Esterase inhibition

Choline, 413, 773 Choline-esterase, 262 Choline-esterases, inhibition by... 

Organophosphate Ester Hydraulic Fluids. In a study of nonspecific monocyte esterase staining, humans who were exposed to aryl phosphates occupationally showed very slight esterase inhibition (Mandel et al. 1959). 

Padilla S, Veronesi B. 1985. The relationship between neurological damage and neurotoxic esterase inhibition in rats acutely exposed to tri-ortho-cresyl phosphate. Toxicol Appl Pharmacol 78 78-87. 

Lord and Potter1 have claimed that it is important not to generalize the known anti-cholinesterase activity of organo-phosphorus insecticides in mammals to account for their action in insects. They could find no specific cholinesterase in two species of insect, but there was a general esterase inhibited by the insecticides. 

G. Gianutsos, S. D. Cohen, G. Carlson, R. Heyman, P. Salva, G. Morrow, G. J. Hite, Alteration of in vivo and in vitro Effects of Heroin by Esterase Inhibition , Toxicol. Appl. Pharmacol. 1986, 82, 14-18. 

White RD, Earnest DL, Carter DE The effect of intestinal esterase inhibition on the in vivo absorption and toxicity of di- -butyl phthalate. Food Chem Toxicol 21 99-101, 1983... 

Assays of acetyl- and butyrylcholine esterases inhibition, as well as of modulation of calcium channels and nicotinic receptors have been conducted in vivo. Moreover, their interaction with the active center of acetylcholine esterase has been simulated by molecular dynamics. For synthesized compounds the IC50 of acetylcholine esterase inhibition was about 9 X M, and for the most active the value was four to five times... 

Wilson, I.B, 1955. Reactivation of human-serum esterase inhibited by alkylphosphates. J. Am. Chem. Soc. 77 2383-2386. 

Large cations have a powerful effect on neuromuscular transmission, resulting from acetylcholine esterase inhibition and curariform activity. Examples are quaternary nitrogen, phosphorus and arsenic bases and chelate species such as the tris-(2,2 -bipyridine)iron(II) cation when it is injected intravenously. Bis(2,2, 2"-terpyri-dine)ruthenium(Il) perchlorate has about one tenth of the activity of curare182). 

S. capricornutum ASPAb MICRO-CRUSTACEAN ERA Esterase inhibition WT 24 h IC50 3 Blaise Menard, 1998... 

Acute exposure Short period of exposure (minutes, hours, or a few days) relative to the life span of the organism (usually set at < 10% of an organism s life span). See also Acute effect and Acute toxicity. Volume 1(1,2,3,5,10), Volume 2(5,8,11). For Selenastrum capricornutum, whose cell numbers double every 12 h at 24°C, a contact time of 1-4 h with a test sample would correspond to an acute exposure allowing for the determination of corresponding acute toxicity effects. Measuring esterase inhibition in S. capricornutum after a 1-h exposure to a test chemical is another example of an acute exposure toxicity bioassay (Snell et al., 1996). Volume 1(3). 

Snell, T., Mitchell, J.L. and Burbank, S.E. (1996) Rapid toxicity assessment with microalgae using in vivo esterase inhibition, in G.K. Ostrander (Ed.), CRC Press/Lewis Publishers, Boca Raton, Florida, U.S.A., pp. 13-22. 

Starting from the commercially available 3,6-dichloropyridazine, 3-amino-6-arylpyridazines, which show acetylcholine esterase inhibiting activities, were prepared in good yields under mild conditions by means of a Suzuki coupling (Eq. (40)) [71]. 

The inhibition by other organophosphate compounds of the carboxylesterase which hydrolyzes malathion is a further example of xenobiotic interaction resulting from irreversible inhibition because, in this case, the enzyme is phosphorylated by the inhibitor. A second type of inhibition involving organophosphorus insecticides involves those containing the P=S moiety. During CYP activation to the esterase-inhibiting oxon, reactive sulfur is released that inhibits CYP isoforms by an irreversible interaction with the heme iron. As a result, these chemicals are inhibitors of the metabolism of other xenobiotics, such as carbaryl and fipronil, and are potent inhibitors of the metabolism of steroid hormones such as testosterone and estradiol. 

TABLE 50.3. Catalytic constants for hydrolysis of nerve agents and rate constants of esterase inhibition... 

Davis, S.L., Tanaka, D., Jr., Aulerich, R.J., Bursian, S.J. (1999). Organophosphorus-induced neurotoxicity in the absence of neuropathy target esterase inhibition the effects of triphenyl phosphine in the European ferret. Toxicol. Sci. 49 78-85. 

Alberts, P. (1990). A new H-oxime restores rat diaphragm contractility after esterase inhibition in vitro. Eur. J. Pharmacol. 184 191. ... 

Techniques. In 1962, McKinley and Read (42) developed an esterase-inhibition technique for the detection of organophosphate pesticide residues on paper chromatograms. The procedure involved conversion of the thiophosphates with bromine to yield active esterase inhibitors, the inhibition by the pesticide of the esterases from a beef liver homogenate sprayed onto the chromatogram, the hydrolysis of the substrate (a-naph-thyl acetate) which was sprayed onto the paper after the liver homogenate had dried, and the development of a background color between Fast Blue RR and the hydrolysis product, a-naphthol. 

Ehrich M, Correll L, Veronesi B. Acetylcholinesterase and neuropathy target esterase inhibitions in neuroblastoma cells to distinguish organophosphorus compounds causing acute and delayed neurotoxicity. Fund Appl Toxicol. 1997 38 55-63. 

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