Determination Of High-density Lipoprotein Cholesterol Research Articles

Dietary fat modulation of hepatic lipase variant -514 C/T for lipids: a crossover randomized dietary intervention trial in Caribbean Hispanics.

The hepatic lipase (LIPC) locus is a well-established determinant of high-density lipoprotein cholesterol (HDL-C) concentrations, an association that is modified by dietary fat in observational studies. Dietary interventions are lacking. We investigated dietary modulation of LIPC rs1800588 (-514 C/T) for lipids and glucose using a randomized crossover design comparing a high-fat Western diet and a low-fat traditional Hispanic diet in individuals of Caribbean Hispanic descent (n = 42, 4 wk/phase). No significant gene-diet interactions were observed for HDL-C. However, differences in dietary response according to LIPC genotype were observed. In major allele carriers (CC/CT), HDL-C (mmol/l) was higher following the Western diet compared with the Hispanic diet: phase 1 (Western: 1.3 ± 0.03; Hispanic: 1.1 ± 0.04; P = 0.0004); phase 2 (Western: 1.4 ± 0.03; Hispanic: 1.2 ± 0.03; P = 0.0003). In contrast, HDL-C in TT individuals did not differ by diet. Only major allele carriers benefited from the higher-fat diet for HDL-C. Secondarily, we explored dietary fat quality and rs1800588 for HDL-C and triglycerides (TG) in a Boston Puerto Rican Health Study (BPRHS) subset matched for diabetes and obesity status (subset n = 384). In the BPRHS, saturated fat was unfavorably associated with HDL-C and TG in rs1800588 TT carriers. LIPC rs1800588 appears to modify plasma lipids in the context of dietary fat. This new evidence of genetic modulation of dietary responses may inform optimal and personalized dietary fat advice and reinforces the importance of studying genetic markers in diet and cardiometabolic health.

The evolution of selective analyses of HDL and LDL cholesterol in clinical and point of care testing

Cardiovascular disease is a leading cause of death worldwide and is caused by the build up of atherosclerotic plaques in the vasculature. It is now well established that the formation of these plaques is closely related to levels of both high density lipoprotein (HDL) and low density lipoprotein (LDL) cholesterol. Thus, the importance of the effective measurement of these is critical for the improved diagnosis and management of atherosclerosis. This review discusses the emergence of methodologies for the selective determination of both LDL and HDL cholesterol. It begins with an explanation of the first methodologies based on ultracentrifugation and precipitation techniques, the development of reference methods, through to the emergence of methodologies suitable for routine laboratory use, followed by the development of professional use, point of care technologies. Finally, the current status of selective tests for cholesterol based on biosensor methodologies is reviewed and the potential for application in consumer diagnostics is discussed.

Multidimensional profiling of plasma lipoproteins by size exclusion chromatography followed by reverse-phase protein arrays

The composition of lipoproteins and the association of proteins with various particles are of much interest in the context of cardiovascular disease. Here, we describe a technique for the multidimensional analysis of lipoproteins and their associated apolipoproteins. Plasma is separated by size exclusion chromatography (SEC), and fractions are analyzed by reverse-phase arrays. SEC fractions are spotted on nitrocellulose slides and incubated with different antibodies against individual apolipoproteins or antibodies against various apolipoproteins. In this way, tens of analytes can be measured simultaneously in 100 μl of plasma from a single SEC separation. This methodology is particularly suited to simultaneous analysis of multiple proteins that may change their distribution to lipoproteins or alter their conformation, depending on factors that influence circulating lipoprotein size or composition. We observed changes in the distribution of exchangeable apolipoproteins following addition of recombinant apolipoproteins or interaction with exogenous compounds. While the cholesteryl ester transfer protein (CETP)-dependent formation of pre-β-HDL was inhibited by the CETP inhibitors torcetrapib and anacetrapib, it was not reduced by the CETP modulator dalcetrapib. This finding was elucidated using this technique.

