Metals in medicine

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Metals in medicine are used in organic systems for diagnostic and treatment purposes. [1] Inorganic elements are also essential for organic life as cofactors in enzymes called metalloproteins. When metals are scarce or high quantities, equilibrium is set out of balance and must be returned to its natural state via interventional and natural methods.

Contents

Toxic metals

Metals can be toxic in high quantities. Either ingestion or faulty metabolic pathways can lead to metal toxicity (metal poisoning). Sources of toxic metals include cadmium from tobacco, arsenic from agriculture and mercury from volcanoes and forest fires. Nature, in the form of trees and plants, is able to trap many toxins and can bring abnormally high levels back into equilibrium. Toxic metal poisoning is usually treated with some type of chelating agent. [2] [3] Heavy metal poisoning, such as from mercury, cadmium, or lead, is particularly pernicious.

Examples of specific types of toxic metals include:

Biometals

Homeostasis

Fluid and electrolyte balance, in which fluid balance and electrolyte balance are intertwined homeostatically, is necessary to health in all organisms. It includes reference ranges for cation concentrations of biometals, which in reference to human medicine and veterinary medicine principally includes those for blood serum ion concentrations in humans and in livestock and pets. Derangements in such fluid and electrolyte balance most often occur in the contexts of dehydration, overexertion, and diarrhea, but they also occur in cancers (most especially in paraneoplastic syndromes), parasitism, inborn errors of metabolism, and several other contexts. Some medical specialties deal especially frequently with electrolyte derangements, including internal medicine and endocrinology (especially in chronic conditions) and intensive care medicine (in severe acute conditions).

Metal anemia

Humans need a certain amount of certain metals to function normally. Most metals are used as cofactors or prosthetics in enzymes, catalyzing specific reactions and serving essential roles. The essential metals for humans are: Sodium, Potassium, Magnesium, Copper, Vanadium, Chromium, Manganese, Iron, Cobalt, Nickel, Zinc, Molybdenum, and Cadmium. Anemia symptoms are caused by lack of a certain essential metal. Anemia can be associated with malnourishment or faulty metabolic processes, usually caused by a genetic defect. [3]

Examples of specific types of metal anemia include:

Metals in diagnosis

Metal complexes in nuclear imaging

Metal ions are often used for diagnostic medical imaging. Metal complexes can be used either for radioisotope imaging (from their emitted radiation) or as contrast agents, for example, in magnetic resonance imaging (MRI). Such imaging can be enhanced by manipulation of the ligands in a complex to create specificity so that the complex will be taken up by a certain cell or organ type. [3] [4]

Figure 1. Structure of Bleomycin A2 Bleomycin A2.svg
Figure 1. Structure of Bleomycin A2

Examples of metals used for diagnosis include:

Metal objects in MRI imaging

An important contraindication to MRI (magnetic resonance imaging) is having metal objects anywhere near, and most especially inside the field of, the MRI scanner. Not only does this entail that people with implanted metal plates, bone screws (internal fixation), or syndesmotic screws often cannot undergo MRI, it also entails that many everyday objects, including jewelry, belt buckles, wallets, purses, security guards' weapons, and so on, must be kept out of the MRI area.

Metals in treatment

Metals have been used in treatments since ancient times. The Ebers Papyrus from 1500BC is the first written account of the use of metals for treatment and describes the use of Copper to reduce inflammation and the use of iron to treat anemia. Sodium vanadate has been used since the early 20th century to treat rheumatoid arthritis. Recently metals have been used to treat cancer, by specifically attacking cancer cells and interacting directly with DNA. The positive charge on most metals can interact with the negative charge of the phosphate backbone of DNA. Some drugs developed that include metals interact directly with other metals already present in protein active sites, while other drugs can use metals to interact with amino acids with the highest reduction potential. [4]

Figure 2. Structure of Cisplatin, a platinum coordination complex. Cisplatin-stereo.svg
Figure 2. Structure of Cisplatin, a platinum coordination complex.

Examples of metals used in treatment include:

Figure 3. Structure of Sodium aurothiomalate, a gold salt complex. Sodium aurothiomalate.svg
Figure 3. Structure of Sodium aurothiomalate, a gold salt complex.
Figure 4. Structure of bismuth subsalicylate. Bismuth subsalicylate.png
Figure 4. Structure of bismuth subsalicylate.

See also

Related Research Articles

<span class="mw-page-title-main">Cadmium</span> Chemical element, symbol Cd and atomic number 48

Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, silvery-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Like zinc, it demonstrates oxidation state +2 in most of its compounds, and like mercury, it has a lower melting point than the transition metals in groups 3 through 11. Cadmium and its congeners in group 12 are often not considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states. The average concentration of cadmium in Earth's crust is between 0.1 and 0.5 parts per million (ppm). It was discovered in 1817 simultaneously by Stromeyer and Hermann, both in Germany, as an impurity in zinc carbonate.

