Measurement Of Nitric Oxide Levels Research Articles

Prolonged Door-to-Balloon Time Leads to Endothelial Glycocalyx Damage and Endothelial Dysfunction in Patients with ST-Elevation Myocardial Infarction.

Damage to the endothelial glycocalyx (eGC) has been reported during acute ischemic events like ST-elevation myocardial infarction (STEMI). In STEMI, a door-to-balloon time (D2B) of <60 min was shown to reduce mortality and nonfatal complications. Here, we hypothesize that eGC condition is associated with D2B duration and endothelial function during STEMI. One hundred and twenty-six individuals were analyzed in this study (STEMI patients vs. age-/sex-matched healthy volunteers). After stimulating endothelial cells with patient/control sera, the eGC's nanomechanical properties (i.e., height/stiffness) were analyzed using the atomic force microscopy-based nanoindentation technique. eGC components were determined via ELISA, and measurements of nitric oxide levels (NO) were based on chemiluminescence. eGC height/stiffness (both p < 0.001), as well as NO concentration (p < 0.001), were reduced during STEMI. Notably, the D2B had a strong impact on the endothelial condition: a D2B > 60 min led to significantly higher serum concentrations of eGC components (syndecan-1: p < 0.001/heparan sulfate: p < 0.001/hyaluronic acid: p < 0.0001). A D2B > 60 min led to the pronounced loss of eGC height/stiffness (both, p < 0.001) with reduced NO concentrations (p < 0.01), activated the complement system (p < 0.001), and prolonged the hospital stay (p < 0.01). An increased D2B led to severe eGC shedding, with endothelial dysfunction in a temporal context. eGC components and pro-inflammatory mediators correlated with a prolonged D2B, indicating a time-dependent immune reaction during STEMI, with a decreased NO concentration. Thus, D2B is a crucial factor for eGC damage during STEMI. Clinical evaluation of the eGC condition might serve as an important predictor for the endothelial function of STEMI patients in the future.

Changes in the Oral Cavity Mucosal Surface under the Influence of Wearing Protective Face Masks—Nitric Oxide Concentration Analysis—Preliminary Report

Orders to cover the mouth and nose were introduced as a prophylaxis for COVID-19. The use of face masks, apart from their benefits, has some side effects. It can affect, among other things, the oral cavity mucosa, manifested by its dryness, and can increase the amount of inflammatory markers, for example, nitric oxide (NO). The aim of this research was to determine changes in the oral cavity mucosal surface under the influence of the use of protective face masks based on an innovative measurement of NO levels in the exhaled air of healthcare workers. The people taking part in this study were dental assistants and recorders who used masks during work. The first measurement of NO was carried out before starting work and putting on a mask, and the second measurement was carried out after work. Based on the research, a statistically significant difference was shown in the NO values before putting on a mask and immediately after removing it. Despite the advantages of wearing protective masks, studies have shown that their long-term use has an impact on the oral cavity mucosa, which is reflected in the higher level of NO in exhaled air.

Spectroscopic measurement of cortical nitric oxide release induced by ascending activation

The transition from sleep to the awake state is regulated by the activation of subcortical nuclei of the brainstem (BS) and basal forebrain (BF), releasing acetylcholine and glutamate throughout the cortex and inducing a tonic state of neural activity. It has been suggested that such activation is also mediated by the massive and diffuse cortical release of nitric oxide (NO). In this work we have combined the spectroscopic measurement of NO levels in the somatosensory cortex of the cat through its marker methemoglobin, as well as two other hemodynamic markers (oxyhemoglobin – oxyHb – and deoxyhemoglobin – deoxyHb), together with the electrical stimulation of BS and BF – to induce an experimental transition from a sleep-like state to an awake-like mode. The results show an increase of NO levels either after BS or BF activation. The response induced by BS stimulation was biphasic in the three studied markers, and lasted for up to 30s. The changes induced by BF were monophasic lasting for up to 20s. The systemic blockade of NO production abolished the observed responses to BS whereas responses to BF stimulation were much less affected. These results indicate a crucial role for NO in the neuronal activation induced by the ascending systems.

