1. Department of Neurosurgery, Loma Linda University, Loma Linda, California, USA.
2. Department of Physiology and Pharmacology, Loma Linda University, Loma Linda, California, USA.
3. Occupational Medicine, Southern California Kaiser Permanente, Riverside, California, USA.
4. Department of Preventive Medicine, Loma Linda University, Loma Linda, California, USA.
5. Department of Anesthesiology, Loma Linda University, Loma Linda, California, USA.