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Sample records for calcium nitrite

  1. Effect of calcium nitrite on the properties of concrete used in prestressed piles and beams.

    Science.gov (United States)

    1992-01-01

    This study evaluates the concretes in steam-cured prestressed piles and beams containing calcium nitrite as protection against chloride-induced corrosion of the steel strands and assesses their field performance over a 3-year period. Concretes contai...

  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 water binding by myofibrils. The depressed muscle fiber swelling responding to added calcium as evidenced by phase contrast microscopy substantiated, to a certain extent, the deleterious effect of calcium, suggesting that hardness of curing water can significantly affect the quality of cured 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. Diisopropylammonium nitrite

    Directory of Open Access Journals (Sweden)

    Ying-Chun Wang

    2012-04-01

    Full Text Available In the title molecular salt, C6H16N+·NO2−, the cation forms two N—H...O hydrogen bonds to nearby nitrite anions which link the ionic units into chains propagating along the b-axis direction.

  4. Intercomparison 9610, pH, conductivity, alkalinity, nitrate + nitrite, chloride, sulfate, calcium, magnesium, sodium, potassium, total aluminium, reactive and non-labile aluminium, dissolved organic carbon, and chemical oxygen demand (ICP Waters report)

    OpenAIRE

    Hovind, H.

    1996-01-01

    36 laboratories in 21 countries participated in intercomparison 9610. Two sample sets, one for the major ions and one for organic matter and aluminium fractions, were used. Based on the general target accuracy of + 20%, 70% of the results were acceptable. More than 80% of the result pairs were acceptable for conductivity, nitrate+nitrite, calcium, sodium and dissolved organic carbon. For pH only 55% of the result pairs were acceptable in relation to the extended target accuracy of + 0.2 units...

  5. Protective effect of the calcium antagonist nimodipine on discrimination learning deficits and impaired retention behavior caused by prenatal nitrite exposure in rats

    NARCIS (Netherlands)

    Nyakas, Csaba; Markel, Éva; Bohus, Béla; Schuurman, Teun; Luiten, Paulus

    1990-01-01

    Discrimination learning behavior and retention of a passive avoidance response were studied in male adult offspring of gestating rats exposed to drinking water containing 2 g/l sodium nitrite, throughout the second half of pregnancy. Both in an auditory and visual discrimination learning paradigm

  6. Calcium

    Science.gov (United States)

    ... Turn to calcium-fortified (or "calcium-set") tofu, soy milk, tempeh, soy yogurt, and cooked soybeans (edamame). Calcium-fortified foods. Look for calcium-fortified orange juice, soy or rice milk, breads, and cereal. Beans. You can get decent ...

  7. Calcium

    Science.gov (United States)

    ... and blood vessels contract and expand, to secrete hormones and enzymes and to send messages through the nervous system. It is important to get plenty of calcium in the foods you eat. Foods rich in calcium include Dairy products such as milk, cheese, and yogurt Leafy, green vegetables Fish with ...

  8. 21 CFR 181.34 - Sodium nitrite and potassium nitrite.

    Science.gov (United States)

    2010-04-01

    ... fixatives and preservative agents, with or without sodium or potassium nitrate, in the curing of red meat... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium nitrite and potassium nitrite. 181.34...-Sanctioned Food Ingredients § 181.34 Sodium nitrite and potassium nitrite. Sodium nitrite and potassium...

  9. Calcium

    Science.gov (United States)

    ... from dietary supplements are linked to a greater risk of kidney stones, especially among older adults. But calcium from foods does not appear to cause kidney stones. For most people, other factors (such as not drinking enough fluids) probably have ...

  10. Intercomparison 9812. pH, conductivity, alkalinity, nitrate + nitrite, chloride, sulfate, calcium, magnesium, sodium, potassium, total aluminium, reactive and non-labile aluminium, dissolved organic carbon, and chemical oxygen demand (ICP Waters report 49/1998)

    OpenAIRE

    Hovind, H.

    1998-01-01

    43 laboratories in 20 countries participated in intercomparison 9812. One sample set for the determination of major ions, organic matter and aluminium fractions, were used. Based on the general target accuracy of * 20 %, 74 % of the results were acceptable. More than 80 % of the result pairs were acceptable for conductivity, nitrate + nitrite, sulfate, sodium, and dissolved organic carbon. For pH only 55 % of the result pairs were acceptable in relation to the extended target accuracy of * 0....

  11. Comparative Behaviour of Nitrite and Nitrate for the Protection of Rebar Corrosion

    Science.gov (United States)

    Ahmad, Altaf; Kumar, Anil

    2017-10-01

    Corrosion of rebar steel due to environmental causes has been studied through various approaches, and among the protection techniques use of inhibitors has gained encouragement. Nitrites and nitrates of sodium have gained sufficient scientific coverage. Recently, nitrites and nitrates of calcium have been verified in some studies, which, however, needs further experimentation through different angles. Simple polarization technique has been utilized in the present study to compare inhibitive efficiency of these salts of sodium and calcium, which indicate that calcium salts are more efficient.

  12. Nitrite toxicity of Litopenaeus vannamei in water containing low concentrations of sea salt or mixed salts

    Science.gov (United States)

    Sowers, A.; Young, S.P.; Isely, J.J.; Browdy, C.L.; Tomasso, J.R.

    2004-01-01

    The uptake, depuration and toxicity of environmental nitrite was characterized in Litopenaeus vannamei exposed in water containing low concentrations of artificial sea salt or mixed salts. In 2 g/L artificial sea salts, nitrite was concentrated in the hemolymph in a dose-dependent and rapid manner (steady-state in about 2 d). When exposed to nitrite in 2 g/L artificial sea salts for 4 d and then moved to a similar environment without added nitrite, complete depuration occurred within a day. Increasing salinity up to 10 g/L decreased uptake of environmental nitrite. Nitrite uptake in environments containing 2 g/L mixed salts (combination of sodium, potassium, calcium and magnesium chlorides) was similar to or lower than rates in 2 g/L artificial sea salt. Toxicity was inversely related to total dissolved salt and chloride concentrations and was highest in 2 g/L artificial sea salt (96-h medial lethal concentration = 8.4 mg/L nitrite-N). Animals that molted during the experiments did not appear to be more susceptible to nitrite than animals that did not molt. The shallow slope of the curve describing the relationship between toxicity and salinity suggests that management of nitrite toxicity in low-salinity shrimp ponds by addition of more salts may not be practical. ?? Copyright by the World Aquaculture Society 2004.

  13. Intercomparison 9711. pH, conductivity, alkalinity, nitrate + nitrite, chloride, sulfate, calcium, magnesium, sodium, potassium, total aluminium, reactive and non-labile aluminium, dissolved organic carbon, and chemical oxygen demand (ICP Waters report)

    OpenAIRE

    Hovind, H.

    1997-01-01

    47 laboratories in 22 countries participated in intercomparison 9711. One sample set for the determination of major ions, organic matter and aluminium fractions, were used. Based on the general target accuracy of + 20%, 78% of the results were acceptable. More than 80% of the result pairs were acceptable for chloride, sulfate, calcium, mangnesium, sodium, dissolved organic carbon and chemical oxygen demand. For pH only 43% of the result pairs were acceptable in relation to the extended target...

  14. ADVANCED TECHNOLOGY WASTEWATER TREATMENT OF NITRITE IONS

    Directory of Open Access Journals (Sweden)

    E.G. Morozov

    2012-06-01

    Full Text Available The main reason for high concentration of nitrite ions in water is the existence of sources of industrial and agricultural pollution. Contamination of drinking water, juices, wine and other liquids of nitrite ions as a result of improper use of nitrogen fertilizers has an adverse effect on living organism, because under the influence of enzymes nitrite ions in living organisms form high carcinogenic nitrosamines, and the interaction of nitrite ions from blood hemoglobin causes such toxicity that leads to disease cyanosis [1]. Therefore removal of nitrite ions from water has received increased attention. The paper discusses an innovative wastewater treatment technology from the nitrite ion with hypochlorite produced during electrolysis.

  15. Pseudoazurin-nitrite reductase interactions.

    Science.gov (United States)

    Impagliazzo, Antonietta; Krippahl, Ludwig; Ubbink, Marcellus

    2005-09-01

    The nitrite reductase-binding site on pseudoazurin has been determined by using NMR chemical-shift perturbations. It comprises residues in the hydrophobic patch surrounding the exposed copper ligand His81 as well as several positively charged residues. The binding site is similar for both redox states of pseudoazurin, despite differences in the binding mode. The results suggest that pseudoazurin binds in a well-defined orientation. Docking simulations provide a putative structure of the complex with a binding site on nitrite reductase that has several hydrophobic and polar residues as well as a ridge of negatively charged side chains and a copper-to-copper distance of 14 A.

  16. A novel marine nitrite-oxidizing

    NARCIS (Netherlands)

    Haaijer, S.C.M.; Ji, K.; van Niftrik, L.; Hoischen, A.; Speth, D.R.; Jetten, M.S.M.; Sinninghe Damsté, J.S.; Op den Camp, H.J.M.

    2013-01-01

    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

  17. 21 CFR 573.700 - Sodium nitrite.

    Science.gov (United States)

    2010-04-01

    ... Listing § 573.700 Sodium nitrite. Sodium nitrite may be safely used in canned pet food containing meat and... 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...

  18. Nitric oxide formation from nitrite in zebrafish

    DEFF Research Database (Denmark)

    Jensen, Frank Bo

    2007-01-01

    Nitrite is a potential nitric oxide (NO) donor and may have important biological functions at low concentrations. The present study tests the hypothesis that nitrite accumulation across the gills in fish will cause a massive NO production from nitrite. Zebrafish were exposed to three different...

  19. 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.

  20. 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..

  1. 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.

  2. Nitrite in hamburgers in Arak, Iran.

    Science.gov (United States)

    Rezaei, Mohammad; Shariatifar, Nabi; Jahed Khaniki, Gholamreza; Javadzadeh, Morteza

    2013-01-01

    Nitrite and nitrate are used as additives in meat products to provide colour, taste and protection against micro-organisms, but excessive use of these substances can be toxic and can cause carcinogenesis in man. Natural and organic foods are not permitted to use chemical preservatives, the traditional curing agents used for cured meats, and so nitrate and/or nitrite cannot be added to hamburgers. This study aimed to measure nitrite in hamburgers sold in Arak city, in the centre of Iran, in 2011. For this purpose, 105 samples were randomly selected and analysed according to Official AOAC Method 973. The residual nitrite in the samples was 30-100 mg/kg (p < 0.001). In 85.7% of the samples, presence of nitrite was demonstrated, which suggests unfavourable production conditions and poor sodium nitrite standards at hamburger factories.

  3. Controlled-potential iodometric titration of nitrite. Application to the determination of nitrite in meat products.

    Science.gov (United States)

    Karlsson, R; Torstensson, L G

    1974-09-01

    A controlled-potential coulometric method using iodine as an intermediate has been devised for the determination of nitrite. Nitrite is reduced by iodide and the iodine formed is then reduced coulometrically. The reduction of nitrite in the pH range 0-6 has been studied and the optimum conditions for an accurate determination are stated. The time of analysis for a determination in the range 0.005-5 mg of nitrite is about 2-5 min and the error +/- 0.1%. The method is applied to the determination of nitrite in some meat products.

  4. SPECTROPHOTOMETRIC DETERMINATION OF NITRITE BY ITS ...

    African Journals Online (AJOL)

    Preferred Customer

    KEY WORDS: Nitrite, Catalytic effect, Congo red, Spectrophotometry, Drinking water. INTRODUCTION ... such as high sensitivity, low detection limits, good selectivity, rapid analysis and inexpensive instrumentation. ... Determination of nitrite by its catalytic effect on oxidation of congo red with bromate. Bull. Chem. Soc.

  5. Radiation preservation of low nitrite bacon

    Science.gov (United States)

    Singh, Harwant

    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 microorganisms, 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°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° 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.

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

    National Research Council Canada - National Science Library

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

    2015-01-01

    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...

  7. New composite nitrite-free and low-nitrite meat-curing systems using natural colorants.

    Science.gov (United States)

    Eskandari, Mohammad H; Hosseinpour, Sara; Mesbahi, Gholamreza; Shekarforoush, Shahram

    2013-09-01

    Nitrite-free and low-nitrite meat-curing systems were developed to eliminate or reduce nitrite in frankfurter-type sausages. Different composite meat-curing mixtures were formulated using cochineal and paprika as natural colorants, sodium hypophosphite (SHP) as antimicrobial agent, butylated hydroxyanisole (BHA) as antioxidant and sodium nitrite. The treatment, which contained 0.015% cochineal, most closely resembled the 120 ppm NaNO2 in its ability to create cured-meat color. BHA was found to be a strong antioxidant at the 30 ppm level in cooked sausages during refrigerated storage for 5 weeks. All treatments containing 40 ppm sodium nitrite were successful in replicating sensory attributes of frankfurter samples. Our findings support the use of SHP as possible antibotulinal agent in nitrite-free meat-curing systems.

  8. Community Analysis of Ammonia and Nitrite Oxidizers during Start-Up of Nitritation Reactors

    OpenAIRE

    Egli, Konrad; Langer, Christian; Siegrist, Hans-Ruedi; Zehnder, Alexander J. B.; Wagner, Michael; van der Meer, Jan Roelof

    2003-01-01

    Partial nitrification of ammonium to nitrite under oxic conditions (nitritation) is a critical process for the effective use of alternative nitrogen removal technologies from wastewater. Here we investigated the conditions which promote establishment of a suitable microbial community for performing nitritation when starting from regular sewage sludge. Reactors were operated in duplicate under different conditions (pH, temperature, and dilution rate) and were fed with 50 mM ammonium either as ...

  9. Nitrate, Nitrite, and nitroso compounds in foods

    Energy Technology Data Exchange (ETDEWEB)

    Hotchkiss, J.H.; Cassens, R.G.

    1987-04-01

    The concern that human foods might contain nitroso compounds stems from the discovery in the early 1960s that domestic animals fed fish meal preserved with high levels of sodium nitrite were dying of liver failure. It has been known for many years that nitrite can combine with amines to form N-nitrosamines. N-nitrosodimethylamine was determined to be the cause of the liver failure. The nitrosamine resulted from the reaction between dimethylamine contained in the fish and the added nitrite. Because nitrite is an important and widely used human food additive, particularly in the curing of meats, poultry, and fish, research was undertaken by several groups around the world to investigate the occurrence of these compounds in human foods.

  10. Calcium - urine

    Science.gov (United States)

    Urinary Ca+2; Kidney stones - calcium in urine; Renal calculi - calcium in your urine; Parathyroid - calcium in urine ... Urine calcium level can help your provider: Decide on the best treatment for the most common type of kidney ...

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

    Directory of Open Access Journals (Sweden)

    Célio Damacena-Angelis

    2017-08-01

    Full Text Available 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 (15N-nitrite by aortic rings using ultra-performance liquid chromatography tandem mass-spectrometry (UPLC-MS/MS. Nitrate exerted no effect on aortic accumulation of 15N-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

  12. 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.

  13. 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 ...

  14. Chemically modified field effect transistors with nitrite or fluoride selectivity

    NARCIS (Netherlands)

    Antonisse, M.M.G.; Ruel, Bianca H.M.; Engbersen, Johannes F.J.; Reinhoudt, David

    1998-01-01

    Polysiloxanes with different types of polar substituents are excellent membrane materials for nitrite and fluoride selective chemically modified field effect transistors (CHEMFETs). Nitrite selectivity has been introduced by incorporation of a cobalt porphyrin into the membrane; fluoride selectivity

  15. Calcium Carbonate

    Science.gov (United States)

    Calcium carbonate is a dietary supplement used when the amount of calcium taken in the diet is not ... for healthy bones, muscles, nervous system, and heart. Calcium carbonate also is used as an antacid to relieve ...

  16. 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 ...

  17. 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...

  18. Electrochemical removal of nitrite in simulated aquaculture wastewater

    African Journals Online (AJOL)

    use

    2011-11-21

    Nov 21, 2011 ... literature on aquaculture wastewater (AW), studies is more replete as AW is contaminated with toxic sub- stances like nitrite and nitrate (Lin and Wu, 1996;. Virkutyte and Jegatheesan, 2009; Virkutyte et al., 2010). The hazardous and toxic nature of nitrite is a major concern. Nitrite results in the wastewater ...

  19. Seasonal Distribution of Nitrate and Nitrite Levels in Eleme Abattoir ...

    African Journals Online (AJOL)

    MICHAEL

    should be periodic evaluation of nitrate and nitrite levels in the area. @ JASEM .... Table 6: Comparison of the levels of Nitrate and Nitrite in Surface and Groundwater in the Dry Season with WHO (1988) Standards. Unaffected ... Table 7: Calculated Ratios of Nitrate and Nitrite to WHO (1988) Guideline values. Season Ratios ...

  20. 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...

  1. 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 regulatio...

  2. 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.

  3. Inhibition kinetics of nitritation and half-nitritation of old landfill leachate in a membrane bioreactor.

    Science.gov (United States)

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

    2017-04-01

    Nitritation can be used as a pretreatment for anaerobic ammonia oxidation (anammox). Various control strategies for nitritation and half-nitritation of old landfill leachate in a membrane bioreactor were investigated in this study and the inhibition kinetics of substrate, product and old landfill leachate on nitritation were analyzed via batch tests. The results demonstrated that old landfill leachate nitritation in the membrane bioreactor can be achieved by adjusting the influent loading and dissolved oxygen (DO). From days 105-126 of the observation period, the average effluent concentration was 871.3 mg/L and the accumulation rate of [Formula: see text] was 97.2%. Half-nitritation was realized quickly by adjusting hydraulic retention time and DO. A low-DO control strategy appeared to best facilitate long-term and stable operation. Nitritation inhibition kinetic experiments showed that the inhibition of old landfill leachate was stronger than that of the substrate [Formula: see text] or product [Formula: see text] . The ammonia oxidation rate dropped by 22.2% when the concentration of old landfill leachate (calculated in chemical oxygen demand) was 1600.2 mg/L; further, when only free ammonia or free nitrous acid were used as a single inhibition factor, the ammonia oxidation rate dropped by 4.7-6.5% or 14.5-15.9%, respectively. Haldane, Aiba, and a revised inhibition kinetic model were adopted to separately fit the experimental data. The R 2 correlation coefficient values for these three models were 0.982, 0.996, and 0.992, respectively. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  4. 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

  5. Nitrite in feed: from animal health to human health.

    Science.gov (United States)

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

    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 3.3mg/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

  6. Nitrite-free Asian hot dog sausages reformulated with nitrite replacers.

    Science.gov (United States)

    Ruiz-Capillas, C; Tahmouzi, S; Triki, M; Rodríguez-Salas, L; Jiménez-Colmenero, F; Herrero, A M

    2015-07-01

    This research deals with the application of a global strategy designed to produce a nitrite-free Asian hot dog. Different ingredients such as annatto, cochineal, orange dietary fibre, vitamins E and C, lactate and celery were combined in order to study the appearance (colour), lipid oxidation stability and microbial stability of the nitrite-free formulations. The control sample contained much more (P annatto (RA) had the lowest a* values. Lipid oxidation levels were similar irrespective of formulation. The hot dog reformulated with cochineal (RC) scored higher for overall acceptability than RA, mainly due to its colour.

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

    DEFF Research Database (Denmark)

    Dalsgaard, Thomas; Simonsen, Ulf; Fago, Angela

    2007-01-01

    The reduction of circulating nitrite to nitric oxide (NO) has emerged as an important physiological reaction aimed to increase vasodilation during tissue hypoxia. Although hemoglobin, xanthine oxidase, endothelial NO synthase, and the bc(1) complex of the mitochondria are known to reduce nitrite...... target for vasoactive NO), and known nitrite reductase activities under hypoxia. Vasodilation followed overall first-order dependency on nitrite concentration and, at low oxygenation and norepinephrine levels, was induced by low-nitrite concentrations, comparable to those found in vivo. The vasoactive...... effect of nitrite during hypoxia was abolished on inhibition of soluble guanylate cyclase and was unaffected by removal of the endothelium or by inhibition of xanthine oxidase and of the mitochondrial bc(1) complex. In the presence of hemoglobin and inositol hexaphosphate (which increases the fraction...

  8. Comparative analysis of nitrite uptake and hemoglobin-nitrite reactions in erythrocytes: sorting out uptake mechanisms and oxygenation dependencies

    DEFF Research Database (Denmark)

    Jensen, Frank Bo; Rohde, Sabina

    2010-01-01

    (hagfish and lamprey) anion exchanger-1 (AE1) in the membrane, with the aim to unravel the mechanisms and oxygenation dependencies of nitrite transport. Added nitrite rapidly diffused into the RBCs until equilibrium. The distribution ratio of nitrite across the membrane agreed with that expected from HNO2...... diffusion and AE1-mediated facilitated NO2- diffusion. Participation of HNO2 diffusion was emphasized by rapid transmembrane nitrite equilibration also in the natural AE1 knockouts. Following the equilibration, nitrite was consumed by reacting with Hb, which created a continued inward diffusion controlled....... We propose a model for RBC nitrite uptake that involves both HNO2 diffusion and AE1-mediated transport and which explains both the present and previous (sometimes puzzling) results....

  9. Hypoxia tolerance, nitric oxide, and nitrite

    DEFF Research Database (Denmark)

    Fago, Angela; Jensen, Frank Bo

    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...... of NO and nitrite signaling in the adaptive response to hypoxia in vertebrate animals.......Among vertebrates able to tolerate periods of oxygen deprivation, the painted and red-eared slider turtles (Chrysemys picta and Trachemys scripta) and the crucian carp (Carassius carassius) are the most extreme and can survive even months of total lack of oxygen during winter. The key to hypoxia...

  10. The nitrite oxidizing system of Nitrobacter winogradskyi.

    Science.gov (United States)

    Yamanaka, T; Fukumori, Y

    1988-12-01

    Cytochrome components which participate in the oxidation of nitrite in Nitrobacter winogradskyi have been highly purified and their properties studied in detail. Cytochrome a1c1 is an iron-sulphur molybdoenzyme which has haems a and c and acts as a nitrite-cytochrome c oxidoreductase. Cytochrome c-550 is homologous to eukaryotic cytochrome c and acts as the electron mediator between cytochrome a1c1 and aa3-type cytochrome c oxidase. The oxidase is composed of two kinds of subunits, has two molecules of haem a and two atoms of copper in the molecule, and oxidizes actively eukaryotic ferrocytochrome c as well as its own ferrocytochrome c-550. Further, a flavoenzyme has been obtained which has transhydrogenase activity and catalyses reduction of NADP+ with benzylviologen radical. This enzyme may be responsible for production of NADPH in N. winogradskyi. The electron transfer against redox potential from NO2- to cytochrome c could be pushed through prompt removal by cytochrome aa3 of H+ formed by the dehydrogenation of NO2- + H2O. As cytochrome c in anaerobically kept cell-free extracts is rapidly reduced on addition of NO2-, a membrane potential does not seem necessary for the reduction of cytochrome c by cytochrome a1c1 with NO2- in vivo.

  11. Modifying a known gelator scaffold for nitrite detection.

    Science.gov (United States)

    Zurcher, Danielle M; Adhia, Yash J; Romero, Julián Díaz; McNeil, Anne J

    2014-07-25

    The process of selecting and modifying a known gelator scaffold to develop a new nitrite-based sensor is described. Five new azo-sulfonate gelators were discovered and characterized. The most promising scaffold exhibits a stable diazonium intermediate, proceeds in a high yield, and gels nitrite-spiked tap, river, and pond water.

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

    African Journals Online (AJOL)

    Amani Cherif-Sayadi

    2017-03-30

    Mar 30, 2017 ... 2 h. Control livers were perfused without cold storage. Results: Nitrite effectively protected the rat liver grafts from the onset of cold I/R injury. L-NAME treatment did not abolish the beneficial effects of nitrite. Liver damage, protein oxidation .... phosphatase (PAL) are associated with hepatocellular damage ...

  13. Nitrate and nitrite in biology, nutrition and therapeutics

    NARCIS (Netherlands)

    Lundberg, J.O.; van Faassen, E.E.H.|info:eu-repo/dai/nl/071100938; 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.

  14. Nitrite as regulator of hypoxic signaling in mammalian physiology

    NARCIS (Netherlands)

    van Faassen, E.E.H.|info:eu-repo/dai/nl/071100938; Bahrami, S.; Feelisch, M.; Hogg, N.; Kelm, M.

    2009-01-01

    In this review we consider the effects of endogenous and pharmacological levels of nitrite under conditions of hypoxia. In humans, the nitrite anion has long been considered as metastable intermediate in the oxidation of nitric oxide radicals to the stable metabolite nitrate. This oxidation cascade

  15. Electrochemical removal of nitrite in simulated aquaculture wastewater

    African Journals Online (AJOL)

    Electrochemical removal of nitrite at a concentration of 10 mg l-1 from synthetic aquaculture wastewater was investigated in this study using a batch reactor. The effects of important operating parameters such as electrode material and applied current density were studied. The highest nitrite removal is achieved with nickel ...

  16. Unraveling the origin of the nitrite-mediated hypoxic vasodilation

    DEFF Research Database (Denmark)

    Fago, Angela; Dalsgaard, T.; Simonsen, U.

    2007-01-01

    Circulating nitrite has recently emerged as an important physiological metabolite that contributes to increase vasodilation during tissue hypoxia. Using a wire myograph, we have investigated how the nitrite-dependent vasodilation in rat aortic rings is controlled by oxygen tension, norepinephrine...

  17. 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.

  18. determination of nitrite, nitrate and total nitrogen in vegetable samples

    African Journals Online (AJOL)

    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 ...

  19. 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...

  20. Occurrence and Toxicological Significance of Nitrate and Nitrite in ...

    African Journals Online (AJOL)

    Aim: To determine and evaluate the levels of nitrate and nitrite in some commercial infant formula in view of the health implications of these factors. Method: Nitrate and nitrite, which may create significant health problems in infants, were determined in four commercial infant formula. The public health and toxicological ...

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

    OpenAIRE

    Merino, Leonardo; Darnerudc, Per Ola; Toldrá Vilardell, Fidel; Ilbäckc, 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 ...

  2. Increased consumption and vasodilatory effect of nitrite during exercise

    Science.gov (United States)

    Hon, Yuen Yi; Lin, Elaina E.; Tian, Xin; Yang, Yang; Sun, He; Swenson, Erik R.; Taveira-Dasilva, Angelo M.; Gladwin, Mark T.

    2015-01-01

    This study investigated the effects of aerobic-to-anaerobic exercise on nitrite stores in the human circulation and evaluated the effects of systemic nitrite infusion on aerobic and anaerobic exercise capacity and hemodynamics. Six healthy volunteers were randomized to receive sodium nitrite or saline for 70 min in two separate occasions in an exercise study. Subjects cycled on an upright electronically braked cycle ergometer 30 min into the infusion according to a ramp protocol designed to attain exhaustion in 10 min. They were allowed to recover for 30 min thereafter. The changes of whole blood nitrite concentrations over the 70-min study period were analyzed by pharmacokinetic modeling. Longitudinal measurements of hemodynamic and clinical variables were analyzed by fitting nonparametric regression spline models. During exercise, nitrite consumption/elimination rate was increased by ∼137%. Cardiac output (CO), mean arterial pressure (MAP), and pulmonary artery pressure (PAP) were increased, but smaller elevation of MAP and larger increases of CO and PAP were found during nitrite infusion compared with placebo control. The higher CO and lower MAP during nitrite infusion were likely attributed to vasodilation and a trend toward decrease in systemic vascular resistance. In contrast, there were no significant changes in mean pulmonary artery pressures and pulmonary vascular resistance. These findings, together with the increased consumption of nitrite and production of iron-nitrosyl-hemoglobin during exercise, support the notion of nitrite conversion to release NO resulting in systemic vasodilatation. However, at the dosing used in this protocol achieving micromolar plasma concentrations of nitrite, exercise capacity was not enhanced, as opposed to other reports using lower dosing. PMID:26684248

  3. 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

  4. Upconversion nanoparticles for ratiometric fluorescence detection of nitrite.

    Science.gov (United States)

    Han, Junfen; Zhang, Cheng; Liu, Fei; Liu, Bianhua; Han, Mingyong; Zou, Wensheng; Yang, Liang; Zhang, Zhongping

    2014-06-21

    We have developed a selective upconversion switching method for the ratiometric fluorescence detection of nitrite using upconversion nanoparticles (UCNPs) and an efficient nitrite reaction. The green emission (λ(em) = 539 nm) of NaYF4:Yb(3+),Er(3+) nanoparticles can be selectively quenched by the neutral red (NR) dye due to the spectral overlap between the emission at 539 nm and the absorption of NR, while its red emission (λ(em) = 654 nm) remains unchanged. Nitrite reacts specifically and strongly with NR to form diazonium salt and lose the diazonium group, which sharply decreases the absorption of NR. Thus, the green emission of NaYF4:Yb(3+),Er(3+) can be recovered by increasing the amount of nitrite, leading to visible color changes from red to orange-yellow and finally green under excitation at 980 nm. The increase in the ratio of emission intensities (I539/I654) is quantitatively correlated to the concentration of nitrite ions. Moreover, the developed method has been successfully applied to nitrite detection in real samples such as drinking water, natural water and meat foods. In particular, the upconversion sensors can efficiently avoid background optical interference and thus show potential for the detection of nitrite salts in complex samples.

  5. Community analysis of ammonia and nitrite oxidizers during start-up of nitritation reactors.

    Science.gov (United States)

    Egli, Konrad; Langer, Christian; Siegrist, Hans-Ruedi; Zehnder, Alexander J B; Wagner, Michael; van der Meer, Jan Roelof

    2003-06-01

    Partial nitrification of ammonium to nitrite under oxic conditions (nitritation) is a critical process for the effective use of alternative nitrogen removal technologies from wastewater. Here we investigated the conditions which promote establishment of a suitable microbial community for performing nitritation when starting from regular sewage sludge. Reactors were operated in duplicate under different conditions (pH, temperature, and dilution rate) and were fed with 50 mM ammonium either as synthetic medium or as sludge digester supernatant. In all cases, stable nitritation could be achieved within 10 to 20 days after inoculation. Quantitative in situ hybridization analysis with group-specific fluorescent rRNA-targeted oligonucleotides (FISH) in the different reactors showed that nitrite-oxidizing bacteria of the genus Nitrospira were only active directly after inoculation with sewage sludge (up to 4 days and detectable up to 10 days). As demonstrated by quantitative FISH and restriction fragment length polymorphism (RFLP) analyses of the amoA gene (encoding the active-site subunit of the ammonium monooxygenase), the community of ammonia-oxidizing bacteria changed within the first 15 to 20 days from a more diverse set of populations consisting of members of the Nitrosomonas communis and Nitrosomonas oligotropha sublineages and the Nitrosomonas europaea-Nitrosomonas eutropha subgroup in the inoculated sludge to a smaller subset in the reactors. Reactors operated at 30 degrees C and pH 7.5 contained reproducibly homogeneous communities dominated by one amoA RFLP type from the N. europaea-N. eutropha group. Duplicate reactors at pH 7.0 developed into diverse communities and showed transient population changes even within the ammonia oxidizer community. Reactors at pH 7.5 and 25 degrees C formed communities that were indistinguishable by the applied FISH probes but differing in amoA RFLP types. Communities in reactors fed with sludge digester supernatant exhibited a

  6. Impact of mitochondria on nitrite metabolism in HL-1 cardiomyocytes

    Directory of Open Access Journals (Sweden)

    Peter eDungel

    2013-05-01

    Full Text Available Apart from ATP synthesis mitochondria have many other functions, one being nitrite reductase activity. NO released from nitrite has been shown to protect the heart from ischemia/reperfusion injury in a cGMP-dependent manner. However, the exact impact of mitochondria on the release of NO from nitrite in cardiomyocytes is not completely understood. Besides mitochondria, a number of non-mitochondrial metalloproteins have been suggested to facilitate this process. The aim of this study was to investigate the impact of mitochondria on the bioactivation of nitrite in HL-1 cardiomyocytes.The levels of nitrosyl complexes of hemoglobin (NO-Hb and cGMP levels were measured by electron spin resonance spectroscopy and enzyme immunoassay. In addition the formation of free NO was determined by confocal microscopy as well as intracellular nitrite and S-nitrosothiols by chemoluminescence analysis. NO was released from nitrite in cell culture in an oxygen dependent manner. Application of specific inhibitors of the respiratory chain, p450, NO synthases and xanthine oxidoreductase showed that all four enzymatic systems are involved in the release of NO, but more than 50% of NO is released via the mitochondrial pathway. Only NO released by mitochondria activated cGMP synthesis. Cardiomyocytes co-cultured with red blood cells (RBC competed with RBC for nitrite, but free NO was detected only in HL-1 cells suggesting that RBC are not a source of NO in this model. Apart from activation of cGMP synthesis, NO formed in HL-1 cells diffused out of the cells and formed NO-Hb complexes. In addition nitrite was converted by HL-1 cells to S-nitrosyl complexes. In HL-1 cardiomyocytes, several enzymatic systems are involved in nitrite reduction to NO but only the mitochondrial pathway of NO release activates cGMP synthesis. Our data suggest that this pathway may be a key regulator of myocardial contractility especially under hypoxic conditions.

  7. Estimated Dietary Intake of Nitrite and Nitrate in Swedish Children

    OpenAIRE

    2011-01-01

    Abstract This study examined the intake of nitrate and nitrite in Swedish children. Daily intake estimates were based on a nationwide food consumption survey (4-day food diary) and nitrite/nitrate content in vegetables, fruit, cured meat and water. The mean intake of nitrite from cured meat among 2259 children studied was 0.013, 0.010 and 0.007 mg kg-1 body weight day-1 in age groups 4, 8-9 and 11-12, respectively. Among these age groups, three individuals (0.1% of the studied chil...

  8. Nitrite Formation from Hydroxylamine and Oximes by Pseudomonas aeruginosa

    Science.gov (United States)

    Amarger, Noelle; Alexander, M.

    1968-01-01

    Nitrite was formed from hydroxylamine and several oximes by intact cells and extracts of Pseudomonas aeruginosa. The activity was induced by the presence of oximes in the culture medium. Nitroalkanes were not intermediates in the conversion of acetaldoxime, acetone oxime, or butanone oxime to nitrite, since nitromethane inhibited the formation of nitrite from the nitro compounds but not from the corresponding oximes. The oxime apparently functions as a constant source of hydroxylamine during growth of the bacterium. Hydroxylamine at low concentration was converted stoichiometrically to nitrite by extracts of the bacterium; high concentrations were inhibitory. Nicotinamide adenine dinucleotide phosphate, oxygen, and other unidentified cofactors were necessary for the reaction. Actively nitrifying extracts possessed no hydroxylamine-cytochrome c reductase activity. Hyponitrite, nitrous oxide, and nitric oxide were not metabolized. PMID:4384968

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

    DEFF Research Database (Denmark)

    Farver, Ole; Brunori, Maurizio; Cutruzzolà, Francesca

    2009-01-01

    The cd(1) nitrite reductases, which catalyze the reduction of nitrite to nitric oxide, are homodimers of 60 kDa subunits, each containing one heme-c and one heme-d(1). Heme-c is the electron entry site, whereas heme-d(1) constitutes the catalytic center. The 3D structure of Pseudomonas aeruginosa...... is controlling this internal ET step. In this study we have investigated the internal ET in the wild-type and His369Ala mutant of P. aeruginosa nitrite reductases and have observed similar cooperativity to that of the Pseudomonas stutzeri enzyme. Heme-c was initially reduced, in an essentially diffusion...... nitrite reductase has been determined in both fully oxidized and reduced states. Intramolecular electron transfer (ET), between c and d(1) hemes is an essential step in the catalytic cycle. In earlier studies of the Pseudomonas stutzeri enzyme, we observed that a marked negative cooperativity...

  10. Reevaluation of nitrate and nitrite levels in the human intestine.

    Science.gov (United States)

    Saul, R L; Kabir, S H; Cohen, Z; Bruce, W R; Archer, M C

    1981-06-01

    Analyses of human fecal and ileostomy samples by a method that is insensitive and free from interferences indicate that nitrate and nitrite levels in the intestine are lower than reported previously. Fecal nitrate and nitrite concentrations ranged from 0 to 14 mumol/kg (0 to 0.9 ppm) and 5 to 19 mumol/kg (0.3 to 0.9 ppm), respectively. Ileostomy samples contained from 0 to 7 mumol/kg (0 to 0.4 ppm) and 0 to 15 mumol/kg (0 to 0.7 ppm) for nitrate and nitrite, respectively. We also showed that, when deliberately added to feces samples, nitrate and nitrite were destroyed during a two-hr incubation period in a reaction that depended on the presence of microorganisms. The results suggest that conditions in the lower gastrointestinal tract favor denitrification, not nitrification as had been proposed previously.

  11. Achievement of high nitrite accumulation via endogenous partial denitrification (EPD).

    Science.gov (United States)

    Ji, Jiantao; Peng, Yongzhen; Wang, Bo; Wang, Shuying

    2017-01-01

    This study proposed a novel strategy for achievement of partial denitrification driven by endogenous carbon sources in an anaerobic/anoxic/aerobic activated sludge system. Results showed that in the steady-stage, the nitrate-to-nitrite transformation ratio (NTR) was kept at around 87% without nitrate in the effluent. During the anaerobic period, exogenous carbon sources was completely taken up, accompanied by the consumption of glycogen and production of polyhydroxyalkanoates (PHAs). During the anoxic period, nitrate was reduced to nitrite by using PHAs as carbon sources, followed by the replenishment of glycogen. Thus, the phenotype of denitrifying GAOs was clearly observed and endogenous partial denitrification (EPD) occurred. Furthermore, results showed the nitrate reduction was prior to the nitrite reduction in the presence of nitrate, which led to the high nitrite accumulation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. 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 .

  13. Nitrite formation from hydroxylamine and oximes by Pseudomonas aeruginosa.

    Science.gov (United States)

    Amarger, N; Alexander, M

    1968-05-01

    Nitrite was formed from hydroxylamine and several oximes by intact cells and extracts of Pseudomonas aeruginosa. The activity was induced by the presence of oximes in the culture medium. Nitroalkanes were not intermediates in the conversion of acetaldoxime, acetone oxime, or butanone oxime to nitrite, since nitromethane inhibited the formation of nitrite from the nitro compounds but not from the corresponding oximes. The oxime apparently functions as a constant source of hydroxylamine during growth of the bacterium. Hydroxylamine at low concentration was converted stoichiometrically to nitrite by extracts of the bacterium; high concentrations were inhibitory. Nicotinamide adenine dinucleotide phosphate, oxygen, and other unidentified cofactors were necessary for the reaction. Actively nitrifying extracts possessed no hydroxylamine-cytochrome c reductase activity. Hyponitrite, nitrous oxide, and nitric oxide were not metabolized.

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

    DEFF Research Database (Denmark)

    Jensen, Frank Bo; Hansen, Marie N.

    2011-01-01

    cells (RBCs) and muscle tissue of normoxic than hypoxic goldfish, suggesting that nitrite uptake was augmented by normoxia in spite of a predictable lower gill surface area. Elevation of nitrite was associated with increased concentrations of S-nitroso, N-nitroso and Fe-nitrosyl compounds in both......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...... 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...

  15. Model based evaluation of partial nitritation in a SHARON reactor

    OpenAIRE

    Magrí Aloy, Albert; Solé-Mauri, Francina; Colprim, Jesús; Flotats Ripoll, Xavier

    2007-01-01

    The CLONIC ‘Closing the Nitrogen Cycle from Urban Landfill Leachate by Biological Nitrogen Removal over Nitrite and Thermal Treatment’ project is focused on nitrogen removal through the application of two biological processes: a partial nitritation of ammonia followed by an anaerobic ammonium oxidation (anammox). Finally, a thermal dry treatment closes the cycle. This CLONIC project workshop will present final results and will give researchers the opportunity to share their experiences in ...

  16. Nitrate, Nitrite and ascorbic acid content of commercial and home ...

    African Journals Online (AJOL)

    The contents of nitrate, nitrite and ascorbic acid were determined in four samples of commercial and fifteen samples of home - prepared complementary infant foods common in Nigeria. The nitrate and nitrite values of the commercial food samples ranged from 3.1– 3.9mgNO3- N/100g and 5.0 - 16.0ug N02 - N/100g ...

  17. 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

  18. 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.

  19. Nitrite therapy improves survival postexposure to chlorine gas

    Science.gov (United States)

    Honavar, Jaideep; Doran, Stephen; Oh, Joo-Yeun; Steele, Chad; Matalon, Sadis

    2014-01-01

    Exposure to relatively high levels of chlorine (Cl2) gas can occur in mass-casualty scenarios associated with accidental or intentional release. Recent studies have shown a significant postexposure injury phase to the airways, pulmonary, and systemic vasculatures mediated in part by oxidative stress, inflammation, and dysfunction in endogenous nitric oxide homeostasis pathways. However, there is a need for therapeutics that are amenable to rapid and easy administration in the field and that display efficacy toward toxicity after chlorine exposure. In this study, we tested whether nitric oxide repletion using nitrite, by intramuscular injection after Cl2 exposure, could prevent Cl2 gas toxicity. C57bl/6 male mice were exposed to 600 parts per million Cl2 gas for 45 min, and 24-h survival was determined with or without postexposure intramuscular nitrite injection. A single injection of nitrite (10 mg/kg) administered either 30 or 60 min postexposure significantly improved 24-h survival (from ∼20% to 50%). Survival was associated with decreased neutrophil accumulation in the airways. Rendering mice neutropenic before Cl2 exposure improved survival and resulted in loss of nitrite-dependent survival protection. Interestingly, female mice were more sensitive to Cl2-induced toxicity compared with males and were also less responsive to postexposure nitrite therapy. These data provide evidence for efficacy and define therapeutic parameters for a single intramuscular injection of nitrite as a therapeutic after Cl2 gas exposure that is amenable to administration in mass-casualty scenarios. PMID:25326579

  20. 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.

  1. Nitrite therapy improves survival postexposure to chlorine gas.

    Science.gov (United States)

    Honavar, Jaideep; Doran, Stephen; Oh, Joo-Yeun; Steele, Chad; Matalon, Sadis; Patel, Rakesh P

    2014-12-01

    Exposure to relatively high levels of chlorine (Cl₂) gas can occur in mass-casualty scenarios associated with accidental or intentional release. Recent studies have shown a significant postexposure injury phase to the airways, pulmonary, and systemic vasculatures mediated in part by oxidative stress, inflammation, and dysfunction in endogenous nitric oxide homeostasis pathways. However, there is a need for therapeutics that are amenable to rapid and easy administration in the field and that display efficacy toward toxicity after chlorine exposure. In this study, we tested whether nitric oxide repletion using nitrite, by intramuscular injection after Cl₂ exposure, could prevent Cl₂ gas toxicity. C57bl/6 male mice were exposed to 600 parts per million Cl₂ gas for 45 min, and 24-h survival was determined with or without postexposure intramuscular nitrite injection. A single injection of nitrite (10 mg/kg) administered either 30 or 60 min postexposure significantly improved 24-h survival (from ∼20% to 50%). Survival was associated with decreased neutrophil accumulation in the airways. Rendering mice neutropenic before Cl₂ exposure improved survival and resulted in loss of nitrite-dependent survival protection. Interestingly, female mice were more sensitive to Cl₂-induced toxicity compared with males and were also less responsive to postexposure nitrite therapy. These data provide evidence for efficacy and define therapeutic parameters for a single intramuscular injection of nitrite as a therapeutic after Cl₂ gas exposure that is amenable to administration in mass-casualty scenarios. Copyright © 2014 the American Physiological Society.

