title: Surface film formation in vitro by infant and therapeutic surfactants: role of surfactant protein B.
abstract: BACKGROUND
  Pulmonary surfactant provides an alveolar surface-active film that is critical for normal lung function. Our objective was to determine in vitro film formation properties of therapeutic and infant surfactants and the influence of surfactant protein (SP)-B content.
  
  
  METHODS
  We used a multiwell fluorescent assay measuring maximum phospholipid surface accumulation (Max), phospholipid concentration required for half-maximal film formation (½Max), and time for maximal accumulation (tMax).
  
  
  RESULTS
  Among five therapeutic surfactants, calfactant (highest SP-B content) had film formation values similar to natural surfactant, and addition of SP-B to beractant (lowest SP-B) normalized its Max value. Addition of budesonide to calfactant did not adversely affect film formation. In tracheal aspirates of preterm infants with evolving chronic lung disease, SP-B content correlated with ½Max and tMax values, and SP-B supplementation of SP-B-deficient infant surfactant restored normal film formation. Reconstitution of normal surfactant indicated a role for both SP-B and SP-C in film formation.
  
  
  CONCLUSIONS
  Film formation in vitro differs among therapeutic surfactants and is highly dependent on SP-B content in infant surfactant. The results support a critical role of SP-B for promoting surface film formation.
authors.affiliation: Department of Pediatrics, University of California, San Francisco, San Francisco, California.
authors.forename: Olivier
authors.identifier: 0000000282083086
authors.initials: O
authors.lastname: Danhaive
authors.affiliation: Department of Pediatrics, University of California, San Francisco, San Francisco, California.
authors.forename: Cheryl
authors.initials: C
authors.lastname: Chapin
authors.affiliation: Department of Pediatrics, University of California, San Francisco, San Francisco, California.
authors.forename: Hart
authors.initials: H
authors.lastname: Horneman
authors.affiliation: Department of Cardiology, Bambino Gesù Children's Hospital, Rome, Italy.
authors.forename: Paola E
authors.initials: PE
authors.lastname: Cogo
authors.affiliation: Department of Pediatrics, University of California, San Francisco, San Francisco, California.
authors.forename: Philip L
authors.initials: PL
authors.lastname: Ballard
mesh_terms: D001688:Biological Products / Q000378:metabolism; D019819:Budesonide / Q000378:metabolism; D005453:Fluorescence; D006801:Humans; D066298:In Vitro Techniques; D007231:Infant, Newborn; D010743:Phospholipids / Q000378:metabolism* / Q000627:therapeutic use; D037701:Pulmonary Surfactant-Associated Protein B / Q000378:metabolism*; D011663:Pulmonary Surfactants / Q000378:metabolism* / Q000627:therapeutic use; D012127:Respiratory Distress Syndrome, Newborn / Q000517:prevention & control*
chemical_list: D001688:Biological Products; D010743:Phospholipids; D037701:Pulmonary Surfactant-Associated Protein B; D011663:Pulmonary Surfactants; D019819:Budesonide; C117342:calfactant; C072197:beractant