Rapid enzyme analysis of amniotic fluid phospholipids containing choline: a comparison with the lecithin to sphingomyelin ratio in prenatal assessment of fetal lung maturity

Planar chromatographic techniques in biomedicine: current status

In planar chromatography (PLC), the solvent flows through a layer either by means of capillary forces [conventional thin-layer chromatography (TLC)] or by a forced-flow system (over-pressured layer chromatography). Phases and instrumentation currently available are briefly examined. The main applications in biomedicine are reviewed. Although silica gel TLC plates still predominate, interest in other phases is increasing. Unique detection features such as immunostaining are emphasized. Although gas chromatography and high-performance liquid chromatography have superseded TLC in the analysis of carbohydrates, amino acids and indole derivatives, interest in PLC continues to be high in lipid analysis.

Combined enzymatic assay of phosphatidylglycerol and phosphatidylcholine in amniotic fluid

We present here a combined, quantitative enzymatic procedure for determining amniotic fluid phosphatidylglycerol and phosphatidylcholine and relate these findings to the assessment of fetal lung maturity. Under the assay conditions described phospholipase C specifically hydrolyses phosphatidylglycerol (PG) and phosphatidylcholine (PC) but not sphingomyelin, precluding the need for removal of sphingomyelin prior to analysis. Solvent extraction of the phospholipids from the amniotic fluid is, however, employed to avoid spurious elevation of PG and PC results by endogenous glycerol and choline. Of 45 amniocentesis fluids examined, 28 yielded detectable PG concentrations (greater than 0.5 mumol/l) and all but three of these exhibited PC concentrations in excess of 10 mumol/l. One case of respiratory distress occurred in an infant of 29 wk gestation with severe intrauterine growth retardation. Of the remaining 17 fluids in which PG was undetected enzymatically (less than or equal to 0.5 mumol/l), 14 also contained PC concentrations less than or equal to 10 mumol/l and all six cases of true respiratory distress syndrome came from within this sub-group. Strong correlations between the PC concentration and the lecithin:sphingomyelin ratio, r = 0.85 (p less than 0.001) and the PC and PG concentrations, r = 0.96 (p less than 0.001) were also found.