Is the influence of variation in the ACE gene on the prospective risk of Type 2 diabetes in middle-aged men modified by obesity?

There is strong evidence for the presence of a functional renin-angiotensin system in diabetogenic tissues, and ACE (angiotensin-converting enzyme) inhibitors may improve glucose metabolism in those individuals at high risk of developing T2DM (Type 2 diabetes). In the present study, we tested the hypothesis that subjects with genetically lower plasma and tissue ACE activity, because of their ACE [I/D (insertion/deletion)] genotype, would have a lower risk of T2DM in 2642 healthy middle-aged Caucasian men (mean age, 56 years) followed-up for 15 years. Obesity was the strongest predictor of T2DM, with an HR (95% CI) [hazard ratio (95% confidence interval)] of 3.74 (2.66-5.26) (P<0.0001). Overall there was no association between ACE genotype (II homozygotes, n=623; and D allele carriers, n=2019) and risk of T2DM, and although in lean men there was no genotype difference in risk in D allele carriers compared with II homozygotes [adjusted HR=0.75 (95% CI, 0.46-1.22)], in obese (body mass index >30 kg/m(2)) men the risk of T2DM was higher [adjusted HR=4.26 (95% CI, 1.30-13.93)] with a genotype-obesity interaction of P=0.01. A similar pattern of risk was seen by re-analysis of a previously published case-control study, where D allele carriers had a non-significant 1.30 (0.97-1.74)-fold higher risk of developing T2DM than II homozygotes when non-obese, but a 1.79 (1.17-2.72) (P=0.007)-fold higher risk when obese. Further prospective studies are needed to confirm these findings. The ACE D allele may worsen glucose metabolism, which could raise the prospective T2DM risk in obese men, but not in lean men. In obesity, adipose tissue undergoes inflammatory infiltration and the subsequent higher levels of pro-inflammatory angiotensin II may explain this association.

The solid fat content of stearic acid-rich fats determines their postprandial effects.

BACKGROUND: The process of randomization is used commercially to harden fats as an alternative to partial hydrogenation, but its effects on cardiovascular disease risk factors are uncertain. OBJECTIVE: The objective was to compare the chronic and acute effects of randomization of a fat rich in 1,3-distearyl, 2-oleyl glycerol on fasting and postprandial lipids, glucose, insulin, and activated clotting factor VII (FVIIa) concentrations. DESIGN: A crossover design study in 16 men compared fasting and postprandial lipid, glucose, insulin, and FVIIa concentrations at baseline and after a 3-wk diet providing 30 g unrandomized or randomized shea butter and sunflower oil blends (SSOBs), both of which contained approximately 50% stearic acid. Fecal fat excretion was measured during each dietary period. Postprandial changes were assessed after the consumption of meals providing 50 g test fat. A subsequent study compared postprandial changes after the consumption of an oleic acid-rich sunflower oil meal and an unrandomized SSOB meal. RESULTS: Both SSOBs were well digested and absorbed. Randomization did not affect fasting or postprandial lipid, glucose, insulin, or FVIIa concentrations. Compared with the oleic acid-rich meal, the unrandomized SSOB resulted in 53% lower postprandial lipemia, 23% higher hepatic lipase activity, and a 25% lower postprandial increase in FVIIa concentration. The solid fat contents at 37 degrees C were 22%, 41%, and 0% with the unrandomized SSOB, randomized SSOB, and oleic acid-rich meals, respectively. CONCLUSIONS: Stearic acid-rich triacylglycerol in both unrandomized and randomized forms does not adversely affect lipid risk factors for cardiovascular disease. The high proportion of solid fat at 37 degrees C may explain the decreased postprandial lipemic response.

Effect of interesterification of palmitic acid-rich triacylglycerol on postprandial lipid and factor VII response.