Effect of glucocorticoids on nasal polyposis, with detection of inflammatory response by measurement of nitric oxide levels in nasal polyp tissue

To investigate endoscopic staging, and nitric oxide levels in the polyp tissue, in patients with nasal polyposis undergoing glucocorticoid therapy. Nasal polyposis was evaluated using endoscopic staging and measurement of polyp tissue nitric oxide levels (chemiluminescence method). Forty-five nasal polyposis patients received either nasal therapy (n = 15), oral therapy (n = 15) or combined therapy (n = 15). Pre-treatment and post-treatment staging and nitric oxide levels were evaluated. Endoscopic grading indicated significant post-treatment staging improvements in the oral (p = 0.016) and combined (p = 0.016) groups. Post-treatment staging differed significantly between the three groups (p = 0.041), with greater improvements in the oral and combined groups. All groups showed significantly lower post-treatment nitric oxide levels, compared with baseline, but post-treatment levels did not differ significantly between groups. A significant association was found between treatment response and nitric oxide level alteration. This study demonstrates the favourable effects of glucocorticoids on nasal polyposis, and alteration in nitric oxide tissue levels post-treatment. Nitric oxide level in nasal polyp tissue could be an indicator of treatment response, and may aid surgical decision-making by detecting cases that probably will not respond to medical treatment.

Measurement of Nitric Oxide and Reactive Oxygen Species in the Vascular Wall

Vascular generation of nitric oxide (NO) plays an important role in the regulation of blood flow, and is counterbalanced by the formation of radical oxygen species (ROS). Thus, an imbalance in vascular NO and ROS production contributes to endothelial dysfunction, which is associated with cardiovascular disease. Here we review the main and commonly used methods that have been applied to determine vascular NO and ROS. Only NO microsensors, electron spin resonance (ESR), and NO sensitive fluorescent probes allow real time measurement of NO levels in cell suspensions, cell cultures, and isolated vascular segments in vitro, and of these techniques only NO microsensors have so far been developed for real time detection of NO in vivo. ROS formation has been detected in cell cultures by lucigenin- enhanced fluorescence, fluorescent probes e.g. 2',7'-dichlorodihydrofluorescein and dihydroethidium, by use of ESR, and also by electrochemical detection. The limitations of the electrochemical microsensors include interference from other substances, physical force on the sensors, and influence of temperature and changes in pH that may lead to artifactual changes in current. Therefore, specificity testing and calibration are pivotal, and in case of ROS, application of more than one technique is recommendable. Technical advances have allowed simultaneous detection of both NO and superoxide anion by use of electrochemical microsensors. Miniaturizing the sensors may also allow incorporation of those in lab-on- a-chip and may lead to real time measurements of NO and ROS in the coronary circulation in situ, and hence provide direct evaluation of endothelial and vascular function in cardiovascular disease.

Endothelial Nitric Oxide Synthase Gene Polymorphisms and the Risk of Diabetic Nephropathy in Type 2 Diabetes Mellitus

Endothelial dysfunction plays an important role in the pathogenesis of diabetic vascular disease, including diabetic nephropathy (DN). Endothelial nitric oxide synthase (eNOS) gene polymorphisms that affect eNOS activity are associated with endothelial dysfunction. The aim of this study was to evaluate the association of three polymorphisms of the eNOS gene (894G>T, -786T>C, and 27-bp-VNTR) with the risk of DN among type 2 diabetic patients. A total of 400 type 2 diabetic patients were enrolled in this study. The DN group comprised 200 patients; the group of diabetics without nephropathy comprised another 200 patients. Genetic analysis for eNOS gene polymorphisms was done in all subjects. Measurement of nitric oxide levels was estimated. The C allele for -786T>C and the T allele for 894G>T were significantly more frequent in diabetics with nephropathy than in diabetics without nephropathy (p<0.001; odds ratio [OR] and 95% confidence interval [CI] for the C allele=1.64 [1.24-2.17] and p<0.001; OR and 95% CI=1.7 [1.27-2.26] for the T allele). The haplotypes CTa (with all the mutant alleles) and CTb were significantly more common in patients with DN (p=0.01 and 0.003, respectively). These results suggested that the eNOS polymorphisms might represent genetic determinants for developing DN in type 2 diabetic Egyptians.

Acoustic rhinometry, spirometry and nitric oxide in relation to airway allergy and smoking habits in an adolescent cohort

Objective This study aimed to analyze upper and lower airway function and the impact of smoking habits in a cohort of allergic and healthy adolescents. The influence of smoking habits on the outcomes of rhinitis and asthma is well documented, but only few reports are available showing smoke related upper airway impairment by rhinometric measurements, and none with focus on early changes in adolescents. Methods A cohort followed from infancy was re-examined at the age of 18 years concerning allergy development. Acoustic rhinometry (VOL2), spirometry (FEV 1) and measurements of nitric oxide levels from the upper (nNO) and lower airways (eNO) were performed before and after physical exercise, and smoking habits were registered. Results Active smoking habits were reported by 4/21 subjects suffering from allergic rhinitis, by 1/4 from probable allergic rhinitis, by 0/3 subjects with atopic dermatitis and by 2/10 healthy controls. Smoking habits were reported as daily by 2 and occasional by 5 of the 7 active smokers. VOL2 did not increase in smokers after exercise as in non-smokers, resulting in a post-exercise group difference (7.3 ± 1.1 cm 3 vs. 8.8 ± 1.5 cm 3; p = 0.02), and FEV 1 values were lower in smokers compared to non-smokers (89 ± 7% vs. 98 ± 8%; p = 0.02). The nNO and eNO levels were, however, only slightly reduced in smokers. Airway allergy was discerned only in subjects with current allergen exposure by increased eNO levels compared to healthy controls (41 ± 44 ppb vs. 13 ± 5 ppb). The levels of VOL2, nNO and FEV 1 did not differentiate allergic subjects from healthy controls. Conclusions Low levels of tobacco smoke exposure resulted in reduced airway functions in this adolescent cohort. Acoustic rhinometry and spirometry were found to be more sensitive methods compared to nitric oxide measurements in early detection of airway impairment related to smoke exposure. A possible difference in airway vulnerability between allergic and healthy subjects due to smoke exposure remains to be evaluated in larger study groups.

Exhaled nitric oxide levels in infants with chronic lung disease.

Chronic lung disease (CLD) is an inflammatory disorder; in patients with other inflammatory disorders exhaled nitric oxide (NO) levels are elevated. The aim of this study was to test the hypothesis that prematurely born infants with CLD would have elevated exhaled NO levels compared to those without CLD and healthy term-born infants. Ten infants with CLD (median gestational age 26 weeks; CLD group), ten infants without CLD (median gestational age 32 weeks; non-CLD group) and ten term-born infants (term group) were examined at post-conceptional ages between 36 and 45 weeks. NO levels were measured during spontaneous tidal breathing. A facemask was positioned over the infant's nose and mouth and a sampling catheter was inserted through a small leak-free valve into the facemask. To measure nasal NO, the tip of the sampling catheter was placed in the nasal space and to measure facemask NO, the catheter tip was positioned inside the facemask at the infant's lips. Nasal compared to facemask NO levels were higher in all three groups (CLD; non-CLD; term: P=0.017, P=0.012 and P=0.017, respectively). The CLD group had higher peak nasal and facemask NO levels than the non-CLD ( P=0.011 and P=0.034 respectively) and the term ( P=0.005 and P=0.01 respectively) infants. Regression analysis demonstrated that facemask NO levels were significantly related to CLD, independent of gestational, post-natal and post-conceptional age ( P=0.006). our results suggest that exhaled nitric oxide levels are elevated in chronic lung disease infants. Facemask measurement of nitric oxide levels might be a potentially useful method to monitor infants with chronic lung disease.

Nitric Oxide-Mediated Cortical Activation: A Diffuse Wake-Up System

Nitric oxide (NO) has been implicated in some of the central pathways engaged in the regulation of the sleep-wake cycle. The existence of nitric oxide synthase (NOS) in the cholinergic basal forebrain (BF) cells projecting to the cortex suggests a role for NO in the activation induced by the BF during arousal. We tested, in the anesthetized cat, the hypothesis that inhibition of NOS would decrease the ability of BF cholinergic fibers to induce cortical activation. In control conditions, BF stimulation evoked an awake-like EEG pattern (i.e., a decrease in the low-frequency-high-amplitude oscillatory activity and an increase in the high-frequency-low-amplitude activity). After blocking NOS activity, the capacity of BF stimulation to induce cortical activation was strongly impaired. Furthermore, voltammetric measurements of NO levels revealed an increase in cortical NO after BF stimulation, also blocked by systemic NOS inhibition. These results indicate that the blockade of NOS activity significantly reduces the ability of BF stimulation to induce changes in the EEG pattern and suggest a role for NO in the BF-cholinergic system implicated in arousal mechanisms.

Nasal nitric oxide.

Nasal nitric oxide.

Effects of l-arginine treatment on symptoms and bladder nitric oxide levels in patients with interstitial cystitis

Objectives. Nitric oxide (NO) is involved in host defense reactions, and NO production is elevated in various inflammatory disorders. We have found very high levels of luminal NO in the urinary bladder of patients with interstitial cystitis. Oral treatment with low doses of l-arginine, the substrate for NO production, has been reported to alleviate symptoms in patients with interstitial cystitis. The aim of our investigation was to evaluate the effect of higher doses of l-arginine in patients with interstitial cystitis and to study the effects of l-arginine on NO production in the bladder. Methods. Nine women (age 69 ± 3 years) with interstitial cystitis were treated daily with 3 or 10 g of l-arginine for 5 weeks. Symptoms were evaluated with an interstitial cystitis symptom score index, and NO production was measured. Patients with stress incontinence (n = 18) were used as control subjects for measurement of NO levels. Results. NO concentration in the urinary bladder was markedly elevated in the patients with interstitial cystitis (239 ± 60 ppb) compared with the control patients (15 ± 2 ppb). NO levels did not change in the patients with interstitial cystitis after oral treatment with l-arginine (189 ± 72 ppb). There was no significant change in the symptom scores at either dose after 5 weeks of l-arginine treatment. Conclusions. l-arginine treatment in the doses used in this study did not change NO production in the urinary bladder in patients with interstitial cystitis. Furthermore, the patients in our study did not notice any relief of their symptoms.

