Elevated Hcys and low methionine were risk factors for CRVO in an Indian population.

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The amino acids lysine and glycine are reported to react with glucose at physiological pH and temperature and undergo non-enzymic glycation. Three other amino acids present in relatively larger amounts in the lens i.e. alanine, aspartic acid and glutamic acid were also found to undergo non-enzymic glycation as found by incorporation of uniformly labelled (U-[14C]) glucose into the amino acids. The glucose incorporation was 1.6 to 2.5% for alanine, 35 to 50% for aspartic acid and 2.3 to 3.3% for glutamic acid. Each amino acid of varying concentrations lowered the extent of in vitro glycation of lens proteins significantly in glucose-treated homogenates of normal lens from humans. The decrease in glycation for alanine was between 32 and 69%, that for aspartate was between 18 and 74%, and for glutamate was between 52 to 74%. Decreased glycation was greater for higher concentrations of glucose. Scavenging of intracellular glucose and decreasing the extent of glycation of lens proteins could be the mechanism of action by which the amino acids alanine, aspartic acid and glutamic acid could exercise a beneficial effect on cataract and diabetic retinopathy.

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Aim To estimate the arylesterase activity of serum paraoxonase-1 (PON1-ARE), which is reported to have an antioxidant and antiatherogenic potential and to correlate with plasma homocysteine (Hcys) and plasma TBARS in young adult central retinal venous occlusion (CRVO) patients. Methods A case-control prospective study carried out in 10 CRVO patients (mean age 27 ± 5 years; 7 males, 3 females) and 20 healthy controls (mean age 29 ± 5 years; 15 males, 5 females). Results The CRVO patients showed a significantly lowered serum PON1-ARE activity (P ¼ 0.009) along with a significant increase in the levels of plasma Hcys (P ¼ 0.018) when compared to the control subjects. There was a negative correlation between serum PON1-ARE and plasma Hcys levels (P ¼ 0.058) as well as between PON1-ARE and plasma TBARS levels (P ¼ 0.001) in the CRVO patients. Conclusion This is the first report of lowered serum PON1-ARE level as a risk factor for CRVO (OR ¼ 1.108, CI ¼ 0.914, 1.314; P ¼ 0.296), which is found to correlate with oxidative stress.