title: Digoxin- and digitoxin-like immunoreactive substances in amniotic fluid, cord blood, and serum of neonates.
abstract: Using four different digoxin kits, it was disclosed that the majority of various samples including amniotic fluid, cord blood, and serum from neonates contained substantial levels of digoxin-like immunoreactive substance. The differences in data seemed to be due to the range of epitopes which are recognized by antidigoxin antiserum. The day-to-day studies on sera serially obtained from infants at birth to 48 days old revealed that the level of the substance (0.31 +/- 0.12 ng/ml) in sera of the 1-day-old neonates rapidly declined to the level of 0.1 ng/ml by the 2nd postnatal wk and thereafter gradually declined. The immunological specificity and accuracy of the detection of digoxin-like immunoreactive substance was confirmed by a sample dilution test, a recovery test for standard digoxin, and an absorption test with antidigoxin antiserum. The amniotic fluid and cord blood also contained four to eight times more of a digitoxin-like immunoreactive substance than they did digoxin-like immunoreactive substance. A significant correlation was observed between the levels of digoxin-like immunoreactive substance and of digitoxin-like immunoreactive substance (p less than 0.01).
mesh_terms: D000653:Amniotic Fluid / Q000378:metabolism*; D004074:Digitoxin / Q000097:blood / Q000378:metabolism*; D004077:Digoxin / Q000097:blood / Q000378:metabolism*; D005312:Fetal Blood / Q000032:analysis*; D006801:Humans; D007124:Immunoenzyme Techniques; D007231:Infant, Newborn; D011863:Radioimmunoassay
chemical_list: D004077:Digoxin; D004074:Digitoxin