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Amend N, Koller M, Schmitt C, Worek F, Wille T. The suitability of a polydimethylsiloxane-based (PDMS) microfluidic two compartment system for the toxicokinetic analysis of organophosphorus compounds. Toxicol Lett 2023; 388:24-29. [PMID: 37827339 DOI: 10.1016/j.toxlet.2023.10.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 10/05/2023] [Accepted: 10/06/2023] [Indexed: 10/14/2023]
Abstract
Organ-on-a-chip platforms are an emerging technology in experimental and regulatory toxicology (species-specific differences, ethical considerations). They address gaps between in vivo and in vitro models. However, there are still certain limitations considering material, setup and applicability. The current study examined the suitability of a commercially available polydimethylsiloxane-based (PDMS) organ-chip for the toxicokinetic characterization of the highly toxic nerve agent VX and the organophosphate pesticide parathion. The respective concentrations of 1000 µmol/L and 100 µmol/L VX and parathion were chosen deliberately high in order to study concentrations even if high compound absorption by PDMS might occur. Neuronal and liver spheroids, totaling 2 × 106 cells were used to study concentration changes of VX and parathion. In addition, VX enantiomers were quantified. The current study suggests a significant absorption of VX, respectively parathion by PDMS. This might require future investigation of alternative materials or coatings to limit absorption for organophosphorus compounds in toxicokinetic studies.
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Affiliation(s)
- Niko Amend
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany.
| | - Marianne Koller
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany
| | - Christian Schmitt
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany
| | - Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany
| | - Timo Wille
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany; Department F, Medical CBRN Defence, Bundeswehr Medical Academy, Ingolstädter Str 240, Munich 80939, Germany
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2
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Nam JH, Kim MS, Song YJ, Kim CH, Kim WS, Yu CH, Joe HE, Hur GH, Seo MR, Kim Y, Park KE, Choi JY, Chung SJ, Shin YK. Pretreatment of rhesus monkeys with transdermal patches containing physostigmine and procyclidine: implications of the delivery system for the potential application against VX nerve agent intoxication in humans. Arch Toxicol 2023; 97:697-710. [PMID: 36633609 DOI: 10.1007/s00204-022-03438-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 12/21/2022] [Indexed: 01/13/2023]
Abstract
Physostigmine (Phs) is a reversible inhibitor of acetylcholinesterase (AChE) that penetrates the blood-brain barrier (BBB) and could be used to protect the central nervous system (CNS) against the effects of nerve agents. For prophylactic effectiveness, long, steady, and adequate inhibition of AChE activity by Phs is needed to broadly protect against the CNS effects of nerve agents. Here, we evaluated the efficacy of transdermal patches containing Phs and procyclidine (PC) as prophylactic agents. Patches (25 cm2) containing 4.4 mg Phs and 17.8 mg PC had a protective ratio of approximately 78.6-fold in rhesus monkeys challenged with VX nerve agent and given an antidote. Physiologically based pharmacokinetic model in conjunction with an indirect pharmacodynamic (PBPK/PD) was developed for Phs and scaled to rhesus monkeys. The model was able to reproduce the concentration profile and inhibitory effect on AChE of Phs in monkeys, as evidenced by correlation coefficients of 0.994 and 0.992 for 25 cm2 and 49 cm2 patches, respectively (i.e., kinetic data), and 0.989 and 0.968 for 25 cm2 and 49 cm2 patches, respectively (i.e., dynamic data). By extending the monkey PBPK/ PD model to humans, the effective human dose was predicted to be five applications of a 25 cm2 patch (i.e., 22 mg Phs), and two applications of a 49 cm2 patch (i.e., 17.4 mg Phs). Therefore, given that patch application of Phs in rhesus monkeys has a prolonged effect (namely, AChE inhibition of 19.6% for the 25 cm2 patch and 23.0% for the 49 cm2 patch) for up to 216 h, patch formulation of Phs may provide similar protection against nerve agent intoxication in humans.
