The retinal pigment epithelium. Chemical composition and structure.

Investigative ophthalmology 10/1974; 13(9):675-87.
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    ABSTRACT: In the process of autophagy, parts of the cell's own cytoplasm are enclosed by membranes and subsequently digested by enzymes. Autophagy is a well-known process found in various tissues under different conditions (See Refs.). Autophagy in visual cells was first documented by Rem and Young (1977) and Rem (1977), and was considered to be a general and important degradative pathway in visual cell metabolism. Recently, La Vail (1976) demonstrated that the shedding of disks from the tips of rod outer segments followed a circadian rhythm in rats. The peak period of disk shedding occurred shortly after the onset of the lighting period. In this study we have demonstrated, by quantitative analysis, that autophagy in rod inner segments follows a diurnal variation. The peak period of autophagic activity occurs about 3 h after the peak period of disk-shedding. Both peak periods take place in daytime, when the animals are less active. This finding further supports our assumption of autophagy being an important pathway in visual cell degradative mechanisms.
    Albrecht von Graæes Archiv für Ophthalmologie 08/1977; 203(3):261-270. · 2.33 Impact Factor
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    ABSTRACT: This paper is a survey of the literature in an attempt to provide the basis for our current understanding of the disciform process. Particular emphasis is placed on its pathogenesis and the role of subretinal neovascularization. No two lesions appear exactly alike because of the many stages and combinations possible. Gass (1967) has delineated the broad spectrum with the many different clinical manifestations of this disease process. Verhoeff and Grossman (1937) provided the histopathologic basis for our understanding of the disciform process. The histologic correlation of the clinical predisciform state would seem to offer the most promising information for understanding the pathogenesis of the disciform process (Frank et al. 1973; Green and Key 1977; Kornweig 1967; Sarks 1973 and 1976; Small et al. 1976; Zauberman 1970).It is hoped that this literature review has sufficiently emphasized the inherent deficiencies of strictly clinical studies and the need for an appropriate experimental animal model (Ryan 1979).Die vorliegende Arbeit gibt einen berblick ber die bisherige Literatur, um die Basis unseres gegenwrtigen Wissens um die disciformen Prozesse darzustellen.Besonderes Gewicht wird auf die Pathogenese und die Rolle von subretinalen Gefproliferationen gelegt. Aufgrund mglicher Kombinationen und Stadien sieht jede Lsion unterschiedlich aus (Gass 1977). Das breite Spektrum wird mit den verschiedenartigen klinischen Manifestationen dieses Krankheitsprozesses beschrieben.Verhoeff und Grossman (1937) beschrieben erstmals die histo-pathologischen Grundlagen fr unser gegenwrtiges Verstndnis von disciformen Prozessen. Die Gegenberstellung von histologischem und klinischem Befund des prdisciformen Stadiums verspricht am meisten zum Verstndnis der Pathogenese von disciformen Prozessen beizutragen (Frank et al. 1973; Green and Key 1977; Kornweig 1967; Sarks 1973, 1976; Small et al. 1976; Zauberman 1970).Mit vorliegender Literaturbersicht wird versucht, die unumgnglichen Lcken in den ausschlielich klinischen Studien darzustellen und die Notwendigkeit fr ein adequates tierexperimentelles Modell aufzuzeigen (Ryan 1980).
    Albrecht von Graæes Archiv für Ophthalmologie 01/1980; 215(1):1-20. · 2.33 Impact Factor
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    ABSTRACT: We investigated the effects of low power laser irradiation on the proliferation of retinal pigment epithelial (RPE) cells. Adult human RPE cells were artificially pigmented by preincubation with sepia melanin, and exposed to a single sublethal laser pulse (590nm, 1μs,<200mJ/cm2). DNA synthesis, cell number, and growth factor activity in irradiated RPE cells were subsequently monitored. The effect of sublethal laser irradiation on the “wound” healing response of an RPE monolayer in an invitro scratch assay was also investigated. Single pulsed laser irradiation increased DNA synthesis in pigmented RPE cells measured 6h post-treatment. In the scratch assay, laser irradiation increased the rates of cell proliferation and wound closure. Conditioned medium, collected 48h following laser treatment, increased cell proliferation of unirradiated cells. Irradiation increased RPE cell secretion of platelet-derived growth factor (PDGF)-B chain, and increased mRNA levels of several growth factors and their receptors, including PDGF, transforming growth factor-β1, basic fibroblast growth factor, epidermal growth factor, insulin-like growth factor, as well as heat shock proteins. This demonstrates, for the first time, that low power single pulsed laser irradiation stimulates the proliferation of RPE cells, and upregulates growth factors that are mitogenic for RPE cells.
    Cellular and Molecular Bioengineering 03/2008; 2(1):87-103. · 1.23 Impact Factor


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