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C Dupuy

Publications and source records attributed to C Dupuy.

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

Regulation of the thyroid NADPH-dependent H2O2 generator by Ca2+: studies with phenylarsine oxide in thyroid plasma membrane.

Pig thyroid plasma membranes contain a Ca(2+)-dependent NADPH:O2 oxidoreductase, the thyroid NADPH-dependent H2O2 generator. This provided the H2O2 for the peroxidase-catalysed synthesis of thyroid hormones. The effect of the tervalent arsenical, phenylarsine oxide (PAO), on the NADPH oxidase was studied. PAO caused two directly related dose-dependent effects with similar half-effect concentrations of PAO (3 nmol of PAO/mg of protein): (i) partial inactivation of H2O2 formation by the Ca(2+)-stimulated enzyme, and (ii) desensitization of the enzyme activity to Ca2+. PAO had no effect on membranes that had been Ca(2+)-desensitized by alpha-chymotrypsin treatment. The NADPH oxidase in membranes treated with excess PAO had the same Vmax with and without Ca2+. This value was half the Vmax of the native enzyme. However, the K(m) for NADPH determined with Ca2+ (18 microM, identical with that of the native enzyme) was approx, one-third of the K(m) measured without Ca2+, showing the direct action of Ca2+ on the PAO-enzyme complex. PAO had the same effects, partial inactivation and Ca2+ desensitization, on the NADPH: ferricyanide oxidoreductase activity of the NADPH oxidase, suggesting that PAO acts on the flavodehydrogenase entity of the enzyme. Both partial inactivation and Ca2+ desensitization were completely and specifically reversed by 2.3-dimercaptopropanol, partly reversed by dithiothreitol and not reversed by 2-mercaptoethanol, indicating that PAO binds to vicinal thiol groups. These results suggest that thiol groups are involved in the control of thyroid NADPH oxidase by Ca2+; PAO bound to vicinal thiols might alter the structure of the enzyme so that electron transfer occurs without Ca2+ but more slowly.

Animals↗
PubMed1997

Cell mediated immunity induced in mice by HPV 16 L1 virus-like particles.

Recombinant human papillomavirus (HPV) type 16 L1 virus-like particles (VLPs) expressed in the baculovirus system were used to investigate the cellular immune response to human papillomavirus type 16. The cell-mediated immune response was evaluated through immunization of mice with HPV 16 L1 virus-like particles using a lymphoproliferation assay and cytokine production and cytometric analysis of lymphocyte subsets. A significant proliferative response was observed which was associated with secretion of both interferon-gamma and interleukin-2. FACS analysis of splenic lymphocytes revealed that CD8+ T-cells were increased in the immunized mice. These results demonstrate that HPV 16 L1 VLPs induce a T-cell response characterized by a Th1 profile and confirm that the HPV 16 VLP is a reasonable candidate for vaccine development.

Animals↗
PubMed1997

Effects of the civil war in central Mozambique and evaluation of the intervention of the International Committee of the Red Cross.

In October 1994, a retrospective study of mortality of children was conducted in Maringué, a district of central Mozambique. Estimates based on maternity histories of 1503 women aged 15-60 years revealed complex changes in the under-5 death rate. During the colonial period (1955-1974), mortality declined from 373 to 270 per 1000. During the civil war period (1975-1991), mortality increased rapidly to reach a peak of 473 per 1000 in 1986. It declined again thereafter and reached a plateau of 380 in 1991. A health intervention conducted by the International Red Cross Committee since 1992 further reduced mortality to 269 per 1000 in 1994. Most of the 1992-1994 decline was attributable to vaccinations, in particular measles and tetanus immunizations, and to Vitamin A supplementation.

Adolescent↗
PubMed1997

[Case control studies of the risk factors for deep-vein thrombosis in an adult population hospitalized in internal medicine].

