��:�����:�: ���f;��'::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: THE PIG AS MODEL . Maternal and Fetal Nutrition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Infant Nutrition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Carbohydrate and Lipid Metabolism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Amino Acid Metabolism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vitamin and Mineral Nutrition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CONCLUSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

The pig as a model for human nutrition

The authors were asked by the Editors of ACS Chemical Biology to write an article titled “Why Nature Chose Selenium” for the occasion of the upcoming bicentennial of the discovery of selenium by the Swedish chemist Jons Jacob Berzelius in 1817 and styled after the famous work of Frank Westheimer on the biological chemistry of phosphate [Westheimer, F. H. (1987) Why Nature Chose Phosphates, Science 235, 1173–1178]. This work gives a history of the important discoveries of the biological processes that selenium participates in, and a point-by-point comparison of the chemistry of selenium with the atom it replaces in biology, sulfur. This analysis shows that redox chemistry is the largest chemical difference between the two chalcogens. This difference is very large for both one-electron and two-electron redox reactions. Much of this difference is due to the inability of selenium to form π bonds of all types. The outer valence electrons of selenium are also more loosely held than those of sulfur. As a result,...

Why Nature Chose Selenium

Selenium in the environment

1. Forms of Selenium.- 1.1 Low Molecular-Weight Compounds.- 1.1.1 Selenocysteine.- 1.1.2 Selenocystine.- 1.1.3 Selenohomocystine.- 1.1.4 Se-methylselenocysteine.- 1.1.5 Selenocystathionine.- 1.1.6 Selenomethionine.- 1.1.7 Se-methylselenomethionine.- 1.1.8 Dimethyl Selenide.- 1.1.9 Dimethyl Diselenide.- 1.1.10 Trimethyl Selenonium.- 1.1.11 Elemental Selenium.- 1.1.12 Selenotaurine.- 1.1.13 Selenocoenzyme A.- 1.1.14 Other Compounds.- 1.2 Macromolecular Forms of Selenium.- 1.2.1 Formate Dehydrogenase.- 1.2.2 Glycine Reductase.- 1.2.3 Nicotinic Acid Hydroxylase.- 1.2.4 Xanthine Hydrogenase.- 1.2.5 Thiolase.- 1.2.6 Glutathione Peroxidase.- 1.2.7 Miscellaneous Selenoproteins.- 1.2.8 Seleno-tRNA's.- 11.11 References.- 2. Selenium Deficiency Diseases in Animals.- 2.1 Introduction.- 2.2 Dietary Liver Necrosis and Factor 3.- 2.2.1 Discovery.- 2.2.2 Pathology.- 2.2.3 Biochemical Defect.- 2.2.4 Hepatosis Dietetica.- 2.3 Nutritional Muscular Dystrophy.- 2.3.1 Pathology.- 2.3.2 Prevention of NMD.- 2.4 Exudative Diathesis.- 2.5 Pancreatic Degeneration.- 2.6 Mulberry Heart Disease.- 2.7 Reproductive Problems.- 2.8 Myopathy of the Gizzard.- 2.9 Growth.- 2.10 Selenium-Responsive Unthriftiness of Sheep and Cattle.- 2.11 Periodontal Disease of Ewes.- 2.12 Encephalomalacia.- 11.11 References.- 3. Metabolism of Selenium.- 3.1 Absorption.- 3.2 Placental Transfer.- 3.3 Mechanism of the Antioxidant Action of Selenium.- 3.4 Effect of Paraquat.- 3.5 Effect on Cytochrome P-450.- 3.6 Selenium and Hepatic Heme Metabolism.- 11.11 References.- 4. Comparative Metabolism and Biochemistry of Selenium and Sulphur.- 4.1 Introduction.- 4.2 Comparative Metabolism of Selenium and Sulphur.- 4.2.1 Microorganisms.- 4.2.2 Plants.- 4.2.3 Animals.- 4.3 Comparative Biochemistry of Selenium and Sulphur.- 4.3.1 Selenopersulfide as an Electron Transfer Catalyst.- 4.3.2 Iron-Sulphur Proteins.- 4.3.3 Sulphur Salts and Selenium Toxicity in Animals.- 4.3.4 Other Selenium-Sulphur Interactions.- 11.11 References.- 5. Biological Interactions of Selenium with Other Substances.- 5.1 Cadmium.- 5.1.1 Pathological Effects.- 5.1.2 Cadmium-Zinc Interactions.- 5.1.3 Cadmium-Selenium Interactions.- 5.1.4 Effect on Drug Response.- 5.2 Arsenic.- 5.3 Copper.- 5.4 Silver.- 5.5 Cobalt.- 5.6 Manganese.- 5.7 Lead.- 5.8 Mercury.- 5.8.1 Inorganic and Organic Mercury.- 5.8.2 Tissue Distribution.- 5.8.3 Properties of the Mercury-Selenium Complex.- 5.8.4 Teratogenicity.- 5.9 Thallium.- 5.10 Tellurium.- 5.11 Vanadium.- 5.12 Bismuth.- 5.13 Other Substances.- 11.11 References.- 6. Environmental Occurrence of Selenium.- 6.1 Geochemistry of Selenium.- 6.2 Soil Selenium.- 6.3 Uptake and Concentration of Trace Elements in the Roots, Stems, and Leaves of Plants.- 6.4 Forage Selenium.- 6.5 Selenium in Water.- 6.6 Selenium in Food.- 6.7 Intakes and Recommended Daily Allowance in Humans.- 6.8 Regulations in Regard to Animal Diets.- 11.11 References.- 7. Toxicity of Selenium.- 7.1 Introduction.- 7.1.1 Acute Toxicity.- 7.1.2 Blind Staggers.- 7.1.3 Alkalai Disease.- 7.1.4 Toxicity in Rabbits.- 7.1.5 Toxicity in Hamsters.- 7.1.6 Toxicity in Sheep.- 7.1.7 Toxicity in Rats.- 7.1.8 Effect of Diet on Toxicity.- 7.1.9 Biochemical Lesions.- 7.1.10 LD50 of Various Selenium Compounds.- 7.2 Industrial Medical Aspects.- 7.2.1 Occupational Hazards.- 7.2.2 Permissible Limits for Selenium Exposure.- 7.2.3 Toxicity in Humans.- 11.11 References.- 8. Selenium in Health and Disease.- 8.1 Selenium and Cancer.- 8.1.1 Skin Cancer.- 8.1.2 Liver Cancer.- 8.1.3 Colon Cancer.- 8.1.4 Breast Cancer.- 8.1.5 Tracheal Cancer.- 8.1.6 Chemotherapeutic Effect of Selenium.- 8.1.7 Epidemiological Relationship.- 8.1.8 Selenium Blood Levels in Cancer Patients.- 8.1.9 Selenium as a Carcinogen.- 8.2 Selenium and Mutagenesis.- 8.2.1 Antimutagenicity.- 8.2.2 Mutagenicity.- 8.3 Selenium and Immunity.- 8.3.1 Effect of Selenium on Humoral Immunity.- 8.3.2 Cell-Mediated Immunity.- 8.3.3 Nonspecific Immune Effects of Selenium.- 8.4 Selenium and Dental Caries.- 8.5 The Anti-Inflammatory Properties of Selenium.- 8.6 Selenium and Heart Disease.- 8.6.1 Animals.- 8.6.2 Humans.- 8.7 Selenium and Aging.- 8.8 Cystic Fibrosis.- 8.9 Multiple Sclerosis.- 8.10 Cataracts.- 8.11 Other Diseases.- 8.12 Radioselenium as a Diagnostic Agent.- 11.11 References.- 9. Synthetic Forms of Selenium and Their Chemotherapeutic Uses.- 9.1 Anti-Infective Agents.- 9.1.1 Antibacterial.- 9.1.2 Antiviral.- 9.2 Antifungal Agents.- 9.3 Antiparasitic Agents.- 9.4 Compounds Affecting the Central Nervous System.- 9.4.1 Hypnotics.- 9.4.2 Analgesics and Local Anesthetics.- 9.4.3 Tranquilizing Drugs.- 9.5 Compounds that Affect the Autonomic Nervous System.- 9.6 Compounds that Affect the Circulatory System.- 9.7 Anti-Inflammatory Compounds.- 9.8 Antihistamines.- 9.9 Anticancer Agents.- 9.10 Antiradiation Agents.- 9.11 Steroids.- 9.12 Selenocoenzyme A.- 9.13 Selenium-Containing Carbohydrates.- 9.14 Seleno-Amino Acids.- 11.11 References.- 10. Analytical Methods of Selenium Determination.- 10.1 Introduction.- 10.2 Sample Preparation and Storage.- 10.3 Destructive Analysis.- 10.3.1 Ashing.- 10.3.2 Closed-System Combustion.- 10.3.3 Wet Digestion.- 10.3.4 Measurement of Selenium.- 10.4 Nondestructive Analysis.- 10.4.1 Neutron Activation Analysis.- 10.4.2 X-Ray Fluorescence Analysis.- 10.4.3 Proton-Induced X-Ray Emission.- References.

