The usefulness of urinary hydrogen peroxide (H(2)O(2)) as an oxidative stress biomarker was evaluated in 766 healthy Japanese. The mean level of urinary concentrations of H(2)O(2) was 5.66 ± 8.27 μmol/g creatinine, and was significantly higher in females than in males. Significant correlations of H(2)O(2) 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, H(2)O(2) showed a significant correlation with 8-OHdG. By a multiple logistic regression analysis, urinary H(2)O(2) 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 H(2)O(2) 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 H(2)O(2) with exercise and an inverse association of H(2)O(2) with alcohol consumption became clear in males under 50 years old, although there were no significant odds for H(2)O(2) after adjustment for covariates. In conclusion, the present results suggest that urinary H(2)O(2) is a useful biomarker for oxidative stress, showing an association with 8-OHdG, TC, and insulin independently.

The associations of serum arginase I with serum L-arginine, serum 3-nitrotyrosine, and fractional exhaled nitric oxide (FENO) were evaluated cross-sectionally in healthy Japanese workers. The serum median (minimum-maximum) levels of arginase I, 3-nitrotyrosine, and FENO in healthy people (n = 130) were 14.6 (0.94-108.1) ng/mL, 81.0 (0.27-298.6) pmol/mg protein, and 14.0 (5.0-110.0) parts per billion, respectively. Significant correlations of arginase I with FENO, L-arginine, 3-nitrotyrosine, and percent predicted forced expiratory volume in 1 s (FEV1 (% predicted)) were observed, and correlations of FENO with immunoglobulin E (IgE), NOx, arginase I, and sex and allergy were also observed. By multiple regression analysis, arginase I showed positive associations with FENO and 3-nitrotyrosine, and a negative association with L-arginine; and FENO showed positive associations with IgE and NO2(-) + NO3(-) (NOx), and a negative association with L-arginine, as well as an association with sex. Moreover, logistic regression analysis showed linear inverse associations of arginase I and 3-nitrotyrosine with L-arginine, and showed linear positive associations of FENO with IgE and NOx. It was concluded that serum arginase I might regulate serum L-arginine and 3-nitrotyrosine via L-arginine, and that IgE or NOx might regulate FENO in a healthy Japanese population.