Total nitrite/nitrate in expired breath condensate of patients with asthma

Abstract

Production of nitric oxide (NO) is generally increased during inflammatory diseases including asthma. The eventual fate of NO is oxidation to nitrite (NO2) and nitrate (NO3), both of which are end-products of NO metabolism. Hydrogen Peroxide (H2O2) is increased in exhaled breath condensate of asthmatic subjects and may be used as a non-invasive marker of oxidative stress. NO has in some cases been shown to attenuate oxidant-induced lung injury. Total NO2/NO3 concentration and H2O2 levels were measured in expired breath condensate in 50 clinically stable asthmatics [all males, all atopics, mean age 22 (3) SD yrs, forced expiratory volume in 1 sec (FEV1) 91 (10)% predicted, PD20 to histamine 0.262 (0.16) mg 20 on inhaled steroids, 20 smokers, all steroid-naive] and in 10 normal, non-atopic subjects [all males, age 23 (4) yrs, FEV1 101 (14)% predicted, PD20 to histamine 1.3 (0.55) mg]. NO2/NO3 levels were significantly higher in patients with asthma than in normal subjects (1.08, 95% CI 0.86-1.3 microM vs. 0.6; 95% CI 0.46-0.8, P < 0.001). Patients who were on inhaled steroids had significantly ower values compared to steroid-naive (0.71, 95% CI 0.55-0.87 microM vs. 133, 95% CI 1-1.65 microM, P < 0.001). Similar results were observed between smokers and non-smokers (1.11, 95% CI 0.74-1.47 microM vs. 1.77, 95% CI 1.1-24 microM, P < 0.0001). There was a significant positive correlation between NO2/NO3 levels and H2O2 concentration in expired breath condensate (r = 0.48, P < 0.0001). No correlation was observed between NO2/NO3 levels, airway obstruction and bronchial hyper-reactivity as assessed by PD20 to histamine. Total NO2/NO3 levels in expired breath condensate are raised in patients with stable asthma and are significantly related to oxidative stress as assessed by H2O2 concentration. Measurement of expired breath NO2/NO3 and H2O2 levels may be clinically useful in the management of oxidation and inflammation mediated lung injury.

Exhaled breath condensate: methodological recommendations and unresolved questions

“…1). These collecting vessels are cooled with wet ice [5], air [24] metal [25] or dry ice to the required temperature. Comparing a custom-made device (Tygon tubing immersed in thawing ice) with a commercially available condenser (Teflon coated laminated metal tube cooled to -20˚C) one study showed that the use of the two devices are interchangeable when measuring MDA, hexanal, heptanal or nonanal [21].…”

“…Protocols, recommendations and potential pitfalls NO 2 -and NO 3 -have been detected in EBC by using spectrophotometric assays (Griess reaction), a fluorimetric method (2,3-diaminonapthalene (DAN) reaction), chemiluminescence assays or ion chromatography followed by conductivity measurement [91][92][93][94][95][96][97][98][99][100][101][102][103][104]. The reported detection limit of the DAN assay is 0.1 mM and that of the Griess reaction is higher [91,92].…”

Prostaglandin E2in the expired breath condensate of patients with asthma

“…The collection of EBC was performed as previously described [15]. Briefly, a heat exchanger unit (RHES, model 6V3; Jaeger, Wuerzburg, Germany) was used to produce cold air of -15uC--18uC at an airflow of w80 L?min -1 .…”

“…after 2 days, 1 week, 2 weeks and 3 weeks of storage (the maximum time between collection and measurement in the frozen samples). All condensate samples were tested for salivary contamination by determination of amylase activity, as previously described [15].…”

Toward point-of-care management of chronic respiratory conditions: Electrochemical sensing of nitrite content in exhaled breath condensate using reduced graphene oxide

“…Nitrite is typically detected through one of several spectrophotometric methods (Griess reaction) involving fluorimetry, chemiluminescence, or ion chromatography [15][16][17][18][19][20][21][22][23][24][25][26][27][28] . The detection limit of fluorimetric methods is 0.1 μM.…”