1. Tsukuba Research Institute in collaboration with Merck Research Laboratories, Banyu Pharmaceutical Co., Ltd. (A.K., S.M., N.M., N.S., J.I., T.Fuku, T.Fuka., Y.S., S.N., M.I.), Okubo 3, Tsukuba 300-2611, Japan
2. Merck Research Laboratories, Merck & Co., Inc. (N.M., D.J.M., L.H.T.V.d.P.), Rahway, New Jersey 07065