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The Sources and Biochemical Characteristics of Cobalamin‐Binders in Human Amniotic Fluid *
Author(s) -
Nakamura Kousaku,
Sagawa Norimasa,
Mori Takahide
Publication year - 1993
Publication title -
asia‐oceania journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 50
eISSN - 1447-0756
pISSN - 0389-2328
DOI - 10.1111/j.1447-0756.1993.tb00393.x
Subject(s) - amniotic fluid , cobalamin , endocrinology , medicine , fetus , saliva , intrinsic factor , amnion , chemistry , biology , stomach , pregnancy , vitamin b12 , genetics
The sources and biochemical characteristics of cobalamin‐binders in amniotic fluid were investigated. Using gel‐permeation chromatography, cobalamin‐binder, extracted from amniotic fluid at term, was recovered in a single peak with the molecular size of haptocorrin. Neonatal saliva also contained only haptocorrin. However, neonatal gastric juice contained two types of cobalamin‐binders: haptocorrin and intrinsic factor. Amniotic fluid in midtrimester contained three types of cobalamin‐binders: haptocorrin, intrinsic factor, and transcobalamin II. The cultured amnion cells secreted mainly apo‐transcobalamin II. Concentrations of both apo‐haptocorrin and salivary amylase in amniotic fluid increased as gestation advanced. These results suggest that cobalamin‐binder in amniotic fluid in midtrimester originates from the fetal salivary gland, fetal gastric mucosa, and amnion cells, and that the contribution by the fetal salivary gland increases at term, when almost all cobalamin‐binders in amniotic fluid are haptocorrin.