HEALTH

WellPoint, Health Systems Start Mediation: The two health-care giants have met with a mediator in an effort to resolve differences that have thwarted completion of their proposed $1.7-billion merger. WellPoint Health Networks Inc. and Health Systems International Inc., both of Woodland Hills, announced plans to merge in March, but each side subsequently accused the other of breaching the agreement. Officials said WellPoint and Blue Cross attorneys met with Health Systems representatives to take steps to finalize the combination. Meanwhile, Health Systems said it completed its acquisition of a managed health-care plan and other assets from Philadelphia-based Graduate Health Systems Inc. for $94 million in cash and notes.