Oxide Production In Patients Research Articles

Metformin has no impact on nitric oxide production in patients with pre-diabetes

Aims/IntroductionThe authors evaluated the impact of different dose of metformin on NO (nitric oxide) production in subjects with pre-diabetes. Materials and MethodsThe metformin-naïve patients from one Diabetic Center with newly diagnosed pre-diabetes, without cardio-vascular diseases, were randomized (based on the identification number, individual for each inhabitant in the country) for treatment with different doses of metformin (group A 3 × 500 mg, group B 3 × 1000 mg) for 12 weeks. Then, the subjects from group B were switched to dose 3 × 500 for the last 3 weeks. The wide panel of L-arginine/NO pathway metabolites concentrations was assessed using the liquid chromatography-mass spectrometry technique. ResultsBetween October 2017 and December 2018, 36 individuals were initially randomized to intervention groups. The study was completed with 25 subjects: 14 patients in group A, 11 in group B; also 11 healthy volunteers were recruited. There was no difference between participants with pre-diabetes and healthy volunteers as regards the baseline characteristics except for fasting glucose and fatty liver. The decrease of L-citrulline concentration only was reported for treatment groups during the intervention period, with no change for the other NO-production related substances. ConclusionIt was the first study on the in vivo release of NO in humans with different metformin doses in patients with pre-diabetes. Metformin did not seem to increase NO production measured by the citrulline plasma levels, irrespective of the dose. The citrulline concentration change might indicate the drug impact on the condition of the enterocytes.

Extended nitric oxide analysis in patients with chronic rhinosinusitis with nasal polyps, with or without associated asthma

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a complex inflammatory disease highly impacting patient’s quality of life, and associated with lower airway inflammation often evolving into asthma. Exhaled nitric oxide (FENO) is a non-invasive tool to assess Type 2 airway inflammation and its extended analysis allows to differentiate between alveolar concentration (CalvNO) and bronchial output (JawNO). It is also possible to assess the sino-nasal production of nitric oxide (nNO). We studied extended nitric oxide production in patients with CRSwNP with or without associated asthma. Consecutive adult patients with CRSwNP, with or without asthma, and 15 healthy controls were enrolled. Exclusion criteria were: smoking, uncontrolled asthma, recent upper or lower airway infections and oral corticosteroid therapy in the 4 weeks preceding clinical evaluation. Patients’ demographic and clinical data were collected; patients underwent pulmonary function tests and extended nitric oxide analysis including nasal nNO assessment. A total of 125 subjects were enrolled (15 healthy controls; 69 with CRSwNP and asthma, and 41 with CRSwNP only). FENO, JawNO and CalvNO values were higher, while nNO was lower, in all patients with CRSwNP compared to healthy controls; no difference was found in CalvNO between patients with concomitant asthma and non-asthmatic subjects; in asthmatic patients, FENO and JawNO were significantly higher, while nNO values was lower, compared to patients with CRSwNP only. These results suggest that CRSwNP could be the first manifestation of a more complex systemic inflammatory pathology driven by Type 2 inflammation. An ‘inflammatory gradient’ hypothesis could describe a pattern of inflammation in CRSwNP patients that starts distally in the alveoli. Finally, our study indirectly reinforces the concept that novel biological drugs could become valid therapeutic options for nasal polyposis.

Plasma Asymmetric Dimethylarginine Levels in Neonates with Bronchopulmonary Dysplasia Associated with Pulmonary Hypertension

