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Sample records for calcium nitrite

  1. Effect of Calcium Nitrate and Sodium Nitrite on the Rebar Corrosion of Medium Carbon Steel in Seawater and Cassava Fluid

    OpenAIRE

    Adamu, M; Umoru, LE; Ige, OO

    2014-01-01

    Inhibitors are regularly used as one of the principal prevention and control techniques in reinforcement corrosion. Hence this study investigates the effect of calcium nitrate and sodium nitrite inhibitors on the rebar corrosion of medium carbon steel in seawater and cassava fluid with a view to determining inhibitive potentials of the different inhibitors in the two media. Gravimetric and voltametric techniques were employed in this study and a total of forty-five corrosion coupons of differ...

  2. Nitrite-cured color and phosphate-mediated water binding of pork muscle proteins as affected by calcium in the curing solution.

    Science.gov (United States)

    Zhao, Jing; Xiong, Youling L

    2012-07-01

    Calcium is a mineral naturally present in water and may be included into meat products during processing thereby influencing meat quality. Phosphates improve myofibril swelling and meat water-holding capacity (WHC) but can be sensitive to calcium precipitation. In this study, pork shoulder meat was used to investigate the impact of calcium at 0, 250, and 500 ppm and phosphate type [sodium pyrophosphate (PP), tripolyphosphate (TPP), and hexametaphopshate (HMP)] at 10 mM on nitrite-cured protein extract color at various pH levels (5.5, 6.0, and 6.5) and crude myofibril WHC at pH 6.0. Neither calcium nor phosphates present in the curing brines significantly affected the cured color. Increasing the pH tended to promote the formation of metmyoglobin instead of nitrosylmyoglobin. The ability of PP to enhance myofibril WHC was hampered (P meat products. Although not affecting nitrite-cured color, calcium hampers the efficacy of phosphates to promote water binding by muscle proteins, underscoring the importance of water quality for brine-enhanced meat products. © 2012 Institute of Food Technologists®

  3. Assessment of high performance concrete containing fly ash and calcium nitrite based corrosion inhibitor as a mean to prevent the corrosion of reinforcing steel

    International Nuclear Information System (INIS)

    Montes-García, P; Jiménez-Quero, V; López-Calvo, H

    2015-01-01

    This research analyses the effectiveness of the water-to-cement ratio (w/c), fly ash and a calcium nitrite based corrosion inhibitor to prevent the corrosion of reinforcing steel embedded in high performance concrete. The interactive effect between the inhibitor and fly ash was evaluated because the occurrence of a negative effect when both ingredients are added together in a concrete mixture has been reported. All the concrete mixtures studied in this investigation had 8.2% of silica fume. Twenty seven prismatic concrete specimens were fabricated with dimensions of 55 × 230 × 300 mm each containing two steel rods embedded for the purpose of corrosion monitoring. The specimens were exposed to a simulated marine environment with two daily cycles of wetting and drying for one year. To evaluate the deterioration of the specimens corrosion potentials and linear polarization resistance tests were carried out. The results indicate that the use of a low w/c, the addition of fly ash and the addition of the corrosion inhibitor contributed to the reduction of the corrosion of steel in the concrete specimens. The results further suggest that the combination of fly ash and corrosion inhibitor does not promote the deterioration of the concrete matrix

  4. Calcium

    Science.gov (United States)

    ... You can get decent amounts of calcium from baked beans, navy beans, white beans, and others. Canned fish. You're in luck if you like sardines and canned salmon with bones. Almond milk. Working Calcium Into Your ...

  5. A new electrochemical sensor for highly sensitive and selective detection of nitrite in food samples based on sonochemical synthesized Calcium Ferrite (CaFe2O4) clusters modified screen printed carbon electrode.

    Science.gov (United States)

    Balasubramanian, Paramasivam; Settu, Ramki; Chen, Shen-Ming; Chen, Tse-Wei; Sharmila, Ganapathi

    2018-08-15

    Herein, we report a novel, disposable electrochemical sensor for the detection of nitrite ions in food samples based on the sonochemical synthesized orthorhombic CaFe 2 O 4 (CFO) clusters modified screen printed electrode. As synthesized CFO clusters were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformer infrared spectroscopy (FT-IR), Thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and amperometry (i-t). Under optimal condition, the CFO modified electrode displayed a rapid current response to nitrite, a linear response range from 0.016 to 1921 µM associated with a low detection limit 6.6 nM. The suggested sensor also showed the excellent sensitivity of 3.712 μA μM -1  cm -2 . Furthermore, a good reproducibility, long-term stability and excellent selectivity were also attained on the proposed sensor. In addition, the practical applicability of the sensor was investigated via meat samples, tap water and drinking water, and showed desirable recovery rate, representing its possibilities for practical application. Copyright © 2018 Elsevier Inc. All rights reserved.

  6. Respiration of Nitrate and Nitrite.

    Science.gov (United States)

    Cole, Jeffrey A; Richardson, David J

    2008-09-01

    Nitrate reduction to ammonia via nitrite occurs widely as an anabolic process through which bacteria, archaea, and plants can assimilate nitrate into cellular biomass. Escherichia coli and related enteric bacteria can couple the eight-electron reduction of nitrate to ammonium to growth by coupling the nitrate and nitrite reductases involved to energy-conserving respiratory electron transport systems. In global terms, the respiratory reduction of nitrate to ammonium dominates nitrate and nitrite reduction in many electron-rich environments such as anoxic marine sediments and sulfide-rich thermal vents, the human gastrointestinal tract, and the bodies of warm-blooded animals. This review reviews the regulation and enzymology of this process in E. coli and, where relevant detail is available, also in Salmonella and draws comparisons with and implications for the process in other bacteria where it is pertinent to do so. Fatty acids may be present in high levels in many of the natural environments of E. coli and Salmonella in which oxygen is limited but nitrate is available to support respiration. In E. coli, nitrate reduction in the periplasm involves the products of two seven-gene operons, napFDAGHBC, encoding the periplasmic nitrate reductase, and nrfABCDEFG, encoding the periplasmic nitrite reductase. No bacterium has yet been shown to couple a periplasmic nitrate reductase solely to the cytoplasmic nitrite reductase NirB. The cytoplasmic pathway for nitrate reduction to ammonia is restricted almost exclusively to a few groups of facultative anaerobic bacteria that encounter high concentrations of environmental nitrate.

  7. Dependence of nitrite oxidation on nitrite and oxygen in low-oxygen seawater

    Science.gov (United States)

    Sun, Xin; Ji, Qixing; Jayakumar, Amal; Ward, Bess B.

    2017-08-01

    Nitrite oxidation is an essential step in transformations of fixed nitrogen. The physiology of nitrite oxidizing bacteria (NOB) implies that the rates of nitrite oxidation should be controlled by concentration of their substrate, nitrite, and the terminal electron acceptor, oxygen. The sensitivities of nitrite oxidation to oxygen and nitrite concentrations were investigated using 15N tracer incubations in the Eastern Tropical North Pacific. Nitrite stimulated nitrite oxidation under low in situ nitrite conditions, following Michaelis-Menten kinetics, indicating that nitrite was the limiting substrate. The nitrite half-saturation constant (Ks = 0.254 ± 0.161 μM) was 1-3 orders of magnitude lower than in cultivated NOB, indicating higher affinity of marine NOB for nitrite. The highest rates of nitrite oxidation were measured in the oxygen depleted zone (ODZ), and were partially inhibited by additions of oxygen. This oxygen sensitivity suggests that ODZ specialist NOB, adapted to low-oxygen conditions, are responsible for apparently anaerobic nitrite oxidation.

  8. Nitrates and nitrites intoxications’ management

    Directory of Open Access Journals (Sweden)

    Alexandra Trif

    2007-12-01

    Full Text Available The study pointed out the major sources for clinical and subclinical intoxications with nitrates/nitrites (drinking water and nitrates containing fertilizers, circumstances that determine fertilizers to became sources of intoxication (excessive fertilization/consecutive high level of nitrates in fodders, free access of animals to the fertilizers, administration into the diet instead of natrium chloride, factors that determine high nitrates accumulation in fodders despite optimal fertilization (factors related to the plants, soil, clime, harvest methods, storage, agrotechnical measures, nitrates/nitrites toxicity (over 45 ppm nitrates in drinking water, over 0.5 g nitrate/100 g D.M fodder/diet, the factors that influence nitrates/nitrites toxicity ( species, age, rate of feeding, diet balance especially energetically, pathological effects and symptoms (irritation and congestions on digestive tract, resulting diarrhoea, transformation of hemoglobin into methemoglobin determining severe respiratory insufficiency, vascular collapse, low blood pressure inthe acute nitrates intoxication; hypotiroidism, hypovitaminosis A, reproductive disturbances(abortion, low rate of fertility, dead born offspring, diarrhoea and/or respiratory insufficiency in new born e.g. calves, immunosuppression, decrease of milk production in chronic intoxication. There were presented some suggestions concerning management practices to limit nitrate intoxication (analyze of nitrates/nitrites in water and fodders, good management of the situation of risk ,e .g. dilution of the diet with low nitrate content fodders, feeding with balanced diet in energy, protein, minerals and vitamins, accommodation to high nitrate level diet, avoid grazing one week after a frost period, avoid feeding chop green fodders stored a couple of days, monitoring of health status of animals fed with fodders containing nitrates at risk level, a.o..

  9. Dietary Nitrite: from menace to marvel

    Directory of Open Access Journals (Sweden)

    Nathan S. Bryan

    2016-11-01

    Full Text Available The health benefits of nitrite are now indisputable when administered in a clinical setting for specific diseases. Currently, most published reports identify the production of nitric oxide (NO as the mechanism of action for nitrite. Basic science, in addition to clinical studies, demonstrate that nitrite and/or nitrate cannot restore NO homeostasis as an endothelium independent source of NO that may be a redundant system for endogenous NO production. Nitrate must first be reduced to nitrite by oral commensal bacteria; nitrite can then be further reduced to NO along the physiological oxygen gradient. But despite decades of rigorous research on sodium nitrate’s safety and efficacy as a curing agent, sodium nitrite is still regarded by many as a toxic undesirable food additive. However, research within the biomedical science community has revealed enormous therapeutic benefits of nitrite which are being developed as novel therapies for conditions associated with nitric oxide insufficiency. Thus, this review will highlight the fundamental biochemistry of nitrite in human physiology and provide evidence that nitrite be considered an essential nutrient. Foods or diets enriched with nitrite can have profound positive health benefits.

  10. Boletus edulis Nitrite Reductase Reduces Nitrite Content of Pickles and Mitigates Intoxication in Nitrite-intoxicated Mice.

    Science.gov (United States)

    Zhang, Weiwei; Tian, Guoting; Feng, Shanshan; Wong, Jack Ho; Zhao, Yongchang; Chen, Xiao; Wang, Hexiang; Ng, Tzi Bun

    2015-10-08

    Pickles are popular in China and exhibits health-promoting effects. However, nitrite produced during fermentation adversely affects health due to formation of methemoglobin and conversion to carcinogenic nitrosamine. Fruiting bodies of the mushroom Boletus edulis were capable of inhibiting nitrite production during pickle fermentation. A 90-kDa nitrite reductase (NiR), demonstrating peptide sequence homology to fungal nitrite reductase, was isolated from B. edulis fruiting bodies. The optimum temperature and pH of the enzyme was 45 °C and 6.8, respectively. B. edulis NiR was capable of prolonging the lifespan of nitrite-intoxicated mice, indicating that it had the action of an antidote. The enzyme could also eliminate nitrite from blood after intragastric administration of sodium nitrite, and after packaging into capsule, this nitrite-eliminating activity could persist for at least 120 minutes thus avoiding immediate gastric degradation. B. edulis NiR represents the first nitrite reductase purified from mushrooms and may facilitate subsequent applications.

  11. Nitrates, Nitrites, and Health. Bulletin 750.

    Science.gov (United States)

    Deeb, Barbara S.; Sloan, Kenneth W.

    This review is intended to assess available literature in order to define the range of nitrate/nitrite effects on animals. Though the literature deals primarily with livestock and experimental animals, much of the contemporary research is concerned with human nitrite intoxication. Thus, the effects on man are discussed where appropriate. Some of…

  12. Nitrite, nitrite alternatives, and the control of Clostridium botulinum in cured meats.

    Science.gov (United States)

    Pierson, M D; Smoot, L A

    1982-01-01

    Historically, nitrite has been a component of meat-curing additives for several centuries. In recent years the safety of nitrite as an additive in cured meats has been questioned mainly because of the possible formation of carcinogenic nitrosamines. Nitrite has many important functions in meat curing including its role in color development, flavor, antioxidant properties, and antimicrobial activity. The inhibition of Clostridium botulinum growth and toxin production is an especially important antimicrobial property of nitrite. This review discusses the effects of processing, curing ingredients (especially nitrite), and storage of cured meats in relation to the control of C. botulinum. If nitrite is eliminated from cured meats or the level of usage decreased, then alternatives for the antibotulinal function of nitrite need to be considered. Several potential alternatives including sorbates, parabens, and biological acidulants are discussed.

  13. Nitrite-dependent vasodilation is facilitated by hypoxia and is independent of known NO-generating nitrite reductase activities

    DEFF Research Database (Denmark)

    Fago, Angela; Dalsgaard, Thomas; Fago, Angela

    2007-01-01

    is largely intrinsic to the vessel and that under hypoxia physiological nitrite concentrations are sufficient to induce NO-mediated vasodilation independently of the nitrite reductase activities investigated here. Possible reaction mechanisms for nitrite vasoactivity, including formation of S...

  14. Radiation preservation of low nitrite bacon

    International Nuclear Information System (INIS)

    Singh, H.

    1988-01-01

    Sodium nitrite, a key ingredient of the mix used to cure bacon and other meats, promotes and fixes bacon's characteristic pink color, inhibits lipid peroxidation and prevents growth of micro-organisms, particularly Clostridium botulinum spores. Unfortunately, nitrite leads to the formation of carcinogenic nitrosamines in bacon. This has led to a search for alternatives to the use of nitrite. Irradiation with reduced level of nitrite is a promising alternative. Radurization of bacon containing 20 to 40 mg/kg of nitrite in evacuated packages, irradiated and stored at 4 0 C, gives a product with good organoleptic qualities and extended shelf life of > 90 days, as opposed to ∼ 30 days for the conventionally treated bacon. Radappertization of bacon containing 20 mg/kg of nitrite at a dose of about 30 kGy, irradiated at temperature of -20 0 or lower in evacuated packages, results in a product that is shelf stable at room temperature for months to years. It has organoleptic qualities comparable to commercial bacon in terms of color, flavor, odor and texture. Irradiation also reduces the nitrite and preformed nitrosamines present in bacon. Various aspects of preservation of bacon are reviewed in this report with emphasis on radiation processing. (author)

  15. Fluorometric determination of nitrite with 4-hydroxycoumarin

    Energy Technology Data Exchange (ETDEWEB)

    Ohta, T.; Arai, Y.; Takitani, S.

    1986-12-01

    A simple, sensitive, and reproducible fluorometric method for determination of nitrite has been developed. This method is based on the nitrosation of 4-hydroxycoumarin in acidic medium and subsequent reduction to 3-amino-4-hydroxy-coumarin, which is fluorescent in alkaline medium. The fluorescence intensity is proportional to the nitrite concentration in the range of 3 ng/mL to 1 ..mu..g/mL in the sample solution, with a relative standard deviation of 0.5% (50 ng/mL). The method has been applied to the determination of nitrite in saliva.

  16. Nitrite disrupts multiple physiological functions in aquatic animals

    DEFF Research Database (Denmark)

    Jensen, Frank Bo

    2003-01-01

    be inhibited, while changes in ammonia and urea levels and excretion rates reflect an influence of nitrite on nitrogen metabolism. Detoxification of nitrite occurs via endogenous oxidation to nitrate, and elimination of nitrite takes place both via gills and urine. The susceptibility to nitrite varies between...... nitrite-induced vasodilation (possibly via nitric oxide generated from nitrite) that is countered by increased cardiac pumping to re-establish blood pressure. Nitrite can form and/or mimic nitric oxide and thereby interfere with processes regulated by this local hormone. Steroid hormone synthesis may...

  17. Dietary nitrates, nitrites, and cardiovascular disease.

    Science.gov (United States)

    Hord, Norman G

    2011-12-01

    Dietary nitrate (NO(3)), nitrite (NO(2)), and arginine can serve as sources for production of NO(x) (a diverse group of metabolites including nitric oxide, nitrosothiols, and nitroalkenes) via ultraviolet light exposure to skin, mammalian nitrate/nitrite reductases in tissues, and nitric oxide synthase enzymes, respectively. NO(x) are responsible for the hypotensive, antiplatelet, and cytoprotective effects of dietary nitrates and nitrites. Current regulatory limits on nitrate intakes, based on concerns regarding potential risk of carcinogenicity and methemoglobinemia, are exceeded by normal daily intakes of single foods, such as soya milk and spinach, as well as by some recommended dietary patterns such as the Dietary Approaches to Stop Hypertension diet. This review includes a call for regulatory bodies to consider all available data on the beneficial physiologic roles of nitrate and nitrite in order to derive rational bases for dietary recommendations.

  18. Experimental Study of Leaching and Penetration of Nitrite ions in Nitrite-type Repair Materials on the Surface of Concrete

    Directory of Open Access Journals (Sweden)

    Masumi Inoue

    2017-01-01

    Full Text Available This study aimed to clarify the leaching properties of nitrite ions in nitrite-type repair materials exposed to rainfall. Repaired concrete specimens were prepared for leaching tests using a lithium nitrite solution, and the amounts of leaching and penetration of nitrite ions were measured under simulated rainfall. The results demonstrated that the amount of leaching could be controlled by using polymer cement paste and mortar surface coatings containing lithium nitrite solution, and by using polymer cement mortar surface coatings following direct lithium nitrite solution coatings. Furthermore, the amount of nitrite ion leaching in all cases was lower than the discharge standard value established by the water pollution control law.

  19. Calcium supplements

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007477.htm Calcium supplements To use the sharing features on this page, please enable JavaScript. WHO SHOULD TAKE CALCIUM SUPPLEMENTS? Calcium is an important mineral for the ...

  20. Calcium absorption

    International Nuclear Information System (INIS)

    Carlmark, B.; Reizenstein, P.; Dudley, R.A.

    1976-01-01

    The methods most commonly used to measure the absorption and retention of orally administered calcium are reviewed. Nearly all make use of calcium radioisotopes. The magnitude of calcium absorption and retention depends upon the chemical form and amount of calcium administered, and the clinical and nutritional status of the subject; these influences are briefly surveyed. (author)

  1. The Reaction of Oxy Hemoglobin with Nitrite

    DEFF Research Database (Denmark)

    Hathazi, Denisa; Scurtu, Florina; Bischin, Cristina

    2018-01-01

    The autocatalytic reaction between nitrite and the oxy form of globins involves free radicals. For myoglobin (Mb), an initial binding of nitrite to the iron-coordinated oxygen molecule was proposed; the resulting ferrous-peroxynitrate species was not detected, but its decay product, the high...... to a simple kinetic model involving a transient met-aqua form, in contrast to the ferryl detected in the case of Mb in a similar reaction sequence. These data are in line with a previous observation of a transient accumulation of ferryl Hb under auto-catalytic conditions at much lower concentrations......-peroxynitrate. Density functional theory (DFT) calculations support this latter assignment. The reaction allows for differentiating between the reactivities of various chemically modified hemoglobins, including candidates for blood substitutes. Polymerization of hemoglobin slows the nitrite-induced oxidation, in sharp...

  2. Platelet inhibition by nitrite is dependent on erythrocytes and deoxygenation.

    Directory of Open Access Journals (Sweden)

    Sirada Srihirun

    Full Text Available Nitrite is a nitric oxide (NO metabolite in tissues and blood, which can be converted to NO under hypoxia to facilitate tissue perfusion. Although nitrite is known to cause vasodilation following its reduction to NO, the effect of nitrite on platelet activity remains unclear. In this study, the effect of nitrite and nitrite+erythrocytes, with and without deoxygenation, on platelet activity was investigated.Platelet aggregation was studied in platelet-rich plasma (PRP and PRP+erythrocytes by turbidimetric and impedance aggregometry, respectively. In PRP, DEANONOate inhibited platelet aggregation induced by ADP while nitrite had no effect on platelets. In PRP+erythrocytes, the inhibitory effect of DEANONOate on platelets decreased whereas nitrite at physiologic concentration (0.1 µM inhibited platelet aggregation and ATP release. The effect of nitrite+erythrocytes on platelets was abrogated by C-PTIO (a membrane-impermeable NO scavenger, suggesting an NO-mediated action. Furthermore, deoxygenation enhanced the effect of nitrite as observed from a decrease of P-selectin expression and increase of the cGMP levels in platelets. The ADP-induced platelet aggregation in whole blood showed inverse correlations with the nitrite levels in whole blood and erythrocytes.Nitrite alone at physiological levels has no effect on platelets in plasma. Nitrite in the presence of erythrocytes inhibits platelets through its reduction to NO, which is promoted by deoxygenation. Nitrite may have role in modulating platelet activity in the circulation, especially during hypoxia.

  3. Carbon-Fiber Nitrite Microsensor for In Situ Biofilm Monitoring

    Science.gov (United States)

    During nitrification, nitrite is produced as an intermediate when ammonia is oxidized to nitrate. It is well established that nitrifying biofilm are involved in nitrification episodes in chloraminated drinking water distribution systems with nitrite accumulation occurring during ...

  4. 9 CFR 319.2 - Products and nitrates and nitrites.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Products and nitrates and nitrites... and nitrates and nitrites. Any product, such as frankfurters and corned beef, for which there is a standard in this part and to which nitrate or nitrite is permitted or required to be added, may be prepared...

  5. 40 CFR 721.4740 - Alkali metal nitrites.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkali metal nitrites. 721.4740... Substances § 721.4740 Alkali metal nitrites. (a) Chemical substances and significant new use subject to reporting. (1) The category of chemical substances which are nitrites of the alkali metals (Group IA in the...

  6. SPECTROPHOTOMETRIC DETERMINATION OF NITRITE BY ITS ...

    African Journals Online (AJOL)

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    sources of nitrite include intensive use of chemical nitrogenous fertilizers, ... The current paper describes another kinetic spectrophotometric method for determination of ... s at λmax = 570 nm (allowing a lag time of 5 s) against water as reference. ... samples and the total amount of the analyte was estimated by applying the ...

  7. 21 CFR 172.175 - Sodium nitrite.

    Science.gov (United States)

    2010-04-01

    ... preservative and color fixative, with sodium nitrate, in meat-curing preparations for the home curing of meat and meat products (including poultry and wild game), with directions for use which limit the amount of sodium nitrite to not more than 200 parts per million in the finished meat product, and the amount of...

  8. 21 CFR 573.700 - Sodium nitrite.

    Science.gov (United States)

    2010-04-01

    ..., FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive... as a preservative and color fixative in canned pet food containing fish, meat, and fish and meat... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sodium nitrite. 573.700 Section 573.700 Food and...

  9. Nitrite maxima in the Northern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Sankaranarayanan, V.N.; DeSousa, S.N.; Fondekar, S.P.

    There are 2 nitrite maxima in the Northern Arabian Sea, one at the thermocline depth and the other at depths between 300 and 500 m. The 2nd maximum is more prominent in the northeastern part of the Arabian Sea. The 1st maximum is associated...

  10. Neutralization of wastewater from nitrite passivation

    International Nuclear Information System (INIS)

    Pawlowski, L.; Mientki, B.; Wasag, H.

    1982-01-01

    A method for neutralization of wastewater formed in nitrite passivation has been presented. The method consists of introducing urea into wastewater and acidifying it with sulphuric acid. Wastewater is neutralized with lime. After clarification, wastewater can be drained outside the plant

  11. Calcium - ionized

    Science.gov (United States)

    ... diuretics Thrombocytosis (high platelet count) Tumors Vitamin A excess Vitamin D excess Lower-than-normal levels may be due to: Hypoparathyroidism Malabsorption Osteomalacia Pancreatitis Renal failure Rickets Vitamin D deficiency Alternative Names Free calcium; Ionized calcium ...

  12. Calcium Carbonate

    Science.gov (United States)

    ... Calcium is needed by the body for healthy bones, muscles, nervous system, and heart. Calcium carbonate also ... to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in ...

  13. Modification of membrane sulfhydryl groups in bacteriostatic action of nitrite

    International Nuclear Information System (INIS)

    Buchman, G.W. III; Hansen, J.N.

    1987-01-01

    The mechanism by which nitrite inhibits outgrowing spores of bacillus cereus T was examined by using techniques developed earlier for nitrite analogs. The morphological stage of inhibition, cooperativity effects, effect of pH on inhibition, kinetics of protection against tritiated iodoacetate incorporation into membrane sulfhydryl groups, and protection against the bacteriocidal effect of carboxymethylation of iodoacetate indicate that nitrite acts as a membrane-directed sulfhydryl agent. The mechanism by which nitrite modifies the chemical reactivity of the sulfhyrdyl group could be either direct covalent modification or inactivation through communication with another modified membrane component. Profiles of pH effects suggest that the active agent is the protonated form of nitrite. The nitrite concentrations which modify membrane sulfhydryl activity coincide with those which have a bacteriostatic effect. These results are consistent with membrane sulfhydryl modification as a component of the mechanism of nitrite-induced bacteriostasis in this aerobic sporeformer

  14. Mutagenesis breeding research of Lactobacillus brevis of nitrite reduction

    Directory of Open Access Journals (Sweden)

    LI Zeli

    2015-10-01

    Full Text Available The pollution of nitrite in food became one of the focus of food safety issues,the use of biotechnology methods degrading nitrite became hotspot.The primitive strain was Lactobacillus brevis C2,preserved in our laboratory,had the ability to degrade nitrite,through composite mutagenesis of 15 W,254 nm,20 cm ultraviolet mutagenesis (UV for 120 s and 0.8% diethyl sulfate(DES in 37℃ mutation for 40 min,after screening,we successfully obtained high efficient strain of nitrite degradation,named UV6-DS2,relative to the starting strain,under the condition of 400 mg/L nitrite,after 12 h degradation,nitrite degradation rate increased from 92.8% to 97.8%,to explore its application in food was able to effectively reduce concentration of nitrite in food.

  15. Nitrate decreases xanthine oxidoreductase-mediated nitrite reductase activity and attenuates vascular and blood pressure responses to nitrite.

    Science.gov (United States)

    Damacena-Angelis, Célio; Oliveira-Paula, Gustavo H; Pinheiro, Lucas C; Crevelin, Eduardo J; Portella, Rafael L; Moraes, Luiz Alberto B; Tanus-Santos, Jose E

    2017-08-01

    Nitrite and nitrate restore deficient endogenous nitric oxide (NO) production as they are converted back to NO, and therefore complement the classic enzymatic NO synthesis. Circulating nitrate and nitrite must cross membrane barriers to produce their effects and increased nitrate concentrations may attenuate the nitrite influx into cells, decreasing NO generation from nitrite. Moreover, xanthine oxidoreductase (XOR) mediates NO formation from nitrite and nitrate. However, no study has examined whether nitrate attenuates XOR-mediated NO generation from nitrite. We hypothesized that nitrate attenuates the vascular and blood pressure responses to nitrite either by interfering with nitrite influx into vascular tissue, or by competing with nitrite for XOR, thus inhibiting XOR-mediated NO generation. We used two independent vascular function assays in rats (aortic ring preparations and isolated mesenteric arterial bed perfusion) to examine the effects of sodium nitrate on the concentration-dependent responses to sodium nitrite. Both assays showed that nitrate attenuated the vascular responses to nitrite. Conversely, the aortic responses to the NO donor DETANONOate were not affected by sodium nitrate. Further confirming these results, we found that nitrate attenuated the acute blood pressure lowering effects of increasing doses of nitrite infused intravenously in freely moving rats. The possibility that nitrate could compete with nitrite and decrease nitrite influx into cells was tested by measuring the accumulation of nitrogen-15-labeled nitrite ( 15 N-nitrite) by aortic rings using ultra-performance liquid chromatography tandem mass-spectrometry (UPLC-MS/MS). Nitrate exerted no effect on aortic accumulation of 15 N-nitrite. Next, we used chemiluminescence-based NO detection to examine whether nitrate attenuates XOR-mediated nitrite reductase activity. Nitrate significantly shifted the Michaelis Menten saturation curve to the right, with a 3-fold increase in the

  16. Behaviors of nitrite in cured meat

    International Nuclear Information System (INIS)

    Miwa, Misao

    1980-01-01

    The behaviors of nitrite in cured meat were studied by means of 15 N on the basis of the gaseous 15 N volume from the added nitric acid. The myoglobin, 15 N-nitrite and ascorbate model systems showed a 15 N recovery rate of approximately 100%, but actual meat samples, treated similarly, showed a recovery rate ranging from 66 to 90%, with formation of an unidentified 15 N agent. The largest amount of this unidentified agent was obtained by reaction of the 0.05 M NaCl-soluble dialyzable fraction of meat with 15 N-nitrite. When the reaction product was isolated by Sephadex column chromatography, 15 N in the fraction, which was thought to be the agent, contained approximately 26% of the added 15 N, possessed no UV absorption, and was negative for a ninhydrin reagent. Of the NaCl soluble fraction, reaction in the acidic fraction produced the largest quantity of the unidentified 15 N compound (31% of the added 15 N). This compound was strongly acidic and consisted of 30.7% C, 6.6% H and 4.9% N on element analysis. It showed no mutagenicity against Salmonella by Ames Test. (Chiba, N.)

  17. Nitrite in feed: From Animal health to human health

    Energy Technology Data Exchange (ETDEWEB)

    Cockburn, Andrew [Institute for Research on Environment and Sustainability, Devonshire Building, University of Newcastle upon Tyne, Newcastle upon Tyne, NE17RU (United Kingdom); Brambilla, Gianfranco [Istituto Superiore di Sanità, Toxicological chemistry unit, Viale Regina Elena 299, 00161 Rome (Italy); Fernández, Maria-Luisa [Departamento de Medio Ambiente, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Ministerio de Ciencia e Innovación, Carretera de la Coruña, 28040 Madrid (Spain); Arcella, Davide [Unit on Data Collection and Exposure, European Food Safety Authority, Largo N. Palli 5/A43100 Parma (Italy); Bordajandi, Luisa R. [Unit on Contaminants in the Food chain, European Food Safety Authority, Largo N. Palli 5/A, 43100 Parma (Italy); Cottrill, Bruce [Policy Delivery Group, Animal Health and Welfare, ADAS, Wolverhampton (United Kingdom); Peteghem, Carlos van [University of Gent, Harelbekestraat 72, 9000 Gent (Belgium); Dorne, Jean-Lou, E-mail: jean-lou.dorne@efsa.europa.eu [Unit on Contaminants in the Food chain, European Food Safety Authority, Largo N. Palli 5/A, 43100 Parma (Italy)

    2013-08-01

    Nitrite is widely consumed from the diet by animals and humans. However the largest contribution to exposure results from the in vivo conversion of exogenously derived nitrate to nitrite. Because of its potential to cause to methaemoglobin (MetHb) formation at excessive levels of intake, nitrite is regulated in feed and water as an undesirable substance. Forages and contaminated water have been shown to contain high levels of nitrate and represent the largest contributor to nitrite exposure for food-producing animals. Interspecies differences in sensitivity to nitrite intoxication principally result from physiological and anatomical differences in nitrite handling. In the case of livestock both pigs and cattle are relatively susceptible. With pigs this is due to a combination of low levels of bacterial nitrite reductase and hence potential to reduce nitrite to ammonia as well as reduced capacity to detoxify MetHb back to haemoglobin (Hb) due to intrinsically low levels of MetHb reductase. In cattle the sensitivity is due to the potential for high dietary intake and high levels of rumen conversion of nitrate to nitrite, and an adaptable gut flora which at normal loadings shunts nitrite to ammonia for biosynthesis. However when this escape mechanism gets overloaded, nitrite builds up and can enter the blood stream resulting in methemoglobinemia. Looking at livestock case histories reported in the literature no-observed-effect levels of 3.3 mg/kg body weight (b.w.) per day for nitrite in pigs and cattle were estimated and related to the total daily nitrite intake that would result from complete feed at the EU maximum permissible level. This resulted in margins of safety of 9-fold and 5-fold for pigs and cattle, respectively. Recognising that the bulkiness of animal feed limits their consumption, these margins in conjunction with good agricultural practise were considered satisfactory for the protection of livestock health. A human health risk assessment was also

  18. Nitrite in feed: From Animal health to human health

    International Nuclear Information System (INIS)

    Cockburn, Andrew; Brambilla, Gianfranco; Fernández, Maria-Luisa; Arcella, Davide; Bordajandi, Luisa R.; Cottrill, Bruce; Peteghem, Carlos van; Dorne, Jean-Lou

    2013-01-01

    Nitrite is widely consumed from the diet by animals and humans. However the largest contribution to exposure results from the in vivo conversion of exogenously derived nitrate to nitrite. Because of its potential to cause to methaemoglobin (MetHb) formation at excessive levels of intake, nitrite is regulated in feed and water as an undesirable substance. Forages and contaminated water have been shown to contain high levels of nitrate and represent the largest contributor to nitrite exposure for food-producing animals. Interspecies differences in sensitivity to nitrite intoxication principally result from physiological and anatomical differences in nitrite handling. In the case of livestock both pigs and cattle are relatively susceptible. With pigs this is due to a combination of low levels of bacterial nitrite reductase and hence potential to reduce nitrite to ammonia as well as reduced capacity to detoxify MetHb back to haemoglobin (Hb) due to intrinsically low levels of MetHb reductase. In cattle the sensitivity is due to the potential for high dietary intake and high levels of rumen conversion of nitrate to nitrite, and an adaptable gut flora which at normal loadings shunts nitrite to ammonia for biosynthesis. However when this escape mechanism gets overloaded, nitrite builds up and can enter the blood stream resulting in methemoglobinemia. Looking at livestock case histories reported in the literature no-observed-effect levels of 3.3 mg/kg body weight (b.w.) per day for nitrite in pigs and cattle were estimated and related to the total daily nitrite intake that would result from complete feed at the EU maximum permissible level. This resulted in margins of safety of 9-fold and 5-fold for pigs and cattle, respectively. Recognising that the bulkiness of animal feed limits their consumption, these margins in conjunction with good agricultural practise were considered satisfactory for the protection of livestock health. A human health risk assessment was also

  19. Isolation of nitrite-degrading strains from Douchi and their application to degrade high nitrite in Jiangshui.

    Science.gov (United States)

    Guo, Xing; Liu, Bianfang; Gao, Lina; Zhou, Yuan; Shan, Yuanyuan; Lü, Xin

    2018-06-01

    Excessive nitrite in food is potentially harmful to human health because of its carcinogenic effects caused by nitroso-dervivatives. Douchi, which widely distributed throughout the country, is a traditional solid fermented soybean food with low nitrite content. In this study, bacterias which can degrade nitrite were isolated from Douchi and identified according to 16S rDNA sequence. Acinetobacter guillouiae, Acinetobacter bereziniae, Bacillus subtilis, Bacillus tequilensis, Bacillus amyloliquefaciens, Bacillus licheniformis, Bacillus aryabhattai and Bacillus methylotrophicus were selected. It was shown that all strains have nitrite degradation capability, in which 99.41 % nitrite can be degraded by Bacillus subtilis NDS1. The enzyme activities of these strains were determined at 24 h and 48 h, which corresponded to their nitrite degradation rates. The strains were firstly tried to inoculate in Jiangshui, which is a kind of traditional fermented vegetable in northwest China and often has high nitrite content. It was found that Bacillus subtilis NDS1, Bacillus tequilensis NDS3, Acinetobacter bereziniae NDS4, Bacillus subtilis NDS6, Bacillus subtilis NDS12 can degrade nitrite in Jiangshui more quickly, among which Acinetobacter bereziniae NDS4 degraded almost all nitrite in 48 h while it took 180 h for control. These results indicated that the selected strains have potential to become nitrite degradition agent in food. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  20. Nitrate and nitrite in biology, nutrition and therapeutics

    Science.gov (United States)

    Lundberg, Jon O.; Gladwin, Mark T.; Ahluwalia, Amrita; Benjamin, Nigel; Bryan, Nathan S.; Butler, Anthony; Cabrales, Pedro; Fago, Angela; Feelisch, Martin; Ford, Peter C.; Freeman, Bruce A.; Frenneau, Michael; Friedman, Joel; Kelm, Malte; Kevil, Christopher G.; Kim-Shapiro, Daniel B.; Kozlov, Andrey V.; Lancaster, Jack R.; Lefer, David J.; McColl, Kenneth; McCurry, Kenneth; Patel, Rakesh; Petersson, Joel; Rassaf, Tienush; Reutov, Valentin P.; Richter-Addo, George B.; Schechter, Alan; Shiva, Sruti; Tsuchiya, Koichiro; van Faassen, Ernst E.; Webb, Andrew J.; Zuckerbraun, Brian S.; Zweier, Jay L.; Weitzberg, Eddie

    2014-01-01

    Inorganic nitrate and nitrite from endogenous or dietary sources are metabolized in vivo to nitric oxide (NO) and other bioactive nitrogen oxides. The nitrate-nitrite-NO pathway is emerging as an important mediator of blood flow regulation, cell signaling, energetics and tissue responses to hypoxia. The latest advances in our understanding of the biochemistry, physiology and therapeutics of nitrate, nitrite and NO were discussed during a recent two-day meeting at the Nobel Forum, Karolinska Institutet in Stockholm. PMID:19915529

  1. Methaemoglobinaemia due to amyl nitrite inhalation: a case report.

    Science.gov (United States)

    Machabert, R; Testud, F; Descotes, J

    1994-05-01

    Methaemoglobinaemia is a potential toxic effect of aliphatic nitrites which are increasingly abused by male homosexuals and drug addicts because of marked vasodilating properties ('poppers'). In most instances, severe complications were described following the ingestion of large quantities of amyl, butyl or isobutyl nitrites. A deficiency in NADH-dependent haemoglobin reductase in some patients has been noted. This is the first report of symptomatic methaemoglobinaemia following the inhalation of amyl nitrite.

  2. Calcium waves.

    Science.gov (United States)

    Jaffe, Lionel F

    2008-04-12

    Waves through living systems are best characterized by their speeds at 20 degrees C. These speeds vary from those of calcium action potentials to those of ultraslow ones which move at 1-10 and/or 10-20 nm s(-1). All such waves are known or inferred to be calcium waves. The two classes of calcium waves which include ones with important morphogenetic effects are slow waves that move at 0.2-2 microm s(-1) and ultraslow ones. Both may be propagated by cycles in which the entry of calcium through the plasma membrane induces subsurface contraction. This contraction opens nearby stretch-sensitive calcium channels. Calcium entry through these channels propagates the calcium wave. Many slow waves are seen as waves of indentation. Some are considered to act via cellular peristalsis; for example, those which seem to drive the germ plasm to the vegetal pole of the Xenopus egg. Other good examples of morphogenetic slow waves are ones through fertilizing maize eggs, through developing barnacle eggs and through axolotl embryos during neural induction. Good examples of ultraslow morphogenetic waves are ones during inversion in developing Volvox embryos and across developing Drosophila eye discs. Morphogenetic waves may be best pursued by imaging their calcium with aequorins.

  3. The role of nitrite in nitric oxide homeostasis

    DEFF Research Database (Denmark)

    Jensen, Frank Bo

    2009-01-01

    Nitrite is endogenously produced as an oxidative metabolite of nitric oxide, but it also functions as a NO donor that can be activated by a number of cellular proteins under hypoxic conditions. This article discusses the physiological role of nitrite and nitrite-derived NO in blood flow regulation...... mechanisms. Nitrite reduction to NO provides cytoprotection in tissues during ischemia-reperfusion events by inhibiting mitochondrial respiration and limiting reactive oxygen species. It is argued that the study of hypoxia-tolerant lower vertebrates and diving mammals may help evaluate mechanisms and a full...

  4. Unimolecular Reactions of Nitrites and Nitrates.

    Science.gov (United States)

    1983-04-01

    verified the mechanism as being the one originally proposed by Levy, RONO - RO + NO RO + NO- 1 2*RONO •I kRO + NO-- ROH HHO -Hi k5 :and not by direct...produced by ,’Levy’s mechanism. I1 Emission from CH30, C2H50, and l-C3H70 radicals were observed in the photolysis of these nitrites between...wavelengths of 2000 and 1100 A, by Ohbayashi, Akimoto and Tanaka [78]. Emission was assigned to the (A2A1IX2E) transition of CH30 . Bands of NO were also *i

  5. Comparison of Oxidation Kinetics of Nitrite-Oxidizing Bacteria: Nitrite Availability as a Key Factor in Niche Differentiation

    Science.gov (United States)

    Nowka, Boris; Daims, Holger

    2014-01-01

    Nitrification has an immense impact on nitrogen cycling in natural ecosystems and in wastewater treatment plants. Mathematical models function as tools to capture the complexity of these biological systems, but kinetic parameters especially of nitrite-oxidizing bacteria (NOB) are lacking because of a limited number of pure cultures until recently. In this study, we compared the nitrite oxidation kinetics of six pure cultures and one enrichment culture representing three genera of NOB (Nitrobacter, Nitrospira, Nitrotoga). With half-saturation constants (Km) between 9 and 27 μM nitrite, Nitrospira bacteria are adapted to live under significant substrate limitation. Nitrobacter showed a wide range of lower substrate affinities, with Km values between 49 and 544 μM nitrite. However, the advantage of Nitrobacter emerged under excess nitrite supply, sustaining high maximum specific activities (Vmax) of 64 to 164 μmol nitrite/mg protein/h, contrary to the lower activities of Nitrospira of 18 to 48 μmol nitrite/mg protein/h. The Vmax (26 μmol nitrite/mg protein/h) and Km (58 μM nitrite) of “Candidatus Nitrotoga arctica” measured at a low temperature of 17°C suggest that Nitrotoga can advantageously compete with other NOB, especially in cold habitats. The kinetic parameters determined represent improved basis values for nitrifying models and will support predictions of community structure and nitrification rates in natural and engineered ecosystems. PMID:25398863

  6. Effect of the kinetics of ammonium and nitrite oxidation on nitritation success or failure for different biofilm reactor geometries

    DEFF Research Database (Denmark)

    Lackner, Susanne; Smets, Barth F.

    2012-01-01

    was on the influence of key biokinetic parameters (maximum specific growth rates, oxygen and nitrogen affinity constants of AOB (ammonium oxidizing bacteria) and NOB (nitrite oxidizing bacteria)) and their ratios on nitritation efficiency in these geometries. This exhaustive simulation study revealed that nitritation...... strongly depends on the chosen kinetic parameters of AOB and NOB. The maximum specific growth rates (μmax,AOB and μmax,NOB) had the strongest impact on nitritation efficiency (NE). In comparison, the counter-diffusion geometry yielded more parameter combinations (27.5%) that resulted in high NE than the co...

  7. Nitrate and nitrite in biology, nutrition and therapeutics

    NARCIS (Netherlands)

    Lundberg, J.O.; van Faassen, E.E.H.; Gladwin, M.T.; Ahluwalia, A.; Benjamin, N.

    2009-01-01

    Inorganic nitrate and nitrite from endogenous or dietary sources are metabolized in vivo to nitric oxide (NO) and other bioactive nitrogen oxides. The nitrate-nitrite-NO pathway is emerging as an important mediator of blood flow regulation, cell signaling, energetics and tissue responses to hypoxia.

  8. Amperometric Carbon Fiber Nitrite Microsensor for In Situ Biofilm Monitoring

    Science.gov (United States)

    A highly selective needle type solid state amperometric nitrite microsensor based on direct nitrite oxidation on carbon fiber was developed using a simplified fabrication method. The microsensor’s tip diameter was approximately 7 µm, providing a high spatial resolution of at lea...

  9. Inactivation of Yersinia enterocolitica by nitrite and nitrate in food.

    Science.gov (United States)

    de Giusti, M; de Vito, E

    1992-01-01

    The antimicrobial effects of sodium nitrite and sodium and potassium nitrate against Yersinia enterocolitica were investigated in solution and in treated pork meat. Potassium nitrate and sodium nitrate showed only feeble antimicrobial activity in cultures; no antimicrobial activity was detected with sodium nitrite. Conversely, all three salts displayed apparent antimicrobial activity in pork meat, possibly due to selective effects on competitive flora.

  10. Nitrite as a stimulus for ammonia-starved Nitrosomonas europaea

    NARCIS (Netherlands)

    Laanbroek, H.J.; Bär-Gilissen, M.J.; Hoogveld, H.L.

    2002-01-01

    Ammonia-starved cells of Nitrosomonas europaea are able to preserve a high level of ammonia-oxidizing activity in the absence of ammonium. However, when the nitrite-oxidizing cells that form part of the natural nitrifying community do not keep pace with the ammonia-oxidizing cells, nitrite

  11. NITRITE AND NITRATE DETERMINATIONS IN PLASMA - A CRITICAL-EVALUATION

    NARCIS (Netherlands)

    MOSHAGE, H; KOK, B; HUIZENGA, [No Value; JANSEN, PLM

    Plasma nitrite and nitrate determinations are increasingly being used in clinical chemistry as markers for the activity of nitric oxide synthase and the production of nitric oxide radicals. However, a systematic evaluation of the determination of nitrite and nitrate in plasma has not been performed.

  12. Nitrite and nitrate determinations in plasma: a critical evaluation

    NARCIS (Netherlands)

    Moshage, H.; Kok, B.; Huizenga, J. R.; Jansen, P. L.

    1995-01-01

    Plasma nitrite and nitrate determinations are increasingly being used in clinical chemistry as markers for the activity of nitric oxide synthase and the production of nitric oxide radicals. However, a systematic evaluation of the determination of nitrite and nitrate in plasma has not been performed.

  13. Nitrite enhances liver graft protection against cold ischemia ...

    African Journals Online (AJOL)

    Amani Cherif-Sayadi

    2017-03-30

    Mar 30, 2017 ... cold ischemia reperfusion injury through a NOS ... oxidation and lipid peroxidation remained at low levels in both nitrite-treated groups when ... liver graft preservation [15]. ... nitrite activity is dependent on NO production but .... LiversT rat (n = 6) were flushed and preserved in IGL-1 solution ..... The nitrate-.

  14. Calcium Electroporation

    DEFF Research Database (Denmark)

    Frandsen, Stine Krog; Gibot, Laure; Madi, Moinecha

    2015-01-01

    BACKGROUND: Calcium electroporation describes the use of high voltage electric pulses to introduce supraphysiological calcium concentrations into cells. This promising method is currently in clinical trial as an anti-cancer treatment. One very important issue is the relation between tumor cell kill...... efficacy-and normal cell sensitivity. METHODS: Using a 3D spheroid cell culture model we have tested the effect of calcium electroporation and electrochemotherapy using bleomycin on three different human cancer cell lines: a colorectal adenocarcinoma (HT29), a bladder transitional cell carcinoma (SW780......), and a breast adenocarcinoma (MDA-MB231), as well as on primary normal human dermal fibroblasts (HDF-n). RESULTS: The results showed a clear reduction in spheroid size in all three cancer cell spheroids three days after treatment with respectively calcium electroporation (p

  15. A random-sequential mechanism for nitrite binding and active site reduction in copper-containing nitrite reductase

    NARCIS (Netherlands)

    Wijma, HJ; Jeuken, LJC; Verbeet, MP; Armstrong, FA; Canters, GW

    2006-01-01

    The homotrimeric copper-containing nitrite reductase ( NiR) contains one type-1 and one type-2 copper center per monomer. Electrons enter through the type-1 site and are shuttled to the type-2 site where nitrite is reduced to nitric oxide. To investigate the catalytic mechanism of NiR the effects of

  16. Use of nitrite inhalants ("poppers") among American youth.

    Science.gov (United States)

    Wu, Li-Tzy; Schlenger, William E; Ringwalt, Chris L

    2005-07-01

    We examined the patterns and correlates of nitrite inhalant use among adolescents aged 12 to 17 years. Study data were drawn from the 2000 and 2001 National Household Surveys on Drug Abuse. Logistic regression was used to identify the characteristics associated with nitrite inhalant use. Among adolescents aged 12 to 17 years, 1.5% reported any lifetime use of nitrite inhalants. The prevalence of lifetime nitrite inhalant use increased to 12% and 14% among adolescents who were dependent on alcohol and any drug in the past year, respectively. Many nitrite inhalant users used at least three other types of inhalants (68%) and also met the criteria for alcohol (33%) and drug (35%) abuse or dependence. Increased odds of nitrite inhalant use were associated with residing in nonmetropolitan areas, recent utilization of mental health services, delinquent behaviors, past year alcohol and drug abuse and dependence, and multi-drug use. Adolescents who had used nitrite inhalants at least once in their lifetime tend to engage in delinquent activities and report co-occurring multiple drug abuse and mental health problems in the past year.

  17. A comparison of organic and inorganic nitrates/nitrites.

    Science.gov (United States)

    Omar, Sami A; Artime, Esther; Webb, Andrew J

    2012-05-15

    Although both organic and inorganic nitrates/nitrites mediate their principal effects via nitric oxide, there are many important differences. Inorganic nitrate and nitrite have simple ionic structures and are produced endogenously and are present in the diet, whereas their organic counterparts are far more complex, and, with the exception of ethyl nitrite, are all medicinally synthesised products. These chemical differences underlie the differences in pharmacokinetic properties allowing for different modalities of administration, particularly of organic nitrates, due to the differences in their bioavailability and metabolic profiles. Whilst the enterosalivary circulation is a key pathway for orally ingested inorganic nitrate, preventing an abrupt effect or toxic levels of nitrite and prolonging the effects, this is not used by organic nitrates. The pharmacodynamic differences are even greater; while organic nitrates have potent acute effects causing vasodilation, inorganic nitrite's effects are more subtle and dependent on certain conditions. However, in chronic use, organic nitrates are considerably limited by the development of tolerance and endothelial dysfunction, whereas inorganic nitrate/nitrite may compensate for diminished endothelial function, and tolerance has not been reported. Also, while inorganic nitrate/nitrite has important cytoprotective effects against ischaemia-reperfusion injury, continuous use of organic nitrates may increase injury. While there are concerns that inorganic nitrate/nitrite may induce carcinogenesis, direct evidence of this in humans is lacking. While organic nitrates may continue to dominate the therapeutic arena, this may well change with the increasing recognition of their limitations, and ongoing discovery of beneficial effects and specific advantages of inorganic nitrate/nitrite. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. Nitrates and Nitrites in the Treatment of Ischemic Cardiac Disease

    Science.gov (United States)

    Nossaman, Vaughn E.; Nossaman, Bobby D.; Kadowitz, Philip J.

    2010-01-01

    The organic nitrite, amyl of nitrite, was initially used as a therapeutic agent in the treatment of angina pectoris in 1867, but was replaced over a decade later by the organic nitrate, nitroglycerin (NTG), due to the ease of administration and longer duration of action. The administration of organic nitrate esters, such as NTG, continues to be used in the treatment of angina pectoris and heart failure during the birth of modern pharmacology. The clinical effectiveness is due to vasodilator activity in large veins and arteries through an as yet unidentified method of delivering nitric oxide (NO), or a NO-like compound to vascular smooth muscle cells. The major drawback with NTG administration is the rapid development of tolerance; and with amyl of nitrite, the duration and route of administration. Although amyl of nitrite are no longer used in the treatments of hypertension or ischemic heart disease, the nitrite anion has recently been discovered to possess novel pharmacologic actions such as modulating hypoxic vasodilation and providing cytoprotection in ischemia-reperfusion injury. Although the actions of these two similar chemical classes (nitrites and organic nitrates) have often been considered to be alike, we still do not understand their mechanism of action. However, the recent discovery that the nitrite anion, derived from either sodium nitrite or an intermediate NTG form, may act as a storage form for NO and provides support for investigating the use of these agents in the treatment of ischemic cardiovascular states. We review what is presently known about the use of nitrites and nitrates, the potential uses of these agents, and their mechanisms of action. PMID:20539102

  19. Hypoxia tolerance, nitric oxide, and nitrite: Lessons from extreme animals

    DEFF Research Database (Denmark)

    Fago, Angela; B. Jensen, Frank

    2015-01-01

    survival resides in concerted physiological responses, including strong metabolic depression, protection against oxidative damage and – in air breathing animals - redistribution of blood flow. Each of these responses is known to be tightly regulated by nitric oxide (NO) and during hypoxia by its metabolite...... nitrite. The aim of this review is to highlight recent work illustrating the widespread roles of NO and nitrite in the tolerance to extreme oxygen deprivation, in particular in the red-eared slider turtle and crucian carp, but also in diving marine mammals. The emerging picture underscores the importance...... of NO and nitrite signaling in the adaptive response to hypoxia in vertebrate animals....

  20. Electrochemical oxidation of nitrite on nanodiamond powder electrode

    Energy Technology Data Exchange (ETDEWEB)

    Chen, L.H.; Zang, J.B.; Wang, Y.H.; Bian, L.Y. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China)

    2008-03-10

    Nanodiamond (ND) powder electrodes were fabricated and the electrochemical properties were investigated in the solution containing nitrite in this article. This electrode exhibits substantial catalytic ability toward the oxidation of nitrite anions. The electrochemical oxidation mechanism of nitrite on the ND powder electrode is discussed. The oxidation of NaNO{sub 2} is a two-electron transfer process. The electrode reaction rate constant k is estimated to be 2.013 x 10{sup -4} cm/s and (1 - {alpha})n{sub {alpha}} is 0.1643. The peak current increases linearly with the rising of the concentration of NaNO{sub 2}. (author)

  1. Get Enough Calcium

    Science.gov (United States)

    ... Calcium Print This Topic En español Get Enough Calcium Browse Sections The Basics Overview Foods and Vitamins ... women, don't get enough calcium. How much calcium do I need every day? Women: If you ...

  2. Calcium - urine

    Science.gov (United States)

    ... Female urinary tract Male urinary tract Calcium urine test References Bringhurst FR, Demay MB, Kronenberg HM. Hormones and disorders of mineral metabolism. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology . 13th ed. Philadelphia, PA: Elsevier; ...

  3. Cloning and characterization of a nitrite reductase gene related to ...

    African Journals Online (AJOL)

    STORAGESEVER

    2010-03-01

    Mar 1, 2010 ... Alexander et al., 2005) and heme-type nitrite reductase gene (Smith and ... owing to a genotype-dependent response (Zhang et al.,. 1991; Sakhanokho et al., ..... Improvement of cell culture conditions for rice. Jpn. Agric. Res.

  4. Performance of denitrifying microbial fuel cell with biocathode over nitrite

    Directory of Open Access Journals (Sweden)

    Zhao eHuimin

    2016-03-01

    Full Text Available Microbial fuel cell (MFC with nitrite as an electron acceptor in cathode provided a new technology for nitrogen removal and electricity production simultaneously. The influences of influent nitrite concentration and external resistance on the performance of denitrifying MFC were investigated. The optimal effectiveness were obtained with the maximum total nitrogen (TN removal rate of 54.80±0.01 g m-3 d-1. It would be rather desirable for the TN removal than electricity generation at lower external resistance. Denaturing gradient gel electrophoresis suggested that Proteobacteria was the predominant phylum, accounting for 35.72%. Thiobacillus and Afipia might benefit to nitrite removal. The presence of nitrifying Devosia indicated that nitrite was oxidized to nitrate via a biochemical mechanism in the cathode. Ignavibacterium and Anaerolineaceae was found in the cathode as a heterotrophic bacterium with sodium acetate as substrate, which illustrated that sodium acetate in anode was likely permeated through proton exchange membrane to the cathode .

  5. Differential uptake and metabolism of nitrite in normoxic and hypoxic goldfish

    DEFF Research Database (Denmark)

    Jensen, Frank Bo; Hansen, Marie N.

    2011-01-01

    extracellular and intracellular compartments, revealing nitrosative stress with extensive nitros(yl)ation of thiols, amines and heme groups. The degree of nitrosative stress correlated with nitrite load. Nitrate levels increased in all compartments, reflecting that a significant fraction of the nitrite taken up...... was converted to non-toxic nitrate. The generation of methemoglobin and nitrosylhemoglobin (assessed by spectral deconvolution) was more pronounced during normoxic nitrite exposure than during hypoxic nitrite exposure, in agreement with the higher nitrite load in normoxic fish. However, at any given nitrite......Nitrite is a physiological important nitric oxide donor at low concentrations but becomes toxic at high concentrations, as develops in freshwater fish exposed to environmental nitrite. We hypothesized that nitrite uptake across the gills differs between normoxic and hypoxic fish and that nitrite...

  6. Anoxic sulfide biooxidation using nitrite as electron acceptor

    International Nuclear Information System (INIS)

    Mahmood, Qaisar; Zheng Ping; Cai Jing; Wu Donglei; Hu, Baolan; Li Jinye

    2007-01-01

    Biotechnology can be used to assess the well being of ecosystems, transform pollutants into benign substances, generate biodegradable materials from renewable sources, and develop environmentally safe manufacturing and disposal processes. Simultaneous elimination of sulfide and nitrite from synthetic wastewaters was investigated using a bioreactor. A laboratory scale anoxic sulfide-oxidizing (ASO) reactor was operated for 135 days to evaluate the potential for volumetric loading rates, effect of hydraulic retention time (HRT) and substrate concentration on the process performance. The maximal sulfide and nitrite removal rates were achieved to be 13.82 and 16.311 kg/(m 3 day), respectively, at 0.10 day HRT. The process can endure high sulfide concentrations, as the sulfide removal percentage always remained higher than 88.97% with influent concentration up to 1920 mg/L. Incomplete sulfide oxidation took place due to lower consumed nitrite to sulfide ratios of 0.93. It also tolerated high nitrite concentration up to 2265.25 mg/L. The potential achieved by decreasing HRT at fixed substrate concentration is higher than that by increasing substrate concentration at fixed HRT. The process can bear short HRT of 0.10 day but careful operation is needed. Nitrite conversion was more sensitive to HRT than sulfide conversion when HRT was decreased from 1.50 to 0.08 day. Stoichiometric analyses and results of batch experiments show that major part of sulfide (89-90%) was reduced by nitrite while some autooxidation (10-11%) was resulted from presence of small quantities of dissolved oxygen in the influent wastewater. There was ammonia amassing in considerably high amounts in the bioreactor when the influent nitrite concentration reached above 2265.25 mg/L. High ammonia concentrations (200-550 mg/L) in the bioreactor contributed towards the overall inhibition of the process. Present biotechnology exhibits practical value with a high potential for simultaneous removal of nitrite

  7. Nitrite uptake by nitrogen-depleted wheat seedlings

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, W A; Johnson, R E; Volk, R J

    1974-01-01

    Intact, 14-day-old nitrogen-depleted wheat (Triticum vulgare cv. Blueboy) seedlings were exposed to solutions of 0.5 mM KNO/sub 2/, 0.05 mM CaSO/sub 4/ and 1 mM sodium 2-(N-morpholino)-ethanesulfonate, pH 6.1. Nitrite uptake was determined from depletion of the ambient solution or from incorporation of /sup 15/N in the tissue. An initial nitrite uptake shoulder was followed by a relatively slow uptake rate which subsequently increased to a substantially greater rate. This accelerated phase was maintained through 24 h. Nitrite accumulated to a slight extent in the root tissues during the first few hours but declined to low values when the accelerated rate was fully developed, indicating an increase in nitrite reductase activity paralleling the increase in nitrite uptake capacity. About 50% of the nitrogen absorbed as nitrite was translocated to the shoots by 9 to 12 h. Development of the accelerated nitrite uptake rate was restricted in excised roots, in intact plants kept in darkness, by 400 ..mu..g puromycin ml/sup -1/ and by 1 mM L-ethionine. When puromycin and L-ethionine were added after the accelerated phase had been initiated, their effects were not as detrimental as when they were added at first exposure to KNO/sub 2/. The two inhibitors restricted translocation more than uptake. The data indicate an involvement of protein synthesis and a requirement for movement of a substance from shoots to roots for maximal development of the accelerated nitrite uptake phase. A requirement for protein synthesis in the transport of soluble organic nitrogen from roots to shoots is also suggested.

  8. Influence of irradiation on reaction products of nitrite in foodstuffs

    International Nuclear Information System (INIS)

    Mirna, A.; Rau, G.

    1982-01-01

    Nitro alkanes and nitrolic acids are formed in foods by nitrosation reactions with nitrite. Among TEA-responsive compounds nitrolic acid behave to irradiation similar to N-nitrosamines. Some substances, extracted from spices, especially garlic, are also detectable by GC/TEA-chromatogramms of meat products and of reaction products from spices with nitrite show retention times not always clearly differentiated from those of NDMA, NDEA, NPIP and NPYR, respectively. Additional confirmation of such TEA positive compounds, therefore, is necessary. (orig.) [de

  9. Mitochondria recycle nitrite back to the bioregulator nitric monoxide

    International Nuclear Information System (INIS)

    Nohl, H.; Staniek, K.; Sobhian, B.; Bahrami, S.; Redl, H.; Kozlov, A.V.

    2000-01-01

    Nitric monoxide (NO) exerts a great variety of physiological functions. L-Arginine supplies amino groups which are transformed to NO in various NO-synthase-active isoenzyme complexes. NO-synthesis is stimulated under various conditions increasing the tissue of stable NO-metabolites. The major oxidation product found is nitrite. Elevated nitrite levels were reported to exist in a variety of diseases including HIV, reperfusion injury and hypovolemic shock. Denitrifying bacteria such as Paracoccus denitrificans have a membrane bound set of cytochromes (cyt cd 1 , cyt bc) which were shown to be involved in nitrite reduction activities. Mammalian mitochondria have similar cytochromes which form part of the respiratory chain. Like in bacteria quinols are used as reductants of these types of cytochromes. The observation of one-e - divergence from this redox-couple to external dioxygen made us to study whether this site of the respiratory chain may also recycle nitrite back to its bioactive form NO. Thus, the aim of the present study was therefore to confirm the existence of a reductive pathway which reestablishes the existence of the bioregulator NO from its main metabolite NO 2 - . Our results show that respiring mitochondria readily reduce added nitrite to NO which was made visible by nitrosylation of deoxyhemoglobin. The adduct gives characteristic triplet-ESR-signals. Using inhibitors of the respiratory chain for chemical sequestration of respiratory segments we were able to identify the site where nitrite is reduced. The results confirm the ubiquinone/cyt bc 1 couple as the reductant site where nitrite is recycled. The high affinity of NO to the heme-iron of cytochrome oxidase will result in an impairment of mitochondrial energy-production. ''Nitrite tolerance'' of angina pectoris patients using NO-donors may be explained in that way. (author)

  10. [The method to remove nitrite from tap water by tea].

    Science.gov (United States)

    Lu, M; Chen, L; Xian, H

    1997-03-01

    Drinking water (tap water) is polluted in pipelines by bacteria after long distance transportation. The water contains nitrite (NO2-) which is potentially harmful to human health. The nitrite concentrations range from 0.10 to 2.0 mg/L. Our experiment proved that NO2- could not be removed by boiling, but could be removed by tea. As a natural antioxidant, tea contains several antioxidants, such as ascorbic acid and catechins, which removed NO2- from tap water effectively.

  11. THE SPECTROPHOTOMETRIC DETERMINATION OF NITRITES WITH N,N-DIETHYLANILINE

    Directory of Open Access Journals (Sweden)

    O. S. Pogrebnyak

    2015-11-01

    Full Text Available A new spectrophotometric method for nitrite determination was proposed. The method is based on the measurement of absorbance of the N,N-diethylaniline nitrosation product at 475 nm in the hydrochloric acid medium. The optimum concentrations and the influence of various conditions on the determination sensitivity have been determined. The detection limit (blank + 3s for nitrite is 0.98 mg∙L–1 where sis the standard deviation of blank estimation. The linearity range of the calibration graph was over 1.0–100 mg∙L–1 of  nitrite (sr≤ 0.029, n = 8. The metrological characteristics of the procedure were checked by means of method of additives on the control samples and natural waters. The relative error did not exceed 0.06 for nitrite determination on the control samples. The effect of foreign ions in nitrite determination of 1,0∙10−3 mol∙L–1 has been studied. The proposed procedure is simple  and suitable for nitrite determination in various objects.

  12. Determination of nitrite, nitrate and total nitrogen in vegetable samples

    Directory of Open Access Journals (Sweden)

    Manas Kanti Deb

    2007-04-01

    Full Text Available Yellow diazonium cation formed by reaction of nitrite with 6-amino-1-naphthol-3-sulphonic acid is coupled with β-naphthol in strong alkaline medium to yield a pink coloured azo dye. The azo-dyes shows absorption maximum at 510 nm with molar absorptivity of 2.5 ×104 M-1 cm-1. The dye product obeys Beer's law (correlation coefficient = 0.997, in terms of nitrite concentration, up to 2.7 μg NO2 mL-1. The above colour reaction system has been applied successfully for the determination of nitrite, nitrate and total nitrogen in vegetable samples. Unreduced samples give direct measure for nitrite whilst reduction of samples by copperized-cadmium column gives total nitrogen content and their difference shows nitrate content in the samples. Variety of vegetables have been tested for their N-content (NO2-/NO3-/total-N with % RSD ranging between 1.5 to 2.5 % for nitrite determination. The effects of foreign ions in the determination of the nitrite, nitrate, and total nitrogen have been studied. Statistical comparison of the results with those of reported method shows good agreement and indicates no significant difference in precision.

  13. A Review of Nitrate and Nitrite Toxicity in Foods

    Directory of Open Access Journals (Sweden)

    Mir-Jamal Hosseini

    2016-03-01

    Full Text Available Agricultural advancement and population growth have prompted increases in food supplies, and higher crop yields have been made possible through the application of fertilizers. Large quantities of livestock and poultry on farms, along with the accumulation of biomass and agricultural residues, can cause contamination of ground water resources and other water sanitation concerns in both developing and developed countries. Nitrate is mainly used as a fertilizer in agriculture, and because of its high solubility in water, it can create biological problems in the environment. High usage of nitrite in the food industry as a preservative, flavor enhancer, antioxidant, and color stabilizing agent can cause human exposure to this toxic compound. Nitrite is 10 times as toxic as nitrate in humans. Nitrate is converted to nitrite and nitrosamine compounds in the human stomach, which can lead to bladder cancer. In this review, sources of nitrate and nitrite exposure were investigated. Furthermore, the review evaluates standard levels of nitrate and nitrite in different foods, and acceptable daily doses of these compounds in various countries. Finally, we discuss valid methods of nitrate and nitrite identification and removal in foods.

  14. Mutagenicity of some alkyl nitrites used as recreational drugs

    Energy Technology Data Exchange (ETDEWEB)

    Dunkel, V.C.; Cameron, T.P. (National Institute of Health, Bethesda (USA)); Rogers-Back, A.M.; Lawlor, T.E.; Harbell, J.W. (Microbiological Associates Inc., Rockville, MD (USA))

    1989-01-01

    When the AIDS epidemic was in its earliest stages, and prior to identification of HIV as the etiological factor, the use of volatile nitrites by the male homosexual community to enhance sexual activities appeared to have a significant role in this disease. Preliminary observations indicated that that portion of the male homosexual community which developed Kaposi's sarcoma were also heavy nitrite users. These nitrites had been demonstrated to be mutagenic in bacteria and thus it was postulated that they could be responsible for the appearance of the sarcoma. To evaluate further the genotoxic activity of these chemicals, six nitrites, including those most commonly used by homosexuals for sexual gratification, were selected for testing in the mouse lymphoma TK {plus minus} and Salmonell typhimurium mutagenicity assays. One chemical, n-amyl nitrite, was negative in the mouse lymphoma assay, while the other five chemicals, n-butyl, isobutyl, iso-amyl, sec-butyl, and n-propyl nitrite, were positive. All six compounds were positive in the Salmonella assay. The mutagenic and known toxic effects of these chemicals remain a concern because a large population of teenagers and young adults continue to abuse these substances.

  15. [Nitrates and nitrites in meat products--nitrosamines precursors].

    Science.gov (United States)

    Avasilcăi, Liliana; Cuciureanu, Rodica

    2011-01-01

    To determine the content in nitrates and nitrites and the formation of two nitrosamines (N-nitrosodimethylamine--NDMA, and N-nitrosodiethylaamine--NDEA) in samples of chicken ham, dry Banat salami, dry French salami, traditional Romania sausages, and pork pastrami. Nitrites were determined by spectrophotometry with Peter-Griess reagent, and nitrates by the same method after reduction to nitrites with cadmium powder. High performance liquid chromatography with UV detection was used to determine nitrosamines. The initial concentration of nitrates, nitrites, NDMA and NDEA in the samples ranged as follows: 14.10-60.40 mg NO3/kg, 2.70-26.70 mg NO2/kg, from non-detectable to 0.90 microg NDMA/kg, and from non-detectable to 0.27 microg NDEA/kg, respectively. After 28 days the concentrations were: 3.24-17.1 mg NO3/kg, 0.04 -1.87 mg NO2/kg, 0.8-29 microg NDMA/kg, and 11.6-61.9 microg NDEA/kg, respectively. The decreased nitrate and nitrite and increased NDMA and NDEA concentrations prove that in food products nitrosamines are formed due to residual nitrite during their preservation. The determination of nitrasamines revealed levels much above the admitted maximal concentration for these food products.

  16. Intermediates detected by visible spectroscopy during the reaction of nitrite with deoxyhemoglobin: the effect of nitrite concentration and diphosphoglycerate.

    Science.gov (United States)

    Nagababu, Enika; Ramasamy, Somasundaram; Rifkind, Joseph M

    2007-10-16

    The reaction of nitrite with deoxyhemoglobin (deoxyHb) results in the reduction of nitrite to NO, which binds unreacted deoxyHb forming Fe(II)-nitrosylhemoglobin (Hb(II)NO). The tight binding of NO to deoxyHb is, however, inconsistent with reports implicating this reaction with hypoxic vasodilation. This dilemma is resolved by the demonstration that metastable intermediates are formed in the course of the reaction of nitrite with deoxyHb. The level of intermediates is quantitated by the excess deoxyHb consumed over the concentrations of the final products formed. The dominant intermediate has a spectrum that does not correspond to that of Hb(III)NO formed when NO reacts with methemoglobin (MetHb), but is similar to metHb resulting in the spectroscopic determinations of elevated levels of metHb. It is a delocalized species involving the heme iron, the NO, and perhaps the beta-93 thiol. The putative role for red cell reacted nitrite on vasodilation is associated with reactions involving the intermediate. (1) The intermediate is less stable with a 10-fold excess of nitrite and is not detected with a 100-fold excess of nitrite. This observation is attributed to the reaction of nitrite with the intermediate producing N2O3. (2) The release of NO quantitated by the formation of Hb(II)NO is regulated by changes in the distal heme pocket as shown by the 4.5-fold decrease in the rate constant in the presence of 2,3-diphosphoglycerate. The regulated release of NO or N2O3 as well as the formation of the S-nitroso derivative of hemoglobin, which has also been reported to be formed from the intermediates generated during nitrite reduction, should be associated with any hypoxic vasodilation attributed to the RBC.

