Retinal proliferation

Numerous studies have demonstrated that degradation products of (3-carotene exhibit deleterious effects in cellular systems (Alija et al., 2004, 2006 Hurst et al., 2005 Salerno et al., 2005 Siems et al., 2003). A mixture of (3-carotene degradation products exerts pro-apoptotic effects and cytotoxicity to human neutrophils (Salerno et al., 2005 Siems et al., 2003), and enhances the geno-toxic effects of oxidative stress in primary rat hepatocytes (Alija et al., 2004, 2006), as well as dramatically reduces mitochondrial activity in a human leukaemic cell line, K562, and RPE 28 SV4 cell line derived from stably transformed fetal human retinal pigmented epithelial cells (Hurst et al., 2005). As a result of degradation or enzymatic cleavage of (3-carotene, retinoids are formed, which are powerful modulators of cell proliferation, differentiation, and apoptosis (Blomhoff and Blomhoff, 2006). 

Hu, W, Jiang, A, Liang, J, Meng, H, Chang, B, Gao, H, and Qiao, X, 2008. Expression of VLDLR in the retina and evolution of subretinal neovascularization in the knockout mouse model s retinal angiomatous proliferation. Invest Ophthalmol Vis Sci 49, 407 115. 

T. Kondo, K. Hosoya, S. Hori, M. Tomi, S. Ohtsuki, and T. Terasaki. PKC/MAPK signaling suppression by retinal pericyte conditioned medium prevents retinal endothelial cell proliferation. J. Cell. Physiol. 203 378-386 (2005). 

Metabohc derivatives of the fat-soluble vitamin retinol, which was first described in 1913. These metabolites play a central role in the visual process where the primary photoevent is attended by conversion of ll-cA-retinal to all-rrans-retinal. The oxidized metabolite retinoic acid is an agonist in cell growth and proliferation. 

Hermel, M., Heckelen, A., Kirchhof, B., Schrage, N.F. Inhibitory effect of ascorbic acid on human retinal pigment epithelial cell proliferation compared to cytostatic drugs-influence of histamine. Inflamm Res 50(Suppl 2), S93-S95... 

King RE, Kent KD, Bomser JA. 2005 Resveratrol reduces oxidation and proliferation of human retinal pigment epithelial cells via extracellular signal-regulated kinase inhibition. Chem Biol Interact 151 143-149. 

Hoffman S, Gopalakrishna R, Gundimeda U, Murata T, Spee C, Ryan SJ, Hinton DR (1998) Verapamil inhibits proliferation, migration and protein kinase C activity in human retinal pigment cells. Exp Eye Res 67 45-52... 

Neovascular glaucoma is a condition maiked by new blood vessel proliferation on the iris and in the anterior chamber angle usually as a result of retinal or anterior segment ischemia/hypoxia. Neovascularization of the iris usually appears first on the surfece of the iris adjacent to the pupillary border.These vessels are fine in caliber and may have aneurysm-like outpouchings. Gonioscopic evaluation may reveal vessels in the anterior chamber angle even in the absence of iris vessels. 

The neovascular lesions of talc retinopathy are thought to be associated with peripheral arteriolar nonperfusion, which leads to retinal ischemia and secondary neovascularization. Such a pathogenesis is quite similar to that seen in sickle cell retinopathy and is confirmed by the predominantly supertemporal location of the neovascular proliferation. Macular fibrosis with significant visual loss has also been associated with talc retinopathy. 

To provide a complete assessment of all these variables, the final evaluation of the safety of ophthalmic products must be made in the in vivo model using the preparation under the proposed conditions for use, following tissue compatibility with many of the techniques already discussed. Irrigating solutions of low viscosity may have limited contact, while the gel-like viscoelastic materials, which maintain the comeal dome, or the solutions and gases used as vitreous replacements to prevent retinal detachment, may have prolonged contact with delicate ocular tissues or the retina. A recent therapy involves treatment for neovascularization of the retina, a disease in which proliferation of blood vessels can lead to blindness. The treatment combines a systemic chemical that localizes... 

Vitamin A and its derivatives retinal and retinoic acid have many essential biological roles in such processes as vision, regulation of cell proliferation and differentiation, and as morphogenetic agents during embryonic... 

Reichenbach et al., 1994b Sharma and Ehinger, 1997b) the same sequence of cytogenesis is found. There are no estimates as to how many amacrine cells are produced in the early phase and how many in the late phase of proliferation. In species in which the retinal development takes place over a short period of time (Xenopus), there is overlapping in the birth dates of cells, whereas species in which retinal development is extended (monkeys), birthdays are more sharply demarcated. As discussed earUer, the birth order of retinal neurons is conserved during the evolution and reflects the evolutionary sequence of retinal neurons. 

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