BIOMEDICINE

Stake Increased: Ropak Corp. said it has increased its 20% stake to a 33% interest in Ropak Laboratories, formally known as National Testing Corp. The Fullerton company paid $500,000 in cash for the 13% stake it acquired last week.

Ropak Labs in Irvine makes test kits used to determine if certain pharmaceuticals, cosmetics and household chemicals will irritate eye tissue. The test kit is sold as an option to the use of live rabbits in such tests.