Endogenous Nitric Oxide Production Research Articles

Glucopeptide Superstructure Hydrogel Promotes Surgical Wound Healing Following Neoadjuvant Radiotherapy by Producing NO and Anticellular Senescence.

Neoadjuvant radiotherapy, a preoperative intervention regimen for reducing the stage of primary tumors and surgical margins, has gained increasing attention in the past decade. However, radiation-induced skin damage during neoadjuvant radiotherapy exacerbates surgical injury, remarkably increasing the risk of refractory wounds and compromising the therapeutic effects. Radiation impedes wound healing by increasing the production of reactive oxygen species and inducing cell apoptosis and senescence. Here, a self-assembling peptide (R-peptide) and hyaluronic-acid (HA)-based and cordycepin-loaded superstructure hydrogel is prepared for surgical incision healing after neoadjuvant radiotherapy. Results show that i) R-peptide coassembles with HA to form biomimetic fiber bundle microstructure, in which R-peptide drives the assembly of single fiber through π-π stacking and other forces and HA, as a single fiber adhesive, facilitates bunching through electrostatic interactions. ii) The biomimetic superstructure contributes to the adhesion and proliferation of cells in the surgical wound. iii) Aldehyde-modified HA provides dynamic covalent binding sites for cordycepin to achieve responsive release, inhibiting radiation-induced cellular senescence. iv) Arginine in the peptides provides antioxidant capacity and a substrate for the endogenous production of nitric oxide to promote wound healing and angiogenesis of surgical wounds after neoadjuvant radiotherapy.

Oral nitrate-reducing bacteria as potential probiotics for blood pressure homeostasis.

Hypertension is a leading cause of morbidity and mortality worldwide and poses a major risk factor for cardiovascular diseases and chronic kidney disease. Research has shown that nitric oxide (NO) is a vasodilator that regulates vascular tension and the decrease of NO bioactivity is considered one of the potential pathogenesis of essential hypertension. The L-arginine-nitric oxide synthase (NOS) pathway is the main source of endogenous NO production. However, with aging or the onset of diseases, the function of the NOS system becomes impaired, leading to insufficient NO production. The nitrate-nitrite-NO pathway allows for the generation of biologically active NO independent of the NOS system, by utilizing endogenous or dietary inorganic nitrate and nitrite through a series of reduction cycles. The oral cavity serves as an important interface between the body and the environment, and dysbiosis or disruption of the oral microbiota has negative effects on blood pressure regulation. In this review, we explore the role of oral microbiota in maintaining blood pressure homeostasis, particularly the connection between nitrate-reducing bacteria and the bioavailability of NO in the bloodstream and blood pressure changes. This review aims to elucidate the potential mechanisms by which oral nitrate-reducing bacteria contribute to blood pressure homeostasis and to highlight the use of oral nitrate-reducing bacteria as probiotics for oral microbiota intervention to prevent hypertension.

Systemic nitric oxide metabolites and the chance of pre-diabetes regression to normoglycemia: A 9-year cohort study

Introduction: We aimed to track longitudinal changes of glycemic status in subjects with pre-diabetes (Pre-DM) in relation to their baseline levels of systemic nitric oxide (NO) production [i.e., measured as serum NO metabolites (NOx), crude and body weight (BW)-adjusted NOx to creatinine ratio (NOx-to-Cr)] over 9 years. Methods: This cohort study included 541 middle-aged Iranian men and women with Pre-DM, recruited in 2006-2008 and followed up to 2015-2017. The colorimetric Griess method was used to measure serum NOx concentration. Multinomial logistic regression analyses estimated the odds ratios (OR) of Pre-DM regression and progression across tertiles (tertile 3 vs. tertile 1 and tertile 2) of serum NOx, crude, and BW-adjusted NOx-to-Cr ratio. Results: Participants who regressed to normoglycemia (NG) had a higher BW-adjusted NOx-to-Cr ratio than those who developed type 2 diabetes (T2D) or those who remained Pre-DM (0.52±0.34 vs. 0.43±0.25 and 0.48±0.29, P=0.023). Higher BW-adjusted NOx-to-Cr increased chance of returning to NG (OR=2.05, 95% CI= 0.98-4.32, P=0.058) and decreased levels of 2h-serum glucose over time (Ptime×group=0.025), as well as the decreased overall mean of fasting (106, 95% CI=103-109 vs. 110, 95% CI=108-112 mg/dL, P=0.008) and 2h-serum glucose (153, 95% CI=146-159 vs. 163, 95% CI=158-168 mg/dL, P=0.018). Conclusion: A higher endogenous NO production (i.e., indirectly measured by BW- and Cr-adjusted serum NOx concentration) in Pre-DM subjects is associated with the chance of returning to NG.

