1. Roche Central America & Caribbean, Heredia, Costa Rica;
2. Department of Nephrology, Hospital Santo Tomás, Panama, Panama;
3. Caja de Seguro Social, Complejo Hospitalario Dr. Arnulfo Arias Madrid, Panama, Panama;
4. Department of Pharmacology School of Medicine, University of Costa Rica, San José, Costa Rica;
5. United BioSource Corporation, Montreal, Canada