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P Besnard

Publications and source records attributed to P Besnard.

At least 37 records · Page 2Linked to original sources
PubMed1997

Intestinal lipid esterification and aging in mice and rats.

The effects of aging on lipid absorption, particularly on fatty acid glycerophospholipid and triacyl-glycerol esterification, were investigated in 2.5-, 12- and 24-month-old mice and rats. Two intestinal mucosa microsomal enzymes, involved in the dietary fatty acid absorption, were assayed: acylCoA:2-monoacylglycerol acyltransferase and acylCoA:1-lysophosphatidylcholine acyltransferase. In both mice and rats, the activities of both enzymes varied with the nature of the acyl-CoA. Indeed acylCoa:2-monoacylglycerol acyltransferase activities were significantly higher with oleoyl-CoA and linoleoyl-CoA than with palmitoyl-CoA and arachidonoyl-CoA, while acylCoA:1-lysophosphatidylcholine acyltransferase activities were highest with arachidonoyl-CoA. AcylCoA:2-monoacylglycerol acyltransferase activity did not decrease significantly with aging in mice or rats, whatever the acyl-CoA used. In contrast, acylCoA:1-lysophosphatidylcholine acyltransferase activity in the 24-month-old rats was significantly lower (-47%) than in 2.5-month-old rats, with oleoyl-CoA, linoleoyl-CoA and arachidonoyl-CoA. Simultaneously we observed that less glycerophospholipid esterification of oleic and linoleic acid occurs in older rats than in 2.5-month-old rats.

Aging↗
PubMed1997

Fatty acid regulation of fatty acid-binding protein expression in the small intestine.

The effects of dietary oil intake and fatty acid infusions on the expression of intestinal and liver fatty acid-binding proteins (I-FABP and L-FABP, respectively) were investigated in the small intestine of mice. A daily force-feeding for 7 days with 0.2 ml sunflower oil specifically increased L-FABP mRNA and protein levels in duodenum and proximal jejunum. This upregulation was mediated in time- and dose-dependent manners by a minute quantity of linoleic acid, the main fatty acid found in sunflower oil. The L-FABP induction was only found with long-chain fatty acids, with the nonmetabolizable, substituted fatty acid alpha-bromopalmitate being far more active. A hormonally mediated effect is unlikely because long-chain fatty acids induced L-FABP mRNA in the Caco-2 cell line cultured in serum-free medium. Therefore, long-chain fatty acids are strong inducers of L-FABP gene expression in the small intestine. In contrast to data found in the rat, I-FABP gene expression appears to be unaffected by a lipid-enriched diet in the mouse.

Animals↗
PubMed1997

Articular penetration is more likely in Garden-I fractures of the hip.

Plain radiographs show only two dimensions of a three-dimensional object. On anteroposterior and lateral radiographs an implant may appear to be safely within the head of the femur although surface penetration has occurred. We have attempted to identify this complication in the treatment of fractures of the femoral neck and have analysed the position of a screw or pin in the femoral head and neck on the basis of orthogonal frontal and lateral radiographs. A retrospective analysis of 60 cases of osteosynthesis of fractures of the femoral neck confirmed the risk of non-recognition of articular penetration or breaking of the cortex of the neck during surgery. Unrecognised screw penetration of the hip was observed in 8% and of the posterior part of the neck in 10%. The risk differs according to the type of fracture: it is greater in the coxa valga produced by Garden-I fractures of the femoral neck.

Aged↗
PubMed1996

Up-regulation of the expression of the gene for liver fatty acid-binding protein by long-chain fatty acids.

The role of fatty acids in the expression of the gene for liver fatty acid-binding protein (L-FABP) was investigated in the well-differentiated FAO rat hepatoma cell line. Cells were maintained in serum-free medium containing 40 microM BSA/320 microM oleate. Western blot analysis showed that oleate triggered an approx. 4-fold increase in the cytosolic L-FABP level in 16 h. Oleate specifically stimulated L-FABP mRNA in time-dependent and dose-dependent manners with a maximum 7-fold increase at 16 h in FAO cells. Preincubation of FAO cells with cycloheximide prevented the oleate-mediated induction of L-FABP mRNA, showing that protein synthesis was required for the action of fatty acids. Run-on transcription assays demonstrated that the control of L-FABP gene expression by oleate was, at least in part, transcriptional. Palmitic acid, oleic acid, linoleic acid, linolenic acid and arachidonic acid were similarly potent whereas octanoic acid was inefficient. This regulation was also found in normal hepatocytes. Therefore long-chain fatty acids are strong inducers of L-FABP gene expression. FAO cells constitute a useful tool for studying the underlying mechanism of fatty acid action.

