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Y Courtois

Publications and source records attributed to Y Courtois.

239 records · Page 14Linked to original sources
PubMedDate not supplied

Analysis of the rat lens epithelial cell nucleus during ageing by scanning cytophotometry.

Nuclei of rat lens epithelial cells were stained with eosin and hematoxylin in order to investigate by cytophotometric analysis the effects of cellular ageing on their morphologic parameters and chromatin compaction. Our results demonstrate a decrease in the size of the nucleus without modification in their shape as a function of age. Older nuclei also have more condensed and heterogeneously distributed chromatin than young nuclei. The homogeneous population of nuclei in the young epithelium gave rise to a highly heterogeneous population in the old animal for both morphometric and densitometric parameters. In very old rats a small percentage of the cell nuclei retained young characteristics. These data support an earlier observation that growth of the lens epithelial cells declines with age.

Aging↗
PubMedDate not supplied

Nitric oxide in the eye: multifaceted roles and diverse outcomes.

Recent works have highlighted the role of nitric oxide in a wide array of disease entities, including septic shock, hypertension, cerebral ischemia, and chronic degenerative diseases of the nervous system. The functions of nitric oxide appear very diverse, having actions on vascular tone, neurotransmission, immune cytotoxicity, and many others. Nitric oxide is an important mediator of homeostatic processes in the eye, such as regulation of aqueous humor dynamics, retinal neurotransmission and phototransduction. Changes in its generation or actions could contribute to pathological states such as inflammatory diseases (uveitis, retinitis) or degenerative diseases (glaucoma, retinal degeneration). Localization in the eye and biochemical characteristics of nitric oxide will be reviewed. A better understanding of the nitric oxide pathway will be the key to the development of new approaches to the management and treatment of various ocular diseases.

Administration, Topical↗
PubMedDate not supplied

Phosphorylation and protein kinase activities of chromosomal non histone proteins from chick embryo fibroblasts.

Confluent chick embryo fibroblasts were cultured in vitro in (i) medium which prevented the cells from dividing, (ii) medium which stimulated the cells to divide synchronously, (iii) medium without lysine in which the cells were blocked in G1. Chromosomal non histone proteins (NHP) were extracted from cells pulse labelled with 32P phosphate, and the radioactivity analyzed by acrylamide gel electrophoresis. Several radioactive peaks were found all along the gel in the NHP from confluent and stimulated cells. The highest phosphorylation was found in the fast moving proteins, but the stimulation of the cells increases the phosphorylation of the slower moving proteins. In the NHP from cells cultured in the medium without lysine only the slow migrating proteins were phosphorylated. NHP were extracted from unlabelled cell cultures in the three different media, incubated with [gamma-32P] ATP and analyzed by acrylamide gel electrophoresis. Highly labelled peaks were observed in the fast moving proteins from stimulated cells and from cells cultured in a medium deprived from lysine. By comparing in vivo and in vitro phosphorylation, it can be concluded that in confluent cells the turnover of bound phosphate is slow. In stimulated cells there is a fast turnover of the phosphate bound to fast turnover of the phosphate bound to a small group of fast migrating proteins and very little turnover of the phosphate bound to slow migrating proteins. The cells were incubated with labelled lysine and NHP analyzed by gel electrophoresis. The radioactivity of individual NHP varied with the culture conditions, but in all cases, there was little radioactivity in the fast moving proteins. The phosphate groups submitted to a fast turnover are bound to stable proteins. Phosvitin and casein kinase activities were measured in the NHP fractions. Nine-ten peaks of activities were observed with each substrate. Some variations were observed which apparently correlate with the culture conditions.

Adenosine Triphosphate↗
PubMedDate not supplied

[Recent findings on the etiopathogenesis of subretinal neovascularization].

The proliferation of new vessels originating from the choriocapillaris, constitute the turning point in Age Related Macular Degeneration. Vaso-proliferative, or better vaso-modulator, factors have an effect upon the subsequent steps of angiogenesis. Receptors especially for the fibroblast growth factor have been identified on ocular vascular endothelial cells. Basement membranes are the storage site of the factor. In vitro, vaso-proliferative factors, as Fibroblast growth factors, and vaso-inhibitor factors, as Transforming Growth Factor B, were identified in cell cultures of pigment epithelium. On the other hand, proliferations of pigment epithelium cells surround the neovascular sprouts and induce involution of experimental subretinal new vessels. Experimentally and clinically, inflammatory cells are found in the vicinity of the new vessels. Their effect could add or initiate new vessel proliferation. Angiogenesis is an extremely complex phenomenon but results of research on the role of pigment epithelium and vaso-modulators factors help to clarify it partially.

Animals↗