An Enabling Study to Investigate the Correlation of Biomarkers of the Activity of Inducible Nitric Oxide Synthase (iNOS) With Disease Activity and Treatment Response in Patients With Rheumatoid Arthritis(RA)

This study is being conducted to validate various biomarkers in patients with RA with varying levels of disease severity. Subjects with a diagnosis of rheumatoid arthritis (RA) will be included as controls. The sudy will measure the baseline levels and the intra- and inter-subject variability of exhaled nitric oxide (NO) in patients with inactive/mild and moderate/severe RA on stable therapy or during a course glucocorticoids. In addition exhaled NO levels will be correlated with intra-articular inflammation (power Doppler ultrasonography) as well as markers of systemic inflammation (CRP, ESR).