Enzymatic measurement of phosphatidylglycerol in amniotic fluid.
We describe an enzymatic method for measuring phosphatidylglycerol (PG) at concentrations as low as 0.2 mumol/L in amniotic fluid. Amniotic fluid (1.5 mL) is centrifuged at 10,000g for 20 min to obtain a lamellar body pellet, which is reconstituted with 0.5 mL of buffer. The PG is measured by a two-step enzymatic scheme. Recovery studies demonstrated that the pellet contains > 97% of the PG present in amniotic fluid. Between-run CVs were 28%, 5.7%, and 2.6% for amniotic fluid controls with means of 0.32, 3.9, and 10.7 mumol/L, respectively (n = 20). The enzymatic procedure was not significantly affected by blood, meconium, bilirubin, or other phospholipids. Lecithin/sphingomyelin ratio (n = 101) and fluorescence polarization (n = 127) compared with log(PG) showed correlation coefficients of 0.832 and -0.866, respectively. This test's ability to detect low concentrations of PG in amniotic fluid may make it a better predictor of fetal lung immaturity than previous methods.
Jones
G W
GW
Department of Pathology, University of Utah, School of Medicine, Salt Lake City 84132.
Ashwood
E R
ER
D000653:Amniotic Fluid / Q000737:chemistry*; D000675:Ampyrone / Q000378:metabolism; D002863:Chromogenic Compounds; D005260:Female; D005325:Fetal Organ Maturity; D005454:Fluorescence Polarization; D005991:Glycerol Kinase / Q000378:metabolism; D005993:Glycerolphosphate Dehydrogenase / Q000378:metabolism; D006801:Humans; D008168:Lung / Q000196:embryology*; D008832:Microchemistry; D010084:Oxidation-Reduction; D010713:Phosphatidylcholines / Q000032:analysis; D010715:Phosphatidylglycerols / Q000032:analysis*; D010739:Phospholipase D / Q000378:metabolism; D011247:Pregnancy; D012680:Sensitivity and Specificity; D013109:Sphingomyelins / Q000032:analysis
D002863:Chromogenic Compounds; D010713:Phosphatidylcholines; D010715:Phosphatidylglycerols; D013109:Sphingomyelins; D000675:Ampyrone; D005993:Glycerolphosphate Dehydrogenase; C036140:L-alpha-glycerol-phosphate oxidase; D005991:Glycerol Kinase; D010739:Phospholipase D