Search PubMed⌕ Search

Biomedical subjects

V Brown

Publications and source records attributed to V Brown.

At least 73 records · Page 4Linked to original sources
PubMed1995

The cellular isoform of the prion protein, PrPc, is associated with caveolae in mouse neuroblastoma (N2a) cells.

A major component of the infectious particle causing spongiform encephalopathies or prion diseases is an aberrant isoform (PrPSc) of a glycosyl-phosphatidylinositol (GPI)-anchored cell surface protein, PrPC. The cellular processes involved in the formation of PrPSc are unclear but involve the internalization of PrPC prior to conversion. Here, we demonstrate that PrPC is associated with caveolin, a structural protein component of caveolae. We show that PrPC and caveolin share similar detergent characteristics and copurify in linear sucrose gradients. PrPC was protected from proteinase K digestion in the caveolin fraction but solubilizing the caveolae prior to proteinase K digestion rendered PrPC susceptible to proteinase K digestion. Our results indicate a physical association between PrPC and caveolin in N2a cells. The implication of these results in relation to prion biogenesis is discussed.

Animals↗
PubMed1995

The influence of medium composition on the maintenance of cytochrome P-450, glutathione content and urea synthesis: a comparison of rat and sheep primary hepatocyte cultures.

Rat and sheep primary hepatocytes have been cultured in four different medium formulations: Williams' E, Chee's, Medium 199 and Modified Earle's. The total cytochrome P450 content, intracellular concentration of reduced glutathione, rate of urea synthesis and total protein content of cultures of cells from both species in each medium have been determined. Modified Earle's and Chee's medium proved to be the most favourable formulations for the culture of rat hepatocytes. After 48 h, cells cultured in Modified Earle's had significantly more cytochrome P450 and a significantly greater rate of urea synthesis than cells in any other medium. After 6 days in culture the difference in cytochrome P450 levels between rat hepatocytes in Chee's medium and those in Modified Earle's medium was abrogated. The difference in the rate of urea synthesis between rat hepatocytes cultured in each of these two media was shown to be more dependent on the medium in which the cells were maintained during the period of urea synthesis measurement than on the medium in which the cells had been previously cultured. Sheep hepatocytes cultured in Chee's medium ruptured and died within 24 h. Apart from this, sheep cells were less sensitive to changes in medium formulation than were rat hepatocytes. The initial plating efficiency was lower in sheep cells. Total cytochrome P450 content was the most discriminatory of the four parameters for evaluating the status of rat hepatocyte cultures. However, urea synthesis may be the most useful parameter for assessment of hepatocyte function in hybrid liver devices such as bioartificial liver support systems where access to the cells during operation of the device is restricted.

Ammonia↗
PubMed1995

The effects of poverty environments on elders' subjective well-being: a conceptual model.

This article presents a conceptual model, the Urban Ecological Model of Aging, to be used by researchers to assess the impact of living in neighborhoods of concentrated and prolonged poverty on elderly residential satisfaction and subjective well-being. Specifically, the suprapersonal environment characteristics, or aggregated people characteristics, of impoverished urban neighborhoods are explicated and included in a predictive model of community-dwelling elders' affective state, i.e., positive and negative affect. Demographic and personal characteristics are also included in the model as predictors.

Adaptation, Psychological↗
PubMed1994

Long-term treatment of hypercholesterolemia with dietary fiber.

PURPOSE: To evaluate the hypocholesterolemic effects of long-term treatment (36 to 51 weeks) with a mixture of dietary fibers (guar gum, pectin, soy, pea, corn bran) administered twice a day. PATIENTS AND METHODS: Fifty-nine subjects with moderate hypercholesterolemia who completed a 15-week, placebo-controlled study with the dietary fiber were treated for an additional 36 weeks with 20 g/day of fiber. Subjects were counseled and monitored on a National Cholesterol Education Program (NCEP) Step-One Diet before starting and during treatment. Analyses of changes in lipoprotein values during the additional 36 weeks of treatment took into account changes in weight, diet, and other variables that might have affected the response to treatment. RESULTS: There were no significant effects on the levels of either triglycerides or high-density lipoprotein cholesterol (HDL-C). Levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) and the LDL/HDL ratio were significantly reduced during treatment. The mean percentage reductions from baseline after 51 weeks of treatment were approximately 5% for TC, 9% for LDL-C, and 11% for the LDL/HDL ratio. Changes were apparent after 3 weeks of treatment, with the maximum reductions occurring by the 15th week of treatment. CONCLUSIONS: For subjects on a Step-One Diet who complied with the treatment regimen, the moderate cholesterol-lowering effects of the fiber persisted throughout the 36-to-51 week treatment period.

