Most studies of the question have been small trials sponsored by pharmaceutical companies and have failed to show that the drugs are effective for depressed teenagers.

One trial, sponsored by Boston Scientific, randomly assigns 1,500 patients to either surgery or stenting.

There are currently several active clinical trials sponsored and administered by the developer of antineoplastons.

Currently about 25,000 patients a year enter the large clinical trials sponsored by the National Cancer Institute in which many institutions take part.

It offers a computerized listing of trials sponsored by the institute.

The trial, sponsored by Pfizer, the drug's manufacturer, involved 63 patients whose tumors had continued to worsen despite previous treatment with interleukin-2 or interferon.

The clinical trial, sponsored by the cancer institute, is still under way but the results were announced early because the trial had already met its main goal.

Another trial sponsored by a different company, Neuropace, is testing a different stimulator.

Dr. Posner said that she had participated in some trials sponsored by drug makers but never as a principal investigator.

These trials, sponsored by NCI, were done in the late 1970s and early 1980s, and did not include a control group for comparison.