Showing papers on "Nitrite published in 1972"

Ascorbate-Nitrite Reaction: Possible Means of Blocking the Formation of Carcinogenic N-Nitroso Compounds

Abstract: The formation of carcinogenic N-nitroso compounds by the chemical reaction between nitrous acid and oxytetracycline, morpholine, piperazine, N-methylaniline, methylurea, and (in some experiments) dimethylamine was blocked by ascorbic acid. The extent of blocking depended on the compound nitrosated and on the experimental conditions. Urea and ammonium sulfamate were less effective as blocking agents. The possibility of in vivo formation of carcinogenic N-nitroso compounds from drugs could be lessened by the combination of such drugs with the ascorbic acid.

Identification of the sources of nitrous oxide produced by oxidative and reductive processes in Nitrosomonas europaea.

Abstract: 1. Cells of Nitrosomonas europaea produced N2O during the oxidation of ammonia and hydroxylamine. 2. The end-product of ammonia oxidation, nitrite, was the predominant source of N2O in cells. 3. Cells also produced N2O, but not N2 gas, by the reduction of nitrite under anaerobic conditions. 4. Hydroxylamine was oxidized by cell-free extracts to yield nitrite and N2O aerobically, but to yield N2O and NO anaerobically. 5. Cell extracts reduced nitrite both aerobically and anaerobically to NO and N2O with hydroxylamine as an electron donor. 6. The relative amounts of NO and N2O produced during hydroxylamine oxidation and/or nitrite reduction are dependent on the type of artificial electron acceptor utilized. 7. Partially purified hydroxylamine oxidase retained nitrite reductase activity but cytochrome oxidase was absent. 8. There is a close association of hydroxylamine oxidase and nitrite reductase activities in purified preparations.

Carcinogenic Nitrosamines formed by Drug/Nitrite Interactions

Abstract: NITROSAMINES are compounds with broad carcinogenic activity in many animal species, but have seldom been detected in the environment in significant quantities. Man may nevertheless be exposed to nitrosamines formed in vivo from ingested nitrite and secondary amines1–3. Nitrite is a common constituent of the diet, as are several secondary amines4. Since tertiary amines can also react with nitrite5 in the mildly acid conditions of the mammalian stomach, the exposure of man to the many tertiary nitrogen compounds which are drugs6 must also be considered.

Heterotrophic Nitrification by Arthrobacter sp

Abstract: Arthrobacter sp. isolated from sewage oxidized ammonium to hydroxylamine, a bound hydroxylamine compound, a hydroxamic acid, a substance presumed to be a primary nitro compound, nitrite, and nitrate. The concentration of free hydroxylamine-nitrogen reached 15 mug/ml. The identification of hydroxylamine was verified by mass spectrometric analysis of its benzophenone oxime derivative. The bound hydroxylamine was tentatively identified as 1-nitrosoethanol on the basis of its mass spectrum, chemical reactions, and infrared and ultraviolet spectra. Hydroxylamine formation by growing cells was relatively independent of pH, but the accumulation of nitrite was strongly favored in alkaline solutions. The formation of hydroxylamine but not nitrite was regulated by the carbon to nitrogen ratio of the medium. The hydroxamic acid was the dominant product of nitrification in iron-deficient media, but hydroxylamine, nitrite, and 1-nitrosoethanol formation was favored in iron-rich solutions. Heterotrophic nitrification by Arthrobacter sp. was not inhibited by several compounds at concentrations which totally inhibited autotrophic nitrification.

Estimation of Steam-Volatile N-Nitrosamines in Foods at the 1 µg/kg Level

Abstract: SINCE the discovery1 of the hepatotoxic and carcinogenic properties of N-nitrosodimethylamine (DMN), these properties have been demonstrated in a variety of N-nitroso compounds2–5. The effect of feeding mink with herring meal treated with excessive amounts of nitrite is to induce a liver disease6, and DMN has been isolated as the hepatotoxic factor7,8. Various methylamines present in the herring meal, especially dimethylamine and trimethylamine, were found to be responsible for the formation of DMN. Although the concentration of nitrite used in the processing of the fish meal were not typical of normal commercial food preservation practice, it is essential that any potential nitrosamine hazard deriving from the use of nitrites and nitrates in the preserving and processing of foodstuffs should be evaluated.

Consequences of banding nitrogen fertilizers in soil

Abstract: An account is given of the interactions which occur when urea or ammonium sulphate is banded in a clay soil. The spatial distributions of ammonium, nitrate, and nitrite around the band are given as functions of time and are discussed in relation to results from a series of incubations of homogeneous mixtures of various nitrogen compounds and soil. The diffusion of the banded fertilizers and their products through the soil presents the nitrifying organisms with a wide range of environments. The patterns of nitrification are therefore complicated. Nevertheless, they are explicable in terms of the main results of the incubations which were that (a) nitrification was completely inhibited if the osmotic suction of the soil solution was higher than 10 bars, if the ammonium-N concentration in the soil solution was above 3000 ppm, or if the pH was greater than 8, (b) nitrite accumulated if the pH was between 7 and 8, (c) nitrate accumulated if the pH was less than 7, and (d) above a minimum concentration of fertilizer the rate of nitrate formation was independent of the concentration unless the latter was so high that either pH, osmotic suction or ammonium concentration became inhibitory.

Carcinogen Dimethylnitrosamine produced in vivo from Nitrite and Aminopyrine

Abstract: IN experimental conditions, nitrite can interact with secondary amines in the rodent stomach at mildly acid pH to form nitrosamines1–4, a large number of which are potent carcinogens5. As tertiary amines also react in this way6, we have examined the analgesic aminopyrine, 4-dimethylaminoantipyrine (pyramidon), as being representative of many commonly used tertiary amine drugs.

Nitrous oxide release by soil fungi

Abstract: Fusarium oxysporum and F. solani reduced nitrite in growing cultures and in resting cell experiments at low oxygen tensions with the simultaneous release of nitrous oxide. Nitrate, however, was not transformed during growth under aerobic or partially anaerobic conditions. No nitrous oxide was generated from nitrate, ammonium or hydroxylamine by resting cells. There are no plausible explanations for the physiological reaction involved in the release of nitrous oxide, but the finding that soil fungi are able to volatilize nitrogen implies a new factor in the disappearance of nitrogen from soil.

Effect of sodium nitrite concentration on n-nitrosodimethylamine formation in frankfurters

Abstract: The effect of nitrite concentration on N-nitrosodimethylamine (DMNA) formation using frankfurter emulsion was investigated. Sodium nitrite was usually added to the emulsion to give levels of 150, 750, 1050, 1500 and 2500 mg/kg of meat. The frankfurters were cooked with light smoke for either 2 or 4 hr. DMNA was determined in all samples by GLC with an alkali flame ionization detector and confirmed by GLC-MS when sufficient amounts were present. Residual nitrite analysis indicated that about one-half of the sodium nitrite added was still present after processing. 19 μg DMNA per kg meat was found in frankfurters that contained 2500 mg sodium nitrite per kg of meat and processed for 2 hr. Indications of DMNA in levels of 3–14 μg/kg meat were obtained with frankfurters containing 750–1500 mg sodium nitrite per kg meat and processed for either 2 or 4 hr depending on the nitrite level. There appeared to be some tendency for an increase in DMNA formation on increasing processing time.

Nitrogen metabolism of aquatic organisms. ii. the assimilation of nitrate, nitrite, and ammonia by biddulphia aurita1

Abstract: SUMMARY Biddulphia aurita, a centric diatom, can grow on either nitrate, nitrite, or ammonia as its sole nitrogen, source. Cells remove ammonium nitrogen from the medium 2.3–2.4 times faster than either nitrate or nitrite nitrogen and, when grown for 24 hr in the ammonium medium, contain higher levels of non-protein nitrogen than cells grown in the nitrate or nitrite medium for the same period of time. The nitrogenous compounds in the nonprotein nitrogen fraction from cells grown in the nitrate, nitrite, or ammonium medium contain the same level of soluble-free amino nitrogen, combined amino nitrogen, and ammonium nitrogen. The high level of soluble nonprotein nitrogen in the medium of the cells grown in the ammonium medium is due to soluble amide nitrogen which represents 18% of the total soluble nitrogen present in these cells, whereas it represents only 2% in cells from the nitrite medium, and its level is negligible in cells from the nitrate medium. Cells grown in the nitrate medium have both nitrate- and nitrite-reductase activity. Cells grown in the nitrite medium have only nitrite-reductase activity in significant levels, while cells grown in the ammonium medium lack both enzymes.

