Risk factor clustering in the insulin resistance syndrome and its relationship to cardiovascular disease in postmenopausal white, black, hispanic, and Asian/Pacific Islander women

Association of remnant cholesterol with chronic kidney disease in middle-aged and elderly Chinese: a population-based study

AIMS

Limited data regarding the association between remnant cholesterol (RC) and chronic kidney disease (CKD), largely based on an estimated glomerular filtration rate (eGFR) of < 60 mL/min/1.73 m² (low eGFR), have yielded inconsistent results, and no report has demonstrated the relationship of RC with CKD [defined as low eGFR and/or albuminuria (defined as urinary albumin-to-creatinine ratio (ACR) ≥ 30 mg/g)] in Chinese general middle-aged and elderly population. Hence, we aimed to investigate the association between RC and CKD in such population.

METHODS

In total, 7356 Chinese participants aged ≥ 40 years were recruited from five regional communities in Luzhou city between May 2011 and December 2011. Fasting RC was calculated from the lipid profile measured by standard laboratory procedures. Multivariate logistic regression models were used to evaluate the possible association between RC and CKD.

RESULTS

Participants in the highest quartile of RC had higher body mass index, systolic and diastolic blood pressure, total cholesterol, triglyceride, low-density lipoprotein cholesterol (LDL-C), fasting and 2-h postload blood glucose, glycated hemoglobin A1C, prevalence of prediabetes, type 2 diabetes mellitus (T2DM), hypertension, CKD, albuminuria, low eGFR, and lower high-density lipoprotein cholesterol (HDL-C) and eGFR compared with those in the lowest quartile (all P for trend < 0.01). Multivariate logistic regression analysis demonstrated that the risk of CKD gradually increased across RC quartiles (P for trend < 0.01), and participants in the highest quartile of RC were at a significantly increased risk of prevalent CKD compared to those in the lowest quartile in total subjects (odds rate: 1.344, 95% confidence intervals 1.097-1.648, P < 0.01). In subgroup analysis, significant relation between RC level and increased risk of prevalent CKD was detected in women, subjects with overweight/obesity, non-prediabetes, hypertension, normal HDL-C, appropriate and high LDL-C, and without cardiovascular disease (CVD) events after multiple adjustments.

CONCLUSIONS

Higher RC is independently associated with increased risk of prevalent CKD, and RC might serve as a new risk biomarker for CKD in a general middle-aged and elderly Chinese population, especially in women, subjects with overweight/obesity, non-prediabetes, hypertension, normal HDL-C, appropriate and high LDL-C, and without CVD events.

Association Between Hypertriglyceridemic Waist Phenotype and Increased Urinary Albumin-Creatinine Ratio in Chinese Adults: The REACTION Study

PURPOSE

The hypertriglyceridemic waist (HTGW) phenotype can predict cardiovascular disease (CVD) risk. Additionally, strong evidence indicates that elevated urinary albumin-creatinine ratio (UACR) is associated with increased prevalence of CVD. However, few studies have explored the association between the HTGW phenotype and UACR.

PATIENTS AND METHODS

In this cross-sectional descriptive study, a total of 40,674 subjects (28,562 women and 12,112 men older than 40 years) were recruited from seven different geographic regional centres. The HTGW phenotype was defined as increased triglyceride levels (triglyceride ≥ 1.5 mmol/L for female and ≥2.0 mmol/L for male) and waist circumference (WC; WC ≥ 85 for female and WC ≥ 90 cm for male). Logistic regression analyses were performed to assess the relationship between UACR and the HTGW phenotype.

RESULTS

Subjects with the HTGW phenotype showed a more significant trend towards increased excretion of UACR [among all subjects, odds ratio (OR) = 1.303, 95% CI: 1.132-1.499, P < 0.001; among men, OR = 1.406, 95% CI: 1.057-1.870, P = 0.019; among women, OR = 1.268, 95% CI: 1.074-1.496, P = 0.005]. Furthermore, the stratified analysis showed that the OR for high-risk significantly increased in individuals in the HTGW group aged below 65 years, with 5.6 ≤ fasting blood glucose < 7.0 or 7.8 ≤ post-load blood glucose <11.1 mmol/L, 120 ≤ systolic blood pressure < 140 or 80 ≤ diastolic blood pressure < 90, 24 ≤ body mass index < 28 kg/m², and estimated globular filtration rate > 90 mL/min per 1.73 m².

CONCLUSION

This study has advanced the understanding of visceral obesity and our results supported the fact that the HTGW phenotype is associated with elevated UACR excretion among general Chinese adults.

Effects of high-intensity interval training on cardiometabolic risk in overweight and obese African-American women: a pilot study

OBJECTIVE

Little is known about high-intensity interval training (HIIT) in African-American (AA) women. The purpose of this pilot study was to evaluate the effects of HIIT and steady-state (SS) exercise on cardiometabolic risk factors in young AA women.

DESIGN

A 16-week exercise intervention was conducted 3x/week. Twenty-seven AA women were randomized to SS (n = 11; 32 continuous minutes of treadmill walking at 60-70% of maximum heart rate (HR_max)), or HIIT (n = 16; 32 min of treadmill HIIT alternating 3 min at 60-70% of HR_max with 1 min at 80-90% of HR_max). Two-way repeated measures ANOVA with intention-to-treat analysis was used to identify changes between groups. Significance was accepted at P ≤ 0.05.

RESULTS

Of the 27 women who entered the study (age: 30.5 ± 6.8 years; BMI: 35.1 ± 5.1 kg/m²; 5274 ± 1646 baseline steps/day), 14 completed the intervention. HIIT significantly decreased waist circumference (107.0 ± 11.3 to 105.1 ± 11.9 cm) compared to SS, which showed no change. There was a significant time effect for steps where HIIT increased steps/day (5334 ± 1586 to 7604 ± 1817 steps/day), and SS had no change. There were no significant changes in either group for any other measurements.

CONCLUSION

HIIT was more effective at reducing waist circumference and increasing daily steps/day than SS treadmill exercise over 16 weeks. Further research in a larger sample is indicated to evaluate the effects of each protocol on cardiometabolic risk factors.

Interethnic Differences in Serum Lipids and Implications for Cardiometabolic Disease Risk in African Ancestry Populations

African Americans generally have a healthier lipid profile (lower triglycerides and higher high-density lipoprotein cholesterol concentration) compared with those of other ethnicities. Paradoxically, African Americans do not experience a decreased risk of the cardiometabolic diseases that serum lipids are expected to predict. This review explores this mismatch between biomarker and disease among African ancestry individuals by investigating the presence of interethnic differences in the biological relationships underlying the serum lipids-disease association. This review also discusses the physiologic and genomic factors underlying these interethnic differences. Additionally, because of the importance of serum lipids in assessing disease risk, interethnic differences in serum lipids have implications for identifying African ancestry individuals at risk of cardiometabolic disease. Where possible, data from Africa is included, to further elucidate these ancestral differences in the context of a different environmental background.

Circulating leptin and adiponectin are associated with insulin resistance in healthy postmenopausal women with hot flashes

Introduction

Hot flashes have been postulated to be linked to the development of metabolic disorders. This study aimed to evaluate the relationship between hot flashes, adipocyte-derived hormones, and insulin resistance in healthy, non-obese postmenopausal women.

Participants and design

In this cross-sectional study, a total of 151 women aged 45–60 years were stratified into one of three groups according to hot-flash status over the past three months: never experienced hot flashes (Group N), mild-to-moderate hot flashes (Group M), and severe hot flashes (Group S). Variables measured in this study included clinical parameters, hot flash experience, fasting levels of circulating glucose, lipid profiles, plasma insulin, and adipocyte-derived hormones. Multiple linear regression analysis was used to evaluate the associations of hot flashes with adipocyte-derived hormones, and with insulin resistance.

Settings

The study was performed in a hospital medical center.

