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Biomedical subjects

J Cohen

Publications and source records attributed to J Cohen.

At least 937 records · Page 52Linked to original sources
PubMed1992

Expedition stress and personality change.

There have been few attempts to investigate the widespread assumption that short-term challenges can have beneficial effects on personality. An expedition to India organized by the British Schools Exploring Society provided such an opportunity. The Gordon Personal Profile Inventory showed that the expedition was associated with increased ascendancy, emotional stability, sociability and responsibility, and decreased cautiousness. Women tended to benefit more than men. The results suggest that the expedition was associated with positive personality changes, though other explanations of the findings cannot be ruled out.

Adolescent↗
PubMed1992

Differential effects of monoclonal antibodies to tumor necrosis factor alpha and gamma interferon on induction of hepatic nitric oxide synthase in experimental gram-negative sepsis.

To investigate the stimuli required for the induction of nitric oxide synthase (NOS) in sepsis, we have analyzed the levels of this enzyme in the livers of mice infected with a 90% lethal dose of Escherichia coli in a model of gram-negative sepsis. Hepatic NOS levels are markedly induced in this model, with peak values occurring 12 to 22 h following infection. Treatment with TN3-19.12, a neutralizing monoclonal antibody to tumor necrosis factor alpha (TNF-alpha), resulted in complete protection from death in this model of sepsis but had no significant effect on the level of induction of hepatic NOS. Treatment with H22, a monoclonal antibody to gamma interferon (IFN-gamma), also gave significant protection against death and, in addition, did lead to a decrease in the level of induction of the hepatic NOS. Treatment of mice with pure TNF-alpha (0.2 microgram), IFN-gamma (2,000 U), or a combination of the two did not induce the hepatic NOS, but treatment with the combination led to significant mortality (probability of survival at 22 h, 0.32). Thus, the level of induction of NOS within the liver either in sepsis or by the coadministration of TNF-alpha and IFN-gamma does not correlate with death.

Amino Acid Oxidoreductases↗
PubMed1992

Use of randomly amplified polymorphic DNA markers to distinguish isolates of Aspergillus fumigatus.

Forty-four oligonucleotide decamers were tested for their abilities to generate randomly amplified polymorphic DNA (RAPD) markers from genomic DNAs of three different isolates of Aspergillus fumigatus. Seven primers generated RAPDs that allowed the three isolates to be differentiated; one of the primers also yielded a unique RAPD pattern in each of an additional six fungal isolates, demonstrating the utility of this technique for distinguishing between A. fumigatus isolates.

Aspergillosis↗
PubMed1992

Expression of the major capsid protein VP6 of group C rotavirus and synthesis of chimeric single-shelled particles by using recombinant baculoviruses.

VP6 of group C (Cowden strain) rotavirus was expressed in the baculovirus system. The recombinant protein, expressed to a high level in insect cells, was purified by ion-exchange chromatography. The purified protein was proven to be trimeric. The effect of pH on the trimer's stability was investigated. Coexpression of VP6 from group A (bovine strain RF) and VP6 from group C in the baculovirus system did not result in the formation of chimeric trimers. Coexpression of VP2 from group A rotavirus (bovine strain RF) and VP6 from group C in the baculovirus system led to the formation of chimeric, empty, single-shelled particles. These results demonstrate conservation in the domains necessary for binding to VP2 in different serogroups of VP6. The locations of the domains involved in trimerization and in the interaction with VP2 are discussed.

Animals↗
PubMed1992

Interaction of rotavirus particles with liposomes.