Animals↗
PubMed1996

Localization and regulation of the putative membrane fatty-acid transporter (FAT) in the small intestine. Comparison with fatty acid-binding proteins (FABP).

The expression of the putative membrane fatty-acid transporter (FAT) was investigated in the small intestine. The FAT mRNA level was higher in the jejunum than in the duodenum and was lower in the ileum, as observed for cytosolic fatty-acid-binding proteins (FABP) expressed in this tissue. No FAT transcript was found in the stomach or colon. FAT mRNA was constitutively expressed in the epithelial cells located in the upper two thirds of villi, while it was undetectable in the crypt cells and submucosal cells. In jejunal mucosa, immunochemical studies showed that FAT protein was limited to the brush border of enterocytes. No fluorescence was found in the goblet cells. To determine whether FAT responded to changes in fat intake, as reported for FABP, the effect of two high-fat diets, which essentially contained either medium-chain fatty acids or long-chain fatty acids (sunflower-oil diet), was investigated. The sunflower-oil diet greatly increased FAT mRNA abundance throughout the small intestine. In contrast, a weak effect of medium-chain fatty acids was observed only in the jejunum. As found for FABP expression, treatment with the hypolipidemic drug bezafibrate affected FAT expression. These data demonstrate that FAT and FABP are co-expressed in enterocytes, as has been shown in adipocytes, myocytes and mammary cells. The data suggest that these membrane and cytosolic proteins might have complementary functions during dietary-fat absorption.

Animals↗
PubMed1996

Effect of bile on the intestinal bile-acid binding protein (I-BABP) expression. In vitro and in vivo studies.

Enterocytes actively transport bile acids from the ileal lumen to the portal blood. This physiological process greatly contributes to maintaining the bile acid homeostasis. However, little is known about the molecular mechanisms involved in this transport system. The effect of bile on gene expression of the intestinal bile-acid binding protein (I-BABP) expressed in the enterocytes was studied in vivo, using the by-pass method, and in vitro, using organ culture of ileum explants and Caco-2 cell line. The low cytosolic I-BABP concentration and I-BABP mRNA level found in diverted ileum was totally recovered when bile was added in the ileal lumen. Northern blot analysis of the ileal explants revealed a dose-dependent increase in the I-BABP mRNA in the presence of bile. In Caco-2 cells, the I-BABP transcript was dramatically increased in the presence of human bile while it was undetectable in the control cultures. These data offer the first evidence that biliary components regulate the I-BABP gene expressed in the enterocytes.

Animals↗
PubMed1995

Expression of fatty acid binding protein in the liver during pregnancy and lactation in the rat.

Expression of the liver fatty acid binding protein (L-FABP) has been studied in the liver of pregnant and lactating rats. The L-FABP concentration found in the cytosol by immuno-enzymatic assay (ELISA) was consistently higher in the dams during the pregnancy and the lactation than in the age-matched virgin females. Paradoxically, a decrease in the L-FABP mRNA level occurred in the maternal liver during the last days of the gestation. This level remained low on days 7 and 14 of the lactation. Since the transcription rate of the L-FABP gene was unchanged in the maternal liver, these data suggest a post-transcriptional regulation of the L-FABP during pregnancy and lactation in the rat. The nutritional adaptations occurring during pregnancy and lactation are not involved in this regulation since a chronic maternal food-restriction failed to correct these modifications. The mechanism of this regulation is presently unknown, but possibilities include hormonally mediated effects.

Animals↗
PubMed1995

Evidence for transcriptional induction of the liver fatty-acid-binding-protein gene by bezafibrate in the small intestine.