  2. Nitrogen removal from landfill leachate via the nitrite route

    Directory of Open Access Journals (Sweden)

    D. Kulikowska

    2012-06-01

    Full Text Available The feasibility of removing nitrogen from mature landfill leachate using the nitrite route was investigated in a two-stage SBR system - (1º first stage, short-cut nitrification; second stage, denitrification via nitrite. With a volumetric exchange rate (n of 0.3 d-1 and an oxygen concentration of between 1.2 and 1.3 mg/L, the nitrite accumulation ratio - (NO2-N×100/(NOx-N% - was between 32% and 37%. For the same hydraulic retention time, but lower oxygen concentration - between 0.8 and 0.9 mg/L - nitrite accumulation averaged 96%, indicating that ammonia was removed completely via the nitrite pathway. In the second step, an external carbon source was added to promote denitrification. Complete removal of nitrite was obtained for a carbon dose of 2.4 mg COD/mg NO2-N using acetic acid and 3.8 mg COD/mg NO2-N for butyric acid. Also, a higher denitrification rate - 14.6 mg NO2-N/g VSS∙h - was observed with butyric acid as compared with acetic acid - 9.12 mg NO2-N/g VSS∙h.

  3. Nitrate and nitrite content of human, formula, bovine, and soy milks: implications for dietary nitrite and nitrate recommendations.

    Science.gov (United States)

    Hord, Norman G; Ghannam, Janine S; Garg, Harsha K; Berens, Pamela D; Bryan, Nathan S

    2011-12-01

    Estimation of nitrate and nitrite concentrations of milk sources may provide insight into potential health risks and benefits of these food sources for infants, children, and adults. The World Health Organization and American Academy of Pediatrics recommends exclusive consumption of human milk for the first 6 months of life. Human milk is known to confer significant nutritional and immunological benefits for the infant. Consumption of formula, cow's, and soy milk may be used as alternatives to human milk for infants. We sought to estimate potential exposure to nitrate and nitrite in human, formula, bovine, and soy milk to inform total dietary exposure estimates and recommendations. Using sensitive quantitative methodologies, nitrite and nitrate were analyzed in different samples of milk. Human milk concentrations of colostrum (expressed days 1-3 postpartum; n=12), transition milk (expressed days 3-7 postpartum; n=17), and mature milk (expressed >7 days postpartum; n=50) were 0.08 mg/100 mL nitrite and 0.19 mg/100 mL nitrate, 0.001 mg/100 mL nitrite and 0.52 mg/100 mL nitrate, and 0.001 mg/100 mL nitrite and 0.3 mg/100 mL nitrate, respectively, revealing that the absolute amounts of these anions change as the composition of milk changes. When expressed as a percentage of the World Health Organization's Acceptable Daily Intake limits, Silk® Soy Vanilla (WhiteWave Foods, Broomfield, CO) intake could result in high nitrate intakes (104% of this standard), while intake of Bright Beginnings Soy Pediatric® formula (PBM Nutritionals, Georgia, VT) could result in the highest nitrite intakes (383% of this standard). The temporal relationship between the provision of nitrite in human milk and the development of commensal microbiota capable of reducing dietary nitrate to nitrite supports a hypothesis that humans are adapted to provide nitrite to the gastrointestinal tract from birth. These data support the hypothesis that the high concentrations of

  4. 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.

  5. 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

    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.

  6. 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

  7. [A nitrite poisoning event associated with intentional chemical releases].

    Science.gov (United States)

    Li, Gang; Li, Bin; Lin, Lin; Zhang, Mao-tang; Liu, Qu; Huang, Wei; Xie, Xian-qing; Chen, Lin; Zhang, Shun-xiang

    2013-04-01

    To compare the field epidemiological investigation and the criminal investigation on a nitrite poisoning event caused by deliberate contamination. Cases were searched according to the definition of the disease. Information on the histories of onset and diet of all the cases and normal population on site, were investigated face to face. Information as ingredients, processing and sales of foods was also gathered. Samples were collected and nitrite detection were performed. Relevant materials were searched, cases were interviewed and data related to criminal results were collected. Poisoned persons were staff of a big company in Longgang district of Shenzhen. The overall attack rate was 56.25% (63/112), with suspected and confirmed rates as 41.96% and 14.28%, respectively. The fatality rate was 3.17% (2/63). Clinical manifestation and effect of treatment were in accordance with the characteristics of an episode related to acute nitrite food poisoning in terms of factors as the time of onset, involving different age, sex and jobs of the patients. A total of 191 samples, including vomits from patients and seven batches of food and environment samples, were collected, with a positive detected rate of nitrite as 18.84%. Information gathered from the field environment, food distribution and processing supported the assumption that this was an incident of nitrite poisoning event with intention. from the criminal investigation showed that the suspect stemmed from the market management rivalry, bought nitrite, dissolved and spread on food stalls F9 and F10. This event of intentional nitrite release resulting in food contamination which further leading to food poisoning, was completely proved by the joint efforts of the teams and expertise from the field epidemiology survey and the criminal investigation.

  8. Taurine-nitrite interaction as a precursor of alkylation mechanisms.

    Science.gov (United States)

    Arenas-Valgañón, Jorge; Gómez-Bombarelli, Rafael; González-Pérez, Marina; González-Jiménez, Mario; Calle, Emilio; Casado, Julio

    2012-09-15

    Taurine (2-aminoethanesulphonic acid) is an amino acid-like-compound widely used as an ingredient in some nutraceuticals and energy drinks. Here the interaction of taurine (Tau) with nitrite was investigated. The reactions were carried out mimicking the conditions of the stomach lumen. The conclusions drawn are as follows: (i) Nitrite showed nitrosating capacity on Tau. The rate equation was ν(N)=k(obs)[Tau](o)[nitrite](o)(2), this result suggesting that the yield of nitrosation products in the human stomach would increase sharply with higher nitrate/nitrite intakes; (ii) the experimental results suggest a mechanism for the nitrosation, whose rate-limiting step is bimolecular attack by N(2)O(3); (iii) the nitrosation of taurine affords ethanesultone (ES), which displays alkylating capacity on the nucleophile 4-(p-nitrobenzyl)pyridine (NBP), a trap for alkylating agents with nucleophilic characteristics similar to those of DNA bases. Although the NBP alkylation rate for ethanesultone is much higher than those for carcinogenic four-membered ring lactones, resulting in the nitrosation of amino carboxylic acids, the fraction of ES-forming adduct with NBP is much smaller; (iv) in spite of the low risk to human health, since the stomach lumen conditions could be a favourable medium for Tau nitrosation, attention should be paid to potential situations of the concurrence of high contents of taurine and nitrite/nitrate in the diet. Copyright © 2012. Published by Elsevier Ltd.

  9. 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.

  10. Nitrite as regulator of hypoxic signaling in mammalian physiology

    Science.gov (United States)

    van Faassen, Ernst E.; Bahrami, Soheyl; Feelisch, Martin; Hogg, Neil; Kelm, Malte; Kim-Shapiro, Daniel B.; Kozlov, Andrey V.; Li, Haitao; Lundberg, Jon O.; Mason, Ron; Nohl, Hans; Rassaf, Tienush; Samouilov, Alexandre; Slama-Schwok, Anny; Shiva, Sruti; Vanin, Anatoly F.; Weitzberg, Eddie; Zweier, Jay; Gladwin, Mark T.

    2009-01-01

    In this review we consider the physiological effects of endogenous and pharmacological levels of nitrite under conditions of hypoxia. In humans, the nitrite anion has long been considered as metastable intermediate in the oxidation of nitric oxide radicals to the stable metabolite nitrate. This oxidation cascade was thought to be irreversible under physiological conditions. However, a growing body of experimental observations attests that the presence of endogenous nitrite regulates a number of signaling events along the physiological and pathophysiological oxygen gradient. Hypoxic signaling events include vasodilation, modulation of mitochondrial respiration, and cytoprotection following ischemic insult. These phenomena are attributed to the reduction of nitrite anions to nitric oxide if local oxygen levels in tissues decrease. Recent research identified a growing list of enzymatic and non-enzymatic pathways for this endogenous reduction of nitrite. Additional direct signaling events not involving free nitric oxide are proposed. We here discuss the mechanisms and properties of these various pathways and the role played by the local concentration of free oxygen in the affected tissue. PMID:19219851

  11. Molybdenum-containing nitrite reductases: Spectroscopic characterization and redox mechanism.

    Science.gov (United States)

    Wang, Jun; Keceli, Gizem; Cao, Rui; Su, Jiangtao; Mi, Zhiyuan

    2017-01-01

    This review summarizes the spectroscopic results, which will provide useful suggestions for future research. In addition, the fields that urgently need more information are also advised. Nitrite-NO-cGMP has been considered as an important signaling pathway of NO in human cells. To date, all the four known human molybdenum-containing enzymes, xanthine oxidase, aldehyde oxidase, sulfite oxidase, and mitochondrial amidoxime-reducing component, have been shown to function as nitrite reductases under hypoxia by biochemical, cellular, or animal studies. Various spectroscopic techniques have been applied to investigate the structure and catalytic mechanism of these enzymes for more than 20 years. We summarize the published data on the applications of UV-vis and EPR spectroscopies, and X-ray crystallography in studying nitrite reductase activity of the four human molybdenum-containing enzymes. UV-vis has provided useful information on the redox active centers of these enzymes. The utilization of EPR spectroscopy has been critical in determining the coordination and redox status of the Mo center during catalysis. Despite the lack of substrate-bound crystal structures of these nitrite reductases, valuable structural information has been obtained by X-ray crystallography. To fully understand the catalytic mechanisms of these physiologically/pathologically important nitrite reductases, structural studies on substrate-redox center interaction are needed.

  12. Nitrite therapy prevents chlorine gas toxicity in rabbits.

    Science.gov (United States)

    Honavar, Jaideep; Doran, Stephen; Ricart, Karina; Matalon, Sadis; Patel, Rakesh P

    2017-04-05

    Chlorine (Cl 2 ) gas exposure and toxicity remains a concern in military and industrial sectors. While post-Cl 2 exposure damage to the lungs and other tissues has been documented and major underlying mechanisms elucidated, no targeted therapeutics that are effective when administered post-exposure, and which are amenable to mass-casualty scenarios have been developed. Our recent studies show nitrite administered by intramuscular (IM) injection post-Cl 2 exposure is effective in preventing acute lung injury and improving survival in rodent models. Our goal in this study was to develop a rabbit model of Cl 2 toxicity and test whether nitrite affords protection in a non-rodent model. Exposure of New Zealand White rabbits to Cl 2 gas (600ppm, 45min) caused significant increases in protein and neutrophil accumulation in the airways and ∼35% mortality over 18h. Nitrite administered 30min post Cl 2 exposure by a single IM injection, at 1mg/kg or 10mg/kg, prevented indices of acute lung injury at 6h by up to 50%. Moreover, all rabbits that received nitrite survived over the study period. These data provide further rationale for developing nitrite as post-exposure therapeutic to mitigate against Cl 2 gas exposure injury. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Nitrite production from urine for sulfide control in sewers.

    Science.gov (United States)

    Zheng, Min; Zuo, Zhiqiang; Zhang, Yizhen; Cui, Yujia; Dong, Qian; Liu, Yanchen; Huang, Xia; Yuan, Zhiguo

    2017-10-01

    Most commonly used methods for sewer sulfide control involves dosing chemical agents to wastewater, which incurs high operational costs. Here, we propose and demonstrate a cost-effective and environmentally attractive approach to sewer sulfide control through urine separation and its subsequent conversion to nitrite prior to intermittent dosage to sewers. Urine collected from a male toilet urinal was fed to laboratory-scale sequencing batch reactors. The reactors stably converted roughly 50% of the nitrogen in urine to nitrite, with high abundance (at 17.46%) of known ammonia-oxidizing bacteria (AOB) of the genus Nitrosomonas, and absence (below detection level) of typical nitrite-oxidizing bacteria of the genus Nitrospira, according to 454 pyrosequencing analysis. The stable nitrite production was achieved at both relatively high (1.0-2.0 mg/L) and low (0.2-0.3 mg/L) dissolved oxygen concentrations. Dosing tests in laboratory-scale sewer systems confirmed the sulfide control effectiveness of free nitrous acid generated from urine. Life cycle assessment indicated that, compared with commodity chemicals, nitrite/free nitrous acid (FNA) production from urine for sulfide control in sewers would lower the operational costs by approximately 2/3 and greenhouse gas (GHG) emissions by 1/3 in 20 years. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. 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 ...

  15. Calcium carbonate overdose

    Science.gov (United States)

    Tums overdose; Calcium overdose ... Calcium carbonate can be dangerous in large amounts. ... Some products that contain calcium carbonate are certain: ... and mineral supplements Other products may also contain calcium ...

  16. Reduction of nitrate and nitrite salts under hydrothermal conditions

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-10-01

    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.

  17. Recent structural insights into the function of copper nitrite reductases.

    Science.gov (United States)

    Horrell, Sam; Kekilli, Demet; Strange, Richard W; Hough, Michael A

    2017-11-15

    Copper nitrite reductases (CuNiR) carry out the first committed step of the denitrification pathway of the global nitrogen cycle, the reduction of nitrite (NO 2 - ) to nitric oxide (NO). As such, they are of major agronomic and environmental importance. CuNiRs occur primarily in denitrifying soil bacteria which carry out the overall reduction of nitrate to dinitrogen. In this article, we review the insights gained into copper nitrite reductase (CuNiR) function from three dimensional structures. We particularly focus on developments over the last decade, including insights from serial femtosecond crystallography using X-ray free electron lasers (XFELs) and from the recently discovered 3-domain CuNiRs.

  18. The anoxic plant mitochondrion as a nitrite: NO reductase.

    Science.gov (United States)

    Gupta, Kapuganti J; Igamberdiev, Abir U

    2011-07-01

    Under the conditions of oxygen deprivation, accumulating nitrite can be reduced in the mitochondrial electron transport chain forming free radical nitric oxide (NO). By reducing nitrite to NO, plant mitochondria preserve the capacity to oxidize external NADH and NADPH and retain a limited power for ATP synthesis complementing glycolytic ATP production. NO participates in O(2) balance in mitochondria by competitively inhibiting cytochrome c oxidase which can oxidize it to nitrite when oxygen concentration increases. Some of the NO escapes to the cytosol, where the efficient scavenging system involving non-symbiotic hemoglobin oxygenates NO to nitrate and supports continuous anaerobic turnover of nitrogen species. © 2011 Elsevier B.V. and Mitochondria Research Society. All rights reserved.

  19. Absorption of atmospheric nitrogen dioxide by plants and soils. II. Nitrite accumulation, nitrite reductase activity and diurnal change of nitrogen dioxide absorption in leaves

    Energy Technology Data Exchange (ETDEWEB)

    Yoneyama, T.; Sasakawa, H.; Ishizuka, S.; Totsuka, T.

    1979-01-01

    NO/sub 2/ uptake by leaves and reduction systems of nitrite produced were investigated using 3-week-old kidney bean, sunflower, and corn plants, which were grown in vermiculite beds supplied with tap water. The plants were fumigated with ppM NO/sub 2/ for 6 hr in an artificially-lit chamber (30 klux), and the following things were observed. Fumigation in the light at daytime caused severe injury (wilting) in kidney bean leaves, and slight injury in sunflower leaves, but corn leaves were tolerant to this treatment. A high concentration of nitrite rapidly accumulted in the kidney bean leaves, but the nitrite reductase activity was only increased to a small extent. In sunflower leaves a high concentration of nitrite was accumulated, and the nitrite reductase activity also increased rapidly. Fumigation in the dark at nighttime caused low concentration of nitrite to accumulate in the kidney bean and sunflower leaves, and it was leveled down at the later fumigation time. The nitrite reductase activity of the two plants was increased with a slow rate continuously during the NO/sub 2/ fumigation period. On the other hand, in the corn leaves, nitrite was not detected in the daytime, but only a low concentration of nitrite was detected in the nighttime. A high activity of nitrite reductase was detected compared with the other two plants. Application of nitrite through the culture solution reduced nitrite accumulation in the light but not in the dark. These results indicate that acute NO/sub 2/ injury is mainly related to nitrite accumulation. Therefore, low NO/sub 2/ absorption and high nitrite reductase activity (including its rapid induction) may reduce injury in leaves. Absorption of /sup 15/NO/sub 2/ at night by sunflower leaves was around 14% that at daytime. These indicate that a diurnal change of NO/sub 2/ uptake is operating. 14 references, 2 figures, 3 tables.

  20. 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.

  1. Spectrophotometric determination of nitrite by its catalytic effect on ...

    African Journals Online (AJOL)

    Under the optimum experimental conditions (sulfuric acid, 0.3 M; CR, 0.75x10-4 M; potassium bromate, 5x10-4 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. PENGARUH PENAMBAHAN UREA TERHADAP PENINGKATAN PENCEMARAN NITRIT DAN NITRAT DALAM TANAH (Influence of Addition of Urea to Increased Pollution of Nitrite and Nitrate in The Soil

    Directory of Open Access Journals (Sweden)

    Aida Mawaddah

    2016-09-01

    Full Text Available ABSTRAK Nitrat dan nitrit merupakan sumber nitrogen bagi tanaman. Nitrogen sangat diperlukan tanaman untuk pertumbuhan dan perkembangan. Bentuk-bentuk nitrogen di lingkungan mengalami transformasi sebagai bagian dari siklus nitrogen seperti nitrifikasi dan denitrifikasi. Apabila kadar nitrogen dalam tanah rendah, maka urea digunakan sebagai sumber nitrogen. Perubahan urea menjadi nitrit atau nitrat pada beberapa sampel tanah perlu diketahui. Kadar nitrit dan nitrat yang tinggi dapat meningkatkan pencemaran di dalam tanah. Sampel tanah yang digunakan dalam penelitian ini adalah tanah pasir, tanah sawah, tanah pupuk kompos dan tanah pupuk kandang. Analisis nitrit dan nitrat dilakukan dengan menggunakan pereaksi asam p-amino benzoat (PABA yang dikopling dengan N-naftiletilendiamin (NEDA dan reduktor spongy cadmium. Sebelum digunakan untuk analisis nitrit dan nitrat, metode divalidasi terlebih dahulu. Hasil validasi metode analisis nitrit dan nitrat dengan pereaksi PABA/NEDA menunjukkan persentase perolehan kembali masing-masing antara 87,15–100,8% untuk nitrit dan 88,16–105,7% untuk nitrat. Setelah ditambah urea sebesar 0,66 g.kg-1 ke dalam tanah, konsentrasi nitrit dan nitrat pada semua sampel tanah mengalami peningkatan. Dari penelitian ini diketahui bahwa peningkatan kadar nitrit dan nitrat setelah ditambahkan urea sangat dipengaruhi oleh kondisi tanah.   ABSTRACT Nitrate and nitrite were sources of nitrogen for plants. Nitrogen is indispensable for the growth and development of plants. The forms of nitrogen in the environment undergoes a transformation as part of the nitrogen cycle like nitrification and denitrification. If nitrogen level in the soil is low, urea is used as a source of nitrogen. Changes of urea into nitrite or nitrate in some of soil samples need to be known. The levels of nitrite and nitrate are high can increase pollution in the soil. Some of soil samples which is used in this research were sandy soil, paddy soil

  3. Nitrosylation of myoglobin and nitrosation of cysteine by nitrite in a model system simulating meat curing.

    Science.gov (United States)

    Sullivan, Gary A; Sebranek, Joseph G

    2012-02-22

    Demand is growing for meat products cured without the addition of sodium nitrite. Instead of the direct addition of nitrite to meat in formulation, nitrite is supplied by bacterial reduction of natural nitrate often added as vegetable juice/powder. However, the rate of nitrite formation in this process is relatively slow, and the total ingoing nitrite is typically less than in conventional curing processes. The objective of this study was to determine the impact of the rate of addition of nitrite and the amount of nitrite added on nitrosylation/nitrosation reactions in a model meat curing system. Myoglobin was preferentially nitrosylated as no decrease in sulfhydryl groups was found until maximum nitrosylmyoglobin color was achieved. The cysteine-myoglobin model retained more sulfhydryl groups than the cysteine-only model (p 0.05). These data suggest that the amount of nitrite but not the rate of addition impacts the nitrosylation/nitrosation reactions this system.

  4. 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...

  5. 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,

  6. Nitrite Interference with Soluble COD Measurements from Aerobically Treated Wastewater.

    Science.gov (United States)

    Ferraz, Fernanda M; Yuan, Qiuyan

    2017-06-01

      This study aimed to determine the interference of nitrite () with soluble chemical oxygen demand (COD) measurements from the effluent of landfill leachate treated by sequencing batch reactors (SBRs). Synthetic wastewater assimilating young and old landfill leachate was used as influent for SBR1 and SBR2, respectively. A mixture of raw wastewater and landfill leachate was used as influent for SBR3. Due to the high ammonia concentration in the influent, different levels of partial nitrification were observed in all the reactors and was detected in the effluents. Theoretically, when is present in the effluent, 1 mg/L of accounts for 1.1 mg/L of COD (i.e., 1.1 mg COD/mg ) due to the oxidation of to . It was found that the value of 1.1 mg COD/mg was 3 times higher than the values obtained in the experiments with SBR1 and SBR3. In addition, the values obtained in the experiments with SBR2 were much higher than 1.1 mg COD/mg . These results suggest that the theoretical value of 1.1 mg COD/mg cannot be applied to predict the COD values caused by nitrite in the tested wastewaters. To obtain an accurate measurement of soluble COD in samples that contain nitrite, nitrite should be eliminated before the measurements.

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

    African Journals Online (AJOL)

    STORAGESEVER

    2010-03-01

    Mar 1, 2010 ... somatic embryogenesis stages, and that the level of GhNiR mRNA was also higher in the cultivar with higher somatic ..... Planta, 183: 17-24. Alexander H, Treusch, Sven L, Arnulf K, Stephan CS, Hans-Peter K,. Christa S (2005). Novel genes for nitrite reductase and Amo-related proteins indicate a role of ...

  8. Electrochemical removal of nitrite in simulated aquaculture wastewater

    African Journals Online (AJOL)

    use

    2011-11-21

    Nov 21, 2011 ... iridium-modified carbon fiber electrodes with various current densities. Specifically, the mechanism of electrochemical nitrite oxidation was reported to involve ..... recycling with pollution abatement. Aquacult. 3: 61-85. Martinez-Huitle CA, Ferro S (2006). Electrochemical oxidation of organic pollutants for the ...

  9. The effects of nitrogen and phosphorus deficiencies and nitrite ...

    African Journals Online (AJOL)

    The effect of 50% N, 100% N, 50% N plus 50% P and 50% P deficiencies and nitrite addition were treated on Chlorella vulgaris (Chlorophyceae) was studied in laboratory conditions with the aim to determine the effects of the deficient nutrient and different nitrogen sources on lipid and protein contents. Protein and lipid ...

  10. 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.

  11. Oxygen exchange between nitrate molecules during nitrite oxidation by Nitrobacter.

    Science.gov (United States)

    DiSpirito, A A; Hooper, A B

    1986-08-15

    During oxidation of nitrite, cells of Nitrobacter winogradskyi are shown to catalyze the active exchange of oxygen atoms between exogenous nitrate molecules (production of 15N16/18O3- during incubation of 14N16/18O3-, 15N16O3-, and 15N16O2- in H216O). Little, if any, exchange of oxygens between nitrate and water also occurs (production of 15N16/18O3- during incubation of 15N16O3- and 14N16O2- in H218O). 15N species of nitrate were assayed by 18O-isotope shift in 15N NMR. Taking into account the O-exchange reactions which occur during nitrite oxidation, H2O is seen to be the source of O in nitrate produced by oxidation of nitrite by N. winogradskyi. The data do not establish whether the nitrate-nitrate O exchange is catalyzed by nitrite oxidase (H2O + HNO2----HNO3 + 2H+ + 2e-) or nitrate reductase (HNO3 + 2H+ + 2e-----HNO2 + H2O) or both enzymes in consort. The nitrate-nitrate exchange reaction suggests the existence of an oxygen derivative of a H2O-utilizing oxidoreductase.

  12. Seasonal Distribution of Nitrate and Nitrite Levels in Eleme Abattoir ...

    African Journals Online (AJOL)

    The study deals with the seasonal distribution of nitrate (NO3) and nitrite (NO2) levels in Eleme Abattoir environment. Samples of soil, surface water and groundwater were collected from areas unaffected and those affected by abattoir activities. For the soils from the affected area and control points respectively, nitrate levels ...

  13. 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 ...

  14. 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. 319.2 Section 319.2 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF... INSPECTION AND CERTIFICATION DEFINITIONS AND STANDARDS OF IDENTITY OR COMPOSITION General § 319.2 Products...

  15. 21 CFR 862.1510 - Nitrite (nonquantitative) test system.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nitrite (nonquantitative) test system. 862.1510 Section 862.1510 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... diagnosis and treatment of uninary tract infection of bacterial origin. (b) Classification. Class I (general...

  16. 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.

  17. Presence of nitrites, nitrates, nitrosamines in the eggs of Intensively ...

    African Journals Online (AJOL)

    A spectrophotometric method was used to assay for nitrosamines and their precursors in eggs (n=5 from each farm), entailing separate analysis of each egg yolk and albumen. The three compounds measured, were detected in all the samples. The nitrates and nitrites levels were significantly higher in the yolk than in the ...

  18. Nitrite-selective ISE based on uranyl salophen derivatives

    NARCIS (Netherlands)

    Wroblewski, Wojciech; Brzozka, Zbigniew; Rudkevich, Dmitry M.; Rudkevich, D.M.; Reinhoudt, David

    1996-01-01

    Anion selectivities of membranes based on uranyl salophen derivatives with substituents at the 4-position are presented. Derivative 2 (with 4-nitro substituent) has been applied to design a nitrite-selective ion-selective electrode (ISE) that shows linear response in the range 1¿3 of pNO2¿ with a

  19. 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.

  20. Lead, Zinc and Nitrite Levels of Staple Crop Cultivars in Ameka and ...

    African Journals Online (AJOL)

    BSN

    Nitrite is present naturally in soils, meats, plants and drinking water. However, under unfavorable conditions, nitrite may enter the food chain via microbial reduction of nitrate thereby endangering human health (Sebecic and Vedrina, 1998). Nitrate may be reduced to nitrite when cooking is carried out in aluminum utensils.

  1. Coronary Calcium Scan

    Science.gov (United States)

    ... Back To Health Topics / Coronary Calcium Scan Coronary Calcium Scan Also known as Calcium Scan Test A coronary calcium scan is a CT scan of your heart that detects and measures the amount of calcium in the walls of your coronary arteries. Overview ...

  2. Ammonia stimulates growth and nitrite-oxidizing activity of Nitrobacter winogradskyi

    OpenAIRE

    Ma, Shouguang; Zhang, Demin; Zhang, Wenjun; Wang, Yinong

    2014-01-01

    The aim of this study was to obtain a nitrite-oxidizing bacterium with high nitrite oxidation activity for controlling nitrite levels. A nitrite-oxidizing bacterium, ZS-1, was isolated from the water of a coastal Pseudosciaena crocea-rearing pond. The strain was identified as Nitrobacter winogradskyi based on the phylogenetic analyses of the 16S ribosomal ribonucleic acid gene and nxrA sequence of ZS-1. Under aerobic condition, the nitrite-oxidizing activity of ZS-1 did not change considerabl...

  3. 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.

  4. 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.

  5. 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 ...

  6. 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 ...

  7. 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 ...

  8. 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 ...

  9. 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. ...

  10. The impact of elevated water nitrite concentration on physiology, growth and feed intake of African catfish Clarias gariepinus (Burchell 1822)

    NARCIS (Netherlands)

    Roques, J.A.C.; Schram, E.; Spanings, T.; Schaik, van T.; Abbink, W.; Boerrigter, J.; Vries, de P.; Vis, van de J.W.; Flik, G.

    2015-01-01

    The nitrite threshold concentration in rearing water of African catfish (Clarias gariepinus) was assessed. African catfish with an initial mean (SD) weight of 219.7 (57.8) g were exposed to an increasing range of water nitrite from 6 (Control) to 928 µM nitrite for 28 days. Mean (SD) plasma nitrite

  11. Two cases of methemoglobinaemia caused by suspected sodium nitrite poisoning

    Directory of Open Access Journals (Sweden)

    Osvaldo Matteucci

    2008-06-01

    Full Text Available Among the causes of acute methemo-globinaemia are the ingestion and inhalation of over 40 oxidising substances, including nitrite, nitrate, carbon monoxide, some medicines, chlorine. The authors describe a case of acute methemoglobinaemia in two people that most probably suffered from food poisoning resulting from the consumption of a preparation of a dish called turkey alla canzanese that contained significant amounts of sodium nitrite. Both subjects who were treated promptly with methylene blue and hyperbaric oxygen therapy room recovered fully. Epidemiological investigations performed to clarify the dynamics of the episode suggested that among the causes of contamination were the swapping of products at the time of sale and the non-compliance to rules for the preparation of foods for human consumption.

  12. 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.

  13. Nitrates and nitrites content of water boreholes and packaged water ...

    African Journals Online (AJOL)

    Nitrate and nitrite levels were determined in forty-three water samples obtained from different locations in Calabar using colorimetric methods. Twenty-three of these samples were packaged water while twenty were borehole water. Nitrate levels were found to be 24.28 ± 9.30μg/ml and 34.57 ± 14.56µ/ml for packaged water ...

  14. Determination of nitrate and nitrite content of Turkish cheeses ...

    African Journals Online (AJOL)

    The levels of nitrate and nitrite were determined in 185 samples of Turkish cheese having high consumption rate. All cheese samples contained nitrate and its level in Turkish white cheese produced from cow's and sheep's milk were found between 0.92 - 22.40 (mean 8.96±4.93) mg/kg and 0.47 - 23.68 (mean 12.35±6.28) ...

  15. 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 ...

  16. Nitrite disrupts multiple physiological functions in aquatic animals

    DEFF Research Database (Denmark)

    Jensen, Frank Bo

    2003-01-01

    Hb), compromising blood O2 transport. Other haem proteins are also oxidised. Hyperventilation is observed, and eventually tissue O2 shortage becomes reflected in elevated lactate concentrations. Heart rate increases rapidly, before any significant elevations in metHb or extracellular potassium occur. This suggests...... species and in some cases also within species. Rainbow trout fall into two groups with regard to susceptibility and physiological response. These two groups are not related to sex but show significant different nitrite uptake rates....

  17. Simple methods to decrease sodium and nitrite contents in hams

    Directory of Open Access Journals (Sweden)

    Talia Franco-Avila

    2015-07-01

    Full Text Available Introduction: Ham is a product highly consumed by society; however it contains some elements that make it a non-recommended food. Thus, it has been attempted to eliminate or reduce those components.Material and Methods: Content of sodium, nitrites, peroxides and total coliforms were compared after processes of Washing (W and Simple Cooking (SC in turkey and pork ham in a cross-sectional analytical experimental study. Furthermore, sensory acceptance of thesamples through an acceptance test of five points was evaluated. One-way ANOVA with post hoc Bonferroni were used to assess the mean difference between groups. The value of p≤0.05 was considered statistically significant.Results: Both processes reduced the amount of sodium in both types of ham in statistically significant way (p≤0.001. The major percentage of reduction was presented with SC: 73.4% for turkey ham and 63.5% for pork ham. Likewise, the higher percentage of nitrite reduction was 50.6% in pork ham with SC technique (p≤0.05. Peroxide index decreased with both techniques in both hams without statistical significance. Total coliforms count was kept constant in all samples. Higher sensory acceptance of W concerning SC in all sensory characteristics was observed.Conclusions: W and SC techniques reduce sodium, nitrite and peroxide index without affecting the sanitation of hams. Furthermore, W is accepted in all sensory categories. We recommend using W technique before consumption of the product.

  18. Hypoxia tolerance, nitric oxide, and nitrite: lessons from extreme animals.

    Science.gov (United States)

    Fago, Angela; Jensen, Frank B

    2015-03-01

    Among vertebrates able to tolerate periods of oxygen deprivation, the painted and red-eared slider turtles (Chrysemys picta and Trachemys scripta) and the crucian carp (Carassius carassius) are the most extreme and can survive even months of total lack of oxygen during winter. The key to hypoxia 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. ©2015 Int. Union Physiol. Sci./Am. Physiol. Soc.

  19. Ammonia stimulates growth and nitrite-oxidizing activity of Nitrobacter winogradskyi.

    Science.gov (United States)

    Ma, Shouguang; Zhang, Demin; Zhang, Wenjun; Wang, Yinong

    2014-01-02

    The aim of this study was to obtain a nitrite-oxidizing bacterium with high nitrite oxidation activity for controlling nitrite levels. A nitrite-oxidizing bacterium, ZS-1, was isolated from the water of a coastal Pseudosciaena crocea-rearing pond. The strain was identified as Nitrobacter winogradskyi based on the phylogenetic analyses of the 16S ribosomal ribonucleic acid gene and nxrA sequence of ZS-1. Under aerobic condition, the nitrite-oxidizing activity of ZS-1 did not change considerably in the range of pH 7-9, but was strongly inhibited by lower (pH = 6) and higher (pH = 10) pH values. The optimum temperature range is 25-32 °C. Lower temperature made the adaptive phase of ZS-1 longer but did not affect its maximum nitrite oxidization rate. The nitrite-oxidizing activity of ZS-1 started to be inhibited by ammonia and nitrate when the concentrations of ammonia and nitrate reached 25 mg L(-1) and 100 mg L(-1), respectively. The inhibition was stronger with higher concentration of ammonia or nitrate. The nitrite-oxidizing activity of ZS-1, however, was not inhibited by high concentration of nitrite (500 mg L(-1)). The nitrite-oxidizing activity of ZS-1 was increased by low ammonia concentration (1 mg L(-1) to 10 mg L(-1)).

  20. The Hepatoprotective Effect of Sodium Nitrite on Cold Ischemia-Reperfusion Injury

    Directory of Open Access Journals (Sweden)

    Wei Li

    2012-01-01

    Full Text Available Liver ischemia-reperfusion injury is a major cause of primary graft non-function or initial function failure post-transplantation. In this study, we examined the effects of sodium nitrite supplementation on liver IRI in either Lactated Ringer's (LR solution or University of Wisconsin (UW solution. The syngeneic recipients of liver grafts were also treated with or without nitrite by intra-peritoneal injection. Liver AST and LDH release were significantly reduced in both nitrite-supplemented LR and UW preservation solutions compared to their controls. The protective effect of nitrite was more efficacious with longer cold preservation times. Liver histological examination demonstrated better preserved morphology and architecture with nitrite treatment. Hepatocellular apoptosis was significantly reduced in the nitrite-treated livers compared their controls. Moreover, liver grafts with extended cold preservation time of 12 to 24 hours demonstrated improved liver tissue histology and function post-reperfusion with either the nitrite-supplemented preservation solution or in nitrite-treated recipients. Interestingly, combined treatment of both the liver graft and recipient did not confer protection. Thus, nitrite treatment affords significant protection from cold ischemic and reperfusion injury to donor livers and improves liver graft acute function post-transplantation. The results from this study further support the potential for nitrite therapy to mitigate ischemia-reperfusion injury in solid organ transplantation.

  1. 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 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.

  2. Assessment of dietary exposure of nitrate and nitrite in France.

    Science.gov (United States)

    Menard, C; Heraud, F; Volatier, J-L; Leblanc, J-C

    2008-08-01

    The aim of this study was to assess the dietary exposure of nitrate and nitrite in France. A total of 13, 657 concentration levels of nitrate and nitrite measured in food, representing 138 and 109 food items, respectively, and coming from French monitoring programmes between 2000 and 2006, were used. Depending on the non-detected and non-quantified analysis treatment, lower and upper concentration mean estimates were calculated for each food item. These were combined with consumption data derived from 1474 adults and 1018 children from the French national individual consumption survey (INCA1), conducted in 1999 and based on a 7-day food record diary. A total of 18% of spinaches, 6% of salads, 10% of cheeses, 8% of meat products and 6% of industrial meat products exceeded the European nitrate maximum level or maximum residual level. A total of 0.4% of industrial meat products and 0.2% of meat products exceeded their European nitrite maximum level or maximum residual level. Nitrate dietary exposure averaged 40% of the acceptable daily intake (ADI; 3.7 mg kg(-1) body weight day(-1)) for adults and 51 - 54% of the ADI for children with the major contributors being, for adults and children, respectively, vegetables (24 and 27% of ADI), potatoes (5 and 11% of ADI), and water (5 and 5% of ADI). The individual nitrate dietary intake of 1.4% (confidence interval (CI(95th)) [0.8; 2.0]) to 1.5% (CI(95th) [0.9; 2.1]) of adults and 7.9% (CI(95th) [6.2; 9.6]) to 8.4% (CI(95th) [6.7; 10.1]) of children were higher than the ADI. Nitrite dietary exposure averaged 33-67% of the ADI (0.06 mg kg(-1) body weight day(-1)) for adults and 67-133% of the ADI for children, with contributions of additive food vectors at 33% of ADI for adults and 50-67% of ADI for children. The individual nitrite dietary intake of 0.7% (CI(95th) [0.3; 1.1]) to 16.4% (CI(95th) [14.5; 18.3]) of adults and 10.5% (CI(95th) [8.6; 12.4]) to 66.2% (CI(95th) [63.3; 69.1]) of children were higher than the ADI.

  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. Formation of genotoxic nitroPAH compounds in fish exposed to ambient nitrite and PAH

    Digital Repository Service at National Institute of Oceanography (India)

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

    medium were 1 mg l-1 and 1 ? M, respectively. Control fish (n=6) were exposed to equivalent concentrations of nitrite or phenanthrene only. In another set of experiments, O. mossambicus (n=6) were administered a single intra...-peritoneal injection (1 ? g g-1) of phenanthrene dissolved in sunflower oil (100 ? l) and exposed to dissolved nitrite (1 ? M) for 6 days as before. An equal number of control fish received equivalent amounts of phenanthrene without being exposed to nitrite. 4...

  5. Molecular Characterization of Lactobacillus plantarum DMDL 9010, a Strain with Efficient Nitrite Degradation Capacity

    OpenAIRE

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

    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 oth...

  6. Modulation by copper of the products of nitrite respiration in Pseudomonas perfectomarinus.

    OpenAIRE

    Matsubara, T; Frunzke, K; Zumft, W G

    1982-01-01

    A synthetic growth medium was purified with the chelator 1,5-diphenylthiocarbazone to study the effects of copper on partial reactions and product formation of nitrite respiration in Pseudomonas perfectomarinus. This organism grew anaerobically in a copper-deficient medium with nitrate or nitrite as the terminal electron acceptor. Copper-deficient cells had high activity for reduction of nitrate, nitrite, and nitric oxide, but little activity for nitrous oxide reduction. High rates of nitrous...

  7. Nitrite and Nitrate Concentrations and Metabolism in Breast Milk, Infant Formula, and Parenteral Nutrition

    OpenAIRE

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

    2013-01-01

    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...

  8. 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

  9. Blood Pressure-Lowering Effect of Orally Ingested Nitrite Is Abolished by a Proton Pump Inhibitor.

    Science.gov (United States)

    Montenegro, Marcelo F; Sundqvist, Michaela L; Larsen, Filip J; Zhuge, Zhengbing; Carlström, Mattias; Weitzberg, Eddie; Lundberg, Jon O

    2017-01-01

    Inorganic nitrate and nitrite from dietary and endogenous sources are metabolized to NO and other bioactive nitrogen oxides that affect blood pressure. The mechanisms for nitrite bioactivation are unclear, but recent studies in rodents suggest that gastric acidity may influence the systemic effects of this anion. In a randomized, double-blind, placebo-controlled crossover study, we tested the effects of a proton pump inhibitor on the acute cardiovascular effects of nitrite. Fifteen healthy nonsmoking, normotensive subjects, aged 19 to 39 years, were pretreated with placebo or esomeprazole (3×40 mg) before ingesting sodium nitrite (0.3 mg kg(-1)), followed by blood pressure monitoring. Nitrite reduced systolic blood pressure by a maximum of 6±1.3 mm Hg when taken after placebo, whereas pretreatment with esomeprazole blunted this effect. Peak plasma nitrite, nitrate, and nitroso species levels after nitrite ingestion were similar in both interventions. In 8 healthy volunteers, we then infused increasing doses of sodium nitrite (1, 10, and 30 nmol kg(-1) min(-1)) intravenously. Interestingly, although plasma nitrite peaked at similar levels as with orally ingested nitrite (≈1.8 µmol/L), no changes in blood pressure were observed. In rodents, esomeprazole did not affect the blood pressure response to the NO donor, DEA NONOate, or vascular relaxation to nitroprusside and acetylcholine, demonstrating an intact downstream NO-signaling pathway. We conclude that the acute blood pressure-lowering effect of nitrite requires an acidic gastric environment. Future studies will reveal if the cardiovascular complications associated with the use of proton pump inhibitors are linked to interference with the nitrate-nitrite-NO pathway. © 2016 American Heart Association, Inc.

  10. 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.

  11. The effect of pH and nitrite concentration on the antimicrobial impact of celery juice concentrate compared with conventional sodium nitrite on Listeria monocytogenes.

    Science.gov (United States)

    Horsch, A M; Sebranek, J G; Dickson, J S; Niebuhr, S E; Larson, E M; Lavieri, N A; Ruther, B L; Wilson, L A

    2014-01-01

    The objectives of this study were to evaluate the impact of pH and nitrite from celery juice concentrate (CJ) on the growth of Listeria monocytogenes in broth and on ham slices, and to evaluate the impact of pH and nitrite from CJ on quality attributes of the ham. The pH of both broth and ham were increased by the addition of CJ. The CJ was less effective than conventional nitrite at 100 mg/kg nitrite in broth, but in ham, the CJ treatments at both 100 and 200 mg/kg resulted in growth of L. monocytogenes (p>0.05) similar to that of the conventional nitrite at the same concentrations. Reducing the pH of CJ before addition to the ham had greater impact on L. monocytogenes growth at 200 mg/kg nitrite than at 100 mg/kg. Celery juice concentrate may increase meat product pH which could have implications for the antimicrobial impact of nitrite in some products. © 2013.

  12. METHOD FOR NITRATE DETERMINATION IN WATER IN THE PRESENCE OF NITRITE

    Directory of Open Access Journals (Sweden)

    Maria Sandu

    2014-12-01

    Full Text Available The study relates to determination of nitrate in presence of nitrite in water and can be used in the quality monitoring of natural water (surface and groundwater, drinking water, water from fish farms and public aquaria where autonomous filters is used. The nature and quantity of reagents used have insignificant impact on natural waters and sewages. According to the investigation, the method includes the removal of nitrite from the solution/water with sulfaminic acid, the nitrate ion reduction to nitrite using a reducing mixture that contains Na2SO4 and zinc dust in ratio of 100:5 and determining the nitrite with the Griess reagent.

  13. 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.

  14. 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 (pcuring process of meat without addition of other nitrite sources.

