nitrogen-dioxide and nitrogen-trioxide

A reaction of arachidonic acid with the nitrogen dioxide radical (*NO2) or its precursors (peroxynitrite, nitrous acid, nitrogen trioxide) generates a group of nitro lipids named nitroeicosanoids. A distinct feature of this reaction is abundant formation of four trans isomers of arachidonic acid (TAA) via reversible addition of the NO2 radical to the arachidonic acid cis double bonds. This cis-trans isomerization is biologically relevant because many pathologies that involve NO formation such as inflammation, hyperoxia, hypercapnia or exposure to cigarette smoke increase the TAA levels in cells, tissues and in the systemic circulation. Inflammatory conditions have been known to stimulate formation of a variety of oxidized lipids from unsaturated fatty acid precursors via lipid peroxidation mechanisms; however, nitration-dependent cis-trans-isomerization of arachidonic acid is a characteristic process for *NO2. TAA are likely to function as specific and selective biomarkers of the pathologic conditions that define nitro-oxidative stress. Diet independent biosynthesis of trans fatty acids as a result of disease is our new observation. In the past, experimental feeding and clinical studies have supported the concerns that dietary trans fatty acids are cardiovascular risk factors, however, clinical consequences of the endogenous formation of trans fatty acids are not known but potentially important given available studies on TAA. This review aims to summarize the emerging role of TAA as a unique group of biomarkers that target microcirculation and other systems. A biological mechanism that generates endogenous trans fatty acids poses new challenges for pharmacologic intervention and we suggest approaches that may limit TAA effects.

Topics: Animals; Arachidonic Acids; Humans; Models, Biological; Molecular Structure; Nitrogen Dioxide; Nitrogen Oxides; Oxidative Stress; Signal Transduction; Stereoisomerism; Trans Fatty Acids

Marfan syndrome (MS) is an autosomal dominant disorder of connective tissue that is caused by mutations in the fibrillin-1 (FBN-1) gene that cause degeneration of the artery. It is accompanied by endothelial dysfunction. The potential transient receptor of the vanilloid subfamily 1 (TRPV1) ion channel plays an important role in endothelial vascular functioning. Here we determine the association of the presence TRPV1 in aortic aneurysm with dilation and dissection of the artery in MS patients. Histological sections of aortic aneurysm tissue obtained by the surgical procedure of Bentall and De Bono or David, were processed by immunohistochemistry with antibodies against ICAM, VCAM, iNOS, eNOS, TRPV1 and TNF-α and the immunolabelling area was determined. We also measured the NO₃⁻/NO₂⁻ ratio in the aortic tissue. C-reactive protein and HDL in plasma were quantified. A significant increase in iNOS, TRPV1, VCAM (p≤0.05), NO₃⁻/NO₂⁻ ratio (p=0.002) and a significant decrease in eNOS (p=0.04) and HDL in plasma (p=0.02) in the MS vs. the C group were found. Conclusion: TRPV1 is over-expressed in aortic tissue from MS patients and can be associated with increases in iNOS, VCAM and a decrease in eNOS. These changes might contribute to the progression and rupture of the thoracic aneurysm.

Topics: Adult; Aneurysm; Aortic Aneurysm, Thoracic; C-Reactive Protein; Disease Progression; Female; Fibrillin-1; Gene Expression Regulation; Humans; Immunohistochemistry; Inflammation; Intercellular Adhesion Molecule-1; Lipoproteins, HDL; Male; Marfan Syndrome; Middle Aged; Nitric Oxide Synthase Type III; Nitrogen Dioxide; Nitrogen Oxides; Phenotype; TRPV Cation Channels; Vascular Cell Adhesion Molecule-1

Cold Atmospheric Plasma (CAP) is an ionized gas with a near room temperature. CAP is a controllable source for reactive species, neutral particles, electromagnetic field and UV radiation. CAP showed the promising application in cancer treatment through the demonstration in vitro and in vivo. In this study, we first demonstrate the existence of an activation state on the CAP-treated cancer cells, which drastically decreases the threshold of cell vulnerability to the cytotoxicity of the CAP-originated reactive species such as H

