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11099073 | Risks of acquiring and transmitting sexually transmitted diseases in sexual partner networks. | A person's risk for acquiring infection and their role in continued transmission has traditionally been assessed on the basis of individual characteristics. Recently, network studies have attempted to relate individual risks to position in the wider network. |
11099075 | More realistic models of sexually transmitted disease transmission dynamics: sexual partnership networks, pair models, and moment closure. | Mathematical models of sexually transmitted disease transmission have proven powerful tools for interpreting observed epidemiologic pattern. However, the monly used formulation of such models largely fail to capture the effect of partnership concurrency and contact network structure on transmission. |
11099076 | Remarks on the role of economic modeling. | Despite the growing scholarly acceptance of quantitative evaluation methods, modelers still struggle to define an appropriate role for their work at the decision-making level. |
11099077 | Modeling contact networks and infection transmission in geographic and social space using GERMS. | Stochastic models of discrete individuals and deterministic models of continuous populations may give different answers to questions about infectious diseases. |
11099078 | Sexual network structure and sexually transmitted disease prevention: a modeling perspective. | Mathematical modeling techniques are being used increasingly to plan public health policy for the prevention of sexually transmitted diseases. |
11099079 | Mathematical models of the transmission and control of sexually transmitted diseases. | The development of mathematical models to describe and interpret the epidemiology of sexually transmitted infections has involved the incremental addition of various forms of biological and plexity to simple mathematical templates. |
11099082 | Viral strain identification in varicella vaccinees with disseminated rashes. | Approximately 15% of recipients of live attenuated varicella vaccine may develop mild breakthrough varicella months to years after immunization. Although some vaccinees will develop zoster, it is mon in recipients of vaccine than in those who have had natural varicella. |
11099083 | Bacteriologic and clinical efficacy of one day vs. three day intramuscular ceftriaxone for treatment of nonresponsive acute otitis media in children. | One dose of intramuscular ceftriaxone has been recently licensed in the United States for the treatment of acute otitis media. However, data regarding the bacteriologic and clinical efficacy of this regimen in the treatment of nonresponsive acute otitis media are plete. |
11099084 | Immunization against hepatitis A in the first year of life: priming despite the presence of maternal antibody. | Maternal antibodies interfere with hepatitis A vaccination in young infants. We examined the response to a high dose hepatitis A vaccine administered itantly with bination of diphtheria-tetanus toxoids-acellular pertussis-inactivated poliovirus vaccine/Haemophilus influenzae type b vaccine to initially seropositive vs. initially seronegative infants. |
11099085 | The Immunization Monitoring Program Active (IMPACT) prospective five year study of Canadian children hospitalized for chickenpox or an associated complication. | Varicella vaccine was approved for use in Canada in 1998. A major goal of universal varicella vaccine programs is to reduce severe infection and plications. Baseline data are essential against which to judge the effectiveness of routine childhood immunization. |
11099086 | Oral ciprofloxacin vs. intramuscular ceftriaxone as empiric treatment of acute invasive diarrhea in children. | Acute invasive diarrhea is a potentially serious condition in children. Because of the increasing resistance of enteric pathogens monly used oral antibiotics, intramuscular ceftriaxone has e the routine drug in the treatment of acute invasive diarrhea requiring an emergency visit in southern Israel. The inconvenience of this parenteral regimen created an increased need for oral pediatric formulations for the treatment of invasive diarrhea. |
11099087 | Effectiveness of palivizumab: evaluation of outcomes from the 1998 to 1999 respiratory syncytial virus season. The Palivizumab Outcomes Study Group. | Respiratory syncytial virus (RSV) remains a significant cause of morbidity, especially in premature infants and promised children, resulting in approximately 100 000 hospitalizations annually. A study was performed to evaluate the es of those given palivizumab (Synagis; MedImmune, Inc., Gaithersburg, MD) during the 1998 to 1999 RSV season, its first season in general use. |
11099089 | Mother-to-infant transmission of TT virus: prevalence, extent and mechanism of vertical transmission. | It is currently unknown which mechanisms are responsible for TT virus (TTV) infection in early childhood and whether it may be transmitted in utero from mother to infant. |
11099088 | Clinical sinusitis in children attending primary care centers. | To determine the proportion of children who meet the clinical criteria for the diagnosis of sinusitis among all children attending primary care pediatric practices, to explore the relationship between passive smoking and the occurrence of sinusitis and to study the role of antibiotics in the management of sinusitis. |
11099090 | Bacteriology of histopathologically defined appendicitis in children. | Acute appendicitis is the mon surgical emergency in childhood. However, the pathogenesis and detailed microbiology are obscure. |
11099091 | Pilot study of hydroxyurea in human immunodeficiency virus-infected children receiving didanosine and/or stavudine. | To evaluate the safety and antiviral and immunologic effects of hydroxyurea given with didanosine (ddI) and/or stavudine (d4T) to symptomatic HIV-infected children. |
11099092 | Relationship of climate, ethnicity and socioeconomic status to Kawasaki disease in San Diego County, 1994 through 1998. | Kawasaki disease (KD) is the mon cause of acquired heart disease in children in the United States. By monitoring trends in patient numbers and demographics during a 5-year period, we were able to explore the relationship between climate, ethnicity, socioeconomic status and susceptibility to KD. |
11099107 | Modulation of endothelin-1 in normal human keratinocytes by UVA1/B radiations, prostaglandin E2 and peptidase inhibitors. | In the skin, keratinocytes synthesize and secrete endothelin-(ET-1), a potent vasoconstrictor peptide which acts also as a growth factor for most skin cells. The aim of the study was to test the effects of UVA1 and the associations UVA1/B on the expression of ET-1 in normal human keratinocytes and to determine whether exogenously added prostaglandin E2 (PGE2) regulated ET-1 expression. As ET-1 is susceptible to degradation, we also evaluated whether ET-1 secretion was modulated by peptidase inhibitors. Our results showed that UVA1 (365 nm) did not modify the levels of preproET-1 mRNA and protein. Moreover, the associations UVA1+UVB or UVB+UVA1 down-regulated the overexpression of secreted ET-1 induced by UVB alone. PGE2 at 10(-5) M reduced the expression of ET-1 at the mRNA and protein levels but did not exert any significant modification at lower concentrations from 10(-10) to 10(6) M. Phosphoramidon, an endothelin converting enzyme (ECE) inhibitor, drastically decreased the amount of ET-1 accumulating in the culture medium in basal conditions or after UVB irradiation. Conversely, thiorphan, a specific inhibitor of neutral endopeptidase (NEP), rather increased the levels of ET-1 secretion mainly after UVB irradiation. Taken together, the results showed that normal human keratinocytes secrete and partly degrade ET-1 through ECE and NEP pathways and pointed out a differential regulation of ET-1 by UVB and UVA1 radiations without any noticeable role for PGE2. |
11099108 | Zinc, copper and manganese enhanced keratinocyte migration through a functional modulation of keratinocyte integrins. | The migration of keratinocytes plays an important role in the re-epithelialization of cutaneous wounds. Zinc, copper and manganese are used in vivo for their healing properties and their mechanism of action is still only partially known. Thus, they have been shown both to promote keratinocyte proliferation and to modulate integrins expression. The aim of this study was to determine if trace elements induce an increase of the migration of keratinocytes and if this effect is related to the modulation of integrins. Two independent migration assays were used to study keratinocyte migration: the scratch assay using normal human keratinocytes and the modified Boyden chamber using HaCaT cells. Inhibition studies using function-blocking antibodies directed to alpha3, alpha6, alpha(v) and beta1 subunits were performed to investigate the modulator effect of trace elements on integrin function. In this way, zinc and copper gluconates increased alpha3, alpha(v) and beta1 function whereas manganese gluconate seems mainly able to modulate the function of alpha3 and beta1. The stimulating effect of these trace elements on keratinocyte migration does not appear related to alpha6 subunit. Thus, zinc, copper and manganese enhanced keratinocyte migration and one of the mechanisms was going through a modulation of integrin functions. |
11099110 | Inhibition of intercellular adhesio nmolecule-1 (ICAM-1) expression in ultraviolet B-irradiated human antigen-presenting cells is restored after repair of cyclobutane pyrimidine dimers. | The present study assessed the molecular mechanism underlying ultraviolet (UV) B radiation-induced inhibition of the expression of the adhesion molecule ICAM-1 in human antigen-presenting cells (APC). UVB radiation-induced inhibition of ICAM-I expression in human peripheral blood monocytes was associated with the generation of cyclobutane pyrimidine dimers (CPD). CPD were reduced by 60% after treatment with liposomal packed photolyase, an enzyme which removes CPD after absorption of photoreactivating light. Although plete, reduction of CPD was associated plete restoration of ICAM-1 expression at the mRNA and protein level. Neither reduction of CPD level nor restoration of ICAM-1 expression were observed, if monocytes were treated with empty liposomes, or if they were irradiated with photoreactivating light prior to application of photolyase. DNA damage might also induce soluble mediators capable of autocrine inhibition of ICAM-1 expression. UVB irradiation of monocytes did not induce IL-10 production, but resulted in release of prostaglandin (PG) E2. Treatment of unirradiated monocytes with pletely inhibited ICAM-1 expression, thus mimicking the UVB effect. Inhibition of monocytic PGE2 production by indomethacin, however, did not restore ICAM-1 expression. These results suggest that formation of CPD is necessary and sufficient for UVB radiation-induced inhibition of ICAM-1 expression. In contrast, PGE2 might serve a paracrine role in UVB radiation-induced immunosuppression. |
11099109 | The effect of ultraviolet B irradiation on nitric oxide synthase expression in murine keratinocytes. | Nitric oxide (NO), which has several physiological functions in skin, is generated by NO synthase (NOS). NOS has at least three isoforms; endothelial NOS (eNOS), brain NOS (bNOS), and inducible NOS (iNOS). Ultraviolet B (UVB) irradiation has been reported to stimulate NO production in skin via induction or activation of NOS, however, the exact mechanism of NOS induction by UVB irradiation remains obscure. In this study, we investigated the direct effect of UVB on the expression of NOS isoforms in murine keratinocytes, and found a significant increase in NO production within 48 h. mRNA and protein expressions of bNOS were both enhanced by UVB irradiation in murine keratinocytes, whereas iNOS mRNA expression was suppressed at 4 and 12 h after UVB irradiation. These results suggest that the enhancement of NO production observed after UVB irradiation in murine keratinocytes may be explained in part by the upregulation of bNOS expression, but not iNOS expression. |
11099112 | What is the most promising strategy for the treatment of metastasizing melanoma? | The treatment of patients with metastasizing melanoma, still one of the most deadly diseases in modern medicine, ranks among the greatest challenges that a clinician has to face. Metastatic melanoma also is one of the most profound sources of clinical frustration, since it provides far more ultimately defeating experiences than clinical victories. At the same time, the fascinating biology of melanoma has invited the study of this neuroectodermal tumor as a model system for dissecting many of the key problems of modern oncology, ranging from molecular oncogenesis via the controls of tumor proliferation, apoptosis, invasion, metastasis, and angiogenesis to tumor immunosurveillance and tumor drug resistance. Together with the dire need to develop more effective treatment modalities for improving both life expectancy and quality of life of affected patients, this has made metastatic melanoma a favorite model for the exploration of innovative strategies for tumor management. Encouragingly, many of these have already generated very promising results in animal models. However, this impressive level of research progress in conquering melanoma in the animal room contrasts rather pitifully with the actual progress made on the ward. This CONTROVERSIES feature, therefore, critically and soberly reviews the state of the art of treating metastatic melanoma today (distinguishing between nodal and distant metastases), and sharply defines unresolved paratively neglected key problems. In addition, this feature highlights several novel, provocative, hitherto underappreciated, yet potentially promising treatment approaches that deserve systematic exploration. Hopefully, this will offer further inspiration for the design and pursuit of innovative anti-melanoma strategies off-the-beaten-track. |
11099111 | Expression of involucrin in normal, hyperproliferative and neoplastic mouse keratinocytes. | Involucrin is a protein precursor of the epidermal cornified envelope. Although expression of the human protein has been documented extensively, studies in the mouse have been hampered by a shortage of good antibodies. We describe the production of binant mouse involucrin and preparation of rabbit antisera to the protein that work well by immunohistochemistry and Western blotting. We confirm that in normal mouse epidermis the onset of involucrin expression is in the upper spinous layers and inner root sheath of the hair follicle. Involucrin was also detected in the differentiating epithelial cells of normal tongue, oesophagus and bladder. Involucrin was expressed in a subpopulation of mouse keratinocytes cultured in standard or low calcium medium and the proportion of involucrin-positive cells increased during suspension-induced terminal differentiation. Western blotting of keratinocytes from several inbred mouse strains revealed a remarkable heterogeneity in the electrophoretic mobility of involucrin, reflecting inter-strain variation in the number of tandem repeats in the protein. In the hyperproliferative epidermis of healing wounds involucrin was expressed in most of the suprabasal layers. In epidermal papillomas and carcinomas involucrin expression correlated well with degree of histological differentiation. The sites of expression of the mouse protein were thus the same as those previously reported for human involucrin. With the development of the new antibodies we anticipate that involucrin will e as widely used a marker of keratinocyte differentiation in the mouse as it is in the human. |
