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1.
Redox Biol ; 26: 101291, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31421409

RESUMO

Nitrite and H2O2 are long-lived species in cold atmospheric plasma and plasma-activated medium. It is known that their synergistic interaction is required for selective apoptosis induction in tumor cells that are treated with plasma-activated medium. This study shows that the interaction between nitrite and H2O2 leads to the formation of peroxynitrite, followed by singlet oxygen generation through the interaction between peroxynitrite and residual H2O2. This primary singlet oxygen causes local inactivation of few catalase molecules on the surface of tumor cells. As a consequence, H2O2 and peroxynitrite that are constantly produced by tumor cells and are usually decomposed by their protective membrane-associated catalase, are surviving at the site of locally inactivated catalase. This leads to the generation of secondary singlet oxygen through the interaction between tumor cell-derived H2O2 and peroxynitrite. This selfsustained process leads to autoamplification of secondary singlet oxygen generation and catalase inactivation. Inactivation of catalase allows the influx of H2O2 through aquaporins, leading to intracellular glutathione depletion and sensitization of the cells for apoptosis induction through lipid peroxidation. It also allows to establish intercellular apoptosis-inducing HOCl signaling, driven by active NOX1 and finalized by lipid peroxidation through hydroxyl radicals that activates the mitochondrial pathway of apoptosis. This experimentally established model is based on a triggering function of CAP and PAM-derived H2O2/nitrite that causes selective cell death in tumor cells based on their own ROS and RNS. This model explains the selectivity of CAP and PAM action towards tumor cells and is in contradiction to previous models that implicated that ROS/RNS from CAP or PAM were sufficient to directly cause cell death of tumor cells.


Assuntos
Morte Celular/efeitos dos fármacos , Peróxido de Hidrogênio/metabolismo , Nitritos/metabolismo , Gases em Plasma , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Humanos , Peróxido de Hidrogênio/farmacologia , Cinética , Redes e Vias Metabólicas , Óxido Nítrico/metabolismo , Nitritos/farmacologia , Oxirredução/efeitos dos fármacos , Gases em Plasma/farmacologia , Espécies Reativas de Oxigênio/metabolismo
2.
Redox Biol ; 26: 101301, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31442912

RESUMO

Treatment of tumor cells with H2O2 and nitrite, two long-lived species derived from cold atmospheric plasma, induces a complex autoamplificatory, singlet oxygen-mediated process, which leads to catalase inactivation and reactivation of intercellular apoptosis-inducing signaling. Experimental dissection and quantification of this process is described in this study. When tumor cells were pretreated with H2O2 and nitrite, and then were added to untreated tumor cells, they propaged singlet oxygen mediated catalase inactivation and generation of singlet oxygen to the untreated cell population. This bystander effect allowed to analyze the biochemical requirements of a) induction of the bystander effect-inducing potential, b) transmission of the bystander effect to untreated neighbouring cells, and c) the biochemical consequences of these signaling events. The induction of bystander effect-inducing potential requires the generation of "primary singlet oxygen" through the reactions following the interaction between nitrite and H2O2, followed by local inactivation of a few catalase molecules. This primary effect seems to be very rare, but is efficiently enhanced by the generation of "secondary singlet oxygen" through the interaction between H2O2 and peroxynitrite at the site of inactivated catalase. Transmission of bystander signaling between pretreated and untreated tumor cells depends on the generation of secondary singlet oxygen by the pretreated cells and singlet oxygen-mediated catalase inactivation of the untreated recipient cells. This induces autoamplificatory propagation of secondary singlet oxygen generation in the population. This experimental approach allowed to quantify the efficiencies of primary and secondary singlet oxgen generation after CAP and PAM action, to dissect the system and to study the underlying chemical biology in detail. Our data confirm that CAP and PAM-derived components are merely the trigger for the activation of autoamplificatory mechanisms of tumor cells, whereas the tumor cells efficiently propagate their cell death through their own ROS/RNS signaling potential.


Assuntos
Gases em Plasma/farmacologia , Transdução de Sinais/efeitos dos fármacos , Oxigênio Singlete/metabolismo , Oxirredutases do Álcool/metabolismo , Apoptose/efeitos dos fármacos , Caspases/metabolismo , Linhagem Celular Tumoral , Relação Dose-Resposta a Droga , Humanos , Peróxido de Hidrogênio/metabolismo , Peróxido de Hidrogênio/farmacologia , Espaço Intracelular/metabolismo , Redes e Vias Metabólicas , Modelos Biológicos , NADPH Oxidase 1/metabolismo , Óxido Nítrico/metabolismo , Nitritos/metabolismo , Nitritos/farmacologia
3.
PLoS One ; 14(6): e0216401, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31158231

