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Sample records for calcium nitrite

  1. Inhibition of nitrite-induced toxicity in channel catfish by calcium chloride and sodium chloride

    Science.gov (United States)

    Tommasso J.R., Wright, M. I.; Simco, B.A.; Davis, K.B.

    1980-01-01

    Environmental chloride has been shown to inhibit methemoglobin formation in fish, thereby offering a protective effect against nitrite toxicity. Channel catfish (Ictalurus punctatus) were simultaneously exposed to various environmental nitrite and chloride levels (as either CaCl2 or NaCl) in dechlorinated tap water (40 mg/L total hardness, 47 mg/L alkalinity, 4 mg/L chloride, pH = 6.9-7.1, and temperature 21-24°C). Methemoglobin levels in fish simultaneously exposed to 2.5 mg/L nitrite and up to 30 mg/L chloride as either CaCl2 or NaCl were similar but significantly lower than in unprotected fish. Exposure to 10 mg/L nitrite and 60 mg/L chloride resulted in methemoglobin levels similar to those of the controls; most unprotected fish died. Fish exposed to 10 mg/L nitrite had significantly lower methemoglobin levels when protected with 15.0 mg/L chloride as CaCl2 than with NaCl. Fish exposed to nitrite in the presence of 60 mg/L chloride (as either CaCl2 or NaCl) had similar 24-h LC50 values that were significantly elevated above those obtained in the absence of chloride. Calcium had little effect on tolerance to nitrite toxicity in channel catfish in contrast to its large effect reported in steelhead trout (Salmo gairdneri).

  2. Calcium-independent NO-synthase activity and nitrites/nitrates production in transient focal cerebral ischaemia in mice

    OpenAIRE

    Grandati, M; Verrecchia, C; Revaud, M L; Allix, M.; Boulu, R. G.; Plotkine, M.

    1997-01-01

    The temporal changes in constitutive NO-synthase (cNOS) and in calcium-independent NO-synthase activities were studied in mice subjected to 2 h of transient focal cerebral ischaemia. The changes in brain nitrites/nitrates (NOx) content were also studied.NOS activities were measured by the conversion of L-[14C]-arginine to L-[14C]-citrulline. Brain NOx contents were investigated by the Griess colourimetric method.cNOS activity in the infarcted cortical area was significantly reduced after 6 h ...

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

    International Nuclear Information System (INIS)

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

  4. 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.

  5. 21 CFR 181.34 - Sodium nitrite and potassium nitrite.

    Science.gov (United States)

    2010-04-01

    ... 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 nitrite are subject to prior sanctions issued by the U.S. Department of Agriculture for use as...

  6. 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

    Energy Technology Data Exchange (ETDEWEB)

    Hovind, Haavard

    1997-09-22

    The work described in this report was a part of an international cooperative programme for assessment and monitoring of acidification of rivers and lakes. Two sample sets were prepared for intercomparison, one for determination of the major ions, the other for determination of aluminium fractions and unspecified organic matter. The samples were sent to 50 laboratories and 47 laboratories from 22 countries submitted results. Good agreement was found for chloride, sulfate, calcium, magnesium, sodium and the unspecific organic compounds, dissolved organic carbon and chemical oxygen demand, more than 80% being evaluated as acceptable for these analytic variables. The results for nitrate + nitrite and aluminium species did not agree well, probably because different methods were used to determine the aluminium species. On the whole, 78% of the results were within the general target accuracy of plus or minus 20%. Laboratories with results outside this accuracy should improve their methods if they want to analyse low-concentration samples. To improve the compatibility of the analytical results for aluminium fractions, it seems necessary to normalize the analytical methods and determination techniques used for these determinations. A total error of plus minus 0.2 pH units seems to be a reasonable assessment of the accuracy for pH measurements when weakly acid or neutral water samples not in CO{sub 2} equilibrium are analyzed. 7 refs., 1 fig., 34 tabs.

  7. Oxygen Regulates Tissue Nitrite Metabolism

    OpenAIRE

    Curtis, Erin; Hsu, Lewis L.; Noguchi, Audrey C.; Geary, Lisa; Shiva, Sruti

    2012-01-01

    Aims: Once dismissed as an inert byproduct of nitric oxide (NO) auto-oxidation, nitrite (NO2-) is now accepted as an endocrine reservoir of NO that elicits biological responses in major organs. While it is known that tissue nitrite is derived from NO oxidation and the diet, little is known about how nitrite is metabolized by tissue, particularly at intermediate oxygen tensions. We investigated the rates and mechanisms of tissue nitrite metabolism over a range of oxygen concentrations. Results...

  8. 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., Jr.

    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.

  9. 21 CFR 573.700 - Sodium nitrite.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sodium nitrite. 573.700 Section 573.700 Food and... Listing § 573.700 Sodium nitrite. Sodium nitrite may be safely used in canned pet food containing meat and... byproducts so that the level of sodium nitrite does not exceed 20 parts per million. (b) To assure safe...

  10. 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.

  11. Allylic Nitro Compounds as Nitrite Donors

    OpenAIRE

    Chakrapani, Harinath; Gorczynski, Michael J.; King, S Bruce

    2006-01-01

    Allylic nitro compounds were synthesized and evaluated as organic sources of nitrite and nitric oxide. Unactivated allylic nitro compounds do not spontaneously release nitrite and nucleophile promoted nitrite release is slow. However, 2-(nitromethyl)-cyclohex-1-ene-3-one spontaneously dissociates in buffer (pH = 7.4) to release nitrite with a kobs = 1.6 × 10−5 s−1. In the presence of L-cysteine, this compound rapidly yields nitrite and reacts with hemoglobin similarly to sodium nitrite. Struc...

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

    OpenAIRE

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

    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. Fruiting bodies of the mushroom Boletus edulis were capable of inhibiting nitrite production during pickle fermentation. A 90-kDa nitrite reductase (NiR), demonstrating peptide sequence homology to fungal nitrite reductase, was isolated from B. edulis fruiting bodies. The optimum...

  13. 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...... nitrite levels for variable time periods, and changes in blood nitrosylhemoglobin (HbNO), methemoglobin (metHb), oxygenated hemoglobin (oxyHb) and deoxygenated hemoglobin (deoxyHb) were evaluated by spectral deconvolution. Blood HbNO (a biomarker of internal NO production) was low in controls, increased...... to a stable level around 3.7% of total Hb in fish exposed to 0.6 mmol l-1 nitrite, and to 12.1% (at day 2) in fish exposed to 2 mmol l-1 nitrite. The very high HbNO levels testify to an extensive conversion of nitrite to NO. With deoxyHb-mediated reduction of nitrite being a major NO...

  14. ADVANCED TECHNOLOGY WASTEWATER TREATMENT OF NITRITE IONS

    OpenAIRE

    E. G. Morozov; V.M. Nikol`skii; T.V. Saprunova; Yakovlev, A. A.

    2012-01-01

    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 t...

  15. Hypoxia tolerance, nitric oxide, and nitrite

    DEFF Research Database (Denmark)

    Fago, Angela; Jensen, Frank Bo

    2015-01-01

    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....

  16. 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..

  17. Nitrates and nitrites intoxications’ management

    OpenAIRE

    Alexandra Trif

    2007-01-01

    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 fertilizati...

  18. 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... Systems § 862.1510 Nitrite (nonquantitative) test system. (a) Identification. A nitrite (nonquantitative) test system is a device intended to identify nitrite in urine. Nitrite identification is used in...

  19. Nitrite, a Hidden Foe in Foods:Evaluation of Nitrite in Toxicological Perspective

    OpenAIRE

    Erkekoğlu, Pınar; Baydar, Terken

    2010-01-01

    ABSTRACTNitrites and nitrates possess a unique position in human toxicology. They are both ubiquitous in the environment and can be formed from nitrogenous compounds. Water, vegetables and meat are important sources of nitrite exposure. Nitrites have several detrimental effects on health. The primary health concern regarding nitrate and nitrite exposure is the formation of methemoglobinemia. Baby food and infant formulas can be important sources of nitrite and infants younger than six months ...

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

    Science.gov (United States)

    Deeb, Barbara S.; Sloan, Kenneth W.

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

  1. Radiation preservation of low nitrite bacon

    International Nuclear Information System (INIS)

    Sodium nitrite, a key ingredient of the mix used to cure bacon and other meats, promotes and fixes bacon's characteristic pink color, inhibits lipid peroxidation and prevents growth of micro-organisms, particularly Clostridium botulinum spores. Unfortunately, nitrite leads to the formation of carcinogenic nitrosamines in bacon. This has led to a search for alternatives to the use of nitrite. Irradiation with reduced level of nitrite is a promising alternative. Radurization of bacon containing 20 to 40 mg/kg of nitrite in evacuated packages, irradiated and stored at 40C, 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 -200 or lower in evacuated packages, results in a product that is shelf stable at room temperature for months to years. It has organoleptic qualities comparable to commercial bacon in terms of color, flavor, odor and texture. Irradiation also reduces the nitrite and preformed nitrosamines present in bacon. Various aspects of preservation of bacon are reviewed in this report with emphasis on radiation processing. (author)

  2. Oxygen isotopes in nitrite: Analysis, calibration, and equilibration

    Science.gov (United States)

    Casciotti, K.L.; Böhlke, J.K.; McIlvin, M.R.; Mroczkowski, S.J.; Hannon, J.E.

    2007-01-01

    Nitrite is a central intermediate in the nitrogen cycle and can persist in significant concentrations in ocean waters, sediment pore waters, and terrestrial groundwaters. To fully interpret the effect of microbial processes on nitrate (NO3-), nitrite (NO2-), and nitrous oxide (N2O) cycling in these systems, the nitrite pool must be accessible to isotopic analysis. Furthermore, because nitrite interferes with most methods of nitrate isotopic analysis, accurate isotopic analysis of nitrite is essential for correct measurement of nitrate isotopes in a sample that contains nitrite. In this study, nitrite salts with varying oxygen isotopic compositions were prepared and calibrated and then used to test the denitrifier method for nitrite oxygen isotopic analysis. The oxygen isotopic fractionation during nitrite reduction to N2O by Pseudomonas aureofaciens was lower than for nitrate conversion to N2O, while oxygen isotopic exchange between nitrite and water during the reaction was similar. These results enable the extension of the denitrifier method to oxygen isotopic analysis of nitrite (in the absence of nitrate) and correction of nitrate isotopes for the presence of nitrite in "mixed" samples. We tested storage conditions for seawater and freshwater samples that contain nitrite and provide recommendations for accurate oxygen isotopic analysis of nitrite by any method. Finally, we report preliminary results on the equilibrium isotope effect between nitrite and water, which can play an important role in determining the oxygen isotopic value of nitrite where equilibration with water is significant. ?? 2007 American Chemical Society.

  3. The role of nitrite in nitric oxide homeostasis

    DEFF Research Database (Denmark)

    Jensen, Frank Bo

    2009-01-01

    Nitrite is endogenously produced as an oxidative metabolite of nitric oxide, but it also functions as a NO donor that can be activated by a number of cellular proteins under hypoxic conditions. This article discusses the physiological role of nitrite and nitrite-derived NO in blood flow regulation...... and cytoprotection from a comparative viewpoint, with focus on mammals and fish. Constitutive nitric oxide synthase activity results in similar plasma nitrite levels in mammals and fish, but nitrite can also be taken up across the gills in freshwater fish, which has implications for nitrite/NO levels...... and nitrite utilization in hypoxia. The nitrite reductase activity of deoxyhemoglobin is a major mechanism of NO generation from nitrite and may be involved in hypoxic vasodilation. Nitrite is readily transported across the erythrocyte membrane, and the transport is enhanced at low O2 saturation in...

  4. Calcium - urine

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003603.htm Calcium - urine To use the sharing features on this ... enable JavaScript. This test measures the amount of calcium in urine. All cells need calcium in order ...

  5. 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 ...

  6. Inhibition Of Washed Sludge With Sodium Nitrite

    Energy Technology Data Exchange (ETDEWEB)

    Congdon, J. W.; Lozier, J. S.

    2012-09-25

    This report describes the results of electrochemical tests used to determine the relationship between the concentration of the aggressive anions in washed sludge and the minimum effective inhibitor concentration. Sodium nitrate was added as the inhibitor because of its compatibility with the DWPF process. A minimum of 0.05M nitrite is required to inhibit the washed sludge simulant solution used in this study. When the worst case compositions and safety margins are considered, it is expected that a minimum operating limit of nearly 0.1M nitrite will be specified. The validity of this limit is dependent on the accuracy of the concentrations and solubility splits previously reported. Sodium nitrite additions to obtain 0.1M nitrite concentrations in washed sludge will necessitate the additional washing of washed precipitate in order to decrease its sodium nitrite inhibitor requirements sufficiently to remain below the sodium limits in the feed to the DWPF. Nitrite will be the controlling anion in "fresh" washed sludge unless the soluble chloride concentration is about ten times higher than predicted by the solubility splits. Inhibition of "aged" washed sludge will not be a problem unless significant chloride dissolution occurs during storage. It will be very important tomonitor the composition of washed sludge during processing and storage.

  7. Calcium Oscillations

    OpenAIRE

    Dupont, Geneviève; Combettes, Laurent; Bird, Gary S.; Putney, James W.

    2011-01-01

    Calcium signaling results from a complex interplay between activation and inactivation of intracellular and extracellular calcium permeable channels. This complexity is obvious from the pattern of calcium signals observed with modest, physiological concentrations of calcium-mobilizing agonists, which typically present as sequential regenerative discharges of stored calcium, a process referred to as calcium oscillations. In this review, we discuss recent advances in understanding the underlyin...

  8. Sensing nitrite through a pseudoazurin-nitrite reductase electron transfer relay

    NARCIS (Netherlands)

    Astier, Y; Canters, GW; Davis, JJ; Hill, HAO; Verbeet, MP; Wijma, HJ

    2005-01-01

    Nitrite is converted to nitric oxide by haem or copper-containing enzymes in denitrifying bacteria during the process of denitrification. In designing an efficient biosensor, this enzymic turnover must be quantitatively assessed. The enzyme nitrite reductase from Alcaligenes faecalis contains a redo

  9. Nitrite Reductase Activity in Engineered Azurin Variants.

    Science.gov (United States)

    Berry, Steven M; Strange, Jacob N; Bladholm, Erika L; Khatiwada, Balabhadra; Hedstrom, Christine G; Sauer, Alexandra M

    2016-05-01

    Nitrite reductase (NiR) activity was examined in a series of dicopper P.a. azurin variants in which a surface binding copper site was added through site-directed mutagenesis. Four variants were synthesized with copper binding motifs inspired by the catalytic type 2 copper binding sites found in the native noncoupled dinuclear copper enzymes nitrite reductase and peptidylglycine α-hydroxylating monooxygenase. The four azurin variants, denoted Az-NiR, Az-NiR3His, Az-PHM, and Az-PHM3His, maintained the azurin electron transfer copper center, with the second designed copper site located over 13 Å away and consisting of mutations Asn10His,Gln14Asp,Asn16His-azurin, Asn10His,Gln14His,Asn16His-azurin, Gln8Met,Gln14His,Asn16His-azurin, and Gln8His,Gln14His,Asn16His-azurin, respectively. UV-visible absorption spectroscopy, EPR spectroscopy, and electrochemistry of the sites demonstrate copper binding as well as interaction with small exogenous ligands. The nitrite reduction activity of the variants was determined, including the catalytic Michaelis-Menten parameters. The variants showed activity (0.34-0.59 min(-1)) that was slower than that of native NiRs but comparable to that of other model systems. There were small variations in activity of the four variants that correlated with the number of histidines in the added copper site. Catalysis was found to be reversible, with nitrite produced from NO. Reactions starting with reduced azurin variants demonstrated that electrons from both copper centers were used to reduce nitrite, although steady-state catalysis required the T2 copper center and did not require the T1 center. Finally, experiments separating rates of enzyme reduction from rates of reoxidation by nitrite demonstrated that the reaction with nitrite was rate limiting during catalysis. PMID:27055058

  10. Nitrite disrupts multiple physiological functions in aquatic animals

    DEFF Research Database (Denmark)

    Jensen, Frank Bo

    2003-01-01

    Nitrite is a potential problem in aquatic environments. Freshwater fish actively take up nitrite across the gills, leading to high internal concentrations. Seawater fish are less susceptible but do take up nitrite across intestine and gills. Nitrite has multiple physiological effects. Its uptake is...... at the expense of chloride, leading to chloride depletion. Nitrite also activates efflux of potassium from skeletal muscle and erythrocytes, disturbing intracellular and extracellular K+ levels. Nitrite transfer across the erythrocytic membrane leads to oxidation of haemoglobin to methaemoglobin (met...... nitrite-induced vasodilation (possibly via nitric oxide generated from nitrite) that is countered by increased cardiac pumping to re-establish blood pressure. Nitrite can form and/or mimic nitric oxide and thereby interfere with processes regulated by this local hormone. Steroid hormone synthesis may be...

  11. Nitrite controls the release of nitric oxide in Pseudomonas aeruginosa cd1 nitrite reductase

    International Nuclear Information System (INIS)

    Nitrite reductase (cd1NIR) from Pseudomonas aeruginosa, which catalyses the reduction of nitrite to nitric oxide (NO), contains a c-heme as the electron acceptor and a d1-heme where catalysis occurs. Reduction involves binding of nitrite to the reduced d1-heme, followed by dehydration to yield NO; release of NO and re-reduction of the enzyme close the cycle. Since NO is a powerful inhibitor of ferrous hemeproteins, enzymatic turnover demands the release of NO. We recently discovered that NO dissociation from the ferrous d1-heme is fast, showing that cd1NIR behaves differently from other hemeproteins. Here we demonstrate for the first time that the physiological substrate nitrite displaces NO from the ferrous enzyme, which enters a new catalytic cycle; this reaction depends on the conserved His369 whose role in substrate stabilization is crucial for catalysis. Thus we suggest that also in vivo the activity of cd1NIR is controlled by nitrite

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

    Directory of Open Access Journals (Sweden)

    Sirada Srihirun

    Full Text Available BACKGROUND: 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. METHODOLOGY/FINDING: 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. CONCLUSION: 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. In Vitro Killing of Mycobacterium ulcerans by Acidified Nitrite

    Science.gov (United States)

    Phillips, R.; Kuijper, S.; Benjamin, N.; Wansbrough-Jones, M.; Wilks, M.; Kolk, A. H. J.

    2004-01-01

    Mycobacterium ulcerans, which causes Buruli ulcer, was exposed to acidified nitrite or to acid alone for 10 or 20 min. Killing was rapid, and viable counts were reduced below detectable limits within 10 min of exposure to 40 mM acidified nitrite. M. ulcerans is highly susceptible to acidified nitrite in vitro. PMID:15273132

  15. 9 CFR 319.2 - Products and nitrates and nitrites.

    Science.gov (United States)

    2010-01-01

    ... standard in this part and to which nitrate or nitrite is permitted or required to be added, may be prepared without nitrate or nitrite and labeled with such standard name when immediately preceded with the term... to such product as commonly prepared with nitrate and nitrite: And provided further, That...

  16. Methaemoglobinaemia after ingestion of amyl nitrite.

    OpenAIRE

    Forsyth, R. J.; Moulden, A

    1991-01-01

    We report a case of methaemoglobinaemia in a 2 year old girl after ingestion of an 'aphrodisiac' containing nitrite. The availability of these products, their poor labelling, and their intended presence in domestic bedrooms all serve to increase the hazard they pose to young children.

  17. Determination of Nitric Oxide-Derived Nitrite and Nitrate in Biological Samples by HPLC Coupled to Nitrite Oxidation

    OpenAIRE

    Wu, Anguo; Duan, Tingting; Tang, Dan; Xu, Youhua; Feng, Liang; Zheng, Zhaoguang; Zhu, Jiaxiao; Wang, Rushang; Zhu, Quan

    2013-01-01

    Nitrite and nitrate are main stable products of nitric oxide, a pivotal cellular signaling molecule, in biological fluids. Therefore, accurate measurement of the two ions is profoundly important. Nitrite is difficult to be determined for a larger number of interferences and unstable in the presence of oxygen. In this paper, a simple, cost-effective and accurate HPLC method for the determination of nitrite and nitrate was developed. On the basis of the reaction that nitrite is oxidized rapidly...

  18. Severe Methemoglobinemia due to Sodium Nitrite Poisoning.

    Science.gov (United States)

    Katabami, Kenichi; Hayakawa, Mineji; Gando, Satoshi

    2016-01-01

    Case. We report a case of severe methemoglobinemia due to sodium nitrite poisoning. A 28-year-old man was brought to our emergency department because of transient loss of consciousness and cyanosis. He was immediately intubated and ventilated with 100% oxygen. A blood test revealed a methemoglobin level of 92.5%. Outcome. We treated the patient with gastric lavage, activated charcoal, and methylene blue (2 mg/kg) administered intravenously. Soon after receiving methylene blue, his cyanosis resolved and the methemoglobin level began to decrease. After relocation to the intensive care unit, his consciousness improved and he could recall ingesting approximately 15 g sodium nitrite about 1 hour before he was brought to our hospital. The patient was discharged on day 7 without neurologic impairment. Conclusion. Severe methemoglobinemia may be fatal. Therefore, accurate diagnosis of methemoglobinemia is very important so that treatment can be started as soon as possible. PMID:27563472

  19. 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

  20. 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

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

    International Nuclear Information System (INIS)

    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

  2. Determination of Nitrite in Meat Products using a Metalloporphyrin Based Nitrite-Selective Membrane Electrode

    Directory of Open Access Journals (Sweden)

    Dana VLASCICI

    2006-07-01

    Full Text Available The potentiometric response characteristics of a nitrite-selective electrode based on Co (III tetraphenylporphyrins (TPP in o-nitrophenyloctylether plasticized polyvinyl chloride membranes are compared. To establish the optimum composition of the membrane, different molar percents of cationic derivative (0-100 mol% relative to ionophore were used. The influence of different plasticizers: o-nitrophenyloctylether, dioctylphtalate and tricresilphosphate on potentiometric answer were studied. Electrodes formulated with membranes containing 1 wt% ClCoTPP, 66 wt% o-NPOE, 33 wt% PVC (plasticizer:PVC = 2:1 and the lipophilic cationic derivative (10 mol% are shown to exhibit high selectivity for nitrite over many anions, except the lipophilic anions perchlorate and thiocyanate. The electrodes based on Co (III porphyrins were used for the potentiometric determination of nitrites in meat products. The results were compared with a colorimetric method used as the reference method. There was a good agreement between the potentiometric and colorimetric procedures.

  3. Biomass Industrial Effluent Effect on Carbohydrates, Aminoacids, Nitrite and Nitrite Enzyme Activities of Arachis hypogaea L

    Institute of Scientific and Technical Information of China (English)

    PC Nagajyoti; N Dinakarc; S Suresh; Y Udaykiran; C Suresh; T N V K V Prasad; T Damodharam

    2009-01-01

    The objectives of the present investigations are to see the effects of biomass power plant effluent on the carbohydrates, aminoacids, nitrite and nitrite enzyme activitiesand proline of Arachis hypogaea L. vat TCGS 320 under controlled pot culture methods. Plants were cultivated with 25, 50, 75 and 100% of the effluent and a control without the effluent. The treatment of the crop with 25% of the effluent has shown stimulatory effect on all the biochemical parameters studied. Carbohydrates, starch, aminoacids, protein, nitrate and nitrite reductase enzymatic activities have increased in 10, 15, 20 DAS (days after sowing). In 25 and 30 DAS all biochemical parameters have decreased, due to environmental factors (rainfall, temperature, humidity, etc.). The present investigation clearly indicated that the biomass power plant effluent has stimulatory effect on all the biochemical contents at lower concentration, and at higher concentration they have deleterious effects.

  4. 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...... concentration, soluble guanylate cyclase (the target for vasoactive nitric oxide) and known nitrite-reductase activities, including that of hemoglobin, xanthine oxidase, endothelial nitric oxide synthase and the bc1 complex of the mitochondria under hypoxia. We found that vasodilation followed overall first......-order dependency on nitrite concentration, at high and low oxygen levels, and that it was induced by nitrite concentrations comparable to those found in vivo, when using low oxygenation and norepinephrine levels. The nitrite vasoactivity during hypoxia was abolished upon inhibition of soluble guanylate cyclase and...

  5. NITRATE AND NITRITE CONCENTRATION IN VEGETABLES GRAWING AROUND ISFAHAN CITY

    OpenAIRE

    R.A JAFARI; A AZIZ ZADEH; A FARZAN

    2001-01-01

    Introduction: The improper and excess use of chemical fertilizers by the farmers special in "urea" form may cause the commulation of nitrates and nitrites in vegetables and fruits. This investigation has been done to determine the concentration of nitrates and nitrites in some vegetables growing around Isfahan. Methods: One hundred and thirteen random samples from 15 different kinds of green lest tuber vegetables were measured by Cadmium Column Procedure for nitrates and nitrites. R...

  6. The effect of nitrite inhibition on the anammox process.

    Science.gov (United States)

    Lotti, T; van der Star, W R L; Kleerebezem, R; Lubello, C; van Loosdrecht, M C M

    2012-05-15

    The negative effect of nitrite on anammox activity has been reported widely during the past decade. Although the adverse effect is clear, conflicting reports exist on the level at which it occurs and its reversible/irreversible nature. An in depth study on nitrite inhibition therefore was performed in which the influence of environmental factors was evaluated. Anammox activity was measured in anammox granules by continuously monitored standardized manometric batch tests extending the interpretation by evaluation of lag times, maximum conversion rates during the tests and substrates/product conversion ratios. The granules where obtained from a one-stage anammox reactor, the dominant anammox organisms belonged to the Brocadia type. The observed 50% activity inhibition for nitrite (IC(50)) was 0.4 g N L(-1). The activity recovered fully after removal of the nitrite. Conversion in fresh medium after exposure to up to 6 g NO(2)(-)-N L(-1) for 24 h showed less then 60% loss of activity. Presence of ammonium during nitrite (2 g N L(-1)) exposure resulted in a stronger loss of activity after nitrite exposure (50% and 30% in presence and absence of ammonium respectively). Presence of oxygen during nitrite incubation led to a maximum activity reduction of 32%. The recovery after exposure indicates that the adverse effect of nitrite is reversible and thus inhibitory rather than toxic in nature. Similarities between exposure at three different pH-values indicate that nitrite rather than nitrous acid is the actual inhibiting compound. PMID:22424965

  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...... anaerobically in vitro, their relative contribution to the hypoxic vasodilatory response has remained unsolved. Using a wire myograph, we have investigated how the nitrite-dependent vasodilation in rat aortic rings is controlled by oxygen tension, norepinephrine concentration, soluble guanylate cyclase (the...... 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...

  8. Differences in nitrite-oxidizing communities and kinetics in a brackish environment after enrichment at low and high nitrite concentrations.

    Science.gov (United States)

    Tangkitjawisut, Wipasanee; Limpiyakorn, Tawan; Powtongsook, Sorawit; Pornkulwat, Preeyaporn; Suwannasilp, Benjaporn Boonchayaanant

    2016-04-01

    Nitrite accumulation in shrimp ponds can pose serious adverse effects to shrimp production and the environment. This study aims to develop an effective process for the enrichment of ready-to-use nitrite-oxidizing bacteria (NOB) inocula that would be appropriate for nitrite removal in brackish shrimp ponds. To achieve this objective, the effects of nitrite concentrations on NOB communities and nitrite oxidation kinetics in a brackish environment were investigated. Moving-bed biofilm sequencing batch reactors and continuous moving-bed biofilm reactors were used for the enrichment of NOB at various nitrite concentrations, using sediment from brackish shrimp ponds as seed inoculum. The results from NOB population analysis with quantitative polymerase chain reaction (qPCR) show that only Nitrospira were detected in the sediment from the shrimp ponds. After the enrichment, both Nitrospira and Nitrobacter coexisted in the reactors controlling effluent nitrite at 0.1 and 0.5 mg-NO2(-)-N/L. On the other hand, in the reactors controlling effluent nitrite at 3, 20, and 100 mg-NO2(-)-N/L, Nitrobacter outcompeted Nitrospira in many orders of magnitude. The half saturation coefficients (Ks) for nitrite oxidation of the enrichments at low nitrite concentrations (0.1 and 0.5 mg-NO2(-)-N/L) were in the range of 0.71-0.98 mg-NO2(-)-N/L. In contrast, the K(s) values of NOB enriched at high nitrite concentrations (3, 20, and 100 mg-NO2(-)-N/L) were much higher (8.36-12.20 mg-NO2(-)-N/L). The results suggest that the selection of nitrite concentrations for the enrichment of NOB inocula can significantly influence NOB populations and kinetics, which could affect the effectiveness of their applications in brackish shrimp ponds. PMID:27090693

  9. A Nitrite Microsensor for Profiling Environmental Biofilms

    OpenAIRE

    D. de Beer; Schramm, A.; Santegoeds, C. M.; Kuhl, M.

    1997-01-01

    A highly selective liquid membrane nitrite microsensor based on the hydrophobic ion-carrier aquocyanocobalt(III)-hepta(2-phenylethyl)-cobrynate is described. The sensor has a tip diameter of 10 to 15 (mu)m. The response is log-linear in freshwater down to 1 (mu)M NO(inf2)(sup-) and in seawater to 10 (mu)M NO(inf2)(sup-). A method is described for preparation of relatively large polyvinyl chloride (PVC)-gelled liquid membrane microsensors with a tip diameter of 5 to 15 (mu)m, having a hydrophi...

  10. Origin, causes and effects of increased nitrite concentrations in aquatic environments

    NARCIS (Netherlands)

    Philips, S.; Laanbroek, H.J.; Verstraete, W.

    2002-01-01

    Literature frequently mentions increased nitrite concentrations along with its inhibitory effect towards bacteria and aquatic life. Nitrite accumulation has been studied for decades, and although numerous causal factors have already been commented on in literature, the mechanism of nitrite accumulat

  11. Calcium Carbonate

    Science.gov (United States)

    ... before being swallowed; do not swallow them whole. Drink a full glass of water after taking either the regular or chewable tablets or capsules. Some liquid forms of calcium carbonate must be shaken well before use.Do not ...

  12. 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<0.0001) or...

  13. Calcium Calculator

    Science.gov (United States)

    ... Latvia - Lebanon - Libya - Lithuania - Luxembourg - Macedonia, Republic of - Malaysia - Malta - Mexico - Moldova - Morocco - Netherlands - New Zealand - Nigeria - ... and Statistics Popular content Calcium content of common foods What is Osteoporosis? The Board Introduction to Bone ...

  14. The Impact of Nitrite on Aerobic Growth of Paracoccus denitrificans PD1222

    OpenAIRE

    Hartop, Katherine

    2014-01-01

    The effect of nitrite stress induced in Paracoccus denitrificans PD1222 was examined using additions of sodium nitrite to an aerobic bacterial culture. Nitrite generates a strong stress response in P. denitrificans, causing growth inhibition. This is dependent on both the concentration of nitrite present and the pH. The pH dependent effect of nitrite growth inhibition is likely a result of nitrite and free nitrous acid (FNA; pKa = 3.16) and subsequent reactive nitrogen oxides, ...

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

    NARCIS (Netherlands)

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

    2002-01-01

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

  16. Bidirectional catalysis by copper-containing nitrite reductase

    NARCIS (Netherlands)

    Wijma, HJ; Canters, GW; de Vries, S; Verbeet, MP

    2004-01-01

    The copper-containing nitrite reductase from Alcaligenes faecalis S-6 was found to catalyze the oxidation of nitric oxide to nitrite, the reverse of its physiological reaction. Thermodynamic and kinetic constants with the physiological electron donor pseudoazurin were determined for both directions

  17. 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...

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

    NARCIS (Netherlands)

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

    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.

  19. Spectrophotometric determination of nitrite using salbutamol sulfate as a reagent

    Energy Technology Data Exchange (ETDEWEB)

    Agrawal, Y.K.; Bhatt, P.N.

    1988-01-01

    A simple spectrophotometric method for the trace determination of nitrite (NO/sub 2//sup /minus//) is described. Nitrite is reacted with Salbutamol sulfate in acidic medium which gives a yellow color in alkaline medium (less than or equal to pH 7) and can be determined in the presence of several cations and anions. Beer's law is obeyed in the range of 1.8 to 27.6 ppm of nitrite with the molar absorptivity 1.8 /times/ 10/sup 3/ 1 /times/ mole /sup /minus/1/ /times/ cm/sup /minus/1/ at 410 nm. The proposed method can also be utilized for the determination of nitrate (NO/sub 3//sup /minus//) after its reduction to nitrite. The method has been applied for the determination of various samples containing traces of nitrite.

  20. Electrochemical processing of alkaline nitrate and nitrite wastes

    International Nuclear Information System (INIS)

    Processing of high-level waste at the Savannah River Plant (SRP) will produce, as a by-product, a low-level, alkaline salt solution containing approximately 17% sodium nitrate and sodium nitrite. This solution will be incorporated into a cement formulation, saltstone, and placed in an engineered landfill. Electrochemical methods have been investigated to decrease the nitrate and nitrite in this solution in order to lower the leaching of nitrate and nitrite from saltstone and to reduce the volume of saltstone. Laboratory experiments have demonstrated the technical feasibility of electrolytically reducing the nitrate and nitrite in a synthetic salt solution similar in composition to that expected to be produced at SRP. Greater than 99% of the sodium nitrate and sodium nitrite can be reduced, producing ammonia, nitrogen, oxygen, and sodium hydroxide. In addition, significant reductions in the volume of saltstone may be realized if the sodium hydroxide produced by electrolysis can be recycled

  1. Electrolytic denitrification of alkaline nitrate and nitrite solution

    International Nuclear Information System (INIS)

    Processing of high-level waste at the Savannah River Plant (SRP) will produce a low-level alkaline salt solution, containing approximately 17% sodium nitrate and sodium nitrite. This solution will be incorporated into a cement wasteform, saltstone, and placed in an engineered landfill. Laboratory experiments have demonstrated the technical feasibility of electrochemically reducing the nitrate and nitrite in a synthetic, nonradioactive salt solution similar in composition to that expected to be produced at SRP. Greater than ninety-five percent of the sodium nitrate and sodium nitrite can be reduced electrolytically, producing ammonia, nitrogen, oxygen, and sodium hydroxide. Reduction of the nitrate and nitrite will reduce the leaching of nitrate and nitrite from the saltstone monolith. In addition, significant reductions in the volume of saltstone may be realized if the sodium hydroxide produced by electrolysis can be recycled

  2. Electrochemical processing of alkaline nitrate and nitrite solutions

    International Nuclear Information System (INIS)

    Processing of high-level waste at the Savannah River Plant (SRP) will produce, as a by product, a low- level, alkaline salt solution containing approximately 17% sodium nitrate and sodium nitrite. This solution will be incorporated into a cement formulation, saltstone, and placed in an engineered landfill. Electrochemical methods have been investigated to decrease the nitrate and nitrite in this solution in order to lower the leaching of nitrate and nitrite from saltstone and to reduce the volume of saltstone. Laboratory experiments have demonstrated the technical feasibility of electrolytically reducing the nitrate and nitrite in a synthetic salt solution similar in composition to that expected to be produced at SRP. Greater than 99% of the sodium nitrate and sodium nitrite can be reduced, producing ammonia, nitrogen, oxygen, and sodium hydroxide. In addition, significant reductions in the volume of saltstone may be realized if the sodium hydroxide produced by electrolysis can be recycled

  3. 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; Machado, Roberto F

    2016-02-15

    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

  4. Investigating the inhibiting effect of sodium nitrite on equipment corrosion

    International Nuclear Information System (INIS)

    Sodium nitrite as a corrosion inhibitor is widely used for protecting equipment components made of carbon steel. It is well known that nitrite addition at several grams per liter level can efficiently reduce carbon steel corrosion even in sea water. However, nitrites are very hazardous for environment and concentrated inhibitor solutions are hard to dispose of. Therefore, it is important to experimentally determine the minimum nitrite concentrations capable of protecting structural materials from corrosion. There is also concern about highly probable releases of significant chloride amounts into the coolant water as a result of accidental heat transfer equipment failures. In light of this problem, the following research tasks have been set: determine the lower limit for nitrite concentration which can inhibit corrosion of steels with different surfaces conditions; measure the rate of a decrease in the nitrite concentration due to inhibition process with formation of γ-Fe2O3 and ammonia, and nitrite oxidation to nitrate by reaction with dissolved oxygen; assess the influence of chloride and nitrate concentration on the inhibition efficiency. The present paper describes results of corrosion tests on specimens of Russian grade CT3 and CT20 steels with different surface conditions in demineralized water with chloride impurities. Sodium nitrite concentrations for steel specimens with both polished surface and surface with corrosion pits were specified. The minimum sufficient concentration of the inhibitor to protect the heat transfer equipment against corrosion was determined. The experiments have measured the limiting concentrations of nitrate and chloride ions for sodium nitrite as an active inhibitor of corrosion. Based on the results obtained, new algorithms for calculation of optimum nitrite dosage have been developed. (author)

  5. 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

    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...

  6. 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

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

    DEFF Research Database (Denmark)

    Lackner, Susanne; Smets, Barth F.

    2012-01-01

    The effect of biokinetics on nitritation was investigated in two biofilm geometries, the Membrane Aerated Biofilm Reactor (MABR) and a conventional biofilm system. A 1D biofilm model was used and evaluated by global sensitivity analysis using the variance based Sobol method. The main focus was on...... the influence of key biokinetic parameters (maximum specific growth rates, oxygen and nitrogen affinity constants of AOB (ammonium oxidizing bacteria) and NOB (nitrite oxidizing bacteria)) and their ratios on nitritation efficiency in these geometries. This exhaustive simulation study revealed that...... nitritation strongly depends on the chosen kinetic parameters of AOB and NOB. The maximum specific growth rates (μmax,AOB and μmax,NOB) had the strongest impact on nitritation efficiency (NE). In comparison, the counter-diffusion geometry yielded more parameter combinations (27.5%) that resulted in high NE...

  8. Determination of Nitrite in Meat Products using a Metalloporphyrin Based Nitrite-Selective Membrane Electrode

    OpenAIRE

    Vlascici, Dana; Pica, Elena Maria; Eugenia Fagadar COSMA; Bizerea, Otilia; Cosma, Viorica

    2006-01-01

    The potentiometric response characteristics of a nitrite-selective electrode based on Co (III) tetraphenylporphyrins (TPP) in o-nitrophenyloctylether plasticized polyvinyl chloride membranes are compared. To establish the optimum composition of the membrane, different molar percents of cationic derivative (0-100 mol% relative to ionophore) were used. The influence of different plasticizers: o-nitrophenyloctylether, dioctylphtalate and tricresilphosphate on potentiometric answer were studied. ...

  9. Calcium pyrophosphate arthritis

    Science.gov (United States)

    Calcium pyrophosphate dihydrate deposition disease; CPPD disease; Acute CPPD arthritis; Pseudogout ... Calcium pyrophosphate arthritis is caused by the collection of salt called calcium pyrophosphate dihydrate (CPPD). The buildup ...

  10. NITRATE AND NITRITE CONCENTRATION IN VEGETABLES GRAWING AROUND ISFAHAN CITY

    Directory of Open Access Journals (Sweden)

    R.A JAFARI

    2001-06-01

    Full Text Available Introduction: The improper and excess use of chemical fertilizers by the farmers special in "urea" form may cause the commulation of nitrates and nitrites in vegetables and fruits. This investigation has been done to determine the concentration of nitrates and nitrites in some vegetables growing around Isfahan. Methods: One hundred and thirteen random samples from 15 different kinds of green lest tuber vegetables were measured by Cadmium Column Procedure for nitrates and nitrites. Results: The mean of the nitrates level in green leaf and tuber-vegetables was 287.9 and 76.3 mg/kg, respectively. These amounts were more higher than standard value (67 mg/kg in the basis of wet material, significantly. The mean of the nitrite level in green leaf and tuber vegetables were 1.7 and 1 mg/kg, repectively, which were more higher than standard value (zero mg/kg in the basis of wet matrial. The most high concentration of nitrites and nitrates was seen in commondill and leek, repectively. Discussion: Amounts of nitrites and nitrates in our analysed samples exceeded the perimissible limits. The comulation of nitrates in some of the vegetables depend on the application of chemical fertilizers, temprature and wether, but the nitrites in vegetables is unusual in normal condition and the unsuitable storage of them causes it"s expansion.

  11. Nitrite removal from marine aquaculture wastewater using electrochemical process

    International Nuclear Information System (INIS)

    The hazardous and toxic nature of some of the constituent such as nitrite in the aquaculture wastewater is of major concern. Present study focuses the removal of nitrite from the aquaculture wastewater prior to disposal. Effect of certain operational parameters such as electrode material, current density, initial pH, and electrode spacing on nitrite removal from aquaculture wastewater was elucidated. Better nitrite removal efficiency achieved when nickel used as compared to stainless steel, graphite and aluminum electrodes. Nitrite removal is positively related to the current density however, increase is up to 31.4% when current density increased from 2.5 to 9.3 mA/cm/sup 2/. Further increase in current density does not improve the process efficiency. Removal efficiency of electrochemical process decreased with the increase in initial pH of test solution. However, with the passage of time this difference is diminishing. This may be attributed to the presence of higher amount of hypochloric acid which does not dissociate at lower pH values. Subsequently faster oxidation of nitrite achieved during first few minutes of test runs. Amount of available hypochloric acid reduced at high pH values and oxidation of nitrite reduced subsequently. Rate of nitrite removal found to be increased as the inter-electrode spacing decreased up to an optimal spacing of 3 cm which showed highest nitrite removal. Further reduction in spacing does not augment the removal efficiency probably due to the formation of scale on cathode surface and passivation of electrode which suppressed further oxidation process. (author)

  12. Control factors of partial nitritation for landfill leachate treatment

    Institute of Scientific and Technical Information of China (English)

    LIANG Zhu; LIU Jun-xin

    2007-01-01

    Anaerobic ammonium oxidation (ANAMMOX) technology has potential technical superiority and economical efficiency for the nitrogen removal from landfill leachate, which contains high-strength ammonium nitrogen (NH4+-N) and refractory organics. To complete the ANAMMOX process, a preceding partial nitritation step to produce the appropriate ratio of nitrite/ammonium is a key stage. The objective of this study was to determine the optimal conditions to acquire constant partial nitritation for landfill leachate treatment, and a bench scale fixed bed bio-film reactor was used in this study to investigate the effects of the running factors on the partial nitritation. The results showed that both the dissolved oxygen (DO) concentration and the ammonium volumetric loading rate (Nv) had effects on the partial nitritation. In the controlling conditions with a temperature of 30±1℃, Nv of 0.2-1.0 kg NH4+-N/(m3·d), and DO concentration of 0.8-2.3 mg/L, the steady partial nitritation was achieved as follows: more than 94% partial nitritation efficiency (nitrite as the main product), 60%-74% NH4+-N removal efficiency, and NO2--N/NH4+-N ratio (concentration ratio) of 1.0-1.4 in the effluent.The impact of temperature was related to Nv at certain DO concentration, and the temperature range of 25-30℃ was suitable for treating high strength ammonium leachate. Ammonium-oxidizing bacteria (AOB) could be acclimated to higher FA (free ammonium) in the range of 122-224 mg/L. According to the denaturing gradient gel electrophoresis analysis result of the bio-film in the reactor, there were 25 kinds of 16S rRNA gene fragments, which indicated that abundant microbial communities existed in the bio-film, although high concentrations of ammonium and FA may inhibit the growth of the nitrite-oxidizing bacteria (NOB) and other microorganisms in the reactor.

  13. Modeling the Impact of Ingoing Sodium Nitrite, Sodium Ascorbate, and Residual Nitrite Concentrations on Growth Parameters of Listeria monocytogenes in Cooked, Cured Pork Sausage.

    Science.gov (United States)

    King, Amanda M; Glass, Kathleen A; Milkowski, Andrew L; Seman, Dennis L; Sindelar, Jeffrey J

    2016-02-01

    Sodium nitrite has been identified as a key antimicrobial ingredient to control pathogens in ready-to-eat (RTE) meat and poultry products, including Listeria monocytogenes. This study was designed to more clearly elucidate the relationship between chemical factors (ingoing nitrite, ascorbate, and residual nitrite) and L. monocytogenes growth in RTE meats. Treatments of cooked, cured pork sausage (65% moisture, 1.8% salt, pH 6.6, and water activity 0.98) were based on response surface methodology with ingoing nitrite and ascorbate concentrations as the two main factors. Concentrations of nitrite and ascorbate, including star points, ranged from 0 to 352 and 0 to 643 ppm, respectively. At one of two time points after manufacturing (days 0 and 28), half of each treatment was surface inoculated to target 3 log CFU/g of a five-strain L. monocytogenes cocktail, vacuum packaged, and stored at 7°C for up to 4 weeks. Growth of L. monocytogenes was measured twice per week, and enumerations were used to estimate lag time and growth rates for each treatment. Residual nitrite concentrations were measured on days 0, 4, 7, 14, 21, and 28, and nitrite depletion rate was estimated by using first-order kinetics. The response surface methodology was used to model L. monocytogenes lag time and growth rate based on ingoing nitrite, ascorbate, and the residual nitrite remaining at the point of inoculation. Modeling results showed that lag time was impacted by residual nitrite concentration remaining at inoculation, as well as the squared term of ingoing nitrite, whereas growth rate was affected by ingoing nitrite concentration but not by the remaining residual nitrite at the point of inoculation. Residual nitrite depletion rate was dependent upon ingoing nitrite concentration and was only slightly affected by ascorbate concentration. This study confirmed that ingoing nitrite concentration influences L. monocytogenes growth in RTE products, yet residual nitrite concentration contributes

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

    OpenAIRE

    Larsson, Kristin Anna; Darnerud, Per Ola; Ilbäck, Nils-Gunnar; Merino, Leonardo

    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...

  15. Analisis Kadar Nitrit Pada Daging Sosis dengan Metode Spektrofotometri

    OpenAIRE

    Siregar, Noerdiansyah

    2014-01-01

    Nitrit is an additive that is used as preservative according to the provision’s of national Standart Indonesia (SNI-01-3820-195) use of nitrit in meat has a maximum dosed of 125 mg/kg .purpose of this study was to determine the supermarket are from the Medan city. Sample that in the analysis are the three sausage products with different brands of supermarket location in the Medan city . Nitrit essay performed visible spectrofotometri using a color reagent N-( 1-napthyl)ethylene diamine dihydr...

  16. Calcium and bones

    Science.gov (United States)

    Bone strength and calcium ... calcium (as well as phosphorus) to make healthy bones. Bones are the main storage site of calcium in ... your body does not absorb enough calcium, your bones can get weak or will not grow properly. ...