The process of interesterification results in changes in triacylglycerol (TAG) structure and is used to increase the melting point of dietary fats. The acute health effects of this process on palmitic acid-rich fats are uncertain with regard to postprandial lipemia, insulin and factor VII activated (FVIIa) concentrations. Two randomized crossover trials in healthy male subjects compared the effects of meals containing 50 g fat [interesterified palm oil (IPO) versus native palm oil (NPO); n=20, and IPO versus high-oleic sunflower oil (HOS); n=18], on postprandial changes in lipids, glucose, insulin, chylomicron composition and FVIIa. Compared with NPO, IPO decreased postprandial TAG and insulin concentrations. Both NPO and IPO increased FVIIa concentrations postprandially; mean increases at 6 h were 21 and 19%, respectively. Compared with HOS, IPO decreased postprandial TAG (47% lower incremental area under the curve) and reduced the postprandial increase in FVIIa concentration by 64% at 6 h; no significant differences in hepatic and total lipase activities or insulin concentrations were noted. All three test meals increased postprandial leukocyte counts (average 26% at 6 h). The fatty acid composition of the chylomicron TAG was similar to the test fats following all test meals. It is concluded that interesterification of palm oil does not result in adverse changes in postprandial lipids, insulin or FVIIa compared to high oleate and native palm oils.

A common interleukin 18 haplotype is associated with higher body mass index in subjects with diabetes and coronary heart disease.

The pleiotropic proinflammatory cytokine, interleukin 18, plays a role in innate immunity and, based on mouse models, influences obesity. We investigated variation within the IL18 gene and its effect on markers of the metabolic syndrome. A tagging single nucleotide polymorphism set of 5 SNPs for the gene encoding interleukin 18 was selected and genotype was determined in 3 separate studies. In 2775 healthy middle-aged men, 6 common haplotypes were seen, but none was associated with body mass index (BMI). In 439 patients who underwent coronary artery bypass graft surgery, Hap2 (frequency, 22%) was present at a lower frequency than in healthy subjects and was associated with higher mean BMI compared with Hap1 (P = .011). In 483 men with type 2 diabetes mellitus, Hap2 was again associated with a higher haplotypic mean BMI (P = .002). Those homozygous for Hap2 had a BMI of 31.2 (1.3) kg/m(2), mean (SE), compared with 28.3 (1.0) kg/m(2) in those not carrying a copy of Hap2. No single SNP could fully explain the effects seen. Therefore, variation within IL18, previously shown to be associated with lower IL18 levels, is influencing measures of obesity both in men with type 2 diabetes mellitus and those with advanced coronary heart disease.

Candidate gene genotypes, along with conventional risk factor assessment, improve estimation of coronary heart disease risk in healthy UK men.

BACKGROUND: One of the aims of cardiovascular genetics is to test the efficacy of the use of genetic information to predict cardiovascular risk. We therefore investigated whether inclusion of a set of common variants in candidate genes along with conventional risk factor (CRF) assessment enhanced coronary heart disease (CHD)-risk algorithms. METHODS: We followed middle-aged men in the prospective Northwick Park Heart Study II (NPHSII) for 10.8 years and analyzed complete trait and genotype information available on 2057 men (183 CHD events). RESULTS: Of the 12 genes previously associated with CHD risk, in stepwise multivariate risk analysis, uncoupling protein 2 (UCP2; P = 0.0001), apolipoprotein E (APOE; P = 0.0003), lipoprotein lipase (LPL; P = 0.007), and apolipoprotein AIV (APOA4; P = 0.04) remained in the model. Their combined area under the ROC curve (A(ROC)) was 0.62 (0.58-0.66) [12.6% detection rate for a 5% false positive rate (DR(5))]. The A(ROC) for the CRFs age, triglyceride, cholesterol, systolic blood pressure, and smoking was 0.66 (0.61-0.70) (DR(5) = 14.2%). Combining CRFs and genotypes significantly improved discrimination (P = 0.001). Inclusion of previously demonstrated interactions of smoking with LPL, interleukin-6 (IL6), and platelet/endothelial cell adhesion molecule (PECAM1) genotypes increased the A(ROC) to 0.72 (0.68-0.76) for a DR(5) of 19.1% (P = 0.01 vs CRF combined with genotypes). CONCLUSIONS: For a modest panel of selected genotypes, CHD-risk estimates incorporating CRFs and genotype-risk factor interactions were more effective than risk estimates that used CRFs alone.

Effects of altering the ratio of dietary n-6 to n-3 fatty acids on insulin sensitivity, lipoprotein size, and postprandial lipemia in men and postmenopausal women aged 45-70 y: the OPTILIP Study.