RESUMO

Mucoid mucA22 Pseudomonas aeruginosa (PA) is an opportunistic lung pathogen of cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD) patients that is highly sensitive to acidified nitrite (A-NO2-). In this study, we first screened PA mutant strains for sensitivity or resistance to 20 mM A-NO2- under anaerobic conditions that represent the chronic stages of the aforementioned diseases. Mutants found to be sensitive to A-NO2- included PA0964 (pmpR, PQS biosynthesis), PA4455 (probable ABC transporter permease), katA (major catalase, KatA) and rhlR (quorum sensing regulator). In contrast, mutants lacking PA0450 (a putative phosphate transporter) and PA1505 (moaA2) were A-NO2- resistant. However, we were puzzled when we discovered that mucA22 mutant bacteria, a frequently isolated mucA allele in CF and to a lesser extent COPD, were more sensitive to A-NO2- than a truncated ΔmucA deletion (Δ157-194) mutant in planktonic and biofilm culture, as well as during a chronic murine lung infection. Subsequent transcriptional profiling of anaerobic, A-NO2--treated bacteria revealed restoration of near wild-type transcript levels of protective NO2- and nitric oxide (NO) reductase (nirS and norCB, respectively) in the ΔmucA mutant in contrast to extremely low levels in the A-NO2--sensitive mucA22 mutant. Proteins that were S-nitrosylated by NO derived from A-NO2- reduction in the sensitive mucA22 strain were those involved in anaerobic respiration (NirQ, NirS), pyruvate fermentation (UspK), global gene regulation (Vfr), the TCA cycle (succinate dehydrogenase, SdhB) and several double mutants were even more sensitive to A-NO2-. Bioinformatic-based data point to future studies designed to elucidate potential cellular binding partners for MucA and MucA22. Given that A-NO2- is a potentially viable treatment strategy to combat PA and other infections, this study offers novel developments as to how clinicians might better treat problematic PA infections in COPD and CF airway diseases.


Assuntos
Proteínas de Bactérias/genética , Biofilmes , Pulmão/microbiologia , Mutação , Nitritos/farmacologia , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/fisiologia , Proteínas de Bactérias/metabolismo , Biofilmes/efeitos dos fármacos , Doença Crônica , Humanos , Concentração de Íons de Hidrogênio , Plâncton/metabolismo , Plâncton/fisiologia , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/metabolismo
4.
Nitric Oxide ; 85: 35-43, 2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-30716418

RESUMO

Hypertension is a multifactorial disease associated with impaired nitric oxide (NO) production and bioavailability. In this respect, restoring NO activity by using nitrite and nitrate has been considered a potential therapeutic strategy to treat hypertension. This possibility is justified by the understanding that both nitrite and nitrate may be recycled back to NO and also promote the generation of other bioactive species. This process involves a complex biological circuit known as the enterosalivary cycle of nitrate, where this anion is actively taken up by the salivary glands and converted to nitrite by nitrate-reducing bacteria in the oral cavity. Nitrite is then ingested and reduced to NO and other nitroso species under the acid conditions of the stomach, whereas reminiscent nitrite that escapes gastric reduction is absorbed systemically and can be converted into NO by nitrite-reductases in tissues. While there is no doubt that nitrite and nitrate exert antihypertensive effects, several agents can impair the blood pressure responses to these anions by disrupting the enterosalivary cycle of nitrate. These agents include dietary and smoking-derived thiocyanate, antiseptic mouthwash, proton pump inhibitors, ascorbate at high concentrations, and xanthine oxidoreductase inhibitors. In this article, we provide an overview of the physiological aspects of nitrite and nitrate bioactivation and the therapeutic potential of these anions in hypertension. We also discuss mechanisms by which agents counteracting the antihypertensive responses to nitrite and nitrate mediate their effects. These critical aspects should be taken into consideration when suggesting nitrate or nitrite-based therapies to patients.


Assuntos
Pressão Sanguínea/efeitos dos fármacos , Nitratos/farmacologia , Nitritos/farmacologia , Humanos , Hipertensão/tratamento farmacológico , Nitratos/metabolismo , Nitritos/metabolismo
5.
Nitric Oxide ; 86: 38-47, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-30790696

RESUMO

This work investigates how the luminescent ruthenium-nitrite complexes cis-[Ru(py-bodipy)(dcbpy)2(NO2)](PF6) (I) and cis-[Ru(py-bodipy)(dcbpy-aminopropyl-ß-lactose)2(NO2)](PF6) (II) behave toward the melanoma cancer cell line B16F10. The chemical structure and purity of the synthesized complexes were analyzed by UV-Visible and FTIR spectroscopy, MALDI, HPLC, and 1H NMR. Spectrofluorescence helped to determine the fluorescence quantum yields and lifetimes of each of these complexes. In vitro MTT cell viability assay on B16F10 cancer cells revealed that the complexes possibly have a tumoricidal role. The metal-nitrite complexes evidenced the dichotomous NO nature: at high concentration, NO exerted a tumoricidal effect, whereas cancer cells grew at low NO concentration. Flow cytometry or fluorescence microscopy aided cellular uptake calculation. Cell staining followed by fluorescence microscopy associated with organelle markers such as DAPI and Rhodamine 123 detected preferential intracellular localization of the ruthenium-nitrite py-bodipy and aminopropyl lactose derivative ruthenium complex in mitochondria. Thus, the cytotoxicity of compounds (I) and (II) against B16F10 cancer cell line show concentration-dependent results. The present studies suggest that nitric oxide ruthenium derivative compounds could be new potential chemotherapeutic agents against cytotoxic cells.


Assuntos
Antineoplásicos/farmacologia , Complexos de Coordenação/farmacologia , Lactose/análogos & derivados , Lactose/farmacologia , Doadores de Óxido Nítrico/farmacologia , Nitritos/farmacologia , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Relação Dose-Resposta a Droga , Fluorescência , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/química , Corantes Fluorescentes/farmacologia , Lactose/síntese química , Ligantes , Camundongos , Microscopia Confocal/métodos , Microscopia de Fluorescência/métodos , Mitocôndrias/metabolismo , Doadores de Óxido Nítrico/síntese química , Doadores de Óxido Nítrico/química , Nitritos/síntese química , Nitritos/química , Rutênio/química , Nanomedicina Teranóstica/métodos
6.
J Dairy Sci ; 102(3): 2207-2216, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30638997

