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Biomedical subjects

R Wright

Publications and source records attributed to R Wright.

At least 91 records · Page 5Linked to original sources
PubMed1991

Health, stress, psychological resources, and subjective well-being among older blacks.

This study examines the structural relationships among sociodemographic characteristics, health status, stress, psychological resources, and subjective well-being (SWB) among the Black elderly. A structural equation model of SWB was evaluated with data from the 1979-1980 National Survey of Black Americans. The results revealed that poor subjective health status was predictive of lower levels of personal efficacy and SWB. Stressful life events tended to depress subjective assessments of health and had negative effects on self-esteem and SWB. Marital status and age had positive effects on SWB. Chronic health conditions and other demographic variables, however, had indirect effects on SWB.

Adaptation, Psychological↗
PubMed1991

Isolation and characterization of PEP3, a gene required for vacuolar biogenesis in Saccharomyces cerevisiae.

The Saccharomyces cerevisiae PEP3 gene was cloned from a wild-type genomic library by complementation of the carboxypeptidase Y deficiency in a pep3-12 strain. Subclone complementation results localized the PEP3 gene to a 3.8-kb DNA fragment. The DNA sequence of the fragment was determined; a 2,754-bp open reading frame predicts that the PEP3 gene product is a hydrophilic, 107-kDa protein that has no significant similarity to any known protein. The PEP3 predicted protein has a zinc finger (CX2CX13CX2C) near its C terminus that has spacing and slight sequence similarity to the adenovirus E1a zinc finger. A radiolabeled PEP3 DNA probe hybridized to an RNA transcript of 3.1 kb in extracts of log-phase and diauxic lag-phase cells. Cells bearing pep3 deletion/disruption alleles were viable, had decreased levels of protease A, protease B, and carboxypeptidase Y antigens, had decreased repressible alkaline phosphatase activity, and contained very few normal vacuolelike organelles by fluorescence microscopy and electron microscopy but had an abundance of extremely small vesicles that stained with carboxyfluorescein diacetate, were severely inhibited for growth at 37 degrees C, and were incapable of sporulating (as homozygotes). Fractionation of cells expressing a bifunctional PEP3::SUC2 fusion protein indicated that the PEP3 gene product is present at low abundance in both log-phase and stationary cells and is a vacuolar peripheral membrane protein. Sequence identity established that PEP3 and VPS18 (J. S. Robinson, T. R. Graham, and S. D. Emr, Mol. Cell. Biol. 11:5813-5824, 1991) are the same gene.

Adaptor Proteins, Vesicular Transport↗
PubMed1991

Deoxyribonucleic acid amplification and hybridisation in Crohn's disease using a chlamydial plasmid probe.

The possibility that Crohn's disease is caused by infection with Chlamydia trachomatis was examined by probing for chlamydial plasmid deoxyribonucleic acid (DNA) in DNA extracts from Crohn's disease tissue and by means of a serological study. Gut DNA extracts were obtained from 10 patients with Crohn's disease and four control subjects and were probed with a chlamydial plasmid probe after Southern blotting. The polymerase chain reaction was also used to amplify any chlamydial plasmid DNA present in tissue DNA extracts, before Southern blotting and probing. Chlamydial proctitis control specimens were not available: gut DNA extracts mixed with traces of chlamydia plasmid served as positive controls. Using these techniques, no chlamydial plasmid DNA sequences were found in Crohn's disease tissue. An enzyme linked immunosorbent assay for C trachomatis LI was performed on 48 patients with Crohn's disease and 48 control subjects. Seropositivity was present in 14.6% of patients and 29% of control subjects and was not statistically significant (p greater than 0.05). The failure to show chlamydial DNA and the lack of serological response to chlamydia make C trachomatis infection a very unlikely factor in the pathogenesis of Crohn's disease.

Adult↗
PubMed1990

Correlates of willingness to consider organ donation among blacks.

Professionals in the health care and organ procurement fields reveal that black Americans display limited commitment to organ donation. The present study represents an attempt to shed some light on this issue by examining the relationship of selected demographic, knowledge and attitude-belief variables to willingness to consider organ donation within a black population. Findings indicated that only a few of the demographic and knowledge variables were related to willingness to consider organ donation. All of the attitude-belief variables, however, were found to be significantly associated with the dependent variable. Implications of the findings for recruiting black organ donors and future research are discussed.

