Prolactin binding to 7,12-dimethylbenz(a)anthracene-induced mammary tumors and liver in diabetic rats.

Growth rates of 7,12-dimethylbenz(a)anthracene-induced mammary tumors and the specific 125I-labeled prolactin binding to membrane fractions prepared from livers and tumors were studied in rats made diabetic by streptozotocin injection. Growth was inhibited in a majority of tumors and prolactin binding was reduced in both tumors and livers from diabetic animals. Prolactin binding to individual tumors varied over a wide range in both intact and diabetic animals. Scatchard analysis of binding data revealed that the apparent affinity of prolactin binding to liver and tumor membranes was similar (Ka approximately 3.0 X 10(9) M-1) and was not affected by diabetes. We suggest that the reduction in prolactin binding to tumors may render these tissues less responsive to prolactin and thereby explain, at least in part, the observed inhibition of tumor growth in diabetic rats. However, some tumors in diabetic animals regressed despite relatively high levels of prolactin binding activity. Therefore, additional factors most certainly play important roles in the mechanism(s) by which the growth of 7,12-dimethylbenz(a)anthracene-induced tumors is impaired in the diabetic rat.     

Value of Schwangerschaftsprotein 1 (SP1) and pregnancy-associated plasma protein-A (PAPP-A) in the clinical management of threatened abortion

Summary. Pregnancy-associated plasma protein-A (PAPP-A) and Schwangerschaftsprotein 1 (SP₁) levels were measured in single serum samples from 60 patients admitted with vaginal bleeding in the first 14 weeks of pregnancy. When based on ultrasound diagnoses the prediction of non-viability (the predictive value) was 97% for SP₁ and 84% for PAPP-A. Whereas the prediction of viability (above –2SD of the normal range) with SP₁ was 88% the value with PAPP-A was only 57%; the poorer result obtained with PAPP-A probably reflects its longer half-life. Pregnancy outcome is not related to the duration of bleeding.