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Biomedical subjects

G Luc

Publications and source records attributed to G Luc.

At least 73 records · Page 4Linked to original sources

Relationship between low-density lipoprotein size and apolipoprotein A-I-containing particles: the ECTIM study.

It is now established that small dense low-density lipoproteins (LDLs) are more common among patients with coronary heart disease than among control individuals. Small LDL size is also associated with a high-risk profile, including increased levels of triglycerides and decreased high-density lipoprotein (HDL)-cholesterol. Furthermore, some human HDL particles contain both apolipoprotein (apo) A-I and apoA-II (LpA-I:A-II) while others contain apoA-I but are devoid of apoA-II (LpA-I). We have investigated the relationship between LDL size, measured by non-denaturing gradient-gel electrophoresis, and HDL parameters, particularly LpA-I and LpA-I:A-II levels, in healthy control subjects (n = 408). LDL size was positively and significantly correlated with HDL-cholesterol (r = 0.43), apoA-I (r = 0.32) and LpA-I (r = 0.29), whereas no correlation was observed with apoA-II and LpA-I:A-II. The determination of the mean apoA-I and LpA-I in the quintiles of LDL size distribution revealed a progressive increase in apoA-I and LpoA-I from the first quintile (small LDLs), 137 and 42 mg dL-1 respectively, to the fifth quintile (large LDLs), 161 and 54 mg dL-1 respectively. Conversely, no evolution of apoA-II and LpA-I:A-II was observed. Multivariate analysis showed that not only triglycerides, but also HDL-cholesterol, apoA-I and LpA-I, are determinants of LDL size, depending on the model used. Thus, part of the variation in size of LDLs is associated with the metabolism of HDL independently of that of triglycerides. Thus, a low concentration of LpA-I combined with the presence of small LDLs could contribute to the high-risk profile observed in subjects with small LDLs.

Adult↗

Postprandial lipaemia is associated with increased levels of apolipoprotein A-IV in the triacylglycerol-rich fraction and decreased levels in the denser plasma fractions.

Apolipoprotein (apo) A-IV is primarily associated with HDL or with the lipoprotein-free fraction of plasma, and in small amounts with chylomicrons and VLDL. The aim of the present study was to assess the effect of a fatty meal on the postprandial variation in plasma apo A-IV and on its distribution among lipoprotein fractions following absorption of fat. Twenty healthy male subjects participated in the study. After an overnight fast, subjects were given a fatty breakfast containing 1 g fat/kg body weight (% energy: fat 65, carbohydrate 20; protein 15). Blood samples were taken every hour during the next 10 h. Apo A-IV was measured by ELISA. Postprandial lipaemia was associated with a moderate, although significant, increase in the plasma levels of apo A-IV. Apo A-IV increased from the median baseline value of 0.15 g/l to 0.165 g/l (median +17%; P < 0.01) 5 h after fat ingestion. The postprandial peak of apo A-IV occurred 1 h after the triacylglycerol peak. There were no statistically significant correlations between baseline lipids, baseline apo A-IV and postprandial changes in apo A-IV levels, or between postprandial changes in lipids and apo A-IV at any time. To assess apo A-IV distribution among lipoproteins, plasma was fractionated by fast performance liquid chromatography at baseline and 3, 6 and 10 h postprandially. There was a substantial heterogeneity in the apo A-IV distribution among lipoproteins following the fatty meal. At 3 h after fat ingestion, apo A-IV levels increased in the triacyglycerol-rich lipoprotein (TRL) fraction and decreased in the denser plasma fraction. At 6 h after the fatty meal, apo A-IV was still present in the TRL but was decreased in the HDL fractions. The findings of the present study support the concept that apo A-IV particles transfer from the denser plasma fraction to TRL during postprandial lipaemia.

Adult↗

Awareness and control of hypertension and hypercholesterolaemia in France and Northern Ireland.