  17. Time-dependent depletion of nitrite in pork/beef and chicken meat products and its effect on nitrite intake estimation

    Science.gov (United States)

    Merino, Leonardo; Darnerud, Per Ola; Toldrá, Fidel; Ilbäck, Nils-Gunnar

    2016-01-01

    ABSTRACT The food additive nitrite (E249, E250) is commonly used in meat curing as a food preservation method. Because of potential negative health effects of nitrite, its use is strictly regulated. In an earlier study we have shown that the calculated intake of nitrite in children can exceed the acceptable daily intake (ADI) when conversion from dietary nitrate to nitrite is included. This study examined time-dependent changes in nitrite levels in four Swedish meat products frequently eaten by children: pork/beef sausage, liver paté and two types of chicken sausage, and how the production process, storage and also boiling (e.g., simmering in salted water) and frying affect the initial added nitrite level. The results showed a steep decrease in nitrite level between the point of addition to the product and the first sampling of the product 24 h later. After this time, residual nitrite levels continued to decrease, but much more slowly, until the recommended use-by date. Interestingly, this continuing decrease in nitrite was much smaller in the chicken products than in the pork/beef products. In a pilot study on pork/beef sausage, we found no effects of boiling on residual nitrite levels, but frying decreased nitrite levels by 50%. In scenarios of time-dependent depletion of nitrite using the data obtained for sausages to represent all cured meat products and including conversion from dietary nitrate, calculated nitrite intake in 4-year-old children generally exceeded the ADI. Moreover, the actual intake of nitrite from cured meat is dependent on the type of meat source, with a higher residual nitrite levels in chicken products compared with pork/beef products. This may result in increased nitrite exposure among consumers shifting their consumption pattern of processed meats from red to white meat products. PMID:26743589

  18. Effect of Dry Red Grape Pomace as a Nitrite Substitute on the Microbiological and Physicochemical Properties and Residual Nitrite of Dry-cured Sausage

    Directory of Open Access Journals (Sweden)

    Fatemeh Riazi

    2016-07-01

    Full Text Available Background and Objectives: Sodium nitrite and potassium nitrite have been traditionally used for inhibition of Clostridium botulinum and also as an agent to stabilize the color of meat products; however, usage of these additives at high levels could lead to toxicity and cancer originating from the formation of nitrosamines. Nowadays, application of natural preservatives in order to reduce the nitrite content in meat products is increasing. Thus, we used dry red grape pomace (DRGP as a natural alternative to sodium nitrite. Materials and Methods: The effect of two levels of DRGP (1 and 2% on the proximate composition, microbial counts, pH values and residual nitrite level of the samples formulated with two levels of sodium nitrite (30 and 60 mg/kg, as well as the comparison of these sausages with the blank (nitrite-free  and control (full nitrite added samples on the 1rst, 10th, 20th and 30th days of storage at 3-5 °C were evaluated. Results: The results showed that all chemical compositions were in the ranges reported by other researchers, and nitrite was very effective in preventing the microbial growth. Also about 50 % of the ingoing nitrite could be analyzed in the samples after processing. Moreover, the residual nitrite level declined both during the storage of sausage and after the addition of DRGP. Conclusions: The use of DRGP in combination with nitrite for sausages was more effective in keeping the quality and safety of the refrigerated consumer products as indicated by the lower nitrite levels, microbial count and similar composition as compared to the samples treated with nitrite and without nitrite. Keywords: Dry red grape pomace (DRGP, Sausage, Nitrite, Microbial count

  19. Calcium paradox and calcium entry blockers

    NARCIS (Netherlands)

    Ruigrok, T.J.C.; Slade, A.M.; Nayler, W.G.; Meijler, F.L.

    1984-01-01

    Reperfusion of isolated hearts with calcium-containing solution after a short period of calcium-free perfusion results in irreversible cell damage (calcium paradox). This phenomenon is characterized by an excessive influx of calcium into the cells, the rapid onset of myocardial contracture,

  20. Nitrite reduction mechanism on a Pd surface.

    Science.gov (United States)

    Shin, Hyeyoung; Jung, Sungyoon; Bae, Sungjun; Lee, Woojin; Kim, Hyungjun

    2014-11-04

    Nitrate (NO3-) is one of the most harmful contaminants in the groundwater, and it causes various health problems. Bimetallic catalysts, usually palladium (Pd) coupled with secondary metallic catalyst, are found to properly treat nitrate-containing wastewaters; however, the selectivity toward N2 production over ammonia (NH3) production still requires further improvement. Because the N2 selectivity is determined at the nitrite (NO2-) reduction step on the Pd surface, which occurs after NO3- is decomposed into NO2- on the secondary metallic catalyst, we here performed density functional theory (DFT) calculations and experiments to investigate the NO2- reduction pathway on the Pd surface activated by hydrogen. Based on extensive DFT calculations on the relative energetics among ∼100 possible intermediates, we found that NO2- is easily reduced to NO* on the Pd surface, followed by either sequential hydrogenation steps to yield NH3 or a decomposition step to N* and O* (an adsorbate on Pd is denoted using an asterisk). Based on the calculated high migration barrier of N*, we further discussed that the direct combination of two N* to yield N2 is kinetically less favorable than the combination of a highly mobile H* with N* to yield NH3. Instead, the reduction of NO2- in the vicinity of the N* can yield N2O* that can be preferentially transformed into N2 via diverse reaction pathways. Our DFT results suggest that enhancing the likelihood of N* encountering NO2- in the solution phase before combination with surface H* is important for maximizing the N2 selectivity. This is further supported by our experiments on NO2- reduction by Pd/TiO2, showing that both a decreased H2 flow rate and an increased NO2- concentration increased the N2 selectivity (78.6-93.6% and 57.8-90.9%, respectively).

  1. Sodium nitrite: the "cure" for nitric oxide insufficiency.

    Science.gov (United States)

    Parthasarathy, Deepa K; Bryan, Nathan S

    2012-11-01

    This process of "curing" food is a long practice that dates back thousands of years long before refrigeration or food safety regulations. Today food safety and mass manufacturing are dependent upon safe and effective means to cure and preserve foods including meats. Nitrite remains the most effective curing agent to prevent food spoilage and bacterial contamination. Despite decades of rigorous research on its safety and efficacy as a curing agent, it is still regarded by many as a toxic undesirable food additive. However, research within the biomedical science community has revealed enormous therapeutic benefits of nitrite that is currently being developed as novel therapies for conditions associated with nitric oxide (NO) insufficiency. Much of the same biochemistry that has been understood for decades in the meat industry has been rediscovered in human physiology. This review will highlight the fundamental biochemistry of nitrite in human physiology and highlight the risk benefit evaluation surrounding nitrite in food and meat products. Foods or diets enriched with nitrite can have profound positive health benefits. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. Relation between nitrate and nitrite food habits with lung cancer.

    Science.gov (United States)

    Karimzadeh, Laleh; Koohdani, Fariba; Siassi, Fereydoon; Mahmoudi, Mahmoud; Moslemi, Daryoush; Safari, Farid

    2012-01-01

    Nitrites, a probable human carcinogen, generate reactive nitrogen species that may cause damage to the lung. We evaluated the association between nutritional habits related to nitrite and nitrate intake and risk of lung cancer in Mazandaran, Northern Province of Iran. In this case-control study the two groups were matched for gender and age (+/- 5 years). A semi -quantitative food frequency questionnaire (FFQ) was used to collect dietary data about nutritional habits related to nitrate, nitrite, vitamins E and C intake, from 40 lung cancer cases and 40 control subjects admitted at Mazanaran hospitals. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) for the risk of lung cancer using logistic regression. Mean score of nutritional habits in case group was significantly lower than that in control group (P less than or equal 0.001). We observed a positive association between animal sources of nitrate and nitrite intake (OR = 2.7, 95% CI: 0.13-0.96) and risk of lung cancer. Decreased risk of lung cancer was also observed with fruit intake (OR = 0.26, 95% CI: 1.3-11). Our results indicate a probable association between nutritional habits related to animal sources of nitrate and nitrite intake and the risk of lung cancer that requires to be confirmed by other studies.

  3. Dietary nitrate and nitrite: Benefits, risks, and evolving perceptions.

    Science.gov (United States)

    Bedale, Wendy; Sindelar, Jeffrey J; Milkowski, Andrew L

    2016-10-01

    Consumers have an illogical relationship with nitrite (and its precursor, nitrate) in food. Despite a long history of use, nitrite was nearly banned from use in foods in the 1970s due to health concerns related to the potential for carcinogenic nitrosamine formation. Changes in meat processing methods reduced those potential risks, and nitrite continued to be used in foods. Since then, two opposing movements continue to shape how consumers view dietary nitrate and nitrite. The discovery of the profound physiological importance of nitric oxide led to the realization that dietary nitrate contributes significantly to the nitrogen reservoir for nitric oxide formation. Numerous clinical studies have also demonstrated beneficial effects from dietary nitrate consumption, especially in vascular and metabolic health. However, the latest wave of consumer sentiment against food additives, the clean-label movement, has renewed consumer fear and avoidance of preservatives, including nitrite. Education is necessary but may not be sufficient to resolve this disconnect in consumer perception. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Effect of substrate nature on the electrochemical deposition of calcium-deficient hydroxyapatites

    Science.gov (United States)

    Gualdrón-Reyes, A. F.; Domínguez-Vélez, V.; Morales-Morales, J. A.; Cabanzo, R.; Meléndez, A. M.

    2017-01-01

    Calcium phosphates were obtained by reducing nitrate ions to produce hydroxide ions on TiO2/stainless steel and TiO2/titanium electrodes. TiO2 coatings on metallic substrates were prepared by sol-gel dip-coating method. The morphology of deposits was observed by FESEM. Chemical nature of calcium phosphate deposits was identified by Raman micro-spectroscopy and FESEM/EDS microanalysis. Electrochemical behavior of nitrate and nitrite reduction on stainless steel and titanium electrodes was studied by linear sweep voltammetry. In addition, voltammetric study of the calcium phosphate electrodeposition on both electrodes was performed. From these measurements was selected the potential to form a calcium phosphate. A catalytic current associated to nitrate reduction reaction was obtained for stainless steel electrode, leading to significant deposition of calcium phosphate. Ca/P ratio for both substrates was less than 1.67. The formation of calcium deficient hydroxyapatite was confirmed by Raman spectroscopy.

  5. Effect of substrate nature on the electrochemical deposition of calcium-deficient hydroxyapatites

    International Nuclear Information System (INIS)

    Gualdrón-Reyes, A F; Cabanzo, R; Meléndez, A M; Domínguez-Vélez, V; Morales-Morales, J A

    2017-01-01

    Calcium phosphates were obtained by reducing nitrate ions to produce hydroxide ions on TiO 2 /stainless steel and TiO 2 /titanium electrodes. TiO 2 coatings on metallic substrates were prepared by sol-gel dip-coating method. The morphology of deposits was observed by FESEM. Chemical nature of calcium phosphate deposits was identified by Raman micro-spectroscopy and FESEM/EDS microanalysis. Electrochemical behavior of nitrate and nitrite reduction on stainless steel and titanium electrodes was studied by linear sweep voltammetry. In addition, voltammetric study of the calcium phosphate electrodeposition on both electrodes was performed. From these measurements was selected the potential to form a calcium phosphate. A catalytic current associated to nitrate reduction reaction was obtained for stainless steel electrode, leading to significant deposition of calcium phosphate. Ca/P ratio for both substrates was less than 1.67. The formation of calcium deficient hydroxyapatite was confirmed by Raman spectroscopy. (paper)

  6. Quantifying the sources and sinks of nitrite in the oxygen minimum zone of the Eastern Tropical South Pacific

    Science.gov (United States)

    Ji, Qixing; Widner, Brittany; Jayakumar, Amal; Ward, Bess; Mulholland, Margaret

    2017-04-01

    In coastal upwelling regions, high surface productivity leads to high export and intense remineralization consuming oxygen. This, in combination with slow ventilation, creates oxygen minimum zones (OMZ) in eastern boundary regions of the ocean, such as the one off the Peruvian coast in the Eastern Tropical South Pacific. The OMZ is characterized by a layer of high nitrite concentration coinciding with water column anoxia. Sharp oxygen gradients are located above and below the anoxic layer (upper and lower oxyclines). Thus, the OMZ harbors diverse microbial metabolisms, several of which involve the production and consumption of nitrite. The sources of nitrite are ammonium oxidation and nitrate reduction. The sinks of nitrite include anaerobic ammonium oxidation (anammox), canonical denitrification and nitrite oxidation to nitrate. To quantify the sources and sinks of nitrite in the Peruvian OMZ, incubation experiments with 15N-labeled substrates (ammonium, nitrite and nitrate) were conducted on a research cruise in January 2015. The direct measurements of instantaneous nitrite production and consumption rates were compared with ambient nitrite concentrations to evaluate the turnover rate of nitrite in the OMZ. The distribution of nitrite in the water column showed a two-peak structure. A primary nitrite maximum (up to 0.5 μM) was located in the upper oxycline. A secondary nitrite maximum (up to 10 μM) was found in the anoxic layer. A nitrite concentration minimum occurred at the oxic-anoxic interface just below the upper oxycline. For the sources of nitrite, highest rates of ammonium oxidation and nitrate reduction were detected in the upper oxycline, where both nitrite and oxygen concentrations were low. Lower rates of nitrite production were detected within the layer of secondary nitrite maximum. For the sinks of nitrite, the rates of anammox, denitrification and nitrite oxidation were the highest just below the oxic-anoxic interface. Low nitrite consumption

  7. In-situ nitrite analysis in high level waste tanks

    International Nuclear Information System (INIS)

    O'Rourke, P.E.; Prather, W.S.; Livingston, R.R.

    1992-01-01

    The Savannah River Site produces special nuclear materials used in the defense of the United States. Most of the processes at SRS are primarily chemical separations and purifications. In-situ chemical analyses help improve the safety, efficiency and quality of these operations. One area where in situ fiberoptic spectroscopy can have a great impact is the management of high level radioactive waste. High level radioactive waste at SRS is stored in more than 50 large waste tanks. The waste exists as a slurry of nitrate salts and metal hydroxides at pH's higher than 10. Sodium Nitrite is added to the tanks as a corrosion inhibitor. In-situ fiberoptic probes are being developed to measure the nitrate, nitrite and hydroxide concentrations in both liquid and solid fractions. Nitrite levels can be measured between 0.01M and 1M in a 1mm pathlength optical cell

  8. Reduction of nitrate and nitrite salts under hydrothermal conditions

    International Nuclear Information System (INIS)

    Foy, B.R.; Dell'Orco, P.C.; Wilmanns, E.; McInroy, R.; Ely, J.; Robinson, J.M.; Buelow, S.J.

    1994-01-01

    The feasibility of reducing nitrate/nitrite salts under hydrothermal conditions for the treatment of aqueous mixed wastes stored in the underground tanks at the Department of Energy site at Hanford, Washington was studied. The reduction of nitrate and nitrite salts by reaction with EDTA using a tank waste simulant was examined at temperatures between 623K and 800K and pressures between 0.6 and 1.2 kbar. Continuous flow reactors were used to determine kinetics and products of reactions. All reactions were studied under pressures high enough to produce single phase conditions. The reactions are rapid, go to completion in less than a minute, and produce simple products, such as carbonate, nitrogen, and nitrous oxide gases. The experimental results demonstrate the ability of chemical reactions under hydrothermal conditions to reduce the nitrate and nitrite salts and destroy organic compounds in the waste mixtures

  9. Changes in mutagenicity of protein pyrolyzates by reaction with nitrite.

    Science.gov (United States)

    Yoshida, D; Matsumoto, T

    1978-09-01

    Pyrolyzates of protein and related materials were treated with nitrite under acidic conditions, and the mutagenic activity toward Salmonella tester strains was determined. After treatment with nitrite in acidic solution, casein pyrolyzate, an extract of roasted chicken meat, tobacco-smoke condensate and some aromatic amines showed appreciable decreases in their mutagenic activities toward Salmonella typhimurium TA 98. Aromatic amines in the pyrolyzates may be changed by nitrite treatment to other forms having no or lower mutagenic activity toward Salmonella typhimurium TA 98. The contribution by aromatic amines to the total mutagenic activity of the pyrolyzates was as high as 80% in both casein pyrolyzate and extract of roasted chicken meat and 50% in tobacco-smoke condensate. Pyrolyzates of protein and related materials did not show a decrease in the mutagenic activity toward Salmonella typhimurium TA 100 with the same treatment.

  10. Energetics and kinetics of ferrocyanide and nitrate/nitrite reactions

    International Nuclear Information System (INIS)

    Scheele, R.D.; Burger, L.L.; Sell, R.L.

    1994-01-01

    During the 1950's, radiocesium scavenging at the Hanford site resulted in radioactive waste sludges containing ferrocyanide, nitrate, and nitrite. These waters are a concern since certain mixtures of ferrocyanide and nitrate and/or nitrite are known to explode when heated. The authors have used differential scanning calorimetry, thermogravimetric analysis, isothermal calorimetry and gravimetry, and accelerating rate calorimetry to measure the thermal behavior, the reaction enthalpies, and selected kinetic parameters for reactions between sodium nickel ferrocyanide, the suspected ferrocyanide form in Hanford wastes, and nitrate and/or nitrite. These studies indicate that the oxidation proceeds via multiple steps, the initial reaction begins near 200 degrees C, the initial step has a high activation energy (>200 kJ/mole-K), succeeding reaction steps have activation energies ranging from 90 to 160 kJ/mole-K, and that the oxidation yields about 50% of the theoretical heat of reaction for the most energetic reaction

  11. Nebulization of the acidified sodium nitrite formulation attenuates acute hypoxic pulmonary vasoconstriction

    Directory of Open Access Journals (Sweden)

    Surber Mark W

    2010-06-01

    Full Text Available Abstract Background Generalized hypoxic pulmonary vasoconstriction (HPV occurring during exposure to hypoxia is a detrimental process resulting in an increase in lung vascular resistance. Nebulization of sodium nitrite has been shown to inhibit HPV. The aim of this project was to investigate and compare the effects of nebulization of nitrite and different formulations of acidified sodium nitrite on acute HPV. Methods Ex vivo isolated rabbit lungs perfused with erythrocytes in Krebs-Henseleit buffer (adjusted to 10% hematocrit and in vivo anesthetized catheterized rabbits were challenged with periods of hypoxic ventilation alternating with periods of normoxic ventilation. After baseline hypoxic challenges, vehicle, sodium nitrite or acidified sodium nitrite was delivered via nebulization. In the ex vivo model, pulmonary arterial pressure and nitric oxide concentrations in exhaled gas were monitored. Nitrite and nitrite/nitrate were measured in samples of perfusion buffer. Pulmonary arterial pressure, systemic arterial pressure, cardiac output and blood gases were monitored in the in vivo model. Results In the ex vivo model, nitrite nebulization attenuated HPV and increased nitric oxide concentrations in exhaled gas and nitrite concentrations in the perfusate. The acidified forms of sodium nitrite induced higher levels of nitric oxide in exhaled gas and had longer vasodilating effects compared to nitrite alone. All nitrite formulations increased concentrations of circulating nitrite to the same degree. In the in vivo model, inhaled nitrite inhibited HPV, while pulmonary arterial pressure, cardiac output and blood gases were not affected. All nitrite formulations had similar potency to inhibit HPV. The tested concentration of appeared tolerable. Conclusion Nitrite alone and in acidified forms effectively and similarly attenuates HPV. However, acidified nitrite formulations induce a more pronounced increase in nitric oxide exhalation.

  12. Calcium blood test

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003477.htm Calcium blood test To use the sharing features on this page, please enable JavaScript. The calcium blood test measures the level of calcium in the blood. ...

  13. Calcium source (image)

    Science.gov (United States)

    Getting enough calcium to keep bones from thinning throughout a person's life may be made more difficult if that person has ... as a tendency toward kidney stones, for avoiding calcium-rich food sources. Calcium deficiency also effects the ...

  14. Calcium Pyrophosphate Deposition (CPPD)

    Science.gov (United States)

    ... Patient / Caregiver Diseases & Conditions Calcium Pyrophosphate Deposition (CPPD) Calcium Pyrophosphate Deposition (CPPD) Fast Facts The risk of ... young people, too. Proper diagnosis depends on detecting calcium pyrophosphate crystals in the fluid of an affected ...

  15. Calcium carbonate overdose

    Science.gov (United States)

    Tums overdose; Calcium overdose ... Calcium carbonate can be dangerous in large amounts. ... Products that contain calcium carbonate are certain: Antacids (Tums, Chooz) Mineral supplements Hand lotions Vitamin and mineral supplements Other products may also contain ...

  16. Calcium and bones (image)

    Science.gov (United States)

    Calcium is one of the most important minerals for the growth, maintenance, and reproduction of the human ... body, are continually being re-formed and incorporate calcium into their structure. Calcium is essential for the ...

  17. Calcium hydroxide poisoning

    Science.gov (United States)

    Hydrate - calcium; Lime milk; Slaked lime ... Calcium hydroxide ... These products contain calcium hydroxide: Cement Limewater Many industrial solvents and cleaners (hundreds to thousands of construction products, flooring strippers, brick cleaners, cement ...

  18. Safety and sensory aspects of nitrite alternatives in meat curing

    International Nuclear Information System (INIS)

    Shahidi, F.; Pegg, R.B.

    1991-01-01

    The use of nitrite to cure meats (especially bacon) is viewed as undesirable, because it leads to the formation of carcinogenic nitrosamines. The amount of nitrite (10-40 ppm) associated with the cured colour and flavour is fairly harmless, and it is the larger amount, (100-200 ppm) added to preserve the meat, which is potentially harmful. This article reviews various preservatives which can be used in combination with low concentrations of nitrate. The authors consider that the use of lactate, of alternatively radiation sterilization, offers the best safe alternative to nitrate

  19. Calcium in Urine Test

    Science.gov (United States)

    ... K. Brunner & Suddarth's Handbook of Laboratory and Diagnostic Tests. 2 nd Ed, Kindle. Philadelphia: Wolters Kluwer Health, Lippincott Williams & Wilkins; c2014. Calcium, Serum; Calcium and Phosphates, Urine; ...

  20. Transcellular transport of calcium

    Energy Technology Data Exchange (ETDEWEB)

    Terepka, A R; Coleman, J R; Armbrecht, H J; Gunter, T E

    1976-01-01

    Studies of two calcium transporting epithelia, embryonic chick chorioallantoic membrane and the small intestine of rat and chick, have strongly suggested that the transfer of calcium across a cell involves processes distinctly different from intracellular calcium ion regulation. In the proposed model, transcellular calcium transport is considered as a specialized process developed only by certain cells in those tissues charged with bulk transfer of calcium. The overall effect of the endocytotic mechanism is bulk calcium movement across a cell, protection of mitochondria from exposure to high concentrations of calcium, and the avoidance of wide and potentially toxic fluctuations in cytosol ionic calcium levels. (MFB)

  1. Physiology and interaction of nitrate and nitrite reduction in Staphylococcus carnosus.

    OpenAIRE

    Neubauer, H; Götz, F

    1996-01-01

    Staphylococcus carnosus reduces nitrate to ammonia in two steps. (i) Nitrate was taken up and reduced to nitrite, and nitrite was subsequently excreted. (ii) After depletion of nitrate, the accumulated nitrite was imported and reduced to ammonia, which again accumulated in the medium. The localization, energy gain, and induction of the nitrate and nitrite reductases in S. carnosus were characterized. Nitrate reductase seems to be a membrane-bound enzyme involved in respiratory energy conserva...

  2. The redox interplay between nitrite and nitric oxide: From the gut to the brain

    Directory of Open Access Journals (Sweden)

    Cassilda Pereira

    2013-01-01

    We here discuss the implications of the redox conversion of nitrite to ·NO in the gut, how nitrite-derived ·NO may signal from the digestive to the central nervous system, influencing brain function, as well as a putative ascorbate-driven nitrite/NO pathway occurring in the brain.

  3. Neurotoxicity induced by alkyl nitrites: Impairment in learning/memory and motor coordination.

    Science.gov (United States)

    Cha, Hye Jin; Kim, Yun Ji; Jeon, Seo Young; Kim, Young-Hoon; Shin, Jisoon; Yun, Jaesuk; Han, Kyoungmoon; Park, Hye-Kyung; Kim, Hyung Soo

    2016-04-21

    Although alkyl nitrites are used as recreational drugs, there is only little research data regarding their effects on the central nervous system including their neurotoxicity. This study investigated the neurotoxicity of three representative alkyl nitrites (isobutyl nitrite, isoamyl nitrite, and butyl nitrite), and whether it affected learning/memory function and motor coordination in rodents. Morris water maze test was performed in mice after administrating the mice with varying doses of the substances in two different injection schedules of memory acquisition and memory retention. A rota-rod test was then performed in rats. All tested alkyl nitrites lowered the rodents' capacity for learning and memory, as assessed by both the acquisition and retention tests. The results of the rota-rod test showed that isobutyl nitrite in particular impaired motor coordination in chronically treated rats. The mice chronically injected with isoamyl nitrite also showed impaired function, while butyl nitrite had no significant effect. The results of the water maze test suggest that alkyl nitrites may impair learning and memory. Additionally, isoamyl nitrite affected the rodents' motor coordination ability. Collectively, our findings suggest that alkyl nitrites may induce neurotoxicity, especially on the aspect of learning and memory function. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  4. Nitrite toxicity assessment in Danio rerio and Poecilia reticulata

    Directory of Open Access Journals (Sweden)

    Petra Doleželová

    2011-01-01

    Full Text Available Nitrite is a natural component of the nitrogen cycle in the environment. Although it usually occurs in low concentrations, elevated concentrations caused by effluents or affected nitrification process can lead to serious health deterioration of fish. Two aquarium fish zebrafish (Danio rerio and guppy (Poecilia reticulata are recommended to use as model organisms in toxicity tests. However, their sensitivity to nitrite can differ. The aim of this study was to define acute toxicity of nitrite by the semistatic method according to OECD No. 203 (Fish, Acute toxicity test. The series of 4 acute toxicity tests was performed, with 10 fish of both species used for each concentration and for the control. The 96hLC50 NO2- value for D. rerio and P. reticulata was 242.55 ± 15.79 mg·l-1 and 30.2 ± 8.74 mg·l-1, respectively. We have proved significant difference (p D. rerio and P. reticulata. The results showed different sensitivities to nitrites in tested fish species, which could be related to species-specific branchial chloride uptake mechanism. This is the first study on this fish species.

  5. Intramolecular electron transfer in Pseudomonas aeruginosa cd(1) nitrite reductase

    DEFF Research Database (Denmark)

    Farver, Ole; Brunori, Maurizio; Cutruzzolà, Francesca

    2009-01-01

    ) as the level of reduction increased in both the WT and the His mutant. Equilibrium standard enthalpy and entropy changes and activation parameters of this ET process were determined. We concluded that negative cooperativity is a common feature among the cd(1) nitrite reductases, and we discuss this control...

  6. Ammonia and nitrite oxidation in the Eastern Tropical North Pacific

    Science.gov (United States)

    Peng, Xuefeng; Fuchsman, Clara A.; Jayakumar, Amal; Oleynik, Sergey; Martens-Habbena, Willm; Devol, Allan H.; Ward, Bess B.

    2015-12-01

    Nitrification plays a key role in the marine nitrogen (N) cycle, including in oceanic oxygen minimum zones (OMZs), which are hot spots for denitrification and anaerobic ammonia oxidation (anammox). Recent evidence suggests that nitrification links the source (remineralized organic matter) and sink (denitrification and anammox) of fixed N directly in the steep oxycline in the OMZs. We performed shipboard incubations with 15N tracers to characterize the depth distribution of nitrification in the Eastern Tropical North Pacific (ETNP). Additional experiments were conducted to investigate photoinhibition. Allylthiourea (ATU) was used to distinguish the contribution of archaeal and bacterial ammonia oxidation. The abundance of archaeal and β-proteobacterial ammonia monooxygenase gene subunit A (amoA) was determined by quantitative polymerase chain reaction. The rates of ammonia and nitrite oxidation showed distinct subsurface maxima, with the latter slightly deeper than the former. The ammonia oxidation maximum coincided with the primary nitrite concentration maximum, archaeal amoA gene maximum, and the subsurface nitrous oxide maximum. Negligible rates of ammonia oxidation were found at anoxic depths, where high rates of nitrite oxidation were measured. Archaeal amoA gene abundance was generally 1 to 2 orders of magnitude higher than bacterial amoA gene abundance, and inhibition of ammonia-oxidizing bacteria with 10 μM ATU did not affect ammonia oxidation rates, indicating the dominance of archaea in ammonia oxidation. These results depict highly dynamic activities of ammonia and nitrite oxidation in the oxycline of the ETNP OMZ.

  7. Poppers: epidemiology and clinical management of inhaled nitrite abuse.

    Science.gov (United States)

    Romanelli, Frank; Smith, Kelly M; Thornton, Alice C; Pomeroy, Claire

    2004-01-01

    Commonly referred to as "poppers," inhaled nitrites have a long history of abuse. Poppers are rapid-onset, short-acting potent vasodilators that produce a rush characterized by warm sensations and feelings of dizziness. Poppers sometimes are used to facilitate anal intercourse because of their actions on the anal sphincter. Epidemiologically, the frequent use of nitrites by men who have sex with men has led some experts to implicate these chemicals in the pathogenesis of Kaposi's sarcoma and acquired immunodeficiency syndrome. Controlled clinical trials to examine this potential correlation have not been conducted, and the use of nitrites simply may be a marker for other high-risk behaviors such as unprotected sex. Although regulated in the United States, many nitrite compounds and isomers are sold at various venues including bars, bookstores, and over the Internet. Adverse effects associated with these products vary from mild allergic reactions to life-threatening methemoglobinemia. The potential for drug-drug interactions and a propensity toward unsafe sex also exist. Clinicians should be familiar with the populations most likely to abuse these agents and with the clinical effects and management guidelines for acute ingestions.

  8. Hydrogen ion (Ph), ammonia, dissolved oxygen and nitrite ...

    African Journals Online (AJOL)

    Hydrogen ion (pH), dissolved oxygen, ammonia and nitrite concentrations were studied monthly in two systems (re-circulatory and semi-intensive of 3 m2 sizes) each for six months. The systems were each stocked with 200 g of Clarias gariepinus fingerlings. Results showed that all parameters were within acceptable limits ...

  9. Nitrate, Nitrite, and Ammonium Variability in Drinking Water Distribution Systems.

    Science.gov (United States)

    Schullehner, Jörg; Stayner, Leslie; Hansen, Birgitte

    2017-03-09

    Accurate assessments of exposure to nitrate in drinking water is a crucial part of epidemiological studies investigating long-term adverse human health effects. However, since drinking water nitrate measurements are usually collected for regulatory purposes, assumptions on (1) the intra-distribution system variability and (2) short-term (seasonal) concentration variability have to be made. We assess concentration variability in the distribution system of nitrate, nitrite, and ammonium, and seasonal variability in all Danish public waterworks from 2007 to 2016. Nitrate concentrations at the exit of the waterworks are highly correlated with nitrate concentrations within the distribution net or at the consumers' taps, while nitrite and ammonium concentrations are generally lower within the net compared with the exit of the waterworks due to nitrification. However, nitrification of nitrite and ammonium in the distribution systems only results in a relatively small increase in nitrate concentrations. No seasonal variation for nitrate, nitrite, or ammonium was observed. We conclude that nitrate measurements taken at the exit of the waterworks are suitable to calculate exposures for all consumers connected to that waterworks and that sampling frequencies in the national monitoring programme are sufficient to describe temporal variations in longitudinal studies.

  10. Nitrite and nitroso compounds can serve as specific catalase inhibitors.

    Science.gov (United States)

    Titov, Vladimir Yu; Osipov, Anatoly N

    2017-03-01

    We present evidence that nitrite and nitrosothiols, nitrosoamines and non-heme dinitrosyl iron complexes can reversibly inhibit catalase with equal effectiveness. Catalase activity was evaluated by the permanganatometric and calorimetric assays. This inhibition is not the result of chemical transformations of these compounds to a single inhibitor, as well as it is not the result of NO release from these substances (as NO traps have no effect on the extent of inhibition). It was found that chloride and bromide in concentration above 80 mM and thiocyanate in concentration above 20 μM enhance catalase inhibition by nitrite and the nitroso compounds more than 100 times. The inhibition degree in this case is comparable with that induced by azide. We propose that the direct catalase inhibitor is a positively charged NO-group. This group acquires a positive charge in the active center of enzyme by interaction of nitrite or nitroso compounds with some enzyme groups. Halides and thiocyanate protect the NO + group from hydration and thus increase its inhibition effect. It is probable that a comparatively low chloride concentration in many cells is the main factor to protect catalase from inhibition by nitrite and nitroso compounds.

  11. Control of the ambident reactivity of the nitrite ion

    DEFF Research Database (Denmark)

    Dong, Hai; Rahm, Martin; Thota, Niranjan

    2013-01-01

    of this difference was addressed. The ambident reactivity of the nitrite ion has been found to be the cause of the complex product formation observed, which can be controlled by a neighbouring equatorial ester group. Both N-attack and O-attack occur in the absence of the ester group, whereas O-attack is favoured...

  12. Nitrite oxidizing bacteria for water treatment in coastal aquaculture system

    Science.gov (United States)

    Noorak, S.; Rakkhiaw, S.; Limjirakhajornt, K.; Uppabullung, A.; Keawtawee, T.; Sangnoi, Y.

    2018-04-01

    This research aimed to isolate and characterize nitrite oxidizing bacteria and to study their capability for water quality improvement. Fourteen strains of bacteria with nitrite-oxidizing character were isolated after 21 days of enrichment in Pep-Beef-NOB medium contained NaNO2. Two strains, SF-1 and SF-5, showed highest nitrite removal rate for 42.42% and 37.2%, respectively. These strains were determined an efficiency of open-system wastewater treatment for 14 days. The results showed that control, SF-1 and SF-5 had remove ammonia from day 1 to day 6. At the end of the study, ammonia was removed by the control, SF-1 and SF-5 for 81.27%, 70.1% and 69.82%, respectively. Nitrite concentration was lowest at day 8 with removal rate of 98.73%, 98.3% and 97.24% from control, SF-1 and SF-5, respectively. However, nitrite concentration in control experiment was increased again at day 11 whereas in SF-1 and SF-5 were increased at day 13. Chemical Oxygen Demand (COD) was decreased by 77.78%, 73.50% and 78.63% in the control, SF-1 and SF-5, respectively. Biological Oxygen Demand (BOD) in the control, SF-1 and SF-5 were reduced by 85.92%, 79.53% and 82.09%, respectively. Based on 16S rRNA gene, SF-1 and SF-5 were identified as Bacillus vietnamensis and B. firmus, respectively.

  13. Calcium sensing in exocytosis

    DEFF Research Database (Denmark)

    Gustavsson, Natalia; Wu, Bingbing; Han, Weiping

    2012-01-01

    an increase in intracellular calcium levels. Besides the triggering role, calcium signaling modulates the precise amount and kinetics of vesicle release. Thus, it is a central question to understand the molecular machineries responsible for calcium sensing in exocytosis. Here we provide an overview of our...... current understanding of calcium sensing in neurotransmitter release and hormone secretion....

  14. Calcium fluoride

    International Nuclear Information System (INIS)

    King, C.W.; Nestor, O.H.

    1989-01-01

    A new process for producing large, single, oriented crystals of calcium fluoride (CaF 2 ) has been developed which overcomes the limitations of current growing methods. This process has been reduced to practice and has yielded oriented crystals 17.5 x 17.5 x 5 cm 3 . Currently nearing completion is a system for producing 35 x 35 x 7.5 cm 3 single crystals. A scale up to one-meter-square is considered feasible. This crystal growing process makes possible the fabrication of very large CaF 2 windows. Suitability for very high power lasers, however, requires attention to properties beyond mere size. A process to generate higher purity growth stock (starting material) was also developed. The additional purification of the growth stock contributes to lower bulk absorption, the absence of color centers and increased radiation hardness. Also identified were several specific impurities which correlate with radiation hardness. A correlation was found between color centers induced by laser radiation and ionizing radiation. Other CaF 2 crystal properties such as tensile strength, absorption and laser damage thresholds were studied and are discussed

  15. Effect of Dry Red Grape Pomace as a Nitrite Substitute on the Microbiological and Physicochemical Properties and Residual Nitrite of Dry-cured Sausage

    OpenAIRE

    Fatemeh Riazi; Fariba Zeynali; Ebrahim Hoseini; Homa Behmadi

    2016-01-01

    Background and Objectives: Sodium nitrite and potassium nitrite have been traditionally used for inhibition of Clostridium botulinum and also as an agent to stabilize the color of meat products; however, usage of these additives at high levels could lead to toxicity and cancer originating from the formation of nitrosamines. Nowadays, application of natural preservatives in order to reduce the nitrite content in meat products is increasing. Thus, we used dry red grape pomace (DRGP) as a natura...

  16. Mechanism of anodic oxidation of molybdenum and tungsten in nitrate-nitrite melts

    International Nuclear Information System (INIS)

    Yurkinskij, V.P.; Firsova, E.G.; Morachevskij, A.G.

    1987-01-01

    The mechanism of anode oxidation of tungsten and molybdenum in NaNO 3 -KNO 3 (50 mass %) nitrate-nitrite melts with NaNO 2 -KNO 2 (0.5-50 mass %) addition and in NaNO 2 -KNO 2 (35 mole %) nitrite melt in the 516-580 K temperature range is studied. It is supposed that the process of anode dissloving of the mentioned metals in nitrite melt and nitrate-nitrite mixtures is two-electron. Formation of oxide passivating film is possible under electrolysis on the anode surface, the film is then dissolved in nitrate-nitrite melt with formation of molybdates or tungstates

  17. Retention and leaching of nitrite by municipal solid waste incinerator bottom ash under the landfill circumstance.

    Science.gov (United States)

    Yao, Jun; Kong, Qingna; Zhu, Huayue; Long, Yuyang; Shen, Dongsheng

    2015-01-01

    The retention and leaching of nitrite by municipal solid waste incinerator (MSWI) bottom ash could affect its migration in the landfill. In this study, the effect of the dosage of MSWI bottom ash as well as the variation of the landfill environmental parameters including pH, anions and organic matter on the nitrite retention and leaching behavior was investigated by batch experiments. The highest removal percentage (73.0%) of nitrite was observed when the dosage of MSWI bottom ash was 10 g L(-1) in 2 mg L(-1) nitrite solution. Further increase of the dosage would retard the retention, as the nitrite leaching from MSWI bottom ash was enhanced. The optimum retention of nitrite was observed when the pH was 5.0, while the leaching of nitrite showed a consistent reduction with the increase of pH. Besides, the presence of Cl(-), SO4(2)(-) and acetic acid could enhance the leaching of nitrite and mitigate the retention process. However, the retention of nitrite was enhanced by PO4(3)(-), which was probably due to the formation of the apatite, an active material for the adsorption of the nitrite. These results suggested that MSWI bottom ash could affect the migration of nitrite in the landfill, which was related to the variation of the landfill circumstance. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Optimization of free ammonia concentration for nitrite accumulation in shortcut biological nitrogen removal process.

    Science.gov (United States)

    Chung, Jinwook; Shim, Hojae; Park, Seong-Jun; Kim, Seung-Jin; Bae, Wookeun

    2006-03-01

    A shortcut biological nitrogen removal (SBNR) utilizes the concept of a direct conversion of ammonium to nitrite and then to nitrogen gas. A successful SBNR requires accumulation of nitrite in the system and inhibition of the activity of nitrite oxidizers. A high concentration of free ammonia (FA) inhibits nitrite oxidizers, but unfortunately decreases the ammonium removal rate as well. Therefore, the optimal range of FA concentration is necessary not only to stabilize nitrite accumulation but also to achieve maximum ammonium removal. In order to derive such optimal FA concentrations, the specific substrate utilization rates of ammonium and nitrite oxidizers were measured. The optimal FA concentration range appeared to be 5-10 mg/L for the adapted sludge. The simulated results from the modified inhibition model expressed by FA and ammonium/nitrite concentrations were shown very similar to the experimental results.

  19. Fatal methemoglobinemia caused by liniment solutions containing sodium nitrite.

    Science.gov (United States)

    Saito, T; Takeichi, S; Yukawa, N; Osawa, M

    1996-01-01

    We describe a case of fatal methemoglobinemia (MetHb-emia) resulting from application of liniment solution containing large quantities of sodium nitrite. As a remedial treatment of atopic dermatitis, the liniment solution was applied all over the boy's body. Autopsy findings showed no significant macroscopic or microscopic findings except blood tinted chocolate brown color and chronic atopic dermatitis over the whole surface of the body. Quantitation of the methemoglobin (MetHb) in the blood was performed using spectrophotometer; MetHb concentration of the blood was 76%. Ion chromatographic determination revealed a nitrite concentration of 1 mg/L in the serum. Such a liniment solution is not authorized by the Ministry of Public Welfare.

  20. [Methemoglobinemia due to ingestion of isobutyl nitrite ('poppers')].

    Science.gov (United States)

    Pruijm, M T C; de Meijer, P H E M

    2002-12-07

    Two male students, aged 20 and 21 years, developed central cyanosis shortly after drinking 5 ml of 'poppers' (isobutyl nitrite). They presented with methaemoglobinaemia and were hospitalised. After treatment with oxygen and intravenous fluids they could be discharged in good health the following day. Poppers are alkyl nitrites with vasdilative and oxidizing properties. They are used as party drugs (i.e. inhaled) because of their short-lived euphoric effect. Overdose can result in methaemoglobinaemia: the presence of oxidized haemoglobin which is unable to transport oxygen. Depending on the serum level of methaemoglobin this may result in central cyanosis, unconsciousness, coma and even death. Patients with high methaemoglobin levels should be treated with i.v. methylene blue.

  1. Sorbate-nitrite interactions: acetonitrile oxide as an alkylating agent.

    Science.gov (United States)

    Pérez-Prior, M Teresa; Gómez-Bombarelli, Rafael; González-Pérez, Marina; Manso, José A; García-Santos, M Pilar; Calle, Emilio; Casado, Julio

    2009-07-01

    Because chemical species with DNA-damaging and mutagenic activity are formed in sorbate-nitrite mixtures and because sorbic acid sometimes coexists with nitrite occurring naturally or incorporated as a food additive, the study of sorbate-nitrite interactions is important. Here, the alkylating potential of the products resulting from such interactions was investigated. Drawn were the following conclusions: (i) Acetonitrile oxide (ACNO) is the compound responsible for the alkylating capacity of sorbate-nitrite mixtures; (ii) ACNO alkylates 4-(p-nitrobenzyl)pyridine (NBP), a trap for alkylating agents with nucleophilic characteristics similar to those of DNA bases, forming an adduct (AD; epsilon = 1.4 x 10(4) M(-1) cm(-1); lambda = 519 nm); (iii) the NBP alkylation reaction complies with the rate equation, r = d[AD]/dt = k(alk)(ACNO)[ACNO][NBP]-k(hyd)(AD)[AD], k(alk)(ACNO) being the NBP alkylation rate constant for ACNO and k(hyd)(AD) the rate constant for the adduct hydrolysis reaction; (iv) the small fraction of ACNO forming the adduct with NBP, as well as the small magnitude of the quotient (k(alk) (ACNO)/k(hyd)(ACNO)) as compared with those reported for other alkylating agents, such as some lactones and N-alkyl-N-nitrosoureas, reveals the ACNO effective alkylating capacity to be less significant; (v) the low value of the NBP-ACNO adduct life (defined as the total amount of adduct present along the progression of the NBP alkylation per unit of alkylating agent concentration) points to the high instability of this adduct; and (vi) the obtained results are in accordance with the low carcinogenicity of ACNO.

  2. Intragastric nitrites, nitrosamines, and bacterial overgrowth during cimetidine treatment.

    OpenAIRE

    Stockbrugger, R W; Cotton, P B; Eugenides, N; Bartholomew, B A; Hill, M J; Walters, C L

    1982-01-01

    A six week course of cimetidine (1 g/day) healed peptic ulcers in 20 of 23 patients (14 with duodenal ulcer, nine with gastric ulcer). Reduction of basal acid output by 73% and peak acid output by 36% led to a rise in concentrations of intragastric aerobic bacteria and nitrate-reducing bacteria. While the mean intragastric concentration of nitrate was unchanged by treatment, there were statistically significant rises in nitrite and N-nitrosamine concentrations. The conversion from nitrates to...

  3. Determination of nitrate, nitrite, N- nitrosamines, cyanide and ...

    African Journals Online (AJOL)

    The nitrate, nitrite, N- nitrosamines and ascorbic acid content as well as the levels of cyanide in eight brands of fruit juices and twelve brands of sachet water commonly marketed and consumed in Nigeria were estimated. The mean values of nitrate ranged from 2.29±0.05 to 16.50±1.21 mg/L for the juices and 0.64±0.21 to ...

  4. The negative phonon confinement effect in nanoscopic sodium nitrite

    Czech Academy of Sciences Publication Activity Database

    Koroleva, E.Yu.; Nuzhnyy, Dmitry; Pokorný, Jan; Kamba, Stanislav; Kumzerov, Y. A.; Vakhrushev, S. B.; Petzelt, Jan

    2009-01-01

    Roč. 20, č. 39 (2009), 395706/1-395706/7 ISSN 0957-4484 R&D Projects: GA AV ČR KJB100100704; GA ČR(CZ) GA202/09/0682 Institutional research plan: CEZ:AV0Z10100520 Keywords : nanocomposite * sodium nitrite * infrared * THz * Raman * phonon * effective medium approach Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.137, year: 2009

  5. Nitrate ammonification in mangrove soils: a hidden source of nitrite?

    KAUST Repository

    Balk, Melike; Laverman, Anniet M; Keuskamp, Joost A; Laanbroek, Hendrikus J

    2015-01-01

    Nitrate reduction is considered to be a minor microbial pathway in the oxidation of mangrove-derived organic matter due to a limited supply of nitrate in mangrove soils. At a limited availability of this electron acceptor compared to the supply of degradable carbon, nitrate ammonification is thought to be the preferential pathway of nitrate reduction. Mangrove forest mutually differ in their productivity, which may lead to different available carbon to nitrate ratios in their soil. Hence, nitrate ammonification is expected to be of more importance in high- compared to low-productive forests. The hypothesis was tested in flow-through reactors that contain undisturbed mangrove soils from high-productive Avicennia germinans and Rhizophora mangle forests in Florida and low-productive Avicennia marina forests in Saudi Arabia. Nitrate was undetectable in the soils from both regions. It was assumed that a legacy of nitrate ammonification would be reflected by a higher ammonium production from these soils upon the addition of nitrate. Unexpectedly, the soils from the low-productive forests in Saudi Arabia produced considerably more ammonium than the soils from the high-productive forests in Florida. Hence, other environmental factors than productivity must govern the selection of nitrate ammonification or denitrification. A rather intriguing observation was the 1:1 production of nitrite and ammonium during the consumption of nitrate, more or less independent from sampling region, location, sampling depth, mangrove species and from the absence or presence of additional degradable carbon. This 1:1 ratio points to a coupled production of ammonium and nitrite by one group of nitrate-reducing microorganisms. Such a production of nitrite will be hidden by the presence of active nitrite-reducing microorganisms under the nitrate-limited conditions of most mangrove forest soils.

  6. Nitrate ammonification in mangrove soils: a hidden source of nitrite?

    KAUST Repository

    Balk, Melike

    2015-03-02

    Nitrate reduction is considered to be a minor microbial pathway in the oxidation of mangrove-derived organic matter due to a limited supply of nitrate in mangrove soils. At a limited availability of this electron acceptor compared to the supply of degradable carbon, nitrate ammonification is thought to be the preferential pathway of nitrate reduction. Mangrove forest mutually differ in their productivity, which may lead to different available carbon to nitrate ratios in their soil. Hence, nitrate ammonification is expected to be of more importance in high- compared to low-productive forests. The hypothesis was tested in flow-through reactors that contain undisturbed mangrove soils from high-productive Avicennia germinans and Rhizophora mangle forests in Florida and low-productive Avicennia marina forests in Saudi Arabia. Nitrate was undetectable in the soils from both regions. It was assumed that a legacy of nitrate ammonification would be reflected by a higher ammonium production from these soils upon the addition of nitrate. Unexpectedly, the soils from the low-productive forests in Saudi Arabia produced considerably more ammonium than the soils from the high-productive forests in Florida. Hence, other environmental factors than productivity must govern the selection of nitrate ammonification or denitrification. A rather intriguing observation was the 1:1 production of nitrite and ammonium during the consumption of nitrate, more or less independent from sampling region, location, sampling depth, mangrove species and from the absence or presence of additional degradable carbon. This 1:1 ratio points to a coupled production of ammonium and nitrite by one group of nitrate-reducing microorganisms. Such a production of nitrite will be hidden by the presence of active nitrite-reducing microorganisms under the nitrate-limited conditions of most mangrove forest soils.

  7. Spectrophotometric determination of nitrite in simulated Purex Process solutions

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, I.daC. de; Matsuda, H T; Araujo, B.F. de; Araujo, J.A. de

    1984-01-01

    A spectrophotometric method for nitrite determination in simulated Purex Process solutions is presented, utilizing the Griess reagent for the formation of the coloured azocompound with an absorption maximum at 525 nm. Molar absortivity was 36,262 and the sensitivity of the method 10/sup -6/M for nitrite. The calibration curve is linear in the range of 2 to 30..mu..g NO/sup -//sub 2//25 ml in cells of 1 cm optical path. The method can be used in the presence of uranium up to limits of an U/NO/sup -//sub 2/ ratio of 150. Test solutions were prepared to simulate composition and concentrations as obtained by irradiating standard fuel with a neutro flux of 3.2 x 10/sup 13/ n.s/sup -1/.cm/sup -2/, with a burn-up value of 33,000 Mwd/T and cooling time of two years. Nitrite determinations in these solutions were accurate within limits of 5%.

  8. Influence of turkey meat on residual nitrite in cured meat products.

    Science.gov (United States)

    Kilic, B; Cassens, R G; Borchert, L L

    2001-02-01

    A response surface experimental design was employed to estimate residual nitrite level at various initial nitrite concentrations, percent turkey meat in the formula, and heat quantity (F) values using a typical wiener as the test system. Pork and mechanically separated turkey were used as the meat ingredients. Residual nitrite and pH were measured at day 1, 7 days, 14 days, and 49 days after processing. Protein, fat, salt, moisture, and CIE (L*a*b*) color values were also determined. Results showed that the effect of turkey meat on residual nitrite level was significant (P meat in the formula resulted in lower residual nitrite levels at a fixed pH. The residual nitrite level was initially proportional to initial nitrite concentration, but it became a nonsignificant factor during longer storage time. Differences in heat quantity had a significant effect (P nitrite level initially. Greater heat quantity decreased residual nitrite level in finished cured meat products at a fixed pH. However, this effect became nonsignificant during longer storage. Reduction of residual nitrite in wieners because of turkey meat addition at a fixed pH was due to characteristics of the turkey tissue, but the mechanism of action remains unknown. It was also established that commercial wieners had a higher pH if poultry meat was included in the formulation.

  9. Monitoring nitrite and nitrate residues in frankfurters during processing and storage.

    Science.gov (United States)

    Pérez-Rodríguez, M L; Bosch-Bosch, N; Garciá-Mata, M

    1996-09-01

    Frankfurter-type sausages were prepared in a pilot plant with different concentrations of NaNO(2) (75, 125 or 250 ppm) combined or not with 200 ppm KNO(3). A meat system, free of curing agents, was also used as control. Nitrite and nitrate levels were tested in various processing steps and over 120 days storage at 3 °C of the vacuum-packaged frankfurters. Little influence of the originally added nitrite level on the amount of nitrate formed was observed. Important losses of nitrite and nitrate were due to cooking. Thereafter about 50% of the nitrite added initially remained in this form in all samples (39, 59 and 146 ppm, respectively) and between 10 and 15% as nitrate. When only nitrate was initially added, formation of nitrite after cooking was observed (maximum level 43 ppm NaNO(2)). Formulations prepared with both nitrate and nitrite showed no significant differences (p nitrite or nitrate counterparts. A good correlation among nitrite and nitrate levels and storage time was showed by multiple linear regression analysis. It is concluded that the use of nitrate in combination with nitrite in cooked meat products seems to have little technological significance and adds to the total body burden of nitrite.

  10. The use and control of nitrate and nitrite for the processing of meat products.

    Science.gov (United States)

    Honikel, Karl-Otto

    2008-01-01

    Nitrate and nitrite are used for the purpose of curing meat products. In most countries the use of both substances, usually added as potassium or sodium salts, is limited. Either the ingoing or the residual amounts are regulated by laws. The effective substance is nitrite acting primarily as an inhibitor for some microorganisms. Nitrite added to a batter of meat is partially oxidized to nitrate by sequestering oxygen - thus it acts as an antioxidant - a part of nitrite is bound to myoglobin, forming the heat stable NO-myoglobin, a part is bound to proteins or other substances in meat. Nitrate may be reduced to nitrite in raw meat products by microorganisms. As oxidation and reduction may occur the concentrations of nitrite plus nitrate in a product has to be controlled and measured especially if the residual amounts are regulated. This sum of both compounds is important for the human body. Intake of nitrate with food leads to its absorption over the digestive tract into the blood. In the oral cavity nitrate appears again where it is reduced to nitrite. With the saliva the nitrite is mixed with food, having the same effect as nitrite in a batter (inhibiting growth of some pathogenic microorganisms) and swallowed. In the stomach nitrite can eventually form carcinogenic nitrosamines in the acidic environment.

  11. Changes in plasma and urinary nitrite after birth in premature infants at risk for necrotizing enterocolitis

    Science.gov (United States)

    Pun, Priti; Jones, Jesica; Wolfe, Craig; Deming, Douglas D.; Power, Gordon G.; Blood, Arlin B.

    2016-01-01

    Background Plasma nitrite serves as a reservoir of nitric oxide (NO) bioactivity. Because nitrite ingestion is markedly lower in newborns than adults, we hypothesized plasma nitrite levels would be lower in newborns than in adults, and that infants diagnosed with necrotizing enterocolitis (NEC), a disease characterized by ischemia and bacterial invasion of intestinal walls, would have lower levels of circulating nitrite in the days prior to diagnosis. Methods Single blood and urine samples were collected from 9 term infants and 12 adults, 72 preterm infants every 5 d for 3 wk, and from 13 lambs before and after cord occlusion. Results Nitrite fell 50% relative to cord levels in the first day after birth; and within 15 min after cord occlusion in lambs. Urinary nitrite was higher in infants than adults. Plasma and urinary nitrite levels in infants who developed NEC were similar to those of preterm control infants on days 1 and 5, but significantly elevated at 15 and 20 d after birth. Conclusion Plasma nitrite falls dramatically at birth while newborn urinary nitrite levels are significantly greater than adults. Acute NEC is associated with elevated plasma and urinary nitrite levels. PMID:26539663

  12. Nitrite and nitrate concentrations and metabolism in breast milk, infant formula, and parenteral nutrition.

    Science.gov (United States)

    Jones, Jesica A; Ninnis, Janet R; Hopper, Andrew O; Ibrahim, Yomna; Merritt, T Allen; Wan, Kim-Wah; Power, Gordon G; Blood, Arlin B

    2014-09-01

    Dietary nitrate and nitrite are sources of gastric NO, which modulates blood flow, mucus production, and microbial flora. However, the intake and importance of these anions in infants is largely unknown. Nitrate and nitrite levels were measured in breast milk of mothers of preterm and term infants, infant formulas, and parenteral nutrition. Nitrite metabolism in breast milk was measured after freeze-thawing, at different temperatures, varying oxygen tensions, and after inhibition of potential nitrite-metabolizing enzymes. Nitrite concentrations averaged 0.07 ± 0.01 μM in milk of mothers of preterm infants, less than that of term infants (0.13 ± 0.02 μM) (P milk. Concentrations in parenteral nutrition were equivalent to or lower than those of breast milk. Freeze-thawing decreased nitrite concentration ~64%, falling with a half-life of 32 minutes at 37°C. The disappearance of nitrite was oxygen-dependent and prevented by ferricyanide and 3 inhibitors of lactoperoxidase. Nitrite concentrations in breast milk decrease with storage and freeze-thawing, a decline likely mediated by lactoperoxidase. Compared to adults, infants ingest relatively little nitrite and nitrate, which may be of importance in the modulation of blood flow and the bacterial flora of the infant GI tract, especially given the protective effects of swallowed nitrite. © 2013 American Society for Parenteral and Enteral Nutrition.

  13. Nitrite reductase activity and inhibition of H₂S biogenesis by human cystathionine ß-synthase.

    Directory of Open Access Journals (Sweden)

    Carmen Gherasim

    Full Text Available Nitrite was recognized as a potent vasodilator >130 years and has more recently emerged as an endogenous signaling molecule and modulator of gene expression. Understanding the molecular mechanisms that regulate nitrite metabolism is essential for its use as a potential diagnostic marker as well as therapeutic agent for cardiovascular diseases. In this study, we have identified human cystathionine ß-synthase (CBS as a new player in nitrite reduction with implications for the nitrite-dependent control of H₂S production. This novel activity of CBS exploits the catalytic property of its unusual heme cofactor to reduce nitrite and generate NO. Evidence for the possible physiological relevance of this reaction is provided by the formation of ferrous-nitrosyl (Fe(II-NO CBS in the presence of NADPH, the human diflavin methionine synthase reductase (MSR and nitrite. Formation of Fe(II-NO CBS via its nitrite reductase activity inhibits CBS, providing an avenue for regulating biogenesis of H₂S and cysteine, the limiting reagent for synthesis of glutathione, a major antioxidant. Our results also suggest a possible role for CBS in intracellular NO biogenesis particularly under hypoxic conditions. The participation of a regulatory heme cofactor in CBS in nitrite reduction is unexpected and expands the repertoire of proteins that can liberate NO from the intracellular nitrite pool. Our results reveal a potential molecular mechanism for cross-talk between nitrite, NO and H₂S biology.

  14. Stable-isotope dilution GC-MS approach for nitrite quantification in human whole blood, erythrocytes, and plasma using pentafluorobenzyl bromide derivatization: nitrite distribution in human blood.

    Science.gov (United States)

    Schwarz, Alexandra; Modun, Darko; Heusser, Karsten; Tank, Jens; Gutzki, Frank-Mathias; Mitschke, Anja; Jordan, Jens; Tsikas, Dimitrios

    2011-05-15

    Previously, we reported on the usefulness of pentafluorobenzyl bromide (PFB-Br) for the simultaneous derivatization and quantitative determination of nitrite and nitrate in various biological fluids by GC-MS using their (15)N-labelled analogues as internal standards. As nitrite may be distributed unevenly in plasma and blood cells, its quantification in whole blood rather than in plasma or serum may be the most appropriate approach to determine nitrite concentration in the circulation. So far, GC-MS methods based on PFB-Br derivatization failed to measure nitrite in whole blood and erythrocytes because of rapid nitrite loss by oxidation and other unknown reactions during derivatization. The present article reports optimized and validated procedures for sample preparation and nitrite derivatization which allow for reliable quantification of nitrite in human whole blood and erythrocytes. Essential measures for stabilizing nitrite in these samples include sample cooling (0-4°C), hemoglobin (Hb) removal by precipitation with acetone and short derivatization of the Hb-free supernatant (5 min, 50°C). Potassium ferricyanide (K(3)Fe(CN)(6)) is useful in preventing Hb-caused nitrite loss, however, this chemical is not absolutely required in the present method. Our results show that accurate GC-MS quantification of nitrite as PFB derivative is feasible virtually in every biological matrix with similar accuracy and precision. In EDTA-anticoagulated venous blood of 10 healthy young volunteers, endogenous nitrite concentration was measured to be 486±280 nM in whole blood, 672±496 nM in plasma (C(P)), and 620±350 nM in erythrocytes (C(E)). The C(E)-to-C(P) ratio was 0.993±0.188 indicating almost even distribution of endogenous nitrite between plasma and erythrocytes. By contrast, the major fraction of nitrite added to whole blood remained in plasma. The present GC-MS method is useful to investigate distribution and metabolism of endogenous and exogenous nitrite in blood

  15. Calcium and magnesium determination

    International Nuclear Information System (INIS)

    Bhattacharya, S.K.

    1982-01-01

    The roles of calcium and magnesium in human health and disease have been extensively studied. Calcium and magnesium have been determined in biological specimens by atomic absorption spectroscopy using stiochiometric nitrous oxide-acetylene flame

  16. Fenoprofen calcium overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002649.htm Fenoprofen calcium overdose To use the sharing features on this page, please enable JavaScript. Fenoprofen calcium is a type of medicine called a nonsteroidal ...

  17. Calcium channel blocker overdose

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/002580.htm Calcium-channel blocker overdose To use the sharing features on this page, please enable JavaScript. Calcium-channel blockers are a type of medicine used ...

  18. Calcium and Mitosis

    Science.gov (United States)

    Hepler, P.

    1983-01-01

    Although the mechanism of calcium regulation is not understood, there is evidence that calcium plays a role in mitosis. Experiments conducted show that: (1) the spindle apparatus contains a highly developed membrane system that has many characteristics of sarcoplasmic reticulum of muscle; (2) this membrane system contains calcium; and (3) there are ionic fluxes occurring during mitosis which can be seen by a variety of fluorescence probes. Whether the process of mitosis can be modulated by experimentally modulating calcium is discussed.

  19. Calcium en cardioplegie

    NARCIS (Netherlands)

    Ruigrok, T.J.C.; Meijler, F.L.

    1985-01-01

    Coronary perfusion with a calcium-free solution, followed by reperfusion with a calcium containing solution, may result in acute myocardial cell death and in irreversible loss of the e1ectrical and mechanical activity of the heart. This phenomenon is known as the calcium paradox. A number of

  20. Nitrites and nitrates in the human diet: Carcinogens or beneficial hypotensive agents?

    Science.gov (United States)

    Butler, Anthony

    2015-06-05

    The presence of nitrite in the human diet was thought to constitute a hazard as secondary nitrosamines are known to cause gastric cancers. Recent publications on the physiology of serum nitrite have been consulted. Nitrite is added to some foodstuffs as an antibotulinum agent. The epidemiological evidence that nitrite causes gastric ulcers is weak. On the other hand, evidence that the presence of nitrite in serum lowers blood pressure is strong. This allows us to explain why a Tang dynasty treatment for angina, given in a Dunhuang medical manuscript, can be successful. The presence of nitrite in food is free of danger and a diet high in nitrate is beneficial to the health. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  1. Nitrite and Nitrate Content in Meat Products and Estimated Intake in Denmark From 1998 to 2006

    DEFF Research Database (Denmark)

    Leth, Torben; Fagt, Sisse; Nielsen, S.

    2008-01-01

    The content of nitrite and nitrate in cured meat products has been monitored in Denmark seven times between 1995 and 2006. The maximum permitted added amounts of sodium nitrite in Denmark (60 mg kg(-1) for most products up to 150 mg kg(-1) for special products) have not been exceeded, except...... period with levels varying between 6 and 20 mg sodium nitrite kg(-1) with sausages, meat for open sandwiches and salami-type sausages being the greatest contributors. The mean intake of sodium nitrate was around 1 mg day(-1), which is very low compared with the total intake of 61 mg day(-1). The mean...... group, only very few persons were responsible for the high intake. The conversion of nitrate to nitrite in the saliva and the degradation of nitrite during production and storage must also be considered when evaluating the intake of nitrite....

  2. Nitrite survival and nitrous oxide production of denitrifying phosphorus removal sludges in long-term nitrite/nitrate-fed sequencing batch reactors.

    Science.gov (United States)

    Wang, Yayi; Zhou, Shuai; Ye, Liu; Wang, Hong; Stephenson, Tom; Jiang, Xuxin

    2014-12-15

    Nitrite-based phosphorus (P) removal could be useful for innovative biological P removal systems where energy and carbon savings are a priority. However, using nitrite for denitrification may cause nitrous oxide (N2O) accumulation and emissions. A denitrifying nitrite-fed P removal system [Formula: see text] was successfully set up in a sequencing batch reactor (SBR) and was run for 210 days. The maximum pulse addition of nitrite to [Formula: see text] was 11 mg NO2(-)-N/L in the bulk, and a total of 34 mg NO2(-)-N/L of nitrite was added over three additions. Fluorescent in situ hybridization results indicated that the P-accumulating organisms (PAOs) abundance was 75 ± 1.1% in [Formula: see text] , approximately 13.6% higher than that in a parallel P removal SBR using nitrate [Formula: see text] . Type II Accumulibacter (PAOII) (unable to use nitrate as an electron acceptor) was the main PAOs species in [Formula: see text] , contributing 72% to total PAOs. Compared with [Formula: see text] , [Formula: see text] biomass had enhanced nitrite/free nitrous acid (FNA) endurance, as demonstrated by its higher nitrite denitrification and P uptake rates. N2O accumulated temporarily in [Formula: see text] after each pulse of nitrite. Peak N2O concentrations in the bulk for [Formula: see text] were generally 6-11 times higher than that in [Formula: see text] ; these accumulations were rapidly denitrified to nitrogen gases. N2O concentration increased rapidly in nitrate-cultivated biomass when 5 or 10 mg NO2(-)-N/L per pulse was added. Whereas, N2O accumulation did not occur in nitrite-cultivated biomass until up to 30 mg NO2(-)-N/L per pulse was added. Long-term acclimation to nitrite and pulse addition of nitrite in [Formula: see text] reduced the risk of nitrite accumulation, and mitigated N2O accumulation and emissions from denitrifying P removal by nitrite. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Nitrate reduction to nitrite, nitric oxide and ammonia by gut bacteria under physiological conditions.

    Directory of Open Access Journals (Sweden)

    Mauro Tiso

    Full Text Available The biological nitrogen cycle involves step-wise reduction of nitrogen oxides to ammonium salts and oxidation of ammonia back to nitrites and nitrates by plants and bacteria. Neither process has been thought to have relevance to mammalian physiology; however in recent years the salivary bacterial reduction of nitrate to nitrite has been recognized as an important metabolic conversion in humans. Several enteric bacteria have also shown the ability of catalytic reduction of nitrate to ammonia via nitrite during dissimilatory respiration; however, the importance of this pathway in bacterial species colonizing the human intestine has been little studied. We measured nitrite, nitric oxide (NO and ammonia formation in cultures of Escherichia coli, Lactobacillus and Bifidobacterium species grown at different sodium nitrate concentrations and oxygen levels. We found that the presence of 5 mM nitrate provided a growth benefit and induced both nitrite and ammonia generation in E.coli and L.plantarum bacteria grown at oxygen concentrations compatible with the content in the gastrointestinal tract. Nitrite and ammonia accumulated in the growth medium when at least 2.5 mM nitrate was present. Time-course curves suggest that nitrate is first converted to nitrite and subsequently to ammonia. Strains of L.rhamnosus, L.acidophilus and B.longum infantis grown with nitrate produced minor changes in nitrite or ammonia levels in the cultures. However, when supplied with exogenous nitrite, NO gas was readily produced independently of added nitrate. Bacterial production of lactic acid causes medium acidification that in turn generates NO by non-enzymatic nitrite reduction. In contrast, nitrite was converted to NO by E.coli cultures even at neutral pH. We suggest that the bacterial nitrate reduction to ammonia, as well as the related NO formation in the gut, could be an important aspect of the overall mammalian nitrate/nitrite/NO metabolism and is yet another way in

  4. Enhancing nitrite inhibition of Clostridium botulinum with isoascorbate in perishable canned cured meat.

    Science.gov (United States)

    Tompkin, R B; Christiansen, L N; Shaparis, A B

    1978-01-01

    Addition of sodium isoascorbate to the formulation for perishable canned comminuted cured meat markedly enhanced the efficacy of nitrite against Clostridium botulinum. This effect was reproducible through a series of three tests. In one test it was found that the initial addition of 50 microgram of sodium nitrite per g plus isoascorbate was as effective as 156 microgram of sodium nitrite per g alone. PMID:341810

  5. Modelling nitrite dynamics and associated feedback processes in the Benguela oxygen minimum zone

    Science.gov (United States)

    Mashifane, T. B.; Vichi, M.; Waldron, H. N.; Machu, E.; Garçonc, V.

    2016-08-01

    Understanding nitrite dynamics in oxygen minimum zones (OMZs) is a challenge as it represents an intermediary nitrogen species with a short turnover time. Nitrite is also reduced to nitrogen in OMZs, preventing its accumulation. This creates difficulties in detecting nitrite with colorimetric methods as concentrations may occur below detection limits in some regions. Nitrite concentrations are key to understanding intermediate nitrogen processes and their implication for nitrogen loss in OMZs. A coupled physical-biogeochemical model is applied in the Benguela OMZ to study nitrite dynamics and its associated feedback processes. Simulated results show occurrence of primary and secondary nitrite maxima in the Benguela shelf waters. The primary nitrite maxima in the Benguela are attributed to nitrification and nitrate assimilation as they occur in association with the nitracline. Secondary nitrite maxima accumulate in the Angola-Benguela Front (ABF) OMZ and are attributed to denitrification. The secondary nitrite maxima are consumed by anaerobic ammonium oxidation (anammox) off Walvis Bay. Nitrite maxima are restricted to the shelf off Walvis Bay and advected offshore in the ABF region. Interchanges between the poleward South Atlantic Central Water (SACW) and the equatorward, well-aerated Eastern South Atlantic Central Water (ESACW) drive the seasonality of nitrogen processes in the Benguela. Subsequent nitrite reduction in the Benguela OMZ leads to nitrous oxide production, with high concentrations occurring in the ABF region as a result of nitrification and denitrification. Off Walvis Bay, nitrous oxide production is low since nitrite is consumed by anammox. Nitrous oxide production occurs in thermocline, intermediate and deeper water masses in the ABF region. High N fluxes in the Benguela are attributed to nitrification as compared to anammox and denitrification. Results from this study demonstrate the role of intermediate nitrogen species in nitrogen feedback

  6. Residual Nitrite in Some Egyptian Meat Products and the Reduction Effect of Electron Beam Irradiation

    OpenAIRE

    Dalia A. Zahran; Gehan M.A. Kassem

    2011-01-01

    Nitrite, a curing agent of meat products, is a precursor of carcinogenic N-nitrosamines during processing of meat products or under human stomach conditions, as well as having its own toxicity. To investigate the residual nitrite level in meat products marketed in Egyptian markets, 160 samples of cured cooked (luncheon and frankfurter) and cured raw (oriental sausages and pastirma) meat products (40 sample each) were analyzed for residual nitrite by a spectrophotometric method. Samples were s...

  7. Nitrate Reduction to Nitrite, Nitric Oxide and Ammonia by Gut Bacteria under Physiological Conditions

    Science.gov (United States)

    Tiso, Mauro; Schechter, Alan N.

