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8041291 | Effect of beta-lactamase on minimum inhibitory concentrations of methicillin in methicillin-resistant Staphylococcus aureus. | A study was undertaken to determine whether the production of penicillin-binding protein-2' (PBP-2') and the production of beta-lactamase were related to the minimum inhibitory concentrations of methicillin (DMPPC) in various strains of methicillin-resistant Staphylococcus aureus. The amount of PBP-2' produced by the low-level resistant strain L20A was small and the strain became resistant to DMPPC as a result of inactivation of DMPPC by beta-lactamase. The largest amount of PBP-2' produced was in a moderately resistant strain L21A but the MIC was not high since the strain was not capable of producing beta-lactamase and the population of cells was heterogeneous. The amount of PBP-2' produced in the high-level resistant strain L457A was lower than that in strain L21A but the MIC was high as a result of the production of beta-lactamase. Production of PBP-2' was essential for resistance to methicillin but production of beta-lactamase had a major effect on the MIC. |
8041290 | Examination of the glycocalyx of four species of Staphylococcus by transmission electron microscopy and image analysis. | The coagulase-negative staphylococci have become important pathogens in human infections involving foreign bodies. The bacterial glycocalyx is a major mediator of attachment of these organisms to medical devices, but the glycocalyx is sometimes difficult to demonstrate. A combination of the techniques of transmission electron microscopy (TEM) and image analysis enabled investigators to reveal the glycocalyx which was previously indiscernible. Eight strains of coagulase-negative staphylococci, including Staphylococcus epidermidis, S. hominis, S. lugdunensis, and S. schleiferi subspecies schleiferi, were grown, treated with anti-staphylococcal serum to stabilize the glycocalyx, and examined by TEM. Image analysis of negatives was then used to enhance the visual images which showed far more glycocalyx than previously seen by TEM alone. |
8041278 | Hydroxylation and dealkylation reactions catalyzed by hemoglobin. | Red blood cells contain many enzymes that are akin to those that catalyze xenobiotic metabolism in liver and other tissues. An obvious exception is the cytochrome P-450 system that is found in virtually all other tissues. In vitro studies, however, have shown that hemoglobin can be a broad monooxygenase catalyst, exhibiting the properties of a monooxygenase enzyme. Thus, catalysis by Hb displays typical Michaelis-Menten kinetics, dependence on the native protein, coupling to NADPH-dependent flavoprotein reductases, and inhibition by carbon monoxide. The reconstituted system containing Hb along with P-450 reductase utilizes NADPH and O2 to catalyze typical monooxygenase reactions, including O- and N-demethylations as well as aromatic and aliphatic hydroxylations, and the catalytic cycle appears to mimic the typical P-450 mechanism. Turnover numbers for aniline hydroxylation are similar for Hb and P-450 reconstituted systems, whereas P-450 systems are more effective for other reactions. Catalysis by Hb seems to be restricted to the beta-heme sites of the tetramer, reflecting more facile substrate access. Overall the similarities and differences between Hb and P-450 provide an opportunity to examine the basis for their differential monooxygenase or peroxidase/peroxygenase activities in a comparative manner. Hb may be especially useful in delineating the early events in the respective reaction schemes, because it can be studied in various stable redox/ligand states, including the oxyferrous form. Similar hemoglobin-catalyzed oxidative biotransformations occur within intact erythrocytes, but apparent turnover numbers are much lower than those with the reconstituted Hb system, suggesting different mechanisms of catalysis. Although Hb-mediated oxidase activity in erythrocytes is low relative to other sites of xenobiotic metabolism, it may contribute to in situ activation of xenobiotics leading to oxidative stress, disruption of sulfhydryl homeostasis in the erythrocytes, covalent modification of Hb, and hemolysis. |
8041245 | Psychiatric manifestations of systemic lupus erythematosus: clinical features, symptoms, and signs of central nervous system activity in 43 patients. | Forty-three female inpatients with active systemic lupus erythematosus (SLE) were studied by a multidisciplinary team to answer the following research questions: 1) What are the features of the psychopathology in patients with active SLE? and 2) In these patients, what is the relationship between psychiatric disorders and symptoms and signs suggesting activity of SLE in the CNS? Our a priori hypothesis was that, in patients with active SLE, those with psychiatric manifestations would have more symptoms and signs of CNS activity than those without psychiatric manifestations. Psychiatric evaluation consisted of standardized psychiatric instruments and diagnostic criteria. The assessment of SLE systemic and central nervous system (CNS) activity consisted of rheumatologic, neurologic, and ophthalmologic evaluations; serum and cerebral spinal fluid (CSF) analysis; brain computerized tomography (CT); and electroencephalogram (EEG). Twenty-seven patients (63%) presented psychiatric symptoms (Psychiatric Group), and 16 (37%) patients presented no current psychiatric diagnosis (Nonpsychiatric Group). These groups were compared in terms of the above variables. Depressive syndrome was the most frequent diagnosis (44%) followed by delirium (7%) and dementia (5%). Psychiatric symptoms were associated with subjective cognitive impairment (85%) and neurologic abnormality (85%). Widened cortical sulci was the most frequent CT alteration and was equally common in both groups. No statistical difference was found between the 2 groups regarding their general clinical evaluation, serum and CSF exams, or EEG alterations. To determine whether the severity of psychiatric symptoms was related to CNS activity, we divided the 27 patients with psychiatric manifestations into 2 groups: the Major Group--18 patients with major psychopathology, and the Minor Group--9 patients with mild depressive syndromes.(ABSTRACT TRUNCATED AT 250 WORDS) |
8041244 | Hyperlipidemia in renal transplant recipients: natural history and response to treatment. | The lipid profiles of 192 patients with functioning renal transplants and their etiologic associations and response to therapy, in particular simvastatin, were assessed. Hypercholesterolemia was present in 71.3% of patients within 3 years following transplantation. There were independent associations of serum cholesterol with prednisone dosage (p < 0.05), renal function (p < 0.05), and smoking (p < 0.05) in the early posttransplant period (up to 3 months posttransplant). Those patients whose immunosuppression included cyclosporin had lower serum cholesterol levels than those receiving azathioprine and prednisone (p < 0.02). Plasma triglyceride levels reflected a marked interindividual variation, and no independent correlations were observed. The presence of diabetes mellitus, hypertension (or the use of antihypertensive agents), or the form or duration of prior dialysis did not independently influence the lipid profiles. During the study period 22 patients died, 54.5% due to vascular causes. Those who died of vascular causes had higher serum cholesterol levels than those who died of other causes, which reached statistical significance at 3 years posttransplant (7.74 +/- 0.4 versus 5.5 +/- 0.52 mmol/L; p < 0.02). Cholestyramine was introduced in 30 patients, only 2 of whom continued with therapy beyond 3 months. Simvastatin was used in 43 patients, 20 of whom were receiving cyclosporin, resulting in a mean reduction in serum cholesterol of 16.5% (p < 0.001) and in serum triglycerides of 21% (p < 0.05). No clinical or biochemical evidence of muscle, liver, or renal toxicity occurred in 15.4 +/- 0.9 months of follow-up. |
8041243 | Sepsis caused by Flavimonas oryzihabitans. | Previous reports of F. oryzihabitans sepsis involving central venous access devices reveal a relatively high rate of complications, including device removal, despite a course of broad-spectrum anti-microbials with compatible in vitro susceptibility results. In the present report of 22 cases of F. oryzihabitans sepsis treated at Memorial Sloan-Kettering Cancer Center from February 1986 through September 1993, the majority of CVAD-related infections with F. oryzihabitans were successfully treated with a 14-day course of antimicrobials with antipseudomonal activity, and removal of the device was usually not required. Factors that may complicate successful treatment of CVAD-related sepsis caused by F. oryzihabitans include polymicrobial infections and premature discontinuation of antibiotic therapy. |
8041242 | The current spectrum of Staphylococcus aureus infection in a tertiary care hospital. | Staphylococcus aureus remains a prominent cause of community- and hospital-acquired infection. This study reviewed 162 cases of S. aureus infection occurring in 120 adults who were hospitalized at a Veterans Affairs Medical Center and referred for consultation to the Infectious Disease Service. There were 37 cases of skin and soft tissue infection, 5 pyomyositis, 34 osteomyelitis, 13 septic arthritis, 19 pneumonia, 3 empyema, 5 pyelonephritis, 37 vascular infection, 3 epidural abscess, and 6 miscellaneous infections. Bacteremia was documented in 56 of 119 (47%) cases in which blood cultures were obtained, indicating the serious nature of the infections in many cases. Staphylococcus aureus is widely prevalent in healthy persons. Given its ubiquity and the capacity to cause a broad array of infections, an effective host response must play an important role in preventing infection. This host response is immunologically nonspecific, in that it depends upon the effectiveness of mechanical barriers to invasion and, once invasion takes place, the interaction of PMN, complement, and antibody that is probably present in serum of all immunologically competent adults rather than sensitization of B or T lymphocytes by any identifiable antigens specific to S. aureus. Analysis of the present cases calls attention to S. aureus as an opportunistic pathogen, 1 that only infrequently causes serious infection in otherwise healthy persons. Nearly every patient in this series had 1 or more medical condition thought to predispose to infection; 279 such conditions were identified, representing an average of 2.3 per person. A break in the natural barrier to infection was also present in the majority of cases, for example, trauma, wound, or pre-existing decubitus ulcer in skin and soft tissue infections; endotracheal tube in pneumonia; and a catheter bypassing urethra or skin in urinary and vascular infections, respectively. The tendency for patients to be infected with S. aureus repeatedly (mean number of infections, 1.4 per patient) reflects the chronicity of many predisposing factors and, perhaps, of colonization as well. Staphylococcus aureus has a special predilection to cause infections involving prosthetic devices, perhaps related to its affinity for fibronectin, laminin, and other serum proteins that can mediate attachment to foreign material; 46 of 162 (28%) infections were associated with the presence of a foreign body. Such infections are difficult to eradicate with antibiotic therapy alone, perhaps because of a change in the metabolic state of adherent bacteria, and removal of the foreign body is generally required for cure.(ABSTRACT TRUNCATED AT 400 WORDS) |
8041241 | Goodpasture syndrome: molecular and clinical advances. | Goodpasture syndrome is a rare but important autoimmune disorder characterized by pulmonary hemorrhage and glomerulonephritis. Typically striking young men, it is rapidly progressive and fatal unless treated early. Although the pathogenesis is largely unknown, recent investigations have established that antibodies are directed against the noncollagenous domain of the alpha 3 chain of type IV collagen. Differences in expression and exposure of this chain account for the tissue selectivity of the antibodies and the pulmonary and renal targets of clinical disease. Certain individuals appear at risk by virtue of HLA association, but why only some develop GS remains unclear. Intriguing observations suggest that cigarette smoking, infection, or chemicals expose the antigen, leading to antibody production in genetically susceptible individuals. Before plasmapheresis was available to remove antibodies, prognosis was bleak, and most patients died or were left with permanent renal impairment. Current combination therapy with plasmapheresis and immunosuppressive drugs is unlikely to be successful unless instituted early in appropriate patients. Fortunately, the autoimmune process is limited, as demonstrated by the small number of reported cases of recurrent disease. |
8041240 | The management of acute respiratory infections in Honduras: a field test of the Focused Ethnographic Study (FES). | The World Health Organization has recently developed an ethnographic research manual, The Focused Ethnographic Study (FES) for ARI, whose purpose is to facilitate Acute Respiratory Infection (ARI) program development by providing information about the context in which families perceive and respond to ARI, and by identifying factors that facilitate or impede prompt care-seeking for children with pneumonia. The methodology is focused around answering a set of pre-defined "Programme Managers' Questions" which represent the main concerns and needs of ARI programs. The FES is designed to address both the need for in-depth information about the household and community-level factors which affect the management of ARI, and the need for timely, program relevant, and focused information. A field test of this manual was conducted in Honduras, and a number of recommendations to the local ARI program were developed concerning improving communication about ARI with mothers of young children. The Honduran field-test of the FES shows how systematic ethnographic research can be conducted and translated into concrete recommendations for bridging the social and communication gap which so often exists between health workers and the communities they serve. |
8041239 | Acute respiratory illnesses in children under five years in Indramayu, west Java, Indonesia: a rapid ethnographic assessment. | A rapid, focused ethnographic study was carried out in a rural area of West Java, Indonesia to identify local beliefs, perceptions, and practices surrounding acute respiratory infections (ARI) in infants and young children. The study incorporates key informant interviews, open-ended interviews, and structured data collection from fifty mothers of young children selected to represent the geographical settlement pattern in the area: structured interviews with biomedical and indigenous health care providers; and structured interviews with fifty mothers who sought health care for an infant or young child with a respiratory illness. The most commonly perceived cause for ARI in children was air entering the body through some type of chill, exposure to draft or breeze, or change of weather. When fever or difficult breathing was present, mothers tended to increase the number and diversity the types of medicines used. Mothers recognized difficult as well as rapid breathing, both being described as "difficult breathing." More concern was expressed about fever than about difficulty in breathing. Effective medical care was more likely to be delayed for infants than for older children; infants were also more likely to be taken to an indigenous healer as the first-choice provider. Infants were less likely to receive an effective drug regimen even if appropriate medication was prescribed, because mothers commonly take the drugs in order to deliver them to the infant through breast milk. |
8041238 | Focused ethnographic studies in the WHO Programme for the Control of Acute Respiratory Infections. | Focused Ethnographic Studies (FESs), developed and sponsored by the World Health Organization (WHO) Programme for the Control of Acute Respiratory Infections (ARI), have facilitated ethnographic research dedicated to determining key household behaviors and understandings surrounding respiratory infections--particularly pneumonia--in children. The FES design emphasizes anthropological theory and methods while limiting the scope and duration of fieldwork to a specific "program-relevant" research problem. Findings from FES studies provide evidence of the rich vocabulary of ARI-related signs and concepts, and the interplay of structural and cultural factors that affect care-seeking for children with pneumonia. |
8041237 | The Marathi "taskonomy" of respiratory illnesses in children. | The reduction of childhood mortality from respiratory infections depends upon a case management strategy which encourages the decision to seek treatment. The research discussed, conducted in Pachod, Maharashtra, India, uses a "taskonomic" approach to understanding the diagnosis of illness and treatment decisions. This approach views treatment decisions as a result not only of local conceptual models of illness, but also of the specific circumstances of illness episodes involving different types of social relationships and control over resources. |
8041236 | Acute respiratory infections (ARI) in rural Bangladesh: perceptions and practices. | Acute Respiratory Infections (ARI) are a major cause of death in children under five in rural Bangladesh. A popular strategy for lowering ARI mortality in such settings includes detecting and managing pneumonia in children at the community level. The success of programs using this approach requires a well-trained community-based cadre of health workers and the appropriate utilization of services provided. Determinants of health care seeking behavior are clearly of interest in this regard. A qualitative study was conducted in Matlab, Bangladesh to describe community perceptions of signs and symptoms of ARI, case management behavior, and constraints to service utilization. Mothers recognized pneumonia and thought it to be caused by "exposure to cold." They were able to identify labored breathing, chest retractions, lethargy, and inability to feed as signs of severe disease needing treatment outside the home. Nevertheless, similar illnesses were sometimes believed to be due to attack by evil influences. In these cases, spiritual healers were sought and allopathic treatment was avoided or delayed. The mothers' observance of purdah and "proper" behavior were reported to play a role in prevention of child death from disease. Implications of this belief and its impact on service utilization are discussed. Suggestions for program managers are made in addition to recommendations for further research. |
8041235 | Acute respiratory illness: popular health culture and mother's knowledge in the Philippines. | Acute respiratory infection (ARI) is one of the chief causes of morbidity and mortality in the third world. This ethnographic study of ARI in the Philippines draws attention to local knowledge, sign recognition, perceptions of severity, and cultural factors influencing health care seeking. The mix of research methods used to generate data on these issues is discussed. |
8041234 | Insights from community-based research on child pneumonia in Pakistan. | Although pneumonia is a major cause of death in Pakistan, little is known about community beliefs and practices surrounding the disease. In this study, 35 mothers and four self-trained allopathic practitioners were interviewed in Karachi squatter settlements and rural Punjab. The findings indicate that maternal ideas about chest anatomy and the cause of pneumonia (principally "coldness") are very different from biomedical concepts. Further, mothers judge fast breathing impressionistically and tend to attribute it to fever alone. Nevertheless, they know that it is abnormal and most also link chest indrawing with pneumonia. Only mothers lacking other options take their children to government health facilities. Instead, most turn to private (frequently unlicensed) practitioners, although observation shows that such individuals are unable to diagnose pneumonia correctly and that they build their practices around the indiscriminate use of antibiotics. The study demonstrates that the target of ARI education in Pakistan should extend beyond government doctors to mothers and private practitioners as well. |
8041232 | The order of drug administration: its effects on the interaction between cocaine and ethanol. | To investigate the pharmacologic effects of the interaction between cocaine and ethanol, six male, paid volunteers familiar with the use of both ethanol and cocaine were tested in a dose-response, placebo-controlled, single-blind, randomly-assigned, cross-over design. Cocaine HCl (1.25 and 1.9 mg/kg) or placebo (lidocaine and mannitol) was given by nasal insufflation (snorting). Thirty minutes after cocaine snorting, ethanol (0.85 g/kg) or placebo was administered in divided doses over a thirty minute period. Cocaine and cocaethylene plasma concentrations, blood ethanol levels, subjective ratings of drug effects, heart rate and blood pressure were measured. Statistical analysis of the effects of cocaine snorting before ethanol ingestion indicate that: 1) cocaine did not alter the blood ethanol levels or the ratings of ethanol intoxication; 2) cocaethylene was formed and appeared in plasma more slowly and in concentrations lower than those of its parent compound; 3) the appearance of cocaethylene in plasma did not alter the decline of cocaine's subjective and heart rate effects; and 4) cocaine plasma concentrations were not increased and no augmentation of the subjective and heart rate effects of cocaine occurred. This latter finding, is in sharp contrast to the significant increase in cocaine plasma concentration and augmentation of cocaine's subjective and heart rate effects produced when ethanol is ingested prior to cocaine snorting. |
