Insulin resistance and intima-media thickness in the carotid and femoral arteries of clinically healthy 58-year-old men. The Atherosclerosis and Insulin Resistance Study (AIR)

Metabolic Health and Carotid Intima-Media Thickness: Association of Different Definitions in Women

The concept of metabolic health and the metabolic syndrome is to identify subjects at a higher cardiovascular risk. However, many definitions are currently in use, and it is uncertain which is the best in identifying at-risk subjects. We performed a cross-sectional study whereby women were invited to participate and were assessed for several anthropometric and biochemical parameters. Carotid intima-media thickness (CIMT) was measured in both common carotid arteries in each participant. The study cohort consisted of 203 white premenopausal women with a mean age of 38.3 ± 5.4 years. The prevalence of the metabolically unhealthy varied from 7.3% to 61.6%, according to the definition used. The prevalence of the metabolic syndrome, as defined by the International Diabetes Federation, was 20.7%. Women with a metabolically unhealthy phenotype had a higher referent CIMT for all definitions of metabolic health. Defining metabolically unhealthy phenotype as having <2 abnormalities using the National Cholesterol Education Program Expert Panel on Detection, Evaluation, And Treatment of High Blood Cholesterol In Adults (NCEP-ATPIII) cutoffs had the highest odds ratio for an abnormal CIMT. In conclusion, we found that in a contemporary cohort of middle-aged women, the NCEP-ATPIII definition of the metabolic syndrome was more strongly associated with atherosclerosis as determined by the CIMT than the International Diabetes Federation definition or other definitions of metabolic health; it was also more strongly associated than body mass index or waist circumference. Our results need to be validated by other investigators in other populations.

Statin therapy is not warranted for a person with high LDL-cholesterol on a low-carbohydrate diet

PURPOSE OF REVIEW

Although there is an extensive literature on the efficacy of the low carbohydrate diet (LCD) for weight loss and in the management of type 2 diabetes, concerns have been raised that the LCD may increase cardiovascular disease (CVD) risk by increasing the level of low-density lipoprotein cholesterol (LDL-C). We have assessed the value of LDL-C as a CVD risk factor, as well as effects of the LCD on other CVD risk factors. We have also reviewed findings that provide guidance as to whether statin therapy would be beneficial for individuals with high LDL-C on an LCD.

RECENT FINDINGS

Multiple longitudinal trials have demonstrated the safety and effectiveness of the LCD, while also providing evidence of improvements in the most reliable CVD risk factors. Recent findings have also confirmed how ineffective LDL-C is in predicting CVD risk.

SUMMARY

Extensive research has demonstrated the efficacy of the LCD to improve the most robust CVD risk factors, such as hyperglycemia, hypertension, and atherogenic dyslipidemia. Our review of the literature indicates that statin therapy for both primary and secondary prevention of CVD is not warranted for individuals on an LCD with elevated LDL-C who have achieved a low triglyceride/HDL ratio.

A detailed lipoprotein profile in relation to intima-media thickness and echogenicity of three major arteries

OBJECTIVE

To investigate differences in risk-factor profile, with special emphasis on detailed characterization of the lipoprotein profile, for intima-media thickness (IMT) and echogenicity of the intima-media complex (IM-GSM) in three major arteries: the carotid, femoral and brachial arteries.

METHODS

IMT and IM-GSM were measured by ultrasound in the carotid, femoral and brachial arteries in 778 subjects, all aged 75 years (50% women), in the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study, in which a detailed lipoprotein profile was also determined by nuclear magnetic resonance spectroscopy.

RESULTS

First, IMT was considerably lower, and IM-GSM higher, in the brachial artery compared to the other two arteries. Second, IMT and IM-GSM in the arteries were related to each other. Third, significant different traditional risk-factor profiles were seen for both IMT and IM-GSM, with generally weaker relationships for IMT in the femoral and brachial arteries compared with the carotid artery. Fourth, the strength of associations between an atherogenic lipoprotein profile and IMT in the carotid artery was attenuated in the femoral artery and virtually absent in the brachial artery. Fifth, slightly different lipoprotein profiles were seen for IM-GSM in the three arteries.

CONCLUSION

Differences between the carotid, femoral and brachial artery IMT and IM-GSM were seen regarding the traditional risk factors, as well as the lipoprotein profile.

Association between carotid intima-media thickness and fasting blood glucose level: A population-based cross-sectional study among low-income adults in rural China

Aims/Introduction

Carotid intima‐media thickness (CIMT) is an established predictor of cardiovascular disease and stroke. We aimed to identify the association between CIMT and blood glucose, as well as the risk factors associated with increased CIMT in a low‐income Chinese population.

Materials and Methods

Stroke‐free and cardiovascular disease‐free residents aged ≥45 years were recruited. B‐mode ultrasonography was carried out to measure CIMT.

Results

There were 2,643 participants (71.0%) in the normal group, 549 (14.7%) in the impaired fasting glucose group and 533 (14.3%) in the diabetes mellitus group. The determinants of increased CIMT were older age; male sex; low education; hypertension; smoking; high levels of systolic blood pressure, fasting blood glucose and low‐density lipoprotein cholesterol; and low levels of diastolic blood pressure, triglycerides and high‐density lipoprotein cholesterol, after adjusting for covariates. Age and hypertension were the common risk factors for increased CIMT in all three groups. Furthermore, male sex, smoking and high low‐density lipoprotein cholesterol level were positively associated with the mean CIMT in the normal group; high triglycerides levels were negatively associated with the mean CIMT in the impaired fasting glucose group; and alcohol consumption was an independent risk factor for mean CIMT in the diabetes mellitus group. Hypertension was the greatest risk factor for increased CIMT.

Conclusions

These findings suggest that it is crucial to manage and control traditional risk factors in low‐income populations in China in order to decelerate the recent dramatic increase in stroke incidence, and to reduce the burden of stroke.

Molecular Analysis of a Genetic Variants Panel Related to Nutrients and Metabolism: Association with Susceptibility to Gestational Diabetes and Cardiometabolic Risk in Affected Women

Gestational diabetes mellitus (GDM) is the most frequent metabolic disorder in pregnancy. Women with a GDM history are at increased risk of developing diabetes and cardiovascular diseases. Studies have demonstrated a significant correlation between several genes involved in the metabolic pathway of insulin and environmental factors. The aim of this study was to investigate the relationship between clinical parameters in GDM and variants in genes involved with nutrients and metabolism. Several variants PPARG2 rs1801282 (C>G); PPARGC1A rs8192678 (C>T); TCF7L2 rs7903146 (C>T); LDLR rs2228671 (C>T); MTHFR rs1801133 (C>T); APOA5 rs662799 (T>C); GCKR rs1260326 (C>T); FTO rs9939609 (T>A); MC4R rs17782313 (T>C) were genotyped in 168 pregnant Caucasian women with or without GDM by High Resolution Melting (HRM) analysis. A significant correlation was observed between TT genotype of TCF7L2 gene and increased risk of GDM (OR 5.4 [95% CI 1.5-19.3]). Moreover, a significant correlation was observed between lipid parameters and genetic variations in additional genes, namely, PPARG2 [p = 0,02], APOA5 [p = 0,02], MC4R [p = 0,03], LDLR [p = 0,01], and FTO [p = 0,02]. Our findings support the association between TCF7L2 rs7903146 variant and an increased GDM risk. Results about the investigated genetic variants provide important information about cardiometabolic risk in GDM and help to plan future prevention studies.

Assessment of epicardial adipose tissue and carotid/femoral intima media thickness in insulin resistance

BACKGROUND

Metabolic syndrome is a combination of multiple cardiovascular (CV) risk factors including insulin resistance (IR). Carotid, femoral intima media thickness (IMT), and epicardial fat thickness (EFT) are considered as novel cardiometabolic risk factors. We aimed to test the hypothesis that carotid, femoral IMT, and EFT are increased in patients with IR.

