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Objective: To study how soluble citrullinated telopeptides of type I and II collagens inhibit the binding of autoantibodies to the respective antigens immobilized onto solid phase, and to use modifications of previous methods to re-analyse rheumatoid arthritis (RA) and control serum samples., Methods: Autoantibody binding was inhibited with normal or citrullinated carboxytelopeptides using enzyme-linked immunosorbent assay (ELISA) methods. Serum samples were available from 120 patients with RA and 81 controls., Results: Autoantibodies that bind normal C-telopeptides were not inhibited with soluble normal or citrullinated telopeptides. However, the antibodies that bind only citrullinated telopeptides could be inhibited with corresponding citrullinated telopeptides. Thus, it is not necessary to study the binding of autoantibodies to normal collagens if the specificity of their binding is assessed by immunological inhibition. For type I telopeptide, there are two arginines, the latter of which, when citrullinated, is important for binding. For type II telopeptide, there is one arginine, which is important when citrullinated. The other amino acids, e.g. the last alanine, have only a slight effect on binding. These improved methods differentiate better between RA patients, who have specific citrullinated autoantibodies, and controls than previous ELISA methods., Conclusions: Based on inhibition assay, it is possible to measure the autoantibodies binding specifically to citrullinated telopeptides of type I and II collagens. When only one assay is involved, variance is decreased and the overall performance is easier than before.

The value of ultrasonography (US), magnetic resonance imaging (MRI), computed tomography (CT) and plain radiography (PR) in detecting bone erosions on the humeral head was evaluated in a study of 26 in-patients (26 shoulders) with rheumatoid arthritis (RA). MRI depicted humeral erosions in 25 (96%), US in 24 (92%), CT in 20 (77%) and PR in 19 (73%) of the 26 shoulders. MRI and US were superior to CT in detecting small erosions. US was the most sensitive method to show surface erosions on the greater tuberosity. US, CT and MRI detected large erosions quite similarly. PR frequently missed small erosions. In the evaluation of early erosions in the rheumatoid shoulder, US and MRI are more sensitive methods than the traditionally used PR. US and MRI are suitable for the evaluation of soft-tissue involvement in the rheumatoid shoulder, but also for the detection of bone erosions of the humeral head.

We evaluated 31 painful shoulders of 30 patients with chronic arthritis by ultrasonography (US) and compared the results with those of magnetic resonance imaging (MRI). Both US and MRI revealed effusion in the subacromial-subdeltoid (SA-SD) bursa, biceps tendon sheath (BTS) and glenohumeral (GH) joint, but MRI was more accurate in depicting joint inflammation because of its ability to visualize synovial hypertrophy. US visualized biceps tendon ruptures equally well as MRI. MRI was better able to reveal full-thickness tear of the supraspinatus tendon, whereas US showed better other changes of the supraspinatus tendon (degeneration or partial-thickness tear). Both of the imaging methods were able to depict erosions of the humeral head, but the locations occasionally differed. Inexpensive and easily available US can be recommended as the first imaging method for the detection of soft-tissue changes in the arthritic shoulder, but in rotator cuff problems both methods may be needed.