1. College of Pharmacy, Oregon State University, Corvallis, Oregon 97331, Southwest Foundation for Biomedical Research, San Antonio, Texas 78227, Chemical and Screening Sciences, Wyeth Research, Cambridge, Massachusetts 02140, Instituto de Investigaciones Científicas Avanzados y Sevicios de Alta Tecnología, Clayton, Panama 5, Republic of Panama, Scripps Institution of Oceanography and Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California 92093