Triglycerides and high-density lipoprotein cholesterol are associated with insulinemia in adolescents

OBJECTIVE: The aim of this study was to evaluate the association between lipids and insulin concentration in adolescents. MATERIAL AND METHODS: A cross-sectional study of 350 adolescents aged 14-19 years old from a public high school in Guadalajara, in the state of Jalisco, Mexico, was conducted. Fasting insulin concentration was determined using microparticle enzyme immunoassay; total cholesterol and triglycerides were detected by standard enzymatic procedures;and low- and high-density lipoproteins were found using standard precipitation methods. Statistical analysis included linear multivariate regression. RESULTS: Serum triglycerides were associated positively with insulin fasting (beta = 0.003, p = 0.0001) and high-density lipoprotein cholesterol was negatively associated with insulin fasting in male adolescents 18-19 years old (beta = -0.03, p = 0.012). CONCLUSIONS: The relationships between triglycerides and insulin and between high-density lipoprotein cholesterol and insulin are already present in adolescence.     

Increased high-density lipoprotein cholesterol is associated with a high prevalence of pre-hypertension and hypertension in community-dwelling persons

The aim of this article was that high-density lipoprotein cholesterol (HDL-C) reduces blood vessel injury through its antioxidant and anti-inflammatory functions. However, the effect of HDL-C on blood pressure may be controversial. Therefore, the aim of this study was to address whether HDL-C level is associated with blood pressure, and we examined cross-sectional data from community-dwelling persons. A total of 859 men [58?±?15 (mean?±?standard deviation); 20-89 (range) (years) and 1,169 women (61?±?13; 19-88?years)] participants not on medication for hypertension were recruited from a single community at the time of their annual health examination. We examined the relationship between cardiovascular risk factors and blood pressure status. Multiple linear regression analysis using systolic blood pressure (SBP) and diastolic blood pressure (DBP) as an objective variable showed that HDL-C was significantly and independently associated with both SBP (β?=?0.138), and DBP (β?=?0.144). Compared to normotensive participants with the lowest quartile of HDL-C, multivariate-adjusted odds ratio (OR) for pre-hypertension was 1.72 (1.22-2.45) for the second quartile, 1.51 (1.07-2.15) for the third quartile, and 1.52 (1.04-2.22) for the highest quartile. Moreover, compared with normotensive participants with the lowest quartile, the multivariate-adjusted ORs for hypertension were 2.37 (1.63-3.45), 2.24 (1.54-3.28), 3.15 (2.10-4.74), respectively. There were no interactions between the two groups stratified by gender, age, BMI, drinking status, TG, FPG, and medication. Therefore, we concluded that HDL-C levels were positively associated with blood pressure in Japanese dwelling-community persons.     

Serum adiponectin is associated with high-density lipoprotein cholesterol, triglycerides, and low-density lipoprotein particle size in young healthy men

The chromosomal localization of adiponectin has been found to be mapped to human chromosome 1q21.4-1q23, a region that was identified as a susceptibility locus for familial combined hyperlipidemia and polygenic type 2 diabetes. As these 2 disorders are associated with low high-density lipoprotein (HDL)-cholesterol, high triglycerides, and insulin resistance (IR), we examined the relation of serum adiponectin concentrations to serum lipid and lipoprotein profiles as well as IR in young healthy men. Serum adiponectin levels were positively associated with HDL-cholesterol, apolipoprotein (apo) A1, and low-density lipoprotein (LDL) particle size, and negatively associated with triglycerides and apo B. Negative associations were also found between adiponectin and body mass index (BMI), percent body fat, and IR,as determined by homeostasis model assessment (HOMA). However, after adjustment for BMI, no significant associations were found between adiponectin and LDL particle size and apo B. In a multiple regression analysis including all variables that showed significant univariate associations with adiponectin, associations of adiponectin with HDL-cholesterol (beta = 0.079, P =.0009), percent body fat (beta = -0.165, P =.002), and serum leptin (beta = -0.291, P =.01) were statistically significant. HDL-cholesterol (beta = 0.077, P =.001), percent body fat (beta = -0.078, P =.03), and LDL size (beta = 0.092, P =.03) emerged as significant and independent determinants of adiponectin after HOMA IR, fasting glucose, triglycerides, and systolic blood pressure (BP) were taken into account. Together, these variables explained 19% of adiponectin variability in the 2 models. HOMA IR did not emerge as a determinant of adiponectin in both models. These findings suggest that in young healthy men hypoadiponectinemia is more closely related to adiposity and dyslipidemia than IR.     

