RESUMO
El presente trabajo discute la bioquímica del zinc como micronutriente esencial, y su importancia en el organismo debido a la multiplicidad de enzimas y mecanismos hormonales que lo involucran. Se describen sus acciones biológicas en la reproducción, embarazo, crecimiento y maduración infantil, en el desarrollo del sistema nervioso central y los trastornos psíquicos, en el sistema inmunitario y el envejecimiento. Se da una idea de su mecanismo nutricional, requisitos diarios, y efectos sobre su absorción y excreción. Se discute su diagnóstico por medio de su determinación en suero, orina y cabellos y se describen tests complementarios para casos especiales. (AU)
Assuntos
Humanos , Gravidez , Micronutrientes , Zinco/química , Zinco/diagnóstico , Zinco/deficiência , Ciências da Nutrição , Enzimas , Biologia , Oligoelementos , Substâncias de Crescimento/uso terapêutico , Substâncias de Crescimento/deficiência , Fertilidade/efeitos dos fármacos , Anorexia Nervosa , Doenças do Sistema Imunitário , Manifestações Cutâneas , Reprodução , Envelhecimento/efeitos dos fármacosRESUMO
Malnourished children have thymic atrophy which is reversed by zinc supplementation. To see if their defect in cell-mediated immunity was also associated with zinc deficiency ten children were skin-tested with Candida antigen on both arms. One test site was covered with local zinc sulphate and the other with placebo ointment. There was a highly significant increase in the typical delayed-hypersensitivity reaction at the site covered with zinc. The magnitude of the difference between the supplemented and unsupplemented arms correlated negatively with the plasma-zinc concentration. These data show that zinc deficiency is a cause of the immunoincompetence seen in malnutrition. The normal reactions of the zinc-supplemented side indicate that, of the many nutritional deficits of malnourished children, zinc deficiency specifically impairs the cell-mediated immune system. Local skin-testing with and without zinc may provide a measure of zinc status. Local application of zinc may enhanc the reliability of tests to diagnose diseases such as tuberculosis in malnourished patients.(AU)