BACKGROUND: Insulin resistance is associated with elevated plasma triacylglycerol, low HDL concentrations, elevated postprandial lipemia, and a predominance of small, dense LDLs (sdLDLs). It has been hypothesized that the dietary ratio of n-6 to n-3 (n-6:n-3) polyunsaturated fatty acids (PUFAs) may have favorable effects on these risk factors by increasing insulin sensitivity. OBJECTIVE: The objective was to measure changes in insulin sensitivity, lipoprotein size, and postprandial lipemia after a 6-mo alteration in n-6:n-3. DESIGN: In a randomized, parallel design in 258 subjects aged 45-70 y, we compared 4 diets providing 6% of energy as PUFAs with an n-6:n-3 between 5:1 and 3:1 with a control diet that had an n-6:n-3 of 10:1. The diets were enriched in alpha-linolenic acid, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), or both. Insulin sensitivity was assessed with the homeostatic model assessment of insulin resistance and the revised quantitative insulin sensitivity test. RESULTS: Dietary intervention did not influence insulin sensitivity or postprandial lipase activities. Fasting and postprandial triacylglycerol concentrations were lower, and the proportion of sdLDLs decreased (by 12.7%; 95% CI: -22.9%, 2.4%), with an n-6:n-3 of approximately 3:1, which was achieved by the addition of long-chain n-3 PUFAs (EPA and DHA). CONCLUSIONS: Decreasing the n-6:n-3 does not influence insulin sensitivity or lipase activities in older subjects. The reduction in plasma triacylglycerol after an increased intake of n-3 long-chain PUFAs results in favorable changes in LDL size.

Oily fish reduces plasma triacylglycerols: a primary prevention study in overweight men and women.

OBJECTIVE: Previous studies have demonstrated benefits of high-dose long-chain omega-3 polyunsaturated fatty acid (LC omega-3 PUFA) supplements on metabolic risk. Effects of increased dietary omega-3 PUFA, via oily fish and/or plant-derived omega-3 PUFAs, are less clear and may be modulated by the omega-6:omega-3 PUFA of the habitual diet. This study examined the effect on cardiovascular disease risk markers of reducing dietary omega-6:omega-3 PUFA by changes in linoleic acid:alpha-linolenic acid (LA:LNA) and/or increasing LC omega-3 PUFA. It tested whether decreases in LA:LNA modulate effects of LC omega-3 PUFA. METHODS: One hundred forty-two subjects, recruited to a 24-wk randomized study, were assigned to a control group or one of four interventions. Intervention groups received two portions of oily fish (4.5 g eicosapentaenoic acid + docosahexanoic acid) or white fish (0.7 g eicosapentaenoic acid + docosahexanoic acid) per week, and replaced habitual household fats with ones high in sunflower (high LA:LNA) or rapeseed (low LA:LNA) oil. RESULTS: Modest dietary manipulations of omega-6 and omega-3 PUFAs resulted in significant group x time interactions for serum triacylglycerols (TAGs; P = 0.05); at 24 wk the control and two oily fish groups showed lower TAG than did the white fish/sunflower group (P = 0.05). Reductions in TAG, associated with increased oily fish intakes, were maximized when combined with lower dietary LA:LNA. There were no significant changes in several other cardiovascular disease risk markers. CONCLUSIONS: Two portions of oily fish per week led to significant reductions in TAG relative to consumption of two portions of white fish per week. Changes in TAG were maximized when combined with lower LA:LNA.

The A370T variant (StuI polymorphism) in the LDL receptor gene is not associated with plasma lipid levels or cardiovascular risk in UK men.