Topics: Adenocarcinoma; Cell Survival; Cold Temperature; Humans; Hydrogen Peroxide; Nitrogen Dioxide; Nitrogen Oxides; Pancreatic Neoplasms; Plasma Gases; Tumor Cells, Cultured

Variable climatic conditions strongly influence phytoplankton dynamics in estuaries globally. Our study area is Chesapeake Bay, a highly productive ecosystem providing natural resources, transportation, and recreation for nearly 16 million people inhabiting a 165,000-km(2) watershed. Since World War II, nutrient over-enrichment has led to multiple ecosystem impairments caused by increased phytoplankton biomass as chlorophyll-a (chl-a). Doubled nitrogen (N) loadings from 1945-1980 led to increased chl-a, reduced water clarity, and low dissolved oxygen (DO), while decreased N loadings from 1981-2012 suggest modest improvement. The recent 30+ years are characterized by high inter-annual variability of chl-a, coinciding with irregular dry and wet periods, complicating the detection of long-term trends. Here, we synthesize time-series data for historical and recent N loadings (TN, NO2 + NO3), chl-a, floral composition, and net primary productivity (NPP) to distinguish secular changes caused by nutrient over-enrichment from spatio-temporal variability imposed by climatic conditions. Wet years showed higher chl-a, higher diatom abundance, and increased NPP, while dry years showed lower chl-a, lower diatom abundance, and decreased NPP. Our findings support a conceptual model wherein variable climatic conditions dominate recent phytoplankton dynamics against a backdrop of nutrient over-enrichment, emphasizing the need to separate these effects to gauge progress toward improving water quality in estuaries.

Topics: Bays; Biomass; Chlorophyll; Chlorophyll A; Climate; Eutrophication; Maryland; Nitrogen Dioxide; Nitrogen Oxides; Phytoplankton; Seawater; Water Pollution, Chemical; Water Quality

Mitigation of nitrous oxide (N2 O) emission from swine wastewater treatment was demonstrated in an aerobic bioreactor packed with carbon fibers (CF reactor). The CF reactor had a demonstrated advantage in mitigating N2 O emission and avoiding NOx (NO3  + NO2 ) accumulation. The N2 O emission factor was 0.0003 g N2 O-N/gTN-load in the CF bioreactor compared to 0.03 gN2 O-N/gTN-load in an activated sludge reactor (AS reactor). N2 O and CH4 emissions from the CF reactor were 42 g-CO2 eq/m(3) /day, while those from the AS reactor were 725 g-CO2 eq/m(3) /day. The dissolved inorganic nitrogen (DIN) in the CF reactor removed an average of 156 mg/L of the NH4 -N, and accumulated an average of 14 mg/L of the NO3 -N. In contrast, the DIN in the AS reactor removed an average 144 mg/L of the NH4 -N and accumulated an average 183 mg/L of the NO3 -N. NO2 -N was almost undetectable in both reactors.

Topics: Aerobiosis; Ammonia; Animals; Bioreactors; Carbon; Carbon Fiber; Denitrification; Gases; Molecular Sequence Data; Nitrogen Dioxide; Nitrogen Oxides; Nitrous Oxide; Sewage; Swine; Wastewater; Water Purification

We have previously reported that impaired skin barrier function was induced by small intestinal injury in mice. Therefore, we postulated that other intestinal diseases might also influence skin barrier function. In this study, we evaluated the skin barrier function of hairless mice with colon carcinoma that was induced by azoxymethane (AOM) and dextran sodium sulfate (DSS). In mice treated with these drugs, we observed elevated transepidermal water loss and reduced skin hydration levels, compared to those in the control mice. In addition, plasma nitrogen di/trioxide (NO2(-)/NO3(-)) levels were significantly elevated, and expression of type I collagen was significantly reduced in the treated mice, compared to those in control. These results suggest that impaired skin barrier function occurs in mice when colon carcinoma is present.

