Search PubMed⌕ Search

Biomedical subjects

R Joseph

Publications and source records attributed to R Joseph.

At least 217 records · Page 12Linked to original sources
PubMed1974

Autolytic formation of protoplasts (autoplasts) of Streptococcus faecalis 9790: release of cell wall, autolysin, and formation of stable autoplasts.

A system for the formation of apparently wall-free protoplasts from exponential-phase cells of Streptococcus faecalis ATCC 9790 in the absence of added lytic enzymes was developed. Exponential-phase cells suspended in 0.04 M ammonium acetate, pH 6.7, 1 mM magnesium acetate, and 0.5 M sucrose become osmotically fragile within 1 to 1.5 h due to the action of the native, autolytic enzyme on the cell wall peptidoglycan. However, maximal cell wall loss occurred much more slowly, being complete only after 3 to 6 h. Under these conditions, the autolytically formed protoplasts (autoplasts) remained intact for prolonged periods (up to 24 h) with less than 5% of their deoxyribonucleic acid, ribonucleic acid, and protein lost during the first 6 h. During dissolution of the cell wall, release of autolytic enzyme to the supernatant fluid began after 60% of the wall was lost. The addition of trypsin to the incubation mixture increased the rate of attainment of osmotic fragility and cell wall loss two- to threefold, apparently due to the activation of the latent form of the autolysin. Electron microscopy was used to confirm cell wall loss and the presence of intact protoplasts at the end of the incubation periods.

Acetates↗
PubMed1973

Peptidoglycan of free-living anaerobic spirochetes.

Electron microscope examination of negatively stained or thin-sectioned cells of Spirochaeta stenostrepta treated with penicillin or lysozyme showed that the peptidoglycan was present as a thin, electron-dense layer adjacent and external to the cytoplasmic membrane. The peptidoglycan was isolated from cells of S. stenostrepta and Spirochaeta litoralis by a procedure including treatments with sodium lauryl sulfate and Pronase. Hydrolysates of the isolated S. stenostrepta and S. litoralis peptidoglycans contained glucosamine, muramic acid, glutamic acid, l-ornithine, and alanine in molar ratios of 0.90:0.85:1.00:1.00:1.40 and of 0.63:0.63:0.99:1.00:1.41, respectively. Determination of N-terminal residues suggested that nearly 50% of the ornithine in S. stenostrepta and S. litoralis peptidoglycans was involved in peptide cross-linkage. The peptidoglycan layer of S. stenostrepta was sensitive to lysozyme and myxobacter AL-1 protease.

Alanine↗
PubMed1972

Fatty acid composition of Spirochaeta stenostrepta.

The fatty acid composition of Spirochaeta stenostrepta consists primarily of saturated, branch-chained fatty acids. Iso-C(15), anteiso-C(15), iso-C(17), and anteiso-C(17) represent 66% of the total fatty acids.

Anaerobiosis↗
PubMed1969

Requirement for coenzyme A in the phosphoroclastic reaction of anaerobic bacteria.

Various bacteria which degrade pyruvate by the phosphoroclastic reaction were examined with respect to the role of coenzyme A (CoA) in this reaction. The strictly anaerobic bacteria, which cleave pyruvate by the phosphoroclastic reaction characteristic of Clostridia, required catalytic levels of CoA for the CO(2)-pyruvate exchange and acetoin-forming portions of the phosphoroclastic reaction. These reactions were reversibly inhibited by the CoA analogue, desulfo-CoA. In contrast, using cell-free extracts of bacteria which degrade pyruvate by the coliform phosphoroclastic reaction (pyruvate formate-lyase), no requirement for CoA could be observed for the formate-pyruvate exchange reaction. It is suggested that CoA serves a regulatory function in the early portion of the clostridal type of phosphoroclastic reaction.

Air↗
PubMed1967

Effect of L-methionine and S-adenosylmethionine on growth of an adenine mutant of Saccharomyces cerevisiae.