11099113 | Parents' and partners' life course and family experiences: links with parent-child relationships in different family settings. | Life course and current family factors associated with individual differences in parent-child relationships were investigated in a sample of 467 children from 192 families, including stepfather, single-parent, stepmother, plex stepfamilies; informants were fathers, mothers, and children. Both positive and negative dimensions of father-child and mother-child relationships were linked to earlier life course experiences of parent and of partner, to current family factors, and to the quality of partner's relationship with the child. The pattern of associations between the adults' life course experiences meant that children were at risk for a "double dose" of less affectionate relationships in families in which parents had experienced early adversities. The significance of biological relatedness, family setting, and child partner relationships was highlighted. |
11099114 | Risk factors for long-term psychological effects of a disaster experienced in adolescence: predictors of post traumatic stress disorder. | This paper examines risk factors for the development of Post Traumatic Stress Disorder (PTSD), and its severity and chronicity, in a group of 217 young adults who survived a shipping disaster in adolescence. The survivors were followed up 5 to 8 years after the disaster. Risk factors examined fell into three main categories: pre-disaster child and family vulnerability factors, including childhood psychopathology; objective and subjective disaster-related experiences; and post-disaster factors, including results from screening questionnaires administered 5 months post-disaster, coping mechanisms adopted subsequently, life events, and availability of social supports. Developing PTSD following the disaster was significantly associated with being female, with pre-disaster factors of learning and psychological difficulties in the child and violence in the home, with severity of exposure to the disaster, survivors' subjective appraisal of the experience, adjustment in the early post-disaster period, and life events and social supports subsequently. When all these factors were considered together, measures of the degree of exposure to the disaster and of subjective appraisal of life threat, and ratings of anxiety obtained 5 months post-disaster, best predicted whether survivors developed PTSD. For those survivors who developed PTSD, its duration and severity were best predicted not by objective and subjective disaster-related factors, but by pre-disaster vulnerability factors of social, physical, and psychological difficulties in childhood together with ratings of depression obtained 5 months post-disaster, and whether survivors received post-disaster support at school. The implications of these findings are considered for targeting assessment and intervention efforts at survivors most at risk of developing difficulties in adjustment following similar traumatic experiences. |
11099115 | Judgements about emotional events in children and adolescents with post-traumatic stress disorder and controls. | Research with clinically anxious adults has revealed that they estimate future negative events as far more likely to occur, relative to healthy controls. In addition, anxious adults estimate that such events are more likely to happen to themselves than to others. Previous research with anxious children and adolescents, in contrast, has revealed no increased probability estimates for negative events, relative to controls, and the events were rated as more likely to happen to others than to the self. The present study followed up these discrepant findings by investigating probability judgements concerning future negative events generated by children and adolescents who had actually experienced an extreme negative event and who met criteria for a diagnosis of Post-traumatic Stress Disorder (PTSD). Control prised a group of healthy participants, and a group of healthy participants whose parents had experienced a trauma and who met criteria for PTSD. The results revealed no overall differences between the clinical group and the controls. However, children and adolescents with PTSD estimated all negative events as significantly more likely to happen to others than to themselves, with this other-referent bias being strongest for events matched to their trauma. In contrast, the two control groups exhibited an other-referent bias for physically threatening events but not for socially threatening ones. Developmental analyses indicated that the strength of the relationship between anxiety and elevated judgements about future negative events declined with age in the control participants but that there was no significant relationship in the groups who had been exposed to trauma. The findings are discussed in the context of the literature on information processing biases and PTSD. |
11099116 | The association between direct and relational bullying and behaviour problems among primary school children. | The prevalence of direct and relational bullying and their differential relationship to behaviour problems in young primary school children was investigated. Individual interviews were conducted with 1982 children aged 6 9 years (mean age 7.6 years) and 1639 pleted the Strength and Difficulties Questionnaire regarding behaviour problems of their children. Of the 1639 children with both data sets, 4.3% were direct bullies, 39.8 % victims, and 10.2% both bullied and were victimised frequently (bully/victims). The rates for relational bullying were 1.1% bullies, 37.9% victims, and 5.9% bully/victims. All children involved in direct bullying had significantly increased total behaviour problems, hyperactivity, conduct problems, and peer problem scores, and lower prosocial behaviour pared to those not involved in bullying (neutrals). Findings were similar for relational bullying involvement and behaviour problems for bully/victims and victims but less pronounced. Relational bullies had the lowest behaviour problem scores while being rated the least prosocially inclined children, consistent with the concept of a cool manipulator. Overall, direct bully/victims and children who were involved in both direct and relational bullying behaviour had the highest rates of behaviour problems. No relationship between victimisation and increased emotional problems were found. Those involved in bullying behaviour who show externalising and hyperactivity problems in primary school may be at increased risk for persistent conduct problems. Different interventions may be needed for those involved in relational bullying only, both direct and relational bullying, and those with additional behaviour problems. |
11099117 | The developmental sequelae of nonorganic failure to thrive. | The developmental sequelae of infant failure to thrive (FTT) were examined in an unreferred group of 6-year-olds with a history of severe nonorganic growth retardation, sampled from a 1-year birth cohort in an inner-city area of South London. Children who failed to thrive in infancy (weight below the third centile for at least 3 months) and their pairwise parisons were originally studied at 15 months, and 42 cases and 42 controls (89.5% of the sample) were followed up. At 6 years, previously growth-retarded children were considerably smaller than parisons, in terms of body mass index (BMI), and height and weight for age Z scores. History of FTT explained substantial variance in weight and BMI at 6 years, with maternal height also contributing to variation in height for age. Child cognitive functioning at 6 years was examined using the McCarthy Scales: cases had more limited quantitative and memory skills parisons, but there was no intergroup variation in general cognitive performance. In contrast to analyses of physical development, failure to thrive did not account for cognitive functioning; maternal IQ was the sole significant predictor of performance on all indices of child cognitive abilities. At 15 months, earlier growth faltering was linked to limitations in mental development, but these findings were not confirmed by the follow-up data: the timing of FTT was not related to cognitive abilities at 6 years. Results correspond to past research indicating that nonorganic failure to thrive is associated with persistent limitations in physical stature. There was little evidence of cognitive disadvantage for case group children at school age, suggesting that the adverse effects of early malnutrition on cognitive functioning appear to diminish over time. |
11099118 | The mother-child relationship following in vitro fertilisation (IVF): infant attachment, responsivity, and maternal sensitivity. | Infant attachment and mother-child interaction were evaluated for 65 primiparous women and their singleton infants conceived through in vitro fertilisation (IVF) and a control group of 61 women and their infants conceived naturally. The sample was enrolled during pregnancy as part of a longitudinal study. At 12 months postpartum, security of infant attachment was assessed using the Strange Situation procedure, and mother-child interaction was assessed in a free play context using the Emotional Availability Scales. IVF children demonstrated predominantly secure attachment relationships with their mothers (64.6% IVF, 55.9% controls), and there were no significant between-group differences in the proportion of pared to control group children classified in any of the secure or insecure attachment groups. Furthermore, there were no significant group differences on maternal (sensitivity, structuring, hostility) or child (responsivity, involving) dimensions of interaction during play. The majority of IVF mothers (86%) were sensitive and their infants responsive (91%). Contrary to expectation, mother's ratings of greater anticipated infant difficultness assessed during pregnancy and higher ratings of infant temperament and behaviour difficulty assessed at 4 and 12 months postpartum were associated with secure attachment relationships and more optimal mother-child interaction in both the IVF and control groups. |
11099119 | The development and adjustment of 7-year-old children adopted in infancy. | The present study (N = 159) provides evidence of an increased risk for behavior problems of infant-placed 7-year-old internationally, transracially adopted children in the Netherlands. However, parents reported more behavior problems for adopted boys than for adopted girls. Notably, about 30% of the adopted children were classified as clinical on the CBCL scale for total problems, which is a much larger percentage than the 10% found in the normative population. It was suggested that these results could be explained by the operation of multiple risk factors before and after adoption placement, e.g. the child's genetic disposition, pre-natal and pre-adoption care, or the child's cognitive understanding of adoption in middle childhood. Also, results suggest that maternal sensitive responsiveness in adoptive families declines in the transition from early to middle childhood. In contrast to the home setting, the adopted children showed favorable behavioral and socioemotional adjustment at school, while their academic achievement and intelligence were in the normal range or above average. In particular Korean children had high IQs: 31% of these children obtained an intelligence score above 120. It was suggested that adoptive parents seem to offer their children sufficient or even more than average cognitive stimulation. Furthermore, adopted girls scored higher in optimal ego-control, petence, and peer group popularity than nonadopted girls from the general population: 30% of the adopted girls were rated as popular by their classmates, pares favorably to the 13% found in the general school population. |
11099120 | Psychiatric comorbidity in children and adolescents with reading disability. | This study investigated the association between reading disability (RD) and internalizing and externalizing psychopathology in a munity sample of twins with (N = 209) and without RD (N = 192). The primary goals were to clarify the relation between RD orbid psychopathology, to test for gender differences in the behavioral correlates of RD, and to test mon familial influences contributed to the association between RD and other disorders. Results indicated that individuals with RD exhibited significantly higher rates of all internalizing and externalizing disorders than individuals without RD. However, logistic regression analyses indicated that RD was not significantly associated with symptoms of aggression, delinquency, oppositional defiant disorder, or conduct disorder after controlling for the significant relation between RD and ADHD. In contrast, relations between RD and symptoms of anxiety and depression remained significant even after controlling orbid ADHD, suggesting that internalizing difficulties may be specifically associated with RD. Analyses of gender differences indicated that the significant relation between RD and internalizing symptoms was largely restricted to girls, whereas the association between RD and externalizing psychopathology was stronger for boys. Finally, preliminary etiological analyses suggested mon familial factors predispose both probands with RD and their non-RD siblings to exhibit externalizing behaviors, whereas elevations of internalizing symptomatology are restricted to individuals with RD. |
11099121 | Assessing exposure to violence using multiple informants: application of hierarchical linear model. | The present study assesses the effects of demographic risk factors on children's exposure to violence (ETV) and how these effects vary by informants. Data on exposure to violence of 9-, 12-, and 15-year-olds were collected from both child participants (N = 1880) and parents (N = 1776), as part of the assessment of the Project on Human Development in Chicago Neighborhoods (PHDCN). A two-level hierarchical linear model (HLM) with multivariate es was employed to analyze information obtained from these two different groups of informants. The findings indicate that parents generally report less ETV than do their children and that associations of age, gender, and parent education with ETV are stronger in the self-reports than in the parent reports. The findings support a multivariate approach when information obtained from different sources is being integrated. The application of HLM allows an assessment of interactions between risk factors and informants and uses all available data, including data from one informant when data from the other informant is missing. |