Results

The mean (standard deviation) of body-mass index was 22.8(2.7) for Group N, 22.6(2.6) for Group M, and 23.5(2.4) for Group S, respectively. Women in Group S displayed statistically significantly higher levels of leptin, fasting glucose, and insulin, and lower levels of adiponectin than those in Groups M and N. Multivariate linear regression analysis revealed that hot-flash severity was significantly associated with higher leptin levels, lower adiponectin levels, and higher leptin-to-adiponectin ratio. Univariate linear regression analysis revealed that hot-flash severity was strongly associated with a higher HOMA-IR index (% difference, 58.03%; 95% confidence interval, 31.00–90.64; p < 0.001). The association between hot flashes and HOMA-IR index was attenuated after adjusting for leptin or adiponectin and was no longer significant after simultaneously adjusting for leptin and adiponectin.

Conclusion

The present study provides evidence that hot flashes are associated with insulin resistance in postmenopausal women. It further suggests that hot flash association with insulin resistance is dependent on the combination of leptin and adiponectin variables.

Genetic polymorphism of estrogen receptor alpha gene in Egyptian women with type II diabetes mellitus

Estrogen might play an important role in type 2 diabetes mellitus pathogenesis. A number of polymorphisms have been reported in the estrogen receptor alpha gene including the XbaI and PvuII restriction enzyme polymorphisms. The aim of this study was to determine if ESRα gene polymorphisms are associated with type 2 diabetes mellitus and correlated with lipid profile. Ninety diabetic Egyptian patients were compared with forty healthy controls. ESRα genotyping of PvuII and XbaI was performed using restriction fragment length polymorphism analysis. Our study showed that there is more significant difference in the frequency of C and G polymorphic allele between patients and control groups in PvuII and XbaI respectively. Also carriers of minor C and G alleles of PvuII and XbaI gene polymorphisms were associated with increased fasting blood glucose and disturbance in lipid profile as there is an increase in total cholesterol, triglycerides and Low density lipoprotein. So findings of present study suggest the possibility that PvuII and XbaI polymorphisms in ERα are related to T2DM and with increased serum lipids among Egyptian population.

Race and ethnicity, obesity, metabolic health, and risk of cardiovascular disease in postmenopausal women

Background

It is unclear whether obesity unaccompanied by metabolic abnormalities is associated with increased cardiovascular disease risk across racial and ethnic subgroups.

Methods and Results

We identified 14 364 postmenopausal women from the Women's Health Initiative who had data on fasting serum lipids and serum glucose and no history of cardiovascular disease or diabetes at baseline. We categorized women by body mass index (in kg/m²) as normal weight (body mass index 18.5 to <25), overweight (body mass index 25 to <30), or obese (body mass index ≥30) and by metabolic health, defined first as the metabolic syndrome (metabolically unhealthy: ≥3 metabolic abnormalities) and second as the number of metabolic abnormalities. We used Cox proportional hazards regression to assess associations between baseline characteristics and cardiovascular risk. Over 13 years of follow-up, 1101 women had a first cardiovascular disease event (coronary heart disease or ischemic stroke). Among black women without metabolic syndrome, overweight women had higher adjusted cardiovascular risk than normal weight women (hazard ratio [HR] 1.49), whereas among white women without metabolic syndrome, overweight women had similar risk to normal weight women (HR 0.92, interaction P=0.05). Obese black women without metabolic syndrome had higher adjusted risk (HR 1.95) than obese white women (HR 1.07; interaction P=0.02). Among women with only 2 metabolic abnormalities, cardiovascular risk was increased in black women who were overweight (HR 1.77) or obese (HR 2.17) but not in white women who were overweight (HR 0.98) or obese (HR 1.06). Overweight and obese women with ≤1 metabolic abnormality did not have increased cardiovascular risk, regardless of race or ethnicity.

Conclusions

Metabolic abnormalities appeared to convey more cardiovascular risk among black women.

Comparison of predictive value of cardiometabolic indices for subclinical atherosclerosis in Chinese adults

Objectives

Metabolic disturbances are well-known risk factors for atherosclerosis, but it remains unclear which cardiometabolic components are the predominant determinants. This study aimed to compare and identify the key determinants of carotid atherosclerosis in asymptomatic middle-aged and elderly Chinese.

Methods

A community-based cross-sectional study including 3,162 apparently healthy residents aged 37–75 years was performed from July 2008 to June 2010 in Guangzhou, China. Carotid artery intima-media thickness (IMT) was assessed by B-mode ultrasound, and increased IMT was defined as IMT>1.00 mm. Obesity indices, blood pressure, fasting blood lipids, glucose and uric acid levels were determined. Principal components factor analysis was used to extract common factors underlying 11 metabolic factors.

Results

Four common factors, defined as “adiposity,” “blood lipids,” “triglycerides/uric acid (TG/UA)” (in men) or “triglycerides/uric acid/glucose (TG/UA/Glu)” (in women), and “blood pressure,” were retained for both sexes. After adjustment for potential covariates, the “adiposity” factor showed the strongest positive association with increased IMT in men. Comparing the extreme quartiles, ORs (95% CI) of increased IMT were 4.64 (2.04–10.59) at the CCA and 2.37 (1.54–3.64) at the BIF), followed by “blood pressure”, the corresponding OR (95% CI) was 2.85 (1.37–5.90) at the CCA. Whereas, the four common factors showed comparable and weak relationship with increased IMTs, the ORs for quartile 4 vs. quartile 1 varied from 0.89 to 3.59 in women.

Conclusions

Among the metabolic factors, “adiposity” and “blood pressure” play predominant roles in the presence of carotid atherosclerosis in men, but no key factor is identified in women.

Dietary medium-chain triglyceride supplementation has no effect on apolipoprotein B-48 and apolipoprotein B-100 kinetics in insulin-resistant men

BACKGROUND

Medium-chain triglyceride (MCT) supplements are used by clinicians to treat patients with severe hypertriglyceridemia who are at risk of pancreatitis. However, the potential mechanisms underlying the effects of MCT on triglyceride-rich lipoprotein (TRL) metabolism have not yet been thoroughly examined in humans.

OBJECTIVE

This double-blind randomized crossover study compared the impact of 4 wk of supplementation with 20 g MCT oil/d or 20 g corn oil/d on the kinetics of apolipoprotein (apo) B-48-containing TRLs and apo B-100-containing very-low-density lipoprotein (VLDL), as well as on the expression of key intestinal genes involved in lipid metabolism in 28 obese, insulin-resistant men.

DESIGN

The in vivo kinetics of TRL apo B-48 and VLDL apo B-100 were assessed by using a primed-constant infusion of l-[5,5,5-d3]leucine for 12 h in the fed state. Real-time polymerase chain reaction quantification was performed on duodenal biopsy samples taken at the end of each phase of supplementation.

RESULTS

Compared with corn oil, MCT supplements had no significant effect on plasma lipoprotein profile or TRL apo B-48 and VLDL apo B-100 kinetics. Positive correlations were observed between the intestinal expression of several key genes involved in lipoprotein metabolism in a subgroup of participants (n = 16) after MCT supplementation. However, there was no difference between MCT and the corn oil control supplement in the intestinal messenger RNA expression levels of these key genes.

CONCLUSION

These data indicate that short-term supplementation with MCT has a neutral effect on TRL apo B-48 and VLDL apo B-100 kinetics and on the intestinal expression of genes involved in lipid and fatty acid metabolism in men with insulin resistance. This trial was registered at www.clinicaltrials.gov as NCT01806142.

Genetics of coronary artery calcification among African Americans, a meta-analysis

Background

Coronary heart disease (CHD) is the major cause of death in the United States. Coronary artery calcification (CAC) scores are independent predictors of CHD. African Americans (AA) have higher rates of CHD but are less well-studied in genomic studies. We assembled the largest AA data resource currently available with measured CAC to identify associated genetic variants.

Methods

We analyzed log transformed CAC quantity (ln(CAC + 1)), for association with ~2.5 million single nucleotide polymorphisms (SNPs) and performed an inverse-variance weighted meta-analysis on results for 5,823 AA from 8 studies. Heritability was calculated using family studies. The most significant SNPs among AAs were evaluated in European Ancestry (EA) CAC data; conversely, the significance of published SNPs for CAC/CHD in EA was queried within our AA meta-analysis.

