black Planet. The song highlighted the poor performance of the 9-1-1 service in predominantly black neighborhoods.
- The Cyndi Lauper album True Colors contains a track entitled “911.”
- In an episode of The Simpsons, Homer picks up the phone and says, "Operator, give me the number for 9-1-1!" (As one will see, this is not an isolated incident.) He also receives the "true" emergency phone number of 9-1-2 when he joins the Stonecutters.
- In another episode of The Simpsons, police chief Clancy Wiggum apparently receives a 9-1-1 call at his home during the town lottery, to which he responds, "No, you got the wrong number. This is nine-one....two."
- From 1989 to 1996 CBS aired Rescue 911, a television show which featured host William Shatner and dramatic recreations of actual emergencies and the corresponding response of 9-1-1.
- In the “Crazy For You” episode of Home Improvement, Tim Allen's Tim Taylor calls the operator and says "Operator - what's the number for 911?" He then tells the operator to "slow down" as he writes it down.
- In the movie The Santa Clause, also with Tim Allen; upon hearing the noise on his roof, Allen's Scott Calvin asks his son if he knows how to dial 9-1-1 to which the son replies, "yeah, 9-1-1."
- On the 1992 "Earthquake!" episode of Saved By The Bell, a character is told to call 911. The character promptly asks, "What's the number?" A similar scene also occurred in Ed,_Edd_n_Eddy.
- In the 1994 film adaptation of Little Rascals, two kids in the gang consider calling the fire department to put out a fire, but decide otherwise when they realize neither of them knows the number for 911. In the scene, the fire department is actually across the street from the pay phone they were using. One of the kids asks someone "What is the number for 911?"
- In the Disney animated movie Hercules, Hercules rescues two children from a cave-in in a gorge (which was actually a staged calamity to lure Hercules into danger), and one of the children can be heard saying; "Someone call IX I I", which are the Roman numerals for 9-1-1.
- The American TV show Reno 9-1-1! Features Lt. Jim Dangle and the escapades of the Reno Sheriff's department on the Comedy Central Channel. | https://www.wikidoc.org/index.php/9-1-1 | |
dc2611a5eda58e6af97f7fb421a322175d981df4 | wikidoc | 9-9-9 | 999 is the United Kingdom's and Ireland's emergency telephone number and Poland's medical emergency number. They are all used alongside the EU standard 112.
999 is also the emergency telephone number in some Commonwealth countries including Bangladesh, Botswana, Ghana, Malaysia and Singapore (the rest use a variety of numbers, including 9-1-1). It is also used in the United Arab Emirates, Hong Kong, Macau, Bahrain and Qatar.
# Hong Kong
The 999 was introduced to Hong Kong during British rule and continues to be used following the handover in 1997.
# Malaysia
The 999 emergency services in Malaysia is manned by about 138 telephonists from Telekom Malaysia. On-going upgrading works are taking place to introduce the Computer-Telephony Integration (CTI) for hospital exchanges, digital mapping to track the callers' locations and Computer Assisted Despatching (CAD) for online connectivity among the agencies providing the emergency services in the country. All calls to the number are made free of charge.
# Poland
The 112 emergency number is an all-service number in Poland like in the other EU states, but old numbers that were traditionally designated for emergencies are still in use parallel to 112. Those are:
- 999 for medical emergency
- 998 for fire emergency
- 997 for Police
# United Kingdom
The 999 service was introduced on 30 June 1937 in the London area. 999 was chosen because of the need for the code to be able to be dialled from A/B button public telephones. The telephone dial (GPO Dial No 11) used with these coin-boxes allowed the digit '0' to be dialled without inserting any money, and it was very easy to adapt the dial to dial '9' without inserting money. All other digits from 2 to 8 were in use somewhere in the UK as the initial digits for subscribers' telephone numbers and hence could not easily be used. Had any other digits been used, other digits between that one and the already free '0' would also have been able to be dialled free of charge. No other telephone numbers existed using combinations of the digits '9' and '0' (other than one in Woolwich) therefore there would be no unauthorised 'free' calls. Thus the easy conversion of coin-box dial was the deciding factor and the fact that 999 was not used anywhere, other than for accessing the occasional 'position 9' of an Engineering Test Desk in the telephone exchange. Numbers beginning with 1 were excluded for other technical reasons - for example, 111 could be dialled by accident by wires making contact. Access to the emergency service is provided for the hearing impaired via Textphone and use of the national 'typetalk' relay service. The number is 18000, having previously been 0800 112999.
Since the introduction of mobile phones, the choice of the number 999 has become a particular problem for UK emergency services, as same-digit sequences are most likely dialled by accident due to vibrations and other objects colliding with a keypad. This problem is less of a concern with emergency numbers that use two different digits (e.g., 112, 911).
The pan-European 112 code was introduced in the UK by BT in December 1992, with little publicity. It connects to existing 999 circuits. The GSM standard mandates that the user of a GSM phone can dial 112 without unlocking the keypad, a feature that can save time in emergencies but that also causes some accidental calls. However, a valid SIM card is required to make a 999/112 emergency call in the UK.
On 6 October 1998, BT introduced a new system whereby all the information about the location of the calling telephone was transmitted electronically to the relevant service rather than having to read it out (with the possibility of errors). This system is called EISEC (Enhanced Information Service for Emergency Calls).
On 30 December, 2006, West Midlands Ambulance Service gave Christmas 2006 examples of inappropriate uses of 999 during the festive period, including: a man who could not find his trousers; a man who "couldn't walk from too much dancing"; a man with a finger injury he had sustained two days earlier; and an 18-year-old man who had a toothache.
It has been reported that on some networks in the UK, and in Ireland dialing 9-1-1 will forward you to the emergency line as well. Despite that 911 is not the official number in those locations and can not be relied upon in case of emergency.
## 999 services
In the UK it is an all-service number, meaning that it should be called in any situations where state-run emergency services are needed. The three main and best-known services are police, fire & rescue services and ambulance/paramedics. Other available services include coastguards, mountain rescue and cave rescue (where locally relevant). Some situations such as a major car accident or a terrorist attack (including nuclear, biological, or chemical attacks) will require multiple and/or specialist services but the first point of call for reporting such incidents from the general public is still the 999 system. In some situations there will be specific instructions on nearby signs to notify some other authority of an emergency before calling 999. For example there are notices on bridges carrying railways over roads telling people that, if they see a road vehicle striking the bridge, they should call the railway authority (on a given number) first and then call 999 to inform the police.
In the UK, the number is operated by BT, Cable & Wireless, Kingston Communications and Global Crossing. These organisations forward calls to the appropriate emergency service for the location and incident; all calls to the number are made free of charge. The operation of 999 is coordinated by the 999 liaison committee.
Since May 2006 a new non-emergency telephone number 101 has been available, initially in Hampshire, and then in Northumbria, Cardiff, South Yorkshire, and 'Leicester and Rutland' for calls to the police that did not require an immediate police response. It was planned to be rolled out in the summer of 2008, but funding was pulled by the Home Office during 2007, causing some of the 101 lines to close. | 9-9-9
999 is the United Kingdom's and Ireland's emergency telephone number and Poland's medical emergency number. They are all used alongside the EU standard 112.[1]
999 is also the emergency telephone number in some Commonwealth countries including Bangladesh, Botswana, Ghana, Malaysia and Singapore (the rest use a variety of numbers, including 9-1-1). It is also used in the United Arab Emirates, Hong Kong, Macau, Bahrain and Qatar.
# Hong Kong
The 999 was introduced to Hong Kong during British rule and continues to be used following the handover in 1997.
# Malaysia
The 999 emergency services in Malaysia is manned by about 138 telephonists from Telekom Malaysia. On-going upgrading works are taking place to introduce the Computer-Telephony Integration (CTI) for hospital exchanges, digital mapping to track the callers' locations and Computer Assisted Despatching (CAD) for online connectivity among the agencies providing the emergency services in the country. All calls to the number are made free of charge.
# Poland
The 112 emergency number is an all-service number in Poland like in the other EU states, but old numbers that were traditionally designated for emergencies are still in use parallel to 112. Those are:
- 999 for medical emergency
- 998 for fire emergency
- 997 for Police
# United Kingdom
The 999 service was introduced on 30 June 1937 in the London area. 999 was chosen because of the need for the code to be able to be dialled from A/B button public telephones. The telephone dial (GPO Dial No 11) used with these coin-boxes allowed the digit '0' to be dialled without inserting any money, and it was very easy to adapt the dial to dial '9' without inserting money. All other digits from 2 to 8 were in use somewhere in the UK as the initial digits for subscribers' telephone numbers and hence could not easily be used. Had any other digits been used, other digits between that one and the already free '0' would also have been able to be dialled free of charge. No other telephone numbers existed using combinations of the digits '9' and '0' (other than one in Woolwich) therefore there would be no unauthorised 'free' calls. Thus the easy conversion of coin-box dial was the deciding factor and the fact that 999 was not used anywhere, other than for accessing the occasional 'position 9' of an Engineering Test Desk in the telephone exchange. Numbers beginning with 1 were excluded for other technical reasons - for example, 111 could be dialled by accident by wires making contact.[2] Access to the emergency service is provided for the hearing impaired via Textphone and use of the national 'typetalk' relay service. The number is 18000, having previously been 0800 112999.
Since the introduction of mobile phones, the choice of the number 999 has become a particular problem for UK emergency services,[3] as same-digit sequences are most likely dialled by accident due to vibrations and other objects colliding with a keypad. This problem is less of a concern with emergency numbers that use two different digits (e.g., 112, 911).
The pan-European 112 code was introduced in the UK by BT in December 1992[citation needed], with little publicity. It connects to existing 999 circuits. The GSM standard mandates that the user of a GSM phone can dial 112 without unlocking the keypad, a feature that can save time in emergencies but that also causes some accidental calls. However, a valid SIM card is required to make a 999/112 emergency call in the UK.[4]
On 6 October 1998, BT introduced a new system whereby all the information about the location of the calling telephone was transmitted electronically to the relevant service rather than having to read it out (with the possibility of errors). This system is called EISEC (Enhanced Information Service for Emergency Calls).
On 30 December, 2006, West Midlands Ambulance Service gave Christmas 2006 examples of inappropriate uses of 999 during the festive period, including: a man who could not find his trousers; a man who "couldn't walk from too much dancing"; a man with a finger injury he had sustained two days earlier; and an 18-year-old man who had a toothache.[5]
It has been reported that on some networks in the UK, and in Ireland dialing 9-1-1 will forward you to the emergency line as well.[6] Despite that 911 is not the official number in those locations and can not be relied upon in case of emergency.[7]
## 999 services
In the UK it is an all-service number, meaning that it should be called in any situations where state-run emergency services are needed. The three main and best-known services are police, fire & rescue services and ambulance/paramedics. Other available services include coastguards, mountain rescue and cave rescue (where locally relevant). Some situations such as a major car accident or a terrorist attack (including nuclear, biological, or chemical attacks) will require multiple and/or specialist services but the first point of call for reporting such incidents from the general public is still the 999 system. In some situations there will be specific instructions on nearby signs to notify some other authority of an emergency before calling 999. For example there are notices on bridges carrying railways over roads telling people that, if they see a road vehicle striking the bridge, they should call the railway authority (on a given number) first and then call 999 to inform the police.
In the UK, the number is operated by BT, Cable & Wireless, Kingston Communications and Global Crossing. These organisations forward calls to the appropriate emergency service for the location and incident; all calls to the number are made free of charge. The operation of 999 is coordinated by the 999 liaison committee.
## 101
Since May 2006 a new non-emergency telephone number 101 has been available, initially in Hampshire, and then in Northumbria, Cardiff, South Yorkshire, and 'Leicester and Rutland' for calls to the police that did not require an immediate police response.[8] It was planned to be rolled out in the summer of 2008,[9] but funding was pulled by the Home Office during 2007, causing some of the 101 lines to close.[10][11][12] | https://www.wikidoc.org/index.php/9-9-9 | |
b1b0cae703b8882108b8fbb171ad5338209aa7d3 | wikidoc | A2ML1 | A2ML1
Alpha-2-macroglobulin-like 1 abbreviated as α2ML1 is a protein that in humans is encoded by the A2ML1 gene. α2ML1 is a large, 180 kDa protein found in the epidermis. It is able to the inhibit the chymotryptic activity of KLK7.