BACKGROUND: The ain of this study was to demonstrate risk factors for deep-vein thrombosis in adults in a hospital setting. MATERIALS AND METHODS: From May 1993 to Februrary 1995, 233 patients hospitalized in the internal medicine unit at the Montpellier University Hospital for deep-vein thrombosis were included. Each case was matched to a control case for age, hospitalization unit, and use or not of anti-thrombosis prophylaxy. Venous thrombosis was diagnosed in patients and confirmed to be absent in controls using duplex Doppler when phlebography findings were unconvincing. To eliminate possible false negatives (poor sensitivity of duplex Doppler in asymptomatic patients), all controls were contacted by telephone 3 to 6 months after discharge to ascertain whether or not they had been rehospitalized and if so for what reason. The patients and controls responded to questions designed to identify risk factors for deep-vein thrombosis described in the literature (patient characteristics, personal and family history, surgical history, associated diseases, abnormal blood tests, medical treatment, life style). RESULTS: The three main risk factors for deep-vein thrombosis for all ages and both sexes identified by multivariate analysis were: personal history of venous thrombosis (OR = 4.7, 95% CI = [2.4; 8.9]), family history of venous thrombosis (OR = 3.3, 95% CI [1.8; 5.9]) and surgical during the preceding 45 days (OR = 3.7, 95% CI = [1.2; 10.9]). In non-menopaused women, the main risk factor was minidose oral contraception (OR = 6.9, 95% CI = [1.9; 25.4]). CONCLUSION: In our population of hospitalized patients in an internal medicine unit, the main risk factor for thrombosis appeared to be, in general, a past history of venous thrombosis and in non-menopaused women, minidose oral contraception.

Adult↗
PubMed1996

Solubilization and characterization of a thyroid Ca(2+)-dependent and NADPH-dependent K3Fe(CN)6 reductase. Relationship with the NADPH-dependent H2O2-generating system.

The thyroid plasma membrane contains a Ca(2+)-regulated NADPH-dependent H2O2-generating system which provides H2O2 for the thyroid-peroxidase-catalyzed biosynthesis of thyroid hormones. The molecular nature of the membrane-associated electron transport chain that generates H2O2 in the thyroid is unknown, but recent observations indicate that a flavoprotein containing a FAD prosthetic group is involved. Solubilization was reinvestigated using 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (Chaps), Triton X-100, and high salt concentrations. Chaps eliminated about 30% of the proteins, which included a ferricyanide reductase, without affecting the H2O2-generating system. Similarly, Triton X-100 alone did not extract the NADPH oxidase. An NADPH-oxidase activity, which was measured in the presence of the artificial electron acceptor potassium ferricyanide, was solubilized by increasing the ionic strength to 2 M KCl. This NADPH-ferricyanide reductase activity was shown to belong to the H2O2-generating system, although it did not produce H2O2. It was still Ca2+ dependent and H2O2 production was restored by decreasing the ionic strength by overnight dialysis. No H2O2 production activity was detected after sucrose density gradient centrifugation of the dialyzed solubilized enzyme, but a well-defined peak of NADPH oxidation activity with a sedimentation coefficient of 3.71 S was found in the presence of K3Fe(CN)6. These results suggest that some unknown component(s) (phospholipid or protein) is removed during sucrose density gradient centrifugation. Finally, thyrotropin, which induces NADPH oxidase and regulates H2O2 production in porcine thyrocytes in primary culture, also induced the NADPH-K3Fe(CN)6 reductase activity associated with the H2O2-generating system. Thus, this enzyme seems to be another marker of thyroid differentiation.

Animals↗
PubMed1996

Production of human papillomavirus type 45 virus-like particles in insect cells using a recombinant baculovirus.

The L1 major capsid protein of human papillomavirus type 45 was expressed in insect cells using recombinant baculovirus technology. Human papillomavirus type 45 L1 major capsid protein self-assembled into empty virus-like particles (VLPs). These 50-60 nm diameter particles were present in the nuclei of recombinant baculovirus-infected insect cells and had a density of 1.29 - 1.30 g/cm3 in cesium chloride. The expressed human papillomavirus type 45 L1 protein sequence is identical to the reference human papillomavirus type 45 strain except for one amino acid located at position 49 of the human papillomavirus type 45 L1 protein. It must be noted that the quantity of purified human papillomavirus type 45 virus-like particles is at a lower level than that previously observed with human papillomavirus type 16. Nevertheless, the ability to generate preparative amounts of human papillomavirus type 45 virus-like particles is of great importance for the production of an anti-human papillomavirus vaccine.

