Background: Preterm infants are susceptible to "oxygen radical diseases" (ORD). 8-isoprostane (8-IP) is a bioactive eicosanoid generated by reactive oxygen species-catalyzed peroxidation of arachidonic acid. Malondialdehyde (MDA) is generated by the decomposition of oxidant-induced lipid hydroperoxides. We hypothesize that the development of ORD is associated with elevated plasma 8-IP on day 0-1, and increasing urine levels of MDA in the first month.
Methods: Preterm (<32 weeks, n = 39) and term (n = 39) infants were recruited at birth. Plasma 8-IP was quantified by ELISA on day 0-1, and urine MDA by colorimetric assay of thiobarbituric acid reactive substances (TBARS) on days 0-1, 7, 14, 21, and 28. ORD was defined as retinopathy of prematurity ≥ stage 1, pneumatosis, or oxygen requirement at 36 weeks corrected gestational age.
Results: Plasma 8-IP was higher on day 0-1 in preterm infants who developed ORD compared to term infants. Urine TBARS levels increased in preterm infants from day 0-1 to day 28 but were not different in infants with or without ORD. Preterm infants who developed ORD demonstrated a significant rise in urine TBARS levels from day 1 to 14.
Conclusions: Elevated plasma 8-IP on day 1 is associated with ORD in preterm infants. If validated as a biomarker for ORD, it may be useful in directing antioxidant therapies to the most susceptible infants. Urine TBARS during the first month are not significantly different in term infants, preterm infants with ORD, and preterm infants without ORD, but rapid rise of TBARS in the first 2 weeks may be associated with ORD.
Keywords: Prematurity; neonatal intensive care; oxidants; oxygen radical diseases; perinatal.