A case-control study of lipoprotein particles in two populations at contrasting risk for coronary heart disease. The ECTIM Study

APO A2 -265T/C Polymorphism Is Associated with Increased Inflammatory Responses in Patients with Type 2 Diabetes Mellitus

BACKGROUND

Apolipoprotein A2 (APO A2) is the second most abundant structural apolipoprotein in high density lipoprotein. Several studies have examined the possible effect of APO A2 on atherosclerosis incidence. Due to the role of inflammation in atherosclerosis, we aimed to determine the relationship between APO A2 -265T/C polymorphism and inflammation as a risk factor in type 2 diabetes mellitus (T2DM) patients.

METHODS

In total, 180 T2DM patients, with known APO A2 -265T/C polymorphism, were recruited for this comparative study and were grouped equally based on their genotypes. Dietary intakes, anthropometric parameters, lipid profile, and inflammatory markers (i.e., pentraxin 3 [PTX3], high-sensitivity C-reactive protein [hs-CRP], and interleukin 18) were measured. The data were analyzed using an independent t-test, a chi-square test, and the analysis of covariance.

RESULTS

After adjusting for confounding factors, in the entire study population and in the patients with or without obesity, the patients with the CC genotype showed higher hs-CRP (P=0.001, P=0.008, and P=0.01, respectively) and lower PTX3 (P=0.01, P=0.03, and P=0.04, respectively) in comparison with the T allele carriers. In the patients with the CC genotype, no significant differences were observed in the inflammatory markers between the obese or non-obese patients. However, regarding the T allele carriers, the plasma hs-CRP level was significantly higher in the obese patients compared to the non-obese patients (P=0.01).

CONCLUSION

In the T2DM patients, the CC genotype could be considered as a risk factor and the T allele as a protective agent against inflammation, which the latter effect might be impaired by obesity. Our results confirmed the anti-atherogenic effect of APO A2, though more studies are required to establish this effect.

Association between ApoA-II -265T/C polymorphism and oxidative stress in patients with type 2 diabetes mellitus

BACKGROUND

Apolipoprotein A-II (ApoA-II) constitutes approximately 20% of the total HDL protein content. The results of various studies on the relationship between cardiovascular diseases (CVD) and the plasma ApoA-II level are contradictory. The aim of this study was to determine the relationship between ApoA-II polymorphism and oxidative stress (OS) as a risk factor for CVD.

METHODS

The present comparative study was carried out on 180 obese and non-obese patients with type 2 diabetes, with equal numbers of CC, TC, and TT genotypes of ApoA-II -265T/C gene. The ApoA-II genotype was determined by the TaqMan assay method. The anthropometric measurements and serum levels of lipid profile, superoxide dismutase activity (SOD), total antioxidant capacity (TAC), and 8-isoprostaneF2α were measured.

RESULTS

After adjusting for confounding factors, in the total study population and in obese and non-obese groups, the subjects with CC genotype had a lower mean serum SOD activity (p=0.002, p=0.007 and p=0.005, respectively) and higher mean 8-isoprostaneF2α concentration (p<0.001, p=0.003 and p=0.004, respectively) than the T-allele carriers. In the TT/TC group, the mean 8-isoprostanF2α concentration was significantly higher in the obese subjects than the non-obese subjects (p=0.009). In the CC group, no significant differences were found in the OS factors between obese and non-obese groups.

CONCLUSION

The T allele in patients with type 2 diabetes is a protective factor against OS; obesity inhibits this protective effect. The results of this study represent the anti-atherogenic properties of ApoA-II. However, further studies are needed in this field.

The Coronary Artery Disease and Renal Failure (CAD-REF) registry: trial design, methods, and aims

BACKGROUND

During the past 10 years, chronic kidney disease (CKD) has been recognized as a major global health problem. Factors leading to decreased renal function are closely related to cardiovascular disease and vice versa. Cardiovascular morbidity and mortality are substantially increased in patients with CKD, even in those with only mild or moderate renal impairment. A better understanding of pathogenesis, risk factors, and genetic conditions is strongly required for more specific treatment strategies in CKD because until now, knowledge is very limited.

METHODS

The German CAD-REF registry is a prospective observational multicenter national registry. It aims at including >3,300 white patients with angiographically documented coronary artery disease (coronary artery disease [CAD]; ≥50% stenosis in at least 1 coronary artery) being enrolled at 32 centers and assigned to 6 different groups according to their estimated glomerular filtration rate and/or proteinuria. Baseline characteristics, treatment data, and biomaterial including serum, plasma, urine, and DNA samples are collected. Follow-ups are performed at 6, 12, 24, 36, 48, and 60 months.

CONCLUSIONS

The CAD-REF registry will establish one of the largest ethnically homogeneous cohorts, to date, of clinically and angiographically well-characterized patients with CAD who have all stages of CKD. This approach offers great opportunities for an improved understanding of the underlying pathophysiologic mechanism and clinical impact of CKD in patients with CAD, especially including the identification of clinically relevant risk factors and (genetic and other bio-) markers as a basis to ameliorate future treatment strategies.

A study on the polymorphisms of the renin-angiotensin system pathway genes for their effect on blood pressure levels in males from Algeria

INTRODUCTION

Several studies have assessed the relationship between blood pressure (BP) and polymorphisms within the genes encoding angiotensinogen (AGT), angiotensin II type 1 receptor (AT1R) and angiotensin-converting enzyme (ACE). However, considering the relatively large discrepancy in frequency and impact of these variants between ethnic groups and populations, still unavailable data from Algerian population are needed.

OBJECTIVE

Our purpose is to evaluate the association between the AGT M235T, AT1R +1166A/C and ACE I/D polymorphisms and variations in systolic (SBP), diastolic (DBP) and pulse pressure (PP) values.

METHODS

The associations with BP were assessed in a representative sample of 115 male subjects free of coronary heart disease (CHD). The AGT M235T, AT1R +1166A/C and ACE I/D polymorphisms were determined by PCR-ASO and PCR-RFLP analysis, respectively.

RESULTS

We showed no associations between the AGT M235T, AT1R +1166A/C nor the ACE I/D polymorphisms with variations in BP values. However, concerning the ACE I/D polymorphism, subjects carrying the ACE I allele tended to have higher SBP (+4.1 mmHg) and PP values (+3.2 mmHg) than DD subjects (adjusted p = 0.087 and p = 0.102, respectively).

CONCLUSION

The ACE I/D polymorphism needs further investigation in a larger Algerian study, especially concerning its putative impact on SBP and PP.

Apolipoprotein A-II: evaluating its significance in dyslipidaemia, insulin resistance, and atherosclerosis

Reduced HDL cholesterol, commonly found in subjects with obesity and type 2 diabetes, is associated with increased risk of cardiovascular disease (CVD). ApoA-II, a constituent apolipoprotein of certain HDL particles, plays an important role in the regulation of cholesterol efflux, HDL remodelling, and cholesteryl ester uptake via its interactions with lipid transfer proteins, lipases, and cellular HDL receptors. Recent studies have linked apoA-II directly with triglyceride and glucose metabolism. Most of the data are, however, derived from cellular systems and transgenic animal models. Direct evidence from human studies is scarce. Clinical studies demonstrate that apoA-II is a strong predictor of risk for CVD. There is no evidence, however, that selective therapeutic modification of apoA-II impacts on atherosclerosis and clinical outcomes. More research is required to investigate further the significance of apoA-II in clinical medicine.

