Beta2-adrenergic activity modulates vascular tone regulation in lecithin:cholesterol acyltransferase knockout mice.

Lecithin:cholesterol acyltransferase (LCAT) deficiency is associated with hypoalphalipoproteinemia, generally a predisposing factor for premature coronary heart disease. The evidence of accelerated atherosclerosis in LCAT-deficient subjects is however controversial. In this study, the effect of LCAT deficiency on vascular tone and endothelial function was investigated in LCAT knockout mice, which reproduce the human lipoprotein phenotype. Aortas from wild-type (Lcat(wt)) and LCAT knockout (Lcat(KO)) mice exposed to noradrenaline showed reduced contractility in Lcat(KO) mice (P<0.005), whereas acetylcholine exposure showed a lower NO-dependent relaxation in Lcat(KO) mice (P<0.05). Quantitative PCR and Western blotting analyses suggested an adequate eNOS expression in Lcat(KO) mouse aortas. Real-time PCR analysis indicated increased expression of ß2-adrenergic receptors vs wild-type mice. Aorta stimulation with noradrenaline in the presence of propranolol, to abolish the ß-mediated relaxation, showed the same contractile response in the two mouse lines. Furthermore, propranolol pretreatment of mouse aortas exposed to L-NAME prevented the difference in responses between Lcat(wt) and Lcat(KO) mice. The results indicate that LCAT deficiency leads to increased ß2-adrenergic relaxation and to a consequently decreased NO-mediated vasodilation that can be reversed to guarantee a correct vascular tone. The present study suggests that LCAT deficiency is not associated with an impaired vascular reactivity.

High uptake of colonoscopy in first-degree relatives of patients with colorectal cancer in a healthcare region: a population-based, prospective study.

BACKGROUND AND STUDY AIMS: A screening program in first-degree relatives (FDRs) of colorectal cancer (CRC) patients (index patients) was started in Trentino, Italy, to analyze factors that influence uptake of CRC screening among invited FDRs (first objective) and to describe colorectal findings among those undergoing colonoscopy (secondary objective). PATIENTS AND METHODS: FDRs aged between 45 and 75 years were invited; exclusion criteria were: colonoscopy or barium enema in the preceding 5 years, a history of familial adenomatous polyposis, hereditary nonpolyposis colorectal cancer, inflammatory bowel diseases, and severe comorbidities. FDRs who were eligible but were not invited for screening because consent was not obtained from the index patients were considered as the control group. FDRs were invited by the education campaign targeted at the population at risk (both study and control groups); in the study group, interventions targeting individuals at risk (letters, phone calls, face-to-face counseling) were implemented. RESULTS: Starting from 626 new index cases of diagnosed CRC, 725 FDRs were invited to counseling; 77.6 % of these attended for colonoscopy in the study group vs. 8 % in the control group ( P < 0.0001). Predictors of colonoscopy uptake were FDR age above 60 years [odds ratio (OR) 2.50, 95 %CI 1.72 - 3.62], complex family history (simple family history: one CRC at age above 60 years; complex family history: one CRC at age below 60 or two or more CRC; OR 1.54; 95 %CI 1.04 - 2.33) and living in a rural area (OR 1.64, 95 %CI 1.12 - 2.44). Of the 560 FDRs in the study group, 186 (33.8 %) had adenomas, and 48 (8.8 %) had advanced adenomas or cancer. CONCLUSIONS: Interventions that target FDRs of patients with CRC, especially those younger than 60 years, with a complex family history of CRC and who live in a rural area, may improve uptake of CRC screening via colonoscopy.

Pharmacological control of hypertriglyceridemia.

Hypertriglyceridemia has been recently recognized as a vascular risk factor, based on both clinical and experimental findings. Epidemiological studies clearly showed that elevated plasma triglycerides in subjects with low high-density lipoprotein (HDL) cholesterol (<35 mg/dl) and/or a low-density lipoprotein (LDL)/HDL cholesterol ratio > 5 are associated with an elevated risk for coronary heart disease (CHD), while intervention studies indicate that triglyceride lowering with drugs may lead to a significant CHD reduction. Elevated blood triglycerides are associated with major alterations in the structure/function of plasma lipoproteins, which become more atherogenic, and with abnormalities in the clotting system, which may predispose to coronary thrombosis. New criteria for the classification of hypertriglyceridemias and a stepwise approach to the management of patients with elevated plasma triglycerides have been recently developed. Nonpharmacological interventions, i.e., weight reduction, alcohol and smoking cessation, and physical exercise, are the first-line actions to control hypertriglyceridemia. Drug therapy should be considered when the nonpharmacological approaches are ineffective or inadequate. Fibric acid derivatives and nicotinic acid (and its derivatives) are the drugs of choice when treating hypertriglyceridemic patients; n-3 fatty acids (fish oil) and metformin (especially in diabetic patients) represent additional therapeutic agents.

Olive oil, corn oil, and n-3 fatty acids differently affect lipids, lipoproteins, platelets, and superoxide formation in type II hypercholesterolemia.

To evaluate which dietary fat may provide the best response in terms of plasma lipids and lipoproteins and also of platelet aggregability and superoxide formation by white blood cells, 12 type II patients were randomly allocated to three different diets, which provided polyunsaturated fatty acids (corn oil), monounsaturated fatty acids (olive oil), and a supplementation of ethyl esters of n-3 fatty acids to a prudent diet. Olive oil and, more significantly, n-3 ethyl esters lowered total cholesterol best (-2.2% and -5.8%, respectively); the latter diet, as expected, also significantly lowered triglyceridemia (-21.4%). The corn-oil diet exerted a small, statistically significant reduction of high-density-lipoprotein cholesterol (HDL) (-4.3%), and it also lowered plasma total apo B concentrations (-3.8%). n-3 ethyl esters significantly raised both total (+3.1%) and particularly HDL2 cholesterol (+24%). Platelet reactivity was insignificantly reduced by the three regimens, but all three significantly reduced thrombin-stimulated formation of thromboxane B2. Finally, only the n-3 fatty acid supplementation significantly reduced O2- generation by adherent monocytes. Dietary unsaturated fatty acids are generally effective on the plasma lipid and lipoproteins in type II patients, but significant differences may be found between the three tested regimens.

Omega-3 fatty acids selectively raise high-density lipoprotein 2 levels in healthy volunteers.

The effects of omega-3 fatty acid supplementation on high-density lipoprotein (HDL) subfraction distribution and composition were evaluated in five healthy volunteers taking 2.8 g/d of eicosapentaenoic acid (EPA) and 1.7 g/d of docosahexaenoic acid (DHA) for 6 weeks. This supplementation resulted in marked changes of the plasma fatty acid composition. Plasma total cholesterol (TC), HDL-cholesterol (HDL-C), and triglyceride (TG) levels did not change. HDL2-C increased by 74%, with a concomitant 19% decrease of HDL3-C; the HDL2 to HDL3 mass ratio increased from 0.30 +/- 0.19 to 0.47 +/- 0.28. The increase of HDL2 was confirmed by nondenaturing polyacrylamide gradient gel electrophoretic separation of HDL subclasses, otherwise showing no change in HDL particle size. After omega-3 supplementation, both HDL2 and HDL3 became cholesteryl ester (CE)- and TG-enriched and free cholesterol (FC)- and phospholipid (PL)-depleted. The reported findings provide a useful adjunct to the antithrombotic potential of omega-3 fatty acids.