RESUMO
Somatomedin activity was determined by the simultaneous incorporation of 35S-sulfate and 3H-methyl thymidine into costal cartilage from hypophysectomized rats in cord sera from term and preterm infants and infants with intrauterine growth retardation. Mean Sm activity by sulfate incorporation was 0.49 +/- 0.04, 0.35 +/- 0.05, and 0.09 +/- 0.03 units/ml (+/- SE) in the term, preterm, and IGR cord sera, respectively. The levels for each group were significantly different from each of the other groups. There was no significant difference between the mean Sm activity by thymidine incorporation in cord sera from term (0.92 +/- 0.09 units/ml) and preterm (0.87 +/- 0.08 units/ml) infants. These levels were significantly higher, however, than the Sm activity by sulfate incorporation for the respective groups, P less than 0.001 for both groups. The mean Sm activity by thymidine incorporation in cord sera for IGR infants was 0.36 +/- 0.13 units/ml, and significantly lower than the levels in cord sera of term and preterm infants (P less than 0.01). Inhibition of Sm activity by mixing cord serum and pooled adult serum was found in one of the two cord specimens tested from IGR infants. The low levels of Sm activity in cord sera from IGR infants may reflect altered intrauterine nutrition. The discrepancy in the thymidine and sulfate incorporation by the costal cartilage bioassay for term and preterm cord sera might result from Sm-like factors in human fetal serum with greater mitogenic or thymidine transport activity compared to the activity for proteoglycan synthesis in cartilage.
Assuntos
Sangue Fetal/análise , Retardo do Crescimento Fetal/sangue , Somatomedinas/sangue , Anencefalia/sangue , Feminino , Humanos , Recém-Nascido , Recém-Nascido Prematuro , GravidezRESUMO
Serum prolactin (PRL) was measured by radioimmunoassay in pregnant women at term and in newborns. In 38 newborns of gestational age 39--40 weeks, concentration of PRL in umbilical venous blood was 280.8 +/- 11.2 ng/ml; in maternal venous blood, concentration of PRL was 347.0 +/- 20.1 ng/ml. In the newborn it was found a significant difference in PRL values between both sexes (p less than 0.05), being higher in males than in females (290.0 +/- 14.6 vs. 260.0 +/- 17.1 ng/ml). In three anencephalic infants, PRL ranged from 92.6 to 369.0 ng/ml; 400 mug of thyrotropin-releasing hormone (TRH) administered as bolus injection evoked a rise in PRL in two out of the three, while synthetic luteinizing hormone releasing hormone (LH-RH) elicited no response of FSH secretion. These observations in the fetus and anencephalic infants confirm that the fetus produces high levels of PRL and that this function is independent of any hypothalamic control. The high levels of gestational estrogens seem to be the direct stimulus on the lactotropes to induce synthesis and secretion of PRL. The role of PRL during gestation has not been elucidated.