# Function
This gene encodes a member of the alpha-macroglobulin superfamily. The encoded protein acts as an inhibitor for several proteases, and has been reported as the p170 antigen recognized by autoantibodies in the autoimmune disease paraneoplastic pemphigus (PNP). Alternative splicing results in multiple transcript variants.
# Clinical significance
Mutations in A2ML1 are associated to Noonan-like syndrome . | A2ML1
Alpha-2-macroglobulin-like 1 abbreviated as α2ML1 is a protein that in humans is encoded by the A2ML1 gene.[1] α2ML1 is a large, 180 kDa protein found in the epidermis. It is able to the inhibit the chymotryptic activity of KLK7.[2]
# Function
This gene encodes a member of the alpha-macroglobulin superfamily. The encoded protein acts as an inhibitor for several proteases, and has been reported as the p170 antigen recognized by autoantibodies in the autoimmune disease paraneoplastic pemphigus (PNP).[3] Alternative splicing results in multiple transcript variants.[1]
# Clinical significance
Mutations in A2ML1 are associated to Noonan-like syndrome .[4] | https://www.wikidoc.org/index.php/A2ML1 | |
6b6c410ed467a89c5fe63262057970cc293790bd | wikidoc | ABCA1 | ABCA1
ATP-binding cassette transporter ABCA1 (member 1 of human transporter sub-family ABCA), also known as the cholesterol efflux regulatory protein (CERP) is a protein which in humans is encoded by the ABCA1 gene. This transporter is a major regulator of cellular cholesterol and phospholipid homeostasis.
# Tangier Disease
It was discovered that a mutation in the ABCA1 protein is responsible for causing Tangier's Disease by several groups in 1998. Gerd Schmitz's group in Germany and Michael Hayden's group in British Columbia were using standard genetics techniques and DNA from family pedigrees to locate the mutation. Richard Lawn's group at CV Therapeutics in Palo Alto, CA used cDNA microarrays, which were relatively new at the time, to assess gene expression profiles from cell lines created from normal and affected individuals. They showed cell lines from patients with Tangier's disease showed differential regulation of the ABCA1 gene. Subsequent sequencing of the gene identified the mutations. This group received an award from the American Heart Association for their discovery. Tangier disease has been identified in nearly 100 patients worldwide, and patients have a broad range of biochemical and clinical phenotypes as over 100 different mutations have been identified in ABCA1 resulting in the disease.
# Function
The membrane-associated protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intracellular membranes. ABC genes are divided into seven distinct subfamilies (ABCA, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the ABCA subfamily. Members of the ABCA subfamily comprise the only major ABC subfamily found exclusively in multicellular eukaryotes. With cholesterol as its substrate, this protein functions as a cholesterol efflux pump in the cellular lipid removal pathway.
While the complete 3D-structure of ABCA1 remains relatively unknown, there has been some determination of the c-terminus. The ABCA1 c-terminus contains a PDZ domain, responsible for mediating protein-protein interactions, as well as a VFVNFA motif essential for lipid efflux activity.
# Physiological role
ABCA1 mediates the efflux of cholesterol and phospholipids to lipid-poor apolipoproteins (apo-A1 and apoE), which then form nascent high-density lipoproteins (HDL). It also mediates the transport of lipids between Golgi and cell membrane. Since this protein is needed throughout the body it is expressed ubiquitously as a 220-kDa protein. It is present in higher quantities in tissues that shuttle or are involved in the turnover of lipids such as the liver, the small intestine and adipose tissue.
Factors that act upon the ABCA1 transporter's expression or its posttranslational modification are also molecules that are involved in its subsequent function like fatty acids, cholesterol and also cytokines and cAMP. Other endogenous metabolites more loosely related to the ABCA1 functions are also reported to influence the expression of this transporter, including glucose and bilirubin.
Interactions between members of the apoliprotein family and ABCA1 activate multiple signalling pathways, including the JAK-STAT, PKA, and PKC pathways
Overexpression of ABCA1 has been reported to induce resistance to the anti-inflammatory diarylheptanoid antioxidant curcumin.
Downregulation of ABCA1 in senescent macrophages disrupts the cell's ability to remove cholesterol from its cytoplasm, leading the cells to promote pathologic atherogenesis (blood vessel thickening/hardening) which "plays a central role in common age-associated diseases such as atherosclerosis, cancer, and macular degeneration" Knockout mouse models of AMD treated with agonists that increase ABCA1 in loss of function and gain of function experiments demonstrated the protective role of elevating ABCA1 in regulating angiogenesis in eye disease. Human data from patients and controls were used to demonstrate the translation of mouse findings in human disease.
# Clinical significance
Mutations in this gene have been associated with Tangier disease and familial high-density lipoprotein deficiency. ABCA1 has been shown to be reduced in Tangier disease which features physiological deficiencies of HDL.
Leukocytes ABCA1 gene expression is upregulated in postmenopausal women receiving hormone replacement therapy (HRP).
# Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles.
- ↑ The interactive pathway map can be edited at WikiPathways: "Statin_Pathway_WP430"..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"\"""\"""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{display:none;font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}
# Interactions
ABCA1 has been shown to interact with:
- APOA1,
- APOE,
- FADD,
- SNTB2, and
- XPC. | ABCA1
ATP-binding cassette transporter ABCA1 (member 1 of human transporter sub-family ABCA), also known as the cholesterol efflux regulatory protein (CERP) is a protein which in humans is encoded by the ABCA1 gene.[1] This transporter is a major regulator of cellular cholesterol and phospholipid homeostasis.
# Tangier Disease
It was discovered that a mutation in the ABCA1 protein is responsible for causing Tangier's Disease by several groups in 1998. Gerd Schmitz's group in Germany[2] and Michael Hayden's group in British Columbia[3] were using standard genetics techniques and DNA from family pedigrees to locate the mutation. Richard Lawn's group at CV Therapeutics in Palo Alto, CA used cDNA microarrays, which were relatively new at the time, to assess gene expression profiles from cell lines created from normal and affected individuals.[4] They showed cell lines from patients with Tangier's disease showed differential regulation of the ABCA1 gene. Subsequent sequencing of the gene identified the mutations. This group received an award from the American Heart Association for their discovery.[5] Tangier disease has been identified in nearly 100 patients worldwide, and patients have a broad range of biochemical and clinical phenotypes as over 100 different mutations have been identified in ABCA1 resulting in the disease.[6]
# Function
The membrane-associated protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intracellular membranes. ABC genes are divided into seven distinct subfamilies (ABCA, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the ABCA subfamily. Members of the ABCA subfamily comprise the only major ABC subfamily found exclusively in multicellular eukaryotes. With cholesterol as its substrate, this protein functions as a cholesterol efflux pump in the cellular lipid removal pathway.[7][8]
While the complete 3D-structure of ABCA1 remains relatively unknown, there has been some determination of the c-terminus. The ABCA1 c-terminus contains a PDZ domain, responsible for mediating protein-protein interactions, as well as a VFVNFA motif essential for lipid efflux activity.[6]
# Physiological role
ABCA1 mediates the efflux of cholesterol and phospholipids to lipid-poor apolipoproteins (apo-A1 and apoE), which then form nascent high-density lipoproteins (HDL). It also mediates the transport of lipids between Golgi and cell membrane. Since this protein is needed throughout the body it is expressed ubiquitously as a 220-kDa protein. It is present in higher quantities in tissues that shuttle or are involved in the turnover of lipids such as the liver, the small intestine and adipose tissue.[9]
Factors that act upon the ABCA1 transporter's expression or its posttranslational modification are also molecules that are involved in its subsequent function like fatty acids, cholesterol and also cytokines and cAMP.[10] Other endogenous metabolites more loosely related to the ABCA1 functions are also reported to influence the expression of this transporter, including glucose and bilirubin.[11][12]
Interactions between members of the apoliprotein family and ABCA1 activate multiple signalling pathways, including the JAK-STAT, PKA, and PKC pathways[13]
Overexpression of ABCA1 has been reported to induce resistance to the anti-inflammatory diarylheptanoid antioxidant curcumin.[14]
Downregulation of ABCA1 in senescent macrophages disrupts the cell's ability to remove cholesterol from its cytoplasm, leading the cells to promote pathologic atherogenesis (blood vessel thickening/hardening) which "plays a central role in common age-associated diseases such as atherosclerosis, cancer, and macular degeneration"[15] Knockout mouse models of AMD treated with agonists that increase ABCA1 in loss of function and gain of function experiments demonstrated the protective role of elevating ABCA1 in regulating angiogenesis in eye disease. Human data from patients and controls were used to demonstrate the translation of mouse findings in human disease.[16]
# Clinical significance
Mutations in this gene have been associated with Tangier disease and familial high-density lipoprotein deficiency. ABCA1 has been shown to be reduced in Tangier disease which features physiological deficiencies of HDL.[17][18]
Leukocytes ABCA1 gene expression is upregulated in postmenopausal women receiving hormone replacement therapy (HRP).[19]
# Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles. [§ 1]
- ↑ The interactive pathway map can be edited at WikiPathways: "Statin_Pathway_WP430"..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"\"""\"""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{display:none;font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}
# Interactions
ABCA1 has been shown to interact with:
- APOA1,[20]
- APOE,
- FADD,[21]
- SNTB2,[22] and
- XPC.[23] | https://www.wikidoc.org/index.php/ABCA1 | |
771484e1178855a1d598b91abb82301291e75dce | wikidoc | ABCA3 | ABCA3
ATP-binding cassette sub-family A member 3 is a protein that in humans is encoded by the ABCA3 gene.
The membrane-associated protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intracellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the ABC1 subfamily. Members of the ABC1 subfamily comprise the only major ABC subfamily found exclusively in multicellular eukaryotes. The full transporter encoded by this gene may be involved in development of resistance to xenobiotics and engulfment during programmed cell death.
# Clinical significance
Mutations in ABCA3 are associated to cataract-microcornea syndrome .
It is associated with Surfactant metabolism dysfunction type 3. | ABCA3
ATP-binding cassette sub-family A member 3 is a protein that in humans is encoded by the ABCA3 gene.[1][2]
The membrane-associated protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intracellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the ABC1 subfamily. Members of the ABC1 subfamily comprise the only major ABC subfamily found exclusively in multicellular eukaryotes. The full transporter encoded by this gene may be involved in development of resistance to xenobiotics and engulfment during programmed cell death.[2]
# Clinical significance
Mutations in ABCA3 are associated to cataract-microcornea syndrome .[3]
It is associated with Surfactant metabolism dysfunction type 3. | https://www.wikidoc.org/index.php/ABCA3 | |
2da597db20e369cb93fbc78dd84a595d964a7e5a | wikidoc | ABCA4 | ABCA4
ATP-binding cassette, sub-family A (ABC1), member 4, also known as ABCA4 or ABCR, is a protein which in humans is encoded by the ABCA4 gene.
ABCA4 is a member of the ATP-binding cassette transporter gene sub-family A (ABC1) found exclusively in multicellular eukaryotes. The gene was first cloned and characterized in 1997 as a gene that causes Stargardt disease, an autosomal recessive disease that causes macular degeneration. The ABCA4 gene transcribes a large retina-specific protein with two transmembrane domains (TMD), two glycosylated extracellular domains (ECD), and two nucleotide-binding domains (NBD). The ABCA4 protein is almost exclusively expressed in retina localizing in outer segment disk edges of rod photoreceptors.
