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Background: Cigarette smoking is associated with decreased nitric oxide (NO) production and increased oxidative stress in the airways. Exhaled NO levels are not higher in asthmatic smokers than in healthy non-smokers, and the value of exhaled NO for diagnosing asthma in smokers has been questioned., Objectives: To compare exhaled NO concentrations between healthy and steroid-naive and steroid-treated asthmatic smokers and non-smokers. To also assess the acute effect of cigarette smoking on exhaled NO and hydrogen peroxide (H(2)O(2)) levels in asthmatic smokers., Methods: Exhaled NO was measured by chemiluminescence and exhaled H(2)O(2) spectrophotometrically. In 7 steroid-naive asthmatic smokers exhaled NO and H(2)O(2) was measured both before and 15 min after smoking one cigarette. Data are given as median (range)., Results: Exhaled NO level was significantly higher in steroid-naive asthmatic smokers than in healthy smokers [7.7 (3.4-32.5) ppb vs. 3.2 (2.0-7.2) ppb, p < 0.001]. Exhaled NO values were lower in smokers than in non-smokers both in healthy subjects and in steroid-naive asthmatic patients. Steroid-treated asthmatic smokers had a tendency for lower exhaled NO values [5.4 (1.7-12.0) ppb] compared to steroid-naive asthmatic smokers. Cigarette smoking caused an acute increase in exhaled H(2)O(2) concentrations together with a decrease in exhaled NO concentration., Conclusions: Our data suggest that an elevation in exhaled NO concentration is associated with asthma in smokers. This difference may be useful for diagnosing the disease in smokers, but its clinical value needs further evaluation. Acute increase in exhaled H(2)O(2) concentrations suggests that smoking increases the oxidative stress in the asthmatic airways.

Hyperresponsiveness (AHR) is a key physiological abnormality in asthma. In clinical and research studies AHR is measured bronchial challenge, with methacholine (MCh), but more recently with adenosine-5'-monophosphate (AMP). In the search for markers of airway inflammation in asthmatic patients, we measured the concentrations of histamine and cysteinyl-leukotrienes (cys-LTs) before and after MCh and AMP challenges in the exhaled breath condensate of 13 patients with mild asthma (FEV1 78.5%pred) and nine healthy non-smokers, using specific enzyme immunoassays. With methacholine challenge we did not find any differences between asthmatics and normal subjects in the pre- and post-challenge concentrations of cys-LTs: 27.2+/-1.4 vs. 29.2+/-1.2 pg/ml and 26.3+/-2.2 vs. 27.5+/-4.2 pg/ml, respectively or histamine: 5.1+/-0.4 vs. 5.1+/-0.6 nM and 4.5+/-0.4 vs. 4.4+/-0.3 nM; P>0.05). In asthmatic patients cys-LT levels were significantly higher after AMP challenge (56.2+/-9.7 vs. 31.7+/-6.9 pg/ml; P<0.05); but there was no difference in healthy subjects (27.2+/-4.6 vs. 30.3+/-4.7 pg/ml). There was no difference in histamine concentrations in asthmatic (5.9+/-1.8 vs. 4.5+/-0.5 nM), or healthy subjects (5.5+/-0.4 vs.5.7+/-0.9 nM) after AMP challenge. In conclusion, our results show that the cys-LTs are increased in exhaled breath condensate after AMP challenge, which may indicate that the AMP acts indirectly by releasing cys-LTs from primed mast cells. The detection of LTs and histamine in exhaled breath condensate may be useful in monitoring asthma.

Exhaled breath condensate (EBC) has been proposed as a noninvasive tool to study airway inflammation. The reproducibility of breath condensates was recently questioned. We therefore measured sodium and chloride concentrations in EBC and assessed the repeatability of these measurements in healthy adults and children with airway disease. We investigated technical repeatability and within-day repeatability in five healthy adults, and compared these results with those of 10 asthmatic children and 9 children with cystic fibrosis (CF). We also assessed within-period repeatability in the healthy controls. We report that the variability of measurements was similar for within sample, within day, and between visits, for both normals and children with asthma and CF, and that the major source of variability of sodium and chloride measurements is restricted by the reproducibility of the measurement assay method used. The wide use of EBC is more likely to depend on the development of highly sensitive and reproducible assays, rather than further refinements of the collection technique., (Copyright 2004 Wiley-Liss, Inc.)

Exhaled breath analysis may be used to quantify inflammation and oxidative stress in the respiratory tract, in the differential diagnosis of airway diseases, and in the monitoring of therapy. The greatest progress has been made with standardized measurement of exhaled nitric oxide (NO). Bronchial NO is increased in asthma, correlated with other markers of inflammation, and reduced by treatment with corticosteroids and antileukotrienes. Alveolar NO is increased in chronic obstructive pulmonary disease (COPD), reflecting disease severity and progression. Exhaled carbon monoxide and ethane are increased in both asthma and COPD. Increased concentrations of 8-isoprostane, hydrogen peroxide, nitrite, and nitrotyrosine are found in exhaled breath condensate from patients with inflammatory lung diseases. Increased levels of lipid mediators are also found, and the pattern depends on the nature of the disease process. Additional biomarkers are exhaled breath temperature, which is elevated in asthma and reduced in COPD, and bronchial blood flow. It is likely that smaller and more sensitive analyzers will extend the discriminatory value of exhaled breath analysis and that new techniques will become available to diagnose and monitor respiratory diseases in the family practice and home settings.

Background: Chronic obstructive pulmonary disease (COPD) is characterised by chronic inflammation of the respiratory tract., Methods: We investigated the presence of interleukin-6 (IL-6: a cytokine secreted by monocytes/macrophages, T cells, B cells, fibroblasts, bone marrow stromal cells, keratinocytes and endothelial cells) in the exhaled breath condensate of 16 exsmokers with moderate COPD, 12 healthy non-smokers. IL-6 was measured by means of a specific enzyme immunoassay., Results: IL-6 levels were detectable in all of the subjects, but were higher in the COPD patients (8.0 +/- 0.1 pg/ml; P < 0.0001) than in the healthy non-smokers (4.9 +/- 0.2 pg/ml) with a correlation in this group between age and IL-6 levels (r = 0.597; P < 0.05)., Conclusions: The increased IL-6 levels in exhaled breath condensate may reflect airway inflammation in patients with COPD.

Study Objectives: Obstructive sleep apnea (OSA) is characterized by recurrent apnea during sleep that may compromise oxidative balance. Oxidative stress is increased in the blood and in the airways of OSA patients., Design: The aim of this study was to investigate whether oxidative stress is determined by nocturnal apneas and could be reduced by CPAP therapy, and whether there is a relation between local and systemic oxidative stress in these patients., Patients and Methods: Eighteen patients with OSA (13 men; mean [+/- SD] age, 48 +/- 3 years) and 12 healthy age-matched and weight-matched subjects (8 men; mean age, 46 +/- 7 years) were recruited. 8-Isoprostane was measured in exhaled breath condensate and blood by a specific enzyme immunoassay., Measurements and Results: Higher concentrations of 8-isoprostane were found in the morning exhaled condensate (9.5 +/- 1.9 pg/mL) and plasma (9.7 +/- 1.5 pg/mL) of OSA patients compared to healthy obese subjects (6.7 +/- 0.2 and 7.1 +/- 0.3 pg/mL, respectively; p < 0.0001). Elevated mean concentrations of exhaled 8-isoprostane were observed in the OSA patients at 8:00 AM (9.5 +/- 1.9 pg/mL) but not at 8:00 PM (7.6 +/- 0.8 pg/mL; p < 0.0005), and a significant reduction was seen after continuous positive airway pressure (CPAP) therapy (7.7 +/- 0.9 pg/mL; before treatment, 9.6 +/- 1.7 pg/mL; p < 0.005). A positive correlation was found between morning exhaled 8-isoprostane levels and the apnea-hypopnea index (r = 0.8; p < 0.0001), and 8-isoprostane levels and neck circumference (r = 0.6; p < 0.0001)., Conclusions: These findings suggest that systemic and local oxidative stress are increased in OSA patients, and that they are higher after nocturnal apnea and reduced by CPAP therapy.

