Plasma Thiols and Taurine Levels in Central Retinal Vein Occlusion

Abstract

Purpose: To determine the plasma levels of the sulfur-containing amino-acids homocysteine, cysteine, cysteinylglycine, glutamylcysteine, glutathione, and taurine in patients with central retinal vein occlusion (CRVO) and in healthy subjects and to ascertain whether there are statistically significant differences between patients and controls.

Methods: Laser-induced fluorescence capillary electrophoresis was used to measure the plasma levels of homocysteine, cysteine, cysteinylglycine, glutamylcysteine, glutathione, and taurine in 29 patients with CRVO and 80 age- and gender-matched control subjects. Wilcoxon or Student’s t-test was used, when appropriate, to determine differences between groups. Multivariate logistic regression analysis was used to determine the risks for CRVO.

Results: CRVO patients showed significantly higher concentrations of cysteine (p = 0.032) and significantly lower concentrations of cysteinylglycine (p = 0.009) and taurine (p = 0.0002) than controls. Conversely, there were no significant differences in plasma homocysteine, glutamylcysteine, and glutathione between CRVO patients and controls. When categorized by CRVO type (ischemic/non-ischemic), taurine was still lower in both subgroups than in controls, whereas cysteine, cysteinylglycine, as well as homocysteine, were significantly higher only in the ischemic subgroup. In non-ischemic CRVO, cysteinylglycine fell just short of statistical significance (p = 0.06). Logistic regression analysis revealed an odds ratio of 1.02 (95% confidence interval (CI): 1.01–1.04, p = 0.001) for cysteine, 0.79 (95% CI: 0.70–0.89, p = 0.0002) for cysteinylglycine, and 0.94 (95% CI: 0.90–0.97, p = 0.002) for taurine.

Conclusions: Results suggest that reduced plasma levels of cysteinylglycine and taurine may contribute to the pathogenesis of both CRVO types. Furthermore, this study also demonstrated an association between ischemic CRVO and higher concentrations of homocysteine and cysteine.

KEYWORDS::

• Central retinal vein occlusion
• Laser-induced fluorescence capillary electrophoresis
• Homocysteine
• Cysteine
• Cysteinylglycine
• Glutamylcysteine
• Glutathione
• Taurine

ACKNOWLEDGMENTS

The authors have no financial interest in any material used in this study. The authors have received no support/funding to carry out this study. This paper was in part presented as a Scientific Poster at the 8th Euretina Annual Meeting, Vienna (Austria), 22–25 May 2008.

Declaration of interest: The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.