title: Letter: Tryptophan and depression.
mesh_terms: D002986:Clinical Trials as Topic; D003863:Depression / Q000188:drug therapy*; D006801:Humans; D007099:Imipramine / Q000627:therapeutic use*; D014364:Tryptophan / Q000627:therapeutic use*
chemical_list: D014364:Tryptophan; D007099:Imipramine