Reduced HDL particle size as an additional feature of the atherogenic dyslipidemia of abdominal obesity.

Reduced plasma HDL cholesterol concentration has been associated with an increased risk of coronary heart disease. However, a low HDL cholesterol concentration is usually not observed as an isolated disorder because this condition is often accompanied by additional metabolic alterations. The objective of this study was to document the relevance of assessing HDL particle size as another feature of the atherogenic dyslipidemia found among subjects with visceral obesity and insulin resistance.

Race differences in the response of postheparin plasma lipoprotein lipase and hepatic lipase activities to endurance exercise training in men: results from the HERITAGE Family Study.

Endurance exercise training is known to produce favorable changes in the metabolic profile including reduced plasma triglyceride (TG) and increased high-density lipoprotein (HDL) cholesterol concentrations. These metabolic improvements are likely to contribute to the reduced coronary heart disease (CHD) risk often observed in physically active individuals. However, the physiological mechanisms responsible for such improvements in TG and HDL cholesterol concentrations with endurance exercise are not fully understood.

Health consequences of visceral obesity.

Visceral obesity is associated with metabolic abnormalities that increase the risk of type 2 diabetes and coronary heart disease. Obese patients with a substantial accumulation of visceral adipose tissue are characterized by higher insulinaemic and glycaemic responses during an oral glucose challenge as well as by a deteriorated plasma lipoprotein-lipid profile compared with individuals with normal body weights or obese subjects with low levels of visceral adipose tissue. Results of the Quebec Cardiovascular Study have shown that the cluster of metabolic disturbances observed among subjects with visceral obesity (hyperinsulinaemia, hyperapolipoprotein B and small, dense low-density lipoprotein (LDL) particles) is associated with a 20-fold increase in the risk of coronary heart disease in a sample of middle-aged men followed over 5 years.

Age and duration of follow-up as modulators of the risk for ischemic heart disease associated with high plasma C-reactive protein levels in men.

Background: Plasma C-reactive protein (CRP) levels recently have been identified as an emerging risk factor for ischemic heart disease (IHD). However, whether plasma CRP levels predict an increased risk for future IHD beyond traditional risk factors has yet to be evaluated in a large prospective, population-based study.

Methods: The association between elevated plasma CRP levels and the risk for future IHD was investigated in the prospective, population-based cohort of 2037 IHD-free middle-aged men from the Quebec Cardiovascular Study.

Effects of the FABP2 A54T mutation on triglyceride metabolism of viscerally obese men.

Objective: Viscerally obese individuals are frequently characterized by a proatherogenic condition. A missense mutation (A54T) in the fatty acid binding protein type 2 (FABP2) gene has been associated with insulin resistance and obesity. This study examined the effect of this mutation on lipoprotein levels in viscerally obese hyperinsulinemic condition.

Comparison of various electrophoretic characteristics of LDL particles and their relationship to the risk of ischemic heart disease.

Background: Several cross-sectional studies and 3 prospective, nested, case-control studies have indicated that individuals with small, dense low density lipoprotein (LDL) particles are at increased risk for ischemic heart disease (IHD). However, whether LDL particle size is an independent risk factor for future IHD events remains controversial. The objective of the present study was to further analyze the cardiovascular risk associated with various electrophoretic characteristics of LDL particles in men.

Interactions among the glucocorticoid receptor, lipoprotein lipase and adrenergic receptor genes and abdominal fat in the Québec Family Study.

Objective: To investigate whether interactions between glucocorticoid receptor (GRL), lipoprotein lipase (LPL) and adrenergic receptor (ADR) gene markers contribute to individual differences in indicators of adiposity and abdominal obesity, including visceral fat level.

Design And Subjects: Cross-sectional study; 742 individuals from the phase 2 of the Québec Family Study cohort.

Measurements: Total body fat assessed by hydrodensitometry and the sum of six skinfolds.

Exercise in weight management of obesity.