  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. Aqueous Two-Phase Extraction and Spectrophotometric Determination of Nitrite in Food Samples

    Science.gov (United States)

    Liu, Y.; Cai, Q.; Ma, W.

    2015-07-01

    An ethanol-(NH 4 ) 2 SO 4 aqueous two-phase system has been applied to the extraction and spectrophotometric determination of nitrite. The complex formed by nitrite and methyl orange was extracted to the upper ethanol phase and was measured at 432 nm. The concentration of nitrite varies linearly with the absorbance over the range of ~0.5-6.0 mg/l. The proposed method has been applied to the determination of nitrite in food samples. The analytical results obtained by this method and the naphthyl ethylenediamine spectrophotometric method were in good agreement.

  17. Sodium nitrite blocks the activity of aminoglycosides against Pseudomonas aeruginosa biofilms.

    Science.gov (United States)

    Zemke, Anna C; Gladwin, Mark T; Bomberger, Jennifer M

    2015-01-01

    Sodium nitrite has broad antimicrobial activity at pH 6.5, including the ability to prevent biofilm growth by Pseudomonas aeruginosa on the surfaces of airway epithelial cells. Because of its antimicrobial activity, nitrite is being investigated as an inhaled agent for chronic P. aeruginosa airway infections in cystic fibrosis patients. However, the interaction between nitrite and commonly used aminoglycosides is unknown. This paper investigates the interaction between nitrite and tobramycin in liquid culture, abiotic biofilms, and a biotic biofilm model simulating the conditions in the cystic fibrosis airway. The addition of nitrite prevented killing by aminoglycosides in liquid culture, with dose dependence between 1.5 and 15 mM. The effect was not blocked by the nitric oxide scavenger CPTIO or dependent on efflux pump activity. Nitrite shifted the biofilm minimal bactericidal concentration (MBC-biofilm) from 256 μg/ml to >1,024 μg/ml in an abiotic biofilm model. In a biotic biofilm model, the addition of 50 mM nitrite decreased the antibiofilm activity of tobramycin by up to 1.2 log. Respiratory chain inhibition recapitulated the inhibition of aminoglycoside activity by nitrite, suggesting a potential mechanism of inhibition of energy-dependent aminoglycoside uptake. In summary, sodium nitrite induces resistance to both gentamicin and tobramycin in P. aeruginosa grown in liquid culture, as an abiotic biofilm, or as a biotic biofilm. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  18. 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”.

  19. Nitrate and nitrite uptake and reduction by intact sunflower plants.

    Science.gov (United States)

    Agüera, E; de la Haba, P; Fontes, A G; Maldonado, J M

    1990-08-01

    Nitrogen-starved sunflower plants (Helianthus annuus L. cv. Peredovic) cannot absorb NO 3 (-) or NO 2 (-) upon initial exposure to these anions. Ability of the plants to take up NO 3 (-) and NO 2 (-) at high rates from the beginning was induced by a pretreatment with NO 3 (-) . Nitrite also acted as inducer of the NO 2 (-) -uptake system. The presence of cycloheximide during NO 3 (-) -pretreatment prevented the subsequent uptake of NO 3 (-) and NO 2 (-) , indicating that both uptake systems are synthesized de novo when plants are exposed to NO 3 (-) . Cycloheximide also suppressed nitrate-reductase (EC 1.6.6.1) and nitrite-reductase (EC 1.7.7.1) activities in the roots. The sulfhydryl-group reagent N-ethylmaleimide greatly inhibited the uptake of NO 3 (-) and NO 2 (-) . Likewise, N-ethylmaleimide promoted in vivo the inactivation of nitrate reductase without affecting nitrite-reductase activity. Rates of NO 3 (-) and NO 2 (-) uptake as a function of external anion concentration exhibited saturation kinetics. The calculated Km values for NO 3 (-) and NO 2 (-) uptake were 45 and 23 μM, respectively. Rates of NO 3 (-) uptake were four to six times higher than NO 3 (-) -reduction rates in roots. In contrast, NO 2 (-) -uptake rates, found to be very similar to NO 3 (-) -uptake rates, were much lower (about 30 times) than NO 2 (-) -reduction rates. Removal of oxygen from the external solution drastically suppressed NO 3 (-) and NO 2 (-) uptake without affecting their reduction. Uptake and reduction were also differentially affected by pH. The results demonstrate that uptake of NO 3 (-) and NO 2 (-) into sunflower plants is mediated by energy-dependent inducible-transport systems distinguishable from the respective enzymatic reducing systems.

  20. 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.

  1. Inhibitory effects of nitrite on the reactions of bovine carbonic anhydrase II with CO2 and bicarbonate consistent with zinc-bound nitrite.

    Science.gov (United States)

    Nielsen, Per M; Fago, Angela

    2015-08-01

    Carbonic anhydrase (CA) is a zinc enzyme that catalyzes hydration of carbon dioxide (CO2) and dehydration of bicarbonate in red blood cells, thus facilitating CO2 transport and excretion. Bovine CA II may also react with nitrite to generate nitric oxide, although nitrite is a known inhibitor of the CO2 hydration reaction. To address the potential in vivo interference of these reactions and the nature of nitrite binding to the enzyme, we here investigate the inhibitory effect of 10-30 mM nitrite on Michaelis-Menten kinetics of CO2 hydration and bicarbonate dehydration by stopped-flow spectroscopy. Our data show that nitrite significantly affects the apparent dissociation constant KM for CO2 (11 mM) and bicarbonate (221 mM), and the turnover number kcat for the CO2 hydration (1.467 × 10(6) s(-1)) but not for the bicarbonate dehydration (7.927 × 10(5) s(-1)). These effects demonstrate mixed and competitive inhibition for the reaction with CO2 and bicarbonate, respectively, and are consistent with nitrite binding to the active site zinc. The high apparent dissociation constant found here for CO2, bicarbonate and nitrite (16-120 mM) are all overall consistent with published data and reveal a large capacity of free enzyme available for binding each of the three substrates at their in vivo levels, with little or no significant interference among reactions. The low affinity of the enzyme for nitrite suggests that the in vivo interaction between red blood cell CA II and nitrite requires compartmentalization at the anion exchanger protein of the red cell membrane to be physiologically relevant. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Substitutions in Calcium Aluminates and Calcium Aluminoferrites.

    Science.gov (United States)

    ALUMINUM COMPOUNDS, *CEMENTS, * CALCIUM COMPOUNDS, * FERRITES , *SCIENTIFIC RESEARCH, INFRARED SPECTROSCOPY, X RAY DIFFRACTION, CHEMICAL COMPOSITION, SUBSTITUTES, CHEMICAL ANALYSIS, ALKALI METAL COMPOUNDS.

  3. 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.

  4. Nitrogen Removal over Nitrite by Aeration Control in Aerobic Granular Sludge Sequencing Batch Reactors

    Directory of Open Access Journals (Sweden)

    Samuel Lochmatter

    2014-07-01

    Full Text Available This study investigated the potential of aeration control for the achievement of N-removal over nitrite with aerobic granular sludge in sequencing batch reactors. N-removal over nitrite requires less COD, which is particularly interesting if COD is the limiting parameter for nutrient removal. The nutrient removal performances for COD, N and P have been analyzed as well as the concentration of nitrite-oxidizing bacteria in the granular sludge. Aeration phase length control combined with intermittent aeration or alternate high-low DO, has proven to be an efficient way to reduce the nitrite-oxidizing bacteria population and hence achieve N-removal over nitrite. N-removal efficiencies of up to 95% were achieved for an influent wastewater with COD:N:P ratios of 20:2.5:1. The total N-removal rate was 0.18 kgN·m−3·d−1. With N-removal over nitrate the N-removal was only 74%. At 20 °C, the nitrite-oxidizing bacteria concentration decreased by over 95% in 60 days and it was possible to switch from N-removal over nitrite to N-removal over nitrate and back again. At 15 °C, the nitrite-oxidizing bacteria concentration decreased too but less, and nitrite oxidation could not be completely suppressed. However, the combination of aeration phase length control and high-low DO was also at 15 °C successful to maintain the nitrite pathway despite the fact that the maximum growth rate of nitrite-oxidizing bacteria at temperatures below 20 °C is in general higher than the one of ammonium-oxidizing bacteria.

  5. The role of inorganic nitrate and nitrite in CVD.

    Science.gov (United States)

    Jackson, Jacklyn; Patterson, Amanda J; MacDonald-Wicks, Lesley; McEvoy, Mark

    2017-12-01

    CVD is the leading cause of death worldwide, a consequence of mostly poor lifestyle and dietary behaviours. Although whole fruit and vegetable consumption has been consistently shown to reduce CVD risk, the exact protective constituents of these foods are yet to be clearly identified. A recent and biologically plausible hypothesis supporting the cardioprotective effects of vegetables has been linked to their inorganic nitrate content. Approximately 60-80 % inorganic nitrate exposure in the human diet is contributed by vegetable consumption. Although inorganic nitrate is a relatively stable molecule, under specific conditions it can be metabolised in the body to produce NO via the newly discovered nitrate-nitrite-NO pathway. NO is a major signalling molecule in the human body, and has a key role in maintaining vascular tone, smooth muscle cell proliferation, platelet activity and inflammation. Currently, there is accumulating evidence demonstrating that inorganic nitrate can lead to lower blood pressure and improved vascular compliance in humans. The aim of this review is to present an informative, balanced and critical review of the current evidence investigating the role of inorganic nitrate and nitrite in the development, prevention and/or treatment of CVD. Although there is evidence supporting short-term inorganic nitrate intakes for reduced blood pressure, there is a severe lack of research examining the role of long-term nitrate intakes in the treatment and/or prevention of hard CVD outcomes, such as myocardial infarction and cardiovascular mortality. Epidemiological evidence is needed in this field to justify continued research efforts.

  6. 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

    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...... 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...

  7. 75 FR 29534 - Inorganic Nitrates-Nitrite, Carbon and Carbon Dioxide, and Sulfur Registration Review; Draft...

    Science.gov (United States)

    2010-05-26

    ...] [FR Doc No: 2010-12591] ENVIRONMENTAL PROTECTION AGENCY [EPA-HQ-OPP-2010-0434; FRL-8826-6] Inorganic... ecological risk assessment for the registration review of inorganic nitrates - nitrites, carbon and carbon... inorganic nitrates- nitrites, carbon and carbon dioxide uses, as well as gas cartridge uses of sulfur. The...

  8. Toxic Effect Of Azo Dyes On Nitrite-N Utilization By Nitrobacter ...

    African Journals Online (AJOL)

    The toxicity of five azo dyes (toxicants) on Nitrobacter was investigated. The index for toxicity was inhibition of rate of nitrite-N utilization. The rate of nitrite-N utilization decreased with increase in concentration of each toxicant at specific exposure time. However, stimulation of utilization was obtained at low concentrations ...

  9. Nitrite in processed meat products in Khartoum, Sudan and dietary intake

    NARCIS (Netherlands)

    Adam, Aziza Hussein Bakheit; Mustafa, Nazik Eltayeb Musa; Rietjens, Ivonne M.C.M.

    2017-01-01

    Nitrite intake from locally processed meat in Khartoum, Sudan was estimated and compared to established safety levels. For this purpose, 90 locally processed meat samples were collected randomly from retail outlets and analysed for nitrite levels according to the British standard 1992 protocol

  10. 77 FR 71006 - Sodium Nitrite Injection and Sodium Thiosulfate Injection Drug Products Labeled for the Treatment...

    Science.gov (United States)

    2012-11-28

    ... HUMAN SERVICES Food and Drug Administration [Docket No. FDA-2012-N-1134 Sodium Nitrite Injection and Sodium Thiosulfate Injection Drug Products Labeled for the Treatment of Cyanide Poisoning; Enforcement... products containing sodium nitrite labeled for the treatment of cyanide poisoning and unapproved injectable...

  11. Citrus co-products as technological strategy to reduce residual nitrite content in meat products.

    Science.gov (United States)

    Viuda-Martos, M; Fernández-López, J; Sayas-Barbera, E; Sendra, E; Navarro, C; Pérez-Alvarez, J A

    2009-10-01

    Sodium or potassium nitrite is widely used as a curing agent in cured meat products because it inhibits outgrowth and neurotoxin formation by Clostridium botulinum, delays the development of oxidative rancidity, develops the characteristic flavor of cured meats, and reacts with myoglobin and stabilizes the red meat color. As soon as nitrite is added in the meat formulation, it starts to disappear and the nitrite that has not reacted with myoglobin and it is available corresponds to residual nitrite level. Health concerns relating to the use of nitrates and nitrites in cured meats (cooked and dry cured) trend toward decreased usage to alleviate the potential risk to the consumers from formation of carcinogenic compounds. Recently, some new ingredients principally agro-industrial co-products in general and those from the citrus industry in particular (albedo [with different treatments], dietetic fiber obtained from the whole co-product, and washing water used in the process to obtain the dietetic fiber) are seen as good sources of bio-compounds that may help to reduce the residual nitrite level in meat products. From these co-products, citrus fiber shows the highest potential to reduce the residual nitrite level, followed by the albedo and finally the washing water. The aim of this article is to describe the latest advances concerning the use of citrus co-products in meat products as a potential ingredient to reduce the nitrite level.

  12. Dietary nitrite attenuates oxidative stress and activates antioxidant genes in rat heart during hypobaric hypoxia.

    Science.gov (United States)

    Singh, Manjulata; Arya, Aditya; Kumar, Rajesh; Bhargava, Kalpana; Sethy, Niroj Kumar

    2012-01-01

    The nitrite anion represents the circulatory and tissue storage form of nitric oxide (NO) and a signaling molecule, capable of conferring cardioprotection and many other health benefits. However, molecular mechanisms for observed cardioprotective properties of nitrite remain largely unknown. We have evaluated the NO-like bioactivity and cardioprotective efficacies of sodium nitrite supplemented in drinking water in rats exposed to short-term chronic hypobaric hypoxia. We observed that, nitrite significantly attenuates hypoxia-induced oxidative stress, modulates HIF-1α stability and promotes NO-cGMP signaling in hypoxic heart. To elucidate potential downstream targets of nitrite during hypoxia, we performed a microarray analysis of nitrite supplemented hypoxic hearts and compared with both hypoxic and nitrite supplemented normoxic hearts respectively. The analysis revealed a significant increase in the expression of many antioxidant genes, transcription factors and cardioprotective signaling pathways which was subsequently confirmed by qRT-PCR and Western blotting. Conversely, hypoxia exposure increased oxidative stress, activated inflammatory cytokines, downregulated ion channels and altered expression of both pro- and anti-oxidant genes. Our results illustrate the physiological function of nitrite as an eNOS-independent source of NO in heart profoundly modulating the oxidative status and cardiac transcriptome during hypoxia. Copyright © 2011 Elsevier Inc. All rights reserved.

  13. Voltammetry and In Situ Scanning Tunneling Microscopy of Cytochrome c Nitrite Reductase on Au(111)-Electrodes

    DEFF Research Database (Denmark)

    Gwyer, James; Zhang, Jingdong; Butt, Julea

    2006-01-01

    Escherichia coli cytochrome c nitrite reductase (NrfA) catalyzes the six-electron reduction of nitrite to perform an important role in the biogeochemical cycling of nitrogen. Here we describe NrfA adsorption on single-crystal Au(111) electrodes as an electrocatalytically active film in which the ...

  14. 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 ...

  15. Nitrite enhances liver graft protection against cold ischemia reperfusion injury through a NOS independent pathway.

    Science.gov (United States)

    Cherif-Sayadi, Amani; Hadj Ayed-Tka, Kaouther; Zaouali, Mohamed Amine; Bejaoui, Mohamed; Hadj-Abdallah, Najet; Bouhlel, Ahlem; Ben Abdennebi, Hassen

    2017-12-01

    Nitrite has been found to protect liver graft from cold preservation injury. However, the cell signaling pathway involved in this protection remains unclear. Here, we attempt to clarify if the NOS pathway by using the NOS inhibitor, L-NAME (L-N(G)-Nitroarginine methyl ester). Rat livers were conserved for 24 h at 4°C in (IGL-1) solution enriched or not with nitrite at 50 nM. In a third group, rats were pretreated with 50 mg/kg of L-NAME before their liver procurement and preservation in IGL-1 supplemented with nitrite (50 nM) and L-NAME (1 mM). After 24 h of cold storage, rat livers were ex-vivo perfused at 37°C during 2 h. Control livers were perfused without cold storage. Nitrite effectively protected the rat liver grafts from the onset of cold I/R injury. L-NAME treatment did not abolish the beneficial effects of nitrite. Liver damage, protein oxidation and lipid peroxidation remained at low levels in both nitrite-treated groups when compared to IGL-1 group. Antioxidant enzyme activities and functional parameters were unchanged after NOS inhibition. Despite NOS inhibition by L-NAME, nitrite can still provide hepatic protection during cold I/R preservation. This suggests that nitrite acts through a NOS-independent pathway.

  16. 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.

    the effect of a natural stress such as the presence of nitrite in water on the xenobiotic metabolism in fish, the euryhaline cichlid Oreochromis mossambicus was exposed for up to 9 days to environmentally relevant concentrations of water-borne nitrite...

  17. Effects of different cooking methods and temperatures on residual nitrite content in sausage

    Directory of Open Access Journals (Sweden)

    MGh.Soleimani

    2015-10-01

    Full Text Available Background: Presence of nitrites in meat products is important because they combine with secondary amines and produce nitrosamine carcinogen. Objective: The aim of this study was to determine the effects of different cooking methods and temperatures on residual nitrite content in sausage. Methods: This experimental study was conducted in the Food and Drug Laboratory of Qazvin University of Medical Sciences in 2014. Sausage samples containing 90% meat that were produced under identical conditions in a factory in Qazvin were transferred to the laboratory under suitable conditions and their residual nitrite contents were measured. The residual nitrite content was remeasured three times after using different cooking methods (frying, grilling, and cooking in microwave oven at different temperatures and durations in 39 experiments. Data were analyzed using one-way ANOVA. Findings: Before cooking, the residual nitrite content was 33.57 mg/kg in the sausage samples and reached to 26.46 mg/kg after frying at 120º C for 5 minutes. Mean residual nitrite content was significantly different at other temperatures and cooking durations. The mean residual nitrite content reached to 1.42 and 0 after frying at 220º C for 5 and 10 minutes, respectively. Conclusion: With regards to the results, the greater the temperature and the duration of cooking, the more the reduction in residual nitrite content of the final product.

  18. 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 beverages.

  19. Protein film voltammetry of copper-containing nitrite reductase reveals reversible inactivation

    NARCIS (Netherlands)

    Wijma, Hein J.; Jeuken, Lars J. C.; Verbeet, Martin Ph.; Armstrong, Fraser A.; Canters, Gerard W.

    2007-01-01

    The Cu-containing nitrite reductase from Alcaligenes faecalis S-6 catalyzes the one-electron reduction of nitrite to nitric oxide (NO). Electrons enter the enzyme at the so-called type-1 Cu site and are then transferred internally to the catalytic type-2 Cu site. Protein film voltammetry experiments

  20. 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 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.

  1. 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...

  2. 21 CFR 250.100 - Amyl nitrite inhalant as a prescription drug for human use.

    Science.gov (United States)

    2010-04-01

    ... August 25, 1967 (32 FR 12404), the Commissioner of Food and Drugs received reports of the abuse of this... Board, that amyl nitrite inhalant is a drug with a potentiality for harmful effect and that it should be... 21 Food and Drugs 4 2010-04-01 2010-04-01 false Amyl nitrite inhalant as a prescription drug for...

  3. 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

  4. Calcium channel blocker overdose

    Science.gov (United States)

    ... 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 to ...

  5. 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 ...

  6. 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.

  7. 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

    analysis. Furthermore, the effect of varying air load and water exchange was investigated. Absence of NOB in many filters was explained by the inhibitory effect of Free Ammonia (FA). When first established, NOB induced a self-perpetuating effect through oxidation of nitrite which allowed increased AOB......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...... 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...

  8. Spectrophotometric and kinetic study of nitrite and formate oxidation in Nitrobacter winogradskyi.

    Science.gov (United States)

    Van Gool, A; Laudelout, H

    1967-01-01

    The reduction levels of cytochrome c and a(1) in intact Nitrobacter cells and cell-free extracts, during and after nitrite or formate oxidation, were examined in combination with the amperometric measurement of oxygen uptake. Quite different reduction patterns were observed when comparing nitrite oxidation by intact cells and cell-free extracts. An inverse relationship was observed between the rate of electron flow and the steady-state reduction level of cytochrome a(1). Parallel observations on nitrite oxidation, by use of formate and reduced nicotinamide adenine dinucleotide as electron donors, showed the influence of the high oxidation-reduction potential of the nitrite-nitrate system on cytochrome reduction. A value for the apparent activation energy of the overall nitrite oxidation process, amounting to 15 kcal, was found in a study of the temperature dependence of cytochrome reduction.

  9. 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

  10. 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.

  11. 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.

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

    Science.gov (United States)

    Pereira, Cassilda; Ferreira, Nuno R.; Rocha, Bárbara S.; Barbosa, Rui M.; Laranjinha, João

    2013-01-01

    The reversible redox conversion of nitrite and nitric oxide (•NO) in a physiological setting is now widely accepted. Nitrite has long been identified as a stable intermediate of •NO oxidation but several lines of evidence support the reduction of nitrite to nitric oxide in vivo. In the gut, this notion implies that nitrate from dietary sources fuels the longstanding production of nitrite in the oral cavity followed by univalent reduction to •NO in the stomach. Once formed, •NO boosts a network of reactions, including the production of higher nitrogen oxides that may have a physiological impact via the post-translational modification of proteins and lipids. Dietary compounds, such as polyphenols, and different prandial states (secreting specific gastric mediators) modulate the outcome of these reactions. The gut has unusual characteristics that modulate nitrite and •NO redox interplay: (1) wide range of pH (neutral vs acidic) and oxygen tension (c.a. 70 Torr in the stomach and nearly anoxic in the colon), (2) variable lumen content and (3) highly developed enteric nervous system (sensitive to •NO and dietary compounds, such as glutamate). The redox interplay of nitrite and •NO might also participate in the regulation of brain homeostasis upon neuronal glutamatergic stimulation in a process facilitated by ascorbate and a localized and transient decrease of oxygen tension. In a way reminiscent of that occurring in the stomach, a nitrite/•NO/ascorbate redox interplay in the brain at glutamatergic synapses, contributing to local •NO increase, may impact on •NO-mediated process. 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. PMID:24024161

  13. Nitrite modulates bacterial antibiotic susceptibility and biofilm formation in association with airway epithelial cells.

    Science.gov (United States)

    Zemke, Anna C; Shiva, Sruti; Burns, Jane L; Moskowitz, Samuel M; Pilewski, Joseph M; Gladwin, Mark T; Bomberger, Jennifer M

    2014-12-01

    Pseudomonas aeruginosa is the major pathogenic bacteria in cystic fibrosis and other forms of bronchiectasis. Growth in antibiotic-resistant biofilms contributes to the virulence of this organism. Sodium nitrite has antimicrobial properties and has been tolerated as a nebulized compound at high concentrations in human subjects with pulmonary hypertension; however, its effects have not been evaluated on biotic biofilms or in combination with other clinically useful antibiotics. We grew P. aeruginosa on the apical surface of primary human airway epithelial cells to test the efficacy of sodium nitrite against biotic biofilms. Nitrite alone prevented 99% of biofilm growth. We then identified significant cooperative interactions between nitrite and polymyxins. For P. aeruginosa growing on primary CF airway cells, combining nitrite and colistimethate resulted in an additional log of bacterial inhibition compared to treating with either agent alone. Nitrite and colistimethate additively inhibited oxygen consumption by P. aeruginosa. Surprisingly, whereas the antimicrobial effects of nitrite in planktonic, aerated cultures are nitric oxide (NO) dependent, antimicrobial effects under other growth conditions are not. The inhibitory effect of nitrite on bacterial oxygen consumption and biofilm growth did not require NO as an intermediate as chemically scavenging NO did not block growth inhibition. These data suggest an NO-radical independent nitrosative or oxidative inhibition of respiration. The combination of nebulized sodium nitrite and colistimethate may provide a novel therapy for chronic P. aeruginosa airway infections, because sodium nitrite, unlike other antibiotic respiratory chain "poisons," can be safely nebulized at high concentration in humans. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Remediation of nitrite contamination in ground and surface waters using aquatic macrophytes.

    Science.gov (United States)

    Rawat, S K; Singh, R K; Singh, Rana P

    2012-01-01

    The study was carried out to determine the seasonal variation of nitrite levels in drinking and surface waters of urban, peri-urban and rural areas of Lucknow, during 2007-2008, and to evaluate the nitrite removal and accumulation potential of certain native aquatic macrophytes. Most of the drinking and surface water samples were collected from urbanized region of the city. All drinking water samples detected, showed higher nitrite level in winter, when compared with that in summer and rainy seasons. However, in drinking water samples nitrite level was below the permissible limit i.e. 3.29 mg l(-1) NO2. The surface water showed more than 3 fold higher levels of nitrite over the permissible level i.e. 0.06 mg l(-1), and the level was higher during rainy season than in summer and winterseasons. Eight macrophytes viz. Peltandra virginica, Utricularia vulgaris, Eichhomia crassipes, Trapa natans, Mimulus glabratus, Marsilea quadrifolia, Pistia stratiotes and Polygonum persicaria were studied for phytoremediation potential of nitrite from the water under simulated laboratory conditions. The gradual diminution in the level of nitrite in the water and simultaneously it's increase in the plant tissues was recorded at 5th, 10th and 15th d after plant culture. All the plants selected, removed nitrite from water but Polygonum persicaria, Mimulus glabratus, Trapa natans and Pistia stratiotes were found more efficient and removed nitrite upto 60.91, 58.09, 60.97 and 72.28%, respectively. Observations revealed that Pistia stratiotes can be used forthe effective removal of nitrite from the contaminated water.

  15. 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

  16. Effects of pulse duration and post-exposure period on the nitrite toxicity to a freshwater amphipod

    NARCIS (Netherlands)

    Alonso, A.; Camargo, J.A.

    2009-01-01

    This research assesses the effects of nitrite pulses and post-exposure periods after nitrite exposures on the survival of the freshwater amphipod Eulimnogammarus toletanus. A toxicity bioassay was performed using three different nitrite concentrations (0.5, 5.0 and 10.0 mg/L NO2-N), four pulse

  17. 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.

  18. The effects of lactate on nitrosylmyoglobin formation from nitrite and metmyoglobin in a cured meat system.

    Science.gov (United States)

    McClure, Brooke N; Sebranek, Joseph G; Kim, Yuan H; Sullivan, Gary A

    2011-12-01

    Two experiments were conducted to determine the effects of lactate on nitrite during meat curing. In the first experiment, using a model system, eight reaction components including nitrite and lactate, were used to assess the effect of each component on metmyoglobin reducing activity by excluding one component at a time. Excluding lactate, nicotinamide adenine dinucleotide (NAD), l-lactate dehydrogenase (LDH) or phenazine methosulfate (PMS) resulted in no reducing activity. A second experiment, utilising a meat mixture, investigated the effects of lactate (0%, 2%, 4% or 6%), nitrite (0 or 156ppm), and packaging (oxygen-permeable or vacuum) on residual nitrite, meat colour and pH. Addition of lactate reduced residual nitrite in the meat mixtures. Both experiments support the hypothesis that lactate generates NADH which then reduces metmyoglobin to deoxymyoglobin. The resulting greater concentration of reduced myoglobin subsequently reacted with nitrite to produce more nitric oxide, reducing nitrite concentration and accelerating curing reactions. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. The nitritation performance of biofilm reactor for treating domestic wastewater under high dissolved oxygen.

    Science.gov (United States)

    Zheng, Zhaoming; Li, Zebing; Ma, Jing; Du, Jia; Chen, Guanghui; Bian, Wei; Li, Jun; Zhao, Baihang

    2016-04-01

    The objective of this study was to investigate the nitritation performance in a biofilm reactor for treating domestic wastewater. The reactor was operated in continuous feed mode from phases 1 to 3. The dissolved oxygen (DO) was controlled at 3.5-7 mg/L throughout the experiment. The biofilm reactor showed excellent nitritation performance after the inoculation of nitrifying sludge, with the hydraulic retention time being reduced from 24 to 7 hr. Above 90% nitrite accumulation ratio (NAR) was maintained in phase 1. Afterwards, nitratation occurred with the low NH4(+)-N concentration in the reactor. The improvement of NH4(+)-N concentration to 20-35 mg/L had a limited effect on the recovery of nitritation. However, nitritation recovered rapidly when sequencing batch feed mode was adopted in phase 4, with the effluent NH4(+)-N concentration above 7 mg/L. The improvement of ammonia oxidizing bacteria (AOB) activity and the combined inhibition effect of free ammonia (FA) and free nitrous acid (FNA) on the nitrite oxidizing bacteria (NOB) were two key factors for the rapid recovery of nitritation. Sludge activity was obtained in batch tests. The results of batch tests had a good relationship with the long term operation performance of the biofilm reactor. Copyright © 2015. Published by Elsevier B.V.

  20. Cod liver oil in sodium nitrite induced hepatic injury: does it have a potential protective effect?

    Science.gov (United States)

    Sherif, I O; Al-Gayyar, M M

    2015-01-01

    Exposure to sodium nitrites, a food additive, at high levels has been reported to produce reactive nitrogen and oxygen species that cause dysregulation of inflammatory responses and tissue injury. In this work, we examined the impact of dietary cod liver oil on sodium nitrite-induced inflammation in rats. Thirty-two adult male Sprague-Dawely rats were treated with 80 mg/kg sodium nitrite in presence/absence of 5 ml/kg cod liver oil. Liver sections were stained with hematoxylin/eosin. We measured hepatic tumor necrosis factor (TNF)-α, interleukin-1 beta (IL)-1β, C-reactive protein (CRP), transforming growth factor (TGF)-β1, and caspase-3. Cod liver oil reduced sodium nitrite-induced hepatocyte damage. In addition, cod liver oil results in reduction of hepatic TNF-α, IL-1β, CRP, TGF-β1, and caspase-3 when compared with the sodium nitrite group. Cod liver oil ameliorates sodium nitrite-induced hepatic injury via multiple mechanisms including blocking sodium nitrite-induced elevation of inflammatory cytokines, fibrosis mediators, and apoptosis markers.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Measurement of nitrite and nitrate in saliva of children with different caries activity.

    Science.gov (United States)

    Ghasempour, Maryam; Qujeq, Durdi; Rabiee, Maryam; Hamzeh, Mahtab

    2014-09-01

    Recently, there has been growing interest in the role of salivary nitrate and nitrite in caries protection. Nitrate is a natural compound found in fruits and vegetables and when secreted in saliva, is reduced to nitrite through bacterial respiration and subsequently reduced to nitric oxide in acidic condition. Nitric oxide takes part in oral non-specific immune system and prevents bacterial growth. The aim of present study was to determine the concentration of nitrite and nitrate in saliva of children with different caries activity. Ninety three children, 4 to 6 years old, enrolled in this case-control study and were divided into 3 groups; 31 caries free children, 31 with 5 10. Unstimulated saliva was collected and stored in 4°C. Measurement of nitrate and nitrite concentration was performed using Griess reaction. Data were analyzed by T-test, Chi-square, ANOVA and multiple comparisons using SPSS 18. p < 0.05 was considered significant. Mean value of DFS in the first, second and third were 0, 7.12 and 12.61 respectively. Mean value of nitrite and nitrate in the third group was significantly higher than two others (p < 0.05), but the difference between first and second group was not significant. Increase in DFS was associated by increase in salivary nitrite and nitrate concentration. High concentration of nitrate and nitrite is not enough for caries prevention.

  6. 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; Blood, Arlin B

    2014-10-01

    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. Copyright © 2014 the American Physiological Society.

  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. Reactions of ferrous neuroglobin and cytoglobin with nitrite under anaerobic conditions

    DEFF Research Database (Denmark)

    Petersen, Morten Gjerning; Dewilde, Sylvia; Fago, Angela

    2008-01-01

    hexacoordinate globins from vertebrates expressed in brain and in a variety of tissues, respectively, also react with nitrite under anaerobic conditions. Using absorption spectroscopy, we find that ferrous neuroglobin and nitrite react with a second-order rate constant similar to that of myoglobin, whereas......Recent evidence suggests that the reaction of nitrite with deoxygenated hemoglobin and myoglobin contributes to the generation of nitric oxide and S-nitrosothiols in vivo under conditions of low oxygen availability. We have investigated whether ferrous neuroglobin and cytoglobin, the two...

  9. [Nitroglycerin and amyl nitrite action on common bile duct during operation for vesicular lithiasis (author's transl)].

    Science.gov (United States)

    Chelly, J; Tannières, M L; Tournay, D; Franchiset, F; Alexandre, J H; Passelecq, J

    1979-01-01

    Eight patients undergoing cholecystectomy received a single injection of nitroglycerin (0,9 mg) and 8 received amyl nitrite, during a cholangio-kinesimetry. The maximum fall in common bile duct pressure was similar in both group; 3.2 +/- 0.3 torr after nitroglycerin (NTG),3.8 +/- 0.6 torr after amyl nitrite (AN). NTG caused a more persistent lowering of pressure than AN; 614 +/- 42 seconds/343 +/- 27 seconds (p < 0.001). This study showed that it is possible to produce a relaxation of biliary tract muscle fibres with an injection of nitroglycerin and then replace amyl nitrite during anesthesia.

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

    Science.gov (United States)

    Singh Raman, R. K.; Siew, Wai Hoong

    2014-01-01

    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. PMID:28788276

  11. Post Chlorine gas exposure administration of nitrite prevents lung injury: effect of administration modality

    Science.gov (United States)

    Samal, Andrey A.; Honavar, Jaideep; Brandon, Angela; Bradley, Kelley M.; Doran, Stephen; Liu, Yanping; Dunaway, Chad; Steele, Chad; Postlethwait, Edward M.; Squadrito, Giuseppe L.; Fanucchi, Michelle V.; Matalon, Sadis; Patel, Rakesh P.

    2012-01-01

    Cl2 gas toxicity is complex and occurs during, and post exposure leading to acute lung injury (ALI) and reactive airway syndrome (RAS). Moreover, Cl2 exposure can occur in diverse situations encompassing mass casualty scenarios underscoring the need for post-exposure therapies that are efficacious and amenable to rapid and easy administration. In this study, we compared the efficacy of a single dose, post (30min) Cl2 exposure administration of nitrite (1mg/kg) via intraperitoneal (IP) or intramuscular (IM) injection in rats, to decrease ALI. Exposure of rats to Cl2 gas (400ppm, 30min) significantly increased ALI and caused RAS 6–24h post exposure as indexed by BAL sampling of lung surface protein, PMN and increased airway resistance and elastance prior to and post methacholine challenge. IP nitrite decreased Cl2 - dependent increases in BAL protein but not PMN. In contrast IM nitrite decreased BAL PMN levels without decreasing BAL protein in a xanthine oxidoreductase independent manner. Histological evaluation of airways 6h post exposure showed significant bronchial epithelium exfoliation and inflammatory injury in Cl2 exposed rats. Both IP and IM nitrite improved airway histology compared to Cl2 gas alone, but more coverage of the airway by cuboidal or columnar epithelium was observed with IM compared to IP nitrite. Airways were rendered more sensitive to methacholine induced resistance and elastance after Cl2 gas exposure. Interestingly, IM nitrite, but not IP nitrite, significantly decreased airway sensitivity to methacholine challenge. Further evaluation and comparison of IM and IP therapy showed a two-fold increase in circulating nitrite levels with the former, which was associated with reversal of post-Cl2 exposure dependent increases in circulating leukocytes. Halving the IM nitrite dose resulted in no effect in PMN accumulation but significant reduction of of BAL protein levels indicating distinct nitrite dose dependence for inhibition of Cl2 dependent

  12. Administration of nitrite after chlorine gas exposure prevents lung injury: effect of administration modality.

    Science.gov (United States)

    Samal, Andrey A; Honavar, Jaideep; Brandon, Angela; Bradley, Kelley M; Doran, Stephen; Liu, Yanping; Dunaway, Chad; Steele, Chad; Postlethwait, Edward M; Squadrito, Giuseppe L; Fanucchi, Michelle V; Matalon, Sadis; Patel, Rakesh P

    2012-10-01

    Cl(2) gas toxicity is complex and occurs during and after exposure, leading to acute lung injury (ALI) and reactive airway syndrome (RAS). Moreover, Cl(2) exposure can occur in diverse situations encompassing mass casualty scenarios, highlighting the need for postexposure therapies that are efficacious and amenable to rapid and easy administration. In this study, we assessed the efficacy of a single dose of nitrite (1 mg/kg) to decrease ALI when administered to rats via intraperitoneal (ip) or intramuscular (im) injection 30 min after Cl(2) exposure. Exposure of rats to Cl(2) gas (400 ppm, 30 min) significantly increased ALI and caused RAS 6-24h postexposure as indexed by BAL sampling of lung surface protein and polymorphonucleocytes (PMNs) and increased airway resistance and elastance before and after methacholine challenge. Intraperitoneal nitrite decreased Cl(2)-dependent increases in BAL protein but not PMNs. In contrast im nitrite decreased BAL PMN levels without decreasing BAL protein in a xanthine oxidoreductase-dependent manner. Histological evaluation of airways 6h postexposure showed significant bronchial epithelium exfoliation and inflammatory injury in Cl(2)-exposed rats. Both ip and im nitrite improved airway histology compared to Cl(2) gas alone, but more coverage of the airway by cuboidal or columnar epithelium was observed with im compared to ip nitrite. Airways were rendered more sensitive to methacholine-induced resistance and elastance after Cl(2) gas exposure. Interestingly, im nitrite, but not ip nitrite, significantly decreased airway sensitivity to methacholine challenge. Further evaluation and comparison of im and ip therapy showed a twofold increase in circulating nitrite levels with the former, which was associated with reversal of post-Cl(2) exposure-dependent increases in circulating leukocytes. Halving the im nitrite dose resulted in no effect in PMN accumulation but significant reduction of BAL protein levels, indicating a distinct

  13. 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.

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

    Science.gov (United States)

    Raman, R K Singh; Siew, Wai Hoong

    2014-12-05

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  16. 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.

  17. 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

  18. 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.

  19. Interaction of "Candidatus Accumulibacter" and nitrifying bacteria to achieve energy-efficient denitrifying phosphorus removal via nitrite pathway from sewage.

    Science.gov (United States)

    Zeng, Wei; Bai, Xinlong; Guo, Yu; Li, Ning; Peng, Yongzhen

    2017-10-01

    To achieve energy-efficient denitrifying phosphorus removal via nitrite pathway from sewage, interaction of "Candidatus Accumulibacter" and nitrifying bacteria was investigated in a continuous-flow process. When nitrite in returned sludge of secondary settler was above 13mg/L, nitrite inhibition on anaerobic P-release of poly-phosphate organisms (PAOs) occurred. Clades IIC and IID were dominant, reaching 3.1%-11.9% of total bacteria. Clade IIC was sensitive to nitrite. Under low concentration of nitrite (<8mg/L), clade IIC primarily contributed to anoxic P-uptake. Clade IID had a strong tolerance to nitrite exposure. At high nitrite level (above 16mg/L), anoxic P-uptake was mainly performed by clade IID due to its strong tolerance to nitrite exposure. Ammonia oxidizing bacteria (AOB), nitrite oxidizing bacteria (NOB) and Accumulibacter interacted through variations of nitrite accumulation. High AOB abundance coupled with inhibition of NOB favored denitrifying phosphorus removal by clade IID. All Accumulibacter lineages were sorted into four clades of Type II. The most dominant ppk1 gene homologs were affiliated with clade IID, accounting for 69% of ppk1 clone library, and thus played an important role in denitrifying phosphorus removal via nitrite pathway. Copyright © 2017. Published by Elsevier Inc.

  20. 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.

  1. 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

    . In this study, three suspended-growth oxygen-limited autotrophic nitrification-denitrification (OLAND) reactors with different inoculation and operation (mixing and aeration) conditions, designated reactors A, B, and C, were used. The test objectives were (i) to quantify the AerAOB and AnAOB abundance...... and the activity balance for the different aggregate sizes and (ii) to relate aggregate morphology, size distribution, and architecture putatively to the inoculation and operation of the three reactors. A nitrite accumulation rate ratio (NARR) was defined as the net aerobic nitrite production rate divided...... 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...

  2. Structured catalysts and reactors for three phase catalytic reactions: manipulating activity and selectivity in nitrite hydrogenation

    NARCIS (Netherlands)

    Brunet Espinosa, Roger

    2016-01-01

    This work aimed at fabricating structured catalytic reactors for fast multiphase reactions, namely, nitrite hydrogenation and H2O2 decomposition. These reactors allowed a better understanding of these reactions and an improvement in terms of catalytic activity and selectivity.

  3. 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.

  4. Low density lipoprotein inhibits accumulation of nitrites in murine brain endothelial cell cultures.

    Science.gov (United States)

    Bereta, M; Bereta, J; Cohen, S; Cohen, M C

    1992-07-15

    Endothelial cells produce nitric oxide which is considered to serve as a major source of endothelial derived relaxing factor activity. It has been demonstrated that activation of mouse brain endothelium by TNF-alpha and IFN-gamma led to accumulation of nitrite which is presumably formed by oxidation of nitric oxide. A number of studies suggest that reactive oxygen species produced by cytokine-activated cells are involved in the conversion of nitric oxide to nitrites and nitrates. We investigated whether low density lipoprotein (LDL), acting as a radical scavenger, is able to inhibit nitrite accumulation in mouse brain endothelial cell cultures and in a cell-free system in which sodium nitroprusside was used as a source of nitric oxide. A comparison of these two models indicates the active involvement of LDL in suppressing nitrite accumulation in murine endothelial cultures.

  5. 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

    In partial nitritation/anammox systems, aerobic and anoxic ammonium-oxidizing bacteria (AerAOB and AnAOB) remove ammonium from wastewater. In this process, large granular microbial aggregates enhance the performance, but little is known about this type of granulation so far. In this study.......e. the net aerobic nitrite production rate divided by the anoxic nitrite consumption rate, with all rates determined in aerobic and anoxic batch tests. The space occupied by extracellular polymeric substances (EPS) was calculated from transmission electron micrographs. All smallest aggregates were flocs...... 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...

  6. 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.

  7. EVALUASI PENCEMARAN NITRAT-NITRIT PADA AIR MINUM PDAM DI DKI JAKARTA

    Directory of Open Access Journals (Sweden)

    Sukar Sukar

    2012-09-01

    Full Text Available A survey on drinking water quality was conducted in 1990/1991 to evaluate the impact of organic matters particularly of nitrate-nitrite contamination in raw water. Water samples were taken from Water Supply Enterprices (WSE in Jakarta, i.e Pejompongan WSE and Pulogadung WSE. The results showed that the treatment efficiency of Pejompongan WSE to reduce nitrate and nitrite concentration was 5% and 82.1% respectively, and that of Pulogadung WSE were 50.0% and 63.2%. The concentration of nitrate in water the supply from Pejompongan WSE and Pulogadung WSE in general is in accordance with the water quality standard. The nitrite level in the water supply from Pejompongan also met the standard, while from Pulogadung did not. It has been observed that the nitrite concentration in water from Pejompongan distribution pipe is increasing with the distance from water treatment installation.

