Part I. Overview -- Overview of the Kynurenine Pathway of Tryptophan Metabolism -- Role of Tryptophan Metabolism in Health and Disease -- Nutritional Aspects of Tryptophan Metabolism -- Role of Kynurenine Pathway in Early Brain Development -- Role of Kynurenine Pathway in Aging -- Role of Tryptophan Metabolism in Mood, Behavior, and Cognition -- Part II. Systemic Diseases -- Role of Kynurenine Pathway in Inflammatory Diseases -- Role of Kynurenine Pathway in Allergy -- Role of Kynurenine Pathway in HIV/AIDS -- Role of Kynurenine Pathway in Cardiovascular Disease -- Role of Kynurenine Pathway in Respiratory Diseases -- Role of Kynurenine Pathway in Gastrointestinal Diseases -- Role of Kynurenine Pathway in Insulin Resistance -- Role of Kynurenine Pathway in Infections -- Part III. CNS Disorders -- Role of Kynurenine Pathway in Neurodegenerative Diseases -- Role of Kynurenine Pathway in Epilepsy -- Role of Kynurenine Pathway in Stroke -- Role of Kynurenine Pathway in Pain and Migraines -- Role of Kynurenine Pathway in Autism Spectrum Disorders -- Role of Kynurenine Pathway in Neuropsychiatric Disorders -- Part IV. Oncology -- Role of Kynurenine Pathway in Stem Cell Biology -- Role of Kynurenine Pathway in Cancer Biology -- Role of Kynurenine Pathway in Neuro-oncology -- Role of the Kynurenine Pathway in Hematologic Malignancies -- Part V. Experimental Models and in Vivo Imaging -- Experimental Models to Study the Kynurenine Pathway -- Animal Models to Study the Role of Kynurenine Pathway in Mood, Behavior, and Cognition -- Applications of Small Animal PET Imaging -- Molecular Imaging of Serotonin Synthesis in the Brain -- Molecular Imaging of Tryptophan Metabolism -- Part VI. Therapeutic Approaches -- Inhibition of the Kynurenine Pathway of Tryptophan Catabolism -- Clinical Trials Targeting the Kynurenine Pathway -- The Next Decade in Tryptophan Metabolism Research.