The Los Angeles Business Journal’s index of largest local public companies closed down for the week, following a volatile week in the larger markets.

The weighted LABJ Stock Index fell 1.6 percent to 158.66 for the trading week ended June 21. Decliners outpaced gainers 108 to 49, with eight companies unchanged.

OSI Systems Inc. rose 12 percent to $63.51. The Hawthorne technology company learned that the U.S. government won’t bar OSI’s Rapiscan unit from selling its controversial full-body scanners to government agencies. (They have been removed from U.S. airports.)

Also among the biggest gainers was Motorcar Parts of America Inc. which rose another 30 percent to $9.52, after gaining 22 percent the previous week. The Torrance auto parts company took a $84.7 million charge in its fiscal fourth quarter after writing off the failed acquisition of a Canadian auto parts maker.

Puma Biotechnology Inc. rose 16 percent to $42.55. The Westwood cancer drug developer continued to benefit from anticipated success for its experimental breast cancer treatment.

Staar Surgical Co. gained 14 percent to $10.24. The Monrovia maker of implantable eye lenses said it had received regulatory approval to sell one of its products in Korea and Argentina.

The biggest decliner was Ceres Inc., which was last week’s biggest gainer. The Thousand Oaks developer of genetically modified seeds for biofuel crops saw some profit-taking on shares, falling 27 percent to $3.09, after soaring 82 percent last week on positive analyst’s report.

Tetra Tech Inc. fell 11 percent to $23.74. The Pasadena engineering services firm projected a fiscal third quarter loss of 30 cents to 50 cents a share due to problems with contracts in the United States and Canada and falling demand for its mining services in Canada.