Botulinum toxin, or botulinum neurotoxin (commonly called botox), is a highly potent neurotoxic protein produced by the bacterium Clostridium botulinum and related species. It prevents the release of the neurotransmitter acetylcholine from axon endings at the neuromuscular junction, thus causing flaccid paralysis. The toxin causes the disease botulism. The toxin is also used commercially for medical and cosmetic purposes. Botulinum toxin is an acetylcholine release inhibitor and a neuromuscular blocking agent.
The seven main types of botulinum toxin are named types A to G (A, B, C1, C2, D, E, F and G).New types are occasionally found. Types A and B are capable of causing disease in humans, and are also used commercially and medically. Types C–G are less common; types E and F can cause disease in humans, while the other types cause disease in other animals.
Botulinum toxins are among the most potent toxins known to science. Intoxication can occur naturally as a result of either wound or intestinal infection or by ingesting formed toxin in food. The estimated human median lethal dose of type A toxin is 1.3–2.1 ng/kg intravenously or intramuscularly, 10–13 ng/kg when inhaled, or 1000 ng/kg when taken by mouth.
Uses
Botulinum toxin uses includes medicinal (e.g., treatment of spastic conditions, hyperhidrosis), cosmetic (removal of wrinkles), or as a potential terrorism agent (e.g., via aerosolization).
Clinical Use
Botulinum toxin is used clinically in the treatment of blepharospasm, writer’s cramp, spasticities of various origins, and rigidity due to extrapyramidal disorders. It is also used to treat gustatory sweating and cosmetically to decrease facial wrinkles. Botulinum toxin A (Botox, Oculinum) injected intramuscularly produces functional denervation that lasts about 3 months. Clinical benefit is seen within 1 to 3 days.Adverse effects range from diplopia and irritation with blepharospasm to muscle weakness with dystonias.
Side effects botulinum toxin injection is the most toxic substance known. One gram of crystalline toxin adequately dispersed can kill a population of a million people, so its use in bioterrorism is a possibility. The toxin can be introduced through inhalation or ingestion but not through dermal exposure. The threat of mass inhalation poisoning is limited by the ability or inability to aerosolize the toxin for widespread dispersion. Contaminating the water or food supply is also a possibility, although the toxin is degraded by standard water treatment and by heating of foods to 85°C (185°F) for 5 minutes. Prior immunization with toxoid vaccine is advisable for personnel at risk, but prophylactic administration of trivalent equine antitoxin is not recommended.
Toxicity evaluation
Inadequately sterilized processed products (e.g., canned foods) can be contaminated with neurotoxin-producing spores, leading to potential accidental exposure by ingestion (the most common route). Poor food hygiene during food preparation has been the major causes of large outbreaks of foodborne botulism. In patients with underdeveloped intrinsic gut immunity (e.g., infants), C. botulinum colonization of the gastrointestinal tract can occur. Susceptibility to colonization can also occur where the normal gastrointestinal protective mechanisms are deficient (e.g., in patients who have undergone major gastric surgery whereby acid production is reduced or where bile acid formation has ceased).
Cutaneous absorption and thus toxicity do not occur if the skin is undamaged. However, an open wound or mucous membrane exposed to the bacterium increases the risk of toxicity.
More Introduction:https://en.wikipedia.org/wiki/Botulinum_toxin
