In ancient Chinese thought, the concept of two complementary and opposing influences, Yin and Yang, which underpin and control all nature. The aim of Chinese medicine is to produce proper balance between them. Used in modern terms to characterize any dualistic, reciprocal control system in which one influence tends to promote things that the opposing influence tends to inhibit, and vice versa; the yin-yang hypothesis of biologic control in which cyclic GMP and cyclic AMP are supposed to act in this dualistic, reciprocal way in controlling cellular functions.
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Examples: glitazone, GI cocktail, etc.