Botulinus toxin

Botulinus toxin comes from Clostridium botulmum, an organism that causes food poisoning. Botulinus toxin prevents the release of ACh from nerve endings by mechanisms that are not clear. Death occurs from respiratory failure caused by the inability of diaphragm muscles to contract. 

The term microbial toxin is usually reserved by microbiologists for toxic substances produced by microorganisms that are of high molecular weight and have antigenic properties toxic compounds produced by bacteria that do not fit these criteria are referred to simply as poisons. Many of the former are proteins or mucoproteins and may have a variety of enzymatic properties. They include some of the most toxic substances known, such as tetanus toxin, botulinus toxin, and diphtheria toxin. Bacterial toxins may be extremely toxic to mammals and may affect a variety of organ systems, including the nervous system and the cardiovascular system. A detailed account of their chemical nature and mode of action is beyond the scope of this volume. 

Note Many drugs and toxins block neuromuscular transmission by other mechanisms, such as interference with the synthesis or release of acetylcholine, but most of these agents are not employed clinically for this purpose. One exception is botulinus toxin, which has been administered locally into muscles of the orbit in the management of blepharospasm and strabismus. This treatment produces a long-lasting interruption of neuromuscular transmission and reduction of spasmodic ocular movements. Another exception is dantrolene, which blocks release of Ca2+ from the sarcoplasmic reticulum and is used in the treatment of malignant hyperthermia. 

Botulinus toxin from Clostridium botuli-num is the most potent poison known. The estimated lethal dose for 50% of an exposed human population is 1 / 10 9 g/kg (i.e., about 75 nanograms for an adult individual). The toxin, a zinc endopeptidase, blocks exo-cytosis of ACh in motor (and also parasympathetic) nerve endings. Death is caused by paralysis of respiratory muscles. 

Dutton, J.J. and Fowler, A.M. 2007. Botulinum toxin in ophthalmology. Surv. Ophthalmol. 52 13-31. Edmunds, C.W. and Keiper, Jr., G.F. 1924. Further studies on the action of botulinus toxin. JAMA,... 

Several species of Clostridia are able to produce botulinum toxins. These have been divided into groups with distinct physiological properties although a particular botulinum toxin type can be produced by more than one group. However, it has been found that botulinus toxin can be produced by C. botulinum strains which are clearly distinct from the hitherto defined species and are related to different species such as C. butyricum and C. baratii which have... 

Finally botulinus toxins have become enormously useful tools for scientists attempting to characterise the functions of the presynaptic neuronal proteins which bind the toxins and to... 

Guyton, A.C. and MacDonald, A., Physiology of botulinus toxin. Arch. Neurol Psych., 57, 578, 1947. 

The poisoning produced by B. botulinus is the result of action of thiB organism on food. This poison is called the B. botulinus toxin. 

The lethal doses of the various very toxic compounds can vary over a wide range the LD50 value of the well-known Seveso poison 2,3,7,8-tetrachloro-di-benzo-dioxin (TCDD) indicates higher toxicity than potassium cyanide by a factor of 10 000, but it is less toxic than botulinus toxin by nearly the same factor. 

Botulinus toxin 0.000 000 03 Meat, sausage, tinned food... 

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