Nitric Oxide Promoted the Seed Germination of Cynanchum auriculatum under Cadmium Stress

Cynanchum auriculatum, an early food-medicine homologous plant native to Asia, possesses significant nutritional and health benefits. However, the presence of cadmium (Cd) in the soil poses a hazard to the germination and growth of C. auriculatum. As nitric oxide (NO) plays a vital role in plant resistance to heavy metal stress, we used three different concentrations of SNP treatment during the germination phase, aiming to alleviate the inhibitory effects of Cd stress on the seed germination of C. auriculatum. The results indicated that when compared to seeds treated with SNP concentrations of 0.2 mM and 0.8 mM, C. auriculatum seeds treated with 0.4 mM SNP exhibited an improved germination rate and germination index, as well as longer hypocotyl. Furthermore, in comparison to NOS-like, the SNP application stimulated the production of endogenous NO through NR catalysis. Additional investigations showed that the ABA level decreased while the GA level increased under normal conditions, while the SNP application enhanced the accumulation of both ABA and GA in C. auriculatum seeds under Cd stress. Histochemical staining and biochemical indicators demonstrated that SNP treatment enhanced the enzymatic activity of SOD, POD, and CAT, while inhibiting the production of hydrogen peroxide and superoxide anion. Moreover, SNP treatment resulted in increased α-amylase activity, which facilitated starch hydrolysis and the generation of soluble sugar. Ultimately, the seed vitality of C. auriculatum under Cd stress was promoted. Our findings present a theoretical framework for the application of SNP in the seed germination mechanism of C. auriculatum and establish the groundwork for comprehending the physiological role of NO under Cd stress.

Nitric Oxide (NO) regulation of Dendritic cells (DC) metabolism and immune effector functions

Abstract Dendritic cell (DC) activation is characterized by a sustained commitment to glycolysis, a requirement for survival in DC subsets expressing inducible nitric oxide synthase (iNOS, encoded by Nos2 gene). Nitric oxide (NO) can mediate both host-protective and host-cytotoxic effects by interfering with pathogen replication and/or by inhibiting the host mitochondrial respiration, resulting in metabolic rewiring in DCs. These phenomena primarily have been studied in DCs from the classic laboratory inbred mouse strain C57BL/6J (B6), where DCs experience a loss of mitochondrial function due to NO accumulation. To assess the conservation of NO-driven metabolic regulation in DCs, we compared B6 mice to the wild-derived genetically divergent PWD/PhJ (PWD) strain. We show preserved mitochondrial respiration and enhanced post-activation survival in LPS-stimulated PWD DCs due to attenuated NO production. To genetically map PWD’s NO phenotype, we used a congenic mouse strain (B6.PWD-Chr11.2; 11.2) that carries a PWD-derived portion of chromosome 11, including Nos2, on a B6 background. The 11.2 DCs show comparable iNOS expression with lower NO production levels than B6 DCs. We demonstrate that activated 11.2 DCs maintain mitochondrial respiration and TCA cycle carbon flux, compared with B6 DCs. However, reduced NO production by the PWD Nos2 allele results in impaired cellular control of Listeria monocytogenes replication. These studies establish a natural genetic model for restrained endogenous NO production and suggest a useful model to investigate the contribution/regulation of NO in DC metabolism and immune function. This work was supported by the National Institutes of Health (NIH), National Institute of Allergy and Infectious Diseases (P30GM118228, 1R21AI135385-01A, T32AI055402-15, and R21 AI145306), the NIH, National Institute of Neurological Disorders and Stroke (R01 NS097596), and the National Multiple Sclerosis Society (RG-1901-33309).

