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Biomedical subjects

M Warner

Publications and source records attributed to M Warner.

At least 199 records · Page 11Linked to original sources
PubMed1987

Isolation and catalytic activity of cytochrome P-450 from ventral prostate of control rats.

5 alpha-Androstane-3 beta, 17 beta-diol hydroxylase (3 beta-diol hydroxylase), a form of cytochrome P-450, was purified from rat ventral prostate, and its regulation as a function of age and 5 alpha-dihydrotestosterone (DHT) treatment was examined. Cytochrome P-450 could be quantitated by its CO difference spectrum only after partial purification from the microsomal membrane, and this was achieved by chromatography on p-chloroamphetamine-coupled Sepharose. Further purification of prostate microsomal P-450 by anion exchange chromatography yielded a preparation with a P-450 content of 8-10 nmol/mg of protein, which upon sodium dodecyl sulfate electrophoresis showed, in the molecular weight region between 50,000 and 60,000 where P-450 is expected to migrate, a single protein band of Mr 54,000. This preparation upon reconstitution with cytochrome P-450 reductase and microsomal lipid catalyzed the formation of three triols, 5 alpha-androstane-3 beta, 7 beta, 17 beta-triol, 5 alpha-androstane-3 beta, 6 alpha, 17 beta-triol, and 5 alpha-androstane-3 beta, 7 alpha, 17 beta-triol from 3 beta-diol in the ratio 1:7:3. Both turnover number and the ratio of the three products in the reconstituted system were similar to that found in prostate microsomes. These data indicate that a single form of P-450 catalyzes the formation of all three triols and that 3 beta-diol hydroxylase is the major, if not the only, form of P-450 in the prostate microsomes of untreated rats. The yield of P-450 from prostate microsomes varied as a function of age from a high level of 0.05 nmol/mg of microsomal protein in 6-week-old rats to 0.002 nmol/mg of microsomal protein in rats 11 weeks or older. 3 beta-Diol hydroxylase activity followed a similar age-related pattern varying between 2,000 and 4,000 nmol of triols formed/g of tissue/h in 6-week-old rats to 100 nmol of triols formed/g of tissue/h in 11-week-old rats. Treatment of 6-week-old rats with DHT did not prevent the age-related decrease in 3 beta-diol hydroxylase activity. However, DHT does play a role in the regulation of this enzyme since castration resulted in a loss of catalytic activity from the prostate and treatment of castrated rats with DHT caused an induction of the enzyme.

Age Factors↗
PubMed1986

Production of extracellular enzymes and cytotoxicity by Vibrio vulnificus.

Thirty-three strains of Vibrio vulnificus of clinical and environmental origin were examined for production of 12 extracellular enzymes of potential importance to the virulence of this bacterium. Strains of Vibrio vulnificus were consistent in their production of protease, mucinase, lipase, chondroitinase, hyaluronidase, DNase, sulfatase, and hemolysin. No differences between clinical and environmental isolates were noted. Although none of the enzymes appeared to correlate with the ability of these strains to produce lethality in mice, the production of hemolysin and of a protease with activity against native serum albumin may be significant in the pathogenesis of the potentially fatal infections produced by this organism. The production of several of these exoenzymes also appeared to correlate with pathogenicity in the seven other Vibrio species examined. Culture filtrates of all virulent strains of Vibrio vulnificus were cytotoxic for Chinese hamster ovary cells, whereas those of the strains of Vibrio parahaemolyticus and Vibrio alginolyticus examined lacked this activity.

Animals↗
PubMed1986

A physical map of the viral genome for infectious pancreatic necrosis virus Sp: analysis of cell-free translation products derived from viral cDNA clones.

The two segments of double-stranded RNA from infectious pancreatic necrosis virus Sp were cloned into the plasmid vector pUC8. Two sets of overlapping clones were identified by restriction enzyme and Southern blot analyses. Each of these sets was shown by Northern blot analysis to be exclusively related to either segment A or B of the genomic RNA. The entire lengths of the cloned segments were estimated to be 2.9 and 2.6 kilobases, respectively. Sequences from the two segments of viral cDNA were subcloned into the bacteriophage T7 RNA polymerase vectors pT71 and pT72. The activity of the single-stranded RNAs transcribed from these subclones in a rabbit reticulocyte lysate translation system provided information on the polarity of and the protein products coded for by each subclone. The four proteins encoded by the genome of infectious pancreatic necrosis virus were identified among the translation products of the individual cloned segments by immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. By constructing plasmids containing deletions in the sequences from either the 5' or 3' end of segment A, we were able to construct a physical map for the larger segment of double-stranded RNA. The proteins derived from these plasmids indicated that the linear gene order for viral proteins encoded in segment A is beta, gamma 2, and gamma 1.

Animals↗
PubMed1985

Self-management of nutrition.

Eleven overweight subjects received a behavioral treatment program for weight loss and a nutritional self-management program during a 10-week treatment period. The nutritional self-management program was evaluated using a multiple-baseline across-groups design. The results indicated that caloric restriction without the nutritional self-management program did not result in the consumption of a well-balanced diet. Introduction of the nutritional self-management program led to improvement of nutritional consumption across six food groups. Self-control of caloric intake within certain food groups, i.e., fruit and vegetable, was better than for others. These findings are discussed in terms of the methodological difficulties involved in managing nutrition and the significance of nutritional self-management for health problems other than obesity.