  17. Get Enough Calcium

    Science.gov (United States)

    ... Calcium Print This Topic En español Get Enough Calcium Browse Sections The Basics Overview Foods and Vitamins ... 2 of 4 sections Take Action! Take Action: Calcium Sources Protect your bones – get plenty of calcium ...

  18. 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 ...

  19. Effects of Ammonium and Nitrite on Growth and Competitive Fitness of Cultivated Methanotrophic Bacteria▿

    OpenAIRE

    Nyerges, Györgyi; Han, Suk-Kyun; Stein, Lisa Y.

    2010-01-01

    The effects of nitrite and ammonium on cultivated methanotrophic bacteria were investigated. Methylomicrobium album ATCC 33003 outcompeted Methylocystis sp. strain ATCC 49242 in cultures with high nitrite levels, whereas cultures with high ammonium levels allowed Methylocystis sp. to compete more easily. M. album pure cultures and cocultures consumed nitrite and produced nitrous oxide, suggesting a connection between denitrification and nitrite tolerance.

  20. Performance of Denitrifying Microbial Fuel Cell with Biocathode over Nitrite

    Science.gov (United States)

    Zhao, Huimin; Zhao, Jianqiang; Li, Fenghai; Li, Xiaoling

    2016-01-01

    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. PMID:27047462

  1. 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...... 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 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...

  2. Low serum total nitrite and nitrate levels in severe leptospirosis

    OpenAIRE

    Kalugalage, Thilini; Rodrigo, Chaturaka; Vithanage, Thamal; Somaratne, Pranitha; de Silva, H. Janaka; Handunnetti, Shiroma; Rajapakse, Senaka

    2013-01-01

    Background The relationship between inducible nitric oxide synthatase activity and disease severity in leptospirosis is unclear. Nitric oxide is converted to nitrites and nitrates, thus nitrite and nitrate levels (NOx) in serum are considered surrogate markers for nitric oxide. NOx are excreted through the kidneys, and elimination is diminished in renal impairment. We assessed the correlation of NOx with disease severity in patients with leptospirosis, compared with healthy controls and non-l...

  3. Mitochondria recycle nitrite back to the bioregulator nitric monoxide

    International Nuclear Information System (INIS)

    Nitric monoxide (NO) exerts a great variety of physiological functions. L-Arginine supplies amino groups which are transformed to NO in various NO-synthase-active isoenzyme complexes. NO-synthesis is stimulated under various conditions increasing the tissue of stable NO-metabolites. The major oxidation product found is nitrite. Elevated nitrite levels were reported to exist in a variety of diseases including HIV, reperfusion injury and hypovolemic shock. Denitrifying bacteria such as Paracoccus denitrificans have a membrane bound set of cytochromes (cyt cd1, cyt bc) which were shown to be involved in nitrite reduction activities. Mammalian mitochondria have similar cytochromes which form part of the respiratory chain. Like in bacteria quinols are used as reductants of these types of cytochromes. The observation of one-e- divergence from this redox-couple to external dioxygen made us to study whether this site of the respiratory chain may also recycle nitrite back to its bioactive form NO. Thus, the aim of the present study was therefore to confirm the existence of a reductive pathway which reestablishes the existence of the bioregulator NO from its main metabolite NO2-. Our results show that respiring mitochondria readily reduce added nitrite to NO which was made visible by nitrosylation of deoxyhemoglobin. The adduct gives characteristic triplet-ESR-signals. Using inhibitors of the respiratory chain for chemical sequestration of respiratory segments we were able to identify the site where nitrite is reduced. The results confirm the ubiquinone/cyt bc1 couple as the reductant site where nitrite is recycled. The high affinity of NO to the heme-iron of cytochrome oxidase will result in an impairment of mitochondrial energy-production. ''Nitrite tolerance'' of angina pectoris patients using NO-donors may be explained in that way. (author)

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

    OpenAIRE

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

    2010-01-01

    The organic nitrite, amyl of nitrite, was initially used as a therapeutic agent in the treatment of angina pectoris in 1867, but was replaced over a decade later by the organic nitrate, nitroglycerin (NTG), due to the ease of administration and longer duration of action. The administration of organic nitrate esters, such as NTG, continues to be used in the treatment of angina pectoris and heart failure during the birth of modern pharmacology. The clinical effectiveness is due to vasodilator a...

  5. 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.

  6. Automated, colorimetric methods for determination of nitrate plus nitrite, nitrite, ammonium and orthophosphate ions in natural water samples

    Science.gov (United States)

    Antweiler, Ronald C.; Patton, Charles J.; Taylor, Howard E.

    1996-01-01

    The apparatus and methods used for the automatic, colorimetric determinations of dissolved nutrients (nitrate plus nitrite, nitrite, ammonium and orthophosphate) in natural waters are described. These techniques allow for the determination of nitrate plus nitrite for the concentration range 0.02 to 8 mg/L (milligrams per liter) as N (nitrogen); for nitrite, the range is 0.002 to 1.0 mg/L as N; for ammonium, the range is 0.006 to 2.0 mg/L as N; and for orthophosphate, the range is 0.002 to 1.0 mg/L as P (phosphorus). Data are presented that demonstrate the accuracy, precision and quality control of the methods.

  7. 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, exhausti

  8. 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. PMID:26743589

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

    Science.gov (United States)

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

    2016-01-01

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

  10. Synthesis and intracrystalline oxidation of nitrite-intercalated layered double hydroxides

    International Nuclear Information System (INIS)

    Nitrite-intercalated LDHs could be prepared by a two-stage process that involves coprecipitation in the presence of nitrite ions followed by stirring the product with excess of nitrite ions. The nitrite ion lies flat in these LDHs with its c2-axis lying approximately perpendicular to the crystallographic c-axis. The interlayer nitrite ions in these LDHs could be quantitatively oxidized to nitrate ions using H2O2 solution. In the LDHs thus obtained the nitrate ion lies flat with its c3-axis parallel to the crystallographic c-axis (D3h symmetry) in the interlayer region resulting in lower basal spacing. - Graphical abstract: Nitrite-intercalated LDHs could be prepared by a two-stage process that involves coprecipitation in the presence of nitrite ions followed by stirring the product with excess of nitrite ions. The interlayer nitrite ions in these LDHs could be quantitatively oxidized to nitrate ions

  11. Nitrogen cycling in the secondary nitrite maximum of the eastern tropical North Pacific off Costa Rica

    Science.gov (United States)

    Buchwald, Carolyn; Santoro, Alyson E.; Stanley, Rachel H. R.; Casciotti, Karen L.

    2015-12-01

    Nitrite is a central intermediate in the marine nitrogen cycle and represents a critical juncture where nitrogen can be reduced to the less bioavailable N2 gas or oxidized to nitrate and retained in a more bioavailable form. We present an analysis of rates of microbial nitrogen transformations in the oxygen deficient zone (ODZ) within the eastern tropical North Pacific Ocean (ETNP). We determined rates using a novel one-dimensional model using the distribution of nitrite and nitrate concentrations, along with their natural abundance nitrogen (N) and oxygen (O) isotope profiles. We predict rate profiles for nitrate reduction, nitrite reduction, and nitrite oxidation throughout the ODZ, as well as the contributions of anammox to nitrite reduction and nitrite oxidation. Nitrate reduction occurs at a maximum rate of 25 nM d-1 at the top of the ODZ, at the same depth as the maximum rate of nitrite reduction, 15 nM d-1. Nitrite oxidation occurs at maximum rates of 10 nM d-1 above the secondary nitrite maximum, but also in the secondary nitrite maximum, within the ODZ. Anammox contributes to nitrite oxidation within the ODZ but cannot account for all of it. Nitrite oxidation within the ODZ that is not through anammox is also supported by microbial gene abundance profiles. Our results suggest the presence of nitrite oxidation within the ETNP ODZ, with implications for the distribution and physiology of marine nitrite-oxidizing bacteria, and for total nitrogen loss in the largest marine ODZ.

  12. Spectrophotometric determination of nitrite and nitrate using phosphomolybdenum blue complex.

    Science.gov (United States)

    Zatar, N A; Abu-Eid, M A; Eid, A F

    1999-11-15

    A method for spectrophotometric determination of nitrite and nitrate is described. This method is based on the reduction of phosphomolybdic acid to phosphomolybdenum blue complex by sodium sulfide. The obtained phosphomolybdenum blue complex is oxidized by the addition of nitrite and this causes a reduction in intensity of the blue color. The absolute decrease in the absorbance of the blue color or the rate of its decrease is found to be directly proportional to the amount of nitrite added. The absorbance of the phosphomolybdenum blue complex is monitored spectrophotometrically at 814 nm and related to the concentration of nitrite present. The effect of different factors such as acidity, stability of the complex, time, temperature, phosphate concentration, molybdenum concentration, sodium sulfide concentration and the tolerance amount of other ions have been reported. Maximum absorbance is at 814 nm. The range of linearity using the conventional method is 0.5-2.0 ppm with molar absorptivity of 1.1 x 10(4) l mol(-1) cm(-1). and a relative standard deviation of 2.6% for five measurements. The range of linearity using the reaction rate method is 0.2-3.6 ppm with a relative standard deviation of 2.4% for five measurements. The method is applied for determination of nitrite and nitrate in water, meat products and vegetables. PMID:18967772

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

    Directory of Open Access Journals (Sweden)

    PeterDungel

    2013-05-01

    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.

  14. 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 ...

  15. Coronary Calcium Scan

    Science.gov (United States)

    ... the NHLBI on Twitter. What Is a Coronary Calcium Scan? A coronary calcium scan is a test ... you have calcifications in your coronary arteries. Coronary Calcium Scan Figure A shows the position of the ...

  16. 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 ...

  17. 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 ...

  18. Calcium in diet

    Science.gov (United States)

    Diet - calcium ... Calcium is one of the most important minerals for the human body. It helps form and maintain healthy teeth and bones. A proper level of calcium in the body over a lifetime can help ...

  19. 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 ...

  20. Generation of nitric oxide from nitrite by carbonic anhydrase

    DEFF Research Database (Denmark)

    Aamand, Rasmus; Dalsgaard, Thomas; Jensen, Frank B;

    2009-01-01

    In catalyzing the reversible hydration of CO2 to bicarbonate and protons, the ubiquitous enzyme carbonic anhydrase (CA) plays a crucial role in CO2 transport, in acid-base balance, and in linking local acidosis to O2 unloading from hemoglobin. Considering the structural similarity between...... bicarbonate and nitrite, we hypothesized that CA uses nitrite as a substrate to produce the potent vasodilator nitric oxide (NO) to increase local blood flow to metabolically active tissues. Here we show that CA readily reacts with nitrite to generate NO, particularly at low pH, and that the NO produced in...... effectively in catalysis. Taken together, our results reveal a novel nitrous anhydrase enzymatic activity of CA that would function to link the in vivo main end products of energy metabolism (CO2/H+) to the generation of vasoactive NO. The CA-mediated NO production may be important to the correlation between...

  1. Generation of nitric oxide from nitrite by carbonic anhydrase:

    DEFF Research Database (Denmark)

    Aamand, Rasmus; Dalsgaard, Thomas; Jensen, Frank Bo;

    2009-01-01

    In catalyzing the reversible hydration of CO2 to bicarbonate and protons, the ubiquitous enzyme carbonic anhydrase (CA) plays a crucial role in CO2 transport, in acid-base balance, and in linking local acidosis to O2 unloading from hemoglobin. Considering the structural similarity between...... bicarbonate and nitrite, we hypothesized that CA uses nitrite as a substrate to produce the potent vasodilator nitric oxide (NO) to increase local blood flow to metabolically active tissues. Here we show that CA readily reacts with nitrite to generate NO, particularly at low pH, and that the NO produced in...... effectively in catalysis. Taken together, our results reveal a novel nitrous anhydrase enzymatic activity of CA that would function to link the in vivo main end products of energy metabolism (CO2/H+) to the generation of vasoactive NO. The CA-mediated NO production may be important to the correlation between...

  2. Spectrophotometric determination of nitrite in simulated Purex Process solutions

    International Nuclear Information System (INIS)

    A spectrophotometric method for nitrite determination in simulated Purex Process solutions is presented, utilizing the Griess reagent for the formation of the coloured azocompound with an absorption maximum at 525 nm. Molar absortivity was 36,262 and the sensitivity of the method 10-6M for nitrite. The calibration curve is linear in the range of 2 to 30μg NO-2/25 ml in cells of 1 cm optical path. The method can be used in the presence of uranium up to limits of an U/NO-2 ratio of 150. Test solutions were prepared to simulate composition and concentrations as obtained by irradiating standard fuel with a neutro flux of 3.2 x 1013 n.s-1.cm-2, with a burn-up value of 33,000 Mwd/T and cooling time of two years. Nitrite determinations in these solutions were accurate within limits of 5%. (Author)

  3. 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.

  4. Biological Nitrogen Removal through Nitritation Coupled with Thiosulfate-Driven Denitritation.

    Science.gov (United States)

    Qian, Jin; Zhou, Junmei; Zhang, Zhen; Liu, Rulong; Wang, Qilin

    2016-01-01

    A novel biological nitrogen removal system based on nitritation coupled with thiosulfate-driven denitritation (Nitritation-TDD) was developed to achieve a high nitrogen removal rate and low sludge production. A nitritation sequential batch reactor (nitritation SBR) and an anoxic up-flow sludge bed (AnUSB) reactor were applied for effective nitritation and denitritation, respectively. Above 75% nitrite was accumulated in the nitritation SBR with an influent ammonia loading rate of 0.43 kg N/d/m(3). During Nitritation-TDD operation, particle sizes (d50) of the sludge decreased from 406 to 225 um in nitritation SBR and from 327-183 um in AnUSB reactor. Pyrosequencing tests revealed that ammonium-oxidizing bacteria (AOB) population was stabilized at approximately 7.0% (calculated as population of AOB-related genus divided by the total microbial population) in the nitritation SBR. In contrast, nitrite-oxidizing bacteria (NOB) population decreased from 6.5-0.6% over the same time, indicating the effective nitrite accumulation in the nitritation SBR. Thiobacillus, accounting for 34.2% in the AnUSB reactor, was mainly responsible for nitrogen removal via autotrophic denitritation, using an external source of thiosulfate as electron donor. Also, it was found that free nitrous acid could directly affect the denitritation activity. PMID:27272192

  5. The intramolecular electron transfer between copper sites of nitrite reductase

    DEFF Research Database (Denmark)

    Farver, O; Eady, R R; Abraham, Z H;

    1998-01-01

    The intramolecular electron transfer (ET) between the type 1 Cu(I) and the type 2 Cu(II) sites of Alcaligenes xylosoxidans dissimilatory nitrite reductase (AxNiR) has been studied in order to compare it with the analogous process taking place in ascorbate oxidase (AO). This internal process is......(I) and the trinuclear copper centre in ascorbate oxidase, and the characteristics of the internal ET processes of these enzymes are compared. The data are consistent with the faster ET observed in nitrite reductase arising from a more advantageous entropy of activation when compared with ascorbate...

  6. Association between calcium intake, parathormone levels and blood pressure during pregnancy

    Directory of Open Access Journals (Sweden)

    Anibal Nieto

    2009-06-01

    Full Text Available Purpose: To evaluate the association between calcium intake from diet, calciotropic hormones (PTH, PTH-rp, vasoactive regulators (endothelin, nitric oxide and blood pressure levels during pregnancy, birth and puerperium.Method: In a prospective study 149 healthy normotensive primigravidas were followed-up from 15 weeks of gestation to puerperium. Daily calcium intake, calciuria, PTH, PTH-rp, endothelin, nitrite-nitrate, and Holter Test were assessed. Linear regression models were performed to evaluate the association between calcium intake, blood pressure levels and the laboratory tests. Multivariate regression models were performed to control potential confounders.Results: A significant increase of calcium intake during pregnancy was observed (931±301 mg/day to 1,195±467 mg/day, p<0.001. Plasma PTH-rp, endothelin, and nitrite-nitrate levels did not change during pregnancy. Among the women 38 (25.4% had low calcium intake (<800 mg/day with a larger increase of systolic and diastolic blood pressure during pregnancy (p=0.04 birth (p=0.006 and puerperium (p=0.01. After adjusting for other factors the multivariate analyses showed statistical association between low calcium intake, high parathormone levels and high systolic blood pressure levels during pregnancy (p=0.002.Conclusion: Low calcium intake during pregnancy is associated with a larger increase of systolic blood pressure and high parathormone levels.

  7. Artificial electron donors for nitrate and nitrite reductases usable as mediators in amperometric biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Strehlitz, B. (Umweltforschungszentrum Leipzig-Halle GmbH, Leipzig (Germany)); Gruendig, B. (Institut fuer Chemo- und Biosensorik, Muenster-Roxel (Germany)); Vorlop, K.D. (Bundesforschungsanstalt fuer Landwirtschaft, Braunschweig (Germany). Inst. fuer Technologie); Bartholmes, P. (Witten-Herdecke Univ., Witten (Germany). Inst. fuer Biochemie); Kotte, H. (Umweltforschungszentrum Leipzig-Halle GmbH, Leipzig (Germany)); Stottmeister, U. (Umweltforschungszentrum Leipzig-Halle GmbH, Leipzig (Germany))

    1994-07-01

    Various nitrate and nitrite reductases are capable of accepting electrons from artificial donors. Combining these redox active donors with an amperometric redox electrode which is covered with an immobilized layer of such a nitrate or nitrite reductase, new enzyme sensors can be created for the detection of nitrate or nitrite, respectively. A range of suitable electron donors for nitrate reductases and nitrite reductase from different sources have been selected and characterized by electrochemical methods. (orig.)

  8. Study on the nitrite and nitrate levels changes by drying and frying processing in vegetables

    OpenAIRE

    Sadeghi, E; K Sharafi; A Almasi; M Dayhim; E Azizi; M Ghayebzadeh

    2014-01-01

    Background and objectives: Nitrate and nitrite threaten the human health. According to recent research works, one of the great sources of exposure to nitrate and nitrite in human diet is vegetables. The aim of this study is to determine the effect of drying and frying processes on nitrate and nitrite levels in abundant vegetables. Materials and methods: In this descriptive – analytical study, 180 vegetable samples were taken randomly from Kermanshah markets. Nitrite and nitrate concentrati...

  9. 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...

  10. Measurement of Nitrite in Blood Samples Using the Ferricyanide-Based Hemoglobin Oxidation Assay

    OpenAIRE

    Piknova, Barbora; Schechter, Alan N.

    2011-01-01

    Nitrite is currently recognized as a biomarker of the state of nitric oxide metabolism. Therefore, assessing nitrite levels in various organs and compartments is an important issue. As nitrite levels in most organs and tissues are low (in high nanomolar or low micromolar range) several new sensitive methods for quantifying nitrite in various biological samples have been developed. Chemiluminescence, combined with tri-iodide reducing solution, is currently considered the most sensitive method,...

  11. Regulation of nitrite transport in red blood cells by hemoglobin oxygen fractional saturation

    OpenAIRE

    Vitturi, Dario A; Teng, Xinjun; Toledo, José C.; Matalon, Sadis; Lancaster, Jack R.; Patel, Rakesh P.

    2009-01-01

    Allosteric regulation of nitrite reduction by deoxyhemoglobin has been proposed to mediate nitric oxide (NO) formation during hypoxia. Nitrite is predominantly an anion at physiological pH, raising questions about the mechanism by which it enters the red blood cell (RBC) and whether this is regulated and coupled to deoxyhemoglobin-mediated reduction. We tested the hypothesis that nitrite transport by RBCs is regulated by fractional saturation. Using human RBCs, nitrite consumption was faster ...

  12. Nanoliposomal Growth Hormone and Sodium Nitrite Release from Silicone Fibers Reduces Thrombus Formation Under Flow.

    Science.gov (United States)

    Salehi-Nik, Nasim; Amoabediny, Ghassem; Banikarimi, Seyedeh Parnian; Pouran, Behdad; Malaie-Balasi, Zahra; Zandieh-Doulabi, Behrouz; Klein-Nulend, Jenneke

    2016-08-01

    Biocompatibility of artificial lungs can be improved by endothelialization of hollow fibers. Bioavailability of growth-inducing and anti-thrombotic agents on the hollow fiber-blood interface inhibits thrombosis. We investigated if nanoliposomal growth-inducing growth hormone (nGH) and anti-thrombotic sodium nitrite (nNitrite) incorporation into collagen-coating on silicone hollow fibers improves blood biocompatibility by increasing endothelial cell growth and nitrite bioavailability under flow. Nitrite production rate was assessed under varying flow conditions. Finite element (FE) modeling was used to simulate nitrite transport within the parallel-plate flow chamber, and nitrite bioavailability on the fiber-blood interface at 1-30 dyn/cm(2) shear stress. Endothelial cell number on fibers coated with nNitrite-nGH-collagen conjugate was 1.5-fold higher than on collagen-coated fibers. For collagen-coated fibers, nitrite production reached a maximum at 18 dyn/cm(2) shear stress. When fibers were coated with nNitrite-nGH-collagen conjugate, nitrite production increased continuously by increasing shear stress. FE modeling revealed that nitrite concentrations at the fiber-blood interface were affected by shear stress-induced nitrite production, and diffusion/convection-induced nitrite removal. Highest nitrite concentrations and lowest thrombus deposition were observed on fibers coated with nNitrite-nGH-collagen conjugate exposed to 6-12 dyn/cm(2) shear stress. In conclusion, our results suggest that nNitrite-nGH-Col conjugate coatings promote endothelialization of silicone hollow fibers in biohybrid artificial lungs. PMID:26762283

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

    Directory of Open Access Journals (Sweden)

    Cassilda Pereira

    2013-01-01

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

  14. 21 CFR 172.177 - Sodium nitrite used in processing smoked chub.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium nitrite used in processing smoked chub. 172... FOOD FOR HUMAN CONSUMPTION Food Preservatives § 172.177 Sodium nitrite used in processing smoked chub. The food additive sodium nitrite may be safely used in combination with salt (NaCl) to aid...

  15. 21 CFR 250.100 - Amyl nitrite inhalant as a prescription drug for human use.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 4 2010-04-01 2010-04-01 false Amyl nitrite inhalant as a prescription drug for... Prescription Status of Specific Drugs § 250.100 Amyl nitrite inhalant as a prescription drug for human use. (a) Amyl nitrite inhalant has been available over-the-counter for emergency use by the patient in...

  16. 75 FR 29534 - Inorganic Nitrates-Nitrite, Carbon and Carbon Dioxide, and Sulfur Registration Review; Draft...

    Science.gov (United States)

    2010-05-26

    ... AGENCY Inorganic Nitrates-Nitrite, Carbon and Carbon Dioxide, and Sulfur Registration Review; Draft... draft ecological risk assessment for the registration review of inorganic nitrates - nitrites, carbon... occur for all inorganic nitrates- nitrites, carbon and carbon dioxide uses, as well as gas...

  17. 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... products containing sodium nitrite labeled for the treatment of cyanide poisoning and unapproved injectable... products containing sodium nitrite or sodium thiosulfate that are labeled for the treatment of...

  18. ACUTE TOXICITY OF AMMONIA AND NITRITE TO CUTTHROAT TROUT FRY

    Science.gov (United States)

    The toxicity of ammonia and of nitrite was tested on cutthroat trout (Salmo clarki) fry (1-3 g) for periods up to a month in eight laboratory flow-through bioassays. Median lethal concentration (LC50) values for ammonia (mg/liter un-ionized NH3) were 0.5-0.8 for 96 hours, and 0.3...

  19. Evaluation of nitrate and nitrite destruction/separation technologies

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D.T.

    1997-08-29

    This report describes and evaluates four types of nitrate and nitrite destruction and separation technologies that could be used to treat the aqueous, alkaline, nitrate-bearing mixed waste that is generated by the In-Tank Precipitation (ITP) process at the Savannah River Site (SRS). The technologies considered in this report include thermal, hydrothermal, chemical, and electrochemical technologies.

  20. One-stage partial nitritation and anammox in membrane bioreactor.

    Science.gov (United States)

    Huang, Xiaowu; Sun, Kaihang; Wei, Qiaoyan; Urata, Kohei; Yamashita, Yuki; Hong, Nian; Hama, Takehide; Kawagoshi, Yasunori

    2016-06-01

    Partial nitritation and anammox (PN/A) was applied in a lab-scale membrane bioreactor (MBR) to investigate its technical feasibility for treating ammonium-rich wastewater with low C/N ratio. The bacterial community was analyzed by molecular cloning and 16S rRNA sequence analysis. Partial nitritation (PN) was first realized in MBR by seeding aerobic activated sludge. With dissolved oxygen control, a steady effluent mixture with NO2 (-)-N/NH4 (+)-N ratio of 1.13 ± 0.08 was generated from the PN process. Subsequently, the MBR was seeded with anammox biomass on day 59. After running 300 days, the one-stage PN/A achieved a maximum nitrogen removal rate of 1.45 kg N/m(3)/day at the nitrogen removal efficiency of 89.5 %. Microbial community analysis revealed that Nitrosomonas sp. HKU and Nitrosospira sp. YKU corresponded to nitritation; meanwhile, Candidatus Brocadia TKU sp. accounted for nitrogen removal of the PN/A system. Specifically, Nitrosomonas sp. were enriched in the reactor at the PN/A phase and then conquered Nitrosospira sp. to be the predominant ammonia oxidizers. Nitrite oxidizers and denitrifiers were detected in symbiosis with aforementioned microbes. Denitrification promised potential plus nitrogen depletion. The present one-stage PN/A process allows a significant decrease in operational costs compared with classical nitrification/denitrification. PMID:26916267

  1. Serum nitrite levels in Sri Lankan patients with leptospirosis

    Institute of Scientific and Technical Information of China (English)

    Rohini I Gunaratna; Shiroma M Handunnetti; MRC Bulathsinghalage; Pranitha Somaratne; Ananda Jayanaga; HJ de Silva; Senaka Rajapakse

    2012-01-01

    Objective:To determine whether blood nitrite levels are elevated in patients with leptospirosis. Methods: Male patients fulfilling clinical and epidemiological criteria for a diagnosis of leptospirosis were recruited. Those with MAT titre of≥400 together with those seroconverting to a titer of≥200 were included in the analysis. Serum nitrite levels were measured in these patients and age, sex matched healthy controls. Results:Patients from 3 hospitals (n=75) were screened during a 3 month period from 28th June to 3rd September 2009, of whom 20 were eligible for the study. Serum nitrite levels were found to be significantly higher in patients with acute leptospirosis [n=20, (0.359±0.229)μM] compared to controls [(n=13,(0.216±0.051)μM] (P=0.014). A significant correlation was also observed between the MAT titre and the day of illness (r = 0.547; P<0.0001). Conclusions: Serum nitrite levels are higher in patients with acute leptospirosis compared to age and sex matched controls. No correlation could be assessed with severity of illness, as sample size was inadequate to determine this.

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

    Science.gov (United States)

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

    2015-12-01

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

  3. Nitrate metabolism in tobacco leaves overexpressing Arabidopsis nitrite reductase.

    Science.gov (United States)

    Davenport, Susie; Le Lay, Pascaline; Sanchez-Tamburrrino, Juan Pablo

    2015-12-01

    Primary nitrogen assimilation in plants includes the reduction of nitrite to ammonium in the chloroplasts by the enzyme nitrite reductase (NiR EC:1.7.7.1) or in the plastids of non-photosynthetic organs. Here we report on a study overexpressing the Arabidopsis thaliana NiR (AtNiR) gene in tobacco plants under the control of a constitutive promoter (CERV - Carnation Etched Ring Virus). The aim was to overexpress AtNiR in an attempt to alter the level of residual nitrite in the leaf which can act as precursor to the formation of nitrosamines. The impact of increasing the activity of AtNiR produced an increase in leaf protein and a stay-green phenotype in the primary transformed AtNiR population. Investigation of the T1 homozygous population demonstrated elevated nitrate reductase (NR) activity, reductions in leaf nitrite and nitrate and the amino acids proline, glutamine and glutamate. Chlorophyl content of the transgenic lines was increased, as evidenced by the stay-green phenotype. This reveals the importance of NiR in primary nitrogen assimilation and how modification of this key enzyme affects both the nitrogen and carbon metabolism of tobacco plants. PMID:26447683

  4. Calcium and Vitamin D

    Science.gov (United States)

    ... Home › Patients › Treatment › Calcium/Vitamin D Calcium/Vitamin D Getting enough calcium and vitamin D is essential ... counter medications and calcium supplements. What is Vitamin D and What Does it Do? Vitamin D plays ...

  5. Nitrogen removal via nitrite from municipal landfill leachate

    Institute of Scientific and Technical Information of China (English)

    WU Lina; PENG Chengyao; ZHANG Shujun; PENG Yongzhen

    2009-01-01

    A system consisting of a two-stage up-flow anaerobic sludge blanket (UASB),an anoxic/aerobic (A/O) reactor and a sequencing batch reactor (SBR),was used to treat landfill leachate.During operation,denitrification and methanogenesis took place simultaneously in the first stage UASB (UASB1),and the effluent chemical oxygen demand (COD) was further removed in the second stage UASB (UASB2).Then the denitrification of nitrite and nitrate in the returned sludge by using the residual COD was accomplished in the A/O reactor,and ammonia was removed via nitrite in it.Last but not least,the residual ammonia was removed in SBR as well as nitrite and nitrate which were produced by nitrification.A system consisting of a two-stage UASB and an A/O reactor was used to achieve the stable short-cut nitrification in the first stage (60 d).The effluent of stage one was treated by SBR in the second stage (60 d).The results over 120 d were as follows: when the total nitrogen (TN) concentration of influent leachate was about 2500 mg/L and the ammonia nitrogen concentration was about 2000 mg/L,the short-cut nitrification with 85%-90% nitrite accumulation was achieved stably in the A/O reactor.The TN and ammonia nitrogen removal efficiencies of the system were 98% and 97%,respectively.The residual ammonia,nitrite and nitrate which were produced by nitrification in the A/O reactor could be washed out almost completely in SBR.The TN and ammonia nitrogen concentrations of final effluent were about 39 mg/L and 12 mg/L,respectively.

  6. Importance of Calcium

    OpenAIRE

    TANDOĞAN, Berivan; ULUSU, N. Nuray

    2005-01-01

    Calcium is the most abundant mineral in the body. Calcium regulates many cellular processes and has important structural roles in living organisms. Skeletal muscle structure and function, polymerisation of fibrin and the conduction of impulses in the nervous system are regulated by calcium. Calcium is an important intracellular messenger in protozoa, plants, and animals. Calcium-transporting systems which are located in the plasma membrane and in the organelles, regulate the ionic concentrati...

  7. Effects of seawater salinity on nitrite accumulation in short-range nitrification to nitrite as end product

    Institute of Scientific and Technical Information of China (English)

    YU De-shuang; PENG Yong-zhen; ZHANG Kui

    2004-01-01

    The effect of seawater salinity on nitrite accumulation in short-range nitrification to nitrite as the end productwas studied by using a SBR. Experimental results indicated that the growth of nitrobacteria was inhibited and veryhigh levels of nitrite accumulation at different salinities were achieved under the conditions of 25-28 ℃, pH 7.5-8.0, and the influent ammonia nitrogen of 40-70 mg/L when seawater flow used to flush toilet was less than 35%(salinity 12393 mg/L, Cl- 6778 mg/L) of total domestic wastewater flow, which is mainly ascribed to much highchlorine concentration of seawater. Results showed that high seawater salinity is available for short-range nitrificationto nitrite as the end product. When the seawater flow used to flush toilet accounting for above 70% of the totaldomestic wastewater flow, the removal efficiency of ammonia was still above 80% despite the removal of organicsdeclined obviously(less than 60% ). It was found that the effect of seawater salinity on the removal of organics wasnegative rather than positive one as shown for ammonia removal.

  8. Model-based evaluation on the conversion ratio of ammonium to nitrite in a nitritation process for ammonium-rich wastewater treatment

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-ming; YANG Qi; ZENG Guang-ming; A. Cornelius; K. H. Rosenwinkel; S. Kunst; D. Weichgrebe

    2004-01-01

    Modeling for nitritation process was discussed and analyzed quantlitatively for the factors that influence nitrite accumulation. The results indicated that pH, inorganic carbon source and Hydraulic Retention Time(HRT) as well as biomass concentration are the main factors that influenced the conversion ratio of ammonium to nitrite. A constant high pH can lead to a high nitritation rate and results in high conversion ratio on condition that free ammonia inhibition do not happen. In a CSTR system, without pH control, this conversion ratio can be monitored by pH variation in the reactor. The pH goes down far from the inlet level means a strongly nitrite accumulation. High concentration of alkalinity can promoted the conversion ratio by means of accelerating the nitritation rate through providing sufficient inorganic carbon source(carbon dioxide). When inorganic carbon source was depleted, the nitritation process stopped. HRT adjustment could be an efficient way to make the nitritation system run more flexible, which to some extent can meet the requirements of the fluctuant of inlet parameters such as ammonium concentration, pH, and temperature and so on. Biomass concentration is the key point, especially for a CSTR system in steady state, which was normally circumscribed by the characteristics of bacteria and may also affected by aeration mode and can be increased by prolonging the HRT on the condition of no nitrate accumulation when no recirculation available. The higher the biomass concentration is, the better the nitrite accumulation can be obtained.

  9. 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

    of the growth of Clostridium botulinum. According to an assessment report by the European Food Safety Authority (The EFSA Journal, 14, p. 1-134, 2003) all evidence points to that it is the added amount of nitrite rather than the residual amount of nitrite in the product which exerts the antimicrobial effect....... Nitrite also has a desirable anti-oxidant activity and contributes to the formation of pleasant flavours. A systematic literature review on the function and use of nitrite in meat leads to a tentative first conclusion that if the level of nitrite added to meat products is sufficient to protect against...... possible toxin formation from C. botulinum, then the other technological reasons for using nitrite can be accomplished within the range of 50-100 mg/kg added nitrite, as is recommended by European Food Safety Authority (EFSA), see the reference above. A similar conclusion was earlier reached after a large...

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

    DEFF Research Database (Denmark)

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

    2016-01-01

    Striped catfish (Pangasianodon hypophthalmus) are farmed intensively at high stocking densities in Vietnam where they are likely to encounter environmental hypercapnia as well as occasional high levels of aquatic nitrite. Nitrite competes with Cl- for uptake at the branchial HCO3-/Cl- exchanger...... to a reduced nitrite uptake. To assess the effect of hypercapnia on nitrite uptake, fish were cannulated in the dorsal aorta, allowing repeated blood sampling for measurements of haemoglobin derivatives, plasma ions and acid-base status during exposure to 0.9 mM nitrite alone and in combination with...... acute and 48 h acclimated hypercapnia over a period of 72 h. Nitrite uptake was initially reduced during the hypercapnia-induced acidosis, but after pH recovery the situation was reversed, resulting in higher plasma nitrite concentrations and lower functional haemoglobin levels that eventually caused...

  11. Role of nitrate and nitrite in the induction of nitrite reductase in leaves of barley seedlings

    Science.gov (United States)

    Aslam, M.; Huffaker, R. C.

    1989-01-01

    The role of NO3- and NO2- in the induction of nitrite reductase (NiR) activity in detached leaves of 8-day-old barley (Hordeum vulgare L.) seedlings was investigated. Barley leaves contained 6 to 8 micromoles NO2-/gram fresh weight x hour of endogenous NiR activity when grown in N-free solutions. Supply of both NO2- and NO3- induced the enzyme activity above the endogenous levels (5 and 10 times, respectively at 10 millimolar NO2- and NO3- over a 24 hour period). In NO3(-)-supplied leaves, NiR induction occurred at an ambient NO3- concentration of as low as 0.05 millimolar; however, no NiR induction was found in leaves supplied with NO2- until the ambient NO2- concentration was 0.5 millimolar. Nitrate accumulated in NO2(-)-fed leaves. The amount of NO3- accumulating in NO2(-)-fed leaves induced similar levels of NiR as did equivalent amounts of NO3- accumulating in NO3(-)-fed leaves. Induction of NiR in NO2(-)-fed leaves was not seen until NO3- was detectable (30 nanomoles/gram fresh weight) in the leaves. The internal concentrations of NO3-, irrespective of N source, were highly correlated with the levels of NiR induced. When the reduction of NO3- to NO2- was inhibited by WO4(2-), the induction of NiR was inhibited only partially. The results indicate that in barley leaves in NiR is induced by NO3- directly, i.e. without being reduced to NO2-, and that absorbed NO2- induces the enzyme activity indirectly after being oxidized to NO3- within the leaf.

  12. Recyclable Magnetic Mesoporous Nanocomposite with Improved Sensing Performance toward Nitrite.

    Science.gov (United States)

    Zhang, Yihe; Su, Zisheng; Li, Bin; Zhang, Liming; Fan, Di; Ma, Heping

    2016-05-18

    A magnetic nanomaterial for nitrite ion detection was demonstrated in the present study. This nanomaterial was prepared by grafting a rhodamine 6G derivative (denoted as Rh 6G-OH) into the channels of core-shell magnetic mesoporous silica nanospheres. The nanocomposite (denoted as Fe3O4@Rh 6G) showed large surface area and improved fluorescent performance to accumulate and recognize NO2(-), and its superparamagnetic behavior played an important role in reusability. The fluorescent intensity decreased linearly along with the NO2(-) concentration in the range of 1-50 μM, and the detection limit was estimated to be 0.8 μM, which was much lower than the maximum limit of nitrite ion in drinking water (65 μM) recommended by World Health Organization. Importantly, Fe3O4@Rh 6G could be magnetically collected and effectively reutilized after six test cycles. PMID:27115527

  13. PENELITIAN TOKSISITAS AKUT NATRIUM NITRIT PADA HEWAN UJI TIKUS

    Directory of Open Access Journals (Sweden)

    Sri Endreswari

    2012-10-01

    Full Text Available The acute toxicity study of sodium nitrite in the period of observation for 14 days has been carried out on adult male and female rats. The substance was administered orally iu the form of solution in distilled water. Each animal was observed carefully for six hours after administration, continued twice daily for 1.4 days, those including general appearance, body weight changes, signs of toxicity mortality and gross pathology finding. The signs of toxicity were tremor, ataxia and convulsion; mortalities were occurred in about two hours after administration. Some animal recovered after two - four hours. The LD50 in male mice was 121 (86,6-169,4 mg/kg b.w., in female was 116 (86-155.4 mg/kg b.w. Based on the LD50 value, sodium nitrite is classified as moderately toxic substances.

  14. 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.

  15. Nitrite and Nitrate Removal Efficiencies of Soil Aquifer Treatment Columns

    OpenAIRE

    GÜNGÖR, Kerem; ÜNLÜ, Kahraman

    2005-01-01

    Bench-scale soil column experiments were performed to examine the effects of soil type and infiltration conditions on the removal efficiencies of wastewater nitrites and nitrates during the biological ripening phase of soil aquifer treatment (SAT) columns. SAT was simulated in three 1-m-high soil columns packed with 3 different natural agricultural soils having sandy clay loam (SCL), loamy sand (LS) and sandy loam (SL) textures. All columns were equipped with tensiometers and soil-wa...

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

    Science.gov (United States)

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

    2015-01-01

    Nitrate reduction is considered to be a minor microbial pathway in the oxidation of mangrove-derived organic matter due to a limited supply of nitrate in mangrove soils. At a limited availability of this electron acceptor compared to the supply of degradable carbon, nitrate ammonification is thought to be the preferential pathway of nitrate reduction. Mangrove forest mutually differ in their productivity, which may lead to different available carbon to nitrate ratios in their soil. Hence, nitrate ammonification is expected to be of more importance in high- compared to low-productive forests. The hypothesis was tested in flow-through reactors that contain undisturbed mangrove soils from high-productive Avicennia germinans and Rhizophora mangle forests in Florida and low-productive Avicennia marina forests in Saudi Arabia. Nitrate was undetectable in the soils from both regions. It was assumed that a legacy of nitrate ammonification would be reflected by a higher ammonium production from these soils upon the addition of nitrate. Unexpectedly, the soils from the low-productive forests in Saudi Arabia produced considerably more ammonium than the soils from the high-productive forests in Florida. Hence, other environmental factors than productivity must govern the selection of nitrate ammonification or denitrification. A rather intriguing observation was the 1:1 production of nitrite and ammonium during the consumption of nitrate, more or less independent from sampling region, location, sampling depth, mangrove species and from the absence or presence of additional degradable carbon. This 1:1 ratio points to a coupled production of ammonium and nitrite by one group of nitrate-reducing microorganisms. Such a production of nitrite will be hidden by the presence of active nitrite-reducing microorganisms under the nitrate-limited conditions of most mangrove forest soils. PMID:25784903

  17. Measurement and Correlation of Solubilityof Ethyl Nitrite in Mixed Solvent

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    An experimental apparatus was used to measure the solubility of ethylnitrite in mixedsolvents under the lower pressure and higher temperature. The solubilitiesof ethyl nitrite inmixed solvents of ethanol-water at 15° C---40° C and ethanol-diethyloxalate at 20° C---40° C weredetermined. A Henry constant model has been improved, and the interaction parameters havebeen fitted from experimental data. The calculation results have been compared withexperimental data; the results obtained are satisfactory.

  18. Environental assessment of methane oxidizers nitrite driven bacteria

    OpenAIRE

    VAELLO LÓPEZ, MARIA TERESA

    2013-01-01

    The nitrite-dependent anaerobic methane oxidation (N-DAMO) bacteria has been discovered in the last decade and there is little known about its environmental distribution and contribution to the oxidation of methane (CH4). Because CH4 is of environmental concern due to its contribution to global warming, it has become very important to look for ways to reduce it. The purpose of this thesis is the acquisition of established molecular tools and their application in microbial ecology investiga...

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

    OpenAIRE

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

    1982-01-01

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

  20. 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.

  1. Cardboard versus sterile containers: more nitrite-positive urinalysis results?

    Science.gov (United States)

    Eley, Rhiannon

    Urinalysis is a frequently performed test that provides valuable information as to the health of individuals. The presence of nitrites in the urine may indicate infection. Antibiotic therapy is commonly started following the results of dipstick urine taken from non-sterile urine samples. This is especially prevalent in men who are immobile, because sterile containers large enough to hold a full bladder of urine are not available (at the author's trust). Urine samples were taken from 25 male A&E patients in a sterile container. Half of each sample was decanted into an ordinary cardboard urine bottle and both samples were then tested using dipstick urinalysis after 1 minute and after 10 minutes to see if there was a difference in the presence of nitrites between the two container types. After 10 minutes, 21 of the 25 samples showed a positive nitrite dipstick in the cardboard container while it remained negative when the urine remained in the sterile container. These results demonstrate that care needs to be taken when collecting urine samples, and the results of dipstick urinalysis should be used with caution depending on the collection method. PMID:25978475

  2. Calcium in diet

    Science.gov (United States)

    ... best source. Milk and dairy products such as yogurt, cheeses, and buttermilk contain a form of calcium ... the amount of calcium in a dairy product. Yogurt, most cheeses, and buttermilk are excellent sources of ...

  3. Fenoprofen calcium overdose

    Science.gov (United States)

    Fenoprofen calcium is a type of medicine called a nonsteroidal anti-inflammatory drug. It is a prescription pain medicine used to relieve symptoms of arthritis . Fenoprofen calcium overdose occurs when someone takes more than the ...

  4. Calcium channel blocker overdose

    Science.gov (United States)

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

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

    Directory of Open Access Journals (Sweden)

    Carmen Gherasim

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

  7. Calcium and magnesium disorders.

    Science.gov (United States)

    Goff, Jesse P

    2014-07-01

    Hypocalcemia is a clinical disorder that can be life threatening to the cow (milk fever) and predisposes the animal to various other metabolic and infectious disorders. Calcium homeostasis is mediated primarily by parathyroid hormone, which stimulates bone calcium resorption and renal calcium reabsorption. Parathyroid hormone stimulates the production of 1,25-dihydroxyvitamin D to enhance diet calcium absorption. High dietary cation-anion difference interferes with tissue sensitivity to parathyroid hormone. Hypomagnesemia reduces tissue response to parathyroid hormone. PMID:24980727

  8. 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.

  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 cardiop

  10. Average daily nitrate and nitrite intake in the Belgian population older than 15 years

    OpenAIRE

    Temme, Liesbeth; Vandevijvere, Stefanie Marie; Vinkx, Christine; Huybrechts, Inge; Goeyens, Leo; Van Oyen, Herman

    2011-01-01

    Abstract The aim of this study was to assess the dietary intake of nitrate and nitrite in Belgium. The nitrate content of processed vegetables, cheeses and meat products was analyzed. These data were completed by data from non-targeted official control and from literature. In addition, the nitrite content of meat products was measured. Concentration data for nitrate and nitrite were linked to food consumption data of the Belgian Food Consumption Survey. This study included 3245 res...

  11. Regulation by Light of Chemotaxis to Nitrite during the Sexual Life Cycle in Chlamydomonas reinhardtii

    OpenAIRE

    Elena Ermilova; Zhanneta Zalutskaya

    2014-01-01

    Nitrite plays an important role in the nitrogen metabolism of most cells, including Chlamydomonas reinhardtii. We have shown that vegetative cells of C. reinhardtii are attracted by nitrite. The Nia1nit2 mutant with defects in genes encoding the nitrate reductase and regulatory protein NIT2 respectively was found to exhibit normal chemotaxis to nitrite. The data suggest that chemotaxis events appear to be specific and independent of those involved in nitrate assimilation. Unlike vegetative ce...

  12. Modelling the fate of nitrite in an urbanized river using experimentally obtained nitrifier growth parameters

    OpenAIRE

    Raimonet, Mélanie; Vilmin, Lauriane; Flipo, Nicolas; Rocher, Vincent; Laverman, Anniet M

    2015-01-01

    International audience Maintaining low nitrite concentrations in aquatic systems is a major issue for stakeholders due to nitrite's high toxicity for living species. This study reports on a cost-effective and realistic approach to study nitrite dynamics and improve its modelling in human-impacted river systems. The implementation of different nitrifying biomasses to model riverine communities and waste water treatment plant (WWTP)-related communities enabled us to assess the impact of a ma...