We have studied the interactions of purified viral particles with liposomes as a model to understand the mechanism of entry of rotavirus into the cell. Liposomes, made from pure as well as mixed lipids, that contained encapsulated self-quenching concentrations of the fluorophore carboxyfluorescein (CF) were used. Rotavirus-liposome interactions were studied from the fluorescence dequenching of CF resulting from its release to the bulk solution. Purified infectious double-shelled virus particles induced a concentration- and temperature-dependent release of CF. The rate and extent of CF release was maximum between pH 7.3 and 7.6. The removal of outer structural proteins VP4 and VP7 from virus, which results in the formation of single-shelled particles, prevented virus interaction with liposomes. Rotavirus particles with uncleaved VP4 did not interact with liposomes, but treatment in situ of these particles with trypsin restored the interaction with the liposomes and resulted in CF dequenching. Our data support the view that rotavirus enters the cell through direct penetration of the plasma membrane. In contrast, adenovirus, the only other nonenveloped virus studied by this method, shows the optimum rate of marker release from liposomes at around pH 6 (R. Blumenthal, P. S. Seth, M. C. Willingham, and I. Pastan, Biochemistry 25:2231-2237, 1986). The interaction between rotavirus and liposomes is sensitive to specific divalent metal ions, unlike the adenovirus-liposome interaction, which is independent of them.

Animals↗
PubMed1992

Endotoxaemia and serum tumour necrosis factor as prognostic markers in severe acute pancreatitis.

Endotoxaemia and circulating tumour necrosis factor are important prognostic factors in severe sepsis and are implicated in the pathogenesis of septic shock. Because clinical and pathological features in acute pancreatitis are similar to septic shock this study sought to determine whether endotoxin and tumour necrosis factor were prognostic factors in 38 patients with prognostically severe acute pancreatitis. Endotoxaemia, present in 19/37 (51%) patients on day 1, was more common in nonsurvivors than survivors (10/11, 91% v 9/26, 35%, p = 0.003). Day 1 serum endotoxin concentrations were higher in patients with a severe outcome (median (interquartile range) 314 (173-563) pg/ml v 0 (0-185) pg/ml, p<0.01) and in non-survivors (266 (173-586) pg/ml v 0 (0-165) pg/ml, p<0.01). Serum tumour necrosis factor was detectable in 47 of 109 samples (43%) from 38 patients (median 35 pg/ml, range 5-943 pg/ml). Day 1 serum tumour necrosis factor correlated with a worse prognostic score and a severe outcome in all patients (n = 38, r = 0.36, p = 0.027; r = 0.33, p<0.05) and with mortality in patients with gall stones (n = 23, r = 0.50, p = 0.02). Our data suggest that endotoxin and tumour necrosis factor could be prognostic factors in severe acute pancreatitis.

Acute Disease↗
PubMed1992

Discovery of a well-absorbed, efficacious renin inhibitor, A-74273.

The development of orally active renin inhibitors has been plagued by limited bioavailability in animals and humans. A-74273 is a novel, potent nonpeptide inhibitor of human renin (IC50 = 3.1 nM). This compound was absorbed into the portal and systemic circulations of anesthetized rats, ferrets, monkeys, and dogs after intraduodenal dosing. This favorable pattern also was observed after oral dosing in conscious animals, except in monkeys. Hepatic extraction of A-74273 was more efficient in rats and monkeys than in dogs or ferrets. A-74273 modestly inhibits dog renin, and when given orally as the base (0, 0.3, 1, 3, 10, and 30 mg/kg; n = 8 per dose) to conscious, salt-depleted dogs it induced dose-related reductions in mean arterial pressure and plasma renin activity. Peak falls in mean arterial pressure from normotensive baselines were -14 +/- 1, -26 +/- 3, and -44 +/- 3 mm Hg for the 3, 10, and 30 mg/kg groups, respectively (p < 0.05). Baseline plasma renin activity values (10.9 +/- 1.1-12.7 +/- 1.1 ng angiotensin I/ml/hr) were maximally inhibited, ranging from 43 +/- 8% at 0.3 mg/kg to 98 +/- 1% at 30 mg/kg. Bioavailability in this model was estimated to be 54 +/- 13% when plasma drug levels were determined by a renin inhibitory activity assay, but bioavailability was lower when compared with high-performance liquid chromatographic analysis of A-74273. This discrepancy was accounted for by the identification of structurally similar metabolites that are as active as the parent drug against human renin but much less potent against dog renin.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1992

Distribution of two common idiotypes of anticardiolipin antibodies in sera of patients with primary antiphospholipid syndrome, systemic lupus erythematosus and monoclonal gammopathies.