Topics: Animals; Azoxymethane; Cell Membrane Permeability; Collagen Type I; Colon; Colonic Neoplasms; Dextran Sulfate; Male; Mice, Hairless; Nitrogen Dioxide; Nitrogen Oxides; Skin; Water

Blockade of the T-type calcium channel (TCC), which is expressed in the renal efferent arterioles of the juxtamedullary nephron and vasa recta, has been shown to protect against renal injury. Studies were designed to determine the effects of a specific TCC blocker, R(-) efonidipine [R(-)EFO], on the regulation of renal circulation.. Renal medullary blood flux (MBF) and cortical blood flux (CBF) were simultaneously monitored using laser-Doppler flowmetry in Sprague-Dawley rats. Responses were also determined in rats with angiotensin II (AngII) induced renal ischemia. Intravenous (i.v.) or renal interstitial (r.i.) infusion of R(-)EFO (0.25 mg/h, i.v. or r.i.) significantly increased MBF by 24.0 ± 7.0 and 21.0 ± 4.4%, respectively, but without changing CBF or mean arterial pressure. The nitric oxide (NO) synthase inhibitor NG-nitro-L-argininemethylester (L-NAME, 1 μg/kg per min, i.v. or r.i.) significantly attenuated R(-)EFO-induced increase in MBF. R(-)EFO inhibited the AngII-mediated (50 ng/kg per min, i.v.) reduction of MBF (28.4 ± 1.7%), which was associated with increased urinary NO(2) + NO(3) excretion and decreased urinary hydrogen peroxide (H(2)O(2)) excretion. Intracellular H(2)O(2) fluorescence (real-time fluorescence imaging) in the epithelial cells of isolated medullary thick ascending limb (mTAL) significantly increased following AngII stimulation (1 μmol/L, 235 ± 52 units), which was significantly inhibited by pre and coincubation with R(-)EFO. R(-)EFO stimulation also increased the intracellular NO concentration in the epithelial cells of mTAL (220 ± 62 units).. These results suggest that TCC blockade with R(-)EFO selectively increases MBF, an effect that appears to be mediated by changes in renal NO and oxidative stress balance, which may protect against ischemic renal injury in the renal medullary region.

Topics: Angiotensin II; Animals; Blood Flow Velocity; Calcium Channel Blockers; Calcium Channels, T-Type; Dihydropyridines; Disease Models, Animal; Drug Antagonism; Infusions, Intravenous; Ischemia; Kidney Medulla; Laser-Doppler Flowmetry; NG-Nitroarginine Methyl Ester; Nitrogen Dioxide; Nitrogen Oxides; Nitrophenols; Organophosphorus Compounds; Rats; Rats, Sprague-Dawley; Renal Circulation; Vasoconstrictor Agents

Recombinant human erythropoietin (rHuEPO), used clinically for renal anemia, reportedly exhibits pleiotropic properties in various tissues. To test whether it ameliorates vascular injury, rHuEPO (75U/kg) was administered subcutaneously every 3days for 10days to 5/6 nephrectomized hypertensive rats (5/6Nx) treated with 1% NaCl. rHuEPO had no effect on increased systolic blood pressure or decreased hematocrit values, but normalized levels of proteinuria and creatinine clearance. Vasodilation in response to acetylcholine in the aortic ring was impaired in the 5/6Nx, and improved by treatment with rHuEPO. Immunohistochemical analysis revealed that the infiltration of adventitial areas by macrophages and expression of osteopontin were enhanced in the 5/6Nx aorta and the overexpression was suppressed by rHuEPO. rHuEPO also attenuated medial hyperplasia. Akt signaling was activated by the increased expression of phosphorylated Akt and GSK-3β in aorta from rHuEPO-treated 5/6Nx. rHuEPO restored plasma NOx (NO(2)(-)+NO(3)(-)) levels and endothelial nitric oxide synthase (eNOS) content in the 5/6Nx aorta. Treatment with an eNOS substrate, l-arginine, which caused a similar increase in plasma NOx levels as the rHuEPO treatment, resulted in a normalization of endothelial dysfunction and vascular inflammation. These results suggest that a low dose of rHuEPO exerted vasoprotective effects in rats with hypertensive renal failure.