METHODS

We enrolled consecutively and prospectively 113 patients with IR. Then we collected data from an age- and sex-matched control group of 112 individuals without IR. Homeostasis model assessment (HOMA) index value >2.5 was accepted as IR. Patients with diabetes mellitus, CV diseases, systolic heart failure, chronic liver or renal diseases were excluded. On B-mode duplex ultrasound the mean IMT at the far wall of both left and right common carotid/femoral arteries were measured manually. EFT was measured on the free wall of the right ventricle at end-diastole from the parasternal long-axis views by standard transthoracic 2D echocardiography.

RESULTS

Both carotid IMT and EFT were significantly higher in patients with IR compared to controls (0.80±0.21mm vs 0.60±0.21mm; p<0.001 and 7.34±1.96mm vs 5.22±1.75mm; p<0.001, respectively). However, there were no significant differences in femoral IMT between the groups (0.74±0.20 vs 0.69±0.17; p=0.062). In multivariate linear regression analysis age (β=0.223, p=0.010), 2-h blood glucose (β=0.198, p=0.021), and IR (β=0.369, p<0.001) were independent predictors of EFT. On the other hand age (β=0.363, p<0.001) and IR (β=0.321, p<0.001) were independent predictors of carotid IMT.

CONCLUSIONS

Patients with IR have increased carotid IMT and EFT, but not femoral IMT. This apparent incoherence may be due to the involvement of carotid arteries prior to femoral arteries in patients with IR.

Increased carotid intima-media thickness in the physiologic range is associated with impaired postprandial glucose metabolism, insulin resistance and beta cell dysfunction

BACKGROUND

Carotid Intima-Media Thickness (C-IMT) is a reliable predictor of cardiovascular events. We examined if increased C-IMT was associated with defects in glucose metabolism in non-diabetic subjects independently of age.

METHODS

In 366 Caucasian non-diabetic subjects of the CARAMERIS study, we measured glucose response during a 75 g-Oral Glucose Tolerance Test (OGTT), insulin sensitivity index (ISI, by Matsuda Index), Liver Insulin Resistance Index (Liver-IR), insulin secretion by ΔAUC Ins0-120/Glu0-120 (ΔI/ΔG) and beta cell function (Disposition Index, DI).

RESULTS

Subjects were divided in two groups according to the median age (AGE1 ≤ 45 y; AGE2 > 45 y). Only 5 subjects in AGE1 and 32 in AGE2 had C-IMT > 0.9 mm. Compared to AGE1, AGE2 had a worse cardio-metabolic profile, increased cholesterol, glucose and insulin concentrations, blood pressure and C-IMT. Both ΔI/ΔG ratio and DI were significantly reduced in AGE2. By considering tertiles of C-IMT in each AGE group (G1-G3, where G3 comprised the highest C-IMT), we found that G3 showed increased OGTT glucose profiles and Liver IR, decreased ISI and DI, compared to G1 in each AGE group.

CONCLUSIONS

Increased C-IMT, but within normal ranges, is associated independently of age with altered postprandial glucose profile, increased peripheral and hepatic insulin resistance, decreased b-cell function. C-IMT measurement should become a routine analysis even in younger subjects to predict the risk of cardio-metabolic disease.

Early signs of atherosclerosis are associated with insulin resistance in non-obese adolescent and young adults with type 1 diabetes

Background

Patients with type 1 diabetes have a substantial risk of developing cardiovascular complications early in life. We aimed to explore the role of insulin sensitivity (S_i) as an early factor of atherosclerosis in young type 1 diabetes vs. non-diabetic subjects.

Methods

Forty adolescent and young adult individuals (20 type 1 diabetics and 20 non-diabetics), age 14–20 years, without characteristics of the metabolic syndrome, participated in this cross-sectional study. After an overnight fast, S_i was measured by hyperinsulinemic euglycemic clamp (40 mU/m²) and calculated by glucose infusion rate (GIR). Carotid intima-media thickness (cIMT) was measured in the common carotid artery with high-resolution ultrasonography. Risk factors of atherosclerosis (Body mass index [BMI], waist circumference, systolic blood pressure [sBP], triglycerides, low HDL-cholesterol and HbA_1c) were also investigated.

Results

cIMT was increased (0.52 ± 0.1 vs. 0.47 ± 0.1 mm, P < 0.01), whereas GIR was decreased (5.0 ± 2.1 vs. 7.1 ± 2.2 mg/kg/min, P < 0.01) in type 1 diabetics vs. non-diabetics. The differences in cIMT were negatively associated with S_i (r = −0.4, P < 0.01) and positively associated with waist circumference (r = 0.34, P = 0.03), with no such associations between BMI (r = 0.15, P = 0.32), sBP (r = 0.09, P = 0.58), triglycerides (r = 0.07, P = 0.66), HDL-cholesterol (r = 0.10, P = 0.55) and HbA_1c (r = 0.24, P = 0.13). In a multivariate regression model, between cIMT (dependent) and group (explanatory), only adjustment for S_i affected the significance (ß = 0.08, P = 0.11) vs. (ß = 0.07, P < 0.01) for the whole model. No interaction between cIMT, groups and S_i was observed.

Conclusions

cIMT is increased and associated with insulin resistance in adolescent, non-obese type 1 diabetic subjects. Although, no conclusions toward a causal relationship can be drawn from current findings, insulin resistance emerges as an important factor reflecting early signs of atherosclerosis in this small cohort.

Differential impact of heart rate on arterial wall stiffness and thickness in young adults: The Bogalusa Heart Study

Heart rate, a hemodynamic parameter, is an important determinant of arterial wall stiffness. However, information on the relationship of heart rate to arterial wall thickness is inconsistent. This study examined the influence of heart rate on arterial stiffness and thickness in Black and White young adults. The study cohort consisted of 255 Black and 659 White adults age 25 to 43 years enrolled in the Bogalusa Heart Study. Carotid artery intima-media thickness (IMT) was measured by B-mode ultrasound and aorta-femoral pulse wave velocity (af-PWV) by echo-Doppler. There was no difference in heart rate between Blacks and Whites. Males vs. females displayed lower heart rate and higher segmental and composite carotid IMT; Blacks vs. Whites had higher composite carotid IMT (0.83 mm vs. 0.80 mm, P < .01) and af-PWV (5.4 m/s vs. 5.2 m/s, P < .01). In a multivariate regression model adjusting for traditional cardiovascular risk variables, heart rate was independently associated with af-PWV (standardized regression coefficient: beta = .14, P = .01 for Blacks; beta = .06, P = .07 for Whites; beta = .09, P = .003 for total sample), but not with carotid IMT. These results indicate that heart rate plays differential roles in the development of arterial stiffness and subclinical atherosclerosis during young adulthood.

Do obese patients after weight loss become metabolically normal?

OBJECTIVE

To compare the metabolic cardiovascular risk factors of obese patients after weight loss and 4-year weight loss maintenance afterwards against a matched control group of subjects with a stable body weight and without history of weight loss.

METHOD

50 obese non-diabetic subjects in the study group who previously lost 10% or more of their weight and afterwards entered a 4-year weight loss maintenance programme were matched by age, BMI and sex and compared to 50 weight-stable subjects without history of weight loss. The comparison between both groups was done in term of anthropometrical, metabolic and biological characteristics, early atherosclerosis and insulin sensitivity.

RESULTS

Anthropometrical, metabolic and biological characteristics were similar between the weight loss group and the control matched group. However, insulin sensitivity was still significantly lower in the weight loss than in the matched control group (p = 0.02). Intima media thickness (IMT) also was similar in both groups. We found that lower atherosclerosis measured by IMT at the level of the carotid is associated with better insulin sensitivity (p < 0.05). After the 4-year weight loss maintenance programme, insulin sensitivity improved in the post-weight loss group from 7.9 ± 3.2 to 8.4 ± 3.6 mg/kg/min.

CONCLUSION

All cardiometabolic parameters of obese subjects, except for insulin sensitivity, normalised completely after weight loss. The latter was improved by a weight loss maintenance programme if successfully completed.