# Structure
Previously known as the photoreceptor rim protein RmP or ABCR, the recently proposed ABCA4 structure consists of two transmembrane domains (TMDs), two large glycosylated extracytosolic domains (ECD), and two internal nucleotide binding domains (NBDs). One TMD spans across membranes with six units of protein linked together to form a domain. The TMDs are usually not conserved across genomes due to its specificity and diversity in function as channels or ligand-binding controllers. However, NBDs are highly conserved across different genomes—an observation consistent with which it binds and hydrolyzes ATP. NBD binds adenosine triphosphate molecules (ATP) to utilize the high-energy inorganic phosphate to carry out change in conformation of the ABC transporter. Transcribed ABCA4 forms into a heterodimer: the two dimerized compartments of the channel are different from each other. When TMDs are situated in a membrane, they form a barrel-like structure permeable to retinoid ligands and control channel access to its binding sites. Once an ATP is hydrolized at the NBDs of the channel, NBDs are brought together to tilt and modify TMDs to modulate ligand binding to the channel. A recently proposed model of retinoid transfer occurring as a result of alternating exposure of external and internal TMD ligand binding sites, all controlled by binding of ATP, is based on recent structural analyses of bacterial ABC transporters.
# Function
ABCR is localized to outer segment disk edges of rods and cones. ABCR is expressed much less than rhodopsin, approximately at 1:120. Comparisons between mammalian ABCA4 to other ABCs, cellular localization of ABCA4, and analyses of ABCA4 knockout mice suggest that ABCA4 may function as an inward-directed retinoid flippase. Flippase is a transmembrane protein that "flips" its conformation to transport materials across a membrane. In the case of ABCA4, the flippase facilitates transfer of N-retinyl-phosphatidylethanolamine (NR-PE), a covalent adduct of all-trans retinaldehyde (ATR) with phosphatidylethanolamine (PE), trapped inside the disk as charged species out to the cytoplasmic surface. Once transported, ATR is reduced to vitamin A and then transferred to retinal pigment epithelium to be recycled into 11-cis-retinal. This alternating access-release model for ABCA4 has four steps: (1) binding of ATP to an NBD to bring two NBDs together and expose outer vestibule high affinity binding site located in TMD, (2) binding of NR-PE/ATR on extracellular side of the channel, (3) ATP hydrolysis promoting gate opening and movement of NR-PE/ATR across the membrane to the low-affinity binding site on the intracellular portion of TMD, and (4) release of adenosine diphosphate (ADP) and inorganic phosphate (Pi) to release the bound ligand. The channel is then ready to transfer another molecule of NR-PE/ATR again.
The ABCR -/- knockout mouse has delayed dark adaptation but normal final rod threshold relative to controls. This suggests bulk transmembrane diffusion pathways that remove ATR/NR-PE from extracellular membranes. After bleaching the retina with strong light, ATR/NR-PE accumulates significantly in outer segments. This accumulation leads to formation of toxic cationic bis-pyridinium salt, N-retinylidene-N-retinyl-ethanolamine (A2E), which causes human dry and wet age-related macular degeneration. From this experiment, it was concluded that ABCR has a significant role in clearing accumulation of ATR/NR-PE to prevent formation of A2E in extracellular photoreceptor surfaces during bleach recovery.
# Clinical significance
Mutations in ABCA4 gene are known to cause the autosomal-recessive disease Stargardt macular dystrophy (STGD), which is a hereditary juvenile macular degeneration disease causing progressive loss of photoreceptor cells. STGD is characterized by reduced visual acuity and color vision, loss of central (macular) vision, delayed dark adaptation, and accumulation of autoflourescent RPE lipofuscin. Removal of NR-PE/ATR appears to be significant in normal bleach recovery and to mitigate persistent opsin signaling that causes photoreceptors to degenerate. ABCA4 also mitigates long-term effects of accumulation of ATR that results in irreversible ATR binding to a second molecule of ATR and NR-PE to form dihydro-N-retinylidene-N-retinyl-phosphatidyl-ethanolamine (A2PE-H2). A2PE-H2 traps ATR and accumulates in outer segments to further oxidize into N-retinylidene-N-retinyl-phosphatidyl-ethanolamine (A2PE). After diurnal disk-shedding and phagocytosis of outer segment by RPE cells, A2PE is hydrolyzed inside the RPE phagolysosome to form A2E. Accumulation of A2E causes toxicity at the primary RPE level and secondary photoreceptor destruction in macular degenerations.
Additional diseases that may link to mutations in ABCA4 include fundus flavimaculatus, cone-rod dystrophy, retinitis pigmentosa, and age-related macular degeneration.
The GENEVA Cleft Consortium study first identified ABCA4 as being associated with cleft lip and/or cleft palate with multiple markers giving evidence of linkage and association at the genome-wide significance level. Although SNPs in this gene are associated with cleft lip/palate there is no functional or expression data to support it as the causal gene which may, instead, lie in a region adjacent to ABCA4. A combination of genome wide association, rare coding sequence variants, craniofacial specific expression, and interactions with IRF6 support a role for the adjacent ARHGAP29 gene to be the likely causal gene playing a role in nonsyndromic cleft lip and/or palate. | ABCA4
ATP-binding cassette, sub-family A (ABC1), member 4, also known as ABCA4 or ABCR, is a protein which in humans is encoded by the ABCA4 gene.[1][2][3]
ABCA4 is a member of the ATP-binding cassette transporter gene sub-family A (ABC1) found exclusively in multicellular eukaryotes.[1] The gene was first cloned and characterized in 1997 as a gene that causes Stargardt disease, an autosomal recessive disease that causes macular degeneration.[4] The ABCA4 gene transcribes a large retina-specific protein with two transmembrane domains (TMD), two glycosylated extracellular domains (ECD), and two nucleotide-binding domains (NBD). The ABCA4 protein is almost exclusively expressed in retina localizing in outer segment disk edges of rod photoreceptors.[5]
# Structure
Previously known as the photoreceptor rim protein RmP or ABCR, the recently proposed ABCA4 structure consists of two transmembrane domains (TMDs), two large glycosylated extracytosolic domains (ECD), and two internal nucleotide binding domains (NBDs). One TMD spans across membranes with six units of protein linked together to form a domain. The TMDs are usually not conserved across genomes due to its specificity and diversity in function as channels or ligand-binding controllers. However, NBDs are highly conserved across different genomes—an observation consistent with which it binds and hydrolyzes ATP. NBD binds adenosine triphosphate molecules (ATP) to utilize the high-energy inorganic phosphate to carry out change in conformation of the ABC transporter. Transcribed ABCA4 forms into a heterodimer: the two dimerized compartments of the channel are different from each other. When TMDs are situated in a membrane, they form a barrel-like structure permeable to retinoid ligands and control channel access to its binding sites.[6] Once an ATP is hydrolized at the NBDs of the channel, NBDs are brought together to tilt and modify TMDs to modulate ligand binding to the channel.[7] A recently proposed model of retinoid transfer occurring as a result of alternating exposure of external and internal TMD ligand binding sites, all controlled by binding of ATP, is based on recent structural analyses of bacterial ABC transporters.
# Function
ABCR is localized to outer segment disk edges of rods and cones. ABCR is expressed much less than rhodopsin, approximately at 1:120. Comparisons between mammalian ABCA4 to other ABCs, cellular localization of ABCA4, and analyses of ABCA4 knockout mice suggest that ABCA4 may function as an inward-directed retinoid flippase.[8] Flippase is a transmembrane protein that "flips" its conformation to transport materials across a membrane. In the case of ABCA4, the flippase facilitates transfer of N-retinyl-phosphatidylethanolamine (NR-PE), a covalent adduct of all-trans retinaldehyde (ATR) with phosphatidylethanolamine (PE), trapped inside the disk as charged species out to the cytoplasmic surface.[9] Once transported, ATR is reduced to vitamin A and then transferred to retinal pigment epithelium to be recycled into 11-cis-retinal. This alternating access-release model for ABCA4 has four steps: (1) binding of ATP to an NBD to bring two NBDs together and expose outer vestibule high affinity binding site located in TMD, (2) binding of NR-PE/ATR on extracellular side of the channel, (3) ATP hydrolysis promoting gate opening and movement of NR-PE/ATR across the membrane to the low-affinity binding site on the intracellular portion of TMD, and (4) release of adenosine diphosphate (ADP) and inorganic phosphate (Pi) to release the bound ligand. The channel is then ready to transfer another molecule of NR-PE/ATR again.
The ABCR -/- knockout mouse has delayed dark adaptation but normal final rod threshold relative to controls.[8] This suggests bulk transmembrane diffusion pathways that remove ATR/NR-PE from extracellular membranes. After bleaching the retina with strong light, ATR/NR-PE accumulates significantly in outer segments. This accumulation leads to formation of toxic cationic bis-pyridinium salt, N-retinylidene-N-retinyl-ethanolamine (A2E), which causes human dry and wet age-related macular degeneration.[10] From this experiment, it was concluded that ABCR has a significant role in clearing accumulation of ATR/NR-PE to prevent formation of A2E in extracellular photoreceptor surfaces during bleach recovery.
# Clinical significance
Mutations in ABCA4 gene are known to cause the autosomal-recessive disease Stargardt macular dystrophy (STGD), which is a hereditary juvenile macular degeneration disease causing progressive loss of photoreceptor cells. STGD is characterized by reduced visual acuity and color vision, loss of central (macular) vision, delayed dark adaptation, and accumulation of autoflourescent RPE lipofuscin.[10] Removal of NR-PE/ATR appears to be significant in normal bleach recovery and to mitigate persistent opsin signaling that causes photoreceptors to degenerate. ABCA4 also mitigates long-term effects of accumulation of ATR that results in irreversible ATR binding to a second molecule of ATR and NR-PE to form dihydro-N-retinylidene-N-retinyl-phosphatidyl-ethanolamine (A2PE-H2). A2PE-H2 traps ATR and accumulates in outer segments to further oxidize into N-retinylidene-N-retinyl-phosphatidyl-ethanolamine (A2PE). After diurnal disk-shedding and phagocytosis of outer segment by RPE cells, A2PE is hydrolyzed inside the RPE phagolysosome to form A2E.[10] Accumulation of A2E causes toxicity at the primary RPE level and secondary photoreceptor destruction in macular degenerations.
Additional diseases that may link to mutations in ABCA4 include fundus flavimaculatus, cone-rod dystrophy, retinitis pigmentosa, and age-related macular degeneration.
The GENEVA Cleft Consortium study first identified ABCA4 as being associated with cleft lip and/or cleft palate with multiple markers giving evidence of linkage and association at the genome-wide significance level.[11] Although SNPs in this gene are associated with cleft lip/palate there is no functional or expression data to support it as the causal gene which may, instead, lie in a region adjacent to ABCA4.[12] A combination of genome wide association, rare coding sequence variants, craniofacial specific expression, and interactions with IRF6 support a role for the adjacent ARHGAP29 gene to be the likely causal gene playing a role in nonsyndromic cleft lip and/or palate.[13] | https://www.wikidoc.org/index.php/ABCA4 | |
067fd19cde9477c99abd8e04d437f3d990f213e8 | wikidoc | ABCA5 | ABCA5
ATP-binding cassette, sub-family A (ABC1), member 5 is a protein that in humans is encoded by the ABCA5 gene.
# Function
The membrane-associated protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecule across extra- and intracellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, and White). This encoded protein is a member of the ABC1 subfamily. Members of the ABC1 subfamily comprise the only major ABC subfamily found exclusively in multicellular eukaryotes. This gene is clustered among 4 other ABC1 family members on 17q24, but neither the substrate nor the function of this gene is known. Alternative splicing of this gene results in several transcript variants; however, not all variants have been fully described. .
# Clinical significance
Mutations in ABCA5 cause excessive hair overgrowth . | ABCA5
ATP-binding cassette, sub-family A (ABC1), member 5 is a protein that in humans is encoded by the ABCA5 gene.[1]
# Function
The membrane-associated protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecule across extra- and intracellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, and White). This encoded protein is a member of the ABC1 subfamily. Members of the ABC1 subfamily comprise the only major ABC subfamily found exclusively in multicellular eukaryotes. This gene is clustered among 4 other ABC1 family members on 17q24, but neither the substrate nor the function of this gene is known. Alternative splicing of this gene results in several transcript variants; however, not all variants have been fully described. [provided by RefSeq, Jul 2008].