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Affiliation(s)
- Ji-Hye Nam
- Laboratory of Molecular Pathology and Cancer Genomics, Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826, Republic of Korea
- Logone Bio-Convergence Research Foundation, Seoul, 08394, Republic of Korea
| | - Min-Soo Kim
- College of Pharmacy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Young-Jo Song
- Agency for Defense Development, Yuseong, Daejeon, 34186, Republic of Korea
| | - Chang-Hwan Kim
- Agency for Defense Development, Yuseong, Daejeon, 34186, Republic of Korea
| | - Wang Soo Kim
- Agency for Defense Development, Yuseong, Daejeon, 34186, Republic of Korea
| | - Chi Ho Yu
- Agency for Defense Development, Yuseong, Daejeon, 34186, Republic of Korea
| | - Hae Eun Joe
- Laboratory of Molecular Pathology and Cancer Genomics, College of Pharmacy and Research Institute of Pharmaceutical Science, Seoul National University, Seoul, 08826, Republic of Korea
- Agency for Defense Development, Yuseong, Daejeon, 34186, Republic of Korea
| | - Gyeung Haeng Hur
- Agency for Defense Development, Yuseong, Daejeon, 34186, Republic of Korea
| | - Myeung-Ryun Seo
- Laboratory of Molecular Pathology and Cancer Genomics, Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826, Republic of Korea
| | - Yeongmun Kim
- Laboratory of Molecular Pathology and Cancer Genomics, Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826, Republic of Korea
- Abion Inc, Seoul, 08394, Republic of Korea
| | | | | | - Suk-Jae Chung
- College of Pharmacy, Seoul National University, Seoul, 08826, Republic of Korea.
- Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, 08826, Republic of Korea.
| | - Young Kee Shin
- Laboratory of Molecular Pathology and Cancer Genomics, Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826, Republic of Korea.
- Laboratory of Molecular Pathology and Cancer Genomics, College of Pharmacy and Research Institute of Pharmaceutical Science, Seoul National University, Seoul, 08826, Republic of Korea.
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Thiermann H, Worek F. Oximes should be used routinely in organophosphate poisoning. Br J Clin Pharmacol 2022; 88:5064-5069. [PMID: 35023196 DOI: 10.1111/bcp.15215] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 10/25/2021] [Accepted: 11/02/2021] [Indexed: 11/30/2022] Open
Abstract
In poisoning with organophosphorus compounds, patients can only profit from the regeneration of acetylcholinesterase, when the poison load has dropped below a toxic level. Every measure that allows an increase of synaptic AChE activity at the earliest is essential for timely termination of the cholinergic crisis. Only a drug induced reactivation allows to achieve fast restoration of the inhibited AChE. Obidoxime and pralidoxime have proved to be able to reactivate inhibited cholinesterase thereby saving life of poisoned animals. A plasma level of obidoxime or pralidoxime allowing reactivation in humans poisoned by OP can be adjusted. There is no doubt that obidoxime and pralidoxime are able to reactivate OP inhibited AChE activity in poisoned patients thereby increasing AChE activity and contributing substantially to terminate cholinergic crisis. Hence, a benefit may be expected when substantial reactivation is achieved. A test system allowing determination of red blood cell AChE activity, reactivatability, inhibitory equivalents and BChE activity is available for relatively low cost. If any reactivation is possible while inhibiting equivalents are present, oxime therapy should be maintained. In particular, when balancing the benefit risk assessment, obidoxime or palidoxime should be given as soon as possible and as long as a substantial reactivation may be expected.