Erythrocyte sodium-lithium countertransport activity is inversely correlated to adiponectin, retinol binding protein 4 and body height

BACKGROUND

We have previously described that the sodium/lithium countertransport (SLC) in the erythrocyte cell membrane is closely linked to obesity and insulin resistance. Adiponectin and retinol-binding protein 4 (RBP-4) are believed to affect obesity and insulin resistance. In the present study, we aimed to further characterize the relationship between SLC, inflammatory markers, adiponectin and RBP-4.

METHODS

We included 93 clinically healthy 58-year-old men selected to display variations in insulin sensitivity. High sensitivity C-reactive protein (hs-CRP), TNF-alpha, soluble TNF-alpha-receptors (sTNFR) 1 and 2, IL-6 and RBP-4 were measured using antibody-based techniques. Adiponectin was determined by a radioimmunoassay kit. The lithium concentration in the special flux medium was measured by atomic absorption spectrophotometry.

RESULTS

In univariate analyses, SLC correlated negatively with RBP-4 (r(s) = -0.256, p = -0.017) and to adiponectin (r(s) = -0.316, p = 0.003) and positively with TNF-alpha (r(s) = 0.346, p = 0.001) and hs-CRP (r(s) = 0.288, p = 0.005). There were no statistically significant correlations with sTNFR 1 or 2 or IL-6. SLC was negatively associated to body height (r(s) = -0.256, p = 0.013).

CONCLUSIONS

We are the first to report that SLC correlates negatively with adiponectin and RBP-4. This finding is intriguing, as adiponectin is anti-inflammatory and anti-diabetic whereas RBP-4 supposedly decreases insulin sensitivity. We also observed a negative association between SLC activity and body height indicating that SLC activity is not primarily influenced by fat mass. The positive association of SLC with markers of inflammatory activity such as TNF-alpha and hs-CRP is in line with the proposed link between inflammation and insulin resistance.

Atherogenic dyslipidemia and oxidative stress: a new look

Although results from in vitro studies and clinical trials demonstrate strong associations between oxidative stress and cardiovascular risk, to date still no convincing data are available to suggest that treatment with antioxidants might reduce vascular events. Oxidative modifications of low-density lipoproteins (LDL) represent an early stage of atherosclerosis, and small, dense LDL are more susceptible to oxidation than larger, more buoyant particles. Oxidized LDL are independent predictors of subclinical and clinical atherosclerosis. Recent studies suggested that novel therapeutic strategies may take into account the removal of such particles from circulation. Future research is required to explore the potential synergistic impact of markers of oxidative stress and atherogenic dyslipidemia, particularly small dense LDL, on cardiovascular risk.

Albuminuria within the normal range and ultrasound-assessed atherosclerosis in the AIR study: a 9-year follow-up of 58-year-old clinically healthy men

BACKGROUND

Microalbuminuria, traditionally defined as 30-300 mg urinary albumin/24 h, predicts renal impairment and cardiovascular disease. Studies suggest that also a far lower urinary albumin excretion (UAE) can predict clinical outcome. Intima media thickness (IMT) is an established estimate of atherosclerosis. In this study, we investigated the predictive value of UAE within the normal rate (UAE-n) for the progression of IMT in the carotid and femoral arteries.

METHODS

We included 325 clinically healthy men with normoalbuminuria. Anthropometrics, urine and blood samples were taken and IMT in the carotid and femoral arteries were assessed by B-mode ultrasound at baseline and after 3 and 9 years. The annual progression rate of IMT (r-IMT) was calculated.

RESULTS

UAE-n correlated with carotid IMT at baseline and after 3 and 9 years, but not with r-IMT. In a regression analysis, only HDL and baseline IMT remained as statistically significant co-variates to mean IMT at 9 years. IMT in the femoral artery and r-IMT at any time-point did not correlate to baseline UAE.

CONCLUSION

UAE-n was associated with carotid IMT after 3 and 9 years but not r-IMT or with femoral artery IMT. Carotid IMT after 9 years' follow-up was independently related to baseline IMT and HDL cholesterol. In this cohort of 58-year-old men, our interpretation is that UAE-n is not associated with the increase in carotid and femoral artery IMT observed after 9 years.

Glucose turnover and intima media thickness of internal carotid artery in type 2 diabetes offspring

BACKGROUND

First-degree offspring (OFF) of type 2 diabetic (T2DM) patients bear a approximately 40% lifetime risk of developing T2DM. They are insulin resistant and carry a risk of premature atherosclerosis, the extent of which can be estimated by intima media thickness (IMT) of the carotid artery (CA). Thus, this study examines parameters of glucose and lipid metabolism, insulin sensitivity, beta cell function (BCF) and IMT with their interrelationships in middle-aged OFF.

MATERIALS AND METHODS

T2DM-OFF (n = 18, 14f/4m, 45.6 +/- 2.1 years, BMI: 26 +/- 1 kg m(-2)) were compared with 18 matching humans without a family history of diabetes (CON; 14f/4m, 44.5 +/- 2.1 years, BMI: 24 +/- 1 kg m(-2); each P > 0.30), all with normal glucose tolerance as tested by three-hour (75 g) oral glucose tolerance tests (OGTT). Two-hour hyperinsulinaemic (40 mU min(-1).m(-2))isoglycaemic clamp tests were performed with simultaneous measurement of endogenous glucose (D-[6,6-(2)H(2)]glucose) production (EGP). IMT [internal (ICA), common CA, and bulb] were measured sonographically. BCF was assessed by Adaptation Index (AI).

RESULTS

Before and during OGTT, both groups were similar in plasma glucose, insulin, C-peptide and free fatty acids (FFA), whereas OFF showed ~30% lower (P < 0.03) fasting plasma triglycerides before OGTT. During hyperinsulinaemic clamps, insulin sensitivity was approximately 38% lower (P < 0.03) in OFF who showed higher plasma FFA (44 +/- 9 micromol L(-1)) than CON (26 +/- 3 micromol L(-1), P < 0.05) after 90 min. EGP was similar in both groups. OFF had 38% (P < 0.007) reduced AI. ICA-IMT was approximately 18% higher in OFF (P < 0.002), but did not correlate with insulin sensitivity.

CONCLUSION

The data obtained show middle-aged T2DM-OFF with normal glucose tolerance displaying reduced total insulin sensitivity and impaired beta cell function, which relates to impaired insulin-dependent suppression of plasma FFA and increased ICA-IMT.

Carotid artery intima-media thickness in nonalcoholic fatty liver disease

PURPOSE

To evaluate, in patients with nonalcoholic fatty liver disease with no or mild alterations of liver function tests, carotid artery intima-media thickness and the presence of plaques and to define determinants of vascular damage.

METHODS

A paired-sample case-control study: 125 patients with nonalcoholic fatty liver disease and 250 controls, without a prior diagnosis of diabetes, hypertension, and cardiovascular disease, matched for sex, age, and body mass index. B-mode ultrasound was used for evaluation of carotid intima-media thickness and presence of small plaques.

RESULTS

A significant difference in mean values of intima-media thickness (0.89+/-0.26 and 0.64+/-0.14 mm, P = .0001) and prevalence of plaques (26 [21%] and 15 [6%], P < .001) was observed in nonalcoholic fatty liver disease patients and controls. Variables significantly associated with intima-media thickness higher than 0.64 mm (median value in controls), in both patients and controls were: age (P = .0001), systolic blood pressure (P = .004), total and low-density lipoprotein cholesterol (P < or = .02 and P = .01, respectively), fasting glucose (P = .0001), and cardiovascular risk (P = .0001) and, only in controls, metabolic syndrome (P = .0001), HOMA-insulin resistance (P = .01), and body mass index (P = .0003). At multivariate logistic regression performed in the overall series of subjects, independent risk predictors of intima-media thickness higher than 0.64 mm were presence of steatosis (odds ratio [OR] = 6.9), age (OR 6.0), and systolic blood pressure (OR 2.3).

CONCLUSION

Patients with nonalcoholic fatty liver disease, even with no or mild alterations of liver tests, should be considered at high risk for cardiovascular complications.

Who needs to care about small, dense low-density lipoproteins?