Chi-Square Distribution↗
PubMed1994

Cadmium toxicity to rainbow trout Oncorhynchus mykiss Walbaum and brown trout Salmo trutta L. over extended exposure periods.

The toxicity of cadmium in water is well known, but there have been few reports on the long-term effects of this metal on fish at concentrations near the European inland water standard of 5 micrograms Cd liter-1. This paper describes experiments in which adult rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta were exposed to cadmium concentrations near water quality standard levels for periods of up to 90 weeks. The survival and growth of these fish were assessed, and sperm and eggs were stripped from them to conduct early-life-stage tests. Continuous exposure of rainbow trout adults to cadmium concentrations of up to 5.5 micrograms Cd liter-1 did not affect their survival or growth. However, eggs obtained from rainbow trout exposed to 1.8 and 3.4 micrograms Cd liter-1 failed to develop to the fry stage. Oogenesis appeared to be delayed in brown trout exposed to 9.3 and 29.1 micrograms Cd liter-1, but the eggs and fry that were produced developed normally after fertilization. Adult brown trout suffered considerable mortality in the 29.1 micrograms Cd liter-1 treatment, with a median period of survival of 54 weeks.

Animals↗
PubMed1994

Hypocholesterolemic effects of a dietary fiber supplement.

The cholesterol-lowering effects of a fiber supplement were evaluated in patients with mild to moderate hypercholesterolemia. After a 9-wk diet stabilization period, patients were randomly assigned to treatment with 10 or 20 g/d of the fiber supplement or with a matching placebo. Among patients who completed the 15-wk treatment period, total cholesterol, LDL cholesterol, and the ratio of LDL to HDL (LDL/HDL) were significantly reduced (P < 0.05) for the 10- (n = 40) and 20-g/d (n = 39) groups compared with the placebo group (n = 48). In the placebo group and 10- and 20-g/d groups, the percent changes in total cholesterol were 0.4%, -5.8%, and -4.9%, in LDL cholesterol were -0.4%, -8.1%, and -7.3%, and in LDL/HDL were 1.0%, -5.6%, and -8.7%, respectively. The fiber supplement had no significant effects (P > 0.05) on HDL cholesterol or triglycerides. The changes in lipoprotein concentrations could not be attributed to changes in diet or body weight because there were no significant changes in these variables during the 15-wk treatment period.

Adolescent↗
PubMed1992

Prevalence of HIV-1 and HIV-2 mixed infections in Côte d'Ivoire.

We have investigated the cause of dual serological reactivity to human immunodeficiency virus (HIV) types 1 and 2, a common occurrence in West Africa. Serum specimens from 111 individuals from Côte d'Ivoire classified by commercial western blot as HIV-1 (n = 15), HIV-2 (32), and dually reactive (64) were further tested by more specific serological tests (a synthetic peptide enzyme immunoassay [Pepti-LAV 1/2] and western blots prepared from antigen in which oligomeric forms of the transmembrane protein were disrupted by trichloroacetic acid [WB-TCA]). Peripheral blood mononuclear cells were tested for HIV-1 and HIV-2 with the polymerase chain reaction (PCR) and virus culture. Of 104 samples that were concordant by both WB-TCA and Pepti-LAV, 82 (79%) were confirmed by PCR results. Virus culture was concordant with serology for specimens (35/38) in which any virus was detected. Our findings indicate that mixed HIV-1/HIV-2 infections are common in Côte d'Ivoire, and suggest that natural infection by one HIV type does not prevent heterologous infection.

Blotting, Western↗
PubMed1991

Reducing the effects of adjacent distractors by narrowing attention.

Three experiments explored the gradual narrowing of visual attention to a letter target when other letters were positioned close by. The method by which attention was narrowed involved presenting a digit target immediately prior to the latter target and in the same location for progressively shorter durations and requiring the subject to identify both the digit target and the letter target before responding. The response time data from the first 2 experiments indicated that shorter durations of the digit reduced the amount of information processed from noise letters positioned on either side of the letter target. In the third experiment, in which separation of letters was increased slightly, the response times indicated that the information from flanking noise letters may have been virtually eliminated.

Adult↗
PubMed1991

The family as victim in trauma.