Obesity is a chronic metabolic disorder associated with CVD and increased morbidity and mortality. When the BMI is > or = 30 kg/m2, mortality rates from all causes, and especially CVD, are increased by 50% to 100%. There is strong evidence that weight loss in overweight and obese individuals improves risk factors for diabetes and CVD.

Difference in leptin response to a high-fat meal between lean and obese men.

The aim of this study was to compare the leptin responses to a high-fat meal in lean and obese men, and to investigate whether the net leptin response (area under the incremental curve) after the meal was related to the thermic effect of food (TEF). Blood samples were collected after an overnight fast and every 2 h for 8 h after a high-fat breakfast (60 g of fat/m(2) body surface area) in 12 lean and 12 obese men for determination of glucose, insulin and leptin. The TEF was calculated as postprandial energy expenditure minus fasting energy expenditure, as measured by indirect calorimetry.

Is the relationship between adipose tissue and waist girth altered by weight loss in obese men?

Objective: The aim of the present study was to examine whether the association of waist girth to visceral adipose tissue (AT) accumulation was altered by weight loss in abdominally obese men.

Research Methods And Procedures: We studied 45 dyslipidemic abdominally obese men (45.4 +/- 6.

Comparison of two techniques for measurement of visceral adipose tissue cross-sectional areas by computed tomography.

Most computed tomography (CT) scanners used today are able to accurately measure adipose tissue (AT) areas at any site of the body. However, first generation CT scanners used by some medical centers are not equipped with appropriate software allowing the measurements of AT areas. The aim of this study was to validate a technique of AT area measurements independent from CT scanner software.

Waist and hip circumferences have independent and opposite effects on cardiovascular disease risk factors: the Quebec Family Study.

Background: A high waist-to-hip ratio is associated with unfavorable cardiovascular disease risk factors. This could be due to either a relatively large waist or a small hip girth.

Objective: We sought to define the separate contributions of waist girth, hip girth, and body mass index (BMI) to measures of body composition, fat distribution, and cardiovascular disease risk factors.

A prospective, population-based study of low density lipoprotein particle size as a risk factor for ischemic heart disease in men.

Background: The current interpretation of the increased risk of ischemic heart disease (IHD) associated with reduced low density lipoprotein (LDL) particle size is based entirely on data derived from relatively small case-control studies, with a lack of evidence from large, prospective, population-based cohort data.

Objectives: To investigate the association between LDL particle size and incident IHD on the basis of data from the entire population-based, prospective cohort of men from the Quebec Cardiovascular Study.

Patients And Methods: Analyses were conducted in a cohort of 2057 men who were all initially free of IHD, and who were followed up over a five-year period, during which 108 first IHD events (myocardial infarction, angina or coronary death) were recorded.

Genetic variation at the lipoprotein lipase locus and plasma lipoprotein and insulin levels in the Québec Family Study.

The associations between the S447X, BamHI, HindIII and PvuII DNA variants of the lipoprotein lipase (LPL) gene and indicators of body fat, fat distribution and plasma lipids and insulin were studied in the Québec Family Study cohort. Strong linkage disequilibrium among all the markers was observed. For the S447X polymorphism, plasma very low density lipoprotein (VLDL)-cholesterol (chol) (P<0.

A new method for HDL particle sizing by polyacrylamide gradient gel electrophoresis using whole plasma.

Low plasma levels of HDL cholesterol have been associated with an increased risk of coronary heart disease. HDL particles are heterogeneous with respect to size and apolipoprotein content. The objective of the present study was to develop a method to generate lipid-stainable calibrators that would allow the assessment of HDL particle size from whole plasma, using polyacrylamide gradient gel electrophoresis (PAGGE).

Effect of a six month gemfibrozil treatment and dietary recommendations on the metabolic risk profile of visceral obese men.

Objective: The aim of the present study was to investigate the effects of a 6 month gemfibrozil treatment.

Subjects: A sample of 64 visceral obese men (age 46+/-6 y; body mass index 31+/-3 kg/m(2); waist circumference 104+/-7 cm; mean+/-s.d.