Abstract 9712: Lack of Association Between Common p.T111I Variant in the Endothelial Lipase Gene and the Risk for Coronary Artery Disease in Familial Hypercholesterolemia: Insights From the Modulation of Phospholipids in the HDL Particles

Background: endothelial lipase (EL) is a major determinant of high-density lipoprotein cholesterol (HDL-C) metabolism through the lipolysis of the phospholipids (PL) in the HDL particles (HDL-PL). Several studies indicated that common p.T111I variant in EL gene (LIPG: rs2000813) is negatively associated with the risk of coronary artery disease (CAD) independent of HDL-C levels. However, few data exist regarding the influence of this variant on the content of HDL-PL in terms of the association with CAD, especially in familial hypercholesterolemia (FH) subjects. The aim of our study is to elucidate the clinical impact of common p.T111I variant in the EL gene on the content of HDL-PL, and whether this variant could be useful predictor of the risk of CAD in FH subjects, which always exhibit low HDL-C levels. Methods: The p.T111I variant was genotyped in our heterozygous FH subjects (n=80, male=56, mean age=64±18yr, mean TC=340±64mg/dl). All those subjects' plasma lipoproteins were investigated by ultracentrifugation method. Overall HDL-C level, HDL-PL level, and the existence of CAD were investigated for each group (TT group vs. TI and II group). Results: The minor allele frequency in the combined pools of subjects was 0.25. There was no significant association between this variant with overall HDL-C level (42±14 vs. 43±17mg/dl, p=NS) nor with HDL-PL level (86±24 vs. 88±27mg/dl, p=NS). In addition, multiple logistic regression analysis revealed no association between this variant and CAD (odds ratio 0.96, 95%CI:0.88-1.04, p=NS) although significant associations between several coronary risk factors and CAD were observed (figure). Conclusions: These data suggest that common p.T111I variant in LIPG neither plays a role in determining HDL-C as well as HDL-PL levels nor is a useful predictor of the risk of CAD in genetically determined heterozygous FH subjects.

Association of the LIPG 584C > T polymorphism and serum lipid levels in the Guangxi Bai Ku Yao and Han populations

BackgroundEndothelial lipase (EL) is a major determinant of high-density lipoprotein-cholesterol (HDL-C) metabolism, but the association of endothelial lipase gene (LIPG) polymorphism and serum HDL-C levels is scarce and conflicting in diverse populations. Bai Ku Yao is an isolated subgroup of the Yao minority in China. This study was designed to detect the association of LIPG 584C > T (rs2000813) polymorphism and several environmental factors with serum lipid levels in the Guangxi Bai Ku Yao and Han populations.MethodsA total of 645 subjects of Bai Ku Yao and 638 participants of Han Chinese were randomly selected from our previous stratified randomized cluster samples. Genotyping of the LIPG 584C > T was performed by polymerase chain reaction and restriction fragment length polymorphism combined with gel electrophoresis, and then confirmed by direct sequencing.ResultsThe levels of serum total cholesterol (TC), HDL-C, low-density lipoprotein cholesterol (LDL-C) and apolipoprotein (Apo) AI and ApoB were lower in Bai Ku Yao than in Han (P < 0.05 - 0.001). The frequency of C and T alleles was 73.5% and 26.5% in Bai Ku Yao, and 67.9% and 32.1% in Han (P < 0.01); respectively. The frequency of CC, CT and TT genotypes was 50.4%, 46.2% and 3.4% in Bai Ku Yao, and 41.4%, 53.1% and 5.5% in Han (P < 0.01); respectively. Serum HDL-C levels in both ethnic groups were different among the three genotypes (P < 0.05 for each). Serum TC levels in both ethnic groups were also different between the CC and CT/TT genotypes (P < 0.05 for each). The T allele carriers had higher serum HDL-C and TC levels than the T allele noncarriers. Multivariate logistic regression analysis showed that the levels of HDL-C and ApoB were correlated with genotypes in Bai Ku Yao (P < 0.05 for each), whereas the levels of TC and HDL-C were associated with genotypes in Han Chinese (P < 0.05 and P < 0.01). Serum lipid parameters were also correlated with several environmental factors in the both ethnic groups.ConclusionsThe frequency of LIPG 584T allele is lower in Bai Ku Yao than in Han Chinese. The LIPG 584T allele is associated with increased serum HDL-C, TC and ApoB levels. The differences in serum HDL-C, TC and ApoB levels between the two ethnic groups might partly result from different genotypic and allelic frequencies of LIPG 584C > T or different LIPG-enviromental interactions.

