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Showing papers by "Ministry of Supply published in 2011"


Journal ArticleDOI
D. R. Davies1
TL;DR: Progress has been so rapid during the last 2 years that yet another review is justified, and several new organo-phosphorus compounds have been synthesised, which have proved to be powerful physiological and biochemical tools.
Abstract: ALTHOUGH several reviews upon the role of cholinesterase, acetylcholine and anticholinesterase drugs have been written since 1945 (Feldbergl, Bodansky2, Aug~stinsonn~, Koelle and Gilman4, Whittakers, Holmsteads and Nachmansohn and Wilson7), progress has been so rapid during the last 2 years that yet another review is justified. The reasons for the great interest in this field are two-fold; first the results which are emerging are helping to explain the process of neuro-muscular transmission ; secondly, during the last few years, several new organo-phosphorus compounds have been synthesised, which have proved to be powerful physiological and biochemical tools, and in addition, many of them have been shown to be valuable insecticides which are being extensively used in agriculture. Since many of these compounds are highly toxic to man, their safe use has given rise to a number of problems which have had to be solved in order that the full advantages of these materials could be exploited. The following account is therefore a summary of progress mainly during the last 2 or 3 years. Cholinesterase is the enzyme which hydrolyses acetylcholine. Inasmuch as cholinesterase is recognised by its action on acetylcholine in vitro, at least two separate enzymes have been described previously, which satisfy th is condition. The “true” cholinesterase, known also as the “specific” enzyme, is generally found in nervous tissues and the red cells of most mammalian species. This enzyme, it is generally agreed, destroys acetylcholine at nerve endings. The pseudo enzyme, also known as the non-specific cholinesterase, is found in human serum (usually associated with the IV globulin fraction of Cohn), white matter of nervous tissue and dog’s pancreas. No specific function has been found for this enzyme, neither has any naturally occurring substrate been demonstrated. Indeed, many workers believe that acetylcholine, in vivo, is not normally hydrolysed by the pseudo esterase. These enzymes exhibit different kinetic properties (Alles and Hawe@, Mendel, Mundel and Rudneyg, Augu~tinsonn~). They are differently distributed in tissues (Augu~tinsonn~, Orde and ThompsonloJl) and may be differentially inhibited by various inhibitors (Mazur and Bodansky12, Hawkins and MendeP3, Adams and Thompson1*, Todrick15, Austin and Berry16 and Aldridgel’). They also exhibit different specificity patterns towards choline esters (Nachmansohn and Rothenbergla, Mendel et d9, Adamslg, Adams and Whittaker20, Mounter and Whittaker21, Sturge and Whittaker22). Thus, true cholinesterase, i.e., the enzyme present in the grey matter and erythrocytes of many species, hydrolyses acetylcholine

21 citations