Importance and Management of Dyslipidemia in the Metabolic Syndrome

A combined continuous and interval aerobic training improves metabolic syndrome risk factors in men

Individuals with metabolic syndrome have significantly higher risk of cardiovascular disease and type 2 diabetes leading to premature death mortality. Metabolic syndrome has a complex etiology; thus, it may require a combined and multi-targeted aerobic exercise regimen to improve risk factors associated with it. Therefore, the aim of this study was to evaluate the effect of combined continuous and interval aerobic training on patients with metabolic syndrome. Thirty adult male with metabolic syndrome (54±8 years) were randomly divided into two groups: test training group (TTG; n=15) and control group (CG; n=15). Subjects in TTG performed combined continuous and interval aerobic training using a motorized treadmill three times per week for 16 weeks. Subjects in CG were advised to continue with their normal activities of life. Twenty-two men completed the study (eleven men in each group). At the end of the study, in TTG, there were significant (for all, P<0.05) reductions in total body weight (−3.2%), waist circumference (−3.43 cm), blood pressure (up to −12.7 mmHg), and plasma insulin, glucose, and triacylglyceride levels. Moreover, there were significant (for all, P<0.05) increases VO₂max (−15.3%) and isometric strength of thigh muscle (28.1%) and high-density lipoprotein in TTG. None of the above indices were changed in CG at the end of 16-week study period. Our study suggests that adoption of a 16-week combined continuous and interval aerobic training regimen in men with metabolic syndrome could significantly reduce cardiovascular risk factors in these patients.

The relationship between obesity and coronary artery disease

Obesity continues to be a growing issue in the United States, with an estimated prevalence of 72 million people. There are major health implications associated with obesity, including its relationship with hypertension, diabetes mellitus type 2, metabolic syndrome, and dyslipidemia, all independent risk factors for coronary artery disease (CAD). Despite the increased risk of developing CAD, in recent years an "obesity paradox" has been described in which moderately obese individuals with established cardiovascular disease, including CAD, appear to have mortality similar to their normal-weight counterparts. This review examines the relationship between obesity and CAD, including the increased risk of hypertension, diabetes mellitus, metabolic syndrome, and dyslipidemia, along with a discussion of the obesity paradox and the benefits of weight reduction.

Reevaluation of the prevalence of metabolic syndrome in an urban area of Turkey

OBJECTIVE

Our aim was to reveal a change in the prevalence of metabolic syndrome (MS) in the province of Konya in five years.

METHODS

We studied 202 obese children and adolescents (body mass index >95th percentile) aged between 7 and 18 years. The diagnosis of impaired glucose tolerance, type 2 diabetes mellitus (T2DM), and MS were defined according to the modified World Health Organization criteria adapted for children.

RESULTS

MS was found in 56.4 % with a significantly higher rate among adolescents aged 12-18 years (63.2%) than among prepubertal children aged 7-11 years (47%) (p=0.01). The prevalence figures for insulin resistance, glucose intolerance, and T2DM were 60, 8, and 2% among prepubertal children and 81.8, 12.8, and 0% among adolescents, respectively. The prevalence of fasting hyperinsulinemia in adolescents was significantly higher than in prepubertal children (p<0.001). Hypertension was significantly more common in adolescents (42.8%) than in prepubertal children (32.9%) (p=0.04).

CONCLUSIONS

We found that the incidence of MS in the city center of Konya approximately doubled in the last five years with increased rates of morbidity and abnormal lipid profiles.

Perturbation of lipids and glucose metabolism associated with previous 2,4-D exposure: a cross-sectional study of NHANES III data, 1988-1994

BACKGROUND

Results from previous population studies showed that mortality rates from acute myocardial infarction and type-2 diabetes during the 1980s and 1990s in rural, agricultural counties of Minnesota, Montana, North and South Dakota, were higher in counties with a higher level of spring wheat farming than in counties with lower levels of this crop. Spring wheat, one of the major field crops in these four states, was treated for 85% or more of its acreage with chlorophenoxy herbicides. In the current study NHANES III data were reviewed for associations of 2,4-dichlorophenoxy acetic acid (2,4-D) exposure, one of the most frequently used chlorophenoxy herbicides, with risk factors that are linked to the pathogenesis of acute myocardial infarction and type-2 diabetes, such as dyslipidemia and impaired glucose metabolism.