We assessed awareness and control of hypertension and hypercholesterolaemia in a cross-sectional study of 586 men from France and 189 from Northern Ireland, aged 35-55, without known coronary artery disease. Prevalence of hypertension was 28% in France and 31% in Northern Ireland (p < 0.42). In France, 70% of hypertensive subjects were aware of their status, vs. 58% in Northern Ireland (p < 0.10). Overall, 40% of subjects with a history of hypertension were untreated, and only 32% of the French and 12% of the Northern Irish subjects treated for hypertension (diet with/without drugs) were normotensive. The prevalence of hypercholesterolaemia was 46% in France and 48% in Northern Ireland (p < 0.62). In France, 59% of hypercholesterolaemic subjects were aware of their status, vs. only 17% in Northern Ireland (p < 0.0001). In both countries, half of those with a history of hypercholesterolaemia were untreated, and only 47% of the French and 43% of the Northern Irish patients treated for hypercholesterolaemia (diet with/without drugs) were controlled. While awareness of hypertension is comparable in France and Northern Ireland, awareness of hypercholesterolaemia is much lower in the latter. Control of hypertension and hypercholesterolaemia in both countries is poor and should be improved.

Adult↗

The Leu33/Pro polymorphism (PlA1/PlA2) of the glycoprotein IIIa (GPIIIa) receptor is not related to myocardial infarction in the ECTIM Study. Etude Cas-Temoins de l'Infarctus du Myocarde.

The GPIIb/IIIa receptor complex may contribute to acute coronary syndromes by mediating platelet aggregation. The Leu33/Pro polymorphism (PlA1/PlA2) of the GPIIIa has recently been shown to be associated with CHD in a small case-control study. We have investigated this polymorphism in a large multicenter study of patients with myocardial infarction and controls and found no difference in the distribution of allele and genotype frequencies between cases and controls.

Adult↗

Interstitial fluid apolipoprotein A-II: an association with the occurrence of myocardial infarction.

A sample of male patients aged 25-64 years, survivors of myocardial infarction (MI) taken from the Lille MONICA register, and age-matched control subjects from the general population were recruited in Lille and its surroundings in the North of France. Diabetics and subjects taking hypolipidemic drugs were excluded from the analysis, so that 73 MI and 144 control subjects were included. Lipids, apolipoprotein (apo) A-I, apo A-II, apo A-IV and apo B, and apo A-I-containing particles such as lipoproteins containing both apo A-I and apo A-II (LpA-I:A-II) and those containing apo A-I but not apo A-II (LpA-I) were measured in interstitial fluid by applying mild suction, and in plasma. Univariate analysis showed that plasma triglycerides, very low density lipoprotein (VLDL)-cholesterol and apo B were significantly higher, while high density lipoprotein (HDL)-cholesterol, apo A-I, LpA-I and LpA-I:A-II were lower in MI survivors compared to controls after adjustment for age, body mass index (BMI), alcohol and tobacco consumption. In interstitial fluid, cholesterol and apo A-II were higher in MI than in controls before adjustment for covariates. However, after adjustment, triglycerides became significant while cholesterol and apo A-II remained significantly higher in MI, at 43.8 and 7.5 mg/dl, respectively, than in control subjects, at 38.6 and 5.9 mg/dl, respectively. Taking into account only the plasma parameters, the multivariate analysis reveals that triglycerides and apo A-I appear to be independent factors indicative of the presence of a MI. When plasma and interstitial fluid parameters were taken together in the multivariate analysis, the measurement of apo A-II in interstitial fluid increased the level of prediction of MI over the information provided by the plasma parameters. These data raise the possibility that interstitial fluid apo A-II levels may be associated with the occurrence of MI.

Adult↗

Potential gene therapy for lecithin-cholesterol acyltransferase (LCAT)-deficient and hypoalphalipoproteinemic patients with adenovirus-mediated transfer of human LCAT gene.

BACKGROUND: Overexpression of human lecithin-cholesterol acyltransferase (LCAT) in transgenic mice results in an increase of the antiatherogenic HDLs. METHODS AND RESULTS: To investigate the potential use of LCAT for gene therapy, a recombinant adenovirus was constructed in which the human LCAT cDNA was expressed under the control of the human cytomegalovirus immediate/early promoter followed by a chimeric intron (AdCMV human LCAT). Human apolipoprotein (apo) A-I transgenic mice infected with AdCMV human LCAT by intravenous injection accumulated reactive LCAT in the plasma. LCAT activity was increased 201-fold in the plasma of mice infected with 1 x 10(6) pfu AdCMV human LCAT, from 45 +/- 2 to 9068 +/- 812 nmol.mL-1.h-1, in comparison with basal LCAT activity measured in control mice, 5 days after injection. Plasma HDL cholesterol levels rose from 117 +/- 12 to 797 +/- 48 mg/dL, and plasma human apo A-I concentrations increased from 247 +/- 14 to 616 +/- 17 mg/dL, in AdCMV human LCAT infected mice compared with control mice. HDL particles were larger and had a different electrophoretic mobility. Studies of cholesterol efflux by incubation of serum with cholesterol-loaded Fu5AH cells showed that serum from AdCMV human LCAT-infected mice promoted a significantly higher efflux than did that of the controls. CONCLUSIONS: These data establish the potential of this approach for treatment of subjects with LCAT gene defects as well as patients with low plasma levels of apo A-I and HDL cholesterol.

