1. Department of Anesthesiology, Perioperative and Pain Medicine; Stanford University, School of Medicine, Stanford, California, USA.
2. Anesthesiology Service; Veterans Affairs Palo Alto Health Care System, Palo Alto, California, USA.
3. Department of Anesthesiology, Wake Forest Baptist Medical Center, Winston-Salem, North Carolina, USA.
4. Department of Biology, University of Massachusetts Amherst, Amherst Massachusetts, USA.
5. University of California San Francisco, Brain and Spinal Injury Center, Department of Neurosurgery, San Francisco, California, USA.