22 research outputs found

    Prostate cancer risk and DNA damage: translational significance of selenium supplementation in a canine model

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    Daily supplementation with the essential trace mineral selenium significantly reduced prostate cancer risk in men in the Nutritional Prevention of Cancer Trial. However, the optimal intake of selenium for prostate cancer prevention is unknown. We hypothesized that selenium significantly regulates the extent of genotoxic damage within the aging prostate and that the relationship between dietary selenium intake and DNA damage is non-linear, i.e. more selenium is not necessarily better. To test this hypothesis, we conducted a randomized feeding trial in which 49 elderly beagle dogs (physiologically equivalent to 62--69-year-old men) received nutritionally adequate or supranutritional levels of selenium for 7 months, in order to mimic the range of dietary selenium intake of men in the United States. Our results demonstrate an intriguing U-shaped dose--response relationship between selenium status (toenail selenium concentration) and the extent of DNA damage (alkaline Comet assay) within the prostate. Further, we demonstrate that the concentration of selenium that minimizes DNA damage in the aging dog prostate remarkably parallels the selenium concentration in men that minimizes prostate cancer risk. By studying elderly dogs, the only non-human animal model of spontaneous prostate cancer, we have established a new approach to bridge the gap between laboratory and human studies that can be used to select the appropriate dose of anticancer agents for large-scale human cancer prevention trials. From the U-shaped dose--response, it follows that not all men will necessarily benefit from increasing their selenium intake and that measurement of baseline nutrient status should be required for all individuals in prevention trials to avoid oversupplementation

    Plasma and breast-milk selenium in HIV-infected Malawian mothers are positively associated with infant selenium status but are not associated with maternal supplementation: results of the Breastfeeding, Antiretrovirals, and Nutrition study

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    Background: Selenium is found in soils and is essential for human antioxidant defense and immune function. In Malawi, low soil selenium and dietary intakes coupled with low plasma selenium concentrations in HIV infection could have negative consequences for the health of HIV-infected mothers and their exclusively breastfed infants

    Determinants of selenium status in healthy adults

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    <p>Abstract</p> <p>Background</p> <p>Selenium (Se) status in non-deficient subjects is typically assessed by the Se contents of plasma/serum. That pool comprises two functional, specific selenoprotein components and at least one non-functional, non-specific components which respond differently to changes in Se intake. A more informative means of characterizing Se status in non-deficient individuals is needed.</p> <p>Methods</p> <p>Multiple biomarkers of Se status (plasma Se, serum selenoprotein P [SEPP1], plasma glutathione peroxidase activity [GPX3], buccal cell Se, urinary Se) were evaluated in relation to selenoprotein genotypes (GPX1, GPX3, SEPP1, SEP15), dietary Se intake, and parameters of single-carbon metabolism in a cohort of healthy, non-Se-deficient men (n = 106) and women (n = 155).</p> <p>Conclusions</p> <p>Plasma Se concentration was 142.0 ± 23.5 ng/ml, with GPX3 and serum-derived SEPP1 calculated to comprise 20% and 34%, respectively, of that total. The balance, comprised of non-specific components, accounted for virtually all of the interindividual variation in total plasma Se. Buccal cell Se was associated with age and plasma homocysteine (hCys), but not plasma Se. SEPP1 showed a quadratic relationship with body mass index, peaking at BMI 25-30. Urinary Se was greater in women than men, and was associated with metabolic body weight (kg<sup>0.75</sup>), plasma folate, vitamin B<sub>12 </sub>and hCys (negatively). One <it>GPX1 </it>genotype (679T/T) was associated with significantly lower plasma Se levels than other allelic variants. Selenium intake, estimated from food frequency questionnaires, did not predict Se status as indicated by any biomarker. These results show that genotype, methyl-group status and BMI contribute to variation in Se biomarkers in Se-adequate individuals.</p

    Finishing the euchromatic sequence of the human genome

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    The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

    The Vitamins : Fundamental Aspects in Nutrition and Health.