8041231 | MTT-assay and neutral red release (NRR)-assay: relative role in the prediction of the irritancy potential of surfactants. | A comparative study on the in vitro and in vivo irritancy of anionic, amphoteric and non-ionic surfactants was performed. In vitro ED50 values of the surfactants were determined by two cytotoxicity assays, the dimethylthiazoldiphenyltetrazoliumbromide (MTT) assay and the neutral red release (NRR) assay on serum-free cultured human foreskin keratinocytes. In vivo human irritancy data were obtained by a 24 hour occlusive patch test in volunteers and the irritant skin response quantified by visual scoring, evaporimetry and colorimetry. A close relationship between the evaluation methods of the patch test was observed (r = 0.92 to r = 0.96), confirming that the 'bioengineering' methods, such as evaporimetry and colorimetry are suitable for measuring skin irritation. For six surfactants evaluated we found a good correlation (r = 0.91) between the ED50 values of the MTT assay and the in vivo irritancy data. The NRR assay yielded less satisfactory correlation coefficients with regard to MTT assay (r = 0.42) and in vivo irritancy data (r = 0.46). This can be mainly attributed to a misinterpretation of the amphoteric and non-ionic surfactants by the NRR assay. While the NRR assay may better evaluate the anionic surfactants, the MTT assay seems to be more suitable when testing a broader range of chemically diverse surfactants. Limitations of cell culture systems are noted, although the potential usefulness of cultured human skin cells for skin irritancy testing has been clearly demonstrated. |
8041230 | In vitro fertilization of androgen sterilized mice. | In order to explore the effect of neonatal androgen administration on oocyte quality, ovulation induction and in vitro fertilization (IVF) were performed in androgen-sterilized mice. Androgen sterilized mice were produced by the subcutaneous injection of testosterone propionate (TP) at 5 days of age and ovulation induction was performed by pregnant mare's serum gonadotropin (PMSG)-human chorionic gonadotropin (hCG) treatment at 9 to 13 weeks old. The number of oocytes ovulated in TP-injected mice was 19.9 +/- 2.0 (Mean +/- SE) and was significantly less than that in normal mice (37.8 +/- 1.9; P < 0.01). The fertilization rate of oocytes retrieved from TP-treated mice (38.8%) was significantly lower than that from normal mice (60.3%; P < 0.01). These results indicate that neonatal androgen treatment has a detrimental effect on oocyte maturity. |
8041229 | Beneficial effects of myristic, stearic or oleic acid as part of liposomes on experimental infection and antitumor effect in a murine model. | Liposomes consisting of dicetyl-phosphate, cholesterol, lecithin and stearic or myristic or oleic acid, exert a protective effect for mice against experimental infection by Salmonella typhimurium, and delay both the onset and mortality B16 melanoma in these animals. Liposomes labelled with 3H-myristic acid were used as probes in the spleen and liver. We found that the treatment schedule rather than route of administration of liposomes, is important. The results show that in order to induce protection, preventive treatment must start at least three days before. Longer treatments do not increase the degree of protection, and treatments started at the same time as, or following experimental infection or tumor transplantation, have no effect. |
8041228 | NG-nitro-L-arginine-resistant endothelium-dependent relaxation induced by acetylcholine in the rabbit renal artery. | Studies were designed to determine the extent of the involvement of endothelium-derived relaxing factor(s) other than nitric oxide (NO) in vascular relaxation in response to acetylcholine (ACh) in the rabbit renal artery. ACh (10(-9)-10(-6) M) induced concentration-dependent relaxation of isolated endothelium-intact arterial rings preconstricted with noradrenaline. NG-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NO synthase, partly inhibited the ACh-induced endothelium-dependent relaxation, whereas it almost completely abolished the production of cyclic-3', 5'-guanosine monophosphate (cGMP) in these rings in response to ACh. Methylene blue, an inhibitor of guanylate cyclase, had an essentially similar effect to L-NAME on the relaxation. Indomethacin, an inhibitor of cyclooxygenase, had no effect. High concentrations of potassium chloride (to inhibit endothelium-dependent hyperpolarization), tetraethylammonium (TEA) or 4-aminopyridine (4-AP), a voltage-dependent or Ca(2+)-dependent K+ channel blocker, partly inhibited the relaxation while, in contrast, glibenclamide, an ATP-sensitive K+ channel blocker, had no effect. Ouabain, an inhibitor of Na+, K(+)-ATPase, also partly inhibited the ACh-induced relaxation, especially the higher concentration effect. Application of L-NAME together with ouabain, TEA, or a high concentration of potassium chloride completely abolished the relaxation. These results suggest that ACh-induced endothelium-dependent relaxation in the rabbit renal artery is mediated by NO, and by an other factor(s), which relaxes the vascular smooth muscle through opening K+ channels other than ATP-sensitive ones, and/or through the activation of a Na+, K(+)-pump. |
8041227 | Evaluation of nefazodone as a serotonin uptake inhibitor and a serotonin antagonist in vivo. | Nefazodone (2-[3-[4-(3-chlorophenyl)-1-piperazinyl]propyl]-5-ethyl- 2,4-dihydro-4-(2-phenoxyethyl)-3H-1,2,4-triazol-3-one) has been reported to be effective in the treatment of depression. Antagonism of serotonin type 2A (5HT2A) receptors, as well as inhibition of the serotonin (5HT) uptake carrier, has been suggested to contribute to the antidepressant action of nefazodone in vivo (Eison et al., 1990). Nefazodone weakly antagonized the quipazine-induced rise in rat serum corticosterone levels and the quipazine-induced increase in rat hypothalamic 3-methoxy-4-hydroxy-phenylglycol sulfate, suggesting blockade of 5HT2A receptors in vivo. Nefazodone, however, failed to antagonize the p-chloroamphetamine-induced depletion of mouse or rat brain 5HT, displaying a lack of effect on the 5HT uptake carrier. These data extend previous in vitro and in vivo data (Eison, et al. 1990) reporting nefazodone to be an antagonist at 5HT2A receptors, but fail to show inhibition of the 5HT uptake carrier in the same dose range. |
8041226 | Effect of chronic losartan potassium treatment on fructose-induced hypertension. | Carbohydrate enriched diets have been shown to elevate blood pressure in the rat. The precise mechanism by which carbohydrate feeding elevates blood pressure is not known. We evaluated the role of the renin-angiotensin system in the etiology of fructose-induced hypertension. Losartan potassium, an angiotensin II (AII) Type 1 (AT1) receptor antagonist, was utilized to assess the blood pressure response to fructose treatment. Male Sprague-Dawley rats were divided into 3 groups. Rats in the control group were fed regular chow. The other two groups were fed 60% fructose diet for 4 weeks. One of these groups was chronically treated with losartan potassium in drinking water. Throughout the study there was no significant difference in body weight between the three groups. There was a significant increase in blood pressure of fructose-treated rats within one week of treatment which remained elevated for the remainder of the study. Chronic losartan treatment significantly attenuated the rise in blood pressure. Within two weeks both the dipsogenic response and the pressor response to AII demonstrated complete blockage of AII receptors. These results suggest that the renin-angiotensin system plays a role in the development of fructose-induced hypertension. |
8041225 | NE-100, a novel sigma receptor ligand: effect on phencyclidine-induced behaviors in rats, dogs and monkeys. | Phencyclidine (PCP)-induced psychosis is a useful animal model for studies on schizophrenia. N, N-dipropyl-2-[4-methoxy-3-(2-phenylethoxy)-phenyl]- ethylamine monohydrochloride (NE-100) had no effect on conditioned avoidance responses (CAR) in rats, whereas, the PCP-induced impairment of avoidance inhibition was attenuated by NE-100. The PCP-induced ataxia or decreased attention in rhesus monkeys was to some extent overcome by NE-100. In dogs, PCP-induced either head-weaving behavior or ataxia, effects which were blocked by NE-100. Administration of PCP led to an increase in beta-2 and a decrease in delta relative power (RP) activity in cortical background spectral electroencephalographics (ECoG) in dogs. While NE-100 in itself showed no significant change in beta-2 and delta RP, NE-100 did block the PCP-induced beta-2 increase and delta decrease. These findings indicate that NE-100 attenuates the effect of PCP in experimental animals. This drug is being considered as a therapeutic for the treatment of patients in the schizophrenia. |
8041224 | Antisense oligodeoxynucleotide to a delta-opioid receptor given intrathecally blocks i.c.v. administered beta-endorphin-induced antinociception in the mouse. | The antinociception induced by supraspinally administered beta-endorphin is mediated by the release of Met-enkephalin and subsequent stimulation of delta-opioid receptors from the spinal cord in mice. Repeated intrathecal administration of an antisense oligodeoxynucleotide against delta-opioid receptors selectively attenuated i.c.v. administered beta-endorphin-induced antinociception without any effect on the antinociception induced by mu-opioid receptor agonists, morphine and DAMGO, or kappa-opioid receptor agonists, U50,488H. A random sequence oligodeoxynucleotide was inactive against beta-endorphin-induced antinociception. The study confirms previous findings that the antinociception induced by beta-endorphin is mediated by the stimulation of the delta-opioid receptors in the spinal cord. |
8041217 | [Inadequate TSH secretion. Clinical features, diagnostic criteria, and therapeutic possibilities]. | Inadequate secretion of TSH (IST) is a disorder which is diagnosed more frequently and earlier after the introduction of new immunoassay techniques which can distinguish between normal and suppressed TSH levels. For diagnosis high or unsuppressed TSH in required in the presence of elevated levels of the thyroid hormones. Its etiology may be tumor (TSH secreting pituitary adenoma) or non tumoral due to pituitary or generalized resistance to the thyroid hormones. Differential diagnosis between both etiologies is not easy, and several tests have been proposed but are not always discriminatory. Five cases of IST are presented in whom the diagnostic, clinical and therapeutic criteria have been analyzed. The cases of neoplastic IST (patients n.o 3, 4, and 5) showed a loss in circadian rhythm of TSH and absence of suppression with triiodothyronine (T3), 3,5-diiodo 4-(3'-iodine 4'-hydroxyphenoxi) phenylacetic acid (TRIAC) and with bromocriptine. The circadian rhythm of TSH was maintained in the non neoplastic IST (patients n.o 1 and 2) as was suppressed with T3, TRIAC and bromocriptine. The subunit-alpha/TSH quotient and TSH response to TRH were variable with no stimulation being observed with metoclopramide in any case. Upon the demonstration of unsuppressed circulating TSH in the presence of biochemical hyperthyroidism, IST should be suspected to avoid erroneous diagnosis and treatments. Differentiation between neoplastic and non neoplastic origin may be difficult since the biochemical and neuropharmacologic parameters are not always discriminatory. |
8041214 | [Evaluation of immunogenicity and safety in healthy adults of an inactivated anti-hepatitis A vaccine]. | The evaluation of the safety and immunogenicity of an inactivated vaccine against the hepatitis A virus (HAV) in healthy adults was performed. A descriptive clinical trial was carried out including a population of 100 healthy subjects of ages from 19 to 25-years. The subjects were intramuscularly injected (deltoid muscle) with an inactivated vaccine against hepatitis A (720 units ELISA) following a schedule of 0.1 months and a booster dose at 6 months. The titers of anti HAV antibodies were determined by the ELISA method prior to vaccination and following the administration of each doses. The safety of the vaccine was also parallelly evaluated after each doses from both a local and systemic point of view. With respect to safety, local signs and symptoms were presented in 34.6% of the subjects while systemic signs and symptoms were observed in 6.8% following administration of the 3 doses. At one month of the first doses 95.8% of the subjects had seroconverted (> or = 20 mUI/ml) with this rising to 100% at one month of receiving the second and third doses. The geometric mean of the antibody titer one month after having received each of the three doses was 158 mUI/ml, 832 mUI/ml and 4,135 mUI/ml, respectively. The vaccine was well tolerated and demonstrated great safety with a 100% rate of seroconversion following the primary cycle with two doses. The administration of the reminder doses at 6 months increased the antibody titer five fold after the primary cycle. |
8041213 | [The effect of moderate intake of alcohol during pregnancy on the weight of the newborn]. | There is currently no doubt concerning the detrimental effects of the intake of high doses of alcohol during pregnancy. Nonetheless, there has been some controversy regarding the effects of intake of low or moderate quantities of alcohol. The aim of the present study, carried out within the framework of a more extensive European study (EUROMAC), was to specifically analyze the relation between moderate intake of alcohol in pregnant women and the weight of the newborns. A prospective cohort study including 1,005 women who attended prenatal consultation in the Hospital La Fe of Valencia between 12 and 18 weeks of pregnancy during 1989 was performed. All the subjects were asked on alcohol intake during the week prior to the interview with data on other sociodemographic and biologic variables being collected. Variance analysis was carried out to evaluate the association of the weight of the newborn with alcohol intake as well as with each of the control variables. Multiple lineal regression analysis was performed by the minimum squares method to evaluate possible effects of confusion and interaction. Following adjustment for parity, weight of the mother prior to pregnancy, sex of the newborn, age at pregnancy and tobacco consumption, only a slight reduction in the weight of the newborns was observed in the category of intake greater than 90 g/week, however this difference was not statistically significant. The low or moderate intake of alcohol during the first months of pregnancy has no detectable effect on fetal growth. |
8041212 | [Factors associated with the use of gynecology services by climacteric women: a case-control study]. | The data and concepts described in the literature on menopausic women are based on observations and studies carried out in menopausic women attending medical or gynecological consultations and contrast greatly with the results obtained in women from a general population. In a case-control study 505 women between 45-55 years of age, 142 having attended a gynecological consultation (cases) and 363 taken from a randomized sample of the general population (controls) were evaluated. Information concerning sociodemography, climacteric phase, psychic morbidity and psychosocial factors as stressing events, social support and adjustment and satisfaction with roles was collected in a personal interview. The odds ratio (OR) was used as the means of association and multiple regression analysis was performed to control possible confusing factors. The cases were fundamentally young women in a premenopausic phase of a high social class belonging principally to a group of widows, separated or divorcees and a group of married women with high levels of association (OR = 14.7; OR 12.14). The women attending a gynecological consultation were characterized by having greater risk of lacking social support (OR = 8.94), presenting a greater frequency of vital severely stressing events over the previous year (OR = 2.55), and demonstrating greater insatisfaction in social adjustment (OR = 2.42) particularly in their sexual and matrimonial relations. Women attending medical, specially gynecological, consultations during climacteric years are not representative of the population of women in these years as a whole. Purely pharmacologic management, principally substitutive hormonal therapy, was the most wide-spread treatment of preventive character should be reestablished in accordance with the results with the most manifold and multifactorial orientations and foci. |
8041205 | [Primary ciliary dyskinesia. Electron microscopy study of ciliary ultrastructure]. | A 75 year old patient with respiratory infections since childhood, bronchiectasis and situs inversus is presented. Fiberoptic bronchoscopy was performed obtaining samples of bronchial mucosa which allowed the observation of the existence of ultrastructural lesions such as ciliary fusion, changes in the form of the cilia, microtubular changes and changes of the dynein arms by electronic microscopic study. Diagnosis of Kartagener's syndrome was established. In the case presented moderate clinical involvement was present which allowed the survival of the patient despite his advanced age. |
8041202 | [Meta-analysis of the efficacy of the combination of +rifampicin and doxycycline in the treatment of human brucellosis]. | The aim of this study was to determine whether a conclusion could be obtained through meta-analysis of the published trials on the relative efficacy of rifampicin and doxycycline versus streptomycin and doxycycline or another tetracycline (SD). The comparative and randomized trials identified by a search in the reference data base MEDLINE from 1967 to 1992 and through manual review of the articles cited in these studies or other reviews were included. The evaluation of quality was performed by a standardized scale. The differences in efficacy were expressed as odds ratio and the results were contrasted by the Mantel-Haenszel method. Heterogenicity was graphically analyzed by the Woolf method with an adjustment being made for small subgroups. The confidence intervals were calculated for each trial and for the combined data by the Cornfield method. Six trials including 581 patients of whom 544 were considered evaluable were analyzed. In the RD treatment group 261 (242 valid) patients were included with 268 (253 valid) being included in the SD group. Five cases of initial therapeutic failure were observed in each group without significant differences. The secondary effects described were very variable. Nonetheless no secondary effects obliging discontinuation of treatment were presented in the RD group with only one in the SD group with no differences between the two groups. Recurrences were presented in 5% and 39% in the RD group and in 0 and 17% in the SD group. In total 37 (16%) in the former group and 13 (5%) in the latter group. The Mantel-Haenszel odds ratio with respect to recurrence was 3.81 (CI 95%, 1.82-8.17; p = 0.00009). The total number of cures was 196 (81%) in the RD group and 232 (92%) in the SD group (Mantel-Haenszel odds ratio 0.36; CI 95%, 1.19-0.64; p = 0.0004). The inclusion of the quality index of the trials did not modify the statistical significance achieved. In human brucellosis the treatment of rifampicin and doxycycline presents a greater number of recurrence and lower number of cure than the classical treatment with streptomycin and tetracycline drugs. |
8041201 | [Replication indexes of the human immunodeficiency virus: predictive value of viral culture and blood antigens]. | To investigate the relation between markers of load and replication of the HIV [viral culture in plasma and in mononuclear cells of peripheral blood (MCPB) and antigen p24 (p24Ag) with the number of CD4+ cells and the prognosis of the patients. A retrospective study was performed in 188 patients who were analyzed and followed over a mean period of 431 days. The criteria of clinical progression (AIDS related complex, and new opportunistic infections), immunologic progression (CD4+ < 0.1 and < 0.05 + 10(9)/l) and death. Cocultures of HIV in free plasma and in MCPB were performed with the detection of complete AgHIV in the supernatant of the culture being used for analysis. Circulating p24Ag was determined by an ELISA technique without previous dissociation of the immunocomplexes. HIV cultures in plasma, in MCPB and p24Ag were positive in 27, 48 and 33% of the patients, respectively. The sensitivity of the indexes increased in agreement with the clinical progression of the patients and was inversely proportional to the depletion of the CD4+ lymphocytes (79% of the patients with CD4+ lymphocytes < 0.05 x 10(9)/l presented positive HIV culture in plasma). Viremia in plasma and to a lesser measure p24Ag correlated with variables recognized as bad prognosis and were found to be predictive of unfavorable evolution. Multivariate analysis demonstrated that pertenence to a symptomatic group and the presentation of a number of CD4+ lymphocytes of less than 0.2 x 10(9)/l were independent factors associated to the positivity of the viral culture in plasma and p24Ag. The culture positive in MCPB was principally related with the volume of blood analyzed. The risk of death was 6.38 fold greater in the presence of a positive plasma culture and 2.02 fold greater in the presence of positive p24Ag. In contrast, the unquantified positive HIV culture in MCPB showed no statistical significance in relation with patient survival. Positive HIV culture in plasma was the greatest prognostic index in patients with a number of CD4+ lymphocytes less than 0.2 x 10(9)/l. Unquantified cell culture had no predictive significance. To establish the prognosis of patients, the indexes of viral replication should not be used in isolation. |