  13. Role of the denitrifying Haloarchaea in the treatment of nitrite-brines.

    Science.gov (United States)

    Nájera-Fernández, Cindy; Zafrilla, Basilio; Bonete, María José; Martínez-Espinosa, Rosa María

    2012-09-01

    Haloferax mediterranei is a denitrifying halophilic archaeon able to reduce nitrate and nitrite under oxic and anoxic conditions. In the presence of oxygen, nitrate and nitrite are used as nitrogen sources for growth. Under oxygen scarcity, this haloarchaeon uses both ions as electron acceptors via a denitrification pathway. In the present work, the maximal nitrite concentration tolerated by this organism was determined by studying the growth of H. mediterranei in minimal medium containing 30, 40 and 50 mM nitrite as sole nitrogen source and under initial oxic conditions at 42 degrees C. The results showed the ability of H. mediterranei to withstand nitrite concentrations up to 50 mM. At the beginning of the incubation, nitrate was detected in the medium, probably due to the spontaneous oxidation of nitrite under the initial oxic conditions. The complete removal of nitrite and nitrate was accomplished in most of the tested conditions, except in culture medium containing 50 mM nitrite, suggesting that this concentration compromised the denitrification capacity of the cells. Nitrite and nitrate reductases activities were analyzed at different growth stages of H. mediterranei. In all cases, the activities of the respiratory enzymes were higher than their assimilative counterparts; this was especially the case for NirK. The denitrifying and possibly detoxifying role of this enzyme might explain the high nitrite tolerance of H. mediterranei. This archaeon was also able to remove 60% of the nitrate and 75% of the nitrite initially present in brine samples collected from a wastewater treatment facility. These results suggest that H. mediterranei, and probably other halophilic denitrifying Archaea, are suitable candidates for the bioremediation of brines with high nitrite and nitrate concentrations. PMID:23847815

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

    Science.gov (United States)

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

    2016-08-01

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

  15. Sources of reducing equivalents for nitrite reductase in Pisum arvense roots

    OpenAIRE

    Grażyna Kłobus

    2014-01-01

    Glucose-6-phosphate and NADP+ as well as malic acid and NADP+ present in the incubation mixture enhanced nitrite reductase (EC 1.6.6.4) activity in Pisum arvense roots. This was manifested by a depression of the nitrite level in the tissues and an increased reduction of nitrites by plastids isolated from P. arvense roots. A marked stimulation of plastid malate dehydrogenase was also observed under the influence of nitrates present in the medium. These results suggest that pyridin nucleotides ...

  16. 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

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

    OpenAIRE

    Liliana Avasilcai; Marieta Nichifor; Geanina Bireescu; Rodica Cuciureanu

    2014-01-01

    The aim of the present study was the evaluation of nitrate, nitrite, nitrosodiethylamine (NDEA) and nitrosodimethylamine (NDMA) intake by food consumption. We determined concentrations of nitrates, nitrites in 102 food samples (40 meat products, 15 fermented cheese, 25 vegetables, 22 fruits) and the concentration NDEA, NDMA in 40 meat products. Nitrates and nitrites were determined using Peter-Griess method; nitrosamines were quantified by HPLC with UV detection.  We designed vegetalian, vege...

  18. Portable integrated micro-fluidic platform for the monitoring and detection of nitrite

    OpenAIRE

    Czugala, Monika; Fay, Cormac; O'Connor, Noel E.; Corcoran, Brian; Benito-Lopez, Fernando; Diamond, Dermot

    2013-01-01

    A wireless, portable integrated micro-fluidic platform is proposed and applied for the determination of nitrite anions in water. The colourimetric analysis of nitrite is based on the Griess reagent, and the colour intensity of nitrite Griess reagent complex is detected using a low cost Paired Emitter Detector Diode technique. The micro-fluidic device employed a photoswitchable micro-valve, controlled by white light and generated using a light emitting diode. This low-cost and low-power detect...

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

    Directory of Open Access Journals (Sweden)

    ILIRJANA BOCI

    2014-06-01

    Full Text Available 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 use the smallest possible amount of nitrite as a preservative because nitrite in meat can also form nitrosamines, which can damage the health. That’s why the role of nitrite in processed meat and its recommended level conform to new EC Regulations are given in the introduction part of this paper. It is important that the nitrite level be monitored during all the processing steps up to the end consumers. This makes the objective of this paper. It gives the analytical data on nitrite level on meat processed samples taken and tested during their storage and ripening period of time. Different kinds of meat products are taken and tested to evaluate the influence of various parameters (storage time, time until to the end consumers, various kinds of packing in the degradation rate of ingoing nitrite.

  20. 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.

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

    International Nuclear Information System (INIS)

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

  2. 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.

  3. Model-based evaluation on the conversion ratio of ammonium to nitrite in a nitritation process for ammonium-rich wastewater treatment.

    Science.gov (United States)

    Li, Xiao-Ming; Yang, Qi; Zeng, Guang-Ming; Cornelius, A; Rosenwinkel, K H; Kunst, S; Weichgrebe, D

    2004-01-01

    Modeling for nitritation process was discussed and analyzed quantitatively for the factors that influence nitrite accumulation. The results indicated that pH, inorganic carbon source and Hydraulic Retention Time (HRT) as well as biomass concentration are the main factors that influenced the conversion ratio of ammonium to nitrite. A constant high pH can lead to a high nitritation rate and results in high conversion ratio on condition that free ammonia inhibition do not happen. In a CSTR system, without pH control, this conversion ratio can be monitored by pH variation in the reactor. The pH goes down far from the inlet level means a strongly nitrite accumulation. High concentration of alkalinity can promoted the conversion ratio by means of accelerating the nitritation rate through providing sufficient inorganic carbon source(carbon dioxide). When inorganic carbon source was depleted, the nitritation process stopped. HRT adjustment could be an efficient way to make the nitritation system run more flexible, which to some extent can meet the requirements of the fluctuant of inlet parameters such as ammonium concentration, pH, and temperature and so on. Biomass concentration is the key point, especially for a CSTR system in steady state, which was normally circumscribed by the characteristics of bacteria and may also affected by aeration mode and can be increased by prolonging the HRT on the condition of no nitrate accumulation when no recirculation available. The higher the biomass concentration is, the better the nitrite accumulation can be obtained. PMID:15900739

  4. 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.

  5. Calcium absorption and achlorhydria

    International Nuclear Information System (INIS)

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

  6. EXERCISE ENHANCING CALCIUM ABSORPTION MECHANISM

    OpenAIRE

    Muliani

    2013-01-01

    Calcium has important role in many biological processes therefore calcium homeostasis should be maintained. Imbalance in calcium homeostasis would affects the bone metabolism, neuromuscular function, blood coagulation, cell proliferation and signal transduction. Homeostasis of calcium is maintained by three major organs: gastrointestinal tract, bone and kidney. Intestinal calcium absorption is the sole mechanism to supply calcium to the body. Calcium absorption controlled by calcitropic hormo...

  7. ADSORPTION OF NITRITE FROM AQUEOUS SOLUTION USING SAWDUST

    Directory of Open Access Journals (Sweden)

    Filiz Nuran ACAR

    2002-03-01

    Full Text Available The adsorption of nitrites ions onto sawdust materials have been studied using a batch system. In this study, using adsorbents are beech, pine, poplar and walnut sawdust materials. The maximum adsorption percentage was occured by beech sawdust. In the studies, the effects of adsorbents and the solution of initial pH for beech sawdust were analysed using the first order reversible reaction kinetic model. For the different experimental conditions, the reaction rate constants and equilibrium constant have been determined with this kinetic model.

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

    Science.gov (United States)

    Hvas, Malthe; Damsgaard, Christian; Gam, Le Thi Hong; Huong, Do Thi Thanh; Jensen, Frank B; Bayley, Mark

    2016-07-01

    Striped catfish (Pangasianodon hypophthalmus) are farmed intensively at high stocking densities in Vietnam where they are likely to encounter environmental hypercapnia as well as occasional high levels of aquatic nitrite. Nitrite competes with Cl(-) for uptake at the branchial HCO3(-)/Cl(-) exchanger, causing a drastic reduction in the blood oxygen carrying capacity through the formation of methaemoglobin and nitrosylhaemoglobin. Environmental hypercapnia induces a respiratory acidosis where the branchial HCO3(-)/Cl(-) exchange activity is reduced in order to retain HCO3(-) for pH recovery, which should lead to a reduced nitrite uptake. To assess the effect of hypercapnia on nitrite uptake, fish were cannulated in the dorsal aorta, allowing repeated blood sampling for measurements of haemoglobin derivatives, plasma ions and acid-base status during exposure to 0.9mM nitrite alone and in combination with acute and 48h acclimated hypercapnia over a period of 72h. Nitrite uptake was initially reduced during the hypercapnia-induced acidosis, but after pH recovery the situation was reversed, resulting in higher plasma nitrite concentrations and lower functional haemoglobin levels that eventually caused mortality. This suggests that branchial HCO3(-)/Cl(-) exchange activity is reduced only during the initial acid-base compensation, but subsequently increases with the greater availability of internal HCO3(-) counter-ions as pH is compensated. The data further suggest that branchial Na(+)/H(+) exchange plays a significant role in the initial phase of acid-base compensation. Overall, longer term environmental hypercapnia does not protect against nitrite uptake in P. hypophthalmus, but instead enhances it. In addition, we observed a significant size effect in nitrite accumulation, where large fish attained plasma [nitrite] above the ambient concentration, while small fish did not. Small P. hypophthalmus instead had significantly higher plasma [nitrate], and haemoglobin

  9. Dengue and Calcium

    OpenAIRE

    Shivanthan, Mitrakrishnan C; Rajapakse, Senaka

    2014-01-01

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

  10. Measurements of intracellular calcium

    International Nuclear Information System (INIS)

    Intracellular calcium concentration ([Ca2+]i) has been measured in cultured cells by using Fura-2 load cells and a computer-controlled Perkin Elmer LS-5B spectrofluorometer. Increased [Ca2+]i in cells exposed to extracellular bilirubin was observed both with and without extracellular calcium. However, the increase was considerable larger with extracellular calcium. The enhancement of [Ca2+]i became smaller with decreasing bilirubin/BSA (bovine serum albumine) ratio. 5 refs., 5 figs

  11. Method 353.4 Determination of Nitrate and Nitrite in Estuarine and Coastal Waters by Gas Segmented Continuous Flow Colorimetric Analysis

    Science.gov (United States)

    This method provides a procedure for determining nitrate and nitrite concentrations in estuarine and coastal waters. Nitrate is reduced to nitrite by cadmium,1-3 and the resulting nitrite determined by formation of an azo dye.4-6

  12. Acrylic microspheres-based optosensor for visual detection of nitrite.

    Science.gov (United States)

    Noor, Nur Syarmim Mohamed; Tan, Ling Ling; Heng, Lee Yook; Chong, Kwok Feng; Tajuddin, Saiful Nizam

    2016-09-15

    A new optosensor for visual quantitation of nitrite (NO2(-)) ion has been fabricated by physically immobilizing Safranine O (SO) reagent onto a self-adhesive poly(n-butyl acrylate) [poly(nBA)] microspheres matrix, which was synthesized via facile microemulsion UV lithography technique. Evaluation and optimization of the optical NO2(-) ion sensor was performed with a fiber optic reflectance spectrophotometer. Scanning electron micrograph showed well-shaped and smooth spherical morphology of the poly(nBA) microspheres with a narrow particles size distribution from 0.6 μm up to 1.8 μm. The uniform size distribution of the acrylic microspheres promoted homogeneity of the immobilized SO reagent molecules on the microspheres' surfaces, thereby enhanced the sensing response reproducibility (<5% RSD) with a linear range obtained from 10 to 100 ppm NO2(-) ion. The micro-sized acrylic immobilization matrix demonstrated no significant barrier for diffusion of reactant and product, and served as a good solid state ion transport medium for reflectometric nitrite determination in food samples. PMID:27080889

  13. Enhancing toxic metal removal from acidified sludge with nitrite addition.

    Science.gov (United States)

    Du, Fangzhou; Freguia, Stefano; Yuan, Zhiguo; Keller, Jürg; Pikaar, Ilje

    2015-05-19

    The production of sludge (biosolids) during wastewater treatment is a major issue for water utilities. A main issue limiting its beneficial reuse on agricultural lands is the presence of toxic metals. The currently used metal reduction technologies achieve insufficient removal of metals that are bound to the organic fraction of the sludge. In this study, we propose and demonstrate a novel method that involves the addition of nitrite during sludge acidification to enhance metal removal. Using waste activated sludge collected from three full-scale wastewater treatment plants, we found that acidification to pH 2.0 achieved good Zn solubilization of around 70%, but only 3-7% of Cu was being dissolved. Nitrite addition to the acidified sludge at a concentration of 20 mg NO2(-)-N/L (equals to 19.2 mg HNO2-N/L), substantially enhanced Cu removal to 45-64%, while Zn removal was also increased to over 81%. Metal distribution analysis using sequential chemical extraction revealed that the improvement of Cu and Zn removal was mainly due to the release of the organically bound metal fraction. We hypothesize that free nitrous acid (HNO2, FNA) may assist in the (partial) disruption of extracellular polymeric substances (EPS) and the subsequent release and solubilization of fixed metals. PMID:25872418

  14. Source and sink of nitrite in heavily populated European River

    Science.gov (United States)

    Raimonet, M.; Viollier, E.; Culoma, L.; Laverman, A.

    2012-12-01

    The occurrence of nitrite (NO2-) accumulation is a major environmental issue, as NO2- is highly toxic to living organisms, even at low concentrations. Even if NO2- is generally quickly oxidized in the environment, NO2- accumulation has been reported in various terrestrial and aquatic environments. The Seine River - that receive water effluents from one of the most heavily populated system in Europe - is characterized by NO2- accumulation downstream of Paris city. The main hypotheses to explain the persistence of NO2- are high NO2- concentrations in outlets of the biggest European waste water treatment plant and the low growth rate of nitrifying bacteria - and especially, nitrite oxidizing bacteria - compared to river water residence time. However, the role of benthic processes and sediment resuspension on NO2- dynamics has not been investigated in the river, where fluvial transport generates episodic and frequent resuspension. In this study, we quantified reaction rates of processes involving NO2- production and/or consumption in surface water and sediments, as well as benthic exchanges at the sediment-water interface, under oxic and anoxic conditions. This work allowed estimating the contribution of the Seine River to NO2- dynamics and the response of riverine bacteria to high NO2- loads.

  15. STRESS INDUCED NITROGEN DIFFUSION IN NITRITED CoCr ALLOY

    Directory of Open Access Journals (Sweden)

    AKVILĖ PETRAITIENĖ

    2015-03-01

    Full Text Available In the present study the nitrogen transport mechanism in plasma nitrited CoCr alloy at moderate temperature ( 400ºC is explained by non-Fickian diffusion model. This mechanism is considered by stress induced diffusion model. The model involves diffusion of nitrogen induced by internal stresses created during nitriding process. The model considers the diffusion of nitrogen in the presence of  internal stresses gradient induced by penetrating nitrogen as the next driving force of diffusion after concentration gradient. This model is commonly used for analysis of stainless steel nitriding, however, in this work it is shown that the same nitrogen penetration mechanism takes place in CoCr alloy. For mathematical description of stress induced diffusion process the equation of baro-diffusion is used which involves concentration dependant baro-diffusion concentration. For calculation of stress gradient it is assumed that stress depth profile linearly relates with nitrogen concentration depth profile. The fitting is done using experimental curves of nitrogen depth profiles for medical grade CoCr alloy (ISO 5831-12 nitrited at 400 ºC temperature. The experimental curves are taken from literature. The nitriding duration was 2h, 6h, 20h. Calculated nitrogen depth profiles in CoCr alloy are in good agreement with experimental nitrogen depth profiles.  The diffusion coefficient D is found from fitting of experimental data.DOI: http://dx.doi.org/10.5755/j01.ms.21.1.5711

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

    Science.gov (United States)

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

    2015-12-30

    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 NO2(-) 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 NO2(-), respectively. The residual NO2(-) was less than 0.5mg/L in the reactor containing added NO2(-), 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. PMID:26266896

  17. Raman scattering in sodium nitrite crystals near the phase transition

    Science.gov (United States)

    Gorelik, V. S.; Pyatyshev, A. Yu.; Krylov, A. S.

    2016-01-01

    Optical Raman spectra of a ferroelectric sodium nitrite crystal have been detected in a wide spectrum range at various temperatures, including the region of the ferroelectric phase transition. A manifestation of a transverse soft polar mode of the A 1( z) type responsible for the ferroelectric phase transition has been discovered in the spectrum at room temperature. This mode has been found to become overdamped even far from the ferroelectric phase transition temperature. This mode also appears as a central peak under heating. It has been found that the pseudoscalar mode of the A 2 type has the highest intensity in the Raman spectrum of sodium nitrite. The frequency corresponding to the maximum intensity of this mode in the Raman spectrum varies from 130 cm-1 at 123 K to 106 cm-1 at T = 513 K. A fair agreement of the experimental data for the A 1( z) mode with the Lyddane-Sachs-Teller relation has been established. The polariton curves for the A 1( z) polar mode and the dispersion curves for axinons has been plotted.

  18. Sugar-Driven Prebiotic Synthesis of Ammonia from Nitrite

    Science.gov (United States)

    Weber, Arthur L.

    2010-03-01

    Reaction of 3-5 carbon sugars, glycolaldehyde, and α-ketoaldehydes with nitrite under mild anaerobic aqueous conditions yielded ammonia, an essential substrate for the synthesis of nitrogen-containing molecules during abiogenesis. Under the same conditions, ammonia synthesis was not driven by formaldehyde, glyoxylate, 2-deoxyribose, and glucose, a result indicating that the reduction process requires an organic reductant containing either an accessible α-hydroxycarbonyl group or an α-dicarbonyl group. Small amounts of aqueous Fe+3 catalyzed the sugar-driven synthesis of ammonia. The glyceraldehyde concentration dependence of ammonia synthesis, and control studies of ammonia’s reaction with glyceraldehyde, indicated that ammonia formation is accompanied by incorporation of part of the synthesized ammonia into sugar-derived organic products. The ability of sugars to drive the synthesis of ammonia is considered important to abiogenesis because it provides a way to generate photochemically unstable ammonia at sites of sugar-based origin-of-life processes from nitrite, a plausible prebiotic nitrogen species.

  19. Biological nitrogen removal in one step by nitritation and anaerobic oxidation of ammonia in biofilms; Einstufige biologische Stickstoffelimination durch Nitritation und anaerobe Ammonium-Oxidation im Biofilm

    Energy Technology Data Exchange (ETDEWEB)

    Helmer, C.; Tromm, C.; Hippen, A.; Rosenwinkel, K.H.; Seyfried, C.F.; Kunst, S. [Hannover Univ. (Germany). Inst. fuer Siedlungswasserwirtschaft und Abfalltechnik

    1999-07-01

    For biological treatment of high nitrogenous wastewaters with low C/N ratio autotrophic microorganisms which are able to convert ammonium directly into nitrogen gas are especially interesting. It is exceptionally difficult to verify their presence and importance in mixed populations of full scale wastewater treatment plants. So it could not be clarified finally up to now which basic microbial reactions lead to single stage complete nitrogen removal, here called deammonification, in the nitrification step (biological contactor) of the leachate treatment plant in Mechernich. It succeeded meanwhile to establish the process of deammonification in a continuous flow moving-bed pilot plant. In batch experiments which biomass-covered carriers nitrogen conversions could become investigated at the intact biofilm for the first time. Two autotrophic nitrogen conversion reactions could be proved in the biofilm depending on dissolved oxygen (DO) concentration: A nitritation under aerobic conditions and an anaerobic ammonium oxidation. For the anaerobic ammonium oxidation nitrite was used as electron acceptor with ammonium as electron donor. N{sub 2} was the end product of the reaction. The ratio of ammonium conversion to nitrite conversion was 1:1,37, which was described in the same range for the ANAMMOX-process (1:1,31{+-}0,06). Nitrate could not be used as electron acceptor. Nitrite had to be added to the experiment to obtain oxygen independent oxidation of ammonium. The parts of nitritation and anaerobic ammonium conversion in nitrogen conversion could be controlled by the DO concentration. At a DO concentration of 0.7 mg/l both processes were balanced, so that a direct almost complete elimination of ammonium was possible without any dosage of nitrite. The added ammonium was partially oxidised to nitrite and partially oxidised anaerobically. The aerobic ammonium oxidation to nitrite in the outer oxygen supplied biofilm layers produced the reactant for the anaerobic ammonium

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

    Directory of Open Access Journals (Sweden)

    Dalia A. Zahran

    2011-10-01

    Full Text Available Nitrite, a curing agent of meat products, is a precursor of carcinogenic N-nitrosamines during processing of meat products or under human stomach conditions, as well as having its own toxicity. To investigate the residual nitrite level in meat products marketed in Egyptian markets, 160 samples of cured cooked (luncheon and frankfurter and cured raw (oriental sausages and pastirma meat products (40 sample each were analyzed for residual nitrite by a spectrophotometric method. Samples were subjected to irradiation (3.0 and 5.0 kGy by electron beam accelerator to evaluate its effect on the residual nitrite level in the examined cured meat products. For statistical analysis, means and standard errors of residual nitrite level were determined and analyzed by one-way analysis of variance. The results revealed that the residual nitrite level was ranging between 10.45-251.6 ppm in the examined meat products and that pastirma had the highest residual level (p<0.05 while luncheon showed the least level. Residual nitrite level was significantly reduced (p<0.05 by electron beam irradiation (5.0 kGy and the reduction was dose dependent. This demonstrated that it would still be important to strengthen on control of residual nitrite level in Egyptian meat products and food safety education for public people.

  1. Properties of reformulated hot dog sausage without added nitrites during chilled storage.

    Science.gov (United States)

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

    2016-01-01

    The aim of this study was to assess the effect of a complete nitrite replacement strategy using celery, carmine, sodium lactate and orange dietary fibre combined with vitamins C and E, on the quality characteristics (technological, sensorial and safety properties) of hot dog sausages (five samples) during chilled storage (2 ± 1℃ 60 days). Nitrite replacers (combined with vitamins C and E) presented antioxidant activity, reducing lipid oxidation in reformulated samples. At the end of storage redness (a*) was similar in the control sample (with added nitrite) and in the sample without added nitrite. Sensory evaluation detected no significant difference between samples with and without added nitrite. All the reformulated samples were judged acceptable by the panellists. At the end of storage, the control sample contained more than four times as much residual nitrite as the reformulated samples. Growth of presumptive Clostridium perfringens was not observed in any of the samples. Samples without added nitrite had longer shelf-lives than control sausage. Samples containing 0.1% vitamin C registered the lowest microbiological levels. This strategy could be a good alternative to reduce and/or eliminate added nitrite in hot dog sausages. PMID:25480689

  2. 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 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.

    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. Susceptibility of Nile tilapia (Oreochromis niloticus) fed dietary sodium chloride to nitrite toxicity

    Science.gov (United States)

    Juvenile Nile tilapia (Oreochromis niloticus) were fed diets supplemented with 0 or 6% NaCl for 10 weeks. Tilapia were exposed to approximately 21 mg/l nitrite-N after five and ten weeks of feeding to determine the effect of dietary NaCl supplementation on resistance to nitrite toxicity. Fish were...

  5. 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...

  6. 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 (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES Specific Administrative Rulings and Decisions § 170.60 Nitrites and/or nitrates...

  7. Low-dose sodium nitrite vasodilates hypoxic human pulmonary vasculature by a means that is not dependent on a simultaneous elevation in plasma nitrite

    OpenAIRE

    Ingram, Thomas E.; Pinder, Andrew G.; Bailey, Damian M; Fraser, Alan G.; James, Philip E.

    2009-01-01

    Inorganic nitrite has recently been recognized to possess vascular activity that is enhanced in hypoxia. This has been demonstrated in humans in the forearm vascular bed. In animal models nitrite reduces pulmonary vascular resistance, but its effects upon the pulmonary circulation of humans have not yet been demonstrated. This paradigm is of particular interest mechanistically since the pulmonary vasculature is known to behave differently to the systemic. To investigate, 18 healthy volunteers...

  8. Formation of new bioactive organic nitrites and their identification with gas chromatography-mass spectrometry and liquid chromatography coupled to nitrite reduction.

    OpenAIRE

    Nilsson, Kristofer F.; Lundgren, Michael; Agvald, Per; Adding, L. Christofer; Linnarsson, Dag; Lars E Gustafsson

    2011-01-01

    Abstract Nitric oxide (NO) donors, notably organic nitrates and nitrites are used therapeutically but tolerance develops rapidly, making the use of e.g. nitroglycerin difficult. NO donation in the pulmonary vascular bed might be useful in critically ill patients. Organic nitrites are not associated with tachyphylaxis but may induce methaemoglobinemia and systemic hypotension which might hamper their use. We hypothesised that new lung-selective NO donors can be identified by utilizi...

  9. 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.

    Science.gov (United States)

    Jensen, Frank B; Gerber, Lucie; Hansen, Marie N; Madsen, Steffen S

    2015-07-01

    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-nitrosated compounds. Nitrite uptake was slightly higher in hypoxia than normoxia, and high internal nitrite levels extensively converted blood hemoglobin to methemoglobin and nitrosylhemoglobin. Hypoxia increased inducible NOS (iNOS) mRNA levels in the gills, which was overruled by a strong inhibition of iNOS expression by nitrite in both normoxia and hypoxia, suggesting negative-feedback regulation of iNOS gene expression by nitrite. A similar inhibition was absent for neuronal NOS. Branchial NKA activity stayed unchanged, but mRNA levels of the nkaα1a subunit increased with hypoxia and nitrite, which may have countered an initial NKA inhibition. Nitrite also increased hsp70 gene expression, probably contributing to the cytoprotective effects of nitrite at low concentrations. Nitrite displays a concentration-dependent switch between positive and negative effects similar to other signaling molecules. PMID:25908056

  10. Measurements of nitrite production and nitrite-producing organisms in and around the primary nitrite maximum in the central California Current

    Directory of Open Access Journals (Sweden)

    A. E. Santoro

    2013-03-01

    Full Text Available Nitrite (NO2– is a substrate for both oxidative and reductive microbial metabolism. NO2– accumulates at the base of the euphotic zone in oxygenated, stratified open ocean water columns, forming a feature known as the primary nitrite maximum (PNM. Potential pathways of NO2– production include the oxidation of ammonia (NH3 by ammonia-oxidizing bacteria or archaea and assimilatory nitrate (NO3– reduction by phytoplankton or heterotrophic bacteria. Measurements of NH3 oxidation and NO3– reduction to NO2– were conducted at two stations in the central California Current in the eastern North Pacific to determine the relative contributions of these processes to NO2– production in the PNM. Sensitive (−1, high-resolution measurements of [NH4+] and [NO2–] indicated a persistent NH4+ maximum overlying the PNM at every station, with concentrations as high as 1.5 μmol L−1. Within and just below the PNM, NH3 oxidation was the dominant NO2– producing process with rates of NH3 oxidation of up to 50 nmol L−1 d−1, coinciding with high abundances of ammonia-oxidizing archaea. Though little NO2– production from NO3– was detected, potentially nitrate-reducing phytoplankton (photosynthetic picoeukaryotes, Synechococcus, and Prochlorococcus were present at the depth of the PNM. Rates of NO2– production from NO3– were highest within the upper mixed layer (4.6 nmol L−1 d−1 but were either below detection limits or 10 times lower than NH3 oxidation rates around the PNM. One-dimensional modeling of water column NO2– profiles supported direct rate measurements of a net biological sink for NO2– just below the PNM. Residence time estimates of NO2– within the PNM were similar at the mesotrophic and oligotrophic stations and ranged from 150–205 d. Our results suggest the PNM is a dynamic, rather than relict, feature with a source term dominated by ammonia oxidation.

  11. Biochemical predetermination of the NO synthase and nitrite reductase components of the nitric oxide cycle.

    Science.gov (United States)

    Reutov, V P

    1999-05-01

    This review presents some aspects of a concept of cellular evolution bearing a relationship to nitrate--nitrite respiration, the endosymbiosis theory, and the origin of NO synthase and nitrite reductase activity in heme-containing proteins. Analysis of structural and functional unity of the NO synthase and nitrite reductase systems suggests that these systems did not arise without any relation to evolutionarily ancient energetic systems of cells. The use of symmetry principles reveals commonalities among many electron transport chains which in the language of physics is called "invariance". This work also comparatively analyzes the nitric oxide cycle and the known nitrogen cycle. The ideas about evolution of the NO synthase and nitrite reductase systems developed here are clearly compatible with the endosymbiotic theory and the hypothesis that nitrate--nitrite respiration was a precursor of oxygen-dependent respiration. PMID:10381613

  12. Achieving and maintaining biological nitrogen removal via nitrite under normal conditions

    Institute of Scientific and Technical Information of China (English)

    CUI You-wei; PENG Yong-zhen; GAN Xiang-qing; YE Liu; WANG Ya-yi

    2005-01-01

    The principal aim of this paper is to develop an approach to realize stable biological nitrogen removal via nitrite under normal conditions. Validation of the new method was established on laboratory-scale experiments applying the sequencing batch reactor(SBR)activated sludge process to domestic wastewater with low C/N ratio. The addition of sodium chloride(NaCl) to influent was established to achieve nitrite build-up. The high nitrite accumulation, depending on the salinity in influent and the application duration of salt, was obtained in SBRs treating saline wastewater. The maintenance results indicated that the real-time SBRs can maintain stable nitrite accumulation, but conversion from shorter nitrification-denitrification to full nitrification-denitrification was observed after some operation cycles in the other SBR with fixed-time control. The presented method is valuable to offer a solution to realize and to maintain nitrogen removal via nitrite under normal conditions.

  13. Effect of anaerobic digestion on the high rate of nitritation, treating piggery wastewater

    Institute of Scientific and Technical Information of China (English)

    Jiyeol Im; Kyungik Gil

    2011-01-01

    The amount of piggery wastewater as domestic livestock is increasing.The volume of piggery wastewater produced is less than the volume of other wastewaters,but piggery wastewater has a heavy impact on wastewater streams due to an extremely high concentration of nitrogen and COD.In this study,laboratory reactors were operated using piggery wastewater and the effluent of anaerobic digester from piggery wastewater plants.The purpose of this study was to induce the nitritation process,which is an economically advantageous nitrogen removal method that converts ammonium nitrogen into nitrite.The results showed that the effluent of anaerobic digester from piggery wastewater was more efficient than raw piggery wastewater in terms of inducing nitritation.It can be deduced that nitritation is largely affected by an organic fraction of piggery wastewater.It can also be concluded that a small amount of biodegradable organic matter in piggery wastewater is efficient in inducing nitritation.

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

    DEFF Research Database (Denmark)

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

    2008-01-01

    In 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...... 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...

  15. 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

    Aerobic ammonium-oxidizing bacteria (AerAOB) and anoxic ammonium-oxidizing bacteria (AnAOB) cooperate in partial nitritation/anammox systems to remove ammonium from wastewater. In this process, large granular microbial aggregates enhance the performance, but little is known about granulation so far......AOB 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...

  16. Progressive effects of the interaction of Sodium nitrite and sunset yellow on different physiological parameters in albino rats

    Directory of Open Access Journals (Sweden)

    Eman. G.E. Helal

    2001-06-01

    Full Text Available It has been noticed that the Egyptian children usually eat and drink food containing both food preservative and food colourants at the same time . This has attracted the attention to study the interaction between one of food preservatives (sodium nitrite and a food coloring agent (sunset yellow. The mixture of the two agents at the limited dose of each was found to be a lethal dose. So, 1/10th of this dose was used daily for 30 days. Animals were devided into three groups. The first group served as a control, while the second group was orally administered a mixture of 10mg sod. nitrite (NaNO3/kg and 0.5 mg/ kg /day sun set yellow (S.S.Y/. The third group received selenium (5 mcg/kg in addition to the above mentioned mixture. After 30 days of treatment, half of the animals from each group were decapitated. The other half of animals was left for another 15 days without treatment for recovery. Ingestion of the mixture of (NaNO3 and S.S.Y significantly decreased rat body weight, R B C and WBC counts, Hb %. , Hct %. Serum inorganic phosphorus, serum protein and serum albumin. Significant increases were observed in serum glucose, T3, T4, calcium, GGT, LDH, Cpk, ALK.ph and cholesterol. Also cholesterol of brain, liver and heart were significantly elevated. No changes were recorded for organ/ body weight, respiratory rate, heart beats, rectal temperature, AST and ALT activities of serum and tissues, acid phosphatase activity, total lipids of serum and tissues, cholesterol of muscle and kidney and serum triglycerides A complete recovery from the abnormalities of most biochemical and haematological parameters was observed after 15 days recovery or when selenium was administered This draws attention to the dangers of interactions of such preservatives and colorants. The present study showed that even the permitted doses of colourants and food preservatives may be harmful.

  17. 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...

  18. Conjugated linoleic acid and nitrite attenuate mitochondrial dysfunction during myocardial ischemia.

    Science.gov (United States)

    Van Hoose, Patrick M; Kelm, Natia Qipshidze; Piell, Kellianne M; Cole, Marsha P

    2016-08-01

    Cardiovascular health is influenced by dietary composition and the western diet is composed of varying types/amounts of fat. Conjugated linoleic acid (cLA) is an abundant dietary unsaturated fatty acid associated with health benefits but its biological signaling is not well understood. Nitrite is enriched in vegetables within the diet and can impact signaling of unsaturated fatty acids; however, its role on cLA signaling is not well understood. Elucidating how nitrite may impact the biological signaling of cLA is important due to the dietary consumption of both cLA and nitrite in the western diet. Since co-administration of cLA and nitrite results in cardioprotection during myocardial infarction (MI), it was hypothesized that cLA and nitrite may affect cardiac mitochondrial respiratory function and complex activity in MI. C57BL/6J mice were treated with cLA and nitrite for either 10 or 13days, where MI was induced on day 3. Following treatment, respiration and complex activity were measured. Among the major findings of this study, cLA treatment (10days) decreases state 3 respiration in vivo. Following MI, nitrite alone and in combination with cLA attenuates increased state 3 respiration and decreases hydrogen peroxide levels. Further, nitrite and cLA co-treatment attenuates increased complex III activity after MI. These results suggest that cLA, nitrite and the combination significantly alter cardiac mitochondrial respiratory and electron transport chain activity in vivo and following MI. Overall, the daily consumption of cLA and nitrite in the diet can have diverse cardiovascular implications, some of which occur at the mitochondrial level. PMID:27156147

  19. 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. PMID:23033643

  20. Antimicrobial effect of acidified nitrate and nitrite on six common oral pathogens in vitro

    Institute of Scientific and Technical Information of China (English)

    XIA Deng-sheng; LIU Yin; ZHANG Chun-mei; YANG Sheng-hui; WANG Song-lin

    2006-01-01

    Background Salivary nitrate is positively correlated with plasma nitrate and its level is 9 times the plasma level after nitrate loading. Nitrate in saliva is known to be reduced to nitrite by oral bacteria. Nitrate and nitrite levels in saliva are 3-5 times those in serum in physiological conditions respectively in our previous study. The biological functions of high salivary nitrate and nitrite are still not well understood. The aim of this in vitro study was to investigate the antimicrobial effects of nitrate and nitrite on main oral pathogens under acidic conditions.Methods Six common oral pathogens including Streptococcus mutans NCTC 10449, Lactobacillus acidophilus ATCC 4646, Porphyromonas gingivalis ATCC 33277, Capnocytophaga gingivalis ATCC 33624, Fusobacterium nucleatum ATCC 10953, and Candida albicans ATCC 10231 were cultured in liquid medium. Sodium nitrate or sodium nitrite was added to the medium to final concentrations of 0, 0.5, 1, 2, and 10 mmol/L. All of the microorganisms were incubated for 24 to 48 hours. The optical densities (OD) of cell suspensions were determined and the cultures were transferred to solid nutrient broth medium to observe the minimum inhibitory concentration and minimum bactericidal/fungicidal concentration for the six tested pathogens.Results Nitrite at concentrations of 0.5 to 10 mmol/L had an inhibitory effect on all tested organisms at low pH values. The antimicrobial effect of nitrite increased with the acidity of the medium. Streptococcus mutans NCTC 10449 was highly sensitive to nitrite at low pH values. Lactobacillus acidophilus ATCC 4646 and Candida albicans ATCC 10231 were relatively resistant to acidified nitrite. Nitrate at the given concentrations and under acidic conditions had no inhibitory effect on the growth of any of the tested pathogens.Conclusion Nitrite, at a concentration equal to that in human saliva, is both cytocidal and cytostatic to six principal oral pathogens in vitro, whereas nitrate at a similar

  1. Serum Calcium Level in Hypertension

    OpenAIRE

    Hazari, Mohammed Abdul Hannan; Arifuddin, Mehnaaz Sameera; Muzzakar, Syed; Reddy, Vontela Devender

    2012-01-01

    Background: The alterations in extracellular calcium level may influence intracellular calcium level and possibly play a role in the pathogenesis of essential hypertension. Aim: The purpose was to find out the association between serum calcium levels and hypertension; and to compare the serum calcium levels between normotensive controls, hypertensive subjects on calcium channel blockers, and hypertensive subjects on antihypertensive medication other than calcium channel blockers. Materials an...

  2. 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 expos

  3. 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 calciu

  4. Strategies of Nitrosomonas europaea 19718 to counter low dissolved oxygen and high nitrite concentrations

    Directory of Open Access Journals (Sweden)

    Chandran Kartik

    2010-03-01

    Full Text Available Abstract Background Nitrosomonas europaea is a widely studied chemolithoautotrophic ammonia oxidizing bacterium. While significant work exists on the ammonia oxidation pathway of N. europaea, its responses to factors such as dissolved oxygen limitation or sufficiency or exposure to high nitrite concentrations, particularly at the functional gene transcription level are relatively sparse. The principal goal of this study was to investigate responses at the whole-cell activity and gene transcript levels in N. europaea 19718 batch cultures, which were cultivated at different dissolved oxygen and nitrite concentrations. Transcription of genes coding for principal metabolic pathways including ammonia oxidation (amoA, hydroxylamine oxidation (hao, nitrite reduction (nirK and nitric oxide reduction (norB were quantitatively measured during batch growth, at a range of DO concentrations (0.5, 1.5 and 3.0 mg O2/L. Measurements were also conducted during growth at 1.5 mg O2/L in the presence of 280 mg-N/L of externally added nitrite. Results Several wide ranging responses to DO limitation and nitrite toxicity were observed in N. europaea batch cultures. In contrast to our initial hypothesis, exponential phase mRNA concentrations of both amoA and hao increased with decreasing DO concentrations, suggesting a mechanism to metabolize ammonia and hydroxylamine more effectively under DO limitation. Batch growth in the presence of 280 mg nitrite-N/L resulted in elevated exponential phase nirK and norB mRNA concentrations, potentially to promote utilization of nitrite as an electron acceptor and to detoxify nitrite. This response was in keeping with our initial hypothesis and congruent with similar responses in heterotrophic denitrifying bacteria. Stationary phase responses were distinct from exponential phase responses in most cases, suggesting a strong impact of ammonia availability and metabolism on responses to DO limitation and nitrite toxicity. In general

  5. Inhibition of hypochlorous acid-induced cellular toxicity by nitrite

    Science.gov (United States)

    Whiteman, Matthew; Hooper, D. Craig; Scott, Gwen S.; Koprowski, Hilary; Halliwell, Barry

    2002-09-01

    Chronic inflammation results in increased nitrogen monoxide (NO) formation and the accumulation of nitrite (NO). Neutrophils stimulated by various inflammatory mediators release myeloperoxidase to produce the cytotoxic agent hypochlorous acid (HOCl). Exposure of chondrocytic SW1353 cells to HOCl resulted in a concentration- and time-dependent loss in viability, ATP, and glutathione levels. Treatment of cells with NO but not nitrate (NO) substantially decreased HOCl-dependent cellular toxicity even when NO was added at low (μM) concentrations. In contrast, NO alone (even at 1 mM concentrations) did not affect cell viability or ATP and glutathione levels. These data suggest that NO accumulation at chronic inflammatory sites, where both HOCl and NO are overproduced, may be cytoprotective against damage caused by HOCl. We propose that this is because HOCl is removed by reacting with NO to give nitryl chloride (NO2Cl), which is less damaging in our cell system. inflammation | cell toxicity | nitryl chloride | nitric oxide | arthritis

  6. Blood indexes of nitrite toxicosis in dairy cows

    Directory of Open Access Journals (Sweden)

    B. Stefanon

    2011-03-01

    Full Text Available Nitrate (NO_ 3 and nitrite (NO_ 2 can be ingested with water and feeds and NO_ 2 can be produced from NO_ 3 by rumen and intestinal microbes. Moreover,NO_ 3 and NO_ 2 are endogenously produced by cells of various tissues from nitric oxide (NO and arginine (Passi, 2000. Toxicity of NO_ 3 is casued by the reduction to NO_ 2 in the rumen environment. This ion competes with superoxide for hemoglobin (Doyle et al., 1982, producing methemoglobin (MtHb, which does not carry oxygen. The reaction is reversible, but the transient hypoxia can be exacerbated if the amount of ingested nitrates is high, causing fall of blood pressure and increase of heart rate........

  7. 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.

  8. Seasonal Cycle Analysis of the Nitrate Nitrogen and Nitrite Nitrogen in the Bohai Sea

    Institute of Scientific and Technical Information of China (English)

    Shi Qiang; Chen Jianglin; Li Chongde

    2002-01-01

    During 1985~1987, the concentration of nitrate nitrogen was higher in the Laizhou Bay and the Bohai Bay while that of nitrite nitrogen was higher in the Liaodong Bay and the Bohai Bay. The concentration of nitrate nitrogen was highest in winter and lowest in summer while that of nitrite nitrogen was highest in autumn and lowest in spring. The seasonal variation of the concentration of nitrate nitrogen was maximum in the Laizhou Bay and the Bohai Bay while that of the concentration of nitrite nitrogen was maximum in the Liaodong Bay. There was a great difference in the concentration of nitrate nitrogen between the surface and the bottom in autumn and in the concentration of nitrite nitrogen between the surface and the bottom in summer. The main reason for the seasonal variations of the concentration of nitrate nitrogen and nitrite nitrogen was the marine biochemical process. The nitrate nitrogen and nitrite nitrogen in the Bohai Sea basically maintained a quasi-equilibrium state seasonal cycle. The quasi-equilibrium state seasonal cycle of nitrate nitrogen and nitrite nitrogen at the bottom was stable while that at the surface was liable to variations caused by other factors.

  9. Coastal water column ammonium and nitrite oxidation are decoupled in summer

    Science.gov (United States)

    Heiss, Elise M.; Fulweiler, Robinson W.

    2016-09-01

    Water column nitrification is a key process in the nitrogen cycle as it links reduced and oxidized forms of nitrogen and also provides the substrate (nitrate) needed for reactive nitrogen removal by denitrification. We measured potential water column ammonium and nitrite oxidation rates at four sites along an estuary to continental shelf gradient over two summers. In most cases, nitrite oxidation rates outpaced ammonium oxidation rates. Overall, ammonium and nitrite oxidation rates were higher outside of the estuary, and this trend was primarily driven by higher oxidation rates in deeper waters. Additionally, both ammonium and nitrite oxidation rates were impacted by different in situ variables. Ammonium oxidation rates throughout the water column as a whole were most positively correlated to depth and salinity and negatively correlated to dissolved oxygen and light. In contrast, nitrite oxidation rates throughout the water column were negatively correlated with light and pH. Multivariate regression analysis revealed that while both surface (20 m) ammonium oxidation rates were most strongly predicted by depth and light, surface rates were also regulated by salinity and deep rates by temperature. Surface (pH) alone, while salinity, [H+], temperature, and depth all played a role in predicting deep (>20 m) nitrite oxidation rates. These results support the growing body of evidence that ammonium oxidation and nitrite oxidation are not always coupled, should be measured separately, and are influenced by different environmental conditions.

  10. Nitrous oxide formation during nitritation and nitrification of high-strength wastewater.

    Science.gov (United States)

    Schneider, Yvonne; Beier, Maike; Rosenwinkel, Karl-Heinz

    2013-01-01

    The purpose of this study was to investigate the formation of nitrous oxide (N2O) in nitritation and nitrification under stable, comparable and not limiting conditions typical for treatment of high-strength wastewater. A laboratory-scale aerated chemostat was operated with reject water at different sludge retention times, achieving suppression of nitrate formation by wash-out of nitrite-oxidizing bacteria for nitritation. The N2O formation factor during stable nitritation was higher (2.90% N2O-N /NH4(-)-Nox) than during nitrification (0.74%). The positive correlation of N2O formation rates and ammonium oxidation rates was linear and thus did not contribute to changes of the N2O formation factor. The dominant factor for N2O formation during stable operation was high nitrite concentration, which was positively correlated with N2O formation rates. The highest formation factors were observed during a transition phase from nitrification to nitritation with unstable process conditions (4.81%) and during a short-term experiment with increased pH of 7 (10.28%). The results indicate that even with operational conditions that are regarded favourable for the process of nitritation N2O formation can be limited but not avoided. PMID:23752381

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

    Science.gov (United States)

    Lefevre, Sjannie; Jensen, Frank B; Huong, Do T T; Wang, Tobias; Phuong, Nguyen T; Bayley, Mark

    2012-08-15

    The tolerance and effects of nitrite on ion balance and haematology were investigated in the striped snakehead, Channa striata Bloch 1793, which is an air-breathing fish with reduced gills of importance for aquaculture in South East Asia. C. striata was nitrite tolerant with a 96 h LC50 of 4.7 mM. Effects of sub-lethal exposures to nitrite (0mM, 1.4mM, and 3.0mM) 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 150 mM to 120 mM, while plasma chloride fell from 105 mM to 60mM and plasma bicarbonate rose from 12 mM in controls to 20mM in exposed fish. The extreme changes in ion balance in C. striata are different from the response reported in other fish, and further studies are needed to investigate the mechanism behind the observed changes in regulation. PMID:22516674

  12. Nitrite dynamics and associated feedback processes in the Benguela oxygen minimum zone

    Science.gov (United States)

    Mashifane, Thulwaneng; Waldron, Howard; Vichi, Marcello

    2016-04-01

    Understanding nitrite dynamics in the Benguela oxygen minimum zone (OMZ) is a challenge as it represents an intermediary nitrogen species with a short turnover time. Nitrite is also reduced to nitrogen in some OMZs, preventing its accumulation. This creates difficulties in detecting nitrite with colorimetric methods as concentrations occur below the detection limit in some regions. Nitrite concentrations are key to understanding dominant nitrogen loss mechanisms through modeling studies in the Benguela OMZ. The coupled physical-biogeochemical model for eastern boundary upwelling systems (BioEBUS) using the Southern Africa experiment (SAfE) nested configuration is applied in the Benguela to study nitrite dynamics. Model results show nitrite maxima associated with the Angola-Benguela front region. The maxima are linked to poleward nutrient rich, oxygen-depleted south Atlantic central water (SACW) from the Angola gyre which favour denitrification on the shelf during summer to autumn. Ventilation of the shelf during winter to spring by the equatorward well-aerated eastern south Atlantic central water (ESACW) results in depleted nitrite concentrations. In addition to local circulation, Hovmuller analyses suggest that both primary and secondary nitrite maxima are driven by shelf biogeochemical processes and offshore advection. Vertical depth profiles show nitrite maxima at 17°S and depletion at 23°S attributed to denitrification and anammox, respectively. Model results suggest nitrogen in the Benguela OMZ is lost to anammox, denitrification and offshore advection, with denitrification as the dominant loss mechanism rather than anammox as previously documented. These results are key to understanding feedback processes from nitrogen loss in the Benguela OMZ and its impact on related biogeochemical cycles.

