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Search Results: 1 - 10 of 10112 matches for " Ga?tan Chicanne "
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Phosphatase-Dead Myotubularin Ameliorates X-Linked Centronuclear Myopathy Phenotypes in Mice
Leonela Amoasii equal contributor,Dimitri L. Bertazzi equal contributor,Hélène Tronchère,Karim Hnia,Gatan Chicanne,Bruno Rinaldi,Belinda S. Cowling,Arnaud Ferry,Bruno Klaholz,Bernard Payrastre ? ,Jocelyn Laporte ? ,Sylvie Friant ?
PLOS Genetics , 2012, DOI: 10.1371/journal.pgen.1002965
Abstract: Myotubularin MTM1 is a phosphoinositide (PPIn) 3-phosphatase mutated in X-linked centronuclear myopathy (XLCNM; myotubular myopathy). We investigated the involvement of MTM1 enzymatic activity on XLCNM phenotypes. Exogenous expression of human MTM1 in yeast resulted in vacuolar enlargement, as a consequence of its phosphatase activity. Expression of mutants from patients with different clinical progression and determination of PtdIns3P and PtdIns5P cellular levels confirmed the link between vacuolar morphology and MTM1 phosphatase activity, and showed that some disease mutants retain phosphatase activity. Viral gene transfer of phosphatase-dead myotubularin mutants (MTM1C375S and MTM1S376N) significantly improved most histological signs of XLCNM displayed by a Mtm1-null mouse, at similar levels as wild-type MTM1. Moreover, the MTM1C375S mutant improved muscle performance and restored the localization of nuclei, triad alignment, and the desmin intermediate filament network, while it did not normalize PtdIns3P levels, supporting phosphatase-independent roles of MTM1 in maintaining normal muscle performance and organelle positioning in skeletal muscle. Among the different XLCNM signs investigated, we identified only triad shape and fiber size distribution as being partially dependent on MTM1 phosphatase activity. In conclusion, this work uncovers MTM1 roles in the structural organization of muscle fibers that are independent of its enzymatic activity. This underlines that removal of enzymes should be used with care to conclude on the physiological importance of their activity.
Genetic Interaction between MTMR2 and FIG4 Phospholipid Phosphatases Involved in Charcot-Marie-Tooth Neuropathies
Ilaria Vaccari,Giorgia Dina,Hélène Tronchère,Emily Kaufman,Gatan Chicanne,Federica Cerri,Lawrence Wrabetz,Bernard Payrastre,Angelo Quattrini,Lois S. Weisman,Miriam H. Meisler,Alessandra Bolino
PLOS Genetics , 2011, DOI: 10.1371/journal.pgen.1002319
Abstract: We previously reported that autosomal recessive demyelinating Charcot-Marie-Tooth (CMT) type 4B1 neuropathy with myelin outfoldings is caused by loss of MTMR2 (Myotubularin-related 2) in humans, and we created a faithful mouse model of the disease. MTMR2 dephosphorylates both PtdIns3P and PtdIns(3,5)P2, thereby regulating membrane trafficking. However, the function of MTMR2 and the role of the MTMR2 phospholipid phosphatase activity in vivo in the nerve still remain to be assessed. Mutations in FIG4 are associated with CMT4J neuropathy characterized by both axonal and myelin damage in peripheral nerve. Loss of Fig4 function in the plt (pale tremor) mouse produces spongiform degeneration of the brain and peripheral neuropathy. Since FIG4 has a role in generation of PtdIns(3,5)P2 and MTMR2 catalyzes its dephosphorylation, these two phosphatases might be expected to have opposite effects in the control of PtdIns(3,5)P2 homeostasis and their mutations might have compensatory effects in vivo. To explore the role of the MTMR2 phospholipid phosphatase activity in vivo, we generated and characterized the Mtmr2/Fig4 double null mutant mice. Here we provide strong evidence that Mtmr2 and Fig4 functionally interact in both Schwann cells and neurons, and we reveal for the first time a role of Mtmr2 in neurons in vivo. Our results also suggest that imbalance of PtdIns(3,5)P2 is at the basis of altered longitudinal myelin growth and of myelin outfolding formation. Reduction of Fig4 by null heterozygosity and downregulation of PIKfyve both rescue Mtmr2-null myelin outfoldings in vivo and in vitro.
