NO Generation Research Articles

The Probiotic Streptococcus salivarius M18 Increases Plasma Nitrite but Does Not Alter Blood Pressure: A Pilot Randomised Controlled Trial

Some species of oral bacteria can reduce dietary nitrate to nitrite, which can later be converted to nitric oxide in the nitrate—nitrite—nitic oxide pathway. Increasing nitric oxide availability can reduce blood pressure (BP) and improve exercise performance. Streptococcus salivarius M18 (Streptococcus salivarius M18) is a bacteriocin-producing probiotic that is known to improve oral health by inhibiting pathogenic oral bacteria. However, it is presently unclear whether probiotic-induced alterations to the oral microbiome will influence circulating levels of nitric oxide metabolites and BP. Purpose: To determine the effects of Streptococcus salivarius M18 supplementation on plasma and salivary nitrate and nitrite levels and BP. Methods: Ten healthy males (age 32 ± 8 y, body mass 88.2 ± 15.1 kg) completed 2 × 14-day supplementation phases in a randomized order at least 14 days apart. In one phase, participants consumed Streptococcus salivarius M18 probiotic lozenges (2.5 billion colony-forming units/dose) once per day, and in the other, they ingested water (placebo). The abundance of bacteria on the tongue was assessed via Illumina 16S rRNA gene sequencing, unstimulated saliva, and venous blood samples were collected, and BP was measured pre and post each phase. Saliva and plasma were analysed for nitrate and nitrite using chemiluminescence, and pH was measured in saliva. The change in each outcome from pre- to post-supplementation was compared between phases using repeated measures ANOVA. Results: Plasma nitrite increased from baseline following probiotic supplementation (from 173 ± 39 to 223 ± 63 nM, p = 0.003, 95% CI 192–250 nM). In comparison, there was no change in the placebo phase or between baselines (all p > 0.05). The abundance of nitrite-producing bacteria was not altered, salivary nitric oxide metabolites and pH did not change, and the increase in plasma nitrite did not result in reductions in BP (all p > 0.05). Conclusions: Supplementation with Streptococcus salivarius M18 increased plasma nitrite, a key marker of NO availability. Despite this, Streptococcus salivarius M18 did not lower BP in these healthy normotensive participants. Additionally, the increase in plasma nitrite was not associated with abundance changes in bacteria thought important to NO generation. Further research is required to determine the mechanism behind the increase in plasma nitrite and the potential therapeutic and ergogenic benefits of Streptococcus salivarius M18 supplementation.

An investigation on flame structure and NOx formation in a gas turbine model combustor using large eddy simulation

In this work, large eddy simulations (LES) of a Gas Turbine Model Combustor (GTMC) are done using a five-step global mechanism that includes separate thermal and non-thermal NOx formation parts. To verify the accuracy of the solution, time-averaged profiles of the flow variables and fluctuations are compared to the available experimental and numerical data. The LES results show that the vortical structures inside the chamber are highly connected to the temperature field and chemical reactions, and despite having a major role in fast premixing and consequent NOx reductions, they contribute to NOx generation by forming high temperature spots inclusive of chemical radicals. Also, the importance of the baroclinic torque in vorticity creation is demonstrated by comparing the corresponding values to vortex stretching in upstream parts of the chamber. It is shown that the baroclinic torque mostly takes action between high vorticity and high strain regions and can possibly intensify the strong vortices, while the vortex stretching is mostly active near the strong vortices. Furthermore, observation of detailed statistics shows that most of the heat release occurs in samples with mixture fractions near the global value, while NO generation is highly biased toward the strong vortices and the stoichiometric mixture fraction. To investigate the role of the radicals in more details, a chemical reactor network (CRN) is created by clustering the LES solution. Also, the integration of Partially Stirred Reactors (PaSRs) with Perfectly Stirred Reactor (PSR) networks is used to improve the accuracy of predicting the reactant jet penetration and ignition radicals.