# Clinical significance
Mutations in ABCA5 cause excessive hair overgrowth .[2] | https://www.wikidoc.org/index.php/ABCA5 | |
ee21dc3921a4c743d6c39bbe6a4c469fe549b31e | wikidoc | ABCA7 | ABCA7
ATP-binding cassette sub-family A member 7 is a protein that in humans is encoded by the ABCA7 gene.
# Function
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies: ABC1, MDR/TAP, CFTR/MRP, ALD (adrenoleukodystrophy), OABP, GCN20, and White. This protein is a member of the ABC1 subfamily. Members of the ABC1 subfamily comprise the only major ABC subfamily found exclusively in multicellular eukaryotes. This full transporter has been detected predominantly in myelo-lymphatic tissues with the highest expression in peripheral leukocytes, thymus, spleen, and bone marrow. The function of this protein is not yet known; however, the expression pattern suggests a role in lipid homeostasis in cells of the immune system. Alternative splicing of this gene results in two transcript variants.
# Clinical significance
Protein-disrupting variants in ABCA7 have been shown to predispose to Alzheimer's disease. The Icelandic database of Decode Genetics has shown a doubled probability of developing Alzheimer's disease when inactive variants of the ABCA7 gene are present. | ABCA7
ATP-binding cassette sub-family A member 7 is a protein that in humans is encoded by the ABCA7 gene.[1]
# Function
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies: ABC1, MDR/TAP, CFTR/MRP, ALD (adrenoleukodystrophy), OABP, GCN20, and White. This protein is a member of the ABC1 subfamily. Members of the ABC1 subfamily comprise the only major ABC subfamily found exclusively in multicellular eukaryotes. This full transporter has been detected predominantly in myelo-lymphatic tissues with the highest expression in peripheral leukocytes, thymus, spleen, and bone marrow. The function of this protein is not yet known; however, the expression pattern suggests a role in lipid homeostasis in cells of the immune system. Alternative splicing of this gene results in two transcript variants.[1]
# Clinical significance
Protein-disrupting variants in ABCA7 have been shown to predispose to Alzheimer's disease.[2] The Icelandic database of Decode Genetics has shown a doubled probability of developing Alzheimer's disease when inactive variants of the ABCA7 gene are present.[3] | https://www.wikidoc.org/index.php/ABCA7 | |
39d656823a4feb91010ef33018b9e5d3d34f04bc | wikidoc | ABCB5 | ABCB5
ATP-binding cassette sub-family B member 5 also known as P-glycoprotein ABCB5 is a plasma membrane-spanning protein that in humans is encoded by the ABCB5 gene. ABCB5 is an ABC transporter and P-glycoprotein family member principally expressed in physiological skin and human malignant melanoma.
# Clinical significance
ABCB5 has been suggested to regulate skin progenitor cell fusion and mediate chemotherapeutic drug resistance in stem-like tumor cell subpopulations in human malignant melanoma. It is commonly over-expressed on circulating melanoma tumour cells. Furthermore, the ABCB5+ melanoma- initiating cells were demonstrated to express FLT1 (VEGFR1) receptor tyrosine kinase which was functionally required for efficient xenograft tumor formation, as demonstrated by shRNA knockdown experiments.
In colorectal cancer, ABCB5 was shown to act as a mediator of 5-FU patient chemoresistance, and had a further direct role in tumorigenesis shown by shRNA-mediated colorectal cancer cell-line ABCB5 knockdowns that impeded tumorigenesis in human-to-mouse xenografts. In melanoma, ABCB5 contributes to multi-drug chemotherapy resistance, and tumor growth, controlling a proinflammatory signaling circuit utilizing TLR4, IL-1β, IL8 and CXCR1 signaling involving reciprocal paracrine interactions between the melanoma stem cell and tumor bulk population (in a rheostat manner termed "cancer stem cell rheostasis"). ABCB5 was shown to maintain the slow-cycling melanoma stem cells using this cytokine signaling loop, which became more differentiated upon ABCB5 interference (e.g. WFDC1 melanocyte differentiation marker increased, cancer cells were faster growing in vitro, tumors were more pigmented), or CXCR1 blockade (slow-cycling ABCB5+ cells entered the cell-cycle).
In normal physiology ABCB5 is a functional marker for adult limbal stem cells of the cornea. ABCB5+ cells could regrow a human cornea on a mouse with limbal stem cell deficiency (LSCD - a blindness disease of the corneal limbus) while ABCB5- cells could not, indicating a therapeutic potential for treating some types of blindness. ABCB5 was further shown to be anti-apoptotic in these adult stem cells. | ABCB5
ATP-binding cassette sub-family B member 5 also known as P-glycoprotein ABCB5 is a plasma membrane-spanning protein that in humans is encoded by the ABCB5 gene.[1][2] ABCB5 is an ABC transporter and P-glycoprotein family member principally expressed in physiological skin and human malignant melanoma.[3][4][5]
# Clinical significance
ABCB5 has been suggested to regulate skin progenitor cell fusion and mediate chemotherapeutic drug resistance in stem-like tumor cell subpopulations in human malignant melanoma. It is commonly over-expressed on circulating melanoma tumour cells.[6][7] Furthermore, the ABCB5+ melanoma- initiating cells were demonstrated to express FLT1 (VEGFR1) receptor tyrosine kinase which was functionally required for efficient xenograft tumor formation, as demonstrated by shRNA knockdown experiments.[8]
In colorectal cancer, ABCB5 was shown to act as a mediator of 5-FU patient chemoresistance, and had a further direct role in tumorigenesis shown by shRNA-mediated colorectal cancer cell-line ABCB5 knockdowns that impeded tumorigenesis in human-to-mouse xenografts.[9] In melanoma, ABCB5 contributes to multi-drug chemotherapy resistance, and tumor growth, controlling a proinflammatory signaling circuit utilizing TLR4, IL-1β, IL8 and CXCR1 signaling involving reciprocal paracrine interactions between the melanoma stem cell and tumor bulk population (in a rheostat manner termed "cancer stem cell rheostasis"). ABCB5 was shown to maintain the slow-cycling melanoma stem cells using this cytokine signaling loop, which became more differentiated upon ABCB5 interference (e.g. WFDC1 melanocyte differentiation marker increased, cancer cells were faster growing in vitro, tumors were more pigmented), or CXCR1 blockade (slow-cycling ABCB5+ cells entered the cell-cycle).[10]
In normal physiology ABCB5 is a functional marker for adult limbal stem cells of the cornea. ABCB5+ cells could regrow a human cornea on a mouse with limbal stem cell deficiency (LSCD - a blindness disease of the corneal limbus) while ABCB5- cells could not, indicating a therapeutic potential for treating some types of blindness. ABCB5 was further shown to be anti-apoptotic in these adult stem cells.[11] | https://www.wikidoc.org/index.php/ABCB5 | |
023cbf0a044aac50dda024b08f4369007d1a9869 | wikidoc | ABCB7 | ABCB7
ATP-binding cassette sub-family B member 7, mitochondrial is a protein that in humans is encoded by the ABCB7 gene.
# Function
The membrane-associated protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the MDR/TAP subfamily. Members of the MDR/TAP subfamily are involved in multidrug resistance as well as antigen presentation. This gene encodes a half-transporter involved in the transport of heme from the mitochondria to the cytosol. With iron/sulfur cluster precursors as its substrates, this protein may play a role in metal homeostasis.
# Clinical significance
Mutations in this gene have been implicated in X-linked sideroblastic anemia with ataxia.
# Interactions
ABCB7 has been shown to interact with Ferrochelatase. | ABCB7
ATP-binding cassette sub-family B member 7, mitochondrial is a protein that in humans is encoded by the ABCB7 gene.[1][2]
# Function
The membrane-associated protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the MDR/TAP subfamily. Members of the MDR/TAP subfamily are involved in multidrug resistance as well as antigen presentation. This gene encodes a half-transporter involved in the transport of heme from the mitochondria to the cytosol. With iron/sulfur cluster precursors as its substrates, this protein may play a role in metal homeostasis.
# Clinical significance
Mutations in this gene have been implicated in X-linked sideroblastic anemia with ataxia.[2]
# Interactions
ABCB7 has been shown to interact with Ferrochelatase.[3] | https://www.wikidoc.org/index.php/ABCB7 | |
a8dc47c102370d1f26fc77e27904d5429f814a68 | wikidoc | ABCC1 | ABCC1
Multidrug resistance-associated protein 1 (MRP1) is a protein that in humans is encoded by the ABCC1 gene.
# Function
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra-and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This full transporter is a member of the MRP subfamily which is involved in multi-drug resistance. This protein functions as a multispecific organic anion transporter, with oxidized glutathione, cysteinyl leukotrienes, and activated aflatoxin B1 as substrates. This protein also transports glucuronides and sulfate conjugates of steroid hormones and bile salts. Alternative splicing by exon deletion results in several splice variants but maintains the original open reading frame in all forms.
# Structure
ABCC1 is a 190 kDa protein that contains two membrane-spanning domains of hydrophobic nature and two nucleotide binding domains. Each membrane-spanning domain is made up of six α-helices. In addition, the protein also contains a third membrane-spanning domain that sets it apart from other transporters within the ATP-binding cassette family of transporters. The two nucleotide binding domains have a functional asymmetry that plays a significant role in the ability of ATP to power the transporter. The first nucleotide binding domain, which is delegated NBD1, is responsible for the strong attraction of ATP to the transporter. The second nucleotide binding domain, NBD2, is the domain responsible for the hydrolysis of ATP. This asymmetry is specific to the C subfamily of ABC transporters and is generally not found in other transporters.
ABCC1 is a highly conserved gene with polymorphisms occurring at very low frequencies of less than five percent. Polymorphisms in this gene are generally found in the form of a single-nucleotide polymorphism (SNP). The greatest ethnic differences in polymorphisms within the ABCC1 are found between Caucasian and Asian populations. There are multiple examples of single nucleotide polymorphisms that are shared among Asian populations but not found in Caucasian populations and vice versa.
# Genomic location and tissue expression
The ABCC1 Predator gene, the gene that encodes the ABCC1 protein, is found on chromosome 16 within the nucleus. The protein resides intracellularly on the basolateral side of the plasma membrane which differs from other ATP-binding cassette transporters that are found on the apical side of the membrane. While ABCC1 is generally found throughout most tissues in humans, it is particularly prevalent in the lungs, spleen, testes, kidneys, placenta, thyroid, bladder, and adrenal glands. It is also found in the endothelium cells of the blood-brain barrier.
# Clinical significance
## Effect of polymorphisms
Certain polymorphisms in the ABCC1 gene have been shown to be connected with an increased susceptibility to certain types of cancer. A G2168A polymorphism and polymorphisms found in the 3'-UTR region of the gene have been shown to have a connection with increased susceptibility to lung cancer, especially in Chinese populations. Carriers of the G2168A polymorphism contract lung cancer at a rate nearly four times higher than those individuals that do not have the mutation in the gene. Polymorphisms within the ABCC1 gene also tend to have a substantial effect on the severity of a disease. Examples of these diseases includes cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD). In reference to cystic fibrosis, individuals with a G-260C polymorphism in the 5'-UTR area of the ABCC1 gene tended to have a much more severe case of cystic fibrosis than individuals with the wild-type gene. Individuals with chronic obstructive pulmonary disorder were impacted by two polymorphisms in the ABCC1 gene. If an individual had a 3'-UTR T866A polymorphism, they generally had a less severe case of COPD marked by less inflammation in their airways. On the other hand, an individual with a 3'-UTR G3361A polymorphism generally had a more severe case of COPD that was accompanied by a greater amount of inflammation in their airways.
