Production Of Nitrogen Radicals Research Articles

Innate Immune Response in Hypertension.

Even though an association between inflammation and hypertension has been known for many years, it has not been simple to ascertain the role of several physiological responses involved. The innate immune response plays a critical role in these physiological responses. Innate immune cells can be activated directly by shear stress, activate the inflammasome and produce numerous cytokines and soluble mediators essential in hypertension. NFkB activation is mainly involved in the activation of innate immune cells. Shear stress also stimulates the expression of DAMP and PAMP receptors, enhancing pathogen and danger signals and magnifying inflammation. The adaptative immune response is activated with the increased antigen presentation resulting from the insults mentioned. Chronic inflammation may lead to autoimmunity. Peripheral hypoxia, a consequence of hypertension, activates hypoxia-inducing factors 1-α and 1-β (HIF-1α, HIF-1β), which modulate innate immune cells and promote inflammation. HIF-1α is involved in the upregulation of oxygen and nitrogen radical production proteins. HIF-1β down-regulates antioxidant enzymes. However, the critical evidence of the role of innate immune cells in hypertension came from the results of clinical trials involving therapies blocking inflammatory cytokines and Toll-like receptor expression. Several lines of research have been conducted on this complex disease. Pro-tolerogenic innate immune cells, myeloid suppressor cells, and M2 macrophages may play a crucial role in promoting or resolving inflammation, cardiovascular diseases and hypertension, and should be studied in detail.

The Effect of TiO2 Catalyst on the NO Reduction by Barrier Discharge in Nitrogen

The study investigated NO reduction by N radicals produced by barrier discharge in nitrogen and the possible effect of TiO2 catalyst on this reaction. The experiments for NO reduction were carried out at temperatures ranging from room temperature to 140 °C and at NO concentrations ranging from 200 to 800 ppm. The experimental results were described by a model which was based on six main reactions for the calculation of the NO and NO2 concentrations. The analysis of model suggested two simple methods for the estimation of nitrogen radical production efficiency which in present study was 2 ppm/(J/L). The model also confirmed that N radicals are used very efficiently in the reduction of NO and this process can’t be improved by the catalyst. Nonetheless, experiments showed that the presence of TiO2 catalyst improved the removal of NO. The experimental results can be explained by surface processes taking place with NO2 with the help of other plasma produced nitrogen species.

Radical production efficiency and electrical characteristics of a coplanar barrier discharge built by multilayer ceramic technology

The present study investigated the electrical characteristics and radical production efficiency of a coplanar barrier discharge (CBD) device manufactured by Kyocera by multilayer ceramic technology. The device consisted of a number of linear electrodes with electrode and gap widths of 0.75 mm, immersed into a ceramic dielectric barrier. A closed flow-through system necessary for the measurements was prepared by placing a quartz plate at a height of 3 mm from the ceramic barrier. The production of nitrogen radicals was determined from the removal of a trace amount of NO in pure N2 gas, while the production of oxygen radicals was determined by ozone production in pure O2 or synthetic air. The production efficiency of N and O radicals and NO oxidation in synthetic air was comparable with the efficiency of a volume barrier discharge device. The power density per unit of surface area of the CBD device was more than two times larger than that of a similar volume barrier discharge setup, which makes the CBD device a compact alternative for gas treatment. The production of ozone and different nitrogen oxides was also evaluated for the open system of the CBD which is usable for surface treatment. The ozone concentration of this system was nearly independent from the input power, while the concentration of nitrogen oxides increased with input power. The open system of the CBD was additionally tested for the treatment of a silicon surface. An increase of applied power decreased the time required to reduce the water contact angle below 10 degrees but also started to have an impact on the surface roughness.

Carp Il10 Has Anti-Inflammatory Activities on Phagocytes, Promotes Proliferation of Memory T Cells, and Regulates B Cell Differentiation and Antibody Secretion.