RESUMO

Nitrates have been fed to ruminants, including dairy cows, as an electron sink to mitigate CH4 emissions. In the NO3- reduction process, NO2- can accumulate, which could directly inhibit methanogens and some bacteria. However, little information is available on eukaryotic microbes in the rumen. Protozoa were hypothesized to enhance nitrate reductase but also have more circling swimming behavior, and the yeast Saccharomyces cerevisiae was hypothesized to lessen NO2- accumulation. In the first experiment, a culture of S. cerevisiae strain 1026 was evaluated under 3 growth phases: aerobic, anoxic, or transition to anoxic culture. Each phase was evaluated with a control or 1 of 3 isonitrogenous doses, including NO3-, NO2-, or NH4+ replacing peptone in the medium. Gas head phase, NO3-, or NH4+ did not influence culture growth, but increasing NO2- concentration increasingly inhibited yeast growth. In experiment 2, rumen fluid was harvested and incubated for 3 h in 2 concentrations of NO3-, NO2-, or sodium nitroprusside before assessing chemotaxis of protozoa toward glucose or peptides. Increasing NO2- concentration decreased chemotaxis by isotrichids toward glucose or peptides and decreased chemotaxis by entodiniomorphids but only toward peptides. Live yeast culture was inhibited dose-responsively by NO2- and does not seem to be a viable mechanism to prevent NO2- accumulation in the rumen, whereas a role for protozoal nitrate reductase and NO2- influencing signal transduction requires further research.


Assuntos
Ração Animal , Bovinos , Dieta/veterinária , Nitratos/farmacologia , Rúmen/microbiologia , Animais , Quimiotaxia/efeitos dos fármacos , Cilióforos/metabolismo , Suplementos Nutricionais , Feminino , Glucose/metabolismo , Nitritos/farmacologia , Rúmen/efeitos dos fármacos , Saccharomyces cerevisiae/crescimento & desenvolvimento
7.
Free Radic Biol Med ; 131: 50-58, 2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-30500421

RESUMO

Mycobacterium tuberculosis (Mtb) survives under oxidatively and nitosatively hostile niches inside host phagocytes. In other bacteria, adaptation to these stresses is dependent upon the redox sensitive two component systems (e.g., ArcAB) and transcription factors (e.g., FNR/SoxR). However, these factors are absent in Mtb. Therefore, it is not completely understood how Mtb maintains survival and redox balance in response to reactive oxygen species (ROS) and reactive nitrogen species (RNS). Here, we present evidences that a 4Fe-4S-cofactor containing redox-sensitive transcription factor (WhiB3) is exploited by Mtb to adapt under ROS and RNS stress. We show that MtbΔwhiB3 is acutely sensitive to oxidants and to nitrosative agents. Using a genetic biosensor of cytoplasmic redox state (Mrx1-roGFP2) of Mtb, we show that WhiB3 facilitates recovery from ROS (cumene hydroperoxide and hydrogen peroxide) and RNS (acidified nitrite and peroxynitrite). Also, MtbΔwhiB3 displayed reduced survival inside RAW 264.7 macrophages. Consistent with the role of WhiB3 in modulating host-pathogen interaction, we discovered that WhiB3 coordinates the formation of early human granulomas during interaction of Mtb with human peripheral blood mononuclear cells (PBMCs). Altogether, our study provides empirical proof that WhiB3 is required to mitigate redox stress induced by ROS and RNS, which may be important to activate host/bacterial pathways required for the granuloma development and maintenance.


Assuntos
Regulação Bacteriana da Expressão Gênica , Interações Hospedeiro-Patógeno/genética , Proteínas com Ferro-Enxofre/genética , Mycobacterium tuberculosis/genética , Fatores de Transcrição/genética , Animais , Derivados de Benzeno/farmacologia , Técnicas Biossensoriais , Deleção de Genes , Homeostase/genética , Humanos , Peróxido de Hidrogênio/farmacologia , Proteínas com Ferro-Enxofre/deficiência , Leucócitos Mononucleares/efeitos dos fármacos , Leucócitos Mononucleares/metabolismo , Leucócitos Mononucleares/microbiologia , Camundongos , Viabilidade Microbiana , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/metabolismo , Nitritos/farmacologia , Oxirredução , Ácido Peroxinitroso/farmacologia , Células RAW 264.7 , Espécies Reativas de Nitrogênio/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Fatores de Transcrição/deficiência , Transcrição Genética
8.
Free Radic Biol Med ; 130: 234-243, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30399409

RESUMO

Hypertension is associated with cardiovascular remodeling. Given that impaired redox state activates matrix metalloproteinase (MMP)- 2 and promotes vascular remodeling, we hypothesized that nitrite treatment at a non-antihypertensive dose exerts antioxidant effects and attenuates both MMP-2 activation and vascular remodeling of hypertension. We examined the effects of oral sodium nitrite at antihypertensive (15 mg/kg) or non-antihypertensive (1 mg/kg) daily dose in hypertensive rats (two kidney, one clip; 2K1C model). Sham-operated and 2K1C hypertensive rats received vehicle or nitrite by gavage for four weeks. Systolic blood pressure decreased only in hypertensive rats treated with nitrite 15 mg/Kg/day. Both low and high nitrite doses decreased 2K1C-induced vascular remodeling assessed by measuring aortic cross-sectional area, media/lumen ratio, and number of vascular smooth muscle cells/aortic length. Both low and high nitrite doses decreased 2K1C-induced vascular oxidative stress assessed in situ with the fluorescent dye DHE and with the lucigenin chemiluminescence assay. Vascular MMP-2 expression and activity were assessed by gel zymography, Western blot, and in situ zymography increased with hypertension. While MMP-2 levels did not change in response to both doses of nitrite, both doses completely prevented hypertension-induced increases in vascular MMP activity. Moreover, incubation of aortas from hypertensive rats with nitrite at 1-20 µmol/L reduced gelatinolytic activity by 20-30%. This effect was fully inhibited by the xanthine oxidase (XOR) inhibitor febuxostat, suggesting XOR-mediated generation of nitric oxide (NO) from nitrite as a mechanism explaining the responses to nitrite. In vitro incubation of aortic extracts with nitrite 20 µmol/L did not affect MMP-2 activity. These results show that nitrite reverses the vascular structural alterations of hypertension, independently of anti-hypertensive effects. This response is mediated, at least in part, by XOR and is attributable to antioxidant effects of nitrite blunting vascular MMP-2 activation. Our findings suggest nitrite therapy to reverse structural alterations of hypertension.