The inducible isoenzyme of nitric oxide synthase (iNOS) generates nitric oxide (NO) in inflammatory diseases such as asthma. The prodrug L-N6-(1-iminoethyl)lysine 5-tetrazole amide (SC-51) is rapidly converted in vivo to the active metabolite L-N6-(1-iminoethyl)lysine (L-NIL). Initially, we performed in vitro experiments in human primary airway epithelial cells to demonstrate that L-NIL causes inhibition of iNOS. In a randomized double-blind placebo-controlled crossover trial, SC-51 was administered as a single oral dose (20 or 200 mg) in separate cohorts of healthy volunteers (two groups of n=12) and mild asthmatic patients (two groups of n=12). SC-51 (200 mg) reduced exhaled breath NO levels to <2 ppb in both healthy volunteers (P<0.001) and mild asthmatics (P<0.001) within 15 min, representing >90% inhibition of baseline levels of NO in asthmatic patients, with the effects lasting at least 72 h. There were no significant effects on blood pressure, pulse rate, or respiratory function (FEV1). This study demonstrates that an inhibitor of iNOS produces marked inhibition of exhaled breath NO in normal and asthmatic subjects without producing the side effects observed following the systemic administration of non-selective NOS inhibitors, and thus provides support for the potential use of iNOS inhibitors to treat a range of inflammatory clinical disorders.

Background: The role of eicosanoids, including leukotrienes (LTs) and prostaglandins (PGs), in chronic obstructive pulmonary disease (COPD) is uncertain. The aim of this study was to investigate whether eicosanoids are measurable in exhaled breath condensate (EBC), a non-invasive method of collecting airway secretions, in patients with stable mild to moderate COPD, and to show possible differences in their concentrations compared with control subjects., Methods: LTB(4), LTE(4), PGE(2), PGD(2)-methoxime, PGF(2alpha), and thromboxane B(2) (TxB(2)) were measured in EBC in 15 healthy ex-smokers, 20 steroid naïve patients with COPD who were ex-smokers, and in 25 patients with COPD who were ex-smokers and who were treated with inhaled corticosteroids. The study was of cross sectional design and all subjects were matched for age and smoking habit., Results: LTB(4) and PGE(2) concentrations were increased in steroid naïve (LTB(4): median 100.6 (range 73.5-145.0) pg/ml, p<0.001; PGE(2): 98.0 (range 57.0-128.4) pg/ml, p<0.001) and steroid treated patients with COPD (LTB(4): 99.0 (range 57.9-170.5) pg/ml, p<0.001; PGE(2): 93.6 (range 52.8-157.0) pg/ml, p<0.001) compared with control subjects (LTB(4): 38.1 (range 31.2-53.6) pg/ml; PGE(2): 44.3 (range 30.2-52.1) pg/ml). Both groups of patients had similar concentrations of exhaled LTB(4) (p=0.43) and PGE(2) (p=0.59). When measurable, LTE(4) and PGD(2)-methoxime concentrations were similar in COPD patients and controls, whereas PGF(2alpha) concentrations were increased in the former. TxB(2)-LI was undetectable in any of the subjects., Conclusions: There is a selective increase in exhaled LTB(4) and PGE(2) in patients with COPD which may be relatively resistant to inhaled corticosteroid therapy.

Chronic neutrophilic airway inflammation is an important feature of cystic fibrosis (CF). Noninvasive inflammatory markers may be useful in monitoring CF. Leukotriene B4 (LTB4) and interleukin (IL)-6 are inflammatory mediators that are increased in chronic neutrophilic inflammation. The aim of this study was to assess whether LTB4 and IL-6 were increased in exhaled breath condensate of CF patients and whether they could be used to monitor inflammation. Twenty patients with CF (13 males, age of 28 +/- 9 years) were recruited together with 15 age-matched healthy subjects (8 males, age 35 +/- 7 years). LTB4 and IL-6 levels were markedly elevated in patients with acute exacerbations (28.8 +/- 4.3 and 8.7 +/- 0.4 pg/ml) compared with control subjects (6.8 +/- 0.7 and 2.6 +/- 0.1 pg/ml, p < 0.0001). We also observed a decrease of exhaled LTB4 and IL-6 concentrations after antibiotic treatment in six patients who were followed until clinically stable (31.1 +/- 4.4 and 9.5 +/- 0.4 pg/ml vs. 18.8 +/- 0.8 and 6.4 +/- 0.2 pg/ml, respectively) and an increase in 15 CF patients infected with Pseudomonas aeruginosa (34.3 +/- 5.0 and 9.3 +/- 0.3 pg/m) compared with those infected with other bacteria (18.3 +/- 0.7 and 6.9 +/- 0.5 pg/ml). These findings suggest that LTB4 and IL-6 levels are increased in exhaled breath condensate of patients with CF during exacerbation and could be used to monitor airway inflammation in these patients.

Background: Exacerbations are an important feature of chronic obstructive pulmonary disease (COPD), accounting for a large proportion of health care costs. They are associated with increased airway inflammation and oxidative stress., Methods: Concentrations of leukotriene B4 (LTB4), a marker of inflammation, and 8-isoprostane, a marker of oxidative stress, were measured in the exhaled breath condensate of 21 patients (11 M) with COPD during an exacerbation and 2 weeks after treatment with antibiotics. In 12 patients who had no further exacerbations these markers were also measured after 2 months., Results: LTB4 concentrations were raised during the COPD exacerbation (mean (SE) 15.8 (1.1) pg/ml and fell after treatment with antibiotics to 9.9 (0.9) pg/ml (p<0.0001). In 12 patients the level of LTB4 fell further from 10.6 (1.1) pg/ml to 8.5 (0.8) pg/ml (p<0.005) after 2 months. In 12 normal age matched subjects the LTB4 levels were 7.7 (0.5) pg/ml. Concentrations of 8-isoprostane were also increased during the exacerbation (13.0 (0.9) pg/ml) and fell after antibiotic treatment to 9.0 (0.6) pg/ml (p<0.0001). In 12 patients there was a further fall from 9.3 (0.7) pg/ml to 6.0 (0.7) pg/ml (p<0.001) after 2 months compared with normal subjects (6.2 (0.4) pg/ml)., Conclusions: Non-invasive markers of inflammation and oxidative stress are increased during an infective exacerbation of COPD and only slowly recover after treatment with antibiotics.

Cigarette smoking induces an inflammatory response in the airways that may play a key role in the pathogenesis of chronic obstructive pulmonary disease. Noninvasive markers of inflammation may, therefore, be useful in monitoring the airways of smokers as well as in the screening of subjects at high risk of developing airway obstruction. The aim of the present study was to determine whether the concentrations of the pro-inflammatory cytokine, interleukin (IL)-6, is increased in the exhaled breath condensate of smokers and whether the number of cigarettes smoked has any influence on the exhaled concentrations. The possibility that exhaled IL-6 levels are related to exhaled carbon monoxide (CO) and lung function has also been explored. Another inflammatory marker, leukotriene (LT), was also measured. Twenty-one smokers (39+/-7 yrs, 13 male) and 14 nonsmokers (45+/-6 yrs, eight male) were recruited. IL-6 and LTB4 levels in the breath condensate were measured with an immunoassay kit and exhaled CO examined by means of a modified electrochemical sensor. Higher IL-6 and exhaled CO concentrations were found in current smokers (5.6+/-1.4 pg x mL(-1) and 16.7+/-5.5 parts per million (ppm)) than in nonsmokers (2.6+/-0.2 pg x mL(-1) and 2.1+/-0.6 ppm). Elevated concentrations of LTB4 were also observed in smokers compared to nonsmokers (9.4+/-0.4 pg x mL(-1) versus 6.1+/-0.3 pg x mL(-1)). In addition, there was a correlation between IL-6 concentrations, the number of cigarettes smoked per day, exhaled CO, LTB4 and lung function. Exhaled interleukin-6 and leukotriene B4 levels may be useful noninvasive markers of airway inflammation in cigarette smokers.

