[Metabolism of vitamins B1 and PP and their use in oncological practice]. / Obmen vitaminov B1 i PP i ikh primenenie v onkologicheskoi praktike.

Blood of patients with gastric tumor was studied after their admission to the hospital and after the chemotherapeutic course. Formation of the tumor was accompanied by development of hypovitaminoses B1 and PP. The vitamin deficiency was more distinct after treatment of the patients with cyclophosphan: content of thiamine diphosphate (TDP) was decreased by 40%; NAD+NADP, by 30% and NADH+NADPH, by 20%. In mice with Ehrlich ascites carcinoma, activity of transketolase in erythrocytes was decreased by 48%, content of TDP, by 61% and that of NADPH, by 27%. The administration of cyclophosphan increased further thiamine deficiency in the tumor-bearing mice. Simultaneous administration of thiamine and cyclophosphan abolished the cytostatic toxic effect but did not affect their antitumoral properties. Under these conditions treatment with vitamins B1 and PP complex was undesirable due to malignization. The vitamins B1 and PP did not stimulate the tumor growth, partially restored impaired metabolism of the vitamins and may be included separately into combined multidrug oncotherapeutics.

[Biochemical changes in the rat immunocompetent organs during oxythiamine involution of the thymus]. / Biokhimicheskie izmeneniia v immunokompetentnykh organakh krys pri oksitiaminovoi involiutsii timusa.

Oxythiamine injections to rats (400 mg/kg of body mass, subcutaneously, 2 injections with 48 hrs interval) caused 70% involution of thymus within 72 hrs after the first injection. The transketolase activity was inhibited by 70%, that of glucose-6-phosphate dehydrogenase by 15%, while the aldopentose level was decreased by 56% in the thymus. Inhibition of DNA and RNA synthesis was directly dependent on the dose and duration of the oxythiamine effect on the gland. Reduction of transketolase activity was accompanied by an adaptive; increase in glucose-6-phosphate dehydrogenase activity as well as by a decrease in levels of nicotinamide coenzymes (NAD, NADP) in spleen.

[Niacin deficiency and correlation between oxidative reactions of the pentose phosphate pathway of carbohydrate metabolism and transketolase activity]. / Niatsinovaia nedostatochnost' i sootnoshenie okislitel'nykh reaktsii pentozofosfatnogo puti obmena uglevodov s aktivnost'iu transketolazy.

Rat were kept on the niacine-deficient diet with addition of excess L-leucine. This led to an appreciable reduction of the level of all the forms of nicotinamide coenzymes in the liver, heart, brain and blood, as well as to the loss of niacine function (as coenzyme) in dehydrogenase reactions in the test tissues. The increase in the glucose-6-phosphate level in the heart dependent on changes in the activity of glucose-6-phosphate dehydrogenase. The keeping on the diet devoid of niacine was followed by activation of blood transketolase and by transition of the biosynthesis of pentosophosphates from the oxidative to the non-oxidative branch of the pentosophosphate pathway. Administration of 3-acetylpyridine to both intact and avitaminotic rats revealed vitamin action of the preparation on the level of nicotinamide coenzymes and the activity of NADP-dependent dehydrogenase and showed that 3-acetylpyridine is not fit as antivitamin for use with a purpose of aggravating niacine deficiency in rats under the experimental conditions described.

[Glucose-6-phosphate transformation in the tissues of animals which have received high doses of hydroxythiamine or thiamine]. / Prevrashcheniia gliukozo-6-fosfata v tkaniakh zhivotnykh poluchaiushchikh vysokie dozy oksitiamina ili tiamina.

Administration of hydroxythiamin or thiamin into rats at a dose 400 mg/kg body weight caused a single-directed (unspecific, nonenzymatic) effect on the activity of glucose-6-phosphate and 6-phosphogluconate dehydrogenases within short periods (3-12 hrs). Within 24 and 72 hrs the effects of vitamin and antivitamin acquired the opposite (specific) direction towards the activity of glucose-6-phosphate dehydrogenase in liver tissues. Content of glucose-6-phosphate was altered depending on time of hydroxythiamin effect. Reverse correlation between the activity of glucose-6-phosphate dehydrogenase and content of the substrate was observed in heart muscle either after administration of hydroxythiamin or thiamin; the phenomenon suggest that dehydrogenase reactions affect considerably the regulation of glucose-6-phosphate content in the tissue.

[Effects of hydroxythiamine and citrate on several reactions of the pentose phosphate cycle and glycolysis]. / Osobennosti vliianiia oksitiamina i tsitrata na nekotorye reaktsii pentozofosfatnogo tsikla i glikoliza.

Hydroxythiamin was shown to inhibite distinctly phosphofructokinase and phosphohexoisomerase besides a direct antivitaminous effect on transketolase. In this case the regulatory action is likely to be carried out by erythrose-4-phosphate, accumulating in liver tissue. Citrate (administered separately and together with hydroxythiamin) is assumed to influence indirectly the transketolase activity affecting the total regulation of carbohydrate metabolism.