title: Substrate utilization and kinetics of surfactant metabolism in evolving bronchopulmonary dysplasia.
abstract: OBJECTIVE
  To use stable isotopically labeled precursors of pulmonary surfactant phospholipids to measure precursor utilization and surfactant turnover in premature infants who required mechanical ventilation at birth, 2 weeks, and >4 weeks of age.
  
  
  METHODS
  Infants of < or =28 weeks' gestation received simultaneous 24-hour intravenous infusions of [1,2,3,4-13C4] palmitate and [1-13C1] acetate at birth, 2 weeks, and > or =4 weeks of life. Disaturated phospholipids were extracted from sequential tracheal aspirate samples obtained over a period of 2 weeks. Fractional catabolic rate (a measure of total turnover) and the fractional synthetic rates from plasma palmitate and de novo synthesis (acetate) were measured.
  
  
  RESULTS
  The fractional catabolic rate increased from 25.3% +/- 7.0% per day at birth to 53.8% +/- 14.4% per day at 4 weeks (P=.001). The combined contribution from plasma palmitate and de novo synthesis to total synthesis increased from 44.2% +/- 19.8% at birth to 85.2% +/- 32.8% at 4 weeks (P=.03).
  
  
  CONCLUSIONS
  Total surfactant turnover increased in premature infants with evolving bronchopulmonary dysplasia. The increasing contributions from acetate and plasma palmitate suggest a decrease in surfactant phospholipid recycling.
authors.affiliation: Division of Newborn Medicine, the Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, and St. Louis Children's Hospital, St Louis, Missouri 63110, USA.
authors.forename: Kimberly L
authors.initials: KL
authors.lastname: Spence
authors.forename: James C
authors.initials: JC
authors.lastname: Zozobrado
authors.forename: Bruce W
authors.initials: BW
authors.lastname: Patterson
authors.forename: Aaron
authors.initials: A
authors.lastname: Hamvas
mesh_terms: D019342:Acetic Acid / Q000378:metabolism*; D000367:Age Factors; D001997:Bronchopulmonary Dysplasia / Q000378:metabolism*; D002247:Carbon Isotopes; D005260:Female; D006801:Humans; D006819:Hyaline Membrane Disease / Q000378:metabolism*; D007223:Infant; D007231:Infant, Newborn; D007553:Isotope Labeling; D008297:Male; D019308:Palmitic Acid / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D037661:Pulmonary Surfactant-Associated Proteins / Q000378:metabolism*; D012720:Severity of Illness Index
chemical_list: D002247:Carbon Isotopes; D010743:Phospholipids; D037661:Pulmonary Surfactant-Associated Proteins; D019308:Palmitic Acid; D019342:Acetic Acid