<qa>  What is the name of the study that would preclude the administration of natalizuma- History of, or abnormal laboratory results indicative of, any significant cardiac, endocrinologic, hematologic, hepatic, immunologic, metabolic, urologic, pulmonary, gastrointestinal, dermatologic, psychiatric, renal, andor other major disease, that, in the opinion of the investigator, would preclude the administration of natalizumab for the duration of the study. 