Coronary Artery Disease Risk Predicted by Insulin Resistance, Plasma Lipids, and Hypertension In People without Diabetes

The risk of carotid plaque instability in patients with metabolic syndrome is higher in women with hypertriglyceridemia

Background

Metabolic syndrome certainly favors growth of carotid plaque; however, it is uncertain if it determines plaque destabilization. Furthermore, it is likely that only some components of metabolic syndrome are associated with increased risk of plaque destabilization. Therefore, we evaluated the effect of different elements of metabolic syndrome, individually and in association, on carotid plaques destabilization.

Methods

A total of 186 carotid endarterectomies from symptomatic and asymptomatic patients were histologically analysed and correlated with major cardiovascular risk factors.

Results

Metabolic syndrome, regardless of the cluster of its components, is not associated with a significant increase in risk of plaque destabilization, rather with the presence of stable plaques. The incidence of unstable plaques in patients with metabolic syndrome is quite low (43.9 %), when compared with that seen in the presence of some risk factors, but significantly increases in the subgroup of female patients with hypertriglyceridemia, showing an odds ratio of 3.01 (95% CI, 0.25–36.30).

Conclusions

Our data may help to identify patients with real increased risk of acute cerebrovascular diseases thus supporting the hypothesis that the control of hypertriglyceridemia should be a key point on prevention of carotid atherosclerotic plaque destabilization, especially in post-menopausal female patients.

Coronary artery calcification in obese youth: what are the phenotypic and metabolic determinants?

OBJECTIVE

Obesity in adolescence has been associated with increased risk for coronary heart disease in adulthood. This study evaluated subclinical atherosclerosis in obese youth and the underlying risk factors.

RESEARCH DESIGN AND METHODS

Ninety obese adolescents (37 normal glucose tolerant, 27 prediabetes, and 26 type 2 diabetes) underwent evaluation of coronary artery calcifications (CACs) by electron beam computed tomography, aortic pulse wave velocity (PWV), carotid intima-media thickness (IMT), lipids, leptin, inflammatory markers, and body composition (DEXA). A total of 68 underwent evaluation of insulin sensitivity (IS) (hyperinsulinemic-euglycemic clamp) and abdominal adiposity (computed tomography).

RESULTS

A total of 50% had CACs (CAC+: Agatston CAC score ≥1). CAC+ youth had higher BMI, fat mass, and abdominal fat, with no difference in sex, race, IS per fat-free mass (ISFFM), glucose tolerance, PWV, or IMT compared with the CAC- group. PWV was inversely related to IS. In multiple regression analyses with age, race, sex, HbA1c, BMI (or waist circumference), ISFFM, diastolic blood pressure, non-HDL cholesterol, and leptin as independent variables, BMI (or waist) (R(2) = 0.41; P = 0.001) was the significant determinant of CAC; leptin (R(2) = 0.37; P = 0.034) for PWV; and HbA1c, race, and age (R(2) = 0.34; P = 0.02) for IMT.

CONCLUSIONS

Early in the course of obesity, there is evidence of CAC independent of glycemia. The different biomarkers of subclinical atherosclerosis appear to be differentially modulated, adiposity being the major determinant of CAC, hyperglycemia, age, and race for IMT, and leptin and IS for arterial stiffness. These findings highlight the increased cardiovascular disease risk in obese youth and the need for early interventions to reverse obesity and atherosclerosis.

Vinegar-processed ginseng radix improves metabolic syndrome induced by a high fat diet in ICR mice

Ginseng has made a successful transition from the world of traditional tonic remedies to conventional medicine, and since the 1920s ginseng root has been documented to be effective in diabetes, hypertension, dyslipidemia and obesity. Based on this wide spectrum of activity we wondered whether ginseng root extract might also be effective in metabolic syndrome (MetSyn). In a series of investigations to develop a potential anti-MetSyn agent, we prepared a vinegar-processed form of ginseng radix (ginsam, GS) and compared its anti-MetSyn effects to those of non-processed ginseng radix (GR) in an ICR mouse model of MetSyn induced by a high fat diet. GR- and GS-treated mice (500 mg/kg/day for 8 weeks) had an 81% and 90% decrease in insulin resistance respectively, compared to the high fat diet (HFD) control. White adipocyte size was dramatically reduced by 67% and 80% in GR- ahd GS-treated groups respectively, compared to the HFD fed control. This result was reflected by a marked inhibition of weight gain in GS-treated mice (GR vs. GS, 53% vs. 86%). Analysis of ginsenoside composition indicated that prosapogenin Rg3 might be responsible for the anti-MetSyn activity of GS. In conclusion, Vinegar-processed ginseng radix (GS) was found to have a significantly greater anti-MetSyn effect than ginseng radix, and we suggest that ginsam should be subjected to clinical trials in the future, and that the role of prosapogenin Rg3 in the anti-MetSyn effect of ginsam should be confirmed.