Adenoviridae↗

The Gln/Arg polymorphism of human paraoxonase (PON 192) is not related to myocardial infarction in the ECTIM Study.

Paraoxonase is a high-density-lipoprotein associated enzyme capable of hydrolyzing lipid peroxides, which has been suggested to contribute to atherosclerosis and coronary heart disease (CHD). We studied the Gln/Arg polymorphism affecting codon 192 of human paraoxonase (PON 192) to determine whether this polymorphism, which is associated with serum paraoxonase (PON) activity, represents a risk factor for myocardial infarction (MI). The PON 192 polymorphism was analysed in 642 male patients with myocardial infarction and 701 age-matched controls participating in the ECTIM Study (Etude Cas-Témoins de l'Infarctus du Myocarde). The frequency of the Gln allele was 0.69 in cases and 0.70 in controls (ns). The frequency of the PON 192/Arg allele in 405 MI patients who underwent coronary angiography was 0.295, 0.323 and 0.331, respectively in those with 1, 2 or 3 stenosed arteries (stenosis > 50%) (ns). The mean levels of several plasma lipids, lipoproteins and apolipoproteins were compared between the 3 PON genotypes and no difference was observed. The PON 192 polymorphism was unrelated to MI, the severity of coronary atherosclerosis and to plasma levels of several lipid variables.

Adult↗

Plasma homocyst(e)ine levels and graded risk for myocardial infarction: findings in two populations at contrasting risk for coronary heart disease.

Standardized mortality rates for coronary heart disease (CHD) in men are about 3-fold higher in Northern Ireland than in France. The differences could not be explained by the presence of conventional risk factors for atherosclerosis. We studied in subjects from these two countries, an additional risk factor, namely, concentration of plasma homocyst(e)ine which is frequently elevated in patients with CHD. We measured the plasma concentration of homocyst(e)ine in survivors of myocardial infarction (MI) and in control subjects from the Belfast, Strasbourg and Lille regions. Plasma homocyst(e)ine levels were higher in the Irish than in the French controls; subjects with MI had higher levels than controls. Results were compatible with global excess of risk for MI being graded across the distribution of plasma homocyst(e)ine concentrations, although the trends lost significance in Belfast after adjustment for other risk factors. The higher plasma homocyst(e)ine concentrations we observed in the Irish population could be the reason for the different CHD mortality rates. This epidemiological observation could prompt dietary and vitamin supplementation studies aimed at decreasing homocyst(e)ine levels as well as the incidence of arterial occlusive disease, under controlled conditions in high risk populations.

Adult↗

Association between the LPL-D9N mutation in the lipoprotein lipase gene and plasma lipid traits in myocardial infarction survivors from the ECTIM Study.

