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P Cardot

Publications and source records attributed to P Cardot.

At least 37 records · Page 2Linked to original sources
PubMed1991

Promoter elements and factors required for hepatic transcription of the human ApoA-II gene.

The apolipoprotein A-II (apoA-II) gene regulatory region -911 to +29 strongly promotes the transcription of the promotorless chloramphenicol acetyltransferase (CAT) gene in cells of hepatic (HepG2) and intestinal (CaCo2) origin but not in HeLa cells. Deletion of nucleotides -911 to -860 decreased the hepatic and intestinal transcription to 7% and 18% of control, respectively. Further progressive deletions extending to nucleotides -614, -440, -230, and -80 abolished both hepatic and intestinal transcription, indicating that the distal promoter region -911 to -614 contains regulatory elements that are essential for intestinal and hepatic transcription. An internal deletion of the -614 to -230 region decreased hepatic transcription 60% while it increased intestinal transcription 140% of control indicating that the elements which control hepatic and intestinal transcription of the apoA-II gene may be different within this regulatory region. DNase I footprinting analysis with rat liver nuclear extracts identified 14 protected regions: A, -40 to -33; B, -65 to -42; C, -126 to -110; D, -276 to -255; E, -377 to -364; F, -404 to -384; G, -468 to -455; H, -573 to -554; I, -706 to -680; J, -734 to -716; K, -760 to -743; L, -803 to -773; M, -853 to -829, and N, -903 to -879, as the DNA binding sites for nuclear factors. Five of the regions (B, C, G, H, and K) bind to heat-stable factors. DNA binding gel electrophoretic assays indicated that region N (-903 to -879), which is essential for efficient transcription, binds predominantly a nuclear activity designated AIIN3. This activity is present in cells of hepatic and intestinal origin but absent in HeLa cells. Similar analysis showed that region H (-573 to -554) binds to the liver-specific factor HNF1/LFB1. Deletion of this region decreased hepatic and intestinal transcription 80 and 64% of control, respectively, suggesting that HNF1/LFB1 or a related activity contributes to optimal transcription but is not essential for the tissue-specific expression of the human apoA-II gene.

Apolipoprotein A-II↗
PubMed1991

Apolipoprotein B gene expression in rat intestine. The effect of dietary fiber.

The effect of the dietary fiber on apo B mRNA level was studied in the intestine of rats that were fed either fiber-free or high-fiber (30% sugar-beet fiber) low-fat diets for 3 weeks. The fiber diet studied does not affect jejunal apo B mRNA levels but decreases the level of ileal apo B mRNA. In the rat cecum, in both fiber-free and fiber groups, we failed to detect the apo B mRNA. The test fiber diet feeding markedly increased fecal bile salt and cholesterol excretions. We suggest that dietary fiber can modify apo B expression in the intestine. The increased fecal bile salt excretion might be involved in such a modification.

Animals↗
PubMed1991

Effect of dietary fish oil and corn oil on lipid metabolism and apolipoprotein gene expression by rat liver.