    2015-01-01

    The biological nitrogen cycle involves step-wise reduction of nitrogen oxides to ammonium salts and oxidation of ammonia back to nitrites and nitrates by plants and bacteria. Neither process has been thought to have relevance to mammalian physiology; however in recent years the salivary bacterial reduction of nitrate to nitrite has been recognized as an important metabolic conversion in humans. Several enteric bacteria have also shown the ability of catalytic reduction of nitrate to ammonia via nitrite during dissimilatory respiration; however, the importance of this pathway in bacterial species colonizing the human intestine has been little studied. We measured nitrite, nitric oxide (NO) and ammonia formation in cultures of Escherichia coli, Lactobacillus and Bifidobacterium species grown at different sodium nitrate concentrations and oxygen levels. We found that the presence of 5 mM nitrate provided a growth benefit and induced both nitrite and ammonia generation in E.coli and L.plantarum bacteria grown at oxygen concentrations compatible with the content in the gastrointestinal tract. Nitrite and ammonia accumulated in the growth medium when at least 2.5 mM nitrate was present. Time-course curves suggest that nitrate is first converted to nitrite and subsequently to ammonia. Strains of L.rhamnosus, L.acidophilus and B.longum infantis grown with nitrate produced minor changes in nitrite or ammonia levels in the cultures. However, when supplied with exogenous nitrite, NO gas was readily produced independently of added nitrate. Bacterial production of lactic acid causes medium acidification that in turn generates NO by non-enzymatic nitrite reduction. In contrast, nitrite was converted to NO by E.coli cultures even at neutral pH. We suggest that the bacterial nitrate reduction to ammonia, as well as the related NO formation in the gut, could be an important aspect of the overall mammalian nitrate/nitrite/NO metabolism and is yet another way in which the microbiome

  8. Nitrogen removal and electricity production at a double-chamber microbial fuel cell with cathode nitrite denitrification.

    Science.gov (United States)

    Yu, Yangyang; Zhao, Jianqiang; Wang, Sha; Zhao, Huimin; Ding, Xiaoqian; Gao, Kun

    2017-12-01

    Double-chamber microbial fuel cell was applied to investigate the performance of the electricity production and nitrite denitrification through feeding nitrite into the cathode. Factors influencing denitrification performance and power production, such as external resistance, influent nitrite concentration and Nitrite Oxygen Bacteria inhibitors, were studied. The results show that when the concentration of nitrite nitrogen and external resistance were 100 mg L -1 and 10 Ω, respectively, the nitrite denitrification reached the best state. The NaN 3 can inhibit nitrite oxidation effectively; meanwhile, the nitrite denitrification with N 2 O as the final products was largely improved. The [Formula: see text] was reduced to [Formula: see text], causing the cathode denitrification coulombic efficiency to exceed 100%. In chemoautotrophic bio-nitrification, microorganisms may utilize H 2 O to oxidize nitrite under anaerobic conditions. Proteobacteria might play a major role in the process of denitrification in MFC.

  9. Determination of Nitrite in Whole Blood by High-Performance Liquid Chromatography with Electrochemical Detection and a Case of Nitrite Poisoning.

    Science.gov (United States)

    Yan, Hui; Zhuo, Xiangyi; Shen, Baohua; Xiang, Ping; Shen, Min

    2016-01-01

    Although nitrite is widely used in meat processing, it is a major toxicity hazard to children and is responsible for the blue-baby syndrome. A simple and effective method to determine nitrite in whole blood has been devised using ion chromatography with suppressed conductivity detection. The blood sample was deproteinized by adding acetonitrile and purified with mini-cartridges to remove hydrophobic compounds, chloride ions, and metal ions. An aliquot of the filtrate was injected onto the ion chromatography. The retention time for nitrite was 13.8 min and the detection limit of nitrite in whole blood was 0.4 μmol/L. The calibration curve was linear (r(2) = 0.9999) over the concentration working range. The blood nitrite concentration of a victim who attempted suicide by ingesting sodium nitrite powder was determined using the present method. The basal levels for nitrite in human blood was determined with 7.1 ± 0.9 μmol/L (n = 12). © 2015 American Academy of Forensic Sciences.

  10. Radiation preservation with reduced nitrites of bacon and other cured meats - a review

    International Nuclear Information System (INIS)

    Singh, H.

    1987-01-01

    The main problem caused by nitrite as a preservative is the formation of carcinogenic nitrosamines in bacon and other cured meats. This has led to a search for alternatives to the use of nitrite. Irradiation with reduced level of nitrite is a promising alternative to the use of current levels of nitrite. Radurization (radiation pasteurization) of bacon containing 20 to to 40 mg/kg of nitrite in evacuated packages, irradiated and stored at 4 degrees C, gives a product with good organoleptic qualities and extended shelf life of > 80 days vs. < days 30 days for the conventionally treated bacon. Radappertization (radiation sterilization) of bacon containing 20 mg/kg of nitrite at a dose of about 30 kGy, irradiated at -20 degrees or lower in evacuated packages, results in a product that is shelf stable for months to years at room temperature (∼ 25 degrees C). It has organoleptic properties comparable to commercial bacon in terms of color, flavor, odor and texture. Irradiation also reduces the nitrite and preformed nitrosamines present in bacon. Lower levels of nitrosamines are formed on cooking irradiated bacon containing presently used commercial levels of nitrite (120-150 mg/kg) and the levels of nitrosamines become negligible with 20 mg/kg of nitrite. Various aspects of preservation of bacon and other cured meats are reviewed in this report with emphasis on radiation processing. 357 refs

  11. Total salivary nitrates and nitrites in oral health and periodontal disease.

    Science.gov (United States)

    Sánchez, Gabriel A; Miozza, Valeria A; Delgado, Alejandra; Busch, Lucila

    2014-01-30

    It is well known that nitrites are increased in saliva from patients with periodontal disease. In the oral cavity, nitrites may derive partly from the reduction of nitrates by oral bacteria. Nitrates have been reported as a defence-related mechanism. Thus, the aim of the present study was to determine the salivary levels of total nitrate and nitrite and their relationship, in unstimulated and stimulated saliva from periodontal healthy subjects, and from patients with chronic periodontal disease. Nitrates and nitrites were determined in saliva from thirty healthy subjects and forty-four patients with periodontal disease. A significant increase in salivary nitrates and nitrites was observed. Nitrates and nitrites concentration was related to clinical attachment level (CAL). A positive and significant Pearson's correlation was found between salivary total nitrates and nitrites. Periodontal treatment induced clinical improvement and decreased nitrates and nitrites. It is concluded that salivary nitrates and nitrites increase, in patients with periodontal disease, could be related to defence mechanisms. The possibility that the salivary glands respond to oral infectious diseases by increasing nitrate secretion should be explored further. Copyright © 2013 Elsevier Inc. All rights reserved.

  12. Low nitrous oxide production in intermittent-feed high performance nitritating reactors

    DEFF Research Database (Denmark)

    Su, Qingxian; Jensen, Malene M.; Smets, Barth F.

    Nitrous oxide (N2O) production from autotrophic nitrogen removal processes, especially nitritating systems, is of growing concern. N2O dynamics were characterized and N2O production factors were quantified in two lab-scale intermittent-feed nitritating SBRs. 93 ± 14% of the oxidized ammonium...... was converted to nitrite, with the average total net N2O production of 2.1 ± 0.7% of the ammonium oxidized. Operation with intermittent feeding appears an effective optimization approach to mitigate N2O emissions from nitritating systems. Net N2O production rates transiently increased with a rise in pH after...

  13. Color Developing Capacity of Plasma-treated Water as a Source of Nitrite for Meat Curing.

    Science.gov (United States)

    Jung, Samooel; Kim, Hyun Joo; Park, Sanghoo; Yong, Hae In; Choe, Jun Ho; Jeon, Hee-Joon; Choe, Wonho; Jo, Cheorun

    2015-01-01

    The interaction of plasma with liquid generates nitrogen species including nitrite (NO(-) 2). Therefore, the color developing capacity of plasma-treated water (PTW) as a nitrite source for meat curing was investigated in this study. PTW, which is generated by surface dielectric barrier discharge in air, and the increase of plasma treatment time resulted in increase of nitrite concentration in PTW. The PTW used in this study contains 46 ppm nitrite after plasma treatment for 30 min. To evaluate the effect of PTW on the cured meat color, meat batters were prepared under three different conditions (control, non-cured meat batter; PTW, meat batter cured with PTW; Sodium nitrite, meat batter cured with sodium nitrite). The meat batters were vacuum-packaged and cooked in a water-bath at 80℃ for 30 min. The typical color of cured meat developed in cooked meat batter treated with sodium nitrite or PTW. The lightness (L*) and yellowness (b*) values were similar in all conditions, whereas, the redness (a*) values of cooked meat batter with PTW and sodium nitrite (pnitrite source in the curing process of meat without addition of other nitrite sources.

  14. Can urinary nitrite results be used to conduct antimicrobial option for urinary tract infection in children?

    Science.gov (United States)

    Mahyar, Abolfazl; Ayazi, Parviz; Froozesh, Mahta; Daneshi-Kohan, Mohammad-Mahdi; Barikani, Ameneh

    2012-06-01

    This study was performed to determine the relationship between urinary nitrite results and bacterial resistance to antimicrobial drugs in urinary tract infection of children. In a cross-section study 119 children younger than 12 years with urinary tract infection were evaluated in Qazvin children's hospital. Patients were divided into negative and positive nitrite groups depending on urinary nitrite test result. Rates of antibiotic resistance in the two groups were compared. Sixty seven patients were in the negative nitrite group and 52 in the positive nitrite group. Resistance rates to ceftriaxone, trimethoprim sulfamethoxazole, ampicillin, gentamicin, amikacin, nalidixic acid, cephalothin and nitrofurantoin in the nitrite negative group were 7.5%, 31.3%, 50.7%, 11.9%, 9%, 3%, 14.9% and 11.9%, respectively. These values in the nitrite positive group were 21.2%, 28.8%, 63.5%, 7.7%, 5.8%, 1.9%, 9.6%, and 3.8%, respectively (P>0.05). This study showed that there is no correlation between urinary nitrite results and bacterial resistance to antimicrobial drugs. Therefore, it seems that physicians should not adjust antibiotic therapy for UTI based on nitrite results.

  15. Effect of Nitrite Inhibitor on the Macrocell Corrosion Behavior of Reinforcing Steel

    Directory of Open Access Journals (Sweden)

    Zhonglu Cao

    2015-01-01

    Full Text Available The effect of nitrite ions on the macrocell corrosion behavior of reinforcing steel embedded in cement mortar was investigated by comparing and analyzing the macrocell corrosion current, macrocell polarization ratios, and slopes of anodic and cathodic steels. Based on the experimental results, the relationship between macrocell potential difference and macrocell current density was analyzed, and the mechanism of macrocell corrosion affected by nitrite ions was proposed. The results indicated that nitrite ions had significant impact on the macrocell polarization ratios of cathode and anode. The presence of nitrite could reduce the macrocell current by decreasing the macrocell potential difference and increasing the macrocell polarization resistance of the anode.

  16. Interactions of nitrite with catalase: Enzyme activity and reaction kinetics studies.

    Science.gov (United States)

    Krych-Madej, Justyna; Gebicka, Lidia

    2017-06-01

    Catalase, a heme enzyme, which catalyzes decomposition of hydrogen peroxide to water and molecular oxygen, is one of the main enzymes of the antioxidant defense system of the cell. Nitrite, used as a food preservative has long been regarded as a harmful compound due to its ability to form carcinogenic nitrosamines. Recently, much evidence has been presented that nitrite plays a protective role as a nitric oxide donor under hypoxic conditions. In this work the effect of nitrite on the catalytic reactions of catalase was studied. Catalase was inhibited by nitrite, and this process was pH-dependent. IC 50 values varied from about 1μM at pH5.0 to about 150μM of nitrite at pH7.4. The presence of chloride significantly enhanced nitrite-induced catalase inhibition, in agreement with earlier observations. The kinetics of the reactions of nitrite with ferric catalase, its redox intermediate, Compound I, and catalase inactive form, Compound II, was also studied. Possible mechanisms of nitrite-induced catalase inhibition are analyzed and the biological consequences of the reactions of catalase with nitrite are discussed. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Microbial competition among anammox bacteria in nitrite-limited bioreactors

    KAUST Repository

    Zhang, Lei; Narita, Yuko; Gao, Lin; Ali, Muhammad; Oshiki, Mamoru; Ishii, Satoshi; Okabe, Satoshi

    2017-01-01

    Phylogenetically diverse anammox bacteria have been detected in most of anoxic natural and engineered ecosystems and thus regarded as key players in the global nitrogen cycle. However, ecological niche differentiation of anammox bacteria remains unresolved despite its ecological and practical importance. In this study, the microbial competitions for a common substrate (nitrite) among three anammox species (i.e. “Candidatus Brocadia sinica”, “Candidatus Jettenia caeni” and “Candidatus Kuenenia stuttgartiensis”) were systematically investigated in nitrite-limited gel-immobilized column reactors (GICR) and membrane bioreactors (MBRs) under different nitrogen loading rates (NLRs). 16 S rRNA gene-based population dynamics revealed that “Ca. J. caeni” could proliferate only at low NLRs, whereas “Ca. B. sinica” outcompeted other two species at higher NLRs in both types of reactors. Furthermore, FISH analysis revealed that “Ca. J. caeni” was mainly present as spherical microclusters at the inner part (low NO2− environment), whereas “Ca. B. sinica” was present throughout the gel beads and granules. This spatial distribution supports the outcomes of the competition experiments. However, the successful competition of “Ca. J. caeni” at low NLR could not be explained with the Monod model probably due to inaccuracy of kinetic parameters such as half saturation constant (Ks) for nitrite and a difference in the maintenance rate (m). In addition, the growth of “Ca. K. stuttgartiensis” could not be observed in any experimental conditions, suggesting possible unknown factor(s) is missing. Taken together, NLR was one of factors determining ecological niche differentiation of “Ca. B. sinica” and “Ca. J. caeni”.

  18. Nitrate ammonification in mangrove soils: A hidden source of nitrite?

    Directory of Open Access Journals (Sweden)

    Melike eBalk

    2015-03-01

    Full Text Available Nitrate reduction is considered to be a minor microbial pathway in the oxidation of mangrove-derived organic matter due to a limited supply of nitrate in mangrove soils. At a limited availability of this electron acceptor compared to the supply of degradable carbon, nitrate ammonification is thought to be the preferential pathway of nitrate reduction. Mangrove forest mutually differ in their productivity, which may lead to different available carbon to nitrate ratios in their soil. Hence, nitrate ammonification is expected to be of more importance in high- compared to low-productive forests.The hypothesis was tested in flow-through reactors that contain undisturbed mangrove soils from high-productive Avicennia germinans and Rhizophora mangle forests in Florida and low-productive Avicennia marina forests in Saudi Arabia. Nitrate was undetectable in the soils from both regions. It was assumed that a legacy of nitrate ammonification would be reflected by a higher ammonium production from these soils upon the addition of nitrate. Unexpectedly, the soils from the low-productive forests in Saudi Arabia produced considerably more ammonium than the soils from the high-productive forests in Florida. Hence, other environmental factors than productivity must govern the selection of nitrate ammonification or denitrification. A rather intriguing observation was the 1:1 production of nitrite and ammonium during the consumption of nitrate, more or less independent from sampling region, location, sampling depth, mangrove species and from the absence or presence of additional degradable carbon. This 1:1 ratio points to a coupled production of ammonium and nitrite by one group of nitrate-reducing microorganisms. Such a production of nitrite will be hidden under the nitrate-limited conditions of most mangrove forest soils.

  19. Microbial competition among anammox bacteria in nitrite-limited bioreactors

    KAUST Repository

    Zhang, Lei

    2017-08-26

    Phylogenetically diverse anammox bacteria have been detected in most of anoxic natural and engineered ecosystems and thus regarded as key players in the global nitrogen cycle. However, ecological niche differentiation of anammox bacteria remains unresolved despite its ecological and practical importance. In this study, the microbial competitions for a common substrate (nitrite) among three anammox species (i.e. “Candidatus Brocadia sinica”, “Candidatus Jettenia caeni” and “Candidatus Kuenenia stuttgartiensis”) were systematically investigated in nitrite-limited gel-immobilized column reactors (GICR) and membrane bioreactors (MBRs) under different nitrogen loading rates (NLRs). 16 S rRNA gene-based population dynamics revealed that “Ca. J. caeni” could proliferate only at low NLRs, whereas “Ca. B. sinica” outcompeted other two species at higher NLRs in both types of reactors. Furthermore, FISH analysis revealed that “Ca. J. caeni” was mainly present as spherical microclusters at the inner part (low NO2− environment), whereas “Ca. B. sinica” was present throughout the gel beads and granules. This spatial distribution supports the outcomes of the competition experiments. However, the successful competition of “Ca. J. caeni” at low NLR could not be explained with the Monod model probably due to inaccuracy of kinetic parameters such as half saturation constant (Ks) for nitrite and a difference in the maintenance rate (m). In addition, the growth of “Ca. K. stuttgartiensis” could not be observed in any experimental conditions, suggesting possible unknown factor(s) is missing. Taken together, NLR was one of factors determining ecological niche differentiation of “Ca. B. sinica” and “Ca. J. caeni”.

  20. Calcium absorption and achlorhydria

    International Nuclear Information System (INIS)

    Recker, R.R.

    1985-01-01

    Defective absorption of calcium has been thought to exist in patients with achlorhydria. The author compared absorption of calcium in its carbonate form with that in a pH-adjusted citrate form in a group of 11 fasting patients with achlorhydria and in 9 fasting normal subjects. Fractional calcium absorption was measured by a modified double-isotope procedure with 0.25 g of calcium used as the carrier. Mean calcium absorption (+/- S.D.) in the patients with achlorhydria was 0.452 +/- 0.125 for citrate and 0.042 +/- 0.021 for carbonate (P less than 0.0001). Fractional calcium absorption in the normal subjects was 0.243 +/- 0.049 for citrate and 0.225 +/- 0.108 for carbonate (not significant). Absorption of calcium from carbonate in patients with achlorhydria was significantly lower than in the normal subjects and was lower than absorption from citrate in either group; absorption from citrate in those with achlorhydria was significantly higher than in the normal subjects, as well as higher than absorption from carbonate in either group. Administration of calcium carbonate as part of a normal breakfast resulted in completely normal absorption in the achlorhydric subjects. These results indicate that calcium absorption from carbonate is impaired in achlorhydria under fasting conditions. Since achlorhydria is common in older persons, calcium carbonate may not be the ideal dietary supplement

  1. Excessive nitrite affects zebrafish valvulogenesis through yielding too much NO signaling.

    Directory of Open Access Journals (Sweden)

    Junbo Li

    Full Text Available Sodium nitrite, a common food additive, exists widely not only in the environment but also in our body. Excessive nitrite causes toxicological effects on human health; however, whether it affects vertebrate heart valve development remains unknown. In vertebrates, developmental defects of cardiac valves usually lead to congenital heart disease. To understand the toxic effects of nitrite on valvulogenesis, we exposed zebrafish embryos with different concentrations of sodium nitrite. Our results showed that sodium nitrite caused developmental defects of zebrafish heart dose dependently. It affected zebrafish heart development starting from 36 hpf (hour post fertilization when heart initiates looping process. Comprehensive analysis on the embryos at 24 hpf and 48 hpf showed that excessive nitrite did not affect blood circulation, vascular network, myocardium and endocardium development. But development of endocardial cells in atrioventricular canal (AVC of the embryos at 48 hpf was disrupted by too much nitrite, leading to defective formation of primitive valve leaflets at 76 hpf. Consistently, excessive nitrite diminished expressions of valve progenitor markers including bmp4, has2, vcana and notch1b at 48 hpf. Furthermore, 3', 5'-cyclic guanosine monophosphate (cGMP, downstream of nitric oxide (NO signaling, was increased its level significantly in the embryos exposed with excessive nitrite and microinjection of soluble guanylate cyclase inhibitor ODQ (1H-[1], [2], [4]Oxadiazolo[4,3-a] quinoxalin-1-one, an antagonist of NO signaling, into nitrite-exposed embryos could partly rescue the cardiac valve malformation. Taken together, our results show that excessive nitrite affects early valve leaflet formation by producing too much NO signaling.

  2. Rapid visual and spectrophotometric nitrite detection by cyclometalated ruthenium complex.

    Science.gov (United States)

    Lo, Hoi-Shing; Lo, Ka-Wai; Yeung, Chi-Fung; Wong, Chun-Yuen

    2017-10-16

    Quantitative determination of nitrite ion (NO 2 - ) is of great importance in environmental and clinical investigations. A rapid visual and spectrophotometric assay for NO 2 - detection was developed based on a newly designed ruthenium complex, [Ru(npy)([9]aneS3)(CO)](ClO 4 ) (denoted as RuNPY; npy = 2-(1-naphthyl)pyridine, [9]aneS3 = 1,4,7-trithiacyclononane). This complex traps NO + produced in acidified NO 2 - solution, and yields observable color change within 1 min at room temperature. The assay features excellent dynamic range (1-840 μmol L -1 ) and high selectivity, and its limit of detection (0.39 μmol L -1 ) is also well below the guideline values for drinking water recommended by WHO and U.S. EPA. Practical use of this assay in tap water and human urine was successfully demonstrated. Overall, the rapidity and selectivity of this assay overcome the problems suffered by the commonly used modified Griess assays for nitrite determination. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Calcium channel blocker poisoning

    Directory of Open Access Journals (Sweden)

    Miran Brvar

    2005-04-01

    Full Text Available Background: Calcium channel blockers act at L-type calcium channels in cardiac and vascular smooth muscles by preventing calcium influx into cells with resultant decrease in vascular tone and cardiac inotropy, chronotropy and dromotropy. Poisoning with calcium channel blockers results in reduced cardiac output, bradycardia, atrioventricular block, hypotension and shock. The findings of hypotension and bradycardia should suggest poisoning with calcium channel blockers.Conclusions: Treatment includes immediate gastric lavage and whole-bowel irrigation in case of ingestion of sustainedrelease products. All patients should receive an activated charcoal orally. Specific treatment includes calcium, glucagone and insulin, which proved especially useful in shocked patients. Supportive care including the use of catecholamines is not always effective. In the setting of failure of pharmacological therapy transvenous pacing, balloon pump and cardiopulmonary by-pass may be necessary.

  4. Metabolic fates and effects of nitrite in brown trout under normoxic and hypoxic conditions: blood and tissue nitrite metabolism and interactions with branchial NOS, Na+/K+-ATPase and hsp70 expression

    DEFF Research Database (Denmark)

    Jensen, Frank Bo; Gerber, Lucie; Hansen, Marie Niemann

    2015-01-01

    were higher in hypoxia than normoxia, suggesting increased NOS activity. Nitrite exposure strongly elevated nitrite concentrations in plasma, erythrocytes, heart tissue and white muscle, which was associated with an extensive metabolism of nitrite to nitrate and to iron-nitrosylated and S......Nitrite secures essential nitric oxide (NO) bioavailability in hypoxia at low endogenous concentrations, whereas it becomes toxic at high concentrations. We exposed brown trout to normoxic and hypoxic water in the absence and presence of added ambient nitrite to decipher the cellular metabolism...... and effects of nitrite at basal and elevated concentrations under different oxygen regimes. We also tested hypotheses concerning the influence of nitrite on branchial nitric oxide synthase (NOS), Na+/K+-ATPase (nka) and heat shock protein (hsp70) mRNA expression. Basal plasma and erythrocyte nitrite levels...

  5. Spectrofluorometric and Molecular Modeling Studies on Binding of Nitrite Ion with Bovine Hemoglobin: Effect of Nitrite Ion on Amino Acid Residues

    Science.gov (United States)

    Madrakian, T.; Bagheri, H.; Afkhami, A.

    2015-05-01

    The interaction between nitrite ion and bovine hemoglobin was investigated by a spectrofluorometric technique. The experimental results indicated that the interaction causes a static quenching of the fluorescence of bovine hemoglobin, that the binding reaction is spontaneous, and that H-bonding interactions play a major role in binding of this ion to bovine hemoglobin. The formation constant for this interaction was calculated. Based on Förster's theory of nonradiative energy transfer, the binding distance between this ion and bovine hemoglobin was determined. Furthermore, the interaction of nitrite ion with tyrosine and tryptophan was investigated with synchronous fluorescence. There was no significant shift of the maximum emission wavelength with interactions of the mentioned ion with bovine hemoglobin, which implies that interaction of nitrite ion with bovine hemoglobin does not affect the microenvironment around the tryptophan and tyrosine residues. Furthermore, the effect of nitrite ion on amino acid residues of bovine hemoglobin was studied by a molecular docking technique.

  6. Dengue and Calcium

    OpenAIRE

    Shivanthan, Mitrakrishnan C; Rajapakse, Senaka

    2014-01-01

    Dengue is potentially fatal unless managed appropriately. No specific treatment is available and the mainstay of treatment is fluid management with careful monitoring, organ support, and correction of metabolic derangement. Evidence with regards to the role of calcium homeostasis in dengue is limited. Low blood calcium levels have been demonstrated in dengue infection and hypocalcemia maybe more pronounced in more severe forms. The cause of hypocalcemia is likely to be multifactorial. Calcium...

  7. Calcium Channel Blockers

    Science.gov (United States)

    ... Certain calcium channel blockers interact with grapefruit products. Kaplan NM, et al. Treatment of hypertension: Drug therapy. In: Kaplan's Clinical Hypertension. 11th ed. Philadelphia, Pa.: Wolters Kluwer ...

  8. Effect of Electrolytes on the Adsorption of Nitrite and Nitrate from ...

    African Journals Online (AJOL)

    Nitrite and nitrate levels were quantitatively adsorbed to wood-derived activated carbon in aqueous system and the effects of electrolytes investigated in this study using batch sorption process. The data showed that nitrate adsorbed nearly 1.5 times higher than that of nitrite. The adsorption is adequately explained by ...

  9. Green Alternatives to Nitrates and Nitrites in Meat-based Products-A Review.

    Science.gov (United States)

    Gassara, Fatma; Kouassi, Anne Patricia; Brar, Satinder Kaur; Belkacemi, Khaled

    2016-10-02

    Several food additives are added in food for their preservation to maintain the freshness of food (antioxidants) or to slow down or stop the growth of microorganisms (preservative agents). Nitrites and nitrates are used as preservative agents in meat. Nitrites give a smoked taste, a pinkish color in the meat and protect the consumers against the risk of bacterial deterioration. Their addition is however very limited as, in high dose, it can have risks on human health and the environment. Nitrites may also combine with secondary or tertiary amines to form N-nitroso derivatives. Certain N-nitroso compounds have been shown to produce cancers in a wide range of laboratory animals. Thus, alternatives of nitrates and nitrites are the object of numerous research studies. Alternatives, such as the addition of vitamins, fruits, chemicals products, natural products containing nitrite or spices, which have similar properties of nitrites, are in evaluation. In fact, spices are considered to have several organoleptic and anti-microbial properties which would be interesting to study. Several spices and combinations of spices are being progressively evaluated. This review discusses the sources of nitrites and nitrates, their use as additives in food products, their physicochemical properties, their negatives effects and the use of alternatives of nitrites and nitrates in preserving meat products.

  10. Effect of sodium nitrite on toxin production by Clostridium botulinum in bacon.

    Science.gov (United States)

    Christiansen, L N; Tompkin, R B; Shaparis, A B; Kueper, T V; Johnston, R W; Kautter, D A; Kolari, O J

    1974-04-01

    Pork bellies were formulated to 0, 30, 60, 120, 170, or 340 mug of nitrite per g of meat and inoculated with Clostridium botulinum via pickle or after processing and slicing. Processed bacon was stored at 7 or 27 C and assayed for nitrite, nitrate, and botulinal toxin at different intervals. Nitrite levels declined during processing and storage. The rate of decrease was more rapid at 27 than at 7 C. Although not added to the system, nitrate was detected in samples during processing and storage at 7 and 27 C. The amount of nitrate found was related to formulated nitrite levels. No toxin was found in samples incubated at 7 C throughout the 84-day test period. At 27 C, via pickle, inoculated samples with low inoculum (210 C. botulinum per g before processing and 52 per g after processing) became toxic if formulated with 120 mug of nitrite per g of meat or less. Toxin was not detected in bacon formulated with 170 or 340 mug of nitrite per g of meat under these same conditions. Toxin was detected at all formulated nitrite levels in bacon inoculated via the pickle with 19,000 C. botulinum per g (4,300 per g after processing) and in samples inoculated after slicing. However, increased levels of formulated nitrite decreased the probability of botulinal toxin formation in bacon inoculated by both methods.

  11. Nitrate and nitrite content in bottled beverages by ion-pair high-performance liquid chromatography.

    Science.gov (United States)

    Song, Yang; Deng, Gui-Fang; Xu, Xiang-Rong; Chen, Yong-Hong; Chen, Feng; Li, Hua-Bin

    2013-01-01

    Nitrate and nitrite levels in six types of beverages--total of 292 individual samples from 73 brands (four bottles each)--from Guangzhou city in China were evaluated by ion-pair high-performance liquid chromatography. All samples contained nitrate. Nitrate and nitrite ranges were 0.43-46.08 and safety of Chinese bottled beverages.

  12. The effect of environmental hypercapnia and size on nitrite toxicity in the striped catfish (Pangasianodon hypophthalmus)

    DEFF Research Database (Denmark)

    Hvas, Malthe; Damsgaard, Christian; Gam, Le Thi Hong

    2016-01-01

    Striped catfish (Pangasianodon hypophthalmus) are farmed intensively at high stocking densities in Vietnam where they are likely to encounter environmental hypercapnia as well as occasional high levels of aquatic nitrite. Nitrite competes with Cl- for uptake at the branchial HCO3-/Cl- exchanger, ...... the ambient concentration, while small fish did not. Small P. hypophthalmus instead had significantly higher plasma [nitrate], and haemoglobin concentrations, revealing greater capacity for detoxifying nitrite by oxidising it to nitrate.......Striped catfish (Pangasianodon hypophthalmus) are farmed intensively at high stocking densities in Vietnam where they are likely to encounter environmental hypercapnia as well as occasional high levels of aquatic nitrite. Nitrite competes with Cl- for uptake at the branchial HCO3-/Cl- exchanger...... to a reduced nitrite uptake. To assess the effect of hypercapnia on nitrite uptake, fish were cannulated in the dorsal aorta, allowing repeated blood sampling for measurements of haemoglobin derivatives, plasma ions and acid-base status during exposure to 0.9 mM nitrite alone and in combination with acute...

  13. Electrochemical Biosensor for Nitrite Based on Polyacrylic-Graphene Composite Film with Covalently Immobilized Hemoglobin

    Directory of Open Access Journals (Sweden)

    Raja Zaidatul Akhmar Raja Jamaluddin

    2018-04-01

    Full Text Available A new biosensor for the analysis of nitrite in food was developed based on hemoglobin (Hb covalently immobilized on the succinimide functionalized poly(n-butyl acrylate-graphene [poly(nBA-rGO] composite film deposited on a carbon-paste screen-printed electrode (SPE. The immobilized Hb on the poly(nBA-rGO conducting matrix exhibited electrocatalytic ability for the reduction of nitrite with significant enhancement in the reduction peak at −0.6 V versus Ag/AgCl reference electrode. Thus, direct determination of nitrite can be achieved by monitoring the cathodic peak current signal of the proposed polyacrylic-graphene hybrid film-based voltammetric nitrite biosensor. The nitrite biosensor exhibited a reproducible dynamic linear response range from 0.05–5 mg L−1 nitrite and a detection limit of 0.03 mg L−1. No significant interference was observed by potential interfering ions such as Ca2+, Na+, K+, NH4+, Mg2+, and NO3− ions. Analysis of nitrite in both raw and processed edible bird’s nest (EBN samples demonstrated recovery of close to 100%. The covalent immobilization of Hb on poly(nBA-rGO composite film has improved the performance of the electrochemical nitrite biosensor in terms of broader detection range, lower detection limit, and prolonged biosensor stability.

  14. Electrochemical detection of nitrite based on the polythionine/carbon nanotube modified electrode

    International Nuclear Information System (INIS)

    Deng, Chunyan; Chen, Jinzhuo; Nie, Zhou; Yang, Minghui; Si, Shihui

    2012-01-01

    In this paper, thionine was electro-polymerized onto the surface of carbon nanotube (CNT)-modified glassy carbon (GC) to fabricate the polythionine (PTH)/CNT/GC electrode. It was found that the electro-reduction current of nitrite was enhanced greatly at the PTH/CNT/GC electrode. It may be demonstrated that PTH was used as a mediator for electrocatalytic reduction of nitrite, and CNTs as an excellent nanomaterial can improve the electron transfer between the electrode and nitrite. Therefore, based on the synergic effect of PTH and CNTs, the PTH/CNT/GC electrode was employed to detect nitrite, and the high sensitivity of 5.81 μA mM −1 , and the detection limit of 1.4 × 10 −6 M were obtained. Besides, the modified electrode showed an inherent stability, fast response time, and good anti-interference ability. These suggested that the PTH/CNT/GC electrode was favorable and reliable for the detection of nitrite. - Highlights: ► Polythionine (PTH) was used as a mediator for electrocatalytic reduction of nitrite. ► Carbon nanotubes (CNTs) improve electron transfer between the electrode and nitrite. ► The PTH/CNT/glassy carbon electrode showed excellent nitrite detection performance.

  15. Bioavailability of sodium nitrite from an aqueous solution in healthy adults.

    NARCIS (Netherlands)

    Hunault, C.C.; van Velzen, A.G.; Sips, A.J.; Schothorst, R.C.; Meulenbelt, J.|info:eu-repo/dai/nl/079479227

    2009-01-01

    Nitrate intake in humans is high through intake of vegetables such as beets, lettuce, and spinach. Nitrate itself is a compound of low toxicity but its metabolite, nitrite, formed by bacteria in the oral cavity and gastrointestinal tract, has been suspected of potential carcinogenic effects. Nitrite

  16. The use of atmospheric pressure plasma-treated water as a source of nitrite for emulsion-type sausage.

    Science.gov (United States)

    Jung, Samooel; Kim, Hyun Joo; Park, Sanghoo; In Yong, Hae; Choe, Jun Ho; Jeon, Hee-Joon; Choe, Wonho; Jo, Cheorun

    2015-10-01

    We investigated the possible use of atmospheric pressure plasma-treated water (PTW) as a nitrite source in curing process. Emulsion-type sausages were manufactured with PTW, celery powder containing nitrite, and synthetic sodium nitrite at a concentration of nitrite ion 70mgkg(-1). In terms of sausage quality, there were no noticeable effects of PTW on the total aerobic bacterial counts, color, and peroxide values of sausages compared with those of celery powder and sodium nitrite throughout 28days of storage at 4°C. Sausage with added PTW had lower concentrations of residual nitrite compared to those of added celery powder and sodium nitrite during the storage period (Pnitrite-treated sausages were not different, whereas the sausage with added celery powder received the lowest scores in taste and acceptability. From the results, it is concluded that PTW can be used as a nitrite source equivalent to a natural curing agent. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Electrochemical Single‐Molecule AFM of the Redox Metalloenzyme Copper Nitrite Reductase in Action

    DEFF Research Database (Denmark)

    Hao, Xian; Zhang, Jingdong; Christensen, Hans Erik Mølager

    2012-01-01

    We studied the electrochemical behavior of the redox metalloenzyme copper nitrite reductase (CNiR, Achromobacter xylosoxidans) immobilized on a Au(111)‐electrode surface modified by a self‐assembled cysteamine molecular monolayer (SAM) using a combination of cyclic voltammetry and electrochemically......‐controlled atomic force microscopy (in situ AFM). The enzyme showed no voltammetric signals in the absence of nitrite substrate, whereas a strong reductive electrocatalytic signal appeared in the presence of nitrite. Such a pattern is common in protein film and monolayer voltammetry and points to conformational...... in the presence of nitrite. No change in size was observed in the absence of nitrite over the same potential range. The enzyme size variation is suggested to offer clues to the broadly observed substrate triggering in metalloenzyme monolayer voltammetry....

  18. Evaluation of nitrite contamination in baby foods and infant formulas marketed in Turkey.

    Science.gov (United States)

    Erkekoglu, Pinar; Baydar, Terken

    2009-05-01

    Nitrites are responsible for methemoglobinemia, to which infants younger than 6 months are thought to be the most susceptible population. This study aimed to detect whether there was any nitrite contamination in infant formulas and baby foods marketed in Turkey and to estimate possible toxicological risks in this sensitive physiological period. For this purpose, the samples were randomly collected and divided into four groups: milk-based, cereal-based, vegetable-based, and fruit-based. An easy and reliable spectrophotometric method was used by modifying the Griess method. The average nitrite contamination was found to be 204.07+/-65.80 microg/g in 42 samples, with 1,073 microg/g maximum. According to the results, baby and infant formulas include various nitrite levels; nitrite contamination might come from several sources during manufacturing, and so extreme attention must be given throughout the manufacturing process of food for infants.

  19. An effort for reducing Nitrite in the partition process by using Diphenyl Thio Urea

    International Nuclear Information System (INIS)

    Mashudi; Busron-Masduki; Damunir; Mujianto

    1996-01-01

    The existence of nitrite in the process of U-Pu partition will disturb the partition process. In addition to the reoxidization of Pu 3+ to Pu 4+ , nitrite will also react with reductor. Both reactions are not expected, so that the nitrite ion in the partition process must be eliminated or reduced as much as possible. An experiment on the nitrite elimination in the partition process was done by reacting nitrite with diphenyl thio urea. The experiment result showed that the optimum condition was achieved at a contact time of 6 minutes, at the concentration of 0.004 N (300% stoichiometric), and the elimination result was 90%. This result is competitive enough if compared with hydrazine hydroxide or amido sulphonic acid, where the contact time is 6 minutes, the excess of both reactants are 200% and 300%, and the elimination results are 60% and 50% respectively

  20. Practical Use of Nitrite and Basis for Dosage in the Manufacture of Meat Products

    DEFF Research Database (Denmark)

    Adler-Nissen, Jens; Ekgreen, Maria Helbo; Risum, Jørgen

    . The particularities of the production methods make such a quantification rather uncertain. Furthermore, some dry cured products from South Europe are made with nitrate, which slowly and only partly is converted to nitrite and further to NO during the curing process. The Danish limitations on the use of nitrate......The use of nitrite (NaNO2) in the manufacture of salted (cured) meat products has a long tradition in the industry, dating back to the early twentieth century. Nitrite serves several technological purposes, primarily by the formation of a stable red colour in the meat and the inhibition...... of the growth of Clostridium botulinum. According to an assessment report by the European Food Safety Authority (The EFSA Journal, 14, p. 1-134, 2003) all evidence points to that it is the added amount of nitrite rather than the residual amount of nitrite in the product which exerts the antimicrobial effect...

  1. Controls of nitrite oxidation in ammonia-removing biological air filters

    DEFF Research Database (Denmark)

    Juhler, Susanne; Ottosen, Lars Ditlev Mørck; Nielsen, Lars Peter

    2008-01-01

    in accumulation of nitrate rather than nitrite and a significant decline in pH. As a consequence, ammonia is removed more efficiently, but heterotrophic oxidation of odorous compounds might be inhibited.  To identify the controlling mechanisms of nitrite oxidation, full-scale biological air filters were...... activity resulting in a lowered pH and thus a decreased FA concentration, promoting further growth of NOB. Yet, in some cases a situation with a nitrate-to-nitrite ratio of 1 and moderate pH remained stable even under varying air load and water supply, suggesting that additional mechanisms were involved......In biological air filters ammonia is removed due to the action of Ammonia Oxidizing Bacteria (AOB) resulting in nitrite accumulation exceeding 100 mM. Among filters treating exhaust air from pig facilities successful establishment of Nitrite Oxidizing Bacteria (NOB) sometimes occurs, resulting...

  2. Estimation of nitrite in source-separated nitrified urine with UV spectrophotometry.

    Science.gov (United States)

    Mašić, Alma; Santos, Ana T L; Etter, Bastian; Udert, Kai M; Villez, Kris

    2015-11-15

    Monitoring of nitrite is essential for an immediate response and prevention of irreversible failure of decentralized biological urine nitrification reactors. Although a few sensors are available for nitrite measurement, none of them are suitable for applications in which both nitrite and nitrate are present in very high concentrations. Such is the case in collected source-separated urine, stabilized by nitrification for long-term storage. Ultraviolet (UV) spectrophotometry in combination with chemometrics is a promising option for monitoring of nitrite. In this study, an immersible in situ UV sensor is investigated for the first time so to establish a relationship between UV absorbance spectra and nitrite concentrations in nitrified urine. The study focuses on the effects of suspended particles and saturation on the absorbance spectra and the chemometric model performance. Detailed analysis indicates that suspended particles in nitrified urine have a negligible effect on nitrite estimation, concluding that sample filtration is not necessary as pretreatment. In contrast, saturation due to very high concentrations affects the model performance severely, suggesting dilution as an essential sample preparation step. However, this can also be mitigated by simple removal of the saturated, lower end of the UV absorbance spectra, and extraction of information from the secondary, weaker nitrite absorbance peak. This approach allows for estimation of nitrite with a simple chemometric model and without sample dilution. These results are promising for a practical application of the UV sensor as an in situ nitrite measurement in a urine nitrification reactor given the exceptional quality of the nitrite estimates in comparison to previous studies. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Food sources of nitrates and nitrites: the physiologic context for potential health benefits.

    Science.gov (United States)

    Hord, Norman G; Tang, Yaoping; Bryan, Nathan S

    2009-07-01

    The presence of nitrates and nitrites in food is associated with an increased risk of gastrointestinal cancer and, in infants, methemoglobinemia. Despite the physiologic roles for nitrate and nitrite in vascular and immune function, consideration of food sources of nitrates and nitrites as healthful dietary components has received little attention. Approximately 80% of dietary nitrates are derived from vegetable consumption; sources of nitrites include vegetables, fruit, and processed meats. Nitrites are produced endogenously through the oxidation of nitric oxide and through a reduction of nitrate by commensal bacteria in the mouth and gastrointestinal tract. As such, the dietary provision of nitrates and nitrites from vegetables and fruit may contribute to the blood pressure-lowering effects of the Dietary Approaches to Stop Hypertension (DASH) diet. We quantified nitrate and nitrite concentrations by HPLC in a convenience sample of foods. Incorporating these values into 2 hypothetical dietary patterns that emphasize high-nitrate or low-nitrate vegetable and fruit choices based on the DASH diet, we found that nitrate concentrations in these 2 patterns vary from 174 to 1222 mg. The hypothetical high-nitrate DASH diet pattern exceeds the World Health Organization's Acceptable Daily Intake for nitrate by 550% for a 60-kg adult. These data call into question the rationale for recommendations to limit nitrate and nitrite consumption from plant foods; a comprehensive reevaluation of the health effects of food sources of nitrates and nitrites is appropriate. The strength of the evidence linking the consumption of nitrate- and nitrite-containing plant foods to beneficial health effects supports the consideration of these compounds as nutrients.

  4. Crosstalk between nitrite, myoglobin and reactive oxygen species to regulate vasodilation under hypoxia.

    Directory of Open Access Journals (Sweden)

    Matthias Totzeck

    Full Text Available The systemic response to decreasing oxygen levels is hypoxic vasodilation. While this mechanism has been known for more than a century, the underlying cellular events have remained incompletely understood. Nitrite signaling is critically involved in vessel relaxation under hypoxia. This can be attributed to the presence of myoglobin in the vessel wall together with other potential nitrite reductases, which generate nitric oxide, one of the most potent vasodilatory signaling molecules. Questions remain relating to the precise concentration of nitrite and the exact dose-response relations between nitrite and myoglobin under hypoxia. It is furthermore unclear whether regulatory mechanisms exist which balance this interaction. Nitrite tissue levels were similar across all species investigated. We then investigated the exact fractional myoglobin desaturation in an ex vivo approach when gassing with 1% oxygen. Within a short time frame myoglobin desaturated to 58±12%. Given that myoglobin significantly contributes to nitrite reduction under hypoxia, dose-response experiments using physiological to pharmacological nitrite concentrations were conducted. Along all concentrations, abrogation of myoglobin in mice impaired vasodilation. As reactive oxygen species may counteract the vasodilatory response, we used superoxide dismutase and its mimic tempol as well as catalase and ebselen to reduce the levels of reactive oxygen species during hypoxic vasodilation. Incubation of tempol in conjunction with catalase alone and catalase/ebselen increased the vasodilatory response to nitrite. Our study shows that modest hypoxia leads to a significant nitrite-dependent vessel relaxation. This requires the presence of vascular myoglobin for both physiological and pharmacological nitrite levels. Reactive oxygen species, in turn, modulate this vasodilation response.

  5. Acidosis and Urinary Calcium Excretion

    DEFF Research Database (Denmark)

    Alexander, R Todd; Cordat, Emmanuelle; Chambrey, Régine

    2016-01-01

    Metabolic acidosis is associated with increased urinary calcium excretion and related sequelae, including nephrocalcinosis and nephrolithiasis. The increased urinary calcium excretion induced by metabolic acidosis predominantly results from increased mobilization of calcium out of bone and inhibi...

  6. Intake assessment of the food additives nitrite (E 249 and E 250) and nitrate (E 251 and E 252)

    NARCIS (Netherlands)

    Sprong RC; Niekerk EM; Beukers MH; VVH; V&Z

    2017-01-01

    Nitrate and nitrite are authorised as preservatives in certain food products, such as salami, ham (nitrite) and cheese (nitrate). They prevent food spoilage and protect the consumer against food-borne pathogens. Next to that, nitrate and nitrite play a role in food colour retention and contribute to

  7. Calcium D-saccharate

    DEFF Research Database (Denmark)

    Garcia, André Castilho; Hedegaard, Martina Vavrusova; Skibsted, Leif Horsfelt

    2016-01-01

    Molar conductivity of saturated aqueous solutions of calcium d-saccharate, used as a stabilizer of beverages fortified with calcium d-gluconate, increases strongly upon dilution, indicating complex formation between calcium and d-saccharate ions, for which, at 25 °C, Kassoc = 1032 ± 80, ΔHassoc......° = -34 ± 6 kJ mol-1, and ΔSassoc° = -55 ± 9 J mol-1 K-1, were determined electrochemically. Calcium d-saccharate is sparingly soluble, with a solubility product, Ksp, of (6.17 ± 0.32) × 10-7 at 25 °C, only moderately increasing with the temperature: ΔHsol° = 48 ± 2 kJ mol-1, and ΔSassoc° = 42 ± 7 J mol-1...... K-1. Equilibria in supersaturated solutions of calcium d-saccharate seem only to adjust slowly, as seen from calcium activity measurements in calcium d-saccharate solutions made supersaturated by cooling. Solutions formed by isothermal dissolution of calcium d-gluconate in aqueous potassium d...

  8. Calcium metabolism in birds.

    Science.gov (United States)

    de Matos, Ricardo

    2008-01-01

    Calcium is one of the most important plasma constituents in mammals and birds. It provides structural strength and support (bones and eggshell) and plays vital roles in many of the biochemical reactions in the body. The control of calcium metabolism in birds is highly efficient and closely regulated in a number of tissues, primarily parathyroid gland, intestine, kidney, and bone. The hormones with the greatest involvement in calcium regulation in birds are parathyroid hormone, 1,25-dihydroxyvitamin D(3) (calcitriol), and estrogen, with calcitonin playing a minor and uncertain role. The special characteristics of calcium metabolism in birds, mainly associated with egg production, are discussed, along with common clinical disorders secondary to derangements in calcium homeostasis.

  9. Role of xanthine oxidoreductase in the anti-thrombotic effects of nitrite in rats in vivo.

    Science.gov (United States)

    Kramkowski, K; Leszczynska, A; Przyborowski, K; Kaminski, T; Rykaczewska, U; Sitek, B; Zakrzewska, A; Proniewski, B; Smolenski, R T; Chabielska, E; Buczko, W; Chlopicki, S

    2016-01-01

    The mechanisms underlying nitrite-induced effects on thrombosis and hemostasis in vivo are not clear. The goal of the work described here was to investigate the role of xanthine oxidoreductase (XOR) in the anti-platelet and anti-thrombotic activities of nitrite in rats in vivo. Arterial thrombosis was induced electrically in rats with renovascular hypertension by partial ligation of the left renal artery. Sodium nitrite (NaNO2, 0.17 mmol/kg twice daily for 3 days, p.o) was administered with or without one of the XOR-inhibitors: allopurinol (ALLO) and febuxostat (FEB) (100 and 5 mg/kg, p.o., for 3 days). Nitrite treatment (0.17 mmol/kg), which was associated with a significant increase in NOHb, nitrite/nitrate plasma concentration, resulted in a substantial decrease in thrombus weight (TW) (0.48 ± 0.03 mg vs. vehicle [VEH] 0.88 ± 0.08 mg, p < 0.001) without a significant hypotensive effect. The anti-thrombotic effect of nitrite was partially reversed by FEB (TW = 0.63 ± 0.06 mg, p < 0.05 vs. nitrites), but not by ALLO (TW = 0.43 ± 0.02 mg). In turn, profound anti-platelet effect of nitrite measured ex vivo using collagen-induced whole-blood platelet aggregation (70.5 ± 7.1% vs. VEH 100 ± 4.5%, p < 0.05) and dynamic thromboxaneB2 generation was fully reversed by both XOR-inhibitors. In addition, nitrite decreased plasminogen activator inhibitor-1 concentration (0.47 ± 0.13 ng/ml vs. VEH 0.62 ± 0.04 ng/ml, p < 0.05) and FEB/ALLO reversed this effect. In vitro the anti-platelet effect of nitrite (1 mM) was reversed by FEB (0.1 mM) under hypoxia (0.5%O2) and normoxia (20%O2). Nitrite treatment had no effect on coagulation parameters. In conclusion, the nitrite-induced anti-platelet effect in rats in vivo is mediated by XOR, but XOR does not fully account for the anti-thrombotic effects of nitrite.

  10. Addition of nitrite enhances the electrochemical defluorination of 2-fluoroaniline

    International Nuclear Information System (INIS)

    Feng, Huajun; Liang, Yuxiang; Guo, Kun; Long, Yuyang; Cong, Yanqing; Shen, Dongsheng

    2015-01-01

    Highlights: • A method for improving defluorination performance by in situ self-assembly of pollutants was developed. • The mechanisms of 2-FA modification and defluorination are discussed. • Positively-charged diazonium salt is used to weaken the C–F bond. - Abstract: This study introduces a novel approach that uses the interaction of pollutants with added nitrite to produce diazonium salts, which cause in situ self-assembly of the pollutants on carbon electrodes, to improve their 2-fluoroaniline (2-FA) defluorination and removal performance. The 2-FA degradation performance, electrode properties, electrochemical properties and degradation pathway were investigated. The reactor containing NO_2"− achieved a 2-FA removal efficiency of 90.1% and a defluorination efficiency of 38% within 48 h, 1.4 and 2.3 times higher than the corresponding results achieved without NO_2"−, respectively. The residual NO_2"− was less than 0.5 mg/L in the reactor containing added NO_2"−, which would not cause serious secondary pollution. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) results proved that the carbon anode surface was successfully modified with benzene polymer, and electrochemical tests confirmed that the electrochemical activity of the modified anode was enhanced significantly. The C–F bond was weakened by the effect of the positive charge of the benzenediazonium groups, and the high electrochemical activity of the carbon anode enhanced the electrochemical performance of the system to accelerate defluorination. Thus, the present electrical method involving nitrite nitrogen is very promising for the treatment of wastewater containing fluoroaniline compounds.

  11. Addition of nitrite enhances the electrochemical defluorination of 2-fluoroaniline

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Huajun [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012 (China); Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012 (China); Laboratory of Microbial Ecology and Technology, Ghent University, Coupure Links 653, B-9000 Ghent (Belgium); Liang, Yuxiang [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012 (China); Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012 (China); Guo, Kun [Laboratory of Microbial Ecology and Technology, Ghent University, Coupure Links 653, B-9000 Ghent (Belgium); Long, Yuyang [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012 (China); Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012 (China); Cong, Yanqing, E-mail: yqcong@hotmail.com [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012 (China); Shen, Dongsheng [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012 (China); Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012 (China)

    2015-12-30

    Highlights: • A method for improving defluorination performance by in situ self-assembly of pollutants was developed. • The mechanisms of 2-FA modification and defluorination are discussed. • Positively-charged diazonium salt is used to weaken the C–F bond. - Abstract: This study introduces a novel approach that uses the interaction of pollutants with added nitrite to produce diazonium salts, which cause in situ self-assembly of the pollutants on carbon electrodes, to improve their 2-fluoroaniline (2-FA) defluorination and removal performance. The 2-FA degradation performance, electrode properties, electrochemical properties and degradation pathway were investigated. The reactor containing NO{sub 2}{sup −} achieved a 2-FA removal efficiency of 90.1% and a defluorination efficiency of 38% within 48 h, 1.4 and 2.3 times higher than the corresponding results achieved without NO{sub 2}{sup −}, respectively. The residual NO{sub 2}{sup −} was less than 0.5 mg/L in the reactor containing added NO{sub 2}{sup −}, which would not cause serious secondary pollution. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) results proved that the carbon anode surface was successfully modified with benzene polymer, and electrochemical tests confirmed that the electrochemical activity of the modified anode was enhanced significantly. The C–F bond was weakened by the effect of the positive charge of the benzenediazonium groups, and the high electrochemical activity of the carbon anode enhanced the electrochemical performance of the system to accelerate defluorination. Thus, the present electrical method involving nitrite nitrogen is very promising for the treatment of wastewater containing fluoroaniline compounds.

  12. HYPERTHERMIA, INTRACELLULAR FREE CALCIUM AND CALCIUM IONOPHORES

    NARCIS (Netherlands)

    STEGE, GJJ; WIERENGA, PK; KAMPINGA, HH; KONINGS, AWT

    1993-01-01

    It is shown that heat-induced increase of intracellular calcium does not correlate with hyperthermic cell killing. Six different cell lines were investigated; in four (EAT, HeLa S3, L5178Y-R and L5178Y-S) heat treatments killing 90% of the cells did not affect the levels of intracellular free

  13. Effect of Ethanolamines on Corrosion Inhibition of Ductile Cast Iron in Nitrite Containing Solutions

    International Nuclear Information System (INIS)

    Kim, K. T.; Kim, Y. S.; Chang, H. Y.; Lim, B. T.; Park, H. B.

    2016-01-01

    In this work, synergistic corrosion inhibition effect of nitrite and 3 kinds of ethanolamines on ductile cast iron using chemical and electrochemical methods was evaluated. This work attempts to clarify the synergistic effect of nitrite and ethanolamines. The effects of single addition of TEA, DEA, and MEA, and mixed addition of nitrite plus TEA, DEA or MEA on the corrosion inhibition of ductile cast iron in a tap water were evaluated. A huge amount of single addition of ethanolamine was needed. However, the synergistic effect by mixed addition was observed regardless of the combination of nitrite and triethanolamines, but their effects increased in a series of MEA + nitrite > DEA + nitrite > TEA + nitrite. This tendency of synergistic effect was attributed to the film properties and polar effect; TEA addition couldn't form the film showing high film resistance and semiconductive properties, but DEA or MEA could build the film having relatively high film resistance and n-type semiconductive properties. Moreover, it can be explained that this behaviour was closely related to electron attractive group within the ethanolamines, and thus corrosion inhibition power depends upon the number of the electron attractive group of MEA, DEA, and TEA.

  14. Effect of Ethanolamines on Corrosion Inhibition of Ductile Cast Iron in Nitrite Containing Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K. T.; Kim, Y. S. [Andong National University, Andong (Korea, Republic of); Chang, H. Y.; Lim, B. T.; Park, H. B. [KEPCO Engineering and Construction Company, Gimcheon (Korea, Republic of)

    2016-08-15

    In this work, synergistic corrosion inhibition effect of nitrite and 3 kinds of ethanolamines on ductile cast iron using chemical and electrochemical methods was evaluated. This work attempts to clarify the synergistic effect of nitrite and ethanolamines. The effects of single addition of TEA, DEA, and MEA, and mixed addition of nitrite plus TEA, DEA or MEA on the corrosion inhibition of ductile cast iron in a tap water were evaluated. A huge amount of single addition of ethanolamine was needed. However, the synergistic effect by mixed addition was observed regardless of the combination of nitrite and triethanolamines, but their effects increased in a series of MEA + nitrite > DEA + nitrite > TEA + nitrite. This tendency of synergistic effect was attributed to the film properties and polar effect; TEA addition couldn't form the film showing high film resistance and semiconductive properties, but DEA or MEA could build the film having relatively high film resistance and n-type semiconductive properties. Moreover, it can be explained that this behaviour was closely related to electron attractive group within the ethanolamines, and thus corrosion inhibition power depends upon the number of the electron attractive group of MEA, DEA, and TEA.

  15. Ingested nitrate and nitrite and stomach cancer risk: an updated review.

    Science.gov (United States)

    Bryan, Nathan S; Alexander, Dominik D; Coughlin, James R; Milkowski, Andrew L; Boffetta, Paolo

    2012-10-01

    Nitrite and nitrate are naturally occurring molecules in vegetables and also added to cured and processed meats to delay spoilage and pathogenic bacteria growth. Research over the past 15 years has led to a paradigm change in our ideas about health effects of both nitrite and nitrate. Whereas, historically nitrite and nitrate were considered harmful food additives and listed as probable human carcinogens under conditions where endogenous nitrosation could take place, they are now considered by some as indispensible nutrients essential for cardiovascular health by promoting nitric oxide (NO) production. We provide an update to the literature and knowledge base concerning their safety. Most nitrite and nitrate exposure comes from naturally occurring and endogenous sources and part of the cell signaling effects of NO involve nitrosation. Nitrosation must now be considered broadly in terms of both S- and N-nitrosated species, since S-nitrosation is kinetically favored. Protein S-nitrosation is a significant part of the role of NO in cellular signal transduction and is involved in critical aspects of cardiovascular health. A critical review of the animal toxicology literature of nitrite indicates that in the absence of co-administration of a carcinogenic nitrosamine precursor, there is no evidence for carcinogenesis. Newly published prospective epidemiological cohort studies indicate that there is no association between estimated intake of nitrite and nitrate in the diet and stomach cancer. This new and growing body of evidence calls for a reconsideration of nitrite and nitrate safety. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Nitrite reduction and methanogenesis in a single-stage UASB reactor.

    Science.gov (United States)

    Borges, L I; López-Vazquez, C M; García, H; van Lier, J B

    2015-01-01

    In this study, nitrite reduction and methanogenesis in a single-stage upflow anaerobic sludge blanket (UASB) reactor was investigated, using high-strength synthetic domestic wastewater as substrate. To assess long-term effects and evaluate the mechanisms that allow successful nitrite reduction and methanogenesis in a single-stage UASB, sludge was exposed to relatively high nitrite loading rates (315 ± 13 mgNO(2)(-)-N/(l.d)), using a chemical oxygen demand (COD) to nitrogen ratio of 18 gCOD/gNO(2)(-)-N, and an organic loading rate of 5.4 ± 0.2 gCOD/(l.d). In parallel, the effects of sludge morphology on methanogenesis inhibition were studied by performing short-term batch activity tests at different COD/NO(2)(-)-N ratios with anaerobic sludge samples. In long-term tests, denitrification was practically complete and COD removal efficiency did not change significantly after nitrite addition. Furthermore, methane production only decreased by 13%, agreeing with the reducing equivalents requirement for complete NO(2)(-) reduction to N₂. Apparently, the spatial separation of denitrification and methanogenesis zones inside the UASB reactor allowed nitrite reduction and methanogenesis to occur at the same moment. Batch tests showed that granules seem to protect methanogens from nitrite inhibition, probably due to transport limitations. Combined COD and N removal via nitrite in a single-stage UASB reactor could be a feasible technology to treat high-strength domestic wastewater.

  17. Nitrogen-Doped Carbon Quantum Dots as Fluorescent Probes for Sensitive and Selective Detection of Nitrite

    Directory of Open Access Journals (Sweden)

    Zhibiao Feng

    2017-11-01

    Full Text Available Nitrites are the upstream precursors of the carcinogenic nitrosamines, which are widely found in the natural environment and many food products. It is important to develop a simple and sensitive sensor for detecting nitrites. In this work, a fluorescence probe based on nitrogen-doped carbon quantum dots (N-CQDs was developed for the sensitive and selective determination of nitrites. At pH 2, the fluorescence of N-CQDs can be selectively quenched by nitrite due to the fact N-nitroso compounds can be formed in the reaction of amide groups with nitrous acid, which results in fluorescence static quenching. Under optimal conditions, fluorescence intensity quenching upon addition of nitrite gives a satisfactory linear relationship covering the linear range of 0.2–20 μM, and the limit of detection (LOD is 40 nM. Moreover, this method has been successfully applied to the determination of nitrites in tap water, which indicates its great potential for monitoring of nitrites in environmental samples.

  18. Role of nitrite in the photochemical formation of radicals in the snow.

    Science.gov (United States)

    Jacobi, Hans-Werner; Kleffmann, Jörg; Villena, Guillermo; Wiesen, Peter; King, Martin; France, James; Anastasio, Cort; Staebler, Ralf

    2014-01-01

    Photochemical reactions in snow can have an important impact on the composition of the atmosphere over snow-covered areas as well as on the composition of the snow itself. One of the major photochemical processes is the photolysis of nitrate leading to the formation of volatile nitrogen compounds. We report nitrite concentrations determined together with nitrate and hydrogen peroxide in surface snow collected at the coastal site of Barrow, Alaska. The results demonstrate that nitrite likely plays a significant role as a precursor for reactive hydroxyl radicals as well as volatile nitrogen oxides in the snow. Pollution events leading to high concentrations of nitrous acid in the atmosphere contributed to an observed increase in nitrite in the surface snow layer during nighttime. Observed daytime nitrite concentrations are much higher than values predicted from steady-state concentrations based on photolysis of nitrate and nitrite indicating that we do not fully understand the production of nitrite and nitrous acid in snow. The discrepancy between observed and expected nitrite concentrations is probably due to a combination of factors, including an incomplete understanding of the reactive environment and chemical processes in snow, and a lack of consideration of the vertical structure of snow.

  19. Preliminary nitrite, nitrate and colour analysis of Malaysian edible bird’s nest

    Directory of Open Access Journals (Sweden)

    Meei Chien Quek

    2015-05-01

    Full Text Available The high nitrite content in edible bird’s nests is a major concern to the local swiftlet industry. It lowers the price of the edible bird’s nests and it brings severe health hazards to consumers and farmers. This research investigated the nitrite and nitrate contents of eight types of local edible bird’s nests by using ion chromatography system and evaluating its colour using the CIE system in L∗a∗b∗ parameters. The nitrite content obtained ranged from 5.7 μg/g for the house nests to 843.8 μg/g for the cave nests. The nitrate content for the house and cave nests was 98.2 μg/g and 36,999.4 μg/g, respectively. The cave nests with darker and redder colour had higher nitrite and nitrate contents than the brighter and more yellow house nests. This likely suggests that the nitrite and nitrate contents have correlations with edible bird’s nests colour. Correlations studies suggested that the nitrite content had high correlations with colour parameters, L∗a∗b∗ of edible bird’s nests at significant level of P < 0.10. These findings suggest that edible bird’s nests’ colour may be a useful indicator for measuring nitrite and nitrate contaminations.

  20. Music stimuli lead to increased levels of nitrite in unstimulated mixed saliva.

    Science.gov (United States)

    Jin, Luyuan; Zhang, Mengbi; Xu, Junji; Xia, Dengsheng; Zhang, Chunmei; Wang, Jingsong; Wang, Songlin

    2018-06-15

    Concentration of salivary nitrate is approximately 10-fold to that of serum. Many circumstances such as acute stress could promote salivary nitrate secretion and nitrite formation. However, whether other conditions can also be used as regulators of salivary nitrate/nitrite has not yet been explored. The present study was designed to determine the influence of exposure to different music on the salivary flow rate and nitrate secretion and nitrite formation. Twenty-four undergraduate students (12 females and 12 males) were exposed to silence, rock music, classical music or white noise respectively on four consecutive mornings. The unstimulated salivary flow rate and stimulated salivary flow rate were measured. Salivary ionic (Na + , Ca 2+ Cl - , and PO 4 3- ) content and nitrate/nitrite levels were detected. The unstimulated salivary flow rate was significantly increased after classical music exposure compared to that after silence. Salivary nitrite levels were significantly higher upon classical music and white noise stimulation than those under silence in females. However, males were more sensitive only to white noise with regard to the nitrite increase. In conclusion, this study demonstrated that classical music stimulation promotes salivary nitrite formation and an increase in saliva volume was observed. These observations may play an important role in regulating oral function.

  1. Effect of luminal or circulating nitrite on colonic ion movement in the rat

    International Nuclear Information System (INIS)

    Radcliffe, B.C.; Nance, S.H.; Deakin, E.J.; Roediger, W.E.W.

    1987-01-01

    The disposition of intravenously or luminally administered nitrite across the colonic mucosa and its effect on ion movement into or from the colon was assessed in anesthetized Porton rats using the isolated colon instilled either with sodium chloride or sodium chloride with sodium butyrate. Ionic changes in the colon after intravenous injection of 10 μmol NaNO 2 were compared with those occurring after injection of 10 μmol NaCl. After intravenous administration of nitrite, both nitrite and nitrate appeared in the colonic instillate in a ratio of 1:1. Nitrite increased chloride absorption (110%) and bicarbonate production (20%) when 40 mM butyrate was included in the instillate. Net sodium absorption, measured in the whole colon, was unchanged. Intravenous nitrite had no effect on ionic movement in the absence of butyrate. When NaNO 2 was included luminally with the sodium chloride-butyrate instillate, bicarbonate production rate increased, but sodium and chloride absorption were unaffected. Nitrite concentration in the instillate decreased during the 40-min experimental period at a rate of 0.275 nmol·min -1 ·cm -2 and nitrate appeared at a rate of 0.037 nmol·min -1 ·cm -2 . The authors conclude that nitrite stimulates bicarbonate production in the colon, probably by stimulating the oxidation by butyrate, the main source of CO 2 generation by the colonic mucosa

  2. Effect of Sodium Nitrite and Sodium Nitrate on Botulinal Toxin Production and Nitrosamine Formation in Wieners

    Science.gov (United States)

    Hustad, Gerald O.; Cerveny, John G.; Trenk, Hugh; Deibel, Robert H.; Kautter, Donald A.; Fazio, Thomas; Johnston, Ralph W.; Kolari, Olaf E.

    1973-01-01

    Wieners were formulated and processed approximating commercial conditions as closely as possible. Twenty-four batches of product were made with the addition of six levels of sodium nitrite (0, 50, 100, 150, 200, and 300 μg/g), four levels of sodium nitrate (0, 50, 150, and 450 μg/g), and two levels of Clostridium botulinum (0 and 620 spores/g). After formulation, processing, and vacuum packaging, portions of each batch were incubated at 27 C or held for 21 days at 7 C followed by incubation at 27 C for 56 days. The latter storage condition approximated distribution of product through commercial channels and potential temperature abuse at the consumer level. Samples were analyzed for botulinal toxin, nitrite, and nitrate levels after 3, 7, 14, 21, 28, and 56 days of incubation. When nitrite was not added, toxic samples were detected after 14 days of incubation at 27 C. At the lowest level of nitrite added (50 μg/g), no toxic samples were observed until 56 days of incubation. Higher levels of nitrite completely inhibited toxin production throughout the incubation period. Nine uninoculated samples, representing various levels and combinations of nitrite and nitrate, were evaluated organoleptically. The flavor quality of wieners made with nitrite was judged significantly higher (P = 0.05) than of wieners made without nitrite. The nine samples were negative for 14 volatile nitrosamines at a sensitivity level of 10 ng/g. The results indicated that nitrite effectively inhibited botulinal toxin formation at commercially employed levels in wieners and that detectable quantities of nitrosamines were not produced during preparation and processing of the product for consumption. PMID:4580194

  3. Role of blood and vascular smooth muscle in the vasoactivity of nitrite

    Science.gov (United States)

    Liu, Taiming; Schroeder, Hobe J.; Barcelo, Lisa; Bragg, Shannon L.; Terry, Michael H.; Wilson, Sean M.; Power, Gordon G.

    2014-01-01

    Recent evidence from humans and rats indicates that nitrite is a vasodilator under hypoxic conditions by reacting with metal-containing proteins to produce nitric oxide (NO). We tested the hypothesis that near-physiological concentrations of nitrite would produce vasodilation in a hypoxia- and concentration-dependent manner in the hind limb of sheep. Anesthetized sheep were instrumented to measure arterial blood pressure and femoral blood flows continuously in both hind limbs. Nitrite was infused into one femoral artery to raise the nitrite concentration in the femoral vein by 10 to 15-fold while the sheep breathed 50%, 14% or 12% oxygen in inspired air. In contrast to reports in humans and rats, the nitrite infusion had no measurable effect on mean femoral blood flows or vascular conductances, regardless of inspired O2 levels. In vitro experiments showed no significant difference in the release of NO from nitrite in sheep and human red blood cells. Further experiments demonstrated nitrite is converted to NO in rat artery homogenates faster than sheep arteries, and that this source of NO production is attenuated in the presence of a heme oxidizer. Finally, western blots indicate that concentrations of the heme-containing protein cytoglobin, but not myoglobin, are markedly lower in sheep arteries compared with rats. Overall, the results demonstrate that nitrite is not a physiological vasodilator in sheep. This is likely due to a lack of conversion of nitrite to NO within the vascular smooth muscle, perhaps due to deficient amounts of the heme-containing protein cytoglobin. PMID:25108012

  4. Iron(II) porphyrins induced conversion of nitrite into nitric oxide: A computational study.

    Science.gov (United States)

    Zhang, Ting Ting; Liu, Yong Dong; Zhong, Ru Gang

    2015-09-01

    Nitrite reduction to nitric oxide by heme proteins was reported as a protective mechanism to hypoxic injury in mammalian physiology. In this study, the pathways of nitrite reduction to nitric oxide mediated by iron(II) porphyrin (P) complexes, which were generally recognized as models for heme proteins, were investigated by using density functional theory (DFT). In view of two type isomers of combination of nitrite and Fe(II)(P), N-nitro- and O-nitrito-Fe(II)-porphyrin complexes, and two binding sites of proton to the different O atoms of nitrite moiety, four main pathways for the conversion of nitrite into nitric oxide mediated by iron(II) porphyrins were proposed. The results indicate that the pathway of N-bound Fe(II)(P)(NO2) isomer into Fe(III)(P)(NO) and water is similar to that of O-bound isomer into nitric oxide and Fe(III)(P)(OH) in both thermodynamical and dynamical aspects. Based on the initial computational studies of five-coordinate nitrite complexes, the conversion of nitrite into NO mediated by Fe(II)(P)(L) complexes with 14 kinds of proximal ligands was also investigated. Generally, the same conclusion that the pathways of N-bound isomers are similar to those of O-bound isomer was obtained for iron(II) porphyrin with ligands. Different effects of ligands on the reduction reactions were also found. It is notable that the negative proximal ligands can improve reactive abilities of N-nitro-iron(II) porphyrins in the conversion of nitrite into nitric oxide compared to neutral ligands. The findings will be helpful to expand our understanding of the mechanism of nitrite reduction to nitric oxide by iron(II) porphyrins. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Color and oxidative stability of nitrite-free cured meat after gamma irradiation

    International Nuclear Information System (INIS)

    Shahidi, F.; Pegg, R.B.; Shamsuzzaman, K.