Paradoxically high adiponectin and the healthy obese phenotype in obese black and white 16-year-old girls

Although adiponectin is correlated inversely with obesity, some obese adults without metabolic complications of obesity have paradoxically high adiponectin. Therefore, we assessed adiponectin risk factor relations in 133 obese 16-year-old school girls from a cohort of 448, focusing on paradoxically high adiponectin-risk in obesity and the healthy obese phenotype. Median adiponectin (11.9 mg/L) in nonobese girls (body mass index [BMI] < 24.6 kg/m²) was selected as a cutpoint to identify high adiponectin in obese girls. Of 90 black and 43 white obese girls (BMI ≥ 24.6), 25 black (28%) and 13 white (30%) girls had paradoxically high adiponectin (>11.9). The 38 obese girls with adiponectin >11.9 versus the 95 obese girls with adiponectin ≤11.9 had higher median high-density lipoprotein (HDL) cholesterol (54 vs 46 mg/dL, P = 0.0007) and apolipoprotein A1 (ApoA1) (181 vs 164 mg/dL, P = 0.011) and had lower insulin (14 vs 20 uU/mL, P = 0.0006). In the 133 obese girls, through stepwise regression, the adiponectin category (>11.9, ≤ 11.9 mg/L) was a significant independent positive determinant of HDL cholesterol (partial r² = 8.4%, P = 0.001), ApoA1 (partial r² = 4.1%, P = 0.025), and it was associated inversely with fasting serum insulin (partial r² = 5.4%, P = 0.0074). By stepwise logistic regression in the 133 obese girls, the adiponectin category (high vs low) was a significant inverse explanatory variable for metabolic syndrome (odds ratio 0.20, 95% confidence intervals 0.04-0.95, P = 0.043). We conclude that paradoxically high adiponectin is associated with the healthy obese phenotype in obese adolescent black and white girls.

Obesity-Induced Lymphocyte Hyperresponsiveness to Chemokines: A New Mechanism of Fatty Liver Inflammation in Obese Mice

Hepatic lipid retention (steatosis) predisposes hepatitis. We investigated the mechanisms of lymphocyte homing to fatty liver and the role of lipopolysaccharide (LPS) in the onset of inflammation in ob/ob mice. We decreased intestinal bacterial compounds by oral antibiotic treatment to test the role of endogenous LPS in liver inflammation. Adoptive transfer of lymphocytes was used to study the respective contributions of steatosis and lymphocytes to liver inflammation. We tested lymphocyte response to chemokines by in vitro chemotaxis assays in ob/ob, their lean controls, and "non-obese ob/ob" mice, generated by controlling caloric intake to distinguish between the effects of obesity and leptin deficiency. Antibiotic treatment decreased liver infiltration with CD4(+) T, CD8(+) T, natural killer (NK)T, B, and NK cells. Adoptive transfer of lymphocytes from ob/ob or control mice showed that (1) steatosis increased lymphocyte recruitment to the liver; (2) CD4(+) T, CD8(+) T, and B cells from ob/ob mice had a greater propensity to migrate specifically to the liver. This migration was enhanced by LPS. These results were also observed in a model of high-fat diet-induced obesity. CD4(+) T and B cells were hyperresponsive to CXCL12 and CXCL13, respectively. Weight normalization in "non-obese ob/ob" mice decreased liver inflammation, lymphocyte response to chemokines, and homing to the liver. Our study provides the first evidence that liver inflammation in mice with genetic or diet-induced obesity results from both steatosis and lymphocyte hyperresponsiveness to chemokines expressed in the liver. These abnormalities are reversible with weight normalization.