Background: Bronchopulmonary dysplasia (BPD) continues to be an important problem in neonates especially premature infants despite improved facilities of care, monitoring and treatment. Pulmonary hypertension (PH) is a major complicating factor and key cause of mortality in this population. Altered vascular and alveolar growth particularly in canalicular and early saccular stages of lung development following mechanical ventilation and oxygen therapy result in arrest of the lung development leading to BPD with PH. Early recognition of PH in infants with these risk factors is important for optimal management. We tested the hypothesis that asymmetric dimethylarginine, would be greater in infants with bronchopulmonary dysplasia associated pulmonary hypertension than in infants with BPD alone. The Aim: The aim of the current study was to measure the Asymmetric dimethylarginine (ADMA) levels, arginine levels & the plasma arginine-to-ADMA ratio in newborn infants with broncho-pulmonary dysplasia, to evaluate echocardiographic parameters among neonates with bronchopulmonary dysplasia, to correlate between plasma ADMA & arginine-to-ADMA ratio and echocardiographic (ECHO) parameters in those patients and to compare full term & preterm neonates with bronchopulmonary dysplasia as regard to plasma ADMA level. Methods: A case-control study was carried out of ninety (90) newborns selected from those admitted to Neonatal Intensive Care Unit at Maternity & Children Hospital and Alzhraa University hospital during the period from October 2015 to March 2018. Neonates were divided into 2 groups: Patient with BPD with PH (cases group): It included 45 neonates with BPD & PH, 35 preterm neonates and 10 full term neonates. Patient with BPD only (Control group): It included 45 neonates with BPD without PH. These 45 neonates were divided as 22 preterm neonates and 23 full term neonates. Laboratory work was done in Alzhraa University hospital. Asymmetric dimethylarginine (ADMA) levels & arginine levels were measured using competitive enzyme linked immune-assay (ELISA). Results: Patients with both BPD and PH had greater plasma levels of ADMA than patients with BPD alone (P value 0.000). ADMA level > 186 ng/dl can predict development of PH in patient with BPD with sensitivity 100% and specify 100%. Preterm neonates with BPD had greater level of ADMA than full term neonates (P value 0.002). There was no statically significance difference between level of ADMA if withdrawn before or after 28 days of age (range of age at time of sampling in our study was 23 - 40 days) (P value 0.878), even ADMA level increased above the cut point early in the disease before we screened some cases by ECHO. There was no statically significance difference between level of arginine in cases and control groups with P value 0.530. The plasma arginine-to-ADMA ratio was lower in cases than in controls suggesting a greater likelihood of inhibition of nitric oxide production in patients with both BPD and PH than in patients with BPD alone (P value 0.000). ADMA level can predict severity of pulmonary hypertension in patient with BPD, as it was positively correlated with the grade of pulmonary hypertension (P value 0.006). ADMA level is higher in neonates with BPD and PH who died than those who survived; it can predict death in neonates with BPD &PH at cut off point > 643 ng/dl. Conclusion: ADMA increased in newborn infants with BPD, who developed PH. ADMA may have diagnostic and prognostic values. ADMA level was higher in preterm neonates than full term neonates and its level was correlated positively with severity of PH. ADMA levels were significant higher in infants with BPD with PH who died later than those who survived. There was no statically significance difference between levels of ADMA, whether it was drawn before or after 28 days of age (range 23 - 40 days). Echocardiographic screening and ADMA measurement could help in prevention of PH, diagnosis and early treatment of newborn infants suffering from BPD.

Plasma Asymmetric Dimethylarginine Levels Are Increased in Neonates with Bronchopulmonary Dysplasia-Associated Pulmonary Hypertension

To test the hypothesis that levels of the endogenous inhibitor of nitric oxide production, asymmetric dimethylarginine (ADMA), would be greater in preterm infants with bronchopulmonary dysplasia (BPD)-associated pulmonary hypertension (PH) than in infants with BPD alone. A case-control study of 23 patients with both BPD and PH (cases) and 95 patients with BPD but no evidence of PH (controls). Levels of ADMA were compared between cases and controls by t test. Patients with both BPD and PH had greater plasma levels of ADMA than patients with BPD alone (P = .04). In samples drawn before 28 days of life, greater levels of ADMA were again found in cases compared with controls (P = .02). The plasma arginine-to-ADMA ratio was lower in cases than in controls (P = .03), suggesting a greater likelihood of inhibition of nitric oxide production in patients with both BPD and PH than in patients with BPD alone. In this neonatal BPD cohort, ADMA levels are increased in patients with BPD who develop PH. We speculate that ADMA may be both a biomarker and a potential therapeutic target for preterm infants with BPD-associated PH.

