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Sample records for obidoxime trimedoxime hi-6

  1. Acetylcholinesterase Reactivators (HI-6, Obidoxime, Trimedoxime, K027, K075, K127, K203, K282): Structural Evaluation of Human Serum Albumin Binding and Absorption Kinetics

    PubMed Central

    Zemek, Filip; Zdarova, Jana Karasova; Sepsova, Vendula; Kuca, Kamil

    2013-01-01

    Acetylcholinesterase (AChE) reactivators (oximes) are compounds predominantly targeting the active site of the enzyme. Toxic effects of organophosphates nerve agents (OPNAs) are primarily related to their covalent binding to AChE and butyrylcholinesterase (BChE), critical detoxification enzymes in the blood and in the central nervous system (CNS). After exposure to OPNAs, accumulation of acetylcholine (ACh) overstimulates receptors and blocks neuromuscular junction transmission resulting in CNS toxicity. Current efforts at treatments for OPNA exposure are focused on non-quaternary reactivators, monoisonitrosoacetone oximes (MINA), and diacylmonoxime reactivators (DAM). However, so far only quaternary oximes have been approved for use in cases of OPNA intoxication. Five acetylcholinesterase reactivator candidates (K027, K075, K127, K203, K282) are presented here, together with pharmacokinetic data (plasma concentration, human serum albumin binding potency). Pharmacokinetic curves based on intramuscular application of the tested compounds are given, with binding information and an evaluation of structural relationships. Human Serum Albumin (HSA) binding studies have not yet been performed on any acetylcholinesterase reactivators, and correlations between structure, concentration curves and binding are vital for further development. HSA bindings of the tested compounds were 1% (HI-6), 7% (obidoxime), 6% (trimedoxime), and 5%, 10%, 4%, 15%, and 12% for K027, K075, K127, K203, and K282, respectively. PMID:23917882

  2. A comparison of reactivating and therapeutic efficacy of bispyridinium acetylcholinesterase reactivator KR-22934 with the oxime K203 and commonly used oximes (obidoxime, trimedoxime, HI-6) in tabun-poisoned rats and mice.

    PubMed

    Kassa, Jiri; Karasova, Jana Zdarova; Pavlikova, Ruzena; Musilek, Kamil; Kuca, Kamil; Bajgar, Jiri; Jung, Young-Sik

    2011-03-01

    The potency of bispyridinium acetylcholinesterase reactivator KR-22934 in reactivating tabun-inhibited acetylcholinesterase and reducing tabun-induced lethal toxic effects was compared with the oxime K203 and commonly used oximes. Studies determining percentage of reactivation of tabun-inhibited blood and tissue acetylcholinesterase in rats showed that the reactivating efficacy of KR-22934 was slightly higher than the reactivating efficacy of K203 and roughly corresponded to the reactivating efficacy of obidoxime and trimedoxime in blood and diaphragm. On the other hand, the oxime KR-22934 was not able to reactivate tabun-inhibited acetylcholinesterase in the brain. The therapeutic efficacy of all oximes studied approximately corresponded to their reactivating efficacy. Based on the results, one can conclude that the oxime KR-22934 is not suitable for the replacement of commonly used oximes for the antidotal treatment of tabun poisoning in spite of its potency to reactivate tabun-inhibited acetylcholinesterase in the peripheral compartment (blood, diaphragm).

  3. A comparison of the neuroprotective efficacy of individual oxime (HI-6) and combinations of oximes (HI-6+trimedoxime, HI-6+K203) in soman-poisoned rats.

    PubMed

    Kassa, Jiri; Karasova, Jana Zdarova; Tesarova, Sandra

    2011-07-01

    The ability of two combinations of oximes (HI-6+trimedoxime, HI-6+K203) to reduce soman-induced acute neurotoxic signs and symptoms was compared with the neuroprotective efficacy of the oxime HI-6 alone, using a functional observational battery. Soman-induced neurotoxicity and the neuroprotective effects of HI-6 alone and HI-6 combined with trimedoxime or K203 in rats poisoned with soman at a sublethal dose (90 μg/kg intramuscularly, i.m.; 80% of LD₅₀ value) were monitored by the functional observational battery at 24 hours following soman administration. The results indicate that both tested oxime mixtures combined with atropine were able to allow soman-poisoned rats to survive 24 hours following soman challenge, while 4 nontreated soman-poisoned rats and 1 soman-poisoned rat treated with oxime HI-6 alone combined with atropine died within 24 hours following soman poisoning. While the oxime HI-6 alone combined with atropine treatment was able to eliminate a few soman-induced neurotoxic signs and symptoms, both oxime mixtures showed higher neuroprotective efficacy in soman-poisoned rats. Especially, the combination of HI-6 with trimedoxime was able to eliminate most soman-induced neurotoxic signs and symptoms and markedly reduce acute neurotoxicity of soman in rats. Thus, both tested mixtures of oximes combined with atropine were able to increase the neuroprotective effectiveness of antidotal treatment of acute soman poisonings, compared to the individual oxime.

  4. Reactivation of nerve agent-inhibited human acetylcholinesterase by obidoxime, HI-6 and obidoxime+HI-6: Kinetic in vitro study with simulated nerve agent toxicokinetics and oxime pharmacokinetics.

    PubMed

    Worek, Franz; Koller, Marianne; Thiermann, Horst; Wille, Timo

    2016-03-28

    Despite extensive research for decades no effective broad-spectrum oxime for the treatment of poisoning by a broad range of nerve agents is available. Previous in vitro and in vivo data indicate that the combination of in service oximes could be beneficial. To investigate the ability of obidoxime, HI-6 and the combination of both oximes to reactivate inhibited human AChE in the presence of sarin, cyclosarin or tabun we adopted a dynamic in vitro model with real-time and continuous determination of AChE activity to simulate inhalation nerve agent exposure and intramuscular oxime administration. The major findings of this kinetic study are that the extent and velocity of reactivation is dependent on the nerve agent and the oxime-specific reactivating potency. The oxime-induced reactivation of inhibited human AChE in the presence of nerve agents is markedly impaired and the combination of obidoxime and HI-6 had no additive effect but could broaden the spectrum. In conclusion, these data indicate that a combination of obidoxime and HI-6 would be beneficial for the treatment of poisoning by a broad spectrum of nerve agents and could present an interim solution until more effective and broad-spectrum reactivators are available.

  5. A comparison of the reactivating and therapeutic efficacy of two novel bispyridinium oximes (K727, K733) with the oxime HI-6 and obidoxime in sarin-poisoned rats and mice.

    PubMed

    Kassa, Jiri; Sepsova, Vendula; Matouskova, Lenka; Horova, Anna; Musilek, Kamil

    2015-03-01

    The ability of two novel bispyridinium oximes K727 and K733 and currently available oximes (HI-6, obidoxime) to reactivate sarin-inhibited acetylcholinesterase and to reduce acute toxicity of sarin was evaluated. To investigate the reactivating efficacy of the oximes, the rats were administered intramuscularly with atropine and oximes in equitoxic doses corresponding to 5% of their LD50 values at 1 min after the intramuscular administration of sarin at a dose of 24 µg/kg (LD50). The activity of acetylcholinesterase was measured at 60 min after sarin poisoning. The LD50 value of sarin in non-treated and treated mice was assessed using probit-logarithmical analysis of death occurring within 24 h after intramuscular administration of sarin at five different doses. In vivo determined percentage of reactivation of sarin-inhibited rat blood, diaphragm and brain acetylcholinesterase showed that the potency of both novel oximes K727 and K733 to reactivate sarin-inhibited acetylcholinesterase roughly corresponds to the reactivating efficacy of obidoxime. On the other hand, the oxime HI-6 was found to be the most efficient reactivator of sarin-inhibited acetylcholinesterase. While the oxime HI-6 was able to reduce the acute toxicity of sarin >3 times, both novel oximes and obidoxime decreased the acute toxicity of sarin <2 times. Based on the results, we can conclude that the reactivating and therapeutic efficacy of both novel oximes K727 and K733 is significantly lower compared to the oxime HI-6 and, therefore, they are not suitable for the replacement of the oxime HI-6 for the antidotal treatment of acute sarin poisoning.

  6. Photostability of antidotal oxime HI-6, impact on drug development.

    PubMed

    Bogan, Reinhard; Worek, Franz; Koller, Marianne; Klaubert, Bernd

    2012-01-01

    HI-6 exhibits superior efficacy in the therapy of intoxication by different highly toxic organophosphorus nerve agents. Therefore HI-6 is a promising candidate for the development of new antidotes against nerve agents. For ethical and safety reasons antidotes containing HI-6 should get marketing authorization. Active pharmaceutical ingredients of medicinal products have to fulfil regulatory conditions in terms of purity and stability. Photostability is an essential parameter in this testing strategy. HI-6 was tested under conditions of ICH Q1B 'Photostability testing of new drug substances and products'. The data showed a marked degradation of HI-6 after exposure to daylight. The mechanism of degradation could be detected as photoisomerism. The light burden dependent rate of photoisomerism was followed quantitatively. Based on these quantitative results on the amount of light induced isomeric product a pharmacological qualification was made. A standardized in vitro test showed a decreased ability of light exposed HI-6 to reactivate sarin- and paraoxon-inhibited human acetylcholinesterase. These results have an impact on the further development of antidotes containing HI-6, as light protection will probably be necessary during handling, packaging, storage and application.

  7. Neurobehavioral effects of the pyridinium aldoxime cholinesterase reactivator HI-6.

    PubMed

    Liu, W F; Shih, J H

    1990-01-01

    A series of neurobehavioral testing procedures was used to evaluate the behavioral effects of the pyridinium aldoxime cholinesterase reactivator HI-6 in male Sprague-Dawley rats. These procedures were fixed-ratio (FR) responding, shuttle-box conditioned avoidance response (CAR), conditioned taste aversion (CTA), drinking behavior, open-field exploratory behavior, negative geotaxis, and wire suspension time. Dose-response studies of HI-6 at dose-levels of 25, 50 and 100 mg/kg, or saline (IP) were evaluated. HI-6 disrupted FR responding in a dose-dependent fashion, with significant effects occurring at doses of 50 and 100 mg/kg. The pattern of disruption was characterized by extended periods of nonresponding having an abrupt onset and offset. HI-6 produced CTA in a dose-related manner, with significant effects at doses equal to those that disrupted FR performance. HI-6 did not alter CAR, drinking motivation, exploratory behavior, negative geotaxis, or wire suspension time. These data suggest that there may be a commonality in the underlying mechanism(s) for the disruption in FR performance and the induction of the CTA. This mechanism may relate to the presumed drug-induced adverse internal state inducing the CTA.

  8. Application of kinetic-based computer modelling to evaluate the efficacy of HI 6 in percutaneous VX poisoning.

    PubMed

    Aurbek, N; Thiermann, H; Szinicz, L; Eyer, P; Worek, F

    2006-07-01

    The rife use of organophosphorus compounds (OP) as pesticides and the exertion of highly toxic OP-type chemical warfare agents (nerve agents) during military conflicts and terrorist attacks in the past emphasize the necessity of the development of effective therapeutic countermeasures. Presently, standard treatment of poisoning by OP includes administration of atropine as an antimuscarinic agent and of oximes, e.g. obidoxime or pralidoxime, as reactivators of OP-inhibited acetylcholinesterase (AChE), but is considered to be rather ineffective with certain nerve agents. The evaluation of new oximes as antidotes is only possible by implementation of animal experiments for ethical reasons and therefore complicated by a limited extrapolation of animal data to humans due to marked species differences. A computer simulation based on combination of AChE kinetic data (inhibition, reactivation, aging) with OP toxicokinetics and oxime pharmacokinetics allows the calculation of AChE activities at different scenarios and may facilitate to define effective oxime concentrations and to optimize oxime dosage in OP poisoning. On the base of species-specific kinetic data this model was used to calculate AChE activities in humans and pigs after percutaneous exposure to 5 x LD50 VX and treatment with HI 6. Due to marked species differences between human and pig AChE the HI 6 dose that is necessary to cause a comparable reactivation of VX-inhibited pig AChE is conspicuously higher. Hence, designing animal experiments with the aid of computer modeling may reduce the number of animal experiments and allow a more reliable extrapolation of animal data to humans.

  9. Hyaluronidase: its effects on HI-6 dichloride and dimethanesulphonate pharmacokinetic profile in pigs.

    PubMed

    Karasova, Jana Zdarova; Pavlik, Michal; Chladek, Jaroslav; Jun, Daniel; Kuca, Kamil

    2013-07-01

    Pigs were administered intramuscularly molar equivalents of HI-6 salts (HI-6 dichloride 10.71 mg/kg and HI-6 DMS 13.59 mg/kg) either with or without hyaluronidase (60 U/kg). Hyaluronidase is supposed to increase tissue permeability and diminishes discomfort caused by the intramuscular injection. Doses of HI-6 salts corresponded with standard HI-6 dichloride dose in one autoinjector (500 mg) and were recalculated for 1 kg of body weight. According to the results, both HI-6 salts applied in combination with hyaluronidase had increased tissue absorption and improved pharmacokinetic profile. The Cmax was significantly higher in case of HI-6 DMS plus hyaluronidase (29.6 ± 2.98 μg/ml) administration increase compared to HI-6 DMS (23.8 ± 3.04 μg/ml) and HI-6 dichloride (19.0 ± 0.93 μg/ml); both without hyaluronidase. Bioavailability calculated as AUCtotal (HI-6 DMS with hyaluronidase, 4,119 ± 647 min μg/ml) was also significantly higher compared to HI-6 DMS (2,259 ± 329 min μg/ml) and HI-6 dichloride (1,969 ± 254 min μg/ml); both without hyaluronidase. The results suggest that administration of HI-6 salt with higher solubility is the first step in the improvement of application strategy, but use some substances with spreading effect (hyaluronidase) may also leads to better absorption and better bioavailability. Improved bioavailability could to go hand in hand with increased effectiveness of therapy without the need of multiple autoinjector applications.

  10. Dose-response effects of atropine and HI-6 treatment of organophosphorus poisoning in guinea pigs

    SciTech Connect

    Koplovitz, I.; Menton, R.; Matthews, C.; Shutz, M.; Nalls, C.