    1991-01-01

    The effects of 5 and 10 kGy irradiation on the color and oxidative stability of meats treated with nitrite or a nitrite-free curing system were investigated. The nitrite-free curing system consisted of the preformed cooked cured-meat pigment, sodium ascorbate and sodium tripolyphosphate with or without sodium acid pyrophosphate. Irradiation had no detrimental effects on the color or flavor of either cured samples. Polyphosphates had a beneficial effect on oxidative stability but had a slight detrimental effect on color stability of irradiated samples

  6. Solubilities of sodium nitrate, sodium nitrite, and sodium aluminate in simulated nuclear waste

    International Nuclear Information System (INIS)

    Reynolds, D.A.; Herting, D.L.

    1984-09-01

    Solubilities were determined for sodium nitrate, sodium nitrite, and sodium aluminate in synthetic nuclear waste liquor. Solubilities were determined as a function of temperature and solution composition (concentrations of sodium hydroxide, sodium nitrate, sodium nitrite, and sodium aluminate). Temperature had the greatest effect on the solubilities of sodium nitrate and sodium nitrite and a somewhat lesser effect on sodium aluminate solubility. Hydroxide had a great effect on the solubilities of all three salts. Other solution components had minor effects. 2 references, 8 figures, 11 tables

  7. Role of Nitrite in Processed Meat Products and its Degradation during their Storage

    OpenAIRE

    ILIRJANA BOCI; ELDA ZIU; GENTJANA BARDHI

    2014-01-01

    This paper represents the analytical data of nitrite level obtained from the experimental work done on meat processed samples taken from a meat processing plant in Tirana. There has been a long debate and health concern about the nitrite content in meat products. Nitrite is added to e.g. sausages, and hams and other meat products to preserve these products and keep them free from dangerous bacteria. Among the aims are preventing botulism, a dangerous food poison. But also it’s important to us...

  8. Effect of residual ascorbate on determination of nitrite in commercial cured meat products.

    Science.gov (United States)

    Fox, J B; Doerr, R C; Gates, R

    1984-01-01

    Residual ascorbate in cured meat slurries results in different amounts of pigment being produced from different Griess reagent combinations. The phenomenon was used to study residual ascorbate in commercial cured meat products which had a variety of textures, acidities, moisture and meat content, fat, homogeneity, initial nitrite, and processing conditions. Diluting and heating the samples according to the AOAC procedure did not completely eliminate the ascorbate interference, but making the sample alkaline did. Determining nitrite separately in supernate and precipitate from the first dilution showed the effect of heating to be the elimination of interferences and solubilization or extraction of nitrite from the precipitate.

  9. Occurrence of nitrate, nitrite and volatile nitrosamines in certain feedstuffs and animal products.

    Science.gov (United States)

    Ologhobo, A D; Adegede, H I; Maduagiwu, E N

    1996-01-01

    Nitrate, nitrite and nitrosamines were analysed in poultry feeds, meat and eggs. The poultry meat was boiled and roasted while the eggs were raw and boiled, and the effects of these processing treatments on the level of these compounds were investigated. Nitrate levels in the meat samples were significantly (P Nitrite levels were also reduced significantly by processing (P Nitrite levels were generally low in all feed samples. Nitrosamines were not detected in any of the feed samples and in the meat samples except in two samples of boiled meat which contained 0.001 g/kg each.

  10. Preliminary nitrite, nitrate and colour analysis of Malaysian edible bird’s nest

    OpenAIRE

    Quek, Meei Chien; Chin, Nyuk Ling; Yusof, Yus Aniza; Tan, Sheau Wei; Law, Chung Lim

    2015-01-01

    The high nitrite content in edible bird’s nests is a major concern to the local swiftlet industry. It lowers the price of the edible bird’s nests and it brings severe health hazards to consumers and farmers. This research investigated the nitrite and nitrate contents of eight types of local edible bird’s nests by using ion chromatography system and evaluating its colour using the CIE system in L∗a∗b∗ parameters. The nitrite content obtained ranged from 5.7 μg/g for the house nests to 843.8 μg...

  11. Stress Corrosion Cracking of an Austenitic Stainless Steel in Nitrite-Containing Chloride Solutions

    Directory of Open Access Journals (Sweden)

    R. K. Singh Raman

    2014-12-01

    Full Text Available This article describes the susceptibility of 316L stainless steel to stress corrosion cracking (SCC in a nitrite-containing chloride solution. Slow strain rate testing (SSRT in 30 wt. % MgCl2 solution established SCC susceptibility, as evidenced by post-SSRT fractography. Addition of nitrite to the chloride solution, which is reported to have inhibitive influence on corrosion of stainless steels, was found to increase SCC susceptibility. The susceptibility was also found to increase with nitrite concentration. This behaviour is explained on the basis of the passivation and pitting characteristics of 316L steel in chloride solution.

  12. A carbon nanotube/polyvanillin composite film as an electrocatalyst for the electrochemical oxidation of nitrite and its application as a nitrite sensor

    Energy Technology Data Exchange (ETDEWEB)

    Zheng Dongyun [College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072 (China); State Key Laboratory of Transducer Technology, Chinese Academy of Sciences (China); Hu Chengguo [College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072 (China); State Key Laboratory of Transducer Technology, Chinese Academy of Sciences (China)], E-mail: cghu@whu.edu.cn; Peng Yanfen [College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072 (China); State Key Laboratory of Transducer Technology, Chinese Academy of Sciences (China); Hu Shengshui [College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072 (China); State Key Laboratory of Transducer Technology, Chinese Academy of Sciences (China)], E-mail: sshu@whu.edu.cn

    2009-08-30

    We report a simple method for the stable dispersion of multi-walled carbon nanotubes (MWNTs) in water by vanillin and controllable surface addition onto carbon fiber microelectrodes (CFE) via electropolymerization. We have characterized these polyvanillin-carbon nanotube (PVN-MWNT) composite films with techniques including scanning electron microscopy (SEM), infrared spectroscopy (IR) and voltammetry. These investigations showed that the films have a uniform porous nanostructure with a large surface area. This PVN-MWNT composite-modified CFE (PVN-MWNT/CFE) exhibited a sensitive response to the electrochemical oxidation of nitrite. Under optimal working conditions, the oxidation peak current of nitrite linearly increased with its concentration in the range of 0.2 {mu}M-3.1 mM, with the system exhibiting a lower detection limit of 50 nM (S/N = 3). We successfully applied the PVN-MWNT/CFE system to the determination of nitrite from lake water. The efficient recovery of nitrite indicated that this electrode was able to detect nitrite in real samples.

  13. Shewanella oneidensis cytochrome c nitrite reductase (ccNiR) does not disproportionate hydroxylamine to ammonia and nitrite, despite a strongly favorable driving force.

    Science.gov (United States)

    Youngblut, Matthew; Pauly, Daniel J; Stein, Natalia; Walters, Daniel; Conrad, John A; Moran, Graham R; Bennett, Brian; Pacheco, A Andrew

    2014-04-08

    Cytochrome c nitrite reductase (ccNiR) from Shewanella oneidensis, which catalyzes the six-electron reduction of nitrite to ammonia in vivo, was shown to oxidize hydroxylamine in the presence of large quantities of this substrate, yielding nitrite as the sole free nitrogenous product. UV-visible stopped-flow and rapid-freeze-quench electron paramagnetic resonance data, along with product analysis, showed that the equilibrium between hydroxylamine and nitrite is fairly rapidly established in the presence of high initial concentrations of hydroxylamine, despite said equilibrium lying far to the left. By contrast, reduction of hydroxylamine to ammonia did not occur, even though disproportionation of hydroxylamine to yield both nitrite and ammonia is strongly thermodynamically favored. This suggests a kinetic barrier to the ccNiR-catalyzed reduction of hydroxylamine to ammonia. A mechanism for hydroxylamine reduction is proposed in which the hydroxide group is first protonated and released as water, leaving what is formally an NH2(+) moiety bound at the heme active site. This species could be a metastable intermediate or a transition state but in either case would exist only if it were stabilized by the donation of electrons from the ccNiR heme pool into the empty nitrogen p orbital. In this scenario, ccNiR does not catalyze disproportionation because the electron-donating hydroxylamine does not poise the enzyme at a sufficiently low potential to stabilize the putative dehydrated hydroxylamine; presumably, a stronger reductant is required for this.

  14. Acute, Sub-lethal Cyanide Poisoning in Mice is Ameliorated by Nitrite Alone: Complications Arising from Concomitant Administration of Nitrite and Thiosulfate as an Antidotal Combination

    Science.gov (United States)

    Cambal, Leah K.; Swanson, Megan R.; Yuan, Quan; Weitz, Andrew C.; Li, Hui-Hua; Pitt, Bruce R.; Pearce, Linda L.; Peterson, Jim

    2011-01-01

    Sodium nitrite alone is shown to ameliorate sub-lethal cyanide toxicity in mice when given from ~1 hour before until 20 minutes after the toxic dose as demonstrated by the recovery of righting ability. An optimum dose (12 mg/kg) was determined to significantly relieve cyanide toxicity (5.0 mg/kg) when administered to mice intraperitoneally. Nitrite so administered was shown to rapidly produce NO in the bloodsteam as judged by the dose dependent appearance of EPR signals attributable to nitrosylhemoglobin and methemoglobin. It is argued that antagonism of cyanide inhibition of cytochrome c oxidase by NO is the crucial antidotal activity rather than the methemoglobin-forming action of nitrite. Concomitant addition of sodium thiosulfate to nitrite-treated blood resulted in the detection of sulfidomethemoblobin by EPR spectroscopy. Sulfide is a product of thiosulfate hydrolysis and, like cyanide, is known to be a potent inhibitor of cytochrome c oxidase; the effects of the two inhibitors being essentially additive under standard assay conditions, rather than dominated by either one. The findings afford a plausible explanation for an observed detrimental effect in mice associated with the use of the standard nitrite-thiosulfate combination therapy at sub-lethal levels of cyanide intoxication. PMID:21534623

  15. Combined effects of high hydrostatic pressure and sodium nitrite on color, water holding capacity and texture of frankfurter

    Science.gov (United States)

    Jonas, G.; Csehi, B.; Palotas, P.; Toth, A.; Kenesei, Gy; Pasztor-Huszar, K.; Friedrich, L.

    2017-10-01

    The aim of this study was to investigate the effect of sodium nitrite and high hydrostatic pressure on the color, water holding capacity (WHC) and texture characteristics of frankfurter. Three hundred, 450 and 600 MPa (5 minutes; 20 °C) and 50, 75, 100 and 125 ppm (calculated on weight of meat) sodium nitrite were applied. Parameters were measured right after the pressure treatment. Data were evaluated with two-way analysis of variance (p 0.05) with pressure levels and sodium nitrite amounts as factors. Nitrite reduction significantly increased lightness (L*) and resulted in decreased redness (a*) value. The pressure treatments decreased the lightness at all nitrite concentrations and did not significantly affect the red color of frankfurters. Fifty and 75 ppm nitrite and pressurization at 300 or 450 MPa improved the water holding property of frankfurter. The pressure treatment did not significantly affect the WHC but changing the nitrite amount had significant effect on it. Interactive effect occurred between pressure levels and nitrite concentrations for hardness. The pressure treatment increased and the nitrite reduction decreased hardness. Significant changes were found in cohesiveness at 450 and 600 MPa in frankfurters containing 50 and 75 ppm nitrite: pressure treatment at higher levels and nitrite reduction decreased the value of cohesiveness.

  16. The effects of elevated environmental CO2 on nitrite uptake in the air-breathing clown knifefish, Chitala ornata

    DEFF Research Database (Denmark)

    Le Thi Hong Gam; Jensen, Frank Bo; Do Thi Thanh Huong

    2018-01-01

    hypercapnia) and nitrite for 96 h. Blood was sampled to measure acid-base status, haemoglobin derivatives and plasma ions. Plasma nitrite increased for 48 h, but levels stayed below the exposure concentration, and subsequently decreased as a result of nitrite detoxification to nitrate. The total uptake......Nitrite and carbon dioxide are common environmental contaminants in the intensive aquaculture ponds used to farm clown knifefish (Chitala ornata) in the Mekong delta, Vietnam. Here we tested the hypothesis that hypercapnia reduces nitrite uptake across the gills, because pH regulation will reduce...... chloride uptake and hence nitrite uptake as the two ions compete for the same transport route via the branchial HCO3-/Cl- exchanger. Fish fitted with arterial catheters were exposed to normocapnic/normoxic water (control), nitrite (1 mM), hypercapnia (21 mmHg CO2), or combined hypercapnia (acclimated...

  17. The Effect of Influent Characteristics and Operational Conditions over the Performance and Microbial Community Structure of Partial Nitritation Reactors

    Directory of Open Access Journals (Sweden)

    Alejandro Rodriguez-Sanchez

    2014-06-01

    Full Text Available Nitrogen is a main contaminant of wastewater worldwide. Novel processes for nitrogen removal have been developed over the last several decades. One of these is the partial nitritation process. This process includes the oxidation of ammonium to nitrite without the generation of nitrate. The partial nitritation process has several advantages over traditional nitrification-denitrification processes for nitrogen removal from wastewaters. In addition, partial nitritation is required for anammox elimination of nitrogen from wastewater. Partial nitritation is affected by operational conditions and substances present in the influent, such as quinolone antibiotics. In this review, the impact that several operational conditions, such as temperature, pH, dissolved oxygen concentration, hydraulic retention time and solids retention time, have over the partial nitritation process is covered. The effect of quinolone antibiotics and other emerging contaminants are discussed. Finally, future perspectives for the partial nitritation process are commented upon.

  18. DIHYDROPYRIDINE CALCIUM- CHANNELBLOCKERSFOR ...

    African Journals Online (AJOL)

    Furthermore, the controversy over the role of calci~-channel blockers as first-line ..... group trials while fully accounting for placebo effects as well as interindividual ..... Reducing calcium overload in the ischemic brain. N Engl JMed. 1999; 341 ...

  19. Calcium and Your Child

    Science.gov (United States)

    ... calcium-set tofu edamame (soybeans) broccoli, collard greens, kale, chard, Chinese cabbage, and other leafy greens almonds ... more dark green, leafy vegetables (such as broccoli, kale, collard greens, or Chinese cabbage) with meals. Kids ...

  20. Rapid and simple preparation of rhodamine 6G loaded HY zeolite for highly selective nitrite detection

    Science.gov (United States)

    Viboonratanasri, Duangkamon; Pabchanda, Suwat; Prompinit, Panida

    2018-05-01

    In this study, a simple, rapid and relatively less toxic method for rhodamine 6G dye adsorption on hydrogen-form Y-type zeolite for highly selective nitrite detection was demonstrated. The adsorption behavior was described by Langmuir isotherm and the adsorption process reached the equilibrium promptly within a minute. The developed test papers characterized by fluorescence technique display high sensing performance with wide working range (0.04-20.0 mg L-1) and high selectivity. The test papers show good reproducibility with relative standard deviation (RSD) of 7% for five replicated determinations of 3 mg L-1 of nitrite. The nitrite concentration determined by using the test paper was in the same range as using ion chromatography within a 95% confidence level. The test papers offer advantages in terms of low cost and practical usage enabling them to be a promising candidate for nitrite sensor in environmental samples, food, and fertilizers.

  1. The kinetics for ammonium and nitrite oxidation under the effect of hydroxylamine.

    Science.gov (United States)

    Wan, Xinyu; Xiao, Pengying; Zhang, Daijun; Lu, Peili; Yao, Zongbao; He, Qiang

    2016-01-01

    The kinetics for ammonium (NH4(+)) oxidation and nitrite (NO2(-)) oxidation under the effect of hydroxylamine (NH2OH) were studied by respirometry using the nitrifying sludge from a laboratory-scale sequencing batch reactor. Modified models were used to estimate kinetics parameters of ammonia and nitrite oxidation under the effect of hydroxylamine. An inhibition effect of hydroxylamine on the ammonia oxidation was observed under different hydroxylamine concentration levels. The self-inhibition coefficient of hydroxylamine oxidation and noncompetitive inhibition coefficient of hydroxylamine for nitrite oxidation was estimated by simulating exogenous oxygen-uptake rate profiles, respectively. The inhibitive effect of NH2OH on nitrite-oxidizing bacteria was stronger than on ammonia-oxidizing bacteria. This work could provide fundamental data for the kinetic investigation of the nitrification process.

  2. Evaluation of the Intake of Nitrate, Nitrite, Nitrosodiethylamine and Nitrosodimethylamine by Food Consumption

    Directory of Open Access Journals (Sweden)

    Liliana Avasilcai

    2014-12-01

    Full Text Available The aim of the present study was the evaluation of nitrate, nitrite, nitrosodiethylamine (NDEA and nitrosodimethylamine (NDMA intake by food consumption. We determined concentrations of nitrates, nitrites in 102 food samples (40 meat products, 15 fermented cheese, 25 vegetables, 22 fruits and the concentration NDEA, NDMA in 40 meat products. Nitrates and nitrites were determined using Peter-Griess method; nitrosamines were quantified by HPLC with UV detection.  We designed vegetalian, vegetarian and conventional diets of about 2500 kcal/day.  Based of the values found, we calculated the intake of nitrates, nitrites and nitrosamines. The obtained values fits to WHO’s recommendations, except for vegetalian and conventional diet, in which the nitrate content was 3,46 respectively 1,64 times higher than the acceptable daily intake (157 mg NO3-/day.

  3. Nitrite-induced enhancement of toxicity of phenanthrene in fish and its implications for coastal waters

    Digital Repository Service at National Institute of Oceanography (India)

    Shailaja, M.S.; Rodrigues, A

    Coastal areas are prone to varying degrees of anthropogenic chemical contamination. In many coastal environments experiencing reducing conditions in the water column, nitrite is produced as a result of denitrification. With a view to determining...

  4. Increased formation of carcinogenic PAH metabolites in fish promoted by nitrite

    Digital Repository Service at National Institute of Oceanography (India)

    Shailaja, M.S.; Rajamanickam, R.; Wahidullah, S.

    Nitrite (NO2−), a highly reactive chemical species, accumulates in coastal waters as a result of pollution with nitrogenous waste and/or an imbalance in the bacterial processes of nitrification and denitrification. The present study probed...

  5. Bioelectrode-based approach for enhancing nitrate and nitrite removal and electricity generation from eutrophic lakes

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    Nitrate and nitrite contamination of surface waters (e.g. lakes) has become a severe environmental and health problem, especially in developing countries. The recent demonstration of nitrate reduction at the cathode of microbial fuel cell (MFC) provides an opportunity to develop a new technology...... from nitrate- and nitrite-rich synthetic lake waters at initial concentration of 10 mg-N/L. Along with the electricity production a total nitrogen removal of 62% and 77% was accomplished, for nitrate and nitrite, respectively. The nitrogen removal was almost 4 times higher under close-circuit condition...... with biocathode, compared to either the open-circuit operation or with abiotic cathode. The mass balance on nitrogen indicates that most of the removed nitrate and nitrite (84.7±0.1% and 81.8±0.1%, respectively) was reduced to nitrogen gas. The nitrogen removal and power generation was limited by the dissolved...

  6. Nitrite electrochemical sensor based on prussian blue/single-walled carbon nanotubes modified pyrolytic graphite electrode

    CSIR Research Space (South Africa)

    Adekunle, AS

    2011-09-01

    Full Text Available Nitrite, NO2- (in neutral), and NO (in acidic media) were used as analytical probe to investigate the electrocatalytic properties of Prussian blue nanoparticles (PB) modified edge plane pyrolytic graphite (EPPG) electrode. Results indicate...

  7. Dramatic loss of comammox Nitrospira associated with long-term nitrite feeding

    DEFF Research Database (Denmark)

    Kinnunen, Marta; Palomo, Alejandro; Dechesne, Arnaud

    Until recently, nitrification was thought to be a strict two-step process where ammonia was first oxidized to nitrite by ammonia-oxidizing bacteria and/or archaea, and subsequently to nitrate by nitrite oxidizing bacteria (NOB). Recent studies in NOB metabolism, however, have revealed that certain......, with nitrite as the main energy source. Community assembly was monitored on well-established biofilms formed on the grains of rapid sand filter (RSF) for drinking water production. RSF sand was placed in laboratory scale column bioreactors and subjected to continuous feeding of tap water spiked with NO2- (1 mg...... sequences (100% similarity to uncultured Nitrospira sp. clone KC836101 (Pester et al., 2014)). These observations indicate different behavior of Nitrospira in the absence of ammonia and point to a possible competitive advantage of canonical Nitrospira in environments where nitrite is the sole nitrogen...

  8. Irradiation and modified atmosphere packaging effects on residual nitrite, ascorbic acid, nitrosomyoglobin, and color in sausage.

    Science.gov (United States)

    Ahn, Hyun-Joo; Jo, Cheorun; Lee, Ju-Woon; Kim, Jae-Hyun; Kim, Kee-Hyuk; Byun, Myung-Woo

    2003-02-26

    The present study was undertaken to evaluate the irradiation and modified atmosphere packaging effects on emulsion-type cooked pork sausage during storage for 4 weeks. CO(2) (100%), N(2) (100%), or 25% CO(2)/75% N(2) packaged sausage were irradiated at 0, 5, and 10 kGy, and residual nitrite, residual ascorbic acid, nitrosomyoglobin (NO-Mb), color values, and their correlation were observed. Irradiation significantly reduced the residual nitrite content and caused partial reduction of NO-Mb during storage. No difference was observed in ascorbic acid content by irradiation. Irradiation decreased the Hunter color a value of sausage. CO(2) or CO(2)/N(2) packaging were more effective for reducing residual nitrite and inhibiting the loss of the red color of sausage compared to N(2) packaging. Results indicated that the proper combination of irradiation and modified atmosphere packaging could reduce the residual nitrite in sausage with minimization of color change.

  9. Nitrite Biosensing via Selective Enzymes—A Long but Promising Route

    Directory of Open Access Journals (Sweden)

    M. Gabriela Almeida

    2010-12-01

    Full Text Available The last decades have witnessed a steady increase of the social and political awareness for the need of monitoring and controlling environmental and industrial processes. In the case of nitrite ion, due to its potential toxicity for human health, the European Union has recently implemented a number of rules to restrict its level in drinking waters and food products. Although several analytical protocols have been proposed for nitrite quantification, none of them enable a reliable and quick analysis of complex samples. An alternative approach relies on the construction of biosensing devices using stable enzymes, with both high activity and specificity for nitrite. In this paper we review the current state-of-the-art in the field of electrochemical and optical biosensors using nitrite reducing enzymes as biorecognition elements and discuss the opportunities and challenges in this emerging market.

  10. Changes of sodium nitrate, nitrite, and N-nitrosodiethylamine during in vitro human digestion.

    Science.gov (United States)

    Kim, Hyeong Sang; Hur, Sun Jin

    2017-06-15

    This study aimed to determine the changes in sodium nitrate, sodium nitrite, and N-nitrosodiethylamine (NDEA) during in vitro human digestion, and the effect of enterobacteria on the changes in these compounds. The concentrations of nitrate, nitrite, and NDEA were significantly reduced from 150, 150, and 1ppm to 42.8, 63.2, and 0.85ppm, respectively, during in vitro human digestion (pdigestion. This study is the first to report that E. coli can dramatically reduce the amount of nitrite during in vitro human digestion and this may be due to the effect of nitrite reductase present in E. coli. We therefore conclude that the amounts of potentially harmful substances and their toxicity can be decreased during human digestion. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Determination of nitrite ion at schiff's base derivative of chitosan modified glassy carbon electrode

    International Nuclear Information System (INIS)

    Xu Zhongliang; Zhang Jianmei; Liu Shujuan; Peng Daofeng

    2007-01-01

    Chitosan react with salicyclaldehyde by schiff's base reaction in water, a polymer product S-CTS can be prepared. Glassy carbon electrode was modified with S-CTS by drop-coating method. Then, its electrocatalysis effect on the reduction of nitrite by the films of S-CTS was investigated. Experimental results showed that S-CTS modified electrode could reduce the oxidation overpotential of nitrite in pH4.5 B-R buffer solution, the peak current of reduction was proportional to the concentration of nitrite and a good linear relation from 0.20 to 81 mg/kg (r=0.9899) with a detection limit of 2.8 x 10 -7 mol/L was obtained. The methods have been applied to determining nitrite in some samples, satisfactory results were obtained. (authors)

  12. Calcium binding by dietary fibre

    International Nuclear Information System (INIS)

    James, W.P.T.; Branch, W.J.; Southgate, D.A.T.

    1978-01-01

    Dietary fibre from plants low in phytate bound calcium in proportion to its uronic-acid content. This binding by the non-cellulosic fraction of fibre reduces the availability of calcium for small-intestinal absorption, but the colonic microbial digestion of uronic acids liberates the calcium. Thus the ability to maintain calcium balance on high-fibre diets may depend on the adaptive capacity on the colon for calcium. (author)

  13. A model of propagating calcium-induced calcium release mediated by calcium diffusion

    NARCIS (Netherlands)

    Backx, P. H.; de Tombe, P. P.; van Deen, J. H.; Mulder, B. J.; ter Keurs, H. E.

    1989-01-01

    The effect of sudden local fluctuations of the free sarcoplasmic [Ca++]i in cardiac cells on calcium release and calcium uptake by the sarcoplasmic reticulum (SR) was calculated with the aid of a simplified model of SR calcium handling. The model was used to evaluate whether propagation of calcium

  14. [Calcium suppletion for patients who use gastric acid inhibitors: calcium citrate or calcium carbonate?].

    NARCIS (Netherlands)

    Jonge, H.J. de; Gans, R.O.; Huls, G.A.

    2012-01-01

    Various calcium supplements are available for patients who have an indication for calcium suppletion. American guidelines and UpToDate recommend prescribing calcium citrate to patients who use antacids The rationale for this advice is that water-insoluble calcium carbonate needs acid for adequate

  15. Color compensation in nitrite-reduced meat batters incorporating paprika or tomato paste.

    Science.gov (United States)

    Bázan-Lugo, Eduardo; García-Martínez, Ignacio; Alfaro-Rodríguez, Rosa Hayde; Totosaus, Alfonso

    2012-06-01

    Nitrite is a key ingredient the manufacture of meat products, forming a stable pink color characteristic of cured products, retarding the development of rancidity and off-odors and flavors during storage, and preventing microbial growth. The negative aspects of nitrite and the demands for healthy foods result in the need to reduce nitrite in cured meat products. Paprika or tomato has been employed as natural pigments in meat products. The objective of this work was to determine the effect of incorporating paprika powder or tomato paste on the texture, rancidity and instrumental and sensory color compensation in nitrite-reduced meat batters. Addition of tomato paste improved moisture content, resulting in harder but less cohesive samples as compared to control and paprika-containing meat batters. Color characteristics of reduced nitrite samples obtained higher a* red coloration (8.9 for paprika and 7.7-8.0 for tomato paste), as compared to control samples (5.65). Instrumental color was low in control samples, with high values for tomato paste and paprika samples. Nonetheless, tomato paste used to compensate color in nitrite-reduced meat batters was ranked closer to the control sample in sensory evaluation. Color characteristics-instrumental and sensory-in these kinds of meat products were enhanced by the addition of 2.5-3.0% of tomato paste, presenting results close to the non-reduced nitrite control. Similarly, antioxidant components of tomato paste or paprika reduced lipid oxidation. Nitrite reduction from 150 to 100 ppm could be achieved employing tomato paste as a natural pigment to improve color and texture. Copyright © 2011 Society of Chemical Industry.

  16. Histopathological effects of sodium nitrite on the spleen of male and female rats

    Directory of Open Access Journals (Sweden)

    Fateme Juibar

    2015-01-01

    Full Text Available Background: Nitrite and nitrate are common additives in meat processed products. In spite of all technological advantages of nitrite, creation of nitrosamine carcinogenic substances causes a lot of concerns for use of these additives. In this study, the histopatological effects of sodium nitrite on the splenic tissue in adult male and female rats were evaluated. Material and method: In recent studies, 60 adult male and female rats strain Vistar, divided in 6 groups of 10. They were examined for 60 day, and they (male and female rats separately were divided in 175 mg/kg/day dose recipient group, 350 mg/kg/day dose recipient group and control group which was absorbed nitrite through drinking water. At the end of day 60, using cotton dipped in ether in the jar of anesthesia, were anesthetized. After anesthesia, blood from the left ventricle was taken .the spleen was taking out of body, and then tissue sections were prepared for testing tissue changes. The samples were stained with Hematoxilin- Eozin method. In both sex, factors like morphometric and morphologic from spleen tissue, body weight changes before and after test and blood NOx level was checked. After data collection, all data was analyzed by SPSS statistical software version 17 with using Independent sample t-test and ANOVA. P value of less than 0.05 were reported as statistically significant. Result: The results showed that consume of sodium nitrite, cause background inflammation type of Mononuclear in both sex, especially around the pulp. Also, in both sex NOx levels in the blood of animals in the group receiving 350 mg/ kg and group receiving 175 mg of sodium nitrite per kg compared with the control group, significantly increased (p ≤ 0.05. Conclusion: Considering of this study and other studies, Nitrite can cause damage to blood vessels, liver, spleen and other organs. Also sodium nitrite has to switching to other food preservatives.

  17. Nitrite oxidation kinetics of two Nitrospira strains: The quest for competition and ecological niche differentiation.

    Science.gov (United States)

    Ushiki, Norisuke; Jinno, Masaru; Fujitani, Hirotsugu; Suenaga, Toshikazu; Terada, Akihiko; Tsuneda, Satoshi

    2017-05-01

    Nitrite oxidation is an aerobic process of the nitrogen cycle in natural ecosystems, and is performed by nitrite-oxidizing bacteria (NOB). Also, nitrite oxidation is a rate-limiting step of nitrogen removal in wastewater treatment plants (WWTPs). Although Nitrospira is known as dominant NOB in WWTPs, information on their physiological properties and kinetic parameters is limited. Here, we report the kinetic parameters and inhibition of nitrite oxidation by free ammonia in pure cultures of Nitrospira sp. strain ND1 and Nitrospira japonica strain NJ1, which were previously isolated from activated sludge in a WWTP. The maximum nitrite uptake rate ( [Formula: see text] ) and the half-saturation constant for nitrite uptake ( [Formula: see text] ) of strains ND1 and NJ1 were 45 ± 7 and 31 ± 5 (μmol NO 2 - /mg protein/h), and 6 ± 1 and 10 ± 2 (μM NO 2 - ), respectively. The [Formula: see text] and [Formula: see text] of two strains indicated that they adapt to low-nitrite-concentration environments like activated sludge. The half-saturation constants for oxygen uptake ( [Formula: see text] ) of the two strains were 4.0±2.5 and 2.6±1.1 (μM O 2 ), respectively. The [Formula: see text] values of the two strains were lower than those of other NOB, suggesting that Nitrospira in activated sludge could oxidize nitrite in the hypoxic environments often found in the interiors of biofilms and flocs. The inhibition thresholds of the two strains by free ammonia were 0.85 and 4.3 (mg-NH 3 l -1 ), respectively. Comparing the physiological properties of the two strains, we suggest that tolerance for free ammonia determines competition and partitioning into ecological niches among Nitrospira populations. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  18. Some observations concerning the direct titration of nitrite with cerium(IV)

    International Nuclear Information System (INIS)

    Muralikrishna, U.; Subrahmanyam, K.; Suryanarayana, M.V.S.; Krishnamurthy, M.

    1983-01-01

    Direct titration of nitrite with cerium(IV), with ferroin as indicator, is shown to give satisfactory results if the acidity is kept between 0.033 and 0.055 M at the end-point. Loss of nitrous acid owing to volatilization and decomposition is discussed. From 10 to 60 mg of sodium nitrite can be estimated with a standard deviation of 5 μg and an average error of 0.2%. (author)

  19. Protection of Steel Corrosion in Concrete Members by the Combination of Galvanic Anode and Nitrite Penetration

    Directory of Open Access Journals (Sweden)

    Minobu Aoyama

    2014-01-01

    Full Text Available Chloride induced-corrosion of steel bars in concrete can make cracks and exfoliation in near-surface regions in reinforced concrete structures. In this paper, we described the basic concept and practice of steel bars corrosion protection method by the combination of galvanic anode (zinc wire and the penetration of nitrite ions from mortar layers containing a large amount of lithium nitrite.

  20. [Poppers at top: alkyl nitrites use in France].

    Science.gov (United States)

    Beck, François; Guignard, Romain; Richard, Jean-Baptiste

    2014-10-01

    Poppers is the usual name of various forms of alkyl nitrites. They are used as recreational drugs to intensify sexual intercourses and provoke a short euphoria just after their inhalation. In spite of several periods of ban in the 2000s, poppers' use sharply rose between 2000 and 2010. In the adult population as in teenagers, it is the second product consumed after cannabis among illicit drugs, confirming that it concerns circles wider than gays and lesbians who are sometimes depicted as emblematic users. The lifetime use of poppers concerns 5.3% of 18-64 years in 2010, men (7.2%) more than women (3.4%). At the end of the adolescence, its lifetime prevalence is 8.8% for girls and 9.2% for boys. In the general population and especially among young people, poppers is favourably considered. Nevertheless, this product is not without danger, even if the risk of dependence is extremely low. Several avenues of interventions may be outlined, mainly based on information and a regular follow-up of users which can allow to avoid an intensification of the consumption. © 2014 médecine/sciences – Inserm.

  1. ASPECTS CONCERNING NITRATE AND NITRITE POLLUTION OF GROUNDWATERS

    Directory of Open Access Journals (Sweden)

    A. UNGUREANU

    2011-03-01

    Full Text Available Aspects concerning nitrate and nitrite pollution of groundwaters. Water is a basic natural resource for the good functioning of all thebiological processes in nature. It is very important for life and for the developmentof human activities. The quality of the ground water has begun to degrade moreand more, as a result of the physical, chemical and bacteriological changes.Nitrogen compounds pollution of the underground has increased lately. This hasbeen caused by the excessive and irrational use of nitrogen derived fertilizers, bythe wrong storage of the dejections resulted from zootechnical processes and byother chemical substances discharged into water. Samples were collected fromdifferent wells in order to check whether the well water was drinkable. The resultof the test revealed the existence of high concentrations of nitrates as well asvalues exceeding normal microbiological parameters. The value recorded in thetown of Segarcea, the county of Dolj, showed extremely high concentrations ofnitrates of the drinking water in the wells. Thus, Segarcea is the town with thegreatest number of contaminated wells in the country.

  2. Removal of nitrite impurity from nitrate labeled with nitrogen-15

    International Nuclear Information System (INIS)

    Malone, J.P.; Stevens, R.J.

    1998-01-01

    Potassium nitrate labeled with 15 N is often used as a tracer in studies of N dynamics in soil and water systems. Typically, 0.8% NO 2 - impurity has been found in the batches of K 15 NO 3 enriched to 99 atom % excess 15 N that were purchased by our laboratory. Nitrite is an intermediate in several N cycling processes so its addition when adding NO 3 - could produce misleading results. We have developed a safe, simple, and inexpensive method to remove NO 2 - impurity from any NO 3 - solution in a water matrix. The principle is the oxidation of NO2- to NO 3 - by UV light in the presence of a heterogenous TiO 2 catalyst. A NO 2 - concentration of 0.2 mM in 100 mL of 0.2 M NO 3 - solution could be oxidized in 12 min using 0.5 g L -1 TiO 2 in a specially constructed photoreactor with a 75-W UV facial tanning lamp. For the routine removal of NO 2 - , use of the same TiO 2 concentration in a standard beaker worked equally well when the irradiation time was extended to 2.5 h. After irradiation, the TiO2 is easily and totally removed from the solution by membrane filtration. (author)

  3. Calcium in plant cells

    Directory of Open Access Journals (Sweden)

    V. V. Schwartau

    2014-04-01

    Full Text Available The paper gives the review on the role of calcium in many physiological processes of plant organisms, including growth and development, protection from pathogenic influences, response to changing environmental factors, and many other aspects of plant physiology. Initial intake of calcium ions is carried out by Ca2+-channels of plasma membrane and they are further transported by the xylem owing to auxins’ attractive ability. The level of intake and selectivity of calcium transport to ove-ground parts of the plant is controlled by a symplast. Ca2+enters to the cytoplasm of endoderm cells through calcium channels on the cortical side of Kaspary bands, and is redistributed inside the stele by the symplast, with the use of Ca2+-АТPases and Ca2+/Н+-antiports. Owing to regulated expression and activity of these calcium transporters, calclum can be selectively delivered to the xylem. Important role in supporting calcium homeostasis is given to the vacuole which is the largest depo of calcium. Regulated quantity of calcium movement through the tonoplast is provided by a number of potential-, ligand-gated active transporters and channels, like Ca2+-ATPase and Ca2+/H+ exchanger. They are actively involved in the inactivation of the calcium signal by pumping Ca2+ to the depo of cells. Calcium ATPases are high affinity pumps that efficiently transfer calcium ions against the concentration gradient in their presence in the solution in nanomolar concentrations. Calcium exchangers are low affinity, high capacity Ca2+ transporters that are effectively transporting calcium after raising its concentration in the cell cytosol through the use of protons gradients. Maintaining constant concentration and participation in the response to stimuli of different types also involves EPR, plastids, mitochondria, and cell wall. Calcium binding proteins contain several conserved sequences that provide sensitivity to changes in the concentration of Ca2+ and when you

  4. Enhanced Activity and Selectivity of Carbon Nanofiber Supported Pd Catalysts for Nitrite Reduction

    KAUST Repository

    Shuai, Danmeng; Choe, Jong Kwon; Shapley, John R.; Werth, Charles J.

    2012-01-01

    Pd-based catalyst treatment represents an emerging technology that shows promise to remove nitrate and nitrite from drinking water. In this work we use vapor-grown carbon nanofiber (CNF) supports in order to explore the effects of Pd nanoparticle size and interior versus exterior loading on nitrite reduction activity and selectivity (i.e., dinitrogen over ammonia production). Results show that nitrite reduction activity increases by 3.1-fold and selectivity decreases by 8.0-fold, with decreasing Pd nanoparticle size from 1.4 to 9.6 nm. Both activity and selectivity are not significantly influenced by Pd interior versus exterior CNF loading. Consequently, turnover frequencies (TOFs) among all CNF catalysts are similar, suggesting nitrite reduction is not sensitive to Pd location on CNFs nor Pd structure. CNF-based catalysts compare favorably to conventional Pd catalysts (i.e., Pd on activated carbon or alumina) with respect to nitrite reduction activity and selectivity, and they maintain activity over multiple reduction cycles. Hence, our results suggest new insights that an optimum Pd nanoparticle size on CNFs balances faster kinetics with lower ammonia production, that catalysts can be tailored at the nanoscale to improve catalytic performance for nitrite, and that CNFs hold promise as highly effective catalyst supports in drinking water treatment. © 2012 American Chemical Society.

  5. Role of nitrite, urate and pepsin in the gastroprotective effects of saliva

    Science.gov (United States)

    Rocha, Bárbara S.; Lundberg, Jon O; Radi, Rafael; Laranjinha, João

    2016-01-01

    Dietary nitrate is now recognized as an alternative substrate for nitric oxide (•NO) production in the gut. This novel pathway implies the sequential reduction of nitrate to nitrite, •NO and other bioactive nitrogen oxides but the physiological relevance of these oxidants has remained elusive. We have previously shown that dietary nitrite fuels an hitherto unrecognized nitrating pathway at acidic gastric pH, through which pepsinogen is nitrated in the gastric mucosa, yielding a less active form of pepsin in vitro. Here, we demonstrate that pepsin is nitrated in vivo and explore the functional impact of protein nitration by means of peptic ulcer development. Upon administration of pentagastrin and human nitrite-rich saliva or sodium nitrite to rats, nitrated pepsin was detected in the animal's stomach by immunoprecipitation. •NO was measured in the gastric headspace before and after nitrite instillation by chemiluminescence. At the end of each procedure, the stomach's lesions, ranging from gastric erosions to haemorrhagic ulcers, were scored. Nitrite increased gastric •NO by 200-fold (pstomach, preventing the progression of gastric ulcers. PMID:27156250

  6. A family cluster of nitrite poisoning, Suzhou City, Jiangsu Province, China, 2013

    Directory of Open Access Journals (Sweden)

    Ruiping Wang

    2013-07-01

    Full Text Available Background: In April 2013, a hospital in Suzhou City notified authorities of a patient with nitrite poisoning with two other family members who had similar toxic symptoms five days prior. We investigated the event to identify the cause, source and possible route of contamination. Methods: A case was defined as any person living in the Yang Shan Hua Yuan community who had been diagnosed with cyanoderma and food poisoning symptoms from 15 to 25 April 2013. Active case finding was conducted by interviewing community residents and reviewing medical records from local clinics; information was then retrospectively collected on the patient’s food history, cooking procedures and food sources. Results: We identified three nitrite poisoning cases, one male and two females, from the same family. The time between dinner and onset of illness was less than an a hour. A retrospective survey showed that a substance presumed to be sugar mixed with asparagus on 17 April and with stir-fried asparagus on 21 April wasthe suspected contaminant. The presumed sugar came from a clean-up of a neighbouring rental house. Nitrite was detected in a vomitus sample, the sugar substance and two leftover food samples. Conclusion: This family cluster of nitrite poisoning resulted from the mistaken use of nitrite as sugar to cook dishes. We recommend that sodium nitrite be dyed a bright colour to prevent such a mistake and that health departments strengthen food hygiene education to alert people about the danger of eating unidentified food from an unknown source.

  7. The impairment of learning and memory and synaptic loss in mouse after chronic nitrite exposure.

    Science.gov (United States)

    Chen, Yongfang; Cui, Zhanjun; Wang, Lai; Liu, Hongliang; Fan, Wenjuan; Deng, Jinbo; Deng, Jiexin

    2016-12-01

    The objective of this study is to understand the impairment of learning and memory in mouse after chronic nitrite exposure. The animal model of nitrite exposure in mouse was created with the daily intubation of nitrite in adult healthy male mice for 3 months. Furthermore, the mouse's learning and memory abilities were tested with Morris water maze, and the expression of Synaptophysin and γ-Synuclein was visualized with immunocytochemistry and Western blot. Our results showed that nitrite exposure significantly prolonged the escape latency period (ELP) and decreased the values of the frequency across platform (FAP) as well as the accumulative time in target quadrant (ATITQ) compared to control, in dose-dependent manner. In addition, after nitrite exposure, synaptophysin (SYN) positive buttons in the visual cortex was reduced, in contrast the increase of γ-synuclein positive cells. The results above were supported by Western blot as well. We conclude that nitrite exposure could lead to a decline in mice's learning and memory. The overexpression of γ-synuclein contributed to the synaptic loss, which is most likely the cause of learning and memory impairment. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1720-1730, 2016. © 2015 Wiley Periodicals, Inc.

  8. A Family Clustered Nitrite Intoxication Investigation in Gaoxin District, Suzhou, China, 2013.

    Science.gov (United States)

    Wang, Ruiping; Teng, Chengang; Zhang, Ning; Zhang, Jun; Conway, George

    2013-12-01

    In April, 2013, a Suzhou Hospital reported a nitrite intoxication patient in coma as well as 2 family members with the similar symptom 5 days ahead. We investigated the event to identify the cause, source and possible pollution ways of the contamination. We defined case as any person living in YSHY community who has cyanosis and with at least one of the following symptoms: dizziness, headache, fatigue, tachycardia, drowsiness, nausea, vomiting, abdominal pain or diar-rhea during April 15 to April 25, 2013. We searched for case by interviewing community residents and reviewing clinics' medical records; information was then retrospectively collected on the patient's food history, cooking procedures and food sources. We identified 3 nitrite intoxication cases, 1 male and 2 female from a family. The interval time between dinner and onset was mix asparagus' on April 17 and 'scrambled asparagus' on April 21 were suspected foods. Both suspected dishes had 'sugar' added, sourced from a clean-up of a neighboring rental house. Nitrite was detected in a vomitus sample, the 'sugar' and two leftover food samples. This family clustered nitrite intoxication was induced by using unidentified nitrite as sugar to cook dishes. We recommend sodium nitrite should be dyed with bright colors to avoid mistaking it for plain salt or sugar, health departments strengthen food hygiene propaganda to improve people's recognition of food safety, and to alert them the dangerous of eating unidentified or unknown source food.

  9. Detection of nitrite based on fluorescent carbon dots by the hydrothermal method with folic acid

    Science.gov (United States)

    Lin, Haitao; Ding, Liyun; Zhang, Bingyu; Huang, Jun

    2018-05-01

    A fluorescent carbon dots probe for the detection of aqueous nitrite was fabricated by a one-pot hydrothermal method, and the transmission electron microscope, X-ray diffractometer, UV-Vis absorption spectrometer and fluorescence spectrophotometer were used to study the property of carbon dots. The fluorescent property of carbon dots influenced by the concentration of aqueous nitrite was studied. The interaction between the electron-donating functional groups and the electron-accepting nitrous acid could account for the quenching effect on carbon dots by adding aqueous nitrite. The products of the hydrolysis of aqueous nitrite performed a stronger quenching effect at lower pH. The relationship between the relative fluorescence intensity of carbon dots and the concentration of nitrite was described by the Stern-Volmer equation (I0/I - 1 = 0.046[Q]) with a fine linearity (R2 = 0.99). The carbon dots-based probe provides a convenient method for the detection of nitrite concentration.

  10. Electrocatalytic reduction of nitrite using ferricyanide; Application for its simple and selective determination

    International Nuclear Information System (INIS)

    Ojani, Reza; Raoof, Jahan-Bakhsh; Zarei, Ebrahim

    2006-01-01

    The electrocatalytic reduction of nitrite has been studied by ferricyanide at the surface of carbon paste electrode. Cyclic voltammetry and chronoamperometry techniques were used to investigate the suitability of ferricyanide as a mediator for the electrocatalytic nitrite reduction in aqueous solution with various pH. Results showed that pH 0.00 is the most suitable for this purpose. In the optimum pH, the electrocatalytic ability about 700 mV can be seen and the homogeneous second-order rate constant (k s ) for nitrite coupled catalytically to ferricyanide was calculated 2.75 x 10 3 M -1 s -1 by Nicholson-Shain method. Also, electron transfer coefficients (α) for ferricyanide was determined by using various electrochemical approaches such as Tafel plot in the absence and presence of nitrite 0.556 and 0.760, respectively. The catalytic reduction peak current was linearly dependent on the nitrite concentration and the linearity range obtained was 5.00 x 10 -5 to 1.00 x 10 -3 M. Detection limit has been found to be 2.63 x 10 -5 M (2σ). This method has been applied as a selective, simple and precise method for determination of nitrite in real sample

  11. [Evaluation of nitrites and nitrates food intake in the students' group].

    Science.gov (United States)

    Wawrzyniak, Agata; Hamułka, Jadwiga; Pankowska, Iwona

    2010-01-01

    The aim of study was to determine the intake of nitrites and nitrates in daily food rations of the students' group in 2008 using 3-day dietary food records method and literature mean values of nitrates and nitrites in food products. Intakes of these compounds were calculated and compared to acceptable daily intake (ADI). The average intake of nitrites was 1.7 mg NaNO2/per person/day (28.0% of ADI), nitrates 77.3 mg NaNO3/per person/day that means 25.4% of ADI. The largest nitrites food intake was noticed for meat products supplied 56.5% of nitrites and cereals (20%). Whereas vegetables and their products supplied 76.1% of nitrates: potatoes 17.1%, cabbage 15.5%, beetroots 13.7%. Calculated nitrites intake for men was 2.4 higher than for women. There were no significant differences of nitrates intake between men and women groups.

  12. Energetic Consequences of nitrite stress in Desulfovibrio vulgarisHildenborough, inferred from global transcriptional analysis

    Energy Technology Data Exchange (ETDEWEB)

    He, Qiang; Huang, Katherine H.; He, Zhili; Alm, Eric J.; Fields,Matthew W.; Hazen, Terry C.; Arkin, Adam P.; Wall, Judy D.; Zhou, Jizhong

    2005-11-03

    Many of the proteins that are candidates for bioenergetic pathways involved with sulfate respiration in Desulfovibrio spp. have been studied, but complete pathways and overall cell physiology remain to be resolved for many environmentally relevant conditions. In order to understand the metabolism of these microorganisms under adverse environmental conditions for improved bioremediation efforts, Desulfovibrio vulgaris Hildenborough was used as a model organism to study stress response to nitrite, an important intermediate in the nitrogen cycle. Previous physiological studies demonstrated that growth was inhibited by nitrite and that nitrite reduction was observed to be the primary mechanism of detoxification. Global transcriptional profiling with whole-genome microarrays revealed coordinated cascades of responses to nitrite in pathways of energy metabolism, nitrogen metabolism, oxidative stress response, and iron homeostasis. In agreement with previous observations, nitrite-stressed cells showed a decrease in the expression of genes encoding sulfate reduction functions in addition to respiratory oxidative phosphorylation and ATP synthase activity. Consequently, the stressed cells had decreased expression of the genes encoding ATP-dependent amino acid transporters and proteins involved in translation. Other genes up-regulated in response to nitrite include the genes in the Fur regulon, which is suggested to be involved in iron homeostasis, and genes in the Per regulon, which is predicted to be responsible for oxidative stress response.

  13. Association between dietary nitrate and nitrite intake and sitespecific cancer risk: evidence from observational studies.

    Science.gov (United States)

    Xie, Li; Mo, Miao; Jia, Hui-Xun; Liang, Fei; Yuan, Jing; Zhu, Ji

    2016-08-30

    Epidemiological studies have reported inconsistent findings on the association between dietary nitrate and nitrite intake and cancer risk. We performed a meta-analysis of epidemiological studies to summarize available evidence on the association between dietary nitrate and nitrite intake and cancer risk from published prospective and case-control studies. PubMed database was searched to identify eligible publications through April 30th, 2016. Study-specific relative risks (RRs) with corresponding 95% confidence interval (CI) from individual studies were pooled by using random- or fixed- model, and heterogeneity and publication bias analyses were conducted. Data from 62 observational studies, 49 studies for nitrates and 51 studies for nitrites, including a total of 60,627 cancer cases were analyzed. Comparing the highest vs. lowest levels, dietary nitrate intake was inversely associated with gastric cancer risk (RR = 0.78; 95%CI = 0.67-0.91) with moderate heterogeneity (I2 = 42.3%). In contrast, dietary nitrite intake was positively associated with adult glioma and thyroid cancer risk with pooled RR of 1.21 (95%CI = 1.03-1.42) and 1.52 (95%CI = 1.12-2.05), respectively. No significant associations were found between dietary nitrate/nitrite and cancers of the breast, bladder, colorectal, esophagus, renal cell, non-Hodgkin lymphoma, ovarian, and pancreas. The present meta-analysis provided modest evidence that positive associations of dietary nitrate and negative associations of dietary nitrite with certain cancers.

  14. Nisin: a possible alternative or adjunct to nitrite in the preservation of meats.

    Science.gov (United States)

    Rayman, M K; Aris, B; Hurst, A

    1981-01-01

    Nisin at 75 ppm (75 microgram/g) was superior to 150 ppm of nitrite in inhibiting outgrowth of Clostridium sporogenes PA3679 spores in meat slurries, which had been heated to simulate the process used for cooked ham. The inhibitory activity of nisin decreased as the spore load or pH of the slurries increased. Unlike nitrite, inhibition by nisin was unaffected by high levels of iron either as a constituent of meats or when added as an iron salt. In slurries treated with 75 ppm of nisin, refrigerated storage for 56 days resulted in depletion of nisin to a level low enough to allow outgrowth within 3 to 10 days if the slurries were subsequently abused at 35 degrees C. In contrast, a combination of 40 ppm of nitrite and either 75 or 100 ppm of nisin almost completely inhibited outgrowth in these slurries. The nisin-nitrite combination appeared to have a synergistic effect, and the low concentration of nitrite was sufficient to preserve the color in meats similar to that of products cured with 150 ppm of nitrite. PMID:7195188

  15. [Detection of nitrite and nitrosocompounds in chemical systems and biological liquids by the calorimetric method].

    Science.gov (United States)

    Titov, V Iu; Petrenko, Iu M; Vanin, A F; Stepuro, I I

    2010-01-01

    The capacity of nitrite, S-nitrosothiols (RS-NO), dinitrosyl iron complexes (DNICs) with thiol-containing ligands, and nitrosoamines to inhibit catalase has been used for the selective determination of these compounds in purely chemical systems and biological liquids: cow milk and colostram. The limiting sensitivity of the method is 50 nM. A comparison of the results of the determinations of RS-NO, DNIC, and nitrite by the catalase method and the Greese method conventionally used for nitrite detection showed that, firstly, Greese reagents decompose DNIC and RS-NO to form nitrite. Therefore, the Greese method cannot be used for nitrite determination in solutions of these substances. Secondly, Greese reagents interact with complexes of mercury ions with RS-NO, inducing the release of nitrosonium ions from the complex followed by the hydrolysis of nitrosonium to nitrite. Thus, the proposition about the spontaneous decay of the complexes of mercury ions with RS-NO is incorrect. Keeping in mind a high sensitivity of the method, the use of catalase as an enzyme detector of nitrosocompounds allows one to detect these compounds in neutral medium without prior purification of the object, thereby preventing artificial effects due to noncontrolled modifications of the compounds under study.

  16. Periodontal Therapy Effects on Nitrite Related to Oral Bacteria: A 6-Month Randomized Clinical Trial.

    Science.gov (United States)

    Cortelli, Sheila C; Costa, Fernando O; Rodrigues, Edson; Cota, Luis O M; Cortelli, Jose R

    2015-08-01

    Nitrite is a biologic factor relevant to oral and systemic homeostasis. Through an oral bacteria reduction process, it was suggested that periodontal therapy and chlorhexidine (CHX) rinse could affect nitrite levels, leading to negative effects, such as an increase in blood pressure. This 6-month randomized clinical trial evaluated the effects of periodontal therapeutic protocols on salivary nitrite and its relation to subgingival bacteria. One hundred patients with periodontitis were allocated randomly to debridement procedures in four weekly sections (quadrant scaling [QS]) or within 24 hours (full-mouth scaling [FMS]) in conjunction with a 60-day CHX (QS + CHX and FMS + CHX), placebo (QS + placebo and FMS + placebo), or no mouthrinse (QS + none and FMS + none) use. Real-time polymerase chain reaction determined total bacterial, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Streptococcus oralis, and Actinomyces naeslundii levels. Salivary nitrite concentration was determined with Griess reagent. Data were analyzed statistically at baseline and 3 and 6 months by analysis of variance, Kruskal-Wallis, Mann-Whitney U, and Spearman correlation tests (P periodontal pockets. The relationship between nitrite and bacterial levels appears weak. Short-term scaling exhibited a greater influence on nitrite concentrations then long-term CHX use.

  17. NITRITE REDUCTASE ACTIVITY OF NON-SYMBIOTIC HEMOGLOBINS FROM ARABIDOPSIS THALIANA†

    Science.gov (United States)

    Tiso, Mauro; Tejero, Jesús; Kenney, Claire; Frizzell, Sheila; Gladwin, Mark T.

    2013-01-01

    Plant non-symbiotic hemoglobins possess hexa-coordinate heme geometry similar to the heme protein neuroglobin. We recently discovered that deoxygenated neuroglobin converts nitrite to nitric oxide (NO), an important signaling molecule involved in many processes in plants. We sought to determine whether Arabidopsis thaliana non-symbiotic hemoglobins class 1 and 2 (AHb1 and AHb2) might function as nitrite reductases. We found that the reaction of nitrite with deoxygenated AHb1 and AHb2 generates NO gas and iron-nitrosyl-hemoglobin species. The bimolecular rate constants for nitrite reduction to NO are 19.8 ± 3.2 and 4.9 ± 0.2 M−1s−1, at pH = 7.4 and 25°C, respectively. We determined the pH dependence of these bimolecular rate constants and found a linear correlation with the concentration of protons, indicating the requirement for one proton in the reaction. Release of free NO gas during reaction in anoxic and hypoxic (2% oxygen) conditions was confirmed by chemiluminescence detection. These results demonstrate that deoxygenated AHb1 and AHb2 reduce nitrite to form NO via a mechanism analogous to that observed for hemoglobin, myoglobin and neuroglobin. Our findings suggest that during severe hypoxia and in the anaerobic plant roots, especially in water submerged species, non-symbiotic hemoglobins provide a viable pathway for NO generation via nitrite reduction. PMID:22620259

  18. Haematological and ion regulatory effects of nitrite in the air-breathing snakehead fish Channa striata

    DEFF Research Database (Denmark)

    Lefevre, Sjannie; Jensen, Frank B.; Huong, Do T.T.

    2012-01-01

    M. Effects of sub-lethal exposures to nitrite (0 mM, 1.4 mM, and 3.0 mM) were determined during a 7-day exposure period. Plasma nitrite increased, but the internal concentration remained well below ambient levels. Extracellular nitrate rose by several mM, indicating that a large proportion of the nitrite...... taken up was converted to nitrate. Nitrite reacted with erythrocyte haemoglobin (Hb) causing methaemoglobin (metHb) to increase to 30% and nitrosylhaemoglobin (HbNO) to increase to 10% of total Hb. Both metHb and HbNO stabilised after 4 days, and functional Hb levels accordingly never fell below 60......The tolerance and effects of nitrite on ion balance and haematology were investigated in the striped snakehead, Channa striata Bloch 1793, which is an air-breathing fish with reduced gills of importance for aquaculture in South East Asia. C. striata was nitrite tolerant with a 96 h LC50 of 4.7 m...

  19. Enhanced Activity and Selectivity of Carbon Nanofiber Supported Pd Catalysts for Nitrite Reduction

    KAUST Repository

    Shuai, Danmeng

    2012-03-06

    Pd-based catalyst treatment represents an emerging technology that shows promise to remove nitrate and nitrite from drinking water. In this work we use vapor-grown carbon nanofiber (CNF) supports in order to explore the effects of Pd nanoparticle size and interior versus exterior loading on nitrite reduction activity and selectivity (i.e., dinitrogen over ammonia production). Results show that nitrite reduction activity increases by 3.1-fold and selectivity decreases by 8.0-fold, with decreasing Pd nanoparticle size from 1.4 to 9.6 nm. Both activity and selectivity are not significantly influenced by Pd interior versus exterior CNF loading. Consequently, turnover frequencies (TOFs) among all CNF catalysts are similar, suggesting nitrite reduction is not sensitive to Pd location on CNFs nor Pd structure. CNF-based catalysts compare favorably to conventional Pd catalysts (i.e., Pd on activated carbon or alumina) with respect to nitrite reduction activity and selectivity, and they maintain activity over multiple reduction cycles. Hence, our results suggest new insights that an optimum Pd nanoparticle size on CNFs balances faster kinetics with lower ammonia production, that catalysts can be tailored at the nanoscale to improve catalytic performance for nitrite, and that CNFs hold promise as highly effective catalyst supports in drinking water treatment. © 2012 American Chemical Society.

  20. Nitrite spray treatment to promote red color stability of vacuum packaged beef.

    Science.gov (United States)

    Song, Xiao; Cornforth, Daren; Whittier, Dick; Luo, Xin

    2015-01-01

    Sodium nitrite solutions were sprayed on select grade boneless rib (M. longissimus thoracis) and bottom round (mainly M. biceps femoris) steaks individually, to form bright red nitric oxide myoglobin (NO-Mb) in vacuum packages. Our objective was to determine the optimum level of nitrite in spray for stable raw steak redness, low or no residual nitrite, and low surface pinking (ham-like cured color) after cooking. Results showed that steaks sprayed with 100-350 ppm nitrite solutions had 3.0-3.6g weight gain and a calculated level of 1.3-5.3mg nitrite added/kg steak, but very low (color during 21 days of storage at 1°C (a*>10; chroma C*>16). Raw steak redness was less stable in round than rib. Visual scores for pinkness after cooking were low, indicating that cooked color at even the highest nitrite treatment (350 ppm) was acceptable. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Arabidopsis Root-Type Ferredoxin:NADP(H) Oxidoreductase 2 is Involved in Detoxification of Nitrite in Roots.

    Science.gov (United States)

    Hachiya, Takushi; Ueda, Nanae; Kitagawa, Munenori; Hanke, Guy; Suzuki, Akira; Hase, Toshiharu; Sakakibara, Hitoshi

    2016-11-01

    Ferredoxin:NADP(H) oxidoreductase (FNR) plays a key role in redox metabolism in plastids. Whereas leaf FNR (LFNR) is required for photosynthesis, root FNR (RFNR) is believed to provide electrons to ferredoxin (Fd)-dependent enzymes, including nitrite reductase (NiR) and Fd-glutamine-oxoglutarate aminotransferase (Fd-GOGAT) in non-photosynthetic conditions. In some herbal species, however, most nitrate reductase activity is located in photosynthetic organs, and ammonium in roots is assimilated mainly by Fd-independent NADH-GOGAT. Therefore, RFNR might have a limited impact on N assimilation in roots grown with nitrate or ammonium nitrogen sources. AtRFNR genes are rapidly induced by application of toxic nitrite. Thus, we tested the hypothesis that RFNR could contribute to nitrite reduction in roots by comparing Arabidopsis thaliana seedlings of the wild type with loss-of-function mutants of RFNR2 When these seedlings were grown under nitrate, nitrite or ammonium, only nitrite nutrition caused impaired growth and nitrite accumulation in roots of rfnr2 Supplementation of nitrite with nitrate or ammonium as N sources did not restore the root growth in rfnr2 Also, a scavenger for nitric oxide (NO) could not effectively rescue the growth impairment. Thus, nitrite toxicity, rather than N depletion or nitrite-dependent NO production, probably causes the rfnr2 root growth defect. Our results strongly suggest that RFNR2 has a major role in reduction of toxic nitrite in roots. A specific set of genes related to nitrite reduction and the supply of reducing power responded to nitrite concomitantly, suggesting that the products of these genes act co-operatively with RFNR2 to reduce nitrite in roots. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  2. Nitrite-Mediated Hypoxic Vasodilation Predicted from Mathematical Modeling and Quantified from in Vivo Studies in Rat Mesentery

    Directory of Open Access Journals (Sweden)

    Donald G. Buerk

    2017-12-01

    Full Text Available Nitric oxide (NO generated from nitrite through nitrite reductase activity in red blood cells has been proposed to play a major role in hypoxic vasodilation. However, we have previously predicted from mathematical modeling that much more NO can be derived from tissue nitrite reductase activity than from red blood cell nitrite reductase activity. Evidence in the literature suggests that tissue nitrite reductase activity is associated with xanthine oxidoreductase (XOR and/or aldehyde oxidoreductase (AOR. We investigated the role of XOR and AOR in nitrite-mediated vasodilation from computer simulations and from in vivo exteriorized rat mesentery experiments. Vasodilation responses to nitrite in the superfusion medium bathing the mesentery equilibrated with 5% O2 (normoxia or zero O2 (hypoxia at either normal or acidic pH were quantified. Experiments were also conducted following intraperitoneal (IP injection of nitrite before and after inhibiting XOR with allopurinol or inhibiting AOR with raloxifene. Computer simulations for NO and O2 transport using reaction parameters reported in the literature were also conducted to predict nitrite-dependent NO production from XOR and AOR activity as a function of nitrite concentration, PO2 and pH. Experimentally, the largest arteriolar responses were found with nitrite >10 mM in the superfusate, but no statistically significant differences were found with hypoxic and acidic conditions in the superfusate. Nitrite-mediated vasodilation with IP nitrite injections was reduced or abolished after inhibiting XOR with allopurinol (p < 0.001. Responses to IP nitrite before and after inhibiting AOR with raloxifene were not as consistent. Our mathematical model predicts that under certain conditions, XOR and AOR nitrite reductase activity in tissue can significantly elevate smooth muscle cell NO and can serve as a compensatory pathway when endothelial NO production is limited by hypoxic conditions. Our theoretical and

  3. Low nitrous oxide production through nitrifier-denitrification in intermittent-feed high-rate nitritation reactors

    DEFF Research Database (Denmark)

    Su, Qingxian; Ma, Chun; Domingo-Felez, Carlos

    2017-01-01

    Nitrous oxide (N2O) production from autotrophic nitrogen conversion processes, especially nitritation systems, can be significant, requires understanding and calls for mitigation. In this study, the rates and pathways of N2O production were quantified in two lab-scale sequencing batch reactors...... to maintain high nitritation efficiency and high nitritation rates at 20-26 °C over a period of ∼300 days. Even at the high nitritation efficiencies, net N2O production was low (∼2% of the oxidized ammonium). Net N2O production rates transiently increased with a rise in pH after each feeding, suggesting...... operated with intermittent feeding and demonstrating long-term and high-rate nitritation. The resulting reactor biomass was highly enriched in ammonia-oxidizing bacteria, and converted ∼93 ± 14% of the oxidized ammonium to nitrite. The low DO set-point combined with intermittent feeding was sufficient...

  4. Reduction of nitrogen oxides by gamma-irradiated hemoproteins. Pt. 2. Reduction of nitrite by immobilized gamma-irradiated hemoprotein

    International Nuclear Information System (INIS)

    Oku, Tadatake; Sato, Hitoshi; Ichikawa, Yoshinobu; Kaneko, Junko; Goto, Mituhiro; Nishio, Toshiyuki; Ito, Teiichiro; Kume, Tamikazu.

    1994-01-01

    Sodium and potassium nitrites are used for coloration and pasteurization of meat products as food additives. Recently, removal of nitrite in water has been one of the research area in environmental science because of the necessity of reducing water pollution. The horse cardiac cytochrome c in 0.1mM aqueous solution was denatured by gamma-irradiation at a dose of 10kGy in the presence of air, and was immobilized by lattice entrapment method in the polyacrylamide gel. The immobilized irradiated cytochrome c was reacted with nitrite in the presence of reducing agent (sodium hydrosulfite) and electron carrier (methyl viologen) at 30degC. The remaining nitrite was determined by diazo-reaction. Immobilized irradiated cytochrome c could be used as a substituent of nitrite reductase, and especially high nitrite reducing activity under nitrogen atmosphere in acidic range, and entrapment in 15% gel made possible to reuse denatured cytochrome c several times. (J.P.N.)

  5. De novo biofilm community assembly from tap water source communities favors Nitrotoga over Nitrospira under elevated nitrite surface loading

    DEFF Research Database (Denmark)

    Kinnunen, Marta; Dechesne, Arnaud; Albrechtsen, Hans-Jørgen

    -through biofilm system to continuous immigration from a tap water metacommunity while applying different nitrite surface loading rates. After 63 days of operation, we extracted biofilms and analyzed the community composition via Illumina MiSeq targeting the 16S rRNA gene. Previous studies have shown...... that Nitrospira is the dominant nitrite oxidizing genus in low nitrite environments. Hence, we postulated that by elevating the nitrite surface loading we would select for NOB with lower nitrite affinity than Nitrospira. We observed different dominant NOB species under different loading rates. While...... in the metacommunity, Nitrotoga and Nitrospira were found at near equal abundances, in the biofilm community, elevated nitrite loading strongly selected for Nitrotoga over Nitrospira. The biofilms were also significantly different in their alpha-diversity (pdiversity, and the evenness and richness...

  6. MONITORING KADAR NITRIT DAN NITRAT PADA AIR SUMUR DI DAERAH CATUR TUNGGAL YOGYAKARTA DENGAN METODE SPEKTROFOTOMETRI UV-VIS (Monitoring of Nitrite and Nitrate Content in Ground Water of Catur Tunggal Region of Yogyakarta by UV-VIS Spectrophotometry

    Directory of Open Access Journals (Sweden)

    Setiowati Setiowati

    2016-07-01

    Full Text Available ABSTRAK Metode analisis nitrit dan nitrat perlu dikembangkan untuk memonitor kualitas air minum. Kualitas air sumur untuk parameter nitrit dan nitrat dipengaruhi oleh kondisi lingkungan dan kedalaman air sumur.Penelitian ini bertujuan menganalisis nitrit dan nitrat menggunakan asam p-aminobenzoat (PABA pada air sumur di daerah perkotaan Yogyakarta. Analisis nitrit didasarkan pada reaksi antara ion nitrit dengan PABA yang membentuk senyawa azo dengan panjang gelombang maksimum 546 nm. Kedalaman air sumur di daerah Catur Tunggal rata-rata > 10 m. Kadar nitrit dan nitrat pada air sumur adalah 0,05-0,09 dan 8,22-36,58 mg/L. Kadar nitrit dan nitrat tersebut memenuhi baku mutu dan aman untuk dikonsumsi. Konsentrasi nitrit dan nitrat pada air RO adalah 0,05 dan 2,72-59,57 mg/L. Kadar nitrit pada air RO tidak memenuhi baku mutu sedangkan kadar nitrat memenuhi baku mutu kecuali RO 5. ABSTRACT The method for analysis nitrite and nitrate had to developed to monitor the drinking water quality. The well water quality, especially for nitrite and nitrate were influenced by environmental conditions and depth of well. This study aims to analyze nitrite and nitrate using p-aminobenzoic acid (PABA in ground water at urban areas of Yogyakarta. The analysis was based on the reaction between nitrite ions with PABA which form azo compounds with a maximum wavelength of 546 nm. The depth of wells at Catur Tunggal were more than 10 m. Concentration of nitrite and nitrate in well water were 0.05 to 0.09 and 8.22 to 36.58 mg / L. The concentrations met the standard for drinking water quality and was safe for consumption. The concentration of nitrite and nitrate in reverse osmosis (RO water were 0.05 and 2.72 to 59.57 mg / L. The concentration of nitrite did not meet the standard for drinking water quality while the concentration of nitrate met the standard for drinking water quality except RO 5.