Endothelial Lipase Gene Polymorphism is Associated With Acute Myocardial Infarction, Independently of High-Density Lipoprotein-Cholesterol Levels

Endothelial lipase (EL) is a major determinant of high-density lipoprotein-cholesterol (HDL-C) metabolism and promotes monocytes recruitment. The local expression of EL could influence atherogenesis directly, in addition to its systemic role in HDL metabolism. The EL gene has a common 584C/T polymorphism, but it is unclear whether this polymorphism is associated with HDL-C levels or acute myocardial infarction (AMI). A case-control study of 107 AMI patients and 107 control subjects was conducted. T allele frequency was lower in the AMI group than in controls (0.18 vs 0.26, p<0.05). No significant association was found between the 584C/T polymorphism and HDL-C levels. Multivariate regression analyses showed that the association of the T allele with AMI was statistically significant and independent of other risk factors when age, sex, hypertension, hypercholesterolemia, and diabetes mellitus were included in the analyses (odds ratio (OR), 0.52; 95% confidence interval (95% CI) 0.28-0.98; p=0.04). However, when smoking status was included, the association of the T allele with AMI did not remain statistically significant (OR, 0.61; 95% CI 0.32-1.18; p=0.14). The 584C/T polymorphism of the EL gene was associated with AMI independently of HDL-C levels and thus may be involved in the pathogenesis of AMI.

One third of the variability in HDL‐cholesterol level in a large dyslipidaemic population is predicted by age, sex and triglyceridaemia:The Paris La Pitié Study

ABSTRACTObjective: The objective of this study was to identify key determinants of high-density lipoprotein-cholesterol (HDL-C) level, including subclinical inflammation and insulin resistance, and to determine the prevalence of a low HDL-C phenotype in dyslipidaemic patients at high cardiovascular risk.Methods: In a cross-sectional study, we assessed the prevalence of low HDL‐C phenotypes in 14 667 dyslipidaemic patients attending our specialised lipid clinic and evaluated the potential relationships between HDL‐C level and 16 clinical and biological parameters.Results: In univariate analysis, women exhibited higher plasma concentrations of HDL‐C as compared with men. Levels of triglycerides, fasting blood glucose, uric acid, waist circumference, body mass index, high sensitivity C-reactive protein (hs‐CRP), insulin resistance (as HOMA‐IR index) and smoking were all negatively correlated with HDL‐C, whereas age was positively correlated with HDL‐C levels. Moderate drinkers (10–30 g/day) displayed higher HDL‐C concentrations as compared with abstinent subjects; in contrast, consumption of more than 30 g alcohol/day was associated with a further non-significant elevation of HDL‐C levels as compared to moderate drinkers. Multivariate analysis identified eight independent correlates of HDL‐C. Age, sex and TG accounted for 37% of variability in HDL‐C; modifiable factors including waist circumference, alcohol consumption and smoking, in addition to HOMA‐IR and hs‐CRP, accounted for an additional 5% of the variability in HDL‐C. Using a cut-off of 40 mg/dL (1.03 mmol/L) for men and 50 mg/dL (1.29 mmol/L) for women, 33% and 28% of men and women displayed low levels of HDL‐C.Conclusion: Eight independent determinants of HDL‐C account for 41% of variability in HDL‐C in our dyslipidaemic population. Three of them, i.e. age, sex and degree of triglyceridaemia accounted for more than one third of such variability. The high prevalence of low HDL‐C phenotypes in dyslipidaemic patients at elevated cardiovascular risk emphasises the need for both lifestyle and pharmacological strategies of intervention to raise HDL‐C.