11099122 | Local and global processing of music in high-functioning persons with autism: beyond central coherence? | A multi-modal abnormality in the integration of parts and whole has been proposed to account for a bias toward local stimuli in individuals with autism (Frith, 1989; Mottron & Belleville, 1993). In the current experiment, we examined the utility of hierarchical models in characterising musical information processing in autistic individuals. Participants were 13 high-functioning individuals with autism and 13 individuals of normal intelligence matched on chronological age, nonverbal IQ, and laterality, and without musical experience. The task consisted of same-different judgements of pairs of melodies. Differential local and global processing was assessed by manipulating the level, local or global, at which modifications occurred. No deficit was found in the two measures of global processing. In contrast, the clinical group performed better than parison group in the detection of change in nontransposed, contour-preserved melodies that tap local processing. These findings confirm the existence of a "local bias" in music perception in individuals with autism, but challenge the notion that it is accounted for by a deficit in global music processing. The present study suggests that enhanced processing of elementary physical properties of ing stimuli, as found previously in the visual modality, may also exist in the auditory modality. |
11099123 | Understanding theory of mind in children who are deaf. | Research on theory of mind began in the context of determining whether chimpanzees are aware that individuals experience cognitive and emotional states. More recently, this research has involved various groups of children and various tasks, including the false belief task. Based almost exclusively on that paradigm, investigators have concluded that although "normal" hearing children develop theory of mind by age 5, children who are autistic or deaf do not do so until much later, perhaps not until their teenage years. The present study explored theory of mind by examining stories told by children who are deaf and hearing (age 9-15 years) for statements ascribing behaviour-relevant states of mind to themselves and others. Both groups produced such attributions, although there were reliable differences between them. Results are discussed in terms of the cognitive abilities assumed to underlie false belief and narrative paradigms and the implications of attributing theory of mind solely on the basis of performance on the false belief task. |
11099128 | Can rabbits tell humans apart?: Discrimination of individual humans and its implications for animal research. | To predict when food reward was available, 12 New Zealand White rabbits were trained to discriminate between two humans. All subjects had significantly higher response rates and greater behavioral arousal in the presence of the positive stimulus person. The ability to discriminate between individual humans sets the stage for unanticipated Pavlovian conditioning, which may have considerable implications for animal research in behavioral and biomedical settings. |
11099129 | Modified procedure for implantation of subcutaneous central venous access devices in macaques (Macaca mulatta). | A nonhuman primate prising adult male rhesus monkeys (Macaca mulatta) with chronically indwelling subcutaneous central venous access devices provides a unique opportunity to determine plasma pharmacokinetics of new drugs such as anticancer and anti- retroviral agents. The central venous access we use is a low-profile, single-septum, titanium port that is attached to a radiopaque, indwelling catheter; the catheter is implanted in an internal jugular vein. plication following placement of the venous access device was migration of the catheter tip. We therefore modified the standard procedure by cutting the silicone catheter and introducing the rigid connector to secure the catheter to the vessel at the insertion site (approximately 9 to 13 cm from the distal end of the catheter). Prior to the use of the connector, three of five catheters migrated within 4 weeks after placement. In contrast, all 13 internal jugular catheters with connectors have remained patent without migration of the catheter tip. Therefore, incorporation of the catheter connector appears to have eliminated the problem of catheter migration. |
11099130 | Evaluation of insulin resistance in two kinds of South American camelids: llamas and alpacas. | Insulin resistance was evaluated in South American camelids, llamas and alpacas, by use of the minimal model test and the insulin tolerance test. Animals were catheterized for long-term studies and tamed to minimize stress during evaluation. Results indicated a low insulin sensitivity index (SI) = 0 to 0.97, median = 0.39 x 10(-4) min/uIU x ml, about a fifth the value in other mammals and humans. The KITT was between 1.43 and 3.19 %/min, also significantly lower than that reported for humans. Glycosylated hemoglobin concentration was 6%, and HbAlc concentration was 5.5%; red blood cell lifetime, as measured by use of the 51Cr method, was 120 days, similar to the value in humans. We concluded that llamas and alpacas have naturally higher blood glucose concentration than do humans and other mammals during the glucose tolerance test. Using the same mathematical tools to evaluate glucose metabolism as those used in people, South American camelids appear to be resistant to insulin. Thus, the South American camelid may be a useful new animal model for the study of sugar metabolism and various facets of diabetes mellitus, especially protection from the deleterious effects of glycosylation. |
11099131 | Leukocyte mobilization induced by hypervolemia is due to a combined alpha- and beta-adrenoceptor activation. | A phenomenon of leukocytosis induced by hypervolemic stress was discovered. Although a single injection of 350 microl of saline (equivalent to approx. 70 ml in humans, 1 ml/kg of body weight) did not have an effect on the leukocyte counts in long-term intravenously cannulated, freely behaving rats, a single injection of 750 microl of saline (equivalent to approx. 150 ml in humans, 2.1 ml/kg) induced rapid leukocytosis of 160% within 1 minute followed by a gradual increase up to 180% after 1 hour. Measurement of serum norepinephrine concentration revealed a significant increase in rats of the hypervolemic pared with those of the low volume group. Pretreatment with either the beta-adrenoceptor antagonist nadolol or the selective alpha2-adrenoceptor antagonist yohimbine prevented both leukocyte peaks in the high volume group, suggesting bined receptor activation. This critical dependence of leukocyte counts on changes in blood volume should be taken into consideration in experiments with laboratory animals (the quantity of volume applications can falsify results of experiments). |
11099133 | Neuropathology of bouncer Long Evans, a novel dysmyelinated rat. | Spontaneous animal mutants affected by abnormal formation of myelin in the central nervous system (CNS) are useful in studies on myelinogenesis and remyelination leading to better understanding of cellular and molecular interactions involved in myelin repair. A novel rat mutant, Bouncer Long Evans (LE-bo) is severely dysmyelinated, but with exceptional longevity, and its clinical and pathologic phenotype are described. |
11099134 | Variant form of diffuse corporal gastritis in NHE2 knockout mice. | Mice lacking the NHE2 Na+/H+ gene develop gastritis of the glandular mucosa as early as the tenth day of life, achieving maximal intensity of inflammation from 17 to 19 days after birth and maximal atrophy at one year. We assessed the effects of this process in such mice to 16 months of age. The stomach of NHE2 null mutants was examined at 10, 17 to 20, 24 to 35 and 49 to 70 days, and at 12 to 16 months. The NHE2 wild-type (+/+) and NHE2 heterozygous (+/-) mice pared with the NHE2 homozygous mutant mice (-/-). The stomach of the mutant mice at all ages was characterized by a substantially reduced number of parietal cells. The 10-day-old mouse stomach had a transmural infiltrate of primarily neutrophils. With increasing age, neutrophils were replaced by lymphocytes and plasma cells in the glandular mucosa of the mutant mice. Young adult 49- to 70-day-old mice had surface cell hyperplasia and expansion of the replicating cell population. Hyperplasia of enterochromaffin-like cells and antral gastrin cells panied profound fundic gland and surface cell hyperplasia, and became progressively more severe with increasing age of the NHE2-/- mice. Neoplasms were not found in the mutant or control mice. This gastritis differs from that of autoimmune gastritis in that it is transmural, begins in infancy, and is associated with a predominantly neutrophilic infiltrate in its early stages. Some of the histologic changes in the adult mice can be explained on the basis of prolonged achlorhydria. This mouse may be a suitable model for prolonged effects of achlorhydria. |
11099132 | Effect of mouse strain and age on detection of mouse parvovirus 1 by use of serologic testing and polymerase chain reaction analysis. | Detection of mouse parvovirus 1 (MPV) depends on use of serologic and polymerase chain reaction (PCR) assays. These assays were evaluated for their ability to detect virus-specific antibodies or viral DNA in multiple strains and ages of mice inoculated with MPV. |
11099136 | Procedure for laryngotracheal separation in the goat: development of a new animal model for analysis of craniofacial growth. | Most animal models used to study the process of postnatal craniofacial growth require direct manipulation of the craniofacial area, a growth period, then evaluation of the area. However, the scar tissue associated with direct manipulation of the craniofacial structures can produce growth abnormalities that are unrelated to the manipulation itself. To avoid this confounding variable in the study of craniofacial growth, we developed an animal model that involves laryngotracheal separation in a young animal. Our pletely separates the trachea from the upper aerodigestive tract and removes the site of scar tissue formation from the region of investigation. The tracheal stomas of the goats we describe were maintained for as long as 9 months. Unlike human patients, goats with laryngotracheal separation require laryngectomy tubes to prevent life-threatening stenosis of the tracheal stoma. Here we describe the operative procedure and post-operative care required for this new animal model. |
11099135 | Behavioral, clinical, and physiologic analysis of mice used for ascites monoclonal antibody production. | The effects of pristane inoculation, ascites accumulation, peritoneocentesis, and analgesics on the well-being of mice used in monoclonal antibody (MAb) production protocols were investigated. |
11099138 | Ringtail in suckling Munich Wistar Fromter rats: a histopathologic study. | Ringtail is a pathologic condition of the tail of rats and other rodents that is traditionally attributed to low environmental humidity, although dietary deficiencies, genetic susceptibility, environmental temperature, and degree of hydration of the animal also have been suggested as possible causes. To the authors' knowledge, a detailed histopathologic study that may serve to shed light on the etiopathogenesis of this disease has not yet been published. We describe the histologic findings of ringtail observed in 12 suckling Munich Wistar Fromter (MWF) rats from two litters. Epidermal hyperplasia characterized by orthokeratotic and parakeratotic hyperkeratosis and acanthosis was observed in all affected rats. Numerous often dilated vessels were present in the dermis of tails that appeared of red/brown color at gross examination. In severe cases, the dilated vascular structures were thrombotic and panied by dermal hemorrhages and focal coagulative necrosis of the overlying epidermis. These findings suggest that epidermal acanthosis and hyperkeratosis are the main and primary events in the development of ringtail. To clarify the cause of this disease, future studies should be focused on the numerous factors that can induce such epidermal changes. |
11099137 | Isolation and characterization of Corynebacterium ulcerans from cephalic implants in macaques. | To determine the prevalence of colonization by Corynebacterium ulcerans, we cultured samples from the cephalic implant-skin margin and pharynx of 26 rhesus macaques and one pig-tailed macaque. All but one of the samples from the cephalic implants yielded a mixed population of bacteria. C. ulcerans grew from the cephalic implants in 56% and from the pharynx in 3% of the implanted animals. We screened nine of these isolates for diphtheria toxin (DT) and phospholipase D (PLD). Polymerase chain reactions (PCR) failed to identify DT in any of the tested isolates, which also lacked DT activity in Elek tests. However, all nine isolates tested had PLD toxin activity as determined by conjoint hemolysis on sheep blood agar plates in the presence of equi factor (Rhodococcus equi). In addition, PCR assays and Southern blot hybridization confirmed the presence of pld in the isolates. The role of the PLD toxin in promoting colonization of cephalic implants by C. ulcerans is unknown. We found C. ulcerans to be a frequent contaminant of the cephalic implant-skin margin. Further studies are necessary to investigate the relative clinical importance of this organism and the efficacy of various implant maintenance protocols in preventing infection. |
11099139 | Spontaneous intestinal adenocarcinoma in geriatric macaques (Macaca sp.). | Intestinal adenocarcinoma appears to be the mon malignant neoplasm in macaques, and is a substantial cause of morbidity and mortality in the elderly. |
