Nitric Oxide Concentration Research Articles

Peroxynitrite-Free Nitric Oxide-Embedded Nanoparticles Maintain Nitric Oxide Homeostasis for Effective Revascularization of Myocardial Infarcts.

Revascularization is crucial for treating myocardial infarction (MI). Nitric oxide (NO), at an appropriate concentration, is recognized as an ideal and potent pro-angiogenic factor. However, the application of NO in the treatment of MI is limited. Improper NO supplementation is harmful to revascularization because NO is converted into harmful peroxynitrite (ONOO-) in MI tissues with high reactive oxygen species (ROS) levels. We overcome these obstacles by embedding biliverdin and NO into Prussian blue (PB) nanolattices to obtain an ONOO--free NO-embedded nanomedicine (OFEN). Unlike previous NO donors, OFEN provides NO stably and spontaneously for a longer time (>7 days), which makes it possible to maintain a stable concentration of NO, suitable for angiogenesis, through dose optimization. More importantly, based on the synergy between PB and biliverdin, OFEN converts ROS into beneficial O2 and inhibits the production of ONOO- from the source. OFEN specifically targets MI tissues and achieves sustained and stable NO delivery at the MI site. OFEN effectively promotes revascularization in the MI tissue, significantly reduces myocardial death and fibrosis, and ultimately promotes the complete recovery of cardiac function. Our strategy provides a promising approach for the treatment of myocardial and other ischemic diseases.

Mandibular Advancement Devices in Obstructive Sleep Apnea and Its Effects on the Cardiovascular System: A Comprehensive Literature Review

Background: Obstructive sleep apnea syndrome (OSA) is a chronic inflammatory disease characterized by endothelial dysfunction and cardiovascular complications. Continuous positive airway pressure (CPAP) is the standard treatment, hence poor adherence has prompted interest in mandibular advancement devices (MAD) as an alternative. This comprehensive review aimed to explore the effects of MAD therapy on oxidative stress, inflammation, endothelial function, and its impact on the cardiovascular risk in OSA patients. Results: MAD therapy significantly reduces the apnea-hypopnea index (AHI), improves serum nitric oxide (NOx) concentrations, reduces oxidative stress markers, and enhances endothelial function. Animal studies indicated that MAD reduces myocardial fibrosis and attenuates inflammatory markers. While both CPAP and MADs improve endothelial function and heart rate variability, CPAP is more effective in reducing OSA severity. Nevertheless, MAD has higher compliance, contributing to its positive impact on cardiovascular function. Moreover, CPAP and MADs have similar effectiveness in reducing cardiovascular risk. Conclusions: MAD therapy is an effective alternative to CPAP, particularly for patients with mild to moderate OSA as well as those intolerant to CPAP. It offers significant improvements in endothelial function and oxidative stress. Further studies are needed to assess MAD therapy in comprehensive OSA management.

Integrated Fertilizers for Sustainable Wheat Production to Improve Food Security—A Comprehensive Review

ABSTRACTWheat is a key cereal crop that is substantial to global food security. Fertilizers are crucial in wheat production and significantly impact the yield. This review aims to evaluate the effectiveness of inorganic, organic, and integrated fertilizers in terms of sustainable wheat production and economic and environmental benefits. For this review, we thoroughly examined 133 previous research findings. The results indicate that inorganic fertilizers play a vital role in improving wheat yield. However, continuous use of inorganic fertilizers pollutes the environment, affects beneficial microorganisms in the soil, and increases the emissions of greenhouse gases, consequently decreasing crop yield. Organic fertilizers enhance soil quality, which is critical for crop growth and development. However, a high concentration of methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) are emitted from organic fertilizers, but the CO2 emission rate is less than the sequestration rate. Integrated fertilizers trade off the drawbacks of both inorganic and organic fertilizers. Integrated fertilizers decrease nitrous oxide (N2O) and ammonia (NH3) emissions and carbon loss by 11%–24%, 13%–27%, and 18%, respectively, compared to the sole use of fertilizers. From the review analysis, the highest grain yield (4855 kg ha−1) and net benefit ($2836.66) are achieved by using a combination of 75% organic and 25% inorganic fertilizers at a rate of 120 kg N ha−1. Therefore, this combination is recommended for the users. Furthermore, a site‐specific approach research is needed on integrated fertilizers that simultaneously focus on economic and environmental profits. Also, there must be a policy that supports the farmers in teaching, training, and subsidizing them to adopt integrated fertilizers for sustainable wheat production and improving food security.

