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NOx Concentrations (nox + concentration)
Selected AbstractsNeurohormonal and Circulatory Effects of Short-Term Treatment with Enalapril and Quinapril in Dogs with Asymptomatic Mitral RegurgitationJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 5 2005Sophia Gry Moesgaard The aim of the study was to compare the effect of 2 angiotensin-converting enzyme (ACE) inhibitors on neurohormonal and circulatory variables in Cavalier King Charles Spaniels (CKCSs) with asymptomatic mitral regurgitation (MR). Ten CKCSs with mild to severe untreated MR were treated with 2 ACE inhibitors, quinapril and enalapril (each at 0.5 mg/kg PO q24h for 7 days), in a double-blind, crossover study with a washout period of 7 days between treatments. Blood samples were drawn and echocardiography was performed on days 0, 7, 14, and 21. Both treatments reduced ACE activity (P < .001) and increased renin activity (P < .001) and atrial natriuretic peptide concentration (P < .005). The ACE inhibitors had no effect on the concentrations of nitrate and nitrite (NOx) or asymmetric dimethylarginine (ADMA). On day 0, a lower NOx concentration (P= .02) was found in samples taken in the clinic as compared to samples taken in the homes of the dogs. Quinapril caused a significant reduction in more variables that reflect the severity of MR (eg, jet size and left ventricular end diastolic diameter) than did enalapril. However, in terms of specific variables, no significant difference was identified between the effects of the 2 treatments on MR. These results suggest that ACE inhibitors do not affect NOx and ADMA concentrations in asymptomatic dogs, but exercise, stress, or some combination may influence NOx concentrations in these dogs. [source] Decreased Plasma Concentration of Nitric Oxide Metabolites in Dogs with Untreated Mitral RegurgitationJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 2 2003Henrik D. Pedersen Endothelium-dependent (nitric oxide [NO]-mediated) vasodilation is impaired in humans with heart failure. This dysfunction is an important therapeutic target. The plasma concentration of the NO metabolites nitrate and nitrite (collectively referred to as NOx) is a measure of whole-body NO production, provided that the dietary intake of the ions is low. Fifty clinically healthy dogs older than 1 year (median 5.0 years; interquartile interval 2.6,8.2 years) were studied, including 9 controls of various breeds, 23 Cavalier King Charles Spaniels (CKCSs) with no or minimal mitral regurgitation (MR), 9 CKCSs with mild MR (regurgitant jet occupying 15,50% of the left atrial area), and 9 CKCS with moderate to severe MR (jet ± 50%) due to myxomatous valve disease. None of the dogs received medication. The dogs were given NOx-free water and a diet with a low concentration of NOx for 96 hours before blood sampling. Multiple linear regression analysis revealed that dog group, but not gender, age, serum creatinine concentration, and platelet count, was associated with NOx concentrations. Control dogs had the same NOx concentration (median 20.0 ,M; interquartile interval 15.1,25.5 ,M) as CKCSs without MR (median 18.7 ,M; interquartile interval 15.5,25.9 ,M). Compared to CKCSs without MR, the NOx concentration was lower in CKCSs with mild (median 12.9 ,M; interquartile interval 11.0,13.5 ,M; P= .04) and moderate to severe (median 11.2 ,M; interquartile interval 6.9,17.1 ,M; P= .02) MR. In conclusion, CKCSs with mild to severe, clinically silent MR have decreased plasma NOx concentrations, suggesting that endothelial dysfunction develops early in the course of developing MR in dogs. [source] Helicobacter pylori Infection Increases Serum Nitrate and Nitrite More Prominently Than Serum PepsinogensHELICOBACTER, Issue 1 2002Kanji Kodama Abstract Background.Helicobacter pylori infection causes chronic gastritis and results in increased serum concentrations of pepsinogens I and II as well as gastrin, while the ratio of pepsinogen I to II (I : II) is decreased. Inducible nitric oxide synthase (iNOS) is induced in H. pylori -associated gastritis and may modulate inflammation. However serum nitrate and nitrite (NOx) concentrations in patients with H. pylori -induced chronic gastritis have not been reported. We examined differences in serum NOx between H. pylori -negative and positive volunteers relative to differences in pepsinogens and gastrin. Materials and methods. Sera from 80 healthy asymptomatic volunteers younger than 36 years were analyzed for anti- H. pylori antibody, NOx, gastrin and