In the current study, we investigated the effects of carp Il10 on phagocytes and lymphocytes. Carp Il10 shares several prototypical inhibitory activities on phagocytes with mammalian IL-10, including deactivation of neutrophils and macrophages, as shown by inhibition of oxygen and nitrogen radical production, as well as reduced expression of proinflammatory genes and mhc genes involved in Ag presentation. Similar to mammalian IL-10, carp Il10 acts through a signaling pathway involving phosphorylation of Stat3, ultimately leading to the early upregulation of socs3 expression. To our knowledge, this is the first study of the effects of Il10 on lymphocytes in fish. Although Il10 did not affect survival and proliferation of T cells from naive animals, it greatly promoted survival and proliferation of T cells in cultures from immunized animals, but only when used in combination with the immunizing Ag. Preliminary gene expression analysis suggests that, under these circumstances, carp Il10 stimulates a subset of CD8+ memory T cells while downregulating CD4+ memory Th1 and Th2 responses. In addition to the regulatory effect on T cells, carp Il10 stimulates proliferation, differentiation, and Ab secretion by IgM+ B cells. Overall, carp Il10 shares several prototypical activities with mammalian IL-10, including downregulation of the inflammatory response of phagocytes, stimulation of proliferation of subsets of memory T lymphocytes, and proliferation, differentiation, and Ab secretion by IgM+ B lymphocytes. To our knowledge, this is the first comprehensive analysis of biological activities of fish Il10 on both phagocytes and lymphocytes showing functional conservation of several properties of Il10.

An immune-enriched oligo-microarray analysis of gene expression in Manila clam (Venerupis philippinarum) haemocytes after a Perkinsus olseni challenge

Parasites of the genus Perkinsus cause high mortality and economic losses in bivalves commonly produced in global aquaculture. Although the immune responses of oysters and clams naturally infected with Perkinsus marinus or Perkinsus olseni have been extensively studied, there is not much information on host response at the early stages of infection. In this study, we analysed how P. olseni influences the gene expression profiles of haemocytes from the Manila clam (Venerupis philippinarum) using temporal experimental infections and an immune-enriched microarray. We identified an early phase of infection that was characterised by no mortality and by the increased expression of genes associated with pathogen recognition, production of nitrogen radicals and antimicrobial activity. Cellular processes such as inhibition of serine proteases and proliferation were also involved in this early response. This phase was followed by an intermediate stage, when the pathogen was most likely multiplying and infecting new areas of the body, and animals began to die. In this stage, many genes related to cell movement were over-expressed. Thirty days after infection metabolic pathway genes were the most affected. Apoptosis appears to be important during pathogenesis. Our results provide novel observations of the broader innate immune response triggered by P. olseni at different infection stages.

The chemistry of daytime sprite streamers – a model study

Abstract. The chemical processes in daytime sprite streamers in the altitude range of 30–54 km are investigated by means of a detailed ion–neutral chemistry model (without consideration of transport). The focus lies on nitrogen, hydrogen and oxygen species, and in particular on ozone perturbations. Initial effects of the breakdown electric fields at the tip of sprite streamers include a short-term loss of ozone due to ion–chemical reactions, a production of nitrogen radicals, and a liberation of atomic oxygen. The latter leads to a formation of ozone. In terms of relative ozone change, this effect decreases with altitude. The model results indicate that the subsequent ozone perturbations due to daytime sprites streamers differ considerably from the ones of night-time events. For night-time conditions, reactive nitrogen produced at the streamer heads is rapidly converted into significantly less reactive NO2, and there is basically no ozone depletion. The situation is different for daytime conditions where NOx causes catalytic ozone destruction. As a consequence, there is significant ozone loss in sprite streamers in the daytime atmosphere, in particular at higher altitudes. At an altitude of 54 km, ozone in the streamer column has decreased by about 15% fifteen minutes after the sprite event.

Numerical simulation for production of O and N radicals in an atmospheric-pressure streamer discharge

A streamer discharge model is developed to analyse the characteristics of a pulsed positive streamer discharge in point-to-plane electrodes filled with oxygen–nitrogen mixed gas at room temperature and atmospheric pressure. In this paper we study the mechanisms of O and N radical production in an atmospheric-pressure streamer discharge. To confirm the validity of the simulation model, the discharge emission of light and the discharge current are compared with experimental data at several voltages in gas mixtures with 2–20% oxygen concentrations. The calculated streak picture and the axial distribution of streamer luminous intensity are in good agreement with our previous experimental results. After demonstrating the reliability of the model, we performed a numerical study on radical production by the streamer discharge. The experimentally obtained axial distributions of oxygen radical production in O2(20%)/N2 and nitrogen radical production in O2(2%)/N2 are successfully reproduced in our simulation. For the production of nitrogen radicals, two-step dissociation through the vibrationally excited states is predominant.