  8. 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

    Nitrospira are a diverse group of nitrite-oxidizing bacteria and among the environmentally most widespread nitrifiers. However, they remain scarcely studied and mostly uncultured. Based on genomic and experimental data from Nitrospira moscoviensis representing the ubiquitous Nitrospira lineage II...

  9. 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 (p<0.05). The enterobacteria Escherichia coli and Lactobacillus casei reduced the amount of these compounds present during in vitro human digestion. 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.

  10. 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.

    the impact of nitrite (NO2−) on the metabolism of polycyclic aromatic hydrocarbons (PAHs) in fish. In a laboratory experiment, exposure of euryhaline fish, Oreochromis mossambicus to industrial effluents containing PAHs in the presence of NO2− enhanced...

  11. Conversion of nitrite to nitric oxide at zinc via S-nitrosothiols.

    Science.gov (United States)

    Cardenas, Allan Jay P; Abelman, Rebecca; Warren, Timothy H

    2014-01-07

    Nitrite is an important reservoir of nitric oxide activity in the plasma and cells. Using a biomimetic model, we demonstrate the conversion of zinc-bound nitrite in the tris(pyrazolyl)borate complex (iPr2)TpZn(NO2) to the corresponding S-nitrosothiol RSNO and zinc thiolate (iPr2)TpZn-SR via reaction with thiols H-SR. Decomposition of the S-nitrosothiol formed releases nitric oxide gas.

  12. Nitrite-Templated Synthesis of Lanthanide-Containing [2]Rotaxanes for Anion Sensing**

    Science.gov (United States)

    Langton, Matthew J; Blackburn, Octavia A; Lang, Thomas; Faulkner, Stephen; Beer, Paul D

    2014-01-01

    The first anion-templated synthesis of a lanthanide-containing interlocked molecule is demonstrated by utilizing a nitrite anion to template initial pseudorotaxane formation. Subsequent stoppering of the interpenetrated assembly allows for the preparation of a lanthanide-functionalized [2]rotaxane in high yield. Following removal of the nitrite anion template, the europium [2]rotaxane host is demonstrated to recognize and sense fluoride selectively. PMID:24989322

  13. Nitrospira-like bacteria associated with nitrite oxidation in freshwater aquaria.

    Science.gov (United States)

    Hovanec, T A; Taylor, L T; Blakis, A; Delong, E F

    1998-01-01

    Oxidation of nitrite to nitrate in aquaria is typically attributed to bacteria belonging to the genus Nitrobacter which are members of the alpha subdivision of the class Proteobacteria. In order to identify bacteria responsible for nitrite oxidation in aquaria, clone libraries of rRNA genes were developed from biofilms of several freshwater aquaria. Analysis of the rDNA libraries, along with results from denaturing gradient gel electrophoresis (DGGE) on frequently sampled biofilms, indicated the presence of putative nitrite-oxidizing bacteria closely related to other members of the genus Nitrospira. Nucleic acid hybridization experiments with rRNA from biofilms of freshwater aquaria demonstrated that Nitrospira-like rRNA comprised nearly 5% of the rRNA extracted from the biofilms during the establishment of nitrification. Nitrite-oxidizing bacteria belonging to the alpha subdivision of the class Proteobacteria (e.g., Nitrobacter spp.) were not detected in these samples. Aquaria which received a commercial preparation containing Nitrobacter species did not show evidence of Nitrobacter growth and development but did develop substantial populations of Nitrospira-like species. Time series analysis of rDNA phylotypes on aquaria biofilms by DGGE, combined with nitrite and nitrate analysis, showed a correspondence between the appearance of Nitrospira-like bacterial ribosomal DNA and the initiation of nitrite oxidation. In total, the data suggest that Nitrobacter winogradskyi and close relatives were not the dominant nitrite-oxidizing bacteria in freshwater aquaria. Instead, nitrite oxidation in freshwater aquaria appeared to be mediated by bacteria closely related to Nitrospira moscoviensis and Nitrospira marina.

  14. 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.

  15. 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.

  16. Pemeriksaan Kandungan Nitrit Pada Produk Daging Sapi Olahan Yang Dijual Di Swalayan Kota Medan Tahun 2010

    OpenAIRE

    Waruwu, Faeri Indrani Priliyanti

    2011-01-01

    The processed beef products are the beef that have been processed to be various interesting meats such as corned, sausage beef jerky, shredded, beef burgers, bacon, meatballs and others. Processed meats always use preservative to prevent decomposition of meat. The preservatives used is nitrite which inhibit the growth of Clostridium botulinum. The general objective of this research is to determine the content of nitrite in processed beef products for sale in supermarkets Medan City in 201...

  17. 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.

  18. Nitrite-driven anaerobic methane oxidation by oxygenic bacteria.

    Science.gov (United States)

    Ettwig, Katharina F; Butler, Margaret K; Le Paslier, Denis; Pelletier, Eric; Mangenot, Sophie; Kuypers, Marcel M M; Schreiber, Frank; Dutilh, Bas E; Zedelius, Johannes; de Beer, Dirk; Gloerich, Jolein; Wessels, Hans J C T; van Alen, Theo; Luesken, Francisca; Wu, Ming L; van de Pas-Schoonen, Katinka T; Op den Camp, Huub J M; Janssen-Megens, Eva M; Francoijs, Kees-Jan; Stunnenberg, Henk; Weissenbach, Jean; Jetten, Mike S M; Strous, Marc

    2010-03-25

    Only three biological pathways are known to produce oxygen: photosynthesis, chlorate respiration and the detoxification of reactive oxygen species. Here we present evidence for a fourth pathway, possibly of considerable geochemical and evolutionary importance. The pathway was discovered after metagenomic sequencing of an enrichment culture that couples anaerobic oxidation of methane with the reduction of nitrite to dinitrogen. The complete genome of the dominant bacterium, named 'Candidatus Methylomirabilis oxyfera', was assembled. This apparently anaerobic, denitrifying bacterium encoded, transcribed and expressed the well-established aerobic pathway for methane oxidation, whereas it lacked known genes for dinitrogen production. Subsequent isotopic labelling indicated that 'M. oxyfera' bypassed the denitrification intermediate nitrous oxide by the conversion of two nitric oxide molecules to dinitrogen and oxygen, which was used to oxidize methane. These results extend our understanding of hydrocarbon degradation under anoxic conditions and explain the biochemical mechanism of a poorly understood freshwater methane sink. Because nitrogen oxides were already present on early Earth, our finding opens up the possibility that oxygen was available to microbial metabolism before the evolution of oxygenic photosynthesis.

  19. Reduction of Nitrite and Nitrate to Ammonium on Pyrite

    Science.gov (United States)

    Singireddy, Soujanya; Gordon, Alexander D.; Smirnov, Alexander; Vance, Michael A.; Schoonen, Martin A. A.; Szilagyi, Robert K.; Strongin, Daniel R.

    2012-08-01

    An important constraint on the formation of the building blocks of life in the Hadean is the availability of small, activated compounds such as ammonia (NH3) relative to its inert dinitrogen source. Iron-sulfur particles and/or mineral surfaces have been implicated to provide the catalytic active sites for the reduction of dinitrogen. Here we provide a combined kinetic, spectroscopic, and computational modeling study for an alternative source of ammonia from water soluble nitrogen oxide ions. The adsorption of aqueous nitrite (NO{2/-}) and nitrate (NO{3/-}) on pyrite (FeS2) and subsequent reduction chemistry to ammonia was investigated at 22°C, 70°C, and 120°C. Batch geochemical and in situ Attenuated Total Reflection - Fourier Transform Infrared (ATR-FTIR) spectroscopy experiments were used to determine the reduction kinetics to NH3 and to elucidate the identity of the surface complexes, respectively, during the reaction chemistry of NO{2/-} and NO{3/-}. Density functional theory (DFT) calculations aided the interpretation of the vibrational data for a representative set of surface species. Under the experimental conditions used in this study, we detected the adsorption of nitric oxide (NO) intermediate on the pyrite surface. NH3 production from NO{2/-} occurred at 70 and 120°C and from NO{3/-} occurred only at 120°C.

  20. [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.

  1. Quantitative risk assessment on the dietary exposure of Finnish children and adults to nitrite.

    Science.gov (United States)

    Suomi, Johanna; Ranta, Jukka; Tuominen, Pirkko; Putkonen, Tiina; Bäckman, Christina; Ovaskainen, Marja-Leena; Virtanen, Suvi M; Savela, Kirsti

    2016-01-01

    Nitrite intake from the consumption of cured meat and tap water was estimated for Finnish children of 1, 3 and 6 years as well as Finnish adults of 25-74 years. Nitrite content in the foods was measured by capillary electrophoresis, and was then used together with individual food consumption data from the FINDIET 2007 and DIPP studies in a stochastic exposure assessment by a Monte Carlo Risk Assessment (MCRA) program. Nitrite intake from additive sources and tap water was assessed, and more than every 10th child between the ages 3 and 6 years was estimated to have a nitrite intake exceeding the acceptable daily intake (ADI) of nitrite. The high exposure levels were caused by frequent consumption of large portions of sausages, up to 350 g day(-1) or 750 g in 3 days, among the children. Median nitrite intake from cured meat was 0.016, 0.040, 0.033 and 0.005 mg kg(-1) body weight day(-1) for children of 1, 3 and 6 years and adults, respectively. Bayesian estimation was employed to determine safe consumption levels of sausages and cold cuts for children, and these results gave rise to new national food consumption advice.

  2. Nitrite regulates hypoxic vasodilation via myoglobin-dependent nitric oxide generation.

    Science.gov (United States)

    Totzeck, Matthias; Hendgen-Cotta, Ulrike B; Luedike, Peter; Berenbrink, Michael; Klare, Johann P; Steinhoff, Heinz-Juergen; Semmler, Dominik; Shiva, Sruti; Williams, Daryl; Kipar, Anja; Gladwin, Mark T; Schrader, Juergen; Kelm, Malte; Cossins, Andrew R; Rassaf, Tienush

    2012-07-17

    Hypoxic vasodilation is a physiological response to low oxygen tension that increases blood supply to match metabolic demands. Although this response has been characterized for >100 years, the underlying hypoxic sensing and effector signaling mechanisms remain uncertain. We have shown that deoxygenated myoglobin in the heart can reduce nitrite to nitric oxide (NO·) and thereby contribute to cardiomyocyte NO· signaling during ischemia. On the basis of recent observations that myoglobin is expressed in the vasculature of hypoxia-tolerant fish, we hypothesized that endogenous nitrite may contribute to physiological hypoxic vasodilation via reactions with vascular myoglobin to form NO·. We show in the present study that myoglobin is expressed in vascular smooth muscle and contributes significantly to nitrite-dependent hypoxic vasodilation in vivo and ex vivo. The generation of NO· from nitrite reduction by deoxygenated myoglobin activates canonical soluble guanylate cyclase/cGMP signaling pathways. In vivo and ex vivo vasodilation responses, the reduction of nitrite to NO·, and the subsequent signal transduction mechanisms were all significantly impaired in mice without myoglobin. Hypoxic vasodilation studies in myoglobin and endothelial and inducible NO synthase knockout models suggest that only myoglobin contributes to systemic hypoxic vasodilatory responses in mice. Endogenous nitrite is a physiological effector of hypoxic vasodilation. Its reduction to NO· via the heme globin myoglobin enhances blood flow and matches O(2) supply to increased metabolic demands under hypoxic conditions.

  3. 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.

  4. 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.

  5. Nitrite in processed meat products in Khartoum, Sudan and dietary intake.

    Science.gov (United States)

    Adam, Aziza Hussein Bakheit; Mustafa, Nazik Eltayeb Musa; Rietjens, Ivonne M C M

    2017-06-01

    Nitrite intake from locally processed meat in Khartoum, Sudan was estimated and compared to established safety levels. For this purpose, 90 locally processed meat samples were collected randomly from retail outlets and analysed for nitrite levels according to the British standard 1992 protocol and 350 purchasers at retail outlets were questioned about their consumption pattern. Nitrite concentrations in all samples were below the Sudanese maximum limit (ML) of 100 mg kg-1 for nitrite in meat products. Dietary exposure to nitrite for adults and children was estimated to be in the range of 0.026-0.128 and 0.107-0.511 mg kg-1 bw day-1, respectively. This implies that nitrite intake for a significant number of consumers, especially children, are likely to exceed the established acceptable daily intake (ADI) of 0-0.07 mg kg-1 bw/day of JECFA, in spite the fact that meat samples collected complied with the current ML.

  6. 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.

  7. Nifurtimox biotransformation to reactive metabolites or nitrite in liver subcellular fractions and model systems.

    Science.gov (United States)

    Montalto de Mecca, M; Diaz, E G; Castro, J A

    2002-11-15

    Liver microsomal (mic); nuclei (N) and mitochondria (mit) anaerobically nitroreduce Nifurtimox (Nfx) in the presence of NADPH generating system. Simultaneous formation of small amounts of nitrite was observed in microsomes and nuclei but not in mitochondria. The microsomal nitroreductase activity was enhanced by the presence of flavine-adenine-dinucleotide disodium salt (FAD), was not inhibited by CO and was significantly inhibited by diphenyleneiodonium (DPI). In the microsomal NADPH-dependent fraction nitrite formation was null in the presence of FAD, DPI and under air and was partially inhibited by pure CO. Pure human cytochrome P450 reductase in the presence of NADPH significantly nitroreduced Nfx and produced small amounts of nitrite. The nitroreductive process was significantly enhanced by FAD but the nitrite formation became null. FAD itself was able to chemically nitroreduce Nfx without production of nitrite. NADPH generating system enhanced the FAD nitroreductive effect and led to small production of nitrite. Formation of reactive metabolites and nitric oxide during Nfx metabolism might contribute to its toxicity.

  8. Spectrophotometric determination of nitrite in soil and water using cefixime and central composite design

    Science.gov (United States)

    Shariati-Rad, Masoud; Irandoust, Mohsen; Mohammadi, Shabnam

    2015-10-01

    The present paper seeks to develop a simple method for the spectrophotometric determination of nitrite in soil and water samples and also measure optimum reaction conditions along with other analytical parameters. The method is based on the diazotization-coupling reaction of nitrite with cefixime and 1-naphthylamine in an acidic solution (Griess reaction). The final product that is an azo dye has an orange color with maximum absorption at 360 nm which Beer's Law is obeyed over the concentration range 0.02-15.00 mg L-1 of nitrite. Optimal conditions of the variables affecting the reaction were obtained by central composite design (CCD). A detection limit of 4.3 × 10-3 mg L-1 was obtained for determination of nitrite by the proposed method. The proposed method was successfully applied to determine nitrite in soil and water samples. The molar absorptivity of the product of the reaction and RSD in determination of nitrite in real samples are 4.1 × 103 (L mol-1 cm-1) and lower than 10%, respectively.

  9. Interference of Nitrite with Pyrite under Acidic Conditions: Implications for Studies of Chemolithotrophic Denitrification.

    Science.gov (United States)

    Yan, Ruiwen; Kappler, Andreas; Peiffer, Stefan

    2015-10-06

    Chemolithotrophic denitrification coupled to pyrite oxidation is regarded a key process in the removal of nitrate in aquifers. A common product is nitrite, which is a strong oxidant under acidic conditions. Nitrite may thus interfere with Fe(II) during acidic extraction, a procedure typically used to quantify microbial pyrite oxidation, in overestimating Fe(III) production. We studied the reaction between pyrite (5-125 mM) and nitrite (40-2000 μM) at pH 0, 5.5, and 6.8 in the absence and presence of oxygen. Significant oxidation of pyrite was measured at pH 0 with a yield of 100 μM Fe(III) after 5 mM pyrite was incubated with 2000 μM nitrite for 24 h. Dissolved oxygen increased the rate at pH 0. No oxidation of pyrite was observed at pH 5.5 and 6.8. Our data imply a cyclic model for pyrite oxidation by Fe(III) on the basis of the oxidation of residual Fe(II) by NO and NO2. Interference by nitrite could be avoided if nitrite was removed from the pyrite suspensions through a washing procedure prior to acidic extraction. We conclude that such interferences should be considered in studies on microbially mediated pyrite oxidation with nitrate.

  10. Consistent antioxidant and antihypertensive effects of oral sodium nitrite in DOCA-salt hypertension

    Directory of Open Access Journals (Sweden)

    Jefferson H. Amaral

    2015-08-01

    Full Text Available Hypertension is a common disease that includes oxidative stress as a major feature, and oxidative stress impairs physiological nitric oxide (NO activity promoting cardiovascular pathophysiological mechanisms. While inorganic nitrite and nitrate are now recognized as relevant sources of NO after their bioactivation by enzymatic and non-enzymatic pathways, thus lowering blood pressure, mounting evidence suggests that sodium nitrite also exerts antioxidant effects. Here we show for the first time that sodium nitrite exerts consistent systemic and vascular antioxidant and antihypertensive effects in the deoxycorticosterone-salt (DOCA-salt hypertension model. This is particularly important because increased oxidative stress plays a major role in the DOCA-salt hypertension model, which is less dependent on activation of the renin-angiotensin system than other hypertension models. Indeed, antihypertensive effects of oral nitrite were associated with increased plasma nitrite and nitrate concentrations, and completely blunted hypertension-induced increases in plasma 8-isoprostane and lipid peroxide levels, in vascular reactive oxygen species, in vascular NADPH oxidase activity, and in vascular xanthine oxidoreductase activity. Together, these findings provide evidence that the oral administration of sodium nitrite consistently decreases the blood pressure in association with major antioxidant effects in experimental hypertension.

  11. Plasma nitrite response in older women to a physical function test

    Science.gov (United States)

    Dobrosielski, Devon A.; Presley, Tennille; Perlegas, Andreas; Marsh, Anthony P.; Kim-Shapiro, Daniel; Rejeski, W. Jack

    2013-01-01

    Background and aims Nitric oxide (NO) may play a critical role in facilitating the delivery of blood to active skeletal muscle, ultimately impacting functional health in older adults. Plasma nitrite is a useful marker of vascular NO bioavailability. The aim of the current investigation was to examine the effect of a widely used physical function test on plasma nitrite concentrations in older adults. Methods Venous blood was drawn before, immediately following, and 10 minutes following the completion of a 400-m walk test. Blood samples were added to heparin and frozen for subsequent analysis of nitrite levels using chemiluminescence. Results Twenty six (79±4 yrs) women participated in this study. Plasma nitrite levels decreased approximately 22% from baseline following a 400-m walk. Percent change in plasma nitrite was related to walking speed (r=−0.550, p=0.004). Conclusions These data suggest an alteration in plasma nitrite concentration following a functional test which may impact functional health. PMID:20009500

  12. 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...

  13. Calcium and bones

    Science.gov (United States)

    ... eat in their diet. Vitamin D is the hormone that helps the gut absorb more calcium. Many older adults have common risks that make bone health worse. Calcium intake in the diet (milk, cheese, yogurt) is low. Vitamin D levels are ...

  14. 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...

  15. Extracellular Calcium and Magnesium

    African Journals Online (AJOL)

    ABSTRACT. The cause of preeclampsia remains unknown and calcium and magnesium supplement are being suggested as means of prevention. The objective of this study was to assess magnesium and calcium in the plasma and cerebrospinal fluid of Nigerian women with preedamp sia and eclampsia. Setting was ...

  16. The Effects of Physicochemical Factors and Cell Density on Nitrite Transformation in a Lipid-Rich Chlorella.

    Science.gov (United States)

    Liang, Fang; Du, Kui; Wen, Xiaobin; Luo, Liming; Geng, Yahong; Li, Yeguang

    2015-12-28

    To understand the effects of physicochemical factors on nitrite transformation by microalgae, a lipid-rich Chlorella with high nitrite tolerance was cultured with 8 mmol/l sodium nitrite as sole nitrogen source under different conditions. The results showed that nitrite transformation was mainly dependent on the metabolic activities of algal cells rather than oxidation of nitrite by dissolved oxygen. Light intensity, temperature, pH, NaHCO3 concentrations, and initial cell densities had significant effects on the rate of nitrite transformation. Single-factor experiments revealed that the optimum conditions for nitrite transformation were light intensity: 300 μmol/m(2); temperature: 30°C; pH: 7-8; NaHCO3 concentration: 2.0 g/l; and initial cell density: 0.15 g/l; and the highest nitrite transformation rate of 1.36 mmol/l/d was achieved. There was a positive correlation between nitrite transformation rate and the growth of Chlorella. The relationship between nitrite transformation rate (mg/l/d) and biomass productivity (g/l/d) could be described by the regression equation y = 61.3x (R(2) = 0.9665), meaning that 61.3 mg N element was assimilated by 1.0 g dry biomass on average, which indicated that the nitrite transformation is a process of consuming nitrite as nitrogen source by Chlorella. The results demonstrated that the Chlorella suspension was able to assimilate nitrite efficiently, which implied the feasibility of using flue gas for mass production of Chlorella without preliminary removal of NOX.

  17. 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

  18. 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...... 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 N2O production was low (∼2% of the oxidized ammonium). Net N2O production rates transiently increased with a rise in pH after each feeding, suggesting...

  19. 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.

  20. Parallel pathways for nitrite reduction during anaerobic growth in Thermus thermophilus.

    Science.gov (United States)

    Alvarez, Laura; Bricio, Carlos; Hidalgo, Aurelio; Berenguer, José

    2014-04-01

    Respiratory reduction of nitrate and nitrite is encoded in Thermus thermophilus by the respective transferable gene clusters. Nitrate is reduced by a heterotetrameric nitrate reductase (Nar) encoded along transporters and regulatory signal transduction systems within the nitrate respiration conjugative element (NCE). The nitrite respiration cluster (nic) encodes homologues of nitrite reductase (Nir) and nitric oxide reductase (Nor). The expression and role of the nirSJM genes in nitrite respiration were analyzed. The three genes are expressed from two promoters, one (nirSp) producing a tricistronic mRNA under aerobic and anaerobic conditions and the other (nirJp) producing a bicistronic mRNA only under conditions of anoxia plus a nitrogen oxide. As for its nitrite reductase homologues, NirS is expressed in the periplasm, has a covalently bound heme c, and conserves the heme d1 binding pocket. NirJ is a cytoplasmic protein likely required for heme d1 synthesis and NirS maturation. NirM is a soluble periplasmic homologue of cytochrome c552. Mutants defective in nirS show normal anaerobic growth with nitrite and nitrate, supporting the existence of an alternative Nir in the cells. Gene knockout analysis of different candidate genes did not allow us to identify this alternative Nir protein but revealed the requirement for Nar in NirS-dependent and NirS-independent nitrite reduction. As the likely role for Nar in the process is in electron transport through its additional cytochrome c periplasmic subunit (NarC), we concluded all the Nir activity takes place in the periplasm by parallel pathways.

  1. Acute toxicity of nitrate and nitrite to sensitive freshwater insects, mollusks, and a crustacean.

    Science.gov (United States)

    Soucek, D J; Dickinson, A

    2012-02-01

    Both point- and nonpoint-sources of pollution have contributed to increased inorganic nitrogen concentrations in freshwater ecosystems. Although numerous studies have investigated the toxic effects of ammonia on freshwater species, relatively little work has been performed to characterize the acute toxicity of the other two common inorganic nitrogen species: nitrate and nitrite. In particular, to our knowledge, no published data exist on the toxicity of nitrate and nitrite to North American freshwater bivalves (Mollusca) or stoneflies (Insecta, Plecoptera). We conducted acute (96-h) nitrate and nitrite toxicity tests with two stonefly species (Allocapnia vivipara and Amphinemura delosa), an amphipod (Hyalella azteca), two freshwater unionid mussels (Lampsilis siliquoidea and Megalonaias nervosa), a fingernail clam (Sphaerium simile), and a pond snail (Lymnaea stagnalis). Overall, we did not observe a particularly wide degree of variation in sensitivity to nitrate, with median lethal concentrations ranging from 357 to 937 mg NO(3)-N/l; furthermore, no particular taxonomic group appeared to be more sensitive to nitrate than any other. In our nitrite tests, the two stoneflies tested were by far the most sensitive, and the three mollusks tested were the least sensitive. In contrast to what was observed in the nitrate tests, variation among species in sensitivity to nitrite spanned two orders of magnitude. Examination of the updated nitrite database, including previously published data, clearly showed that insects tended to be more sensitive than crustaceans, which were in turn more sensitive than mollusks. Although the toxic mechanism of nitrite is generally thought to be the conversion of oxygen-carrying pigments into forms that cannot carry oxygen, our observed trend in sensitivity of broad taxonomic groups, along with information on respiratory pigments in those groups, suggests that some other yet unknown mechanism may be even more important.

  2. 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 (Iorg) 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

  3. Inhibitory Effects of Nitrite on Acid Production in Dental Plaque in Children.

    Science.gov (United States)

    Yamamoto, Yuji; Washio, Jumpei; Shimizu, Koichi; Igarashi, Koei; Takahashi, Nobuhiro

    To assess the inhibitory effects of nitrite on plaque acidogenicity and its relationship with caries experience. Plaque (2 μl) was collected from 76 children (age 5.8 ± 2.6 years, dmft 2.9 ± 3.5, DMTF 0.6 ± 1.4) and mixed with nitrite solution (final concentration = 0.63 mM) or distilled water (control). The initial pH (pH-0) of each sample was measured using a portable pH meter. The samples were incubated for 10 min, then their pH (pH-1) was measured again. Next, glucose (final concentration = 0.67%) was added to the samples, which were then incubated for a further 10 min before their pH was assessed for a third time (pH-2). The pH-0, pH-1, and pH-2 values of the control samples were 7.25 ± 0.16, 6.07 ± 0.44, and 5.11 ± 0.48, respectively, and those of the nitrite-treated samples were 7.26 ± 0.16, 6.37 ± 0.45, and 5.34 ± 0.48, respectively. The pH-1 and pH-2 values of the nitrite-treated samples were higher than those of the control samples (p plaque acid production was associated with stronger inhibition of plaque acid production by nitrite (p plaque acid production. Nitrite inhibited acid production more markedly in plaque that exhibited greater acid production, suggesting that nitrite might be effective at preventing caries, as it contributes to pH homeostasis in plaque by countering excess acidification.

  4. 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

  5. A Nitrite Biosensor Based on Co-immobilization of Nitrite Reductase and Viologen-modified Chitosan on a Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    De Quan

    2010-06-01

    Full Text Available An electrochemical nitrite biosensor based on co-immobilization of copper- containing nitrite reductase (Cu-NiR, from Rhodopseudomonas sphaeroides forma sp. denitrificans and viologen-modified chitosan (CHIT-V on a glassy carbon electrode (GCE is presented. Electron transfer (ET between a conventional GCE and immobilized Cu-NiR was mediated by the co-immobilized CHIT-V. Redox-active viologen was covalently linked to a chitosan backbone, and the thus produced CHIT-V was co-immobilized with Cu-NiR on the GCE surface by drop-coating of hydrophilic polyurethane (HPU. The electrode responded to nitrite with a limit of detection (LOD of 40 nM (S/N = 3. The sensitivity, linear response range, and response time (t90% were 14.9 nA/mM, 0.04−11 mM (r2 = 0.999 and 15 s, respectively. The corresponding Lineweaver-Burk plot showed that the apparent Michaelis-Menten constant (KMapp was 65 mM. Storage stability of the biosensor (retaining 80% of initial activity was 65 days under ambient air and room temperature storage conditions. Reproducibility of the sensor showed a relative standard deviation (RSD of 2.8% (n = 5 for detection of 1 mM of nitrite. An interference study showed that anions commonlyfound in water samples such as chlorate, chloride, sulfate and sulfite did not interfere with the nitrite detection. However, nitrate interfered with a relative sensitivity of 64% and this interference effect was due to the intrinsic character of the NiR employed in this study.

  6. Calcium sensing in exocytosis

    DEFF Research Database (Denmark)

    Gustavsson, Natalia; Wu, Bingbing; Han, Weiping

    2012-01-01

    Neurotransmitters, neuropeptides and hormones are released through regulated exocytosis of synaptic vesicles and large dense core vesicles. This complex and highly regulated process is orchestrated by SNAREs and their associated proteins. The triggering signal for regulated exocytosis is usually...... 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...

  7. Nitrite produced by Mycobacterium tuberculosis in human macrophages in physiologic oxygen impacts bacterial ATP consumption and gene expression

    OpenAIRE

    Cunningham-Bussel, Amy; Zhang, Tuo; Nathan, Carl F.

    2013-01-01

    Most people infected with Mycobacterium tuberculosis (Mtb) suppress the pathogen’s replication without eradicating it. It is unknown how Mtb survives for decades in a hostile host environment. Respiration of nitrate to nitrite could help Mtb survive in hypoxic tissues but was not thought to be significant at physiologic oxygen tensions, nor was the resultant nitrite considered consequential to Mtb’s physiology. We found that Mtb infecting human macrophages in vitro produces copious nitrite at...

  8. Influence of nitrite accumulation on "Candidatus Accumulibacter" population structure and enhanced biological phosphorus removal from municipal wastewater.

    Science.gov (United States)

    Zeng, Wei; Li, Boxiao; Wang, Xiangdong; Bai, Xinlong; Peng, Yongzhen

    2016-02-01

    A modified University of Cape Town (MUCT) process was used to treat real municipal wastewater with low carbon to nitrogen ratio (C/N). To our knowledge, this is the first study where the influence of nitrite accumulation on "Candidatus Accumulibacter" clade-level population structure was investigated during nitritation establishment and destruction. Real time quantitative PCR assays were conducted using the polyphosphate kinase 1 gene (ppk1) as a genetic marker. Abundances of total "Candidatus Accumulibacter", the relative distributions and population structure of the five "Candidatus Accumulibacter" clades were characterized. Under complete nitrification, clade I using nitrate as electron acceptor was below 5% of total "Candidatus Accumulibacter". When the reactor was transformed into nitritation, clade I gradually disappeared. Clade IID using nitrite as electron acceptor for denitrifying phosphorus (P) removal was always the dominant "Candidatus Accumulibacter" throughout the operational period. This clade was above 90% on average in total "Candidatus Accumulibacter", even up to nearly 100%, which was associated with good performance of denitrifying P removal via nitrite pathway. The nitrite concentrations affected the abundance of clade IID. The P removal was mainly completed by anoxic P uptake of about 88%. The P removal efficiency clearly had a positive correlation with the nitrite accumulation ratio. Under nitritation, the P removal efficiency was 30% higher than that under complete nitrification, suggesting that nitrite was appropriate as electron acceptor for denitrifying P removal when treating carbon-limited wastewater. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  9. Bone repair in calcium-deficient rats: comparison of xylitol+calcium carbonate with calcium carbonate, calcium lactate and calcium citrate on the repletion of calcium.

    Science.gov (United States)

    Hämäläinen, M M

    1994-06-01

    The potential value of xylitol in calcium therapy was evaluated by comparing the effect of dietary xylitol (50 g/kg diet) + calcium carbonate with the effects of calcium carbonate, calcium lactate and calcium citrate on bone repair of young male rats after the rats consumed for 3 wk a calcium-deficient diet (0.2 g Ca/kg diet). After this calcium-depletion period, the rats were fed for 2 wk one of four diets, each containing 5 g Ca/kg diet as one of the four dietary calcium sources. The diet of the control animals was supplemented with CaCO3 (5 g Ca/kg diet) throughout the study. The Ca-deficient rats showed low bone mass, low serum calcium and high serum 1,25-dihydroxycholecalciferol, parathyroid hormone (1-34 fraction) and osteocalcin concentrations. They also excreted magnesium, phosphate and hydroxyproline in the urine in high concentrations, and had high bone alkaline phosphatase and tartrate-resistant acid phosphatase activities. Most of these changes were reversed by the administered of the calcium salts. The highest recoveries of femoral dry weight, calcium, magnesium and phosphate were observed in the groups receiving xylitol+CaCO3 and calcium lactate. Calcium lactate and calcium citrate caused low serum phosphate concentration compared with rats receiving CaCO3 and with the age-matched Ca-replete controls. Xylitol-treated rats excreted more calcium and magnesium in urine than did the other rats, probably due to increased absorption of these minerals from the gut. These results suggest that dietary xylitol improves the bioavailability of calcium salts.

  10. A case study of nitrification and nitrite isotope fractionation in a eutrophic temperate river system

    Science.gov (United States)

    Jacob, Juliane; Dähnke, Kirstin; Sanders, Tina

    2014-05-01

    Stable isotopes of nitrate are often used to assess processing of nitrate in the water column of oceans, estuaries, and rivers. In all these environments, nitrate regeneration via nitrification is an important source of new nitrate. The bulk isotope effect of nitrification is hard to predict: It is a two-step-process by distinct groups of microorganisms oxidizing ammonium to nitrate via nitrite. Both processes have divergent isotope effects, and it is even more difficult to unravel these effects in natural environments, because nitrite usually does not accumulate and isotope analysis is not possible. During our routine sampling scheme at the River Elbe an exceptional flood occurred in June 2013, and nitrite and ammonium accumulated, allowing us to investigate isotope fractionation of nitrification in a natural river system. We measured nutrient concentrations, dual nitrate isotopes, δ15N-NO2, and, where possible, δ15N-NH4. Nitrate leached from catchment area, and δ15N-NO3 and δ18O-NO3 decreased from typical spring bloom values (9.0 o and 3.5 o respectively) to winter nitrate background values (7.4 o and 2.1 o respectively). This indicates that riverine assimilation was minimal during the flood. Ammonium and nitrite concentrations increased to 12.5 μM and 5.7 μM, respectively, which likely was due to remineralization and nitrification in the water column. Ammonium δ15N-NH4 values increased up to 12 o and nitrite δ15N-NO2 values ranged from -4.8 o and -14.2 ‰Nitrite oxidation and decreasing concentrations were coupled with a fractionation factor 15ɛ of -8.6 o following normal, and not inverse, isotope fractionation. This deviates from findings in pure cultures of nitrite-oxidizing bacteria. We assume that the mechanisms responsible for inverse fractionation apply in natural environment as well, but that the resulting trend in δ15N-NO2 is masked by dilution with fresh nitrite stemming from ammonium oxidation. Our data are a first approximation of the

  11. Calcium – how and why?

    Indian Academy of Sciences (India)

    Unknown

    Calcium is among the most commonly used ions, in a multitude of biological functions, so much so that it is impossible to imagine life without calcium. In this article I have attempted to address the question as to how calcium has achieved this status with a brief mention of the history of calcium research in biology. It appears ...

  12. Calcium and Your Child

    Science.gov (United States)

    ... Milk Allergy Figuring Out Food Labels What's a Vegetarian? Osteoporosis Minerals Your Bones Mineral Chart Vitamin D ... Need to Drink Milk? Lactose Intolerance Becoming a Vegetarian Soy Foods and Health Calcium Bones, Muscles, and ...

  13. Stoichiometry of Calcium Medicines

    Science.gov (United States)

    Pinto, Gabriel

    2005-01-01

    The topic of calcium supplement and its effects on human lives is presented in the way of questions to the students. It enables the students to realize the relevance of chemistry outside the classroom surrounding.

  14. Magnesium, calcium and cancer

    National Research Council Canada - National Science Library

    Anghileri, Leopoldo J

    2009-01-01

    Magnesium ion (Mg(2+)) and calcium ion (Ca(2+)) control a diverse and important range of cellular processes, such as gene transcription, cell proliferation, neoplastic transformation, immune response and therapeutic treatment...

  15. 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. PMID:25423449

  16. 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.

  17. 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.

  18. 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 (PDMDL 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.

  19. 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.

  20. Nitrite is a positive modulator of the Frank-Starling response in the vertebrate heart.

    Science.gov (United States)

    Angelone, Tommaso; Gattuso, Alfonsina; Imbrogno, Sandra; Mazza, Rosa; Tota, Bruno

    2012-06-01

    Evidence from both mammalian and nonmammalian vertebrates indicates that intracardiac nitric oxide (NO) facilitates myocardial relaxation, ventricular diastolic distensibility, and, consequently, the Frank-Starling response, i.e., the preload-induced increase of cardiac output. Since nitrite ion (NO(2)(-)), the major storage pool of bioactive NO, recently emerged as a cardioprotective endogenous modulator, we explored its influence on the Frank-Starling response in eel, frog, and rat hearts, used as paradigms of fish, amphibians, and mammals, respectively. We demonstrated that, like NO, exogenous nitrite improves the Frank-Starling response in all species, as indicated by an increase of stroke volume and stroke work (eel and frog) and of left ventricular (LV) pressure and LVdP/dt max (rat), used as indexes of inotropism. Unlike in frog and rat, in eel, the positive influence of nitrite appeared to be dependent on NO synthase inhibition. In all species, the effect was sensitive to NO scavengers, independent on nitroxyl anion, and mediated by a cGMP/PKG-dependent pathway. Moreover, the nitrite treatment increased S-nitrosylation of lower-molecular-weight proteins in cytosolic and membrane fractions. These results suggest that nitrite acts as a physiological source of NO, modulating through different species-specific mechanisms, the stretch-induced intrinsic regulation of the vertebrate heart.

  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. Enhancement of Nitrite Oxidation by Heat-Treated Cobalt Phthalocyanine Supported on High Area Carbon

    Energy Technology Data Exchange (ETDEWEB)

    Baik, Bong Yong; Kim, Sung Hyun [Konkuk University, Seoul (Korea, Republic of); Kwag, Gwang Hoon [Kumho Chemical Laboratories, Daejeon (Korea, Republic of)

    2006-02-15

    We have shown that the higher catalytic activity of heat-treated CoPc toward the nitrite oxidation comes from both Co-N{sub x} structure and highly dispersed cobalt metal ion characteristics. This result can be compared with FePc case in which the Fe-N{sub x} structure existed even after heat-treatment at 1000 .deg. C. However, almost entire CoPc molecules were converted to metallic Co. Therefore, the best electrocatalyst could be prepared by any means to give Co-N{sub x} characteristics and high degree of dispersion of Co metal atoms. Our ongoing effort is to develop efficient electrocatalysts and sensors for nitrite detection. Nitrite is one of the major components of wastewater from nuclear power production and involved in the corrosion and bacterial process known as the nitrogen cycle. It also plays important physiological roles in the form of NO, for example, as an intra- and intercellular messenger, a neurotransmitter, and an immune system mediator. The detection of nitrite, therefore, is important from an environmental and biological point of view. We have been utilizing transition-metal (particularly Fe and Co) phthalocyanines and porphyrins for this purpose as they often display catalytic activities toward many important electrochemical reactions such as oxygen reduction and CO oxidation. We found that iron phthalocyanine (FePc) is a very effective catalyst for nitrite reduction, undergoing structural changes on the surface as a function of the redox state.

  3. Redox-state-dependent complex formation between pseudoazurin and nitrite reductase.

    Science.gov (United States)

    Impagliazzo, Antonietta; Blok, Anneloes J; Cliff, Matthew J; Ladbury, John E; Ubbink, Marcellus

    2007-01-10

    Bacterial copper-containing nitrite reductase catalyzes the reduction of nitrite to nitric oxide as part of the denitrification process. Pseudoazurin interacts with nitrite reductase in a transient fashion to supply the necessary electrons. The redox-state dependence of complex formation between pseudoazurin and nitrite reductase was studied by nuclear magnetic resonance spectroscopy and isothermal titration calorimetry. Binding of pseudoazurin in the reduced state is characterized by the presence of two binding modes, a slow and a fast exchange mode, with a K(d)(app) of 100 microM. In the oxidized state of pseudoazurin, binding occurs in a single fast exchange mode with a similar affinity. Metal-substituted proteins have been used to show that the mode of binding of pseudoazurin is independent of the metal charge of nitrite reductase. Contrary to what was found for other cupredoxins, protonation of the exposed His ligand to the copper of pseudoazurin, His81, does not appear to be involved directly in the dual binding mode of the reduced form. A model assuming the presence of a minor form of pseudoazurin is proposed to explain the behavior of the complex in the reduced state.

  4. 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 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 gr......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...... number of experiments were conducted in Denmark in collaboration with the Danish meat manufacturing industry in 1981-1983. Wiltshire bacon and certain canned products largely for export were not investigated in this study, however. The adverse effects of nitrite can mainly be ascribed to the risk...... sausages. Arguments for maintaining this high level are lacking in the available literature, and on the basis of what can be deduced with respect to the manufacturing processes for these products, it is hard to conceive of substantial arguments for the high level of 180 mg/kg. For other heat...

  5. The Medicinal Chemistry of Nitrite as a Source of Nitric Oxide Signaling.

    Science.gov (United States)

    Blood, Arlin B

    2017-01-01

    Conventional understanding of nitric oxide (NO) signaling in biology is commonly based on the premise that it simply diffuses randomly from its site of production by NO synthases to its site of action or inactivation. This notion has been challenged on a systemic cardiovascular scale with the realization that NO has endocrine effects despite being unable to exist in blood for more than a few milliseconds. Investigation of this phenomenon has led to the understanding that many of the chemical pathways that consume NO may not render it inactive as once thought. Instead, many of NO's metabolic products are still capable of carrying out NO signaling, or participate in NO-independent signaling in their own right. Nitrite and nitrate are two such products of NO metabolism that were once thought to be inert at physiological concentrations but are now known to contribute to NO bioactivity. The activity of nitrate is dependent upon its reduction to nitrite by bacterial nitrate reductase activity in the mouth. Nitrite can be reduced to NO by several metal-containing proteins under hypoxic conditions, or by nonenzymatic reactions under acidic conditions. Reduction and oxidation products of nitrite metabolism may also result in the production of NO adducts with a wide array of biological functions. The following review provides a general overview of the basic pathways underlying the physiological activity of nitrate and nitrite, as well as insight into the therapeutic potential of these pathways. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  6. 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.

  7. [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

  8. Survey the effects of dietary sodium nitrite on the histological changes of the aortic artery in the adult male rats

    Directory of Open Access Journals (Sweden)

    Saeaid Khatamsaz

    2016-05-01

    Full Text Available Background: Because of high consumption of nitrite in processed (fast foods and high level of nitrite in water, soil and ecosystem, nitrite can endanger humans health. In this study the effects of sodium nitrite on aorta was examined in adult male rats. Materials and Methods : In the present study, 30 Wistar adult male rats were randomly divided into three groups of 10, including; control group. First experimental group that received low dose of sodium nitrite (175 mg/kg.bw, second experimental group that received high dose of sodium nitrite (350 mg/kg.bw. They were examined for 60 days. The rats got sodium nitrite through drinking water. At the end of the experiment the rats were taken to the anesthesia jar and based on ether principles, they anesthetized with ether and their blood samples were collected from their hearts. Then their aorta were extracted from their bodies and the tissue sections were prepared for testing tissue changes. Features such as histological features of aorta (morphometric and morphologic features were analyzed. The samples were stained with masson trichrome and Hematoxylin- Eosin methods. The internal media layer was measured with Image tool software. Then the amount of nitrite oxide in their blood were tested. At the end results were analyzed by 17 version of SPSS software and ANOVA test was run. Results: The results of this study showed that thickness of medial layer in two experimental group that received low and high dose of sodium nitrite compared with the control group decreased (p 0.05, and the group that received of high dose of sodium nitrite showed irregular and non- uniform state in aortic media layer. Conclusion: The finding of this study indicated that consumption of sodium nitrite in long term can induce damage in artries tissue.

  9. Comparative transcriptome analysis reveals molecular strategies of oriental river prawn Macrobrachium nipponense in response to acute and chronic nitrite stress.