The Association between Apolipoprotein A-II and Metabolic Syndrome in Korean Adults: A Comparison Study of Apolipoprotein A-I and Apolipoprotein B

BACKGROUND

Apolipoprotein A-II (apoA-II) is the second-most abundant apolipoprotein in human high-density lipoprotein and its role in cardio metabolic risk is not entirely clear. It has been suggested to have poor anti-atherogenic or even pro-atherogenic properties, but there are few studies on the possible role of apoA-II in Asian populations. The aim of this study is to evaluate the role of apoA-II in metabolic syndrome (MetS) compared with apolipoprotein A-I (apoA-I) and apolipoprotein B (apoB) in Korean adults.

METHODS

We analyzed data from 244 adults who visited the Center for Health Promotion in Pusan National University Yangsan Hospital for routine health examinations.

RESULTS

The mean apoB level was significantly higher, and the mean apoA-I level was significantly lower, in MetS; however, there was no significant difference in apoA-II levels (30.5±4.6 mg/dL vs. 31.2±4.6 mg/dL, P=0.261). ApoA-II levels were more positively correlated with apoA-I levels than apoB levels. ApoA-II levels were less negatively correlated with homocysteine and high sensitivity C-reactive protein levels than apoA-I levels. The differences in MetS prevalence from the lowest to highest quartile of apoA-II were not significant (9.0%, 5.7%, 4.9%, and 6.6%, P=0.279). The relative risk of the highest quartile of apoA-II compared with the lowest quartile also was not significantly different (odds ratio, 0.96; 95% confidence interval, 0.95 to 1.04; P=0.956).

CONCLUSION

Compared with apoA-I (negative association with MetS) and apoB (positive association with MetS) levels, apoA-II levels did not show any association with MetS in this study involving Korean adults. However, apoA-II may have both anti-atherogenic and pro-atherogenic properties.

Biological activities of HDL subpopulations and their relevance to cardiovascular disease

The concept of raising high-density lipoprotein (HDL) has been the focus of increasing attention as a strategy to reduce cardiovascular disease. HDL particles are, however, highly heterogeneous in structure, intravascular metabolism and biological activity. In this review, we describe major HDL subpopulations and discuss new findings on the antiatherogenic properties of HDL particles. Across the HDL subpopulation spectrum, small, dense, protein-rich HDLs display potent atheroprotective properties, which can be attributed to specific clusters of proteins and lipids; such activities can be compromised under conditions of atherogenic dyslipidemia. Comprehensive structural and compositional analyses of HDL may provide key information to identify subpopulations displaying specific biological functions and acquiring deficient functionality, with the potential to reveal novel biomarkers of cardiovascular risk and new pharmacological targets.

A genome-wide association study identifies two loci associated with heart failure due to dilated cardiomyopathy

AIMS

Dilated cardiomyopathy (DCM) is a major cause of heart failure with a high familial recurrence risk. So far, the genetics of DCM remains largely unresolved. We conducted the first genome-wide association study (GWAS) to identify loci contributing to sporadic DCM.

METHODS AND RESULTS

One thousand one hundred and seventy-nine DCM patients and 1108 controls contributed to the discovery phase. Pools of DNA stratified on disease status, population, age, and gender were constituted and used for testing association of DCM with 517 382 single nucleotide polymorphisms (SNPs). Three DCM-associated SNPs were confirmed by individual genotyping (P < 5.0 10(-7)), and two of them, rs10927875 and rs2234962, were replicated in independent samples (1165 DCM patients and 1302 controls), with P-values of 0.002 and 0.009, respectively. rs10927875 maps to a region on chromosome 1p36.13 which encompasses several genes among which HSPB7 has been formerly suggested to be implicated in DCM. The second identified locus involves rs2234962, a non-synonymous SNP (c.T757C, p. C151R) located within the sequence of BAG3 on chromosome 10q26. To assess whether coding mutations of BAG3 might cause monogenic forms of the disease, we sequenced BAG3 exons in 168 independent index cases diagnosed with familial DCM and identified four truncating and two missense mutations. Each mutation was heterozygous, present in all genotyped relatives affected by the disease and absent in a control group of 347 healthy individuals, strongly suggesting that these mutations are causing the disease.

CONCLUSION

This GWAS identified two loci involved in sporadic DCM, one of them probably implicates BAG3. Our results show that rare mutations in BAG3 contribute to monogenic forms of the disease, while common variant(s) in the same gene are implicated in sporadic DCM.

HDL Measures, Particle Heterogeneity, Proposed Nomenclature, and Relation to Atherosclerotic Cardiovascular Events

BACKGROUND

A growing body of evidence from epidemiological data, animal studies, and clinical trials supports HDL as the next target to reduce residual cardiovascular risk in statin-treated, high-risk patients. For more than 3 decades, HDL cholesterol has been employed as the principal clinical measure of HDL and cardiovascular risk associated with low HDL-cholesterol concentrations. The physicochemical and functional heterogeneity of HDL present important challenges to investigators in the cardiovascular field who are seeking to identify more effective laboratory and clinical methods to develop a measurement method to quantify HDL that has predictive value in assessing cardiovascular risk.

CONTENT

In this report, we critically evaluate the diverse physical and chemical methods that have been employed to characterize plasma HDL. To facilitate future characterization of HDL subfractions, we propose the development of a new nomenclature based on physical properties for the subfractions of HDL that includes very large HDL particles (VL-HDL), large HDL particles (L-HDL), medium HDL particles (M-HDL), small HDL particles (S-HDL), and very-small HDL particles (VS-HDL). This nomenclature also includes an entry for the pre-β-1 HDL subclass that participates in macrophage cholesterol efflux.

SUMMARY

We anticipate that adoption of a uniform nomenclature system for HDL subfractions that integrates terminology from several methods will enhance our ability not only to compare findings with different approaches for HDL fractionation, but also to assess the clinical effects of different agents that modulate HDL particle structure, metabolism, and function, and in turn, cardiovascular risk prediction within these HDL subfractions.

ABCA1 gene variants regulate postprandial lipid metabolism in healthy men

OBJECTIVE

Genetic variants of ABCA1, an ATP-binding cassette (ABC) transporter, have been linked to altered atherosclerosis progression and fasting lipid concentration, mainly high-density lipoproteins and apolipoprotein A1; however, results from different studies have been inconsistent.

METHODS AND RESULTS

To further characterize the effects of ABCA1 variants in human postprandial lipid metabolism, we studied the influence of 3 single nucleotide polymorphisms (i27943 [rs2575875]; i48168 [rs4149272]; R219K [rs2230806]) in the postprandial lipemia of 88 normolipidemic young men who were given a fatty meal. For i27943 and i48168 single nucleotide polymorphisms, fasting and postprandial values of apolipoprotein A1 were higher and postprandial lipemia was much lower in homozygotes for the major alleles, total triglycerides in plasma, and large triglyceride-rich lipoprotein triglycerides. These persons also showed a higher apolipoprotein A1/apolipoprotein B ratio. Major allele homozygotes for i48168 and i27943 showed additionally higher high-density lipoproteins and lower postprandial apolipoprotein B.

