Date of Award

10-2-1993

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Anatomy and Cell Biology

Abstract

The basis of this study was the prediction that bovine anterior lens capsules (LCs) and Descemet's membranes (DMs) would accumulate Maillard reaction products with age and that these products could be detected by immunoelectron microscopy. In addition, it was predicted that Maillard reaction product content could be related to alterations in basement membrane (BM) morphology. Antiglucitollysine and antipyrraline antibodies were used to detect early and advanced Maillard reaction products in intact glucose-treated and untreated bovine anterior LCs and DMs. Light microscopy revealed that old LCs and DMs were significantly thicker than young LCs and DMs. The distribution and content of Maillard reaction products in the two BMs were localized by electron microscopic detection of immunogold bound to adhering monoclonal antibodies. Antiglucitollysine is specific for glucitollysine, but also crossreacts with mannositollysine. Glucitollysine and mannositollysine are the reduced forms of the Schiff base and the Amadori product (AP), both of which are early Maillard reaction products. Antipyrraline recognizes only the advanced glycosylation endproduct (AGE) pyrraline, a nonfluorescent pyrrole compound. The immunolocalization and biochemical assays of glucose-treated old LCs and old DMs both indicated that intact BMs were capable of forming significant concentrations of early and advanced Maillard reaction products in the presence of glucose under physiological conditions. Results from immunolabeled untreated (in vivo) LCs and DMs showed no significant age-related differences in the density of early products as measured by antiglucitollysine. In contrast, antipyrraline results showed significantly greater immunoreactivity in old LCs versus young LCs. In addition, fluorescence results indicated that both old LCs and old DMs contained higher concentrations of fluorescent advanced products than respective young BMs. Resistance of treated and untreated LCs and DMs to trypsinization was determined. Glucose-treated old DMs were significantly more resistant to trypsinization than untreated old DMs, and untreated old DMs were significantly more resistant to trypsinization than untreated young DMs. These results suggest that fluorescent advanced Maillard reaction products accumulate in DM with age, and that these products may crosslink the proteins within the BM. In summary, the results of the current study indicate that intact bovine LCs and DMs form early and advanced Maillard reaction products in vitro in the presence of glucose, and accumulate advanced products with age. The advanced products in turn may contribute to age-related BM thickening by increasing the total number of crosslinks present and thereby slow the turnover of BM proteins. (Abstract shortened by UMI.)

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