    1995-12-31

    H1-6 (1-2-hydrnxyiminomethyl-1 pyridino-3-(4-carbameyl- 1--pyddino)-2- oxaprnpane dichioride) has been evaluated as an oxime alternative to pralidoxime, and toxogonin in the treatment of organophosphorus (OP) poisoning. The dose response effects of atropine (ATR) and HI-6 were investigated to more fully explore the interaction of these compounds in the treatment of OP poisoning. ATR, HI-6 and various combinations of the two drugs were evaluated against lethal poisoning by soman (GD) and tabun (GA) in guinea pigs. The effect of adjunctive diazepam treatment on the efficacy of atropine and HI-6 against soman was also investigated. Animals of either sex were challenged s.c. with OP and treated i.m. 1 min later with ATR and/or HI-6. When used, diazepam was injected immediately after ATR+HI6. LD50s of each treatment were calculated from probit models based on 24-hour survival against 5 levels of nerve agent and 6 animals per challenge level. A protective index (PI) was calculated by dividing the nerve agent LD50 in the presence of treatment by the LD50 in the absence of treatment. Treatment with HI-6 alone had little effect on the toxicity of either OP. Treatment with ATR alone was more effective than HI-6 alone and was significantly more effective against soman than against tabun. When used in combination atropine and HI-6 had a strong synergistic effect against both agents. The dose of atropine used with HI-6 was critical in determining the efficacy of HI-6 against either agent. The slopes of the dose-lethality curves were minimally affected by the dose of ATR or HI-6. Adjunctive treatment with diazepam enhanced the efficacy of HI-6 and atropine against soman.

  11. Dose-response effects of atropine and HI-6 treatment of organophosphorus poisoning in guinea pigs.

    PubMed

    Koplovitz, I; Menton, R; Matthews, C; Shutz, M; Nalls, C; Kelly, S

    1995-01-01

    HI-6 (1-2-hydroxyiminomethyl-1-pyridino-3-(4-carbamoyl-1-pyridino -2- oxapropane dichloride) has been evaluated as an oxime alternative to pralidoxime, and toxogonin in the treatment of organophosphorus (OP) poisoning. The dose response effects of atropine (ATR) and HI-6 were investigated to more fully explore the interaction of these compounds in the treatment of OP poisoning. ATR, HI-6 and various combinations of the two drugs were evaluated against lethal poisoning by soman (GD) and tabun (GA) in guinea pigs. The effect of adjunctive diazepam treatment on the efficacy of atropine and HI-6 against soman was also investigated. Animals of either sex were challenged s.c. with OP and treated i.m. 1 min later with ATR and/or HI-6. When used, diazepam was injected immediately after ATR+HI6. LD50s of each treatment were calculated from probit models based on 24-hour survival against 5 levels of nerve agent and 6 animals per challenge level. A protective index (PI) was calculated by dividing the nerve agent LD50 in the presence of treatment by the LD50 in the absence of treatment. Treatment with HI6 alone had little effect on the toxicity of either OP. Treatment with ATR alone was more effective than HI-6 alone and was significantly more effective against soman than against tabun. When used in combination atropine and HI-6 had a strong synergistic effect against both agents. The dose of atropine used with HI-6 was critical in determining the efficacy of HI-6 against either agent. The slopes of the dose-lethality curves were minimally affected by the dose of ATR or HI-6. Adjunctive treatment with diazepam enhanced the efficacy of HI-6 and atropine against soman. It is concluded that 1) ATR has a large effect on the efficacy of HI-6 against OP poisoning, 2) the dose of ATR must be carefully selected in studies investigating the efficacy of HI-6 against OP poisoning, 3) the effective dose of ATR in the guinea pig is approximately 16 mg/kg, and 4) diazepam is a useful

  12. Acetylcholine content in the brain of rats treated with paraoxon and obidoxime

    PubMed Central

    Milošević, M. P.

    1970-01-01

    1. The effect of obidoxime on the rise in brain acetylcholine caused by the anticholinesterase paraoxon was studied in the rat. 2. In animals poisoned with a sublethal dose of paraoxon and thereafter treated with obidoxime the levels of both “free” and total brain acetylcholine were practically the same as those in rats injected with paraoxon only. 3. After poisoning with doses of paraoxon which are lethal unless an oxime is also given, the total acetylcholine in the brain of obidoxime-protected rats continued to accumulate, reaching a peak 2 h after injection of paraoxon. At this time no signs of central effects such as convulsions or tremor were seen. 4. Atropine, given 30 min before paraoxon, markedly reduced the rise in total brain acetylcholine seen when the anticholinesterase is given alone. 5. In rats pretreated with atropine and obidoxime excessive doses of paraoxon which are lethal in the absence of the antidotes produced a rise in total brain acetylcholine which was directly proportional to the dose of paraoxon administered. PMID:5485148

  13. The Organophosphate Paraoxon and Its Antidote Obidoxime Inhibit Thrombin Activity and Affect Coagulation In Vitro

    PubMed Central

    Golderman, Valery; Shavit-Stein, Efrat; Tamarin, Ilia; Rosman, Yossi; Shrot, Shai; Rosenberg, Nurit

    2016-01-01

    Organophosphates (OPs) are potentially able to affect serine proteases by reacting with their active site. The potential effects of OPs on coagulation factors such as thrombin and on coagulation tests have been only partially characterized and potential interactions with OPs antidotes such as oximes and muscarinic blockers have not been addressed. In the current study, we investigated the in vitro interactions between coagulation, thrombin, the OP paraoxon, and its antidotes obidoxime and atropine. The effects of these substances on thrombin activity were measured in a fluorescent substrate and on coagulation by standard tests. Both paraoxon and obidoxime but not atropine significantly inhibited thrombin activity, and prolonged prothrombin time, thrombin time, and partial thromboplastin time. When paraoxon and obidoxime were combined, a significant synergistic effect was found on both thrombin activity and coagulation tests. In conclusion, paraoxon and obidoxime affect thrombin activity and consequently alter the function of the coagulation system. Similar interactions may be clinically relevant for coagulation pathways in the blood and possibly in the brain. PMID:27689805

  14. In vitro and in vivo genotoxicity assessment of HI-6 dimethanesulfonate/oxime.

    PubMed

    Nakab, Lauren; Bardot, Isabelle; Bardot, Sébastien; Simar, Sophie; Marzin, Daniel; Nesslany, Fabrice

    2014-03-01

    Organophosphate compounds, which induce organophosphate poisoning, were originally used as pesticides. But this type of product has also been used as warfare nerve agent like sarin, soman, Russian VX, or tabun. HI-6-dimethanesulfonate is a salt of the oxime HI-6 used in the treatment of nerve-agent poisoning. It is known to be the best re-activator component of inactivated acetyl cholinesterase. HI-6-dimethanesulfonate has shown a higher level of solubility with similar potency to reactivate acetyl cholinesterase and a similar pharmacokinetics profile compared with HI-6 dichloride. HI-6 dimethanesulfonate was tested for its mutagenic and genotoxic potential by use of the standard ICH S2R (1) battery for the evaluation of pharmaceuticals. HI-6-dimethanesulfonate was mutagenic in the Ames test only in the presence of metabolic activation. In the mutation assay at the Tk locus in L5178Y mouse-lymphoma cells, HI-6-dimethanesulfonate showed mutagenic activity both with and without metabolic activation, with a significant increase in small colonies. The effects were in favour of a clastogenic activity. It was concluded that the compound was mutagenic and possibly clastogenic in vitro. In contrast, the in vivo micronucleus test in rat bone-marrow did not demonstrate any genotoxic activity and the Comet assay performed in rat liver did not show any statistically or biologically significant increases in DNA strand-breaks. The results of both in vivo studies performed on two different organs with two endpoints are sufficient to conclude the absence of a genotoxic hazard in vivo and to consider that there is no genotoxic concern in humans for HI-6-dimethanesulfonate.

  15. HI-6 modulates immunization efficacy in a BALB/c mouse model.

    PubMed

    Pohanka, Miroslav

    2013-11-01

    HI-6 is used as an antidote to nerve agents. It can also act as an antagonist to acetylcholine receptors (AChRs) including the nicotinic receptor, α 7 nAChR which is involved in regulating the immune response through macrophages. This experiment investigated the efficacy of HI-6 to regulate the immune response. Laboratory BALB/c mice received HI-6 and/or keyhole limpet hemocyanin (KLH) as an antigen. Antibody production was investigated after either 21 or 65 days when either single or repeated dose of antigen was applied. We confirmed that HI-6 significantly improved vaccination efficacy when KLH was given in a dose of 1mg/kg. The effect was dose dependent. A combination of HI-6 and KLH produced a vaccination of almost the same efficacy as that for Freund's complete adjuvant. The findings point at the suitability of HI-6 for improving vaccination efficacy at the level of immunity regulation by the nervous system.

  16. Freeze-drying of HI-6-loaded recombinant human serum albumin nanoparticles for improved storage stability.

    PubMed

    Dadparvar, Miriam; Wagner, Sylvia; Wien, Sascha; Worek, Franz; von Briesen, Hagen; Kreuter, Jörg

    2014-10-01

    Severe intoxications with organophosphates require the immediate administration of atropine in combination with acetyl cholinesterase (AChE) reactivators such as HI-6. Although this therapy regimen enables the treatment of peripheral symptoms, the blood-brain barrier (BBB) restricts the access of the hydrophilic antidotes to the central nervous system which could lead to a fatal respiratory arrest. Therefore, HI-6-loaded albumin nanoparticles were previously developed to enhance the transport across this barrier and were able to reactivate organophosphate-(OP)-inhibited AChE in an in vitro BBB model. Since HI-6 is known to be moisture-sensitive, the feasibility of freeze-drying of the HI-6-loaded nanoparticles was investigated in the present study using different cryo- and lyoprotectants at different concentrations. Trehalose and sucrose (3%, w/v)-containing formulations were superior to mannitol concerning the physicochemical parameters of the nanoparticles whereas trehalose-containing samples were subject of a prolonged storage stability study at temperatures between -20°C and +40°C for predetermined time intervals. Shelf-life computations of the freeze-dried HI-6 nanoparticle formulations revealed a shelf-life time of 18 months when stored at -20°C. The formulations' efficacy was proven in vitro by reactivation of OP-inhibited AChE after transport over a porcine brain capillary endothelial cell layer model.

  17. Sulfur mustard induced oxidative stress and its alteration using asoxime (HI-6).

    PubMed

    Pohanka, Miroslav; Sobotka, Jakub; Svobodova, Hana; Stetina, Rudolf

    2013-12-01

    Sulfur mustard (SM) is a blister agent with cytotoxic mechanism of action. There is no suitable treatment based on administration of an antidote. In this study, Wistar rats were exposed to SM in doses of 0-40 mg/kg body weight and treated with the compound HI-6. The treatment provided no significant effect on ferric reducing antioxidant power of blood and plasma. However, HI-6 caused an increase in the level of thiobarbituric acid reactive substances. This stressogenic response was presumably the cause of the significant elevation of the blood level of both glutathione reductase and reduced glutathione. HI-6 appears to be suitable for enhancing prophylactically oxidative stress protection from small oxidative insult.

  18. Studies on the decomposition of the oxime HI 6 in aqueous solution.

    PubMed

    Eyer, P; Hell, W; Kawan, A; Klehr, H

    1986-12-01

    HI 6 has been shown to be efficacious in soman intoxication of laboratory animals by reactivation of acetylcholinesterase. To assess possible risks involved in the administration of HI 6 its degradation products were analyzed at pH 2.0, 4.0, 7.4, and 9.0. At pH 2.0, where HI 6 in aqueous solution has its maximal stability, attack on the aminal-acetal bond of the "ether bridge" predominates, with formation of formaldehyde, isonicotinamide, and pyridine-2-aldoxime. Besides, HI 6 decomposes at the oxime group yielding 2-cyanopyridine. Liberation of hydrocyanic acid at pH 2.0 is below 5%. At pH 7.4, primary attack is on the oxime group, resulting in formation of the corresponding pyridone via an intermediate nitrile. The pyridone has been isolated and identified as 2-pyridinone, 1-[(4-carbamoylpyridinio)methoxy)methyl)formate. This major metabolite deaminates further to the 2-pyridinone, 1-[(4-carboxypyridinio)methoxy)methyl) derivative, which ultimately decomposes into formaldehyde, isonicotinic acid, and 2-pyridone. Hydrolysis of the acid amide group probably also occurs with HI 6 itself. Significant amounts of free hydrocyanic acid were only detected in the presence of an alkali trap; otherwise hydrocyanic acid reacts with formaldehyde to yield hydroxyacetonitrile from which hydrocyanic acid can be liberated again. Up to 0.6 equivalents of hydrocyanic acid were evolved at pH 7.4. After repetitive administration and impaired renal elimination of HI 6, e.g. during renal shock, there might be some risk of cyanide intoxication. PMID:3827594

  19. In vivo distribution of organophosphate antidotes: autoradiography of (/sup 14/C)HI-6 in the rat

    SciTech Connect

    Ligtenstein, D.A.; Moes, G.W.; Kossen, S.P.

    1988-02-01

    In order to visualize the distribution of HI-6 in the rat after iv administration, autoradiographic experiments were carried out with (/sup 14/C)HI-6, labeled at the carbon of the carboxamide moiety. Autoradiography clearly confirms penetration of HI-6 into the central nervous system. Considerable radioactivity was found in the cerebrum, the cerebellum, and the choroid plexus. No significant activity was detected in the pontomedullary region or the spinal cord. Peripherally, (/sup 14/C)HI-6 is observed in large amounts in kidneys, heart, liver, nose, bladder, testes, and marrow-containing bone. The gastrointestinal tract was largely devoid of any radioactivity. The relative absence of HI-6 in the pontomedullary region renders centrally mediated influences of HI-6 on hemodynamic and respiratory parameters less likely.

  20. Characterization of soman toxicity in atropine and oxime (Hi-6 and MMB-4) treated rhesus monkeys

    SciTech Connect

    Olson, C.T.; Menton, R.G.; Kiser, R.C.; Hobson, D.W.

