NO Flux (no + flux)

Distribution by Scientific Domains

Selected Abstracts

Alveolar and bronchial nitric oxide output in healthy children

Anna Sepponen MD
Abstract Exhaled nitric oxide (NO) concentration is a marker of pulmonary inflammation. It is usually measured at a single exhalation flow rate. However, measuring exhaled NO at multiple flow rates allows assessment of the flow-independent NO parameters: alveolar NO concentration, bronchial NO flux, bronchial wall NO concentration, and bronchial diffusing capacity of NO. Our aim was to determine the flow-independent NO parameters in healthy schoolchildren and to compare two different mathematical approaches. Exhaled NO was measured at four flow rates (10, 50, 100, and 200 ml/sec) in 253 schoolchildren (7,13 years old). Flow-independent NO parameters were calculated with linear method (flows ,50 ml/sec) and non-linear method (all flows). Sixty-six children (32 boys and 34 girls) with normal spirometry and no history or present symptoms of asthma, allergy, atopy or other diseases were included in the analysis. Median bronchial NO flux was 0.4 nl/sec (mean,,SD: 0.5,,0.3 nl/sec) and median alveolar NO concentration was 1.9 ppb (2.0,,0.8 ppb) with the linear method. Bronchial NO flux correlated positively with height (r,=,0.423; P,<,0.001), FEV1 (r,=,0.358; P,=,0.003), and FVC (r,=,0.359; P,=,0.003). With the non-linear method, median bronchial wall NO concentration was 49.6 ppb (68.0,,53.3 ppb) and bronchial diffusing capacity of NO was 10.0 pl/sec/ppb (11.8,,7.5 pl/sec/ppb). The non-linear method gave lower alveolar NO concentration (1.4 [1.5,,0.7] ppb, P,<,0.001) and higher bronchial NO flux (0.5 [0.6,,0.3] nl/sec, P,<,0.001) than the linear method, but the results were highly correlated between the two methods (r,=,0.854 and r,=,0.971, P,<,0.001). In conclusion, the multiple flow rate method is feasible in children but different mathematical methods give slightly different results. Reference values in healthy children are of value when applying bronchial and alveolar NO parameters in the diagnostics and follow-up of inflammatory lung diseases. Pediatr. Pulmonol. 2008; 43:1242,1248. 2008 Wiley-Liss, Inc. [source]

Flooding induced emissions of volatile signalling compounds in three tree species with differing waterlogging tolerance

ABSTRACT To gain insight into variations in waterlogging responsiveness, net assimilation rate, stomatal conductance, emissions of isoprene and marker compounds of anoxic metabolism ethanol and acetaldehyde, and stress marker compounds nitric oxide (NO), volatile products of lipoxygenase (LOX) pathway and methanol were studied in seedlings of temperate deciduous tree species Alnus glutinosa, Populus tremula and Quercus rubra (from highest to lowest waterlogging tolerance) throughout sustained root zone waterlogging of up to three weeks. In all species, waterlogging initially resulted in reductions in net assimilation and stomatal conductance and enhanced emissions of ethanol, acetaldehyde, NO, LOX products and methanol, followed by full or partial recovery depending on process and species. Strong negative correlations between gs and internal NO concentration and NO flux, valid within and across species, were observed throughout the experiment. Isoprene emission capacity was not related to waterlogging tolerance. Less waterlogging tolerant species had greater reduction and smaller acclimation capacity in foliage physiological potentials, and larger emission bursts of volatile stress marker compounds. These data collectively provide encouraging evidence that emissions of volatile organics and NO can be used as quantitative measures of stress tolerance and acclimation kinetics in temperate trees. [source]

Nitric oxide evaluation in upper and lower respiratory tracts in nasal polyposis

C. Delclaux
Summary Background A decrease in nasal nitric oxide (NO) and an increase in exhaled NO have been demonstrated in patients with nasal polyposis (NP). Objectives The aims were to evaluate the flux of NO from the three compartments of the respiratory tract, namely, upper nasal, lower conducting and distal airways, and to search for relationships between NO parameters and indexes of upper and lower disease activity (bronchial reactivity and obstruction). The effect of medical treatment of polyposis was also evaluated. Methods Seventy patients with polyposis were recruited. At baseline, pulmonary function tests (spirometry, plethysmography, bronchomotor response to deep inspiration using forced oscillation measurement of resistance of respiratory system, methacholine challenge, multiple flow rates of exhaled NO and nasal NO measurements) were performed together with an assessment of polyposis [clinical, endoscopic and computed tomography (CT) scores]. Results Statistical relationships were demonstrated between nasal NO flux and severity scores (clinical: ,=,0.31, P=0.015; endoscopic: ,=,0.57, P<0.0001; CT: ,=,0.46, P=0.0005), and between alveolar NO concentration and distal airflow limitation (FEF25,75, ,=,0.32, P=0.011). Thirty-six patients were assessed after 11 [7,13] (median [interquartile]) months of medical treatment, demonstrating an improvement in clinical and endoscopic scores, an increase in nasal NO flux, a decrease in NO flux from conducting airways, an improvement in the mild airflow limitation (forced expiratory volume in 1 s, FEF25,75, even in non-asthmatic patients) and a decrease in the bronchoconstrictor effect of deep inspiration. Conclusions The medical treatment of NP improves both airway reactivity and obstruction, whatever the presence of asthma, suggesting a functional link between upper and lower airway functions. [source]