Over 800 different missense mutations in the low density lipoprotein (LDL) receptor gene (LDLR) have been identified in patients with familial hypercholesterolaemia (FH). Only two of them, including the Alanine to Threonine change at position 370 (A370T), have been discovered in FH patients but do not cause FH. The frequency of the 370T allele has been reported worldwide to be between 0.022 and 0.070, with no clear association with high cholesterol levels or risk for coronary heart disease (CHD) and stroke. To explore this relationship in more detail we have determined this genotype in 2,659 healthy middle-aged (50-61 years) men participating in the prospective Second Northwick Park Heart Study, with 236 CHD and 67 stroke incident events. The genotype distribution was in Hardy-Weinberg equilibrium and in the no-event group the frequency of 370T was 0.046 (95% CI 0.040-0.052). Overall, there was no significant association of the 370T allele with any measured plasma lipid trait, and there was no difference in genotype distribution or allele frequency between the no-event and CHD (0.059; 95% CI 0.040-0.085) or stroke (0.037; 95% CI 0.012-0.085) groups ( p= 0.18 and 0.65, respectively). There was evidence for significant interaction ( p= 0.006) between body mass index (BMI) and genotype on CHD risk, with 370A homozygotes showing the expected higher CHD risk for those with higher BMI, whilst risk for 370T allele carriers was highest in men in the lowest tertile of BMI. The explanation for this association is unclear, and may simply be chance. Thus, these data confirm the absence of a significant impact of the A370T polymorphism on LDL receptor function, at least as measured by the effect on plasma lipid levels and CHD risk.

IL6 gene promoter polymorphisms and type 2 diabetes: joint analysis of individual participants' data from 21 studies.

Several lines of evidence indicate a causal role of the cytokine interleukin (IL)-6 in the development of type 2 diabetes in humans. Two common polymorphisms in the promoter of the IL-6 encoding gene IL6, -174G>C (rs1800795) and -573G>C (rs1800796), have been investigated for association with type 2 diabetes in numerous studies but with results that have been largely equivocal. To clarify the relationship between the two IL6 variants and type 2 diabetes, we analyzed individual data on >20,000 participants from 21 published and unpublished studies. Collected data represent eight different countries, making this the largest association analysis for type 2 diabetes reported to date. The GC and CC genotypes of IL6 -174G>C were associated with a decreased risk of type 2 diabetes (odds ratio 0.91, P = 0.037), corresponding to a risk modification of nearly 9%. No evidence for association was found between IL6 -573G>C and type 2 diabetes. The observed association of the IL6 -174 C-allele with a reduced risk of type 2 diabetes provides further evidence for the hypothesis that immune mediators are causally related to type 2 diabetes; however, because the association is borderline significant, additional data are still needed to confirm this finding.

Effect of varying the ratio of n-6 to n-3 fatty acids by increasing the dietary intake of alpha-linolenic acid, eicosapentaenoic and docosahexaenoic acid, or both on fibrinogen and clotting factors VII and XII in persons aged 45-70 y: the OPTILIP study.

BACKGROUND: Elevated fibrinogen, activated factor XII (FXIIa), and factor VII coagulant activity (FVIIc) are associated with higher risk of fatal ischemic heart disease. This study tested the hypothesis that lowering the dietary ratio of n-6 to n-3 polyunsaturated fatty acids (n-6:n-3) would modify these risk factors in older men and women. OBJECTIVE: The objective of the study was to measure fasting hemostatic risk factors and postprandial changes in activated FVII (FVIIa) concentrations after a 6-mo alteration in dietary n-6:n-3. DESIGN: In a randomized, parallel design in 258 subjects aged 45-70 y, we compared 4 diets providing 6% of energy as polyunsaturated fatty acids at an n-6:n-3 between 5:1 and 3:1 with a control diet that had an n-6:n-3 of 10:1. The diets were enriched in alpha-linolenic acid, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acid, or both. RESULTS: Fasting and 3-h plasma triacylglycerol concentrations were 11.1% and 7.2% lower with the diet that had an n-6:n-3 of approximately 3:1 and that was enriched with EPA and DHA than with the other diets. Fasting fibrinogen, FXIIa, FVIIc, FVIIa, and FVII antigen and postprandial FVIIa were not influenced by the diets. Avoiding foods high in fat the day before measurement decreased FVIIc and FVIIa by 8% and 19.2%, respectively. A test meal containing 50 g fat resulted in a mean 47% (95% CI: 42%, 52%) increase in FVIIa 6 h later, but the response did not differ by n-6:n-3. CONCLUSION: Decreasing the n-6:n-3 to approximately 3:1 by increasing the intake of EPA and DHA lowers fasting and postprandial plasma triacylglycerol concentrations in older persons but does not influence hemostatic risk factors.