Results

Heritability of CAC was lower in AA (~30%) than previously reported for EA (~50%). No SNP reached genome wide significance (p < 5E-08). Of 67 SNPs with p < 1E-05 in AA there was no evidence of association in EA CAC data. Four SNPs in regions previously implicated in CAC/CHD (at 9p21 and PHACTR1) in EA reached nominal significance for CAC in AA, with concordant direction. Among AA, rs16905644 (p = 4.08E-05) had the strongest association in the 9p21 region.

Conclusions

While we observed substantial heritability for CAC in AA, we failed to identify loci for CAC at genome-wide significant levels despite having adequate power to detect alleles with moderate to large effects. Although suggestive signals in AA were apparent at 9p21 and additional CAC and CAD EA loci, overall the data suggest that even larger samples and an ethnic specific focus will be required for GWAS discoveries for CAC in AA populations.

Clustering of cardiac risk factors associated with the metabolic syndrome and associations with psychosocial distress in a young Asian Indian population

The metabolic syndrome is a precursor for coronary heart disease. However, its pathophysiology is not clear, its phenotypic expression may vary by region; also, the phenotypic manifestation may be exacerbated by psychosocial distress and family history. The purpose of the current study was to assess the factor structure of the metabolic syndrome in young urban Asian Indians. Asian Indian youth (N = 112) were evaluated for body mass index (BMI), waist-hip ratio, blood pressure (systolic: SBP; diastolic: DBP), blood sugar, triglycerides, cholesterol, insulin, psychosocial distress and family health history. Factor analyses were computed on components of the metabolic syndrome. Three factors were identified for the entire sample: hemodynamic-obesity (SBP, DBP, waist-hip ratio), Lipid (cholesterol, triglyceride), and insulin-obesity (blood sugar, BMI, insulin). Similar to previous research with this population, three distinct factors with no overlap were identified. Factors did not correlate with psychosocial distress or family history. Lack of correlation with family history and psychosocial distress may be a function of the young age and demographics of the sample.

Estrogen receptor alpha gene polymorphisms are associated with type 2 diabetes and fasting glucose in male subjects

The PvuII and XbaI polymorphisms of the estrogen receptor α (ER1) gene have been variably associated with type 2 diabetes (T2D) in several populations. However, this association has not been studied in Iranian subjects and we hypothesized that the ER1 variants might be associated with T2D and related metabolic traits in this population. The PvuII and XbaI genotypes were determined by PCR-RFLP in 377 normoglycemic controls and 155 T2D patients. Bonferroni correction was applied for the correction of multiple testing. No significant association was found between the allele and genotype frequencies of PvuII and XbaI variants with T2D in females. In a dominant model (PP vs. Pp+pp), the frequency of the Pp+pp genotype was higher in normoglycemic subjects compared to T2D patients [85.5% vs. 66.7%, OR 0.22 (0.08-0.55), P=0.001]. Four possible haplotypes were observed in the population, whereas haplotype TA had a higher frequency in male T2D subjects than the controls. Furthermore, non-diabetic male subjects carrying the genotype of PP had a higher fasting glucose levels than the individuals with the genotype of Pp+pp (P=0.013). Multivariate logistic regression analysis showed that PvuII polymorphism was the independent determinants of T2D in males [OR 4.37 (1.61-11.86), P=0.004]. No association was found between the XbaI polymorphism and diabetes in male group. Our results suggest that the ER1 polymorphisms might associate with T2D and fasting glucose among Iranian male subjects.

Prevalence of metabolic syndrome among human immunodeficiency virus-infected subjects is widely influenced by the diagnostic criteria

BACKGROUND

The aim of this study was to compare the prevalence of metabolic syndrome in human immunodeficiency virus (HIV)-infected patients treated with highly active antiretroviral therapy (HAART), using the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III), European Group for the Study of Insulin Resistance (EGIR), and International Diabetes Federation (IDF) definitions.

METHODS

A cross-sectional study was carried out with 159 consecutive adult HIV-infected subjects (120 males and 39 females) under HAART. Anthropometric and laboratory parameters were measured by standard methods. Hyperinsulinemia was defined by a fasting concentration >75th percentile of values obtained in healthy individuals (107.5 pmol/L).

RESULTS

The prevalence of ATP III-defined metabolic syndrome was 10.1%; it was 28.3% according to EGIR criteria and 15.1% using the IDF definition. The concordance between the definitions was low (kappa coefficient ranging between 0.134 and 0.296). All subjects with EGIR-defined metabolic syndrome had hyperinsulinemia, but only 50% of those with ATP III-defined metabolic syndrome and 62.5% in the IDF metabolic syndrome population had hyperinsulinemia.

CONCLUSIONS

The inclusion of hyperinsulinemia as a criterion in the EGIR metabolic syndrome definition made it more discriminative than the ATP III definition, both in men and women, and than the IDF definition in men to identify metabolic syndrome in HIV-infected subjects under HAART.

The association between the rs2234693 and rs9340799 estrogen receptor alpha gene polymorphisms and risk factors for cardiovascular disease: a review

Although estrogen is primarily thought of as the hormone involved in female reproduction, it also plays a role in many additional physiological and pathological processes. Recent studies have demonstrated an association between estrogen and clustered risk factors for cardiovascular disease (CVD), such as lipid and glucose metabolism and obesity-related phenotypes, as well as occurrence and severity of CVD. Evidence suggesting a genetic basis for this link is accumulating. Several polymorphisms of the estrogen receptor (ER) alpha (ESR1) gene exist that may influence the impact of estrogen, leading to clinically relevant phenotypes. Based on the relationship ERS1 seems to exhibit with CVD risk factors, these polymorphisms may play a role in the mediation of vasoprotective effects, modulation of cardiovascular physiology, and development of risk factors for CVD. The two most frequently studied polymorphisms located in ESR1 are often identified by their restriction endonucleases Pvull (rs2234693) and Xbal (rs9340799). ln this review, we have evaluated and summarized the results of studies involving rs2234693 and rs9340799 and clustered risk factors accompanying development of CVD. Despite inconsistent findings, together these studies provide some support for a relationship between polymorphisms in ESR1 and risk factors for CVD. These summarized findings do not yet support inclusion of ESR1 genotypes in genetic testing algorithms for predisposition to CVD, but they do indicate that further investigation into the potential connection between ESR1 and risk factors for CVD is warranted.

Usefulness of apolipoprotein B/apolipoprotein A-I ratio to predict coronary artery disease independent of the metabolic syndrome in African Americans

Studies have demonstrated that the apolipoprotein B/apolipoprotein A-I (apoB/apoA-I) ratio predicts cardiovascular risk better than any of the cholesterol indexes. A number of factors that define the metabolic syndrome (MS) differ across African-American and European-American ethnicities. We assessed the relation of the apoB/apoA-I ratio to MS and coronary artery disease (CAD) in 224 African Americans and 304 European Americans. The MS was defined using the revised National Cholesterol Education Program Adult Treatment Panel III criteria, and CAD was assessed as ≥50% stenosis or a continuous cardiovascular score (0 to 75). The European Americans had a greater apoB/apoA-I ratio than the African Americans (1.15 vs 1.07, p = 0.008). The apoB/apoA-I ratio was associated with presence of the MS in both European Americans (odds ratio 5.9, 95% confidence interval 2.53 to 13.57, p <0.001) and African Americans (odds ratio 8.3, 95% confidence interval 3.52 to 19.25, p <0.001) and was greater in subjects with the MS than in those without the MS (1.21 vs 1.04, p <0.001, for European Americans and 1.20 vs 0.94, p <0.001, for African Americans). A stepwise increase was seen in the prevalence of the MS across the apoB/apoA-I ratio tertiles in both ethnic groups (chi-square = 13.1, p <0.001, for European Americans and chi-square = 19.6, p <0.001, for African Americans). On multiple regression analyses, the apoB/apoA-I ratio independently predicted CAD in African Americans (β = 0.242, p = 0.011). The cardiovascular score was significantly increased across the apoB/apoA-I ratio tertiles in the European-American subjects with the MS (p = 0.001). However, this association was seen in the African-American subjects without the MS (p = 0.023). In conclusion, the apoB/apoA-I ratio differed across ethnicities and was associated with presence of the MS in both groups. Among African Americans, an elevated apoB/apoA-I ratio independently predicted a greater risk of CAD.