Metabolic syndrome is associated with severe coronary artery disease and poor cardiac outcome in end-stage renal disease patients with acute coronary syndrome

OBJECTIVE

People with either end-stage renal disease or metabolic syndrome (MS) are at increased risk for developing coronary artery disease. The impact of MS on coronary artery disease in end-stage renal disease patients, however, remained unclear. We therefore evaluated whether the presence of MS is associated with more coronary lesions and a worse cardiac outcome in end-stage renal disease patients with acute coronary syndrome.

METHODS

We retrospectively examined 76 consecutive end-stage renal disease patients who experienced acute coronary syndrome and underwent cardiac catheterization. Cardiovascular events were compared between the MS and non-MS group.

RESULTS

MS was found in 58 patients and coronary artery disease was found in 63 patients [52 with MS (accounting for 90% of the MS group); 11 without MS (61% of the non-MS); MS vs. non-MS, P=0.01]. Patients with MS had more multi-vessel coronary artery disease (P<0.001) than those without MS. Sixty-nine (MS, 51; non-MS, 18) patients survived the acute coronary syndrome. During the follow-up period (MS, 17.6+/-13.8; non-MS, 19.9+/-11.7 months), 12 patients with MS (24%) and none without MS died owing to cardiovascular events (MS vs. non-MS, P=0.028). Regarding major cardiac events, including cardiac death, repeat non-fatal myocardial infarction, and repeat revascularization, the non-MS group had a higher probability of event-free survival (P<0.0001).

CONCLUSIONS

In patients with end-stage renal disease complicated by acute coronary syndrome, MS is frequently seen and associated with a higher probability of coronary artery disease involving multiple coronary branches and a higher probability of cardiac death and major cardiac events. Therefore, detection of MS in such patients is useful for risk stratification.

Altered calcium homeostasis is correlated with abnormalities of fasting serum glucose, insulin resistance, and beta-cell function in the Newfoundland population

Alteration of extracellular calcium concentration may be involved in glucose metabolism in a number of pathways. The present study was designed to investigate the relationship between total serum calcium and 1) fasting serum glucose, 2) insulin, 3) insulin resistance, and 4) beta-cell function in 1,182 healthy subjects from the province of Newfoundland and Labrador, Canada. All variables were log10 transformed, and confounding factors including age, trunk fat percentage, serum phosphorus, magnesium, 25-OH vitamin D, and parathyroid hormone were adjusted before analyses. Significant positive correlations between glucose and insulin resistance with calcium were found in both sexes, whereas an inverse correlation between beta-cell function and calcium was found only in women. Similar results were found in medication-free women and men, as well as in pre- and postmenopausal women. Subjects with low calcium levels had the lowest concentration of glucose and the least insulin resistance, whereas subjects with high calcium levels had the highest concentration of glucose and insulin resistance in women but not in men. This relationship remained after calcium was adjusted for 25-OH vitamin D and parathyroid hormone. Our results suggest that alteration of serum calcium homeostasis is significantly correlated with the abnormality of glucose level, insulin resistance, and beta-cell function.

