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G Bouvier

Publications and source records attributed to G Bouvier.

At least 19 recordsLinked to original sources
PubMed2005

Pesticide exposure of non-occupationally exposed subjects compared to some occupational exposure: a French pilot study.

Data about non-dietary exposure to different chemical classes of pesticides are scarce, especially in France. Our objective was to assess residential pesticide exposure of non-occupationally exposed adults, and to compare it with occupational exposure of subjects working indoors. Twenty unexposed persons, five gardeners, seven florists and nine veterinary workers living in Paris area were recruited. Nineteen residences, two greenhouses, three florist shops and three veterinary departments were then sampled. Thirty-eight insecticides, herbicides and fungicides were measured in indoor air with an air sampler for 24 h, and on hands by wiping them with isopropanol-wetted swabs. After extraction, samples were analysed by gas and high-performance liquid chromatography. Seventeen different pesticides were detected at least once in indoor air and twenty-one on the hands. An average of 4.2+/-1.7 different pesticides was detected per indoor air sample. The organochlorines lindane, alpha-endosulfan and alpha-HCH were the most frequently detected compounds, in 97%, 69% and 38% of the samples, respectively. The organophosphates dichlorvos and fenthion, the carbamate propoxur and the herbicides atrazine and alachlor were detected in more than 20% of the air samples. Indoor air concentrations were often low, but could reach 200-300 ng/m(3) in residences for atrazine and propoxur. Propoxur levels significantly differed between the air of veterinary places and other places (Kruskal-Wallis test, p<0.05) and dieldrin levels between residences and workplaces (p<0.05). There was a greater number of pesticides on hands than in air, with an average of 6.3+/-3.3 different pesticides detected per sample, the most frequently detected being malathion, lindane and trifluralin, in more than 60% of the subjects. Maximal levels (up to 1000-3000 ng/hands) were observed either in the general population or in workers, depending on the pesticide. However, no significant difference was observed between workers and general population handwipe pesticide levels. As expected, gardeners were exposed to pesticides sprayed in greenhouses. Florists and veterinary workers, whose pesticide exposure had not been described until now, were also indirectly exposed to pesticides used for former pest control operations. Overall, general population was exposed to more various pesticides and at levels sometimes higher than in occupational places. The most frequent pesticides in residences were not the same as in US studies but levels were similar. These preliminary results need to be confirmed in a greater number of residences from different parts of the country, in order to better assess pesticide exposure of the general population and its influencing factors.

Acetamides↗
PubMed2000

T cell development in TCR beta enhancer-deleted mice: implications for alpha beta T cell lineage commitment and differentiation.

T cell differentiation in the mouse thymus is an intricate, highly coordinated process that requires the assembly of TCR complexes from individual components, including those produced by the precisely timed V(D)J recombination of TCR genes. Mice carrying a homozygous deletion of the TCR beta transcriptional enhancer (E beta) demonstrate an inhibition of V(D)J recombination at the targeted TCR beta locus and a block in alpha beta T cell differentiation. In this study, we have characterized the T cell developmental defects resulting from the E beta-/- mutation, in light of previously reported results of the analyses of TCR beta-deficient (TCR beta-/-) mice. Similar to the latter mice, production of TCR beta-chains is abolished in the E beta-/- animals, and under these conditions differentiation into cell-surface TCR-, CD4+CD8+ double positive (DP) thymocytes depends essentially on the cell-autonomous expression of TCR delta-chains and, most likely, TCR gamma-chains. However, contrary to previous reports using TCR beta-/- mice, a minor population of TCR gamma delta+ DP thymocytes was found within the E beta-/- thymi, which differ in terms of T cell-specific gene expression and V(D)J recombinase activity, from the majority of TCR-, alpha beta lineage-committed DP thymocytes. We discuss these data with respect to the functional role of E beta in driving alpha beta T cell differentiation and the mechanism of alpha beta T lineage commitment.

Animals↗
PubMed2000

Association of STAT1, STAT3 and STAT5 proteins with the IL-2 receptor involves different subdomains of the IL-2 receptor beta chain.