The effect of bezafibrate on cytosolic fatty-acid-binding-protein (FABPc) production along the small intestine has been investigated in mice. This drug increased the intestinal fatty-acid-binding-protein (I-FABPc) and liver fatty-acid-binding-protein (L-FABPc) mRNA levels in the duodenum. The extents of induction in the duodenum and in the liver are similar. However, the degree of stimulation gradually decreases along the length of the gut, no effect being found in the ileum. An efficient absorption of this drug as early as the proximal part of the small intestine may explain this phenomenon. The L-FABPc gene is silent in terminal ileum of mice, but a direct infusion of bezafibrate into the ileum switches it on. We used this original model to follow the time course of induction of the L-FABPc gene by bezafibrate. L-FABPc mRNA was first detected 4 h after fibrate infusion, reached a maximum level at 16 h and subsequently decreased at 24 h. This induction was totally blocked by cycloheximide. Sunflower oil also caused small increases in the L-FABPc mRNA levels. The transcriptional origin of the induction triggered both by bezafibrate and sunflower oil was demonstrated by run-on assays. These data indicate that (a) the transcription of the L-FABPc gene is induced by bezafibrate via de novo protein synthesis and (b) components of sunflower oil can transcriptionally activate the L-FABPc gene. Our results also demonstrate that the mouse terminal ileum is a useful system for studying the regulation of L-FABPc gene expression both in vivo and in vitro.

Animals↗
PubMed1994

[Femoral neck fractures: position of the implant, unrecognized articular penetration and its consequences].

INTRODUCTION: Only two dimensions of a three dimensional object are visible on plain roentgenograms. Therefore, on gross inspection of antero-posterior and lateral roentgenograms, a screw may project as being safely within the head of the femur even though penetration has occurred. This region may be referred to as a "blind zone". MATERIAL AND METHODS: Unrecognized screw penetration into the hip joint during internal fixation of femoral neck fractures was researched on intra operative roentgenograms of 30 patients. Unrecognized pin penetration through the posterior part of the neck was also analyzed on the same X Rays. RESULTS: Unrecognized screw penetration into the hip joint was observed in 20 per cent and penetration at the posterior part of the neck was observed in 10 per cent of cases. DISCUSSION: Several methods of determining screw position are described and discussed in this study.

Bone Nails↗
PubMed1993

Transcriptional induction of the fatty acid binding protein gene in mouse liver by bezafibrate.

The mechanism by which hypolipidemic peroxisome proliferators of the fibrate family induce the liver fatty acid binding protein in liver of rodents is unknown. In order to delineate the level at which this protein is induced, the transcriptional activity of the specific gene encoding for liver fatty acid binding protein was measured in isolated hepatocyte nuclei obtained from male Swiss mice daily force-fed during 7 days with 400 mg/kg body weight bezafibrate. This treatment induced a 4-fold increase in the liver fatty acid binding protein transcription rate. Liver fatty acid binding protein mRNA level, measured by Northern blot analysis and cytosolic content of this protein, analyzed by immunoblotting, increased concurrently. From these results we conclude that the increase in the cytosolic liver fatty acid binding protein level by bezafibrate is due to an enhancement of the transcription rate of the liver fatty acid binding protein gene. Whether the transcriptional effect is mediated by peroxisome proliferator-receptor remains to be elucidated.

Animals↗
PubMed1991

Effects of 1,25-dihydroxycholecalciferol and calcium on calcitonin mRNA levels in suckling rats.

The chronic administration of 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) to 9-day-old suckling rats induced no change on day 13 in the calcitonin (CT) mRNA steady-state level of thyroid glands measured by Northern hybridization. Thyroidal CT contents were decreased in relation to increased plasma calcium levels in animals treated with 0.1 or 1 microgram 1,25-(OH)2D3/kg. Using a lower dose (0.01 microgram/kg), neither plasma calcium, nor thyroidal CT contents were changed. No correlation was found between CT mRNA levels and thyroidal CT contents as well as for plasma CT levels and thyroidal CT contents since hormone in blood remained unchanged after treatment by the active vitamin D3 metabolite. Intraperitoneal calcium administration in fasted 13-day-old rats was associated with a 5-fold increase in plasma CT 30 min after injection, but CT mRNA levels were unchanged within 240 min. By contrast, stomach gavage with calcium in fasted 13-day-old rats induced a sustained increase in plasma CT (X2), and a 4-fold increase in the steady-state level of CT mRNA. Calcium per se is a potent stimulator of CT release in suckling rats, but did not change the amount of CT mRNA. However, gastrointestinal factors may be implied directly or indirectly in the increased CT mRNA level after calcium gavage. In conclusion, 1,25-(OH)2D3 which is known to affect CT gene expression in adult rats is ineffective in 13-day-old suckling rats. This observation may be related to developmental changes in the amount of 1,25-(OH)2D3 receptors of C cells.