    1993-05-13

    There is a need for improved therapeutic compounds, specifically oximes, for humans exposed to organophosphorus (OP) anticholinesterase agents. Although pyridine-2-aldoxime (pralidoxime chloride; 2-PAM), the standard therapeutic oxime, is effective for treating exposure to certain OPs, it is only a marginally effective treatment for intoxications produced by other OPs such as pinacolylmethylphosphonofluoridate (soman; GD). Two bispyridinium oximes, HI-6 and MMB-4, have been suggested as replacements for 2-PAM in the treatment of OP intoxications in man. A study was conducted at Battelle's Medical Research and Evaluation Facility to determine the efficacies of HI-6 and MMB-4, given with atropine, in alleviating the signs of GD intoxication in monkeys. Treatments were administered 1 min after GD injection using a demonstrated efficacious dose of 0.4 mg atropine free base per kilogram of body weight, and 100 umol/kg of either candidate oxime. Although there is not a complete understanding of mechanism(s) of action, HI-6 proved more efficacious than MMB-4 in preventing lethality and in decreasing duration of clinical signs of GD intoxication.

  1. Development of a Combined Solution Formulation of Atropine Sulfate and Obidoxime Chloride for Autoinjector and Evaluation of Its Stability

    PubMed Central

    Ettehadi, Hossein Ali; Ghalandari, Rouhollah; Shafaati, Alireza; Foroutan, Seyed Mohsen

    2013-01-01

    Atropine (AT) and oximes, alone or in combination, have been proven greatly valuable therapeutics in the treatment of organophosphates intoxications. An injectable mixture of AT and obidoxime (OB) was formulated for the administration by automatic self-injector. The aqueous single dose solution contained 275 mg obidoxime chloride and 2.5 mg atropine sulfate per 1 mL (220 mg and 2 mg per 0.8 effective dose, respectively). The final solution was sterilized by filtration through a 0.22 μm pore size filter. This more concentrated solution allowed to use a smaller size and lighter weight cartridge. Quality control tests, including assay of the two major compounds were performed separately, using reversed-phase HPLC methods. Besides, the stability test was carried out according to ICH guideline for the accelerated test. The obtained results showed that the proposed formulation is stable over a period of 2 years after preparation. PMID:24250669

  2. Investigation of oxidative stress in blood, brain, kidney, and liver after oxime antidote HI-6 application in a mouse experimental model.

    PubMed

    Pohanka, Miroslav; Sobotka, Jakub; Svobodova, Hana; Stetina, Rudolf

    2011-07-01

    Oxime reactivator HI-6 (asoxime, in some sources) is a potent antidote suitable for treatment of intoxication by nerve agents. Despite the fact that HI-6 is considered for practical application in emergency situations, the impact of HI-6 on patients' bodies has not been established yet. The present experiment was carried out in order to estimate whether HI-6 would be able to trigger or protect from oxidative stress in a BALB/c mice model. HI-6 was applied in doses ranging from 0.2 to 20% of LD₅₀. Ferric-reducing antioxidant power (FRAP), thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH), and glutathione reductase (GR) were assayed in the blood, liver, kidney, and brain of treated animals. It was found that HI-6 does not increase GR or TBARS. On the contrary, TBARS levels in the brain and liver were found to be significantly decreased in HI-6-treated animals. Pertinent antioxidant properties of HI-6 were excluded by the FRAP method. Endogenous antioxidants were unchanged, with the exception of the kidney. Low-molecular-weight antioxidants assayed by the FRAP method were significantly decreased in kidneys of animals treated with HI-6. However, GSH partially recovered the loss of the other low-molecular-weight antioxidants and was significantly increased in the kidney of HI-6-exposed mice. HI-6 potential to produce nephropathy is hypothesized. The achieved conclusions were quite surprising and showed a complex impact of HI-6 on the body.

  3. Efficacy of antidotes (midazolam, atropine and HI-6) on nerve agent induced molecular and neuropathological changes

    PubMed Central

    2014-01-01

    Background Recent alleged attacks with nerve agent sarin on civilians in Syria indicate their potential threat to both civilian and military population. Acute nerve agent exposure can cause rapid death or leads to multiple and long term neurological effects. The biochemical changes that occur following nerve agent exposure needs to be elucidated to understand the mechanisms behind their long term neurological effects and to design better therapeutic drugs to block their multiple neurotoxic effects. In the present study, we intend to study the efficacy of antidotes comprising of HI-6 (1-[[[4-(aminocarbonyl)-pyridinio]-methoxy]-methyl]-2-[(hydroxyimino) methyl] pyridinium dichloride), atropine and midazolam on soman induced neurodegeneration and the expression of c-Fos, Calpain, and Bax levels in discrete rat brain areas. Results Therapeutic regime consisting of HI-6 (50 mg/kg, i.m), atropine (10 mg/kg, i.m) and midazolam (5 mg/kg, i.m) protected animals against soman (2 × LD50, s.c) lethality completely at 2 h and 80% at 24 h. HI-6 treatment reactivated soman inhibited plasma and RBC cholinesterase up to 40%. Fluoro-Jade B (FJ-B) staining of neurodegenerative neurons showed that soman induced significant necrotic neuronal cell death, which was reduced by this antidotal treatment. Soman increased the expression of neuronal proteins including c-Fos, Bax and Calpain levels in the hippocampus, cerebral cortex and cerebellum regions of the brain. This therapeutic regime also reduced the soman induced Bax, Calpain expression levels to near control levels in the different brain regions studied, except a mild induction of c-Fos expression in the hippocampus. Conclusion Rats that received antidotal treatment after soman exposure were protected from mortality and showed reduction in the soman induced expression of c-Fos, Bax and Calpain and necrosis. Results highlight the need for timely administration of better antidotes than standard therapy in order to prevent the

  4. Comparison of cholinergic effects of Hi-6 and pralidoxime-2-chloride (2-pam) in soman poisoning. (Reannouncement with new availability information). Open literature pub

    SciTech Connect

    Shi, T.M.; Whalley, C.E.; Valdes, J.J.

    1991-12-31

    The effects of HI-6 and pralidoxime chloride (2-PAM) on soman-induced lethality, time to death and several cholinergic parameters in rats were compared to understand the beneficial action of HI-6. Treatment with atropine sulfate (ATS) of HI-6 alone protected against 1.2 and 2.5 LD of soman respectively, whereas 2-Pam or methylated atropine (AMN) alone afforded no protection. Addition of ATS, but not AMN, to HI-6-treated rats enhanced the protection from 2.5 to 5.5 LD. HI-6 increased the time to death, while 2-PAM had no effect; a combination of HI-6 and ATS provided the most significant increase in time-to-death.

  5. Intranasal delivery of obidoxime to the brain prevents mortality and CNS damage from organophosphate poisoning.

    PubMed

    Krishnan, Jishnu K S; Arun, Peethambaran; Appu, Abhilash P; Vijayakumar, Nivetha; Figueiredo, Taíza H; Braga, Maria F M; Baskota, Sudikshya; Olsen, Cara H; Farkas, Natalia; Dagata, John; Frey, William H; Moffett, John R; Namboodiri, Aryan M A

    2016-03-01

    Intranasal delivery is an emerging method for bypassing the blood brain barrier (BBB) and targeting therapeutics to the CNS. Oximes are used to counteract the effects of organophosphate poisoning, but they do not readily cross the BBB. Therefore, they cannot effectively counteract the central neuropathologies caused by cholinergic over-activation when administered peripherally. For these reasons we examined intranasal administration of oximes in an animal model of severe organophosphate poisoning to determine their effectiveness in reducing mortality and seizure-induced neuronal degeneration. Using the paraoxon model of organophosphate poisoning, we administered the standard treatment (intramuscular pralidoxime plus atropine sulphate) to all animals and then compared the effectiveness of intranasal application of obidoxime (OBD) to saline in the control groups. Intranasally administered OBD was effective in partially reducing paraoxon-induced acetylcholinesterase inhibition in the brain and substantially reduced seizure severity and duration. Further, intranasal OBD completely prevented mortality, which was 41% in the animals given standard treatment plus intranasal saline. Fluoro-Jade-B staining revealed extensive neuronal degeneration in the surviving saline-treated animals 24h after paraoxon administration, whereas no detectable degenerating neurons were observed in any of the animals given intranasal OBD 30min before or 5min after paraoxon administration. These findings demonstrate that intranasally administered oximes bypass the BBB more effectively than those administered peripherally and provide an effective method for protecting the brain from organophosphates. The addition of intranasally administered oximes to the current treatment regimen for organophosphate poisoning would improve efficacy, reducing both brain damage and mortality. PMID:26751814

  6. Contribution of direct actions of the oxime HI-6 in reversing soman-induced muscle weakness in the rat diaphragm.

    PubMed

    Adler, M; Maxwell, D M; Filbert, M G; Deshpande, S S

    1994-01-01

    The actions of the bispyridinium oxime HI-6 ([[[(4-aminocarbonyl)pyridino]-methoxy]methyl]-2- [(hydroxyimino)methyl]-pyridinium dichloride) were investigated in vitro on rat phrenic nerve-hemidiaphragm preparations. Isometric twitch and tetanic tensions were elicited at 37 degrees C with supramaximal nerve stimulation at frequencies of 20 and 50 Hz. To approximate normal respiration patterns, trials consisting of 30 successive 0.55 s trains were alternated with 1.25 s rest periods. Under control conditions, the above stimulation pattern generated tensions that were well maintained at both frequencies. In contrast, a marked depression of muscle tension was observed in diaphragms removed from rats administered 339 micrograms/kg soman (3 LD50) and tested in vitro. Addition of HI-6, 4 h after soman exposure, led to a nearly complete recovery of muscle tension at 20 Hz. At 50 Hz, muscle tensions still declined especially when trains were elicited at 1.25 and 3 s intervals. The recovery by HI-6 observed in this study appears to be mediated by mechanisms unrelated to acetylcholinesterase reactivation since no increase of enzymatic activity was detected and the effect was reversed by a brief washout in oxime-free physiological solution. The results suggest that the direct action of HI-6 may play a role in restoring soman-induced diaphragmatic failure but this effect would be significant primarily under low use conditions. PMID:8157086

  7. Repetitive obidoxime treatment induced increase of red blood cell acetylcholinesterase activity even in a late phase of a severe methamidophos poisoning: A case report.

    PubMed

    Steinritz, Dirk; Eyer, Florian; Worek, Franz; Thiermann, Horst; John, Harald

    2016-02-26

    Accidental self-poisoning or deliberate use in suicidal intent of organophosphorus pesticides (OPP), which are widely used in agriculture, represent a health problem worldwide. Symptoms of poisoning are characterized by acute cholinergic crisis caused by inhibition of acetylcholinesterase. A 75-year-old male patient ingested 20ml of an OPP solution containing 10% methamidophos in suicidal intent. In the course of poisoning typical clinical symptoms of cholinergic crisis (miosis, bradycardia, hypotension, hypersalivation and impairment of neurologic status) were evident. Butyryl (plasma) cholinesterase (BChE) and red blood cell acetylcholinesterase (RBC-AChE) revealed decreased activities, thus specific treatment with the enzyme reactivator obidoxime was started. Inhibitory activity of the patient's plasma indicated significant amounts of persisting methamidophos in the circulation and was still found on day 4 after ingestion. Due to missing spontaneous breathing on day 6, obidoxime was administered again. Afterwards a significant increase of RBC-AChE activity was found. The patient was extubated on day 10 and a restitution ad integrum was achieved. In conclusion, obidoxime is a potent reactivator of OPP-inhibited AChE. A repetitive and prolonged administration of obidoxime should be considered in cases of severe methamidophos poisoning and should be tailored with an advanced analytical biomonitoring.

  8. Rapid-releasing of HI-6 via brain-targeted mesoporous silica nanoparticles for nerve agent detoxification

    NASA Astrophysics Data System (ADS)

    Yang, Jun; Fan, Lixue; Wang, Feijian; Luo, Yuan; Sui, Xin; Li, Wanhua; Zhang, Xiaohong; Wang, Yongan

    2016-05-01

    The toxic nerve agent (NA) soman is the most toxic artificially synthesized compound that can rapidly penetrate into the brain and irreversibly inhibit acetylcholinesterase (AChE) activity, leading to immediate death. However, there are currently few brain-targeted nanodrugs that can treat acute chemical brain poisoning owing to the limited drug-releasing speed. The present study investigated the effectiveness of a nanodrug against NA toxicity that has high blood-brain barrier penetration and is capable of rapid drug release. Transferrin-modified mesoporous silica nanoparticles (TF-MSNs) were conjugated with the known AChE reactivator HI-6. This nanodrug rapidly penetrated the blood-brain barrier in zebrafish and mice and restored cerebral AChE activity via the released HI-6, preventing the brain damage caused by soman poisoning and increasing the survival rate in mice. Furthermore, there was no toxicity associated with the MSNs in mice or rats. These results demonstrate that TF-MSNs loaded with HI-6 represent the most effective antidote against NA poisoning by soman reported to date, and suggest that MSNs are a safe alternative to conventional drugs and an optimal nanocarrier for treating brain poisoning, which requires acute pulse cerebral administration.The toxic nerve agent (NA) soman is the most toxic artificially synthesized compound that can rapidly penetrate into the brain and irreversibly inhibit acetylcholinesterase (AChE) activity, leading to immediate death. However, there are currently few brain-targeted nanodrugs that can treat acute chemical brain poisoning owing to the limited drug-releasing speed. The present study investigated the effectiveness of a nanodrug against NA toxicity that has high blood-brain barrier penetration and is capable of rapid drug release. Transferrin-modified mesoporous silica nanoparticles (TF-MSNs) were conjugated with the known AChE reactivator HI-6. This nanodrug rapidly penetrated the blood-brain barrier in zebrafish and

  9. Rapid-releasing of HI-6 via brain-targeted mesoporous silica nanoparticles for nerve agent detoxification.

    PubMed

    Yang, Jun; Fan, Lixue; Wang, Feijian; Luo, Yuan; Sui, Xin; Li, Wanhua; Zhang, Xiaohong; Wang, Yongan

    2016-05-01

    The toxic nerve agent (NA) soman is the most toxic artificially synthesized compound that can rapidly penetrate into the brain and irreversibly inhibit acetylcholinesterase (AChE) activity, leading to immediate death. However, there are currently few brain-targeted nanodrugs that can treat acute chemical brain poisoning owing to the limited drug-releasing speed. The present study investigated the effectiveness of a nanodrug against NA toxicity that has high blood-brain barrier penetration and is capable of rapid drug release. Transferrin-modified mesoporous silica nanoparticles (TF-MSNs) were conjugated with the known AChE reactivator HI-6. This nanodrug rapidly penetrated the blood-brain barrier in zebrafish and mice and restored cerebral AChE activity via the released HI-6, preventing the brain damage caused by soman poisoning and increasing the survival rate in mice. Furthermore, there was no toxicity associated with the MSNs in mice or rats. These results demonstrate that TF-MSNs loaded with HI-6 represent the most effective antidote against NA poisoning by soman reported to date, and suggest that MSNs are a safe alternative to conventional drugs and an optimal nanocarrier for treating brain poisoning, which requires acute pulse cerebral administration.