Recent advances in diverse nanosystems for nitric oxide delivery in cancer therapy.

Gas therapy has been proven to be a promising and advantageous treatment option for cancers. Studies have shown that nitric oxide (NO) is one of the smallest structurally significant gas molecules with great potential to suppress cancer. However, there is controversy and concern about its use as it exhibits the opposite physiological effects based on its levels in the tumor. Therefore, the anti-cancer mechanism of NO is the key to cancer treatment, and rationally designed NO delivery systems are crucial to the success of NO biomedical applications. This review summarizes the endogenous production of NO, its physiological mechanisms of action, the application of NO in cancer treatment, and nano-delivery systems for delivering NO donors. Moreover, it briefly reviews challenges in delivering NO from different nanoparticles and the issues associated with its combination treatment strategies. The advantages and challenges of various NO delivery platforms are recapitulated for possible transformation into clinical applications.

Long-term dietary nitrate supplementation slows the progression of established atherosclerosis in ApoE−/− mice fed a high fat diet

Background and aimsAtherosclerosis is associated with a reduction in the bioavailability and/or bioactivity of endogenous nitric oxide (NO). Dietary nitrate has been proposed as an alternate source when endogenous NO production is reduced. Our previous study demonstrated a protective effect of dietary nitrate on the development of atherosclerosis in the apoE−/− mouse model. However most patients do not present clinically until well after the disease is established. The aims of this study were to determine whether chronic dietary nitrate supplementation can prevent or reverse the progression of atherosclerosis after disease is already established, as well as to explore the underlying mechanism of these cardiovascular protective effects.Methods60 apoE−/− mice were given a high fat diet (HFD) for 12 weeks to allow for the development of atherosclerosis. The mice were then randomized to (i) control group (HFD + 1 mmol/kg/day NaCl), (ii) moderate-dose group (HFD +1 mmol/kg/day NaNO3), or (iii) high-dose group (HFD + 10 mmol/kg/day NaNO3) (20/group) for a further 12 weeks. A group of apoE−/− mice (n = 20) consumed a normal laboratory chow diet for 24 weeks and were included as a reference group.ResultsLong-term supplementation with high dose nitrate resulted in ~ 50% reduction in plaque lesion area. Collagen expression and smooth muscle accumulation were increased, and lipid deposition and macrophage accumulation were reduced within atherosclerotic plaques of mice supplemented with high dose nitrate. These changes were associated with an increase in nitrite reductase as well as activation of the endogenous eNOS-NO pathway.ConclusionLong-term high dose nitrate significantly attenuated the progression of established atherosclerosis in the apoE−/− mice fed a HFD. This appears to be mediated in part through a XOR-dependent reduction of nitrate to NO, as well as enhanced eNOS activation via increased Akt and eNOS phosphorylation.

The Effects of Pregnancy on Amino Acid Levels and Nitrogen Disposition.

Limited data are available on the effects of pregnancy on the maternal metabolome. Therefore, the objective of this study was to use metabolomics analysis to determine pathways impacted by pregnancy followed by targeted confirmatory analysis to provide more powerful conclusions about metabolic alterations during pregnancy. Forty-seven pregnant women, 18-50 years of age were included in this study, with each subject serving as their own control. Plasma samples were collected between 25 and 28 weeks gestation and again ≥3 months postpartum for metabolomics analysis utilizing an HILIC/UHPLC/MS/MS assay with confirmatory targeted specific concentration analysis for 10 of the significantly altered amino acids utilizing an LC/MS assay. Principle component analysis (PCA) on metabolomics data clearly separated pregnant and postpartum groups and identified outliers in a preliminary assessment. Of the 980 metabolites recorded, 706 were determined to be significantly different between pregnancy and postpartum. Pathway analysis revealed three significantly impacted pathways, arginine biosynthesis (p = 2 × 10-5 and FDR = 1 × 10-3), valine, leucine, and isoleucine metabolism (p = 2 × 10-5 and FDR = 2 × 10-3), and xanthine metabolism (p = 4 × 10-5 and FDR = 4 × 10-3). Of these we focused analysis on arginine biosynthesis and branched-chain amino acid (BCAA) metabolism due to their clinical importance and interconnected roles in amino acid metabolism. In the confirmational analysis, 7 of 10 metabolites were confirmed as significant and all 10 confirmed the direction of change of concentrations observed in the metabolomics analysis. The data support an alteration in urea nitrogen disposition and amino acid metabolism during pregnancy. These changes could also impact endogenous nitric oxide production and contribute to diseases of pregnancy. This study provides evidence for changes in both the ammonia-urea nitrogen and the BCAA metabolism taking place during pregnancy.

