Concentrations Of Reactive Nitrogen Species Research Articles

High reactivity and bactericidal effects of plasma‐activated mist from hydrogen peroxide solution

AbstractHydrogen peroxide solutions are often utilized in logistics sterilization by misting, although their sterilizing capacity is diminished. To meet the high‐efficient and long‐term sterilization requirements of logistics, the reactivity and bactericidal efficiency are improved with plasma‐activated H2O2 solutions mist (PAHM). PAHM promotes an approximately double increase in the concentration of reactive nitrogen species, four times increase in the O3 concentration, and 36.2 times increase in H2O2 compared with water mist activation. Escherichia coli and Staphylococcus aureus are selected as the model microorganisms to evaluate the bactericidal activity. Results show that PAHM can reduce the numbers of both bacteria by two orders of magnitude after 3 min of treatment, similar to inactivated H2O2 for 10 min of treatment.

A comparative study of dielectric barrier discharge plasma device and plasma jet to generate plasma activated water and post-discharge trapping of reactive species

This work shows a comparative study of a change in properties of plasma-activated water (PAW) when prepared by using two different dielectric barrier discharge (DBD) configurations named a pencil plasma jet (PPJ) and a plasma device (PD). The air plasma produced from the DBD-PPJ and DBD-PD is characterized by voltage-current characteristics, and plasma species/radicals are identified using optical emission spectroscopy. Moreover, the present work emphasizes the trapping of reactive species (O3, NOx, etc.) carried by post-discharge residual gases during PAW production. The trapping of these gases' reactive species is carried out in water, which provides a useful by-product named plasma processed water (PPW). The results revealed a higher concentration of reactive oxygen species (dissolved O3 and H2O2) and a lower concentration of reactive nitrogen species (NO3− and NO2− ions) in PAW prepared by the DBD-PPJ configuration compared to the DBD-PD configuration. The trapping of reactive species (O3 and NOx) present in post-discharge residual gases is confirmed by determining the change in physicochemical properties and reactive oxygen–nitrogen species (RONS) concentration in virgin water used as a trapping medium. The high concentration of RONS in PPW showed a high concentration of reactive species in post-discharge residual gases and vice versa. Therefore, the reduction in reactive species downstream of post-discharge residual gases is shown by a substantial decrease in the concentration of RONS and physicochemical properties of PPW. Thus, PAW and PPW (by-product) prepared in this work could be used for multiple applications such as microbial inactivation, food preservation, and agriculture.

Quantifying the concentration and penetration depth of long-lived RONS in plasma-activated water by UV absorption spectroscopy

Reactive oxygen and reactive nitrogen species (RONS) are believed to play a key role in biomedical applications, which means that RONS must reach the target tissue to produce a therapeutic effect. Existing methods (electron spin spectrometry and microplate reading) to determine the RONS concentration are not suitable for experimental real-time measurements because they require adding an indicating reagent to the plasma-treated medium, which may alter the chemical composition of the medium. In this paper, we propose a method to measure the long-lived RONS concentration in plasma-activated water (PAW) by using UV absorption spectroscopy. Based on an analysis and fit of the absorption spectra of standard solutions (H2O2, NaNO2, and NaNO3), we propose a detailed fitting procedure that allows us to calculate the concentrations of simplex H2O2, NO2−, and NO3−. The results show that the pH and the cross reactivity between RONS in PAW correlate strongly with the absorption spectra. To confirm the accuracy of the calculations, we also use a microplate reader and add chemical reagents to measure the concentrations of H2O2, NO2−, and NO3−. The results show that the concentrations calculated by the proposed fitting method are relatively accurate and that the error range is acceptable. Additionally, the time-dependent diffusion of RONS in PAW is measured and analyzed at different depths in the PAW. This fitting approach constitutes a nonintrusive approach to measure RONS at different depths in PAW.

An atmospheric pressure plasma jet operated by injecting natural air

This work proposes an atmospheric pressure plasma jet operated by the injection of natural air. The conventional plasma jet has been modified by creating a small hole in the quartz tube. The small amount of argon gas flow inside the tube creates a pressure difference with the surrounding environment. By Bernoulli's principle, natural air is forced to penetrate inside the tube to equalize this difference. The operational range of this device exists for only low argon gas flow rates of 200–600 sccm at a specified value of applied voltage. Compared to the conventional plasma jet without a hole, the concentration of reactive nitrogen species is significantly increased due to the mixing of the surrounding air. In addition, the gas temperature of the device remains close to room temperature, suggesting its strong possibility for biomedical applications. This approach can be an initiation towards the commercialization of plasma jets by using natural air.