Cynicism: Incident diabetes and worsening of metabolic syndrome in postmenopausal women

OBJECTIVE

To determine if self-reported cynical hostility predicted incident diabetes or increase in number of symptoms associated with metabolic syndrome in postmenopausal women.

DESIGN

Prospective study of a subsample of women (n = 3,658) participating in the Women's Health Initiative Clinical Trial.

METHODS

Subjects: Postmenopausal women aged 50 to 79 years at baseline who were enrolled in the Women's Health Initiative Dietary Modification Trial, Hormone Trial or both. Measures: The Cynicism subscale of the Cook-Medley Hostility Questionnaire was used to assess cynical hostility at baseline. Incident diabetes was ascertained by self-report of treatment with insulin or oral hypoglycemic medication at one year. Metabolic syndrome was defined based on number of Adult Treatment Panel (ATP) III criteria met at one year. Statistical Analysis: The relationship between baseline cynical hostility and incident diabetes and worsening of metabolic syndrome was assessed from baseline to one year using multivariable Cox proportional hazards models and multivariable logistic regression models, respectively.

RESULTS

Incident diabetes was 36% higher among women in the upper tertile for baseline cynical hostility compared to the lowest tertile (p-trend = 0.05). The odds of a worsening of metabolic syndrome was 27% greater in the highest cynical hostility tertile compared to the lowest tertile (p-trend = 0.04).

CONCLUSIONS

Cynical hostility may increase the risk for developing diabetes and worsening of the metabolic syndrome in postmenopausal women.

Association analysis of 33 lipoprotein candidate genes in multi-generational families of African ancestry

African ancestry individuals have a more favorable lipoprotein profile than Caucasians, although the mechanisms for these differences remain unclear. We measured fasting serum lipoproteins and genotyped 768 tagging or potentially functional single nucleotide polymorphisms (SNPs) across 33 candidate gene regions in 401 Afro-Caribbeans older than 18 years belonging to 7 multi-generational pedigrees (mean family size 51, range 21-113, 3,426 relative pairs). All lipoproteins were significantly heritable (P<0.05). Gender-specific analysis showed that heritability for triglycerides was much higher (P<0.01) in women than in men (women, 0.62+/-0.18, P<0.01; men, 0.13+/-0.17, P>0.10), but the heritability for LDL cholesterol (LDL-C) was higher (P<0.05) in men than in women (men, 0.79+/-0.21, P<0.01; women, 0.39+/-0.12, P<0.01). The top 14 SNPs that passed the false discovery rate threshold in the families were then tested for replication in an independent population-based sample of 1,750 Afro-Caribbean men aged 40+ years. Our results revealed significant associations for three SNPs in two genes (rs5929 and rs6511720 in LDLR and rs7517090 in PCSK9) and LDL-C in both the family study and in the replication study. Our findings suggest that LDLR and PCSK9 variants may contribute to a variation in LDL-C among African ancestry individuals. Future sequencing and functional studies of these loci may advance our understanding of genetic factors contributing to LDL-C in African ancestry populations.

Factor analysis of risk variables associated with metabolic syndrome in adult Asian Indians

BACKGROUND

Several studies hinted about the clustering of risk variables of the metabolic syndrome (MS) and suggested that the underlying genetic polymorphisms could be responsible for the increasing incidence of coronary heart disease (CHD) in people of Indian origin. Therefore, identification of the components of the MS along with the genetic factors could be one of the aspects to make an attempt to prevent the increasing incidence of CHD.

MATERIALS AND METHODS

Principal component factor analysis (PCFA) was undertaken to identify the components or factors of the MS among the adult (≥30 years) Asian Indians living in and around Calcutta, India. The study comprised 350 adult Asian Indians. Anthropometric measurements were taken, and lipid profiles, blood pressure and fasting blood glucose were measured for each participant. Two genetic polymorphisms, namely, angiotensin converting enzyme (ACE) gene polymorphism (insertion/deletion [I/D]) or ACE (I/D) and apolipoproteinE (Hha I) were also studied.

RESULTS

PCFA revealed 3 factors that cumulatively explained 65.39% of the observed variance of the MS by measured variables. The 3 factors identified were lipids and lipoprotein (Factor 1), centripetal fat and blood pressure (Factor 2), and ACE (I/D) polymorphism with blood pressure (Factor 3). Moreover, the first 2 factors, that is, lipids, lipoprotein, centripetal fat, and blood pressures cumulatively explained ~46% (45.94%) of the observed variance of MS in this population.

CONCLUSIONS

Since more than 1 factor was identified for the MS phenotype, more than 1 physiogenetic mechanism could be accounted for MS in the Asian Indian population.

Evaluation of the American Heart Association cardiovascular disease prevention guideline for women

BACKGROUND

The 2007 update to the American Heart Association (AHA) guidelines for cardiovascular disease prevention in women recommend a simplified approach to risk stratification. We assigned Women's Health Initiative participants to risk categories as described in the guideline and evaluated clinical event rates within and between strata.

METHODS AND RESULTS

The Women's Health Initiative enrolled 161 808 women ages 50 to 79 years and followed them prospectively for 7.8 years (mean). Applying the 2007 AHA guideline categories, 11% of women were high risk, 72% at-risk, and 4% at optimal risk; 13% of women did not fall into any category, that is, lacked risk factors but did not adhere to a healthy lifestyle (moderate intensity exercise for 30 minute most days and <7% of calories from saturated fat). Among high risk, at-risk, and optimal risk women, rates of myocardial infarction/coronary death were 12.5%, 3.1%, and 1.1% per 10 years (P for trend <0.0001); the event rate was 1.3% among women who could not be categorized. We observed a graded relationship between risk category and cardiovascular event rates for white, black, Hispanic, and Asian women, although event rates differed among ethnic groups (P for interaction=0.002). The AHA guideline predicted coronary events with accuracy similar to current Framingham risk categories (area under receiver operating characteristic curve for Framingham risk, 0.665; for AHA risk, 0.664; P=0.94) but less well than proposed Framingham 10-year risk categories of <5%, 5% to 20%, and >20% (area under receiver operating characteristic curve for Framingham risk, 0.724; for AHA risk, 0.664; P<0.0001).

CONCLUSIONS

Risk stratification as proposed in the 2007 AHA guideline is simple, accessible to patients and providers, and identifies cardiovascular risk with accuracy similar to that of the current Framingham algorithm. Clinical Trial Registration- clinicaltrials.gov. Identifier: NCT00000611.

Potential health-modulating effects of isoflavones and metabolites via activation of PPAR and AhR

Isoflavones have multiple actions on cell functions. The most prominent one is the activation of estrogen receptors. Other functions are often overlooked, but are equally important and explain the beneficial health effects of isoflavones. Isoflavones are potent dual PPARα/γ agonists and exert anti-inflammatory activity, which may contribute to the prevention of metabolic syndrome, atherosclerosis and various other inflammatory diseases. Some isoflavones are potent aryl hydrocarbon receptor (AhR) agonists and induce cell cycle arrest, chemoprevention and modulate xenobiotic metabolism. This review discusses effects mediated by the activation of AhR and PPARs and casts a light on the concerted action of isoflavones.

Changes in cardiovascular hospitalization and comorbidity of heart failure in the United States: findings from the National Hospital Discharge Surveys 1980-2006

OBJECTIVE

This study aimed to update the long-term trend of coronary heart disease (CHD), cerebrovascular disease (CBVD), and heart failure (HF) hospitalization rates and HF comorbidity among adults aged 65 and older in the United States.

METHODS

Data from the National Hospital Discharge Surveys between 1980 and 2006 were used. CHD, CBVD, and HF were defined using the principal (first-listed) diagnosis of disease at hospital discharge according to the ICD-9-CM code. Census estimated population data (2000) were used to estimate age and gender-specific hospitalization rates.

