Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.1.5 (neuropathy target esterase)
1,070 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Certain esterase inhibitors, such as carbamates, phosphinates and sulfonyl halides, do not cause neuropathy as some organophosphates, but they may exacerbate chemical or traumatic insults to axons. This phenomenon is called promotion of axonopathies. Given the biochemical and toxicological characteristics of these compounds, the hypothesis was made that the target of promotion is a phenyl valerate (PV) esterase similar to neuropathy target esterase (NTE), the target of organophosphate induced delayed polyneuropathy. However, attempts to identify a PV esterase in hen peripheral nerve have been, so far, unsuccessful. We tested several esters, other than PV, as substrates of esterases from crude homogenate of the hen peripheral nerve. The ideal substrate should be poorly hydrolysed by NTE but extensively by enzyme(s) that are insensitive to non-promoters, such as mipafox, and sensitive to promoters, such as phenyl methane sulfonyl fluoride (PMSF). When phenyl benzoate (PB) was used as substrate, about 65% of total activity was resistant to the non-promoter mipafox (up to 0.5 mM, 20 min, pH 8.0), that inhibits NTE and other esterases. More than 90% of this resistant activity was sensitive to the classical promoter PMSF (1 mM, 20 min, pH 8.0) with an IC(50) of about 0.08 mM (20 min, pH 8.0). On the contrary, the non-promoter p-toluene sulfonyl fluoride caused only about 10% inhibition at 0.5 mM. Several esterase inhibitors including, paraoxon, phenyl benzyl carbamate, di-n-butyl dichlorovinyl phosphate and di-isopropyl fluorophosphate, were tested both in vitro and in vivo for inhibition of this PB activity. Mipafox-resistant PMSF-sensitive PB esterase activity(ies) was inhibited by promoters but not by non promoters and neuropathic compounds.
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PMID:The search of the target of promotion: Phenylbenzoate esterase activities in hen peripheral nerve. 1720 28

Organophosphates (OPs) that inhibit neuropathy target esterase (NTE) with subsequent ageing can produce OP-induced delayed neuropathy (OPIDN). NTE inhibition in lymphocytes can be used as a biomarker of exposure to neuropathic OPs. An electrochemical method was developed to assay NTE in whole blood. The high sensitivity of the tyrosinase carbon-paste biosensors for the phenol produced by hydrolysis of the substrate, phenyl valerate, allowed NTE activity to be measured in diluted samples of whole blood, which cannot be done using the standard colorimetric assay. The biosensor was used to establish correlations of NTE inhibitions in blood with that in lymphocytes and brain after dosing hens with a neuropathic OP. The results of further studies demonstrated that whole blood NTE is a reliable biomarker of neuropathic OPs for up to 96 hours after exposure. These validation results suggest that the biosensor NTE assay for whole blood could be developed to measure human exposure to neuropathic OPs as a predictor of OPIDN. The small blood volume required (100 microL), simplicity of sample preparation and rapid analysis times indicate that the biosensor should be useful in biomonitoring and epidemiological studies. The present paper is an overview of our previous and ongoing work in this area.
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PMID:Biosensor assay of neuropathy target esterase in whole blood as a new approach to OPIDN risk assessment: review of progress. 1761 8

