Plasma lipids in Nigerian hypertensives.

In this study, the plasma lipids in 50 Nigerian hypertensives and 50 control subjects, matched for age and sex, were estimated by enzymatic colorimetric methods. Generally, the levels of plasma lipids for both controls and subjects were within the normal range. However, there were elevations of plasma total cholesterol (after correcting for the effect of weight), low density lipoproteins and triglycerides in the hypertensives. There was some decrease in the levels of high density lipoproteins (HDL) and cholesterol concentration in hypertensives but this was not statistically significant.

The effects of substrate flow-rate on immobilized urease assays.

Urease (urea aminohydrolase, EC 3.5.1.5) has been immobilized on o-alkylated nylon tubes in an enzymatically active form. The measured activity of the enzyme coil has been shown to be dependent on the flow rate of substrate through it. The apparent Km decreased and V increased as flow rates were increased. It is suggested that diffusional control is responsible for these observations. Their implications in flow-through immobilized enzyme analyses are discussed.

Comparative serum apolipoprotein studies in ischaemic heart disease and control subjects.

We have compared the concentrations of serum lipoprotein apoproteins in 55 ischaemic heart disease (IHD) patients and 116 apparently healthy control subjects by a simple, precise and reasonably sensitive "rocket" electroimmunoassay technique. Apolipoprotein B and apolipoprotein C levels in the vaery low density lipoprotein class and apolipoprotein B in the low density lipoprotein class were significantly lower IHD patients than in control subjects (p < 0.001). Apolipoprotein A levels within high density lipoproteins were markedly lower in a subpopulation of IHD patients compared with age-and sex-matched controls (p < 0.05). Using levels in excess of the 95th percentile of the levels in the healthy control population to delineate "abnormalities", we showed that there were more patients with "abnormalities" when lipoprotein apoprotein measurements were considered than when lipoprotein lipids were considered. The positive correlations between lipoprotein lipids and their apoproteins were in most instances greater in IHD patients than in controls.

Quantitative serum lipoprotein electrophoresis in Nigerians.

In response to the growing demand for lipid profiles in Nigerian patients with suspected ischaemic heart disease, cerebro-vascular accident and hypertension, serum lipoprotein electrophoresis based on ozone-Schiff staining technique and densitometric scanning has been developed. Out of 93 serum samples 80 showed three distinct bands in the electrophoretic patterns; nine showed two distinct bands and four had unusual migration characteristics. Mean percentages of the three bands in the common pattern were 43.5, 22.8, and 33.7 for alpha pre-beta and beta lipoproteins respectively. The relative preponderance of alpha lipoproteins in Africans contrasts with the findings in Europeans. It supports the view that high serum alpha lipoproteins may be protective against ischaemic heart disease in contrast to the atherogenic role of beta lipoproteins.

Serum lipids and lipoproteins in healthy Africans.

Using a simple precipitation technique we observed that the serum concentrations of low density lipoproteins in healthy Africans were less than half the serum concentrations in healthy Europeans. Serum concentrations of lipids and the lipoproteins varied according to the social class of Africans. Serum triglyceride concentrations did not rise with adult age but serum cholesterol concentrations did. Contrary to the findings in Europeans, the proportion of alpha lipoprotein fraction on serum electrophoresis in the Africans was relatively higher than that of beta lipoprotein fraction.

Measurement of the apoproteins of human serum lipoproteins by rocket immunoelectrophoresis.

A method has been developed for assay of apolipoproteins A, B and C in human serum, using rocket immunoelectrophoresis. The technique is reasonably simple, sensitive and precise. The concentrations of apolipoproteins A, B and C in these classes of serum lipoproteins were measured in 116 healthy subjects. Concentrations of apoproteins within very low and low density lipoproteins increased with age but those of high density lipoproteins showed no consistent age trend.

Intravenous fat-tolerance test in ischaemic heart disease and peripheral vascular disease.

1. The intravenous fat-tolerance test and serum lipid and lipoprotein measurements were carried out in ninety-three normal subjects, fifty-one patients with ischaemic heart disease and thirty patients with peripheral vascular disease. 2. The fractional turnover rate of exogenous triglyceride was significantly slower in patients with ischaemic heart disease and in patients with peripheral vascular disease than in normal men. The rate was also slower in normal men than normal women. 3. Serum triglyceride and cholesterol concentrations were higher in both vascular disease groups than in control subjects. 4. The proportion of both groups of patients who had a subnormal fractional turnover rate of exogenous triglyceride was 35%, and 32% of patients had hypertriglyceridaemia in the fasting state; 27% of patients were hypercholesterolaemic. 5. Although the intravenous fat-tolerance test did not provide significantly better discrimination between cardiovascular patients and control subjects than did measurement of serum triglyceride, the results suggest that hypertriglyceridaemia in such patients may be separable into a group in which impaired triglyceride clearance may be partly responsible, and a group in which overproduction of serum triglyceride may be the major mechanism of the hyperlipidaemia.

Lipoprotein concentrations in serum and in biopsy samples of arterial intima: a quantitive comparison.

Lipoprotein concentrations were compared in serum and in samples of arterial intima obtained during cardiovascular surgery. The interval between blood sampling and surgery did not exceed 48 hours. Apolipoproteins B and C, the major proteins of low density lipoprotein (LDL) and very low density lipoprotein (VLDL) respectivity, were detectable by immuno-assay in all arterial specimens. Highly significant positive correlations existed between the levels of lipoproteins in the intima and in serum. In patients with elevated serum VLDL levels (Type IV hyperlipoproteinaemia) arterial concentrations of apolipoproteins B and C were increased about two-fold; in those with raised LDL levels in serum (Type II), with or without concomitant elevation of VLDL levels, the concentration of apolipoprotein B was increased almost 5-fold in the arterial intima. The arterial wall therefore contains lipoproteins or their immunologically-similar metabolites at concentrations which are determined in part by serum lipoprotein levels.