Bill,
Most professions will require some additional study, exams or licensing.
For engineers, solid experience is almost a requirement while some engineering jobs will require US citizenship or at least graduation from an ABET accredited engineering school.
Nurses are usually in demand here even in tight employment markets but engineers, teachers, and doctors generally are not.
I know a lot of Philippine licensed dentists working here as dental assistants. Many Filipino MDs are going back to school for a nursing degree so they can possibly emigrate overseas and make much more as a RN than they can as a doctor in the PI.
Ray