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Affiliation(s)
- Horst Thiermann
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany
| | - Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany
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4
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Amend N, Niessen KV, Seeger T, Wille T, Worek F, Thiermann H. Diagnostics and treatment of nerve agent poisoning—current status and future developments. Ann N Y Acad Sci 2020; 1479:13-28. [DOI: 10.1111/nyas.14336] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 02/25/2020] [Accepted: 03/05/2020] [Indexed: 12/20/2022]
Affiliation(s)
- Niko Amend
- Bundeswehr Institute of Pharmacology and Toxicology Munich Germany
| | - Karin V. Niessen
- Bundeswehr Institute of Pharmacology and Toxicology Munich Germany
| | - Thomas Seeger
- Bundeswehr Institute of Pharmacology and Toxicology Munich Germany
| | - Timo Wille
- Bundeswehr Institute of Pharmacology and Toxicology Munich Germany
| | - Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology Munich Germany
| | - Horst Thiermann
- Bundeswehr Institute of Pharmacology and Toxicology Munich Germany
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Cortes N, Sierra K, Alzate F, Osorio EH, Osorio E. Alkaloids of Amaryllidaceae as Inhibitors of Cholinesterases (AChEs and BChEs): An Integrated Bioguided Study. PHYTOCHEMICAL ANALYSIS : PCA 2018; 29:217-227. [PMID: 29044771 DOI: 10.1002/pca.2736] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 09/18/2017] [Accepted: 09/19/2017] [Indexed: 05/27/2023]
Abstract
INTRODUCTION Enzymatic inhibition of acetylcholinesterase (AChE) is an essential therapeutic target for the treatment of Alzheimer's disease (AD) and AChE inhibitors are the first-line drugs for it treatment. However, butyrylcholinesterase (BChE), contributes critically to cholinergic dysfunction associated with AD. Thus, the development of novel therapeutics may involve the inhibition of both cholinesterase enzymes. OBJECTIVE To evaluate, in an integrated bioguided study, cholinesterases alkaloidal inhibitors of Amaryllidaceae species. METHODOLOGY The proposed method combines high-performance thin-layer chromatography (HPTLC) with data analysis by densitometry, enzymatic bioautography with different AChEs and BChEs, the detection of bioactive molecules through gas chromatography mass spectrometry (GC-MS) analysis of spots of interest, and theoretical in silico studies. RESULTS To evaluate the bioguided method, the AChE and BChE inhibitory activities of seven Amaryllidaceae plant extracts were evaluated. The alkaloid extracts of Eucharis bonplandii exhibited a high level of inhibitory activity (IC50 = 0.72 ± 0.05 μg/mL) against human recombinant AChE (hAChE). Regarding human serum BChE (hBChE), the bulb and leaf extracts of Crinum jagus had the highest activity (IC50 = 8.51 ± 0.56 μg/mL and 11.04 ± 1.21 μg/mL, respectively). In the HPTLC spots with high inhibitory activity, several alkaloids were detected using GC-MS, and some of these alkaloids were identified. Galanthamine, galanthamine N-oxide and powelline should be the most prominent inhibitors of substrate accommodation in the active site of the Torpedo californica AChE (TcAChE), hAChE and hBChE enzymes. CONCLUSIONS These results are evidence of the chemical relevance of the Colombian's Amaryllidaceae species for the inhibition of cholinesterases and as potent sources for the palliative treatment of AD. Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- Natalie Cortes
- Grupo de Investigación en Sustancias Bioactivas, Facultad de Ciencias Farmacéuticas y Alimentarias, Universidad de Antioquia UdeA, Calle 70 No, 52-21, Medellín, Colombia
| | - Karina Sierra
- Grupo de Investigación en Sustancias Bioactivas, Facultad de Ciencias Farmacéuticas y Alimentarias, Universidad de Antioquia UdeA, Calle 70 No, 52-21, Medellín, Colombia
| | - Fernando Alzate
- Grupo de Estudios Botánicos, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No, 52-21, Medellín, Colombia
| | - Edison H Osorio
- Departamento de Ciencias Básicas, Universidad Católica Luis Amigó, SISCO, Transversal 51A No. 67B, -90, Medellín, Colombia
| | - Edison Osorio
- Grupo de Investigación en Sustancias Bioactivas, Facultad de Ciencias Farmacéuticas y Alimentarias, Universidad de Antioquia UdeA, Calle 70 No, 52-21, Medellín, Colombia
