sodium-nitrite and sodium-nitrate

Nitric oxide (NO) has led a revolution in physiology and pharmacology research during the last two decades. This labile molecule plays an important role in many functions in the body regulating vasodilatation, blood flow, mitochondrial respiration and platelet function. Currently, it is known that NO synthesis occurs via at least two physiological pathways: NO synthase (NOS) dependent and NOS independent. In the former, L-arginine is the main precursor. It is widely recognized that this amino acid is oxidized to NO by the action of the NOS enzymes. Additionally, L-citrulline has been indicated to be a secondary NO donor in the NOS-dependent pathway, since it can be converted to L-arginine. Nitrate and nitrite are the main substrates to produce NO via the NOS-independent pathway. These anions can be reduced in vivo to NO and other bioactive nitrogen oxides. Other molecules, such as the dietary supplement glycine propionyl-L-carnitine (GPLC), have also been suggested to increase levels of NO, although the physiological mechanisms remain to be elucidated. The interest in all these molecules has increased in many fields of research. In relation with exercise physiology, it has been suggested that an increase in NO production may enhance oxygen and nutrient delivery to active muscles, thus improving tolerance to physical exercise and recovery mechanisms. Several studies using NO donors have assessed this hypothesis in a healthy, trained population. However, the conclusions from these studies showed several discrepancies. While some reported that dietary supplementation with NO donors induced benefits in exercise performance, others did not find any positive effect. In this regard, training status of the subjects seems to be an important factor linked to the ergogenic effect of NO supplementation. Studies involving untrained or moderately trained healthy subjects showed that NO donors could improve tolerance to aerobic and anaerobic exercise. However, when highly trained subjects were supplemented, no positive effect on performance was indicated. In addition, all this evidence is mainly based on a young male population. Further research in elderly and female subjects is needed to determine whether NO supplements can induce benefit in exercise capacity when the NO metabolism is impaired by age and/or estrogen status.

Topics: Arginine; Citrulline; Dietary Supplements; Endothelium-Dependent Relaxing Factors; Exercise Tolerance; Humans; Malates; Nitrates; Nitric Oxide; Nitric Oxide Synthase; Sodium Nitrite; Task Performance and Analysis

The main microbiological and physico-chemical parameters in dry-salted ham previously selected were determined along the elaboration process. All determinations were performed at 2 levels: surface and internal. All bacterial groups showed a similar behaviour, increasing along the first stages up to the third month of drying, then decreasing to numbers similar to the initial ones. Only the halotolerants maintained fairly high numbers during last stages. Some groups were almost absent at internal levels. The hazardous bacteria showed different behaviour: whereas the faecal streptococci were fairly abundant during the whole study, coliforms almost disappeared at the final stages. During the elaboration process at different stages of ripening they were analysed in order to know the moulds population at surface level. Aspergillus and Penicillium were the dominant genera. The latter, mainly represented by 10 species, dominated during the first stages of elaboration. Aspergillus was present throughout the whole making process. The glaucus group was clearly dominant at the final stages due to the low aw values together with the high NaCl percentages. Aspergillus halophilicus was the most abundant species identified (18%) and the most frequently isolated at the final stages.

Topics: Animals; Bacteria; Desiccation; Food Microbiology; Food Preservation; Food Preservatives; Fungi; Hydrogen-Ion Concentration; Meat; Nitrates; Penicillium; Sodium Chloride; Sodium Nitrite; Swine; Time Factors

An increase in suicide cases by sodium nitrate and sodium nitrite ingestion has been noted in the scientific literature. We report on the possible impact of nitrate/nitrite-caused methemoglobinemia on carboxyhemoglobin measurement by spectrophotometric methods. Elevated methemoglobin saturation may result in insufficient reducing agents to convert methemoglobin into deoxygenated hemoglobin, affecting the measured total hemoglobin and carboxyhemoglobin saturation. We highlight four cases where the cause of death was attributed to sodium nitrate or sodium nitrite ingestion. The possible impact of the nitrate/nitrite-caused methemoglobinemia on the carboxyhemoglobin saturation as measured by spectrophotometry is discussed. Further studies are needed to identify a causal relationship between nitrate/nitrite-caused methemoglobinemia and carboxyhemoglobin saturation as measured by spectrophotometric methods.

Topics: Carboxyhemoglobin; Humans; Methemoglobin; Methemoglobinemia; Nitrates; Sodium Nitrite

Topics: Adult; Aged; Aged, 80 and over; Blood; Female; Heart; Humans; Magnetic Resonance Imaging; Male; Methemoglobinemia; Middle Aged; Nitrates; Skin Pigmentation; Sodium Nitrite; Suicide, Completed; Young Adult

Hepatitis E virus (HEV) infection can cause acute and chronic hepatitis in humans. The zoonotic HEV genotype 3, which is highly prevalent in Europe, is mainly transmitted by consumption of raw meat and raw meat products produced from infected pigs or wild boars. High salt concentrations represent an important measure to preserve meat products and to inactivate foodborne pathogens. Here, an HEV preparation in phosphate-buffered saline (PBS) was subjected to different salt concentrations and the remaining infectivity was measured in a cell culture assay. Treatments with up to 20% sodium chloride for 24 h at 23 °C, with and without addition of 0.015% sodium nitrite or 0.03% sodium nitrate, did not lead to virus inactivation as compared to PBS only. Conditions usually applied for short-term and long-term fermented raw sausages were simulated by incubation at 22 °C for up to 6 days and at 16 °C for up to 8 weeks, respectively. Only 2% sodium chloride with 0.015% sodium nitrite showed a weak (< 1 log

Topics: Animals; Food Preservation; Food Preservatives; Hepatitis E; Hepatitis E virus; Humans; Meat Products; Nitrates; Sodium Chloride; Sodium Nitrite; Swine; Virus Inactivation

Dietary nitrate lowers blood pressure and improves athletic performance in humans, yet data supporting observations that it may increase cerebral blood flow and improve cognitive performance are mixed. We tested the hypothesis that nitrate and nitrite treatment would improve indicators of learning and cognitive performance in a zebrafish (Danio rerio) model. We utilized targeted and untargeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis to examine the extent to which treatment resulted in changes in nitrate or nitrite concentrations in the brain and altered the brain metabolome. Fish were exposed to sodium nitrate (606.9 mg/L), sodium nitrite (19.5 mg/L), or control water for 2-4 weeks and free swim, startle response, and shuttle box assays were performed. Nitrate and nitrite treatment did not change fish weight, length, predator avoidance, or distance and velocity traveled in an unstressed environment. Nitrate- and nitrite-treated fish initially experienced more negative reinforcement and increased time to decision in the shuttle box assay, which is consistent with a decrease in associative learning or executive function however, over multiple trials, all treatment groups demonstrated behaviors associated with learning. Nitrate and nitrite treatment was associated with mild anxiogenic-like behavior but did not alter epinephrine, norepinephrine or dopamine levels. Targeted metabolomics analysis revealed no significant increase in brain nitrate or nitrite concentrations with treatment. Untargeted metabolomics analysis found 47 metabolites whose abundance was significantly altered in the brain with nitrate and nitrite treatment. Overall, the depletion in brain metabolites is plausibly associated with the regulation of neuronal activity including statistically significant reductions in the inhibitory neurotransmitter γ-aminobutyric acid (GABA; 18-19%), and its precursor, glutamine (17-22%). Nitrate treatment caused significant depletion in the brain concentration of fatty acids including linoleic acid (LA) by 50% and arachidonic acid (ARA) by 80%; nitrite treatment caused depletion of LA by ~90% and ARA by 60%, change which could alter the function of dopaminergic neurons and affect behavior. Nitrate and nitrite treatment did not adversely affect multiple parameters of zebrafish health. It is plausible that indirect NO-mediated mechanisms may be responsible for the nitrate and nitrite-mediated effects on the brain metabolome and behavi