Association Analysis for Neuronal Nitric Oxide Synthase Gene Polymorphism with Plasma Nitrite/Nitrate Concentration in Schizophrenia

Summary Background: Single nucleotide polymorphisms (SNP) of many genes, including the gene for neuronal nitric oxide syn-thase (NOS1), were found significantly associated with schizo-phrenia. According to our previously published results of increased plasma nitric oxide concentration in patients with schizophrenia, we hypothesized that the NOS1 gene polymorphism might be a cause of increased nitric oxide production in patients with schizophrenia and tested the interdependence between plasma nitrite/nitrate concentrations and SNP (a CT transition located in exon 29) of the human NOS1 gene. Methods: Nitrite/nitrate concentration was measured in blood plasma of 38 patients with schizophrenia and of 39 age and gender matched healthy persons by the colorimet-ric test. The NOS1 gene polymorphism was determined by polymerase chain reaction analysis. Results: A significantly higher plasma nitrite/nitrate concentration was found in patients with schizophrenia (97.5±33.3 μmol/L, p<0.001) in comparison with controls (61.4±18.9 μmol/L). No T/T genotype was found in healthy individuals and there was a significant difference in the genotype distribution between patients and controls (χ2=24.54, p=0.0000047). Furthermore, a significant difference in the allele frequencies between patients and controls (χ2=19.00, p<0.000013, OR=4.45, 95% CI=2.12–9.39) was noted. Also, a significant difference in plasma nitrite/nitrate concentration was observed between patients having the C/T genotype (99.97±33.83 μmol/L) and the corresponding control (C/T) subgroup (63.88±10.26 μmol/L, p<0.01). However, there were no significant differences in nitrite/nitrate concentration between the patient subgroups with different genotypes (C/C, C/T, T/T). Conclusions: CT transition located in exon 29 of the human NOS1 gene may be responsible for the increased plasma nitrite/nitrate levels.

Clinical presentation, lipid peroxidation intensity, and features of nitric oxide production in patients with erysipelas

Clinical presentation, lipid peroxidation intensity, and features of nitric oxide production in patients with erysipelas

Cytokine Expression in Patients with Bladder Pain Syndrome/Interstitial Cystitis ESSIC Type 3C

Bladder wall nitric oxide production in patients with bladder pain syndrome type 3C is increased compared to undetectable nitric oxide in patients with nonHunner bladder pain syndrome and healthy controls. However, the underlying mechanism/s of the increased nitric oxide production is largely unknown. We compared mRNA expression of a select group of cytokines in patients with bladder pain syndrome/interstitial cystitis type 3C and in pain-free controls. Cold cup biopsies from 7 patients with bladder pain syndrome type 3C and 6 healthy subjects were analyzed. mRNA expression of IL-4, 6, 10 and 17A, iNOS, TNF-α, TGF-β and IFN-γ was estimated by real-time polymerase chain reaction. IL-17 protein expression was determined by immunohistochemistry. Mast cells were labeled with tryptase to evaluate cell appearance and count. IL-6, 10 and 17A, and iNOS mRNA levels as well as the number of mast cells infiltrating the bladder mucosa were significantly increased in patients withbladder pain syndrome type 3C compared to healthy controls. TNF-α, TGF-β and IFN-γ mRNA levels were similar in patients and controls. IL-17A expression at the protein level was up-regulated and localized to inflammatory cells and urothelium in patients with bladder pain syndrome type 3C. Patients with bladder pain syndrome/interstitial cystitis had increased mRNA levels of IL-17A, 10 and 6, and iNOS. IL-17A might be important in the inflammatory process. To our knowledge the increase in IL-17A is a novel finding that may have new treatment implications.

