1. Department of Surgery, Faculty of Medicine, University of Salamanca, Alfonso X El Sabio Avenue s/n, 37007 Salamanca, Spain
2. Faculty of Dentistry, University of Sevilla, Avicena Street s/n, 41009 Sevilla, Spain
3. Department of Surgery, Faculty of Medicine and Dentistry, University of Santiago de Compostela, San Francisco Street s/n, 15782 Santiago de Compostela, Spain
4. Department of Medicine, Faculty of Medicine, University of Salamanca, Alfonso X El Sabio Avenue s/n, 37007 Salamanca, Spain
5. Department of Patholoy, 12 de Octubre University Hospital, Córdoba Avenue s/n, 28041 Madrid, Spain