1. Guest Researcher, Laboratory of Chemical Pharmacology, National Institutes of Health.
2. Research Associate, Laboratory of Chemical Pharmacology, National Institutes of Health.
3. Instructor, Department of Anesthesiology, Georgetown University, School of Medicine.
4. Visiting Associate, Laboratory of Chemical Pharmacology, National Institutes of Health.
5. Chief, Section on Pharmacological Chemistry, Laboratory of Chemical Pharmacology, National Institutes of Health.