Effect of Short-Term Low-Intensity Exercise Training on Association of Oxygen Free Radicals and Nitric Oxide Production in Patients with Acute Myocardial Infarction

Moderate-to-high intensity of exercise training within 2 to 3 months decreases oxygen free radicals (reactive oxygen species, ROS) and increases nitric oxide (NO) in outpatients with myocardial infarction. There is no data about the association of ROS and NO after short-term low-intensity exercise training within 5 days in patients hospitalized with acute myocardial infarction (AMI). A total of 32 male patients with AMI were randomized into two groups: 15 patients with short-term low-intensity exercise training within 5 days formed the training group and 17 patients without such exercise training formed the control group. All patients performed exercise treadmill test with modified Bruce protocol before and after the study. F2-isoprostane and NO concentration of the training group increased slightly after modified Bruce exercise treadmill test. Compared with the control group, NO of the training group was also slightly higher. Baseline NO and uric acid were negative predictor variables for F2-isoprostane in all patients hospitalized with AMI, and triglyceride was a positive predictor variable. After the study, physical capacity of the training group was higher; but heart rate and systolic blood pressure were lower significantly. This study showed that short-term low-intensity exercise training for patients hospitalized with AMI did not change ROS and NO productions, but it improved physical capacity and lowered heart rate and systolic blood pressure. NO was negative predictor variable for F2-isoprostane in controlling ROS changes in dynamic compensation mechanism.

Normobaric hypoxia conditioning reduces blood pressure and normalizes nitric oxide synthesis in patients with arterial hypertension

Insufficient production and/or increased decomposition of the potent endogenous vasodilator nitric oxide plays an important role in development and progression of arterial hypertension and its complications. One of the most effective means of stimulating endogenous nitric oxide synthesis is controlled adaptation to hypoxia. This study examined the effect of a 20-day, intermittent, normobaric intermittent hypoxia conditioning (IHC) program on blood pressure (BP) and nitric oxide production in patients with stage 1 arterial hypertension. The IHC sessions consisted of four to 10 cycles of alternating 3-min hypoxia (10% FIO2) and 3-min room air breathing. BP was monitored for 24 h before and after IHC, and nitric oxide synthesis was evaluated by 24-h urinary excretion of the stable nitric oxide metabolites nitrate and nitrite. IHC increased nitric oxide synthesis and decreased BP in hypertensive patients to values similar to those of normotensive individuals. Significant inverse correlations were found between nitric oxide production and disease duration, SBP, and DBP. Moreover, IHC enhancement of nitric oxide synthesis was especially robust in patients with arterial hypertension of more than 5 years duration. The reduction in BP persisted for at least 3 months in 28 of 33 hypertensive patients. IHC exerted a robust, persistent therapeutic effect and can be considered as an alternative, nonpharmacological treatment for patients with stage 1 arterial hypertension. The antihypertensive action of IHC is associated with normalization of nitric oxide production.

P11 Short-term effect of TNF-alpha blockade on nitric oxide production in patients with ankylosing spondylitis: correlation of serum nitrite level with clinical response and benefit

P11 Short-term effect of TNF-alpha blockade on nitric oxide production in patients with ankylosing spondylitis: correlation of serum nitrite level with clinical response and benefit

Impact of interval versus steady state exercise on nitric oxide production in patients with left ventricular dysfunction

Aim — The aim of the present study was to assess the impact of the interval exercise training (IET) vs. steady state exercise training (SSET) on nitric oxide production, through changes of circulating blood markers of endothelial function, including stable end-products of nitric oxide (NOx) and S-nitrosothiols (RSNOs) in patients with left ventricular dysfunction (LVD).Patients and methods — The impact of the IET vs. SSET on NOx and RSNOs production was assessed in a total of 31 (25 male, 6 female) patients with LVD (ejection fraction < 40%), who were admitted to our residential rehabilitation centre. Patients were randomised into an IET group (n = 18; 15 min interval exercise sessions, 2 times daily) and an SSET group (n = 13; 5-10 min steady state exercise sessions, 2 times daily), and exercised every day over a period of 3 weeks.The modified Saville-Griess method was used to determine NOx and RSNOs concentrations.Results — A significant increase was observed both for NOx (P < 0.05) and RSNOs (P < 0.001) in the IET group, as well as for RSNOs in the SSET group (P < 0.001). Both training methods were observed to significantly improve exercise capacity, as demonstrated for increased workload (P < 0.001 and P < 0.05 for the IET and SSET groups, respectively) and duration (P < 0.001 and P < 0.01 for the IET and SSET groups, respectively) of the exercise stress test at the end of the study.Conclusion — The results of the present study have demonstrated an increased nitric oxide production and improved exercise capacity in patients with left ventricular dysfunction, who were engaged in an interval exercise programme for three weeks, and clearly indicated an advantage of interval compared to steady state training method for cardiovascular rehabilitation.

