After 90 years of paying all the bills at its children's hospitals, Shriners is asking a new group for help: insurance companies. The Tampa-based charity began billing insurance carriers and government-backed plans almost a year ago after a lousy economy and escalating health-care expenses sapped its endowment. The choice was inevitable, said William Aaronson, an associate professor of health care management at Temple's Fox School of Business. "If you can't make a profit, you can't fulfill your mission," he said.