Maryland and Prince George's County announced a partnership Thursday with the University of Maryland Medical System to attempt to stabilize the county's debt-addled and understaffed hospital system. The partnership would unite the parties in a $600 million effort to improve quality and access to healthcare across Prince George's and build a new regional medical center in the county within the next four years. Officials are optimistic the agreement will help improve health care in a county that has struggled with high mortality rates, a shortage of primary care physicians and a high number of uninsured residents. The county's three primary medical facilities - Bowie Health Center, Laurel Regional Hospital and Prince George's Hospital Center in Cheverly - are run by nonprofit Dimensions Healthcare System. All three have been saddled with debt for years, and Prince George's Hospital Center narrowly avoided shutdowns in 2006 and 2007 due to its financial woes.