1. Department of Medical Biochemistry and MicrobiologyUppsala University BMC, Box 582 SE-751 23 Uppsala Sweden
2. Department of PhysiologyUniversity of Bergen N-5009 Bergen Norway
3. Department of RadiologyUniversity Hospital SE-751 85 Uppsala Sweden
4. Department of Medical Cell Biology, Section of PhysiologyUppsala University BMC, Box 571 SE-751 23 Uppsala Sweden