1. Head Injury Center, Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania
2. Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania
3. The R.W. Johnson Pharmaceutical Research Institute, Spring House, Pennsylvania
4. Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah
5. Head Injury Center, Department of Neurosurgery, University of Pennsylvania, and the Veterans Administration Medical Center, Philadelphia, Pennsylvania