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Machamer JB, Vazquez-Cintron EJ, O'Brien SW, Kelly KE, Altvater AC, Pagarigan KT, Dubee PB, Ondeck CA, McNutt PM. Antidotal treatment of botulism in rats by continuous infusion with 3,4-diaminopyridine. Mol Med 2022; 28:61. [PMID: 35659174 PMCID: PMC9164507 DOI: 10.1186/s10020-022-00487-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 05/17/2022] [Indexed: 11/10/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) are highly potent, select agent toxins that inhibit neurotransmitter release at motor nerve terminals, causing muscle paralysis and death by asphyxiation. Other than post-exposure prophylaxis with antitoxin, the only treatment option for symptomatic botulism is intubation and supportive care until recovery, which can require weeks or longer. In previous studies, we reported the FDA-approved drug 3,4-diaminopyridine (3,4-DAP) reverses early botulism symptoms and prolongs survival in lethally intoxicated mice. However, the symptomatic benefits of 3,4-DAP are limited by its rapid clearance. Here we investigated whether 3,4-DAP could sustain symptomatic benefits throughout the full course of respiratory paralysis in lethally intoxicated rats. First, we confirmed serial injections of 3,4-DAP stabilized toxic signs and prolonged survival in rats challenged with 2.5 LD50 BoNT/A. Rebound of toxic signs and death occurred within hours after the final 3,4-DAP treatment, consistent with the short half-life of 3,4-DAP in rats. Based on these data, we next investigated whether the therapeutic benefits of 3,4-DAP could be sustained throughout the course of botulism by continuous infusion. To ensure administration of 3,4-DAP at clinically relevant doses, three infusion dose rates (0.5, 1.0 and 1.5 mg/kg∙h) were identified that produced steady-state serum levels of 3,4-DAP consistent with clinical dosing. We then compared dose-dependent effects of 3,4-DAP on toxic signs and survival in rats intoxicated with 2.5 LD50 BoNT/A. In contrast to saline vehicle, which resulted in 100% mortality, infusion of 3,4-DAP at ≥ 1.0 mg/kg∙h from 1 to 14 d after intoxication produced 94.4% survival and full resolution of toxic signs, without rebound of toxic signs after infusion was stopped. In contrast, withdrawal of 3,4-DAP infusion at 5 d resulted in re-emergence of toxic sign and death within 12 h, confirming antidotal outcomes require sustained 3,4-DAP treatment for longer than 5 d after intoxication. We exploited this novel survival model of lethal botulism to explore neurophysiological parameters of diaphragm paralysis and recovery. While neurotransmission was nearly eliminated at 5 d, neurotransmission was significantly improved at 21 d in 3,4-DAP-infused survivors, although still depressed compared to naïve rats. 3,4-DAP is the first small molecule to reverse systemic paralysis and promote survival in animal models of botulism, thereby meeting a critical treatment need that is not addressed by post-exposure prophylaxis with conventional antitoxin. These data contribute to a growing body of evidence supporting the use of 3,4-DAP to treat clinical botulism.
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Affiliation(s)
- James B Machamer
- U.S. Army Medical Research Institute of Chemical Defense, Gunpowder, MD, 21010, USA
- BASF, Research Triangle, Durham, NC, 27709, USA
| | | | - Sean W O'Brien
- U.S. Army Medical Research Institute of Chemical Defense, Gunpowder, MD, 21010, USA
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, 27101, USA
| | - Kyle E Kelly
- U.S. Army Medical Research Institute of Chemical Defense, Gunpowder, MD, 21010, USA
| | - Amber C Altvater
- U.S. Army Medical Research Institute of Chemical Defense, Gunpowder, MD, 21010, USA
| | - Kathleen T Pagarigan
- U.S. Army Medical Research Institute of Chemical Defense, Gunpowder, MD, 21010, USA
| | - Parker B Dubee
- U.S. Army Medical Research Institute of Chemical Defense, Gunpowder, MD, 21010, USA
| | - Celinia A Ondeck
- U.S. Army Medical Research Institute of Chemical Defense, Gunpowder, MD, 21010, USA
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, 27101, USA
| | - Patrick M McNutt
- U.S. Army Medical Research Institute of Chemical Defense, Gunpowder, MD, 21010, USA.
