title: Surfactant protein B amount and kinetics in newborn infants: an optimized procedure.
abstract: Surfactant protein B (SP-B) plays a key role in surfactant homeostasis affecting its biophysical properties and physiological function. Recently, a method to measure SP-B amount and kinetics from tracheal aspirates (TAs) became available. The main objective of this study was to improve the critical steps of the procedure to obtain a better SP-B sensitivity. We administered a 24 h continuous infusion of 1 mg/kg/h of 1(13)C-leucine to ten newborn infants. SP-B was isolated from serial TAs and its fractional synthesis rate, secretion time, peak time and half life were derived from (13)C enrichment curves obtained by gas chromatography mass spectrometry. SP-B amount in TAs was also assessed. During the extraction step, acidification and organic solvent ratio optimization doubled the recovery of SP-B from TAs, so did the elongation of the propylation time (from 20 min to 1 h) with enhanced leucine derivatization yield. Measurement of (13)C leucine enrichments, and therefore all SP-B kinetics parameters, were successfully calculated in all TAs samples due to the increase of SP-B yield. SP-B amount was 0.29 (0.16-0.41) % of total phospholipids with a minimum value of 0.08% belonging to one of the respiratory distress syndrome (RDS) patients. In conclusion, this new procedure enables accurate determination of SP-B kinetics even in the presence of low protein amount like in preterm RDS patients.
authors.affiliation: Department of Medicine, Anaesthesia and Critical Care, University of Padova, Padova, Italy. lab2@pediatria.unipd.it
authors.forename: Manuela
authors.initials: M
authors.lastname: Simonato
authors.forename: Aldo
authors.initials: A
authors.lastname: Baritussio
authors.forename: Luca
authors.initials: L
authors.lastname: Vedovelli
authors.forename: Giulia
authors.initials: G
authors.lastname: Lamonica
authors.forename: Virgilio Paolo
authors.initials: VP
authors.lastname: Carnielli
authors.forename: Paola Elisa
authors.initials: PE
authors.lastname: Cogo
mesh_terms: D012634:Bodily Secretions / Q000737:chemistry / Q000378:metabolism; D002247:Carbon Isotopes; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn / Q000378:metabolism*; D007700:Kinetics; D007930:Leucine / Q000008:administration & dosage / Q000493:pharmacokinetics; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D010743:Phospholipids / Q000032:analysis / Q000378:metabolism; D011498:Protein Precursors / Q000032:analysis* / Q000378:metabolism; D011510:Proteolipids / Q000032:analysis* / Q000378:metabolism; D014132:Trachea / Q000378:metabolism
chemical_list: D002247:Carbon Isotopes; D010743:Phospholipids; D011498:Protein Precursors; D011510:Proteolipids; C105511:surfactant protein B propeptide; D007930:Leucine