Water vapour and carbon dioxide decrease nitric oxide readings.

Measurement of nitric oxide levels in exhaled air is commonly performed using a chemiluminescence detector. However, water vapour and carbon dioxide affect the chemiluminescence process. The influence of these gases at the concentrations present in exhaled air, has not yet been studied. For this in vitro study, mixtures of 50, 100 and 200 parts per billion (ppb) NO in air were prepared and fed into the NO analyser either directly or bubbled through water. Mixtures with CO2 were prepared by adding 0-10% CO2 to the diluent air. We found a significant decrease in NO readings in the water-saturated samples compared to the dry gas (p < 0.001), strongly dependent on the partial pressure of water. NO levels in exhaled air (mean 10 +/- 2 ppb) showed a decrease of 17 +/- 3% when water vapour was not absorbed. From the experiments with CO2 we found a decrease in NO reading of 1.04 +/- 0.07% per volume CO2 (%). Presence of water vapour, thus, leads to a systematic underestimation of NO levels. Insertion of a water absorber might, therefore, be advantageous. The influence of CO2 concentrations in the normal respiratory range is negligible. With high expiratory CO2 levels as applied in permissive hypercapnia, the effects may be substantial.

Interleukin-10 stimulation of endogenous nitric oxide release from human saphenous veins diminishes immunocyte adherence.

Interleukin-10 (IL-10) is described as a cytokine that exerts immune downregulating actions. In this regard, our study indicates that IL-10 activity on human saphenous veins is coupled to nitric oxide (NO) release. We demonstrated this phenomenon by using in vitro real-time amperometric measurement of NO levels in explanted human saphenous veins after IL-10 exposure. IL-10-induced NO release can inhibit the adherence of monocytes (75.7 +/- 15 cells/600 microm2 of endothelial surface) and granulocytes (65 +/- 18 cells/600 microm2 of endothelial surface) from control values (250-300 cells/600 microm2 of endothelial surface; p < 0.005). This inhibition is directly sensitive to NO synthase inhibition. The specificity of the IL-10 effects is shown by its sensitivity to antibody. In vivo measurement of IL-10 levels during and after cardiopulmonary bypass surgery indicated that they are higher at 6 h after skin closure (1,400 pg/ml) compared with levels found during surgery (300 pg/ml). We surmise that the postsurgical increase of IL-10 levels may be an immunoregulatory attempt to downregulate the diffuse inflammation that has been shown to be associated with cardiopulmonary bypass surgery.

Hyperdynamic circulation in patients with cirrhosis: direct measurement of nitric oxide levels in hepatic and portal veins

Background/Aims: Peripheral vasodilation represents the main vascular dysfunction associated with the hyperdynamic circulation of liver cirrhosis. This study was intended to measure directly regional and systemic levels of nitric oxide, a potent vasorelaxing mediator, in order to assess its role in the development of hemodynamic changes of cirrhosis. Methods: We compared nitric oxide levels in the splanchnic and systemic circulation of 25 patients with cirrhosis undergoing transjugular intrahepatic portosystemic stent shunt and in the hepatic vein and peripheral blood of 10 patients without cirrhosis submitted to venous catheterization. Nitric oxide levels were measured through electron paramagnetic resonance spectroscopy as nitrosylhemoglobin complexes. Results: Significantly higher nitric oxide levels were calculated in patients with cirrhosis with respect to controls, both in the peripheral and hepatic veins. In patients with cirrhosis, nitric oxide levels in the portal vein (3.44±2.17, expressed in arbitrary units) were higher than in the systemic circulation (1.89±1.15), but lower than in the hepatic vein (4.75±2.53; p<0.001 by variance analysis). Conclusions: These data suggest that nitric oxide synthetic pathway activity as well as nitric oxide release are enhanced at the level of splanchnic vasculature and, more important, in the hepatic tissue, confirming evidence of the predominant role of nitric oxide in the pathogenesis of hemodynamic changes in patients with cirrhosis with portal hypertension.