Nitrate Reductase of Rice Seedlings and Its Induction by Organic Nitro-Compounds

Abstract: Nitrate simultaneously induced NADH- and NADPH-nitrate reductase activities in rice seedlings. Chloramphenicol, other organic nitro-compounds such as o-nitroaniline and 2,4-dinitrophenol and nitrite also induced nitrate reductase in rice seedlings. The nitrate- or nitrite-induced nitrate reductase could accept electrons more efficiently from NADH than NADPH. However, when this enzyme was induced by organic nitro-compounds, it could accept electrons more efficiently from NADPH than NADH.

Mechanism of Nitrification by Arthrobacter sp

Abstract: Resting cells of Arthrobacter sp. excrete as much as 60 μg of hydroxylamine-nitrogen per ml when supplied with ammonium. An organic carbon source in abundant supply is necessary for the oxidation. Resting cells oxidize hydroxylamine to nitrite and 1-nitrosoethanol, the former accumulating only when an exogenous carbon source is available. Cell-free extracts contain an enzyme catalyzing the formation of hydroxylamine from acetohydroxamic acid, a hydroxylamine-nitrite oxido-reductase, and an enzyme producing nitrite and nitrate from various primary nitro compounds. Nitrite is not produced from hydroxylamine by the extracts, but 1-nitrosoethanol is formed from hydroxylamine in the presence of acetate. 1-Nitrosoethanol is also produced from acetohydroxamic acid by these preparations. Nitrite was formed from hydroxylamine, however, by extracellular enzymes excreted by the bacterium.

Nitrosamide Formation In Vivo: Induction of Lung Adenomas in Swiss Mice by Concurrent Feeding of Nitrite and Methylurea or Ethylurea

Abstract: Swiss mice were treated For 6 months with methylurea (5.36 g/kg Food) or ethylurea (6.36 g/kg Food) together with sodium nitrite (1.0 g/Iiter drinking water). In both groups, more than 4 lung adenomas/mouse were induced. The alkyl urea-plus-nitrite groups also had a small increase in malignant lymphomas. Similar treatment with methylurea or ethylurea alone had no effect. The results indicate that the lung adenomas were induced by methylnitrosourea and ethylnitrosourea, Formed by in vivo nitrosation of the corresponding alkylureas. The possible public health implications of ureide nitrosation in vivo are discussed.-J Nat Cancer Inst 48: 1311-1315, 1972.

Variable Ammonia Production Among Smooth and Rough Strains of Pseudomonas pseudomallei: Resemblance to Bacteriocin Production

Abstract: The colonial morphology of some strains of Pseudomonas pseudomallei was correlated with certain biochemical and physiological traits. After 3 days of growth on Wahba or heart infusion agars, smooth-colony strains generated toxic amounts of ammonia. Under the same conditions, the rough strains simultaneously produced oxalic acid which decreased the inhibitory concentration of ammonia. The ammonia-ammonium concentrations in smooth cultures exhibited certain bacteriocin-like characteristics. An unusually stable, smooth strain (strain 165) was chosen to compare and emphasize any differences with typical, rough strain 7815. Three-day-old smooth cultures grown on Wahba agar containing 3% (w/v) glycerol demonstrated ammonia toxicity. The substitution of glucose for glycerol completely obviated this toxicity. In highly aerated Wahba broth containing glucose, the amount of ammonia found in strain 165 smooth cultures and the amount of oxalic acid found in strain 7815 rough cultures were greatly reduced. In Difco nitrate broth smooth strain 165 did not form gas, and it reduced nitrate to nitrite only. Strain 7815 produced a gas and reduced both nitrate and nitrite.

The anaerobic degradation of aromatic compounds by a denitrifying bacterium. Radioisotope and mutant studies.

