title: Assessment of nitrosative stress and lipid peroxidation activity in asymptomatic exposures to medical radiation: The bystander effect of ionizing radiation.
abstract: BACKGROUND
  Adaptive response and bystander effect are two important phenomena involved in biological responses to ionizing radiation.
  
  
  OBJECTIVE
  To determine the bystander effect of ionizing radiation in medical exposures by measuring the serum nitric oxide (NO•), peroxynitrite (ONOO•), and malondialdehyde (MDA) levels.
  
  
  METHODS
  Twenty-five medical staff working in the Unit of Radiology and 15 medical staff working in other departments at the Al-Yarmouk teaching hospital in Baghdad, Iraq, were enrolled in the study. Venous blood was obtained from each subject for determination of NO•, ONOO•, and MDA levels.
  
  
  RESULTS
  Significantly higher serum NO•, ONOO•, and MDA levels were observed in participants working in the radiology unit as compared with serum levels in those working elsewhere. There was no correlation between the lipid peroxidation activity and ONOO•/NO• ratio. The serum NO• level in subjects working in the x-ray services was significantly higher than that in subjects working in the CT and MRI services.
  
  
  CONCLUSIONS
  The bystander effect of radiation could be observed in asymptomatic individuals working in the radiology unit and it was particularly well observed in people working in the X-ray services as opposed to CT and MRI services. Determination of serum nitrogen species could be a useful laboratory investigation for assessment of the bystander effect of radiation.
authors.affiliation: Department of Pharmacology, Medical Physics, College of Medicine, Al-Mustansiriya University, Baghdad, Iraq.
authors.forename: Marwan S M
authors.initials: MS
authors.lastname: Al-Nimer
authors.forename: Nida H
authors.initials: NH
authors.lastname: Ali
keywords: Ionizing radiation; malondialdehyde; nitrogen species