Adolescent↗
PubMed1990

Isolation and characterization of PEP5, a gene essential for vacuolar biogenesis in Saccharomyces cerevisiae.

pep5 mutants of Saccharomyces cerevisiae accumulate inactive precursors to the vacuolar hydrolases. The PEP5 gene was isolated from a genomic DNA library by complementation of the pep5-8 mutation. Deletion analysis localized the complementing activity to a 3.3-kb DNA fragment. DNA sequence analysis of the PEP5 gene revealed an open reading frame of 1029 codons with a calculated molecular mass for the encoded protein of 117,403 D. Deletion/disruption of the PEP5 gene did not kill the cells. The resulting strains grow very slowly at 37 degrees. The disruption mutant showed greatly decreased activities of all vacuolar hydrolases examined, including PrA, PrB, CpY, and the repressible alkaline phosphatase. Apparently normal precursors forms of the proteases accumulated in pep5 mutants, as did novel forms of PrB antigen. Antibodies raised to a fusion protein that contained almost half of the PEP5 open reading frame allowed detection by immunoblot of a protein of relative molecular mass 107 kD in extracts prepared from wild-type cells. Cell fractionation showed the PEP5 gene product is enriched in the vacuolar fraction and appears to be a peripheral vacuolar membrane protein.

Alkaline Phosphatase↗
PubMed1990

Viral hepatitis comparative epidemiology.

The epidemiology of HAV, HBV, HCV, HDV and HEV is compared. Spread of HAV and HEV is by the faecal/oral route whereas HBV, HCV and HDV are spread by blood or blood products. HEV is more likely to produce large epidemics than HAV but sporadic cases also occur. HBV, HCV and HDV all occur after blood transfusion, in haemophiliacs and intravenous drug abusers but they differ in their geographical distribution and in the frequency of perinatal transmission which is only common with HBV. Superinfection and interaction between these viruses is discussed.

Hepatitis A↗
PubMed1990

Microbial and endotoxin contamination in water and dialysate in the central United States.

The purified water supplies and randomly selected dialysates of 51 chronic and acute dialysis centers in the central United States were surveyed to assess the relative risks to dialysis patients from microbial and endotoxin contamination. A culture medium more sensitive than those generally employed in routine quality assurance assays was used for recovery of bacteria from water. With this medium, 35.3% of the water samples and 19% of the dialysate samples were out of compliance with the Association for the Advancement of Medical Instrumentation (AAMI) standards: 200 and 2,000 colony forming units (CFU)/ml, respectively. There was no correlation observed between the type of water purification system or the frequency of disinfection of the system and the bacterial and endotoxin contamination levels. There was also no correlation found between the bacterial and fungal CFU per ml and the endotoxin concentration per ml (EU/ml). It is recommended that more sensitive culturing methods be used to provide adequate bacterial monitoring of dialysate center water supplies. Dialysis centers should monitor endotoxin in dialysate on a regular schedule and immediately after any endotoxemic-like patient reactions. Yeast and fungi were observed in 10% and 64% of the water systems, respectively. Dialysate was contaminated by yeast and fungi in 30% and 70% of the centers, respectively. The concentrations of these microbes in both fluids were much lower than bacteria. However, they were observed often enough to warrant further investigation of their impact on the well-being of dialysis patients.

Bacteria↗
PubMed1990

Bleeding oesophageal varices associated with anabolic steroid use in an athlete.

A 30 year old bodybuilder who had been taking anabolic steroids for 18 months presented with bleeding oesophageal varices. Serious liver disease secondary to anabolic steroids including peliosis hepatis, nodular hyperplasia and malignant change is well recognized. We report what is, to our knowledge, the first case of bleeding oesophageal varices associated with the use of anabolic steroids.

Adult↗
PubMed1990

Cell-type control of membrane biogenesis induced by HMG-CoA reductase.

Quantitative increases in HMG-CoA reductase, the rate-limiting enzyme in sterol biosynthesis, induce membrane biogenesis in both yeast and mammalian cells. The subcellular organization of the resulting membrane differs in the two cell types: mammalian cells generate crystalloid endoplasmic reticulum whereas yeast cells assemble karmellae. We examined the consequences of heterologous expression of HMG-CoA reductase to distinguish features of this response that were cell-type specific from those that were isozyme-specific. This analysis demonstrated that membrane proliferation was induced in both mammalian and yeast cells by HMG-CoA reductase from either organism. However, the morphology of the induced membranes was determined by the cell type rather than the particular isozyme. Thus, both yeast and mammalian HMG-CoA reductase contained functional signals for membrane proliferation that were operational in either cell type, but the qualitative response to those signals was cell-type specific.