Topics: Acetylcholine; Animals; Aorta; Aorta, Thoracic; Blood Pressure; Body Weight; Connective Tissue; Dose-Response Relationship, Drug; Endothelium, Vascular; Erythropoietin; Gene Expression Regulation, Enzymologic; Hematocrit; Hematopoiesis; Humans; Hypertension; Macrophages; Male; Nephrectomy; Nitric Oxide; Nitric Oxide Synthase Type III; Nitrogen Dioxide; Nitrogen Oxides; Nitroprusside; Osteopontin; Phosphoproteins; Rats; Rats, Wistar; Recombinant Proteins

Alkylnaphthalenes are minor constituents of vehicle fuels and are emitted into the atmosphere in vehicle exhaust and other sources of incomplete combustion. In the lower atmosphere, alkylnaphthalenes react with OH radicals during daylight hours and with NO3 radicals during evening and nighttime, and both radical-initiated reactions have been postulated to explain ambient alkylnitronaphthalene profiles. To obtain insight into the NO3 radical reaction mechanism, we have investigated the formation of potentially genotoxic ethyl- and dimethyl-nitronaphthalenes and quinones, as well as aromatic carbonyls, from the NO3 radical-initiated reactions of ethylnaphthalenes (ENs) and dimethylnaphthalenes (DMNs) over the NO2 concentration range approximately 0.2-2 ppmV. Our results for the formation of alkylnitronaphthalenes are consistent with gas-phase NO3 radical-initiated reactions being a source of alkylnitronaphthalenes in ambient air, and it appears that quinone formation from the gas-phase nighttime reactions of NO3 radicals with 2,6- and 2,7-DMN may be important in the atmosphere and warrants further investigation.

Topics: Gas Chromatography-Mass Spectrometry; Naphthalenes; Nitrogen Dioxide; Nitrogen Oxides

Supercontinuum radiation sources are attractive for spectroscopic applications owing to their broad wavelength coverage, which enables spectral signatures of multiple species to be detected simultaneously. Here we report the first use of a supercontinuum radiation source for broadband trace gas detection using a cavity enhanced absorption technique. Spectra were recorded at bandwidths of up to 100 nm, encompassing multiple absorption bands of H(2)O, O(2) and O(2)-O(2). The same instrument was also used to make quantitative measurements of NO(2) and NO(3). For NO(3) a detection limit of 3 parts-per-trillion in 2 s was achieved, which corresponds to an effective 3sigma sensitivity of 2.4 x 10(-9) cm(-1)Hz(-1/2). Our results demonstrate that a conceptually simple and robust instrument is capable of highly sensitive broadband absorption measurements.

Topics: Air Pollutants; Atmosphere; Environmental Monitoring; Equipment Design; Gases; Nitrogen Dioxide; Nitrogen Oxides; Oxygen; Physics; Radiation; Spectrophotometry; Spectrophotometry, Infrared; Water

Coffee contains antioxidants like chlorogenic acid and its isomers. In this report, effects of coffee on the nitrite-induced N2O3 formation were studied using whole saliva and bacterial fraction prepared from the saliva. The formation of N2O3 was measured by fluorescence increase due to the transformation of 4,5-diaminofluorescein to triazolfluorescein. Coffee inhibited the nitrite-induced fluorescence increase, and 50% inhibition was observed at several microg of coffee/mL in bacterial fraction of saliva as well as whole saliva. During the inhibition of the fluorescence increase, concentration of chlorogenic acid and its isomers decreased. It is discussed that the reduction of NO2 by chlorogenic acid and its isomers contributed to the coffee-dependent inhibition of the fluorescence increase as N2O3 is formed from NO and NO2. When coffee was added to whole saliva, chlorogenic acid and its isomers bound to cells in the saliva. The rate of the fluorescence increase in bacterial fraction, which was prepared at defined periods after the ingestion of coffee, was increased to the rate before the ingestion of coffee with a half-time of about 1 h. This result suggests that chlorogenic acid and its isomers remained in the oral cavity for a few hours after ingestion of coffee. The significance of coffee drinking and rinsing of the mouth with coffee for the health of the oral cavity is proposed.

