1. Department of Veterinary Medical Chemistry, Swedish University of Agricultural Sciences, Uppsala Biomedical Center, Box 575, S-751 23 Uppsala, Sweden, Department of Microbiology and Immunology and Sol Sherry Thrombosis Research Center, Temple University Medical School, 3400 North Broad Street, Philadelphia, Pennsylvania 19140, and Center for Molecular Biology of Oral Diseases, University of Illinois at Chicago, 801 South Paulina Street, Chicago, Illinois 60612