I am looking through the demo but can't find what I am looking for but very possible I'm just missing it. Can I restrict a backend user to a specific publication and a specific Topic/Section?
One solution would be to create a User Type with permissions so that these users' articles can only go into the Pending queue (which has a widget on the Dashboard). It would then be up to the editor to move the articles to the appropriate publication, issue and section. See: