Low Concentrations Of Nitric Oxide Research Articles

Ultrahigh sensitive NO sensor based on WO3 film with ppb-level sensitivity

Nitric oxide (NO) is one of the hazardous gases which directly affect the vital organs of human beings. An accurate identification is essential for air quality assurance, environmental monitoring, automotive technology, and other industrial processes. Herein, we report nanostructured tungsten oxide (WO3) thin-film grown on SiO2 substrate under controlled oxidation conditions for NO sensing. The nanostructured-WO3 film's monoclinic phase has an average crystallite size of 12.89 nm, a lattice strain of 20.56, and an optical band gap of 2.89 eV. The fabricated device demonstrates high selectivity, stability, and faster response/recovery time with a sensor response of 1.26 for 100 ppb NO concentration, which increases to an ultra-high response (>25) for 1 ppm at 250 °C with a detection limit of ∼4 ppb. Ultrahigh response of the sensors is due to high specific surface area and effective gas diffusion ability, which lead to potential applications in low concentration NO detection.

Spectroscopic Characterization of a Diferric Mycobacterial Hemerythrin-Like Protein with Unprecedented Reactivity toward Nitric Oxide.

Hemerythrin-like proteins (HLPs) are broadly distributed across taxonomic groups and appear to play highly diverse functional roles in prokaryotes. Mycobacterial HLPs contribute to the survival of these pathogenic bacteria in mammalian macrophages, but their modes of action remain unclear. A recent crystallographic characterization of Mycobacterium kansasii HLP (Mka-HLP) revealed the unexpected presence of a tyrosine sidechain (Tyr54) near the coordination sphere of one of the two iron centers. Here, we show that Tyr54 is a true ligand to the Fe2(III) ion which, in conjunction with the presence of a μ-oxo group bridging the two iron(III), brings unique reactivity toward nitric oxide (NO). Monitoring the titration of Mka-HLP with NO by Fourier-transform infrared and electron paramagnetic resonance spectroscopies shows that both diferric and diferrous forms of Mka-HLP accumulate an uncoupled high-spin and low-spin {FeNO}7 pair. We assign the reactivity of the diferric protein to an initial radical reaction between NO and the μ-oxo bridge to form nitrite and a mixed-valent diiron center that can react further with NO. Amperometric measurements of NO consumption by Mka-HLP confirm that this reactivity can proceed at low micromolar concentrations of NO, before additional NO consumption, supporting a NO scavenging role for mycobacterial HLPs.

Exogenous Nitric Oxide Up-regulates the Runx2 Via Bmp7 Overexpression to Increase the Osteoblast Matrix Production In Vitro

Background: Nitric oxide (NO) is a signaling molecule that is required for the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). According to previous reports, high concentrations of sodium nitroprusside (SNP) inhibit the osteogenic differentiation of BMSCs, while its low concentration promotes this process. Objectives: The present investigation focused on evaluating the underlying mechanism of the osteogenic differentiation of BMSCs treated with low concentrations of SNP as an NO generating agent. Methods: The BMSCs after the 3rd passage was differentiated to osteoblasts when treated with 100 µM for 1 hour every 48 hours until 5, 10, 15, and 20 days of incubation. Then, the matrix production was estimated by quantitative alizarin red assay and calcium determination. The expression of different genes involved in osteogenic differentiation was statistically determined using the reverse transcriptase polymerase chain reaction. Finally, alkaline phosphatase activity was measured by a commercial kit. Results: The exogenous NO caused a significant (P<0.05) increase in the matrix production of differentiated BMSCs from day 5 to 20. The results showed the elevation of alkaline phosphatase activity and the up-regulation of its gene. Eventually, an increase was observed in the expression of a cascade of other genes such as osteonectin, Bmp7, Smad1, Runx2, and Raf1 in treated BMSCs. Conclusion: Overall, short-time treatment with a low concentration of exogenous NO increases the matrix production via gene up-regulation and protein production, which might open a new window in treating the low-density bone complication.

Mapping of the sGC Stimulator BAY 41-2272 Binding Site on H-NOX Domain and Its Regulation by the Redox State of the Heme.

Soluble guanylate cyclase (sGC) is the main receptor of nitric oxide (NO) and by converting GTP to cGMP regulates numerous biological processes. The β1 subunit of the most abundant, α1β1 heterodimer, harbors an N-terminal domain called H-NOX, responsible for heme and NO binding and thus sGC activation. Dysfunction of the NO/sGC/cGMP axis is causally associated with pathological states such as heart failure and pulmonary hypertension. Enhancement of sGC enzymatic function can be effected by a class of drugs called sGC “stimulators,” which depend on reduced heme and synergize with low NO concentrations. Until recently, our knowledge about the binding mode of stimulators relied on low resolution cryo-EM structures of human sGC in complex with known stimulators, while information about the mode of synergy with NO is still limited. Herein, we couple NMR spectroscopy using the H-NOX domain of the Nostoc sp. cyanobacterium with cGMP determinations in aortic smooth muscle cells (A7r5) to study the impact of the redox state of the heme on the binding of the sGC stimulator BAY 41-2272 to the Ns H-NOX domain and on the catalytic function of the sGC. BAY 41-2272 binds on the surface of H-NOX with low affinity and this binding is enhanced by low NO concentrations. Subsequent titration of the heme oxidant ODQ, fails to modify the conformation of H-NOX or elicit loss of the heme, despite its oxidation. Treatment of A7r5 cells with ODQ following the addition of BAY 41-2272 and an NO donor can still inhibit cGMP synthesis. Overall, we describe an analysis in real time of the interaction of the sGC stimulator, BAY 41-2272, with the Ns H-NOX, map the amino acids that mediate this interaction and provide evidence to explain the characteristic synergy of BAY 41-2272 with NO. We also propose that ODQ can still oxidize the heme in the H-NOX/NO complex and inhibit sGC activity, even though the heme remains associated with H-NOX. These data provide a more-in-depth understanding of the molecular mode of action of sGC stimulators and can lead to an optimized design and development of novel sGC agonists.

Electrocatalytic Reduction of Low-Concentration Nitric Oxide into Ammonia over Ru Nanosheets

Electrocatalytic Reduction of Low-Concentration Nitric Oxide into Ammonia over Ru Nanosheets

A Nanocoating Co-Localizing Nitric Oxide and Growth Factor onto Individual Endothelial Cells Reveals Synergistic Effects on Angiogenesis.

The delivery of nitric oxide (NO)-an intrinsic cellular signaling molecule-is promising for disease treatment, in particular to vascular diseases, due to its endothelial-derived inherent nature. The limited diffusion distance of labile NO prompts researchers to develop various carriers and targeting methods for specific sites. In contrast to the apoptotic effect of NO, such as anticancer, delivering low NO concentration at the desired targeting area is still intricate in a physiological environment. In this study, the layer-by-layer assembled nanocoating is leveraged to develop a direct NO delivery platform to individual endothelial cells (ECs). NO can be localized to individual ECs via S-nitrosothiol-bound polyacrylic acid which is a polymer directly providing an endothelial-like constant level of NO. To increase angiogenic activation along with NO, VEGF is additionally applied to specific receptors on the cell surface. Notably, the survival and proliferation of ECs are significantly increased by a synergistic effect of NO and VEGF co-localized via nanocoating. Furthermore, the nanocoating remarkably promoted cell migration and tubule formation-prerequisites of angiogenesis. The proposed unique technology based on nanocoating demonstrates great potential for conferring desired angiogenic functions to individual ECs through efficient NO delivery.

Abstract 11986: A Safety Study of Intermittent versus Continuous Inhaled NO Therapy in Spontaneously Breathing COVID-19 Patients: A Randomized Controlled Trial

Introduction: Nitric oxide (NO) inhalation (iNO) therapy has been approved as a salvage therapy in patients with acute respiratory distress syndrome. However, the optimal patterns of therapeutic administration and iNO efficacy in COVID-19 patients with hypoxemia have not been studied so far. Hypothesis: A combination of high-concentration intermittent iNO treatment with continuous low-concentration NO gas supplementation between therapeutic high-dose iNO sessions may be a safe approach in COVID-19 patients with hypoxemia compared with the high-dose spike therapy alone. Methods: A single-center randomized controlled trial examined the safety of administration of intermittent high-dose iNO therapy versus the intermittent therapy in the presence of continuous low-dose iNO in spontaneously breathing COVID-19 patients (www.clinicaltrials.gov #NCT04476992). The study comprised adult patients tested positive for the COVID-19 by RT-PCR, who required oxygen and was admitted to the respiratory hospital. After attrition, a total of 20 patients were enrolled and randomized to the group of intermittent high-dose iNO treatment combined with continuous low-dose NO supplementation (group 1) or the group of intermittent high-dose iNO treatment(group 2). Control group (group 3) comprised retrospective patients who received conventional treatment for COVID-19 in hospital. Results: Administration of intermittent high-dose iNO therapy combined with continuous low-dose NO supplementation significantly improved physiological interactions in the heart-lung blood circulation system and was not associated with the extrapulmonary organ dysfunction. Safety parameters are presented in Table 1. Conclusions: High-dose intermittent iNO therapy combined with continuous low-dose NO gas supplementation may be considered a safe adjuvant modality of treatment for COVID-19 in spontaneously breathing hypoxemic patients.

Delivery of Nitric Oxide in the Cardiovascular System: Implications for Clinical Diagnosis and Therapy.

Nitric oxide (NO) is a key molecule in cardiovascular homeostasis and its abnormal delivery is highly associated with the occurrence and development of cardiovascular disease (CVD). The assessment and manipulation of NO delivery is crucial to the diagnosis and therapy of CVD, such as endothelial dysfunction, atherosclerotic progression, pulmonary hypertension, and cardiovascular manifestations of coronavirus (COVID-19). However, due to the low concentration and fast reaction characteristics of NO in the cardiovascular system, clinical applications centered on NO delivery are challenging. In this tutorial review, we first summarized the methods to estimate the in vivo NO delivery process, based on computational modeling and flow-mediated dilation, to assess endothelial function and vulnerability of atherosclerotic plaque. Then, emerging bioimaging technologies that have the potential to experimentally measure arterial NO concentration were discussed, including Raman spectroscopy and electrochemical sensors. In addition to diagnostic methods, therapies aimed at controlling NO delivery to regulate CVD were reviewed, including the NO release platform to treat endothelial dysfunction and atherosclerosis and inhaled NO therapy to treat pulmonary hypertension and COVID-19. Two potential methods to improve the effectiveness of existing NO therapy were also discussed, including the combination of NO release platform and computational modeling, and stem cell therapy, which currently remains at the laboratory stage but has clinical potential for the treatment of CVD.

Preconditioning of bull semen with sub-lethal oxidative stress before cryopreservation: Possible mechanism of mitochondrial uncoupling protein 2

Preconditioning of sperm using sub-lethal oxidative stress before cryopreservation is an innovative approach that can improve sperm cryo-survival. Mitochondrial uncoupling proteins (UCPs) are critical in reducing ROS level during stress conditions. The aim of the current study was to investigate whether mild sub-lethal stress induced by low concentrations of nitric oxide and hydrogen peroxide has a protective effect on quality parameters of post–thaw bull semen through modulations of mitochondrial uncoupling protein 2 (UCP2) expression. Semen samples were collected from 6 mature Holstein bulls, then mixed and divided into 8 aliquots: fresh, frozen control and frozen groups treated with NO: 0.1 (NO-0.1), 1(NO-1), 10 μM (NO-10), and H2O2: 0.1(H2O2-0.1), 1(H2O2-1) and 10μM (H2O2-10). A significantly higher percentage of total motility, progressive motility and viability was observed in NO-1 and H2O2-10 compared to the other frozen groups (P < 0.05). Sperm exposed to 1 μM NO and 10μM H2O2 showed significantly increased percentages of mitochondria activity and membrane integrity (P < 0.05). Moreover, the lowest percentage of apoptotic percentage was observed in the NO-1 and H2O2-10 in comparison to the other frozen groups. In addition, the expression level of UCP2 was higher in the NO-1 and H2O2-10 compared to the other groups (P < 0.05). It can be concluded that stress preconditioning of bull sperm before cryopreservation can increase UCP2 expression of sperm, that can play a protective role against cryoinjury after thawing.

