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Amend N, Timperley CM, Bird M, Green AC, Worek F, Seeger T. The use of bispyridinium non-oxime analogues for the restoration of nerve agent impaired neuromuscular transmission in rat hemidiaphragms - Structure optimization. Toxicol Lett 2024; 397:42-47. [PMID: 38723915 DOI: 10.1016/j.toxlet.2024.04.015] [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: 03/20/2024] [Revised: 04/21/2024] [Accepted: 04/29/2024] [Indexed: 06/16/2024]
Abstract
Organophosphate pesticide poisoning challenges health care systems worldwide. Furthermore, nerve agents remain a continuous threat. The treatment options for organophosphate poisoning have virtually been unchanged for decades, relying on symptomatic treatment and the use of oximes to indirectly restore neuromuscular function. Hence, compounds targeting directly nicotinic acetylcholine receptors (nAChRs) might substantially improve treatment options. The current study investigated a series of bispyridinium analogues with a trimethylene or 2,2'-diethyloxy linker in a rat hemidiaphragm model, using indirect field stimulation. Methyl- and ethyl-substituted bispyridinium analogues restored neuromuscular function up to 37 ± 17% (MB419, a 3-methyl analogue) at a stimulation frequency of 20 Hz. The bispyridinium analogues with a 2- or 3-methyl group, or a 2- or 3-ethyl group, tended towards a higher restoration of neuromuscular function than those with a 4-methyl or 4-ethyl group, respectively. The current data can be used for future studies to optimize structure-based molecular modeling of compounds targeting the nAChR.
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Affiliation(s)
- Niko Amend
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, Munich 80937, Germany; Walther-Straub-Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Goethestr. 33, Munich 80336, Germany.
| | - Christopher M Timperley
- Chemical, Biological and Radiological (CBR) Division, Defence Science and Technology Laboratory (Dstl), Porton Down, Salisbury, Wiltshire SP4 0JQ, UK
| | - Mike Bird
- Chemical, Biological and Radiological (CBR) Division, Defence Science and Technology Laboratory (Dstl), Porton Down, Salisbury, Wiltshire SP4 0JQ, UK
| | - A Christopher Green
- Chemical, Biological and Radiological (CBR) Division, Defence Science and Technology Laboratory (Dstl), Porton Down, Salisbury, Wiltshire SP4 0JQ, UK
| | - Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, Munich 80937, Germany
| | - Thomas Seeger
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, Munich 80937, Germany
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Buckley NA, Jayawardane P, Weerasinghe V, Dawson AH, Dassanayake TL. Serial repetitive nerve stimulation studies in organophosphorus poisoning indicate two distinct pathophysiological processes occur at the neuromuscular junction in the intermediate syndrome. Clin Toxicol (Phila) 2024; 62:219-228. [PMID: 38738692 PMCID: PMC11147452 DOI: 10.1080/15563650.2024.2343744] [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: 11/15/2023] [Accepted: 04/11/2024] [Indexed: 05/14/2024]
Abstract
INTRODUCTION Intermediate syndrome is an important cause of respiratory failure following acute organophosphorus pesticide poisoning. The objective of this study was to examine the pathophysiology of this syndrome by analysis of sequential repetitive nerve stimulation studies in patients with acute organophosphorus pesticide poisoning. METHODS Thirty-four consenting symptomatic patients with acute organophosphorus pesticide poisoning with intermediate syndrome (n = 10) or a milder forme fruste intermediate syndrome (n = 24) were assessed prospectively with daily physical examination and repetitive nerve stimulation done on the right and left median and ulnar nerves. The compound muscle action potential at 1, 3, 10, 15, 20 and 30 Hertz was measured with a train of ten stimuli. The amplitudes of the resulting stimuli were normalized to the first stimulus (100 per cent) and plotted against time. The decrease in the area under the curve of all the second stimulus compound muscle action potentials in the first 0.3 seconds was measured as a means of quantifying the refractory block. The decrease in the area under the curve under the 10, 15, 20 and 30 Hertz compound muscle action potentials relative to this pooled second stimulus compound muscle action potentials-area under the curve indicated the extent of additional rate-dependent block (decreasing compound muscle action potential-area under the curve over the first 0.3 seconds after the first stimulus with increasing Hertz). RESULTS These new measurements strongly correlated with the severity of weakness. Refractory block was seen in most patients but was more severe in those with intermediate syndrome than those with forme fruste (partial) intermediate syndrome (median 55 per cent versus 16 per cent, P = 0.0001). Similar large differences were found for rate-dependent block (30 per cent versus 7 per cent, P = 0.001), which was uncommon in forme fruste intermediate syndrome but found in nine out of 10 patients with intermediate syndrome. Rate dependent block was generally only observed after 24 hours. The simplest strong predictor was total block at 30 Hertz repetitive nerve stimulation (89 per cent [interquartile range 73 to 94 per cent] versus 21 per cent [4 to 55 per cent]; P < 0.0001), which was very similar to total block calculated by summing other calculations. DISCUSSION These findings likely represent depolarization and desensitization block from prolonged excessive cholinergic stimulation but it is not clear if these are from pre- or post-synaptic pathology. An animal model of intermediate syndrome with repetitive nerve stimulation studies might enable a better pathophysiological understanding of the two types of block. LIMITATIONS The limited number of repetitive nerve stimulation studies performed were sufficient to demonstrate proof-of-concept, but further studies with more patients are needed to better define the correlates, clinical relevance and possible diagnostic/prognostic roles for the use of this technique. CONCLUSION There are two easily distinguishable pathophysiological abnormalities in the neuromuscular block in intermediate syndrome. While they often coincide, both may be observed in isolation. The total and rate-dependent block at 30 Hertz are strongly associated with more severe weakness.