A 3-week fish oil diet induced in weanling rats a decrease in plasma lipids and liver triacylglycerol, and an increase in insulinemia, compared to a corn oil diet. At the same time, plasma apolipoprotein (apo) A-I was slightly lower and plasma heavy apo B/light apo B ratio was higher in fish-oil-fed than in corn-oil-fed rats. Hepatocytes obtained from fish-oil-fed and corn-oil-fed rats were used to examine how fish oil affects lipid and apolipoprotein synthesis and secretion. Primary culture of hepatocytes from fish-oil-fed rats displayed a lower ability to synthesize and secrete triacylglycerol than hepatocytes from corn-fed rats, as measured by mass determination or [U-14C]glycerol incorporation. Hepatocytes from fish-oil-fed rats exhibited a lower synthesis of cholesterol, measured by [14C]acetate incorporation, than hepatocytes from corn-oil-fed rats. This impairment was associated with an increase in beta-oxidation, a higher channeling of oleic acid into phospholipids, and a lower triacylglycerol/diacylglycerol ratio in hepatocytes from fish-oil-fed rats than in hepatocytes from corn-oil-fed rats. Incorporation of [35S]methionine into secreted apoB was reduced in hepatocytes from fish-oil-fed rats, but was not paralleled by a decrease in apo B mRNA. The appearance of degradative forms of apo B suggest an increase in apo B degradation in hepatocytes from fish-oil-fed rats. Incorporation of [35S]methionine into cellular and secreted apo A-I was lower in hepatocytes from fish-oil-fed rats than in hepatocytes from corn-oil-fed rats, and was not paralleled by any difference in the apo A-I mRNA level. Finally, [35S]methionine incorporation into cellular and secreted forms of apo E and apo A-I mRNA were reduced in hepatocytes from fish-oil-fed rats, compared with hepatocytes from corn-oil-fed rats. These combined data show that fish oil diet reduces triacylglycerol synthesis and secretion and affects apo B synthesis at a post-transcriptional level, and reduces cholesterol synthesis and affects apo E and apo A-I synthesis at a transcriptional and a post-transcriptional level.

Animals↗
PubMed1991

Nutritional regulation of apolipoprotein genes: effect of dietary carbohydrates and fatty acids.

The effect of nutritional factors on apolipoprotein gene expression by rat liver were studied. Dietary carbohydrates or fatty acids regulate the expression of apo E gene, by altering either gene transcription or mRNA stability. Conversely, apo AI regulation occurs at a post transcriptional level. In vivo and in vitro experiments gave contradictory results concerning apo B gene expression. The more dramatic changes in plasma lipids and apolipoproteins are obtained under dietary fish oil. Hepatocytes from fish oil-fed rats retain for several days modification in fatty acid metabolism, i.e. a shift in oleic acid channeling towards oxidation at the expense of esterification and a reduced ability to synthesize and secrete triacylglycerol. These modifications are paralleled with a decrease in the synthesis and in the secretion of apo Bs. Hepatocytes from fish oil fed rats secrete degradative forms of apo B which might result from either a sluggish VLDL synthesis and secretion or a more specific effect of n-3 long chain polyunsaturated fatty acid peroxidative products. Hepatocytes from fish oil fed rats exhibit a reduced ability to synthesize cholesterol, associated with a decrease in apo AI synthesis and secretion without any modification in apo AI mRNA. In contrast, the hepatocytes exhibit a concomitent decrease in apo E synthesis and secretion and in cellular apo E mRNA levels.

Animals↗
PubMed1991

Effect of magnesium deficiency on post-heparin lipase activity and tissue lipoprotein lipase in the rat.

Previous studies have provided evidence that Mg deficiency affects lipid metabolism. The present experiments were designed to assess whether the hypertriglyceridemia associated with Mg deficiency was related to alterations in post-heparin lipase activity (PHLA). Mg-deficient and control diets were pair-fed to weanling Wistar rats for eight days and plasma lipoproteins were separated into various density classes by sequential preparative ultracentrifugation. Triglycerides were significantly increased in chylomicrons and in the very low density lipoprotein, low density lipoprotein and high density lipoprotein (HDL) fractions. Cholesterol and phospholipid levels were significantly lower in the HDL fraction. PHLA in deficient rat was substantially lower than in control rats. The inverse correlation between plasma triglyceride concentration and PHLA strongly suggests that hypertriglyceridemia is the result of defective lipolysis of plasma triglycerides in Mg-deficient rats. Further examination of the PHLA was carried out by salt-mediated inhibition of lipoprotein lipase (LPL) and by heparin sepharose affinity chromatography and purified rat LPL antiserum. The results indicate that hepatic lipase is significantly decreased in Mg-deficient rats but the low PHLA is due mainly to a decline in LPL. However, total LPL activity, that is, both the intracellular and the extracellular pools of LPL in adipose tissue, heart and diaphragm, were unaffected by Mg deficiency. The results suggest that the decrease of LPL activity in the plasma of Mg-deficient rats may be due to a selective decrease in the heparin-releasable pool of enzyme.