Investigating the genetic determinants of cardiovascular disease using candidate genes and meta-analysis of association studies.

Coronary artery disease (CAD) has a polygenic basis, and identification of CAD susceptibility genes has the potential to aid the development of new treatments and enhance prediction of disease risk. Thus far, the strategy has firstly been to choose "candidate" genes coding for important "rate-limiting" proteins in the homeostatic systems involved in maintaining cardiovascular health; secondly to identify common variants in these candidate genes; thirdly to carry out genotyping and statistical analysis using genetic association studies; and finally to test the functional effects of the identified variants in vitro and in vivo. However, lack of reproducibility of genetic association studies has led to uncertainty about the nature and number of genes involved. In part this is because many of the studies conducted have not been adequately powered to detect small risk effects, or to permit adequate exploration of gene-gene or gene-environment interactions in a robust manner. Spurious positive and negative associations due to type I and type II statistical errors are likely to co-exist with real associations in the published literature. By utilising all available data to increase statistical power, meta-analysis of genetic association studies is increasingly being used to identify genotypic risk with a greater degree of precision. Though potentially powerful, this approach may be prone to publication bias. Therefore, very large genetic association studies will also be required to identify risk genes for CAD. This review lays out the framework for the candidate gene approach for CAD and illustrates this with published results from a UK prospective study of 3000 middle-aged men.

Variation in the UCP2-UCP3 gene cluster predicts the development of type 2 diabetes in healthy middle-aged men.

The impact of the UCP2 -866G>A and UCP3 -55C>T variants on prospective risk of type 2 diabetes was examined over 15 years in 2,936 healthy middle-aged men (mean age 56 years). Conversion to diabetes (n = 169) was associated with higher BMI, blood pressure, cholesterol, triglycerides and C-reactive protein. The hazard ratio (HR) for diabetes of a BMI >30 kg/m(2) was 3.96 (95% CI 2.87-5.47). Homozygosity for the UCP2A or UCP3T alleles accelerated the onset of diabetes, with significant differences in risk of diabetes at 10 years (HR [95% CI] UCP2AA vs. GA+GG 1.94 [1.18-3.19], P = 0.009; UCP3TT vs. CC+ CT 2.06 [1.06-3.99], P = 0.03) but less so at 15 years (UCP2AA 1.42 [0.92-2.19], P = 0.1; UCP3TT 1.57 [0.87-2.04], P = 0.13). Men who were homozygous for both UCP2AA and UCP3TT (1.5% of men) had a risk for diabetes at 10 years of 4.20 (1.70-10.37), P = 0.002. These genotype effects were additive with obesity, and men with a BMI >30 kg/m(2) and this genotype combination had a 10-year risk of diabetes of 19.23 [5.63-63.69], P < 0.0001. Functional promoter variants UCP2 and UCP3 increase the prospective risk of diabetes. Although the mechanism of the UCP2 effect is likely to be caused by increased expression in the pancreas and subsequent reduced insulin secretion, the mechanism of the UCP3 effect is currently unknown. Both effects are exacerbated by obesity.

Influence of an algal triacylglycerol containing docosahexaenoic acid (22 : 6n-3) and docosapentaenoic acid (22 : 5n-6) on cardiovascular risk factors in healthy men and women.

The intake of long-chain n-3 PUFA, including DHA (22 : 6n-3), is associated with a reduced risk of CVD. Schizochytrium sp. are an important primary source of DHA in the marine food chain but they also provide substantial quantities of the n-6 PUFA docosapentaenoic acid (22 : 5n-6; DPA). The effect of this oil on cardiovascular risk factors was evaluated using a double-blind randomised placebo-controlled parallel-design trial in thirty-nine men and forty women. Subjects received 4 g oil/d for 4 weeks; the active treatment provided 1.5 g DHA and 0.6 g DPA. Active treatment increased plasma concentrations of arachidonic acid, adrenic acid, DPA and DHA by 21, 11, 11 and 88 mg/l respectively and the proportions of DPA and DHA in erythrocyte phospholipids by 78 and 27 % respectively. Serum total, LDL- and HDL-cholesterol increased by 0.33 mmol/l (7.3 %), 0.26 mmol/l (10.4 %) and 0.14 mmol/l (9.0 %) compared with placebo (all P < or =0.001). Factor VII (FVII) coagulant activity increased by 12 % following active treatment (P = 0.006). There were no significant differences between treatments in LDL size, blood pressure, plasma glucose, serum C-reactive protein, plasma FVII antigen, FVII activated, fibrinogen, von Willebrand factor, tocopherol or carotenoid concentrations, plasminogen activator inhibitor-1, creatine kinase or troponin-I activities, haematology or liver function tests or self-reported adverse effects. Overall, the oil was well tolerated and did not adversely affect cardiovascular risk.

