No abstract

In human lens proteins, advanced glycation endproducts (AGEs) originate from the reaction of glycating agents, e.g., vitamin C and glucose. AGEs have been considered to play a significant role in lens aging and cataract formation. Although several AGEs have been detected in the human lens, the contribution of individual glycating agents to their formation remains unclear. A highly sensitive liquid chromatography–tandem mass spectrometry multimethod was developed that allowed us to quantitate 21 protein modifications in normal and cataractous lenses, respectively. N6-Carboxymethyl lysine, N6-carboxyethyl lysine, N7-carboxyethyl arginine, methylglyoxal hydroimidazolone 1, and N6-lactoyl lysine were found to be the major Maillard protein modifications among these AGEs. The novel vitamin C specific amide AGEs, N6-xylonyl and N6-lyxonyl lysine, but also AGEs from glyoxal were detected, albeit in minor quantities. Among the 21 modifications, AGEs from the Amadori product (derived from the reaction of glucose and lysine) and methylglyoxal were dominant.

Post-operative capsular opacification (PCO) is a multifactorial physiological consequence of cataract surgery. Opacification involving the central posterior capsule has a significant impact on high and low contrast acuity and low contrast sensitivity. The assessment of PCO on cadaver eyes, experimental studies and culture models and in clinical studies has provided an understanding of its pathogenesis. The proliferation, migration and abnormal differentiation of residual lens epithelial cells and fibers in the capsular bag have been implicated in the pathogenesis of PCO. The incidence and severity of PCO correlates to the use of surgical techniques, intraocular lens (IOL) optic edge designs and IOL materials. This article summarizes the clinical studies with recommendations for retarding the development of central PCO. It discusses experiments with pharmacological agents broadly categorized as anti-inflammatory, immuno-modulating, antiproliferative, antiadhering and antitransdifferentiating agents for the prevention of PCO. These studies will remain critical for future endeavors undertaken for the eradication of PCO.

Background: Human lens proteins accumulate pigmented, protein-cross-linked AGE adducts during cataract formation, and the mechanisms of their formation are poorly understood. Results: UVA-excited kynurenines can oxidize ascorbate under anoxic conditions and promote synthesis of AGEs. Conclusion: UVA light-excited kynurenines promote AGE synthesis and contribute to cataract formation. Significance: This study provides a mechanism for UVA light-mediated damage to lens proteins during cataract formation.

Staining the anterior capsule with trypan blue affected the density and viability of LECs.