11099140 | Use of injectable potassium chloride for euthanasia of American lobsters (Homarus americanus). | Potassium chloride (KCl: 330 mg/ml) was assessed as an euthanasia agent in American lobsters (Homarus americanus). Two groups of 10 lobsters (408.2 to 849.9 g) were maintained at 11.9 to 12.1 degrees C ('warm') and 1.5 to 2.5 degrees C ('cold') to evaluate the possible effect of ambient temperature on response to KCl. Death was defined as time of cardiac arrest, as viewed and measured by use of ultrasound. The KCl solution was injected (100 mg of KCl/100 g of body weight) at the base of the second walking leg to flood the hemolymph sinus containing the ventral nerve cord with potassium. Disruption of this 'central nervous system' was immediate, followed by cardiac arrest within 60 to 90 seconds. Group median ( +/- SD) baseline heart rate was 42 +/- 14 'warm' and 36 +/- 5 'cold' beats per minute. Time until cardiac arrest ranged from 35 to 90 (57 +/- 18) seconds in the 'warm' group and from 40 to 132 (53 +/- 34) seconds in the 'cold' group. There was no significant difference between group medians for either parameter. Histologic lesions were limited to mild to moderate acute degeneration, characterized by cell swelling, loss of contraction bands, and occasional mild cytoplasmic vacuolation of skeletal muscle at the injection site. Injectable KCl solution was an effective, reliable method for euthanasia of H. americanus. |
11099142 | Environmental enrichment-related injury in a macaque (Macaca fascicularis): intestinal linear foreign body. | A three-year old male cynomolgus macaque (Macaca fascicularis) presented with clinical signs of anorexia and depression that decreased over a 48-hour period. Results of abdominal radiography abdominocentesis, blood biochemical analysis and CBC suggested septic peritonitis. Exploratory laparotomy revealed multiple perforations along the mesenteric border of the small intestine. Necropsy revealed masses of fibrous material in the stomach and cecum. Multiple mucosal ulcerations, as well as linear fibrous material, were found in the small intestine. The ulceration, perforations, and septic peritonitis were attributed to the ingestion of rope that had been attached to the animal's cage as an environmental-enrichment device. |
11099141 | Serial laparoscopic biopsies of liver and spleen from Schistosoma-infected baboons (Papio spp.). | To obtain large, serial biopsy samples from the liver and spleen by using laparoscopy. Large samples were needed for measurement of inflammatory mediators during various stages of schistosomiasis. |
11099143 | Laryngeal chondrosarcoma: a 24-year experience at the Royal National Throat, Nose and Ear Hospital. | This paper presents a review of the experience of 12 patients with a of the larynx treated at The Royal National Throat, Nose and Ear Hospital, London, over the last 24 years. This represents the largest European series and the third largest in the world. a is the most frequent non-epithelial malignant tumor of the larynx, with 83.3% of cases arising from the cricoid cartilage in our series. We have shown that deep wedge biopsy with a CO2 laser, aided puterized tomography scanning, gives the most reliable diagnosis. Laryngeal a is characterized by indolent growth, a potential for local recurrence and, infrequently, by metastases. The treatment details of our patients are discussed. Adequate partial resection is often successful and use of CO2 laser as the initial treatment in five of these cases is presented. |
11099144 | Auditory dysfunction in stroke. | The auditory and vestibular systems share the same end organ and cranial nerve, yet vestibular signs and symptoms mon with stroke, whereas hearing disturbances are much less frequent. Several reasons would appear to account for this striking dissimilarity. One is that the auditory pathway is less ubiquitous than the vestibular pathways. The likelihood that a stroke involves the auditory pathway is, therefore, less on this basis alone. A second difference, to our knowledge not previously reported, is that the auditory pathway is often spared by the mon strokes. This is because major parts of the auditory pathway, such as the cochlear nucleus, inferior colliculus and medial geniculate body, have multiple sources of blood supply. A third well-recognized factor is the redundancy of the central auditory system and its strong bilateral representation above the level of the cochlear nuclei. Consequently, rostral to the cochlear nuclei gross deficits in hearing, such as those measured by standard pure-tone audiometry and speech discrimination, only occur if lesions are bilateral. Furthermore, widespread bilateral lesions of the auditory system typically render the patient unable to respond or are patible with life. In contrast, language disorders are more frequent because language is usually unilaterally represented in the cortex. Certainly, cerebral stroke often includes the auditory system, resulting in various types of auditory disorders, but most hemispherical lesions produce subtle hearing dysfunctions that can only be detected with sophisticated psychoacoustic and electrophysiological testing. The purpose of this review is to provide an overview of the auditory system and its blood supply and to review how auditory processing can be affected by stroke. Psychoacoustic and electrophysiological test procedures for identifying lesions in the central auditory system are described. The literature of hearing disorders due to stroke is reviewed and illustrative cases are presented. |
11099145 | Extracellular adenosine 5'-ATP-induced calcium signaling in isolated vestibular ganglion cells of the guinea pig. | Extracellular adenosine 5'-triphosphate (ATP)-induced intracellular calcium concentration ([Ca2+]i) changes in acutely isolated vestibular ganglion cells (VGCs) of the guinea pig were investigated using the Ca2+ -sensitive dye Fura-2. Extracellular ATP induced an increase in [Ca2+]i in VGCs in a dose-dependent manner. ATP induced an increase in [Ca2+]i even in the absence of extracellular Ca2+ (1 mM Ethylene Glycol-bis (beta-aminoethyl Ether) N,N,N',N'-Tetraacetic Acid (EGTA)), thus suggesting that ATP induces Ca2+ release from the intracellular stores. The P2-receptor antagonists suramin and reactive blue 2 inhibited the ATP-induced [Ca2+]i increase in a dose-dependent manner. The P1-receptor agonist adenosine did not induce any changes in [Ca2+]i. These results suggest that VGCs may possess a P2-purinergic receptor but not a P1-purinergic receptor. La3+, a receptor-mediated calcium channel blocker, inhibited the ATP-induced [Ca2+]i increase but, in contrast, nifedipine, a L-type calcium channel blocker, did not. These results suggest that ATP induces both a Ca2+ -release from the intracellular stores and a Ca2+ influx from the extracellular space through La3+ -sensitive and nifedipine-insensitive Ca2+ channels in VGCs. Our results also suggest that extracellular ATP may act as a neurotransmitter or neuromodulator of the vestibular peripheral system in the guinea pig. |
11099147 | Eustachian tube function varies over time in children with secretory otitis media. | Impaired opening and closing functions of the Eustachian tube are considered to be pathogenic factors in secretory otitis media (SOM). As the clinical course of SOM is variable, the variability of tubal function is of interest. We aimed to explore the short- and long-term variability of tubal opening and closing functions in SOM. The prised 42 ears in 21 children (13 males and 8 females) with tympanostomy tubes due to SOM. The middle ear pressure was recorded during repeated passive forced openings, equalization of + 100 daPa and - 100 daPa by swallowing, Valsalva inflation and forceful sniffing. Test sessions were performed twice (separated by 30 min) on each of 2 days, with a mean interval of 3.7 months in between. In the forced opening test there was a considerable intra-individual variability over time. Expressed as SD of the mean, the variability of the forced opening and closing pressures in individual ears was on average 15% and 23%, respectively, between sessions and 20% and 30% respectively, between test days. In the equalization, Valsalva and sniff tests the rates of responses that changed from positive to negative between sessions and test days ranged from 12% to 33%. Female gender and retraction pockets were related to poorer opening function in the forced opening test. Ears with serous effusion (in contrast to mucoid) showed a similar trend and also a lower occurrence of positive equalization, Valsalva and sniff tests. It was concluded that Eustachian tube opening and closing functions are highly variable in ears with SOM. Consequently, single tubal function tests have low value when used as a prognostic tool in individual ears. |
11099146 | Distribution of HLA-A, -B and -DRB1 alleles in patients with sudden sensorineural hearing loss. | This study was performed to investigate the association between human leukocyte antigen (HLA) and susceptibility to sudden sensorineural hearing loss in the Korean population. HLA-A and HLA-B typing using a standard microlymphocytotoxicity technique and HLA-DRB1 genotyping were performed in 35 patients with sudden sensorineural hearing loss and in 206 healthy controls. Prednisone (usual dose 60 mg/day) was administered for 6 days and tapered for an additional 4-6 days. Both initial hearing levels at the onset of deafness and final hearing levels after treatment were examined and evaluated for association with HLA alleles. The frequency of HLA-DRB1*14 was increased in patients with sudden sensorineural hearing pared with controls (relative risk [RR] = 2.7, p = 0.016). The frequencies of HLA-A2, -A31, -B52, -B61, -DRB1*04, -DRB1*11 and -DRB1*12 were slightly higher than in the controls, but did not reach statistical significance. When an association between the treatment results and HLA alleles was also evaluated, the frequency of HLA-DRB1*04 was found to be increased in the patients who did not respond to steroid pared with both patients who responded well to steroid (50%, vs 16%, p = 0.034) and controls (RR = 3.0, p = 0.046). These results suggest that there is an association between HLA-DRB1*14 and disease susceptibility and that the presence of HLA-DRB1*04 may be an useful marker for predicting a poor prognosis in Korean patients with sudden sensorineural hearing loss. |
11099148 | Computerized electronystagmography: normative data revisited. | This study provides normative data puterized electronystagmography (ENG) testing of 40 healthy subjects with an average age of 45 years. The clinical test prises an extensive vestibular examination with oculomotor, positional, rotary chair and caloric tests. The results show that with puterized ENG set-up considerable variabilities of 22% for rotary chair asymmetry and 19% for caloric labyrinth asymmetry remain. |
11099149 | Bone-conducted evoked myogenic potentials from the sternocleidomastoid muscle. | The aim of this study was to show that bone-conducted clicks and short tone bursts (STBs) can evoke myogenic potentials from the sternocleidomastoid muscle (SCM) and that these responses are of vestibular origin. Evoked potential responses to bone-conducted auditory stimuli were recorded from the SCMs of 20 normal volunteers and from 12 patients with well-defined lesions of the middle or inner ear or the VIIIth cranial nerve. The subjects, who had various labyrinthine and retro-labyrinthine pathologies, included five patients with bilateral profound conductive hearing loss, two with bilateral acoustic neuroma post-total neurectomy and five with bilateral sensorineural hearing loss. Air- and bone-conducted evoked myogenic potentials in response to clicks and STBs were recorded with surface electrodes over each SCM of each subject. In normal subjects, bone- and air-conducted clicks and STBs evoked biphasic responses from the SCM ipsilateral to the stimulated ear. The bone-conducted clicks evoked short-latency vestibular-evoked myogenic potential (VEMP) responses only in young subjects or in subjects with conductive hearing loss. STBs evoked VEMPs with higher amplitude and better waveform morphology than clicks with the same acoustic intensity. Patients with total VIIIth cranial nerve neurectomy showed no responses to air- or bone-conducted click or STB stimuli. Clear VEMP responses were evoked from patients with conductive or sensorineural hearing loss. It is concluded that loud auditory stimuli delivered by bone- as well as air conduction can evoke myogenic potentials from the SCM. These responses seem to be of vestibular origin. |
11099150 | The role of neck afferents in subjective orientation in the visual and tactile sensory modalities. | We studied the influence of neck afferents on the perception of orientation. In Experiment 1, we investigated the effect of head tilt on the subjective vertical in both the visual and tactile modalities. The results showed that head tilt triggers an Aubert effect in the visual modality and a Müller effect in the tactile modality. Significant positive correlations between the two adjustment modalities were restricted to head tilt to the left. In Experiment 2, we investigated the role of neck afferents on tactile orientation in seated and supine positions. The results showed that, in the supine position, the tactile E-effect was twice as large as in the seated position. These experiments confirm that tactile perception of orientation is affected by neck afferents, and show that the influence of neck afferents is limited by relevant gravitational cues. |
11099151 | Analysis of magnetic resonance imaging acoustic noise generated by a 4.7 T experimental system. | High intensity acoustic noise is an undesirable side-effect in magnetic resonance imaging (MRI) that can cause fort and hearing loss in patients and may be an impediment in functional MRI (fMRI) studies of the auditory system. Experimental MRI systems with high magnetic field strengths may generate acoustic noise of higher sound pressure levels (SPLs) than conventional 1.0 and 1.5 T clinical systems. We measured the SPL and spectral content of the acoustic noise generated by the Bruker Biospect 47/40 4.7 T experimental MRI system during scanning monly used in animal testing. Each sequence generated acoustic noise of high SPL, rapid pulse rates, amplitude-modulated pulse envelopes and multi-peaked spectra. The rapid acquisition with enhancement sequence with a 0.25 mm slice thickness generated SPLs of up to 129 dB peak SPL and 130 dB (A). Fourier analysis of the spectral content of the acoustic noise generated by each MRI sequence showed a wide band of acoustic energy with spectral peaks from 0.2-5 kHz. The intense MRI acoustic impulse noise generated by the 4.7 T system may cause masking of stimuli used in fMRI of the auditory cortex, reduce the hearing acuity of experimental animals and present a risk for unprotected human ears. |
