For most Americans it started on Jan. 15, 1972, the night Johnny Gage and Roy DeSoto of Los Angeles County Fire Department’s Squad 51 snatched nurse Dixie McCall from the jaws of death. In saving their colleague, Johnny and Roy silenced the skeptics and cemented paramedics, still a brand-new idea at the time, a place in American folklore. That Johnny and Roy were characters on the new NBC series “Emergency!” didn’t matter. They represented something very real.