PROTEIN GLYCATION AND IN-VIVO DISTRIBUTION OF HUMAN LENS FLUORESCENCE

Glycated proteins formed by the Maillard reaction were measured by fur osine determination in human normal lenses and in senile and diabetic cataracts. Furosine, an hydrolysis product of fructose-lysine adduct f ormed in the early stages of the Maillard reaction, was measured by hi gh performance liquid chromatography (HPLC). Furosine levels in diabet ic cataracts were found to be 3 to 4 times higher than those observed for senile cataracts. The increased glycation levels both in cortex an d nucleus were related to the increase of fluorescence determined in v itro by fluorometry and in vivo by Scheimpflug photography. Lens prote ins were incubated with glucose and it has been demonstrated that prot ein glycation occurred parallel with the increase in concentration of fluorescent chromophores that present similar characteristics as those observed in vivo. The results indicate that protein insolubilization seemed to involve preferentially glycated proteins and at least in dia betic cataracts, the process seems to be initiated in the cortical reg ion.