Topics: Animals; Anxiety; Arachidonic Acid; Association Learning; Behavior, Animal; Body Size; Body Weight; Brain; Dopamine; Epinephrine; Executive Function; Female; gamma-Aminobutyric Acid; Glutamine; Linoleic Acid; Male; Metabolome; Nitrates; Norepinephrine; Reflex, Startle; Reinforcement, Psychology; Sodium Nitrite; Zebrafish

Dysfunction in the nitric oxide (NO) signaling pathway can lead to the development of pulmonary hypertension (PH) in mammals. Discovery of an alternative pathway to NO generation involving reduction from nitrate to nitrite and to NO has motivated the evaluation of nitrite as an alternative to inhaled NO for PH. In contrast, inhaled nitrate has not been evaluated to date, and potential benefits include a prolonged half-life and decreased risk of methemoglobinemia. In a canine model of acute hypoxia-induced PH we evaluated the effects of inhaled nitrate to reduce pulmonary arterial pressure (PAP). In a randomized controlled trial, inhaled nitrate was compared to inhaled nitrite and inhaled saline. Exhaled NO, PAP and systemic blood pressures were continuously monitored. Inhaled nitrite significantly decreased PAP and increased exhaled NO. In contrast, inhaled nitrate and inhaled saline did not decrease PAP or increase exhaled NO. Unexpectedly, we found that inhaled nitrite resulted in prolonged (>5 h) exhaled NO release, increase in nitrate venous/arterial levels and a late surge in venous nitrite levels. These findings do not support a therapeutic role for inhaled nitrate in PH but may have therapeutic implications for inhaled nitrite in various disease states.

Topics: Administration, Inhalation; Animals; Dogs; Hypertension, Pulmonary; Hypoxia; Nitrates; Nitric Oxide; Rats; Sodium Nitrite

Topics: Ammonium Chloride; Arginine; Chlorella vulgaris; Cyclohexanols; Cyclohexenes; Eucalyptol; Eutrophication; Limonene; Lysine; Microcystis; Monoterpenes; Nitrates; Nitrogen; Photosynthesis; Serine; Sodium Nitrite; Terpenes; Urea; Volatile Organic Compounds

Nitrite has been traditionally used to control Clostridium botulinum in cured meat products. However, in the case of dry fermented sausages, environmental factors such as pH, aw and the competitive microbiota may exert a more relevant role than nitrite in the inhibition of the growth and toxin production by C. botulinum. In this challenge test study, two varieties of Mediterranean dry sausages (salchichón and fuet) were inoculated with spores of C. botulinum Group I (proteolytic) and C. botulinum Group II (nonproteolytic). Sausages were prepared with 150 mg/kg of NaNO3 and 150 mg/kg of NaNO2 (maximum ingoing amounts allowed by the European Union regulation), with a 25% and 50% reduction, and without nitrate/nitrite. The initial pH in both products was 5.6, and decreased to values below 5.0 in salchichón and to 5.2 in fuet. Lactic acid bacteria counts reached 8-9 log cfu/g after fermentation. The aw decreased from initial values of 0.96 to about 0.88-0.90 at the end of ripening. Botulinum neurotoxin was not detected in any of the sausages, including those manufactured without nitrate and nitrite. Despite the environmental conditions were within the range for germination and growth of C. botulinum Group I during the first 8 days of the ripening process in fuet and 10-12 days in salchichón, acidity, aw and incubation temperature combined to inhibit the production of toxin, independently of the concentration of curing agents. Although decreasing or even removing nitrate/nitrite from the formula did not compromise safety regarding C. botulinum in the conditions tested in this study, their antimicrobial role should not be underestimated in the case that other hurdles could fail or other ripening conditions were used, and also considering the effect of nitrite on other pathogens.

Topics: Animals; Bioreactors; Botulinum Toxins; Clostridium botulinum; Fermentation; Food Preservatives; Humans; Meat Products; Nitrates; Nitrogen Oxides; Sodium Nitrite; Spores, Bacterial; Swine; Temperature

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

Topics: Animals; Cattle; Clostridioides difficile; Food Microbiology; Food Preservatives; Meat; Microbial Sensitivity Tests; Nitrates; Sodium Nitrite; Sulfites; Swine

Dexrazoxane (DEX) is a clinically available cardioprotectant that reduces the toxicity induced by anthracycline (ANT) anticancer drugs; however, DEX is seldom used and its action is poorly understood. Inorganic nitrate/nitrite has shown promising results in myocardial ischemia-reperfusion injury and recently in acute high-dose ANT cardiotoxicity. However, the utility of this approach for overcoming clinically more relevant chronic forms of cardiotoxicity remains elusive. Hence, in this study, the protective potential of inorganic nitrate and nitrite against chronic ANT cardiotoxicity was investigated, and the results were compared to those using DEX. Chronic cardiotoxicity was induced in rabbits with daunorubicin (DAU). Sodium nitrate (1g/L) was administered daily in drinking water, while sodium nitrite (0.15 or 5mg/kg) or DEX (60mg/kg) was administered parenterally before each DAU dose. Although oral nitrate induced a marked increase in plasma NOx, it showed no improvement in DAU-induced mortality, myocardial damage or heart failure. Instead, the higher nitrite dose reduced the incidence of end-stage cardiotoxicity, prevented related premature deaths and significantly ameliorated several molecular and cellular perturbations induced by DAU, particularly those concerning mitochondria. The latter result was also confirmed in vitro. Nevertheless, inorganic nitrite failed to prevent DAU-induced cardiac dysfunction and molecular remodeling in vivo and failed to overcome the cytotoxicity of DAU to cardiomyocytes in vitro. In contrast, DEX completely prevented all of the investigated molecular, cellular and functional perturbations that were induced by DAU. Our data suggest that the difference in cardioprotective efficacy between DEX and inorganic nitrite may be related to their different abilities to address a recently proposed upstream target for ANT in the heart - topoisomerase IIβ.

Topics: Animals; Antibiotics, Antineoplastic; Cardiotonic Agents; Cardiotoxicity; Daunorubicin; Dexrazoxane; DNA Topoisomerases, Type II; DNA-Binding Proteins; Drug Administration Schedule; Infusions, Intravenous; Male; Myocardium; Myocytes, Cardiac; Nitrates; Rabbits; Sodium Nitrite

Streptococcus pneumoniaeis one of the key pathogens responsible for otitis media (OM), the most common infection in children and the largest cause of childhood antibiotic prescription. Novel therapeutic strategies that reduce the overall antibiotic consumption due to OM are required because, although widespread pneumococcal conjugate immunization has controlled invasive pneumococcal disease, overall OM incidence has not decreased. Biofilm formation represents an important phenotype contributing to the antibiotic tolerance and persistence ofS. pneumoniaein chronic or recurrent OM. We investigated the treatment of pneumococcal biofilms with nitric oxide (NO), an endogenous signaling molecule and therapeutic agent that has been demonstrated to trigger biofilm dispersal in other bacterial species. We hypothesized that addition of low concentrations of NO to pneumococcal biofilms would improve antibiotic efficacy and that higher concentrations exert direct antibacterial effects. Unlike in many other bacterial species, low concentrations of NO did not result inS. pneumoniaebiofilm dispersal. Instead, treatment of bothin vitrobiofilms andex vivoadenoid tissue samples (a reservoir forS. pneumoniaebiofilms) with low concentrations of NO enhanced pneumococcal killing when combined with amoxicillin-clavulanic acid, an antibiotic commonly used to treat chronic OM. Quantitative proteomic analysis using iTRAQ (isobaric tag for relative and absolute quantitation) identified 13 proteins that were differentially expressed following low-concentration NO treatment, 85% of which function in metabolism or translation. Treatment with low-concentration NO, therefore, appears to modulate pneumococcal metabolism and may represent a novel therapeutic approach to reduce antibiotic tolerance in pneumococcal biofilms.