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    The third edition of this bestselling text will again provide the latest coverage of the biochemistry and physiology of vitamins and vitamin-like substances. Extensively revised and expanded on the basis of recent research findings with enlarged coverage of health effects of vitamin-like factors, it is ideally suited for students and an important reference for anyone interested in nutrition, food science, animal science or endocrinology. It contains a cohesive and well-organized presentation of each of the vitamins, as well as the history of their discoveries and current information about their roles in nutrition and health. NEW TO THIS EDITION: *Includes approximately 30% new material *Substantial updates have been made to chapters on vitamins A, C, E, K, folate, and the quasi-vitamins *Provides checklists of systems affected by vitamin deficiencies and food sources of vitamins *Key concepts, learning objectives, vocabulary,case studies, study questions and additional reading lists are included making this ideally suited for students * Thoroughly updated with important recent research results, including citations to key reports, many added tables and several new figures. *Addition of Health and Nutrition Examination Survey (HANES III) data *Updated Dietary Reference Values.Front Cover -- The Vitamins -- Copyright Page -- Dedication Page -- Contents -- Preface -- Preface to the Second Edition -- Preface to the First Edition -- How to Use This Book -- Part I: Perspectives on the Vitamins in Nutrition -- Chapter I: What is a Vitamin? -- I. Thinking about Vitamins -- II. Vitamin: A Revolutionary Concept -- III. An Operating Definition of a Vitamin -- IV. The Recognized Vitamins -- Study Questions -- Chapter 2: Discovery of the Vitamins -- I. The Emergence of Nutrition as a Science -- II. The Process of Discovery in Nutritional Science -- III. The Empirical Phase of Vitamin Discovery -- IV. The Experimental Phase of Vitamin Discovery -- V. The Vitamine Theory -- VI. Elucidation of the Vitamins -- VII. Vitamin Terminology -- VIII. Other Factors Sometimes Called Vitamins -- IX. The Modern History of the Vitamins -- Study Questions and Exercises -- Recommended Reading -- Chapter 3: Chemical and Physiological Properties of the Vitamins -- I. Chemical and Physical Properties of the Vitamins -- II. Vitamin A -- III. Vitamin D -- IV. Vitamin E -- V. Vitamin K -- VI. Vitamin C -- VII. Thiamin -- VIII. Riboflavin -- IX. Niacin -- X. Vitamin B6 -- XI. Biotin -- XII. Pantothenic Acid -- XIII. Folate -- XIV. Vitamin B12 -- XV. General Properties of the Vitamins -- XVI. Physiological Utilization of the Vitamins -- XVII. Metabolism of the Vitamins -- XVIII. Metabolic Functions of the Vitamins -- Study Questions and Exercises -- Recommended Reading -- Chapter 4: Vitamin Deficiency -- I. The Concept of Vitamin Deficiency -- II. The Many Causes of Vitamin Deficiencies -- III. Clinical Manifestations of Vitamin Deficiencies -- IV. Vitamin Deficiency Diseases: Manifestations of Biochemical Lesions -- Study Questions and Exercises -- Recommended Reading -- Part II: Considering the Individual Vitamins -- Chapter 5: Vitamin A.I. Significance of Vitamin A -- II. Sources of Vitamin A -- III. Absorption of Vitamin A -- IV. Transport of Vitamin A -- V. Metabolism of Vitamin A -- VI. Excretion of Vitamin A -- VII. Metabolic Functions of Vitamin A -- VIII. Vitamin A Deficiency -- IX. Vitamin A Toxicity -- X. Case Studies -- Study Questions and Exercises -- Recommended Reading -- Chapter 6: Vitamin D -- I. Significance of Vitamin D -- II. Sources of Vitamin D -- III. Enteric Absorption of Vitamin D -- IV. Transport of Vitamin D -- V. Metabolism of Vitamin D -- VI. Metabolic Functions of Vitamin D -- VII. Vitamin D Deficiency -- VIII. Vitamin D Toxicity -- IX. Case Studies -- Study Questions and Exercises -- Recommended Reading -- Chapter 7: Vitamin E -- I. The Significance of Vitamin E -- II. Sources of Vitamin E -- III. Absorption of Vitamin E -- IV. Transport of Vitamin E -- V. Metabolism of Vitamin E -- VI. Metabolic Functions of Vitamin E -- VII. Vitamin K Deficiency -- VIII. Pharmacologic Uses of Vitamin E -- IX. Vitamin K Toxicity -- X. Case Studies -- Study Questions and Exercises -- Recommended Reading -- Chapter 8: Vitamin K -- I. The Significance of Vitamin K -- II. Sources of Vitamin K -- III. Absorption of Vitamin K -- IV. Transport of Vitamin K -- V. Metabolism of Vitamin K -- VI. Metabolic Functions of Vitamin K -- VII. Vitamin K Deficiency -- VIII. Vitamin K Toxicity -- IX. Case Studies -- Study Questions and Exercises -- Recommended Reading -- Chapter 9: Vitamin C -- I. The Significance of Vitamin C -- II. Sources of Vitamin C -- III. Absorption of Vitamin C -- IV. Transport of Vitamin C -- V. Metabolism of Vitamin C -- VI. Metabolic Functions of Vitamin C -- VII. Vitamin C Deficiency -- VIII. Pharmacological Uses of Vitamin C -- IX. Vitamin C Toxicity -- X. Case Studies -- Study Questions and Exercises -- Recommended Reading -- Chapter 10: Thiamin.I. The Significance of Thiamin -- II. Sources of Thiamin -- III. Absorption of Thiamin -- IV. Transport of Thiamin -- V. Metabolism of Thiamin -- VI. Metabolic Functions of Thiamin -- VII. Thiamin Deficiency -- VIII. Thiamin Toxicity -- IX. Case Studies -- Study Questions and Exercises -- Recommended Reading -- Chapter 11: Riboflavin -- I. The Significance of Riboflavin -- II. Sources of Riboflavin -- III. Absorption of Riboflavin -- IV. Transport of Riboflavin -- V. Metabolism of Riboflavin -- VI. Metabolic Functions of Riboflavin -- VII. Riboflavin Deficiency -- VIII. Riboflavin