Insight into the nature of the CRP-coronary event association using Mendelian randomization.

BACKGROUND: It is unclear wheather the association between C-reactive protein (CRP) and incident coronary events is free from bias and confounding. Individuals homozygous for a +1444C>T polymorphism in the CRP gene have higher circulating concentrations of CRP. Since the distribution of this polymorphism occurs at random during gamete formation, its association with coronary events should not be biased or confounded. METHODS: We calculated the weighted mean difference in CRP between individuals with variants of the +1444C>T polymorphism in the CRP gene among 4,659 European men from six studies (genotype-intermediate phenotype studies). We used this difference together with data from previous observational studies to compute an expected odds ratio (OR) for non-fatal myocardial infarction (MI) among individuals homozygous for the T allele. We then performed four new genetic association studies (6,201 European men) to obtain a summary OR for the association between the +1444C>T polymorphism and non-fatal MI (genotype-disease studies). RESULTS: CRP was 0.68 mg/l [95% confidence interval (95% CI) 0.31-1.10; P = 0.0001] higher among subjects homozygous for the +1444-T allele, with no confounding by a range of covariates. The expected ORs among TT subjects for non-fatal MI corresponding to this difference in CRP was 1.20 (95% CI 1.07-1.38) using the Reykjavik Heart study data and 1.25 (1.09-1.43) for all observational studies to 2004. The estimate for the observed adjusted-OR for non-fatal MI among TT subjects was 1.01 (95% CI 0.74-1.38), lower than both expected ORs. CONCLUSIONS: A common CRP gene polymorphism is associated with important differences in CRP concentrations, free from confounding. The null association of this variant with coronary events suggests possible residual confounding (or reverse causation) in the CRP-coronary event association in observational studies, though the confidence limits are still compatible with a modest causal effect. Additional studies of genotype (or haplotype) and coronary events would help clarify whether or not the link between CRP and coronary events in observational studies is causal.

Estrogen receptor alpha gene variation is associated with risk of myocardial infarction in more than seven thousand men from five cohorts.

Understanding the mechanisms by which estrogens affect cardiovascular disease risk, including the role of variation in the gene for estrogen receptor alpha (ESR1), may be key to new treatment strategies. We investigated whether the CC genotype at ESR1 c.454-397T>C is associated with increased risk among men. Study of more than 7000 whites in 5 cohorts from 4 countries provided evidence that genotype CC, present in roughly 20% of individuals, is a risk factor for nonfatal acute myocardial infarction (odds ratio=1.44; P<0.0001), after adjustment for established cardiovascular risk factors. After exclusion of younger subjects from 2 cohorts, because of age interaction, the odds ratio increased (to 1.63).

Common variants in the TCF7L2 gene and predisposition to type 2 diabetes in UK European Whites, Indian Asians and Afro-Caribbean men and women.

