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Biomedical subjects

P Lemaire

Publications and source records attributed to P Lemaire.

At least 19 recordsLinked to original sources
PubMed1992

Subterminal hydroxylation of lauric acid by microsomes from a marine fish.

Microsomes from the liver of sea bass (Dicentrarchus labrax) were shown to hydroxylate lauric acid at subterminal positions. The cytochrome P-450 system converted lauric acid to several mono-hydroxylated metabolites including omega-1 hydroxylaurate, which was the major metabolite (44% of total products). In addition, omega-2, omega-3, omega-4 and a small amount (2.3%) of omega hydroxylaurates were found. Reaction products were identified using thin-layer chromatography (TLC) and gas chromatography/mass spectrometry (GC/MS). Oxidation reactions were dependent upon O2 and NADPH, and did not occur with boiled microsomes or in the presence of a mixture of CO/O2. Hydroxylation proceeded linearly up to 20 min at 28 degrees C for protein concentrations below 380 micrograms. Treatment of fish with benzo(a)pyrene (BP) (20 mg/kg) drastically increased xenobiotic metabolism (ECOD, EROD and BPMO activities), but no difference in laurate hydroxylase activity was observed between untreated and treated fish. Starvation strongly enhanced laurate hydroxylase activity, and resumption of feeding reduced by half this increase of activity. In all of the experiments we did not observe any modification of the regioselectivity of lauric acid hydroxylation by this microsomal in-chain hydroxylating system. We suggest that cytochrome P-450 enzymes involved in lauric acid and xenobiotics metabolism are regulated independently.

Animals↗
PubMed1992

The uptake, metabolism, and biological half-life of benzo[a]pyrene administered by force-feeding in sea bass (Dicentrarchus labrax).

The kinetics of uptake and metabolism of benzo[a]pyrene (BaP) were studied in various tissues of a marine fish, the sea bass (Dicentrarchus labrax), after intragastric administration of pellets containing a 14C-labeled compound. Only 25% of injected radioactivity was detected and it was found only in intestine, gallbladder, liver, and kidney. The major part of radioactivity was found in gallbladder (85% of the whole body radioactivity). The calculated half-lives determined after the decrease in radioactivity measured in these tissues were 8.2, 3.5, 3.3, and 0.8 days for liver, gallbladder, intestine, and kidney, respectively. The kinetics of distribution of radioactivity between alkali and hexane tissue extracts showed the high metabolization potential of intestine which represents the main site of BaP uptake by this route of exposure. The other organs received mainly metabolites brought by general blood circulation. Intragastric administration as an experimental exposure route compared to other exposure patterns and particularly intraperitoneal injection, which has been used previously in the same species and under the same experimental conditions for the same kind of study, is discussed.

Administration, Oral↗
PubMed1992

Ultrastructural changes induced by benzo[a]pyrene in sea bass (Dicentrarchus labrax) liver and intestine: importance of the intoxication route.

The ultrastructural effects of benzo[a]pyrene (BaP) on sea bass (Dicentrarchus labrax) liver and intestine were studied after experimental intoxication by two different routes: intraperitoneal injection and force-feeding. In both hepatocytes and enterocytes, the main structural perturbations concerned a large development of both rough and smooth endoplasmic reticulum and a great increase in the number of vacuoles and lysosomes in BaP-treated fish. After 17 days of contamination, some nuclear changes were observed, indicating the high reactivity of BaP metabolites which form covalent adducts with DNA and the long-term toxicity of this compound. However, in the intestine, after force-feeding intoxication, more perturbations were seen, particularly concerning the mitochondria. Both organs were altered in a different way with respect to the intoxication route. In BaP intraperitoneal injected fish, the liver was the first injured organ and presented heavier injuries than intestine. In force-feeding treated fish, the intestinal epithelium was the first concerned tissue and it was highly modified after BaP intoxication. The importance of the intoxication pathway in the effects of BaP on liver and intestine was discussed with special reference to their role in BaP uptake, metabolism, and distribution in the organism.

Administration, Oral↗
PubMed1992

[Influence of sampling techniques on blood sodium, potassium and hemoglobin concentration measured by a blood gas analyser].