Assuntos
Hipertensão Renovascular/tratamento farmacológico , Metaloproteinase 2 da Matriz/genética , Nitritos/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Animais , Anti-Hipertensivos/farmacologia , Antioxidantes , Aorta/efeitos dos fármacos , Aorta/patologia , Pressão Sanguínea/efeitos dos fármacos , Modelos Animais de Doenças , Febuxostat/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Hipertensão Renovascular/genética , Hipertensão Renovascular/patologia , Músculo Liso Vascular/efeitos dos fármacos , Óxido Nítrico/metabolismo , Ratos , Espécies Reativas de Oxigênio , Remodelação Vascular/efeitos dos fármacos , Xantina Oxidase/antagonistas & inibidores , Xantina Oxidase/genética
9.
Environ Sci Pollut Res Int ; 26(5): 4777-4790, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30565114

RESUMO

The denitrifying anaerobic methane oxidation (DAMO) process can achieve methane oxidation and denitrification at the same time by using nitrate or nitrite as an electron acceptor. The short- and long-term effects of nitrite on DAMO organisms were studied from macro (such as denitrification) to micro (such as microbial structure and community) based on two types of DAMO microbial systems. The results showed that the inhibitory effects of nitrite on the two DAMO microbial systems increased with rising concentration and prolonged time. In the short-term inhibitory phase, nitrite with concentrations below 100 mg N L-1 did not inhibit the two distinct DAMO enrichments. When nitrite concentration was increased to 950 mg N L-1, the nitrogen removal performance was completely inhibited. However, in the long-term inhibition experiment, when nitrite concentration was increased to 650 mg N L-1, the nitrogen removal performance was completely inhibited. In addition, in acidic conditions, the real inhibitor of nitrite is FNA (free nitrous acid), while in alkaline conditions, the real inhibitor is the ionized form of nitrite. By using high-throughput sequencing technology, the species abundance and diversity of the two DAMO microbial systems showed an apparent decrease after long-term inhibition, and the community structure also changed significantly. For the enrichment culture dominated by DAMO bacteria, the substantial drop of Methylomonas may be the internal cause of the decreased nitrogen removal rate, and for the coexistence system that hosted both DAMO bacteria and archaea, the reduction of Nitrospirae may be an internal reason for the decline of the denitrification rate.


Assuntos
Reatores Biológicos/microbiologia , Metano/metabolismo , Methylococcaceae/metabolismo , Nitritos/metabolismo , Anaerobiose/efeitos dos fármacos , Archaea/genética , Archaea/metabolismo , Desnitrificação , Sequenciamento de Nucleotídeos em Larga Escala , Methylococcaceae/efeitos dos fármacos , Methylococcaceae/genética , Methylomonas/metabolismo , Consórcios Microbianos/fisiologia , Nitratos/metabolismo , Nitratos/farmacologia , Nitritos/farmacologia , Nitrogênio/metabolismo , Oxirredução , Eliminação de Resíduos Líquidos/instrumentação , Eliminação de Resíduos Líquidos/métodos
10.
Proc Natl Acad Sci U S A ; 116(1): 217-226, 2019 01 02.
Artigo em Inglês | MEDLINE | ID: mdl-30559212

RESUMO

Advanced age and unhealthy dietary habits contribute to the increasing incidence of obesity and type 2 diabetes. These metabolic disorders, which are often accompanied by oxidative stress and compromised nitric oxide (NO) signaling, increase the risk of adverse cardiovascular complications and development of fatty liver disease. Here, we investigated the therapeutic effects of dietary nitrate, which is found in high levels in green leafy vegetables, on liver steatosis associated with metabolic syndrome. Dietary nitrate fuels a nitrate-nitrite-NO signaling pathway, which prevented many features of metabolic syndrome and liver steatosis that developed in mice fed a high-fat diet, with or without combination with an inhibitor of NOS (l-NAME). These favorable effects of nitrate were absent in germ-free mice, demonstrating the central importance of host microbiota in bioactivation of nitrate. In a human liver cell line (HepG2) and in a validated hepatic 3D model with primary human hepatocyte spheroids, nitrite treatment reduced the degree of metabolically induced steatosis (i.e., high glucose, insulin, and free fatty acids), as well as drug-induced steatosis (i.e., amiodarone). Mechanistically, the salutary metabolic effects of nitrate and nitrite can be ascribed to nitrite-derived formation of NO species and activation of soluble guanylyl cyclase, where xanthine oxidoreductase is proposed to mediate the reduction of nitrite. Boosting this nitrate-nitrite-NO pathway results in attenuation of NADPH oxidase-derived oxidative stress and stimulation of AMP-activated protein kinase and downstream signaling pathways regulating lipogenesis, fatty acid oxidation, and glucose homeostasis. These findings may have implications for novel nutrition-based preventive and therapeutic strategies against liver steatosis associated with metabolic dysfunction.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Fígado Gorduroso/prevenção & controle , NADPH Oxidases/antagonistas & inibidores , Nitratos/farmacologia , Nitritos/farmacologia , Animais , Ativação Enzimática/efeitos dos fármacos , Células Hep G2 , Hepatócitos/efeitos dos fármacos , Humanos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Nitratos/administração & dosagem , Óxido Nítrico/metabolismo , Nitritos/administração & dosagem
11.
Parasitology ; 146(2): 176-186, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30070186

