title: A dual stable isotope tracer method for the measurement of surfactant disaturated-phosphatidylcholine net synthesis in infants with congenital diaphragmatic hernia.
abstract: The aim of the study was to measure for the first time in humans surfactant disaturated-phosphatidylcholine (DSPC) net synthesis and kinetics by using a novel, dual stable isotope tracer approach. Ten infants with congenital diaphragmatic hernia [CDH; birth weight, 3.4 +/- 0.2; gestational age, 39.8 +/- 0.4 wk] and 6 age-matched control subjects with no lung disease (birth weight, 3.2 +/- 0.3 kg; gestational age, 39.1 +/- 1.1 wk), all of whom were admitted to the neonatal intensive care unit (Padua, Italy), were studied. All infants received simultaneously an intratracheal (carbon-13 di-palmitoyl-phosphatidylcholine) and an i.v. (deuterated palmitic acid) stable isotope tracer. Isotopic enrichment curves of DSPC from sequential tracheal aspirates were analyzed by mass spectrometry. DSPC kinetic data were expressed as mean +/- SEM and compared by the Mann-Whitney test. DSPC net synthesis from plasma palmitate was nearly identical in infants with CDH and control subjects (8.6 +/- 2.2 and 8.1 +/- 1.5 mg. kg(-1). d(-1); P = 0.7). DSPC apparent pool size was 36.7 +/- 7.5 and 58.5 +/- 9.1 mg/kg (P = 0.07) and half-life was 26.7 +/- 4.5 and 50.3 +/- 9.7 h (P = 0.03) in infants with CDH and control subjects, respectively. Both DSPC turnover and percentage of catabolism/recycling significantly correlated with duration of mechanical ventilation. In conclusion, the measurements of net DSPC synthesis and catabolism/recycling were reported for the first time in humans. Mean net DSPC synthesis was approximately 8 mg. kg(-1). d(-1). No significant differences were found between control subjects and infants with CDH. DSPC turnover was faster in infants with CDH, presumably reflecting an increased DSPC catabolism/recycling. Whether this may ultimately lead to a secondary surfactant deficiency in infants with CDH is still to be ascertained.
authors.affiliation: Department of Pediatrics, University of Padua, Via Giustiniani 3, 35128 Padua, Italy. cogo@pediatria.unipd.it
authors.forename: Paola E
authors.initials: PE
authors.lastname: Cogo
authors.forename: Luc J I
authors.initials: LJ
authors.lastname: Zimmermann
authors.forename: Giovanna
authors.initials: G
authors.lastname: Verlato
authors.forename: Paola
authors.initials: P
authors.lastname: Midrio
authors.forename: Antonella
authors.initials: A
authors.lastname: Gucciardi
authors.forename: Carlo
authors.initials: C
authors.lastname: Ori
authors.forename: Virgilio P
authors.initials: VP
authors.lastname: Carnielli
mesh_terms: D000818:Animals; D002250:Carbon Radioisotopes / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D005865:Gestational Age; D006548:Hernia, Diaphragmatic / Q000378:metabolism*; D065630:Hernias, Diaphragmatic, Congenital; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D010713:Phosphatidylcholines / Q000737:chemistry / Q000378:metabolism; D011247:Pregnancy; D011663:Pulmonary Surfactants / Q000737:chemistry / Q000378:metabolism; D011849:Radioactive Tracers; D013223:Statistics as Topic
chemical_list: D002250:Carbon Radioisotopes; D010713:Phosphatidylcholines; D011663:Pulmonary Surfactants; D011849:Radioactive Tracers