A study was carried out to assess the influence of sampling technique on sodium, potassium and haemoglobin blood concentrations measured simultaneously with a bedside blood gas analyser (Ciba Corning 288) and in the central laboratory. Blood samples from forty intensive care unit patients were used to test cight techniques: capillary tubes (Radiometer & Corning), preheparinized syringes (Terumo 2.5 ml, Sherwood 1 and 3 ml, Corning 1 ml) and Radiometer 2 ml) and a conventional syringe (Plastimed) which was rinsed with heparin just before use. Each result was compared with that obtained by the laboratory. For haemoglobin concentrations, the results were underestimated by the bedside analyser with Terumo, Corning, Radiometer and Plastimed syringes. The differences between results varied with the haemoglobin concentration, and precision was low: 38 to 55% of results showed a difference of more than 1 g.dl-1, and 13 to 25% a difference of more than 2 g.dl-1. The results obtained with the capillary tubes and the preheparinized syringes (Sherwood) showed differences independent of the value, as well as higher precision: 13 to 20% of values differed more than 1 g.dl-1, and 0 to 3% more than 2 g.dl-1. The capillary tubes moderately overestimated the haemoglobin concentration (+0.02 to +0.65 g.dl-1) while Sherwood's syringes underestimated it (-0.48 to -0.94 g.dl-1). For the sodium and potassium concentrations, the eight methods gave results similar to those obtained by the laboratory. It is concluded that these modules for bedside biological analysis, when used in optimal conditions, rapidly provide reliable results for some parameters.

Blood Gas Analysis↗
PubMed1992

[Traumatic false aneurysm associated with closed fractures of the mandible. Apropos of 3 cases].

The authors report 3 cases of trauma induced false aneurysm (internal maxillary, external carotid and internal subpetrous carotid arteries) associated to closed mandibular fractures. These rare vascular complications of ill-defined pathogeny are often due to high speed facial impact. Clinical presentation is polymorphous (pseudo-parotidis, neurological deficit) and arteriography is the main step of the paraclinic investigation. The treatment essentially depend upon both the location and the evolutivity of the false aneurysm.

Adult↗
PubMed1991

Reproductive cycle and heavy metals in the organs of red mullet, Mullus barbatus (L.), from the northwestern Mediterranean.

Concentrations of the heavy metals Cd, Cu, Fe Mn, V and Zn have been measured in the principal tissues of the red mullet, Mullus barbatus (L.), during a complete sexual cycle. By comparison of metal levels during the reproductive and non-reproductive periods, it was found that concentrations as well as total amounts of Cu, Mn and Zn in liver and gonads of male and female mullets were dependent upon the stage of the sexual cycle. No relationship with the sexual cycle was noted for these metals measured in muscle, kidney, spleen or pyloric caecum. Because of the observed variation in liver and gonad metal concentrations, these tissues appear to be poor indicators of ambient levels of metals in the surrounding waters. However, muscle may prove useful as an indicator tissue owing to its apparent independence of effects of the sexual cycle.

Animals↗
PubMed1991

Seasonal and sex-linked variations in hepatic and extrahepatic biotransformation activities in striped mullet (Mullus barbatus).

Microsomal cytochrome P450 content, NADPH-cytochrome c reductase, and phase I (ethoxycoumarin and ethoxyresorufin O-dealkylases) and phase II (glutathione S-transferase and UDP-glucuronyltransferase) activities were studied in the liver and intestine of the striped mullet (Mullus barbatus) for 8 months (before and during sexual maturation). Biotransformation activities were much lower in extrahepatic tissues than the corresponding activities in the liver. Intestinal and hepatic biotransformation activities presented similar seasonal fluctuations: Phase I activity increased from October to February (during water cooling) and generally decreased before spawning; Phase II activity was not greatly different. Moreover, NADPH-cytochrome c reductase, ethoxyresorufin O-dealkylase, and glutathione S-transferase activities were measured in the kidney during the sexual maturation period. Renal phase I and phase II activities showed very little fluctuation during the 5 months studied. Cytochrome P450 and ethoxycoumarin and ethoxyresorufin O-dealkylases exhibited sex-linked differences during sexual maturation, whatever the tissue: in the liver the values are higher in male fish, whereas in the intestine and kidney they are lower.