Evaluation of the potential efficacy of the nitric oxide donor molsidomine for the treatment of schizophrenia.

Schizophrenia is a chronic devastating psychiatric disease characterized by a high recurrence rate. Pharmacological management of this disorder appears disappointing since it is associated with a lack of efficacy for negative symptoms and cognitive deficits, typical features of schizophrenia, and the presence of severe undesired side effects. Thus, novel molecules with high efficacy and low toxicity for the treatment of schizophrenia are urgently needed. The involvement of the gaseous molecule nitric oxide in the pathogenesis of schizophrenia is well documented since low concentrations of nitric oxide are associated with this psychiatric disease. Therefore, chemicals able to normalize nitric oxide levels, such as nitric oxide donors, might be useful for the management of this type of schizophrenia. Molsidomine is a nitric oxide donor and is under investigation as a novel antischizophrenia agent. The aim of this review is to critically evaluate the potential efficacy of this molecule for the treatment of schizophrenia.

Medium-chain fatty acid triglycerides improve feed intake and oxidative stress of finishing bulls by regulating ghrelin concentration and gastrointestinal tract microorganisms and rumen metabolites

BackgroundAs a feed additive, medium-chain fatty acids (MCFAs)/medium-chain fatty acid triglycerides (MCTs) have been used in ruminant production, but mostly added in the form of mixed esters. Studies have shown that MCTs may have a positive effect on feed intake or oxidative stress in animals, but it is unclear which MCT could play a role, and the mechanism has not been elucidated. In this study, the effects of individual MCT on growth performance, serum intake-related hormones, and oxidative stress indices in finishing bulls were investigated and further studied the effects of MCT supplementation on gastrointestinal tract bacteria and rumen fluid metabolomics.ResultsFour ruminally fistulated Yanbian cattle (bulls) were selected in 4 × 4 Latin square designs and allocated to four treatment groups: a control group (CON) fed a basal diet (total mixed ration, TMR), three groups fed a basal diet supplemented with 60 g/bull/day glycerol monocaprylin (GMC, C8), glycerol monodecanoate (GMD, C10), and glycerol monolaurate (GML, C12), respectively. Compared with the CON group, GMD tended to increase the dry matter intake (DMI) of finishing bulls (P = 0.069). Compared with the CON group, GMD significantly increased the concentration of ghrelin O-acyl transferase (GOAT), total ghrelin (TG), acylated ghrelin (AG), and orexins (P < 0.05) and significantly decreased the concentrations of hydrogen peroxide (H2O2), malondialdehyde, reactive oxygen species (ROS), and lipopolysaccharides (LPS) in the serum of finishing bulls (P < 0.05). Compared with the CON group, GMD and GML significantly increased the concentrations of total antioxidant capacity (T-AOC), catalase, glutathione peroxidase (GSH-PX), glutathione reductase (GR), and nitric oxide (NO) in the serum of finishing bulls (P < 0.05). Compared with the CON group, there were 5, 14, and 6 significantly different bacteria in the rumen digesta in the C8, C10, and C12 groups, respectively; there were 3, 10, and 5 significantly different bacteria in the rumen fluid in the C8, C10, and C12 groups, respectively; and only one differential bacteria (genus level) in the feces among the four treatment groups. Compared with the CON group, there were 3, 14, and 15 significantly differential metabolites identified under positive ionization mode in the C8, C10, and C12 groups, respectively, while under negative ionization mode were 3, 11 and 14, respectively. Correlation analysis showed that there was a significant correlation between DMI, GOAT, AG, GSH-PX, LPS, gastrointestinal tract bacteria, and rumen fluid metabolites.ConclusionsOur findings revealed that different types of MCTs have different application effects in ruminants. Among them, GMD may improve the feed intake of finishing bulls by stimulating the secretion of AG. GMD and GML may change gastrointestinal tract microorganisms and produce specific rumen metabolites to improve the oxidative stress of finishing bulls, and ghrelin may also be involved. This study enlightens the potential mechanisms by which MCT improves feed intake and oxidative stress in finishing bulls.5d9kULzJFQsQ3ajLfa--XDVideo

Ru-Incorporation-Induced Phase Transition in Co Nanoparticles for Low-Concentration Nitric Oxide Electroreduction to Ammonia at Low Potential.