Background: Non-specific interstitial pneumonia (NSIP) and fibrosing alveolitis associated with systemic sclerosis (FASSc) are diseases of unknown aetiology that are characterised by the accumulation of mononuclear cells, followed by the progressive deposition of collagen within the interstitium and subsequent destruction of lung airspace. Better understanding of mediators involved in fibrosis may be useful for early diagnosis and in clinical monitoring of disease progression., Objective: The aim of this study was to investigate the presence of two profibrotic markers, the vitronectin and the endothelin-1 (ET-1) in the airways of NSIP and FASSc patients., Methods: Ten NSIP (6 males, age 57 +/- 2 years) and 15 FASSc (8 males, age 55 +/- 4 years) patients were recruited along with 10 normal subjects (4 male, age 52 +/- 2 years). Vitronectin and ET-1 concentrations were measured in their breath condensate, using a specific enzyme immunoassay., Results: Higher levels of vitronectin and ET-1 were observed in NSIP and FASSc patients [median 92.8 (91.7-93.9) microg/ml; median 8.3 (7.9-9.3) pg/ml] than in control subjects [median 80.3 (89.3-91.4) microg/ml; p < 0.01; median 5.3 (4.9-5.9) pg/ml, p < 0.0001]. We also found increased concentrations of vitronectin in patients with clinical deterioration compared to those remaining stable and in ex-smokers compared to non-smokers and, increased vitronectin and ET-1 in patients treated with steroids compared to untreated patients., Conclusion: These findings justify further studies of vitronectin and ET-1 levels in exhaled breath condensate, as a means of monitoring activity and predicting progression of pulmonary fibrosis., (Copyright 2003 S. Karger AG, Basel)

Nitric oxide (NO), a simple free-radical gas, elicits a diverse range of physiologic and pathophysiologic effects, and plays an important role in pulmonary diseases. Nitrosative stress and nitration of proteins in airway epithelium may be responsible for steroid resistance in asthma and their ineffectiveness in chronic obstructive pulmonary disease (COPD), supporting the potential role of future therapeutic strategies aimed at regulating NO synthesis in asthma and COPD. In this article, we review the potential role of NO modulators (NO synthase inhibitors and NO donors), which, if given on a regular basis, may have clinical benefit in asthma and COPD.

Airway inflammation in asthma is not measured routinely in clinical practice. Fractional exhaled nitric oxide (FE(NO)), a marker of airway inflammation, is increasingly used as an outcome measure in asthma intervention studies and yet the reproducibility of FE(NO) measurements is unknown. The reproducibility, day-to-day, diurnal variation and perception of standardised FE(NO) measurements were examined in 59 subjects (40 children aged 7-13 yrs and 19 adults aged 18-60 yrs), both healthy (n=30) and with mild (n = 29) asthma. FE(NO) was measured on five consecutive days (four measurements on the same day) for adults and twice on the same day for children. The coefficient of reproducibility expressed as the mean pooled standard deviation (n = 59, 675 estimations) was 2.11 parts per billion (ppb) and intraclass correlation coefficient was 0.99 in both children and adults. FE(NO) was significantly higher in asthma subjects (32.3 ppb) than in healthy subjects (16.3 ppb). There was no diurnal or day-to-day variation, or a learning effect, as the result of FE(NO) measurements were identical at results of the beginning and at the end of the study. It was concluded that fractional exhaled nitric oxide measurements are simple, reproducible, free from diurnal and day-to-day variation, and acceptable by both healthy and asthmatic adults and children, as a part of their routine visit to a physician.

In chronic obstructive pulmonary disease (COPD) there is decreased vascularity of the bronchi and inflammation of the airways that may have opposite effects on the regulation of heat loss. Exhaled air temperature increase (delta(e) T) was measured in 23 patients with moderate COPD (18 male, mean age +/- SEM 70 +/- 1 yrs; forced expiratory volume in one second (FEV1) 45 +/- 3%, FEV1/forced vital capacity 54 +/- 4%) and 16 normal volunteers (64 +/- 4 yr) and compared to exhaled nitric oxide (eNO) and inflammatory cells in induced sputum as a marker of airway inflammation. Delta(e) T was measured during a flow- and pressure-controlled single exhalation with a fast-response thermometer. delta(e) T was reduced in patients with COPD (1.86 +/- 0.15 delta C x s(-1)) compared to normal subjects (4.00 +/- 0.26 delta C x s(-1)). There was no difference in delta(e) T between patients treated with inhaled steroids and those who were steroid naïve. Delta(e) T was correlated with eNO (r=0.60) but not with sputum neutrophilia. In COPD patients, delta(e) T was increased (2.26 +/- 0.16 delta C x s(-1)) after the inhalation of 200 microg of albuterol, which is a known vasodilator, indicating that delta(e) T and bronchial blood flow may be correlated. Exhaled temperature increase is reduced in chronic obstructive pulmonary disease patients and is increased by the inhalation of vasodilators and therefore may be related to changes of bronchial blood flow and tissue remodelling.

Background: Primary ciliary dyskinesia (PCD) is associated with chronic airway inflammation resulting in bronchiectasis., Methods: The levels of exhaled nitric oxide (eNO), carbon monoxide (eCO) and nasal NO (nNO) from bronchiectatic patients with PCD (n=14) were compared with those from patients with non-PCD bronchiectasis without (n=31) and with cystic fibrosis (CF) (n=20) and from normal subjects (n=37) to assess the clinical usefulness of these measurements in discriminating between PCD and other causes of bronchiectasis., Results: Exhaled NO levels were lower in patients with PCD than in patients with non-PCD non-CF bronchiectasis or healthy subjects (median (range) 2.1 (1.3-3.5) ppb v 8.7 (4.5-26.0) ppb, p<0.001; 6.7 (2.6-11.9) ppb, p<0.001, respectively) but not lower than bronchiectatic patients with CF (3.0 (1.5-7.5) ppb, p>0.05). Nasal levels of nNO were significantly lower in PCD patients than in any other subjects (PCD: 54.5 (5.0-269) ppb, non-PCD bronchiectasis without CF: 680 (310-1000) ppb, non-PCD bronchiectasis with CF: 343 (30-997) ppb, control: 663 (322-1343) ppb). In contrast, eCO levels were higher in all patient groups than in control subjects (PCD: 4.5 (3.0-24.0) ppm, p<0.01, other bronchiectasis without CF: 5.0 (3.0-15.0) ppm, p<0.001; CF: 5.3 (2.0-23.0) ppm, p<0.001 v 3.0 (0.5-5.0) ppm). Low values in both eNO and nNO readings (<2.4 ppb and <187 ppb, respectively) identified PCD patients from other bronchiectatic patients with a specificity of 98% and a positive predictive value of 92%., Conclusion: The simultaneous measurement of eNO and nNO is a useful screening tool for PCD.

Primary ciliary dyskinesia (PCD) presents to general practitioners with symptoms pertinent to a variety of specialists because of the involvement of ciliated epithelium in the upper/lower respiratory tract, ears, eyes and genital tract. There is no easy, reliable screening test for PCD, and thus, the majority of patients remain undiagnosed. Nitric oxide (NO) is measurable in nasal air of normal subjects and found to be low in cystic fibrosis (CF) and very low in PCD. Recently, it was suggested to play an important role in regulating ciliary motility. The aim of this study was to evaluate whether measurements of nasal NO could be used to screen for PCD. Nasal NO was measured from the nasal cavity by a chemiluminescence analyser in subjects with PCD, healthy controls, CF, idiopathic bronchiectasis, Young's syndrome and lone sinusitis. Nasal NO was significantly lower in PCD (64.0+/-36.6) compared with normal controls (759+/-145.8), idiopathic bronchiectasis (734+/-163.7), CF (447.5+/-162.6), lone sinusitis (1487+/-734) and Young's syndrome (644+/-129.9). Nasal NO was also significantly lower in PCD than CF patients. Measurement of nasal nitric oxide may therefore be used clinically in various specialities to screen suspected patients for primary ciliary dyskinesia.

