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Low glycation level and browning in human cataracts.
P Vidal1, J Fernandez-Vigo, J Cabezas-Cerrato
1Chair of Physiopathology, Hospital General de Galicia Clinico Universitario, University of Santiago, Santiago de Compostela, Spain.
Acta Ophthalmologica
|April 1, 1988
Summary
Human lens glycation is significantly higher in diabetics but does not cause cataract browning. Other age-related compounds, not glycation, likely contribute to the characteristic color of senile and diabetic cataracts.
Area of Science:
- Ophthalmology
- Biochemistry
- Gerontology
Background:
- Human cataracts, particularly senile and diabetic types, exhibit a characteristic brownish-yellow coloration.
- Glycation, a process involving the non-enzymatic addition of sugars to proteins, is implicated in aging and diabetes.
- The role of glycation in the development of cataract coloration requires further elucidation.
Purpose of the Study:
- To quantify the extent of human lens glycation in diabetic and non-diabetic individuals.
- To investigate the correlation between lens glycation and the brownish-yellow coloration of cataracts.
- To determine the primary contributors to cataract browning.
Main Methods:
- Analysis of 236 human cataract samples (53 diabetic, 183 non-diabetic).
- Quantification of glycation using the 5-hydroxymethylfurfural/thiobarbituric acid (5-HMF/TBA) method.
- Spectrophotometric measurement of brownish-yellow coloration, indicative of advanced Maillard reaction products.
Main Results:
- Lens glycation was three times higher in diabetic patients compared to non-diabetic controls.
- Glycation showed a positive correlation with age in the non-diabetic group.
- No significant difference in the degree of browning was observed between the two groups.
- Cataract browning was uncorrelated with primary glycation products measured by the 5-HMF/TBA method.
Conclusions:
- Lens glycation in human cataracts is relatively mild and does not solely determine the characteristic brownish-yellow color.
- Advanced glycation end-products are not the primary cause of cataract browning.
- Other age-associated colored compounds likely interfere with spectrophotometric measurements at relevant wavelengths, contributing to cataract coloration.