CONCLUSION

Our work shows that major allele homozygotes for ABCA1 single nucleotide polymorphisms i27943 and i48168 have a lower postprandial response as compared to minor allele carriers. This finding may further characterize the role of ABCA1 in lipid metabolism.

Cholesterol metabolism and transport in the pathogenesis of Alzheimer's disease

Alzheimer's disease (AD) is the most common neurodegenerative disorder, affecting millions of people worldwide. Apart from age, the major risk factor identified so far for the sporadic form of AD is possession of the epsilon4 allele of apolipoprotein E (APOE), which is also a risk factor for coronary artery disease (CAD). Other apolipoproteins known to play an important role in CAD such as apolipoprotein B are now gaining attention for their role in AD as well. AD and CAD share other risk factors, such as altered cholesterol levels, particularly high levels of low density lipoproteins together with low levels of high density lipoproteins. Statins--drugs that have been used to lower cholesterol levels in CAD, have been shown to protect against AD, although the protective mechanism(s) involved are still under debate. Enzymatic production of the beta amyloid peptide, the peptide thought to play a major role in AD pathogenesis, is affected by membrane cholesterol levels. In addition, polymorphisms in several proteins and enzymes involved in cholesterol and lipoprotein transport and metabolism have been linked to risk of AD. Taken together, these findings provide strong evidence that changes in cholesterol metabolism are intimately involved in AD pathogenic processes. This paper reviews cholesterol metabolism and transport, as well as those aspects of cholesterol metabolism that have been linked with AD.

Determinants of risk factors of atherosclerosis in the postinfarction period: The Tallinn MI Study

Environmental as well as genetic factors are involved in the pathogenesis of myocardial infarction. The disease is a frequent cause of mortality in the middle-aged male population of Estonia. The high prevalence of premature myocardial infarction (PMI) in this country is not fully understood. The association of atherogenic and thrombogenetic risk factors with lifestyle was evaluated in men who had suffered myocardial infarction at 55 years of age (n = 71) and in randomly selected corresponding controls (n = 85). Serum routine lipids, apolipoprotein (apo)A-I, apoB, apoE polymorphism, lipoprotein(a) and fibrinogen levels were determined. Behavioural risk factors, indices of obesity, blood pressure and pedigree data were registered. In 80.6 % of PMI subjects some type of hyperlipidaemia was observed (European Atherosclerosis Society Classification) and lipid-lowering drugs were taken by 13.9 % of patients. In PMI patients the most common positive determinants of atherogenic lipoprotein indices were waist-to-hip ratio and physical inactivity, and in controls, waist-to-hip ratio and apoE phenotype. The odds ratio (OR) of PMI was 8.9-fold greater in the highest tertile of apoB/apoA-I distribution compared with the lowest tertile. The OR of PMI in the highest tertile of fibrinogen distribution versus the lowest tertile was 6.2 (95 % CI 2.46-15.44), and OR of PMI in the highest Lp(a) tertile versus the lowest was 3.1 (95 % CI 1.31-7.40). Thus, atherogenic dyslipidaemia was the most serious cardiovascular risk factor among PMI patients. From two thrombogenesis-related markers, the levels of fibrinogen and Lp(a), the first one was more strongly associated with PMI status.

Molecular and functional characterization of polymorphisms in the secreted phospholipase A2 group X gene: relevance to coronary artery disease

Among secreted phospholipases A2 (sPLA2s), human group X sPLA2 (hGX sPLA2) is emerging as a novel attractive therapeutic target due to its implication in inflammatory diseases. To elucidate whether hGX sPLA2 plays a causative role in coronary artery disease (CAD), we screened the human PLA2G10 gene to identify polymorphisms and possible associations with CAD end-points in a prospective study, AtheroGene. We identified eight polymorphisms, among which, one non-synonymous polymorphism R38C in the propeptide region of the sPLA2. The T-512C polymorphism located in the 5' untranslated region was associated with a decreased risk of recurrent cardiovascular events during follow-up. The functional analysis of the R38C polymorphism showed that it leads to a profound change in expression and activity of hGX sPLA2, although there was no detectable impact on CAD risk. Due to the potential role of hGX sPLA2 in inflammatory processes, these polymorphisms should be investigated in other inflammatory diseases.

Angiotensin I-converting enzyme I/D polymorphism and suicidal behaviors

Suicide is one of the ten most common causes of death in Western countries. It involves genetic vulnerability factors and is often associated with major depression. A Japanese team reported an association between the insertion allele of the angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism with completed suicide. The ACE I/D polymorphism was investigated in two independent case-control studies, one involving 64 suicide completers and 90 controls who all underwent forensic investigations, the second one consisting of 588 suicide attempters and 639 controls. In the two population samples studied a statistically significant risk of suicidal behavior was observed for subjects bearing the DD genotype. These results suggest a possible role of the renin-angiotensin system in suicidal behavior.

Genome-wide haplotype association study identifies the SLC22A3-LPAL2-LPA gene cluster as a risk locus for coronary artery disease

We identify the SLC22A3-LPAL2-LPA gene cluster as a strong susceptibility locus for coronary artery disease (CAD) through a genome-wide haplotype association (GWHA) study. This locus was not identified from previous genome-wide association (GWA) studies focused on univariate analyses of SNPs. The proposed approach may have wide utility for analyzing GWA data for other complex traits.

Effect of ABCA1 mutations on risk for myocardial infarction

The adenosine triphosphate-binding cassette A1 (ABCA1) gene codes for a cellular phospholipid and cholesterol transporter that mediates the initial and essential step in high-density lipoprotein (HDL) biogenesis: the formation of nascent HDL particles. Mutations at the ABCA1 gene locus cause severe familial HDL deficiency and, in the homozygous form, cause Tangier disease. Several studies have investigated the influence of ABCA1 variation on lipid metabolism and coronary heart disease, but they have resulted in controversial and inconsistent results. Genetic variability at the ABCA1 gene has also been associated with increased risk of myocardial infarction. In one study, this association was independent of HDL cholesterol levels, raising the possibility that the measurement of HDL cholesterol levels may not provide adequate information on the functional roles of HDL particles. Nevertheless, genomic screening for complex diseases, such as coronary heart disease, and HDL deficiency in particular, may not add additional information to that gained from conventional global cardiovascular risk stratification.

Laboratory assessment of HDL heterogeneity and function

BACKGROUND

Plasma concentrations of HDL cholesterol (HDL-C) and its major protein component apolipoprotein (apo) A-I are strongly inversely associated with cardiovascular risk, leading to the concept that therapy to increase HDL-C and apoA-I concentrations would be antiatherosclerotic and protective against cardiovascular events. The recent failure of the drug torcetrapib, a cholesteryl ester transfer protein inhibitor that substantially increased HDL-C concentrations, has brought focus on the issues of HDL heterogeneity and function as distinct from HDL-C concentrations.

CONTENT

This review addresses the current state of knowledge regarding assays of HDL heterogeneity and function and their relationship to cardiovascular disease. HDL is highly heterogeneous, with subfractions that can be identified on the basis of density, size, charge, and protein composition, and the concept that certain subfractions of HDL may be better predictors of cardiovascular risk is attractive. In addition, HDL has been shown to have a variety of functions that may contribute to its cardiovascular protective effects, including promotion of macrophage cholesterol efflux and reverse cholesterol transport and antiinflammatory and nitric oxide-promoting effects.

