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Transplacental mutagenesis of products formed in the stomach of golden hamsters given sodium nitrite and morpholine.

Hamster embryos were exposed in utero to the action of sodium nitrite (NaNO2) and morpholine (Mo) administered simultaneously by stomach tube to the mothers on the 11th or 12th day of pregnancy. Embryo cells were examined for chromosomal aberrations, micronuclear formation, morphological or malignant transformation and drug resistance mutations. For detection of induced mutations, the embryo cells were cultured in normal medium for 72 h and then transferred to medium containing 10 or 20 micrograms/ml of 8-azaguanine (8AG) or 1m7 ouabain (Oua). The number of 8AG-, Ouaresistant colonies was markedly increased after administration of NaNO2 and Mo. The embryonic fibroblasts also showed a markedly increased frequency of micronucleation and a slight increase in chromosome aberrations. This treatment also caused morphological or malignant transformation of fetal cells. After cultivation in vitro, cells from some transformed colonies produced tumors when inoculated into the cheek pouch of young golden hamsters. Orally administered N-nitroso-morpholine (N-Mo), as a positive control, had the same transplacental biological actions on embryonic fibroblasts. However, transplacentally Mo alone was ineffective. A single administration of 500 mg/kg NaNO2 had only slight biological effects. N-Mo was produced in the stomachs of animals treated simultaneously with NaNO2 and Mo. A small amount of a nitrosamine, N-nitrosodimethylamine (DMN), was detected in the stomach after a single dose of NaNO2.

Animals

Nitrosation in vitro and in vivo by sodium nitrite, and mutagenicity of nitrogenous pesticides.

37 nitrogenous pesticides, belonging to the chemical groups of amides, carbamates and ureas, were nitrosated with sodium nitrite in vitro. The nitrosated compounds were tested for mutagenic activity in the bacterial spot test with Salmonella typhimurium his G 46. Those pesticides reacting positively in this test after nitrosation were then fed to mice in combination with sodium nitrite in order to assess the formation and mutagenicity of these nitroso compounds in vivo. With the already known exception of ethylenethiourea (ETU), no pesticide produced enhanced numbers of micronuclei in mouse bone-marrow erythrocytes when fed together with nitrite. Dose-response experiments with intraperitoneal injection of N-nitroso-ETU revealed an apparent no-effect level of about 15--18 mg/kg. The findings are correlated with the pesticide residues actually present in the environment.

Animals

[Effect of nitroglycerin and sodium nitrite on myocardial mitochondrial respiration and oxidative phosphorylation normally and in coronarogenic ischemia].

The effect of nitroglycerin and sodium nitrite (2.10(-6), 2.10(-5) and 2.10(-4) g/ml) on respiration and oxidative phosphorylation of mitochondria of the normal and ischemized dog myocardium has been investigated in the presence of glutamate, succinate and alfaketoglutarate. The drugs inhibited ADP-activated oxygen consumption and ADP phosphorylation rate upon oxidation of succinic acid formed in mitochondria from exogenic glutamate, without changes in the phosphorylation coefficient and free oxidation rate (i. e. in the absence of ADP) in mitochondria of the healthy and ischemic heart. In the ischemic area one can also observe an inhibition of ADP-activated oxidation of endogenic succinate formed from exogenic glutamate.

Animals

[Effects of sodium nitrite on various vitamin concentrations in rat tissues].

For 6 months 2 groups of 10 male Wistar rats were fed on a chow ration, and to drink they were given either de-ionized water or a solution of sodium nitrite, 0.3 g per litre. At the end of the experiment thiamine, riboflavin, vitamin B6, niacin, biotin and pantothenic acid were estimated in various tissues (liver, heart, muscle, encephalon, kidneys, spleen, lungs and duodenum); nitrogen, phosphorus, retinol and ascorbic acid were estimated in the liver only. There was no difference between the groups in changes in bodyweight or fluid intake, nor in weight of different organs. But in the animals given sodium nitrite there was an increase in riboflavin, vitamin B6, niacin and pantothenic acid spleen concentrations, and a decrease in liver niacin and encephalon biotin contents.