Topics: Adenoids; Amoxicillin-Potassium Clavulanate Combination; Anti-Bacterial Agents; Biofilms; Child; Child, Preschool; Drug Resistance, Bacterial; Drug Synergism; Drug Therapy, Combination; Gene Expression Regulation, Bacterial; Humans; Hydrazines; Nitrates; Nitric Oxide; Nitric Oxide Donors; Nitroprusside; Otitis Media; Pneumococcal Infections; Protein Biosynthesis; Sodium Nitrite; Streptococcus pneumoniae; Transcription, Genetic

The effects of formulated sodium nitrate plus supplemental nitrate (SN) from celery juice powder on residual nitrite, residual nitrate, rancidity, microbial growth, color, sensory properties, and proximate composition of frankfurters, cotto salami and boneless ham during storage (1°C) were studied. The products were assigned one of two treatments, which were each replicated twice: control (156ppm sodium nitrite) or SN (156ppm sodium nitrite and 1718ppm sodium nitrate in combination with 2% VegStable 502). Sensory parameters and proximate composition were measured once for each replication. All other analytical measurements were conducted at regular intervals for 97-98days. The SN showed no increase in residual nitrite compared to the control. No changes (P>0.05) were observed in residual nitrate during storage for any of the products. The results showed that addition of SN did not significantly alter most physical, chemical or microbial properties of cured meat products during refrigerated storage, but some product dependent sensory effects were observed.

Topics: Animals; Apium; Colony Count, Microbial; Color; Consumer Behavior; Consumer Product Safety; Dietary Fats; Dietary Proteins; Food Contamination; Food Handling; Food Microbiology; Fruit and Vegetable Juices; Humans; Lactobacillus; Meat Products; Nitrates; Nitric Oxide; Nitrites; Sodium Nitrite; Swine; Taste; Thiobarbiturates

Nitrite anion has been demonstrated to be a prodrug of nitric oxide (NO) with positive effects on tissue ischemia/reperfusion injury, cytoprotection, and vasodilation. However, effects of nitrite anion therapy for ischemic tissue vascular remodeling during diabetes remain unknown. We examined whether sodium nitrite therapy altered ischemic revascularization in BKS-Lepr(db/db) mice subjected to permanent unilateral femoral artery ligation. Sodium nitrite therapy completely restored ischemic hind limb blood flow compared with nitrate or PBS therapy. Importantly, delayed nitrite therapy 5 days after ischemia restored ischemic limb blood flow in aged diabetic mice. Restoration of blood flow was associated with increases in ischemic tissue angiogenesis activity and cell proliferation. Moreover, nitrite but not nitrate therapy significantly prevented ischemia-mediated tissue necrosis in aged mice. Nitrite therapy significantly increased ischemic tissue vascular endothelial growth factor (VEGF) protein expression that was essential for nitrite-mediated reperfusion of ischemic hind limbs. Nitrite significantly increased ischemic tissue NO bioavailability along with concomitant reduction of superoxide formation. Lastly, nitrite treatment also significantly stimulated hypoxic endothelial cell proliferation and migration in the presence of high glucose in an NO/VEGF-dependent manner. These results demonstrate that nitrite therapy effectively stimulates ischemic tissue vascular remodeling in the setting of metabolic dysfunction that may be clinically useful.

Topics: Animals; Diabetes Mellitus, Type 2; Femoral Artery; Hindlimb; Ischemia; Mice; Neovascularization, Pathologic; Nitrates; Nitric Oxide; Sodium Nitrite; Time Factors; Vascular Endothelial Growth Factor A

Amphibians are declining worldwide and pollutants have been implicated as a major contributor to these declines. To understand these declines, many studies have assessed the impact of pollutants on amphibian behaviour. However, information regarding their effect on locomotor abilities, as well as the intra-specific variation of the tolerance to pollutants, is extremely rare. Further, the majority of studies examining the impact of pollutants on amphibians have been conducted in simplified laboratory settings. Given the complexity of natural systems, determining whether amphibian responses in laboratory studies can be generalized to more realistic natural scenarios is critical. Towards this goal, this study assessed the impact of nitrogenous pollution on survival and fitness-related larval traits (growth, mass and swimming performance) for three populations of the frog Pelophylax perezi, exposed to different degrees of eutrophication in two different and complementary experiments: (1) pond mesocosms, with NH4Cl isolated or combined with NaNO2 and NaNO3, and (2) field enclosures placed in natural streams differing in their degree of pollution. For both mesocosm and field enclosure experiments, larval mortality was unaffected by nitrogenous pollution. However, in the mesocosm experiment, exposure to nitrogenous compounds reduced final larvae mass and growth. In contrast, in the enclosure experiment, polluted locations facilitated final mass and growth of surviving tadpoles. Population-level variation in the effect of pollution was observed for final larval mass in the mesocosm but not in the field enclosure experiment. In addition, although nitrogenous compounds in both mesocosm and natural conditions had no direct effect on absolute larval swimming performance, they may impact the viability of larvae by affecting the relationships between growth and the swimming abilities. The differential pattern found in the impacts of nitrogenous compounds on larvae of P. perezi when raised in different experimental venues (mesocosms and field conditions) points to the convenience of considering more realistic natural scenarios in assessing the impact of pollutants on amphibians.

Topics: Ammonium Chloride; Animals; Anura; Larva; Motor Activity; Nitrates; Sodium Nitrite; Survival Analysis; Water Pollutants, Chemical

Nitric oxide (NO) is a critical negative regulator of platelets that is implicated in the pathology of thrombotic diseases. Platelets generate NO, but the presence and functional significance of NO synthase (NOS) in platelets is unclear. Inorganic nitrate/nitrite is increasingly being recognized as a source of bioactive NO, although its role in modulating platelets during health and vascular dysfunction is incompletely understood.. We investigated the functional significance and upstream sources of NO-cGMP signaling events in platelets by using established methods for assessing in vitro and in vivo platelet aggregation, and assessed the bioconversion of inorganic nitrate to nitrite during deficiency of endothelial NOS (eNOS).. The phosphodiesterase 5 (PDE5) inhibitor sildenafil inhibited human platelet aggregation in vitro. This inhibitory effect was abolished by a guanylyl cyclase inhibitor and NO scavengers, but unaffected by NOS inhibition. Inorganic nitrite drove cGMP-mediated inhibition of human platelet aggregation in vitro and nitrate inhibited platelet function in eNOS(-/-) mice in vivo in a model of thromboembolic radiolabeled platelet aggregation associated with an enhanced plasma nitrite concentration as compared with wild-type mice.. Platelets generate transient, endogenous cGMP signals downstream of NO that are primarily independent of NOS and may be enhanced by inhibition of PDE5. Furthermore, nitrite can generate transient NO-cGMP signals in platelets. The absence of eNOS leads to enhanced plasma nitrite levels following nitrate administration in vivo, which negatively impacts on platelet function. Our data suggest that inorganic nitrate exerts an antiplatelet effect during eNOS deficiency, and, potentially, that dietary nitrate may reduce platelet hyperactivity during endothelial dysfunction.

Topics: Animals; Blood Platelets; Cyclic GMP; Humans; Male; Mice, Inbred C57BL; Mice, Knockout; Nitrates; Nitric Oxide; Nitric Oxide Synthase Type III; Phosphodiesterase 5 Inhibitors; Platelet Aggregation; Platelet Aggregation Inhibitors; Second Messenger Systems; Sodium Nitrite; Time Factors

Nitrates and nitrites added to food can cause formation of cancerous N-nitroso compounds, whereas exposure to perchlorate is especially emphasised as an important risk factor for newborns' health. In this study, nitrate, nitrite and perchlorate concentrations in meat and milk products consumed in the Hatay region of Turkey were determined. Nitrate and nitrite were analysed with a spectrophotometric method, and perchlorate analysed via ion chromatography. The detected sodium nitrate and nitrite amounts in meat consumed in the Hatay region are less than the maximum levels as declared in the Turkish Food Codex. The amount of perchlorate was considered not to pose a threat as well. However, in 50% of the cheese samples, sodium nitrate amounts were found to be more than the maximum acceptable level in the Turkish Food Codex.

