Date of Award


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First Reader

Dr. Joe Nix


Heavy metals, although only in traces, are essential for all forms of life. They are taken up by the living cell in the form of cations, and their uptake is strictly regulated because most or all of them are toxic in excess. A remarkable specificity has been found: seldom can an excess of one essential metal prevent the damage caused by deficiency of another. In fact, such an excess often increase the injurious effect of deficiency.

Metal-binding substances, many of which function by chelation, form a class of substances which have furnished many useful drugs and other substances of value in selective toxicity. They are manufactured in huge quantities for this purpose, particularly those that are used in agriculture as fungicides. They function by upsetting the delicate balance of trace heavy metals. Some of them withdraw metals from living tissues, but many others reinforce, strongly, the natural toxicity of heavy metal.

Apart from their use as agricultural fungicides, metal-binding substances have found three types of use in veterinary and human medicine. Some are used to differentiate between vertebrates and their parasites. Such substances make a valuable contribution to the fight against fungi, bacteria, and viruses. Others, which may be described as antidotes, are used to distinguish between essential and poisonous metals. The third type is required to differentiate between normal and pathological processes, e.g. in rheumatic diseases, cardiovascular disease, and cancer.



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