Lamellar body count as a predictor of neonatal respiratory distress syndrome in preterm premature rupture of membranes

Background: Lamellar bodies are present in amniotic fluid and their quantity increases with increased gestational age. Preterm premature rupture of the membranes (P-PROM) is one of the most common complications of pregnancy and is a major cause of preterm deliveries and thus the important cause of RDS. Fetal pulmonary maturity can be assessed by direct or indirect measurement of surfactant phospholipids secreted by the fetal lungs into amniotic fluid. Lamellar body count (LBC) has been introduced as an alternative to other methods.Methods: The study’s prime aim is to establish LBC as a predictor of RDS in P-PROM. We included pregnant women with P-PROM and gestational age between 28 weeks and 37 weeks and singleton live pregnancy. The lamellar body counting from amniotic fluid was done with the use of a standard hematology cell counter, sysmex KX-21. There was statistically significant co-relation between lamellar body count and period of gestation (by applying ANOVA).Results: Lamellar body counts were significantly less in cases of RDS as compared to non RDS cases.Conclusions: LBC count was selected among all other tests because the test can be performed with equipment found in most clinical analysis laboratories and is reliable in predicting fetal lung maturity.

Surfactant protein B inhibits secretory phospholipase A2 hydrolysis of surfactant phospholipids

Hydrolysis of surfactant phospholipids (PL) by secretory phospholipases A2 (sPLA2) contributes to surfactant damage in inflammatory airway diseases such as acute lung injury/acute respiratory distress syndrome. We and others have reported that each sPLA2 exhibits specificity in hydrolyzing different PLs in pulmonary surfactant and that the presence of hydrophilic surfactant protein A (SP-A) alters sPLA2-mediated hydrolysis. This report tests the hypothesis that hydrophobic SP-B also inhibits sPLA2-mediated surfactant hydrolysis. Three surfactant preparations were used containing varied amounts of SP-B and radiolabeled tracers of phosphatidylcholine (PC) or phosphatidylglycerol (PG): 1) washed ovine surfactant (OS) (pre- and postorganic extraction) compared with Survanta (protein poor), 2) Survanta supplemented with purified bovine SP-B (1–5%, wt/wt), and 3) a mixture of dipalmitoylphosphatidylcholine (DPPC), 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC), and 1-palmitoyl-2-oleoyl-phosphatidylglycerol (POPG) (DPPC:POPC:POPG, 40:40:20) prepared as vesicles and monomolecular films in the presence or absence of SP-B. Hydrolysis of PG and PC by Group IB sPLA2 (PLA2G1A) was significantly lower in the extracted OS, which contains SP-B, compared with Survanta ( P = 0.005), which is SP-B poor. Hydrolysis of PG and PC in nonextracted OS, which contains all SPs, was lower than both Survanta and extracted OS. When Survanta was supplemented with 1% SP-B, PG and PC hydrolysis by PLA2G1B was significantly lower ( P < 0.001) than in Survanta alone. When supplemented into pure lipid vesicles and monomolecular films composed of PG and PC mixtures, SP-B also inhibited hydrolysis by both PLA2G1B and Group IIA sPLA2 (PLA2G2A). In films, PLA2G1B hydrolyzed surfactant PL monolayers at surface pressures ≤30 mN/m ( P < 0.01), and SP-B lowered the surface pressure range at which hydrolysis can occur. These results suggest the hydrophobic SP, SP-B, protects alveolar surfactant PL from hydrolysis mediated by multiple sPLA2 in both vesicles (alveolar subphase) and monomolecular films (air-liquid interface).