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J C Fruchart

Publications and source records attributed to J C Fruchart.

At least 235 records · Page 13Linked to original sources

Lipoprotein lipase gene polymorphisms: associations with myocardial infarction and lipoprotein levels, the ECTIM study. Etude Cas Témoin sur l'Infarctus du Myocarde.

Several lipoprotein lipase (LPL) gene polymorphisms have been found associated with fasting lipid levels, but their impact on coronary heart disease (CHD) is less clearly established. We investigated associations of LPL polymorphisms (HindIII, PvuII, Ser447-->Ter) and the newly described mutation Asn291-->Ser with the risk of myocardial infarction (MI), severity of atherosclerosis, and fasting plasma lipoprotein concentrations in the ECTIM study (614 patients and 733 controls). The Ter447 allele had a lowering effect on triglycerides (P < 0.01), VLDL-cholesterol (P < 0.05), apoC-III (P < 0.001), LpE:B (P < 0.01), and LpCIII:B (P < 0.05), and a raising effect on apoA-I levels (P < 0.05). The H- allele of the HindIII polymorphism was associated with lower apoC-III (P < 0.01) and higher HDL-cholesterol (P < 0.05) levels. The PvuII and Asn291-->Ser polymorphisms did not exhibit any significant association with the biochemical traits examined. The HindIII genotype distributions differed between cases and controls, the odds ratios for MI associated with H+H+ and H+H- genotypes being 2.05 (P < 0.01) and 1.74 (P < 0.05) by reference to H-H-. The lack of association between Ser447-->Ter and MI suggested that this mutation was unlikely to be the cause of the association found with HindIII. In some cases, the severity of atherosclerosis assessed by coronarography increased with the presence of P+ allele (coronary scores: 1.41, 1.57, and 1.64 in P-P-, P-P+, and P+P+ individuals respectively, P < 0.05). A similar trend on the coronary score was observed with the presence of the Asn291-->Ser mutation (1.58 vs. 1.90, P = 0.06). Our results suggest that the LPL gene is involved in the determination of lipoprotein profiles, the predisposition to CHD, and the severity of atherosclerosis.

Adult↗

Fatty acid composition of brain capillary endothelial cells: effect of the coculture with astrocytes.

We have investigated the fatty acid composition of brain capillary endothelial cells cultured alone or in coculture with astrocytes, using an in vitro model in which endothelial cells and astrocytes were grown from one part of a filter to another. We found that the fatty acid composition of the cocultured cerebral endothelial cells was markedly different from that of non-cocultivated endothelial cells. The most striking difference was the increase of arachidonic acid (20:4n-6) at the expense of its precursor, linoleic acid (18:2n-6). Similar modifications were found for the n-3 family of fatty acids with an increase of docosahexaenoic acid (22:6n-3) at the expense of its precursors, but the differences were less than within the n-6 fatty acids. These changes induced by the coculture were observed only in endothelial cell phospholipids, especially the phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine classes, but were not detected in phosphatidylinositols and in other lipid classes. Only the composition of the n-3 series fatty acids was altered in another capillary endothelial cell type (from adrenal cortex) cocultured with astrocytes under the same conditions. The fatty acid changes observed might be biologically relevant as they tended to make the fatty acid composition of the brain capillary endothelial cells more closely resemble that of brain microvessels.

Adrenal Cortex↗

[The important role of apolipoprotein C-III in lipoprotein metabolism].

Apolipoprotein C-III (apo C-III) is present in the plasma in apo B containing lipoprotein (apo C-III-LpB) and in non apo B containing lipoprotein (apo C-III-Lp non B). Apo C-III inhibits the lipolysis of triglyceride riche particles and the apo B containing lipoprotein binding to the LDL receptor. A clinical study in myocardial infarction survivors (ECTIM study) shows that apo C-III-LpB is a good marker of atherogenesis. Hypolipidemic drugs as fenofibrate and Maxepa decrease the apo C-III-LpB particles. These studies demonstrate that apo C-III presents an important role in apo B containing lipoprotein particles metabolism and atherogenesis. Furthermore apo C-III levels may be reduced by hypolipidemic drugs.

Animals↗

Negative regulation of the human apolipoprotein A-I promoter by fibrates can be attenuated by the interaction of the peroxisome proliferator-activated receptor with its response element.