Adipose Tissue↗
PubMed1991

Magnesium deficiency affects plasma lipoprotein composition in rats.

Weanling rats were pair-fed for 8 d with control and Mg-deficient diets containing 960 and 30 mg of Mg/kg, respectively. The marked reduction in plasma Mg levels indicated that the rats fed the Mg-deficient diet were indeed deficient. In the Mg-deficient rats the percent composition of triglycerides in VLDL, LDL and HDL was elevated and that of protein was reduced. Although the proportion of cholesterol was reduced in LDL and HDL, that of phospholipid was decreased only in HDL. Magnesium deficiency induced a decrease in the percent composition of apolipoprotein (apo) E and a relative increase in the apo C for VLDL. In HDL from Mg-deficient rats, the proportion of apo AI was higher than normal, apo AIV was lower than normal and apo E was virtually absent. The percent composition of oleic and linoleic acids was increased but that of stearic and arachidonic acids was depressed in both VLDL and HDL derived from Mg-deficient rats compared with pair-fed controls. Whether these alterations in lipoprotein profile contribute to hyperlipoproteinemia or are the results of the metabolic changes that produce hyperlipoproteinemia remain to be determined.

Animals↗
PubMed1991

Developmental changes in plasma apolipoproteins B and A-I in fetal bovines.

Plasma lipid, apolipoprotein (apo) B and apo A-I concentrations were measured in fetal calves in the age range of 4-9 months. The results were compared with those obtained from preruminant calves and cows. The studied lipids and apolipoproteins underwent quantitative underwent quantitative changes during development. Fetal calves, as compared to preruminant calves and cows, had a particularly low apo A-I concentration and a high apo B/apo A-I ratio. Unlike adult animals which have two forms of apo B, fetal calves had only high molecular weight apo B (apo Bh). During fetal development triglyceride, cholesterol and apo B concentrations decreased, but apo A-I concentrations remained constant.

Aging↗
PubMed1990

Partial apolipoprotein E-beta-galactosidase fusion protein expressed in Escherichia coli retains binding activity to the LDL(B/E) receptor.

A partial rat apo E-beta-galactosidase fusion protein was produced in Escherichia coli Y1089 infected with recombinant lambda GT11 obtained by immunoscreening of a rat liver cDNA library with an anti-rat LDL antiserum. Partial cDNA overlapped the apo E mRNA sequence coding for apo E binding domain towards the LDL(B/E) receptor up to codon for Arg-139. Fusion protein specifically bound to human fibroblasts. The high-affinity component exhibited a Kd of 5 x 10(-8) M and 4.1 x 10(5) sites per cell. Fusion protein binding to fibroblasts was mediated by their apo E moiety and not by beta-galactosidase since: (1) specific binding of fusion protein was competed out by human LDL; (2) beta-galactosidase did not compete with fusion protein binding; and (3) human fibroblasts from a patient with familial hypercholesterolemia, deficient in LDL(B/E) receptor, bound fusion protein 10-times lower than control fibroblasts. It was demonstrated that partial fusion protein retained the functional activity of the native apo E. However, compared to full-length native or engineered apo E, fusion protein was able to bind fibroblasts without being complexed with phospholipids. Fusion proteins might be a useful tool for studying the functional efficiency of the LDL(B/E) receptor and for mapping residues and domains involved in the binding process.

Apolipoproteins E↗
PubMed1990

Serum apolipoproteins B and A-I and naturally occurring fatty liver in dairy cows.

Serum lipids and apolipoprotein (apo) B and A-I concentrations were determined in 164 dairy cows which had undergone liver biopsy in early lactation. The animals were divided into groups according to fatty liver severity on the basis of hepatic triglyceride content. The serum free fatty acid (FFA) concentration was higher in cows that developed fatty livers than in normal cows, and it correlated highly with liver triglycerides. Serum total cholesterol and triglyceride levels did not correlate with hepatic triglycerides. Both apo B and apo A-I levels were significantly decreased in fatty liver cows. In particular, apo B levels showed a strongly negative correlation with liver triglycerides. The present results suggest that hepatic apolipoprotein synthesis is impeded in fatty liver cows.