RESULTS

Age-adjusted CHD and CBVD hospitalization rates have significantly decreased between 1980 and 2006, with an estimated annual decrease rate of 2.24% for CHD and 1.55% for CBVD in men, and 2.36% for CHD and 1.34% for CBVD in women. However, the absolute numbers of CHD and CBVD hospitalization continued to increase partly because of the aging population. Furthermore, HF hospitalization rates have significantly increased with an estimated annual rate increase of 1.20% in men and 1.55% in women between 1980 and 2006. Of six selected co-morbidities, about 50% in men and 40% in women with HF had a coexisting disease of CHD, followed by chronic obstructive pulmonary disease, diabetes mellitus, renal failure, and pneumonia.

CONCLUSIONS

While the burden of CHD and CBVD remains the major public health problem, HF has emerged as a new challenge in cardiovascular disease control, characterized by increased trends of HF hospitalization and increased comorbidities from major diseases.

Cardiometabolic risk among African American women: a pilot study

OBJECTIVE

This study aimed to determine the associations of the Homeostatic Model of Assessment-insulin resistance (HOMA-ir), acanthosis nigricans, high-sensitivity C-reactive protein (hs-CRP), and plasminogen activator inhibitor-1 (PAI-1) with 2 of the commonly used definitions of metabolic syndrome (Adult Treatment Panel III [ATP III] and International Diabetes Federation [IDF]) among reproductive-age, healthy, free-living African American women.

METHODS

A pilot study with a cross-sectional design examined 33 African American women aged 20 to 46 years (mean [SD], 31.24 [7.25] years) for the presence of metabolic syndrome determined by ATP III and IDF criteria, insulin resistance (HOMA-ir and/or acanthosis nigricans), degree of inflammation (hs-CRP), and presence of dysfibrinolysis (PAI-1).

RESULTS

HOMA-ir identified insulin resistance in 27 (81.8%) women, whereas the presence of acanthosis nigricans indicated that 16 (48%) of these women manifested insulin resistance. Metabolic syndrome was found in 7 women (21.2%) by ATP III or in 9 (27.3%) women by IDF criteria. Bivariate correlations showed associations between HOMA-ir and waist circumference, body mass index (BMI), acanthosis nigricans, and the ATP III and IDF definitions for metabolic syndrome. Plasminogen activator inhibitor-1 was significantly correlated with waist circumference, BMI, fasting glucose, HOMA-ir, and ATP III. Both HOMA-ir and PAI-1 were significantly and negatively correlated with high-density lipoprotein cholesterol. High-sensitivity CRP was significantly correlated with BMI and 2-hour postglucose.

CONCLUSION

Both dysfibrinolysis (PAI-1 levels) and insulin resistance (HOMA-ir), when individually regressed on the ATP III definition of metabolic syndrome, explained 32% and 29% of the respective variance. The addition of HOMA-ir measurement may significantly improve early recognition of cardiometabolic risk among reproductive-age African American women who have not yet met the criteria for the ATP III or IDF definitions of metabolic syndrome. Likewise, acanthosis nigricans is potentially a clinically significant screening tool when used to determine early recognition of insulin resistance and/or cardiometabolic risk among this population. African American women's risk for cardiovascular disease is likely underestimated based on the sole use of ATP III criteria for diagnosis of metabolic syndrome. Clinicians should consider a broader definition of risk than that contained within ATP III. Inclusion of biomarkers of inflammation and dysfibrinolysis, along with measures of insulin resistance, may add to early detection of cardiometabolic risk and ultimate reduction in cardiovascular health disparities among African American women.

Longitudinal impact of physical activity on lipid profiles in middle-aged adults: the Atherosclerosis Risk in Communities Study

Evidence exists that increased levels of physical activity decrease the population burden of cardiovascular disease (CVD). Although risk factors for CVD, including plasma lipids and lipoproteins, have been associated with physical activity, studies including a sizeable number of minority participants are lacking. Our purpose was to interrogate the longitudinal effect of physical activity on plasma lipids and lipoproteins in the African American and white participants of the Atherosclerosis Risk in Communities (ARIC) Study. Nine years of follow-up data on 8,764 individuals aged 45-64 years at baseline were used in linear mixed-effects models to estimate the association between increases in baseline physical activity on mean change in HDL, LDL, total cholesterol, and triglyceride levels. Increases in the level of activity were associated with increases in HDL in all strata and decreases in triglycerides among white participants. Physical activity was associated with LDL in all women, while the association with total cholesterol was limited to African American women. This study is one of the few to investigate the effect of physical activity on lipids and lipoproteins in a race- and sex-specific manner. Overall our results highlight the importance of physical activity on plasma lipid profiles and provide evidence for novel differential associations.

Obesity reduction black intervention trial (ORBIT): six-month results

The Obesity Reduction Black Intervention Trial (ORBIT) is a randomized controlled trial designed to assess the efficacy of a culturally proficient 6-month weight loss intervention followed by a 1-year maintenance intervention. This article describes the results of the 6-month weight loss intervention. Two hundred thirteen obese black women aged 30-65 years were randomized to the intervention group or a general health control group. The intervention consisted of a 6-month culturally adapted weight loss program that targeted changes in diet and physical activity patterns. Weight, dietary intake, and physical activity were measured at baseline and 6 months. A total of 198 women (93%) completed both the baseline and postintervention assessments. Women in the intervention group lost significantly more weight than women in the control group (P < 0.001). However, weight change was variable within the intervention group, with a maximum weight loss of 19.4% of initial body weight and a maximum weight gain of 6.4% of initial body weight. Women in the intervention group also showed significant improvements in fruit intake (P < 0.01), Healthy Eating Index score (P < 0.001), and moderate (P = 0.05), and vigorous (P < 0.001) physical activity compared to women in the control group. This study demonstrates that a culturally adapted program can successfully promote weight loss in obese black women. However, average weight loss was relatively modest, and weight change varied widely within the intervention group. Further research is needed in order to develop programs that will allow more black women to achieve their weight loss goals..

Independent role of blood pressure on cardiovascular risk factors in nondiabetic, obese African-American women with family history of type 2 diabetes: Implications for metabolic syndrome components

African-American women (AAW) suffer disproportionately from hypertension and its consequences. We investigated the significance of systolic and diastolic blood pressure (SBP/DBP) as components of metabolic syndrome (MetS) in nondiabetic, overweight/obese AAW. We studied 258 AAW (mean age, 42.4 +/- 8.4 years and body mass index (BMI), 33.4 +/- 8.0 kg/m(2)) in a cross-sectional manner. We estimated the prevalence of MetS and its components using Adult Treatment Panel (ATP III) criteria, insulin sensitivity (Si), insulin resistance (HOMA-IR), and cardiovascular disease risk factors according to the tertiles of blood pressure (BP). Mean age and BMI did not differ with increases in BP tertiles. At screening, 35.7% of our subjects were hypertensive. MetS was found in 32.2% of our AAW. Prevalence of MetS increased as the tertiles of BP increased (SBP = first [10.5%], second [15.1%], third [58.1%], and DBP = first [9.3%], second [23.3%], third [54.7%]). We found that the components of Adult Treatment Panel (ATP) did not track with the corresponding BP tertiles. However, the prevalence of individuals meeting ATP III criteria for BP was highest in the third tertile of both SBP and DBP. Consequently, the prevalence of MetS was highest in the third vs. first and second tertiles. Using linear regression analysis, SBP and DBP did not correlate with the conventional cardiovascular risk factors, HOMA-IR, or Si. In overweight/obese AAW, we found the components of MetS do not track with BP. In the absence of elevated BP, the prevalence of MetS appears to be very low in overweight and obese AAW. Conversely, elevated BP or hypertension was associated with remarkably higher rates of MetS in our AAW. Therefore BP criteria constitute an important and independent determinant of ATP III definition of MetS in AAW.