Chronic inflammation is a critical feature of chronic obstructive pulmonary disease, cystic fibrosis, and asthma. This inflammation is associated with the increased production of reactive oxygen species or oxidative stress in the lungs. Oxidative stress may have several adverse effects and may amplify the inflammatory process; however, monitoring oxidative stress is difficult and may not be reflected by changes in blood markers. We have therefore developed several noninvasive markers in the exhaled breath that may indicate oxidative stress in the lungs, and we studied these in relationship to the severity of chronic inflammatory lung diseases. We analyzed the exhaled breath for the content of nitric oxide as a marker of inflammation, carbon monoxide as a marker of oxidative stress, and ethane, which is one of the end products of lipid peroxidation. In addition, we measured the concentration of markers of oxidative stress such as isoprostanes in exhaled breath condensate. Our results confirm that there are increased inflammation, oxidative stress, and lipid peroxidation in lung disease, as shown by elevated levels of nitric oxide, carbon monoxide, and ethane, respectively. The finding of lower levels of these gases in patients on steroid treatment and of higher levels in those with more severe lung disease, as assessed by lung function tests and clinical symptoms, reinforces the hypothesis that the noninvasive measurement of exhaled gases maybe useful in monitoring the underlying pathologic pathways of lung disease. Longitudinal studies are required to assess the clinical usefulness of these measurements in the monitoring of chronic inflammatory lung disease.

The aim of this study was to quantify lung oxidant stress after short-term ozone exposure as reflected by 8-isoprostane concentrations in exhaled breath condensate (EBC) and to investigate the effects of inhaled budesonide on this response. 8-Isoprostane is a prostaglandin-F(2 alpha) isomer that is formed in vivo by free radical-catalyzed peroxidation of arachidonic acid. EBC is a noninvasive method to collect airway secretions. We undertook a double-blind, randomized, placebo-controlled, crossover study with inhaled budesonide (800 microg) or placebo twice daily for 2 weeks prior to ozone exposure (400 parts per billion) for 2 h in nine healthy nonsmokers. Exhaled 8-isoprostane was measured by an enzyme immunoassay. 8-Isoprostane was increased 4 h after ozone exposure compared to pre-exposure values in both placebo (36.9 +/- 3.9 pg/ml, mean +/- SEM, vs. 16.9 +/- 0.7 pg/ml; p <.001) and budesonide groups (33.4 +/- 2.6 pg/ml vs. 15.8 +/- 0.3 pg/ml; p <.001). Pretreatment with budesonide did not affect the increases in 8-isoprostane (mean differences 3.4 pg/ml, 95% CI -8.9 to 15.7, p =.54). Short-term ozone exposure causes acute increase in lung oxidative stress as reflected by exhaled 8-isoprostane. This increase is resistant to pretreatment with a high dose of inhaled budesonide.

Cysteinyl leukotrienes (cys-LTs; LTC4, LTD4, and LTE4) are generated predominantly by mast cells and eosinophils and induce airway smooth muscle contraction, microvascular leakage, and mucous hypersecretion whereas leukotriene B4 (LTB4) is a potent chemoattractant of neutrophils. We measured cys-LTs and LTB4 in exhaled breath condensate from children aged 7-14 years including healthy nonatopic children (n = 11) and children with mild intermittent asthma (steroid naive, n = 11), mild persistent asthma (low-dose inhaled steroid treatment, n = 13), or moderate to severe persistent asthma (high-dose inhaled steroid treatment, n = 13). Exhaled LTB4 levels were increased in patients with mild and moderate to severe persistent asthma compared with patients with mild intermittent asthma (126.0 +/- 8.8 and 131.9 +/- 7.1 versus 52.7 +/- 3.8 pg/ml, p < 0.001 and p < 0.0001) and normal subjects (126.0 +/- 8.8 and 131.9 +/- 7.1 versus 47.9 +/- 4.1 pg/ml, p < 0.0001). Elevated exhaled cys-LT levels were found in patients with mild and moderate to severe persistent asthma compared with normal subjects (27.9 +/- 2.8 and 31.5 +/- 4.5 versus 18.5 +/- 0.5 pg/ml, p < 0.01 and p < 0.05). There was an inverse correlation between exhaled cys-LTs and LTB4 in patients with mild persistent asthma. We conclude that exhaled cys-LTs and LTB4 may be noninvasive markers of airway inflammation in pediatric asthma.

Study Objectives: Obstructive sleep apnea (OSA) is characterized by repeated episodes of upper airways obstruction during sleep that result in episodes of hypoxia. An increase of systemic biomarkers of inflammation and oxidative stress has been found in patients with OSA and obesity., Design: The aim of this study was to measure the levels of markers of inflammation (interleukin [IL]-6) and oxidative stress (8-isoprostane) in the exhaled breath condensate of OSA and obese patients., Patients and Methods: Eighteen OSA patients (13 men; mean [+/- SEM] age, 44 +/- 7 years), 10 obese subjects (4 men; mean age, 39 +/- 8 years), and 15 healthy age-matched subjects (8 men; mean age, 42 +/- 4 years) were recruited. IL-6 and 8-isoprostane were measured in exhaled breath condensate by a specific enzyme immunoassay kit., Measurements and Results: Higher concentrations of IL-6 were found in OSA patients (8.7 +/- 0.3 pg/mL) than in healthy control subjects (1.6 +/- 0.1 pg/mL; p < 0.0001). Obese subjects also had higher levels than healthy control subjects, but lower levels than OSA patients (2.1 +/- 0.2 pg/mL, p < 0.05 and p < 0.0001 respectively). Furthermore, 8-isoprostane levels were found to be higher in OSA patients (7.4 +/- 0.7 pg/mL) than in obese subjects (5 +/- 0.3 pg/mL; p = 0.4) and healthy subjects (4.5 +/- 0.5 pg/mL; p < 0.005). We found a positive correlation between these two markers and neck circumference and apnea/hypopnea index., Conclusions: These findings suggest that inflammation and oxidative stress are characteristic in the airways of OSA patients but not in obese subjects, and that their levels depend on the severity of the OSA. The measurement of IL-6 and 8-isoprostane levels may prove to be useful in screening and monitoring obese patients who have a high risk of developing OSA.

Background: Dose dependent anti-inflammatory effects of inhaled corticosteroids in asthma are difficult to demonstrate in clinical practice. The anti-inflammatory effect of low dose inhaled budesonide on non-invasive exhaled markers of inflammation and oxidative stress were assessed in patients with mild asthma., Methods: 28 patients entered a double blind, placebo controlled, parallel group study and were randomly given either 100 or 400 micro g budesonide or placebo once daily, inhaled from a dry powder inhaler (Turbohaler), for 3 weeks followed by 1 week without treatment. Exhaled nitric oxide (NO), exhaled carbon monoxide (CO), nitrite/nitrate, S-nitrosothiols, and 8-isoprostanes in exhaled breath condensate were measured four times during weeks 1 and 4, and once a week during weeks 2 and 3., Results: A dose-dependent speed of onset and cessation of action of budesonide was seen on exhaled NO and asthma symptoms. Treatment with 400 micro g/day reduced exhaled NO faster (-2.06 (0.37) ppb/day) than 100 micro g/day (-0.51 (0.35) ppb/day; p<0.01). The mean difference between the effect of 100 and 400 micro g budesonide was -1.55 ppb/day (95% CI -2.50 to -0.60). Pretreatment NO levels were positively related to the subsequent speed of reduction during the first 3-5 days of treatment. Faster recovery of exhaled NO was seen after stopping treatment with budesonide 400 micro g/day (1.89 (1.43) ppb/day) than 100 micro g/day (0.49 (0.34) ppb/day, p<0.01). The mean difference between the effect of 100 and 400 micro g budesonide was 1.40 ppb/day (95% CI -0.49 to 2.31). Symptom improvement was dose-dependent, although symptoms returned faster in patients treated with 400 micro g/day. A significant reduction in exhaled nitrite/nitrate and S-nitrosothiols after budesonide treatment was not dose-dependent. There were no significant changes in exhaled CO or 8-isoprostanes in breath condensate., Conclusion: Measurement of exhaled NO levels can indicate a dose-dependent onset and cessation of anti-inflammatory action of inhaled corticosteroids in patients with mild asthma.