RESUMO

Clonorchis sinensis (C. sinensis), a trematode parasite that invades the hypoxic hepatobiliary tract of vertebrate hosts requires a considerable amount of oxygen for its sexual reproduction and energy metabolism. However, little is known regarding the molecular mechanism of C. sinensis involved in the adaptation to the hypoxic environments. In this study, we investigated the molecular structures and induction patterns of hypoxia-inducible factor-1α (HIF-1α) and other basic helix-loop-helix and Per-Arnt-Sim (bHLH-PAS) domain-containing proteins such as HIF-1ß, single-minded protein and aryl hydrocarbon receptor, which might prompt adaptive response to hypoxia, in C. sinensis. These proteins possessed various bHLH-PAS family-specific domains. Expression of C. sinensis HIF-1α (CsHIF-1α) was highly induced in worms which were either exposed to a hypoxic condition or co-incubated with human cholangiocytes. In addition to oxygen, nitric oxide and nitrite affected the CsHIF-1α expression depending on the surrounding oxygen concentration. Treatment using a prolyl hydroxylase-domain protein inhibitor under 20%-oxygen condition resulted in an increase in the CsHIF-1α level. Conversely, the other bHLH-PAS genes were less responsive to these exogenous stimuli. We suggest that nitrite and nitric oxide, as well as oxygen, coordinately involve in the regulation of HIF-1α expression to adapt to the hypoxic host environments in C. sinensis.


Assuntos
Clonorchis sinensis/genética , Clonorchis sinensis/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Clonorquíase/complicações , Clonorquíase/parasitologia , Clonorchis sinensis/química , Clonorchis sinensis/classificação , DNA Complementar/química , Expressão Gênica , Sequências Hélice-Alça-Hélice/genética , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/química , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Conformação Molecular , Óxido Nítrico/farmacologia , Nitritos/farmacologia , Filogenia , Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/genética , Ratos , Ratos Sprague-Dawley
12.
Molecules ; 23(12)2018 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-30514001

RESUMO

We have recently discovered that the photodynamic action of many different photosensitizers (PSs) can be dramatically potentiated by addition of a solution containing a range of different inorganic salts. Most of these studies have centered around antimicrobial photodynamic inactivation that kills Gram-negative and Gram-positive bacteria in suspension. Addition of non-toxic water-soluble salts during illumination can kill up to six additional logs of bacterial cells (one million-fold improvement). The PSs investigated range from those that undergo mainly Type I photochemical mechanisms (electron transfer to produce superoxide, hydrogen peroxide, and hydroxyl radicals), such as phenothiazinium dyes, fullerenes, and titanium dioxide, to those that are mainly Type II (energy transfer to produce singlet oxygen), such as porphyrins, and Rose Bengal. At one extreme of the salts is sodium azide, that quenches singlet oxygen but can produce azide radicals (presumed to be highly reactive) via electron transfer from photoexcited phenothiazinium dyes. Potassium iodide is oxidized to molecular iodine by both Type I and Type II PSs, but may also form reactive iodine species. Potassium bromide is oxidized to hypobromite, but only by titanium dioxide photocatalysis (Type I). Potassium thiocyanate appears to require a mixture of Type I and Type II photochemistry to first produce sulfite, that can then form the sulfur trioxide radical anion. Potassium selenocyanate can react with either Type I or Type II (or indeed with other oxidizing agents) to produce the semi-stable selenocyanogen (SCN)2. Finally, sodium nitrite may react with either Type I or Type II PSs to produce peroxynitrate (again, semi-stable) that can kill bacteria and nitrate tyrosine. Many of these salts (except azide) are non-toxic, and may be clinically applicable.


Assuntos
Anti-Infecciosos/farmacologia , Fotoquimioterapia/métodos , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/farmacologia , Sais/farmacologia , Anti-Infecciosos/química , Azidas/química , Azidas/farmacologia , Brometos/química , Brometos/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Humanos , Iodetos/química , Iodetos/farmacologia , Testes de Sensibilidade Microbiana , Nitritos/química , Nitritos/farmacologia , Sais/química , Tiocianatos/química , Tiocianatos/farmacologia , Titânio/química , Titânio/farmacologia
13.
JAMA ; 320(17): 1764-1773, 2018 11 06.
Artigo em Inglês | MEDLINE | ID: mdl-30398602