A pink, adenine-requiring yeast utilized adenine, hypoxanthine, or S-adenosylmethionine (SAM), in quantities up to 3 mumoles per 100 ml of medium, as equivalent sources of purine for cell growth, but not methylthioadenosine or S-adenosylhomocysteine. Utilization of SAM for growth was inhibited by the presence of l-methionine in quantities greater than 0.6 mumole per 100 ml of medium. However, 6 mumoles of l-methionine had no effect on growth when adenine or hypoxanthine was the source of purine. These sources also reversed the inhibitory effects of 6 mumoles of the amino acid on the utilization of SAM. The presence of 400 mumoles of the amino acid resulted in some inhibition of growth when the organisms were grown with adenine, hypoxanthine, or adenine plus SAM but had no effect on the total uptake of adenine-8-(14)C. Studies on the uptake of radioactivity from a mixture of SAM-adenine-8-(14)C and (3)H-labeled SAM-methyl indicated that these components were taken into the cells at different rates which were altered by the presence of l-methionine. The fixation of (35)S from (35)S-labeled adenosylmethionine into the cells was inhibited by the presence of the amino acid. The cells synthesized and accumulated SAM in the presence of 400 mumoles of l-methionine plus adenine even when exogenous SAM was supplied. Approximately 47% of radioactivity fixed from exogenous SAM-adenine-8-(14)C and 12% from (3)H-labeled SAM-methyl were found in reisolated SAM.

Adenine↗
PubMedDate not supplied

Fournier's gangrene: CT findings.

Fournier's gangrene is an uncommon gas-forming infection of the scrotum which if not recognized early and treated appropriately may be fatal. In three patients recently seen at our institution, computed tomography (CT) was instrumental in establishing the correct diagnosis and determining the extent of the infectious process prior to surgery. The imaging findings at CT and its differential diagnosis are illustrated. A brief review of the current theories of pathogenesis of this interesting entity is presented.

Aged↗
PubMedDate not supplied

Interference by nonsteroidal anti-inflammatory drugs in EMIT and TDx assays for drugs of abuse.

Fourteen nonsteroidal anti-inflammatory drugs were evaluated for interference in EMIT and TDx assays for drugs of abuse. Only tolmetin demonstrated significant interferences in the EMIT assay. Urine samples that contained high concentrations of tolmetin (1800 mg/L) had characteristic high molar absorptivity at the wavelength used in EMIT assays (340 nm). Consequently, EMIT analysis of samples resulted in instrument error alarms on a Hitachi 704 instrument and depressed milliabsorbance values (delta A) relative to calibrators. Similar results were obtained with urine samples collected from an arthritic patient after the administration of 200 and 400 mg of tolmetin. When tolmetin samples were mixed with drugs of abuse, depressed delta A values were noted in all assays. Samples containing opiates and cannabinoids tested negative, and instrument error alarms were produced with samples that contained amphetamines. A gas chromatographic-mass spectrometric (GC-MS) assay for benzoylecgonine in the presence of tolmetin was successful, and no interferences were noted. Similar interferences by tolmetin were not observed in TDx assays, probably because of the different wavelength (525 nm) used in this assay. However, a potential for false-positive results in the TDx benzodiazepine assay was noted for urine samples containing high concentrations of fenoprofen, flurbiprofen, indomethacin, ketoprofen, and tolmetin. Generally, it was concluded that the presence of tolmetin in urine samples could lead to the production of unacceptable results by the EMIT assay for drugs of abuse. However, TDx and GC-MS assays were useful alternatives for the analysis of urine samples suspected of containing tolmetin.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMedDate not supplied

Thyroid releasing hormone inhibits testosterone metabolism by rat prostate in vitro.

A method involving thin layer chromatography (TLC) was developed to assess 5 alpha-DHT-reductase activity in rat ventral prostate, in terms of the amount of testosterone metabolised to its main 5 alpha-reduced compound, dihydrotestosterone (DHT). Using this method an in vitro study was carried out to determine 5 alpha-DHT reductase activity in the rat ventral prostate as modulated by thyroid releasing hormone (TRH). The study revealed a decrease in the enzyme activity with increasing doses of TRH, as shown by a decrease in the extent of reduction of testosterone to DHT. The ratios of the counts for DHT and testosterone however did not show any dose related effect.

5-alpha Reductase Inhibitors↗
PubMedDate not supplied

Cerebral blood flow asymmetries in headache-free migraineurs.

Regional cerebral blood flow (rCBF) asymmetries were studied in controls and patients with common and classic/complicated migraine using 133Xe inhalation with 8 homologously situated external collimators over each cerebral hemisphere. Migraine patients as a group more frequently had posterior rCBF asymmetries than controls (p less than 0.03). Although there were no differences in the number of anterior rCBF asymmetries, migraine patients had 2 or more asymmetric probe pairs more often than controls (p less than 0.02). The posterior rCBF asymmetries, consistent with the site of activation of many migraine attacks, may be related to more labile control of the cerebral circulation.

Adult↗