Hypotheses: 1) Airway pH regulation is abnormal in severe asthma; 2) In severe asthma, there is formation of cytotoxic nitrogen oxides and loss of beneficial nitrogen oxides in the airways
Specific Aim 1:Test hypothesis that airway pH regulation is abnormal in severe asthma. 1a) Determine the effects of systemic corticosteroids on breath pH in children with severe and mild to moderate asthma. 1b) Examine whether breath condensate pH and other biomarkers of oxidant stress can predict clinical outcomes in children with severe and mild to moderate asthma. 1c) Identify whether increased Th1/Th2 cytokine ratio, and abnormalities in airway glutaminase, G-SNO-reductase, VATPase, and carbonic anhydrase are associated with airway pH disturbance in children with severe asthma. 1d) Test whether rhinovirus infections, which reduce airway pH, persist longer or are more frequent in children with severe asthma than in children with mild to moderate asthma. 1e) Examine the relationship between gastroesophageal reflux and proximal airway pH in children with severe asthma and mild to moderate asthma.
Study Type
OBSERVATIONAL
Enrollment
225
Emory Childrens Center
Atlanta, Georgia, United States
Exhaled Nitric Oxide at Baseline and Over the Observational Period
Exhaled nitric oxide concentrations as measured by collection of exhaled breath into a mylar bag
Time frame: baseline and after 21 days
Reduction in Breath pH
Breath condensate pH was measured by the RTube (trademark) device. This device is a plastic tube with a one-way exhalation valve and a chilled aluminum sleeve. pH (the log of hydrogen ion concentration) was measured using an Orion pH meter and probe calibrated in 4.0, 7.0, and 10.0 pH solutions.
Time frame: baseline and 21 days
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