Topics: Bacteria; Chlorogenic Acid; Coffee; Free Radical Scavengers; Humans; Nitrogen Dioxide; Nitrogen Oxides; Oxidation-Reduction; Saliva; Spectrometry, Fluorescence

The sequencing batch reactor (SBR) is a widely used process for biological removal of nutrients (nitrogen and phosphorus) from wastewater. It is based on the metabolism of specialised bacteria, which under alternate anaerobic/aerobic conditions uptake phosphorus and perform denitrification. Intermittent operation is normally operated on a fixed switching schedule with ample margin for possible inaccuracies, with the result that the process operation is highly inefficient. This paper proposes a switching strategy based on the indirect observation of process state through simple physico-chemical measurements and the use of an inferential engine to determine the most appropriate switching schedule. In this way the duration of each phase is limited to the time strictly necessary for the actual loading conditions. Experimental results show that the treatment cycle can be significantly shortened, with the results that more wastewater can be treated. The switching strategy is based on innovative data-processing techniques applied to simple process signals including pH, oxido-reduction potential (ORP) and dissolved oxygen (DO). They include wavelet filtering for signal denoising and fuzzy clustering for features extraction and decision-making. The formation of a knowledge-base and its adaptation during the operation are also discussed.

Topics: Aerobiosis; Ammonia; Anaerobiosis; Bioreactors; Cluster Analysis; Fuzzy Logic; Hydrogen-Ion Concentration; Nitrogen Dioxide; Nitrogen Oxides; Oxidation-Reduction; Oxygen; Pattern Recognition, Automated; Time Factors; Waste Disposal, Fluid

We demonstrate herein that nitric oxide (*NO) and nitrogen dioxide (*NO2) both react with the tyrosyl radical formed in sperm whale myoglobin (swMb) by reaction with hydrogen peroxide. The tyrosyl radical was detected by Western blotting using a novel anti-5,5-dimethyl-1-pyrroline N-oxide (DMPO) polyclonal antiserum that specifically recognizes protein radical-derived DMPO nitrone adducts. In the presence of DMPO, hydrogen peroxide reacts with swMb to form the DMPO tyrosyl radical as is known from both electron spin resonance and immuno-spin trapping investigations. Both *NO and NO2- significantly suppressed DMPO-Mb formation under the physiological oxygen tension of 30 mm Hg. If this inhibition of DMPO trapping of the tyrosyl radical is due, at least in part, to the reaction of the tyrosyl radical with *NO and *NO2, then nitrotyrosine should be formed. In line with this expectation, swMb treated with low concentrations of *NO or NO2- formed nitrotyrosine when hydrogen peroxide was added under 30 mm Hg oxygen tension as detected by Western blotting. The amount of nitrotyrosine generated with *NO was higher than with NO2-, implying that there are two different peroxynitrite-independent nitrotyrosine formation mechanisms and that *NO is not just a source of *NO2.

Topics: Aerobiosis; Animals; Blotting, Western; Cyclic N-Oxides; Free Radicals; Immune Sera; Immunochemistry; Myoglobin; Nitric Oxide; Nitrogen Dioxide; Nitrogen Oxides; Oxygen; Partial Pressure; Peroxynitrous Acid; Sperm Whale; Spin Trapping; Tyrosine

HIV-1 infected patients adherent to HAART and displaying stable increases in CD4 T-cell counts differ in their control of HIV replication and one might expect this to reflect depressed immune function. The importance of virological control in functional immune reconstitution was investigated in HIV-1 infected patients who maintained high or undetectable plasma HIV RNA levels over 2-4 years on HAART (discordant and complete responders, respectively). Immunocompetence and immune activation were assessed directly ex vivo and after a short period of culture, as HIV replication in cultures from viraemic patients may artificially depress responses. Expression of cytokine (interferon-gamma, interleukin-5) and chemokine receptor (CCR5, CRTH2) mRNA were determined and soluble CD30 and NO(2) (-)/NO(3) (-) were measured in sera. Unstimulated cells from all patients had low levels of IFNgamma mRNA relative to uninfected controls. Discordant responders had more IFNgamma, IL-5 and CCR5 mRNA in mitogen-stimulated PBMC than complete responders, where the difference could be attributed to CD8-T-cells. Serum NO(2) (-)/NO(3) (-) levels were significantly higher in all patients than controls, with no difference between complete and discordant responders. Serum CD30 levels were significantly higher in discordant responders. These data indicate a persistent immune deficit in immune reconstituted patients irrespective of HIV viral load and associate persistent viral replication with lymphocyte activation, probably involving CD8 T-cells.

