Protein carbonyls and lipid peroxidation products as oxidation markers in preterm infant plasma: Associations with chronic lung disease and retinopathy and effects of selenium supplementation

The purpose of this study was to determine whether protein carbonyls and th e lipid peroxidation product malondialdehyde (MDA) are elevated in plasma f rom very low birth weight (<1500 g) infants, whether they are affected by s elenium supplementation, and whether they are associated with poor respirat ory outcome or retinopathy. The study group comprised 173 infants enrolled in a randomized controlled trial of selenium supplementation. Plasma sample s, collected before randomization, at 7 and 28 d after birth, and at 36 wk postmenstrual age, were analyzed for protein carbonyls and total MDA. Respi ratory outcome was assessed as oxygen requirement at 28 d of age or 36 wk p ostmenstrual age and as number of days on oxygen; Protein carbonyl concentr ations in very low birth weight infants were significantly higher than for adults but lower than for cord blood from term infants. Median values decre ased significantly by 28 d, and there was no relationship with birth weight . MDA concentrations in very low birth weight infants overlapped the ranges for healthy adults and cord blood from term infants. They correlated posit ively with birth weight at 28 d but not at other times. Supplementation alm ost doubled plasma selenium concentrations, but carbonyls and MDA did not d iffer between the supplemented and unsupplemented groups. There were no sig nificant differences in oxidant marker levels in infants who did or did not develop chronic lung disease or retinopathy. Protein carbonyls and MDA mea surements in plasma do not show evidence of systemic oxidative stress in <1 500-g infants and are not affected by selenium supplementation. Oxidative i njury at sites such as the lung may be important in prematurity, but marker s from such sites must be measured to relate to outcome and antioxidant sup plementation.