Phosphatidylinositol 3-Monophosphate Is Involved in Toxoplasma Apicoplast Biogenesis
Lina Tawk,Jean-Fran?ois Dubremetz,Philippe Montcourrier,Gatan Chicanne,Fabrice Merezegue,Véronique Richard,Bernard Payrastre,Markus Meissner,Henri J. Vial,Christian Roy,Kai Wengelnik equal contributor ,Maryse Lebrun equal contributor
PLOS Pathogens , 2011, DOI: 10.1371/journal.ppat.1001286
Abstract: Apicomplexan parasites cause devastating diseases including malaria and toxoplasmosis. They harbour a plastid-like, non-photosynthetic organelle of algal origin, the apicoplast, which fulfils critical functions for parasite survival. Because of its essential and original metabolic pathways, the apicoplast has become a target for the development of new anti-apicomplexan drugs. Here we show that the lipid phosphatidylinositol 3-monophosphate (PI3P) is involved in apicoplast biogenesis in Toxoplasma gondii. In yeast and mammalian cells, PI3P is concentrated on early endosomes and regulates trafficking of endosomal compartments. Imaging of PI3P in T. gondii showed that the lipid was associated with the apicoplast and apicoplast protein-shuttling vesicles. Interference with regular PI3P function by over-expression of a PI3P specific binding module in the parasite led to the accumulation of vesicles containing apicoplast peripheral membrane proteins around the apicoplast and, ultimately, to the loss of the organelle. Accordingly, inhibition of the PI3P-synthesising kinase interfered with apicoplast biogenesis. These findings point to an unexpected implication for this ubiquitous lipid and open new perspectives on how nuclear encoded proteins traffic to the apicoplast. This study also highlights the possibility of developing specific pharmacological inhibitors of the parasite PI3-kinase as novel anti-apicomplexan drugs.
Grounding the Human Body Improves Facial Blood Flow Regulation: Results of a Randomized, Placebo Controlled Pilot Study  [PDF]
Gaétan Chevalier
Journal of Cosmetics, Dermatological Sciences and Applications (JCDSA) , 2014, DOI: 10.4236/jcdsa.2014.45039
Abstract:

Earthing (grounding) refers to bringing the human body in direct contact with the negative electric charge of the earth’s surface by barefoot exposure outdoors or using special conductive indoor systems that are connected to the Earth. To determine if earthing improves facial blood circulation/flow, a double-blind study was designed with forty subjects either grounded or sham-grounded (27 grounded subjects and 13 sham-grounded subjects acting as controls) for at least one hour in a comfortable recliner chair equipped with conductive mat, pillow, and patches. The grounding systems were either grounded or sham-grounded via a wire to the ground port (third hole) of a power outlet. A Laser Speckle Contrast Imaging camera was used to continuously record changes in facial blood flow non-invasively. Facial blood flow regulation clearly improved among grounded— but not sham-grounded—subjects. The results demonstrate, for the first time, that even one-hour contact with the earth restores blood flow regulation to the face suggesting enhanced skin tissue repair and improved facial appearance with possible implications for overall health. Further studies, using larger comparison groups, longer monitoring times, and more measuring methods, are warranted in order to confirm the novel influence of the Earth as a protector of skin health and appearance.

Grounding the Human Body during Yoga Exercise with a Grounded Yoga Mat Reduces Blood Viscosity  [PDF]
Richard Brown, Gaétan Chevalier
Open Journal of Preventive Medicine (OJPM) , 2015, DOI: 10.4236/ojpm.2015.54019
Abstract: Objective: Research continues to show that being connected to the earth can increase the potential of the body to scavenge free radicals. This study examined the effect of just one hour of grounding on blood viscosity while subjects participated in gentle yoga exercises designed to initiate minor inflammation. Design: In this double blind model, twenty-eight (28) subjects met at the Bowerman Sports Medicine Clinic on the campus of the University of Oregon and were grounded to the earth via contact with a grounded yoga mat or were sham-grounded. Ten yoga exercises were repeated five times over a one-hour period. Blood was taken pre and post exercise and analyzed for blood viscosity using a scanning capillary viscometer. Results: Subjects connected to the earth significantly reduced their post exercise systolic blood viscosity (p = 0.03) and diastolic blood viscosity (p = 0.03). Conclusion: Grounding has the ability to affect exercise induced inflammation, thereby reducing blood viscosity.