Fibrates have been reported to modulate plasma high density lipoprotein cholesterol and apolipoprotein (apo) A-I concentrations. Therefore, the molecular mechanisms underlying the regulation of human apoA-I gene expression by fibrates was investigated. Fenofibrate reduced the expression of a reporter gene driven by the DNA sequences between -192 and +91 (BC-P-chloramphenicol acetyltransferase; CAT) relative to the apoA-I gene transcription start site approximately 3-fold. The sequences involved in the down-regulation of apoA-I gene transcription by fenofibrate were localized between -41 and +91 (P-CAT) relative to the transcription start site. The reduction of the expression of BC-P-CAT was dose-dependent and maximal at 500 microM (20 +/- 7%). Different peroxisome proliferators showed different levels of repression varying from 39 +/- 4% for fenofibrate, 43 +/- 5% for tetradecylthioacetic acid, 48 +/- 4% for bezafibrate, 54 +/- 2% for 5,8,11,14-eicotetraynoic acid, 76 +/- 2% for ciprofibrate, whereas Wy 14643 only marginally inhibited the expression of BC-P-CAT. By contrast, inclusion of sequences between -256 and -192 (ABC-P-CAT) attenuated the repression by fenofibrate. Furthermore, the apoA-IA site (-214 to -192; Awt-P-CAT) could counteract the repression of P-CAT by fenofibrate in the presence of cotransfected mPPAR alpha (peroxisome proliferator-activated receptor). In addition, the acyl-CoA oxidase-peroxisome proliferator response element (PPRE) could substitute the wild-type A-site in blocking the fenofibrate-induced reduction of the apoA-I promoter by mPPAR alpha. The protective effect of PPAR on fenofibrate induced inhibition of apoA-I expression was abolished after mutation of the direct repeat in the A site (Am-P-CAT). Consistent with these functional data only the wild-type, but not the mutated A site bound PPAR/retinoic X receptor heterodimers in gel shift assays. These data suggest that certain peroxisome proliferators can reduce the expression of the apoA-I promoter in a PPAR-independent fashion, through modulation of factors interacting with sequences localized between -41 and +91 of the apoA-I gene transcription initiation site. This inhibitory effect can be overcome when PPAR interacts with a functional PPRE, such as the apoA-I A site or the acyl-CoA oxidase-PPRE.

Animals↗

Identification of specific amphipathic alpha-helical sequence of human apolipoprotein A-IV involved in lecithin:cholesterol acyltransferase activation.

To investigate the structure-function relationship of human apolipoprotein A-IV (apoA-IV), several deletion mutants of this protein were constructed by sequentially removing pairs of 22-residue repeats, potentially having an amphipathic alpha-helical conformation. The mutants, produced as recombinant poly-histidine-tagged apolipoproteins (t-apo) in Escherichia coli, assembled with phosphatidylcholine (i.e. dimyristoylphosphatidylcholine, palmitoyloleoylphosphatidylcholine, or egg lecithin) as did native apoA-IV. Lecithin:cholesterol acyltransferase (LCAT) cofactor function, measured as cholesterol esterification occurring when t-apo-phosphatidylcholine-cholesterol complexes were incubated with purified enzyme, decreased significantly when pairs of repeats between residues 117 and 248 were deleted and most markedly when residues 117-160 were deleted. LCAT cofactor activity decreased by 90 and 75%, respectively, when egg lecithin or palmitoyloleoylphosphatidylcholine was used to form the particles with the delta aa 117-160 mutant. Thus, on the basis of deletion scanning of t-apo, residues 117-160 seem to be involved in the LCAT cofactor function of apoA-IV.

Amino Acid Sequence↗

[New methods in lipid research].