Exhaled breath condensate analysis for noninvasive quantification of airway inflammation in asthma is a potentially useful research tool in children. There is an imbalance between T-helper (Th)-2 cells, which secrete interleukin (IL)-4, and Th1 cells, which secrete interferon (IFN)-gamma, in asthma. We measured concentrations of IL-4 and IFN-gamma in breath condensates of 37 children (11 normal, 12 steroid-naive, and 14 steroid-treated children with asthma). Exhaled IFN-gamma was significantly lower in steroid-naive and steroid-treated children with asthma compared with normal control subjects (3.7 +/- 0.2 versus 5.1 +/- 0.4 pg/ml, p < 0.01 and 4.1 versus 5.1 pg/ml, p < 0.05). By contrast, mean exhaled IL-4 was elevated in asthma (53.7 +/- 4.2 pg/ml) compared with normal children (35.7 +/- 6.2 pg/ml, p < 0.05) and concentrations were lower with steroid treatment (37.5 +/- 5.6 pg/ml, p < 0.05). Exhaled IL-4 was significantly lower in children with asthma on more than 600 microg inhaled steroid/day. The IL-4/IFN-gamma ratio was significantly greater in children with asthma compared with control children and the children with asthma on inhaled steroid therapy. We have shown for the first time that IFN-gamma and IL-4 can be assayed in exhaled breath condensate and shows an increased ratio of IL-4/IFN-gamma, consistent with predominance of Th2 cells in airways of children with asthma. Exhaled breath condensate analysis may have a useful role in studying allergic inflammation in childhood asthma.

In asthma there is increased vascularity of the airway mucosa, altering heat loss in the airways. We hypothesized that as a result of these inflammatory changes, asthmatic patients would have elevated rates of the exhaled air temperature increase (Deltae degrees T). We measured Deltae degrees T in 18 asthmatic subjects (mean age +/- SEM, 38 +/- 8 yr; 9 male, FEV(1) 74 +/- 10%) and 16 normal volunteers (mean age +/- SEM, 33 +/- 3 yr) and compared it with exhaled nitric oxide (NO) as a marker of inflammation. Deltae degrees T was measured during a flow- and pressure-controlled single exhalation with a fast response (1 ms) thermometer. The end-expiratory plateau temperature was similar in asthmatic compared with normal subjects (35.75 +/- 0.6 degrees C and 34.45 +/- 0.8 degrees C, p > 0.05). However, Deltae degrees T was greater in asthmatic subjects (8.17 +/- 0.83 degrees C/s and 4.12 +/- 0.41 degrees C/s, p < 0.01) and correlated with NO (r = 0.65, p = 0.034). Deltae degrees T was increased in normal subjects (from 4.28 +/- 0.8 degrees C/s to 7.60 +/- 0.5 degrees C/s, p < 0.01) but not in asthmatic patients (from 8.28 +/- 0.41 degrees C/s to 8.80 +/- 0.41 degrees C/s, p > 0.05) after the inhalation of albuterol, indicating that Deltae degrees T may reflect bronchial blood flow. Asthmatic subjects have elevated Deltae degrees T. This may represent a novel, noninvasive means of measuring airway blood flow and inflammation in asthma.

Analysis of various biomarkers in exhaled breath allows completely non-invasive monitoring of inflammation and oxidative stress in the respiratory tract in inflammatory lung diseases, including asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), bronchiectasis and interstitial lung diseases. The technique is simple to perform, may be repeated frequently, and can be applied to children, including neonates, and patients with severe disease in whom more invasive procedures are not possible. Several volatile chemicals can be measured in the breath (nitric oxide, carbon monoxide, ammonia), and many non-volatile molecules (mediators, oxidation and nitration products, proteins) may be measured in exhaled breath condensate. Exhaled breath analysis may be used to quantify inflammation and oxidative stress in the respiratory tract, in differential diagnosis of airway disease and in the monitoring of therapy. Most progress has been made with exhaled nitric oxide (NO), which is increased in atopic asthma, is correlated with other inflammatory indices and is reduced by treatment with corticosteroids and antileukotrienes, but not (beta 2-agonists. In contrast, exhaled NO is normal in COPD, reduced in CF and diagnostically low in primary ciliary dyskinesia. Exhaled carbon monoxide (CO) is increased in asthma, COPD and CF. Increased concentrations of 8-isoprostane, hydrogen peroxide, nitrite and 3-nitrotyrosine are found in exhaled breath condensate in inflammatory lung diseases. Furthermore, increased levels of lipid mediators are found in these diseases, with a differential pattern depending on the nature of the disease process. In the future it is likely that smaller and more sensitive analyzers will extend the discriminatory value of exhaled breath analysis and that these techniques may be available to diagnose and monitor respiratory diseases in the general practice and home setting.

The concentration of carbon monoxide (CO) in exhaled air is increased in patients with asthma, bronchiectasis and upper respiratory tract viral infections. However there is no information about the level of CO in patients with lower respiratory tract infection. We studied a group of 35 patients (22 males) aged 45 +/- 3 (SEM) years with cough productive of purulent phlegm and pyrexia in a general practice setting. All were non-smokers or ex-smokers and none had a previous history of respiratory problems or diabetes. We measured CO level in exhaled air before and after a course of antibiotics. Therapy was deemed successful when patient no longer complained of cough productive of purulent phlegm. Twenty-eight of 35 patients had elevated CO level at their initial visit. Twenty-two out of 35 patients reported clinical improvement after antibiotic treatment and this was associated with a fall in exhaled CO level from 5.2 +/- 0.5 ppm to 2.3 +/- 0.3 ppm (P < 0.0001). We suggest that simple CO measurements in exhaled air can detect the inflammatory process within the airways caused by infection and that a repeat measurement can be used to assess the nature of inflammation.

Study Objectives: To investigate whether exhaled carbon monoxide (CO) and nitric oxide (NO) could be used as noninvasive in vivo biomarkers of oxidative stress in the lungs of patients with COPD., Design: Single-center cross-sectional study., Patients: Ten healthy nonsmokers, 12 smokers, 15 stable ex-smokers with COPD, and 15 stable current smokers with COPD., Interventions: Subjects attended the outpatient clinic on one occasion for pulmonary function tests and exhaled CO and NO measurements., Measurements and Results: Mean (+/- SEM) CO levels in ex-smokers with COPD were higher (7.4 +/- 1.9 ppm; p < 0.05) than in nonsmoking control subjects (3.0 +/- 0.3 ppm) but were lower than in current smokers with COPD (20.0 +/- 2.6 ppm; p < 0.001). There was no correlation between exhaled CO and NO. There was no correlation between CO and lung function tests in any group of patients. Exhaled NO was higher in ex-smokers with COPD (12.0 +/- 1.0 parts per billion [ppb]; p < 0.001) than in healthy nonsmokers (6.5 +/- 0.6 ppb) and in current smokers with COPD (7.6 +/- 1.1 ppb; p < 0.01) compared to healthy smokers (3.3 +/- 0.4 ppb). Ex-smokers with COPD had higher exhaled NO levels than did current smokers with COPD (p < 0.001) There was a negative correlation between exhaled NO and FEV(1) in both ex-smokers with COPD (r = -0.60; p < 0.02) and current smokers with COPD (r = -0.59; p < 0.02)., Conclusion: The measurement of exhaled CO and NO may represent a new method for the noninvasive monitoring of airway inflammation and oxidant stress in COPD ex-smokers. Exhaled CO and NO are strongly affected by cigarette smoking, which limits their usefulness as biomarkers in current smokers.

Exhaled markers of inflammation allow completely noninvasive monitoring of inflammation and oxidative stress in the respiratory tract in inflammatory lung diseases, including asthma, chronic obstructive pulmonary disease, cystic fibrosis, bronchiectasis and interstitial lung diseases. Such noninvasive techniques are simple to perform, may be repeated frequently and can be applied in children, including neonates and patients with severe disease in whom more invasive procedures are not possible. Several volatile chemicals can be measured in the breath (nitric oxide, carbon monoxide, hydrocarbons), and many nonvolatile molecules (mediators, oxidation and nitration products, proteins) may be measured in exhaled breath condensate.

