Urinary excretion of the nitrotyrosine metabolite 3-nitro-4-hydroxyphenylacetic acid in preterm and term infants.

Background: Newborn infants are exposed to various sources of oxidative and/or nitrative stress, which refers to either oxidation and/or nitration of endogenous proteins including loss of their original function. Nitrative stress is predominantly caused following synthesis of peroxynitrite. Particularly preterm infants with immature defense mechanisms against free radical injury appear at risk.