[Functional activity of blood and liver cells under formaldehyde intoxication via inhalation].

The influence of formaldehyde (of 5 and 10 mg/m3) on the state of the antioxidant system the blood and liver of rats, the activity of pentose phosphate pathway enzymes, and weight of immune organs was investigated. Formaldehyde intoxication led to activation of lipid peroxidation processes in red blood cells and hepatocytes. In the liver cells these changes were accompanied by activation of the antioxidant and detoxification systems. Formaldehyde depleted thiamine diphosphate in the liver, and this effect was not dose-dependent. The number of blood cells remained unchanged. Formaldehyde at the concentration of 10 mg/m3 exerted the negative effect on the thymus. This effect may be related to stimulation of lipid peroxidation.

The effect of thiamine supplementation on tumour proliferation. A metabolic control analysis study.

Thiamine deficiency frequently occurs in patients with advanced cancer and therefore thiamine supplementation is used as nutritional support. Thiamine (vitamin B1) is metabolized to thiamine pyrophosphate, the cofactor of transketolase, which is involved in ribose synthesis, necessary for cell replication. Thus, it is important to determine whether the benefits of thiamine supplementation outweigh the risks of tumor proliferation. Using oxythiamine (an irreversible inhibitor of transketolase) and metabolic control analysis (MCA) methods, we measured an in vivo tumour growth control coefficient of 0.9 for the thiamine-transketolase complex in mice with Ehrlich's ascites tumour. Thus, transketolase enzyme and thiamine clearly determine cell proliferation in the Ehrlich's ascites tumour model. This high control coefficient allows us to predict that in advanced tumours, which are commonly thiamine deficient, supplementation of thiamine could significantly increase tumour growth through transketolase activation. The effect of thiamine supplementation on tumour proliferation was demonstrated by in vivo experiments in mice with the ascites tumour. Thiamine supplementation in doses between 12.5 and 250 times the recommended dietary allowance (RDA) for mice were administered starting on day four of tumour inoculation. We observed a high stimulatory effect on tumour growth of 164% compared to controls at a thiamine dose of 25 times the RDA. This growth stimulatory effect was predicted on the basis of correction of the pre-existing level of thiamine deficiency (42%), as assayed by the cofactor/enzyme ratio. Interestingly, at very high overdoses of thiamine, approximately 2500 times the RDA, thiamine supplementation had the opposite effect and caused 10% inhibition of tumour growth. This effect was heightened, resulting in a 36% decrease, when thiamine supplementation was administered from the 7th day prior to tumour inoculation. Our results show that thiamine supplementation sufficient to correct existing thiamine deficiency stimulates tumour proliferation as predicted by MCA. The tumour inhibitory effect at high doses of thiamine is unexplained and merits further study.

Pantothenol protects rats against some deleterious effects of gamma radiation.

Rats were exposed to gamma radiation from a 60Co source, receiving 0.25 Gy at weekly intervals. During 2 d before each irradiation, the animals received daily intragastric doses of 26 mg pantothenol or 15 mg beta-carotene per kg body weight. One hour after the third irradiation session, the animals were killed and their livers were analyzed. In animals not supplied with pantothenol, the irradiation resulted in a significant decrease of total liver lipids and a 50% decrease in phospholipids. Liver cholesterol was decreased by about 20%. Irradiation produced lipid peroxidation as expressed by doubling of the amounts of conjugated dienes and ketone dienes and of thiobarbituric acid reactive compounds. The amount of CoA in liver was decreased by 24% and that of reduced glutathione by 40%. The NAD+/NADH ratio was increased by 60% and the activity of NADP-dependent malate dehydrogenase (decarboxylating) was decreased by 26%. The amount of pantothenic acid and its derivatives (expressed as pantolactone-generating compounds) in blood decreased by about 80%. In rats to which pantothenol was administered, the content of pantothenic acid in blood was tripled compared to nonirradiated (control) rats, and all the biochemical parameters measured in liver were the same as in nonirradiated animals.

[Metabolism of vitamin B1 and its di- and triphosphate esters in experimental allergic encephalomyelitis]. / Metabolizm vitamina B1 i ego di- i trifosfornogo efirov pri éksperimental'nom allergicheskom éntsefalomielite.