Atmospheric photo-oxidation of myrcene: OH reaction rate constant, gas-phase oxidation products and radical budgets

Abstract. The photo-oxidation of myrcene, a monoterpene species emitted by plants, was investigated at atmospheric conditions in the outdoor simulation chamber SAPHIR (Simulation of Atmospheric PHotochemistry In a Large Reaction Chamber). The chemical structure of myrcene consists of one moiety that is a conjugated π system (similar to isoprene) and another moiety that is a triple-substituted olefinic unit (similar to 2-methyl-2-butene). Hydrogen shift reactions of organic peroxy radicals (RO2) formed in the reaction of isoprene with atmospheric OH radicals are known to be of importance for the regeneration of OH. Structure–activity relationships (SARs) suggest that similar hydrogen shift reactions like in isoprene may apply to the isoprenyl part of RO2 radicals formed during the OH oxidation of myrcene. In addition, SAR predicts further isomerization reactions that would be competitive with bimolecular RO2 reactions for chemical conditions that are typical for forested environments with low concentrations of nitric oxide. Assuming that OH peroxy radicals can rapidly interconvert by addition and elimination of O2 like in isoprene, bulk isomerization rate constants of 0.21 and 0.097 s−1 (T=298 K) for the three isomers resulting from the 3′-OH and 1-OH addition, respectively, can be derived from SAR. Measurements of radicals and trace gases in the experiments allowed us to calculate radical production and destruction rates, which are expected to be balanced. The largest discrepancies between production and destruction rates were found for RO2. Additional loss of organic peroxy radicals due to isomerization reactions could explain the observed discrepancies. The uncertainty of the total radical (ROx=OH+HO2+RO2) production rates was high due to the uncertainty in the yield of radicals from myrcene ozonolysis. However, results indicate that radical production can only be balanced if the reaction rate constant of the reaction between hydroperoxy (HO2) and RO2 radicals derived from myrcene is lower (0.9 to 1.6×10-11 cm3 s−1) than predicted by SAR. Another explanation of the discrepancies would be that a significant fraction of products (yield: 0.3 to 0.6) from these reactions include OH and HO2 radicals instead of radical-terminating organic peroxides. Experiments also allowed us to determine the yields of organic oxidation products acetone (yield: 0.45±0.08) and formaldehyde (yield: 0.35±0.08). Acetone and formaldehyde are produced from different oxidation pathways, so that yields of these compounds reflect the branching ratios of the initial OH addition to myrcene. Yields determined in the experiments are consistent with branching ratios expected from SAR. The yield of organic nitrate was determined from the gas-phase budget analysis of reactive oxidized nitrogen in the chamber, giving a value of 0.13±0.03. In addition, the reaction rate constant for myrcene + OH was determined from the measured myrcene concentration, yielding a value of (2.3±0.3)×10-10 cm3 s−1.

Investigation on Protic Ionic Liquids as Physical Solvents for Absorption of NO at Low Pressures.

Nitric oxide (NO) absorption in ionic liquids (ILs) is an interesting issue, but little attention has been focused on the removal of NO at low partial pressures. Herein, a series of protic ionic liquids (PILs) based on polyamines as the cation and hydroxybenzenes as the anion were prepared for capturing low-concentration NO (0–0.6 bar). Triethylenetetramine phenolate ([TETAH][PhO]) showed an excellent absorption performance, with low viscosity, fast absorption rate, and high absorption capacity. The experimental solubility data were fitted by the Krichevsky–Kasarnovsky (K–K) equation, and the absorption enthalpy (ΔH) of NO in [TETAH][PhO] was thus calculated to be −43.60 kJ/mol. Density functional theory calculations were further performed to better understand the interaction of [TETAH][PhO] with NO on the molecular level, and the results suggest that the weak interaction of NO with the PIL was induced by the presence of H protons. It is believed that this work may provide a new method for the efficient and reversible absorption of low-concentration NO.

