MEASUREMENTS OF REACTIVE NITROGEN SPECIES IN THE EASTERN CHINA DURING THE EXPERIMENT PEM-WEST A

Measurements of NO_x(NO+NO_2),HNO_3,particulate nitrate,and total odd nitrogen NO_y were made at Lin atmosphere regional background station during the NASA GTE/PEM-WEST A in the fall of 1991.NO_x and N were measured using chemiluminescence detectors.HNO_3 and aerosol nitrate(NO_3^-)were collected by a filter syst NO_x concentration exhibits a significant diurnal variation:maximum occurring in the evening and postsunrise w peak occurring following sunrise.Unlike NO_x,NO_y does not show distinct diurnal variations.From the ratios day/night NO_x concentration and the diurnal cycles of two kinds of weather conditions,it is clear that photochemical production of NO_x varies with solar radiation.NO_x is the major component of total odd nitro NO_y and NO_2 is the major portion of NO_x as well.The regional background concentrations of NO_x,NO_y,aerosol trate(NO_3^-)and HNO_3 range from 4.77 to 7.02 ppb,9.24 to 10.95 ppb,0.33 to 2.38 ppb and 0.31 to 0.97 ppb in a day average,respectively.In the eastern China,the biomass burning is an important local emission source of nitro species.The ratios of NO/NO_2,NO_x/NO_y,HNO_3/NO_y,NO_3^-/NO_y and HNO_3/NO_x are also discussed in paper.

Comparison of Mechanisms of N-Nitrosation and N-Nitration of Ammonia and Dimethylamine by Reactive Nitrogen Oxygen Species:A Theoretical Study

Reactive nitrogen oxygen species（RNOS） implicate damage in biological systems,especially leading to inflammation,neurodegenerative and cardiovascular diseases,and cancer by altering the functions of biomolecules through the N-nitrosation and N-nitration reactions.The mechanisms of N-nitrosation and N-nitration reactions of ammonia and dimethylamine by RNOS,i.e.,N2O3,N2O4,N2O5 and ONOOH,were investigated at the CBS-QB3 level of theory.The computational results indicate that the N-nitrosation reaction prefers a concerted mechanism,in which a H-abstraction and ON-addition occur simultaneously,whereas a stepwise mechanism（also called a free radical mechanism） is more favorable for most nitrating agents in the N-nitration reaction,where NO2 first abstracts a hydrogen atom from the nitrogen of amines and then the induced intermediate reacts with NO2 once more to form the nitration products.However,the concerted pathway is still a feasible process for some nitrating agents such as N2O5.In addition,the relationship between the structures of different RNOS and their nitrosating or nitrating abilities was also investigated.

Study on the protective effect of Tadehaginoside on the damage of endothelial cell mitochondria induced by reactive nitrogen

Objective:To investigate the protective effect of Tadehaginoside on vascular endothelial cell injury induced by reactive nitrogen.Methods:MTT colorimetry was used to detect the effect of Tadehaginoside on the survival rate of EA.hy 926 endothelial cells in the concentration range of 5~160μmol/L;1 h after pre-administration of Tadehaginoside,0.5 mM GSNO was given to damage endothelial cells.Detect the mitochondrial specific factors COX-1,ND-1 and inflammatory factor IL-1βof EA.hy 926 cells damaged by GSNO by Real time-PCR method gene intervention.At the same time,Western blot was used to detect the changes in Bax and Bcl-2 protein expression.The mitochondrial membrane potential kit(JC-1)was used to detect the change of Tadehaginoside on the mitochondrial membrane potential after GSNO induced EA.hy 926 cell injury.Results:The results of the MTT method showed that Tadehaginoside had no obvious cytotoxicity on EA.hy 926 cells in the range of 5~160μmol/L,and the optimal protective concentration of the drug was 40μmol/L.Western Blot method showed that BAX protein expression increased in a time-dependent manner after GSNO damaged EA.hy 926 cells over time,while Bcl-2 protein expression was the opposite.Real time-PCR results showed that Tadehaginoside can significantly up-regulate COX-1 gene(P<0.05),and can significantly inhibit GSNO induced ND-1(P<0.05)and IL-1βgene up-regulation(P<0.01).At the same time,the results of JC-1 showed that Tadehaginoside could significantly protect the mitochondrial membrane potential from GSNO damage.Conclusion:The GSNO damage model may induce the increase of Bax and other pro-apoptotic proteins through mitochondrial DNA damage and reduce the expression of anti-apoptotic factor Bcl-2.Tadehaginoside has a certain protective effect on endothelial cell mitochondrial damage induced by reactive nitrogen,and its mechanism is related to inhibiting the expression of ND-1 and IL-1βgenes and upregulating the expression of COX-1 genes.