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

    OpenAIRE

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

    2015-01-01

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

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

    International Nuclear Information System (INIS)

    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. Neuronal calcium sparks and intracellular calcium “noise”

    OpenAIRE

    Melamed-Book, Naomi; Kachalsky, Sylvia G.; Kaiserman, Igor; Rahamimoff, Rami

    1999-01-01

    Intracellular calcium ions are involved in many forms of cellular function. To accommodate so many control functions, a complex spatiotemporal organization of calcium signaling has developed. In both excitable and nonexcitable cells, calcium signaling was found to fluctuate. Sudden localized increases in the intracellular calcium concentration—or calcium sparks—were found in heart, striated and smooth muscle, Xenopus Laevis oocytes, and HeLa and P12 cells. In the nervous system, intracellular...

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

    International Nuclear Information System (INIS)

    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 μM-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.

  18. 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.

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

    Directory of Open Access Journals (Sweden)

    Alejandro Rodriguez-Sanchez

    2014-06-01

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

  20. Calcium addition in straw gasification

    DEFF Research Database (Denmark)

    Risnes, H.; Fjellerup, Jan Søren; Henriksen, Ulrik Birk;

    2003-01-01

    The present work focuses on the influence of calcium addition in gasification. The inorganic¿organic element interaction as well as the detailed inorganic¿inorganic elements interaction has been studied. The effect of calcium addition as calcium sugar/molasses solutions to straw significantly...... affected the ash chemistry and the ash sintering tendency but much less the char reactivity. Thermo balance test are made and high-temperature X-ray diffraction measurements are performed, the experimental results indicate that with calcium addition major inorganic¿inorganic reactions take place very late...... calcium binds silicon primarily as calcium silicates and less as potassium calcium silicates....

  1. Calcium binding by dietary fibre

    International Nuclear Information System (INIS)

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

  2. [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 ab

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

    DEFF Research Database (Denmark)

    Koch, Hanna; Lücker, Sebastian; Albertsen, Mads; Kitzinger, Katharina; Herbold, Craig; Spieck, Eva; Nielsen, Per Halkjær; Wagner, Michael; Daims, Holger

    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...... oxidizers lacking urease with ammonia from urea, which is fully nitrified by this consortium through reciprocal feeding. The presence of highly similar urease genes in Nitrospira lenta from activated sludge, in metagenomes from soils and freshwater habitats, and of other ureases in marine nitrite oxidizers......, suggests a wide distribution of this extended interaction between ammonia and nitrite oxidizers, which enables nitrite-oxidizing bacteria to indirectly use urea as a source of energy. A soluble formate dehydrogenase lends additional ecophysiological flexibility and allows N. moscoviensis to use formate...

  4. Nitrate and nitrite levels of potable water supply in Warri, Nigeria: a public health concern.

    Science.gov (United States)

    Nduka, John Kanayochukwu; Orisakwe, Orish Ebere; Ezenweke, Linus Obi

    2010-01-01

    In this study, the authors investigated the nitrate and nitrite in different water sources (surface water, shallow well water, and borehole water) in the market and industrialized areas of Warri in the Niger Delta area of Nigeria. The authors' goal was to find the comparative levels of nitrates and nitrites from these two parts of the community. They selected five sampling sites from industrialized areas and another five from market areas. Nitrate and nitrites were determined using a DR/4000 UV-Vis spectrophotometer. The appreciable quantities of nitrates and nitrites found in these investigations have some public health implications. This study suggests that indiscriminate disposal of waste and poor sanitation may be additional contributing factors in the nitrate pollution of the water supply in the Niger Delta area of Nigeria. PMID:20104831

  5. 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.

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

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    Nitrate and nitrite contamination of surface waters (e.g. lakes) has become a severe environmental and health problem, especially in developing countries. The recent demonstration of nitrate reduction at the cathode of microbial fuel cell (MFC) provides an opportunity to develop a new technology...... 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 with biocathode, compared to either the open-circuit operation or with abiotic cathode. The mass balance on nitrogen indicates that most of the removed nitrate and nitrite (84.7±0.1% and 81.8±0.1%, respectively) was reduced to nitrogen gas. The nitrogen removal and power generation was limited by...

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    We studied the electrochemical behavior of the redox metalloenzyme copper nitrite reductase (CNiR, Achromobacter xylosoxidans) immobilized on a Au(111)‐electrode surface modified by a self‐assembled cysteamine molecular monolayer (SAM) using a combination of cyclic voltammetry and electrochemically......‐controlled atomic force microscopy (in situ AFM). The enzyme showed no voltammetric signals in the absence of nitrite substrate, whereas a strong reductive electrocatalytic signal appeared in the presence of nitrite. Such a pattern is common in protein film and monolayer voltammetry and points to conformational...... changes in the enzyme upon substrate binding. Binding thus either improves the enzyme/electrode contact, or opens intramolecular electron‐transfer channels between the redox center for electron inlet (a type I copper center) and the catalytic site for nitrite reduction (a type II copper center). The in...

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

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    2012-01-01

    Nitrate and nitrite contamination of surface waters (e.g. lakes) has become a severe environmental and health problem, especially in developing countries. The recent demonstration of nitrate reduction at the cathode of microbial fuel cell (MFC) provides an opportunity to develop a new technology...... 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 with biocathode, compared to either the open-circuit operation or with abiotic cathode. The mass balance on nitrogen indicates that most of the removed nitrate and nitrite (84.7±0.1% and 81.8±0.1%, respectively) was reduced to nitrogen gas. The nitrogen removal and power generation was limited by...

  9. Sources of reducing equivalents for nitrite reductase in Pisum arvense roots

    Directory of Open Access Journals (Sweden)

    Grażyna Kłobus

    2014-02-01

    Full Text Available Glucose-6-phosphate and NADP+ as well as malic acid and NADP+ present in the incubation mixture enhanced nitrite reductase (EC 1.6.6.4 activity in Pisum arvense roots. This was manifested by a depression of the nitrite level in the tissues and an increased reduction of nitrites by plastids isolated from P. arvense roots. A marked stimulation of plastid malate dehydrogenase was also observed under the influence of nitrates present in the medium. These results suggest that pyridin nucleotides utilised by NiR during nitrite reduction may be formed not only in processes of glucose-6-phosphate oxidation in the pentosephosphate cycle, but also of malic acid by NADP+-dependent malate dehydrogenase.

  10. 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

  11. The Effects of nitrite on behavior and metamorphosis in cascades frogs ( Rana cascadae)

    OpenAIRE

    Marco, Adolfo; Blaustein, Andrew R

    1999-01-01

    Amphibian metamorphosis is a period of drastic morphologic reorganization, during which larvae experience a decrease in locomotor ability and are more vulnerable to predation. Our results indicate that exposure to sublethal concentrations of nitrite in the water induces behavioral and morphologic changes in the Cascades frog (Rana cascadae). Tadpoles exposed to a nitrite concentration of N-NO— at 3.5 mg/L transformed more slowly than control tadpoles exposed to dechlorinate...

  12. Determination of nitrate and nitrite content of dietary supplements using ion chromatography

    OpenAIRE

    Shah, Iltaf; Petroczi, Andrea; James, Ricky A; Naughton, Declan P

    2013-01-01

    Following the discovery of nitrite and nitrate as pro-drugs of the vasorelaxant nitric oxide, many studies have reported enhanced athletic performance following intake of these ions either intravenously or as a food supplement. The primary aim of this study was to develop a new accurate, reliable and robust ion chromatography based method. The newly developed method was applied to selected foodstuffs in powdered and/or juice form to measure levels of nitrate and nitrite. In addition to the co...

  13. Linkage Isomerization in Heme–NOx Compounds: Understanding NO, Nitrite, and Hyponitrite Interactions with Iron Porphyrins

    OpenAIRE

    Xu, Nan; Yi, Jun; George B. Richter-Addo

    2010-01-01

    Nitric oxide (NO) and its derivatives such as nitrite and hyponitrite are biologically important species of relevance to human health. Much of their physiological relevance stems from their interactions with the iron centers in heme proteins. The chemical reactivities displayed by the heme-NOx species (NOx = NO, nitrite, hyponitrite) are a function of the binding modes of the NOx ligands. Hence, an understanding of the types of binding modes extant in heme-NOx compounds is important if we are...

  14. 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.

    of exposure. Blood was collected by cardiac puncture and bile from the gall bladder after dissection. Livers were excised, weighed and the liver somatic index (LSI) deter- mined as % of body weight. Liver samples obtained on day 6 only were homogenized... of phenanthrene in the presence of nitrite. FF also showed a progressive change with time in both the treatment groups namely, phenanthrene and phenanthrene plus nitrite, the total increase recorded Fig. 1. EROD activity (filled symbols) and bile fluorescence...

  15. Performance and control of biofilm systems with partial nitritation and Anammox for supernatant treatment

    OpenAIRE

    Szatkowska, Beata

    2007-01-01

    Separate treatment of supernatant with dewatering of digested sludge with application of partial nitritation/Anammox process is assessed to be a cost-effective way to remove about 10-15% of influent nitrogen and, thereby, facilitate possibilities to reach required effluent requirements from the plant. The combined partial nitritation/Anammox process can be performed in two separate reactors or in one-stage. Both process options have been investigated in technical- and laboratory-scale pilot p...

  16. Nitrogen polishing in a fully anoxic anammox MBBR treating mainstream nitritation-denitritation effluent.

    Science.gov (United States)

    Regmi, Pusker; Holgate, Becky; Miller, Mark W; Park, Hongkeun; Chandran, Kartik; Wett, Bernhard; Murthy, Sudhir; Bott, Charles B

    2016-03-01

    As nitrogen discharge limits are becoming more stringent, short-cut nitrogen systems and tertiary nitrogen polishing steps are gaining popularity. For partial nitritation or nitritation-denitritation systems, anaerobic ammonia oxidation (anammox) polishing may be feasible to remove residual ammonia and nitrite from the effluent. Nitrogen polishing of mainstream nitritation-denitritation system effluent via anammox was studied at 25°C in a fully anoxic moving bed bioreactor (MBBR) (V = 0.45 m(3) ) over 385 days. Unlike other anammox based processes, a very fast startup of anammox MBBR was demonstrated, despite nitrite limited feeding conditions (influent nitrite = 0.7 ± 0.59 mgN/L, ammonia = 6.13 ± 2.86 mgN/L, nitrate = 3.41 ± 1.92 mgN/L). The nitrogen removal performance was very stable within a wide range of nitrogen inputs. Anammox bacteria (AMX) activity up to 1 gN/m(2) /d was observed which is comparable to other biofilm-based systems. It is generally believed that nitrate production limits nitrogen removal through AMX metabolism. However, in this study, anammox MBBR demonstrated ammonia, nitrite, and nitrate removal at limited chemical oxygen demand (COD) availability. AMX and heterotrophs contributed to 0.68 ± 0.17 and 0.32 ± 0.17 of TIN removal, respectively. It was speculated that nitrogen removal might be aided by denitratation which could be due to heterotrophs or the recently discovered ability for AMX to use short-chain fatty acids to reduce nitrate to nitrite. This study demonstrates the feasibility of anammox nitrogen polishing in an MBBR is possible for nitritation-denitration systems. PMID:26333200

  17. Diversity and enrichment of nitrite-dependent anaerobic methane oxidizing bacteria from wastewater sludge

    OpenAIRE

    Luesken, Francisca A.; van Alen, Theo A.; van der Biezen, Erwin; Frijters, Carla; Toonen, Ger; Kampman, Christel; Hendrickx, Tim L. G.; Zeeman, Grietje; Temmink, Hardy; Strous, Marc; Op den Camp, Huub J. M.; Jetten, Mike S. M.

    2011-01-01

    Recently discovered microorganisms affiliated to the bacterial phylum NC10, named “Candidatus Methylomirabilis oxyfera”, perform nitrite-dependent anaerobic methane oxidation. These microorganisms could be important players in a novel way of anaerobic wastewater treatment where ammonium and residual dissolved methane might be removed at the expense of nitrate or nitrite. To find suitable inocula for reactor startup, ten selected wastewater treatment plants (WWTPs) located in The Netherlands w...

  18. Genomics of a phototrophic nitrite oxidizer: insights into the evolution of photosynthesis and nitrification

    OpenAIRE

    Hemp, James; Lücker, Sebastian; Schott, Joachim; Pace, Laura A.; Johnson, Jena E; Schink, Bernhard; Daims, Holger; Fischer, Woodward W.

    2016-01-01

    Oxygenic photosynthesis evolved from anoxygenic ancestors before the rise of oxygen ~2.32 billion years ago; however, little is known about this transition. A high redox potential reaction center is a prerequisite for the evolution of the water-oxidizing complex of photosystem II. Therefore, it is likely that high-potential phototrophy originally evolved to oxidize alternative electron donors that utilized simpler redox chemistry, such as nitrite or Mn. To determine whether nitrite could have...

  19. The effect of nitrite ion on the electric properties of oxide films on copper

    International Nuclear Information System (INIS)

    The spent nuclear fuel is planned to be stored in steel canisters that have an outer shield made of copper. The copper shield is responsible for the corrosion protection of the canister construction. General corrosion of the copper will not be the limiting factor in the waste repository environment when estimating the life-time of the canister construction. However, localised corrosion, i.e. pitting and stress corrosion cracking (SCC), may destroy the construction. Nitrites, chlorides, sulphides and carbonates has been suggested to promote the localised corrosion of copper. The effect of nitrite on the electrical and electrochemical properties of surface films on copper was studied in this work in oxidising 0.1 M borate buffer and in 0.1 M borate buffer + 0.3 M NaNO2 solution in pH 8.9 at 80 deg C. The film growth rate of Cu2O is decreased in the presence of nitrite ions in the solution. The film resistance growth rate of Cu2O + CuO/Cu(OH)2 films at open circuit potential increased in the presence of nitrite ions in the solution. Nitrite ions do not affect the electrical properties of Cu2O and Cu2O + CuO/Cu(OH)2 films. According to the polarisation curve measurements performed using Cu2O and CuO/Cu(OH)2 films, nitrite affects the electrochemical reactions taking place both in the solution and on the oxide surface. The applicability of SCC models on the explanation of nitrite induced SCC of copper is discussed. A more comprehensive study is needed in order to quantitatively determine the amounts of Cu(I) and Cu(II) ions dissolving on copper in the presence of nitrites. 30 refs, 43 figs, 11 tabs

  20. Measurement and Correlation of Solubility of Ethyl Nitrite in Mixed Solvent

    Institute of Scientific and Technical Information of China (English)

    庞建媛; 刘国维; 马沛生; 方越

    2000-01-01

    An experimental apparatus was used to measure the solubility of ethyl nitrite in mixed solvents under the lower pressure and higher temperature. The solubilities of ethyl nitrite in mixed solvents of ethanol-water at 15℃-40℃ and ethanol-diethyl oxalate at 20℃--40℃ were determined. A Henry constant model has been improved, and the interaction parameters have been fitted from experimental data. The calculation results have been compared with experimental data; the results obtained are satisfactory.

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

    OpenAIRE

    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 ex...

  2. PRELIMINARY STUDY ON GROUNDWATER POLLUTION WITH NITRITES AND NITRATES IN GĂTAIA (TIMIŞ COUNTY)

    OpenAIRE

    Rodica TÖRÖK-OANCE; Daniela TULHINĂ; Mihaela LAZĂR

    2013-01-01

    Nitrate pollution of water is a widespread issue. This study analyses the pollution with nitrites and nitrates in wells from Gătaia. We collected water samples from 17 wells. The nitrites and nitrates content was determined by the photometric method, using the Spectroquant NOVA60 photometer. We analysed following factors impacting pollution: manure deposits, latrines, livestock farms, slope and depth of the groundwater level in wells. The distances between wells and the analysed pollution sou...

  3. Nitrogen Removal from Digested Black Water by One-stage Partial Nitritation and Anammox

    DEFF Research Database (Denmark)

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

    2009-01-01

    rate of ca. 700 mg N L-1 d(-1) was reached over the subsequent 5 months. Suppression of the nitrite oxidizing bacteria at free ammonia levels above 3 mg N L-1 resulted in a nitrogen removal efficiency of 76%. The favorable ratios of both organic and inorganic carbon to nitrogen guaranteed endured......-stage partial nitritation and anammox, which will allow a significant decrease in operational costs compared to conventional nitrification/denitrification....

  4. Nitrite ion-induced fluorescence quenching of luminescent BSA-Au(25) nanoclusters: mechanism and application.

    Science.gov (United States)

    Unnikrishnan, Binesh; Wei, Shih-Chun; Chiu, Wei-Jane; Cang, Jinshun; Hsu, Pang-Hung; Huang, Chih-Ching

    2014-05-01

    Fluorescence quenching is an interesting phenomenon which is highly useful in developing fluorescence based sensors. A thorough understanding of the fluorescence quenching mechanism is essential to develop efficient sensors. In this work, we investigate different aspects governing the nitrite ion-induced fluorescence quenching of luminescent bovine serum albumin stabilized gold nanoclusters (BSA-Au NCs) and their application for detection of nitrite in urine. The probable events leading to photoluminescence (PL) quenching by nitrite ions were discussed on the basis of the results obtained from ultraviolet-visible (UV-Vis) absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), fluorescence measurements, circular dichroism (CD) spectroscopy, zeta potential and dynamic light scattering (DLS) studies. These studies suggested that PL quenching mainly occurred through the oxidation of Au(0) atoms to Au(i) atoms in the core of BSA-Au NCs mediated by nitrite ions. The interference caused by certain species such as Hg(2+), Cu(2+), CN(-), S(2-), glutathione, cysteine, etc. during the nitrite determination by fluorescence quenching was eliminated by using masking agents and optimising the conditions. Based on these findings we proposed a BSA-Au NC-modified membrane based sensor which would be more convenient for the real life applications such as nitrite detection in urine samples. The BSA-Au NC-modified nitrocellulose membrane (NCM) enabled the detection of nitrite at a level as low as 100 nM in aqueous solutions. This Au NC-based paper probe was validated to exhibit good performance for nitrite analysis in environmental water and urine samples, which makes it useful in practical applications. PMID:24634911

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

    Science.gov (United States)

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

    2014-01-01

    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. PMID:24217415

  6. Levels of nitrates and nitrites in chili pepper and ventricina salami

    OpenAIRE

    Giampaolo Colavita; Michele Piccirilli; Luigi Iafigliola; Carmela Amadoro

    2014-01-01

    Ventricina is a traditional sausage made from pork meat produced in the Abruzzi and Molise regions. The aim of this study was to detect the content of nitrates and nitrites in local cultivars of chilli pepper, and their concentration in ventricina samples spiced with the same chilli pepper. Furthermore, it was examined whether, in the samples of ventricina with nitrate addition, the spicing with chilli pepper could exceed the maximum added dose. The concentration of nitrates and nitrites in t...

  7. Effects of agriculture production systems on nitrate and nitrite accumulation on baby-leaf salads

    OpenAIRE

    Aires, Alfredo; Carvalho, Rosa; Eduardo A.S. Rosa; Saavedra, Maria J.

    2013-01-01

    Nitrate and nitrite are widespread contaminants of vegetables, fruits, and waters. The levels of these compounds are increased as a result of using organic wastes from chemical industries, domestic wastes, effluents, nitrogenous fertilizers, and herbicides in agriculture. Therefore, determining the nitrate and nitrite levels in biological, food, and environmental samples is important to protect human health and the environment. In this context, we set this study, in which we report the effect...

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

    OpenAIRE

    Monica NEGREA; Aurel LAZUREANU; Alexa ERSILIA; Alina BULMAGA

    2008-01-01

    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 experiment...

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

    OpenAIRE

    Maria Sandu; Tudor Lupascu; Anatol Tarita; Tatiana Goreacioc; Sergiu Turcan; Elena Mosanu

    2014-01-01

    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 reducti...

  10. Nitrite attenuated peroxynitrite and hypochlorite generation in activated neutrophils.

    Science.gov (United States)

    Ren, Xiaoming; Ding, Yun; Lu, Naihao

    2016-03-15

    Oxidative stress is usually considered as an important factor to the pathogenesis of various diseases. Peroxynitrite (ONOO(-)) and hypochlorite (OCl(-)) are formed in immune cells as a part of the innate host defense system, but excessive reactive oxygen species generation can cause progressive inflammation and tissue damage. It has been proven that through mediating nitric oxide (NO) homeostasis, inorganic nitrite (NO2(-)) shows organ-protective effects on oxidative stress and inflammation. However, the effects of NO2(-) on the function of immune cells were still not clear. The potential role of NO2(-) in modulating ONOO(-) and OCl(-) generation in neutrophil cells was investigated in this study. As an immune cell activator, lipopolysaccharide (LPS) increased both ONOO(-) and OCl(-) production in neutrophils, which was significantly attenuated by NO2(-). NO2(-) reduced superoxide (O2(·-)) generation via a NO-dependent mechanism and increased NO formation in activated neutrophils, suggesting a crucial role of O2(·-) in NO2(-)-mediated reduction of ONOO(-). Moreover, the reduced effect of NO2(-) on OCl(-) production was attributed to that NO2(-) reduced H2O2 production in activated neutrophils without influencing the release of myeloperoxidase (MPO), thus limiting OCl(-) production by MPO/H2O2 system. Therefore, NO2(-) attenuates ONOO(-) and OCl(-) formation in activated neutrophils, opening a new direction to modulate the inflammatory response. PMID:26854590

  11. Nitrite is produced by elicited but not by circulating neutrophils

    Directory of Open Access Journals (Sweden)

    A. G. Stewart

    1993-01-01

    Full Text Available The generation of nitrite (NO2− was used as an index of the production of nitric oxide by human and rat polymorphonuclear leukocytes (PMN and rat peritoneal macrophages. Human peripheral blood PMN did not produce significant levels of NO2−. Attempts to induce NO2− generation in human PMN by incubation with GM–CSF (1 nM, TNFα (0.3 nM, endotoxin (1 μg/ml or formyl-Met-Leu-Phe (100 nM for up to 16 h were not successful. Addition of human PMN primed by GM–CSF (1 nM to rabbit aortic ring preparations precontracted with phenylephrine had no effect on tone. In contrast to these observations, PMN, isolated from the peritoneum of oyster glycogen treated rats, generated NO2− via a pathway sensitive to inhibition by the nitric oxide synthase inhibitor, NG-monomethyl L-arginine. However, peripheral blood rat PMN obtained from the same animals did not produce NO2−, even during prolonged incubation for periods of up to 16 h. It is suggested that detectable NO production by PMN requires NO synthase activity to be induced either by the process of PMN migration or by exposure to certain cytokines produced locally at the site of inflammation.

  12. 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.

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

    International Nuclear Information System (INIS)

    Potassium nitrate labeled with 15N is often used as a tracer in studies of N dynamics in soil and water systems. Typically, 0.8% NO2- impurity has been found in the batches of K15NO3 enriched to 99 atom % excess 15N that were purchased by our laboratory. Nitrite is an intermediate in several N cycling processes so its addition when adding NO3- could produce misleading results. We have developed a safe, simple, and inexpensive method to remove NO2- impurity from any NO3- solution in a water matrix. The principle is the oxidation of NO2- to NO3- by UV light in the presence of a heterogenous TiO2 catalyst. A NO2- concentration of 0.2 mM in 100 mL of 0.2 M NO3- solution could be oxidized in 12 min using 0.5 g L-1 TiO2 in a specially constructed photoreactor with a 75-W UV facial tanning lamp. For the routine removal of NO2-, use of the same TiO2 concentration in a standard beaker worked equally well when the irradiation time was extended to 2.5 h. After irradiation, the TiO2 is easily and totally removed from the solution by membrane filtration. (author)

  14. 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. PMID:26609554

  15. 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.

  16. Corrosion risk associated with microbial souring control using nitrate or nitrite.

    Science.gov (United States)

    Hubert, Casey; Nemati, Mehdi; Jenneman, Gary; Voordouw, Gerrit

    2005-08-01

    Souring, the production of hydrogen sulfide by sulfate-reducing bacteria (SRB) in oil reservoirs, can be controlled through nitrate or nitrite addition. To assess the effects of this containment approach on corrosion, metal coupons were installed in up-flow packed-bed bioreactors fed with medium containing 8 mM sulfate and 25 mM lactate. Following inoculation with produced water to establish biogenic H(2)S production, some bioreactors were treated with 17.5 mM nitrate or up to 20 mM nitrite, eliminating souring. Corrosion rates were highest near the outlet of untreated bioreactors (up to 0.4 mm year(-1)). Nitrate (17.5 mM) eliminated sulfide but gave pitting corrosion near the inlet of the bioreactor, whereas a high nitrite dose (20 mM) completely eliminated microbial activity and associated corrosion. More gradual, step-wise addition of nitrite up to 20 mM resulted in the retention of microbial activity and localized pitting corrosion, especially near the bioreactor inlet. We conclude that: (1) SRB control by nitrate or nitrite reduction shifts the corrosion risk from the bioreactor outlet to the inlet (i.e. from production to injection wells) and (2) souring treatment by continuous addition of a high inhibitory nitrite dose is preferable from a corrosion-prevention point of view. PMID:15711941

  17. 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 4.1×10(3) (L mol(-1) cm(-1)) and lower than 10%, respectively. PMID:25965167

  18. Sensitivity to nitrate and nitrite in pond-breeding amphibians from the Pacific Northwest, USA

    Energy Technology Data Exchange (ETDEWEB)

    Marco, A.; Quilchano, C.; Blaustein, A.R.

    1999-12-01

    In static experiments, the authors studied the effects of nitrate and nitrate solutions on newly hatched larvae of five species of amphibians, namely Rana pretiosa, Rana aurora, Bufo boreas, Hyla regilla, and Ambystoma gracile. When nitrate or nitrite ions were added to the water, some larvae of some species reduced feeding activity, swam less vigorously, showed disequilibrium and paralysis, suffered abnormalities and edemas, and eventually died. The observed effects increased with both concentration and time, and there were significant differences in sensitivity among species. Ambrystoma gracile displayed the highest acute effect in water with nitrate and nitrite. The three ranid species had acute effects in water with nitrite. In chronic exposures, R. pretiosa was the most sensitive species to nitrates and nitrites. All species showed 15-d LC50s lower than 2 mg N-NO{sub 2{sup {minus}}}/L. For both N ions, B. boreas was the least sensitive amphibian. All species showed a high morality at the US Environmental Protection Agency-recommended limits of nitrite for warm-water fishes and a significant larval mortality at the recommended limits of nitrite concentration for drinking water. The recommended levels of nitrate for warm-water fishes were highly toxic for R. pretiosa and A. gracile larvae.

  19. Effect of lycopene on serum nitrite-nitrate levels in diabetic rats

    Directory of Open Access Journals (Sweden)

    Sevim Ç Yegin

    2015-01-01

    Full Text Available The effect of lycopene on serum nitrate-nitrite levels was investigated in diabetic rats. In this investigation, 28 Wistar rats were divided into 4 groups, each of seven rats. These groups were control group, diabetes group, diabetes-lycopene group and lycopene group. The concentration of nitrite and nitrate was detected at high levels in diabetes group, diabetes-lycopene group and lycopene group as compared with the control group (P<0.05. Especially, the increase in the levels of nitrate in diabetes group and lycopene group was statistically significant when compared with diabetes-lycopene group and control group (P<0.05. In addition, we also determined the proportion of nitrite/nitrate for nitric oxide radical formation. Therefore, it is important to investigate the recovery and stability of nitrite and nitrate in samples. As a result of this study, it was observed that the amounts of nitrate and nitrite increased due to oxidative stress in diabetes and also application of antioxidant lycopene caused an increase in the amounts of nitrate and nitrite levels.

  20. Use of gamma radiation on control of Clostridium botulinum in mortadella formulated with different nitrite levels

    Science.gov (United States)

    Dutra, Monalisa Pereira; Aleixo, Glécia de Cássia; Ramos, Alcinéia de Lemos Souza; Silva, Maurício Henriques Louzada; Pereira, Marcio Tadeu; Piccoli, Roberta Hilsdorf; Ramos, Eduardo Mendes

    2016-02-01

    This study investigated the effects of applying different doses of gamma radiation (0, 10 and 20 kGy) on Clostridium botulinum spores (107 spores/g) inoculated into mortadellas with different nitrite contents (0, 150 and 300 ppm). We also evaluated the order of application of heat (cooking) and irradiation processing. The products were evaluated for survival of C. botulinum, pH, water activity (Aw), redox potential (Eh) and residual nitrite content. In the non-irradiated raw batters, almost all spores could be recovered when no nitrite was added and only half was recovered with the addition of 150 ppm of nitrite. The use of 150 ppm of nitrite was able to inhibit the germination or growth of C. botulinum in non-irradiated cooked mortadellas after 48 h of processing. However, after 30 days of chilling storage (4 °C), it was possible to recover 105 UFC/g of this microorganism. The gamma irradiation (>10 kGy) had a positive effect on the inactivation of C. botulinum in mortadellas, independent of the sodium nitrite level used and the cooking/irradiation processing order.

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

    Directory of Open Access Journals (Sweden)

    Ruiping Wang

    2013-12-01

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

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

    International Nuclear Information System (INIS)

    The electrocatalytic reduction of nitrite has been studied by ferricyanide at the surface of carbon paste electrode. Cyclic voltammetry and chronoamperometry techniques were used to investigate the suitability of ferricyanide as a mediator for the electrocatalytic nitrite reduction in aqueous solution with various pH. Results showed that pH 0.00 is the most suitable for this purpose. In the optimum pH, the electrocatalytic ability about 700 mV can be seen and the homogeneous second-order rate constant (k s) for nitrite coupled catalytically to ferricyanide was calculated 2.75 x 103 M-1 s-1 by Nicholson-Shain method. Also, electron transfer coefficients (α) for ferricyanide was determined by using various electrochemical approaches such as Tafel plot in the absence and presence of nitrite 0.556 and 0.760, respectively. The catalytic reduction peak current was linearly dependent on the nitrite concentration and the linearity range obtained was 5.00 x 10-5 to 1.00 x 10-3 M. Detection limit has been found to be 2.63 x 10-5 M (2σ). This method has been applied as a selective, simple and precise method for determination of nitrite in real sample

  3. Effect of nitrite on the formation of halonitromethanes during chlorination of organic matter from different origin

    Science.gov (United States)

    Hong, Huachang; Qian, Lingya; Xiao, Zhuoqun; Zhang, Jianqing; Chen, Jianrong; Lin, Hongjun; Yu, Haiying; Shen, Liguo; Liang, Yan

    2015-12-01

    Occurrence of halonitromethanes (HNMs) in drinking water has been a public concern due to the potential risks to human health. Though quite a lot of work has been carried out to understand the formation of HNMs, the relationship between HNMs formation and the nitrite remains unclear. In this study, the effects of nitrite on the formation of HNMs during chlorination of organic matter from different origin were assessed. Organic matter (OM) derived from phoenix tree (fallen leaves: FLOM; green leaves: GLOM) and Microcystis aeruginosa (intracellular organic matter: IOM) were used to mimic the allochthonous and autochthonous organic matter in surface water, respectively. Results showed that HNMs yields were significantly enhanced with the addition of nitrite, and the highest enhancement was observed for FLOM, successively followed by GLOM and IOM, suggesting that the contribution of nitrite to HNMs formation was positively related with SUVA (an indicator for aromaticity) of OM. Therefore, the nitrite contamination should be strictly controlled for the source water dominated by allochthonous OM, which may significantly reduce the formation of HNMs during chlorination. Moreover, given a certain nitrite level, the higher pH resulted in higher stimulation of HNM formation, yet the chlorine dose (always added in excess resulting in residual reactive chlorine), reaction time and temperature did not show obvious influence.

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

    Science.gov (United States)

    Yan, Ruiwen; Kappler, Andreas; Peiffer, Stefan

    2015-10-01

    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. PMID:26335043

  5. Inorganic nitrite and nitrate: evidence to support consideration as dietary nutrients.

    Science.gov (United States)

    Bryan, Nathan S; Ivy, John L

    2015-08-01

    There are now indisputable health benefits of nitrite and nitrate derived from food sources or when administered in a clinical setting for specific diseases. Most of the published reports identify the production of nitric oxide (NO) as the mechanism of action for nitrite and nitrate. Basic science as well as clinical studies demonstrates that nitrite and/or nitrate can 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 and then nitrite must be further reduced to NO along the physiological oxygen gradient. The purpose of this review is to define their role as indispensable nutrients needed for maintaining NO homeostasis and describe the daily intake required to achieve a threshold of activation as well as define the upper tolerable limits based on published literature in PubMed databases. Optimal ranges of intake will be discussed to maximize the benefits while mitigating any potential risks of overexposure to these naturally occurring anions. This information will allow for future research using safe and effective doses of nitrite and nitrate in long-term clinical trials to effectively test their roles in disease prevention or treatment. PMID:26189149

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

    Science.gov (United States)

    Koch, Hanna; Lücker, Sebastian; Albertsen, Mads; Kitzinger, Katharina; Herbold, Craig; Spieck, Eva; Nielsen, Per Halkjaer; Wagner, Michael; Daims, Holger

    2015-09-01

    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, we identified ecophysiological traits that contribute to the ecological success of Nitrospira. Unexpectedly, N. moscoviensis possesses genes coding for a urease and cleaves urea to ammonia and CO2. Ureolysis was not observed yet in nitrite oxidizers and enables N. moscoviensis to supply ammonia oxidizers lacking urease with ammonia from urea, which is fully nitrified by this consortium through reciprocal feeding. The presence of highly similar urease genes in Nitrospira lenta from activated sludge, in metagenomes from soils and freshwater habitats, and of other ureases in marine nitrite oxidizers, suggests a wide distribution of this extended interaction between ammonia and nitrite oxidizers, which enables nitrite-oxidizing bacteria to indirectly use urea as a source of energy. A soluble formate dehydrogenase lends additional ecophysiological flexibility and allows N. moscoviensis to use formate, with or without concomitant nitrite oxidation, using oxygen, nitrate, or both compounds as terminal electron acceptors. Compared with Nitrospira defluvii from lineage I, N. moscoviensis shares the Nitrospira core metabolism but shows substantial genomic dissimilarity including genes for adaptations to elevated oxygen concentrations. Reciprocal feeding and metabolic versatility, including the participation in different nitrogen cycling processes, likely are key factors for the niche partitioning, the ubiquity, and the high diversity of Nitrospira in natural and engineered ecosystems. PMID:26305944

  7. 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.

  8. 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.

  9. 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)

  10. CALCIUM SOAP LUBRICANTS

    OpenAIRE

    Alaz, Izer; Tugce, Nefise; Devrim, Balköse

    2014-01-01

    The article studies the properties of calcium stearate (CaSt2) and lubricants produced on its basis. These lubricants were prepared using sodium stearate and calcium chloride by subsidence from aqueous solutions. The CaSt2 and the light fraction of crude oil were mixed together to obtain lubricating substances. The article shows that CaSt2 had the melting temperature of 142.8 C that is higher than the melting temperature of crude oil (128 C). The compositions of obtained lubricants were stu...

  11. CALCIUM-INDUCED SUPRAMOLECULAR STRUCTURES IN THE CALCIUM CASEINATE SYSTEM

    Science.gov (United States)

    The molecular details deciphering the spontaneous calcium-induced protein aggregation process in the calcium caseinate system remain obscure. Understanding this complex process could lead to potential new applications of this important food ingredient. In this work, we studied calcium-induced supra...

  12. A sensor for calcium uptake

    OpenAIRE

    Collins, Sean; Meyer, Tobias

    2010-01-01

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

  13. Children's Bone Health and Calcium

    Science.gov (United States)

    ... Trials Resources and Publications Children's Bone Health and Calcium: Condition Information Skip sharing on social media links ... straight, walk, run, and lead an active life. Calcium is one of the key dietary building blocks ...

  14. Single stage biological nitrogen removal by nitritation and anaerobic ammonium oxidation in biofilm systems.

    Science.gov (United States)

    Helmer, C; Tromm, C; Hippen, A; Rosenwinkel, K H; Seyfried, C F; Kunst, S

    2001-01-01

    In full scale wastewater treatment plants with at times considerable deficits in the nitrogen balances, it could hitherto not be sufficiently explained which reactions are the cause of the nitrogen losses and which micro-organisms participate in the process. The single stage conversion of ammonium into gaseous end-products--which is henceforth referred to as deammonification--occurs particularly frequently in biofilm systems. In the meantime, one has succeeded to establish the deammonification processes in a continuous flow moving-bed pilot plant. In batch tests with the biofilm covered carriers, it was possible for the first time to examine the nitrogen conversion at the intact biofilm. Depending on the dissolved oxygen (DO) concentration, two autotrophic nitrogen converting reactions in the biofilm could be proven: one nitritation process under aerobic conditions and one anaerobic ammonium oxidation. With the anaerobic ammonium oxidation, ammonium as electron donor was converted with nitrite as electron acceptor. The end-product of this reaction was N2. Ammonium and nitrite did react in a stoichiometrical ratio of 1:1.37, a ratio which has in the very same dimension been described for the ANAMMOX-process (1:1.31 +/- 0.06). Via the oxygen concentration in the surrounding medium, it was possible to control the ratio of nitritation and anaerobic ammonium oxidation in the nitrogen conversion of the biofilm. Both processes were evenly balanced at a DO concentration of 0.7 mg/l, so that it was possible to achieve a direct, almost complete elimination of ammonium without addition of nitrite. One part of the provided ammonium did participate in the nitritation, the other in the anaerobic ammonium oxidation. Through the aerobic ammonium oxidation into nitrite within the outer oxygen supplied layers of the biofilm, the reaction partner was produced for the anaerobic ammonium oxidation within the inner layers of the biofilm. PMID:11379106

  15. Quantitative analysis of nitrate and nitrite contents in vegetables commonly consumed in Delta State, Nigeria.

    Science.gov (United States)

    Onyesom, I; Okoh, P N

    2006-11-01

    Plasma thiocyanate has been reported to be high among cassava-eating populations such as that in Nigeria because of the cyanide content of cassava. Thiocyanate, which is secreted into the stomach contents of animals, has been demonstrated to catalyse the formation of nitrosamines (potent carcinogens) in the stomach from secondary amines and nitrite. The main source of the nitrite precursor in this environment is vegetables, primarily eaten as the chief supplier of proteins. The present study attempts to analyse the levels of nitrate and nitrite in vegetables commonly grown and consumed in Delta State, Nigeria. The nitrate and nitrite contents in green vegetable (Amaranthus spp.), bitter leaf (Vernonia amygdalina), pumpkin (Telfaria occidentalis) and water leaf (Talinum triangulare) grown in different localities of the state were determined by standard analytical procedures. The results show that those vegetables grown in the industrialised urban centres of the state had higher nitrate (223 (SD 71) mg/kg dry weight; P0.05) levels when compared with the same species (188 (SD 77) mg nitrate/kg dry weight and 10.9 (SD 1.1) mg nitrite/kg dry weight) cultivated in less industrialised suburbs. We conclude that frequent consumption of such vegetables whose nitrate and nitrite contents are high by cassava-eating individuals might put them at risk of developing stomach cancer and other possible results of nitrate and/or nitrite toxicity. In order to avoid an outbreak in our communities, appropriate agencies should monitor and regulate the release of chemicals into the environment. In the meantime, the cultivation and consumption of vegetables grown in industrialised areas of the state should be discouraged. PMID:17092380

  16. Crystal Structures of the Nitrite and Nitric Oxide Complexes of Horse Heart Myoglobin

    Energy Technology Data Exchange (ETDEWEB)

    Copeland,D.; Soares, A.; West, A.; Richter-Addo, G.

    2006-01-01

    Nitrite is an important species in the global nitrogen cycle, and the nitrite reductase enzymes convert nitrite to nitric oxide (NO). Recently, it has been shown that hemoglobin and myoglobin catalyze the reduction of nitrite to NO under hypoxic conditions. We have determined the 1.20 Angstroms resolution crystal structure of the nitrite adduct of ferric horse heart myoglobin (hh Mb). The ligand is bound to iron in the nitrito form, and the complex is formulated as Mb{sup III}(ONO{sup -}). The Fe-ONO bond length is 1.94 Angstroms, and the O-N-O angle is 113 degrees. In addition, the nitrite ligand is stabilized by hydrogen bonding with the distal His64 residue. We have also determined the 1.30 Angstroms resolution crystal structures of hh Mb{sup II}NO. When hh Mb{sup II}NO is prepared from the reaction of metMb{sup III} with nitrite/dithionite, the FeNO angle is 144 degrees with a Fe-NO bond length of 1.87 Angstroms. However, when prepared from the reaction of NO with reduced Mb{sup II}, the FeNO angle is 120 degrees with a Fe-NO bond length of 2.13 Angstroms. This difference in FeNO conformations as a function of preparative method is reproducible, and suggests a role of the distal pocket in hh Mb{sup II}NO in stabilizing local FeNO conformational minima.

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

    International Nuclear Information System (INIS)

    Highlights: ► The correlation of DO to N2O emission under denitrification via nitrite was confirmed. ► The higher nitrite ratio in NOx (nitrite and nitrate) caused the more N2O emission. ► Reactor feed mode and nitrite loading rate had significant impact on N2O emission which was related to nitrite level. - Abstract: Nitrous oxide (N2O) emission has been observed during denitrification of nitrate via nitrite as intermediate. With a laboratory-scale reactor (2.4 L), the N2O emission was characterized under a gradient of DO concentration from 0 to 0.7 mg/L, different ratio of nitrite versus nitrate and different nitrite feed mode. The N2O emission was influenced by the level of dissolved oxygen (DO) and nitrite accumulation. The higher DO level and the higher ratio of nitrite versus nitrate resulted in the higher N2O emission. Using nitrite as sole electron acceptor at the same loading rate, the sequence of N2O emission with three different feed modes was: pulse > step-wise > continuous feed. The N2O emitted in pulse feed reactors was 3.1–4.2 and 8.2–11.7 folds of that in the step-wise feed and continuous feed reactors, respectively. With continuous feed mode, the impact of DO concentration on the mass of N2O emitted was limited while the higher N2O emission occurred at the higher nitrite loading rate.

  18. Ameliorating Effect of Chloride on Nitrite Toxicity to Freshwater Invertebrates with Different Physiology: a Comparative Study Between Amphipods and Planarians

    OpenAIRE

    Alonso, A.; Camargo, J.A.

    2008-01-01

    High nitrite concentrations in freshwater ecosystems may cause toxicity to aquatic animals. These living organisms can take nitrite up from water through their chloride cells, subsequently suffering oxidation of their respiratory pigments (hemoglobin, hemocyanin). Because NO2¿ and Cl¿ ions compete for the same active transport site, elevated chloride concentrations in the aquatic environment have the potential of reducing nitrite toxicity. Although this ameliorating effect is well documented ...

  19. The role of red blood cell S-nitrosation in nitrite bioactivation and its modulation by leucine and glucose

    OpenAIRE

    Nadeem Wajih; Xiaohua Liu; Pragna Shetty; Swati Basu; Hanzhi Wu; Neil Hogg; Patel, Rakesh P.; Furdui, Cristina M.; Kim-Shapiro, Daniel B.

    2016-01-01

    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....

  20. Reducing the amount of nitrites in the production of pasteurized organic meat : summary of the project and implications

    OpenAIRE

    Stegeman, D.; Verkleij, T.J.

    2008-01-01

    In the production of organic meat products like cold meats, nitrites and nitrates are used for several reasons: for the antimicrobial and anti-oxidative properties, forming and stabilizing the red, cured meat colour, and for forming a cured flavour. From literature, it is concluded that it is not possible to substitute nitrite in the production of organic cooked cured meat products with a single additive or combination of additives without changing the quality of the meat products. Nitrite is...

  1. Calcium ion channel and epilepsy

    Institute of Scientific and Technical Information of China (English)

    Yudan Lü; Weihong Lin; Dihui Ma

    2006-01-01

    OBJECTIVE: To review the relationship between calcium ion channel and epilepsy for well investigating the pathogenesis of epilepsy and probing into the new therapeutic pathway of epilepsy.DATA SOURCES: A computer-based online research Calcium ion channel and epilepsy related articles published between January 1994 and December 2006 in the CKNI and Wanfang database with the key words of "calcium influxion, epilepsy, calcium-channel blocker". The language was limited to Chinese. At the same time,related articles published between January 1993 and December 2006 in Pubmed were searched for on online with the key words of "calcium influxion, epilepsy" in English.STUDY SELECTION: The materials were selected firstly. Inclusive criteria: ① Studies related to calcium ion channel and the pat1hogenesis of epilepsy. ② Studies on the application of calcium ion channel blocker in the treatment of epilepsy. Exclusive criteria: repetitive or irrelated studies.DATA EXTRACTION: According to the criteria, 123 articles were retrieved and 93 were excluded due to repetitive or irrelated studies. Altogether 30 articles met the inclusive criteria, 11 of them were about the structure and characters of calcium ion channel, 10 about calcium ion channel and the pathogenesis of epilepsy and 9 about calcium blocker and the treatment of epilepsy.DATA SYNTHESIS: Calcium ion channels mainly consist of voltage dependent calcium channel and receptor operated calcium channel. Depolarization caused by voltage gating channel-induced influxion is the pathological basis of epileptic attack, and it is found in many studies that many anti-epileptic drugs have potential and direct effect to rivalizing voltage-dependent calcium ion channel.CONCLUSION: Calcium influxion plays an important role in the seizure of epilepsy. Some calcium antagonists seen commonly are being tried in the clinical therapy of epilepsy that is being explored, not applied in clinical practice. If there are enough evidences to

  2. 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...

  3. 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.

  4. 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...... renal tubule and then discuss why not all gene defects that cause renal tubular acidosis are associated with hypercalciuria and nephrocalcinosis....

  5. 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. PMID:26439519

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

    Directory of Open Access Journals (Sweden)

    W.J. Wiese

    2001-07-01

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

  7. Effects of low concentrations of bisulfite--sulfite and nitrite on microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    Wodzinski, R.S.; Labeda, D.P.; Alexander, M.