## Alzheimer's disease
The ATP-binding cassette protein ABCC1 has received attention in the last decade due to its possible connection with Alzheimer’s disease. One of the more prominent signs of Alzheimer's disease is the accumulation of β-amyloid proteins in the brain. As these proteins accumulate, they begin to form plaques that interfere with signaling between cells of the nervous system found within the brain. Due to its presence in the choroid plexus and blood-brain barrier and its ability to transport multiple kinds of molecules out of cells, ABCC1 has been a point of interest in many Alzheimer's disease studies. The transporter protein has been shown to decrease β-amyloid accumulation by nearly 80 percent when activated, leading researchers to further investigation on its use in future treatments of Alzheimer's and other neurological disorders.
## Role in cancer
ABCC1 plays a role in the multidrug resistance of cancerous tumor cells due to its ability to transport many chemotherapeutic drugs out of the cells. The ABCC1 transporter protein is especially prevalent in neuroblastoma and cancer cells found in the lung, breast and prostate. In non-small cell lung carcinoma and small cell lung carcinoma, higher expression of ABCC1 was indicative of a reduced response to chemotherapeutic drugs and a lower rate of survival. Similar results were found in early-stage breast cancer where the increased expression of the transporter gene correlated with shorter times until a relapse occurred and lower rates of survival. In prostate cancer, expression of ABCC1 was found to increase with the stage of the disease while allowing resistance to chemotherapeutic drugs.
# Animal studies
Because of its significant role in the transportation of organic anion molecules and recent association with multiple illnesses including Alzheimer's disease (AD), the ABCC1 protein has become a potential drug target. In ABBC1 knockout mice, β-amyloid clearance is much lower than in wild-type mice that expressed the gene. Furthermore, in mouse models of AD, treatment with thiethylperazine, a drug that activates ABBC1, increases β-amyloid clearance and decreases in the amount of β-amyloid found in the brains.
St. John's wort, a substance containing the chemical hyperforin, has also been shown to have a positive effect on activity levels of ABCC1. In a study of the effects of St. John's wort on APP-tg mice, an extract of St. John's wort that contained decreased levels of hyperforin increased the activity of ABCC1 by 70 percent and led to decreased amounts of β-amyloid in the brain and increased cognitive function in the mice.
# Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles.
- ↑ The interactive pathway map can be edited at WikiPathways: "IrinotecanPathway_WP46359"..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"\"""\"""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{display:none;font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em} | ABCC1
Multidrug resistance-associated protein 1 (MRP1) is a protein that in humans is encoded by the ABCC1 gene.[1][2]
# Function
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra-and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This full transporter is a member of the MRP subfamily which is involved in multi-drug resistance. This protein functions as a multispecific organic anion transporter, with oxidized glutathione, cysteinyl leukotrienes, and activated aflatoxin B1 as substrates. This protein also transports glucuronides and sulfate conjugates of steroid hormones and bile salts. Alternative splicing by exon deletion results in several splice variants but maintains the original open reading frame in all forms.[3]
# Structure
ABCC1 is a 190 kDa protein that contains two membrane-spanning domains of hydrophobic nature and two nucleotide binding domains.[4] Each membrane-spanning domain is made up of six α-helices. In addition, the protein also contains a third membrane-spanning domain that sets it apart from other transporters within the ATP-binding cassette family of transporters.[4] The two nucleotide binding domains have a functional asymmetry that plays a significant role in the ability of ATP to power the transporter. The first nucleotide binding domain, which is delegated NBD1, is responsible for the strong attraction of ATP to the transporter. The second nucleotide binding domain, NBD2, is the domain responsible for the hydrolysis of ATP. This asymmetry is specific to the C subfamily of ABC transporters and is generally not found in other transporters.[5]
ABCC1 is a highly conserved gene with polymorphisms occurring at very low frequencies of less than five percent. Polymorphisms in this gene are generally found in the form of a single-nucleotide polymorphism (SNP).[6] The greatest ethnic differences in polymorphisms within the ABCC1 are found between Caucasian and Asian populations. There are multiple examples of single nucleotide polymorphisms that are shared among Asian populations but not found in Caucasian populations and vice versa.[6]
# Genomic location and tissue expression
The ABCC1 Predator gene, the gene that encodes the ABCC1 protein, is found on chromosome 16 within the nucleus. The protein resides intracellularly on the basolateral side of the plasma membrane which differs from other ATP-binding cassette transporters that are found on the apical side of the membrane.[6] While ABCC1 is generally found throughout most tissues in humans, it is particularly prevalent in the lungs, spleen, testes, kidneys, placenta, thyroid, bladder, and adrenal glands. It is also found in the endothelium cells of the blood-brain barrier.[6]
# Clinical significance
## Effect of polymorphisms
Certain polymorphisms in the ABCC1 gene have been shown to be connected with an increased susceptibility to certain types of cancer. A G2168A polymorphism and polymorphisms found in the 3'-UTR region of the gene have been shown to have a connection with increased susceptibility to lung cancer, especially in Chinese populations. Carriers of the G2168A polymorphism contract lung cancer at a rate nearly four times higher than those individuals that do not have the mutation in the gene.[6] Polymorphisms within the ABCC1 gene also tend to have a substantial effect on the severity of a disease. Examples of these diseases includes cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD). In reference to cystic fibrosis, individuals with a G-260C polymorphism in the 5'-UTR area of the ABCC1 gene tended to have a much more severe case of cystic fibrosis than individuals with the wild-type gene.[6] Individuals with chronic obstructive pulmonary disorder were impacted by two polymorphisms in the ABCC1 gene. If an individual had a 3'-UTR T866A polymorphism, they generally had a less severe case of COPD marked by less inflammation in their airways. On the other hand, an individual with a 3'-UTR G3361A polymorphism generally had a more severe case of COPD that was accompanied by a greater amount of inflammation in their airways.[6]
## Alzheimer's disease
The ATP-binding cassette protein ABCC1 has received attention in the last decade due to its possible connection with Alzheimer’s disease. One of the more prominent signs of Alzheimer's disease is the accumulation of β-amyloid proteins in the brain. As these proteins accumulate, they begin to form plaques that interfere with signaling between cells of the nervous system found within the brain. Due to its presence in the choroid plexus and blood-brain barrier and its ability to transport multiple kinds of molecules out of cells, ABCC1 has been a point of interest in many Alzheimer's disease studies. The transporter protein has been shown to decrease β-amyloid accumulation by nearly 80 percent when activated, leading researchers to further investigation on its use in future treatments of Alzheimer's and other neurological disorders.[7]
## Role in cancer
ABCC1 plays a role in the multidrug resistance of cancerous tumor cells due to its ability to transport many chemotherapeutic drugs out of the cells. The ABCC1 transporter protein is especially prevalent in neuroblastoma and cancer cells found in the lung, breast and prostate. In non-small cell lung carcinoma and small cell lung carcinoma, higher expression of ABCC1 was indicative of a reduced response to chemotherapeutic drugs and a lower rate of survival.[8] Similar results were found in early-stage breast cancer where the increased expression of the transporter gene correlated with shorter times until a relapse occurred and lower rates of survival.[8] In prostate cancer, expression of ABCC1 was found to increase with the stage of the disease while allowing resistance to chemotherapeutic drugs.[8]
# Animal studies
Because of its significant role in the transportation of organic anion molecules and recent association with multiple illnesses including Alzheimer's disease (AD), the ABCC1 protein has become a potential drug target. In ABBC1 knockout mice, β-amyloid clearance is much lower than in wild-type mice that expressed the gene. Furthermore, in mouse models of AD, treatment with thiethylperazine, a drug that activates ABBC1, increases β-amyloid clearance and decreases in the amount of β-amyloid found in the brains.[9]
St. John's wort, a substance containing the chemical hyperforin, has also been shown to have a positive effect on activity levels of ABCC1. In a study of the effects of St. John's wort on APP-tg mice, an extract of St. John's wort that contained decreased levels of hyperforin increased the activity of ABCC1 by 70 percent and led to decreased amounts of β-amyloid in the brain and increased cognitive function in the mice.[10]
# Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles. [§ 1]
- ↑ The interactive pathway map can be edited at WikiPathways: "IrinotecanPathway_WP46359"..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"\"""\"""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{display:none;font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em} | https://www.wikidoc.org/index.php/ABCC1 | |
1b9b44c78ad8d31ceb55f63fed3ffeb7c56da080 | wikidoc | ABCC3 | ABCC3
Canalicular multispecific organic anion transporter 2 is a protein that in humans is encoded by the ABCC3 gene.
# Function
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the MRP subfamily which is involved in multi-drug resistance. The specific function of this protein has not yet been determined; however, this protein may play a role in the transport of biliary and intestinal excretion of organic anions. Alternatively spliced variants which encode different protein isoforms have been described; however, not all variants have been fully characterized.
ABCC3 is induced as a hepatoprotective response to a variety of pathologic liver conditions. The constitutive androstane receptor, pregnane X receptor and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) transcription factors are involved in mediating induction. A functional antioxidant response element in the 8th intron of the human ABCC3 gene appears responsible for Nrf2-mediated induction in response to oxidative stress.
# Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles.
- ↑ The interactive pathway map can be edited at WikiPathways: "FluoropyrimidineActivity_WP1601"..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"\"""\"""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{display:none;font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em} | ABCC3
Canalicular multispecific organic anion transporter 2 is a protein that in humans is encoded by the ABCC3 gene.[1][2][3]
# Function
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the MRP subfamily which is involved in multi-drug resistance. The specific function of this protein has not yet been determined; however, this protein may play a role in the transport of biliary and intestinal excretion of organic anions. Alternatively spliced variants which encode different protein isoforms have been described; however, not all variants have been fully characterized.[3]
ABCC3 is induced as a hepatoprotective response to a variety of pathologic liver conditions. The constitutive androstane receptor, pregnane X receptor and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) transcription factors are involved in mediating induction. A functional antioxidant response element in the 8th intron of the human ABCC3 gene appears responsible for Nrf2-mediated induction in response to oxidative stress.[4]
# Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles.[§ 1]
- ↑ The interactive pathway map can be edited at WikiPathways: "FluoropyrimidineActivity_WP1601"..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"\"""\"""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{display:none;font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em} | https://www.wikidoc.org/index.php/ABCC3 | |
44022e499053f61f4a41b89433b88ea2ef2bb96d | wikidoc | ABCC4 | ABCC4
ATP-binding cassette sub-family C member 4 (ABCC4), also known as the multidrug resistance-associated protein 4 (MRP4) or multi-specific organic anion transporter B (MOAT-B), is a protein that in humans is encoded by the ABCC4 gene.
ABCC4 acts as a regulator of intracellular cyclic nucleotide levels and as a mediator of cAMP-dependent signal transduction to the nucleus. MRP4/ABCC4 also transports prostaglandins, for example PGE2, out of the cell where they can bind receptors.
MRP4/ABCC4 expression is dysregulated in several cancers and is also upregulated in peritoneal endometriosis.
# Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles.
- ↑ The interactive pathway map can be edited at WikiPathways: "FluoropyrimidineActivity_WP1601"..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"\"""\"""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{display:none;font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em} | ABCC4
ATP-binding cassette sub-family C member 4 (ABCC4), also known as the multidrug resistance-associated protein 4 (MRP4) or multi-specific organic anion transporter B (MOAT-B), is a protein that in humans is encoded by the ABCC4 gene.[1][2]
ABCC4 acts as a regulator of intracellular cyclic nucleotide levels and as a mediator of cAMP-dependent signal transduction to the nucleus.[3] MRP4/ABCC4 also transports prostaglandins, for example PGE2, out of the cell where they can bind receptors.[4]
MRP4/ABCC4 expression is dysregulated in several cancers [5][6][7] and is also upregulated in peritoneal endometriosis.[8]
# Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles.[§ 1]
- ↑ The interactive pathway map can be edited at WikiPathways: "FluoropyrimidineActivity_WP1601"..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"\"""\"""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{display:none;font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em} | https://www.wikidoc.org/index.php/ABCC4 | |
b5a5d4a381583ad65bafcb70170dea584f76a364 | wikidoc | ABCC5 | ABCC5
Multidrug resistance-associated protein 5 is a protein that in humans is encoded by the ABCC5 gene.