Topics: Animals; Anions; Cattle; Cheese; Dairy Products; Goats; Maximum Allowable Concentration; Meat; Meat Products; Milk; Nitrates; Nitrites; Perchlorates; Sheep; Sodium Nitrite; Turkey

The nitric oxide-specific fluorescent probe Fluorescent Nitric Oxide Cheletropic Trap (FNOCT) 8a was applied to intact tobacco (Nicotiana tabacum cv. Samsun) roots to detect sites of nitric oxide formation and NO distribution. Three week old tobacco seedlings were gently removed from the sand culture pots with intact roots and transferred to small Petri dishes, whose base was replaced by a thin coverslip. Intact roots were subjected to FNOCT 8a to localize NO-dependent fluorescence in these roots; controls with an exogenous NO donor confirmed the presence and distribution of the probe in the roots. To confirm the NO-dependent fluorescence, roots were incubated with the three different NO scavengers cPTIO {2-(4-Carboxyphenyl)-4,4,5,5-tetramethylimidazoline-L-oxyl-3-oxide}, methylene blue and sodium diethyl dithiocarbamate (DCC) followed by incubation with FNOCT 8a. Methylene blue and DCC were able to completely quench NO-dependent fluorescence, cPTIO quenched partially. The roots were incubated in the presence of NaNO₂ and NaNO₃, which are substrates for nitrite:nitric oxide reductase (NI-NOR) and plasma membrane-bound nitrate reductase (PM-NR), respectively. The NO-dependent fluorescence was more or less same at the root tips upon treatment with NaNO₂, while the overall fluorescence was reduced in the presence of NaNO. Fluorescence from the living roots was visualized by inverted confocal laser scanning microscope (CLSM) using UV laser (excitation 360 nm and emission 408 nm). A specialized apparatus has been devised by the authors for analysis of intact roots as described in the methods section of this paper. Intact roots were chosen for microscopic observation rather than incised roots to avoid production of NO due to stress or physical injury.

Topics: Cell Membrane; Cytosol; Fluorescent Dyes; Membrane Proteins; Microscopy, Confocal; Nicotiana; Nitrate Reductase; Nitrates; Nitric Oxide; Oxidoreductases; Plant Proteins; Plant Roots; Seedlings; Sodium Nitrite

Major advances in dissecting mechanisms of NO-induced down-regulation of the anti-tumour specific T-cell function have been accomplished during the last decade. In this work, we studied the effects of a NO donor (AT38) on leukaemic Jurkat cell bioenergetics. Culturing Jurkat cells in the presence of AT38 triggered irreversible inhibition of cell respiration, led to the depletion of 50% of the intracellular ATP content and induced the arrest of cell proliferation and the loss of cell viability. Although a deterioration of the overall metabolic activity has been observed, glycolysis was stimulated, as revealed by the increase of glucose uptake and lactate accumulation rates as well as by the up-regulation of GLUT-1 and PFK-1 mRNA levels. In the presence of NO, cell ATP was rapidly consumed by energy-requiring apoptosis mechanisms; under a glucose concentration of about 12.7mM, cell death was switched from apoptosis into necrosis. Exposure of Jurkat cells to DMSO (1%, v/v), SA and AT55, the non-NO releasing moiety of AT38, failed to modulate neither cell proliferation nor bioenergetics. Thus, as for all NSAIDs, beneficial effects of AT38 on tumour regression are accompanied by the suppression of the immune system. We then showed that pre-treating Jurkat cells with low concentration of cyclosporine A, a blocker of the mitochondrial transition pore, attenuates AT38-induced inhibition of cell proliferation and suppresses cell death. Finally, we have studied and compared the effects of nitrite and nitrate on Jurkat cells to those of NO and we are providing evidence that nitrate, which is considered as a biologically inert anion, has a concentration and time-dependent immunosuppressive potential.

Topics: Adenosine Triphosphate; Apoptosis; Cell Proliferation; Cell Respiration; Dose-Response Relationship, Drug; Energy Metabolism; Gene Expression Regulation, Leukemic; Glucose; Glucose Transporter Type 1; Glycolysis; Humans; Jurkat Cells; Lactates; Leukemia, T-Cell; Necrosis; Nitrates; Nitric Oxide; Nitric Oxide Donors; Phosphofructokinase-1; Reverse Transcriptase Polymerase Chain Reaction; Sodium Nitrite; Time Factors

The likely protective effects of nitric oxide (NO) against ammonium toxicity were investigated in the submerged macrophyte Hydrilla verticillata. The plants were subjected to ammonium stress (3mM ammonium chloride) in the presence of sodium nitroprusside (SNP, 10 μM), an NO donor. Treatment with SNP significantly increased the NO content and partially reversed the ammonium-induced negative effects, including membrane damage and the decrease in levels of chlorophyll, malondialdehyde, glutathione and ascorbic acid. Further, SNP application increased the catalytic activities of ascorbate peroxidase, superoxide dismutase, guaiacol peroxidase, catalase and glutathione S-transferase, but decreased that of NADH-oxidase. Histochemical staining showed that SNP application caused a significant decrease in the levels of superoxides and hydrogen peroxide. In contrast, application of other breakdown products of SNP (10 μM sodium ferrocyanide, 10 μM sodium nitrite and 10 μM sodium nitrate) failed to show any protective effect. The results suggest that the increased intracellular NO, resulting from SNP application, improved the antioxidant capacity of H. verticillata plants in coping with ammonium-induced oxidative stress.

Topics: Antioxidants; Ascorbic Acid; Chlorophyll; Ferricyanides; Glutathione Transferase; Hydrocharitaceae; Hydrogen Peroxide; Malondialdehyde; Multienzyme Complexes; NADH, NADPH Oxidoreductases; Nitrates; Nitric Oxide; Nitroprusside; Oxidative Stress; Quaternary Ammonium Compounds; Sodium Nitrite; Superoxides

Atrazine and nitrogenous fertilizers are agrochemical contaminants frequently detected in water systems in North America. Several studies reported their ability to affect amphibian and mammalian development. Retinoids, supplied in the diet or synthesized by cells, are essential to embryogenesis. Disturbance of their homeostasis may lead to teratogenic effects. Retinoic acid (RA) is a major retinoid regulator of cell proliferation and differentiation. Previous studies reported alterations of retinoid stores in bullfrogs of Yamaska River subwatersheds (Québec, Canada), a region of intensive agricultural activities associated with atrazine, nitrate, and nitrite contaminants. These contaminants could affect RA metabolism and RA-mediated processes. Mouse P19 embryonic stem cells, which can differentiate to neurons in response to RA, were used to test this hypothesis. Cells were cultured in the absence or presence of contaminants during neuroinduction with RA and assayed by flow cytometry for expression of stage-specific embryonic antigen-1 (SSEA1) (embryonic marker) and betaIII-tubulin (neuronal marker). Cell cultures were also analyzed for RA metabolism by high performance liquid chromotagraphy (HPLC). Downregulation of SSEA1 paralleled betaIII-tubulin upregulation in an RA concentration-dependent manner. Atrazine, nitrate, and nitrite did not affect differentiation at environmentally encountered micromolar concentrations. However, low molar nitrite prevented RA-induced SSEA1 downregulation and decreased betaIII-tubulin appearance. Decreased cell viability/proliferation accompanied these differentiation effects. P19 cells metabolized RA to polar retinoids. RA metabolism was not affected at any concentration of atrazine, nitrate, or nitrite. Environmentally relevant levels of these contaminants, thus, had no gross effect on neurodifferentiation and RA catabolism of embryonic stem cells. P19 cell-based bioassays may provide valuable tools in monitoring developmental toxicity.

