Effect of in vitro ultraviolet radiation on the binding capacity of anti-DNA and DNA in systemic lupus erythematosus.

The in vitro effects of various doses of ultra violet A (UVA) or UVB irradiation on DNA or anti-DNA as measured by their subsequent binding to anti-DNA or DNA were examined. Sera from 12 patients with active lupus were studied. UVA irradiation at 20-240 J/m2 or UVB irradiation at 2-24 J/m2 did not affect DNA or anti-DNA binding to anti-DNA or DNA, respectively. Modulation of the UV effect on DNA and anti-DNA by adding methylprednisolone, hydroxychloroquine and indomethacin at 10(-6) M did not alter the UV effect. UV light does not exert its effect directly on the binding of anti-DNA to DNA.

Polymyositis with hypokalemia: correction with potassium replacement in the absence of steroids.

A patient presented with typical polymyositis, but also with hypokalemia. Correction of potassium deficit without corticosteroids led to complete resolution of symptoms and laboratory abnormalities. Muscle biopsy performed after correction of the hypokalemia revealed focal fiber necrosis with regeneration and inflammatory infiltrate that contained, among others, many eosinophils. Hypokalemia should be considered in the differential diagnosis of polymyositis even in the face of an inflammatory muscle infiltrate.

Psoriatic arthritis affecting the manubriosternal joint.

Manubriosternal synovitis in the absence of peripheral arthritis or spondylitis, in a patient with pustular psoriasis, is described. The radiologic changes noted on lateral chest radiograph consisted of erosions, sclerosis, and joint space widening. This coincidence of manubriosternal joint arthritis and pustular psoriasis is unusual in western populations.