Tropospheric and stratospheric NO retrieved from ground-based Fourier-transform infrared (FTIR) measurements

Abstract. Nitric oxide (NO) is a key active trace gas in the atmosphere, which contributes to form harmful ozone in the troposphere and to the destruction of ozone in the stratosphere. In this study, we present the NO retrieval from ground-based Fourier-transform infrared (FTIR) solar absorption spectrometry measurements at a polluted site (Xianghe, China) and a background site (Maïdo, Reunion Island). The degree of freedom (DOF) of the NO retrieval is 2.3±0.4 (1σ) at Xianghe and 1.3±0.1 at Maïdo. By looking at the FTIR NO retrievals at Xianghe and Maïdo, we find that the stratospheric NO partial column is large in summer as compared to winter at both sites, and the seasonal variation in the FTIR stratospheric NO partial columns is consistent with that observed by the co-located Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) satellite measurements. A large diurnal variation in the stratospheric NO partial column is observed by the FTIR measurements at Maïdo, with an increase from the early morning to about 14:00 local time and a decrease thereafter. Due to the low NO concentration near the surface, the FTIR NO retrieval is only sensitive to the stratosphere at Maïdo. The high NO mole fraction near the surface at Xianghe allows us to derive tropospheric and stratospheric NO partial columns separately, although the tropospheric column is very difficult to retrieve in summer (June–August) because of the high water vapor abundance. A good correlation is found between the NO observed by the FTIR measurements and other air pollutants (NO2 and CO) in the troposphere at Xianghe. It is the first study of a successful analysis of NO in the troposphere from a ground-based FTIR site. The tropospheric and stratospheric NO retrieval might be possible at other potential FTIR sites inside or near large cities with enhanced levels of NO near the surface.

Near-infrared light triggered multi-mode synergetic therapy for improving antibacterial and osteogenic activity of titanium implants

Reducing bacterial infection and improving osseointegration are critical for the long-term use of orthopedic implants, especially for the infection related surgery. Here, mesoporous dopamine (MPDA) nanoparticles were loaded with nitric oxide (NO) donor, S-nitrosoglutathione (GSNO), and they were immobilized on the surface of titanium (Ti). When bacterial infections occurred, a large amount of NO was rapidly released and triggered by the thermal effect of MPDA after the near-infrared (NIR) light irradiation, which could damage the permeability and integrity of the bacterial membrane, leading to the leakage of bacterial DNA, proteins and ATP. Thus, bacteria was synergistically eliminated by NO and photothermal therapy (PTT) under NIR irradiation. While without NIR irradiation, the low concentration of NO was slowly released into the environment from GSNO, which promoted the proliferation and differentiation of osteoblasts. In addition, the in vivo results also demonstrated good osteogenic and antibacterial effects. Therefore, this study demonstrated a multi-mode synergetic therapy for promoting the antibacterial property and osseointegration of titanium implants.

Development of an electrochemical sensor for nitric oxide based on carbon paste electrode modified with Nafion, gold nanoparticles and graphene nanoribbons

Various physiological as well as pathophysiological processes in the cardiovascular system, in the immune response or in neurotransmission depend on changes of the concentration of nitric oxide (NO). Due to the instability of this ubiquitous signal molecule in vivo and in vitro, its rapid and direct detection is necessary to obtain meaningful results. Therefore, the development of a method for the rapid electrochemical detection of nitric oxide at 0.72 V (vs. Ag/AgCl) using a carbon paste electrode, modified by drop casting, is presented. As modifying solution, a nanocomposite consisting of Nafion, graphene nanoribbons, and gold nanoparticles was prepared. The voltammetric investigations with the optimized sensor were performed at room temperature in phosphate buffer solution (0.1 M, pH 7.4) as supporting electrolyte. Based on differential pulse voltammetry measurements, the obtained results for the analytical signal showed good linear response in the range of 0.39–2.34 μM and 2.34–104.7 μM with a correlation coefficient of 0.9941 and 0.9984, respectively. For both linear ranges, the repeatability as well as the reproducibility was <5% and <10%, respectively. A concentration of 40 nM was determined for the detection limit, whereas the limit of quantification was 130 nM. In addition, the influence of physiological interferences was also investigated and resulted in negligible effects. Finally, the sensor was successfully used to measure the NO release of NO donors. Based on the results obtained, the new sensor provides a simple and fast method for a direct voltammetric determination of low nitric oxide concentrations in solutions.