Effect of intravenous albumin on endotoxin removal, cytokines, and nitric oxide production in patients with cirrhosis and spontaneous bacterial peritonitis

Objective. In patients with cirrhosis and spontaneous bacterial peritonitis (SBP), the use of intravenous albumin has been shown to prevent deterioration of renal function and to decrease the mortality rate, but the mechanisms remain unclear. The purpose of this study was to characterize the mechanisms of action of albumin with the focus on endotoxin and cytokines. Material and methods. Thirty patients with SBP were divided into two groups. Group 1 received antibiotics and albumin infusion (20% 50 cc every day for 3 days) and Group 2 received antibiotic treatment only. Twenty-four cirrhotic patients with sterile ascites were enrolled in Group 3 and received albumin infusion (20% 50 cc every day for 3 days). Plasma and ascitic fluid concentrations of endotoxin, nitric oxide products (NOx), tumor necrosis factor (TNF)-α, and interleukin (IL)-6 were analyzed before and after treatments, respectively. Results. Combination therapy of albumin and antibiotics can significantly (p<0.01) reduce plasma levels of TNF-α and IL-6, and ascitic fluid levels of endotoxin, TNF-α and IL-6 in cirrhotic patients with SBP. Without the addition of albumin to an antibiotic regimen, the plasma and ascitic fluid levels of NOx increased significantly in patients with SBP (p=0.005 and p=0.004, respectively). Conclusions. The results confirm that the beneficial effects of albumin are related to the reduction of the levels of TNF-α and NOx in both plasma and ascitic fluid. The infusion of albumin continuously for 3 days in addition to antibiotic treatment at the time of SBP detection is recommended as an effective therapy for patients with cirrhosis and SBP.

NITRIC OXIDE PRODUCTION AND PHAGOCYTOSIS IN PATIENTS WITH CHRONIC RECURRENT FURUNCULOSIS

In the article the results of evaluation of metabolic, nitric oxide productive functions and phagocytosis of leucocytes in patients with chronic recurrent furunculosis in the remission period of the disease are represented. The results of stimulated NBT-test in patients were significantly decreased. The increased level of nitric oxide production by mononuclear leucocytes of patients in comparison with healthy people was determined. In contrast to the control group the pirogenalum stimulation of patients’ leucocytes didn’t lead to increasing of nitric oxide production. The decreasing of functional reserve of reactive oxygen radicals and nitric oxide production in patients with chronic furunculosis in the remission period can be interpreted as the reflection of functional anergy of immune system.

No effect of short-term arginine supplementation on nitric oxide production, metabolism and performance in intermittent exercise in athletes

Arginine supplementation has been shown to alleviate endothelial dysfunction and improve exercise performance through increasing nitric oxide production in patients with cardiopulmonary diseases. In addition, arginine supplementation could decrease accumulations of lactate and ammonia, metabolites involved in development of muscular fatigue. The aim of this study was to investigate the effect of short-term arginine supplementation on performance in intermittent anaerobic exercise and the underlying mechanism in well-trained male athletes. Ten elite male college judo athletes participated with a randomized crossover, placebo-controlled design. The subjects consumed 6 g/day arginine (ARG trial) or placebo (CON trial) for 3 days then performed an intermittent anaerobic exercise test on a cycle ergometer. Blood samples were collected before supplementation, before and during exercise and 0, 3, 6, 10, 30 and 60 min after exercise. ARG trial had significantly higher arginine concentrations than CON trial at the same time point before, during and after exercise. In both trials, nitrate and nitrite concentration was significantly higher during and 6 min after exercise comparing to the basal concentration. The increase in nitrate and nitrite concentration during exercise in both trials was parallel to the increase in plasma citrulline concentrations. There was no significant difference between the 2 trials in plasma nitrate and nitrite, lactate and ammonia concentrations and peak and average power in the exercise. The results of this study suggested that short-term arginine supplementation had no effect on nitric oxide production, lactate and ammonia metabolism and performance in intermittent anaerobic exercise in well-trained male athletes.