METHODS

To investigate the toxicity pattern of chlorophenoxy herbicides, effects of a previous 2,4-D exposure were assessed by comparing levels of lipids, glucose metabolism, and thyroid stimulating hormone in healthy adult NHANES III subjects with urinary 2,4-D above and below the level of detection, using linear regression analysis. The analyses were conducted for all available subjects and for two susceptible subpopulations characterized by high glycosylated hemoglobin (upper 50th percentile) and low thyroxine (lower 50th percentile).

RESULTS

Presence of urinary 2,4-D was associated with a decrease of HDL levels: 8.6% in the unadjusted data (p-value = 0.006), 4.8% in the adjusted data (p-value = 0.08), and 9% in the adjusted data for the susceptible subpopulation with low thyroxine (p-value = 0.02). An effect modification of the inverse triglycerides-HDL relation was observed in association with 2,4-D. Among subjects with low HDL, urinary 2,4-D was associated with increased levels of triglycerides, insulin, C-peptide, and thyroid stimulating hormone, especially in the susceptible subpopulations. In contrast, subjects with high HDL did not experience adverse 2,4-D associated effects.

CONCLUSIONS

The results indicate that exposure to 2,4-D was associated with changes in biomarkers that, based on the published literature, have been linked to risk factors for acute myocardial infarction and type-2 diabetes.

Bezafibrate induces myotoxicity in human rhabdomyosarcoma cells via peroxisome proliferator-activated receptor alpha signaling

Fibrates, the ligands of peroxisome proliferator-activated receptor alpha (PPARalpha), are used as a class of lipid-lowering drugs in clinical practice for the treatment of dyslipidemia. Fibrates are well tolerated in most cases concomitantly with occasional adverse reactions including muscular toxicity, which is enhanced by the combination with statins. This study was designed to investigate the effects of bezafibrate as a PPARalpha agonist on human embryo rhabdomyosarcoma (RD) cells and possible mechanisms responsible for bezafibrate-mediated myopathy. The results revealed that bezafibrate caused a dose-dependent decrease in cell viability, which was fortified in association with atorvastatin at a pharmacological dose. Bezafibrate at toxic doses of 300 and 1000microM upregulated PPARalpha at the mRNA level, counteracted by a PPARalpha antagonist (MK886). Bezafibrate at a toxic dose induced typical apoptotic characteristics related to the inhibition of phosphorylation of Akt which was blocked by PPARalpha antagonist. Toxic doses of bezafibrate initiated a significant increase in pyruvate dehydrogenase kinase 4 mRNA and protein levels, compromised by MK886. These results suggest the critical roles of PPARalpha signaling in bezafibrate-induced myotoxicity and the involvement of apoptosis through Akt pathway.

CPAP treatment in the coexistence of obstructive sleep apnea syndrome and metabolic syndrome, results of one year follow up

OBJECTIVE

To investigate the effect of one year continuous positive airway pressure (CPAP) treatment on metabolic syndrome (MS) prevalence and components in patients diagnosed with both obstructive sleep apnea syndrome (OSAS) and metabolic syndrome.

METHODS

This was a single center, observational prospective cohort study. 38 patients who were diagnosed with OSAS after polysomnographic analysis in sleep laboratory and diagnosed with MS according to National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) guideline and underwent CPAP treatment were followed for one year. After the 1 year of follow up period on CPAP treatment, the prevalence of MS was evaluated again.

RESULTS

20 (13 male, 7 female) of 38 patients completed the entire study. Mean age was 50+/-7.7.4 patients were under treatment for diabetes mellitus (DM), 9 for hypertension (HT). After one year of follow up on CPAP treatment, the prevalence of MS decreased by 45%. When each components of MS were evaluated, no significant difference was found in fasting blood glucose, triglyceride levels and systolic and diastolic blood pressure after treatment (p>0.05). However, significant difference was observed in waist circumference (p=0.002), HDL cholesterol (p=0.001) and BMI (p=0.01) after treatment.

DISCUSSION

If MS accompanies OSAS, which is a cardiovascular risk factor by itself, treatment indications of CPAP should be reevaluated. Thus, if OSA patients meet the criteria of MS even though they do not have obvious DM, HT and hyperlipidemia, initiating CPAP treatment at lower AHI levels may contribute to the prevention and development of cardiovascular disease.

