Showing papers on "Nitrite published in 2009"
Karolinska Institutet1, University of Pittsburgh2, Queen Mary University of London3, University of Exeter4, University of Texas Health Science Center at Houston5, University of St Andrews6, University of California, San Diego7, Aarhus University8, University of Warwick9, University of California, Santa Barbara10, University of Birmingham11, Yeshiva University12, University of Düsseldorf13, Louisiana State University in Shreveport14, Wake Forest University15, University of Vienna16, University of Alabama at Birmingham17, Emory University18, University of Glasgow19, Cleveland Clinic20, Uppsala University21, Russian Academy of Sciences22, University of Oklahoma23, National Institutes of Health24, University of Tokushima25, Utrecht University26, Ohio State University27
TL;DR: The latest advances in the understanding of the biochemistry, physiology and therapeutics of nitrate, nitrite and NO were discussed during a recent 2-day meeting at the Nobel Forum, Karolinska Institutet in Stockholm.
Abstract: Inorganic nitrate and nitrite from endogenous or dietary sources are metabolized in vivo to nitric oxide (NO) and other bioactive nitrogen oxides. The nitrate-nitrite-NO pathway is emerging as an important mediator of blood flow regulation, cell signaling, energetics and tissue responses to hypoxia. The latest advances in our understanding of the biochemistry, physiology and therapeutics of nitrate, nitrite and NO were discussed during a recent 2-day meeting at the Nobel Forum, Karolinska Institutet in Stockholm.
536 citations
Utrecht University1, University of Warwick2, Medical College of Wisconsin3, Wake Forest University4, Ohio State University5, Karolinska Institutet6, Research Triangle Park7, University of Veterinary Medicine Vienna8, Institut national de la recherche agronomique9, National Institutes of Health10, Semenov Institute of Chemical Physics11, University of Pittsburgh12
TL;DR: The mechanisms and properties of these various pathways and the role played by the local concentration of free oxygen in the affected tissue are discussed and additional direct signaling events not involving free nitric oxide are proposed.
Abstract: In this review we consider the effects of endogenous and pharmacological levels of nitrite under conditions of hypoxia. In humans, the nitrite anion has long been considered as metastable intermediate in the oxidation of nitric oxide radicals to the stable metabolite nitrate. This oxidation cascade was thought to be irreversible under physiological conditions. However, a growing body of experimental observations attests that the presence of endogenous nitrite regulates a number of signaling events along the physiological and pathophysiological oxygen gradient. Hypoxic signaling events include vasodilation, modulation of mitochondrial respiration, and cytoprotection following ischemic insult. These phenomena are attributed to the reduction of nitrite anions to nitric oxide if local oxygen levels in tissues decrease. Recent research identified a growing list of enzymatic and nonenzymatic pathways for this endogenous reduction of nitrite. Additional direct signaling events not involving free nitric oxide are proposed. We here discuss the mechanisms and properties of these various pathways and the role played by the local concentration of free oxygen in the affected tissue.
388 citations
TL;DR: The development of a novel colorimetric nitrite and nitrate ion assay based upon gold nanoparticle probes functionalized with Griess reaction reagents that can be triggered at the EPA limit for this ion in drinking water.
Abstract: We report the development of a novel colorimetric nitrite and nitrate ion assay based upon gold nanoparticle probes functionalized with Griess reaction reagents. This assay takes advantage of the distance-dependent plasmonic properties of the gold nanoparticles and the ability of nitrite ion to facilitate the cross coupling of novel nanoparticle probes modified with aniline and naphthalene moieties. The assay works on the concept of a kinetic end point and can be triggered at the EPA limit for this ion in drinking water (highlighted in red, μM). This rapid and simple assay could be useful for on-site water quality monitoring.
313 citations
TL;DR: Sulfamic acid addition is applied to analyses of the coupled N and O isotopes of nitrate and nitrite in waters of the Mexican Margin, to illustrate its efficacy and utility when employed either in the field upon sample collection or in the lab after months of frozen sample storage.
