title: Postnatal gender-dependent maturation of cellular cysteine uptake.
abstract: BACKGROUND
  In view of the functional capacity of glutathione synthesis in premature infants, and because the availability of cysteine is one the rate limiting steps in glutathione synthesis, we hypothesized that the low glutathione levels in premature infants may be due to immaturity of the active cellular uptake of cysteine.
  
  
  OBJECTIVE
  To document in cells from newborn infants the effect of maturity and gender on cysteine uptake and consequently on glutathione levels.
  
  
  METHODS
  Incorporation of L-[35S] cysteine was measured in leukocytes from cord blood and from tracheal aspirates (TAC) of newborn infants of varying (gestational as well as postnatal) ages and gender. Cysteine uptake was correlated with glutathione in TAC.
  
  
  RESULTS
  The maturity of newborn girls positively influences cysteine uptake, which is responsible for 78% of the variation in their glutathione content. However, in newborn boys, gestational and postnatal ages did not influence the cysteine uptake.
  
  
  CONCLUSIONS
  Cysteine uptake appears to be the limiting step explaining the reported gender-related differences in glutathione as well as the low levels of this central antioxidant found in premature infants. The immature cysteine uptake found in cells from premature infants raises questions about the bioavailability of this conditionally essential amino acid in regimens of parenteral nutrition for human neonates.
authors.affiliation: Research Centre and Neonatal Service, Hĵpital Ste-Justine, Montreal, Que, Canada. jclavoie@justine.umontreal.ca
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Lavoie
authors.forename: Thérèse
authors.initials: T
authors.lastname: Rouleau
authors.forename: Anita C
authors.initials: AC
authors.lastname: Truttmann
authors.forename: Philippe
authors.initials: P
authors.lastname: Chessex
mesh_terms: D000367:Age Factors; D000975:Antioxidants / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism* / Q000493:pharmacokinetics*; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D005865:Gestational Age; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D012737:Sex Factors; D013997:Time Factors; D014132:Trachea / Q000378:metabolism
chemical_list: D000975:Antioxidants; D005978:Glutathione; D003545:Cysteine