Cytotoxic effect of methionine-gamma-lyase on neoplastic cells in culture

The influence of methionine-gamma-lyase from Pseudomonas putida on DNA synthesis by CaOv and L-8 cell lines has been studied. The agent has been demonstrated to inhibit the incorporation of 3H-thymidine into L-8 cell line and to have no effect on CaOv cells.     

Biotransformation of 1-beta-D-ribofuranosyl-4-methylthiopyrazolo(3,4-d)pyrimidine and its 5'-monophosphate

1-beta-D-Ribofuranosyl-4-methylthiopyrazolo(3,4-d)pyrimidine (I) has been converted into its 5'-monophosphate (III) by reacting with POCl3 in trialkyl phosphates or by phosphorylating 2',3'-O-ethoxymethylidene derivative of riboside (I) using 2-cyanoethyl phosphate in the presence of DCC and subsequent removal of blocking groups. Condensation of nucleotide (III) imidazolide with pyrophosphoric acid afforded corresponding 5'-triphosphate. Pools of natural NTPs and riboside (I) phosphates were monitored by HPLC after administering riboside (I), phosphate (III), or 4-methylthiopyrazolo(3,4-d)pyrimidine (II) into mice with leukemia L1210 or after incubating CaOv culture cells with these compounds. Treatment with riboside (I) or nucleotide (III) possessing antileukemic and cytotoxic activites led to much higher level of monophosphate (III), than treatment with biologically inactive base (II). ATP and GTP levels in CaOv cells incubated with (I) or (III) decreased by 60-70%, whereas (II) did not affect NTP pool. Bioactivation of nucleoside (I) into monophosphate (III) proceeds via direct phosphorylation by adenosine kinase. No tranformation of (II) into (I) or (III) occurs under these conditions.     

The reactivity of the mesenteric metarterioles of the rabbit in early postnatal ontogeny

Television microscopic studies have been made of the reaction of mesenterial metarterioles to noradrenalin in newborn, 10- and 30-day rabbits. The results obtained show the existence of postnatal changes in the reactivity of arterioles with a diameter 20-25 mu. Within the period investigated, noradrenalin sensitivity of metarterioles decreases whereas their contractile activity increases. It is suggested that formation of functional properties of metarterioles is not accomplished to the birth of rabbits.