Topics: Animals; Atrazine; Biomarkers; Cell Differentiation; Cell Line; Cell Proliferation; Cell Survival; Chromatography, High Pressure Liquid; Dose-Response Relationship, Drug; Embryonic Stem Cells; Environmental Monitoring; Fertilizers; Flow Cytometry; Lewis X Antigen; Mice; Neurons; Nitrates; Risk Assessment; Sodium Nitrite; Teratogens; Time Factors; Tretinoin; Tubulin; Water Pollutants, Chemical

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 a few samples back in 2002. The intake, mean and intake distribution of sodium nitrite have been calculated from 1998 to 2006 with data from the Danish dietary survey conducted in 2000-02 on Danes from four to 75 years of age. The amounts used by industry have been relatively stable through the whole period with levels varying between 6 and 20 mg sodium nitrite kg(-1) with sausages, meat for open sandwiches and salami-type sausages being the greatest contributors. The mean intake of sodium nitrate was around 1 mg day(-1), which is very low compared with the total intake of 61 mg day(-1). The mean intake of sodium nitrite was 0.017 and 0.014, 0.009 and 0.008, and 0.007 and 0.003 mg kg(-1) body weight day(-1) for men and women in the age groups 4-5, 6-14 and 15-75 years, respectively, which was much lower than the acceptable daily intake (ADI) of 0.09 mg kg(-1) body weight day(-1). The 99th percentile for the group of 4-year-olds was 0.107 and 0.123 mg kg(-1) body weight day(-1) for boys and girls, respectively, and the 95th percentile was 0.057 and 0.073 mg kg(-1) body weight day(-1) for boys and girls, respectively, highest for the girls. With fewer than 100 boys and girls in the 4-5-year age group, only very few persons were responsible for the high intake. The conversion of nitrate to nitrite in the saliva and the degradation of nitrite during production and storage must also be considered when evaluating the intake of nitrite.

Topics: Adolescent; Adult; Age Factors; Aged; Animals; Body Weight; Child; Child, Preschool; Denmark; Diet; Diet Surveys; Female; Food Additives; Humans; Male; Meat Products; Middle Aged; Nitrates; Sodium Nitrite

Apoptosis has been described in some parasites like Leishmania, Trypanosoma, and Trichomonas. This phenomenon has not been observed yet in Entamoeba histolytica. This work analyzed the in vitro effect of sodium nitroprusside, sodium nitrite and sodium nitrate (NOs) on E. histolytica apoptosis. Parasites incubated for 1h with NOs revealed apoptosis 6h later (95% viability), demonstrated by YOPRO-1, TUNEL, DNA fragmentation and low ATP levels. The caspase inhibitor Z-VAD-FMK inhibited total intracellular cysteine protease activity (CPA) but had no effect on apoptosis. When treated with NOs some amebic functions like complement resistance and hemolytic activity decreased but CPA and erythrophagocytosis remained unchanged. After treatment in vitro with NOs, parasite death was almost complete at 24h; but when injected into hamster livers they disappeared in less than 6h. These results show that apoptosis is induced in vitro by NOs in E. histolytica and renders them incapable of surviving in hamster's livers.

Topics: Animals; Apoptosis; Cricetinae; DNA Fragmentation; Entamoeba histolytica; In Situ Nick-End Labeling; Liver Abscess, Amebic; Male; Mesocricetus; Microscopy, Confocal; Nitrates; Nitric Oxide; Nitric Oxide Donors; Nitroprusside; Sodium Nitrite

The free radical peroxynitrite (ONOO-) is formed in biological systems from the reaction of nitric oxide (NO) with superoxide (O2-) and can react with protein and nonprotein thiol groups to produce tissue injury. However, these pathologic actions of (ONOO-) may have been overemphasized, in that (ONOO-) has vasorelaxant properties through activation of soluble guanylate cyclase; inhibits leukocyte-endothelial cell interactions; and reduces ischemia-reperfusion injury in the heart, lung, and liver. It has been reported that tolerance develops to the vasodilator actions of (ONOO-) and that (ONOO-) impairs vascular function. However, little, if anything, is known about responses to (ONOO-) in the hindlimb circulation of the cat. To better understand the effects of (ONOO-) on responses to vasoactive agonists and the mechanism by which (ONOO-) induces vasodilation, the effects of short-term exposure to (ONOO-) were investigated under constant-flow conditions in the hindlimb vascular bed of the cat. In these studies, direct intraarterial injections of (ONOO-) produced dose-dependent decreases in hindquarters perfusion pressure. The vasodilator responses to (ONOO-) were rapid in onset, were short in duration, and could be repeated without exhibiting tachyphylaxis. Vasodilator responses to (ONOO-) were not changed in the presence of inhibitors of nitric-oxide synthase, cyclooxygenase, or K+-ATP (adenosine triphosphate-sensitive potassium) channels. Furthermore, responses to (ONOO-) were enhanced in duration by the type 5-cGMP (cyclic guanosine monophosphate) phosphodiesterase inhibitor zaprinast, whereas rolipram, a type 4-cGMP phosphodiesterase inhibitor, was without effect. Repeated administration of (ONOO-) had no significant effect on responses to vasoconstrictor or to vasodilator agents including acetylcholine. These results show that (ONOO-) has significant vasodilator activity in the hindlimb vascular bed of the cat and suggest that the response is mediated by a cGMP- dependent mechanism. The results of experiments with repeated injections of (ONOO-) indicate that (ONOO-) does not impair vasoconstrictor and endothelium-dependent or endothelium-independent vasodilator responses. Furthermore, tolerance did not develop with repeated short-term exposure to (ONOO-). Moreover, the results of experiments with inhibitors suggest that responses to (ONOO-) are not dependent on K-ATP (adenosine triphosphate-sensitive potassium) channel activation, increased NOS activi

Topics: 3',5'-Cyclic-GMP Phosphodiesterases; Adamantane; Animals; Cats; Female; Hindlimb; Male; Meclofenamic Acid; Morpholines; NG-Nitroarginine Methyl Ester; Nitrates; Nitric Oxide Donors; Perfusion; Peroxynitrous Acid; Phosphodiesterase Inhibitors; Potassium Channel Blockers; Purinones; Regional Blood Flow; Rolipram; Sodium Nitrite; Splanchnic Circulation; Vascular Resistance; Vasoconstrictor Agents; Vasodilator Agents

A 22-year-old woman with an initial diagnosis of 'ruptured ectopic pregnancy' and 'hemorrhagic shock' was sent to the operation room for surgical treatment. The mucocutaneous color was deeply cyanosed and the pulse oximeter oxygen saturation (SpO2) was only 86% after tracheal intubation (100% O2). 'Chocolate-brown' blood was observed and methemoglobinemia was considered. Then the arterial blood gas (ABG) sample was obtained, an intravenous infusion of methylene blue and vitamin C followed. The patient recovered quickly, and later two other patients with similar symptoms were treated in the same way. The success was due to a correct diagnosis accompanied with prompt treatment and quick recognition of the etiology.

Topics: Adult; Antidotes; Antioxidants; Ascorbic Acid; Blood Gas Analysis; Diagnosis, Differential; Female; Food Preservatives; Humans; Meat; Methemoglobinemia; Methylene Blue; Nitrates; Oxygen; Pregnancy; Pregnancy, Ectopic; Rupture; Shock, Hemorrhagic; Sodium Nitrite

We tested a mixture of NaOH and carbon and found it to react rapidly with NO gas, thus demonstrating a promising new method of flue gas denitrification (FGD). We determined the reaction products: gas phases were analyzed by GC-MS and NOx meter, and solid residues were analyzed by X-ray diffusion (XRD) and chemical analysis. The reaction process was clearly divided into two stages. In the first stage, the reaction proceeded extremely rapidly, with NO almost completely removed. The mechanism describing this stage consists of a series of reactions of NaOH and NO in the presence of carbon. The main conversion of sodium in this stage is proposed to be: NaOH-->NaNO3 (and NaNO2)-->Na2O2-Na2CO3. The pyrolysis of NaNO3 was examined and carbon was found to have the ability to reduce NOx emission during this process. In the second stage, NO reduction proceeds slowly and stabilizes at a constant value. The mechanism behind this stage is considered to be the reaction of carbon with NO in the presence of Na2-CO3 as catalyst. Quantitative study of the reaction system demonstrated that the total amount of denitrified NO is proportional to the amount of carbon and that the denitrified NO in the first stage is proportional to the amount of NaOH.