Animals

Inhibitor of Clostridium perfringens formed by heating sodium nitrite in a chemically defined medium.

An inhibitor of Clostridium perfringens formed when low levels of nitrite were autoclaved with a defined chemical medium. A systematic study of the medium revealed that only amino acids and mineral salts were involved in the production of this inhibitor, which was proven to be a toxic compound formed from cysteine, ferrous sulfate, and sodium nitrite. The inhibitor was compared to several known compounds. S-nitrosocysteine inhibited the test organism, but would not form in the test system in amounts large enough to explain the observed inhibition. Roussin red salt was unstable in the test system and therefore was not the inhibitor. Roussin black salt, which was also inhibitory, could form in sufficient amounts to explain the inhibition. A complex of cysteine, iron, and nitric oxide was detected in the autoclaved solution of cysteine, ferrous sulfate, and sodium nitrite; this cysteine complex did not appear to be inhibitory, however, at levels which could form in the autoclaved medium. The observed inhibition may have been due to the combined effects of sublethal concentrations of each compound.

Anti-Bacterial Agents

Transplacental effects of ethylnitrosourea precursors ethylurea and sodium nitrite in hamsters.

Four simultaneous dosages of the ethylnitrosourea precursors, ethylurea and sodium nitrite, were administered intragastrically to pregnant hamsters at 100 mg/kg and 50 mg/kg respectively, from the 12-15th days of pregnancy. The treatment induced multiple neurogenic tumors of the peripheral nervous system in the offspring. Female progeny developed a greater incidence and multiplicity of peripheral nervous system tumors with significantly shorter latencies than males, thus establishing evidence that the tumors were age and sex dependent. The tumors presented varied morphological patterns and upon transplantation, grew regularly, exhibiting their malignant nature. The possible influence of estrogenic hormones on the development and growth of peripheral nervous system tumors and comparative aspects of the relationship between prenatal and postnatal carcinogenesis with regard to the ensuing tumor spectra as a consequence of exposure to the same chemical agent, are discussed.

Animals

Sodium nitrite and sorbic acid effects on Clostridium botulinum spore germination and total microbial growth in chicken frankfurter emulsions during temperature abuse.

Samples of (i) a control or of (ii) sodium nitrite-containing or (iii) sorbic acid-containing, mechanically deboned chicken meat frankfurter-type emulsions inoculated with Clostridium botulinum spores, or a combination of ii and iii, were temperature abuse at 27 degrees C. Spore germination and total microbial growth were followed and examined at specified times and until toxic samples were detected. The spores germinated within 3 days in both control and nitrite (20, 40 and 156 micrograms/g) treatments. Sorbic acid (0.2%) alone or in combination with nitrite (20, 40, and 156 micrograms/g) significantly (P less than 0.05) inhibited spore germinations. No significant germination was recorded until toxic samples were detected. A much longer incubation period was necessary for toxin to be formed in nitrite-sorbic acid combination treatments as contrasted with controls or nitrite and sorbic acid used individually. Total growth was not affected by the presence of nitrite, whereas sorbic acid appeared to depress it. Possible mechanisms explaining the effects of nitrite and sorbic acid on spore germination and growth are postulated.

Animals

[Inhibitory effect of a number of substances on manifestation of the embryotoxic and teratogenic effects of methylurea and sodium nitrite].

Embryos died and a teratogenic effect followed combined intragastric administration of methylurea (MU) and sodium nitrite (SN) to rats on the 9th day of pregnancy; this was caused by the endogenous synthesis of nitroso-methylurea which produced a pathogenic action. Ascorbic acid and urotropine completely blocked the possibility of manifestation of the embryotoxic and teratogenic effect occuring after combined administration of MU and SN. Sodium sulfomate decreased the embryotoxic and partially the teratogenic effect considerably, whereas urea failed to prevent the expression of the harmful effect of MU and SN on the embryo.

