The American and Toronto stock exchanges began two-way, international electronic trading in equity securities . . . Monoclonal Antibodies said it signed agreements with Ortho Pharmaceutical to develop and supply home diagnostic medical tests incorporating Monoclonal's technology for Ortho . . . The American Iron and Steel Institute reported that steel production for the week ended Sept. 21 totaled 1.594 million tons, an increase of 0.8% from the previous week.