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Affiliation(s)
- Nicholas A. Buckley
- South Asian Clinical Toxicology Research Collaboration (SACTRC), Faculty of Medicine, University of Peradeniya, Peradeniya, Sri Lanka
- Translational Australian Clinical Toxicology (TACT) Research Group, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Pradeepa Jayawardane
- South Asian Clinical Toxicology Research Collaboration (SACTRC), Faculty of Medicine, University of Peradeniya, Peradeniya, Sri Lanka
- Department of Pharmacology, Faculty of Medical Sciences, University of Sri Jayewardenepura, Nugegoda, Sri Lanka
| | - Vajira Weerasinghe
- South Asian Clinical Toxicology Research Collaboration (SACTRC), Faculty of Medicine, University of Peradeniya, Peradeniya, Sri Lanka
- Translational Australian Clinical Toxicology (TACT) Research Group, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Andrew H. Dawson
- South Asian Clinical Toxicology Research Collaboration (SACTRC), Faculty of Medicine, University of Peradeniya, Peradeniya, Sri Lanka
- Translational Australian Clinical Toxicology (TACT) Research Group, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Tharaka Lagath Dassanayake
- South Asian Clinical Toxicology Research Collaboration (SACTRC), Faculty of Medicine, University of Peradeniya, Peradeniya, Sri Lanka
- Department of Physiology, Faculty of Medicine, University of Peradeniya, Peradeniya, Sri Lanka
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Amend N, Timperley CM, Bird M, Green AC, Worek F, Seeger T. Restoration of nerve agent impaired neuromuscular transmission in rat diaphragm by bispyridinium non-oximes - Structure-activity relationships. Toxicology 2024; 503:153741. [PMID: 38311098 DOI: 10.1016/j.tox.2024.153741] [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: 01/09/2024] [Revised: 01/29/2024] [Accepted: 02/01/2024] [Indexed: 02/06/2024]
Abstract
Organophosphate (OP) poisoning is currently treated with atropine, oximes and benzodiazepines. The nicotinic signs, i.e., respiratory impairment, can only be targeted indirectly via the use of oximes as reactivators of OP-inhibited acetylcholinesterase. Hence, compounds selectively targeting nicotinic acetylcholine receptors (nAChRs) might fundamentally improve current treatment options. The bispyridinium compound MB327 has previously shown some therapeutic effect against nerve agents in vitro and in vivo. Nevertheless, compound optimization was deemed necessary, due to limitations (e.g., toxicity and efficacy). The current study investigated a series of 4-tert-butyl bispyridinium compounds and of corresponding bispyridinium compounds without substituents in a rat diaphragm model using an indirect field stimulation technique. The length of the respective linker influenced the ability of the bispyridinium compounds to restore muscle function in rat hemidiaphragms. The current data show structure-activity relationships for a series of bispyridinium compounds and provide insight for future structure-based molecular modeling.
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Affiliation(s)
- Niko Amend
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany; Walther-Straub-Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Goethestr. 33, 80336 Munich, Germany.
