1. The Bristol-Myers Squibb Pharmaceutical Research Institute, Process Research and Development, P.O. Box 4000, Princeton, New Jersey 08543, U.S.A., Process Research and Development, P.O. Box 191, New Brunswick, New Jersey 08903, U.S.A. and Biopharmaceutics Research and Development, P.O. Box 191, New Brunswick, New Jersey 08903, U.S.A.