Labeling of steroids with tritium

Conditions have been elaborated for the tritium labeling of some steroids to a molar activity of the order of 1 TBk/mol by heterogeneous catalytic isotopic exchange. For steroids without a keto group, isotopic exchange with gaseous tritium is most effective in neutral solvents, whereas for steroids with a keto group an alkaline medium is preferable. At certain pH values it was possible to void hydrogenation of the double bonds in the compounds.     

Physicochmemical characteristics of the new antineoplastic antibiotic, nocamycin]

Nocamycin is produced by Nocardiopsis syringae. It is recovered from the culture fluid by extraction with chloroform. The molecular weight of the crystalline antibiotic is 503, its melting point is 147--149 degrees, [alpha]20 degrees D = --50 degrees (c. 0.21, chloroform), lambdamax235 and 348 nm(E1%sm= = 150 and 420), the summation formula is C26 H33NO9, the biological activity is 100000 Units/mg with respect to Bacillus mycoides. Nocamycin forms salts with alkalies soluble in water. On hydrolysis with an alkali it forms carbonic acid having no ester bond (IP spectrum) and methoxylic group present in the antibiotic molecule. Nocamycin is a new natural substance.     

The Tongue Structure in Scaly-Tailed Squirrels (Rodentia,Anomaluridae)

Biology Bulletin - Five of the seven modern species of the family Anomaluridae have been studied. Significant intergeneric differences in the structure of the tongue between Anomalurus and Idiurus...     

Influence of light on membrane potential of Neurospora crassa cells

In experiments with left atrial and right ventricular tissues fast sodium current (INa) was decreased by substituting sucrose for sodium in Tyrode's solution and with antiarrhythmic drugs--INa blockers (lidocaine, diphenylhydantoine and ethmozine). It was shown that INa decrease results in the growth of refractoriness (R) of the cardiac tissues. The hypothesis is advanced that the R growth caused by INa decrease is one of the mechanisms of selective sensitiveness of ischemic heart tissues to antiarrhythmic drugs--INa blockers.     

Changes in the lymphoid cells of DNA and purine nucleotide synthesis and sensitivity to glucocorticoids associated with impairment of differentiation and immune function during tumor growth in mice. Thymocytes

Some biochemical mechanisms underlying the impairments of cellular immunity were studied in C3Ha mice in the course of growth of transplantable and induced (ortoaminoazotoluol) solid hepatomas. During intensive hepatoma growth, the adenosine deaminase activity in host thymocytes was shown to be drastically (6 times) reduced, resulting in the elevation of dATP and dGTP concentrations (6- and 7-fold, respectively), the potential inhibitors of ribonucleoside diphosphate reductase. Consequently, the rate of DNA synthesis was reduced as can be evidenced by the decrease of (a) thymidine kinase activity, (b) 14C-thymidine incorporation into DNA, and (c) dTTP and dCTP pools. By the terminal period of hepatoma growth (both transplantable and induced one), the serum corticosterone content increased 3- and 8-fold, respectively. At the same time, specific binding of [3H]triamsinolone acetonide by thymocytes was augmented and the activity of terminal deoxynucleotidyl transferase increased the latter alterations, which can be regarded as a reflection (including other parameters mentioned) of the arrest of T-lymphocyte differentiation at the level of immature cortex thymocytes.