Topics: Adult; Aged; Antiretroviral Therapy, Highly Active; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; HIV Infections; HIV-1; Humans; Interferon-gamma; Interleukin-5; Ki-1 Antigen; Leukocytes, Mononuclear; Middle Aged; Nitrogen Dioxide; Nitrogen Oxides; Receptors, CCR5; Receptors, Immunologic; Receptors, Prostaglandin; RNA, Messenger; RNA, Viral; T-Lymphocytes; Virus Replication

Inducible nitric oxide (NO) synthase (iNOS) is believed to contribute to the pathogenesis of endotoxin-induced uveitis (EIU). In the present study, we investigated the inhibitory effects of N(G)-nitro-L-arginine methyl ester (L-NAME), a non-selective NOS inhibitor, and S,S'-1,4-phenylene-bis(1,2-ethanediyl)bis-isothiourea (PBITU), a potent and selective iNOS inhibitor, on intraocular NO production in EIU rabbits using an in vivo intraocular microdialysis technique. The flare level in the anterior chamber increased from 1h after the injection of 100 micro g/kg lipopolysaccharide (LPS), and continued to increase for 24h. Aqueous humor protein concentrations were significantly increased at 24h after LPS-injection. These changes were significantly reduced by L-NAME (10mg/kg) and PBITU (1mg/kg), but not by D-NAME (10mg/kg). The increase in NO(2)(-) and NO(3)(-) levels in the dialysate induced by LPS was significantly inhibited by L-NAME (10mg/kg) and PBITU (1mg/kg), but not by D-NAME (10mg/kg). These results suggest that activation of iNOS may play a key role in the development of EIU, and selective inhibitors of iNOS may have therapeutic applications in the treatment of EIU.

Topics: Animals; Aqueous Humor; Disease Models, Animal; Enzyme Inhibitors; Lipopolysaccharides; Male; Microdialysis; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase; Nitrogen Dioxide; Nitrogen Oxides; Rabbits; Salmonella typhimurium; Thiourea; Uveitis

The atmospheric reaction NO2 + O3 --> NO3 + O2 (1) has been investigated theoretically by using the MP2, G2, G2Q, QCISD, QCISD(T), CCSD(T), CASSCF, and CASPT2 methods with various basis sets. The results show that the reaction pathway can be divided in two different parts at the MP2 level of theory. At this level, the mechanism proceeds along two transition states (TS1 and TS2) separated by an intermediate, designated as A. However, when the single-reference higher correlated QCISD methodology has been employed, the minimum A and the transition state TS2 are not found on the hypersurface of potential energy, which confirms a direct reaction mechanism. Single-reference high correlated and multiconfigurational methods consistently predict the barrier height of reaction (1) to be within the range 2.5-6.1 kcal mol(-1), in reasonable agreement with experimental data. The calculated reaction enthalpy is -24.6 kcal mol(-1) and the reaction rate calculated at the highest CASPT2 level, of k = 6.9 x 10(-18) cm(3) molecule(-1) s(-1). Both results can be regarded also as accurate predictions of the methodology employed in this article.

Topics: Atmosphere; Kinetics; Models, Theoretical; Nitrogen Dioxide; Nitrogen Oxides; Oxidation-Reduction; Oxygen; Ozone

Biochemical changes, total proteins, glycogen, aspartate and alanine (AAT and ALAT) amino transferases were studied with exposure of sublethal concentrations of NH3-N, NO2-N and NO3-N to the freshwater fish Catla catla (Hamilton), Labeo rohita (Hamilton) and Cirrhinus mrigala (Hamilton). Depletion in the food reserves and enzyme activity was observed in all the three fish species exposed to these toxicants. Hence, the concentrations of NH3, NO2 and NO3 in water need to be monitored in water quality in aquaculture practices.

Topics: Alanine Transaminase; Ammonia; Animals; Aquaculture; Aspartate Aminotransferases; Environmental Exposure; Fishes; Glycogen; Nitrogen; Nitrogen Dioxide; Nitrogen Oxides; Proteins

In patients with type 2 diabetes mellitus, we used nevibolol, a lipophilic high-selective beta 1-blocker. It has been found out that the drug, while augmenting the synthesis of nitrogen oxide, improves antioxidant properties. Therefore, it can be recommended for use in patients with type 2 diabetes mellitus concurrent with arterial hypertension to achieve normalization of arterial pressure and accomplish a correction of endothelial dysfunction.

