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Pulse radiolysis has been used to study the reactions of 3-hydroxykynurenine and kynurenine with solvated electrons, superoxide radicals, hydroxyl radicals and azide radicals. Both 3-hydroxykynurenine and kynurenine react with solvated electrons with diffusion controlled rate constants (k = 2.5 x 10(10) M-1 s-1 and 2.3 x 10(10) M-1s-1, respectively).(More)
The retinal pigment epithelium (RPE) is a monolayer of highly pigmented cells lining the inner aspect of Bruch's membrane. This pigmentation is due to eumelanin and a possible antioxidant role of melanin is reported here. The photo-oxidation of A2E, a constituent of RPE lipofuscin, leads to the sequential addition of up to nine oxygen atoms and/or the(More)
The physical properties of membranes derived from the total lipids extracted from the lens cortex and nucleus of a 2-year-old cow were investigated using EPR spin-labeling methods. Conventional EPR spectra and saturation-recovery curves show that spin labels detect a single homogenous environment in membranes made from cortical lipids. Properties of these(More)
PURPOSE To quantitate aging of the primate lens by changes in the absorption characteristics that are related to the yellowing of lens protein. METHODS The lenses of lower primates and humans were sectioned anterior to posterior every 0.25 mm, and the UV-visible spectrum of each section was measured to determine the cumulative spectra along the visual(More)
Fluorescent material generated in the human retina accumulates within lipofuscin granules of the retinal pigment epithelium (RPE) during aging. Its presence has been suggested to contributed to various diseases including age-related macular degeneration. Because this material absorbs light at wave lengths as long as 550 nm, photophysical studies were(More)
The physical properties of a membrane derived from the total lipids of a calf lens were investigated using EPR spin labeling and were compared with the properties of membranes made of an equimolar 1-palmitoyl-2-oleoylphosphatidylcholine/cholesterol (POPC/Chol) mixture and of pure POPC. Conventional EPR spectra and saturation-recovery curves show that spin(More)
The physical properties of membranes derived from the total lipid extract of porcine lenses before and after the addition of cholesterol were investigated using EPR spin-labeling methods. Conventional EPR spectra and saturation-recovery curves indicate that the spin labels detect a single homogenous environment in membranes before the addition of(More)
PURPOSE We have shown previously that aging of human Bruch's membrane affects the attachment, survival and gene expression profile of the overlying retinal pigment epithelium (RPE). Herein we determine the effects of Bruch's membrane aging on RPE phagocytosis of rod outer segments. METHODS Explants of human Bruch's membrane were prepared from cadaver(More)
An experimental setup for measurement of time-resolved autofluorescence of the human eye fundus is demonstrated. The method combines laser scanning technique and time-correlated single photon counting. The light source is a laser diode, delivering pulses of about 100 ps duration at a repetition rate of 40 MHz. The excitation wavelength is 446 nm and the(More)
The purpose of this study is to determine the transmission properties of the anterior segment of the human eye as a function of age and relate those changes to possible consequences for retinal disorders. For this a new method has been developed. This consists of a probe which is inserted into the posterior sclera and detects light passing through the(More)