First Interstate Bancorp's takeover of troubled Allied Bancshares Inc. of Houston was approved by the Federal Reserve Board. The firms said they hoped to close the deal by year-end. In approving the transaction, the Fed turned aside objections by minorities that the two firms didn't do enough to make loans available for low-income housing. Allied is the sixth-largest bank holding company in Texas and the 53rd largest in the nation. Los Angeles-based First Interstate agreed in May to buy Allied in a stock swap valued at between $415 million and $450 million.