Upon IL-2 stimulation of T lymphocytes, the IL-2 receptor (IL-2R) becomes phosphorylated on specific tyrosine residues which serve as docking sites for proteins containing SH2 or phosphotyrosine binding domains. To study the interaction of the IL-2Rbeta chain with Shc and STAT proteins, subdomains of the IL-2Rbeta chain were expressed as tyrosine-phosphorylated glutathione S-transferase fusion proteins and used to pull-down interacting proteins from Kit 225 cell lysates. These experiments provide direct biochemical evidence that binding to the IL-2R of the adaptor protein Shc requires phosphorylation of Tyr-338 in the IL-2Rbeta acidic subdomain. In addition, we report that STAT proteins that are activated by IL-2, i.e. STAT1, STAT3 and STAT5, indeed associate with the IL-2Rbeta chain. Both the A and B isoforms of STAT5 were found to associate with Tyr-510 of the IL-2Rbeta C-terminal region, depending on its phosphorylation. In contrast, STAT1 and STAT3 associated with the IL-2Rbeta chain through its acidic subdomain. These results indicate that the interaction between IL-2Rbeta and STAT1 or 3 does not require either phosphorylation of the receptor or even the presence of tyrosine residues of IL-2Rbeta. Thus, the IL-2R recruits STAT proteins through different modes of interaction.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Localization of NADPH-protochlorophyllide reductase in plastids of barley at different greening stages.

The localization of protochorophyllide (Pchlide) and of NADPH-protochlorophyllide oxidoreductase (POR, EC 1.6.99.1) within (etio)chloroplasts has been investigated at selected stages of greening of barley seedlings. Pchlide pigment and POR protein contents were evaluated in different plastid membrane fractions by fluorescence spectroscopy and immunoblot analysis using a monospecific polyclonal antibody raised against the purified enzyme. Fluorescence analysis showed the presence of Pchlide in both the envelope and thylakoid membranes. During greening, the Pchlide content, expressed on a total protein basis, decreased in thylakoid membranes, whereas it increased in the envelope membranes. POR proteins were detected mainly in thylakoid membranes at early greening stages. In contrast, the weak amount of POR proteins was associated more specifically with envelope membranes of mature chloroplasts. Whatever the greening stage, thylakoid-bound Pchlide and POR proteins were more abundant in the thylakoid regions which remained unsolubilized after mild Triton treatment used as standard procedure to prepare PS II particles. This suggests the preferential association of Pchlide and POR to the appressed regions of thylakoids.

Journal Article↗
PubMed2000

Definition of a T-cell receptor beta gene core enhancer of V(D)J recombination by transgenic mapping.

V(D)J recombination in differentiating lymphocytes is a highly regulated process in terms of both cell lineage and the stage of cell development. Transgenic and knockout mouse studies have demonstrated that transcriptional enhancers from antigen receptor genes play an important role in this regulation by activating cis-recombination events. A striking example is the T-cell receptor beta-chain (TCRbeta) gene enhancer (Ebeta), which in the mouse consists of at least seven nuclear factor binding motifs (betaE1 to betaE7). Here, using a well-characterized transgenic recombination substrate approach, we define the sequences within Ebeta required for recombination enhancer activity. The Ebeta core is comprised of a limited set of motifs (betaE3 and betaE4) and an additional previously uncharacterized 20-bp sequence 3' of the betaE4 motif. This core element confers cell lineage- and stage-specific recombination within the transgenic substrates, although it cannot bypass the suppressive effects resulting from transgene integration in heterochromatic centromeres. Strikingly, the core enhancer is heavily occupied by nuclear factors in immature thymocytes, as shown by in vivo footprinting analyses. A larger enhancer fragment including the betaE1 through betaE4 motifs but not the 3' sequences, although active in inducing germ line transcription within the transgenic array, did not retain the Ebeta recombinational activity. Our results emphasize the multifunctionality of the TCRbeta enhancer and shed some light on the molecular mechanisms by which transcriptional enhancers and associated nuclear factors may impact on cis recombination, gene expression, and lymphoid cell differentiation.

Animals↗
PubMed1999

A comparison of gamma and neutron irradiation on Raji cells: effects on DNA damage, repair, cell cycle distribution and lethality.