[Fat distribution and metabolism].

It is well known that adipose tissue distribution is an important factor involved in the etiology of type 2 diabetes and cardiovascular diseases. Adipose tissue distribution is obviously different between men and women, men being prone to accumulate their excess of energy in the abdominal region, more specifically in the intra-abdominal depot (visceral) whereas women show a selective deposition of adipose tissue in the gluteo-femoral region. Several studies have demonstrated an association between age and adipose tissue distribution and a selective deposition of visceral adipose tissue has been reported with age, in both men and women.

Effects of endurance exercise training on plasma HDL cholesterol levels depend on levels of triglycerides: evidence from men of the Health, Risk Factors, Exercise Training and Genetics (HERITAGE) Family Study.

High density lipoprotein (HDL) cholesterol concentrations have been shown to increase with regular endurance exercise and, therefore, can contribute to a lower risk of coronary heart disease in physically active individuals compared with sedentary subjects. Although low HDL cholesterol levels are frequently observed in combination with hypertriglyceridemia, some individuals may be characterized by isolated hypoalphalipoproteinemia, ie, low HDL cholesterol levels in the absence of elevated triglyceride (TG) concentrations. The present study compared the responses of numerous lipoprotein-lipid variables to a 20-week endurance exercise training program in men categorized on the basis of baseline TG and HDL cholesterol concentrations: (1) low TG and high HDL cholesterol (normolipidemia), (2) low TG and low HDL cholesterol (isolated low HDL cholesterol), (3) high TG and high HDL cholesterol (isolated high TGs), and (4) high TGs and low HDL cholesterol (high TG/low HDL cholesterol).

Evidence for the existence of adaptive thermogenesis during weight loss.

The present study was performed to further investigate the adaptive component of thermogenesis that appears during prolonged energy restriction. Fifteen obese men and twenty obese women underwent a 15-week weight-loss programme. During this programme, body weight and composition as well as resting energy expenditure (REE) were measured at baseline, after 2 and 8 weeks of energy restriction (-2929 kJ/d) and drug therapy (or placebo), and finally 2-4 weeks after the end of the 15-week drug therapy and energy restriction intervention, when subjects were weight stable.

Elevated C-reactive protein: another component of the atherothrombotic profile of abdominal obesity.

Recent studies have suggested that elevated plasma C-reactive protein (CRP) levels are associated with the features of insulin resistance syndrome. In the present study, we have examined the contribution of body composition measured by hydrostatic weighing and of abdominal adipose tissue (AT) accumulation assessed by computed tomography to the variation in plasma CRP levels associated with atherogenic dyslipidemia of the insulin resistance syndrome in a sample of 159 men, aged 22 to 63 years, covering a wide range of adiposity (body mass index values from 21 to 41 kg/m(2)). Plasma CRP levels showed positive and significant correlations with body fat mass (r=0.

Deterioration of the metabolic risk profile in women. Respective contributions of impaired glucose tolerance and visceral fat accumulation.

Objective: To determine whether the impaired glucose tolerance (IGT) state contributes to the deterioration of the metabolic profile in women after taking into account the contribution of visceral adipose tissue (AT) accumulation, as measured by computed tomography.

Research Design And Methods: We studied 203 women with normal glucose tolerance (NGT) and 46 women with IGT, defined as a glycemia between 7.8 and 11.

Impact of high-intensity exercise on energy expenditure, lipid oxidation and body fatness.

Objective: Two studies were conducted to assess the potential of an increase in exercise intensity to alter energy and lipid metabolism and body fatness under conditions mimicking real life.

Methods: Study 1 was based on the comparison of adiposity markers obtained in 352 male healthy adults who participated in the Québec Family Study who either regularly participated in high-intensity physical activities or did not. Study 2 was designed to determine the effects of high-intensity exercise on post-exercise post-prandial energy and lipid metabolism as well as the contribution of beta-adrenergic stimulation to such differences under a real-life setting.