Zinc Finger Protein 202, genetic variation, and HDL cholesterol in the general population

Zinc Finger Protein 202 (ZNF202) is a transcriptional repressor that binds elements found predominantly in genes involved in HDL metabolism. We tested the following hypotheses: 1) frequencies of single-nucleotide polymorphisms (SNPs) and haplotypes in ZNF202 differ between individuals with low and high HDL cholesterol; and 2) SNPs in ZNF202 affect HDL cholesterol levels in the general population. We screened the promoter and protein-coding exons of ZNF202 in individuals with the highest 1% (n = 95) and lowest 1% (n = 95) HDL cholesterol among 9,259 Danish adults. None of the 10 SNPs identified differed in frequency as single sites or as haplotypes between low and high HDL cholesterol groups. In accordance with this, seven mutations were equally frequent (4-5%) in individuals with low or high HDL cholesterol. Finally, for all five SNPs identified in the coding region, we determined the association of genotype with HDL cholesterol in 9,259 individuals from the general population. Four SNPs were not associated with variation in HDL cholesterol, although c.*2T>G homozygosity was associated with a discrete effect on HDL cholesterol in men. We show that genetic variation in ZNF202 is common in the general population. However, SNPs in the protein-coding region of ZNF202 do not make a major contribution to HDL cholesterol levels.

Benefits of Niacin in Patients With Versus Without the Metabolic Syndrome and Healed Myocardial Infarction (from the Coronary Drug Project)

This post hoc analysis from the Coronary Drug Project (CDP) evaluated the effects of niacin monotherapy on clinical outcomes in patients with and without the metabolic syndrome (MS). The CDP was a randomized, placebo-controlled clinical trial of lipid-modifying agents in men with previous myocardial infarction (MI). Of the 5 drug regimens, only niacin significantly decreased definite recurrent nonfatal MI at 6 years and total mortality at a 15-year follow-up. Patients treated with niacin (n = 1,119) and placebo (n = 2,787) were grouped according to the presence or absence of the MS at baseline. The MS was defined on the basis of meeting > or =3 of 5 criteria from the current National Cholesterol Education Program guidelines in a small subgroup of patients with high-density lipoprotein cholesterol determinations at baseline and on the basis of > or =3 of 4 criteria in the total population, excluding the high-density lipoprotein cholesterol criterion. Niacin decreased the occurrence of 6-year MI and 15-year total mortality similarly among patients with or without the MS. For example, in the total population, 15-year total mortality rates were 60% and 64% (hazard ratio 0.86) in patients with the MS treated with niacin and placebo, respectively, and 50% and 57% (hazard ratio 0.86) in those without the MS (Z for interaction = 0.06, indicating homogeneity of the treatment effect across groups). In conclusion, these results support the use of niacin in postinfarction patients with and without the MS.

Endothelial lipase modulates HDL but has no effect on atherosclerosis development in apoE−/− and LDLR−/− mice

Endothelial lipase (EL) is a determinant of high density lipoprotein-cholesterol (HDL-C) level, which is negatively correlated with atherosclerosis susceptibility. We found no difference in aortic atherosclerotic lesion areas between 26-week-old EL+/+ apolipoprotein E-deficient (apoE-/-) and EL-/- apoE-/- mice. To more firmly establish the role of EL in atherosclerosis, we extended our study to EL-/- and EL+/+ low density lipoprotein receptor-deficient (LDLR-/-) mice that were fed a Western diet. Morphometric analysis again revealed no difference in atherosclerosis lesion area between the two groups. Compared with EL+/+ mice, we found increased HDL-C in EL-/- mice with apoE-/- or LDLR-/- background but no difference in macrophage content between lesions of EL-/- and EL+/+ mice in apoE-/- or LDLR-/- background. EL inactivation had no effect on hepatic mRNAs of proteins involved in reverse cholesterol transport. A survey of lipid homeostasis in EL+/+ and EL-/- macrophages revealed that oxidized LDL-induced ABCA1 was attenuated in EL-/- macrophages. This potentially proatherogenic change may have nullified any minor protective increase of HDL in EL-/- mice. Thus, although EL modulated lipoprotein profile in mice, there was no effect of EL inactivation on atherosclerosis development in two hyperlipidemic atherosclerosis-prone mouse models.

