Impact de la localisation de la CaM Kinase II sur la plasticité synaptique

La plasticité synaptique représente un mécanisme fondamental de l'apprentissage et de la mémoire au cours du développement et durant la vie adulte. Au niveau moléculaire, il est connu que la CaMKII joue un rôle important dans la plasticité et la maturation des synapses. L'objectif était de démontrer par mesure électrophysiologique que la translocalisation de la CaMKII à la synapse est nécessaire à la potentialisation à long terme (LTP) des courants synaptiques. Pour tester cette hypothèse, une étape critique devait d'abord être franchie, celle d'établir une méthode robuste pour induire de la LTP dans des neurones d'hippocampe de rat maintenus en culture, où on peut manipuler l'expression et la dynamique spatiale de la CaMKII. Ce mémoire montre que cette première étape n ' a pu être établie et qu'ainsi l'hypothèse de départ n'a pu être testée. Néanmoins, je présente une méthode candidate prometteuse, faisant appel à une lumière intense, pour augmenter la fréquence des événements synaptiques. De plus, j ' a i développé un outil qui permettra bientôt d'automatiser les mesures d'électrophysiologie et microscopie nécessaires pour tester l'hypothèse de départ. Il devrait entre autre accélérer notre capacité de trouver un protocole optimal pour induire de la LTP en culture en testant un plus grand nombre de conditions expérimentales de manière rapide et reproductible

Morphology-based cerebrovascular atlas

International audienceCerebrovascular atlases can be used to improve medical tasks requiring the analysis of 3D angiographic data. The generation of such atlases remains however a complex and infrequently considered issue. The existing approaches rely on information exclusively related to the vessels. We alternatively investigate a new way, consisting of using both vascular and morphological information (i.e., cerebral structures) to improve the accuracy and relevance of the obtained vascular atlases. Experiments emphasise improvements in the main steps of the atlas generation process impacted by the use of morphological information. An example of cerebrovascular atlas obtained from a dataset of 56 MRAs acquired from several acquisition devices is finally provided

Turbulence-airfoil interaction noise reduction using wavy leading edge: an experimental and numerical study

International audiencePassive treatments aiming at reducing turbofan broadband noise have been recently studied in the framework of European Project FLOCON. A concept based on a sinusoidal variation of the leading edge of a single airfoil aiming at reducing interaction noise has been investigated by ONERA. Turbulence-airfoil interaction mechanism is achieved using a turbulence grid located upstream of a NACA airfoil tested in ISVR anechoic open wind tunnel. High noise reductions are obtained (3-4 dB) for all studied flow speeds. Moreover, aerodynamic performances are shown to be slightly increased by the treatment that tends to reduce the drag without modify the mean loading. Experimental work is supplemented by numerical simulations using Large Eddy Simulations (LES) and direct Euler approaches to predict the acoustic response of the wing. LES is chained to a FWH (Ffowcs-Williams and Hawkings) integral to assess the radiated field. Isentropic turbulence is synthetically injected by means of a suited inflow boundary condition. Present computations are focused on the reference case (without treatment). Numerical predictions are compared to the experiment, and to analytical solutions issued from Amiet theory

Adaptive Movement Compensation for In Vivo Imaging of Fast Cellular Dynamics within a Moving Tissue

In vivo non-linear optical microscopy has been essential to advance our knowledge of how intact biological systems work. It has been particularly enabling to decipher fast spatiotemporal cellular dynamics in neural networks. The power of the technique stems from its optical sectioning capability that in turn also limits its application to essentially immobile tissue. Only tissue not affected by movement or in which movement can be physically constrained can be imaged fast enough to conduct functional studies at high temporal resolution. Here, we show dynamic two-photon Ca2+ imaging in the spinal cord of a living rat at millisecond time scale, free of motion artifacts using an optical stabilization system. We describe a fast, non-contact adaptive movement compensation approach, applicable to rough and weakly reflective surfaces, allowing real-time functional imaging from intrinsically moving tissue in live animals. The strategy involves enslaving the position of the microscope objective to that of the tissue surface in real-time through optical monitoring and a closed feedback loop. The performance of the system allows for efficient image locking even in conditions of random or irregular movements

