Gout and uric acid lithiasis are known to have affected mankind for thousands of years. It is only recently, however, that great progress has been made in the understanding of the processes involved in purine metabolism and its disorders in man. The key enzymes active in the various pathways of purine synthesis and degradation have become known and their properties are the subject of intensive study. Major contributions to the knowledge of normal purine metabolism in man have derived from the study of inborn errors in patients with purine disorders, specifically complete and partial hypoxanthine-guanine phosphoribosyltransferase deficiency. Mutations of other enzymes involved in purine metabolism are being discovered. A great step forward has been made in the treatment of gout with the introduction of uricosuric drugs and more recently of the hypoxanthine analogue allopurinol, a synthetic xanthine oxidase inhibitor. Furthermore, the complex nature of the renal handling of uric acid excretion, although still posing difficult problems, appears to approach clari fication.

Inhalt
of Volume 41A.- Enzymes and Metabolic Pathways in Purine Metabolism.- Purine Phosphoribosyltransferases.- Human Hypoxanthine-Guanine Phosphoribosyltransferase (HGPRT): Purification and Properties.- Stabilization by PRPP of Cellular Purine Phosphoribosyltransferases Against Inactivation by Freezing and Thawing. Study of Normal and HypoxanthineGuanine Phosphoribosyltransferase Deficient Human Fibroblasts.- Purification and Characterization of a Neural Hypoxanthine-GuaninePhosphoribosyltransferase (HGPRT).- Human Adenine Phosphoribosyltransferase: Purification, Subunit Structure and Substrate Specificity.- Genetic Control of Bacterial Purine Phosphoribosyltransferases and an Approach to Gene Enrichment.- Glutamine-PRPP Amidotransferase.- Human Glutamine Phosphoribosylpyrophosphate (PP-ribose-P) Amidotransferase: Kinetic, Regulation and Configurational Changes.- Xanthine Oxidase.- Xanthine Oxidase and Aldehyde Oxidase in Purine and Purine Analogue Metabolism.- Regulation of Xanthine Dehydrogenase and Purine Nucleoside Phosphorylase Levels in Chick Liver.- Xanthine Oxidase Activity of Mammalian Cells.- PRPP Synthetase and PRPP.- Human Phosphoribosylpyrophosphate (PP-Ribose-P) Synthetase: Properties and Regulation.- Regulatory Aspects of the Synthesis of 5-Phosphoribosyl-l-pyrophosphate in Human Red Blood Cells.- Pharmacological Alterations of Intracellular Phosphoribosylpyrophosphate (PP-Ribose-P) in Human Tissues.- Nucleoside and Nucleotide Metabolism.- Purine Salvage in Spleen Cells.- Purine Nucleotide Synthesis, Interconversion and Catabolism in Human Leukocytes.- Incorporation of Purine Analogs into the Nucleotide Pools of Human Erythrocytes.- A Role of Liver Adenosine in the Renewal of the Adenine Nucleotides of Human and Rabbit Erythrocytes.- Purine Nucleoside Metabolism in Escherichia coli.- Synthesis of Purine Nucleotides in Human and Leukemic Cells. Interaction of 6-Mercaptopurine and Allopurinol.- Enzymes of Purine Metabolism in Platelets: Phosphoribosylpyrophosphate Synthetase and Purine Phosphoribosyltransferases.- Mutations Affecting Purine Metabolism.- Properties of HGPRT and APRT in HGPRT Deficient Blood Cells.- Hypoxanthine-Guanine Phosphoribosyltransferase Deficiency: Altered Kinetic Properties of a Specific Mutant Form of the Enzyme.- Hypoxanthine-Guanine Phosphoribosyltransferase (HGPRT) Deficiency: Immunologic Studies on the Mutant Enzyme.- Immunological Studies of Hypoxanthine-Guanine Phosphoribosyltransferase in Lesch-Nyhan Syndrome.- Unstable HPRTase in Subjects with Abnormal Urinary Oxypurine Excretion.- Hypoxanthine-Guanine Phosphoribosyltransferase (HGPRT) Deficiency: Effect of Dietary Purines on Enzyme Activity.- Properties of Erythrocyte Purine Phosphoribosyltransferases in Partial Hypoxanthine-Guanine Phosphoribosyltransferase Deficiency.- Resistance of Erythrocyte Adenine Phosphoribosyltransferase in the Lesch-Nyhan Syndrome to Destabilization to Heat by Hypoxanthine.- Purine Metabolism in HGPRT Deficient Cells.- Purine Metabolism in Intact Erythrocytes from Controls and HGPRT Deficient Individuals.- Incorporation of 3H-Hypoxanthine in PHA Stimulated HGPRT Deficient Lymphocytes.- Studies on Metabolic Cooperation Using Different Types of Normal and Hypoxanthine-Guanine Phosphoribosyltransferase (HG-PRT) Deficient Cells.- Regulation of de novo Purine Synthesis in the Lesch-Nyhan Syndrome.- Biochemical Characteristics of 8-Azaguanine Resistant Human Lymphoblast Mutants Selected in Vitro.- Clinical Manifestations and Genetic Aspects.- Hypoxanthine-Guanine Phosphoribosyltransferase Deficiency. Our Experience.- Hypoxanthine-Guanine Phosphoribosyltransf erase and Deutan Colour Blindness: The Relative Positions of This Loci on the x-Chromosome.- Purine Metabolism and Erythrocyte PRPP Content in Heterozygotes for HGPRT Deficiency.- Urate Metabolism in Heterozygotes for HGPRTase Deficiency.- Erythrocyte PRPP Concentrations in Heterozygotes for HGPRTase Deficiency.- Mutants of PRPP Synthetase.- Mutant Phosphoribosylpyrophosphate Synthetase in Two Gouty Siblings with Excessive Purine Production.- Increased PP-Ribose-P Synthetase Activity: A Genetic Abnormality Leading to Excessive Purine Production and Gout.- APRT Deficiency.- Adenine Phosphoribosyltransferase Deficiency: Report of a Second Family.- Adenine Phosphoribosyltransferase Deficiency in a Female with Gout.- Gout with Adenine Phosphoribosyltransferase Deficiency.- Xanthinuria.- Xanthinuria in a Large Kindred.- Glycogen Storage Disease.- An Unusual Case of Glycogen Storage Disease.- Hyperuricemia and Dicarboxylicaciduria in Glycogen Storage Disease.