Hyperhomocysteinemia as a component of syndrome X

Syndrome X, a cluster of several metabolic disorders that includes hyperinsulinemia, hypertriglyceridemia, and hypertension, is associated with severe vascular morbidity. Hyperhomocysteinemia is another risk factor for cardiovascular and cerebrovascular diseases, often exhibited by insulin-resistant patients. In the current study, we investigated the relationship between syndrome X and hyperhomocysteinemia in a rat model. Two groups of rats were fed either fructose-enriched diet or standard rat chow for 5 weeks. Systolic blood pressure (SBP), as well as fasting plasma insulin, triglycerides, total cholesterol, and total homocysteine levels, were determined at the beginning and at the end of the study. A complete metabolic syndrome was induced by the fructose-enriched diet, including hyperinsulinemia, hypertriglyceridemia, and hypertension. Homocysteine concentration was 72% higher after 5 weeks on the fructose diet (8.49 +/- 1.6 v 4.92 +/- 0.9 micromol/l, P<.01). Insulin, triglycerides, SBP, and homocysteine levels were insignificantly changed during 5 weeks on standard rat chow. Homocysteine was positively and significantly correlated with any original component of syndrome X (r=0.565, P=.014 with insulin, r=0.662, P=.001 with triglycerides, and r=0.774, P<.001 with SBP). The results of the present study indicate that hyperhomocysteinemia is an integral component of this rat model of syndrome X. It is thus highly likely that hyperhomocysteinemia is an integral component of the human syndrome X as well, and thereby contributes to the overall high vascular risk associated with this condition.

Chitosan decreases total cholesterol in women: a randomized, double-blind, placebo-controlled trial

BACKGROUND

Hypercholesterolemia is an important risk factor for cardiovascular disease. Orally administered chitosan binds lipids in the small intestine and reduces their absorption. Chitosan has been shown to decrease serum cholesterol in animal and human studies. This study investigated the effectiveness of chitosan in reducing serum cholesterol without concomitant diet therapy.

METHODS

Ninety female volunteers (age 34-70 y) with confirmed mild to moderate hypercholesterolemia were enrolled into the study. They were randomly assigned to receive chitosan (1.2 g per day) or placebo in a double-blind manner. Serum lipids, body weight and adverse events were assessed at baseline and after 28 and 56 days of treatment. Subjects maintained their usual diet and documented the type and gross amount of food consumed.

RESULTS

Eighty-four subjects (41 chitosan, 43 placebo) were included in the analysis. Chitosan significantly (F=3.19, P=0.04) reduced total cholesterol compared to placebo. In a subgroup of subjects with over 60 y of age, chitosan group significantly reduced total and LDL cholesterol (F=4.21, P=0.02, and F=3.46, P=0.04, respectively) compared with placebo. Adverse effects were few; no serious events were reported.

CONCLUSION

Our results demonstrate that chitosan is safe and effective for lowering cholesterol. However, the effect of chitosan for decreasing cholesterol is mild.

Risk factor groupings related to insulin resistance and their synergistic effects on subclinical atherosclerosis: the atherosclerosis risk in communities study

The extent to which groupings of insulin resistance-related cardiovascular risk factors synergize to produce atherosclerosis beyond what is expected from their additive effects is uncertain. The objective of this study was to measure interactions among groupings of the features of the insulin resistance syndrome (IRS) on carotid intimal-medial thickness (IMT). This cross-sectional study used baseline data from the Atherosclerosis Risk in Communities Study on 11,790 adults aged 45-64 years without diagnosed diabetes, treated dyslipidemia, or coronary heart disease. The main outcome was carotid IMT, assessed using B-mode ultrasound. The excess carotid IMT attributable to each IRS grouping was determined using multiple linear regression models. There were 57 possible combinations of six IRS components (hypertension, hyperinsulinemia, obesity, hypertriglyceridemia, low HDL cholesterol, and hyperglycemia). In multivariate analysis, 29 of the 57 groupings were associated with excess carotid IMT. Individuals with all six IRS components had the greatest excess IMT compared with those without this grouping (71 micro m; 95% CI 40-102 micro m). The groupings most strongly associated with excess carotid IMT included hypertension and hypertriglyceridemia. Interventions aimed at ameliorating the IRS may produce reductions in atherosclerotic risk beyond that predicted by treatment of individual IRS-related risk factors.

Insulin resistance: cellular and clinical concepts

Insulin resistance is defined as a clinical state in which a normal or elevated insulin level produces an attenuated biologic response. Specifically, the biologic response most studied is insulin-stimulated glucose disposal, yet the precise cellular mechanism responsible is not yet known. However, the presence of insulin resistance is observed many years before the onset of clinical hyperglycemia and the diagnosis of Type 2 diabetes. Insulin resistance at this stage appears to be significantly associated with a clustering of cardiovascular risk factors predisposing the individual to accelerated cardiovascular disease. An overview of insulin resistance and the associated clinical insulin resistant state will be discussed.