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Biomedical subjects

R Shaw

Publications and source records attributed to R Shaw.

At least 127 records · Page 7Linked to original sources
PubMed1985

Pulmonary Mycobacterium tuberculosis in acquired immune deficiency syndrome.

A case of pulmonary infection with Mycobacterium tuberculosis in a patient with the acquired immune deficiency syndrome (AIDS) was studied. Diagnosis of AIDS was confirmed by the finding of pulmonary M tuberculosis with oral and oesophageal candidiasis accompanied by characteristic immunological changes with evidence of infection with human T cell lymphotropic virus III. Treatment of this patient was complicated by an unusual drug interaction between rifampicin and ketoconazole, leading to subtherapeutic serum concentrations and poor clinical response to treatment. Intravenous treatment was more effective than oral treatment. This drug interaction should be studied in greater detail as ketoconazole and rifampicin may be used together to treat patients with candidiasis and infection with M tuberculosis.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Assay of mutagens in aqueous fecal extracts with a modified ames Salmonella test.

Mutagenicity with Salmonella strain TA 100 can be determined by an island test in which only an isolated portion of a pour plate is spotted with a sample. The magnitude of the ratio of the numbers of revertant colonies on the treated and untreated parts of the plate reflects the potency of the mutagen. Five of six chemicals tested yielded statistically significant and generally linear dose-response curves. Minimum detectable mutagenic doses for four compounds calculated from the dose-response curves showed that the island test generally required less material for detection of mutagenicity than the liquid pre-incubation procedure. The island method was primarily designed to test the mutagenicity of aqueous extracts of human stool samples. Dose-responses were obtained for six such samples, and in two samples the amount of material needed for a positive response was significantly less than that required in the liquid pre-incubation method.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1984

Interrelationship between differentiation and malignancy-associated properties in glioma.

The phenotypic expression of cells derived from human anaplastic astrocytomas, rat glioma, normal human adult and foetal brain tissue have been examined for differentiated and malignancy-associated properties. Glial fibrillary acidic protein (GFAP), high affinity glutamate and gamma-amino butyric acid (GABA) uptake and glutamine synthetase were used as indicators of astroglial differentiation. Plasminogen activator and tumour angiogenesis factor were the malignancy-associated markers. The normal adult brain-derived lines showed some differentiated astroglial features and expressed low levels of the malignancy-associated properties. The foetal cultures contained highly differentiated astroglia while the glioma lines showed considerable phenotypic heterogeneity from highly differentiated to undifferentiated. The least differentiated glioma cells exhibited the highest plasminogen activator activities. The density-dependent control of phenotypic expression was also investigated. High affinity GABA uptake, and GFAP in rat C6 glioma cultures, increased with increasing monolayer cell density, events probably mediated by an increase in the formation of cell-cell contacts at confluence. Plasminogen activator activity decreased with increasing cell density.

Adult↗
PubMed1982

Prognostic significance of angiographically documented left ventricular aneurysm from the Coronary Artery Surgery Study (CASS).

In order to evaluate the prognosis of medically treated patients with angiographically defined left ventricular aneurysm the data available from 1,136 patients with aneurysm (7.6 percent) from 15,019 patients with coronary artery disease in the Coronary Artery Surgery Study (CASS) registry were analyzed. Prior myocardial infarction, reduced ejection fraction, absence of angina and evidence of congestive heart failure were more commonly present in patients with aneurysm. The cumulative survival rates of medically treated patients at 1, 2, 3 and 4 years were 90, 84, 79 and 71 percent, respectively. The Cox analysis of survival indicated that the following variables predicted outcome: age, residual left ventricular function as assessed with angiography, left ventricular end-diastolic pressure, functional impairment due to congestive heart failure, number of vessels diseased, mitral regurgitation and S3 gallop. When survival was stratified for similar degrees of left ventricular dysfunction and functional impairment there was no difference between the survival of patients with aneurysm and that of registry patients without aneurysm. The data from this large population study indicate that the survival of patients with left ventricular aneurysm is better than previously recognized. The mortality in this group is primarily related to age, left ventricular function and clinical severity of heart failure. The presence of an aneurysm does not independently alter survival.