Enhanced concentrations of reactive nitrogen species in wildfire smoke

During the summer of 2012 the Hewlett Gulch and High Park wildfires burned an area of 400 km2 northwest of Fort Collins, Colorado. These fires both came within 20 km of the Department of Atmospheric Science at Colorado State University, allowing for extensive measurements of smoke-impacted air masses over the course of several weeks. In total, smoke plumes were observed at the measurement site for approximately 125 h. During this time, measurements were made of multiple reactive nitrogen compounds, including gas phase species NH3, NOx, and HNO3, and particle phase species NO3− and NH4+, plus an additional, unspeciated reactive nitrogen component that is measured by high temperature conversion over a catalyst to NO. Concurrent measurements of CO, levoglucosan and PM2.5 served to confirm the presence of smoke at the monitoring site. Significant enhancements were observed for all of the reactive nitrogen species measured in the plumes, except for NH4+ which did not show enhancements, likely due to the fresh nature of the plume, the presence of sufficient regional ammonia to have already neutralized upwind sulfate, and the warm conditions of the summer measurement period which tend to limit ammonium nitrate formation. Excess mixing ratios for NH3 and NOx relative to excess mixing ratios of CO in the smoke plumes, ΔNH3/ΔCO (ppb/ppb) and ΔNOx/ΔCO (ppb/ppb), were determined to be 0.027 ± 0.002 and 0.0057 ± 0.0007, respectively. These ratios suggest that smoldering combustion was the dominant source of smoke during our plume interceptions. Observations from prior relevant laboratory and field measurements of reactive nitrogen species are also briefly summarized to help create a more comprehensive picture of reactive nitrogen and fire.

Baicalein protects isoproterenol induced myocardial ischemic injury in male Wistar rats by mitigating oxidative stress and inflammation.

The aim of the present study was to investigate the cardioprotective effects of baicalein, main bioactive constituent from roots of Scutellaria baicalensis and Scutellaria lateriflora, on isoproterenol (ISO) induced acute myocardial infarction model in rats and to explore the underlying mechanisms. Rats were treated with baicalein (50mg/kg and 100mg/kg) orally for 14days and on 13th and 14th day, myocardial injury was induced by ISO injection (100mg/kg, subcutaneous) at an interval of 24h. Our study showed that ISO administration resulted in significant elevations in the levels of cardiac injury biomarkers such as cardiac troponin I, creatine kinase-MB, AST and ALT. Concentrations of reactive nitrogen species and reactive oxygen species in the heart tissue increased significantly while antioxidant enzymes level declined. The levels of tissue pro-inflammatory cytokines tumor necrosis factor-α and interleukin-6 were significantly increased after ISO administration. Pretreatment with baicalein significantly reversed these alterations induced by ISO administration. Exploration of the underlying mechanisms of protective effect of baicalein pretreatment revealed that it repressed the expression of nuclear factor kappa B and restored the ISO induced elevation of pro-inflammatory cytokines, oxidative and nitrosative stress. We found that baicalein pretreatment enhanced the level of antioxidant defense enzymes like SOD, catalase and GSH. Furthermore, the present study also demonstrated cardioprotective effects of baicalein by the histopathological findings. Taken together, our findings demonstrated that baicalein pretreatment might have a potential benefit in prevention and terminating ischemic heart diseases like myocardial infarction.

Nitric Oxide Signaling in Developing Trigeminal Neurons

Aims: This study aimed to investigate the roles of neuronal (nNOS) and endothelial (eNOS) nitric oxide synthase in the nerve growth factor (NGF) response during the development of the trigeminal ganglion (TG). In addition the roles of these nitric oxide synthases following NGF withdrawal were ascertained. Finally the effects of administration of high doses of exogenous reactive nitrogen species were considered. Study Design and Methodology: Primary cultures of trigeminal sensory neurons were pharmacologically treated with reagents known to specifically modify the activity of NOS isoforms or were treated with reagents that release exogenous reactive nitrogen species In vitro. Cultures were maintained for 24 hours after treatment and the number of surviving neurons determined. In vivo determination of NOS isoform expression was carried out using immunohistochemistry. Original Research Article Doherty; JSRR, Article no. JSRR.2014.21.004 2758 Results: eNOS and nNOS are widely expressed during TG neurodevelopment as ascertained immunohistochemically. Pharmacological inhibition of these enzymes reduces the In vitro NGF survival response of E16 neurons, but only eNOS inhibition reduces E19 TG neuron survival. Both developmental stages are vulnerable to the neurotoxic effects of high levels of exogenous nitric oxide when grown with NGF but susceptibility is higher at E19. Conclusion: During the period of naturally occurring neuronal death in the trigeminal ganglion, eNOS and nNOS are required for the survival of a proportion of trigeminal sensory neurons but when this period of cell death has ended there is a switch, and only eNOS is required for the NGF survival response. Furthermore, as these neurons mature beyond the period of naturally occurring cell death, their susceptibility to damage by elevated concentrations of reactive nitrogen species increases. This implies that there may be important mechanisms found within developing neurons that confer protection from nitrosative stress that warrant further investigation.