Background: Cigarette smoking reduces the level of exhaled nitric oxide (NO) in healthy subjects, although the mechanism is unclear. NO is a highly reactive molecule which can be oxidised or complexed with other biomolecules, depending on the microenvironment. The stable oxidation end products of NO metabolism are nitrite and nitrate. This study investigated the effect of smoking on NO metabolites in exhaled breath condensate., Methods: Fifteen healthy current smokers were recruited together with 14 healthy non-smokers. Measurement of exhaled NO, lung function, and collection of exhaled breath condensate were performed. Nitrite, nitrite + nitrate, S-nitrosothiols, and nitrotyrosine levels were measured. The effect of inhaling two cigarettes in smokers was also evaluated. The mean level of exhaled NO in smokers was significantly lower than in non-smokers (4.3 (0.3) ppb v 5.5 (0.5) ppb, p<0.05)., Results: There was no difference in the levels of nitrite, nitrite + nitrate, S-nitrosothiols, and nitrotyrosine in the exhaled breath condensate at the baseline visit between smokers and non-smokers. After smoking, nitrite + nitrate levels were significantly but transiently increased (from 20.2 (2.8) microM to 29.8 (3.4) microM, p<0.05). There was no significant change in the levels of exhaled NO, nitrite, S-nitrosothiols, or nitrotyrosine 30 and 90 minutes after smoking., Conclusions: These findings suggest that acute smoking can increase the level of nitrate, but not nitrite, S-nitrosothiols, or nitrotyrosine in breath condensate. The deleterious effect of oxidant radicals induced by smoking may contribute to the epithelial damage of airways seen in smokers.

Exhaled nitric oxide (ENO), a marker of inflammation in airway diseases is decreased in cystic fibrosis (CF) patients, perhaps because nitric oxide (NO) is metabolized to oxidative end-products. A stable product, 3-nitrotyrosine, may indicate local formation of reactive nitrogen species. Whether NO metabolites in exhaled breath condensate may be increased in CF patients was investigated. The fractional concentration of ENO (Feno), nitrotyrosine and oxides of nitrogen in exhaled breath condensate from 36 stable CF patients were compared to 14 normal subjects using an enzyme immunoassay and fluorescence assay. Nitrotyrosine levels in breath condensate were increased significantly in stable CF patients, compared with normal subjects (25.3 +/- 1.5 versus 6.3 +/- 0.8 ng x mL(-1), p<0.0001). There was an inverse correlation between the levels of nitrotyrosine and the severity of lung disease. Feno levels were significantly lower in CF patients than in normal subjects (4.4 +/- 0.3 versus 5.6 +/- 0.4 (parts per billion), p<0.05). No correlation was found between nitrotyrosine and Feno levels in CF. There was no significant difference in the levels of nitrite and nitrate between CF patients and normals. The elevation in nitrotyrosine may reflect increased formation of reactive nitrogen species such as peroxynitrite or direct nitration by granulocyte peroxidases, indicating increased oxidative stress in airways of cystic fibrosis patients.

Nitrosothiols (RS-NOs) are formed by interaction of nitric oxide (NO) with glutathione and may limit the detrimental effect of NO. Because NO generation is increased in airway inflammation, we have measured RS-NOs in exhaled breath condensate in patients with asthma, cystic fibrosis, or chronic obstructive pulmonary disease (COPD). We also measured exhaled NO and nitrite (NO(2-)) in the same subjects. RS-NOs were detectable in exhaled breath condensate of all subjects. RS-NOs were higher in subjects with severe asthma (0.81 +/- 0.06 microM) when compared with normal control subjects (0.11 +/- 0.02 microM, p < 0.01) and with subjects with mild asthma (0.08 +/- 0.01 microM, p < 0.01). Elevated RS-NOs values were also found in patients with cystic fibrosis (0.35 +/- 0.07 microM, p < 0.01), in those with COPD (0.24 +/- 0.04 microM, p < 0.01) and in smokers (0.46 +/- 0.09 microM, p < 0.01). In current smokers there was a correlation (r = 0.8, p < 0.05) between RS-NOs values and smoking history (pack/year). We also found elevated concentrations of NO(2-) in patients with severe asthma, cystic fibrosis, or COPD, but not in smokers or patients with mild asthma. This suggests that exhaled NO(2-) is less sensitive than exhaled RS-NOs. This study has shown that RS-NOs are detectable in exhaled breath condensate of healthy subjects and are increased in patients with inflammatory airway diseases. As RS-NOs concentrations in exhaled breath condensate vary in the different airway diseases and increase with the severity of asthma, their measurement may have clinical relevance as a noninvasive biomarker of nitrosative stress.

Oxidative stress is implicated in the pathogenesis and progression of asthma (1,2), chronic obstructive respiratory disease (COPD) (3), and cystic fibrosis (4). Reactive oxygen species (ROS) are unstable compounds with unpaired electrons, capable of initiating oxidation. Several of the inflammatory cells which participate in the inflammatory response, such as macrophages, neutrophils, and eosinophils release increased amounts of ROS (1,5) exceeding the already reduced tissue antioxidant defences of asthmatic and COPD patients (2).

Nitric oxide (NO) can be detected in the exhaled air and the concentration of exhaled NO is increased in patients with airway inflammation such as asthma and bronchiectasis. This suggests that exhaled NO may provide a noninvasive means of monitoring inflammation in the respiratory tract.

Ethane is a product of lipid peroxidation as a result of oxidative stress and can be detected in the exhaled air. Oxidative stress plays a role in the pathogenesis of asthma. We measured exhaled ethane in 26 asthmatic subjects (mean age +/- SEM, 38 +/- 8 yr; 15 male, FEV(1) 60 +/- 4%) and compared it with exhaled nitric oxide (NO) measured by chemiluminescence, a noninvasive marker of oxidative stress and inflammation. Exhaled ethane was collected during a flow- and pressure-controlled exhalation into a reservoir discarding dead space air contaminated with ambient air. A sample of the expired air was analyzed by chromatography. Exhaled ethane levels were elevated in asthma patients not receiving steroid (n = 12, 2.06 +/- 0.30 ppb) compared with steroid-treated patients (n = 14, 0.79 +/- 0.10 ppb, p < 0.01) and to 14 nonsmoking control subjects (0.88 +/- 0.09 ppb, p < 0.05). In patients not receiving steroid treatment there was a positive correlation between exhaled ethane and NO (r = 0.55, p < 0.05) and air trapping assessed by the ratio of residual volume to total lung capacity (RV/ TLC) (r = 0.60, p < 0.05). In addition, untreated patients with FEV(1) < 60% predicted value had higher concentrations of ethane (2.86 +/- 0.37 ppb) compared with less obstructed patients (FEV(1) > 60%, 1.26 +/- 0.12 ppb, p < 0.05). NO concentrations were higher in patients not on steroid treatment (14.7 +/- 1.7 ppb) than in steroid-treated patients (8.6 +/- 0.5 ppb, p < 0.05). Exhaled ethane is elevated in asthma, reduced in steroid-treated patients, and correlates with NO and airway obstruction. It may be a useful noninvasive marker of oxidative stress.

The reaction of nitric oxide (NO) and superoxide anions (O(2)(-)) in the airway results in the formation of peroxynitrite, a highly reactive oxidant species. Peroxynitrite reacts with tyrosine residues in proteins to form the stable product nitrotyrosine. We investigated whether nitrotyrosine in exhaled breath condensates may be increased in patients with asthma. Four groups of nonsmoking subjects were studied. We measured exhaled NO, nitrotyrosine, and leukotrienes concentrations in breath condensate in healthy nonatopic subjects (n = 15) and in patients with mild asthma (steroid naive, n = 15), moderate asthma (inhaled steroid treatment, n = 12), and severe asthma (oral steroid treatment, n = 12). Exhaled NO was increased significantly in patients with mild (19.2 +/- 2.7 ppb, p < 0.01) and moderate asthma (14.0 +/- 1.53 ppb, p < 0.05), as compared with normal control (6.58 +/- 0.61 ppb). The levels of LTC(4)/D(4)/E(4) and LTB(4) were increased significantly in patients with moderate and severe asthma treated with steroids. Nitrotyrosine concentrations were detectable (6.3 +/- 0.8 ng/ml) in breath condensate of normal subjects, and were increased significantly in patients with mild asthma (15.3 +/- 2.0 ng/ml, p < 0.01). However, the levels of nitrotyrosine in exhaled condensate were lower in patients with moderate (5.0 +/- 0.6 ng/ml) and severe asthma (3.3 +/- 0.6 ng/ml, p < 0.05). There was a significant correlation between nitrotyrosine in breath condensate and exhaled NO in patients with mild asthma (r = 0.65, p < 0.05). We conclude that nitrotyrosine formation in exhaled breath condensates may be a marker of oxidative stress in airways of asthma.