  10. Catalytic-site conformational equilibrium in nerve-agent adducts of acetylcholinesterase: possible implications for the HI-6 antidote substrate specificity.

    PubMed

    Artursson, Elisabet; Andersson, Per Ola; Akfur, Christine; Linusson, Anna; Börjegren, Susanne; Ekström, Fredrik

    2013-05-01

    Nerve agents such as tabun, cyclosarin and Russian VX inhibit the essential enzyme acetylcholinesterase (AChE) by organophosphorylating the catalytic serine residue. Nucleophiles, such as oximes, are used as antidotes as they can reactivate and restore the function of the inhibited enzyme. The oxime HI-6 shows a notably low activity on tabun adducts but can effectively reactivate adducts of cyclosarin and Russian VX. To examine the structural basis for the pronounced substrate specificity of HI-6, we determined the binary crystal structures of Mus musculus AChE (mAChE) conjugated by cyclosarin and Russian VX and found a conformational mobility of the side chains of Phe338 and His447. The interaction between HI-6 and tabun-adducts of AChE were subsequently investigated using a combination of time resolved fluorescence spectroscopy and X-ray crystallography. Our findings show that HI-6 binds to tabun inhibited Homo sapiens AChE (hAChE) with an IC50 value of 300μM and suggest that the reactive nucleophilic moiety of HI-6 is excluded from the phosphorus atom of tabun. We propose that a conformational mobility of the side-chains of Phe338 and His447 is a common feature in nerve-agent adducts of AChE. We also suggest that the conformational mobility allow HI-6 to reactivate conjugates of cyclosarin and Russian VX while a reduced mobility in tabun conjugated AChE results in steric hindrance that prevents efficient reactivation.

  11. Comparison of the efficacy of HI6 and 2-PAM against soman, tabun, sarin, and VX in the rabbit

    SciTech Connect

    Koplovitz, I.; Stewart, J.R.

    1994-12-31

    This study compared the efficacy of H16 and 2-PAM against nerve agent (soman tabun sarin and VX) -induced lethality in the atropinesterase-free rabbits pretreated with vehicle (controls) or pyridostigmine. Treatment was administered at signs or 2 min after agent challenge and consisted ofoxime (l00umol/lkg) + atropine 13 mg(kg) (alone or together with diazepam). Twenty-four-h LD50 values were calculated for soman- and tabun-intoxicated animals, whereas 24-h survival was noted in animals given 10 LD50s of sarin or VX. In pyridostigmine and control rabbits intoxicated with soman and treated with oxime + atropine (alone or together with diazepam), HI6 was 35 times more effective than 2-PAM. In contrast 1116 was less effective than 2-PAM against tabun poisoning. In pyridostigmine-pretreated animals exposed to tabun, efficacy was increased more than 3-fold when compare to tabun-challenged animals treated with atropine + H16 alone. Both oximes were highly effective against satin and VX. These findings suggest that Hifi could replace 2-PAM as therapy for nerve agent poisoning because it is superior to 2-PAM against soman, and when used in pyridostigmine-pretreated animals it affords excellent protection against all four nerve agents when used in combination with atropine (alone or together with diazepam) therapy.

  12. Subacute intramuscular toxicity of the acetylcholinesterase reactivating agent Hi-6 in rats and dogs. (Reannouncement with new availability information)

    SciTech Connect

    Levine, B.S.; Tomlinson, M.J.

    1993-12-31

    Studies herein describe the toxicity of HI-6 in Sprague-Dawley rats and Beagle dogs following i.m. injection for 14 days. Dose levels were 0, 50, 150, and 450 mg/kg/day for 10 rats/sex/dose and 0, 35, 70, and 140 mg/kg/day for 4 dogs/sex/dose. Three rats at the high dose, 2 males and 1 female, died prior to scheduled sacrifice. Reduced weight gain, decreased activity, tremors, hunched posture,and poor grooming were seen in high dose survivors. Increased alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities at the mid and high doses suggested hepatotoxicity, although liver weights and histology were normal. Hematology parameters were unaffected except for slight, dose-related increases of platelets in both sexes. Injection site inflammation was seen; however, serum creatine kinase activity was not altered. In dogs, slight weight loss, vomiting, salivation, and diarrhea occurred at the high dose, but no deaths were observed at any of the doses. As with rats, dose-related increases in ALT and AST activities occurred at the mid and high doses, and were, in this case, accompanied at the high dose by hepatomegaly and hepatocellular vacuolization. Cardiotoxicity was evidenced by increased relative heart weights and subtle ECG changes, the latter of which occurred almost exclusively at the highest dose. Injection site inflammation, which was accompanied by dose-related elevations in serum CK-MM2 activity, was also observed.

  13. Structure of a prereaction complex between the nerve agent sarin, its biological target acetylcholinesterase, and the antidote HI-6

    PubMed Central

    Allgardsson, Anders; Berg, Lotta; Akfur, Christine; Hörnberg, Andreas; Linusson, Anna; Ekström, Fredrik J.

    2016-01-01

    Organophosphorus nerve agents interfere with cholinergic signaling by covalently binding to the active site of the enzyme acetylcholinesterase (AChE). This inhibition causes an accumulation of the neurotransmitter acetylcholine, potentially leading to overstimulation of the nervous system and death. Current treatments include the use of antidotes that promote the release of functional AChE by an unknown reactivation mechanism. We have used diffusion trap cryocrystallography and density functional theory (DFT) calculations to determine and analyze prereaction conformers of the nerve agent antidote HI-6 in complex with Mus musculus AChE covalently inhibited by the nerve agent sarin. These analyses reveal previously unknown conformations of the system and suggest that the cleavage of the covalent enzyme–sarin bond is preceded by a conformational change in the sarin adduct itself. Together with data from the reactivation kinetics, this alternate conformation suggests a key interaction between Glu202 and the O-isopropyl moiety of sarin. Moreover, solvent kinetic isotope effect experiments using deuterium oxide reveal that the reactivation mechanism features an isotope-sensitive step. These findings provide insights into the reactivation mechanism and provide a starting point for the development of improved antidotes. The work also illustrates how DFT calculations can guide the interpretation, analysis, and validation of crystallographic data for challenging reactive systems with complex conformational dynamics. PMID:27140636

  14. Russian VX: inhibition and reactivation of acetylcholinesterase compared with VX agent.

    PubMed

    Kuca, Kamil; Jun, Daniel; Cabal, Jiri; Hrabinova, Martina; Bartosova, Lucie; Opletalova, Veronika

    2006-04-01

    Organophosphorus compounds such as nerve agents inhibit, practically irreversibly, cholinesterases by their phosphorylation in the active site of these enzymes. Current antidotal treatment used in the case of acute nerve agent intoxications consists of combined administration of anticholinergic drug (usually atropine) and acetylcholinesterase (AChE, EC 3.1.1.7) reactivator (HI-6, obidoxime, pralidoxime), which from a chemical view is a derivative from the group of pyridinium or bispyridinium aldoximes (commonly called "oxime"). Oximes counteract acetylcholine increase, resulting from AChE inhibition. In the human body environment these compounds are powerful nucleophiles and are able to break down the bond between AChE and nerve agent molecule. This process leads to renewal of enzyme functionality -- to its reactivation. The usefulness of oxime in the reactivation process depends on its chemical structure and on the nerve agent whereby AChE is inhibited. Due to this fact, selection of suitable reactivator in the treatment of intoxications is very important. In our work, we have compared differences in the in vitro inhibition potency of VX and Russian VX on rat, pig and human brain, and subsequently we have tested reactivation of rat brain cholinesterase inhibited by these agents using oxime HI-6, obidoxime, pralidoxime, trimedoxime and methoxime. The results showed that no major differences in the reactivation process of both VX and Russian VX-inhibited cholinesterase. The similarity in reactivation was caused by analogous chemical structure of either nerve agent; and that oxime HI-6 seems to be the most effective reactivator tested, which confirms that HI-6 is currently the most potent reactivator of AChE inhibited by nerve agents. The results obtained in our study should be considered in the future development of new AChE reactivators.

  15. Unequal Efficacy of Pyridinium Oximes in Acute Organophosphate Poisoning

    PubMed Central

    Antonijevic, Biljana; Stojiljkovic, Milos P.

    2007-01-01

    The use of organophosphorus pesticides results in toxicity risk to non-target organisms. Organophosphorus compounds share a common mode of action, exerting their toxic effects primarily via acetylcholinesterase (AChE) inhibition. Consequently, acetylcholine accumulates in the synaptic clefts of muscles and nerves, leading to overstimulation of cholinergic receptors. Acute cholinergic crisis immediately follows exposure to organophosphate and includes signs and symptoms resulting from hyperstimulation of central and peripheral muscarinic and nicotinic receptors. The current view of the treatment of organophosphate poisoning includes three strategies, i.e. the use of an anticholinergic drug (e.g., atropine), cholinesterase-reactivating agents (e.g., oximes) and anticonvulsant drugs (e.g., benzodiazepines). Oximes, as a part of antidotal therapy, ensure the recovery of phosphylated enzymes via a process denoted as reactivation of inhibited AChE. However, both experimental results and clinical findings have demonstrated that different oximes are not equally effective against poisonings caused by structurally different organophosphorus compounds. Therefore, antidotal characteristics of conventionally used oximes can be evaluated regarding how close the certain substance is to the theoretical concept of the universal oxime. Pralidoxime (PAM-2), trimedoxime (TMB-4), obidoxime (LüH-6), HI-6 and HLö-7 have all been demonstrated to be very effective in experimental poisonings with sarin and VX. TMB-4 and LüH-6 may reactivate tabun-inhibited AChE, whereas HI-6 possesses the ability to reactivate the soman-inhibited enzyme. An oxime HLö-7 seems to be an efficient reactivator of AChE inhibited by any of the four organophosphorus warfare agents. According to the available literature, the oximes LüH-6 and TMB-4, although relatively toxic, are the most potent to induce reactivation of AChE inhibited by the majority of organophosphorus pesticides. Since there are no reports of

  16. A structure-activity analysis of the variation in oxime efficacy against nerve agents

    SciTech Connect

    Maxwell, Donald M. Koplovitz, Irwin; Worek, Franz; Sweeney, Richard E.

    2008-09-01

    A structure-activity analysis was used to evaluate the variation in oxime efficacy of 2-PAM, obidoxime, HI-6 and ICD585 against nerve agents. In vivo oxime protection and in vitro oxime reactivation were used as indicators of oxime efficacy against VX, sarin, VR and cyclosarin. Analysis of in vivo oxime protection was conducted with oxime protective ratios (PR) from guinea pigs receiving oxime and atropine therapy after sc administration of nerve agent. Analysis of in vitro reactivation was conducted with second-order rate contants (k{sub r2}) for oxime reactivation of agent-inhibited acetylcholinesterase (AChE) from guinea pig erythrocytes. In vivo oxime PR and in vitro k{sub r2} decreased as the volume of the alkylmethylphosphonate moiety of nerve agents increased from VX to cyclosarin. This effect was greater with 2-PAM and obidoxime (> 14-fold decrease in PR) than with HI-6 and ICD585 (< 3.7-fold decrease in PR). The decrease in oxime PR and k{sub r2} as the volume of the agent moiety conjugated to AChE increased was consistent with a steric hindrance mechanism. Linear regression of log (PR-1) against log (k{sub r2} {center_dot} [oxime dose]) produced two offset parallel regression lines that delineated a significant difference between the coupling of oxime reactivation and oxime protection for HI-6 and ICD585 compared to 2-PAM and obidoxime. HI-6 and ICD585 appeared to be 6.8-fold more effective than 2-PAM and obidoxime at coupling oxime reactivation to oxime protection, which suggested that the isonicotinamide group that is common to both of these oximes, but absent from 2-PAM and obidoxime, is important for oxime efficacy.

  17. Clinical observation and comparison of the effectiveness of several oxime cholinesterase reactivators.

    PubMed

    Xue, S Z; Ding, X J; Ding, Y

    1985-01-01

    After passing toxicity and experimental therapeutic tests, four oxime cholinesterase reactivators [PAM (pyridine aldoxime methiodide), PAC (pralidoxime, pyridine aldoxime methylchloride), TMB4 (trimedoxime), and DMO4 (obidoxime, Toxogonin, LüH6)] were compared in clinical trials. All of them proved capable of restoring erythrocyte cholinesterase activity and relieving symptoms and signs of organophosphate insecticide poisoning. Mildly and moderately poisoned patients can be treated by several injections of any one of these drugs alone, but severe cases need the synergistic action of atropine, as well as treatments for two to three consecutive days. Although response to treatment is stronger with TMB4 and DMO4, they are not recommended for routine treatment because of their dangerous adverse side effects.

  18. Clinical observation and comparison of the effectiveness of several oxime cholinesterase reactivators.

    PubMed

    Xue, S Z; Ding, X J; Ding, Y

    1985-01-01

    After passing toxicity and experimental therapeutic tests, four oxime cholinesterase reactivators [PAM (pyridine aldoxime methiodide), PAC (pralidoxime, pyridine aldoxime methylchloride), TMB4 (trimedoxime), and DMO4 (obidoxime, Toxogonin, LüH6)] were compared in clinical trials. All of them proved capable of restoring erythrocyte cholinesterase activity and relieving symptoms and signs of organophosphate insecticide poisoning. Mildly and moderately poisoned patients can be treated by several injections of any one of these drugs alone, but severe cases need the synergistic action of atropine, as well as treatments for two to three consecutive days. Although response to treatment is stronger with TMB4 and DMO4, they are not recommended for routine treatment because of their dangerous adverse side effects. PMID:3914075

  19. Comparison of acetylcholinesterase, pyridostigmine, and HI-6 as antidotes against organophosphorus compounds

    SciTech Connect

    Maxwell, D.M.; Brecht, K.M.; Saxena, A.; Taylor, P.; Doctor, B.P.