8041200 | [Evaluation of the efficacy of chelation therapy with deferoxamine in patients with thalassemia major]. | The current treatment of thalassaemia maior (TM) is based on a hypertransfusion regimen, with deferoxamine (DFO) chelation therapy to minimize the consequences of iron overload. To evaluate the long-term efficacy of chelation therapy, a group of 9 patients treated for a period of 9 years was studied. The mean age of patients at the beginning of chelation therapy was 7 years. The age range at the moment of the study was 11 to 21 years. Pre-transfusion haemoglobin values were maintained above 10 gr/dl. DFO was administered by 10-hour sub-cutaneous infusion, 5 or 6 days a week at a dose of 40 mg/kg. Different iron overload parameters were considered, with special attention to cardiac function, growth and endocrinologic development. Signs of DFO toxicity were also studied. The final mean iron elimination rate was 72.6%. One patient died from cardiac haemosiderosis. Eight of the 9 patients showed significant growth impairment and 7, who have attained puberal or post-puberal age, suffer from one or more endocrinologic disorders (6 hypogonadism, 2 diabetes mellitus, 2 hypothyroidism and 1 hypoparathyroidism). The only toxic effect observed was transient crystalline opacity in 2 patients. Despite the early initiation of chelation therapy, TM patients receiving hypertransfusion regimen showed iron overload, with myocardiopathy, growth retardation and several endocrinologic disorders, mainly secondary hypogonadism, glucose metabolism disfunction and primary hypothyroidism. |
8041199 | Recognition of maternal identity in preterm and fullterm mothers. | The purpose of this exploratory and descriptive study was to investigate the maternal role attainment process of the preterm mother by comparing the endpoint of the process--maternal identity--in preterm and fullterm mothers. Forty-two first-time mothers, 21 preterm mothers and 21 fullterm mothers, were interviewed once at approximately one year post-birth. Qualitative and quantitative phenomena were examined. Qualitative data were collected via semi-structured interviews. Quantitative data were collected with instruments that measured maternal role attainment variables. Content analysis of the maternal identity recognition event revealed eight commonly discussed themes. Analysis of the quantitative data revealed no statistically significant relationships between length of gestation and any of the maternal role attainment variables. Also, no difference was found between preterm and fullterm mothers in the mean timing of the recognition of maternal identity. However, a 10-week difference in the median timing of maternal identity recognition was found. Sixty-two percent of the fullterm mothers recognized a maternal identity by two weeks after delivery, whereas only 24% of the preterm mothers experienced maternal identity recognition within this time frame. A statistically significant relationship was found between the timing of maternal identity recognition and maternal affective perception of the infant. The more positive the maternal affective perception of the infant, the earlier was the timing of maternal identity recognition. The study concluded that preterm mothers experienced a maternal role attainment process similar to fullterm mothers except that identity recognition was relatively delayed. The themes described by the preterm mothers tended to be qualitatively different and focused on denied maternal role experiences, especially denied contact with the infants and denied rights in relation to the infants. |
8041186 | The modified Senning operation for cavopulmonary connection with autologous tissue. | A modified Senning technique was used for intraatrial channeling of the systemic venous blood into the pulmonary arteries to create a Fontan circulation in 26 children, six with tricuspid atresia and 20 with complex congenital heart disease. In this technique a flap of atrial free wall tissue is used to create an atrial tunnel without artificial material. Eight patients had subaortic stenosis and required a Damus-Kay-Stansel procedure, in addition. Early mortality was two of 26 and late mortality one of 26. Pleural effusion was encountered in 17 of 26 patients, of whom four had a pericardial effusion, in addition. One patient required pacemaker implantation for complete atrioventricular block. Follow-up ranged from 2 months to 5 years. In this period the ability level index rose by one level. No thrombi were encountered in the right atrium/cavopulmonary tunnel. One patient required antiarrhythmic medication. Protein-losing enteropathy was diagnosed in one patient. This modified Senning technique has the advantage of avoiding the use of prosthetic material in the creation of a Fontan circulation and the potential for fewer long-term complications. |
8041185 | Surgical repair of subaortic stenosis in atrioventricular canal defects. | A 6-month-old male infant with partial atrioventricular canal defect and subaortic stenosis had a mitral valve releasing procedure to correct the subaortic stenosis with concomitant repair of the canal defect. An echocardiogram done 1 year after the operation shows no subaortic gradient and no mitral regurgitation. We present the details of the surgical technique and the common pitfalls in recognizing and treating this entity. |
8041184 | Long-term results of atrial correction for transposition of the great arteries. Comparison of Mustard and Senning operations. | Few data exists on the differences in long-term outcome between Mustard and Senning operations. We reviewed available data of all hospital survivors of these operations and assessed risk factors for late death and sinus node dysfunction. Of those patients undergoing the Mustard operation, 60 were hospital survivors (46 simple transposition, 14 complex); of those patients undergoing the Senning operation, 62 were hospital survivors (43 simple, 19 complex). Median duration of follow-up was 16 years (maximum 25 years) for Mustard operation, 11 years (maximum 20 years) for Senning operation. No reoperations were done, except for pacemaker implantation. No differences were found between the two groups with regard to baffle-associated problems, right ventricular failure, sudden death (6% in both groups), and functional status at final follow-up (New York Heart Association class I or II, except for four patients). For patients undergoing the Mustard operation, survival at 16-year follow-up was 91% with simple transposition and 60% with complex transposition (p = 0.027); for both groups of patients undergoing the Senning operation, survival at 16-year follow-up was 78%. Survival in the absence of rhythm disturbance at 16-year follow-up was 18% for Mustard operation and 53% for Senning operation (p < 0.001). In multivariate analysis, significant independent risk factors for late death turned out to be complex transposition (versus simple) and active arrhythmias. The only significant risk factor for the occurrence of sinus node dysfunction was the Mustard operation. We conclude that apart from the difference in the loss of sinus rhythm, no differences were found in the long-term clinical results of the two types of operations. |
8041183 | Anomalous origin of the left coronary artery from the pulmonary artery. Early results with direct aortic reimplantation. | Between January 1991 and June 1993, eleven children with anomalous origin of the left coronary artery from the pulmonary artery underwent direct aortic reimplantation of the left coronary artery at the German Heart Institute Berlin. The patients' ages ranged from 2.5 months to 10.5 years; six were infants. Three infants were intubated and their lungs ventilated before the operation, and one was resuscitated 2 days before the operation. The electrocardiograms of eight patients indicated deep Q waves. All but three of these patients had insufficient collaterals between the right and left coronary arteries. The entire group exhibited reduced left ventricular ejection fraction (minimum 15%) including mitral valve incompetence, which was moderate in six patients and severe in three. All six infants underwent emergency operations, and the remaining children, who were older, underwent elective operations involving moderate hypothermic perfusion and cold crystalloid cardioplegia. Aortic cross-clamping time ranged from 22 to 79 minutes (mean 54 minutes). A two-coronary artery system was established in all patients by direct reimplantation of the anomalous left coronary artery into the ascending aorta. Three patients who also exhibited severe mitral valve incompetence underwent modified Kay mitral valve annuloplasty. A delayed sternal closure procedure (closure performed 1 to 10 days after the operation) was used on eight patients. A 10-month-old patient was successfully treated after the operation with a centrifugal left heart assist device and a 9-year-old patient received extracorporeal membrane oxygenation because of severe heart failure. No postoperative deaths occurred. Left ventricular end-diastolic volume decreased dramatically after the operation and returned to near normal values 1 to 9 months postoperatively. At the same time, the preoperatively depressed left ventricular ejection fraction returned to normal and mitral valve incompetence decreased or vanished in eight patients. Color Doppler echocardiograms (eleven patients) and coronary angiograms (three patients) indicated that the reimplanted left coronary artery was patent in all eleven patients during the follow-up period. Reimplantation of the left coronary artery into the ascending aorta is an effective method of establishing a two-coronary artery system in children with anomalous origin of the left coronary artery from the pulmonary artery. Mitral valve annuloplasty is recommended for patients who also have severe mitral valve incompetence. Prolonged assisted circulation must be used in cases of severe postoperative heart failure. |
8041182 | Free jejunal autograft combined with extensive esophagogastrectomy for unshuntable extrahepatic portal hypertension. | This is the first report of the use of a free jejunal autograft vascularized by the internal thoracic (internal mammary) artery and vein to restore continuity of the digestive tract after total gastrectomy and distal 65% esophagectomy for recurrent bleeding esophagogastric varices caused by unshuntable extrahepatic portal hypertension. The procedure was used in two young adults who, because of numerous previous abdominal operations, had a severely scarred and contracted intestinal mesentery that precluded conventional use of the small or large intestine with an intact blood supply to bridge the gap between the upper thoracic esophagus and the abdominal jejunum. Before referral, the two patients had 21 and eight bouts of variceal hemorrhage, respectively, that necessitated a cumulative total of 108 and 74 units of blood transfusion, necessitated 17 and 12 admissions to the hospital, and failed to respond to four and five operations and 14 and 18 sessions of endoscopic sclerotherapy. After extensive esophagogastrectomy combined with a free jejunal autograft, both patients have done well during follow-up of 9 and 3 years, respectively. Both have been in good to excellent health with stable weight, freedom from digestive tract bleeding, normal liver function, and no encephalopathy. These results confirm our recently reported conclusions regarding the uniform long-term effectiveness of extensive esophagogastrectomy in the treatment of unshuntable extrahepatic portal hypertension and suggest that thoracic and general surgeons familiar with microvascular techniques may find the free jejunal autograft to be useful in various circumstances in which it is necessary to replace all or a substantial part of the thoracic esophagus. |
8041181 | Experimental study on a new tracheal prosthesis made from collagen-conjugated mesh. | A new tracheal prosthesis was made from fine Marlex mesh reinforced with a continuous polypropylene spiral. The mesh and spiral were covalently grafted and further coated with pig collagen with the aim of promoting connective tissue infiltration and providing initial airtightness. Complete surgical resection and replacement of a segment (2 cm in length, three to five tracheal rings) of the cervical trachea was performed in 13 adult mongrel dogs. Two dogs died of pneumonia about 2 months after operation, and eleven dogs were killed between 3 and 26 months. The prostheses in all dogs were promptly infiltrated by the surrounding connective tissue and completely incorporated by the host trachea. Formation of respiratory epithelium, which lined the prosthetic lumen, was seen to various degrees, and, in five dogs killed at 6 months or more after reconstruction, confluent epithelialization was confirmed histologically from the upper to the lower anastomotic site of the prosthesis. Marked stenosis of the prosthetic lumen caused by excessive scar tissue growth was seen in three dogs, and ulceration on the luminal surface was seen in two dogs. These results indicate that this tracheal prosthesis is highly biocompatible and promising for the repair of tracheal defects after further investigation. |
8041180 | Preoperative mediastinoscopic assessment of N factors and the need for mediastinal lymph node dissection in T1 lung cancer. | The significance of preoperative N factor assessment in T1 lung cancer and the need for mediastinal node dissection in T1 N0 M0 cases were investigated. The results of mediastinoscopy were evaluated in patients with T1 adenocarcinoma or squamous cell carcinoma who underwent preoperative mediastinoscopy and thoracotomy from 1971 to 1991 (n = 164). Mediastinoscopy gave true negative results in 90% of patients, false negative in 1%, and true positive in 9%. The 5-year survival was 90% for patients with T1 N0 M0 disease who underwent nonradical dissection (n = 64) and 70% for those who underwent radical dissection (n = 61), indicating that the prognosis was significantly better (p < 0.05) with nonradical dissection. Distant metastasis was a common cause of death, and no death was related to local recurrence, whether nonradical or radical dissection had been performed. The results strongly suggest that preoperative mediastinoscopy and intraoperative node sampling are sufficient for assessment of N factors in T1 lung cancer. The possible relation between immunologic functional changes associated with mediastinal lymph node dissection and the prognosis in patients without evidence of positive lymph nodes should be clarified by a prospective randomized study. |
8041179 | Depletion of plasma vitamin C but not of vitamin E in response to cardiac operations. | The whole-body inflammatory response produced by cardiopulmonary bypass is an important cause of perioperative morbidity after cardiac operations. This inflammatory response produces reactive oxygen species and other cytotoxic substances, such as the cytokines. The generation of reactive oxygen species might deplete principal antioxidant micronutrients, that is, vitamins C and E and the carotenoids. Therefore, we have investigated the time course of the plasma concentrations of vitamins C and E and the carotenoids in 18 patients undergoing coronary bypass operations after randomization for previous vitamin E supplementation (300 mg dl-alpha-acetyl-tocopherol 3 times daily for 4 weeks) or placebo. Supplementation with alpha-tocopherol doubled the lipid-standardized plasma vitamin E concentration to 63.7 +/- 14.5 mumol/L when compared with that of the control subjects (31.2 +/- 9.0 mumol/L) before the operation. The plasma concentrations of vitamin C (36.0 +/- 19.0 mumol/L and 44.0 +/- 21.7 mumol/L, respectively) and of the carotenoids were not statistically different between the two groups at baseline. The absolute plasma concentrations of both vitamin E and the carotenoids decreased during and after cardiopulmonary bypass, but after correction for hemodilution the plasma concentrations of vitamin E and the carotenoids showed no decrease. The vitamin E concentrations in the erythrocytes did not change either. In contrast, the plasma concentration of vitamin C decreased in all subjects within 24 hours after the operation by roughly 70%. Correction for hemodilution still revealed a significant decrease in plasma vitamin C that persisted in most patients up to 2 weeks. In conclusion, the vitamin E and the carotenoid plasma concentrations are of no major concern during and after cardiac operations. In contrast, the serious depletion of vitamin C may deteriorate the defense against reactive oxygen species-induced injury during cardiac operations. |
8041178 | Vitamin E for coronary bypass operations. A prospective, double-blind, randomized trial. | Free radical lipid peroxidation contributes to the abnormal metabolism and ventricular function frequently seen after cardiac operations. Antioxidants may improve metabolic and functional recovery. A prospective, randomized, double-blind clinical trial was conducted to determine the effects of vitamin E (alpha-tocopherol) (n = 14) or a corn oil placebo (n = 14) in patients undergoing elective coronary bypass operations. The RRR-alpha-tocopheryl acetate doubled the alpha-tocopherol levels in the heart. Myocardial metabolism and ventricular function were assessed after the operation. Atrial pacing induced myocardial lactate production in the control patients but lactate consumption in the alpha-tocopherol-treated patients on bypass 25 minutes after crossclamp release. Left ventricular stroke work indices were higher, at similar ventricular volumes, in the alpha-tocopherol-treated group, which indicates improved preload recruitable stroke work, and diastolic compliance was greater 4 hours after the operation. The postoperative creatine kinase cardiac isoenzyme levels were lower in the patients who received alpha-tocopherol. Pretreatment with alpha-tocopherol sufficient to double the myocardial concentrations had a small but significant metabolic and functional effect after elective coronary bypass operations when compared with placebo. These results do not justify pretreatment of low-risk patients, but they do justify an evaluation in high-risk patients. |
8041177 | Effects of cerebroplegic solutions during hypothermic circulatory arrest and short-term recovery. | Previous studies have suggested that a simple crystalloid "cerebroplegic" solution may prolong the safe duration of hypothermic circulatory arrest. We tested the hypothesis that pharmacologic modification of the cerebroplegic solution would further enhance cerebral protection. Forty-six 4-week-old miniature piglets underwent core cooling to 15 degrees C nasopharyngeal temperature and 2 hours of hypothermic circulatory arrest. Twelve animals had a 50 ml/kg dose of saline infused into the carotid artery system at the onset of hypothermic circulatory arrest and repeat doses of 10 ml/kg every 30 minutes during arrest. Eleven animals received the same initial and repeat doses of University of Wisconsin organ preservation solution and 10 received University of Wisconsin solution with 7.5 mg/L of MK-801, an excitatory neurotransmitter antagonist. In 13 control animals blood was partially drained from the piglet before 2 hours of circulatory arrest at 15 degrees C and no cerebroplegic solution was infused. All solutions were delivered at 4 degrees C. Brain temperature (n = 24) at the onset of hypothermic circulatory arrest was 15.0 degrees +/- 0.1 degrees C (mean +/- standard error). Brain temperature after cerebroplegic infusion dropped to 13.0 degrees +/- 0.3 degrees C and stayed lower than brain temperature in the control group throughout the hypothermic circulatory arrest period. Recovery of cerebral adenosine triphosphate and intracellular pH determined by phosphorus 31 magnetic resonance spectroscopy (n = 22) was significantly improved by saline infusion and was further improved with University of Wisconsin solution and University of Wisconsin solution plus MK-801 (p < 0.001). Recovery of cerebral blood flow measured by microspheres (n = 24) also was augmented by University of Wisconsin solution (p < 0.001) but not in the presence of MK-801. The vascular resistance response to acetylcholine and nitroglycerin suggested that MK-801 has a direct vasoconstrictive effect. Recovery of cerebral oxygen consumption (n = 24) was increased by University of Wisconsin solution and University of Wisconsin solution with MK-801 (p = 0.002). Brain water content (n = 46) was significantly lower in all cerebroplegia-treated groups than in controls (p < 0.001). Cerebroplegia improves short-term recovery after 2 hours of circulatory arrest in hypothermic piglets. Pharmacologic modification with University of Wisconsin solution further improves the recovery of cerebral blood flow and metabolism. MK-801 does not augment the protective effects of University of Wisconsin solution and reduces the recovery of cerebral blood flow by a direct vascular action. Modified cerebroplegia may provide a novel approach to improved cerebral protection when prolonged hypothermic circulatory arrest is necessary. |