11099153 | Spontaneous firing activity of cortical neurons in adult cats with reorganized tonotopic map following pure-tone trauma. | We hypothesized that moderate sensorineural hearing loss resulting from acoustic trauma would cause (i) a change in the cortical tonotopic map, (ii) an increase in spontaneous activity in the reorganized region and (iii) increased inter-neuronal synchrony within the reorganized part of the cortex. Five kittens were exposed to a 126 dB sound pressure limit tone of 6 kHz for 1 h at both 5 and 6 weeks of age. Recordings were performed 7-16 weeks after the exposure. Auditory brainstem response thresholds for frequencies above 12 kHz were increased by 30 dB on average relative to those in normal cats. Tonotopic maps in the primary auditory cortex were reorganized in such a way that the area normally tuned to frequencies of 10-40 kHz was now entirely tuned to 10 kHz. Spontaneous firing rates were significantly higher in reorganized areas than in normal areas. In order to test for changes in inter-neuronal synchrony, cross-correlation analysis was done on 225 single-unit pairs recorded in the traumatized cats. For the single- and dual-electrode pairs there was no significant difference in peak cross-correlation coefficients for the firings of simultaneously recorded cells between normal and reorganized areas. However, the percentage of correlations that differed significantly from zero was higher in the reorganized area than in the normal area. This suggests a potential correlation between cortical reorganization, increased spontaneous firing rate and inter-neuronal synchrony that might be related to tinnitus found in high-frequency hearing loss induced by acoustic trauma. |
11099152 | Long-term changes in middle latency response and evidence of retrograde degeneration in the medial geniculate body after auditory cortical ablation in cats. | Short- and long-term changes in the middle latency response (MLR) after bilateral ablation of the auditory cortices were studied in awake cats. The amplitude of the negative peak with a latency of about 15 ms (NA) decreased to 60% of the original value 1 week after ablation (short-term change). In the long term, i.e. 11-30 months, NA either decreased further (decreased group) or remained unchanged (non-decreased group). A histological study with light microscopy revealed degeneration of neurons in the ventral nucleus of the medial geniculate body (MGv) in the decreased group, whereas the neurons in this region were preserved in the non-decreased group. This study suggests that long-term changes in NA reflect retrograde degeneration in the MGv after auditory cortical ablation. |
11099154 | Nasal secretion in ragweed-sensitized dogs: effect of leukotriene synthesis inhibition. | Allergic rhinitis is an inflammatory disease associated with local leukotriene release during periods of symptoms. Zileuton, a leukotriene synthesis inhibitor, is known to inhibit the release of leukotriene B4. Because we previously showed that leukotriene B4 is a potent mediator of neutrophil-dependent nasal secretion, we investigated whether Zileuton inhibited allergen-induced nasal secretion. Using a newly developed method for isolating and superfusing a nasal segment, we examined the effect of Zileuton on nasal secretion and neutrophil recruitment in ragweed-sensitized dogs. Instillation of ragweed into the nasal segment caused time-dependent increases in the volume of airway fluid and the recruitment of neutrophils. Zileuton prevented ragweed-induced neutrophil recruitment and nasal secretion. These results indicate that leukotrienes are important mediators of allergy-induced nasal secretion in dogs. Future clinical studies in allergic patients will determine whether there is a therapeutic role for leukotriene synthesis inhibitors in modulating neutrophil recruitment and hypersecretion in the nose. |
11099155 | Effects of anti-VLA-4 monoclonal antibody treatment in murine model of allergic rhinitis. | In order to study the role of VLA-4 in allergic rhinitis, the effects of anti-mouse VLA-4 monoclonal antibody (mAb) were evaluated in a murine model. BALB/c mice were sensitized first by i.p. injections (general sensitization) and then by daily nasal dripping of antigen (local sensitization) before performing a nasal antigen challenge. The mAb was applied either before the antigen challenge (BC group), before the local sensitization (BL group) or before the general sensitization (BS group). The effects were evaluated in terms of antigen-induced early-phase nasal symptoms (sneezing), late-phase nasal eosinophilia and the serum level of antigen-specific IgE. Antigen-induced nasal eosinophilia was significantly (p = 0.009) reduced in the BL group but not in the BC group (number of eosinophils = 114 +/- 15.1, 244 +/- 52.8 and 347 +/- 50.5 in the BL, BC and control groups, respectively). The serum level of the specific IgE was also significantly (p = 0.038) reduced in the BL group but not in the BC group (optical density = 1.18 +/- 0.07, 1.28 +/- 0.13 and 1.58 +/- 0.14 in the BL, BC and control groups, respectively). The suppressive effect on sneezing was not significant in either the BL or BC groups. In the BS group, suppressive effects on antigen-induced nasal responses and the specific IgE level were not statistically significant. These findings suggest that VLA-4 plays an important role in the topical booster or priming effects during repeated nasal antigen exposures in pre-sensitized animals. |
11099156 | Scanning electron microscopic study of the neuromuscular junctions of the cricothyroid and thyroarytenoid muscles in rats. | Neuromuscular junctions were observed in the cricothyroid (CT) and thyroarytenoid (TA) muscles of adult rats by scanning electron microscopy after removing the intramuscular connective ponents using the HCI hydrolysis method. Morphologically, the junctions were classified into three types in the CT muscle and two types in the TA muscle, based on the structural characteristics of the subneural apparatuses, including junctional folds. In the CT muscle, type 1 junctions (32%) consisted of more than 15 cup-like depressions with slit-like junctional folds. Type 2 junctions (20%) were characterized by approximately 10 cup-like depressions with a small number of pit- or slit-like junctional folds. Type 3 junctions (48%) had irregular labyrinthine gutters with slit-like junctional folds. In the TA muscle, type 1 (82%) and 2 (18%) junctions had similar structures to type 1 and 2 junctions in the CT muscle, respectively. Histochemical studies using myosin adenosine triphosphatase staining showed that both CT and TA muscles predominantly consisted of type II muscle fibers (78% and 82%, respectively), and that the diameter of type II fibers was larger than that of type I fibers. These findings suggest that the type 2 junction belongs to type I muscle fibers, while both type 1 and type 3 junctions belong to type II fibers, and that the type 3 junction is a structural variation of the type 1 junction. The significance of the structural differences of the subneural apparatuses in the intrinsic laryngeal muscles is discussed briefly. |
11099157 | Acoustic analyses clarify voiced-voiceless distinction in tracheoesophageal speech. | In order to clarify the ability of the voice to achieve voiced voiceless distinction in [ce1]tracheoesophageal (TE) speech, acoustic cues such as closure duration, onset and offset of vibration during closure period and voice onset time (VOT), in conjunction with intraoral pressure, were analyzed in 40 TE speakers. Both closure period and VOT during [p] production were longer in TE speakers with high pared with laryngeal speakers; during [b] production these parameters were similar between the two groups. TE speakers with high intelligibility and laryngeal speakers showed significant differences between [p] and [b] production in terms of both closure duration and VOT. TE speakers with low intelligibility of [b] had higher values of VOT during [b] pared with those with high intelligibility. TE speakers with low intelligibility of [p] had lower values of VOT during [p] pared with those with high intelligibility. It is concluded that these characteristic acoustic cues reflect voicing ability in TE speech. |
11099158 | Correlation between glottal area and photoglottographic signal in normal subjects. | Photoglottography (PGG) is an established technique for depicting the vibratory patterns of the vocal folds. The present study investigates the correlation between the glottal area and the corresponding PGG signal. Six normal (five male, one female) subjects who did not use their voices professionally were investigated during constantly sustained phonation at spontaneous pitches. Laryngostroboscopy was performed bination with PGG. The simultaneously recorded laryngostroboscopic images and PGG signals were directly digitized and stored on puter. The correlation between the glottal area and the corresponding PGG amplitudes across each vibratory cycle of the vocal folds was calculated and they were found to be highly and positively correlated (r = 0.973, p < 0.001). The PGG signal reflects changes in the glottal area during the vibration cycle of the vocal folds. The proposed simultaneous laryngostroboscopic and PGG technique has proved to be useful for facilitating the interpretation of changes in glottal area. |
11099159 | Preoperative virtual endoscopy and three-dimensional imaging of the surface landmarks of the internal carotid arteries in trans-sphenoidal pituitary surgery. | In trans-sphenoidal pituitary adenoma surgery the sella turcica is opened between the internal carotid arteries. Three-dimensional image processing methods were applied in this study to avoid the risk of damaging the arteries during the opening of the anterior wall of the sella. By using graphical software it was possible bine the anatomies of the carotid arteries and the sellar wall into one non-perspective three-dimensional image. With a perspective image (virtual endoscopy), the sphenoid sinus landmarks were presented as if looking through a nasoendoscope. This also facilitated preoperative planning but the non-perspective images, with the carotid arteries marked, were found to be the most useful and suitable for clinical routine. The pituitary tumor itself and its relations with the adjacent structures were best evaluated from magnetic resonance imaging scans but, for the opening of the sellar wall and in the three-dimensional orientation with endoscopy, puterized tomography imaging with the carotid arteries marked was found to be helpful. |
11099161 | Diminished posttetanic potentiation in failing human myocardium. | In heart failure a decreased function of SERCA 2 has been demonstrated. The present study aimed at investigating the relation between sarcoplasmic reticulum-Ca2+-load (SR-Ca2+-load) and the activity of the SERCA 2. SR-Ca2+ load was evaluated by measuring posttetanic potentiation (PTP) in human nonfailing (NF, n = 10) and endstage failing myocardium (DCM, n = 11). In addition, the effect of cyclopiazonic acid (CPA), a specific inhibitor of SERCA 2, on PTP was studied in both NF and DCM. In crude membrane preparations from the same hearts the maximal SERCA 2 activity was determined and correlated with the PTP. In failing myocardium the PTP was significantly pared to nonfailing myocardium (13.7+/-0.75 mN/mm2 vs. 17.1+/-1.55 mN/mm2, p<0.05, +/- SEM). When PTP was studied in the presence of increased extracellular Ca2+-concentrations, the difference between NF and DCM was further pronounced. CPA decreased PTP in both nonfailing and failing human tissue. The maximal SERCA 2 activity was significantly reduced in failing myocardium (NF 267+/-18.5 nmol ATP/mg protein x min(-1) vs. DCM 191+/-13.4 nmol ATP/mg protein x min(-1), p<0.05, +/- SEM). Correlation of the PTP and maximal SERCA 2 activity revealed a close correlation between both parameters in NF and DCM. In summary, the presented results suggest that reduced SERCA 2 activity in DCM influences posttetanic force potentiation probably through a reduced SR-Ca2+-load. |
11099160 | Inhibition of carnitine synthesis modulates protein contents of the cardiac sarcoplasmic reticulum Ca2+-ATPase and hexokinase type I in rat hearts with myocardial infarction. | It was previously reported that inhibition of carnitine synthesis by 3-(2,2,2-trimethyl-hydrazinium) propionate (MET-88) restores left ventricular (LV) systolic and diastolic function in rats with myocardial infarction (MI). Preservation of the calcium uptake function of sarcoplasmic reticulum Ca2+-ATPase (SERCA2) is one of the possible mechanisms by which MET-88 alleviates hemodynamic dysfunction. To test this hypothesis, the effects of MET-88 on protein content of SERCA2 were evaluated using the same rat model of heart failure. Myocardial protein content of hexokinase, which is one of the key enzymes of glucose utilization, was also measured. Either MET-88 (MET-88 group) or a placebo (MI group) was administered for 20 days to rats with MI induced by coronary artery ligation. The control group underwent sham surgery (no ligation) and received placebo. In LV myocardial homogenates, the myocardial SERCA2 protein content was 32% lower (p<0.05) in the MI group than in the control group. However, in the MET-88 group myocardial SERCA2 content was the same as in the control group. Hexokinase I protein content was 29 % lower (p<0.05) in the MI pared with the control. In contrast, hexokinase II protein content did not differ significantly among the three groups. Consequently, inhibition of carnitine synthesis ameliorates depression of SERCA2 and hexokinase I protein content which may reduce tissue damage caused by MI. |
11099162 | Ventricular fibrillation threshold and local dispersion of refractoriness in isolated rabbit hearts with left ventricular dysfunction. | Patients with congestive heart failure or left ventricular dysfunction (LVD) have a high incidence of ventricular tachyarrhythmias and sudden cardiac death. In addition to structural, metabolic and neuroendocrine changes, mechanoelectrical feedback may play a role in arrhythmogenesis in heart failure. Three groups of rabbits (n = 10 for each) were studied: chronic coronary ligation with ejection fraction (EF) > or = 0.45 or < 0.45, and sham-operated controls. Ventricular fibrillation (VF) thresholds were measured at LV pressures of 0 and 40 mm Hg during modified Langendorff perfusion. Intervals between local activations during VF (VFI) were used as an index of refractoriness. Global dispersion was expressed as coefficient of variation of VFI; local dispersion by maximum difference in VFI between adjacent sites. Median VF threshold was lower at 0 mm Hg in the lower EF pared to controls (30 vs. 67.5 mA, P<0.05). VF threshold in control hearts was lower at 40 mm Hg than at 0 mm Hg (P<0.01), but there was no further reduction in threshold in LVD hearts at 40 mm Hg. Global dispersion of VFI did not differ significantly between groups. Local dispersion of VFI in the lower EF group was greater than in controls at 0 mm Hg in the infarct border zone (P<0.05). At 40 mm Hg, local dispersion of VFI in zones bordering and remote from the infarct were greater in both LVD groups than in controls (P<0.05). Local inhomogeneity of refractoriness is more marked in the infarct border zone, but latent abnormalities are evident in normal myocardium of rabbits with left ventricular dysfunction and are revealed by left ventricular distension. |
