1. Postdoctoral Research Fellow, Department of Anesthesiology, Baylor College of Medicine.
2. Research Assistant Professor, University of Texas Medical School at Houston.
3. Research Fellow, Department of Anesthesiology, University of Texas Medical School at Houston.
4. Professor, Department of Medicine, Baylor College of Medicine.
5. Assistant Professor, Department of Anesthesiology, University of Texas Medical School at Houston.
6. Professor, Department of Anesthesiology, University of Texas Medical School at Houston
7. Professor, Department of Anesthesiology; Director, Division of Clinical Pharmacology, Department of Pharmacology, University of Texas Medical School at Houston.