BACKGROUND

Increasing evidence suggest that the 'quality' rather than only the 'quantity' of low-density lipoprotein (LDL) exerts a great influence on the cardiovascular risk. Small, dense LDL seem to be an important predictor of cardiovascular events and progression of coronary artery disease (CAD) and their predominance has been accepted as an emerging cardiovascular risk factor by the National Cholesterol Education Program Adult Treatment Panel III.

DISCUSSION

Some studies showed in past years that small, dense LDL are usually elevated in patients at very high cardiovascular risk, such as those with CAD and type 2 diabetes. More recently elevated levels of these particles have been found in other categories of patients at high cardiovascular risk, such as those with non-coronary forms of atherosclerosis (e.g. with carotid artery disease, aortic abdominal aneurysm and peripheral arterial disease) and metabolic diseases (with polycystic ovary syndrome and growth hormone deficiency); notably, in most of them, the predominance of small, dense LDL characterised their type of dyslipidaemia, alone or in combination with elevated triglycerides and reduced high-density lipoproteins cholesterol concentrations.

CONCLUSIONS

The therapeutical modulation of small, dense LDL have been shown to significantly reduce cardiovascular risk and weight reduction and increased physical activity may constitute first-line therapy. In addition, lipid-lowering drugs are able to favourably alter these particles and fibrates and nicotinic acid seem to be the most effective agents. Promising data are also available with the use of rosuvastatin, the latest statin introduced in the market, and ezetimibe, a cholesterol absorption inhibitor.

Carotid artery intima media thickness is inversely related to serum free thyroxine in euthyroid subjects

OBJECTIVE

The effect of thyroid function on cardiovascular risk may extend to the euthyroid range. In euthyroid subjects, we determined whether carotid artery intima media thickness (IMT), a measure of subclinical atherosclerosis, is related to thyroid function.

DESIGN AND SUBJECTS

Cross-sectional study in a cohort of 78 nonsmoking, predominantly middle-aged, euthyroid subjects (44 men and 34 women, mean age 56 years, TSH between 0.5 mU/l and 4.0 mU/l and FT4 between 11.0 pmol/l and 19.5 pmol/l).

MEASUREMENTS

IMT (mean of three segments in both carotid arteries by ultrasonography), clinical factors, insulin resistance (HOMA(ir)), plasma lipids, C-reactive protein (CRP), serum FT4, TSH and thyroid autoantibodies.

RESULTS

In several multiple linear regression models, age- and sex-adjusted IMT was found to be independently related to either pulse pressure and body mass index (BMI), to high density lipoprotein (HDL) cholesterol or to FT4, but not to TSH, thyroid autoantibodies, HOMA(ir), CRP, non-HDL cholesterol and triglycerides. In a subsequent model which included age, sex, pulse pressure, body mass index (BMI), HDL cholesterol and FT4, IMT was independently and positively related to age (beta = 0.43, P < 0.001), male sex (beta = 0.34, P = 0.014), pulse pressure (beta = 0.29, P = 0.002), BMI (beta = 0.24, P = 0.007) and inversely related to FT4 (beta = -0.19, P = 0.046). IMT was also inversely related to FT4 in a model which included HDL cholesterol, non-HDL cholesterol and triglycerides.

CONCLUSIONS

In euthyroid subjects, IMT is associated with FT(4), after controlling for clinical factors, lipid levels and thyroid autoantibodies. These findings raise the possibility that, even within the euthyroid range, low normal thyroid function may adversely affect cardiovascular risk.

Insulin resistance, metabolic syndrome, and subclinical atherosclerosis: the Multi-Ethnic Study of Atherosclerosis (MESA)

OBJECTIVE

To investigate the association of insulin resistance and clinically defined metabolic syndrome (MetS) with subclinical atherosclerosis and examine whether these relationships vary by race/ethnicity or sex.

RESEARCH DESIGN AND METHODS

Subclinical atherosclerosis was assessed by coronary artery calcium (CAC) and carotid intima-medial thickness (IMT) in 5,810 participants without diabetes in the Multi-Ethnic Study of Atherosclerosis, a cohort of adults aged 45-84 years without prior cardiovascular disease (CVD). Fasting insulin and glucose were utilized to estimate insulin resistance by the homeostasis model assessment of insulin resistance (HOMA-IR) index, and the revised National Cholesterol Education Program definition of MetS was utilized. Multivariable linear or relative risk regression was used to analyze the association between HOMA-IR and subclinical atherosclerosis and assess its independence from MetS components.

RESULTS

HOMA-IR was associated with increased IMT after adjustment for demographics (age, site, and education), smoking, education, and LDL cholesterol in each ethnic group, except Hispanic subjects, and in both men and women. After further adjusting for nonglucose MetS components, HOMA-IR was not associated with increased IMT. Subjects in the highest quintile of HOMA-IR had an elevated prevalence of CAC in each ethnic group and both sexes, after adjustment for demographics, smoking, and LDL but not after further adjustment for nonglucose MetS components. Among those with detectable CAC, there was no significant relationship between HOMA-IR and the amount of CAC.

CONCLUSIONS

Although HOMA-IR was associated with increased subclinical atherosclerosis, the association was not independent of the risk factors that comprise MetS. Determination of HOMA-IR is unlikely to contribute to improved determination of risk of subclinical CVD.

Patients at high risk for ischemic stroke: identification and actions

Atherosclerosis is a disease of chronic inflammation. It is diffuse, multisystemic and affects the vascular, metabolic and immune systems. The traditional evaluation of risk is based on methods of clinical and biological assessments, and conventional imaging. The existence of symptomatic disease and the number of symptomatic sites of atherothrombosis are critical factors in predicting the recurrence of major vascular events. However, these methods are insufficient to predict near-future episodes, above all in the individual standard clinical practice. Active treatment of modifiable risk factors such as hypertension, dyslipidemia and atrial fibrillation can reduce the number of patients who develop a stroke. There is considerable evidence suggesting that a substantial proportion of the population with high blood pressure receives insufficient treatment. More active treatment of this condition is probably the most efficient single measure. Lifestyle factors such as smoking, diet, physical inactivity and obesity contribute to the relatively high incidence of stroke. There is a need to incorporate new systemic markers and new investigation techniques in the future so as to identify the individuals at risk in the population and to administer more individualized intervention therapies.

High-density lipoprotein-cholesterol and risk of stroke and carotid atherosclerosis: a systematic review

BACKGROUND AND PURPOSE

Epidemiological studies have found no relationship between total cholesterol and stroke risk, but little attention has been paid to high-density lipoprotein-cholesterol (HDL-C).

METHODS

We performed a systematic PubMed literature search for epidemiological studies that examined the association between HDL-C level and stroke or carotid intima-media thickness (IMT).

RESULTS

We identified 18 studies on the relationship between HDL-C and stroke risk and 37 on HDL-C and carotid IMT. Eight of ten prospective cohort studies (n=238,739) and three of eight case-control studies (n=3604 cases, 8220 controls) supported an association between elevated HDL-C level and decreased risk of stroke. Prospective cohort studies reporting on relative risk per unit increase in HDL-C showed an 11-15% decreased stroke risk per 10-mg/dl increase in HDL-C. Of 37 studies on carotid IMT, 31 reported cross-sectional, one longitudinal, and five both cross-sectional and longitudinal associations between HDL-C level and carotid IMT. Of 36 cross-sectional studies (n=51,288), 20 showed an inverse association between HDL-C level and carotid IMT. Of six longitudinal studies (n=20,065), three showed no association, one showed a weak association in a subgroup of white women and two showed a significant inverse relationship between HDL-C level and carotid IMT. Pooled estimates could not be calculated because of the variation in study designs and analysis.

CONCLUSIONS

The weight of evidence in the literature supports an inverse association between HDL-C level and stroke or carotid atherosclerosis, but more data are needed to firmly establish this protective effect.