Topics: Absorptiometry, Photon; Air Pollutants; Carbon; Carbonates; Catalysis; Diffusion; Gas Chromatography-Mass Spectrometry; Incineration; Models, Chemical; Nitrates; Nitric Oxide; Nitrites; Peroxides; Sodium Hydroxide; Sodium Nitrite; Time Factors

The effects of peroxynitrite (ONOO-) on vascular responses were investigated in the systemic and hindquarters vascular bed and in the isolated perfused rat lung. Intravenous injections of ONOO- decreased systemic arterial pressure, and injections of ONOO- into the hindquarters decreased perfusion pressure in a dose-related manner. Injections of ONOO- into the lung perfusion circuit increased pulmonary arterial perfusion pressure. Responses to ONOO- were rapid in onset, short in duration, and repeatable without exhibiting tachyphylaxis. Repeated injections of ONOO- did not alter systemic, hindquarters, or pulmonary responses to endothelium-dependent vasodilators or other vasoactive agonists and did not alter the hypoxic pulmonary vasoconstrictor response. Injections of sodium nitrate or nitrite or decomposed ONOO- had little effect on vascular pressures. Pulmonary and hindquarters responses to ONOO- were not altered by a cyclooxygenase inhibitor in a dose that attenuated responses to arachidonic acid. These results demonstrate that ONOO- has significant pulmonary vasoconstrictor, systemic vasodepressor, and vasodilator activity; that short-term repeated exposure does impair vascular responsiveness; and that responses to ONOO- are not dependent on cyclooxygenase product release.

Topics: Anesthesia; Animals; Blood Pressure; Hypoxia; Male; Nitrates; Peroxynitrous Acid; Pulmonary Circulation; Rats; Rats, Sprague-Dawley; Sodium Nitrite; Vascular Resistance; Vasoconstriction; Vasodilation

The effects of a range of nitric oxide (NO)-related compounds on histamine release from human basophils and rat peritoneal mast cells were studied. Basal and immunologic histamine releases from human basophils were not affected by N(omega)-nitro-L-arginine, N(omega)-nitro-L-arginine methyl ester, aminoguanidine or methylene blue (all inhibitors of NO production), sodium nitroprusside (an NO donor), L-arginine (a substrate for NO synthase) or D-arginine (the inactive enantiomer of L-arginine). In rat peritoneal mast cells, NO donors such as sodium nitroprusside, sodium nitrite and sodium nitrate, and lipopolysaccharide (an inducer of NO synthase) had little effect on basal histamine release, while 3-morpholino-sydnonimine (SIN-1, an NO donor), L-arginine and D-arginine increased this release by up to threefold. None of the inhibitors of NO production had any striking effect on histamine release induced by anti-rat immunoglobulin E (IgE), compound 48/80, sodium fluoride, phospholipase C, 1,2-dioctanoyl-sn-glycerol or ionophore A23187. However, haemoglobin was found to inhibit histamine release by anti-rat IgE or A23187 by ca. 40%. Alone of the NO donors, low concentrations of L-arginine produced a mild inhibition of histamine release induced by anti-IgE, compound 48/80 and A23187, but not other ligands, while sodium nitroprusside dose-dependently inhibited (by a maximum of ca. 30%) histamine release by anti-rat IgE, sodium fluoride or A23187. Stimulation with a variety of secretagogues or treatment with L-arginine, D-arginine, lipopolysaccharide, SIN-1 or sodium nitroprusside had no effect on NO production. Similarly, L-arginine, D-arginine or sodium nitroprusside did not change intracellular cGMP levels. On the basis of these results, it is suggested that NO does not play a significant role in the modulation of histamine release from human basophils or rat peritoneal mast cells. The effects of L-arginine, D-arginine and sodium nitroprusside may involve mechanisms unrelated to NO.

Topics: Animals; Antibodies; Arginine; Basophils; Calcimycin; Dose-Response Relationship, Drug; Guanidines; Hemoglobins; Histamine; Humans; Immunoglobulin E; Male; Mast Cells; Methylene Blue; Molsidomine; NG-Nitroarginine Methyl Ester; Nitrates; Nitric Oxide; Nitric Oxide Donors; Nitroarginine; Nitroprusside; p-Methoxy-N-methylphenethylamine; Peritoneal Cavity; Rats; Rats, Sprague-Dawley; Sodium Fluoride; Sodium Nitrite

The aim of this study was to observe the dynamics of nitrates and nitrites during the six stages of manufacture of Emmental cheeses. Samples were taken of untreated milk, of pasteurized milk, of milk with nitrates added, of pressed cheese curd, of whey, of maturing cheese and of the final product. The samples were drawn from a commercial operation in a cheese factory in the eastern part of Slovakia. The mean NaNO2 content in untreated and in pasteurised milk was 0.2 and 0.1 mg kg-1, respectively and the mean NaNO3 content was 0.9 and 0.9 mg kg-1 respectively. Nitrates were added to the milk to prevent 'blowing' of hard cheese by micro organisms. In milk with nitrate added the mean content was 81.2 mg kg-1 NaNO3; the maximum value being 90.0 mg kg1 NaNO3. After pressing, the mean value of nitrate was found to be 20.6 mg kg-1 NaNO3. A considerable quantity of nitrates passed into the whey, where the mean nitrate content was 67.0 mg kg-1 NaNO3. The final product had a markedly decreased content of nitrates (3.3 mg kg-1 NaNO3) and nitrites (0.2 mg kg-1 NaNO2) when compared with the values in cheese during maturation (11.3 mg kg-1 NaNO3; 0.4 mg kg-1 NaNO2).

Topics: Cheese; Food Handling; Nitrates; Slovakia; Sodium Nitrite

The aim of the present study was to explore the mechanisms by which nitric oxide (NO) may inhibit aromatase activity of human granulosa cells. Ovarian granulosa-luteal cells, obtained from patients undergoing in-vitro fertilization (IVF) were cultured in the presence of NO-related substances. After 24 h of culture, aromatase activity of the cells was significantly inhibited by treatment with the NO donors, SNAP or NOC12 at > or =10(-4) M in a dose-dependent manner. Treatment with NO catabolites or a peroxynitrite-releasing compound, SIN1, had no significant influence. Treatment with SNAP at 10(-3) M decreased relative aromatase mRNA values by 72% (P<0.05) and intracellular cyclic AMP concentrations by 53% (P<0.01). However, treatment with H89, an inhibitor of protein kinase A, did not inhibit aromatase activity. Since there were no significant effects of NO catabolites or peroxinitrite, the inhibitory action of NO donors on aromatase must be related to NO release. The action of NO is, in part, attributable to the down-regulation of aromatase gene transcription. Although NO decreased intracellular cAMP values, down-regulation of aromatase gene transcription may not be mediated by protein kinase A-dependent mechanisms.