A brief report on eugenol oleate is an oral immunomodulatory molecule against visceral leishmaniasis

Visceral Leishmaniasis (VL) is a life-threatening infectious disease and is acclaimed as a neglected tropical disease, caused by Leishmania donovani. It leads to severe immune suppression in the host defense system. Higher cytotoxicity, rigorous side effects, and lower therapeutic indexes (TI) of current antileishmanial drugs have created a necessity to develop new molecules with better antileishmanial activity and high TI value. We synthesized a plenty number of derivatives of Eugenol and screened them for their activity against promastigote and amastigote forms of L. donovani. Among the synthesized derivatives, Eugenol oleate showed better antileishmanial activity against extracellular promastigotes (IC50- 20.13 ± 0.91 μM) and intracellular amastigotes (EC50-4.25 ± 0.26 μM). The TI value (82.24 ± 3.77) was found to improve by 10 to 13-folds compared to amphotericin B and miltefosine, respectively. Treatment with Eugenol oleate activated the PKC-βII–p38 MAPK and produced IL-12 and IFN-γ, which activated the iNOS2 to produce NO free radicals that cleared the intracellular parasite. Eugenol oleate was found safe with an appreciable pharmacokinetic profile for the oral anti-VL agent. This molecule increased the Th1 cytokine profile and decreased the Th2 cytokine profile observed from ELISA and qPCR, suggesting that the Eugenol oleate induced the parasite clearance through the activation of the host immune system. Hence, this study represented that Eugenol oleate, an oral immunomodulatory molecule, could induce a host protective immune response against visceral leishmaniasis through enhanced NO generation and Th1 response, essential against this deadly disease.

NO Generation from Nitrite at Zinc(II): Role of Thiol Persulfidation in the Presence of Sulfane Sulfur.

Nitrite-to-NO transformation is of prime importance due to its relevance in mammalian physiology. Although such a one-electron reductive transformation at various redox-active metal sites (e.g., Cu and Fe) has been illustrated previously, the reaction at the [ZnII] site in the presence of a sacrificial reductant like thiol has been reported to be sluggish and poorly understood. Reactivity of [(Bn3Tren)ZnII-ONO](ClO4) (1), a nitrite-bound model of the tripodal active site of carbonic anhydrase (CA), toward various organic probes, such as 4-tert-butylbenzylthiol (tBuBnSH), 2,4-di-tert-butylphenol (2,4-DTBP), and 1-fluoro-2,4-dinitrobenzene (F-DNB), reveals that the ONO-moiety in the [ZnII]-nitrite coordination motif of complex 1 acts as a mild electrophile. tBuBnSH reacts mildly with nitrite at a [ZnII] site to provide S-nitrosothiol tBuBnSNO prior to the release of NO in 10% yield, whereas the phenolic substrate 2,4-DTBP does not yield the analogous O-nitrite compound (ArONO). The presence of sulfane sulfur (S0) species such as elemental sulfur (S8) and organic polysulfides (tBuBnSnBntBu) during the reaction of tBuBnSH and [ZnII]-nitrite (1) assists the nitrite-to-NO conversion to provide NO yields of 65% (for S8) and 76% (for tBuBnSnBntBu). High-resolution mass spectrometry (HRMS) analyses on the reaction of [ZnII]-nitrite (1), tBuBnSH, and S8 depict the formation of zinc(II)-persulfide species [(Bn3Tren)ZnII-Sn-BntBu]+ (where n = 2, 3, 4, 5, and 6). Trapping of the persulfide species (tBuBnSS-) with 1-fluoro-2,4-dinitrobenzene (F-DNB) confirms its intermediacy. The significantly higher nucleophilicity of persulfide species (relative to thiol/thiolate) is proposed to facilitate the reaction with the mildly electrophilic [ZnII]-nitrite (1) complex. Complementary analyses, including multinuclear NMR, electrospray ionization-MS, UV-vis, and trapping of reactive S-species, provide mechanistic insights into the sulfane sulfur-assisted reactions between thiol and nitrite at the tripodal [ZnII]-site. These findings suggest the critical influential roles of various reactive sulfur species, such as sulfane sulfur and persulfides, in the nitrite-to-NO conversion.