Bradykinin promotes murine melanoma cell migration and invasion through endogenous production of superoxide and nitric oxide

Spatial confinement and temporal regulation of signaling by nitric oxide (NO) and reactive oxygen species (ROS) occurs in cancer cells. Signaling mediated by NO and ROS was investigated in two sub clones of the murine melanoma B16F10-Nex2 cell line, Nex10C and Nex8H treated or not with bradykinin (BK). The sub clone Nex10C, similar to primary site cells, has a low capacity for colonizing the lungs, whereas the sub clone Nex8H, similar to metastatic cells, corresponds to a highly invasive melanoma. BK-treated Nex10C cells exhibited a transient increase in NO and an inhibition in basal O2− levels. Inhibition of endogenous NO production by l-NAME resulted in detectable levels of O2−. l-NAME promoted Rac1 activation and enhanced Rac1–PI3K association. l-NAME in the absence of BK resulted in Nex10C cell migration and invasion, suggesting that NO is a negative regulator of O2− mediated cell migration and cell invasion. BK-treated Nex8H cells sustained endogenous NO production through the activation of NOS3. NO activated Rac1 and promoted Rac1–PI3K association. NO stimulated cell migration and cell invasion through a signaling axis involving Ras, Rac1 and PI3K. In conclusion, a role for O2− and NO as positive regulators of Rac1–PI3K signaling associated with cell migration and cell invasion is proposed respectively for Nex10C and Nex8H murine melanoma cells.

Immediate Effect of Pranava Pranayama on Oxygen Saturation and Heart Rate in Healthy Volunteers: A Single-Blinded, Randomized Controlled Trial

Introduction: Yoga is known to promote health and wellness in all. Pranava Pranayama is a useful sound based yogic breathing technique with reported benefits such as potentiating vagal tone. Subjects and Methods: This single blinded randomized self-controlled cross-over study was done with 58 participants. The immediate effect of Pranava Pranayama on saturation of oxygen in the blood (SpO2) and heart rate (HR) was determined before and after intervention using pulse oximeter. To avoid extraneous influences due to recording on different days, one half of the subjects were randomized to perform quiet sitting on day 1 while other half did Pranava Pranayama which was then reversed on day 2. Results: Intra group comparison showed significant changes (p < 0.001) in both SpO2 and HR following Pranava Pranayama whereas in the quiet sitting group, there was an insignificant fall in the SpO2 readings but HR was found significant (p < 0.001). Intergroup comparison showed significant differences between groups (p-0.032). Discussion: Cardiovascular changes following Pranava Pranayama may be as a result of audible chanting improving baroreflex sensitivity along with increased endogenous nitric oxide production. This promotes vasodilatation resulting in reduction of BP. The decrease in vascular resistance and an increase in capillary perfusion results in increased oxygen saturation with lesser demand on the heart. Conclusion: This study provides evidence that Pranava Pranayama is an effective technique in enhancing SpO2 and our findings may have therapeutic applications especially in the current pandemic situation.

Low Temperature Plasma Jet Affects Acute Skin Wounds in Diabetic Mice Through Reactive Components.

As a common complication of diabetes, diabetic foot ulcers serious affect the life quality even lead to amputation if it's not properly treated. In this paper, we developed a Low Temperature Plasma Jet (LTPJ) system for treating diabetic foot ulcers on streptozotocin-induced diabetic mice. This system generates time-dependent reactive nitrogen and oxygen species (RNOS), which have temperature below 40°C. The wound area of normal mice was significantly reduced after LTPJ treatment. Histological and immunohistochemistry analysis showed faster deposition of collagen and more vessel formation both in plasma-treated normal and diabetic mice on Day 3. However, diabetic wounds showed poor collagen deposition and angiogenesis on Day 8, which might be the reason of slow wound healing. Reactive nitrogen species (RNS) that generated by LTPJ can promote endogenous nitric oxide (NO) production in diabetic wounds, thus promoting inflammation, stromal deposition, angiogenesis, cell proliferation and remodeling, while excess reactive oxygen species (ROS) will exacerbate oxidative stress in wound tissues of diabetic mice. In conclusion, LTPJ improved acute wound healing in normal mice, increased collagen deposition and angiogenesis in initial diabetic wound healing, but had no significant effect on diabetic wound healing rate.