    Science.gov (United States)

    Xu, Zhixin; Li, Tongyu; Li, Erchao; Chen, Ke; Ding, Zhili; Qin, Jian G; Chen, Liqiao; Ye, Jinyun

    2016-01-01

    Macrobrachium nipponense is an economically and nutritionally important species threatened by ambient superfluous nitrite. De novo RNA-Seq was used to explore the molecular mechanism in M. nipponense exposed to the acute nitrite stress (26.05 mg/L nitrite-N) for 24 h and the chronic nitrite stress (1.38 mg/L nitrite-N) for 28 d A total of 175.13 million reads were obtained and assembled into 58,871 unigenes with an average length of 1028.7 bp and N50 of 1294 bp. Under the acute and chronic nitrite stress trials, 2824 and 2610 unigenes were significantly expressed. In GO analysis and KEGG pathway analysis, 30 pathways were significantly different between the two treatments while four pathways were in common and the markedly altered pathways were divided into four sections as immunity, metabolism, cell and others. The immunity section revealing the different depth of immunity provoked by nitrite stress contained the most pathways including the important pathways as phagosome, folate biosynthesis, glycerolipid metabolism, glycine, serine and threonine metabolism, amino sugar and nucleotide sugar metabolism under the acute nitrite stress, and lysosome, alanine, aspartate and glutamate metabolism, arginine and proline metabolism under the chronic nitrite stress. This is the first report of responses of M. nipponense under acute and chronic nitrite stress through de novo transcriptome sequencing on the transcriptome level. The results of transcriptome analysis improve our understanding on the underlying molecular mechanisms coping with nitrite stress in crustacean species. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Nitrite sensing based on the carbon dots-enhanced chemiluminescence from peroxynitrous acid and carbonate.

    Science.gov (United States)

    Lin, Zhen; Dou, Xiangnan; Li, Haifang; Ma, Yuan; Lin, Jin-Ming

    2015-01-01

    In this work, chemiluminescence (CL) from peroxynitrous acid (ONOOH)-carbonate system greatly amplified by carbon dots was observed. The CL mechanism of the ONOOH-carbonate-carbon dots system has been investigated and the results reveal that the carbon dots could serve as the energy acceptor, which gives us new insight into the optical properties of the new emerging carbon nanomaterial. There is a good linear relationship between the CL signal and the concentration of the nitrite using for ONOOH formation, which provides us a nitrite sensing method with sensitivity as high as 5.0×10(-9) M (S/N=3). The method has been successfully applied to the determination of nitrite in tap water with the recovery of 98%. The standard deviations are within 2.5%. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Invasion of nitrite oxidizer dominated communities: interactions between propagule pressure and community composition

    DEFF Research Database (Denmark)

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

    Managing invasion of microbial communities by new members can be a powerful tool in microbial resource management. Abundant studies have examined how resource availability and resident community diversity affect invasion success. Yet, a more rigorous approach towards studying invasion would...... reported. The objective of this study was to determine the effect of propagule pressure on invasion success in microbial communities, shaped by varying degrees of stochasticity and determinism. The experimental system consisted of nitrite oxidizing bacterial enrichments, developed in replicate flow......-through biofilm reactors using drinking water as inoculum and continuous feeding with nitrite a sole energy source. Different nitrite loading rates were applied, as these were previously shown to influence nitrifying guild composition and stochasticity [1]. After 6 weeks, the reactors were invaded for 24 hours...

  12. Partial replacement of nitrite by annatto as a colour additive in sausage.

    Science.gov (United States)

    Zarringhalami, S; Sahari, M A; Hamidi-Esfehani, Z

    2009-01-01

    For decreasing the use of nitrite in sausage in industrial conditions, annatto (Bixa orellana L.) powder (1% norbixin) was used in two different formulations of sausage (with 55% and 70% of meat) as a replacement for 20%, 40%, 60%, 80% and 100% nitrite. Then the qualitative characteristics of the samples such as colour (L(∗), a(∗) and b(∗)), microbial contamination and sensory tests (flavour and odour) were compared with the control (without annatto and with 100% nitrite) after 2, 10, 20 and 30 days from production and under the refrigerated condition. The Statistical comparison showed that in both formulations of sausage, the sample containing 60% annatto was the best sample for its colour (for higher a(∗) and lower b(∗)); yet, this sample also did not show any significant differences from the control for microbial contamination and sensory properties.

  13. Adaptability as the key to success for the ubiquitous marine nitrite oxidizer Nitrococcus.

    Science.gov (United States)

    Füssel, Jessika; Lücker, Sebastian; Yilmaz, Pelin; Nowka, Boris; van Kessel, Maartje A H J; Bourceau, Patric; Hach, Philipp F; Littmann, Sten; Berg, Jasmine; Spieck, Eva; Daims, Holger; Kuypers, Marcel M M; Lam, Phyllis

    2017-11-01

    Nitrite-oxidizing bacteria (NOB) have conventionally been regarded as a highly specialized functional group responsible for the production of nitrate in the environment. However, recent culture-based studies suggest that they have the capacity to lead alternative lifestyles, but direct environmental evidence for the contribution of marine nitrite oxidizers to other processes has been lacking to date. We report on the alternative biogeochemical functions, worldwide distribution, and sometimes high abundance of the marine NOB Nitrococcus. These largely overlooked bacteria are capable of not only oxidizing nitrite but also reducing nitrate and producing nitrous oxide, an ozone-depleting agent and greenhouse gas. Furthermore, Nitrococcus can aerobically oxidize sulfide, thereby also engaging in the sulfur cycle. In the currently fast-changing global oceans, these findings highlight the potential functional switches these ubiquitous bacteria can perform in various biogeochemical cycles, each with distinct or even contrasting consequences.

  14. 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

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

    Directory of Open Access Journals (Sweden)

    Bárbara S. Rocha

    2016-08-01

    Full Text Available 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 (p<0.05 and nitrated pepsin was detected both in the gastric juice and the mucosa (p<0.05. Exogenous urate, a scavenger of nitrogen dioxide radical, blunted •NO detection and inhibited pepsin nitration, suggesting an underlining free radical-dependent mechanism for nitration. Functionally, pepsin nitration prevented the development of gastric ulcers, as the lesions were only apparent when pepsin nitration was inhibited by urate. In sum, this work unravels a novel dietary-dependent nitrating pathway in which pepsin is nitrated and inactivated in the stomach, preventing the progression of gastric ulcers.

  16. Investigation of the photocatalytic effect of zinc oxide nanoparticles in the presence of nitrite

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Min; Abbood, Hayder A. [School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074 (China); Institute of Inorganic Chemistry and Chemical Biology, Hubei key Laboratory of Bioinorganic Chemistry and Medicine, 1037 Luoyu Road, Wuhan 430074 (China); Zhu, Zhening [National Center for Nanoscience and Technology, No.11 ZhongGuanCun BeiYiTiao Road, Beijing 100190 (China); Li, Hailing [School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074 (China); Institute of Inorganic Chemistry and Chemical Biology, Hubei key Laboratory of Bioinorganic Chemistry and Medicine, 1037 Luoyu Road, Wuhan 430074 (China); Gao, Zhonghong, E-mail: zhgao144@mail.hust.edu.cn [School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074 (China); Institute of Inorganic Chemistry and Chemical Biology, Hubei key Laboratory of Bioinorganic Chemistry and Medicine, 1037 Luoyu Road, Wuhan 430074 (China)

    2013-01-15

    Highlights: ► Nitrite enhanced the photo-damage by ZnO nanoparticles to BSA and HaCaT cells. ► Protein nitration was induced by nitrite in photo-damaged BSA and HaCaT cells. ► The effects of photo-damage on BSA were affected by various factors. ► 50-nm ZnO induced more apoptosis than 90-nm ZnO in HaCaT cells. -- Abstract: Zinc oxide nanoparticles are widely used in sunscreen products because of their chemical stability and capability of blocking harmful ultraviolet rays. However, zinc oxide nanoparticles can also generate reactive species under ultraviolet irradiation. Because nitrite can form reactive nitrogen species under oxidative stress and because it exists in perspiration and cosmetics, we studied the effects of nitrites on the photocatalytic damage of zinc oxide nanoparticles (50 nm and 90 nm) to bovine serum albumin and human keratinocyte cells under ultraviolet irradiation (365 nm and 254 nm). The results indicate that nitrite plays an enhancing role in photocatalytic damage by breaking amino acid residues and promoting protein oxidation and nitration. The concentrations of zinc oxide and nitrite, the irradiation light and duration, and the pH of the medium are important factors influencing this photocatalytic damage. Size effects of ZnO nanoparticles on bovine serum albumin and keratinocyte cells are different. It is speculated that the extent of photo-damage is partially dependent on the aggregation of zinc oxide. These findings may be valuable for understanding potential risks of applying zinc oxide nanoparticle-containing sunscreens to human skin under sunlight exposure.

  17. Nitrite Regulates Hypoxic Vasodilation via Myoglobin–Dependent Nitric Oxide Generation

    Science.gov (United States)

    Totzeck, Matthias; Hendgen-Cotta, Ulrike B.; Luedike, Peter; Berenbrink, Michael; Klare, Johann P.; Steinhoff, Heinz-Juergen; Semmler, Dominik; Shiva, Sruti; Williams, Daryl; Kipar, Anja; Gladwin, Mark T.; Schrader, Juergen; Kelm, Malte; Cossins, Andrew R.; Rassaf, Tienush

    2012-01-01

    Background Hypoxic vasodilation is a physiological response to low oxygen (O2) tension that increases blood supply to match metabolic demands. While this response has been characterized for more than 100 years, the underlying hypoxic sensing and effector signaling mechanisms remain uncertain. We have shown that deoxygenated myoglobin (deoxyMb) in the heart can reduce nitrite to nitric oxide (NO˙) and thereby contribute to cardiomyocyte NO˙ signaling during ischemia. Based on recent observations that Mb is expressed in the vasculature of hypoxia-tolerant fish, we hypothesized that endogenous nitrite may contribute to physiological hypoxic vasodilation via reactions with vascular Mb to form NO˙. Methods and Results We here show that Mb is expressed in vascular smooth muscle and contributes significantly to nitrite-dependent hypoxic vasodilation in vivo and ex vivo. The generation of NO˙ from nitrite reduction by deoxyMb activates canonical soluble guanylate cyclase (sGC)/cyclic guanosine monophosphate (cGMP) signaling pathways. In vivo and ex vivo vasodilation responses, the reduction of nitrite to NO˙ and the subsequent signal transduction mechanisms were all significantly impaired in mice without myoglobin (Mb−/−). Hypoxic vasodilation studies in Mb, endothelial and inducible NO synthase knockout models (eNOS−/−, iNOS−/−) suggest that only Mb contributes to systemic hypoxic vasodilatory responses in mice. Conclusions Endogenous nitrite is a physiological effector of hypoxic vasodilation. Its reduction to NO˙ via the heme globin Mb enhances blood flow and matches O2 supply to increased metabolic demands under hypoxic conditions. PMID:22685116

  18. The stability of accumulating nitrite from Swine wastewater in a sequencing batch reactor.

    Science.gov (United States)

    Wang, Liang; Zhu, Jun; Miller, Curtis

    2011-02-01

    Shortcut nitrification is the first step of shortcut nitrogen removal from swine wastewater. Stably obtaining an effluent with a significant amount of nitrite is the premise for the subsequent shortcut denitrification. In this paper, the stability of nitrite accumulation was investigated using a 1.5-day hydraulic retention time in a 10-L (working volume) activated sludge sequencing batch reactor (SBR) with an 8-h cycle consisted of 4 h 38 min aerobic feeding, 1 h 22 min aerobic reaction, 30 min settling, 24 min withdrawal, and 1 h 6 min idle. The nitrite production stability was tested using four different ammonium loading rates, 0.075, 0.062, 0.053, and 0.039 g NH(4)-N/g (mixed liquid suspended solid, MLSS) day in a 2-month running period. The total inorganic nitrogen composition in the effluent was not affected when the ammonium load was between 0.053 and 0.075 g NH(4)-N/g MLSS · day (64% NO(2)-N, 16% NO(3)-N, and 20% NH(4)-N). Under 0.039 g NH(4)-N/g MLSS · day, more NO(2)-N was transformed to NO(3)-N with an effluent of 60% NO(2)-N, 20% NO(3)-N, and 20% NH(4)-N. The reducing load test was able to show the relationship between a declining free nitrous acid (FNA) concentration and the decreasing nitrite production, indicating that the inhibition of FNA on nitrite oxidizing bacteria depends on its levels and an ammonium loading rate around 0.035 g NH(4)-N/g MLSS · day is the lower threshold for producing a nitrite dominance effluent in the activated sludge SBR under the current settings.

  19. Analysis of nitrite/nitrate in biological fluids: denitrification of 2-nitropropane in F344 rats.

    Science.gov (United States)

    Sohn, O S; Fiala, E S

    2000-03-15

    2-Nitropropane (2-NP), a rat hepatocarcinogen, is denitrified to nitrite and acetone by rat liver microsomes; the denitrification rate is increased using microsomes from phenobarbital (PB)-pretreated rats. To obtain evidence that denitrification of 2-NP also occurs in vivo, we attempted to determine nitrite and nitrate levels in blood sera and urines of 2-NP-treated (1.5 mmol/kg, ip, once) rats with and without PB pretreatment (80 mg/kg, ip, once daily, 3 days), using enzymatic reduction followed by the standard Griess reaction. However, due to various interfering factors, including pigment from methemoglobinemia, we found the assay had to be modified as follows: (a) reduction of nitrate to nitrite was accomplished using NADPH and nitrate reductase, (b) excess NADPH, proteins, and interfering pigments were precipitated using zinc acetate and Na(2)CO(3), and (c) the Griess reagents were prepared in 3 N HCl rather than 5% H(3)PO(4). With these modifications it became possible to show that 2-NP is indeed metabolized to nitrite in vivo and that the metabolism is increased by PB pretreatment. Two hours after 2-NP administration, rat blood serum nitrate plus nitrite levels were approximately 1600 microM (PB-pretreated) and 940 microM (vehicle-pretreated controls). The PB-pretreated and control rats, respectively, excreted 250 and 120 micromol nitrate/nitrite in the 24-h urine post 2-NP treatment. The modifications described make the method more specific, reproducible, and more widely applicable. Copyright 2000 Academic Press.

  20. Investigation of Ammonium and Nitrite Removal by Zeolite Material Synthesized on Red Mud Base

    Directory of Open Access Journals (Sweden)

    Pham Thi Mai Huong

    2017-07-01

    Full Text Available The zeolite with the unit formula of Na8(Al6Si6O24S.4H2O was synthesized directly on red mud base with addition of single silicon (signed as RH-ZeO-Si and both silicon and aluminum portions (signed as RM-ZeO-SiAl to original Tan Rai (Vietnam red mud. The structure of the zeolite was studied by X-Ray difration and FT-IR absorption spectra. The synthesized materials were studied on their adsorption ability of ammonium and nitrite ions. The results showed that, the adsorption of ammonium cation was mostly allowing ion-exchange mechanism and the zeolite crystaline forms played predominantly role besids minor one of single metal oxides. For nitrite anions, it is otherwise, the adsorption mechanism was mostly leant to electrostatic attraction between nitrite anions and electropositive effect of the hematite surface in light acidic condition. The adsorption isotherms of all ammonium and nitrite ions on both synthesized materials were nearly conformable with Freundlich model than Langmuir model. Those showed that, both materials have unhomogeneous adsorption surface. The maximum adsorption capacity of ammonium and nitrite on RM-ZeO-Si was 5.71 mg/g and 2.73 mg/g respectively, and on RM-ZeO-SiAl was 5.61 mg/g and 3.12 mg/g respectively. The initial test of competitive ions influencing on adsorption ability showed that, for all cases the competition of cations to ammonium ion was more significance than those of anions to nitrite ion in the same conditions.

  1. 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.

  2. Modeling nitrogen removal with partial nitritation and anammox in one floc-based sequencing batch reactor.

    Science.gov (United States)

    Ni, Bing-Jie; Joss, Adriano; Yuan, Zhiguo

    2014-12-15

    Full-scale application of partial nitritation and anammox in a single floc-based sequencing batch reactor (SBR) has been achieved for high-rate nitrogen (N) removal, but mechanisms resulting in reliable operation are not well understood. In this work, a mathematical model was calibrated and validated to evaluate operating conditions that lead to out-competition of nitrite oxidizers (NOB) from the SBRs and allow to maintain high anammox activity during long-term operation. The validity of the model was tested using experimental data from two independent previously reported floc-based full-scale SBRs for N-removal via partial nitritation and anammox, with different aeration strategies at aeration phase (continuous vs. intermittent aeration). The model described the SBR cycle profiles and long-term dynamic data from the two SBR plants sufficiently and provided insights into the dynamics of microbial population fractions and N-removal performance. Ammonium oxidation and anammox reaction could occur simultaneously at DO range of 0.15-0.3 mg O2 L(-1) at aeration phase under continuous aeration condition, allowing simplified process control compared to intermittent aeration. The oxygen supply beyond prompt depletion by ammonium oxidizers (AOB) would lead to the growth of NOB competing with anammox for nitrite. NOB could also be washed out of the system and high anammox fractions could be maintained by controlling sludge age higher than 40 days and DO at around 0.2 mg O2 L(-1). Furthermore, the results suggest that N-removal in SBR occurs via both alternating nitritation/anammox and simultaneous nitritation/anammox, supporting an alternative strategy to improve N-removal in this promising treatment process, i.e., different anaerobic phases can be implemented in the SBR-cycle configuration. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. [Microbial geochemical calcium cycle].

    Science.gov (United States)

    Zavarzin, G A

    2002-01-01

    The participation of microorganisms in the geochemical calcium cycle is the most important factor maintaining neutral conditions on the Earth. This cycle has profound influence on the fate of inorganic carbon, and, thereby, on the removal of CO2 from the atmosphere. The major part of calcium deposits was formed in the Precambrian, when prokaryotic biosphere predominated. After that, calcium recycling based on biogenic deposition by skeletal organisms became the main process. Among prokaryotes, only a few representatives, e.g., cyanobacteria, exhibit a special calcium function. The geochemical calcium cycle is made possible by the universal features of bacteria involved in biologically mediated reactions and is determined by the activities of microbial communities. In the prokaryotic system, the calcium cycle begins with the leaching of igneous rock predominantly through the action of the community of organotrophic organisms. The release of carbon dioxide to the soil air by organotrophic aerobes leads to leaching with carbonic acid and soda salinization. Under anoxic conditions, of major importance is the organic acid production by primary anaerobes (fermentative microorganisms). Calcium carbonate is precipitated by secondary anaerobes (sulfate reducers) and to a smaller degree by methanogens. The role of the cyanobacterial community in carbonate deposition is exposed by stromatolites, which are the most common organo-sedimentary Precambrian structures. Deposition of carbonates in cyanobacterial mats as a consequence of photoassimilation of CO2 does not appear to be a significant process. It is argued that carbonates were deposited at the boundary between the "soda continent", which emerged as a result of subaerial leaching with carbonic acid, and the ocean containing Ca2+. Such ecotones provided favorable conditions for the development of the benthic cyanobacterial community, which was a precursor of stromatolites.

  4. Effects of Nitrite and Erythorbate on Clostridium perfringens Growth during Extended Cooling of Cured Ham.

    Science.gov (United States)

    Osterbauer, Katie J; King, Amanda M; Seman, Dennis L; Milkowksi, Andrew L; Glass, Kathleen A; Sindelar, Jeffrey J

    2017-10-01

    To control the growth of Clostridium perfringens in cured meat products, the meat and poultry industries commonly follow stabilization parameters outlined in Appendix B, "Compliance Guidelines for Cooling Heat-Treated Meat and Poultry Products (Stabilization)" ( U.S. Department of Agriculture, Food Safety and Inspection Service [USDA-FSIS], 1999 ) to achieve cooling (54.4 to 4.4°C) within 15 h after cooking. In this study, extended cooling times and their impact on C. perfringens growth were examined. Phase 1 experiments consisted of cured ham with 200 mg/kg ingoing sodium nitrite and 547 mg/kg sodium erythorbate following five bilinear cooling profiles: a control (following Appendix B guidelines: stage A cooling [54.4 to 26.7°C] for 5 h, stage B cooling [26.7 to 4.4°C] for 10 h), extended stage A cooling for 7.5 or 10 h, and extended stage B cooling for 12.5 or 15 h. A positive growth control with 0 mg/kg nitrite added (uncured) was also included. No growth was observed in any treatment samples except the uncured control (4.31-log increase within 5 h; stage A). Phase 2 and 3 experiments were designed to investigate the effects of various nitrite and erythorbate concentrations and followed a 10-h stage A and 15-h stage B bilinear cooling profile. Phase 2 examined the effects of nitrite concentrations of 0, 50, 75, 100, 150, and 200 mg/kg at a constant concentration of erythorbate (547 mg/kg). Results revealed changes in C. perfringens populations for each treatment of 6.75, 3.59, 2.43, -0.38, -0.48, and -0.50 log CFU/g, respectively. Phase 3 examined the effects of various nitrite and erythorbate concentrations at 100 mg/kg nitrite with 0 mg/kg erythorbate, 100 with 250, 100 with 375, 100 with 547, 150 with 250, and 200 with 250, respectively. The changes in C. perfringens populations for each treatment were 4.99, 2.87, 2.50, 1.47, 0.89, and -0.60 log CFU/g, respectively. Variability in C. perfringens growth for the 100 mg/kg nitrite with 547 mg/kg erythorbate

  5. The reactivity of cesium nickel ferrocyanide towards nitrate and nitrite salts

    Energy Technology Data Exchange (ETDEWEB)

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

    1991-09-01

    Beginning in late 1988, the Pacific Northwest Laboratory (PNL) began an experimental program at the request of Westinghouse Hanford Company (WHC) to investigate the effects of temperature on the oxidation reaction between synthetic nickel cesium ferrocyanide (FeCN) and nitrates and nitrites representative of materials present in some of the Hanford single-shell tanks (SSTs). After completing a preliminary series of experiments in 1988, the program was expanded to include five tasks to evaluate the effect of selected compositional and operational parameters on the reaction and explosion temperatures of FeCN and nitrate and/or nitrite mixtures. 10 refs., 4 figs., 6 tabs.

  6. 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.

  7. 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....

  8. Reductive cleavage of nitrite to form terminal uranium mono-oxo complexes.

    Science.gov (United States)

    Lewis, Andrew J; Carroll, Patrick J; Schelter, Eric J

    2013-01-09

    Uranium terminal mono-oxo complexes are prepared with a unique activation of nitrite following reductive cleavage of an N-O bond with loss of nitric oxide. The thermodynamic driving force of U═O bond formation differentiates this reactivity from known mechanisms of nitrite reduction, which are typically mediated by proton transfer. Mechanistic details are explored by DFT supporting a simple homolytic cleavage pathway from a κ(1)-ONO bound intermediate. Complexes of the formula U(VI)OX[N(SiMe(3))(2)](3) are formed providing a trigonal bipyramidal framework into which ligands trans to the U═O bond may be installed.

  9. Analisa Perubahan Kandungan Nitrit (NO2-) dalam Rebusan Sayur Bayam Hijau dengan Metode Spektrofotometri

    OpenAIRE

    Manalu, Haposan

    2015-01-01

    The research has been carried out on the changing of nitrite (NO2-) content in a vegetable stew of green spinach. Vegetable spinach were obtained from Kebun Baru Village farmers, Kecamatan Hamparan Perak, Kabupaten Deli Serdang. Content of nitrite were determined at vegetable spinach and the water of boiled vegetable spinach using spectrophotometric methods. From the results of the research it was obtained with variations in time 0, 1, 2, 3, 4, and 5 hours were 4,159; 5,319; 7,239; 8,719; 10,...

  10. Calcium orthophosphates in dentistry.

    Science.gov (United States)

    Dorozhkin, Sergey V

    2013-06-01

    Dental caries, also known as tooth decay or a cavity, remains a major public health problem in the most communities even though the prevalence of disease has decreased since the introduction of fluorides for dental care. Therefore, biomaterials to fill dental defects appear to be necessary to fulfill customers' needs regarding the properties and the processing of the products. Bioceramics and glass-ceramics are widely used for these purposes, as dental inlays, onlays, veneers, crowns or bridges. Calcium orthophosphates belong to bioceramics but they have some specific advantages over other types of bioceramics due to a chemical similarity to the inorganic part of both human and mammalian bones and teeth. Therefore, calcium orthophosphates (both alone and as components of various formulations) are used in dentistry as both dental fillers and implantable scaffolds. This review provides brief information on calcium orthophosphates and describes in details current state-of-the-art on their applications in dentistry and dentistry-related fields. Among the recognized dental specialties, calcium orthophosphates are most frequently used in periodontics; however, the majority of the publications on calcium orthophosphates in dentistry are devoted to unspecified "dental" fields.

  11. 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.

  12. Impact of nitrite on aerobic phosphorus uptake by poly-phosphate accumulating organisms in enhanced biological phosphorus removal sludges.

    Science.gov (United States)

    Zeng, Wei; Li, Boxiao; Yang, Yingying; Wang, Xiangdong; Li, Lei; Peng, Yongzhen

    2014-02-01

    Impact of nitrite on aerobic phosphorus (P) uptake of poly-phosphate accumulating organisms (PAOs) in three different enhanced biological phosphorus removal (EBPR) systems was investigated, i.e., the enriched PAOs culture fed with synthetic wastewater, the two lab-scale sequencing batch reactors (SBRs) treating domestic wastewater for nutrient removal through nitrite-pathway nitritation and nitrate-pathway nitrification, respectively. Fluorescence in situ hybridization results showed that PAOs in the three sludges accounted for 72, 7.6 and 6.5% of bacteria, respectively. In the enriched PAOs culture, at free nitrous acid (FNA) concentration of 0.47 × 10(-3) mg HNO₂-N/L, aerobic P-uptake and oxidation of intercellular poly-β-hydroxyalkanoates were both inhibited. Denitrifying phosphorus removal under the aerobic conditions was observed, indicating the existence of PAOs using nitrite as electron acceptor in this culture. When the FNA concentration reached 2.25 × 10(-3) mg HNO2-N/L, denitrifying phosphorus removal was also inhibited. And the inhibition ceased once nitrite was exhausted. Corresponding to both SBRs treating domestic wastewater with nitritation and nitrification pathway, nitrite inhibition on aerobic P-uptake by PAOs did not occur even though FNA concentration reached 3 × 10(-3) and 2.13 × 10(-3) mg HNO₂-N/L, respectively. Therefore, PAOs taken from different EBPR activated sludges had different tolerance to nitrite.

  13. 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.

  14. 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

    Nitrite (NO2-) functions as an important nitric oxide (NO) donor under hypoxic conditions.Both nitrite and NO have been found to protect the mammalian heart and other tissues against ischemia(anoxia)-reoxygenation injury by interacting with mitochondrial electron transport complexes and limiting ...

  15. Investigating quality attributes and consumer acceptance of uncured, no-nitrate/nitrite-added commercial hams, bacons, and frankfurters.

    Science.gov (United States)

    Sindelar, J J; Cordray, J C; Olson, D G; Sebranek, J G; Love, J A

    2007-10-01

    Increasing demands for natural, organic, and/or preservative-free foods have resulted in the consumer availability of uncured, no-nitrate/nitrite-added processed meat and poultry products. A comprehensive understanding about the quality and sensory attributes of commercially available uncured products is unclear. The objective of this study was to determine if quality and sensory differences exist between uncured and cured meat products. Five different commercial brands (Brands A to E; 4 uncured, no-nitrate/nitrite-added, and 1 nitrite-added) of 3 product types (hams, frankfurters, and bacons) were obtained from retail supermarkets. The samples were evaluated for color, pigment content, pH, lipid oxidation, residual nitrate and nitrite content, and consumer acceptance. All brands from all product types evaluated, except for 1 bacon (Brand B), had cured color, aroma, and flavor attributes similar to the nitrite-added control (Brand E). All product types and brands contained residual nitrate and residual nitrite except for Brands B and D bacons (brands within each product type were similar to the control. Consumer sensory ratings for surface/lean color, aroma, flavor, texture, and overall acceptance determined that variation existed. Brand E (nitrite-added control) and 1 uncured, no-nitrate/nitrite-added brand for each product type were not different (P > 0.05) for overall acceptance and received higher scores (P brands within each product type.

  16. 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

  17. 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...

  18. Sustained release nitrite therapy results in myocardial protection in a porcine model of metabolic syndrome with peripheral vascular disease

    OpenAIRE

    Bradley, Jessica M.; Islam, Kazi N.; Polhemus, David J.; Donnarumma, Erminia; Brewster, Luke P.; Tao, Ya-Xiong; Goodchild, Traci T.; Lefer, David J.

    2015-01-01

    In a clinically relevant porcine model of metabolic syndrome and peripheral vascular disease, treatment with a novel sustained-release nitrite formulation restored cardiac endothelial nitric oxide synthase, enhancing myocardial nitrite levels, reduced oxidative stress, and improved ex vivo coronary vascular function via endothelium-independent vasodilation mechanism in obese Ossabaw swine.

  19. Polymeric membrane electrodes with high nitrite selectivity based on rhodium(III) porphyrins and salophens as ionophores.

    Science.gov (United States)

    Pietrzak, Mariusz; Meyerhoff, Mark E

    2009-05-01

    Several porphyrin and salophen complexes with Rh(III) are examined as ionophores to prepare nitrite selective polymeric membrane electrodes. All ionophores tested exhibit preferred selectivity toward nitrite anion. Enhanced potentiometric nitrite selectivity is observed in the presence of either lipophilic anionic as well as cationic sites within the membranes, suggesting that the ionophores can function via either a charged or a neutral carrier response mechanism. Among a range of complexes and membrane formulations examined, optimal nitrite selectivity and reversible response down to 5 x 10(-6) M is achieved using Rh(III)-tetra(t-butylphenylporphyrin) as the ionophore in the presence of lipophilic cationic sites in plasticized poly(vinyl chloride) membrane. Response times are substantially longer than typical membrane electrodes apparently because of a slow nitrite ligation reaction with Rh(III); however, a significant improvement in dynamic EMF response can be realized by optimizing the membrane formulation and increasing the temperature. The selectivity observed with these membranes is greater than the best nitrite selective electrodes reported to date in the literature based on lipophilic Co(III)-corrin complexes, allowing the new nitrite electrodes to be utilized to determine the level of nitrite in meats with good correlation to the colorimetric Griess assay method.

  20. Does amyl nitrite have a role in the management of pre-hospital mass casualty cyanide poisoning?

    Science.gov (United States)

    Lavon, Ophir; Bentur, Yedidia

    2010-07-01

    Amyl nitrite has been recommended as a cyanide antidote for several decades. Its antidotal properties were initially attributed to induction of methemoglobin and later to a nitric oxide mediated hemodynamic effect. The ease of administration and alleged rapid clinical effect would recommend its wide use in the pre-hospital management of mass casualty cyanide poisoning; yet there are concerns regarding the use of amyl nitrite for this indication. Review the data on amyl nitrite in cyanide poisoning and evaluate its efficacy and safety in mass casualty cyanide poisoning. A literature search utilizing PubMed, Toxnet, textbooks in toxicology and pharmacology, and the bibliographies of the articles retrieved identified 17 experimental studies and human reports on the use of amyl nitrite in cyanide poisoning, and 40 additional articles on amyl nitrite's properties and adverse effects. One paper was excluded as it was a conference abstract with limited data. The antidotal properties of amyl nitrite were attributed initially to induction of methemoglobinemia and later to nitric oxide mediated vasodilation. Animal studies on the use of amyl nitrite in cyanide poisoning are limited, and their results are inconsistent, which makes their extrapolation to humans questionable. Clinical reports are limited in number and the part played by amyl nitrite relative to the other treatments administered (e.g. life support, sodium nitrite, and sodium thiosulfate) is unclear. Amyl nitrite can be associated with potentially serious adverse reactions such as hypotension, syncope, excessive methemoglobinemia, and hemolysis in G6PD deficient patients. These effects are more pronounced in young children, in the elderly, and in patients with cardiac and pulmonary disorders. Dose regimen. The method of administration of amyl nitrite (breaking pearls into gauze or a handkerchief and applying it intermittently to the victim's nose and mouth for a few minutes) is not easily controlled, might result

  1. Differential abilities of nitrogen dioxide and nitrite to nitrate proteins in thylakoid membranes isolated from Arabidopsis leaves.

    Science.gov (United States)

    Takahashi, Misa; Shigeto, Jun; Shibata, Tatsuo; Sakamoto, Atsushi; Morikawa, Hiromichi

    2016-10-02

    Exposure of Arabidopsis leaves to nitrogen dioxide (NO2) results in nitration of specific chloroplast proteins. To determine whether NO2 itself and/or nitrite derived from NO2 can nitrate proteins, Arabidopsis thylakoid membranes were isolated and treated with NO2-bubbled or potassium nitrite (KNO2) buffer, followed by protein extraction, electrophoresis, and immunoblotting using an anti-3-nitrotyrosine (NT) antibody. NO2 concentrations in the NO2-bubbled buffer were calculated by numerically solving NO2 dissociation kinetic equations. The two buffers were adjusted to have identical nitrite concentrations. Both treatments yielded an NT-immunopositive band that LC/MS identified as PSBO1. The difference in the band intensity between the 2 treatments was designated nitration by NO2. Both NO2 and nitrite mediated nitration of proteins, and the nitration ability per unit NO2 concentration was ∼100-fold greater than that of nitrite.

  2. Current perspectives and challenges in understanding the role of nitrite as an integral player in nitric oxide biology and therapy.

    Science.gov (United States)

    Vitturi, Dario A; Patel, Rakesh P

    2011-08-15

    Beyond an inert oxidation product of nitric oxide (NO) metabolism, current thinking posits a key role for nitrite as a mediator of NO signaling, especially during hypoxia. This concept has been discussed in the context of nitrite serving a role as an endogenous modulator of NO homeostasis, but also from a novel clinical perspective whereby nitrite therapy may replenish NO signaling and prevent ischemic tissue injury. Indeed, the relatively rapid translation of studies delineating mechanisms of action to ongoing and planned clinical trials has been critical in fuelling interest in nitrite biology, and several excellent reviews have been written on this topic. In this article we limit our discussions to current concepts and what we feel are questions that remain unanswered within the paradigm of nitrite being a mediator of NO biology. Copyright © 2011 Elsevier Inc. All rights reserved.

  3. Calcium Signalling: Fishing Out Molecules of Mitochondrial Calcium Transport

    OpenAIRE

    Hajnóczky, György; Csordás, György

    2010-01-01

    Cellular energy metabolism, survival and death are controlled by mitochondrial calcium signals originating in the cytoplasm. Now, RNAi studies link three proteins — MICU1, NCLX and LETM1 — to the previously unknown molecular mechanism of mitochondrial calcium transport.

  4. Gravimetric Determination of Calcium as Calcium Carbonate Hydrate.

    Science.gov (United States)

    Henrickson, Charles H.; Robinson, Paul R.

    1979-01-01

    The gravimetric determination of calcium as calcium carbonate is described. This experiment is suitable for undergraduate quantitative analysis laboratories. It is less expensive than determination of chloride as silver chloride. (BB)

  5. Implications of Decreased Nitrite Concentrations on Clostridium perfringens Outgrowth during Cooling of Ready-to-Eat Meats.

    Science.gov (United States)

    Myers, Megan I; Sebranek, Joseph G; Dickson, James S; Shaw, Angela M; Tarté, Rodrigo; Adams, Kristin R; Neibuhr, Steve

    2016-01-01

    Increased popularity of natural and organic processed meats can be attributed to the growing consumer demand for preservative-free foods, including processed meats. To meet this consumer demand, meat processors have begun using celery juice concentrate in place of sodium nitrite to create products labeled as no-nitrate or no-nitrite-added meat products while maintaining the characteristics unique to conventionally cured processed meats. Because of flavor limitations, natural cures with celery concentrate typically provide lower ingoing nitrite concentrations for ready-to-eat processed meats than do conventional cures, which could allow for increased growth of pathogens, such as Clostridium perfringens, during cooked product cooling such as that required by the U.S. Department of Agriculture. The objective of this study was to investigate the implications associated with reduced nitrite concentrations for preventing C. perfringens outgrowth during a typical cooling cycle used for cooked products. Nitrite treatments of 0, 50, and 100 ppm were tested in a broth system inoculated with a three-strain C. perfringens cocktail and heated with a simulated product thermal process followed by a typical cooling-stabilization process. The nitrite concentration of 50 ppm was more effective for preventing C. perfringens outgrowth than was 0 ppm but was not as effective as 100 ppm. The interaction between nitrite and temperature significantly affected (P perfringens outgrowth in both total population and number of vegetative cells. Both temperature and nitrite concentration significantly affected (P perfringens spore survival, but the interaction between nitrite and temperature did not have a significant effect (P > 0.05) on spore outgrowth. Results indicate that decreased nitrite concentrations (50 ppm) have increased potential for total C. perfringens population outgrowth during cooling and may require additional protective measures, such as faster chilling rates.

  6. 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

  7. Draft Genome Sequence of Nitrobacter vulgaris Strain Ab1, a Nitrite-Oxidizing Bacterium.

    Science.gov (United States)

    Mellbye, Brett L; Davis, Edward W; Spieck, Eva; Chang, Jeff H; Bottomley, Peter J; Sayavedra-Soto, Luis A

    2017-05-04

    Here, we present the 3.9-Mb draft genome sequence of Nitrobacter vulgaris strain Ab1, which was isolated from a sewage system in Hamburg, Germany. The analysis of its genome sequence will contribute to our knowledge of nitrite-oxidizing bacteria and acyl-homoserine lactone quorum sensing in nitrifying bacteria. Copyright © 2017 Mellbye et al.

  8. Draft Genome Sequence of Nitrobacter vulgaris Strain Ab1, a Nitrite-Oxidizing Bacterium

    OpenAIRE

    Brett L. Mellbye; Davis, Edward W.; Spieck, Eva; Jeff H Chang; Bottomley, Peter J.; Sayavedra-Soto, Luis A.

    2017-01-01

    ABSTRACT Here, we present the 3.9-Mb draft genome sequence of Nitrobacter vulgaris strain Ab1, which was isolated from a sewage system in Hamburg, Germany. The analysis of its genome sequence will contribute to our knowledge of nitrite-oxidizing bacteria and acyl-homoserine lactone quorum sensing in nitrifying bacteria.

  9. Carbon nano-fiber based membrane reactor for selective nitrite hydrogenation

    NARCIS (Netherlands)

    Brunet Espinosa, Roger; Rafieian, D.; Lammertink, Rob G.H.; Lefferts, Leonardus

    2016-01-01

    Catalytic hydrogenation of nitrite in drinking water demands control over the selectivity towards nitrogen, minimizing the formation of ammonia. This selectivity is strongly influenced by the H/N ratio of reaction intermediates at the catalyst surface. Therefore, we fabricated a membrane reactor

  10. 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

    by using moving bed bio-elements from a freshwater RAS in steady state operated at 18 °C. The impact of temperature on ammonium and nitrite oxidation rates was evaluated by transferring the colonized bio elements to six liter batch reactors (triplicated setup). Each reactor was acclimatized for 24 h...

  11. 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

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

    African Journals Online (AJOL)

    Michael Horsfall

    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 ...

  13. Calorimetric and spectroscopic investigations of the thermal denaturation of wild type nitrite reductase

    NARCIS (Netherlands)

    Stirpe, A; Guzzi, R; Wijma, H; Verbeet, MP; Canters, GW; Sportelli, L

    2005-01-01

    Nitrite reductase (NiR) is a multicopper protein, with a trimeric structure containing two types of copper site: type I is present in each subunit whereas type 2 is localized at the subunits interface. The paper reports on the thermal behaviour of wild type NiR from Alcaligenes faecalis S-6. The

  14. Reduced iron associated with secondary nitrite maxima in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Moffetta, J.W.; Goepferta, T.J.; Naqvi, S.W.A.

    Dissolved iron and Fe(II) were measured in the oxygen minimum zone (OMZ) of the Arabian Sea in September 2004. The OMZ is a well-demarcated feature characterized by high rates of denitrification, and a deep nitrite maximum coinciding with oxygen...

  15. Full-scale partial nitritation/anammox experiences : An application survey

    NARCIS (Netherlands)

    Lackner, S.; Gilbert, E.M.; Vlaeminck, S.E.; Joss, A.; Horn, H.; Van Loosdrecht, M.C.M.

    2014-01-01

    Partial nitritation/anammox (PN/A) has been one of the most innovative developments in biological wastewater treatment in recent years. With its discovery in the 1990s a completely new way of ammonium removal from wastewater became available. Over the past decade many technologies have been

  16. 21 CFR 170.60 - Nitrites and/or nitrates in curing premixes.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Nitrites and/or nitrates in curing premixes. 170.60 Section 170.60 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... oils, disodium inosinate, disodium guanylate, hydrolysates of animal or plant origin (such as...

  17. 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

  18. Photolysis of Nitrate and Nitrite in Artificial Snow and Artificial Ice

    Science.gov (United States)

    Shi, W.; Green, S. A.

    2003-12-01

    It is well known that nitrate and nitrite undergo photolysis in aqueous solution. Recent studies show that these reactions are likely to occur in natural snow as well. Therefore it is of interest to measure rates of photolysis of nitrate and nitrite in snow and ice. In this study artificial snow was made by spraying a solution onto the wall of a reservoir containing liquid nitrogen. Artificial snow and ice were irradiated in a sealed quartz tube with a UV lamp and production of hydroxyl radicals was quantified. Hydroxyl radicals produced in these processes react with dimethyl sulfoxide to release methyl radicals, which were trapped by 3-amino-2,2,5,5-tetramethyl-1-pyrrolidinyloxy free radical (3AP). The 3AP-CH3 compound was later derivatized to produce a highly fluorescent adduct, which was measured by HPLC. Snow produced the highest yield of hydroxyl radicals and ice the lowest. Nitrite had higher yield than nitrate. The calculation of photolysis rates for nitrate and nitrite in snow and ice is discussed.

  19. An Assessment of the Levels of Heavy Metals, Nitrates and Nitrites ...

    African Journals Online (AJOL)

    kg and was within the safe limit (< 3.70 mg/kg) as recommended by (FAO)/WHO Expert Committee on food additives while nitrite was not detected. In conclusion, monitoring of vegetables for toxic heavy metals is essential for food safety in ...

  20. analysis of nitrates and nitrit es in subsoil and ground water samples ...

    African Journals Online (AJOL)

    2004-08-08

    ANALYSIS OF NITRATES AND NITRIT ES IN SUBSOIL AND GROUND WATER. SAMPLES IN SWAZILAND. A.O. Fadiran: W.F. Mdlulie and BK. Simelane. Department of Chemistry, University of Swaziland, P/Bag 4, Kwaluseni, Swaziland. (Received August 8, 2004; revised October 4, 2004). ABSTRACT. The concentrations ...

  1. 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.

  2. 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...

  3. 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...... for a few samples back in 2002. The intake, mean and intake distribution of sodium nitrite have been calculated from 1998 to 2006 with data from the Danish dietary survey conducted in 2000-02 on Danes from four to 75 years of age. The amounts used by industry have been relatively stable through the whole...

  4. 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.

