1 Julkunen H, Saijonmaa O, Gronhagen-kiska C. et al. Raised plasma concentrations of endothelin-1 in systemic lupus erythematosus. Ann Rheum Dis, 7491,50:526. 2 Kannok, Hirata Y, Emori T, et al. Endothelin and Ray naud’s phenomenon. Am J Med. 1991,90:180. 3 Chubick A, Horsfall AC, Koffler D, et al. An appraisal of test for native DNA antibodies in connective tissue diseases:clinical usefulness of Crithidia luciliae assay. Ann Int Med, 1987,89:186.