1. The Glycosciences Laboratory, Imperial College School of Medicine, Northwick Park Hospital, Watford Road, Harrow, Middlesex HA1 3UJ, U.K., Department of Applied Bioorganic Chemistry, Gifu University, Gifu, 501-11, Japan, Laboratory de Chimie Organique Multifunctionelle, Université de Paris Sud, Orsay Cedex 91405, France, and Genetics Institute, Inc., Cambridge, Massachusetts 01240