Coronary Angiography↗
PubMed1982

Inhibition of two mitochondrial enzymes by gold (III) halo complexes. Evidence for a binding mechanism.

Fumarase (EC 4.2.1.2) and mitochondrial L-malate dehydrogenase (EC 1.1.1.37) were both inhibited by NaAuCl4 and KAuBr4. The inhibition for both was measured as a function of gold complex concentration and aquation time, and the NaAuCl4 inhibition was also measured in the presence of 0.15 M NaCl. Regeneration of the enzyme activity after NaAuCl4 inhibition using L-cysteine, L-methionine and NaCN was also investigated. Sodium dodecyl sulfate (SDS) acrylamide gel electrophoresis and amino acid analysis was performed on the NaAuCl4 inhibited enzymes as well as on ribonuclease A (EC 3.1.26.2), lysozyme (EC 3.2.1.17) and liver alcohol dehydrogenase (EC 1.1.1.1). It was observed that the inhibition was proportional to the gold complex concentration but decreased markedly after aquation of the complex. In the presence of NaCl the initial rate of inactivation is essentially unaffected unless the complex has been aquated and then the initial rate is increased. Gel electrophoresis on gold complex-enzyme mixtures show polymerization for ribonuclease and lysozyme and amino acid analysis indicates that no oxidation has taken place. From these results, a binding mechanism is postulated for the inhibition of the dehydrogenases by direct displacement of a halide ligand, probably by two groups on the enzyme, at least one of which may be a sulfur containing acid.

Amino Acids↗
PubMed1981

Primary malignant melanoma of the esophagus.

Three cases of primary malignant melanoma of the esophagus are presented with emphasis on the gross and histopathologic features. Grossly, the tumors tended to be polypoid with a smooth predominantly intact overlying mucosa. Microscopically a junctional lentiginous growth pattern was characteristic as well as a tendency to expand and fill the submucosa without invading the muscularis. A given tumor invariably was more extensive than grossly suspected and the lateral junctional spread was striking in two of the cases. Primary malignant melanoma should be included in the preoperative differential diagnosis of radiographically unusual esophageal tumors, particularly if the lesion is polypoid. Because of the potentially widespread intramucosal component, surgical treatment of esophageal melanoma required a radical procedure with a far greater margin than for the usual squamous cell carcinoma. Intracavitary radiotherapy may be a useful form of adjuvant therapy in selected patients.

Aged↗
PubMed1981

Comparison of three anaesthetic scavenging devices using cuffed and noncuffed nasal endotracheal tubes during dental anaesthesia.

During maxillofacial and oral surgery the effect of three anaesthetic scavenging devices used with cuffed and non-cuffed endotracheal tubes was investigated. All the devices produced reductions in nitrous oxide concentrations in the breathing zone and peripheral air, ranging from 36% to 76%. Of the three devices evaluated, the Stellenbosch valve produced the greatest reduction in pollution compared with the control.

Air Pollution↗
PubMed1981

A simple air sampling technique for monitoring nitrous oxide pollution.

A simple, inexpensive device for the continuous low-flow sampling of air was devised to permit monitoring of pollution by gaseous anaesthetics. The device consisted of a water-filled Perspex cylinder in which a double-walled flexible-film gas sample collection bag was suspended. Air samples could be aspirated into the collection bag at flow rates of as low as 1 ml min-1 by allowing the water to drain from the cylinder at a controlled rate. The maintenance of sample integrity with aspiration and storage of samples of nitrous oxide in air at concentrations of 1000, 100 and 30 p.p.m. v/v was examined using gas chromatography. The sample bags retained a mean 94% of the nitrous oxide in air samples containing nitrous oxide 25 p.p.m. over a 72-h storage period.

Air Pollutants↗