the original US studies failed, despite some decent success in europe. the newer clinical trials seem to be based in boston, but there's also a clinical trial being run out of the university of miami. i didn't find too much on the internet yesterday, and i really don't have time to look... unfortunately.
you MIGHT have some luck searching
www.clinicaltrials.com or
www.clinicaltrials.gov or
www.centerwatch.com
or the FDA's medical device division...
www.FDA.gov
i'll look when i get more time, but it probably won't be until at least next week.
good luck!!!!