8041176 | Cardioplegia and vascular injury. Dissociation of the effects of ischemia from those of the cardioplegic solution. | Although cardioplegic solutions successfully protect myocardial contractile cells against ischemic injury, their effect on the vasculature remains controversial. To address this we used a vascular bed preparation (isolated rat mesentery) that permits the study of vascular function without the coincident changes in contractile status that affect vascular tone (and hence the assessment of vascular function in isolated hearts). Smooth muscle cell contraction was assessed by measurement of the vasoconstrictor response to phenylephrine, and relaxation was assessed by measurement of the vasodilator responses to sodium nitroprusside and the endothelium-dependent relaxant adenosine triphosphate. After characterization of basal vascular function, mesenteries were subjected to normothermic ischemia for 60, 90, 120, 150, and 180 minutes (n = 12 for each time period; 6 preparations were subjected to ischemia alone and 6 to ischemia preceded by a 3-minute infusion of the St. Thomas' Hospital cardioplegic solution). The tissue was then reperfused for 20 minutes and vascular function reassessed. Ischemia alone caused progressive time-dependent deterioration in vasoconstrictor responses (99% +/- 13%, 90% +/- 10%, 63% +/- 6%, 51% +/- 10%, and 27% +/- 4%), endothelium-independent vasodilation (93% +/- 3%, 86% +/- 2%, 78% +/- 5%, 61% +/- 5%, and 38% +/- 9%), and endothelium-dependent vasodilation (93% +/- 3%, 96% +/- 2%, 94% +/- 2%, 87% +/- 7%, and 62% +/- 11%). There were similar time-dependent deteriorations in mesenteries subjected to ischemia coupled with cardioplegic solution that were not significantly different from any of the ischemia-alone groups when matched for ischemic times. Thus, for example, after 180 minutes of ischemia alone, the vasoconstrictor response was 18% +/- 3%, endothelium-independent vasodilation was 44% +/- 7%, and endothelium-dependent vasodilation was 40% +/- 9%. The results demonstrate that under the conditions of this experiment, the St. Thomas' Hospital cardioplegic solution neither protects nor injures the vasculature during an episode of ischemia and reperfusion. However, in studies with 150 minutes of normothermic ischemia, multiple infusions of cardioplegic solution (given every 30 minutes during ischemia) resulted in protection of smooth muscle and endothelial function. Thus, after multiple infusions, vasoconstriction to phenylephrine was 74% +/- 4%, vasodilation to nitroprusside was 81% +/- 6%, and vasodilation to adenosine triphosphate was 89% +/- 5%. In conclusion, when the St. Thomas' Hospital cardioplegic solution is used as a single infusion and coupled with ischemia, the solution fails to protect smooth muscle and endothelial function against ischemic injury, but some protection is obtained when the solution is infused intermittently throughout the ischemic period. |
8041175 | Nucleoside trapping during reperfusion prevents ventricular dysfunction, "stunning," in absence of adenosine. Possible separation between ischemic and reperfusion injury. | A previous study has shown that endogenous adenosine trapping during ischemia (by blocking adenine nucleoside transport and inhibiting adenosine breakdown) prevents myocardial stunning. In this study, we tested the hypothesis that delay of administration of inhibitors until reperfusion would similarly prevent myocardial stunning in the absence of entrapped adenosine. In both studies, a selective nucleoside transport blocker, p-nitrobenzyl-thioinosine, was used in combination with a potent adenosine deaminase inhibitor, erythro-9-(2-hydroxy-3-nonyl)adenine, to entrap adenosine (preischemic treatment) or inosine (postischemic treatment) in an in vivo canine model of reversible global ischemia. Twenty-five anesthetized adult dogs were instrumented (by sonomicrometry) to monitor left ventricular performance from the relationship between stroke work and end-diastolic length as a sensitive and load-independent index of contractility. Hearts of animals supported by cardiopulmonary bypass were subjected to 30 minutes of normothermic global ischemia and 60 minutes of reperfusion. Saline solution containing the pharmacologic agents were infused into the bypass circuit before ischemia (group 1) or during reperfusion (group 2). Control group (group 3) received saline before and after ischemia. Myocardial biopsy specimens were obtained before, during, and after ischemia, and levels of adenine nucleotides, nucleosides, oxypurines, and the oxidized form of nicotinamide-adenine dinucleotide were determined. Left ventricular contractility fully recovered within 30 minutes of reperfusion in the groups treated with erythro-9-(2-hydroxy-3-nonyl)adenine and p-nitrobenzyl-thioinosine (p < 0.05 versus control group). Myocardial adenosine triphosphate was depleted by 50% in all groups at the end of ischemia. Adenosine triphosphate recovered during reperfusion only in the group that was treated with inhibitors before ischemia (group 1). At the end of ischemia, adenosine levels were low (< 10% of total nucleosides) in the control group (group 3) and in the group treated only after ischemia (group 2). A high level of adenosine (> 90% of total nucleosides) was present in group 1. We infer that selective pharmacologic blockade of nucleoside transport, only after ischemic injury, accelerated functional recovery during reperfusion, even without trapping of endogenous adenosine during ischemia and without adenosine triphosphate recovery during reperfusion. Recovery of myocardial adenosine triphosphate required preischemic treatment and adenosine entrapment during ischemia and reperfusion. Therefore, nucleoside trapping may be used to prevent reperfusion-mediated injury after reversible ischemic injury. |
8041174 | Exogenous surfactant therapy in thirty-eight hour lung graft preservation for transplantation. | Previous work in our laboratory has documented alterations in surfactant composition and function after prolonged lung graft storage and transplantation in dogs (Am Rev Respir Dis 1993;148:208-15). To determine whether exogenous surfactant therapy was beneficial, we pretreated 13 canine double lung blocks with prostacyclin, flushed them with 4 degrees C modified Euro-Collins solution, and stored them at 4 degrees C for 37 to 38 hours. After left lung transplantation and immediately before reperfusion, eight dogs were administered 50 mg of bovine lung lipid extract surfactant per kilogram (50 mg/ml) directly into the left main bronchus and five served as nontreated control animals. Blood gases, peak inspired pressures, and individual pulmonary artery blood flows were measured every 30 minutes during 6 hours of reperfusion. The native right and transplanted left lungs were then lavaged and surfactant large and small aggregates and protein yields were analyzed. All nontreated animals had physiologic evidence of severe ischemia-reperfusion lung injury during reperfusion. Three of eight dogs treated with bovine lung lipid extract surfactant had near normal lung function at 6 hours of reperfusion, as reflected by maintenance of an oxygen tension/inspired oxygen fraction ratio of more than 400 mm Hg and a normal carbon dioxide tension. Five of eight dogs did not respond to surfactant therapy and had decreases in gas exchange identical to those of the control animals. Blood flow through the left pulmonary artery was maintained in the three animals that responded to exogenous surfactant, whereas flow significantly decreased to the left lung in all other animals, reflecting the patterns of gas exchange. In addition, the ratio of poorly functioning small surfactant aggregates to the well-functioning large aggregates isolated from lung lavage after 6 hours of reperfusion was decreased in surfactant-treated animals, especially in those exhibiting a beneficial physiologic response to surfactant therapy. We conclude that therapy with bovine lung lipid extract surfactant can result in excellent preservation of lung grafts after prolonged storage and transplantation, but that the results are not consistent. Further investigations are required to determine the factors responsible for the differential response to surfactant therapy. |
8041173 | Detection of canine allograft lung rejection by pulmonary lymphoscintigraphy. | We previously demonstrated that lymphoscintigraphy could be used to study pulmonary lymphatic flow. Radiocolloids, high-molecular-weight proteins tagged with radioactive markers, are injected percutaneously in the periphery of the lung. These molecules enter the lymph, are transported via lymphatic channels, and concentrate in the tributary hilar and mediastinal lymph nodes, where they can be visualized by nuclear scan. The goal of this study was to determine whether pulmonary lymphoscintigraphy could be used to detect allograft rejection after lung transplantation. Thirteen mongrel dogs underwent left lung allotransplantation. Cyclosporine 15 mg/kg per day and azathioprine 1 mg/kg per day were given orally for postoperative immunosuppression. Lymphoscintigraphic studies were obtained 1 week after the operation and then at weekly intervals. In five dogs (group A), immunosuppression was continued until the animal died or was put to death 6 weeks later. Lymphoscintigraphy demonstrated reestablishment of lymphatic drainage between the lung graft and the mediastinum in all the animals 2 to 4 weeks after transplantation. In eight dogs (group B), immunosuppression was discontinued after reestablishment of graft lymphatic drainage was documented by two consecutive lymphoscintigraphic studies. The dogs continued to be studied with weekly scans. In group B, lymphatic drainage from the lung graft to the mediastinum disappeared 1 to 4 weeks after immunosuppression was stopped. Rejection was diagnosed clinically and confirmed histologically with open lung biopsies and/or autopsies in all animals. This study shows that canine allograft lung rejection is associated with disappearance of lymphatic drainage from lung graft to mediastinum, which can be documented by pulmonary lymphoscintigraphy, a minimally invasive technique that can be easily repeated. Pulmonary lymphoscintigraphy may be useful for early detection of lung allograft rejection. |
8041172 | Cardiac transplantation: the Stanford experience in the cyclosporine era. | We analyzed our experience with 496 patients who underwent primary cardiac transplantation since the introduction of cyclosporine immunosuppression (Dec. 16, 1980, to Jan. 7, 1993). There were 388 male and 108 female patients. Mean recipient age was 40 +/- 16 years (range 0.1 to 70 years, median 44 years). Recipient diagnoses included coronary disease in 188, idiopathic cardiomyopathy in 196, viral cardiomyopathy in 35, and congenital heart disease in 28 patients. Donor age was 25 +/- 10 years (range 1 to 53 years, median 24 years). Graft ischemic time was 148 +/- 57 minutes (range 38 to 495 minutes, median 149 minutes). Operative mortality (hospital death) rate was 7.9% +/- 1.3% (70% confidence intervals). Multivariate logistic regression analysis revealed that (higher) pulmonary vascular resistance and gender (female) were the only independent predictors of hospital death (p < 0.05). Actuarial survival estimates for all patients at 1, 5, and 10 years are 82% +/- 1.7% (83% +/- 1.8% adult, 77% +/- 5.2% pediatric), 61% +/- 2.5% (65% +/- 2.5% adult, 64% +/- 6.6% pediatric), and 41% +/- 3.7% (40% +/- 4% adult, 54% +/- 8.6% pediatric), respectively. For 232 patients treated with triple-drug immunosuppression and induction with OKT3 since 1987, survival estimates at 1 and 5 years are 82% +/- 2.6% and 67% +/- 3.7%, respectively. Causes of death for the entire group were rejection in 29 (14% of deaths), infection in 69 (34%), graft coronary disease in 36 (18%), nonspecific graft failure in 6 (3%), malignancy in 19 (10%), stroke in 6 (3%), pulmonary hypertension in 6 (3%), and other causes in 30 (15%) patients. Actuarial freedom from rejection at 3 months, 1 year, and 5 years was 21% +/- 1.9%, 14% +/- 1.7%, and 7.2% +/- 1.5%, respectively (+/- 1 standard error of the mean). Estimates of freedom from rejection-related death at 1, 5, and 10 years were 96% +/- 1%, 93% +/- 1.4%, and 93% +/- 1.4%, respectively. Actuarial freedom from any infection at 3 months and at 1 and 5 years was 40% +/- 2.3%, 27% +/- 2.1%, and 15% +/- 2.0% and from infection-related death, 95% +/- 1.0%, 93% +/- 1.2%, and 85% +/- 1.9%, respectively. Actuarial freedom from (angiographic or autopsy proved) graft coronary artery disease at 1, 5, and 10 years was 95% +/- 1.2%, 73% +/- 2.7%, and 65% +/- 3.6% and from coronary disease-related death or retransplantation 98% +/- 0.7%, 84% +/- 2.2%, and 66% +/- 4.3%, respectively.(ABSTRACT TRUNCATED AT 400 WORDS) |
8041171 | Importance of severity of coronary artery disease for the tolerance to normovolemic hemodilution. Comparison of single-vessel versus multivessel stenoses in a canine model. | The response of global cardiovascular and regional myocardial function (as seen with sonomicrometry) to continuous, progressive hemodilution (Dextran 70) was compared in dogs with proximal circumflex coronary artery stenosis and dogs with proximal circumflex coronary artery and proximal left anterior descending artery stenoses. Hemodilution-induced failure, defined as greater than 50% loss in function or death of the animal, was determined for systolic shortening in the circumflex coronary artery and left anterior descending artery territories, mean arterial pressure, and maximum left ventricular rate of pressure rise. Time to failure was compared between groups by log-rank tests. Systolic shortening of the circumflex coronary artery failed at a similar median time point in both groups (30 minutes in the group with single-vessel stenosis and hemodilution versus 40 minutes in the group with multivessel stenosis and hemodilution). Systolic shortening of the left anterior descending artery (80 versus 50 minutes), mean arterial pressure (70 versus 50 minutes), and maximum left ventricular rate of pressure rise (70 versus 40 minutes), however, failed significantly later (p < 0.01) in animals with single circumflex coronary artery stenosis. A marked increase (+50%) in systolic shortening of the left anterior descending artery was observed during hemodilution only in the circumflex coronary artery stenosis group. The better hemodilution tolerance in the circumflex coronary artery stenosis group may be explained by the compensatory increase in myocardial contractile function in non-coronary flow-compromised myocardium, which seems to be crucial for global cardiovascular stability during hemodilution in the presence of coronary stenoses. |
8041170 | The St. Jude Medical prosthesis. A thirteen-year experience. | From May 1979 until July 1992, 1184 patients, 2 to 86 years of age (median = 59 years), received 1367 St. Jude Medical prostheses (578 aortic, 440 mitral, 3 tricuspid, and 170 multiple). Overall early mortality was 4% with 2.4%, 4.3%, and 8.2% after aortic, mitral and multiple valve replacement, respectively. Follow-up was 100% complete (4936 patient-years). Actuarial survival at 10 years (including both early and late deaths) was 71% +/- 4.1% after aortic valve replacement, 58.8% +/- 5.1% after mitral valve replacement, and 58.9% +/- 9.6% after multiple valve replacement. Multivariate analysis identified age, previous operations, diabetes mellitus, extent of coronary artery disease, preoperative New York Heart Association class, and additional procedures as independent prognostic factors for overall survival. All patients including 20 children (2 to 18 years of age) received sodium warfarin. The linearized risk per 100 patient-years for all embolic events (major and minor) was 2.4, 4.4, and 5.0 after aortic, mitral, and multiple valve replacement, respectively; when only major events were considered, the linearized risks were 0.33, 1.17, 1.54, respectively. Freedom from major systemic embolism at 10 years was 96% +/- 2% after aortic valve replacement, 88% +/- 4% after mitral valve replacement, and 89% +/- 3% after multiple valve replacement. Five patients had valve thrombosis, four of whom definitely received inadequate anticoagulation therapy. Ninety-seven patients had 107 episodes of anticoagulant-related hemorrhage (2.2/100 patient-years) accounting for 17 late deaths; 14 of the deaths involved an international normalized ratio in excess of 3.5. To reduce the rate of thromboembolism without increasing the rate of anticoagulant-related hemorrhage, we propose that the international normalized ratio should be kept between 2.5 and 3.0. No recorded structural failure or significant hemolysis was found in the absence of periprosthetic leak. This experience encourages us to continue using the St. Jude Medical prosthesis. |
8041169 | Experience with the Mitroflow aortic bioprosthesis. | From October 1985 to May 1990, the Mitroflow bovine pericardial valve was placed in the aortic position in 168 patients (97 men, 71 women) with a mean age of 69.7 years. Eighty-nine patients had isolated aortic valve replacement, and 79 had aortic valve replacement and additional procedures. Follow-up over 7 1/2 years includes 781 patient years (426 for isolated aortic valve replacement). Mean follow-up time is 56 months. Peak-to-peak gradients (in millimeters of mercury) measured in the intraoperative period averaged 11.0 +/- 8.7, 11.8 +/- 10.8, and 8.6 +/- 8.2 for 19 mm, 21 mm, and 23 mm valves, respectively. Hospital mortality was 7.3% (14 patients); all deaths were non-valve related. Late mortality of 20.1% in 31 patients resulted from cardiac failure (n = 8), sepsis (n = 4), valve reoperation (n = 1), non-cardiac causes (n = 15) and sudden, unknown causes (n = 3). Fifteen thromboembolic episodes occurred, but only three late thromboembolic episodes occurred in isolated aortic valve replacement without other risk factors. Four early and four late episodes of endocarditis occurred. Seven patients had clinical valve dysfunction, and five others required reoperation for structural deterioration, with one death. At 94 months, overall survival was 64% +/- 5%. Freedom from thromboembolic episode was 87% +/- 3% and 90% +/- 4% for isolated aortic valve replacement. Freedom from combined reoperation or clinical dysfunction was 75% +/- 8%: 64% +/- 15% for those under 70 years of age, and 87% +/- 7% for those 70 years of age and older. The valve has favorable hemodynamics. Durability begins to decline during the sixth year after implantation, possibly at a slower rate in patients older than 70 years of age. |
8041168 | Determinants of the occurrence of and survival from prosthetic valve endocarditis. Experience of the Veterans Affairs Cooperative Study on Valvular Heart Disease. | For the determination of the risk factors associated with the development of and death caused by prosthetic valve endocarditis, data were reviewed from 66 patients who were prospectively entered into the Veterans Affairs Cooperative Study on Valvular Heart Disease and in whom prosthetic valve endocarditis subsequently developed. Data were recorded at 13 medical centers between October 1977 and September 1982 in patients randomized to receive a mechanical valve (Bjork-Shiley spherical disc, n = 510 patients) or a bioprosthetic valve (Hancock porcine heterograft, n = 522 patients). The average rate of prosthetic valve endocarditis development was 0.8% per year over an average follow-up period of 7.7 years. Of the 66 patients in whom prosthetic valve endocarditis developed (5.8%), 15 cases occurred within 2 months of operation (early) and 51 occurred after operation (late). The most significant preoperative predictor of prosthetic valve endocarditis was active endocarditis at the time of operation (7.4% versus 0.9%) (p = 0.001). Early prosthetic valve endocarditis occurred more frequently in patients who underwent operation for multivalvular disease (p = 0.023). Significantly related perioperative variables were coma, prolonged mechanical ventilation, deep postoperative wound infection, postoperative jaundice, ventricular tachycardia, ventricular fibrillation, and replacement of more than one valve (p < 0.05). Multivariate predictors were hypoxia (p = 0.001), preoperative endocarditis (p = 0.003), preoperative valve lesion (p = 0.020), and resident surgeon (p = 0.05). Significant preoperative variables predictive of late prosthetic valve endocarditis were mitral stenosis and mixed mitral stenosis-regurgitation. The only multivariate predictor of late prosthetic valve endocarditis was superficial wound infection (p = 0.004). Of deaths attributable to prosthetic valve endocarditis, 41% occurred in patients treated with antibiotics alone, 48% occurred in patients treated with surgical intervention and antibiotics, and death resulted in both patients who received no treatment. No difference was found in the risk of early or late postoperative prosthetic valve endocarditis developing in patients receiving the mechanical valve versus those receiving the bioprosthetic valve. |
8041167 | Aortic dissection. Prevalence, cause, and results of late reoperations. | From January 1977 to September 1992, 143 patients underwent an emergency operation for type A acute aortic dissection. Because of the location of the intimal tear, the replacement of the ascending aorta was extended to the transverse arch in 42 patients (29.3%). One hundred ten patients (78%) survived the operation. During the same period, 32 patients had to be reoperated on once (n = 24) twice (n = 6), or three times (n = 2) for a total of 42 reoperations. Nineteen patients had had the initial repair in our institution, and 13 had been operated on elsewhere. Reoperation was indicated for aortic valve disease (n = 4), recurring dissection (n = 7) threatening aneurysmal evolution of a persisting dissection (n = 28), or false aneurysm (n = 3). The redo procedure involved the aortic root and/or ascending aorta in 15 cases (group I), the transverse arch alone in 7 cases (group II), the transverse arch and the descending aorta or the descending aorta alone in 10 cases (group III), or the thoracoabdominal aorta in 10 cases (group IV). The risk factors for reoperation have been analyzed in the 110 survivors initially operated on in our institution. Seven of 18 patients with Marfan's syndrome (38.8%) versus 12 of 92 without Marfan's syndrome (13%) were reoperated on (p = 0.023). None of the 30 patients surviving arch replacement at initial repair required a reoperation, versus 19 of 80 (23.7%) patients surviving a replacement limited to the ascending aorta (p = 0.013). The overall mortality rate of reoperation was 21.8% (7/32) with a risk of 16.6% (7/42) at each procedure (group I, 13.3%; group II, 0%; group III, 20%; group IV, 30%). Hospital mortality was influenced by emergency operation (5/10) (p < 0.005) and thoracoabdominal replacement (3/10) (p < 0.035). The late survivals after reoperation are 65.1% +/- 17.6% at 1 year and 55% +/- 19.63% at 5 years (Kaplan-Meier, confidence interval 95%). The late survivals, after the initial repair, of the patients undergoing reoperation are 89.6% +/- 11.0%, 79.3% +/- 14.7%, 53.9% +/- 18.1%, and 35.9% +/- 21.8% at 1, 5, 10, and 12 years, respectively. In conclusion, aortic dissection is an evolving process that may require one or several reoperations after the initial repair. At initial emergency operation, the resection of the entry site, when located on or extending to the transverse arch, has reduced the risk of reoperation, in our experience. Elective reoperation must be considered before the occurrence of complications, especially in patients with Marfan's syndrome.(ABSTRACT TRUNCATED AT 400 WORDS) |