Synthesis, characterization and anti-inflammatory activity of selenium nanoparticles stabilized by aminated yeast glucan

Improving the dispersed stability of selenium nanoparticles (SeNPs) is the key to its application. In this study, yeast glucan with different degrees of amination (BNs) were used as stabilizers and capping agent to prepare dispersed SeNPs. The size, storage stability, and morphology of BNs/SeNPs were characterized. Results show that BNs/SeNPs presented positive potential and spherical morphologies with average particle size about 100–300 nm and kept stable at room temperature for a long time. The CCK-8 assay showed that BNs/SeNPs had significantly lower toxicity to RAW264.7 cells than SeNPs. Moreover, BNs/SeNPs could inhibit the generation of NO, IL-1β and IL-6 effectively in RAW 264.7 macrophages induced by LPS, and down-regulate the mRNA transcription of iNOS, IL-1β, IL-6 and chemokines (CCL2 and CCL5), indicating that BNs/SeNPs had good anti-inflammatory activity. Therefore, aminated yeast glucan could improve the stability and bioactivity of SeNPs simultaneously, which is a promising stabilizer for SeNPs.

Modeling Selenoprotein Se-Nitrosation: Synthesis of a Se-Nitrososelenocysteine with Persistent Stability.

The Se-nitrosation in selenoproteins such as glutathione peroxidase and thioredoxin reductase to produce Se-nitrososelenocysteines (Sec-SeNOs) has been proposed to play crucial roles in signaling processes mediated by reactive nitrogen species and nitrosative-stress responses, although chemical evidence for the formation of Sec-SeNOs has been elusive not only in proteins but also in small-molecule systems. Herein, we report the first synthesis of a Sec-SeNO by employing a selenocysteine model system that bears a protective molecular cradle. The Sec-SeNO was characterized using 1H and 77Se nuclear magnetic resonance as well as ultraviolet/visible spectroscopy and found to have persistent stability at room temperature in solution. The reaction processes involving the Sec-SeNO provide experimental information that serves as a chemical basis for elucidating the reaction mechanisms involving the SeNO species in biological functions, as well as in selenol-catalyzed NO generation from S-nitrosothiols.

Anti-inflammatory activity of phenolics from Hypericum japonicum

Two new phenolics, one xanthonoid (1) and one phloroglucinol derivative (2), together with eighteen known phenolics (3–20), were isolated from the aerial parts of Hypericum japonicum. Their structures were established by extensive spectral analysis, and the absolute configuration of compound 1 was determined by comparison of the calculated and experimental circular dichroism spectra. An anti-inflammatory activity assay revealed that compound 1 exhibited effective inhibitory effects on NO generation in LPS-stimulated RAW 264.7 macrophages, with an IC50 value of 6.34 μg/mL.

Cinnamaldehyde inhibits Enterococcus faecalis biofilm formation and promotes clearance of its colonization by modulation of phagocytes in vitro

The nosocomial pathogen, Enterococcus faecalis plays a crucial role in the pathogenesis of variety of infections including endocarditis, urinary tract, and recurrent root canal infections. Primary virulence factors of E. faecalis such as biofilm formation, gelatinase production and suppression of host innate immune response can severely harm host tissue. Thus, novel treatments are needed to prevent E. faecalis biofilm development and pathogenicity due to the worrisome rise in enterococcal resistance to antibiotics. The primary phytochemical in cinnamon essential oils, cinnamaldehyde, has shown promising efficacy against a variety of infections. Here, we looked into how cinnamaldehyde affected the growth of biofilms, the activity of the enzyme gelatinase, and gene expression in E. faecalis. In addition, we looked at the influence of cinnamaldehyde on RAW264.7 macrophages' interaction with biofilm and planktonic E. faecalis in terms of intracellular bacterial clearance, NO generation, and macrophage migration in vitro. According to our research, cinnamaldehyde attenuated the biofilm formation potential of planktonic E. faecalis and gelatinase activity of the biofilm at non-lethal concentrations. The expression of the quorum sensing fsr locus and its downstream gene gelE in biofilms were also found to be significantly downregulated by cinnamaldehyde. Results also demonstrated that cinnamaldehyde treatment increased NO production, intracellular bacterial clearance, and migration of RAW264.7 macrophages in presence of both biofilm and planktonic E. faecalis. Overall these results suggest that cinnamaldehyde has the ability to inhibit E. faecalis biofilm formation and modulate host innate immune response for better clearance of bacterial colonization.

Notch3/Hes5 Induces Vascular Dysfunction in Hypoxia-Induced Pulmonary Hypertension Through ER Stress and Redox-Sensitive Pathways.