RESUMO

Importance: There are few effective treatments for heart failure with preserved ejection fraction (HFpEF). Short-term administration of inorganic nitrite or nitrate preparations has been shown to enhance nitric oxide signaling, which may improve aerobic capacity in HFpEF. Objective: To determine the effect of 4 weeks' administration of inhaled, nebulized inorganic nitrite on exercise capacity in HFpEF. Design, Setting, and Participants: Multicenter, double-blind, placebo-controlled, 2-treatment, crossover trial of 105 patients with HFpEF. Participants were enrolled from July 22, 2016, to September 12, 2017, at 17 US sites, with final date of follow-up of January 2, 2018. Interventions: Inorganic nitrite or placebo administered via micronebulizer device. During each 6-week phase of the crossover study, participants received no study drug for 2 weeks (baseline/washout) followed by study drug (nitrite or placebo) at 46 mg 3 times a day for 1 week followed by 80 mg 3 times a day for 3 weeks. Main Outcomes and Measures: The primary end point was peak oxygen consumption (mL/kg/min). Secondary end points included daily activity levels assessed by accelerometry, health status as assessed by the Kansas City Cardiomyopathy Questionnaire (score range, 0-100, with higher scores reflecting better quality of life), functional class, cardiac filling pressures assessed by echocardiography, N-terminal fragment of the prohormone brain natriuretic peptide levels, other exercise indices, adverse events, and tolerability. Outcomes were assessed after treatment for 4 weeks. Results: Among 105 patients who were randomized (median age, 68 years; 56% women), 98 (93%) completed the trial. During the nitrite phase, there was no significant difference in mean peak oxygen consumption as compared with the placebo phase (13.5 vs 13.7 mL/kg/min; difference, -0.20 [95% CI, -0.56 to 0.16]; P = .27). There were no significant between-treatment phase differences in daily activity levels (5497 vs 5503 accelerometry units; difference, -15 [95% CI, -264 to 234]; P = .91), Kansas City Cardiomyopathy Questionnaire Clinical Summary Score (62.6 vs 61.9; difference, 1.1 [95% CI, -1.4 to 3.5]; P = .39), functional class (2.5 vs 2.5; difference, 0.1 [95% CI, -0.1 to 0.2]; P = .43), echocardiographic E/e' ratio (16.4 vs 16.6; difference, 0.1 [95% CI, -1.2 to 1.3]; P = .93), or N-terminal fragment of the prohormone brain natriuretic peptide levels (520 vs 533 pg/mL; difference, 11 [95% CI, -53 to 75]; P = .74). Worsening heart failure occurred in 3 participants (2.9%) during the nitrite phase and 8 (7.6%) during the placebo phase. Conclusions and Relevance: Among patients with HFpEF, administration of inhaled inorganic nitrite for 4 weeks, compared with placebo, did not result in significant improvement in exercise capacity. Trial Registration: ClinicalTrials.gov Identifier: NCT02742129.


Assuntos
Tolerância ao Exercício/efeitos dos fármacos , Insuficiência Cardíaca/tratamento farmacológico , Nitritos/uso terapêutico , Administração por Inalação , Idoso , Estudos Cross-Over , Método Duplo-Cego , Teste de Esforço , Tolerância ao Exercício/fisiologia , Feminino , Insuficiência Cardíaca/fisiopatologia , Humanos , Compostos Inorgânicos/farmacologia , Compostos Inorgânicos/uso terapêutico , Masculino , Pessoa de Meia-Idade , Nitritos/efeitos adversos , Nitritos/farmacologia , Consumo de Oxigênio , Volume Sistólico , Falha de Tratamento
14.
Chemosphere ; 211: 1137-1146, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30223329

RESUMO

Microcystin-LR (MC-LR) released by Microcystis blooms degradation usually co-exists with a chemical called nitrite, posing a serious harm to aquatic organisms. To assess the single and combined effects of MC-LR and nitrite on the reproductive endocrine system, a fully factorial experiment was designed and adult male zebrafish (Danio rerio) were exposed to 9 treatment combinations of MC-LR (0, 3, 30 µg/L) and nitrite (0, 2, 20 mg/L) for 30 d. The results showed that both MC-LR and nitrite caused concentration-dependent effects including the growth inhibition, decreased gonad index as well as testicular injuries with widen intercellular spaces and seminiferous epithelium deteriorations. And testicular pathological changes in the co-exposure groups of MC-LR and nitrite were similar but more serious than those in single-factor exposure groups. Concurrently, exposure to MC-LR or nitrite alone could significantly decrease T levels by downregulating gene expressions (gnrh2, lhß, ar, lhr) in the hypothalamic-pituitary-gonadal-liver-axis (HPGL-axis), and there were significant interactions between MC-LR and nitrite on them. In contrast, E2 levels as well as transcriptional levels of cyp19a1b, cyp19a1a and vtg1 showed significant inductions with increasing MC-LR concentrations, indicating an estrogen-like effect of MC-LR. Our findings illustrated that co-exposure of MC-LR and nitrite synergistically cause reproductive dysfunction by interfering with the HPGL axis in male fish, which prompt us to focus more on the potential risks in fish reproduction and even population dynamics due to the wide occurrence of toxic cyanobacterial blooms.


Assuntos
Disruptores Endócrinos/toxicidade , Microcistinas/toxicidade , Nitritos/farmacologia , Animais , Sinergismo Farmacológico , Sistema Endócrino/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Gônadas/efeitos dos fármacos , Masculino , Microcystis/metabolismo , Nitritos/metabolismo , Reprodução/efeitos dos fármacos , Testículo/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/crescimento & desenvolvimento , Peixe-Zebra/metabolismo
15.
Nitric Oxide ; 80: 82-88, 2018 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-30179715