Arteriosclerosis is an insidious multifactorial disease. Treatment relies mainly on prevention. Abnormal lipoproteins are major risk factors leading to arteriosclerosis in general and specifically to coronary artery disease. Lipid-related risk factors should be evaluated in a stepwise process. The first step involves screening for raised fasting levels of blood cholesterol and triglycerides. Depending on the initial results, further classification may be required based on the blood levels of high density lipoproteins (HDL). Concentration of low density lipoproteins (LDL) can be calculated from blood cholesterol, triglycerides, and HDL levels. These two parameters, HDL-cholesterol and LDL-cholesterol are essential to evaluate the risk of coronary artery disease. Currently, it is difficult to interpret the results of apolipoprotein AI and B assays since it has not been proved that the evaluation of coronary risk, as defined from HDL-cholesterol and LDL-cholesterol levels, is modified with the incorporation of apolipoprotein values. In addition, assay methods have not been standardized, hindering the use of apolipoprotein levels in evaluating risk. The basic assay methods provide a wide range of results, making it possible to measure subfractions of lipoproteins which would play a protective preventive role against arteriosclerosis. Lipoprotein A1 (LpAI) is protective while Lp(a) is an atherogenic lipoprotein. Both LpAI and Lp(a) are now routine laboratory tests and provide essential information for helping the clinician define the risk of arteriosclerosis and thus to make therapeutic decisions. In the future, genetic markers will undoubtedly provide better means of appreciating the pathophysiological mechanisms of arteriosclerosis and thus the risk of arterial lesions.

Aged↗

A screening method for abnormally high lipoprotein(a) concentrations by agarose lipoprotein electrophoresis.

A routine electrophoretic method detecting plasma lipoprotein(a) (Lp(a)) is described. Plasma lipoproteins were electrophoresed using an agarose gel film containing cations which retard migration of beta-, prebeta- and alpha-bands. When present, the Lp(a)-band was detected between prebeta- and alpha-bands. This extra-band lipoprotein has been demonstrated to be Lp(a), by an immunofixation technique using anti-Lp(a) antibodies. This original procedure allows a distinct separation of Lp(a) from prebeta even after samples have been stored at 4 degrees C for several days, or in cases of hyperlipemic samples with increased prebeta lipoproteins. The reliability of this detection test has been tested in comparison with an Lp(a) electroimmunoassay. Both these techniques have been performed on 719 randomly selected subjects. With electrophoresis, the Lp(a)-positive subjects accounted for 34.2% of the subjects and although this method does not distinguish between different levels of positivity (depending on the sample), the presence of Lp(a)-band was always perceptible at concentrations that belong to the upper 15th percentile of values as determined by electroimmunodiffusion; inversely, all Lp(a)-positive plasma was measurable. In consequence, since it is reliable and relatively inexpensive, this detection test on modified agarose gel appears very useful for revealing the presence of abnormally high values of Lp(a) in populations.

Adolescent↗

Cloning and sequencing of cDNAs encoding the human hepatocyte nuclear factor 4 indicate the presence of two isoforms in human liver.

Hepatocyte nuclear factor 4 (HNF-4) is a key transcription factor involved in the specific expression of many genes in liver and intestine. Sequences of cDNAs coding for HNF-4 have been established in rat and Drosophila melanogaster. Rat HNF-4 exhibits two isoforms which probably result from differential splicing. We have isolated HNF-4 cDNAs from an adult human cDNA library. Sequence analysis revealed that two HNF-4 isoforms are also present in human liver. The complete sequence of the longest human isoform has been established and compared to the rat HNF-4 amino-acid sequences.

Adult↗

Transcription of the human apolipoprotein A-II is down-regulated by the first intron of its gene.

Several reports indicate that apoA-II, the second most abundant HDL protein, plays a crucial role in modulating the anti-atherogenic behavior of HDL. Regulatory elements located 5' to the human apoA-II promoter have been previously described. In this paper we report that the first intron of the human apoA-II gene down-regulates its own promoter and the ubiquitous thymidine kinase promoter both in HepG2 and Caco-2 cells. The intron contains three sequences which bind nuclear proteins, thus demonstrating the presence of regulatory elements downstream of the transcription start site of the apoA-II gene.

Apolipoprotein A-II↗

Fluvastatin reduces levels of plasma apo B-containing particles and increases those of LpA-I. European Fluvastatin Study Group.

