Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.1.8 (cholinesterase)
 12,691 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cholinesterase activities in the hearts and ganglia of an oyster (Crassostrea virginica) and a venerid clam (Macrocallista nimbosa) were measured and compared. Tissue extracts were partially purified by ammonium sulfate fractionation followed by gel column chromatography. Enzymatic activity was assayed spectrophotometrically; substrates were acetyl-, butyryl-, and propionylthiocholine (ATC, BTC, PTC). Kinetic constants characterizing each enzyme were derived. At all substrate concentrations, the hydrolysis rates of both clam enzymes were in the order: BTC greater than PTC greater than ATC. With oyster enzymes the ranking was ATC greater than or equal to PTC greater BTC. The specific activities of oyster heart and ganglion enzymes were similar. In contrast, clam ganglion extracts were 75-100 times more active than clam heart extracts and, with any substrate, had greater activity than either oyster enzyme. All enzyme preparations proved to be homogeneous on the bases of constant substrate activity ratios in successive column fractions, and of intermediate velocities with mixed substrates. Six cholinesterase inhibitors were tested. The specific acetylcholinesterase antagonist, B.W. 62C47, WAS MUCH MORE EFFECTIVE AGAINST OYSTER ENZYMES, WHILE THE SPECIFIC ANTIBUTYRYLCHOLINESTERASE, ISO-OMPA, almost totally inhibited calm enzyme activity, but had little effect on oyster. Eserine was the most effective inhibitor of both enzymes. In conclusion, the enzymes in oyster tissues are acetylcholinesterases, while clam enzymes are butyrylcholinesterases. Nevertheless, clam ganglion esterase is sifficiently active to hydrolyze the physiological substrate, acetylcholine. These results explain the long-observed differences in isolated heart pharmacology between ostreid and venerid bivalves.
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PMID:A comparison of the cholinesterases of an oyster (Crassostrea virginica) and a clam (Macrocallista nimbosa). 1 Mar 39

D(-)S-and L(+)R-tropinoylcholines were synthesized and their antagonisms to acetylcholine (ACh) were studied at muscarinic receptors (guinea-pig longitudinal ileal muscle), acetylcholinesterase (AChE) and pseudocholinesterase (ChE). Tropinoylcholines were reversible competitive antagonists at muscarinic receptors. D(-)S-tropinoylcholine exhibited a higher affinity as an antagonist at muscarinic receptors than the L(+)R-isomer. ONE MOLECULE OF THE ANTAGONIST COMPETES WITH ONE MOLECULE OF THE AGONIST AT EACH MUSCARINIC RECEPTOR SITE. Tropinoylcholines were competitive inhibitors of AChE. L(+)R-tropinoylcholine exhibited a lower K1 and a higher affinity for AChE. Therefore, muscarinic receptors were stereospecific for the D-configuration, whereas AChE was stereospecific forthe L-configuration of tropinoylcholine. Tropinoylcholines were week agonist at nicotinic receptors (frog rectus abdominis); they were substrates of ChE at low concentrations, but they inhibited ChE partially at high concentrations. L(+)R-tropinoylcholine had a lower apparent Km and a higher affinity than its isomer. Therefore, the esteratic site of ChE is possible stereospecific for the L-configuration of tropinoylcholine. Both tropinoylcholines were mixed inhibitors (competitive and noncompetitive) of ACh hydrolysis by ChE. The results imply that the tropinoylcholines interact at a second site as well as the esteratic site.
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PMID:Relationships between the chemical structure and pharmacological activities of D(-)S-and L(+)R-tropinoylcholines at cholinergic sites. 30 65

After careful laboratory evaluation every new insecticide is subjected to village-scale trials, under the WHO Scheme for Evaluating and Testing New Insecticides, before it can be recommended for general use. Several such trials have been conducted to obtain both entomological and toxicological information. The toxicological assessment includes both clinical observations and laboratory tests on both spray-men and residents.Laboratory tests should be of a kind suitable for field operations. So far only serum cholinesterase determinations have proved suitable: determinations are usually made before spraying, immediately after spraying, and again a few weeks later.THE FINAL EVALUATION OF THE SAFETY OF A NEW INSECTICIDE MUST ALWAYS TAKE INTO ACCOUNT THE CONDITIONS UNDER WHICH IT IS LIKELY TO BE USED: it must be remembered that it will be used in confined spaces, that it may contaminate bedding and food, that safety precautions by the spray-men will be negligible, and that the general supervision will be inadequate.
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PMID:Experience in the WHO field programme for evaluating the safety of new insecticides. 531 48

THE MAJOR THERAPEUTIC TRENDS: The treatment of psychosis in late life depends on the etiology of the delusion but also on its behavioral consequences (agitation, aggressiveness). We distinguish between the treatment of long term old psychosis and delusions occurring late in life (after the age of 60). FOR THE OLD PSYCHOSES: The reduction in the symptomatology often permits a reduction in the doses and the relay to atypical neuroleptics with improved tolerance. FOR DELUSIONS OCCURRING LATE IN LIFE: The treatment will be adjusted to the etiology of the delusion: delirious states associated with dementia, thymus delusion, schizophrenic or non-schizophrenic psychosis, delusion related to cerebral-vascular disorders or to sensorial dysafferentation. One should note that emotional and delusional disorders are often concomitant in the elderly. THE TWO TREATMENT AXES: The first therapeutic element is non-pharmacological: reassurance or even brief psychotherapy, family counseling and prevention of enhancing, notably environmental, factors. The pharmacological element preferably includes atypical anti-psychotics, antidepressants in some cases together with anti-epileptics in cases of concomitant rebellious aggressiveness. In cases of dementia with cholinergic deficiency (Alzheimer, Lewy body dementia, mixed dementia) cholinesterase inhibitors have demonstrated their efficacy on the hallucinations. Advice for a pertinent strategy of action should be provided.
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PMID:[Delirious states in elderly persons. Therapeutic modalities]. 1285 35