1. Medicinal Chemistry Section, National Institute on Drug Abuse-Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, Maryland 21224
2. Psychobiology Section, National Institute on Drug Abuse-Intramural Research Program, National Institutes of Health, 251 Bayview Boulevard, Baltimore, Maryland 21224
3. Center for Molecular Recognition and Departments of Psychiatry and Pharmacology, Columbia University College of Physicians and Surgeons, New York, New York 10032