Body mass index, lipid metabolism and estrogens: their impact on coronary heart disease.

Estrogens influence lipid metabolism and body fat distribution in women. Premenopausal women have increased lipoprotein lipase action in abdominal and femoral subcutaneous fat compared with men of the same age. Estrogens may also affect adipose tissue either directly through specific estrogen receptors or indirectly via their effects on other tissues. As adipose tissue produces several cytokines including leptin, adiponectin and interleukin-6, estrogens may alter their levels, thus influencing various biological processes. Lack of estrogens such as in menopause, causes an increase in visceral adiposity, leading to changes in lipid and lipoprotein metabolism. Due to those alterations, postmenopausal women are more prone to coronary heart disease. In this review the influence of estrogens on body mass index, lipid metabolism and some of the therapeutic options will be analyzed.

Cholesterol ester transfer protein (CETP), postprandial lipemia and hypolipidemic drugs.

Cholesterol ester transfer protein (CETP) plays a significant role in high density lipoprotein (HDL) metabolism and reverse cholesterol transport (RCT). A reduction in CETP activity leads to an increase in HDL-cholesterol levels. However, the relationship between reduced CETP function and atherosclerosis is complex and confusing. In the hypertriglyceridemic state, CETP is highly expressed and RCT leads to the formation of small dense low density lipoprotein (LDL) and small dense HDL, both of which are involved in the progression of atherosclerosis. Significant associations of the B1B1 genotype with higher plasma CETP concentration and/or CETP activity and lower HDL cholesterol were reported in several, but not all, studies. The magnitude of postprandial lipemia is also associated with plasma CETP concentration and lipoprotein content and size. Several conditions such as metabolic syndrome, hypertension, insulin resistance, obesity and familial hypercholesterolaemia are characterized by a more pronounced postprandial hypertriglyceridemia and delayed TG clearance than normal states. Thus, CETP is considered as a candidate target for drug therapy. A number of synthetic CETP inhibitors (CGS25159 and JTT-705) were evaluated in animals with satisfactory results. In humans, two CETP inhibitors were evaluated, JTT-705 and torcetrapib, leading to HDL increase. However, torcetrapib administration was associated with an increase in blood pressure and other "off-target" effects. It is also not clear whether the HDL produced during treatment with torcetrapib is bioactive (i.e. an "on target" undesirable action). In the current review, CETP function regarding lipid metabolism (in fasting and fed states) from human and animal studies as well as the current knowledge on CETP inhibitors are discussed. We also discuss gender influence on the action of hypolipidemic drugs and their effect on CETP mass and activity, as well as on the lipid profile.

Tangier disease four decades of research: a reflection of the importance of HDL.

Reduced circulating levels of high density lipoprotein cholesterol (HDL-C) are a frequent lipoprotein disorder in coronary heart disease patients and can be caused by either genetic and/or environmental factors (sedentary lifestyle, diabetes mellitus, smoking, obesity or a diet enriched in carbohydrates). Extremely low serum HDL-C levels occur in patients with Tangier disease (TD), which is caused by mutations in the adenosine triphosphate (ATP)-binding cassette transporter A1 (ABCA1). Clinical manifestations are related to the storage of cholesteryl esters in reticuloendothelial tissues and to peripheral neuropathy. This review focuses on the genetic and lipid abnormalities of TD, the consequence of these on clinical outcome and the possible treatment options. These abnormalities reflect the importance of HDL in the pathogenesis of vascular disease.

Pathophysiology of dyslipidaemia in the metabolic syndrome.

The insulin resistance/metabolic syndrome is characterised by the variable coexistence of hyperinsulinaemia, obesity, dyslipidaemia, and hypertension. The pathogenesis of the syndrome has multiple origins, but obesity and sedentary lifestyle coupled with diet and still largely unknown genetic factors clearly interact to produce the syndrome. Dyslipidaemia, the hallmark of the metabolic syndrome, includes increased flux of free fatty acids, raised triglycerides, apolipoprotein B, and small dense low density lipoprotein, and decreased high density lipoprotein cholesterol. The widely prevalent nature of the metabolic syndrome emphasises the importance of its diagnosis and treatment. This review analyses the clinical and dynamic features of this syndrome in the aspect of dyslipidaemia and its management.