| | - Christopher M Timperley
- Chemical, Biological and Radiological (CBR) Division, Defence Science and Technology Laboratory (Dstl), Porton Down, Salisbury, Wiltshire SP4 0JQ, UK
| | - Mike Bird
- Chemical, Biological and Radiological (CBR) Division, Defence Science and Technology Laboratory (Dstl), Porton Down, Salisbury, Wiltshire SP4 0JQ, UK
| | - A Christopher Green
- Chemical, Biological and Radiological (CBR) Division, Defence Science and Technology Laboratory (Dstl), Porton Down, Salisbury, Wiltshire SP4 0JQ, UK
| | - Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany
| | - Thomas Seeger
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany
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Prchalova E, Kohoutova Z, Knittelova K, Malinak D, Musilek K. Strategies for enhanced bioavailability of oxime reactivators in the central nervous system. Arch Toxicol 2023; 97:2839-2860. [PMID: 37642747 DOI: 10.1007/s00204-023-03587-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 08/10/2023] [Indexed: 08/31/2023]
Abstract
Oxime reactivators of acetylcholinesterase are commonly used to treat highly toxic organophosphate poisoning. They are effective nucleophiles that can restore the catalytic activity of acetylcholinesterase; however, their main limitation is the difficulty in crossing the blood-brain barrier (BBB) because of their strongly hydrophilic nature. Various approaches to overcome this limitation and enhance the bioavailability of oxime reactivators in the CNS have been evaluated; these include structural modifications, conjugation with molecules that have transporters in the BBB, bypassing the BBB through intranasal delivery, and inhibition of BBB efflux transporters. A promising approach is the use of nanoparticles (NPs) as the delivery systems. Studies using mesoporous silica nanomaterials, poly (L-lysine)-graft-poly(ethylene oxide) NPs, metallic organic frameworks, poly(lactic-co-glycolic acid) NPs, human serum albumin NPs, liposomes, solid lipid NPs, and cucurbiturils, have shown promising results. Some NPs are considered as nanoreactors for organophosphate detoxification; these combine bioscavengers with encapsulated oximes. This study provides an overview and critical discussion of the strategies used to enhance the bioavailability of oxime reactivators in the central nervous system.
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Affiliation(s)
- Eliska Prchalova
- Faculty of Science, Department of Chemistry, University of Hradec Kralove, Rokitanskeho 62, 500 03, Hradec Kralove, Czech Republic
| | - Zuzana Kohoutova
- Faculty of Science, Department of Chemistry, University of Hradec Kralove, Rokitanskeho 62, 500 03, Hradec Kralove, Czech Republic
| | - Karolina Knittelova
- Faculty of Science, Department of Chemistry, University of Hradec Kralove, Rokitanskeho 62, 500 03, Hradec Kralove, Czech Republic
| | - David Malinak
- Faculty of Science, Department of Chemistry, University of Hradec Kralove, Rokitanskeho 62, 500 03, Hradec Kralove, Czech Republic.
- Biomedical Research Centre, University Hospital in Hradec Kralove, Sokolska 581, 500 05, Hradec Kralove, Czech Republic.
| | - Kamil Musilek
- Faculty of Science, Department of Chemistry, University of Hradec Kralove, Rokitanskeho 62, 500 03, Hradec Kralove, Czech Republic.
- Biomedical Research Centre, University Hospital in Hradec Kralove, Sokolska 581, 500 05, Hradec Kralove, Czech Republic.
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Ramadori GP. Organophosphorus Poisoning: Acute Respiratory Distress Syndrome (ARDS) and Cardiac Failure as Cause of Death in Hospitalized Patients. Int J Mol Sci 2023; 24:ijms24076658. [PMID: 37047631 PMCID: PMC10094912 DOI: 10.3390/ijms24076658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 03/22/2023] [Accepted: 03/31/2023] [Indexed: 04/05/2023] Open
Abstract
Industrial production of food for animals and humans needs increasing amounts of pesticides, especially of organophosphates, which are now easily available worldwide. More than 3 million cases of acute severe poisoning are estimated to occur worldwide every year, and even more cases remain unreported, while 200,000–350,000 incidentally or intentionally poisoned people die every year. Diagnostic and therapeutic procedures in organophosphate poisoning have, however, remained unchanged. In addition to several neurologic symptoms (miosis, fasciculations), hypersecretion of salivary, bronchial, and sweat glands, vomiting, diarrhea, and loss of urine rapidly induce dehydration, hypovolemia, loss of conscience and respiratory distress. Within hours, signs of acidosis due to systemic hypoxia can be observed at first laboratory investigation after hospitalization. While determination of serum-cholinesterase does not have any diagnostic value, it has been established that hypoalbuminemia alone or accompanied by an increase in creatinine, lactate, or C-reactive protein serum levels has negative prognostic value. Increased serum levels of C-reactive protein are a sign of systemic ischemia. Protective mechanical ventilation should be avoided, if possible. In fact, acute respiratory distress syndrome characterized by congestion and increased weight of the lung, accompanied by heart failure, may become the cause of death. As the excess of acetylcholine at the neuronal level can persist for weeks until enough newly, locally synthesized acetylcholinesterase becomes available (the value of oximes in reducing this time is still under debate), after atropine administration, intravenous albumin and fluid infusion should be the first therapeutic interventions to reestablish normal blood volume and normal tissue oxygenation, avoiding death by cardiac arrest.
