Publicis Healthcare’s parent is buying Medical Broadcasting Company owner Digitas, Inc. for $1.3 billion. Publicis cited projections that digital and interactive spending will account for 10% of global communications investments by 2010 as its rationale for the acquisition. Boston-based Digitas, Inc. includes its namesake direct mail and interactive business, Philadelphia healthcare interactive firm Medical Broadcasting Company and Norwalk, CT-based interactive agency Modem Media.In addition to Publicis Healthcare Communications Group, which includes Medicus, Saatchi & Saatchi Healthcare, LifeBrands, BrandPharm and Williams-Labadie, Paris-based Publicis holdings include MS&L, Leo Burnett, BBH, Fallon, Starcom Mediavest and Zenith Optimedia.