1. Department of Physiological Sciences, University of Stellenbosch, Stellenbosch, South Africa.
2. Department of Internal Medicine II, University of Ulm, Ulm, Germany.
3. Cardiovascular Unit, Oberallgäu Kliniken GmbH, Immenstadt, Germany.
4. Department of Biochemistry, School of Biochemistry, Genetics, Microbiology, and Plant Pathology, University of KwaZulu-Natal, Pietermaritzburg, South Africa.