Biological significance of thiamin in development of experimental allergic encephalomyelitis has been elucidated. It has been shown that at the late preclinical stage of the disease thiamine metabolism is predominantly directed towards the maintaining of cellular metabolic homeostasis, whereas at the stage of clinical symptoms the anabolic process gives way to catabolic decomposition. Among tested thiamine phosphates the triphosphate ester is the most informative parameter in demyelinizing processes. Thiamine injections to immunized animals accelerate the vitamin phosphorylation depleting the reducing and energy potentials of the cell. Such thiamine antagonist as oxythiamine inhibits phosphatase reactions.

[The effect of oxythiamine on tumor growth and certain biochemical and genetic characteristics of normal and tumor cells]. / Vliianie oksitiamina na opukholevyi rost i nekotorye biokhimicheskie i geneticheskie kharakteristikie normal'nykh i opukholevykh kletok.

The effect of oxythiamine (400 mg/kg) on chromosomal structure of Ehrlich ascites carcinoma cells (EAC, hyperdiploid strain) and bone marrow cells was studied in intact AF mice. The influence of the antivitamin on the rate of tumor growth was investigated in tumor-bearing mice. Oxythiamine decreased transketolase activity in hepatocytes and tumoral cells and markedly inhibited tumor growth. Amount of chromosomes was unaltered both in tumor cells and in bone marrow cells, which could be manifested as increased content of cells with impairment of chromosomal set calculated per a cell. However, the oxythiamine-induced impairment of chromosomal integrity was less distinct as compared with the effect of such mutagens as urethane and cyclophosphamide; hence, the antivitamin might be used in the courses of combined chemotherapy.

[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.

[Thiamine diphosphate pool and its biosynthesis in the liver in galactosamine hepatitis]. / Pul tiamindifosfata i ego biosintez v pecheni pri galaktozaminovom gepatite.

The hepatitis-like changes were induced in the liver of albino female rats weighing 120-150 g and fed on the appropriate vivarium diet by single parenteral administration of hydrochloride galactosamine in a dose of 0.9 or 1.8 mmol per 1 kg of body weight. The thiamine diphosphate level in the cytosol fraction of the liver decreased 24 h after the preparation administration, the same in blood but with the higher dose used. The activity of pyruvate dehydrogenase, a thiamine diphosphate dependent enzyme, decreased similarly. The cytosol transketolase activity lowered by 38-39%. The coenzyme biosynthesis disturbance due to a fall by 49-58% in the thiamine pyrophosphatase activity is considered to be responsible for hydrochloride galactosamine-induced decrease in the thiamine diphosphate pool. Specificity of the thiamine diphosphate pool disturbance and discoordination of thiamine diphosphate dependent enzymes in the liver are observed under administration of hydrochloride galactosamine.

[Interstitial thiamine redistribution during the development of vitamin B1 deficiency in mice]. / Mezhtkanevoe pereraspredelenie tiamina pri razvitii defitsita vitamina B1 u myshei.

Investigation of diphosphothiamine content in the mouse tissues, associated with transketolase activity in the dynamic dependence on the body provision with vitamin B1, has proved the organ-specificity of deposition and elimination of diphosphothiamine under conditions of developing thiamine deficiency. The experimental data have evidenced that vitamin B1 exclusion from the food ration results in the diphosphothiamine redistribution between the tissues and in the provision with coenzymes of one tissue at the expense of the other.

[Effect of thiamine and its antimetabolite oxythiamine on the proliferative activity of carcinosarcoma Walker 256 cells]. / Vliianie tiamina i ego antimetabolita oksitiamina na proliferatsiiu kletok kartsinosarkomy Uoker 256.

The microscopic studies of tumours from rats injected with thiamine at a dose of 20 mg/kg for 5 days have shown that sites of hemorrhages and necrosis are considerably more extensive than in tumours of control animals. Injections of the same doses of oxythiamine increase the rate of pathologic mitoses in tumour cells and decrease the tumour weight by 45%, limit the synthesis of thiamine diphosphate and inhibit the transketolase activity in tissues.

[Level of thiamine diphosphate in the liver of tumor-bearing animals kept on a diet including an excessive amount of vitamin B 1]. / Uroven' tiamindifosfata v pecheni zhivotnykh-opukholenositelei, soderzhavshikhsia na ratsione s izbytochnym kolichestvom vitamina B 1.