Topics: Adult; Aromatase; Aromatase Inhibitors; Cells, Cultured; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Enzyme Inhibitors; Female; Gene Expression Regulation; Granulosa Cells; Humans; Isoquinolines; Nitrates; Nitric Oxide; Penicillamine; Protein Kinase C; Sodium Nitrite; Sulfonamides; Tetradecanoylphorbol Acetate; Transcription, Genetic

The measurement of the total level of nitric oxide (NO) metabolite (NO(x)(-)) by microdialysis has recently been used to assess the production of NO in the in vivo brain [D. Luo, S. Knezevich, S.R. Vincent, N-Methyl-D-aspartate-induced nitric oxide release: an in vivo microdialysis study, Neuroscience, 57 (1993), 897-900; K. Ohta, N. Arai, M. Shibata, J. Hamada, S. Komatsumoto, K. Shimazu, Y. Fukuuchi, A novel in vivo system for consecutive measurement of brain nitric oxide production combined with the microdialysis technique, Neurosci. Lett., 176 (1994), 165-168; K. Shintani, S. Kanba, T. Nakai, K. Sato, G. Yagi, R. Kato, M. Arai, Measurement by in vivo microdialysis of nitric oxide release in the rat cerebellum, J. Psychiatr. Neurosci., 3 (1994), 217-221; H. Togashi, K. Mori, K. Ueno, M. Matsumoto, N. Suda, H. Saito, M. Yoshika, Consecutive evaluation of nitric oxide production after transient cerebral ischemia in the rat hippocampus using in vivo brain microdialysis, Neurosci. Lett., 240 (1998), 53-57]. Although several methods are available for detecting NO(x)(-) levels in dialysates, these methods are either not sensitive enough or require expensive experimental equipment. The method described herein provides a convenient and sensitive procedure for determining NO(x)(-) levels in dialysates. This method is useful for the in vivo study of NO production from various brain regions in various pathological conditions, and can be applied to other tissues.

Topics: Animals; Brain Ischemia; Corpus Striatum; Gerbillinae; Male; Microdialysis; Nitrates; Nitric Oxide; Sodium Nitrite

The enzyme 3-methylaspartase (3-methylaspartate ammonia-lyase, EC 4. 3.1.2) was found in the cells of enteric bacteria, especially in the genera Citrobacter and Morganella, that were grown under anoxic and oxygen-limited conditions. The enzymes were purified to homogeneity from the cell-free extracts of 18 active strains and had similar enzymological properties such as action on columns, specific activity, molecular weight, subunit structure, and N-terminal amino acid sequence similarity. The production of the enzyme was dependent on the limitation of oxygen during growth and was arrested by aeration. The addition of external electron acceptors such as dimethylsulfoxide could support cell growth and production of the enzyme. Activities of glutamate mutase (EC 5.4.99.1) and (S)-citramalate hydrolyase (EC 4.2.1.34), key enzymes of the mesaconate pathway of (S)-glutamate fermentation in the genus Clostridium, were detected in the cells of the active strains grown under oxygen-limited conditions. Based on the results, the mesaconate pathway is proposed to explain the (S)-glutamate fermentation process observed in Enterobacteriaceae, and 3-methylaspartase could be a marker enzyme for this pathway.

Topics: Aerobiosis; Amino Acid Sequence; Ammonia-Lyases; Biomarkers; Citrobacter freundii; Dimethyl Sulfoxide; Electron Transport; Enterobacteriaceae; Fermentation; Glutamates; Hydro-Lyases; Intramolecular Transferases; Klebsiella; Molecular Sequence Data; Nitrates; Sodium Nitrite

Nitric oxide (NO) synthase is a hemoprotein containing several cysteinyl residues including thiolate as its proximal heme ligand. Exposure to NO is known to induce S-nitrosylation of protein thiols and modulation of enzyme activities, including the catalytic activity of NO synthase. Because S-nitrosylation of vicinal thiols promotes disulfide formation, we determined whether exposure to NO results in modulation of the catalytic activity of NO synthase and whether disulfide reduction catalyzed by thioredoxin/thioredoxin reductase (T/TR) and/or by glutaredoxin restores the catalytic activity of NO synthase in pulmonary artery endothelial cells (PAEC). Exposure of intact PAEC, isolated total membranes, plasma membranes, or purified NO synthase to NO significantly reduced NO synthase catalytic activity. Similarly, exposure of isolated total membranes or purified NO synthase to potassium ferricyanide (FeCN) also reduced catalytic activity of NO synthase in a concentration-dependent fashion. Although the catalytic activity of NO synthase was significantly reduced following exposure of intact cells to NO, the expression of NO synthase mRNA was unchanged. NO synthase activity in intact cells or isolated membranes exposed to nitrate, nitrite, or 10 ppm nitrogen dioxide gas was comparable to controls. Incubation in the presence of oxyhemoglobin prevented but did not reverse NO-induced inhibition of NO synthase. Incubation in the presence of T/TR but not glutaredoxin reversed NO-induced reduction of NO synthase activity and a purified enzyme preparation exposed directly to NO. Similarly, FeCN-induced reduction of NO synthase activity was also reversed in the presence of T/TR but not by glutaredoxin. These results demonstrate that the interaction of NO with the regulatory domain of NO synthase protein is responsible for post-translational reduction of its catalytic activity. Thioredoxin-regulated reversal of NO-induced modulation of NO synthase protein suggests that an oxidative conformational change in vicinal thiols, resulting in the formation of intramolecular or intermolecular disulfides or both, is involved.

Topics: Allosteric Regulation; Animals; Antioxidants; Bacterial Proteins; Biopterins; Carcinogens; Cells, Cultured; Endothelium, Vascular; Ferricyanides; Glutaredoxins; Lung; Nitrates; Nitric Oxide; Nitric Oxide Synthase; Oxidative Stress; Oxidoreductases; Oxyhemoglobins; Protein Processing, Post-Translational; Proteins; Pulmonary Artery; RNA, Messenger; Sodium Nitrite; Sulfhydryl Compounds; Superoxide Dismutase; Swine; Thioredoxins

The paper deals with the experimental findings regarding the effects of non-radiational factors, such as sodium nitrite and nitrate and increased temperature, on the metabolism kinetics of 14C inorganic and organic compounds (14C-sodium bicarbonate, 14C-glucose) in conditions of long-term internal exposure to the nuclide. The authors determined the time which elapses before the steady state is achieved as well as the maximum concentration, the accumulation factor and the dose strength. At a concentration of 3 g/l, nitrites and nitrates were shown to produce no significant modifying effect on the kinetics of 14C metabolism. In hyperthermic conditions, 14C metabolism proved to be more intensive. The findings reported herein may have practical applications in setting up hygienic norms and evaluating the hazards of 14C accumulation in the environment.

Topics: Adipose Tissue; Animals; Bicarbonates; Bone and Bones; Carbon Radioisotopes; Glucose; Hot Temperature; Liver; Nitrates; Nitrites; Rats; Sodium; Sodium Bicarbonate; Sodium Nitrite

Both soluble and microsomal fractions of Fusarium oxysporum contain cytochrome P-450(P-450). We report here that the P-450 in the soluble fraction was induced only when nitrate or nitrite was added to the growth medium, whereas the microsomal P-450 was synthesized regardless of the medium compositions. The reduced-CO complex of the soluble P-450 exhibited an absorption spectrum that is different from that of the microsomal counterpart. These results indicate that the soluble P-450 is distinct from the microsomal species and suggest a novel function for the former P-450.

Topics: Carbon Monoxide; Cytochrome P-450 Enzyme System; Enzyme Induction; Fusarium; Microsomes; Nitrates; Nitrites; Sodium Nitrite; Solubility; Spectrophotometry

Piperazine has been shown to nitrosate in vivo to N-mononitrosopiperazine (MNPZ) by oral intake. Urine from workers exposed to piperazine in a chemical plant was analysed for nitrosamines by gas chromatography-thermal energy analysis. In five out of 11 exposed cases, MNPZ excretion in urine was 0.3 to 4.7 micrograms/24 h (during and after a work shift). In four cases, MNPZ was detected in some urine samples, and in two cases MNPZ was not detected (less than 0.1 ng/ml). The individual excretion was strongly dependent on piperazine exposure, which ranged from 0.06 to 1.7 mg/m3 (time-weighted average; Spearman's rank correlation 0.78, P = 0.01). The MNPZ excretion showed no significant correlation with nitrite or nitrate in saliva (both: r = 0.50, P = 0.10).

