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Proceedings Paper

Photo-oxidative stress in the eye: role of retinal pigment epithelial pigments
Author(s): Randolph D. Glickman; Alexander E. Dontsov; Michail A. Ostrovsky; Neeru Kumar; Meena Vendal; Mary Ann Gonzales
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Paper Abstract

The pigments of the retinal pigment epithelium, i.e. the intracellular granules of melanin, lipofuscin, and melanolipofuscin, have been shown to catalyze free radical activity, especially when illuminated with visible or ultraviolet light. An important question is whether these reactions are sufficient to produce oxidative damage in the eye. To address this question, the relative photoreactivity of isolated RPE pigment granules towards polyunsaturated fatty acids has been determined, including the dark as well as the light-stimulated reactions. Hydroperoxide derivatives of docosahexaenoic acid were produced by irradiation with short wavelength (< 550 nm) visible light when RPE pigments were present. Although melanosomes exhibited the greatest light-induced activity in these reactions, lipofuscin granules induced peroxidation of fatty acids in the dark. In intact, cultured RPE cells, the existence of pigment-medicated photo-reactions were demonstrated with a fluorescent indicator probe of oxidation, 2',7'- dichlorofluorescein, that was photooxidized in probe-labeled cells in a wavelength dependence fashion with peak activity in the 450 to 500 nm region. This behavior resembled the action spectrum for melanin reactivity. These findings support the hypotheses that the RPE pigments contribute to general photooxidative stress in ocular tissue, and that accumulation of lipofuscin pigment contributes to age-related oxidative stress in the RPE.

Paper Details

Date Published: 17 September 1999
PDF: 11 pages
Proc. SPIE 3863, 1999 International Conference on Biomedical Optics, (17 September 1999); doi: 10.1117/12.364425
Show Author Affiliations
Randolph D. Glickman, Univ. of Texas Health Science Ctr. (United States)
Alexander E. Dontsov, Institute of Bio-Chemical Physics (Russia)
Michail A. Ostrovsky, Institute of Bio-Chemical Physics (Russia)
Neeru Kumar, Univ. of Texas Health Science Ctr. (United States)
Meena Vendal, Univ. of Texas Health Science Ctr. (United States)
Mary Ann Gonzales, Univ. of Texas Health Science Ctr. (United States)

Published in SPIE Proceedings Vol. 3863:
1999 International Conference on Biomedical Optics
Qingming Luo; Britton Chance; Lihong V. Wang; Steven L. Jacques, Editor(s)

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