The past few years have seen an explosion in the popularity - and profitability - of complementary and alternative medicine.  Under pressure from everyone from consumers to Congress - and tempted by huge grants - major hospitals and medical schools have embraced therapies that they once dismissed as quackery.  So accepted, in fact, have alternative medical treatments become that an entire center of the National Institutes of Health is now devoted to it.  But the question remains:  Do these treatments actually work?  FRONTLINE examines the controversy over complementary and alternative medical treatments.