    1978-04-01

    A wide range of microorganisms was tested to determine their sensitivity to low concentrations of bisulfite-sulfite and nitrite, solubility products of SO/sub 2/ and NO/sub 2/, respectively. Photosynthesis by blue-green algae (cyanobacteria) was more strongly inhibited by 0.1 mM bisulfite-sulfite and 1 mM nitrite at pH 6.0 than photosynthesis by eucaryotic algae and respiration of bacteria, fungi, and protozoa. At pH 7.7, blud-green algae were still more sensitive to busulfite-sulfite and nitrite than eurcaryotic algae, but the toxicity of bisulfite-sulfite and nitrite decreased as the pH increased. Photosynthesis by Anabaena flos-aquae at pH 6.0 was inhibited 25% by a bisulfite-sulfite concentration of 10 ..mu..M and 15% by a nitrite concentration of 50 ..mu..M. Photosynthesis by the blud-green alga, Lyngbya sp., was not exceptionally sensitive to chlorate and thiosulfate. Acetylene-reducing activity of Beijerinckia indica was completely inhibited by 0.1 mM bisulfite-sulfite at pH 4.0, the suppression being decreased with increasing pH.

  8. Biochemical Studies On The Effect Of Sodium Nitrite And/Or Glutathione Treatment On Male Rats

    Directory of Open Access Journals (Sweden)

    Eman Helal; *Zahkok, S; **Ghada Z A Soliman; * Al-Kassas, M;

    2008-03-01

    Full Text Available Introduction: Using food preservatives as sodium nitrite are increased in industrial food productions. Teratogenic, mutagenic and carcinogenic effects have been related to using of some food preservatives. Purpose: To study the effect of sodium nitrite (food additives and treated with glutathione (nature antitoxic on rats. Material And Methods: Certain parameters were measured as percentage of body weight change, body temperature, heart rates, Red & white blood cells count (RBCs & WBCs, hemoglobin (Hb level, hematocrite (Hct value, serum total lipids, serum cholesterol, serum total protein, serum albumin, serum glucose, serum alanine transaminase and aspartate transaminase (ALT & AST activity and serum total cholinesterase. The organs, body weight were detected. Organs were prepared for biochemical analysis. Results: Body weight, respiration rate, hepatosomatic index, RBCs & WBCs count, Hb, Hct, serum total lipids, protein, albumin, A/G ratio, liver and muscle total lipids and cholesterol were significantly reduced while serum cholesterol, kidney total lipids and cholesterol, serum ALT & AST was significantly increased. Supplementation of sodium nitrite to rats had no effect on serum glucose level or cholinesterase activity Conclusion: Due to the hazardous effect of food additives as sodium nitrite, it is recommended that the use of sodium nitrite as food additives must be limited and gluathione has the ability to prevent its toxic effect

  9. Nitrate as a source of nitrite and nitric oxide during exercise hyperemia in rat skeletal muscle.

    Science.gov (United States)

    Piknova, Barbora; Park, Ji Won; Kwan Jeff Lam, Kai; Schechter, Alan N

    2016-05-01

    The presence of nitric oxide (NO) synthase enzymes, mainly the NOS1 isoform, in skeletal muscle had been well established; however in the last decade it has been realized that NO may also be produced by reduction of nitrate and tissue nitrite. We have recently shown that rodent skeletal muscle contains unusually high concentrations of nitrate, compared to blood and other tissues, likely produced by oxidation of NOS1-produced NO. In the present study we measured nitrate and nitrite levels in Wistar rat leg tissue before and after acute and chronic exercise of the animals on a treadmill. We found a very large decrease of muscle nitrate levels immediately after exercise accompanied by a transient increase of nitrite levels. A significant decrease in blood nitrate levels accompanied the changes in muscle levels. Using skeletal muscle tissue homogenates we established that xanthine oxidoreductase (XOR) is at least partially responsible for the generation of nitrite and/or NO from nitrate and that this effect is increased by slight lowering of pH and by other processes related to the exercise itself. We hypothesize that the skeletal muscle nitrate reservoir contributes significantly to the generation of nitrite and then, probably via formation of NO, exercise-induced functional hyperemia. A model for these metabolic interconversions in mammals is presented. These reactions could explain the muscle-generated vasodilator causing increased blood flow, with induced contraction, exercise, or hypoxia, postulated more than 100 years ago. PMID:27000467

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

    Science.gov (United States)

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

    2016-11-01

    The effects of sodium nitrite and ascorbate on lipid and protein oxidation were studied during the ripening process of dry fermented sausages. Samples were taken at day 0, 2, 8, 14, 21 and 28 of ripening to assess lipid (malondialdehyde) and protein (carbonyls and sulfhydryl groups) oxidation. Sodium ascorbate and nitrite were separately able to reduce the formation of malondialdehyde. Their combined addition resulted in higher amounts of carbonyl compounds compared to their separate addition or the treatment without any of both compounds. Moreover, sodium nitrite limited the formation of γ-glutamic semialdehyde whereas sodium ascorbate showed a pro-oxidant effect. A loss of thiol groups was observed during ripening, which was not affected by the use of sodium ascorbate nor sodium nitrite. In conclusion, sodium nitrite and ascorbate affected protein and lipid oxidation in different manners. The possible pro-oxidant effect of their combined addition on carbonyl formation might influence the technological and sensory properties of these products. PMID:27424306

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    Nitrate and nitrite ions are of considerable interest, both for their widespread use in commercial and research contexts and because of their central role in the global nitrogen cycle. The chemistry of atmospheric aerosols, wherein nitrate is abundant, has been found to depend on the interfacial behavior of ionic species. The interfacial behavior of ions is determined largely by their hydration properties; consequently, the study of the hydration and interfacial behavior of nitrate and nitrite comprises a significant field of study. In this work, we describe the study of aqueous solutions of sodium nitrate and nitrite via X-ray absorption spectroscopy (XAS), interpreted in light of first-principles density functional theory electronic structure calculations. Experimental and calculated spectra of the nitrogen K-edge XA spectra of bulk solutions exhibit a large 3.7 eV shift between the XA spectra of nitrate and nitrite resulting from greater stabilization of the nitrogen 1s energy level in nitrate. A similar shift is not observed in the oxygen K-edge XA spectra of NO3− and NO2−. The hydration properties of nitrate and nitrite are found to be similar, with both anions exhibiting a similar propensity towards ion pairing

  13. Effects of nitrite on phosphate uptake in anaerobic-oxic process

    Institute of Scientific and Technical Information of China (English)

    LI Jie; XIONG Biyong; ZHANG Shude; YANG Hong; ZHANG Jie

    2007-01-01

    An anaerobic-oxic(A/O)biological phosphorus removal reactor was operated to study the effect of nitrite on phosphate uptake.The phosphorus uptake profile was determined under different operating conditions.The results indicated that in addition to oxygen and nitrate(DPBNa,nitrate denitrifying phosphorus removal),to some extent,nitrite could also serve as an electron acceptor to achieve nitrite denitrifying phosphorus removal(DPBNi).The quantity and rate of phosphorus uptake of DPBNi,however,were evidently lower than that of DPBNa.The experiment results revealed that nitrite would bring toxic action to phosphate accumulating organisms(PAOs)when NO2- -N≥93]7 mg/L.The nitrite existing in the anoxic reactor made no difference to the quantity and rate of denitrifying phosphorus removal,but it could reduce the consumption of nitrate.Moreover,the data showed that the aerobic phosphate uptake of DPBNi was lower than that of anaerobic phosphorus-released sludge in a traditional A/O process.However,there was not much difference between these two kinds of sludge in terms of the total phosphorus uptake quantity and the effluent quality.

  14. Influence of operating conditions on nitrous oxide formation during nitritation and nitrification.

    Science.gov (United States)

    Schneider, Y; Beier, M; Rosenwinkel, K-H

    2014-10-01

    Nitrous oxide (N2O), a strong greenhouse gas, can be produced by ammonium-oxidizing bacteria (AOB) as a by-product of ammonium oxidation and can potentially be formed in all types of nitrification processes. However, partial nitritation has been reported to cause significantly higher N2O emissions than complete nitrification. In the study presented here, the mechanisms and factors that drive N2O formation by AOB were investigated with respect to different operational strategies to achieve nitrite accumulation base on combined evaluation of oxygen uptake rate (OUR) and N2O formation rate. On the one hand, N2O formation during partial nitritation and nitrification in a continuously stirred tank reactor (CSTR) with continuous aerobic conditions was observed. On the other hand, the effect of intermittent aeration on N2O formation during nitrification was investigated. The presence of nitrite, the extend of sludge-specific ammonium loading, low oxygen concentration, and transition from aerobic to anoxic conditions significantly increased N2O formation in this reactor independently from each other, indicating that different formation pathways, supposedly via nitrite or hydroxylamine, were active. PMID:24928380

  15. Cultivation of a novel cold-adapted nitrite oxidizing betaproteobacterium from the Siberian Arctic.

    Science.gov (United States)

    Alawi, Mashal; Lipski, André; Sanders, Tina; Pfeiffer, Eva Maria; Spieck, Eva

    2007-07-01

    Permafrost-affected soils of the Siberian Arctic were investigated with regard to identification of nitrite oxidizing bacteria active at low temperature. Analysis of the fatty acid profiles of enrichment cultures grown at 4 degrees C, 10 degrees C and 17 degrees C revealed a pattern that was different from that of known nitrite oxidizers but was similar to fatty acid profiles of Betaproteobacteria. Electron microscopy of two enrichment cultures grown at 10 degrees C showed prevalent cells with a conspicuous ultrastructure. Sequence analysis of the 16S rRNA genes allocated the organisms to a so far uncultivated cluster of the Betaproteobacteria, with Gallionella ferruginea as next related taxonomically described organism. The results demonstrate that a novel genus of chemolithoautotrophic nitrite oxidizing bacteria is present in polygonal tundra soils and can be enriched at low temperatures up to 17 degrees C. Cloned sequences with high sequence similarities were previously reported from mesophilic habitats like activated sludge and therefore an involvement of this taxon in nitrite oxidation in nonarctic habitats is suggested. The presented culture will provide an opportunity to correlate nitrification with nonidentified environmental clones in moderate habitats and give insights into mechanisms of cold adaptation. We propose provisional classification of the novel nitrite oxidizing bacterium as 'Candidatus Nitrotoga arctica'. PMID:18062041

  16. A sensitive fluorimetric method for determination of trace amounts of nitrite based on luminescence energy transfer

    International Nuclear Information System (INIS)

    An efficient luminescence energy transfer (LET) system based on terbium(III)-sodium hexametaphosphate (Tb/SHMP) chelates as donor and 4-((4-(2-aminoethylamino)naphthalen-1-yl)diazenyl)benzenesulfonic acid dihydrochloride (ANDBS) as acceptor was developed for sensitive determination of trace nitrite. Stable and strong fluorescence Tb/SHMP chelates were prepared in aqueous solution. Based on Griess Reaction, ANDBS was generated by the quantitative reaction of nitrite, sulfanilamide and N-(1-naphtyl)-ethylenediamine dihydrochloride (N1NED). The degree of the overlap was effective for LET between the emission spectrum of Tb/SHMP chelates and the absorption spectrum of ANDBS. Based on the luminescence intensity quenching of Tb/SHMP chelates in proportion to the trace amounts of nitrite, a new assay for the selective and sensitive determination of nitrite was developed. Under the optimum conditions, the linear calibration graph was obtained with a linear range of 0.00040-0.20 μg mL-1 (R=0.99657). The detection limit of NO2- was 0.00010 μg mL-1 (R=0.99657). The method was applied successfully to the determination of nitrite for synthetic samples.

  17. DFT Study on Enzyme Turnover Including Proton and Electron Transfers of Copper-Containing Nitrite Reductase.

    Science.gov (United States)

    Lintuluoto, Masami; Lintuluoto, Juha M

    2016-08-23

    The reaction mechanism of copper-containing nitrite reductase (CuNiR) has been proposed to include two important events, an intramolecular electron transfer and a proton transfer. The two events have been suggested to be coupled, but the order of these events is currently under debate. We investigated the entire enzyme reaction mechanism of nitrite reduction at the T2 Cu site in thermophilic Geobacillus CuNiR from Geobacillus thermodenitrificans NG80-2 (GtNiR) using density functional theory calculations. We found significant conformational changes of His ligands coordinated to the T2 Cu site upon nitrite binding during the catalytic reaction. The reduction potentials and pKa values calculated for the relevant protonation and reduction states show two possible routes, A and B. Reduction of the T2 Cu site in the resting state is followed by endothermic nitrite binding in route A, while exothermic nitrite binding occurs prior to reduction of the T2 Cu site in route B. We concluded that our results support the random-sequential mechanism rather than the ordered mechanism. PMID:27455866

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

    Science.gov (United States)

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

    2009-06-15

    A bacterial strain QZ2 was isolated from sludge of anoxic sulfide-oxidizing (ASO) reactor. Based on 16S rDNA sequence analysis and morphology, the isolate was identified as Ochrobactrum sp. QZ2. The strain was facultative chemolithotroph, able of using sulfide to reduce nitrite anaerobically. It produced either elemental sulfur or sulfate as the product of sulfide oxidation, depending on the initial sulfide and nitrite concentrations. The optimum growth pH and temperature for Ochrobactrum sp. QZ2 were found as 6.5-7.0 and 30 degrees C, respectively. The specific growth rate (micro) was found as 0.06 h(-1) with a doubling time of 19.75h; the growth seemed more sensitive to highly alkaline pH. Ochrobactrum sp. QZ2 catalyzed sulfide oxidation to sulfate was more sensitive to sulfide compared with nitrite as indicated by IC(50) values for sulfide and nitrite utilization implying that isolate was relatively more tolerant to nitrite. The comparison of physiology of Ochrobactrum sp. QZ2 with those of other known sulfide-oxidizing bacteria suggested that the present isolate resembled to Ochrobactrum anthropi in its denitrification ability. PMID:19010594

  19. Photodissociation of alkyl nitrites in a molecular beam. Primary and secondary reactions

    International Nuclear Information System (INIS)

    The translational energy distributions P(ET) for the 248-nm photodissociation products (NO + RO) of isopropyl nitrite and tert-butyl nitrite have been measured with a molecular beam time-of-flight (TOF) apparatus. Previous experiments with methyl nitrite and ethyl nitrite have been repeated with higher resolution. The average photofragment translational energies of these four alkyl nitrites are in good agreement with those predicted by an impulsive model that treats the NO as a rigid fragment and the alkoxy radical as a soft fragment. Hence, and in contrast to the vibrational predissociation on the S1 potential energy surface, S2 dissociation is direct and involves no significant vibrational-translational coupling between the reaction coordinate rO-N and the rNdouble-bondO coordinate. The width of the experimental P(ET) distributions decreases with increasing size of the alkoxy substituent. This result is discussed in terms of an anticorrelation between the internal energies of a fragment pair. Furthermore, the spontaneous secondary dissociation of isopropoxy and tert-butoxy photofragments was observed which yields CH3 radicals and acetaldehyde or acetone, respectively. The unimolecular decay of these alkoxy radicals confirms their relatively high internal energy as deduced from the primary P(ET) and it is shown that this decay occurs on a submicrosecond time scale

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

    Energy Technology Data Exchange (ETDEWEB)

    Mahmood, Qaisar, E-mail: mahmoodzju@gmail.com [Department of Environmental Engineering, Zhejiang University Hangzhou 310029 (China); Department of Environmental Sciences, COMSATS Institute of Information Technology Abbottabad (Pakistan); Hu Baolan; Cai Jing [Department of Environmental Engineering, Zhejiang University Hangzhou 310029 (China); Zheng Ping, E-mail: pzheng@zju.edu.cn [Department of Environmental Engineering, Zhejiang University Hangzhou 310029 (China); Azim, Muhammad Rashid [Department of Botany, Federal Government Post Graduate College H-8 Islamabad (Pakistan); Jilani, Ghulam [Department of Soil Science and Soil and Water Conservation, PMAS Arid Agriculture University, Rawalpindi (Pakistan); Islam, Ejazul [Department of Environmental Engineering, Zhejiang University Hangzhou 310029 (China)

    2009-06-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-08-28

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

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

    Science.gov (United States)

    Smith, Jacob W.; Lam, Royce K.; Shih, Orion; Rizzuto, Anthony M.; Prendergast, David; Saykally, Richard J.

    2015-08-01

    Nitrate and nitrite ions are of considerable interest, both for their widespread use in commercial and research contexts and because of their central role in the global nitrogen cycle. The chemistry of atmospheric aerosols, wherein nitrate is abundant, has been found to depend on the interfacial behavior of ionic species. The interfacial behavior of ions is determined largely by their hydration properties; consequently, the study of the hydration and interfacial behavior of nitrate and nitrite comprises a significant field of study. In this work, we describe the study of aqueous solutions of sodium nitrate and nitrite via X-ray absorption spectroscopy (XAS), interpreted in light of first-principles density functional theory electronic structure calculations. Experimental and calculated spectra of the nitrogen K-edge XA spectra of bulk solutions exhibit a large 3.7 eV shift between the XA spectra of nitrate and nitrite resulting from greater stabilization of the nitrogen 1s energy level in nitrate. A similar shift is not observed in the oxygen K-edge XA spectra of NO3- and NO2-. The hydration properties of nitrate and nitrite are found to be similar, with both anions exhibiting a similar propensity towards ion pairing.

  3. A sensitive fluorimetric method for determination of trace amounts of nitrite based on luminescence energy transfer

    Energy Technology Data Exchange (ETDEWEB)

    Wang Lun, E-mail: wanglun@mail.ahnu.edu.c [Anhui Key Laboratory of Chemo-Biosensing, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000 (China); Chen Jingguo; Chen Hongqi; Zhou Cailing; Ling Bo; Fu Jie [Anhui Key Laboratory of Chemo-Biosensing, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000 (China)

    2011-01-15

    An efficient luminescence energy transfer (LET) system based on terbium(III)-sodium hexametaphosphate (Tb/SHMP) chelates as donor and 4-((4-(2-aminoethylamino)naphthalen-1-yl)diazenyl)benzenesulfonic acid dihydrochloride (ANDBS) as acceptor was developed for sensitive determination of trace nitrite. Stable and strong fluorescence Tb/SHMP chelates were prepared in aqueous solution. Based on Griess Reaction, ANDBS was generated by the quantitative reaction of nitrite, sulfanilamide and N-(1-naphtyl)-ethylenediamine dihydrochloride (N1NED). The degree of the overlap was effective for LET between the emission spectrum of Tb/SHMP chelates and the absorption spectrum of ANDBS. Based on the luminescence intensity quenching of Tb/SHMP chelates in proportion to the trace amounts of nitrite, a new assay for the selective and sensitive determination of nitrite was developed. Under the optimum conditions, the linear calibration graph was obtained with a linear range of 0.00040-0.20 {mu}g mL{sup -1} (R=0.99657). The detection limit of NO{sub 2}{sup -} was 0.00010 {mu}g mL{sup -1} (R=0.99657). The method was applied successfully to the determination of nitrite for synthetic samples.

  4. Carbonic anhydrases are producers of S-nitrosothiols from inorganic nitrite and modulators of soluble guanylyl cyclase in human platelets.

    Science.gov (United States)

    Hanff, Erik; Böhmer, Anke; Zinke, Maximilian; Gambaryan, Stepan; Schwarz, Alexandra; Supuran, Claudiu T; Tsikas, Dimitrios

    2016-07-01

    Nitric oxide (NO), S-nitrosoglutathione (GSNO) and S-nitrosocysteine are highly potent signaling molecules, acting both by cGMP-dependent and cGMP-independent mechanisms. The NO metabolite nitrite (NO2 (-)) is a major NO reservoir. Hemoglobin, xanthine oxidoreductase and carbonic anhydrase (CA) have been reported to reduce/convert nitrite to NO. We evaluated the role and the physiological importance of CA for an extra-platelet CA/nitrite/NO/cGMP pathway in human platelets. Authentic NO was analyzed by an NO-sensitive electrode. GSNO and GS(15)NO were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). cGMP was determined by LC-MS/MS or RIA. In reduced glutathione (GSH) containing aqueous buffer (pH 7.4), human and bovine erythrocytic CAII-mediated formation of GSNO from nitrite and GS(15)NO from (15)N-nitrite. In the presence of L-cysteine and GSH, this reaction was accompanied by NO release. Incubation of nitrite with bovine erythrocytic CAII and recombinant soluble guanylyl cyclase resulted in cGMP formation. Upon incubation of nitrite with bovine erythrocytic CAII and washed human platelets, cGMP and P-VASP(S239) were formed in the platelets. This study provides the first evidence that extra-platelet nitrite and erythrocytic CAII may modulate platelet function in a cGMP-dependent manner. The new nitrite-dependent CA activity may be a general principle and explain the cardioprotective effects of inorganic nitrite in the vasculature. We propose that nitrous acid (ONOH) is the primary CA-catalyzed reaction product of nitrite. PMID:27129464

  5. Nitric oxide availability in deeply hypoxic crucian carp: acute and chronic changes and utilization of ambient nitrite reservoirs.

    Science.gov (United States)

    Hansen, Marie N; Gerber, Lucie; Jensen, Frank B

    2016-03-15

    Recent research suggest that anoxia-tolerant fish transfer extracellular nitrite into the tissues, where it is used for nitric oxide (NO) generation, iron-nitrosylation, and S-nitrosation of proteins, as part of the cytoprotective response toward prolonged hypoxia and subsequent reoxygenation. We hypothesized that crucian carp take up ambient nitrite and use it as a source of cellular NO availability during hypoxia. Fish were exposed for 1 day to normoxia (Po2 > 140 mmHg) and deep hypoxia (1 < Po2 < 3 mmHg) at both low (< 0.2 μM) and moderately elevated (10 μM) ambient [nitrite] to decipher NO metabolites in plasma and several tissues. We also compared NO metabolite changes during acute (10 min) and chronic (1 day) exposures to three different O2 levels. Plasma [nitrite] decreased with decreasing [O2], while the cellular concentrations of nitrite and nitros(yl)ated compounds either increased or stayed constant, depending on O2 level and tissue type. Nitrite was notably increased in the heart during deep hypoxia, and the increase was amplified by elevated ambient [nitrite]. Raised nitrite also increased gill [nitrite] and decreased mRNA expression of an inducible nitric oxide synthase-2 gene variant. The data support that ambient nitrite is taken up across the gills to be distributed via the blood to the tissues, particularly the heart, where it assists in cytoprotection and other functions. Cardiac nitrite was not elevated in acutely exposed fish, revealing that the response requires time. NO metabolite levels were higher during acute than chronic exposures, possibly caused by increased swimming activity and stress in acutely exposed fish. PMID:26764058

  6. INCREASED CONCENTRATION OF NITRITE IN SYNOVIAL FLUID AND SERUM SAMPLES IN STEROID INDUCED FEMORAL HEAD NECROSIS

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    To investigate the role of nitric oxide (NO) in steroid-induced femoral head necrosis, NO production was measured indirectly as nitrite in serum and synovial fluid samples from patients with steroid-induced femoral head necrosis together with serum samples from healthy volunteers matched for age and sex. The results showed that:① serum nitrite concentration in patients with femoral head necrosis were significantly lower than that in controls (P<0.001); ② nitrite level of synovial fluid was markedly higher than that of serum. In addition, there was a positive correlation between them (r=0.378,P<0.05). We reach the conclusion:① NO is synthesized by synovium and chondrocytes; ② the decreased NO concentration in serum suggests a protective role in steroid-induced femoral head necrosis.

  7. Study on the Corrosion Inhibition Characteristics of Carbon Steel by Sodium Phosphate and Sodium Nitrite

    International Nuclear Information System (INIS)

    Sodium nitrite is widely used as one of the popular corrosion inhibitors for the protection of ferrous metal in closed cooling water system, such as a diesel engine and a chiller. The optimum treatment conditions are studied through laboratory tests using linear polarization resistance (LPR) technique. Corrosion rate of the carbon steel electrode could be maintained less than 2.5x10-3 mmpy in the test condition of 500 ppm as NO2-, 200 ppm as CT, 70 .deg. C and pH 6.8. The pH control is confirmed not to be an important factor in the protection of carbon steel by sodium nitrite inhibitor. The addition of tolyltriazole was needed for the protection of the copper alloy in the sodium nitrite treatment system

  8. Effect of temperature and type of packages on nitrates and nitrites content in lettuce

    Directory of Open Access Journals (Sweden)

    Józef Bąkowski

    2013-12-01

    Full Text Available Lettuce wrapped in unperforated PE film, perforated PE film, stretch film and without wrapping was stored at 1, 6, 20 and 28°C. Freshly harvested lettuce and after one day of storage, independently on storage conditions, did not contains nitrites„ During storage of lettuce at 1°C only one time small quantities of nitrites (4.3 mg NO2/kg fresh matter were found - after twelve days storage in perforated PE film. Storage of lettuce longer than 7 days at 6°C caused formation of nitrites. Lettuce stored at 20 and 28°C in unperforated PE film contained nitrites already after 2 or 3 days of storage. Decline of nitrates during storage of lettuce was independent from film used to wrapping.

  9. Fruit Calcium: Transport and Physiology

    Science.gov (United States)

    Hocking, Bradleigh; Tyerman, Stephen D.; Burton, Rachel A.; Gilliham, Matthew

    2016-01-01

    Calcium has well-documented roles in plant signaling, water relations and cell wall interactions. Significant research into how calcium impacts these individual processes in various tissues has been carried out; however, the influence of calcium on fruit ripening has not been thoroughly explored. Here, we review the current state of knowledge on how calcium may impact the development, physical traits and disease susceptibility of fruit through facilitating developmental and stress response signaling, stabilizing membranes, influencing water relations and modifying cell wall properties through cross-linking of de-esterified pectins. We explore the involvement of calcium in hormone signaling integral to the physiological mechanisms behind common disorders that have been associated with fruit calcium deficiency (e.g., blossom end rot in tomatoes or bitter pit in apples). This review works toward an improved understanding of how the many roles of calcium interact to influence fruit ripening, and proposes future research directions to fill knowledge gaps. Specifically, we focus mostly on grapes and present a model that integrates existing knowledge around these various functions of calcium in fruit, which provides a basis for understanding the physiological impacts of sub-optimal calcium nutrition in grapes. Calcium accumulation and distribution in fruit is shown to be highly dependent on water delivery and cell wall interactions in the apoplasm. Localized calcium deficiencies observed in particular species or varieties can result from differences in xylem morphology, fruit water relations and pectin composition, and can cause leaky membranes, irregular cell wall softening, impaired hormonal signaling and aberrant fruit development. We propose that the role of apoplasmic calcium-pectin crosslinking, particularly in the xylem, is an understudied area that may have a key influence on fruit water relations. Furthermore, we believe that improved knowledge of the calcium

  10. Fruit Calcium: Transport and Physiology.

    Science.gov (United States)

    Hocking, Bradleigh; Tyerman, Stephen D; Burton, Rachel A; Gilliham, Matthew

    2016-01-01

    Calcium has well-documented roles in plant signaling, water relations and cell wall interactions. Significant research into how calcium impacts these individual processes in various tissues has been carried out; however, the influence of calcium on fruit ripening has not been thoroughly explored. Here, we review the current state of knowledge on how calcium may impact the development, physical traits and disease susceptibility of fruit through facilitating developmental and stress response signaling, stabilizing membranes, influencing water relations and modifying cell wall properties through cross-linking of de-esterified pectins. We explore the involvement of calcium in hormone signaling integral to the physiological mechanisms behind common disorders that have been associated with fruit calcium deficiency (e.g., blossom end rot in tomatoes or bitter pit in apples). This review works toward an improved understanding of how the many roles of calcium interact to influence fruit ripening, and proposes future research directions to fill knowledge gaps. Specifically, we focus mostly on grapes and present a model that integrates existing knowledge around these various functions of calcium in fruit, which provides a basis for understanding the physiological impacts of sub-optimal calcium nutrition in grapes. Calcium accumulation and distribution in fruit is shown to be highly dependent on water delivery and cell wall interactions in the apoplasm. Localized calcium deficiencies observed in particular species or varieties can result from differences in xylem morphology, fruit water relations and pectin composition, and can cause leaky membranes, irregular cell wall softening, impaired hormonal signaling and aberrant fruit development. We propose that the role of apoplasmic calcium-pectin crosslinking, particularly in the xylem, is an understudied area that may have a key influence on fruit water relations. Furthermore, we believe that improved knowledge of the calcium

  11. Calcium and calcitonin responses to calcium infusion in type I diabetes mellitus.

    OpenAIRE

    Amado, J. A.; C. Gomez; Obaya, S.; Otero, M; Gonzalez-Macias, J

    1987-01-01

    We studied calcium and calcium and calcitonin responses to intravenous calcium infusion (3 mg of elemental calcium/kg of body weight in 10 minutes) in 21 type I diabetic males and 17 age-matched normal males. Baseline total calcium, parathyroid hormone and calcitonin levels were normal in the diabetic group, but ionized calcium was lowered. Cortical bone status and osteocalcin levels were normal, suggesting a normal osteoblastic function. Total calcium and ionized calcium responses to calcium...

  12. 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.

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

    International Nuclear Information System (INIS)

    Highlights: ► Nitrite increased photo-toxicity of nano-TiO2 on human keratinocyte cells in a dose-dependant manner. ► Morphological study suggested the cell death may be mediated by apoptosis inducing factor. ► Protein nitration was generated in the cells, and the most abundant nitrated protein was identified as cystatin-A. ► Tyr35 was the most likely site to be nitrated in cystatin-A. -- Abstract: Our previous work found that in the presence of nitrite, titanium dioxide nanoparticles can cause protein tyrosine nitration under UVA irradiation in vivo. In this paper, the human keratinocyte cells was used as a skin cell model to further study the photo-toxicity of titanium dioxide nanoparticles when nitrite was present. The results showed that nitrite increased the photo-toxicity of titanium dioxide in a dose-dependant manner, and generated protein tyrosine nitration in keratinocyte cells. Morphological study of keratinocyte cells suggested a specific apoptosis mediated by apoptosis inducing factor. It was also found the main target nitrated in cells was cystatin-A, which expressed abundantly in cytoplasm and functioned as a cysteine protease inhibitor. The stress induced by titanium dioxide with nitrite under UVA irradiation in human keratinocyte cells appeared to trigger the apoptosis inducing factor mediated cell death and lose the inhibition of active caspase by cystatin-A. We conclude that nitrite can bring new damage and stress to human keratinocyte cells with titanium dioxide nanoparticles under UVA irradiation.

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

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

  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. Kinetics of the reduction of nitrite oil by sulfur dioxide in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Oblath, S.B.

    1981-08-01

    Reactions between nitrite and bisulfite ions in aqueous solutions were studied in which sulfur (IV) species are oxidized to sulfate ions and nitrogen (III) species are reduced. The dependence on temperature, ionic strength, acidity, and solution composition was determined. The actual products formed depend primarily on the concentration of bisulfite ion. The importance of these reactions to atmospheric aerosol formation processes is discussed. Under most conditions, the nitrogen product is hydroxylamine-N, N-disulfonate. Two processes are responsible for its formation. The first process (when the bisulfite concentration is greater than 0.1 M) is first order in nitrite ion, second order in bisulfite ion, and independent of acidity and temperature. It has a strong dependence on the ionic strength. The second and dominant process contributes to the product formation under all conditions and is first order in nitrite, bisulfite, and hydrogen ions. This process is independent of ionic strength and has a 12 kcal/mole activation energy. Both processes are insensitive to the choice of buffer. Whenever the hydrogen ion concentraion is nearly equal to that of the bisulfite ion, nitrous oxide is also a product. A mechanism is proposed to account for these results. It consists of a direct reaction of nitrite ion with metabisulfite ion to form hydroxylamine disulfonate, in parallel with a reaction between nitrous acid and bisulfite ion to form nitrososulfonic acid. This rapidly adds a bisulfite ion to form hydroxylamine disulfonate or undergoes hydrolysis to form nitrous oxide. The reaction between nitrite ion and hydroxylamine-N-sulfonate to produce nitrous oxide was also investigated. The reaction is first order in nitrite ion, second order in hydrogen ion, and between zero and first order in hydroxylamine monosulfonate, depending on the concentration.

  18. PRELIMINARY STUDY ON GROUNDWATER POLLUTION WITH NITRITES AND NITRATES IN GĂTAIA (TIMIŞ COUNTY

    Directory of Open Access Journals (Sweden)

    Rodica TÖRÖK-OANCE

    2013-12-01

    Full Text Available Nitrate pollution of water is a widespread issue. This study analyses the pollution with nitrites and nitrates in wells from Gătaia. We collected water samples from 17 wells. The nitrites and nitrates content was determined by the photometric method, using the Spectroquant NOVA60 photometer. We analysed following factors impacting pollution: manure deposits, latrines, livestock farms, slope and depth of the groundwater level in wells. The distances between wells and the analysed pollution sources as well as the slope were determined in ArcGIS 9.3. Software. The statistical analysis has been performed in Excel and GraphPad InStat. The maximum admissible concentration of nitrates has been exceeded in 41.17% of the water samples, and the maximum admissible concentration of nitrites in 11.76% of the water samples. Both simple and multiple regressions (with 2 to 5 independent variables have been performed in order to analyse the relationship between nitrites concentration, respectively nitrates concentration in water and the factors impacting pollution. The simple linear regression could explain to a very small extent this relationship but it was explained to a greater extent by multiple regression. As more factors impacting pollution have been taken into consideration as independent variables, the correlation coefficient between the nitrites content, respectively nitrates, in water and these factors increased. The greatest correlation coefficient (0.6079 with p significant (0.0419 was obtained in case of multiple regression with all 5 independent variables, the dependent variable being the nitrite concentration.

  19. 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

  20. 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.

  1. Autotrophic nitrogen removal from black water: calcium addition as a requirement for settleability.

    Science.gov (United States)

    de Graaff, M S; Temmink, H; Zeeman, G; van Loosdrecht, M C M; Buisman, C J N

    2011-01-01

    Black (toilet) water contains half of the organic load in the domestic wastewater, as well as the major fraction of the nutrients nitrogen and phosphorus. When collected with vacuum toilets, the black water is 25 times more concentrated than the total domestic wastewater stream, i.e. including grey water produced by laundry, showers etc. A two-stage nitritation-anammox process was successfully employed and removed 85%-89% of total nitrogen in anaerobically treated black water. The (free) calcium concentration in black water was too low (42 mg/L) to obtain sufficient granulation of anammox biomass. The granulation and retention of the biomass was improved considerably by the addition of 39 mg/L of extra calcium. This resulted in a volumetric nitrogen removal rate of 0.5 gN/L/d, irrespective of the two temperatures of 35 °C and 25 °C at which the anammox reactors were operated. Nitrous oxide, a very strong global warming gas, was produced in situations of an incomplete anammox conversion accompanied by elevated levels of nitrite. PMID:20822793

  2. 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...

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

    Directory of Open Access Journals (Sweden)

    Natia Qipshidze-Kelm

    2014-01-01

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

  4. The production of nitrite from radiolytic, photolytic and electrolytic degradation of metronidazole

    International Nuclear Information System (INIS)

    Gamma and U.V.-irradiation studies and electrolysis studies of metronidazole in aqueous media have been carried out in order to investigate the mechanism of action of metronidazole as radiosensitizer of hypoxic cells and its selective cytotoxicity. The results obtained show that besides the generally assumed mechanism of reduction leading to nitroso and hydroxylamine derivatives, an alternative route, involving the production of nitrite ions, must be taken into account. The proposed mechanism attributes the nitrite ion production to a decay reaction of metronidazole radical anions. (author)

  5. Nitrates et nitrites : Polluants qui menacent la santé et l’environnement

    OpenAIRE

    Laila IDRISSI

    2006-01-01

    Les nitrites et les nitrates sont des substances chimiques naturelles qui entrent dans le cycle de l’azote. Ce dernier est consommé par les plantes sous forme de nitrates qui correspond au minéral le plus fréquent dans les eaux. Les nitrates sont beaucoup utilisés dans les engrais inorganiques et les explosifs, comme agents de conservation des aliments et comme substances chimiques brutes dans divers procédés industriels. Les nitrites servent surtout d’agents de conservation des aliments, en ...

  6. The nasFEDCBA operon for nitrate and nitrite assimilation in Klebsiella pneumoniae M5al.

    OpenAIRE

    Lin, J. T.; Goldman, B. S.; Stewart, V

    1994-01-01

    Klebsiella pneumoniae can use nitrate and nitrite as sole nitrogen sources through the nitrate assimilation pathway. We previously identified structural genes for assimilatory nitrate and nitrite reductases, nasA and nasB, respectively. We report here our further identification of four genes, nasFEDC, upstream of the nasBA genes. The nasFEDCBA genes probably form an operon. Mutational and complementation analyses indicated that both the nasC and nasA genes are required for nitrate assimilatio...

  7. Enhancement of Nitrite Reduction Kinetics on Electrospun Pd-Carbon Nanomaterial Catalysts for Water Purification.

    Science.gov (United States)

    Ye, Tao; Durkin, David P; Hu, Maocong; Wang, Xianqin; Banek, Nathan A; Wagner, Michael J; Shuai, Danmeng

    2016-07-20

    We report a facile synthesis method for carbon nanofiber (CNF) supported Pd catalysts via one-pot electrospinning and their application for nitrite hydrogenation. A mixture of Pd acetylacetonate (Pd(acac)2), polyacrylonitrile (PAN), and nonfunctionalized multiwalled carbon nanotubes (MWCNTs) was electrospun and thermally treated to produce Pd/CNF-MWCNT catalysts. The addition of MWCNTs with a mass loading of 1.0-2.5 wt % (to PAN) significantly improved nitrite reduction activity compared to the catalyst without MWCNT addition. The results of CO chemisorption confirmed that the addition of MWCNTs increased Pd exposure on CNFs and hence improved catalytic activity. PMID:27387354

  8. Cultivation of a novel cold-adapted nitrite oxidizing betaproteobacterium from the Siberian Arctic

    OpenAIRE

    Alawi, Mashal; Lipski, André; Sanders, Tina; Pfeiffer, Eva-Maria; Spieck, Eva

    2007-01-01

    Permafrost-affected soils of the Siberian Arctic were investigated with regard to identification of nitrite oxidizing bacteria active at low temperature. Analysis of the fatty acid profiles of enrichment cultures grown at 4°C, 10°C and 17°C revealed a pattern that was different from that of known nitrite oxidizers but was similar to fatty acid profiles of Betaproteobacteria. Electron microscopy of two enrichment cultures grown at 10°C showed prevalent cells with a conspicuous ultrastructure. ...

  9. Ultra-trace analysis of nitrite in food samples by flow injection with spectrophotometric detection

    Energy Technology Data Exchange (ETDEWEB)

    Ensafi, A.A.; Bagherian Dehaghei, G. [College of Chemistry, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of)

    1999-01-01

    A flow injection system with spectrophotometric detection is proposed for the determination of low levels of nitrite based on its catalytic effect on the oxidation of gallocyanine by bromate in acidic media. Various analytical parameters such as acidity, reagent concentration, flow rate, sample size, time, temperature, and interfering species were studied. The calibration graph was linear for 0.020-0.500 {mu}g/mL of nitrite. The method is successfully applied to food samples. Up to 30 {+-} 5 samples can be analyzed per hour. (orig.) With 3 figs., 3 tabs., 17 refs.

  10. Aeration Strategies To Mitigate Nitrous Oxide Emissions from Single-Stage Nitritation/Anammox Reactors

    DEFF Research Database (Denmark)

    Domingo Felez, Carlos; Mutlu, A. Gizem; Jensen, Marlene Mark;

    2014-01-01

    -stage nitritation/anammox were operated under different aeration strategies, gradually adjusted over six months. At constant but limiting oxygen loading, synthetic reject water was fed (0.75g-N/L.d) and high nitrogen removal efficiencies (83 +/- 5 and 88 +/- 2%) obtained. Dynamics of liquid phase nitrous (N2O) and...... conditions where anaerobic exceeds aerobic ammonium oxidation activity is proposed to minimize N2O emissions from single-stage nitritation/anammox reactors; increasing the frequency of aeration cycling is an efficient way of obtaining those conditions....

  11. Effect of temperature and type of packages on nitrates and nitrites content in lettuce

    OpenAIRE

    Józef Bąkowski; Helena Michalik; Marcin Horbowicz

    2013-01-01

    Lettuce wrapped in unperforated PE film, perforated PE film, stretch film and without wrapping was stored at 1, 6, 20 and 28°C. Freshly harvested lettuce and after one day of storage, independently on storage conditions, did not contains nitrites„ During storage of lettuce at 1°C only one time small quantities of nitrites (4.3 mg NO2/kg fresh matter) were found - after twelve days storage in perforated PE film. Storage of lettuce longer than 7 days at 6°C caused formation of nitrites. Lettuc...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-04-01

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

  13. 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. PMID:23771179

  14. 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. PMID:27010349

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-11-30

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

  16. 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.

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

    NARCIS (Netherlands)

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

    2007-01-01

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

  18. 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.

    1994-01-01

    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 nitr

  19. 78 FR 69646 - Sodium Nitrite From the People's Republic of China: Final Results of the Expedited First Sunset...

    Science.gov (United States)

    2013-11-20

    ...-Year (``Sunset'') Reviews, 78 FR 39256 (July 1, 2013); see also Sodium Nitrite from the People's Republic of China: Countervailing Duty Order, 73 FR 50595 (August 27, 2008) (``CVD Order''). As explained... International Trade Administration Sodium Nitrite From the People's Republic of China: Final Results of...

  20. Photolysis of n-butyl nitrite and isoamyl nitrite at 355 nm: A time-resolved Fourier transform infrared emission spectroscopy and ab initio study

    CERN Document Server

    Ji, Min; Zhang, Qun; Chen, Yang

    2009-01-01

    We report on the photodissociation dynamics study of n-butyl nitrite (n-C_4H_9ONO) and isoamyl nitrite ((CH_3)_2C_3H_5ONO) by means of time-resolved Fourier transform infrared (TR-FTIR) emission spectroscopy. The obtained TR-FTIR emission spectra of the nascent NO fragments produced in the 355-nm laser photolysis of the two alkyl nitrite species showed an almost identical rotational temperature and vibrational distributions of NO. In addition, a close resemblance between the two species was also found in the measured temporal profiles of the IR emission of NO and the recorded UV absorption spectra. The experimental results are consistent with our ab initio calculations using the time-dependent density functional theory at the B3LYP/6-311G(d,p) level, which indicate that the substitution of one of the two {gamma}-H atoms in n-C_4H_9ONO with a methyl group to form (CH_3)_2C_3H_5ONO has only a minor effect on the photodissociation dynamics of the two molecules.

  1. Reverse calcium affinity purification of Fab with calcium derivatized hydroxyapatite

    OpenAIRE

    Gagnon, Pete; Cheung, Chia-wei; Yazaki, Paul J.

    2009-01-01

    This study introduces the application of calcium-derivatized hydroxyapatite for purification of Fab. Fab binds to native hydroxyapatite but fails to bind to the calcium derivatized form. IgG, Fc, and most other protein contaminants bind to the calcium form. This supports Fab purification by a simple flow-through method that achieves greater than 95% purity from papain digests and mammalian cell culture supernatants. Alternatively, Fab can be concentrated on native hydroxyapatite then eluted s...

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

    DEFF Research Database (Denmark)

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

    Combining partial nitritation with anaerobic ammonium oxidation maybe a cost- and energy-efficient alternative to remove reduced nitrogen from nitrogen rich waste streams. However, increased N2O emissions (upto several % of the incoming N flux) have been observed for reactors performing partial...... nitritation, which is likely due to the stimulatory effect of combined elevated nitrite and ammonium concentrations and reduced oxygen concentrations on nitrous oxide formation by ammonium oxidizing bacteria. Because increased N2O emission may be inherent to partial nitrification systems, we have explored how...... converted ammonium N. Anoxic batch incubations with biofilm samples revealed a significant N2O assimilatory activity. Anoxic incubations with N-15 enriched nitrite, nitrate, or ammonium, in presence or absence of acetate revealed the following: a very high conversion of original nitrite or nitrate N to N2O...

  3. Glycochenodeoxycholic acid inhibits calcium phosphate precipitation in vitro by preventing the transformation of amorphous calcium phosphate to calcium hydroxyapatite.

    OpenAIRE

    Qiu, S M; Wen, G.; Hirakawa, N; Soloway, R D; Hong, N K; Crowther, R S

    1991-01-01

    Calcium hydroxyapatite can be a significant component of black pigment gallstones. Diverse molecules that bind calcium phosphate inhibit hydroxyapatite precipitation. Because glycine-conjugated bile acids, but not their taurine counterparts, bind calcium phosphate, we studied whether glycochenodeoxycholic acid inhibits calcium hydroxyapatite formation. Glycochenodeoxycholic acid (2 mM) totally inhibited transformation of amorphous calcium phosphate microprecipitates to macroscopic crystalline...

  4. Progressive effects of nigella sativa agaiast the interaction of sodium nitrite and sun - set yellow in albino rats

    Directory of Open Access Journals (Sweden)

    Eman G.E. Helal * Samir A.M. Zaahkouk

    2003-03-01

    Full Text Available It has been noticed that kids usually eat and drink food containing food preservator and food colorants at the same time. This behavior has been attracted the attention to study the interaction between one of food preservatives ( sodium nitrite NaNO3 and one of bood colorants (sunset -yellow S.S.Yellow. The interaction of the limited dose of these two components resulted in a lethal dose. So, 1/10 of this dose was used for 30 days and left for another 15 days post the last dose for recovery. Other group was supplemented with Nigella sativa ( N.S oil in addition to the same mixture. Ingestion of (NaNO3 and S.S.Yellow mixture significantly decreased rat's body weight, RBC and WBC counts, Hb%, Hct%, serum inorganic phosphorus, serum protein and serum albumin. Significant increases were observed in serum glucose, T3, T4, calcium, -GT, LDH, CPK, Alk.ph and cholesterol. Also cholesterol of brain, liver and heart were significantly elevated. No changes were recorded for; organ/body weight, respiratory rate, heart beats, rectal temperature, acid phosphatase activity, AST and ALT activities of serum and tissues, protein of tissues, serum globulin, and total lipids of serum and tissues, cholesterol of muscle and kidney and serum triglyarides. A complete recovery of most biochemical and haematological parameters was observed days after stoppage of the mixture or after administration of Nigella sativa oil. This study ringe bells of dangerous. The study showed also that even the permitted colourants and food preservatives when taken together or if taken in excessive quantity may be harmful. Therefore, provision should be made for quantities estimation of food additives in various food stuff.