11099163 | Complementary cardioprotective effects of flavonoid metabolites and terpenoid constituents of Ginkgo biloba extract (EGb 761) during ischemia and reperfusion. | Hemodynamic and electron spin resonance (ESR) analyses were performed on isolated ischemic and reperfused rat hearts to assess the cardioprotective and antioxidant effects of therapeutically relevant concentrations of Ginkgo biloba extract (EGb 761; 5, 50 or 200 microg/ml), its terpenoid constituents (ginkgolide A; 0.05 microg/ml and ginkgolide B; 0.05, 0.25 or 0.50 microg/ml), and a terpene-free fraction of EGb 761 (CP 205; 5 or 50 microg/ml). Hearts underwent 10 min of low-flow ischemia, 30 min of no-flow global ischemia, and 60 min of reperfusion. Test substances were added to the perfusion fluid during the last 10 min of control perfusion, low-flow ischemia and the first 10 min of reperfusion. A separate group of rats was treated with CP 205 (60 mg/kg/day; p.o.) for 15 days, after which the hearts were perfused with plain buffer. In ESR experiments, the spin-trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) was added to the perfusate to determine the effects of treatments on post-ischemic myocardial free radical generation. Results showed that in vitro exposure of hearts to EGb 761 (5 or 50 microg/ml) or to ginkgolides A and B (both at 0.05 microg/ml), or in vivo pretreatment of the rats with CP 205 delayed the onset of contracture during ischemia. The strong reperfusion-induced elevation of left ventricular end-diastolic pressure observed in untreated hearts was significantly reduced by in vitro exposure to the lowest concentrations of EGb 761, by ginkgolide A, and to a lesser extent by ginkgolide B, or by prior oral treatment with CP 205. Post-ischemic functional recovery.was significantly improved by in vivo administration of CP 205, by perfusion with 5 microg/ml of EGb 761 or with both terpenoids pared to untreated group but in vitro CP 205 was not effective. ESR analyses revealed that DMPO-OH (the DMPO/hydroxyl radical spin-adduct) concentrations in coronary effluents were markedly decreased by all treatments, except for the lowest concentration of ginkgolide B. Perfusing 5 microg/ml EGb 761 resulted in a better inhibition of baseline DMPO-OH concentration than 5 microg/ml CP 205 (-70 % and -48 % vs. control, respectively), indicating that both terpenoid and flavonoid constituents of EGb 761 are required to produce this effect. CP 205 was significantly more efficient in reducing DMPO-OH concentration when administered in vivo than when applied in vitro, indicating that the antioxidant effect of flavonoid metabolites (formed in vivo) is superior to that of intact flavonol glycosides (present in vitro). Collectively, these findings provide the first evidence that part of the cardioprotection afforded by EGb 761 is due to a specific action of its terpenoid constituents and that this effect involves a mechanism independent of direct free radical-scavenging. Thus, the terpenoid constituents of EGb 761 and the flavonoid metabolites that are formed after in vivo administration of the extract act in plementary manner to protect against myocardial ischemia-reperfusion injury. |
11099164 | Species-dependent changes in mechano-energetics of isolated cardiac muscle during hypoxia. | The present study investigates the mechanical and energetic changes induced by hypoxia in isolated cardiac muscles of different species characterized by different myosin isoforms. Classic mechanical parameters of contraction and energetic parameters derived from the tension-velocity relationship were studied in rat and guinea pig left ventricular papillary muscles and in frog ventricular strips before and after 15 min hypoxia (n = 8 in each group). The isomyosin pattern is predominantly V1 with high ATPase activity in rat and V3 with low ATPase activity in guinea pig and frog heart ventricles. At baseline, cardiac mechanical performance was greater in rat than in guinea pig and frog muscle, but the economy of tension generation did not differ significantly between the three species. Hypoxia significantly decreased myocardial mechanical performance in all three groups. Mechanical impairment was more marked in rat than in the other two species and was intermediate in guinea pig. The energetic consequences of hypoxia differed according to species and in a different manner from the mechanical parameters. Hypoxia decreased the economy of tension generation in rat heart, in contrast to no change in guinea pig and frog muscle. These results suggest that in terms of mechano-energetic properties, cardiac muscles with V1 isomyosin were more sensitive to hypoxia than those containing V3 isomyosin. |
11099165 | Recovery from sarafotoxin-b induced cardiopathological effects in mice following low energy laser irradiation. | Low energy laser irradiation has been shown to accelerate various biological processes, including regeneration of injured tissues. In the present work we studied the effect of low energy laser irradiation on ischemic mice hearts, following administration of sarafotoxin-b, a powerful vasoconstrictor peptide of the endothelin/sarafotoxin family. |
11099166 | Inhibition of protein phosphatase 1 induces apoptosis in neonatal rat cardiac myocytes: role of adrenergic receptor stimulation. | The mechanisms that regulate cardiac myocyte apoptosis are not well understood. To study the role of protein phosphatase 1 (PP1) and 2A (PP2A) in apoptosis, we exposed cultured neonatal rat cardiac myocytes to the phosphatase inhibitor okadaic acid (OA). Exposure (18 h) to 100 nM OA (a concentration which inhibits both PP1 and PP2A) decreased the number of adherent cells, caused genomic DNA fragmentation, and increased the percentage of apoptotic cells. These effects did not occur at a lower concentration of OA (1 nM) which is relatively specific for PP2A. Stimulation of alpha1- or beta-adrenergic receptors with norepinephrine (NE) in the presence of propranolol or prazosin partially blocked OA-induced apoptosis as measured by flow cytometry. Likewise, stimulation of adenylyl cyclase with forskolin reduced OA-induced apoptosis. Conversely, inhibition of protein kinase A with H89 or protein kinase C with chelerethrine potentiated OA-induced apoptosis. OA increased caspase-3 activity, and this effect was reduced by NE. Thus, inhibition of PP1 stimulates apoptosis in NRVM and stimulation of adrenergic receptors protects against OA-induced apoptosis. |
11099167 | Reduction in myocardial apoptosis associated with overexpression of heat shock protein 70. | It is reported that ischemia-reperfusion induces apoptotic cell death in myocardium. It is also demonstrated that heat shock protein 70 (HSP70) enhances myocardial tolerance. Therefore, it is hypothesized that HSP70 may play a role in the attenuation of myocardial apoptosis. To elucidate this goal, HSP70-overexpressing and control-transfected rat hearts were prepared using gene transfection by intra-coronary infusion of the hemagglutinating virus of Japan-liposome. In vivo experiment Hearts of both groups were subjected to global ischemia, followed by reperfusion in situ. Shorter recovery time to spontaneous beating (HSP70-transfected vs. control-transfected; 46.7+/-4.6 vs. 67.5+/-7.0 s, p = 0.033) and lower serum CPK levels (415+/-27 vs. 533+/-36 IU, p = 0.027) were observed in the HSP70-transfected group. The HSP70-transfected group also showed a lower percentage of cardiac myocytes positively stained by nick end labeling after ischemia-reperfusion (17.5+/-4.9 vs. 40.0+/-5.1%, p = 0.010). In vitro experiment Cardiac myocytes isolated from the hearts of both groups (prepared separately from the in vivo experiment) were subjected to hypoxia-reoxygenation. Flow cytometry was used to identify the cells that showed sub-G1 DNA content as apoptotic cells. Apoptotic cells as a percentage of viable cells increased more in the control-transfected group after hypoxia-reoxygenation (13.0+/-0.77 vs. 21.9+/-1.18%, p<0.0001). In conclusion, we demonstrated that apoptosis after ischemia-reperfusion was decreased in the HSP70-overexpressing heart in vivo and in vitro, leading to the suggestion that HSP70 could be associated with the reduction in myocardial apoptosis. |
11099168 | Influence of the angiotensin II AT1 receptor antagonist irbesartan on ischemia/reperfusion injury in the dog heart. | The aim of the present study was to investigate whether the non-peptide angiotensin II type 1 (AT1) receptor antagonist irbesartan (SR 47436, BMS 186295, 2-n-butyl-3 [2'-(1H-tetrazol-5-yl)-biphenyl-4-yl)methyl]-1,3-diaza-spiro [4,4]non-1-en-4-one) has myocardial protective effects during regional myocardial ischemia/reperfusion in vivo. Eighteen anesthetized open-chest dogs were instrumented for measurement of left ventricular and aortic pressure (tip manometer and pressure transducer, respectively), and coronary flow (ultrasonic flowprobes). Regional myocardial function was assessed by Doppler displacement transducers as systolic wall thickening (sWT) in the antero-apical and the postero-basal wall. The animals underwent 1 h of left anterior descending coronary artery (LAD) occlusion and subsequent reperfusion for 3 hours. Irbesartan (10 mg kg(-1), n = 9) or the vehicle (KOH, control, n = 9) was injected intravenously 30 min before LAD occlusion. Regional myocardial blood flow (RMBF) was measured after irbesartan injection and at 30 min LAD occlusion using colored microspheres. Infarct size was determined by triphenyltetrazolium chloride staining after 3 h of reperfusion. There was no recovery of sWT in the LAD perfused area in both groups at the end of the experiments (systolic bulging, -15.1+/-6.1% of baseline (irbesartan) vs. -12.3+/-3.0% (control), mean+/-SEM). Irbesartan led to an increase in RMBF in normal myocardium (2.47+/-0.40 vs. 1.35+/-0.28 ml min(-1) g(-1), p<0.05), and also to an increase in collateral blood flow to the ischemic area (0.27+/-0.04 vs. 0.17+/-0.02 ml min(-1) g(-1), P = <0.05). Infarct size (percent of area at risk) was 24.8+/-3.2 % in the treatment pared with 26.9+/-4.8% in the control group (P = 0.72). These results indicate that a blockade of angiotensin II AT1 receptors with irbesartan before coronary artery occlusion led to an increase in RMBF, but did not result in a significant reduction of myocardial infarct size. |
11099169 | Level of circulating phospholipase A2 in prediction of the prognosis of patients with suspected myocardial infarction. | Atherosclerotic lesions result from inflammatory-proliferative responses of the endothelium and smooth muscle of the arterial wall. Poor prognosis of acute myocardial infarction (AMI) patients has been associated with elevated levels of acute phase proteins including C-reactive protein. We investigated the significance of circulating phospholipase A2 in the long-term prognosis of suspected AMI patients. |
11099170 | Delayed attenuation of myocardial ischemia with repeated exercise in subjects with stable angina: a possible model for the second window of protection? | A delayed myocardial protection extends between 24 and 96 h after ischemic preconditioning in animals. To test for this phenomenon in humans, subjects with stable angina were subjected to exercise test-induced myocardial ischemia and the effect of this "preconditioning" ischemic insult on the exercise-induced myocardial ischemia with the re-exercise after 24-96 hours was studied. |
11099172 | Correlation between the effects of a cationic peptide on the hydration and fluidity of anionic lipid bilayers: a comparative study with sodium ions and cholesterol. | The cationic tridecapeptide alpha-melanocyte stimulating hormone (alpha-MSH) is known to interact with anionic vesicles of 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG), partially penetrating the lipid membrane. In the lipid liquid crystal phase, phospholipid derivatives spin labeled at the different C-atoms along the acyl chain, show that the peptide increases the bilayer packing at all depths. Parallel to that, there is an increase in the probe's isotropic hyperfine splittings, indicating that the peptide significantly decreases the membrane hydrophobic barrier. Accordingly, it is suggested that the increase in membrane packing yielded by alpha-MSH is partly due to a greater level of interchain hydration. This result pared to the increase in packing and decrease in polarity yielded by cholesterol, and the absence of structural or polar alterations with Na+. The latter result shows that the peptide effect is not related to an increase of positive charges at the anionic vesicle surface. Alterations on the lipid bilayer polar profile measured by the nitroxide hyperfine splitting ponent in frozen samples are shown to be different from those obtained at room temperature. However, it is shown here that a certain correlation can be drawn between the increase in polarity measured in frozen samples and the packing effect caused by the different molecules in the lipid gel phase. |
11099171 | Magnetocardiographic QT dispersion during cardiovascular autonomic function tests. | QT dispersion is considered to reflect nonhomogeneity of ventricular repolarization. The autonomic nervous system modulates QT interval duration, but the effect may not be spatially homogenous. Magnetocardiography (MCG) registers the weak magnetic fields generated by myocardial electric currents with high localizing accuracy. We studied the effects of rapid cardiovascular autonomic nervous adjustment on QT dispersion in MCG. Ten healthy male volunteers were monitored during deep breathing, the Valsalva maneuver, sustained handgrip, hyperventilation, the cold pressor test and mental stress. 67 MCG channels and 12 ECG leads were recorded simultaneously. puter algorithm was used for QT interval measurements. QT dispersion was defined as maximum - minimum or standard deviation of the QTpeak and QTend intervals. In MCG the QT(end) dispersion increased during deep pared with deep expiration (96+/-19 ms v. 73+/-27 ms, p = 0.05). Magnetic QT dispersion tended to increase during the bradycardia phase of the Valsalva maneuver, but the change was obvious only for QT(end) (55+/-26 ms v. 76+/-29 ms, p<0.05). Other tests had no significant effect on QT dispersion, not even the cold pressor test, although it causes strong sympathetic activation. Magnetic and electric QT(peak) and QT(end) intervals correlated closely (r = 0.93 and 0.91), whereas the QT dispersion measures showed no correlation. In conclusion, magnetic QT dispersion is not modified by rapid changes in autonomic tone, but maneuvers involving deep respiratory efforts and changes in ventricular loading affect QT dispersion measurements. |