Abstract: 1. Pseudomonas PN-1, grown anaerobically on a benzoate-nitrate medium, produced 14CO2 from either carboxyl-labelled or uniformly ring-labelled 14C-benzoate upon aerobic or anaerobic incubation. Anaerobic catabolism required either nitrite or nitrous oxide as terminal electron acceptor. Twice as much 14CO2 was formed anaerobically. 14CO2 was produced in equal amounts from carboxyllabelled or ring-labelled 14C-benzoate on aerobic incubation whereas anaerobically more 14CO2 was released from carboxyl-labelled 14C-benzoate. 2. Cells grown anaerobically on p-hydroxybenzoate-nitrate medium released 14CO2 from 14C-benzoate only on anaerobic incubation with nitrite or nitrous oxide. More 14CO2 was produced from 7-14C-benzoate than ring-labelled 14C-benzoate. No 14CO2 was formed aerobically even with nitrite added. Protocatechuate or catechol did not trap any radioactivity when added to cells oxidizing ring-labelled 14-benzoate anaerobically. 3. A mutant, induced by nitrosoguanidine treatment, was isolated which grew aerobically but not anaerobically on p-hydroxybenzoate.

Alkoxide-ion attack at the nitrosyl group of [IrCl3(NO)(PPh3)2]+ to give alkyl nitrite complexes of iridium(III)

Abstract: The cationic nitrosyls, [IrCl3(NO)L2]+(L = PPh3, AsPh3) react with alcohols to give neutral iridium(III) complexes containing bound alkyl nitrites, IrCl3(RONO)L2(R = Me, Et, Pr). These reactions parallel the formation of complexes containing alkoxycarbonyl groups as ligands by alkoxide-ion attack on cationic carbonyl complexes. The nitrite complexes revert to the parent nitrosyls with acids and it is suggested that this reaction bears upon the mechanism of formation of nitrosyl complexes in the frequently used preparations which make use of alkyl nitrites, N-nitroso-reagents, nitrous acid, and NO+ salts. New routes to the dinitrosyl cations, [Ir(NO)2L2]+, and preparations of Ir(NO)(AsPh3)3, are also reported.

Some Chemical and Microbiological Observations in the Pacific Ocean off the Hawaiian ISLANDS1

Abstract: Simultaneous chemical and microbial analyses of the water column were made at 33 stations off the leeward Hawaiian Islands. The overall distribution of oxygen, nitrate, and pH was similar at all stations located more than 5 km offshore. These parameters were closely correlated and also correlated with nitrifying and nitrate-reducing activity in the water column. The distribution of nitrite and ammonium did not correlate with the oxygen distribution. A nitrite band was consistently found in the lower portion of the photic zone and appeared to have originated from reduction of nitrate rather than from oxidation of ammonium. The distribution of aerobic and anaerobic bacteria was regulated by the amount of available organic nutrients and not by the oxygen concentration.

The role of light in nitrite reduction; Studies with leaf discs.

Abstract: The reduction of nitrite by leaf discs has been studied. In short term experiments the reduction is markedly stimulated by light, but is not affected by the absence of oxygen or carbon dioxide from the gas phase. Carbon dioxide assimilation is more sensitive than nitrite reduction to 3-(3′,4′-dichloro-)-1,1-dimethyl urea (DCMU) inhibition. Uncouplers such as carbonyl cyanide m-chlorophenyl-hydrazone (CCCP) do not inhibit nitrite reduction although dinitrophenol (DNP) has a small effect.

Increased Denitrification in Soils by Additions of Sulfur as an Energy Source

Abstract: Denitrification rates were studied in four large soil columns using Hanford sandy loam and Moreno silty clay loam soils. One column of each soil was amended with sulfur to serve as an energy source for the bacterium Thiobacillus denitrificans. Limestone was also added as a pH buffer. The other column of each soil was left untreated to serve as a control. A solution of Ca(NO₃)₂ containing 425 ppm NO₃-N was perfused continuously through the columns. The columns were monitored periodically at depths of 10, 30, 50, 70, and 90 cm for nitrate, nitrite, redox potential (Eₕ) and microbial numbers. Highly anaerobic conditions developed in all columns as was evidenced by low Eₕ values at each depth. All of the nitrate was reduced in each column, and nitrates penetrated to lower depths in the untreated columns. Nitrite concentrations were found to be negligible. Denitrification rate constants were established as 0.174, 0.520, 0.186, and 1.426 days⁻¹, for the Hanford-untreated, Hanford-treated, Morneo-untreated, and Moreno-treated columns, respectively. Sulfur additions to field soils which are low in microbial energy sources could be an effective method of reducing the nitrate level in waters percolating through the profile.