Heterozygote men with familial hypercholesterolaemia may have an abnormal triglyceride response post-prandially. Evidence for another predictor of vascular risk in familial hypercholesterolaemia.

Familial hypercholesterolaemia (FH) is associated with premature coronary heart disease (CHD). Post-prandial hypertriglyceridaemia has also been associated with cardiovascular disease. Thus, an abnormal post-prandial triglyceride (TG) clearance may contribute to the heterogeneity in the risk of CHD in heterozygous (h) FH. Therefore, we investigated the response of TG levels to a fatty meal in men with hFH. We studied 26 Greek men divided into two groups: the hFH group of 14 men, mean age 39 (SD = 11) years and the control group of 12 healthy men, mean age 43 (50:5) years. An increased TG response to the fatty meal was defined as a post-prandial TG concentration (at 4, 6 or 8 h) greater than the highest TG concentration in any hour in any control individual. All hFH patients had normal baseline fasting TG levels. However, seven hFH men showed an abnormal TG response after the fatty meal; these patients had higher baseline fasting TG levels than others [1.5 (0.2) vs. 1.0 (0.4) mmol/l, p = 0.005]. The hFH men constituted a heterogeneous group regarding their TG response to the fatty meal compared with healthy men because 50% with higher, but nevertheless 'normal' basal TG levels, had an abnormal post-prandial TG response. The reduced activity of low-density lipoprotein receptors in hFH together with other defects in TG handling may explain the abnormal rise of TG levels post-prandially.

The effect of nicotinic acid and alcohol co-administration in Wistar rats.

The effects of co-administration of nicotinic acid (NA) and alcohol (Alc) on liver function in male Wistar rats were evaluated. The rats were randomized into five groups: (i) Olive oil (Oil), (ii) Alc+Oil, (iii) NA+Oil, (iv) NA+Alc+Oil, and (v) Controls (fed only normal rat chow). Alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AP), total cholesterol and triglycerides (TG) were measured. Liver histopathology was also assessed. The Alc+Oil group had higher TG levels compared with the NA+Alc+Oil group and all other groups, as well. NA+Oil group had higher levels of AP compared with Alc+Oil and Oil groups. The NA+Oil group had higher ALT levels compared with the Oil group. The Oil group had lower ALT levels compared with the control group. The Alc+Oil group had higher AST levels compared with the NA+Alc+Oil group, as well as with all other groups. Liver histopathology was within the normal range. A moderate amount of Alc daily together with NA is safe in rats. The NA and Alc co-administration reduces the TG and AST levels in rats, compared with the administration of Alc alone.

Differential response of high-density lipoproteins to first-step lipid-lowering diet according to their initial level.

BACKGROUND: A lipid-lowering diet has been shown to lower total cholesterol but also high-density-lipoprotein (HDL) cholesterol. The effect of the first-step lipid-lowering diet (as suggested by the European Atherosclerosis Society) on HDL levels was studied in 129 Greek patients aged 52.7 +/- 9.8 years, of whom 78 were men and 51 women of similar ages. METHODS: Total, HDL, and low-density-lipoprotein (LDL) cholesterol, and the total: HDL cholesterol and triglyceride ratio were assessed before and 3 months after the diet. RESULTS: Overall, total cholesterol decreased by 12% (P < 0.001), LDL by 15% (P < 0.001), HDL by 3% (NS), triglycerides by 12% (P < 0.01), and total: HDL cholesterol ratio by 11% (P < 0.001). A difference was found in the response to diet according to baseline HDL levels: in patients with HDL of 39 mg/dl or higher (group A), HDL decreased by 10% and the total: HDL cholesterol ratio by 3%, whereas in those with HDL lower than 39 mg/dl (group B) HDL increased by 17% and the total: HDL cholesterol ratio decreased by 22%. The difference between the groups was statistically significant (P < 0.001) for these two values as well as for triglycerides, but not for total cholesterol and LDL. No difference in the responses between men and women was found. CONCLUSION: This differential response to diet should be taken into account when planning treatment. Patients with baseline HDL levels higher than 39 mg/dl should probably be considered for early treatment not only by diet but by lipid-lowering-HDL-raising drugs as well.