Regulatory role of peroxynitrite in advanced glycation end products mediated diabetic cardiovascular complications

The Advanced Glycation End Products(AGE)binding with its receptor can increase reactive oxygen species(ROS)generation through specific signaling mediators.The effect of superoxide(O2-)and O2-mediated ROS and reactive nitrogen species depends on their concentration and location of formation.Nitric oxide(NO)has anti-inflammatory and anticoagulant properties and a vasodilation effect,but NO can be deactivated by reacting with O_(2)^(-).This reaction between NO and O2-produces the potent oxidant ONOO−.Therefore,ONOO-'s regulatory role in AGEs in diabetic cardiovascular complications must considered as a regulator of cardiovascular complications in diabetes.

Scavenging of reactive oxygen and nitrogen species with nanomaterials

Reactive oxygen and nitrogen species （RONS） are essential for normal physiological processes and play important roles in cell signaling, immunity, and tissue homeostasis. However, excess radical species are implicated in the development and augmented pathogenesis of various diseases. Several antioxidants may restore the chemical balance, but their use is limited by disappointing results of clinical trials. Nanoparticles are an attractive therapeutic alternative because they can change the biodistribution profile of antioxidants, and possess intrinsic ability to scavenge RONS. Herein, we review the types of RONS, how they are implicated in several diseases, and the types of nanoparticles with inherent antioxidant capability, their mechanisms of action, and their biological applications.

Effects of nitrogen dioxide and its acid mist on reactive oxygen species production and antioxidant enzyme activity in Arabidopsis plants

Nitrogen dioxide（NO2） is one of the most common and harmful air pollutants. To analyze the response of plants to NO2 stress, we investigated the morphological change, reactive oxygen species（ROS） production and antioxidant enzyme activity in Arabidopsis thaliana（Col-0） exposed to 1.7, 4, 8.5, and 18.8 mg/m3NO2. The results indicate that NO2 exposure affected plant growth and chlorophyll（Chl） content, and increased oxygen free radical（O2-）production rate in Arabidopsis shoots. Furthermore, NO2 elevated the levels of lipid peroxidation and protein oxidation, accompanied by the induction of antioxidant enzyme activities and change of ascorbate（As A） and glutathione（GSH） contents. Following this, we mimicked nitric acid mist under experimental conditions, and confirmed the antioxidant mechanism of the plant to the stress. Our results imply that NO2 and its acid mist caused pollution risk to plant systems. During the process, increased ROS acted as a signal to induce a defense response, and antioxidant status played an important role in plant protection against NO2/nitric acid mist-caused oxidative damage.

Injectable reactive oxygen and nitrogen species-controlling hydrogels for tissue regeneration:current status and future perspectives

The dual role of reactive oxygen and nitrogen species(RONS)in physiological and pathological processes in biological systems has been widely reported.It has been recently suggested that the regulation of RONS levels under physiological and pathological conditions is a potential therapy to promote health and treat diseases,respectively.Injectable hydrogels have been emerging as promising biomaterials for RONS-related biomedical applications owing to their excellent biocompatibility,three-dimensional and extracellular matrix-mimicking structures,tunable properties and easy functionalization.These hydrogels have been developed as advanced injectable platforms for locally generating or scavenging RONS,depending on the specific conditions of the target disease.In this review article,the design principles and mechanism by which RONS are generated/scavenged from hydrogels are outlined alongside a discussion of their in vitro and in vivo evaluations.Additionally,we highlight the advantages and recent developments of these injectable RONS-controlling hydrogels for regenerativemedicines and tissue engineering applications.