Epidemiologic studies have demonstrated an association between apolipoprotein (apo) B-containing particles (lipoprotein [Lp] E:B; LpC-III:B) and an inverse association between LpA-I and the risk of coronary artery disease (CAD). The effect of 6 weeks of treatment with fluvastatin (20 and 40 mg/day in the evening), a novel competitive inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, on lipoparticle levels was studied in 423 patients with hypercholesterolemia after 14 weeks of standard dietary therapy. The combined data of the European double-blind controlled studies were used for the analysis. Two independent groups of hypercholesterolemic patients receiving fluvastatin (20 and 40 mg every evening) for 6 weeks were compared with a placebo group. For inclusion, patients had to fulfill the following criteria: plasma low-density lipoprotein (LDL) cholesterol levels > 160 mg/dL and premature CAD and/or two associated risk factors; LDL cholesterol > 190 mg/dL and no CAD; triglycerides < 300 mg/dL. All measurements were performed at the Pasteur Institute Central Laboratory, LpE:B and LpC-III:B were measured by double-site ELISA. Lipoprotein A-I and LpA-I:A-II were determined by differential electroimmunodiffusion. Treatment with 20 and 40 mg of fluvastatin was associated with reductions in plasma apo B (median change: -19.3% and -22.8%, respectively; p < 0.001), LpE:B (-12.5% and -22.6%, respectively; p < 0.001), and LpC-III:B (-3.6% and -36.8%, respectively; p < 0.001) particles compared with placebo. Significant increases in plasma apo A-I (1.7% and 4.8%, respectively; p < 0.001) and antiatherogenic LpA-I (2.3% and 6.9%, respectively; p < 0.001) were also observed. Levels of LpA-I:A-II were not affected by fluvastatin treatment. In conclusion, 6-week treatment with fluvastatin is associated with beneficial antiatherogenic changes in lipoparticle profiles in hypercholesterolemic patients.

Analysis of Variance↗

Structural domain of apolipoprotein A-I involved in its interaction with cells.

Apolipoprotein A-I (apo A-I) is the major protein constituent of high-density lipoprotein (HDL), the lipoprotein fraction which mediates the reverse cholesterol transport. This apolipoprotein plays an important role in the binding of HDL to cells and participates in the efflux of cellular cholesterol. We have recently compared six different genetic variants of apo A-I and found that the apo A-I (Pro 165-->Arg) mutant is defective in promoting cellular cholesterol efflux from murine adipocytes and peritoneal macrophages and we have proposed that this region of apo A-I may be involved in their interaction with cells. To confirm this hypothesis, four monoclonal antibodies (mAbs) specific for apo A-I were used to study the inhibition of the interaction of palmitoyloleoylphosphatidylcholine (POPC): apoA-I complexes with HeLa cells and adipocytes. Among these antibodies, the apo A-I epitope recognized by the A44 mAb lies in the COOH terminal region (amino acid residues 149-186) including the proposed region. The antibodies A05, and A03 react with residues 25-82, 135-140, respectively and the A11 mAb corresponds to a discontinuous epitope at residues 99-105 and 126-132. Our results show clearly that the A44 and A05 mAbs reduce both the binding to HeLa cells and the cholesterol efflux from adipocytes. The inhibition of POPC: apoA-I complexes binding to both cell types is more strictly observed with the Fab fragments of monoclonal antibodies A44 and A05. Partial cotitration curves of these mAbs in a solid phase assay (RIA), indicated partial competition between these two antibodies. We propose a structural model for the POPC: apoA-I complexes where the N-terminal domain of one apo A-I molecule is in close spatial relationship with the C-terminal domain of the adjacent apo A-I molecule. We therefore suggest that the domain around amino acid 165 of apo A-I and which is recognized by mAb A44 (149-186) forms or contains some specific regions which mediate selectively the interaction with the binding site of cells and is involved in the efflux of cellular cholesterol.

Adipocytes↗

Lipoproteins containing apolipoprotein A-IV: composition and relation to cholesterol esterification.