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Whitmore C, Cook AR, Mann T, Price ME, Emery E, Roughley N, Flint D, Stubbs S, Armstrong SJ, Rice H, Tattersall JEH. The efficacy of HI-6 DMS in a sustained infusion against percutaneous VX poisoning in the guinea-pig. Toxicol Lett 2017; 293:207-215. [PMID: 29129798 DOI: 10.1016/j.toxlet.2017.11.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 11/02/2017] [Accepted: 11/06/2017] [Indexed: 11/29/2022]
Abstract
Post-exposure nerve agent treatment usually includes administration of an oxime, which acts to restore function of the enzyme acetylcholinesterase (AChE). For immediate treatment of military personnel, this is usually administered with an autoinjector device, or devices containing the oxime such as pralidoxime, atropine and diazepam. In addition to the autoinjector, it is likely that personnel exposed to nerve agents, particularly by the percutaneous route, will require further treatment at medical facilities. As such, there is a need to understand the relationship between dose rate, plasma concentration, reactivation of AChE activity and efficacy, to provide supporting evidence for oxime infusions in nerve agent poisoning. Here, it has been demonstrated that intravenous infusion of HI-6, in combination with atropine, is efficacious against a percutaneous VX challenge in the conscious male Dunkin-Hartley guinea-pig. Inclusion of HI-6, in addition to atropine in the treatment, improved survival when compared to atropine alone. Additionally, erythrocyte AChE activity following poisoning was found to be dose dependent, with an increased dose rate of HI-6 (0.48mg/kg/min) resulting in increased AChE activity. As far as we are aware, this is the first study to correlate the pharmacokinetic profile of HI-6 with both its pharmacodynamic action of reactivating nerve agent inhibited AChE and with its efficacy against a persistent nerve agent exposure challenge in the same conscious animal.
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Affiliation(s)
- C Whitmore
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom.
| | - A R Cook
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom
| | - T Mann
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom
| | - M E Price
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom
| | - E Emery
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom
| | - N Roughley
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom
| | - D Flint
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom
| | - S Stubbs
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom
| | - S J Armstrong
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom
| | - H Rice
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom
| | - J E H Tattersall
- CBR (Chemical, Biological, Radiological), Dstl Porton Down, Salisbury, Wiltshire, SP4 0JQ, United Kingdom
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7
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Worek F, Thiermann H, Wille T. The oximes HI-6 and MMB-4 fail to reactivate soman-inhibited human and guinea pig AChE: A kinetic in vitro study. Toxicol Lett 2017; 293:216-221. [PMID: 28993240 DOI: 10.1016/j.toxlet.2017.10.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Revised: 09/26/2017] [Accepted: 10/04/2017] [Indexed: 11/18/2022]
Abstract
Acetylcholinesterase (AChE) inhibited by the organophosphorus nerve (OP) agent soman underlies a spontaneous and extremely rapid dealkylation ("aging") reaction which prevents reactivation by oximes. However, in vivo studies in various, soman poisoned animal species showed a therapeutic effect of oximes, with the exact mechanism of this effect remaining still unclear. In order to get more insight and a basis for the extrapolation of animal data to humans, we applied a dynamic in vitro model with continuous online determination of AChE activity. This model allows to simulate the in vivo toxico- and pharmacokinetics between human and guinea pig AChE with soman and the oximes HI-6 and MMB-4 in order to unravel the species dependent kinetic interactions. It turned out that only HI-6 was able to slow down the ongoing inhibition of human AChE by soman without preventing final complete inhibition of the enzyme. Continuous perfusion of AChE with soman and simultaneous or delayed (8, 15 or 40min) oxime perfusion did not result in a relevant reactivation of AChE (less than 2%). In conclusion, the results of the present study indicate a negligible reactivation of soman-inhibited AChE by oximes at conditions simulating the in vivo poisoning by soman. The observed therapeutic effect of oximes in soman poisoned animals in vivo must be attributed to alternative mechanisms which may not be relevant in humans.