Abstract 13076: A Rare Stopgain Variant in SLC25A2 Associates With Low Nitric Oxide and Poor Clinical Outcome in Hypoplastic Left Heart Syndrome

Introduction: Mitochondrial respiration defects accompanied by low nitric oxide (NO) are associated with heart failure in congenital heart disease (CHD) patients with hypoplastic left heart syndrome (HLHS). Here we investigated the genetic etiology of low NO in patients with CHD. Hypothesis: Mutations in mitochondrial-related genes involved in NO metabolism contributes to the low NO associated risk for heart failure and need for heart transplantation in HLHS. Methods and Results: We performed a case-control association study among 588 white CHD cases including 41 with HLHS, and 24,143 white controls from the genome aggregation database (gnomAD). A rare conserved stopgain variant (rs562886845) in SLC25A2 encoding mitochondrial ornithine transporter was significantly enriched among the HLHS patients with poor clinical outcome (Group II, Table 1), with 15.8% carrying this mutation, yielding odds ratio of 17.07 ( p = 5.23 х 10 -4 ) in comparison to CHD patients without left ventricular outflow tract obstruction or 7.63 ( p =2.68 х 10 –3 ) in comparison to gnomAD control cohort. Significantly, SLC25A2 is the only mitochondrial transporter exporting asymmetric dimethylarginine, a natural NO synthase inhibitor. The three HLHS patients with this SLC25A2 variant showed very low nasal NO (nNO), a proxy for endogenous NO production capacity. All three patients had received heart transplant, with two being heterozygous and one homozygous for this variant. Significantly, the HLHS patient with the homozygous mutation had nNO at background levels (2.8 nl/min at 7 years of age as compared to >200 nl/min expected nNO). Conclusions: Our findings uncovered an essential role for SLC25A2 in determining NO production capacity in patients with HLHS. As all three HLHS patients with this variant and very low nNO survived with heart transplant, this variant should be further investigated as a genetic marker for predicting the need for early heart transplant in HLHS.

The Effect Of Inorganic Nitrate On Muscle Function In Healthy Females Across The Menstrual Cycle

PURPOSE: Inorganic nitrate (NO3-) supplementation increases nitric oxide (NO) bioavailability and may improve exercise performance. In females, estrogen increases endogenous eNOS production of NO, but estrogen fluctuates throughout the menstrual cycle (MC). It is unknown if different phases of the MC or exogenous NO3- supplementation impact maximal voluntary isometric contraction (MVIC), isokinetic torque, or power in apparently healthy young females. The purpose of this study was to examine potential differences in MVIC, isokinetic torque, and power across the early (EF) and late follicular (LF) phase of the MC, and after either beetroot juice (NO3-containing ~13 mmol NO3-) or identical placebo (PL) supplementation. METHODS: Seven recreationally active women (age: 24.7 ± 4 yrs, VO2peak: 34.4 ± 8 mL/kg/min) with normal MC who were not using contraceptives were recruited in this double-blinded crossover study. Subjects were randomized to consume NO3 or PL, twice daily, for at least 2 days prior to testing that was conducted during EF and again during LF (1-5 and 11-14 days after menses onset, respectively). Subjects also consumed the supplement 2 hours prior to the testing, and a 14-day washout period was utilized between treatments. A linear mixed effects model was used to determine differences between MC phase, across supplements, and interaction effects. MVIC (at 90°), peak torque (PT), PT normalized to bodyweight, time to PT, average PT, and average power were acquired via a Biodex isokinetic dynamometer during knee extension when measured at 180°, 270°, and 360°/second. Data are mean ± SD and significance was determined a priori at p ≤ 0.05. RESULTS: Mixed effects models revealed no significant differences in MVIC, power, or any measures of torque either across the MC, or between the PL and NO3 supplementations (all p ≥ 0.05). There were also no significant interaction effects for MVIC (PL EF: 1.12 ± 0.3; PL LF: 1.10 ± 0.3; NO3 EF: 1.18 ± 0.3; NO3 LF: 1.14 ± 0.3 Hz; p = 0.93) or any other outcomes. CONCLUSIONS: This preliminary data suggests that neither the follicular phase of the menstrual cycle, nor NO3- supplementation, impacts MVIC or outcomes such as peak torque or average power during isokinetic knee extension in healthy young females.

