Abnormalities in surfactant in sudden infant death syndrome as a postmortem marker and possible test of risk.
OBJECTIVE
To determine whether physical abnormalities in lung surfactant, particularly inversion of the hysteresis between surface tension and surface area, are an effective postmortem marker for sudden infant death syndrome (SIDS).


METHODS
Bronchoalveolar lavage (BAL) was employed to obtain lung rinsings from 55 infants under 24 months of age at autopsy, comprising 34 index cases and 21 controls. Folch reagent was used to extract the lipoid content which was then applied at two surface concentrations, fixed and BAL-determined (BALD), to the pool of a Langmuir trough in which surface tension (gamma) was measured continuously by the Wilhelmy method as surface area (A) was cycled.


RESULTS
The gamma:A loops from SIDS samples were inverted relative to controls (i.e. they were hysteresis reversed, this inversion being quantified by an empirical surface tension: area reversal (STAR) score). There was a wide scatter of STAR scores, but a critical value was found which offered a significant (P = 0.017) separation of SIDS cases from controls for a fixed surface concentration and a highly significant separation (P = 1.0 x 10(-4)) for BALD surface concentrations. Differences in the yields of phospholipid and proteolipid, or their correlation to STAR scores, did not reach statistical significance.


CONCLUSIONS
Inversion of the gamma :A loops (i.e. hysteresis inversion) would appear to offer a better postmortem marker of SIDS than any reported previously, the procedure having potential for development as a prospective test indicating the risk of this disease.
Hills
B A
BA
Paediatric Respiratory Research Centre, Mater Children's Hospital, Queensland, Australia.
Masters
I B
IB
Vance
J C
JC
Hills
Y C
YC
D001344:Autopsy; D015415:Biomarkers / Q000032:analysis; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry / Q000166:cytology*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008168:Lung / Q000502:physiology*; D008297:Male; D011663:Pulmonary Surfactants / Q000032:analysis*; D012307:Risk Factors; D013398:Sudden Infant Death / Q000453:epidemiology / Q000473:pathology; D013500:Surface Tension
D015415:Biomarkers; D011663:Pulmonary Surfactants