1. Division of Neurosurgery, Loyola University Medical Center, Chicago, Illinois
2. University of Illinois College of Medicine, and Department of Neurosurgery, Loyola University Medical Center, Chicago, Illinois
3. Cook County Hospital and Hektoen Institute for Medical Research, Department of Anatomy and Cell Biology, Loyola University Medical Center, Chicago, Illinois
4. Department of Microbiology and Immunology, Loyola University Medical Center, Chicago, Illinois