Metabolic syndrome components in african-americans and European-american patients and its relation to coronary artery disease

A number of factors used to define the metabolic syndrome (MS) differ between African-American and European-American patients, which raises the question whether the individual constellation of MS components would impact cardiovascular risk. Our objectives were to assess the association between the MS and coronary artery disease (CAD) across ethnicities and to explore whether the constellation used to define the syndrome would impact any such association. We studied the distribution of the MS and its relation to CAD in 304 European-American subjects and 224 African-American subjects undergoing diagnostic coronary angiography. The overall prevalence of the MS in European-American and African-American subjects were 65.5% and 49.1%, respectively. Compared with European-American subjects, the lipid components of the syndrome were less frequent among African-American subjects (44% vs 64% [p <0.001] for high-density lipoprotein [HDL] cholesterol and 21% vs 51% [p <0.001] for triglyceride, respectively). The prevalence of CAD was significantly higher in subjects with MS across ethnicity (71.1% of European-American subjects and 56.6% of African-American subjects, p = 0.017 and p = 0.046, respectively). Multiple regression analyses demonstrated an association of blood pressure and HDL cholesterol with CAD among European-American subjects, which remained significant taking other risk factors into account (r(2) = 0.542, p <0.001). In conclusion, presence of CAD was more common among subjects with MS independently of ethnicity. Of the MS components, blood pressure was associated with CAD among European-American subjects. Although our findings may not be directly extrapolated to the population at large, they illustrate the importance of a high-risk metabolic environment as a cardiovascular risk factor.

The evolving definitions and increasing prevalence of the metabolic syndrome

The metabolic syndrome (MetS) represents a cluster of metabolic abnormalities that predisposes an individual to a greater risk of developing coronary heart disease and type 2 diabetes. The condition is widespread among adults from developed nations, and progresses in frequency with age. In recent years, several organizations have proposed diagnostic criteria that could be used by clinical practitioners or for research purposes. While the core components of the MetS have generally been sustained among the various proposed definitions, the number of features required for the MetS to be diagnosed and the cut-off points indicating metabolic perturbations have differed quite significantly between organizations. This has led to considerable confusion among clinicians and health professionals. The present review aims to discuss the different definitions of the MetS, focusing on their application in clinical or research settings. A brief overview of the increasing prevalence of the MetS will also be presented.

The epidemiology of obesity

In the United States, obesity among adults and overweight among children and adolescents have increased markedly since 1980. Among adults, obesity is defined as a body mass index of 30 or greater. Among children and adolescents, overweight is defined as a body mass index for age at or above the 95th percentile of a specified reference population. In 2003-2004, 32.9% of adults 20-74 years old were obese and more than 17% of teenagers (age, 12-19 y) were overweight. Obesity varies by age and sex, and by race-ethnic group among adult women. A higher body weight is associated with an increased incidence of a number of conditions, including diabetes mellitus, cardiovascular disease, and nonalcoholic fatty liver disease, and with an increased risk of disability. Obesity is associated with a modestly increased risk of all-cause mortality. However, the net effect of overweight and obesity on morbidity and mortality is difficult to quantify. It is likely that a gene-environment interaction, in which genetically susceptible individuals respond to an environment with increased availability of palatable energy-dense foods and reduced opportunities for energy expenditure, contributes to the current high prevalence of obesity. Evidence suggests that even without reaching an ideal weight, a moderate amount of weight loss can be beneficial in terms of reducing levels of some risk factors, such as blood pressure. Many studies of dietary and behavioral treatments, however, have shown that maintenance of weight loss is difficult. The social and economic costs of obesity and of attempts to prevent or to treat obesity are high.

Interrelationship Between Insulin Resistance and Menopause on the Metabolic Syndrome and Its Individual Component Among Nondiabetic Women in the Kinmen Study

BACKGROUND

The literature to date is not clear as to whether any interactive effect exists between insulin resistance and menopause on the metabolic syndrome and its individual components. We explored this issue in 4107 homogeneous, nondiabetic Chinese women in the Kinmen Study.

METHODS

Overnight fasting blood samples were drawn for glucose, insulin, lipid, and other biochemical measurements. Demographic and clinical variables including body mass index, waist circumference, and blood pressure were measured and documented during face-to-face interviews with structured questionnaires. Menstrual history was used to define menopause as the absence of menses for 12 consecutive months.

RESULTS

Approximately 16% of premenopausal women (390/2423) were insulin-resistant. After adjustment for age, body mass index, lifestyle, and diet, both menopause and insulin resistance were independently and significantly correlated with metabolic syndrome. For each component of the metabolic syndrome, besides the main effect, the interaction (insulin resistance x menopause) had significant correlation with systolic blood pressure, diastolic blood pressure, and waist circumference.

CONCLUSIONS

Both insulin resistance and menopause have significant effects on metabolic syndrome independent of age and obesity. In premenopausal and nondiabetic women, various degrees of insulin resistance exist. The synergistic contribution of insulin resistance and menopause to components of the metabolic syndrome were observed with systolic blood pressure, diastolic blood pressure, and waist circumference. This requires further study.

Development of age-specific adolescent metabolic syndrome criteria that are linked to the Adult Treatment Panel III and International Diabetes Federation criteria

OBJECTIVES

The study objectives were to develop age-specific adolescent metabolic syndrome (MetS) criteria that were linked to the health-based Adult Treatment Panel III (ATP) and International Diabetes Federation (IDF) adult criteria.

BACKGROUND

There has been no consistency in the criteria used to diagnose the MetS in adolescents. Studies have either applied adult criteria or arbitrarily chosen adolescent high-risk cut-points.

METHODS

The adolescent (12 to 19 years old) MetS criteria developed in this study were linked to the ATP and IDF adult criteria with LMS growth curve modeling for each MetS component (waist circumference, systolic and diastolic blood pressure, high-density lipoprotein cholesterol, triglycerides, and glucose). Nationally representative data from the National Health and Nutrition Examination Surveys were used to develop the growth curves.

RESULTS

The growth curves for each MetS component passed through the ATP and IDF cut-points at 20 years of age such that adolescent cut-points were linked to the adult values. Age- and gender-specific cut-points for each MetS component were developed that can be used to define high-risk values in 12- to 19-year-olds. The prevalence of MetS in adolescents nearly doubled over the last decade and was 7.6% on the basis of the newly developed ATP adolescent criteria and 9.6% on the basis of the newly developed IDF adolescent criteria.

CONCLUSIONS

These new criteria should provide improved and age-appropriate approaches for diagnosing MetS among adolescents.

Effects of PPAR gamma agonists on cardiovascular function in obese, non-diabetic patients

Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors, and when activated by their ligands, they induce perixosome proliferation. Three receptors have been identified: PPAR gamma, PPAR delta, and PPAR alpha, all with different tissue expression. PPAR gamma is predominantly expressed in adipose tissue and regulates the formation of fat cells and their function. The effect of PPAR gamma activation is to enhance the action of insulin in insulin-sensitive tissue by increasing peripheral glucose disposal and decreasing hepatic glucose production. The thiazolidinediones (TZDs) are a class of medications used for treatment and possibly the prevention of type 2 diabetes, which are potent agonists for the PPAR gamma receptor. Because the thiazolidinediones target insulin resistance, these agents may improve many of the risk factors associated with obesity and insulin resistance including dyslipidemia, hypertension, impaired fibrinolysis, and atherosclerosis. The impact of the thiazolidinediones on cardiovascular mortality is currently unclear but it appears that the thiazolidinediones exert numerous non-glycemic effects that may improve cardiovascular outcomes. Several non-TZD PPAR gamma agonists and combined PPAR gamma/alpha effect on cardiovascular disease are also being evaluated. These drugs have anti-inflammatory and vascular properties and are currently the subject of numerous studies targeting the primary and secondary prevention of macrovascular disease in patients with diabetes and insulin resistance and might be developed as anti-atherogenic agents on the basis of their actions.

Severity of cardiovascular disease in women: relation with exposure to endogenous estrogen

OBJECTIVES

Coronary artery disease (CAD) is more common in men than in women. Endogenous sex steroids may be the main factor responsible, as long-term estrogen action appears to be protective. The aim of the study was to investigate the predisposing factors responsible for the severity of CAD in women.

METHODS

One hundred and eight women (100 menopausal) undergoing coronary angiography were studied. Reproductive function was recorded. The severity of CAD was assessed by the number of arteries with severe stenosis, the presence of angina and myocardial infarctions (MI).

