From the Department of Veterans Affairs Medical Center (C.H.C., W.W.B., J.A.H., K.G.R., O.H.L.B.), Boston, Mass; Department of Medicine (C.H.C., W.W.B., O.H.L.B.), Tufts University School of Medicine, Boston, Mass; Department of Pathology (J.A.H.), Boston University School of Medicine, Boston, Mass; and Research Division (S.S.), Cleveland Clinic Foundation, Cleveland, Ohio. (At 1995-01)