In order to investigate the relationship of lipid and apolipoprotein composition to cholesterol esterification in lipoproteins containing apolipoprotein (apo) A-IV, apo A-containing lipoprotein particles were isolated from fresh human plasma using a system of sequential immunoaffinity chromatography. Plasma was first depleted of apo B- and apo E-containing lipoproteins. Four major subpopulations of apo A-containing lipoprotein particles were separated: Lp A-I, Lp A-I: A-II, Lp A-IV and Lp A-I: A-IV: A-II. Lp A-IV and Lp A-I: A-IV: A-II contained less total lipid, less cholesterol and more triacylglycerol than Lp A-I and Lp A-I: A-II. Lp A-IV and Lp A-I: A-IV: A-II contained more sphingomyelin and less phosphatidylcholine than Lp A-I and Lp A-I: A-II and were richer in (16:0 + 18:0) saturated fatty acids. Among these isolated lipoprotein particles, Lp A-IV contained the highest lecithin: cholesterol acyltransferase (LCAT) activity per micrograms of protein. Cholesterol esterification rates were 2.6 +/- 0.5, 5.3 +/- 0.4 and 0.8 +/- 0.2 mumol of cholesterol per hour per mg of lipoproteins for Lp A-IV, Lp A-I and Lp A-I: A-II, respectively. The apolipoprotein and lipid composition and LCAT activity of Lp A-IV suggest that this lipoprotein may be a source of cholesterol esterification in plasma.

Adult↗

Fenofibric acid modulates the human apolipoprotein A-IV gene expression in HepG2 cells.

The influence of the hypolipidemic drug, fenofibric acid, on the regulation of apolipoprotein A-IV (apoA-IV) gene expression was investigated in two human cell lines, HepG2 and Caco-2. As shown in the present report, fenofibric acid induces a strong dose-dependent increase of the apoA-IV mRNA level in HepG2 cells, while other apolipoproteins mRNA levels are only slightly modified. In Caco-2 cells, no modification is observed, except for a 2-fold increase of the apoE mRNA level. The increase of the apoA-IV mRNA level could be correlated with a clear enhancement of DNase I hypersensitive sites in the 5' flanking region of the gene in nuclei of HepG2 cells treated with fenofibric acid. Thus, fenofibric acid may act by facilitating the interaction of nuclear regulatory proteins with the DNA in the control regions of the apoA-IV gene.

Apolipoproteins↗

Sources of variability of human plasma apolipoprotein A-IV levels and relationships with lipid metabolism.

Plasma apolipoprotein (apo) A-IV concentration was determined by immunoelectrophoretic assay (EIA) in 119 nuclear families. No significant effect of concomitants such as age, weight, height, body mass index, tobacco, and alcohol consumption was observed on apo A-IV levels in men and in boys. In women, contraceptive use and hormonal status affected apo A-IV levels. In girls, only age influenced the quantitative phenotype. After adjusting by specific concomitants significant correlations were observed between apo A-IV levels and triglycerides, apolipoprotein A-I and apo B levels, suggesting a role of apolipoprotein A-IV in the hepatic lipid metabolism. Intrafamilial correlations were estimated to investigate the plausibility of a common family factor. The results obtained in this study showed a significant correlation between family members with the exception of mother-daughter pairs. Using a variance components model, the contribution of genetic and environmental factors was then investigated. Different statistical models were used and two major hypotheses were statistically acceptable: the first hypothesis supports that shared and specific environmental factors explain 35 and 65%, respectively, of the total adjusted plasma apo A-IV variation. The fraction of apo A-IV variability attributable to genetic factors was null. The second hypothesis supports that the fraction of variability attributable to apo A-IV genetic variation is 67% and the common spouse environmental factors are responsible for 33% of the total variability and no specific environmental effect was found. Among the two hypotheses, taking account of the metabolism function, we support the first one without excluding gene-environment interactions which could mask the genetic influence.

Adult↗

Fluvastatin efficacy and tolerability in comparison and in combination with cholestyramine.