RESULTS

The time since menopause (TSM) was significantly longer in women with angina and with MIs compared to those without (20.3+/-8.7 years versus 15.8+/-8.7 years and 22.6+/-8.6 years versus 18.1+/-8.9 years, p<0.05), independently of chronological age. The age at menopause was significantly younger in women who had 2 MIs compared to those with 1 or 0 MI (41.5+/-3.5, 47.5+/-5.3 and 48.4+/-5.4 years, respectively; p=0.04); the total duration of menstrual cyclicity was inversely related to the number of MIs (35.6+/-5.8, 34.2+/-5.3 and 28.3+/-3.3 years, 0, 1 and 2 MIs, respectively; p=0.03).

CONCLUSIONS

The severity of CAD in women referred for coronary angiography is correlated with measures of exposure to endogenous estrogen. Both the TSM and the age at menopause are aggravating factors for MI, independently of age. There is an independent protective effect of the duration of estrogen exposure on the number of MIs; this has not been reported before and supports the protective role of the length of exposure to endogenous estrogen, especially for the occurrence of MI in this selected group of women.

Obesity, Insulin Resistance, and the Metabolic Syndrome

Background— Insulin resistance is strongly associated with obesity and other components of the metabolic syndrome (MS). The relative importance of these components in the determination of endothelial function is unknown. Furthermore, there is conflicting evidence about whether ethnic differences exist in the relative importance of these components in regard to other cardiovascular outcomes. We evaluated the contributions of insulin resistance, obesity, and the other components of the MS to impaired endothelial function.

Methods and Results— The relationships of the MS components (as defined according the National Cholesterol Education Program) and insulin resistance (estimated using the homeostasis model) with endothelium-dependent vasodilation were examined in 42 white and 55 black subjects. Endothelium-dependent vasodilation was assessed as the increment in leg blood flow (measured by thermodilution) after exposure to methacholine chloride. Waist circumference, glucose, blood pressure, and insulin resistance distributions did not differ between ethnic groups; blacks in our sample had higher HDL cholesterol (1.31 versus 1.09 mmol/L; P <0.001) and lower triglyceride levels (1.01 versus 1.37 mmol/L; P =0.005) than white subjects. In the absence of the MS, black subjects exhibited reduced endothelium-dependent vasodilation compared with white subjects ( P =0.005), and both groups demonstrated significantly worse endothelial function when the MS was present (maximal increase in leg blood flow: blacks: 107±9% MS absent, 53±16% MS present; whites: 163±16% MS absent, 54±18% MS absent; P =0.007, MS absent versus present; P =NS for interaction of ethnicity and MS). Multivariable regression analysis examining relationships of endothelial function with the 5 MS components (analyzed as continuous variables) revealed independent relationships only with waist circumference ( P =0.01) and systolic blood pressure ( P =0.02). Waist circumference was no longer independently associated after adding insulin resistance to the modeling ( P =0.02 for log of homeostasis model index of insulin resistance, P =0.02 for systolic blood pressure). Ethnicity still exerted an independent effect on endothelial function after accounting for the above components ( P =0.04 for an additional effect of ethnic status on endothelial function), with an ethnic difference in the effect of insulin resistance on endothelial function ( P =0.046 for interaction of ethnicity and log of homeostasis model index of insulin resistance).

Conclusions— These findings suggest that insulin resistance and systolic blood pressure are the principal determinants of endothelial dysfunction in the MS and that there are ethnic differences in the relative importance of these factors. These differences may imply different benefits from treatments targeting blood pressure or insulin resistance in different ethnic groups.

Enlarged Waist Combined With Elevated Triglycerides Is a Strong Predictor of Accelerated Atherogenesis and Related Cardiovascular Mortality in Postmenopausal Women

BACKGROUND

Upward trends of obesity urge more effective identification of those at cardiovascular risk. A simple dichotomous indicator, enlarged waist (> or =88 cm) combined with elevated triglycerides (> or =1.45 mmol/L) (EWET), was shown to offer advantages in identifying individuals with atherogenic "lipid overaccumulation" compared with other indicators, including the metabolic syndrome defined by the National Cholesterol Education Program (MS-NCEP). Whether EWET offers superior disease and event prediction in postmenopausal women, however, remains unknown.

METHODS AND RESULTS

A community-based sample of 557 women (48 to 76 years of age) were followed up for 8.5+/-0.3 years to assess the utility of EWET and MS-NCEP in estimating the risk of all-cause and cardiovascular mortality and the annual progression rate of aortic calcification. At baseline, 15.8% of women had EWET and 17.6% had MS-NCEP. All-cause mortality and cardiovascular mortality were increased in carriers of the dichotomous indicators (P<0.001). After adjustment for age, smoking, and LDL cholesterol, presence of EWET was associated with a 4.7-fold (95% CI, 2.2 to 9.8; P<0.001) increased risk and presence of MS-NCEP was associated with a 3.2-fold (95% CI, 1.5 to 6.5; P<0.001) increased risk for fatal cardiovascular events. Exclusion of women with prevalent diabetes did not change these trends; respective hazard ratios were 4.2 (95% CI, 1.9 to 9.3; P<0.001) and 2.5 (95% CI, 1.1 to 5.5; P<0.05). Among those who were discordant for EWET and MS-NCEP at baseline, those who had EWET alone (n=21) had a higher annual progression rate of aortic calcification compared with those who had MS-NCEP alone (n=31; P<0.05).

CONCLUSIONS

The combined presence of EWET may be the best indicator of cardiovascular risk in postmenopausal women. Other components of the MS-NCEP add little medical value to screening in general practices.

What is the relationship between exercise and metabolic abnormalities? A review of the metabolic syndrome

Prevention of the metabolic syndrome and treatment of its main characteristics are now considered of utmost importance in order to combat the epidemic of type 2 diabetes mellitus and to reduce the increased risk of cardiovascular disease and all-cause mortality. Insulin resistance/hyperinsulinaemia are consistently linked with a clustering of multiple clinical and subclinical metabolic risk factors. It is now widely recognised that obesity (especially abdominal fat accumulation), hyperglycaemia, dyslipidaemia and hypertension are common metabolic traits that, concurrently, constitute the distinctive insulin resistance or metabolic syndrome. Cross-sectional and prospective data provide an emerging picture of associations of both physical activity habits and cardiorespiratory fitness with the metabolic syndrome. The metabolic syndrome, is a disorder that requires aggressive multi-factorial intervention. Recent treatment guidelines have emphasised the clinical utility of diagnosis and an important treatment role for 'therapeutic lifestyle change', incorporating moderate physical activity. Several previous narrative reviews have considered exercise training as an effective treatment for insulin resistance and other components of the syndrome. However, the evidence cited has been less consistent for exercise training effects on several metabolic syndrome variables, unless combined with appropriate dietary modifications to achieve weight loss. Recently published randomised controlled trial data concerning the effects of exercise training on separate metabolic syndrome traits are evaluated within this review. Novel systematic review and meta-analysis evidence is presented indicating that supervised, long-term, moderate to moderately vigorous intensity exercise training, in the absence of therapeutic weight loss, improves the dyslipidaemic profile by raising high density lipoprotein-cholesterol and lowering triglycerides in overweight and obese adults with characteristics of the metabolic syndrome. Lifestyle interventions, including exercise and dietary-induced weight loss may improve insulin resistance and glucose tolerance in obesity states and are highly effective in preventing or delaying the onset of type 2 diabetes in individuals with impaired glucose regulation. Randomised controlled trial evidence also indicates that exercise training decreases blood pressure in overweight/obese individuals with high normal blood pressure and hypertension. These evidence-based findings continue to support recommendations that supervised or partially supervised exercise training is an important initial adjunctive step in the treatment of individuals with the metabolic syndrome. Exercise training should be considered an essential part of 'therapeutic lifestyle change' and may concurrently improve insulin resistance and the entire cluster of metabolic risk factors.

Comparison of dietary intakes associated with metabolic syndrome risk factors in young adults: the Bogalusa Heart Study

BACKGROUND

Previous studies suggested that dietary intakes affect individual risk factors associated with metabolic syndrome.

OBJECTIVE

The objective of this study was to examine dietary intakes in 1181 young adults aged 19-38 y (38.1% men; 25% African Americans and 75% whites) in relation to metabolic syndrome risk factors in the Bogalusa Heart Study.