The Comet assay (microgel electrophoresis) was used to study DNA damage in Raji cells, a B-lymphoblastoid cell line, after treatment with different doses of neutrons (0.5 to 16 Gy) or gamma rays (1.4 to 44.8 Gy). A better growth recovery was observed in cells after gamma-ray treatments compared with neutron treatments. The relative biological effectiveness (RBE) of neutron in cell killing was determined to be 2.5. Initially, the number of damaged cells per unit dose was approximately the same after neutron and gamma-ray irradiation. One hour after treatment, however, the number of normal cells per unit dose was much lower for neutrons than for gamma rays, suggesting a more efficient initial repair for gamma rays. Twenty-four hours after treatment, the numbers of damaged cells per unit dose of neutrons or gamma rays were again at comparable level. Cell cycle kinetic studies showed a strong G2/M arrest at equivalent unit dose (neutrons up to 8 Gy; gamma rays up to 5.6 Gy), suggesting a period in cell cycle for DNA repair. However, only cells treated with low doses (up to 2 Gy) seemed to be capable of returning into normal cell cycle within 4 days. For the highest dose of neutrons, decline in the number of normal cells seen at already 3 days after treatment was deeper compared with equivalent unit doses of gamma rays. Our present results support different mechanisms of action by these two irradiations and suggest the generation of locally multiply damaged sites (LMDS) for high linear energy transfer (LET) radiation which are known to be repaired at lower efficiency.

Cell Cycle↗
PubMed1999

Biochemical analysis of interleukin-2 receptor beta chain phosphorylation by p56(lck).

Tyrosine phosphorylation of multiple proteins, including the receptor itself, is an initial event in IL-2 signaling and leads to recruitment of SH2 or PTB domain-containing proteins to the receptor. In this study, we have used subdomains of the IL-2 receptor beta chain (IL-2Rbeta) expressed in Escherichia coli as GST fusion proteins to identify the tyrosine residues that could be phosphorylated by p56(lck), one of the critical tyrosine kinases activated by IL-2. We report that recombinant p56(lck) phosphorylates in vitro tyrosine residues within the IL-2Rbeta chain but not those within the IL-2Rgamma chain. p56(lck) phosphorylates tyrosine residues 355, 358 and 361 but not 338 of the IL-2Rbeta chain acidic subdomain. Interestingly, phosphorylation of Tyr-358 appears to require the presence of either Tyr-355 or Tyr-361. p56(lck) also phosphorylates very efficiently the two tyrosines present in the IL-2Rbeta chain C-terminal region, Tyr-392 and Tyr-510. We also investigated the association of p56(lck) with the IL-2Rbeta chain which was found to depend on a short stretch of the IL-2Rbeta chain acidic subdomain, and to be independent of the presence of its tyrosine residues.

Base Sequence↗
PubMed1998

High benzo[a]pyrene diol-epoxide DNA adduct levels in lung and blood cells from individuals with combined CYP1A1 MspI/Msp-GSTM1*0/*0 genotypes.

Levels of anti-benzo[a]pyrene diol-epoxide DNA adducts were analysed by high-pressure liquid chromatography/fluorimetric detection in non-tumorous lung tissues from 20 lung cancer patients and in white blood cells from 20 polycyclic aromatic hydrocarbon exposed coke oven workers. All were current tobacco smokers. CYP1A1 mutations (MspI at 6235 nt, Ile-Val462) and GSTM1 deletion polymorphisms in each individual were analysed in genomic DNA by PCR/restriction fragment length polymorphism. Independently of the CYP1A1 genotype (1) all 23 samples in the two groups with non-detectable adducts (< 0.2 per 10(8) nt) were of GSTM1 active genotype; (2) the 17 samples with detectable adducts (> or = 0.2 per 10(8) nt) in the two groups were GSTM1*0/*0. The difference in adduct levels between GSTM1*0/*0 and GSTM1 active genotype was highly significant (p < 0.00005). Among GSTM1-deficient individuals (n = 17), a subgroup of 14 individuals with CYP1A1*1/*1 (wild-type, n = 7) or heterozygous genotype (*1/*2A or *1/*2B, n = 7) showed low levels of BPDE DNA-adducts (range: 0.2-1.3 per 10(8) nt). (3) Three individuals with the rare combination CYP1A1*2A/*2A or *2A/*B and GSTM1*0/*0 showed significantly higher adduct levels (median: 17.4 adducts/10(8) nt, range 1.9-44; p = 0.017). Therefore, combination of homozygous mutated CYP1A1 and GSTM1*0/*0 genotypes lead, at a similar or even lower smoking dose, to a stronger increase of anti-benzo[a]pyrene diol-epoxide DNA adduct levels than found in individuals with CYP1A1 and GSTM1 wild-type. These data provide a mechanistic understanding of epidemiological studies that correlated these 'at risk' genotypes with increased smoking-related lung cancers.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1997

A fixation procedure for ultrastructural investigation of synaptic connections in resected human cortex.

