title: Partial volume rat lung irradiation: the protective/mitigating effects of Eukarion-189, a superoxide dismutase-catalase mimetic.
abstract: OBJECTIVE
  The purpose of the current study was to elucidate the protective/mitigating effects of a SOD-catalase mimetic, Eukarion-189 (EUK-189), on DNA damage in rat lung following irradiation. The particular focus of these studies was the efficacy of EUK-189 when given after irradiation (mitigation).
  
  
  METHODS
  We exposed whole or lower lungs of female Sprague-Dawley rats to doses ranging from 10 to 20.5 Gray (Gy) of (60)Co gamma rays. Animals in the EUK-189 treated groups received 2 or 30 mg/kg intraperitoneally (i.p.) at various times postirradiation (PI). A micronucleus assay was used to examine DNA damage at various times up to 16 weeks PI.
  
  
  RESULTS
  Our results indicated that EUK-189 administration after irradiation is effective at reducing micronucleus formation in lung fibroblasts at various times following radiation exposure. Treatment with EUK-189 in the first 3 days after thoracic irradiation did not, however, modify the dose required to cause severe morbidity at 2-3 months after irradiation.
  
  
  CONCLUSIONS
  The protection produced when Eukarion-189 was given shortly after irradiation suggests that DNA damage observed in the lung may be caused by chronic production of ROS induced by a chronic inflammatory response initiated by the radiation treatment. We speculate that our failure to observe protection against severe morbidity at 2-3 months may be because our treatment regime only blocked the initial wave of ROS production and that treatment needs to be more prolonged to suppress the effects of a chronic inflammatory response.
authors: Research Division, Ontario Cancer Institute, Princess Margaret Hospital, University Health Network, Toronto, Ont., Canada.
authors: Aimée R
authors: AR
authors: Langan
authors: Mohammed A
authors: MA
authors: Khan
authors: Ivan W T
authors: IW
authors: Yeung
authors: Jake
authors: J
authors: Van Dyk
authors: Richard P
authors: RP
authors: Hill