URBANA, ILLINOIS Millions of people take herbal remedies for conditions ranging from mild problems such as the common cold to severe disorders, such as Alzheimer's disease. But even when these types of medicines have proved effective in clinical trials, it often remains unclear as to how they work in the body. Researchers typically test a hypothesis that is essentially an educated guess as to how, for example, a herbal medicine such as Echinacea might potentially boost the immune system. But, a new approach could help speed such research by removing a lot of the guesswork.