Nature of inhibition of rat testicular alkaline phosphatase by isatin

Summary Isatin has been found to inhibit rat testicular alkaline phosphatase (EC 3.1.3.1). That the inhibition is non-competitive as well as non-allosteric is evident from a) the hyperbolic curve relating inhibition as a function of inhibitor concentration; b) the small change in enthalpy, free energy and entropy; c) the number of isatin molecules associating with 1 molecule of the enzyme (n=1.29); and, d) the decrease in the values of both K_m and V_max in the presence of isatin.     

Thyroid activity in response to some gonadal steroids in methallibure-treated Heteropneustes fossilis (Bloch).

Methallibure treatment is as effective as hypophysectomy in reducing thyroid activity in H. fossilis. Sex steroids (TP and EB) administration restored thyroid activity in methallibure-treated females to normal level, but failed to elicit any response in males. This drug seems to block TSH secretion and thyroid hormone synthesis in H. fossilis.     

The biliary excretion of [3H] lysergic acid diethylamide in Wistar and gunn rats

Summary The biliary excretion of [³H] LSD was studied in Wistar and homozygous Gunn rats. In Wistar rats approximately 46% of the given dose was recovered from bile in 2.5 h whilst in the homozygous Gunn rat 26% was recovered in the same time period. In both strains the main metabolites were glucuronides.     

Contraction of frog stomach muscle and heart in non-ionic solutions

Zusammenfassung Herz und Magenmuskulatur des Frosches verlieren in halb-isotoner Rohrzuckerlösung innert 1 h alles Natrium. Trotzdem bleibt die spontane Kontraktilität erhalten. Natrium ist also für die Erregbarkeit dieser Muskeln nicht Voraussetzung.     

Isolation and structure of the strong cell growth and tubulin inhibitor combretastatin A-4

The African tree Combretum caffrum (Combretacae) has been found to contain a powerful inhibitor of tubulin polymerization (IC50 2-3 microM), the growth of murine lymphocytic leukemia (L 1210 and P 388 with ED50 approximately 0.003 microM and human colon cancer cell lines [(e.g. LoVo (ED50 = 0.005 microgram/ml), HT 29 (ED50 0.02 microgram/ml, Colo 205 (ED50 = 0.07 microgram/ml), DLD-1 (ED50 = 0.005 microgram/ml) and HCT-15 (ED50 = 0.0009 microgram/ml] designated combretastatin A-4 (1c). The structure assigned by spectral techniques was confirmed by synthesis.     

Gamma-glutamyl-transpeptidase in lymphatic tissues of Mastomys natalensis during an infection with Acanthocheilonema viteae

During Acanthocheilonema viteae infection, the specific activity of gamma-glutamyltranspeptidase (gamma-GT) increased in peritoneal exudate cells and bone marrow and decreased in lymph nodes of Mastomys natalensis throughout the course of infection. However, though there was an increase in specific activity of gamma-GT in thymus and spleen during the prepatent phase of A. viteae infection, the level either returned to normal or decreased during the latent phase of infection. A close correlation was observed between the host's immune status during A. viteae infection and the level of gamma-GT in lymphoid tissues.