1. Sterling Rock Falls Clinic, Sterling, IL, USA
2. University of Illinois College of Medicine, Peoria, IL, USA
3. Department of Pharmacological Sciences, University of Milan & IRCSS Multimedica, Milan, Italy
4. Merck, 351 N Sumneytown Pike, PO Box 1000, UG3D-08, North Wales, PA 19454-2505, USA