Small, dense low-density-lipoproteins and the metabolic syndrome

Small, dense low-density-lipoproteins (LDL) are associated with increased risk for cardiovascular diseases and diabetes mellitus and a reduction in LDL size has been reported in patients with coronary and non-coronary forms of atherosclerosis. LDL size has been accepted as an important predictor of cardiovascular events and progression of coronary artery disease as well as an emerging cardiovascular risk factor by the National Cholesterol Education Program Adult Treatment Panel III. Small, dense LDL, with elevated triglyceride levels and low HDL-cholesterol concentrations, constitute the 'atherogenic lipoprotein phenotype (ALP)', a form of atherogenic dyslipidemia that is a feature of type 2 diabetes and the metabolic syndrome. LDL size and subclasses show specific alterations in patients with the metabolic syndrome that probably significantly increase their cardiovascular risk; however, so far it has not been recommended to incorporate LDL size measurements in treatment plans, when hypolipidemic therapies are installed. Patients with type 2 diabetes are at high cardiovascular risk and it is still on debate if the treatment goals may be identical or whether there are distinct groups with different cardiovascular risks and hence with different treatment goals. Measurements beyond traditional lipids, such as measurements on the presence of small, dense LDL in patients with the metabolic syndrome, may help to identify cardiovascular risk subgroups. In addition, it might be possible in the future to individualize hypolipidemic treatments if more than the traditional lipids are taken into account. LDL size measurement may potentially help to assess cardiovascular risk within the metabolic syndrome and adapt the treatment goals thereafter.

Circulating estradiol is an independent predictor of progression of carotid artery intima-media thickness in middle-aged men

CONTEXT

Estrogen treatment of men with prostate cancer is associated with increased cardiovascular morbidity and mortality; however, the role of endogenous estrogen levels for atherosclerotic disease in men is unknown.

OBJECTIVE

The objective of the study was to determine whether endogenous serum estradiol (E2) levels predict the progression of carotid artery intima-media thickness in men.

DESIGN, SETTING AND PARTICIPANTS

This was a population-based, prospective cohort study (the Atherosclerosis and Insulin Resistance study) conducted in Göteborg, Sweden, among 313 Caucasian men without cardiovascular or other clinically overt diseases. Carotid artery intima-media thickness, an index of preclinical atherosclerosis, was measured by ultrasound at baseline (58 yr of age) and after 3 yr of follow-up. Serum sex hormone levels and cardiovascular risk factors (body mass index, waist to hip ratio, systolic blood pressure, serum triglycerides, plasma c-peptide, and smoking status) were assessed at study entry.

INTERVENTION

There was no intervention.

MAIN OUTCOME MEASURES

Association between baseline total and free E2 levels and progression of carotid intima-media thickness over 3 yr with adjustments for cardiovascular risk factors was measured.

RESULTS

In univariate analyses, both total and free E2 levels at baseline were positively associated with the annual change in intima-media thickness. In linear regression models including E2 and cardiovascular risk factors, low-density lipoprotein and high-density lipoprotein cholesterol and E2 were identified as independent predictors of progression of carotid artery intima-media thickness (total E2 beta = 0.187, P = 0.001; and free E2 beta = 0.183, P = 0.003).

CONCLUSIONS

Circulating E2 is a predictor of progression of carotid artery intima-media thickness in middle-aged men. Further studies are needed to investigate the role of endogenous E2 for incident cardiovascular disease events.

Low-density lipoprotein size and cardiovascular prevention

Low-density lipoprotein (LDL) size appears to be an important predictor of cardiovascular events and progression of coronary artery disease, and the predominance of small, dense LDL has been accepted as an emerging cardiovascular risk factor by the National Cholesterol Education Program Adult Treatment Panel III. Yet, other authors have suggested that LDL subclass measurement does not add independent information to that conferred generically by LDL concentration and other standard risk factors. Therefore, the debate continues as to whether to measure LDL particle size for cardiovascular prevention and, if so, in which categories of patients. Since the therapeutic modulation of distinct LDL subspecies is of great benefit in reducing the risk of cardiovascular events, LDL size measurement should be extended as much as possible to patients at high risk of cardiovascular diseases.

Asymptomatic cerebrovascular disease and systemic diagnosis in stroke, atherothrombosis as a disease of the vascular tree

Atherosclerosis is a chronic vascular disease of true epidemic proportions. It is the first cause of death in developed countries and responsible for one quarter of documented deaths worldwide. Arteriosclerotic vascular disease is a systemic process which affects different organs; principally the heart, brain, and peripheral artery system. Despite well-documented differences, all manifestations of the disease share the same risk factors; albeit with varying degrees of impact. The concept of asymptomatic cerebrovascular disease is an important one for clinicians who treat stroke patients. The development of new neuroimaging and vascular evaluation techniques has enabled the presence of apparently silent lesions to be detected and their progress monitored in follow-up. Ultrasonography techniques enable the identification of atheromatous disease. Asymptomatic involvement of the cerebral parenchyma consists of ischemia, leukoaraiosis, and silent hemorrhage and can be detected using the available radiological techniques such as cranial CT, magnetic resonance, or gradient echo magnetic resonance imaging. From the point of view of prevention, it is of considerable importance to identify diagnostic markers for arteriosclerosis in asymptomatic patients in some, if not all, vascular territories. In view of the natural history of this disease and the impact it has on society, there is an increasing need to identify and understand the risk factors or vascular disease risk markers, so that the stratification of risk of an individual patient or in a specific population can be established, appropriate cerebrovascular assessments conducted, and appropriate therapeutic intervention initiated.

Correlation of Coronary and Cerebral Atherosclerosis: Difference between Extracranial and Intracranial Arteries

BACKGROUND

A difference with regard to the correlation with coronary atherosclerosis (CAS) between extracranial carotid atherosclerosis (ECAS) and intracranial cerebral atherosclerosis (ICAS) has been assumed but not proven clearly by direct comparison within the same population.

METHODS

A consecutive series of 246 patients undergoing coronary artery bypass graft surgery were reviewed. The severity of CAS was estimated as a CAS score based on coronary angiography. The presence of ECAS and ICAS was screened by transcranial Doppler and carotid duplex sonography, and confirmed by magnetic resonance angiography.

RESULTS

The CAS scores in patients with ECAS were observed to be higher than those in patients without ECAS (10.62+/- 4.80 vs. 9.45+/- 4.25; p=0.054 on the Mann-Whitney U test). The difference in CAS scores was smaller between patients with and without ICAS (10.41+/- 4.44 vs. 9.66+/- 4.49; p=0.201). Similar patterns were observed on comparing the correlation of ECAS and ICAS with a quartile of the CAS score. An advanced CAS, which was generated by collapsing the quartiles of the CAS score into 75th percentile or less and more than the 75th percentile, was significantly associated with ECAS, but not with ICAS. These associations remained unchanged after adjustments had been made for age, sex, hypertension, diabetes mellitus, hyperlipidemia, smoking and a history of stroke or transient ischemic attack.

CONCLUSIONS

This study suggests that the correlation of CAS with ECAS is stronger than that of CAS with ICAS, and this difference is independent of the classic risk factors for atherosclerosis.

Low-density lipoprotein size and cardiovascular risk assessment

A predominance of small, dense low-density lipoproteins (LDL) has been accepted as an emerging cardiovascular risk factor by the National Cholesterol Education Program Adult Treatment Panel III. LDL size seems to be an important predictor of cardiovascular events and progression of coronary heart disease and evidences suggests that both quality (particularly small, dense LDL) and quantity may increase cardiovascular risk. However, other authors have suggested that LDL size measurement does not add information beyond that obtained by measuring LDL concentration, triglyceride levels and HDL concentrations. Therefore, it remains debatable whether to measure LDL particle size in cardiovascular risk assessment and, if so, in which categories of patient. Therapeutic modulation of LDL particle size or number appears beneficial in reducing the risk of cardiovascular events, but no clear causal relationship has been shown, because of confounding factors, including lipid and non-lipid variables. Studies are needed to investigate the clinical significance of LDL size measurements in patients with coronary and non-coronary forms of atherosclerosis; in particular, to test whether LDL size is associated with even higher vascular risk, and whether LDL size modification may contribute to secondary prevention in such patients.

Fatty Acids Cause Alterations of Human Arterial Smooth Muscle Cell Proteoglycans That Increase the Affinity for Low-Density Lipoprotein

Objective— The dyslipidemia of insulin resistance, with high levels of albumin-bound fatty acids, is a strong cardiovascular disease risk. Human arterial smooth muscle cell (hASMC) matrix proteoglycans (PGs) contribute to the retention of apoB lipoproteins in the intima, a possible key step in atherogenesis. We investigated the effects of high NEFA levels on the PGs secreted by hASMCs and whether these effects might alter the PG affinity for low-density lipoprotein.

Methods and Results— hASMC exposed for 72 hours to high concentrations (800 μmol/L) of linoleate (LO) or palmitate upregulated the core protein mRNAs of the major PGs, as measured by quantitative PCR. Insulin (1 nmol/L) and the PPARγ agonist rosiglitazone (10 μmol/L) blocked these effects. In addition, high LO increased the mRNA levels of enzymes required for glycosaminoglycan (GAG) synthesis. Exposure to NEFA increased the chondroitin sulfate:heparan sulfate ratio and the negative charge of the PGs. Because of these changes, the GAGs secreted by LO-treated cells had a higher affinity for human low-density lipoprotein than GAGs from control cells. Insulin and rosiglitazone inhibited this increase in affinity.

Conclusions— The response of hASMC to NEFA could induce extracellular matrix alterations favoring apoB lipoprotein deposition and atherogenesis.

[Influence of orlistat therapy on serum insulin level and morphological and functional parameters of peripheral arterial circulation in obese patients]

BACKGROUND/AIM

Insulin resistance is related to accelerated atherosclerosis, whereas weight loss is associated with the increasing insulin sensitivity, the improvement of functional and the morphological parameters of arterial circulation, and the reduction of cardiovascular morbidity and mortality. The aim of our study was to evaluate the influence of orlistat treatment on serum insulin level and functional and morphologic parameters of peripheral arterial circulation.

METHODS

We conducted a prospective, randomized, double - blind, placebo - controlled study. Thirty patients with body mass index over 30 kg/m2 normotensive, nonsmokers, without clinically manifested cardiovascular disease or diabetes were randomly assigned either orlistat (120 mg, 3 times daily; n = 20) or placebo (n = 10) in a double - blind manner. All of the patients were on individually calculated hypocaloric diet. The follow-up period was 24 weeks. Arterial pressure, fasting serum glucose and insulin level, triglycerides, total cholesterol and low density lipoprotein-cholesterol were determined at the beginning, following 3 and 6 months. Also, the intima - media thickness of right superficial femoral artery and the mean blood flow velocity were determined with ultrasonography.

RESULTS

Inside the period of 3 and 6 months, there were the greater reductions of body mass index, arterial pressure, fasting glucose and insulin level, total cholesterol, low density lipoproteins, as well as the greater reductions of mean velocity blood flow and peripheral pulse pressure in the orlistat group vs the placebo group (p < 0.01). Greater reductions in the waist circumference and intima - media thickness were registered following 6 months in the orlistat vs the placebo group (p < 0.01).

CONCLUSION

In the group of obese patients orlistat therapy reduced risk factors, serum insulin level and improved early arterial functional changes as assessed with the reductions of the mean velocity blood flow and peripheral pulse pressure following 3 months. The regression of morphological changes, as assessed with the reduction in intima - media thickness, was feasible over the six - month period.

The reciprocal association of adipocytokines with insulin resistance and C-reactive protein in clinically healthy men

In experimental models, adiponectin improves and tumor necrosis factor alpha (TNF- alpha ) impairs insulin action, and the expression of these adipocytokines seems to have a reciprocal regulation. The aim was to examine whether in a cross-sectional study, associations supporting this concept may be found in 58-year-old clinically healthy men, and also the relation to C-reactive protein (CRP). In 102 men, euglycemic hyperinsulinemic clamp was used to assess glucose infusion rate (GIR). Total body fat (dual-energy x-ray absorptiometry), plasma adiponectin (radioimmunoassay), TNF-alpha , and CRP (enzyme-linked immunosorbent assay) were measured. Adiponectin correlated positively to GIR (r=0.33, P<.001) and negatively to total fat mass (r=-0.29, P=.004), whereas TNF- alpha showed reverse associations (r=-0.31, P<.01, and r=0.31, P<.01). Adiponectin and TNF- alpha were negatively correlated (-0.28, P=.006). An interaction term (TNF- alpha /adiponectin ratio) and body fat together explained 31.3% (P<.001) in GIR variability. The odds ratio for having insulin resistance was 9.3 (95% CI, 2.2-38.9) in subjects with TNF-alpha values above and adiponectin levels below the median, as compared to subjects with TNF- alpha values below and adiponectin levels above the median. Total fat and TNF-alpha , but not adiponectin, were significantly associated with log CRP (R2=20%, P<.001). In conclusion, this study in man showed that plasma adiponectin and TNF-alpha were independently and reversely associated with insulin resistance. C-reactive protein levels were related to TNF-alpha and obesity.

Asymmetric dimethylarginine: A molecule responsible for the coexistence of insulin resistance and atherosclerosis via dual nitric oxide synthase inhibition

Asymmetric dimethylarginine (ADMA) has been recently identified as the major endogenous inhibitor of soluble nitric oxide synthase. Its systemic accumulation was observed in conjunction with atherosclerosis and several cardiovascular and metabolic diseases. Here, we propose that ADMA causes insulin resistance by the inhibition of the neuronal isoform of nitric oxide synthase, while the simultaneously observed atherosclerosis is the consequence of endothelial nitric oxide synthase (NOS) inhibition. Our hypothesis rests on animal models in which experimental insulin resistance was induced by intraportal administration of non-selective and selective neuronal nitric oxide synthase inhibitors, N-methyl-L-arginine (L-NMMA) or 7-nitroindazole. In these models, loss of hepatic nitric oxide productions is presumed to hinder a very potent insulin sensitizing mechanism referred to as meal induced sensitization that is anatomically linked to the nitrergic fibers of the anterior hepatic plexus. Cause and effect relationship between ADMA and insulin resistance has been proposed previously by others however the nature of this relationship has not been elucidated in detail. In our hypothesis, we suggest that ADMA by inhibiting both the neuronal and the endothelial forms of NOS, results both in insulin resistance and in accelerated atherosclerosis, therefore ADMA is the molecule responsible for the coexistence of these two conditions. We also suggest animal models and human studies to test our hypothesis, the results of which may offer novel approaches in the prevention of insulin resistance and atherosclerosis.

Arterial wall thickness is associated with insulin resistance in type 2 diabetic patients

The aim of the present study was to investigate the independent association of the intimal-medial thickness of carotid and femoral arteries (CA-IMT and FA-IMT), a marker of atheroscelosis, with insulin resistance in type 2 diabetic patients. We evaluated CA-IMT and FA-IMT by high-resolution ultrasonography and insulin resistance determined by euglycemic hyperinsulinemic clamp in 119 type 2 diabetic subjects, 71 males and 48 females (age, 54 +/- 12 (SD) years). In simple regression analyses, CA-IMT and FA-IMT were significantly inversely correlated with insulin sensitivity index (CA-IMT, r = -0.225, p = 0.010; FA-IMT, r = -0.186, p = 0.043, respectively). Multiple regression analysis was performed with the logarithm of CA-IMT or FA-IMT as a dependent variable and insulin sensitivity index as an independent variable along with known clinical risk factors. Insulin sensitivity index exhibited a significant independent contribution to log (CA-IMT) (beta = -0.204, p = 0.033) and to log (FA-IMT) (beta = -0.237, p = 0.010) in these models (CA-IMT, R(2) = 0.347, p < 0.0001; FA-IMT, R(2) = 0.398, p < 0.0001, respectively). In conclusion, insulin resistance is associated with both CA-IMT and FA-IMT in type 2 diabetic patients, suggesting that it is an independent risk factor for the development of atherosclerosis in type 2 diabetes.