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, 27101, USA.
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Pirazzini M, Montecucco C, Rossetto O. Toxicology and pharmacology of botulinum and tetanus neurotoxins: an update. Arch Toxicol 2022; 96:1521-1539. [PMID: 35333944 PMCID: PMC9095541 DOI: 10.1007/s00204-022-03271-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 02/28/2022] [Indexed: 12/27/2022]
Abstract
Tetanus and botulinum neurotoxins cause the neuroparalytic syndromes of tetanus and botulism, respectively, by delivering inside different types of neurons, metalloproteases specifically cleaving the SNARE proteins that are essential for the release of neurotransmitters. Research on their mechanism of action is intensively carried out in order to devise improved therapies based on antibodies and chemical drugs. Recently, major results have been obtained with human monoclonal antibodies and with single chain antibodies that have allowed one to neutralize the metalloprotease activity of botulinum neurotoxin type A1 inside neurons. In addition, a method has been devised to induce a rapid molecular evolution of the metalloprotease domain of botulinum neurotoxin followed by selection driven to re-target the metalloprotease activity versus novel targets with respect to the SNARE proteins. At the same time, an intense and wide spectrum clinical research on novel therapeutics based on botulinum neurotoxins is carried out, which are also reviewed here.
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Affiliation(s)
- Marco Pirazzini
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131, Padova, Italy.,Centro Interdipartimentale di Ricerca di Miologia, CIR-Myo, University of Padova, Via U. Bassi 58/B, 35131, Padova, Italy
| | - Cesare Montecucco
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131, Padova, Italy. .,Institute of Neuroscience, National Research Council, Via Ugo Bassi 58/B, 35131, Padova, Italy.
| | - Ornella Rossetto
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131, Padova, Italy.,Centro Interdipartimentale di Ricerca di Miologia, CIR-Myo, University of Padova, Via U. Bassi 58/B, 35131, Padova, Italy.,Institute of Neuroscience, National Research Council, Via Ugo Bassi 58/B, 35131, Padova, Italy
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De Giglio L, Cortese F, Pennisi EM. Aminopiridines in the treatment of multiple sclerosis and other neurological disorders. Neurodegener Dis Manag 2020; 10:409-423. [PMID: 33054615 DOI: 10.2217/nmt-2020-0018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Symptomatic treatment has a great relevance for the management of patients with neurologic diseases, since it reduces disease burden and improves quality of life. Aminopyridines (APs) are a group of potassium (K+) channel blocking agents that exert their activity both at central nervous system level and on neuromuscular junction. This review describes the use of APs for the symptomatic treatment of neurological conditions. We will describe trials leading to the approval of the extended-release 4-aminopyridine for MS and evidence in support of the use in other neurological diseases.
