Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.1.5 (neuropathy target esterase)
 1,070 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two phenyl valerate hydrolyzing carboxylesterases (EC 3.1.1.1) of hen brain were identified as neurotoxic esterases (NTEA and NTEB) by kinetic analysis of organophosphorus inhibition curves. The activities of both NTE isoenzymes with phenyl valerate (PV) as substrate and their inhibition rate constants were determined in six different animals. In-vivo-application of a single oral dose of 500 mg/kg triorthocresyl phosphate (TOCP) caused 86% inhibition of NTEA and 93% inhibition of NTEB within 24 h. Total NTE activity (NTEA plus NTEB) determined by kinetic analysis shows an excellent correlation (r = 0.989) to NTE activity simultaneously tested with a differential NTE assay. The excellent sensitivity (97%) and high specificity (79%) of the NTE differential test is demonstrated.
 ...
PMID:Neurotoxic esterase. Identification of two isoenzymes in hen brain. 661 36

Paraoxon- and mipafox-sensitive phenyl valerate (PV) hydrolases found in chicken nervous tissue were solubilized by Triton X-100 and separated by sucrose density gradient centrifugation. Enzyme activity from chick embryo brain with properties of neurotoxic esterase (NTE, insensitive to 40 microM paraoxon, sensitive to 50 microM mipafox) migrated in a 9S peak.
 ...
PMID:Separation of paraoxon and mipafox sensitive esterases by sucrose density gradient sedimentation. 662 25

The mechanism of delayed neurotoxicity of some OP (organophosphorus) esters such as DFP (di-isopropyl phosphorofluoridate) and TOCP (tri-o-cresyl phosphate) involves an initial two-step process affecting an esterase called NTE (neurotoxic esterase). This understanding permits the assessment of delayed neuropathic potential in terms of a quantitative measurement of inhibition of NTE in tissue taken from dosed hens. Structure/activity relationships have been rationalized and the neurotoxic potential of those OP esters which are direct inhibitors of esterases may now be assessed in vitro. The response of human NTE can usefully be compared with that of hen NTE. Nil delayed neurotoxic potential is associated with carbamate or phosphinate anticholinesterases which may be designed as insecticides.
 ...
PMID:The mechanism of delayed neuropathy caused by some organophosphorus esters: using the understanding to improve safety. 700 90

Rubella virosomes were prepared from performed liposomes and detergent solubilized viral hemagglutinin. The liposomes were made from lecithin/dicetyl phosphate (3.5 : 1) films resuspended in NTE buffer and sonicated. Viral hemagglutinin was prepared from purified virus after solubilization with Triton X-100 and centrifugation through a sucrose gradient containing beta-D-octylglucoside. Electron microscopy of the rate zonal purified virosomes, showed virus-like structures of 40 - 80 nm. The virosomes retained the biological activity of the hemagglutinin and had a buoyant density of 1.2 g/cm3.
 ...
PMID:Rubella virosomes: preparation and ultrastructure. 732 60