Animals↗
PubMed1996

Identification of different galectins by immunoblotting after two-dimensional polyacrylamide get electrophoresis with immobilized pH gradients.

Vertebrate soluble beta-galactoside-binding lectins form a growing protein family that recently have been named galectins. Seven different galectins have been sequenced and characterized in mammals, and there is compelling evidence for the existence of other members of this lectin family. Three among six galectins are homodimers with (i) an identical subunit of a relative molecular mass of about 14500, and (ii) amino acid sequence homologies giving rise to possible immunochemical cross-reactivities. They are indistinguishable from each other by conventional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), even when followed by immunoblotting. However, their different isoelectric points allow their identification using isoelectric focusing and two-dimensional (2-D) polyacrylamide gel electrophoresis. A strategy was developed to identify these galectins in crude extracts from cells and tissues, based on the two-dimensional electrophoresis with immobilized pH gradient (IPG-Dalt) analysis of the specific spots of purified galectins and of the spots of crude extracts, after silver staining. In addition, 2-D immunoblotting using anti-galectin 1 (Gal-1) and anti carbohydrate-binding protein 15 (CPB15) antibodies were performed on brain and leukemia cells (HL60) allowing an identification of related polypeptides. Our results indicate that the use of IPG-Dalt provides a suitable reproducibility and allows the detection of galectins or other galactoside-binding proteins even at basic pIs.

Brain Chemistry↗
PubMed1996

The Ca2+- and reduced nicotinamide adenine dinucleotide phosphate-dependent hydrogen peroxide generating system is induced by thyrotropin in porcine thyroid cells.

Hydrogen peroxide (H2O2) is an essential electron acceptor for thyroid peroxidase-catalyzed iodination and coupling reactions. In the presence of iodide, its production is a limiting step in thyroid hormone biosynthesis. Several studies have demonstrated that the thyroid particulate fraction contains a Ca2+- and NADPH- dependent H@O@ generator (NADPH-O2:oxidoreductase), the so- called thyroid NADPH-oxidase. It has recently been demonstrated that cellular H2O2 release is under the tonic control of TSH in primary cultures of dog thyrocytes. The present study evaluates the effect of TSH on the thyroid NADPH-oxidase and cytochrome c reductase activities, two enzymes believed to be involved on H2O2 generation in the thyroid gland. There was almost no detectable NADPH-dependent H2O2 generator in the membranes of cells grown for 18 h without TSH. But cells grown in the presence of TSH (0.1 mU/ml) had a CA2+- and NADPH-dependent H2O2-generating activity that increased up to the third day in culture, as did the cell iodide organification capacity. This increase was also partially blocked by 12-O-tetradecanoylphorbol 13-acetate and cycloheximide. Forskolin and 8-bromo-cAMP both reproduced the action of TSH on the Ca2+- and NADPH-dependent H2O2 generator. In contrast, the thyroid NADPH-cytochrome c reductase activity in particles from control cells was similar to that of TSH-treated cells and was unaffected by forskolin or 12-O-tetradecanoylphorbol 13-acetate. These results suggest that NADPH-cytochrome c reductase activity is not regulated by TSH and, thus, reinforce the idea that this enzyme is not involved in thyroid H2O2 generation. On the other hand, the Ca2+- and NADPH-dependent H2O2 generator, so-called thyroid NADPH- oxidase, is induced by TSH through the cAMP cascade. Thus, it seems to be another marker of thyroid differentiation, in addition to thyroperoxidase and thyroglobulin, and could play a key role in thyroid hormone production.

Animals↗
PubMed1996

[An unjustified fear].

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Acquired Immunodeficiency Syndrome↗