931 resultados para Deficiencia de vitamina B12


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A widespread and complex distribution of vitamin requirements exists over the entire tree of life, with many species having evolved vitamin dependence, both within and between different lineages. Vitamin availability has been proposed to drive selection for vitamin dependence, in a process that links an organism's metabolism to the environment, but this has never been demonstrated directly. Moreover, understanding the physiological processes and evolutionary dynamics that influence metabolic demand for these important micronutrients has significant implications in terms of nutrient acquisition and, in microbial organisms, can affect community composition and metabolic exchange between coexisting species. Here we investigate the origins of vitamin dependence, using an experimental evolution approach with the vitamin B(12)-independent model green alga Chlamydomonas reinhardtii. In fewer than 500 generations of growth in the presence of vitamin B(12), we observe the evolution of a B(12)-dependent clone that rapidly displaces its ancestor. Genetic characterization of this line reveals a type-II Gulliver-related transposable element integrated into the B(12)-independent methionine synthase gene (METE), knocking out gene function and fundamentally altering the physiology of the alga.

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Introduction: An association between depression and folate has been found in clinical studies. Depression and dementia can contribute to nutritional deficiency. This study clinical depression in in octo/nonagenarians from the BELFAST study.
Method: In the BELFAST study, 38 free-living octo/nonagenarians (mean age 82 years), who apparently well and cognitively intact were followed up at 5 years and assessed using the Geriatric Depression Scale (GDS), Folstein (30 point), Mini Nutritional Assessment Tool (MNA) together with serum folate and vitamin B12 levels.
Results: Mean GDS was 3.4 (SD 2.5), serum folate 7.1 umol/l (SD 5.3) and B12 553 umol/l (458). With mean MNA and Folstein -25.8 (SD 2.7) and 27.6 (SD 2.7) respectively with no sex difference (p = 0.78; p = 0.36). 25% of subjects showed a GDS >5 indicating risk of mild depression and 21% had compromised nutritional status. MNA associated with GDS in male (r2 = 0.56 p = 0.01), but not in female elderly subjects (r2 = 0.01; p = 0.44). GDS score and lower serum folate were associated (r2 = -0.23; p = 0.01).
Conclusion: Overall there was the suggestion that nutritional status and depression might be linked in male subjects at 5 year follow-up in octo/nonagenarians from the BEFLAST study. The lower folate in subjects categorised at risk of mild depression might suggest vitamin supplementation could be useful.

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Thesis (Ph.D.)--University of Washington, 2015

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Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Química e Biológica

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Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Química e Biológica

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Tesis (Maestría en Ciencias con Especialidad en Biología Molecular e Ingeniería Genética) UANL

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Tesis (Maestría en Ciencias con Especialidad en Biología Moleculare Ingeniería Genética) UANL

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Tesis (Maestría en Ciencias con Especialidad en Biología Molecular e Ingeniería Genética) UANL

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Tesis (Especialidad en Ortopedia y Traumatología). U. A. N. L.

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Tesis (Maestría en Ciencias con Especialidad en Recursos Alimenticios y Producción Acuícola) U.A.N.L. Facultad de Ciencias Biológicas.