Brain neuropathy target esterase (NTE), associated with organophosphorus (OP)-induced delayed neuropathy, has the same OP inhibitor sensitivity and specificity profiles assayed in the classical way (paraoxon-resistant, mipafox-sensitive hydrolysis of phenyl valerate) or with lysophosphatidylcholine (LysoPC) as the substrate. Extending our earlier observation with mice, we now examine human erythrocyte, lymphocyte, and brain LysoPC hydrolases as possible sensitive targets for OP delayed neurotoxicants and insecticides. Inhibitor profiling of human erythrocytes and lymphocytes gave the surprising result of essentially the same pattern as with brain. Human erythrocyte LysoPC hydrolases are highly sensitive to OP delayed neurotoxicants, with in vitro IC50 values of 0.13-85 nM for longer alkyl analogs, and poorly sensitive to the current OP insecticides. In agricultural workers, erythrocyte LysoPC hydrolyzing activities are similar for newborn children and their mothers and do not vary with paraoxonase status but have high intersample variation that limits their use as a biomarker. Mouse erythrocyte LysoPC hydrolase activity is also of low sensitivity in vitro and in vivo to the OP insecticides whereas the delayed neurotoxicant ethyl n-octylphosphonyl fluoride inhibits activity in vivo at 1-3 mg/kg. Overall, inhibition of blood LysoPC hydrolases is as good as inhibition of brain NTE as a predictor of OP inducers of delayed neuropathy. NTE and lysophospholipases (LysoPLAs) both hydrolyze LysoPC, yet they are in distinct enzyme families with no sequence homology and very different catalytic sites. The relative contributions of NTE and LysoPLAs to LysoPC hydrolysis and clearance from erythrocytes, lymphocytes, and brain remain to be defined.
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PMID:Lysophosphatidylcholine hydrolases of human erythrocytes, lymphocytes, and brain: sensitive targets of conserved specificity for organophosphorus delayed neurotoxicants. 1766 17

In mice, lysophosphatidylcholine (LPC) was found to be a physiological substrate of neuropathy target esterase, which is also bound by organophosphates that cause a delayed neuropathy in human and some animals. However, the mechanism responsible for causing the different symptoms in mice and humans that are exposed to neuropathic organophosphates still remains unknown. In the present study, we examined and compared the effect of exogenous LPC on intracellular Ca(2+) overload in mouse N2a and human SH-SY5Y neuroblastoma cells. LPC caused an intracellular Ca(2+) level ([Ca(2+)](i)) increase in both N2a and SH-SY5Y cells; moreover, the amplitude was higher in N2a cells than that in SH-SY5Y cells. Preincubation of the cells with verapamil, an L-type Ca(2+) channel blocker, did not affect the LPC-induced Ca(2+) increase in N2a cells, verapamil inhibited the response by 23% in SH-SY5Y cells. In Ca(2+)-free medium, LPC produced a significant [Ca(2+)](i) decrease in N2a cells, while it caused 64% of total [Ca(2+)](i) increase in SH-SY5Y cells. The results of a cell viability test suggest that N2a cells were more sensitive to LPC than were SH-SY5Y cells. These data suggested that the LPC-induced [Ca(2+)](i) increase was produced in each cell line through different mechanisms. In particular, the [Ca(2+)](i) increase occurred via entry through a permeabilized membrane in N2a cells, but through L-type Ca(2+) channels as well as by Ca(2+) release from intracellular Ca(2+) stores in SH-SY5Y cells. Thus, the symptomatic differences of organophosphate-induced neurotoxicity between mice and humans are probably not related to the diverse amplitudes of intracellular Ca(2+) overload produced by LPC. Moreover, the demyelination effect induced by LPC in mice may be a consequence of its detergent effect on membranes.
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PMID:Different mechanisms of lysophosphatidylcholine-induced Ca(2+) mobilization in N2a mouse and SH-SY5Y human neuroblastoma cells. 1770 81