<span class="mw-page-title-main">Toxic heavy metal</span> Category of substances

A toxic heavy metal is any relatively dense metal or metalloid that is noted for its potential toxicity, especially in environmental contexts. The term has particular application to cadmium, mercury and lead, all of which appear in the World Health Organization's list of 10 chemicals of major public concern. Other examples include manganese, chromium, cobalt, nickel, copper, zinc, silver, antimony and thallium.

Beryllium copper (BeCu), also known as copper beryllium (CuBe), beryllium bronze, and spring copper, is a copper alloy with 0.5–3% beryllium. Copper beryllium alloys are often used because of their high strength and good conductivity of both heat and electricity. It is used for its ductility, weldability in metalworking, and machining properties. It has many specialized applications in tools for hazardous environments, musical instruments, precision measurement devices, bullets, and some uses in the field of aerospace. Beryllium copper and other beryllium alloys are harmful carcinogens that present a toxic inhalation hazard during manufacturing.

<span class="mw-page-title-main">Metalloprotein</span> Protein that contains a metal ion cofactor

Metalloprotein is a generic term for a protein that contains a metal ion cofactor. A large proportion of all proteins are part of this category. For instance, at least 1000 human proteins contain zinc-binding protein domains although there may be up to 3000 human zinc metalloproteins.

A trace element is a chemical element of a minute quantity, a trace amount, especially used in referring to a micronutrient, but is also used to refer to minor elements in the composition of a rock, or other chemical substance.

<span class="mw-page-title-main">Metallothionein</span> Family of proteins

Metallothionein (MT) is a family of cysteine-rich, low molecular weight proteins. They are localized to the membrane of the Golgi apparatus. MTs have the capacity to bind both physiological and xenobiotic heavy metals through the thiol group of its cysteine residues, which represent nearly 30% of its constituent amino acid residues.

<span class="mw-page-title-main">Group 12 element</span> Group of chemical elements

Group 12, by modern IUPAC numbering, is a group of chemical elements in the periodic table. It includes zinc (Zn), cadmium (Cd), mercury (Hg), and copernicium (Cn). Formerly this group was named IIB by CAS and old IUPAC system.

<span class="mw-page-title-main">Dimercaprol</span> Chemical compound

Dimercaprol, also called British anti-Lewisite (BAL), is a medication used to treat acute poisoning by arsenic, mercury, gold, and lead. It may also be used for antimony, thallium, or bismuth poisoning, although the evidence for those uses is not very strong. It is given by injection into a muscle.

Bioinorganic chemistry is a field that examines the role of metals in biology. Bioinorganic chemistry includes the study of both natural phenomena such as the behavior of metalloproteins as well as artificially introduced metals, including those that are non-essential, in medicine and toxicology. Many biological processes such as respiration depend upon molecules that fall within the realm of inorganic chemistry. The discipline also includes the study of inorganic models or mimics that imitate the behaviour of metalloproteins.

Cadmium is a naturally occurring toxic metal with common exposure in industrial workplaces, plant soils, and from smoking. Due to its low permissible exposure in humans, overexposure may occur even in situations where trace quantities of cadmium are found. Cadmium is used extensively in electroplating, although the nature of the operation does not generally lead to overexposure. Cadmium is also found in some industrial paints and may represent a hazard when sprayed. Operations involving removal of cadmium paints by scraping or blasting may pose a significant hazard. The primary use of cadmium is in the manufacturing of NiCd rechargeable batteries. The primary source for cadmium is as a byproduct of refining zinc metal. Exposures to cadmium are addressed in specific standards for the general industry, shipyard employment, the construction industry, and the agricultural industry.

Metal fume fever, also known as brass founders' ague, brass shakes, zinc shakes, galvie flu, galvo poisoning, metal dust fever, welding shivers, or Monday morning fever, is an illness primarily caused by exposure to chemicals such as zinc oxide (ZnO), aluminium oxide (Al2O3), or magnesium oxide (MgO) which are produced as byproducts in the fumes that result when certain metals are heated. Other common sources are fuming silver, gold, platinum, chromium (from stainless steel), nickel, arsenic, manganese, beryllium, cadmium, cobalt, lead, selenium, and zinc.

<span class="mw-page-title-main">Biometal (biology)</span> Metal in biology, biochemistry, and medicine

Biometals are metals normally present, in small but important and measurable amounts, in biology, biochemistry, and medicine. The metals copper, zinc, iron, and manganese are examples of metals that are essential for the normal functioning of most plants and the bodies of most animals, such as the human body. A few are present in relatively larger amounts, whereas most others are trace metals, present in smaller but important amounts. Approximately 2/3 of the existing periodic table is composed of metals with varying properties, accounting for the diverse ways in which metals have been utilized in nature and medicine.