The aim of this study was to investigate the new synthetic HMG-CoA reductase inhibitor, fluvastatin, for efficacy, safety and tolerability in comparison to cholestyramine. One hundred fifty one primary hypercholesterolaemic patients participated in this double-blind, parallel-group, randomized study. During the first 12 weeks of the study, fluvastatin (20 mg and 40 mg daily) was compared with cholestyramine (16 g per day). In the subsequent, 6-week part of the study, the comparative efficacy, safety and tolerability of 20 mg fluvastatin, combined with cholestyramine (4 g, 8 g, or 16 g) were assessed. Fluvastatin (40 mg) reduced LDL cholesterol by 28.0%, triglycerides by 10.5% and increased HDL cholesterol by 3.7%. Cholestyramine (16 g) reduced LDL cholesterol by 35.0%, but raised triglycerides and HDL cholesterol by 12.3% (p < 0.01) and 3.7% respectively. The combination of fluvastatin 20 mg and cholestyramine (4 g, 8 g and 16 g) induced the following reductions in LDL cholesterol: 30.4%, 35.6% and 46.6% respectively. There was no significant change in triglycerides in either group although HDL cholesterol was raised by 4.9%, 8.3% and 7.2% respectively. One patient treated with fluvastatin and two treated with cholestyramine were withdrawn from the study due to elevation of liver transaminases. The most frequent subjective adverse effects in both treatment groups were mild, transient gastrointestinal complaints. Thus, fluvastatin was effective as a lipid-lowering agent; the effect was further enhanced when fluvastatin was combined with cholestyramine.

Anticholesteremic Agents↗

Apolipoprotein A-I-containing particles and reverse cholesterol transport: evidence for connection between cholesterol efflux and atherosclerosis risk.

It is now clearly established that apo A-I-containing lipoproteins exist as two major families, those containing apo A-I and apo A-II (LpA-I:A-II) and those containing apo A-I but free of apo A-II (LpA-I). Metabolic studies utilizing radiolabeled lipoprotein particles suggested that there is a kinetic difference between LpA-I and LpA-I:A-II family and support the concept that there may be important functional differences between the lipoprotein particles present within HDL. Of considerable significance was the finding that proteins stimulating reverse cholesterol transport (lecithin:cholesterol acyltransferase (LCAT), cholesteryl ester transfer protein (CETP)) are mainly present in LpA-I and not in LpA-I:A-II family. Cholesterol efflux mediated by A-I-containing particles has been studied in different cells. Long term exposure to LpA-I family promoted cholesterol efflux whereas less efflux was observed in the presence of LpA-I:A-II family. The fact that LpA-I:A-II family can inhibit the LpA-I promoted cholesterol efflux strongly supports the role of apo A-II as an antagonist in the production of cholesterol efflux. These results which emphasize that LpA-I and LpA-I:A-II families behave as distinct entities have been confirmed in other studies showing that they have different clinical significance. The results in mice transgenic for apo A-I indicate that overexpression of apo A-I induces more cholesterol efflux and protects C57BL/6 mice from atherosclerosis. Increased expression of apo A-II in mice appears to decrease cholesterol efflux and to promote rather than retard aortic fatty streak development.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Evidence of non-deficient low-density lipoprotein receptor patients in a pool of subjects with clinical familial hypercholesterolemia profile.

For this study, we selected 41 adult patients with the classic clinical diagnosis of heterozygous familial hypercholesterolemia (FH), which is characterized by a low-density lipoprotein (LDL) cholesterol level above the 95th percentile, xanthomas, and/or personal or familial cardiovascular history. We used an indirect immunocytofluorimetric assay to classify these 41 subjects according to LDL receptor function on lymphocytes. We found that LDL receptor activity was normal in nine patients. A large study of plasma lipid, lipoprotein, and apolipoprotein levels found no significant difference between patients with and without LDL receptor defect. Familial defective apolipoprotein (apo) B-100 (FDB) and LDL-binding defects were not found in the nine patients without LDL receptor defect. These results suggest that other defects in the regulation of lipoprotein metabolism are capable of giving rise to a clinical and biochemical disorder indistinguishable from classic FH.

Adult↗

[Vitamin E, antioxidants and atherosclerosis].

Atherosclerosis is a process in which lipid and factors are mixed. When LDL are oxydized, they are catabolized by the macrophage's pathway, leading to foam cells which constitute the fatty streak, the earliest lesion in atherogenesis, and they have cytotoxic, chemotactic effects. Many protective devices against free radicals and oxydation mechanisms exist, particularly antioxydant vitamins and other natural dietary antioxydants. After a brief recall of their mechanisms, epidemiological, experimental and clinical data are reviewed. To day it seems necessary to take into consideration these factors in prevention and therapeutic of atherosclerosis and dylipidaemia. Many inquiries keep going, particularly about susceptible of LDL to oxydation. One is waiting for intervention surveys in order to conclude about nutritional and medical treatments.

Antioxidants↗