11099173 | Conformational transition of DNA in electroreduction studied by in situ UV and CD thin layer spectroelectrochemistry. | Electrochemically induced three conformational transitions of calf thymus DNA from B10.4 to Z10.2-DNA and from B10.2 to B10.4 and to C-DNA in 10 mM phosphate buffer solution (pH 7.21) at glassy carbon electrode are found and studied by in situ circular dichroism (CD) thin layer spectroelectrochemistry with singular value position least square (SVDLS) analysis. It indicates that the so-called B10.2 form and the C-form of DNA may posed of B10.4 and left-A DNA and of B10.4 and right-A DNA, respectively. The irreversible electrochemical reduction of adenine and cytosine groups in the DNA molecule is studied by UV-Vis spectroelectrochemistry. Some electrochemical parameters alpha n = 0.17, E0' = -0.70 V (vs. Ag/AgCl), and the standard heterogeneous electron transfer rate constant, k0 = 1.8 x 10(-5) cm s(-1), are obtained by double logarithmic analysis and non-linear regression. |
11099174 | A spectroscopic analysis of thermal stability of the Chromobacterium viscosum lipase. | The thermal stability of the lipase from Chromobacterium viscosum was assessed by deactivation (loss of activity), fluorescence, circular dichroism (CD) and static light scattering (SLS) measurements. Lipase fluorescence emission is dominated by the tryptophyl contribution. An increase in the tyrosyl contribution from 2 to 16% was only observed upon prolonged incubation at 60 degrees C. The effect of temperature on the tryptophyl quantum yield was studied and two activation energies were calculated. Tryptophan residues in the native structure have an activation energy of 1.9 kcal mol(-1) for temperature-dependent non-radiative deactivation of the excited state. A structural change occurs at approximately 66.7 degrees C and the activation energy increases to 10.2 kcal mol(-1). This structural change is not characterized by tryptophan exposure on the surface of the protein. The deactivation and the evolution of structural changes with time after lipase incubation at 60 degrees C were assessed by fluorescence, CD and SLS measurements. CD spectra show that both secondary and tertiary structures remain native-like after incubation at 60 degrees C in spite of the fluorescence changes observed (red-shift from 330 to 336 nm on the trytophyl emission). SLS measurements together with the CD data show that deactivation may be due to protein association between native molecules. Deactivation and the decrease on the fraction of non-associated native lipase evaluated by changes in fluorescence intensity with time, show apparent first order kinetics. According to the rate constants, fluorescence changes precede deactivation pointing to an underestimation of the deactivation. Reactivation upon dilution during the activity assay and substrate-induced reactivation due to lipase interfacial adsorption are possible causes for this underestimation. |
11099175 | A chemical flow system mimics waves of gene expression during segmentation. | The early vertebrate developmental process of somitogenesis involves bands of gene expression that form periodically at the posterior end of the presomitic mesoderm (PSM) and traverse it with decreasing width and velocity. We have constructed a chemical flow system that, based on the novel flow-distributed oscillator (FDO) mechanism of wave pattern formation, reproduces key physical features of the PSM and observe concentration waves having similar spatio-temporal behavior. This suggests that the gene expression waves can be understood qualitatively in terms of phase dynamics in an open flow of a self-oscillating medium and that chemical flow systems can be used to mimic and model biological pattern formation during axial growth. In fact, expressions for wavelength and wave velocity derived from phase dynamics are found to be in quantitative agreement with measurements from both the biological and the chemical systems. This indicates that they, despite their significant differences, mon dynamics. |
11099177 | Step-wise formation of helical structure and side-chain packing in a peptide from scorpion neurotoxin support hierarchic model of protein folding. | The mechanism of protein folding has been the subject of extensive investigation during the last decade, both because of its academic challenge and because of its relation to many diseases which are known to occur due to misfolding of proteins. In this context, we report here a systematic investigation on the step-wise formation of a helical structure by the addition of hexafluoroacetone, in a 14-residue peptide derived from a part of the scorpion neurotoxin protein. The NMR and circular dichroism results indicate that the peptide has an inherent propensity for helix formation and this is limited to the internal few residues in aqueous solution. With the addition of the fluorosolvent, the helical content progressively increases and spans the whole sequence. This is panied by itant packing of the side chains. These results provide support to the so-called hierarchic model of protein folding which dictates that the local sequence determines the secondary structures in the protein and the side chains play an important role in this process. |
11099176 | pH-sensitive liposomes as a carrier for oligonucleotides: a physico-chemical study of the interaction between DOPE and a 15-mer oligonucleotide in excess water. | The cytoplasmic delivery of drugs encapsulated into pH-sensitive liposomes is under the control of a lamellar-to-hexagonal transition. In a previous study, under anhydrous conditions, oligonucleotides (ODN) encapsulated in pH-sensitive posed of dioleoylphosphatidylethanolamine (DOPE)/oleic acid (OA)/cholesterol (CHOL) were shown to modify the phase behaviour of DOPE. In the present study, the lipid/ODN interactions were evaluated in fully hydrated samples by surface tension measurements, differential scanning calorimetry, X-ray diffraction and turbidimetry. Concerning the lipids, it was shown that OA provoked a disorganisation of DOPE lamellar phases and led to plete disappearance of hexagonal transition along with heating. The addition of CHOL further decreased the lipid packing in the bilayers. Concerning ODN, these molecules provoked an increase in the surface pressure of a DOPE/OA/CHOL monolayer, indicating the existence of molecular interactions with the lipids. At a supramolecular level, ODN induced a more ordered organisation of DOPE molecules in the lamellar and hexagonal phases, pletely abolished the disorganisational effect of OA and CHOL. |
11099179 | Electromigration of polyion homopolymers across biomembranes: a biophysical model. | The analysis of polyion transmembrane translocation was performed using membrane electrical equivalent circuit. The dependence of polyion flux across membranes on time, membrane electrical conductance, membrane electrical capacitance, degree of polymerization, water solution conductance and applied transmembrane potential is discussed. The changes in polyion flux were up to 88% after 1 ms. Both the increase of polyion chain length and the decrease of membrane conductance resulted in the diminution of this effect. Inversion of flux direction was observed as a result of external potential changes. Reversal curves, representing the values of considered parameters for zero-flux were also shown. The replacement of a polyanion by a polycation of the same chain length resulted in the same shape of the surface plot but with opposite orientation. The analysis describes the effect of transmembrane potential on the translocation rate of polyanionic polysialic acid and polynucleotides, and polycationic peptides across membranes. |
11099178 | Binding of human immunodeficiency virus type 1 nucleocapsid protein to psi-RNA-SL3. | The interaction of the nucleocapsid protein NCp7, from the pNL4-3 isolate of HIV-1, with psi-RNA-SL3, with the sequence 5'-GGACUAGCGGAGGCUAGUCC, was studied using non-denaturing gel electrophoresis. Two kinds of experiments were performed, using buffered solutions of radiolabeled RNA and unlabeled protein. In the 'dilution' experiments, the total RNA concentration, RT, was varied for a series of solutions, but kept equal to the total protein concentration, PT, In the 'titration' experiments, solutions having RT constant but with varying PT were analyzed. The solutions were electrophoresed and the autoradiographic spot intensities, proportional to the amounts of the different species present, were measured. The intensities were fit to a number of equilibrium models, differing in species stoichiometries, by finding the best values of the binding constants. It was shown that NCp7 protein and SL3 bine to form at least plexes. When PT is below approximately 10 microM, plex that contains two RNAs and one protein forms. Increasing PT to approximately 100 microM causes the plex to oligomerize, forming a species having eight RNAs and four proteins. For the dilution experiments, run at 5 degrees C at an ionic strength of 31 mM, we found K1 for the plex is approximately 10(11) M(-2) and K2 for the plex is approximately 10(16) M(-3). The titration experiments returned K1 approximately 10(7) M(-2) (poorly determined) and K2 approximately 10(19) M(-3). The analysis plicated by the loss of RNA at higher protein concentrations, due to formation of an insoluble species containing both RNA and protein, which does not enter the gel. Correcting for this changes the calculated values of equilibrium constants, but not the molecularities determined by our analysis. The observation that a plex can oligomerize to form a larger species is consistent with the fact that NCp7 organizes and condenses the genome in the virus particle. |
11099180 | Voltammetric and spectroscopic studies on methyl green and cationic lipid bound to calf thymus DNA. | DNA interaction with cationic lipids promises to be a versatile and effective synthetic transfection agent. This paper presents the study on binding of a simple artificial cationic lipid, cetyltrimethylammonium bromide (CTAB), to calf thymus DNA (CT DNA) prior to the condensation process, taking methyl green (MG) as a probe. The results show that the CTAB binds to DNA through electrostatic interaction forming a plex, thus changing the micro-environment of duplex of DNA, so the binding state of MG and DNA is changed, and plex CTAB-CT DNA-MG is formed. This fact suggests a new way to mediate the conformation of molecular assemblies of DNA and lipids. |
11099181 | Analysis of negative cooperativity for glutamate dehydrogenase. | The empirical equation, which describes negative cooperativity in the enzyme kinetics, has been proposed. The equation is obtained from the Michaelis-Menten equation where the Michaelis constant is replaced by the effective Michaelis constant, which is a linear function of the v/Vmax ratio (v is the rate of the enzymatic reaction and Vmax is the limiting value of v at saturating concentrations of substrate). The equation allows the limiting values of the Michaelis constant at v/Vmax --> 0 and V/Vmax --> 1 to be estimated, K0 and Klim, respectively. The Klim/K0 ratio is considered as a quantitative characteristic of negative cooperativity. The applicability of the equation has been demonstrated for the kinetic data obtained for glutamate dehydrogenases from various sources (negative kinetic cooperativity for coenzyme). The negative cooperativity for the functions of saturation of protein by ligand is also analyzed. The data on binding of spin-labeled NAD, NADH, and NADPH by beef liver glutamate dehydrogenase are used as examples. |
11099183 | Interaction of benzocaine with model membranes. | We measured the absorption properties, water solubility and partition coefficients (P) between n-octanol, egg phosphatidylcholine (EPC) liposomes and erythrocyte ghosts/water for benzocaine (BZC), an ester-type always uncharged local anesthetic. The interaction of BZC with EPC liposomes was followed using Electron Paramagnetic Resonance, with spin labels at different positions in the acyl chain (5, 7, 12, 16-doxylstearic acid methyl ester). Changes in lipid organization upon BZC addition allowed the determination of P values, without phase separation. The effect of BZC in decreasing membrane organization (maximum of 11.6% at approx. 0.8:1 BZC:EPC) pared to those caused by the local anesthetics tetracaine and lidocaine. Hemolytic tests revealed a biphasic (protective/inductive) concentration-dependent hemolytic effect for BZC upon rat erythrocytes, with an effective BZC:lipid molar ratio in the membrane for protection (RePROT), onset of hemolysis (ReSAT) and 100% membrane solubilization (ReSOL) of 1.0:1, 1.1:1 and 1.3:1, respectively. The results presented here reinforce the importance of considering hydrophobic interactions in the interpretation of the effects of anesthetics on membranes. |
11099182 | Dynamics of compact denatured states of glutaminyl-tRNA synthetase probed by bis-ANS binding kinetics. | Bis-ANS binds to native glutaminyl-tRNA synthetase (GlnRS) with a fast and a slow phase. The rate constant of the slow phase is independent of bis-ANS concentration suggesting a slow conformational change in the pathway of bis-ANS binding. Aging of GlnRS causes a large decrease of the slow phase amplitude with itant increase of the fast phase amplitude. Several other large, multi-domain proteins show similar patterns upon aging. The near UV-CD spectra of the native and the aged GlnRS remain similar. Significant changes in far UV-CD, acrylamide quenching and sulfhydryl reactivity, are seen upon aging, suggesting disruptions in native interactions. Refolding of GlnRS from the urea-denatured state rapidly produces a state that is very similar to the equilibrium molten globule state. Bis-ANS binds to the molten globule state with kinetics similar to that of the aged state and unlike that of the native state. This suggests that the slow binding phase of bis-ANS, seen in native proteins, originate from relatively high energy barriers between the native and the more open states. Thus bis-ANS can be used as a powerful probe for large amplitude, low-frequency motions of proteins. |
11099184 | Involvement of two groups in reversal of the bathochromic shift of pharaonis phoborhodopsin by chloride at low pH. | Pharaonis phoborhodopsin (ppR; or pharaonis sensory rhodopsin II, psRII) is a photophobic receptor of the halobacterium Natronobacterium pharaonis. Its lambdamax is at 496 nm, but upon acidification in the absence of chloride, lambdamax shifted to 522 nm. This bathochromic shift is thought to be caused by the protonation of Asp75, which corresponds to Asp85 of bacteriorhodopsin (bR). The D75N mutant, in which Asp75 was replaced by Asn, had its lambdamax at approximately 520 nm, supporting this mechanism for the bathochromic shift. A titration of the shift yielded a pKa of 3.5 for Asp75. In the presence of chloride, the spectral shifts were different: with a decrease in pH, a bathochromic shift was first observed, followed by a hypsochromic shift on further acidification. This was interpreted as: the disappearance of a negative charge by the protonation of Asp75 pensated by the binding of chloride, but it is worthy to note that the binding requires the protonation of another proton-associable group other than Asp75. This is supported by the observation that in the presence of chloride, upon acidification, the lambdamax of D75N even showed a blue shift, showing that the protonation of a proton-associable group (pKa = 1.2) leads to the chloride binding that gives rise to a blue shift. |