Insulin resistant young subjects at risk of accelerated atherosclerosis exhibit a marked reduction in peripheral endothelial function early in life but not differences in intima-media thickness

Reduced bio-availability of nitric oxide leading to disturbed flow mediated (endothelial dependent) vasodilation (FMD) has been shown to be an early functional abnormality of the vascular system in insulin resistant individuals and other subjects at high risk for accelerated atherosclerosis. In addition, an increase of the intima-media thickness (IMT) is regarded as an early marker of morphological alterations of the vessel wall. Whether endothelial dysfunction (ED) is evident already at an early stage when morphological changes of the vessel wall are not apparent is still an open question. We, therefore, examined IMT and peripheral endothelial function in a group of young insulin resistant subjects in a cross-sectional study and compared these results with a metabolically healthy (insulin sensitive) control group. We measured IMT (distal common carotid arteries), endothelium-dependent and endothelium-independent vasodilation (flow mediated and glyceroltrinitrate induced vasodilation of the brachial artery) non-invasively with high resolution ultrasound (13 MHz) in 91 young normoglycemic subjects (40/51 M/F, median: 31 years, range 18-50 years). Insulin sensitivity was measured with a euglycemic, hyperinsulinemic glucose clamp. Despite a marked reduction in flow-mediated vasodilation in insulin resistant (IR) subjects (FMD: median 3.4%, range -4.0 to 12.5 in IR versus 6.6%, range -1.2 to 20.1% in insulin sensitive subjects; P = 0.017), there was no difference in endothelial independent vasodilation (16.3%, range 5.7-41.0% versus 16.1%, range 0.5-39.2%) and in IMT (0.50 mm, range 0.39-0.66 and 0.51, 0.40-0.70 mm, respectively). These data suggest that ED can be detected very early in the life of insulin resistant subjects whereas no significant structural changes, indicated by a thickening of the intima-media layer, could be found. We therefore conclude that for identification of subjects with a high risk for accelerated atherosclerosis at an early stage, measurement of flow mediated vasodilation of the brachial artery may be more helpful than measuring thickness of the vascular wall.

Plasma ghrelin, body fat, insulin resistance, and smoking in clinically healthy men: the atherosclerosis and insulin resistance study

The purpose of the study was to examine whether insulin sensitivity was associated with fasting plasma ghrelin concentrations in a population-based sample of 58-year-old clinically healthy Caucasian men. The methods used were dual-energy x-ray absorptiometry (DXA) for measurement of body composition and a conventional euglycemic hyperinsulinemic clamp, measuring glucose infusion rate (GIR) that was adjusted for fat-free mass. Plasma ghrelin was measured by radioimmunoassay. The results showed that ghrelin was not associated with GIR adjusted for fat-free mass or with GIR adjusted for body mass, and body fat, or waist circumference. Plasma ghrelin correlated negatively to body fat (-0.46, P<.001) and waist circumference (-0.45, P<.001). Ghrelin was also inversely related to systolic and diastolic blood pressure (r=-.29 and r=-0.34, respectively, P<.01) and positively to high-density lipoprotein (HDL) cholesterol (0.33, P<.01), and low-density lipoprotein (LDL) particle size (0.34, P<.001), but these associations did not remain after adjustment for body fat. Plasma ghrelin was associated with current smoking independent of waist circumference. Among current smokers, circulating plasma concentrations were higher in those who had smoked during the hour preceding the blood sample than those who had smoked 2 to 12 hours ago (P=.043). The conclusion is that whole body insulin sensitivity was not associated with plasma ghrelin concentrations. Body fatness was the strongest determinant of circulating ghrelin. It was found that acute smoking may affect ghrelin levels.

Early vascular damage in primary hypoalphalipoproteinemia

The relationship between hypoalphalipoproteinemia (hypoalpha), a metabolic disorder characterized by reduced high-density lipoprotein (HDL) cholesterol levels, and atherosclerotic disease is not completely understood. We investigated arterial functional and structural changes in 19 subjects with hypoalpha (HDL cholesterol < or = 0.7 mmol/L for men and < or = 0.8 mmol/L for women; 13 men; 47 +/- 7 years) and in 21 healthy control subjects (11 men; 46 +/- 13 years). Brachial-artery flow-mediated vasodilation (FMV) and intima-media thickness (IMT) of the carotid and femoral arteries were determined in all subjects. FMV was significantly lower in hypoalpha than in controls (5.6% +/- 4.3% v 8.2% +/- 2.7%; P <.05). IMT was greater in hypoalpha than in controls at both the internal carotid (0.83 +/- 0.1 mm v 0.69 +/- 0.1 mm) and superficial femoral level (0.83 +/- 0.2 mm v 0.68 +/- 0.1 mm; both P <.05). FMV had a positive correlation with HDL cholesterol (r =.42, P =.06) and a negative one with triglycerides (r = -0.38, P =.01). An inverse relationship was found between HDL cholesterol and internal carotid and superficial femoral IMT (r = -0.64 and r = -0.60, respectively; P <.01 for both) and a positive one between triglycerides and internal carotid and superficial femoral IMT (r =.53 and r =.47, P <.05). In a multivariate regression analysis, brachial FMV was predicted by HDL cholesterol and brachial diameter (beta =.42 and -0.43, respectively; both P <.05). HDL cholesterol was the only significant predictor of internal carotid and superficial femoral IMT (beta = -0.45 and -0.49, respectively; both P <.05). In conclusion, subjects with primary hypoalpha, without overt cardiovascular disease, are characterized by an impaired endothelial function and by an increase in large-artery IMT.

Postprandial lipemia in hypertension

OBJECTIVE

Many studies have shown that patients with coronary artery disease have an exaggerated rise and a delayed fall of plasma triglyceride (TG) concentration postprandially. We examined whether patients with essential hypertension have the same response to a fatty meal.

METHODS

A fatty meal (350g per 2 m(2) body surface with 83.5% fat) was given to 25 patients with essential hypertension (H) and to 25 normotensives (N). The two groups were matched for age, body mass index, lipid profile, basal glucose and insulin concentrations, and an index of homeostasis model of insulin resistance (HOMA-IR). A quantitative insulin sensitivity check index (QUICKI) was calculated. Blood samples were taken at 0, 4, 6, and 8 hours after the fatty meal. Lipid variables were measured in all samples. Blood glucose and insulin levels were measured in the fasting state.

RESULTS

Total and high density lipoprotein cholesterol, apolipoprotein A1 and B, lipoprotein (a), HOMA-IR and QUICKI did not differ significantly over time between the groups. The plasma TG concentration (mg/dL) increased significantly after fat loading in H (from 118 +/- 31 to 284 +/- 137 at 4 hours, 327 +/- 93 at 6 hours and 285 +/- 71 at 8 hours) compared to N group (from 105 +/- 29 to 150 +/- 38 at 4 hours, 148 +/- 40 at 6 hours and 115 +/- 34 at 8 hours), p = 0.001, p < 0.001 and p < 0.001, respectively.

CONCLUSION

This study suggests that patients with hypertension have an exaggerated response and delayed clearance of plasma TG concentration after fat loading.

The relationship between dysglycemia and atherosclerosis in South Asian, Chinese, and European individuals in Canada: a randomly sampled cross-sectional study

OBJECTIVE

Raised glucose levels extending from normal into the diabetic range (dysglycemia) are an emerging risk factor for clinical cardiovascular events. The relationship between dysglycemia and atherosclerosis (AS) in the general population and in different ethnic groups remains controversial.

RESEARCH DESIGN AND METHODS

Glucose tolerance, HbA1c, other metabolic risk factors for AS, and carotid mean maximal intimal media thickness were assessed in a random sample of 979 Canadians of South Asian, Chinese, and European descent.

