Conjugated 1β-Hydroxycholic Acid in the Urine of Newborns and Pregnant Women Measured by Radioimmunoassay Using Antisera Raised against N-(1β-Hydroxycholyl)-2-aminopropionic Acid-Bovine Serum Albumin Conjugate

Abstract

Anti-tauro 1β-hydroxycholic acid antisera were prepared by immunizing rabbits with N-(1β, 3α, 7α, 12α-tetrahydroxy-5β-cholan-24-oyl)-2-aminopropionic acid-bovine serum albumin (BSA) conjugate. The antisera raised had high affinity (1.25-1.46×10⁹ M^-1) and specificity for conjugated 1β-hydroxycholic acid; cross-reactivity for glyco 1β-hydroxycholic acid was 100% and that for the glycine and taurine conjugates of other 1β-hydroxylated bile acids ranged from 11.30 to 0.23%. Urinary concentrations of conjugated 1β-hydroxycholic acid were determined by radioimmunoassay in newborns, 0-20 d after birth, in amounts ranging from 0.29 to 18.51 μg/ml and in women in late pregnancy (<1.13 μg/ml), as well as in normal women (<0.12 μg/ml).