Biomedical subjects
Publications and source records attributed to A C Asmal.
The HLA antigens of 57 South African negroes with juvenile-onset, insulin-dependent diabetes were determined. The frequency of B8 was increased (29.8% VS 13.9%) as was the frequency of B14 (17.5% vs 6.1%). The frequency of patients with either one of these cross-reactive antigens was significantly increased after correction for the number of antigens tested (45.6% VS 19.2%, P (corrected) < 0.005).
The release of an endogenous 'prostacyclin-like' substance from aortic strips of 8 male Wistar rats of the New Zealand genetically hypertensive strain (GH) was compared with that of 8 weight, age and sex matched normotensive Wistar control rats. The amount of 'prostacyclin-like' substance released by the aortic strips into tris buffer, under the influence of mechanical stimulation, was measured by its ability to inhibit human platelet aggregation as compared to the inhibitory effect of standard prostacyclin sodium salt. It was shown that generation of this substance increased with incubation time and that a significantly greater amount was produced by GH rats.
The HLA antigens of 44 Asian Indians with juvenile-onset, insulin-dependent diabetes were determined. The frequency of HLA-B8 was increased but that of HLA-B15 was not. There was a significant increase in the frequency of some of the subdivisions of B5.
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The antihypertensive efficacy and safety of guanabenz were evaluated against clonidine in two groups of 18 patients with uncomplicated essential hypertension. Both compounds reduced systolic and diastolic blood pressure at the doses used, whether pressures were measured in the supine or standing positions. Side-effects, such as dry mouth and drowsiness, were similar in both groups of patients. No postural hypotension occurred.
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Twenty-one essential hypertensives were randomly treated with Aldactone, acebutolol or a combination of the two drugs. Statistically significant falls in systolic and diastolic pressures were demonstrated during treatment with Aldactone 100 mg daily, also when acebutolol and Aldactone 200 mg daily were administered. When the combination of Aldactone and acebutolol was given, diastolic pressures were lowered to a greater degree than seen with individual treatments.
Haemodynamic effects of intravenous indoramin (5-20 mg) were measured in ten healthy volunteers. Slight falls in arterial and central venous blood pressures were noted but no significant changes in heart rate, right atrial pressure, cardiac output or derived values occurred, except for a fall in peripheral vascular resistance in three cases. An increase in skin blood flow to the feet was observed. An attempt was made to determine the mechanisms of these responses and it was concluded that the drug was an alpha adrenoceptor blocking agent which appeared to act preferentially on those receptors controlling blood flow to the skin of extremities.
The human forearm technique was employed to determine changes in plasma levels and peripheral fluxes of TG, FFA and glycerol in a group of insulin independent diabetics before and after administration of sodium pentosan polysulphate. The forearm technique is based on simultaneous sampling of arterial and venous blood, and forearm flow measurement. Sodium pentosan is a heparinoid, hypolipidemic agent. Before drug administration it was observed that there was net TG uptake, and net glycerol and FFA release across the forearm. Following its injection, triglyceride uptake in the forearm progressively decreased. Sixty minutes after drug administration there was a release of TG into the circulation. Similarly, following sodium pentosan, glycerol release also decreased and culminated in eventual net glycerol uptake from the circulation. The release of TG showed significant correlations with the uptake of glycerol. As the phenomenon of net TG release was noted in more than one third of all significant exchanges across the forearm, these findings raise the possibility that TG release might, in part, contribute to the pathogenesis of diabetic hyper-triglyceridemia.
The efficacy of single daily doses of acebutolol, alone or combined with chlorexolone, was investigated in a group of 20 ambulant patients with uncomplicated hypertension of mild-to-moderate severity. severity. Patients were seen at fort-nightly intervals when doses were adjusted. Blood pressure was measured in all instances at 2 and 8 hours after medication, and after it had stabilized, at 26 hours after the last dose. The results indicate that a single dose of acebutolol alone produces significant lowering of supine and erect blood pressures for 24 hours (P less than 0,005). Combining chlorexolone with acebutolol does not improve the hypotensive effect of the beta-blocker significantly, but makes a smaller dose effective.
A 35-year-old patient with Sheehan's syndrome presented with hypothyroidism and hypo-adrenalism despite having received treatment with regular daily L-thyroxine (0,3 mg) and prednisone (30 mg) for the preceding 12 months. Replacement of the prednisone with 37,5 mg cortisone acetate resulted in satisfactory control of the disease. The observations suggest that large doses of prednisone may interfere with thyroxine treatment.
Some metabolic and haemodynamic responses to intravenous prostaglandin (PG) were studied in five healthy male volunteers, aged 27-40. Subjects, who fasted overnight, rested supine for for 30 min before any measurements were made. Control pulse rate and arterial blood pressure were recorded and 20ml venous blood drawn for analysis. Intravenous infusion of PGE2 5 microgram/min then began and was continued for 15 min; the dose was then increased to 7.5 microgram/min. Measurements were made during the infusion at 15 and 30 min and also 15 min after infusion was stopped. Pulse rate increased but blood pressure was unaffected by the infusion. Glycerol and FFA levels rose, whereas lactate and pyruvate levels fell during the infusion. The rise in glycerol level was significant at 30 min. The changes recorded were slight in clinical terms but the study provides a baseline for the screening of other PG analogues.
Metabolic cataracts in diabetic patients usually develop within the first 3 years of the disease and cause little or no visual disability, but may progress to blindness. We report our findings in 3 patients who previously had normal vision and who presented with virtual blindness from cataract formation at the time of detection of their diabetes.
Lungs of normotensive and genetically hypertensive (GH) albino rats were perfused in stiu with 5 ml/min Krebs solutuion containing 100 ng/ml PGE2 or F2alpha. Inactivation rates of 76,0 ng PGF2 alpha and 146,3 ng PGE2/g dry wt. lung/min were recorded for GH rats. Values for normotensive controls were 191,2 and 226,1 ng/g/min.
Glucose turnover rate, glucose oxidation and lactate production from glucose were investigated in 5 obese subjects using the primed infusion technique, before and four weeks after a course on benfluramate therapy. All subjects lost weight on the drug. Mean glucose turnover rate, but not CO2 and lactate production increased after treatment. The changes in metabolism appear to reflect the combined effects of weight loss and drug action.
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Evidence is presented to show that the classical diagnosis of disturbances in lipid metabolism in terms of lipoprotein phenotypes should now be replaced by a more simple one based on evaluation of plasma lipids alone. This is because of the chemical heterogeneity of the lipoproteins, the clinical, biochemical, pathogenic and genetic heterogeneity of hyperlipoproteinaemias, and the questionable value of 'typing' of the secondary disorders.