Dietary and metabolic nitrate is distributed from the blood to the saliva by active uptake in the salivary glands, and is reduced to nitrite in the oral cavity by the action of certain bacteria. Since it has been reported that nitric oxide may be formed nonenzymatically from nitrite this study aimed to determine whether salivary nitrite could influence measurements of exhaled NO.Ten healthy subjects fasted overnight and ingested 400 mg potassium nitrate, equivalent to~200 g spinach. Exhaled NO and nasal NO were regularly measured with a chemiluminescence technique up to 3 h after the ingestion. Measurements of exhaled NO were performed with a single-breath procedure, standardized to a 20-s exhalation, at a flow of 0.15 L . s -1 , and oral pressure of 8±10 cmH 2 O. Values of NO were registered as NO release rate (pmol . s -1 ) during the plateau of exhalation.Exhaled NO increased steadily over time after nitrate load and a maximum was seen at 120 min (77.0 15.2 versus 31.2 3.0 pmol . s -1 , p<0.01), whereas no increase was detected in nasal NO levels. Salivary nitrite concentrations increased in parallel; at 120 min there was a four-fold increase compared with baseline (1.56 0.44 versus 0.37 0.09 mM, p<0.05). The nitrite-reducing conditions in the oral cavity were also manipulated by the use of different mouthwash procedures. The antibacterial agent chlorhexidine acetate (0.2%) decreased NO release by almost 50% (p<0.01) 90 min after nitrate loading and reduced the preload control levels by close to 30% (p<0.05). Sodium bicarbonate (10%) also reduced exhaled NO levels, but to a somewhat lesser extent than chlorhexidine acetate.In conclusion, salivary nitric oxide formation contributes to nitric oxide in exhaled air and a large intake of nitrate-rich foods before the investigation might be misinterpreted as an elevated inflammatory activity in the airways. This potential source of error and the means for avoiding it should be considered in the development of a future standardized method for measurements of exhaled nitric oxide. Eur Respir J 1999; 13: 327±333. In recent years there has been much interest in measurements of nitric oxide in exhaled air, since increased levels of NO were discovered in exhaled air of asthmatics [1] and enzymatically produced NO was suggested as a marker of inflammation in the respiratory tract [2,3]. However, several factors, such as mixing of NO originally produced in the paranasal sinuses, and variations in the degree of pressure and flow of the exhaled air, have been shown to influence and complicate the measurements [4]. These problems have created a need for a standardized method and a few articles have been published for methodological guidance [3,5]. Furthermore, a novel pathway of nonenzymatic NO production via chemical reduction of nitrite has recently been described [6,7] and this might complicate the methodological approach even further.A variable amount of nitrite, a potential substrate for NO formation, is found in the saliva as a product of nitrate reduction. Th...

The causes of severe childhood asthma are poorly understood. Our aim was to define global patterns of gene expression in children with severe therapy-resistant and controlled asthma.White blood cells were isolated and the global transcriptome profile was characterised using the Affymetrix Human Gene ST 1.0 chip in children with severe, therapy-resistant asthma (n517), controlled asthma (n519) and healthy controls (n518). Receptor expression was studied in separated leukocyte fractions from asthmatic adults (n512).Overall, 1378 genes were differentially expressed between children with severe/controlled asthma and controls. Three significantly enriched Kyoto Encyclopedia of Genes and Genomes pathways were represented: natural killer cell-mediated cytotoxicity (upregulated in controlled asthma); N-glycan biosynthesis (downregulated in severe asthma); and bitter taste transduction receptors (TAS2Rs) (upregulated in severe asthma). Quantitative PCR experiments confirmed upregulation of TAS2Rs in severe asthmatics. TAS2R expression was replicated in leukocytes from adult asthmatics, in which TAS2R agonists also inhibited LPS-induced cytokine release. Significant correlations between expression of TAS2Rs and clinical markers of asthma severity were found in both adults and children.In conclusion, specific gene expression patterns were observed in children with severe, therapy-resistant asthma. The increased expression of bronchodilatory TAS2Rs suggests a new target for the treatment of asthma. @ERSpublications Bitter taste receptors are up-regulated in children with severe asthma, suggesting a new therapeutic target

ObjectiveTo determine whether environmental control using nocturnal temperature controlled laminar airflow (TLA) treatment could improve the quality of life of patients with persistent atopic asthma.DesignRandomised, double-blind, placebo-controlled, parallel-group trial.SettingNineteen European asthma clinics.Participants312 patients aged 7–70 with inadequately controlled persistent atopic asthma.Main outcome measureProportion of patients with an increase of ≥0.5 points in asthma quality of life score after 1 year of treatment.ResultsTLA devices were successfully installed in the bedrooms of 282 (90%) patients included in the primary efficacy analysis. There was a difference in treatment response rate between active (143 of 189, 76%) and placebo (56 of 92, 61%) groups, difference 14.8% (95% CI 3.1 to 26.5, p=0.02).3 In patients aged ≥12, on whom the study was powered, the difference in response rate was similar-active 106 of 143 (74%), placebo 42 of 70 (60%), difference 14.1% (0.6 to 27.7, p=0.059). There was a difference between groups in fractional exhaled nitric oxide change of −7.1 ppb (−13.6 to −0.7, p=0.03). Active treatment was associated with less increase in cat-specific IgE than placebo. There was no difference in adverse event rates between treatment groups.ConclusionInhalant exposure reduction with TLA improves quality of life, airway inflammation and systemic allergy in patients with persistent atopic asthma. TLA may be a treatment option for patients with inadequately controlled persistent atopic asthma.Trial registration numberClinical Trials NCT00986323.

Children with problematic severe asthma (PA) are either difficult to treat because of the presence of aggravating factors or else severely resistant to therapy. We investigated a cohort of school-aged children with PA and compared these children to age-matched peers with controlled persistent asthma (CA). The aims were to characterize features of children suffering from PA and identify children who were severely resistant to therapy. In this cross-sectional, multicenter comparison of children with different manifestations of persistent asthma, PA was defined as insufficient asthma control despite level 4 treatment, according to GINA. The protocol included questionnaires, spirometry, methacholine provocation, measurement of fraction of nitric oxide in exhaled (FE(NO) ) and nasal air, blood sampling for inflammatory biomarkers and atopy, and computerized tomography of sinuses and lungs (in the PA group only). Of the 54 children with PA, 61% had therapy-resistant asthma, with the remaining being difficult to treat because of identified aggravating factors. Children with PA more often had parents with asthma (p=0.003), came from families with a lower socioeconomic status (p=0.01), were less physically active (p=0.04), and had more comorbidity with rhinoconjunctivitis (p=0.01) than did the 39 children with CA. The former also exhibited lower FEV(1) values (p=0.02) and increased bronchial hyper-responsiveness (p=0.01), but there were no differences in atopy (p=0.81) or FE(NO) (p=0.16). A non-invasive protocol, involving a standardized and detailed clinical characterization, revealed distinguishing features of children with PA and enabled the identification of children with therapy-resistant asthma.

Our findings support the hypothesis that subnormal levels of vitamin D are associated with acute wheeze in young children.