Common variants of TCF7L2, encoding a beta-cell-expressed transcription factor, are strongly associated with increased risk of type 2 diabetes (T2D). We examined this association using both prospective and case-control designs. A total of 2,676 healthy European white middle-aged men from the prospective NPHSII (158 developed T2D over 15 years surveillance) were genotyped for two intronic SNPs [rs 7903146 (IVS3C>T) and rs12255372 (IVS4G>T)] which showed strong linkage disequilibrium (D' = 0.88, p<0.001; R(2)=0.76, p<0.001). The IVS5T allele frequency was 0.28 (95% CI 0.27-0.29) and 0.33 (0.28-0.39) in healthy and T2D, respectively (p=0.04). Compared to CC men, CT and TT men had an adjusted [for age, body mass index, systolic blood pressure, triglyceride and C-reactive protein levels] hazard ratio for T2D of 1.65 (1.13-2.41) and 1.87 (0.99-3.53), respectively, p<0.01. The population attributable fraction for diabetes risk was 17%. In 1459, European white T2D men and women (60% male), T allele frequency was 0.36 (0.34-0.38), and compared to NPHSII healthy men the OR for T2D for the CT and TT subjects was 1.43 (1.24-1.65) and 2.11 (1.69-2.63), respectively p=<0.0001. A similar effect was observed in 919 T2D Indian Asians [OR=1.50 (1.14-1.99) and 1.64 (1.03-2.63) p=0.003] and 385 Afro-Caribbean subjects [OR=1.25 (0.90-1.75) and 1.32 (0.74-2.33) p=0.17] compared to non-diabetic ethnically matched subjects from South London. Weaker associations were found for the IVS4G>T in all studies. Linkage disequilibrium between the two SNPs was high in Indian Asians (D'=0.94), but much weaker in Afro-Caribbeans (D'=0.17) and haplotype frequencies differed markedly in this group. These results extend previous observations to other ethnic groups, and strongly confirm that TCF7L2 genotype is a major risk factor for development of T2D.

A common variant in the glutathione S transferase gene is associated with elevated markers of inflammation and lipid peroxidation in subjects with diabetes mellitus.

INTRODUCTION: Glutathione S transferases (GST) are enzymes responsible for the metabolism of numerous xenobiotics and play a major cellular antioxidant role. Our aim was firstly, to examine the association between the GST M1/GST mu-1 (GSTM1) and GST T1/GST theta-1 (GSTT1) gene variants with markers of oxidative stress and inflammation in diabetic patients, and secondly to examine the association and potential interaction between these variants and cigarette smoking. METHODS: Seven hundred and seventy-three Caucasian subjects with diabetes and 2592 Caucasian non-diabetic subjects were successfully genotyped. Plasma total antioxidant status, C-reactive protein (CRP), oxidized-LDL (Ox-LDL) and LDL-mean/peak particle diameter were recorded in the diabetes sample. RESULTS: No association was seen between genotype and cardiovascular disease (CVD) risk. In the diabetic subjects, GSTT1-1 compared to GSTT1-0 subjects had significantly higher CRP (p=0.001), Ox-LDL (p=0.004) and smaller LDL particles (p=0.01). In subjects without CVD, there was a significant interaction between the GSTT1-1 variant and smoking in determining Ox-LDL (p=0.04). Furthermore, CVD risk was higher in smokers compared to non-smokers with GSTT1-1. No significant associations were observed by GSTM1. Within the non-diabetic sample, no association was observed between genotype and prospective coronary heart disease (CHD) risk. Of note, the frequency of the GSTT1-1 variant was significantly lower in the diabetes subjects compared to the non-diabetic sample (p=0.01). CONCLUSIONS: This study demonstrates an association between the GSTT1-1 variant and markers of inflammation and lipid peroxidation. Furthermore this variant interacts with smoking to increase lipid peroxidation.

Increased plasma markers of oxidative stress are associated with coronary heart disease in males with diabetes mellitus and with 10-year risk in a prospective sample of males.

BACKGROUND: Increased oxidative stress is associated with coronary heart disease (CHD). We examined the association between plasma markers of oxidative stress and CHD in a cross-sectional sample of patients with diabetes and prospective CHD risk in a sample of men predominantly without diabetes. METHODS: Plasma total antioxidant status (TAOS) and the ratio of oxidized LDL (Ox-LDL) to LDL-cholesterol (LDL-C) were determined in a cross-section of 761 Caucasian individuals with diabetes (UDACS study). Plasma TAOS was also determined in 310 baseline samples from a 10-year prospective cohort of 3012 healthy males (NPHSII). RESULTS: Within UDACS, males with CHD had lower mean (SD) plasma TAOS [no CHD, 43.4 (13.2)%; CHD, 40.3 (13.8)%; P = 0.04]. The prevalence of CHD was higher in the lowest compared with the upper quartiles (32.7% vs 19.7%; P = 0.004). We observed a significant association between plasma Ox-LDL:LDL-C and CHD status [no CHD vs CHD, 16.9 (3.1) vs 19.3 (5.0) units/mmol; P = 0.04], with the prevalence of CHD being higher among men in the upper compared with lower quartiles (18.4% vs 35.1%; P = 0.003). No association was observed in females. In NPHSII, TAOS was lower in those who developed CHD [35.1 (8.0)% vs 37.1 (7.9)%; P = 0.04]. The odds ratio for CHD in the lowest compared with the upper quartile was 1.91 (95% confidence interval, 0.99-3.70; P = 0.04). This remained unchanged after adjustment for classic risk factors. CONCLUSIONS: A cross-sectional and prospective association exists between baseline plasma measures of oxidative stress and CHD risk. The association with prospective CHD risk remained after adjustment for "traditional" risk factors, implying an independent role for oxidative stress in CHD risk.