Abstract: In environmental water samples that contain both nitrate (NO) and nitrite (NO), isotopic analysis of nitrate alone by all currently available methods requires pretreatment to remove nitrite. Sulfamic acid addition, used previously for this purpose (Wu JP, Calvert SE, Wong CS. Deep-SeaResearchPartI–OceanographicResearchPapers 1997; 44: 287), is shown here to be compatible with the denitrifier method for both N and O isotope analysis of nitrate. Sulfamic acid at a pH of ∼1.7 reduces nitrite to N2. Samples are then neutralized with base prior to isotope analysis, to alleviate the buffering demands of the bacterial media and as a precaution to prevent modification of nitrate during storage with the residual sulfamic acid at low pH. Under appropriate reaction conditions, nitrite is completely removed within minutes. Sulfamic acid treatment does not compromise the completeness of the conversion of nitrate into N2O or the precision and accuracy of N and O isotope measurements by the denitrifier method. Nitrite concentrations upwards of 7 times the ambient nitrate can be removed without affecting the isotope composition of nitrate. The method is applied to analyses of the coupled N and O isotopes of nitrate and nitrite in waters of the Mexican Margin, to illustrate its efficacy and utility when employed either in the field upon sample collection or in the lab after months of frozen sample storage. Copyright © 2009 John Wiley & Sons, Ltd.
275 citations
TL;DR: In this article, the nitrogen isotope effect was measured for microbial nitrite oxidation to nitrate, and it was shown that the fractionation is most likely inverse at the enzyme level.
231 citations
TL;DR: Results suggest an anti-inflammatory effect of GYY4137, a slow-releasing hydrogen sulfide (H(2)S) donor, which inhibited LPS-induced TNF-alpha production in rat blood and reduced the L PS-evoked rise in NF-kappaB activation, inducible nitric oxide synthase/cyclooxygenase-2 expression, and generation of PGE and nitrate/nitrite in RAW 2647 macrophages.
231 citations
TL;DR: In this article, an uncompetitive model fit the experimental data well when the reactions were under FA inhibition, whereas a noncompetitive model fit well under FNA inhibition, and a kinetic model for simultaneous inhibition by free ammonia (FA) and free nitrous acid (FNA) was derived.
219 citations
TL;DR: Comparing the performance of partial nitrification via nitrite and microbial community structure were investigated and compared in two sequencing batch reactors with different dissolved oxygen (DO) levels indicated that selecting properly DO level and adopting process control method is not only of benefit to the achievement of novel biological nitrogen removal technology, but also favorable to sludge population optimization.
210 citations
TL;DR: The results suggest that oral symbiotic bacteria modulate gastrointestinal and cardiovascular function via bioactivation of salivary nitrate via bioactivity of dietary nitrate through excessive use of antiseptic mouthwashes.
210 citations
TL;DR: It is shown that CA readily reacts with nitrite to generate NO, particularly at low pH, and that the NO produced in the reaction induces vasodilation in aortic rings, and a novel nitrous anhydrase enzymatic activity of CA would function to link the in vivo main end products of energy metabolism (CO2/H+) to the generation of vasoactive NO.
Abstract: 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 the reaction induces vasodilation in aortic rings. This reaction occurs under normoxic and hypoxic conditions and in various tissues at physiological levels of CA and nitrite. Furthermore, two specific inhibitors of the CO2 hydration, dorzolamide and acetazolamide, increase the CA-catalyzed production of vasoactive NO from nitrite. This enhancing effect may explain the known vasodilating effects of these drugs and indicates that CO2 and nitrite bind differently to the enzyme active site. Kinetic analyses show a higher reaction rate at high pH, suggesting that anionic nitrite participates more effectively 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 blood flow and metabolic activity in tissues, as occurring for instance in active areas of the brain.
205 citations
TL;DR: It is demonstrated that the nitrite pathway could be repeatedly and reliably achieved, with over 95% of the oxidized nitrogen compounds at the end of the aerobic zone being nitrite.
TL;DR: A mechanism of photodecay of monochloramine is proposed and nitrate formation was favored at low pH, while nitrite formation wasavored at high pH, and the effects of pH on formation of N2O and NH4+ were less clear.
Abstract: The ultraviolet (UV) photolysis of monochloramine (NH2Cl), dichloramine (NHCl2), and trichloramine (NCl3) in aqueous solution was investigated at wavelengths of 222, 254, and 282 nm. All three chloramines can be degraded by UV irradiation, and the quantum yields for these processes are wavelength-dependent. Stable photoproducts include nitrite, nitrate, nitrous oxide, and ammonium. Solution pH was observed to have little effect on the rate of photodecay; however, the product distribution showed strong pH dependence. Nitrate formation was favored at low pH, while nitrite formation was favored at high pH. The effects of pH on formation of N2O and NH4+ were less clear. On the basis of the results, a mechanism of photodecay of monochloramine is proposed.
TL;DR: This Account reviews three novel metal- and nitrite-catalyzed reaction pathways in the context of historical studies of nitrite and hemoglobin chemistry and attempts to place them in the biological framework of hypoxic signaling.
Abstract: Because of their critical biological roles, hemoglobin and myoglobin are among the most extensively studied proteins in human history, while nitrite tops the list of most-studied small molecules. And although the reactions between them have been examined for more than 140 years, a series of unusual and critical allosterically modulated reactions have only recently been characterized. In this Account, we review three novel metal- and nitrite-catalyzed reaction pathways in the context of historical studies of nitrite and hemoglobin chemistry and attempt to place them in the biological framework of hypoxic signaling. Haldane first described the reaction between nitrite and deoxymyoglobin, forming iron-nitrosylated myoglobin, in his analysis of the meat-curing process more than a century ago. The reaction of nitrous acid with deoxyhemoglobin to form nitric oxide (NO) and methemoglobin was more fully characterized by Brooks in 1937, while the mechanism and unusual behavior of this reaction were further detaile...
TL;DR: Novel anti-inflammatory properties of nitrite are revealed and the use of nitrites as a new natural therapy for microvascular inflammation and endothelial dysfunction associated with hypercholesterolemia are implicate.
Abstract: The nitrite anion is an endogenous product of mammalian nitric oxide (NO) metabolism, a key intermediate in the nitrogen cycle in plants, and a constituent of many foods. Research over the past 6 years has revealed surprising biological and cytoprotective activity of this anion. Hypercholesterolemia causes a proinflammatory phenotype in the microcirculation. This phenotype appears to result from a decline in NO bioavailability that results from a reduction in NO biosynthesis, inactivation of NO by superoxide, or both. Since nitrite has been shown to be potently cytoprotective and restore NO biochemical homeostasis, we investigated if supplemental nitrite could attenuate microvascular inflammation caused by a high cholesterol diet. C57Bl/6J mice were fed either a normal diet or a high cholesterol diet for 3 wk to induce microvascular inflammation. Mice on the high cholesterol diet received either nitrite-free drinking water or supplemental nitrite at 33 or 99 mg/l ad libitum in their drinking water. The results from this investigation reveal that mice fed a cholesterol-enriched diet exhibited significantly elevated leukocyte adhesion to and emigration through the venular endothelium as well as impaired endothelium-dependent relaxation in arterioles. Administration of nitrite in the drinking water inhibited the leukocyte adhesion and emigration and prevented the arteriolar dysfunction. This was associated with sparing of reduced tetrahydrobiopterin and decreased levels of C-reactive protein. These data reveal novel anti-inflammatory properties of nitrite and implicate the use of nitrite as a new natural therapy for microvascular inflammation and endothelial dysfunction associated with hypercholesterolemia.
TL;DR: This method was successfully applied to various water samples--river water, pond water, rain water, commercial mineral water, and tap water--with only filtration and dilution steps.
TL;DR: In this article, a simple and fast analytical method for determining nitrate and nitrite contents in vegetables and meat, using reversed-phase HPLC-UV, was described, which is applicable for both leafy vegetable and meat samples.
TL;DR: The results indicate that physiological responses, and perhaps environmental adaptations, to N compounds are organism specific for methanotrophs.
Abstract: Ecological studies have indicated that relative abundances of Gammaproteobacteria methanotrophs (Gamma-MOB) vs. Alphaproteobacteria methanotrophs (Alpha-MOB) in nitrogen (N) impacted soils are dictated in part by their abilities to tolerate inhibitory effects of ammonium and nitrite. In particular, ammonia is a cometabolic substrate and competitive inhibitor of methane monooxygenase. The rates of ammonia and hydroxylamine oxidation and inhibition of methane-oxidizing activity by ammonium and nitrite were compared among two Gamma-MOB and two Alpha-MOB to determine whether methanotrophs of the same class shared similar physiological profiles. Each isolate exhibited unique Km(app) for ammonia and Vmax for nitrite production with or without reductant (methane or sodium formate). The rates of nitrite production from hydroxylamine followed similar trends to rates of ammonia oxidation, indicating that hydroxylamine-oxidizing enzymes were central participants in the ammonia-oxidizing pathway. Methylomonas methanica was incapable of either ammonia or hydroxylamine oxidation. A broad range of sensitivities to ammonium and nitrite inhibition were measured with little consistency between isolates of the same class. The results indicate that physiological responses, and perhaps environmental adaptations, to N compounds are organism specific for methanotrophs.