Chlorpyrifos (diethyl 3,5,6-trichloro-2-pyridyl phosphorothionate) is a broad-spectrum organophosphorus (OP) insecticide. Anticipated increases in the already extensive use of this compound have prompted this reassessment of its neurotoxicity. Because chlorpyrifos and other OP insecticides are designed to produce acute cholinergic effects through inhibition of acetylcholinesterase (AChE) and some OP compounds can cause OP compound-induced delayed neurotoxicity (OPIDN) via chemical modification of neurotoxic esterase (neuropathy target esterase, NTE), this review focuses on the capacity of chlorpyrifos to precipitate these and other adverse neurological consequences. Chlorpyrifos exhibits only moderate acute toxicity in many mammalian species, due largely to detoxification of the active metabolite, chlorpyrifos oxon, by A-esterases. Rats given large doses of chlorpyrifos (sc in oil) have prolonged inhibition of brain AChE, possibly due to slow release of the parent compound from a depot. Associated cognitive and motor deficits return to normal well before recovery of AChE activity and muscarinic receptor down-regulation, as expected from classic tolerance. Controlled studies of OP compound exposures in humans also indicate that cognitive dysfunction requires substantial AChE inhibition. Information is relatively sparse on neurological dysfunction that is secondary to theoretical reproductive, developmental, or immunological effects, but the best available data indicate that such effects are unlikely to result from exposures to chlorpyrifos. In accord with the much greater inhibitory potency of chlorpyrifos oxon for AChE than for NTE, clinical reports and experimental studies indicate that OPIDN from acute exposures to chlorpyrifos requires doses well in excess of the LD50, even when followed by repeated doses of the OPIDN potentiator phenylmethanesulfonyl fluoride (PMSF). Likewise, studies in hens show that subchronic exposures at the maximum tolerated daily dose do not result in OPIDN. Although exposure to chlorpyrifos as a result of normal use is unlikely to produce classical OPIDN, a recent report stated that mild reversible sensory neuropathy had occurred in eight patients who had been exposed subchronically to unknown amounts of chlorpyrifos. It is not clear whether these cases represent an incorrect linkage of cause and effect, a newly disclosed reversible sensory component of OPIDN, or an entirely new phenomenon. The question of the potential for chlorpyrifos to cause this mild sensory neuropathy could be resolved by the use of quantitative tests of sensory function in animal experiments and/or prospective studies of humans with known exposures to chlorpyrifos.
 ...
PMID:Assessment of the neurotoxic potential of chlorpyrifos relative to other organophosphorus compounds: a critical review of the literature. 753 75

The distribution of binding sites for NTE-biotinyl-[Arg3]-substance P (SPB) was demonstrated in neonatal foreskin using a conjugate of streptavidin with horseradish peroxidase. The observed binding is reversible, and may be abrogated by either the non-peptide substance P receptor antagonist, CP-96,345, or by unlabelled substance P. The generalized epidermal distribution and focal dermal localization of SPB binding suggest that although NK-1 receptors are abundant in human neonatal foreskin, neuromodulatory mechanisms may play a significant role in epidermal physiology.
 ...
PMID:Substance P binding in normal neonatal foreskin. 753 77

A "hen model" or organophosphorus induced delayed neuropathy (OPIDN) has been developed using white leghorn exposed acutely to one of five dosages of tri-ortho-cresyl phosphate (TOCP), between 300 to 700 mg/Kg. Neuropathy target esterase was studied in brain and peripheral nerve 24 and 48 hrs following exposure. Behavioral symptoms abnormality was assessed from days 1 through 20 after exposure using a 7 point rating scale and neuropathological examination was conducted on sample collected from animals on days 0, 7, 14 and 21. Neuropathological abnormalities were indicated by damage scores between 0 (no damage) and 4 (gliosis of brain tissue, myelin loss, appearance of axonal foci etc and more than 55% degeneration of peripheral nerve fibres). TOCP (600 and 700 mg/Kg, orally) was able to inhibit NTE more than 75% in brain and peripheral nerves. TOCP at the same dosage was also capable of resulting maximal levels of neuropathological score at 4. After exposure to doses weight loss was observed abruptly in a greater extent at the beginning leading to a change in weight gain till the end of the experiment. Behavioral signs were also dose dependent. Symptoms (gain abnormality, ataxia, paresis) were noted on the early stage of experiment. Inhibition of NTE was 65% could not be reached in hens given TOCP without causing lethality and no significant ataxia or lesions developed in those birds. Behavioral signs were also observed to be late onset. These data indicate that more than 75% inhibition of peripheral nerve NTE after 24 hr exposure was predictive of severe behavioral abnormalities and pathology in the hen whereas less peripheral NTE inhibition was indicative of less severe behavioral abnormalities and a lower score for neuropathological damage.
 ...
PMID:Biochemical, neuropathological and behavioral studies in hens induced by acute exposure of tri-ortho-cresyl phosphate. 755 52

