1. Institute of Clinical Chemistry, University Hospital Zurich, CH-8091 Zurich, Switzerland
2. Competence Center for Systems Physiology and Metabolic Diseases, ETH Zurich and University of Zurich, CH-8093 Zurich, Switzerland
3. Department of Experimental Vascular Medicine, Academic Medical Center, 1105 AZ Amsterdam, The Netherlands
4. Department of Clinical Biochemistry, Rigshospitalet, Copenhagen University Hospital, 2100 Copenhagen, Denmark
5. Center for Integrative Human Physiology, University of Zurich, CH-8093 Zurich, Switzerland