The possibility that organophosphorus (OP) compounds contribute to motor neuron disease (MND) is supported by association of paraoxonase 1 polymorphisms with amyotrophic lateral sclerosis (ALS) and the occurrence of MND in OP compound-induced delayed neuropathy (OPIDN), in which neuropathy target esterase (NTE) is inhibited by organophosphorylation. We evaluated a consanguineous kindred and a genetically unrelated nonconsanguineous kindred in which affected subjects exhibited progressive spastic paraplegia and distal muscle wasting. Affected subjects resembled those with OPIDN and those with Troyer Syndrome due to SPG20/spartin gene mutation (excluded by genetic linkage and SPG20/spartin sequence analysis). Genome-wide analysis suggested linkage to a 22 cM homozygous locus (D19S565 to D19S884, maximum multipoint LOD score 3.28) on chromosome 19p13 to which NTE had been mapped (GenBank AJ004832). NTE was a candidate because of its role in OPIDN and the similarity of our patients to those with OPIDN. Affected subjects in the consanguineous kindred were homozygous for disease-specific NTE mutation c.3034A-->G that disrupted an interspecies conserved residue (M1012V) in NTE's catalytic domain. Affected subjects in the nonconsanguineous family were compound heterozygotes: one allele had c.2669G-->A mutation, which disrupts an interspecies conserved residue in NTE's catalytic domain (R890H), and the other allele had an insertion (c.2946_2947insCAGC) causing frameshift and protein truncation (p.S982fs1019). Disease-specific, nonconserved NTE mutations in unrelated MND patients indicates NTE's importance in maintaining axonal integrity, raises the possibility that NTE pathway disturbances contribute to other MNDs including ALS, and supports the role of NTE abnormalities in axonopathy produced by neuropathic OP compounds.
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PMID:Neuropathy target esterase gene mutations cause motor neuron disease. 1831 24

To examine the efficacy of calcium gluconate (two doses of Ca-Glu 5 mg/kg i.v.) to alleviate the injurious effects of organophosphorus induced delayed neuropathy (OPIDN) in the presence or absence of phenylmethanesulfonyl fluoride (PMSF 90 mg/kg i.m.), 14 groups of four isabrown hens were used. To measure the lymphocyte neuropathy target esterase (LNTE)activity, groups receiving just distilled water (control), groups receiving just Tri-orto-cresyl phosphate (TOCP; 500 mg/kg p.o.) (Positive control), and other groups receiving TOCP and Ca-Glu or PMSF simultaneously or 12 hours later following intoxication by TOCP were used. They were sacrificed 12 and 24 hours after the administration of TOCP. To observe a 28-day time course of neurotoxicity scores and calcium plasma concentration, five groups were used. Regarding free Ca(2+)in the plasma, the positive control produced a characteristic profile time course up and down during 28 days, and some hens with maximum score of neurotoxicity in 28 days. The treatment, which prevented greater oscillation in free Ca(2+) in the plasma, presented a decrease in OPIDN in relation to the positive control. Twelve hours after the administration of TOCP, LNTE was 70-80% inhibited when compared with control, whereas the first decrease in the free Ca(2+) in the plasma was significantly different from the control only 24 hours after the administration of TOCP. In summary, the sooner the Ca-Glu is started, the less severe the neuropathy effects.
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PMID:Effects of calcium gluconate and PMSF in the treatment of acute intoxication of chicken by TOCP. 1865 Feb 57

The neuropathy target esterase is a membrane-bound enzyme linked to organophosphate-induced distal neuropathy. Here we report a tentative mechanism of its solubilization from chicken embryo brains by using phospholipase A2. The enzyme was released from brain membranes after degradation of their structural phospholipids initiated by phospholipase A2. L-A inverted exclamation mark-lysophosphatidylcholine, tested as a representative product of phospholipid hydrolysis, was identified as a new efficient detergent for solubilization of the neuropathy target esterase.
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PMID:A tentative mechanism of solubilization of neuropathy target esterase from chicken embryo brain by phospholipase A2. 1866 Oct 50

The motor neuron diseases (MNDs) are a group of related neurodegenerative diseases that cause the relative selective progressive death of motor neurons. Exploring the molecular mechanisms underlying MND phenotypes has been hampered by their multifactorial nature and high incidence of sporadic cases, although genetic factors are considered to play a considerable role at present. However, environmental factors, especial exposure to neurotoxic substances, could induce neurotoxicity with the same phenotypes of specific MNDs. Organophosphate-induced delayed neuropathy (OPIDN) is a neurodegenerative disorder characterized by ataxia and progression to paralysis, with a concomitant distal axonal degeneration and secondary demyelination of central and peripheral axons. The inhibition and subsequent aging of neuropathy target esterase (NTE) by organophosphate has been proposed to be the initiating event in OPIDN. NTE is characterized to be a lysophospholipase/phospholipase B mostly in the nervous system to regulate phospholipid homeostasis. Brain-specific deletion of mouse NTE contributes to the behavioral defects characterized by neuronal loss. Recently, mutations in human NTE have also been shown to cause a hereditary spastic paraplegia called NTE-related motor neuron disorder with the same characteristics of OPIDN, which supported the role of NTE abnormalities in OPIDN, and raised the possibility that NTE pathway disturbances contribute to other MNDs. Together with the identified association of paraoxonase polymorphisms with amyotrophic lateral sclerosis, there is a possibility that neurotoxic substances contribute to MND in genetically vulnerable people by gene-environment interactions.
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PMID:Motor neuron diseases and neurotoxic substances: a possible link? 1949 9

