Highmark Inc. expects to control 75 percent of Jefferson Regional Medical Center's board of directors by the end of the year, officials said on Tuesday. The two nonprofits announced a "strategic partnership" in which the state's largest insurer will assume $200 million of the Jefferson Hills hospital's debts and obligations, pay $75 million into Jefferson Regional's community foundation and upgrade its emergency department and clinical services. Officials declined to speculate about the cost of the upgrades. "This is not a rescue," Highmark Chairman J. Robert Baum said. "This is instead part of a growth strategy we both have."