1. Department of Medicine, New England Medical Center Hospitals, Boston, MA 02111.
2. Department of Neurosurgery, New England Medical Center Hospitals, Boston, MA 021 11.
3. Department of Pathology, New England Medical Center Hospitals, Boston, MA 02111.
4. Department of Medicine, Division of Endocrinology, Brown University, Rhode Island Hospital, Providence, RI 02902.