  5. A Comparison of the Treatment of Cyanide Poisoning in the Cynomolgus Monkey with Sodium Nitrite of 4-Dimethylaminophenol (4-DMAP), with and without Sodium Thiosulfate

    Science.gov (United States)

    1994-02-01

    Chen et al, 1934), amyl nitrite (Pedigo, 1888; Chen et al, 1933; Klimmek et a, 1988 a and b; Paulet, 1954), sodium nitrite (Hug and Marenzi , 1933; Chen...nitrite de sodium et du sulfure de sodium. Comp. Rend. Soc. Biol. Ses FRI. 111, 89-90. Hug, E., and Marenzi , A.D. (1933). Mecanisme de r’action

  6. Children's Bone Health and Calcium

    Science.gov (United States)

    ... Email Share Dialog × 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 ...

  7. Using saliva nitrite and nitrate levels as a biomarker for drug induced gingival overgrowth

    Directory of Open Access Journals (Sweden)

    Erkan eSukuroglu

    2015-12-01

    Full Text Available Aim: Drug-induced gingival overgrowth has a multifactorial nature and the pathogenesis is still uncertain. It has been suggested that Nitric Oxide (NO might play a role in the pathogenesis of drug-induced gingival overgrowth due to the contribution of NO to immune response and matrix degradation. NO levels in biological fluids have been used as a diagnostic biomarker in many diseases. The aim of this study is to determine whether NO levels in plasma, saliva and gingival crevicular fluid (GCF can serve as a potential biomarker for the evaluation of drug-induced gingival overgrowth risk. Material and Methods: A total of 104 patients, receiving cyclosporine A (n=35, phenytoin (n=25, nifedipine (n=26 or diltiazem (n=18 participated in the study. The amount of gingival overgrowth was evaluated with two indices and was given as percentage. Periodontal clinical parameters including plaque index (PI, gingival index (GI, gingival bleeding time index (GBTI and probing depth (PD were also assessed. Saliva, GCF and plasma samples were obtained from each participants. Nitrite and nitrate levels in saliva, GCF and plasma were analyzed by Griess reagent. Results: Salivary nitrite and nitrate levels in responders were significantly higher than those in non-responders in only phenytoin group (p˂0.05. Nitrite and nitrate levels of gingival crevicular fluid and plasma did not significantly differ between responders and non-responders in all study groups (p˃0.05. Salivary nitrite levels exhibited a significant correlation with PD, GBTI, severity of gingival overgrowth (%GO and GCF volume (p˂0.05. Additionally, a strong positive correlation was detected between saliva and plasma nitrate levels (p˂0.005. However, both nitrite and nitrate levels in GCF and plasma demonstrated no significant correlation with clinical parameters, GO severity and GCF volume (p˃0.05.Conclusion: Salivary nitrite and nitrate levels could be used as periodontal disease biomarkers in

  8. Stable prenucleation calcium carbonate clusters

    OpenAIRE

    Gebauer, Denis; Völkel, Antje; Cölfen, Helmut

    2008-01-01

    Calcium carbonate forms scales, geological deposits, biominerals, and ocean sediments. Huge amounts of carbon dioxide are retained as carbonate ions, and calcium ions represent a major contribution to water hardness. Despite its relevance, little is known about the precipitation mechanism of calcium carbonate, and specified complex crystal structures challenge the classical view on nucleation considering the formation of metastable ion clusters. We demonstrate that dissolved calcium carbonate...

  9. Assay for calcium channels

    Energy Technology Data Exchange (ETDEWEB)

    Glossmann, H.; Ferry, D.R.

    1985-01-01

    This chapter focuses on biochemical assays for Ca/sup 2 +/-selective channels in electrically excitable membranes which are blocked in electrophysiological and pharmacological experiments by verapamil, 1,4-dihydropyridines, diltiazen (and various other drugs), as well as inorganic di- or trivalent cations. The strategy employed is to use radiolabeled 1,4-dihydropyridine derivatives which block calcium channels with ED/sub 50/ values in the nanomolar range. Although tritiated d-cis-diltiazem and verapamil can be used to label calcium channels, the 1,4-dihydropyridines offer numerous advantages. The various sections cover tissue specificity of channel labeling, the complex interactions of divalent cations with the (/sup 3/H)nimodipine-labeled calcium channels, and the allosteric regulation of (/sup 3/H)nimodipine binding by the optically pure enantiomers of phenylalkylamine and benzothiazepine calcium channel blockers. A comparison of the properties of different tritiated 1,4-dihydropyridine radioligands and the iodinated channel probe (/sup 125/I)iodipine is given.

  10. 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...

  11. The genome of Nitrospina gracilis illuminates the metabolism and evolution of the major marine nitrite oxidizer

    Directory of Open Access Journals (Sweden)

    Sebastian eLuecker

    2013-02-01

    Full Text Available In marine systems, nitrate is the major reservoir of inorganic fixed nitrogen. The only known biological nitrate-forming reaction is nitrite oxidation, but despite its importance, our knowledge of the organisms catalyzing this key process in the marine N-cycle is very limited. The most frequently encountered marine NOB are related to Nitrospina gracilis, an aerobic chemolithoautotrophic bacterium isolated from ocean surface waters. To date, limited physiological and genomic data for this organism were available and its phylogenetic affiliation was uncertain. In this study, the draft genome sequence of Nitrospina gracilis strain 3/211 was obtained. Unexpectedly for an aerobic organism, N. gracilis lacks classical reactive oxygen defense mechanisms and uses the reductive tricarboxylic acid cycle for carbon fixation. These features indicate microaerophilic ancestry and are consistent with the presence of Nitrospina in marine oxygen minimum zones. Fixed carbon is stored intracellularly as glycogen, but genes for utilizing external organic carbon sources were not identified. N. gracilis also contains a full gene set for oxidative phosphorylation with oxygen as terminal electron acceptor and for reverse electron transport from nitrite to NADH. A novel variation of complex I may catalyze the required reverse electron flow to low-potential ferredoxin. Interestingly, comparative genomics indicated a strong evolutionary link between Nitrospina, the nitrite-oxidizing genus Nitrospira, and anaerobic ammonium oxidizers, apparently including the horizontal transfer of a periplasmically oriented nitrite oxidoreductase and other key genes for nitrite oxidation at an early evolutionary stage. Further, detailed phylogenetic analyses using concatenated marker genes provided evidence that Nitrospina forms a novel bacterial phylum, for which we propose the name Nitrospinae.

  12. Zn-porphyrin formation in cured meat products: Effect of added salt and nitrite.

    Science.gov (United States)

    Adamsen, Christina E; Møller, Jens K S; Laursen, Kristoffer; Olsen, Karsten; Skibsted, Leif H

    2006-04-01

    Zn-porphyrin (Zn-pp) was quantified by fluorescence spectroscopy in the cured and dry cured meat products: Parma ham, Iberian ham, dry-cured ham with added nitrite, cooked ham with added nitrite, raw ham meat, raw bacon and Karree-Speck. The highest amount of Zn-pp was found in dry-cured Parma ham and Iberian ham, while the use of nitrite as curing agent was found to inhibit completely the formation of Zn-pp in meat products. A positive correlation between both Zn content and Fe content and the logarithmic transformed Zn-pp content (measured as fluorescence intensity I(fl)) was found for the different cured and dry cured meat products, with correlation coefficients of 0.79 (p<0.001) and 0.71 (p<0.01), respectively. Log I(fl) correlates best with the Zn content, indicating that the formation of Zn-pp is proportional to the Zn content. A model system with vacuum packed pork in brine with different added levels of sodium chloride with or without nitrite and Zn acetate was investigated in order to further elucidate the mechanism of Zn-pp formation. Zn-pp increased with time (up to 42 days investigated) in non-cured meat and for meat cured solely with NaCl lower than 9%. Addition of nitrite or Zn(II) in the curing brine was found to inhibit formation of Zn-pp confirming the observations from the various cured meat products. It is suggested that a chloride anion assisted dissociation of iron from myoglobin could be rate-determining for Zn-pp formation in meat products.

  13. 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.

  14. Genome sequence of the chemolithoautotrophic nitrite-oxidizing bacterium Nitrobacter winogradskyi Nb-255

    Energy Technology Data Exchange (ETDEWEB)

    Hauser, Loren John [ORNL; Land, Miriam L [ORNL; Larimer, Frank W [ORNL; Arp, D J [Oregon State University; Hickey, W J [University of Wisconsin, Madison

    2006-03-01

    The alphaproteobacterium Nitrobacter winogradskyi (ATCC 25391) is a gram-negative facultative chemolithoautotroph capable of extracting energy from the oxidation of nitrite to nitrate. Sequencing and analysis of its genome revealed a single circular chromosome of 3,402,093 bp encoding 3,143 predicted proteins. There were extensive similarities to genes in two alphaproteobacteria, Bradyrhizobium japonicum USDA110 (1,300 genes) and Rhodopseudomonas palustris CGA009 CG (815 genes). Genes encoding pathways for known modes of chemolithotrophic and chemoorganotrophic growth were identified. Genes encoding multiple enzymes involved in anapleurotic reactions centered on C2 to C4 metabolism, including a glyoxylate bypass, were annotated. The inability of N. winogradskyi to grow on C6 molecules is consistent with the genome sequence, which lacks genes for complete Embden-Meyerhof and Entner-Doudoroff pathways, and active uptake of sugars. Two gene copies of the nitrite oxidoreductase, type I ribulose-1,5-bisphosphate carboxylase/oxygenase, cytochrome c oxidase, and gene homologs encoding an aerobic-type carbon monoxide dehydrogenase were present. Similarity of nitrite oxidoreductases to respiratory nitrate reductases was confirmed. Approximately 10% of the N. winogradskyi genome codes for genes involved in transport and secretion, including the presence of transporters for various organic-nitrogen molecules. The N. winogradskyi genome provides new insight into the phylogenetic identity and physiological capabilities of nitrite-oxidizing bacteria. The genome will serve as a model to study the cellular and molecular processes that control nitrite oxidation and its interaction with other nitrogen-cycling processes.

  15. Genome sequence of the chemolithoautotrophic nitrite-oxidizing bacterium Nitrobacter winogradskyi Nb-255.

    Science.gov (United States)

    Starkenburg, Shawn R; Chain, Patrick S G; Sayavedra-Soto, Luis A; Hauser, Loren; Land, Miriam L; Larimer, Frank W; Malfatti, Stephanie A; Klotz, Martin G; Bottomley, Peter J; Arp, Daniel J; Hickey, William J

    2006-03-01

    The alphaproteobacterium Nitrobacter winogradskyi (ATCC 25391) is a gram-negative facultative chemolithoautotroph capable of extracting energy from the oxidation of nitrite to nitrate. Sequencing and analysis of its genome revealed a single circular chromosome of 3,402,093 bp encoding 3,143 predicted proteins. There were extensive similarities to genes in two alphaproteobacteria, Bradyrhizobium japonicum USDA110 (1,300 genes) and Rhodopseudomonas palustris CGA009 CG (815 genes). Genes encoding pathways for known modes of chemolithotrophic and chemoorganotrophic growth were identified. Genes encoding multiple enzymes involved in anapleurotic reactions centered on C2 to C4 metabolism, including a glyoxylate bypass, were annotated. The inability of N. winogradskyi to grow on C6 molecules is consistent with the genome sequence, which lacks genes for complete Embden-Meyerhof and Entner-Doudoroff pathways, and active uptake of sugars. Two gene copies of the nitrite oxidoreductase, type I ribulose-1,5-bisphosphate carboxylase/oxygenase, cytochrome c oxidase, and gene homologs encoding an aerobic-type carbon monoxide dehydrogenase were present. Similarity of nitrite oxidoreductases to respiratory nitrate reductases was confirmed. Approximately 10% of the N. winogradskyi genome codes for genes involved in transport and secretion, including the presence of transporters for various organic-nitrogen molecules. The N. winogradskyi genome provides new insight into the phylogenetic identity and physiological capabilities of nitrite-oxidizing bacteria. The genome will serve as a model to study the cellular and molecular processes that control nitrite oxidation and its interaction with other nitrogen-cycling processes.

  16. 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.

  17. Nitrogen isotope fractionation during archaeal ammonia oxidation: Coupled estimates from isotopic measurements of ammonium and nitrite

    Science.gov (United States)

    Mooshammer, Maria; Stieglmeier, Michaela; Bayer, Barbara; Jochum, Lara; Melcher, Michael; Wanek, Wolfgang

    2014-05-01

    Ammonia-oxidizing archaea (AOA) are ubiquitous in marine and terrestrial environments and knowledge about the nitrogen (N) isotope effect associated with their ammonia oxidation activity will allow a better understanding of natural abundance isotope ratios, and therefore N transformation processes, in the environment. Here we examine the kinetic isotope effect for ammonia oxidation in a pure soil AOA culture (Ca. Nitrososphaera viennensis) and a marine AOA enrichment culture. We estimated the isotope effect from both isotopic signatures of ammonium and nitrite over the course of ammonia oxidation. Estimates of the isotope effect based on the change in the isotopic signature of ammonium give valuable insight, because these estimates are not subject to the same concerns (e.g., accumulation of an intermediate) as estimates based on isotopic measurements of nitrite. Our results show that both the pure soil AOA culture and a marine AOA enrichment culture have similar but substantial isotope effect during ammonia consumption (31-34 per mill; based on ammonium) and nitrite production (43-45 per mill; based on nitrite). The 15N fractionation factors of both cultures tested fell in the upper range of the reported isotope effects for archaeal and bacterial ammonia oxidation (10-41 per mill) or were even higher than those. The isotope fractionation for nitrite production was significantly larger than for ammonium consumption, indicating that (1) some intermediate (e.g., hydroxylamine) of ammonia oxidation accumulates, allowing for a second 15N fractionation step to be expressed, (2) a fraction of ammonia oxidized is lost via gaseous N forms (e.g., NO or N2O), which is 15N-enriched or (3) a fraction of ammonium is assimilated into AOA biomass, biomass becoming 15N-enriched. The significance of these mechanisms will be explored in more detail for the soil AOA culture, based on isotope modeling and isotopic measurements of biomass and N2O.

  18. Kinetic Constants for Biological Ammonium and Nitrite Oxidation Processes Under Sulfide Inhibition.

    Science.gov (United States)

    Bejarano-Ortiz, Diego Iván; Huerta-Ochoa, Sergio; Thalasso, Frédéric; Cuervo-López, Flor de María; Texier, Anne-Claire

    2015-12-01

    Inhibition of nitrification by sulfide was assessed using sludge obtained from a steady-state nitrifying reactor. Independent batch activity assays were performed with ammonium and nitrite as substrate, in order to discriminate the effect of sulfide on ammonium and nitrite oxidation. In the absence of sulfide, substrate affinity constants (K S,NH4  = 2.41 ± 0.11 mg N/L; K s, NO2  = 0.74 ± 0.03 mg N/L) and maximum specific rates (q max,NH4  = 0.086 ± 0.008 mg N/mg microbial protein h; q max,NO2  = 0.124 ± 0.001 mg N/mg microbial protein h) were determined. Inhibition of ammonium oxidation was no-competitive (inhibition constant (K i , NH4 ) of 2.54 ± 0.12 mg HS(-)-S/L) while inhibition of nitrite oxidation was mixed (competitive inhibition constant (K' i , NO2 ) of 0.22 ± 0.03 mg HS(-)-S/L and no-competitive inhibition constant (K i , NO2 ) of 1.03 ± 0.06 mg HS(-)-S/L). Sulfide has greater inhibitory effect on nitrite oxidation than ammonium oxidation, and its presence in nitrification systems should be avoided to prevent accumulation of nitrite. By simulating the effect of sulfide addition in a continuous nitrifying reactor under steady-state operation, it was shown that the maximum sulfide concentration that the sludge can tolerate without affecting the ammonium consumption efficiency and nitrate yield is 1 mg HS(-)-S/L.

  19. 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.

  20. Combined exposure to ambient UVB radiation and nitrite negatively affects survival of amphibian early life stages.

    Science.gov (United States)

    Macías, Guadalupe; Marco, Adolfo; Blaustein, Andrew R

    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.

  1. Polyethylene glycol conjugation enhances the nitrite reductase activity of native and cross-linked hemoglobin.

    Science.gov (United States)

    Lui, Francine E; Dong, Pengcheng; Kluger, Ronald

    2008-10-07

    Although stabilized hemoglobins have been evaluated as oxygen-carrying replacements for red cells in transfusions, in vivo evaluations have noted that these materials are associated with vasoactivity, a serious complication. Scavenging of endogenous nitric oxide by the deoxyheme sites of the stabilized proteins is one likely source of vasoactivity. Recent reports indicate that modification of cell-free hemoglobin derivatives with multiple chains of polyethylene glycol (PEG) suppresses vasoactivity. Gladwin and co-workers observed that the nitrite reductase activity of hemoglobin serves as a major endogenous source of nitric oxide. If PEG conjugation leads to enhanced nitrite reductase activity, this could compensate for scavenged endogenous nitric oxide. To test this possibility, the rates of conversion of nitrite ion to nitric oxide by altered hemoglobins with and without PEG were measured at 25 degrees C. Fumaryl (alpha99-alpha99) cross-linked hemoglobin reacts with nitrite with a bimolecular rate constant of 0.52 M (-1) s (-1), which is comparable to that associated with native hemoglobin (0.25 M (-1) s (-1)). Addition of PEG chains to the cross-linked hemoglobin at beta-Cys93 (alphaalpha-Hb-PEG5K 2) results in a material that produces nitric oxide much more rapidly ( k = 1.41 M (-1) s (-1)). R-State-stabilized hemoglobins with multiple PEG chains (Hb-PEG5K 2 and Hb-PEG5K 6) react 10 times faster with nitrite to produce nitric oxide than does native hemoglobin ( k = 2.5 and 2.4 M (-1) s (-1), respectively). These results, showing enhanced production of nitric oxide resulting from an increased proportion of the protein residing in the R-state, are consistent with the decrease in vasoactivity associated with PEG conjugation.

  2. Dietary nitrite supplementation attenuates cardiac remodeling in l-NAME-induced hypertensive rats.

    Science.gov (United States)

    Sonoda, Kunihiro; Ohtake, Kazuo; Uchida, Hiroyuki; Ito, Junta; Uchida, Masaki; Natsume, Hideshi; Tamada, Hazuki; Kobayashi, Jun

    2017-07-01

    Loss of nitric oxide (NO) bioavailability underlies the development of hypertensive heart disease. We investigated the effects of dietary nitrite on N(G)-nitro-l-arginine methyl ester (l-NAME)-induced hypertension. Sprague-Dawley rats were divided into five groups: an untreated control group, an l-NAME-treated group, and three other l-NAME-treated groups supplemented with 10 mg/L or 100 mg/L of nitrite or 100 mg/L of captopril in drinking water. After the 8-week experimental period, mean arterial blood pressure was measured, followed by sampling of blood and heart tissue for assessment of nitrite/nitrate levels in the plasma and heart, the plasma level of angiotensin II (AT II), and the heart transcriptional levels of AT II type 1 receptor (AT1R), transforming growth factor-β1 (TGF-β1), and connective tissue proteins such as type 1 collagen and fibronectin. Heart tissue was analyzed by histopathological morphometry, including assessments of ventricular and coronary vascular hypertrophy and fibrosis, as well as immunohistochemistry analyses of myocardial expression of AT1R. l-NAME treatment reduced the plasma nitrate level and led to the development of hypertension, with increased plasma levels of AT II and increased heart transcriptional levels of AT1R and TGF-β1-mediated connective tissue proteins, showing myocardial and coronary arteriolar hypertrophy and fibrosis. However, dietary nitrite supplementation inhibited TGF-β1-mediated cardiac remodeling by suppressing AT II and AT1R. These results suggest that dietary nitrite levels achievable via a daily high-vegetable diet could improve hypertensive heart disease by inhibiting AT II-AT1R-mediated cardiac remodeling. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. The acid-catalyzed interaction of melanin with nitrite ions. An EPR investigation

    Directory of Open Access Journals (Sweden)

    Matuszak Zenon

    2015-07-01

    Full Text Available The interaction of synthetic dihydroxyphenylalanine (DOPA melanin (DM with nitrite ions, NO2−, in the pH 3.6–7.0 range, has been investigated using electron paramagnetic resonance (EPR. We found that especially at pH <5.5 (from ca. 5.5 to 3.6 the reaction of DM with nitrite generated large quantities of new melanin radicals, which implies the involvement of nitrous acid, HNO2, in the radical formation process. Measurements carried out at constant pH of 3.6 showed that the melanin signal increased together with nitrite concentration, reaching a plateau level which was more than fourfold larger compared to the initial signal amplitude observed in a nitrite-free buffer of the same pH. The effects of nitrite and DM concentrations on the melanin-free radical content were also investigated. It is proposed that the radicals are generated by one electron oxidation of melanin ortho-hydroquinone groups to ortho-semiquinones by HNO2 or related nitrogen oxides such as NO2• radicals. The possible involvement of nitric oxide (•NO and peroxynitrite (ONOO− in DM oxidation was also examined. In air-free solutions, nitric oxide per se did not generate melanin radicals; however, in the presence of oxygen a marked increase in the melanin EPR signal intensity was observed. This result is interpreted in terms of the generation of radicals via the oxidation of DM by peroxynitrite. Our findings suggest that melanin can function as a natural scavenger of nitrous acid and some nitrous acid-derived species. This property may be relevant to physiological functions of melanin pigments in vivo.

  4. PLASMA NITRITE FLUX PREDICTS EXERCISE PERFORMANCE IN PERIPHERAL ARTERIAL DISEASE FOLLOWING 3 MONTHS OF EXERCISE TRAINING

    Science.gov (United States)

    Allen, Jason D; Stabler, Thomas; Kenjale, Aarti; Ham, Katherine L.; Robbins, Jennifer.L.; Duscha, Brian D; Dobrosielski, Devon A; Annex, Brian H

    2010-01-01

    Plasma nitrite is a major oxidation product of nitric oxide. It has also recently been suggested to perform an endocrine-like function as a nitric oxide donor in hypoxic tissues, allowing vasodilation. Exercise performance is limited in peripheral arterial disease due to an inadequate blood supply to working tissues. We hypothesized that exercise training in peripheral arterial disease subjects will demonstrate improved “plasma nitrite flux” and endothelial function, to accompany increased exercise performance. Peripheral arterial disease subjects were tested at baseline and following 3 months supervised or home exercise training. Venous blood (arm) was drawn at rest and 10min following a maximal graded treadmill test. Samples were added to heparin, centrifuged and plasma snap frozen for analysis by reductive chemiluminescence. Brachial artery endothelial function was measured in response to a hyperemic stimulus (flow-mediated dilation). At 3 months the peripheral arterial disease-supervised exercise group showed increases in claudication onset pain time (+138sec, p≤0.05) peak walking time (+260sec, p≤0.01), VO2peak (1.3ml/kg/min, p≤0.05), brachial artery flow-mediated dilation (+2%, p≤0.05) and plasma nitrite flux (+33% p≤0.05). There were no changes in the peripheral arterial disease-home exercise group. The change in plasma nitrite flux predicted the change in claudication onset pain (r2=0.59, p≤0.01). These findings suggest changes in plasma nitrite are related to endothelial function and predict exercise performance in peripheral arterial disease. PMID:20620208

  5. 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.

  6. 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 (HRp95vs. Q1  = 1.16, 95% CI: 0.51-2.64). Associations with average TTHM levels were also null (HRQ4vs. 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 (HRp95vs. Q1  = 1.66, 95% CI 1.00-2.75;ptrend  = 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.

  7. 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

  8. 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.

  9. 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...

  10. Impregnating Coal With Calcium Carbonate

    Science.gov (United States)

    Sharma, Pramod K.; Voecks, Gerald E.; Gavalas, George R.

    1991-01-01

    Relatively inexpensive process proposed for impregnating coal with calcium carbonate to increase rates of gasification and combustion of coal and to reduce emission of sulfur by trapping sulfur in calcium sulfide. Process involves aqueous-phase reactions between carbon dioxide (contained within pore network of coal) and calcium acetate. Coal impregnated with CO2 by exposing it to CO2 at high pressure.

  11. Gastric S-nitrosothiol formation drives the antihypertensive effects of oral sodium nitrite and nitrate in a rat model of renovascular hypertension.

    Science.gov (United States)

    Pinheiro, Lucas C; Amaral, Jefferson H; Ferreira, Graziele C; Portella, Rafael L; Ceron, Carla S; Montenegro, Marcelo F; Toledo, Jose Carlos; Tanus-Santos, Jose E

    2015-10-01

    Many effects of nitrite and nitrate are attributed to increased circulating concentrations of nitrite, ultimately converted into nitric oxide (NO(•)) in the circulation or in tissues by mechanisms associated with nitrite reductase activity. However, nitrite generates NO(•) , nitrous anhydride, and other nitrosating species at low pH, and these reactions promote S-nitrosothiol formation when nitrites are in the stomach. We hypothesized that the antihypertensive effects of orally administered nitrite or nitrate involve the formation of S-nitrosothiols, and that those effects depend on gastric pH. The chronic effects of oral nitrite or nitrate were studied in two-kidney, one-clip (2K1C) hypertensive rats treated with omeprazole (or vehicle). Oral nitrite lowered blood pressure and increased plasma S-nitrosothiol concentrations independently of circulating nitrite levels. Increasing gastric pH with omeprazole did not affect the increases in plasma nitrite and nitrate levels found after treatment with nitrite. However, treatment with omeprazole severely attenuated the increases in plasma S-nitrosothiol concentrations and completely blunted the antihypertensive effects of nitrite. Confirming these findings, very similar results were found with oral nitrate. To further confirm the role of gastric S-nitrosothiol formation, we studied the effects of oral nitrite in hypertensive rats treated with the glutathione synthase inhibitor buthionine sulfoximine (BSO) to induce partial thiol depletion. BSO treatment attenuated the increases in S-nitrosothiol concentrations and antihypertensive effects of oral nitrite. These data show that gastric S-nitrosothiol formation drives the antihypertensive effects of oral nitrite or nitrate and has major implications, particularly to patients taking proton pump inhibitors. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Analysis of the monitoring status of residual nitrite in meat products in China from 2000 to 2011.

    Science.gov (United States)

    Zhang, Hongchao; Sun, Changbao; Han, Wanjun; Zhang, Jiaxiu; Hou, Juncai

    2018-02-01

    The aim of this article was to analyze the monitoring status of nitrite in meat products consumed from 2000 to 2011 in 24 provinces, autonomous regions or direct-controlled municipalities in China. Statistical analyses were performed on the monitoring status including number, proportion, and distribution of 13,316 samples, of which 11,320 (85%) contained up to 2808.2mg/kg nitrite and 1996 (15%) contained no nitrite. A total of 10,299 samples (77%) qualified for GB/T 5009.33-2003, 2003; however, 3017 samples (23%) contained nitrite at levels higher than the national standard. The districts with high percentage of samples with no nitrite were Shanghai (49%), Beijing (47%), and Liaoning (30%). While the districts with high percentage of meat products containing nitrite at levels exceeding the national standard were Jiangxi (49%), Jiangsu (33%), Shandong (29%) and Sichuan (29%). Therefore, the status of residue nitrite in meat products is of concern. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. An investigation into the unusual linkage isomerization and nitrite reduction activity of a novel tris(2-pyridyl) copper complex

    Science.gov (United States)

    Roger, Isolda; Wilson, Claire; Senn, Hans M.; Sproules, Stephen; Symes, Mark D.

    2017-08-01

    The copper-containing nitrite reductases (CuNIRs) are a class of enzymes that mediate the reduction of nitrite to nitric oxide in biological systems. Metal-ligand complexes that reproduce the salient features of the active site of CuNIRs are therefore of fundamental interest, both for elucidating the possible mode of action of the enzymes and for developing biomimetic catalysts for nitrite reduction. Herein, we describe the synthesis and characterization of a new tris(2-pyridyl) copper complex ([Cu1(NO2)2]) that binds two molecules of nitrite, and displays all three of the common binding modes for NO2-, with one nitrite bound in an asymmetric quasi-bidentate κ2-ONO manner and the other bound in a monodentate fashion with a linkage isomerism between the κ1-ONO and κ1-NO2 binding modes. We use density functional theory to help rationalize the presence of all three of these linkage isomers in one compound, before assessing the redox activity of [Cu1(NO2)2]. These latter studies show that the complex is not a competent nitrite reduction electrocatalyst in non-aqueous solvent, even in the presence of additional proton donors, a finding which may have implications for the design of biomimetic catalysts for nitrite reduction.

  14. Acute Toxicity of Nitrite to Various Life Stages of the Amazon River Prawn, Macrobrachium amazonicum, Heller, 1862.

    Science.gov (United States)

    Dutra, Fabrício Martins; Freire, Carolina Arruda; Vaz Dos Santos, André Martins; Forneck, Sandra Carla; Brazão, Claudia Caramelo; Ballester, Eduardo Luis Cupertino

    2016-11-01

    This study determined the effects of nitrite on different life stages of the Amazon river prawn Macrobrachium amazonicum. Prawns of each life stage (postlarvae, juveniles and adults) were stocked in 24 experimental units (n = 10 prawns), under a complete randomized design. Individuals were exposed to nitrite (0, 1, 2, 4, 8 and 16 mg L-1). The median lethal concentration after 96 h (96 h LC50) was calculated through the Weibull I. The mortality results showed that M. amazonicum is slightly less tolerant to nitrite than other species of Macrobrachium. The 96 h LC50 for postlarvae, juveniles and adults of M. amazonicum were of 1.49, 2.36 and 2.34 mg nitrite/L, respectively. Nitrite intoxication risk quotient suggest moderated risk to low risk to the species. Usually in production systems nitrite values are lower than safe levels suggested in this study (0.1 mg L-1 to postlarvae and 0.2 mg L-1 nitrite to juvenile and adults), which makes our results appropriate for the production of this species.

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

    DEFF Research Database (Denmark)

    Lefevre, Sjannie; Jensen, Frank Bo; 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......% of total Hb. Haematocrit and total Hb were unaffected by nitrite. Although the effects of nitrite exposure seemed minor in terms of plasma nitrite and metHb increases, ion balance was strongly affected. In the high exposure group, total osmolality decreased from 320 mOsm to 260 mOsm, and plasma sodium from...

  16. The increase in plasma nitrite after a dietary nitrate load is markedly attenuated by an antibacterial mouthwash.

    Science.gov (United States)

    Govoni, Mirco; Jansson, Emmelie A; Weitzberg, Eddie; Lundberg, Jon O

    2008-12-01

    Recent studies surprisingly show that dietary inorganic nitrate, abundant in vegetables, can be metabolized in vivo to form nitrite and then bioactive nitric oxide. A reduction in blood pressure was recently noted in healthy volunteers after dietary supplementation with nitrate; an effect consistent with formation of vasodilatory nitric oxide. Oral bacteria have been suggested to play a role in bioactivation of nitrate by first reducing it to the more reactive anion nitrite. In a cross-over designed study in seven healthy volunteers we examined the effects of a commercially available chlorhexidine-containing antibacterial mouthwash on salivary and plasma levels of nitrite measured after an oral intake of sodium nitrate (10mg/kg dissolved in water). In the control situation the salivary and plasma levels of nitrate and nitrite increased greatly after the nitrate load. Rinsing the mouth with the antibacterial mouthwash prior to the nitrate load had no effect on nitrate accumulation in saliva or plasma but abolished its conversion to nitrite in saliva and markedly attenuated the rise in plasma nitrite. We conclude that the acute increase in plasma nitrite seen after a nitrate load is critically dependent on nitrate reduction in the oral cavity by commensal bacteria. The removal of these bacteria with an antibacterial mouthwash will very likely attenuate the NO-dependent biological effects of dietary nitrate.

  17. Effect of electrolyzed oxidizing water treatment on the reduction of nitrite levels in fresh spinach during storage.

    Science.gov (United States)

    Hao, Jianxiong; Li, Huiying; Wan, Yangfang; Liu, Haijie

    2015-03-01

    Leafy vegetables are the major source of nitrite intake in the human diet, and technological processing to control nitrite levels in harvested vegetables is necessary. In the current work, the effect of electrolyzed oxidizing water (EOW) on the nitrite and nitrate levels in fresh spinach during storage was studied. EOW treatment, including slightly acidic electrolyzed water and acidic electrolyzed water, was found to effectively reduce nitrite levels in fresh spinach during storage; levels in the late period were 30 to 40% lower than that of the control. However, the nitrate levels in fresh spinach during storage were not influenced by EOW treatment. The reduction of nitrite levels in EOW-treated fresh spinach during storage can be attributed to the inactivation of nitrate reductase directly and to the reduction of bacterial populations. Our results suggest that treatment with slightly acidic electrolyzed water may be a better choice to control nitrite levels in fresh vegetables during storage. This study provided a useful method to reduce nitrite levels in fresh spinach.

  18. Impact of nitrite on detection of Listeria monocytogenes in selected ready-to-eat (RTE) meat and seafood products.

    Science.gov (United States)

    Nyachuba, D G; Donnelly, C W; Howard, A B

    2007-09-01

    The impact of sodium nitrite (NaNO2) on detection and recovery of Listeria monocytogenes from select ready-to-eat (RTE) foods including smoked salmon, smoked ham, beef frankfurters, and beef bologna was assessed. Nitrite-containing (NC; 100 to 200 ppm NaNO2) or nitrite-free (NF) foods were inoculated with a 5-strain cocktail of L. monocytogenes by immersion into Butterfield's buffer solution containing 5.4 to 7.4 x 10(3) L. monocytogenes per milliliter. Inoculated products were vacuum-packaged and stored at 5 degrees C. A weekly comparative analysis was performed for presence of L. monocytogenes using 5 detection methods on products held at 5 degrees C for up to 8 wk. L. monocytogenes initially present at Listeria-positive food samples and were consistently superior to and significantly different (P Listeria from NC samples. Data show that nitrite-induced injury adversely affects detection and recovery of L. monocytogenes from NC food, confirming earlier findings that nitrite-induced injury masks L. monocytogenes detection in NC RTE food products. Nitrite-injured Listeria can subsequently repair upon nitrite depletion and grow to high levels over extended refrigerated storage.

  19. Crystal structures of manganese- and cobalt-substituted myoglobin in complex with NO and nitrite reveal unusual ligand conformations.

    Science.gov (United States)

    Zahran, Zaki N; Chooback, Lilian; Copeland, Daniel M; West, Ann H; Richter-Addo, George B

    2008-02-01

    Nitrite is now recognized as a storage pool of bioactive nitric oxide (NO). Hemoglobin (Hb) and myoglobin (Mb) convert, under certain conditions, nitrite to NO. This newly discovered nitrite reductase activity of Hb and Mb provides an attractive alternative to mammalian NO synthesis from the NO synthase pathway that requires dioxygen. We recently reported the X-ray crystal structure of the nitrite adduct of ferric horse heart Mb, and showed that the nitrite ligand binds in an unprecedented O-binding (nitrito) mode to the d(5) ferric center in Mb(III)(ONO) [D.M. Copeland, A. Soares, A.H. West, G.B. Richter-Addo, J. Inorg. Biochem. 100 (2006) 1413-1425]. We also showed that the distal pocket in Mb allows for different conformations of the NO ligand (120 degrees and 144 degrees ) in Mb(II)NO depending on the mode of preparation of the compound. In this article, we report the crystal structures of the nitrite and NO adducts of manganese-substituted hh Mb (a d(4) system) and of the nitrite adduct of cobalt-substituted hh Mb (a d(6) system). We show that the distal His64 residue directs the nitrite ligand towards the rare nitrito O-binding mode in Mn(III)Mb and Co(III)Mb. We also report that the distal pocket residues allow a stabilization of an unprecendented bent MnNO moiety in Mn(II)MbNO. These crystal structural data, when combined with the data for the aquo, methanol, and azide MnMb derivatives, provide information on the role of distal pocket residues in the observed binding modes of nitrite and NO ligands to wild-type and metal-substituted Mb.

  20. Interspecific variation and plasticity in hemoglobin nitrite reductase activity and its correlation with oxygen affinity in vertebrates.

    Science.gov (United States)

    Jensen, Frank B; Kolind, Rasmus A H; Jensen, Natashia S; Montesanti, Gabriella; Wang, Tobias

    2017-04-01

    Deoxygenated hemoglobin (Hb) is a nitrite reductase that reduces naturally occurring nitrite to nitric oxide (NO), supplying physiological relevant NO under hypoxic conditions. The nitrite reductase activity is modulated by the allosteric equilibrium between the R and T structures of Hb that also 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, Indian python and red-eared slider turtle), while it was sigmoid in mammals (harbor porpoise and rabbit). Typically, hypoxia-tolerant species showed a faster reaction than intolerant species. Addition of ATP and GTP decreased O2 affinity and slowed the rate of nitrite reduction in a concentration-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 predicts high nitrite reductase activity in hypoxic tolerant species with high Hb-O2 affinity and reveals that the decrease in erythrocyte ATP and/or GTP during acclimation to hypoxia in ectotherms increases the erythrocyte NO generating capacity. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Sustained release nitrite therapy results in myocardial protection in a porcine model of metabolic syndrome with peripheral vascular disease.

    Science.gov (United States)

    Bradley, Jessica M; Islam, Kazi N; Polhemus, David J; Donnarumma, Erminia; Brewster, Luke P; Tao, Ya-Xiong; Goodchild, Traci T; Lefer, David J

    2015-07-15

    Metabolic syndrome (MetS) reduces endothelial nitric oxide (NO) bioavailability and exacerbates vascular dysfunction in patients with preexisting vascular diseases. Nitrite, a storage form of NO, can mediate vascular function during pathological conditions when endogenous NO is reduced. The aims of the present study were to characterize the effects of severe MetS and obesity on dyslipidemia, myocardial oxidative stress, and endothelial NO synthase (eNOS) regulation in the obese Ossabaw swine (OS) model and to examine the effects of a novel, sustained-release formulation of sodium nitrite (SR-nitrite) on coronary vascular reactivity and myocardial redox status in obese OS subjected to critical limb ischemia (CLI). After 6 mo of an atherogenic diet, obese OS displayed a MetS phenotype. Obese OS had decreased eNOS functionality and NO bioavailability. In addition, obese OS exhibited increased oxidative stress and a significant reduction in antioxidant enzymes. The efficacy of SR-nitrite therapy was examined in obese OS subjected to CLI. After 3 wk of treatment, SR-nitrite (80 mg · kg(-1) · day(-1) bid po) increased myocardial nitrite levels and eNOS function. Treatment with SR-nitrite reduced myocardial oxidative stress while increasing myocardial antioxidant capacity. Ex vivo assessment of vascular reactivity of left anterior descending coronary artery segments demonstrated marked improvement in vasoreactivity to sodium nitroprusside but not to substance P and bradykinin in SR-nitrite-treated animals compared with placebo-treated animals. In conclusion, in a clinically relevant, large-animal model of MetS and CLI, treatment with SR-nitrite enhanced myocardial NO bioavailability, attenuated oxidative stress, and improved ex vivo coronary artery vasorelaxation.

  2. Expression of a putative nitrite reductase and the reversible inhibition of nitrite-dependent respiration by nitric oxide in Nitrobacter winogradskyi Nb-255.

    Science.gov (United States)

    Starkenburg, Shawn R; Arp, Daniel J; Bottomley, Peter J

    2008-11-01

    The nitrite oxidizing Alphaproteobacterium, Nitrobacter winogradskyi, primarily conserves energy from the oxidation of nitrite (NO(2)(-))to nitrate (NO(3)(-)) through aerobic respiration. Almost 20 years ago, NO-dependent NADH formation was reported to occur in both aerobic and anaerobic cell suspensions of N. winogradskyi strain 'agilis', suggesting that NO oxidation might contribute to energy conservation by Nitrobacter. Recently, the N. winogradskyi Nb-255 genome was found to contain a gene (Nwin_2648) that encodes a putative copper-containing nitrite reductase (NirK), which may reduce NO(2)(-) to NO. In this study, the putative nirK was found to be maximally transcribed under low O(2) (between zero and 4% O(2)) in the presence of NO(2)(-). Transcription of nirK was not detected under anaerobic conditions in the absence of NO(2)(-) or in the presence of NO(3)(-) and pyruvate. Although net production of NO could not be detected from either aerobically grown or anaerobically incubated cells, exogenous NO was consumed by viable cells and concomitantly inhibited NO(2)(-)-dependent O(2) uptake in a reversible, concentration dependent manner. Both NO(2(-)-dependent O(2) uptake and NO consumption were inhibited by 1 mM cyanide suggesting involvement of cytochrome oxidase with NO consumption. Abiotic consumption of NO was measured, yet, both the rates and kinetics of NO transformation in buffer alone, or by heat killed, or cyanide-treated cells differed from those of viable cells. In light of this new information, a modified model is proposed to explain how NirK and NO manage electron flux in Nitrobacter.

  3. Calcium signaling in taste cells.

    Science.gov (United States)

    Medler, Kathryn F

    2015-09-01

    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. This article is part of a Special Issue entitled: 13th European Symposium on Calcium. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. 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

    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......-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...

  5. Urinary Excretion of N-Nitroso Compounds in Rats Fed Sodium Nitrite and/or Hot Dogs

    OpenAIRE

    Zhou, Lin; Anwar, Muhammad M.; Zahid, Muhammad; Shostrom, Valerie; Mirvish, Sidney S

    2014-01-01

    Nitrite-treated meat is a reported risk factor for colon cancer. Mice that ingested sodium nitrite (NaNO2) or hot dogs (a nitrite-treated product) showed increased fecal excretion of apparent N-nitroso compounds (ANC). Here, we investigated for the first time whether rats excrete increased amounts of ANC in their urine after they are fed NaNO2 and/or hot dogs. Rats were treated for 7 days with NaNO2 in drinking water or were fed hot dogs. Their 24 h urine samples were analyzed for ANC by ther...

  6. 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.

  7. Effect of betaine supplementation on plasma nitrate/nitrite in exercise-trained men

    Directory of Open Access Journals (Sweden)

    McCarthy Cameron G

    2011-03-01

    Full Text Available Abstract Background Betaine, beetroot juice, and supplemental nitrate have recently been reported to improve certain aspects of exercise performance, which may be mechanistically linked to increased nitric oxide. The purpose of the present study was to investigate the effect of betaine supplementation on plasma nitrate/nitrite, a surrogate marker or nitric oxide, in exercise-trained men. Methods We used three different study designs (acute intake of betaine at 1.25 and 5.00 grams, chronic intake of betaine at 2.5 grams per day for 14 days, and chronic [6 grams of betaine per day for 7 days] followed by acute intake [6 grams], all involving exercise-trained men, to investigate the effects of orally ingested betaine on plasma nitrate/nitrite. Blood samples were collected before and at 30, 60, 90, and 120 min after ingestion of 1.25 and 5.00 grams of betaine (Study 1; before and after 14 days of betaine supplementation at a dosage of 2.5 grams (Study 2; and before and after 7 days of betaine supplementation at a dosage of 6 grams, followed by acute ingestion of 6 grams and blood measures at 30 and 60 min post ingestion (Study 3. Results In Study 1, nitrate/nitrite was relatively unaffected and no statistically significant interaction (p = 0.99, dosage (p = 0.69, or time (p = 0.91 effects were noted. Similar findings were noted in Study 2, with no statistically significant interaction (p = 0.57, condition (p = 0.98, or pre/post intervention (p = 0.17 effects noted for nitrate/nitrite. In Study 3, no statistically significant changes were noted in nitrate/nitrite between collection times (p = 0.97. Conclusion Our data indicate that acute or chronic ingestion of betaine by healthy, exercise-trained men does not impact plasma nitrate/nitrite. These findings suggest that other mechanisms aside from increasing circulating nitric oxide are likely responsible for any performance enhancing effect of betaine supplementation.