Topics: Adult; Air Pollutants, Occupational; Chemical Industry; Humans; Male; Middle Aged; Nitrates; Nitrosamines; Piperazine; Piperazines; Saliva; Sodium Nitrite

The in vivo interaction of sulphadimidine (SDM) with nitrite and nitrate has been investigated in pigs. It was shown that the combined oral treatment with SDM and nitrite but not nitrate leads to the formation of a deaminated compound, which becomes the major metabolite in plasma soon after cessation of the treatment. The major in vitro reaction product, 1,3-di(4-[N(4,6-dimethyl-2-pyrimidinyl)]-sulphamoylphenyl)-triazen e, DDPSPT as has been reported previously, could not be detected in blood, urine or faeces of the exposed animals. No effect of nitrite or nitrate could be observed on the acetylation of SDM.

Topics: Administration, Oral; Animals; Drug Interactions; Female; Nitrates; Nitrites; Sodium Nitrite; Sulfamethazine; Swine; Triazenes

1. The influence of nitrate and nitrite on net absorption of electrolytes (Na+, K+, Cl-) and water from ligated loops was studied at various intestinal sites in rats. 2. Nitrate strikingly reduced Cl- absorption in rat proximal and distal colon, whereas Na+ absorption was reduced only moderately. Nitrite also reduced Cl- absorption in the colon. 3. Nitrate showed no significant effect on electrolyte absorption in the small intestine. 4. The results suggest that Cl-/HCO3- on exchange is the major route of Cl- absorption in the colon, whereas this mechanism seems not to be of importance for Cl- absorption by the small intestine.

Topics: Animals; Chlorides; Colon; Ileum; In Vitro Techniques; Intestinal Absorption; Intestine, Small; Jejunum; Kinetics; Male; Nitrates; Nitrites; Potassium; Rats; Rats, Inbred Strains; Sodium; Sodium Nitrite

Topics: Animals; Cocarcinogenesis; Drug Synergism; Female; Lung Neoplasms; Mammary Neoplasms, Experimental; Nitrates; Nitrites; Rats; Sodium Nitrite; Tritium; Water; Water Intoxication

Nitrosation of dipeptides which do not contain imino acids leads to rearrangement and the formation of N-nitrosoiminodialkanoic acids. The optimum conditions for the nitrosation of dipeptides in buffer solutions occur at pH 2.0 (0.8-3.2% yield) and are not significantly catalysed by thiocyanate. In vitro nitrosation in gastric juice resulted in a lower yield. It was demonstrated that under normal gastric conditions, a maximum yield of 0.1 mumol total N-nitrosoiminodialkanoic acids/0.1 mol dipeptide would occur, 0.1 mol representing a typical dietary intake of dipeptide. This corresponds to a total concentration of approximately 20 micrograms/l N-nitrosoiminodialkanoic acids over a 24 h period. However, this figure may be significantly altered due to the fluctuation of nitrosation catalysts and inhibitors in gastric juice. Further studies showed that N-nitrosoiminodialkanoic acids are quantitatively excreted in urine when fed by gavage to rats. However, co-administration of the precursor dipeptide and nitrite resulted in negligible in vivo formation. The presence of N-nitrosoiminodialkanoic acids in normal human urine was not detected. Thus it was concluded that the monitoring of N-nitrosoiminodialkanoic acids in human urine is not a suitable method for biological monitoring of the endogenous nitrosation of dipeptides.

Topics: Animals; Dipeptides; Gastric Juice; Humans; Hydrogen-Ion Concentration; Male; Monitoring, Physiologic; Nitrates; Nitroso Compounds; Rats; Rats, Inbred Strains; Sodium Nitrite

Endogenous formation of N-nitrosodi-n-butylamine (NDBA) was studied in rats after administration of sodium nitrite or sodium nitrate and N,N-dibutylamine (DBA) by monitoring the urinary excretion of NDBA and its metabolites, N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN) and N-butyl-N-(3-carboxypropyl)nitrosamine (BCPN). Animals were given sodium nitrite (0.2%) or sodium nitrate (0.5%), dissolved in the drinking-water. This treatment was started 24 h before DBA administration and was continued throughout the experiment. Animals were fasted overnight before receiving DBA, which was administered by gavage as three doses of 50 mg/kg, 8 h apart; 24-h urine samples were collected on ammonium sulfamate. NDBA, BBN and BCPN were extracted and analysed by GC-TEA, according to a method previously described. Under the experimental conditions reported, NDBA and BBN (free or glucuronic acid-conjugated) were not detected in the urine of animals given nitrite or nitrate and DBA, but the presence of BCPN indicated that N-nitrosation had occurred in both groups of animals. These results suggest that, when studying nitrosamines that are extensively metabolized, quantitative analysis of urinary metabolites is a better indicator of nitrosamine exposure than measurement of nitrosamine itself.

Topics: Animals; Butylamines; Butylhydroxybutylnitrosamine; Environmental Exposure; Male; Nitrates; Nitrosamines; Rats; Sodium Nitrite

The knowledge of the amounts of nitrates and nitrites consumed by the child population is of great importance due to three fundamental aspects: Reduction of nitrates to nitrites. Relation of these to methemoglobinemia. Carcinogenicity of the N-nitroso compounds, of which nitrites are the precursors. In the present article information is given as to the estimated amounts of nitrates and nitrites, which about 10 000 children between one and six years of age, who attend State Nurseries in the City of Havanna, may consume through the daily intake of food, milk and water offered by the Centralized Kitchen "Cuba-Finland Friendship". The method of analysis used to determine nitrates and nitrites is that reported by the Mixed Committee FAO/OMS in 1976, using a reducing column containing cadmium described by FOLLET et al. in 1963. The statistical method employed is the t-Test of the comparison of media. Estimated quantities of nitrates and nitrites, which these children may consume according to the offer of food, milk and water they receive, are: 25.6 mg of NaNO3 and 1.04 mg of NaNO2 for children one to three years of age, and 36.1 mg of NaNO3 and 1.48 mg of NaNO2 for children four to six. These values lie under those recommended as admissible daily intake reported by the Mixed Committee FAO/OMS. Therefore, there does not seem to exist a risk to health through consumption of nitrates and nitrites by the population under investigation.

Topics: Animals; Child; Child Day Care Centers; Child, Preschool; Cuba; Female; Food; Food Analysis; Humans; Infant; Milk; Nitrates; Nitrites; Sodium Nitrite; State Medicine; Water Supply

The nitrate and nitrite contents in cheese of the Gouda type, produced by the Milk Complex of Havanna, were investigated and compared with those found in 5 types of imported cheese consumed in Cuba. No significant differences were found in the mean value (mean) of NaNO3, whereas in the mean value (mean) of NaNO2 differences were found when comparing all cheeses against each other. From these results it is inferred that the consumption of Gouda type cheese does not represent an important contribution to the daily intake of nitrates and nitrites, precursors in the synthesis of cancerogenic N-nitroso compounds.

Topics: Cheese; Cuba; Food Handling; Nitrates; Nitrites; Sodium Nitrite

Topics: Animals; Body Weight; Carbaryl; Male; Nitrates; Nitrites; Organ Size; Rats; Rats, Inbred Strains; Sodium Nitrite; Time Factors

Topics: Animals; Homovanillic Acid; Kinetics; Nitrates; Nitrites; Phenylacetates; Rats; Rats, Inbred Strains; Sodium Nitrite; Vanilmandelic Acid

Topics: Blood Pressure; Blood Pressure Determination; Humans; Hypertension; Nitrates; Sodium Nitrite