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Affiliation(s)
- Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany.
| | - Horst Thiermann
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany
| | - Timo Wille
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany
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8
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Rice H, Mann TM, Armstrong SJ, Price ME, Green AC, Tattersall JE. The potential role of bioscavenger in the medical management of nerve-agent poisoned casualties. Chem Biol Interact 2016; 259:175-181. [DOI: 10.1016/j.cbi.2016.04.038] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 04/18/2016] [Accepted: 04/28/2016] [Indexed: 11/25/2022]
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9
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Greget R, Dadak S, Barbier L, Lauga F, Linossier-Pierre S, Pernot F, Legendre A, Ambert N, Bouteiller JM, Dorandeu F, Bischoff S, Baudry M, Fagni L, Moussaoui S. Modeling and simulation of organophosphate-induced neurotoxicity: Prediction and validation by experimental studies. Neurotoxicology 2016; 54:140-152. [PMID: 27108687 DOI: 10.1016/j.neuro.2016.04.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 02/07/2016] [Accepted: 04/19/2016] [Indexed: 02/07/2023]
Abstract
Exposure to organophosphorus (OP) compounds, either pesticides or chemical warfare agents, represents a major health problem. As potent irreversible inhibitors of cholinesterase, OP may induce seizures, as in status epilepticus, and occasionally brain lesions. Although these compounds are extremely toxic agents, the search for novel antidotes remains extremely limited. In silico modeling constitutes a useful tool to identify pharmacological targets and to develop efficient therapeutic strategies. In the present work, we developed a new in silico simulator in order to predict the neurotoxicity of irreversible inhibitors of acetyl- and/or butyrylcholinesterase (ChE) as well as the potential neuroprotection provided by antagonists of cholinergic muscarinic and glutamate N-methyl-d-aspartate (NMDA) receptors. The simulator reproduced firing of CA1 hippocampal neurons triggered by exposure to paraoxon (POX), as found in patch-clamp recordings in in vitro mouse hippocampal slices. In the case of POX intoxication, it predicted a preventing action of the muscarinic receptor antagonist atropine sulfate, as well as a synergistic action with the non-competitive NMDA receptor antagonist memantine. These in silico predictions relative to beneficial effects of atropine sulfate combined with memantine were recapitulated experimentally in an in vivo model of POX in adult male Swiss mice using electroencephalic (EEG) recordings. Thus, our simulator is a new powerful tool to identify protective therapeutic strategies against OP central effects, by screening various combinations of muscarinic and NMDA receptor antagonists.
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Affiliation(s)
| | - Selma Dadak
- Institut de Génomique Fonctionnelle, CNRS, UMR-5203, INSERM, U1191, Université de Montpellier, Montpellier F-34094, France
| | - Laure Barbier
- Institut de Recherche Biomédicale des Armées (IRBA), Département de Toxicologie et Risques Chimiques, Brétigny sur Orge, France
| | - Fabien Lauga
- Institut de Recherche Biomédicale des Armées (IRBA), Département de Toxicologie et Risques Chimiques, Brétigny sur Orge, France
| | - Sandra Linossier-Pierre
- Institut de Recherche Biomédicale des Armées (IRBA), Département de Toxicologie et Risques Chimiques, Brétigny sur Orge, France
| | | | | | | | | | - Frédéric Dorandeu
- Institut de Recherche Biomédicale des Armées (IRBA), Département de Toxicologie et Risques Chimiques, Brétigny sur Orge, France; Ecole du Val-de-Grâce, Paris, France
| | | | | | - Laurent Fagni
- Institut de Génomique Fonctionnelle, CNRS, UMR-5203, INSERM, U1191, Université de Montpellier, Montpellier F-34094, France
