Abstract
Amniotic fluid (AF) obtained from 17 pregnant women with gestational ages 20 to 45 weeks contained apos A-I (1.29 ± 0.59 mg/dl) and A-II (0.44 ± 0.28 mg/dl) by electroimmunoassay (EIA). The other known serum apolipoproteins Apo B, C-I, C-II, C-III, Apo D and Apo E were not detected by double diffusion analyses (DDA). Lecithin: sphingomyelin (L/S) ratios ranged from 1.6 to 7.0. All samples (n=4) with L/S ratios>5.0 were past term and were deficient in or had trace amounts of A-II by EIA. By DDA, A-I and A-II were absent from a premature infant's urine and a postmortem saline lavage of neonatal lung. Lung and placental tissues were negative for A-I and A-II by fluorescent antibody staining. Pooled AF (400 ml) was passed through an immunosorber specific for A-I. The retained fraction (R) reacted with anti-A-I and contained three major bands on basic polyacrylamide gel electrophoresis (PAGE) one of which had a mobility similar to A-I. After ultracentrifugation at density 1.23 g/ml, the unretained (U) fraction eluted as a single peak in the void volume (Ve) from sepharose-6B. Lipid analysis revealed lecithin, sphingomyelin, phosphatidyl inositol, triglyceride, cholesterol and cholesterol ester. By SDS PAGE analysis, the Ve peak contained 3 to 4 bands of m.w. 50-80,000 daltons and electron microscopy revealed homogenous spherical micelles with protein bubbles stained by phosphotungstic acid. We conclude that apolipoproteins A-I and A-II are present in amniotic fluid in addition to non-serum apolipoproteins which may have clinical significance for further studies on the composition of protein and lipid componants of surfactant in AF.
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McConathy, W., Blackett, P., Nordquist, R. et al. 197 APOLIPOPROTEINS (APOS) IN AMNIOTIC FLUID. Pediatr Res 12 (Suppl 4), 396 (1978). https://doi.org/10.1203/00006450-197804001-00202
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DOI: https://doi.org/10.1203/00006450-197804001-00202