Year

2006

Degree Name

Master of Science by Research (Medicinal Chemistry)

Department

Science

Abstract

Barrier16 formation has been shown to occur in the lens with age. It is important to understand the physiological changes in the lens that occur upon the formation of the barrier and their implication on the onset of cataract and presbyopia (old man’s eyes). In this study, three factors related to the formation of the barrier were investigated: diffusion rate changes in the lens nucleus, oxygen consumption and cholesterol compositional changes in the lens with age. A Franz Cell was used to measure the diffusion rate changes in the nucleus of the human lens. No significant differences in the rate of diffusion between young and old lenses could be detected with this technique. The role of protein sulphydryls as secondary oxygen consumers was also studied. It was shown that protein sulphydryls reacted readily with oxygen, suggesting that protein sulphydryls are a secondary O2-consumption system in the center of the lens. Mitochondria are the primary oxygen consumers in the lens. A technique for the quantification of cholesterol in lipid extracts was developed. Results obtained were comparable to published results using traditional methods. The concentration of cholesterol in the young human lens was found to be approximately 3-fold greater than that of the bovine, ovine and porcine lenses, and ~5 times greater x than in the gallinaceous lens. These differences were even more pronounced when an elderly human lens was examined. The nucleus of the human lens was found to have a higher level of cholesterol content than that in the cortex and the concentration of cholesterol also exhibited a significant increase with age in both nuclear and barrier regions.

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