Electrocatalytic reduction of nitric oxide (NO) to ammonia (NH3) represents a potential solution for improving the disrupted nitrogen cycle balance. Unfortunately, designing efficient electrocatalysts for NO reduction reaction (NORR) remains a notable challenge, especially at low concentrations. Herein, a displacement-alloying strategy is reported to successfully induce the phase transition of Co nanoparticles supported on carbon nanosheets from face-centered cubic (fcc) to hexagonal close-packed (hcp) structure through Ru incorporation. The obtained RuCo alloy with hcp phase structure (hcp-RuCo) exhibits apparent NORR activity with a record-high Faraday efficiency of 99.2% and an NH3 yield of 77.76µg h-1 mgcat -1 at -0.1V versus reversible hydrogen electrode at a NO concentration of 1vol %, surpassing Co nanoparticles with fcc phase structure and most reported catalysts. Density functional theory calculations reveal that the excellent NORR activity of hcp-RuCo can be attributed to the optimized electronic structure of Co site and lowered energy barrier of the potential rate-determining step through phase transition. Furthermore, the assembled Zn-NO battery using hcp-RuCo as the cathode achieves a power density of 2.33mW cm-2 and an NH3 yield of 45.94µg h-1 mgcat -1. This work provides a promising research perspective for low-concentration NO conversion.

Physicochemical perturbation increases nitrous oxide production from denitrification in soils and sediments

Abstract. Atmospheric concentrations of nitrous oxide (N2O), a potent greenhouse gas that is also responsible for significant stratospheric ozone depletion, have increased in response to the intensified use of agricultural fertilizers and other human activities that have accelerated nitrogen cycling processes. Microbial denitrification in soils and sediments is a major source of N2O, produced as an intermediate during the reduction of oxidized forms of nitrogen to dinitrogen gas (N2). Substrate availability (nitrate and organic matter) and environmental factors such as oxygen levels, temperature, moisture, and pH influence rates of denitrification and N2O production. Here we describe the role of physicochemical perturbation (defined here as a change from the ambient environmental conditions) in influencing rates of denitrification and N2O production. Changes in salinity, temperature, moisture, pH, and zinc in agricultural soils induced a short-term perturbation response characterized by lower rates of total denitrification and higher rates of net N2O production. The ratio of N2O to total denitrification (N2O : DNF) increased strongly with physicochemical perturbation. A salinity press experiment on tidal freshwater marsh soils revealed that increased N2O production was likely driven by transcriptional inhibition of the nitrous oxide reductase (nos) gene and that the microbial community adapted to altered salinity over a relatively short time frame (within 1 month). Perturbation appeared to confer resilience to subsequent disturbance, and denitrifiers from an environment without salinity fluctuations (tidal freshwater estuarine sediments) demonstrated a stronger N2O perturbation response than denitrifiers from environments with more variable salinity (oligohaline and mesohaline estuarine sediments), suggesting that the denitrifying community from physicochemically stable environments may have a stronger perturbation response. These findings provide a framework for improving our understanding of the dynamic nature of N2O production in soils and sediments, in which changes in physical and/or chemical conditions initiate a short-term perturbation response that promotes N2O production that moderates over time and with subsequent physicochemical perturbation.

Physiological, Performance and Perceptual Effects of Acute Intake of an L-Arginine and L-Citrulline Beverage Prior to a Repeated Bout of Intensive Running Among University Soccer Players

The purpose of this study was to determine whether a combined L-arginine and L-citrulline beverage can enhance total nitric oxide (NOx), as well as physiological (cardiopulmonary metrics) and perceptual (rate of perceived exertion) responses to a repeated bout of high-intensity exercise among university soccer players. Thirty male soccer players were included in a randomized double-blind, placebo-controlled, parallel design. Participants performed two bouts of high-intensity running, spaced two hours apart. Forty minutes before the second bout only, participants consumed a 500 mL beverage containing 6 g L-arginine and 6 g L-citrulline (n = 15) or placebo (n = 15). Blood NOx concentration was measured immediately before and after both bouts. There was no significant increase in NOx or significant interaction effects for physiological, performance, or perceptual variables between the L-arginine/L-citrulline and placebo groups. The peak volume of oxygen uptake of the L-arginine/L-citrulline group was significantly higher in the second compared with the first exercise bout (54.92 ± 4.81 vs. 50.54 ± 9.22 mL/kg/min; p = 0.01). In the second bout of exercise, time to exhaustion in the L-arginine/L-citrulline group increased by 8.5% (~60 s) compared to the first. In conclusion, these results suggest that a single dose of L-arginine/L-citrulline beverage did not increase NOx yet seemed to impact aerobic metabolism in university soccer players.