Animals↗
PubMed1989

Apolipoprotein-E-gene expression in rat liver during development in relation to insulin and glucagon.

An apolipoprotein-E (apo-E) cDNA probe, cloned by immunoscreening of a lambda GT11 rat liver cDNA library, was used to further characterize the expression of the apo-E gene in rat liver during development, in relation to plasma insulin and glucagon levels. The apo-E mRNA level was low in fetus liver, then abruptly increased at birth and rose further during the suckling period. It returned to the level at birth in 10-week-old adults. These variations were paralleled with dramatic changes in plasma glucagon, which rose at birth and remained high during suckling. At the same time, the insulin/glucagon molar ratio fell. Administration of N6,O2-dibutyryl cAMP to 5-day-old rats resulted in a significant induction of liver apo-E mRNA. Moreover, liver apo-E mRNA rose in 10-h-fasted suckling rats as compared to controls, while plasma glucagon increased and the insulin/glucagon ratio decreased. Conversely, glucose feeding of suckling rats did not induce any increase in liver apo-E mRNA, the insulin/glucagon ratio was 10-fold higher than in fasted animals. Our results are consistent with liver apo-E gene expression being under the control of plasma glucagon and of the glucagon/insulin balance.

Animals↗
PubMed1989

Quantitative determination of apolipoprotein B in bovine serum by radial immunodiffusion.

1. In the present study we describe the first quantitative determination of apolipoprotein B (apo B) in bovine serum. 2. Immunosera and standard for radial immunodiffusion assay were raised using a purified apo B-containing lipoprotein obtained by ultracentrifugation and affinity chromatography. The assay working range was linear over the concentration of 4-70 mg/100 ml of protein of apo B standard. 3. Contrary to humans, bovine serum contains a low level of apo B-containing lipoproteins. The mean level of apo B in serum samples from cows at various stages of lactation was 16.0 +/- 0.6 mg/100 ml.

Animals↗
PubMed1989

Quantification of apolipoprotein A-1 in cow serum by single radial immunodiffusion.

A single radial immunodiffusion assay was developed to determine the concentration of the major apolipoprotein A-I in bovine serum. Assay was performed using agarose gel plates with monospecific rabbit antiserum. Standards made with bovine high density lipoproteins or serum 10 times diluted were applied in 3-microliters amounts to each well in the gel. The assay working range was 2 to 22 mg of apolipoprotein A-I. The intraassay and interassay CV were 3.7 and 4.9%, respectively. Using protein A-I. The intraassay and interassay CY were 3.7 and 4.9%, respectively. Using radial immunodiffusion assay, 23 serum samples from cows at various stages of lactation were analyzed. Apolipoprotein A-I was significantly increased in midlactation compared with concentrations in early lactation or dry period.

Animals↗
PubMed1988

Magnesium deprivation or short-term essential fatty acid deficiency in rats: effects on serum lipids, platelet fatty acid composition and arachidonic acid incorporation into platelet phospholipids.

The aim of this study was to evaluate the effect of short-term magnesium or essential fatty acid (EFA) deficiencies on plasma lipids, platelet fatty acid composition and [1-14C] arachidonic acid incorporation into platelet phospholipids. Weanling rats were fed purified diets (casein 20%, sucrose 70.5%, lipid 5%) for two weeks. The control and magnesium-deficient diets included corn oil as lipid source. The EFA-deficient diet included hydrogenated coconut oil. The fatty acid composition of serum lipids confirmed the linoleic acid deprivation in the EFA-deficient group. Significant changes in platelet fatty acid composition occurred in this limited period of time and arachidonic acid incorporation into platelet lipids was markedly increased. Magnesium deficiency induced hyperlipaemia. A significant decrease in the percentage of arachidonic acid in total serum lipids was observed, but fatty acid profile appeared quite different in the two deficiencies. In magnesium-deficient rats, the alteration in fatty acid composition of serum lipids was not associated with similar changes in fatty acid composition of platelet lipids. Arachidonic acid incorporation into platelet lipids was markedly increased in magnesium deficient animals as compared to control group. Relatively more arachidonic acid was incorporated into phosphatidylcholine and phosphatidylinositol when magnesium-deficient or EFA-deficient animals were compared to the control group.