The frequency of two common idiotypes of anticardiolipin antibodies (aCL) was determined in sera from three groups of subjects, patients with systemic lupus erythematosus (SLE), with primary antiphospholipid syndrome (PAPS) and with monoclonal gammopathies (MG), as compared to normal population. The idiotype 1.10, which was derived from a patient with active SLE and antiphospholipid syndrome, was found more frequently among patients with PAPS (10.5%, 10.5% and 22.2% in MG, SLE and PAPS, respectively) than the idiotype H3, which was derived from a human hybridoma monoclonal aCL generated from a healthy subject immunized with tetanus and diphtheria. The latter idiotype was detected in 8.7%, 6.5% and 11.7% of patients with MG, SLE and PAPS, respectively. Incidental findings in this study include a high prevalence of aCL among patients with MG (23%) and a high prevalence of anti-dsDNA antibodies, detected only by a sensitive enzyme-linked immunosorbent assay, among patients with PAPS. Our results indicate that idiotypic diversity exists among aCL derived from different sources. Some of these cross-reactive idiotypes may be more pathogenic than others.

Adult↗
PubMed1992

Change in locus of control following admission in adolescent in-patients.

A multidimensional measure of children's perception of control was administered to 56 adolescents before and after admission. Different sources of control ('internal', 'powerful others' and 'unknown') were analysed by domain (sphere of behaviour) and outcome ('success' or 'failure'). There were changes across domain and outcome for all three sources of control with significant changes away from 'powerful others' and 'unknown' control. The trend towards internality was also evident in significant changes in the adolescents' perceptions in the 'general' domain and for a 'success' outcome. Changes towards 'internal' source of control were associated with higher cognitive ability, whereas changes away from 'powerful others' were most marked in girls, and changes away from 'unknown' were greatest in the older adolescents. These preliminary observations may help us understand beneficial effects of in-patient care and plan strategies for sustained change in these patients.

Adolescent↗
PubMed1992

Access to medical care for HIV-infected individuals under the Americans with Disabilities Act: a duty to treat.

In 1990, Congress enacted the Americans with Disabilities Act (ADA). This Note examines the legislative history of the ADA and uncovers Congress's intent to impose a duty on health care providers to treat people with disabilities unless an individual poses a "direct threat" to the health or safety of others. This Note posits that, with the passage of the ADA, Congress imposed a statutory duty on health care providers to give care to people infected with HIV who qualify under the statute. This Note concludes that while the "direct threat" exception may lessen the impact of the ADA, those infected with HIV should enjoy greater access to health care than ever before.

Persons with Disabilities↗
PubMed1992

Kidney allocation under the UNOS point system: an update.

1. The 1,480 patients awaiting cadaveric renal transplants at 14 Southern California transplant centers as of December 3, 1992, were compared with patients transplanted using a point system for one kidney and a hospital-based allocation for the second, or the current system allocating all locally procured kidneys by the point system with regard to several demographic parameters. 2. Of 1,472 waiting patients with sensitization data, 8.5% were broadly sensitized (> 80% PRA). Of the 737 kidneys allocated by the point system, 7% went to broadly sensitized patients, compared with 3% of 438 kidneys allocated by the hospitals (p < 0.001). 3. Of 1,470 waiting patients with information available, 23% were awaiting a repeat transplant. Under the point system, 18% of kidneys were used for repeat transplants compared with 9% of hospital-allocated kidneys (p < 0.001). 4. Of 1,434 waiting patients where the time waiting was available, 26% had waited 1-2 years, 12% 2-3 years, and 6% more than 3 years. Under the point system, patients waiting longer received significantly more kidneys than those recently added to the list: 35% had waited 1-2 years, 21% 2-3 years and 14% more than 3 years (p < 0.001). Kidneys allocated by the hospitals were transplanted to patients in approximately the same proportions as the waiting list: 29% to those waiting 1-2 years, 10% 2-3 years, and 3% more than 3 years. 5. Racial distribution of recipients was not significantly different under either allocation system from that of the waiting list. Whites comprised 39% of waiting patients, the same as the population of Los Angeles County.(ABSTRACT TRUNCATED AT 250 WORDS)

California↗
PubMed1992

Selective assisted hatching of human embryos.

