1. Department of Anesthesiology, Loma Linda University Medical Center, Loma Linda, CA 92354, USA
2. Department of Physiology and Pharmacology, Loma Linda University School of Medicine, 11041 Campus Street, Risley Hall, Room 219, Loma Linda, CA 92354, USA
3. Department of Neurosurgery, University Hospital Innsbruck, 6020 Tyrol, Austria
4. Department of Neurosurgery, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA