[The biochemical study in the nucleus opacification of the senile cataractous lens].

The lens nucleus has various colors, sizes and hardness. It is of significance to investigate the components of the nucleus and the factors participating in the mechanism of development of cataract. Recently, the author demonstrated that free lipid in cataract does not undergo quantitative change, compared with that in the normal lens but that the cholesterol and phospholipid in the nucleus and cortex increase in the urea-soluble protein fraction. An assay of lipid-protein complex (lipoprotein) was made and also quantitative changes were studied using nucleus with different colors in senile cataract. The study was made by the technique developed by the author because no other experimental procedure has been established for lipoprotein in the tissue. Chylomicron, VLDL, LDL and HDL were identified in lipoprotein. The amount of lipoprotein decreased as the color of the nucleus became dense, but only HDL among these increased. The catabolism of lipoprotein advanced when the color of nucleus changed from light yellow to brown, suggesting that disorder in mass transfer is caused.