  5. Achieving the nitrite pathway using FA inhibition and process control in UASB-SBR system removing nitrogen from landfill leachate

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    An up-flow sludge blanket(UASB) and sequencing batch reactor(SBR) system was introduced to remove organics and nitrogen from landfill leachate.The synergetic effect of free ammonia(FA) inhibition and process control was used to achieve the nitrite pathway in the SBR.In previous research,inhibition of FA on nitrite oxidizing bacteria(NOB) activity has been revealed and the process control parameters(DO,ORP and pH) exactly indicate the end-point of nitritation.The method was implemented in the SBR achieving stable nitrogen removal via the nitrite pathway from landfill leachate.The degree of nitrite accumulation during the nitritation was monitored along with the simultaneous and advanced removal of organics and nitrogen in the UASB-SBR system.The nitrifying bacteria community was quantitatively analyzed by fluorescence in situ hybridization(FISH) techniques.Batch tests were carried out to investigate the denitritation kinetics of microbial bacteria in the SBR.Experimental results showed that the nitrite pathway could be repeatedly and reliably achieved by synergetic effect of FA inhibition and process control.FISH analysis showed the dominant nitrifying bacteria were ammonia-oxidizing β-Proteobacteria. Relationship between nitrite concentration and nitrite reduction rate followed the Monod-type equation.The maximum specific nitrite utilization rate(k) and half-velocity constant(Ks) were calculated as 0.44 gN gVSS-1d-1and 15.8 mg L-1,respectively.

  6. Calcium – how and why?

    Indian Academy of Sciences (India)

    J K Jaiswal

    2001-09-01

    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 that during the origin and early evolution of life the Ca2+ ion was given a unique opportunity to be used in several biological processes because of its unusual physical and chemical properties.

  7. Calcium addition in straw gasification

    DEFF Research Database (Denmark)

    Risnes, H.; Fjellerup, Jan Søren; Henriksen, Ulrik Birk; Moilanen, A.; Norby, P.; Papadakis, K.; Posselt, D.; Sørensen, L. H.

    2003-01-01

    The present work focuses on the influence of calcium addition in gasification. The inorganic¿organic element interaction as well as the detailed inorganic¿inorganic elements interaction has been studied. The effect of calcium addition as calcium sugar/molasses solutions to straw significantly...... affected the ash chemistry and the ash sintering tendency but much less the char reactivity. Thermo balance test are made and high-temperature X-ray diffraction measurements are performed, the experimental results indicate that with calcium addition major inorganic¿inorganic reactions take place very late...

  8. Calcium Phosphate Biomaterials: An Update

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Current calcium phosphate (CaP) biomaterials for bone repair, substitution, augmentation and regeneration include hydroxyapatite ( HA ) from synthetic or biologic origin, beta-tricalcium phosphate ( β-TCP ) , biphasic calcium phosphate (BCP), and are available as granules, porous blocks, components of composites (CaP/polymer) cements, and as coatings on orthopedic and dental implants. Experimental calcium phosphate biomaterials include CO3- and F-substituted apatites, Mg-and Zn-substituted β-TCP, calcium phosphate glasses. This paper is a brief review of the different types of CaP biomaterials and their properties such as bioactivity, osteoconductivity, osteoinductivity.

  9. Nonthermal effect of microwave irradiation on nitrite uptake in Chlamydomonas reinhardtii

    International Nuclear Information System (INIS)

    When cells of the unicellular green alga Chlamydomonas reinhardtii were subjected to microwave irradiation at 2.45 GHz, nitrite uptake kinetics still obeyed the Michaelis-Menten equation, the Km of the process remaining constant, whereas V max increased, which indicates an enhanced nonthermal permeability in irradiated cells. (author)

  10. Anaerobic Oxidation of Methane Coupled to Nitrite Reduction by Halophilic Marine NC10 Bacteria.

    Science.gov (United States)

    He, Zhanfei; Geng, Sha; Cai, Chaoyang; Liu, Shuai; Liu, Yan; Pan, Yawei; Lou, Liping; Zheng, Ping; Xu, Xinhua; Hu, Baolan

    2015-08-15

    Anaerobic oxidation of methane (AOM) coupled to nitrite reduction is a novel AOM process that is mediated by denitrifying methanotrophs. To date, enrichments of these denitrifying methanotrophs have been confined to freshwater systems; however, the recent findings of 16S rRNA and pmoA gene sequences in marine sediments suggest a possible occurrence of AOM coupled to nitrite reduction in marine systems. In this research, a marine denitrifying methanotrophic culture was obtained after 20 months of enrichment. Activity testing and quantitative PCR (qPCR) analysis were then conducted and showed that the methane oxidation activity and the number of NC10 bacteria increased correlatively during the enrichment period. 16S rRNA gene sequencing indicated that only bacteria in group A of the NC10 phylum were enriched and responsible for the resulting methane oxidation activity, although a diverse community of NC10 bacteria was harbored in the inoculum. Fluorescence in situ hybridization showed that NC10 bacteria were dominant in the enrichment culture after 20 months. The effect of salinity on the marine denitrifying methanotrophic culture was investigated, and the apparent optimal salinity was 20.5‰, which suggested that halophilic bacterial AOM coupled to nitrite reduction was obtained. Moreover, the apparent substrate affinity coefficients of the halophilic denitrifying methanotrophs were determined to be 9.8 ± 2.2 μM for methane and 8.7 ± 1.5 μM for nitrite. PMID:26048927

  11. Synthesis and isotope-ratio analysis of methyl nitrite-15N

    International Nuclear Information System (INIS)

    Methyl nitrite-15N was synthesised on a 0.1 mole scale by the esterification of methanol by aqueous H15NO2. The method is simple and efficient, and provides analytically pure CH3O15NO. A method for determining the 15N enrichment of CH3O15NO is described. (author)

  12. Interdependence of two NarK domains in a fused nitrate/nitrite transporter.

    Science.gov (United States)

    Goddard, Alan D; Moir, James W B; Richardson, David J; Ferguson, Stuart J

    2008-11-01

    Nitrate uptake is essential for various bacterial processes and combines with nitrite export to form the usual initial steps of denitrification, a process that reduces nitrate to dinitrogen gas. Although many bacterial species contain NarK-like transporters that are proposed to function as either nitrate/proton symporters or nitrate/nitrite antiporters based on sequence homology, these transporters remain, in general, poorly characterized. Several bacteria appear to contain a transporter that is a fusion of two NarK-like proteins, although the significance of this arrangement remains elusive. We demonstrate that NarK from Paracoccus denitrificans is expressed as a fusion of two NarK-like transporters. NarK1 and NarK2 are separately capable of supporting anaerobic denitrifying growth but with growth defects that are partially mitigated by coexpression of the two domains. NarK1 appears to be a nitrate/proton symporter with high affinity for nitrate and NarK2 a nitrate/nitrite antiporter with lower affinity for nitrate. Each transporter requires two conserved arginine residues for activity. A transporter consisting of inactivated NarK1 fused to active NarK2 has a dramatically increased affinity for nitrate compared with NarK2 alone, implying a functional interaction between the two domains. A potential model for nitrate and nitrite transport in P. denitrificans is proposed. PMID:18823285

  13. Tetrazine-based chemistry for nitrite determination in a paper microfluidic device.

    Science.gov (United States)

    Ortiz-Gomez, Inmaculada; Ortega-Muñoz, Mariano; Salinas-Castillo, Alfonso; Álvarez-Bermejo, José Antonio; Ariza-Avidad, Maria; de Orbe-Payá, Ignacio; Santoyo-Gonzalez, Francisco; Capitan-Vallvey, Luis Fermin

    2016-11-01

    We present a new chemistry to determine nitrites implemented in a microfluidic paper-based analytical device (µPAD). The device is fabricated in cellulose paper with a sample reception area and three replicate detection areas with recognition chemistry immobilized by adsorption. The method involves the use of nitrite in an acid medium reaction to generate nitrous acid, which produces the oxidation of s-dihydrotetrazine: 1,2-dihydro-3,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetrazine (DHBPTz), which change the detection zone from colorless to pink. We used a digital camera and smartphone for the quantitative analysis of nitrite with the color coordinate S of the HSV color space as the analytical parameter. Parameters such as concentration and volume of s-dihydrotetrazine, pH, sample volume and reaction time were studied. The detection limit for this method is 1.30µM nitrite. To estimate the selectivity of the method an interference study of common ions in water samples was performed. The procedure was applied to natural water and compared with reference procedures. PMID:27591668

  14. Molecular Underpinnings of Nitrite Effect on CymA-Dependent Respiration in Shewanella oneidensis

    Science.gov (United States)

    Jin, Miao; Fu, Huihui; Yin, Jianhua; Yuan, Jie; Gao, Haichun

    2016-01-01

    Shewanella exhibit a remarkable versatility of respiration, with a diverse array of electron acceptors (EAs). In environments where these bacteria thrive, multiple EAs are usually present. However, we know little about strategies by which these EAs and their interaction affect ecophysiology of Shewanella. In this study, we demonstrate in the model strain, Shewanella oneidensis MR-1, that nitrite, not through nitric oxide to which it may convert, inhibits respiration of fumarate, and probably many other EAs whose reduction depends on quinol dehydrogenase CymA. This is achieved via the repression of cyclic adenosine monophosphate (cAMP) production, a second messenger required for activation of cAMP-receptor protein (Crp) which plays a primary role in regulation of respiration. If nitrite is not promptly removed, intracellular cAMP levels drop, and this impairs Crp activity. As a result, the production of nitrite reductase NrfA, CymA, and fumarate reductase FccA is substantially reduced. In contrast, nitrite can be simultaneously respired with trimethylamine N-oxide, resulting in enhanced biomass. PMID:27493647

  15. A Nitrospira metagenome illuminates the physiology and evolution of globally important nitrite-oxidizing bacteria.

    Science.gov (United States)

    Lücker, Sebastian; Wagner, Michael; Maixner, Frank; Pelletier, Eric; Koch, Hanna; Vacherie, Benoit; Rattei, Thomas; Damsté, Jaap S Sinninghe; Spieck, Eva; Le Paslier, Denis; Daims, Holger

    2010-07-27

    Nitrospira are barely studied and mostly uncultured nitrite-oxidizing bacteria, which are, according to molecular data, among the most diverse and widespread nitrifiers in natural ecosystems and biological wastewater treatment. Here, environmental genomics was used to reconstruct the complete genome of "Candidatus Nitrospira defluvii" from an activated sludge enrichment culture. On the basis of this first-deciphered Nitrospira genome and of experimental data, we show that Ca. N. defluvii differs dramatically from other known nitrite oxidizers in the key enzyme nitrite oxidoreductase (NXR), in the composition of the respiratory chain, and in the pathway used for autotrophic carbon fixation, suggesting multiple independent evolution of chemolithoautotrophic nitrite oxidation. Adaptations of Ca. N. defluvii to substrate-limited conditions include an unusual periplasmic NXR, which is constitutively expressed, and pathways for the transport, oxidation, and assimilation of simple organic compounds that allow a mixotrophic lifestyle. The reverse tricarboxylic acid cycle as the pathway for CO2 fixation and the lack of most classical defense mechanisms against oxidative stress suggest that Nitrospira evolved from microaerophilic or even anaerobic ancestors. Unexpectedly, comparative genomic analyses indicate functionally significant lateral gene-transfer events between the genus Nitrospira and anaerobic ammonium-oxidizing planctomycetes, which share highly similar forms of NXR and other proteins reflecting that two key processes of the nitrogen cycle are evolutionarily connected. PMID:20624973

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

    OpenAIRE

    Matuszak Zenon; Chignell Collin F.; Reszka Krzysztof J.

    2015-01-01

    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

  17. Positive role of nitrite as electron acceptor on anoxic denitrifying phosphorus removal process

    Institute of Scientific and Technical Information of China (English)

    HUANG RongXin; LI Dong; LI XiangKun; BAO LinLin; JIANG AnXi; ZHANG Jie

    2007-01-01

    Literatures revealed that the electron acceptor-nitrite could be inhibitory or toxic in the denitrifying phosphorus removal process.Batch test experiments were used to investigate the inhibitory effect during the anoxic condition.The inoculated activated sludge was taken from a continuous double- sludge denitrifying phosphorus and nitrogen removal system.Nitrite was added at the anoxic stage.One time injection and sequencing batch injection were carried on in the denitrifying dephosphorus procedure.The results indicated that the nitrite concentration higher than 30 mg/L would inhibit the anoxic phosphate uptake severely, and the threshold inhibitory concentration was dependent on the characteristics of the activated sludge and the operating conditions; instead, lower than the inhibitory concentration would not be detrimental to anoxic phosphorus uptake, and it could act as good electron acceptor for the anoxic phosphate accumulated.Positive effects performed during the denitrifying biological dephosphorus all the time.The utility of nitrite as good electron acceptor would provide a new feasible way in the denitrifying phosphorus process.

  18. 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.

  19. Nitrite intensity explains N management effects on N2O emissions in maize

    Science.gov (United States)

    It is typically assumed that the dependence of nitrous oxide (N2O) emissions on soil nitrogen (N) availability is best quantified in terms of ammonium (NH4+) and/or nitrate (NO3-) concentrations. In contrast, nitrite (NO2-) is seldom measured separately from NO3- despite its role as a central substr...

  20. 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- and...

  1. Nitrite-Driven Nitrous Oxide Production Under Aerobic Soil Conditions: Kinetics and Biochemical Controls

    Science.gov (United States)

    Nitrite (NO2-) can accumulate during nitrification in soil following fertilizer application. While the role of NO2- as a substrate regulating nitrous oxide (N2O) production is recognized, kinetic data are not available that allow for estimating N2O production or soil-to-atmosphere fluxes as a functi...

  2. Microbial activity catalyzes oxygen transfer in membrane-aerated nitritating biofilm reactors

    DEFF Research Database (Denmark)

    Pellicer i Nàcher, Carles; Domingo Felez, Carlos; Lackner, Susanne;

    2013-01-01

    attain partial nitritation showed that predicted oxygen transfer rates are enhanced up to six times with biofilm activity. The higher availability of ammonia at the biofilm base drives this process. Such behavior can be captured with the addition of two terms (depending on system characteristics and...

  3. Ammonia, nitrite and nitrate nitrogen removal from polluted source water with ozonation and BAC processes

    International Nuclear Information System (INIS)

    Studies on the removal of ammonia-, nitrite-, and nitrate nitrogen with ozonation (O3), sand filtration (SF), biological activated carbon (BAC), SF-BAC, and/or O3-BAC processes were carried out in two pilot plants and a full scale plant, respectively. The results showed that all of the tested processes exhibited certain nitrogen removal efficiencies, of which both the O3-SF-BAC and O3-BAC processes were most effective and efficient in removing ammonia nitrogen, with mean removal efficiencies of some 90 and 80 percent, respectively. Ozonation was found able to oxidize some organic nitrogen into ammonia, and nitrite ion into nitrate ion. It was also found out, with interest, that the O3-BAC process can carry the nitrification process to the end under sufficient DO content, as well as more hydrocarbon substrates through ozonation that are more easily assimilated by some strains of nitrobacter that can multiply heterotrophically in its carbon beds. In the BAC process, both the DO and easily assimilated substrate contents were too low in its carbon beds due to no ozonation to sustain nitrobacter growth; but the nitrite conversion bacteria, like nitrosomas, can survive under such conditions. As a result, nitrite or nitrate ion content increased multiply in the effluents from BAC or O3-BAC processes over their influents, respectively. The removal mechanisms of various processes for the three forms of nitrogen were studied and discussed, and the optimum design parameters were determined as well

  4. CONCENTRATION OF NITRATE AND NITRITE IN SOME SELECTED CEREALS SOURCED WITHIN KADUNA STATE, NIGERIA

    Directory of Open Access Journals (Sweden)

    S. ABDULRAZAK

    2014-05-01

    Full Text Available Concentrations of nitrate and nitrite ions were assessed in maize, millet, guinea corn and wheat obtained in Kaduna State, Nigeria. The results showed that nitrate ion concentration for white maize, red maize, agric millet, normal millet, white guinea corn, red guinea corn, and wheat were 4.5 mg/g, 4.2 mg/g, 15.5 mg/g, 21.3 mg/g, 6.3 mg/g, 4.0 mg/g, and 3.0 mg/g respectively. While the nitrite ion concentration for white maize, red maize, agric millet, normal millet, white guinea corn, red guinea corn, and wheat were 0.035mg/g, 0.030mg/g, 0.074 mg/g, 0.087 mg/g, 0.050 mg/g, 0.050 mg/g and 0.0154 mg/g respectively. The results obtained fall below the WHO’s Acceptable Daily Intake (ADI which is 40-100 mg/g for nitrates, and fall within range for nitrites which is 0.03 to 2.6 mg/g. This means that the nitrate and nitrite contents of maize, guinea corn, millet and wheat grown in Kaduna State may not presently pose a health hazard in the human population.

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

    International Nuclear Information System (INIS)

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

  6. 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 tem

  7. 21 CFR 573.240 - Calcium periodate.

    Science.gov (United States)

    2010-04-01

    ... with calcium hydroxide or calcium oxide to form a substance consisting of not less than 60 percent by... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium periodate. 573.240 Section 573.240 Food... Additive Listing § 573.240 Calcium periodate. The food additive calcium periodate may be safely used...

  8. 21 CFR 573.260 - Calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium silicate. 573.260 Section 573.260 Food and... Listing § 573.260 Calcium silicate. Calcium silicate, including synthetic calcium silicate, may be safely used as an anticaking agent in animal feed, provided that the amount of calcium silicate does...

  9. Calcium measurement methods

    Directory of Open Access Journals (Sweden)

    CarloAlberto Redi

    2010-09-01

    Full Text Available Rightly stressed by prof. Wolfgang Walz in the Preface to the series Neuromethods series, the “careful application of methods is probably the most important step in the process of scientific inquiry”. Thus, I strongly suggest to all those interested in calcium signaling and especially to the new-comers in the hot topic of neuroscience (which has so much space even in science-society debate for its implications in legal issues and in the judge-decision process to take profit from this so well edited book. I am saying this since prof. Verkhratsky and prof. Petersen......

  10. Tolerance of ciliated protozoan Paramecium bursaria (Protozoa, Ciliophora) to ammonia and nitrites

    Science.gov (United States)

    Xu, Henglong; Song, Weibo; Lu, Lu; Alan, Warren

    2005-09-01

    The tolerance to ammonia and nitrites in freshwater ciliate Paramecium bursaria was measured in a conventional open system. The ciliate was exposed to different concentrations of ammonia and nitrites for 2h and 12h in order to determine the lethal concentrations. Linear regression analysis revealed that the 2h-LC50 value for ammonia was 95.94 mg/L and for nitrite 27.35 mg/L using probit scale method (with 95% confidence intervals). There was a linear correlation between the mortality probit scale and logarithmic concentration of ammonia which fit by a regression equation y=7.32 x 9.51 ( R 2=0.98; y, mortality probit scale; x, logarithmic concentration of ammonia), by which 2 h-LC50 value for ammonia was found to be 95.50 mg/L. A linear correlation between mortality probit scales and logarithmic concentration of nitrite is also followed the regression equation y=2.86 x+0.89 ( R 2=0.95; y, mortality probit scale; x, logarithmic concentration of nitrite). The regression analysis of toxicity curves showed that the linear correlation between exposed time of ammonia-N LC50 value and ammonia-N LC50 value followed the regression equation y=2 862.85 e -0.08 x ( R 2=0.95; y, duration of exposure to LC50 value; x, LC50 value), and that between exposed time of nitrite-N LC50 value and nitrite-N LC50 value followed the regression equation y=127.15 e -0.13 x ( R 2=0.91; y, exposed time of LC50 value; x, LC50 value). The results demonstrate that the tolerance to ammonia in P. bursaria is considerably higher than that of the larvae or juveniles of some metozoa, e.g. cultured prawns and oysters. In addition, ciliates, as bacterial predators, are likely to play a positive role in maintaining and improving water quality in aquatic environments with high-level ammonium, such as sewage treatment systems.

  11. Control of sulfide and methane production in anaerobic sewer systems by means of Downstream Nitrite Dosage.

    Science.gov (United States)

    Auguet, Olga; Pijuan, Maite; Borrego, Carles M; Gutierrez, Oriol

    2016-04-15

    Bioproduction of hydrogen sulfide (H2S) and methane (CH4) under anaerobic conditions in sewer pipes causes detrimental effects on both sewer facilities and surrounding environment. Among the strategies used to mitigate the production of both compounds, the addition of nitrite (NO2(-)) has shown a greater long-term inhibitory effect compared with other oxidants such as nitrate or oxygen. The aim of this study was to determine the effectiveness of a new method, the Downstream Nitrite Dosage strategy (DNO2D), to control H2S and CH4 emissions in sewers. Treatment effectiveness was assessed on H2S and CH4 abatement on the effluent of a laboratory sewer pilot plant that mimics a full-scale anaerobic rising sewer. The experiment was divided in three different periods: system setup (period 1), nitrite addition (period 2) and system recovery (period 3). Different process and molecular methods were combined to investigate the impact of NO2(-) addition on H2S and CH4 production. Results showed that H2S load was reduced completely during nitrite addition when compared to period 1 due to H2S oxidation but increased immediately after nitrite addition stopped. The H2S overproduction during recovery period was associated with the bacterial reduction of different sulfur species (elemental sulfur/thiosulfate/sulfite) accumulated within the sewer biofilm matrix. Oxidation of CH4 was also detected during period 2 but, contrary to sulfide production, re-establishment of methanogenesis was not immediate after stopping nitrite dosing. The analysis of bulk and active microbial communities along experimental treatment showed compositional changes that agreed with the observed dynamics of chemical processes. Results of this study show that DNO2D strategy could significantly reduce H2S and CH4 emissions from sewers during the addition period but also suggest that microbial agents involved in such processes show a high resilience towards chemical stressors, thus favoring the re

  12. Tolerance of ciliated protozoan Paramecium bursaria (Protozoa,Ciliophora) to ammonia and nitrites

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The tolerance to ammonia and nitrites in freshwater ciliate Paramecium bursaria was measured in a conventional open system. The ciliate was exposed to different concentrations of ammonia and nitrites for 2h and 12h in order to determine the lethal concentrations. Linear regression analysis revealed that the 2h-LC50 value for ammonia was 95.94 mg/L and for nitrite 27.35 mg/L using probit scale method (with 95% confidence intervals). There was a linear correlation between the mortality probit scale and logarithmic concentration of ammonia which fit by a regression equation y=7.32x-9.51 (R2=0.98; y, mortality probit scale; x, logarithmic concentration of ammonia), by which 2 h-LC50 value for ammonia was fotnd to be 95.50 mg/L. A linear correlation between mortality probit scales and logarithmic concentration of nitrite is also followed the regression equation y=2.86x+0.89 (R2=0.95; y, mortality probit scale; x, logarithmic concentration of nitrite). The regression analysis of toxicity curves showed that the linear correlation between exposed time of ammonia-N LC50 value and ammonia-N LC50 value followed the regression equation y=2862.85e-0.0ax (R2=0.95; y, duration of exposure to LC50 value; x, LC50 value), and that between exposed time of nitrite-N LC50 value and nitrite-N LC50 value followed the regression equation y = 127.15e-0.13x (R2=0.91; y, exposed time of LC50 value; x, LC50 value). The results demonstrate that the tolerance to ammonia in P. bursaria is considerably higher than that of the larvae or juveniles of some metozoa, e.g. cultured prawns and oysters. In addition, ciliates, as bacterial predators, are likely to play a positive role in maintaining and improving water quality in aquatic environments with high-level ammonium, such as sewage treatment systems.

  13. Using Salivary Nitrite and Nitrate Levels as a Biomarker for Drug-Induced Gingival Overgrowth

    Science.gov (United States)

    Sukuroglu, Erkan; Güncü, Güliz N.; Kilinc, Kamer; Caglayan, Feriha

    2015-01-01

    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. Materials 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 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 nitrate levels (p 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 phenytoin induced gingival overgrowth, and that saliva seems to have a better diagnostic potential than GCF

  14. Extracellular calcium sensing and extracellular calcium signaling

    Science.gov (United States)

    Brown, E. M.; MacLeod, R. J.; O'Malley, B. W. (Principal Investigator)

    2001-01-01

    , localized changes in Ca(o)(2+) within the ECF can originate from several mechanisms, including fluxes of calcium ions into or out of cellular or extracellular stores or across epithelium that absorb or secrete Ca(2+). In any event, the CaR and other receptors/sensors for Ca(o)(2+) and probably for other extracellular ions represent versatile regulators of numerous cellular functions and may serve as important therapeutic targets.

  15. 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.

  16. Average daily nitrate and nitrite intake in the Belgian population older than 15 years.

    Science.gov (United States)

    Temme, E H M; Vandevijvere, S; Vinkx, C; Huybrechts, I; Goeyens, L; Van Oyen, H

    2011-09-01

    The aim of this study was to assess the dietary intake of nitrate and nitrite in Belgium. The nitrate content of processed vegetables, cheeses and meat products was analysed. These data were completed by data from non-targeted official control and from the literature. In addition, the nitrite content of meat products was measured. Concentration data for nitrate and nitrite were linked to food consumption data of the Belgian Food Consumption Survey. This study included 3245 respondents, aged 15 years and older. Food intakes were estimated by a repeated 24-h recall using EPIC-SOFT. Only respondents with two completed 24-h recalls (n=3083) were included in the analysis. For the intake assessment, average concentration data and individual consumption data were combined. Usual intake of nitrate/nitrite was calculated using the Nusser method. The mean usual daily intake of nitrate was 1.38 mg kg(-1) bodyweight (bw) day(-1) and the usual daily intake at the 97.5 percentile was 2.76 mg kg(-1) bw day(-1). Exposure of the Belgian population to nitrate at a mean intake corresponded to 38% of the ADI (while 76% at the 97.5 percentile). For the average consumer, half of the intake was derived from vegetables (especially lettuce) and 20% from water and water-based drinks. The average daily intake of nitrate and nitrite from cheese and meat products was low (0.2% and 6% of the ADI at average intake, respectively). Scenario analyses with a higher consumption of vegetables or a higher nitrate concentration in tap water showed a significant higher intake of nitrate. Whether this is beneficial or harmful must be further assessed. PMID:21728895

  17. PENURUNAN KADAR AMONIA, NITRIT, DAN NITRAT LIMBAH CAIR INDUSTRI TAHU MENGGUNAKAN ARANG AKTIF DARI AMPAS KOPI

    Directory of Open Access Journals (Sweden)

    Irmanto

    2009-11-01

    Full Text Available The tofu industry is one of food industry which the product of organic waste to environment pollution. One of alternative methode which used to overcome tofu industrial waste water pollution is adsorption methode using activated carbon from coffee waste. The aim of this researched is to know about the activated carbon from coffee waste quality which observe of rendemen, water content, ash content, and iodium adsorption, to know optimum contact of time and pH of coffee waste to decrease ammonia, nitrite and nitrate contents in tofu industry waste water and to know decrease percentage of ammonia, nitrite and nitrate contents in tofu industrial waste water using activated carbon from coffee waste. The activated carbon made by soaking of coffee waste in HCl 0.1 M solution for 2 days. The activated carbon coaled in muffle furnace at temperature 350°C. The activated carbon analyzed consist of rendemen, water content, ash content, and iodium adsorption. Optimum contact of time and pH of coffee waste determined in order to get optimum adsorption ammonia, nitrite and nitrate in tofu industrial waste water. Contact time variation are 1, 10, 30, 45, 60, 90, 120 minutes and pH variation are 4, 5, 6, 7, 8, 9, 10. The result showed that the activated carbon from coffee waste fulfill the criteria SNI number 06-3730-1995. The activated carbon from coffee waste could be used to decrease the ammonia, nitrite, and nitrate contents in tofu industrial waste water at the optimum contact of time of 30 minutes and pH 7. Decreasing percentage of ammonia, nitrite and nitrate contents in tofu industrial waste water are 64,69% , 52,35% and 86,40% respectively.

  18. Stable Copper-Nitrosyl Formation By Nitrite Reductase in Either Oxidation State

    Energy Technology Data Exchange (ETDEWEB)

    Tocheva, E.I.; Rosell, F.I.; Mauk, A.G.; Murphy, M.E.P.

    2009-06-04

    Nitrite reductase (NiR) is an enzyme that uses type 1 and type 2 copper sites to reduce nitrite to nitric oxide during bacterial denitrification. A copper-nitrosyl intermediate is a proposed, yet poorly characterized feature of the NiR catalytic cycle. This intermediate is formally described as Cu(I)-NO{sup +} and is proposed to be formed at the type 2 copper site after nitrite binding and electron transfer from the type 1 copper site. In this study, copper-nitrosyl complexes were formed by prolonged exposure of exogenous NO to crystals of wild-type and two variant forms of NiR from Alcaligenes faecalis (AfNiR), and the structures were determined to 1.8 {angstrom} or better resolution. Exposing oxidized wild-type crystals to NO results in the reverse reaction and formation of nitrite that remains bound at the active site. In a type 1 copper site mutant (H145A) that is incapable of electron transfer to the type 2 site, the reverse reaction is not observed. Instead, in both oxidized and reduced H145A crystals, NO is observed bound in a side-on manner to the type 2 copper. In AfNiR, Asp98 forms hydrogen bonds to both substrate and product bound to the type 2 Cu. In the D98N variant, NO is bound side-on but is more disordered when observed for the wild-type enzyme. The solution EPR spectra of the crystallographically characterized NiR-NO complexes indicate the presence of an oxidized type 2 copper site and thus are interpreted as resulting from stable copper-nitrosyls and formally assigned as Cu(II)-NO{sup -}. A reaction scheme in which a second NO molecule is oxidized to nitrite can account for the formation of a CuD-NO{sup -} species after exposure of the oxidized H145A variant to NO gas.

  19. Linkage isomerization in heme-NOx compounds: understanding NO, nitrite, and hyponitrite interactions with iron porphyrins.

    Science.gov (United States)

    Xu, Nan; Yi, Jun; Richter-Addo, George B

    2010-07-19

    Nitric oxide (NO) and its derivatives such as nitrite and hyponitrite are biologically important species of relevance to human health. Much of their physiological relevance stems from their interactions with the iron centers in heme proteins. The chemical reactivities displayed by the heme-NOx species (NOx = NO, nitrite, hyponitrite) are a function of the binding modes of the NOx ligands. Hence, an understanding of the types of binding modes extant in heme-NOx compounds is important if we are to unravel the inherent chemical properties of these NOx metabolites. In this Forum Article, the experimentally characterized linkage isomers of heme-NOx models and proteins are presented and reviewed. Nitrosyl linkage isomers of synthetic iron and ruthenium porphyrins have been generated by photolysis at low temperatures and characterized by spectroscopy and density functional theory calculations. Nitrite linkage isomers in synthetic metalloporphyrin derivatives have been generated from photolysis experiments and in low-temperature matrices. In the case of nitrite adducts of heme proteins, both N and O binding have been determined crystallographically, and the role of the distal H-bonding residue in myoglobin in directing the O-binding mode of nitrite has been explored using mutagenesis. To date, only one synthetic metalloporphyrin complex containing a hyponitrite ligand (displaying an O-binding mode) has been characterized by crystallography. This is contrasted with other hyponitrite binding modes experimentally determined for coordination compounds and computationally for NO reductase enzymes. Although linkage isomerism in heme-NOx derivatives is still in its infancy, opportunities now exist for a detailed exploration of the existence and stabilities of the metastable states in both heme models and heme proteins. PMID:20666385

  20. 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.

  1. 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

  2. Respiratory detoxification of nitric oxide by the cytochrome c nitrite reductase of Escherichia coli.

    Science.gov (United States)

    Poock, Susannah R; Leach, Emily R; Moir, James W B; Cole, Jeffrey A; Richardson, David J

    2002-06-28

    Nitric oxide is a key element in host defense against invasive pathogens. The periplasmic cytochrome c nitrite reductase (NrfA) of Escherichia coli catalyzes the respiratory reduction of nitrite, but in vitro studies have shown that it can also reduce nitric oxide. The physiological significance of the latter reaction in vivo has never been assessed. In this study the reduction of nitric oxide by Escherichia coli was measured in strains active or deficient in periplasmic nitrite reduction. Nrf(+) cells, harvested from cultures grown anaerobically, possessed a nitric-oxide reductase activity with physiological electron donation of 60 nmol min(-1) x mg dry wt(-1), and an in vivo turnover number of NrfA of 390 NO* s(-1) was calculated. Nitric-oxide reductase activity could not be detected in Nrf(-) strains. Comparison of the anaerobic growth of Nrf(+) and Nrf(-) strains revealed a higher sensitivity to nitric oxide in the NrfA(-) strains. A higher sensitivity to the nitrosating agent S-nitroso-N-acetyl penicillamine (SNAP) was also observed in agar plate disk-diffusion assays. Oxygen respiration by E. coli was also more sensitive to nitric oxide in the Nrf(-) strains compared with the Nrf(+) parent strain. The results demonstrate that active periplasmic cytochrome c nitrite reductase can confer the capacity for nitric oxide reduction and detoxification on E. coli. Genomic analysis of many pathogenic enteric bacteria reveals the presence of nrf genes. The present study raises the possibility that this reflects an important role for the cytochrome c nitrite reductase in nitric oxide management in oxygen-limited environments. PMID:11960983

  3. Levels of nitrates and nitrites in chili pepper and ventricina salami

    Directory of Open Access Journals (Sweden)

    Giampaolo Colavita

    2014-06-01

    Full Text Available Ventricina is a traditional sausage made from pork meat produced in the Abruzzi and Molise regions. The aim of this study was to detect the content of nitrates and nitrites in local cultivars of chilli pepper, and their concentration in ventricina samples spiced with the same chilli pepper. Furthermore, it was examined whether, in the samples of ventricina with nitrate addition, the spicing with chilli pepper could exceed the maximum added dose. The concentration of nitrates and nitrites in the organic chilli pepper was 531.0±94.6 mg/kg and less than 5.0 mg, respectively, in the traditional chilli pepper it was 394.0±39.6 and less than 5.0 mg, while in the commercial it was 325.0±115.0 and less than 5.0 mg. The determination of nitrites and nitrates was carried out by high performance ion chromatography. In ventricina samples produced without added sodium nitrate, nitrates and nitrites were below 5.0 mg/kg at the case-filling time (t0 and after 50 days of aging (t50. In the samples of ventricina with added sodium nitrate, nitrate concentration values were 134.0±20.9 mg/kg at t0 and 129.0±15.4 mg/kg at t50, while the nitrites were below 5.0 mg/kg at t0 and 28.8±15.8 mg/kg at t50. Although in ventricina the amount of chilli pepper is quite relevant, it did not lead to a detectable concentration of nitrates. The maximum allowed amount was never exceeded.

  4. A novel marine nitrite-oxidizing Nitrospira species from Dutch coastal North Sea water

    Directory of Open Access Journals (Sweden)

    Suzanne Caroline Marianne Haaijer

    2013-03-01

    Full Text Available Marine microorganisms are important for the global nitrogen cycle, but marine nitrifiers, especially aerobic nitrite-oxidizers, remain largely unexplored. To increase the number of cultured representatives of marine nitrite-oxidizing bacteria (NOB, a bioreactor cultivation approach was adopted to first enrich nitrifiers and ultimately nitrite oxidizers from Dutch coastal North Sea water. With solely ammonia as the substrate an active nitrifiying community consisting of novel marine Nitrosomonas aerobic ammonia oxidizers (AOB and Nitrospina and Nitrospira NOB was obtained which converted a maximum of 2 mmoles of ammonia per liter per day. Switching the feed of the culture to nitrite as a sole substrate resulted in a Nitrospira NOB dominated community (approximately 80% of the total microbial community based on FISH and metagenomic data converting a maximum of 3 mmoles of nitrite per liter per day. Phylogenetic analyses based on the 16S rRNA gene indicated that the Nitrospira enriched from the North Sea is a novel Nitrospira species with Nitrospira marina as the next taxonomically described relative (94% 16S rRNA sequence identity. Transmission electron microscopy analysis revealed a cell plan typical for Nitrospira species. The cytoplasm contained electron light particles that might represent glycogen storage. A large periplasmic space was present which was filled with electron dense particles. Nitrospira-targeted PCR analyses demonstrated the presence of the enriched Nitrospira species in a time series of North Sea genomic DNA samples. The availability of this new Nitrospira species enrichment culture facilitates further in-depth studies such as determination of physiological constraints, and comparison to other NOB species.

  5. Dietary Nitrates, Nitrites, and Nitrosamines Intake and the Risk of Gastric Cancer: A Meta-Analysis.

    Science.gov (United States)

    Song, Peng; Wu, Lei; Guan, Wenxian

    2015-12-01

    The potential associations between dietary consumption of nitrates, nitrites, and nitrosamines and gastric cancer risk have been investigated by several studies, but yielded inconclusive results. We conducted a meta-analysis to provide a quantitative assessment of their relationships. Relevant articles were identified by a systematic literature searching of PubMed and Embase databases prior to August 2015. Random-effects models were employed to pool the relative risks. A total of 22 articles consisting of 49 studies-19 studies for nitrates, 19 studies for nitrites, and 11 studies for N-nitrosodimethylamine (NDMA)-were included. The summary relative risk of stomach cancer for the highest categories, compared with the lowest, was 0.80 (95% confidence interval (CI), 0.69-0.93) for dietary nitrates intake, 1.31 (95% CI, 1.13-1.52) for nitrites, and 1.34 (95% CI, 1.02-1.76) for NDMA (p for heterogeneity was 0.015, 0.013 and nitrates and nitrites. The heterogeneity for NDMA could not be eliminated completely through stratified analysis. Although significant associations were all observed in case-control studies, the cohort studies still showed a slight trend. The dose-response analysis indicated similar results as well. High nitrates intake was associated with a weak but statistically significant reduced risk of gastric cancer. Whereas increased consumption of nitrites and NDMA seemed to be risk factors for cancer. Due to the lack of uniformity for exposure assessment across studies, further prospective researches are warranted to verify these findings. PMID:26633477

  6. Dietary Nitrates, Nitrites, and Nitrosamines Intake and the Risk of Gastric Cancer: A Meta-Analysis

    Directory of Open Access Journals (Sweden)

    Peng Song

    2015-12-01

    Full Text Available The potential associations between dietary consumption of nitrates, nitrites, and nitrosamines and gastric cancer risk have been investigated by several studies, but yielded inconclusive results. We conducted a meta-analysis to provide a quantitative assessment of their relationships. Relevant articles were identified by a systematic literature searching of PubMed and Embase databases prior to August 2015. Random-effects models were employed to pool the relative risks. A total of 22 articles consisting of 49 studies—19 studies for nitrates, 19 studies for nitrites, and 11 studies for N-nitrosodimethylamine (NDMA—were included. The summary relative risk of stomach cancer for the highest categories, compared with the lowest, was 0.80 (95% confidence interval (CI, 0.69–0.93 for dietary nitrates intake, 1.31 (95% CI, 1.13–1.52 for nitrites, and 1.34 (95% CI, 1.02–1.76 for NDMA (p for heterogeneity was 0.015, 0.013 and <0.001, respectively. The study type was found as the main source of heterogeneity for nitrates and nitrites. The heterogeneity for NDMA could not be eliminated completely through stratified analysis. Although significant associations were all observed in case-control studies, the cohort studies still showed a slight trend. The dose-response analysis indicated similar results as well. High nitrates intake was associated with a weak but statistically significant reduced risk of gastric cancer. Whereas increased consumption of nitrites and NDMA seemed to be risk factors for cancer. Due to the lack of uniformity for exposure assessment across studies, further prospective researches are warranted to verify these findings.

  7. Compartmentalization of the submembrane calcium activity during calcium influx and its significance in transmitter release.

    OpenAIRE

    Simon, S M; Llinás, R R

    1985-01-01

    Quantitative modeling indicates that, in presynaptic terminals, the intracellular calcium concentration profile during inward calcium current is characterized by discrete peaks of calcium immediately adjacent to the calcium channels. This restriction of intracellular calcium concentration suggests a remarkably well specified intracellular architecture such that calcium, as a second messenger, may regulate particular intracellular domains with a great degree of specificity.

  8. 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. PMID:26159506

  9. Thymoquinone ameliorated elevated inflammatory cytokines in testicular tissue and sex hormones imbalance induced by oral chronic toxicity with sodium nitrite.

    Science.gov (United States)

    Alyoussef, Abdullah; Al-Gayyar, Mohammed M H

    2016-07-01

    Scientific evidence illustrated the health hazards of exposure to nitrites for prolonged time. Nitrites affected several body organs due to oxidative, inflammatory and apoptosis properties. Furthermore, thymoquinone (TQ) had curative effects against many diseases. We tried to discover the impact of both sodium nitrite and TQ on inflammatory cytokines contents in testicular tissues and hormonal balance both in vivo and in vitro. Fifty adult male SD rats received 80mg/kg sodium nitrite and treated with either 25 or 50mg/kg TQ daily by oral-gavage for twelve weeks. Testis were removed for sperms' count. Testicular tissue homogenates were used for assessment of protein and gene expression of IL-1β, IL-6, TNF-α, Nrf2 and caspase-3. Serum samples were used for measurement of testosterone, LH, FSH and prolactin. Moreover, all the parameters were measured in human normal testis cell-lines, CRL-7002. Sodium nitrite produced significant decrease in serum testosterone associated with raised FSH, LH and prolactin. Moreover, sodium nitrite significantly elevated TNF-α, IL-1β, IL-6, caspase-3 and reduced Nrf2. TQ significantly reversed all these effects both in vivo and in vitro. In conclusion, TQ ameliorated testicular tissue inflammation and restored the normal balance of sex hormones induced by sodium nitrite both in vivo and in vitro. PMID:27038016

  10. Vitamin D, Calcium, and Bone Health

    Science.gov (United States)

    ... Balance › Vitamin D, Calcium, and Bone Health Vitamin D, Calcium, and Bone Health March 2012 Download PDFs ... helps keep your bones strong. Why are vitamin D and calcium important to bone health? Vitamin D ...

  11. 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 ...

  12. Calcium transport in turtle bladder

    International Nuclear Information System (INIS)

    Unidirectional 45Ca fluxes were measured in the turtle bladder under open-circuit and short-circuit conditions. In the open-circuited state net calcium flux (JnetCa) was secretory (serosa to mucosa). Ouabain reversed JnetCa to an absorptive flux. Amiloride reduced both fluxes such that JnetCa was not significantly different from zero. Removal of mucosal sodium caused net calcium absorption; removal of serosal sodium caused calcium secretion. When bladders were short circuited, JnetCa decreased to approximately one-third of control value but remained secretory. When ouabain was added under short-circuit conditions, JnetCa was similar in magnitude and direction to ouabain under open-circuited conditions (i.e., absorptive). Tissue 45Ca content was ≅30-fold lower when the isotope was placed in the mucosal bath, suggesting that the apical membrane is the resistance barrier to calcium transport. The results obtained in this study are best explained by postulating a Ca2+-ATPase on the serosa of the turtle bladder epithelium and a sodium-calcium antiporter on the mucosa. In this model, the energy for calcium movement would be supplied, in large part, by the Na+-K+-ATPase. By increasing cell sodium, ouabain would decrease the activity of the mucosal sodium-calcium exchanger (or reverse it), uncovering active calcium transport across the serosa

  13. An Improved Calcium Flame Test.

    Science.gov (United States)

    Pearson, Robert S.

    1985-01-01

    Indicates that the true red color of calcium can be obtained (using the procedure described by Sorm and Logowski) if the calcium ion solution is mixed with an equal volume of saturated ammonium bromide solution. Suggestions for flame tests of other elements are also noted. (JN)

  14. A new, fast and sensitive method for the determination of trace amounts of nitrite using differential pulse polarography.

    Science.gov (United States)

    Somer, Güler; Kalaycı, Şükrü; Almas, Ziya

    2016-07-01

    Nitrite salts of sodium or potassium are being used for the protection of meat products. They provide color and taste of meat and they protect against clostridia. On the other hand, nitrite ions can interact with amines to form nitrosamines which are known as carcinogenic substances. They may also react with hemoglobin and reduce its oxygen carrying capacity. Thus, its concentration in food-stuff has to be controlled carefully by highly sensitive methods. A new DP polarographic method is established for the determination of nitrite. Nitrite cannot be determined directly with any analytical methods. Long and tedious procedures are necessary for many of them. In this polarographic method arsenite, As(III), ion is used for the reduction of nitrite. The nitrite is determined from the As(III) quantity left over after the reaction with nitrite. The peak of arsenite has been used since it is sharp and responds well for the standard addition of arsenite. The optimum conditions for the quantitative reaction between nitrite and arsenite have been studied. It was found that the pH for the reaction medium has to be 5-7, since nitrite is decomposed at lower pH values. The reaction medium has to be stirred for about 5 min with nitrogen gas in order to expel the NO gas formed and thus to shift the equilibrium to products side. The limit of detection, LOD, was found to be as 2 × 10(-7) M. No interference was observed from most common ions. PMID:27153987

  15. CALCIUM ENHANCES ANTIINFLAMMATORY ACTIVITY OF ASPIRIN

    OpenAIRE

    Choksi Krishna; Shenoy Ashoka M; A. R. Shabharaya; Lala Minaxi

    2011-01-01

    The objective of present study is to evaluate the effects of calcium carbonate and calcium gluconate on acute and subacute inflammation and to study their possible interactions with Aspirin. Calcium carbonate (10 mg/kg) and calcium gluconate (5 mg/kg) were administered individually and also co-administered along with sub therapeutic dose Aspirin (50mg/kg) to study their interaction. The inflammation was induced by carrageenan or a foreign body. Both calcium carbonate and calcium gluconate cou...

  16. 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

    anoxia-tolerance of this fish by measuring NO metabolites in normoxic, anoxic and reoxygenated crucian carp. We also cloned and sequenced crucian carp NO synthase variants and quantified their mRNA levels in several tissues in normoxia and anoxia. Despite falling levels of blood plasma nitrite, the....... We conclude that nitrite is shifted into the tissues where it acts as NO donor during anoxia, inducing cytoprotection under anoxia/reoxygenation. This can be especially important in the crucian carp heart, which maintains output in anoxia. Nitrite is currently tested as a therapeutic drug against...

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

    OpenAIRE

    W.J. Wiese; J.P.J. Joubert

    2001-01-01

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

  18. Penetapan Kadar Nitrit Dan Nitrat Di Dalam Sosis Yang Beredar Di Kota Medan Secara Spektrofotometri Sinar Tampak

    OpenAIRE

    Lusiana, Rosalinda

    2016-01-01

    Nitrites and nitrates are foot additives that can be used as a preservative. According to the requirement of the Minister of Health of Indonesia RI number 722/MENKES/IX/1988, level allowed for nitrites in processed meat is 125 μg/g, wheres for nitrates is 500 μg/g. The purpose of this study was to determine the amount of nitrites and nitrates found in sausages marketed the supermarket in Medan. The samples analyzed were five sausages products are branded and unbranded two sausages products...

