The evaluation of oxidative DNA damage in children with brain damage using 8-hydroxydeoxyguanosine levels

Urinary and cerebrospinal fluid (CSF) levels of 8-hydroxydeoxyguanosine (8-OHdG) were examined to estimate the relevance of oxidative stress in children with brain damage. Urinary 8-OHdG levels were measured in 51 children with various forms of central nervous system (CNS) disorders (status epilepticus [SE], hypoxic-ischemic encephalopathy [HIE], CNS infections and chronic epilepsy) and these levels were compared with those in 51 healthy children. CSF 8-OHdG levels were measured in 25 children with brain damage and in 19 control subjects. In addition, urinary and CSF levels of 8-OHdG were compared between the children with brain damage and healthy children. Finally, the relationship between urinary and CSF levels of 8-OHdG was determined in 12 children that provided both urinary and CSF samples. Our results showed that urinary 8-OHdG levels in children with HIE and CNS infections were higher than those of controls (Steel test; p < 0.05 and p < 0.05, respectively) and that CSF 8-OHdG levels were higher in children with SE, HIE, and CNS infections than in control subjects (Steel test; p < 0.01, 0.05 and 0.05, respectively). In addition, a positive correlation between the levels of urinary and CSF 8-OHdG was noted in the 12 children that provided both CSF and urinary samples (Spearman's rank correlation; rho = 0.82, p < 0.01). Further, we observed changes in the urinary 8-OHdG in a patient with HHV-6 encephalopathy, and found that the changes correlated well with the patient's clinical condition. These results suggest that oxidative stress is strongly related to acute brain damage in children, and that 8-OHdG is a useful marker of brain damage. Therefore, repeated measurements of urinary 8-OHdG may be helpful in estimating the extent of brain damage.