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SE Moriarty, JH Shah, S Jiang, M Lynn, K Openo, DP Jones, P Sternberg; Evaluation of Blood Plasma Redox Status in Smokers Versus Nonsmokers as a Potential Indicator of ARMD Susceptibility . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2821.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To measure blood plasma redox status in smokers versus nonsmokers. Smoking is a risk factor for ARMD and ARMD is thought to be due to oxidative stress, therefore, evaluation of blood plasma redox could be a potential indicator of ARMD susceptibility. Method: Measurements of plasma cysteine (Cys) and cystine (CySS) were obtained from volunteer smokers and nonsmokers between the ages of 50-75 years (n=44 nonsmokers, n=41 smokers). Blood samples were collected into a heparinzed butterfly syringe, and were then transferred to a redox preservation solution. This procedure enables quantitative recovery of Cys/Cyss and minimizes variance in Cys/Cyss ratios between sampling and acidification time. The redox potentials (Eh) of the different thiol/disulfide pools were calculated using the Nernst equation, Eh=Eo + RT/nF(ln[Cyss]/[Cys]2), where Eo is the standard potential for the redox couple, R is the gas constant, T is the absolute temperature, n is 2 for the number of electrons transferred, and F is Faraday's constant. The standard potential Eo for the 2 Cys/Cyss couple at pH 7.4 is -250 mV. (Jones et al, 1998). Results: The blood plasma redox status in smokers was -79.5± 8.7mv, which was significantly more oxidized compared to nonsmokers, which was -67.1±16.0mv(p value <0.001). The age range for the two groups was 50-67 years (mean for nonsmokers: 57.6, mean for smokers: 57.8). Conclusion: Smokers demonstrate a significantly more oxidized blood plasma redox status than nonsmokers, suggesting that tissues in smokers, including the retina and RPE, may be subjected to greater oxidative stress. The RPE, already under high oxidative stress due to focused light, high oxygen concentration, and lipid peroxidation, may be even more sensitive to a shift in redox caused by smoking. This extra oxidative stress may contribute to the onset and progression of age-related macular degeneration (ARMD) and be a factor in the link between smoking and increased risk of ARMD. Blood plasma redox status may also be a good marker for ARMD susceptibility.
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