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Affiliation(s)
- Laura De Giglio
- Department of Medicine, San Filippo Neri Hospital, Neurology Unit, Rome, Italy
| | - Francesca Cortese
- Department of Medicine, San Filippo Neri Hospital, Neurology Unit, Rome, Italy
| | - Elena Maria Pennisi
- Department of Medicine, San Filippo Neri Hospital, Neurology Unit, Rome, Italy
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Vazquez-Cintron E, Machamer J, Ondeck C, Pagarigan K, Winner B, Bodner P, Kelly K, Pennington MR, McNutt P. Symptomatic treatment of botulism with a clinically approved small molecule. JCI Insight 2020; 5:132891. [PMID: 31996484 DOI: 10.1172/jci.insight.132891] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 12/18/2019] [Indexed: 11/17/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) are potent neuroparalytic toxins that cause mortality through respiratory paralysis. The approved medical countermeasure for BoNT poisoning is infusion of antitoxin immunoglobulins. However, antitoxins have poor therapeutic efficacy in symptomatic patients; thus, there is an urgent need for treatments that reduce the need for artificial ventilation. We report that the US Food and Drug Administration-approved potassium channel blocker 3,4-diaminopyridine (3,4-DAP) reverses respiratory depression and neuromuscular weakness in murine models of acute and chronic botulism. In ex vivo studies, 3,4-DAP restored end-plate potentials and twitch contractions of diaphragms isolated from mice at terminal stages of BoNT serotype A (BoNT/A) botulism. In vivo, human-equivalent doses of 3,4-DAP reversed signs of severe respiratory depression and restored mobility in BoNT/A-intoxicated mice at terminal stages of respiratory collapse. Multiple-dosing administration of 3,4-DAP improved respiration and extended survival at up to 5 LD50 BoNT/A. Finally, 3,4-DAP reduced gastrocnemius muscle paralysis and reversed respiratory depression in sublethal models of serotype A-, B-, and E-induced botulism. These findings make a compelling argument for repurposing 3,4-DAP to symptomatically treat symptoms of muscle paralysis caused by botulism, independent of serotype. Furthermore, they suggest that 3,4-DAP is effective for a range of botulism symptoms at clinically relevant time points.
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Bradford AB, Machamer JB, Russo TM, McNutt PM. 3,4-diaminopyridine reverses paralysis in botulinum neurotoxin-intoxicated diaphragms through two functionally distinct mechanisms. Toxicol Appl Pharmacol 2018; 341:77-86. [PMID: 29366638 DOI: 10.1016/j.taap.2018.01.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 01/15/2018] [Accepted: 01/18/2018] [Indexed: 01/11/2023]
Abstract
Botulinum neurotoxins (BoNTs) are exceedingly potent neurological poisons that prevent neurotransmitter release from peripheral nerve terminals by cleaving presynaptic proteins required for synaptic vesicle fusion. The ensuing neuromuscular paralysis causes death by asphyxiation. Although no antidotal treatments exist to block toxin activity within the nerve terminal, aminopyridine antagonists of voltage-gated potassium channels have been proposed as symptomatic treatments for botulism toxemia. However, clinical evaluation of aminopyridines as symptomatic treatments for botulism has been inconclusive, in part because mechanisms responsible for reversal of paralysis in BoNT-poisoned nerve terminals are not understood. Here we measured the effects of 3,4-diaminopyridine (DAP) on phrenic nerve-elicited diaphragm contraction and end-plate potentials at various times after intoxication with BoNT serotypes A, B, or E. We found that DAP-mediated increases in quantal content promote neurotransmission from intoxicated nerve terminals through two functionally distinguishable mechanisms. First, DAP increases the probability of neurotransmission at non-intoxicated release sites. This mechanism is serotype-independent, becomes less effective as nerve terminals become progressively impaired, and remains susceptible to ongoing intoxication. Second, DAP elicits persistent production of toxin-resistant endplate potentials from nerve terminals fully intoxicated by BoNT/A, but not serotypes B or E. Since this effect appears specific to BoNT/A intoxication, we propose that DAP treatment enables BoNT/A-cleaved SNAP-25 to productively engage in fusogenic release by increasing the opportunity for low-efficiency fusion events. These findings have important implications for DAP as a botulism therapeutic by defining conditions under which DAP may be clinically effective in reversing botulism symptoms.
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Affiliation(s)
- Aaron B Bradford
- Department of Neuroscience, United States Army Medical Research Institute of Chemical Defense, 2900 Ricketts Point Road, Gunpowder, MD 21010, USA
| | - James B Machamer
- Department of Neuroscience, United States Army Medical Research Institute of Chemical Defense, 2900 Ricketts Point Road, Gunpowder, MD 21010, USA
| | - Trisha M Russo
- Department of Neuroscience, United States Army Medical Research Institute of Chemical Defense, 2900 Ricketts Point Road, Gunpowder, MD 21010, USA
| | - Patrick M McNutt
- Department of Neuroscience, United States Army Medical Research Institute of Chemical Defense, 2900 Ricketts Point Road, Gunpowder, MD 21010, USA.