Impact of obesity on the pathogenesis and prognosis of coronary heart disease

Obesity has a significant adverse effect on coronary heart disease (CHD) risk factors, including hypertension, dyslipidemia, and the metabolic syndrome/diabetes. Obesity is an independent risk factor for CHD events; however, obese patients with CHD generally have a more favorable prognosis, with the worst prognosis associated with either underweight or morbidly obese patients. In this manuscript, the authors review the impact of obesity on overall CHD risk as well as the prognosis of obese patients with established CHD.

Investigation and management of hypertriglyceridaemia

While the precise definition of hypertriglyceridaemia remains contentious, the condition is becoming more common in western populations as the prevalence of obesity and diabetes mellitus rise. Although there is strong epidemiological evidence that hypertriglyceridaemia is an independent risk factor for cardiovascular disease, it is has been difficult to demonstrate this by drug intervention studies, as drugs that reduce triglycerides also raise high density lipoprotein cholesterol. Precise target values have also been difficult to agree, although several of the new guidelines for coronary risk management now include triglycerides. The causes of hypertriglyceridaemia are numerous. The more severe forms have a genetic basis, and may lead to an increased risk of pancreatitis. Several types of hypertriglyceridaemia are familial and are associated with increased cardiovascular risk. Secondary causes of hypertriglyceridaemia are also numerous and it is important to exclude these before starting treatment with specific triglyceride-lowering agents. Lifestyle management is also very effective and includes weight reduction, restricted alcohol and fat intake and exercise.

Metformin increases HDL3-cholesterol and decreases subcutaneous truncal fat in nondiabetic patients with HIV-associated lipodystrophy

The purpose of this study was to assess metformin effects on high-density lipoprotein (HDL) composition of patients with HIV-associated lipodystrophy (LDHIV). Twenty-four adult outpatients were enrolled to receive metformin (1700 mg/d) during 6 months, but 2 were lost to follow-up and 6 stopped the drug due to adverse events (gastrointestinal in 5, and excessive weight loss in 1). From the 16 subjects who completed the study, 69% were female. At baseline, 3 and 6 months, we assessed: weight, waist and hip circumferences, blood pressure, fasting glucose and insulin, homeostasis model assessment of insulin resistance (HOMA2-IR), lipids, and HDL subfractions by microultracentrifugation. At 0 and 6 months, body fat distribution was assessed by computed tomography (CT) scan (L4 and middle femur). Metformin use was associated with reduction of mean weight (-2.4Kg at 6 months; p < 0.001), body mass index, waist, waist-to-hip ratio and a marked decrease in blood pressure (p < 0.001). Subcutaneous (p = 0.01) and total abdominal fat (p = 0.002) were reduced, but no change was found in visceral or thigh fat. No difference was detected on plasma glucose, insulin, HOMA2-IR, cholesterol or triglycerides, except for an increase in HDL3-cholesterol (from 21 mg/dL to 24 mg/dL, p = 0.002) and a reduction of nascent HDL (the fraction of plasma HDL-cholesterol not associated to subfractions HDL2 or HDL3) (p = 0.008). Adverse effects were very common, but most were gastrointestinal and mild. Thus, metformin use in LDHIV increases HDL3-cholesterol (probably due to improved maturation of HDL) and decreases blood pressure, weight, waist, and subcutaneous truncal fat, making this an attractive option for preventing cardiovascular disease in this population.

Zinc deficiency alters lipid metabolism in LDL receptor deficient mice treated with rosiglitazone

Zinc is a structural and functional component of PPAR and zinc deficiency may be associated with an increased risk for cardiovascular diseases. We tested the hypothesis that zinc deficiency compromises lipid metabolism in rosiglitazone (RSG)-treated mice lacking the LDL-receptor (LDL-R) gene. LDL-R-deficient mice were maintained for 3 wk on low-fat (7 g/100 g) diets that were either zinc deficient or zinc adequate. Subsequently, diets were adjusted to a high-fat (HF) (15 g/100 g) regimen for 1 wk to produce a biological environment of mild oxidative and inflammatory stress. One-half of the mice within each zinc group was gavaged daily with the PPARgamma agonist RSG starting 2 d prior to the HF feeding. Selected lipid parameters were studied. Zinc deficiency increased plasma total cholesterol, which was also elevated by RSG. Zinc deficiency also caused an increased lipoprotein-cholesterol distribution toward the non-HDL fraction (VLDL, intermediate density lipoprotein, LDL). Plasma total fatty acids tended to increase during zinc deficiency and RSG treatment resulted in similar changes in the fatty acid profile in zinc-deficient mice. Fatty acid translocase (FAT/CD36) expression in abdominal aorta was upregulated by RSG only in zinc-deficient mice. In contrast, RSG treatment markedly increased lipoprotein lipase (LPL) expression only in zinc-adequate mice. In vitro studies confirmed that adequate zinc is required for RSG-induced PPARgamma activity to transactivate target genes. These data suggest that in this atherogenic mouse model treated with RSG, lipid metabolism can be compromised during zinc deficiency and that adequate dietary zinc may be considered during therapy with the antidiabetic medicine RSG.

