Biomedical subjects
Publications and source records attributed to W Chan.
Often used as an oral analgesic in the management of pain associated with traumatic hyphema, aspirin has an inhibitory effect on the blood clotting mechamism by its action on platelets. We carried out a retrospective study of patients with traumatic hyphema treated with aspirin and showed that the incidence of rebleeding significantly increased with aspirin administration.
The chronically uremic rat has been used as a model to study amino acid metabolism in uremia. Uremic rats fed low protein diets (6% casein) survived longer than uremic rats receiving either higher levels of dietary protein or a low protein diet supplemented with a mixture of nonessential amino acids. Alterations in plasma amino acid levels were observed in the uremic rats and were similar to those found in patients with renal failure. Plasma concentrations of citrulline, free tryptophan, glycine and the methylhistidines were increased and levels of serine, ornithine, lysine, total tryptophan, tyrosine, and the tyrosine-phenylalanine ratio were reduced. The metabolic basis of the altered tyrosine-phenylalanine ratio in plasma was studied. Tyrosine aminotransferase (TAT) and phenylalanine hydroxylase (PHL) activity were normal in the liver, but renal PHL activity of was decreased as compared to control rats. Tissue concentrations of citrulline were also found to be raised in liver and muscle of uremic rats. The activity of ornithine transcarbamoylase, was reduced in the liver and arginine synthetase activity was decreased in the kidneys of uremic rats. Thus elevated citrulline levels in uremic tissue appear to be caused by a decrease conversion of citrulline to arginine in the kidney. Preliminary studies of tryptophan metabolism in uremic rats have shown elevated brain levels of 5-hydroxyindoleacetic acid and increased hepatic tryptophan oxygenase activity. Increased plasma amine levels were associated with altered activities of monoamine oxidase and diamine oxidase in kidney and other tissues.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
There is a need for more detailed information on the relative merits of the culture and direct sputum smear examination methods, separately and in various combinations, using one or more sputum specimens. The efficiency and relative cost of different bacteriological measures for the detection of cases of pulmonary tuberculosis, in the conditions of the Singapore tuberculosis control programme, are demonstrated. The findings provide guidance for deciding how, and in what order, these bacteriological measures should be used, and may assist planners and executives of national tuberculosis control programmes in the rational commissioning of laboratory facilities that already exist or are to be established.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
This study investigates sexual maturity as a predictor of resting blood pressures independent of other known predictors, in 179 boys and 204 girls 11-16 years of age from the Heartfelt Study. The sample included youth of African (n = 140), Mexican (n = 117), and European and "other" (n = 126) backgrounds. Sexual maturity was assessed during clinical examination of three standard indicators for each sex. Systolic and diastolic blood pressures were higher in children of maturity stages IV and V, compared to stages I-III, in each gender/ethnic group (P < 0.01 in almost all groups). Boys and girls advanced in sexual maturity for their age group, had significantly higher systolic blood pressures (but not diastolic) than the less advanced in linear models that included height, body mass index (BMI), ethnicity, and age as co-predictors. Diastolic blood pressures were predicted by height in boys and by age and the BMI in girls. This analysis, using a very conservative approach, suggests that sexual maturity provides important and independent information on systolic blood pressure in adolescents. Further investigation of its role in 24-hr blood pressures and in blood pressures taken during physical and emotional stress, is recommended.
Hostility, a phenomenon that has been linked to cardiovascular disease and all-cause mortality, is often measured by the Cook-Medley hostility (Ho) scale. Although there is an adolescent version of the Ho scale, it has had little testing with only Anglo-American samples. This pilot study tested the reliability and validity of the adolescent version of the Ho scale with a multiethnic sample of adolescents. Sixty adolescents participated. Reliability was measured using Chronbach's alpha. The Ho scale was correlated with the Speilberger State-Trait Anger Expression Inventory (1988) scales to determine concurrent validity. A factor analysis assessed construct validity; content validity was assessed by analyzing tape-recorded descriptions of a circumstance that provoked anger, as remembered by each adolescent. Internal consistency reliability was .75. The hostility measure was most highly correlated with anger expression (r = .62, p = .000) and trait anger (r = .50, p = .000). The factor analysis generated three factors (suspicious alienation, cynical aggression and justified mistrust), that accounted for 34.5% of the variance. The content analysis resulted in five anger-provoking themes: aggression, unfulfilled personal expectations, mistrust/lying, criticism of effort, and rejection. The majority of items in the scale (74%) were related to one of the themes.
Tissue samples from 623 hogs suspected of having received antibiotic treatment were collected at federally-inspected abattoirs in Manitoba and submitted for analysis from October 1987 to March 1988. Initially, samples were screened by a multi-residue thin layer chromatography/bio-autography method, but, during the final two months of the investigation, analysis was restricted to a quantitative high performance liquid chromatography method for tetracycline antibiotics only. Sixteen animals (3%) were found with detectable tissue levels of chlortetracycline ranging from 0.10 to 1.38 ppm. One hundred thirty-eight animals (22%) were found with detectable tissue levels of oxytetracycline ranging from 0.05 to 2.07 ppm. Comparison of these levels with previously published values suggested that some producers were administering tetracyclines at therapeutic levels without observing the seven-day withdrawal period. The data generated by this study provided information for use by regulatory officials at Health and Welfare Canada in establishing specific tolerance levels for residues of the tetracycline antibiotics in animal tissue; previously, a zero tolerance had been in effect. During the study, only one hog had tetracycline residues in muscle which would have exceeded the current tolerance levels.