Animals↗
PubMed1990

Endotoxin and bacterial contamination of dialysis center water and dialysate; a cross sectional survey.

The bacterial and endotoxin levels of purified water and effluent dialysate were examined in a cross section of dialysis centers in the central United States. All samples were collected within a four-hour drive of the University of Louisville and were collected, processed and analyzed by our personnel, to eliminate variability in sample handling. A medium capable of higher bacteria recovery from aqueous environments than those ordinarily employed in clinical assays was used. Endotoxins were determined by a quantitative colorimetric assay. By the more sensitive bacterial assay 53% of the centers had bacterial counts above the AAMI standard of 200 colony-forming units per ml (CFU/ml) for water and 35% of the centers had bacterial counts above the 2000 CFU/ml standard for dialysate in at least one sampling period. The samples showed 35% and 19% of water and dialysate above the standards, respectively. While there are no standards for endotoxin concentrations in water used to prepare dialysate, 2% of the centers had endotoxin levels in their water above five endotoxin units per ml (5 EU/ml = 1 ng/ml in our assay kit), the limit set by the AAMI standards for reprocessor water. Both bacterial and endotoxin levels tended to be elevated in dialysate, with the highest levels of endotoxin in dialysates posing an obvious potential risk when high-flux dialyzers are used.

Bacteria↗
PubMed1989

The flow/volume curve as a mass screening test with emphasis on quality control.

Air flow through the airways is influenced by different mechanical characteristics of the respiratory system and can be affected by pathological changes in the lungs. Lung volume is probably the most important independent variable determining air flow through the airways. Therefore, it is logical that lung volume should form the ordinate of a curve used to demonstrate the variation of airflow through the airways during forced inspiratory and expiratory manoeuvres. The flow/volume curve is in many ways superior to other measurements of lung function for clinical and epidemiological assessments. Most of the problems that have to be overcome in obtaining satisfactory and repeatable flow/volume curves are discussed and illustrated. A computer system which optimises quality control is described. By making use of this system, operator error can be reduced to a minimum. It is recommended that hard copies of the three efforts must be available and that all flow/volume measurements be controlled by a knowledgeable person before the results are entered in the records.

Adult↗
PubMed1989

A comparison of oral milrinone, digoxin, and their combination in the treatment of patients with chronic heart failure.

We randomly assigned 230 patients in sinus rhythm with moderately severe heart failure to treatment with digoxin, milrinone, both, or placebo. The effects of each were compared during a 12-week, double-blind trial. Treatment with milrinone or digoxin significantly increased treadmill exercise time as compared with placebo (by 82 and 64 seconds respectively; 95 percent confidence limits, 44 and 123, and 30 and 100). Both treatments reduced the frequency of decompensation from heart failure, from 47 percent with placebo to 34 percent with milrinone (P less than 0.05; 95 percent confidence limits, 22 and 46) and 15 percent with digoxin (P less than 0.01; 95 percent confidence limits, 7 and 26). However, the clinical condition of 20 percent of the patients taking milrinone deteriorated within two weeks after treatment was begun, as compared with only 3 percent of those taking digoxin (P less than 0.05). The left ventricular ejection fraction at rest was not significantly changed by milrinone (+0.2 percent; 95 percent confidence limits, -1.5 and 1.9), but it was increased by digoxin (+1.7 percent; P less than 0.01; 95 percent confidence limits, -0.03 and 3.4) and decreased by placebo (-2.0 percent; 95 percent confidence limits, -3.8 and -0.1). Three-month survival was related inversely to the base-line ejection fraction. Analysis of mortality from all causes according to the intention to treat suggested an adverse effect of milrinone (P = 0.064). After adjustment for an excess of patients with lower ejection fractions randomly assigned to receive milrinone, this trend was not significant (P = 0.26). Increased ventricular arrhythmias occurred more frequently in patients who received milrinone than in those who did not (18 vs. 4 percent; P less than 0.03). We conclude that milrinone significantly increased exercise tolerance and reduced the frequency of worsened heart failure. However, in the population of patients studied, milrinone or the combination of milrinone and digoxin offered no advantage over digoxin alone. Furthermore, our data suggest that milrinone may aggravate ventricular arrhythmias.

