1. U.S. Food and Drug Administration, 200 C Street, SW, Washington, DC 20204
2. Anesthesia Research Laboratories, Harvard Medical School, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115
3. Yale University, School of Medicine, 333 Cedar Street, New Haven, CT 06510
4. Current address: Department of Neuroscience, Johns Hopkins University School of Medicine, 725 Wolfe Street, Baltimore, MD 21205
5. Department of Chemistry, University of Alaska, Fairbanks, AK 99701