Notch3 (neurogenic locus notch homolog protein 3) is implicated in vascular diseases, including pulmonary hypertension (PH)/pulmonary arterial hypertension. However, molecular mechanisms remain elusive. We hypothesized increased Notch3 activation induces oxidative and endoplasmic reticulum (ER) stress and downstream redox signaling, associated with procontractile pulmonary artery state, pulmonary vascular dysfunction, and PH development. Studies were performed in TgNotch3R169C mice (harboring gain-of-function [GOF] Notch3 mutation) exposed to chronic hypoxia to induce PH, and examined by hemodynamics. Molecular and cellular studies were performed in pulmonary artery smooth muscle cells from pulmonary arterial hypertension patients and in mouse lung. Notch3-regulated genes/proteins, ER stress, ROCK (Rho-associated kinase) expression/activity, Ca2+ transients and generation of reactive oxygen species, and nitric oxide were measured. Pulmonary vascular reactivity was assessed in the presence of fasudil (ROCK inhibitor) and 4-phenylbutyric acid (ER stress inhibitor). Hypoxia induced a more severe PH phenotype in TgNotch3R169C mice versus controls. TgNotch3R169C mice exhibited enhanced Notch3 activation and expression of Notch3 targets Hes Family BHLH Transcription Factor 5 (Hes5), with increased vascular contraction and impaired vasorelaxation that improved with fasudil/4-phenylbutyric acid. Notch3 mutation was associated with increased pulmonary vessel Ca2+ transients, ROCK activation, ER stress, and increased reactive oxygen species generation, with reduced NO generation and blunted sGC (soluble guanylyl cyclase)/cGMP signaling. These effects were ameliorated by N-acetylcysteine. pulmonary artery smooth muscle cells from patients with pulmonary arterial hypertension recapitulated Notch3/Hes5 signaling, ER stress and redox changes observed in PH mice. Notch3 GOF amplifies vascular dysfunction in hypoxic PH. This involves oxidative and ER stress, and ROCK. We highlight a novel role for Notch3/Hes5-redox signaling and important interplay between ER and oxidative stress in PH.

Thiol and H2S-Mediated NO Generation from Nitrate at Copper(II).

Reduction of nitrate is an essential, yet challenging chemical task required to manage this relatively inert oxoanion in the environment and biology. We show that thiols, ubiquitous reductants in biology, convert nitrate to nitric oxide at a Cu(II) center under mild conditions. The β-diketiminato complex [Cl2NNF6]Cu(κ2-O2NO) engages in O-atom transfer with various thiols (RSH) to form the corresponding copper(II) nitrite [CuII](κ2-O2N) and sulfenic acid (RSOH). The copper(II) nitrite further reacts with RSH to give S-nitrosothiols RSNO and [CuII]2(μ-OH)2 en route to NO formation via [CuII]-SR intermediates. The gasotransmitter H2S also reduces nitrate at copper(II) to generate NO, providing a lens into NO3-/H2S crosstalk. The interaction of thiols with nitrate at copper(II) releases a cascade of N- and S-based signaling molecules in biology.

Diagnostic value and underlying mechanism of nasal nitric oxide in eosinophilic chronic rhinosinusitis with nasal polyps

PurposeNitric oxide (NO) is an important messenger molecule widely present in the human body. However, the role of nasal NO (nNO) in eosinophilic chronic rhinosinusitis with nasal polyps (Eos CRSwNP) remain unclear. This study aimed to investigate the diagnostic value and underlying mechanism of nNO in Eos CRSwNP. MethodsThe medical records of 84 non-Eos CRSwNP patients, 55 Eos CRSwNP patients, and 37 control subjects were retrospectively reviewed. The diagnostic value of nNO for Eos CRSwNP was assessed. The expression of inducible nitric oxide synthase (iNOS), endothelial nitric oxide synthase (eNOS), and tight junctions (TJs) components claudin-1, occludin, and ZO-1 was detected in the nasal polyps. Primary human nasal epithelial cells (HNECs) were co-treated with eNOS inhibitor (L-NAME) or Akt inhibitor (MK-2206), interleukin (IL)−13, and dexamethasone (Dex). The level of NO and the expression of TJs and Akt/eNOS pathways were examined. ResultsThe nNO levels of the CRSwNP group were significantly lower than those of the control group. Compared with the non-Eos CRSwNP group, the Eos CRSwNP group showed higher nNO level. The combination of nNO level, eosinophilic percentage, and posterior ethmoid score had a better predictive value for Eos CRSwNP (AUC = 0.855). The expression of iNOS, eNOS, and p-eNOS was higher in the CRSwNP groups than in the control group, and p-eNOS expression was higher in the Eos CRSwNP group than in the non-Eos CRSwNP group. The expression of TJs was lower in the Eos CRSwNP group than in the non-Eos CRSwNP and control group. IL-13 decreased TJ expression in HNECs, while Dex promoted Akt and eNOS phosphorylation, NO production and TJ expression. Furthermore, these effects of Dex were inhibited by L-NAME and MK-2206 in HNECs. ConclusionnNO may have a high diagnostic value in Eos CRSwNP, and Akt/eNOS pathway may promote the generation of NO to protect TJs. NO may have a potentially important role in the diagnosis and treatment of Eos CRSwNP.