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Moon J, Chun B, Lee S. Variable response of cholinesterase activities following human exposure to different types of organophosphates. Hum Exp Toxicol 2015; 34:698-706. [DOI: 10.1177/0960327114558890] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We investigated the red blood cell (RBC) acetylcholinesterase (AChE) activities and butyrylcholinesterase (BChE) activities at presentation to the emergency department (ED) and at 24 h after presentation following poisoning by dichlorvos, fenitrothion, or ethyl p-nitrophenol thio-benzene phosphonate (EPN). Although the patients from different groups had similar characteristics at presentation such as time interval from ingestion to presentation to the ED and the amount of organophosphate ingested, the dichlorvos group had significantly lower BChE levels than the fenitrothion group and lower RBC cholinesterase activity than the EPN group. Patients poisoned with EPN or dichlorvos had significantly higher inhibition of BChE activities from baseline than RBC AChE activities at presentation. Twenty four hours after administration of pralidoxime, RBC AChE activities had increased in patients in the dichlorvos and EPN groups, while RBC AChE activities had slightly decreased in the fenitrothion group. BChE activities increased significantly in the dichlorvos group but decreased in the EPN group. The recovery patterns of RBC AChE and BChE activities did not match in any particular individual. This study showed that the patterns of inhibition and recovery of the activities of two cholinesterases after treatment are highly variable according to the organophosphate and in different individuals.
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Affiliation(s)
- J Moon
- Department of Emergency Medicine, Chonnam National University Medical School, Gwangju, South Korea
| | - B Chun
- Department of Emergency Medicine, Chonnam National University Medical School, Gwangju, South Korea
| | - S Lee
- Department of Emergency Medicine, Chonnam National University Medical School, Gwangju, South Korea
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11
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Worek F, Horn G, Wille T, Thiermann H. Adaptation of a dynamic in vitro model with real-time determination of butyrylcholinesterase activity in the presence of cyclosarin and an oxime. Toxicol In Vitro 2015; 29:162-7. [DOI: 10.1016/j.tiv.2014.10.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2014] [Revised: 09/29/2014] [Accepted: 10/06/2014] [Indexed: 02/03/2023]
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Herkert NM, Freude G, Kunz U, Thiermann H, Worek F. Comparative kinetics of organophosphates and oximes with erythrocyte, muscle and brain acetylcholinesterase. Toxicol Lett 2012; 209:173-8. [PMID: 22230262 DOI: 10.1016/j.toxlet.2011.12.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2011] [Revised: 12/20/2011] [Accepted: 12/23/2011] [Indexed: 11/27/2022]
Abstract
There is an ongoing debate whether oximes can effectively counteract the effects of organophosphorus compounds (OP) on brain acetylcholinesterase (AChE) activity and whether there are differences in the kinetic properties of brain and erythrocyte AChE. In order to investigate the kinetics of AChE from different tissues and species the well established dynamically working in vitro model with real-time determination of membrane-bound AChE activity was adapted for use with brain AChE. The enzyme reactor, that was loaded with brain, erythrocyte or muscle AChE, was continuously perfused with substrate and chromogen while AChE activity was on-line analyzed in a flow-through detector. It was possible to determine the Michaelis-Menten constants of human erythrocyte, muscle and brain AChE which were almost identical. In addition, the inhibition kinetics of sarin and paraoxon as well as the reactivation kinetics of obidoxime and HI 6 were determined with human, swine and guinea pig brain and erythrocyte AChE. It was found that the inhibition and reactivation kinetics of brain and erythrocyte AChE were highly comparable in all tested species. These data support the view that AChE from different tissue has similar kinetic properties and that brain AChE is comparably susceptible toward reactivation by oximes.