Animals↗
PubMed1991

[Quantification of mRNA coding for enterocyte fatty acid binding proteins (FABP) in rats: effect of high lipid diet and starvation].

We have tested in adult rat the specificity and the sensitivity of two cDNA probes derived from recombinant plasmids pJG19 and pJG418. The Northern blot analysis of total RNA extracted from small bowel reveals 0.9 and 0.7 kb mRNA corresponding respectively to the I and L-FABPc mRNA. A linear relation occurs between the amounts of input total RNA and the quantities of specific mRNA found by hybridization with cDNA probes (r = 0.991 and r = 0.998 for I and L-FABPc respectively). We have also evaluated the effect of drastic nutritional status: a high fat diet containing 45% of lipids and a starvation of three days. A two fold increase in I and L-FABPc mRNA occurs in starved rats. By contrast, only the I-FABPc mRNA are slightly enhanced after the hyperlipidic diet (50%). These preliminary results, which must be confirmed by further experiments, suggest a differential nutritional regulation of I and L-FABPc gene expression in rat intestine.

Animals↗
PubMed1990

Ontogenesis of calcitonin mRNA in the rabbit.

Since plasma calcium levels are higher in the fetus than in the mother at the end of gestation, it has been suggested that calcitonin (CT) biosynthesis would be very active in the fetus. This hypothesis was tested in rabbit fetuses and newborns by measuring the amount of CT mRNAs found in the thyroid glands and the thyroidal CT stores. Dot-blot and Northern hybridizations with a specific CT cDNA probe (a BglII-NsiI fragment of the human CT cDNA) were used to determine the CT mRNA level. In fetuses, newborns, and mothers, only one molecular species of mRNA around 1 kb was detected by Northern hybridization with the specific CT cDNA probe. By dot-blot, CT mRNAs could be detected at 20 days of gestation on pooled fetal thyroid glands as a weak positive signal. The amount of CT mRNAs increased on day 24; at this stage they were also observed by Northern hybridization. During the last 6 days of gestation a 3-fold increase in CT mRNAs occurred in rabbit fetuses; concomitantly a 5-fold rise in the total thyroidal CT content was observed. Fetal plasma concentrations of both CT and calcium increased slightly between 24 and 30 days of gestation. After birth, the CT mRNA level was 10-fold increased between 2 and 30 days; these changes were not reflected in the plasma CT level but were probably accounted for by a rise in the number of C cells of the thyroid gland.

Animals↗
PubMed1989

Additive effects of dexamethasone and calcium on the calcitonin mRNA level in adrenalectomized rats.

Northern hybridizations were used to evaluate the effects of dexamathasone and calcium on calcitonin mRNA levels in adrenalectomized female rats. Two weeks after adrenalectomy, a 3.6-fold decrease in the calcitonin mRNA level was observed (28% vs 100% in sham-operated controls). After 5 days of dexamethasone treatment (1.5 mg/kg b. wt), a 2.6-fold rise in calcitonin mRNA occurred in adrenalectomized rats (73% vs 28%). This increment was higher when dexamethasone treated animals were injected with calcium (100% vs 73%). The effect of calcium on the calcitonin mRNA level of adrenalectomized rats treated or not with dexamethasone was similar, and additive in the former case. Our data suggest that calcium and dexamethasone elevate calcitonin mRNA by two different mechanisms.

Adrenalectomy↗
PubMed1988

Potassium administration and calcitonin mRNA level in the rat.

