In symptomatic men with significant coronary atherosclerosis and normal to moderately elevated serum cholesterol, less progression of coronary atherosclerosis and fewer new cardiovascular events were observed in the group of patients treated with pravastatin than in the placebo group.
A delayed clearance of postprandial lipoproteins from the plasma may play a role in the etiology of premature coronary atherosclerosis. To address this hypothesis, we studied chylomicron (remnant) metabolism in two groups of 20 selected normolipidemic men aged 35-65 years, a group of coronary artery disease (CAD) patients, and a matched control group with documented minimal coronary atherosclerosis. Subjects received an oral fat load supplemented with cholesterol and retinyl palmitate. Plasma samples obtained during the next 24-hour period were analyzed for total as well as d less than 1.019 g/ml and d greater than 1.019 g/ml triacylglycerol, cholesterol, and retinyl ester concentrations. Although both groups of patients responded identically in terms of the appearance of gut-derived lipids in the plasma, CAD patients showed a marked delay in the clearance of retinyl esters as well as in the normalization of plasma triacylglycerol concentrations. Postheparin plasma hepatic lipase activity was significantly lower in the CAD group. Apolipoprotein E phenotype measurements did not reveal marked differences in frequency between both groups. The frequency distribution was not unusual in comparison with the normal Dutch population. The magnitude of the postprandial responses of triacylglycerol and retinyl esters was correlated positively with the fasting levels of plasma triacylglycerol and negatively with high density lipoprotein subfraction 2 cholesterol concentrations. These data indicate that the clearance of postprandial lipoproteins in normolipidemic CAD patients as selected in the present study is delayed as compared with that of controls without coronary atherosclerosis and suggest that postprandial lipoproteins may play a role in the etiology of their disease.
We studied the molecular basis of low hepatic lipase (HL) activity in normolipidemic male patients with angiographically documented coronary artery disease (CAD). In 18 subjects with a lowered HL activity (< 225 mU/mL), all nine exons of the HL gene and part of the promoter region (nucleotides -524 to +7) were sequenced. No structural mutations in the coding part of the HL gene were found, but 50% of the subjects showed a C-to-T substitution at nucleotide -480. Screening for the base substitution in 782 patients yielded an allele frequency of 0.213 (297 heterozygotes, 18 homozygotes). In a group of 316 nonsymptomatic control subjects, the allele frequency was 0.189, which is significantly less than in the CAD patients (P = .035). In the CAD patients, the C-to-T substitution was associated with a lowered lipase activity (heterozygotes -15%, homozygotes -20%). The patients were divided into quartiles on the basis of HL activity. Sixty percent (allele frequency 0.32) of the patients in the lowest quartile (HL activity < 306 mU/mL) had the gene variant against 27% (allele frequency 0.14) in the highest quartile (HL activity > 466 mU/mL). In the noncarriers, but not in the carriers, HL activity was related with plasma insulin, being increased at higher insulin concentration. Homozygous carriers had a significantly higher HDL cholesterol level-than noncarriers (1.13 +/- 0.28 mmol/L versus 0.92 +/- 0.22 mmol/L, P < .02). Our results show that a C-to-T substitution at -480 of the HL promoter is associated with a lowered HL activity. The base substitution, or a closely linked gene variation, may contribute to the variation in HL activity and affect plasma lipoprotein metabolism.
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