Patients with cystic fibrosis (CF) may be more susceptible to oxidative cell injury than normal healthy children due to both the impaired absorption of antioxidant nutrients and the increased oxidative stress caused by chronic pulmonary infections. The purpose of this study was to examine whether markers of oxidative damage to lipids (malondialdehyde-like substances and lipid hydroperoxides) and proteins (protein carbonyls) were present in the plasma of CF patients. Mean values (? SD) of thiobarbituric acid-reactive substances were significantly higher in patients (6.93 & 1.47 prnol/L, n = 25) than in controls (5.84 2 0.59 ~mol/L,; n = 10). FFA hydroperoxides were not detected in control subjects (the detection limit of the assay was 0.02 pmol/L), but in 11 of the 33 CF patients studied they were found in a range of 0.03-0.34 pmoVL. Plasma protein carbonyl concentrations did not differ significantly between the two groups @ = 0.076), although a much wider distribution was observed in the CF patients (range 0.17-5.64 nmollmg protein) than in the control group (range 0.24-1.55 nmollmg protein). No correlation was found between thiobarbituric acid-reactive substances and FFA

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ABSTRACT. Plasma antioxidant status and total radicaltrapping antioxidant potential ( T R A P ) o f children ( n =24