Reduced plasma high-density lipoprotein cholesterol in hyperthyroid mice coincides with decreased hepatic adenosine 5'-triphosphate-binding cassette transporter 1 expression

The aim of the study was to investigate the influence of severe hyperthyroidism on plasma high-density lipoprotein cholesterol (HDL-C). Recently, it was shown in mice that increasing doses of T(3) up-regulate hepatic expression of scavenger receptor class B, type I, resulting in increased clearance of plasma HDL-C. Here, we show that severe hyperthyroidism in mice did not affect hepatic expression of scavenger receptor class B, type I, but reduced hepatic expression of ATP-binding cassette transporter 1, accompanied by a 40% reduction of HDL-C. The sterol content of bile, liver, and feces was markedly increased, accompanied by up-regulation of hepatic cholesterol 7alpha-hydroxylase, and ATP-binding cassette transporter 5, which is known to promote biliary sterol secretion upon dimerization with ATP-binding cassette transporter 8. Both control and hyperthyroid mice exerted identical plasma clearance of iv injected [(3)H]HDL-C, supporting the view that severe hyperthyroidism does not affect HDL-C clearance but, rather, its formation via hepatic ATP-binding cassette transporter 1.     

Clinical significance of high-density lipoprotein cholesterol in patients with low low-density lipoprotein cholesterol.

OBJECTIVES: We sought to evaluate the significance of high-density lipoprotein cholesterol (HDL-C) in the context of low low-density lipoprotein cholesterol (LDL-C). BACKGROUND: Earlier studies support an inverse correlation between circulating HDL-C and coronary risk in patients with normal or elevated LDL-C. METHODS: This study involved 4,188 patients attending the Palo Alto Veterans Administration Medical Center or affiliated clinics with LDL-C levels below 60 mg/dl. Outcomes were examined 1 year after the index LDL-C date. The combined primary end point was myocardial injury or hospitalization from ischemic heart disease. The secondary end point was all-cause mortality. RESULTS: Mean HDL-C levels (mg/dl) by quartile (Q) were: Q1 28 mg/dl, Q2 36 mg/dl, Q3 43 mg/dl, and Q4 63 mg/dl. The rate of myocardial injury or hospitalization for ischemic heart disease showed an inverse relationship to HDL-C (adjusted odds ratios: Q1 1.59 [95% confidence interval (CI) 1.16 to 2.19], Q2 1.39 [95% CI 1.01 to 1.92], Q3 1.33 [95% CI 0.96 to 1.84], and Q4 reference) that persisted regardless of statin use or recent myocardial injury. Analyzing HDL-C as a continuous variable revealed a 10% [95% CI 3% to 17%] increase in the combined end point of myocardial injury or hospitalization for ischemic heart disease for every 10-mg/dl decrease in HDL-C. The unadjusted and adjusted incidence of all-cause mortality demonstrated a U-shaped relationship to HDL-C (adjusted odds ratios: Q1 1.13 [95% CI 0.79 to 1.62], Q2 0.97 [95% CI 0.67 to 1.40], Q3 0.74 [95% CI 0.50 to 1.09], and Q4 reference). CONCLUSIONS: The inverse relationship between HDL-C and coronary risk persists even among patients with LDL-C below 60 mg/dl, although a U-shaped relationship is observed between HDL-C and all-cause mortality.     

