1. Contribution from the Department of Chemical and Screening Sciences, Wyeth Research, 500 Arcola Road, Collegeville, Pennsylvania 19426; Department of Chemical and Screening Sciences, Wyeth Research, 200 Cambridge Park Drive, Cambridge, Massachusetts 02140; Department of Chemical and Screening Sciences, Wyeth Research, Monmouth Junction, New Jersey 08852; Women's Health Research Institute, Wyeth Research, 500 Arcola Road, Collegeville, Pennsylvania 19426