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Affiliation(s)
- Nadja M Herkert
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany
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13
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Worek F, Eyer P, Thiermann H. Determination of acetylcholinesterase activity by the Ellman assay: a versatile tool for in vitro research on medical countermeasures against organophosphate poisoning. Drug Test Anal 2011; 4:282-91. [PMID: 21998030 DOI: 10.1002/dta.337] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Revised: 07/01/2011] [Accepted: 07/05/2011] [Indexed: 11/08/2022]
Abstract
Inhibition of acetylcholinesterase (AChE) is the main mechanism of action of organophosphorus compounds (OP), and AChE reactivators (oximes) are at present the only causal therapeutic approach. Being the key target of OP toxicity, AChE may serve as a valuable tool for diagnosis of OP exposure as well as for the investigation of the kinetics of interactions between OP and oximes. At present, the rapid, simple, and cheap spectrophotometric Ellman assay is widely used for diagnosis, therapeutic monitoring and in vitro kinetic investigations. Application of the assay for investigation of the interactions between AChE, inhibitors, and oximes requires the consideration of potential matrix effects (e.g. hemoglobin), side reactions (e.g. oximolysis of substrate) and other determinants (e.g. pH, temperature). By taking these factors into account, the Ellman assay allows the precise and reproducible determination of kinetic constants as a basis for the understanding of toxic OP effects and for the development of improved therapies against poisoning by OP. In addition, advanced applications of the Ellman assay, for example, in a dynamic in vitro model for the real-time activity determination of membrane-bound AChE, enables the proper investigation of relevant tissue, primarily respiratory muscle, and extends the applicability of this method.
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Affiliation(s)
- Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, Munich, Germany.
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Seeger T, Niessen K, Langer P, Gerhardus J, Worek F, Friess H, Bumm R, Mihaljevic A, Thiermann H. Restoration of nerve agent inhibited muscle force production in human intercostal muscle strips with HI 6. Toxicol Lett 2011; 206:72-6. [DOI: 10.1016/j.toxlet.2011.07.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Revised: 06/21/2011] [Accepted: 07/15/2011] [Indexed: 01/17/2023]
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Herkert N, Schulz S, Wille T, Thiermann H, Hatz R, Worek F. Pre- and post-treatment effect of physostigmine on soman-inhibited human erythrocyte and muscle acetylcholinesterase in vitro. Toxicol Appl Pharmacol 2011; 253:7-13. [DOI: 10.1016/j.taap.2011.03.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Revised: 03/04/2011] [Accepted: 03/06/2011] [Indexed: 11/16/2022]
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Herkert NM, Thiermann H, Worek F. In vitro kinetic interactions of pyridostigmine, physostigmine and soman with erythrocyte and muscle acetylcholinesterase from different species. Toxicol Lett 2011; 206:41-6. [PMID: 21414391 DOI: 10.1016/j.toxlet.2011.03.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Accepted: 03/02/2011] [Indexed: 10/18/2022]
Abstract
The low effectiveness of atropine and oxime treatment in soman poisoning may be enhanced by carbamates pre-treatment. For ethical reasons medical countermeasures can only be tested in animal models despite the fact of substantial species differences. With this kinetic in vitro study the interactions between pyridostigmine, physostigmine and soman with human, Rhesus monkey, swine and guinea pig erythrocyte AChE were investigated. In addition, the effect of the carbamates on the residual activity and enzyme recovery after soman inhibition was examined with erythrocyte and intercostal muscle AChE from these species with a dynamic in vitro model with real-time determination of AChE activity. Only small to moderate species differences of the inhibition and decarbamylation kinetics were recorded. It was possible to show that with erythrocyte and muscle AChE a similar level of protection by carbamates and reactivation after discontinuation of the carbamates and soman could be observed. Thus, these data indicate that carbamate pre-treatment is expected to protect a critical level of muscle AChE and confirm the presumption that erythrocyte AChE may serve as a surrogate for synaptic AChE. Hence, these and previous data fortify the notion that erythrocyte AChE is a proper tool for in vitro kinetic studies as well as for therapeutic monitoring in experimental and clinical studies.
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Affiliation(s)
- N M Herkert
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany
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