Figure 2: Urinary 8-OHdG/Cr before and after inhalation of true and placebo hydrogen gas for 4 weeks. Note: (A) Twenty Parkinson's disease (PD) patients. P value by Student's paired t-test is indicated. (B) Ten PD patients who inhaled hydrogen first. (C) Ten PD patients who inhaled placebo first. (B, C) No statistical significance by one-way analysis of variance. Date are expressed as the mean ± SE. 8-OHdG: 8-Hydroxy- 2′-deoxyguanine; Cr: creatine.