Using polymerase chain reaction (PCR) based techniques, we have identified individuals in the ECTIM study of myocardial infarction survivors (cases) and healthy matched controls who are carriers for a mutation of the gene for lipoprotein lipase (LPL) which alters amino acid 9 from aspartic acid to asparagine (LPL-D9N). The frequency of carriers in the cases from Belfast and France (3 separate centres) was 2.5 and 3.7%, respectively (mean 3.3%, 95% CI 1.9-4.7) and in the controls 2.0 and 2.9%, respectively (mean 2.7%, 95% CI 1.6-3.8%), but this difference was not statistically significant. In the cases, carriers of the allele for LPL-N9 had higher levels of several plasma lipid traits including total triglycerides (TG) (30%), very low density lipoprotein (VLDL) cholesterol (19%), apo E (24%), apo C-III (17%), lipoprotein particles (Lp) containing both apo E and apo B (LpE:B) (32%), and particles containing both apo C-III and apo B (LpCIII:B) (39%), and this effect was consistent in cases both from Belfast and from the French centres combined. By contrast, in the controls there were no differences in any lipid trait between carriers and non-carriers of the mutation that was consistent between the French centres and Belfast. There were no significant differences in the levels of any measured factor between cases and controls that could explain the different effect on plasma lipid traits associated with the mutation. However, compared to the non-carriers, in both cases and controls who carried the mutation, plasma TG concentrations were higher in those whose body mass index (BMI) was above the mean of the sample (26.0 kg/m2), with statistically significant interaction seen between BMI and genotype and levels of apo C-III, and lipoprotein particles containing both apo C-III and apo B (P < 0.02). The data suggest that carriers for the LPL-N9 mutation have a mild genetic predisposition to developing hyperlipidaemia and an atherogenic lipid profile, but that this requires the presence of other genetic or environmental factors for full expression, one of which appears to be increasing obesity.

Adult↗

Beta fibrinogen gene polymorphisms are associated with plasma fibrinogen and coronary artery disease in patients with myocardial infarction. The ECTIM Study. Etude Cas-Temoins sur l'Infarctus du Myocarde.

BACKGROUND: Polymorphisms of the beta fibrinogen gene have been shown to affect plasma fibrinogen levels and the risk of peripheral arterial disease. We now present the results of a detailed analysis of the beta fibrinogen gene in relation to plasma fibrinogen and to the severity of coronary artery disease (CAD) in patients with myocardial infarction (MI) in the ECTIM Study. METHODS AND RESULTS: Ten polymorphisms of the beta fibrinogen gene, including five new polymorphisms identified by single-strand conformation polymorphism analysis, and one polymorphism in the 3' flanking region of the alpha fibrinogen gene were investigated in 565 patients with MI and 668 control subjects. The polymorphisms were in tight linkage disequilibrium and the genotype frequencies were similar in patients with MI and control subjects. In the multivariate analysis, only two polymorphisms, beta Hae III (P < .0003) and beta-854 (P < .01), were independently associated with plasma fibrinogen. The significant association between beta fibrinogen polymorphisms and plasma fibrinogen was present in smokers but not in nonsmokers. In French MI patients, the number of coronary arteries with > 50% stenosis was estimated by angiography and used as a criterion for severity of CAD. Presence of the less frequent allele of the beta Bcl I (P < .0003) and of other polymorphisms was positively associated with the severity of CAD. CONCLUSIONS: Genetic variants of the beta fibrinogen gene are associated with an increased plasma level of fibrinogen, especially in smokers. The association with CAD appears to be the consequence of an increased risk of MI in subjects with severe CAD who carry the predisposing beta fibrinogen genotypes.

Adult↗

Factor VII Arg/Gln353 polymorphism determines factor VII coagulant activity in patients with myocardial infarction (MI) and control subjects in Belfast and in France but is not a strong indicator of MI risk in the ECTIM study.

This paper describes the relationship of factor VII coagulant activity (FVIIc), FVII Arg/Gln353 genotype and risk of myocardial infarction (MI) in the ECTIM (Etude Cas Témoin sur l'Infarctus du Myocarde) study, a multi-centre case-control study on MI. FVIIc was significantly higher in controls from all four centres: Belfast, Lille, Strasbourg and Toulouse, perhaps because elevated FVIIc may predispose to fatal rather than non-fatal MI. Major influences on FVIIc were FVII Arg/Gln353 genotype, triglyceride and cholesterol levels. There was no significant effect of genotype on MI risk however there was a non-significant trend towards increased MI risk in FVII Arg353 homozygotes. Confirming previous observations, FVIIc was highest in FVII Arg353 homozygotes, intermediate in heterozygotes and lowest in FVII Gln353 homozygotes (except Toulouse cases) these differences being highly statistically significant (except Strasbourg cases P = 0.1). In Belfast, consistent with previous findings, there was significant interaction between FVII Arg/Gln353 genotype and triglyceride level in determining FVIIc, whilst this was absent in the French centres. In conclusion, FVII Arg/Gln353 genotype strongly determines FVIIc although neither factor has a strong impact on MI risk in the ECTIM study.

