The TGF-β/Smad Repressor TG-Interacting Factor 1 (TGIF1) Plays a Role in Radiation-Induced Intestinal Injury Independently of a Smad Signaling Pathway

Despite advances in radiation delivery protocols, exposure of normal tissues during the course of radiation therapy remains a limiting factor of cancer treatment. If the canonical TGF-β/Smad pathway has been extensively studied and implicated in the development of radiation damage in various organs, the precise modalities of its activation following radiation exposure remain elusive. In the present study, we hypothesized that TGF-β1 signaling and target genes expression may depend on radiation-induced modifications in Smad transcriptional co-repressors/inhibitors expressions (TGIF1, SnoN, Ski and Smad7). In endothelial cells (HUVECs) and in a model of experimental radiation enteropathy in mice, radiation exposure increases expression of TGF-β/Smad pathway and of its target gene PAI-1, together with the overexpression of Smad co-repressor TGIF1. In mice, TGIF1 deficiency is not associated with changes in the expression of radiation-induced TGF-β pathway-related transcripts following localized small intestinal irradiation. In HUVECs, TGIF1 overexpression or silencing has no influence either on the radiation-induced Smad activation or the Smad3-dependent PAI-1 overexpression. However, TGIF1 genetic deficiency sensitizes mice to radiation-induced intestinal damage after total body or localized small intestinal radiation exposure, demonstrating that TGIF1 plays a role in radiation-induced intestinal injury. In conclusion, the TGF-β/Smad co-repressor TGIF1 plays a role in radiation-induced normal tissue damage by a Smad-independent mechanism

Sensitivity and dose dependency of radiation-induced injury in hematopoietic stem/progenitor cells in mice

We evaluated the sensitivity and dose dependency of radiation-induced injury in hematopoietic stem/progenitor cells. Adult C57BL/6 mice were daily exposed to 0, 2, 10, 50, and 250 mGy γ-ray for 1 month in succession, respectively. The damage of hematopoietic stem/progenitor cells in bone marrow were investigated within 2 hours (acute phase) or at 3 months (chronic phase) after the last exposure. Daily exposure to over 10 mGy γ-ray significantly decreased the number and colony-forming capacity of hematopoietic stem/progenitor cells at acute phase, and did not completely recover at chronic phase with 250 mGy exposure. Interestingly, the daily exposure to 10 or 50 mGy γ-ray decreased the formation of mixed types of colonies at chronic phase, but the total number of colonies was comparable to control. Immunostaining analysis showed that the formation of 53BP1 foci in c-kit + stem/progenitor cells was significantly increased with daily exposure to 50 and 250 mGy at acute phase, and 250 mGy at chronic phase. Many genes involved in toxicity responses were up- or down-regulated with the exposures to all doses. Our data have clearly shown the sensitivity and dose dependency of radiation-induced injury in hematopoietic stem/progenitor cells of mice with daily exposures to 2 ? 250 mGy γ-ray

Contribution à l'étude des capteurs magnétiques à induction pour la prospection magnéto-tellurique étude de la sensibilité et améliorations

L'enregistrement des variations du champ magnétique terrestre demande des capteurs aux performances de plus en plus élevées. Le but de la première partie de cet exposé consiste à définir à partir du phénomène la sensibilité nécessaire à un bon enregistrement et à voir comment on peut améliorer cette sensibilité d'une façon générale. Dans la seconde partie, on développe un des moyens d'augmenter cette sensibilité ainsi qu'une modification permettant d'alléger le noyau

Sondage magnétotellurique sur le massif granitique de Mortagne-sur-Sèvre

National audienc

Étude du toit de la nappe de Beauce à Villamblain par résistivité électrique

International audienceWater resources control is one of the main environmental problems al this ending twentielh century. Piezometrie surface knowledge of the water table of the Beauce region is crucial to estimate the water reserve in this intensive-farming region. To this end, some electrical soundings with a Schlumberger array and a dipôle-dipôle multi-electrode melhod were tested on the Villamblain study domain. The water table, corresponding to an electrical conductive medium, is detected. However it is difficult to clearly separate the eleclrical conductivity effect of the water table from that of the Gâtinais molasse, which is a clayey conduclive layer present within the aquifer. The pedological cover and the geological substratum are clearly individualised with the multi-electrode method, which confirms its interest

Étude du toit de la nappe de Beauce à Villamblain par résistivité électrique

International audienceWater resources control is one of the main environmental problems al this ending twentielh century. Piezometrie surface knowledge of the water table of the Beauce region is crucial to estimate the water reserve in this intensive-farming region. To this end, some electrical soundings with a Schlumberger array and a dipôle-dipôle multi-electrode melhod were tested on the Villamblain study domain. The water table, corresponding to an electrical conductive medium, is detected. However it is difficult to clearly separate the eleclrical conductivity effect of the water table from that of the Gâtinais molasse, which is a clayey conduclive layer present within the aquifer. The pedological cover and the geological substratum are clearly individualised with the multi-electrode method, which confirms its interest