We have investigated the acute effects of elevated plasma potassium concentrations on the calcitonin (CT) mRNA level measured by dot-blot hybridization. Plasma CT levels were significantly increased (X2) 30 min after potassium administration (1.2 mmol, KCl/100 g body weight) in adult female rats; a trend towards increased values was observed 10 min after treatment. No change in plasma calcium concentration was induced by the elevated extracellular potassium levels. The amount of CT mRNA measured by dot-blot hybridization was statistically significantly increased 10 min and 30 min (around 47-55%) after potassium treatment. This finding was confirmed by a Northern blot analysis. It is suggested for the first time that the potassium-induced CT release is associated with a slight increase in CT mRNA level. The increased CT secretion was probably mediated through a rise in the ionized calcium concentration of the C-cell.

Animals↗
PubMed1988

Calcitonin-like immunoreactivity and calcitonin gene expression in the placenta and in the mammary gland of the rat.

Recently, the presence of monomeric CT in plasma and milk was reported by others in a lactating woman surgically thyroidectomized. Similarly, the placenta was thought to be a possible source of CT. Since such findings were based exclusively on immunological arguments, we have investigated the CT gene expression in these rat tissues. CT mRNAs were detected by dot-blot hybridization of total RNAs extracted from rat tissues with a 32P-labelled human CT cDNA probe. Subcellular fractions of each tissue were screened for CT-like immunoreactivity using two different antibodies. With one antibody, extracts of the mammary gland and placenta both produced full displacement of labelled human CT from the antiserum and serial dilutions of the extracts gave displacement curves parallel to that of synthetic human CT, which suggests immunological similarity. However, dilution curves were not parallel for the second antibody, and for both antisera, CT-like immunoreactivity was found in all subsellular fractions from nuclei to cytosols. Immunoprecipitation of translation products from poly (A)+RNAs of placenta showed two major bands around 30 kD. Under stringent conditions, the weak hybridization of placental RNAs seen by dot-blot under less stringent conditions disappeared. Northern analyses of total RNAs from the placenta failed to detect mRNA of 1 k base size like in thyroid glands, but hybridization under weak stringent conditions occurred with larger mRNAs (around 4.4 and 2.4 k bases). Immunoprecipitation of translation products from mRNAs of rat mammary glands showed three major bands around 46, 30 and 20 kD. Dot-blot hybridization of total RNAs extracted from mammary glands was also negative.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Calcitonin mRNA activity in genetically obese rats.

The etiology of the alterations in calcitonin (CT) secretion and plasma calcium of genetically obese (fa/fa) rats is unknown. In this study, we tested the postulate that there is an early occurrence of abnormalities in CT biosynthesis by thyroid glands of these rodents. Male genetically obese Zucker (fa/fa) rats and their lean littermates were therefore studied from 30 days to 10 months of age. Obese animals were characterized by hypercalcemia (delta approximately equal to 1 mg/dl), already present at 30 days of age. Increased thyroidal CT stores began at 6 weeks of age in fatty rats. Plasma CT levels were decreased in obese animals from 30 days to 10 weeks of age and were not different in leans and fatties 2 weeks later, but were higher at 10 months in fatty rats. Poly A + RNA were extracted from thyroid glands and subjected to translation assays. After SDS-PAGE, specific immunoprecipitates were autoradiographed and quantified by integration. A similar translation product with an apparent mol wt of 15,000 was specifically immunoprecipitated with CT antisera in obese (fa/fa) and lean Zucker rats at different ages. In 30-day-old fatty rats, a 50% decrease in translatable CT mRNA was observed in association with decreased plasma CT levels. In 12-week-old fatty rats, the translatable CT mRNA activity was unchanged or higher when compared to lean littermates, and clearly higher in 10-month-old fatty rats. The CT mRNA levels measured by dot-blot or northern blot hybridization paralleled at each stage studied the CT mRNA activity, determined by translation. It was concluded that in basal conditions, plasma CT level variations during development reflect the biosynthetic activity of C cells in genetically obese rats. The data presented in this study strengthen the point of an early occurrence of abnormalities in CT mRNA activity and in plasma calcium of fa/fa rats.

Aging↗