American Savings & Loan Assn. announced that it has completed the acquisition of five branches and deposits from two others from First Nationwide Savings . . . As expected, United Steelworkers' employees at Bethlehem Steel ratified a contract by a 3-2 margin that cuts wages and benefits by about $2 an hour but provides profit-sharing and stock plans, the union said . . . Scientific Micro Systems said it has agreed to acquire Sigen Corp., a Santa Clara, Calif., manufacturer of tape controllers and disk/tape storage systems for the IBM-PC compatible market, for undisclosed terms.