8041156 | Nitric oxide inhibition in the treatment of the sepsis syndrome is detrimental to tissue oxygenation. | The manifestations of the septic syndrome are thought to be mediated by cytokines through their role in the production of nitric oxide (NO). It is hypothesized that the inhibition of NO production with an inhibitor such as NG-monomethyl-L-arginine (L-NMMA) may be beneficial in the treatment of septic shock. Sepsis was induced by the intravenous administration of Escherichia coli endotoxin (60 micrograms/kg) in six conditioned mongrel dogs (20-24 kg). Mean arterial pressure (MAP), heart rate (HR), central venous pressure (CVP), and pulmonary artery pressure (PAP) were continuously monitored. Cardiac output (CO), pulmonary capillary wedge pressure (PCWP), and arterial and mixed venous blood gases were obtained every 10 min. When the MAP decreased below 60 mm Hg, NO inhibitor L-NMMA was given by intravenous injection (25 mg/kg). Physiologic parameters were then measured at 2 and 5 min after L-NMMA injection. Subsequently, L-arginine (400 mg/kg), the substrate for the NO synthase enzyme, was administered and measurements were repeated at similar intervals. L-NMMA in septic canines produced a significant increase in MAP and SVR with a significant decrease in CO and tissue oxygenation (DO2 and VO2). These changes were reversed with the administration of L-arginine. There were no significant differences in the PCWP, CVP, PAP, or HR throughout the entire study. These results suggest that the inhibition of NO production by L-NMMA in a septic model produces elevated MAP and SVR at the expense of tissue oxygenation. Thus, its use, as a principal means of therapy for the septic syndrome, may not be appropriate because of detrimental effects on tissue oxygenation. |
8041157 | IVOX with gradual permissive hypercapnia: a new management technique for respiratory failure. | IVOX (intravenous oxygenator and CO2 removal device) augments venous gas exchange in patients with severe respiratory failure. Controlled hypoventilation with permissive hypercapnia reduces airway pressures during mechanical ventilation and augments CO2 exchange through the IVOX. To quantify the additive effects of gradual permissive hypercapnia and IVOX on gas exchange and reduction of airway pressures, 13 adult sheep underwent tracheostomy and severe smoke inhalation injury. Seven were mechanically ventilated alone (control), and six had mechanical ventilation, systemic anticoagulation, and implantation of IVOX (size 7 with 0.21-m2 surface area) (IVOX group). Both groups were anesthetized and paralyzed for 24 hr. In the IVOX group, minute ventilation was decreased in a stepwise fashion to produce a gradual increase in PaCO2, from 30 to 95 mm Hg, over 12 hr, and then sustained for an additional 12 hr. Sodium bicarbonate was given intravenously as necessary to keep arterial pH above 7.25. There were no significant differences in mean arterial pressure, cardiac output, or pulmonary artery pressure between the two groups. In the IVOX/permissive hypercapnia group, IVOX CO2 removal increased as a linear function of PaCO2 (y = 0.87x + 8.99, R2 = 0.80). IVOX CO2 removal was only 40 ml/min at normocapnia (40 mm Hg) but increased to 91 ml/min when PaCO2 was 95 mm Hg. Both peak inspiratory pressure and minute ventilation of the IVOX/permissive hypercapnia group were significantly lower than the control group, 30 +/- 4 mm Hg vs 51 +/- 3 mm Hg and 3.9 +/- 0.3 liters vs 8.4 +/- 0.5 liters (P < 0.05) respectively.(ABSTRACT TRUNCATED AT 250 WORDS) |
8041155 | Macrophage endotoxin tolerance: effect of TNF or endotoxin pretreatment. | Macrophages pretreated with low-dose endotoxin [lipopolysaccharide (LPS1)] have an altered response to subsequent endotoxin (LPS2) stimulation, a process known as endotoxin tolerance. In this study we investigated whether the LPS1 pretreatment effects were mediated primarily via tumor necrosis factor (TNF alpha). Murine peritoneal macrophages were pretreated in vitro with either TNF alpha or LPS1 and the effects on mediator production in response to a second endotoxin exposure, LPS2, were compared. Mediators in macrophage supernatant were measured using specific bioassays [TNF, interleukin-1 (IL-1), and IL-6] or enzymatic immunoassays [prostaglandin E2 (PGE2) and TNF]. Macrophage production of all mediators was stimulated by endotoxin in the absence of LPS1 pretreatment. Pretreatment with LPS1 completely inhibited LPS2-triggered TNF release whereas preexposure to TNF alpha had no effect. In contrast, LPS1 pretreatment significantly augmented IL-1 and PGE2 release in response to LPS2, whereas pretreatment using either high- or low dose TNF alpha did not. TNF, stimulated by an initial exposure to endotoxin, LPS1, is not solely responsible for the observed alterations in macrophage mediator release following a subsequent endotoxin stimulus (LPS2). Thus, the data suggest that endotoxin tolerance is mediated primarily by factors other than TNF. |
8041154 | Hypothermia enhances contractility in cerebral arteries of newborn lambs. | Hypothermia is the major factor influencing autoregulatory properties of the cerebral circulation in human infants undergoing hypothermic cardiopulmonary bypass. The present investigation evaluated the effect of decreased temperature on the contractility of isolated middle cerebral arteries obtained from newborn lambs. Reducing bath temperature from 37 to 21 degrees C caused a temperature-dependent increase in contractile tension, achieving 1.32 +/- 0.09 g above resting tension (0.75 g). Pretreatment with nonselective (alpha 1 and alpha 2) alpha-adrenoceptor antagonist, phentolamine (10(-5) M), with an inhibitor of nitric oxide synthase, NG-nitro-L-arginine methyl ester hydrochloride (10(-4) M), and with a cyclooxygenase inhibitor, indomethacin (10(-5) M), did not affect the contractile response to a decrease in bath temperature from 37 to 21 degrees C. Furthermore, cerebral arteries were responsive to both norepinephrine (constriction) and sodium nitroprusside (relaxation) and the sensitivity of cerebral arteries to the sympathetic neurotransmitter norepinephrine appears to be enhanced at low temperatures. We postulate that direct cerebral vasoconstriction and enhanced adrenergic contractility may be responsible for increased cerebrovascular resistance during and after hypothermic cardiopulmonary bypass with possible ischemic cerebral injury and neurological sequelae. |
8041153 | Precursor frequency analysis of bryostatin activated lymphocytes. | Bryostatin 1 (Bryo) is a potent activator of protein kinase C. When T cells are stimulated with Bryo and the calcium ionophore ionomycin (Io), they expand rapidly in low-dose IL-2 (20 U/ml). We have shown that Bryo/Io-activated T-cells from murine tumor-draining lymph nodes have striking antigen-specific antitumor efficacy in vivo. To account for the specificity despite using a nonspecific T cell activation method, it was postulated that the Bryo/Io combination might preferentially activate antigen-sensitized T cells. To test this hypothesis, an allogeneic response model was used. C57BL/6 mice were primed by intraperitoneal (ip) injection with DBA/2 mouse splenocytes. After 9 days, the C57BL/6 spleens were harvested and H-2d-specific cytolytic T lymphocyte (CTL) precursor frequency (PF) was determined by limiting dilution analysis (LDA). A portion of the same spleen cells was treated for 18 hr with Bryo/Io and expanded for 7 days in IL-2 (20 U/ml); the LDA was then repeated to analyze PF after expansion. The entire experiment was also done with responder and stimulator strains reversed (DBA/2 mice immunized with C57BL/6 cells). The resulting PF values were [table: see text] Normal spleen cells treated with Bryo/Io exhibited < 10% release vs the same targets at any effector:target ratio, ruling out nonspecific cytolysis after Bryo/Io. T lymphocytes or CD8+ T cells were selected from primed splenocytes and the PF values before and after Bryo/Io were analyzed. These data showed that the increase in PF after expansion could not be attributed to T cell or CD8+ cell enrichment alone.(ABSTRACT TRUNCATED AT 250 WORDS) |
8041152 | Estrogen inhibits sphincter of Oddi motility. | Gallstones and sphincter of Oddi dysfunction are both more common in women than men, suggesting that endogenous hormones may play an important role in these conditions. Female sex hormones are known to affect cholesterol metabolism and gallbladder motility. However, the effect of these hormones on the sphincter of Oddi has not previously been studied. We therefore tested the hypothesis that exogenous estrogen administration would inhibit sphincter of Oddi motility. Twenty-three male prairie dogs fed a nonlithogenic diet were studied. Under alpha-chloralose anesthesia, a side hole pressure-monitored perfusion catheter was positioned in the sphincter of Oddi and perfused with degassed water at 0.15 ml/min. Femoral arterial and venous catheters were placed. Sphincter of Oddi phasic wave frequency (F), amplitude (A), and motility index (MI = F x A), as well as arterial blood pressure (BP), were monitored for 10-min intervals before (control), during 20-min intravenous infusions of 0.1, 1, or 10 micrograms/kg beta-estradiol, and for 20 min after estradiol infusion. No response was observed at the 0.1- or 1-micrograms doses. Sphincter of Oddi motility was significantly (P < 0.05) reduced during estrogen infusion at the higher dose of 10 micrograms, primarily due to decreased phasic wave frequency. Sphincter motility remained depressed for at least 20 min following estrogen infusion. We conclude that estrogen effects on the sphincter of Oddi may contribute to the higher incidence of gallstones and sphincter dysfunction seen in premenopausal women. |
8041151 | Dietary fish oil enhances macrophage production of nitric oxide. | Nitric oxide (NO) is recognized as an important mediator of hemodynamic regulation and multisystem organ failure (MOF). Although polyunsaturated fatty acids (PUFA) are known to modify the elaboration of some humoral mediators in MOF, their effect upon NO production has not been evaluated. This study was designed to examine the effect of omega-3 (omega 3) and omega-6 (omega 6) PUFA on macrophage production of NO, TNF, PGE2, and PGI2. Rats were fed diets of 18% by calorie safflower oil (omega 6) or fish oil (omega 3) for 12 days. Bronchoalveolar macrophages (BAM) were divided into group A (medium only), group B (0.5 microgram/ml PGE2 or PGI2 + medium) or group C (10 microM indomethacin+medium). Cells were stimulated with 100 U/ml interferon-gamma and 10 micrograms/ml Escherichia coli-LPS. In group A, BAM from animals fed omega 3 produced significantly more NO (3.64 vs 1.92 microM, P < 0.05) and TNF (8.52 vs 1.75 micrograms/ml, P < 0.05) than BAM from omega 6-fed animals. The addition of exogenous PGE2 or PGI2 (group B) ablated the difference in NO and TNF observed in group A. Indomethacin also (group C) ablated the difference in NO and TNF production seen in omega 3- and omega 6-fed animals noted in group A. These data demonstrate that PUFA influence BAM production of NO and TNF. Changes in the omega 6-derived prostanoids may account for the differences in TNF production, but these data suggest that PGE2 and PGI2 are not responsible for the observed differences in NO production.(ABSTRACT TRUNCATED AT 250 WORDS) |
8041150 | The effect of combination cyclosporine and CTLA4-Ig therapy on cardiac allograft survival. | Transplant rejection requires not only T cell receptor/CD3 complex activation by foreign MHC, but also additional costimulatory signals, as T cell receptor activation alone is insufficient for induction of the immune response. The CD28 receptor on helper T cells, interacting with its ligand B7 on activated B cells or macrophages, provides this costimulus to support T cell activity. CTLA4Ig (a soluble CD28 receptor analog), binds B7 and inhibits CD28 activation. As cyclosporine (CsA) has many side effects and CTLA4Ig alone has a significant benefit upon cardiac allograft survival, we theorized that allograft survival could be improved by using CTLA4Ig with lowered dose CsA. In vitro, high-dose CTLA4Ig inhibited the mixed lymphocyte culture reaction (MLR) between MHC-incompatible rat strains. Furthermore, there was synergistic suppression of MLR by low-dose CTLA4Ig combined with low-dose CsA. In vivo studies used a cervical heterotopic transplant model. Control recipients received no immunotherapy. Experimental recipients received low-dose CsA (1.5 mg/kg/day im) x 14 days after transplant or CTLA4Ig (10, 50, or 150 micrograms IP x 7 days). Combination animals received both CTLA4Ig and CsA. These studies showed that low doses of CsA and CTLA4Ig were additive in vivo, although no additional benefit was seen when CsA was combined with high-dose CTLA4Ig. These data suggest that the combination of low-dose CsA plus CTLA4Ig may prove useful in clinical transplantation to maximize immunosuppression and minimize side effects. |
8041149 | Prolonged cardiac xenograft survival is induced by intrathymic splenocyte injection. | The shortage of suitable human organs currently limits widespread utilization of clinical transplantation. Successful xenotransplantation could potentially eliminate the shortage of suitable organs for transplantation. The present study determines the effect of intrathymic donor spleen cell injection on the survival of cardiac xenografts performed without post-transplant immunosuppression. Wistar-Furth rats served as recipients of Lewis rat cardiac allografts or Golden Syrian hamster cardiac xenografts either with or without intrathymic donor spleen cell injection. Some xenograft cohorts were pretreated with four doses of cyclophosphamide prior to cardiac transplantation. Graft function was assessed by daily graft palpation and rejection was defined as cessation of graft function. Cardiac allograft median survival time (MST) was 8 days in untreated recipients. Pretreatment with intrathymic donor spleen cell injection led to essentially indefinite allograft survival (MST > 100 days). Control xenograft survival was 3 days with no significant prolongation seen when intrathymic donor spleen cell injection was performed (MST = 2.5 days). The addition of pulse-dose cyclophosphamide resulted in markedly prolonged xenograft survival (MST = 30 days) compared to control (P < 0.01) and to cyclophosphamide alone (MST = 9.5 days, P < 0.01). Cardiac xenografts undergo a vigorous rapid rejection. The time course of rejection was not altered by the intrathymic presence of donor cells under conditions which lead to indefinite survival of cardiac allografts. A brief period of pretransplant cyclophosphamide treatment markedly improved the success of the thymic tolerance protocol in xenografts. This finding suggests that temporary inhibition of humoral immunity may be permissive for the development of thymic tolerance to cell-mediated immunity in xenotransplants. |
8041148 | Endotoxin pretreatment inhibits neutrophil proliferation and function. | Gut ischemia/reperfusion (I/R) induces lung injury by a mechanism that involves neutrophils (PMNs). We have previously shown that endotoxin (LPS), when administered after gut I/R, amplifies this lung injury, while treatment with LPS prior to gut I/R prevents lung injury. The purpose of this study was to determine whether LPS pretreatment (Pre Rx) alters the PMN inflammatory component of the gut I/R injury. Specifically, we focused on whether LPS Pre Rx effected (i) PMN stem cell proliferation, (ii) gut I/R-induced PMN priming, and (iii) gut I/R-induced PMN lung sequestration. Bone marrow was harvested from normal and LPS-pretreated (0.5 mg/kg, ip, 3 days prior) rats, and colony forming units--granulocyte/macrophage (CFU-GM) were quantitated using a soft agar culture technique. In another experiment, normal and LPS-pretreated rats were subjected to gut I/R (45 min superior mesenteric artery occlusion/6 hr reperfusion), and blood and lungs were then harvested. The in vivo priming of PMN was assessed by measuring the difference in superoxide production (O2-) with and without the activating stimulus, N-formylmethionyl-leveyl-phenylalanine (fMLP). The quantity of myeloperoxidase (MPO) was used as an index of the number of PMN sequestered in lung tissue.(ABSTRACT TRUNCATED AT 250 WORDS) |
8041147 | Evidence for a 5-HT4 receptor pathway mediating chloride secretion in the rat distal colon. | Serotonin (5-HT) is a potent secretagogue of chloride ion (Cl-) and a mediator of diarrhea in the carcinoid syndrome. We investigated the role of the 5-HT4 receptor pathway in mediating 5-HT-induced Cl- secretion that is seen as a rise in short circuit current (Isc) in the Ussing chamber. Rat distal colon was stripped of the muscularis, mounted in Ussing chambers, and short circuited. By cumulative concentration responses, 5-HT-induced rise in Isc was measured in the presence and absence of 0.1 microM of the nerve conduction blocker, tetrodotoxin (TTX). TTX was later added routinely to remove any effects of residual nerve tissue. 5-HT concentration response was measured in the presence and absence of the following 5-HT receptor antagonists: 10 microM 5-HTP-DP (5-HT1p), 1 microM methysergide (5-HT1-like and 5-HT2), 0.1 microM ketanserin (5-HT2), 0.3 microM ondansetron (5-HT3) 0.1, 0.5, 1 and 3 microM ICS 205-930 (5-HT3 and 5-HT4), and 0.1, 0.03, and 0.01 microM of the new selective 5-HT4 antagonist, SC 53606. Data were analyzed by ANOVA. TTX had no effect on EC50 for 5-HT. ICS 205-930 and SC 53606 produced dextral shifts in 5-HT concentration-response curves and at all concentrations a significant shift in the EC50 for 5-HT, except at 0.1 microM ICS 205-930. The Schild plot slopes for ICS 205-930 (0.8) and SC 53606 (0.7) were not significantly different from unity. The pA2 values were 6.5 and 7.2, respectively.(ABSTRACT TRUNCATED AT 250 WORDS) |
8041146 | Nitric oxide (endothelium-derived relaxing factor) attenuates revascularization-induced lung injury. | Aortic occlusion and revascularization (I-R) may lead to lung injury dependent on activated neutrophil adherence. Nitric oxide (NO) inhibits neutrophil adherence to endothelial cells. We studied the effect of increasing or decreasing NO levels with sodium nitroprusside (SNP) or N-nitro-L-arginine methyl ester (L-NAME) in an I-R lung injury model of 30 min ischemia followed by 120 min reperfusion. Sprague-Dawley rats (10/group) were randomized to controls, I-R, I-R treated with L-NAME (10 mg/ml/hr), and I-R treated with SNP (0.2 mg/ml/hr). Myeloperoxidase activity (MPO) was used as a measure of pulmonary neutrophil influx. Pulmonary endothelial permeability was measured by wet:dry weight ratio and bronchoalveolar lavage protein (BAL prot) and neutrophil counts (BAL PMN). Aortic occlusion and revascularization led to significant increases in pulmonary neutrophil influx (6.1 +/- 0.1 MPO u/g vs 3.05 +/- 0.4 MPO u/g in the control group, P < 0.001) and microvascular leakage; BAL prot (347 +/- 32 mg/ml in controls vs 454 +/- 16 mg/ml in the I-R group, P < 0.05); and BAL PMN (0.7 +/- 0.05 in controls vs 1.8 +/- 0.07 PMN/ml in the I-R group, P < 0.001). These changes were exacerbated further by administration of L-NAME (MPO = 8.9 +/- 0.7; BAL prot = 581 +/- 40 mg/ml; BAL PMN = 2.7 +/- 0.16 PMN/ml). Sodium nitroprusside therapy attenuated the I-R-induced lung injury (3.5 +/- 0.4 MPO u/g, P < 0.05 vs I-R; BAL prot = 330 +/- 61 mg/ml; BAL PMN = 0.9 +/- 0.1 PMN/ml).(ABSTRACT TRUNCATED AT 250 WORDS) |
8041145 | Captopril amelioration of renal reperfusion injury. | The purpose of this study was to determine whether angiotensin converting enzyme inhibition could ameliorate renal ischemic injury. Both a chronic rat model and a rat isolated perfused kidney (IPK) model were used. Adult rats were subjected to 60 min of left hilar crossclamping and right nephrectomy. Captopril (1 mg/kg) was given intravenously 5-10 min prior to clamping (CAP-pre, n = 5), at reperfusion (CAP-post, n = 5), or 30 min after reperfusion (CAP-30 min post, n = 5). Other groups of rats received enalapril (0.8 mg/kg iv) in the same manner (ENAL-pre, n = 5; ENAL-post, n = 5; ENAL-30 min post, n = 4). Serum creatinine in the treated groups was compared to ischemic control (NS, n = 7) for 7 days. In the IPK experiments, kidneys were similarly treated with CAP or ENAL. Vascular resistance (VR) and oxygen consumption (O2 CON) were determined from pressure, flow, and oxygen tension data for 60 min after initial equilibration. In the chronic model, Day 2 serum creatinine was significantly lower in all treated groups vs ischemic control. By Day 7, serum creatinine remained significantly lower in all ENAL-treated groups and in the CAP-30 min post group, although other CAP-treated groups had appreciably, although not significantly, lower creatinines, too. Histologic examination of CAP-pre kidney revealed intact morphology compared to ischemic control where acute tubular necrosis was observed. In the IPK experiments, CAP- and ENAL-treated kidneys had VR values that were significantly lower than those of ischemic controls.(ABSTRACT TRUNCATED AT 250 WORDS) |