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Presynaptic Deficits at Neuromuscular Junctions: A Specific Cause and Potential Target of Axonal Neuropathy in Type 2 Charcot-Marie-Tooth Disease. J Neurosci 2018; 36:8067-9. [PMID: 27488627 DOI: 10.1523/jneurosci.1515-16.2016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 06/23/2016] [Indexed: 11/21/2022] Open
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Baskaran P, Thyagarajan B. Acute and chronic effects of botulinum neurotoxin a on the mammalian neuromuscular junction. Muscle Nerve 2014; 50:206-15. [PMID: 24218344 DOI: 10.1002/mus.24119] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 10/30/2013] [Accepted: 11/07/2013] [Indexed: 11/07/2022]
Abstract
INTRODUCTION Botulinum neurotoxin A (BoNT/A) cleaves SNAP-25 and inhibits acetylcholine (ACh) release at the neuromuscular junctions (NMJ) to cause neuroparalysis. Previous reports indicate a dyssynchrony between the inhibitory effect of BoNT/A on ACh release and SNAP-25 cleavage. METHODS We tested the in vitro (acute; 90 min) and in vivo (chronic; 12 h) effects of BoNT/A on stimulus-evoked ACh release (SEAR), twitch tension, and SNAP-25 cleavage in isolated extensor digitorum longus (EDL) nerve-muscle preparations (NMP). RESULTS In vitro or in vivo BoNT/A poisoning inhibited SEAR and twitch tension. Conversely, SNAP-25 cleavage and inhibition of spontaneous release frequency were observed only in NMP poisoned with BoNT/A in vivo. Moreover, chronic treatment of BoNT/A inhibited ionomycin stimulated Ca(2+) signals in Neuro 2a cells. CONCLUSIONS These results demonstrate that the inhibition of SEAR precedes SNAP-25 cleavage and suggest involvement of a more complex mechanism for the inhibitory effect of BoNT/A at the NMJ.
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Affiliation(s)
- Padmamalini Baskaran
- School of Pharmacy, 1000 East University Avenue, University of Wyoming, Laramie, Wyoming, 82071
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Sheridan RE, Deshpande SS, Smith T. Comparison of in vivo and in vitro mouse bioassays for botulinum toxin antagonists. J Appl Toxicol 1999. [DOI: 10.1002/(sici)1099-1263(199912)19:1+3.0.co;2-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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10
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Abstract
Botulinum neurotoxins (BoNT) are thought to enter cells through endocytotic vesicles where acidification is required for release of these toxins into the cytoplasm. Two ionophores, nigericin and monensin, that increase membrane permeability to H+ and K+ or H+, Na+ and K+, respectively, block vesicle acidification by acting as H+ shunts to neutralize pH gradients. Nanomolar concentrations of nigericin or monensin delayed development of blockade in BoNT-A or BoNT-B treated muscles two-to threefold over onset times in unprotected muscles. However, higher concentrations of the ionophores directly blocked synapses. Thus, nigericin and monensin could delay onset of BoNT paralysis only over a narrow range of concentrations.