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Kuznetsova DA, Gaynanova GA, Vasilieva EA, Pavlov RV, Zueva IV, Babaev VM, Kuznetsov DM, Voloshina AD, Petrov KA, Zakharova LY, Sinyashin OG. Oxime Therapy for Brain AChE Reactivation and Neuroprotection after Organophosphate Poisoning. Pharmaceutics 2022; 14:pharmaceutics14091950. [PMID: 36145698 PMCID: PMC9506492 DOI: 10.3390/pharmaceutics14091950] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 08/31/2022] [Accepted: 09/09/2022] [Indexed: 11/25/2022] Open
Abstract
One of the main problems in the treatment of poisoning with organophosphorus (OPs) inhibitors of acetylcholinesterase (AChE) is low ability of existing reactivators of AChE that are used as antidotes to cross the blood-brain barrier (BBB). In this work, modified cationic liposomes were developed that can penetrate through the BBB and deliver the reactivator of AChE pralidoxime chloride (2-PAM) into the brain. Liposomes were obtained on the basis of phosphatidylcholine and imidazolium surfactants. To obtain the composition optimized in terms of charge, stability, and toxicity, the molar ratio of surfactant/lipid was varied. For the systems, physicochemical parameters, release profiles of the substrates (rhodamine B, 2-PAM), hemolytic activity and ability to cause hemagglutination were evaluated. Screening of liposome penetration through the BBB, analysis of 2-PAM pharmacokinetics, and in vivo AChE reactivation showed that modified liposomes readily pass into the brain and reactivate brain AChE in rats poisoned with paraoxon (POX) by 25%. For the first time, an assessment was made of the ability of imidazolium liposomes loaded with 2-PAM to reduce the death of neurons in the brains of mice. It was shown that intravenous administration of liposomal 2-PAM can significantly reduce POX-induced neuronal death in the hippocampus.
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7
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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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8
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Steindl D, Boehmerle W, Körner R, Praeger D, Haug M, Nee J, Schreiber A, Scheibe F, Demin K, Jacoby P, Tauber R, Hartwig S, Endres M, Eckardt KU. Novichok nerve agent poisoning. Lancet 2021; 397:249-252. [PMID: 33357496 DOI: 10.1016/s0140-6736(20)32644-1] [Citation(s) in RCA: 69] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 11/28/2020] [Accepted: 12/02/2020] [Indexed: 11/21/2022]
Affiliation(s)
- David Steindl
- Department of Nephrology and Medical Intensive Care, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Wolfgang Boehmerle
- Department of Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Roland Körner
- Department of Nephrology and Medical Intensive Care, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Damaris Praeger
- Department of Cardiology and Angiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Marcel Haug
- Department of Cardiology and Angiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Jens Nee
- Department of Nephrology and Medical Intensive Care, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Adrian Schreiber
- Department of Nephrology and Medical Intensive Care, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Franziska Scheibe
- Department of Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Katharina Demin
- Department of Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | | | - Rudolf Tauber
- Institute of Laboratory Medicine, Clinical Chemistry and Pathobiochemistry, Charité-Universitätsmedizin Berlin, Berlin, Germany; Labor Berlin Charité Vivantes GmbH, Berlin, Germany
| | - Sven Hartwig
- Institute of Legal Medicine and Forensic Sciences, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Matthias Endres
- Department of Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Kai-Uwe Eckardt
- Department of Nephrology and Medical Intensive Care, Charité-Universitätsmedizin Berlin, Berlin, Germany.
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9
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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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10
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Pashirova TN, Braïki A, Zueva IV, Petrov KA, Babaev VM, Burilova EA, Samarkina DA, Rizvanov IK, Souto EB, Jean L, Renard PY, Masson P, Zakharova LY, Sinyashin OG. Combination delivery of two oxime-loaded lipid nanoparticles: Time-dependent additive action for prolonged rat brain protection. J Control Release 2018; 290:102-111. [PMID: 30308259 DOI: 10.1016/j.jconrel.2018.10.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 10/06/2018] [Accepted: 10/08/2018] [Indexed: 12/26/2022]
Abstract
A novel approach for brain protection against poisoning by organophosphorus agents is developed based on the combination treatment of dual delivery of two oximes. Pralidoxime chloride (2-PAM) and a novel reactivator, 6-(5-(6,7-dimethoxy-3,4-dihydroisoquinolin-2(1H)-yl)pentyl)-3-hydroxy picolinaldehyde oxime (3-HPA), have been loaded in solid-lipid nanoparticles (SLNs) to offer distinct release profile and systemic half-life for both oximes. To increase the therapeutic time window of both oximes, SLNs with two different compartments were designed to load each respective drug. Oxime-loaded SLNs of hydrodynamic diameter between 100 and 160 nm and negative zeta potential (-30 to -25 mV) were stable for a period of 10 months at 4 °C. SLNs displayed longer circulation time in the bloodstream compared to free 3-HPA and free 2-PAM. Oxime-loaded SLNs were suitable for intravenous (iv) administration. Paraoxon-poisoned rats (0.8 × LD50) were treated with 3-HPA-loaded SLNs and 2-PAM+3-HPA-loaded SLNs at the dose of 3-HPA and 2-PAM of 5 mg/kg. Brain AChE reactivation up to 30% was slowly achieved in 5 h after administration of 3-HPA-SLNs. For combination therapy with two oximes, a time-dependent additivity and increased reactivation up to 35% were observed.