TL;DR: The proposed method was successfully applied in the detection of nitrite in water samples and sausage samples, and the results were consistent with those obtained by ion chromatography and UV-visible spectrophotometric methods.
TL;DR: The degradation assays suggested that the strain NJUST16 could utilize picric acid as the sole source of carbon, nitrogen and energy.
TL;DR: A metal-free catalytic system consisting of 2,2,6,6-tetramethylpiperidine N-oxyl (TEMPO) and tert-butyl nitrite has been developed to activate molecular oxygen for the aerobic oxidation of alcohols as discussed by the authors.
Abstract: A metal-free catalytic system consisting of 2,2,6,6-tetramethylpiperidine N-oxyl (TEMPO) and tert-butyl nitrite has been developed to activate molecular oxygen for the aerobic oxidation of alcohols A variety of active and non-active alcohols were oxidized to their corresponding carbonyl compounds in high selectivity and yields
TL;DR: N(2)O production during nitrogen removal via nitrite decreased about 50% by applying the step-feed SBR, due to the effective control of nitrite and ammonia, the precursors of N(2]O production.
Abstract: Nitrite has been commonly recognized as an important factor causing N2O production, which weakened the advantages of nitrogen removal via nitrite. To reduce and control N2O production from wastewater treatment plants, both long-term and batch tests were carried out to investigate main sources and pathways of N2O production during nitrogen removal via nitrite from real domestic wastewater. The obtained results showed that N2O production during nitrogen removal via nitrite was 1.5 times as much as that during nitrogen removal via nitrate. It was further demonstrated that ammonia oxidization were main source of N2O production during nitrogen removal from domestic wastewater; whereas, almost no N2O was produced during nitrite oxidization and anoxic denitrification. N2O production during nitrogen removal via nitrite decreased about 50% by applying the step-feed SBR, due to the effective control of nitrite and ammonia, the precursors of N2O production. Therefore, the step-feed system is recommended as an effect...
TL;DR: A glassy carbon (GC) electrode modified with alternated layers of iron(III) tetra-(N-methyl-4-pyridyl)-porphyrin (FeT4MPyP) and copper tetrasulfonated phthalocyanine (CuTSPc) was employed for nitrite determination by differential pulse voltammetry (DPV).
TL;DR: The results showed a stable operation of the partial nitrification system during more than 100 days and NOB washout was corroborated with fluorescence in-situ hybridization (FISH) analysis.
TL;DR: From kinetic data, it was determined that during ischemia hepatic, pulmonary, or myocardial AO and nitrite levels were sufficient to result in NO generation comparable to or exceeding maximal production by constitutive NO synthases, suggesting AO-catalyzed nitrite reduction can be an important source of NO generation.
TL;DR: Both the skin and the dermal vasculature contain biologically significant stores of NO, particularly nitrite, which can be directly mobilized by UVA irradiation, and the level of circulating NO-related products probably determines skin-bound stores.
TL;DR: R/NIR light can decay nitrosyl hemes and release NO, and that this released NO may enhance the cardioprotective effects of nitrite, and the photodissociation to NO and its synergistic effect with sodium nitrite may represent a noninvasive and site specific means for increasing NO bioavailability.
TL;DR: Results show, for the first time, a protective effect for GC because of higher intake of cinnamic acids, secoisolariciresinol and coumestrol, and suggest that these polyphenols reduce GC risk through inhibition of endogenous nitrosation.