Effects of Citrulline Supplementation on Different Aerobic Exercise Performance Outcomes: A Systematic Review and Meta-Analysis

Supplementation with Citrulline (Cit) has been shown to have a positive impact on aerobic exercise performance and related outcomes such as lactate, oxygen uptake (VO2) kinetics, and the rate of perceived exertion (RPE), probably due to its relationship to endogenous nitric oxide production. However, current research has shown this to be controversial. The main objective of this systematic review and meta-analysis was to analyze and assess the effects of Cit supplementation on aerobic exercise performance and related outcomes, as well as to show the most suitable doses and timing of ingestion. A structured literature search was carried out by the PRISMA® (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and PICOS guidelines in the following databases: Pubmed/Medline, Scopus, and Web of Science (WOS). A total of 10 studies were included in the analysis, all of which exclusively compared the effects of Cit supplementation with those of a placebo group on aerobic performance, lactate, VO2, and the RPE. Those articles that used other supplements and measured other outcomes were excluded. The meta-analysis was carried out using Hedges’ g random effects model and pooled standardized mean differences (SMD). The results showed no positive effects of Cit supplementation on aerobic performance (pooled SMD = 0.15; 95% CI (−0.02 to 0.32); I2, 0%; p = 0.08), the RPE (pooled SMD = −0.03; 95% CI (−0.43 to 0.38); I2, 49%; p = 0.9), VO2 kinetics (pooled SMD = 0.01; 95% CI (−0.16 to 0.17); I2, 0%; p = 0.94), and lactate (pooled SMD = 0.25; 95% CI (−0.10 to 0.59); I2, 0%; p = 0.16). In conclusion, Cit supplementation did not prove to have any benefits for aerobic exercise performance and related outcomes. Where chronic protocols seemed to show a positive tendency, more studies in the field are needed to better understand the effects.

Melatonin-Induced Inhibition of Shiraia Hypocrellin A Biosynthesis Is Mediated by Hydrogen Peroxide and Nitric Oxide.

Melatonin (MLT), an evolutionarily conserved pleiotropic molecule, is implicated in numerous physiological processes in plants and animals. However, the effects of MLT on microbes have seldom been reported. In this study, we examined the influence of exogenous MLT on the growth and hypocrellin biosynthesis of bambusicolous fungus Shiraia sp. S9. Hypocrellin A (HA) is a photoactivated and photoinduced perylenequinone (PQ) toxin in Shiraia. Exogenous MLT at 100.00 μM not only decreased fungal conidiation and spore germination but inhibited HA contents significantly in fungal cultures under a light/dark (24 h:24 h) shift. MLT treatment was associated with higher activity of antioxidant enzymes (superoxide dismutase, catalase and peroxidase) and a marked decline in reactive oxygen species (ROS) production in the mycelia. Moreover, MLT induced endogenous nitric oxide (NO) production during the culture. The NO donor sodium nitroprusside (SNP) potentiated MLT-induced inhibition of O2− production, but NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) enhanced O2− production, whereas MLT-induced NO level was increased by the ROS scavenger vitamin C (Vc). The changes in NO and H2O2 were proved to be involved in the MLT-induced downregulation of the expressions of HA biosynthetic genes, leading to the suppression of HA production. This study provides new insight into the regulatory roles of MLT on fungal secondary metabolism activities and a basis for understanding self-resistance in phototoxin-producing fungi.