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Affiliation(s)
- Tatiana N Pashirova
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center of RAS, Arbuzov St., 8, Kazan 420088, Russia.
| | - Anissa Braïki
- Normandie Univ, UNIROUEN, INSA Rouen, CNRS, COBRA (UMR 6014), Rouen, France
| | - Irina V Zueva
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center of RAS, Arbuzov St., 8, Kazan 420088, Russia
| | - Konstantin A Petrov
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center of RAS, Arbuzov St., 8, Kazan 420088, Russia; Kazan Federal University, Kremlyovskaya St., 18, Kazan 420008, Russia
| | - Vasily M Babaev
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center of RAS, Arbuzov St., 8, Kazan 420088, Russia
| | - Evgenia A Burilova
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center of RAS, Arbuzov St., 8, Kazan 420088, Russia; Kazan Federal University, Kremlyovskaya St., 18, Kazan 420008, Russia
| | - Darya A Samarkina
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center of RAS, Arbuzov St., 8, Kazan 420088, Russia
| | - Ildar Kh Rizvanov
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center of RAS, Arbuzov St., 8, Kazan 420088, Russia
| | - Eliana B Souto
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal; REQUIMTE/LAQV, Group of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
| | - Ludovic Jean
- Normandie Univ, UNIROUEN, INSA Rouen, CNRS, COBRA (UMR 6014), Rouen, France
| | - Pierre-Yves Renard
- Normandie Univ, UNIROUEN, INSA Rouen, CNRS, COBRA (UMR 6014), Rouen, France
| | - Patrick Masson
- Kazan Federal University, Kremlyovskaya St., 18, Kazan 420008, Russia
| | - Lucia Ya Zakharova
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center of RAS, Arbuzov St., 8, Kazan 420088, Russia.
| | - Oleg G Sinyashin
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center of RAS, Arbuzov St., 8, Kazan 420088, Russia
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11
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Niessen K, Seeger T, Rappenglück S, Wein T, Höfner G, Wanner K, Thiermann H, Worek F. In vitro pharmacological characterization of the bispyridinium non-oxime compound MB327 and its 2- and 3-regioisomers. Toxicol Lett 2018; 293:190-197. [DOI: 10.1016/j.toxlet.2017.10.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 09/29/2017] [Accepted: 10/08/2017] [Indexed: 11/27/2022]
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12
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Lin CC, Hung DZ, Chen HY, Hsu KH. The effectiveness of patient-tailored treatment for acute organophosphate poisoning. Biomed J 2016; 39:391-399. [PMID: 28043418 PMCID: PMC6138500 DOI: 10.1016/j.bj.2016.11.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 04/13/2016] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND To determine a new pralidoxime (PAM) treatment guideline based on the severity of acute organophosphate intoxication patients, APACHE II score, and dynamic changes in serum butyrylcholinesterase (BuChE) activity. METHODS This is a randomization trial. All patients received supportive care measurements and atropinization. Each enrolled patient was treated with 2 gm PAM intravenously as the loading dose. The control group was treated according to the WHO's recommended PAM regimen, and the experimental group was treated according to their APACHE II scores and dynamic changes in BuChE activity. If a patient's APACHE II score was ≧26 or there was no elevation in BuChE activity at the 12th hour when compared to the 6th, doses of 1 g/h PAM (i.e., doubled WHO's recommended PAM regimen) were given. The levels of the serum BuChE and red blood cells acetylcholinesterase and the serum PAM levels were also measured. RESULTS Forty-six organophosphate poisoning patients were enrolled in this study. There were 24 patients in the control group and 22 patients in the experimental group. The hazard ratio of death in the control group to that of the experimental group was 111.51 (95% CI: 1.17-1.613.45; p = 0.04). The RBC acetylcholinesterase level was elevated in the experimental group but was not in the control group. The experimental group did not exhibit a higher PAM blood level than did the control group. CONCLUSION The use of PAM can be guided by patient severity. Thus, may help to improve the outcomes of organophosphate poisoning patients.
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Affiliation(s)
- Chih-Chuan Lin
- Department of Emergency Medicine, Chang Gung Memorial Hospital at Linkou, Chang Gung University College of Medicine, Taoyuan, Taiwan; College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Dong-Zong Hung
- Department of Emergency Medicine, Toxicology Center, China Medical University Hospital, Taichung, Taiwan
| | - Hsien-Yi Chen
- Department of Emergency Medicine, Chang Gung Memorial Hospital at Linkou, Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - Kuang-Hung Hsu
- Laboratory for Epidemiology, Department of Health Care Management, and Healthy Aging Research Center, Chang Gung University, Taoyuan, Taiwan; Department of Urology, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan.