    1995-12-31

    Conventional medical treatment against the toxicity of organophosphorus (OP) compounds consists of a regimen of anticholinergic drugs to counteract the accumulation of acetylcholine and oximes to reactivate OP-inhibited acetylcholinesterase (AChE) (Taylor, 1985). Reactivation ofOP-inhibited AChE by oximes can generate enough active AChE in the peripheral nervous system, especially in the diaphragm, to restore normal cholinergic neurotransmission after exposure to many OP compounds. However, some OP compounds, such as soman (pinacolylmdhylphos phonofluofldate), inhibit AChE and rapidly age into a form that cannot be reactivated by oximes (De Jong and Wolring, 1984), thereby reducing the ability of oximes to provide protection (Maxwell and Brecht, 1991). The inability of oximes to provide adequate protection against the toxicity of rapidly aging OP compounds stimulated the development of carbamate pretreatment in which carbamylation of AChE effectively protects it against inhibition by OP compounds (Leadbeater et al., 1985). Spontaneous decarbamylation of AChE after the OP compound has been detoxified then generates enough active AChE to allow normal cholinergic neurotransmission. Behavioral side effects from carbamate pretreatment in the absence of exposure to OP compounds have been avoided by the use of cationic pretreatment carbamates, such as pyridostigmine, which do not enter the central nervous system.

  20. Development and Structural Modifications of Cholinesterase Reactivators against Chemical Warfare Agents in Last Decade: A Review.

    PubMed

    Sharma, Rahul; Gupta, Bhanushree; Singh, Namrata; Acharya, J R; Musilek, Kamil; Kuca, Kamil; Ghosh, Kallol Kumar

    2015-01-01

    Organophosphate (OP) pesticides and nerve agents are responsible for suicidal and accidental poisonings. The acute toxicity of nerve agents leads to progressive inhibition of the enzyme acetylcholinesterase (AChE) by phosphylation of serine residue at the active site of gorge. The recent massive destruction of Syrian civilians by nerve gas sarin, has again renewed the research attention of global science fraternity towards nerve agents, their mode of action and most prominently their therapeutic treatment. This review is principally focused on nerve agent intoxication. The common approach to deal with OP-intoxication is, application of antimuscarinic drug (atropine), anticonvulsant drug (diazepam) and clinically used oximes (pralidoxime, trimedoxime, obidoxime and asoxime). However, the existing therapeutic approach is arguable and has several failings to cure all kinds of nerve agent poisonings. Considering this issue, numerous oximes have been synthesized and screened through various in-vitro and in-vivo studies in last decade to overcome the downsides. At present, only a few oximes (bis pyridinum-oximes) exhibit sound efficacy against selective OPs. In spite of extensive efforts, till date no oxime is available as a universal antidote against all the classes of OPs. This review is centered on the recent developments and structural modification of AChE reactivators against nerve agent toxicity. In particular, a deeper look has been taken into chemical modifications of the reactivators by incorporation of different structural moieties targeted towards the increased reactivation affinity and improved blood brain barrier (BBB) penetration.

  1. A Comprehensive Evaluation of the Efficacy of Leading Oxime Therapies in Guinea Pigs Exposed to Organophosphorus Chemical Warfare Agents or Pesticides

    PubMed Central

    Wilhelm, Christina M.; Snider, Thomas H.; Babin, Michael C.; Jett, David A.; Platoff, Gennady E.; Yeung, David T.

    2014-01-01

    The currently fielded pre-hospital therapeutic regimen for the treatment of organophosphorus (OP) poisoning in the United States (U.S.) is the administration of atropine in combination with an oxime antidote (2-PAM Cl) to reactivate inhibited acetylcholinesterase (AChE). Depending on clinical symptoms, an anticonvulsant, e.g., diazepam, may also be administered. Unfortunately, 2-PAM Cl does not offer sufficient protection across the range of OP threat agents, and there is some question as to whether it is the most effective oxime compound available. The objective of the present study is to identify an oxime antidote, under standardized and comparable conditions, that offers protection at the FDA approved human equivalent dose (HED) of 2-PAM Cl against tabun (GA), sarin (GB), soman (GD), cyclosarin (GF), and VX, and the pesticides paraoxon, chlorpyrifos oxon, and phorate oxon. Male Hartley guinea pigs were subcutaneously challenged with a lethal level of OP and treated at approximately 1 min post challenge with atropine followed by equimolar oxime therapy (2-PAM Cl, HI-6 DMS, obidoxime Cl2, TMB-4, MMB4-DMS, HLö-7 DMS, MINA, and RS194B) or therapeutic-index (TI) level therapy (HI-6 DMS, MMB4-DMS, MINA, and RS194B). Clinical signs of toxicity were observed for 24 hours post challenge and blood cholinesterase [AChE and butyrylcholinesterase (BChE)] activity was analyzed utilizing a modified Ellman’s method. When the oxime is standardized against the HED of 2-PAM Cl for guinea pigs, the evidence from clinical observations, lethality, quality of life (QOL) scores, and cholinesterase reactivation rates across all OPs indicated that MMB4 DMS and HLö-7 DMS were the two most consistently efficacious oximes. PMID:25448441

  2. A comprehensive evaluation of the efficacy of leading oxime therapies in guinea pigs exposed to organophosphorus chemical warfare agents or pesticides.

    PubMed

    Wilhelm, Christina M; Snider, Thomas H; Babin, Michael C; Jett, David A; Platoff, Gennady E; Yeung, David T

    2014-12-15

    The currently fielded pre-hospital therapeutic regimen for the treatment of organophosphorus (OP) poisoning in the United States (U.S.) is the administration of atropine in combination with an oxime antidote (2-PAM Cl) to reactivate inhibited acetylcholinesterase (AChE). Depending on clinical symptoms, an anticonvulsant, e.g., diazepam, may also be administered. Unfortunately, 2-PAM Cl does not offer sufficient protection across the range of OP threat agents, and there is some question as to whether it is the most effective oxime compound available. The objective of the present study is to identify an oxime antidote, under standardized and comparable conditions, that offers protection at the FDA approved human equivalent dose (HED) of 2-PAM Cl against tabun (GA), sarin (GB), soman (GD), cyclosarin (GF), and VX, and the pesticides paraoxon, chlorpyrifos oxon, and phorate oxon. Male Hartley guinea pigs were subcutaneously challenged with a lethal level of OP and treated at approximately 1 min post challenge with atropine followed by equimolar oxime therapy (2-PAM Cl, HI-6 DMS, obidoxime Cl₂, TMB-4, MMB4-DMS, HLö-7 DMS, MINA, and RS194B) or therapeutic-index (TI) level therapy (HI-6 DMS, MMB4-DMS, MINA, and RS194B). Clinical signs of toxicity were observed for 24 h post challenge and blood cholinesterase [AChE and butyrylcholinesterase (BChE)] activity was analyzed utilizing a modified Ellman's method. When the oxime is standardized against the HED of 2-PAM Cl for guinea pigs, the evidence from clinical observations, lethality, quality of life (QOL) scores, and cholinesterase reactivation rates across all OPs indicated that MMB4 DMS and HLö-7 DMS were the two most consistently efficacious oximes.

  3. Assessment of acetylcholinesterase activity using indoxylacetate and comparison with the standard Ellman's method.

    PubMed

    Pohanka, Miroslav; Hrabinova, Martina; Kuca, Kamil; Simonato, Jean-Pierre

    2011-01-01

    Assay of acetylcholinesterase (AChE) activity plays an important role in diagnostic, detection of pesticides and nerve agents, in vitro characterization of toxins and drugs including potential treatments for Alzheimer's disease. These experiments were done in order to determine whether indoxylacetate could be an adequate chromogenic reactant for AChE assay evaluation. Moreover, the results were compared to the standard Ellman's method. We calculated Michaelis constant Km (2.06 × 10(-4) mol/L for acetylthiocholine and 3.21 × 10(-3) mol/L for indoxylacetate) maximum reaction velocity V(max) (4.97 × 10(-7) kat for acetylcholine and 7.71 × 10(-8) kat for indoxylacetate) for electric eel AChE. In a second part, inhibition values were plotted for paraoxon, and reactivation efficacy was measured for some standard oxime reactivators: obidoxime, pralidoxime (2-PAM) and HI-6. Though indoxylacetate is split with lower turnover rate, this compound appears as a very attractive reactant since it does not show any chemical reactivity with oxime antidots and thiol used for the Ellman's method. Thus it can be advantageously used for accurate measurement of AChE activity. Suitability of assay for butyrylcholinesterase activity assessment is also discussed.

  4. Reactivation of organophosphate-inhibited human, Cynomolgus monkey, swine and guinea pig acetylcholinesterase by MMB-4: A modified kinetic approach

    SciTech Connect

    Worek, Franz; Wille, Timo; Aurbek, Nadine; Eyer, Peter; Thiermann, Horst

    2010-12-15

    Treatment of poisoning by highly toxic organophosphorus compounds (OP, nerve agents) is a continuous challenge. Standard treatment with atropine and a clinically used oxime, obidoxime or pralidoxime is inadequate against various nerve agents. For ethical reasons testing of oxime efficacy has to be performed in animals. Now, it was tempting to investigate the reactivation kinetics of MMB-4, a candidate oxime to replace pralidoxime, with nerve agent-inhibited acetylcholinesterase (AChE) from human and animal origin in order to provide a kinetic basis for the proper assessment of in vivo data. By applying a modified kinetic approach, allowing the use of necessary high MMB-4 concentrations, it was possible to determine the reactivation constants with sarin-, cyclosarin-, VX-, VR- and tabun-inhibited AChE. MMB-4 exhibited a high reactivity and low affinity towards OP-inhibited AChE, except of tabun-inhibited enzyme where MMB-4 had an extremely low reactivity. Species differences between human and animal AChE were low (Cynomolgus) to moderate (swine, guinea pig). Due to the high reactivity of MMB-4 a rapid reactivation of inhibited AChE can be anticipated at adequate oxime concentrations which are substantially higher compared to HI-6. Additional studies are necessary to determine the in vivo toxicity, tolerability and pharmacokinetics of MMB-4 in humans in order to enable a proper assessment of the value of this oxime as an antidote against nerve agent poisoning.

  5. Kinetics and stability of a multicomponent organophosphate antidote formulation in glass and plastic

    SciTech Connect

    Zvirblis, P.; Ellin, R.I.

    1982-03-01

    An aqueous solution of trimedoxime bromide, atropine, and benactyzine hydrochloride was formulated to have maximum stability as an antidote in organophosphorus poisoning. The stability of the mixture in glass and plastic cartridges was determined. Glass cartridges were more desirable than plastic; there was less vapor loss, color formation, and anomalous reaction. Trimedoxime was stable, losing 1.4% of its potency after 1 year at 25 degrees and atropine was more stable than trimedoxime. Considerable degradation of benactyzine occurred; 20% of its potency was lost after 1 year at 25 degrees. Equations for predicting the shelf life of each ingredient at selected temperatures are presented.

  6. Limitations and challenges in treatment of acute chemical warfare agent poisoning.

    PubMed

    Thiermann, Horst; Worek, Franz; Kehe, Kai

    2013-12-01

    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

  7. Limitations and challenges in treatment of acute chemical warfare agent poisoning.

    PubMed

    Thiermann, Horst; Worek, Franz; Kehe, Kai

    2013-12-01

    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

  8. A comprehensive evaluation of the efficacy of leading oxime therapies in guinea pigs exposed to organophosphorus chemical warfare agents or pesticides

    SciTech Connect

    Wilhelm, Christina M.; Snider, Thomas H.; Babin, Michael C.; Jett, David A.

    2014-12-15

    The currently fielded pre-hospital therapeutic regimen for the treatment of organophosphorus (OP) poisoning in the United States (U.S.) is the administration of atropine in combination with an oxime antidote (2-PAM Cl) to reactivate inhibited acetylcholinesterase (AChE). Depending on clinical symptoms, an anticonvulsant, e.g., diazepam, may also be administered. Unfortunately, 2-PAM Cl does not offer sufficient protection across the range of OP threat agents, and there is some question as to whether it is the most effective oxime compound available. The objective of the present study is to identify an oxime antidote, under standardized and comparable conditions, that offers protection at the FDA approved human equivalent dose (HED) of 2-PAM Cl against tabun (GA), sarin (GB), soman (GD), cyclosarin (GF), and VX, and the pesticides paraoxon, chlorpyrifos oxon, and phorate oxon. Male Hartley guinea pigs were subcutaneously challenged with a lethal level of OP and treated at approximately 1 min post challenge with atropine followed by equimolar oxime therapy (2-PAM Cl, HI-6 DMS, obidoxime Cl{sub 2}, TMB-4, MMB4-DMS, HLö-7 DMS, MINA, and RS194B) or therapeutic-index (TI) level therapy (HI-6 DMS, MMB4-DMS, MINA, and RS194B). Clinical signs of toxicity were observed for 24 h post challenge and blood cholinesterase [AChE and butyrylcholinesterase (BChE)] activity was analyzed utilizing a modified Ellman's method. When the oxime is standardized against the HED of 2-PAM Cl for guinea pigs, the evidence from clinical observations, lethality, quality of life (QOL) scores, and cholinesterase reactivation rates across all OPs indicated that MMB4 DMS and HLö-7 DMS were the two most consistently efficacious oximes. - Highlights: • First comprehensive evaluation of leading AChE oxime reactivators • All oximes are compared against current U.S. therapy 2-PAM Cl. • Relative therapeutic oxime efficacies against OP CWNA and pesticides • Contribution to more effective antidotes

  9. Can hydroxylamine be a more potent nucleophile for the reactivation of tabun-inhibited AChE than prototype oxime drugs? An answer derived from quantum chemical and steered molecular dynamics studies.

