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J Aigueperse

Publications and source records attributed to J Aigueperse.

63 records · Page 4Linked to original sources
PubMedDate not supplied

Cholesterol turnover in swine plasma lipoproteins.

The kinetics of free and esterified cholesterol labeling were studied in the plasma lipoproteins of three groups of six adult Large White sows, after either an intravenous injection of autologous red cells previously labeled with [3H]-cholesterol, an intravenous injection of [14C]-acetate, or a [14C]-cholesterol labeled meal. The specific radioactivities became equal in plasma and red cell cholesterol about 96 hours after each pulse of radioactive cholesterol. This finding indicates that red cell cholesterol is completely exchangeable in vivo, with a turnover time of 8.5 hours. The VLDL were shown to play a preferential role in the transport in the plasma of newly synthetized cholesterol. This role is shared with chylomicrons in the transport of absorbed dietary cholesterol, which appears in the plasma mainly as esterified cholesterol. Cholesteryl esters of VLDL are not the main source for those of LDL, which could be labeled by intraplasmatic exchanges or transfers of esterified cholesterol.

Animals↗
PubMedDate not supplied

Chronic contamination with 137cesium in rat: effect on liver cholesterol metabolism.

After the Chernobyl nuclear accident, epidemiological studies on human populations living in 137Cs-contaminated areas revealed the increase frequencies of thyroid cancer and evoked the apparition of cardiovascular diseases, hormonal effect, liver alteration, and lipid disorder. Actually, it raises a problem of public safety for the populations living on these territories that are exposed to low levels of 137Cs during a long period through food. Then it is necessary to study potential effect of this chronic contamination. To mimic this situation, the authors investigate the potential biological effects of chronic exposure to 137Cs at a postaccidental dose (150 Bq/rat/day) on hepatic metabolism of cholesterol in rat. Plasma lipid level, gene expression and activity were analyzed. It was observed that in 137Cs-exposed rats, gene expression of low-density lipoprotein receptor (LDLr), apolipoprotein B (apoB), and liver X receptor alpha (LXRalpha) are increased (95%, p < .05; 34%, p < .05; 20%, p < 0.05, respectively), whereas transporter adenosine triphosphate-binding cassette transporter G5 (ABCG5) is decreased (42%, p < .05). In addition, cytochrome P450 27A1 (CYP27A1) activity is increased (34%, p < .05) in contaminated rat liver. In conclusion, the results suggest that 137Cs contamination at low-level induces molecular modifications of the liver cholesterol metabolism without leading to a dysregulation of its homeostasis. These results suggest that chronic long term exposure at low-level of 137Cs may evolve to lipid disorder.

ATP Binding Cassette Transporter, Subfamily G, Mem↗
PubMedDate not supplied

[Cytochromes P450: xenobiotic metabolism, regulation and clinical importance].

Cytochromes P450 (CYPs) are a superfamily of 57 genes coding for drug metabolizing enzymes and endobiotic metabolizing enzymes (steroids, eicosanoids, vitamins...). This is the main metabolizing enzyme system for foreign compounds, including drugs, which has a primary role in organism protection against potential harmful insults from the environment (pollutants, pesticides...). The CYPs regulation is essentially transcriptional: nuclear receptors are recognized as key mediators for the control of drug metabolizing enzymes. Their ligands are exogenous and also endogenous molecules that can up-regulate or down-regulate these transcription factors. Treatment with drugs or xenobiotics, which are nuclear receptor agonists or antagonists, can lead to severe toxicities, loss of therapeutic effect or endobiotic metabolism disorders. Genetic polymorphisms of these enzymes have an important role in their activity and must be taken into account during drug administration. Then, CYP activity depends on genotype and environment; this is recently used as biomarker to determine human exposure to environmental molecules or to predict the susceptibility to certain pathologies.

Cytochrome P-450 Enzyme System↗