Alcohol consumption is associated with enrichment of high-density lipoprotein particles in polyunsaturated lipids and increased cholesterol esterification rate

BACKGROUND: Alcohol consumption is associated with high levels of high-density lipoproteins (HDLs). Moreover, changes in the fatty acid patterns of red blood cell phospholipids and plasma lipids have been observed in drinkers. The objectives of this study were to characterize the composition of HDL particles with respect to lipid molecular species in regular wine drinkers and to assess the functional properties of those HDLs as regards key steps of reverse cholesterol transport. METHODS: Forty-six subjects were recruited in the frame of a population study performed in Toulouse, southern France, and a nutritional investigation, including daily alcohol consumption, was performed. Subjects were sorted according to their daily alcohol intake (0, < or =35, and >35 g/day), mostly as red wine. The plasma HDL fraction was isolated, and neutral lipid molecular lipids and phospholipid fatty acids were analyzed by gas liquid chromatography. Efflux of cellular cholesterol and rates of cholesterol esterification and cholesteryl ester transfers between lipoproteins were assayed in a cell-plasma incubation system. RESULTS: Wine drinking, at 47 g/day, was associated with an increase in HDL cholesterol and apolipoprotein A-I, but not with triglycerides. Isolated HDL displayed a 27% increase in all cholesteryl ester molecular species. The particles were also enriched in unsaturated phospholipids and, particularly, in those containing arachidonic (+30%) and eicosapentaenoic (+90%) acids. The plasma cholesterol esterification rate, reflecting lecithin cholesterol acyl transferase activity on HDL, was found to be higher (+27%) in drinkers than in nondrinkers, whereas the rate of cellular cholesterol efflux to plasma was identical. CONCLUSIONS: Regular wine consumption is associated with high levels of polyunsaturated lipids in HDL and with increases in the cholesterol esterification rate.     

易成石和抗成石小鼠肝脏胆固醇代谢调节酶的基因表达特征

目的通过研究胆囊胆固醇结石易成石小鼠(C57L鼠)和抗成石小鼠(AKR鼠)肝脏胆固醇代谢调节酶的基因表达差异来探讨胆囊胆固醇结石形成的分子机制.方法用致石饲料(含15%脂肪、1.25%胆固醇和0.5%胆酸)喂养C57L和AKR鼠4周,分别在喂养前、后检查其肝脏重量、肝脏胆固醇含量和胆囊内结石形成情况,并用RT-PCR法分析参与肝脏胆固醇代谢调节的肝脏3羟基3甲基-戊二酰辅酶A还原酶(HMG-CoAR)、胆固醇7α羟化酶(C7H)、乙酰基辅酶A-胆固醇酰基转移酶(ACAT)和低密度脂蛋白受体(LDLR)的mRNA含量.结果致石饲料喂养前、后AKR鼠肝脏胆固醇含量均明显高于C57L鼠,致石饲料诱导4周后C57L鼠胆囊内有胆固醇结石形成,而AKR鼠则无.致石饲料诱导前AKR鼠肝脏HMG-CoAR的mRNA表达水平明显高于C57L鼠,而ACAT、LDLR、C7H的mRNA水平在两组小鼠间差异无统计学意义(P＞0.05).致石饲料诱导后,AKR鼠肝脏HMG-CoAR和C7H的mRNA水平分别下降31%和30%,但C57L鼠无明显改变,其中AKR和C57L鼠肝脏LDLR的mRNA表达水平则分别提高14%和41%.结论致石饲料作为一种环境因素能揭示C57L和AKR鼠肝脏胆固醇代谢调节酶的基因表达特征.致石饲料诱导后C57L鼠肝脏HMGCoAR基因表达水平的下调不足和LDLR基因表达水平的显著上升可能在其胆囊胆固醇结石形成过程中发挥着一定作用.     

Significance of high-density lipoprotein cholesterol.