Biomimetic catheter surface with dual action NO-releasing and generating properties for enhanced antimicrobial efficacy.

Infection of indwelling catheters is a common healthcare problem, resulting in higher morbidity and mortality. The vulnerable population reliant on catheters post-surgery for food and fluid intake, blood transfusion, or urinary incontinence or retention is susceptible to hospital-acquired infection originating from the very catheter. Bacterial adhesion on catheters can take place during the insertion or over time when catheters are used for an extended period. Nitric oxide-releasing materials have shown promise in exhibiting antibacterial properties without the risk of antibacterial resistance which can be an issue with conventional antibiotics. In this study, 1, 5, and 10 wt % selenium (Se) and 10 wt % S-nitrosoglutathione (GSNO)-incorporated catheters were prepared through a layer-by-layer dip-coating method to demonstrate NO-releasing and NO-generating capability of the catheters. The presence of Se on the catheter interface resulted in a 5 times higher NO flux in 10% Se-GSNO catheter through catalytic NO generation. A physiological level of NO release was observed from 10% Se-GSNO catheters for 5 d, along with an enhanced NO generation via the catalytic activity as Se was able to increase NO availability. The catheters were also found to be compatible and stable when subjected to sterilization and storage, even at room temperature. Additionally, the catheters showed a 97.02% and 93.24% reduction in the adhesion of clinically relevant strains of Escherichia coli and Staphylococcus aureus, respectively. Cytocompatibility testing of the catheter with 3T3 mouse fibroblast cells supports the material's biocompatibility. These findings from the study establish the proposed catheter as a prospective antibacterial material that can be translated into a clinical setting to combat catheter-related infections.

Potential mechanism of transient receptor potential cation channel subfamilyV member1 combined with an ATP‑sensitive potassium channel in severe preeclampsia.

Severe preeclampsia is one of the most serious obstetric diseases. However, the pathogenesis of the disease is not fully understood. In the present study, placental artery and blood serum was collected from patients with severe preeclampsia, as well as from normal pregnant women. The results of reverse transcription-quantitative (q)PCR, western blotting, and immunohistochemical staining revealed markedly decreased transient receptor potential cation channel subfamily V member 1 (TRPV1), ATP-sensitive potassium channel (KATP) subtype Kir6.1/SUR2B and endothelial nitric oxide synthase (eNOS) expression in severe preeclampsia tissue specimens compared with those in samples from normal pregnant women. The nitrate reduction method indicated lower NO levels in the tissue specimens and serum of patients with severe preeclampsia. Moreover, hematoxylin-eosin staining showed that the endothelial cell layer in the placental artery of patients with severe preeclampsia was notably damaged. To investigate the potential role of TRPV1-KATP channels in severe preeclampsia, HUVECs were used for in vitro experiments. The samples were divided into a control group, a TRPV1 agonist group (capsaicin) and a TRPV1 inhibitor group (capsazepine). qPCR and western blotting revealed that the relative gene and protein expression levels of TRPV1, Kir6.1, SUR2B and eNOS in the control group were significantly lower than those in the capsaicin group and considerably higher than those in the capsazepine group. Based on previous studies and the results of the present study, we hypothesized that impairment of the endothelial TRPV1-KATP channels results in decreased eNOS/NO pathway activity, which may be one of the mechanisms involved in severe preeclampsia. The increase in NO generation mediated by TRPV1-KATP may be a suitable target for the management of severe preeclampsia.