Prognostic impact of Epstein-Barr virus serostatus in patients with nonmalignant hematological disorders undergoing allogeneic hematopoietic cell transplantation: the study of Infectious Diseases Working Party of the European Society for Blood and Marrow Transplantation

BackgroundIn patients with acute leukemia, lymphoma and chronic malignancies, donor and/or recipient Epstein-Barr virus (EBV) seropositive status increases the risk of development of chronic graft-versus-host disease (cGVHD) after allo-hematopoietic cell transplantation (allo-HCT), while it has no influence on other transplant outcomes. No data are available on the impact of EBV serostatus on transplant outcomes in patients with nonmalignant hematological disorders. ObjectiveWe analyzed the influence of the recipient's (R) and donor's (D) EBV serostatus on transplant outcomes (overall survival (OS); relapse-free survival (RFS); relapse incidence (RI); nonrelapse mortality (NRM); acute graft-versus-host disease (aGVHD); cGVHD) in patients with nonmalignant hematological disorders undergoing allo-HCT. Patients and MethodsA total of 2,355 allo-HCTs performed between 1997 and 2016 for acquired bone marrow failure or hemoglobinopathies were included in this retrospective Registry megafile Infectious Diseases Working Party of the European Society of Blood and Marrow Transplantation (IDWP-EBMT) study. ResultsArray ConclusionsAllo-HCT from EBV-seropositive versus EBV-seronegative donors are at 31% higher risk of cGVHD in patients with nonmalignant hematological disorders undergoing allo-HCT; however this difference is nonsignificant in multivariate analysis

Stem cell transplantation for congenital dyserythropoietic anemia : an analysis from the European Society for Blood and Marrow Transplantation

Non peer reviewe

Recalage d'images par association de primitives, construction et analyse d'histogrammes multidimensionnels

Nous présentons une technique de recalage d'images mise au point dans le cadre de l'analyse de séquences d'images infrarouge. Nous nous sommes limités au cas où la transformation recherchée est la composée d'une rotation et d'une translation. L'extension de la complexité de la transformation est cependant tout à fait envisageable. La technique proposée est basée sur une analyse statistique de déplacements élémentaires. Dans un premier temps, nous abordons la détermination des déplacements élémentaires, réalisée par une mise en correspondance de listes de primitives extraites des deux images. Nous avons défini dans ce cadre un nouvel opérateur permettant de caractériser et de localiser ponctuellement les coins et les régions de petite taille dans une image. Ensuite nous présentons l'algorithme que nous avons conçu pour l'estimation des paramètres de la transformation. Enfin nous présentons les résultats obtenus sur des images infrarouges de scènes filmées en air-sol et en sol-sol

Hot DQ White Dwarf Stars: A New Challenge to Stellar Evolution

We report the discovery of a new class of hydrogen-deficient stars: white dwarfs with an atmosphere primarily composed of carbon, with little or no trace of hydrogen or helium. Our analysis shows that the atmospheric parameters found for these stars do not fit satisfactorily in any of the currently known theories of post-asymptotic giant branch (AGB) evolution, although these objects might be the cooler counter-part of the unique and extensively studied PG 1159 star H1504+65. These stars, together with H1504+65, might thus form a new evolutionary post-AGB sequence.Proceedings of conference on "Hydrogen-Deficient Stars", held 17-21 September, 2007 at Eberhard Karls University, Tübingen (Germany). Edited by Klaus Werner and Thomas Rauch.info:eu-repo/semantics/publishe

A statistical arteriovenous cerebral atlas

International audienceIn this paper, we propose a pipeline for building statistical cerebro-vascular atlases from 3D angiographic datasets. This pipeline relies on recent advances in vessel segmentation and filtering, image skeletonization, and image registration. The generated atlases embed information on vesselness probability , vein/artery discrimination, vessel size and relative orientation. It improves on previously proposed approaches. Experiments performed on a dataset of 54 MRA/MRI images allowed us to propose an original vascular atlas of the whole intracranial volume