MOF nanoflowers-based flexible portable NO sensors for human airway inflammation detection

The concentration of nitric oxide (NO) in exhaled breath is linked to respiratory diseases, requiring precise detection. Traditional two-dimensional (2D) carbon-based materials used in chemiresistive gas sensors suffer from high detection limits due to a lack of functional sites, while metal oxide sensors are limited by poor selectivity and high operating temperatures, restricting their development. Recently, metal–organic frameworks (MOFs) have emerged as an effective material for NO monitoring due to their superior selectivity; however, their inherent insulating properties hinder practical use. In this study, we synthesized Ni, Co-MOF-74-Carbon Nanotube (CNT) heterostructured nanoflowers, leveraging their bimetallic active sites and large specific surface area to enhance NO adsorption. This composite material, integrated with breathable nanofibrous membranes through physical deposition, exhibits high selection to NO, achieving a linear response range of 30 to 1000 ppb at room temperature and a limit of detection (LOD) of 18.6 ppb. This sensor can accurately detect NO levels in the exhaled breath of both healthy and diseased individuals, confirming its potential for respiratory disease diagnosis. Additionally, we developed a portable device integrating the Ni, Co-MOF-74-CNT- polyacrylonitrile (PAN) membrane, a microcontroller unit (MCU), and a Bluetooth module for real-time NO detection. The systematic design and successful validation of this portable gas sensor pave the way for future home-based real-time monitoring of airway inflammation.

Role of Glutamine Synthetase on Vascular Permeability in Gliomas.

This study aimed to investigate the effect and underlying mechanism of inhibiting glutamine synthetase (GS) on the vascular permeability of gliomas. C6 glioma rat models were randomly divided into control and L-methionine sulfoximine (MSO) treatment groups. MSO was intraperitoneally injected once every other day for a total of three injections in the MSO group. We assessed the effect of MSO on tumor vascular permeability by tail vein injection of Evans blue dye. GS activity, glutamate (Glu) concentration, glutamine (Gln) concentration, and arginine concentration in tumor tissues were measured using the corresponding kits. qPCR experiments were then conducted to examine the effect of glutamate concentration on N-methyl-D-aspartate (NMDA) receptor expression. Finally, the nitric oxide synthase (NOS) assay kit and the nitric oxide (NO) assay kit were employed to detect NOS activity and NO concentration changes, respectively. Increased glioma tumor vascular permeability was observed after intraperitoneal injection of MSO; MSO acted as an inhibitor of GS, leading to a decrease in GS activity; increased glutamate levels caused activation of NMDA receptors and further activation of NOS; additionally, elevated NO levels were detected in association with an increase in arginine and NOS. Inhibiting GS results in increased vascular permeability in gliomas, which is associated with elevated NO levels and the vasodilatory effects of NO.

Administration of melatonin nanoparticles improves testicular blood flow, echotexture of testicular parenchyma, scrotal circumference, and levels of estradiol and nitric oxide in prepubertal ossimi rams under summer heat stress.