NO-chemistry during methanol combustion from rich to lean conditions—exploring the fuel property influence mechanisms on different NO pathways

Methanol is a favorable hydrogen-based energy storage media, and fire methanol in industrial boiler and furnace can achieve renewable and carbon-free energy supplies in industrial heating field. Knowledges about NO formation during methanol combustion are very limited, and in particular that under furnace combustion condition with excess oxygen and high temperature (up to 1500 °C) was lacked. This paper examined NO generation of methanol under broader operation range. By comparing its behavior with the well-studied methane, the NO-chemistry dependence on methanol fuel property was analyzed. Results showed the fuel property of methanol has opposite influence on NO generation between rich and lean combustion. During lean combustion, the O atom concentration was greatly increased to promote the conversion of N2 to NO via N2+O↔N+NO under high temperature. This fuel-related mechanism makes NO generation being independent on residence time but closely correlated to fuel concentration. This proposed O enhanced mechanism also explains some previous observations that the contribution from NNH and N2O pathway is larger for methanol than methane at lean condition. Under fuel rich combustion, however, methanol generates NO mainly via prompt pathway, sharing the similar mechanism to methane but with much reduced level due to the decreased CHi concentration.

Renal Denervation Helps Preserve the Ejection Fraction by Preserving Endocardial-Endothelial Function during Heart Failure.

Renal denervation (RDN) protects against hypertension, hypertrophy, and heart failure (HF); however, it is not clear whether RDN preserves ejection fraction (EF) during heart failure (HFpEF). To test this hypothesis, we simulated a chronic congestive cardiopulmonary heart failure (CHF) phenotype by creating an aorta-vena cava fistula (AVF) in the C57BL/6J wild type (WT) mice. Briefly, there are four ways to create an experimental CHF: (1) myocardial infarction (MI), which is basically ligating the coronary artery by instrumenting and injuring the heart; (2) trans-aortic constriction (TAC) method, which mimics the systematic hypertension, but again constricts the aorta on top of the heart and, in fact, exposes the heart; (3) acquired CHF condition, promoted by dietary factors, diabetes, salt, diet, etc., but is multifactorial in nature; and finally, (4) the AVF, which remains the only one wherein AVF is created ~1 cm below the kidneys in which the aorta and vena cava share the common middle-wall. By creating the AVF fistula, the red blood contents enter the vena cava without an injury to the cardiac tissue. This model mimics or simulates the CHF phenotype, for example, during aging wherein with advancing age, the preload volume keeps increasing beyond the level that the aging heart can pump out due to the weakened cardiac myocytes. Furthermore, this procedure also involves the right ventricle to lung to left ventricle flow, thus creating an ideal condition for congestion. The heart in AVF transitions from preserved to reduced EF (i.e., HFpEF to HFrEF). In fact, there are more models of volume overload, such as the pacing-induced and mitral valve regurgitation, but these are also injurious models in nature. Our laboratory is one of the first laboratories to create and study the AVF phenotype in the animals. The RDN was created by treating the cleaned bilateral renal artery. After 6 weeks, blood, heart, and renal samples were analyzed for exosome, cardiac regeneration markers, and the renal cortex proteinases. Cardiac function was analyzed by echocardiogram (ECHO) procedure. The fibrosis was analyzed with a trichrome staining method. The results suggested that there was a robust increase in the exosomes' level in AVF blood, suggesting a compensatory systemic response during AVF-CHF. During AVF, there was no change in the cardiac eNOS, Wnt1, or β-catenin; however, during RDN, there were robust increases in the levels of eNOS, Wnt1, and β-catenin compared to the sham group. As expected in HFpEF, there was perivascular fibrosis, hypertrophy, and pEF. Interestingly, increased levels of eNOS suggested that despite fibrosis, the NO generation was higher and that it most likely contributed to pEF during HF. The RDN intervention revealed an increase in renal cortical caspase 8 and a decrease in caspase 9. Since caspase 8 is protective and caspase 9 is apoptotic, we suggest that RDN protects against the renal stress and apoptosis. It should be noted that others have demonstrated a role of vascular endothelium in preserving the ejection by cell therapy intervention. In the light of foregoing evidence, our findings also suggest that RDN is cardioprotective during HFpEF via preservation of the eNOS and accompanied endocardial-endothelial function.