SUMMARY

Robust laboratory assays of HDL subfractions and functions and validation of the usefulness of these assays for predicting cardiovascular risk and assessing response to therapeutic interventions are critically important and of great interest to cardiovascular clinicians and investigators and clinical chemists.

The apolipoprotein AII rs5082 variant is associated with reduced risk of coronary artery disease in an Australian male population

Serum high density lipoprotein (HDL) levels are inversely related to the development of coronary artery disease (CAD). Apolipoproteins AI and AII are the major protein constituents of HDL particles. APOAI and APOAII genetic polymorphisms have been proposed to affect transcriptional efficiency of their respective genes, thereby altering serum lipid levels and influencing atherosclerotic disease risk. 556 subjects with angiographically proven CAD (>50% stenosis) and 1109 randomly selected individuals from metropolitan Perth, Western Australia, were included in an association study. APOAI -75G/A (rs670) and APOAII -256T/C (rs5082) polymorphisms were both found to be not associated with plasma HDL levels. In a case-control analysis of 484 male CAD patients and 498 male controls, individuals carrying the 'CC' genotype for the APOAII rs5082 polymorphism had significantly lower risk of CAD than the 'T' allele carriers (OR=0.57, 95% CI 0.39-0.84, p=0.004). The minor 'A' allele of the APOAI rs670 polymorphism was found to be not associated with CAD, contrary to previous reports. We conclude that the APOAII rs5082 polymorphism appears to be cardioprotective in this representative Caucasian Australian population.

An apolipoprotein A-II polymorphism (-265T/C, rs5082) regulates postprandial response to a saturated fat overload in healthy men

Apolipoprotein (Apo) A-II is an apolipoprotein with an unknown role in lipid metabolism. It has been suggested that the presence of the less frequent allele of a single nucleotide polymorphism (Apo A-II -265T/C, rs5082) reduces the transcription rate of Apo A-II and enhances VLDL postprandial clearance in middle-aged men. To further investigate the role of Apo A-II -265T/C on lipid metabolism, we studied 88 normolipidemic young men. The participants were given a fatty meal containing 1 g fat and 7 mg cholesterol/kg weight and capsules containing 60,000 IU vitamin A (retinyl palmitate, 15.15 mg RE) per square meter body surface area. Postprandial lipemia was assessed during the 11 h following the meal. Total cholesterol (Chol) and triacylglycerols (TG) in plasma and TG-rich lipoproteins (TRL) (large TRL and small TRL) were measured, as well as HDL, Apo A-I, Apo B, Apo B-48, and Apo B-100. Postprandial responses were higher in the TT group than in carriers of the minor allele (CC/TC) for total TG in plasma (21.37% of change of area under curve, P = 0.014), large TRL-TG (24.75% change, P = 0.017) and small TRL-Chol (26.63% change, P = 0.003). Our work shows that carriers of the minor allele for Apo A-II -265T/C (CC/TC) have a lower postprandial response compared with TT homozygotes. This finding may partially explain the role of Apo A-II in lipid metabolism and can identify a population with a decreased risk of cardiovascular disease, as corresponds to the lower level of postprandial hypertriglyceridemia.

Polymorphisms in 33 inflammatory genes and risk of myocardial infarction--a system genetics approach

The hypothesis of a causal link between inflammation and atherosclerosis would be strengthened if variants of inflammatory genes were associated with disease. Polymorphisms of 33 genes encoding inflammatory molecules were tested for association with myocardial infarction (MI). Patients with MI and a parental history of MI (n = 312) and controls from the UK (n = 317) were genotyped for 162 polymorphisms. Thirteen polymorphisms were associated with MI (P values ranging from 0.003 to 0.041). For three genes, ITGB1, SELP, and TNFRSF1B haplotype frequencies differed between patients and controls (P values < 0.01). We further assessed the simultaneous contribution of all polymorphisms and relevant covariates to MI using a two-step strategy of data mining relying on Random Forest and DICE algorithms. In a replication study involving two independent samples from the UK (n = 649) and France (n = 706), one interaction between the ITGA4/R898Q polymorphism and current smoking status was replicated. This study illustrates a strategy for assessing the joint effect of a large number of polymorphisms on a phenotype that may provide information that single locus or single gene analysis may fail to uncover. Overall, there was weak evidence for an implication of inflammatory polymorphisms on susceptibility to MI.

Neutrophil elastase gene variation and coronary heart disease

AIMS

Identification and functional characterization of variants in the neutrophil elastase (ELA2) gene in cardiovascular disease.

METHODS

From participants of the ECTIM (Etude Cas-Témoins sur l'infarctus du Myocarde) Study with myocardial infarction (MI) 2082 chromosomes were genetically scanned; 990 patients with MI and 904 controls were genotyped for the common polymorphisms G-761A and S173S (C4890A). Expression vectors for Ela2 variants were transiently transfected, followed by Northern and Western blot analyses. Promoter variants were analyzed by transfection/reporter gene assays.

RESULTS

We identified 11 genetic variants, two in the 5'-flanking (G-761A, -852/del53 bp), six in exons (R49H, N81N, G93V, S173S, D222Y, P228L) and three in introns (C+29/in3T, C+149/in3T, C+137/in4T). In Belfast, 4890A allele carriers had a risk for MI with an odds ratio (OR) of 1.44 (95% CI 1.12-1.86; P=0.005), the OR for MI associated with the -761G/-4890A haplotype with reference to -761G/-4890C amounting to 2.38 (95% CI 1.23-4.57; P=0.01). Transcript or protein expression of both allelic constructs (4890A and 4890C) did not, however, differ. Conversely, transcriptional activity was significantly elevated (<35%) by -852/del53 bp in THP-1 monocytes compared with the nondeleted promoter (P=0.001); the deletion was observed in one patient with premature MI at the age of 28 years, whose mother had had an MI at the age of 48 years.

CONCLUSIONS

The association of C4890A with MI in Belfast exclusively, and the presumed absence of its functionality, provides little support for a substantial implication of common ELA2 gene variants in overall MI risk. Whether -852/53del plays a role in cardiovascular pathophysiology or not should be evaluated further.

Differential haplotypic expression of the interleukin-18 gene

Interleukin 18 (IL-18) is suspected to play an important role in atherosclerosis and plaque vulnerability. We had previously shown that haplotypes combining two IL18 gene polymorphisms in complete linkage disequilibrium, C-105T (rs360717) in 5'-untranslated region (UTR) and A+183G (rs5744292) in 3'-UTR, were related to IL-18 circulating levels and cardiovascular outcome, the C(-105) G(+183) haplotype being associated with lower IL-18 levels and lower cardiovascular risk. This study was aimed at investigating the functional role of the two polymorphisms and their haplotypes on IL18 expression levels. Allelic imbalance experiments conducted in 24 and 20 subjects heterozygous for the C-105T and the A+183G polymorphisms did not detect any difference when subjects were considered as a whole (-0.009+/-0.044, P=0.85 and +0.114+/-0.082, P=0.18, respectively). However, when splitting individuals according to their haplo-genotype, the haplotype C(-105) G(+183) was associated with a lower expression level than C(-105) A(+183) (-0.287+/-0.076, P=0.005), but did not differ from T(-105) A(+183) (-0.138+/-0.083, P=0.13). The lower expression associated with C(-105) G(+183) was confirmed by real-time reverse transcription-PCR. Transfection of different haplotypic versions of the 3'-UTR did not show any difference in the expression of an upstream reporter gene. A 10-h study of the mRNA degradation kinetics by allelic imbalance with the A+183G polymorphism did not show any differential allelic degradation. In conclusion, the haplotype associated with lower IL-18 circulating concentrations and a lower cardiovascular risk was consistently associated with decreased IL18 expression levels, although the exact functional mechanisms remain to be elucidated.

