Evaluation of urinary hydrogen peroxide as an oxidative stress biomarker in a healthy Japanese population

The usefulness of urinary hydrogen peroxide (H2O2) as an oxidative stress biomarker was evaluated in 766 healthy Japanese. The mean level of urinary concentrations of H2O2 was 5.66 +/- 8.27 mu mol/g creatinine, and was significantly higher in females than in males. Significant correlations of H2O2 were observed with age, aspartate aminotransferase (AST), alanine aminotransferase (ALT), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), insulin, 8-hydroxy-2'-deoxyguanosine (8-OHdG), and exercise habit in females. In both sexes, H2O2 showed a significant correlation with 8-OHdG. By a multiple logistic regression analysis, urinary H2O2 was positively associated with urinary 8-OHdG and TC and was inversely associated with insulin. By stratification of sex and age, the association of urinary H2O2 with TC was positive in both sexes under 50 years old and was inverse in males over 50 years old, and that with insulin was inverse in males over 50 years old and in females under 50 years old. Moreover, by stratification of sex and age, a positive association of H2O2 with exercise and an inverse association of H2O2 with alcohol consumption became clear in males under 50 years old, although there were no significant odds for H2O2 after adjustment for covariates. In conclusion, the present results suggest that urinary H2O2 is a useful biomarker for oxidative stress, showing an association with 8-OHdG, TC, and insulin independently

Senescence in cell oxidative status in two bird species with contrasting life expectancy.

Oxidative stress occurs when the production of reactive oxygen species (ROS) by an organism exceeds its capacity to mitigate the damaging effects of the ROS. Consequently, oxidative stress hypotheses of ageing argue that a decline in fecundity and an increase in the likelihood of death with advancing age reported at the organism level are driven by gradual disruption of the oxidative balance at the cellular level. Here, we measured erythrocyte resistance to oxidative stress in the same individuals over several years in two free-living bird species with contrasting life expectancy, the great tit (known maximum life expectancy is 15.4 years) and the Alpine swift (26 years). In both species, we found evidence for senescence in cell resistance to oxidative stress, with patterns of senescence becoming apparent as subjects get older. In the Alpine swift, there was also evidence for positive selection on cell resistance to oxidative stress, the more resistant subjects being longer lived. The present findings of inter-individual selection and intra-individual deterioration in cell oxidative status at old age in free-living animals support a role for oxidative stress in the ageing of wild animals