  19. Cooperative use of cytochrome cd{sub 1} nitrite reductase and its redox partner cytochrome c{sub 552} to improve the selectivity of nitrite biosensing

    Energy Technology Data Exchange (ETDEWEB)

    Serra, A.S.; Jorge, S.R.; Silveira, C.M.; Moura, J.J.G. [REQUIMTE - Dept. de Quimica, CQFB, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Jubete, E.; Ochoteco, E.; Cabanero, G.; Grande, H. [CIDETEC - Centro de Tecnologias Electroquimicas, Parque Tecnologico de San Sebastian, Po Miramon, 196, 20009 Donostia - San Sebastian (Spain); Almeida, M.G., E-mail: mga@dq.fct.unl.pt [REQUIMTE - Dept. de Quimica, CQFB, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Escola Superior de Saude Egas Moniz, Monte de Caparica, 2829-511 Caparica (Portugal)

    2011-05-05

    In this work, a novel enzymatic biosensor for determination of nitrites constructed on an electrochemical transducing platform is proposed. The sensor is based on cytochrome-cd{sub 1} (cyt-cd{sub 1}) nitrite reductase from Marinobacter hydrocarbonoclasticus strain 617 as biological recognition element, and its putative physiological redox partner cytochrome-c{sub 552} (cyt-c{sub 552}), as electron mediator. The proteins were co-immobilized using a photopolymerizable polyvinyl alcohol (PVA) derivative, onto carbon paste screen printed electrodes (CPSPEs); the optimal modification conditions were 100 {mu}M cyt-cd{sub 1}/100 {mu}M cyt-c{sub 552} and 50% PVA, after a 48 h polymerization time. Electrochemical characterization of the mediator was carried out by cyclic voltammetry. The one-electron exchange between cyt-c{sub 552} and the working electrode is a quasi-reversible process, without mass transport limitations. The formal potential of the mediator is 254 {+-} 2 mV vs NHE and the intermolecular electron transfer rate constant between cytochromes c{sub 552} and cd{sub 1} is 9.9 x 10{sup 3} M{sup -1} s{sup -1}. The analytical parameters of the biosensor response to nitrite as assessed by amperometric measurements were: linear range from 10 to 200 {mu}M; detection and quantification limits of 7 and 24 {mu}M, respectively; sensitivity of 2.49 {+-} 0.08 A mol{sup -1} cm{sup 2} {mu}M{sup -1}. Catalytic profiles in the presence of possible interfering species were also investigated. The interference from competitive enzymatic reduction of dissolved oxygen could be overcome by tuning the cyclic voltammograms for faster sweep rates.

  20. 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. PMID:26699517

  1. 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.

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

    International Nuclear Information System (INIS)

    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 and monocarboaluminate. Increasing the ratio between sulfate and aluminate decreases the extent of limestone reaction

  3. Calcium binding protein-mediated regulation of voltage-gated calcium channels linked to human diseases

    Institute of Scientific and Technical Information of China (English)

    Nasrin NFJATBAKHSH; Zhong-ping FENG

    2011-01-01

    Calcium ion entry through voltage-gated calcium channels is essential for cellular signalling in a wide variety of cells and multiple physiological processes. Perturbations of voltage-gated calcium channel function can lead to pathophysiological consequences. Calcium binding proteins serve as calcium sensors and regulate the calcium channel properties via feedback mechanisms. This review highlights the current evidences of calcium binding protein-mediated channel regulation in human diseases.

  4. A nanomaterial composed of cobalt nanoparticles, poly(3,4-ethylenedioxythiophene) and graphene with high electrocatalytic activity for nitrite oxidation

    International Nuclear Information System (INIS)

    We have investigated the oxidative electrochemistry of nitrite on glassy carbon electrodes modified with cobalt nanoparticles, poly(3,4-ethylenedioxythiophene) (PEDOT), and graphene. The modified electrode was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy. The results suggest that this new type of electrode combines the advantages of PEDOT-graphene films and cobalt nanoparticles and exhibits excellent electrocatalytic activity towards the oxidation of nitrite. There is a linear relationship between the peak current and the nitrite concentration in the range from 0.5 μM to 240 μM, and the detection limit is 0.15 μM. The modified electrodes also enable the determination of nitrite at low potentials where the noise level and interferences by other electro-oxidizable compounds are weak. (author)

  5. Nitric oxide formation from the reaction of nitrite with carp and rabbit hemoglobin at intermediate oxygen saturations

    DEFF Research Database (Denmark)

    Jensen, Frank Bo

    2008-01-01

    The nitrite reductase activity of deoxyhemoglobin has received much recent interest because the nitric oxide produced in this reaction may participate in blood flow regulation during hypoxia. The present study used spectral deconvolution to characterize the reaction of nitrite with carp and rabbit...... hemoglobin at different constant oxygen tensions that generate the full range of physiological relevant oxygen saturations. Carp is a hypoxia-tolerant species with very high hemoglobin oxygen affinity, and the high R-state character and low redox potential of the hemoglobin is hypothesized to promote NO...... generation from nitrite. The reaction of nitrite with deoxyhemoglobin leads to a 1 : 1 formation of nitrosylhemoglobin and methemoglobin in both species. At intermediate oxygen saturations, the reaction with deoxyhemoglobin is clearly favored over that with oxyhemoglobin, and the oxyhemoglobin reaction and...

  6. Hollow Fe2O3 polyhedrons: One-pot synthesis and their use as electrochemical material for nitrite sensing

    International Nuclear Information System (INIS)

    In this paper, hollow hematite nano-polyhedrons (Fe-HNPs) were synthesized via a facile solution route. The abundance of high indexed facets was demonstrated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. A new electrochemical biosensor for nitrite determination was then proposed by using the hematite hollow nanopolyhedron as the sensing layer. Electrochemical tests showed that the Fe-HNPs could act as efficient enzyme-like electron mediators for nitrite oxidation. As a result, the Fe2O3 modified biosensor exhibited excellent performance for the determination of nitrite with a response time of −1. A high selectivity and long-term stability toward nitrite oxidation in the presence of glucose and L-ascorbic (AA) was also observed at their maximum physiological concentrations, which made this novel Fe2O3 nanomaterial bounded with high indexed facets promising for sensing applications in medicine, biotechnology and environmental chemistry.

  7. 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.

  8. Oxidation phenomena and color properties of grape pomace on nitrite-reduced meat emulsion systems.

    Science.gov (United States)

    Riazi, Fatemeh; Zeynali, Fariba; Hoseini, Ebrahim; Behmadi, Homa; Savadkoohi, Sobhan

    2016-11-01

    The present study focuses on the effect of different levels of red grape pomace (1 and 2%, w/w) on the color changes, lipid oxidation (TBARS), antioxidant activity, microbial counts, total phenol content and sensory attributes of the sausages formulated with various levels of sodium nitrite (30, 60 and 120mg/kg). It was found that the addition of grape pomace (1%, w/w) in combination of reduced nitrite levels to the beef sausage samples reduced TBARS content and the degree of lipid oxidation. Antioxidant activity and total phenol contents were further evaluated based on DPPH scavenging activity method. A significant reduction in lightness (L*) and yellowness (b*) of systems containing grape pomace was observed, following by an increase in the oxidative stability and the radical scavenging activity. Acceptability of beef sausages was not significantly (P>0.05) affected by the addition of grape pomace and had relatively greater scores from a sensory point of view. PMID:27424305

  9. 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 microg/ml with 3delta 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. PMID:15863058

  10. Simultaneous nitritation and p-nitrophenol removal using aerobic granular biomass in a continuous airlift reactor.

    Science.gov (United States)

    Jemaat, Zulkifly; Suárez-Ojeda, María Eugenia; Pérez, Julio; Carrera, Julián

    2013-12-01

    The chemical and petrochemical industries produce wastewaters containing ammonium and phenolic compounds. Biological treatment of these wastewaters could be problematic due to the possible inhibitory effects exerted by phenolic compounds. The feasibility of performing simultaneous nitritation and p-nitrophenol (PNP) biodegradation using a continuous aerobic granular reactor was evaluated. A nitrifying granular sludge was bioaugmented with a PNP-degrading floccular sludge, while PNP was progressively added to the feed containing a high ammonium concentration. Nitritation was sustained throughout the operational period with ca. 85% of ammonium oxidation and less than 0.3% of nitrate in the effluent. PNP biodegradation was unstable and the oxygen limiting condition was found to be the main explanation for this unsteadiness. An increase in dissolved oxygen concentration from 2.0 to 4.5 mg O2 L(-1) significantly enhanced PNP removal, achieving total elimination. Acinetobacter genus and ammonia-oxidising bacteria were the predominant bacteria species in the granular biomass. PMID:24177164

  11. Hierarchical CuO nanochains: Synthesis and their electrocatalytic determination of nitrite

    International Nuclear Information System (INIS)

    Microspheres with multilevel structure are widely used as removable catalysts, adsorbents, drug carriers and imaging contrast agents due to their hierarchical porosity. In this paper a facile wet chemical method for the synthesis of hierarchically nanostructured CuO chains assembled with small nanorods is reported. The as prepared nanomaterial is characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HRTEM). The autocatalytic response to nitrite ions is also carried out, which exhibits a wide linear range (0.004-3.7 mM), sound sensitivity (177.9 μA mg-1 dL-1 cm-2), highly reproducible response (R.S.D. of 2.0%), and an excellent long-term stability. The good analytical performance, low cost and straightforward preparation method make this novel electrode material promising for the development of effective nitrite sensors.

  12. Reaction of nitrite ion with hydroxylamine-N-sulfonate in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Oblath, S.B.; Markowitz, S.S.; Novakov, T.; Chang, S.G.

    1983-02-16

    The reaction between nitrite ion and hydroxylamine-N-sulfonate (HAMS) has been investigated in aqueous solutions; nitrous oxide and sulfate ions are the major products. The reaction kinetics exhibit first-order dependence on nitrite ion, second-order dependence on hydrogen ion in the pH region of 4-5, and between zero- and first-order dependence on HAMS, depending on the concentration. An activation energy of 30 kJ/mol was determined for the reaction in the temperature range of 10-40/sup 0/C. The ionic strength dependence was studied in the range of 0.2-1.5 M. Oxalate, tartrate, and phthalate buffer systems were found to enhance the rate of reaction to varying degrees. An empirical rate law and the determined rate constants are reported. The results are examined in terms of a mechanism that consists of the nitrosation of HAMS, followed by a decomposition into products.

  13. A New Perspective on Microbes Formerly Known as Nitrite-Oxidizing Bacteria.

    Science.gov (United States)

    Daims, Holger; Lücker, Sebastian; Wagner, Michael

    2016-09-01

    Nitrite-oxidizing bacteria (NOB) catalyze the second step of nitrification, nitrite oxidation to nitrate, which is an important process of the biogeochemical nitrogen cycle. NOB were traditionally perceived as physiologically restricted organisms and were less intensively studied than other nitrogen-cycling microorganisms. This picture is in contrast to new discoveries of an unexpected high diversity of mostly uncultured NOB and a great physiological versatility, which includes complex microbe-microbe interactions and lifestyles outside the nitrogen cycle. Most surprisingly, close relatives to NOB perform complete nitrification (ammonia oxidation to nitrate) and this finding will have far-reaching implications for nitrification research. We review recent work that has changed our perspective on NOB and provides a new basis for future studies on these enigmatic organisms. PMID:27283264

  14. 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.

  15. 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.

  16. Lactoferrin and transferrin fragments react with nitrite to form an inhibitor of Bacillus cereus spore outgrowth.

    OpenAIRE

    Custer, M C; Hansen, J N

    1983-01-01

    Tryptone is a pancreatic digest of casein which contains a heterogeneous mixture of substances that react with nitrite when heated in the presence of sodium thioglycolate to form a bacteriostatic agent which inhibits outgrowth of Bacillus cereus T spores. The substances which are precursors to the bacteriostatic agent can be fractionated on the basis of molecular size and charge and have properties which indicate that they are fragments of lactoferrin, an iron-binding glycoprotein. The bacter...

  17. Nitric oxide, nitrite, and Fnr regulation of hmp (flavohemoglobin) gene expression in Escherichia coli K-12.

    OpenAIRE

    Poole, R.K.; Anjum, M F; Membrillo-Hernández, J; Kim, S O; Hughes, M N; Stewart, V

    1996-01-01

    Escherichia coli possesses a soluble flavohemoglobin, with an unknown function, encoded by the hmp gene. A monolysogen containing an hmp-lacZ operon fusion was constructed to determine how the hmp promoter is regulated in response to heme ligands (O2, NO) or the presence of anaerobically utilized electron acceptors (nitrate, nitrite). Expression of the phi (hmp-lacZ)1 fusion was similar during aerobic growth in minimal medium containing glucose, glycerol, maltose, or sorbitol as a carbon sour...

  18. NMR study of reactions between Pd, Ru, and Rh nitrite complexes and sulfamic acid

    International Nuclear Information System (INIS)

    Interaction of Pd, Ru and Rh nitrite complexes with sulfamic acid was studied by the method of 14N, 15N and 17O NMR. Reference of chemical shifts was made, prevailing complex forms being ascertained. It was established that cis-nitroaquacomplexes are products of the interaction at room temperature. Coordination of sulfaminate-ion during long-term allowance to stand or during heating of the solutions was revealed

  19. Ammonium removal from municipal wastewater with application of ion exchange and partial nitritation/Anammox process

    OpenAIRE

    Malovanyy, Andriy

    2014-01-01

    Nitrogen removal from municipal wastewater with application of Anammox process offers cost reduction, especially if it is combined with maximal use of organic content of wastewater for biogas production. In this study a new technology is proposed, which is based on ammonium concentration from municipal wastewater by ion exchange followed by biological removal of ammonium from the concentrated stream by partial nitritation/Anammox process. In experiments on ammonium concentration four the most...

  20. Diversity, abundance and expression of nitrite reductase (nirK)-like genes in marine thaumarchaea

    OpenAIRE

    Lund, Marie B; Smith, Jason M.; Francis, Christopher A.

    2012-01-01

    Ammonia-oxidizing archaea (AOA) are widespread and abundant in aquatic and terrestrial habitats and appear to have a significant impact on the global nitrogen cycle. Like the ammonia-oxidizing bacteria, AOA encode a gene homologous to copper-containing nitrite reductases (nirK), which has been studied very little to date. In this study, the diversity, abundance and expression of thaumarchaeal nirK genes from coastal and marine environments were investigated using two mutually excluding primer...

  1. A Nitrospira metagenome illuminates the physiology and evolution of globally important nitrite-oxidizing bacteria

    OpenAIRE

    Lücker, Sebastian; Wagner, Michael; Maixner, Frank; Pelletier, Eric; Koch, Hanna; Vacherie, Benoit; Rattei, Thomas; Damsté, Jaap S. Sinninghe; Spieck, Eva; Le Paslier, Denis; Daims, Holger

    2010-01-01

    Nitrospira are barely studied and mostly uncultured nitrite-oxidizing bacteria, which are, according to molecular data, among the most diverse and widespread nitrifiers in natural ecosystems and biological wastewater treatment. Here, environmental genomics was used to reconstruct the complete genome of “Candidatus Nitrospira defluvii” from an activated sludge enrichment culture. On the basis of this first-deciphered Nitrospira genome and of experimental data, we show that Ca. N. defluvii diff...

  2. Chemical properties population of nitrites oxidizers, urease and phosphatase activities in sewage sludge-amended soils

    OpenAIRE

    Bonmati Pont, Manuel; Pujolà Cunill, Montserrat; Saña Vilaseca, Josep; Soliva Torrentó, Montserrat; Felipó, Ma. Teresa (María Teresa); Garau, M; B. Ceccanti; P. Nannipieri

    1985-01-01

    The aim of this work has been to determine the effect of sterilized and non-sterilized, aerobically or anaerobically digested sewage sludges on urease and phosphatase aetivities, on populations of nitrite oxidizers and on some chemical properties in laboratory conditions and for long incubation periods. Both urease an phosphatase activities were affected when anaerobic sludges were added to the soil. The inhibitory effects on both enzyme activities attributed to the presence of...

  3. 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.

  4. Formation and mitigation of N-nitrosamines in nitrite preserved cooked sausages

    OpenAIRE

    Herrmann, Susan Strange; Granby, Kit; Duedahl-Olesen, Lene

    2015-01-01

    Literature on formation and mitigation of N-nitrosamine (NA) and especially non-volatile NA (NVNA) in meat products is scarce and the present study is therefore a relevant contribution to the field. We found positive correlation between the levels of N-nitrosopiperidine (NPIP), N-nitrosohydroxyproline (NHPRO), N-nitrosoproline (NPRO), N-nitrosothiazolidine-4-carboxylic acid (NTCA) and N-nitroso-2-methyl-thiazolidine-4-carboxylic acid (NMTCA) and the amount of nitrite added to cooked pork saus...

  5. Plasma Levels of Nitrite and Nitrate in Early and Recent Classes of Fish

    OpenAIRE

    Williams, Donna A.; Flood, Mary H; Lewis, Debra A; Virginia M Miller; Krause, William J

    2008-01-01

    The stable metabolite of nitric oxide in plasma is NOx, the sum of nitrite plus nitrate. Measures of plasma NOx may provide information about the nitric oxide tonus of the entire endothelium including capillary microvessels. Although data are available for mammalian species, plasma NOx measurements in early vertebrate species are scarce. The purpose of this study was to test the hypothesis that plasma NOx would be similar to the NOx in the water environment for fish in early classes (Agnatha ...

  6. Effect of omeprazole on intragastric bacterial counts, nitrates, nitrites, and N-nitroso compounds.

    OpenAIRE

    Verdu, E; Viani, F.; Armstrong, D; Fraser, R; Siegrist, H. H.; Pignatelli, B.; Idström, J P; Cederberg, C; Blum, A L; Fried, M

    1994-01-01

    Previous studies have suggested that profound inhibition of gastric acid secretion may increase exposure to potentially carcinogenic N-nitroso compounds. The aim of this study was to find out if the proton pump inhibitor omeprazole (20 mg daily) is associated with increased concentrations of potentially carcinogenic N-nitroso compounds in gastric juice. The volume of gastric contents, number of bacteria, and concentrations of nitrates, nitrites, and N-nitroso compounds was determined in gastr...

  7. Dietary Nitrates, Nitrites, and Nitrosamines Intake and the Risk of Gastric Cancer: A Meta-Analysis

    OpenAIRE

    Peng Song; Lei Wu; Wenxian Guan

    2015-01-01

    The potential associations between dietary consumption of nitrates, nitrites, and nitrosamines and gastric cancer risk have been investigated by several studies, but yielded inconclusive results. We conducted a meta-analysis to provide a quantitative assessment of their relationships. Relevant articles were identified by a systematic literature searching of PubMed and Embase databases prior to August 2015. Random-effects models were employed to pool the relative risks. A total of 22 articles ...

  8. Serum nitrate and nitrite levels in patients with rheumatoid arthritis, ankylosing spondylitis, and osteoarthritis

    OpenAIRE

    Ersoy, Y.; Ozerol, E; Baysal, O; Temel, I; MacWalter, R; Meral, U; Altay, Z

    2002-01-01

    Methods: Thirty five patients with RA, 32 patients with AS, and 36 patients with OA were entered into this study. In addition, 30 healthy volunteers acted as a control group. Concentrations of nitrate and nitrite in serum were determined by direct and indirect Griess reactions. C reactive protein and erythrocyte sedimentation rate levels were determined as markers of systemic activity of disease (SAD) in RA and AS groups.

  9. Relationship between Nitrite Reduction and Active Phosphate Uptake in the Phosphate-Accumulating Denitrifier Pseudomonas sp. Strain JR 12

    OpenAIRE

    Barak, Yoram; van Rijn, Jaap

    2000-01-01

    Phosphate uptake by the phosphate-accumulating denitrifier Pseudomonas sp. JR12 was examined with different combinations of electron and carbon donors and electron acceptors. Phosphate uptake in acetate-supplemented cells took place with either oxygen or nitrate but did not take place when nitrite served as the final electron acceptor. Furthermore, nitrite reduction rates by this denitrifier were shown to be significantly reduced in the presence of phosphate. Phosphate uptake assays in the pr...

  10. NasFED Proteins Mediate Assimilatory Nitrate and Nitrite Transport in Klebsiella oxytoca (pneumoniae) M5al

    OpenAIRE

    Wu, Qitu; Stewart, Valley

    1998-01-01

    Klebsiella oxytoca can use nitrate and nitrite as sole nitrogen sources. The enzymes required for nitrate and nitrite assimilation are encoded by the nasFEDCBA operon. We report here the complete nasFED sequence. Sequence comparisons indicate that the nasFED genes encode components of a conventional periplasmic binding protein-dependent transport system consisting of a periplasmic binding protein (NasF), a homodimeric intrinsic membrane protein (NasE), and a homodimeric ATP-binding cassette (...

  11. Epithelial ovarian cancer and exposure to dietary nitrate and nitrite in the NIH-AARP Diet and Health Study

    OpenAIRE

    Aschebrook-Kilfoy, Briseis; Ward, Mary H.; Gierach, Gretchen L; Schatzkin, Arthur; Hollenbeck, Albert R; Sinha, Rashmi; Cross, Amanda J

    2012-01-01

    Ovarian cancer is a leading cause of cancer death among women in the United States and it has the highest mortality rate of all gynecologic cancers. Internationally, there is a five-fold variation in incidence and mortality of ovarian cancer, which suggests a role for environmental factors, including diet. Nitrate and nitrite are found in various food items and they are precursors of N-nitroso compounds, which are known carcinogens in animal models. We evaluated dietary nitrate and nitrite in...

  12. Determination of nitrate and nitrite in dairy samples by sequential injection using an in-line cadmium-reducing column

    OpenAIRE

    Lima, M.J. Reis; Fernandes, Sílvia M.V.; Rangel, António O.S.S.

    2006-01-01

    A sequential injection analysis (SIA) system for the spectrophotometric determination of nitrate in dairy samples was developed. A test portion was aspirated into a carrier solution containing ethylendiaminetetracetic acid (EDTA) and ammonium buffer, which flowed into a copperized cadmium reduction column installed in-line for the determination of the nitrate plus nitrite contents of samples. For the nitrite determination, another test portion of sample was aspirated and directly sen...

  13. 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 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. PMID:26735043

  14. Elucidating the Roles of Conserved Active Site Amino Acids in the Escherichia coli Cytochrome c Nitrite Reductase

    OpenAIRE

    Lockwood, Colin

    2013-01-01

    The periplasmic cytochrome c nitrite reductase NrfA is a homodimeric protein containing ten c-type cytochromes. NrfA catalyses the six electron reduction of nitrite to ammonia which in turn facilitates anaerobic respiration. NrfA also reduces nitric oxide and hydroxylamine to ammonium. The reduction of substrate is carried out at the distal position of a lysine ligated heme and in an active site cavity dominated by a conserved catalytic triad of histidine, tyrosine and arginine...

  15. 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.

  16. Maternal dietary intake of nitrates, nitrites and nitrosamines and selected birth defects in offspring: a case-control study

    OpenAIRE

    Huber, John C.; Brender, Jean D; Zheng, Qi; Sharkey, Joseph R; Vuong, Ann M; Shinde, Mayura U; Griesenbeck, John S; Suarez, Lucina; Langlois, Peter H.; Canfield, Mark A.; Romitti, Paul A.; Weyer, Peter J.

    2013-01-01

    Background Dietary intake of nitrates, nitrites, and nitrosamines can increase the endogenous formation of N-nitroso compounds in the stomach. Results from animal studies suggest that these compounds might be teratogenic. We examined the relationship between maternal dietary intake of nitrates, nitrites (including plant and animal sources as separate groups), and nitrosamines and several types of birth defects in offspring. Methods For this population-based case–control study, data from a 58-...

  17. Development of estimates of dietary nitrates, nitrites, and nitrosamines for use with the short willet food frequency questionnaire

    OpenAIRE

    Rene Antonio A; Sharkey Joseph R; Huber John C; Steck Michelle D; Griesenbeck John S; Brender Jean D

    2009-01-01

    Abstract Background Studies have suggested that nitrates, nitrites, and nitrosamines have an etiologic role in adverse pregnancy outcomes and chronic diseases such as cancer. Although an extensive body of literature exists on estimates of these compounds in foods, the extant data varies in quality, quantified estimates, and relevance. Methods We developed estimates of nitrates, nitrites, and nitrosamines for food items listed in the Short Willet Food Frequency Questionnaire (WFFQ) as adapted ...

  18. 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. PMID:27154650

  19. Structure of octaheme cytochrome c nitrite reductase from Thioalkalivibrio nitratireducens in a complex with phosphate

    International Nuclear Information System (INIS)

    Octaheme cytochrome c nitrite reductase from Thioalkalivibrio nitratireducens (TvNiR) catalyzes the reduction of nitrite and hydroxylamine to ammonia. The structures of the free enzyme and of the enzyme in complexes with the substrate (nitrite ion) and the inhibitor (azide ion) have been solved previously. In this study we report the structures of the oxidized complex of TvNiR with phosphate and of this complex reduced by europium(II) chloride (1.8- and 2.0-A resolution, the R factors are 15.9 and 16.7%, respectively) and the structure of the enzyme in the complex with cyanide (1.76-A resolution, the R factor is 16.5%), which was prepared by soaking a crystal of the oxidized phosphate complex of TvNiR. In the active site of the enzyme, the phosphate ion binds to the iron ion of the catalytic heme and to the side chains of the catalytic residues Arg131, Tyr303, and His361. The cyanide ion is coordinated to the heme-iron ion and is hydrogen bonded to the residue His361. In the structure of reduced TvNiR, the phosphate ion is bound in the same manner as in the structure of oxidized TvNiR, and the ninecoordinated europium ion is located on the surface of one of the crystallographically independent monomers of the enzyme.

  20. Structural basis for dynamic mechanism of nitrate/nitrite antiport by NarK

    Science.gov (United States)

    Fukuda, Masahiro; Takeda, Hironori; Kato, Hideaki E.; Doki, Shintaro; Ito, Koichi; Maturana, Andrés D.; Ishitani, Ryuichiro; Nureki, Osamu

    2015-05-01

    NarK belongs to the nitrate/nitrite porter (NNP) family in the major facilitator superfamily (MFS) and plays a central role in nitrate uptake across the membrane in diverse organisms, including archaea, bacteria, fungi and plants. Although previous studies provided insight into the overall structure and the substrate recognition of NarK, its molecular mechanism, including the driving force for nitrate transport, remained elusive. Here we demonstrate that NarK is a nitrate/nitrite antiporter, using an in vitro reconstituted system. Furthermore, we present the high-resolution crystal structures of NarK from Escherichia coli in the nitrate-bound occluded, nitrate-bound inward-open and apo inward-open states. The integrated structural, functional and computational analyses reveal the nitrate/nitrite antiport mechanism of NarK, in which substrate recognition is coupled to the transport cycle by the concomitant movement of the transmembrane helices and the key tyrosine and arginine residues in the substrate-binding site.

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

    International Nuclear Information System (INIS)

    Nitrite (NO2-), a highly reactive chemical species, accumulates in coastal waters as a result of pollution with nitrogenous waste and/or an imbalance in the bacterial processes of nitrification and denitrification. The present study probed 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 the cytochrome P450-dependent biotransformation activity determined as 7-ethoxyresorufin-O-deethylase (EROD), by nearly 36% compared to the value observed in the absence of NO2- (50.2 ± 6.74 pmol resorufin min-1 g-1 liver). Fixed wavelength fluorescence measurements in bile revealed maximum enhancement to have occurred in the metabolites of benzo[a]pyrene, a carcinogenic PAH. Lasting, sublethal physiological deterioration was apparent in fish exposed simultaneously to an oil refinery effluent and NO2-, from the unremittingly decreasing liver somatic index, even after the withdrawal of the contaminants. - Nitrite increased formation of carcinogenic PAH metabolites in fish

  2. Partial nitritation and o-cresol removal with aerobic granular biomass in a continuous airlift reactor.

    Science.gov (United States)

    Jemaat, Zulkifly; Suárez-Ojeda, María Eugenia; Pérez, Julio; Carrera, Julián

    2014-01-01

    Several chemical industries produce wastewaters containing both, ammonium and phenolic compounds. As an alternative to treat this kind of complex industrial wastewaters, this study presents the simultaneous partial nitritation and o-cresol biodegradation in a continuous airlift reactor using aerobic granular biomass. An aerobic granular sludge was developed in the airlift reactor for treating a high-strength ammonium wastewater containing 950 ± 25 mg N-NH4(+) L(-1). Then, the airlift reactor was bioaugmented with a p-nitrophenol-degrading activated sludge and o-cresol was added progressively to the ammonium feed to achieve 100 mg L(-1). The results showed that stable partial nitritation and full biodegradation of o-cresol were simultaneously maintained obtaining a suitable effluent for a subsequent anammox reactor. Moreover, two o-cresol shock-load events with concentrations of 300 and 1000 mg L(-1) were applied to assess the capabilities of the system. Despite these shock load events, the partial nitritation process was kept stable and o-cresol was totally biodegraded. Fluorescence in situ hybridization technique was used to identify the heterotrophic bacteria related to o-cresol biodegradation and the ammonia oxidising bacteria along the granules. PMID:24140352

  3. Optimization of partial nitritation in a continuous flow internal loop airlift reactor.

    Science.gov (United States)

    Jin, Ren-Cun; Xing, Bao-Shan; Ni, Wei-Min

    2013-11-01

    In the present study, the performance of the partial nitritation (PN) process in a continuous flow internal loop airlift reactor was optimized by applying the response surface method (RSM). The purpose of this work was to find the optimal combination of influent ammonium (NH4(+)-Ninf), dissolved oxygen (DO) and the alkalinity/ammonium ratio (Alk/NH4(+)-N) with respect to the effluent nitrite to ammonium molar ratio and nitrite accumulation ratio. Based on the RSM results, the reduced cubic model and the quadratic model developed for the responses indicated that the optimal conditions were a DO content of 1.1-2.1 mg L(-1), an Alk/NH4(+)-N ratio of 3.30-5.69 and an NH4(+)-Ninf content of 608-1039 mg L(-1). The results of confirmation trials were close to the predictions of the developed models. Furthermore, three types of alkali were comparatively explored for use in the PN process, and bicarbonate was found to be the best alkalinity source. PMID:24012847

  4. The nasFEDCBA operon for nitrate and nitrite assimilation in Klebsiella pneumoniae M5al.

    Science.gov (United States)

    Lin, J T; Goldman, B S; Stewart, V

    1994-05-01

    Klebsiella pneumoniae can use nitrate and nitrite as sole nitrogen sources through the nitrate assimilation pathway. We previously identified structural genes for assimilatory nitrate and nitrite reductases, nasA and nasB, respectively. We report here our further identification of four genes, nasFEDC, upstream of the nasBA genes. The nasFEDCBA genes probably form an operon. Mutational and complementation analyses indicated that both the nasC and nasA genes are required for nitrate assimilation. The predicted NASC protein is homologous to a variety of NADH-dependent oxidoreductases. Thus, the NASC protein probably mediates electron transfer from NADH to the NASA protein, which contains the active site for nitrate reduction. The deduced NASF, NASE, and NASD proteins are homologous to the NRTA, NRTB, and NRTD proteins, respectively, that are involved in nitrate uptake in Synechococcus sp. (T. Omata, X. Andriesse, and A. Hirano, Mol. Gen. Genet. 236:193-202, 1993). Mutational and complementation studies indicated that the nasD gene is required for nitrate but not nitrite assimilation. By analogy with the Synechococcus nrt genes, we propose that the nasFED genes are involved in nitrate transport in K. pneumoniae. PMID:8169203

  5. Standard addition/absorption detection microfluidic system for salt error-free nitrite determination.

    Science.gov (United States)

    Ahn, Jae-Hoon; Jo, Kyoung Ho; Hahn, Jong Hoon

    2015-07-30

    A continuous-flow microfluidic chip-based standard addition/absorption detection system has been developed for accurate determination of nitrite in water of varying salinity. The absorption detection of nitrite is made via color development using the Griess reaction. We have found the yield of the reaction is significantly affected by salinity (e.g., -12% error for 30‰ NaCl, 50.0 μg L(-1)N-NO2(-) solution). The microchip has been designed to perform standard addition, color development, and absorbance detection in sequence. To effectively block stray light, the microchip made from black poly(dimethylsiloxane) is placed on the top of a compact housing that accommodates a light-emitting diode, a photomultiplier tube, and an interference filter, where the light source and the detector are optically isolated. An 80-mm liquid-core waveguide mounted on the chip externally has been employed as the absorption detection flow cell. These designs for optics secure a wide linear response range (up to 500 μg L(-1)N-NO2(-)) and a low detection limit (0.12 μg L(-1)N-NO2(-) = 8.6 nM N-NO2(-), S/N = 3). From determination of nitrite in standard samples and real samples collected from an estuary, it has been demonstrated that our microfluidic system is highly accurate (<1% RSD, n = 3) and precise (<1% RSD, n = 3). PMID:26320643

  6. Flow injection analysis of nitrate and nitrite in commercial baby foods.

    Science.gov (United States)

    Chetty, Adrian A; Prasad, Surendra

    2016-04-15

    Commercial baby foods are an easy alternative to home-made meals especially for working parents in a nuclear family therefore it is imperative to determine the nitrate and nitrite content in commercially available baby foods varieties marketed in Fiji. A total of 108 baby food samples were analyzed for nitrate and nitrite using our standardized flow injection analysis (FIA) technique with colorimetric detection technique employing sulfanilamide and N-(1-naphthyl)ethylenediamine dihydrochloride as color reagents where the samples throughput was 38 h(-1). The commercial baby food varieties chosen comprised of vegetables, cereals, fruits and milk. The study shows that the nitrate content of the baby foods studied ranges from 2.10 to 220.67 mg kg(-1) whereas the nitrite content ranges from 0.44 to 3.67 mg kg(-1). Typical recoveries of spiked nitrate residues ranged from 92% to 106%. The study shows that the average nitrate content of commercially available baby foods in Fiji descends below the maximum level proposed by the European Union Legislation. PMID:26616981

  7. Modeling of Nitrous Oxide Production from Nitritation Reactors Treating Real Anaerobic Digestion Liquor.

    Science.gov (United States)

    Wang, Qilin; Ni, Bing-Jie; Lemaire, Romain; Hao, Xiaodi; Yuan, Zhiguo

    2016-01-01

    In this work, a mathematical model including both ammonium oxidizing bacteria (AOB) and heterotrophic bacteria (HB) is constructed to predict N2O production from the nitritation systems receiving the real anaerobic digestion liquor. This is for the first time that N2O production from such systems was modeled considering both AOB and HB. The model was calibrated and validated using experimental data from both lab- and pilot-scale nitritation reactors. The model predictions matched the dynamic N2O, ammonium, nitrite and chemical oxygen demand data well, supporting the capability of the model. Modeling results indicated that HB are the dominant contributor to N2O production in the above systems with the dissolved oxygen (DO) concentration of 0.5-1.0 mg O2/L, accounting for approximately 75% of N2O production. The modeling results also suggested that the contribution of HB to N2O production decreased with the increasing DO concentrations, from 75% at DO = 0.5 mg O2/L to 25% at DO = 7.0 mg O2/L, with a corresponding increase of the AOB contribution (from 25% to 75%). Similar to HB, the total N2O production rate also decreased dramatically from 0.65 to 0.25 mg N/L/h when DO concentration increased from 0.5 to 7.0 mg O2/L. PMID:27125491

  8. Bare and boron-doped cubic silicon carbide nanowires for electrochemical detection of nitrite sensitively.

    Science.gov (United States)

    Yang, Tao; Zhang, Liqin; Hou, Xinmei; Chen, Junhong; Chou, Kuo-Chih

    2016-01-01

    Fabrication of eletrochemical sensors based on wide bandgap compound semiconductors has attracted increasing interest in recent years. Here we report for the first time electrochemical nitrite sensors based on cubic silicon carbide (SiC) nanowires (NWs) with smooth surface and boron-doped cubic SiC NWs with fin-like structure. Multiple techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS) were used to characterize SiC and boron-doped SiC NWs. As for the electrochemical behavior of both SiC NWs electrode, the cyclic voltammetric results show that both SiC electrodes exhibit wide potential window and excellent electrocatalytic activity toward nitrite oxidation. Differential pulse voltammetry (DPV) determination reveals that there exists a good linear relationship between the oxidation peak current and the concentration in the range of 50-15000 μmoL L(-1) (cubic SiC NWs) and 5-8000 μmoL L(-1) (B-doped cubic SiC NWs) with the detection limitation of 5 and 0.5 μmoL L(-1) respectively. Compared with previously reported results, both as-prepared nitrite sensors exhibit wider linear response range with comparable high sensitivity, high stability and reproducibility. PMID:27109361

  9. 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.

  10. Modeling of Nitrous Oxide Production from Nitritation Reactors Treating Real Anaerobic Digestion Liquor

    Science.gov (United States)

    Wang, Qilin; Ni, Bing-Jie; Lemaire, Romain; Hao, Xiaodi; Yuan, Zhiguo

    2016-01-01

    In this work, a mathematical model including both ammonium oxidizing bacteria (AOB) and heterotrophic bacteria (HB) is constructed to predict N2O production from the nitritation systems receiving the real anaerobic digestion liquor. This is for the first time that N2O production from such systems was modeled considering both AOB and HB. The model was calibrated and validated using experimental data from both lab- and pilot-scale nitritation reactors. The model predictions matched the dynamic N2O, ammonium, nitrite and chemical oxygen demand data well, supporting the capability of the model. Modeling results indicated that HB are the dominant contributor to N2O production in the above systems with the dissolved oxygen (DO) concentration of 0.5–1.0 mg O2/L, accounting for approximately 75% of N2O production. The modeling results also suggested that the contribution of HB to N2O production decreased with the increasing DO concentrations, from 75% at DO = 0.5 mg O2/L to 25% at DO = 7.0 mg O2/L, with a corresponding increase of the AOB contribution (from 25% to 75%). Similar to HB, the total N2O production rate also decreased dramatically from 0.65 to 0.25 mg N/L/h when DO concentration increased from 0.5 to 7.0 mg O2/L. PMID:27125491

  11. Redox-coupled proton transfer mechanism in nitrite reductase revealed by femtosecond crystallography

    Science.gov (United States)

    Fukuda, Yohta; Tse, Ka Man; Nakane, Takanori; Nakatsu, Toru; Suzuki, Mamoru; Sugahara, Michihiro; Inoue, Shigeyuki; Masuda, Tetsuya; Yumoto, Fumiaki; Matsugaki, Naohiro; Nango, Eriko; Tono, Kensuke; Joti, Yasumasa; Kameshima, Takashi; Song, Changyong; Hatsui, Takaki; Nureki, Osamu; Murphy, Michael E. P.; Inoue, Tsuyoshi; Iwata, So; Mizohata, Eiichi

    2016-01-01

    Proton-coupled electron transfer (PCET), a ubiquitous phenomenon in biological systems, plays an essential role in copper nitrite reductase (CuNiR), the key metalloenzyme in microbial denitrification of the global nitrogen cycle. Analyses of the nitrite reduction mechanism in CuNiR with conventional synchrotron radiation crystallography (SRX) have been faced with difficulties, because X-ray photoreduction changes the native structures of metal centers and the enzyme–substrate complex. Using serial femtosecond crystallography (SFX), we determined the intact structures of CuNiR in the resting state and the nitrite complex (NC) state at 2.03- and 1.60-Å resolution, respectively. Furthermore, the SRX NC structure representing a transient state in the catalytic cycle was determined at 1.30-Å resolution. Comparison between SRX and SFX structures revealed that photoreduction changes the coordination manner of the substrate and that catalytically important His255 can switch hydrogen bond partners between the backbone carbonyl oxygen of nearby Glu279 and the side-chain hydroxyl group of Thr280. These findings, which SRX has failed to uncover, propose a redox-coupled proton switch for PCET. This concept can explain how proton transfer to the substrate is involved in intramolecular electron transfer and why substrate binding accelerates PCET. Our study demonstrates the potential of SFX as a powerful tool to study redox processes in metalloenzymes. PMID:26929369

  12. Long term partial nitritation of anaerobically treated black water and the emission of nitrous oxide.

    Science.gov (United States)

    de Graaff, M S; Zeeman, G; Temmink, H; van Loosdrecht, M C M; Buisman, C J N

    2010-04-01

    Black water (toilet water) contains half the load of organic material and the major fraction of the nutrients nitrogen and phosphorus in a household and is 25 times more concentrated, when collected with a vacuum toilet, than the total wastewater stream from a Dutch household. This research focuses on the partial nitritation of anaerobically treated black water to produce an effluent suitable to feed to the anammox process. Successful partial nitritation was achieved at 34 degrees C and 25 degrees C and for a long period (almost 400 days in the second period at 25 degrees C) without strict process control a stable effluent at a ratio of 1.3 NO(2)-N/NH(4)-N was produced which is suitable to feed to the anammox process. Nitrite oxidizers were successfully outcompeted due to inhibition by free ammonia and nitrous acid and due to fluctuating conditions in SRT (1.0-17 days) and pH (from 6.3 to 7.7) in the reactor. Microbial analysis of the sludge confirmed the presence of mainly ammonium oxidizers. The emission of nitrous oxide (N(2)O) is of growing concern and it corresponded to 0.6-2.6% (average 1.9%) of the total nitrogen load. PMID:20106499

  13. Yield of Ozone, Nitrite Nitrogen and Hydrogen Peroxide Versus Discharge Parameter Using APPJ Under Water

    Science.gov (United States)

    Chen, Bingyan; Zhu, Changping; Fei, Juntao; He, Xiang; Yin, Cheng; Wang, Yuan; Gao, Ying; Jiang, Yongfeng; Wen, Wen; Chen, Longwei

    2016-03-01

    Discharge plasma in and in contact with water can be accompanied with ultraviolet radiation and electron impact, thus can generate hydroxyl radicals, ozone, nitrite nitrogen and hydrogen peroxide. In this paper, a non-equilibrium plasma processing system was established by means of an atmospheric pressure plasma jet immersed in water. The hydroxyl intensities and discharge energy waveforms were tested. The results show that the positive and negative discharge energy peaks were asymmetric, where the positive discharge energy peak was greater than the negative one. Meanwhile, the yield of ozone and nitrite nitrogen was enhanced with the increase of both the treatment time and the discharge energy. Moreover, the pH value of treated water was reduced rapidly and maintained at a lower level. The residual concentration of hydrogen peroxide in APPJ treated water was kept at a low level. Additionally, both the efficiency energy ratio of the yield of ozone and nitrite nitrogen and that of the removal of p-nitrophenol increased as a function of discharge energy and discharge voltage. The experimental results were fully analyzed and the chemical reaction equations and the physical processes of discharges in water were given. supported by National Natural Science Foundation of China (Nos. 11274092, 11404092, 61401146), the Nantong Science and Technology Project, Nantong, China (No. BK2014024), the Open Project of Jiangsu Province Key Laboratory of Environmental Engineering, Nanjing, China (No. KF2014001), and the Fundamental Research Funds for the Central Universities of China (No. 2014B11414)

  14. 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.

  15. 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.

  16. Bare and boron-doped cubic silicon carbide nanowires for electrochemical detection of nitrite sensitively

    Science.gov (United States)

    Yang, Tao; Zhang, Liqin; Hou, Xinmei; Chen, Junhong; Chou, Kuo-Chih

    2016-04-01

    Fabrication of eletrochemical sensors based on wide bandgap compound semiconductors has attracted increasing interest in recent years. Here we report for the first time electrochemical nitrite sensors based on cubic silicon carbide (SiC) nanowires (NWs) with smooth surface and boron-doped cubic SiC NWs with fin-like structure. Multiple techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS) were used to characterize SiC and boron-doped SiC NWs. As for the electrochemical behavior of both SiC NWs electrode, the cyclic voltammetric results show that both SiC electrodes exhibit wide potential window and excellent electrocatalytic activity toward nitrite oxidation. Differential pulse voltammetry (DPV) determination reveals that there exists a good linear relationship between the oxidation peak current and the concentration in the range of 50–15000 μmoL L‑1 (cubic SiC NWs) and 5–8000 μmoL L‑1 (B-doped cubic SiC NWs) with the detection limitation of 5 and 0.5 μmoL L‑1 respectively. Compared with previously reported results, both as-prepared nitrite sensors exhibit wider linear response range with comparable high sensitivity, high stability and reproducibility.

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

    Directory of Open Access Journals (Sweden)

    Han-Seung Lee

    2015-01-01

    Full Text Available 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 ((CH32NCH2CH2OH, 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.

  18. Evaluation of Nitrate and Nitrite Reduction Kinetics Related to Liquid-Air-Interface Corrosion

    International Nuclear Information System (INIS)

    Liquid-air interface (LAI) corrosion has been a concern for causing leaks in the carbon steel tanks used for holding high-level radioactive liquid waste. To assist in understanding the mechanism of LAI corrosion, the kinetics of nitrate and nitrite reduction reactions were investigated electrochemically. Cyclic voltammetry and cathodic polarization measurements indicated that the nitrite reduction reaction exhibited faster kinetics than the nitrate reduction reaction at higher cathodic overpotential. However, the primary reduction reaction at the open circuit potential under aerated conditions was the oxygen reduction reaction. The reduction of residual oxygen was also the dominant cathodic reaction at open circuit potential in deaerated conditions. Moreover, the kinetics of oxygen reduction on steel electrodes were significantly influenced by the sample immersion conditions (partial vs. full) for aerated liquid nuclear waste simulants, but not for deaerated conditions. Lastly, the gaseous products formed during LAI corrosion were analyzed using the gas detector tube method and gas chromatography-mass spectrometry and found to contain NH3, NO2 and NO. However, the results suggested that these products were caused by the local acidification generated by the hydrolysis of cations after LAI corrosion underwent extensive propagation, instead of being directly reduced in alkaline conditions. Thus, the results in this work showed that the kinetics of nitrate and nitrite reduction could not generate a salt concentration cell in the meniscus region to cause LAI corrosion

  19. Researches concerning nitrates and nitrites accumulation in kohlrabi in the west side of Romania

    Directory of Open Access Journals (Sweden)

    Monica NEGREA

    2009-05-01

    Full Text Available In this study we followed the monitoring of nitrate and nitrite content in kohlrabi after the administration of organic and mineral fertilizers in different doses. Kohlrabi samples (GIGANT hybride for the analysis have been taken from an experimental field established in Mosnita, near Timisoara. In the experimental field to kohlrabi have been administrated three doses of synthetic fertilisers NPK N0P0K0 N30P30K30, (200 kg/ha NPK N60P60K60 (400 kg/ha NPK and N120P60K60 (400 kg/ha NPK + 180 kg/ha ammonium nitrogen and one dose of organic fertilisers (organic compost - 30 t/ha.The nitrate and nitrite content in kohlrabi was done from aqueous solution after spectrophotometric detection using the rapid tests AQUA MERCK and the Spectrophotometer SQ 118 at a wavelength of 515 and 525 nm for nitrate and nitrites. The experimental results show that the nitrate content, in samples taken from the Timis County we registered values above maximum limit allowed for kohlrabi. The highest nitrate content (2180 ppm was registered to variant V4 where the used mineral fertiliser dose was N120P60K60. This excessive accumulation appears because of the high nitrogen content N120 applied to this variant.

