1. Repligen Corporation, Cambridge, MA 02139.
2. Merck Sharp & Dohme Research Laboratories, West Point, PA 19486.
3. Department of Surgery, Duke University Medical School, Durham, NC 27710.
4. BioTech Resources, Inc., San Antonio, TX 98249.
5. Department of Medicine, Wilford Hall, U.S. Air Force Medical Center, Lackland Air Force Base, TX 78236.
6. Department of Chemistry, Harvard University, Cambridge, MA 02138.