Electron microscopic investigations of the fine circuitry of human central nervous system require a well-preserved tissue ultrastructure. Because the deterioration of subcellular structures occurs rapidly in postmortem human brain, the use of a fixation by immersion of surgically resected human nervous tissue would be advantageous to investigate directly its synaptic circuitry. To obtain an optimal preservation of subcellular elements in immersion-fixed brain tissue, different conditions of fixation were first tested on 400 microns-thick sections of rat neocortex. Parameters tested were temperature of the fixative solution, concentrations of glutaraldehyde and of cacodylate buffer with or without microwave irradiation, and finally, the presence of dimethyl sulfoxide. The best ultrastructural preservation was obtained by immersing the tissue in 0.1 M cacodylate buffer, 3.0 mM CaCl2, 2% paraformaldehyde, 2.5% glutaraldehyde, and 2.5% dimethyl sulfoxide at 37 degrees C for 5 min and then at 4 degrees C for 4 h. This procedure of fixation was then applied to human neocortical tissue resected to alleviate temporal lobe epilepsy. This method led to good tissue preservation in addition to retaining the antigenicity to the inhibitory amino acid neurotransmitter, gamma-aminobutyric acid (GABA). Therefore, the tissue preservation obtained would permit these chemically defined connections to be investigated quantitatively at the electron microscopic level in resected human cortex.

Animals↗
PubMed1996

Deletion of the mouse T-cell receptor beta gene enhancer blocks alphabeta T-cell development.

Intrathymic T-cell development requires temporally regulated rearrangement and expression of T-cell receptor (TCR) genes. To assess the role of the TCR beta gene transcriptional enhancer (Ebeta) in this process, mouse strains in which Ebeta is deleted were generated using homologous recombination techniques. We report that mice homozygous for the Ebeta deletion, whether a selectable marker gene is present or not, show a block in alphabeta T-cell development at the CD4-CD8- double-negative cell stage, whereas the number of gammadelta+ T cells is normal, few CD4+CD8+ double-positive thymocytes and no alphabeta+ T cells are produced. DNA-PCR and RNA-PCR analyses of thymic cells from homozygous mutants showed no evidence of TCR beta gene rearrangement although germ-line Vbeta transcripts were detected at a low level, in heterozygous T cells, the targeted allele is not rearranged. Thus, deletion of Ebeta totally prevents rearrangement, but not transcription, of the targeted beta locus. These data formally establish the critical role played by Ebeta in cis-activation of the TCR beta locus for V(D)J recombination during alphabeta T-cell development.

Aging↗
PubMed1996

Multiple subpial transection: report of 7 cases.

7 cases of pure multiple subpial transection (MST) without associated cortical resection, for treatment of pharmaco-resistant partial epilepsy localized in highly functional cortical area, are reported. The transections were performed following the technique described by Morrell. The follow-up period ranged from 1 to 4 years. MST induced no significant neurological handicap: only 2 patients experiencing a transitory sensory-motor deficit and with total recovery within 1 month. With respect to seizures, 5 patients were improved with a decrease in seizure frequency of 100, 95, 75, 60 and 40%, respectively. Complex partial seizures changed postoperatively into simple partial seizures in 1 case. In conclusion, this procedure seems to be adequate, although no statistically significant results are available at this time. In our series, we believe failures could be attributed to either a very restricted area of transection or to an incorrect delimitation of the epileptic focus.

Adult↗
PubMed1995

Altered T cell development in mice with a targeted mutation of the CD3-epsilon gene.

To determine which CD3 components are required for early T cell development, we generated mice with a targeted mutation of the CD3-epsilon gene and characterized their T cell populations relative to those found in CD3-zeta/eta-and recombinase activating gene (RAG)-deficient mice. In the absence of intact CD3-epsilon subunit, thymocytes do not progress beyond the CD44-/lowCD25+ triple-negative stage and appear to be arrested at the very same developmental control point as RAG-deficient thymocytes. In contrast, the disruption of the CD3-epsilon/eta gene does not totally abrogate the progression through this control point. CD3-epsilon-deficient thymocytes do rearrange their T cell receptor (TCR) beta gene segments and produce low levels of full-length TCR beta transcripts. Taken together, these results establish an essential role for the CD3-epsilon gene products during T cell development and further suggest that the CD3-epsilon polypeptides start to exert their function as part of a pre-TCR through which CD44-/lowCD25+ triple-negative cells monitor the occurrence of productive TCR beta gene rearrangements. Finally, the absence of intact CD3-epsilon polypeptides had no discernible effect on the completion of TCR gamma and TCR delta gene rearrangements, emphasizing that they are probably not subjected to the same epigenetic controls as those operating on the expression of TCR alpha and beta genes.