Lack of association between complement factor H polymorphisms and coronary artery disease or myocardial infarction

Complement factor H (CFH) plays a critical role in the protection of host cells and tissues from damage by complement activation and has been suggested to protect against the progression of atherosclerosis. A polymorphism in the CFH gene, Y402H, known to be strongly associated with age-related macular degeneration, has been analyzed in relation to coronary artery disease (CAD) in several studies with conflicting results. We investigated the association of polymorphisms of the CFH gene in two large-scale studies on CAD and myocardial infarction (MI). The AtheroGene Study included a cohort of cases with CAD (n = 1,303) prospectively followed for a median period of 6.2 years, among whom198 experienced a cardiovascular event, and a group of 483 control subjects. The AtheroGene Study population was genotyped for the Y402H, I62V, and E936D polymorphisms. There was no significant difference in genotypic or allelic frequencies between CAD cases and controls. Among cases, no significant association was found with prospective cardiovascular outcome. Many inflammatory proteins, including the C-reactive protein, were measured, and none of the polymorphisms showed an association with these markers. The Etude Cas-Témoin de l'Infarctus du Myocarde (ECTIM) Study compared 1,034 patients with MI and 1,039 controls from France and United Kingdom. The ECTIM Study population was genotyped for the Y402H polymorphism. Genotype and allele frequencies were similar in cases and controls. These results do not support an involvement of common nonsynonymous polymorphisms of the CFH gene in predisposition to CAD and its complications.

High-density lipoprotein associations with coronary heart disease: Does measurement of cholesterol content give the best result?

The protective role played by high-density lipoprotein (HDL) in atherogenesis is well-accepted, as is the significant inverse association of HDL cholesterol (HDL-C) with coronary heart disease (CHD) risk. What remains controversial is whether we are using the best measure(s) of HDL to identify and manage HDL-related cardiovascular risk. Measuring particle number has been postulated to offer additional and possibly more specific information regarding risk. Although HDL-C is thought to indicate the quantity of circulating HDL particles, it is underappreciated that the amount of cholesterol carried inside lipoprotein particles is highly variable among individuals with the same HDL-C. Numerous trials have investigated the relations of CHD with various measures of HDL other than those based on cholesterol content of the particles present. Studies regarding the association of alternate measures of HDL with CHD risk have been mixed, possibly due to diversity in clinical characteristics accompanying low HDL-C states, variability in cholesterol content of HDL particles, and substantial inter-correlations of HDL with other lipoprotein particles. Additional research is needed to assess the clinical settings in which individual HDL tests, after multivariate adjustment for confounding factors, provide superior independent prediction of CHD events beyond HDL-C. Such studies show promise in defining measures of particle number that will prove useful in future strategies to enhance management of CHD risk and assess response to therapy at an individual patient level.

Reference distributions for apolipoproteins AI and B and B/AI ratios: comparison of a large cohort to the world's literature

Limiting the clinical utility of apolipoproteins AI (apo AI) and B (apo B) and the apo B/AI ratios until the last decade has been the lack of satisfactory methods for quantifying serum levels and credible reference materials. Great technological strides have been made in the last few years. The remaining barrier to more relevant and cost-effective use of serum protein data for diagnosis and prognosis has been the availability of widely recognized reliable reference intervals from birth to old age for both males and females. A total of 82 publications reporting reference intervals have been identified that meet most of the same inclusion criteria used in our prior six studies. These have been analyzed statistically and compared to similar studies, i.e., sufficient number, listed subject criteria, method, and reference material, in general terms. Published smaller studies with constrained age ranges, agree on average with our large series of life-long reference intervals that range from less than one year to over 80 years. This study was performed to assess the degree of agreement between smaller reference interval studies to our large population analysis. This meta-analysis provides support and reassurance that many of the smaller reference intervals published previously fall within reasonable limits of out large population.

Polyacrylamide gradient gel electrophoresis of lipoprotein subclasses

High-density (HDL), low-density (LDL), and very-low-density (VLDL) lipoproteins are heterogeneous cholesterol-containing particles that differ in their metabolism, environmental interactions, and association with disease. Several protocols use polyacrylamide gradient gel electrophoresis (GGE) to separate these major lipoproteins into known subclasses. This article provides a brief history of the discovery of lipoprotein heterogeneity and an overview of relevant lipoprotein metabolism, highlighting the importance of the subclasses in the context of their metabolic origins, fates, and clinical implications. Various techniques using polyacrylamide GGE to assess HDL and LDL heterogeneity are described, and how the genetic and environmental determinations of HDL and LDL affect lipoprotein size heterogeneity and the implications for cardiovascular disease are outlined.

LpA-I, LpA-I:A-II HDL and CHD-risk: The Framingham Offspring Study and the Veterans Affairs HDL Intervention Trial

OBJECTIVE

We tested the hypothesis that concentrations of LpA-I and/or LpA-I:A-II HDL subclasses are significantly associated with CHD prevalence and recurrent cardiovascular events.

METHODS

LpA-I levels were determined by differential electroimmunoassay in male participants with (n = 169) and without CHD (n = 850) from the Framingham Offspring Study (FOS) and in male participants with CHD from the placebo arm of the Veterans Affairs HDL Intervention Trial (VA-HIT) (n = 741). Data were analyzed cross-sectionally (FOS) and prospectively (VA-HIT) and were adjusted for established lipid and non-lipid CHD risk factors.

RESULTS

We observed slightly but significantly higher LpA-I levels in CHD cases compared to all or to HDL-C-matched controls and slightly but significantly higher LpA-I:A-II levels in CHD cases compared to HDL-C-matched controls it the FOS. Neither LpA-I nor LpA-I:A-II levels were significantly different between groups with and without recurrent cardiovascular events in the VA-HIT. No significant differences were observed in LpA-I and LpA-I:A-II levels in low HDL-C (< or = 40 mg/dl) subjects with CHD (VA-HIT, n = 711) and without CHD (FOS, n = 373). Plasma LpA-I concentration had a positive correlation with the large LpA-I HDL particle (alpha-1) but no correlation with the small LpA-I HDL particle (prebeta-1). LpA-I:A-II concentration had a positive correlation with the large (alpha-2) and an inverse correlation with the small (alpha-3) LpA-I:A-II HDL particles.

CONCLUSION

Our data do not support the hypothesis that CHD prevalence (FOS) or recurrence of cardiovascular events (VA-HIT) are associated with significant reductions in the concentrations of LpA-I and/or LpA-I:A-II HDL subclasses.

Angiographically confirmed coronary heart disease and periodontal disease in middle-aged males

BACKGROUND

The aim of this study was to investigate whether an association could be demonstrated between coronary heart disease (CHD) and chronic periodontitis in a population of middle-aged males in Northern Ireland.

