Neonatal screening for hypothyroïdism by simultaneous determination of T4 and TSH on filter paper

Abstract

Human growth hormone bincing to liver membranes of rats with renal insufficiency.Binding sites for human growth hcrmone (hGH) were studied in liver membranes of female rats with chronic renal insufficiency (CRI) associated to marked growth retardation. One month after a subtotal nephrectomy the animals kith a plasma creatinine level > 3 times that of controls were studied ; their mean statural gain wag 56 % that of controls. The specific binding of I251-hG~ to microsomal membranes of rats with CRI was low (62 % that of controls). The number of binding sites rather than the affinity of the binding was affected ; both the lactogenic and the somatotropic sites were decreased as judged on the binding of 1 2 5~-o~~~ and 1 2 5~-b~~. The binding sites of the plasma membranes as well as those of Golgi fractions were reduced. In plasma membranes of rats with CRI the specific binding of glucagon was low and the specific binding of insulin was elevated ; these modifications were associated with a high plasma glucagon level and a decreasei insulinemia in rats with CRI. But no modification of the plasma GH and PRL was found ; the hormone level does not appear to regulate the GH binding sites in this system.The link between the growth defec: and the decreased number of GH binding sites in the liver meml~ranes of rats with CRI remains to be established. Testosterone (T) and dihydrotestoaterone (DHT) were found to bind to a specific protein in fornskin fibroblasts of a male pseudohermaphrodite with 5d(-reductase deficiency. While maximum number of binding sites (B max) were similar for both androgens, the apparent dissociation constant (Kd) of the androgen receptor for T was greater than for DHT. In competition studies of 3~-T bound to the receptor with unlabeled T or DHT, the inhibitor constant (K;) for T was two to three fold greater than the Kj for DHT. Also, the dissociation rate constant (kd) for 3~-T bound to the receptor was greater than for 3~-~~~ (t 112 for T = 10 h and t 112 for DHT = 74.5 h).These results suggest that T may play a role in the sexual differentiation of patients with 51-reductase deficiency. Their incomplete masculinization would be explained by the lower affinity and faster turnover rate of the T-receptor complex relative to the DHT-receptor complex.A. ROSCRER*, U. WIESMANN*, K. ZUPPINGER, Pediatric 31 Clinic, University of Berr e, 3010 Berne, Switzerland.Reduced plating efficient) of Turner's syndromefibroblasts. Evidence for a peripheral rezistance to growth factors? Short stature in Turner's syndrome (TS) has been postulated to be caused by reduced target organ re:ponsiveness to growth factors, although the experimental proof is lacking. Therefore growth properties and cell kinetics cf cultured skin fibroblasts from 5 patients with TS (45,XO) were characterized and compared to those of 5 normal fibroblast cultures using 10% fetal calf serum in Eagle's MEM medium as a source of growth factors. Replicate cultures were plated at 2000 cells/cm2 and grown for 8 days without medium change. Although the f...