1. Division of Clinical Chemistry, Central Hospital in Rogaland, 4003 Stavanger, Norway
2. Department of Surgery, St. Görans Hospital, Stockholm 17176, Sweden
3. Department of Chemistry, University of Hull, Hull HU6 7RX, United Kingdom
4. Department of Public Health, University of Glasgow, Glasgow G12 8QQ, United Kingdom
5. Departments of Clinical Biochemistry and
6. Pharmacology, University of Bergen, Bergen N-5021, Norway