Phosphorylation of Akt at Thr308 regulates p-eNOS Ser1177 during physiological conditions.

Endothelial nitric oxide synthase (eNOS)‐derived nitric oxide (NO) plays a crucial role in maintaining vascular homeostasis. As a hallmark of eNOS activation, phosphorylation of eNOS at Ser1177 induced by activated protein kinase B (PKB/Akt) is pivotal for NO production. The complete activation of Akt requires its phosphorylation of both Thr308 and Ser473. However, which site plays the main role in regulating phosphorylation of eNOS Ser1177 is still controversial. The purpose of the present study is to explore the specific regulatory mechanism of phosphorylated Akt in eNOS activation. Inhibition of Akt Thr308 phosphorylation by a specific inhibitor or by siRNA in vitro led to a decrease in eNOS phosphorylation at Ser1177 and to lower NO concentration in the cell culture medium of HUVECs. However, inhibiting p‐Akt Ser473 had no effect on eNOS phosphorylation at Ser1177. Next, we administered mice with inhibitors to downregulate p‐Akt Ser473 or Thr308 activity. Along with the inhibition of p‐Akt Thr308, vascular p‐eNOS Ser1177 protein was simultaneously downregulated in parallel with a decrease in plasma NO concentration. Additionally, we cultured HUVECs at various temperature conditions (37, 22, and 4 °C). The results showed that p‐Akt Ser473 was gradually decreased in line with the reduction in temperature, accompanied by increased levels of p‐Akt Thr308 and p‐eNOS Ser1177. Taken together, our study indicates that the phosphorylation of Akt at Thr308, but not at Ser473, plays a more significant role in regulating p‐eNOS Ser1177 levels under physiological conditions.

Nitric Oxide Prodrug Delivery and Release Monitoring Based on a Galactose-Modified Multifunctional Nanoprobe.

Nitric oxide (NO)-based cancer therapy has attracted much attention in recent years owing to its broad effects on cancer. Low concentrations of NO stimulate cancer cell progression, while its higher levels induce cell apoptosis, and thus, it has motivated the development of probes for in situ NO release monitoring. In this work, a galactose-modified benzothiadiazole-based fluorescent probe (GalNONP/C) was synthesized as both a NO-responsive nanoprobe and NO prodrug carrier. The probe exhibited far-red emission in the range from 550 to 800 nm, and the response showed acidity preference. The galactose on the probe enabled selective targeting of hepatocellular carcinoma (HCC) cells by binding to the asialoglycoprotein receptor (ASGPR) on the cell surface. The probe also delivered low-molecular weight NO prodrug JS-K into cells and monitored the real-time release of the generated NO. Furthermore, in vivo NO imaging with tumor targeting was demonstrated in HCC orthotopic transplantation nude mice and liver sections. Compared with the control experiment using a probe without NO prodrug loading, higher fluorescence response of NO was detected in the cell (3.0 times) and liver slices of the HCC tumor model (2.7 times). This strategy may pave the way to develop nanoprobes for in situ NO monitoring and therapy evaluation in NO-related cancer therapy.

Highly Efficient and Reversible Absorption and Oxidation of Low-Concentration Nitric Oxide by Functionalized Ionic Liquids

A novel method of using anion-functionalized ionic liquids (ILs) with high NO absorption capacity and reversibility for the capture and in situ oxidation of low-concentration NO was established. For the mixed gas containing 0.25% NO, the accumulation rate of nitric acid in these ILs was significantly higher than that in the conventional ILs; after absorption and oxidation reached equilibrium, the molar ratio of HNO₃ to [P₄₄₄₆][PhSO₃] was 0.86, which was 5 times as high as that of the conventional IL. Therefore, the problems of low efficiency and poor reversibility of traditional ILs in the absorption and oxidation process were solved. Through absorption and oxidation experiments, quantum chemical calculation, NMR, and time-resolved in situ ATR-FTIR spectroscopic investigation, the results demonstrated that such a high accumulation rate of HNO₃ originated from high uptake of NO through multiple-site interaction. Moreover, high reversibility is attributed to low volatility of conjugated acid of anions and decreased basicity of O sites on anions. We believe that such highly efficient and reversible conversion of low-concentration NO to HNO₃ by ILs provides a new strategy for improving atomic economy of fossil fuel combustion, that is, converting post-combustion pollutants to good valuable chemicals.