Kinetic Analysis of Intracellular Concentrations of Reactive Nitrogen Species

Reactive nitrogen species derived from NO have been implicated in cancer and other diseases, but their intracellular concentrations are largely unknown. To estimate them under steady-state conditions representative of inflamed tissues, a kinetic model was developed that included the effects of cellular antioxidants, amino acids, proteins, and lipids. For an NO concentration of 1 microM, total peroxynitrite (Per, the sum of ONOO(-) and ONOOH), NO(2)(*), and N(2)O(3) were calculated to have concentrations in the nanomolar, picomolar, and femtomolar ranges, respectively. The concentrations of NO(2)(*) and N(2)O(3) were predicted to decrease markedly with increases in glutathione (GSH) levels, due to the scavenging of each by GSH. Although lipids accelerate the oxidation of NO by O(2) (because of the high solubility of each in hydrophobic media), lipid-phase reactions were calculated to have little effect on NO(2)(*) or N(2)O(3) concentrations. The major sources of intracellular NO(2)(*) were found to be the reaction of Per with metals and with CO(2), whereas the major sinks were its reactions with GSH and ascorbate (AH(-)). The radical-scavenging ability of GSH and AH(-) caused 3-nitrotyrosine to be the only tyrosine derivative predicted to be formed at a significant rate. The major GSH reaction product was S-nitrosoglutathione. Analytical (algebraic) expressions are provided for the concentrations of the key reactive intermediates, allowing the calculations to be extended readily.

5-nitro-γ-tocopherol increases in human plasma exposed to cigarette smoke in vitro and in vivo

We hypothesized that the high concentrations of reactive nitrogen species in cigarette smoke and the known stimulatory effects of cigarette smoke on the inflammatory immune systems would lead to the formation of 5-nitro-γ-tocopherol (NGT). In order to assess γ-tocopherol nitration, human plasma was exposed in vitro to gas phase cigarette smoke (GPCS) or air for up to 6 h. A liquid chromatography-mass spectrometry (LC-MS) method was developed to quantitate NGT. Detector response was linear from 0.1 to 3 pmol NGT, with a detection limit of 20 fmol. After a 1 h lag time, 6 h plasma exposure to GPCS depleted ∼ 75% of α-T, ∼ 60% of γ-T and increased NGT from 3 to 134 nmol/l. The increase in NGT accounted for ∼ 20% of the γ-T decrease. NGT also correlated (R 2 = 0.9043) with nitrate concentrations in GPCS-exposed plasma. The physiologic relevance of NGT was evaluated in a group of healthy humans. Smokers ( n = 15) had plasma NGT concentrations double those of nonsmokers ( n = 19), regardless of corrections using lipids or γ-T; plasma α-T and γ-T concentrations were similar between the groups. Our results show that LC-MS can be successfully used for NGT quantitation in biologic samples. Importantly, NGT in smokers' plasma suggests that cigarette smoking causes increased nitrosative stress.

Protein nitration, metabolites of reactive nitrogen species, and inflammation in lung allografts.

This study investigated nitration and chlorination of epithelial lining fluid (ELF) proteins in patients (n = 29) who had undergone lung allotransplantation. We assayed lung lavage nitrotyrosine (NT) and chlorotyrosine (CT) by HPLC. We measured NT, nitrate (NO(3)(-)), and nitrate (NO(2)(-)) in bronchoalveolar lavage fluid (BALF) and total nitrite (NO(2)(-) + NO(3)(-)) in serum of another group of lung transplant patients (n = 82). In the first group (n = 29), percent nitration of tyrosines (Tyr) (NT/total Tyr x 100) in BALF proteins was: patients, 0.01 (0.00-0.12)%; median (25th-75th% confidence interval), and control subjects 0.01 (0.00-0.02)%. CT (CT/ total Tyr x 100) occurred only in the patients' BALF: 0.01 (0. 00- 0.02)%. In the second group (n = 82), nitrotyrosine (NT) was detected by ELISA in the BALF of patients: 9 (0-41) pmol/mg pro and control subjects: 28 (26-33). Total nitrite (NO(2)(-) + NO(3)(-)) in BALF of the patients: 3.3 (1.9-5.1) microM significantly exceeded that in control subjects: 1.3 (0.8-1.3) microM; p = 0.0133. Serum nitrite also was significantly higher in patients: 37 (26-55) microM than control subjects: 19 (17-20) microM; p = 0.0037. Airway inflammation in transbronchial biopsies (B score) correlated with NT in BALF (p = 0.0369). Lung transplants have increased airway concentrations of reactive nitrogen species (RNS) metabolites. NT, a marker of peroxynitrite (ONOO(-)), is related to the degree of airway inflammation in lung transplants.