As it continues to scale up its $3 billion media agency operation, MDC Partners has appointed agency veteran Dene Callas to the new role of managing director of Maxxcom Global Media, the Toronto-based holding company’s media oversight unit. Callas is the No. 2 executive at Maxxcom reporting to CEO Steve Farella. In her new role, Callas is responsible for building the group’s offering and resources. She will work with MDC agencies, including TargetCast, Media Kitchen and RJ Palmer as well as full-service shops like Crispin Porter + Bogusky, as they integrate the growing array of holding company media assets into their individual agency offerings.