Animals↗
PubMed1987

Microcomputer system for data acquisition and software handling in chromatography.

A complete, powerful yet simple and inexpensive microcomputer system for chromatography is described. It consists of an electronic interface card and an exploiting software, both controlled by an independent microcomputer. The interface includes all necessary circuits for digitizing the chromatographic signal and for controlling the actuators and the sensors connected with the chromatograph. The software, clock-interrupted, allows simultaneous data acquisition, mathematical treatment, connected plotting, and printing, and drives injection valves and gradient elution pumps. This system is both suitable for high-speed capillary gas chromatography and for high-performance liquid chromatography.

Chromatography↗
PubMed1987

Essential fatty acid deficiency during pregnancy in the rat: influence of dietary carbohydrates.

We investigated the role of gestation in the development of essential fatty acids (EFA) deficiency by comparing four groups of nonpregnant rats and four groups of pregnant rats fed either glucose or sucrose as carbohydrate source (61.5% kJ) and either corn oil (EFA) or hydrogenated coconut oil [saturated fat (SF)] as fat source (5% kJ). Pregnancy was a crucial period for the onset of EFA deficiency in sucrose-fed rats. The arachidonic acid content of plasma lipids and liver microsomes was lower in SF-sucrose pregnant rats than in SF-sucrose nonpregnant rats. The liver microsome delta 6- and delta 5-desaturase activities were higher in sucrose pregnant rats than in sucrose nonpregnant rats. In glucose-fed rats the EFA deficiency was less severe. delta 6- and delta 5-desaturase activities were higher in SF-glucose rats than in EFA-glucose rats, except for delta 5-desaturase of the pregnant rats, in which activity was high in both glucose-fed groups. This might explain the effect of glucose in preventing the onset of EFA-deficiency in pregnant rats fed an SF diet.

Animals↗
PubMed1986

Essential fatty acid uptake and esterification in primary culture of rat hepatocytes.

Primary cultures of adult rat hepatocytes were used to compare the uptake and esterification of essential polyunsaturated fatty acids (18:2, 20:3 and 20:4 of the n-6 series) with those of palmitic and oleic acids. The uptake of unesterified fatty acids was linearly related to the free fatty acid/albumin molar ratio for 14 h and did not depend on the unbound free fatty acid level. Whatever the initial free fatty acid/albumin molar ratio, it dropped to 0.5 +/- 0.1 mM after 14 h, thus showing that hepatocytes have a high capacity for clearing free fatty acids from the medium at high free fatty acid/albumin molar ratios. The free fatty acid uptake become saturable when the free fatty acid and albumin concentrations were raised and the free fatty acid/albumin ratio remained constant. This strongly suggests that albumin-hepatocyte interaction mediates free fatty acid uptake. This uptake was identical whatever the fatty acid tested and did not depend on the relative amounts of fatty acids when they were added simultaneously. Triacylglycerol accumulation and synthesis, monitored by labelled fatty acids, were related to the free fatty acid/albumin molar ratio and exhibited no specificity for the series of fatty acids tested. Triacylglycerols were enriched in all the fatty acids tested by up to 60%, and fatty acid incorporation into diacylglycerols and triacylglycerols reflected the free fatty acid composition of the medium. By contrast, neither the level nor the synthesis of phospholipids varied with free fatty acid/albumin, but the rate of phospholipid turnover depended on the fatty acids tested. Accumulation of these acids was smaller in phospholipids than in triacylglycerols. When linoleic and arachidonic acids were added together, phospholipids (especially phosphatidylethanolamine and phosphatidylinositol) were more enriched in arachidonic acid than triacylglycerols. This might be due to the specificity for fatty acid of the enzymes involved in phospholipid metabolism.

Animals↗