Short-term stimulatory effect of Sertoli cell conditioned medium on Leydig cell steroidogenesis is not mediated by inhibin

Addition of concentrated rat Sertoli cell conditioned medium (rSCCM) to isolated Leydig cells from immature rats stimulated steroid production more than 13-fold within 4 h. LH-stimulated steroidogenesis was not enhanced by addition of rSCCM. The biological activity of the concentrated rSCCM was higher after incubation of Sertoli cells with FSH, whereas FSH alone did not stimulate steroid production. This effect of rSCCM was not due to inhibin, since highly purified 32 kDa rat inhibin, in doses equivalent to those present in rSCCM, had no effect on steroidogenesis during the 4 h incubation period. Furthermore, inhibin could be separated from the Leydig cell stimulating factor by anion-exchange chromatography. These results indicate a short-term paracrine control of Leydig cell steroidogenesis by Sertoli cell derived factors, which differ from inhibin.     

Rescue of DeltaF508-CFTR trafficking and gating in human cystic fibrosis airway primary cultures by small molecules

Cystic fibrosis (CF) is a fatal genetic disease caused by mutations in cftr, a gene encoding a PKA-regulated Cl(-) channel. The most common mutation results in a deletion of phenylalanine at position 508 (DeltaF508-CFTR) that impairs protein folding, trafficking, and channel gating in epithelial cells. In the airway, these defects alter salt and fluid transport, leading to chronic infection, inflammation, and loss of lung function. There are no drugs that specifically target mutant CFTR, and optimal treatment of CF may require repair of both the folding and gating defects. Here, we describe two classes of novel, potent small molecules identified from screening compound libraries that restore the function of DeltaF508-CFTR in both recombinant cells and cultures of human bronchial epithelia isolated from CF patients. The first class partially corrects the trafficking defect by facilitating exit from the endoplasmic reticulum and restores DeltaF508-CFTR-mediated Cl(-) transport to more than 10% of that observed in non-CF human bronchial epithelial cultures, a level expected to result in a clinical benefit in CF patients. The second class of compounds potentiates cAMP-mediated gating of DeltaF508-CFTR and achieves single-channel activity similar to wild-type CFTR. The CFTR-activating effects of the two mechanisms are additive and support the rationale of a drug discovery strategy based on rescue of the basic genetic defect responsible for CF.     

Ultrastructure of the intra-erythrocytic stage of Theileria species from cattle and waterbuck

A transmission electron microscopic study of the intra-erythrocytic stages of a pathogenic Theileria parva from cattle and a previously uncharacterized Theileria sp. from waterbuck (Kobus defassa) in Kenya revealed several novel ultrastructural features, associated with feeding and multiplication, in these parasites. In trophozoites a connecting channel was observed between the parasite's cytostome and its intracytoplasmic food vacuole. In some cases the limiting membrane of the food vacuole was seen to be continuous with a close-meshed network of membrane-bounded, anastomosing tubules. This labyrinthine structure, which has not been described previously, may function as a digestive organelle in theilerial trophozoites. Electron micrographs also revealed the mode of intra-erythrocytic multiplication of these parasites in vivo. Prior to division, electron-dense cisternae and rhoptries appeared beneath the parasite's plasmalemmal membrane, marking the sites of merozoite formation. From a single parasite, a maximum of four merozoites were formed by schizogonous division and subsequently separated from a residual body by constriction at the base of each merozoite. In addition, observations on two double-membraned organelles seen in trophozoites and the intra-erythrocytic crystalline structures associated with Theileria sp. in waterbuck are reported.     

Inhibin immunoreactivity in gonadal and non-gonadal tumors

Inhibin immunoreactivity was estimated in a number of gonadal and non-gonadal tumors. Dog Sertoli cell tumors and human granulosa cell and Leydig cell tumors contained high concentrations of inhibin-like material. Levels, comparable with those in normal testes and ovaries were detected in human testicular non-seminomas and in ovarian cystadenomas, thecomas and adenofibromas. No activity was found in human testicular Sertoli/Leydig cell tumors and seminomas and in ovarian adenocarcinomas, teratomas and a dysgerminoma. Furthermore, human adrenal cortical tissue (tumor and hyperplastic adrenal) contained inhibin immunoreactivity. No activity was found in human tumors of the stomach, gut, liver, kidney, pancreas and mammary gland or in meningiomas. It is concluded that inhibin is not a good marker for specific gonadal tumors. Inhibin might have intratumor actions a growth or differentiation factor.     

Novel acylguanidine containing thrombin inhibitors with reduced basicity at the P1 moiety

Replacement of the noragmatine group in thrombin inhibitors with a ß-alanyl-guanidine group resulted in a nearly equipotent and more selective compound 8 despite the fact that the pK_a of this P₁ moiety is five orders of magnitude lower. Further modification resulted in a nonpeptide inhibitor with this ß-alanyl-guanidine group, compound 28. This is an active and selective thrombin inhibitor and in view of its nonpeptide/low basicity structure selected for further pharmacological studies.