Environmental heat stress (HS) impairs reproductive efficiency in farm animals. This study investigated, for the first time, how the melatonin and melatonin nanoparticles treatment affected the testicular hemodynamics, testicular volume, echotexture [Pixel intensity (PIX) and integrated density (IND)], scrotal circumference, serum concentration of testosterone (T), estradiol (E2), nitric oxide (NO), and total antioxidant capacity (TAC) in prepubertal Ossimi ram lambs in hot climatic conditions. The lambs undergoing examination had a temperature humidity index (THI) of 87.05 ± 1.70, indicating severe HS condition. Fifteen prepubertal Ossimi ram lambs were exposed to a single s.c injection of either nano melatonin (nano melatonin group; 20mg/ram; n = 5) or melatonin suspended in two ml of corn oil (melatonin group; 40mg/ram; n = 5) or two ml of corn oil (control group; n = 5). Blood collection and ultrasonographic assessment of the testes and supratesticular arteries (STAs) were conducted immediately before treatment (W0) and once weekly for six successive weeks after nano melatonin and melatonin injection (W1-W6). Results revealed decreases (P < 0.05) in the Doppler indices (resistive index; RI and pulsatility index; PI) of the testicular arteries at most time points of the study in the nano melatonin and melatonin groups. PIX of testicular parenchyma was significantly increased (P ˂ 0.05) in the treated groups compared to the control one. IND of testicular parenchyma increased significantly in the nano melatonin group compared to the melatonin and control groups. Testicular volume and scrotal circumference significantly increased (P < 0.05) in nano melatonin and melatonin groups compared to the control one. T concentration did not significantly (P > 0.05) change in the treated groups compared to the control group. E2, NO, and TAC concentrations increased (P < 0.05) in the treated groups compared to the control one. In conclusion, this study extrapolated that administrations of melatonin or nano melatonin can ameliorate the effects of environmental HS in prepubertal Ossimi ram lambs with a more protective effect and lower dose of nano melatonin.

Nitrogen Oxide (NO) in the Pathogenesis of Preeclampsia.

The concentrations of nitric oxide (NO) donors in the plasma of pregnant women with preeclampsia is several times higher than in healthy pregnant women. Antihypertensive drugs acting not through the NO-mediated mechanisms normalized BP in some women with preeclampsia, but did not significantly reduce the levels of NO donors in the plasma. It appears that preeclampsia is associated with insufficient NO availability for the targets, rather than low intensity of NO synthesis. The concentration of NO donor molecules in the plasma can therefore be a useful additional diagnostic marker of preeclampsia.

Dual-action defense: A photothermal and controlled nitric oxide-releasing coating for preventing biofilm formation

Biofilms formed by pathogenic bacteria on biomedical devices and implants pose a considerable challenge due to their resistance to conventional treatments and their role in severe infections. Preventing biofilm formation is strategically more advantageous than attempting to eliminate the mature biofilms, particularly in addressing the persistence of such formations. In this context, a dual-action antibiofilm coating is developed, utilizing S-nitrosothiols functionalized candle soot (CS), which capitalizes on CS’s strong light absorption for photothermal therapy and the controlled release of nitric oxide (NO) from S-nitrosothiols to inhibit biofilm formation. This coating exhibits stable and efficient light-to-heat conversion, along with the ability to release NO gradually at physiological temperatures and to rapidly release NO on demand when triggered by a near-infrared (NIR) laser. Under NIR irradition, the coating generates heat swiftly and releases substantial amounts of NO, which synergistically disrupts bacterial membranes, leading to the leakage of intracellular components and the effective eradication of surface-adhered bacteria. In the absence of NIR irradiation, the coating continuously releases low concentrations of NO, which depletes exopolysaccharides and impedes biofilm formation. The antibiofilm efficacy of this coating is assessed against Staphylococcus aureus and Pseudomonas aeruginosa, demonstrating marked reductions in bacterial viability and biofilm formation in vitro. Additionally, the coating exhibits minimal cytotoxicity and can be easily applied to diverse substrates. This study underscores the potential of this coating as a broad-spectrum, non-toxic approach for preventing biofilm-related complications in biomedical applications.

Clove Aqueous Extract Alleviates Acute Kidney Injury Induced by Folic Acid in Rats

Background: Acute Kidney Injury (AKI) is a common clinical disease that has a high incidence and mortality rate. Clove, a robust natural source of bioactive chemicals and rich in secondary metabolites, plays a wide range of biological roles. Aim: The present study aimed to assess the ameliorative efficacy of clove extract against acute renal damage induced by folic acid in rats. Methods: Gas Chromatography/Mass Spectrometry (GC/MS) was used to investigate the main components of clove extract. Folic acid, at a dose of 250 mg/kg, was delivered intraperitoneally to rats to induce AKI. Eighteen rats were divided into three groups: control, AKI, and AKI + clove extract (500 mg/kg). Results: The administration of clove extract significantly restored the levels of creatine, urea, uric acid, sodium, potassium, chloride, creatinine clearance, and microalbumin to nearly normal levels. Also, clove water extract inhibited oxidative stress by decreasing concentrations of Malondialdehyde (MDA) and Nitric Oxide (NO). Furthermore, clove extract elevated the levels of Glutathionereduced (GSH), Catalase (CAT), and Glutathione S-transferase (GST). Kidney section histology showed notable improvements after the administration of clove extract. Conclusion: The clove water extract has been found to contain many bioactive components possessing antioxidant and anti-inflammatory properties, effectively protecting against acute renal injury.