pepsinogens. Results. In H. pylori antibody-positive subjects serum NOx concentrations were higher than in negative subjects (p < .005). In H. pylori -negative subjects, NOx correlated with pepsinogen II (r = .405, p < .05). In subjects with low pepsinogen I or II, NOx was higher in H. pylori -positive than negative subjects (p < .001). In subjects with high pepsinogen I : II (6 or higher), serum NOx was higher in H. pylori -positive than in negative subjects. Conclusions.H. pylori -induced gastritis increases serum NOx concentrations more prominently than those of pepsinogen. In H. pylori -negative subjects, serum correlates with serum pepsinogen II. [source] Plasma Asymmetric Dimethylarginine, Symmetric Dimethylarginine, l -Arginine, and Nitrite/Nitrate Concentrations in Cats with Chronic Kidney Disease and HypertensionJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 2 2008R.E. Jepson Background: Chronic kidney disease (CKD) and hypertension have been associated with decreased bioavailability of nitric oxide (NO) and endothelial dysfunction. Increased concentrations of the endothelial nitric oxide synthase (eNOS) inhibitor asymmetric dimethylarginine (ADMA) are implicated. Hypothesis: Plasma ADMA concentration is increased in cats with CKD and systemic hypertension corresponding to a decrease in total plasma nitrate/nitrite (NOx) availability. Decrease in systolic blood pressure (SBP) and proteinuria during treatment of hypertension with amlodipine besylate may be associated with increased NOx availability. Animals: Sixty-nine client-owned normotensive and hypertensive cats with variable azotemia. Methods: Plasma ADMA, symmetric dimethylarginine (SDMA), and l -arginine were measured simultaneously by hydrophilic-interaction liquid chromatography-electrospray tandem mass spectrometry in cats from 6 groups: normotensive nonazotemic (n = 10), normotensive mildly azotemic (n = 10), hypertensive mildly azotemic with hypertensive retinopathy (n = 20), hypertensive mildly azotemic without hypertensive retinopathy (n = 10), normotensive moderately azotemic cats (n = 10), and hypertensive nonazotemic cats (n = 9). Plasma NOx concentrations were measured. Results: A moderate correlation between plasma creatinine and ADMA (n = 69, r= .608, P < .001), SDMA (n = 69, r= .741, P < .001), and NOx concentrations (n = 69, r= .589, P < .001) was observed. There was no association among plasma ADMA, SDMA, and NOx concentrations and SBP. Conclusions and Clinical Importance: Plasma ADMA and SDMA concentrations are increased in cats with CKD and correlate with plasma creatinine concentration. This may imply the presence of endothelial dysfunction in cats with CKD. Plasma ADMA concentrations were not associated with systemic hypertension. Treatment of systemic hypertension with amlodipine besylate did not affect plasma ADMA or NOx concentrations. [source] Neurohormonal and Circulatory Effects of Short-Term Treatment with Enalapril and Quinapril in Dogs with Asymptomatic Mitral RegurgitationJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 5 2005Sophia Gry Moesgaard The aim of the study was to compare the effect of 2 angiotensin-converting enzyme (ACE) inhibitors on neurohormonal and circulatory variables in Cavalier King Charles Spaniels (CKCSs) with asymptomatic mitral regurgitation (MR). Ten CKCSs with mild to severe untreated MR were treated with 2 ACE inhibitors, quinapril and enalapril (each at 0.5 mg/kg PO q24h for 7 days), in a double-blind, crossover study with a washout period of 7 days between treatments. Blood samples were drawn and echocardiography was performed on days 0, 7, 14, and 21. Both treatments reduced ACE activity (P < .001) and increased renin activity (P < .001) and atrial natriuretic peptide concentration (P < .005). The ACE inhibitors had no effect on the concentrations of nitrate and nitrite (NOx) or asymmetric dimethylarginine (ADMA). On day 0, a lower NOx concentration (P= .02) was found in samples taken in the clinic as compared to samples taken in the homes of the dogs. Quinapril caused a significant reduction in more variables that reflect the severity of MR (eg, jet size and left ventricular end diastolic diameter) than did enalapril. However, in terms of specific variables, no significant difference was identified between the effects of the 2 treatments on MR. These results suggest that ACE inhibitors do not affect NOx and ADMA concentrations in asymptomatic dogs, but exercise, stress, or some combination may influence NOx concentrations in these dogs. [source] Decreased Plasma Concentration of Nitric