The Cleveland Clinic on Tuesday began sharing its expertise in developing and marketing medical inventions with a hospital system in the nation's capital. The immediate goal is to help doctors at MedStar Health --a nine-hospital system that serves Maryland and the Washington, DC, region -- turn their ideas into marketable inventions in the same way Cleveland Clinic doctors do. Longterm, Clinic and MedStar officials hope the deal leads to other kinds of collaboration, bringing together doctors, engineers and other employees from the two organizations to solve medical problems, improve treatment and advance medical education.