Administration, Oral↗
PubMed1989

Analysis of the wheal-and-flare reactions that follow the intradermal injection of histamine and morphine in adults with recurrent, unexplained anaphylaxis and systemic mastocytosis.

It has been suggested that patients with recurrent, unexplained anaphylaxis may be more responsive, and patients with systemic mastocytosis, less responsive, to mast cell-derived mediators, including histamine, compared to normal subjects. This would help explain why patients with recurrent, unexplained anaphylaxis have an anaphylactic response and, conversely, why patients with systemic mastocytosis can tolerate high levels of plasma histamine. To test this hypothesis, intradermal titrations (0.02 ml of solution from 1 ng/ml to 2 micrograms/ml) of histamine and morphine sulfate (MS) (10 ng/ml to 10 micrograms/ml) were administered to normal volunteers (N = 15), patients with recurrent, unexplained anaphylaxis (N = 10), and patients with systemic mastocytosis (N = 18). Antihistamines were stopped at least 72 hours before the study. Resultant areas of wheal and flare were determined with a computerized morphometric system. Comparison of any two given means at each dose of histamine or morphine with the two-sample Student's t test with Bonferroni inequality demonstrated no significant differences (p greater than 0.05) among the three groups. The median amount of MS or histamine required to produce a half-maximal response was compared for equality. None of the differences observed reached statistical significance, in agreement with the similarity of the dose-response curves. An analysis of the correlation between response to MS and to histamine in individual subjects revealed the responses to be significantly correlated in all cases, with the exception of wheal in patients with recurrent, unexplained anaphylaxis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Transmission electron microscopy and immunocytochemical studies of yeast: analysis of HMG-CoA reductase overproduction by electron microscopy.

The results and anecdotes presented here are intended only as a general guide to other would-be immunocytochemists, because other proteins will undoubtedly respond at least somewhat differently than does HMG-CoA reductase. Nevertheless, based on these experiences, we offer the following suggestions: 1. Antiserum of high specificity should be raised and affinity-purified. Using this antiserum, immunofluorescence microscopy should be attempted before resorting to electron microscopic localization. In the absence of immunolocalization at the light-microscope level, it may be a waste of time to pursue the problem to higher levels of resolution. 2. Cells should be prefixed in 1% formaldehyde-1% glutaraldehyde. Direct fixation of the growing culture and use of phosphate buffer are recommended. The prefixed sample can then be divided into two or three aliquots. One aliquot should receive no postfixation (for optimal immunoreactivity), while the others can be postfixed in osmium-potassium ferricyanide (for possible immunolocalization) or permanganate (for ultrastructural analysis). Because of its ease of use, Spurr's resin should be tried initially. If immunocytochemistry is successful, no further preparations are necessary. If unsuccessful, LR White resin is recommended, but the sample must be treated to remove the cell wall. Electron microscopy and immunocytochemistry offer views into the molecular arrangement of individual cells, a view not easily obtained by other means. It is satisfying and often enlightening to be able to see the extremes as well as the average. In studies of the organization of karmellae, for example, ultrastructural analysis easily revealed the asymmetric segregation pattern, while immunoblots and cell fractionation could not even demonstrate the existence of this membrane organization. The richness of the information available to those who can avert reductionist tendencies, even for a short time, is remarkable.

Histocytochemistry↗
PubMed1989

Bacterial contamination of hemodialysis center water and dialysate: are current assays adequate?

Many dialysis centers depend on clinical laboratories or a commercially available dip culture to determine the contamination levels in water and dialysate. To determine whether these standard clinical culture procedures adequately quantitate bacterial contamination in hemodialysis center water and dialysate, test results of two routine clinical media was compared, trypticase soy agar (TSA) and plate count agar (PCA), with those of nutrient-poor R2A medium. Dialysate samples demonstrated significant differences in media, the temperature of incubation, and plating techniques (pour plate versus spread plates). Purified water for dialysis demonstrated significant differences only for media; however, temperature was an important variable. Selective growth on R2A agar of some water- and dialysate-contaminating species was studied by velvet disk and loop transfer of colonies. A strong selectivity for water-borne bacteria was demonstrated by R2A agar; the bacteria that did not grow on TSA and PCA have been identified.

Bacteriological Techniques↗