Abnormalities, Drug-Induced

Quantification of the inhibitory effect of eriochrome black and sodium nitrite on non-specific immunofluorescent staining.

To evaluate non-specific staining (NSS) of animal tissues by FITC-labelled immunoglobulins a model system was developed. HeLa cells were treated with labelled antisalmonella globulins and the fluorescence intensity of the cells was determined quantitatively by means of a fibre optic probe system. This system was used to determine the optimal treatment conditions (adequate concentrations, duration of treatment) using the two NSS-reducing agents eriochrome black and sodium nitrite. Approximately the same inhibitory effects (40-50 per cent using nitrite; about 85 per cent using eriochrome black) were obtained by conjugates of different F/P ratio values. The fibre optic probe system was also used to determine the effects of the above-mentioned agents on the NSS of liver sections. In this system, the NSS was strongly reduced by eriochrome black whereas nitrite treatment did not induce any inhibitory effect. The applicability of nitrite and eriochrome black as NSS-reducing agents was further demonstrated by the fact that they had no influence on the specific fluorescence intensity of salmonella bacteria. The effect of eriochrome black was also studied in clinical specimens infected with salmonella or tularemia bacteria.

Animals

Transplacental action of sodium nitrite on embryonic cells of Syrian golden hamster.

Hamster embryos were treated with various doses of NaNO2 in utero, by its oral administration to the mothers, and then the embryonic cells were examined for micronucleus formation, chromosomal aberrations, morphological or malignant transformation and drug-resistant mutations. For induction of resistant mutations, the cells were cultured in normal medium for 72 h, and then selected in media containing 8-azaguanine (10 or 20 microgram/ml) or 1 mM ouabain. This treatment with NaNO2 caused marked dose-dependent induction of 8-azaguanine- and ouabain-resistant mutations. Cultured embryonic fibroblasts in the resting state also showed a marked dose-dependent increase in micronucleus formation but not an increase in chromosomal aberrations. This treatment also caused morphological and neoplastic transformation of the cells. Transplacental oral treatment with DMN, as a positive control, caused changes of similar extent in biological effects of embryonic fibroblasts, and in addition it caused chromosomal aberrations in metaphase plates. On the contrary, transplacental oral application of NaNO2 did not induce any biological change in cultured embryonic fibroblasts.

Abnormalities, Drug-Induced

Formation of methylnitrosocyanamide from methylguanidine and sodium nitrite in simulated gastric juice and in stomachs of rats: quantitative estimation by a mutagenicity assay.

The formation of methylnitrosocyanamide (MNC), a carcionogenic N-nitroso compound, from methylguanidine (MG) and NaNO2 in simulated gastric juice (SGJ) and in the stomachs of rats was quantitatively investigated. With a reverse mutation assay in which a tester strain of Salmonella typhimurium was used, MNC formation was shown to increase linearly for about 40--60 minutes after the incubation of MG with NaNO2 in SGJ. However, it decreased rapidly thereafter. The initial rate of MNC formation was directly proportional to the initial molar ratio of MG to NaNO2, but the yields of MNC depended only on the amount of MG added and were fairly constant (0.3--0.5% of the initial MG). MNC did not form at a pH above 2.5 or in the presence of 2% casein in SGJ at pH 1.2. It decomposed rapidly in SGJ at pH 1.2 with a half-life of approximately 2 minutes, whereas it was stable in phosphate buffer at pH 7.0. Following concurrent administration of MG and NaNO2 via stomach tube, MNC formation was detected in the pylorus-ligated stomachs of rats preconditioned with a casein-free dextrin diet but not in those of rats preconditioned with a casein-containing or synthetic diet. The yields of MNC observed 40--60 minutes after administration of reactants ranged from 0.02 to 0.05% of the initial MG. The possible environment significance of MNC formation in vivo was considered.

Animals