A study of TH01 and IGF2-INS-TH haplotypes in relation to smoking initiation in three independent surveys.

OBJECTIVES: Recent studies suggest an association between a microsatellite locus (TH01) located in intron 1 of the tyrosine hydroxylase gene (TH) and nicotine dependence. We aimed here to study whether both TH01 and haplotypes of the wider IGF2-INS-TH region influence initiation of regular smoking in current smokers. METHODS: A total of 3637 individuals from three independent studies (two of adults and one of adolescents) were analysed in relation to the age of first regular smoking (AFRS). Haplotypes and genotypes were obtained for the polymorphisms TH01, IGF2 ApaI, INS HphI and DRD4 VNTR (48 bp)n. Association between IGF2-INS-TH haplotypes and AFRS was tested by a regression model. A genotype-based genetic model assuming additivity was followed in order to estimate the effect of individual loci. RESULTS: Overall, no significant associations were found after correcting for multiple tests. However, an IGF2-INS-TH haplotype (*5) was found to be nominally associated with AFRS at younger ages in adult smokers. Analyses of individual loci points to TH01 as a possible candidate influencing initiation of regular smoking. An AFRS-lowering trend nominally associated with allele 9 in a dosage-dependent manner was identified in both adult cohorts. TH01 did not show association or trend with age of initiation (first puff) either in adolescents or in the adolescents smoking regularly at age 18. CONCLUSION: This study adds to the genetic evaluation of the associations of TH01 with smoking predisposition. Differences between historical and prospective surveys, different biological pathways and possible functional roles of this microsatellite in smoking initiation are discussed.

Cardiorespiratory fitness, all-cause mortality, and risk of cardiovascular disease in Trinidadian men--the St James survey

BACKGROUND: This study examined whether cardiorespiratory fitness is a risk factor for cardiovascular disease, myocardial infarction, and all-cause mortality in a low- to middle-income Trinidadian community of African, South Asian Indian, and European origin. Those of Indian descent have a distinctively high rate of myocardial infarction. METHODS: The St James Study is a prospective total community survey located in Port-of-Spain, Trinidad, West Indies. A random sample of 626 men aged 35-69 years, without angina of effort, previous myocardial infarction, partial or complete atrio-ventricular conduction defect, complete heart block, or exercise-induced asthma, was used for the assessment of cardiorespiratory fitness by cycle ergometry. Surveillance for morbidity and mortality was maintained for an average of 7.3 years. RESULTS: When the subjects were grouped into those with an age- and fat-free mass-adjusted peak oxygen uptake above and below the mean of 60.4 mmol/min (1.34 l/min), the hazard ratios (below/above) (95% confidence interval) for all-cause mortality, cardiovascular disease incidence, and incidence of myocardial infarction, after allowance for conventional cardiovascular risk factors, were 2.08 (1.23-3.52), 2.13 (1.22-3.69), and 2.36 (0.84-6.67), respectively. For those unable to achieve a level of work requiring an oxygen uptake of 67 mmol/min (1.5 l/min) during progressive exercise, the respective hazard ratios were 3.49 (1.57-7.76), 2.29 (1.21-4.33), and 5.45 (1.22-24.34). Indian ethnicity remained a predictor of myocardial infarction after allowance for cardiorespiratory performance. CONCLUSION: Low cardiorespiratory fitness is a risk factor for cardiovascular disease morbidity and mortality in the low- to middle-income developing community of Trinidad.