Reactive oxygen and nitrogen species regulate porcine embryo development during pre-implantation period:A mini-review

Significant porcine embryonic loss occurs during conceptus morphological elongation and attachment from d 10 to 20 of pregnancy,which directly decreases the reproductive efficiency of sows.A successful establishment of pregnancy mainly depends on the endometrium receptivity,embryo quality,and utero-placental microenvironment,which requires complex cross-talk between the conceptus and uterus.The understanding of the molecular mechanism regulating the uterine-conceptus communication during porcine conceptus elongation and attachment has developed in the past decades.Reactive oxygen and nitrogen species,which are intracellular reactive metabolites that regulate cell fate decisions and alter their biological functions,have recently reportedly been involved in porcine conceptus elongation and attachment.This mini-review will mainly focus on the recent researches about the role of reactive ox-ygen and nitrogen species in regulating porcine embryo development during the pre-implantation period.

H_2O_2-induced Leaf Cell Death and the Crosstalk of Reactive Nitric/Oxygen Species

In plants, the chloroplast is the main reactive oxygen species （ROS） producing site under high light stress. Catalase （CAT）, which decomposes hydrogen peroxide （H2O2）, is one of the controlling enzymes that maintains leaf redox homeostasis. The catalase mutants with reduced leaf catalase activity from different plant species exhibit an H2O2-induced leaf cell death phenotype. This phenotype was differently affected by light intensity or photoperiod, which may be caused by plant species, leaf redox status or growth conditions. In the rice CAT mutant nitric oxide excess 1 （noe1）, higher H2O2 levels induced the generation of nitric oxide （NO） and higher S-nitrosothiol （SNO） levels, suggesting that NO acts as an important endogenous mediator in H2O2-induced leaf cell death. As a free radical, NO could also react with other intracellular and extracellular targets and form a series of related molecules, collectively called reactive nitrogen species （RNS）. Recent studies have revealed that both RNS and ROS are important partners in plant leaf cell death. Here, we summarize the recent progress on H2O2-induced leaf cell death and the crosstalk of RNS and ROS signals in the plant hypersensitive response （HR）, leaf senescence, and other forms of leaf cell death triggered by diverse environmental conditions.

Photoactivatable nanogenerators of reactive species for cancer therapy

In recent years,reactive species-based cancer therapies have attracted tremendous attention due to their simplicity,controllability,and effectiveness.Herein,we overviewed the state-of-art advance for photo-controlled generation of highly reactive radical species with nanomaterials for cancer therapy.First,we summarized the most widely explored reactive species,such as singlet oxygen,superoxide radical anion(O2●-),nitric oxide(●NO),carbon monoxide,alkyl radicals,and their corresponding secondary reactive species generated by interaction with other biological molecules.Then,we discussed the generating mechanisms of these highly reactive species stimulated by light irradiation,followed by their anticancer effect,and the synergetic principles with other therapeutic modalities.This review might unveil the advantages of reactive species-based therapeutic methodology and encourage the pre-clinical exploration of reactive species-mediated cancer treatments.

Quality enhancement and microbial reduction of mung bean(Vigna radiata)sprouts by non-thermal plasma pretreatment of seeds

Mung bean(Vigna radiata)sprouts are widely consumed worldwide due to their high nutritional value.However,the low yield and microbial contamination of mung bean sprouts seriously reduces their economic value.This study investigates the effects of non-thermal plasma on the quality and microbial reduction of mung bean sprouts by pretreatment of seeds in water for different times(0,1,3 and 6 min).The quality results showed that short-time plasma treatment(1 and 3 min)promoted seed germination and seedling growth,whereas long-time plasma treatment(6 min)had inhibitory effects.Plasma also had a similar dose effects on the total flavonoid and phenolic contents of mung bean sprouts.The microbiological results showed that plasma treatment achieved a reduction of native microorganisms ranging from 0.54 to 7.09 log for fungi and 0.29 to 6.80 log for bacteria at 96 h incubation.Meanwhile,plasma treatment could also efficiently inactivate artificially inoculated Salmonella typhimurium(1.83–6.22 log)and yeast(0.53–3.19 log)on mung bean seeds.The results of seed coat permeability tests and scanning electron microscopy showed that plasma could damage the seed coat structure,consequently increasing the electrical conductivity of mung bean seeds.The physicochemical analysis of plasma-treated water showed that plasma generated various long-and short-lived active species[nitric oxide radicals(NO·),hydroxyl radicals(·OH),singlet oxygen(1O2),hydrogen peroxide(H_(2)O_(2)),nitrate(NO_(3)^(-)),and nitrite(NO_(2)^(-))]in water,thus the oxidizability,acidity and conductivity of plasma-treated water were all increased in a treatment timedependent manner.The result for mimicked chemical mixtures confirmed the synergistic effect of activity of H_(2)O_(2),NO_(3)^(-)and NO_(2)^(-)on bacterial inactivation and plant growth promotion.Taken together,these results imply that plasma pretreatment of mung bean seeds in water with moderate oxidizability and acidity is an effective method to improve the yield of mung bean sprouts and reduce microbial contamination.

