1. Dept. of Surg., Karolinska Hosp., Stockholm, Sweden.; Dept. of Clin. Chem., Central Hosp. in Rogaland, Stavanger, Norway; Dept. of Clin. Biol., Div. of Pharmacol., Univ. of Bergen, Haukeland Hosp., Bergen, Norway; Dept. of Epidemiol., Inst. of Environ. Med., Karolinska Inst., and Div. of Cardiovasc. Med., Dept. of Med., Karolinska Hosp., Stockholm, Sweden