<span class="mw-page-title-main">Copper deficiency</span> Insufficient level of copper in the body, leading to anaemia and nervous symptoms

Copper deficiency, or hypocupremia, is defined either as insufficient copper to meet the needs of the body, or as a serum copper level below the normal range. Symptoms may include fatigue, decreased red blood cells, early greying of the hair, and neurological problems presenting as numbness, tingling, muscle weakness, and ataxia. The neurodegenerative syndrome of copper deficiency has been recognized for some time in ruminant animals, in which it is commonly known as "swayback". Copper deficiency can manifest in parallel with vitamin B12 and other nutritional deficiencies.

Metal toxicity or metal poisoning is the toxic effect of certain metals in certain forms and doses on life. Some metals are toxic when they form poisonous soluble compounds. Certain metals have no biological role, i.e. are not essential minerals, or are toxic when in a certain form. In the case of lead, any measurable amount may have negative health effects. It is often thought that only heavy metals can be toxic, but lighter metals such as beryllium and lithium may also be in certain circumstances. Not all heavy metals are particularly toxic, and some are essential, such as iron. The definition may also include trace elements when abnormally high doses may be toxic. An option for treatment of metal poisoning may be chelation therapy, a technique involving the administration of chelation agents to remove metals from the body.

<span class="mw-page-title-main">Zinc protoporphyrin</span> Chemical compound

Zinc protoporphyrin (ZPP) refers to coordination complexes of zinc and protoporphyrin IX. It is a red-purple solid that is soluble in water. The complex and related species are found in red blood cells when heme production is inhibited by lead and/or by lack of iron.

<span class="mw-page-title-main">Copper toxicity</span> Type of metal poisoning

Copper toxicity is a type of metal poisoning caused by an excess of copper in the body. Copperiedus could occur from consuming excess copper salts, but most commonly it is the result of the genetic condition Wilson's disease and Menke's disease, which are associated with mismanaged transport and storage of copper ions. Copper is essential to human health as it is a component of many proteins. But hypercupremia can lead to copper toxicity if it persists and rises high enough.

Heavy metal detox, or detoxification, is the removal of metallic toxic substances from the body. In conventional medicine, detoxification can also be achieved artificially by techniques such as dialysis and chelation therapy. There is a firm scientific base in evidence-based medicine for this type of detoxification. Many alternative medicine practitioners promote various other types of detoxification such as "diet detoxification".

<span class="mw-page-title-main">Copper in biology</span> Description of the elements function as an essential trace element

Copper is an essential trace element that is vital to the health of all living things. In humans, copper is essential to the proper functioning of organs and metabolic processes. The human body has complex homeostatic mechanisms which attempt to ensure a constant supply of available copper, while eliminating excess copper whenever this occurs. However, like all essential elements and nutrients, too much or too little nutritional ingestion of copper can result in a corresponding condition of copper excess or deficiency in the body, each of which has its own unique set of adverse health effects.

<span class="mw-page-title-main">Heavy metals</span> Loosely defined subset of elements that exhibit metallic properties

Heavy metals are generally defined as metals with relatively high densities, atomic weights, or atomic numbers. The criteria used, and whether metalloids are included, vary depending on the author and context. In metallurgy, for example, a heavy metal may be defined on the basis of density, whereas in physics the distinguishing criterion might be atomic number, while a chemist would likely be more concerned with chemical behaviour. More specific definitions have been published, none of which have been widely accepted. The definitions surveyed in this article encompass up to 96 out of the 118 known chemical elements; only mercury, lead and bismuth meet all of them. Despite this lack of agreement, the term is widely used in science. A density of more than 5 g/cm3 is sometimes quoted as a commonly used criterion and is used in the body of this article.

References

  1. Carver, Peggy L. (2019). "Chapter 1. Essential Metals in Medicine: The therapeutic Use of Metal Ions in the Clinic". In Sigel, Astrid; Freisinger, Eva; Sigel, Roland K. O.; Carver, Peggy L. (Guest editor) (eds.). Essential Metals in Medicine:Therapeutic Use and Toxicity of Metal Ions in the Clinic. pp. 1–16. doi:10.1515/9783110527872-007. ISBN   978-3-11-052691-2. PMID   30855102. S2CID   214079687.{{cite book}}: |editor4-first= has generic name (help); |journal= ignored (help)
  2. Nash, Robert A. “Metals in Medicine.” Alternative Therapies II.4 (2005):18-25.
  3. 1 2 3 4 5 6 7 Lippard, Stephen J. “Metals in Medicine.” Bioinorganic Chemistry. Mill City: University Science Books, 1994. 505-583.
  4. 1 2 Dabrowiak, James C. “Metals in Medicine.” Inorganic Chemica Acta. (2012). Preface.