1. From Brigham Young University (C.A.P.), Provo Utah; Health Canada (R.T.B.) and University of Ottawa (R.T.B., D.K.), Ottawa, Canada; New York University School of Medicine (G.D.T.), Tuxedo, NY; American Cancer Society (M.J.T., E.E.C.), Atlanta, Ga; and Department of Pathology (J.J.G.), Harvard Medical School, Boston, Mass.