The “Good Cholesterol”

Atherosclerosis is an insidious and dangerous disease: a progressive chemical and structural injury to the blood vessels in such critical organs as the heart, brain, and kidney. The hallmark feature of atherosclerosis is the buildup of cholesterol into lesions called plaques that can reduce the flow of blood. When the delivery of blood to heart muscle drops enough, this can result in the development of chest pain or angina. Angina indicates that the heart muscle is not receiving enough oxygen to carry out its pumping functions. Atherosclerotic plaques can also suddenly rupture, develop a blood clot on their surface, and completely choke off a portion of heart muscle. This chain of events frequently results in heart attack or sudden death without warning. Atherosclerotic disease also predisposes people to stroke, peripheral vascular disease, lower-extremity amputation, and loss of kidney function, among other devastating outcomes. Despite all that we have learned in the past 50 years, atherosclerosis remains the No. 1 killer of men and women and the chief reason for loss of quality of life in Western countries. We are, however, gaining ground. Considerable research has revealed the importance of factors that increase an individual’s risk for developing this disease. Among the most important of these risk factors are elevated blood pressure, diabetes mellitus, obesity, inactivity, smoking, and cholesterol levels. When your physician measures your cholesterol level, he or she is looking at your lipid profile, which comprises low-density lipoprotein cholesterol (LDL-C, or the “bad” cholesterol), triglycerides (blood fats), and high-density lipoprotein cholesterol (HDL-C, or the “good” cholesterol). In a general way, when it comes to measurement of your LDL-C and triglyceride values, a lower value is better because these lipids drive the development and progression of atherosclerosis. In sharp contrast, when it …

Novel QTLs for HDL levels identified in mice by controlling for Apoa2 allelic effects: confirmation of a chromosome 6 locus in a congenic strain.

Atherosclerosis is a complex disease resulting from the interaction of multiple genes, including those causing dyslipidemia. Relatively few of the causative genes have been identified. Previously, we identified Apoa2 as a major determinant of high-density lipoprotein cholesterol (HDL-C) levels in the mouse model. To identify additional HDL-C level quantitative trait loci (QTLs), while controlling for the effect of the Apoa2 locus, we performed linkage analysis in 179 standard diet-fed F(2) mice derived from strains BALB/cJ and B6.C-H25(c) (a congenic strain carrying the BALB/c Apoa2 allele). Three significant QTLs and one suggestive locus were identified. A female-specific locus mapping to chromosome 6 (Chr 6) also exhibited effects on plasma non-HDL-C, apolipoprotein AII (apoAII), apoB, and apoE levels. A Chr 6 QTL was independently isolated in a related congenic strain (C57BL/6J vs. B6.NODc6: P = 0.003 and P = 0.0001 for HDL-C and non-HDL-C levels, respectively). These data are consistent with polygenic inheritance of HDL-C levels in the mouse model and provide candidate loci for HDL-C and non-HDL-C level determination in humans.

Lifestyle determinants of high-density lipoprotein cholesterol: the National Heart, Lung, and Blood Institute Family Heart Study

Background While genetic factors are major determinants of high-density lipoprotein cholesterol (HDL-C), environmental factors also play a role. The latter include 3 modifiable lifestyle factors: alcohol consumption, physical activity, and smoking. Methods We compared the relative effects of alcohol, physical activity, and smoking on HDL-C levels, using data from 2309 subjects (1226 women and 1083 men), aged 25 to 91 years, from randomly selected families participating in the National Heart, Lung, and Blood Institute Family Heart Study. Results Alcohol consumption was associated with the largest increment in HDL-C (an increase of 9.0–13.1 mg/dL from nondrinker to highest categories); physical activity with a more modest increment (an increase of 3.0–3.3 mg/dL from lowest to highest categories); and cigarette smoking with a large decrement in women (a decrease of 9.9 mg/dL) and a modest one in men (a decrease of 2.6 mg/dL) between nonsmoker and ≥20 cigarettes per day categories. The 3 lifestyle behaviors plus age, body mass index, education, and current estrogen use explained 22.4% and 18.2% of the total variance of HDL-C for women and men, respectively. Alcohol accounted for 28.6% of this variance among women and 50.1% among men; smoking accounted for 6.7% and 3.3%, respectively, and physical activity for 2.7% and 3.6%, respectively, among women and men. Age, body mass index, education, and current estrogen use explained the remaining 62.0% and 43.0%, respectively, of the variance attributed to environmental factors. Conclusions This study suggests that, among lifestyle behaviors, alcohol consumption is the more important correlate of HDL-cholesterol.