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Plaschke K, Petersen KA, Frankenhauser S, Weigand MA, Kopitz J, Bardenheuer HJ. The Impact of Plasma Cholinergic Enzyme Activity and Other Risk Factors for the Development of Delirium in Patients Receiving Palliative Care. J Pain Symptom Manage 2016; 52:525-532. [PMID: 27401519 DOI: 10.1016/j.jpainsymman.2016.05.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 04/01/2016] [Accepted: 05/20/2016] [Indexed: 11/20/2022]
Abstract
CONTEXT Delirium is an important complication in palliative care patients. One of the potential risk factors for cognitive disorders is deterioration in cholinergic neurotransmission. Anticholinergic medications are known to be important owing to the association of their metabolites with significant morbidity, which is often the result of cumulative effects of medications (anticholinergic burden). Additionally, cholinergic enzymes are possible candidates reflecting the cholinergic situation in patients. However, the role of cholinesterases (CHE) for delirium in palliative care patients is unknown. OBJECTIVES Following local Ethics Board approval and written informed consent, we recruited a cohort of patients who had been admitted to the Heidelberg University Palliative Care Unit related to CHE and other factors at risk for delirium. METHODS Delirium was assessed using the Nursing Delirium Screening Scale once daily in all cancer patients (N = 100) during their stay on the palliative care unit. In a subgroup of 69 probes, blood samples were analyzed for acetyl- and butyrylcholinesterase activity spectrophotometrically. Furthermore, patients' medications were recorded. Logistic regression analysis was used to evaluate potential predictors of delirium. RESULTS Delirium was identified in 29% of patients. Karnofsky Performance Status Scale score was significantly lower (P = 0.021) and mortality higher (P = 0.018) in patients with delirium. Plasma CHE activity was not associated with delirium. However, a significant effect of anticholinergic medication on plasma CHE activity was detected; so far midazolam (P = 0.01) seems to play an important role in that process. CONCLUSION Special care might be necessary with anticholinergic medication to minimize risk for delirium in palliative cancer patients.
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Affiliation(s)
- Konstanze Plaschke
- Department of Anesthesiology, University of Heidelberg, Heidelberg, Germany.
| | | | | | - Markus A Weigand
- Department of Anesthesiology, University of Heidelberg, Heidelberg, Germany
| | - Jürgen Kopitz
- Department of Pathology, University of Heidelberg, Heidelberg, Germany
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Plaschke K, Weigand MA, Fricke F, Kopitz J. Neuroinflammation: effect of surgical stress compared to anaesthesia and effect of physostigmine. Neurol Res 2016; 38:397-405. [DOI: 10.1080/01616412.2016.1173889] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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15
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Weimer I, Worek F, Seeger T, Thiermann H, Eckle VS, Grasshoff C, Antkowiak B. Self-regeneration of neuromuscular function following soman and VX poisoning in spinal cord-skeletal muscle cocultures. Toxicol Lett 2016; 244:149-153. [PMID: 26256036 DOI: 10.1016/j.toxlet.2015.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Revised: 07/31/2015] [Accepted: 08/04/2015] [Indexed: 12/21/2022]
Abstract
Aside from nerve agents, various highly toxic pesticides belong to the group of organophosphorus (OP) compounds, thereby causing a large number of intoxications every year. Unfortunately, there are still shortcomings in the current treatment for OP poisoning and research on novel therapeutic options is restricted in several aspects. In this study we investigated the suitability of organotypic cocultures for pharmacological in vitro studies involving OP compounds. These slice cultures are derived from murine spinal cord and muscle tissue forming functional neuromuscular synapses, which trigger spontaneous contractions of muscle fibers. Using video microscopy to quantify muscle activity, we assessed the viability of cocultures after exposure to soman and VX, and the associated loss and recovery of neuromuscular function. Antidotal treatment was not provided. The application of nerve agents led to an almost complete loss of muscle activity. However, cell cultures regained equivalent muscular function to the control situation three and seven days after intoxication. In summary, the tested in vitro system could be a promising tool for the investigation of long term effects and therapeutic options for OP poisoning.