METHODS

A case-control design was used. Cases were men aged over 40 years with angiographically proven CHD. Controls were age-matched males, with no evidence of CHD, randomly drawn from the same locality as the cases. Each subject had a clinical periodontal examination and completed a detailed sociodemographic questionnaire. High sensitivity C-reactive protein (CRP) was measured in serum by immunoturbidimetry.

RESULTS

There were 92 cases (mean age 56.7 years; SD = 6.3) and 79 controls (mean age 58.2 years; SD = 6.7). The CHD cases had an average of three teeth less than the controls (P <0.0001). A higher proportion of sites examined in cases than controls had plaque (P = 0.004), bleeding on probing (P = 0.013), and probing depths of > or = 4 mm (P = 0.006) or > or = 6 mm (P = 0.03). Subjects with > or = 4 mm pocketing in more than 20% of their interproximal sites and those with deep pocketing (> or = 6 mm) were classified as having poor periodontal status. A total of 35 cases (38%), compared to only 13 controls (16%), had a poor periodontal status (P = 0.0017). Men with a poor periodontal condition had higher levels of CRP (median 2.19 mg/l) than those with good periodontal health (median 1.42 mg/l), P = 0.007. After adjusting for smoking, academic achievement, alcohol consumption, unemployment, ability to maintain body weight, regular exercise, ability to relax daily, having a hobby or pastime, plaque, and CRP, logistic regression analysis showed that poor periodontal status was significantly associated with CHD, with an adjusted odds ratio of 3.06 and 95% confidence intervals of 1.02 to 9.17, P = 0.046.

CONCLUSIONS

There was an association between coronary heart disease and poor periodontal status in the middle-aged males investigated. This association was independent of diabetes and all other cardiovascular risk factors investigated.

Predictors of coronary artery disease in the Lebanese population

BACKGROUND

Coronary artery disease (CAD) is one of the major causes of morbidity and mortality in the world. The disease is determined by many risk factors such as age, gender, diabetes, dyslipidemia, smoking, as well as elevated serum levels of lipoprotein (a) (Lp(a)), homocysteine, C-reactive protein (CRP) and uric acid. In this study, we evaluated the association of biologic and metabolic parameters with CAD in a group of Lebanese patients.

METHODS

Three hundred patients were recruited for the study. Biologic and blood metabolic parameters were measured. Patients were then divided into 3 groups according to their catheterization result: 0% stenosis (controls), <50% stenosis and >or=50% stenosis.

RESULTS

Hyperlipidemias, CRP, homocysteine and uric acid levels in CAD patients were not different from those of the controls. However, age, elevated fasting blood glucose (FBG) and elevated serum Lp(a) levels were found to be strong independent predictors of CAD in our study population. Association with CAD was also shown for gender, hypertension, diabetes and family history of CAD.

CONCLUSION

We report the importance of serum Lp(a) levels and FBG in the prediction and prevention of CAD in our population.

Value of High-Density Lipoprotein (HDL) Subpopulations in Predicting Recurrent Cardiovascular Events in the Veterans Affairs HDL Intervention Trial

Objective— To test the hypothesis whether determination of high-density lipoprotein (HDL) subpopulations provides more power to predict recurrent cardiovascular disease (CVD) events (nonfatal myocardial infarction, coronary heart disease death, and stroke) than traditional risk factors in the Veterans Affairs HDL Intervention Trial (VA-HIT).

Methods and Results— Apolipoprotein A-I (apoA-I)–containing HDL subpopulations were quantitatively determined by nondenaturing 2D gel electrophoresis. Hazard ratios of recurrent CVD events were calculated by comparing VA-HIT subjects with (n=398) and without (n=1097) such events. Subjects with new CVD events had significantly lower HDL-C, apoA-I, and large cholesterol-rich HDL particle (α-1, α-2, pre–α-1, and pre–α-2) levels, significantly higher triglyceride, and small poorly lipidated HDL particle (pre–β-1 and α-3) levels than subjects without such events. Multivariate analyses indicated that α-1 and α-2 particle levels were significant negative risk factors, whereas α-3 level was a significant positive risk factor for new CVD events. Pre–β-1 level was a significant risk factor for new CVD events only in univariate analysis. A forward selection model indicated that α-1 was the most significant risk factor for recurrent CVD events among HDL particles.

Conclusions— An altered HDL subpopulation profile marked with low α-1 and α-2 levels and a high α-3 level in coronary heart disease patients indicated an elevated risk for new CVD events. Moreover, α-1 and α-2 levels were superior to HDL-C levels in risk assessment in patients with low HDL-C in VA-HIT.

Body mass index and high-density lipoproteins in Cherokee Indian children and adolescents

Native Americans are predisposed to insulin resistance and associated cardiovascular risk. Therefore, we studied whether BMI (body mass index) in a population of Cherokee children and adolescents is associated with HDL-C (HDL cholesterol), and the HDL particles Lp (lipoprotein) A-I and LpA-I:A-II. Subjects were grouped by BMI Z score quartiles within three gender-specific age brackets (5-9, 10-14, and 15-19 y) to examine for trends in lipoprotein and HOMA-IR (homeostasis index insulin resistance) values associated with adiposity and age. HDL-C decreased by BMI Z score quartiles in all three age groups for both genders. HDL-C, LpA-I, and LpA-I:A-II decreased with age in boys but not girls. Log HOMA-IR increased by BMI Z score quartiles in all three age groups for both genders. Linear regression modeling showed BMI Z score, triglyceride, and age to be associated with HDL-C, whereas HOMA-IR was associated with LpA-I:A-II but not with HDL-C or LpA-I. When waist circumference was substituted for BMI Z score in the same models, it was associated with HDL-C and both lipoprotein particles. In conclusion, adiposity is more associated with HDL-C lowering than with declines in the lipoprotein particles. HOMA-IR is less associated with HDL-C but may selectively influence LpA-I:A-II. Greater decreases in HDL-C, LpA-I, and LpA-I:A-II with age in boys is attributed to gender-specific hormonal changes. The early onset of HDL lowering in these Native American children and adolescents, particularly boys, warrants intervention strategies to prevent obesity and associated cardiovascular risk.

Pre-hospital coronary care and coronary fatality in the Belfast and Glasgow MONICA populations

BACKGROUND

The aim of this study was to describe and compare coronary event case fatality and care pathways in two defined populations with access to different models of pre-hospital care provision.

METHODS

Secondary analysis of MONItoring of Trends and Determinants in CArdiovascular Disease (MONICA) population coronary event registers (1988, 1989, 1990, 1992 and 1993).

RESULTS

Case fatality at 28 days following an acute coronary event was 6.5% greater in the Glasgow MONICA Project (GMP) population (46.7%) than in the Belfast MONICA Project (BMP) population (40.2%). Pre-hospital case fatality was 33.9% in the GMP population and 28.3% in the BMP population. These differences could not be fully explained by mobile coronary care unit (MCCU) responses in the BMP area. Initial care was provided in hospital for 28.3% of the BMP events and only 7.7% of the GMP events. Additional data collected by the Belfast and Glasgow MONICA investigators support a large difference between the median delay to main medical care in the BMP events (120 min) and the median delay to ward admission in the GMP area (220 min) at this time.

