I had to laugh when I was reading an article about using TPA to treat frostbite (the same medicine sometimes used for strokes and heart attacks) and there was a line that reminded me of my old mountaineering days-
"As others have previously shown, we again found that frostbite is an entity that afflicts homeless individuals and those with mental illness, and is often associated with substance abuse."

Anyway, the article was in Arch Surg. I can forward the specific reference if anybody's interested.

Mark

Try this link.
archsurg.ama-assn.org/cgi/content/full/142/6/546
If it doesn't work, let me know.
Mark