Zinc-deficiency hypothesis

It was appreciated later that zinc might be fundamental to the pathogenesis of this rare inherited disorder and that the clinical improvement reflected improvement in zinc status. Support for zinc deficiency hypothesis came from the observation that a close resemblance between the symptoms of zinc deficiency in animals and man as reported earlier (85) and... 

Bin QH, Garfinkel D. The cadmium toxicity hypothesis of aging A possible explanation for the zinc deficiency hypothesis of aging. Med Hypotheses 1994 42 380-4. 

Subsequent reports from numerous laboratories have reinforced that hypothesis. Studies with both ruminants (2) and rats (3,4) have shown zinc absorption is depressed by high levels of dietary zinc. Conversely, zinc deficiency results in an... 

The mechanism by which zinc mediates Immune function is not clear the depression of DNA synthesis during zinc deficiency is implicated (9. McCaffrey et al. (97) demonstrated that a zinc-containing DNA polymerase is present in the thymus but does not appear in the mature T cell. A reduction in thymus tissue caused by zinc deficiency would adversely affect the immunocompetence of thymocytes. This hypothesis has been confirmed in experiments where a sharp drop in the thymic hormone is induced by zinc deficiency. 

Deficiency hypothesis Substances which are essential to the smooth functioning of the central nervous system are not provided, or are only inadequately provided, by a seriously damaged liver. This hypothesis relates to the branched-chain amino acids as well as cellular deficits of zinc, potassium, magnesium and unsaturated fatty acids. 

A number of agents have been studied for their effects on processes which are thought to be important factors in aging. One hypothesis suggests that an intracellular zinc deficiency may be a primary cause of the aging process (63) since zinc-metaUoenzymes pla.y an important role in many aspects of cellular metabolisiiL A zinc deficiency could result in malproduction of proteins and an accumulation of useless or toxic materials. However, apart from the immune response studies, no therapeutic trials have been conducted to evaluate this hypothesis. 

The maintenance of optimal zinc levels in bacteria is required for cell function and survival. In an effort to probe the cellular response to Zn(II) deficient and excess stresses and to identify any potential cytoplasmic Zn(II)-metallochaperones, DNA microarrays were used. Although many Zn(II)-responsive genes were identified, no plausible candidates for cytoplasmic Zn(II)-metallochaperones were identified. This result warrants a new model to explain intracellular Zn(II) transport in bacteria, and a novel hypothesis that involves a role of the ribosomes in Zn(II) storage and transport is offered. 

These Fe deficiency-induced processes are likely to operate ubiquitously in soils because of limited bioavailability of Fe, especially in neutral to alkaline soils. Iron deficiency in crops may thus affect metal speciation in soil, and ultimately enhance the uptake of metals by plants. In the present study, we examined this hypothesis in the case of copper (Cu) and zinc (Zn), which are micronutrients and also potential metal contaminants. 

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