Oxide Metabolites in Dogs with Untreated Mitral RegurgitationJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 2 2003Henrik D. Pedersen Endothelium-dependent (nitric oxide [NO]-mediated) vasodilation is impaired in humans with heart failure. This dysfunction is an important therapeutic target. The plasma concentration of the NO metabolites nitrate and nitrite (collectively referred to as NOx) is a measure of whole-body NO production, provided that the dietary intake of the ions is low. Fifty clinically healthy dogs older than 1 year (median 5.0 years; interquartile interval 2.6,8.2 years) were studied, including 9 controls of various breeds, 23 Cavalier King Charles Spaniels (CKCSs) with no or minimal mitral regurgitation (MR), 9 CKCSs with mild MR (regurgitant jet occupying 15,50% of the left atrial area), and 9 CKCS with moderate to severe MR (jet ± 50%) due to myxomatous valve disease. None of the dogs received medication. The dogs were given NOx-free water and a diet with a low concentration of NOx for 96 hours before blood sampling. Multiple linear regression analysis revealed that dog group, but not gender, age, serum creatinine concentration, and platelet count, was associated with NOx concentrations. Control dogs had the same NOx concentration (median 20.0 ,M; interquartile interval 15.1,25.5 ,M) as CKCSs without MR (median 18.7 ,M; interquartile interval 15.5,25.9 ,M). Compared to CKCSs without MR, the NOx concentration was lower in CKCSs with mild (median 12.9 ,M; interquartile interval 11.0,13.5 ,M; P= .04) and moderate to severe (median 11.2 ,M; interquartile interval 6.9,17.1 ,M; P= .02) MR. In conclusion, CKCSs with mild to severe, clinically silent MR have decreased plasma NOx concentrations, suggesting that endothelial dysfunction develops early in the course of developing MR in dogs. [source] Spontaneous labor increases nitric oxide synthesis during the early neonatal periodPEDIATRICS INTERNATIONAL, Issue 4 2001Akihiko Endo AbstractBackground: This paper aimed to assess the influence of spontaneous labor upon endogenous nitric oxide (NO) and endothelin 1 (ET-1) during transition to extrauterine life. Methods: The serum levels of NO metabolites (the sum of nitrites and nitrates (NOx)) and the plasma level of ET-1 were determined in 53 healthy full-term infants (spontaneous labor group; n=40, cesarean delivery group; n=13). In both groups, blood samples were obtained from a cord vein at birth and from a peripheral vein at 5 days of age. Results: The differences in serum NOx concentrations between the spontaneous labor group and the elective cesarean group were not significant at birth. By the age of 5 days, serum NOx concentrations had risen significantly in the spontaneous labor group to become significantly higher in the elective cesarean group. Conclusion: It is speculated that spontaneous labor might enhance endogenous NO synthesis at 5 days of age. [source] NG -NITRO- l -ARGININE METHYL ESTER POTENTIATES ANAPHYLACTIC VENOCONSTRICTION IN RAT PERFUSED LIVERSCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 11 2006Toshishige Shibamoto SUMMARY 1The effects of the nitric oxide (NO) synthase inhibitor NG -nitro- l -arginine methyl ester (l -NAME) on anaphylaxis-induced venoconstriction were examined in rat isolated livers perfused with blood-free solutions in order to clarify the role of NO in anaphylactic venoconstriction. 2Rats were sensitized with ovalbumin (1 mg) and, 2 weeks later, livers were excised and perfused portally in a recirculating manner at a constant flow with Krebs',Henseleit solution. The antigen (ovalbumin; 0.1 mg) was injected into the reservoir 10 min after pretreatment with l-NAME (100 mmol/L) or d -NAME (100 mmol/L) and changes in portal vein pressure (Ppv), hepatic vein pressure (Phv) and perfusate flow were monitored. In addition, concentrations of the stable metabolites of NO ( and ) were determined in the perfusate using an HPLC,Griess system. 