In trauma, the intense immediate need for medical intervention and stabilization has focused attention on the victim's physical injuries, and away from the traumatic psychosocial impact on his life and family. Trauma teams are prepared to respond quickly and efficiently to sudden life and death situations, with the most up-to-date knowledge, technology and care. Until recently however, little organized, comprehensive attention has been given to the psychosocial responses of the patient and the family. It is now time to prepare ourselves to offer this other important aspect of trauma care--the psychosocial component. As a part of this preparation, I would like to present the Family as Victim in Trauma.

Family↗
PubMed1990

Poly(anhydride) administration in high doses in vivo: studies of biocompatibility and toxicology.

Poly(anhydrides) proposed for use as vehicles for controlled drug delivery were administered subcutaneously in Sprague-Dawley rats at two dosage levels (800 mg/kg rat and 2400 mg/kg rat) for a period of eight weeks. Biocompatibility was assessed using a number of methods. Thirty-six clinical chemistry and hematology parameters were monitored throughout the study. Blood values were statistically analyzed for any possible effects due to the implanted polymer. After 8 weeks, rats were sacrificed and complete necropsies were performed. Histological evaluations of 33 organ sites including heart, lung, liver, kidney, and brain were performed. In addition, subcutaneous implant sites were excised and examined both grossly and microscopically. Results from evaluations of blood chemistry and hematology data, organ analyses and local implant site analyses overall demonstrated that the poly(anhydride) biomaterial possessed excellent in vivo biocompatibility.

Animals↗
PubMed1990

Susceptibility of human neuroblastoma cell lines to cytotoxic T lymphocyte-mediated lysis.

The susceptibility of neuroblastoma cells to cytotoxic T lymphocyte (CTL)-mediated killing was investigated. Cytotoxic lines were generated by sensitizing peripheral blood lymphocytes against two stimulator cells, a neuroblastoma line, CHP-100, and normal allogeneic lymphocytes, LS. LS cells shared class I antigens with CHP-100, but in addition expressed class II antigens. The resulting cell lines strongly lysed both CHP-100 and LS cells, but poorly killed the natural killer (NK) target K562. Specific blocking of lysis by a monoclonal antibody directed against class I determinants and strong killing by the line following depletion of cells with NK or LAK markers demonstrated that this neuroblastoma line was lysed by CTL.

Antibodies, Monoclonal↗
PubMed1990

The independent effects of hyperandrogenaemia, hyperinsulinaemia, and obesity on lipid and lipoprotein profiles in women.

We performed this study to clarify the independent effects of hyperandrogenaemia, hyperinsulinaemia, and obesity on lipid and lipoprotein levels in women with hyperandrogenaemia (HA) and anovulation which we designated as the polycystic ovary syndrome (PCO). We examined fasting lipid, lipoprotein, sex hormone and insulin levels in 38 women (21 obese (ob), 17 non-obese (nob] with HA and anovulation (PCO) and 38 normal ovulatory women (21 obese, 17 non-obese), matched for age and weight. The women with PCO had significantly increased androgen levels compared to the normal women. However, total oestradiol levels were similar in the PCO and normal women. Mean fasting insulin levels and 2-h glucose levels (both P less than 0.001) were significantly higher in ob PCO women. There were significant decreases (P less than or equal to 0.01) in high-density lipoprotein (HDL) levels in both the obese groups (ob PCO and ob normal) compared to the non-obese (nob PCO and nob normal) groups. Otherwise, mean lipid and lipoprotein levels did not differ in the ob or the nob PCO women compared to the control groups. The correlations between sex hormone, lipid and lipoprotein levels differed in the four groups of women. After statistical adjustment for potential hormonal interactions, nob PCO women had significant positive correlations between testosterone and LDL levels (R = 0.51, P less than 0.05) and insulin and TTG levels (R = 0.61, P less than 0.01). Ob normal women had a significant positive correlation between oestrone and TTG levels (R = 0.44, P less than or equal to 0.05). We conclude that (1) PCO women are in a low to risk for CVD primarily because of the increased prevalence of obesity rather than the reproductive hormone abnormalities associated with this disorder. However, by their lipid profiles, the PCO women were still in a low to intermediate risk group for CVD.

Adolescent↗
PubMed1990

[The National Cholesterol Education Program].

Following a recommendation by the US Consensus Conference of December 1984, a National Cholesterol Education Program was initiated by about 30 different organizations. This program mainly addresses health professionals, such as physicians, nurses, dietitians etc. One of its objectives is to give physicians clear guidelines as to type and timing of interventions (diet, drugs). The program further comprises an extensive advertising campaign with the aim of reducing risk factors mainly by popularizing health-oriented nutrition.

Anticholesteremic Agents↗