1. Department of Pathology, University of Pittsburgh, Scaife Hall S-737, 3550 Terrace Street Pittsburgh, Pennsylvania 15261, Collaborations in Chemistry, Inc., Jenkintown, Pennsylvania 19046, Department of Pharmacology, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway, 675 Hoes Lane, New Jersey 08854, and Department of Pharmaceutical Sciences, University of Maryland, 20 Penn Street, Baltimore, Maryland 21201