Karen Pletz, president and chief executive officer of the Kansas City University of Medicine and Biosciences, was fired Friday afternoon. The school offered no explanation, according to spokeswoman Laurie Roberts. “Due to the fact that this is a personnel matter, no further comment about her termination will be issued,” Roberts said. “She is no longer an employee here.” Pletz did not return phone calls to her home early Friday evening. Danny Weaver, chairman of the board of trustees, is the school’s acting president. Weaver is taking a leave of absence from his private practice in Florida to step in temporarily as president.