The central importance of elevated blood cholesterol levels in the process of atherosclerotic heart disease (ASHD) is firmly established. Cholesterol is transported in the blood in conjunction with protein as a lipoprotein complex. The low-density lipoproteins (LDL) carry the bulk of the blood cholesterol. The high-density lipoproteins (HDL) occur in much smaller amounts. Recently it has been demonstrated that not only is the cholesterol carried in the HDL fraction not harmful, but appears to be protective against the development of ASHD. Data from Framingham and elsewhere seem consistent with this observation. The HDS apparently represent the fraction concerned with the efflux of cholesterol from the tissues, so that higher levels may represent a heightened cholesterol-riddance mechanism. Thus far, two circumstances seem to be associated with elevated levels of HDL--physical exercise and ethanol ingestion. The importance of these observations in the clinical management of the patient at risk is discussed.     

Increased monocyte to high-density lipoprotein cholesterol ratio is associated with TIMI risk score in patients with ST-segment elevation myocardial infarction

Introduction and Aim

The monocyte to high-density lipoprotein cholesterol ratio (MHR) has recently been proposed as a new predictor and prognostic indicator in cardiovascular disease. The TIMI risk score predicts short-term mortality in ST-elevation myocardial infarction (STEMI) patients. However, there have been no studies regarding the association between MHR and TIMI score in patients with STEMI.

Comparison of low-density lipoprotein cholesterol/high-density lipoprotein cholesterol and total cholesterol/high-density lipoprotein cholesterol for the prediction of thin-cap fibroatheroma determined by intravascular optical coherence tomography

BackgroundThe correlation among the ratios of low-density lipoprotein cholesterol/high-density lipoprotein cholesterol (LDL-C/ HDL-C), total cholesterol/high-density lipoprotein cholesterol (TC/HDL-C) and thin-cap fibroatheroma has not yet been established.MethodsIt was a single center, retrospective observational study. In total, we recruited 421 patients (82.4% men; mean age 65.73 ± 10.44 years) with one culprit vessel which determined by intravascular optical coherence tomography (OCT). The thinnest-capped fibroatheroma (TCFA) group was defined as lipid contents in > 2 quadrants, with the thinnest fibrous cap measuring less than 65 μm. Univariate and multivariate logistic regression were carried out to explore the relationship between lipoprotein ratios, TCFA and other characteristics of plaque. To compare different ratios, the area under curve (AUC) of receiver-operating characteristic (ROC) curve was assessed.ResultsOCT was performed in 421 patients (TCFA group (n = 109), non-TCFA group (n = 312)). LDL-C/HDL-C in the TCFA group was significantly higher than in the non-TCFA group (2.95 ± 1.20 vs. 2.43 ± 0.92, P < 0.05), as was TC/LDL in TCFA and non-TCFA group (4.57 ± 1.58 vs. 4.04 ± 1.13, P < 0.05). Both LDL-C/HDL-C (OR: 1.002 (1.002-1.003), P < 0.05) and TC/HDL-C (OR: 1.001 (1.001-1.004), P < 0.05) were considered independent factors for the prediction of TCFA according to the logistic regression. Based on the AUC comparison, LDL-C/ HDL-C and TC/HDL-C had no significant difference statistically (LDL-C/HDL-C AUC: 0.63; TC/HDL-C AUC: 0.61; P = 0.10) for the prediction of TCFA.ConclusionsLDL-C/HDL-C and TC/HDL-C could be the independent factors for predicting the presence of TCFA, indicating coronary plaque vulnerability in CAD patients. Moreover, TC/HDL-C also showed a comparative performance for the prediction of TCFA as LDL-C/HDL-C.     