CONCLUSIONS

Our findings suggest that the delay between coronary event onset and access to specialist coronary care was the most likely critical difference, irrespective of hospital-based MCCU provision in the BMP area. An established 'culture of early intervention' in Belfast may have been an important factor. As a large proportion of coronary event fatalities continue to occur outside hospital, there is a need to strengthen the evidence base underpinning the provision of appropriate skilled care and treatment at the earliest possible opportunity.

Exploration of multilocus effects in a highly polymorphic gene, the apolipoprotein (APOB) gene, in relation to plasma apoB levels

A detailed exploration of all the polymorphisms in candidate genes is required to better characterize the relationship between gene variability and complex traits. We propose a novel strategy for investigating the association between a highly polymorphic gene and a phenotype, by combining a multilocus genotype analysis and an haplotype analysis. For the multilocus genotype analysis, a data mining tool--termed DICE (Detection of Informative Combined Effects)--was developed to identify the best subset of polymorphisms that are associated--individually or in combination--with the phenotype. For the haplotype analysis, we used our recently developed method of haplotype-phenotype association to determine the most informative and parsimonious haplotype model fitting the data. We illustrate this strategy by investigating the association between twelve polymorphisms of the APOB gene and plasma apoB levels in 1442 European subjects. After exploring all main effects and interactions between polymorphisms, DICE identified the N4311S polymorphism as the most informative polymorphism in relation to apoB levels. Haplotype analysis led to the same conclusion. Additionally, DICE identified the E4154K (EcoRI) and the T2488T (XbaI) polymorphisms as potentially interesting. This selection was not modified by inclusion of the common APOE polymorphism in the analysis.

High-Density Lipoprotein Subpopulation Profile and Coronary Heart Disease Prevalence in Male Participants of the Framingham Offspring Study

OBJECTIVE

High-density lipoprotein (HDL) is a heterogeneous lipoprotein class and there is no consensus on the value of HDL subspecies in coronary heart disease (CHD) risk assessment. We tested the hypothesis whether specific HDL subpopulations are significantly associated with CHD-prevalence.

METHODS AND RESULTS

ApoA-I concentrations (mg/dL) in HDL subpopulations were quantitatively determined by native 2d gel electrophoresis, immunoblotting, and image analysis in male participants in the Framingham Offspring Study (FOS). CHD cases (n=169) had higher prebeta-1 and alpha-3 particle and lower alpha-1, prealpha-3, and prealpha-1 particle levels than either all (n=1277) or HDL cholesterol-matched (n=358) controls. alpha-1 and prealpha-3 levels had an inverse association, whereas alpha-3 and prealpha-1 particle levels had a positive association with CHD prevalence after adjusting the data for established CHD risk factors. Standardized logit coefficients indicated that alpha-1 HDL was most significantly associated with CHD prevalence. Moreover, each mg/dL increase in alpha-1 particle level decreased odds of CHD by 26% (P<0.0001), whereas each mg/dL increase in HDL cholesterol decreased odds of CHD by 2% in a model including all established CHD risk factors.

CONCLUSIONS

Specific HDL subpopulations were positively correlated, whereas others were inversely correlated with CHD prevalence in male subject in the FOS, indicating that the various HDL particles might have different roles in the cause of CHD.

In vitro transcriptional induction of the human apolipoprotein A-II gene by glucose

Type 2 diabetic patients present high triglyceride and low HDL levels, significant determinants for the risk of atherosclerosis. Transgenic mice overproducing human apolipoprotein (apo)A-II, one of the two major apos of HDLs, display the same lipid disorders. Here, we investigated the possible regulation of apoA-II gene expression by glucose. In primary rat hepatocytes and in HepG2 cells, the transcription of the human apoA-II gene was upregulated by glucose. This response was mediated by a hormone-responsive element within the enhancer of the apoA-II promoter and was dependent on hepatocyte nuclear factor-4alpha. Accordingly, in transgenic mice, the human apoA-II gene is stimulated by a high-carbohydrate diet after fasting and at weaning. By contrast, the apoA-II mRNA level is not modified in streptozotocin-induced diabetic rats. In transgenic mice overexpressing the human apoA-II gene, plasma human apoA-II concentration was positively correlated with blood glucose levels. These mice displayed a marked delay in plasma glucose tolerance as compared with control mice. We hypothesize that the following pathogenic pathway might occur in the course of type 2 diabetes: increased apoA-II level causes a rise in plasma triglyceride level and glucose intolerance, resulting in hyperglycemia, which in turn might further increase apoA-II gene transcription.

Residual coronary risk in men aged 50–59 years treated for hypertension and hyperlipidaemia in the population

OBJECTIVE

Since the proportion of subjects taking antihypertensive and lipid-lowering drugs is currently increasing in industrialized countries, it is important to evaluate, at the population level, coronary risk of treated individuals, while taking into account the achieved level of their risk factors (i.e. their 'residual coronary risk').

DESIGN AND METHODS

We used the data from the Prospective Study of Myocardial Infarction (PRIME), which involved populations from France (three centres) and Northern Ireland (one centre) (in each centre, 2500 men, aged 50-59 years, free of coronary heart disease, with a 5-year follow-up), to analyse the relationships between cardiovascular drug use and subsequent coronary risk.

RESULTS

Antihypertensive drug use was significantly positively associated (relative risk = 1.60; 95% confidence interval, 1.18-2.16) with total coronary risk, but not lipid-lowering drug use (relative risk = 1.15; 95% confidence interval, 0.77-1.73), while adjusting on classical risk factor levels (age, smoking, total cholesterol, high-density lipoprotein-cholesterol and systolic blood pressure). Subgroup analysis showed that these results applied to beta-blockers and calcium channel antagonists, but not to diuretics and angiotensin-converting enzyme inhibitors, to both angina pectoris and hard coronary event risk, but in the French population only and not in Belfast. Although the PRIME study was not designed to test the ability of different drugs to prevent coronary heart disease, this analysis raises the hypothesis that antihypertensive drugs could be associated with a sizeable residual coronary risk in middle-aged men.

CONCLUSION

Treatment with antihypertensive agents, beta-blockers and calcium channel antagonists in particular, was associated with a sizeable residual coronary risk. It seems, therefore, important to consider antihypertensive treatment in the cardiovascular risk assessment of individuals.

Polymorphism R92Q of the tumour necrosis factor receptor 1 gene is associated with myocardial infarction and carotid intima-media thickness – The ECTIM, AXA, EVA and GENIC Studies

The TNFRSF1A gene was screened for polymorphisms in 95 subjects with premature myocardial infarction (MI), who also had one parent who had an MI. A total of 10 polymorphisms were found: three in the promoter region, two in exons and five in introns. All polymorphisms were genotyped in ECTIM, a case-control study of MI (1815 subjects). The nonsynonymous 92Q allele was found in 1.8, 1.0 and 1.7% of controls from Strasbourg, Belfast and Glasgow - respectively; in cases: 4.2, 2.2 and 3.2%. The population-adjusted odds ratio (OR) for MI associated with allele Q carrying was 2.15 (95% CI: 1.09-4.23). To check its possible implication in atherosclerosis, this polymorphism was then genotyped in the AXA Study (ultrasound examinations of carotid and femoral arteries in the context of an employment medical examination, 733 subjects), the EVA Study (ultrasound examinations of carotid arteries in a study of cognitive and vascular ageing, 1092 subjects) and the GENIC Study (on brain infarction (BI), 912 subjects). In the AXA Study, among smokers, carrying the 92Q allele was positively associated with the presence of a carotid plaque (OR 5.07; 95% CI: 1.64-15.63) and with a thickening of the carotid intima-media thickness (IMT) (0.59 (0.11) vs 0.54 (0.11), P=0.045). In the EVA Study, carriers of allele 92Q had an increased mean carotid IMT (0.70 (0.09) vs 0.67 (0.13), P=0.02). No significant association of the 92Q allele was found with BI in the GENIC Study. Overall, these results may suggest that carriers of the 92Q allele may be at increased risk of atherosclerosis.