Inhibition of neuropathy target esterase (NTE, neurotoxic esterase) and acetylcholinesterase (AChE) activities was compared in brain and spinal cords of adult While Leghorn hens and adult male Long Evan rats 4-48 hr after administration of triortho-tolyl phosphate (TOTP po, 50-500 mg/kg to hens; 300-1000 mg/kg to rats), phenyl saligenin phosphate (PSP im 0.1-2.5 mg/kg to hens; 5-24 mg/kg to rats), mipafox (3-30 mg/kg ip to hens and rats), diisopropyl phosphorofluoridate (DFP sc, 0.25-1.0 mg/kg to hens; 1-3 mg/kg to rats), dichlorvos (5-60 mg/kg ip to hens; 600-2000 mg/kg to rats), and carbaryl (300-560 mg/kg ip to hens; 30-170 mg/kg to rats). Inhibitions of NTE and AChE were dose-related after administration of all compounds to both species. Hens and rats given TOTP, PSP, mipafox, and DFP demonstrated delayed neuropathy 3 weeks later, with spinal cord lesions and clinical signs more notable in hens. Ratios of NTE/AChE inhibition in hen spinal cord, averaged over the doses used, were 2.6 after TOTP, 5.2 after PSP, 1.3 after mipafox, and 0.9 after DFP, which contrast with 0.53 after dichlorvos, 1.0 after malathion, and 0.46 after carbaryl. Rat NTE/AChE inhibition ratios were 0.9 after TOTP, 2.6 after PSP, 1.0 after mipafox, 0.62 after DFP, 1.3 after dichlorvos, 2.2 after malathion, and 1.1 after carbaryl. The lower NTE/AChE ratios in rats given dosages of the four organophosphorus compounds that caused delayed neuropathy interferred with survival, an effect that was not a problem in hens.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Comparison of the relative inhibition of acetylcholinesterase and neuropathy target esterase in rats and hens given cholinesterase inhibitors. 771 47

Certain organophosphorus compounds (OPs) produce a delayed neuropathy (OPIDN) in man and some animal species. Capability to cause OPIDN is generally predicted in animal models by early and irreversible inhibition of neuropathy target esterase (NTE, neurotoxic esterase). In this study, NTE inhibition in response to OP exposure was examined in cell culture, using the human SH-SY5Y neuroblastoma cell line. Cells were exposed for 1 hr to equimolar (1 x 10(-5) M) concentrations of 6 OPs associated with OPIDN in vivo (including 2 protoxicants and 4 active (-P = O) toxicants), and 8 OPs that do not produce delayed neuropathy in animal models (including 5 protoxicants and 3 -P = O compounds). The -P = O compounds that cause OPIDN in animal models inhibited NTE > 60% at the test concentration; -P = O compounds that do not cause OPIDN in animal models inhibited NTE < 30%. Protoxicants did not inhibit NTE at the test concentration, reflecting their limited metabolism in the human cell line. These results indicate that human neuroblastoma cells have potential use in the initial screening of bioactive OPs with capability for causing OPIDN.
 ...
PMID:Neuropathy target esterase inhibition by organophosphorus esters in human neuroblastoma cells. 799 Dec 19

A neuroblastoma cell line of human origin was used as an in vitro model system to examine early effects on inhibition of neuropathy target esterase (NTE, also known as neurotoxic esterase) in the presence of agents belonging to classes of chemicals previously demonstrated to modify organophosphorus-induced delayed neuropathy in hens. For this study, differentiated SY-5Y cells were treated for up to 10 min with mipafox, an organophosphorus compound, and NTE inhibition was determined when cells exposed to mipafox were also exposed to the carbamate, aldicarb, and to the calcium channel blocker, verapamil. Cells were exposed to aldicarb or verapamil 5 min before, at the same time, or 2 min after mipafox. Less NTE inhibition was observed when either aldicarb or verapamil was included in the incubation of SY-5Y cells with mipafox. Effects of aldicarb and verapamil on NTE inhibition in differentiated SY-5Y cells were similar to effects in chicken brain homogenates. These results indicate that NTE inhibition can be detected in neuroblastoma cells, that these cells respond in a manner similar to chicken brain, and that mipafox-induced inhibition of NTE can be decreased in the presence of aldicarb or verapamil.
 ...
PMID:Modification of mipafox-induced inhibition of neuropathy target esterase in neuroblastoma cells of human origin. 833 99


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>