DESIGN

Participants were stratified into 3 groups according to the number of risk factors (0, 1-2, >/=3) associated with the metabolic syndrome according to the diagnostic criteria of the National Cholesterol Education Program, and dietary intakes were compared between the groups with a cross-sectional analysis.

RESULTS

After adjustment for age, total energy intake, body mass index, and physical activity, mean (+/-SE) intakes of fruit, fruit juice, and vegetables were significantly higher in subjects who had no risk factors than in subjects who had 1-2 risk factors (3.30 +/- 0.09 compared with 2.99 +/- 0.07 servings/d; P < 0.05). The mean intake of sweetened beverages was lower in subjects who had no risk factors than in subjects who had 1-2 risk factors or >/=3 risk factors among whites (1.45 +/- 0.08 compared with 1.77 +/- 0.07 and 2.22 +/- 0.15 serving/d, respectively, in men; 1.26 +/- 0.06 compared with 1.62 +/- 0.05 and 1.78 +/- 0.13 servings/d, respectively, in women; P < 0.001) but not among African Americans.

CONCLUSION

Our results suggest that low fruit and vegetable consumption and high sweetened beverage consumption are independently associated with the prevalence of metabolic syndrome in specific sex-ethnicity populations.

A quantitative trait locus influences coordinated variation in measures of ApoB-containing lipoproteins

Lipoprotein phenotypes are known to be strongly intercorrelated. These intercorrelations are due to genetic and environmental effects on common metabolic pathways. The purpose of this study was to determine if we could localize genes that exert pleiotropic effects on multiple related lipoprotein traits in humans. Using data from the San Antonio Family Heart Study, we extracted principal components from a set of 12 intercorrelated lipoprotein traits that included phenotypes reflecting lipid and protein concentrations and size distributions for LDLs and HDLs. Five principal components were extracted from the data and all were significantly heritable (h(2) = 0.41-0.57). When subjected to linkage analyses, only one, Component 5, returned a LOD score > or = 3 (LOD score was 3.0 at 38cM on chromosome 15; genome-wide P-value = 0.039). LDL median diameter (-0.529), non-HDLC (-0.422), and ApoB (-0.403) concentrations were the only traits with loadings (absolute value) >0.4, suggesting Component 5 is related to LDL size or perhaps more generally to beta-lipoprotein metabolism. Surprisingly, none of the 12 original lipoprotein traits had a LOD >1 in this region of chromosome 15. These data provide evidence for a novel gene, influencing beta-lipoprotein phenotypes, whose effect(s) is detected only when several lipoprotein traits are considered together.

Metabolic syndrome and effects of conjugated linoleic acid in obesity and lipoprotein disorders: the Québec experience

The health hazards of obesity are well established. However, the fact that all obese individuals are not at equal risk of developing a disease is being increasingly recognized. The regional distribution of body fat has been identified as an important component of the obesity-related health hazards. Among obese individuals, those who accumulate fat predominantly in the abdominal area are more likely to present several metabolic perturbations of the metabolic syndrome, such as increased plasma triacylglycerol and apolipoprotein B concentrations, an elevated ratio of total cholesterol to HDL cholesterol, reduced plasma HDL-cholesterol concentrations, and small, dense LDL particles. This short review focuses on the risk associated with specific features of metabolic syndrome with use of data from the Québec Cardiovascular Study, an ongoing prospective study of traditional and nontraditional risk factors for ischemic heart disease in men. Recent data on the effect of conjugated linoleic acid on risk factors associated with metabolic syndrome are briefly reviewed. Data available to date suggest that conjugated linoleic acid might not be an appropriate dietary alternative for the treatment of metabolic syndrome and its complications.

Ethnic differences in atherosclerosis, cardiovascular disease and lipid metabolism

PURPOSE OF REVIEW

Comparison of risk factors and cardiovascular disease among racial and ethnic groups is a powerful approach to study genetics and lifestyle, or environmental interactions.

RECENT FINDINGS

Most, mean or median, cardiovascular risk factor levels are similar among black and white people. There are much greater differences in the distribution of risk factor level within a specific race and ethnic group than between US populations. There are also very large differences in levels of risk factors for coronary heart disease between specific ethnic migrant populations such as comparing black people in Africa with those in the US, or Japanese people in Japan with those in Hawaii and California. Differences in distribution of risk factors and disease between race and ethnic group are a function of the frequency of specific genotypes and interaction with environmental factors. Several of the most important differences between racial groups are higher blood pressure, lower triglycerides and higher HDL cholesterol among blacks, higher prevalence of diabetes and insulin resistance among Mexican Americans and American Indians, and higher triglyceride levels among the Japanese.

SUMMARY

Further studies of racial and ethnic differences should focus on unique phenotypes and genotypic differences, international and migrant studies and large enough sample sizes to provide robust results. The sprinkling of a percentage of minority participants in each study is worthless. The study of racial and ethnic differences in disease and detection of risk factor levels must be based on solid hypotheses that can evaluate the interaction of lifestyle and possible genetic attributes. Many of the reported ethnic differences in risk factors and disease in US populations are primarily a function of differences in education, socioeconomic variations, and utilization of preventive and clinical treatments.

Ethnic differences in hepatic lipase and HDL in Japanese, black, and white Americans: role of central obesity and LIPC polymorphisms

Hepatic lipase activity (HLA) is a determinant of HDL levels, and a polymorphism in the hepatic lipase gene (LIPC) promoter (C-514T) has been hypothesized to account for higher HDL in blacks and Japanese compared with whites. To determine whether the polymorphism contributes to ethnic differences in HDL, we compared LIPC allele frequencies and HLA in Japanese American (JA; n = 84), black American (BA; n = 94), and white American (WA; n = 110) men and women. The LIPC polymorphism was associated with HLA in all cohorts (BA, P = 0.012; JA, P = 0.008; WA, P = 0.009). WA men had 49% and 58% higher HLA than BA and JA men, respectively (both P < 0.05), yet no differences in HLA were found between the women. The higher HLA in the WA men remained after adjustment for the LIPC polymorphism's effect on HLA (P = 0.037) but was erased after adjustment for waist-to-hip-ratio (P = 0.46). Although the WA men had lower HDL and HDL(3) than the JA and BA men (all P < 0.05), there were no differences in HDL(2), implying that variance in HLA may not underlie the ethnic differences in HDL levels. These results suggest that 1) the LIPC promoter polymorphism contributes to variation in HLA and HDL(2) in the three ethnic groups; 2) WA men had higher HLA than BA and JA men, related to ethnic differences in central adiposity but not LIPC allele frequency; and 3) the higher HLA in WA men did not contribute to the ethnic differences in HDL, as the differences in HDL were made up entirely of differences in HDL(3) and not HDL(2).

Genes, diet and serum lipid concentrations: lessons from ethnically diverse populations and their relevance to coronary heart disease in Asia

PURPOSE OF REVIEW

The burden of coronary heart disease (CHD) in Asia has risen in tandem with socio-economic development and urbanization. Although all ethnic groups have been affected, some appear to be at particularly high risk. The basis of these ethnic differences remains poorly understood.

RECENT FINDINGS

Differing levels of risk factors for CHD have been observed between ethnic groups. Previous studies, however, may be confounded by a large ethnic variation in socio-economic status and place of residence. Few studies have taken dietary factors into account. Recent studies involving Chinese, Malays and Asian Indians living in Singapore suggest that neither dietary nor genetic factors, taken in isolation, sufficiently explain ethnic differences in serum lipid profiles. Several genetic variants in key candidate genes (apolipoprotein E, APOE, cholesteryl ester transfer protein, CETP and hepatic lipase, LIPC) have recently been found to modulate the association between dietary factors and serum lipid concentrations in these ethnic groups and in other populations.

SUMMARY

To fully evaluate the differences in CHD risk between ethnic groups, environmental exposures, including dietary factors need to be carefully evaluated, and gene-environment interactions that may give rise to these differences need to be taken into account. These are critical steps in the development of targeted strategies to contain the epidemic of coronary heart disease in Asia. An understanding of the basis of these differences may also provide insights into the pathogenesis of disease that one cannot get through the examination of more homogenous populations.