Effect of growth hormone therapy on nitric oxide formation in cystic fibrosis patients

Airway nitric oxide production is decreased in cystic fibrosis. As growth hormone therapy has been shown to increase nitric oxide production in growth hormone-deficient patients, it may also affect nitric oxide production in patients with cystic fibrosis. The objective of the present study was to investigate the effect of growth hormone therapy on systemic and airway nitric oxide formation in patients with cystic fibrosis. Nitric oxide metabolites in serum and urine, amino acid concentrations in serum and sputum, as well as exhaled nitric oxide, were measured in children with cystic fibrosis before, during and after 1 yr of treatment with human growth hormone. Nitric oxide metabolite concentrations increased significantly in serum and urine during the treatment period. Serum amino acid concentrations (including l-arginine, the substrate for nitric oxide synthases) also increased during treatment. The systemic bioavailability of l-arginine for nitric oxide synthases, expressed as ratio of l-arginine/l-ornithine+lysine, remained unchanged. In contrast, l-arginine concentrations in sputum decreased significantly during growth hormone treatment, as did exhaled nitric oxide levels. Treatment with growth hormone in children with cystic fibrosis decreases exhaled nitric oxide by reducing the concentration of l-arginine in the airways.

Continuous Positive Airway Pressure Improves Daytime Baroreflex Sensitivity and Nitric Oxide Production in Patients with Moderate to Severe Obstructive Sleep Apnea Syndrome

Individuals with obstructive sleep apnea syndrome (OSAS) are at high risk for cardiovascular morbidity and mortality. The effects of OSAS severity and nocturnal continuous positive airway pressure (CPAP) on daytime baroreflex sensitivity (BRS) and nitric oxide (NO) production were investigated in OSAS patients. Fifty-one consecutive males with OSAS and 29 age-matched healthy men underwent the Valsalva test and standard polysomnography. Patients with an apnea-hypopnea index (AHI) of >or=20 episodes per hour were randomized to receive CPAP treatment for 3 months (n=14) or no such treatment (n=19). The BRS index measured from the overshoot phase (phase IV) of the Valsalva maneuver and plasma NO concentration were significantly lower, whereas the AHI, oxygen desaturation time, arousal index, percentage of sleep stage 1, and systolic blood pressure were significantly greater, in patients with an AHI of >or=20/h than in those with an AHI of <20/h or in controls. The 24-h urinary excretion of norepinephrine was significantly reduced and the plasma NO concentration was significantly increased after one night of CPAP. The BRS index for phase IV and the Valsalva ratio were significantly increased in the CPAP group after the 3-month treatment period but remained unchanged in the non-CPAP group of OSAS patients. The daytime BRS index and NO production were thus inversely related to the severity of OSAS, and successful CPAP treatment improved these parameters in patients with moderate to severe OSAS. CPAP may therefore reduce the risk of cardiovascular complications due to endothelial dysfunction or increased sympathetic activity.

Biventricular versus right ventricular pacing decreases immune activation and augments nitric oxide production in patients with chronic heart failure

Immune system activation and oxidative stress are involved in the pathogenesis of heart failure (HF). We aimed to test the hypothesis that upgrading from right ventricular pacing (RVp) to biventricular pacing (BiVp) can counteract these phenomena. 28 HF patients, with BiVp were switched to RVp for one week, and then returned to BiVp. Immediately prior to, and 48 h after the return to BiVp, left ventricular (LV) systolic function was evaluated by echocardiography, and serum N-terminal pro-brain natriuretic peptide (NTproBNP), C-reactive protein (CRP), tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL6), nitric oxide metabolites (NO(x)) and malondialdehyde (MDA) were assayed. LV systolic function significantly improved 48 h after switching from RVp to BiVp: Ao-VTI (p<0.001), SV (p<0.001) and CO (p<0.001), and mitral regurgitation significantly decreased (p=0.003). At the same time, indices of peripheral immune activation decreased: TNF-alpha (p=0.02) and IL6 (p<0.001). MDA decreased (p<0.001), whereas NO(x) increased (p=0.04). NTproBNP and CRP did not change. In addition, in "responders" (i.e. CO increase >10% during BiVp vs. RVp) NTproBNP decreased and NO(x) increased. However, during BiVp, the decreases in TNF-alpha, IL6, and MDA occurred both in responders and in non-responders and were accompanied by a reduction in mitral regurgitation. The beneficial effect of BiVp compared to RVp extends beyond improving cardiac haemodynamics and comprises a decrease in immune activation accompanied by an increase in serum NO(x) and decrease in serum MDA.