One-Hour Contact with the Earth’s Surface (Grounding) Improves Inflammation and Blood Flow—A Randomized, Double-Blind, Pilot Study  [PDF]
Gaétan Chevalier, Gregory Melvin, Tiffany Barsotti
Health (Health) , 2015, DOI: 10.4236/health.2015.78119
Abstract: Earthing (grounding) refers to the human body being in contact with the surface of the Earth by barefoot exposure outdoors or using special indoor systems connected to the Earth. Previous studies have showed multiple beneficial effects as a result of such contact, including better sleep, normalization of cortisol, reduced inflammation, pain and stress, and better blood flow. To determine if Earthing for one hour improves facial blood circulation, forty middle-aged volunteers were divided into a grounded group and a sham-grounded group according to a double-blind procedure. They were asked to sit in a comfortable recliner chair equipped with a grounding mat, pillow and patches. The grounding systems were either grounded or sham-grounded via a wire to the ground port of a power outlet. An infrared imaging camera was used to measure changes in blood flow and temperature. Thermal imaging showed clearly improved circulation of fluids (including blood) throughout the torso, which in turn, translates into enhanced delivery of blood to the head and improved blood circulation in the face as well. The results of this innovative study demonstrate that even one-hour contact with the Earth appears to promote significantly autonomic nervous system control of body fluids and peripheral blood flow that may improve blood circulation in the torso and face, facial tissue repair, skin health and vitality and optimize facial appearance (face anterior view p = 0.002; face lateral views p = 0.017; full anterior torso view p = 0.002). Further study using larger comparison groups and following subjects for a longer period of time (longitudinal study) is warranted.
Criatividade e pensamento crítico
Tremblay, Gatan;
Intercom: Revista Brasileira de Ciências da Comunica??o , 2011, DOI: 10.1590/S1809-58442011000100013
Abstract: in this short paper, based on an analysis of recent academic and political discourses on creativity, is develops a theoretical reflexion on the necessary dialectical articulation of creative and critical thinking in communication studies. in a first step, are questions the assumptions aiming to build a new social and economic paradigm based on creativity. it doubts, in particular, richard florida's theoretical and methodological hypotheses regarding the emergence of a creative class. in a second step, is showing how it is easy for politicians to promote creativity as a positive value making it a corner stone in the development of the information society. as a conclusion, it is showing that the renovation of critical thinking as a necessary complement of the promotion of creative process in communication studies.
Seeding Event: Creating and Developing Spaces of Entrepreneurial Freedom
Gatan Mourmant
Grounded Theory Review : an International Journal , 2012,
Abstract: This paper addresses the question of initiating, fostering and growing a vibrant economy by developing Spaces of Entrepreneurial Freedom (SoEF). Establishing and developing the SoEF is explained by a seeding event which is the core category of this grounded theory. In short, a seeding event leads to the patching of a potential, structural “hole”, which may prove valuable to an entrepreneurial network. Seeding events are started by an initiator who will recognize a network opportunity and exploit it. After event designing, the initiators implement the event through bold experimentation and using an adaptive structure. If the event is considered successful, the next stages are refining, growing, templating and finally replicating; these stages may occur one after the other or simultaneously. Through the development of SoEF, we suggest that entrepreneurs, governments, universities, large companies, and other players in the business world can improve the development of entrepreneurship at their respective levels.
Industries culturelles, économie créative et société de l’information
Gatan Tremblay
Global Media Journal : Canadian Edition , 2008,
Abstract: Après avoir rappelé les grandes lignes de la théorie des industries culturelles, l’auteur relie le “nouveau modèle” de l’économie créative aux diverses tentatives pour nommer et interpréter les changements qui affectent les sociétés industrialisées depuis la fin de la Seconde Guerre mondiale, de la société post-industrielle de Daniel Bell et d’Alain Touraine à la société de la connaissance de l’UNESCO. Il procède ensuite à l’examen critique des définitions et des évaluations des industries créatives. Il explique comment ces dernières reposent sur un usage et une interprétation de données statistiques fort contestables. Il discute les résultats surprenants, voire aberrants, auxquels en arrivent les auteurs du rapport de la Conférence des Nations Unies sur le Commerce et le Développement (CNUCED) dans leur tentative de mesurer la taille de l’économie créative sur l’ensemble de la planète. Enfin, il tente d’interpréter les motifs sous-jacents à la promotion de cette nouvelle version de l’idéologie de la société de l’information. Si les données disponibles montrent que l’art et la culture ne comptent que pour une valeur relativement faible des industries créatives, ils sont au c ur de l’opération idéologique. L’évocation de la créativité permet de jeter des ponts en direction des activités culturelles, dont l’intégration donne du lustre et de la légitimité à l’ensemble. Surtout, l’arrimage aux industries culturelles permet de se réclamer des mêmes spécificités économiques que l’analyse a permis de dégager au cours des quatre dernières décennies et de revendiquer la même protection, les mêmes interventions que les pouvoirs publics ont déployées au fil des ans dans les secteurs artistiques et culturels.
Quelques conditions pour une sémiotique de la cartographie
Gatan DESMARAIS
Mappemonde , 1986,
Abstract: La cartographie, satisfaisant aux cinq conditions empruntées à Hjelmslev et étudiées ici en détail pour rendre compte de sa structure, fonctionne bien comme un langage. On peut donc l'aborder selon les méthodes de la sémiologie.
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