No description available.

No description available.

Wang Zhi-Jun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 54-63). / ABSTRACT --- p.VI / Chapter I. --- INTRODUCTION --- p.1 / Chapter A. --- Literature review --- p.1 / Chapter 1. --- Retinal iron toxicity --- p.2 / Clinical siderotic retinopathy --- p.2 / Experimental siderotic retinopathy --- p.4 / Free radical involvement in siderotic retinopathy --- p.5 / Chapter 2. --- Experimental photic retinopathy in rats --- p.8 / Morphologic features --- p.8 / Free radical involvement in photic retinopathy --- p.9 / Chapter 3. --- Mechanisms of cell death --- p.9 / Necrosis --- p.10 / Apoptosis --- p.10 / Chapter B. --- Statement of the problems --- p.15 / Chapter II. --- MATERIALS AND METHODS --- p.17 / Chapter A. --- Siderotic retinopathy model --- p.17 / Animals --- p.17 / Reagents and equipment --- p.18 / Surgical procedures --- p.18 / Chapter B. --- Histochemical methods --- p.18 / Reagents and equipment --- p.19 / Paraffin sections --- p.19 / H&E staining --- p.19 / TUNEL technique --- p.20 / Schmeltzer's iron staining --- p.21 / Chinoy's ascorbic acid staining --- p.21 / Chapter C. --- Biochemical methods --- p.21 / Reagents and equipment --- p.22 / DNA gel electrophoresis --- p.22 / Analysis of ascorbic acid and uric acid --- p.23 / Chapter III. --- RESULTS --- p.24 / Chapter A. --- Observations in rats --- p.24 / Morphologic changes after H&E staining --- p.24 / Visualization of apoptosis by TUNEL technique --- p.25 / Internucleosomal DNA fragmentation --- p.26 / Negative staining of iron in the ONL --- p.27 / Positive staining of ascorbic acid in the ONL --- p.27 / Chapter B. --- Observations in rabbits --- p.27 / Positive staining of ascorbic acid in all retinal layers --- p.27 / Apoptosis occurred in all retinal layers --- p.28 / Changes of ascorbic acid and uric acid after iron implantatio --- p.28 / Chapter IV. --- DISCUSSION --- p.48 / Chapter V. --- CONCLUSION --- p.53 / References --- p.54

Retinal degenerative diseases are diseases that may severely affect vision of people at different ages. These include retinitis pigmentosa (RP) and age-related macular degeneration (AMD). The current treatments for these diseases are limited. Since dysfunction and atrophy of the RPE are the key factors in the development of retinal degenerative diseases, transplantation of healthy retinal pigment epithelial (RPE) cells might be a promising therapeutic strategy. However, homologous RPE cells may lead to host immune rejection and harvesting autologous RPE cells may cause severe complications. Autologous iris pigment epithelial (IPE) cells, which are relatively easy to obtain, possess the same embryonic origin and share similar characteristics as RPE cells. Therefore, they may be used as a substitute of RPE cells for transplantation. Increasing interests have been demonstrated with the use of substrate to support cell attachment, proliferation and differentiation, so that transplanted cells could maintain the differentiated phenotype and perform their normal functions. However, degradation of biodegradable substrates may cause the breakdown of functional cell monolayer and produce toxic byproducts. Therefore, the aim of current study is to investigate the in vitro characteristics of rat IPE cells cultured on surface modified non-degradable expanded-polytetrafluorethylene (ePTFE) substrates and host response to the substrates without cells. Primary pure IPE cells were successfully isolated from rat eyes, which provided abundant cells for subsequent experiments. IPE cells harvested from both Long Evans rats and Dark Agouti rats proliferated and reached confluence on fibronectin coated n-heptylamine modified (F-HA) ePTFE substrates. These cells exhibited cuboidal or polygonal morphology with heavy pigmentation. In addition to the typical epithelial cell morphology, rat IPE cells grown on F-HA ePTFE substrates were able to form a cell monolayer with functional formation of tight junctional complex between neighboring cells. The IPE cell monolayers also demonstrated increased phagocytosis of photoreceptor outer segments (POS) with time and expression of cellular retinylaldehyde-binding protein (CRALBP) that served an important role in the conversion of all-trans-retinal to 11-cis-retinal in visual cycle. In the in vivo study, F-HA ePTFE substrate was successfully transplanted into the subretinal space of Royal College of Surgeons (RCS) rat, which is a well-recognized animal model of retinal degeneration. The F-HA ePTFE substrate remained flat up to 4 weeks after transplantation and did not induce significant up-regulation of pro-inflammatory cytokines TNFα and IL1β as well as activation of Müller cells and astrocytes which occurred in response to retinal inflammation. In conclusion, rat IPE cells that were grown on F-HA ePTFE substrate were able to establish a monolayer with functional tight junctions and RPE-specific functions. The F-HA ePTFE substrate demonstrated good biocompatibility in the subretinal space of RCS rats. These findings provide a potential therapeutic strategy for retinal degeneration. / published_or_final_version / Anatomy / Doctoral / Doctor of Philosophy

No description available.

No description available.

Thesis (doctoral)--Rijksuniversiteit te Utrecht.

Thesis (doctoral)--Rijksuniversiteit te Utrecht.

Age-related macular degeneration (AMD) is the leading cause of blindness in the western world for people over 60 years of age. The most severe pathological event of AMD is choroidal neovascularization (CNV), the process of new vessel formation emerging from the choroid. The new vessels extend into the normally avascular photoreceptor cell layer, where they leak fluid and cause photoreceptor cell death. CNV is thought to be initiated by hypoxia and chronic inflammation, which occur due to abnormal, age-related changes within the retinal pigmented epithelium (RPE). These events cause increased expression of the angiogenic protein vascular endothelial growth factor (VEGF) via hypoxiainducible factor-1 (HIF-1), a transcription factor that is vital in regulation of cellular responses to hypoxic and inflammatory conditions. Increased VEGF signaling stimulates proliferation and migration of vascular endothelial cells and facilitates the neovascular process. To target the early pathological events that lead to CNV, we have engineered a novel gene therapy vector that uses HIF-1 regulation to stimulate production of an angiostatic protein, endostatin from the RPE. The purpose of this study was to characterize the activity of our hypoxiaregulated, RPE-specific promoter in vitro, and investigate the effects of regulated endostatin expression, driven by our regulated promoter, on CNV in a mousemodel. We found the regulated promoter construct has robust activity in vitro only in RPE cells, and is conditionally responsive in hypoxic conditions. / In the laserinduced CNV model, CNV area was 80% smaller (P<0.0001) in eyes treated with the hypoxia-regulated, RPE-specific endostatin vector than in untreated eyes. CNV area was equally reduced in eyes treated with an unregulated endostatin vector (CMV-endostatin). However, less endostatin protein was detected in eyes treated with the regulated vector. Since it is unknown whether broad and constitutive endostatin expression will have damaging effects within the retina, it may be safer to limit its expression to pathological conditions. We have demonstrated that local, hypoxia-regulated expression of endostatin can effectively inhibit CNV, and thus, offers the further possibility of a prophylactic treatment for neovascular AMD. / by George Wesley Tyler Smith. / Thesis (Ph.D.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

Yang, Yaping. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 156-165). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese.