Apolipoprotein E polymorphism and serum concentration in Alzheimer's disease in nine European centres: the ApoEurope study. ApoEurope group

As part of the ApoEurope Project, apolipoprotein E (apo E) common polymorphism and serum concentration were determined in 489 Alzheimer's disease patients and 429 controls. Patients and controls were recruited through nine centres in eight European countries. Age, sex ratios and education levels of both case and control populations were similar, although discrete differences appeared between centres. The prevalence of the epsilon4 allele was higher in Alzheimer's disease than in controls (increased by 140%), while serum apo E concentration was lower by 11.2% (p<0.001). In addition, serum total cholesterol and triglyceride concentrations were lower in Alzheimer's disease (p<0.001), while that of apo Al was not affected. The decrease in serum apo E concentration was not accounted for by the epsilon4 allele, age or gender, suggesting that apo E concentration might represent an additional risk factor for Alzheimer's disease, complementary and independent of the epsilon4 allele. Further analysis will be aimed at determining whether the quantitative link between apo E concentration and Alzheimer's disease occurs through the effect of apo E genotype on lipid parameters or by other mechanisms.

Atherogenic lipid profile in elderly patients with ischaemic cerebrovascular disease

The significance of the link between plasma cholesterol concentrations and risk of cerebrovascular disease (CVD) in the elderly is still debated. In a case-control study we found that elderly patients with ischaemic CVD have an atherogenic lipid profile, despite having low or normal total cholesterol concentrations.

Lovastatin decreases de novo cholesterol synthesis and LDL Apo B-100 production rates in combined-hyperlipidemic males

The effect of lovastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity, on the kinetics of de novo cholesterol synthesis and apolipoprotein (apo) B in very-low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), and low-density lipoprotein (LDL) was investigated in five male patients with combined hyperlipidemia. Subjects were counseled to follow a Step 2 diet and were treated with lovastatin and placebo in randomly assigned order for 6-week periods. At the end of each experimental period, subjects were given deuterium oxide orally and de novo cholesterol synthesis was assessed from deuterium incorporation into cholesterol and expressed as fractional synthesis rate (C-FSR) and production rate (C-PR). Simultaneously, the kinetics of VLDL, IDL, and LDL apo B-100 were studied in the fed state using a primed-constant infusion of deuterated leucine to measure fractional catabolic rates (FCR) and production rates (PR). Drug treatment resulted in significant decreases in total cholesterol (-29%), VLDL cholesterol (-40%), LDL cholesterol (-27%), and apo B (-16%) levels and increases in HDL cholesterol (+13%) and apolipoprotein (apo) A-I (+11%) levels. Associated with these plasma lipoprotein responses was a significant reduction in both de novo C-FSR (-40%; P = .04) and C-PR (-42%; P = .03). Treatment with lovastain in these patients had no significant effect on the FCR of apoB-100 in VLDL, IDL, or LDL, but resulted in a significant decrease in the PR of apoB-100 in IDL and LDL. Comparing the kinetic data of these patients with those of 10 normolipidemic control subjects indicates that lovastatin treatment normalized apoB-100 IDL and LDL PR. The results of these studies suggest that the declines in plasma lipid levels observed after treatment of combined hyperlipidemic patients with lovastatin are attributable to reductions in the C-FSR and C-PR of de novo cholesterol synthesis and the PR of apoB-100 containing lipoproteins. The decline in de novo cholesterol synthesis, rather than an increase in direct uptake of VLDL and IDL, may have contributed to the decline in the PR observed.

Impact of hydrogenated fat consumption on endogenous cholesterol synthesis and susceptibility of low-density lipoprotein to oxidation in moderately hypercholesterolemic individuals

