Plasma 27-hydroxycholesterol/cholesterol ratio is increased in low high density lipoprotein-cholesterol healthy subjects

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Sterol 27-hydroxylase converts cholesterol to 27-hydroxycholesterol (27-OHC) which is widely distributed among tissues and is expressed at high levels in the vascular endothelium and macrophages. There is a continuous flow of this oxysterol from the tissues into the liver; where it is converted to bile acids. Objective: Measure plasma concentrations of 27-OHC in subjects that differ according to their plasma HDL-C concentration. Methods: Healthy men presenting low HDL-C (1.55 mmol/L), n 18, BMI <30 kg/m(2) were recruited after excluding secondary causes that might interfere with their plasma lipid concentrations such as smoking, heavy drinking and diabetes. Blood samples were drawn after a 12 h fasting period for the measurement of 27-OHC by the combined GC/MS analysis utilizing deuterium-label internal standards. Results: The plasma ratio 27-OHC/total cholesterol (median and range nmoL/mmoL) was 50.41 (27.47-116.00) in the High HDL-C subjects and 6334 (36.46-91.18) in the Low HDL-C subjects (p = 0.0258). Conclusion: Our data indicate that the production of 27-0HC by extrahepatic tissues and its transport to the liver may represent an alternative pathway for a deficient reverse cholesterol transport system when plasma HDL-C is low. (C) 2013 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.461516191621Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)LIMHC/FMUSP (Medical Investigation Laboratories, Hospital das Clinicas/Faculty of Medical Sciences of University of Sao Paulo)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [2010/52654-6

Impact of Seasonality on the Prevalence of Dyslipidemia: A Large Population Study

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Assessment of lipid profile parameters has been considered a cornerstone in classifying individuals and populations at risk for cardiovascular disease. Recently, however, preliminary data have raised the possibility of seasonal variations in these parameters, which may cause under- or overestimation. Biological rhythms and seasonal variation of lipid profile was investigated in 227 359 consecutive individuals who underwent health checkups in primary care centers between 2008 and 2010. Plasma low-density lipoprotein cholesterol (LDL-C) >130 mg/dL was 8% more prevalent during winter than summer, with a larger difference among women and middle-aged adults (p150 mg/dL were respectively 9% and 5% more prevalent during the summer (p<0.001). Variation amplitude was 3.4 +/- 0.3 mg/dL for HDL-C (p = 0.005), 7 +/- 2 mg/dL for LDL-C (p = 0.047), and 12 +/- 9 mg/dL for TG (p = 0.058). Based on a large population sample, this study confirms the existence of biological rhythms and seasonal variation in lipid profile. This finding must be particularly accounted for in cross-sectional analyses of relative risk, prevalence, or the rate of goal achievement for lipid parameters.30810111015Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq