U.S. Treasury prices fell Wednesday after weak demand for a debt sale dampened gains built on Federal Reserve Chairman Ben Bernanke's assurances U.S. interest rates will remain low. In a day of choppy trade, the lackluster reception for $35 billion in five-year notes overshadowed weaker than forecast durable goods orders that earlier lifted bond prices from session lows. Another influence was the Fed's purchase of $4.81 billion of Treasuries