    PubMed

    Lo, Rabindranath; Ganguly, Bishwajit

    2014-07-29

    Organophosphorus nerve agents are highly toxic compounds which strongly inhibit acetylcholinesterase (AChE) in the blood and in the central nervous system (CNS). Tabun is one of the highly toxic organophosphorus (OP) compounds and is resistant to many oxime drugs formulated for the reactivation of AChE. The reactivation mechanism of tabun-conjugated AChE with various drugs has been examined with density functional theory and ab initio quantum chemical calculations. The presence of a lone-pair located on the amidic group resists the nucleophilic attack at the phosphorus center of the tabun-conjugated AChE. We have shown that the newly designed drug candidate N-(pyridin-2-yl)hydroxylamine, at the MP2/6-31+G*//M05-2X/6-31G* level in the aqueous phase with the polarizable continuum solvation model (PCM), is more effective in reactivating the tabun-conjugated AChE than typical oxime drugs. The rate determining activation barrier with N-(pyridin-2-yl)hydroxylamine was found to be ∼1.7 kcal mol(-1), which is 7.2 kcal mol(-1) lower than the charged oxime trimedoxime (one of the most efficient reactivators in tabun poisonings). The greater nucleophilicity index (ω(-)) and higher CHelpG charge of pyridinylhydroxylamine compared to TMB4 support this observation. Furthermore, we have also examined the reactivation process of tabun-inhibited AChE with some other bis-quaternary oxime drug candidates such as methoxime (MMB4) and obidoxime. The docking analysis suggests that charged bis-quaternary pyridinium oximes have greater binding affinity inside the active-site gorge of AChE compared to the neutral pyridinylhydroxylamine. The peripheral ligand attached to the neutral pyridinylhydroxylamine enhanced the binding with the aromatic residues in the active-site gorge of AChE through effective π-π interactions. Steered molecular dynamics (SMD) simulations have also been performed with the charged oxime (TMB4) and the neutral hydroxylamine. From protein-drug interaction

  10. Daphnia intoxicated by nerve agent tabun can be treated using human antidotes.

    PubMed

    Vesela, Sarka; Kuca, Kamil; Jun, Daniel

    2008-05-01

    Application of human antidotes against nerve agent intoxications to microcrustacean Daphnia magna (Crustacea, Cladocera) intoxicated by a nerve agent tabun (O-ethyl-N,N-dimethylphosphoramidocyanidate) and their efficacy was investigated. It was found that antidotes can be successfully applied to intoxicated daphnids. Three different treatment regimens were tested: the combination of atropine and acetylcholinesterase reactivator (trimedoxime was chosen), atropine only and trimedoxime alone, too. The most efficient was the combination of atropine and trimedoxime followed by treatment with atropine only. The proportion of recovered animals increased with time not only in treated groups but also in the control as well. This can be explained by a spontaneous reactivation of tabun-inhibited cholinesterase in daphnids probably indicating a difference between mammalian and crustacean cholinesterases.

  11. Investigation of kinetic interactions between approved oximes and human acetylcholinesterase inhibited by pesticide carbamates.

    PubMed

    Wille, Timo; Kaltenbach, Lisa; Thiermann, Horst; Worek, Franz

    2013-12-01

    Carbamates are widely used for pest control and act primarily by inhibition of insect and mammalian acetylcholinesterase (AChE). Accidental or intentional uptake of carbamates may result in typical signs and symptoms of cholinergic overstimulation which cannot be discriminated from those of organophosphorus pesticide poisoning. There is an ongoing debate whether standard treatment with atropine and oximes should be recommended for human carbamate poisoning as well, since in vitro and in vivo animal data indicate a deleterious effect of oximes when used in combination with the N-methyl carbamate carbaryl. Therefore, we performed an in vitro kinetic study to investigate the effect of clinically used oximes on carbamoylation and decarbamoylation of human AChE. It became evident that pralidoxime and obidoxime in therapeutic concentrations aggravate the inhibition of AChE by carbaryl and propoxur, with obidoxime being substantially more potent compared to 2-PAM. However, obidoxime had no impact on the decarbamoylation kinetics. Hence, the administration of 2-PAM and especially of obidoxime to severely propoxur and carbaryl poisoned humans cannot be recommended.

  12. Efficacy of oxime plus atropine treatment against Soman poisoning in the atropinesterase-free rabbit. (Reannouncement with new availability information)

    SciTech Connect

    Koplovitz, I.; Stewart, J.R.

    1992-12-31

    The oximes pralidoxime chloride (2-PAM), MMB4, and HI-6 were evaluated in combination with atropine as treatments against soman poisoning in atropinesterase-free rabbits. Animals were challenged i.m. with 2 x LD50 soman and treated at the onset of toxic signs with 50 micron mol/kg of oxime and 5 or 13 mg/kg atropine. Survival and time to death were compared at 48 hours post-soman challenge. Survival rates in MMB4 and HI-6 treated animals were higher than in 2-PAM-treated animals. The increase in survival was significant at the 13 mg/kg dose of atropine. MMB4 and HI-6 also significantly delayed time to death after soman compared to 2-PAM. The results suggest that MMB4 and HI-6 have potential as useful oximes for treating soman poisoning.... Soman, Nerve agent, Treatment, Rabbit, HI-6, 2-PAM, Oxime therapy.

  13. Toxicity and median effective doses of oxime therapies against percutaneous organophosphorus pesticide and nerve agent challenges in the Hartley guinea pig.

    PubMed

    Snider, Thomas H; Babin, Michael C; Jett, David A; Platoff, Gennady E; Yeung, David T

    2016-01-01

    Anticholinesterases, such as organophosphorus pesticides and warfare nerve agents, present a significant health threat. Onset of symptoms after exposure can be rapid, requiring quick-acting, efficacious therapy to mitigate the effects. The goal of the current study was to identify the safest antidote with the highest therapeutic index (TI = oxime 24-hr LD50/oxime ED50) from a panel of four oximes deemed most efficacious in a previous study. The oximes tested were pralidoxime chloride (2-PAM Cl), MMB4 DMS, HLö-7 DMS, and obidoxime Cl2. The 24-hr median lethal dose (LD50) for the four by intramuscular (IM) injection and the median effective dose (ED50) were determined. In the ED50 study, male guinea pigs clipped of hair received 2x LD50 topical challenges of undiluted Russian VX (VR), VX, or phorate oxon (PHO) and, at the onset of cholinergic signs, IM therapy of atropine (0.4 mg/kg) and varying levels of oxime. Survival was assessed at 3 hr after onset clinical signs. The 3-hr 90th percentile dose (ED90) for each oxime was compared to the guinea pig pre-hospital human-equivalent dose of 2-PAM Cl, 149 µmol/kg. The TI was calculated for each OP/oxime combination. Against VR, MMB4 DMS had a higher TI than HLö-7 DMS, whereas 2-PAM Cl and obidoxime Cl2 were ineffective. Against VX, MMB4 DMS > HLö-7 DMS > 2-PAM Cl > obidoxime Cl2. Against PHO, all performed better than 2-PAM Cl. MMB4 DMS was the most effective oxime as it was the only oxime with ED90 < 149 µmol/kg against all three topical OPs tested. PMID:27432237

  14. Synthesis and in vitro reactivation study of isonicotinamide derivatives of 2-(hydroxyimino)-N-(pyridin-3-yl)acetamide as reactivators of Sarin and VX inhibited human acetylcholinesterase (hAChE).

    PubMed

    Karade, Hitendra N; Raviraju, G; Acharya, B N; Valiveti, Aditya Kapil; Bhalerao, Uma; Acharya, Jyotiranjan

    2016-09-15

    Previously (Karade et al., 2014), we have reported the synthesis and in vitro evaluation of bis-pyridinium derivatives of pyridine-3-yl-(2-hydroxyimino acetamide), as reactivators of sarin and VX inhibited hAChE. Few of the molecules showed superior in vivo protection efficacy (mice model) (Kumar et al., 2014; Swami et al., 2016) in comparison to 2-PAM against DFP and sarin poisoning. Encouraged by these results, herein we report the synthesis and in vitro evaluation of isonicotinamide derivatives of pyridine-3-yl-(2-hydroxyimino acetamide) (4a-4d) against sarin and VX inhibited erythrocyte ghost hAChE. Reactivation kinetics of these compounds was studied and the determined kinetic parameters were compared with that of commercial reactivators viz. 2-PAM and obidoxime. In comparison to 2-PAM and obidoxime, oxime 4a and 4b exhibited enhanced reactivation efficacy toward sarin inhibited hAChE while oxime 4c showed far greater reactivation efficacy toward VX inhibited hAChE. The acid dissociation constant and IC50 values of these oximes were determined and correlated with the observed reactivation potential. PMID:27450532

  15. Assessing the therapeutic efficacy of oxime therapies against percutaneous organophosphorus pesticide and nerve agent challenges in the Hartley guinea pig

    PubMed Central

    Snider, Thomas H.; Wilhelm, Christina M.; Babin, Michael C.; Platoff, Gennady E.; Yeung, David T.

    2016-01-01

    Given the rapid onset of symptoms from intoxication by organophosphate (OP) compounds, a quick-acting, efficacious therapeutic regimen is needed. A primary component of anti-OP therapy is an oxime reactivator to rescue OP-inhibited acetylcholinesterases. Male guinea pigs, clipped of hair, received neat applications of either VR, VX, parathion, or phorate oxon (PHO) at the 85th percentile lethal dose, and, beginning with presentation of toxicosis, received the human equivalent dose therapy by intramuscular injection with two additional follow-on treatments at 3-hr intervals. Each therapy consisted of atropine free base at 0.4 mg/kg followed by one of eight candidate oximes. Lethality rates were obtained at 24 hr after VR, VX and PHO challenges, and at 48 hr after challenge with parathion. Lethality rates among symptomatic, oxime-treated groups were compared with that of positive control (OP-challenged and atropine-only treated) guinea pigs composited across the test days. Significant (p ≤ 0.05) protective therapy was afforded by 1,1-methylene bis(4(hydroxyimino- methyl)pyridinium) dimethanesulfonate (MMB4 DMS) against challenges of VR (p ≤ 0.001) and VX (p ≤ 0.05). Lethal effects of VX were also significantly (p ≤ 0.05) mitigated by treatments with oxo-[[1-[[4-(oxoazaniumylmethylidene)pyridin-1-yl] methoxymethyl]pyridin-4-ylidene]methyl]azanium dichloride (obidoxime Cl2) and 1-(((4-(aminocarbonyl) pyridinio)methoxy)methyl)-2,4-bis((hydroxyimino)methyl)pyridinium dimethanesulfonate (HLö-7 DMS). Against parathion, significant protective therapy was afforded by obidoxime dichloride (p ≤ 0.001) and 1,1′-propane-1,3-diylbis{4-[(E)-(hydroxyimino)methyl]pyridinium} dibromide (TMB-4, p ≤ 0.01). None of the oximes evaluated was therapeutically effective against PHO. Across the spectrum of OP chemicals tested, the oximes that offered the highest level of therapy were MMB4 DMS and obidoxime dichloride. PMID:26558457

  16. Antidotal efficacy of bisquaternary oximes against soman and tabun poisoning in various species

    SciTech Connect

    Amitai, G.; Rabinovitz, I.; Chen, R.; Cohen, G.; Zomber, G.

    1993-05-13

    The introduction of Hagedorn oximes, e.g. HI-6 and HLo-7, was an important milestone in the development of antidotal treatment against soman poisoning. We have developed a series of 'cholinergic receptor-directed' AB-oximes which combine in their molecular structure both AChE reactivation potency and anti-cholinergic properties. Marked antidotal efficacy against soman and tabun poisoning was obtained for AB-8, AB-13, toxogonin, HLo-7 and HI-6 in conjunction with atropine and benactyzine in pyridostigmine (PYR) pretreated mice and guinea pigs. In the absence of PYR, all oximes except for HI-6 in mice or HI-6 and HLo-7 in guinea pigs provided poor protection (PR=1-2) against soman. In tabun poisoning, AB-13, toxogonin and HLO-7 conferred high PR values: 8.6, 21.3 and 21.7, respectively, even without PYR pretreatment. These data are consistent with reactivation potency of these oximes (kr = 12.5, 157 and 18.7 m(1) min(1), respectively) for tabun-inhibited FBS-AChE. Elimination of benactyzine significantly decreased the PR values obtained against soman in guinea pigs.

  17. 76 FR 12341 - Western Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-07

    .... SUPPLEMENTARY INFORMATION: The STAC will review the Council's 2010 sea turtle conservation projects and other... Management Council (Council) will hold a meeting of its Sea Turtle Advisory Committee (STAC) in Honolulu, HI... 6th STAC Meeting. 4. Overview of 2010-11 Council Sea Turtle Program. 5. Update of Sea...

  18. Catalytic soman scavenging by Y337A/F338A acetylcholinesterase mutant assisted with novel site-directed aldoximes

    PubMed Central

    Kovarik, Zrinka; Hrvat, Nikolina Maček; Katalinić, Maja; Sit, Rakesh K.; Paradyse, Alexander; Žunec, Suzana; Musilek, Kamil; Fokin, Valery V.; Taylor, Palmer; Radić, Zoran

    2016-01-01

    Exposure to the nerve agent soman is difficult to treat due to the rapid dealkylation of soman-acetylcholinesterase (AChE) conjugate known as aging. Oxime antidotes commonly used to reactivate organophosphate inhibited AChE are ineffective against soman, while the efficacy of the recommended nerve agent bioscavenger butyrylcholinesterase is limited by strictly stoichiometric scavenging. To overcome this limitation, we tested ex vivo, in human blood, and in vivo, in soman exposed mice, the capacity of aging-resistant human AChE mutant Y337A/F338A in combination with oxime HI-6 to act as a catalytic bioscavenger of soman. HI-6 was previously shown in vitro to efficiently reactivate this mutant upon soman, as well as VX, cyclosarin, sarin and paraoxon inhibition. We here demonstrate that ex vivo, in whole human blood, 1 μM soman was detoxified within 30 minutes when supplemented with 0.5 μM Y337A/F338A AChE and 100 μM HI-6. This combination was further tested in vivo. Catalytic scavenging of soman in mice improved the therapeutic outcome and resulted in the delayed onset of toxicity symptoms. Furthermore, in a preliminary in vitro screen we identified an even more efficacious oxime than HI-6, in a series of forty-two pyridinium aldoximes, and five imidazole 2-aldoxime N-propyl pyridinium derivatives. One of the later imidazole aldoximes, RS-170B, was a 2–3 –fold more effective reactivator of Y337A/F338A AChE than HI-6 due to the smaller imidazole ring, as indicated by computational molecular models, that affords a more productive angle of nucleophilic attack. PMID:25835984

  19. [Nerve gas--guidelines for care of victims of terrorism].

