[1] UIS,NEUROL UNIT,BUCARAMANGA,COLOMBIA
[2] UNIV HOSP,BUCARAMANGA,COLOMBIA
[3] LAQMA,ENVIRONM MONITORING CHEM LAB,BOGOTA,COLOMBIA
[4] UNIV ALABAMA,SCH PUBL HLTH,INT RES LAB,BIRMINGHAM,AL 35294
[5] CHICAMOCHA CLIN,BUCARAMANGA,COLOMBIA
[6] MANUELA BELTRAN UNIV,BUCARAMANGA,COLOMBIA