58 research outputs found

    Helicobacter pullorum cytolethal distending toxin targets vinculin and cortactin and triggers formation of lamellipodia in intestinal epithelial cells

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    Helicobacter pullorum, a bacterium initially isolated from poultry, has been associated with human digestive disorders. However, the factor responsible for its cytopathogenic effects on epithelial cells has not been formally identified. The cytopathogenic alterations induced by several human and avian H. pullorum strains were investigated on human intestinal epithelial cell lines. Moreover, the effects of the cytolethal distending toxin (CDT) were evaluated first by using a wild-type strain and its corresponding cdtB isogenic mutant and second by delivering the active CdtB subunit of the CDT directly into the cells. All of the H. pullorum strains induced cellular distending phenotype, actin cytoskeleton remodeling, and G2/M cell cycle arrest. These effects were dependent on the CDT, as they were (1) not observed in response to a cdtB isogenic mutant strain and (2) present in cells expressing CdtB. CdtB also induced an atypical delocalization of vinculin from focal adhesions to the perinuclear region, formation of cortical actin-rich large lamellipodia with an upregulation of cortactin, and decreased cellular adherence. In conclusion, the CDT of H. pullorum is responsible for major cytopathogenic effects in vitro, confirming its role as a main virulence factor of this emerging human pathogen.This work was supported by the Institut national de la santĂ© et de la recherche mĂ©dicale, the University Bordeaux Segalen, the Conseil RĂ©gional d’Aquitaine (grants 20030304002FA and 20040305003 FA), the SociĂ©tĂ© Nationale Française de GastroentĂ©rologie, the European Union (FEDER no. 2003227

    Regards sur l'archéologie dans la Loire: Journées d'études tenues les 6 et 7 novembre 2009 au Musée Déchelette de Roanne. Histoire et Patrimoine de Roanne et sa région, n°17

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    Numéro spécial : parution des communications des Journées d'études tenues les 6 et 7 novembre 2009 au Musée Déchelette de Roanne à l'occasion du 50Úme anniversaire du Groupe de recherches archéologiques du Roannais

    Dispersion improvement of carbon nanotubes in epoxy resin using amphiphilic block copolymers

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    International audienceInterface between Carbon NanoTubes (CNT) and epoxy matrix is admitted to play an important role in the dispersion quality and in the mechanical stress transfer. To improve the interfacial adhesion, we propose to chemically graft molecules onto CNT surface. To achieve this chemical modification, a controlled radical polymerization, named Nitroxide Mediated Polymerization NMP, is used to synthesize a diblock copolymer based on Acrylic Acid (PAA block) and Methyl MethAcrylate (PMMA block). In the present paper, this polymerization is performed "in situ ". The PAA block presents a good affinity with the CNT which enable grafting. The PMMA miscibility with epoxy is expected to give a good adhesion-between the CNT and the matrix-and to bring a better dispersion. In order to compare the chemical modification and the physical adsorption of the copolymers onto CNT dispersion, the same block copolymer was synthesized with and without CNT. The copolymer synthesis was controlled and characterized by different methods as NMR 1H (conversion and composition), SEC (molecular weight) and TGA (grafting density). We show that the better dispersion quality and better physical properties have been obtained with grafted CNT
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