Overall results of assisted hatching by zona drilling using acidic Tyrode's solution performed during three randomised trials in 330 in vitro fertilisation (IVF) patients are presented. It was demonstrated retrospectively and prospectively that assisted hatching by zona drilling was effective in embryos with thick zonae (> 15 microns). This procedure is called selective assisted hatching. In order to investigate whether the success rate of embryos with thin zonae (< 13 microns) can be improved further, a fourth trial was executed in 40 consenting patients. Embryos with thin zonae were left intact in one group (control), while the outside of zonae of similar embryos were thinned with acidic Tyrode's solution. Results thus far indicate that embryos with thin zonae do not benefit from this technique. Embryonic implantation (fetal heartbeat per embryo) was high (26%-27%) in both arms of the trial, probably as a result of selective zona drilling of low prognosis embryos with thick zonae. A method is presented for quantifying zona hardening in human embryos. The exposure to acidic Tyrode's solution of each embryo was expressed as a function of the duration to pierce the zona and the diameter of the needle. Preliminary findings suggested that embryonic viability is correlated with zona hardening. In order to test the hypothesis that extracellular fragments may affect embryonic viability, small amounts of fragments were removed from embryos during assisted hatching. The pregnancy rate in 36 patients with extracted fragments was relatively high (41%) considering the poor morphology of the embryos involved.

Adult↗
PubMed1992

Dual infection with Pneumocystis carinii and respiratory viruses complicating bone marrow transplantation.

Pneumonia due to dual infection with Pneumocystis carinii and respiratory viruses is a rare but formidable complication of bone marrow transplantation. We report here two cases of viral infections complicating P. carinii pneumonia in bone marrow transplant recipients who, at the time of infection, were not taking P. carinii prophylaxis. Both patients died following the pneumonia. Potential factors contributing to the dual infection included graft-versus-host disease, high-dose steroids and cyclosporin A. P. carinii prophylaxis should be continued for 12 months, or longer in bone marrow transplant recipients requiring prolonged immunosuppressive therapy. As specific antiviral therapy becomes available for some respiratory viral infections, performing regular viral surveillance cultures and responding with active early treatment may help improve the outcome in these immunocompromised patients.

Adenovirus Infections, Human↗
PubMed1992

Effects of angiotensinase inhibitors on plasma protein binding and IC50 determinations of renin inhibitors.

To establish whether the use of proteinase inhibitors in the routine determination of in vitro plasma renin activity overestimates the potency of renin inhibitors in vivo, we examined the effects of phenylmethylsulfonyl fluoride and 8-hydroxyquinoline sulfate on the binding to plasma proteins and the respective IC50 values (50% inhibiting concentrations) of three renin inhibitors. All three renin inhibitors, A-64662, A-65317, and A-74273, bound (> 60%) to plasma proteins at both pH 6.0 and 7.4, with slightly greater binding at pH 7.4. Phenylmethylsulfonyl fluoride (1.45 mmol/L) had no significant effect on the protein binding at either pH 6.0 or 7.4; 8-hydroxyquinoline sulfate (3.4 mmol/L) caused a modest dissociation (10-30%) of the renin inhibitors from plasma proteins at both pH values; and the effects of both proteinase inhibitors together were similar to those of 8-hydroxyquinoline alone. At pH 7.4, phenylmethylsulfonyl fluoride increased the potencies of the three renin inhibitors slightly (< or = 43%), whereas IC50 values determined in the presence of 8-hydroxyquinoline decreased by 1.5- to 3.7-fold. The greatest increase in potency occurred with the most hydrophilic compound, and with both angiotensinase inhibitors the effect was no greater than that of 8-hydroxyquinoline alone. The results show that any dissociation of the hypotensive activity measured in vivo from the plasma renin activity measured in vitro is not simply an artifact in the plasma renin activity assay stemming from the use of these angiotensinase inhibitors, especially if only phenylmethylsulfonyl fluoride is used.

Amides↗
PubMed1992

Shelf life of drugs.

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Drug Information Services↗