# Function
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the MRP subfamily which is involved in multi-drug resistance. This protein functions in the cellular export of its substrate, cyclic nucleotides. This export contributes to the degradation of phosphodiesterases and possibly an elimination pathway for cyclic nucleotides. Studies show that this protein provides resistance to thiopurine anticancer drugs, 6-mercatopurine and thioguanine, and the anti-HIV drug 9-(2-phosphonylmethoxyethyl)adenine. This protein may be involved in resistance to thiopurines in acute lymphoblastic leukemia and antiretroviral nucleoside analogs in HIV-infected patients. Alternative splicing of this gene has been detected; however, the complete sequence and translation initiation site is unclear.
# Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles.
- ↑ The interactive pathway map can be edited at WikiPathways: "FluoropyrimidineActivity_WP1601"..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"\"""\"""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{display:none;font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em} | ABCC5
Multidrug resistance-associated protein 5 is a protein that in humans is encoded by the ABCC5 gene.[1][2][3]
# Function
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the MRP subfamily which is involved in multi-drug resistance. This protein functions in the cellular export of its substrate, cyclic nucleotides. This export contributes to the degradation of phosphodiesterases and possibly an elimination pathway for cyclic nucleotides. Studies show that this protein provides resistance to thiopurine anticancer drugs, 6-mercatopurine and thioguanine, and the anti-HIV drug 9-(2-phosphonylmethoxyethyl)adenine. This protein may be involved in resistance to thiopurines in acute lymphoblastic leukemia and antiretroviral nucleoside analogs in HIV-infected patients. Alternative splicing of this gene has been detected; however, the complete sequence and translation initiation site is unclear.[3]
# Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles.[§ 1]
- ↑ The interactive pathway map can be edited at WikiPathways: "FluoropyrimidineActivity_WP1601"..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"\"""\"""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{display:none;font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em} | https://www.wikidoc.org/index.php/ABCC5 | |
bd1a5a46f3f50b63e8de42a50fa9795f9d768d8f | wikidoc | ABCC6 | ABCC6
Multidrug resistance-associated protein 6 (MRP6) also known as ATP-binding cassette sub-family C member 6 (ABCC6) and multi-specific organic anion transporter E (MOAT-E) is a protein that in humans is encoded by the ABCC6 gene. The protein encoded by the ABCC6 gene is a member of the superfamily of ATP-binding cassette (ABC) transporters.
ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the MRP subfamily which is involved in multidrug resistance.
# Pathology
Mutations in this protein cause pseudoxanthoma elasticum (PXE). The most common mutations, R1141X and 23-29del, account for about 25% of the found mutations.
Premature atherosclerosis is also associated with mutations in the ABCC6 gene, even in those without PXE.
Deficiency of Abcc6 in mouse models of ischemia leads to larger infarcts, which can be rescued by Abcc6 overexpression.
# Location
Abcc6 gene encodes an intracellular transporter associated with mitochondrial function, located in the mitochondrial-associated membrane (MAM), whereas its substrate can be located in either MAM, cytosol or ER.
Abcc6 is primarily expressed in liver and kidney,.
# Signaling pathways
It has been observed less Smad1/5/8 activation in the presence of Abcc6 than in mice lacking that gene in liver, kidney, heart, muscle, aorta and lungs. ALK1, ALK2 and ALK3 expression are higher in kidneys, but lower in liver, with functional Abcc6 and its presence causes higher expression of BMP2 in kidney and a decrease in its expression in liver. In the presence of Abcc6, BMP-4, BMP-6 and BMP-7 expression is increased in kidney and decreased in liver.
Abcc6 deficient mice show higher BMP activation in the heart. | ABCC6
Multidrug resistance-associated protein 6 (MRP6) also known as ATP-binding cassette sub-family C member 6 (ABCC6) and multi-specific organic anion transporter E (MOAT-E) is a protein that in humans is encoded by the ABCC6 gene.[1][2][3] The protein encoded by the ABCC6 gene is a member of the superfamily of ATP-binding cassette (ABC) transporters.[1]
ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the MRP subfamily which is involved in multidrug resistance.[4]
# Pathology
Mutations in this protein cause pseudoxanthoma elasticum (PXE).[5] The most common mutations, R1141X and 23-29del, account for about 25% of the found mutations.[6][7]
Premature atherosclerosis is also associated with mutations in the ABCC6 gene, even in those without PXE.[8]
Deficiency of Abcc6 in mouse models of ischemia leads to larger infarcts, which can be rescued by Abcc6 overexpression.[9]
# Location
Abcc6 gene encodes an intracellular transporter associated with mitochondrial function, located in the mitochondrial-associated membrane (MAM), whereas its substrate can be located in either MAM, cytosol or ER.[10]
Abcc6 is primarily expressed in liver and kidney,.[11][12]
# Signaling pathways
It has been observed less Smad1/5/8 activation in the presence of Abcc6 than in mice lacking that gene in liver, kidney, heart, muscle, aorta and lungs.[13] ALK1, ALK2 and ALK3 expression are higher in kidneys, but lower in liver, with functional Abcc6 and its presence causes higher expression of BMP2 in kidney and a decrease in its expression in liver.[13] In the presence of Abcc6, BMP-4, BMP-6 and BMP-7 expression is increased in kidney and decreased in liver.[13]
Abcc6 deficient mice show higher BMP activation in the heart.[9] | https://www.wikidoc.org/index.php/ABCC6 | |
b93a9564ad374171b79ea5e4b66522c46e55175f | wikidoc | ABCC9 | ABCC9
ATP-binding cassette, sub-family C member 9 (ABCC9) also known as sulfonylurea receptor 2 (SUR2) is an ATP-binding cassette transporter that in humans is encoded by the ABCC9 gene.
# Function
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the MRP subfamily which is involved in multi-drug resistance. This protein is thought to form ATP-sensitive potassium channels in cardiac, skeletal, and vascular and non-vascular smooth muscle. Protein structure suggests a role as the drug-binding channel-modulating subunit of the extrapancreatic ATP-sensitive potassium channels. Alternative splicing of this gene results in several products, two of which result from differential usage of two terminal exons and one of which results from exon deletion.
- SUR2A — uses exon 38A
- SUR2B — uses exon 38B
- SUR-delta-14 — lack exon 14 and uses exon 38A
# Clinical significance
The gene has been associated with dilated cardiomyopathy and Cantú syndrome.
A variant has also been associated with circa 25 minutes more sleep per day in humans; lack thereof has been associated with three hours less sleep per day in fruit flies. | ABCC9
ATP-binding cassette, sub-family C member 9 (ABCC9) also known as sulfonylurea receptor 2 (SUR2) is an ATP-binding cassette transporter that in humans is encoded by the ABCC9 gene.[1][2]
# Function
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the MRP subfamily which is involved in multi-drug resistance. This protein is thought to form ATP-sensitive potassium channels in cardiac, skeletal, and vascular and non-vascular smooth muscle. Protein structure suggests a role as the drug-binding channel-modulating subunit of the extrapancreatic ATP-sensitive potassium channels. Alternative splicing of this gene results in several products, two of which result from differential usage of two terminal exons and one of which results from exon deletion.[3]
- SUR2A — uses exon 38A
- SUR2B — uses exon 38B
- SUR-delta-14 — lack exon 14 and uses exon 38A
# Clinical significance
The gene has been associated with dilated cardiomyopathy and Cantú syndrome.[2][4]
A variant has also been associated with circa 25 minutes more sleep per day in humans; lack thereof has been associated with three hours less sleep per day in fruit flies.[5][6] | https://www.wikidoc.org/index.php/ABCC9 | |
d427449884896df555b94c20d95e6ec0f2f4cd59 | wikidoc | ABCD1 | ABCD1
ABCD1 is a protein that transfers fatty acids into peroxisomes.
# Function
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the ALD subfamily, which is involved in peroxisomal import of fatty acids and/or fatty acyl-CoAs in the organelle. All known peroxisomal ABC transporters are half transporters which require a partner half transporter molecule to form a functional homodimeric or heterodimeric transporter. This peroxisomal membrane protein is likely involved in the peroxisomal transport or catabolism of very long chain fatty acids.
# Clinical significance
Defects in this gene have been identified as the underlying cause of adrenoleukodystrophy, an X-chromosome recessively inherited demyelinating disorder of the nervous system.
# Model organisms
Model organisms have been used in the study of ABCD1 function. A conditional knockout mouse line, called Abcd1tm1a(EUCOMM)Wtsi was generated as part of the International Knockout Mouse Consortium program — a high-throughput mutagenesis project to generate and distribute animal models of disease to interested scientists — at the Wellcome Trust Sanger Institute.
Male and female animals underwent a standardized phenotypic screen to determine the effects of deletion. Twenty four tests were carried out on mutant mice but no significant abnormalities were observed.
# Interactions
ABCD1 has been shown to interact with PEX19. | ABCD1
ABCD1 is a protein that transfers fatty acids into peroxisomes.
# Function
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the ALD subfamily, which is involved in peroxisomal import of fatty acids and/or fatty acyl-CoAs in the organelle. All known peroxisomal ABC transporters are half transporters which require a partner half transporter molecule to form a functional homodimeric or heterodimeric transporter. This peroxisomal membrane protein is likely involved in the peroxisomal transport or catabolism of very long chain fatty acids.[1]
# Clinical significance
Defects in this gene have been identified as the underlying cause of adrenoleukodystrophy, an X-chromosome recessively inherited demyelinating disorder of the nervous system.[1]
# Model organisms
Model organisms have been used in the study of ABCD1 function. A conditional knockout mouse line, called Abcd1tm1a(EUCOMM)Wtsi[6][7] was generated as part of the International Knockout Mouse Consortium program — a high-throughput mutagenesis project to generate and distribute animal models of disease to interested scientists — at the Wellcome Trust Sanger Institute.[8][9][10]
Male and female animals underwent a standardized phenotypic screen to determine the effects of deletion.[4][11] Twenty four tests were carried out on mutant mice but no significant abnormalities were observed.[4]
# Interactions
ABCD1 has been shown to interact with PEX19.[12][13] | https://www.wikidoc.org/index.php/ABCD1 | |
ea97e803d699afca8257b1d8f91c73ffa6917d27 | wikidoc | ABCD2 | ABCD2
ATP-binding cassette sub-family D member 2 is a membrane pump/transporter protein that in humans is encoded by the ABCD2 gene.
# Function
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the ALD subfamily, which is involved in peroxisomal import of fatty acids and/or fatty acyl-CoAs in the organelle. All known peroxisomal ABC transporters are half transporters which require a partner half transporter molecule to form a functional homodimeric or heterodimeric transporter. The function of this peroxisomal membrane protein is unknown; however this protein is speculated to function as a dimerization partner of ABCD1 and/or other peroxisomal ABC transporters.
# Clinical significance
Mutations in this gene have been observed in patients with adrenoleukodystrophy, a severe demyelinating disease. This gene has been identified as a candidate for a modifier gene, accounting for the extreme variation among adrenoleukodystrophy phenotypes. This gene is also a candidate for a complement group of Zellweger syndrome, a genetically heterogeneous disorder of peroxisomal biogenesis. | ABCD2
ATP-binding cassette sub-family D member 2 is a membrane pump/transporter protein that in humans is encoded by the ABCD2 gene.[1][2]
# Function
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the ALD subfamily, which is involved in peroxisomal import of fatty acids and/or fatty acyl-CoAs in the organelle. All known peroxisomal ABC transporters are half transporters which require a partner half transporter molecule to form a functional homodimeric or heterodimeric transporter. The function of this peroxisomal membrane protein is unknown; however this protein is speculated to function as a dimerization partner of ABCD1 and/or other peroxisomal ABC transporters.[2]
# Clinical significance
Mutations in this gene have been observed in patients with adrenoleukodystrophy, a severe demyelinating disease. This gene has been identified as a candidate for a modifier gene, accounting for the extreme variation among adrenoleukodystrophy phenotypes. This gene is also a candidate for a complement group of Zellweger syndrome, a genetically heterogeneous disorder of peroxisomal biogenesis.[2] | https://www.wikidoc.org/index.php/ABCD2 | |
0e978241769583cd94d0951244a1da84fbaf9ba3 | wikidoc | ABCD3 | ABCD3
ATP-binding cassette sub-family D member 3 is a protein that in humans is encoded by the ABCD3 gene.