Nitric oxide and long-term outcomes after kidney transplantation: Results of the TransplantLines cohort study

Impaired endogenous nitric oxide (NO) production may contribute to graft failure and premature mortality in kidney transplant recipients (KTR). We investigated potential associations of 24-h urinary NOx (NO3− + NO2−) excretion (uNOx) with long-term outcomes. uNOx was determined by HPLC and GC-MS in 698 KTR and in 132 kidney donors before and after donation. Additionally, we measured urinary nitroso species (RXNO) by gas-phase chemiluminescence. Median uNOx was lower in KTR compared to kidney donors (688 [393–1076] vs. 1301 [868–1863] before donation and 1312 [982–1853] μmol/24 h after donation, P < 0.001). During median follow-up of 5.4 [4.8–6.1] years, 150 KTR died (61 due to cardiovascular disease) and 83 experienced graft failure. uNOx was inversely associated with all-cause mortality (HR per doubling of uNOx: 0.84 [95% CI 0.75–0.93], P < 0.001) and cardiovascular mortality (HR 0.78 [95% CI 0.67–0.92], P = 0.002). The association of uNOx with graft failure was lost when adjusted for renal function (HR per doubling of uNOx: 0.89 [95% CI 0.76–1.05], P = 0.17). There were no significant associations of urinary RXNO with outcomes. Our study suggests that KTR have lower NO production than healthy subjects and that lower uNOx is associated with a higher risk of all-cause and cardiovascular mortality.

Recovery of hyperoxia‐induced DDAH1 suppression with FXR agonist GW4064 in human pulmonary microvascular endothelial cells

ObjectivePulmonary hypertension (PH) predicts mortality in patients with bronchopulmonary dysplasia (BPD), and chronic hyperoxia exposure contributes to BPD‐PH disease progression. BPD‐PH is characterized by aberrant pulmonary vascular wall proliferation/remodeling, which occludes the microvascular lumen, increasing pulmonary vascular resistance. Endogenous nitric oxide (NO) production by pulmonary vascular endothelial cells promotes apoptosis of pulmonary vascular endothelial and smooth muscle cells. In vitro studies of human pulmonary microvascular endothelial cells (hPMVEC) have shown that dimethylarginine dimethylaminohydrolase‐1 (DDAH1) promotes NO‐mediated apoptosis. DDAH1 metabolizes the majority of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of endothelial NO synthase. Therefore, our hypothesis is that pharmacologically enhancing DDAH1 expression in hPMVEC will restore endogenous endothelial NO production.MethodshPMVEC were grown at 37 ̊C to ~70% confluence. Farnesoid X receptor (FXR) agonist, GW4064 (1.25 µM) was used to bind FXR element (FXRE) of the DDAH1 promoter to enhance transcription. hPMVEC were pre‐treated with FXR agonist for 24 hours and then exposed to 85%O2 or 21%O2 for an additional 24 hours. DDAH1 protein expression was analyzed by Western blot. Groups were compared by 1‐way ANOVA.ResultsIn hPMVEC, hyperoxia exposure resulted in lower DDAH1 protein levels compared to hPMVEC grown in normoxia (N=6 in each group, p=0.003). Treatment with GW4064 prior to exposing to hyperoxia resulted in 4.3‐fold greater DDAH1 protein levels than in vehicle/85%O2 hPMVEC (N=6, p=0.044), and restored DDAH1 protein levels to 72% of that seen in the vehicle/21%O2exposed hPMVEC.ConclusionsChronic hyperoxia suppresses DDAH1 levels, and FXR agonist promotes DDAH1 recovery in hPMVEC. We speculate that promoting endogenous DDAH1 expression may prevent aberrant proliferation in the pulmonary vascular wall and thereby attenuate or prevent the vascular remodeling characteristic of pulmonary hypertension in BPD.