Most of the studies linking chronic obstructive pulmonary disease (COPD) with oxidative stress are in vitro, using invasive techniques, or measuring systemic oxidative stress. The aim of this study was to quantify oxidative stress in the lungs in patients with COPD and in healthy smokers, as reflected by 8-isoprostane concentrations in breath condensate. This is a noninvasive method to collect airway secretions. 8-Isoprostane is a prostaglandin-F(2alpha) isomer that is formed in vivo by free radical-catalyzed peroxidation of arachidonic acid. We also studied the acute effect of smoking on exhaled 8-isoprostane in healthy smokers. Exhaled 8-isoprostane was measured by a specific enzyme immunoassay in 10 healthy nonsmokers and 12 smokers, 25 COPD ex-smokers, and 15 COPD current smokers. 8-Isoprostane concentrations were similar in COPD ex-smokers (40 +/- 3.1 pg/ml) and current smokers (45 +/- 3.6 pg/ ml) and were increased about 1.8-fold compared with healthy smokers (24 +/- 2.6 pg/ml, p < 0.001), who had 2.2-fold higher 8-isoprostane than healthy nonsmokers (10.8 +/- 0.8 pg/ml, p < 0.05). Smoking caused an acute increase in exhaled 8-isoprostane by about 50%. Our study shows that free radical production is increased in patients with COPD and that smoking causes an acute increase in oxidative stress.

Ethane is a product of lipid peroxidation and can be measured in the exhaled air as an index of oxidative stress. Oxidant/antioxidant imbalance is important in the pathogenesis of chronic obstructive pulmonary disease (COPD). Therefore, we measured exhaled ethane in 22 patients with COPD (mean age +/- SEM, 59 +/- 8 yr; 19 male) and compared it with other noninvasive markers of oxidative stress and inflammation such as carbon monoxide (CO), measured electrochemically, and nitric oxide (NO), measured by chemiluminescence. Exhaled ethane was collected during a flow and pressure-controlled exhalation into a reservoir, discarding dead space air contaminated with ambient air. A sample of the collected expired air was analyzed by chromatography. Compared with normal subjects (n = 14; eight men; age, 33 +/- 2.8 yr), patients with COPD not on steroid treatment (n = 12; FEV(1), 58 +/- 6%) had elevated levels of exhaled ethane (2.77 +/- 0.25 and 0.88 +/- 0.09 ppb, respectively, p < 0.05), CO (5.96 +/- 0.50 and 2.8 +/- 0.25 ppm, p < 0.05) and NO (11.86 +/- 0.53 and 6.77 +/- 0.50 ppb, p < 0.05) levels. Ethane was correlated to FEV(1) (r = -0.67, p < 0.05). Patients receiving steroid treatment (n = 10; FEV(1), 56 +/- 2%) had lower levels of ethane (0.48 +/- 0.05 ppb) than did steroid-treated patients, whereas CO (5.99 +/- 0.63 ppm) and NO (9.11 +/- 0.53 ppb) levels were similar in the two treatment groups. Exhaled ethane is elevated, correlates with FEV(1), and is significantly lower in patients treated with steroids, so it may be complementary to the use of NO and CO in assessing and monitoring oxidative stress in COPD.

Ethane is produced from lipid peroxidation and can be measured in the exhaled air. Cystic fibrosis (CF) is characterized by recurrent respiratory infections, release of reactive oxygen species by inflammatory cells, and increased oxidative stress. We measured exhaled ethane in 23 CF subjects (mean age +/- SEM, 21 +/- 4 yr; 10 male, FEV(1) 62 +/- 4%) and compared it with two other noninvasive markers of oxidative stress and inflammation, carbon monoxide (CO) and nitric oxide (NO). Exhaled ethane was collected during a flow and pressure-controlled exhalation into a reservoir discarding dead space air contaminated with ambient air. A sample (2 ml) of the expired air was analyzed by chromatography. Ethane levels were elevated in patients not on steroids (n = 13, 1.99 +/- 0.20 ppb) compared with steroid-treated patients (n = 10, 0.67 +/- 0.09 ppb, p < 0.01) and with 14 nonsmoking control (8 men, age 33 +/- 2.8 yr) subjects (0.82 +/- 0.40 ppb, p < 0.05). In patients not on steroid treatment ethane was correlated to airway obstruction as assessed by the ratio of residual volume to total lung capacity (RV/ TLC) (r = 0. 66, p < 0.05) and exhaled CO (r = 0.65, p < 0.05). CO concentrations were also higher in patients not on steroid treatment (3.4 +/- 0.2 ppm) than in steroid-treated patients (2.6 +/- 0.1 ppm, p < 0.05), whereas NO concentrations were not influenced by steroid treatment (3.0 +/- 0.4 ppm and 2.9 +/- 0.2 ppm, p > 0.05) and were lower than in a control group (7.0 +/- 0.4 ppb, p < 0.05). Exhaled ethane is elevated in CF, reduced in steroid-treated patients and correlates with CO and RV/TLC; therefore, it may be a useful noninvasive marker of oxidative stress.

Study Objectives: Inducible nitric oxide synthase (iNOS) is upregulated in a number of inflammatory lung conditions, and exhaled nitric oxide (NO) concentration is increased. However, previous studies in children with cystic fibrosis (CF) have shown that exhaled NO is reduced. The purpose of this investigation was to study exhaled NO concentration in adults with CF, and to investigate the effect of CF genotype and respiratory tract infection on this measurement., Design: Exhaled and nasal NO levels were measured in 54 adult CF subjects and 37 healthy nonsmoking age-matched subjects using a chemiluminesence analyzer. Spirometry (FEV(1) and FVC), CF genotype, and bacterial colonization were also recorded., Setting: This study was conducted at a national CF center., Results: The mean age of patients was 26.9 years, and the mean FEV(1) was 50.5% predicted (range, 17 to 104%). Nasal NO in the CF patients (mean, 520 parts per billion [ppb]; confidence interval [CI], 452 to 588) was significantly lower (p < 0.001) than in control subjects (987 ppb; CI, 959 to 1,015). Exhaled NO was significantly lower (p < 0. 001) in CF patients (5.0 ppb; CI, 4.1 to 6.1) than in control subjects (7.3 ppb; CI, 6.8 to 7.8). FEV(1) did not correlate with nasal or exhaled NO. No association was observed between genotype and NO values or colonization with Pseudomonas aeruginosa., Conclusions: Despite the airway inflammation that is characteristic of CF, both nasal and exhaled NO were reduced. There was no association with genotype or infection status. As NO has bacteriostatic effects and may augment mucociliary clearance, this observation may be of clinical importance.

