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Toxins
ToxinsToxins are harmful compounds that are produced and released by a variety of microorganisms and other organisms. Toxins can be fast-acting and, because they are already pre-formed, do not require the growth of a microorganism in the host. The illness and death that result from exposure to a variety of toxins make their detection a central part of forensic science . Toxins are the main disease-causing factor for a number of bacteria. Some examples include Coryne-bacterium diphtheriae (diptheria), Vibrio cholerae (cholera), Bacillus anthracis (anthrax ), Clostridium botulinum (botulism), certain strains of Escherichia coli (hemolytic uremic syndrome), and Staphylococcus aureus (toxic shock syndrome). Certain species of these bacteria are of particular concern in biological warfare and biological terrorism. As the events of 2001 in the United States demonstrated, powdered preparations of Bacillus anthracis spores were easily delivered to a target through the mail. The dispersal of the spores in the air and the inhalation of the spores can cause a form of anthrax that develops quickly and, without treatment, is almost always fatal. The bacteria in the genus Clostridium also form spores. Additionally, during the 1990s, a strain of Staphylococcus aureus emerged that is resistant to almost all known antibiotics . Bacterial toxins have a wide variety of activity. Some toxins damage the cell walls of host cells, either by dissolving the wall or by chemically punching holes through the wall. Examples of such toxins are the alpha toxin of Clostridium perfringens, hemolysin of Escherichia coli, and streptokinase of Streptococcus pyogenes. The damage to the host cells allows the bacteria to spread rapidly through the host. This can cause an overwhelming infection. Other bacterial toxins kill host cells by stopping the manufacture of protein in host cells, or by degrading the proteins. Examples of protein blockers include exotoxin A of Pseudomonas aeruginosa and the Shiga toxins produced by both Escherichia coli and Shigella dysenteriae. Protein degrading toxins include those produced by Bacillus anthracis and Clostridium botulinum Still other toxins stimulate an immune response of the host that is so strong that it can damage the host. The toxic shock syndrome associated with Staphylococcus aureus results from a host hyperimmune response to three of the bacterial proteins. Other microorganisms also produce toxins. Marine microorganisms called dinoflagellates can produce toxins when they grow in species of shellfish. Eating the toxic shellfish can cause serious illness. Some species of mold produce aflatoxin . Aspergillus flavus and Aspergillus parasiticus are aflatoxin-producing molds. The toxin is especially a concern when potatoes are contaminated. Ingestion of the contaminated potatoes can cause serious, even fatal illness. Ricin is a toxin that is produced by the castor bean. It is the third most deadly toxin that is known, after the toxins produced by Clostridium botulinum and Clostridium tetani. The symptoms of ricin toxin include nausea, muscle spasms, severe lung damage, and convulsions. These symptoms appear within hours, and, without treatment, death from pulmonary failure can result within three days. There is no vaccine or antidote for ricin toxin. Some toxins that are capable of causing much harm are also a source of protection. Because of its potency, a toxin cannot be used protectively in its unaltered form. Toxins can be altered, however, so that they do not produce the undesirable effects, but still stimulate the immune system to produce antibodies to a critical part of the toxin molecule. The weakened version of a toxin is called a toxoid. The anthrax vaccine that is currently licensed for use contains two toxoids in addition to other immune stimulating molecules. The immune response will produce antibodies to the two toxins of the anthrax bacterium. see also Aflatoxin; Biosensor technologies; Botulinum toxin; Food supply; Pathogens; Thin layer chromatography. |
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"Toxins." World of Forensic Science. 2005. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "Toxins." World of Forensic Science. 2005. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1G2-3448300565.html "Toxins." World of Forensic Science. 2005. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3448300565.html |
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toxin
toxin poison produced by living organisms. Toxins are classified as either exotoxins or endotoxins. Exotoxins are a diverse group of soluble proteins released into the surrounding tissue by living bacterial cells. Exotoxins have specific reaction sites in the host; e.g., tetanus and botulinum exotoxins affect nerve tissue, and streptococcal toxins attack vascular tissue. Plants and animals also produce protein toxins. Some, such as cobra venom, are enzymes that destroy substances in host tissue. Endotoxins are polysaccharide and phospholipid substances found in the cell walls of bacteria that are freed when the cells die and break up. The pathologic effects of endotoxins, similar for all bacterial sources, include fever, shock, and intestinal hemorrhage. In sufficiently low doses toxins stimulate the production of antibodies , or antitoxins , in the host, and toxins of a specific bacterial species have been injected to elicit formation of antibodies against the disease caused by the bacteria. Toxoids are protein toxins that have been heated or chemically treated to deprive them of their toxicity but not of the ability to induce the formation of antibodies. See venom . |
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"toxin." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "toxin." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1E1-toxin.html "toxin." The Columbia Encyclopedia, 6th ed.. 2011. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-toxin.html |
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toxins
toxins A term applied to poisons which are toxic to the human body. Many come from microorganisms — for example, cholera toxin and tetanus toxin are derived respectively from Vibrio cholera and Clostridium tetani. Some toxins are derived from higher organisms — the deadly tetrodotoxin, which blocks nerve conduction, is derived from the liver and ovaries of the puffer fish. Yet others are of fungal origin, such as the liver toxic substance aflatoxin, from a fungus which grows on groundnuts.
