1. Department of Biophysical Chemistry, Lund University, Chemical Center, S-221 00 Lund, Sweden, Department of Laboratory Medicine, Division of Medical Microbiology, Lund University, Sölvegatan 23, S-223 62 Lund, Sweden, and Department of Laboratory Medicine, Division of Clinical Chemistry, Lund University, University Hospital Malmö, S-205 02 Malmö, Sweden