    PubMed

    Aas, Pål; Jacobsen, Dag

    2005-03-17

    The threat from chemical warfare agents such as nerve agents against civilians has traditionally been considered irrelevant. Following the recent terrorist attacks in the US on 11 September 2001 and in Madrid, Spain on 11 March 2004, the threat from such weapons is taken seriously. Hospitals must therefore be prepared to take care of civilian victims. Emergency preparedness implies education and training of healthcare professionals, stocking of antidotes, and training of personnel. This involves decontamination of patients, establishment of routines to avoid contamination of hospitals, and the ability to determine if patients and first responders are contaminated with chemicals and to avoid such contamination. Treatment against nerve agents includes atropine, acetylcholinesterase reactivators (obidoxime or pralidoxime) and benzodiazepines (diazepam). Because these drugs are not sufficiently effective in protecting the brain, new and more effective countermeasures must be developed.

  20. Actions and interactions of cholinolytics and cholinesterase reactivators in the treatment of acute organophosphorus toxicity.

    PubMed

    Das Gupta, S; Ghosh, A K; Chowdhri, B L; Asthana, S N; Batra, B S

    1991-01-01

    Different drug combinations consisting of cholinolytic and a cholinesterase (ChE) reactivator provide greater therapeutic efficacy in acute organophosphorus (OP) poisoning in mice than when used alone. Maximum protection, as determined by a shift of the LD50 for the two OP agents, was observed with the cholinolytic benactyzine. A protection index (P.I.) of 42 was obtained when benactyzine was given along with obidoxime in diisopropylphosphorofluoridate (DFP) intoxication. With the more toxic OP agent soman (o-pinacolylmethylphosphonofluoridate), the same cholinolytic only offered a maximum P.I. of 3.2 when administered with HS-6, another bispyridinium ChE reactivator. This beneficial effect of benactyzine is possibly due to its greater antimuscarinic effect in the central nervous system than atropine or dexetimide. PMID:1935707

  1. Effects of organophosphorus anticholinesterase compounds on brain glucose and energy metabolism. Final summary report, 1 October 1981-29 February 1984

    SciTech Connect

    Medina, M.A.; Miller, A.L.

    1984-09-01

    The effects of Soman and paraoxon on cerebral metabolic rate (CMRg) and the levels of various metabolites in rate brain were investigated. In non-convulsing animals, 0.8 of the paraoxon LD50 and 0.5 of the Soman LD50 tended to lower CMRg. A higher dose of Soman, 0.8-0.95 of the LD50, resulted in convulsive seizures in some but not all of the animals. In convulsing rats the CMRg and lactate levels were elevated primarily in the cortex and thalamus/basal ganglia. Decreased ATP and glucose levels with an elevated CMRg and lactate concentration was observed in the cortex, suggesting that Soman may be uncoupling oxidative phosphorylation. Pretreatment with atropine prevented the behavioral manifestations and the elevated CMRg but not the hyperglycemia produced by an 0.8 LD50 dose of Soman. These results suggest that Soman-induced convulsions are similar to those produced by other central nervous system (CNS) excitatory agents in that only certain brain regions are affected. The use of atropine to block the CNS disturbances produced by Soman appears to be effective also does not result in the extensive depression of CMRg observed with TAB, a mixture of trimedoxime, atropine and benactyzine.

  2. Differential binding of bispyridinium oxime drugs with acetylcholinesterase

    PubMed Central

    Kesharwani, Manoj K; Ganguly, Bishwajit; Das, Amit; Bandyopadhyay, Tusar

    2010-01-01

    Aim: To performe a time-dependent topographical delineation of protein-drug interactions to gain molecular insight into the supremacy of Ortho-7 over HI-6 in reactivating tabun-conjugated mouse acetylcholinesterase (mAChE). Methods: We conducted all-atom steered molecular dynamics simulations of the two protein-drug complexes. Through a host of protein-drug interaction parameters (rupture force profiles, hydrogen bonds, water bridges, hydrophobic interactions), geometrical, and orientation ordering of the drugs, we monitored the enzyme's response during the release of the drugs from its active-site. Results: The results show the preferential binding of the drugs with the enzyme. The pyridinium ring of HI-6 shows excellent complementary binding with the peripheral anionic site, whereas one of two identical pyridinium rings of Ortho-7 has excellent binding compatibility in the enzyme active-site where it can orchestrate the reactivation process. We found that the active pyridinium ring of HI-6 undergoes a complete turn along the active site axis, directed away from the active-site region during the course of the simulation. Conclusion: Due to excellent cooperative binding of Ortho-7, as rendered by several cation-π interactions with the active-site gorge of the enzyme, Ortho-7 may be a more efficient reactivator than HI-6. Our work supports the growing body of evidence that the efficacy of the drugs is due to the differential bindings of the oximes with AChE and can aid to the rational design of oxime drugs. PMID:20140002

  3. Evaluation of oxime efficacy in nerve agent poisoning: Development of a kinetic-based dynamic model

    SciTech Connect

    Worek, Franz . E-mail: FranzWorek@Bundeswehr.org; Szinicz, Ladislaus; Eyer, Peter; Thiermann, Horst

    2005-12-15

    The widespread use of organophosphorus compounds (OP) as pesticides and the repeated misuse of highly toxic OP as chemical warfare agents (nerve agents) emphasize the necessity for the development of effective medical countermeasures. Standard treatment with atropine and the established acetylcholinesterase (AChE) reactivators, obidoxime and pralidoxime, is considered to be ineffective with certain nerve agents due to low oxime effectiveness. From obvious ethical reasons only animal experiments can be used to evaluate new oximes as nerve agent antidotes. However, the extrapolation of data from animal to humans is hampered by marked species differences. Since reactivation of OP-inhibited AChE is considered to be the main mechanism of action of oximes, human erythrocyte AChE can be exploited to test the efficacy of new oximes. By combining enzyme kinetics (inhibition, reactivation, aging) with OP toxicokinetics and oxime pharmacokinetics a dynamic in vitro model was developed which allows the calculation of AChE activities at different scenarios. This model was validated with data from pesticide-poisoned patients and simulations were performed for intravenous and percutaneous nerve agent exposure and intramuscular oxime treatment using published data. The model presented may serve as a tool for defining effective oxime concentrations and for optimizing oxime treatment. In addition, this model can be useful for the development of meaningful therapeutic animal models.

  4. Atropine maintenance dosage in patients with severe organophosphate pesticide poisoning.

    PubMed

    Thiermann, Horst; Steinritz, Dirk; Worek, Franz; Radtke, Maria; Eyer, Peter; Eyer, Florian; Felgenhauer, Norbert; Zilker, Thomas

    2011-09-25

    Although the importance of atropine in therapy of organophosphate (OP) poisoning is generally recognized, its dosing is a matter of debate. A retrospective analysis of atropine dosing was undertaken in 34 patients who had been enrolled in a clinical study assessing obidoxime effectiveness in OP-poisoning. All patients were severely intoxicated (suicidal attempts) and required artificial ventilation. Atropine was administered routinely by intensive care physicians for life-threatening muscarinic symptoms, with the recommendation to favor low dosage. The pharmacological active enantiomere S-hyoscyamine was determined by a radioreceptor assay. When RBC-AChE activity ranged between 10% and 30%, S-hyoscyamine plasma concentrations of approx. 5 nmol L⁻¹ were sufficient. This concentration could be maintained with about 0.005 mg h⁻¹ kg⁻¹ atropine. Only when RBC-AChE was completely inhibited, therapy of cholinergic crisis required atropine doses up to 0.06 mg h⁻¹ kg⁻¹. Elimination half-life of S-hyoscyamine was 1.5 h, showing occasionally a second slow elimination phase with t(½)=12 h. Malignant arrhythmias were observed in some 10% of our cases, which occurred late and often in the absence of relevant glandular cholinergic signs, when the S-hyoscyamine concentration was below 2.5 nmol L⁻¹. Arrhythmias mostly resolved on reinstitution of atropine.

  5. Highly sensitive electrochemiluminescenc assay of acetylcholinesterase activity based on dual biomarkers using Pd-Au nanowires as immobilization platform.

    PubMed

    Ye, Cui; Wang, Min-Qiang; Zhong, Xia; Chen, Shihong; Chai, Yaqin; Yuan, Ruo

    2016-05-15

    One-dimensional Pd-Au nanowires (Pd-Au NWs) were prepared and applied to fabricate an electrochemiluminescence (ECL) biosensor for the detection of acetylcholinesterase (AChE) activity. Compared with single-component of Pd or Au, the bimetallic nanocomposite of Pd-Au NWs offers a larger surface area for the immobilization of enzyme, and displays superior electrocatalytic activity and efficient electron transport capacity. In the presence of AChE and choline oxidase (ChOx), acetylcholine (ATCl) is hydrolyzed by AChE to generate thiocholine, then thiocholine is catalyzed by ChOx to produce H2O2 in situ, which serves as the coreactant to effectively enhance the ECL intensity in luminol-ECL system. The detection principle is based on the inhibited AChE and reactivated AChE as dual biomarkers, in which AChE was inhibited by organophosphorus (OP) agents, and then reactivated by obidoxime. Such dual biomarkers method can achieve credible evaluation for AChE activity via providing AChE activity before and after reactivation. The liner range for AChE activity detection was from 0.025 U L(-1) to 25 KU L(-1) with a low detection limit down to 0.0083 U L(-1). PMID:26686921

  6. Recent advances in evaluation of oxime efficacy in nerve agent poisoning by in vitro analysis

    SciTech Connect

    Worek, F. . E-mail: FranzWorek@Bundeswehr.org; Eyer, P.; Aurbek, N.; Szinicz, L.; Thiermann, H.

    2007-03-15

    The availability of highly toxic organophosphorus (OP) warfare agents (nerve agents) underlines the necessity for an effective medical treatment. Acute OP toxicity is primarily caused by inhibition of acetylcholinesterase (AChE). Reactivators (oximes) of inhibited AChE are a mainstay of treatment, however, the commercially available compounds, obidoxime and pralidoxime, are considered to be rather ineffective against various nerve agents, e.g. soman and cyclosarin. This led to the synthesis and investigation of numerous oximes in the past decades. Reactivation of OP-inhibited AChE is considered to be the most important reaction of oximes. Clinical data from studies with pesticide-poisoned patients support the assumption that the various reactions between AChE, OP and oxime, i.e. inhibition, reactivation and aging, can be investigated in vitro with human AChE. In contrast to animal experiments such in vitro studies with human tissue enable the evaluation of oxime efficacy without being affected by species differences. In the past few years numerous in vitro studies were performed by different groups with a large number of oximes and methods were developed for extrapolating in vitro data to different scenarios of human nerve agent poisoning. The present status in the evaluation of new oximes as antidotes against nerve agent poisoning will be discussed.

  7. Highly sensitive electrochemiluminescenc assay of acetylcholinesterase activity based on dual biomarkers using Pd-Au nanowires as immobilization platform.

    PubMed

    Ye, Cui; Wang, Min-Qiang; Zhong, Xia; Chen, Shihong; Chai, Yaqin; Yuan, Ruo

    2016-05-15

    One-dimensional Pd-Au nanowires (Pd-Au NWs) were prepared and applied to fabricate an electrochemiluminescence (ECL) biosensor for the detection of acetylcholinesterase (AChE) activity. Compared with single-component of Pd or Au, the bimetallic nanocomposite of Pd-Au NWs offers a larger surface area for the immobilization of enzyme, and displays superior electrocatalytic activity and efficient electron transport capacity. In the presence of AChE and choline oxidase (ChOx), acetylcholine (ATCl) is hydrolyzed by AChE to generate thiocholine, then thiocholine is catalyzed by ChOx to produce H2O2 in situ, which serves as the coreactant to effectively enhance the ECL intensity in luminol-ECL system. The detection principle is based on the inhibited AChE and reactivated AChE as dual biomarkers, in which AChE was inhibited by organophosphorus (OP) agents, and then reactivated by obidoxime. Such dual biomarkers method can achieve credible evaluation for AChE activity via providing AChE activity before and after reactivation. The liner range for AChE activity detection was from 0.025 U L(-1) to 25 KU L(-1) with a low detection limit down to 0.0083 U L(-1).

  8. The value of novel oximes for treatment of poisoning by organophosphorus compounds.

    PubMed

    Worek, Franz; Thiermann, Horst

    2013-08-01

    Poisoning by organophosphorus compounds (OP) still is a major therapeutic problem. Intentional OP pesticide poisoning results in up to 300.000 deaths each year and highly toxic OP nerve agents pose a permanent threat for the civilian population and military forces. The therapeutic value of clinically used oximes, pralidoxime, obidoxime and TMB-4, in human OP pesticide poisoning is under debate. Moreover, these oximes lack efficacy in poisoning by various nerve agents. An innumerable number of novel oximes have been synthesized in the past five decades to provide more effective oximes and compounds with improved blood-brain-barrier penetration. Novel compounds were tested with largely different experimental protocols in vitro and in animals in vivo. The lack of comparable experimental conditions and the absence of human in vivo studies hamper a well-founded evaluation of the available data. At present, it appears that only a small number of (bispyridinium) oximes show superior potency and efficacy against individual OP. However, until now, no oxime with sufficient broad-spectrum activity against structurally different OP pesticides and nerve agents is available. An interim solution may be the combination of two oximes with overlapping reactivation spectrum. In conclusion, the unsatisfying situation calls for studies with standardized and comparable experimental conditions in order to allow a sound assessment of available and novel oximes.

