* Dennis E. Arnold has been named...

* Dennis E. Arnold has been named chairman of Commercial Underwriters Insurance Co. and URC Risk Managers Inc., both subsidiaries of Woodland Hills-based URC Holdings Corp. Arnold will remain vice president of another URC subsidiary, Underwriters Reinsurance Co. Previously, he worked for Transamerica Insurance Group.

Also, Judy Mann and Mark Zucco were named assistant vice presidents of Underwriters Reinsurance Co. Ann Weisskopf was promoted to assistant vice president of Commercial Underwriters.

* Bonnie L. Matheson has been named chairwoman of the Los Angeles Community Reuse Organization, a new group chartered by the U. S. Department of Energy to market to private companies the facilities of the department’s Energy Technology Engineering Center in Chatsworth.

Matheson is also president of the Valley Industry and Commerce Assn. (VICA).