Effect of low-temperature plasma on the degradation of omethoate residue and quality of apple and spinach

Dielectric barrier corona discharge was developed to generate low-temperature plasma(LTP) to treat apple and spinach samples contaminated with omethoate. Experimental results showed that,after 20 min exposure, the degradation rate of omethoate residue in apple and spinach was(94.55± 0.01)% and(95.55 ± 0.01)%, respectively. When the treatment time was shorter than 20 min,the contents of moisture, vitamin C and beta-carotene were not affected by LTP. Exploration of related mechanisms suggested that LTP might destroy unsaturated double bonds of omethoate and produce phosphate ion, eventually leading to omethoate destruction. It is concluded that appropriate dosage of LTP can effectively degrade omethoate residue in fruits and vegetables without affecting their quality.

Metal natural product complex Ru-procyanidins with quadruple enzymatic activity combat infections from drug-resistant bacteria

Bacterial infection hampers wound repair by impeding the healing process.Concurrently,inflammation at the wound site triggers the production of reactive oxygen species(ROS),causing oxidative stress and damage to proteins and cells.This can lead to chronic wounds,posing severe risks.Therefore,eliminating bacterial infection and reducing ROS levels are crucial for effective wound healing.Nanozymes,possessing enzyme-like catalytic activity,can convert endogenous substances into highly toxic substances,such as ROS,to combat bacteria and biofilms without inducing drug resistance.However,the current nanozyme model with single enzyme activity falls short of meeting the complex requirements of antimicrobial therapy.Thus,developing nanozymes with multiple enzymatic activities is essential.Herein,we engineered a novel metalloenzyme called Ru-procyanidin nanoparticles(Ru-PC NPs)with diverse enzymatic activities to aid wound healing and combat bacterial infections.Under acidic conditions,due to their glutathione(GSH)depletion and peroxidase(POD)-like activity,Ru-PC NPs combined with H2O2 exhibit excellent antibacterial effects.However,in a neutral environment,the Ru-PC NPs,with catalase(CAT)activity,decompose H2O2 to O2,alleviating hypoxia and ensuring a sufficient oxygen supply.Furthermore,Ru-PC NPs possess exceptional antioxidant capacity through their superior superoxide dismutase(SOD)enzyme activity,effectively scavenging excess ROS and reactive nitrogen species(RNS)in a neutral environment.This maintains the balance of the antioxidant system and prevents inflammation.Ru-PC NPs also promote the polarization of macrophages from M1 to M2,facilitating wound healing.More importantly,Ru-PC NPs show good biosafety with negligible toxicity.In vivo wound infection models have confirmed the efficacy of Ru-PC NPs in inhibiting bacterial infection and promoting wound healing.The focus of this work highlights the quadruple enzymatic activity of Ru-PC NPs and its potential to reduce inflammation and promote bacteria-infected wound healing.

Recent advances and applications of single atom catalysts based electrochemical sensors

Single atom catalysts(SACs)have attracted considerable attention due to their unique structures and excellent catalytic performance,especially in the area of catalysis science and energy conversion and storage.In recent years,SACs have emerged as a new type of sensing material for constructing electrochemical sensors(ECSs),presenting excellent sensitivity,selectivity,and stability.Herein,we review the recent advances of SACs in electrochemical sensing and discuss the status quo of current SAC-based ECSs.Specifically,the fundamentals of SAC-based ECSs are outlined,including the involved central metal atoms and various supports of SACs in this field,the detection mechanisms,and improving strategies of SAC-based ECSs.Moreover,the important applications of SAC-based ECSs are listed and classified,covering the detection of reactive oxygen and nitrogen species,environmental pollutants,disease biomarkers,and pharmaceuticals.Last,based on abundant reported cases,the current conundrums of SAC-based ECSs are summarized,and the prediction of their future developing trends is also put forward.

