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Title: Biophysical, biochemical and cellular markers of airway inflammation in asthma
Author: Noble, Donald D.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2008
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Respiratory heat and moisture loss (RHML) is proposed as a novel biophysical marker of AI. In a cross-sectional study of 23 patients with stable persistent asthma, 19 patients with acute asthma and 18 controls, RHML was significantly elevated in stable asthma (p=<0.01) and correlated with sputum eosinophil percentage (r=0.73; p=<0.01). Paradoxically, RHML was not elevated in acute asthma, and a number of possible explanations are discussed. The exhaled gases nitric oxide (NO) and carbon monoxide (CO), and exhaled breath condensate (EBC) pH and nitrite were examined in a cross-sectional study of 32 patients with stable asthma, 25 patients with acute asthma and 25 controls. NO was significantly increased in stable asthma compared with controls (p=<0.01). EBC pH was significantly lower in stable asthma than controls (p=<0.05) and there was a further decrease in acute asthma (p=<0.01). CO and EBC nitrite were not elevated in stable or acute asthma. Induced sputum differential cell counts were investigated in a cross-sectional study of patients with stable asthma (n=42), acute asthma (n=11), chronic obstructive pulmonary disease (n=26), bronchiectasis (n=14) and healthy controls (n=25). The percentage of eosinophils was significantly greater in stable asthma and acute asthma compared with other groups (p=<0.01). There was no difference in the percentage of eosinophils between patients with mild/moderate asthma and severe asthma. However, sputum neutrophil percentage was higher in severe persistent asthma (p=<0.01). To investigate the sensitivity of these markers to short term changes in airway inflammation, serial measurements were made during the resolution of an acute exacerbation of asthma. Exhaled NO decreased and EBC increased by day 7-9 of an exacerbation. The changes in these markers lagged behind changes in FEV1, suggesting that AI persisted beyond the principal period of bronchoconstriction.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (M.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available