Terho Lehtimäki

Disturbed cellular cholesterol homeostasis may lead to accumulation of cholesterol in human atheroma plaques. Cellular cholesterol homeostasis is controlled by the sterol regulatory element-binding transcription factor 2 (SREBF-2) and the SREBF cleavage-activating protein (SCAP). We investigated whole genome expression in a series of human atherosclerotic samples from different vascular territories and studied whether the non-synonymous coding variants in the interacting domains of two genes, SREBF-2 1784G>C (rs2228314) and SCAP 2386A>G, are related to the progression of coronary atherosclerosis and the risk of pre-hospital sudden cardiac death (SCD). Whole genome expression profiling was completed in twenty vascular samples from carotid, aortic and femoral atherosclerotic plaques and six control samples from internal mammary arteries. Three hundred sudden pre-hospital deaths of middle-aged (33–69 years) Caucasian Finnish men were subjected to detailed autopsy in the Helsinki Sudden Death Study. Coronary narrowing and areas of coronary wall covered with fatty streaks or fibrotic, calcified or complicated lesions were measured and related to the SREBF-2 and SCAP genotypes. Whole genome expression profiling showed a significant (p = 0.02) down-regulation of SREBF-2 in atherosclerotic carotid plaques (types IV-V), but not in the aorta or femoral arteries (p = NS for both), as compared with the histologically confirmed non-atherosclerotic tissues. In logistic regression analysis, a significant interaction between the SREBF-2 1784G>C and the SCAP 2386A>G genotype was observed on the risk of SCD (p = 0.046). Men with the SREBF-2 C allele and the SCAP G allele had a significantly increased risk of SCD (OR 2.68, 95% CI 1.07–6.71), compared to SCAP AA homologous subjects carrying the SREBF-2 C allele. Furthermore, similar trends for having complicated lesions and for the occurrence of thrombosis were found, although the results were not statistically significant. The results suggest that the allelic variants (SREBF-2 1784G>C and SCAP 2386A>G) in the cholesterol homeostasis regulating SREBF-SCAP pathway may contribute to SCD in early middle-aged men.

The study subjects were from the Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD). The study protocol was approved by the Research Ethics Committee of the University of Kuopio. A total of 2682 men from Eastern Finland, aged 42, 48, 54, or 60, were examined from 1984 to 1989. A DNA sample was available for 1263 of the men. A subpopulation of 480 men, which consisted of 160 men who developed AMI between the years 1985 and 1997, and two matched controls for each of them, was selected for this study. The average follow up time was nine years. To ensure the comparability of the control subjects, they were drawn from the same cohort (KIHD) as the cases. The controls were matched according to age, smoking, dietary iron, dietary saturated fatty acids, dietary cholesterol, and hair mercury content. In addition, examination year and month and the place of residence were identical for each case and the corresponding control. Because of inadequate blood samples, 94 of the men were excluded, leaving 386 men (126 men with AMI and 260 controls) for the final analysis. All participants gave written informed consent.

Background Oxidised low‐density lipoprotein (ox‐LDL) is a determinant of impaired coronary function and oestrogens inhibit its formation probably throughout genetically‐variable oestrogen receptor 1 (ESR1) in artery wall. We hypothesized that the ESR1 polymorphism might influence coronary function and reactivity as measured by positron emission tomography (PET), which allows the detection of coronary dysfunction before appearance of angiographic lesions. Materials and methods Fifty‐one healthy young men (aged 35 ± 4 years), with normal or slightly‐elevated serum cholesterol, underwent PET with intravenous adenosine. ESR1 PvuII genotypes P/P, P/p, and p/p in addition to the plasma autoantibody titre against ox‐LDL, a marker of in vivo oxidation, were determined. Results The ESR1 genotype persisted as the only significant predictor of adenosine stimulated coronary flow (P = 0·035) after adjustment for other coronary risk factors. Subjects with P/P genotype had 33·4 and 41·8% lower adenosine‐stimulated flow values than subjects with P/p and p/p genotypes (P = 0·030). Furthermore, plasma levels of ox‐LDL titre were on average 59 and 77% higher in subjects with P/P genotype than in subjects with P/p or p/p genotypes (P = 0·049). Conclusions These tentative findings from our pilot study provide evidence that genetic variation in ESR1 may modify coronary reactivity and LDL oxidation and reflect differences in the early pathogenesis of coronary dysfunction in these healthy young men.

