1. Institute of Pharmacology, University of Bern, CH-3010 Bern, Switzerland;
2. Department of Internal Medicine I, Division of Hematology and Hemostaseology, Medical University of Vienna, A-1090 Vienna, Austria
3. Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892
4. Department of Medicine, National Jewish Health, Denver, Colorado 80206