Alan W. Cuthbert See immunization; microorganisms; poisons; toxicology. |
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COLIN BLAKEMORE and SHELIA JENNETT. "toxins." The Oxford Companion to the Body. 2001. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. COLIN BLAKEMORE and SHELIA JENNETT. "toxins." The Oxford Companion to the Body. 2001. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O128-toxins.html COLIN BLAKEMORE and SHELIA JENNETT. "toxins." The Oxford Companion to the Body. 2001. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O128-toxins.html |
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toxin
toxin
1. Any poisonous substance of plant or animal origin. 2. A microbial product which is poisonous to animals or plants. The symptoms of many types of human disease are the result of the production of one or more toxins by the pathogen. Toxins usually act at specific sites in the body (e.g. neurotoxins affect nerves, enterotoxins affect the gut). |
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MICHAEL ALLABY. "toxin." A Dictionary of Ecology. 2004. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "toxin." A Dictionary of Ecology. 2004. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O14-toxin.html MICHAEL ALLABY. "toxin." A Dictionary of Ecology. 2004. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O14-toxin.html |
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toxin
toxin
1. Any poisonous substance of plant or animal origin. 2. A microbial product which is poisonous to animals or plants. The symptoms of many types of human disease are due to the production of one or more toxins by the pathogen. Toxins usually act at specific sites in the body (e.g. neurotoxins affect nerves, enterotoxins affect the gut). |
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MICHAEL ALLABY. "toxin." A Dictionary of Zoology. 1999. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "toxin." A Dictionary of Zoology. 1999. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O8-toxin.html MICHAEL ALLABY. "toxin." A Dictionary of Zoology. 1999. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O8-toxin.html |
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toxin
toxin Poisonous substance produced by a living organism. The unpleasant symptoms of many bacterial diseases are due to the release of toxins into the body by bacteria. Many moulds, some larger fungi, and seeds of some higher plants produce toxins. The venom of many snakes contains powerful toxins. See also fungus; snakebite
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"toxin." World Encyclopedia. 2005. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "toxin." World Encyclopedia. 2005. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O142-toxin.html "toxin." World Encyclopedia. 2005. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O142-toxin.html |
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toxin
toxin A poison produced by a living organism, especially a bacterium. An endotoxin is released only when the bacterial cell dies or disintegrates. An exotoxin is secreted by a bacterial cell into the surrounding medium. In the body a toxin acts as an antigen, producing an immune response.
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"toxin." A Dictionary of Biology. 2004. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "toxin." A Dictionary of Biology. 2004. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O6-toxin.html "toxin." A Dictionary of Biology. 2004. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O6-toxin.html |
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toxin
tox·in / ˈtäksin/ • n. an antigenic poison or venom of plant or animal origin, esp. one produced by or derived from microorganisms and causing disease when present at low concentration in the body. |
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"toxin." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "toxin." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O999-toxin.html "toxin." The Oxford Pocket Dictionary of Current English. 2009. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-toxin.html |
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toxin
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"toxin." A Dictionary of Nursing. 2008. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "toxin." A Dictionary of Nursing. 2008. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O62-toxin.html "toxin." A Dictionary of Nursing. 2008. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O62-toxin.html |
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toxin
toxin A microbial product which is poisonous to plants or animals.
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MICHAEL ALLABY. "toxin." A Dictionary of Plant Sciences. 1998. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "toxin." A Dictionary of Plant Sciences. 1998. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O7-toxin.html MICHAEL ALLABY. "toxin." A Dictionary of Plant Sciences. 1998. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O7-toxin.html |
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toxin
toxin
•assassin • Yeltsin • sasine
•Solzhenitsyn • rebbetzin
•biomedicine, medicine
•ceresin
•ricin, Terramycin
•tocsin, toxin
•Wisconsin • oxytocin • niacin
•moccasin • characin • Capuchin
•Latin, satin
•plantain • captain
•marten, martin
•cretin
•pecten, pectin
•Quentin
•clandestine, destine, intestine
•sit-in • quintain • bulletin • chitin
•Austen, Mostyn
•fountain, mountain
•gluten, highfalutin, Rasputin
•Dustin, Justin
•biotin • legatine • gelatin • keratin
•certain, Curtin
•Kirsten • Gethin • lecithin • Bleddyn
•Gavin, ravin, ravine, savin, spavin
•Alvin, Calvin
•Marvin
•Bevin, Kevin, levin, Previn, replevin
•kelvin, Melvin
•riboflavin • covin • Mervyn
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"toxin." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "toxin." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O233-toxin.html "toxin." Oxford Dictionary of Rhymes. 2007. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O233-toxin.html |
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