The top financial officer of American Airlines says it is impossible to tell how many of the employee layoffs announced last week will be premanent. Jeff Campbell says the airline is doing everything it can to save money. Campbell adds the airline hasn’t determine how its cost-saving moves will affect St. Louis. He says the undertaking is so large, the company hasn’t had time to consider what to do with the operations it acquired when it absorbed Trans World Airlines and took over the TWA hub at Lambert St. Louis International Airport.