1. Department of Medicine, School of Medicine, University of Minnesota, 401 East River Parkway, Minneapolis, MN 55455, U.S.A.
2. Department of Immunobiology, School of Medicine, Yale University, 300 Cedar Street, New Haven, CT 06520, U.S.A.
3. Department of Pharmacology, School of Medicine, Yale University, 333 Cedar Street, New Haven, CT 06520, U.S.A.
4. Department of Neurology, School of Medicine, Yale University, 300 Cedar Street, New Haven, CT 06520, U.S.A.