NIR-triggered on-site NO/ROS/RNS nanoreactor:Cascade-amplified photodynamic/photothermal therapy with local and systemic immune responses activation

Photothermal and photodynamic therapies(PTT/PDT)hold promise for localized tumor treatment,yet their full potential is hampered by limitations such as the hypoxic tumor microenvironment and inadequate systemic immune activation.Addressing these challenges,we present a novel near-infrared(NIR)-triggered RNS nanoreactor(PBNO-Ce6)to amplify the photodynamic and photothermal therapy efficacy against triple-negative breast cancer(TNBC).The designed PBNOCe6 combines sodium nitroprusside-doped Prussian Blue nanoparticles with Chlorin e6 to enable on-site RNS production through NIR-induced concurrent NO release and ROS generation.This not only enhances tumor cell eradication but also potentiates local and systemic antitumor immune responses,protecting mice from tumor rechallenge.Our in vivo evaluations revealed that treatment with PBNO-Ce6 leads to a remarkable 2.7-fold increase in cytotoxic T lymphocytes and a 62%decrease in regulatory T cells in comparison to the control PB-Ce6(Prussian Blue nanoparticles loaded with Chlorin e6),marking a substantial improvement over traditional PTT/PDT.As such,the PBNO-Ce6 nanoreactor represents a transformative approach for improving outcomes in TNBC and potentially other malignancies affected by similar barriers.

Single-atom cobalt nanozymes promote spinal cord injury recovery by anti-oxidation and neuroprotection

Oxidative stress and inflammation are central pathophysiological processes in a traumatic spinal cord injury(SCI).Antioxidant therapies that reduce the reactive oxygen and nitrogen species(RONS)overgeneration and inflammation are proved promising for improving the outcomes.However,efficient and long-lasting antioxidant therapy to eliminate multiple RONS with effective neuroprotection remains challenging.Here,a single-atom cobalt nanozyme(Co-SAzyme)with a hollow structure was reported to reduce the RONS and inflammation in the secondary injury of SCI.Among SAzymes featuring different single metal-N sites(e.g.,Mn,Fe,Co,Ni,and Cu),this Co-SAzyme showed a versatile property to eliminate hydrogen peroxide(H_(2)O_(2)),superoxide anion(O_(2)·^(-)),hydroxyl radical(·OH),nitric oxide(·NO),and peroxynitrite(ONOO^(-))that overexpressed in the early stage of SCI.The porous hollow structure also allowed the encapsulation and sustained release of minocycline for neuroprotection in synergy.In vitro results showed that the Co-SAzyme reduced the apoptosis and pro-inflammatory cytokine levels of microglial cells under oxidative stress.In addition,the Co-SAzyme combined with minocycline achieved remarkable improved functional recovery and neural repairs in the SCI-rat model.

Nanodrugs alleviate acute kidney injury: Manipulate RONS at kidney

Currently,there are no clinical drugs available to treat acute kidney injury(AKI).Given the high prevalence and high mortality rate of AKI,the development of drugs to effectively treat AKI is a huge unmet medical need and a research hotspot.Although existing evidence fully demonstrates that reactive oxygen and nitrogen species(RONS)burst at the AKI site is a major contributor to AKI progression,the heterogeneity,complexity,and unique physiological structure of the kidney make most antioxidant and anti-inflammatory small molecule drugs ineffective because of the lack of kidney targeting and side effects.Recently,nanodrugs with intrinsic kidney targeting through the control of size,shape,and surface properties have opened exciting prospects for the treatment of AKI.Many antioxidant nanodrugs have emerged to address the limitations of current AKI treatments.In this review,we systematically summarized for the first time about the emerging nanodrugs that exploit the pathological and physiological features of the kidney to overcome the limitations of traditional small-molecule drugs to achieve high AKI efficacy.First,we analyzed the pathological structural characteristics of AKI and the main pathological mechanism of AKI:hypoxia,harmful substance accumulation-induced RONS burst at the renal site despite the multifactorial initiation and heterogeneity of AKI.Subsequently,we introduced the strategies used to improve renal targeting and reviewed advances of nanodrugs for AKI:nano-RONS-sacrificial agents,antioxidant nanozymes,and nanocarriers for antioxidants and anti-inflammatory drugs.These nanodrugs have demonstrated excellent therapeutic effects,such as greatly reducing oxidative stress damage,restoring renal function,and low side effects.Finally,we discussed the challenges and future directions for translating nanodrugs into clinical AKI treatment.

Noise-induced nitrotyrosine increase and outer hair cell death in guinea pig cochlea

Background Modern research has provided new insights into the biological mechanisms of noise-induced hearing loss, and a number of studies showed the appearance of increased reactive oxygen species （ROS） and reactive nitrogen species （RNS） during and after noise exposure. This study was designed to investigate the noise exposure induced nitrotyrosine change and the mechanism of outer hair cells death in guinea pig cochlea. Method Thirty guinea pigs were used in this study. The experimental animals were either exposed for 4 hours per day to broadband noise at 122 dB SPL （A-weighted） for 2 consecutive days or perfused cochleae with 5 mg/ml of the SIN1 solutions, an exogenous NO and superoxide donor, for 30 minutes. Then the cochleae of the animals were dissected. Propidium iodide （PI）, a DNA intercalating fluorescent probe, was used to trace morphological changes in OHC nuclei. The distribution of nitrotyrosine （NT） in the organ of Corti and the cochlear lateral wall tissue from the guinea pigs were examined using fluorescence immunohistochemistry method. Whole mounts of organ of Corti were prepared. Morphological and fluorescent changes were examined under a confocal microscope. Results Either after noise exposure or after SIN1 perfusion, outer hair cells （OHCs） death with characteristics of both apoptotic and necrotic degradation appeared. Nitrotyrosine immunolabeling could be observed in the OHCs from the control animals. After noise exposure, NT immunostaining became much greater than the control animals in OHCs. The apoptotic OHC has significant increase of nitrotyrosine in and around the nucleus following noise exposure. In the normal later wall of cochleae, relatively weak nitrotyrosine immunolabeling could be observed. After noise exposure, nitrotyrosine immunoactivity became stronger in stria vascularis. Conclusion Noise exposure induced increase of nitrotyrosine production is associated with OHCs death suggesting reactive nitrogen species participation in the cochlear pathophysiology of noise-induced hearing loss.

Nitric oxide regulation of plant metabolism

Nitric oxide(NO)has emerged as an important signal molecule in plants,having myriad roles in plant devel-opment.In addition,NO also orchestrates both biotic and abiotic stress responses,during which intensive cellular metabolic reprogramming occurs.Integral to these responses is the location of NO biosynthetic and scavenging pathways in diverse cellular compartments,enabling plants to effectively organize signal transduction pathways.NO regulates plant metabolism and,in turn,metabolic pathways reciprocally regu-late NO accumulation and function.Thus,these diverse cellular processes are inextricably linked.This re-view addresses the numerous redox pathways,located in the various subcellular compartments that pro-duce NO,in addition to the mechanisms underpinning NO scavenging.We focus on how this molecular dance is integrated into the metabolic state of the cell.Within this context,a reciprocal relationship be-tween NO accumulation and metabolite production is often apparent.We also showcase cellular pathways,including those associated with nitrate reduction,that provide evidence for this integration of NO function and metabolism.Finally,we discuss the potential importance of the biochemical reactions governing NO levels in determining plant responses to a changing environment.

Redox sensor QSOX1 regulates plant immunity by targeting GSNOR to modulate ROS generation

Reactive oxygen signaling regulates numerous biological processes,including stress responses in plants.Redox sensors transduce reactive oxygen signals into cellular responses.Here,we present biochemical evidence that a plant quiescin sulfhydryl oxidase homolog(QSOX1)is a redox sensor that negatively regulates plant immunity against a bacterial pathogen.The expression level of QSOX1 is inversely correlated with pathogen-induced reactive oxygen species(ROS)accumulation.Interestingly,QSOX1 both senses and regulates ROS levels by interactingn with and mediating redox regulation of S-nitrosoglutathione reductase,which,consistent with previous findings,influences reactive nitrogen-mediated regulation of ROS generation.Collectively,our data indicate that QSOX1 is a redox sensorthat negatively regulates plant immunity by linking reactive oxygen and reactive nitrogen signaling to limit ROS production.