Animals↗
PubMed1991

Mixed-function oxygenase enzymes as tools for pollution monitoring: field studies on the French coast of the Mediterranean Sea.

1. MFO enzyme activities were measured in microsomes from whole mussels (Mytilus galloprovincialis) comber livers (Serranus cabrilla), or Posidonia oceanica etiolated tissues, and PAH contents were determined in sediments collected in coastal locations of the French Riviera and Corsica during 3 oceanographic cruises in 1987-1988. 2. BaP activities in mussel and EROD activities measured in fish were strongly correlated to the log of PAH content in sediments. The first results for CA4H in Posidonia showed significant differences related to PAH pollution levels. The increase in MFO activities measured in Corsica in summer 1988 indicated a recent petroleum contamination.

Animals↗
PubMed1990

The uptake metabolism and biological half-life of benzo[a]pyrene in different tissues of sea bass, Dicentrarchus labrax.

The disposition of polycyclic aromatic hydrocarbons in aquatic organisms is of interest from the viewpoint of both animal and human health. The kinetics of uptake and metabolism of benzo[a]pyrene (BaP) were studied in various tissues of the marine fish, sea bass, upon intraperitoneal injection of the compound. A decrease in radioactivity occurred in all tissues and the calculated half-lives were 12.4 days for fat, 6.5 for kidney, 5.1 for intestine, 4.8 for gallbladder, 4.5 for spleen, 2.9 for muscle, 2.4 for whole body, 2.3 for gonads, 2.3 for gills, and 2.2 for liver. The kinetics of distribution of radioactivity between alkali and hexane tissue extracts were determined in order to assess the overall metabolic potential of various organs. The liver, intestine, gills, and kidney displayed a relatively high metabolic potential in comparison with the spleen, muscle, gonads, and fat. The significance of the observations with respect to understanding mechanisms of toxicity is briefly discussed. Attention is specifically drawn to the presence of a fairly active metabolism or metabolite redistribution system in the muscle and the potential for exposure of blood cells to metabolites via hydrocarbon transformation processes in the spleen. This in vivo study, in which hydrocarbon disposition was studied in various tissues, also supports the hypothesis that polycyclic aromatic hydrocarbons should not bioaccumulate to any significant degree in fish and that exposure of humans to such compounds through the consumption of fish products can be expected to be minimal.

Animals↗
PubMed1990

The serum-inducible mouse gene Krox-24 encodes a sequence-specific transcriptional activator.

The mouse gene Krox-24 is transiently activated during cell cycle reentry. It encodes a protein with three zinc fingers similar to those of the transcription factor Sp1. Here we present a biochemical characterization of the gene products. Krox-24 mRNA is translated into two proteins of 82 and 88 kilodaltons, designated p82Krox-24 and p88Krox-24, respectively. p82Krox-24 is initiated at the first AUG codon of the open reading frame, whereas synthesis of p88Krox-24 starts at a non-AUG codon located upstream. Both proteins were synthesized in HeLa cells infected with recombinant vaccinia viruses expressing Krox-24 cDNAs. Under these conditions, they were found phosphorylated on serine residues and glycosylated. The availability of the proteins made possible the determination of the DNA recognition sequence. In vitro, Krox-24 bound specifically to the sequence 5'-GCG(C/G)GGGCG-3'. This sequence is similar but not identical to the Sp1 target sequence. Insertion of an oligomer for the binding site in cis, close to the herpes simplex virus thymidine kinase promoter, rendered this promoter responsive to Krox-24. Krox-24 is therefore a sequence-specific transcriptional activator. Krox-24-binding sites were found upstream of several serum-inducible genes, raising the possibility that Krox-24 is involved in the regulation of these genes.

Amino Acid Sequence↗
PubMed1976

[Current treatment of testicular cancers].

The treatment and prognosis of dysembryoma of the testis have been transformed by the dissection of retroperitoneal nodes and by combination chemotherapy as early as possible. Routine retroperitoneal node dissection followed by early and prolonged chemotherapy lead to a hope of cure in more than 75% of cases of dysembryoma of the testis. Similar early chemotherapy is effective and indicate for choriocarcinoma of the testis and retroperitoneal node dissection may be of value in tumours in which the chorial element is "minor".

Antineoplastic Agents↗