Intestinal microbiome dysbiosis increases Mycobacteria pulmonary colonization in mice by regulating the Nos2-associated pathways

Increasing researches reveal gut microbiota was associated with the development of tuberculosis (TB). How to prevent or reduce Mycobacterium tuberculosis colonization in the lungs is a key measure to prevent TB. However, the data on gut microbiota preventing Mycobacterium colonization in the lungs were scarce. Here, we established the clindamycin-inducing intestinal microbiome dysbiosis and fecal microbial transplantation models in mice to identify gut microbiota’s effect on Mycobacterium’s colonization in the mouse lungs and explore its potential mechanisms. The results showed that clindamycin treatment altered the diversity and composition of the intestinal bacterial and fungal microbiome, weakened the trans-kingdom network interactions between bacteria and fungi, and induced gut microbiome dysbiosis in the mice. Gut microbiota dysbiosis increases intestinal permeability and enhances the susceptibility of Mycobacterium colonization in the lungs of mice. The potential mechanisms were gut microbiota dysbiosis altered the lung transcriptome and increased Nos2 expression through the ‘gut–lung axis’. Nos2 high expression disrupts the intracellular antimicrobial and anti-inflammatory environment by increasing the concentration of nitric oxide, decreasing the levels of reactive oxygen species and Defb1 in the cells, and promoting Mycobacteria colonization in the lungs of mice. The present study raises a potential strategy for reducing the risks of Mycobacteria infections and transmission by regulating the gut microbiome balance.

Synthesis and Biological Evaluation of Isoaurone Derivatives as Anti-inflammatory Agents.

Twenty-eight isoaurone derivatives with 1,2,4-triazole moieties were synthesized using a fragment-based design strategy, and their anti-inflammatory activity was investigated. The anti-inflammatory effect of the most active derivatives, 14e (41.82%), was dose-dependent and higher than the values for celecoxib (31.82%). Compound 14e was almost non-toxic and inhibited different concentrations of nitric oxide (NO). The western blotting results demonstrated that cyclooxygenase-2 (COX-2) expression was elevated when the macrophages were exclusively treated with LPS. However, compound 14e effectively suppressed the LPS-induced COX-2 upregulation. Subsequent investigation revealed that 14e is a promising compound capable of inhibiting the downstream signaling of COX-2. With the above interesting biological profile, molecular 14e could be a promising lead to develop novel anti-inflammatory agents.

Guidelines for anti‐inflammatory assays in RAW264.7 cells

AbstractIn recent years, research on various bioactive compounds with anti‐inflammation effects has become increasingly active. Evaluating anti‐inflammatory activity is well established in cell models represented by RAW264.7 cells. Methylthiazolyldiphenyl‐tetrazolium bromide (MTT) and cell counting kit‐8 (CCK‐8) assays are commonly used to detect the effects of drugs or deleterious substances on cytotoxicity, cell viability, and survival. RAW264.7 cells release nitric oxide (NO) when exposed to inflammatory stimuli, so their anti‐inflammatory capacity can be assessed by detecting the NO content in cell culture supernatants, and the Griess method is one of the commonly used methods for determining NO concentration. RAW264.7 cells release a variety of inflammation‐associated cytokines, such as the TNF‐α and IL‐1β, with ELISA being the standard method to detect the release of these inflammatory factors. For mRNA expression levels of genes associated with inflammation, real‐time PCR (Quantitative Real‐time PCR, qPCR) is commonly used. In addition, the well‐known western blotting assay can be used to detect the expression levels of proteins associated with inflammatory signaling pathways. In this guideline, we discuss the basic principles and practices of the above experimental methods, which provide a valuable reference for the anti‐inflammatory experimental methods in cellular models such as the RAW264.7 cells.