Toxicity -- IX. Case Study -- Study Questions and Exercises -- Recommended Reading -- Chapter 12: Niacin -- I. The Significance of Niacin -- II. Sources of Niacin -- III. Absorption of Niacin -- IV. Transport of Niacin -- V. Metabolism of Niacin -- VI. Metabolic Functions of Niacin -- VII. Niacin Deficiency -- VIII. Pharmacologic Uses of Niacin -- IX. Niacin Toxicity -- X. Case Study -- Study Questions and Exercises -- Recommended Reading -- Chapter 13: Vitamin B6 -- I. The Significance of Vitamin B6 -- II. Sources of Vitamin B6 -- III. Absorption of Vitamin B6 -- IV. Transport of Vitamin B6 -- V. Metabolism of Vitamin B6 -- VI. Metabolic Functions of Vitamin B6 -- VII. Vitamin B6 Deficiency -- VIII. Pharmacologic Uses of Vitamin B6 -- IX. Vitamin B6 Toxicity -- X. Case Studies -- Study Questions and Exercises -- Recommended Reading -- Chapter 14: Biotin -- I. The Significance of Biotin -- II. Sources of Biotin -- III. Absorption of Biotin -- IV. Transport of Biotin -- V. Metabolism of Biotin -- VI. Metabolic Functions of Biotin -- VII. Biotin Deficiency -- VIII. Biotin Toxicity -- IX. Case Study -- Study Questions and Exercises -- Recommended Reading -- Chapter 15: Pantothenic Acid -- I. The Significance of Pantothenic Acid -- II. Sources of Pantothenic Acid.III. Absorption of Pantothenic Acid -- IV. Transport of Pantothenic Acid -- V. Metabolism of Pantothenic Acid -- VI. Metabolic Functions of Pantothenic Acid -- VII. Pantothenic Acid Deficiency -- VIII. Pantothenic Acid Toxicity -- IX. Case Study -- Study Questions and Exercises -- Recommended Reading -- Chapter 16: Folate -- I. The Significance of Folate -- II. Sources of Folate -- III. Absorption of Folate -- IV. Transport of Folate -- V. Metabolism of Folate -- VI. Metabolic Functions of Folate -- VII. Folate Deficiency -- VIII. Pharmacologic Uses of Folate -- IX. Folate Toxicity -- X. Case Study -- Study Questions and Exercises -- Recommended Reading -- Chapter 17: Vitamin B12 -- I. The Significance of Vitamin B12 -- II. Sources of Vitamin B12 -- III. Absorption of Vitamin B12 -- IV. Transport of Vitamin B12 -- V. Metabolism of Vitamin B12 -- VI. Metabolic Functions of Vitamin B12 -- VII. Vitamin B12 Deficiency -- VIII. Vitamin B12 Toxicity -- IX. Case Study -- Study Questions and Exercises -- Recommended Reading -- Chapter 18: Quasi-vitamins -- I. Is the List of Vitamins Complete? -- II. Choline -- III. Carnitine -- IV. myo-Inositol -- V. Pyrroloquinoline Quinone -- VI. Ubiquinones -- VII. Flavonoids -- VIII. Non-Provitamin A Carotenoids -- IX. Orotic Acid -- X. p-Aminobenzoic Acid -- XI. Lipoic Acid -- XII. Ineffective Factors -- XIII. Unidentified Growth Factors -- Study Questions and Exercises -- Recommended Reading -- Part III: Using Current Knowledge of the Vitamins -- Chapter 19: Sources of the Vitamins -- I. Vitamins in Foods -- II. Vitamin Contents of Feedstuffs -- III. Predicting Vitamin Contents -- IV. Vitamin Bioavailability -- V. Vitamin Losses -- VI. Vitamin Supplementation and Fortification of Foods -- VII. Vitamins in Human Diets -- VIII. Vitamin Supplements -- IX. Vitamin Labeling of Foods -- X. Vitamins in Livestock Feeds.Study Questions and Exercises -- Recommended Reading -- Chapter 20: Assessing Vitamin Status -- I. General Aspects of Nutritional Assessment -- II. Assessment of Vitamin Status -- III. Vitamin Status of Human Populations -- Study Questions and Exercises -- Recommended Reading -- Chapter 21: Quantifying Vitamin Needs -- I. Dietary Standards -- II. Determining Dietary Standards for Vitamins -- III. Factors Affecting Vitamin Requirements -- IV. Vitamin Allowances for Humans -- V. Vitamin Allowances for Animals -- Study Questions and Exercises -- Recommended Reading -- Chapter 22: Vitamin Safety -- I. Uses of Vitamins above Required Levels -- II. Hazards of Excessive Vitamin Intakes -- III. Signs of Hypervitaminoses -- IV. Safe Intakes of Vitamins -- Study Questions and Exercises -- Recommended Reading -- Appendices -- Appendix A: Vitamin Terminology: Past and Present -- Appendix B: Original Reports for Case Studies -- Appendix C: A Core of Current Vitamin Research Literature -- Appendix D: Vitamin Contents of Foods -- Appendix E: Vitamin Contents of Feedstuffs -- Index.The third edition of this bestselling text will again provide the latest coverage of the biochemistry and physiology of vitamins and vitamin-like substances. Extensively revised and expanded on the basis of recent research findings with enlarged coverage of health effects of vitamin-like factors, it is ideally suited for students and an important reference for anyone interested in nutrition, food science, animal science or endocrinology. It contains a cohesive and well-organized presentation of each of the vitamins, as well as the history of their discoveries and current information about their roles in nutrition and health. NEW TO THIS EDITION: *Includes approximately 30% new material *Substantial updates have been made to chapters on vitamins A, C, E, K, folate, and the quasi-vitamins *Provides checklists of systems affected by vitamin deficiencies and food sources of vitamins *Key concepts, learning objectives, vocabulary,case studies, study questions and additional reading lists are included making this ideally suited for students * Thoroughly updated with important recent research results, including citations to key reports, many added tables and several new figures. *Addition of Health and Nutrition Examination Survey (HANES III) data *Updated Dietary Reference Values.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, 2017. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries

    Biomarkers of Selenium Status

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    The essential trace element, selenium (Se), has multiple biological activities, which depend on the level of Se intake. Relatively low Se intakes determine the expression of selenoenzymes in which it serves as an essential constituent. Higher intakes have been shown to have anti-tumorigenic potential; and very high Se intakes can produce adverse effects. This hierarchy of biological activities calls for biomarkers informative at different levels of Se exposure. Some Se-biomarkers, such as the selenoproteins and particularly GPX3 and SEPP1, provide information about function directly and are of value in identifying nutritional Se deficiency and tracking responses of deficient individuals to Se-treatment. They are useful under conditions of Se intake within the range of regulated selenoprotein expression, e.g., for humans &lt;55 μg/day and for animals &lt;20 μg/kg diet. Other Se-biomarkers provide information indirectly through inferences based on Se levels of foods, tissues, urine or feces. They can indicate the likelihood of deficiency or adverse effects, but they do not provide direct evidence of either condition. Their value is in providing information about Se status over a wide range of Se intake, particularly from food forms. There is need for additional Se biomarkers particularly for assessing Se status in non-deficient individuals for whom the prospects of cancer risk reduction and adverse effects risk are the primary health considerations. This would include determining whether supranutritional intakes of Se may be required for maximal selenoprotein expression in immune surveillance cells. It would also include developing methods to determine low molecular weight Se-metabolites, i.e., selenoamino acids and methylated Se-metabolites, which to date have not been detectable in biological specimens. Recent analytical advances using tandem liquid chromatography-mass spectrometry suggest prospects for detecting these metabolites

    Importance of selenium in human nutrition

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    In the span of five decades, Se has moved from being thought of as a toxicant to being considered essential nutrient. The elucidation of its role in nutrition has led to fundamental discoveries in metabolic biochemistry (the unique metabolism of SeCys), virology (the destabilization of RNA viruses due to oxidative stress), and public health (the role in cancer risk reduction). Unlike most other nutrients, which were recognized due to the fatal outcomes of their deficiencies, the consequences of Se deprivation appear to be largely sub-clinical in nature, requiring other precipitating factors (e.g., vitamin E deficiency, viral exposure, etc.) to reveal the effects of compromised Se-enzymes and/or essential Se-metabolites. Even after a half-century of research, much remains to learn about the metabolic bases of the roles of Se in nutrition and health.vokMyynti MTT tietopalvelut 31600 Jokioine
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