6 research outputs found
Etude du rÎle de la PKC Zeta dans la rétinopathie diabétique
PARIS5-BU MĂ©d.Cochin (751142101) / SudocSudocFranceF
Etude du rÎle de la protéine QN1/KIAA1009, une nouvelle molécule motrice de la famille des kinésines, au cours de la prolifération et de la différenciation neuronale
Les molécules motrices telles que les kinésines sont impliquées dans divers processus fondamentaux comme la mitose, le transport vésiculaire, la transcription ou la réparation de l'ADN. Dans ce travail, nous montrons pour la premiÚre fois que la protéine QN1 appartient à la famille des kinésines et a pour orthologue la protéine humaine KIAA1009. Nous démontrons, par stratégie siRNA, l'implication de cette protéine au cours de deux processus cellulaires majeurs : la prolifération et la différenciation. En effet, la protéine QM1/KIAA1009 joue un rÎle décisif dans le déroulement normal de la mitose et plus particuliÚrement dans la ségrégation correcte des chromosomes. De plus, nous démontrons que la protéine QN1/KIAA1009 participe à la voie de signalisation du NGF au cours de la différenciation des cellules PC12. L' ensemble de ces résultats montre que la protéine QN1/KIAA1009 est un nouvel acteur clé de la mitose.PARIS5-BU-Necker : Fermée (751152101) / SudocSudocFranceF
Anatomie de la rétine
La neurorĂ©tine est une unitĂ© fonctionnelle du systĂšme nerveux central assurant la conversion dâun signal lumineux en un influx nerveux. Dâorigine neuroectodermique, dĂ©rivĂ©e du diencĂ©phale, la neurorĂ©tine est un tissu stratifiĂ©, composĂ© de six types de cellules neuronales (deux types de photorĂ©cepteurs : les cĂŽnes et les bĂątonnets ; les cellules horizontales, bipolaires, amacrines et ganglionnaires) et de trois types de cellules gliales (les cellules gliales de MĂŒller, les astrocytes et les cellules microgliales). La neurorĂ©tine repose sur lâĂ©pithĂ©lium pigmentaire rĂ©tinien, lâensemble constituant la rĂ©tine. Lâexistence des barriĂšres hĂ©mato-rĂ©tiniennes interne et externe et des jonctions intra-rĂ©tiniennes rend compte de la finesse de la rĂ©gulation des Ă©changes de la rĂ©tine avec la circulation et au sein de la rĂ©tine elle-mĂȘme. La zone centrale de la rĂ©tine humaine, la macula, zone hautement spĂ©cialisĂ©e pour assurer lâacuitĂ© visuelle, prĂ©sente des spĂ©cificitĂ©s anatomiques. Les mĂ©thodes dâimagerie rĂ©centes permettent dâenrichir nos connaissances sur les caractĂ©ristiques anatomiques et fonctionnelles de la rĂ©tine, qui restent encore imparfaitement dĂ©crites
Glial cells of the human fovea.
The exact cellular types that form the human fovea remain a subject of debate, and few studies have been conducted on human macula to solve this question. The purpose of this study was to perform immunohistochemistry on fresh human samples to characterize the glial cells that form the human fovea.
Immunohistochemistry was performed using antibodies against proteins expressed in astrocytes or in retinal MĂŒller glial cells or both types of cells on six human macula obtained from eyes enucleated for peripheral intraocular tumors and on two postmortem eyes from healthy donors. The posterior poles of the enucleated eyes were cryosectioned and stained with antibodies against the glial proteins GFAP, vimentin, CRALBP, glutamine synthetase, and connexin 43.
A population of cells positive for GFAP and negative for glutamine synthetase and CRALBP that express connexin 43 were identified at the roof of the foveal pit. These cells are distinct from the MĂŒller cone cells described by Yamada and Gass, suggesting that another type of foveal glial cells, most likely astrocytes, are present in the human fovea.
This study showed that in humans, astrocytic glial cells cover the foveal pit. Their roles in macula homeostasis and mechanisms of macular diseases disease remain to be determined
Optical phase contrast imaging of human retinal cells by changing the tissue refractive index
Purpose : Based on oblique partially coherent illumination of transparent samples, we developed a simple custom Optical Phase Imaging (OPI) microscope providing a label-free, semi-quantitative phase contrast imaging. The aim of this study was to explore this ex-vivo modality for retinal imaging and correlate it with standard clinical images and fluorescence microscopy. Methods : Multimodal macular imaging was performed on the flat-mounted retina of an eye presenting an epiretinal membrane with cystoid macular edema, enucleated for a peripheral melanoma. After glial fibrillary acidic protein (GFAP) - aquaporin (AQP)-4 â collagen (Col)-IV co-immuno-labeling and nuclei staining, the retina was cleared by index matching in a medium of refractive index (RI) 1.46 to decrease scattering for high-resolution deep-tissue ex vivo imaging. We performed a comparison of the clinical examinations obtained by Optical Coherence Tomography-Angiography and fluorescein angiography before enucleation, with the images obtained with confocal microscopy and OPI microscopy. Ex-vivo imaging of the retina mounted in a medium with a lower RI (1.40), close to the mean RI of Muller glial cell (MGC), was then repeated to better view the latter cells. Results : The retinal vessels were used as landmarks for correlating all imaging modalities. OPI microscopy allowed for different contrast imaging depending on the RI of the mounting medium. With the high RI medium (1.46), deep contrast imaging of nuclei and intraretinal cysts was obtained. The solution with a RI of 1.4 provided an improvement in the contrast of the retinal structures, from the inner layer (AQP4-positive MGC, epi-retinal membrane, nerve fibers surrounded by GFAP-positive astrocytes) to the photoreceptor segments. No AQP4 labeling was observed inside the cyst. AQP4-positive, GFAP-negative cells were visualized on the ColIV-labeled epi-retinal membrane, demonstrating that the membrane is made of retinal Muller glial cells. Conclusions : This morphological correlative imaging study demonstrated OPI on numerous cellular structures of a human retina by tuning the tissue RI. This label-free in-depth imaging modality offers a new research tool to study the cellular origin of retinal diseases
Les ĆdĂšmes maculaires
LâĆdĂšme maculaire est une augmentation de volume de la macula, zone centrale de la rĂ©tine, responsable de lâacuitĂ© visuelle. Des symptĂŽmes visuels handicapent la vie de millions de patients atteints dâĆdĂšme maculaire secondaire Ă une maladie chronique et parfois aiguĂ« de la rĂ©tine. Les protĂ©ines qui neutralisent la voie du facteur de croissance de lâendothĂ©lium vasculaire (VEGF) ou les glucocorticoĂŻdes, au prix dâinjections intraoculaires rĂ©pĂ©tĂ©es pendant des annĂ©es, limitent les symptĂŽmes visuels. Mieux comprendre pourquoi et comment lâĆdĂšme se forme et comment les molĂ©cules thĂ©rapeutiques exercent un effet anti-ĆdĂ©mateux permettra de mieux prĂ©venir la survenue de cette complication rĂ©tinienne handicapante et cĂ©citante