Aluminum Toxicity and Iron Overload

We end this comparative review of iron and aluminum biochemistry with a consideration of the biochemical consequences of iron overload in animals and their relationship to the effects of elevated levels of aluminum. 

Iron-overload disease, or hemochromatosis, may occur as a consequence of an, as yet, undefined genetic defect, or as a secondary effect of another medical disorder, such as thalassemia. In the former condition, primary hemochromatosis, iron accumulates in various tissues because of a lack of control of iron absorption from the gut. In the latter, or secondary hemochromatosis, the accumulation of iron results from the breakdown of red blood cells and the consequent need for frequent blood transfusions, which lead to an increase in the levels of tissue iron. In both cases the predominant store for iron is hemosiderin (147). 

The level of soluble iron in plasma is raised in cases of iron overload, with iron being bound to proteins, transferrin, and albumin, and with 

Electron microscopy and Mossbauer spectroscopy show (39) that the iron in hemosiderin is in the form of mineral phases, much like the iron core of ferritin. However, hemosiderin is insoluble in water at pH 7 and thus has not been chemically characterized to the same extent as ferritin. Nevertheless, the available evidence favors the formation of hemosiderin from the degradation and aggregation of ferritin (3,148). 

The extensive tissue damage associated with hemochromatosis is usually ascribed to the formation of free radicals that damage subcel-lular membranes, causing the organelles to become leaky (105, 148). However, comparison with aluminum suggests other mechanisms may also be operative. Thus iron, like aluminum (Section III), may cause damage because it displaces magnesium and calcium from key biochemical interaction sites. Also, insoluble iron deposits may stimulate the formation of free radicals, as well as produce them directly, and may activate other defense mechanisms in the body that attempt to remove or sequester particulate matter, as may happen in certain cases of aluminum overload (Section III). 

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D. Aluminum-Citrate Complexes Aluminum Toxicity and Iron Overload References... 

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