Associations of plasma fibrinogen assays, C-reactive protein and interleukin-6 with previous myocardial infarction

BACKGROUND

The association of plasma fibrinogen with myocardial infarction (MI) may (like that of C-reactive protein, CRP) be a marker of subclinical inflammation, mediated by cytokines such as interleukin-6 (IL-6). There are well-recognized discrepancies between commonly performed fibrinogen assays. Increased ratio of clottable fibrinogen to intact fibrinogen (measured by a recently developed immunoassay) has been proposed as a measure of hyperfunctional fibrinogen, and is elevated in acute MI.

OBJECTIVE

To compare the associations of intact fibrinogen and four routine fibrinogen assays (two von Clauss assays; one prothrombin-time derived; and one immunonephelometric) in a case-control study of previous MI.

PATIENTS/METHODS

Cases (n=399) were recruited 3-9 months after their event; 413 controls were age- and sex- matched from the case-control study local population. Intact fibrinogen was measured in 50% of subjects.

RESULTS

All routine fibrinogen assays showed high intercorrelations (r=0.82-0.93) and significant (P<0.0001) increased mean levels in cases vs. controls. These four routine assays correlated only moderately with intact fibrinogen (r=0.45-0.62), while intact fibrinogen showed only a small, nonsignificant increase in cases vs. controls. Consequently, the ratio of each of the four routine assays to the intact fibrinogen assay was significantly higher (P<0.0003) in cases vs. controls. Each fibrinogen assay correlated with plasma levels of CRP and IL-6 (which were also elevated in cases vs. controls). Each routine fibrinogen assay remained significantly elevated in cases vs. controls after further adjustment for C-reactive protein and interleukin-6.

CONCLUSIONS

These data provide evidence for acquired, increased hyperfunctional plasma fibrinogen in MI survivors, which is not associated with markers of inflammatory reactions. The causes and significance of these results remain to be established in prospective studies.

Effects of estrogen and medroxyprogesterone acetate on subpopulations of triglyceride-rich lipoproteins and high-density lipoproteins

Hormonal replacement therapy (HRT) in postmenopausal women has been shown to increase both triglyceride (TG) and high-density lipoprotein (HDL) cholesterol levels. To better understand the effects of conjugated equine estrogen (CEE) and medroxyprogesterone acetate (MPA), the 2 most commonly prescribed hormones in HRT, on the different subpopulations of TG-rich and HDL lipoproteins, we conducted a placebo-controlled, double-blind, randomized, crossover study consisting of 3 different phases in 14 postmenopausal women. The 3 phases, each 8-week long, included: (1) placebo, (2) CEE 0.625 mg/d, and (3) CEE 0.625 mg/d and MPA 2.5 mg/d. Slight and statistically nonsignificant elevations in TG levels were observed during the CEE treatment. While very-low-density lipoprotein (VLDL) cholesterol levels were not significantly affected by CEE and CEE + MPA, both HRT treatments lowered remnant lipoprotein (RLP) cholesterol (-14% and -37%, respectively). Compared with placebo, CEE caused a significant increase in HDL, HDL(2), apolipoprotein (apo) A-I, LpAI, alpha1, and prealpha1 levels (12%, 27%, 17%, 26%, 60%, and 102%, respectively). The combination therapy blunted the CEE effect on all HDL parameters, resulting in HDL, HDL(2), and LpAI levels being no longer significantly different from placebo. Apo A-I levels and alpha1, and prealpha1 levels were still significantly higher than placebo (+11%, +50%, and +112%, respectively). These results indicate that HRT has beneficial effects on RLP levels and that, while the estrogen component of HRT has a beneficial effect on the HDL subpopulations mostly associated with coronary heart disease (CHD) protection, MPA partially inhibits this effect.

Cholesteryl ester transfer protein: gathering momentum as a genetic marker and as drug target

PURPOSE OF REVIEW

Cholesteryl ester transfer protein facilitates the exchange of neutral lipids between HDL and apolipoprotein B containing lipoproteins, which hold powerful opposing roles as risk factors for coronary artery disease. The question as to whether cholesteryl ester transfer protein promotes or protects from atherosclerosis, however, has not been answered.

RECENT FINDINGS

This review considers studies dealing with cholesteryl ester transfer protein variants and their effect on blood lipids in various metabolic and clinical settings. Other studies discussed deal with the association between the transfer protein and cardiovascular disease. Research on the biological activity of the cholesteryl ester transfer protein molecule is described including a first clinical study where pharmacological inhibition of the protein proved to be effective in raising HDL cholesterol.

SUMMARY

Data concerning the potential marker role of cholesteryl ester transfer protein, although accumulating, are still inconclusive and, at present, not useful for clinical decision making. Inhibition of the protein was demonstrated to be feasible and appears to be promising.

HDL in atherosclerosis: actor or bystander?

Despite dramatic improvement in treatments for reducing risk for coronary heart disease (CHD), it is still the leading cause of mortality in the developed world. In the past decade, a major improvement in reducing low-density lipoprotein (LDL) cholesterol has been achieved with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins). This approach has been shown to be beneficial in both primary and secondary prevention of CHD. On the other hand, while a reduced high-density lipoprotein (HDL) cholesterol level is an independent CHD risk factor, no HDL cholesterol goal has yet been established. The Helsinki Heart Study and the Veterans Affairs High-density Lipoprotein Intervention Trial documented that increasing HDL cholesterol with gemfibrozil significantly decreases coronary events or stroke in CHD patients either with elevated non-HDL cholesterol or normal LDL cholesterol levels plus low HDL cholesterol. Investigations with statins have focused on their efficacy not only in significantly decreasing total cholesterol, LDL cholesterol, and triglyceride levels but also in increasing HDL cholesterol concentrations. The two different classes of drugs (statins and fibrates) have different effects on the various HDL subspecies. As new members of these drug classes and other novel drugs are emerging, there is interest in clarifying whether HDL is only a bystander (an indicator for other CHD risk factors) or it has an active role in the development of CHD. If HDL has an active role, there is a need to determine if any HDL subspecies are protective. It is now clear that HDL plays a pivotal role in cellular cholesterol efflux via the interaction of apolipoprotein A-I with the ATP binding cassette transporter A-1. Thereafter the cholesterol is esterified by lecithin:cholesterol acyltransferase; HDL is remodeled by cholesterol ester transfer protein (CETP) and hepatic lipase. The cholesterol in HDL can either be transferred to apolipoprotein B-containing particles via CETP or delivered directly to the liver with the help of scavenger receptor B1.