  7. Thyroid cancer risk and dietary nitrate and nitrite intake in the Shanghai women's health study.

    Science.gov (United States)

    Aschebrook-Kilfoy, Briseis; Shu, Xiao-Ou; Gao, Yu-Tang; Ji, Bu-Tian; Yang, Gong; Li, Hong Lan; Rothman, Nathaniel; Chow, Wong-Ho; Zheng, Wei; Ward, Mary H

    2013-02-15

    Nitrate and nitrite are precursors in the endogenous formation of N-nitroso compounds and nitrate can disrupt thyroid homeostasis by inhibiting iodide uptake. We evaluated nitrate and nitrite intake and risk of thyroid cancer in the Shanghai Women's Health Study that included 73,317 women, aged 40-70 years enrolled in 1996-2000. Dietary intake was assessed at baseline using a food frequency questionnaire. During approximately 11 years of follow-up, 164 incident thyroid cancer cases with complete dietary information were identified. We used Cox proportional hazards regression to estimate relative risks (RRs). We determined the nitrate and nitrite contents of foods using values from the published literature and focusing on regional values for Chinese foods. Nitrate intake was not associated with thyroid cancer risk [RR(Q4) = 0.93; 95% confidence interval (CI): 0.42-2.07; p for trend = 0.40]. Compared to the lowest quartile, women with the highest dietary nitrite intake had about a twofold risk of thyroid cancer (RR(Q4) = 2.05; 95%CI: 1.20-3.51), but there was not a monotonic trend with increasing intake (p for trend = 0.36). The trend with increasing nitrite intake from animal sources was significant (p for trend = 0.02) and was stronger for nitrite from processed meats (RR(Q4) = 1.96; 95%CI: 1.28-2.99; p for trend nitrate as hypothesized, our results suggest that women consuming higher levels of nitrite from animal sources, particularly from processed meat, may have an increased risk of thyroid cancer. Copyright © 2012 UICC.

  8. Histological alterations in gills of Macrobrachium amazonicum juveniles exposed to ammonia and nitrite.

    Science.gov (United States)

    Dutra, Fabrício Martins; Rönnau, Milton; Sponchiado, Dircelei; Forneck, Sandra Carla; Freire, Carolina Arruda; Ballester, Eduardo Luis Cupertino

    2017-06-01

    Aquaculture has shown great growth in the last decades. Due to the restrictions on water use, production systems are becoming increasingly more intensive, raising concerns about the production water quality. Macrobrachium amazonicum is among the freshwater prawn species with favorable characteristics for production and possibility of intensification. Nitrogen compounds such as ammonia and nitrite affect the health of aquatic organisms since they quickly reach toxic concentrations. These compounds can also cause damage to the gill structure, leading to hypoxia in tissues, affecting acid-base balance, osmoregulation (salt absorption) and ammonia excretion, decreasing the immune capacity of the animal and, in extreme cases, cause death. The aim of this study was to assess histological changes in the gills of Macrobrachium amazonicum juveniles subjected to different concentrations of total ammonia and nitrite. The prawns were subjected to different concentrations of those compounds and their gills were removed and preserved for histological analysis. The gills were assessed for changes according to the Organ Index (I org ) and, for each change, an importance factor (w) was attributed according to the degree of reversibility and applied according to the degree of extension or frequency of the damage. The damage to the gills in the treatments with 100% mortality, both for ammonia and nitrite, corresponded to the high occurrence of progressive, regressive, circulatory, and inflammation damages. The other treatments (which caused less mortality) had mainly inflammation and regressive damages, whose occurrence increased according to the increase in ammonia and nitrite concentration. The histological analysis confirmed that the higher the total ammonia and nitrite concentrations, the larger the damages caused to the gill structure and that lower nitrite concentrations caused similar damages to those caused by higher total ammonia concentrations, which reflects the lower

  9. Aqueous nitrite ion determination by selective reduction and gas phase nitric oxide chemiluminescence

    Science.gov (United States)

    Dunham, A. J.; Barkley, R. M.; Sievers, R. E.; Clarkson, T. W. (Principal Investigator)

    1995-01-01

    An improved method of flow injection analysis for aqueous nitrite ion exploits the sensitivity and selectivity of the nitric oxide (NO) chemilluminescence detector. Trace analysis of nitrite ion in a small sample (5-160 microL) is accomplished by conversion of nitrite ion to NO by aqueous iodide in acid. The resulting NO is transported to the gas phase through a semipermeable membrane and subsequently detected by monitoring the photoemission of the reaction between NO and ozone (O3). Chemiluminescence detection is selective for measurement of NO, and, since the detection occurs in the gas-phase, neither sample coloration nor turbidity interfere. The detection limit for a 100-microL sample is 0.04 ppb of nitrite ion. The precision at the 10 ppb level is 2% relative standard deviation, and 60-180 samples can be analyzed per hour. Samples of human saliva and food extracts were analyzed; the results from a standard colorimetric measurement are compared with those from the new chemiluminescence method in order to further validate the latter method. A high degree of selectivity is obtained due to the three discriminating steps in the process: (1) the nitrite ion to NO conversion conditions are virtually specific for nitrite ion, (2) only volatile products of the conversion will be swept to the gas phase (avoiding turbidity or color in spectrophotometric methods), and (3) the NO chemiluminescence detector selectively detects the emission from the NO + O3 reaction. The method is free of interferences, offers detection limits of low parts per billion of nitrite ion, and allows the analysis of up to 180 microL-sized samples per hour, with little sample preparation and no chromatographic separation. Much smaller samples can be analyzed by this method than in previously reported batch analysis methods, which typically require 5 mL or more of sample and often need chromatographic separations as well.

  10. Ammonium and nitrite oxidation at nanomolar oxygen concentrations in oxygen minimum zone waters.

    Science.gov (United States)

    Bristow, Laura A; Dalsgaard, Tage; Tiano, Laura; Mills, Daniel B; Bertagnolli, Anthony D; Wright, Jody J; Hallam, Steven J; Ulloa, Osvaldo; Canfield, Donald E; Revsbech, Niels Peter; Thamdrup, Bo

    2016-09-20

    A major percentage of fixed nitrogen (N) loss in the oceans occurs within nitrite-rich oxygen minimum zones (OMZs) via denitrification and anammox. It remains unclear to what extent ammonium and nitrite oxidation co-occur, either supplying or competing for substrates involved in nitrogen loss in the OMZ core. Assessment of the oxygen (O2) sensitivity of these processes down to the O2 concentrations present in the OMZ core (Chile at manipulated O2 levels between 5 nmol⋅L(-1) and 20 μmol⋅L(-1) Rates of both processes were detectable in the low nanomolar range (5-33 nmol⋅L(-1) O2), but demonstrated a strong dependence on O2 concentrations with apparent half-saturation constants (Kms) of 333 ± 130 nmol⋅L(-1) O2 for ammonium oxidation and 778 ± 168 nmol⋅L(-1) O2 for nitrite oxidation assuming one-component Michaelis-Menten kinetics. Nitrite oxidation rates, however, were better described with a two-component Michaelis-Menten model, indicating a high-affinity component with a Km of just a few nanomolar. As the communities of ammonium and nitrite oxidizers were similar to other OMZs, these kinetics should apply across OMZ systems. The high O2 affinities imply that ammonium and nitrite oxidation can occur within the OMZ core whenever O2 is supplied, for example, by episodic intrusions. These processes therefore compete with anammox and denitrification for ammonium and nitrite, thereby exerting an important control over nitrogen loss.

  11. Safety and feasibility of long-term intravenous sodium nitrite infusion in healthy volunteers.

    Directory of Open Access Journals (Sweden)

    Ryszard M Pluta

    Full Text Available BACKGROUND: Infusion of sodium nitrite could provide sustained therapeutic concentrations of nitric oxide (NO for the treatment of a variety of vascular disorders. The study was developed to determine the safety and feasibility of prolonged sodium nitrite infusion. METHODOLOGY: Healthy volunteers, aged 21 to 60 years old, were candidates for the study performed at the National Institutes of Health (NIH; protocol 05-N-0075 between July 2007 and August 2008. All subjects provided written consent to participate. Twelve subjects (5 males, 7 females; mean age, 38.8±9.2 years (range, 21-56 years were intravenously infused with increasing doses of sodium nitrite for 48 hours (starting dose at 4.2 µg/kg/hr; maximal dose of 533.8 µg/kg/hr. Clinical, physiologic and laboratory data before, during and after infusion were analyzed. FINDINGS: The maximal tolerated dose for intravenous infusion of sodium nitrite was 267 µg/kg/hr. Dose limiting toxicity occurred at 446 µg/kg/hr. Toxicity included a transient asymptomatic decrease of mean arterial blood pressure (more than 15 mmHg and/or an asymptomatic increase of methemoglobin level above 5%. Nitrite, nitrate, S-nitrosothiols concentrations in plasma and whole blood increased in all subjects and returned to preinfusion baseline values within 12 hours after cessation of the infusion. The mean half-life of nitrite estimated at maximal tolerated dose was 45.3 minutes for plasma and 51.4 minutes for whole blood. CONCLUSION: Sodium nitrite can be safely infused intravenously at defined concentrations for prolonged intervals. These results should be valuable for developing studies to investigate new NO treatment paradigms for a variety of clinical disorders, including cerebral vasospasm after subarachnoid hemorrhage, and ischemia of the heart, liver, kidney and brain, as well as organ transplants, blood-brain barrier modulation and pulmonary hypertension. CLINICAL TRIAL REGISTRATION INFORMATION: http

  12. Formation of nitrous oxide in a gradient of oxygenation and nitrogen loading rate during denitrification of nitrite and nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Gong, You-Kui; Peng, Yong-Zhen [School of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100022 (China); Yang, Qing, E-mail: gykren@163.com [School of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100022 (China); Wu, Wei-Min [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090 (China); Wang, Shu-Ying [School of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100022 (China)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer The correlation of DO to N{sub 2}O emission under denitrification via nitrite was confirmed. Black-Right-Pointing-Pointer The higher nitrite ratio in NO{sub x} (nitrite and nitrate) caused the more N{sub 2}O emission. Black-Right-Pointing-Pointer Reactor feed mode and nitrite loading rate had significant impact on N{sub 2}O emission which was related to nitrite level. - Abstract: Nitrous oxide (N{sub 2}O) emission has been observed during denitrification of nitrate via nitrite as intermediate. With a laboratory-scale reactor (2.4 L), the N{sub 2}O emission was characterized under a gradient of DO concentration from 0 to 0.7 mg/L, different ratio of nitrite versus nitrate and different nitrite feed mode. The N{sub 2}O emission was influenced by the level of dissolved oxygen (DO) and nitrite accumulation. The higher DO level and the higher ratio of nitrite versus nitrate resulted in the higher N{sub 2}O emission. Using nitrite as sole electron acceptor at the same loading rate, the sequence of N{sub 2}O emission with three different feed modes was: pulse > step-wise > continuous feed. The N{sub 2}O emitted in pulse feed reactors was 3.1-4.2 and 8.2-11.7 folds of that in the step-wise feed and continuous feed reactors, respectively. With continuous feed mode, the impact of DO concentration on the mass of N{sub 2}O emitted was limited while the higher N{sub 2}O emission occurred at the higher nitrite loading rate.

  13. Calcium ferrite formation from the thermolysis of calcium tris (maleato)

    Indian Academy of Sciences (India)

    For preparing calcium ferrite, calcium tris (maleato) ferrate(III) precursor was prepared by mixing aqueous solutions of iron(III) maleate, calcium maleate and maleic acid. Various physico-chemical techniques i.e. TG, DTG, DTA, Mössbauer, XRD, IR etc have been used to study the decomposition behaviour from ambient to ...

  14. A sensor for calcium uptake

    Science.gov (United States)

    Collins, Sean; Meyer, Tobias

    2011-01-01

    Mitochondria — the cell’s power plants — increase their energy production in response to calcium signals in the cytoplasm. A regulator of the elusive mitochondrial calcium channel has now been identified. PMID:20844529

  15. Children's Bone Health and Calcium

    Science.gov (United States)

    ... Twitter Pinterest Email Print Children's Bone Health and Calcium: Condition Information What is bone health and how ... straight, walk, run, and lead an active life. Calcium is one of the key dietary building blocks ...

  16. Calcium – how and why?

    Indian Academy of Sciences (India)

    Unknown

    biological processes because of its unusual physical and chemical properties. 1. History of calcium ... cellular roles of calcium has established the importance of this ion ..... Ca2+ ion, for example in regulating enzyme activity (Price. 1975 ...

  17. Suspected nitrite poisoning in pigs caused by Capsella bursa-pastoris (L. Medik. ('herderstassie', shepherd's purse : case report

    Directory of Open Access Journals (Sweden)

    W.J. Wiese

    2001-07-01

    Full Text Available Nitrite poisoning in pigs was suspected when 4 of 18 pigs died in a piggery near Ellisras in the Northern Province. The pigs showed typical brownish discolouration of the blood at autopsy. It was established that they ingested vegetable tops and weeds from the adjacent garden as part of their daily ration. Of the available plants, only Capsella bursa-pastoris contained nitrites. The drinking water and some of the other plants tested positive for nitrates but not for nitrites. This is the first report of suspected nitrite poisoning in pigs caused by Capsella bursa-pastoris.

  18. Dramatic increase of nitrite levels in hearts of anoxia-exposed crucian carp supporting a role in cardioprotection

    DEFF Research Database (Denmark)

    Sandvik, Guro K.; Nilsson, Göran E.; Jensen, Frank Bo

    2012-01-01

    the generation of reactive oxygen species upon reoxygenation. The crucian carp naturally survives extended periods without oxygen in an active state, which has made it a model for studying how evolution has solved the problems of anoxic survival. We investigated the role of nitrite and NO in the anoxia...... increases in nitrite, S-nitrosothiols (SNO) and iron-nitrosyl (FeNO) compounds in anoxic heart tissue. Nitrite levels were maintained in anoxic brain, liver and gill tissues, whereas SNO and FeNO increased in a tissue-specific manner. Reoxygenation reestablished normoxic values. We conclude that nitrite...

  19. Solar Imagery - Chromosphere - Calcium

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset consists of full-disk images of the sun in Calcium (Ca) II K wavelength (393.4 nm). Ca II K imagery reveal magnetic structures of the sun from about 500...

  20. Amperometric detection of nitrite based on Dawson-type vanodotungstophosphate and carbon nanotubes

    International Nuclear Information System (INIS)

    Zhang, Di; Ma, Huiyuan; Chen, Yanyan; Pang, Haijun; Yu, Yan

    2013-01-01

    Graphical abstract: A composite film has been constructed by vanodotungstophosphate α 2 -K 7 P 2 VW 17 O 62 ·18H 2 O (P 2 W 17 V) and carbon nanotubes (CNTs) using the layer-by-layer self-assembly method. The incorporation of CNTs and P 2 W 17 V into the composite film endowed the modified electrode fast electron transfer rate and high electrocatalytic activity of toward nitrite oxidation. This nitrite sensor shows broad linear range, low detection limit, and high sensitivity and stability. Also it did not show any interference with other potential interfering species, and was successfully employed for determination of nitrite in real samples. -- Highlights: •A composite film was constructed by a vanodotungstophosphate and carbon nanotubes. •The composite film showed fast electron transfer rate and high electrocatalytic activity of toward nitrite oxidation. •The proposed sensor can amperometricially detect nitrite with high sensitivity and selectivity. -- Abstract: A nitrite sensor based on Dawson vanodotungstophosphates α 2 -K 7 P 2 VW 17 O 62 ·18H 2 O (P 2 W 17 V) and carbon nanotubes (CNTs) was prepared by electrostatic layer-by-layer self-assembly technique. The sensor {PEI/PSS/[PDDA/P 2 W 17 V-CNTs] n } was characterized by UV–vis spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray photoelectron spectra (XPS). The electron transfer and sensing ability of this sensor were explored using cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) technology. The results show that the incorporation of CNTs and P 2 W 17 V into the composite film endowed the modified electrode with fast transfer rate and high electrocatalytic activity towards oxidation of nitrite. This nitrite sensor with 10 bilayers has a broad linear range of 5 × 10 −8 to 2.13 × 10 −3 M, a low detection limit of 0.0367 μM (S N −1 = 3), a high sensitivity of 0.35 mA mM −1 NO 2 − , an excellent anti-interference property in the

  1. Reverse polarity capillary zone electrophoresis analysis of nitrate and nitrite in natural water samples

    Energy Technology Data Exchange (ETDEWEB)

    Metcalf, S.G.

    1998-06-11

    This paper describes the application of reverse polarity capillary zone electrophoresis (RPCE) for rapid and accurate determination of nitrate and nitrite in natural water samples. Using hexamethonium bromide (HMB) as an electroosmotic flow modifier in a borate buffer at pH 9.2, the resolution of nitrate and nitrite was accomplished in less than 3 minutes. RPCE was compared with ion chromatographic (IC) and cadmium reduction flow injection analysis (Cd-FIA) methods which are the two most commonly used standard methods for the analysis of natural water samples for nitrate and nitrite. When compared with the ion chromatographic method for the determination of nitrate and nitrite, RPCE reduced analysis time, decreased detection limits by a factor of 10, cut laboratory wastes by more than two orders of magnitude, and eliminated interferences commonly associated with IC. When compared with the cadmium reduction method, RPCE had the advantage of simultaneous determination of nitrate and nitrite, could be used in the presence of various metallic ions that normally interfere in cadmium reduction, and decreased detection limits by a factor of 10.

  2. Molecular characterization of Lactobacillus plantarum DMDL 9010, a strain with efficient nitrite degradation capacity.

    Directory of Open Access Journals (Sweden)

    Yong-tao Fei

    Full Text Available Nitrites commonly found in food, especially in fermented vegetables, are potential carcinogens. Therefore, limiting nitrites in food is critically important for food safety. A Lactobacillus strain (Lactobacillus sp. DMDL 9010 was previously isolated from fermented vegetables by our group, and is not yet fully characterized. A number of phenotypical and genotypical approaches were employed to characterize Lactobacillus sp. DMDL 9010. Its nitrite degradation capacity was compared with four other Lactobacillus strains, including Lactobacillus casei subsp. rhamnosus 719, Lactobacillus delbrueckii subsp. bulgaricu 1.83, Streptococcus thermophilus 1.204, and lactobacillus plantarum 8140, on MRS medium. Compared to these four Lactobacillus strains, Lactobacillus sp. DMDL 9010 had a significantly higher nitrite degradation capacity (P<0.001. Based on 16S rDNA sequencing and sequence comparison, Lactobacillus sp. DMDL 9010 was identified as either Lactobacillus plantarum or Lactobacillus pentosus. To further identify this strain, the flanking regions (922 bp and 806 bp upstream and downstream, respectively of the L-lactate dehydrogenase 1 (L-ldh1 gene were amplified and sequenced. Lactobacillus sp. DMDL 9010 had 98.92 and 76.98% sequence identity in the upstream region with L. plantarum WCFS1 and L. pentosus IG1, respectively, suggesting that Lactobacillu sp. DMDL 9010 is an L. plantarum strain. It was therefore named L. plantarum DMDL 9010. Our study provides a platform for genetic engineering of L. plantarum DMDL 9010, in order to further improve its nitrite degradation capacity.

  3. A genetic screen reveals a periplasmic copper chaperone required for nitrite reductase activity in pathogenic Neisseria.

    Science.gov (United States)

    Jen, Freda E-C; Djoko, Karrera Y; Bent, Stephen J; Day, Christopher J; McEwan, Alastair G; Jennings, Michael P

    2015-09-01

    Under conditions of low oxygen availability, Neisseria meningitidis and Neisseria gonorrhoeae are able to respire via a partial denitrification pathway in which nitrite is converted to nitrous oxide. In this process, nitrite reductase (AniA), a copper (Cu)-containing protein converts nitrite to NO, and this product is converted to nitrous oxide by nitric oxide reductase (NorB). NorB also confers protection against toxic NO, and so we devised a conditional lethal screen, using a norB mutant, to identify mutants that were resistant to nitrite-dependent killing. After random-deletion mutagenesis of N. meningitidis, this genetic screen identified a gene encoding a Cu chaperone that is essential for AniA function, AccA. Purified AccA binds one Cu (I) ion and also possesses a second binding site for Cu (II). This novel periplasmic Cu chaperone (AccA) appears to be essential for provision of Cu ions to AniA of pathogenic Neisseria to generate an active nitrite reductase. Apart from the Neisseria genus, AccA is distributed across a wide range of environmental Proteobacteria species. © FASEB.

  4. Association of nitrate, nitrite, and total organic carbon (TOC) in drinking water and gastrointestinal disease.

    Science.gov (United States)

    Khademikia, Samaneh; Rafiee, Zahra; Amin, Mohammad Mehdi; Poursafa, Parinaz; Mansourian, Marjan; Modaberi, Amir

    2013-01-01

    We aimed to investigate the amounts of nitrate, nitrite, and total organic carbon (TOC) in two drinking water sources and their relationship with some gastrointestinal diseases. This cross-sectional study was conducted in 2012 in Iran. Two wells located in residential areas were selected for sampling and measuring the TOC, nitrate (NO3(-)), and nitrite (NO2(-)). This water is used for drinking as well as for industrial and agricultural consumption. Nitrate and nitrite concentrations of water samples were analyzed using DR 5000 spectrophotometer. The information of patients was collected from the records of the main referral hospital of the region for gastrointestinal diseases. In both areas under study, the mean water nitrate and nitrite concentrations were higher in July than in other months. The mean TOC concentrations in areas 1 and 2 were 2.29 ± 0.012 and 2.03 ± 0.309, respectively. Pollutant concentration and gastrointestinal disease did not show any significant relationship (P > 0.05). Although we did not document significant association of nitrite, nitrate, and TOC content of water with gastrointestinal diseases, it should be considered that such health hazards may develop over time, and the quality of water content should be controlled to prevent different diseases.

  5. A new system for the spectrophotometric determination of trace amounts of nitrite in environmental samples

    Directory of Open Access Journals (Sweden)

    Cherian Tom

    2006-01-01

    Full Text Available A selective and rapid spectrophotometric method for the determination of nitrite is presented. It is based on the reaction of nitrite with p-nitroaniline in acid medium to form diazonium ion, which is coupled with ethoxyethylenemaleic ester or ethylcyanoacetate in basic medium to form azo dyes, showing absorption maxima at 439 and 465 nm respectively. The method obeys Beer's law in the concentration range of 0.5-16 µg mL-1 of nitrite with ethoxyethylenemaleic ester and 0.2-18 µg mL-1 of nitrite with ethylcyanoacetate. The molar absorptivity and Sandell's sensitivity of p-nitroaniline-ethoxyethylenemaleic ester and p-nitroaniline-ethylcyanoacetate azo dyes are 5.04 X 10(4 L mol-1cm-1, 0.98 X 10-2 µg cm-2 and 1.21 X 10(4 L mol-1 cm-1, 0.98 X 10-2 µg cm-2 respectively. The optimum reaction conditions and other analytical parameters were evaluated. The method was successfully applied to the determination of nitrite in various water samples and soil samples.

  6. Experimental studies of methemoglobinemia due to percutaneous absorption of sodium nitrite.

    Science.gov (United States)

    Saito, T; Takeichi, S; Nakajima, Y; Yukawa, N; Osawa, M

    1997-01-01

    Methemoglobin formation caused by a liniment solution containing sodium nitrite (30 g/L and 140 g/L) was studied in rats with normal or abraded skin, by measuring the methemoglobin concentration before and after application of liniment solutions with differing nitrite concentration. Each liniment solution (120 microL) was applied. Methemoglobin was measured for 180 minutes using a hemoximeter. Simultaneously, arterial blood pressure and cutaneous blood flow was measured by laser Doppler flowmetry and a pressure transducer. After the application of each liniment solution to normal skin, the methemoglobin concentration was not significantly modified depending on the time after application. Application of liniment solution to abraded skin (140 g/L) resulted in a marked increase in methemoglobin concentration. A remarkable decrease in arterial blood pressure and subcutaneous blood flow were observed after application of liniment solution to abraded skin (140 g/L). Each of these findings are characteristic of nitrite and they imply the percutaneous absorption of nitrite. Regardless of the nitrite concentration, the methemoglobin concentration was consistently higher in abraded skin than in normal skin.

  7. Effect of sodium ascorbate and sodium nitrite on protein and lipid oxidation in dry fermented sausages.

    Science.gov (United States)

    Berardo, A; De Maere, H; Stavropoulou, D A; Rysman, T; Leroy, F; De Smet, S

    2016-11-01

    The effects of sodium nitrite and ascorbate on lipid and protein oxidation were studied during the ripening process of dry fermented sausages. Samples were taken at day 0, 2, 8, 14, 21 and 28 of ripening to assess lipid (malondialdehyde) and protein (carbonyls and sulfhydryl groups) oxidation. Sodium ascorbate and nitrite were separately able to reduce the formation of malondialdehyde. Their combined addition resulted in higher amounts of carbonyl compounds compared to their separate addition or the treatment without any of both compounds. Moreover, sodium nitrite limited the formation of γ-glutamic semialdehyde whereas sodium ascorbate showed a pro-oxidant effect. A loss of thiol groups was observed during ripening, which was not affected by the use of sodium ascorbate nor sodium nitrite. In conclusion, sodium nitrite and ascorbate affected protein and lipid oxidation in different manners. The possible pro-oxidant effect of their combined addition on carbonyl formation might influence the technological and sensory properties of these products. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Properties of aqueous nitrate and nitrite from x-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Jacob W.; Lam, Royce K.; Saykally, Richard J., E-mail: saykally@berkeley.edu [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Shih, Orion [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China); Rizzuto, Anthony M. [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Prendergast, David [The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2015-08-28

    Nitrate and nitrite ions are of considerable interest, both for their widespread use in commercial and research contexts and because of their central role in the global nitrogen cycle. The chemistry of atmospheric aerosols, wherein nitrate is abundant, has been found to depend on the interfacial behavior of ionic species. The interfacial behavior of ions is determined largely by their hydration properties; consequently, the study of the hydration and interfacial behavior of nitrate and nitrite comprises a significant field of study. In this work, we describe the study of aqueous solutions of sodium nitrate and nitrite via X-ray absorption spectroscopy (XAS), interpreted in light of first-principles density functional theory electronic structure calculations. Experimental and calculated spectra of the nitrogen K-edge XA spectra of bulk solutions exhibit a large 3.7 eV shift between the XA spectra of nitrate and nitrite resulting from greater stabilization of the nitrogen 1s energy level in nitrate. A similar shift is not observed in the oxygen K-edge XA spectra of NO{sub 3}{sup −} and NO{sub 2}{sup −}. The hydration properties of nitrate and nitrite are found to be similar, with both anions exhibiting a similar propensity towards ion pairing.

  9. A coupled system of half-nitritation and ANAMMOX for mature landfill leachate nitrogen removal.

    Science.gov (United States)

    Li, Yun; Li, Jun; Zhao, Baihang; Wang, Xiujie; Zhang, Yanzhuo; Wei, Jia; Bian, Wei

    2017-09-01

    A coupled system of membrane bioreactor-nitritation (MBR-nitritation) and up-flow anaerobic sludge blanket-anaerobic ammonium oxidation (UASB-ANAMMOX) was employed to treat mature landfill leachate containing high ammonia nitrogen and low C/N. MBR-nitritation was successfully realized for undiluted mature landfill leachate with initial concentrations of 900-1500 mg/L [Formula: see text] and 2000-4000 mg/L chemical oxygen demand. The effluent [Formula: see text] concentration and the [Formula: see text] accumulation efficiency were 889 mg/L and 97% at 125 d, respectively. Half-nitritation was quickly realized by adjustment of hydraulic retention time and dissolved oxygen (DO), and a low DO control strategy could allow long-term stable operation. The UASB-ANAMMOX system showed high effective nitrogen removal at a low concentration of mature landfill leachate. The nitrogen removal efficiency was inhibited at excessive influent substrate concentration and the nitrogen removal efficiency of the system decreased as the concentration of mature landfill leachate increased. The MBR-nitritation and UASB-ANAMMOX processes were coupled for mature landfill leachate treatment and together resulted in high effective nitrogen removal. The effluent average total nitrogen concentration and removal efficiency values were 176 mg/L and 83%, respectively. However, the average nitrogen removal load decreased from 2.16 to 0.77 g/(L d) at higher concentrations of mature landfill leachate.

  10. Molecular characterization of Lactobacillus plantarum DMDL 9010, a strain with efficient nitrite degradation capacity.

    Science.gov (United States)

    Fei, Yong-tao; Liu, Dong-mei; Luo, Tong-hui; Chen, Gu; Wu, Hui; Li, Li; Yu, Yi-gang

    2014-01-01

    Nitrites commonly found in food, especially in fermented vegetables, are potential carcinogens. Therefore, limiting nitrites in food is critically important for food safety. A Lactobacillus strain (Lactobacillus sp. DMDL 9010) was previously isolated from fermented vegetables by our group, and is not yet fully characterized. A number of phenotypical and genotypical approaches were employed to characterize Lactobacillus sp. DMDL 9010. Its nitrite degradation capacity was compared with four other Lactobacillus strains, including Lactobacillus casei subsp. rhamnosus 719, Lactobacillus delbrueckii subsp. bulgaricu 1.83, Streptococcus thermophilus 1.204, and lactobacillus plantarum 8140, on MRS medium. Compared to these four Lactobacillus strains, Lactobacillus sp. DMDL 9010 had a significantly higher nitrite degradation capacity (PLactobacillus sp. DMDL 9010 was identified as either Lactobacillus plantarum or Lactobacillus pentosus. To further identify this strain, the flanking regions (922 bp and 806 bp upstream and downstream, respectively) of the L-lactate dehydrogenase 1 (L-ldh1) gene were amplified and sequenced. Lactobacillus sp. DMDL 9010 had 98.92 and 76.98% sequence identity in the upstream region with L. plantarum WCFS1 and L. pentosus IG1, respectively, suggesting that Lactobacillu sp. DMDL 9010 is an L. plantarum strain. It was therefore named L. plantarum DMDL 9010. Our study provides a platform for genetic engineering of L. plantarum DMDL 9010, in order to further improve its nitrite degradation capacity.

  11. Tumor induction in rats by feeding aminopyrine or oxytetracycline with nitrite

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, H W; Luinsky, W

    1975-01-01

    Sprague-Dawley rats were given combinations of aminopyrine or oxytetracycline and sodium nitrite in drinking water. Of 30 animals receiving 0.1 percent (1,000 ppm) of aminopyrine and sodium nitrite for 30 weeks, 29 died with hemangioendothelial sarcomas of the liver. The same tumor caused death in 26 of 30 animals that received 0.025 percent (250 ppm) of both aminopyrine and sodium nitrite for 50 weeks. No animals in a control group of the same size that received 0.1 percent aminopyrine for 30 weeks developed this tumor, although one-half of them were still alive 2 years after the experiment was begun. After feeding a comparable dose (0.1 percent) of oxytetracycline and sodium nitrite for 60 weeks, liver tumors were present in 4 of 30 rats (3 hepatocellular tumors and 1 cholangioma). Since aminopyrine has been widely used for medicinal purposes in the human population, it is possible that many people have been exposed to a potent carcinogen (dimethylnitrosamine) by its formation in vivo. It is not certain whether the result of feeding oxytetracycline and sodium nitrite indicates significant carcinogenicity of this combination. (auth)

  12. Reverse polarity capillary zone electrophoresis analysis of nitrate and nitrite in natural water samples

    International Nuclear Information System (INIS)

    Metcalf, S.G.

    1998-01-01

    This paper describes the application of reverse polarity capillary zone electrophoresis (RPCE) for rapid and accurate determination of nitrate and nitrite in natural water samples. Using hexamethonium bromide (HMB) as an electroosmotic flow modifier in a borate buffer at pH 9.2, the resolution of nitrate and nitrite was accomplished in less than 3 minutes. RPCE was compared with ion chromatographic (IC) and cadmium reduction flow injection analysis (Cd-FIA) methods which are the two most commonly used standard methods for the analysis of natural water samples for nitrate and nitrite. When compared with the ion chromatographic method for the determination of nitrate and nitrite, RPCE reduced analysis time, decreased detection limits by a factor of 10, cut laboratory wastes by more than two orders of magnitude, and eliminated interferences commonly associated with IC. When compared with the cadmium reduction method, RPCE had the advantage of simultaneous determination of nitrate and nitrite, could be used in the presence of various metallic ions that normally interfere in cadmium reduction, and decreased detection limits by a factor of 10

  13. Sensitive paper-based analytical device for fast colorimetric detection of nitrite with smartphone.

    Science.gov (United States)

    Zhang, Xiu-Xiu; Song, Yi-Zhen; Fang, Fang; Wu, Zhi-Yong

    2018-04-01

    On-site rapid monitoring of nitrite as an assessment indicator of the environment, food, and physiological systems has drawn extensive attention. Here, electrokinetic stacking (ES) was combined with colorimetric reaction on a paper-based device (PAD) to achieve colorless nitrite detection with smartphone. In this paper, nitrite was stacked on the paper fluidic channel as a narrow band by electrokinetic stacking. Then, Griess reagent was introduced to visualize the stacking band. Under optimal conditions, the sensitivity of nitrite was 160-fold increased within 5 min. A linear response in the range of 0.075 to 1.0 μg mL -1 (R 2  = 0.99) and a limit of detection (LOD) of 73 ng mL -1 (0.86 μM) were obtained. The LOD was 10 times lower than the reported PAD, and close to that achieved by a desktop spectrophotometer. The applicability was demonstrated by nitrite detection from saliva and water with good selectivity, adding 100 times more concentrated co-ions. High recovery (91.0~108.7%) and reasonable intra-day and inter-day reproducibility (RSD work shows that the sensitivity of colorless analyte detection-based colorimetric reaction can be effectively enhanced by integration of ES on a PAD. Graphical abstract Schematic of the experimental setups (left) and the corresponding images (right) of the actual portable device.

  14. Isolation of Ochrobactrum sp.QZ2 from sulfide and nitrite treatment system

    International Nuclear Information System (INIS)

    Mahmood, Qaisar; Hu Baolan; Cai Jing; Zheng Ping; Azim, Muhammad Rashid; Jilani, Ghulam; Islam, Ejazul

    2009-01-01

    A bacterial strain QZ2 was isolated from sludge of anoxic sulfide-oxidizing (ASO) reactor. Based on 16S rDNA sequence analysis and morphology, the isolate was identified as Ochrobactrum sp. QZ2. The strain was facultative chemolithotroph, able of using sulfide to reduce nitrite anaerobically. It produced either elemental sulfur or sulfate as the product of sulfide oxidation, depending on the initial sulfide and nitrite concentrations. The optimum growth pH and temperature for Ochrobactrum sp. QZ2 were found as 6.5-7.0 and 30 deg. C, respectively. The specific growth rate (μ) was found as 0.06 h -1 with a doubling time of 19.75 h; the growth seemed more sensitive to highly alkaline pH. Ochrobactrum sp. QZ2 catalyzed sulfide oxidation to sulfate was more sensitive to sulfide compared with nitrite as indicated by IC 50 values for sulfide and nitrite utilization implying that isolate was relatively more tolerant to nitrite. The comparison of physiology of Ochrobactrum sp. QZ2 with those of other known sulfide-oxidizing bacteria suggested that the present isolate resembled to Ochrobactrum anthropi in its denitrification ability.

  15. Antenatal calcium intake in Malaysia.

    Science.gov (United States)

    Mahdy, Zaleha Abdullah; Basri, Hashimah; Md Isa, Zaleha; Ahmad, Shuhaila; Shamsuddin, Khadijah; Mohd Amin, Rahmah

    2014-04-01

    To determine the adequacy of antenatal calcium intake in Malaysia, and the influencing factors. A cross-sectional study was conducted among postnatal women who delivered in two tertiary hospitals. Data were collected from antenatal cards, hospital documents and diet recall on daily milk and calcium intake during pregnancy. SPSS version 19.0 was used for statistical analyses. A total of 150 women were studied. The total daily calcium intake was 834 ± 43 mg (mean ± standard error of the mean), but the calcium intake distribution curve was skewed to the right with a median intake of 725 mg daily. When calcium intake from milk and calcium supplements was excluded, the daily dietary calcium intake was only 478 ± 25 mg. Even with inclusion of milk and calcium supplements, more than a third (n=55 or 36.7%) of the women consumed less than 600 mg calcium in their daily diet. The adequacy of daily calcium intake was not influenced by maternal age, ethnicity, income or maternal job or educational status as well as parity. The daily dietary calcium intake of the Malaysian antenatal population is far from adequate without the addition of calcium supplements and milk. © 2013 The Authors. Journal of Obstetrics and Gynaecology Research © 2013 Japan Society of Obstetrics and Gynecology.

  16. The Plasma Membrane Calcium Pump

    Science.gov (United States)

    Rasmussen, H.

    1983-01-01

    Three aspect of cellular calcium metabolism in animal cells was discussed including the importance of the plasma membrane in calcium homeostasis, experiments dealing with the actual mechanism of the calcium pump, and the function of the pump in relationship to the mitochondria and to the function of calmodulin in the intact cell.

  17. Voltage-Gated Calcium Channels

    Science.gov (United States)

    Zamponi, Gerald Werner

    Voltage Gated Calcium Channels is the first comprehensive book in the calcium channel field, encompassing over thirty years of progress towards our understanding of calcium channel structure, function, regulation, physiology, pharmacology, and genetics. This book balances contributions from many of the leading authorities in the calcium channel field with fresh perspectives from risings stars in the area, taking into account the most recent literature and concepts. This is the only all-encompassing calcium channel book currently available, and is an essential resource for academic researchers at all levels in the areas neuroscience, biophysics, and cardiovascular sciences, as well as to researchers in the drug discovery area.

  18. Nitrites and nitrates in exhaled breath condensate in cystic fibrosis: relation to clinical parameters.

    Science.gov (United States)

    Fila, L; Chladek, J; Maly, M; Musil, J

    2013-01-01

    To evaluate correlation of exhaled breath condensate (EBC) nitrite and nitrate concentrations with disease severity in cystic fibrosis (CF) patients. Nitrites and nitrates are products of oxidative metabolism of nitric oxide. Impaired metabolism of nitric oxide plays a role in pathogenesis of CF. EBC was collected from 46 stable CF patients and from 21 healthy controls. EBC concentrations of nitrites and nitrates were correlated with parameters of lung disease and nutritional status and with systemic inflammatory markers. EBC nitrates concentrations in CF patients were lower than in healthy subjects (5.8 vs 14.3 μmol/l, pnitrates concentrations correlate with disease severity in CF patients and are lower than in healthy subjects (Tab. 4, Fig. 1, Ref. 48).

  19. Nitrite accumulation in continuous-flow partial autotrophic denitrification reactor using sulfide as electron donor.

    Science.gov (United States)

    Liu, Chunshuang; Li, Wenfei; Li, Xuechen; Zhao, Dongfeng; Ma, Bin; Wang, Yongqiang; Liu, Fang; Lee, Duu-Jong

    2017-11-01

    The nitrite accumulation in handling nitrate and sulfide-laden wastewater in a continuous-flow upflow anaerobic sludge blanket reactor was studied. At sulfide/nitrate-nitrogen ratio of 1:0.76 and loading rates of 1.2kg-Sm -3 d -1 and 0.4kg-Nm -3 d -1 , the elemental sulfur and nitrite accumulation rates peaked at 90% and 70%, respectively, with Acrobacter, Azoarcus and Thauera presenting the functional strains in the studied reactor. The accumulated nitrite was proposed a promising feedstock for anaerobic ammonia oxidation process. An integrated partial autotrophic denitrification-anaerobic ammonia oxidation-aeration process for handling the ammonia and sulfide-laden wastewaters is proposed for further studies. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Development of a method to manufacture uncured, no-nitrate/nitrite-added whole muscle jerky.

    Science.gov (United States)

    Sindelar, Jeffrey J; Terns, Matthew J; Meyn, Elizabeth; Boles, Jane A

    2010-10-01

    "Natural curing" is accomplished by use of vegetable juice/powder high in naturally occurring nitrates combined with a nitrate reducing starter culture to result in indirectly "cured" products. Since the starter culture used is not water soluble, making "naturally cured" whole muscle jerky with current manufacturing techniques has been found ineffective. The objective was to investigate processes for whole muscle beef jerky that might provide cured meat characteristics similar to those of a nitrite-added control. Treatments where jerky was placed in a barrier bag during incubation were found to be the least similar to the nitrite-added control. Jerky placed in a 40.6 degrees C smokehouse during incubation resulted in significantly more (Pprocessing methods investigated to manufacture "naturally cured" whole muscle jerky in this study were ineffective in resulting in products similar to those cured with sodium nitrite. Published by Elsevier Ltd.

  1. Aggregate size and architecture determine biomass activity for one-stage partial nitritation and anammox

    DEFF Research Database (Denmark)

    Vlaeminck, S.; Terada, Akihiko; Smets, Barth F.

    2010-01-01

    to the inoculation and operation of the reactors. Fluorescent in-situ hybridization (FISH) was applied on aggregate sections to quantify AerAOB and AnAOB, as well as to visualize the aggregate architecture. The activity balance of the aggregates was calculated as the nitrite accumulation rate ratio (NARR), i...... and nitrite sources (NARR, > 1.7). Large A and C aggregates were granules capable of autonomous nitrogen removal (NARR, 0.6 to 1.1) with internal AnAOB zones surrounded by an AerAOB rim. Around 50% of the autotrophic space in these granules consisted of AerAOB- and AnAOB-specific EPS. Large B aggregates were...... thin film-like nitrite sinks (NARR,

  2. Reaction mixtures formed by nitrite and selected sulfa-drugs showed mutagenicity in acidic medium

    Directory of Open Access Journals (Sweden)

    Claudia Trossero

    2009-01-01

    Full Text Available Nitrite, which is present in preserved meat and can be produced in the oral cavity by reduction of nitrate taken from vegetables, could react in stomach with nitrosatable drugs, giving genotoxic-carcinogenic N-nitroso compounds (NOC. The mutagenicity of reaction mixtures formed by sodium nitrite and selected sulfa-drugs (sulfathiazole, HST; phtalylsulfathiazole, PhST; complex Co(II-sulfathiazole, Co(II-ST in acidic medium was evaluated using the Salmonella typhimurium reverse mutation assay (Ames test, with TA98 and TA 100 strains. The reactions were carried out at room temperature, with a mole ratio [nitrite]/[sulfa-drug] > 1. The three reaction mixtures showed mutagenic effects in the considered range.

  3. Electrochemical Determination of Food Preservative Nitrite with Gold Nanoparticles/p-Aminothiophenol-Modified Gold Electrode.

    Science.gov (United States)

    Üzer, Ayşem; Sağlam, Şener; Can, Ziya; Erçağ, Erol; Apak, Reşat

    2016-08-02

    Due to the negative impact of nitrate and nitrite on human health, their presence exceeding acceptable levels is not desired in foodstuffs. Thus, nitrite determination at low concentrations is a major challenge in electroanalytical chemistry, which can be achieved by fast, cheap, and safe electrochemical sensors. In this work, the working electrode (Au) was functionalized with p-aminothiophenol (p-ATP) and modified with gold nanoparticles (Au-NPs) to manufacture the final (Au/p-ATP-Aunano) electrode in a two-step procedure. In the first step, p-ATP was electropolymerized on the electrode surface to obtain a polyaminothiophenol (PATP) coating. In the second step, Au/p-ATP-Aunano working electrode was prepared by coating the surface with the use of HAuCl₄ solution and cyclic voltammetry. Determination of aqueous nitrite samples was performed with the proposed electrode (Au/p-ATP-Aunano) using square wave voltammetry (SWV) in pH 4 buffer medium. Characteristic peak potential of nitrite samples was 0.76 V, and linear calibration curves of current intensity versus concentration was linear in the range of 0.5-50 mg·L(-1) nitrite with a limit of detection (LOD) of 0.12 mg·L(-1). Alternatively, nitrite in sausage samples could be colorimetrically determined with high sensitivity by means of p-ATP‒modified gold nanoparticles (AuNPs) and naphthylethylene diamine as coupling agents for azo-dye formation due to enhanced charge-transfer interactions with the AuNPs surface. The slopes of the calibration lines in pure NO₂(-) solution and in sausage sample solution, to which different concentrations of NO₂(-) standards were added, were not significantly different from each other, confirming the robustness and interference tolerance of the method. The proposed voltammetric sensing method was validated against the colorimetric nanosensing method in sausage samples.

  4. Nitrates and nitrites in selected vegetables purchased at supermarkets in Siedlce, Poland.

    Science.gov (United States)

    Raczuk, Jolanta; Wadas, Wanda; Głozak, Katarzyna

    2014-01-01

    Vegetables constitute a vital part of the human diet, being the main source of minerals, vitamins, dietary fibre and phytochemicals. They however, also contain nitrates and nitrites, which adversely affect human health. To determine nitrate and nitrite content in selected vegetables purchased at supermarket chains in Siedlce and to assess their impact on consumer health. Vegetable samples were purchased from local supermarkets in Siedlce, town situated in the Mazovian province (Voivodeship) of Poland. These consisted of 116 samples of nine vegetables types including butterhead and iceberg lettuce, beetroot, white cabbage, carrot, cucumber, radish, tomato and potato collected between April and September 2011. Concentrations of nitrate and nitrite were determined by standard colorimetric methods used in Poland, with results expressed as mg per kg fresh weight of vegetables. Nitrate concentrations varied between 10 mg x kg(-1) to 4800 mg x kg(-1). The highest mean nitrate concentrations were found in radishes (2132 mgkg(-1)), butterhead lettuce (1725 mg x kg(-1)), beetroots (1306 mg x kg(-1)) and iceberg lettuce (890 mg x kg(-1)), whereas the lowest were found in cucumber (32 mg x kg(-1)) and tomato (35 mg x kg(-1)). Nitrite levels were also variable; the highest concentrations measured were in beetroot (mean 9.19 mg x kg(-1)) whilst much smaller amounts were present in carrot, cucumbers, iceberg lettuce, white cabbage, tomatoes and potatoes. The daily adult consumption of 100 g amounts of the studied vegetables were found not exceed the ADI for both nitrates and nitrites. Findings indicated the need for monitoring nitrate and nitrite content in radishes, butterhead lettuce and beetroot due to consumer health concerns.

  5. Researches concerning nitrates and nitrites accumulation in carrots, along of the vegetation stages

    Directory of Open Access Journals (Sweden)

    Monica NEGREA

    2008-05-01

    Full Text Available The presented paper deals with the determination of nitrates and nitrites content in carrots, in different vegetation stages of the carrot culture. High nitrates and nitrites concentration in vegetables is mainly due to excessive nitrogen content in the soil system, thus deteriorating the nutritional and hygienic values of products and complicating the processing and storage. The determination was tested on carrot samples assayed from an experimental field set up near Timisoara. In experimental field, to the carrot culture was administrated different doses of fertilizers (NPK and the samples for analysis were assayed in different phases of vegetation. The obtained results indicated that the highest level of nitrate in carrots was found to the variant b3 (N150P90K90 in experimental field, who was above maximum limit allowed (LMA. Maximum limit allowed for nitrates in carrots, in accordance with ORDER No. 293/640/2001-1/2002 regarding security and quality conditions for vegetables and fresh fruits for human consumption is 400 ppm. For all other samples of carrots the nitrates level was below of LMA. The nitrite content grows in case of fertilizer administration during the whole vegetation stages of the plant. In variant N150P90K90 the nitrite content was above (LMA in carrot samples in all stages of vegetation. The nitrite content in carrots should not exceed 1-2 ppm. Nitrate and nitrite content in carrots was done with the help of High Performance Liquid Chromatography (HPLC in the Laboratory for the Measurement of Residues of the Department of Agro-techniques of the U.S.A-V.M.B in Timisoara.

  6. Dietary polyphenols generate nitric oxide from nitrite in the stomach and induce smooth muscle relaxation

    International Nuclear Information System (INIS)

    Rocha, Barbara S.; Gago, Bruno; Barbosa, Rui M.; Laranjinha, Joao

    2009-01-01

    Nitrite, considered a biological waste and toxic product, is being regarded as an important physiological molecule in nitric oxide (·NO) biochemistry. Because the interaction of dietary phenolic compounds and nitrite would be kinetically (due to the high concentrations achieved) and thermodynamically (on basis of the redox potentials) feasible in the stomach, we have studied the potential reduction of nitrite by polyphenols present in several dietary sources. By measuring the time courses of ·NO production in simulated gastric juice (pH 2), the efficiency of the compounds studied is as follows: Epicatechin-3-O-gallate > quercetin > procyanidin B8 dimer > oleuropein > procyanidin B2 dimer > chlorogenic acid > epicatechin > catechin > procyanidin B5 dimer. The initial rates of ·NO production fall in a narrow range (ca. 1-5 μM s -1 ) but the distinct kinetics of the decay of ·NO signals suggest that competition reactions for ·NO are operative. The proof of concept that, in the presence of nitrite, phenol-containing dietary products induce a strong increase of ·NO in the stomach was established in an in vivo experiment with healthy volunteers consuming lettuce, onions, apples, wine, tea, berries and cherries. Moreover, selected mixtures of oleuropein and catechin with low nitrite (1 μM) were shown to induce muscle relaxation of stomach strips in a structure-dependent way. Data presented here brings strong support to the concept that polyphenols consumed in a variety of dietary products, under gastric conditions, reduce nitrite to ·NO that, in turn, may exert a biological impact as a local relaxant.

  7. Reactions of nitrite with hemoglobin measured by membrane inlet mass spectrometry

    Science.gov (United States)

    Tu, Chingkuang; Mikulski, Rose; Swenson, Erik R.; Silverman, David N.

    2010-01-01

    Membrane inlet mass spectrometry was used to observe nitric oxide in the well-studied reaction of nitrite with hemoglobin. The membrane inlet was submerged in the reaction solutions and measured NO in solution via its flux across a semipermeable membrane leading to the mass spectrometer detecting the mass-to-charge ratio m/z 30. This method measures NO directly in solution and is an alternate approach compared with methods that purge solutions to measure NO. Addition to deoxy-Hb(FeII) (near 38 µM heme concentration) of nitrite in a range of 80 µM to 16 mM showed no accumulation of either NO or N2O3 on a physiologically relevant time scale with a sensitivity near 1 nM. The addition of nitrite to oxy-Hb(FeII) and met-Hb(FeIII) did not accumulate free NO to appreciable extents. These observations show that for several minutes after mixing nitrite with hemoglogin, free NO does not accumulate to levels exceeding the equilibrium level of NO. The presence of cyanide ions did not alter the appearance of the data; however, the presence of 2 mM mercuric ions at the beginning of the experiment with deoxy-Hb(FeII) shortened the initial phase of NO accumulation and increased the maximal level of free, unbound NO by about twofold. These experiments appear consistent with no role of met-Hb(FeIII) in the generation of NO and an increase in nitrite reductase activity caused by the presumed binding of mercuric to cysteine residues. These results raise questions about the ability of reduction of nitrite mediated by deoxy-Hb(FeII) to play a role in vasodilation. PMID:18848984

  8. Safer and healthier reduced nitrites turkey meat sausages using lyophilized Cystoseira barbata seaweed extract.

    Science.gov (United States)

    Sellimi, Sabrine; Benslima, Abdelkarim; Ksouda, Ghada; Montero, Veronique Barragan; Hajji, Mohamed; Nasri, Moncef

    2017-10-21

    Background Nitrite salts are still common additives in the meat industry. The present study provides a first approach on the employment of the lyophilized aqueous extract (WE) of the Tunisian seaweed Cystoseira barbata for the quality enhancement of turkey meat sausage. Methods WE was supplemented as a natural antioxidant agent to investigate its effectiveness in delaying lipid oxidation turkey meat sausages containing reduced amounts of sodium nitrites. Results On storage day 5, all concentrations of WE (0.01-0.4 %) reduced the meat lipid oxidation by approximately 36 %, as compared to the negative control containing only 80 mg/kg of meat of sodium nitrites as antioxidant. It was noted that within 15 days of refrigerated storage, a meat system containing 80 mg/kg of meat of sodium nitrites and 0.02 % and 0.04 % of WE had similar Thiobarbituric Acid Reactive Substances (TBARS) levels (19±1.32 and 17±1.12 µmol/kg of meat, respectively), which were comparable to the positive control containing sodium nitrites (150 mg/kg of meat) and 0.045 % vitamin C (18.46±1.27 µmol/kg of meat). In-depth, the metabolomic profiling using gas chromatography-mass spectrometry (GC/MS) and liquid chromatography-quadripole-time-of-flight-mass spectrometry (LC-QTOF-MS) analyses of the Tunisian seaweed C. barbata solvent extracts showed that the main active compounds were phenolic compounds, fatty acids and sterols. Conclusions Overall, the cold medium containing C. barbata lyophilized aqueous extrac, with strong antioxidant activity and antihypertensive properties, may open the way to the development of a natural quality enhancement strategy for new functional and ever healthier reduced nitrites meat sausages based on algae.

  9. The stress caused by nitrite with titanium dioxide nanoparticles under UVA irradiation in human keratinocyte cell

    International Nuclear Information System (INIS)

    Tu, Min; Huang, Yi; Li, Hai-Ling; Gao, Zhong-Hong

    2012-01-01

    Highlights: ► Nitrite increased photo-toxicity of nano-TiO 2 on human keratinocyte cells in a dose-dependant manner. ► Morphological study suggested the cell death may be mediated by apoptosis inducing factor. ► Protein nitration was generated in the cells, and the most abundant nitrated protein was identified as cystatin-A. ► Tyr35 was the most likely site to be nitrated in cystatin-A. -- Abstract: Our previous work found that in the presence of nitrite, titanium dioxide nanoparticles can cause protein tyrosine nitration under UVA irradiation in vivo. In this paper, the human keratinocyte cells was used as a skin cell model to further study the photo-toxicity of titanium dioxide nanoparticles when nitrite was present. The results showed that nitrite increased the photo-toxicity of titanium dioxide in a dose-dependant manner, and generated protein tyrosine nitration in keratinocyte cells. Morphological study of keratinocyte cells suggested a specific apoptosis mediated by apoptosis inducing factor. It was also found the main target nitrated in cells was cystatin-A, which expressed abundantly in cytoplasm and functioned as a cysteine protease inhibitor. The stress induced by titanium dioxide with nitrite under UVA irradiation in human keratinocyte cells appeared to trigger the apoptosis inducing factor mediated cell death and lose the inhibition of active caspase by cystatin-A. We conclude that nitrite can bring new damage and stress to human keratinocyte cells with titanium dioxide nanoparticles under UVA irradiation.

  10. Co-treatment with conjugated linoleic acid and nitrite protects against myocardial infarction

    Directory of Open Access Journals (Sweden)

    Natia Qipshidze-Kelm

    2014-01-01

    Full Text Available According to the CDC, the most common type of heart disease is coronary artery disease, which commonly leads to myocardial infarction (MI. Therapeutic approaches to lessen the resulting cardiovascular injury associated with MI are limited. Recently, MicroRNAs (miRNAs have been shown to act as negative regulators of gene expression by inhibiting mRNA translation and/or stimulating mRNA degradation. A single miRNA can modulate physiological or disease phenotypes by regulating whole functional systems. Importantly, miRNAs can regulate cardiac function, thereby modulating heart muscle contraction, heart growth and morphogenesis. MicroRNA-499 (miRNA-499 is a cardiac-specific miRNA that when elevated causes cardiomyocyte hypertrophy, in turn preventing cardiac dysfunction during MI. Previous studies revealed that combination treatment with conjugated linoleic acid (cLA and nitrite preserved cardiovascular function in mice. Therefore, it was hypothesized that cLA and nitrite may regulate miRNA-499, thus providing cardiac protection during MI. To test this hypothesis, 12-week old mice were treated with cLA (10 mg/kg/d-via osmotic mini-pump or cLA and nitrite (50 ppm-drinking water 3 days prior to MI (ligation of the left anterior descending artery. Echocardiography and pressure–volume (PV-loop analysis revealed that cLA and nitrite-treated MI mice had improved heart function (10 days following MI compared to untreated MI mice. Treatment with cLA and nitrite significantly induced levels of miRNA-499 compared to untreated MI mice. In addition, treatment with cLA and nitrite abolished MI-induced protein expression of p53 and dynamin-related protein-1 (DRP-1. Moreover, the antioxidant enzyme expression of heme oxygenase-1 (HO-1 was elevated in MI mice treated with cLA and nitrite compared to untreated MI mice. Confocal imaging on heart tissue confirmed expression the levels of HO-1 and p53. Taken together, these results suggest that therapeutic

  11. Expanded metabolic versatility of ubiquitous nitrite-oxidizing bacteria from the genus Nitrospira

    DEFF Research Database (Denmark)

    Koch, Hanna; Lücker, Sebastian; Albertsen, Mads

    2015-01-01

    , we identified ecophysiological traits that contribute to the ecological success of Nitrospira. Unexpectedly, N. moscoviensis possesses genes coding for a urease and cleaves urea to ammonia and CO2. Ureolysis was not observed yet in nitrite oxidizers and enables N. moscoviensis to supply ammonia...... oxidizers lacking urease with ammonia from urea, which is fully nitrified by this consortium through reciprocal feeding. The presence of highly similar urease genes in Nitrospira lenta from activated sludge, in metagenomes from soils and freshwater habitats, and of other ureases in marine nitrite oxidizers...

  12. Aggregate Size and Architecture Determine Microbial Activity Balance for One-Stage Partial Nitritation and Anammox

    DEFF Research Database (Denmark)

    Vlaeminck, S.E.; Terada, Akihiko; Smets, Barth F.

    2010-01-01

    by the anoxic nitrite consumption rate. The smallest reactor A, B, and C aggregates were nitrite sources (NARR, > 1.7). Large reactor A and C aggregates were granules capable of autonomous nitrogen removal (NARR, 0.6 to 1.1) with internal AnAOB zones surrounded by an AerAOB rim. Around 50% of the autotrophic......AOB-rich aggregates (reactors B and C). The hypothesized granulation pathways include granule replication by division and budding and are driven by growth and/or decay based on species-specific physiology and by hydrodynamic shear and mixing....

  13. Chemical perspectives on alkali and earth alkaline nitrate and nitrite salts for concentrated solar power applications

    Energy Technology Data Exchange (ETDEWEB)

    Cordaro, Joseph G. [Sandia National Labsoratories, Livermore, CA (United States)

    2013-04-01

    Molten salts have been widely considered as the leading candidate heat transfer fluids (HTF) used in high temperature, concentrated solar power plants. Specifically, nitrate and nitrite based salts have been investigated as a HTF and even deployed in pilot plants generating up to 19.9 MW of electricity at operating temperatures above 500 C. New plant designs requiring higher operating temperatures for better efficiencies are pushing the stability limit of HTF. This paper presents an overview of the thermophysical properties of nitrate and nitrite salts and discusses thermodynamic and kinetic stability limitations as they relate to concentrated solar power generation. (orig.)

  14. Allosteric control of internal electron transfer in cytochrome cd1 nitrite reductase

    DEFF Research Database (Denmark)

    Farver, Ole; Kroneck, Peter M H; Zumft, Walter G

    2003-01-01

    Cytochrome cd1 nitrite reductase is a bifunctional multiheme enzyme catalyzing the one-electron reduction of nitrite to nitric oxide and the four-electron reduction of dioxygen to water. Kinetics and thermodynamics of the internal electron transfer process in the Pseudomonas stutzeri enzyme have...... been studied and found to be dominated by pronounced interactions between the c and the d1 hemes. The interactions are expressed both in dramatic changes in the internal electron-transfer rates between these sites and in marked cooperativity in their electron affinity. The results constitute a prime...... example of intraprotein control of the electron-transfer rates by allosteric interactions....

  15. Nitrite: A physiological store of nitric oxide and modulator of mitochondrial function

    Directory of Open Access Journals (Sweden)

    Sruti Shiva

    2013-01-01

    Full Text Available Nitrite, long considered a biologically inert metabolite of nitric oxide (NO oxidation, is now accepted as a physiological storage pool of NO that can be reduced to bioactive NO in hypoxic conditions to mediate a spectrum of physiological responses in blood and tissue. This graphical review will provide a broad overview of the role of nitrite in physiology, focusing on its formation and reduction to NO as well as its regulation of the mitochondrion—an emerging subcellular target for its biological actions in tissues.

  16. The steady-state kinetics of the NADH-dependent nitrite reductase from Escherichia coli K 12. Nitrite and hydroxylamine reduction.

    OpenAIRE

    Jackson, R H; Cole, J A; Cornish-Bowden, A

    1981-01-01

    The reduction of both NO2- and hydroxylamine by the NADH-dependent nitrite reductase of Escherichia coli K 12 (EC 1.6.6.4) appears to follow Michaelis-Menten kinetics over a wide range of NADH concentrations. Substrate inhibition can, however, be detected at low concentrations of the product NAD+. In addition, NAD+ displays mixed product inhibition with respect to NADH and mixed or uncompetitive inhibition with respect to hydroxylamine. These inhibition characteristics are consistent with a m...

  17. Aldehyde-Selective Wacker-Type Oxidation of Unbiased Alkenes Enabled by a Nitrite Co-Catalyst

    KAUST Repository

    Wickens, Zachary K.; Morandi, Bill; Grubbs, Robert H.

    2013-01-01

    Breaking the rules: Reversal of the high Markovnikov selectivity of Wacker-type oxidations was accomplished using a nitrite co-catalyst. Unbiased aliphatic alkenes can be oxidized with high yield and aldehyde selectivity, and several functional groups are tolerated. 18O-labeling experiments indicate that the aldehydic O atom is derived from the nitrite salt.

  18. Pancreatic cancer and exposure to dietary nitrate and nitrite in the NIH-AARP Diet and Health Study.

    Science.gov (United States)

    Aschebrook-Kilfoy, Briseis; Cross, Amanda J; Stolzenberg-Solomon, Rachael Z; Schatzkin, Arthur; Hollenbeck, Albert R; Sinha, Rashmi; Ward, Mary H

    2011-08-01

    Nitrate and nitrite are precursors of N-nitroso compounds, which induce tumors of the pancreas in animals. The authors evaluated the relation of dietary nitrate and nitrite to pancreatic cancer risk in the NIH-AARP Diet and Health Study. Nitrate and nitrite intakes were assessed at baseline using a 124-item food frequency questionnaire. During approximately 10 years of follow-up between 1995 and 2006, 1,728 incident pancreatic cancer cases were identified. There was no association between total nitrate or nitrite intake and pancreatic cancer in men or women. However, men in the highest quintile of summed nitrate/nitrite intake from processed meat had a nonsignificantly elevated risk of pancreatic cancer (hazard ratio = 1.18, 95% confidence interval: 0.95, 1.47; P-trend = 0.11). The authors observed a stronger increase in risk among men for nitrate/nitrite intake from processed meat at ages 12-13 years (highest quintile vs. lowest: hazard ratio = 1.32, 95% confidence interval: 0.99, 1.76; P-trend = 0.11), though the relation did not achieve statistical significance. The authors found no associations between adult or adolescent nitrate or nitrite intake from processed meats and pancreatic cancer among women. These results provide modest evidence that processed meat sources of dietary nitrate and nitrite may be associated with pancreatic cancer among men and provide no support for the hypothesis in women.

  19. The acclimation of Chlorella to high-level nitrite for potential application in biological NOx removal from industrial flue gases.

    Science.gov (United States)

    Li, Tianpei; Xu, Gang; Rong, Junfeng; Chen, Hui; He, Chenliu; Giordano, Mario; Wang, Qiang

    2016-05-20

    Nitrogen oxides (NOx) are the components of fossil flue gas that give rise to the greatest environmental concerns. This study evaluated the ability of the green algae Chlorella to acclimate to high level of NOx and the potential utilization of Chlorella strains in biological NOx removal (DeNOx) from industrial flue gases. Fifteen Chlorella strains were subject to high-level of nitrite (HN, 176.5 mmolL(-1) nitrite) to simulate exposure to high NOx. These strains were subsequently divided into four groups with respect to their ability to tolerate nitrite (excellent, good, fair, and poor). One strain from each group was selected to evaluate their photosynthetic response to HN condition, and the nitrite adaptability of the four Chlorella strains were further identified by using chlorophyll fluorescence. The outcome of our experiments shows that, although high concentrations of nitrite overall negatively affect growth and photosynthesis of Chlorella strains, the degree of nitrite tolerance is a strain-specific feature. Some Chlorella strains have an appreciably higher ability to acclimate to high-level of nitrite. Acclimation is achieved through a three-step process of restrict, acclimate, and thriving. Notably, Chlorella sp. C2 was found to have a high tolerance and to rapidly acclimate to high concentrations of nitrite; it is therefore a promising candidate for microalgae-based biological NOx removal. Copyright © 2016 Elsevier GmbH. All rights reserved.

  20. NarK is a nitrite-extrusion system involved in anaerobic nitrate respiration by Escherichia coli

    NARCIS (Netherlands)

    Rowe, John J.; Ubbink-Kok, Trees; Molenaar, Douwe; Konings, Wilhelmus; Driessen, Arnold J.M.

    Escherichia coli can use nitrate as a terminal electron acceptor for anaerobic respiration. A polytopic membrane protein, termed NarK, has been implicated in nitrate uptake and nitrite excretion and is thought to function as a nitrate/nitrite antiporter. The longest-lived radioactive isotope of

  1. Aldehyde-Selective Wacker-Type Oxidation of Unbiased Alkenes Enabled by a Nitrite Co-Catalyst

    KAUST Repository

    Wickens, Zachary K.

    2013-09-13

    Breaking the rules: Reversal of the high Markovnikov selectivity of Wacker-type oxidations was accomplished using a nitrite co-catalyst. Unbiased aliphatic alkenes can be oxidized with high yield and aldehyde selectivity, and several functional groups are tolerated. 18O-labeling experiments indicate that the aldehydic O atom is derived from the nitrite salt.

  2. Evaluation of the nitrite and leukocyte esterase activity tests for the diagnosis of acute symptomatic urinary tract infection in men.

    NARCIS (Netherlands)

    Koeijers, J.J.; Kessels, A.G.H.; Nys, S.; Bartelds, A.; Donker, G.; Stobberingh, E.; Verbon, A.

    2007-01-01

    For 422 male patients with symptoms indicative of a urinary tract infection, nitrite and leukocyte esterase activity dipstick test results were compared with results of culture of urine samples. The positive predictive value of a positive nitrite test result was 96%. Addition of results of the

  3. Electro-oxidation nitrite based on copper calcined layered double hydroxide and gold nanoparticles modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Cui Lin; Meng Xiaomeng; Xu Minrong; Shang Kun [College of Chemistry and Material Science, Shandong Agricultural University, Taian 271018, Shandong (China); Ai Shiyun, E-mail: ashy@sdau.edu.cn [College of Chemistry and Material Science, Shandong Agricultural University, Taian 271018, Shandong (China); Liu Yinping [College of Chemistry and Material Science, Shandong Agricultural University, Taian 271018, Shandong (China)

    2011-11-30

    Highlights: > A nitrite sensor fabricated based on copper calcined layered double hydroxides and gold nanoparticles modified electrode. > This sensor exhibited excellent electrocatalytic oxidation to nitrite. > This nitrite sensor exhibited very good analytical performance with low cost, convenient preparation and rapid detection. - Abstract: In this paper, a novel nitrite sensor was constructed based on electrodeposition of gold nanoparticles (AuNPs) on a copper calcined layered double hydroxide (Cu-CLDH) modified glassy carbon electrode. Electrochemical experiments showed that AuNPs/CLDH composite film exhibited excellent electrocatalytic oxidation activity with nitrite due to the synergistic effect of the Cu-CLDH with AuNPs. The fabricated sensor exhibited excellent performance for nitrite detection within a wide concentration interval of 1-191 {mu}M and with a detection limit of 0.5 {mu}M. The superior electrocatalytic response to nitrite was mainly attributed to the large surface area, minimized diffusion resistance, and enhanced electron transfer of the Cu-CLDH and AuNPs composition film. This platform offers a novel route for nitrite sensing with wide analytical applications and will supply the practical applications for a variety of simple, robust, and easy-to-manufacture analytical approaches in the future.

  4. Electro-oxidation nitrite based on copper calcined layered double hydroxide and gold nanoparticles modified glassy carbon electrode

    International Nuclear Information System (INIS)

    Cui Lin; Meng Xiaomeng; Xu Minrong; Shang Kun; Ai Shiyun; Liu Yinping

    2011-01-01

    Highlights: → A nitrite sensor fabricated based on copper calcined layered double hydroxides and gold nanoparticles modified electrode. → This sensor exhibited excellent electrocatalytic oxidation to nitrite. → This nitrite sensor exhibited very good analytical performance with low cost, convenient preparation and rapid detection. - Abstract: In this paper, a novel nitrite sensor was constructed based on electrodeposition of gold nanoparticles (AuNPs) on a copper calcined layered double hydroxide (Cu-CLDH) modified glassy carbon electrode. Electrochemical experiments showed that AuNPs/CLDH composite film exhibited excellent electrocatalytic oxidation activity with nitrite due to the synergistic effect of the Cu-CLDH with AuNPs. The fabricated sensor exhibited excellent performance for nitrite detection within a wide concentration interval of 1-191 μM and with a detection limit of 0.5 μM. The superior electrocatalytic response to nitrite was mainly attributed to the large surface area, minimized diffusion resistance, and enhanced electron transfer of the Cu-CLDH and AuNPs composition film. This platform offers a novel route for nitrite sensing with wide analytical applications and will supply the practical applications for a variety of simple, robust, and easy-to-manufacture analytical approaches in the future.

  5. Calcium, essential for health

    Science.gov (United States)

    Martínez de Victoria, Emilio

    2016-07-12

    Calcium (Ca) is the most abundant mineral element in our body. It accounts for about 2% of body weight. The functions of calcium are: a) functions skeletal and b) regulatory functions. Bone consists of a protein matrix that mineralizes mainly with calcium (the most abundant), phosphate and magnesium, for it is essential an adequate dietary intake of Ca, phosphorus and vitamin D. The ionic Ca (Ca2+) is essential to maintain and / or perform different specialized functions of, virtually, all body cells cellular. Because of its important functions Ca2+ must be closely regulated, keeping plasma concentrations within narrow ranges. For this reason there is an accurate response against hypocalcemia or hypercalcemia in which the parathormone, calcitriol, calcitonin and vitamin K are involved. Ca intakes in the Spanish population are low in a significant percentage of the older adult’s population, especially in women. The main source of Ca in the diet is milk and milk derivatives. Green leafy vegetables, fruits and legumes can be important sources of Ca in a Mediterranean dietary pattern. The bioavailability of dietary Ca depends on physiological and dietary factors. Physiological include age, physiological status (gestation and lactation) Ca and vitamin D status and disease. Several studies relate Ca intake in the diet and various diseases, such as osteoporosis, cancer, cardiovascular disease and obesity.

  6. Models of calcium signalling

    CERN Document Server

    Dupont, Geneviève; Kirk, Vivien; Sneyd, James

    2016-01-01

    This book discusses the ways in which mathematical, computational, and modelling methods can be used to help understand the dynamics of intracellular calcium. The concentration of free intracellular calcium is vital for controlling a wide range of cellular processes, and is thus of great physiological importance. However, because of the complex ways in which the calcium concentration varies, it is also of great mathematical interest.This book presents the general modelling theory as well as a large number of specific case examples, to show how mathematical modelling can interact with experimental approaches, in an interdisciplinary and multifaceted approach to the study of an important physiological control mechanism. Geneviève Dupont is FNRS Research Director at the Unit of Theoretical Chronobiology of the Université Libre de Bruxelles;Martin Falcke is head of the Mathematical Cell Physiology group at the Max Delbrück Center for Molecular Medicine, Berlin;Vivien Kirk is an Associate Professor in the Depar...