The Effect of Doxorubicin and Exercise on the Formation of Nitric Oxide in Skeletal Muscle

Doxorubicin (DOX) is an effective anti-tumor agent which leaves patients with debilitating side effects such as fatigue and muscle weakness. The purpose of this study was to examine the influence of both DOX and acute exercise on the formation of nitric oxide (NO) in skeletal muscle. Thirty male rats were randomly assigned to 5 groups (A through E, n=6 per group). All rats received an intraperitoneal injection of 4.5 mg/kg DOX. Rats in group A and E did not perform any exercise and were sacrificed 24 and 48 hours post injection respectively. Groups B and C swam for 60 minutes 24 hours post injection, and were sacrificed at 25 and 48 hours respectively. Group D swam for 60 minutes at 24 and 48 hours post injection and were sacrificed at 49 hours. The red and white gastrocnemius, soleus and plantaris muscles were immediately excised at each end point. Overall, no differences (P>0.05) in NO levels were observed in any of the muscles between any of the groups. However, consistently lower NO concentrations were observed in all muscles in the exercised versus non-exercised groups. For example, NO concentration in the plantaris muscles were 18.4 ± 1.6, 17.5 ± 1.4 and 17.0 ± 1.3 μmol/mg in groups B, C and D respectively versus 31.5 ± 9.7 and 25.3 ± 4.5 μmol/mg for groups A and E respectively. These data suggest that acute exercise may play an important role in regulating NO metabolism post DOX administration, however exercise intensity and duration need to be better elucidated to maximize its effects.

Profile of new vascular damage biomarkers in middle-aged men with arterial hypertension

PurposeNormal endothelial function is important for the homeostasis of the cardiovascular (CV) system. The aim of the present study was to determine the profile of key parameters of endothelial dysfunction in middle-aged men that play a significant role in the functioning of endothelial vessels, which seems to be crucial for the early diagnosis of cardiovascular disorders. Materials and methodsThe study included 53 men, 20 with hypertension (HTN), 18 with HTN and related diseases, 15 healthy controls Apart from general testing (BMI, biochemical analysis, SBP, DBP), we used the Griess reaction to assess the total amount of nitric oxide (NO), and used ELISA to verify the concentrations of malondialdehyde (MDA), nitrotyrosine (NT), asymmetric dimethylarginine (ADMA), tumor necrosis factor-alpha (TNF-α), monocyte chemotactic protein 1 (MCP-1), and myeloperoxidase (MPO). Furthermore, we assessed the concentration of circulating free DNA (cfDNA) using the fluorescence method. ResultsThe values of MDA, ADMA, cfDNA, and MPO observed in samples from men with HTN were determined to be higher compared to those from men without HTN. In the group of men with HTN and other concomitant cardiovascular disorders, we observed low concentrations of NO, MDA, and ADMA with high concentrations of cfDNA. ConclusionsThe results obtained for parameters selected for the study, should be considered by cardiologists as a prompt to include in the diagnostic profile the assessment of NO and cfDNA concentrations for risk evaluation and/or diagnosis of endothelial dysfunction in patients suffering from HTN or related complications.

Recent evidence for multifactorial biofilm regulation by heme sensor proteins NosP and H-NOX.

Heme is involved in signal transduction by either acting as a cofactor of heme-based gas/redox sensors or binding reversely to heme-responsive proteins. Bacteria respond to low concentrations of nitric oxide (NO) to modulate group behaviors such as biofilms through the well-characterized H-NOX family and the newly discovered heme sensor protein NosP. NosP shares functional similarities with H-NOX as a heme-based NO sensor; both regulate two-component systems and/or cyclic-di-GMP metabolizing enzymes, playing roles in processes such as quorum sensing and biofilm regulation. Interestingly, aside from its role in NO signaling, recent studies suggest that NosP may also sense labile heme. In this Highlight Review, we briefly summarize H-NOX-dependent NO signaling in bacteria, then focus on recent advances in NosP-mediated NO signaling and labile heme sensing.