Abstract: N-nitroso compounds (NOC) are potent animal carcinogens and potential human carcinogens. The primary source of exposure for most individuals may be endogenous formation, a process that can be inhibited by dietary polyphenols. To estimate the risk of gastric cancer (GC) in relation to the individual and combined consumption of polyphenols and NOC precursors (nitrate and nitrite), a population-based case-control study was carried out in Mexico City from 2004 to 2005 including 257 histologically confirmed GC cases and 478 controls. Intake of polyphenols, nitrate and nitrite were estimated using a food frequency questionnaire. High intakes of cinnamic acids, secoisolariciresinol and coumestrol were associated with an approximately 50% reduction in GC risk. A high intake of total nitrite as well as nitrate and nitrite from animal sources doubled the GC risk. Odds ratios around 2-fold were observed among individuals with both low intake of cinnamic acids, secoisolariciresinol or coumestrol and high intake of animal-derived nitrate or nitrite, compared to high intake of the polyphenols and low animal nitrate or nitrite intake, respectively. Results were similar for both the intestinal and diffuse types of GC. Our results show, for the first time, a protective effect for GC because of higher intake of cinnamic acids, secoisolariciresinol and coumestrol, and suggest that these polyphenols reduce GC risk through inhibition of endogenous nitrosation. The main sources of these polyphenols were pears, mangos and beans for cinnamic acids; beans, carrots and squash for secoisolariciresinol and legumes for coumestrol.
TL;DR: The findings demonstrated that the population structure of nitrite-oxidizing bacteria in activated sludge is more complex than previously thought and responds strongly to long-term temperature changes.
Abstract: Activated sludge from the municipal waste water treatment plant in Hamburg was seeded with mineral nitrite medium and incubated at 10°C, 17°C and 28°C. Dominant lithoautotrophic nitrite-oxidizing bacteria have been identified by electron microscopy, denaturing and temperature gradient gel electrophoresis and PCR with genus-specific primer pairs. The results have revealed the existence of three different genera of nitrite-oxidizing bacteria, namely Nitrospira, Nitrobacter and a novel cold-adapted nitrite oxidizer. As shown by electron microscopy members of the novel genus coexisted in activated sludge together with Nitrospira. A temperature-dependent shift in the population structure was demonstrated by cultivation-based approaches. The novel nitrite oxidizer was enriched at temperatures of 10°C and 17°C. Representatives of Nitrospira were able to grow in a broad temperature range between 10°C and 28°C and members of Nitrobacter were enriched during incubations at 17°C and 28°C. By subsequent 16S rDNA sequencing, the cold-adapted nitrite oxidizer was shown to be closely related to the betaproteobacterium 'Candidatus Nitrotoga arctica'. These findings demonstrated that the population structure of nitrite-oxidizing bacteria in activated sludge is more complex than previously thought and responds strongly to long-term temperature changes.
TL;DR: Tobacco cell suspensions emitted NO when hydroxylamine or salicylhydroxamate, a frequently used AOX inhibitor, was added and the addition of superoxide dismutase (SOD) to cell suspensions stimulated NO formation from Hydroxylamines, and SOD alone (without cells) also catalysed the production of NO from HA or SHAM.
Abstract: Plants are known to produce NO via the reduction of nitrite. Oxidative NO production in plants has been considered only with respect to a nitric oxide synthase (NOS). Here it is shown that tobacco cell suspensions emitted NO when hydroxylamine (HA) or salicylhydroxamate (SHAM), a frequently used AOX inhibitor, was added. N(G)-hydroxy-L-arginine, a putative intermediate in the NOS-reaction, gave no NO emission. Only a minor fraction (< or = 1%) of the added HA or SHAM was emitted as NO. Production of NO was decreased by anoxia or by the addition of catalase, but was increased by conditions inducing reactive oxygen (ROS) or by the addition of hydrogen peroxide. Cell-free enzyme solutions generating superoxide or hydrogen peroxide also led to the formation of NO from HA or (with lower rates) from SHAM, and nitrite was also an oxidation product. Unexpectedly, the addition of superoxide dismutase (SOD) to cell suspensions stimulated NO formation from hydroxylamines, and SOD alone (without cells) also catalysed the production of NO from HA or SHAM. NO production by SOD plus HA was higher in nitrogen than in air, but from SOD plus SHAM it was lower in nitrogen. Thus, SOD-catalysed NO formation from SHAM and from HA may involve different mechanisms. While our data open a new possibility for oxidative NO formation in plants, the existence and role of these reactions under physiological conditions is not yet clear.
TL;DR: 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.