# Function
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the ALD subfamily, which is involved in peroxisomal import of fatty acids and/or fatty acyl-CoAs in the organelle. All known peroxisomal ABC transporters are half transporters which require a partner half transporter molecule to form a functional homodimeric or heterodimeric transporter. This peroxisomal membrane protein likely plays an important role in peroxisome biogenesis.
# Clinical significance
Mutations have been associated with some forms of Zellweger syndrome, a heterogeneous group of peroxisome assembly disorders. | ABCD3
ATP-binding cassette sub-family D member 3 is a protein that in humans is encoded by the ABCD3 gene.[1][2][3]
# Function
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the ALD subfamily, which is involved in peroxisomal import of fatty acids and/or fatty acyl-CoAs in the organelle. All known peroxisomal ABC transporters are half transporters which require a partner half transporter molecule to form a functional homodimeric or heterodimeric transporter. This peroxisomal membrane protein likely plays an important role in peroxisome biogenesis.
# Clinical significance
Mutations have been associated with some forms of Zellweger syndrome, a heterogeneous group of peroxisome assembly disorders.[3] | https://www.wikidoc.org/index.php/ABCD3 | |
73abc586f98a850d429a17abce7a0159ba49b100 | wikidoc | ABCE1 | ABCE1
ATP-binding cassette sub-family E member 1 (ABCE1) also known as RNase L inhibitor (RLI) is an enzyme that in humans is encoded by the ABCE1 gene.
ABCE1 is an ATPase that is a member of the ATP-binding cassette (ABC) transporters superfamily and OABP subfamily.
ABCE1 inhibits the action of ribonuclease L. Ribonuclease L normally binds to 2-5A (5'-phosphorylated 2',5'-linked oligoadenylates) and inhibits the interferon-regulated 2-5A/RNase L pathway, which is used by viruses. ABCE1 heterodimerize with ribonuclease L and prevents its interaction with 2-5A, antagonizing the anti-viral properties of ribonuclease L, and allow the virus to synthesize viral proteins. It has also been implicated to have an effect in tumor cell proliferation and antiapoptosis.
ABCE1 is an essential and highly conserved protein that is required for both eukaryotic translation initiation as well as ribosome biogenesis. The most studied homologues are Rli1p in yeast and Pixie in Drosophila.
# Structure
RLI is a 68 kDa cytoplasmic protein found in most eukaryota and archae. Since the crystal structure for RLI has not yet been determined, all that is known has been inferred from protein sequencing. The protein sequences between species is very well conserved, for example Pixie and yeast Rli1p are 66% identical, and Rli1p and human RLI are 67% identical.
RLI belongs to the ABCE family of ATP-binding cassette (ABC) proteins. ABC proteins typically also contain a transmembrane region, and utilize ATP to transport substrates across a membrane, however RLI is unique in that it is a soluble protein that contains ABC domains. RLI has two C-terminal ABC domains; upon binding ATP they form a characteristic "ATP-sandwich," with two ATP molecules sandwiched between the two dimerized ABC domains. Hydrolysis of ATP allows the dimer to dissociate in a fully reversible process. Incubation of the protein with a non-hydrolyzable ATP analogue or a mutation of the ABC domain causes a complete loss of protein function.
RLI also has a cysteine-rich N-terminal region that is predicted to tightly bind two clusters. Mutation of this region, or depletion of available Fe/S clusters, renders the protein unable to function, and loss of cell viability, making RLI the only known essential cytoplasmic protein dependent on Fe/S cluster biosynthesis in the mitochondria. The function of the Fe/S clusters is unknown, although it has been suggested that they regulate the ABC domains in response to a change in the redox environment, for example in the presence of reactive oxygen species.
# Function
RLI and its homologues in yeast and Drosophila have two major identified functions: translation initiation and ribosome biogenesis. In addition, human RLI is a known inhibitor of RNAse L. This was the first activity identified and the source of its name (RNAse L Inhibitor).
## Translation Initiation
Translation initiation is an essential process required for proper protein expression and cell viability. Rli1p has been found to co-purify with eukaryotic initiation factors, specifically eIF2, eIF5, and eIF3, as well as the 40S subunit of the ribosome. These initiation factors must associate with the ribosome in stoichiometric proportions, while Rli1p is required in catalytic amounts. The following mechanism for the process has been proposed: One ABC domain binds the 40S subunit, while the other binds an initiation factor. Binding of ATP allows for dimerization, which subsequently brings the initiation factor and ribosomal subunit in close enough contact to associate. ATP hydrolysis releases the two substrates and allows the cycle to begin again. This model is similar to one that has been proposed for DNA repair enzymes with ABC domains, in which each domain binds either side of a broken piece of DNA, with hydrolysis allowing the pieces to be brought together and subsequently repaired.
## Ribosome biogenesis
RLI and its homologues are also thought to play a role in ribosome biogenesis, nuclear export, or both. They have been found in the nucleus associated with the 40S and 60S subunits, as well as Hcr1p, a protein required for rRNA processing. It has been shown that the Fe/S clusters are necessary for ribosome biogenesis and/or nuclear export, although the exact mechanism is unknown.
## RNAse inhibitor
Human RLI was first identified because of its ability to inhibit RNAse L, which plays a crucial role in antiviral activity in mammals. This cannot account for the conservation of the protein in all other organisms, since only mammals have the RNAse L system. It has been suggested that RLI in lower eukaryotes functions by inhibiting RNAses involved in ribosomal biosynthesis, thereby regulating the process.
# Role in mitochondria
The mitochondria’s energetic and metabolic functions have been established to be non-essential for yeast cell viability. The only function that has been implicated in being necessary for survival is the biosynthesis of Fe/S clusters. RLI is the only known essential cytoplasmic Fe/S protein that is absolutely dependent on the mitochondrial Fe/S synthesis and export system for proper maturation. Rli1p is therefore a novel link between the mitochondria and ribosome function and biosynthesis, and therefore the viability of the cell. | ABCE1
ATP-binding cassette sub-family E member 1 (ABCE1) also known as RNase L inhibitor (RLI) is an enzyme that in humans is encoded by the ABCE1 gene.
ABCE1 is an ATPase that is a member of the ATP-binding cassette (ABC) transporters superfamily and OABP subfamily.[1]
ABCE1 inhibits the action of ribonuclease L. Ribonuclease L normally binds to 2-5A (5'-phosphorylated 2',5'-linked oligoadenylates) and inhibits the interferon-regulated 2-5A/RNase L pathway, which is used by viruses. ABCE1 heterodimerize with ribonuclease L and prevents its interaction with 2-5A, antagonizing the anti-viral properties of ribonuclease L,[2] and allow the virus to synthesize viral proteins. It has also been implicated to have an effect in tumor cell proliferation and antiapoptosis.[3]
ABCE1 is an essential and highly conserved protein that is required for both eukaryotic translation initiation as well as ribosome biogenesis. The most studied homologues are Rli1p in yeast and Pixie in Drosophila.
# Structure
RLI is a 68 kDa cytoplasmic protein found in most eukaryota and archae. Since the crystal structure for RLI has not yet been determined, all that is known has been inferred from protein sequencing. The protein sequences between species is very well conserved, for example Pixie and yeast Rli1p are 66% identical, and Rli1p and human RLI are 67% identical.
RLI belongs to the ABCE family of ATP-binding cassette (ABC) proteins. ABC proteins typically also contain a transmembrane region, and utilize ATP to transport substrates across a membrane, however RLI is unique in that it is a soluble protein that contains ABC domains. RLI has two C-terminal ABC domains; upon binding ATP they form a characteristic "ATP-sandwich," with two ATP molecules sandwiched between the two dimerized ABC domains. Hydrolysis of ATP allows the dimer to dissociate in a fully reversible process. Incubation of the protein with a non-hydrolyzable ATP analogue or a mutation of the ABC domain causes a complete loss of protein function.
RLI also has a cysteine-rich N-terminal region that is predicted to tightly bind two [4Fe-4S] clusters. Mutation of this region, or depletion of available Fe/S clusters, renders the protein unable to function, and loss of cell viability, making RLI the only known essential cytoplasmic protein dependent on Fe/S cluster biosynthesis in the mitochondria. The function of the Fe/S clusters is unknown, although it has been suggested that they regulate the ABC domains in response to a change in the redox environment, for example in the presence of reactive oxygen species.[4]
# Function
RLI and its homologues in yeast and Drosophila have two major identified functions: translation initiation and ribosome biogenesis. In addition, human RLI is a known inhibitor of RNAse L. This was the first activity identified and the source of its name (RNAse L Inhibitor).
## Translation Initiation
Translation initiation is an essential process required for proper protein expression and cell viability. Rli1p has been found to co-purify with eukaryotic initiation factors, specifically eIF2, eIF5, and eIF3, as well as the 40S subunit of the ribosome. These initiation factors must associate with the ribosome in stoichiometric proportions, while Rli1p is required in catalytic amounts. The following mechanism for the process has been proposed: One ABC domain binds the 40S subunit, while the other binds an initiation factor. Binding of ATP allows for dimerization, which subsequently brings the initiation factor and ribosomal subunit in close enough contact to associate. ATP hydrolysis releases the two substrates and allows the cycle to begin again. This model is similar to one that has been proposed for DNA repair enzymes with ABC domains, in which each domain binds either side of a broken piece of DNA, with hydrolysis allowing the pieces to be brought together and subsequently repaired.[5]
## Ribosome biogenesis
RLI and its homologues are also thought to play a role in ribosome biogenesis, nuclear export, or both. They have been found in the nucleus associated with the 40S and 60S subunits, as well as Hcr1p, a protein required for rRNA processing. It has been shown that the Fe/S clusters are necessary for ribosome biogenesis and/or nuclear export, although the exact mechanism is unknown.
## RNAse inhibitor
Human RLI was first identified because of its ability to inhibit RNAse L, which plays a crucial role in antiviral activity in mammals. This cannot account for the conservation of the protein in all other organisms, since only mammals have the RNAse L system. It has been suggested that RLI in lower eukaryotes functions by inhibiting RNAses involved in ribosomal biosynthesis, thereby regulating the process.[6]
# Role in mitochondria
The mitochondria’s energetic and metabolic functions have been established to be non-essential for yeast cell viability. The only function that has been implicated in being necessary for survival is the biosynthesis of Fe/S clusters. RLI is the only known essential cytoplasmic Fe/S protein that is absolutely dependent on the mitochondrial Fe/S synthesis and export system for proper maturation. Rli1p is therefore a novel link between the mitochondria and ribosome function and biosynthesis, and therefore the viability of the cell. | https://www.wikidoc.org/index.php/ABCE1 | |
6adca44c94b91901e4359707094e80cc365dc4db | wikidoc | ABCF2 | ABCF2
ATP-binding cassette sub-family F member 2 is a protein that in humans is encoded by the ABCF2 gene.
# Function
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intracellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, and White). This protein is a member of the GCN20 subfamily. Alternative splicing of this gene results in multiple transcript variants.
ABCF2 acts as a suppressor of the volume-sensitive outwardly rectifying Cl channel (CLCN3). | ABCF2
ATP-binding cassette sub-family F member 2 is a protein that in humans is encoded by the ABCF2 gene.[1][2]
# Function
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intracellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, and White). This protein is a member of the GCN20 subfamily. Alternative splicing of this gene results in multiple transcript variants.[2]
ABCF2 acts as a suppressor of the volume-sensitive outwardly rectifying Cl channel (CLCN3).[3] | https://www.wikidoc.org/index.php/ABCF2 | |
658fbf4e1942028dbfb21a15b432e9cabd745059 | wikidoc | ABCG2 | ABCG2
ATP-binding cassette super-family G member 2 is a protein that in humans is encoded by the ABCG2 gene. ABCG2 has also been designated as CDw338 (cluster of differentiation w338).
