title: Ontogeny of methionine utilization and splanchnic uptake in critically ill children.
abstract: To determine the rates of methionine splanchnic uptake and utilization in critically ill pediatric patients we used two kinetic models: the plasma methionine enrichment and the "intracellular" homocysteine enrichment. Twenty four patients, eight infants, eight children, and eight adolescents, were studied. They received simultaneous, primed, constant, intravenous infusions of l-[(2)H(3)]methylmethionine and enteral l-[1-(13)C]methionine. The ratio of [(13)C]homocysteine to [(13)C]methionine enrichment was 1.0 ± 0.15, 0.80 ± 0.20, and 0.66 ± 0.10, respectively, for the infants, children, and adolescents, and it was different between the infants and adolescents (P < 0.01). Methionine splanchnic uptake was 63, 45, and 36%, respectively, in the infants, children, and adolescents, and it was higher (P < 0.01) in the infants compared with the adolescents. The infants utilized 73% of methionine flux for nonoxidative disposal, while 27% was used for transulfuration (P < 0.001). Conversely, in the adolescents, 40% was utilized for nonoxidative disposal, while 60% was used for transulfuration. There is ontogeny on the rates of methionine splanchnic uptake and on the fate of methionine utilization in critically ill children, with greater methionine utilization for synthesis of proteins and methionine-derived compounds (P < 0.01) and decreased transulfuration rates in the infants (P < 0.01), while the opposite was observed in the adolescents. The plasma model underestimated methionine kinetics in children and adolescents but not in the infants, suggesting lesser dilution and greater compartmentation of methionine metabolism in the infant population. All patients were in negative methionine balance, indicating that the current enteral nutritional support is inadequate in these patients.
authors.affiliation: Texas Children's Hospital, Children's Nutrition Research Center, USDA/ARS at Baylor College Medicine, 1100 Bates St., Houston, TX 77030, USA.
authors.forename: Sascha
authors.initials: S
authors.lastname: Verbruggen
authors.forename: Jama
authors.initials: J
authors.lastname: Sy
authors.forename: William E
authors.initials: WE
authors.lastname: Gordon
authors.forename: Jean
authors.initials: J
authors.lastname: Hsu
authors.forename: Manhong
authors.initials: M
authors.lastname: Wu
authors.forename: Shaji
authors.initials: S
authors.lastname: Chacko
authors.forename: David
authors.initials: D
authors.lastname: Zurakowski
authors.forename: Douglas
authors.initials: D
authors.lastname: Burrin
authors.forename: Leticia
authors.initials: L
authors.lastname: Castillo
mesh_terms: D000005:Abdomen / Q000502:physiology*; D000293:Adolescent; D000375:Aging / Q000378:metabolism; D000465:Algorithms; D002245:Carbon Dioxide / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D016638:Critical Illness; D004032:Diet; D004750:Enteral Nutrition; D005260:Female; D006710:Homocysteine / Q000378:metabolism; D006801:Humans; D007223:Infant; D007553:Isotope Labeling; D007700:Kinetics; D008297:Male; D008715:Methionine / Q000378:metabolism* / Q000493:pharmacokinetics; D010084:Oxidation-Reduction
chemical_list: D006710:Homocysteine; D002245:Carbon Dioxide; D008715:Methionine