Bettelheim F A, Li L, Zeng F F
Chemistry Department, Adelphi University, Garden City, NY 11530, USA.
Res Commun Mol Pathol Pharmacol. 1998 Oct;102(1):3-14.
Cataract formation in diabetic lenses has been attributed to polyol-osmotic pressure-generated influx of water. The ensuing swelling in the form of pocket and lake accumulations cause light scattering. The authors tested whether clear lenses of diabetic patients show different hydration properties than age matched normal lenses. Normal and diabetic human lenses were investigated for their nonfreezable water content by differential scanning calorimetry. The total water content of the lens sections were studied by thermogravimetric analysis. Non-cataractous diabetic lenses in all three regions showed a higher total water content than normal lenses. The nonfreezable water content, seems to increase with age in diabetic lenses and decrease with age in normal human lenses. Thus, hydration changes in human diabetic lenses precede cataract formation. While syneresis, the release of bound water into the bulk, is part of the normal aging process, it appears to occur in the younger diabetics only. In older diabetics syneresis is halted or even reversed. This may be due to the glycation of lens proteins in diabetic patients which tends to immobilize water and therefore, reverse the syneresis due to aging.
糖尿病性晶状体中的白内障形成归因于多元醇渗透压导致的水分流入。随之而来的以囊袋和液体积聚形式出现的肿胀会引起光散射。作者测试了糖尿病患者的透明晶状体与年龄匹配的正常晶状体是否具有不同的水合特性。通过差示扫描量热法研究了正常和糖尿病患者晶状体的不可冻结水含量。通过热重分析研究了晶状体切片的总含水量。所有三个区域的非白内障性糖尿病晶状体的总含水量均高于正常晶状体。在糖尿病晶状体中，不可冻结水含量似乎随年龄增加，而在正常人类晶状体中则随年龄减少。因此，人类糖尿病晶状体中的水合变化先于白内障形成。虽然脱水收缩，即结合水释放到主体中，是正常衰老过程的一部分，但它似乎仅发生在年轻的糖尿病患者中。在老年糖尿病患者中，脱水收缩会停止甚至逆转。这可能是由于糖尿病患者晶状体蛋白的糖基化倾向于固定水分，因此逆转了由于衰老导致的脱水收缩。
