1. Universidad Central del Ecuador, Ciencias Médicas, Carrera de Medicina, Hospital de Especialidades de Fuerzas Armadas HE-1, Quito, Ecuador
2. Department of Surgery and Anatomy, Ribeirao Preto Medical School, University of São Paulo, São Paulo, Brazil
3. Department of Social Medicine, Ribeirao Preto Medical School, University of São Paulo, São Paulo, Brazil
4. Department of Pathology, Ribeirao Preto Medical School, University of São Paulo, São Paulo, Brazil
5. Department of Internal Medicine, Ribeirao Preto Medical School, University of São Paulo, São Paulo, Brazil