Vitamin D Receptor Controls Cell Stemness in Acute Myeloid Leukemia and in Normal Bone Marrow.

Vitamin D (VD) is a known differentiating agent, but the role of VD receptor (VDR) is still incompletely described in acute myeloid leukemia (AML), whose treatment is based mostly on antimitotic chemotherapy. Here, we present an unexpected role of VDR in normal hematopoiesis and in leukemogenesis. Limited VDR expression is associated with impaired myeloid progenitor differentiation and is a new prognostic factor in AML. In mice, the lack of Vdr results in increased numbers of hematopoietic and leukemia stem cells and quiescent hematopoietic stem cells. In addition, malignant transformation of Vdr-/- cells results in myeloid differentiation block and increases self-renewal. Vdr promoter is methylated in AML as in CD34+ cells, and demethylating agents induce VDR expression. Association of VDR agonists with hypomethylating agents promotes leukemia stem cell exhaustion and decreases tumor burden in AML mouse models. Thus, Vdr functions as a regulator of stem cell homeostasis and leukemic propagation

Les politiques de la quantification

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Travaux de l’École française d’Athènes en 2014-2015. La prospection de l’Anavlochos I

Le programme d’exploration de l’Anavlochos vise à caractériser l’occupation ancienne du massif en se fondant sur une étude de sa géomorphologie, de sa topographie et des vestiges archéologiques (structures architecturales et mobilier) observables en surface . La première partie de la prospection du massif, programmée sur deux ans (2015-2016), a été conduite du 27 juillet au 23 août 2015. La dernière semaine de la campagne, du 24 au 28 août, a été consacrée au lavage et à l’étude préliminaire du matériel collecté sur le terrain. Les efforts se sont concentrés dans le vallon central du massif, où s’étend l’habitat géométrique, sur le sommet Ouest et sur la pente Nord de Kako Plaï (fig. 1). Au total, environ 30 ha ont été prospectés de manière intensive et plus de 300 structures architecturales antiques (murs de terrasse, murs externes et internes d’édifices, rampes d’accès, aménagements hydrauliques) ont été relevées, cartographiées, décrites et photographiées de manière systématique. Environ 35 ha, situés en contrebas de l’habitat et nettement moins densément occupés, ont en outre été parcourus de manière extensive. Pour des raisons de sécurité, on a dû renoncer à prospecter certaines zones particulièrement escarpées (falaises et pentes abruptes). Dans les espaces recouverts d’un tapis épineux trop épais, le manque de visibilité a enfin entravé les investigations. Le mobilier archéologique visible en surface a été quantifié, mais seuls les fragments de céramique fine et les fragments remarquables (formes, tessons décorés, pâtes inusuelles) de céramique grossière ont été collectés, par unité de prospection (UP) d’1 ha, en suivant la ligne des terrasses. La proportion de matériel retenu a été évaluée et sera prise en compte dans l’étude finale. Dans le secteur circonscrit du dépôt votif (Kako Plaï), le matériel observable en surface a en revanche été ramassé de manière exhaustive. Au total, environ 100 kg de matériel archéologique ont été collectés cette année, puis traités et entreposés au Musée d’Agios Nikolaos. Au sein des différentes UP prospectées, le mobilier associé à des structures architecturales remarquables ou présentant une concentration significative a été isolé. Dans chaque UP, la géomorphologie, la topographie, le couvert végétal et les perturbations liées à l’activité humaine moderne ont été documentés de manière précise et systématique

Chemical degassing on EDF units - Feed back experience and method

International audienceThe chemical degassing feasibility of all French units RCS during outages is usually performed on the four 1500 MWe French units since July 2004 and is planned for 2007 on the 34 units of 900 MWe and the 20 units of 1300 MWe units. It helps to an optimized shutdown planning management, especially in case of unplanned shutdowns, and helps to limit the thermal stress corrosion of RHR at temperature higher than 120°C by avoiding temperature step extension after bubble collapsing to remove hydrogen increase. Chemical degassing is performed at temperature equal or lower than 80°C, by hydrogen peroxide injection if 3 < H2dissolved < 35 cm3/kg. H2O2 calculation can be stoechiometric or increased by 20 % depending on the SG tubes material and the full power operation duration before the shutdown. Purification flow is adapted to each design type units characteristics to easily manage a hypothetical early oxygenation. Early oxygenation management consists in forecasting the dilution of the VCT (Volume Control Tank) gaseous phase by nitrogen to avoid dangerous H2 /O2 gaseous mixture and to obtain oxygenation criteria on VCT. Three kinds of dilution can be used: nitrogen burping with high levels amplitude, continuous nitrogen flushing or discontinuous flushing with a maximal constant VCT level but pressure variation

Prospection de l’Anavlochos I

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Prospection de l’Anavlochos I

Enjeux et méthodes de la prospection Le programme d’exploration de l’Anavlochos vise à caractériser l’occupation ancienne du massif en se fondant sur une étude de sa géomorphologie, de sa topographie et des vestiges archéologiques (structures architecturales et mobilier) observables en surface. La première partie de la prospection du massif, programmée sur deux ans (2015‑2016), a été conduite du 27 juillet au 23 août 2015. La dernière semaine de la campagne, du 24 au 28 août, a été consacrée ..

Low primary system contamination levels in some French PWRs

International audiencePWRs equipped with Steam Generator tubing in a nickel-based alloy (alloy 600 or 690) are generally characterized by higher Co-58 peaks during cold shutdowns (order of magnitude of 100 GBq/m3) and higher Co-58 deposited activities (several GBq/m²) compared to PWRs equipped with SG tubing in an iron-based alloy (alloy 800 or stainless steel). However, the trends are different for the Steam Generator Replacement (SGR) with alloy 690 carried out in the last decade, in particular for the SAINT-LAURENT-B1 PWR: after an increase in the Co-58 contamination just after the SGR, the contamination on the primary system decreases and reaches a very low level several cycles after the SGR. The Co-58 peak during cold shutdowns follows the same variation, it drops by a factor of 10 to 100. Similar levels are also measured in the last French operating PWR generation (N4). The key factor of these low Co-58 deposited and released activities is the surface finish of alloy 690TT SG tubing by means of an improved manufacturing process. The nickel release is low enough to limit the presence of metallic nickel or nickel oxide, which tend to form deposits on fuel elements. In consequence, nickel deposits on fuel elements and then 58Co volume and surface activities are reduced

Status of primary system Contamination in French PWRs

International audienceThe reduction of collective dose is an important objective for all nuclear plant operators. Since the beginning of French PWR commissioning, the French strategy has been to study the impact of design and operating parameters. With the codes and the test loops, the third support to these studies is the measurement campaigns of contamination in PWRs.Since 1971, the deposited activities in PWR primary systems have been measured by gamma spectrometry, deposited activities providing more information than dose rates. These gamma spectrometry measurements with the EMECC system represent about 250 measurement campaigns in France and abroad. This paper presents the status of primary system contamination in French PWRs and some of the main lessons learnt from the EMECC campaign analyses.The primary system 60Co contamination in French PWRs has a tendency to increase for several cycles and then to be constant or even to decrease, whereas 58Co contamination tends to decrease on primary coolant piping and to slightly increase on SG tubing. Thanks to the improvements of French PWR design and operation (pH300°C of 7.2, Zry spacer grids, 690TT Steam generator tubing with a low cobalt content…), the dose rate indices tend to decrease with PWR generations and operating cycles