8041144 | Glucocorticoids regulate glutaminase gene expression in human intestinal epithelial cells. | Glutamine is essential for intestinal metabolism and function, but its circulating and luminal availability to the mucosa may be diminished during critical illness. We hypothesized that glucocorticoids, which are produced in increased amounts during critical illness, accelerate mucosal glutamine metabolism. We studied intestinal glutamine utilization by examining the regulation of glutaminase in vitro, the enterocyte's principal enzyme of glutamine metabolism. Differentiated confluent human enterocytic cells (Caco-2 cells) were incubated with dexamethasone. Glutaminase activity was assayed and mRNA was extracted. Glutaminase transcripts were labeled with a 32P-labeled glutaminase cDNA probe, quantitated by phosphoimaging, and normalized to beta-actin. Dose- and time-response studies were performed. Dexamethasone-treated cells were also incubated with actinomycin D and cycloheximide. Dexamethasone (DEX) increased mucosal glutaminase activity by 45%, with maximal response at 12 hr. This increase was dose-dependent and was significant at doses of 1 and 10 microM. The dexamethasone-mediated increase in glutaminase activity was associated with a 40% increase in glutaminase mRNA. The DEX-induced increase in glutaminase activity was inhibited by actinomycin D and cycloheximide, indicating the requirement for de novo RNA and protein synthesis. Glucocorticoids stimulate glutamine metabolism in these human enterocytic cells by increasing the activity of glutaminase, a response that is preceded by an increase in gene transcription. This glucocorticoid-mediated increase in glutaminase activity may be a mechanism by which gut glutamine metabolism is maintained during critical illness when blood glutamine levels are diminished and food intake is often interrupted. |
8041143 | Alterations in macrophage signal transduction pathways mediate post-traumatic changes in macrophage function. | After injury, macrophage effector function diminishes while suppressor function increases. Protein kinase C (PKC), which initiates superoxide synthesis and phagocytosis, and phospholipase A2 (PLA2), which initiates eicosanoid metabolism, are key enzymes in cell signal transduction, which may mediate this change in cell function. The aim of this study was to investigate the effect of trauma on macrophage signal transduction. Swiss-Webster (CFW) mice (n = 210) were randomized to control or hindlimb amputation groups. Animals were sacrificed 24 hr after injury. Peritoneal macrophage function was assessed by measurement of superoxide anion (O2-), Fc, mannose-fucose-mediated phagocytosis, and PGE2 release. Membrane and cytosolic PKC activity were measured by radioimmunoassay in unstimulated and phorbol ester-stimulated cells. Membrane fatty acids and PLA2 activity were measured by thin-layer chromatography. Hindlimb amputation resulted in significantly decreased superoxide anion synthesis (0.7 +/- 0.2 nm vs 1.7 +/- 0.3 nmol/l/10(6) cells in controls, P < 0.01) and phagocytosis and a significant increase in prostaglandin E2 synthesis. This was associated with a shift in cell membrane metabolism with increased PLA2 activity, arachidonic acid turnover, and a significant reduction in PKC membrane translocation in response to phorbol ester. Together these data demonstrate an alteration in signal transduction pathways, which may account for the observed change in macrophage function after injury. |
8041142 | Adaptation of the Na+/glucose cotransporter following intestinal resection. | Following massive small bowel resection, the remaining intestine adapts to compensate for lost absorptive capacity. Although the Na+/glucose cotransporter plays a critical role in nutrient, fluid, and electrolyte transport in the small intestine, its role in adaptation following resection has not been defined. To examine this, we sought to determine whether there were changes in the expression of the Na+/glucose cotransporter, SGTL1, at the messenger RNA level. Lewis rats underwent either transection or 70% small bowel resection and reanastomosis. The animals were sacrificed at intervals following operation. Jejunum proximal to the anastomosis and ileum and colon distal to the anastomosis were harvested and analyzed for Na+/glucose mRNA by reverse transcriptase-polymerase chain reaction and Southern blot. Blots were semiquantitated by 32P labeling and standardized to beta-actin. Histologic sections and analysis of DNA, RNA, and protein content revealed hyperplastic changes. Following resection, mRNA for the Na+/glucose cotransporter in the jejunum increased significantly (P < 0.05) by 1 week and remained elevated. In the ileum, an almost fivefold increase occurred at 6 hr and persisted throughout the study (P < 0.05). The early response was greater in the ileum, distal to the reanastomosis, than that in the jejunum (P < 0.05). In contrast, there was no change in the small amount of transporter mRNA detected in the colon. These results suggest that, in addition to mucosal hyperplasia, the intestinal response to resection involves upregulation of transporter mRNA by the individual enterocyte. This transcriptional increase in the Na+/glucose cotransporter appears to be an early response by the intestine and may be important in maintaining overall intestinal transport capacity following resection. |
8041141 | Regulation of MAP kinase activity by growth stimuli in vascular smooth muscle. | Intracellular signaling pathways regulating vascular smooth muscle (VSM) cell growth and hypertrophy can be initiated by activation of receptor tyrosine kinases and/or protein kinase C (PKC). Mitogen-activated protein kinases (MAP kinases) are cytosolic serine/threonine kinases, proposed to act as a point of convergence for diverse growth factors utilizing these signaling pathways. The goals of this study were (1) to determine whether MAP kinase is expressed in cultured rat aortic VSM, (2) to assess the activation of MAP kinase by known proliferative and hypertrophic stimuli, and (3) to determine if stimulation of a PKC-dependent signaling pathway in these cells results in MAP kinase activation. MAP kinase activity was measured in cytosolic extracts of aortic VSM by quantifying myelin basic protein phosphorylation. Three peaks of activity were resolved chromatographically and identified as MAP kinase isoforms (MW 42, 44, and 46 kDa) by immunoblotting with antipeptide antibodies specific for MAP kinase. MAP kinase activity in quiescent growth-arrested cells (157 +/- 19 pmole 32P/min/mg) was markedly stimulated within 15 min by known mitogens (10% serum, 731 +/- 40 pmole 32P/min/mg; 40 ng/ml PDGF, 670 +/- 105 pmole 32P/min/mg; P < 0.01) and partially sustained for at least 90 min (serum, 606 +/- 34 pmole 32P/min/mg; PDGF, 323 +/- 59 pmole 32P/min/mg P < 0.05). Angiotensin II (AII, 0.1 microM) and a pharmacological PKC activator, phorbol 12,13-dibutyrate (PDB, 0.1 microM), are reported to be nonmitogenic hypertrophic stimuli in these cells. These stimuli transiently increased MAP kinase activity with a peak at 5 min (AII, 328 +/- 15 pmole 32P/min/mg; PDB, 592 +/- 41 pmole 32P/min/mg; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS) |
8041140 | Butyrate increases colonocyte protein synthesis in ulcerative colitis. | Butyrate promotes epithelial cell healing and improves symptoms when administered rectally in patients with distal ulcerative colitis (UC). It was hypothesized that butyrate may enhance healing in patients with UC by stimulating colonocyte proliferation and/or protein production. Mucosa from the descending colon was obtained from patients with UC (n = 5), Crohn's disease (n = 8), diverticulitis (n = 6), and cancer (normal tissue 10 cm from tumor; n = 10). Epithelial cells were isolated using dispase/collagenase and differential sedimentation and incubated for 4 hr at 37 degrees C with either Na butyrate (10 mM) or NaCl (10 mM). Protein synthesis was assessed by [14C]leucine incorporation and proliferation was determined with [3H]thymidine. Mean viability and purity were >88%. Spontaneous proliferation was significantly increased in UC when compared to diverticulitis and normal controls. Butyrate significantly increased protein synthesis in UC epithelial cells when compared to saline control. The therapeutic effects of butyrate in patients with UC may be due to its use by epithelial cells as a metabolic fuel to increase protein production and promote healing. |
8041139 | Remote tissue injury primes hepatocytes for nitric oxide synthesis. | Following trauma and tissue injury, patients frequently suffer infections and septic complications. Tissue injury is associated with the induction of the hepatic acute-phase response, but how this phenotypic expression by hepatocytes influences their subsequent response to endotoxin (lipopolysaccharide, LPS) or inflammatory cytokines is unknown. We have shown that both rat and human hepatocytes maximally express the enzyme-inducible nitric oxide synthase (iNOS) in response to a combination of LPS and the cytokines tumor necrosis factor (TNF), interferon-gamma (IFN-gamma), and interleukin-1. Furthermore, we have shown that the in vivo induction of the acute-phase response following tissue injury (hind limb turpentine injection) is not associated with hepatocyte iNOS expression. In this study, we show that the phenotypic change associated with the acute-phase response following tissue injury primes the hepatocyte to subsequently express iNOS in vitro in response to LPS alone as well as TNF and IFN-gamma. This expression of iNOS can be seen as early as 3 hr following the initial injury and lasts up to 24 hr. Early postinjury changes result in maximal expression following stimulation with TNF or IFN-gamma. Later (24 hr post-injury) changes reveal LPS to be the most potent inducer with as little as 0.01 microgram/ml LPS being required for iNOS mRNA expression. The in vivo correlate of tissue injury (turpentine injection) followed by sepsis (intraperitoneal LPS injection) resulted in a three- to fourfold rise in plasma levels of the stable end-products of nitric oxide production, nitrite, and nitrate (NO2- + NO3-), over levels seen in cases of sepsis alone.(ABSTRACT TRUNCATED AT 250 WORDS) |
8041138 | Gut failure and translocation following burn and sepsis. | Sepsis with multisystem organ failure is a major cause of morbidity and mortality in burns. We studied the anatomic, physiologic, and metabolic changes of gut mucosa as a normal barrier against sepsis and systemic inflammatory response after burn and sepsis in the chronic porcine model. Flow probes were placed on the mesenteric and hepatic arteries and portal vein. Catheters were placed in the pulmonary artery (Swan-Ganz), aorta, superior mesenteric, and hepatic veins. After 5 days, baseline data were collected and studied after a 40%, third degree burn. They were resuscitated with Ringer's lactate solution (Parkland formula). Eighteen hours later, Escherichia coli endotoxin (100 micrograms/kg) was administered. All animals were sacrificed after 30 hr. The data were compared to a group of sham animals. Following thermal injury the cardiovascular status was stable. Endotoxin administration decreased systemic vascular resistance index and mean arterial pressure, but increased cardiac index. Mesenteric blood flow, vascular resistance, and oxygen consumption showed a transient fall after endotoxin infusion with 20, 23, and 40% reduction, respectively. These changes were associated with a rise in plasma levels of conjugated dienes. The intestinal ornithine decarboxylase activity was elevated at the end of the experiment, evidence of gut repair. Gut bacteria translocated into mesenteric lymph nodes, spleen, and burn wounds in 50% of the animals. We concluded that bacterial translocation into mesenteric lymph nodes, spleen, and wound is due to gut mucosal failure after burn trauma and sepsis. These pathophysiologic changes may be the result of mesenteric ischemia and reperfusion injury. |
8041137 | Neutrophil depletion attenuates human intestinal reperfusion injury. | Intestinal ischemia/reperfusion injury (I/R) results from reactive oxygen metabolites generated by the xanthine oxidase system and activated neutrophils (PMN). In animal models, removing PMN from initial reperfusate has consistently decreased tissue injury. This experiment was designed to test this potential clinical treatment in human bowel subjected to I/R. The extent of reperfusion injury was assessed by measuring the activity of mucosal alkaline phosphatase (A phi), which is a specific marker of reperfusion injury. Human small intestine (n = 13) obtained at the time of organ harvest for transplantation was perfused for 60 min on an ex vivo perfusion circuit. Reperfusate consisted of autologous blood passed through a leukocyte filter (n = 6) or unfiltered blood (n = 7). Control intestine was sampled at harvest, after transport to the lab on ice (cold ischemia), and after 60 min warm ischemia. Mucosa was homogenized and assayed for A phi activity by cleavage of p-nitrophenyl phosphate. A phi activity (nmole/mg/min) was not decreased after either cold (774 +/- 37) or warm (753 +/- 40) ischemia compared to freshly harvested bowel (770 +/- 51). Both reperfused segments showed a significant decrease in A phi activity compared to controls (P < 0.05); however, reperfusion with leukocyte-filtered blood attenuated the decrease in enzyme activity compared to unfiltered blood (327 +/- 30 vs 506 +/- 25, P < 0.05), constituting an apparent reduction in injury of 35%. The observation that the severity of reperfusion injury was decreased by removal of PMN from the reperfusate demonstrates the efficacy of this strategy in human intestine for the first time. |
8041136 | Sequential insult enhances liver macrophage-signaled hepatocyte dysfunction. | Injury results in altered hepatocyte protein synthesis including the production of acute-phase reactants. Evidence suggests that these hepatocyte products regulate macrophage function; however, their role in liver macrophage-mediated hepatocyte dysfunction following a second insult is poorly characterized. We hypothesize that IL-6-stimulated hepatocyte products alter liver macrophage responses to lipopolysaccharide, contributing to enhanced hepatocyte dysfunction. To test this hypothesis, hepatocytes, obtained by liver collagenase digestion, were treated with rIL-6 (murine, 300 units/ml) for 24 hr, and then liver macrophages, obtained by perfusion and pronase digestion, were added to establish cocultures. Cocultures were then stimulated with endotoxin (LPS, Escherichia coli O111:B4, 10 micrograms/ml) and hepatocyte dysfunction was assessed by determining secretory protein synthesis ([35S]methionine labeling, trichloracetic acid precipitation, and SDS-PAGE) and energy metabolism [mitochondrial respiration using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) dye]. Cultures of hepatocytes alone stimulated with IL-6, LPS, or sequential IL-6 followed by LPS demonstrate no difference in total secretory protein synthesis or mitochondrial respiration. In contrast, hepatocyte-liver macrophage cocultures demonstrate significantly reduced total secretory protein synthesis following sequential IL-6 followed by LPS ([35S]methionine cpm x 10(3): control, 33.8 +/- 8.5; LPS, 25.8 +/- 6.3; IL-6/LPS, 15.7 +/- 6.4; P < 0.05 vs control). This effect is specific to IL-6 since sequential TNF-alpha followed by LPS did not result in significant suppression of secretory protein synthesis. One-dimensional SDS-PAGE of labeled coculture secretory proteins demonstrates qualitative changes following sequential insult in vitro compared to controls.(ABSTRACT TRUNCATED AT 250 WORDS) |
8041135 | Ischemic preconditioning preserves end-ischemic ATP, enhancing functional recovery and coronary flow during reperfusion. | The mechanisms by which ischemic preconditioning (IPC) protects against reperfusion (RP) injury are unknown. The purpose of this study was to relate IPC to postischemic mechanical function, vascular reactivity, and bioenergetics. Isolated perfused rat hearts were randomized to two groups. Control (CTRL) hearts underwent 25 min of global, 37 degrees C ischemia and 40 min RP. IPC hearts underwent 2.5 min ischemia and 10 min RP followed by 25 min ischemia and 40 min RP (RP40). Left ventricular developed pressure (DP) and coronary flow were continuously measured. 31P NMR spectra determined phosphocreatine and ATP concentrations in parallel hearts every 5 min. Results are means +/- SEM; n = 6/group. Significance was assumed for P < 0.05 by paired (within groups) and unpaired (between groups) t test. CTRL heart DP recovered to 35 +/- 4% of preischemic (PI) DP by RP40 (P < 0.001), while IPC heart DP reached 99 +/- 4% (P = NS vs PI; P < 0.001 vs CTRL). CTRL coronary flow recovered to only 75 +/- 3% of PI (P < 0.001) by RP40. IPC coronary flow exceeded baseline during RP (RP40 = 118 +/- 3%, P < 0.001 vs CTRL; P < 0.05 vs PI). After 25 min ischemia, CTRL heart ATP fell to 40 +/- 4% of PI (P < 0.001) while the IPC group fell to only 60 +/- 4% (P < 0.05 IPC vs CTRL; P < 0.001 vs PI). IPC preserves more end-ischemic ATP compared to CTRL hearts with a resultant improvement in mechanical function during reperfusion. Only preconditioned hearts preserve the adaptive mechanism(s) responsible for postischemic vasodilatation.(ABSTRACT TRUNCATED AT 250 WORDS) |
8041134 | Effect of angiotensin II on human vascular smooth muscle cell growth. | Inhibitors of the production of endogenous angiotensin II (A-II) can diminish the hyperplastic response produced by arterial injury in animals; however, a similar effect in humans has not been observed. To explain this discrepancy, we compared the effect of A-II on rat aortic smooth muscle cells (R-SMC) and smooth muscle cells derived from human saphenous veins (H-SMC). A-II (10-1000 nM) significantly increased the proliferative rate of R-SMC incubated in 10% serum, but a similar effect was not observed with H-SMC. Incubation of R-SMC for 24 hr with A-II (1 microM) produced a significant increase in cell size (7%) and protein production (18%), whereas no hypertrophic response was noted in H-SMC exposed to A-II. In neither R-SMC nor H-SMC did A-II, in any concentration, induce cell migration. Stimulation of R-SMC with A-II resulted in tyrosine phosphorylation of five proteins (approximately 120, approximately 108, approximately 68, 45, 42 kDa). The 42- and 45-kDa proteins, which we have previously identified as mitogen-activated protein kinases (MAP-K), remained phosphorylated for 1 hr. In H-SMC, only MAP kinases were tyrosine phosphorylated, but with less intensity than in R-SMC, and only for 20 min. In protein kinase C-depleted SMC, tyrosine phosphorylation of MAP kinase was inhibited in both cell types. A-II produced hypertrophy and hyperplasia of R-SMC, but not H-SMC. Differences in intracellular signaling might account for these disparate effects.(ABSTRACT TRUNCATED AT 250 WORDS) |
8041133 | The extracellular matrix of the fetal wound: hyaluronic acid controls lymphocyte adhesion. | Adhesive interactions between lymphocytes and components of the extracellular matrix (ECM) within a wound environment play a crucial role in determining the inflammatory response following tissue injury. In fetal wounds the extracellular matrix is composed predominantly of hyaluronic acid. Within this environment the inflammatory reaction as a result of injury is minimal. We propose that this lack of an inflammatory cell response in the fetal wound is due to the high levels of hyaluronic acid within the ECM and the inability of lymphocytes to adhere to this matrix component. Therefore, we examined the adhesive properties of fetal lymphocytes to fibronectin, vitronectin, collagen types I, III, IV, V, and hyaluronic acid--ECM components involved in fetal and adult wound environments. Fetal lymphocytes from both spleen and thymus demonstrated significant binding capabilities to fibronectin, vitronectin, and collagen types I and III. No intrinsic binding capabilities were detected to hyaluronic acid. Adhesion was not affected by the addition of IL-1, IFN-gamma, or phorbol dibutyrate. The inability of lymphocytes to adhere to hyaluronic acid helps to explain the lack of inflammation found in fetal wounds and serves to demonstrate the importance of ECM-lymphocyte interactions in determining the inflammatory response during fetal wound healing. |
8041132 | Deferoxamine given at reperfusion improves function of the cold-stored rat heart. | In this study deferoxamine (DF), a strong iron chelator, was administered either before storage or during reperfusion, in an attempt to inhibit the iron-dependent hydroxyl radical production and improve the functional recovery of the cold-stored/reperfused cardiac explant. Excised rat hearts were flushed with Krebs-Henseleit buffer (KHB), arrested with a cardioplegic solution, CP11-EB, with or without DF, and immersion stored in CP11-EB at 0 degree C for 16 hr. To assess function, the stored hearts were reperfused in the working mode with KHB for 30 min. Experimental groups included: (i) DF treatment during prestorage flush [CP11-EB + 0.01 mM (n = 5), 0.05 mM (n = 13), 0.1 mM (n = 5), 0.2 mM (n = 5), or 0.75 mM DF (n = 5)]; (ii) DF treatment during reperfusion [KHB + 0.3 mM (n = 5), 0.6 mM (n = 7), 0.75 mM (n = 11), 1.0 mM (n = 6), 1.5 mM (n = 4), or 2.5 mM DF (n = 7)]; and (iii) untreated group (n = 8) received no DF during flush or reperfusion. Function of unstored hearts (n = 7) including aortic flow (AF, 54.6 +/ 2.6 ml/min); cardiac output (CO, 76.5 +/- 3.3 ml/min), systolic pressure (SP, 135.7 +/- 1 mm Hg), diastolic pressure (DP, 70.7 +/- 3.8 mm Hg), and work (96.7 +/- 6.4 g-meter/min) served as controls. Functional recovery of the untreated group was AF, 59%; CO, 58%; SP, 71%; DP, 73%; work, 41% of control values. DF treatment at any dose during the initial flush did not improve functional recovery.(ABSTRACT TRUNCATED AT 250 WORDS) |