Usefulness of non–high-density lipoprotein cholesterol determinations in the diagnosis and treatment of dyslipidemia

Non–high-density lipoprotein (non-HDL) cholesterol, calculated as total cholesterol minus high-density lipoprotein (HDL) cholesterol, encompasses the apolipoprotein B (Apo B)–containing particles that promote atherosclerosis, including low-density lipoprotein (LDL) cholesterol, very-low-density lipoprotein (VLDL) cholesterol, lipoprotein (a), and intermediate-density lipoprotein cholesterol; therefore, it may represent an accurate marker for coronary heart disease (CHD) risk. The Adult Treatment Panel (ATP) III guidelines have introduced non-HDL cholesterol as a secondary target of therapy for patients with elevated levels of triglycerides.1 The aim of this review was to compare LDL and non-HDL cholesterol as markers of atherosclerotic disease and to discuss treatment options for reducing non-HDL cholesterol.

Interaction between the Gln–Arg 192 variants of the paraoxonase gene and oleic acid intake as a determinant of high-density lipoprotein cholesterol and paraoxonase activity

Olive oil, rich in oleic acid, could play a particular beneficial role in the anti-atherogenic effects attributed to the Mediterranean diet. Paraoxonase (PON1) has emerged as the component of high-density lipoproteins (HDL) most likely to explain its ability to attenuate the oxidation of low-density lipoproteins. We hypothesised that oleic acid intake might be associated with changes in PON1–HDL associated particles, and investigated the impact, if any, on this association of the PON1–192 polymorphism, a common polymorphism that strongly modulates PON1 activity. Six hundred and fifty-four men randomly selected from the census were studied. Oleic acid intake was calculated from a 72-h recall questionnaire with specific software. Oleic acid intake groups (low vs. high) were created by stratifying the population according the median value as a cut-point. After adjusting for confounding variables, high oleic acid intake was associated with increased HDL cholesterol levels and PON1 activity only in subjects with the QR and the RR genotypes, respectively. Analyses of the variance showed a statistically significant interaction between PON1–192 genotypes and oleic acid intake for log PON1 activity ( P=0.005) and a marginally significant interaction for HDL cholesterol ( P=0.066). These results suggest that the beneficial effect of increasing oleic acid intake on HDL and PON1 activity at population level is especially observed in subjects carrying the R allele of the PON1–192 polymorphism.

Common and Rare ABCA1 Variants Affecting Plasma HDL Cholesterol

Mutations in ABCA1, a member of the ATP-binding cassette family, have been shown to underlie Tangier disease (TD) and familial hypoalphalipoproteinemia (FHA), which are genetic disorders that are characterized by depressed concentrations of plasma high density lipoprotein (HDL) cholesterol. An important question is whether common variants within the coding sequence of ABCA1 can affect plasma HDL cholesterol in the general population. To address this issue, we developed a screening strategy to find common ABCA1 variants. This strategy involved long-range amplification of genomic DNA by using coding sequences only, followed by deep sequencing into the introns. This method helped us to characterize a new set of amplification primers, which permitted amplification of virtually all of the coding sequence of ABCA1 and its intron-exon boundaries with a single DNA amplification program. With these new sequencing primers, we found 3 novel ABCA1 mutations: a frameshift mutation (4570insA, A1484S-->X1492), a missense mutation (A986D) in a TD family, and a missense mutation (R170C) in aboriginal subjects with FHA. We also used these sequencing primers to characterize 4 novel common amino acid variants in ABCA1, in addition to 5 novel common silent variants. We tested for association of the ABCA1 I/M823 variant with plasma HDL cholesterol in Canadian Inuit and found that M823/M823 homozygotes had significantly higher plasma HDL cholesterol compared with subjects with the other genotypes. The results provide proof of principle of the effectiveness of this approach to identify both rare and common ABCA1 genomic variants and also suggest that common amino acid variation in ABCA1 is a determinant of plasma HDL cholesterol in the general population.