11099187 | Adaptive portal CT reconstruction: a simulation study. | In radiotherapy, radiation treatment beams contain valuable information for patient setup verification. These beams may be used for portal CT reconstruction. However, direct use of the beam data for reconstruction may yield inadequate CT images simply because these beams cover only a part of the patient body. In this study, we use the treatment beams in addition to a set of regular CT projection beams to reconstruct a locally enhanced portal CT image. This approach is called adaptive portal CT reconstruction. puter simulation demonstrated the advantages of the approach. The image reconstruction was carried out by the multilevel scheme algebraic reconstruction technique. Results indicated that the image quality of adaptive portal CT reconstruction is equivalent to that obtained from a full set of projections. This proposed technique should be not only valuable for three-dimensional radiotherapy verification, but also applicable to diagnostic CT imaging. |
11099186 | Performance of a fluorescent screen and CCD camera as a two-dimensional dosimetry system for dynamic treatment techniques. | A two-dimensionally position sensitive dosimetry system has been tested for different dosimetric applications in a radiation therapy facility with a scanning proton beam. The system consists of a scintillating (fluorescent) screen, mounted at the beam-exit side of a phantom and it is observed by a charge coupled device (CCD) camera. The observed light distribution at the screen is equivalent to the two-dimensional (2D)-dose distribution at the screen position. It has been found that the dosimetric properties of the system, measured in a scanning proton beam, are equal to those measured in a proton beam broadened by a scattering system. Measurements of the transversal dose distribution of a single pencil beam are consistent with dose measurements as well as with dose calculations in clinically relevant fields made with multiple pencil beams. Measurements of inhomogeneous dose distributions have shown to be of sufficient accuracy to be suitable for the verification of dose calculation algorithms. The good sensitivity and sub-mm spatial resolution of the system allows for the detection of deviations of a few percent in dose from the expected (intended or calculated) dose distribution. Its dosimetric properties and the immediate availability of the data make this device a useful tool in the quality control of scanning proton beams. |
11099188 | Dependence of linac output on the switch rate of an intensity-modulated tomotherapy collimator. | The electro-mechanical, multivane intensity modulated collimator ("MIMiC") slit collimator with 40 vanes has been applied in the delivery of inversely planned sequential tomotherapy to over 4,000 patients. The collimator is binary in that each vane switches between fully open or closed status. Resulting beamlet patterns provide the intensity distributions imparting dose to the patient. The bouncing and damping of vanes at the two ends of their travel cause transient dose perturbations near and at the borders of the treatment field. These perturbations are not explicitly modeled by the planning system. Clinical beamlet profiles and output factors may then differ from those in the planning system and as a function of the vane switch period. A mechanical model of vane switching was developed to describe this dependency. Dose output and distribution of seven simple vane patterns with different switch times were measured with ionization chambers and radiographic films in polystyrene and anthropomorphic phantoms. Linac output dependence on switch time relative to vane open time was determined for four intensity modulated radiotherapy (IMRT) patients from measurements of an ionization chamber embedded in a cylindrical polystyrene phantom. Results demonstrate output dependence on switch time and, accordingly, on the servo mechanism for monitor units, arc length, dose rate, and gantry speed. In conclusion, the output dependence borders on clinical significance-improvements to collimator, dose missioning, and quality assurance (QA) are suggested. |
11099189 | A monitor unit verification calculation in intensity modulated radiotherapy as a dosimetry quality assurance. | In standard teletherapy, a treatment plan is generated with the aid of a treatment planning system, but it mon to perform an independent monitor unit verification calculation (MUVC). In exact analogy, we propose and demonstrate that a simple and accurate MUVC in intensity modulated radiotherapy (IMRT) is possible. We introduce the concept of modified Clarkson integration (MCI). In MCI, we exploit the rotational symmetry of scattering to simplify the dose calculation. For dose calculation along a central axis (CAX), we first replace the incident IMRT fluence by an azimuthally averaged fluence. Second, the Clarkson integration is carried over annular sectors instead of over pie sectors. We wrote puter code, implementing the MCI technique, in order to perform a MUVC for IMRT purposes. We applied the code to IMRT plans generated by CORVUS. The input to the code consists of CORVUS plan data (e.g., DMLC files, jaw settings, MU for each IMRT field, depth to isocenter for each IMRT field), and the output is dose contribution by individual IMRTs field to the isocenter. The code uses measured beam data for Sc, Sp, TPR, (D/MU)ref and includes effects from multileaf collimator transmission, and radiation field offset. On a 266 MHz puter, the code takes less than 15 to calculate a dose. The doses calculated with the MCI algorithm agreed within +/-3% with the doses calculated by CORVUS, which uses a 1 cm x 1 cm pencil beam in dose calculation. In the present version of MCI, skin contour variations and inhomogeneities were neglected. |
11099190 | A method for determining multileaf collimator transmission and scatter for dynamic intensity modulated radiotherapy. | The main purpose of this work is to demonstrate a practical means of determining the leaf transmission and scatter characteristics of a multileaf collimator (MLC) pertinent to missioning of dynamic intensity modulated radiotherapy, especially for the sweeping window technique. The data are necessary for the conversion of intensity distributions produced by intensity-modulated radiotherapy optimization systems into trajectories of MLC leaves for dynamic delivery. Measurements are described for two, tungsten alloy MLCs: a Mark II 80-leaf MLC on a Varian 2100C accelerator and a Millenium 120-leaf MLC on a Varian 2100EX accelerator. MLC leakage was measured by film for a series of field sizes. Measured MLC leakage was 1.68% for a 10 x 10 cm2 field for both 6 and 18 MV for the 80-leaf MLC. For the 6 MV field, the 1.68% leakage consisted of 1.48% direct transmission and 0.20% leaf scatter. Direct transmission through the 80-leaf MLC, including the rounded leaf tip, was calculated analytically taking into account the detailed leaf geometry and a Monte Carlo-generated energy spectrum of the accelerator. The integrated fluence under the leaf tip was equivalent to an inward shift of 0.06 cm of a hypothetical leaf with a flat, focused tip. Monte Carlo calculations of the dose to phantom beyond a closed 80-leaf MLC showed excellent agreement with the analytic results. The transmission depends on the density of the MLC alloy, which may differ among individual MLCs. Thus, it is important to measure the transmission of any particular MLC. Calculated doses for a series of uniform fields produced by dynamic sweeping windows of various widths agree with measurements within 2%. |
11099191 | A design for a dual assembly multileaf collimator. | A multileaf collimator for radiation therapy has been designed that splits each leaf bank into two vertically displaced levels with each level consisting of alternate leaves and leaf spaces. The leaves in the upper level shield the spaces in the lower level. Each level can move laterally, in the direction perpendicular to leaf motion by one leaf width. Following lateral movement of one level, the leaves align with the other level and radiation is transmitted through the collimator as multiple slit fields in a grid pattern. This transmission can be used to form an image of the external anatomy and would enable double-exposure portal images to be acquired much more rapidly than at present. These could potentially be acquired during the treatment delivery. The radiation profiles transmitted for image formation through the collimator design were investigated. Individual and grid pattern slit field profiles formed by tungsten and lead alloy collimators were measured with varying slit width, source-collimator distance, collimator-detector distance, and collimation thickness. The slit width was found to have the major influence on the transmitted profiles. As the slit width decreases the profiles e broader than the geometric slit projection resulting in increasing overlap of adjacent profiles. The overlap results in a modulated image of the external anatomy for small slit widths, rather than a sampled or "grid" image for larger widths. The shielding of this design was found to be adequate provided the leaf faces of the adjacent vertically displaced leaves are at least aligned, therefore an overlap or tongue and groove is not required. |
11099192 | Comparison of measured and Monte Carlo calculated dose distributions from the NRC linac. | We have benchmarked photon beam simulations with the EGS4 user code BEAM [Rogers et al., Med. Phys. 22, 503-524 (1995)] paring calculated and measured relative ionization distributions in water from the 10 and 20 MV photon beams of the NRC linac. Unlike previous calculations, the incident electron energy is known independently to 1%, the entire extra-focal radiation is simulated, and electron contamination is accounted for. The full Monte Carlo simulation of the linac includes the electron exit window, target, flattening filter, monitor chambers, collimators, as well as the PMMA walls of the water phantom. Dose distributions are calculated using a modified version of the EGS4 user code DOSXYZ which additionally allows scoring of average energy and energy fluence in the phantom. Dose is converted to ionization by accounting for the (L/rho)water(air) variation in the phantom, calculated in an identical geometry for the realistic beams using a new EGS4 user code, SPRXYZ. The variation of (L/rho)water(air) with depth is a 1.25% correction at 10 MV and a 2% correction at 20 MV. At both energies, the calculated and the measured values of ionization on the central axis in the buildup region agree within 1% of maximum ionization relative to the ionization at 10 cm depth. The agreement is well within statistics elsewhere. The electron contamination contributes 0.35(+/- 0.02) to 1.37(+/- 0.03)% of the maximum dose in the buildup region at 10 MV and 0.26(+/- 0.03) to 3.14(+/- 0.07)% of the maximum dose at 20 MV. The penumbrae at 3 depths in each beam (in g/cm2), 1.99 (dmax, 10 MV only), 3.29 (dmax, 20 MV only), 9.79 and 19.79, agree with ionization chamber measurements to better than 1 mm. Possible causes for the discrepancy between calculations and measurements are analyzed and discussed in detail. |
11099193 | Comparison of dosimetric characteristics of Siemens virtual and physical wedges. | Dosimetric properties of Virtual Wedge (VW) and physical wedge (PW) in 6 and 23 MV photon beams from a Siemens Primus linear accelerator, including wedge factors, depth doses, dose profiles, peripheral doses and surface doses, pared. While there is a great difference in absolute values of wedge factors, VW factors (VWFs) and PW factors (PWFs) have a similar trend as a function of field size. PWFs have a stronger depth dependence than VWF due to beam hardening in PW fields. VW dose profiles in the wedge direction, in general, match very well with PW, except in the toe area of large wedge angles with large field sizes. Dose profiles in the nonwedge direction show a significant reduction in PW fields due to off-axis beam softening and oblique filtration. PW fields have significantly higher peripheral doses than open and VW fields. VW fields have similar surface doses as the open fields while PW fields have lower surface doses. Surface doses for both VW and PW increase with field size and slightly with wedge angle. For VW fields with wedge angles 45 degrees and less, the initial gap up to 3 cm is dosimetrically acceptable pared to dose profiles of PW. VW fields in general use less monitor units than PW fields. |
11099194 | Dosimetric characteristics of a new 125I brachytherapy source. | 125I brachytherapy sources are being used for interstitial implants in tumor sites such as the prostate. Recently, a new 125I source has been introduced, which has a design different from that of other sources presently on the market. Dosimetric characteristics of this source, including dose rate constant, radial dose function, and anisotropy function, were determined experimentally following the AAPM Task Group 43 mendations. The characteristics were related to the 1999 NIST calibration assigned to this source [SK,99std]. Measurements were performed in a solid water phantom using LiF thermoluminescent dosimeters. For these measurements, slabs of solid water phantom material were machined to modate the source and LiF TLD chips of dimensions (3.1 x 3.1 x 0.8 mm3) and (1.0 x 1.0 x 1.0 mm3). The TLD chips were surrounded by at least 10 cm of solid water phantom material to provide full scattering conditions. The results indicated a dose rate constant, lambda, of 0.88 +/- 0.07cGyh(-1)U(-1) for the new 1251 source pared to 0.98 and 1.04 cGy h(-1)U(-1) for the ed/Amersham model 6711 and 6702 seeds, respectively. Per TG-43, the values reported here represent the dose absorbed by water at 1 cm from the source in a water medium. The radial dose function, g(r), of the new 125I source was measured at distances ranging from 0.5 to 10 cm. The anisotropy function, F(r,theta), of the new 125I source was measured at distances of 2 and 5 cm from the source center. Calculations of anisotropy and radial dose function were also made using a Monte Carlo code. These calculations were made for both solid water and liquid water, the former to validate the Monte Carlo code and the latter to provide results in liquid water for clinical use. All pared favorably with those from the ed/Amersham models 6711 and 6702 sources. |
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