Endogenous nitric oxide contributes to chloride and sulphate salinity tolerance by modulation of ion transporter expression and reestablishment of redox balance in Brassica napus cultivars

Salinity is an adverse environmental stress for crop plants and the mechanism of salinity tolerance and its interaction with phytohormone like nitric oxide (NO) is still lacking, especially for Na2SO4 in B. napus. Therefore, in the present study, B. napus cultivars were grown under equimolar concentrations of NaCl/Na2SO4 and with their anions (KCl/K2SO4), to discriminate toxic responses of different types of salts on growth, oxidative stress, antioxidant defense, anion concentration and endogenous production of NO. Results showed that plant growth, photosynthetic rate and pigments productions were strongly inhibited under Na+ dominated salt treatments (NaCl/Na2SO4). As a result, production of oxidative stress (H2O2, O2.-, MDA, EL) related parameters were significantly induced under these treatments. The uptake of Na+ was high in B. napus cultivars irrespective of chloride/sulphate anions presence. However, Cl- and SO42- anions accumulation was only high in sensitive cultivars. The differential responses of B. napus cultivars against salinity treatments were associated with endogenous production of NO. The tolerant cultivar maintained higher level of NO, while sensitive cultivars experience a reduction in NO and inhibition of its biosynthesis enzymes, upon exposure to salinity treatments. To prove NO involvement, NO scavenger was applied on the leaves of B. napus cultivars, which significantly induced salt toxicity symptoms, oxidative stress and upregulated gene expression of ion transporters and uptake of Na+, Cl- and SO42-. Conversely, application of NO donor (sodium nitroprusside) reversed the salinity induce oxidative stress, ion accumulation and stimulated antioxidant defense in B. napus cultivars. Thus, the present study shows that endogenous NO level could act as an essential signaling molecule for triggering and activating the salinity adaptive response in rapeseed and Na+ toxicity plays a dominate role in growth inhibition, while the additive effect of chloride/sulphate anions may be cultivar dependent.

Melatonin promotes the normal cellular mitochondrial function of lotus seeds through stimulating nitric oxide production

Melatonin (MT) plays a vital role in diverse physiological processes of postharvest fruit and vegetables but information on the involvement of nitric oxide (NO) in the MT pathway is limited. The effect of NO, MT and MT combined with the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (MT + cPTIO) on the cellular mitochondrial function of lotus seeds was investigated. The browning of lotus seeds was delayed by NO and MT treatments but aggravated by cPTIO treatment. Reactive oxygen species in the mitochondria of NO and MT-treated seeds were efficiently scavenged by antioxidant enzymes stimulated by the treatment, thus inhibiting malondialdehyde production and oxidative damage of the mitochondria. The activities of energy metabolism-related enzymes involved in the respiratory chain were also increased by NO and MT treatments, thereby enhancing ATP production in the lotus seeds. This resulted in increased mitochondrial membrane potential and oxygen consumption during respiratory metabolism. However, the MT + cPTIO treatment produced the opposite effect to MT alone that increased NOS activity but showed no consistent effect on NR activity. These findings suggested that exogenous MT treatment maintained normal mitochondrial function in lotus seeds by inducing endogenous NO production, which could be resulted from the increased NOS activity.

Shared genetic liability and causal effects between major depressive disorder and insomnia.

Deciphering the genetic relationships between major depressive disorder (MDD) and insomnia may facilitate understanding biological mechanisms as well as inform more effective treatment regimens for these conditions. Here, we attempted to investigate mechanisms underlying relationships between MDD and insomnia in the context of shared genetic variations. Shared genetic variation was evaluated by polygenic analysis. In two-sample bidirectional Mendelian randomization (MR) analysis, causal relationships between MDD and insomnia were investigated; the list of shared genomic loci was identified using cross-trait meta-analysis. Putatively causal genes for the two diseases were prioritized by fine-mapping of transcriptome-wide associations. Polygenic analysis identified 15.1 thousand variants as causally influencing MDD, and 10.8 thousand variants as influencing insomnia. Among these variants, 8.5 thousand were shared between the two diseases. MR analysis suggests that genetic liability to MDD and to insomnia have mutual causal effects [MDD on insomnia with odds ratio (OR) = 1.25 and insomnia on MDD with OR = 2.23]. Cross-trait meta-analyses identified 89 genomic loci as being shared between MDD and insomnia, with some of them being prioritized as causal in subsequent fine-mapping of transcriptome-wide association signals. Analysis highlights possible role of endogenous production of nitric oxide in the brain, and the gonadotropic secretion in the pituitary as possibly physiological connectors of MDD and insomnia. Here, we show a substantial shared genetic liability and mutual causal links between MDD and insomnia. Presented findings provide novel insight into phenotypic relationship between these two interconnected conditions.