Asher B. Edelman said his investment group...

Asher B. Edelman said his investment group has bought more shares of Centel Corp., the Chicago-based telecommunications concern, and is seeking buyers for parts of the company. Centel, meanwhile, announced that it will notify the American Stock Exchange of what it considers to have been unusual trading activity in its options contracts Tuesday, the day Edelman’s group conditionally offered to buy Centel in a $2.8-billion bid. Edelman did not say how many shares he purchased.