Calibration techniques for quantitative NO measurement using Laser-Induced Fluorescence

Laser-Induced Fluorescence (LIF) is an essential optical diagnostic technique for the high-resolution and low-uncertainty measurement of combustion species concentration in a variety of applications and conditions. Two different calibration techniques are explored in this study to obtain quantitative Nitric Oxide (NO) concentration measurements in flames. The first technique, the most employed in the literature, uses the extrapolation of the fluorescence signal from seeded to nascent NO and is only valid under negligible NO reburn conditions. The second technique uses the optical calibration of the experimental setup to relate it to a modelled LIF signal and can be applied regardless of NO reburn. Both of these techniques are explored under two different assumptions: constant and non-constant interfering LIF signal on the NO absorption spectrum. While the former is most often used in the literature, the latter is necessary when the LIF signal from interfering species cannot be distinguished from the NO-LIF signal, especially in high pressure conditions. Hence, a total of four techniques are presented in this work and are found to be in excellent agreement when performed in different flame conditions. The calibration techniques are applied to three lean, atmospheric, laminar, premixed, methane-air flames to explore their field of applicability. Specifically, the study explores the relevance of the techniques in reburn conditions, which occur mostly in high pressure, rich, highly-seeded, or NH3-containing flames. This study aims to offer the reader a portfolio of calibration techniques to use according to the conditions in which they need to be applied. While this study was carried out measuring NO concentration in a stagnation flame burner, the concepts and equations presented can be transposed to the measurement of other species and to other experimental configurations.

Amino Acid Functionalized SrTiO3 Nanoarrays with Enhanced Osseointegration Through Programmed Rapid Biofilm Elimination and Angiogenesis Controlled by NIR-Driven Gas Therapy.

Bacterial biofilm formation is closely associated with persistent infections of medical implants, which can lead to implantation failure. Additionally, the reconstruction of the vascular network is crucial for achieving efficient osseointegration. Herein, an anti-biofilm nanoplatform based on L-arginine (LA)/new indocyanine green (NICG) that is anchored to strontim titanium oxide (SrTiO3) nano-arrays on a titanium (Ti) substrate by introducing polydopamine (PDA) serving as the interlayer is designed and successfully fabricated. Near-infrared light (NIR) is used to excite NICG, generating reactive oxygen species (ROS) that react with LA to release nitric oxide (NO) molecules. Utilizing the concentration-dependent effect of NO, high power density NIR irradiation applied during the early stage after implantation to release a high concentration of NO, which synergized with the photothermal effect of PDA to eliminate bacterial biofilm. Subsequently, the irradiation power density can be finely down-regulated to reduce the NO concentration in subsequent treatment for accelerating the reconstruction of blood vessels. Meanwhile, SrTiO3 nano-arrays improve the hydrophilicity of the implant surface and slowly release strontium (Sr) ions for continuously optimizing the osteogenic microenvironment. Effective biofilm elimination and revascularization alongside the continuous optimization of the osteogenic microenvironment can significantly enhance the osseointegration of the functionalized Ti implant in in vivo animal experiments.

Impact of citrulline malate supplementation on exercise performance and muscle regeneration

Background. A world of sport is filled with various types of supplements. For many years we have been searching for ways, to improve our strength and endurance. One of them is L-citrulline, witch is an endogenous amino acid, created from carbamyl and ornithine in the urea cycle. In the organism it is converted into arginine, and used during the cycle of transition into nitric oxide (NO). This mechanism probably can be associated with enhaced blood flow into muscle tissue, what can be helpful during both resistance and high-intensity exercise performance, and also during recovery of muscular performance.Material and methods. This article comprises a literature review based on publications from: PubMed, Clinicalkey, Journal of the International Society of Sports Nutrition, The Journal of Strength and Conditioning Research, Google scholar.Results. Citrulline malate is a sports supplement. However, the evidence base for its efficacy is still insufficient to permit clear conclusions to be drawn about its action.Conclusion. The substance citrulline malate increases the concentration of nitric oxide in the organism through numerous transformations. At present, it is not possible to state unequivocally whether this effect positively improves the function and efficiency of the muscular system, or whether it increases the efficiency of blood supply to organs and muscles. However, there are a large number of indications that, with the right dosage and supplementation regimen, we will be able to fully exploit the potential of this supplement as an aid to further sporting performance.