  8. Suggestive evidence for the induction of colonic aberrant crypts in mice fed sodium nitrite.

    Science.gov (United States)

    Zhou, Lin; Zahid, Muhammad; Anwar, Muhammad M; Pennington, Karen L; Cohen, Samuel M; Wisecarver, James L; Shostrom, Valerie; Mirvish, Sidney S

    2016-01-01

    A reported linkage between processed (nitrite-treated) meat products and the incidence of colon cancer could be due to sodium nitrite (NaNO2) itself or to N-nitroso compounds produced from the nitrite. Exposure to nitrite occurs due to residual nitrite in processed meat and to salivary nitrite arising by reduction of nitrate in vegetables and drinking water. Here we tested whether NaNO2 could induce colonic aberrant crypts (ABC) or ABC foci (ACF), which are putative precursors of colon cancer. We fed NaNO2 in drinking water for 20-25 wk to groups of 8-20 adult female mice. After sacrifice, ABC and ACF were counted in 2-cm distal colonic segments. In Experiment 1, no significant differences in ABC/ACF induction were seen between groups of 13-14 A/J mice fed 0, 0.5, or 1.0 g NaNO2/l drinking water. NaNO2 also did not affect fasting blood glucose levels. In Experiment 2, we fed 0, 1.0, 1.25, or 1.5 g NaNO2/l water to groups of 15 CF-1 mice. Five of the mice fed 1.5 g NaNO2/l showed ABC, whereas all other groups showed only 0-2 ABC/group, including 0 ABC for the group fed 1.25 g NaNO2/l. Overall statistical analysis indicated a dose-response p trends of 0.04. Pairwise comparison of ABC between groups fed 1.25 and 1.5 g NaNO2/l showed p 0.02 for both ABC and ACF, but a similar comparison between the untreated and 1.5 g/l groups showed no significant effects. In Experiment 3, hot dogs (18% of diet), which were fed to CF-1 mice previously treated with azoxymethane, inhibited ABC and ACF induction, but this effect was not significant (P = 0.10-0.12). In conclusion, these results support the view that NaNO2 may be a risk factor for colon carcinogenesis.

  9. DISTILLATION OF CALCIUM

    Science.gov (United States)

    Barton, J.

    1954-07-27

    This invention relates to an improvement in the process for the purification of caicium or magnesium containing an alkali metal as impurity, which comprises distiiling a batch of the mixture in two stages, the first stage distillation being carried out in the presence of an inert gas at an absolute pressure substantially greater than the vapor pressure of calcium or maguesium at the temperature of distillation, but less than the vaper pressure at that temperature of the alkali metal impurity so that only the alkali metal is vaporized and condensed on a condensing surface. A second stage distilso that substantially only the calcium or magnesium distills under its own vapor pressure only and condenses in solid form on a lower condensing surface.

  10. Calcium metabolism and cardiovascular function after spaceflight

    Science.gov (United States)

    Hatton, Daniel C.; Yue, Qi; Dierickx, Jacqueline; Roullet, Chantal; Otsuka, Keiichi; Watanabe, Mitsuaki; Coste, Sarah; Roullet, Jean Baptiste; Phanouvang, Thongchan; Orwoll, Eric; hide

    2002-01-01

    To determine the influence of dietary calcium on spaceflight-induced alterations in calcium metabolism and blood pressure (BP), 9-wk-old spontaneously hypertensive rats, fed either high- (2%) or low-calcium (0.02%) diets, were flown on an 18-day shuttle flight. On landing, flight animals had increased ionized calcium (P platelet free calcium (intracellular calcium concentration) were also reduced (P metabolism (P metabolism are relatively impervious to dietary calcium in the short term, 2) increased ionized calcium did not normalize low-calcium-induced elevations of BP, and 3) parathyroid hormone was paradoxically increased in the high-calcium-fed flight animals after landing.

  11. 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...

  12. 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

    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...... 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...

  13. Elemental calcium intake associated with calcium acetate/calcium carbonate in the treatment of hyperphosphatemia.

    Science.gov (United States)

    Wilson, Rosamund J; Copley, J Brian

    2017-01-01

    Calcium-based and non-calcium-based phosphate binders have similar efficacy in the treatment of hyperphosphatemia; however, calcium-based binders may be associated with hypercalcemia, vascular calcification, and adynamic bone disease. A post hoc analysis was carried out of data from a 16-week, Phase IV study of patients with end-stage renal disease (ESRD) who switched to lanthanum carbonate monotherapy from baseline calcium acetate/calcium carbonate monotherapy. Of the intent-to-treat population (N=2520), 752 patients with recorded dose data for calcium acetate (n=551)/calcium carbonate (n=201) at baseline and lanthanum carbonate at week 16 were studied. Elemental calcium intake, serum phosphate, corrected serum calcium, and serum intact parathyroid hormone levels were analyzed. Of the 551 patients with calcium acetate dose data, 271 (49.2%) had an elemental calcium intake of at least 1.5 g/day at baseline, and 142 (25.8%) had an intake of at least 2.0 g/day. Mean (95% confidence interval [CI]) serum phosphate levels were 6.1 (5.89, 6.21) mg/dL at baseline and 6.2 (6.04, 6.38) mg/dL at 16 weeks; mean (95% CI) corrected serum calcium levels were 9.3 (9.16, 9.44) mg/dL and 9.2 (9.06, 9.34) mg/dL, respectively. Of the 201 patients with calcium carbonate dose data, 117 (58.2%) had an elemental calcium intake of at least 1.5 g/day, and 76 (37.8%) had an intake of at least 2.0 g/day. Mean (95% CI) serum phosphate levels were 5.8 (5.52, 6.06) mg/dL at baseline and 5.8 (5.53, 6.05) mg/dL at week 16; mean (95% CI) corrected serum calcium levels were 9.7 (9.15, 10.25) mg/dL and 9.2 (9.06, 9.34) mg/dL, respectively. Calcium acetate/calcium carbonate phosphate binders, taken to control serum phosphate levels, may result in high levels of elemental calcium intake. This may lead to complications related to calcium balance.

  14. Nitrate-nitrite toxicity in cattle and sheep grazing Dactyloctenium radulans (button grass) in stockyards.

    Science.gov (United States)

    McKenzie, R A; Rayner, A C; Thompson, G K; Pidgeon, G F; Burren, B R

    2004-10-01

    Hungry cattle and sheep introduced to stockyards containing a dominant or pure growth of Dactyloctenium radulans (button grass) suffered acute nitrate-nitrite toxicity in four incidents in inland Queensland between 1993 and 2001. Deaths ranged from 16 to 44%. Methaemoglobinaemia was noted at necropsies in all incidents. An aqueous humour sample from one dead steer contained 75 mg nitrate/L and from one dead sheep contained 100 mg nitrate and 50 mg nitrite/L (normal = ca 5 mg nitrate/L). Both lush and dry button grass were toxic. The nitrate content of button grass from within the stockyards ranged from 4.0 to 12.9% as potassium nitrate equivalent in dry matter and from outside the stockyards ranged from stockyard soil may boost the nitrate content of button grass to a concentration hazardous to hungry ruminants.

  15. Therapeutic Potential of the Nitrite-Generated NO Pathway in Vascular Dysfunction

    Science.gov (United States)

    Madigan, Michael; Zuckerbraun, Brian

    2013-01-01

    Nitric oxide (NO) generated through L-arginine metabolism by endothelial nitric oxide synthase (eNOS) is an important regulator of the vessel wall. Dysregulation of this system has been implicated in various pathological vascular conditions, including atherosclerosis, angiogenesis, arteriogenesis, neointimal hyperplasia, and pulmonary hypertension. The pathophysiology involves a decreased bioavailability of NO within the vessel wall by competitive utilization of L-arginine by arginase and “eNOS uncoupling.” Generation of NO through reduction of nitrate and nitrite represents an alternative pathway that may be utilized to increase the bioavailability of NO within the vessel wall. We review the therapeutic potential of the nitrate/nitrite/NO pathway in vascular dysfunction. PMID:23847616

  16. Shortcut nitrification/partial nitritation start-up for reject water treatment in a SBR

    Science.gov (United States)

    Muszyński-Huhajło, Mateusz; Miodoński, Stanisław

    2017-11-01

    For many wastewater treatment plants (WWTPs), side-stream treatment of reject water from digested sludge dewatering is a feasible opportunity to improve N-removal efficiency without costly plant expansion. Biological nitrogen removal over nitrite or combined partial nitritation (PN)-Anammox process has recently become a popular treatment method for such ammonium-rich streams. Shortcut nitrification and PN start-ups were successfully performed in a pilot-scale SBR treating real reject water. In all performed experiments, effective nitrate production inhibition occurred in less than 20 days due to operational conditions selection and without advanced control system. pH adjustment in the PN reactor allowed to achieve NO2-N /NH4-N ratio suitable for Anammox process (1.24±0.07).

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

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    for nitrogen removal from surface waters. In this study, a sediment-type MFC based on two pieces of bioelectrodes was employed as a novel in situ applicable approach for nitrogen removal, as well as electricity production from eutrophic lakes. Maximum power density of 42 and 36 mW/m2 were produced respectively...... 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...... oxygen (DO) level in the water and acetate level injected to the sediment. Excessive oxygen resulted in dramatically decrease of nitrogen removal efficiency and only 7.8% removal was obtained at DO level of 7.8 mg/l. The power generation and nitrogen removal increased with acetate level and was nearly...

  18. 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

    for nitrogen removal from surface waters. In this study, a sediment-type MFC based on two pieces of bioelectrodes was employed as a novel in situ applicable approach for nitrogen removal, as well as electricity production from eutrophic lakes. Maximum power density of 42 and 36 mW/m2 were produced respectively...... 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...... oxygen (DO) level in the water and acetate level injected to the sediment. Excessive oxygen resulted in dramatically decrease of nitrogen removal efficiency and only 7.8% removal was obtained at DO level of 7.8 mg/l. The power generation and nitrogen removal increased with acetate level and was nearly...

  19. The determination of nitrite by a graphene quantum dot fluorescence quenching method without sample pretreatment.

    Science.gov (United States)

    Jin, Li; Wang, Ying; Liu, Fangtong; Yu, Shihua; Gao, Yan; Zhang, Jianpo

    2017-10-25

    A method for quantitative analysis of nitrite was achieved based on fluorescence quenching of graphene quantum dots. To obtain reliable results, the effects of pH, temperature and reaction time on this fluorescence quenching system were studied. Under optimized conditions, decrease in fluorescence intensity of graphene quantum dots (F0 /F) showed a good linear relationship with nitrite concentration between 0.007692-0.38406 mmol/L and 0.03623-0.13043 μmol/L; the limits of detection were 9.8 μmol/L and 5.4 nmol/L, respectively. Variable temperature experiments, UV absorption spectra and thermodynamic calculations were used to determine the quenching mechanism, and indicated that it was an exothermic, spontaneous dynamic quenching process. This method was used to analyse urine samples, and showed that it could be applied to analyse biological samples. Copyright © 2017 John Wiley & Sons, Ltd.

  20. Optical nitrite sensor based on chemical modification of a polymer film

    Science.gov (United States)

    Kazemzadeh, A.; Daghighi, S.

    2005-06-01

    A new, low-cost nitrite sensor was developed by immobilizing a direct indicator dye in an optical sensing film for food and environmental monitoring. This sensor was fabricated by binding gallocyanine to a cellulose acetate film that had previously been subjected to an exhaustive base hydrolysis. The membrane has good durability (>6 months) and a short response time (<7 s). Nitrite can be determined for the range 0.008-1.50 μg/ml with 3 δ detection limits of 1 ng/ml. The method is easy to perform and uses acetylcellulose as a carrier. The reagents used for activating the cellulose support are inexpensive, non-toxic and widely available.

  1. 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.

  2. [Nitrate and nitrite contents in vegetable juice, tea beverage and mineral water on the market].

    Science.gov (United States)

    Murata, Mihoko; Ishinaga, Masataka

    2005-08-01

    The contents of nitrate and nitrite in vegetable juice (n = 63), tea beverage (n = 12) and mineral water (n = 15) were measured. The mean contents of nitrate were 0.73 +/- 14.57 mg/100 g, 0.61 +/- 1.12 mg/100 g and 0.25 +/- 0.33 mg/100 g as NO3-, respectively. The contents of the nitrite were 0.03 +/- 0.05 mg/100 g, 0.02 +/- 0.01 mg/100 g and 0.001 +/- 0.001 mg/100 g as NO2-, respectively. The content of nitrate is high in some vegetable juices, and warnings may be necessary for people who drink them frequently.

  3. 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...

  4. Effect of Fermented Spinach as Sources of Pre-Converted Nitrite on Color Development of Cured Pork Loin

    OpenAIRE

    Kim, Tae-Kyung; Kim, Young-Boong; Jeon, Ki-Hong; Park, Jong-Dae; Sung, Jung-Min; Choi, Hyun-Wook; Hwang, Ko-Eun; Choi, Yun-Sang

    2017-01-01

    The effect of fermented spinach extracts on color development in cured meats was investigated in this study. The pH values of raw cured meats without addition of fermented spinach extract or nitrite (negative control) were higher (p

  5. Utilization of urea, ammonia, nitrite, and nitrate by crop plants in a Controlled Ecological Life Support System (CELSS)

    Science.gov (United States)

    Huffaker, R. C.; Rains, D. W.; Qualset, C. O.

    1982-01-01

    The utilization of nitrogen compounds by crop plants is studied. The selection of crop varieties for efficient production using urea, ammonia, nitrite, and nitrate, and the assimilation of mixed nitrogen sources by cereal leaves and roots are discussed.

  6. 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

    2017-04-15

    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 1.2μM. 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. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. 78 FR 68474 - Sodium Nitrite From China And Germany; Scheduling of Expedited Five-Year Reviews Concerning the...

    Science.gov (United States)

    2013-11-14

    ... duty order on sodium nitrite from Germany would be likely to lead to continuation or recurrence of...'s TDD terminal on 202-205-1810. Persons with mobility impairments who will need special assistance...

  8. 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...... in the reaction induces vasodilation in aortic rings. This reaction occurs under normoxic and hypoxic conditions and in various tissues at physiological levels of CA and nitrite. Furthermore, two specific inhibitors of the CO2 hydration, dorzolamide and acetazolamide, increase the CA-catalyzed production...... of vasoactive NO from nitrite. This enhancing effect may explain the known vasodilating effects of these drugs and indicates that CO2 and nitrite bind differently to the enzyme active site. Kinetic analyses show a higher reaction rate at high pH, suggesting that anionic nitrite participates more effectively...

  9. 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...

  10. Limestone reaction in calcium aluminate cement–calcium sulfate systems

    OpenAIRE

    Bizzozero, Julien; Scrivener, Karen

    2015-01-01

    This paper reports a study of ternary blends composed of calcium aluminate cement, calcium sulfate hemihydrate and limestone. Compressive strength tests and hydration kinetics were studied as a function of limestone and calcium sulfate content. The phase evolution and the total porosity were followed and compared to thermodynamic simulation to understand the reactions involved and the effect of limestone on these binders. The reaction of limestone leads to the formation of hemicarboaluminate ...

  11. Mixed calcium-magnesium pre-nucleation clusters enrich calcium

    OpenAIRE

    Verch, Andreas; Antonietti, Markus; Cölfen, Helmut

    2012-01-01

    It is demonstrated that magnesium and carbonate ions can form pre-nucleation clusters in analogy to calcium carbonate. If a mixed calcium and magnesium solution is brought in contact with carbonate ions, mixed pre-nucleation clusters form. The equilibrium constants for their formation are reported revealing that over the entire range of possible cation mixing ratios, calcium gets enriched over magnesium in the pre-nucleation clusters. This can explain high magnesium contents in amorphous calc...

  12. Facile synthesis of flower like copper oxide and their application to hydrogen peroxide and nitrite sensing

    OpenAIRE

    Zhang Li; Yuan Feifei; Zhang Xiaohu; Yang Liming

    2011-01-01

    Abstract Background The detection of hydrogen peroxide (H2O2) and nitrite ion (NO2-) is of great important in various fields including clinic, food, pharmaceutical and environmental analyses. Compared with many methods that have been developed for the determination of them, the electrochemical detection method has attracted much attention. In recent years, with the development of nanotechnology, many kinds of micro/nano-scale materials have been used in the construction of electrochemical bio...

  13. Short-and long-term effects of ammonia and nitrite on the anammox process

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, I.; Campos, J. L.; Mosquera-Corral, A.; Mendez, R.

    2009-07-01

    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)

  14. 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 % in the analytes. The electrode’s limit of detection and catalytic rate constant were 6.26 µM (4.37 x 106 cm3 mol-1 s-1) and 4.9 µM (6.35 x 105 cm3mol-1s-1) for nitrite and nitric oxide respectively. The fabricated electrode is not difficult to prepare and could...

  15. 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.

  16. Microbial resource management of one‐stage partial nitritation/anammox

    OpenAIRE

    Vlaeminck, S. E.; De Clippeleir, H.; Verstraete, W.

    2012-01-01

    Summary About 30 full‐scale partial nitritation/anammox plants are established, treating mostly sewage sludge reject water, landfill leachate or food processing digestate. Although two‐stage and one‐stage processes each have their advantages, the one‐stage configuration is mostly applied, termed here as oxygen‐limited autotrophic nitrification/denitrification (OLAND), and is the focus of this review. The OLAND application domain is gradually expanding, with technical‐scale plants on source‐se...

  17. Genome Sequence of the Chemolithoautotrophic Nitrite-Oxidizing Bacterium Nitrobacter winogradskyi Nb-255

    OpenAIRE

    Starkenburg, Shawn R.; Chain, Patrick S. G.; Sayavedra-Soto, Luis A.; Hauser, Loren; Land, Miriam L.; Larimer, Frank W.; Stephanie A Malfatti; Klotz, Martin G.; Bottomley, Peter J.; Arp, Daniel J.; Hickey, William J.

    2006-01-01

    The alphaproteobacterium Nitrobacter winogradskyi (ATCC 25391) is a gram-negative facultative chemolithoautotroph capable of extracting energy from the oxidation of nitrite to nitrate. Sequencing and analysis of its genome revealed a single circular chromosome of 3,402,093 bp encoding 3,143 predicted proteins. There were extensive similarities to genes in two alphaproteobacteria, Bradyrhizobium japonicum USDA110 (1,300 genes) and Rhodopseudomonas palustris CGA009 CG (815 genes). Genes encodin...

  18. 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.

  19. Combined exposure to ambient UVB radiation and nitrite negatively affects survival of amphibian early life stages

    OpenAIRE

    Macías, 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 g...

  20. 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.

  1. Voltammetric determination of nitrite in meat products using polyvinylimidazole modified carbon paste electrode.

    Science.gov (United States)

    Yildiz, Gulcemal; Oztekin, Nevin; Orbay, Ayca; Senkal, Filiz

    2014-01-01

    A simple and sensitive voltammetric method was developed to determine the amount of nitrite by using Carbon Paste Electrode (CPE) which is modified with polyvinylimidazole (PVI). A buffer solution of phosphate with a pH 4 value was used in the experiments. The amount of the nitrite-ion was determined by cyclic voltammetry (CV). The electro-chemical behaviour of nitrite-ion was investigated by using CV on the PVI modified CPE. A well-defined oxidation peak was obtained at 0.83 V against a reference Ag/AgCl electrode. Differential pulse voltammetry (DPV) was applied for the calibration plot and for the detection limit. The optimisation procedure was done in two steps: using a two-level factorial design for preliminary evaluation of the contributing factors, and the Box-Behnken Design (BBD) to assess the optimal experimental conditions. These are done with the analysis of 3 different factors in 15 runs of DPV. The optimum conditions are obtained within a linear response range of 5×10(-7)-1×10(-4) mol L(-1). Regression analysis is performed within this range showed the linear equation of y=0.028x+3.93×10(-7) with r(2)=0.9982, and for n=7. Limit of Detection (LOD) was 9×10(-8) mol L(-1) with S/N=3, and Limit of Quantification (LOQ) was 3×10(-7) mol L(-1) with S/N=10. The procedure was used successfully to detect the amount of nitrite in meat products. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Susceptibility of Clostridium difficile to the food preservatives sodium nitrite, sodium nitrate and sodium metabisulphite.

    Science.gov (United States)

    Lim, Su-Chen; Foster, Niki F; Riley, Thomas V

    2016-02-01

    Clostridium difficile is an important enteric pathogen of humans and food animals. Recently it has been isolated from retail foods with prevalences up to 42%, prompting concern that contaminated foods may be one of the reasons for increased community-acquired C. difficile infection (CA-CDI). A number of studies have examined the prevalence of C. difficile in raw meats and fresh vegetables; however, fewer studies have examined the prevalence of C. difficile in ready-to-eat meat. The aim of this study was to investigate the in vitro susceptibility of 11 C. difficile isolates of food animal and retail food origins to food preservatives commonly used in ready-to-eat meats. The broth microdilution method was used to determine the minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) for sodium nitrite, sodium nitrate and sodium metabisulphite against C. difficile. Checkerboard assays were used to investigate the combined effect of sodium nitrite and sodium nitrate, commonly used in combination in meats. Modal MIC values for sodium nitrite, sodium nitrate and sodium metabisulphite were 250 μg/ml, >4000 μg/ml and 1000 μg/ml, respectively. No bactericidal activity was observed for all three food preservatives. The checkerboard assays showed indifferent interaction between sodium nitrite and sodium nitrate. This study demonstrated that C. difficile can survive in the presence of food preservatives at concentrations higher than the current maximum permitted levels allowed in ready-to-eat meats. The possibility of retail ready-to-eat meats contaminated with C. difficile acting as a source of CDI needs to be investigated. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Effects of Lactic Acid Bacteria on Residual Nitrite in a Summer Style Sausage.

    Science.gov (United States)

    1984-01-01

    and odors resulting from rancidity. This condition is caused by the breakdown of unsaturated fats, and subsequent release of free fatty acids, by the...and Ziegler (1965) concluded that nitrite interferes with the oxidation of unsaturated lipids, possibly by complexing with heme-containing 0 catalysts...fat, 52.5% moisture, 18.0% protein, 1.0% ash. 0 repetitions. Two additional treatments were added for comparison; glucono delta lactone and

  4. Biological Reactions to Calcium Phosphate-coated Calcium Carbonate Particles

    National Research Council Canada - National Science Library

    Tetsunari NISHIKAWA; Kazuya MASUNO; Tomoharu OKAMURA; Kazuya TOMINAGA; Masahiro WATO; Mayu KOKUBU; Koichi IMAI; Shoji TAKEDA; Yoichro TAGUCHI; Masatoshi UEDA; Akio TANAKA

    2010-01-01

    [SYNOPSIS][Objectives]: In order to histopathologically investigate biological reactions to materials used for scaffolds, we examined the cytotoxicity to calcium particles in vitro and bioabsorption in vivo...

  5. Changes in hemolymph oxyhemocyanin, acid-base balance, and electrolytes in Marsupenaeus japonicus under combined ammonia and nitrite stress.

    Science.gov (United States)

    Cheng, Sha-Yen; Shieh, Li-Wei; Chen, Jiann-Chu

    2013-04-15

    Ammonia and nitrite are the most common toxic nitrogenous compounds in aquaculture ponds. We evaluated the effects of a combined treatment with these two compounds on the hemolymph acid-base balance, electrolytes and oxyhemocyanin content in kuruma shrimp, (Marsupenaeus japonicus). The shrimp (6.37±1.29 g) were individually exposed to 9 different ammonia and nitrite regimes {ammonia at 0 (control), 0.39, and 1.49 mM combined with nitrite at 0 (control), 0.38, and 1.49 mM} in a 30‰ saline solution at 22°C. Hemolymph oxyhemocyanin (OxyHc), protein content, acid-base balance, osmolality, and electrolyte levels were measured in treated shrimp after 48 h of treatment. Hemolymph OxyHc, protein content, the OxyHc/protein ratio, pH, pCO2, HCO3(-), TCO2, OH(-)/H(+), osmolality, and Cl(-), Na(+), K(+), Ca(2+), and Mg(2+) levels were inversely related to the dose of ammonia and nitrite. However, hemolymph pO2 levels directly increased with the ammonia and nitrite concentrations. Following exposure to 1.49 mM ammonia+1.49 mM nitrite, the hemolymph pO2 increased by 89.5%, whereas the hemolymph OxyHc, protein content, OxyHc/protein ratio, pH, pCO2, HCO3(-), TCO2, OH(-)/H(+), osmolality, Cl(-), and Na(+) decreased by 51.2, 28.2, 34.9, 2.9, 51.1, 71.5, 70.8, 42.8, 4.9, 32.1, and 38.6%, respectively, compared with control shrimp. Combined ammonia and nitrite stress may therefore exert a synergistic effect on shrimp relative to the stress induced by ammonia or nitrite alone. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Effects of organic tomato pulp powder and nitrite level on the physicochemical, textural and sensory properties of pork luncheon roll.

    Science.gov (United States)

    Hayes, J E; Canonico, I; Allen, P

    2013-11-01

    Nine treatments of pork luncheon roll produced with three sodium nitrite levels (0, 0.05 and 0.1%) and three tomato pulp powder (TPP) levels (0, 1.5 and 3%) were assessed at three storage times (2, 7 and 14d). The effects of enrichment with TPP on composition (protein, fat, moisture and ash), pH, colour (CIE L*, a*, b*), nitrosomyoglobin (NOMb) content, lipid oxidation (TBARS), residual nitrite content, total viable count (TVC) texture profile analysis (TPA) and sensory analysis of cooked pork luncheon roll were investigated. Decreasing the level of nitrite increased (p<0.001) the pH, the NOMb value (p<0.001), lipid oxidation (p<0.001) and the residual nitrite content (p<0.001) and affected the colour of the cooked product. The reduction in nitrites had no effect on the composition and texture of the pork luncheon rolls. Adding TPP reduced (p<0.001) the pH and increased (p<0.001) the colour parameters a* and b* of both the raw luncheon roll formulation and the cooked luncheon roll product. TPP, particularly at 3% had a detrimental effect on the texture of pork luncheon rolls by decreasing hardness (p<0.001), gumminess (p<0.001) and chewiness (p<0.001) and increasing cohesiveness (p<0.001). The TBA value increased (p<0.01) with the three main factors (nitrite, TPP, day) but was in all cases well below the 2mg MDA/kg threshold. TVCs for all treatments and storage days were below the TVC limit for this type of cooked product. The pork luncheon roll formulated with 50mg nitrite and 1.5% TPP had similar or enhanced sensory attributes compared to the luncheon roll containing no TPP and a nitrite level of 100mg/kg of product. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. 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.

  8. Lab-on-chip measurement of nitrate and nitrite for in situ analysis of natural waters.

    Science.gov (United States)

    Beaton, Alexander D; Cardwell, Christopher L; Thomas, Rupert S; Sieben, Vincent J; Legiret, François-Eric; Waugh, Edward M; Statham, Peter J; Mowlem, Matthew C; Morgan, Hywel

    2012-09-04

    Microfluidic technology permits the miniaturization of chemical analytical methods that are traditionally undertaken using benchtop equipment in the laboratory environment. When applied to environmental monitoring, these "lab-on-chip" systems could allow high-performance chemical analysis methods to be performed in situ over distributed sensor networks with large numbers of measurement nodes. Here we present the first of a new generation of microfluidic chemical analysis systems with sufficient analytical performance and robustness for deployment in natural waters. The system detects nitrate and nitrite (up to 350 μM, 21.7 mg/L as NO(3)(-)) with a limit of detection (LOD) of 0.025 μM for nitrate (0.0016 mg/L as NO(3)(-)) and 0.02 μM for nitrite (0.00092 mg/L as NO(2)(-)). This performance is suitable for almost all natural waters (apart from the oligotrophic open ocean), and the device was deployed in an estuarine environment (Southampton Water) to monitor nitrate+nitrite concentrations in waters of varying salinity. The system was able to track changes in the nitrate-salinity relationship of estuarine waters due to increased river flow after a period of high rainfall. Laboratory characterization and deployment data are presented, demonstrating the ability of the system to acquire data with high temporal resolution.

  9. Inhibition of Listeria monocytogenes using natural antimicrobials in no-nitrate-or-nitrite-added ham.

    Science.gov (United States)

    Sullivan, Gary A; Jackson-Davis, Armitra L; Niebuhr, Steven E; Xi, Yuan; Schrader, Kohl D; Sebranek, Joseph G; Dickson, James S

    2012-06-01

    Consumer demand for foods manufactured without the direct addition of chemical preservatives, such as sodium nitrite and organic acid salts, has resulted in a unique class of "naturally" cured meat products. Formulation with a natural nitrate source and nitrate-reducing bacteria results in naturally cured processed meats that possess traits similar to conventionally cured meats. However, previous research has shown that the naturally cured products are more susceptible to pathogen growth. This study evaluated Listeria monocytogenes growth on ham manufactured with natural curing methods and with commercially available clean-label antimicrobials (cultured sugar and vinegar blend; lemon, cherry, and vinegar powder blend) and assessed impacts on physicochemical characteristics of the product. Hams made with either of the antimicrobials supported L. monocytogenes growth similar to that in the traditionally cured control (P > 0.05). Hams made with prefermented celery juice powder had the lowest residual nitrite concentrations (P monocytogenes growth was similar to that of the uncured control (P > 0.05). Aside from residual nitrite and nitrate concentrations, few physicochemical differences were identified. These findings show that ham can be produced with natural curing methods and antimicrobials to provide similar L. monocytogenes inhibition and physicochemical traits as in traditionally cured ham.

  10. 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.

  11. 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

    2015-05-11

    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.

  12. Peroxynitrous-acid-induced chemiluminescence of fluorescent carbon dots for nitrite sensing.

    Science.gov (United States)

    Lin, Zhen; Xue, Wei; Chen, Hui; Lin, Jin-Ming

    2011-11-01

    In this work, chemiluminescent (CL) property of the carbon dots in the presence of peroxynitrous acid was studied. Peroxynitrous acid is formed by online mixing of nitrite and acidified hydrogen peroxide. The CL intensity was increased linearly with nitrite concentration in the range from 1.0 × 10(-7) M to 1.0 × 10(-5) M, and the detection limit was 5.3 × 10(-8) M (signal-to-noise ratio of S/N = 3). This method has been successfully applied to the determination of nitrites in pond water, river water, and pure milk, with recoveries in the range of 98%-108%. The CL mechanism of the peroxynitrous acid-carbon dots system was investigated using the CL, ultraviolet-visible light (UV-vis), and electron paramagnetic resonance (EPR) spectra. The electron-transfer annihilation of hole-injected and electron-injected carbon dots could mainly account for the CL emission, which sheds new light on the optical properties of the carbon dots.

  13. Peroxynitrous-acid-induced chemiluminescence detection of nitrite based on Microfluidic chip.

    Science.gov (United States)

    Wu, Jing; Wang, Xiong; Lin, Yitong; Zheng, Yongzan; Lin, Jin-Ming

    2016-07-01

    A chemiluminescent method for nitrite detection was developed on microfluidic chip. Carbon dots-NaNO2(-) acidified H2O2 system was adopted. Chemiluminescence (CL) spectrum of this system was detected. The radiative recombination of hole-injected and electron-injected carbon dots explained their CL property. Spiral microchannels were designed on the microfluidic chip to allow enough reaction time for the carbon dots-NaNO2-acidified H2O2 system. Carbon dots and NaNO2 were premixed in the branch microchannel, then, the mixture reacted with acidified H2O2 in spiral microchannels. Concentrations of H2SO4 and H2O2, dilution ratio of carbon dots in H2O and flow rate were optimized to obtain the best CL signals. The approach presented satisfactory linear relationship between NaNO2 concentration and CL intensity. The tolerance of metal ions in determination of 1×10(-5)M nitrite was analyzed. The nitrites in water and beverage samples were successfully analyzed on the microfluidic chip with good repeatability. The data were well accordance with the results obtained from GB 5009.33(-) 2010. This microfluidic CL detection method is believed to be a simple, automatic and agent-save approach for inorganic ion analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Nitrate and Nitrite Determination in Gunshot Residue Samples by Capillary Electrophoresis in Acidic Run Buffer.

    Science.gov (United States)

    Erol, Özge Ö; Erdoğan, Behice Y; Onar, Atiye N

    2017-03-01

    Simultaneous determination of nitrate and nitrite in gunshot residue has been conducted by capillary electrophoresis using an acidic run buffer (pH 3.5). In previously developed capillary electrophoretic methods, alkaline pH separation buffers were used where nitrite and nitrate possess similar electrophoretic mobility. In this study, the electroosmotic flow has been reversed by using low pH running buffer without any additives. As a result of reversing the electroosmotic flow, very fast analysis has been actualized, well-defined and separated ion peaks emerge in less than 4 min. Besides, the limit of detection was improved by employing large volume sample stacking. Limit of detection values were 6.7 and 4.3 μM for nitrate and nitrite, respectively. In traditional procedure, mechanical agitation is employed for extraction, while in this work the extraction efficiency of ultrasound mixing for 30 min was found sufficient. The proposed method was successfully applied to authentic gunshot residue samples. © 2016 American Academy of Forensic Sciences.

  15. Impact of influent characteristics on a partial nitritation SBR treating high nitrogen loaded wastewater.

    Science.gov (United States)

    Ganigué, R; Volcke, E I P; Puig, S; Balaguer, M D; Colprim, J

    2012-05-01

    The Anammox process allows a sustainable treatment of wastewater with high nitrogen content. Partial oxidation of ammonium to nitrite is a previous and crucial step. Given the variability on wastewater composition, the operation of sequencing batch reactors (SBR) for partial nitritation (PN) is very challenging. This work assessed the combined influence of influent characteristics and process loading rate. Simulation results showed that wastewater composition - Total nitrogen as ammonia (TNH) and total inorganic carbon (TIC) - as well as nitrogen loading rate (NLR) govern the outcomes of the reactor. A suitable effluent can be produced when treating wastewater with different ammonia levels, as long as the TIC:TNH influent molar ratio is around 1:1 and extreme NLR are avoided. The influent pH has a key impact on nitrite conversion by governing the CO(2)-bicarbonate-carbonate equilibrium. Finally, results showed that oxidation of biodegradable organic matter produces CO(2), which acidifies the media and limits process conversion. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Comparative Study on Corrosion Protection of Reinforcing Steel by Using Amino Alcohol and Lithium Nitrite Inhibitors

    Science.gov (United States)

    Lee, Han-Seung; Ryu, Hwa-Sung; Park, Won-Jun; Ismail, Mohamed A.

    2015-01-01

    In this study, the ability of lithium nitrite and amino alcohol inhibitors to provide corrosion protection to reinforcing steel was investigated. Two types of specimens—reinforcing steel and a reinforced concrete prism that were exposed to chloride ion levels resembling the chloride attack environment—were prepared. An autoclave accelerated corrosion test was then conducted. The variables tested included the chloride-ion concentration and molar ratios of anti-corrosion ingredients in a CaOH2-saturated aqueous solution that simulated a cement-pore solution. A concentration of 25% was used for the lithium nitrite inhibitor LiNO2, and an 80% solution of dimethyl ethanolamine ((CH3)2NCH2CH2OH, hereinafter DMEA) was used for the amino alcohol inhibitor. The test results indicated that the lithium nitrite inhibitor displayed anti-corrosion properties at a molar ratio of inhibitor of ≥0.6; the amino alcohol inhibitor also displayed anti-corrosion properties at molar ratios of inhibitor greater than approximately 0.3. PMID:28787936

  17. 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.

  18. Comparative Study on Corrosion Protection of Reinforcing Steel by Using Amino Alcohol and Lithium Nitrite Inhibitors.

    Science.gov (United States)

    Lee, Han-Seung; Ryu, Hwa-Sung; Park, Won-Jun; Ismail, Mohamed A

    2015-01-14

    In this study, the ability of lithium nitrite and amino alcohol inhibitors to provide corrosion protection to reinforcing steel was investigated. Two types of specimens-reinforcing steel and a reinforced concrete prism that were exposed to chloride ion levels resembling the chloride attack environment-were prepared. An autoclave accelerated corrosion test was then conducted. The variables tested included the chloride-ion concentration and molar ratios of anti-corrosion ingredients in a CaOH₂-saturated aqueous solution that simulated a cement-pore solution. A concentration of 25% was used for the lithium nitrite inhibitor LiNO₂, and an 80% solution of dimethyl ethanolamine ((CH₃)₂NCH₂CH₂OH, hereinafter DMEA) was used for the amino alcohol inhibitor. The test results indicated that the lithium nitrite inhibitor displayed anti-corrosion properties at a molar ratio of inhibitor of ≥0.6; the amino alcohol inhibitor also displayed anti-corrosion properties at molar ratios of inhibitor greater than approximately 0.3.

  19. 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.

  20. Salivary Surrogates of Plasma Nitrite and Catecholamines during a 21-Week Training Season in Swimmers

    Science.gov (United States)

    Díaz Gómez, Miguel Mauricio; Bocanegra Jaramillo, Olga Lucia; Teixeira, Renata Roland; Espindola, Foued Salmen

    2013-01-01

    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. PMID:23700456

  1. 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.

  2. 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.

  3. Nitrification rates, nitrite and nitrate distribution in the Almeria-Oran frontal systems (eastern Alboran Sea)

    Science.gov (United States)

    Bianchi, M.; Morin, P.; Le Corre, P.

    1994-08-01

    In the western Mediterranean Sea, the Almeria-Oran frontal zone constitutes the eastern boundary of the Alboran Sea. During the "Almofront-1" cruise (April-May 1991) physical, chemical and biological features of the front and surrounding Atlantic and Mediterranean Waters were investigated. In the present study, the nitrite and nitrate concentrations and nitrification rates were measured. The nitracline was close to the surface in the north, close to the Spanish coast and in the south on the left side of the jet. The highest concentration of nitrite (0.25 μM) was located in the incoming Atlantic Waters. The ammonium oxidation rates were from 0 to 16 nmol 1 -1 d -1, except in Atlantic Waters in which the rates reached 28-42 nmol 1 -1 d -1. For all types of superficial water, i.e. Atlantic, jet core, Mediterranean, the nitrite produced by nitrification could account for the in situ concentrations in less time than the ages of the water masses. In contrast, to reach the ambient concentration, the production of nitrate would need more time than the lifetime of the water masses, except for the Atlantic Waters. In these Atlantic Waters, showing an increased rate of nitrate production, the in situ concentration of nitrate would be reached within its lifetime. The contribution of the nitrate produced by nitrification to the nitrate uptake by primary producers was estimated to range from 7% (Mediterranean Waters) to 40% (Atlantic Waters).

  4. 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 (P<0.05) converted cured pigment than the barrier bag treatments but less (P<0.05) than the control. The processing 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.

  5. Antitumor effect of synergistic contribution of nitrite and hydrogen peroxide in the plasma activated medium

    Science.gov (United States)

    Kurake, Naoyuki; Tanaka, Hiromasa; Ishikawa, Kenji; Nakamura, Kae; Kajiyama, Hiroaki; Kikkawa, Fumiaki; Kondo, Takashi; Mizuno, Masaaki; Takeda, Keigo; Kondo, Hiroki; Sekine, Makoto; Hori, Masaru

    2015-09-01

    Non-equilibrium atmospheric pressure plasmas (NEAPP) have been attracted attention in the noble application of cancer therapy. Although good effects of the Plasma-Activated-Medium (PAM) such as the selective antitumor effect and killing effect for the anticancer agent resistant cells were reported, a mechanism of this effect has not been still clarified yet. In this study, we have investigated a contribution of the reactive nitrogen and oxygen species (RNOS) generated in PAM such as hydrogen peroxide and nitrite. Those species generated in the PAM quantitatively measured by light absorbance of commercial regent. Moreover, viable cell count after cell culture with those RNOS intentionally added medium or PAM were also measured by MTS assay. Our NEAPP source generated hydrogen peroxide and nitrite with the generation ratio of 0.35 μM/s and 9.8 μM/s. In those RNOS, hydrogen peroxide has respective antitumor effect. On the other hands, nitrite has no antitumor effect singly. But, synergistically enhance the antitumor effect of hydrogen peroxide. Moreover, this effect of those RNOS also contribute for the selectively cancer killing effect of PAM.

  6. Integrating landfill bioreactors, partial nitritation and anammox process for methane recovery and nitrogen removal from leachate

    Science.gov (United States)

    Sun, Faqian; Su, Xiaomei; Kang, Tingting; Wu, Songwei; Yuan, Mengdong; Zhu, Jing; Zhang, Xiayun; Xu, Fang; Wu, Weixiang

    2016-06-01

    A new process consisting of a landfill bioreactor, partial-nitritation (PN) and the anammox process has been developed for landfill leachate treatment. In this study, the landfill bioreactor exhibited excellent performance in methane-rich biogas recovery, with a specific biogas yield of 0.47 L gas g-1 COD and methane percentages of 53-76%. PN was achieved in the aerobic reactor by high free ammonia (101 ± 83 mg NH3 L-1) inhibition for nitrite-oxidizing bacteria, and the desired PN effluent composition (effluent nitrite: ammonium ratio of 1.1 ± 0.3) was controlled by adjusting the alkalinity concentration per unit of ammonium oxidized to approximately 14.3 mg CaCO3 mg-1 N in the influent. The startup of anammox process was successfully achieved with a membrane bioreactor in 160 d, and a maximum nitrogen removal rate of 216 mg N L-1 d-1 was attained for real landfill leachate treatment. The quantitative polymerase chain reaction results confirmed that the cell-specific anammox activity was approximately 68-95 fmol N cell-1 d-1, which finally led to the stable operation of the system.

  7. 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.

  8. 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 (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 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 N2O production was low (∼2% of the oxidized ammonium). Net N2O production rates transiently increased with a rise in pH after each feeding, suggesting a potential effect of pH on N2O production. In situ application of 15N labeled substrates revealed nitrifier denitrification as the dominant pathway of N2O production. Our study highlights operational conditions that minimize N2O emission from two-stage autotrophic nitrogen removal systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. The impact of nitrite and antioxidants on ultraviolet-A-induced cell death of human skin fibroblasts.

    Science.gov (United States)

    Opländer, Christian; Cortese, Miriam M; Korth, Hans-Gert; Kirsch, Michael; Mahotka, Csaba; Wetzel, Wiebke; Pallua, Norbert; Suschek, Christoph V

    2007-09-01

    Nitrite (NO(2)(-)) occurs ubiquitously in biological fluids such as blood and sweat. Ultraviolet A-induced nitric oxide formation via decomposition of cutaneous nitrite, accompanied by the production of reactive oxygen (ROS) or nitrogen species (RNS), represents an important source for NO in human skin physiology. Examining the impact of nitrite and the antioxidants glutathione (GSH), Trolox (TRL), and ascorbic acid (ASC) on UVA-induced toxicity of human skin fibroblasts (FB) we found that NO(2)(-) concentration-dependently enhances the susceptibility of FB to the toxic effects of UVA by a mechanism comprising enhanced induction of lipid peroxidation. While ASC completely protects FB cultures from UVA/NO(2)(-)-induced cell damage, GSH or TRL excessively enhances UVA/NO(2)(-)-induced cell death by a mechanism comprising nitrite concentration-dependent TRL radical formation or GSH-derived oxidative stress. Simultaneously, in the presence of GSH or TRL the mode of UVA/NO(2)(-)-induced cell death changes from apoptosis to necrosis. In summary, during photodecomposition of nitrite, ROS or RNS formation may act as strong toxic insults. Although inhibition of oxidative stress by NO and other antioxidants represents a successful strategy for protection from UVA/NO(2)(-)-induced injuries, GSH and TRL may nitrite-dependently aggravate the injurious impact by TRL or GSH radical formation, respectively.

