The American Medical Assn. chose the first black in its 147-year history to be the group's president-elect. Dr. Lonnie R. Bristow, an internist from San Pablo, Calif., will take on the largely speech-making role a year from now. Bristow is now chairman of the AMA board and its only black member. He said race will not define his role "because, quite simply, it has not happened once in all the years that have been leading up to today." Bristow was unopposed for president-elect at the AMA convention in Chicago.