  20. Stable partial nitritation for low-strength wastewater at low temperature in an aerobic granular reactor.

    Science.gov (United States)

    Isanta, Eduardo; Reino, Clara; Carrera, Julián; Pérez, Julio

    2015-09-01

    Partial nitritation for a low-strength wastewater at low temperature was stably achieved in an aerobic granular reactor. A bench-scale granular sludge bioreactor was operated in continuous mode treating an influent of 70 mg N-NH4(+) L(-1) to mimic pretreated municipal nitrogenous wastewater and the temperature was progressively decreased from 30 to 12.5 °C. A suitable effluent nitrite to ammonium concentrations ratio to a subsequent anammox reactor was maintained stable during 300 days at 12.5 °C. The average applied nitrogen loading rate at 12.5 °C was 0.7 ± 0.3 g N L(-1) d(-1), with an effluent nitrate concentration of only 2.5 ± 0.7 mg N-NO3(-) L(-1). The biomass fraction of nitrite-oxidizing bacteria (NOB) in the granular sludge decreased from 19% to only 1% in 6 months of reactor operation at 12.5 °C. Nitrobacter spp. where found as the dominant NOB population, whereas Nitrospira spp. were not detected. Simulations indicated that: (i) NOB would only be effectively repressed when their oxygen half-saturation coefficient was higher than that of ammonia-oxidizing bacteria; and (ii) a lower specific growth rate of NOB was maintained at any point in the biofilm (even at 12.5 °C) due to the bulk ammonium concentration imposed through the control strategy. PMID:26001281

  1. Estimation of presynaptic calcium currents and endogenous calcium buffers at the frog neuromuscular junction with two different calcium fluorescent dyes

    OpenAIRE

    Samigullin, Dmitry; Fatikhov, Nijaz; Khaziev, Eduard; Skorinkin, Andrey; Nikolsky, Eugeny; Bukharaeva, Ellya

    2015-01-01

    At the frog neuromuscular junction, under physiological conditions, the direct measurement of calcium currents and of the concentration of intracellular calcium buffers—which determine the kinetics of calcium concentration and neurotransmitter release from the nerve terminal—has hitherto been technically impossible. With the aim of quantifying both Ca2+ currents and the intracellular calcium buffers, we measured fluorescence signals from nerve terminals loaded with the low-affinity calcium dy...

  2. Nitrite reductase is critical for Pseudomonas aeruginosa survival during co-infection with the oral commensal Streptococcus parasanguinis.

    Science.gov (United States)

    Scoffield, Jessica A; Wu, Hui

    2016-02-01

    Pseudomonas aeruginosa is the major aetiological agent of chronic pulmonary infections in cystic fibrosis (CF) patients. However, recent evidence suggests that the polymicrobial community of the CF lung may also harbour oral streptococci, and colonization by these micro-organisms may have a negative impact on P. aeruginosa within the CF lung. Our previous studies demonstrated that nitrite abundance plays an important role in P. aeruginosa survival during co-infection with oral streptococci. Nitrite reductase is a key enzyme involved in nitrite metabolism. Therefore, the objective of this study was to examine the role nitrite reductase (gene nirS) plays in P. aeruginosa survival during co-infection with an oral streptococcus, Streptococcus parasanguinis. Inactivation of nirS in both the chronic CF isolate FRD1 and acute wound isolate PAO1 reduced the survival rate of P. aeruginosa when co-cultured with S. parasanguinis. Growth of both mutants was restored when co-cultured with S. parasanguinis that was defective for H2O2 production. Furthermore, the nitrite reductase mutant was unable to kill Drosophila melanogaster during co-infection with S. parasanguinis. Taken together, these results suggest that nitrite reductase plays an important role for survival of P. aeruginosa during co-infection with S. parasanguinis. PMID:26673783

  3. A miniaturized fiber-optic colorimetric sensor for nitrite determination by coupling with a microfluidic capillary waveguide.

    Science.gov (United States)

    Xiong, Yan; Wang, Cheng-Jie; Tao, Tao; Duan, Ming; Fang, Shen-Wen; Zheng, Min

    2016-05-01

    A microfluidic-capillary-waveguide-coupled fiber-optic sensor was developed for colorimetric determination of hazardous nitrite based on the Griess-Ilosvay reaction. The sensor was modularly designed by use of a light-emitting diode as the light source, silica fiber as the light transmission element, and a capillary waveguide tube as the light reaction flow cell. With the light interacting with the azo dye generated by the Griess-Ilosvay reaction between nitrite and Griess reagents, nitrite could be determined by a colorimetric method according to Beer's law. By use of the inexpensive and micro-sized elements mentioned above, the sensor provided a new low-cost and portable method for in situ and online measurement of nitrite. The sensor had a wide linear range for nitrite from 0.02 to 1.8 mg L(-1) and a low detection limit of 7 μg L(-1) (3σ), with a relative standard deviation of 0.37% (n = 10). With a low reagent demand of 200 μL, a short response time of 6.24 s, and excellent selectivity, the sensor is environmentally friendly and has been applied to nitrite determination in different water samples. The results were compared with those obtained by conventional spectrophotometry and ion chromatography, indicating the sensor's potential for practical applications. PMID:26939671

  4. 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.

  5. The investigation of electrochemical properties for Fe3O4@Pt nanocomposites and an enhancement sensing for nitrite

    International Nuclear Information System (INIS)

    Highlights: •Electrochemical characteristics on nanoparticles and nanocomposites were compared. •The reasons for superior electrochemical activity of Fe3O4@Pt were discussed. •We report an excellent nitrite biosensor based on Fe3O4@Pt. •Electro-analytical parameters of nitrite at Fe3O4@Pt were evaluated in detail. -- Abstract: The electrochemical differences (such as charge transfer resistivity, electroactive surface, standard electron transfer rate constant, adsorption amount and analytical performance of nitrite sensor) between Fe3O4@Pt nanocomposites with two elements and core–shell structure and NPs (Fe3O4 nanoparticles and Pt nanoparticles) with single component and simple structure were investigated in detail. Above those investigations, it is believed that for the Fe3O4@Pt core–shell nanocomposites, Pt shell could provide more electro-catalytic activity while magnetic Fe3O4 core could provide larger surface area and facilitate the purification of nanocomposites. After that, Fe3O4@Pt nanocomposites modified GCE served as a nitrite sensor. Electrochemical parameters of nitrite at Fe3O4@Pt nanocomposites such as electron transfer number, electron transfer coefficient, standard heterogeneous rate constant and electron diffusion coefficient were evaluated. With the proposed electrochemical sensors, nitrite in tap water and orange juice could be detected. This investigation suggested that core–shell nanocomposites were superior for the fabrication of electrochemical sensors

  6. HONO and its potential source particulate nitrite at an urban site in North China during the cold season.

    Science.gov (United States)

    Wang, Liwei; Wen, Liang; Xu, Caihong; Chen, Jianmin; Wang, Xinfeng; Yang, Lingxiao; Wang, Wenxing; Yang, Xue; Sui, Xiao; Yao, Lan; Zhang, Qingzhu

    2015-12-15

    Characteristics and transformation of nitrous acid (HONO) and particulate nitrite were investigated with high time-resolution field measurements at an urban site in Ji'nan, China from Nov. 2013 to Jan. 2014. During the sampling period, averages of 0.35ppbv HONO and 2.08μgm(-3) fine particulate nitrite were observed. HONO and particulate nitrite exhibited similar diurnal variation patterns but differed in the time at which concentration peaks and valleys occurred. Elevated nocturnal HONO concentration peaks were mainly associated with primary emissions from vehicle exhaust and secondary formation via heterogeneous reactions of NO2. In fresh air masses dominated by vehicle emissions, the average HONO/NOx ratio was 0.58%. The nocturnal heterogeneous reactions of NO2 contributed to about half of the elevated HONO concentration peaks, with the conversion rates in the range of 0.05% to 0.96%h(-1). Meanwhile, a large amount of particulate nitrite, which greatly exceeded the concentration of the gas-phase HONO, was also produced through the heterogeneous reactions of NO2. The large yields of particulate nitrite were facilitated by abundant ammonia and particulate cations in urban Ji'nan. Notably, in the daytime, particulate nitrite acted as a potential source of HONO, especially in conditions of low humidity and acidic aerosols, which possibly has subsequent effects on photochemistry in the boundary layer. PMID:26298252

  7. Mechanism of pitting corrosion prevention by nitrite in carbon steel exposed to dilute salt solutions. 1998 annual progress report

    International Nuclear Information System (INIS)

    'The overall goal of this project is to develop a fundamental understanding of the role of nitrite in preventing the breakdown of protective oxide(s) on carbon steel and the onset of pitting. Pitting corrosion of carbon steel exposed to dilute alkaline salt solutions can be induced by nitrate, sulfate, and chloride ions and is prevented by sufficient concentration of nitrite. A significant example of this material/electrolyte system is the storage and processing of DOE''s high-level radioactive liquid waste in carbon steel tanks. Added nitrite in the waste has a considerable downstream impact on the immobilization of the waste in a stable glass form. Waste tank integrity and glass production efficiency may benefit from the fundamental understanding of nitrite''s role in preventing pitting. This report summarizes progress after approximately six months of effort in this three-year EMSP project. Initial experimental and theoretical work has focused on the electrochemical behavior of carbon steel in simplified non-radioactive solutions that simulate complex dilute radioactive waste solutions. These solutions contain corrosion-inducing species such as nitrate and chloride and the corrosion-inhibiting nitrite at moderately alkaline pHs. The electrochemical behavior of interest here is that of the open-circuit potential of the steel specimen at equilibrium in the experimental electrolyte and the measures of the steel''s passivity and passivity breakdown.'

  8. Reactivity of glass-embedded met hemoglobin derivatives towards external NO: implications for nitrite-mediated production of bioactive NO

    Science.gov (United States)

    Navati, Mahantesh S.; Friedman, Joel M.

    2009-01-01

    Many protein reactions are exceedingly difficult to dissect under standard conditions due to low concentrations of reactants and intermediates. A case in point, are several proposed reactions of hemoglobin with both nitrite and nitric oxide. In the present work, glassy matrices are used to dynamically control the rate at which externally introduced gaseous NO accesses and reacts with several different met Hb derivatives including the nitrite, nitrate and aquomet forms. This novel yet general approach reveals a clear difference between nitrite and other ligands including nitrate, water and an internal imidazole. Whereas for nitrate, water and the internal distal imidazole, the observed spectral changes indicate that NO entering the distal heme pocket is effective in displacing these ligands from the ferric heme iron. In contrast, when the ligand is nitrite, the resulting initial spectra indicate the formation of an intermediate that has distinctly ferrous-like properties. The spectrum and the response of DAF fluorescence to the presence of the intermediate is consistent with a recently proposed nitrite anhydrase reaction. This proposed intermediate is especially significant in that it represents a pathway for a nitrite-dependent catalytic process whereby Hb generates relatively long lived bioactive forms of NO such as S-nitrosoglutathione. The failure to form this intermediate either at low pH or when the glass is extensively dried is consistent with the requirement for a specific conformation of reactants and residue side chains within the distal heme pocket. PMID:19663497

  9. Gibberellic acid nitrite stimulates germination of two species of light-requiring seeds via the nitric oxide pathway.

    Science.gov (United States)

    Jovanović, Vladan; Giba, Zlatko; Djoković, Dejan; Milosavljević, Slobodan; Grubisić, Dragoljub; Konjević, Radomir

    2005-06-01

    We used two species of light-requiring seeds, Paulownia tomentosa, which have absolute light requirement (no germination in darkness), and Stellaria media seeds, which germinate in darkness to a certain extent because of presence of preformed active phytochrome, to obtain results strongly suggesting that gibberellic acid nitrite stimulates seed germination via its capability as a functional NO donor. Exogenous application of gibberellic acid nitrite stimulates gibberellin-insensitive Stellaria media seed germination in darkness as do a wide variety of NO donors. Pure gibberellic acid could replace the light requirement of P. tomentosa seeds, thus enabling them to germinate in darkness. Gibberellic acid nitrite did not have this effect. A stimulative effect from gibberellic acid nitrite could be detected only after exposure of these seeds to short, 10 min, pulse of red light. Taken together, these results suggest that gibberellic activity of gibberellic acid nitrite is lost after nitrosation but, regarding to the presence of -O-NO moiety in the molecule, gibberellic acid nitrite shares stimulative properties in seed germination with other compounds with NO-releasing properties. PMID:16154981

  10. Hemi-ordered nanoporous carbon electrode material for highly selective determination of nitrite in physiological and environmental systems

    International Nuclear Information System (INIS)

    Hemi-ordered nanoporous carbon (HONC) was obtained from a mesoporous silica template through a nano-replication method using furfuryl alcohol as the carbon source. The structure and morphology of HONC were characterized and analyzed in detail by X-ray diffraction, N2-sorption, Raman spectroscopy and transmission electron microscopy. HONC was then demonstrated as active electrode material for selective determination of nitrite in either physiological or environmental system. Well separated oxidation peaks of ascorbic acid, dopamine, uric acid and nitrite were observed in physiological system, and simultaneous discrimination of catechol, hydroquinone, resorcinol and nitrite in environmental system was also accomplished. Distinctly improved performances for selective determination of nitrite (such as significantly fast and sensitive current response with especially high selectivity) coexisted with ascorbic acid, dopamine and uric acid in the physiological system, as well as with catechol, hydroquinone and resorcinol in the environmental system were achieved at HONC electrode material. The excellent discriminating ability and high selectivity for NO2− determination were ascribed to the good electronic conductivity, unique hemi-ordered porous structure, large surface area and large number of edge plane defect sites contained on the surface of nanopore walls of HONC. Results in this work demonstrated that HONC is one of the promising catalytic electrode materials for nitrite sensor fabrication. - Highlights: • Hemi-ordered nanoporous carbon as an active electrode material • Good discriminating ability towards NO2− from physiological or environmental system • Highly selective determination of nitrite with fast and sensitive current response

  11. The role of red blood cell S-nitrosation in nitrite bioactivation and its modulation by leucine and glucose

    Science.gov (United States)

    Wajih, Nadeem; Liu, Xiaohua; Shetty, Pragna; Basu, Swati; Wu, Hanzhi; Hogg, Neil; Patel, Rakesh P.; Furdui, Cristina M.; Kim-Shapiro, Daniel B.

    2016-01-01

    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. PMID:27156251

  12. Effects of nitrite exposure on functional haemoglobin levels, bimodal respiration, and swimming performance in the facultative air-breathing fish Pangasianodon hypophthalmus

    Energy Technology Data Exchange (ETDEWEB)

    Lefevre, Sjannie, E-mail: sjannie.lefevre@biology.au.dk [Zoophysiology, Department of Biological Sciences, Aarhus University, Aarhus (Denmark); Jensen, Frank B. [Department of Biology, University of Southern Denmark, Odense (Denmark); Huong, Do.T.T. [College of Aquaculture and Fisheries, Can Tho University, Can Tho City (Viet Nam); Wang, Tobias [Zoophysiology, Department of Biological Sciences, Aarhus University, Aarhus (Denmark); Phuong, Nguyen T. [College of Aquaculture and Fisheries, Can Tho University, Can Tho City (Viet Nam); Bayley, Mark [Zoophysiology, Department of Biological Sciences, Aarhus University, Aarhus (Denmark)

    2011-07-15

    In this study we investigated nitrite (NO{sub 2}{sup -}) effects in striped catfish, a facultative air-breather. Fish were exposed to 0, 0.4, and 0.9 mM nitrite for 0, 1, 2, 4, and 7 days, and levels of functional haemoglobin, methaemoglobin (metHb) and nitrosyl haemoglobin (HbNO) were assessed using spectral deconvolution. Plasma concentrations of nitrite, nitrate, chloride, potassium, and sodium were also measured. Partitioning of oxygen consumption was determined to reveal whether elevated metHb (causing functional hypoxia) induced air-breathing. The effects of nitrite on maximum oxygen uptake (MO{sub 2max}) and critical swimming speed (U{sub crit}) were also assessed. Striped catfish was highly tolerant to nitrite exposure, as reflected by a 96 h LC{sub 50} of 1.65 mM and a moderate nitrite uptake into the blood. Plasma levels of nitrite reached a maximum after 1 day of exposure, and then decreased, never exceeding ambient levels. MetHb, HbNO and nitrate (a nitrite detoxification product) also peaked after 1 day and then decreased. Only high levels of nitrite and metHb caused reductions in MO{sub 2max} and U{sub crit}. The response of striped catfish contrasts with that seen in most other fish species and discloses efficient mechanisms of combating nitrite threats. Furthermore, even though striped catfish is an efficient air-breather, this species has the ability to sustain aerobic scope and swimming performance without air-breathing, even when faced with nitrite-induced reductions in blood oxygen carrying capacity. Our study is the first to confirm that high levels of nitrite and metHb reduce MO{sub 2max} and thereby aerobic scope, while more moderate elevations fail to do so. Further studies are needed to elucidate the mechanisms underlying the low nitrite accumulation in striped catfish.

  13. Effects of nitrite exposure on functional haemoglobin levels, bimodal respiration, and swimming performance in the facultative air-breathing fish Pangasianodon hypophthalmus

    International Nuclear Information System (INIS)

    In this study we investigated nitrite (NO2-) effects in striped catfish, a facultative air-breather. Fish were exposed to 0, 0.4, and 0.9 mM nitrite for 0, 1, 2, 4, and 7 days, and levels of functional haemoglobin, methaemoglobin (metHb) and nitrosyl haemoglobin (HbNO) were assessed using spectral deconvolution. Plasma concentrations of nitrite, nitrate, chloride, potassium, and sodium were also measured. Partitioning of oxygen consumption was determined to reveal whether elevated metHb (causing functional hypoxia) induced air-breathing. The effects of nitrite on maximum oxygen uptake (MO2max) and critical swimming speed (Ucrit) were also assessed. Striped catfish was highly tolerant to nitrite exposure, as reflected by a 96 h LC50 of 1.65 mM and a moderate nitrite uptake into the blood. Plasma levels of nitrite reached a maximum after 1 day of exposure, and then decreased, never exceeding ambient levels. MetHb, HbNO and nitrate (a nitrite detoxification product) also peaked after 1 day and then decreased. Only high levels of nitrite and metHb caused reductions in MO2max and Ucrit. The response of striped catfish contrasts with that seen in most other fish species and discloses efficient mechanisms of combating nitrite threats. Furthermore, even though striped catfish is an efficient air-breather, this species has the ability to sustain aerobic scope and swimming performance without air-breathing, even when faced with nitrite-induced reductions in blood oxygen carrying capacity. Our study is the first to confirm that high levels of nitrite and metHb reduce MO2max and thereby aerobic scope, while more moderate elevations fail to do so. Further studies are needed to elucidate the mechanisms underlying the low nitrite accumulation in striped catfish.

  14. Variability of calcium absorption

    International Nuclear Information System (INIS)

    Variability in calcium absorption was estimated in three groups of normal subjects in whom Ca absorption was measured by standard isotopic-tracer methods at interstudy intervals ranging from 1 to 4 mo. Fifty absorption tests were performed in 22 subjects. Each was done in the morning after an overnight fast with an identical standard breakfast containing a Ca load of approximately 250 mg. Individual fractional absorption values were normalized to permit pooling of the data. The coefficient of variation (CVs) for absorption for the three groups ranged from 10.57 to 12.79% with the size of the CV increasing with interstudy duration. One other published study presenting replicate absorption values was analyzed in a similar fashion and was found to have a CV of absorption of 9.78%. From these data we estimate that when the standard double-isotope method is used to measure Ca absorption there is approximately 10% variability around any given absorption value within an individual human subject and that roughly two-thirds of this represents real biological variability in absorption

  15. Calcium-sensitive immunoaffinity chromatography

    DEFF Research Database (Denmark)

    Henriksen, Maiken L; Lindhardt Madsen, Kirstine; Skjoedt, Karsten;

    2014-01-01

    homogeneity may be impossible due to contamination with abundant antigens. In this study, we purified the scarce, complement-associated plasma protein complex, collectin LK (CL-LK, complex of collectin liver 1 and kidney 1), by immunoaffinity chromatography using a calcium-sensitive anti-collectin-kidney-1 m......Ab. This antibody was characterized by binding to CL-LK at hypo- and physiological calcium concentrations and dissociated from CK-LK at hyperphysiological concentrations of calcium. We purified CL-LK from plasma to a purity of 41% and a yield of 38%, resulting in a purification factor of more than 88......,000 in a single step. To evaluate the efficiency of this new purification scheme, we purified CL-LK using the same calcium-sensitive mAb in combination with acidic elution buffer and by using calcium-dependent anti-CL-K1 mAbs in combination with EDTA elution buffer. We found that calcium...

  16. 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

  17. Acidified nitrite inhibits proliferation of Listeria monocytogenes - Transcriptional analysis of a preservation method.

    Science.gov (United States)

    Müller-Herbst, Stefanie; Wüstner, Stefanie; Kabisch, Jan; Pichner, Rohtraud; Scherer, Siegfried

    2016-06-01

    Sodium nitrite (NaNO2) is added as a preservative during raw meat processing such as raw sausage production to inhibit growth of pathogenic bacteria. In the present study it was shown in challenge assays that the addition of sodium nitrite indeed inhibited growth and survival of Listeria monocytogenes in short-ripened spreadable raw sausages. Furthermore, in vitro growth analyses were performed, which took into account combinations of various parameters of the raw sausage ripening process like temperature, oxygen availability, pH, NaCl concentration, and absence or presence of NaNO2. Data based on 300 growth conditions revealed that the inhibitory effect of nitrite was most prominent in combination with acidification, a combination that is also achieved during short-ripened spreadable raw sausage production. At pH6.0 and below, L. monocytogenes was unable to replicate in the presence of 200mg/l NaNO2. During the adaptation of L. monocytogenes to acidified nitrite stress (pH6.0, 200mg/l NaNO2) in comparison to acid exposure only (pH6.0, 0mg/l NaNO2), a massive transcriptional adaptation was observed using microarray analyses. In total, 202 genes were up-regulated and 204 genes were down-regulated. In accordance with growth inhibition, a down-regulation of genes encoding for proteins which are involved in central cellular processes, like cell wall/membrane/envelope biogenesis, translation and ribosomal structure and biogenesis, transcription, and replication, recombination and repair, was observed. Among the up-regulated genes the most prominent group belonged to poorly characterized genes. A considerable fraction of the up-regulated genes has been shown previously to be up-regulated intracellularly in macrophages, after exposure to acid shock or to be part of the SigB regulon. These data indicate that the adaptation to acidified nitrite partly overlaps with the adaptation to stress conditions being present during host colonization. PMID:27017279

  18. 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...... 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...

  19. Control of H2S emission from swine manure using Na-nitrite and Na-molybdate

    International Nuclear Information System (INIS)

    Biogenic production of hydrogen sulphide (H2S) in oil reservoirs (souring) has been shown to be controlled effectively using nitrite and molybdate salts. In the present work the effects of addition of nitrite and molybdate on reducing the emission of H2S from swine manure slurry was investigated in the laboratory and semi-pilot scale systems. Addition of 80 mM nitrite or 2 mM molybdate (final concentration in the manure slurry) to fresh manure in the laboratory scale closed systems (125 mL and 4 L) reduced the concentration of H2S in the headspace gas from 1500 μL L-1 to 10 μL L-1 which maintained during the remaining period of trials (40-60 days). With aged manure, similar results were achieved with a lower level of nitrite (10 mM). Simultaneous or sequential additions of nitrite and molybdate to fresh manure had similar effects. Contrary to the systems simulating biological conditions in oil reservoirs in which simultaneous addition of nitrite and molybdate has been reported to have a synergistic effect, no synergism was observed when nitrite and molybdate were added to the manure simultaneously. Experiments with fresh manure slurry in the semi-pilot scale systems (200 L) confirmed the effectiveness of this approach in which addition of 80 mM nitrite or 2 mM molybdate or a combination of 80 mM nitrite and 2 mM molybdate decreased the concentration of the H2S in the headspace gas from an initial value of 500 μL L-1 to a low level in the range 2-25 μL L-1 and maintained these low levels during the remaining period of trials (16 days). The concentration of ammonia (NH3) in the headspace gas of the treated systems was similar to that observed in the control system (untreated), indicating that the treatment did not have an effect on the level of present NH3. Although the addition of nitrite or molybdate reduced emissions of H2S from swine manure and the associated health and safety concerns, it had little impact on the intensity of odour in the headspace gas

  20. "Caged calcium" in Aplysia pacemaker neurons. Characterization of calcium-activated potassium and nonspecific cation currents

    OpenAIRE

    1989-01-01

    We have studied calcium-activated potassium current, IK(Ca), and calcium-activated nonspecific cation current, INS(Ca), in Aplysia bursting pacemaker neurons, using photolysis of a calcium chelator (nitr-5 or nitr-7) to release "caged calcium" intracellularly. A computer model of nitr photolysis, multiple buffer equilibration, and active calcium extrusion was developed to predict volume-average and front-surface calcium concentration transients. Changes in arsenazo III absorbance were used to...

  1. 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.

  2. Nitrite and Nitrate Levels of Gingival Crevicular Fluid and Saliva in Subjects with Gingivitis and Chronic Periodontitis

    Directory of Open Access Journals (Sweden)

    Ali Orkun Topcu

    2014-07-01

    Full Text Available Objectives: Nitrosative stress plays an essential role in the pathogenesis of periodontal disease. The aim of this study is to analyze the gingival crevicular fluid and saliva nitrite and nitrate levels in periodontally healthy and diseased sites. Material and Methods: A total of 60 individuals including, 20 chronic periodontitis and 20 gingivitis patients and 20 periodontally healthy controls participated in the present study. Probing depth, clinical attachment level, bleeding on probing, gingival index and plaque index were assessed, gingival crevicular fluid (GCF and saliva samples were obtained from the subjects, including 480 GCF samples and 60 unstimulated whole saliva samples. Nitrite and nitrate were analyzed by Griess reagent. Results: Total GCF nitrite levels were higher in gingivitis and periodontitis groups (1.07 [SD 0.62] nmol and 1.08 [SD 0.59] nmol than the control group (0.83 [SD 0.31] nmol (P 0.05. The difference in GCF nitrate level was not significant among the control, gingivitis and periodontitis groups (7.7 [SD 2.71] nmol, 7.51 [SD 4.16] nmol and 7.38 [SD 1.91] nmol. Saliva nitrite and nitrate levels did not differ significantly among three study groups. Saliva nitrate/nitrite ratios were higher in periodontitis and gingivitis groups than the control group. A gradual decrease in nitrate/nitrite ratio in GCF was detected with the presence of inflammation. Conclusions: It may be suggested that nitrite in gingival crevicular fluid is a better periodontal disease marker than nitrate and may be used as an early detection marker of periodontal inflammation, and that local nitrosative stress markers don’t show significant difference between the initial and advanced stages of periodontal disease.

  3. Effect of Preharvest Calcium Treatments on Sweet Cherry Fruit Quality

    OpenAIRE

    Deniz EROGUL

    2014-01-01

    In this study, the effects of different foliar calcium compounds on fruit cracking and quality of sweet cherry variety ‘0900 Ziraat’ were investigated. Calcium caseinate, calcium chloride, calcium hydroxide and calcium nitrate were used as foliar sprays. Calcium applications reduced the cracking index 38% to 66% compared to cherries that did not receive foliar treatment. The most efficient applications for decreasing cracking were calcium hydroxide and calcium chloride. Calcium chloride and c...

  4. Stochastic Simulation of Cardiac Ventricular Myocyte Calcium Dynamics and Waves

    OpenAIRE

    Tuan, Hoang-Trong Minh; Williams, George S.B.; Chikando, Aristide C.; Sobie, Eric A.; Lederer, W. Jonathan; Jafri, M. Saleet

    2011-01-01

    A three dimensional model of calcium dynamics in the rat ventricular myocyte was developed to study the mechanism of calcium homeostasis and pathological calcium dynamics during calcium overload. The model contains 20,000 calcium release units (CRUs) each containing 49 ryanodine receptors. The model simulates calcium sparks with a realistic spontaneous calcium spark rate. It suggests that in addition to the calcium spark-based leak, there is an invisible calcium leak caused by the stochastic ...

  5. A comparative study of nitrite reduction by synthetic and biogenic Fe(II-III) hydroxysalts green rusts: Evidence for hydroxyl-nitrite green rust formation as an intermediate reaction product.

    Science.gov (United States)

    Ona-Nguema, G.; Guerbois, D.; Morin, G.; Zhang, Y.; Noel, V.; Brest, J.

    2013-12-01

    The occurrence of high nitrite concentrations as a result of anthropogenic activities is an important water quality concern as it is highly toxic to human and fauna, and it is used as a nitrogen source for the assimilation process. The toxicity of nitrite is related to its transformation into carcinogenic N-nitroso compounds, which are suspected to be responsible for some gastric cancers, and to its ability to convert the hemoglobin to methaemoglobin what is then unable to fix oxygen and to transport it to the tissues, involving hypoxia and the blue-baby syndrome [1]. To reduce the adverse effect of nitrite on human health and on macroalgal blooms, any process enhancing the transformation of nitrite ions to nitrogen gas is of interest for the remediation of natural environments. To achieve this purpose the use of processes involving Fe(II)-containing minerals could be considered as one of the best options. Green-rusts are mixed Fe(II-III) layered double hydroxides commonly found in anoxic zones of natural environments such as sediments and hydromorphic soils. In such anoxic environments, green rust minerals play an important role in the biogeochemical redox cycling of iron and nitrogen, and can affect the speciation and mobility of many organic and inorganic contaminants. The present study investigates the reduction of nitrite by two synthetic and two biogenic green rusts. On the one hand, Fe(II-III) hydroxychloride and Fe(II-III) hydroxycarbonate green rusts were used as synthetic interlayer forms of GR, which are referred to as ';syn-GR(CO3)' and ';syn-GR(Cl)', respectively. On the other hand, the study was performed with biogenic Fe(II-III) hydroxycarbonate green rusts obtained from the bioreduction of two ferric precursors, either Fe(III)-oxyhydroxycarbonate or lepidocrocite; these biogenic green rusts are referred to as ';bio-GR(CO3)F' and ';bio-GR(CO3)L', respectively. For synthetic green rusts, results showed that the oxidation of both syn-GR(CO3) and syn

  6. Nitrogen and Oxygen Regulation of Bacillus subtilis nasDEF Encoding NADH-Dependent Nitrite Reductase by TnrA and ResDE

    OpenAIRE

    Nakano, Michiko M.; Hoffmann, Tamara; Zhu, Yi; Jahn, Dieter

    1998-01-01

    The nitrate and nitrite reductases of Bacillus subtilis have two different physiological functions. Under conditions of nitrogen limitation, these enzymes catalyze the reduction of nitrate via nitrite to ammonia for the anabolic incorporation of nitrogen into biomolecules. They also function catabolically in anaerobic respiration, which involves the use of nitrate and nitrite as terminal electron acceptors. Two distinct nitrate reductases, encoded by narGHI and nasBC, function in anabolic and...

  7. Penetapan Kadar Nitrit dan Nitrat dalam Kornet Daging Sapi dan Daging Sapi Burger pada Beberapa Supermarket di Kota Medan Secara Spektrofotometri Sinar Tampak

    OpenAIRE

    Harefa, Erlinawatisari

    2016-01-01

    Nitrite and nitrate in the permitted number, added in meat processing to inhibit growth of the bacteria Clostridium botulinum, maintain the red color of meat to appear attractive, as well as forming taste. But nitrite and nitrate can undergo changes during processing and storage, and can react with alkyl amines to form nitrosamines which are karsiogenik.Limit used of nitrite 125mg/kg (meat manufactured and meat preserving have maximum limit 500mg/kg. the purpose of this rese...

  8. Aging and calcium as an environmental factor.

    Science.gov (United States)

    Fujita, T

    1985-12-01

    Calcium deficiency is a constant menace to land-abiding animals, including mammals. Humans enjoying exceptional longevity on earth are especially susceptible to calcium deficiency in old age. Low calcium and vitamin D intake, short solar exposure, decreased intestinal absorption, and falling renal function with insufficient 1,25(OH)2 vitamin D biosynthesis all contribute to calcium deficiency, secondary hyperparathyroidism, bone loss and possibly calcium shift from the bone to soft tissue, and from the extracellular to the intracellular compartment, blunting the sharp concentration gap between these compartments. The consequences of calcium deficiency might thus include not only osteoporosis, but also arteriosclerosis and hypertension due to the increase of calcium in the vascular wall, amyotrophic lateral sclerosis and senile dementia due to calcium deposition in the central nervous system, and a decrease in cellular function, because of blunting of the difference in extracellular-intracellular calcium, leading to diabetes mellitus, immune deficiency and others (Fig. 6). PMID:2943880

  9. Transport of Calcium Ions into Mitochondria.

    Science.gov (United States)

    Xu, Zhaolong; Zhang, Dayong; He, Xiaolan; Huang, Yihong; Shao, Hongbo

    2016-06-01

    To uptake calcium ions of mitochondria is of significant functional connotation for cells, because calcium ions in mitochondria are involved in energy production, regulatory signals transfer, and mitochondrial permeability transition pore opening and even programmed cell death of apoptosis, further playing more roles in plant productivity and quality. Cytoplasmic calcium ions access into outer mitochondrial membrane (OMM) from voltage dependent anion-selective channel (VDAC) and were absorbed into inner mitochondrial membrane (IMM) by mitochondrial calcium uniporter (MCU), rapid mitochondrial calcium uptake (RaM) or mitochondrial ryanodine receptor (mRyR). Although both mitochondria and the mechanisms of calcium transport have been extensively studied, but there are still long-standing or even new challenges. Here we review the history and recent discoveries of the mitochondria calcium ions channel complex involved calcium assimilation, and discuss the role of calcium ions into mitochondria. PMID:27252588

  10. Optimizing calcium selective fluorimetric nanospheres.

    Science.gov (United States)

    Kisiel, Anna; Kłucińska, Katarzyna; Gniadek, Marianna; Maksymiuk, Krzysztof; Michalska, Agata

    2015-11-01

    Recently it was shown that optical nanosensors based on alternating polymers e.g. poly(maleic anhydride-alt-1-octadecene) were characterized by a linear dependence of emission intensity on logarithm of concentration over a few of orders of magnitude range. In this work we focus on the material used to prepare calcium selective nanosensors. It is shown that alternating polymer nanosensors offer competitive performance in the absence of calcium ionophore, due to interaction of the nanospheres building blocks with analyte ions. The emission increase corresponds to increase of calcium ions contents in the sample within the range from 10(-4) to 10(-1) M. Further improvement in sensitivity (from 10(-6) to 10(-1) M) and selectivity can be achieved by incorporating calcium ionophore in the nanospheres. The optimal results were obtained for core-shell nanospheres, where the core was prepared from poly(styrene-co-maleic anhydride) and the outer layer from poly(maleic anhydride-alt-1-octadecene). Thus obtained chemosensors were showing linear dependence of emission on logarithm of calcium ions concentration within the range from 10(-7) to 10(-1) M. PMID:26452839

  11. Isomorfic Substitutions of Calcium by Strontium in Calcium Hydroxyapatite

    International Nuclear Information System (INIS)

    By means of homogeneous precipitation it has been possible to synthesize crystalline solid solutions of calcium strontium hydroxyapatite from aqueous solutions. The lattice constants for the solid solutions were measured in the range Ca9Sr(PO4)6(OH)2 - CaSr9(PO4)6(OH)2. The investigations show that the discrimination of strontium against calcium is considerably smaller than reported elsewhere (1). Strontium is preferentially built into the c-axis direction of the apatite lattice

  12. Structures of genes nasA and nasB, encoding assimilatory nitrate and nitrite reductases in Klebsiella pneumoniae M5al.

    OpenAIRE

    Lin, J. T.; Goldman, B. S.; Stewart, V

    1993-01-01

    Klebsiella pneumoniae can use nitrate and nitrite as sole nitrogen sources during aerobic growth. Assimilatory nitrate and nitrite reductases convert nitrate through nitrite to ammonium. We report here the molecular cloning of the nasA and nasB genes, which encode assimilatory nitrate and nitrite reductase, respectively. These genes are tightly linked and probably form a nasBA operon. In vivo protein expression and DNA sequence analysis revealed that the nasA and nasB genes encode 92- and 104...

  13. Effect of sodium lactate /sodium diacetate in combination with sodium nitrite on physiochemical, microbial properties and sensory evaluation of cow sausage

    Directory of Open Access Journals (Sweden)

    Habib Sedghi

    2014-11-01

    Full Text Available Sodium nitrite has been always considered as one of the common additives due to its antibacterial effects on Clostridium botulinum and meat products' color, however it produces cancer creating nitrosamine. Recently, organic acids and their salts such as lactates have been employed as antimicrobial compounds. Lactates also improve organileptic properties including color, texture and taste and antioxidant properties. Sodium lactate causes to more reduction of anaerobic spore former bacteria than nitrite, inhibits botulin produced by Clostridium botulinum. Sodium lactate produces a permanent reddish pink color through reduction of deoxymygloboline and producing deoxymyoglobuline. In this study, the decrease of sodium nitrite amount from 120ppm to 15ppm by adding sodium lactate / sodium diacetate led to achieve an acceptable product. The best results revealed through adding 3.0625% of sodium lactate / sodium diacetate in combination with 30ppm sodium nitrite. Results also exhibited more reduction of pathogens' growth than nitrite, enhanced flavor slightly, but unable to produce reddish pink color as produced by nitrite. Results also exhibited that sodium lactate / diacetate cause to retard in microbial growth, reducing chemical change, enhance sensory properties, partially improvement in taste and texture. Although inappropriate color demonstrated sodium lactate / diacetate's inability in red pink color production in 4th sample (contains 15 ppm nitrite, its synergy effect in combination with sodium nitrite on nitroso myoglobuline production has been proven, led to sodium nitrite reduction in sausages.

  14. Effect of anions or foods on absolute bioavailability of calcium from calcium salts in mice by pharmacokinetics

    OpenAIRE

    Ueda, Yukari; Taira, Zenei

    2013-01-01

    We studied the absolute bioavailability of calcium from calcium L-lactate in mice using pharmacokinetics, and reviewed the absolute bioavailability of calcium from three other calcium salts in mice previously studied: calcium chloride, calcium acetate, and calcium ascorbate. The results showed that calcium metabolism is linear between intravenous administration of 15 mg/kg and 30 mg/kg, and is not affected by anions. Results after oral calcium administration of 150 mg/kg showed that the intes...

  15. Calcium release-activated calcium current in rat mast cells.

    Science.gov (United States)

    Hoth, M; Penner, R

    1993-06-01

    1. Whole-cell patch clamp recordings of membrane currents and fura-2 measurements of free intracellular calcium concentration ([Ca2+]i) were used to study the biophysical properties of a calcium current activated by depletion of intracellular calcium stores in rat peritoneal mast cells. 2. Calcium influx through an inward calcium release-activated calcium current (ICRAC) was induced by three independent mechanisms that result in store depletion: intracellular infusion of inositol 1,4,5-trisphosphate (InsP3) or extracellular application of ionomycin (active depletion), and intracellular infusion of calcium chelators (ethylene glycol bis-N,N,N',N'-tetraacetic acid (EGTA) or 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA)) to prevent reuptake of leaked-out calcium into the stores (passive depletion). 3. The activation of ICRAC induced by active store depletion has a short delay (4-14 s) following intracellular infusion of InsP3 or extracellular application of ionomycin. It has a monoexponential time course with a time constant of 20-30 s and, depending on the complementary Ca2+ buffer, a mean normalized amplitude (at 0 mV) of 0.6 pA pF-1 (with EGTA) and 1.1 pA pF-1 (with BAPTA). 4. After full activation of ICRAC by InsP3 in the presence of EGTA (10 mM), hyperpolarizing pulses to -100 mV induced an instantaneous inward current that decayed by 64% within 50 ms. This inactivation is probably mediated by [Ca2+]i, since the decrease of inward current in the presence of the fast Ca2+ buffer BAPTA (10 mM) was only 30%. 5. The amplitude of ICRAC was dependent on the extracellular Ca2+ concentration with an apparent dissociation constant (KD) of 3.3 mM. Inward currents were nonsaturating up to -200 mV. 6. The selectivity of ICRAC for Ca2+ was assessed by using fura-2 as the dominant intracellular buffer (at a concentration of 2 mM) and relating the absolute changes in the calcium-sensitive fluorescence (390 nm excitation) with the calcium current integral

  16. Noble metal catalyzed hydrogen generation from formic acid in nitrite-containing simulated nuclear waste media

    International Nuclear Information System (INIS)

    The Hanford Waste Vitrification Plant (HWVP) is being designed by the U.S. Department of Energy to immobilize high-level nuclear waste. Simulants for the HWVP feed containing the major nonradioactive components Al, Cd, Fe, Mn, Nd, Ni, Si, Zr, Na, CO32-, NO3- and NO2- were used as media to evaluate the stability of formic acid towards hydrogen evolution by the reaction HCO2H→H2+/CO2 catalyzed by the noble metals Ru, Rh, and/or Pd found in significant quantities in uranium fission products. Small-scale experiments using 40-50 mL of feed simulant in closed glass reactors (250-550 mL total volume) at 80-100 degree C were used to study the effect of nitrite and nitrate ion on the catalytic activities of the noble metals for formic acid decomposition. Reactions were monitored using gas chromatography to analyze the CO2, H2, NO, and N2O in the gas phase as a function of time. Rhodium, which was introduced as soluble RhCl3.3H2O, was found to be the most active catalyst for hydrogen generation from formic acid above nearly 80 degree C in the presence of nitrite ion in accord with earlier observations. The apparent homogeneous nature of the nitrite-promoted Rh-catalyzed formic acid decomposition is consistent with the approximate pseudo-first-order dependence of the hydrogen production rate on Rh concentration. 24 refs., 7 figs., 2 tabs

  17. Serial crystallography captures enzyme catalysis in copper nitrite reductase at atomic resolution from one crystal.

    Science.gov (United States)

    Horrell, Sam; Antonyuk, Svetlana V; Eady, Robert R; Hasnain, S Samar; Hough, Michael A; Strange, Richard W

    2016-07-01

    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. PMID:27437114

  18. Simultaneous electricity generation and pollutant removal in microbial fuel cell with denitrifying biocathode over nitrite

    International Nuclear Information System (INIS)

    Highlights: • An MFC was successfully started up using nitrite as cathodic electron acceptor. • The optimal HRT was deemed to be 8 h in this study. • The suitable temperature for power generation was found to be 20 °C. • The suitable temperature for pollutant removal was found to be 25 °C. • Free buffer led to 50% decrease of TN removal rate and power generation. - Abstract: The influences of hydraulic retention time, temperature and free buffer on the performance of short-cut denitrifying microbial fuel cell were investigated after it was successfully started up using nitrite as the cathodic electron acceptor. The results revealed that a power density of 8.3 ± 0.5 W m−3 NC was obtained after 15 days operation. The desirable hydraulic retention time was found in this study to be 8 h, with a COD removal rate of 2.117 ± 0.006 kg m−3 NC d−1 and a total nitrogen removal rate of 0.041 ± 0.002 kg m−3 NC d−1, respectively. It demonstrated that temperature had different effects on the electricity generation and pollutant removal performance of microbial fuel cell. The suitable temperature for power generation and pollutant removal was found to be 20 °C and 25 °C, respectively. Free buffer led to 50% decrease of both total nitrogen removal rate and power density of microbial fuel cell compared to that with phosphate buffer solution addition. The optimal total nitrogen removal rate obtained in the case with sodium azide addition (0.075 ± 0.008 kg m−3 NC d−1) increased by 50% as compared to that without sodium azide addition. It suggested that abolishing oxygen or inhibiting nitrite oxidizing bacteria would favor nitrogen removal

  19. Electrocatalytic Activity of Carbonized Nanostructured Polyanilines for Oxidation Reactions: Sensing of Nitrite Ions and Ascorbic Acid

    International Nuclear Information System (INIS)

    Highlights: • Carbonized PANIs prepared from various nanostructured PANI precursors • Electroanalytical performances of carbonized PANIs evaluated using voltammetry • Study of carbonized PANIs physico-chemical properties related to electroactivity • The lowest over-potential for NO2− oxidation at c-PANI (+0.87 V vs. SCE) • The lowest over-potential for ascorbic acid oxidation at both c-PANI and c-PANI-SSA - Abstract: A comparative study of the electrocatalytic activity of nitrogen-containing carbon nanomaterials, prepared by the carbonization of nanostructured polyaniline (PANI) salts, for the electrooxidation reactions is presented. Nanostructured PANI salts were synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in an aqueous solution in the presence of 5-sulfosalicylic acid (PANI-SSA), 3,5-dinitrosalicylic acid (PANI-DNSA) as well as without added acid (PANI), and subsequently carbonized to c-PANI-SSA, c-PANI-DNSA and c-PANI, respectively. Glassy carbon tip was modified with nanostructured c-PANIs and used for the investigation of sensing of nitrite and ascorbic acid in aqueous solutions as model analytes by linear sweep voltammetry. All three types of the investigated c-PANIs gave excellent response to the nitrite ions and ascorbic acid electrooxidation. The lowest peak potential for nitrite ion oxidation exhibited c-PANI (+0.87 V vs. SCE), and for ascorbic acid oxidation both c-PANI and c-PANI-SSA (ca. + 0.13 V vs. SCE). Electrochemical data were correlated with structural and textural data obtained by Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, elemental and nitrogen sorption analysis

  20. Calcium phosphate in catheter encrustation.

    Science.gov (United States)

    Cox, A J; Harries, J E; Hukins, D W; Kennedy, A P; Sutton, T M

    1987-02-01

    Encrusted catheters from nine female patients were the source of samples of deposits which were examined by X-ray diffraction, atomic absorption spectroscopy, infra-red spectroscopy and extended X-ray absorption fine structure (EXAFS) spectroscopy. In eight samples the only crystalline phase which could be clearly distinguished by X-ray diffraction was ammonium magnesium orthophosphate hexahydrate, NH4MgPO4 X 6H2O, which occurs naturally as the mineral struvite. However, atomic absorption spectroscopy revealed an appreciable concentration of calcium in all samples. Calcium phosphates have previously been detected in catheter deposits. Infra-red and EXAFS spectra were consistent with the calcium phosphate being present as a poorly crystalline hydroxyapatite. Thus the deposits appear to consist of a mixture of crystalline struvite and a form of hydroxyapatite which is not fully crystalline. PMID:3030487