Instrumental development is proposed for a prototype in situ Raman/fluorescence probe and for an automated Raman/fluorescence microprobe (10-20 Mum resolution; 1Mum or less is possible) surface scanning system. The first technique will be applied to five (5) rabbits' eyes to investigate the effects of repetitive near UV exposure on the -SH level, and to compare the rates of fluorophor production between exposed and unexposed lenses of the same animal. It is to test the hypothesis that in a non-rodent system the -SH level decrease at an accelerated rate precedes the development of visible opacity. The second technique will obtain useful information about detailed distributions of lens constituents and fluorophors on lens slices. The full topograph of either Raman or fluorescence signals from the surface of a lens section should reveal the differences between cataractous and noncataractous microareas of the same lens. It is proposed to pursue the finding that the red fluorescence which is highly characteristic of brunescent cataract can be generated by near UV irradiation of a mixture of 3-OH kynurenine and Gamma-crystallin. Specifically we propose: 1) to examine the nature of photochemical reactions between Alpha-, Beta- and Gamma-crystallins; 2) to investigate the photoreactivity and formation of new fluorophors from 3-OH kynurenine which has been diffused into the rat lens; 3) to compare the fluorescence properties of these fluorophors and the red fluorophors detected in older and brunescent human lens by laser Raman instrumentation; and 4) to explore the nature of the electronic state responsible for red fluorescence. Other studies include variations of sulfhydryl along VA for normal human lenses between 58 and 100-year of age, and Raman evidence for disulfide and methionine sulfoxide formation in human senile cataract.
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