Measurement of urine 8-OHdG
Urine 8-OHdG content was measured by outsourcing the analysis to the Nikken Seil (Shizuoka, Japan). Briefly, urine 8-OHdG was quantified using an enzyme-linked immunosorbent assay kit for 8-OHdG (Nikken Seil), according to the manufacturer’s instructions. Measured urinary 8-OHdG levels were normalized to urinary creatinine concentrations and are shown as the urinary 8-OHdG (ng/mL)/creatinine (mg/mL) ratio.