8041131 | Changes in oxygen consumption relative to oxygen delivery in endotoxemic dogs given adrenergic agents. | Adrenergic agents (AAs) have been used in critically ill patients to increase oxygen delivery (DO2). Associated parallel increases in oxygen consumption (VO2) have been noted and are thought to represent improved tissue oxygen utilization at supraphysiologic levels of DO2. We hypothesize that the increase in VO2 associated with the use of AAs in septic animals is secondary to direct, obligate, metabolic effects of the agents themselves. In this study, mongrel dogs were anesthetised, paralyzed, and had minimum temperature maintained on a warming blanket. Pulmonary and systemic hemodynamics were monitored. DO2 was calculated, while VO2 was measured directly with a metabolic cart. All dogs were given an Escherichia coli challenge and a colloid fluid resuscitation. Two hours after the onset of endotoxemia, baseline values were obtained, followed by four progressively larger doses of saline, dobutamine, or dopamine. At each dose there was a 40-min stabilization period and a 20-min measurement of hemodynamics and VO2. Data were analyzed using analysis of variance with a Scheffe's S test. P values of < 0.05 were considered significant. The control group slowly decreased VO2 during the 6-hr experiment to 73% of baseline. Dobutamine increased VO2 to 119% of baseline (31% above control) and dopamine to 111% of baseline (28% over control). We conclude that adrenergic agents cause a significant increase in whole body VO2 at moderate doses in septic dogs. It is likely, therefore, that the "pathologic" relationship between VO2 and DO2 described in critically ill patients is partially due to the direct metabolic effects of AAs. |
8041130 | Use of donor serum to prevent passive transfer of hyperacute rejection. | Organ transplantation in presensitized recipients continues to be contraindicated for heart and kidney recipients due to the risk of hyperacute rejection, which has no known treatment at this time. We tested whether donor serum, which contains soluble MHC class I antigen, is able to neutralize the effect of anti-donor antibody in the recipient and prevent hyperacute or accelerated rejection. A rat model of passive immunization was used to test the role of anti-donor antibody in hyperacute rejection. Seven of 10 recipients of hyperimmune serum (HyS), derived from Lewis rats (RT1l) following 3 ACI (RT1a) skin grafts, developed hyperacute or accelerated rejection. Intravenous injection of ACI serum prior to the HyS administration prevented hyperacute rejection in all recipients tested. When third-party (Wistar-Furth, RT1u) serum was given to Lewis rats injected with HyS, hyperacute rejection was not abrogated. When examining the mechanism of this effect, a simple antibody blocking phenomenon was found to be unlikely since flow cytometry analysis showed that ACI serum needed to be present at > or = 256-fold excess compared to HyS to block anti-ACI antibody binding to RT1.Aa+cells by 50%. We tested whether the RT1.Aa class I antigen in ACI serum had other biologic properties that resulted in the prolonged graft survival. However, removal of RT1.Aa antigen from ACI serum prior to use in the passive transfer model did not abrogate the graft prolongation observed previously. These data suggest that components of donor serum other than MHC class I antigen may be useful for preventing the antibody-mediated component of hyperacute rejection. |
8041129 | Effect of glutamine and chemotherapy on protein metabolism in tumor-bearing rats. | Supplemental glutamine prevents gut atrophy and enhances muscle protein synthesis in septic rats. This study investigated the effect of glutamine administration and mitomycin C treatment on protein turnover in tumor-bearing rats. AH109A rat ascites hepatoma cells (2 x 10(6)) were subcutaneously implanted in the back of male Donryu rats (n = 32, body weight 150-200 g) on Day 0. The animals were then fed rat chow ad libitum for 10 days. On Day 10, the rats were catheterized for TPN and randomized into four groups according to diet and treatment. The groups were: (i) standard total parenteral nutrition (STPN) + saline; (ii) glutamine-supplemented TPN (GTPN) + saline; (iii) STPN+mitomycin C (MMC); (iv) GTPN+MMC. GTPN was isocaloric (250 kcal/kg/day) and isonitrogenous (1.5 gN/kg/day) with STPN. The animals were maintained on TPN for 5 days and received mitomycin C (0.5 mg/kg) via the catheter every day. On the fifth day of TPN, [1-14C]leucine was given via a 5-hr continuous infusion (2.0 microCi/hr/rat) to determine the fractional synthesis rate of muscle, gut mucosa, liver, and tumor. Also, endogenous leucine production (not equal to whole body protein breakdown rate) was calculated. Body weight loss during TPN was reduced with GTPN. GTPN enhanced muscle FSR in untreated animals (STPN: 10.8 +/- 8.7%/day vs GTPN: 14.7 +/- 0.6%/day, P < 0.05) and in mitomycin C-treated animals (STPN+MMC: 9.6 +/- 0.9%/day, GTPN+MMC: 12.0 +/- 0.8%/day, P < 0.05). The whole body protein breakdown rate was reduced with GTPN. Mitomycin C reduced the mucosal fractional synthesis rate and GTPN did not prevent this reduction.(ABSTRACT TRUNCATED AT 250 WORDS) |
8041128 | Intragraft expression of messenger RNA for interleukin-6 and tumor necrosis factor-alpha is a predictor of rat small intestine transplant rejection. | Detection of rejection after small intestine transplantation (SIT) is difficult, relying largely on histopathology. The purpose of this study was to determine if the intragraft expression of messenger RNA (mRNA) for interleukin-2 receptor (IL-2R), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF) correlated with rejection in a unidirectional, heterotopic rat SIT model. Graft samples were obtained on postoperative day (POD) 3, 5, 7, 8, 9, 10, 12, and 14. After staining, formalin-fixed samples were blindly evaluated for rejection. Reverse transcriptase polymerase chain reaction (rtPCR) using primers specific for beta-actin, IL-2R, IL-6, and TNF was performed on liquid nitrogen-frozen samples. Semiquantitation was accomplished using radionuclide incorporation and beta-scintillation counting. Intestinal histopathology in all isografts (ISO) and POD 3 allografts (ALLO) was normal. Rejection progressed in ALLO from mild on POD 5 to severe by POD 8. rtPCR analysis revealed constitutive expression of IL-2R mRNA in both ISO and ALLO. TNF and IL-6 demonstrated significant increases in mRNA expression in ALLO compared to ISO beginning on POD 5. In summary, intragraft expression of IL-2R mRNA demonstrated late up-regulation in ALLO which did not correlate with rejection. TNF and IL-6 mRNA expression predicted rat SIT rejection. rtPCR analysis of TNF and IL-6 may serve as a useful diagnostic adjunct for rat SIT rejection. |
8041127 | Multiple platelet surface receptors mediate platelet adhesion to surfaces coated with plasma proteins. | The interactions between platelets and plasma proteins previously shown to adhere to biomaterials were evaluated, using monoclonal antibodies (mAbs) against specific platelet surface glycoprotein (GP) receptors. Purified 51Cr-labeled human platelets in plasma-free medium were incubated with each of the following antibodies: mAb 10E5 [anti-GP IIb/IIIa; fibrinogen, von Willebrand factor (vWF), and fibronectin receptor]; mAb 6D1 (anti-GP Ib-IX; vWF receptor); mAb IV.3 (anti-Fc gamma RII; IgG receptor); polyclonal antiserum A108 or mAb BIIG4 (anti-GP Ic-IIa; fibronectin receptor). Antibody-treated platelets were added to microtiter wells coated with fibronectin, fibrinogen, vWF, IgG, vitronectin, albumin, or platelet-poor plasma (PPP). 51Cr-labeled platelet adhesion to matrix proteins was expressed as a percentage of that measured on PPP-coated surface. Platelets adhered to fibrinogen, fibronectin, vWF, or IgG immobilized on polystyrene. Limited binding to either vitronectin or albumin was detected. Binding to fibrinogen and IgG was blocked by mAb 10E5. Binding to IgG was also blocked by mAb IV.3. Binding to fibronectin, reduced in the presence of mAb 10E5, mAb BIIG4, or the polyclonal antiserum A108 alone, was further reduced by combined 10E5 and BIIG4 or 10E5 and A108. Neither mAb 10E5 nor 6D1 alone blocked adhesion to vWF; however, the combination of 10E5 and 6D1 significantly reduced platelet adhesion to this matrix. Finally, platelet adhesion to the plasma-coated surface was reduced by mAbs 10E5 and BIIG4. These results indicate that multiple adhesion receptors can mediate platelet adhesion to matrix proteins immobilized on surfaces. |
8041126 | The functional and morphological consequences of balloon catheter injury in veins. | Endovascular procedures are now used to treat occlusive arterial and venous diseases. However, after arterial catheter injury, intimal hyperplasia develops and there is altered endothelial and smooth muscle cell vasoreactivity of the vessel segment. This study examines the morphology and vasoreactivity of veins which have undergone balloon catheter injury. Under direct vision, 22 jugular veins of 11 New Zealand White rabbits were catheterized with a Fogarty balloon catheter (4Fr, three passes, 0.75 ml H2O inflation). Ten uninstrumented jugular veins from 5 additional animals were used as controls. Immediately after balloon injury, 10 jugular veins were harvested. Scanning electron microscopy of these vessels confirmed complete endothelial denudation and no in vitro endothelium-dependent relaxation was observed. After 28 days, 12 veins were harvested. There were no occlusions. Histologically, the 28-day balloon-injured veins had an almost confluent endothelium. However, there was medial hypertrophy but no development of intimal hyperplasia. There were no significant changes in the contractile responses of the balloon-injured veins after 28 days to norepinephrine. Bradykinin and histamine responses were markedly attenuated. Following bradykinin precontraction, balloon-injured veins showed diminished acetylcholine sensitivity with a reduced maximal response, and a small decrease in serotonin sensitivity with a markedly decreased maximal response. In contrast, there was an increased sensitivity in response to sodium nitroprusside without a change in maximal response in precontracted balloon-injured veins. This study shows that after 28 days venous balloon injury does not induce the development of intimal hyperplasia but does reduce overall endothelial dependent relaxation (acetylcholine- and serotonin-mediated) with increased sensitivity to endothelial independent relaxation (sodium nitroprusside-mediated). These findings would suggest that when compared to arterial balloon injury, venous balloon injury does not carry the same histological and vasoconstrictive sequelae but does demonstrate similarly impaired endothelial cell function. |
8041125 | Systemic hypertension and hypercholesterolemia in vein grafts: effects on the function and morphology of experimental vein grafts. | Hypertension and hypercholesterolemia are known risk factors for the development of atherosclerosis and are considered to influence the development of vein graft intimal hyperplasia. This study examines the effect of hypertension (two-kidney, one-clip model for 8 weeks) and hypercholesterolemia (1% cholesterol diet for 8 weeks) individually and in combination on the formation of intimal hyperplasia and the vasomotor function of vein grafts. Forty New Zealand White rabbits underwent a carotid vein bypass graft. Ten were controls, 10 were hypertensive, 10 were hypercholesterolemic, and 10 had both hypertension and hypercholesterolemia. Hypertension and/or hypercholesterolemia were present for 4 weeks prior to and for 4 weeks after surgery. All vein grafts were harvested at 4 weeks postoperatively for histology (n = 6) or contractility studies (n = 4). Compared to controls, hypercholesterolemia increased intimal but not medial thicknesses of the vein grafts and enhanced smooth muscle cell contractility. Hypertension did not increase vein graft intimal or medial thicknesses but did augment vein graft contractility compared to controls. Hypertension with hypercholesterolemia increased intimal and medial thicknesses and enhanced vasoreactivity in vein grafts. The results show that hypertension influences the vasoreactivity but not the development of intimal hyperplasia in vein grafts. When hypertension is combined with hypercholesterolemia, there is both an increase in the medial thickness and an attenuation of vasomotor function compared to hypercholesterolemia alone, although there is no further increase in intimal hyperplasia formation. Therefore, this study suggests that the combination of both atherogenic risk factors does not act synergistically in promoting either the formation of intimal hyperplasia or vasomotor dysfunction in vein grafts. |
8041124 | Dual structural and functional phenotypes of the porcine aortic valve interstitial population: characteristics of the leaflet myofibroblast. | The cellular properties of semilunar cardiac valve leaflets may be more complex than previously assumed. In particular, the cells of the leaflet matrix which are likely critical to proper cusp function are a poorly described population to date. We hypothesized that, similar to the matrix cells of atrioventricular valves, aortic valve leaflet interstitial cells (AoLIC's) possess characteristics of both fibroblasts (matrix secretion) and smooth muscle cells (contraction). Porcine AoLIC's were structurally examined for contractile and stress fiber protein assemblies using transmission electron microscopy and immunocytochemistry. Contractile function in response to vasoactive stimuli was directly assessed using AoLIC's cultured on flame-polymerized silicone, with cell contraction identified by the appearance of wrinkles in the substratum after challenge with each agent. The structural analyses showed cellular microfilaments were often organized into various contractile arrangements including polygonal networks, and that AoLIC's are rich in smooth muscle-specific alpha-actin. Incomplete basal laminae often associated with myofibroblasts were observed. Contraction experiments indicated a responsivity of similar latency, but variable peak and duration to 10(-7) M L-epinephrine, 3.2 x 10(-7) M angiotensin II, 110 microM carbachol, 50 mM KCl, 3.2 x 10(-7) M bradykinin, 110 microM isoproterenol, and 5 x 10(-7) M endothelin I. Soluble and insoluble matrix secretion was confirmed with FITC-conjugated monoclonal antibodies to chondroitin sulfate, fibronectin, and prolyl-4-hydroxylase. These data show that the AoLIC's are best designated as myofibroblasts. The unusual features of the myofibroblast may be central to lifelong aortic leaflet durability. |
8041123 | Distribution of cell adhesion molecules in decidua of early human pregnancy. An immunohistochemical study. | The aim of the study was to investigate human decidua for cell adhesion molecules involved in interactions between the various different maternal and fetal cell populations, homing of the unusual intradecidual population of CD56+ lymphocytes, and organization of the decidual extracellular matrix. First trimester human decidua from normal pregnancies was investigated immunohistochemically with antibodies against integrin subunits (alpha 1-6, alpha L, alpha M, alpha X, alpha IIb, alpha V, beta 1, beta 3, and beta 4), platelet-endothelial cell adhesion molecule, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and L-selectin. Endometrial glands stained for alpha 1, alpha 2, alpha 3, alpha 5, alpha 6, alpha V, beta 1, beta 3, and beta 4, and stromal cells for alpha 1, alpha 3, alpha 5, alpha 6, alpha V, beta 1, beta 3, ICAM-1, and VCAM-1. Endothelium stained for alpha 1, alpha 2, alpha 3, alpha 4, alpha 5, alpha 6, alpha V, alpha IIb, beta 1, beta 3, and beta 4; platelet-endothelial cell adhesion molecule and ICAM-1 also were found on the endothelium of a large number of blood vessels of all types, and VCAM-1 on the endothelium of a moderate number of arterioles and venules, and a few capillaries. Weak staining for E-selectin was seen in a moderate number of arterioles and venules. Large numbers of lymphocytes stained for alpha 4, alpha L, alpha M, alpha X, beta 1, and moderate or small numbers for alpha 1, alpha 3, alpha 5, alpha v, beta 3, platelet-endothelial cell adhesion molecule, ICAM-1, and L-selectin. Decidual stromal cells, like endometrial glands and endothelium, express integrins that bind basement membrane components. These integrins represent the basis for the formation of the pericellular basement membrane of these cells. They also bind certain glycoproteins that support outgrowth and attachment of the trophoblast in vitro. Vitronectin-binding integrins on endometrial glands, stromal cells, and endothelium may be involved in adhesion of the trophoblast through vitronectin on its surface. From our findings and published data it seems that adhesion of alpha 1 beta 2 (leukocyte function-associated antigen-1) on lymphocytes to ICAM-1 on the endothelium plays the most important role in the migration of CD56+ lymphocytes from the peripheral blood into the decidua. The expression of several beta 1 (VLA) integrins on lymphocytes suggests that these cells are activated, and, like the expression of ICAM-1 and VCAM-1 on stromal cells, probably contributes to their retention in the decidual stroma. |
8041122 | Migration of ganglion cell precursors in the ileoceca of normal and lethal spotted embryos, a murine model for Hirschsprung disease. | Dopamine-beta-hydroxylase-nlacZ transgenic mice are useful for studies of enteric neurodevelopment. Expression of the transgene provides a histochemical marker for neuroblasts in wild-type embryos and embryos homozygous for the lethal spotted (ls) allele that are born with aganglionosis coli and serve as a model for the human birth defect, Hirschsprung disease. Neuroblasts, derived from the vagal neural crest, colonize the gut in a cranial-to-caudal manner. However, migration of neuroblasts in ls/ls gut is impaired when neuroblasts reach the ileocecal junction and attempt to colonize the large intestine. To learn more about neuroblast migration through this specific region of the intestinal tract, a detailed light and electron microscopic study of neuroblast colonization of the developing ileoceca from wild-type, ls/+, and ls/ls embryos was conducted. The ileoceca from wild-type, ls/+, and ls/ls, dopamine-beta-hydroxylase-nlacZ embryos (E10.5-E13.5) were treated with a histochemical substrate for the transgene product and examined by light and electron microscopy. Five stages of ileocecal development were defined based on distinctive gross, light, and electron microscopic features. At each stage, neuroblasts had different ultrastructural features than other mesenchymal cells. Initial colonization of the colon was different from other parts of the gut, in that a string of "pioneer" neuroblasts populated the mesenteric border of the proximal colon before circumferential invasion. Subsequently, neuroblasts were arranged in intersecting linear groups of contiguous cells that radiated around the cecum and proximal colon. In ls/ls embryos, transition from neuroblast extension along the mesenteric border to cecal invasion was delayed profoundly. However, the ultrastructural features of neuroblasts and adjacent mesenchyme were indistinguishable in ls/ls and wild-type embryos. This study supports the hypothesis that impaired migration of neuroblasts in ls/ls embryos is not limited to the presumptive aganglionic segment, but begins at the ileocecal junction. Migration of neuroblasts from the ileum into the proximal colon follows a different pattern than movement of neuroblasts through the small intestine. The biological bases for these differences may account for the defects observed in ls/ls mice and/or may affect the pathogenesis of human Hirschsprung disease. |
8041121 | Epstein-Barr virus-associated gastric carcinoma and Epstein-Barr virus infection of the stomach. | Epstein-Barr virus (EBV) has been found to be associated with a type of gastric carcinoma (EBVaGC). However, many questions remain unanswered, such as epidemiology, and pathologic features of EBVaGC and the significance of EBV in the genesis of EBVaGC. Gastric carcinoma and non-neoplastic mucosa were evaluated to reveal the following issues: the incidence of EBVaGC in Japanese population, pathologic features and EBV genotype, clonality, and gene-expression in EBVaGC, localization of EBV in non-neoplastic stomach, and serum titer of anti-EBV antibodies in EBVaGC-carrying patients. Using PCR and EBER1 in situ hybridization, EBVaGC (definitely amplifiable EBV-DNA and positive EBER1-signal in the nuclei of carcinoma cells) was found in 8 of 72 gastric carcinomas (11%). The dominant genotype of EBV was type A (7/8), with type C (6/8), and F (8/8) restriction enzyme polymorphism, which are the predominant type of EBV found in throat washing of the general population in Japan. EBVaGC was found in the cardia (4/8) or body (4/8) of the stomach, and consisted of 7 advanced and 1 intramucosal carcinoma. By Southern blot analysis of EBVaGC hybridized with right- and left-side probe adjacent to the terminal repeats, EBV was present in a monoclonal episomal form in all of the EBVaGC. EBVaGC lacked expression of EBNA2 (0/8) and LMP1 (0/8) by immunocytochemistry. In non-neoplastic mucosa, EBER1 signal was identified in the infiltrating lymphocytes and shedding epithelial cells predominantly in fundic gland mucosa of patients with EBVaGC (8/8). Patients with EBVaGC showed high titers of anti-VCA IgG (8/8), anti-VCA IgA (2/8) and anti-EA IgG (7/8) antibodies just before surgery. EBV may infect the surface epithelium of the stomach through the reactivated EBV-carrying lymphocytes. EBV may be a factor initiating EBVaGC. Anti-EBV antibodies or EBER1 in situ hybridization may help to identify patients at high risk for EBVaGC. |