Glutathione/Glucose-Depleting Nanoparticles with NO Generation for Ferroptosis/Starvation/NO-Induced Cancer Therapy

Depleting intracellular glutathione (GSH) has emerged as a potent strategy to combat cancer. However, the existing GSH-depleting agents are too toxic or ineffective and standalone GSH depletion fails to yield a satisfactory curative effect. Herein, we present an intelligent nanoparticle that possesses GSH depletion, glucose consumption accompanied with H2O2 production, and NO generation properties for multimodal cancer therapy. The nanoparticle is constructed by synthesis of tetrasulfide bond-doped mesoporous silica nanoparticles followed by conjugating glucose oxidase (GOx) on the surface and loading l-arginine (l-Arg) into the mesopores. In this nanoparticle, the doped tetrasulfide bonds can quickly deplete GSH, which increases the cellular reactive oxygen species concentration to induce ferroptosis and meanwhile triggers particle biodegradation to expose the loaded l-Arg. Moreover, the elevated H2O2 level activates l-Arg to release NO for NO therapy. GOx consumes glucose to initiate starvation therapy and simultaneously produces a large amount of H2O2. Importantly, the produced H2O2 can not only potentiate ferroptosis but also promote NO release to enhance NO therapy. Besides, NO could in turn improve the efficacy of starvation therapy by damaging the mitochondria to block energy supply. In vitro and in vivo studies demonstrate that the nanoparticles show a great synergistic effect of ferroptosis/starvation/NO therapy, which can significantly kill cancer cells and remarkably inhibit tumor growth without obvious side effects. Therefore, we think that the designed nanoparticles may provide a promising paradigm for synergistic cancer therapy and hold a prospect in clinical trials.

Numerical Simulation of NO x Formation in Non-Premixed Methane Combustion Using Internal Flue Gas Recirculation

ABSTRACT Internal flue gas recirculation (IFGR) is one of the most effective techniques for NO x reduction in boilers. Previous studies mainly focused on premixed combustion; however, the NO x formation principles in non-premixed methane/air flames are still unclear. This work aims to investigate the NO x formation mechanisms in non-premixed methane combustion at various IFGR rates. A series of three-dimensional computational fluid dynamics (CFD) simulations with detailed mechanisms was conducted. The results show that NO x is generated below 30 mg/m3 for IFGR rates higher than 17.7%, corresponding to the oxygen concentration in the oxidant mixture below 0.15. In high IFGR rates, the incompletely mixed oxidants and the presence of the central recirculation zones weakens the NO x reduction performance. Influenced by the decreased temperature by IFGR, the generation of thermal NO x is largely eliminated from 66 to 1 mg/m3. Prompt NO x contributes more than thermal NO x for the IFGR rates above 12.2%. The reaction range of thermal NO x is found moving upstream toward the nozzle with the axial distance of 0.1 m at most. IFGR gradually reduces prompt NO x but its spatial reaction ranges are hardly influenced. IFGR has no obvious effects both on the reaction rates and ranges on the minorities of the N2O and the NNH routes. This work connects the IFGR rates and the NO x formation pathways in non-premixed methane combustion, and highlights the importance of eliminating prompt NO x to achieve low-NO x combustion rather than sole NO x suppression method, which can provide foundation for designing low-NO x techniques.

Simulation study on fuel-nitrogen migration characteristics of oxy-fuel co-combustion of various ultra-low volatile coal-based solid fuels