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Affiliation(s)
- R E Sheridan
- Neurotoxicology Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010, USA
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Capacio BR, Byers CE, Matthews RL, Chang FC. A method for determining 4-aminopyridine in plasma: pharmacokinetics in anaesthetized guinea pigs after intravenous administration. Biomed Chromatogr 1996; 10:111-6. [PMID: 8792860 DOI: 10.1002/(sici)1099-0801(199605)10:3<111::aid-bmc569>3.0.co;2-e] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
An HPLC assay has been developed to measure 4-aminopyridine (4-AP) in guinea pig plasma. For the assay, all plasma samples (50 microL) were microfiltered following the addition of an internal standard (3,4-diaminopyridine). Filtrates (10 microL) were directly injected into a spherical silica column (100 x 2.1 mm; 5 microns); detection was achieved at 266 nm. Standard curves had correlation coefficients ranging from 0.9923 to 0.9992 and coefficients of variation expressed as a percentage (% CV) of below 8%. Precision was expressed as between-day and within-day variability of five test sample concentrations. Between-day % CV ranged from 4.0 to 6.5%. Within-day % CV ranged from 3.6 to 6.9%. Accuracy was assessed by examining expected within-day test sample concentrations against calculated concentrations; per cent errors were all below 10%. Stability studies demonstrated % CV below 5% after repeated freezing. The method was employed to study the pharmacokinetics of 4-AP after intravenous administration to anaesthetized guinea pigs. Serial blood samples (150 microL) were collected at predetermined time intervals up to 4 h post-4-AP (2 mg/kg, i.v.) administration. 4-AP demonstrated a biexponential decline in the plasma-concentration curve as a function of time indicating a two compartment model for this drug. Selected mean pharmacokinetic parameter estimates were alpha-half-life, 0.37 min; beta-half-life (biological half-life) for terminal slope, 109 min; and volume of distribution at steady state, 1036.18 mL/kg. 4-AP was found to rapidly and extensively partition into a peripheral tissue compartment and demonstrated a relatively long biological half-life. The findings from the current pharmacokinetic experiments support the pharmacology of 4-AP in its role for reversing saxitoxin (STX)- and tetrodotoxin (TTX)-induced diaphragmatic failure in terms of onset of action and duration of effect in anaesthetized guinea pigs.
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Affiliation(s)
- B R Capacio
- US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland 21010-5425, USA
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12
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Adler M, Macdonald DA, Sellin LC, Parker GW. Effect of 3,4-diaminopyridine on rat extensor digitorum longus muscle paralyzed by local injection of botulinum neurotoxin. Toxicon 1996; 34:237-49. [PMID: 8711757 DOI: 10.1016/0041-0101(95)00127-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The actions of the K+ channel blocker, 3,4-diaminopyridine (3,4-DAP), were studied in the rat extensor digitorum longus (EDL) muscle following local inhibition of neuromuscular transmission by botulinum neurotoxin (BoNT). Local paralysis of the EDL muscle was induced by s.c. injections of BoNT serotypes A, B, E or F over the anterior tibialis muscle. One to 14 days later, the rats were anesthetized with urethane, and isometric twitch tensions following stimulation of the peroneal nerve were measured in situ. Muscles were paralyzed within 24 hr of administration of 5 mouse LD50 units (U) of BoNT/A and remained inhibited for the entire 14-day period of observation. Similar levels of inhibition, but of shorter duration, were observed after local injection of 20 U of BoNT/E, 10(4) U of BoNT/B or 20 U of BoNT/F. 3,4-DAP (4 mg/kg, i.v.) potentiated twitch tensions markedly in BoNT/A intoxicated muscle. The increase in tension developed rapidly (halftime = 5.81 +/- 0.6 min), persisted for approximately 1 hr, then decayed slowly with a halftime of 25.2 +/- 4.6 min. Subsequent administration of 3,4-DAP restored tensions to the original maxima, and this procedure could be repeated up to eight times with no decrement. The action of 3,4-DAP was comparable when given 1, 2, 3 or 7 days after BoNT/A and enhanced when administered 14 days after toxin injection. 3,4-DAP was less effective in reversing BoNT/E-induced muscle paralysis and nearly ineffective in antagonizing the paralytic actions of BoNT/B or BoNT/F. The results indicate that 3,4-DAP is of benefit in BoNT/A and BoNT/E intoxication, but is of marginal value after exposure to serotypes B and F.