RESULTS

The age and sex-adjusted intimal medial thickness increased 0.026 mm for every 0.9% increase in HbA1c in all participants (P < 0.0001) and in those of South Asian (P = 0.018), Chinese (P = 0.002), and European (P < 0.0001) descent. This progressive curvilinear relationship was most apparent at HbA1c levels >5.7%. The HbA1c-AS relationship persisted after adjustment for ethnicity, age, sex, diabetes status, abdominal obesity, insulin resistance, insulin secretion, fasting free fatty acids, blood pressure, and/or dyslipidemia (P < 0.004). Both diabetes (P = 0.002) and HbA1c (P < 0.0001) were determinants of the intimal medial thickness when included in separate statistical models. When included together in a single model, HbA1c (P < 0.0001) but not diabetes (P = 0.6) was a significant determinant.

CONCLUSIONS

The degree of AS is related to the level of HbA1c irrespective of diabetes status and independent of abdominal obesity and other markers of the metabolic syndrome. This progressive relationship between HbA1c and AS was observed within different ethnic groups.

A low high density lipoprotein (HDL) level is associated with carotid artery intima-media thickness in asymptomatic members of low HDL families

Low serum high-density lipoprotein cholesterol (HDL-C) is a strong predictor of coronary heart disease (CHD). The aim of the present study was to evaluate the metabolic parameters predicting the atherosclerotic changes in asymptomatic members of low HDL-C families. We performed carotid B-mode ultrasonography with intima-media thickness (IMT) measurement for 89 asymptomatic members of Finnish low HDL-C families. The family members were categorized as affected or unaffected according to the 10th age-gender specific HDL-C percentile. In the affected group, the most marked decrease of HDL subclasses was observed for HDL2-C when compared with the unaffected (109% difference). In the partial correlation analyses, age and gender showed significant correlations with the mean IMT (for age, r=0.880, P<0.001, and for gender, r=-0.361, P=0.018). Importantly, HDL-C and HDL2-C were significantly inversely related to the mean carotid IMT, also after correction for age (for HDL-C, r=-0.186, P=0.043, for HDL2-C, r=-0.208, P=0.029, when adjusted for age). The correlation for HDL-C was significant also when adjusted for gender. In conclusion, low HDL-C is associated with increased carotid artery IMT in asymptomatic members of low HDL-C families.

Endothelium-dependent flow-mediated vasodilatation, insulin resistance and the metabolic syndrome in 60-year-old men

OBJECTIVES

To evaluate the endothelium-dependent flow-mediated vasodilatation (FMD) in the brachial artery and to study the relationship to insulin sensitivity and to the metabolic syndrome in 60-year-old clinically healthy men.

SUBJECTS

The men were randomly selected from the general population (n = 55). The subjects with the metabolic syndrome were defined according to a definition proposed by a working group associated with the World Health Organization (WHO).

METHODS

Ultrasound images for measurement of lumen diameter of the brachial artery were recorded before and after reactive hyperaemia induced by occlusion of the artery, both with and without ischaemic hand exercise during the occlusion. Insulin-mediated glucose uptake was determined by euglycaemic hyperinsulinaemic clamp as a measure of insulin sensitivity.

RESULTS

The FMD was in the total group 3.2% when hyperaemia was induced by occlusion only and 8.7% after occlusion plus ischaemic hand exercise (P < 0.001, n = 51). However, no relationship was observed between any measure of FMD and insulin-mediated glucose uptake (r = -0.05 and r = 0.06, n = 47, P > 0.30). Furthermore, subjects with the metabolic syndrome (n = 13) did not differ in any measure of FMD compared with those with no risk factors (n = 11).

CONCLUSION

In this study the ultrasound method to evaluate endothelial function did not show that low insulin sensitivity or the metabolic syndrome were associated with impaired FMD in otherwise clinically healthy 60-year-old men.

Insulin resistance in non-diabetic subjects is associated with increased incidence of myocardial infarction and death

AIMS

To compare the incidence of myocardial infarction and death in non-diabetic subjects with and without insulin resistance.

METHODS

Population-based prospective cohort study, in Malmö, Sweden, of 4748 non-diabetic subjects (60% women), aged 46-68 years, with no history of myocardial infarction or stroke. The prevalence of insulin resistance was established by the homeostasis model assessment (HOMA) and defined as values above the sex-specific 75th percentile (1.80 for women and 2.12 for men). Incidence of myocardial infarction and death is based on record linkage with local and national registers. Cox's proportional hazards model was used to assess the influence of insulin resistance after adjustment for age, sex, hyperglycaemia, raised arterial blood pressure, dyslipidaemia, central obesity, smoking and leisure-time physical activity.

RESULTS

Sixty-two subjects suffered a coronary event, and 93 subjects died during the 6-year follow-up period. Insulin resistance was after adjustment for other factors included in the insulin resistance syndrome and other potential confounders, associated with an increased incidence of coronary events (relative risk (RR) 2.18; 95% confidence interval (CI) 1.22-3.87; P = 0.008) and deaths (RR 1.62; 1.03-2.55; P = 0.038).

CONCLUSIONS

Insulin resistance, as assessed by the HOMA method, was in this cohort of middle-aged non-diabetic subjects associated with an increased incidence of myocardial infarction and death. This risk remained when smoking, low physical activity and factors included in the insulin resistance syndrome were taken into account in a stepwise regression model.

Increased carotid artery intima-media thickness in subjects with primary hypoalphalipoproteinemia

The plasma concentration of high-density lipoprotein cholesterol (HDL-C) is inversely correlated with the incidence of atherosclerotic vascular events. In the present study, we evaluated pre-intrusive atherosclerosis in subjects with plasma HDL-C at the extremities of normal distribution. Fifty-five subjects with primary hypoalphalipoproteinemia (HypoALP) or hyperalphalipoproteinemia (HyperALP) were compared with fifty-five control subjects with average HDL-C levels, matched for sex, age, and plasma cholesterol. The average and maximal intima-media thicknesses (Avg-IMT and Max-IMT) of 48 carotid segments for each subject were approximately 40% greater in HypoALP than in control subjects (0.94 +/- 0.06 versus 0.69 +/- 0.04 mm, P=0.004, and 1.86 +/- 0.16 versus 1.35 +/- 0.10 mm, P=0.025, respectively). The IMT values in HyperALP subjects (Avg-IMT, 0.71 +/- 0.04 and Max-IMT, 1.38 +/- 0.14 mm) were the same as in controls. In a large cohort of hyperlipidemic subjects (n=559), significantly greater Avg-IMT and Max-IMT were found in subjects belonging to the first HDL-C quintile (<42 mg/dL) than in all the others. The measurement of carotid IMT in cases with HypoALP and HyperALP, and in a large series of hyperlipidemic patients, thus indicates that a low HDL-C is associated with significant pre-intrusive atherosclerosis, whereas a HDL-C level above average values does not lead to a further reduction of arterial wall thickening.

Postprandial elevation of remnant lipoprotein leads to endothelial dysfunction

Recent studies have demonstrated that elevated levels of cholesterol in the form of remnant-like particles (RLP-C) induce deterioration of endothelial function during the fasting state, but it is not known whether postprandial RLP-C elevation has the same effect. The objective of this study was to assess the effect of postprandial RLP-C elevation on endothelial function in 24 fasting normolipidemic subjects. Flow-mediated dilatation (FMD) during reactive hyperemia in the brachial artery was investigated. Serum lipids and lipoproteins during fasting and 4h after regular fat-loading were measured. Subjects were divided into 2 groups: the high responders (postprandial RLP-C level >7.5mg/dl, n=8) and the normal responders (postprandial RLP-C level < or =7.5mg/dl, n=16). Significant increases in the level of both triglycerides and RLP-C were observed in the high responders. Basal FMD in the high responders (4.3+/-3.0%) was significantly lower than that in the normal responders (8.3+/-2.4%) (p<0.01), but FMD after the fat-loading in both groups did not change significantly. The change in RLP-C levels during the fat-loading test correlated significantly with basal FMD (r=-0.588, p<0.01). Multiple regression analysis showed a significant correlation between basal FMD and the change in RLP-C levels (r=-0.488, p<0.02). The results of this study suggest that postprandial RLP-C elevation could be associated with atherosclerotic progression even in normolipidemic subjects.