  7. Determination of five abused drugs in nitrite-adulterated urine by immunoassays and gas chromatography-mass spectrometry.

    Science.gov (United States)

    Tsai, S C; ElSohly, M A; Dubrovsky, T; Twarowska, B; Towt, J; Salamone, S J

    1998-10-01

    The adulteration of urine specimens with nitrite ion hasseen shown to mask the gas chromatography-mass spectrometry (GC-MS) confirmation testing of marijuana use. This study was designed to further investigate the effect of nitrite adulteration on the detection of five commonly abused drugs by immunoassay screening and GC-MS analysis. The drugs tested are cocaine metabolite (benzoylecgonine), morphine, 11-nor-delta-tetrahydrocannabinol-9-carboxylic acid (THCCOOH), amphetamine, and phencyclidine. The immunoassays evaluated included the instrument-based Abuscreen ONLINE assays, the on-site Abuscreen ONTRAK assays, and the one-step ONTRAK TESTCUP-5 assay. Multianalyte standards containing various levels of drugs were used to test the influence of both potassium and sodium nitrite. In the ONLINE immunoassays, the presence of up to 1.0M nitrite in the multianalyte standards had no significant effect for benzoylecgonine, morphine, and phencyclidine assays. With a high concentration of nitrite, ONLINE became more sensitive for amphetamine (detected more drug than what was expected) and less sensitive for THCCOOH (detected less drug than what was expected). No effects of nitrite were observed on the results of the Abuscreen ONTRAK assays. Similarly, no effects were observed on the absolute qualitative results of the TESTCUP-5 when testing the nitrite-adulterated standards. However, the produced intensities of the signals that indicate the negative test results were slightly lowered in the THC and phencyclidine assays. The presence of 1.0M of nitrite did not show dramatic interference with the GC-MS analysis of benzoylecgonine, morphine, amphetamine, and phencyclidine. In contrast, nitrite ion significantly interfered with the detection of THCCOOH by GC-MS. The presence of 0.03M of nitrite ion resulted in significant loss in the recovery of THCCOOH and its internal standard by GC-MS. The problem of nitrite adulteration could be alleviated by sodium bisulfite treatment even

  8. Biogenic amine formation and nitrite reactions in meat batter as affected by high-pressure processing and chilled storage.

    Science.gov (United States)

    Ruiz-Capillas, C; Aller-Guiote, P; Carballo, J; Colmenero, F Jiménez

    2006-12-27

    Changes in biogenic amine formation and nitrite depletion in meat batters as affected by pressure-temperature combinations (300 MPa/30 min/7, 20, and 40 degrees C), cooking process (70 degrees C/30 min), and storage (54 days/2 degrees C) were studied. Changes in residual nitrite concentration in raw meat batters were conditioned by the temperature and not by the pressure applied. Cooking process decreased (P nitrite concentration in all samples. High-pressure processing and cooking treatment increased (P nitrite concentration decreased with pressure processing, no effect was observed with the heating process of meat batters. High-pressure processing conditions had no effect on the rate of residual nitrite loss throughout the storage. The application of high pressure decreased (P processing conditions, generally, throughout storage biogenic amine levels did not change or increased, although quantitatively this effect was not very important.

  9. Production and mitigation of N2O in sequentially membrane-aerated redox-stratified nitritation/anammox biofilms

    DEFF Research Database (Denmark)

    Smets, Barth F.; Pellicer i Nàcher, Carles; Thamdrup, Bo

    batch incubations with biofilm samples revealed a significant N2O assimilatory activity. Anoxic incubations with N-15 enriched nitrite, nitrate, or ammonium, in presence or absence of acetate revealed the following: a very high conversion of original nitrite or nitrate N to N2O over N2, no stimulatory......Combining partial nitritation with anaerobic ammonium oxidation maybe a cost- and energy-efficient alternative to remove reduced nitrogen from nitrogen rich waste streams. However, increased N2O emissions (upto several % of the incoming N flux) have been observed for reactors performing partial...... nitritation, which is likely due to the stimulatory effect of combined elevated nitrite and ammonium concentrations and reduced oxygen concentrations on nitrous oxide formation by ammonium oxidizing bacteria. Because increased N2O emission may be inherent to partial nitrification systems, we have explored how...

  10. Determination of percent calcium carbonate in calcium chromate

    International Nuclear Information System (INIS)

    Middleton, H.W.

    1979-01-01

    The precision, accuracy and reliability of the macro-combustion method is superior to the Knorr alkalimetric method, and it is faster. It also significantly reduces the calcium chromate waste accrual problem. The macro-combustion method has been adopted as the official method for determination of percent calcium carbonate in thermal battery grade anhydrous calcium chromate and percent calcium carbonate in quicklime used in the production of calcium chromate. The apparatus and procedure can be used to measure the percent carbonate in inorganic materials other than calcium chromate. With simple modifications in the basic apparatus and procedure, the percent carbon and hydrogen can be measured in many organic material, including polymers and polymeric formulations. 5 figures, 5 tables

  11. Calcium oxalate stone and gout.

    Science.gov (United States)

    Marickar, Y M Fazil

    2009-12-01

    Gout is well known to be produced by increased uric acid level in blood. The objective of this paper is to assess the relationship between gout and calcium oxalate stone formation in the humans. 48 patients with combination of gout and calcium oxalate stone problem were included. The biochemical values of this group were compared with 38 randomly selected uric acid stone patients with gout, 43 stone patients with gout alone, 100 calcium oxalate stone patients without gout and 30 controls, making a total of 259 patients. Various biochemical parameters, namely serum calcium, phosphorus and uric acid and 24-h urine calcium, phosphorus, uric acid, oxalate, citrate and magnesium were analysed. ANOVA and Duncan's multiple-range tests were performed to assess statistical significance of the variations. The promoters of stone formation, namely serum calcium (P stone patients and gouty calcium oxalate stone patients compared to the non-gouty patients and controls. Urine oxalate (P stones patients. The inhibitor urine citrate (P stone gouty patients, followed by the gouty uric acid stone formers and gouty calcium oxalate stone patients. The high values of promoters, namely uric acid and calcium in the gouty stone patients indicate the tendency for urinary stone formation in the gouty stone patients. There is probably a correlation between gout and calcium oxalate urinary stone. We presume this mechanism is achieved through the uric acid metabolism. The findings point to the summation effect of metabolic changes in development of stone disease.

  12. Calcium Signaling in Taste Cells

    Science.gov (United States)

    Medler, Kathryn F.

    2014-01-01

    The sense of taste is a common ability shared by all organisms and is used to detect nutrients as well as potentially harmful compounds. Thus taste is critical to survival. Despite its importance, surprisingly little is known about the mechanisms generating and regulating responses to taste stimuli. All taste responses depend on calcium signals to generate appropriate responses which are relayed to the brain. Some taste cells have conventional synapses and rely on calcium influx through voltage-gated calcium channels. Other taste cells lack these synapses and depend on calcium release to formulate an output signal through a hemichannel. Beyond establishing these characteristics, few studies have focused on understanding how these calcium signals are formed. We identified multiple calcium clearance mechanisms that regulate calcium levels in taste cells as well as a calcium influx that contributes to maintaining appropriate calcium homeostasis in these cells. Multiple factors regulate the evoked taste signals with varying roles in different cell populations. Clearly, calcium signaling is a dynamic process in taste cells and is more complex than has previously been appreciated. PMID:25450977

  13. FIA-Spectrophotometric Method for Determination of Nitrite in Meat Products: An Experiment Exploring Color Reduction of an Azo-Compound

    Science.gov (United States)

    Penteado, Jose C.; Angnes, Lucio; Masini, Jorge C.; Oliveira, Paulo C. C.

    2005-01-01

    This article describes the reaction between nitrite and safranine O. This sensitive reaction is based on the disappearance of color of the reddish-orange azo dye, allowing the determination of nitrite at the mg mL-1 level. A factorial optimization of parameters was carried out and the method was applied for the quantification of nitrite in…

  14. Impact of temperature on ammonium and nitrite removal rates in RAS moving bed biofilters

    DEFF Research Database (Denmark)

    Kinyage, John Peter Hewa; Pedersen, Lars-Flemming

    2016-01-01

    The impact of temperature on bacterial processes is well known; however temperature related data on nitrification rates in aquaculture systems are fragmented and compiled from different studies. We sought to determine ammonium and nitrite removal kinetics over a temperature range from 6 to 36 °C...

  15. Flow injection determination of metronidazole through spectrophotometric measurement of the nitrite ion produced upon alkaline hydrolysis

    Directory of Open Access Journals (Sweden)

    Simões Simone S.

    2006-01-01

    Full Text Available A new method for metronidazole determination, based on spectrometric monitoring of a diazonium salt produced in-line by alkaline hydrolysis released nitrite ions, was developed and successfully applied to pharmaceutical tablets (r = 0.9993, 2.0-20.0 mg L-1, DL = 0.7 mg L-1 with no interference from common ingredients accompanying the drug.

  16. Simultaneous Voltammetric/Amperometric Determination of Sulfide and Nitrite in Water at BDD Electrode

    Directory of Open Access Journals (Sweden)

    Anamaria Baciu

    2015-06-01

    Full Text Available This work reported new voltammetric/amperometric-based protocols using a commercial boron-doped diamond (BDD electrode for simple and fast simultaneous detection of sulfide and nitrite from water. Square-wave voltammetry operated under the optimized working conditions of 0.01 V step potential, 0.5 V modulation amplitude and 10 Hz frequency allowed achieving the best electroanalytical parameters for the simultaneous detection of nitrite and sulfide. For practical in-field detection applications, the multiple-pulsed amperometry technique was operated under optimized conditions, i.e., −0.5 V/SCE for a duration of 0.3 s as conditioning step, +0.85 V/SCE for a duration of 3 s that assure the sulfide oxidation and +1.25 V/SCE for a duration of 0.3 s, where the nitrite oxidation occurred, which allowed the simultaneously detection of sulfide and nitrite without interference between them. Good accuracy was found for this protocol in comparison with standardized methods for each anion. Also, no interference effect was found for the cation and anion species, which are common in the water matrix.

  17. MUTAGENICITY OF NITRITE-TREATED AQUEOUS EXTRACT OF 'PIPER BETLE'; L

    Science.gov (United States)

    Betel quid is chewed as a masticatory material by people in certain areas of Asia. The quid chewing has been related to oral cancer by epidemiological study. The mutagenic components in the aqueous extracts of betel quid ingredients were studied. Only nitrite-treated aqueous extr...

  18. Exhaled breath condensate nitrates, but not nitrites or FENO, relate to asthma control.

    Science.gov (United States)

    Malinovschi, Andrei; Pizzimenti, Stefano; Sciascia, Savino; Heffler, Enrico; Badiu, Iuliana; Rolla, Giovanni

    2011-07-01

    Asthma is a chronic respiratory disease, characterised by airways inflammation, obstruction and hyperresponsiveness. Asthma control is the goal of asthma treatment, but many patients have sub-optimal control. Exhaled NO and exhaled breath condensate (EBC) NO metabolites (nitrites and nitrates) measurements are non-invasive tools to assess airways inflammation. Our aim was to investigate the relationships between asthma control and the above-named biomarkers of airways inflammation. Thirty-nine non-smoking asthmatic patients (19 women) aged 50 (21-80) years performed measurements of exhaled NO (FENO), EBC nitrates, nitrites and pH, and answered Asthma Control Questionnaire (ACQ) and Asthma Control Test (ACT)-questionnaire. The ACT and ACQ score were strongly interrelated (ρ = -0.84, p 0.05). EBC nitrates were negatively related to ACT score (ρ = -0.34, p = 0.03) and positively related to ACQ score (ρ = 0.41, p = 0.001) while no relation of EBC nitrites to either ACQ or ACT score was found (p>0.05). EBC nitrates were the only biomarker that was significantly related to asthma control. This suggests that nitrates, but not nitrites or FENO, reflect an aspect of airways inflammation that is closer related to asthma symptoms. Therefore there is a potential role for EBC nitrates in objective assessment of asthma control. Copyright © 2010 Elsevier Ltd. All rights reserved.

  19. Effect of Electrolytes on the Adsorption of Nitrite and Nitrate from ...

    African Journals Online (AJOL)

    Michael Horsfall

    presence of alkaline salts (Na3PO4, CH3COONa; 95.5 per cent) and neutral chloride salts (NaCl, MgCl2; 90.4 per cent) compared to ... The charcoal was freed off its residual nitrite and ..... separation factor, Rl, over the test concentrations have.

  20. Major role of nitrite-oxidizing bacteria in dark ocean carbon fixation

    NARCIS (Netherlands)

    Pachiadaki, M.G.; Sintes, E.; Bergauer, K.; Brown, J.M.; Record, N.R.; Swan, B.K.; Mathyer, M.E.; Hallam, S.J.; López-Garcìa, P.; Takaki, Y.; Nunoura, T.; Woyke, T.; Herndl, G.J.; Stepanauskas, R.

    2017-01-01

    Carbon fixation by chemoautotrophic microorganisms in the dark ocean has a major impact on global carbon cycling and ecological relationships in the ocean’s interior, but the relevant taxa and energy sources remain enigmatic.We show evidence that nitrite-oxidizing bacteria affiliated with the

  1. Intake of nitrate and nitrite and the risk of gastric cancer: A prospective cohort study

    NARCIS (Netherlands)

    Loon, A.J.M. van; Botterweck, A.A.M.; Goldbohm, R.A.; Brants, H.A.M.; Klaveren, J.D. van; Brandt, P.A. van den

    1998-01-01

    The association between the intake of nitrate or nitrite and gastric cancer risk was investigated in a prospective cohort study started in 1986 in the Netherlands, of 120,852 men and women aged 55-69 years. At baseline, data on dietary intake, smoking habits and other covariates were collected by

  2. Nitrate and nitrite in the diet: how to assess their benefit and risk for human health.

    Science.gov (United States)

    Habermeyer, Michael; Roth, Angelika; Guth, Sabine; Diel, Patrick; Engel, Karl-Heinz; Epe, Bernd; Fürst, Peter; Heinz, Volker; Humpf, Hans-Ulrich; Joost, Hans-Georg; Knorr, Dietrich; de Kok, Theo; Kulling, Sabine; Lampen, Alfonso; Marko, Doris; Rechkemmer, Gerhard; Rietjens, Ivonne; Stadler, Richard H; Vieths, Stefan; Vogel, Rudi; Steinberg, Pablo; Eisenbrand, Gerhard

    2015-01-01

    Nitrate is a natural constituent of the human diet and an approved food additive. It can be partially converted to nitrogen monoxide, which induces vasodilation and thereby decreases blood pressure. This effect is associated with a reduced risk regarding cardiovascular disease, myocardial infarction, and stroke. Moreover, dietary nitrate has been associated with beneficial effects in patients with gastric ulcer, renal failure, or metabolic syndrome. Recent studies indicate that such beneficial health effects due to dietary nitrate may be achievable at intake levels resulting from the daily consumption of nitrate-rich vegetables. N-nitroso compounds are endogenously formed in humans. However, their relevance for human health has not been adequately explored up to now. Nitrate and nitrite are per se not carcinogenic, but under conditions that result in endogenous nitrosation, it cannot be excluded that ingested nitrate and nitrite may lead to an increased cancer risk and may probably be carcinogenic to humans. In this review, the known beneficial and detrimental health effects related to dietary nitrate/nitrite intake are described and the identified gaps in knowledge as well as the research needs required to perform a reliable benefit/risk assessment in terms of long-term human health consequences due to dietary nitrate/nitrite intake are presented. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Nitrite promotes protein carbonylation and Strecker aldehyde formation in experimental fermented sausages: are both events connected?

    Science.gov (United States)

    Villaverde, A; Ventanas, J; Estévez, M

    2014-12-01

    The role played by curing agents (nitrite, ascorbate) on protein oxidation and Strecker aldehyde formation is studied. To fulfill this objective, increasing concentrations of nitrite (0, 75 and 150ppm) and ascorbate (0, 250 and 500ppm) were added to sausages subjected to a 54day drying process. The concurrence of intense proteolysis, protein carbonylation and formation of Strecker aldehydes during processing of sausages suggests that α-aminoadipic semialdehyde (AAS) and γ-glutamic semialdehyde (GGS) may be implicated in the formation of Strecker aldehydes. The fact that nitrite (150ppm, ingoing amount) significantly promoted the formation of protein carbonyls at early stages of processing and the subsequent formation of Strecker aldehydes provides strength to this hypothesis. Ascorbate (125 and 250ppm) controlled the overall extent of protein carbonylation in sausages without declining the formation of Strecker aldehydes. These results may contribute to understanding the chemistry fundamentals of the positive influence of nitrite on the flavor and overall acceptability of cured muscle foods. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Determination of Nitrite and Nitrate in Natural Waters Using Flow Injection with Spectrophotometric Detection

    International Nuclear Information System (INIS)

    Yaqoob, M.; Nabi, A.

    2013-01-01

    A simple and sensitive flow injection spectrophotometric method is reported for the room temperature determination of nitrite and nitrate based on the Griess reaction and a copperised cadmium column for reduction of nitrate. Calibration graphs were linear over the range 2 - 1000 micro g N L /sup -1/ (R2 = 0.9997 and 0.9999, n = 9) with a limit of detection (3 s.d.) of 1.0 micro g N L and relative standard deviations (n = 10) of 0.9 and 1.2% for 50 micro g N L nitrite and nitrate respectively. The sample throughput was 50 h. The effect of reagent concentrations, physical parameters (flow rate, sample volume, reaction coil and copperised cadmium column length) and the potential interferences are reported. The effect of salinity on the blank and on the determination of nitrite and nitrate are also presented. The method was applied to natural waters (rainwater, freshwater and estuarine water) and the results for nitrite + nitrate (140 - 7310 micro g N L/sup -1/) were not significantly different (95% confidence interval) from results obtained using a segmented flow analyser reference method with spectrophotometric detection. (author)

  5. Molecular underpinnings of nitrite effect on CymA-dependent respiration in Shewanella oneidensis

    Directory of Open Access Journals (Sweden)

    Miao Jin

    2016-07-01

    Full Text Available Shewanella exhibit a remarkable versatility of respiration, with a diverse array of electron acceptors (EAs. In environments where these bacteria thrive, multiple EAs are usually present. However, we know little about strategies by which these EAs and their interaction affect ecophysiology of Shewanella. In this study, we demonstrate in the model strain, Shewanella oneidensis MR-1, that nitrite, not through nitric oxide to which it may convert, inhibits respiration of fumarate, and probably many other EAs whose reduction depends on quinol dehydrogenase CymA. This is achieved via the repression of cyclic adenosine monophosphate (cAMP production, a second messenger required for activation of cAMP-receptor protein (Crp which plays a primary role in regulation of respiration. If nitrite is not promptly removed, intracellular cAMP levels drop, and this impairs Crp activity. As a result, the production of nitrite reductase NrfA, CymA, and fumarate reductase FccA is substantially reduced. In contrast, nitrite can be simultaneously respired with trimethylamine N-oxide, resulting in enhanced biomass.

  6. [Research on Cultivation and Stability of Nitritation Granular Sludge in Integrated ABR-CSTR Reactor].

    Science.gov (United States)

    Wu, Kai-cheng; Wu, Peng; Shen, Yao-liang; Li, Yue-han; Wang, Han-fang; Xu, Yue-zhong

    2015-11-01

    Abstract: The last two compartments of the Anaerobic Baffled Readtor ( ABR) were altered into aeration tank and sedimentation tank respectively to get an integrated anaerobic-aerobic reactor, using anaerobic granular sludge in anaerobic zone and aerobic granular sludge in aerobic zone as seed sludge. The research explored the condition to cultivate nitritation granular sludge, under the condition of continuous flow. The C/N rate was decreased from 1 to 0.4 and the ammonia nitrogen volumetric loading rate was increased from 0.89 kg x ( m3 x d)(-1) to 2.23 kg x (m3 x d)(-1) while the setting time of 1 h was controlled in the aerobic zone. After the system was operated for 45 days, the mature nitritation granular sludge in aerobic zone showed a compact structure and yellow color while the nitrite accumulation rate was about 80% in the effluent. The associated inhibition of free ammonia (FA) and free nitrous acid (FNA) dominated the nitritation. Part of granules lost stability during the initial period of operation and flocs appeared in the aerobic zone. However, the flocs were transformed into newly generated small particles in the following reactor operation, demonstrating that organic carbon was benefit to granulation and the enrichment of slow-growing nitrifying played an important role in the stability of granules.

  7. Spectrophotometric determination of nitrite by its catalytic effect on the oxidation of congo red with bromate

    Directory of Open Access Journals (Sweden)

    Zenovia Moldovan

    2012-08-01

    Full Text Available A novel simple, sensitive and rapid kinetic-spectrophotometric method for the determination of trace amounts of nitrite is proposed. The method is based on its catalytic effect on the oxidation of congo red (CR by potassium bromate in acidic solution. The oxidation reaction is monitored spectrophotometrically by measuring the decrease in the absorbance of CR at a suitable λmax = 570 nm for the first 10–40 s from the start of the reaction. Under the optimum experimental conditions (sulfuric acid, 0.3 M; CR, 0.75Χ10-4 M; potassium bromate, 5Χ10-4 M and 25 oC, nitrite can be determined in the range of 0.015–0.75 µg mL−1 with the detection limit of 0.006 µg mL−1. The relative standard deviation of five replicate determination of 0.25 µg mL−1 nitrite was 2.5%. The proposed method was applied satisfactorily to the determination of nitrite in spiked drinking water samples.DOI: http://dx.doi.org/10.4314/bcse.v26i2.1

  8. Comparative surface electrochemistry of Co and Co3O4 nanoparticles: nitrite as an analytical probe

    CSIR Research Space (South Africa)

    Adekunle, AS

    2010-12-01

    Full Text Available (CV) and electrochemical impedance spectroscopy (EIS). The EPPGE-Co demonstrated enhanced electron transport and catalytic efficiency towards nitrite oxidation at pH 7.4 compared with the other electrodes studied. The catalytic rate constant (K...

  9. Nitrate, nitrite, and nitrous oxide transformations in sediments along a salinity gradient in the Weser Estuary

    DEFF Research Database (Denmark)

    Nielsen, Michael; Gieseke, Armin; de Beer, Dirk

    2009-01-01

    by activity of nitrite oxidisers in oxic surface layers. In contrast, high rates of NO2- release occurred in marine sediment, where NO2- production was predominantly associated with incomplete nitrification in oxic layers. Similarly, stimulated partial nitrification due to NH4+ addition led to NO2- liberation...

  10. Biosensor for laboratory and lander-based analysis of benthicnitrate plus nitrite distribution in marine environments

    DEFF Research Database (Denmark)

    Revsbech, N. P.; Glud, Ronnie Nøhr

    2009-01-01

    We present a psychotropic bacteria–based biosensor that can be used in low–temperature seawater for the analysis of nitrate + nitrite (NOx –). The sensor can be used to resolve concentrations below 1 µmol L–1 at low temperature (

  11. Potential rates of ammonium oxidation, nitrite oxidation, nitrate reduction and denitrification in the young barley rhizosphere

    DEFF Research Database (Denmark)

    Højberg, Ole; Binnerup, S. J.; Sørensen, Jan

    1996-01-01

    Potential activities (enzyme contents) of ammonium (NH4+) oxidizing, nitrite (NO2-) oxidizing, nitrate (NO3-) reducing and denitrifying bacteria were measured in bulk and rhizosphere soil obtained from young barley plants in the field. The activities as well as pools of inorganic N (NH4+, NO2...

  12. Effects of Lactic Acid Bacteria on Residual Nitrite in a Summer Style Sausage.

    Science.gov (United States)

    1984-01-01

    Lactobacillus plantarum 4008 Lactobacillus bulgaricus 11842 Lactobacillus fermentum 9338 Lactobacillus casei subsp. rhamnosus 7469 Pediococcus acidilactici...the American Type Culture Collection Culture ATCC Number Lactobacillus acidophilus 4365 0 Lactobacillus casei E393 Lactobacillus leichmannii 4797...sources (e.g., Micrococcus varians, Lactobacillus plantarum) exhibited different nitrite reducing abilities. Lactobacillus leichmannii (

  13. Selective Reduction of Nitrite to Nitrogen with Carbon-Supported Pd-AOT Nanoparticles

    NARCIS (Netherlands)

    Perez-Coronado, A. M.; Calvo, L.; Baeza, J.A.; Palomar, J.; Lefferts, L.; Rodriguez, J-C.; Gilarranz, M.A.

    2017-01-01

    The catalytic reduction of nitrite in water with hydrogen has been studied using a new strategy to control selectivity. The catalysts used are based on size-controlled Pd-AOT nanoparticles, synthesized via sodium bis[2-ethylhexyl] sulfosuccinate (AOT)/isooctane reverse microemulsion, supported on

  14. Colorimetric determination of nitrate plus nitrite in water by enzymatic reduction, automated discrete analyzer methods

    Science.gov (United States)

    Patton, Charles J.; Kryskalla, Jennifer R.

    2011-01-01

    This report documents work at the U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL) to validate enzymatic reduction, colorimetric determinative methods for nitrate + nitrite in filtered water by automated discrete analysis. In these standard- and low-level methods (USGS I-2547-11 and I-2548-11), nitrate is reduced to nitrite with nontoxic, soluble nitrate reductase rather than toxic, granular, copperized cadmium used in the longstanding USGS automated continuous-flow analyzer methods I-2545-90 (NWQL laboratory code 1975) and I-2546-91 (NWQL laboratory code 1979). Colorimetric reagents used to determine resulting nitrite in aforementioned enzymatic- and cadmium-reduction methods are identical. The enzyme used in these discrete analyzer methods, designated AtNaR2 by its manufacturer, is produced by recombinant expression of the nitrate reductase gene from wall cress (Arabidopsis thaliana) in the yeast Pichia pastoris. Unlike other commercially available nitrate reductases we evaluated, AtNaR2 maintains high activity at 37°C and is not inhibited by high-phenolic-content humic acids at reaction temperatures in the range of 20°C to 37°C. These previously unrecognized AtNaR2 characteristics are essential for successful performance of discrete analyzer nitrate + nitrite assays (henceforth, DA-AtNaR2) described here.

  15. Nonthermal effect of microwave irradiation on nitrite uptake in Chlamydomonas reinhardtii

    International Nuclear Information System (INIS)

    Pedrajas, C.; Cotrino, J.

    1989-01-01

    When cells of the unicellular green alga Chlamydomonas reinhardtii were subjected to microwave irradiation at 2.45 GHz, nitrite uptake kinetics still obeyed the Michaelis-Menten equation, the Km of the process remaining constant, whereas V max increased, which indicates an enhanced nonthermal permeability in irradiated cells. (author)

  16. Hopanoid-producing bacteria in the Red Sea include the major marine nitrite-oxidizers

    KAUST Repository

    Kharbush, Jenan J

    2018-04-10

    Hopanoids, including the extended side chain-containing bacteriohopanepolyols (BHPs), are bacterial lipids found abundantly in the geological record and across Earth\\'s surface environments. However, the physiological roles of this biomarker remain uncertain, limiting interpretation of their presence in current and past environments. Recent work investigating the diversity and distribution of hopanoid producers in the marine environment implicated low-oxygen regions as important loci of hopanoid production, and data from marine oxygen minimum zones (OMZs) suggested that the dominant hopanoid producers in these environments are nitrite-utilizing organisms, revealing a potential connection between hopanoid production and the marine nitrogen cycle. Here we use metagenomic data from the Red Sea to investigate the ecology of hopanoid producers in an environmental setting that is biogeochemically distinct from those investigated previously. The distributions of hopanoid production and nitrite oxidation genes in the Red Sea are closely correlated, and the majority of hopanoid producers are taxonomically affiliated with the major marine nitrite oxidizers, Nitrospinae and Nitrospirae. These results suggest that the relationship between hopanoid production and nitrite oxidation is conserved across varying biogeochemical conditions in dark ocean microbial ecosystems.

  17. IRIS Assessment Plan for Nitrate and Nitrite (Scoping and Problem Formulation Materials)

    Science.gov (United States)

    In September 2017, EPA released the draft IRIS Assessment Plan (IAP) for Nitrate and Nitrite for public review and comment. This document was discussed at an EPA Science Advisory Board (SAB) Chemical Assessment Advisory Committee (CAAC) meeting on September 27-28, 2017....

  18. Anaerobic Oxidation of Methane Coupled to Nitrite Reduction by Halophilic Marine NC10 Bacteria.

    Science.gov (United States)

    He, Zhanfei; Geng, Sha; Cai, Chaoyang; Liu, Shuai; Liu, Yan; Pan, Yawei; Lou, Liping; Zheng, Ping; Xu, Xinhua; Hu, Baolan

    2015-08-15

    Anaerobic oxidation of methane (AOM) coupled to nitrite reduction is a novel AOM process that is mediated by denitrifying methanotrophs. To date, enrichments of these denitrifying methanotrophs have been confined to freshwater systems; however, the recent findings of 16S rRNA and pmoA gene sequences in marine sediments suggest a possible occurrence of AOM coupled to nitrite reduction in marine systems. In this research, a marine denitrifying methanotrophic culture was obtained after 20 months of enrichment. Activity testing and quantitative PCR (qPCR) analysis were then conducted and showed that the methane oxidation activity and the number of NC10 bacteria increased correlatively during the enrichment period. 16S rRNA gene sequencing indicated that only bacteria in group A of the NC10 phylum were enriched and responsible for the resulting methane oxidation activity, although a diverse community of NC10 bacteria was harbored in the inoculum. Fluorescence in situ hybridization showed that NC10 bacteria were dominant in the enrichment culture after 20 months. The effect of salinity on the marine denitrifying methanotrophic culture was investigated, and the apparent optimal salinity was 20.5‰, which suggested that halophilic bacterial AOM coupled to nitrite reduction was obtained. Moreover, the apparent substrate affinity coefficients of the halophilic denitrifying methanotrophs were determined to be 9.8 ± 2.2 μM for methane and 8.7 ± 1.5 μM for nitrite. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  19. Bioelectrode-based approach for enhancing nitrate and nitrite removal and electricity generation from eutrophic lakes

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    2012-01-01

    Nitrate and nitrite contamination of surface waters (e.g. lakes) has become a severe environmental and health problem, especially in developing countries. The recent demonstration of nitrate reduction at the cathode of microbial fuel cell (MFC) provides an opportunity to develop a new technology ...

  20. Hopanoid-producing bacteria in the Red Sea include the major marine nitrite-oxidizers

    KAUST Repository

    Kharbush, Jenan J; Thompson, Luke R; Haroon, Mohamed; Knight, Rob; Aluwihare, Lihini I

    2018-01-01

    Hopanoids, including the extended side chain-containing bacteriohopanepolyols (BHPs), are bacterial lipids found abundantly in the geological record and across Earth's surface environments. However, the physiological roles of this biomarker remain uncertain, limiting interpretation of their presence in current and past environments. Recent work investigating the diversity and distribution of hopanoid producers in the marine environment implicated low-oxygen regions as important loci of hopanoid production, and data from marine oxygen minimum zones (OMZs) suggested that the dominant hopanoid producers in these environments are nitrite-utilizing organisms, revealing a potential connection between hopanoid production and the marine nitrogen cycle. Here we use metagenomic data from the Red Sea to investigate the ecology of hopanoid producers in an environmental setting that is biogeochemically distinct from those investigated previously. The distributions of hopanoid production and nitrite oxidation genes in the Red Sea are closely correlated, and the majority of hopanoid producers are taxonomically affiliated with the major marine nitrite oxidizers, Nitrospinae and Nitrospirae. These results suggest that the relationship between hopanoid production and nitrite oxidation is conserved across varying biogeochemical conditions in dark ocean microbial ecosystems.

  1. Noble metal catalyzed hydrogen generation from formic acid in nitrite-containing simulated nuclear waste media

    International Nuclear Information System (INIS)

    King, R.B.; Bhattacharyya, N.K.; Wiemers, K.D.

    1994-08-01

    Simulants for the Hanford Waste Vitrification Plant (HWVP) feed containing the major non-radioactive components Al, Cd, Fe, Mn, Nd, Ni, Si, Zr, Na, CO 3 2- , NO 3 -, and NO 2 - were used as media to evaluate the stability of formic acid towards hydrogen evolution by the reaction HCO 2 H → H 2 + CO 2 catalyzed by the noble metals Ru, Rh, and/or Pd found in significant quantities in uranium fission products. Small scale experiments using 40-50 mL of feed simulant in closed glass reactors (250-550 mL total volume) at 80-100 degree C were used to study the effect of nitrite and nitrate ion on the catalytic activities of the noble metals for formic acid decomposition. Reactions were monitored using gas chromatography to analyze the CO 2 , H 2 , NO, and N 2 O in the gas phase as a function of time. Rhodium, which was introduced as soluble RhCl 3 ·3H 2 O, was found to be the most active catalyst for hydrogen generation from formic acid above ∼80 degree C in the presence of nitrite ion in accord with earlier observations. The inherent homogeneous nature of the nitrite-promoted Rh-catalyzed formic acid decomposition is suggested by the approximate pseudo first-order dependence of the hydrogen production rate on Rh concentration. Titration of the typical feed simulants containing carbonate and nitrite with formic acid in the presence of rhodium at the reaction temperature (∼90 degree C) indicates that the nitrite-promoted Rh-catalyzed decomposition of formic acid occurs only after formic acid has reacted with all of the carbonate and nitrite present to form CO 2 and NO/N 2 O, respectively. The catalytic activities of Ru and Pd towards hydrogen generation from formic acid are quite different than those of Rh in that they are inhibited rather than promoted by the presence of nitrite ion

  2. Cardiovascular Effects of Calcium Supplements

    Directory of Open Access Journals (Sweden)

    Ian R. Reid

    2013-07-01

    Full Text Available Calcium supplements reduce bone turnover and slow the rate of bone loss. However, few studies have demonstrated reduced fracture incidence with calcium supplements, and meta-analyses show only a 10% decrease in fractures, which is of borderline statistical and clinical significance. Trials in normal older women and in patients with renal impairment suggest that calcium supplements increase the risk of cardiovascular disease. To further assess their safety, we recently conducted a meta-analysis of trials of calcium supplements, and found a 27%–31% increase in risk of myocardial infarction, and a 12%–20% increase in risk of stroke. These findings are robust because they are based on pre-specified analyses of randomized, placebo-controlled trials and are consistent across the trials. Co-administration of vitamin D with calcium does not lessen these adverse effects. The increased cardiovascular risk with calcium supplements is consistent with epidemiological data relating higher circulating calcium concentrations to cardiovascular disease in normal populations. There are several possible pathophysiological mechanisms for these effects, including effects on vascular calcification, vascular cells, blood coagulation and calcium-sensing receptors. Thus, the non-skeletal risks of calcium supplements appear to outweigh any skeletal benefits, and are they appear to be unnecessary for the efficacy of other osteoporosis treatments.

  3. PENURUNAN KADAR AMONIA, NITRIT, DAN NITRAT LIMBAH CAIR INDUSTRI TAHU MENGGUNAKAN ARANG AKTIF DARI AMPAS KOPI

    Directory of Open Access Journals (Sweden)

    Irmanto

    2009-11-01

    Full Text Available The tofu industry is one of food industry which the product of organic waste to environment pollution. One of alternative methode which used to overcome tofu industrial waste water pollution is adsorption methode using activated carbon from coffee waste. The aim of this researched is to know about the activated carbon from coffee waste quality which observe of rendemen, water content, ash content, and iodium adsorption, to know optimum contact of time and pH of coffee waste to decrease ammonia, nitrite and nitrate contents in tofu industry waste water and to know decrease percentage of ammonia, nitrite and nitrate contents in tofu industrial waste water using activated carbon from coffee waste. The activated carbon made by soaking of coffee waste in HCl 0.1 M solution for 2 days. The activated carbon coaled in muffle furnace at temperature 350°C. The activated carbon analyzed consist of rendemen, water content, ash content, and iodium adsorption. Optimum contact of time and pH of coffee waste determined in order to get optimum adsorption ammonia, nitrite and nitrate in tofu industrial waste water. Contact time variation are 1, 10, 30, 45, 60, 90, 120 minutes and pH variation are 4, 5, 6, 7, 8, 9, 10. The result showed that the activated carbon from coffee waste fulfill the criteria SNI number 06-3730-1995. The activated carbon from coffee waste could be used to decrease the ammonia, nitrite, and nitrate contents in tofu industrial waste water at the optimum contact of time of 30 minutes and pH 7. Decreasing percentage of ammonia, nitrite and nitrate contents in tofu industrial waste water are 64,69% , 52,35% and 86,40% respectively.

  4. A novel marine nitrite-oxidizing Nitrospira species from Dutch coastal North Sea water

    Directory of Open Access Journals (Sweden)

    Suzanne Caroline Marianne Haaijer

    2013-03-01

    Full Text Available Marine microorganisms are important for the global nitrogen cycle, but marine nitrifiers, especially aerobic nitrite-oxidizers, remain largely unexplored. To increase the number of cultured representatives of marine nitrite-oxidizing bacteria (NOB, a bioreactor cultivation approach was adopted to first enrich nitrifiers and ultimately nitrite oxidizers from Dutch coastal North Sea water. With solely ammonia as the substrate an active nitrifiying community consisting of novel marine Nitrosomonas aerobic ammonia oxidizers (AOB and Nitrospina and Nitrospira NOB was obtained which converted a maximum of 2 mmoles of ammonia per liter per day. Switching the feed of the culture to nitrite as a sole substrate resulted in a Nitrospira NOB dominated community (approximately 80% of the total microbial community based on FISH and metagenomic data converting a maximum of 3 mmoles of nitrite per liter per day. Phylogenetic analyses based on the 16S rRNA gene indicated that the Nitrospira enriched from the North Sea is a novel Nitrospira species with Nitrospira marina as the next taxonomically described relative (94% 16S rRNA sequence identity. Transmission electron microscopy analysis revealed a cell plan typical for Nitrospira species. The cytoplasm contained electron light particles that might represent glycogen storage. A large periplasmic space was present which was filled with electron dense particles. Nitrospira-targeted PCR analyses demonstrated the presence of the enriched Nitrospira species in a time series of North Sea genomic DNA samples. The availability of this new Nitrospira species enrichment culture facilitates further in-depth studies such as determination of physiological constraints, and comparison to other NOB species.

  5. Dietary Nitrates, Nitrites, and Nitrosamines Intake and the Risk of Gastric Cancer: A Meta-Analysis

    Directory of Open Access Journals (Sweden)

    Peng Song

    2015-12-01

    Full Text Available The potential associations between dietary consumption of nitrates, nitrites, and nitrosamines and gastric cancer risk have been investigated by several studies, but yielded inconclusive results. We conducted a meta-analysis to provide a quantitative assessment of their relationships. Relevant articles were identified by a systematic literature searching of PubMed and Embase databases prior to August 2015. Random-effects models were employed to pool the relative risks. A total of 22 articles consisting of 49 studies—19 studies for nitrates, 19 studies for nitrites, and 11 studies for N-nitrosodimethylamine (NDMA—were included. The summary relative risk of stomach cancer for the highest categories, compared with the lowest, was 0.80 (95% confidence interval (CI, 0.69–0.93 for dietary nitrates intake, 1.31 (95% CI, 1.13–1.52 for nitrites, and 1.34 (95% CI, 1.02–1.76 for NDMA (p for heterogeneity was 0.015, 0.013 and <0.001, respectively. The study type was found as the main source of heterogeneity for nitrates and nitrites. The heterogeneity for NDMA could not be eliminated completely through stratified analysis. Although significant associations were all observed in case-control studies, the cohort studies still showed a slight trend. The dose-response analysis indicated similar results as well. High nitrates intake was associated with a weak but statistically significant reduced risk of gastric cancer. Whereas increased consumption of nitrites and NDMA seemed to be risk factors for cancer. Due to the lack of uniformity for exposure assessment across studies, further prospective researches are warranted to verify these findings.

  6. Dietary Nitrates, Nitrites, and Nitrosamines Intake and the Risk of Gastric Cancer: A Meta-Analysis.

    Science.gov (United States)

    Song, Peng; Wu, Lei; Guan, Wenxian

    2015-12-01

    The potential associations between dietary consumption of nitrates, nitrites, and nitrosamines and gastric cancer risk have been investigated by several studies, but yielded inconclusive results. We conducted a meta-analysis to provide a quantitative assessment of their relationships. Relevant articles were identified by a systematic literature searching of PubMed and Embase databases prior to August 2015. Random-effects models were employed to pool the relative risks. A total of 22 articles consisting of 49 studies-19 studies for nitrates, 19 studies for nitrites, and 11 studies for N-nitrosodimethylamine (NDMA)-were included. The summary relative risk of stomach cancer for the highest categories, compared with the lowest, was 0.80 (95% confidence interval (CI), 0.69-0.93) for dietary nitrates intake, 1.31 (95% CI, 1.13-1.52) for nitrites, and 1.34 (95% CI, 1.02-1.76) for NDMA (p for heterogeneity was 0.015, 0.013 and nitrates and nitrites. The heterogeneity for NDMA could not be eliminated completely through stratified analysis. Although significant associations were all observed in case-control studies, the cohort studies still showed a slight trend. The dose-response analysis indicated similar results as well. High nitrates intake was associated with a weak but statistically significant reduced risk of gastric cancer. Whereas increased consumption of nitrites and NDMA seemed to be risk factors for cancer. Due to the lack of uniformity for exposure assessment across studies, further prospective researches are warranted to verify these findings.

  7. Combined exposure to ambient UVB radiation and nitrite negatively affects survival of amphibian early life stages

    International Nuclear Information System (INIS)

    Macias, Guadalupe; Marco, Adolfo; Blaustein, Andrew R.

    2007-01-01

    Many aquatic species are sensitive to ambient levels of ultraviolet-B radiation (UVB) and chemical fertilizers. However, recent studies indicate that the interaction among multiple stressors acting simultaneously could be contributing to the population declines of some animal species. Therefore, we tested the potential synergistic effects between ambient levels of UVB and a contaminant, sodium nitrite in the larvae of two amphibian species, the common European toad Bufo bufo and the Iberian green frog Rana perezi. We studied R. perezi from both mountain and coastal populations to examine if populations of the same species varied in their response to stressors in different habitats. Both species were sensitive to the two stressors acting alone, but the interaction between the two stressors caused a multiplicative impact on tadpole survival. For B. bufo, the combination of UVB and nitrite was up to seven times more lethal than mortality for each stressor alone. In a coastal wetland, the combination of UVB and nitrite was four times more toxic for R. perezi than the sum of the effect on mortality for each stressor alone. One mg/L of nitrite killed half the population of R. perezi at Gredos Mountains at day 10 in the absence of UVB. In the presence of UVB, 50% of the tadpoles from the same experiment died at day 7. Similar toxic response were found for R. perezi in two highly contrasted environments suggesting this synergistic interaction can be a widespread phenomenon. The interaction of excess chemical fertilizers and manure with ambient UVB radiation could be contributing to the global decline of some amphibian species. We suggest that potential exposure to UVB radiation be accounted for when assessing water quality criteria regarding nitrite pollution

  8. Impact of hemoglobin nitrite to nitric oxide reductase on blood transfusion for resuscitation from hemorrhagic shock

    Directory of Open Access Journals (Sweden)

    Chad Brouse

    2015-01-01

    Full Text Available Background: Transfusion of blood remains the gold standard for fluid resuscitation from hemorrhagic shock. Hemoglobin (Hb within the red blood cell transports oxygen and modulates nitric oxide (NO through NO scavenging and nitrite reductase. Aims: This study was designed to examine the effects of incorporating a novel NO modulator, RRx-001, on systemic and microvascular hemodynamic response after blood transfusion for resuscitation from hemorrhagic shock in a hamster window chamber model. In addition, to RRx-001 the role of low dose of nitrite (1 × 10−9 moles per animal supplementation after resuscitation was studied. Materials and Methods: Severe hemorrhage was induced by arterial controlled bleeding of 50% of the blood volume (BV and the hypovolemic state was maintained for 1 h. The animals received volume resuscitation by an infusion of 25% of BV using fresh blood alone or with added nitrite, or fresh blood treated with RRx-001 (140 mg/kg or RRx-001 (140 mg/kg with added nitrite. Systemic and microvascular hemodynamics were followed at baseline and at different time points during the entire study. Tissue apoptosis and necrosis were measured 8 h after resuscitation to correlate hemodynamic changes with tissue viability. Results: Compared to resuscitation with blood alone, blood treated with RRx-001 decreased vascular resistance, increased blood flow and functional capillary density immediately after resuscitation and preserved tissue viability. Furthermore, in RRx-001 treated animals, both mean arterial pressure (MAP and met Hb were maintained within normal levels after resuscitation (MAP >90 mmHg and metHb <2%. The addition of nitrite to RRx-001 did not significantly improve the effects of RRx-001, as it increased methemoglobinemia and lower MAP. Conclusion: RRx-001 alone enhanced perfusion and reduced tissue damage as compared to blood; it may serve as an adjunct therapy to the current gold standard treatment for resuscitation from

  9. Nitrate uptake and nitrite release by tomato roots in response to anoxia.

    Science.gov (United States)

    Morard, Philippe; Silvestre, Jérôme; Lacoste, Ludovic; Caumes, Edith; Lamaze, Thierry

    2004-07-01

    Excised root systems of tomato plants (early fruiting stage, 2nd flush) were subjected to a gradual transition from normoxia to anoxia by seating the hydroponic root medium while aeration was stopped. Oxygen level in the medium and respiration rate decreased and reached very low values after 12 h of treatment, indicating that the tissues were anoxic thereafter. Nitrate loss from the nutrient solution was strongly stimulated by anoxia (after 26 h) concomitantly with a release of nitrite starting only after 16 h of treatment. This effect was not observed in the absence of roots or in the presence of tungstate, but occurred with whole plants or with sterile in vitro cultured root tissues. These results indicate that biochemical processes in the root involve nitrate reductase. NR activity assayed in tomato roots increased during anoxia. This phenomenon appeared in intact plants and in root tissues of detopped plants. The stimulating effect of oxygen deprivation on nitrate uptake was specific; anoxia simultaneously entailed a release of orthophosphate, sulfate, and potassium by the roots. Anoxia enhanced nitrate reduction by root tissues, and nitrite ions were released into xylem sap and into medium culture. In terms of the overall balance, the amount of nitrite recovered represented only half of the amount of nitrate utilized. Nitrite reduction into nitric oxide and perhaps into nitrogen gas could account for this discrepancy. These results appear to be the first report of an increase in nitrate uptake by plant roots under anoxia of tomato at the early fruiting stage, and the rates of nitrite release in nutrient medium by the asphyxiated roots are the fastest yet reported.

  10. Oxidative stress and nitrite dynamics under maximal load in elite athletes: relation to sport type.

    Science.gov (United States)

    Cubrilo, Dejan; Djordjevic, Dusica; Zivkovic, Vladimir; Djuric, Dragan; Blagojevic, Dusko; Spasic, Mihajlo; Jakovljevic, Vladimir

    2011-09-01

    Maximal workload in elite athletes induces increased generation of reactive oxygen/nitrogen species (RONS) and oxidative stress, but the dynamics of RONS production are not fully explored. The aim of our study was to examine the effects of long-term engagement in sports with different energy requirements (aerobic, anaerobic, and aerobic/anaerobic) on oxidative stress parameters during progressive exercise test. Concentrations of lactates, nitric oxide (NO) measured through stabile end product-nitrites (NO(2) (-)), superoxide anion radical (O(2) (•-)), and thiobarbituric reactive substances (TBARS) as index of lipid peroxidation were determined in rest, after maximal workload, and at 4 and 10th min of recovery in blood plasma of top level competitors in rowing, cycling, and taekwondo. Results showed that sportmen had similar concentrations of lactates and O(2) (•-) in rest. Nitrite concentrations in rest were the lowest in taekwondo fighters, while rowers had the highest levels among examined groups. The order of magnitude for TBARS level in the rest was bicycling > taekwondo > rowing. During exercise at maximal intensity, the concentration of lactate significantly elevated to similar levels in all tested sportsmen and they were persistently elevated during recovery period of 4 and 10 min. There were no significant changes in O(2) (•-), nitrite, and TBARS levels neither at the maximum intensity of exercise nor during the recovery period comparing to the rest period in examined individuals. Our results showed that long term different training strategies establish different basal nitrites and lipid peroxidation levels in sportmen. However, progressive exercise does not influence basal nitrite and oxidative stress parameters level neither at maximal load nor during the first 10 min of recovery in sportmen studied.

  11. Combined exposure to ambient UVB radiation and nitrite negatively affects survival of amphibian early life stages

    Energy Technology Data Exchange (ETDEWEB)

    Macias, Guadalupe [Donana Biological Station, CSIC, Spanish Council for Scientific Research. P.O. Box 1056, Sevilla 41013 (Spain); Marco, Adolfo [Donana Biological Station, CSIC, Spanish Council for Scientific Research. P.O. Box 1056, Sevilla 41013 (Spain)], E-mail: amarco@ebd.csic.es; Blaustein, Andrew R. [Department of Zoology, Oregon State University, Corvallis, Oregon, 97331 (United States)

    2007-10-15

    Many aquatic species are sensitive to ambient levels of ultraviolet-B radiation (UVB) and chemical fertilizers. However, recent studies indicate that the interaction among multiple stressors acting simultaneously could be contributing to the population declines of some animal species. Therefore, we tested the potential synergistic effects between ambient levels of UVB and a contaminant, sodium nitrite in the larvae of two amphibian species, the common European toad Bufo bufo and the Iberian green frog Rana perezi. We studied R. perezi from both mountain and coastal populations to examine if populations of the same species varied in their response to stressors in different habitats. Both species were sensitive to the two stressors acting alone, but the interaction between the two stressors caused a multiplicative impact on tadpole survival. For B. bufo, the combination of UVB and nitrite was up to seven times more lethal than mortality for each stressor alone. In a coastal wetland, the combination of UVB and nitrite was four times more toxic for R. perezi than the sum of the effect on mortality for each stressor alone. One mg/L of nitrite killed half the population of R. perezi at Gredos Mountains at day 10 in the absence of UVB. In the presence of UVB, 50% of the tadpoles from the same experiment died at day 7. Similar toxic response were found for R. perezi in two highly contrasted environments suggesting this synergistic interaction can be a widespread phenomenon. The interaction of excess chemical fertilizers and manure with ambient UVB radiation could be contributing to the global decline of some amphibian species. We suggest that potential exposure to UVB radiation be accounted for when assessing water quality criteria regarding nitrite pollution.

  12. Electrocatalytic reduction of nitrite on tetraruthenated metalloporphyrins/Nafion glassy carbon modified electrode

    Energy Technology Data Exchange (ETDEWEB)

    Calfuman, Karla [Facultad de Ciencias, Departamento de Quimica, Universidad de Chile, Las Palmeras 3425, Casilla 653, Nunoa, Santiago (Chile); Aguirre, Maria Jesus [Facultad de Quimica y Biologia, Departamento de Quimica de los Materiales, Universidad de Santiago de Chile, Santiago (Chile); Canete-Rosales, Paulina; Bollo, Soledad [Facultad de Ciencias Quimicas y Farmaceuticas, Departamento de Quimica Farmacologica y Toxicologica, Universidad de Chile, Santiago (Chile); Llusar, Rosa [Departamento de Quimica Fisica y Analitica, Universidad de Jaume I, Castellon (Spain); Isaacs, Mauricio, E-mail: misaacs@uchile.cl [Facultad de Ciencias, Departamento de Quimica, Universidad de Chile, Las Palmeras 3425, Casilla 653, Nunoa, Santiago (Chile)

    2011-10-01

    Highlights: > Preparation and characterization of modified electrodes with M(II) Tetraruthenated porphyrins onto a Nafion film. > The electrodes were characterized by SEM, TEM, AFM and SECM techniques. > The modified electrodes are active in the electrochemical reduction of nitrite at -660 mV vs Ag/AgCl. > GC/Nf/CoTRP modified electrode is more electrochemically active than their Ni and Zn analogues. - Abstract: This paper describes the electrochemical reduction of nitrite ion in neutral aqueous solution mediated by tetraruthenated metalloporphyrins (Co(II), Ni(II) and Zn(II)) electrostatically assembled onto a Nafion film previously adsorbed on glassy carbon or ITO electrodes. Scanning electron microscope (SEM-EDX) and transmission electron microscopy (TEM) results have shown that on ITO electrodes the macrocycles forms multiple layers with a disordered stacking orientation over the Nafion film occupying hydrophobic and hydrophilic sites in the polyelectrolyte. Atomic force microscopy (AFM) results demonstrated that the Nafion film is 35 nm thick and tetraruthenated metalloporphyrins layers 190 nm thick presenting a thin but compacted morphology. Scanning electrochemical microscopy (SECM) images shows that the Co(II) tetraruthenated porphyrins/Nf/GC modified electrode is more electrochemically active than their Ni and Zn analogues. These modified electrodes are able to reduce nitrite at -660 mV showing enhanced reduction current and a decrease in the required overpotential compared to bare glassy carbon electrode. Controlled potential electrolysis experiments verify the production of ammonia, hydrazine and hydroxylamine at potentials where reduction of solvent is plausible demonstrating some selectivity toward the nitrite ion. Rotating disc electrode voltammetry shows that the factor that governs the kinetics of nitrite reduction is the charge propagation in the film.

  13. SR calcium handling and calcium after-transients in a rabbit model of heart failure

    NARCIS (Netherlands)

    Baartscheer, Antonius; Schumacher, Cees A.; Belterman, Charly N. W.; Coronel, Ruben; Fiolet, Jan W. T.

    2003-01-01

    Objective: After-depolarization associated arrhythmias are frequently observed in heart failure and associated with spontaneous calcium release from sarcoplasmic reticulum (SR), calcium after-transients. We hypothesize that disturbed SR calcium handling underlies calcium after-transients in heart

  14. 21 CFR 573.240 - Calcium periodate.

    Science.gov (United States)

    2010-04-01

    ... with calcium hydroxide or calcium oxide to form a substance consisting of not less than 60 percent by... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium periodate. 573.240 Section 573.240 Food... Additive Listing § 573.240 Calcium periodate. The food additive calcium periodate may be safely used in...

  15. 21 CFR 573.260 - Calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium silicate. 573.260 Section 573.260 Food and... Listing § 573.260 Calcium silicate. Calcium silicate, including synthetic calcium silicate, may be safely used as an anticaking agent in animal feed, provided that the amount of calcium silicate does not...

  16. Increased hydrazine during partial nitritation process in upflow air-lift reactor fed with supernatant of anaerobic digester effluent

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jeongdong [University of Alberta, Alberta (Canada); Jung, Sokhee [Samsung SDS, Seoul (Korea, Republic of); Ahn, Young-Ho [Yeungnam University, Gyungsan (Korea, Republic of)

    2013-06-15

    The optimal balance of ammonium and nitrite is essential for successful operation of the subsequent anammox process. We conducted a partial nitritation experiment using an upflow air-lift reactor to provide operational parameters for achieving the optimal ratio of ammonium to nitrite, by feeding supernatant of anaerobic digester effluent, high-nitrogen containing rejection water. Semi-continuous operation results show that HRT should be set between 15 and 17 hours to achieve the optimum ration of 1.3 of NO{sub 2}-N/NH{sub 4}-N. In the UAR, nitritation was the dominant reaction due to high concentration of ammonia and low biodegradable organics. The influent contained low concentrations of hydroxylamine and hydrazine. However, hydrazine increased during partial nitritation by ⁓60-130% although there was no potential anammox activity in the reactor. The partial nitritation process successfully provided the ratio of nitrogen species for the anammox reaction, and relived the nitrite restraint on the anammox activity by increasing hydrazine concentration.

  17. Simultaneous determination of nitrite and nitrate residues in meat products marketed in Shiraz by high performance liquid chromatography

    Directory of Open Access Journals (Sweden)

    H Golkari

    2012-08-01

    Full Text Available Nitrite and nitrate are the key ingredients and play a multifunctional role in meat curing technology. Despite all of their desirable effects, the addition of nitrite to meat is the major cause of carcinogenic N-nitrosamines formation. In this study, the amount of residual nitrite and nitrate in meat products containing 61% to 80% meat were assessed. The samples were obtained at the fourth day of their production from Shiraz retails and analyzed using high performance liquid chromatography (HPLC. According to the results, the mean concentrations of residual nitrite and nitrate were estimated at 36.96 ± 7.38 and 85.81 ± 5.5 mg/kg in small-diameter (1.5-2 cm sausages. Meanwhile, in large-diameter (5.5-8 cm sausages the residues were estimated at 20.97 ± 3.28 and 124.85±5.3 mg/kg, respectively. In all analyzed samples, the residual nitrite level was found below the permitted level of 120 mg/kg which indicated the application of allowed concentrations of nitrite in such products. The mean values of residual nitrite and nitrate concentrations were statistically different (p

  18. Nigella sativa oil attenuates chronic nephrotoxicity induced by oral sodium nitrite: Effects on tissue fibrosis and apoptosis.

    Science.gov (United States)

    Al-Gayyar, Mohammed M H; Hassan, Hanan M; Alyoussef, Abdullah; Abbas, Ahmed; Darweish, Mohamed M; El-Hawwary, Amany A

    2016-03-01

    Sodium nitrite, a food preservative, has been reported to increase oxidative stress indicators such as lipid peroxidation, which can affect different organs including the kidney. Here, we investigated the toxic effects of oral sodium nitrite on kidney function in rats and evaluated potential protective effects of Nigella sativa oil (NSO). Seventy adult male Sprague-Dawley rats received 80 mg/kg sodium nitrite orally in the presence or absence of NSO (2.5, 5, and 10 ml/kg) for 12 weeks. Morphological changes were assessed by hematoxylin and eosin, Mallory trichome, and periodic acid-Schiff staining. Renal tissues were used for measurements of oxidative stress markers, C-reactive protein, cytochrome C oxidase, transforming growth factor (TGF)-beta1, monocyte chemotactic protein (MCP)-1, pJNK/JNK, and caspase-3. NSO significantly reduced sodium nitrite-induced elevation in serum urea and creatinine, as well as increasing normal appearance of renal tissue. NSO also prevented reductions in glycogen levels caused by sodium nitrite alone. Moreover, NSO treatment resulted in dose-dependent significant reductions in fibrosis markers after sodium nitrite-induced 3- and 2.7-fold increase in MCP-1 and TGF-beta1, respectively. Finally, NSO partially reduced the elevated caspase-3 and pJNK/JNK. NSO ameliorates sodium nitrite-induced nephrotoxicity through blocking oxidative stress, attenuation of fibrosis/inflammation, restoration of glycogen level, amelioration of cytochrome C oxidase, and inhibition of apoptosis.

  19. In vitro effect of sodium nitrite on platelet aggregation in human platelet rich plasma--preliminary report.

    Science.gov (United States)

    Kadan, M; Doğanci, S; Yildirim, V; Özgür, G; Erol, G; Karabacak, K; Avcu, F

    2015-10-01

    The role of nitrates and nitric oxide on platelet functions has obtained an increasing attention with respect to their potential effects on cardiovascular disorders. In this study we aimed to analyze the effect of sodium nitrite on platelet functions in human platelets. This in vitro study was designed to show the effect of sodium nitrite on platelet functions in seven healthy volunteers. Blood samples were centrifuged to prepare platelet rich plasma and platelet poor plasma. Platelet rich plasma was diluted with the platelet poor plasma to have a final count of 300,000 ± 25,000 platelets. Platelet rich plasma was incubated with six different increasing doses (from 10 μM to 5 mM) of sodium nitrite for 1 hour at 37°C. Then stimulating agents including collagen (3 μg ml-1), adenosine diphosphate (10 μM), and epinephrine (10 μM) were added to the cuvette. Changes in light transmission were observed for 10 minutes. In addition spontaneous aggregation were performed in control group with all aggregating agents separately. Effect of sodium nitrite on agonist-induced platelet aggregation depends on the concentration of sodium nitrite. Compared with control group, agonist-induced platelet aggregations were significantly suppressed by sodium nitrite at the concentration of 5, 1.0 and 0.5 mM. Our results suggested that sodium nitrite has inhibitory effects in vitro on platelet aggregation in a dose-dependent manner.

  20. 21 CFR 172.330 - Calcium pantothenate, calcium chloride double salt.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium pantothenate, calcium chloride double salt... FOOD FOR HUMAN CONSUMPTION Special Dietary and Nutritional Additives § 172.330 Calcium pantothenate, calcium chloride double salt. The food additive calcium chloride double salt of calcium pantothenate may...

  1. The Effects of Dietary Calcium and/or Iron Deficiency upon Murine Intestinal Calcium Binding Protein Activity and Calcium Absorption

    OpenAIRE

    McDonald, Catherine M.

    1980-01-01

    Iron deficiency has been shown to impair calcium absorption, leading to decreased bone mass. Vitamin D3-dependent calcium binding protein (CaBP) has been demonstrated to be necessary for the active transport of calcium in the intestine of numerous species. Iron deficiency might affect the activity of the calcium binding protein. Four experimental diets were formulated as follows: Diet 1, iron adequate, calcium adequate; Diet 2, iron deficient, calcium adequate; Diet 3, iron adequate, calci...

  2. Hemoglobin as a nitrite anhydrase: modeling methemoglobin-mediated N2O3 formation.

    Science.gov (United States)

    Hopmann, Kathrin H; Cardey, Bruno; Gladwin, Mark T; Kim-Shapiro, Daniel B; Ghosh, Abhik

    2011-05-27

    Nitrite has recently been recognized as a storage form of NO in blood and as playing a key role in hypoxic vasodilation. The nitrite ion is readily reduced to NO by hemoglobin in red blood cells, which, as it happens, also presents a conundrum. Given NO's enormous affinity for ferrous heme, a key question concerns how it escapes capture by hemoglobin as it diffuses out of the red cells and to the endothelium, where vasodilation takes place. Dinitrogen trioxide (N(2)O(3)) has been proposed as a vehicle that transports NO to the endothelium, where it dissociates to NO and NO(2). Although N(2)O(3) formation might be readily explained by the reaction Hb-Fe(3+)+NO(2)(-)+NO⇌Hb-Fe(2+)+N(2)O(3), the exact manner in which methemoglobin (Hb-Fe(3+)), nitrite and NO interact with one another is unclear. Both an "Hb-Fe(3+)-NO(2)(-)+NO" pathway and an "Hb-Fe(3+)-NO+NO(2)(-) " pathway have been proposed. Neither pathway has been established experimentally. Nor has there been any attempt until now to theoretically model N(2)O(3) formation, the so-called nitrite anhydrase reaction. Both pathways have been examined here in a detailed density functional theory (DFT, B3LYP/TZP) study and both have been found to be feasible based on energetics criteria. Modeling the "Hb-Fe(3+)-NO(2)(-)+NO" pathway proved complex. Not only are multiple linkage-isomeric (N- and O-coordinated) structures conceivable for methemoglobin-nitrite, multiple isomeric forms are also possible for N(2)O(3) (the lowest-energy state has an N-N-bonded nitronitrosyl structure, O(2)N-NO). We considered multiple spin states of methemoglobin-nitrite as well as ferromagnetic and antiferromagnetic coupling of the Fe(3+) and NO spins. Together, the isomerism and spin variables result in a diabolically complex combinatorial space of reaction pathways. Fortunately, transition states could be successfully calculated for the vast majority of these reaction channels, both M(S)=0 and M(S)=1. For a six-coordinate Fe(3+)-O

  3. Cooperative use of cytochrome cd1 nitrite reductase and its redox partner cytochrome c552 to improve the selectivity of nitrite biosensing

    International Nuclear Information System (INIS)

    Serra, A.S.; Jorge, S.R.; Silveira, C.M.; Moura, J.J.G.; Jubete, E.; Ochoteco, E.; Cabanero, G.; Grande, H.; Almeida, M.G.

    2011-01-01

    In this work, a novel enzymatic biosensor for determination of nitrites constructed on an electrochemical transducing platform is proposed. The sensor is based on cytochrome-cd 1 (cyt-cd 1 ) nitrite reductase from Marinobacter hydrocarbonoclasticus strain 617 as biological recognition element, and its putative physiological redox partner cytochrome-c 552 (cyt-c 552 ), as electron mediator. The proteins were co-immobilized using a photopolymerizable polyvinyl alcohol (PVA) derivative, onto carbon paste screen printed electrodes (CPSPEs); the optimal modification conditions were 100 μM cyt-cd 1 /100 μM cyt-c 552 and 50% PVA, after a 48 h polymerization time. Electrochemical characterization of the mediator was carried out by cyclic voltammetry. The one-electron exchange between cyt-c 552 and the working electrode is a quasi-reversible process, without mass transport limitations. The formal potential of the mediator is 254 ± 2 mV vs NHE and the intermolecular electron transfer rate constant between cytochromes c 552 and cd 1 is 9.9 x 10 3 M -1 s -1 . The analytical parameters of the biosensor response to nitrite as assessed by amperometric measurements were: linear range from 10 to 200 μM; detection and quantification limits of 7 and 24 μM, respectively; sensitivity of 2.49 ± 0.08 A mol -1 cm 2 μM -1 . Catalytic profiles in the presence of possible interfering species were also investigated. The interference from competitive enzymatic reduction of dissolved oxygen could be overcome by tuning the cyclic voltammograms for faster sweep rates.

  4. Cooperative use of cytochrome cd{sub 1} nitrite reductase and its redox partner cytochrome c{sub 552} to improve the selectivity of nitrite biosensing

    Energy Technology Data Exchange (ETDEWEB)

    Serra, A.S.; Jorge, S.R.; Silveira, C.M.; Moura, J.J.G. [REQUIMTE - Dept. de Quimica, CQFB, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Jubete, E.; Ochoteco, E.; Cabanero, G.; Grande, H. [CIDETEC - Centro de Tecnologias Electroquimicas, Parque Tecnologico de San Sebastian, Po Miramon, 196, 20009 Donostia - San Sebastian (Spain); Almeida, M.G., E-mail: mga@dq.fct.unl.pt [REQUIMTE - Dept. de Quimica, CQFB, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Escola Superior de Saude Egas Moniz, Monte de Caparica, 2829-511 Caparica (Portugal)

    2011-05-05

    In this work, a novel enzymatic biosensor for determination of nitrites constructed on an electrochemical transducing platform is proposed. The sensor is based on cytochrome-cd{sub 1} (cyt-cd{sub 1}) nitrite reductase from Marinobacter hydrocarbonoclasticus strain 617 as biological recognition element, and its putative physiological redox partner cytochrome-c{sub 552} (cyt-c{sub 552}), as electron mediator. The proteins were co-immobilized using a photopolymerizable polyvinyl alcohol (PVA) derivative, onto carbon paste screen printed electrodes (CPSPEs); the optimal modification conditions were 100 {mu}M cyt-cd{sub 1}/100 {mu}M cyt-c{sub 552} and 50% PVA, after a 48 h polymerization time. Electrochemical characterization of the mediator was carried out by cyclic voltammetry. The one-electron exchange between cyt-c{sub 552} and the working electrode is a quasi-reversible process, without mass transport limitations. The formal potential of the mediator is 254 {+-} 2 mV vs NHE and the intermolecular electron transfer rate constant between cytochromes c{sub 552} and cd{sub 1} is 9.9 x 10{sup 3} M{sup -1} s{sup -1}. The analytical parameters of the biosensor response to nitrite as assessed by amperometric measurements were: linear range from 10 to 200 {mu}M; detection and quantification limits of 7 and 24 {mu}M, respectively; sensitivity of 2.49 {+-} 0.08 A mol{sup -1} cm{sup 2} {mu}M{sup -1}. Catalytic profiles in the presence of possible interfering species were also investigated. The interference from competitive enzymatic reduction of dissolved oxygen could be overcome by tuning the cyclic voltammograms for faster sweep rates.

  5. Generation of nitric oxide from nitrite by carbonic anhydrase: a possible link between metabolic activity and vasodilation

    DEFF Research Database (Denmark)

    Aamand, Rasmus; Dalsgaard, Thomas; Jensen, Frank Bo

    2009-01-01

    In catalyzing the reversible hydration of CO2 to bicarbonate and protons, the ubiquitous enzyme carbonic anhydrase (CA) plays a crucial role in CO2 transport, in acid-base balance, and in linking local acidosis to O2 unloading from hemoglobin. Considering the structural similarity between...... bicarbonate and nitrite, we hypothesized that CA uses nitrite as a substrate to produce the potent vasodilator nitric oxide (NO) to increase local blood flow to metabolically active tissues. Here we show that CA readily reacts with nitrite to generate NO, particularly at low pH, and that the NO produced...

  6. Calcium, vitamin D, and your bones

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000490.htm Calcium, vitamin D, and your bones To use the sharing ... and maintain strong bones. How Much Calcium and Vitamin D do I Need? Amounts of calcium are ...

  7. Calcium Supplements: Do Men Need Them Too?

    Science.gov (United States)

    ... Lifestyle Nutrition and healthy eating Should men take calcium supplements? Answers from Katherine Zeratsky, R.D., L. ... Most healthy men don't need to take calcium supplements. Calcium is important for men for optimal ...

  8. Calcium transport in turtle bladder

    International Nuclear Information System (INIS)

    Sabatini, S.; Kurtzman, N.A.

    1987-01-01

    Unidirectional 45 Ca fluxes were measured in the turtle bladder under open-circuit and short-circuit conditions. In the open-circuited state net calcium flux (J net Ca ) was secretory (serosa to mucosa). Ouabain reversed J net Ca to an absorptive flux. Amiloride reduced both fluxes such that J net Ca was not significantly different from zero. Removal of mucosal sodium caused net calcium absorption; removal of serosal sodium caused calcium secretion. When bladders were short circuited, J net Ca decreased to approximately one-third of control value but remained secretory. When ouabain was added under short-circuit conditions, J net Ca was similar in magnitude and direction to ouabain under open-circuited conditions (i.e., absorptive). Tissue 45 Ca content was ≅30-fold lower when the isotope was placed in the mucosal bath, suggesting that the apical membrane is the resistance barrier to calcium transport. The results obtained in this study are best explained by postulating a Ca 2+ -ATPase on the serosa of the turtle bladder epithelium and a sodium-calcium antiporter on the mucosa. In this model, the energy for calcium movement would be supplied, in large part, by the Na + -K + -ATPase. By increasing cell sodium, ouabain would decrease the activity of the mucosal sodium-calcium exchanger (or reverse it), uncovering active calcium transport across the serosa

  9. Calcium chromate process related investigations

    International Nuclear Information System (INIS)

    Dillard, B.M.

    1979-01-01

    A pilot plant for production of calcium chromate has been scaled up to a small production facility at the General Electric Neutron Devices Department. In preparation for this scale-up, the process and final product were studied in order to evaluate problems not considered previously. The variables and processes studied included: (1) the determination of optimum drying temperature and time for product analysis; (2) the effect of the grade of lime used as the precipitating agent on the purity of the calcium chromate; (3) product purity when calcium chromate is precipitated by the addition of ammonium chromate to slaked lime; (4) the reagents best suited for cleaning calcium chromate spills; and (5) methods for determining hydroxide ion concentration in calcium chromate. The optimum drying time for the product before analysis is four hours at 600 0 C. Gases evolved at various temperatures during the drying process were carbon dioxide and water vapor. Technical grade lime produced calcium chromate of the highest purity. Both nitric and acetic acids were efficient dissolvers of calcium chromate spills. Direct titration of hydroxide ion with sulfuric acid gave an average recovery of 93% for samples spiked with calcium hydroxide. 1 figure, 17 tables

  10. Calcium addition in straw gasification

    DEFF Research Database (Denmark)

    Risnes, H.; Fjellerup, Jan Søren; Henriksen, Ulrik Birk

    2003-01-01

    The present work focuses on the influence of calcium addition in gasification. The inorganic¿organic element interaction as well as the detailed inorganic¿inorganic elements interaction has been studied. The effect of calcium addition as calcium sugar/molasses solutions to straw significantly...... affected the ash chemistry and the ash sintering tendency but much less the char reactivity. Thermo balance test are made and high-temperature X-ray diffraction measurements are performed, the experimental results indicate that with calcium addition major inorganic¿inorganic reactions take place very late...... in the char conversion process. Comprehensive global equilibrium calculations predicted important characteristics of the inorganic ash residue. Equilibrium calculations predict the formation of liquid salt if sufficient amounts of Ca are added and according to experiments as well as calculations calcium binds...

  11. Ammonia Oxidation and Nitrite Reduction in the Verrucomicrobial Methanotroph Methylacidiphilum fumariolicum SolV

    Directory of Open Access Journals (Sweden)

    Sepehr S. Mohammadi

    2017-09-01

    Full Text Available The Solfatara volcano near Naples (Italy, the origin of the recently discovered verrucomicrobial methanotroph Methylacidiphilum fumariolicum SolV was shown to contain ammonium (NH4+ at concentrations ranging from 1 to 28 mM. Ammonia (NH3 can be converted to toxic hydroxylamine (NH2OH by the particulate methane monooxygenase (pMMO, the first enzyme of the methane (CH4 oxidation pathway. Methanotrophs rapidly detoxify the intermediate NH2OH. Here, we show that strain SolV performs ammonium oxidation to nitrite at a rate of 48.2 nmol NO2-.h−1.mg DW−1 under O2 limitation in a continuous culture grown on hydrogen (H2 as an electron donor. In addition, strain SolV carries out nitrite reduction at a rate of 74.4 nmol NO2-.h−1.mg DW−1 under anoxic condition at pH 5–6. This range of pH was selected to minimize the chemical conversion of nitrite (NO2- potentially occurring at more acidic pH values. Furthermore, at pH 6, we showed that the affinity constants (Ks of the cells for NH3 vary from 5 to 270 μM in the batch incubations with 0.5–8% (v/v CH4, respectively. Detailed kinetic analysis showed competitive substrate inhibition between CH4 and NH3. Using transcriptome analysis, we showed up-regulation of the gene encoding hydroxylamine dehydrogenase (haoA cells grown on H2/NH4+ compared to the cells grown on CH4/NO3- which do not have to cope with reactive N-compounds. The denitrifying genes nirk and norC showed high expression in H2/NH4+ and CH4/NO3- grown cells compared to cells growing at μmax (with no limitation while the norB gene showed downregulation in CH4/NO3- grown cells. These cells showed a strong upregulation of the genes in nitrate/nitrite assimilation. Our results demonstrate that strain SolV can perform ammonium oxidation producing nitrite. At high concentrations of ammonium this may results in toxic effects. However, at low oxygen concentrations strain SolV is able to reduce nitrite to N2O to cope with this toxicity.

  12. Evolution of the Calcium Paradigm: The Relation between Vitamin D, Serum Calcium and Calcium Absorption

    Directory of Open Access Journals (Sweden)

    Borje E. Christopher Nordin

    2010-09-01

    Full Text Available Osteoporosis is the index disease for calcium deficiency, just as rickets/osteomalacia is the index disease for vitamin D deficiency, but there is considerable overlap between them. The common explanation for this overlap is that hypovitaminosis D causes malabsorption of calcium which then causes secondary hyperparathyroidism and is effectively the same thing as calcium deficiency. This paradigm is incorrect. Hypovitaminosis D causes secondary hyperparathyroidism at serum calcidiol levels lower than 60 nmol/L long before it causes malabsorption of calcium because serum calcitriol (which controls calcium absorption is maintained until serum calcidiol falls below 20 nmol/L. This secondary hyperparathyroidism, probably due to loss of a “calcaemic” action of vitamin D on bone first described in 1957, destroys bone and explains why vitamin D insufficiency is a risk factor for osteoporosis. Vitamin D thus plays a central role in the maintenance of the serum (ionised calcium, which is more important to the organism than the preservation of the skeleton. Bone is sacrificed when absorbed dietary calcium does not match excretion through the skin, kidneys and bowel which is why calcium deficiency causes osteoporosis in experimental animals and, by implication, in humans.

  13. Dog rose (Rosa canina L.) as a functional ingredient in porcine frankfurters without added sodium ascorbate and sodium nitrite.

    Science.gov (United States)

    Vossen, Els; Utrera, Mariana; De Smet, Stefaan; Morcuende, David; Estévez, Mario

    2012-12-01

    The effect of dog rose (Rosa canina L.; RC), rich in polyphenols and ascorbic acid, on lipid and protein oxidation, colour stability and texture of frankfurters was investigated. Four treatments were prepared: with 5 or 30 g/kg RC extract and without sodium ascorbate and sodium nitrite (5RC and 30RC, respectively), a positive control (with sodium ascorbate and sodium nitrite; PC) and a negative control (without sodium ascorbate, sodium nitrite or RC extract; NC). Hexanal values were much higher throughout storage in NC compared to RC and PC frankfurters (Prose can act as a natural antioxidant in frankfurters, but not as full replacer for sodium nitrite. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Dissimilatory reduction of nitrate and nitrite in the bovine rumen: nitrous oxide production and effect of acetylene.

    Science.gov (United States)

    Kaspar, H F; Tiedje, J M

    1981-03-01

    15N tracer methods and gas chromatography coupled to an electron capture detector were used to investigate dissimilatory reduction of nitrate and nitrite by the rumen microbiota of a fistulated cow. Ammonium was the only 15N-labeled end product of quantitative significance. Only traces of nitrous oxide were detected as a product of nitrate reduction; but in experiments with nitrite, up to 0.3% of the added nitrogen accumulated as nitrous oxide, but it was not further reduced. Furthermore, when 13NO3- was incubated with rumen microbiota virtually no [13N]N2 was produced. Acetylene partially inhibited the reduction of nitrite to ammonium as well as the formation of nitrous oxide. It is suggested that in the rumen ecosystem nitrous oxide is a byproduct of dissimilatory nitrite reduction to ammonium rather than a product of denitrification and that the latter process is absent from the rumen habitat.

  15. Nitrite sensing composite systems based on a core-shell emissive-superamagnetic structure: Construction, characterization and sensing behavior

    Science.gov (United States)

    Yang, Yan; Liu, Liang; Zha, Jianhua; Yuan, Ningyi

    2017-04-01

    Two recyclable nitrite sensing composite samples were designed and constructed through a core-shell structure, with Fe3O4 nanoparticles as core, silica molecular sieve MCM-41 as shell and two rhodamine derivatives as chemosensors, respectively. These samples and their structure were identified with their electron microscopy images, N2 adsorption/desorption isotherms, magnetic response, IR spectra and thermogravimetric analysis. Their nitrite sensing behavior was discussed based on emission intensity quenching, their limit of detection was found as low as 1.2 μM. Further analysis suggested a static sensing mechanism between nitrite and chemosensors through an additive reaction between NO+ and chemosensors. After finishing their nitrite sensing, these composite samples and their emission could be recycled and recovered by sulphamic acid.

  16. Outcompeting nitrite-oxidizing bacteria in single-stage nitrogen removal in sewage treatment plants: a model-based study.

    Science.gov (United States)

    Pérez, Julio; Lotti, Tommaso; Kleerebezem, Robbert; Picioreanu, Cristian; van Loosdrecht, Mark C M

    2014-12-01

    This model-based study investigated the mechanisms and operational window for efficient repression of nitrite oxidizing bacteria (NOB) in an autotrophic nitrogen removal process. The operation of a continuous single-stage granular sludge process was simulated for nitrogen removal from pretreated sewage at 10 °C. The effects of the residual ammonium concentration were explicitly analyzed with the model. Competition for oxygen between ammonia-oxidizing bacteria (AOB) and NOB was found to be essential for NOB repression even when the suppression of nitrite oxidation is assisted by nitrite reduction by anammox (AMX). The nitrite half-saturation coefficient of NOB and AMX proved non-sensitive for the model output. The maximum specific growth rate of AMX bacteria proved a sensitive process parameter, because higher rates would provide a competitive advantage for AMX. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Interspecific variation and plasticity in hemoglobin nitrite reductase activity and its correlation with oxygen affinity in vertebrates

    DEFF Research Database (Denmark)

    Jensen, Frank B.; Kolind, Rasmus A. H.; Jensen, Natashia S.

    2017-01-01

    -dependent manner. The initial second order rate constant of the deoxyHb-mediated nitrite reduction showed a strong curvilinear correlation with oxygen affinity among all ectothermic vertebrates, and the relationship also applied to plastic variations of Hb properties via organic phosphates. The relationship...... determines oxygen affinity. In the present study we investigated nitrite reductase activity and O2 affinity in Hbs from ten different vertebrate species under identical conditions to disclose interspecific variations and allow an extended test for a correlation between the rate constant for nitrite reduction...... and O2 affinity. We also tested plastic changes in Hb properties via addition of T-structure-stabilizing organic phosphates (ATP and GTP). The decay in deoxyHb during its reaction with nitrite was exponential-like in ectotherms (Atlantic hagfish, carp, crucian carp, brown trout, rainbow trout, cane toad...

  18. Diversity of nitrite reductase genes (nirS) in the denitrifying water column of the coastal Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Jayakumar, D.A.; Francis, C.A.; Naqvi, S.W.A.; Ward, B.B.

    Denitrification often occurs in the water column, underlying zones of intense productivity and decomposition in upwelling regions. In the denitrifying zone off the southwest coast of India, high concentrations of nitrite (greater than 15 mu M...

  19. Intermittent Aeration Suppresses Nitrite-Oxidizing Bacteria in Membrane-Aerated Biofilms: A Model-Based Explanation

    DEFF Research Database (Denmark)

    Ma, Yunjie; Domingo Felez, Carlos; Plósz, Benedek G.

    2017-01-01

    . On the basis of dissolved oxygen (DO), ammonium, nitrite, and nitrate profiles within the biofilm and in the bulk, a 1-dimensional nitrifying biofilm model was developed and calibrated. The model was utilized to explore the potential mechanisms of NOB suppression associated with intermittent aeration...... nitritation, strategies to suppress nitrite-oxidizing bacteria (NOB) are needed, which are ideally grounded on an understanding of underlying mechanisms. In this study, a nitrifying MABR was operated under intermittent aeration. During eight months of operation, AOB dominated, while NOB were suppressed...... during intermittent aeration was mostly explained by periodic inhibition caused by free ammonia due to periodic transient pH upshifts. Dissolved oxygen limitation did not govern NOB suppression. Different intermittent aeration strategies were then evaluated for nitritation success in intermittently...

  20. Colour formation in fermented sausages by meat-associated staphylococci with different nitrite- and nitrate-reductase activities

    DEFF Research Database (Denmark)

    Gøtterup, Jacob; Olsen, Karsten; Knøchel, Susanne

    2008-01-01

    nitrate depended on the specific Staphylococcus strain. Strains with high nitrate-reductase activity showed a significantly faster rate of pigment formation, but other factors were of influence as well. Product stability for the sliced, packaged sausage was evaluated as surface colour and oxidation......Three Staphylococcus strains, S. carnosus, S. simulans and S. saprophyticus, selected due to their varying nitrite and/or nitrate-reductase activities, were used to initiate colour formation during sausage fermentation. During fermentation of sausages with either nitrite or nitrate added, colour...... with hexanal content, and may be used as predictive tools. Overall, nitrite- and nitrate-reductase activities of Staphylococcus strains in nitrite-cured sausages were of limited importance regarding colour development, while in nitrate-cured sausages strains with higher nitrate reductase activity were crucial...

  1. Nitric oxide formation from the reaction of nitrite with carp and rabbit hemoglobin at intermediate oxygen saturations

    DEFF Research Database (Denmark)

    Jensen, Frank Bo

    2008-01-01

    The nitrite reductase activity of deoxyhemoglobin has received much recent interest because the nitric oxide produced in this reaction may participate in blood flow regulation during hypoxia. The present study used spectral deconvolution to characterize the reaction of nitrite with carp and rabbit...... hemoglobin at different constant oxygen tensions that generate the full range of physiological relevant oxygen saturations. Carp is a hypoxia-tolerant species with very high hemoglobin oxygen affinity, and the high R-state character and low redox potential of the hemoglobin is hypothesized to promote...... NO generation from nitrite. The reaction of nitrite with deoxyhemoglobin leads to a 1 : 1 formation of nitrosylhemoglobin and methemoglobin in both species. At intermediate oxygen saturations, the reaction with deoxyhemoglobin is clearly favored over that with oxyhemoglobin, and the oxyhemoglobin reaction...

  2. Combined effects of gamma radiation doses and sodium nitrite content on the lipid oxidation and color of mortadella.

    Science.gov (United States)

    Dutra, Monalisa Pereira; Cardoso, Giselle Pereira; Fontes, Paulo Rogério; Silva, Douglas Roberto Guimarães; Pereira, Marcio Tadeu; Ramos, Alcinéia de Lemos Souza; Ramos, Eduardo Mendes

    2017-12-15

    The effects of different doses of gamma radiation (0-20kGy) on the color and lipid oxidation of mortadella prepared with increasing nitrite levels (0-300ppm) were evaluated using a central composite rotatable design. Higher radiation doses increased the redox potential, promoted the lipid oxidation and elevating the hue color of the mortadellas. Nevertheless, higher addition of sodium nitrite elevated the residual nitrite content, reduced the lipid oxidation and promoted the increase of redness and the reduce of hue color of the mortadellas, regardless of the radiation dose applied. Nitrite addition had a greater effect than irradiation on the quality parameters evaluated, and even at low levels (∼75ppm), its use decreased the deleterious effects of irradiation at doses as high as 20kGy. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Effect of potential Hanford ferrocyanide waste constituents on the reaction between ferrocyanide and nitrates/nitrites

    International Nuclear Information System (INIS)

    Scheele, R.D.; Burger, L.L.; Sell, R.L.

    1993-02-01

    During the 1950s, ferrocyanide- and nitrate-bearing wastes were produced at Hanford. A concern about continued safe storage and future treatment of these wastes has arisen because ferrocyanide and nitrate mixtures can explode when heated. Because of this concern, the Pacific Northwest Laboratory has performed experimental studies to determine the conditions needed to continue storing the wastes safely. In this paper, we present the results of our studies on the effects of other potential ferrocyanide waste constituents on the explosivity of mixtures of sodium nickel ferrocyanide and sodium nitrate and nitrite. In particular, this paper presents the results of investigations on the diluent effects of equimolar sodium nitrate and nitrite, sodium nickel ferrocyanide, and sodium aluminate, and the catalyst or initiator effects of nickel sulfide

  4. Electrochemical preparation of iron cuboid nanoparticles and their catalytic properties for nitrite reduction

    International Nuclear Information System (INIS)

    Chen Yanxin; Chen Shengpei; Chen Qingsong; Zhou Zhiyou; Sun Shigang

    2008-01-01

    Iron cuboid nanoparticles supported on glassy carbon (denoted nm-Fe/GC) were prepared by electrochemical deposition under cyclic voltammetric (CV) conditions. The structure and composition of the Fe nanomaterials were characterized by scanning electron microscopy (SEM), selected area electron diffraction (SAED), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX). The results demonstrated that the Fe cuboid nanoparticles are dispersed discretely on GC substrate with an average size ca. 171 nm, and confirmed that the electrochemical synthesized nanocubes are single crystals of pure Fe. The catalytic properties of the Fe cuboid nanoparticles towards nitrite electroreduction were investigated, and enhanced electrocatalytic activity of the Fe nanocubes has been determined. In comparison with the data obtained on a bulk-Fe electrode, the onset potential of nitrite reduction on nm-Fe/GC is positively sifted by 100 mV, and the steady reduction current density is enhanced about 2.4-3.2 times

  5. Microbial resource management for the mitigation of nitrous oxide emissions from the Partial Nitritation- Anammox process

    DEFF Research Database (Denmark)

    Blum, Jan-Michael

    Urban wastewater treatment plants are designed to remove pathogens and pollutants from wastewater in order to provide sanitation and to protect receiving water bodies from eutrophication. Reactive nitrogen, mainly in the form of ammonium, is one of the components in wastewater that is converted...... to dinitrogen gas during treatment. The Partial Nitritation-Anammox process (PNA) uses the capacity of autotrophic aerobic and anaerobic ammonia oxidizing bacteria (AOB and AnAOB) to perform this task. The process is mainly applied to treat ammonium-rich wastewater streams with low concentrations of organic...... with the specific ammonia removal rate, while during non-aerated phases net N2O production rates were positively correlated with the nitrite concentration (NO2-). Operation of PNA at reduced specific ammonia removal rates is, therefore, a feasible strategy to mitigate N2O emissions. However, when high ammonium...

  6. Preparing electrochemical active hierarchically porous carbons for detecting nitrite in drinkable water

    KAUST Repository

    Ding, Baojun

    2016-01-13

    A class of hierarchically porous carbons were prepared by a facile dual-templating approach. The obtained samples were characterized by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, Brunaner-Emmett-Teller measurement and electrochemical work station, respectively. The porous carbons could possess large specific surface area, interconnected pore structures, high conductivity and graphitizing degree. The resulting materials were used to prepare integrated modified electrodes. Based on the experimental results, the as-prepared hierarchically porous graphite (HPG) modified electrode showed the best electroactive performances toward the detection of nitrite with a detection limit of 8.1 × 10-3 mM. This HPG electrode was also repeatable and stable for 6 weeks. Moreover, this electrode was used for the determination of nitrite in drinkable water, and had acceptable recoveries. © The Royal Society of Chemistry 2016.

  7. Sustained release of growth hormone and sodium nitrite from biomimetic collagen coating immobilized on silicone tubes improves endothelialization.

    Science.gov (United States)

    Salehi-Nik, Nasim; Malaie-Balasi, Zahra; Amoabediny, Ghassem; Banikarimi, Seyedeh Parnian; Zandieh-Doulabi, Behrouz; Klein-Nulend, Jenneke

    2017-08-01

    Biocompatibility of biomedical devices can be improved by endothelialization of blood-contacting parts mimicking the vascular endothelium's function. Improved endothelialization might be obtained by using biomimetic coatings that allow local sustained release of biologically active molecules, e.g. anti-thrombotic and growth-inducing agents, from nanoliposomes. We aimed to test whether incorporation of growth-inducing nanoliposomal growth hormone (nGH) and anti-thrombotic nanoliposomal sodium nitrite (nNitrite) into collagen coating of silicone tubes enhances endothelialization by stimulating endothelial cell proliferation and inhibiting platelet adhesion. Collagen coating stably immobilized on acrylic acid-grafted silicone tubes decreased the water contact angle from 102° to 56°. Incorporation of 50 or 500nmol/ml nNitrite and 100 or 1000ng/ml nGH into collagen coating decreased the water contact angle further to 48°. After 120h incubation, 58% nitrite and 22% GH of the initial amount of sodium nitrite and GH in nanoliposomes were gradually released from the nNitrite-nGH-collagen coating. Endothelial cell number was increased after surface coating of silicone tubes with collagen by 1.6-fold, and with nNitrite-nGH-collagen conjugate by 1.8-3.9-fold after 2days. After 6days, endothelial cell confluency in the absence of surface coating was 22%, with collagen coating 74%, and with nNitrite-nGH-collagen conjugate coating 83-119%. In the absence of endothelial cells, platelet adhesion was stimulated after collagen coating by 1.3-fold, but inhibited after nNitrite-nGH-collagen conjugate coating by 1.6-3.7-fold. The release of anti-thrombotic prostaglandin I 2 from endothelial cells was stimulated after nNitrite-nGH-collagen conjugate coating by 1.7-2.2-fold compared with collagen coating. Our data shows improved endothelialization and blood compatibility using nNitrite-nGH-collagen conjugate coating on silicone tubes suggesting that these coatings are highly suitable

  8. Supporting palladium metal on gold nanoparticles improves its catalysis for nitrite reduction.

    Science.gov (United States)

    Qian, Huifeng; Zhao, Zhun; Velazquez, Juan C; Pretzer, Lori A; Heck, Kimberly N; Wong, Michael S

    2014-01-07

    Nitrate (NO3(-)) and nitrite (NO2(-)) anions are often found in groundwater and surface water as contaminants globally, especially in agricultural areas due to nitrate-rich fertilizer use. One popular approach to studying the removal of nitrite/nitrate from water has been their degradation to dinitrogen via Pd-based reduction catalysis. However, little progress has been made towards understanding how the catalyst structure can improve activity. Focusing on the catalytic reduction of nitrite in this study, we report that Au NPs supporting Pd metal ("Pd-on-Au NPs") show catalytic activity that varies with volcano-shape dependence on Pd surface coverage. At room temperature, in CO2-buffered water, and under H2 headspace, the NPs were maximally active at a Pd surface coverage of 80%, with a first-order rate constant (k(cat) = 576 L g(Pd)(-1) min(-1)) that was 15x and 7.5x higher than monometallic Pd NPs (~4 nm; 40 L g(Pd)(-1) min(-1)) and Pd/Al2O3 (1 wt% Pd; 76 L g(Pd)(-1) min(-1)), respectively. Accounting only for surface Pd atoms, these NPs (576 L g(surface-Pd)(-1) min(-1)) were 3.6x and 1.6x higher than monometallic Pd NPs (160 L g(surface-Pd)(-1) min(-1)) and Pd/Al2O3 (361 L g(surface-Pd)(-1) min(-1)). These NPs retained ~98% of catalytic activity at a chloride concentration of 1 mM, whereas Pd/Al2O3 lost ~50%. The Pd-on-Au nanostructure is a promising approach to improve the catalytic reduction process for nitrite and, with further development, also for nitrate anions.

  9. Electroencephalographic Response to Sodium Nitrite May Predict Delayed Cerebral Ischemia After Severe Subarachnoid Hemorrhage.

    Science.gov (United States)

    Garry, Payashi S; Rowland, Matthew J; Ezra, Martyn; Herigstad, Mari; Hayen, Anja; Sleigh, Jamie W; Westbrook, Jon; Warnaby, Catherine E; Pattinson, Kyle T S

    2016-11-01

    Aneurysmal subarachnoid hemorrhage often leads to death and poor clinical outcome. Injury occurring during the first 72 hours is termed "early brain injury," with disruption of the nitric oxide pathway playing an important pathophysiologic role in its development. Quantitative electroencephalographic variables, such as α/δ frequency ratio, are surrogate markers of cerebral ischemia. This study assessed the quantitative electroencephalographic response to a cerebral nitric oxide donor (intravenous sodium nitrite) to explore whether this correlates with the eventual development of delayed cerebral ischemia. Unblinded pilot study testing response to drug intervention. Neuroscience ICU, John Radcliffe Hospital, Oxford, United Kingdom. Fourteen World Federation of Neurosurgeons grades 3, 4, and 5 patients (mean age, 52.8 yr [range, 41-69 yr]; 11 women). IV sodium nitrite (10 μg/kg/min) for 1 hour. Continuous electroencephalographic recording for 2 hours. The alpha/delta frequency ratio was measured before and during IV sodium nitrite infusion. Seven of 14 patients developed delayed cerebral ischemia. There was a +30% to +118% (range) increase in the alpha/delta frequency ratio in patients who did not develop delayed cerebral ischemia (p frequency ratio in those patients who did develop delayed cerebral ischemia (range, +11% to -31%) (p = 0.006, multivariate analysis accounting for major confounds). Administration of sodium nitrite after severe subarachnoid hemorrhage differentially influences quantitative electroencephalographic variables depending on the patient's susceptibility to development of delayed cerebral ischemia. With further validation in a larger sample size, this response may be developed as a tool for risk stratification after aneurysmal subarachnoid hemorrhage.

  10. Ultraviolet irradiation effects incorporation of nitrate and nitrite nitrogen into aquatic natural organic matter

    Science.gov (United States)

    Thorn, Kevin A.; Cox, Larry G.

    2012-01-01

    One of the concerns regarding the safety and efficacy of ultraviolet radiation for treatment of drinking water and wastewater is the fate of nitrate, particularly its photolysis to nitrite. In this study, 15N NMR was used to establish for the first time that UV irradiation effects the incorporation of nitrate and nitrite nitrogen into aquatic natural organic matter (NOM). Irradiation of 15N-labeled nitrate in aqueous solution with an unfiltered medium pressure mercury lamp resulted in the incorporation of nitrogen into Suwannee River NOM (SRNOM) via nitrosation and other reactions over a range of pH from approximately 3.2 to 8.0, both in the presence and absence of bicarbonate, confirming photonitrosation of the NOM. The major forms of the incorporated label include nitrosophenol, oxime/nitro, pyridine, nitrile, and amide nitrogens. Natural organic matter also catalyzed the reduction of nitrate to ammonia on irradiation. The nitrosophenol and oxime/nitro nitrogens were found to be susceptible to photodegradation on further irradiation when nitrate was removed from the system. At pH 7.5, unfiltered irradiation resulted in the incorporation of 15N-labeled nitrite into SRNOM in the form of amide, nitrile, and pyridine nitrogen. In the presence of bicarbonate at pH 7.4, Pyrex filtered (cutoff below 290–300 nm) irradiation also effected incorporation of nitrite into SRNOM as amide nitrogen. We speculate that nitrosation of NOM from the UV irradiation of nitrate also leads to production of nitrogen gas and nitrous oxide, a process that may be termed photo-chemodenitrification. Irradiation of SRNOM alone resulted in transformation or loss of naturally abundant heterocyclic nitrogens.

  11. Dietary Nitrates, Nitrites, and Nitrosamines Intake and the Risk of Gastric Cancer: A Meta-Analysis

    Science.gov (United States)

    Song, Peng; Wu, Lei; Guan, Wenxian

    2015-01-01

    The potential associations between dietary consumption of nitrates, nitrites, and nitrosamines and gastric cancer risk have been investigated by several studies, but yielded inconclusive results. We conducted a meta-analysis to provide a quantitative assessment of their relationships. Relevant articles were identified by a systematic literature searching of PubMed and Embase databases prior to August 2015. Random-effects models were employed to pool the relative risks. A total of 22 articles consisting of 49 studies—19 studies for nitrates, 19 studies for nitrites, and 11 studies for N-nitrosodimethylamine (NDMA)—were included. The summary relative risk of stomach cancer for the highest categories, compared with the lowest, was 0.80 (95% confidence interval (CI), 0.69–0.93) for dietary nitrates intake, 1.31 (95% CI, 1.13–1.52) for nitrites, and 1.34 (95% CI, 1.02–1.76) for NDMA (p for heterogeneity was 0.015, 0.013 and NDMA could not be eliminated completely through stratified analysis. Although significant associations were all observed in case-control studies, the cohort studies still showed a slight trend. The dose-response analysis indicated similar results as well. High nitrates intake was associated with a weak but statistically significant reduced risk of gastric cancer. Whereas increased consumption of nitrites and NDMA seemed to be risk factors for cancer. Due to the lack of uniformity for exposure assessment across studies, further prospective researches are warranted to verify these findings. PMID:26633477

  12. Construction of effective disposable biosensors for point of care testing of nitrite.

    Science.gov (United States)

    Monteiro, Tiago; Rodrigues, Patrícia R; Gonçalves, Ana Luisa; Moura, José J G; Jubete, Elena; Añorga, Larraitz; Piknova, Barbora; Schechter, Alan N; Silveira, Célia M; Almeida, M Gabriela

    2015-09-01

    In this paper we aim to demonstrate, as a proof-of-concept, the feasibility of the mass production of effective point of care tests for nitrite quantification in environmental, food and clinical samples. Following our previous work on the development of third generation electrochemical biosensors based on the ammonia forming nitrite reductase (ccNiR), herein we reduced the size of the electrodes' system to a miniaturized format, solved the problem of oxygen interference and performed simple quantification assays in real samples. In particular, carbon paste screen printed electrodes (SPE) were coated with a ccNiR/carbon ink composite homogenized in organic solvents and cured at low temperatures. The biocompatibility of these chemical and thermal treatments was evaluated by cyclic voltammetry showing that the catalytic performance was higher with the combination acetone and a 40°C curing temperature. The successful incorporation of the protein in the carbon ink/solvent composite, while remaining catalytically competent, attests for ccNiR's robustness and suitability for application in screen printed based biosensors. Because the direct electrochemical reduction of molecular oxygen occurs when electroanalytical measurements are performed at the negative potentials required to activate ccNiR (ca.-0.4V vs Ag/AgCl), an oxygen scavenging system based on the coupling of glucose oxidase and catalase activities was successfully used. This enabled the quantification of nitrite in different samples (milk, water, plasma and urine) in a straightforward way and with small error (1-6%). The sensitivity of the biosensor towards nitrite reduction under optimized conditions was 0.55 A M(-1) cm(-2) with a linear response range 0.7-370 μM. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Dietary nitrate and nitrite intake and risk of colorectal cancer in the Shanghai Women's Health Study.

    Science.gov (United States)

    Dellavalle, Curt T; Xiao, Qian; Yang, Gong; Shu, Xiao-Ou; Aschebrook-Kilfoy, Briseis; Zheng, Wei; Lan Li, Hong; Ji, Bu-Tian; Rothman, Nathaniel; Chow, Wong-Ho; Gao, Yu-Tang; Ward, Mary H

    2014-06-15

    Nitrate and nitrite are precursors of endogenously formed N-nitroso compounds (NOC), known animal carcinogens. Nitrosation reactions forming NOCs can be inhibited by vitamin C and other antioxidants. We prospectively investigated the association between dietary nitrate and nitrite intake and risk of colorectal cancer in the Shanghai Women's Health Study, a cohort of 73,118 women ages 40-70 residing in Shanghai. We evaluated effect modification by factors that affect endogenous formation of NOCs: vitamin C (at or above/below median) and red meat intake (at or above/below median). Nitrate, nitrite and other dietary intakes were estimated from a 77-item food frequency questionnaire administered at baseline. Over a mean of 11 years of follow-up, we identified 619 colorectal cancer cases (n = 383, colon; n = 236, rectum). Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox proportional hazard regression. Overall, nitrate intake was not associated with colorectal cancer risk (HR = 1.08; 95% CI: 0.73-1.59). However, among women with vitamin C intake below the median (83.9 mg day(-1) ) and hence higher potential exposure to NOCs, risk of colorectal cancer increased with increasing quintiles of nitrate intake (highest vs. lowest quintile HR = 2.45; 95% CI: 1.15-5.18; p trend = 0.02). There was no association among women with higher vitamin C intake. We found no association between nitrite intake and risk of colorectal cancer overall or by intake level of vitamin C. Our findings suggest that high dietary nitrate intake among subgroups expected to have higher exposure to endogenously formed NOCs increases risk of colorectal cancer. © 2013 UICC.

  14. Dietary Nitrates, Nitrites, and Nitrosamines Intake and the Risk of Gastric Cancer: A Meta-Analysis

    OpenAIRE

    Peng Song; Lei Wu; Wenxian Guan

    2015-01-01

    The potential associations between dietary consumption of nitrates, nitrites, and nitrosamines and gastric cancer risk have been investigated by several studies, but yielded inconclusive results. We conducted a meta-analysis to provide a quantitative assessment of their relationships. Relevant articles were identified by a systematic literature searching of PubMed and Embase databases prior to August 2015. Random-effects models were employed to pool the relative risks. A total of 22 articles ...

  15. Nitrate and nitrite ingestion and risk of ovarian cancer among postmenopausal women in Iowa.

    Science.gov (United States)

    Inoue-Choi, Maki; Jones, Rena R; Anderson, Kristin E; Cantor, Kenneth P; Cerhan, James R; Krasner, Stuart; Robien, Kim; Weyer, Peter J; Ward, Mary H

    2015-07-01

    Nitrate and nitrite are precursors in the endogenous formation of N-nitroso compounds (NOC), potential human carcinogens. We evaluated the association of nitrate and nitrite ingestion with postmenopausal ovarian cancer risk in the Iowa Women's Health Study. Among 28,555 postmenopausal women, we identified 315 incident epithelial ovarian cancers from 1986 to 2010. Dietary nitrate and nitrite intakes were assessed at baseline using food frequency questionnaire data. Drinking water source at home was obtained in a 1989 follow-up survey. Nitrate-nitrogen (NO3 -N) and total trihalomethane (TTHM) levels for Iowa public water utilities were linked to residences and average levels were computed based on each woman's duration at the residence. We computed multivariable-adjusted hazard ratios (HR) and 95% confidence intervals (CI) using Cox proportional hazards regression. We tested interactions of nitrate with TTHMs and dietary factors known to influence NOC formation. Ovarian cancer risk was 2.03 times higher (CI = 1.22-3.38, ptrend  = 0.003) in the highest quartile (≥2.98 mg/L) compared with the lowest quartile (≤0.47 mg/L; reference) of NO3 -N in public water, regardless of TTHM levels. Risk among private well users was also elevated (HR = 1.53, CI = 0.93-2.54) compared with the same reference group. Associations were stronger when vitamin C intake was nitrate was inversely associated with ovarian cancer risk (ptrend  = 0.02); whereas, dietary nitrite from processed meats was positively associated with the risk (ptrend  = 0.04). Our findings indicate that high nitrate levels in public drinking water and private well use may increase ovarian cancer risk among postmenopausal women. © 2014 UICC.

  16. DECREASING OF SODIUM NITRITE CONTENT IN COOKED SAUSAGES USING DENITRIFYING MICROORGANISMS

    Directory of Open Access Journals (Sweden)

    Bal-Prylypko L. V.

    2015-08-01

    Full Text Available The purpose of this work was to study reduction of sodium nitrite in cooked sausages by adding of the optimized amount of denitrifying microorganisms to the bacterial preparation maintaining quality characteristics of the product. To develop biotechnology of boiled sausages «Naturel» we selected bacterial preparation based on nitrite-reducing strains of Staphylococcus carnosus and S. carnosus ssp.utilis. It was used generally accepted and special methods. The content of total pigments and nitrozopigments was determined by a method based on the extraction of meat pigments by aqueous acetone; color stability of final products was evaluated as the difference in optical density of nitroso pigment extracts before and after exposure (40 min of the sample under the light source; analytical processing of the experimental data was carried out using modern software; quantitative evaluation of color characteristics was performed in the RGB using a multifunctional device Epson Stylus TX400. Mathematical modeling was carried out on the basis of full factorial experiment such as 22, the optimization was performed by Box–Wilson. According to the study, using of the bacterial preparation based on nitrite-reducing strains of Staphylococcus carnosus and S. carnosus ssp. utilis in biotechnology of boiled sausages «Naturel» has a positive effect on the formation of the complex of required color characteristics of final products (for prototypes of sausages the index redness was 1. 61 times higher compared to the control. Degradation of sodium nitrite and formation of nitroso pigments were intensified that improved the stability of color during the storage (the index of color fastness of experimental cooked sausages was higher by 19%. The results of performed investigations illustrate the possibility of production of cooked sausages with a minimized content of synthetic food additives and ingredients.

  17. Simultaneous determination of nitrite and nitrate in water by chemiluminescent flow-injection analysis

    Czech Academy of Sciences Publication Activity Database

    Mikuška, Pavel; Večeřa, Zbyněk

    2003-01-01

    Roč. 495, 1-2 (2003), s. 225-232 ISSN 0003-2670 R&D Projects: GA AV ČR IAA4031105; GA ČR GA526/03/1182 Grant - others:COPERNICUS(XE) SUB-AERO-EVK2-1999-0052 Institutional research plan: CEZ:AV0Z4031919 Keywords : nitrate * nitrite * FIA Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.210, year: 2003

  18. Biological responses of Neotropical freshwater fish Lophiosilurus alexandri exposed to ammonia and nitrite.

    Science.gov (United States)

    Dos Santos Silva, Márcio José; da Costa, Franklin Fernando Batista; Leme, Fabiola Paes; Takata, Rodrigo; Costa, Deliane Cristina; Mattioli, Cristiano Campos; Luz, Ronald Kennedy; Miranda-Filho, Kleber Campos

    2018-03-01

    This study aimed to elucidate the responses of the Neotropical fish Lophiosilurus alexandri exposed to ammonia and nitrite, following a period of recovering. Acute toxicity tests lasted 96h, subchronic toxicity tests lasted eight days and the detoxification trial lasted four days. Groups of 12 juveniles were maintained in 90-L tanks and treated with increasing concentrations of ammonia and nitrite, except during the recovery test. All treatments were performed with two replicates. The median lethal concentrations (LC 50 ) of 24, 48, 72 and 96h were estimated at 30.12; 24.35; 19.24 and 18.68mg·L -1 TA-N; 5.37; 4.57; 3.75 and 3.66mg·L -1 NH 3 -N and 20.37; 7.78; 7.09 and 5.86mg·L -1 NO 2 - -N, respectively. The NO 2 - caused significant decrease in hematocrit and increase in the urea levels during short-term exposure, with recovery of homeostasis after the subchronic and detox period. Acute exposure to ammonia increased the enzyme profile of transaminases, glucose and urea. Urea concentration remained high in the subchronic and detox tests. Histopathologies were observed in animals exposed to ammonia in both toxicity tests. It was highlighted detachment of epithelium, hyperemia and necrosis in the gills. Exposure to NO 2 - caused epithelium detachment and aneurysm. Vacuolization and swelling of hepatocytes were the most common injury for both nitrogenous compounds. We concluded that the L. alexandri has moderate tolerance to ammonia and nitrite. The recovery period revealed remedial response to ammonia and nitrite exposure. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Short-and long-term effects of ammonia and nitrite on the anammox process

    International Nuclear Information System (INIS)

    Fernandez, I.; Campos, J. L.; Mosquera-Corral, A.; Mendez, R.

    2009-01-01

    Auto trophic anaerobic ammonium oxidation (Anammox) process is a feasible alternative to treat industrial wastewater with high ammonia concentration but low content of organic matter. In this process ammonium and nitrite are used by Planctomycete-type bacteria under anoxic conditions to generate nitrogen gas. Both substrates can exert inhibitory effects on the process, causing the decrease of the specific activity of the biomass and the loss of the performance and stability of reactors. (Author)

  20. Mechanism of Pitting Corrosion Prevention by Nitrite in Carbon Steel Exposed to Dilute Salt Solutions

    International Nuclear Information System (INIS)

    Zapp, Philip E.; Zee, John W. van

    2002-01-01

    The research has developed a broad fundamental understanding of the inhibition action of nitrite ions in preventing nitrate pitting corrosion of carbon steel tanks containing high-level radioactive waste. This fundamental understanding can be applied to specific situations during waste removal for permanent disposition and waste tank closure to ensure that the tanks are maintained safely. The results of the research provide the insight necessary to develop solutions that prevent further degradation

  1. Dissimilatory reduction of nitrate and nitrite in the bovine rumen: nitrous oxide production and effect of acetylene.

    OpenAIRE

    Kaspar, H F; Tiedje, J M

    1981-01-01

    15N tracer methods and gas chromatography coupled to an electron capture detector were used to investigate dissimilatory reduction of nitrate and nitrite by the rumen microbiota of a fistulated cow. Ammonium was the only 15N-labeled end product of quantitative significance. Only traces of nitrous oxide were detected as a product of nitrate reduction; but in experiments with nitrite, up to 0.3% of the added nitrogen accumulated as nitrous oxide, but it was not further reduced. Furthermore, whe...

  2. Development of estimates of dietary nitrates, nitrites, and nitrosamines for use with the short willet food frequency questionnaire

    OpenAIRE

    Griesenbeck, John S; Steck, Michelle D; Huber, John C; Sharkey, Joseph R; Rene, Antonio A; Brender, Jean D

    2009-01-01

    Abstract Background Studies have suggested that nitrates, nitrites, and nitrosamines have an etiologic role in adverse pregnancy outcomes and chronic diseases such as cancer. Although an extensive body of literature exists on estimates of these compounds in foods, the extant data varies in quality, quantified estimates, and relevance. Methods We developed estimates of nitrates, nitrites, and nitrosamines for food items listed in the Short Willet Food Frequency Questionnaire (WFFQ) as adapted ...

  3. STUDY ON DECREASE OF NITRITE AND NITRATE USAGE IN PROCESSED MEAT WITH ADDITION OF NATURAL SALT AND CARBON MONOXIDE

    Directory of Open Access Journals (Sweden)

    R. Sakata

    2017-01-01

    Full Text Available This study was carried out to examine the reddening of meat products due to the addition of natural yellow salt (YS and carbon monoxide (CO. Following YS or NaCl addition at 2% to pork subsequent to nitrite (0~100 ppm treatment, color development due to this addition was analyzed optically. Heme pigment content in the meat was also determined spectrophotometrically. YS was found to bring about greater reddening than NaCl, indicating residual nitrite and nitrate content to be significantly higher in meat containing YS, through the amount of either was quite small. The nitrite itself in YS could never explain the color formation by the YS. Because the YS included not only nitrite but also nitrate, the effects of nitrate on the color stability of cooked cured pork were examined. Nitrate inhibited the nitrite decrement and discoloration in the cooked cured ham. The degradation rate of nitrite was clearly found to decrease with nitric acid content. Nitrate does not appear to serve as a donor of nitrite, but rather inhibits nitrite reduction in cooked meat products, with consequent prolongation of color stability. Nitrate, observed in many rock salt and also in this case, could enhance the color formation. CO treatment of pork caused the formation of carboxy myoglobin (COMb with consequent reddening of the meat. COMb was shown to be heat-stable and form stably at pH 5.0 to 8.0 and to be extractable with water, but was barely extractable at all with acetone. Nitric oxide was found to have greater affinity toward myoglobin (Mb than CO. Nitrosyl Mb was noted to be stable in all meat products examined. CO was seen to be capable of controlling the extent of lipid oxidation.

  4. Fine structure characterization of zero-valent iron nanoparticles for decontamination of nitrites and nitrates in wastewater and groundwater

    Directory of Open Access Journals (Sweden)

    Kuen-Song Lin et al

    2008-01-01

    Full Text Available The main objectives of the present study were to investigate the chemical reduction of nitrate or nitrite species by zero-valent iron nanoparticle (ZVIN in aqueous solution and related reaction kinetics or mechanisms using fine structure characterization. This work also exemplifies the utilization of field emission-scanning electron microscope (FE–SEM, transmission electron microscopy (TEM, and x-ray diffraction (XRD to reveal the speciation and possible reaction pathway in a very complex adsorption and redox reaction process. Experimentally, ZVIN of this study was prepared by sodium borohydride reduction method at room temperature and ambient pressure. The morphology of as-synthesized ZVIN shows that the nearly ball and ultrafine particles ranged of 20–50 nm were observed with FE–SEM or TEM analysis. The kinetic model of nitrites or nitrates reductive reaction by ZVIN is proposed as a pseudo first-order kinetic equation. The nitrite and nitrate removal efficiencies using ZVIN were found 65–83% and 51–68%, respectively, based on three different initial concentrations. Based on the XRD pattern analyses, it is found that the quantitative relationship between nitrite and Fe(III or Fe(II is similar to the one between nitrate and Fe(III in the ZVIN study. The possible reason is due to the faster nitrite reduction by ZVIN. In fact, the occurrence of the relative faster nitrite reductive reaction suggested that the passivation of the ZVIN have a significant contribution to iron corrosion. The extended x-ray absorption fine structure (EXAFS or x-ray absorption near edge structure (XANES spectra show that the nitrites or nitrates reduce to N2 or NH3 while oxidizing the ZVIN to Fe2O3 or Fe3O4 electrochemically. It is also very clear that decontamination of nitrate or nitrite species in groundwater via the in-situ remediation with a ZVIN permeable reactive barrier would be environmentally attractive.

  5. Calcium and Calcium Supplements: Achieving the Right Balance

    Science.gov (United States)

    ... may have on heart attack risk. A similar controversy surrounds calcium and prostate cancer. Some studies have ... your agreement to the Terms and Conditions and Privacy Policy linked below. Terms and Conditions Privacy Policy ...

  6. Structural basis for dynamic mechanism of nitrate/nitrite antiport by NarK

    Science.gov (United States)

    Fukuda, Masahiro; Takeda, Hironori; Kato, Hideaki E.; Doki, Shintaro; Ito, Koichi; Maturana, Andrés D.; Ishitani, Ryuichiro; Nureki, Osamu

    2015-05-01

    NarK belongs to the nitrate/nitrite porter (NNP) family in the major facilitator superfamily (MFS) and plays a central role in nitrate uptake across the membrane in diverse organisms, including archaea, bacteria, fungi and plants. Although previous studies provided insight into the overall structure and the substrate recognition of NarK, its molecular mechanism, including the driving force for nitrate transport, remained elusive. Here we demonstrate that NarK is a nitrate/nitrite antiporter, using an in vitro reconstituted system. Furthermore, we present the high-resolution crystal structures of NarK from Escherichia coli in the nitrate-bound occluded, nitrate-bound inward-open and apo inward-open states. The integrated structural, functional and computational analyses reveal the nitrate/nitrite antiport mechanism of NarK, in which substrate recognition is coupled to the transport cycle by the concomitant movement of the transmembrane helices and the key tyrosine and arginine residues in the substrate-binding site.

  7. Structure of octaheme cytochrome c nitrite reductase from Thioalkalivibrio nitratireducens in a complex with phosphate

    International Nuclear Information System (INIS)

    Trofimov, A. A.; Polyakov, K. M.; Boiko, K. M.; Filimonenkov, A. A.; Dorovatovskii, P. V.; Tikhonova, T. V.; Popov, V. O.; Koval'chuk, M. V.

    2010-01-01

    Octaheme cytochrome c nitrite reductase from Thioalkalivibrio nitratireducens (TvNiR) catalyzes the reduction of nitrite and hydroxylamine to ammonia. The structures of the free enzyme and of the enzyme in complexes with the substrate (nitrite ion) and the inhibitor (azide ion) have been solved previously. In this study we report the structures of the oxidized complex of TvNiR with phosphate and of this complex reduced by europium(II) chloride (1.8- and 2.0-A resolution, the R factors are 15.9 and 16.7%, respectively) and the structure of the enzyme in the complex with cyanide (1.76-A resolution, the R factor is 16.5%), which was prepared by soaking a crystal of the oxidized phosphate complex of TvNiR. In the active site of the enzyme, the phosphate ion binds to the iron ion of the catalytic heme and to the side chains of the catalytic residues Arg131, Tyr303, and His361. The cyanide ion is coordinated to the heme-iron ion and is hydrogen bonded to the residue His361. In the structure of reduced TvNiR, the phosphate ion is bound in the same manner as in the structure of oxidized TvNiR, and the nine c oordinated europium ion is located on the surface of one of the crystallographically independent monomers of the enzyme.

  8. Structure of octaheme cytochrome c nitrite reductase from Thioalkalivibrio nitratireducens in a complex with phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Trofimov, A. A.; Polyakov, K. M., E-mail: kostya@eimb.relarn.ru [Russian Academy of Sciences, Engelhardt Institute of Molecular Biology (Russian Federation); Boiko, K. M.; Filimonenkov, A. A. [Russian Academy of Sciences, Bach Institute of Biochemistry (Russian Federation); Dorovatovskii, P. V. [Kurchatov Center for Synchrotron Radiation and Nanotechnology (Russian Federation); Tikhonova, T. V.; Popov, V. O. [Russian Academy of Sciences, Bach Institute of Biochemistry (Russian Federation); Koval' chuk, M. V. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2010-01-15

    Octaheme cytochrome c nitrite reductase from Thioalkalivibrio nitratireducens (TvNiR) catalyzes the reduction of nitrite and hydroxylamine to ammonia. The structures of the free enzyme and of the enzyme in complexes with the substrate (nitrite ion) and the inhibitor (azide ion) have been solved previously. In this study we report the structures of the oxidized complex of TvNiR with phosphate and of this complex reduced by europium(II) chloride (1.8- and 2.0-A resolution, the R factors are 15.9 and 16.7%, respectively) and the structure of the enzyme in the complex with cyanide (1.76-A resolution, the R factor is 16.5%), which was prepared by soaking a crystal of the oxidized phosphate complex of TvNiR. In the active site of the enzyme, the phosphate ion binds to the iron ion of the catalytic heme and to the side chains of the catalytic residues Arg131, Tyr303, and His361. The cyanide ion is coordinated to the heme-iron ion and is hydrogen bonded to the residue His361. In the structure of reduced TvNiR, the phosphate ion is bound in the same manner as in the structure of oxidized TvNiR, and the nine{sub c}oordinated europium ion is located on the surface of one of the crystallographically independent monomers of the enzyme.

  9. Yield of Ozone, Nitrite Nitrogen and Hydrogen Peroxide Versus Discharge Parameter Using APPJ Under Water

    International Nuclear Information System (INIS)

    Chen Bingyan; Wen Wen; Zhu Changping; Wang Yuan; Gao Ying; Fei Juntao; He Xiang; Yin Cheng; Jiang Yongfeng; Chen Longwei

    2016-01-01

    Discharge plasma in and in contact with water can be accompanied with ultraviolet radiation and electron impact, thus can generate hydroxyl radicals, ozone, nitrite nitrogen and hydrogen peroxide. In this paper, a non-equilibrium plasma processing system was established by means of an atmospheric pressure plasma jet immersed in water. The hydroxyl intensities and discharge energy waveforms were tested. The results show that the positive and negative discharge energy peaks were asymmetric, where the positive discharge energy peak was greater than the negative one. Meanwhile, the yield of ozone and nitrite nitrogen was enhanced with the increase of both the treatment time and the discharge energy. Moreover, the pH value of treated water was reduced rapidly and maintained at a lower level. The residual concentration of hydrogen peroxide in APPJ treated water was kept at a low level. Additionally, both the efficiency energy ratio of the yield of ozone and nitrite nitrogen and that of the removal of p-nitrophenol increased as a function of discharge energy and discharge voltage. The experimental results were fully analyzed and the chemical reaction equations and the physical processes of discharges in water were given. (paper)

  10. Synthesis, characterization and reactivity of nitrite and nitrosyl derivates of phosphane complexes of tetraamminrethenium (II)

    International Nuclear Information System (INIS)

    Souza Santos, L. de.

    1988-01-01

    The substitution reaction: trans-[Ru(NH 3 ) 4 P(III) (H 2 O)] 2+ + NO - 2 K 1 K -1 trans-[Ru(NH 3 ) 4 P(III) (NO 2 ) + + H 2 O. The reaction product has been isolated as trans-[Ru(NH 3 ) 4 P(III) (NO 2 )] (PF 6 ) and characterized by using electronic and infrared spectroscopies and cyclic voltammetry, microanalysis and conductometry techniques. This nitrite complex can be converted into the nitrosyl complex in solution by adding H + , according to: trans-[Ru(NH 3 ) 4 P(III) (NO 2 )] + + 2H + →sup (K)1 trans-[Ru(NH 3 ) 4 P(III) (NO)] 3+ + H 2 O which can be converted back to the nitrite derivative by adding alkali: trans-[Ru(NH 3 ) 4 P(III) (NO)] 3+ + 2 OH - →sup (K)-1 trans-[Ru(NH 3 ) 4 P(III) (NO 2 )] + + H 2 O. The nitrosyl complexes have been synthesized by reaction of NO with trans-[Ru(NH 3 ) 4 P(III) ( 2 O)] 2+ or by reacting the nitrite derivative in acidic solutions, and characterized by eletronic and infrared spetroscopies, cyclic voltametry, microanalysis, eletron paramagnetic resonance (E.P.R.) and nuclear magnetic resonance (N.M.R.) techniques. E.P.R. and N.M.R. data suggest that these complexes are diamagnetic and better formulated as Ru(II)-NO + . (author) [pt

  11. Modeling of Nitrous Oxide Production from Nitritation Reactors Treating Real Anaerobic Digestion Liquor.

    Science.gov (United States)

    Wang, Qilin; Ni, Bing-Jie; Lemaire, Romain; Hao, Xiaodi; Yuan, Zhiguo

    2016-04-29

    In this work, a mathematical model including both ammonium oxidizing bacteria (AOB) and heterotrophic bacteria (HB) is constructed to predict N2O production from the nitritation systems receiving the real anaerobic digestion liquor. This is for the first time that N2O production from such systems was modeled considering both AOB and HB. The model was calibrated and validated using experimental data from both lab- and pilot-scale nitritation reactors. The model predictions matched the dynamic N2O, ammonium, nitrite and chemical oxygen demand data well, supporting the capability of the model. Modeling results indicated that HB are the dominant contributor to N2O production in the above systems with the dissolved oxygen (DO) concentration of 0.5-1.0 mg O2/L, accounting for approximately 75% of N2O production. The modeling results also suggested that the contribution of HB to N2O production decreased with the increasing DO concentrations, from 75% at DO = 0.5 mg O2/L to 25% at DO = 7.0 mg O2/L, with a corresponding increase of the AOB contribution (from 25% to 75%). Similar to HB, the total N2O production rate also decreased dramatically from 0.65 to 0.25 mg N/L/h when DO concentration increased from 0.5 to 7.0 mg O2/L.

  12. Effects of hemin and nitrite on intestinal tumorigenesis in the A/J Min/+ mouse model.

    Directory of Open Access Journals (Sweden)

    Marianne Sødring

    Full Text Available Red and processed meats are considered risk factors for colorectal cancer (CRC; however, the underlying mechanisms are still unclear. One cause for the potential link between CRC and meat is the heme iron in red meat. Two pathways by which heme and CRC promotion may be linked have been suggested: fat peroxidation and N-nitrosation. In the present work we have used the novel A/J Min/+ mouse model to test the effects of dietary hemin (a model of red meat, and hemin in combination with nitrite (a model of processed meat on intestinal tumorigenesis. Mice were fed a low Ca2+ and vitamin D semi-synthetic diet with added hemin and/or nitrite for 8 weeks post weaning, before termination followed by excision and examination of the intestinal tract. Our results indicate that dietary hemin decreased the number of colonic lesions in the A/J Min/+ mouse. However, our results also showed that the opposite occurred in the small intestine, where dietary hemin appeared to stimulate tumor growth. Furthermore, we find that nitrite, which did not have an effect in the colon, appeared to have a suppressive effect on tumor growth in the small intestine.

  13. Salivary surrogates of plasma nitrite and catecholamines during a 21-week training season in swimmers.

    Directory of Open Access Journals (Sweden)

    Miguel Mauricio Díaz Gómez

    Full Text Available The collection of samples of saliva is noninvasive and straightforward, which turns saliva into an ideal fluid for monitoring the adaptive response to training. Here, we investigated the response of the salivary proteins alpha-amylase (sAA, chromogranin A (sCgA, and the concentration of total protein (sTP as well as salivary nitrite (sNO2 in relation to plasma catecholamines and plasma nitrite (pNO2, respectively. The variation in these markers was compared to the intensity and load of training during a 21-week training season in 12 elite swimmers. Overall, the salivary proteins tracked the concentration of plasma adrenaline and were inversely correlated with the training outcomes. No correlations were observed between sNO2 and pNO2. However, sNO2 correlated positively with the intensity and load of training. We argue that the decrease in sympathetic activity is responsible for the decrease in the concentration of proteins throughout the training season. Furthermore, the increase in nitrite is likely to reflect changes in hemodynamics and regulation of vascular tone. The association of the salivary markers with the training outcomes underlines their potential as noninvasive markers of training status in professional athletes.

  14. Effect of tomato paste and nitrite level on processing and quality characteristics of frankfurters.

    Science.gov (United States)

    Deda, M S; Bloukas, J G; Fista, G A

    2007-07-01

    Fourteen treatments of frankfurters (18% fat) were produced with two levels of sodium nitrite, 0 and 150mg/kg (0.015%), and seven levels (0%,2%,6%,8%,12% and 16%) of tomato paste with 12% soluble solids The higher the tomato paste level the higher the preference of consumers for frankfurters based on their colour. Frankfurters with 16% tomato paste had a sour taste while those with 12% tomato paste were the most acceptable. In a 2nd experiment three treatments of frankfurters (18% fat) were produced with 0, 50 and 100mg/kg of sodium nitrite and 12% tomato paste and a fourth (control) with only 150mg/kg sodium nitrite. Treatments with 12% tomato paste had lower (pnitrite, and higher (pnitrite (50 and 100mg/kg) and 12% tomato paste had the highest (pnitrites added to frankfurters can be reduced from 150mg/kg to 100mg/kg in combination with 12% tomato paste without any negative effect on the quality of the product.

  15. Effects of Processing Temperature on Color Properties of Dry-Cured Hams Made without Nitrite

    Directory of Open Access Journals (Sweden)

    Giovanni Parolari

    2016-04-01

    Full Text Available Dry cured hams were investigated for their ability to develop red color even at low temperature (3–4 °C and in the absence of added nitrites; results were compared with those obtained from nitrite-free hams made at conventional warm maturing temperatures. Colorimetric parameters (L*, a*, b*, and hue and concentration of the main pigments Zn protoporphyrin IX (ZnPP and heme were measured at three stages of preparation (six, nine, and 12 months, showing that red color was successfully formed at low temperatures, though at a slower rate and less intensively than under warm conditions. Major differences in the pattern of color development were found with the two processing temperatures. While the typical features of an enzyme-dependent mechanism, with a progressive drop in enzyme activity paralleling the synthesis of Zn protoporphyrin IX, were observed at warm temperatures, the same did not occur in cold-made hams, where the enzyme activity was almost unchanged throughout the process. These results, along with data from a descriptive sensory analysis, are supportive of a non-enzymatic mechanism leading to ZnPP (hence the red color under cold conditions, with an estimated three-month delay compared with nitrite-free hams manufactured in a warm maturing regimen.

  16. Effects of Processing Temperature on Color Properties of Dry-Cured Hams Made without Nitrite.

    Science.gov (United States)

    Parolari, Giovanni; Aguzzoni, Agnese; Toscani, Tania

    2016-04-29

    Dry cured hams were investigated for their ability to develop red color even at low temperature (3-4 °C) and in the absence of added nitrites; results were compared with those obtained from nitrite-free hams made at conventional warm maturing temperatures. Colorimetric parameters (L*, a*, b*, and hue) and concentration of the main pigments Zn protoporphyrin IX (ZnPP) and heme were measured at three stages of preparation (six, nine, and 12 months), showing that red color was successfully formed at low temperatures, though at a slower rate and less intensively than under warm conditions. Major differences in the pattern of color development were found with the two processing temperatures. While the typical features of an enzyme-dependent mechanism, with a progressive drop in enzyme activity paralleling the synthesis of Zn protoporphyrin IX, were observed at warm temperatures, the same did not occur in cold-made hams, where the enzyme activity was almost unchanged throughout the process. These results, along with data from a descriptive sensory analysis, are supportive of a non-enzymatic mechanism leading to ZnPP (hence the red color) under cold conditions, with an estimated three-month delay compared with nitrite-free hams manufactured in a warm maturing regimen.

  17. Methaemoglobinaemia associated with the use of cocaine and volatile nitrites as recreational drugs: a review

    Science.gov (United States)

    Hunter, Laura; Gordge, Laura; Dargan, Paul I; Wood, David M

    2011-01-01

    Methaemoglobinaemia can cause significant tissue hypoxia, leading to severe, potentially life-threatening clinical features and/or death. Over recent years there have been increasing reports of methaemoglobinaemia related to recreational drug use. There have been 25 articles describing methaemoglobinaemia related to recreational use of volatile nitrites (poppers) and more recently, four reports of methaemoglobinaemia in association with recreational cocaine use. In this article we discuss the mechanisms by which methaemoglobinaemia occurs in relation to the use of both volatile nitrites and cocaine, and summarize the published cases of recreational drug-related methaemoglobinaemia. The volatile nitrites can cause methaemoglobinaemia directly through their activity as oxidizing agents. However, with cocaine, methaemoglobinaemia is related to adulterants such as local anaesthetics or phenacetin, rather than to the cocaine itself. Clinicians managing patients with acute recreational drug toxicity should be aware of the potential for methaemoglobinaemia in these patients, particularly in patients with cyanosis or unexplained low oxygen saturations on pulse oximetry, and ensure that appropriate and timely management is provided, including, where appropriate, the use of methylthioninium chloride (methylene blue). PMID:21352269

  18. Evaluation of Nitrate and Nitrite Reduction Kinetics Related to Liquid-Air-Interface Corrosion

    International Nuclear Information System (INIS)

    Li, Xiaoji; Gui, F.; Cong, Hongbo; Brossia, C.S.; Frankel, G.S.

    2014-01-01

    Liquid-air interface (LAI) corrosion has been a concern for causing leaks in the carbon steel tanks used for holding high-level radioactive liquid waste. To assist in understanding the mechanism of LAI corrosion, the kinetics of nitrate and nitrite reduction reactions were investigated electrochemically. Cyclic voltammetry and cathodic polarization measurements indicated that the nitrite reduction reaction exhibited faster kinetics than the nitrate reduction reaction at higher cathodic overpotential. However, the primary reduction reaction at the open circuit potential under aerated conditions was the oxygen reduction reaction. The reduction of residual oxygen was also the dominant cathodic reaction at open circuit potential in deaerated conditions. Moreover, the kinetics of oxygen reduction on steel electrodes were significantly influenced by the sample immersion conditions (partial vs. full) for aerated liquid nuclear waste simulants, but not for deaerated conditions. Lastly, the gaseous products formed during LAI corrosion were analyzed using the gas detector tube method and gas chromatography-mass spectrometry and found to contain NH 3 , NO 2 and NO. However, the results suggested that these products were caused by the local acidification generated by the hydrolysis of cations after LAI corrosion underwent extensive propagation, instead of being directly reduced in alkaline conditions. Thus, the results in this work showed that the kinetics of nitrate and nitrite reduction could not generate a salt concentration cell in the meniscus region to cause LAI corrosion

  19. Effects of Processing Temperature on Color Properties of Dry-Cured Hams Made without Nitrite

    Science.gov (United States)

    Parolari, Giovanni; Aguzzoni, Agnese; Toscani, Tania

    2016-01-01

    Dry cured hams were investigated for their ability to develop red color even at low temperature (3–4 °C) and in the absence of added nitrites; results were compared with those obtained from nitrite-free hams made at conventional warm maturing temperatures. Colorimetric parameters (L*, a*, b*, and hue) and concentration of the main pigments Zn protoporphyrin IX (ZnPP) and heme were measured at three stages of preparation (six, nine, and 12 months), showing that red color was successfully formed at low temperatures, though at a slower rate and less intensively than under warm conditions. Major differences in the pattern of color development were found with the two processing temperatures. While the typical features of an enzyme-dependent mechanism, with a progressive drop in enzyme activity paralleling the synthesis of Zn protoporphyrin IX, were observed at warm temperatures, the same did not occur in cold-made hams, where the enzyme activity was almost unchanged throughout the process. These results, along with data from a descriptive sensory analysis, are supportive of a non-enzymatic mechanism leading to ZnPP (hence the red color) under cold conditions, with an estimated three-month delay compared with nitrite-free hams manufactured in a warm maturing regimen. PMID:28231128

  20. Partial substitution of nitrite by chitosan and the effect on the quality properties of pork sausages

    Directory of Open Access Journals (Sweden)

    Mario García

    2011-06-01

    Full Text Available The aim of the study was to evaluate the influence of partial nitrite replacement by chitosan on the quality of Ham Visking (a type of pork sausages. Five Ham Visking formulations were elaborated modifying the sodium nitrite (0.011; 0.016 or 0.0212% and chitosan concentrations (0.25 or 0.5% in the products. Sausages were stored at 4 ºC and physicochemical, microbiological, and sensorial evaluations were performed in order to estimate their shelf life. Chitosan can be used in pork sausages without affecting ensory attributes such as color although the panelists detected textural differences among the samples with chitosan, which suggests that there is some influence of deacetylation degree of chitosan on the textural behavior of sausages which still needed to be explained for a successful application of chitosan in meat products. The reduction of residual sodium nitrite did not affect the color and flavor of such products, but the use of chitosan increasedsignificantly the shelf life of sausages.

  1. Humic-like Products Formation via the Reaction of Phenol with Nitrite in Ice Phase

    Science.gov (United States)

    Min, D. W.; Choi, W.

    2017-12-01

    Understanding the chemical nature of humic substances is very important but the origin of humic substances in nature is not well known. Therefore, elucidating the mechanisms leading to the generation of humic substances in nature is of great interests. It is believed that humic substances are produced from the transformation of natural organic matters, like lignin, by biological pathways. Recently, it has been reported that monomer molecules like quinones and sugars could be polymerized with amino compounds to form humic-like substances. This humification process is considered as a possible mechanism of humic substances production in the environment. In this work, we report the first observation on the formation of humic-like substances from the reaction between phenol and nitrite under a frozen state. In aqueous solution, nitrite slowly reacts with phenol, producing phenolic compounds like nitrophenol. Under frozen state, however, phenol reacted rapidly with nitrite and produced diverse organic compounds, like hydroquinone, dimerized phenolic substances, and much bigger molecules such as humic-like substances. The humic-like substances produced in ice are likely caused by the formation of phenolic radical and nitrosonium ion. This work may provide some insights into unknown pathways for the origin of humic substances especially in frozen environments.

  2. Determination of nitrite/nitrate in human biological material by the simple Griess reaction.

    Science.gov (United States)

    Guevara, I; Iwanejko, J; Dembińska-Kieć, A; Pankiewicz, J; Wanat, A; Anna, P; Gołabek, I; Bartuś, S; Malczewska-Malec, M; Szczudlik, A

    1998-06-22

    Since a number of pathological processes such as septic shock, inflammation, graft rejection, diabetes, etc. are associated with a release of nitric oxide (NO), rapid and accurate methods of monitoring of NO concentration are of interest. Various methods for measurement of nitrite and nitrate (NO2-, NO3- ) -- the stable metabolites of NO -- are commonly used for this purpose. In this paper we have shown that the proper Griess procedure for nitrite determination significantly increases the sensitivity of this method. This procedure, supplemented with deproteinization and reduction of nitrates to nitrites in the presence of NADPH-sensitive reductase, can be successfully applied for measurement of NOx levels in human body fluids (serum, urine and CSF). Deproteinization of samples with methanol/diethylether is required and does not influence the sensitivity of detection of NO metabolites. The recovery of the method is 88%+/-6% (n = 30). The NOx concentrations measured by this procedure ranged from 25.0 to 39.0 micromol/l in blood, 4.6 to 14.6 micromol/l in CSF and 0.37 to 2.52 mmol/l (adjusted to creatinine concentration) in urine. The coefficient of variation for this method was between 1.3-2.2%. This method can also be recommended for measurement of NOx produced by cells in tissue cell culture.

  3. Nitrite-induced acute kidney injury with secondary hyperparathyroidism: Case report and literature review.

    Science.gov (United States)

    Peng, Tao; Hu, Zhao; Yang, Xiangdong; Gao, Yanxia; Ma, Chengjun

    2018-02-01

    Acute kidney injury (AKI) with hyperparathyroidism caused by nitrite was rare, and renal function and parathyroid hormone (PTH) decreased to normal range after therapy. Acute kidney injury was diagnosed in a 40-year-old male with hyperparathyroidism and cyanosis of his hands and both forearms. The patient ate some recently pickled vegetables, and he experienced nausea, vomiting and diarrhoea without oliguria or anuria; Additionally, his hands and both forearms had a typical blue ash appearance. After admission, the laboratory findings indicated theincreasing serum creatinine (Scr) and parathyroid hormone (PTH). He was diagnosed as acute kidney injury with hyperparathyroidism caused by nitrite. The patient stopped eating the pickled vegetables and was given rehydration, added calories and other supportive therapy without any glucocorticoids. According to his clinical manifestations, laboratory findings and imaging results, the patient was diagnosed with acute kidney injury with secondary hyperparathyroidism. He was given symptomatic supportive care therapy. After one week, the serum creatinine, parathyroid hormone (PTH), hypercalcemia, hyperphosphatemia, proteinuria, and urine red blood cell values decreased to normal range. Nitrite-induced acute kidney injury with secondary hyperparathyroidism was relatively rare. After therapy, the function of the kidney and parathyroid returned to normal. This case suggests that detailed collection of medical history, physical examination and correct symptomatic treatment is very important.

  4. Calcium signals in olfactory neurons.

    Science.gov (United States)

    Tareilus, E; Noé, J; Breer, H

    1995-11-09

    Laser scanning confocal microscopy in combination with the fluorescent calcium indicators Fluo-3 and Fura-Red was employed to estimate the intracellular concentration of free calcium ions in individual olfactory receptor neurons and to monitor temporal and spatial changes in the Ca(2+)-level upon stimulation. The chemosensory cells responded to odorants with a significant increase in the calcium concentration, preferentially in the dendritic knob. Applying various stimulation paradigma, it was found that in a population of isolated cells, subsets of receptor neurons display distinct patterns of responsiveness.

  5. Why Calcium? How Calcium Became the Best Communicator*

    OpenAIRE

    Carafoli, Ernesto; Krebs, Joachim

    2016-01-01

    Calcium carries messages to virtually all important functions of cells. Although it was already active in unicellular organisms, its role became universally important after the transition to multicellular life. In this Minireview, we explore how calcium ended up in this privileged position. Most likely its unique coordination chemistry was a decisive factor as it makes its binding by complex molecules particularly easy even in the presence of large excesses of other cations,...

  6. Isomorfic Substitutions of Calcium by Strontium in Calcium Hydroxyapatite

    International Nuclear Information System (INIS)

    Christensen, Hilbert

    1962-12-01

    By means of homogeneous precipitation it has been possible to synthesize crystalline solid solutions of calcium strontium hydroxyapatite from aqueous solutions. The lattice constants for the solid solutions were measured in the range Ca 9 Sr(PO 4 ) 6 (OH) 2 - CaSr 9 (PO 4 ) 6 (OH) 2 . The investigations show that the discrimination of strontium against calcium is considerably smaller than reported elsewhere (1). Strontium is preferentially built into the c-axis direction of the apatite lattice

  7. Influence of dietary calcium on bone calcium utilization

    International Nuclear Information System (INIS)

    Farmer, M.; Roland, D.A. Sr.; Clark, A.J.

    1986-01-01

    In Experiment 1, 10 microCi 45 Ca/day were administered to 125 hens for 10 days. Hens were then allocated to five treatments with calcium levels ranging from .08 to 3.75% of the diet. In Experiment 2, hens with morning oviposition times were randomly allocated to 11 treatments that were periods of time postoviposition ranging from 6 hr to 24 hr, in 2-hr increments (Experiment 2). At the end of each 2-hr period, eggs from 25 hens were removed from the uterus. The 18-, 20-, and 22-hr treatments were replicated three times. In Experiment 3, hens were fed either ad libitum or feed was withheld the last 5 or 6 hr before oviposition. In Experiment 4, hens were fed 10 microCi of 45 Ca for 15 days to label skeletal calcium. Hens were divided into two groups and fed a .08 or 3.75% calcium diet for 2 days. On the second day, 25 hens fed the 3.75% calcium diet were intubated with 7 g of the same diet containing .5 g calcium at 1700, 2100, 0100, 0500, and 0700 hr. The measurements used were egg weight, shell weight, and 45 Ca content of the egg shell. Results indicated a significant linear or quadratic regression of dietary calcium levels on 45 Ca accumulation in eggshells and eggshell weight (Experiment 1). As the calcium level of the diet increased, eggshell weight increased and 45 Ca recovery decreased. Utilization of skeletal calcium for shell formation ranged from 28 to 96%. In Experiment 2, the rate of shell calcification was not constant throughout the calcification process but varied significantly

  8. The role of red blood cell S-nitrosation in nitrite bioactivation and its modulation by leucine and glucose

    Directory of Open Access Journals (Sweden)

    Nadeem Wajih

    2016-08-01

    Full Text Available Previous work has shown that red blood cells (RBCs reduce nitrite to NO under conditions of low oxygen. Strong support for the ability of red blood cells to promote nitrite bioactivation comes from using platelet activation as a NO-sensitive process. Whereas addition of nitrite to platelet rich plasma in the absence of RBCs has no effect on inhibition of platelet activation, when RBCs are present platelet activation is inhibited by an NO-dependent mechanism that is potentiated under hypoxia. In this paper, we demonstrate that nitrite bioactivation by RBCs is blunted by physiologically-relevant concentrations of nutrients including glucose and the important signaling amino acid leucine. Our mechanistic investigations demonstrate that RBC mediated nitrite bioactivation is largely dependent on nitrosation of RBC surface proteins. These data suggest a new expanded paradigm where RBC mediated nitrite bioactivation not only directs blood flow to areas of low oxygen but also to areas of low nutrients. Our findings could have profound implications for normal physiology as well as pathophysiology in a variety of diseases including diabetes, sickle cell disease, and arteriosclerosis.

  9. Low nitrous oxide production through nitrifier-denitrification in intermittent-feed high-rate nitritation reactors.

    Science.gov (United States)

    Su, Qingxian; Ma, Chun; Domingo-Félez, Carlos; Kiil, Anne Sofie; Thamdrup, Bo; Jensen, Marlene Mark; Smets, Barth F

    2017-10-15

    Nitrous oxide (N 2 O) production from autotrophic nitrogen conversion processes, especially nitritation systems, can be significant, requires understanding and calls for mitigation. In this study, the rates and pathways of N 2 O production were quantified in two lab-scale sequencing batch reactors operated with intermittent feeding and demonstrating long-term and high-rate nitritation. The resulting reactor biomass was highly enriched in ammonia-oxidizing bacteria, and converted ∼93 ± 14% of the oxidized ammonium to nitrite. The low DO set-point combined with intermittent feeding was sufficient to maintain high nitritation efficiency and high nitritation rates at 20-26 °C over a period of ∼300 days. Even at the high nitritation efficiencies, net N 2 O production was low (∼2% of the oxidized ammonium). Net N 2 O production rates transiently increased with a rise in pH after each feeding, suggesting a potential effect of pH on N 2 O production. In situ application of 15 N labeled substrates revealed nitrifier denitrification as the dominant pathway of N 2 O production. Our study highlights operational conditions that minimize N 2 O emission from two-stage autotrophic nitrogen removal systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Mechanism of pitting corrosion prevention by nitrite in carbon steel exposed to dilute salt solutions. 1998 annual progress report

    International Nuclear Information System (INIS)

    Zapp, P.E.; Zee, J. van.

    1998-01-01

    'The overall goal of this project is to develop a fundamental understanding of the role of nitrite in preventing the breakdown of protective oxide(s) on carbon steel and the onset of pitting. Pitting corrosion of carbon steel exposed to dilute alkaline salt solutions can be induced by nitrate, sulfate, and chloride ions and is prevented by sufficient concentration of nitrite. A significant example of this material/electrolyte system is the storage and processing of DOE''s high-level radioactive liquid waste in carbon steel tanks. Added nitrite in the waste has a considerable downstream impact on the immobilization of the waste in a stable glass form. Waste tank integrity and glass production efficiency may benefit from the fundamental understanding of nitrite''s role in preventing pitting. This report summarizes progress after approximately six months of effort in this three-year EMSP project. Initial experimental and theoretical work has focused on the electrochemical behavior of carbon steel in simplified non-radioactive solutions that simulate complex dilute radioactive waste solutions. These solutions contain corrosion-inducing species such as nitrate and chloride and the corrosion-inhibiting nitrite at moderately alkaline pHs. The electrochemical behavior of interest here is that of the open-circuit potential of the steel specimen at equilibrium in the experimental electrolyte and the measures of the steel''s passivity and passivity breakdown.'

  11. Association between dietary nitrate and nitrite intake and site-specific cancer risk: evidence from observational studies

    Science.gov (United States)

    Jia, Hui-Xun; Liang, Fei; Yuan, Jing; Zhu, Ji

    2016-01-01

    Epidemiological studies have reported inconsistent findings on the association between dietary nitrate and nitrite intake and cancer risk. We performed a meta-analysis of epidemiological studies to summarize available evidence on the association between dietary nitrate and nitrite intake and cancer risk from published prospective and case-control studies. PubMed database was searched to identify eligible publications through April 30th, 2016. Study-specific relative risks (RRs) with corresponding 95% confidence interval (CI) from individual studies were pooled by using random- or fixed- model, and heterogeneity and publication bias analyses were conducted. Data from 62 observational studies, 49 studies for nitrates and 51 studies for nitrites, including a total of 60,627 cancer cases were analyzed. Comparing the highest vs. lowest levels, dietary nitrate intake was inversely associated with gastric cancer risk (RR = 0.78; 95%CI = 0.67-0.91) with moderate heterogeneity (I2 = 42.3%). In contrast, dietary nitrite intake was positively associated with adult glioma and thyroid cancer risk with pooled RR of 1.21 (95%CI = 1.03-1.42) and 1.52 (95%CI = 1.12-2.05), respectively. No significant associations were found between dietary nitrate/nitrite and cancers of the breast, bladder, colorectal, esophagus, renal cell, non-Hodgkin lymphoma, ovarian, and pancreas. The present meta-analysis provided modest evidence that positive associations of dietary nitrate and negative associations of dietary nitrite with certain cancers. PMID:27486968

  12. The Nitrite-Scavenging Properties of Catechol, Resorcinol, and Hydroquinone: A Comparative Study on Their Nitration and Nitrosation Reactions.

    Science.gov (United States)

    Lu, Yunhao; Dong, Yanzuo; Li, Xueli; He, Qiang

    2016-10-14

    The nitration and nitrosation reactions of catechol, resorcinol, and hydroquinone (0.05 mmol/L) with sodium nitrite (0.05 mmol/L) at pH 3 and 37 °C were studied by using liquid chromatography and mass spectrometry (LC-MS) and atom charge analysis, which was aimed to provide chemical insight into the nitrite-scavenging behavior of polyphenols. The 3 benzenediols showed different mechanisms to scavenge nitrite due to their differences in hydroxyl position. Catechol was nitrated with 1 NO 2 group at the hydroxyl oxygen, and resorcinol was nitrosated with 2 NO groups at the C 2 and C 4 (or C 6 ) positions of the benzene ring. Hydroquinone could scavenge nitrite through both nitration and nitrosation mechanisms. The nitrated hydroquinone had 1 NO 2 group at the hydroxyl oxygen in the molecule, while the nitrosated 1 containing 2 NO groups at the benzene ring might have 3 structure probabilities. The results may provide a structure-activity understanding on the nitrite-scavenging property of polyphenols, so as to promote their application in the food industry for the removal of possibly toxic nitrites found in many vegetables and often in processed meat products. © 2016 Institute of Food Technologists®.

  13. Evaluation of Total Nitrite Pattern Visualization as an Improved Method for Gunshot Residue Detection and its Application to Casework Samples.

    Science.gov (United States)

    Berger, Jason; Upton, Colin; Springer, Elyah

    2018-04-23

    Visualization of nitrite residues is essential in gunshot distance determination. Current protocols for the detection of nitrites include, among other tests, the Modified Griess Test (MGT). This method is limited as nitrite residues are unstable in the environment and limited to partially burned gunpowder. Previous research demonstrated the ability of alkaline hydrolysis to convert nitrates to nitrites, allowing visualization of unburned gunpowder particles using the MGT. This is referred to as Total Nitrite Pattern Visualization (TNV). TNV techniques were modified and a study conducted to streamline the procedure outlined in the literature to maximize the efficacy of the TNV in casework, while reducing the required time from 1 h to 5 min, and enhancing effectiveness on blood-soiled samples. The TNV method was found to provide significant improvement in the ability to detect significant nitrite residues, without sacrificing efficiency, that would allow for the determination of the muzzle-to-target distance. © 2018 American Academy of Forensic Sciences.

  14. Nitrite inhalant use among young gay and bisexual men in Vancouver during a period of increasing HIV incidence

    Directory of Open Access Journals (Sweden)

    Mattheis Kelly

    2007-03-01

    Full Text Available Abstract Background Nitrite inhalants ("poppers" are peripheral vasodilators which, since the beginning of the epidemic, have been known to increase risk for acquiring HIV infection among men who have sex with men (MSM. However, few studies in recent years have characterized use. From 1999 to 2004, new HIV diagnoses among MSM in British Columbia increased 78%, prompting us to examine the prevalence and correlates of this modifiable HIV risk factor. Methods Self-administered questionnaires were completed between October 2002 and May 2004 as part of an open cohort study of HIV-seronegative young MSM. We measured nitrite inhalant use during the previous year and use during sexual encounters with casual partners specifically. Correlates of use were identified using odds ratios. Results Among 354 MSM surveyed, 31.6% reported any use during the previous year. Nitrite inhalant use during sexual encounters was reported by 22.9% of men and was strongly associated with having casual partners, with greater numbers of casual partners (including those with positive or unknown serostatus and with anal intercourse with casual partners. Nitrite inhalant use was not associated with non-use of condoms with casual sexual partners per se. Conclusion Contemporary use of nitrite inhalants amongst young MSM is common and a strong indicator of anal intercourse with casual sexual partners. Since use appears to increase the probability of infection following exposure to HIV, efforts to reduce the use of nitrite inhalants among MSM should be a very high priority among HIV prevention strategies.

  15. Extreme nitrite tolerance in the clown knifefish Chitala ornata is linked to up-regulation of methaemoglobin reductase activity

    DEFF Research Database (Denmark)

    Le Thi Hong Gam; Jensen, Frank Bo; Damsgaard, Christian

    2017-01-01

    and fell towards control values during the last half of the exposure period. Plasma nitrate, in contrast, rose continuously, reflecting detoxification of nitrite to nitrate. MetHb generated from the reaction between nitrite and erythrocyte Hb reached 38% at day 2, but then decreased to 17% by the end......The clown knifefish is a facultative air breather, which is widely farmed in freshwater ponds in Vietnam. Here we report a very high nitrite tolerance (96h LC50 of 7.82mM) in this species and examine the effects of 1mM (LC5) and 2.5mM (LC10) ambient nitrite on haemoglobin (Hb) derivatives......, electrolyte levels, acid-base status, and total body water content during 7days of exposure. Furthermore, we tested the hypothesis that erythrocyte methaemoglobin (metHb) reductase activity is upregulated by nitrite exposure. Plasma nitrite levels increased for 2-3days but stayed below environmental levels...

  16. Synthesis, characterization and nitrite ion sensing performance of reclaimable composite samples through a core-shell structure

    Science.gov (United States)

    Cui, Xiao; Yuqing, Zhao; Cui, Jiantao; Zheng, Qian; Bo, Wang

    2018-02-01

    The following paper reported and discussed a nitrite ion optical sensing platform based on a core-shell structure, using superamagnetic nanoparticles as the core, a silica molecular sieve MCM-41 as the shell and two rhodamine derivatives as probe, respectively. This superamagnetic core made this sensing platform reclaimable after finishing nitrite ion sensing procedure. This sensing platform was carefully characterized by means of electron microscopy images, porous structure analysis, magnetic response, IR spectra and thermal stability analysis. Detailed analysis suggested that the emission of these composite samples was quenchable by nitrite ion, showing emission turn off effect. A static sensing mechanism based on an additive reaction between chemosensors and nitrite ion was proposed. These composite samples followed Demas quenching equation against different nitrite ion concentrations. Limit of detection value was obtained as low as 0.4 μM. It was found that, after being quenched by nitrite ion, these composite samples could be reclaimed and recovered by sulphamic acid, confirming their recyclability.

  17. Colour formation in fermented sausages by meat-associated staphylococci with different nitrite- and nitrate-reductase activities.

    Science.gov (United States)

    Gøtterup, Jacob; Olsen, Karsten; Knøchel, Susanne; Tjener, Karsten; Stahnke, Louise H; Møller, Jens K S

    2008-04-01

    Three Staphylococcus strains, S. carnosus, S. simulans and S. saprophyticus, selected due to their varying nitrite and/or nitrate-reductase activities, were used to initiate colour formation during sausage fermentation. During fermentation of sausages with either nitrite or nitrate added, colour was followed by L(∗)a(∗)b measurements and the content of nitrosylmyoglobin (MbFe(II)NO) quantified by electron spin resonance (ESR). MbFe(II)NO was rapidly formed in sausages with added nitrite independent of the presence of nitrite reducing bacteria, whereas the rate of MbFe(II)NO formation in sausages with added nitrate depended on the specific Staphylococcus strain. Strains with high nitrate-reductase activity showed a significantly faster rate of pigment formation, but other factors were of influence as well. Product stability for the sliced, packaged sausage was evaluated as surface colour and oxidation by autofluorescence and hexanal content, respectively. No significant direct effect of the Staphylococcus addition was observed, however, there was a clear correspondence between high initial amount of MbFe(II)NO in the different sausages and the colour stability during storage. Autofluorescence data correlated well with hexanal content, and may be used as predictive tools. Overall, nitrite- and nitrate-reductase activities of Staphylococcus strains in nitrite-cured sausages were of limited importance regarding colour development, while in nitrate-cured sausages strains with higher nitrate reductase activity were crucial for ensuring optimal colour formation during initial fermentation stages.

  18. Effects of nitrite exposure on functional haemoglobin levels, bimodal respiration, and swimming performance in the facultative air-breathing fish Pangasianodon hypophthalmus

    Energy Technology Data Exchange (ETDEWEB)

    Lefevre, Sjannie, E-mail: sjannie.lefevre@biology.au.dk [Zoophysiology, Department of Biological Sciences, Aarhus University, Aarhus (Denmark); Jensen, Frank B. [Department of Biology, University of Southern Denmark, Odense (Denmark); Huong, Do.T.T. [College of Aquaculture and Fisheries, Can Tho University, Can Tho City (Viet Nam); Wang, Tobias [Zoophysiology, Department of Biological Sciences, Aarhus University, Aarhus (Denmark); Phuong, Nguyen T. [College of Aquaculture and Fisheries, Can Tho University, Can Tho City (Viet Nam); Bayley, Mark [Zoophysiology, Department of Biological Sciences, Aarhus University, Aarhus (Denmark)

    2011-07-15

    In this study we investigated nitrite (NO{sub 2}{sup -}) effects in striped catfish, a facultative air-breather. Fish were exposed to 0, 0.4, and 0.9 mM nitrite for 0, 1, 2, 4, and 7 days, and levels of functional haemoglobin, methaemoglobin (metHb) and nitrosyl haemoglobin (HbNO) were assessed using spectral deconvolution. Plasma concentrations of nitrite, nitrate, chloride, potassium, and sodium were also measured. Partitioning of oxygen consumption was determined to reveal whether elevated metHb (causing functional hypoxia) induced air-breathing. The effects of nitrite on maximum oxygen uptake (MO{sub 2max}) and critical swimming speed (U{sub crit}) were also assessed. Striped catfish was highly tolerant to nitrite exposure, as reflected by a 96 h LC{sub 50} of 1.65 mM and a moderate nitrite uptake into the blood. Plasma levels of nitrite reached a maximum after 1 day of exposure, and then decreased, never exceeding ambient levels. MetHb, HbNO and nitrate (a nitrite detoxification product) also peaked after 1 day and then decreased. Only high levels of nitrite and metHb caused reductions in MO{sub 2max} and U{sub crit}. The response of striped catfish contrasts with that seen in most other fish species and discloses efficient mechanisms of combating nitrite threats. Furthermore, even though striped catfish is an efficient air-breather, this species has the ability to sustain aerobic scope and swimming performance without air-breathing, even when faced with nitrite-induced reductions in blood oxygen carrying capacity. Our study is the first to confirm that high levels of nitrite and metHb reduce MO{sub 2max} and thereby aerobic scope, while more moderate elevations fail to do so. Further studies are needed to elucidate the mechanisms underlying the low nitrite accumulation in striped catfish.

  19. Effects of nitrite exposure on functional haemoglobin levels, bimodal respiration, and swimming performance in the facultative air-breathing fish Pangasianodon hypophthalmus.

    Science.gov (United States)

    Lefevre, Sjannie; Jensen, Frank B; Huong, Do T T; Wang, Tobias; Phuong, Nguyen T; Bayley, Mark

    2011-07-01

    In this study we investigated nitrite (NO₂⁻) effects in striped catfish, a facultative air-breather. Fish were exposed to 0, 0.4, and 0.9 mM nitrite for 0, 1, 2, 4, and 7 days, and levels of functional haemoglobin, methaemoglobin (metHb) and nitrosyl haemoglobin (HbNO) were assessed using spectral deconvolution. Plasma concentrations of nitrite, nitrate, chloride, potassium, and sodium were also measured. Partitioning of oxygen consumption was determined to reveal whether elevated metHb (causing functional hypoxia) induced air-breathing. The effects of nitrite on maximum oxygen uptake (MO(2max)) and critical swimming speed (U(crit)) were also assessed. Striped catfish was highly tolerant to nitrite exposure, as reflected by a 96 h LC₅₀ of 1.65 mM and a moderate nitrite uptake into the blood. Plasma levels of nitrite reached a maximum after 1 day of exposure, and then decreased, never exceeding ambient levels. MetHb, HbNO and nitrate (a nitrite detoxification product) also peaked after 1 day and then decreased. Only high levels of nitrite and metHb caused reductions in MO(2max) and U(crit). The response of striped catfish contrasts with that seen in most other fish species and discloses efficient mechanisms of combating nitrite threats. Furthermore, even though striped catfish is an efficient air-breather, this species has the ability to sustain aerobic scope and swimming performance without air-breathing, even when faced with nitrite-induced reductions in blood oxygen carrying capacity. Our study is the first to confirm that high levels of nitrite and metHb reduce MO(2max) and thereby aerobic scope, while more moderate elevations fail to do so. Further studies are needed to elucidate the mechanisms underlying the low nitrite accumulation in striped catfish. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. Effects of nitrite exposure on functional haemoglobin levels, bimodal respiration, and swimming performance in the facultative air-breathing fish Pangasianodon hypophthalmus

    International Nuclear Information System (INIS)

    Lefevre, Sjannie; Jensen, Frank B.; Huong, Do.T.T.; Wang, Tobias; Phuong, Nguyen T.; Bayley, Mark

    2011-01-01

    In this study we investigated nitrite (NO 2 - ) effects in striped catfish, a facultative air-breather. Fish were exposed to 0, 0.4, and 0.9 mM nitrite for 0, 1, 2, 4, and 7 days, and levels of functional haemoglobin, methaemoglobin (metHb) and nitrosyl haemoglobin (HbNO) were assessed using spectral deconvolution. Plasma concentrations of nitrite, nitrate, chloride, potassium, and sodium were also measured. Partitioning of oxygen consumption was determined to reveal whether elevated metHb (causing functional hypoxia) induced air-breathing. The effects of nitrite on maximum oxygen uptake (MO 2max ) and critical swimming speed (U crit ) were also assessed. Striped catfish was highly tolerant to nitrite exposure, as reflected by a 96 h LC 50 of 1.65 mM and a moderate nitrite uptake into the blood. Plasma levels of nitrite reached a maximum after 1 day of exposure, and then decreased, never exceeding ambient levels. MetHb, HbNO and nitrate (a nitrite detoxification product) also peaked after 1 day and then decreased. Only high levels of nitrite and metHb caused reductions in MO 2max and U crit . The response of striped catfish contrasts with that seen in most other fish species and discloses efficient mechanisms of combating nitrite threats. Furthermore, even though striped catfish is an efficient air-breather, this species has the ability to sustain aerobic scope and swimming performance without air-breathing, even when faced with nitrite-induced reductions in blood oxygen carrying capacity. Our study is the first to confirm that high levels of nitrite and metHb reduce MO 2max and thereby aerobic scope, while more moderate elevations fail to do so. Further studies are needed to elucidate the mechanisms underlying the low nitrite accumulation in striped catfish.

  1. Ingested nitrate and nitrite, disinfection by-products, and pancreatic cancer risk in postmenopausal women.

    Science.gov (United States)

    Quist, Arbor J L; Inoue-Choi, Maki; Weyer, Peter J; Anderson, Kristin E; Cantor, Kenneth P; Krasner, Stuart; Freeman, Laura E Beane; Ward, Mary H; Jones, Rena R

    2018-01-15

    Nitrate and nitrite are precursors of N-nitroso compounds (NOC), probable human carcinogens that cause pancreatic tumors in animals. Disinfection by-products (DBP) exposures have also been linked with digestive system cancers, but few studies have evaluated relationships with pancreatic cancer. We investigated the association of pancreatic cancer with these drinking water contaminants and dietary nitrate/nitrite in a cohort of postmenopausal women in Iowa (1986-2011). We used historical monitoring and treatment data to estimate levels of long-term average nitrate and total trihalomethanes (TTHM; the sum of the most prevalent DBP class) and the duration exceeding one-half the maximum contaminant level (>½ MCL; 5 mg/L nitrate-nitrogen, 40 µg/L TTHM) among participants on public water supplies (PWS) >10 years. We estimated dietary nitrate and nitrite intakes using a food frequency questionnaire. We computed hazard ratios (HR) and 95% confidence intervals (CI) using Cox regression and evaluated nitrate interactions with smoking and vitamin C intake. We identified 313 cases among 34,242 women, including 152 with >10 years PWS use (N = 15,710). Multivariable models of average nitrate showed no association with pancreatic cancer (HR p95 vs . Q1  = 1.16, 95% CI: 0.51-2.64). Associations with average TTHM levels were also null (HR Q4 vs . Q1  = 0.70, 95% CI:0.42-1.18). We observed no trend with increasing years of exposure to either contaminant at levels >½ MCL. Positive associations were suggested in the highest dietary nitrite intake from processed meat (HR p95 vs . Q1  = 1.66, 95% CI 1.00-2.75;p trend  = 0.05). We found no interactions of nitrate with known modifiers of endogenous NOC formation. Our results suggest that nitrite intake from processed meat may be a risk factor for pancreatic cancer. 2017 UICC.

  2. Acidified nitrite inhibits proliferation of Listeria monocytogenes - Transcriptional analysis of a preservation method.

    Science.gov (United States)

    Müller-Herbst, Stefanie; Wüstner, Stefanie; Kabisch, Jan; Pichner, Rohtraud; Scherer, Siegfried

    2016-06-02

    Sodium nitrite (NaNO2) is added as a preservative during raw meat processing such as raw sausage production to inhibit growth of pathogenic bacteria. In the present study it was shown in challenge assays that the addition of sodium nitrite indeed inhibited growth and survival of Listeria monocytogenes in short-ripened spreadable raw sausages. Furthermore, in vitro growth analyses were performed, which took into account combinations of various parameters of the raw sausage ripening process like temperature, oxygen availability, pH, NaCl concentration, and absence or presence of NaNO2. Data based on 300 growth conditions revealed that the inhibitory effect of nitrite was most prominent in combination with acidification, a combination that is also achieved during short-ripened spreadable raw sausage production. At pH6.0 and below, L. monocytogenes was unable to replicate in the presence of 200mg/l NaNO2. During the adaptation of L. monocytogenes to acidified nitrite stress (pH6.0, 200mg/l NaNO2) in comparison to acid exposure only (pH6.0, 0mg/l NaNO2), a massive transcriptional adaptation was observed using microarray analyses. In total, 202 genes were up-regulated and 204 genes were down-regulated. In accordance with growth inhibition, a down-regulation of genes encoding for proteins which are involved in central cellular processes, like cell wall/membrane/envelope biogenesis, translation and ribosomal structure and biogenesis, transcription, and replication, recombination and repair, was observed. Among the up-regulated genes the most prominent group belonged to poorly characterized genes. A considerable fraction of the up-regulated genes has been shown previously to be up-regulated intracellularly in macrophages, after exposure to acid shock or to be part of the SigB regulon. These data indicate that the adaptation to acidified nitrite partly overlaps with the adaptation to stress conditions being present during host colonization. Copyright © 2016 Elsevier B

  3. Relevance of nitrate and nitrite in dry-cured ham and their effects on aroma development

    Directory of Open Access Journals (Sweden)

    Flores, Mónica

    2009-07-01

    Full Text Available Potassium and sodium salts of nitrite (E 249 and E 250 and nitrate (E 251 and E 252 are authorised for use under certain levels in several foodstuffs such as non-heat-treated, cured and dried meat products, other cured meat products, canned meat products and bacon. The key point in the use of nitrate and nitrite as preservatives is to find a balance between ensuring the microbiological safety of the ham and keeping as low as possible the level of nitrosamines in the final product. Nitrites and nitrates are authorised as additives for dry-cured ham in the Directive 2006/52/EC of 5 July 2006 that modifies previous Council Directive 95/2/EC on food additives other than colours and sweeteners. The effect of nitrate and its reduction to nitrite in controlling the lipid oxidation process during the ham ripening is very important for the development of the characteristic cured flavour. The main benefits and drawbacks of the use of nitrites and nitrates in dry-cured ham and how these levels may affect its flavour are discussed in this manuscript.Las sales sódica y potásica del nitrito (E249 y E250 y del nitrato (E251 y E252 están autorizados para su uso en los productos cárnicos, secos, curados y no tratados por el calor, otros productos cárnicos curados, productos cárnicos enlatados y bacon. El punto esencial en el uso de nitrato y nitrito como conservantes consiste en encontrar un balance entre el aseguramiento de la seguridad microbiológica del jamón y mantener el nivel de nitrosaminas tan bajo como sea posible. Los nitratos y nitritos están autorizados como aditivos en el jamón curado según la Directiva Europea 2006/52/EC de 5 de Julio de 2006 que modificaba la previa Directiva Europea 95/2/EC de aditivos alimentarios distintos a los colorantes y edulcorantes. El efecto del nitrato y su reducción a nitrito para controlar la oxidación de los lípidos durante la maduración del jamón es muy importante para el desarrollo del caracter

  4. 21 CFR 172.410 - Calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium silicate. 172.410 Section 172.410 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Agents § 172.410 Calcium silicate. Calcium silicate, including synthetic calcium silicate, may be safely...

  5. A Crash Course in Calcium Channels.

    Science.gov (United States)

    Zamponi, Gerald W

    2017-12-20

    Much progress has been made in understanding the molecular physiology and pharmacology of calcium channels. Recently, there have been tremendous advances in learning about calcium channel structure and function through crystallography and cryo-electron microscopy studies. Here, I will give an overview of our knowledge about calcium channels, and highlight two recent studies that give important insights into calcium channel structure.

  6. Calcium-sensing beyond neurotransmitters

    DEFF Research Database (Denmark)

    Gustavsson, Natalia; Han, Weiping

    2009-01-01

    Neurotransmitters, neuropeptides and hormones are released through the regulated exocytosis of SVs (synaptic vesicles) and LDCVs (large dense-core vesicles), a process that is controlled by calcium. Synaptotagmins are a family of type 1 membrane proteins that share a common domain structure. Most....... Also, we discuss potential roles of synaptotagmins in non-traditional endocrine systems....... synaptotagmins are located in brain and endocrine cells, and some of these synaptotagmins bind to phospholipids and calcium at levels that trigger regulated exocytosis of SVs and LDCVs. This led to the proposed synaptotagmin-calcium-sensor paradigm, that is, members of the synaptotagmin family function...... as calcium sensors for the regulated exocytosis of neurotransmitters, neuropeptides and hormones. Here, we provide an overview of the synaptotagmin family, and review the recent mouse genetic studies aimed at understanding the functions of synaptotagmins in neurotransmission and endocrine-hormone secretion...

  7. Calcium phosphates for biomedical applications

    Directory of Open Access Journals (Sweden)

    Maria Canillas

    2017-05-01

    Full Text Available The history of calcium phosphates in the medicine field starts in 1769 when the first evidence of its existence in the bone tissue is discovered. Since then, the interest for calcium phosphates has increased among the scientific community. Their study has been developed in parallel with new advances in materials sciences, medicine or tissue engineering areas. Bone tissue engineering is the field where calcium phosphates have had a great importance. While the first bioceramics are selected according to bioinert, biocompatibility and mechanical properties with the aim to replace bone tissue damaged, calcium phosphates open the way to the bone tissue regeneration challenge. Nowadays, they are present in the majority of commercial products directed to repair or regenerate damaged bone tissue. Finally, in the last few decades, they have been suggested and studied as drug delivering devices and as vehicles of DNA and RNA for the future generation therapies.

  8. Functions of vitamin D / Calcium

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Excitation-contraction coupling,. Cardiac functions. Hormonal secretion. Control of enzymatic reactions. Mitotic division. Maintenance of cell integrity. Ciliary motility. Notes: Calcium is a vital second messenger.

  9. Calcium signals in planetary embryos

    Science.gov (United States)

    Morbidelli, Alessandro

    2018-03-01

    The calcium-isotope composition of planetary bodies in the inner Solar System correlates with the masses of such objects. This finding could have implications for our understanding of how the Solar System formed.

  10. Calcium homeostasis in diabetes mellitus.

    Science.gov (United States)

    Ahn, Changhwan; Kang, Ji-Houn; Jeung, Eui-Bae

    2017-09-30

    Diabetes mellitus (DM) is becoming a lifestyle-related pandemic disease. Diabetic patients frequently develop electrolyte disorders, especially diabetic ketoacidosis or nonketotic hyperglycemic hyperosmolar syndrome. Such patients show characteristic potassium, magnesium, phosphate, and calcium depletion. In this review, we discuss a homeostatic mechanism that links calcium and DM. We also provide a synthesis of the evidence in favor or against this linking mechanism by presenting recent clinical indications, mainly from veterinary research. There are consistent results supporting the use of calcium and vitamin D supplementation to reduce the risk of DM. Clinical trials support a marginal reduction in circulating lipids, and some meta-analyses support an increase in insulin sensitivity, following vitamin D supplementation. This review provides an overview of the calcium and vitamin D disturbances occurring in DM and describes the underlying mechanisms. Such elucidation will help indicate potential pathophysiology-based precautionary and therapeutic approaches and contribute to lowering the incidence of DM.

  11. Calcium phosphates for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Canillas, M.; Pena, P.; Aza, A.H. de; Rodriguez, M.A.

    2017-07-01

    The history of calcium phosphates in the medicine field starts in 1769 when the first evidence of its existence in the bone tissue is discovered. Since then, the interest for calcium phosphates has increased among the scientific community. Their study has been developed in parallel with new advances in materials sciences, medicine or tissue engineering areas. Bone tissue engineering is the field where calcium phosphates have had a great importance. While the first bioceramics are selected according to bioinert, biocompatibility and mechanical properties with the aim to replace bone tissue damaged, calcium phosphates open the way to the bone tissue regeneration challenge. Nowadays, they are present in the majority of commercial products directed to repair or regenerate damaged bone tissue. Finally, in the last few decades, they have been suggested and studied as drug delivering devices and as vehicles of DNA and RNA for the future generation therapies. (Author)

  12. Calcium signaling in liver.

    Science.gov (United States)

    Gaspers, Lawrence D; Thomas, Andrew P

    2005-01-01

    In hepatocytes, hormones linked to the formation of the second messenger inositol 1,4,5-trisphosphate (InsP3) evoke transient increases or spikes in cytosolic free calcium ([Ca2+]i), that increase in frequency with the agonist concentration. These oscillatory Ca2+ signals are thought to transmit the information encoded in the extracellular stimulus to down-stream Ca2+-sensitive metabolic processes. We have utilized both confocal and wide field fluorescence microscopy techniques to study the InsP3-dependent signaling pathway at the cellular and subcellular levels in the intact perfused liver. Typically InsP3-dependent [Ca2+]i spikes manifest as Ca2+ waves that propagate throughout the entire cytoplasm and nucleus, and in the intact liver these [Ca2+]i increases are conveyed through gap junctions to encompass entire lobular units. The translobular movement of Ca2+ provides a means to coordinate the function of metabolic zones of the lobule and thus, liver function. In this article, we describe the characteristics of agonist-evoked [Ca2+]i signals in the liver and discuss possible mechanisms to explain the propagation of intercellular Ca2+ waves in the intact organ.

  13. Effects of diphosphonate on kidney calcium content and duodenal absorption of 45calcium

    International Nuclear Information System (INIS)

    Goulding, A.; Cameron, V.

    1978-01-01

    In rats the relationships between EHDP-induced changes in serum calcium concentration, kidney calcium content and duodenal transport of 45 calcium were studied. Body weights and kidney weights were similar in all groups. EHDP administration was associated with an increase in serum calcium concentration and kidney calcium content, and a decrease in duodenal 45 calcium transport. In the EHDP-treated rats, there was a significant negative correlation between kidney calcium concentration and duodenal 45 calcium transport but no correlation between either kidney calcium content and serum calcium concentration (r = 0.116) or between serum calcium concentration and duodenal 45 calcium transport (r = 0.02). Further experiments will be needed to determine whether the demonstrated increase in kidney calcium content induced by EHDP administration was the cause of, or was secondary to, inhibition of 1, 25(OH) 2 D 3 synthesis. (orig./AJ) [de

  14. Research of calcium oxide hydration in calcium nitrate solutions

    Directory of Open Access Journals (Sweden)

    M.A. Oliynyk

    2016-09-01

    Full Text Available Mineral fertilizers are one of the important factors of agriculture intensification and increasing of food products quantity. The volume of fertilizers production and its domestic consumption in Ukraine indicate that nitrogen fertilizer using only comes nearer to the required number of science-based. One of the most widespread artificial fertilizers is the calcium nitrate. Aim: The aim is to study and theoretically substantiate the processes occurring in the preparation of suspensions of calcium hydroxide Са(ОН2 in solution of calcium nitrate Ca(NО32. Materials and Methods: The technical calcium oxide (quicklime DSTU BV.2.7-90-99, solutions of calcium nitrate of 15, 20, 25, 30, 35 and 40% Ca(NО32 concentrations were used in the work. The content of lime in the preparation of a suspension in the solution changed (in terms of calcium oxide CaO from 150 g/dm3 to the maximum possible. Each of these solutions saturated at 40°С in lime to maximum concentration. Suitable for use in these experiments and in the technology of calcium nitrate obtaining are considered the solutions (suspensions that within 12 hours did not lose their mobility (transportability. Results: The experimental results show that increasing of the concentration of calcium nitrate in solution within the range 15...40%, the amount of lime that you can put into the solution without loss of transportability decreases. Further increasing of lime quantity in solutions concentrations causes to its solidifying, loss of mobility (transportability. Calculations showed that in the presence of calcium nitrate the solubility of Са(ОН2 is reduced nearly by order that can lead to the formation of calcium oxide CaO the solid phase Са(ОН2 on the surface, which also can form hydrogen bonds with the components of the solution. As the probability of formation of hydrogen bonds in solutions is high, there is a possibility of formation of clusters.

  15. Calcium Orthophosphate Cements and Concretes

    Directory of Open Access Journals (Sweden)

    Sergey V. Dorozhkin

    2009-03-01

    Full Text Available In early 1980s, researchers discovered self-setting calcium orthophosphate cements, which are a bioactive and biodegradable grafting material in the form of a powder and a liquid. Both phases form after mixing a viscous paste that after being implanted, sets and hardens within the body as either a non-stoichiometric calcium deficient hydroxyapatite (CDHA or brushite, sometimes blended with unreacted particles and other phases. As both CDHA and brushite are remarkably biocompartible and bioresorbable (therefore, in vivo they can be replaced with newly forming bone, calcium orthophosphate cements represent a good correction technique for non-weight-bearing bone fractures or defects and appear to be very promising materials for bone grafting applications. Besides, these cements possess an excellent osteoconductivity, molding capabilities and easy manipulation. Furthermore, reinforced cement formulations are available, which in a certain sense might be described as calcium orthophosphate concretes. The concepts established by calcium orthophosphate cement pioneers in the early 1980s were used as a platform to initiate a new generation of bone substitute materials for commercialization. Since then, advances have been made in the composition, performance and manufacturing; several beneficial formulations have already been introduced as a result. Many other compositions are in experimental stages. In this review, an insight into calcium orthophosphate cements and concretes, as excellent biomaterials suitable for both dental and bone grafting application, has been provided.

  16. 21 CFR 184.1207 - Calcium lactate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium lactate. 184.1207 Section 184.1207 Food and... Substances Affirmed as GRAS § 184.1207 Calcium lactate. (a) Calcium lactate (C6H10CaO6.xH2O, where x is any... calcium carbonate or calcium hydroxide. (b) The ingredient meets the specifications of the Food Chemicals...

  17. Evolution of nitrate and nitrite during the processing of dry-cured ham with partial replacement of NaCl by other chloride salts.

    Science.gov (United States)

    Armenteros, Mónica; Aristoy, María-Concepción; Toldrá, Fidel

    2012-07-01

    Nitrate and nitrite are commonly added to dry-cured ham to provide protection against pathogen microorganisms, especially Clostridium botulinum. Both nitrate and nitrite were monitored with ion chromatography in dry-cured hams salted with different NaCl formulations (NaCl partially replaced by KCl and/or CaCl(2), and MgCl(2)). Nitrate, that is more stable than nitrite, diffuses into the ham and acts as a reservoir for nitrite generation. A correct nitrate and nitrite penetration was detected from the surface to the inner zones of the hams throughout its processing, independently of the salt formulation. Nitrate and nitrite achieved similar concentrations, around 37 and 2.2 ppm, respectively in the inner zones of the ham for the three assayed salt formulations at the end of the process, which are in compliance with European regulations. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. Amperometric nitrite sensor based on a glassy carbon electrode modified with multi-walled carbon nanotubes and poly(toluidine blue)

    International Nuclear Information System (INIS)

    Dai, Juan; Deng, Fei; He, Shuang; Deng, Dongli; Yuan, Yali; Zhang, Jinzhong

    2016-01-01

    An amperometric nitrite sensor modified with multi-walled carbon nanotubes (MWCNTs) and poly(toluidine blue) (PTB) on glassy carbon electrode was constructed. The surface morphology of the composite- modified electrode was characterized by scanning electron microscopy, and the electrochemical response behavior and electrocatalytic oxidation mechanism of nitrite were investigated by cyclic voltammetry. The high surface-to-volume ratio of MWCNTs and PTB brings the electrochemical sensing unit and nitrite in full contact. This renders the electrochemical response extremely sensitive to nitrite. Under the optimal measurement conditions and a working voltage of 0.73 V (vs. SCE), a linear relationship is obtained between the oxidation peak current and nitrite concentration in the range of 39 nM–1.1 mM, and the limit of detection is lowered to 19 nM (at an S/N ratio of 3). The sensor was successfully applied to the determination of nitrite in greenhouse soils. (author)

  19. Comparison of Valsalva Maneuver, Amyl Nitrite, and Exercise Echocardiography to Demonstrate Latent Left Ventricular Outflow Obstruction in Hypertrophic Cardiomyopathy.

    Science.gov (United States)

    Ayoub, Chadi; Geske, Jeffrey B; Larsen, Carolyn M; Scott, Christopher G; Klarich, Kyle W; Pellikka, Patricia A

    2017-12-15

    Guidelines recommend exercise stress echocardiogram (ESE) for patients with hypertrophic cardiomyopathy (HC) if a 50 mm Hg gradient is not present at rest or provoked with Valsalva or amyl nitrite, to direct medical and surgical management. However, no study has directly compared all 3 methods. We sought to evaluate efficacy and degree of provocation of left ventricular outflow gradients by ESE, and compare with Valsalva and amyl nitrite. In patients with HC between 2002 and 2015, resting echocardiograms and ESEs within 1 year were retrospectively reviewed. Gradients elicited by each provocation method were compared. Rest and ESE were available in 97 patients (mean age 54 ± 18 years, 57% male); 78 underwent Valsalva maneuver and 41 amyl nitrite provocation. Median gradients (interquartile range) were 10 mm Hg (7,19) at rest, 16 mm Hg (9,34) with Valsalva, 23 mm Hg (13,49) with amyl nitrite, and 26 mm Hg (13,58) with ESE. ESE and amyl nitrite were able to provoke obstruction (≥30 mm Hg) and severe obstruction (≥50 mm Hg) more frequently than Valsalva. In patients with resting gradient <30 mm Hg (n = 83), provocation maneuvers demonstrated dynamic obstruction in 51%; in those with Valsalva gradient <30 mm Hg (n = 57), ESE or amyl nitrite provoked a gradient in 44%; and in those with amyl nitrite gradient <30 mm Hg (n = 20), ESE provoked a gradient in 29%. No demographic or baseline echocardiographic parameter predicted provocable obstruction. In conclusion, ESE is clinically useful; however, different provocation maneuvers may be effective in different patients with HC, and all maneuvers may be required to provoke dynamic obstruction in symptomatic patients. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Long-term dietary nitrite and nitrate deficiency causes the metabolic syndrome, endothelial dysfunction and cardiovascular death in mice.

    Science.gov (United States)

    Kina-Tanada, Mika; Sakanashi, Mayuko; Tanimoto, Akihide; Kaname, Tadashi; Matsuzaki, Toshihiro; Noguchi, Katsuhiko; Uchida, Taro; Nakasone, Junko; Kozuka, Chisayo; Ishida, Masayoshi; Kubota, Haruaki; Taira, Yuji; Totsuka, Yuichi; Kina, Shin-Ichiro; Sunakawa, Hajime; Omura, Junichi; Satoh, Kimio; Shimokawa, Hiroaki; Yanagihara, Nobuyuki; Maeda, Shiro; Ohya, Yusuke; Matsushita, Masayuki; Masuzaki, Hiroaki; Arasaki, Akira; Tsutsui, Masato

    2017-06-01

    Nitric oxide (NO) is synthesised not only from L-arginine by NO synthases (NOSs), but also from its inert metabolites, nitrite and nitrate. Green leafy vegetables are abundant in nitrate, but whether or not a deficiency in dietary nitrite/nitrate spontaneously causes disease remains to be clarified. In this study, we tested our hypothesis that long-term dietary nitrite/nitrate deficiency would induce the metabolic syndrome in mice. To this end, we prepared a low-nitrite/nitrate diet (LND) consisting of an amino acid-based low-nitrite/nitrate chow, in which the contents of L-arginine, fat, carbohydrates, protein and energy were identical with a regular chow, and potable ultrapure water. Nitrite and nitrate were undetectable in both the chow and the water. Three months of the LND did not affect food or water intake in wild-type C57BL/6J mice compared with a regular diet (RD). However, in comparison with the RD, 3 months of the LND significantly elicited visceral adiposity, dyslipidaemia and glucose intolerance. Eighteen months of the LND significantly provoked increased body weight, hypertension, insulin resistance and impaired endothelium-dependent relaxations to acetylcholine, while 22 months of the LND significantly led to death mainly due to cardiovascular disease, including acute myocardial infarction. These abnormalities were reversed by simultaneous treatment with sodium nitrate, and were significantly associated with endothelial NOS downregulation, adiponectin insufficiency and dysbiosis of the gut microbiota. These results provide the first evidence that long-term dietary nitrite/nitrate deficiency gives rise to the metabolic syndrome, endothelial dysfunction and cardiovascular death in mice, indicating a novel pathogenetic role of the exogenous NO production system in the metabolic syndrome and its vascular complications.

  1. Plasma nitrate and nitrite are increased by a high nitrate supplement, but not by high nitrate foods in older adults

    Science.gov (United States)

    Miller, Gary D.; Marsh, Anthony P.; Dove, Robin W.; Beavers, Daniel; Presley, Tennille; Helms, Christine; Bechtold, Erika; King, S. Bruce; Kim-Shapiro, Daniel

    2012-01-01

    Little is known about the effect of dietary nitrate on the nitrate/nitrite/NO (nitric oxide) cycle in older adults. We examined the effect of a 3-day control diet vs. high nitrate diet, with and without a high nitrate supplement (beetroot juice), on plasma nitrate and nitrite kinetics, and blood pressure using a randomized four period cross-over controlled design. We hypothesized that the high nitrate diet would show higher levels of plasma nitrate/nitrite and blood pressure compared to the control diet, which would be potentiated by the supplement. Participants were eight normotensive older men and women (5 female, 3 male, 72.5±4.7 yrs) with no overt disease or medications that affect NO metabolism. Plasma nitrate and nitrite levels and blood pressure were measured prior to and hourly for 3 hours after each meal. The mean daily changes in plasma nitrate and nitrite were significantly different from baseline for both control diet+supplement (pnitrate and nitrite, respectively) and high nitrate diet+supplement (p=0.001 and 0.002), but not for control diet (p=0.713 and 0.741) or high nitrate diet (p=0.852 and 0.500). Blood pressure decreased from the morning baseline measure to the three 2 hr post-meal follow-up time-points for all treatments, but there was no main effect for treatment. In healthy older adults, a high nitrate supplement consumed at breakfast elevated plasma nitrate and nitrite levels throughout the day. This observation may have practical utility for the timing of intake of a nitrate supplement with physical activity for older adults with vascular dysfunction. PMID:22464802

  2. Effect of sodium nitrite on ischaemia and reperfusion-induced arrhythmias in anaesthetized dogs: is protein S-nitrosylation involved?

    Directory of Open Access Journals (Sweden)

    Mária Kovács

    Full Text Available To provide evidence for the protective role of inorganic nitrite against acute ischaemia and reperfusion-induced ventricular arrhythmias in a large animal model.Dogs, anaesthetized with chloralose and urethane, were administered intravenously with sodium nitrite (0.2 µmol kg(-1 min(-1 in two protocols. In protocol 1 nitrite was infused 10 min prior to and during a 25 min occlusion of the left anterior descending (LAD coronary artery (NaNO2-PO; n = 14, whereas in protocol 2 the infusion was started 10 min prior to reperfusion of the occluded vessel (NaNO2-PR; n = 12. Control dogs (n = 15 were infused with saline and subjected to the same period of ischaemia and reperfusion. Severities of ischaemia and ventricular arrhythmias, as well as changes in plasma nitrate/nitrite (NOx levels in the coronary sinus blood, were assessed throughout the experiment. Myocardial superoxide and nitrotyrosine (NT levels were determined during reperfusion. Changes in protein S-nitrosylation (SNO and S-glutathionylation were also examined.Compared with controls, sodium nitrite administered either pre-occlusion or pre-reperfusion markedly suppressed the number and severity of ventricular arrhythmias during occlusion and increased survival (0% vs. 50 and 92% upon reperfusion. There were also significant decreases in superoxide and NT levels in the nitrite treated dogs. Compared with controls, increased SNO was found only in NaNO2-PR dogs, whereas S-glutathionylation occurred primarily in NaNO2-PO dogs.Intravenous infusion of nitrite profoundly reduced the severity of ventricular arrhythmias resulting from acute ischaemia and reperfusion in anaesthetized dogs. This effect, among several others, may result from an NO-mediated reduction in oxidative stress, perhaps through protein SNO and/or S-glutathionylation.

  3. Why Calcium? How Calcium Became the Best Communicator*

    Science.gov (United States)

    Carafoli, Ernesto; Krebs, Joachim

    2016-01-01

    Calcium carries messages to virtually all important functions of cells. Although it was already active in unicellular organisms, its role became universally important after the transition to multicellular life. In this Minireview, we explore how calcium ended up in this privileged position. Most likely its unique coordination chemistry was a decisive factor as it makes its binding by complex molecules particularly easy even in the presence of large excesses of other cations, e.g. magnesium. Its free concentration within cells can thus be maintained at the very low levels demanded by the signaling function. A large cadre of proteins has evolved to bind or transport calcium. They all contribute to buffer it within cells, but a number of them also decode its message for the benefit of the target. The most important of these “calcium sensors” are the EF-hand proteins. Calcium is an ambivalent messenger. Although essential to the correct functioning of cell processes, if not carefully controlled spatially and temporally within cells, it generates variously severe cell dysfunctions, and even cell death. PMID:27462077

  4. Why Calcium? How Calcium Became the Best Communicator.

    Science.gov (United States)

    Carafoli, Ernesto; Krebs, Joachim

    2016-09-30

    Calcium carries messages to virtually all important functions of cells. Although it was already active in unicellular organisms, its role became universally important after the transition to multicellular life. In this Minireview, we explore how calcium ended up in this privileged position. Most likely its unique coordination chemistry was a decisive factor as it makes its binding by complex molecules particularly easy even in the presence of large excesses of other cations, e.g. magnesium. Its free concentration within cells can thus be maintained at the very low levels demanded by the signaling function. A large cadre of proteins has evolved to bind or transport calcium. They all contribute to buffer it within cells, but a number of them also decode its message for the benefit of the target. The most important of these "calcium sensors" are the EF-hand proteins. Calcium is an ambivalent messenger. Although essential to the correct functioning of cell processes, if not carefully controlled spatially and temporally within cells, it generates variously severe cell dysfunctions, and even cell death. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. A comparative study of nitrite reduction by synthetic and biogenic Fe(II-III) hydroxysalts green rusts: Evidence for hydroxyl-nitrite green rust formation as an intermediate reaction product.

    Science.gov (United States)

    Ona-Nguema, G.; Guerbois, D.; Morin, G.; Zhang, Y.; Noel, V.; Brest, J.

    2013-12-01

    The occurrence of high nitrite concentrations as a result of anthropogenic activities is an important water quality concern as it is highly toxic to human and fauna, and it is used as a nitrogen source for the assimilation process. The toxicity of nitrite is related to its transformation into carcinogenic N-nitroso compounds, which are suspected to be responsible for some gastric cancers, and to its ability to convert the hemoglobin to methaemoglobin what is then unable to fix oxygen and to transport it to the tissues, involving hypoxia and the blue-baby syndrome [1]. To reduce the adverse effect of nitrite on human health and on macroalgal blooms, any process enhancing the transformation of nitrite ions to nitrogen gas is of interest for the remediation of natural environments. To achieve this purpose the use of processes involving Fe(II)-containing minerals could be considered as one of the best options. Green-rusts are mixed Fe(II-III) layered double hydroxides commonly found in anoxic zones of natural environments such as sediments and hydromorphic soils. In such anoxic environments, green rust minerals play an important role in the biogeochemical redox cycling of iron and nitrogen, and can affect the speciation and mobility of many organic and inorganic contaminants. The present study investigates the reduction of nitrite by two synthetic and two biogenic green rusts. On the one hand, Fe(II-III) hydroxychloride and Fe(II-III) hydroxycarbonate green rusts were used as synthetic interlayer forms of GR, which are referred to as ';syn-GR(CO3)' and ';syn-GR(Cl)', respectively. On the other hand, the study was performed with biogenic Fe(II-III) hydroxycarbonate green rusts obtained from the bioreduction of two ferric precursors, either Fe(III)-oxyhydroxycarbonate or lepidocrocite; these biogenic green rusts are referred to as ';bio-GR(CO3)F' and ';bio-GR(CO3)L', respectively. For synthetic green rusts, results showed that the oxidation of both syn-GR(CO3) and syn

  6. Testosterone increases urinary calcium excretion and inhibits expression of renal calcium transport proteins.

    NARCIS (Netherlands)

    Hsu, Y.J.; Dimke, H.; Schoeber, J.P.H.; Hsu, S.C.; Lin, S.H.; Chu, P.; Hoenderop, J.G.J.; Bindels, R.J.M.

    2010-01-01

    Although gender differences in the renal handling of calcium have been reported, the overall contribution of androgens to these differences remains uncertain. We determined here whether testosterone affects active renal calcium reabsorption by regulating calcium transport proteins. Male mice had

  7. Calcium: the molecular basis of calcium action in biology and medicine

    National Research Council Canada - National Science Library

    Pochet, Roland; Donato, Rosario

    2000-01-01

    ... of Calcium Calcium Signalling in Excitable Cells Ca2+ Release in Muscle Cells by N. Macrez and J. Mironneau Calcium Signalling in Neurons Exemplified by Rat Sympathetic Ganglion Cells by S.J. M...

  8. Effect of sodium lactate /sodium diacetate in combination with sodium nitrite on physiochemical, microbial properties and sensory evaluation of cow sausage

    Directory of Open Access Journals (Sweden)

    Habib Sedghi

    2014-11-01

    Full Text Available Sodium nitrite has been always considered as one of the common additives due to its antibacterial effects on Clostridium botulinum and meat products' color, however it produces cancer creating nitrosamine. Recently, organic acids and their salts such as lactates have been employed as antimicrobial compounds. Lactates also improve organileptic properties including color, texture and taste and antioxidant properties. Sodium lactate causes to more reduction of anaerobic spore former bacteria than nitrite, inhibits botulin produced by Clostridium botulinum. Sodium lactate produces a permanent reddish pink color through reduction of deoxymygloboline and producing deoxymyoglobuline. In this study, the decrease of sodium nitrite amount from 120ppm to 15ppm by adding sodium lactate / sodium diacetate led to achieve an acceptable product. The best results revealed through adding 3.0625% of sodium lactate / sodium diacetate in combination with 30ppm sodium nitrite. Results also exhibited more reduction of pathogens' growth than nitrite, enhanced flavor slightly, but unable to produce reddish pink color as produced by nitrite. Results also exhibited that sodium lactate / diacetate cause to retard in microbial growth, reducing chemical change, enhance sensory properties, partially improvement in taste and texture. Although inappropriate color demonstrated sodium lactate / diacetate's inability in red pink color production in 4th sample (contains 15 ppm nitrite, its synergy effect in combination with sodium nitrite on nitroso myoglobuline production has been proven, led to sodium nitrite reduction in sausages.

  9. Stochastic Simulation of Cardiac Ventricular Myocyte Calcium Dynamics and Waves

    OpenAIRE

    Tuan, Hoang-Trong Minh; Williams, George S. B.; Chikando, Aristide C.; Sobie, Eric A.; Lederer, W. Jonathan; Jafri, M. Saleet

    2011-01-01

    A three dimensional model of calcium dynamics in the rat ventricular myocyte was developed to study the mechanism of calcium homeostasis and pathological calcium dynamics during calcium overload. The model contains 20,000 calcium release units (CRUs) each containing 49 ryanodine receptors. The model simulates calcium sparks with a realistic spontaneous calcium spark rate. It suggests that in addition to the calcium spark-based leak, there is an invisible calcium leak caused by the stochastic ...

  10. Lead in calcium supplements (abstract)

    International Nuclear Information System (INIS)

    Rehman, S.; Khalid, N.

    2011-01-01

    Lead present in calcium supplements is of grave concern as some lead levels have been measured up to the extent of regulatory limit set by the United States. Calcium supplements inevitably get contaminated with lead as both are naturally occurring elements. Therefore, it is imperative to indicate its level in these supplements in order to create awareness among consumers. In this study, a sophisticated analytical technique, atomic absorption spectrometry was used to analyze Pb contents in 27 commonly consumed Ca supplements manufactured by different national and multinational companies. The daily intake of lead through these supplements was calculated. Only 10% of the calcium supplements analyzed met the criteria of acceptable Pb levels (1.5 mu g/daily dose) in supplements/consumer products set by the United States. It was also found that Pb intake was highest in chelated calcium supplements 28.5 mu g/daily dose, whereas lowest 0.47 mu g/daily dose through calcium supplements with vitamin D formulation. In order to validate our results from the study conducted, IAEA-certified reference material (animal bone, H-5) was analyzed for its Pb levels. The levels of Pb determined were quite in good agreement with the certified values. (author)

  11. The Reaction of Oxy Hemoglobin with Nitrite: Mechanism, Antioxidant-Modulated Effect, and Implications for Blood Substitute Evaluation

    Directory of Open Access Journals (Sweden)

    Denisa Hathazi

    2018-02-01

    Full Text Available The autocatalytic reaction between nitrite and the oxy form of globins involves free radicals. For myoglobin (Mb, an initial binding of nitrite to the iron-coordinated oxygen molecule was proposed; the resulting ferrous-peroxynitrate species was not detected, but its decay product, the high-valent ferryl form, was demonstrated in stopped-flow experiments. Reported here are the stopped flow spectra recorded upon mixing oxy Hb (native, as well as chemically-derivatized in the form of several candidates of blood substitutes with a supraphysiological concentration of nitrite. The data may be fitted to a simple kinetic model involving a transient met-aqua form, in contrast to the ferryl detected in the case of Mb in a similar reaction sequence. These data are in line with a previous observation of a transient accumulation of ferryl Hb under auto-catalytic conditions at much lower concentrations of nitrite (Grubina, R. et al. J. Biol. Chem. 2007, 282, 12916. The simple model for fitting the stopped-flow data leaves a small part of the absorbance changes unaccounted for, unless a fourth species is invoked displaying features similar to the oxy and tentatively assigned as ferrous-peroxynitrate. Density functional theory (DFT calculations support this latter assignment. The reaction allows for differentiating between the reactivities of various chemically modified hemoglobins, including candidates for blood substitutes. Polymerization of hemoglobin slows the nitrite-induced oxidation, in sharp contrast to oxidative-stress type reactions which are generally accelerated, not inhibited. Sheep hemoglobin is found to be distinctly more resistant to reaction with nitrite compared to bovine Hb, at large nitrite concentrations (stopped-flow experiments directly observing the oxy + nitrite reaction as well as under auto-catalytic conditions. Copolymerization of Hb with bovine serum albumin (BSA using glutaraldehyde leads to a distinct increase of the lag time

  12. Circulating Blood eNOS Contributes to the Regulation of Systemic Blood Pressure and Nitrite Homeostasis

    Science.gov (United States)

    Wood, Katherine C.; Cortese-Krott, Miriam M.; Kovacic, Jason C.; Noguchi, Audrey; Liu, Virginia B.; Wang, Xunde; Raghavachari, Nalini; Boehm, Manfred; Kato, Gregory J.; Kelm, Malte; Gladwin, Mark T.

    2013-01-01

    Objective Mice genetically deficient in endothelial nitric oxide synthase (eNOS−/−) are hypertensive with lower circulating nitrite levels, indicating the importance of constitutively produced nitric oxide (NO•) to blood pressure regulation and vascular homeostasis. While the current paradigm holds that this bioactivity derives specifically from expression of eNOS in endothelium, circulating blood cells also express eNOS protein. A functional red cell eNOS that modulates vascular NO• signaling has been proposed. Approach and Results To test the hypothesis that blood cells contribute to mammalian blood pressure regulation via eNOS-dependent NO• generation, we cross-transplanted WT and eNOS−/− mice, producing chimeras competent or deficient for eNOS expression in circulating blood cells. Surprisingly, we observed a significant contribution of both endothelial and circulating blood cell eNOS to blood pressure and systemic nitrite levels, the latter being a major component of the circulating NO• reservoir. These effects were abolished by the NOS inhibitor L-NAME and repristinated by the NOS substrate L-Arginine, and were independent of platelet or leukocyte depletion. Mouse erythrocytes were also found to carry an eNOS protein and convert 14C-Arginine into 14C-Citrulline in a NOS-dependent fashion. Conclusions These are the first studies to definitively establish a role for a blood borne eNOS, using cross transplant chimera models, that contributes to the regulation of blood pressure and nitrite homeostasis. This work provides evidence suggesting that erythrocyte eNOS may mediate this effect. PMID:23702660

  13. Serial crystallography captures enzyme catalysis in copper nitrite reductase at atomic resolution from one crystal

    Directory of Open Access Journals (Sweden)

    Sam Horrell

    2016-07-01

    Full Text Available Relating individual protein crystal structures to an enzyme mechanism remains a major and challenging goal for structural biology. Serial crystallography using multiple crystals has recently been reported in both synchrotron-radiation and X-ray free-electron laser experiments. In this work, serial crystallography was used to obtain multiple structures serially from one crystal (MSOX to study in crystallo enzyme catalysis. Rapid, shutterless X-ray detector technology on a synchrotron MX beamline was exploited to perform low-dose serial crystallography on a single copper nitrite reductase crystal, which survived long enough for 45 consecutive 100 K X-ray structures to be collected at 1.07–1.62 Å resolution, all sampled from the same crystal volume. This serial crystallography approach revealed the gradual conversion of the substrate bound at the catalytic type 2 Cu centre from nitrite to nitric oxide, following reduction of the type 1 Cu electron-transfer centre by X-ray-generated solvated electrons. Significant, well defined structural rearrangements in the active site are evident in the series as the enzyme moves through its catalytic cycle, namely nitrite reduction, which is a vital step in the global denitrification process. It is proposed that such a serial crystallography approach is widely applicable for studying any redox or electron-driven enzyme reactions from a single protein crystal. It can provide a `catalytic reaction movie' highlighting the structural changes that occur during enzyme catalysis. The anticipated developments in the automation of data analysis and modelling are likely to allow seamless and near-real-time analysis of such data on-site at some of the powerful synchrotron crystallographic beamlines.

  14. Nitrite reduction on a multimetallic porphyrin/polyoxotungstate layer-by-layer modified electrodes

    International Nuclear Information System (INIS)

    García, Macarena; Honores, Jessica; Quezada, Diego; Díaz, Carlos; Dreyse, Paulina; Celis, Freddy; Kubiak, Clifford P.; Canzi, Gabriele; Guzmán, Fernando

    2016-01-01

    Electro and photoelectrochemical reduction of nitrite in aqueous solution was studied using a multielectrocatalysts modified ITO electrode. ITO modification was carried out using the layer-by-layer (LBL) method, where sequential electrostatic assemblies were formed using a μ-(meso-5,10,15,20-tetra(pirydil)porphyrin)tetrakis{bis(bipyridine)chloride ruthenium (II)} [MTRP] n+ , coordinated in its central cavity with Mn(III), Zn(II) or Ni(II) as a cationic layer, and polyoxotungstate [SiW 12 O 40 ] 4− as the anionic layer. Electrochemical measurements and UV–vis spectroscopy were used to monitor the modification process. Optimal results were obtained when three layers were deposited onto the ITO surface and were stable in aqueous solution. The order of the multilayer formation was explored by comparing a modified electrode where [Zn(II)TRP] 4+ was the outermost layer with an electrode where [SiW 12 O 40 ] 4− was the outer layer. Results show that the best performing electrode is one with [SiW 12 O 40 ] 4− as the outer layer. Nitrite reduction on these electrode surfaces was studied in dark conditions and under light irradiation. Potential controlled electrolysis experiments were also performed, finding hydroxylamine, hydrazine and ammonia as the reduction products in dark conditions. Under light irradiation, only hydrazine and ammonia were found and, we observed an increase in the amount of obtained product. In this case, the electrolysis was carried out 150 mV less and half of time than in dark conditions. These results show that the combination of light and potential give rise to an improvement in the electrocatalytic properties of the modified electrodes. Continuous photolysis and IR spectroelectrochemical experiments were carried out to determinate the nature of this phenomena, evidencing the formation of an intermediary species between nitrite and [Mn(III)TRP] 5+.

  15. Electrocatalytic Activity of Carbonized Nanostructured Polyanilines for Oxidation Reactions: Sensing of Nitrite Ions and Ascorbic Acid

    International Nuclear Information System (INIS)

    Micić, Darko; Šljukić, Biljana; Zujovic, Zoran; Travas-Sejdic, Jadranka; Ćirić-Marjanović, Gordana

    2014-01-01

    Highlights: • Carbonized PANIs prepared from various nanostructured PANI precursors • Electroanalytical performances of carbonized PANIs evaluated using voltammetry • Study of carbonized PANIs physico-chemical properties related to electroactivity • The lowest over-potential for NO 2 − oxidation at c-PANI (+0.87 V vs. SCE) • The lowest over-potential for ascorbic acid oxidation at both c-PANI and c-PANI-SSA - Abstract: A comparative study of the electrocatalytic activity of nitrogen-containing carbon nanomaterials, prepared by the carbonization of nanostructured polyaniline (PANI) salts, for the electrooxidation reactions is presented. Nanostructured PANI salts were synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in an aqueous solution in the presence of 5-sulfosalicylic acid (PANI-SSA), 3,5-dinitrosalicylic acid (PANI-DNSA) as well as without added acid (PANI), and subsequently carbonized to c-PANI-SSA, c-PANI-DNSA and c-PANI, respectively. Glassy carbon tip was modified with nanostructured c-PANIs and used for the investigation of sensing of nitrite and ascorbic acid in aqueous solutions as model analytes by linear sweep voltammetry. All three types of the investigated c-PANIs gave excellent response to the nitrite ions and ascorbic acid electrooxidation. The lowest peak potential for nitrite ion oxidation exhibited c-PANI (+0.87 V vs. SCE), and for ascorbic acid oxidation both c-PANI and c-PANI-SSA (ca. + 0.13 V vs. SCE). Electrochemical data were correlated with structural and textural data obtained by Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, elemental and nitrogen sorption analysis

  16. Isomorfic Substitutions of Calcium by Strontium in Calcium Hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, Hilbert

    1962-12-15

    By means of homogeneous precipitation it has been possible to synthesize crystalline solid solutions of calcium strontium hydroxyapatite from aqueous solutions. The lattice constants for the solid solutions were measured in the range Ca{sub 9}Sr(PO{sub 4}){sub 6}(OH){sub 2} - CaSr{sub 9}(PO{sub 4}){sub 6}(OH){sub 2}. The investigations show that the discrimination of strontium against calcium is considerably smaller than reported elsewhere (1). Strontium is preferentially built into the c-axis direction of the apatite lattice.

  17. Spectrophotometric determination of nitrite based on its catalytic effect on the reaction of nuclear fast red and potassium bromate

    Directory of Open Access Journals (Sweden)

    HASSAN ZAVVAR MOUSAVI

    2009-08-01

    Full Text Available A highly selective and sensitive catalytic spectrophotometric method was developed for the determination of nitrite in water samples. The method is based on its catalytic effect on the nuclear fast red–potassium bromate redox reaction in acidic medium. The reaction was followed spectrophotometrically by measuring the change in the absorbance at 518 nm of nuclear fast red 5 min after initiation of the reaction. In this study, the experimental parameters were optimized and the effects of other cations and anions on the determination of nitrite were examined. The calibration graph was linear in the range 2.0–45 µg mL-1 of nitrite. The relative standard deviations for the determination of 15 and 30 µg mL-1 of nitrite were 3.1 and 1.75 %, respectively (n = 8. The detection limit calculated from three times the standard deviation of the blank 3Sb was 0.7 µg mL-1. The method was successfully applied to the determination of nitrite in spiked tap, natural and wastewater samples.

  18. Monitoring of nitrites and nitrates levels in leafy vegetables (spinach and lettuce): a contribution to risk assessment.

    Science.gov (United States)

    Iammarino, Marco; Di Taranto, Aurelia; Cristino, Marianna

    2014-03-15

    Nitrites and nitrates are compounds considered harmful to humans and the major part of the daily intake of nitrates in foodstuffs is related to vegetable consumption. In this work, 150 leafy vegetables samples (75 spinach and 75 lettuce) were analysed in order to assess the levels of nitrites and nitrates. The analyses were carried out by a validated ion chromatography method and the samples with nitrate concentrations higher than legal limits and/or with quantifiable concentrations of nitrites were confirmed by an alternative ion chromatography method. Nitrate levels higher than legal limits were detected both in spinach (four samples) and in lettuce (five samples). Nitrite residues were registered both at low concentrations--lower than 28.5 mg kg⁻¹ (12 spinach samples)--and at high concentrations, up to 197.5 mg kg⁻¹ (three spinach and one lettuce sample). Considering the non-negligible percentage of 'not-compliant' samples for nitrates (6.0%), control is needed. Moreover, it is possible to suggest the introduction in the Communities Regulations of a 'maximum admissible level' for nitrites in leafy vegetables. © 2013 Society of Chemical Industry.

  19. Increase in nitrite content and functionality of ethanolic extracts of Perilla frutescens following treatment with atmospheric pressure plasma.

    Science.gov (United States)

    Jung, Samooel; Lee, Chul Woo; Lee, Juri; Yong, Hae In; Yum, Su Jin; Jeong, Hee Gon; Jo, Cheorun

    2017-12-15

    This study investigated the effect of atmospheric pressure plasma (APP) treatment on nitrite content and functionality of plant extracts. Ethanolic extracts of Perilla frutescens (EEP) were prepared and treated with APP for 60min. Nitrite content increased from 0 to 45.8mg/l in EEP after APP treatment for 60min. Antimicrobial activity of EEP against Clostridium perfringens and Salmonella Typhimurium was increased by APP with no influence on antioxidative activity (p<0.05). Lyophilized EEP (LEEP) treated with APP for 60min contained 3.74mg/g nitrite. The control (LEEP without APP) contained no nitrite. The minimum inhibitory concentration (MIC) of LEEP for C. perfringens was 200µg/ml. The control did not inhibit C. perfringens growth between 25 and 1000µg/ml. MICs of LEEP and the control against S. Typhimurium were 25 and 50µg/ml, respectively. New nitrite sources with increased antimicrobial activity can be produced from natural plants by APP treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Does nitrite and nitrate levels in drinking water impact the health of people in Dakahlia governorate, Egypt?

    Science.gov (United States)

    Mortada, Wael I; Shokeir, Ahmed A

    2018-05-07

    A total of 1291 drinking water samples were examined for nitrite and nitrate during 6 months from December, 2015 to May, 2016 at 17 cities of Dakahlia governorate (Nile Delta, north of Egypt), and the results were utilized for assessment of health risk of the exposure from drinking water by calculating average daily intake (ADI), hazard quotient (HQ), and the hazard index (HI). The nitrite and nitrate in drinking water had a concentration range of 0.030-0.113 and 2.41-8.70 mg L -1 , with mean values of 0.059 ± 0.014 and 5.25 ± 1.61 mg L -1 , respectively. Nitrite and nitrate levels in rural areas and ground water samples were significantly higher than that in the urban ones. None of the analyzed samples exceeded WHO guideline values that set out to prevent methemoglobinemia. The values of HQ and HI for all age groups do not exceed unity indicating a low risk of methaemoglobinaemia for the population in this area. Results of the present study indicate that there is no health risk of residents from nitrite and nitrate through drinking water in the studied area. However, the other sources of exposure to nitrite and nitrate should be investigated in further studies.