Topics: Adrenergic beta-Antagonists; Benzopyrans; Diabetes Mellitus, Type 2; Endothelium, Vascular; Ethanolamines; Female; Humans; Male; Middle Aged; Nebivolol; Nitric Oxide; Nitric Oxide Synthase; Nitrogen Dioxide; Nitrogen Oxides

A close association has been reported for certain types of cancers influenced by aromatic amines and infection/inflammation. Reactive nitric oxygen species (RNOS), components of the inflammatory response, are bactericidal and tumoricidal, and contribute to the deleterious effects attributed to inflammation on normal tissues. This study assessed the possible transformation of the aromatic amine N-acetylbenzidine (ABZ) by RNOS. RNOS were generated by various conditions to react with ABZ, and samples were evaluated by HPLC. Conditions which generate nitrogen dioxide radical (NO(2)(-) + myeloperoxidase + H(2)O(2), ONOO(-), and NO(2)(-) + HOCl) produced primarily a single new product termed 3'-nitro-ABZ. The myeloperoxidase-catalyzed reaction with 0.3 mM NO(2)(-) was completely inhibited by 1 mM cyanide, and not effected by 100 mM chloride with or without 1 mM taurine. In contrast, conditions which generate N(2)O(3), such as spermine NONOate, did not produce 3'-nitro-ABZ, but rather two compounds termed 4'-OH-AABP and AABP. (1)H NMR and mass spectrometry identified 3'-nitro-ABZ as 3'-nitro-N-acetylbenzidine, 4'-OH-AABP as 4'-OH-4-acetylaminobiphenyl, and AABP as 4-acetylaminobiphenyl. Human polymorphonuclear neutrophils incubated with [(3)H]ABZ and stimulated with beta-phorbol 12-myristate 13-acetate produced 3'-nitro-ABZ in the presence of NO(2)(-) (0.1-1 mM). Neutrophil 3'-nitro-ABZ formation was verified by mass spectrometry and was consistent with myeloperoxidase oxidation of NO(2)(-). The results demonstrate that ABZ forms unique products in the presence of nitrosating and nitrating RNOS, which could influence the carcinogenic process and serve as biomarkers for these reactive species.

Topics: Benzidines; Cell Transformation, Neoplastic; Humans; Neutrophils; Nitrogen Dioxide; Nitrogen Oxides; Reactive Oxygen Species

Synchrotron-based high-resolution photoemission, X-ray absorption near-edge spectroscopy, and first-principles density functional (DF) slab calculations were used to study the interaction of NO(2) with a TiO(2)(110) single crystal and powders of titania. The main product of the adsorption of NO(2) on TiO(2)(110) is surface nitrate with a small amount of chemisorbed NO(2). A similar result is obtained after the reaction of NO(2) with polycrystalline powders of TiO(2) or other oxide powders. This trend, however, does not imply that the metal centers of the oxides are unreactive toward NO(2). An unexpected mechanism is seen for the formation of NO(3). Photoemission data and DF calculations indicate that the surface nitrate forms through the disproportionation of NO(2) on Ti sites (2NO(2,ads) --> NO(3,ads) + NO(gas)) rather than direct adsorption of NO(2) on O centers of titania. Complex interactions take place between NO(2) and O vacancies of TiO(2)(110). Electronic states associated with O vacancies play a predominant role in the bonding and surface chemistry of NO(2). The adsorbed NO(2), on its part, affects the thermochemical stability of O vacancies, facilitating their migration from the bulk to the surface of titania. The behavior of the NO(2)/titania system illustrates the importance of surface and subsurface defects when using an oxide for trapping or destroying NO(x)() species in the prevention of environmental pollution (DeNOx operations).

Topics: Environmental Pollutants; Nitrogen Dioxide; Nitrogen Oxides; Oxides; Oxygen; Surface Properties; Titanium

Topics: Free Radicals; Hydrogen-Ion Concentration; Hydroxyl Radical; Hydroxylation; Kinetics; Mannitol; Nitrates; Nitric Oxide; Nitrogen Dioxide; Nitrogen Oxides; Oxidants; Phenylalanine; Tyrosine