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Affiliation(s)
- Isabel Weimer
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany; Department of Anaesthesiology, Experimental Anaesthesiology Section, Eberhard-Karls-University, Waldhoernlestrasse 22, 72072 Tuebingen, Germany.
| | - Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany
| | - Thomas Seeger
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany
| | - Horst Thiermann
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany
| | - Veit-Simon Eckle
- Department of Anaesthesiology, Experimental Anaesthesiology Section, Eberhard-Karls-University, Waldhoernlestrasse 22, 72072 Tuebingen, Germany
| | - Christian Grasshoff
- Department of Anaesthesiology, Experimental Anaesthesiology Section, Eberhard-Karls-University, Waldhoernlestrasse 22, 72072 Tuebingen, Germany
| | - Bernd Antkowiak
- Department of Anaesthesiology, Experimental Anaesthesiology Section, Eberhard-Karls-University, Waldhoernlestrasse 22, 72072 Tuebingen, Germany; Werner-Reichardt-Centre for Integrative Neuroscience, Eberhard-Karls-University, 72076 Tuebingen, Germany
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Thiermann H, Worek F, Kehe K. Limitations and challenges in treatment of acute chemical warfare agent poisoning. Chem Biol Interact 2013; 206:435-43. [PMID: 24091052 DOI: 10.1016/j.cbi.2013.09.015] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 09/18/2013] [Accepted: 09/20/2013] [Indexed: 02/02/2023]
Abstract
Recent news from Syria on a possible use of chemical warfare agents made the headlines. Furthermore, the motivation of terrorists to cause maximal harm shifts these agents into the public focus. For incidents with mass casualties appropriate medical countermeasures must be available. At present, the most important threats arise from nerve agents and sulfur mustard. At first, self-protection and protection of medical units from contamination is of utmost importance. Volatile nerve agent exposure, e.g. sarin, results in fast development of cholinergic crisis. Immediate clinical diagnosis can be confirmed on-site by assessment of acetylcholinesterase activity. Treatment with autoinjectors that are filled with 2mg atropine and an oxime (at present obidoxime, pralidoxime, TMB-4 or HI-6) are not effective against all nerve agents. A more aggressive atropinisation has to be considered and more effective oximes (if possible with a broad spectrum or a combination of different oximes) as well as alternative strategies to cope with high acetylcholine levels at synaptic sites should be developed. A further gap exists for the treatment of patients with sustained cholinergic crisis that has to be expected after exposure to persistent nerve agents, e.g. VX. The requirement for long-lasting artificial ventilation can be reduced with an oxime therapy that is optimized by using the cholinesterase status for guidance or by measures (e.g. scavengers) that are able to reduce the poison load substantially in the patients. For sulfur mustard poisoning no specific antidote is available until now. Symptomatic measures as used for treatment of burns are recommended together with surgical or laser debridement. Thus, huge amounts of resources are expected to be consumed as wound healing is impaired. Possible depots of sulfur mustard in tissues may aggravate the situation. More basic knowledge is necessary to improve substantially therapeutic options. The use of stem cells may provide a new and promising option.
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Affiliation(s)
- Horst Thiermann
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany.
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17
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The value of novel oximes for treatment of poisoning by organophosphorus compounds. Pharmacol Ther 2013; 139:249-59. [DOI: 10.1016/j.pharmthera.2013.04.009] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 04/08/2013] [Indexed: 11/23/2022]
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18
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Hrabetz H, Thiermann H, Felgenhauer N, Zilker T, Haller B, Nährig J, Saugel B, Eyer F. Organophosphate poisoning in the developed world - a single centre experience from here to the millennium. Chem Biol Interact 2013; 206:561-8. [PMID: 23685200 DOI: 10.1016/j.cbi.2013.05.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 05/06/2013] [Accepted: 05/08/2013] [Indexed: 12/20/2022]
Abstract
Organophosphate (OP) poisoning is still associated with high morbidity and mortality rates, both in resource-poor settings and in well-developed countries. Despite numerous publications dealing with this particular poison, detailed clinical data on more severe overdoses with these agents are relatively sparsely reported. A retrospective study was consequently conducted on 33 patients with OP poisoning admitted to our intensive care unit (ICU) to provide additional data on clinical features. We included moderate to severe poisonings between 2000 and 2012 who required admission to ICU. Patients ingested dimethyl-OPs in 19 cases, diethyl-OPs in 8 cases and otherwise classified OPs in 6 cases. Death (5/33) occurred rather late and only one of these fatalities died during on-going cholinergic crisis. Of the survivors (28/33), 71% recovered fully while 29% showed predominantly neurological disabilities before being transferred to neurologic rehabilitation. Aspiration pneumonia predominated in 27/33 patients and one patient died in refractory acute respiratory distress syndrome (ARDS). The intermediate syndrome occurred twice and cardiopulmonary resuscitation had to be performed in 6/33 patients. Fatalities showed a higher Poison-severity-score, APACHE-II-score and SOFA-score on admission compared with survivors and they showed significantly longer QTc-time in the ECG, lower systolic blood pressure and heart rate, a lower pH and a lower base excess on admission. Patients with diethyl-OPs required intubation significantly earlier and showed lower and more sustained inhibited activity of the plasma-cholinesterase on admission compared with patients ingesting dimethyl-OPs. Treatment with atropine and obidoxime was comparable between these groups and severity of poisoning, outcome, hemodynamics on admission, duration of mechanical ventilation and length of stay in the ICU did not significantly differ between the involved group of dimethyl- and diethyl-OPs. We conclude that the fatality rate in our patient cohort treated in a well-staffed and equipped ICU of a developed country is quite similarly high compared with the rate observed in developing countries. Patients died rather late when severe cholinergic crisis had mostly been overcome and death was therefore related to non-poison specific complications.
