The effect of NBO on the production of 8-OHdG in cortex penumbra at 22.5 h reperfusion after 90-min ischemia. A) Representative photographs show the effect of NBO on the production of 8-OHdG in cortex penumbra. Bar = 20 μm. B) TTC staining. The black square indicates the location where the photograph taken from. C) Numbers of 8-OHdG-positive cell in the cortex penumbra. Values are expressed as mean ± SD, n = 5 each group. *P < 0.05 and **P < 0.01 vs. normoxic control.