K C S Fong C G Ferrett R Tandon B Paul J Herold C S C Liu

norman ramirez mayaguez medical center, mayaguez, hospital de la concepcion, san german, puerto rico; school of medicine, ponce health sciences university, ponce, puerto rico; mayaguez medical center, mayaguez, hospital de la concepcion, san german, p. o. box: 6847, mayaguez, puerto rico. tel: +1-7872642066 sigfredo villarin school of medicine, ponce health sciences university, ponce, puerto rico robert ritchie ponce research institute, ponce, puerto rico kenira j. thompson department of physiology, neuroscience division, ponce health sciences university, ponce research institute, ponce, puerto rico