Rimonabant reduces obesity-associated hepatic steatosis and features of metabolic syndrome in obese Zucker fa/fa rats

This study investigated the effects of rimonabant (SR141716), an antagonist of the cannabinoid receptor type 1 (CB1), on obesity-associated hepatic steatosis and related features of metabolic syndrome: inflammation (elevated plasma levels of tumor necrosis factor alpha [TNFalpha]), dyslipidemia, and reduced plasma levels of adiponectin. We report that oral treatment of obese (fa/fa) rats with rimonabant (30 mg/kg) daily for 8 weeks abolished hepatic steatosis. This treatment reduced hepatomegaly, reduced elevation of plasma levels of enzyme markers of hepatic damage (alanine aminotransferase, gamma glutamyltransferase, and alkaline phosphatase) and decreased the high level of local hepatic TNFalpha currently associated with steatohepatitis. In parallel, treatment of obese (fa/fa) rats with rimonabant reduced the high plasma level of the proinflammatory cytokine TNFalpha and increased the reduced plasma level of the anti-inflammatory hormone adiponectin. Finally, rimonabant treatment also improved dyslipidemia by both decreasing plasma levels of triglycerides, free fatty acids, and total cholesterol and increasing the HDLc/LDLc ratio. All the effects of rimonabant found in this study were not or only slightly observed in pair-fed obese animals, highlighting the additional beneficial effects of treatment with rimonabant compared to diet. These results demonstrate that rimonabant plays a hepatoprotective role and suggest that this CB1 receptor antagonist potentially has clinical applications in the treatment of obesity-associated liver diseases and related features of metabolic syndrome.

Progeria of stem cells: stem cell exhaustion in Hutchinson-Gilford progeria syndrome

Hutchinson-Gilford progeria syndrome (HGPS) is a rare, fatal genetic disorder that is characterized by segmental accelerated aging. The major causal mutation associated with HGPS triggers abnormal messenger RNA splicing of the lamin A gene leading to changes in the nuclear architecture. To date, two models have been proposed to explain how mutations in the lamin A gene could lead to HGPS, structural fragility and altered gene expression. We favor a compatible model that links HGPS to stem cell-driven tissue regeneration. In this model, nuclear fragility of lamin A-deficient cells increases apoptotic cell death to levels that exhaust tissues' ability for stem cell-driven regeneration. Tissue-specific differences in cell death or regenerative potential, or both, result in the tissue-specific segmental aging pattern seen in HGPS. We propose that the pattern of aging-related conditions present or absent in HGPS can provide insight into the genetic and environmental factors that contribute to normal aging.

Le syndrome métabolique

Metabolic syndrome is public health problem. The characteristic feature is an association between factors contributing to increased cardiovascular risk. Several definitions have been proposed from 1998 to 2005. All proposed definitions take into consideration insulin resistance and its corollary hyperglycemia, overweight, hypertriglyceridemia, and LDL-cholesterol lowering. The most widely used definitions are proposed by the World Health Organization (WHO) and the American "Cholesterol" program (NCEP-ATpIII). The prevalence of metabolic syndrome varies by geographic region as a function of the chosen definition, the study methodology, the selection criteria, the age and gender of the study population, and the period of the study. Prevalence is higher in the United States than Europe and increases with age. A growing number of adolescents appear to meet the criteria of metabolic syndrome. Irrespective of the definition retained, metabolic syndrome is associated with increased cardiovascular risk and increased risk of type II diabetes. Sound evidence is however lacking on whether the risk is greater than that of taking into account each individual factor. Several points remain to be clarified concerning the underlying mechanisms. Visceral adipose tissue appears to be a key element in the process via anomalous function related to obesity and insulin resistance. Management is based mainly on reduction of body weight and regular physical activity. Drugs may be necessary to correct for the dyslipidemia, normalize blood glucose and reduce blood pressure.