Circadian changes in nitric oxide production in patients with arterial hypertension

Circadian changes in nitric oxide production in patients with arterial hypertension

Decreased Whole Body Endogenous Nitric Oxide Production in Patients with Primary Pulmonary Hypertension

Impaired pulmonary release of nitric oxide (NO) is one of the characteristic phenotypic changes of vascular cells in pulmonary hypertension. The aim of this study was to determine nitric oxide synthase (NOS)-dependent whole body NO production in patients with primary pulmonary hypertension. NOS-dependent whole body NO production was assessed by giving an intravenous infusion of L-[¹⁵N]₂-arginine (50 µmol/min for 30 min) and measuring isotopic urinary enrichment of ¹⁵N-nitrite and ¹⁵N-nitrate. Four female patients with no signs of infection were recruited and compared with 6 age-matched control subjects. Mean 12-hour excretion of ¹⁵N-nitrite and ¹⁵N-nitrate in the total urine over 36 h was smaller in patients than in control subjects (57.2 ± 27.6 vs. 229.1 ± 65.2 nmol/mmol creatinine, p< 0.01, Mann-Whitney U test, respectively). Neither mean 12-hour excretion of ¹⁴N-nitrite and ¹⁴N-nitrate (51.6 ± 10.0 vs. 72.4 ± 10.0 µmol/mmol creatinine, p = 0.3) nor glomerular filtration rates (84.5 ± 15.8 vs. 129.7 ± 16.0 ml/min, p = 0.1) were different between patients and control subjects. Our results suggest that either basal NOS-dependent whole body NO production is impaired or excess NO metabolism occurs in patients with primary pulmonary hypertension.

Leflunomide reduces nitric oxide production in patients with active rheumatoid arthritis

Objectives Leflunomide is an immunomodulatory agent that was recently approved for the treatment of rheumatoid arthritis (RA). The mechanism of action is not fully understood. Nitric oxide (NO) plays an important role in the pathogenesis of RA. Leflunomide has been shown to cause cell specific inhibition of inducible nitric oxide synthase (iNOS) activation in animal models. We carried out this study to determine if there was alteration in NO production in patients with RA. Methods An 8-week open label study was carried out on patients with adult onset active RA. We measured levels of nitrite and citrulline spectrophotometrically as surrogate markers of NO production. Within-patient serum levels of nitrite and citrulline were compared with leflunomide therapy at three points of time (at 0, 4 and 8 weeks of therapy). Results Thirty-three patients with active RA were enrolled for this study. These patients were a subset of 63 individuals who are studied for clinical efficacy of leflunomide. Three patients were lost to follow-up. Median nitrite levels were 817.2 (nmol/ml) at the start of therapy and this declined to 440.9 nmol/ml and 301.1 nmol/ml at 4 and 8 weeks of therapy. Median citrulline levels were 649.3 nmol/ml at the start of the study, which declined to 549.2 nmol/ml and 485.4 nmol/ml at 4 and 8 weeks, respectively. Statistically significant decrease in median values for serum nitrite and citrulline levels was documented after 4 weeks of leflunomide therapy ( p<0.01), which was sustained at 8 weeks ( p<0.01), although there was no further fall between 4 and 8 weeks ( p>0.1). Conclusions Leflunomide inhibits nitric oxide production in patients with active RA. Inhibition of NO synthesis may be one of the mechanisms responsible for the immunomodulatory activity of leflunomide.