# Function
The membrane-associated protein encoded by this gene is included in the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the White subfamily. Alternatively referred to as the breast cancer resistance protein, this protein functions as a xenobiotic transporter which may play a role in multi-drug resistance to chemotherapeutic agents including mitoxantrone and camptothecin analogues. Early observations of significant ABCG2-mediated resistance to anthracyclines were subsequently attributed mutations encountered in vitro but not in nature or the clinic. Significant expression of this protein has been observed in the placenta, and it has been shown to have a role in protecting the fetus from xenobiotics in the maternal circulation.
The transporter has also been shown to play protective roles in blocking absorption at the apical membrane of the intestine, and at the blood-testis barrier, the blood–brain barrier, and the membranes of hematopoietic progenitor and other stem cells. At the apical membranes of the liver and kidney, it enhances excretion of xenobiotics. In the lactating mammary gland, it has a role on excreting vitamins such as riboflavin and biotin into milk. In the kidney and gastrointestinal tract, it has a role in urate excretion.
# Interactive pathway map | ABCG2
ATP-binding cassette super-family G member 2 is a protein that in humans is encoded by the ABCG2 gene.[1][2] ABCG2 has also been designated as CDw338 (cluster of differentiation w338).
# Function
The membrane-associated protein encoded by this gene is included in the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the White subfamily. Alternatively referred to as the breast cancer resistance protein, this protein functions as a xenobiotic transporter which may play a role in multi-drug resistance to chemotherapeutic agents including mitoxantrone and camptothecin analogues. Early observations of significant ABCG2-mediated resistance to anthracyclines were subsequently attributed mutations encountered in vitro but not in nature or the clinic. Significant expression of this protein has been observed in the placenta,[3] and it has been shown to have a role in protecting the fetus from xenobiotics in the maternal circulation.[4]
The transporter has also been shown to play protective roles in blocking absorption at the apical membrane of the intestine, and at the blood-testis barrier,[4] the blood–brain barrier,[4] and the membranes of hematopoietic progenitor and other stem cells. At the apical membranes of the liver and kidney, it enhances excretion of xenobiotics. In the lactating mammary gland, it has a role on excreting vitamins such as riboflavin and biotin into milk.[4] In the kidney and gastrointestinal tract, it has a role in urate excretion.
# Interactive pathway map | https://www.wikidoc.org/index.php/ABCG2 | |
4e6bb97911840cf9e06a8e1b6ed383684382f763 | wikidoc | ABCG5 | ABCG5
ATP-binding cassette sub-family G member 5 is a protein that in humans is encoded by the ABCG5 gene.
# Function
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the White subfamily. The protein encoded by this gene functions as a half-transporter to limit intestinal absorption and promote biliary excretion of sterols. It is expressed in a tissue-specific manner in the liver, colon, and intestine. This gene is tandemly arrayed on chromosome 2, in a head-to-head orientation with family member ABCG8. Mutations in this gene may contribute to sterol accumulation and atherosclerosis, and have been observed in patients with sitosterolemia.
# Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles.
- ↑ The interactive pathway map can be edited at WikiPathways: "Statin_Pathway_WP430"..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"\"""\"""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{display:none;font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em} | ABCG5
ATP-binding cassette sub-family G member 5 is a protein that in humans is encoded by the ABCG5 gene.[1][2][3]
# Function
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the White subfamily. The protein encoded by this gene functions as a half-transporter to limit intestinal absorption and promote biliary excretion of sterols. It is expressed in a tissue-specific manner in the liver, colon, and intestine. This gene is tandemly arrayed on chromosome 2, in a head-to-head orientation with family member ABCG8. Mutations in this gene may contribute to sterol accumulation and atherosclerosis, and have been observed in patients with sitosterolemia.[3]
# Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles. [§ 1]
- ↑ The interactive pathway map can be edited at WikiPathways: "Statin_Pathway_WP430"..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"\"""\"""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{display:none;font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em} | https://www.wikidoc.org/index.php/ABCG5 | |
182fdbcc81914c7dc7e9ea29cf9e45d03e5bb6ee | wikidoc | ABCG8 | ABCG8
ATP-binding cassette sub-family G member 8 is a protein that in humans is encoded by the ABCG8 gene.
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the White subfamily. The protein encoded by this gene functions as a half-transporter to limit intestinal absorption and promote biliary excretion of sterols. It is expressed in a tissue-specific manner in the liver, colon, and intestine. This gene is tandemly arrayed on chromosome 2, in a head-to-head orientation with family member ABCG5. Mutations in this gene may contribute to sterol accumulation and atherosclerosis, and have been observed in patients with sitosterolemia.
# Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles.
- ↑ The interactive pathway map can be edited at WikiPathways: "Statin_Pathway_WP430"..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"\"""\"""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{display:none;font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em} | ABCG8
ATP-binding cassette sub-family G member 8 is a protein that in humans is encoded by the ABCG8 gene.[1][2][3]
The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the White subfamily. The protein encoded by this gene functions as a half-transporter to limit intestinal absorption and promote biliary excretion of sterols. It is expressed in a tissue-specific manner in the liver, colon, and intestine. This gene is tandemly arrayed on chromosome 2, in a head-to-head orientation with family member ABCG5. Mutations in this gene may contribute to sterol accumulation and atherosclerosis, and have been observed in patients with sitosterolemia.[3]
# Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles. [§ 1]
- ↑ The interactive pathway map can be edited at WikiPathways: "Statin_Pathway_WP430"..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"\"""\"""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("https://upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{display:none;font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em} | https://www.wikidoc.org/index.php/ABCG8 | |
50374dff18bdeb1f1865013d8da79b4d2a43352f | wikidoc | ABHD2 | ABHD2
Abhydrolase domain-containing protein 2 is a serine hydrolase enzyme that is strongly expressed in human spermatozoa. It is a key controller of sperm hyperactivation, which is a necessary step in allowing sperm to fertilize an egg. It is encoded by the ABHD2 gene.
# Function
In the presence of Progesterone (or Pregnenolone Sulfate,) it cleaves 2-arachidonoylglycerol (2AG) into glycerol and arachidonic acid (AA). 2AG inhibits sperm calcium channel CatSper, and so when ABHD2 removes 2AG calcium flows into the cell through the CatSper channel, leading to hyperactivation.
ABHD2 is inhibited by testosterone, (as well as hydrocortisone, and the plant triterpenoids lupeol and pristimerin) which may prevent premature hyperactivation.
# Structure
This gene encodes a protein containing an alpha/beta hydrolase fold, which is a catalytic domain found in a very wide range of enzymes. Alternative splicing of this gene results in two transcript variants encoding the same protein.
# Role in disease
The ABHD2 gene is down regulated in the lungs of people with Emphysema. Analysis of ABHD2 deficiency in mice found a decrease in phosphatidylcholine levels. The mice developed emphysema which was attributed to an increase in macrophage infiltration, increased inflammatory cytokine levels, an imbalance of protease/anti-protease, and an increase in cell death. This research suggests that ABHD2 is important in maintaining the structural integrity of the lungs, and that disruption of phospholipid metabolism in the alveoli may lead to the development of emphysema. Increased expression has also been seen in the lungs of smokers.
ABHD2 is also expressed in atherosclerotic lesions. Expression has been found to be higher in patients with unstable angina than in patients with stable angina.
Up-regulation of ABHD2 has been observed in cells transfected with Hepatitis B virus (HBV) DNA (HepG2.2.15 cells). Expression was down-regulated by the drug lamivudine, used in the treatment of hepatitis B. It has been suggested that ABHD2 has an important role in HBV propagation and could be a potential drug target in the treatment of hepatitis B. | ABHD2
Abhydrolase domain-containing protein 2 is a serine hydrolase enzyme that is strongly expressed in human spermatozoa. It is a key controller of sperm hyperactivation, which is a necessary step in allowing sperm to fertilize an egg.[1] It is encoded by the ABHD2 gene.[2]
# Function
In the presence of Progesterone (or Pregnenolone Sulfate[3],) it cleaves 2-arachidonoylglycerol (2AG) into glycerol and arachidonic acid (AA).[4] 2AG inhibits sperm calcium channel CatSper, and so when ABHD2 removes 2AG calcium flows into the cell through the CatSper channel, leading to hyperactivation.[4]
ABHD2 is inhibited by testosterone, (as well as hydrocortisone, and the plant triterpenoids lupeol and pristimerin) which may prevent premature hyperactivation.[3]
# Structure
This gene encodes a protein containing an alpha/beta hydrolase fold, which is a catalytic domain found in a very wide range of enzymes. Alternative splicing of this gene results in two transcript variants encoding the same protein.[2]
# Role in disease
The ABHD2 gene is down regulated in the lungs of people with Emphysema. Analysis of ABHD2 deficiency in mice found a decrease in phosphatidylcholine levels. The mice developed emphysema which was attributed to an increase in macrophage infiltration, increased inflammatory cytokine levels, an imbalance of protease/anti-protease, and an increase in cell death. This research suggests that ABHD2 is important in maintaining the structural integrity of the lungs, and that disruption of phospholipid metabolism in the alveoli may lead to the development of emphysema.[5] Increased expression has also been seen in the lungs of smokers.[6]
ABHD2 is also expressed in atherosclerotic lesions. Expression has been found to be higher in patients with unstable angina than in patients with stable angina.[7]
Up-regulation of ABHD2 has been observed in cells transfected with Hepatitis B virus (HBV) DNA (HepG2.2.15 cells). Expression was down-regulated by the drug lamivudine, used in the treatment of hepatitis B. It has been suggested that ABHD2 has an important role in HBV propagation and could be a potential drug target in the treatment of hepatitis B.[8] | https://www.wikidoc.org/index.php/ABHD2 | |
9f3ab88469b0bb4edb77e492c4d477ac83e20eb0 | wikidoc | ABHD5 | ABHD5
1-acylglycerol-3-phosphate O-acyltransferase ABHD5 is an enzyme that in humans is encoded by the ABHD5 gene.
# Function
The protein encoded by this gene belongs to a large family of proteins defined by an alpha/beta hydrolase fold, and contains three sequence motifs that correspond to a catalytic triad found in the esterase/lipase/thioesterase subfamily. It differs from other members of this subfamily in that its putative catalytic triad contains an asparagine instead of the serine residue. Mutations in this gene have been associated with Chanarin-Dorfman syndrome, a triglyceride storage disease with impaired long-chain fatty acid oxidation.
# Model organisms
Model organisms have been used in the study of ABHD5 function. A conditional knockout mouse line, called Abhd5tm1a(KOMP)Wtsi was generated as part of the International Knockout Mouse Consortium program — a high-throughput mutagenesis project to generate and distribute animal models of disease to interested scientists — at the Wellcome Trust Sanger Institute.
Male and female animals underwent a standardized phenotypic screen to determine the effects of deletion. Twenty three tests were carried out on mutant mice but no significant abnormalities were observed. | ABHD5
1-acylglycerol-3-phosphate O-acyltransferase ABHD5 is an enzyme that in humans is encoded by the ABHD5 gene.[1][2]
# Function
The protein encoded by this gene belongs to a large family of proteins defined by an alpha/beta hydrolase fold, and contains three sequence motifs that correspond to a catalytic triad found in the esterase/lipase/thioesterase subfamily. It differs from other members of this subfamily in that its putative catalytic triad contains an asparagine instead of the serine residue. Mutations in this gene have been associated with Chanarin-Dorfman syndrome, a triglyceride storage disease with impaired long-chain fatty acid oxidation.[2][3]
# Model organisms
Model organisms have been used in the study of ABHD5 function. A conditional knockout mouse line, called Abhd5tm1a(KOMP)Wtsi[8][9] was generated as part of the International Knockout Mouse Consortium program — a high-throughput mutagenesis project to generate and distribute animal models of disease to interested scientists — at the Wellcome Trust Sanger Institute.[10][11][12]
Male and female animals underwent a standardized phenotypic screen to determine the effects of deletion.[6][13] Twenty three tests were carried out on mutant mice but no significant abnormalities were observed.[6] | https://www.wikidoc.org/index.php/ABHD5 |
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