3The antigen caused hepatic venoconstriction, as evidenced by an increase in Ppv from a mean (SEM) baseline value of 7.7 ± 0.1 cmH2O to a peak of 21.4 ± 1.1 cmH2O at 3 min in d -NAME-pretreated livers. Pretreatment with l-NAME augmented anaphylactic venoconstriction, as reflected by a higher Ppv (27.4 ± 0.8 cmH2O) after antigen than observed following d -NAME pretreatment. The addition of l -arginine, a precursor for the synthesis of NO, reversed the augmentation of anaphylactic venoconstricion by l -NAME. This suggests that hepatic anaphylaxis increased the production of NO, which consequently attenuated anaphylactic venoconstriction. However, perfusate NOx levels did not increase significantly after antigen in livers pretreated with either l -NAME or d -NAME. 4In conclusion, l -NAME potentiates rat anaphylactic hepatic venoconstriction, suggesting that NO contributes to the attenuation of the venoconstriction. However, this functional evidence was not accompanied by corresponding changes in perfusate NOx concentrations. [source] ORIGINAL ARTICLE: Characteristics of plasma NOx levels in severe sepsis: high interindividual variability and correlation with illness severity, but lack of correlation with cortisol levelsCLINICAL ENDOCRINOLOGY, Issue 3 2010J. T. Ho Summary Objectives, Nitric oxide (NO) concentrations are elevated in sepsis and their vasodilatory action may contribute to the development of hyperdynamic circulatory failure. Hydrocortisone infusion has been reported to reduce nitric oxide metabolite (NOx) concentrations and facilitate vasopressor withdrawal in septic shock. Our aim was to determine whether NOx concentrations relate to (i) protocol-driven vasopressor initiation and withdrawal and (ii) plasma cortisol concentrations, from endogenous and exogenous sources. Demonstration of a relation between NOx, cortisol and vasopressor requirement may provide an impetus towards the study of hydrocortisone-mediated NOx suppression as a tool in sepsis management. Design, A prospective study of 62 patients with severe sepsis admitted to the intensive care unit. Measurements, Plasma NOx, total and free cortisol, and corticosteroid-binding globulin (CBG) concentrations were measured and related to protocol-driven vasopressor use for 7 days following admission. Results, Patients who developed septic shock (n = 35) had higher plasma NOx, total and free cortisol, and lower CBG concentrations than the nonseptic shock group (n = 27). Cortisol, CBG and NOx concentrations correlated with illness severity. Free cortisol, and to a lesser extent total cortisol, but not NOx concentrations, predicted septic shock. NOx concentrations were higher in nonsurvivors, and the concentrations were characteristically stable within individuals but marked interindividual differences were only partly accounted for by illness severity or renal dysfunction. NOx concentrations did not correlate with cortisol, did not relate to vasopressor requirement and did not fall after standard dose hydrocortisone, given for clinical indications. Conclusions, Nitric oxide production increased with sepsis severity but did not correlate with plasma cortisol or vasopressor requirement. NOx levels were not suppressed reproducibly by hydrocortisone. High interindividual variability of NOx levels suggests that absolute NOx levels may not be a suitable target for individualized hydrocortisone therapy. [source] Plasma nitrite/nitrate and endothelin-1 concentrations in neonatal sepsisACTA PAEDIATRICA, Issue 5 2003J Figueras-Aloy Aim: To determine the changes in plasma nitrite/nitrate (NOx) and endothelin-1 (ET-1) concentrations during neonatal sepsis. Methods: In a prospective study, 60 consecutive newborns meeting the criteria for sepsis and without receiving exogenous nitric oxide (25 haemoculture-positive [HC+] and 35 haemoculture-negative [HC,]) were compared with 68 healthy newborns (46 full-term and 22 preterm). NOx and ET-1 concentrations were measured in each newborn within 48 h of diagnosis of sepsis and then every third day up to three determinations. SNAP-II and SNAPPE-II severity scores were performed at the moment of highest clinical severity. Results: At the beginning of the sepsis period, controls and septicaemic newborns had similar NOx and ET-1 levels, with the exception of infants with severe HC+ sepsis. Throughout the sepsis period, NOx increased in moderate HC+ sepsis and decreased in HC, sepsis, reaching a significant difference at the end of the study period (59.9 ± 72.7 vs 33.9 ± 15.3 ,mol/L; p= 0.036). Meanwhile, ET-1 in newborns with severe HC+ sepsis remained higher than that in the moderate HC+ sepsis group and HC, group, reaching significant differences in all the periods. The highest ET-1 value was positively correlated with SNAP-II and SNAPPE-II scores. Conclusion: NOx concentrations increased throughout the neonatal HC+ sepsis period, reaching significant differences after 7,9 d. The highest ET-1 levels in neonatal HC+ sepsis emerged before the NOx peak, at 3,5 d, and later decreased. Only newborns with severe HC+ sepsis presented a significant increase in ET-1 concentrations from the beginning of the septicaemic process. [source] | ||||||||||