PARABANIC ACID FOR MONITORING OF OXYGEN RADICAL ACTIVITY IN THE INJURED HUMAN BRAIN

THE authors used intracerebral microdialysis to harvest allantoin and parabanic acid, potential markers of in vivo oxygen radical activity, from the frontal lobe cortex of three patients in the neurointensive c are unit after serious aneurysmal subarachnoid haemorrhage. Clinical e vents involving severe secondary ischaemia, ultimately leading to stru ctural damage, were associated with a dramatic elevation of the microd ialysate level of parabanic acid, whereas allantoin showed less robust changes. In one patient with an uneventful clinical course and withou t signs of secondary ischaemia parabanic acid levels remained low. The results support the involvement of highly reactive oxygen radical spe cies in human cerebral ischaemia. Parabanic acid appears to be an impo rtant marker of free radical reactions in vivo and may be used to moni tor free radical activity and to evaluate pharmacological therapy with radical scavengers.