Adult↗

DNA polymorphisms in linkage disequilibrium at the 3' end of the human APO AII gene: relationships with lipids, apolipoproteins and coronary heart disease.

Two investigations were undertaken to analyze the 3' region of the apolipoprotein AII (Apo AII) gene in patients with myocardial infarction (MI) and controls. Previous studies have suggested that a MspI polymorphism in this gene may be associated with hypertriglyceridaemia, high levels of HDL cholesterol and Apo AII. To verify this hypothesis, the distribution of MspI genotypes and their possible associations with several plasma lipid variables were studied in 882 subjects (411 cases with MI and 471 controls) from the ECTIM study. There were no differences in genotype and allele frequencies between cases and controls, and no differences in lipid variable levels in controls carrying the less frequent MspI allele vs other controls. Using single-strand conformation polymorphism (SSCP) analysis, we detected a new polymorphism which caused by a C-to-T transition located in the third intron near the splice junction site (acceptor). This polymorphism modifies a Bst N1 restriction site. The ECTIM population was screened for this new marker, and no significant associations with MI and plasma lipid levels were found. Our results suggest that these two variants located in the coding region of the Apo AII gene are unlikely to contribute significantly to the level of plasma lipid variables and the risk of coronary heart disease (CHD) in the European population.

Adult↗

Polymorphisms of the transforming growth factor-beta 1 gene in relation to myocardial infarction and blood pressure. The Etude Cas-Témoin de l'Infarctus du Myocarde (ECTIM) Study.

Transforming growth factor-beta 1 (TGF-beta 1) plays an important role in the modulation of cellular growth and differentiation and the production and degradation of the extracellular matrix. A number of experimental results suggest that TGF-beta 1 may be involved in cardiovascular physiopathology. In the present study, we assessed whether the TGF-beta 1 gene is a candidate gene for coronary heart disease or hypertension. We screened the coding region and 2181 bp upstream of the TGF-beta gene for polymorphisms and identified seven polymorphisms: 3 in the upstream region of the gene at positions -988, -800, and -509 from the first transcribed nucleotide; 1 in a nontranslated region at position +72; 2 in the signal peptide sequence Leu10-->Pro, Arg25-->Pro; and 1 in the region of the gene coding for the precursor part of the protein not present in the active form, Thr263-->Ile. We analyzed these TGF-beta 1 polymorphisms in 563 patients with myocardial infarction and 629 control subjects from four regions in Northern Ireland and France. The Pro25 allele was more frequent in patients than in control subjects in Belfast (P < .01) and Strasbourg (P < .05). The TGF-beta 1 polymorphisms were not associated with the degree of angiographically assessed coronary artery disease in patients. The presence of a Pro25 allele was associated with a lower systolic pressure in the four control groups (P < .002), and a history of hypertension was significantly less frequent in homozygotes or heterozygotes for Pro25 than in hormozygotes for Arg25 (odds ratio, 0.43, 95% confidence interval, 0.19 to 0.92; P < .03). Since the Pro25 allele was associated with an increased risk of myocardial infarction and a reduced risk of hypertension, we favor a cautious interpretation of these apparently inconsistent results. Other studies will need to verify whether these associations are real.

Adult↗

Rapid quantification of alpha-tocopherol in plasma and low- and high-density lipoproteins.

We have developed two methods for measuring the alpha-tocopherol content in plasma and lipoproteins (LDL and HDL). In procedure 1, plasma or lipoproteins are deproteinized with ethanol containing delta-tocopherol as internal standard and then extracted with hexane or ethyl acetate. The organic layer is removed and evaporated, and the residue is redissolved in methanol and injected into a reversed-phase HPLC. In procedure 2, plasma or lipoproteins are diluted in a methanol and ethanol mixture containing the same internal standard. The solution is vortex-mixed, centrifuged, and directly injected into the column. The tocopherols are eluted with an isocratic methanol mobile phase at a flow rate of 1 mL/min and detected by fluorescence (lambda(exc)= 295 nm, lambda(em)= 330nm). Recoveries are approximately 100% in both cases. Between-run CVs were 8.39% for procedure 1 and 6.55% for procedure 2. Small sample requirement, simplicity of sample preparation, short assay time, and good reproducibility make procedure 2 ideal for clinical or research use. This method was applied to determination of alpha-tocopherol in plasma of patients whose diet was supplemented with alpha-tocopherol and in LDL and HDL.

