The troubled Scios unit of Johnson & Johnson told employees yesterday that it would lay off 150 of its approximately 900 workers. Scios has struggled since sales of its flagship drug, the heart failure treatment Natrecor, began declining last year over safety concerns. The job cuts will affect sales and marketing staff members in the field and at the Scios home office in Fremont, Calif., according to Mark T. Wolfe, a Johnson & Johnson spokesman. He said the research and development arm would not be affected. Natrecor sales reached $400 million in 2004. But the company has said that sales declined significantly after outside medical researchers raised questions last year about whether the treatment increased the risk of kidney problems and death. Mr. Wolfe said the company would not disclose sales figures for 2005.