Nodavirus encephalopathy in turbot ( Scophthalmus maximus): Inflammation, nitric oxide production and effect of anti-inflammatory compounds

Nodaviruses are the etiological agents of one of the most serious viral diseases affecting marine fish aquaculture. Nodavirus infection produces an abnormal swimming behaviour and causes encephalopathy and retinopathy associated to important mortalities. The expression of TNF-α, IRF-1 and Mx was increased in turbot after nodavirus infection. A significant increase in the production of nitrogen radicals was also observed in experimentally infected turbot. Several anti-inflammatory compounds (the antioxidant N-acetylcysteine, cortisone, dexamethasone, prednisolone and aminoguanidine) were assayed to determine the role of inflammation on nodavirus infection. Cortisone and aminoguanidine were able to accelerate the mortality onset associated to nodavirus infection, modulating the gene expression of TNF-α and, in addition, modifying the arrival time of nodavirus to the brain. These results suggest the importance of early inflammatory processes to overcome the infection.

Interplay of Pneumococcal Hydrogen Peroxide and Host-Derived Nitric Oxide

Reactive oxygen and nitrogen species are released by immune-competent cells and contribute to cellular damage. On the other hand, certain pathogens, including Streptococcus pneumoniae, are known to produce hydrogen peroxide (H2O2), while production of nitrogen radicals by bacteria presumably occurs but has been poorly studied. We determined the relative contributions of bacterial versus host-derived oxygen and nitrogen radicals to cellular damage in pneumococcal infection. A special focus was placed on peroxynitrite as a hypothetical common product formed by the reaction of H2O2 and NO. In microglial cultures, reduction of the formation of 3-nitrotyrosine and cellular damage required H2O2-deficient (DeltaspxB or DeltacarB) pneumococci and inhibition of host NO synthesis with aminoguanidine. In infected C57BL/6 mice, neuronal loss and immunopositivity for nitrotyrosine in the dentate gyrus were markedly reduced with DeltaspxB or DeltacarB bacterial mutants and in inducible nitric oxide synthase knockout mice. We conclude that although host and bacteria both produce oxygen and nitrogen radicals, the interplay of prokaryotic H2O2 and eukaryotic NO is a major contributor to cellular damage in pneumococcal meningitis.

Control of nitrogen flux for growth of cubic GaN on 3C-SiC/Si by RF-MBE

The enhancement of the production rate of nitrogen radical from a radio frequency (RF) discharge plasma is reported through the application of a DC magnetic field under RF-ECR (electron cyclotron resonance of RF) condition. High efficiency of the nitrogen radical production was realized by an optimum magnetic field for the resonance of about 0.5 mT for the electron energy of 2 eV for the 13.56-MHz discharge. The effect of controlling the divergence of the nitrogen radical flux by changing the orifice dimension was studied by measuring the color change of interference due to the film thickness. The aspect ratio of the orifice hole and the distribution of hole position determined the flux diversity. Combinatorial methodology, which realizes various III/V flux ratio without substrate rotation due to non-uniform flux, was used to study the effect of the III/V flux ratio to poly-type formation by photoluminescence. The cubic phase was grown under a stoichiometric condition of slightly Ga-rich side, with an III/V ratio of about one.

The role of iron in infections with intracellular bacteria

The requirement for iron as a critical component for cellular processes has long been appreciated. During infection with intracellular bacteria, iron is required by both the host cell and the pathogen that inhabits the host cell. Macrophages require iron as a cofactor for the execution of important antimicrobial effector mechanisms, including the NADPH dependent oxidative burst and the production of nitrogen radicals catalysed by the inducible nitric oxide synthase. On the other side of the equation, intracellular bacteria such as Salmonella typhimurium and Mycobacterium tuberculosis have an obligate requirement for iron to support their growth and survival inside cells. This brief report summarises the background to our work on iron modulation in infections with these two organisms and highlights key observations on how modulation of host iron status disturbs the equilibrium between host and pathogen and can determine the outcome of infection.