RESUMO

Adequate perfusion of the placental vasculature is essential to meet the metabolic demands of fetal growth and development. Lacking neural control, local tissue metabolites, circulating and physical factors contribute significantly to blood flow regulation. Nitric oxide (NO) is a key regulator of fetoplacental vascular tone. Nitrite, previously considered an inert end-product of NO oxidation, has been shown to provide an important source of NO. Reduction of nitrite to NO may be particularly relevant in tissue when the oxygen-dependent NO synthase (NOS) activity is compromised, e.g. in hypoxia. The contribution of this pathway in the placenta is currently unknown. We hypothesised that nitrite vasodilates human placental blood vessels, with enhanced efficacy under hypoxia. Placentas were collected from uncomplicated pregnancies and the vasorelaxant effect of nitrite (10-6-5x10-3 M) was assessed using wire myography on isolated pre-constricted chorionic plate arteries (CPAs) and veins (CPVs) under normoxic (pO2 ∼5%) and hypoxic (pO2 ∼1%) conditions. The dependency on the NO-sGC-cGMP pathway and known nitrite reductase (NiR) activities was also investigated. Nitrite caused concentration-dependent vasorelaxation in both arteries and veins, and this effect was enhanced by hypoxia, significantly in CPVs (P < 0.01) and with a trend in CPAs (P = 0.054). Pre-incubation with NO scavengers (cPTIO and oxyhemoglobin) attenuated (P < 0.01 and P < 0.0001, respectively), and the sGC inhibitor ODQ completely abolished nitrite-mediated vasorelaxation, confirming the involvement of NO and sGC. Inhibition of potential NiR enzymes xanthine oxidoreductase, mitochondrial aldehyde dehydrogenase and mitochondrial bc1 complex did not attenuate vasorelaxation. This data suggests that nitrite may provide an important reservoir of NO bioactivity within the placenta to enhance blood flow when fetoplacental oxygenation is impaired, as occurring in pregnancy diseases such as pre-eclampsia and fetal growth restriction.


Assuntos
Artérias/fisiologia , Córion/irrigação sanguínea , Hipóxia/metabolismo , Nitritos/metabolismo , Veias/fisiologia , Adulto , Artérias/efeitos dos fármacos , Benzoatos/farmacologia , GMP Cíclico/metabolismo , Relação Dose-Resposta a Droga , Feminino , Humanos , Imidazóis/farmacologia , Nitritos/farmacologia , Placenta/irrigação sanguínea , Gravidez , Nitrito de Sódio/administração & dosagem , Nitrito de Sódio/farmacologia , Vasodilatação/efeitos dos fármacos , Vasodilatação/fisiologia , Veias/efeitos dos fármacos
16.
Chemosphere ; 212: 777-783, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30179842

RESUMO

The effects of co-existing nitrogen species in surface water on the phototransformation of organoarsenical p-arsanilic acid (p-ASA) have been investigated using a xenon lamp as a simulated solar light source. Significant enhancements of p-ASA phototransformation efficiency were observed in the presence of nitrate and nitrite, increasing with the concentration of these species and pH, whereas ammonia showed no obvious effect. The products, including inorganic arsenic species and organic derivatives, have been analyzed in order to reveal the phototransformation pathways. In the nitrate and nitrite systems, only small proportions of inorganic arsenic species were generated, with the majority of p-ASA being converted into other organoarsenical derivatives through hydroxylation, nitration, and nitrosation. Phototransformation of p-ASA in collected natural surface water was also observed. This work has implications for the phototransformation of p-ASA in nitrogen-contaminated surface water.


Assuntos
Ácido Arsanílico/efeitos da radiação , Nitrogênio/farmacologia , Raios Ultravioleta , Arsênico/análise , Nitratos/farmacologia , Nitritos/farmacologia , Água , Poluentes Químicos da Água/efeitos da radiação
17.
Water Sci Technol ; 77(11-12): 2812-2822, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30065133

RESUMO

High nitrite is a known operation parameter to inhibit the biological oxidation of nitrite to nitrate. The phenomenon is traditionally expressed using a Monod-type equation with non-competitive inhibition, in which the reaction associated with the biomass growth is reduced when high nitrite is present. On the other hand, very high nitrite is also known to slay nitrifiers. To clarify the difference between the growth inhibition and the poisoning, cell counting for living microorganisms in the nitrite oxidiser-enriched activated sludge was conducted in batch conditions under various nitrite concentrations together with measurements of biomass chemical oxygen demand (COD) concentration and oxygen uptake rate. The experiments demonstrated that these measureable parameters were all decayed when nitrite concentration exceeded 100-500 mgN/L at pH 7.0 in the system, indicating that nitrite poisoning took place. Biomass growth was recognised in lower range of nitrite which was expressed with growth inhibition only. Based on the response, a kinetic model for the biological nitrite oxidation was developed with a modification of IWA ASM1. The model was further utilised to calculate a possibility to wash out nitrite oxidiser in the aeration tank where a part of the return activated sludge was exposed to high nitrite liquor in a side-stream partial nitritation reactor.


Assuntos
Reatores Biológicos/microbiologia , Consórcios Microbianos/fisiologia , Nitritos/metabolismo , Esgotos/microbiologia , Eliminação de Resíduos Líquidos/instrumentação , Análise da Demanda Biológica de Oxigênio , Biomassa , Concentração de Íons de Hidrogênio , Consórcios Microbianos/efeitos dos fármacos , Nitratos/metabolismo , Nitritos/farmacologia , Oxirredução , Eliminação de Resíduos Líquidos/métodos
18.
Nitric Oxide ; 80: 70-81, 2018 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-30114530