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Affiliation(s)
- Heidi Hrabetz
- Department of Clinical Toxicology, II. Medizinische Klinik, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 Munich, Germany
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Skeletal muscle IP3R1 receptors amplify physiological and pathological synaptic calcium signals. J Neurosci 2011; 31:15269-83. [PMID: 22031873 DOI: 10.1523/jneurosci.3766-11.2011] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Ca(2+) release from internal stores is critical for mediating both normal and pathological intracellular Ca(2+) signaling. Recent studies suggest that the inositol 1,4,5-triphosphate (IP(3)) receptor mediates Ca(2+) release from internal stores upon cholinergic activation of the neuromuscular junction (NMJ) in both physiological and pathological conditions. Here, we report that the type I IP(3) receptor (IP(3)R(1))-mediated Ca(2+) release plays a crucial role in synaptic gene expression, development, and neuromuscular transmission, as well as mediating degeneration during excessive cholinergic activation. We found that IP(3)R(1)-mediated Ca(2+) release plays a key role in early development of the NMJ, homeostatic regulation of neuromuscular transmission, and synaptic gene expression. Reducing IP(3)R(1)-mediated Ca(2+) release via siRNA knockdown or IP(3)R blockers in C2C12 cells decreased calpain activity and prevented agonist-induced acetylcholine receptor (AChR) cluster dispersal. In fully developed NMJ in adult muscle, IP(3)R(1) knockdown or blockade effectively increased synaptic strength at presynaptic and postsynaptic sites by increasing both quantal release and expression of AChR subunits and other NMJ-specific genes in a pattern resembling muscle denervation. Moreover, in two mouse models of cholinergic overactivity and NMJ Ca(2+) overload, anti-cholinesterase toxicity and the slow-channel myasthenic syndrome (SCS), IP(3)R(1) knockdown eliminated NMJ Ca(2+) overload, pathological activation of calpain and caspase proteases, and markers of DNA damage at subsynaptic nuclei, and improved both neuromuscular transmission and clinical measures of motor function. Thus, blockade or genetic silencing of muscle IP(3)R(1) may be an effective and well tolerated therapeutic strategy in SCS and other conditions of excitotoxicity or Ca(2+) overload.
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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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Li J, Ma Q, Xu S, Mu Y, Miao Y. Electrochemical Assay of Methyl Parathion in Homogeneous Reaction Using Water Soluble Films with Immobilized Acetylcholinesterase. J DISPER SCI TECHNOL 2011. [DOI: 10.1080/01932691003799928] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Thiermann H, Seeger T, Gonder S, Herkert N, Antkowiak B, Zilker T, Eyer F, Worek F. Assessment of neuromuscular dysfunction during poisoning by organophosphorus compounds. Chem Biol Interact 2010; 187:265-9. [DOI: 10.1016/j.cbi.2009.12.027] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Revised: 12/17/2009] [Accepted: 12/21/2009] [Indexed: 10/20/2022]
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Worek F, Aurbek N, Wille T, Eyer P, Thiermann H. Kinetic prerequisites of oximes as effective reactivators of organophosphate-inhibited acetylcholinesterase: a theoretical approach. J Enzyme Inhib Med Chem 2010; 26:303-8. [DOI: 10.3109/14756366.2010.504673] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany
| | - Nadine Aurbek
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany
| | - Timo Wille
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany
| | - Peter Eyer
- Walther-Straub-Institute of Pharmacology and Toxicology, Ludwig-Maximilians-University, Munich, Germany
| | - Horst Thiermann
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany
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Muscle force and acetylcholinesterase activity in mouse hemidiaphragms exposed to paraoxon and treated by oximes in vitro. Toxicology 2010; 272:46-51. [DOI: 10.1016/j.tox.2010.04.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 03/15/2010] [Accepted: 04/03/2010] [Indexed: 11/20/2022]
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Tropane alkaloid analysis by chromatographic and electrophoretic techniques: An update. J Chromatogr B Analyt Technol Biomed Life Sci 2010; 878:1391-406. [DOI: 10.1016/j.jchromb.2010.03.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 02/27/2010] [Accepted: 03/05/2010] [Indexed: 12/29/2022]
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