Animals↗
PubMed1995

T cell development in TCR-alpha beta transgenic mice. Analysis using V(D)J recombination substrates.

The major pathway of intrathymic T cell differentiation leads CD4-8- (DN) T lineage-committed precursors to TCR-alpha beta+ CD4+8- or CD4-84+ (SP) T lymphocytes. The expression of functionally rearranged TCR-alpha beta transgenes (Tg-TCR) may influence thymocyte development by affecting the various selection events that control T cell differentiation. To gain insights into these processes, we have produced double transgenic animals carrying V(D)J recombination substrates in addition to the MHC class I (H-2Kb) allospecific KB5C20 Tg-TCR. We have analyzed substrate rearrangements in purified populations of Tg-TCR+ thymocytes in the situation of positive or negative selection. The profile of rearrangements found in SP thymocytes, positively selected for the Tg-TCR, suggests that expression of the KB5C20 Tg-TCR has only a minimal influence on substrate V(D)J recombination in cells differentiating along the major alpha beta T cell developmental pathway. In contrast, Tg-TCR+ DN thymocytes, in both positively and negatively selecting haplotypes, presented a profile that implies premature cessation of substrate rearrangements. This profile was maintained in peripheral Tg-TCR+ DN cells and was distinct from the one found in CD25+, alpha beta+, or gamma delta+ DN cells purified from mice transgenic for the recombination substrates only. These results are discussed with respect to the possible origin and differentiation pathway of Tg-TCR+ DN and SP cells.

Animals↗
PubMed1995

Characterization of macromolecular lignins as Epstein-Barr virus inducer in foodstuff associated with nasopharyngeal carcinoma risk.

Epstein-Barr virus (EBV)-inducing activity was previously demonstrated to occur in various foodstuffs, including dried salted fish in southern China and 'harissa', a homemade spice mixture in Tunisia, whose consumption is epidemiologically associated with an increased risk for developing nasopharyngeal carcinoma (NPC). For the isolation and the characterization of active ingredients in harissa, we used as a rapid screening assay the induction of the chloramphenicol acetyltransferase (CAT) activity through the EBV-DR promoter in DR-CAT Raji cells. After fractionation of harissa and column chromatography on Sepharose-CL4B, the major inducing activity was associated with a macromolecular fraction which was chemically characterized as liginin-containing complexes. The active material enhanced EBV-DR induction with an activity comparable to the tumor promoter and strong EBV inducer, 12-O-tetradecanoylphorbol-13-acetate. Experiments with inhibitors of protein kinase C-related pathways suggested that the EBV-inducing activity of lignin fractions operates through a different pathway. Our results on the presence of specific lignin fractions in high-risk food items that can induce important cellular functions linked to tumor promotion are discussed in relation to NPC genesis and etiology.

Herpesvirus 4, Human↗
PubMed1994

Relationship between phagosome acidification, phagosome-lysosome fusion, and mechanism of particle ingestion.

The fate of pathogens ingested by macrophages is dependent on phagosome acidification and fusion with different intracellular vesicles. Whereas the mode of particle recognition by the phagocyte seems the main determinant of phagosome-lysosome fusion, the influence of membrane reorganization, fusion events, and cell activation in phagosome acidification is not well known. We looked for a relationship between the nature of receptors involved in phagocytosis, phagosome acidification, and phagosome-lysosome fusion. Murine macrophage-like P388D1 cells were made to ingest sheep erythrocytes coated with immunoglobulin G (EIgG) or IgM and complement (EIgMC) or treated with glutaraldehyde and periodate (EGP). The following results were obtained: (1) As expected, the adhesion of the three particle types was differentially inhibited by monoclonal antibodies specific for Fc gamma RII and CD11b/CD18. (2) The phagosomes containing all three particle types displayed similar acidification kinetics with a pH decrease to 6 within the first 10 min after ingestion. (3) Only phagosomes containing EIgG or EIgMC were fused with peroxidase-loaded secondary lysosomes. (4) Coating EGP with IgG only partially restored fusion, even when the surface density of IgG was markedly higher than found on EIgG. It is concluded that phagosome acidification and fusion are regulated by different mechanisms. Also, the lack of fusion observed with EGP is not entirely accounted for by the absence of stimulation of suitable receptors on the phagocyte membrane, because it cannot be restored by providing such a stimulus.

Animals↗