RESUMO

Sickle cell disease (SCD) patients can have limited exercise capacity and muscle dysfunction characterized by decreased force, atrophy, microvascular abnormalities, fiber distribution changes, and skeletal muscle energetics abnormalities. Growing evidence suggests that in SCD there is alteration in nitric oxide (NO) availability/signaling and that nitrate/nitrite can serve as a NO reservoir and enhance muscle performance. Here, we examined effects of nitrite on muscle strength, exercise capacity, and on contractile properties of fast-(extensor digitorum longus, EDL) and slow-twitch (soleus) muscles in SCD mice. Compared to controls, homozygotes (sickling) had decreased grip strength, impaired wheel running performance, and decreased muscle mass of fast-twitch, but not slow-twitch muscle. Nitrite treatment yielded increases in nitrite plasma levels in controls, heterozygotes, and homozygotes but decreases in muscle nitrite levels in heterozygotes and homozygotes. Regardless of genotype, nitrite yielded increases in grip strength, which were coupled with increases in specific force in EDL, but not in soleus muscle. Further, nitrite increased EDL, but not soleus, fatigability in all genotypes. Conversely, in controls, nitrite decreased, whereas in homozygotes, it increased EDL susceptibility to contraction-induced injury. Interestingly, nitrite yielded no changes in distances ran on the running wheel. These differential effects of nitrite in fast- and slow-twitch muscles suggest that its ergogenic effects would be observed in high-intensity/short exercises as found with grip force increases but no changes on wheel running distances. Further, the differential effects of nitrite in homozygotes and control animals suggests that sickling mice, which have altered NO availability/signaling, handle nitrite differently than do control animals.


Assuntos
Anemia Falciforme/fisiopatologia , Músculo Esquelético/fisiologia , Nitritos/farmacologia , Animais , Creatina Quinase/sangue , Feminino , Masculino , Metemoglobina/análise , Metemoglobina/metabolismo , Camundongos Transgênicos , Contração Muscular/efeitos dos fármacos , Fadiga Muscular/efeitos dos fármacos , Fadiga Muscular/fisiologia , Fibras Musculares de Contração Rápida/efeitos dos fármacos , Fibras Musculares de Contração Lenta/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/lesões , Músculo Esquelético/fisiopatologia , Nitritos/sangue , Nitritos/metabolismo , alfa-Globinas/genética
19.
Meat Sci ; 145: 273-284, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30005374

RESUMO

For cured meat products, nitrite is recognized for its antimicrobial effects against pathogenic bacteria, even though the specific inhibitory mechanisms are not well known. Nitrite contributes to oxidative stress by being the precursor of peroxynitrite (ONOO-), which is the major strong oxidant. Thus, bacterial stress (highly pH-very low partial pressure of oxygen-dependent) is enhanced by the nitrate-nitrite-peroxynitrite system which is also highly pH- and low partial pressure of oxygen-dependent. Nitrite is a hurdle technology which effectiveness depends on several other hurdle technologies including sodium chloride (accelerating the autoxidation of oxymyoglobin and promote peroxynitrite formation), ascorbate (increasing ONOO- synthesis), and Aw. In this environment, certain species are more resistant than others to acidic, oxidative, and nitrative stresses. The most resistant are gram-negative aerobic/facultative anaerobic bacteria (Escherichia coli, Salmonella), and the most fragile are gram-positive anaerobic bacteria (Clostridium botulinum). This position review highlights the major chemical mechanisms involved, the active molecules and their actions on bacterial metabolisms in the meat ecosystem.


Assuntos
Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Conservação de Alimentos/métodos , Conservantes de Alimentos/farmacologia , Produtos da Carne/microbiologia , Nitratos/farmacologia , Nitritos/farmacologia , Manipulação de Alimentos , Microbiologia de Alimentos , Humanos
20.
Life Sci ; 207: 219-226, 2018 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-29898382

RESUMO

INTRODUCTION: Nitric oxide (NO) deficiency is associated with obesity and type 2 diabetes. Nitrite, a NO donor, is considered as a new therapeutic agent in diabetes. This study aims at determining effects of long-term nitrite administration on browning of white adipose tissue (WAT) in type 2 diabetic rats. METHODS: Male rats were divided into 4 groups: Control, control + nitrite, diabetes, and diabetes + nitrite. Sodium nitrite (50 mg/L in drinking water) was administered for 3 months. Body weight was measured weekly. Fasting serum levels of glucose and nitric oxide metabolites (NOx) were measured monthly. Histological evaluations and measurement of cyclic guanosine monophosphate (cGMP) and NOx levels in adipose tissue were done at the end of the study. RESULTS: Nitrite decreased serum glucose concentration and body weight gain in diabetic rats by 27.6% and 37.9%, respectively. In diabetic rats, nitrite increased NOx and cGMP levels in inguinal WAT by 95.7% and 33.1%, respectively. Numerical density in WAT of nitrite-treated diabetic rats was higher than in diabetic ones (995 ±â€¯83 vs. 2513 ±â€¯256 cell/mm3, P < 0.001); in addition, total surface area (4.84 ±â€¯0.32 vs. 44.26 ±â€¯9.7, mm2, P < 0.001) and volume of inguinal beige adipose tissue (7.2 ±â€¯0.49 vs. 66.4 ±â€¯14.51 mm3, <0.001) were higher in nitrite-treated diabetic rats compared to diabetic ones. CONCLUSIONS: Favorable effects of long-term nitrite administration in obese type 2 diabetic rats is, at least in part, due to browning of WAT and also associated with increased NOx and cGMP level in adipose tissue. These findings may have potential applications for management of diabesity.


Assuntos
Tecido Adiposo Marrom/efeitos dos fármacos , Tecido Adiposo Branco/efeitos dos fármacos , Diabetes Mellitus Tipo 2/metabolismo , Nitritos/farmacologia , Adipócitos/citologia , Adipócitos/metabolismo , Tecido Adiposo Marrom/fisiologia , Tecido Adiposo Branco/fisiologia , Animais , Peso Corporal , GMP Cíclico/metabolismo , Diabetes Mellitus Experimental/metabolismo , Modelos Animais de Doenças , Masculino , Óxido Nítrico/metabolismo , Ratos , Ratos Wistar , Fatores de Tempo
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