Effects of hepatic expression of the high-density lipoprotein receptor SR-BI on lipoprotein metabolism and female fertility

The etiology of human female infertility is often uncertain. The sterility of high-density lipoprotein (HDL) receptor-negative (SR-BI(-/-)) female mice suggests a link between female infertility and abnormal lipoprotein metabolism. SR-BI(-/-) mice exhibit elevated plasma total cholesterol [with normal-sized and abnormally large HDL and high unesterified to total plasma cholesterol (UC:TC) ratio]. We explored the influence of hepatic SR-BI on female fertility by inducing hepatic SR-BI expression in SR-BI(-/-) animals by adenovirus transduction or stable transgenesis. For transgenes, we used both wild-type SR-BI and a double-point mutant, Q402R/Q418R (SR-BI-RR), which is unable to bind to and mediate lipid transfer from wild-type HDL normally, but retains virtually normal lipid transport activities with low-density lipoprotein. Essentially wild-type levels of hepatic SR-BI expression in SR-BI(-/-) mice restored to nearly normal the HDL size distribution and plasma UC:TC ratio, whereas approximately 7- to 40-fold overexpression dramatically lowered plasma TC and increased biliary cholesterol secretion. In contrast, SR-BI-RR overexpression had little effect on SR-BI(+/+) mice, but in SR-BI(-/-) mice, it substantially reduced levels of abnormally large HDL and normalized the UC:TC ratio. In all cases, hepatic transgenic expression restored female fertility. Overexpression in SR-BI(-/-) mice of lecithin:cholesterol acyl transferase, which esterifies plasma HDL cholesterol, did not normalize the UC:TC ratio, probably because the abnormal HDL was a poor substrate, and did not restore fertility. Thus, hepatic SR-BI-mediated lipoprotein metabolism influences murine female fertility, raising the possibility that dyslipidemia might contribute to human female infertility and that targeting lipoprotein metabolism might complement current assisted reproductive technologies.     

Severe high-density lipoprotein deficiency associated with autoantibodies against lecithin:cholesterol acyltransferase in non-Hodgkin lymphoma

An antibody against the lecithin:cholesterol acyltransferase (LCAT) enzyme, which negates cholesterol esterification in plasma, causing severe high-density lipoprotein deficiency (HD), was identified in a woman with a large-cell non-Hodgkin lymphoma. Successful treatment of the lymphoma resulted in clearance of the antibody and complete correction of the defective cholesterol esterification and HD. To our knowledge, an acquired LCAT deficiency leading to severe HD has not been reported previously in association with a malignant disease, and this patient represents the first such documented case.     

Low high-density lipoprotein cholesterol is a residual risk factor associated with long-term clinical outcomes in diabetic patients with stable coronary artery disease who achieve optimal control of low-density lipoprotein cholesterol

Diabetes mellitus is recognized an independent risk factor for coronary artery disease (CAD) and mortality. Clinical trials have shown that statins significantly reduce cardiovascular events in diabetic patients. However, residual cardiovascular risk persists despite the achievement of target low-density lipoprotein cholesterol (LDL-C) levels with statin. High-density lipoprotein cholesterol (HDL-C) is an established coronary risk factor that is independent of LDL-C levels. We evaluated the impact of HDL-C on long-term mortality in diabetic patients with stable CAD who achieved optimal LDL-C. We enrolled 438 consecutive diabetic patients who were scheduled for percutaneous coronary intervention between 2004 and 2007 at our institution. We identified 165 patients who achieved target LDL-C <100 mg/dl. Patients were stratified into two groups according to HDL-C levels (low HDL-C group, baseline HDL-C <40 mg/dl; high HDL-C group, ≥40 mg/dl). Major adverse cardiac events (MACE) that included all-cause death, acute coronary syndrome, and target lesion revascularization were evaluated between the two groups. The median follow-up period was 946 days. The rate of MACE was significantly higher in diabetic patients with low-HDL-C who achieved optimal LDL-C (6.9 vs 17.9 %, log-rank P = 0.030). Multivariate Cox regression analysis showed that HDL-C is significantly associated with clinical outcomes (adjusted hazard ratio for MACE 1.33, 95 % confidence interval 1.01–1.75, P = 0.042). Low HDL-C is a residual risk factor that is significantly associated with long-term clinical outcomes among diabetic patients with stable CAD who achieve optimal LDL-C levels.