  10. 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

    2018-02-15

    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 0.4μM. It was found that, after being quenched by nitrite ion, these composite samples could be reclaimed and recovered by sulphamic acid, confirming their recyclability. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Migration of nitrate, nitrite, and ammonia through the municipal solid waste incinerator bottom ash layer in the simulated landfill.

    Science.gov (United States)

    Yao, Jun; Chen, Luxi; Zhu, Huayue; Shen, Dongsheng; Qiu, Zhanhong

    2017-04-01

    Simulated landfill was operated for 508 days to investigate the effect of municipal solid waste incinerator (MSWI) bottom ash layer on the migration of nitrate, nitrite, and ammonia when it was used as the intermediate layer in the landfill. The result suggested that the MSWI bottom ash layer could capture the nitrate, nitrite, and ammonia from the leachate. The adsorption of the nitrate, nitrite, and ammonia on the MSWI bottom ash layer was saturated at the days 396, 34, and 97, respectively. Afterwards, the nitrogen species were desorbed from the MSWI bottom ash layer. Finally, the adsorption and desorption could reach the equilibrium. The amounts of adsorbed nitrate and nitrite on the MSWI bottom ash layer were 1685.09 and 7.48 mg, respectively, and the amount of the adsorbed and transformed ammonia was 13,773.19 mg, which was much higher than the desorbed. The water leaching test and synthetic precipitation leaching procedure (SPLP) results showed that the leachable nitrate, nitrite, and ammonia in the MSWI bottom ash were greatly increased after the landfill operation, suggesting that the adsorbed nitrogen could be finally leached out. Besides, the results also showed that MSWI bottom ash layer could affect the release of nitrate and ammonia at the initial stage of the landfill. However, it had little effect on the release of nitrite.

  12. 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.

  13. An observational prospective study of topical acidified nitrite for killing methicillin-resistant Staphylococcus aureus (MRSA in contaminated wounds

    Directory of Open Access Journals (Sweden)

    Ferguson Gail P

    2011-10-01

    Full Text Available Abstract Background Endogenous nitric oxide (NO kills bacteria and other organisms as part of the innate immune response. When nitrite is exposed to low pH, NO is generated and has been used as an NO delivery system to treat skin infections. We demonstrated eradication of MRSA carriage from wounds using a topical formulation of citric acid (4.5% and sodium nitrite (3% creams co-applied for 5 days to 15 wounds in an observational prospective pilot study of 8 patients. Findings Following treatment with topical citric acid and sodium nitrite, 9 of 15 wounds (60% and 3 of 8 patients (37% were cleared of infection. MRSA isolates from these patients were all sensitive to acidified nitrite in vitro compared to methicillin-sensitive S. aureus and a reference strain of MRSA. Conclusions Nitric oxide and acidified nitrite offer a novel therapy for control of MRSA in wounds. Wounds that were not cleared of infection may have been re-contaminated or the bioavailability of acidified nitrite impaired by local factors in the tissue.

  14. Osteoporosis, calcium and physical activity.

    OpenAIRE

    Martin, A. D.; Houston, C S

    1987-01-01

    Sales of calcium supplements have increased dramatically since 1983, as middle-aged women seek to prevent or treat bone loss due to osteoporosis. However, epidemiologic studies have failed to support the hypothesis that larger amounts of calcium are associated with increased bone density or a decreased incidence of fractures. The authors examine the evidence from controlled trials on the effects of calcium supplementation and physical activity on bone loss and find that weight-bearing activit...

  15. 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.

  16. Laser Sintered Calcium Phosphate Bone

    National Research Council Canada - National Science Library

    Vail, Neil

    1999-01-01

    ...) technology selective laser sintering (SLS). BME has successfully implemented a pilot facility to fabricate calcium phosphate implants using anatomical data coupled with the selective laser sintering process...

  17. [Determination of trace amounts of nitrite and its chemical reaction kinetics].

    Science.gov (United States)

    Luo, Zhi-yong; Zheng, Huai-li

    2014-06-01

    A catalytic kinetic spectrophotometric method for the determination of nitrite, NO2(-)-S2O8(2-)-MR, was developed. It is based on the fading reaction of methyl red (MR) oxidized by potassium persulfate which can be catalyzed by NO2- in the medium of dilute HCl. The optimum experimental conditions were gained by combining single factor experiments with orthogonal experiments. Calibration curve, detection limit, precision, and anti-interference under the optimum experimental conditions were researched. Its kinetics principles and parameters were discussed. Its quantitative principle was investigated. The results show that the optimum experimental conditions of this method should be as follows: 1.0 mL 0.3 mol x L(-1) HCl, 1.0 mL 0.01 mol x L(-1) K2S2O8, 0.6 mL 0.2 g x L(-1) MR, reaction temperature 80 degrees C and reaction time 9 min. The principles for the quantitative determination of trace nitrite is that variation of MR concentration at the maximum absorption wavelength of 518 nm, ln(A0/A), shows a good linear relationship with the concentration of NO2- under the optimum experimental conditions. Its determination range is 0.01-0.80 mg x L(-1) and its detection limit is 0.007 mg x L(-1). The kinetic characteristics are that the reaction order in NO2- is 1 and the fading reaction is a pseudo first order reaction. Its apparent activation energy is 85.04 kJ x mol(-1). Its apparent rate constant is 0.021 4 min(-1), and the half-life is 32.39 min at 80 degrees C. The kinetic principle is that the variation of MR concentration is directly proportional to the concentration of NO2-, ln(A0/A) = kc(NO2-). This new method for the determination of trace nitrite has never previously been reported in the published literature so far. It is highly sensitive and selective. Most of the common ions don't interfere with the determination of nitrite. This method has the advantages of convenient operation and the regents used are cheap and nontoxic. It was applied to the determination

  18. 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

  19. 21 CFR 73.1070 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... precipitated calcium carbonate (CaCO3). (2) Color additive mixtures for drug use made with calcium carbonate... precipitated calcium carbonate in the United States Pharmacopeia XX (1980). (c) Uses and restrictions. Calcium... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Calcium carbonate. 73.1070 Section 73.1070 Food...

  20. 21 CFR 184.1191 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium carbonate. 184.1191 Section 184.1191 Food... Specific Substances Affirmed as GRAS § 184.1191 Calcium carbonate. (a) Calcium carbonate (CaCO3, CAS Reg... soda process”; (2) By precipitation of calcium carbonate from calcium hydroxide in the “Carbonation...

  1. Calcium signalling: fishing out molecules of mitochondrial calcium transport.

    Science.gov (United States)

    Hajnóczky, György; Csordás, György

    2010-10-26

    Cellular energy metabolism, survival and death are controlled by mitochondrial calcium signals originating in the cytoplasm. Now, RNAi studies link three proteins - MICU1, NCLX and LETM1 - to the previously unknown molecular mechanism of mitochondrial calcium transport. Copyright © 2010 Elsevier Ltd. All rights reserved.

  2. Calcium electroporation in three cell lines; a comparison of bleomycin and calcium, calcium compounds, and pulsing conditions

    DEFF Research Database (Denmark)

    Frandsen, Stine Krog; Gissel, Hanne; Hojman, Pernille

    2013-01-01

    BACKGROUND: Electroporation with calcium (calcium electroporation) can induce ATP depletion-associated cellular death. In the clinical setting, the cytotoxic drug bleomycin is currently used with electroporation (electrochemotherapy) for palliative treatment of tumors. Calcium electroporation off...

  3. 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 ...

  4. 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 ...

  5. 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.

  6. 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.

  7. 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 (p<0.001 and =0.017 for nitrate 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

  8. Stable prenucleation calcium carbonate clusters.

    Science.gov (United States)

    Gebauer, Denis; Völkel, Antje; Cölfen, Helmut

    2008-12-19

    Calcium carbonate forms scales, geological deposits, biominerals, and ocean sediments. Huge amounts of carbon dioxide are retained as carbonate ions, and calcium ions represent a major contribution to water hardness. Despite its relevance, little is known about the precipitation mechanism of calcium carbonate, and specified complex crystal structures challenge the classical view on nucleation considering the formation of metastable ion clusters. We demonstrate that dissolved calcium carbonate in fact contains stable prenucleation ion clusters forming even in undersaturated solution. The cluster formation can be characterized by means of equilibrium thermodynamics, applying a multiple-binding model, which allows for structural preformation. Stable clusters are the relevant species in calcium carbonate nucleation. Such mechanisms may also be important for the crystallization of other minerals.

  9. 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

  10. 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.

  11. The nitric oxide reductase activity of cytochrome c nitrite reductase from Escherichia coli.

    Science.gov (United States)

    van Wonderen, Jessica H; Burlat, Bénédicte; Richardson, David J; Cheesman, Myles R; Butt, Julea N

    2008-04-11

    Cytochrome c nitrite reductase (NrfA) from Escherichia coli has a well established role in the respiratory reduction of nitrite to ammonium. More recently the observation that anaerobically grown E. coli nrf mutants were more sensitive to NO. than the parent strain led to the proposal that NrfA might also participate in NO. detoxification. Here we describe protein film voltammetry that presents a quantitative description of NrfA NO. reductase activity. NO. reduction is initiated at similar potentials to NrfA-catalyzed reduction of nitrite and hydroxylamine. All three activities are strongly inhibited by cyanide. Together these results suggest a common site for reduction of all three substrates as axial ligands to the lysine-coordinated NrfA heme rather than nonspecific NO. reduction at one of the four His-His coordinated hemes also present in each NrfA subunit. NO. reduction by NrfA is described by a K(m) of the order of 300 microm. The predicted turnover number of approximately 840 NO. s(-1) is much higher than that of the dedicated respiratory NO. reductases of denitrification and the flavorubredoxin and flavohemoglobin of E. coli that are also proposed to play roles in NO. detoxification. In considering the manner by which anaerobically growing E. coli might detoxify exogenously generated NO. encountered during invasion of a human host it appears that the periplasmically located NrfA should be effective in maintaining low NO. levels such that any NO. reaching the cytoplasm is efficiently removed by flavorubredoxin (K(m) approximately 0.4 microm).

  12. Mammalian nitrate biosynthesis: mouse macrophages produce nitrite and nitrate in response to Escherichia coli lipopolysaccharide

    Energy Technology Data Exchange (ETDEWEB)

    Stuehr, D.J.; Marletta, M.A.

    1985-11-01

    Escherichia coli lipopolysaccharide (LPS)-induced nitrate biosynthesis was studied in LPS-sensitive C3H/He and LPS-resistant C3H/HeJ mice. Intraperitoneal injection of 15 ..mu..g of LPS led to a temporary 5- to 6-fold increase in blood nitrate concentration in the C3H/He strain. Levels of nitrate excreted in the urine were also increased. In contrast, no increase was observed in the C3H/HeJ strain with LPS injections up to 175 ..mu..g. Furthermore, thioglycolate-elicited peritoneal macrophages from C3H/He, but not from C3H/HeJ mice, produced nitrite (60%) and nitrate (40%) when cultured with LPS (10 ..mu..g/ml). T-lymphocyte addition/depletion experiments showed the presence of T cells enhanced this response. However, LPS did not cause nitrite or nitrate production in cultures of spleen lymphocytes from either strain. LPS-induced nitrate synthesis was also observed with nude mice and CBA/N mice, indicating that neither functional T lymphocytes nor LPS-responsive B lymphocytes were required for the response in vivo. This was consistent with the in vitro results showing macrophages alone were competent. Mycobacterium bovis infection of C3H/He and C3H/HeJ mice resulted in a large increase in nitrate production over the course of the infection for both strains, suggesting T-lymphocyte-mediated activation of macrophages as a potent stimulus for nitrate biosynthesis. The synthesis of nitrite is significant in that it can directly participate in the endogenous formation of nitrosamines and may also be involved in some aspect of the chemistry of cytotoxicity.

  13. Organic removal by denitritation and methanogenesis and nitrogen removal by nitritation from landfill leachate.

    Science.gov (United States)

    Peng, Yongzhen; Zhang, Shujun; Zeng, Wei; Zheng, Shuwen; Mino, Takashi; Satoh, Hiroyasu

    2008-02-01

    A system consisting of a two-stage UASB and anoxic-oxic reactor was used to enhance COD and nitrogen removal from landfill leachate. To improve denitrification efficiency, the raw leachate with recycled final effluent was pumped into the first-stage UASB (UASB1) to carry out simultaneous denitrification and methanogenesis. The results over 180 d show that the maximum organic removal rate in UASB1 and UASB2 was 12.5 and 8.5 kgCODm(-3)d(-1) in the oxic zone of the A/O reactor, respectively. The COD and biochemical oxygen demand (BOD5) removal efficiency of the system was 80-92% and about 99%, respectively. Without controlling temperature (17-30 degrees C) and dissolved oxygen (0.5-4.0 mgL(-1)), the maximum NH4+-N removal rate was 0.68 kg NH4+-Nm(-3)d(-1), and about 99% of NH4+-N removal was obtained by nearly complete nitritation. The 81-93% total nitrogen removal was obtained by complete denitrification in the UASB1 and in the anoxic zone of the A/O reactor. Fluorescence in situ hybridization (FISH) analysis of the sludge samples from A/O reactor showed that ammonia oxidizing bacteria (AOB) consisted 4% of the eubacterium, while nitrite oxidizing bacteria (NOB) counted less than 0.2% of that. The study shows that the main factors achieving and maintaining nitritation are a proper range of free ammonia concentration obtained by dilution recycled final effluent that inhibits NOB but not AOB; effective control on aeration time by indication of "ammonia valley" on pH profile; and highly efficient denitrification and its reproducing alkalinity to result in pH above 8.5.

  14. Influence of low levels of water salinity on toxicity of nitrite to anuran larvae.

    Science.gov (United States)

    Shinn, C; Marco, A; Serrano, L

    2013-08-01

    Reactive nitrogen compounds such as nitrite (NO2(-)) are highly toxic to aquatic animals and are partly responsible for the global decline of amphibians. On some fish and Caudata amphibian species low levels of sodium chloride significantly reduce the toxicity of nitrite. However, the nitrite-salinity interaction has not been properly studied in anuran amphibians. To verify if chloride (Cl(-)) attenuates NO2(-) toxicity, eggs and larvae of three anuran species were subjected to a series of NO2(-) solutions combined with three salt concentrations (0, 0.4 and 2 or 0, 0.052 and 0.2gL(-1)NaCl). One of the species tested originated from two different populations inhabiting highly contrasted nutrient richness environments: lowland Doñana Natural Park and Sierra de Gredos Mountain. In general, the presence of Cl(-) increased survival and growth of lowland Pelophylax perezi and activity of mountain P. perezi larvae exposed to NO2(-), thus attenuating the toxicity of NO2(-) to developing amphibians. Mountain amphibian populations appeared to be much more sensitive to the concentrations of NO2(-) and Cl(-) used in this experiment than coastal conspecifics, suggesting possible adaptation of populations to local conditions. Nitrogen pollution in coastal wetlands poses a serious threat to aquatic organisms, causing direct toxicity or indirect effects via ecosystem eutrophication. The presence of low to medium levels of salinity that would be common in coastal wetlands may attenuate the direct effects of increasing concentrations of nitrogenous compounds in water bodies. Furthermore, treating cultures of endangered anurans with small amounts of NaCl may provide an additional protective measure. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. 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

  16. The Intersection of NO and H2S: Persulfides Generate NO from Nitrite through Polysulfide Formation.

    Science.gov (United States)

    Bailey, T Spencer; Henthorn, Hillary A; Pluth, Michael D

    2016-12-19

    Hydrogen sulfide (H2S) and nitric oxide (NO) are important biosignaling molecules, and their biochemistries are increasingly recognized to be intertwined. Persulfides are an oxidized product of biological H2S and have emerged as important species involved in the biological action of reactive sulfur species. Using isolated persulfides, we employed a combination of experimental and computational methods to investigate the contribution of persulfides to H2S/NO crosstalk. Our studies demonstrate that isolated persulfides react with nitrite to produce NO via polysulfide and perthionitrite intermediates. These results highlight the importance of persulfides, polysulfides, and perthionitrite as intertwined reactive nitrogen and sulfur species.

  17. Monoclonal antibodies recognizing nitrite oxidoreductase of Nitrobacter hamburgensis, N. winogradskyi, and N. vulgaris.

    OpenAIRE

    Aamand, J; Ahl, T; Spieck, E.

    1996-01-01

    Three monoclonal antibodies (MAbs) against nitrite oxidoreductase (NOR) of Nitrobacter hamburgensis were produced. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting analysis of the purified enzyme showed that the MAbs named Hyb 153.1 and Hyb 153.3 both recognized a protein with a molecular mass of 64,000 Da, while Hyb 153.2 recognized a protein with a molecular mass of 115,000 Da. The molecular masses of these proteins are in the same range as those of the proteins ...

  18. Nitrite-Oxidizing Bacterium Nitrobacter winogradskyi Produces N-Acyl-Homoserine Lactone Autoinducers

    OpenAIRE

    Brett L. Mellbye; Bottomley, Peter J.; Sayavedra-Soto, Luis A.

    2015-01-01

    Nitrobacter winogradskyi is a chemolithotrophic bacterium that plays a role in the nitrogen cycle by oxidizing nitrite to nitrate. Here, we demonstrate a functional N-acyl-homoserine lactone (acyl-HSL) synthase in this bacterium. The N. winogradskyi genome contains genes encoding a putative acyl-HSL autoinducer synthase (nwi0626, nwiI) and a putative acyl-HSL autoinducer receptor (nwi0627, nwiR) with amino acid sequences 38 to 78% identical to those in Rhodopseudomonas palustris and other Rhi...

  19. Comparative diagnosis of urinary tract infection (UTI using urinary nitrite and significant bacteriuria (SBU

    Directory of Open Access Journals (Sweden)

    John Anuli S

    2016-04-01

    Full Text Available The clinical laboratory diagnosis of urinary tract infection was compared in two hundred (200 midstream urine samples using bacteria culture and urinary nitrite detection technique. The comparative susceptibility of the isolates to common antibiotics was evaluated using completely randomized design (CRD. The minimum inhibitory concentration (MIC and minimum bactericidal concentration (MBC for each antibiotics test was evaluated using standard laboratory procedures. Approximately fifty one percent (101/200 of urine samples that were culture yielded significant bacteriuria (SBU as compared to (32.59%, 65/200 which had positive nitrite detection. Also eighteen percent (18%, 35/200 of the negative nitrite detection test showed evidence of significant bacteriuria. Significant bacteriuria was significantly associated at p<0.05 with culture isolation technique. A total of nine (9 different bacterial isolates were detected in this study. The isolates and their frequency of occurrence were Escherichia coli 30(29.7%, Pseudomonas aeruginosa 15(14.9%, Klebsiella pneumonia 13(12.8%, Enterococcus faecalis and Citrobacterfreundii 10(9.9, Proteus mirabilis 9(8.9, Staphylococcus aureus 8(7.7%, Serretiamarcesens and Streptococcus specie 3(3.0%.The mean total viable count ranged from 31.50±3.15x10 7 cfuml-1 to 262.5±1.09x10 8 cfuml-1. The antibiotics susceptibility profile reveals a high level of susceptibility of most isolates to Gentamycin(50%, Ciprofloxacin(83%, Tarivid(100%, Augumentin(50% and Levofloxacin(100% with mean zone of inhibition ranging from 18.6mm to 20.3mm. However, high resistance profile of hundred percent was observed with nalidixic acid, ampicillin and septrin while reflacin resistant rate was 66.7%. Intermediary susceptibility was observed with streptomycin (50% and ceporex (66.7%. This study therefore reveals the diagnostic superiority of culture method to urinary nitrite detection technique. In addition, it also reveals Escherichia coli

  20. Voltammetry and Electrocatalysis of Achrornobacter Xylosoxidans Copper Nitrite Reductase on Functionalized Au(111)-Electrode Surfaces

    DEFF Research Database (Denmark)

    Welinder, Anna C.; Zhang, Jingdong; Hansen, Allan G.

    2007-01-01

    planar electrode surfaces is a step towards the resolution of this central issue. We report here the voltammetry of copper nitrite reductase (CNiR, Achromobacter xylosoxidons) on Au(111)-electrode surfaces modified by monolayers of a broad variety of thiol-based linker molecules. These represent......NiR thus shows highly efficient, close to ideal reversible electrocatalytic voltammetry on cysteamine-covered Au(111)-electrode surfaces, most likely due to two cysteamine orientations previously disclosed by in situ scanning tunnelling microscopy. Such a dual orientation exposes both a hydrophobic...

  1. The use of ionic chromatography in determining the contamination of sugar by-products by nitrite and nitrate.

    Science.gov (United States)

    Antczak-Chrobot, Aneta; Bąk, Paulina; Wojtczak, Maciej

    2018-02-01

    In 2010, the Directive on undesirable substances in animal feed entered into force and for the first time was laid down a maximum limit for nitrite content in sugar industry feed materials such as molasses and beet pulp. Due to a lack of suitable analytical methods for nitrite determination, this study was developed with the aim to standardize a nitrite analytical method in by-products from sugar industry. In this study high performance anion exchange chromatography with conductometric detection was used for determining nitrite and nitrate content of sugar by-products included in feed material. The study confirms the usefulness of the applied ion chromatographic method for the evaluation of the content of nitrite and nitrate in sugar by-products. The results showed that in many samples of beet pulp and molasses the content of "undesirable substances for animal feed" was below 15mgkg-1 (expressed as sodium nitrate at 12% of moisture). Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Influence of iron sulfides on abiotic oxidation of UO2 by nitrite and dissolved oxygen in natural sediments.

    Science.gov (United States)

    Carpenter, Julian; Bi, Yuqiang; Hayes, Kim F

    2015-01-20

    Iron sulfide precipitates formed under sulfate reducing conditions may buffer U(IV) insoluble solid phases from reoxidation after oxidants re-enter the reducing zone. In this study, sediment column experiments were performed to quantify the effect of biogenic mackinawite on U(IV) stability in the presence of nitrite or dissolved oxygen (DO). Two columns, packed with sediment from an abandoned U contaminated mill tailings site near Rifle, CO, were biostimulated for 62 days with an electron donor (3 mM acetate) in the presence (BRS+) and absence (BRS−) of 7 mM sulfate. The bioreduced sediment was supplemented with synthetic uraninite (UO2(s)), sterilized by gamma-irradiation, and then subjected to a sequential oxidation by nitrite and DO. Biogenic iron sulfides produced in the BRS+ column, mostly as mackinawite, inhibited U(IV) reoxidation and mobilization by both nitrite and oxygen. Most of the influent nitrite (0.53 mM) exited the columns without oxidizing UO2, while a small amount of nitrite was consumed by iron sulfides precipitates. An additional 10-day supply of 0.25 mM DO influent resulted in the release of about 10% and 49% of total U in BRS+ and BRS– columns, respectively. Influent DO was effectively consumed by biogenic iron sulfides in the BRS+ column, while DO and a large U spike were detected after only a brief period in the effluent in the BRS– column.

  3. Behavior of Staphylococcus aureus and autochthone microbiota in fresh sausages added of sodium nitrite and stored under refrigeration

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    Lucyanne Maria Moraes Correia

    2014-10-01

    Full Text Available Fresh sausages are cured meat products that may be contaminated with Staphylococcus aureus during the manufacturing procedure, which is frequently related with inadequate handling practices. The use of nitrite in meat products has proven efficacy against Clostridium botulinum, and studies indicate that bactericidal action against S. aureus depends on factors that are intrinsic and extrinsic to the product. The objective of the present study was to evaluate the effect of nitrite concentration, and pH on S. aureus and psychrotrophic autochthone microbiota in fresh sausages stored at different times and temperatures. Fresh sausage were produced at nitrite concentrations 50, 150 and 200ppm and contaminated with S. aureus. The sausages were storage at refrigeration (7 and 12°C and the quantification of S. aureus and psychrotrophic microorganisms was carried out on days 0, 2, 4, 7, and 10. Results showed that nitrite concentrations and the temperatures used had minimal effect on the multiplication of S. aureus and psychrotrophic autochthone microbiota. Final counts depended only on the length of storage: at the end of 10 days, counts were statistically similar in the different groups, showing that temperature and nitrite concentrations used did not control microbial growth effectively. It is suggested that the product should be stored below 7°C or at freezing temperatures for greater microbiological stability

  4. Spectrophotometric determination of nitrite based on its catalytic effect on the reaction of nuclear fast red and potassium bromate

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    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.

  5. Nitrite inhibition of Vitreoscilla hemoglobin (VHb) in recombinant E. coli: direct evidence that VHb enhances recombinant protein production.

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    Aydin, S; Webster, D A; Stark, B C

    2000-01-01

    Bacteria engineered with the gene (vgb) encoding Vitreoscilla hemoglobin (VHb) typically produce more protein than unengineered cells, and it has generally been assumed that VHb is responsible for this effect. Here, using matched strains of E. coli that bear a recombinant alpha-amylase gene (MK57) or the alpha-amylase gene and vgb (MK79), we provide evidence supporting this assumption. Sodium nitrite (which is known to inhibit heme proteins) was tested over a range of concentrations regarding effects on growth, alpha-amylase production, respiration, and VHb function in MK57 and MK79. Nitrite concentrations were identified at which respiration of cell membranes was inhibited only slightly and to approximately equal degrees in both strains, while whole cell respiration was inhibited to a greater extent and about twice as much in MK79 as MK57. This suggests that these concentrations inhibit VHb while having a much smaller effect on cytochrome oxidase. Direct measurements of VHb showed, in fact, that the same nitrite concentrations greatly decreased the levels of active (ferrous) and, to a somewhat lesser extent, total (ferrous plus ferric) VHb in MK79. Finally, these same nitrite concentrations reversed the advantage regarding alpha-amylase production of MK79 over MK57 seen at 0 mM nitrite, linking the presence of active VHb with the increase in alpha-amylase production.

  6. FREE RADICALS AND INFLAMMATION IN RATS OF DIFFERENT AGE IN CASES OF SODIUM NITRITES AND TOBACCO SMOKE POISONING

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    P. H. Lykhatskyy

    2017-07-01

    Full Text Available Background. Due to the wide use of nitrate fertilizers in agriculture and their migration into groundwater and food, the spreading of nitrate poisoning has become epidemic. However, people in the process of life get into bad habits: smoking, alcohol, drugs abuse. All these factors affect health and can cause fatal outcome. In real life, people are often exposed to more toxic factors that lead to general poisoning of the body and damage of many organs. Objective. The research was aimed to study the activity of free radicals and inflammation in rats of different age in cases of sodium nitrite affection with underlying 45-day tobacco intoxication. Methods. The content of nitrite ion (NO2- was evaluated by Gris reaction. The level of pro-inflammatory (interleukin 6 (IL-6 and anti-inflammatory (interleukin 4 (IL-4 cytokines was determined in serum by ELISA method using test kits. Results. It was proved that in rats of different age affected by sodium nitrite with underlying 45-day tobacco smoke intoxication, the content of nitrite ion in serum, liver, lungs and myocardium is increased. After poisoning the animals with the studied toxicants, inflammation was activated in the body that was evidenced by the increased pro-inflammatory cytokine IL-6 and decreased inflammatory cytokine IL-4 in serum. Conclusions. The nitrite ion content in organs was the most significant and inflammation was manifested in the immature rats. In these animals the content of anti-inflammatory cytokines was the lowest.

  7. Calcium metabolism & hypercalcemia in adults.

    Science.gov (United States)

    Lumachi, F; Motta, R; Cecchin, D; Ave, S; Camozzi, V; Basso, S M M; Luisetto, G

    2011-01-01

    Calcium is essential for many metabolic process, including nerve function, muscle contraction, and blood clotting. The metabolic pathways that contribute to maintain serum calcium levels are bone remodeling processes, intestinal absorption and secretion, and renal handling, but hypercalcemia occurs when at least 2 of these 3 metabolic pathways are altered. Calcium metabolism mainly depends on the activity of parathyroid hormone (PTH). Its secretion is strictly controlled by the ionized serum calcium levels through a negative feed-back, which is achieved by the activation of calcium-sensing receptors (CaSRs) mainly expressed on the surface of the parathyroid cells. The PTH receptor in bone and kidney is now referred as PTHR1. The balance of PTH, calcitonin, and vitamin D has long been considered the main regulator of calcium metabolism, but the function of other actors, such as fibroblast growth factor-23 (FGF-23), Klotho, and TPRV5 should be considered. Primary hyperparathyroidism and malignancy are the most common causes of hypercalcemia, accounting for more than 90% of cases. Uncontrolled hypercalcemia may cause renal impairment, both temporary (alteration of renal tubular function) and progressive (relapsing nephrolithiasis), leading to a progressive loss of renal function, as well as severe bone diseases, and heart damages. Advances in the understanding of all actors of calcium homeostasis will be crucial, having several practical consequences in the treatment and prevention of hypercalcemia. This would allow to move from a support therapy, sometimes ineffective, to a specific and addressed therapy, especially in patients with chronic hypercalcemic conditions unsuitable for surgery.

  8. Calcium and Calcium Supplements: Achieving the Right Balance

    Science.gov (United States)

    ... Duyff RL. American Dietetic Association Complete Food and Nutrition Guide. 4th ed. Hoboken, N.J.: John Wiley & Sons; 2012:140. Rosen HN. Calcium and vitamin D supplementation in osteoporosis. http://www.uptodate.com/home/index. ...

  9. Calcium carbonate and calcium sulfate in Martian meteorite EETA79001

    Science.gov (United States)

    Gooding, J. L.; Wentworth, S. J.

    1987-01-01

    Chips of glassy Lithology C of EETA79001 were studied by scanning electron microscopy and energy dispersive X-ray spectroscopy to determine the mineralogy and petrogenesis of the glass that was shown by others to contain trapped Mars-like gases. Calcium carbonite was identified as massive to acicular crystals for which Ca, C, and O were the major elements. Calcium sulfate was identified as prismatic-acicular crystals with Ca and S as the major elements.

  10. NADPH oxidase in the renal microvasculature is a primary target for blood pressure-lowering effects by inorganic nitrate and nitrite.

    Science.gov (United States)

    Gao, Xiang; Yang, Ting; Liu, Ming; Peleli, Maria; Zollbrecht, Christa; Weitzberg, Eddie; Lundberg, Jon O; Persson, A Erik G; Carlström, Mattias

    2015-01-01

    Renal oxidative stress and nitric oxide (NO) deficiency are key events in hypertension. Stimulation of a nitrate-nitrite-NO pathway with dietary nitrate reduces blood pressure, but the mechanisms or target organ are not clear. We investigated the hypothesis that inorganic nitrate and nitrite attenuate reactivity of renal microcirculation and blood pressure responses to angiotensin II (ANG II) by modulating nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity and NO bioavailability. Nitrite in the physiological range (10(-7)-10(-5) mol/L) dilated isolated perfused renal afferent arterioles, which were associated with increased NO. Contractions to ANG II (34%) and simultaneous NO synthase inhibition (56%) were attenuated by nitrite (18% and 26%). In a model of oxidative stress (superoxide dismutase-1 knockouts), abnormal ANG II-mediated arteriolar contractions (90%) were normalized by nitrite (44%). Mechanistically, effects of nitrite were abolished by NO scavenger and xanthine oxidase inhibitor, but only partially attenuated by inhibiting soluble guanylyl cyclase. Inhibition of NADPH oxidase with apocynin attenuated ANG II-induced contractility (35%) similar to that of nitrite. In the presence of nitrite, no further effect of apocynin was observed, suggesting NADPH oxidase as a possible target. In preglomerular vascular smooth muscle cells and kidney cortex, nitrite reduced both basal and ANG II-induced NADPH oxidase activity. These effects of nitrite were also abolished by xanthine oxidase inhibition. Moreover, supplementation with dietary nitrate (10(-2) mol/L) reduced renal NADPH oxidase activity and attenuated ANG II-mediated arteriolar contractions and hypertension (99±2-146±2 mm Hg) compared with placebo (100±3-168±3 mm Hg). In conclusion, these novel findings position NADPH oxidase in the renal microvasculature as a prime target for blood pressure-lowering effects of inorganic nitrate and nitrite. © 2014 American Heart Association, Inc.

  11. New Mechanism on Synergistic Effect of Nitrite and Triethanolamine Addition on the Corrosion of Ductile Cast Iron

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    K. T. Kim

    2016-01-01

    Full Text Available In general, we compared the different inhibition mechanisms of organic inhibitor with that of anodic inhibitor. When triethanolamine or nitrite was added separately to tap water for inhibiting the corrosion of ductile cast iron, large amounts of inhibitor were needed. This is because the corrosion inhibitors had to overcome the galvanic corrosion that occurs between graphite and matrix. In this work, we investigated the corrosion of ductile cast iron in tap water with/without inhibitors. The corrosion rate was measured using chemical immersion test and electrochemical methods, including anodic polarization test. The inhibited surface was analyzed using EPMA and XPS. Test solutions were analyzed by performing FT-IR measurement. When triethanolamine and nitrite coexisted in tap water, synergistic effect built up, and the inhibition effect was ca. 30 times more effective than witnessed with single addition. This work focused on the synergistic effect brought about by nitrite and triethanolamine and its novel mechanism was also proposed.

  12. Nitrite residue and malonaldehyde reduction in dendeng--Indonesian dried meat--influenced by spices, curing methods and precooking preparation.

    Science.gov (United States)

    Suryati, T; Astawan, M; Lioe, H N; Wresdiyati, T; Usmiati, S

    2014-03-01

    This research was conducted to reduce nitrite residue and malonaldehyde (MDA) content of dendeng through modifying the formulation of spices, curing technique and precooking preparation. The result showed that spiced fried dendeng was likely to contain high total phenolics and antioxidant activity. Wet cured dendeng combined with spices containing 2.0% coriander and 10.0% garlic and preparation by soaking before frying was effective to produce dendeng that had no detected nitrite residue and low MDA. In conclusion, the spice formulas used in this study could reduce nitrite residue and MDA level of dendeng, and the treatment prior to frying, by soaking the dendeng briefly in water, lowered MDA of non-spiced dendeng, but no effect of soaking was observed in spiced samples due to the very low MDA found in the samples. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Nitrite and Nitrous Oxide Reductase Regulation by Nitrogen Oxides in Rhodobacter sphaeroides f. sp. denitrificans IL106

    Science.gov (United States)

    Sabaty, Monique; Schwintner, Carole; Cahors, Sandrine; Richaud, Pierre; Verméglio, Andre

    1999-01-01

    We have cloned the nap locus encoding the periplasmic nitrate reductase in Rhodobacter sphaeroides f. sp. denitrificans IL106. A mutant with this enzyme deleted is unable to grow under denitrifying conditions. Biochemical analysis of this mutant shows that in contrast to the wild-type strain, the level of synthesis of the nitrite and N2O reductases is not increased by the addition of nitrate. Growth under denitrifying conditions and induction of N oxide reductase synthesis are both restored by the presence of a plasmid containing the genes encoding the nitrate reductase. This demonstrates that R. sphaeroides f. sp. denitrificans IL106 does not possess an efficient membrane-bound nitrate reductase and that nitrate is not the direct inducer for the nitrite and N2O reductases in this species. In contrast, we show that nitrite induces the synthesis of the nitrate reductase. PMID:10498715

  14. On two site-specific nitrite-sensing nanocomposites having a core-shell structure: Construction, characterization and sensing performance.

    Science.gov (United States)

    Kadeerhazi, Muhetaer; Ali, Azam; Bekhit, Alaa El-Din

    2017-01-15

    This paper reported two site-specific nitrite-sensing nanocomposite samples having a core-shell structure, where Fe3O4 nanoparticles were used as core, two rhodamine derivatives served as chemosensor and MCM-41 was applied as supporting host, respectively. These composite samples and their structure were analyzed and confirmed SEM/TEM, XRD, N2 adsorption/desorption, magnetic feature, IR and thermogravimetric analysis. Their nitrite sensing performance was discussed based on emission quenching, with limit of detection as low as 1.2μM. Detailed analysis suggested that these composite samples followed a static sensing mechanism based on an additive reaction between NO+ and chemosensors. After being quenched by nitrite, these samples could be recovered by sulphamic acid. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Mapping of the binding site on pseudoazurin in the transient 152 kDa complex with nitrite reductase.

    Science.gov (United States)

    Impagliazzo, Antonietta; Ubbink, Marcellus

    2004-05-12

    Nitrite reductase (NiR) catalyzes the reduction of nitrite to nitrite oxide as a part of the denitrification process. In Alcaligenes faecalis S-6, the copper protein pseudoazurin acts as electron donor to NiR. The binding surface of pseudoazurin involved in the formation of the 152 kDa complex with NiR has been determined by NMR using cross saturation from NiR to perdeuterated pseudoazurin. Due to the transient nature of the complex, saturation effects can be observed on the resonances of the unbound protein. The binding site comprises the hydrophobic area surrounding the exposed copper ligand His81, suggesting that this residue is important for efficient electron transfer.

  16. Nitrogen removal from pharmaceutical manufacturing wastewater via nitrite and the process optimization with on-line control.

    Science.gov (United States)

    Li, Y Z; Peng, C Y; Peng, Y Z; Wang, P

    2004-01-01

    In this study, laboratory scale experiments were conducted to investigate the nitrogen removal from pharmaceutical manufacturing wastewater. The results indicate that by selective inhibition of free ammonia on oxidizers, nitrogen removal can be achieved by nitritation and denitritation process. The nitrite ratio was above 98% in the aerobic stage and the nitrogen removal efficiency was about 99%. The complete ammonia removal corresponded exactly to the "Ammonia Valley" in the pH versus time graphic and the anoxic reaction was completed when the "Nitrite Knee" appeared in the ORP versus time graphic. Optimization of the SBR cycle by step-feed and on-line control with pH and ORP strategy allowed the carbon and energy saving. The easy operation and the low cost make the SBR system an interesting option for the biological nitrogen removal from the pharmaceutical manufacturing wastewater.

  17. Hydrotris(triazolyl)borate complexes as functional models for Cu nitrite reductase: the electronic influence of distal nitrogens.

    Science.gov (United States)

    Kumar, Mukesh; Dixon, Natalie A; Merkle, Anna C; Zeller, Matthias; Lehnert, Nicolai; Papish, Elizabeth T

    2012-07-02

    Hydrotris(triazolyl)borate (Ttz) ligands form CuNO(x) (x = 2, 3) complexes for structural and functional models of copper nitrite reductase. These complexes have distinct properties relative to complexes of hydrotris(pyrazolyl)borate (Tp) and neutral tridentate N-donor ligands. The electron paramagnetic resonance spectra of five-coordinate copper complexes show rare nitrogen superhyperfine couplings with the Ttz ligand, indicating strong σ donation. The copper(I) nitrite complex [PPN](+)[(Ttz(tBu,Me))Cu(I)NO(2)](-) has been synthesized and characterized and allows for the stoichiometric reduction of NO(2)(-) to NO with H(+) addition. Anionic Cu(I) nitrite complexes are unusual and are stabilized here for the first time because Ttz is a good π acceptor.

  18. A novel sensor based on Fe3O4 nanoparticles–multiwalled carbon nanotubes composite film for determination of nitrite

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    Jianying Qu

    2015-03-01

    Full Text Available A novel nitrite sensor was constructed via electropolymerization of l-cysteine on the multiwalled carbon nanotubes and then immobilization of cationic poly(diallyldimethylammonium chloride coated Fe3O4 nanoparticles through electrostatic interaction at glassy carbon matrix. Under the optimized conditions, the obtained sensor exhibited good electrocatalytic activity for the oxidation of nitrite, and the peak current of nitrite increased linearly with its concentration from 7.49 × 10−6 to 3.33 × 10−3 mol/L (R = 0.9998 with the detection limit of 8.46 × 10−7 mol/L (S/N = 3. Moreover, the sensor exhibited good sensitivity, stability and repeatability with potential applications.

  19. Antitumor, Antioxidant, and Nitrite Scavenging Effects of Chinese Water Chestnut (Eleocharis dulcis) Peel Flavonoids.

    Science.gov (United States)

    Zhan, Ge; Pan, Leiqing; Tu, Kang; Jiao, Shunshan

    2016-10-01

    The preparation, quantification, and characterization of flavonoid compounds from Chinese water chestnut peel (CWCP) flavonoid extract and ethyl acetate fraction (EF), n-butanol fraction, and water fraction were studied. Among these, EF showed the maximum free radical levels (IC50 values of 0.36, 0.40, and 0.37 mg/mL for DPPH•, ABTS•+ , and •OH, respectively), nitrite scavenging effects (IC50 = 1.89 mg/mL), and A549 cell inhibitory activities (IC50 = 776.12 μg/mL) with the highest value of total flavonoid content (TFC, 421.32 mg/g). Moreover, the contents of 8 flavonoids in this fraction were quantified using high-performance liquid chromatography, and fisetin, diosmetin, luteolin, and tectorigenin were the 4 major flavonoids with levels of 31.66, 29.91, 13.69, and 12.41 mg/g, respectively. Luteolin produced a greater inhibition of human lung cancer A549 cells (IC50 = 59.60 μg/mL) than did fisetin, diosmetin, and tectorigenin. Flow cytometry revealed that the cellular mechanisms of luteolin inhibition of A549 cells were achieved via the induction of cell proliferation arrest at G1 phase and apoptosis/necrosis. Our findings suggest that flavonoids are closely associated with antitumor, antioxidant, and nitrite scavenging effects of CWCP. © 2016 Institute of Food Technologists®.

  20. Antioxidant and nitrite-scavenging capacities of phenolic compounds from sugarcane (Saccharum officinarum L.) tops.

    Science.gov (United States)

    Sun, Jian; He, Xue-Mei; Zhao, Mou-Ming; Li, Li; Li, Chang-Bao; Dong, Yi

    2014-08-26

    Sugarcane tops were extracted with 50% ethanol and fractionated by petroleum ether, ethyl acetate (EtOAc), and n-butyl alcohol successively. Eight phenolic compounds in EtOAc extracts were purified through silica gel and Sephadex LH-20 column chromatographies, and then identified by nuclear magnetic resonance and electrospray ionization mass spectra. The results showed that eight phenolic compounds from EtOAc extracts were identified as caffeic acid, cis-p-hydroxycinnamic acid, quercetin, apigenin, albanin A, australone A, moracin M, and 5'-geranyl-5,7,2',4'-tetrahydroxyflavone. The antioxidant and nitrite-scavenging capacities of different solvent extracts correlated positively with their total phenolic (TP) contents. Amongst various extracts, EtOAc extracts possessed the highest TP content and presented the strongest oxygen radical absorbance capacity (ORAC), 1,1'-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging capacity, 2,2'-azobis-3-ethylbenthiaazoline-6-sulfonic acid (ABTS) radical-scavenging capacity, ferric reducing antioxidant power (FRAP) and nitrite-scavenging capacity. Thus, sugarcane tops could be promoted as a source of natural antioxidant.