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Affiliation(s)
- M Adler
- Neurotoxicology Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA
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Sheridan RE, Deshpande SS. Interactions between heavy metal chelators and botulinum neurotoxins at the mouse neuromuscular junction. Toxicon 1995; 33:539-49. [PMID: 7570639 DOI: 10.1016/0041-0101(94)00185-b] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Exposure of isolated mouse hemidiaphragms to botulinum neurotoxins, 0.1 nM BoNT-A or BoNT-B, at 36 degrees C reduced nerve-elicited peak isometric twitch tension to 50% of control values at 55 min (BoNT-A) to 68 min (BoNT-B) after application. Either coincubation of BoNT with the heavy metal chelator TPEN, preincubation with TPEN followed by BoNT, or application of TPEN after BoNT but before neuromuscular block, delayed the onset of muscle failure in a dose-dependent manner by up to five-fold. TPEN doses between 2 and 10 microM were required to antagonize significantly the muscle block produced by BoNT, and the delay in onset was maximal between 10 and 50 microM TPEN. Treatment of muscles with a Zn(2+)-TPEN coordination complex, rather than TPEN alone, eliminated any beneficial effects of TPEN on BoNT intoxication, indicating that these effects were mediated by chelation of Zn2+. Other metal chelators that were not as membrane permeant as TPEN were ineffective in delaying BoNT paralysis, suggesting that TPEN acts by chelating intraterminal Zn2+. In the absence of BoNT, TPEN caused a dose-dependent increase in nerve-elicited twitch tension with a half-maximal concentration at 8 microM. There was no corresponding change in twitches from direct electrical stimulation of the muscle. After BoNT (A or B serotype) had reduced the muscle twitch by 20 to 70%, however, subsequent application of TPEN rapidly depressed nerve-elicited twitches. The shift from potentiation to depression after BoNT treatment suggests that presynaptic vesicle mobilization and/or release involve Zn(2+)-dependent enzymes and that BoNTs interact with these enzyme pathways.
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Affiliation(s)
- R E Sheridan
- Neurotoxicology Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA
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Abstract
Toxigenic clostridia belonging to 13 recognized species are discussed in this review. Each species or group of organisms is, in general, introduced by presenting the historical aspects of its discovery by early investigators of human and animal diseases. The diseases caused by each species or group are described and usually discussed in relation to the toxins involved in the pathology. Morphological and physiological characteristics of the organisms are described. Finally, the toxins produced by each organism are listed, with a presentation of their biological activities and physical and biochemical characteristics. The complete amino acid sequences for some are known, and some of the genes have been cloned. The term toxin is used loosely to include the various antigenic protein products of these organisms with biological and serological activities which have served as distinguishing characteristics for differentiation and classification. Some of these factors are not truly toxic and have no known role in pathogenicity. Some of the interesting factors common to more than one species or group are the following: neurotoxins, lethal toxins, lecithinases, oxygen-labile hemolysins, binary toxins, and ADP-ribosyltransferases. Problems in bacterial nomenclature and designation of biologically active factors are noted.
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Simpson LL, Schmidt JJ, Middlebrook JL. Isolation and characterization of the Botulinum neurotoxins. Methods Enzymol 1988; 165:76-85. [PMID: 3068491 DOI: 10.1016/s0076-6879(88)65015-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Abstract
Clostridium botulinum neurotoxins inhibit acetylcholine release at neuromuscular junctions. Agents stimulating neurotransmitter efflux, such as 3,4-diaminopyridine (3,4-DAP), could be useful for botulism therapy. Treatment with 3,4-DAP (8 mg/kg hourly, beginning 3 hr after toxin injection) failed to increase the survival times of mice receiving 10, 20 or 40 LD50 type C, but did prolong the survival of those receiving 20 LD50 type A. This difference in 3,4-DAP efficacy may reflect variations in the molecular mechanism of action of types A and C botulinum neurotoxins.
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Affiliation(s)
- L S Siegel
- Pathology Division, U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD 21701
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