A potential medical error at the University of Chicago Medical Center claimed the life of one of its own trustees, reports the Chicago Tribune. James Tyree died as the result of an air embolism created by the removal of a dialysis catheter, according to the Cook County Medical Examiner. Tyree, 53, was the CEO and chairman of Mesirow Financial, and also controlled several area newspapers, including the Chicago Sun-Times. He sat on the University of Chicago Medical Center's board. Tyree had been undergoing treatment for stomach cancer since last fall, but was hospitalized for pneumonia. The medical examiner's report noted that Tyree's pneumonia and cancer were secondary causes of death. Article