Fetal uptake

Hood, R.D., G.C. Vedel-Macrander, M.J. Zaworotko, F.M. Tatum, and R.G. Meeks. 1987. Distribution, metabolism, and fetal uptake of pentavalent arsenic in pregnant mice following oral or intraperitoneal administration. Teratology 35 19-25. 

Calbindin-D9k has been identified in both the placenta and yolk sac of rats and mice, and increases in the later stages of gestation when there is considerable fetal uptake of calcium for mineralization of the skeleton. In both birds and mammals, calcitriol is also required for ovulation (Halloran, 1989). 

Newborn infants present a special problem with respect to vitamin K. They have low plasma levels of prothrombin and the other vitamin K-dependent clotting factors (about 30% to 60% of the adult concentrations, depending on gestational age). To a great extent, this is the result of the relatively late development of liver glutamate carboxylase, but they are also short of vitamin K, as a result of the placental barrier that limits fetal uptake of the vitamin. This is probably a way of regulating the activity of Gas6 and other vitantin K-dependent proteins in development and differentiation (Section 5.3.4 Israels et al., 1997). 

In pregnant women, there is a progressive increase in the erythrocyte glutathione reductase activation coefficient (an index of functional riboflavin nutritional status Section 7.5.2), which resolves on parturition despite the daily secretion of 200 to 400 /rg (0.5 to 1 /rmol) of riboflavin into milk. This suggests that the estrogen-induced riboflavin binding protein can sequester the vitamin for fetal uptake at the expense of causing functional deficiency in the mother. 

Placental transfer occurs and, though there may be some fetal uptake, Apgar scores did not appear to be affected (10,11). 

Khayat A, Dencker L. 1982. Fetal uptake and distribution of metallic mercury vapor in the mouse -influence of ethanol and aminotriazole. Int J Biol Res Pregnancy 3 38-46. 

The answer is c. (Murray, pp 627-661. Scriver, pp 3897—3964. Sack, pp 121-138. Wilson, pp 287-320.) Hemorrhagic disease of the newborn is caused by poor transfer of maternal vitamin K through the placenta and by lack of intestinal bacteria in the infant for synthesis of vitamin K. The intestine is sterile at birth and becomes colonized over the first few weeks. Because of these factors, vitamin K is routinely administered to newborns. Deficiencies of the fat-soluble vitamins A, E, D, and K can occur with intestinal malabsorption, but avid fetal uptake during pregnancy usually prevents infantile symptoms. Hypervltaminosis A can cause liver toxicity but not bleeding, and deficiencies of E (neonatal anemia) or C (extremely rare in neonates) have other symptoms besides bleeding. 

Flavones. In rats given doses of flavone (Ipriflavone, 7-isopropyl-isoflavone, or Morin, 2, 2,4, 5,7-pentahydroxy-flavone) for 3 weeks prior to acute oral exposure to radiostrontium, the whole body retention of radiostrontium was reduced by 50 and 30%, respectively after 1 month (Gachalyi et al. 1988). Similar experiments on pregnant rats demonstrated that both flavones reduced fetal uptake of radiostrontium administered to dams on gestational days 17/18 and 19/20. No studies were located that demonstrated the usefulness of flavones for emergency situations, rather than as pretreatments. 

Hartsook EW, Hershberger TV. 1973. Strontium-calcium discrimination during placental transfer and fetal uptake in rats Effect of gestation duration. Proc Soc Exp Biol Med 143(2) 343-349. 

Tc-HSA was labeled by the method of Stern et al. (1965). Preparations showed high in vitro stability and contained virtually no free radionuclide when injected. Yet, no explanation has been given for the rapid liberation of technetium-99m from albumin after injection reflected in the rapid initial plasma clearance, the excretion pattern, and the evidence of fetal uptake of pertechnetate. 

Welsch, F. (1982). Placental transfer and fetal uptake of drugs. J. Vet. Pharmacol Ther. 5,91-104,... 

---