Prognostic Influence of Light Rheography Measurement of Patients With Secondary Raynaud Syndrome With Ulcers on Hands

Inclusion Criteria: * Subjects with Limited or diffuse systemic sclerosis/scleroderma with at least one ulcera at fingertip * Age \> 18 Years * Weight \> 40 Kg Exclusion Criteria: * Sympathectomy * Ulcers due to other condition (PVD, DM, Thromboangiitis obliterans etc.) * Antibiotic concomitant medication * Therapy with Prostanoids within the last 4 weeks * Previous Bosentan therapy * Severe liver and renal insufficiency(creatinin \>2.0 mg/dl;AST/ALT \> 3X UNL) * severe cardiac- pulmonal diseases * Untreated or therapy refractory Hypertension * Noncompliance * Pregnancy or nursing (Pregnancy test required)