 - Current severe illness, including liver and renal failure, major organ allograft, malignancy requiring parenteral chemotherapy that can not be discontinued for the duration of the trial, or any other conditions which would make the subject unsuitable for the study. Subjects with basal cell carcinoma of the skin, in situ carcinoma of the cervix, or non-disseminated stable Kaposis sarcoma may be included in the trial. 