The University of California-Irvine has appointed Maureen Zehntner to head its medical center. Zehntner is a registered nurse who spent 12 years as one of the hospital's top administrators during a period in which it suffered a series of scandals. Her association with the medical program's troubled past that has led some to criticize the university for choosing Zehntner to lead the facility at a time when it is trying to wipe clean its stained reputation.