Behavior Therapy↗
PubMed1985

Regulation of renal vitamin D hydroxylase activity in vitamin D deficient rats.

The regulation of renal mitochondrial 1-hydroxylase activity in chronic vitamin D deficiency was studied in male rats. These rats were born of mothers who had been raised from weaning (21 days) on a vitamin D deficient diet and who had no detectable serum 1,25-dihydroxycholecalciferol (1,25-(OH)2D) at the time their offspring were weaned (28 days). In the pups, renal mitochondrial 1-hydroxylase activity was undetectable before the 3rd week of life even though the animals were severely hypocalcemic from birth. The 1-hydroxylase activity first became detectable at 26 days of age, rapidly reached a maximum at day 34, then decreased to become undetectable again by 65 days. Throughout this time serum calcium concentration was less than 5.0 mg/dL and serum parathyroid hormone (PTH) concentration, measured by a midmolecule radioimmunoassay, was two- to five-fold greater than that found in vitamin D replete rats. 1-Hydroxylase activity could be restored in the +65-day-old animals by administration of a single dose of 2.5 micrograms vitamin D3. Enzyme activity was detected within 24 h, was maximal at 72 h, and returned to undetectable levels by 96 h after administration of the vitamin. Serum 1,25-(OH)2D which was undetectable before administration of the vitamin D3, was 108 and 458 pg/mL at 16 and 40 h, respectively, after the injection. The serum concentration of this metabolite then decreased progressively to 80 pg/mL by 6 days. 24-Hydroxylase activity first became detectable 48 h after vitamin D administration, increased to a maximum at 96 h, and thereafter decreased to become undetectable by 7 days.(ABSTRACT TRUNCATED AT 250 WORDS)

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed1984

Automated detection of micro-organisms in blood cultures by means of the Malthus Microbiological Growth Analyser.

A prototype Malthus Microbiological Growth Analyser was compared with conventional methods for examining blood cultures in a trial of 651 cultures mostly from patients with haematological malignancy or undergoing haemodialysis or renal transplantation. Of 100 significantly positive cultures, organisms from 82 grew in the conventional aerobic (+ CO2) bottle, 78 in the conventional anaerobic bottle and 71 in the Malthus bottle. The differences were not statistically significant (p greater than 0.05). The Malthus system detected 83.6% of significantly positive cultures earlier than the comparable conventional bottles while 7.3% positive cultures were detected earlier by the conventional system. When use of the Malthus system was restricted to the hours of 09.00 to 17.30 daily 27.3% positive cultures were detected earlier by the Malthus system and 16.4% were detected earlier by the conventional system. One of the organisms which grew in the Malthus bottle, a contaminating Staphylococcus epidermidis, was not detected by the Malthus system. Instability of electrodes resulted in 26.9% false positive cultures with the prototype Malthus system. Contamination rates in both the Malthus and conventional anaerobic bottles were lower than in the aerobic bottles.

Bacteria↗
PubMed1983

25-hydroxyvitamin D hydroxylation. Evidence for a dioxygenase activity of solubilized renal mitochondrial cytochrome P-450.

Upon solubilization and partial purification, renal mitochondrial P-450 catalyzes both the 1 alpha- and 24-hydroxylations of 25-hydroxyvitamin D3 in the absence of NADPH. Neither 1 alpha,25-dihydroxyvitamin D3 nor 24,25-dihydroxyvitamin D3 is further metabolized by the enzyme. Under similar conditions, P-450 obtained from hepatic microsomes or adrenal mitochondria is inactive as a 25-hydroxyvitamin D3 hydroxylase. Both hydroxylations are heat-sensitive and are inhibited by 1 alpha,25-dihydroxyvitamin D3, 24,25-dihydroxyvitamin, 25,26-dihydroxyvitamin D3, EDTA, menadione, dithiothreitol, and cadmium but not by carbon monoxide. Cumene hydroperoxide does not facilitate either hydroxylation and no lipid peroxides can be detected in the system either prior to or after incubation with the substrate. Based on these data, it is proposed that during these hydroxylations P-450 is acting as a dioxygenase. The first step in the sequence of reactions is postulated to be a P-450-catalyzed formation of a hydroperoxide at carbon 1 of a substrate molecule. This is followed by the 25-hydroxyvitamin D hydroperoxide-supported, P-450-catalyzed hydroxylation of another molecule of substrate at either the 1 alpha or the 24 position. During the cycle 1 alpha,25-dihydroxyvitamin D3 is also generated from the hydroperoxide. From this mechanism, it can be concluded that one form of P-450 is capable of catalyzing the production of both 1 alpha,25-dihydroxyvitamin D3 and 24,25-dihydroxyvitamin D3.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed1983

The effect of case-mix adjustment on admission-based reimbursement.

This paper addresses two questions: (1) Does adjusting for case mix have any effect on prospective admission-based reimbursement? and (2) How does the way in which case type is defined (DRG, ICD9CM, Age, etc) affect reimbursement systems? Data from 20 Maryland hospitals provided the basis for analysis, and the results illustrate how hospital reimbursement is affected under alternative definitions of case type (including no case type), showing highly significant variation. Implications for cost control and existing and proposed prospective reimbursement systems are discussed.

Costs and Cost Analysis↗