Méthodes de dosage du Cholestérol HDL en phase homogène. Essai comparatif de quatre coffrets

Homogeneous assays for direct determination of High-density lipoprotein cholesterol. Performance study of four reagents. Four reagents have been evaluated for HDL Cholesterol determination, an important risk factor for coronary heart disease. These homogeneous assays involved three different procedures: sulfated α-cyclodextrin and PEG-modified enzymes (Roche-Boehringer ® et Randox ®), anti-human apo B antibodies (Sigma®) and polyanion/synthetic polymer (bioMérieux ®). These methods have been compared to precipitation procedure, preconized at date by Arcol and SFBC. The intermethod comparison of calibrators and control sera occurred their using only with the reagents which they are supplied. The precision of the four homogeneous assays is acceptable (CV within-day <4,5 %, CV between-day <6,0 %). The new HDL-C assays are linear up to 2,50 mmol L −1. Bilirubin, haemoglobin and turbidity don't interfer. An intermethod comparison in 85 native serum samples yield correlation coefficients (precipitation procedure /homogeneous assays) between 0,954 and 0,963.

Factors associated with implementation of preventive care measures in patients with diabetes mellitus.

There is only limited information on the extent to which physicians' characteristics affect the level of care and implementation of guidelines in patients with diabetes mellitus. To identify physician characteristics associated with implementation of measures for preventive care in patients with diabetes mellitus and the distribution of implementation of these measures among them. A retrospective chart audit of 519 patients eligible for health maintenance organization insurance on December 31, 1994, representing patients with diabetes receiving care from 22 primary care physician-providers of a managed care medical group in suburban North Los Angeles, Calif, and seen by physicians between January 1993 and December 1994. A short retroactive questionnaire for participating physicians was also used. The outcome measures were (1) measurement of serum high-density lipoprotein cholesterol; (2) urinalysis for the detection of proteinuria; and (3) ophthalmology referral for dilated fundus examination. Over a period of 2 years 78% of the patients had a high-density lipoprotein cholesterol determination, 80% had a test for proteinuria, and 62% were referred to an ophthalmologist. After adjustment for patient pool differences, physicians who were perceived by the administration of the medical group as "fast," based on a blinded evaluation of their number of patient encounters per unit time, had an odds ratio of 0.60 (95% confidence interval [CI], 0.37-0.95; P=.03) to obtain a high-density lipoprotein cholesterol determination in their patients and an odds ratio of 0.53 (95% CI, 0.32-0.87; P=.01) to test their patients for proteinuria. In patients requiring insulin, of fast physicians, the odds ratio for a referral for ophthalmology screening was 0.25 (95% CI, 0.07-0.85; P= .03). Duration of time in practice of over 15 years and disagreement with practice guidelines were associated with better outcomes. There was no association between physician sex, internal medicine training, or number of patients with diabetes in the practice and the implementation of outcomes. There was a highly significant association between the implementation of an outcome and the implementation of the other 2, resulting in a nonhomogeneous distribution of health care delivery. Physicians' estimate of their rate of implementation of outcomes, as assessed by the questionnaires, overestimated their actual performance while being in proportion with the documented rates. Most physicians took responsibility for the nonimplementation, accepting that it was an oversight on their part as opposed to an encounter with patient resistance. Most physicians believe that the lack of implementation of the measures for preventive care in patients with diabetes mellitus is an oversight. The oversight is more prevalent in the practices of busy physicians. The result is a nonhomogeneous distribution of health care. Computer reminders might be the solution.