Estrogen receptors (ESR) 1 and 2 are expressed in the normal and atherosclerotic arteries mediating the atheroprotective action of estrogen to artery wall cells. Whether variants of these receptor genes associate with autopsy-verified coronary artery wall atherosclerosis is not known. This study investigated whether variants of the ESR1 gene are associated with autopsy-verified coronary artery wall atherosclerosis and thrombosis. Coronary arteries were taken from 300 white Finnish male autopsy cases aged 33–69 years included in the Helsinki Sudden Death Study. Areas of coronary wall covered with fatty streaks, fibrotic, calcified, and complicated lesions were measured using computer-assisted planimetry and related to ESR1 PvuII genotypes (P/P, P/p, and p/p) determined by PCR. The mean area of complicated lesions of three major coronaries and the presence of coronary thrombosis were significantly associated with the ESR1 genotype in men aged 53 years or older (median age as a cut off point). No such association was found in men aged under 53 years. After adjusting for age and body mass index the men aged 53 years or over with P/p and P/P genotype had areas of complicated lesions on average two- and fivefold larger than subjects with the p/p genotype. The age and body mass index adjusted odds ratios for coronary thrombosis were 6.2 for P/p and 10.6 for P/P compared to men with the p/p genotype. After additional adjustment for diabetes and hypertension the ESR1 genotype persisted as an independent predictor of complicated lesions (P=0.007) and coronary thrombosis. In conclusion, the ESR1 gene is a potential candidate behind the pathogenesis of acute coronary events.

Background Impaired coronary flow reserve (CFR) can be used to indicate vascular dysfunction before the appearance of angiographic lesions. The hepatic lipase (HL) gene has a functional promoter polymorphism at position C‐480T, which affects transcription and leads to high activity (C/C) and low activity (C/T, T/T) genotypes. These genotypes modulate HL activity, but their role in coronary artery disease is controversial and the effect on coronary function has not been studied. We investigated whether HL genotypes are associated with coronary artery function in healthy young men.Materials and methods We studied 49 healthy, mildly hypercholesterolemic men (aged 35 ± 4 years). Myocardial blood flow was measured at rest and during adenosine induced hyperaemia with positron emission tomography using [¹⁵O] H₂O. HL genotype was determined by PCR and Nla III enzyme digestion.Results Resting myocardial blood flow was not statistically different in subjects with high and low activity HL genotypes. However, CFR (the ratio of adenosine flow to resting flow) was 24% higher (4·62 ± 1·52 vs. 3·73 ± 1·08 mL g⁻¹ min⁻¹, P = 0·024) in men with the high activity genotype (n = 26) than in those with low activity (n = 23). In multivariate analysis, the HL genotype remained a significant predictor of CFR (P = 0·038) after adjusting for age, body mass index, serum lipids and smoking.Conclusions The findings of our preliminary study suggest that the C‐480T polymorphism of the HL gene may modify coronary reactivity and reflect differences in the early pathogenesis of coronary dysfunction in these healthy young men. If the association between HL polymorphism and impaired CFR is also present in subjects with other dyslipoproteinemias, the HL polymorphism could be a new risk factor for cardiovascular disease.

The traditional method for DNA separation is slab gel electrophoresis. Because slab gel electrophoresis, which involves the casting, loading, running, and staining of the gel is labor-intensive and time-consuming, high-resolution capillary electrophoresis (CE) has become an attractive alternative. CE, by contrast to conventional electrophoretic techniques, is capable of rapid, automated, reproducible, and high-resolution separation of minute amounts of DNA samples. To separate DNA fragments by CE, polyacrylamide gels or liquid buffers containing soluble polymers are used. Soluble polymers, such as hydroxyethyl cellulose, hydroxypropylmethyl cellulose, and methyl cellulose act as effective molecular sieves and allow for separation of DNA according to size ( 1). CE has recently shown promising results for the analysis of double-stranded DNA such as restriction fragment length polymorphisms and polymerase chain reaction (PCR) products ( 2)( 3).

The effect of 1 wk of supervised fasting on plasma lipid concentrations in subjects with different apolipoprotein E (apo E) phenotypes was studied in 58 healthy free-living volunteers. The participants consumed an 870-kJ(208 kcal)/d liquid diet containing fruit and berry juices, tea, and water. The decline in plasma total cholesterol during 1 wk of fasting was 0.46 mmol/L in women and 0.35 mmol/L in men. The decreases were significant in both women and men. The response patterns of plasma total cholesterol were not significantly different between the sexes. In men, the changes in plasma low-density-lipoprotein cholesterol during the fast differed significantly (P = 0.0181) between the apo E phenotypes, whereas in women there were no differences due to phenotype (P = 0.695). The magnitude of the change in plasma triacylglycerol during the fast was different between the sexes (P = 0.0099). The changes in plasma triacylglycerols differed significantly between apo E phenotype groups in men (P = 0.0295) but not in women (P = 0.0661). Statistical comparison between different apo E phenotypes was performed with and without the small apo E3,2+E2,2 group, with essentially similar results. During fasting, plasma high-density-lipoprotein cholesterol concentrations decreased slightly but not significantly. The study shows significant differences in the associations of apo E alleles and sex on plasma lipid responses during fasting and illustrates the importance of gene-diet interactions in the regulation of lipid metabolism in humans.