The co-combustion of various ultra-low volatile coal-based solid fuels (UVCFs) under oxy-fuel condition could consume semi-coke and residual carbon cleanly and efficiently. However, the fuel-nitrogen (fuel-N) migration behaviors of various UVCFs blends in O2/CO2 atmosphere are still unclear. In addition, the heterogeneous reactions on surfaces of char could also affect the synergistic effects between various UVCFs blend. Here, the fuel-N migration features of various UVCFs in O2/CO2 atmosphere were investigated by Chemkin simulation and the oxy-fuel co-combustion mechanism of various coal-based solid fuels (OCF mechanism) included heterogeneous reactions was developed. Moreover, the methods of sensitivity and rate of production analyses were both employed to clarify the synergistic effects on nitrogen conversion pathways of various blends. The heterogeneous reaction between char and NO (R15) is the key reaction for NO reduction in primary zone. The free radicals OH and H provided by UVCFs could react with main NO precursors NCO, HNCO, HOCN, NH and NH2 to generate NO. The conversion pathways of HCN to NO are more complex than those of NH3 to NO. The rises of residual carbons proportions and temperature in primary zone (T1) could both reduce the NO formation amount due to the promoted R15. The sensitivity coefficients (S) on NO formation of 50% SS/50% CR blend in the burnout zone are lower than those of 50% SS/50% FR blend. The transformations of HNCO, HNO and NO2 to NO and the heterogeneous reactions of NO could both be enhanced with the O2 concentration in burnout zone. The increasing burnout air position (Pb) results in the rise of NO generation owing to that the NO reducing reactions R15 and R16 are greatly inhibited with the Pb raised. The present study could be beneficial for the clean and effective utilization of UVCFs, together with the reduce of NOx emission and realization of carbon neutral in China.

FGL2 deficiency alleviates maternal inflammation-induced blood-brain barrier damage by blocking PI3K/NF-κB mediated endothelial oxidative stress.

The impairment of blood-brain barrier (BBB) is one of the key contributors to maternal inflammation induced brain damage in offspring. Our previous studies showed Fibrinogen-like protein 2 (FGL2) deficiency alleviated maternal inflammation induced perinatal brain damage. However, its role in BBB remains undefined. Lipopolysaccharide (LPS) was intraperitoneally injected to dams at Embryonic day 17 to establish maternal inflammation model. FGL2 knockout mice and primary brain microvascular endothelial cells (BMECs) were used for the in-vivo and in-vitro experiments. BBB integrity was assessed by sodium fluorescein extravasation and tight junction (TJ) protein expression. Oxidative stress and the activation of PI3K/NF-κB pathway were evaluated to explore the mechanisms underlying. Upon maternal inflammation, BBB integrity was remarkedly reduced in neonatal mice. Meanwhile, FGL2 expression was consistently increased in BBB-impaired brain as well as in LPS-treated BMECs. Moreover, FGL2 deficiency attenuated the hyperpermeability of BBB, prevented the decline of TJ proteins, and reduced the cytokine expressions in LPS-exposed pups. Mechanistically, the indicators of oxidative stress, as well as the activation of PI3K/NF-κB pathway, were upregulated after LPS exposure in vivo and in vitro. FGL2 deletion decreased the generation of ROS and NO, reduced the endothelial iNOS and NOX2 expressions, and suppressed the PI3K/NF-κB pathway activation. Besides, inhibition of PI3K by LY294002 decreased the oxidative stress in LPS-treated wild-type BMECs. While, overexpression of PI3K by lentivirus reemerged the induction of NOX2 and iNOS as well as NF-κB activation in FGL2-deleted BMECs. Our findings indicate that FGL2 deficiency alleviates the maternal inflammation-induced BBB disruption by inhibiting PI3K/NF-κB mediated oxidative stress in BMECs. Targeting FGL2 may provide a new therapy for prenatal brain damage of offspring.

Regulatory mechanisms of kaempferol on iNOS expression in RINm5F β-cells under exposure to interleukin-1β

Proinflammatory cytokines and NO play crucial roles in islet β-cells dysfunction. Though anti-inflammatory effects of kaempferol were revealed in several studies, the detailed mechanisms remain unclear. This study explored protective actions of kaempferol in interleukin-1β-treated RINm5F β-cells. Kaempferol significantly inhibited NO generation, iNOS protein, and iNOS mRNA level. Promoter study, EMSA, and κB-dependent reporter assay showed that kaempferol inhibited NF-κB-mediated iNOS gene transcription. Also, we found that kaempferol accelerated iNOS mRNA instability in iNOS 3′-UTR construct and actinomycin D chase studies. Additionally, kaempferol reduced iNOS protein stability in cycloheximide chase study and it inhibited NOS enzyme activity. Kaempferol inhibited ROS generation and preserved cell viability, and it improved insulin release. These findings suggest that kaempferol appears to be helpful in protecting islet β-cells, thereby supports kaempferol as a supplementary therapeutic candidate in inhibiting the incidence and progression of diabetes mellitus.