8041120 | p53 mutations are confined to the comedo type ductal carcinoma in situ of the breast. Immunohistochemical and sequencing data. | Mutations in the p53 tumor suppressor gene have been identified in breast and many other carcinomas. It is not clear, however, when these mutations occur during breast carcinogenesis. Overexpression of 53 protein has been reported in some ductal carcinoma in situ (DCIS) lesions. To further study the overexpression of p53 in DCIS of the breast and correlate these findings with changes at the molecular level, we performed p53 immunostaining and direct sequencing in noncomedo and comedo DCIS. Archival blocks were obtained on cases of noncomedo DCIS, (including encysted, noninvasive papillary carcinoma) and comedo DCIS. Immunohistochemical staining with the p53 antibody DO7 was performed on all cases. Polymerase chain reaction (PCR) amplification of exons 5, 6, and 7 of the p53 gene was performed and the PCR products were directly sequenced. Four comedo DCIS cases that were p53 immunopositive were further screened for p53 mutations by PCR/single strand conformation polymorphism in exons 8 and 9 of the p53 gene. One of these cases showing a mobility shift was directly sequenced. We examined 39 lesions including comedo DCIS (N = 12) and noncomedo DCIS (N = 27), the latter including 17 encysted noninvasive papillary carcinomas. Immunostaining with DO7 was positive in 4 of 12 comedo DCIS lesions (33%) while all noncomedo lesions including encysted noninvasive papillary carcinomas were negative. Direct sequencing of PCR products confirmed wild-type DNA in exons 5 and 6 in all noninvasive papillary carcinomas, 3 randomly selected noncomedo DCIS lesions, and 4 p53 antibody-positive comedo DCIS lesions. In these latter 4 cases, wild-type DNA sequences were preserved in exon 7 for all cases. A single case had a conformational shift in exon 8 within the four cases screened in exons 8 and 9. Direct DNA sequencing of this exon revealed a G to A point mutation resulting in an arginine-to-histidine substitution at codon 273 of the protein. Our results suggest that mutant p53 protein accumulation in preinvasive lesions is limited to comedo (high grade) DCIS and that p53 positivity by immunohistochemistry does not correlate in all cases with specific p53 mutations in exons 5 to 9, the most highly conserved regions of this gene. |
8041119 | Quantitation of DNA topoisomerase II alpha messenger ribonucleic acid levels in a small cell lung cancer cell line and two drug resistant sublines using a polymerase chain reaction-aided transcript titration assay. | We have modified a polymerase chain reaction (PCR)-aided transcript titration assay (1) in order to allow quantitation of low amounts of DNA topoisomerase II alpha mRNA in small RNA samples. The titration assay was used to quantitate the amount of DNA topoisomerase II alpha mRNA in a human small cell lung carcinoma cell line, GLC4 and its drug-resistant sublines, GLC4/ADR and GLC4/CDDP. These cell lines show differences in DNA topoisomerase II alpha protein level and DNA topoisomerase II enzyme activity. To validate the titration assay, the results were compared with the results of a DNA topoisomerase II enzyme activity assay and DNA topoisomerase II alpha northern and western blotting assays. Using the titration assay, we were able to quantitate DNA topoisomerase II alpha mRNA on a picogram level starting with less than 1 micrograms of total RNA/cell line. GLC4/ADR showed a markedly decreased DNA topoisomerase II alpha mRNA level that seemed to be unchanged in GLC4/CDDP when compared with the parental cell line. The results obtained with this assay are confirmed by the western blot data and are not in contradiction with the northern blot results obtained for the three cell lines. The DNA topoisomerase II alpha titration assay is a highly sensitive new technique to study the role of DNA topoisomerase II alpha in drug resistance and may help to identify cancer types and patients most likely to respond to DNA topoisomerase II targeted drugs. The decrease in DNA topoisomerase II alpha protein level and DNA topoisomerase II activity in GLC4/ADR may result from transcriptional down regulation of DNA topoisomerase II alpha. |
8041118 | A subgroup of murine monoclonal anti-deoxyribonucleic acid antibodies traverse the cytoplasm and enter the nucleus in a time-and temperature- dependent manner. | The capacity of lupus autoantibodies to enter living cells and bind to molecules for which they have intrinsic affinity is not well appreciated. In previous studies, we identified a subgroup of three murine monoclonal IgG anti-DNA antibodies, derived from lupus-prone MRL-lpr/lpr mice, that localized within nuclei of cells in multiple organs and induced functional perturbations, in vivo, after passive transfer to normal mice. To examine the mechanisms of this phenomenon, we now extend these observations, using the same monoclonal anti-DNA antibodies and cultured cell lines. Multiple experimental approaches were utilized to track nuclear localization of anti-DNA antibodies, including direct immunofluorescence, confocal microscopy and immunoelectron microscopy. The requirements for nuclear localization were further evaluated quantitatively, in nuclei isolated from co-cultures of cells and 125I-Ig, under varying experimental conditions. Nuclear localization was observed with the same subset of anti-DNA antibodies that localized within nuclei in vivo; it was dependent on the antigen-binding region of the molecule; and it was not found with other anti-DNA antibodies. At progressive intervals, the Ig were observed: at the cell surface, within the cytoplasm, clustered at the nuclear pore, and within the nucleus. Nuclear localization of Ig was found to be a time- and temperature- dependent process, specific for a subset of anti-DNA antibodies and dependent on the antigen binding region of the Ig. This is the first demonstration that monoclonal autoantibodies can traverse both the cell and nuclear membranes to localize within the nuclei of cultured cells. Furthermore, nuclear localization of Ig was regulated in a manner analogous to that of other large cytoplasmic proteins that enter the nucleus. This confirms and extends our results using the same antibodies in whole animals, and it provides the basis to further examine the underlying mechanisms and consequences of this phenomenon. |
8041117 | Ultrastructural localization of a fluorinated bile salt in hepatocytes. | Interactions of bile salts with hepatocellular organelles are critical for the formation of bile, yet these interactions remain poorly characterized. We present a novel approach for visualizing bile salts at the ultrastructural level within hepatocytes, using a unique fluorinated bile salt conjugate and electron energy loss spectroscopy. Isolated rat hepatocytes were incubated for 5 and 20 minutes with the 2-fluoro-beta-alanine (FBAL) N-acyl amidate conjugate of cholic acid (C-FBAL, 50 microM). FBAL is a byproduct of hepatic 5-fluorouracil catabolism, and when conjugated to cholic acid is excreted into bile in a manner similar to the naturally occurring N-acyl amidates of bile salts. Cells were subjected to rapid cryofixation and automated freeze-drying followed by vapor-phase fixation using the LifeCell system, thus avoiding exposure to the leaching action of liquid fixatives. After resin infiltration, the cellular distribution of fluorine was determined in ultrathin sections with a Zeiss CEM902 electron microscope equipped for electron energy loss spectroscopy. Fluorine was detected primarily in association with intracellular membranes, particularly membranes of the endoplasmic reticulum (p < 0.05 at 20 minutes by morphometric analysis). Fluorine also was detected in association with membranes of the Golgi apparatus. The fluorine signal was confirmed by serial spectra of cell regions containing these organelles (p < 0.01), but was not detectable in the free cytosol, mitochondria or extracellular medium, nor in hepatocytes not exposed to C-FBAL. We conclude that cryofixation and freeze-dry processing followed by electron microscopy with electron energy loss spectroscopy is a valuable technique for examining intracellular processing of bile salts. Our results suggest that bile salts localize to the membranes, but not lumena, of organelles during hepatocyte exposure to bile salts, calling into question the proposed role for vesicular transport of bile salts within hepatocytes. |
8041116 | Roles of growth factors and of tumor necrosis factor-alpha on liver cell proliferation induced in rats by lead nitrate. | A single intravenous injection of lead nitrate to rats induces a synchronized wave of hepatocyte proliferation without accompanying liver cell necrosis. However, the mechanism of the mitogenic effect of lead nitrate is not known, and whether hepatocyte growth factor (HGF), transforming growth factor-alpha (TGF-alpha), and transforming growth factor-beta 1 (TGF-beta 1) play any role in it have not been investigated. These growth factors have indeed been shown to provide either positive or negative stimuli for liver cell regeneration after partial hepatectomy or liver cell necrosis. Moreover, there are reports showing that administration of non-necrogenic doses of tumor necrosis factor-alpha (TNF-alpha) to rats lead to an enhanced proliferation of hepatocytes and liver nonparenchymal cells. Lead is known to sensitize animals to lethal effects of bacterial lipopolysaccharides (LPS), suggesting that lead nitrate may modify the production of TNF-alpha in response to endogenous LPS of intestinal origin. An enhanced production of TNF-alpha could therefore be involved in the mitogenic action of lead nitrate. We investigated first whether a single intravenous dose of lead nitrate (100 mumole/kg) to rats modifies the production of HGF, TGF-alpha, and TGF-beta 1, by examining the steady-state level of their mRNA in the liver by Northern blot analyses. The response of rats given lead nitrate to various doses of LPS was next evaluated to determine whether lead-treated rats have an enhanced sensitivity to LPS. Finally, the level of TNF-alpha mRNA was examined in the liver of rats at various time periods after a single injection of lead nitrate. No changes were observed in the liver levels of mRNAs for HGF, TGF-alpha, and TGF-beta 1 at various time intervals after a single injection of lead nitrate. All rats given only single injections of LPS up to 100 micrograms survived. However, lead nitrate-treated rats tolerated LPS at dosages of only 6 micrograms. The liver of control rats showed a single 1.6 kb TNF-alpha transcript, whereas 1.8-kb transcripts were seen at 1 hour after lead nitrate injection, and persisted for 12 hours. The 1.8 kb TNF-alpha transcript was also present in the spleen of control rats, and its expression was enhanced in lead nitrate-treated rats. Stimulation of hepatocyte proliferation induced by lead nitrate was not accompanied by changes in liver levels of HGF, TGF-alpha, or TGF-beta 1 mRNA. Lead nitrate, however, enhanced expression of TNF-alpha at a time preceding the onset of hepatocyte DNA synthesis, indicating that TNF-alpha may trigger the lead nitrate-induced proliferation of hepatocytes. |
8041115 | On the analysis of the pathophysiology of Chediak-Higashi syndrome. Defects expressed by cultured melanocytes. | The Chediak-Higashi syndrome (CHS) is a disorder that affects the synthesis and/or maintenance of storage/secretory granules in various types of cells. Lysosomes of leukocytes and fibroblasts, dense bodies of platelets, azurophilic granules of neutrophils and melanosomes of melanocytes are generally larger in size and irregular in morphology, indicating that a common pathway in storage organellogenesis is affected in patients with CHS. A pure line of melanocytes has been established using a 2 cm2 shave biopsy from a child with CHS. This 4-week-old male patient had oculocutaneous albinism and expressed neutropenia, impaired platelet function, and no natural killer cell activity. The cultured CHS melanocytes were analyzed for cell biological and biochemical aberrancies. Cultured melanocytes demonstrated some large and/or complexed melanosomes that resembled those observed in melanocytes from ultrastructural sections of the biopsy. Cytoplasmic localization of tyrosinase, tyrosinase-related protein-1 and granulophysin (a 40 kilodalton membrane protein originally identified as a component in dense bodies of platelets) demonstrated a prominent perinuclear accumulation. The basal synthesis of melanin and the activity levels of tyrosine hydroxylase, dihydroxyphenylalanine (DOPA) oxidase, or DOPAchrome tautomerase were comparable to control Caucasian melanocytes in culture. However, melanin synthesis as well as the catalytic activities of tyrosinase were not dramatically upregulated in CHS melanocytes by the addition of isobutyl methylxanthine and cholera toxin in the growth medium when parameters were assayed in cell lysates. In contrast, when assays were performed using live cells, tyrosine hydroxylase demonstrated dramatic upregulation. Medium conditioned by CHS melanocytes demonstrated phenylthiourea-inhibitable tyrosinase activity. Melanocyte lysates and conditioned medium analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and DOPA staining showed an extra, approximately 100 kilodalton soluble protein band with DOPA positivity and tyrosinase immunoreactivity. In addition to tyrosinase, one of three lysosomal enzymes assayed (beta-glucuronidase) was aberrantly secreted into the medium. These results demonstrate that melanocytes cultured from CHS express a defect in the structure and/or function of the melanosome and abnormal trafficking of some cellular proteins. |
8041114 | Histopathology of regression in sinclair swine model of melanoma. | Detailed histopathologic studies of melanomas occurring in neonatal Sinclair miniature swine have demonstrated a remarkable similarity to human melanoma. A significant difference is the predictable, complete regression of primary and metastatic tumors that occurs in all animals by early adulthood (1 to 2 years). Prior histopathologic descriptions of regression in this model have been incomplete with regard to the time of onset and chronologic sequence of events. This lack of data makes it difficult to plan studies of regression mechanisms especially when requiring the harvesting of tumor tissue. By routine histologic methods, 94 tumors from 46 piglets were evaluated for the degree of regression, presence of pigment-laden macrophages, and presence of lymphocytes. One or more punch biopsies were performed on 51 tumors before excision, for a total of 256 biopsies. Regression took place in two phases. The first phase began during the 4th week after birth; was preceded by a rapid, massive infiltration of pigment-laden macrophages; and was most active during the 2nd month. Significant numbers of lymphocytes were rarely seen in tumors during this phase of regression. In the vast majority of tumors, this initial regression activity was followed by regrowth of residual tumor usually appearing as emerging clones (intralesional transformation). The second phase of regression was characterized by asymmetrically distributed lymphocytic infiltration of the residual melanoma, and progressive regression of tumor over several months. Significant numbers of lymphocytes were not present in the majority of the tumors until the beginning of the 4th month. We conclude that regression of melanoma in this animal model is a complex event in which the immune system participates differentially during the natural history of the disease. |
8041113 | Cytomegalovirus infection of human retinal tissue: an in vivo model. | Cytomegalovirus (CMV) retinitis is a common, devastating complication of AIDS. Strict host specificity of human CMV (HCMV), has limited the study of the virus. The purpose of this research was to create a model that allowed the in vivo infection of human retinal tissue with HCMV. Small fragments of 13-week human fetal retina were transplanted into the anterior chambers of immune-deficient mice. One week later, 15 of 30 grafts were inoculated with HCMV. Infected and noninfected specimens were compared for histopathologic changes at 14, 30, and 60 days at light and electron microscopic levels. Histochemistry was performed to characterize: level of graft differentiation, range of viral replication cycle, and effects on neuronal, glial, and monocytic elements of the retina. At 30 and 60 days, grafts were well differentiated histologically and histochemically. The infected grafts showed numerous large cells containing intranuclear and intracytoplasmic inclusions. Ultrastructural examination revealed viral particles within cytoplasm and nuclei. Infected cells expressed proteins representative of all phases of the HCMV replication cycle. Most HCMV-infected cells expressed the neuronal marker, protein gene product 9.5. In a second series of experiments, tissue from one graft harvested at 45 days postinfection was used to recover HCMV in fibroblast cultures and also used successfully to passage the virus to two control grafts. This model allows HCMV to actively infect and replicate within highly differentiated human neural tissue. It produces pathology characteristic of CMV-infected neural tissue in a time course suitable for long-term study. The nature of this model will allow the study of: the replication properties of HCMV in nervous tissue, the specific effects of HCMV on the human retina, the interaction of HCMV with other viruses, e.g., HIV, and various anti-viral therapies. |
8041112 | Structural alterations in heart valves during left ventricular pressure overload in the rat. | Heart valves are an important denominator of the function of the heart but detailed studies of structural alterations of heart valves after hemodynamic changes are lacking. Structural alterations of heart valves, including DNA synthesis, collagen mRNA, and protein concentration were measured in heart valves of Wistar Kyoto (WKY) rats with acute left ventricular pressure overload, created by intrarenal aortic ligation (AL, N = 18) as well as in heart valves of age-matched spontaneously hypertensive rats, a model of chronic hypertension (N = 18). SHAM aortic ligation and normal WKYs (N = 17 and N = 17) served as controls. All animals received 5'bromo-2' deoxyuridine, during the last 7 days of the experiment, in a dose of 2.4 mg/kg.day. The cumulative labeling fraction (LF) in the mitral valve of AL animals was 47.8 +/- 5.2% as compared with 9.4 +/- 2.6% in SHAM animals (mean +/- SEM, p < 0.01). The LF in the aortic valve of AL animals was 33.3 +/- 2.9% as compared with 7.7 +/- 0.7% in SHAM animals (p < 0.01). The LF in the tricuspid valve was also significantly increased: 11.3 +/- 1.4% in AL versus 5.8 +/- 0.7% in SHAM (p < 0.01). Labeling fractions of heart valves in SHR were not increased as compared with normal WKY. The total collagen concentration in the three heart valves, measured by the hydroxyproline assay, did not change. The mRNA amounts of both collagen type I and III, detected by in situ hybridization, were increased in the heart valves of AL and spontaneously hypertensive animals as compared with the two control groups (SHAM and WKY). In all 3 heart valves, interstitial cells were vimentin-positive, but desmin-negative. A fraction of interstitial cells showed alpha-smooth muscle actin positivity. This immunophenotype did not change during pressure overload. Heart valves have the capacity to adapt to acute pressure overload, by means of DNA synthesis and increased collagen turnover. The increase in LF in the normotensive tricuspid valve suggests a role for an additional circulating factor. A constant fraction of the interstitial heart valve cells consists of myofibroblasts. |
8041111 | Experimental murine pulmonary cryptococcosis. Differences in pulmonary inflammation and lymphocyte recruitment induced by two encapsulated strains of Cryptococcus neoformans. | Cryptococcus neoformans, the most common cause of lethal mycosis in AIDS, usually causes only subclinical pneumonitis in normal hosts. However, cryptococcosis can induce various pulmonary inflammatory reactions, and pulmonary cellular immunity is postulated to prevent dissemination. We hypothesized that cryptococcal strains possess different capacities to induce recruitment to the lungs of inflammatory cells, especially lymphocytes, which are necessary for cryptococcal clearance. We examined the pulmonary response of CBA/J mice to intratracheal inoculation with C. neoformans of either of two strains: 52D (ATCC 24067), which rarely kills immunocompetent mice; and 145A (ATCC 62070), which is uniformly fatal. From 2-42 days after inoculation, lungs were either examined grossly and microscopically or were enzymatically digested and inflammatory cells counted and analyzed by flow cytometry. At 42 days, organism burden in lung and brain was quantified by colony-forming unit assay. Pulmonary inflammation differed greatly between the two strains. Strain 52D induced dense perivascular and alveolar inflammation; infection progressed to day 21 and then waned. In contrast, strain 145A induced delayed, meager lymphocytic infiltration and slight alveolitis; organisms grew progressively. Recovery of inflammatory cells increased by day 13 with strain 52D, but not until day 31 with strain 145A. Although all lymphocyte subsets were greater in 52D infection, the disparity was greatest for CD4+ T cells. Nevertheless, lymphocytes from paratracheal nodes of infected mice proliferated in vitro to heat-killed cryptococci, indicating immune recognition of both strains. At day 42, strain 52D lightly infected lungs but not brain, whereas strain 145A heavily infected lungs and brain. CONCLUSIONS; Cryptococcal strains differ in their capacity to induce pulmonary cellular inflammation, especially CD4+ T cell recruitment. Our results suggest that strain-specific difference in the organism's ability to induce (or evade) pulmonary inflammation contributes to the outcome of infection. |
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