Towards standardisation of pre- and post-analytical variables in the assessment of lipid risk factors for ischaemic heart disease.

A wide disparity exists between statistical and optimal reference ranges for total cholesterol (TC) levels in South Africa. The haphazard downward adjustments by some laboratories over the years have resulted in highly variable and confusing 'normal cholesterol' values. Using essentially the same enzymatic method and equipment the TC upper limits varied by almost 50% (5.7-8.5 mmol/l) in 24 private laboratories, while it ranged from 5.7 mmol/l to 6.7 mmol/l in 6 academic hospital laboratories. The greatest disparity occurred in the lower limits of 'normal' for high-density lipoprotein cholesterol (HDLC), which ranged from 0.45 mmol/l to 1.43 mmol/l. Although triglycerides may not be an independent risk factor for ischaemic heart disease, the upper limit ranged from 1.69 mmol/l to 2.5 mmol/l despite comparable methods and equipment used. Lipid data obtained on approximately 5,000 healthy adults from the Transvaal, Natal and the Orange Free State revealed remarkable similarities to those obtained in the CORIS study. It therefore confirms the applicability of the CORIS epidemiological findings to other westernized groups in different regions of South Africa. This congruency in blood lipid values and methodologies used in different laboratories should also enable all state and private laboratories to use the same age-specific limits for desirable TC and HDLC levels.

Kinetics and in vivo distribution of in-111-labelled platelets and platelet function in familial hypercholesterolaemia.

The kinetics, in vivo distribution and sites of sequestration of autologous In-111-labelled platelets and other platelet function parameters were studied in ten patients with type IIa or IIb familial hypercholesterolaemia and thrombotic complications of atherosclerosis. The in vitro platelet aggregation response to ADP (P = 0.50) and collagen (P = 0.46); binding of fibrinogen to platelets (P = 0.61); and plasma beta-thromboglobulin levels (P = 0.42) of the patients and normal reference subjects did not differ significantly. The in vivo distribution of In-111-labelled platelets at equilibrium was within normal limits, and at the end of platelet life-span the sequestration pattern of labelled platelets in the reticuloendothelial system was also normal (spleen P = 0.31; liver P = 0.54). There was minimal evidence of in vivo platelet activation: only mean platelet lifespan (MPLS), 195 +/- 57 hours (difference between mean MPLS of patients and controls was 25 hours, with a 95% confidence interval from 23 to 31 hours; P = 0.02); mean platelet platelet turnover, 2298 +/- 824 platelets/microliter/hour (P = 0.005); plasma platelet factor 4 (P = 0.02); and the mean circulating platelet aggregate ratio, 0.8 +/- 0.1 (P = 0.02); differed significantly from normal. These results suggest that abnormalities of platelet function and kinetics observed in type II hyperlipoproteinaemia cannot be ascribed wholly to the hyperlipidaemia, but may be induced by the associated atherosclerosis.

Effects of tendamistate on postprandial plasma glucose, free fatty acid and triglyceride levels.

A dose of 400 mg tendamistate or a placebo was given to 10 volunteers in order to investigate its effects on plasma glucose, free fatty acid and triglyceride levels after a porridge meal. Each subject participated in two phases, in each of which they ate porridge prepared from 100 g maize meal together with either placebo or tendamistate 400 mg. Serial blood specimens for plasma glucose determinations were taken up to 3 hours after the meal, and those for free fatty acid and triglyceride determinations up to 14 hours after the meal. Side-effects (flatulence and bulky stools) were not severe and were reported after both treatments. Tendamistate administration significantly attenuated postprandial glycaemia; it had no effect on postprandial triglyceride levels and was associated with a reduction in free fatty acid levels.

Serum zinc levels in pelvic inflammatory disease.

Serum zinc concentrations in 47 patients with acute pelvic inflammatory disease were compared with those of 50 women in a control group. The erythrocyte sedimentation rate, the white cell count and acute-phase protein (alpha 1- and alpha 2-globulin) values were used to confirm or exclude infection among the patients studied. All these values differed significantly in the control and study groups. The mean zinc level in patients with pelvic inflammatory disease was 0.725 +/- 0.154 micrograms/ml and that in the control group 0,862 +/- 0.117 micrograms/ml. This difference was statistically significant (P less than 0.001).

Glycosylated haemoglobin, blood glucose and serum cholesterol levels in diabetics treated with guar gum.

The diet of 10 insulin-dependent diabetics was modified for 3 months by the addition of guar gum to buttermilk rusks. Control of glycaemia was assessed by serial determination of total glycosylated haemoglobin A1. The effect of guar on serum cholesterol levels was noted. Guar gum supplementation failed to improve the long-term diabetic control, but significantly reduced serum cholesterol levels (P less than 0,01). The effect of guar on lipoprotein levels should be investigated more fully.