In mice bearing solid Ehrlich's carcinoma, food consumption did not differ from that in intact animals throughout the whole experiment. In mice with Ehrlich's ascites carcinoma and in rats bearing Walker's carcinosarcoma 256, the daily feed consumption decreased 2-fold by the terminal period of tumor development. In rats, the amount of vitamin B1, calculated per unit of the feed consumed, exceeded the daily requirements of vitamin B1. The content of thiamine diphosphate in the liver of tumor-bearing animals was 35% as reduced whatever the method of inoculation and site of tumor development (under the skin or inside the abdominal cavity). In rats with Walker's carcinosarcoma 256, transketolase activity was 17% as lowered (P less than 0.01). In mice with Ehrlich's carcinoma, the activity of the enzyme was 21% as decreased (P less than 0.01; an ascitic variety) or 17% as decreased (P less than 0.01; subcutaneously inoculated tumor).

[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.

[Adaptive processes occurring during the development of thiamine deficiency]. / Adaptatsionnye protsessy protekaiushchie pri razvitii tiaminovogo defitsita.

In the presence of the total of the level of vitamin B1 derivatives, the liver shows an uniform decrease in the content of thiamine diphosphate (TDP) with phase changes in the activities of thiamine phosphokinase and thiamine pyrophosphatase. The activity of transketolase and the blood ratio of cholo- and apoform enzyme seen over time are liable to phase oscillations which are likely to mirror the involvement of the enzyme in TDP deposition and transport. The data obtained are regarded as evidence for adaptive shifts in the metabolism of thiamine proper, aimed at partial compensation for its deficiency by redistribution of the vitamin among different tissue of the body.

Turnover of [14C]thiamin and activities of thiamin pyrophosphate-dependent enzymes in tissues of mice with Ehrlich ascites carcinoma.

Turnover of [14C]thiamin was studied in mice with Ehrlich ascites carcinoma fed a thiamin-deficient diet and injected with 5 or 2 micrograms/mouse of the labeled vitamin. The process of conversion of [14C]thiamin to thiamin pyrophosphate (TPP) was monitored by measuring the activities of transketolase, pyruvate dehydrogenase, and oxoglutarate dehydrogenase. The amount of coenzyme-unsaturated apotransketolase was assessed by measuring the TPP effect--determining transketolase activity with and without the addition of TPP in vitro. Tumor growth was accompanied by thiamin deficiency, manifested in an increase in [14C]thiamin incorporation into the host tissues and the absence of saturation of the tissues with the labeled vitamin over 13 days. Increased values for the turnover coefficients, reduction of thiamin-dependent enzyme activities, elevation of the TPP effect, and a decrease in urinary excretion of the radioactive products also provided evidence for a disturbance in thiamin metabolism. The severity of the disturbance in thiamin metabolism during malignant tumor growth was directly related to the dose of the exogenous vitamin.

[Transketolase activity and thiamine diphosphate content in oncological patients]. / Aktivnost' transketolazy i uroven' tiamindifosfata u onkologicheskikh bol'nykh.

In blood of patients with cancer of stomach and mammary gland total thiamin content was measured by means of fluorimetric procedure, thiamindiphosphate (TDP)--by an enzymatic method, activity of transketolase was estimated in presence or in absence of TDP. Concentration of total thiamin in blood of healthy persons was 7.65 +/- 0.40 micrograms/100 ml; thiamindiphosphate--5.06 micrograms/100 ml activity of transketolase was 11.59 +/- 0.23 mmol/l. The "TDP" -effect was altered from 4% to 12%. In blood of oncological patients the concentration of total thiamin was 4.47 +/- 0.35 micrograms/100 ml and that of thiamindiphosphate 3.09 +/- 0.27 micrograms/100 ml, i.e. they were decreased by 40%. The transketolase activity was decreased by 20% (9.40 +/- 0.37 mmol/l); the "TDP" -effect was altered from 5% to 42%.

[Degradation of thiamine diphosphate in subcellular fractions of mouse liver in the dynamics of the development of alimentary B1-avitaminosis]. / Rasshcheplenie tiamindifosfata v subkletochnykh fraktsiiakh pecheni myshei v dinamike razvitiia éksperimental'nogo pishchevogo B1-avitaminoza.