The effects of replacing corn oil with corn oil margarine in stick form on endogenous cholesterol synthesis and susceptibility of low-density lipoprotein (LDL) to oxidation were assessed in 14 middle-aged and elderly men and women aged 63 +/- 12 years (mean +/- SD) with moderate hypercholesterolemia (mean LDL-cholesterol [LDL-C], 4.24 +/- 0.59 mmol/L at the time of recruitment). Subjects consumed each of two diets for 32-day periods, one enriched in corn oil, which contained 30% of energy as fat (7% saturated fatty acid [SFA], 9% monounsaturated fatty acid [MUFA] [0.4% 18:1n9 trans], and 11% polyunsaturated fatty acid [PUFA]) and 85 mg cholesterol/4.2 MJ, and one enriched in stick corn oil margarine, which contained 30% fat (8% SFA, 12% MUFA [4.2% 18:1n9trans], and 8% PUFA) and 77 mg cholesterol/4.2 MJ. Both diets were isocaloric and supplied by a metabolic research kitchen. Mean total cholesterol levels were lowest (P = .039) when subjects consumed the corn oil-enriched diet (5.01 +/- 0.51 mmol/L) as compared with the margarine-enriched diet (5.30 +/- 0.58 mmol/L). LDL-C levels were 3.24 +/- 0.51 and 3.50 +/- 0.54 mmol/L when subjects consumed corn oil-and margarine-enriched diets, respectively (P = .058). There were no significant differences in high-density lipoprotein cholesterol (HDL-C) or triglyceride concentrations between the two experimental periods. Consumption of the margarine-enriched diet versus the corn oil-enriched diet tended to result in lower cholesterol fractional synthetic rates ([C-FSRs] 0.0466 +/- 0.0175 and 0.0668 +/- 0.0298, respectively, P = .080) and cholesterol absolute synthetic rates ([C-ASRs] 1.1761 +/- 0.5375 and 1.6954 +/- 0.8685, respectively, P = .092); however, differences did not reach statistical significance. Consumption of the margarine-enriched diet versus the corn oil-enriched diet resulted in a significantly higher concentration of alpha-tocopherol in both plasma and LDL(P = .004 and P = .011, respectively). LDL particle size tended to be smaller after subjects consumed the margarine-enriched diet versus the corn oil-enriched diet (P = .103). Susceptibility of LDL to oxidation was similar after consumption of the corn oil- and margarine-enriched diets. These data suggest that an increased rate of endogenous cholesterol synthesis did not contribute to the higher plasma cholesterol concentrations during the period when subjects consumed the margarine-enriched diet. Therefore, the increase in cholesterol concentration resulting from margarine consumption was likely attributable, at least in part, to a decreased catabolic rate of cholesterol. Additionally, susceptibility of LDL to in vitro oxidation was not altered by consumption of hydrogenated fat.

Impact of age on the metabolism of VLDL, IDL, and LDL apolipoprotein B-100 in men

Levels of plasma very low density lipoprotein (VLDL) and low density lipoprotein (LDL) constituents increase with age. In an attempt to further define the mechanisms responsible for these changes, kinetic studies of VLDL and LDL apolipoprotein (apo) B-100 were carried out in 19 normolipidemic male subjects with plasma total cholesterol and triglyceride levels below the 90th percentile whose ages ranged from 24 to 73 years. Subjects were maintained on standardized diets consisting of 47-49% of calories as carbohydrate, 15% protein, and 36-40% fat (15-17% saturated, 15-17% monounsaturated, 6% polyunsaturated) with 150 mg cholesterol/1000 kcal. At the end of the diet period, the metabolism of apoB-100 within VLDL, intermediate density lipoprotein (IDL), and LDL was studied in the fed state using a primed-constant infusion of [2H3]leucine. Data were fit to a multicompartmental model to determine residence times and production rates of apoB-100 in each fraction. There were significant positive correlations between age and VLDL, IDL, and LDL apoB-100 concentrations (r = 0.50, 0.62, and 0.69; P = 0.03, 0.004, and 0.001, respectively). There was a positive correlation between age and the production rate of VLDL apoB-100 (r = 0.50, P = 0.03), but there was no significant relationship between age and either IDL or LDL apoB-100 production rates. Age was also positively correlated with the residence time of LDL apoB-100 (r = 0.68 P = 0.001). Our data suggest that the age-associated increase in VLDL apoB-100 is due to an increased production rate of this constituent, whereas the age-associated increase in LDL apoB-100 is due to an increased residence time of these particles in plasma.

Determination of Lp(a) and APO(a) in an Italian population

Plasma lipoprotein(a) [Lp(a)] levels were determined in an Italian population subdivided according to age and sex. The distribution of plasma Lp(a) levels was highly skewed, with 75% of the subjects having less than 10 mg/dl. No significant differences were found in the plasma Lp(a) levels of the two age groups, but women had significantly higher levels than men. There was no significant correlation between Lp(a) levels and the other lipid and lipoprotein parameters studied, with the exception of a weak correlation between Lp(a) levels and both total cholesterol and low density lipoprotein-cholesterol in younger women. Apoprotein(a) phenotyping was performed in about one-third of the population; an inverse relationship between the molecular weight of the different isoforms and plasma concentrations of Lp(a) was observed.