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PURPOSE Lipofuscin accumulates in human retinal pigment epithelium (RPE) cells with age and may be the main factor responsible for the increasing susceptibility of RPE to photo-oxidation with age. As the composition, absorption, and fluorescence of lipofuscin undergo age-related changes, the purpose of this study was to determine whether photoreactivity of(More)
PURPOSE To determine whether retinal pigment epithelial (RPE) cells, which reportedly express N-cadherin as their major cadherin cell adhesion protein, also express the more common epithelial cadherin, E-cadherin. METHODS Cadherins expressed by human RPE cells in situ were examined by western blot analysis of extracts prepared from the RPE of human adult(More)
PURPOSE To determine how time at confluence affects the properties of cultured human retinal pigment epithelium (RPE) cells, with emphasis on the adherens junction. METHODS Cultures were maintained at confluence without passage for intervals to several months. Adherens junction proteins (N-cadherin, E-cadherin, alpha-catenin, beta-catenin, plakoglobin,(More)
PURPOSE To determine whether aging is accompanied by changes in aerobic photoreactivity of retinal pigment epithelial (RPE) melanosomes isolated from human donors of different ages, and to compare the photoreactivity of aged melanosomes with that of RPE lipofuscin. METHODS Human RPE pigment granules were isolated from RPE cells pooled into groups(More)
Methanol has neurotoxic actions on the human retina due to its metabolite, formic acid, which is a mitochondrial toxin. In methanol poisoned animals, morphologic changes were seen both in retinal photoreceptors and in cells of the underlying retinal pigment epithelium (RPE). Here the effects of formate exposure on the two retinal cell types were analyzed in(More)
PURPOSE Isolated melanosomes are known to have antioxidant properties but whether the granules perform an antioxidant function within cells is unclear. The aim of this study was to determine whether retinal pigment epithelium (RPE) melanosomes are competent to protect cultured cells against non-photic oxidative stress induced by treatment with H(2)O(2). (More)
PURPOSE To examine the accumulation and morphologic features of fluorescent inclusions in retinal pigment epithelial (RPE) cells in vitro and to determine whether accumulation correlates with parameters of age. METHODS Cultured human RPE cells were maintained undisturbed at confluence for intervals as long as 2 years and then were examined for(More)
PURPOSE To determine whether previously shown photodynamic (PD)-induced inhibition of specific photoreceptor outer segment (POS) phagocytosis by ARPE-19 cells is associated with reductions in receptor proteins mediating POS phagocytosis, and if PD treatment with merocyanine-540 (MC-540) produces additional effects leading to its inhibition of nonspecific(More)
PURPOSE We determined whether photic stress differentially impairs organelle motility of RPE lipofuscin and melanin granules, whether lethal photic stress kills cells in proportion to lipofuscin abundance, and whether killing is modulated by melanosome content. METHODS Motility of endogenous lipofuscin and melanosome granules within the same human RPE(More)
The emission properties of ocular lipofuscin granules isolated from human retinal pigment epithelial cells are examined by using steady-state fluorescence spectroscopy and spectrally resolved confocal microscopy. The shape of the emission spectrum of a thick sample of lipofuscin granules dried on glass varies with excitation energy. The polarization of this(More)