Organophosphates (OP) are widely used chemicals in agriculture and industry. Some OPs produce a delayed type of neuropathy affecting human and animals following exposure. Subacute neurotoxic doses of some OPs can be potentiated by concomitant exposure to certain chemicals. Lasalocid is a polyether carboxylic ionophore used as a growth promotant and anti-coccidial in the cattle and poultry industries, respectively. Lasalocid is also known to induce peripheral neuropathy. Neurotoxicity of phenyl saligenin phosphate (PSP) and lasalocid and possible interaction were studied in chickens by evaluating motor nerve conduction velocity (MNCV), clinical ataxia, and neuropathy target esterase (NTE) enzyme activity. Forty-eight fryer chickens were divided into four groups as follows: Group 1 (control), group 2 was injected with single subcutaneous (s.c.) PSP (5 mg/kg), group 3 received oral lasalocid sodium (20 mg/kg, b.i.d., for 2 days), and group 4 received single s.c. PSP injection plus oral lasalocid sodium. MNCVs were decreased in groups 2, 3, and 4 compared to control. While there was no difference in MNCV between groups 2 and 3 (p > 0.05), MNCV in group 4 were significantly lower than in groups 2 and 3 (p < 0.05). NTE activities were significantly lower in PSP and PSP+lasalocid groups than in control and lasalocid group (p < 0.05). Onset of ataxia in group 4 appeared early and was exacerbated compared to groups 2 and 3. In conclusion, PSP and lasalocid could induce a significant decrease in MNCV and produce ataxia. Neuropathic OPs could be exacerbated by polyether ionophore lasalocid.
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PMID:Effects of organophosphate phenyl saligenin phosphate and polyether carboxylic ionophore lasalocid on motor nerve conduction velocity, neuropathy target esterase enzyme activity, and clinical ataxia in chickens. 1977 11

Organophosphorus (OP) used as pesticides and hydraulic fluids can produce acute poisoning known as OP-induced delayed neuropathy (OPIDN), whose effects take long time to recover. Thus a secure therapeutic strategy to prevent the most serious effects of this poisoning would be welcome. In this study, tri-o-cresyl phosphate (TOCP, 500 mg/kg p.o.) was given to hens, followed or not by nimodipine (1mg/kg i.m.) and calcium gluconate (Ca-glu 5mg/kg i.v.). Six hours after TOCP intoxication, neuropathy target esterase (NTE) activity inhibition was observed, peaking after 24h exceeding 80% inhibition. A fall in the plasmatic calcium levels was noted 12h after TOCP was given and, in the sciatic nerve, Ca(2+) fell 56.4% 24h later; at the same time calcium activated neutral protease (CANP) activity increased 308.7%, an effect that lasted 14 days. Any bird that received therapeutic treatment after TOCP intoxication presented significant signs of OPIDN. These results suggest that NTE may be implicated in the regulation of calcium entrance into cells being responsible for the maintenance of normal function of calcium channels, and that increasing CANP activity is responsible to triggering OPIDN. Thus, with one suitably adjusted dose of nimodipine as well as Ca-glu, we believe that this treatment strategy may be used in humans with acute poisoning by neuropathic OP.
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PMID:Organophosphorus-induced delayed neuropathy: a simple and efficient therapeutic strategy. 1991 63


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