Chromatography, High Pressure Liquid↗

Apolipoproteins C-III and E in apoB- and non-apoB-containing lipoproteins in two populations at contrasting risk for myocardial infarction: the ECTIM study. Etude Cas Témoins sur 'Infarctus du Myocarde.

Apolipoprotein (apo) C-III and apoE are components of two major classes of plasma lipoproteins, i.e., apoB- and non-apoB-containing lipoproteins. To analyze the relationship between the distribution of apoC-III and apoE among lipoproteins and coronary heart disease, we compared the distribution of these two apolipoproteins in survivors of myocardial infarction (MI) and control subjects, within and between populations at contrasting risk for MI. ApoC-III and apoE concentrations were determined in plasma devoid of apoB-containing lipoproteins by immunoprecipitation using a specific anti-apoB antiserum. These assays referred to apoC-III-Lp non-B and apoE-Lp non-B, respectively. By examining the difference with total plasma apoC-III and apoE levels, we calculated apoC-III and apoE in apoB-containing lipoproteins (apoCIII-LpB and apoE-LpB, respectively). These determinations were performed in control subjects and in survivors of MI, all males aged 25 to 64 years. They were recruited in Northern Ireland and France, countries characterized by a large difference in the incidence of coronary heart disease. In univariate analysis, apoCIII-LpB appeared significantly higher and the apoC-III ratio (apoC-III-Lp non-B/apoC-III-LpB) significantly lower in MI survivors than in control subjects in both countries. ApoE-LpB was higher in MI survivors than in control subjects in Northern Ireland but not in France. The two French and Irish control populations differed for apoC-ILL-Lp non-B, apoC-III ratio, and apoE ratio, which were higher in France than in Northern Ireland, and for apoC-III-LpB, apoE, and apoE-LpB, which were lower. Multivariate analysis showed that no parameter involving apoC-III and apoE was more discriminatory than HDL-cholesterol, cholesterol, and triglycerides or apoA-I, apoB, and triglycerides between controls and MI subjects. In contrast, the apoC-III ratio was a better discriminatory parameter between the two control populations than the listed parameters. The differences between the two control populations are of particular interest because they are not biased by the presence of disease or the large difference of the incidence in coronary heart disease between the two countries. It is suggested that the distribution of apoC-III among lipoproteins may play a role in the different susceptibility of the two populations to the atherogenic process.

Adult↗

Effects of gender and menopausal status on plasma lipoprotein subspecies and particle sizes.

The risk of coronary heart disease (CHD) is lower in women than in men, but increases in women after menopause. Some of the gender, age, and menopausal-related differences in CHD risk may relate to differences in lipoprotein subspecies. We therefore examined these subspecies in three groups of healthy subjects: premenopausal women (W, n = 72, mean age 41.2 +/- 6.5), postmenopausal women (PMW, n = 74, 55.8 +/- 7.4), and men (M, n = 139, 48.8 +/- 10.7). We measured plasma levels of lipids, lipoprotein cholesterol, apolipoproteins A-I, A-IV, B, C-III, and E, and lipoprotein subspecies Lp A-I, Lp A-I:A-II, Lp B, Lp B:C-III, and Lp B:E, as well as LDL and HDL particle sizes. Our data indicate that women have significantly higher values of HDL-C, apoA-I, apoE, and Lp A-I; larger LDL and HDL particle sizes; and lower values of triglyceride, apoB, and Lp B:C-III particles than men, with no difference in Lp A-I:A-II. Postmenopausal status was associated with significantly higher values of total cholesterol, triglyceride, VLDL-C, and LDL-C; increased levels of apoB, C-III, and E; elevated values of Lp B, Lp B:C-III, and Lp B:E; and lower levels of HDL-C along with smaller HDL particle size. Moreover, we noted a strong correlation between LDL and HDL particle size. Our data are consistent with the concepts that male gender confers decreases in HDL subspecies due to lower Lp A-I levels; while postmenopausal status results in higher levels of all apoB-containing lipoproteins (Lp B, Lp B:C-III, and Lp B:E). The lipoprotein alterations associated with male gender and postmenopausal status would be expected to increase CHD risk.

Adult↗