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Biochemistry of selenium.

Publisher Summary This chapter reviews the geomedical aspects of selenium (Se), ranging from the soil through the plants to animal and human nutrition. Selenium has several essential functions in the animal and human body, and interactions occur with other elements and compounds. The beneficial effects of Se are obtained at different concentration levels, depending on the functions of Se and on interacting factors such as vitamin E, fatty acids, and sulfur. The nutritional minimum level for animals and humans is about 0.05–0.10 ppm Se in dry fodder/food, and intake below that cause severe deficiency diseases. At somewhat higher levels of Se intake, there are indications of a protective effect toward a number of human diseases, and toxic effects of Se occur with exposure to levels of 2–5 ppm Se or more, depending on the chemical form of the Se. Selenium toxicity in livestock is known in a few areas around the world, but Se deficiency has turned out to be much more common than Se toxicity. The Se deficiency problem is severe in New Zealand, in parts of China, in parts of North America, and in the Scandinavian countries.

J. E. Oldfield

Papers

Effects of selenium and vitamin E on white muscle disease.

White muscle disease (myopathy) in lambs and calves. 6. Effects of selenium and vitamin E on lambs.

Feed Additives, Implications of Selenium in Large Animal Nutrition

White muscle disease (myopathy) in lambs and calves. VII. Etiology and prophylaxis.