Alterations in activity of specific and unspecific phosphatases, hydrolyzing thiamin diphosphate, were studied in microsomes, mitochondria and cytosol of mice liver cells in dynamics of alimentary B1-avitaminosis (4-21 days). Activity of the enzymes studied was increased as thiamin deficiency developed. Administration of thiamin into the avitaminous animals normalized the enzymatic activity, indicating the specific dependence of these alterations on the thiamin level in animal tissue.

Transketolase, pyruvate and oxoglutarate dehydrogenase activities and [14C]thiamin turnover in tissues of mice fed thiamin-deficient diet.

A study was made of turnover of [14C]thiamin (5 or 2 micrograms/mouse) in mice fed a thiamin-deficient diet. Simultaneously the activities of the thiamin-dependent enzymes (transketolase, pyruvate and oxoglutarate dehydrogenases) were measured as an index of efficiency of fulfilling the coenzyme function of the vitamin under conditions of different thiamin status. After [14C]thiamin injections of 5 micrograms/mouse, kidney, spleen, stomach and pancreas tissue stores turned over completely on day 9, whereas by day 13 this process had not yet been finished in liver, heart and brain. On administration of 2 micrograms [14C]thiamin/mouse, turnover of the tissue stores proceeded at a slower rate. The tissue transketolase activity decreased after the 2-microgram injections as compared to that in the mice administered 5-microgram injections. With 2 micrograms of [14C]thiamin, the pyruvate dehydrogenase activity lowered gradually in all the tissues studied, whereas the oxoglutarate dehydrogenase decreased in liver and kidneys. The pattern of the depression of the thiamin-dependent enzyme activities after the 2-microgram [14C]thiamin injections suggests a regularity in the vitamin redistribution in different organs and subcellular fractions.

[Transketolase activity and the TDP effect in tissues of animals with experimental tumors]. / Aktivnost' transketolazy i TDF-effekt v tkaniakh zhivotnykh s éksperimental'nymi opukholiami.

Activity of transketolase and the TDP-effect were studied in blood and liver subcellular fractions of mice with Erlich ascites carcinoma and of rats with sarcoma 45 which were maintained on a synthetic diet containing either all the vitamins or devoid of thiamine. As compared with other mice liver subcellular fractions the microsomal fraction proved to be the most sensitive to thiamine deficiency: inhibition of transketolase activity reached 75%. Decrease in TDP-effect found in microsomes might reflect the most distinct terminal steps of B1 avitaminosis. As a result of vitamin B1 deprivation of mice with Erlich ascites carcinoma activity of transketolase was decreased by 30% and the TDP-effect increased by 34% in the liver microsomal fraction; in the tumoral cells the enzymatic activity was decreased by 23% and the TDP-effect was increased by 10%. Thiamine-free ration of rats with sarcoma 45, at the initial steps of the tumor growth was responsible for the most distinct decrease in transketolase activity and an increase in the TDP-effect in blood.

[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.

[Vitamin B6 metabolism in mice with Ehrlich ascites tumor]. / Obmen vitamina B6 u myshei s astsitnoi opukhol'iu Erlikha.

Experiments on mice with Ehrlich's ascites carcinoma were made to explore absorption, intertissue distribution and excretion of 3H-pyridoxine upon enteral and parenteral administration of labeled vitamin in a dose of 0.5 microgram per mouse. The rate of 3H-pyridoxine penetration to the blood flow of the tumor-bearing animals was not different from that in the controls. This may be viewed as the absence of abnormalities in vitamin absorption in the gastrointestinal tract. As the tumorous process develops, there takes place a progressive binding of the labeled vitamin in the tissues: in the muscle, by 17%, in the liver, by 32%, in the brain, by 42%, and in the heart, by 54%. Excretion of radioactive metabolites with the urine decreases. In the tumorous cells, the concentration of the labeled vitamin by the 10th day of the tumor growth increases 1,5-fold as compared to that seen within the initial observation period. Additional administration of pyridoxine (100 microgram/mouse) for 8 days did not stimulate the tumor growth, while the injections of vitamin B6 in a dose of 1 mg/mouse suppressed the growth of Ehrlich's ascites carcinoma in mice by 17%.