Background: Cystic fibrosis is characterised by oxidative stress in the airways. Isoprostanes are prostaglandin isomers formed by free radical catalysed peroxidation of arachidonic acid. 8-Isoprostane is increased in interstitial lung diseases, asthma, chronic obstructive pulmonary disease, and adult respiratory distress syndrome. Exhaled nitric oxide (NO) and carbon monoxide (CO) are biomarkers of inflammation and oxidative stress in the airways, respectively., Methods: Concentrations of 8-isoprostane in the breath condensate of 10 normal subjects and 19 patients with stable cystic fibrosis were measured using an enzyme immunoassay (EIA). Breath condensate is a non-invasive method of collecting airway secretions. Exhaled nitric oxide (NO) and carbon monoxide (CO) levels were measured by a chemiluminescence analyser., Results: Concentrations of 8-isoprostane in the breath condensate of patients with stable cystic fibrosis were increased about threefold compared with normal subjects (42.7 (4.5) pg/ml vs 15.2 (1.7) pg/ml; p<0.005, 95% CI 14.6 to 40.9). 8-Isoprostane concentrations were negatively correlated with forced expiratory volume in one second in patients with cystic fibrosis (r = -0.61; p<0.005). Exhaled CO was also increased in patients with cystic fibrosis compared with normal subjects (6.7 (1.2) ppm vs 2.9 (0.3) ppm; p<0.05, 95% CI 0.2 to 7.4). 8-Isoprostane concentrations were significantly correlated with CO levels (r = 0.66; p<0.002)., Conclusions: The results of this study show that oxidative stress is increased in cystic fibrosis and may be quantified by measuring 8-isoprostane concentrations in breath condensate.

Background: Non-invasive assessment of inflammation is likely to be useful in the management of cystic fibrosis (CF). Exhaled carbon monoxide (CO) concentrations are increased in patients with clinically stable CF. A study was undertaken to determine whether this marker of oxidative damage is further increased during exacerbations of the disease., Methods: Exhaled CO concentrations were measured in 12 healthy non-smoking control subjects (six men) of mean (SE) age 37 (2) years with forced expiratory volume in one second (FEV(1)) 95 (1)% predicted and in 44 patients with CF (20 men) of mean (SE) age 29 (1) years with FEV(1) 56 (3)% predicted using an on-line CO analyser., Results: Twenty nine patients were in a stable condition while 15 had clinically defined respiratory exacerbations (increased cough and production of sputum, change in the quality of the sputum, shortness of breath, sensation of chest congestion, and deterioration of FEV(1)) and represented the unstable group. Exhaled CO concentrations were 2.0 (0.15) ppm in the control group, were increased in the stable CF group to 2.7 (0.13) ppm (differences between means -0.67 (0.22), 95% confidence interval (CI) 0.22 to 1.12, p<0.01) and further increased in the unstable group to 4.8 (0.3) ppm (differences between means -2.15 (0.32), 95% CI 1.50 to 2.79, p<0.001). A significant correlation was found between the deterioration in FEV(1) and exhaled CO concentrations., Conclusions: This study shows that the measurement of exhaled CO is of potential value as an indicator of exacerbations in patients with CF and could be used as a simple method to monitor the course of the disease.

Background: Nitric oxide (NO) plays an important role as an inflammatory mediator in the airways. Inducible NO synthase in the nasal mucosa is upregulated in perennial allergic rhinitis, and nasal NO is reduced after treatment with topical corticosteroids. A previous study has suggested that there is a significant correlation between exhaled NO and sputum eosinophils in patients with asthma., Objective: We investigated the ability of intranasal administration of eotaxin, a potent chemoattractant for eosinophils, to induce eosinophil accumulation and the relationship between eosinophil recruitment in the nasal mucosa and nasal NO production in patients with allergic rhinitis., Methods: Nine patients with allergic rhinitis were studied. Eotaxin or diluent was delivered intranasally in patients by using a metered spray pump. Nasal NO, symptom scores, and the influx of inflammatory cells in nasal lavage fluid were assessed before and after the challenge. Immunoreactivity for inducible NO synthase and nitrotyrosine was evaluated in nasal lavage cells., Results: Eotaxin induced a significant influx of eosinophils (P <.05) with mild symptoms of rhinitis. There was neither significant migration of lymphocytes, basophils, and macrophages into nasal lavage fluid nor a shedding of nasal epithelial cells after eotaxin challenge. Nasal NO was increased significantly (P <.05) 8 hours after eotaxin challenge compared with diluent challenge. Nitrotyrosine immunoreactivity was moderately elevated in nasal epithelial cells after the challenge., Conclusion: We have shown that eotaxin causes chemotaxis of eosinophils with a clinically symptomatic inflammatory response in the nasal mucosa and that eosinophil recruitment accompanies an increase in nasal NO, contributing to oxidative stress.

Objectives: Oxidative stress and inflammation induce the expression of heme oxygenase-1, which produces carbon monoxide (CO), and nitric oxide synthase, which produces nitric oxide (NO). Exhaled CO and NO levels are elevated in asthmatic patients and are decreased after corticosteroid treatment, suggesting that they may be useful as noninvasive markers of airway inflammation., Study Design: We measured forced expiratory volume in the first second, PC(20), and exhaled CO and NO levels in 29 children (18 boys, mean age 11.5 +/- 0.53 years) with asthma of different severity and 40 nonsmoking children without asthma (21 boys, mean age 8.1 +/- 0.35 years). We also studied whether upper respiratory tract infections were associated with elevated exhaled CO., Results: Exhaled CO levels (ppm) were significantly higher (2.17 +/- 0.21) in children with persistent asthma compared with those in children with infrequent episodic asthma (1.39 +/- 0.18, P <.05) and healthy children (1.01 +/- 0.12, P <.001). The CO levels in children with infrequent episodic asthma and the normal control group, however, were not different. In contrast, exhaled NO levels (ppb) were higher in children with persistent asthma (24.2 +/- 5.9, P <.001) and infrequent episodic asthma (14.5 +/- 3.73, P <.05) than in normal subjects (5.1 +/- 0.24), but no significant difference was seen between the 2 asthmatic groups. In healthy children with upper respiratory tract infections (n = 12), exhaled CO concentrations were significantly elevated (2.16 +/- 0.33) during the acute symptomatic phase. No correlation was found between exhaled CO and forced expiratory volume in the first second or PC(20)., Conclusions: Noninvasive measurement of exhaled CO may provide complementary data for assessment of asthma control in children. However, elevated CO levels are nonspecific and may be found in association with an acute viral illness.

Background: Inflammation, oxidative stress, and recurrent pulmonary infections are major aggravating factors in cystic fibrosis. Nitric oxide (NO), a marker of inflammation, is not increased, however, probably because it is metabolised to peroxynitrite. Exhaled carbon monoxide (CO), a product of heme degradation by heme oxygenase 1 (HO-1) which is induced by inflammatory cytokines and oxidants, was therefore tested as a non-invasive marker of airway inflammation and oxidative stress., Methods: Exhaled CO and NO concentrations were measured in 29 patients (15 men) with cystic fibrosis of mean (SD) age 25 (1) years, forced expiratory volume in one second (FEV(1)) 43 (6)%, 14 of whom were receiving steroid treatment., Results: The concentration of exhaled CO was higher in patients with cystic fibrosis (6.7 (0.6) ppm) than in 15 healthy subjects (eight men) aged 31 (3) years (2.4 (0.4) ppm, mean difference 4.3 (95% CI 2.3 to 6.1), p<0.001). Patients not receiving steroid treatment had higher CO levels (8.4 (1.0) ppm) than treated patients (5.1 (0.5) ppm, mean difference 3.3 (95% CI -5.7 to -0.9), p<0.01). Normal subjects had higher NO levels (6.8 (0.4) ppb) than patients with cystic fibrosis (3.2 (0.2) ppb, mean difference 3.8 (95% CI 2.6 to 4.9), p<0.05) and were not influenced by steroid treatment (3.8 (0.4) ppb and 2.7 (0. 3) ppb for treated and untreated patients, respectively, mean difference 0.8 (95% CI -0.6 to 2.3), p>0.05). Patients homozygous for the DeltaF508 CFTR mutation had higher CO and NO concentrations than heterozygous patients (CO: 7.7 (1.8) ppm and 4.0 (0.6) ppm, respectively, mean difference 3.7 (95% CI -7.1 to -0.3), p<0.05; NO: 4.1 (0.5) ppb and 1.9 (0.7) ppb, respectively, mean difference 2.2 (95% CI -3.7 to -0.6), p<0.05)., Conclusions: High exhaled CO concentrations in patients with cystic fibrosis may reflect induction of HO-1. Measurement of exhaled CO concentrations may be clinically useful in the management and monitoring of oxidation and inflammatory mediated lung injury.