  9. Adamantyl tenocyclidines--adjuvant therapy in poisoning with organophosphorus compounds and carbamates.

    PubMed

    Skare, Danko; Radić, Bozica; Lucić, Ana; Peraica, Maja; Domijan, Ana-Marija; Milković-Kraus, Sanja; Bradamante, Vlasta; Jukić, Ivan

    2002-04-01

    The objective of this study was to evaluate the efficacy of thienyl phencyclidine (tenocyclidine, TCP) and its newly synthesized adamantyl derivatives containing piperidine (TAPIP), pyrolidine (TAPIR) and morpholine (TAMORF) groups, which were tested with or without standard therapy in mice poisoned with organophosphates (OPs) and carbamates. These compounds with potential activity at the N-methyl- D-aspartate and muscarinic receptors showed low acute toxicity, having LD50 values varying from 106.00 mg/kg (TCP) to >504.00 mg/kg body weight (TAMORF). TCP and its adamantyl derivatives were administered intraperitoneally (2.5 mg/kg body weight) together with atropine (10.0 mg/kg body weight) and with or without 1/4 LD50 of the oxime HI-6. Each compound administered with atropine had a therapeutic effect against poisoning with carbamates propoxur, aldicarb and Ro 02-0683 (protective ratio of tenocyclidines was from 3.99 LD50 of aldicarb to >16.00 LD50 for propoxur). However, the efficacy of those compounds in combination with atropine was lower against poisoning with the OP insecticide dichlorvos (DDVP) and chemical warfare agents soman and tabun. In soman-poisoned mice, the best therapeutic effects were obtained with the combination of HI-6 plus atropine and test compounds, with protective ratios being from 5.40 to 7.12 LD50 of soman. The results suggest that TCP and adamantyl tenocyclidines could be used in combination with atropine as antidotes in carbamate poisoning and as adjuvant therapy to HI-6 and atropine in soman poisoning.

  10. The effect of oxime reactivators on muscarinic receptors: functional and binding examinations.

    PubMed

    Soukup, O; Kumar, U K; Proska, J; Bratova, L; Adem, A; Jun, D; Fusek, J; Kuca, K; Tobin, G

    2011-05-01

    The antidotal treatment of organophosphorus poisoning is still a problematic issue since no versatile antidote has been developed yet. In our study, we focused on an interesting property, which does not relate to the reactivation of inhibited acetylcholinesterase (AChE) of some oximes, but refers to their anti-muscarinic effects which may contribute considerably to their treatment efficacy. One standard reactivator (HI-6) and two new compounds (K027 and K203) have been investigated for their antimuscarinic properties. Anti-muscarinic effects were studies by means of an in vitro stimulated atrium preparation (functional test), the [(3)H]-QNB binding assay and G-protein coupled receptor assay (GPCR, beta-Arrestin Assay). Based on the functional data HI-6 demonstrates the highest anti-muscarinic effect. However, only when comparing [(3)H]-QNB binding results and GPCR data, K203 shows a very promising compound with regard to anti-muscarinic potency. The therapeutic impact of these findings has been discussed.

  11. Novel nonquaternary reactivators showing reactivation efficiency for soman-inhibited human acetylcholinesterase.

    PubMed

    Wei, Zhao; Liu, Yan-Qin; Wang, Yong-An; Li, Wan-Hua; Zhou, Xin-Bo; Zhao, Jian; Huang, Chun-Qian; Li, Xing-Zhou; Liu, Jia; Zheng, Zhi-Bing; Li, Song

    2016-03-30

    Soman is a highly toxic nerve agent with strong inhibition of acetylcholinesterase (AChE), but of the few reactivators showing antidotal efficiency for soman-inhibited AChE presently are all permanently charged cationic oximes with poor penetration of the blood-brain barrier. To overcome this problem, uncharged reactivators have been designed and synthesized, but few of them were efficient for treating soman poisoning. Herein, we used a dual site biding strategy to develop more efficient uncharged reactivators. The ortho-hydroxylbenzaldoximes were chosen as reactivation ligands of AChE to prevent the secondary poisoning of AChE, and simple aromatic groups were used as peripheral site ligands of AChE, which were linked to the oximes in a similar way as that found in the reactivator HI-6. The in vitro experiment demonstrated that some of the resulting conjugates have robust activity against soman-inhibited AChE, and oxime 8b was highlighted as the most efficient one. Although not good as HI-6 in vitro, these new compounds hold promise for development of more efficient centrally acting reactivators for soman poisoning due to their novel nonquaternary structures, which are predicted to be able to cross the blood-brain barrier. PMID:26809136

  12. Effects of intracellular pH on ATP-sensitive K+ channels in mouse pancreatic beta-cells.

    PubMed Central

    Proks, P; Takano, M; Ashcroft, F M

    1994-01-01

    1. The effects of intracellular pH (pHi) on the ATP-sensitive K+ channel (K+ATP channel) from mouse pancreatic beta-cells were examined in inside-out patches exposed to symmetrical 140 mM K+ solutions. 2. The relationship between channel activity and pHi was described by the Hill equation with half-maximal inhibition (Ki) at pHi 6.25 and a Hill coefficient of 3.7. 3. Following exposure to pHi < 6.8, channel activity did not recover to its original level. Subsequent application of trypsin to the intracellular membrane surface restored channel activity to its initial level or above. 4. At -60 mV the relationship between pHi and the single-channel current amplitude was described by a modified Hill equation with a Hill coefficient of 2.1, half-maximal inhibition at pHi 6.48 and a maximum inhibition of 18.5%. 5. A decrease in pHi reduced the extent of channel inhibition by ATP: Ki was 18 microM at pH 7.2 and 33 microM at pH 6.4. The Hill coefficient was also reduced, being 1.65 at pH 7.2 and 1.17 at pH 6.4. 6. When channel activity was plotted as a function of ATP4- (rather than total ATP) there was no effect of pHi on the relationship. This suggests that ATP4- is the inhibitory ion species and that the effects of reducing pHi are due to the lowered concentration of ATP4-. 7. Changes in external pH had little effect on either single-channel or whole-cell K+ATP currents. 8. The effects of pHi do not support a role for H+ in linking glucose metabolism to K+ATP channel inhibition in pancreatic beta-cells. PMID:8189391

  13. LC-UV and LC-MS evaluation of stress degradation behaviour of avizafone.

    PubMed

    Breton, D; Buret, D; Mendes-Oustric, A C; Chaimbault, P; Lafosse, M; Clair, P

    2006-06-16

    It has been known for many years that benzodiazepine compounds effectively antagonize seizures induced by organophosphorous nerve agents. In the event of poisoning, a combination of three drugs is commonly used: an anticholinergic drug (e.g. atropine), an oxime used as cholinesterase reactivator (e.g. pralidoxime or HI-6) and an anticonvulsant (i.e. benzodiazepine). Most of anticholinergics and oximes are freely soluble in water, whereas many benzodiazepines are not. However, a water-soluble prodrug form of diazepam, avizafone, has been adopted by French armed forces for the immediate treatment of nerve agent seizure. The degradation behaviour of this new drug was investigated under different stress degradation conditions (hydrolytic, oxidative, photolytic and thermal) as recommended by International Conference on Harmonization. Successful separation of the active pharmaceutical ingredient from decomposition products formed under stress conditions was achieved using liquid chromatography. The method was validated with respect to specificity, linearity, precision and accuracy.

  14. Amino acid residues controlling reactivation of organophosphonyl conjugates of acetylcholinesterase by mono- and bisquaternary oximes

    SciTech Connect

    Ashani, Y.; Radic, Z.; Tsigelny, I.; Vellom, D.C.; Pickering, N.A.

    1995-03-17

    Single and multiple site mutants of recombinant mouse acetyicholinesterase (rMoAChE) were inhibited with racemic 7-(methylethoxyphosphinyloxy)- 1-methylquinolinium iodide (MEPQ) and the resulting mixture of two enantiomers, CH3PR,S(O) (OC2H5)-AChE(EMPR,S AChE), were subjected to reactivation with 2-(hydrox- yiminomethyl) -1 -methylpyridinium methanesulfonate (P2S) and 1- (2-hydroxyiminomethyl- 1` -pyridinium)-3- (4`-carbamoyl-1- pyridinium)-2-oxapropane dichloride (HI-6). Kinetic analysis of the reactivation profiles revealed biphasic behavior with an approximate 1:1 ratio of two presumed reactivatable enantiomeric components. Equilibrium dissociation and kinetic rate constants for reactivation of site-specific mutant enzymes were compared with those obtained for wild-type rMoAChE, tissue-derived Torpedo AChE and human plasma butyrylcholinesterase.

  15. Pharmacokinetic profile and quantitation of protection against soman poisoning by the antinicotinic compound MB327 in the guinea-pig.

    PubMed

    Price, Matthew E; Docx, Cerys J; Rice, Helen; Fairhall, Sarah J; Poole, Sarah J C; Bird, Michael; Whiley, Luke; Flint, Daniel P; Green, A Christopher; Timperley, Christopher M; Tattersall, John E H

    2016-02-26

    Current organophosphorus nerve agent medical countermeasures do not directly address the nicotinic effects of poisoning. A series of antinicotinic bispyridinium compounds has been synthesized in our laboratory and screened in vitro. Their actions can include open-channel block at the nicotinic receptor which may contribute to their efficacy. The current lead compound from these studies, MB327 1,1'-(propane-1,3-diyl)bis(4-tert-butylpyridinium) as either the diiodide (I2) or dimethanesulfonate (DMS) has been examined in vivo for efficacy against nerve agent poisoning. MB327 I2 (0-113mgkg(-1)) or the oxime HI-6 DMS (0-100mgkg(- 1)), in combination with atropine and avizafone (each at 3mgkg(-1)) was administered to guinea-pigs 1min following soman poisoning. Treatment increased the LD50 of soman in a dose-dependent manner. The increase was statistically significant (p<0.01) at the 33.9mgkg(-1) (MB327) or 30mgkg(-1) (HI-6) dose with a comparable degree of protection obtained for both compounds. Following administration of 10mgkg(-1) (i.m.), MB327 DMS reached plasma Cmax of 22μM at 12min with an elimination t1/2 of 22min. In an adverse effect study, in the absence of nerve agent poisoning, a dose of 100mgkg(-1) or higher of MB327 DMS was lethal to the guinea-pigs. A lower dose of MB327 DMS (30mgkg(-1)) caused flaccid paralysis accompanied by respiratory impairment. Respiration normalised by 30min, although the animals remained incapacitated to 4h. MB327 or related compounds may be of utility in treatment of nerve agent poisoning as a component of therapy with atropine, anticonvulsant and oxime, or alternatively as an infusion under medical supervision.

  16. Immobilization of Russian VX skin depots by localized cooling: implications for decontamination and medical countermeasures.

    PubMed

    Mikler, J; Tenn, C; Worek, F; Reiter, G; Thiermann, H; Garrett, M; Bohnert, S; Sawyer, T W

    2011-09-25

    The chemical weapon nerve agent known as Russian VX (VR) is a potent organophosphorus (OP) compound that is much less studied than its VX analogue with respect to toxicity, as well as to the effectiveness of several known countermeasures against it. An anaesthetized domestic swine model was utilized to assess several approaches in mitigating its toxicity, including the utility of cooling VR treated skin to increase the therapeutic window for treatment. The 6h LD₅₀ for VR topically applied on the ear was 100 μg/kg. Treatment of VR exposed animals (5 × LD₅₀) with pralidoxime (2PAM) very poorly regenerated inhibited blood cholinesterase activity, but was partially effective in preventing signs of OP poisoning and increasing survival. In contrast, treatment with the Hagedorn oxime HI-6 reactivated cholinesterase, eliminated all signs of poisoning and prevented death. Decontamination with the Reactive Skin Decontaminant Lotion (RSDL) 15 min after VR exposure was completely effective in preventing death. Cooling of the VR exposure sites for 2 or 6h prevented signs of OP poisoning and death during the cooling period. However, these animals died very quickly after the cessation of cooling, unless they were treated with oxime or decontaminated with RSDL. Blood analyses showed that cooling of agent exposure sites delayed the entry of VR into the bloodstream. Medical treatment with HI-6 and to a lesser extent 2PAM, or decontamination with RSDL are effective in protecting against the toxic effects of cutaneous exposure to VR. Immobilizing this agent (and related compounds) within the dermal reservoir by cooling the exposure sites, dramatically increases the therapeutic window in which these medical countermeasures are effective.

  17. Immobilization of Russian VX skin depots by localized cooling: implications for decontamination and medical countermeasures.

    PubMed

    Mikler, J; Tenn, C; Worek, F; Reiter, G; Thiermann, H; Garrett, M; Bohnert, S; Sawyer, T W

    2011-09-25

    The chemical weapon nerve agent known as Russian VX (VR) is a potent organophosphorus (OP) compound that is much less studied than its VX analogue with respect to toxicity, as well as to the effectiveness of several known countermeasures against it. An anaesthetized domestic swine model was utilized to assess several approaches in mitigating its toxicity, including the utility of cooling VR treated skin to increase the therapeutic window for treatment. The 6h LD₅₀ for VR topically applied on the ear was 100 μg/kg. Treatment of VR exposed animals (5 × LD₅₀) with pralidoxime (2PAM) very poorly regenerated inhibited blood cholinesterase activity, but was partially effective in preventing signs of OP poisoning and increasing survival. In contrast, treatment with the Hagedorn oxime HI-6 reactivated cholinesterase, eliminated all signs of poisoning and prevented death. Decontamination with the Reactive Skin Decontaminant Lotion (RSDL) 15 min after VR exposure was completely effective in preventing death. Cooling of the VR exposure sites for 2 or 6h prevented signs of OP poisoning and death during the cooling period. However, these animals died very quickly after the cessation of cooling, unless they were treated with oxime or decontaminated with RSDL. Blood analyses showed that cooling of agent exposure sites delayed the entry of VR into the bloodstream. Medical treatment with HI-6 and to a lesser extent 2PAM, or decontamination with RSDL are effective in protecting against the toxic effects of cutaneous exposure to VR. Immobilizing this agent (and related compounds) within the dermal reservoir by cooling the exposure sites, dramatically increases the therapeutic window in which these medical countermeasures are effective. PMID:21704135

  18. Organophosphate poisoning in the developed world - a single centre experience from here to the millennium.

    PubMed

    Hrabetz, Heidi; Thiermann, Horst; Felgenhauer, Norbert; Zilker, Thomas; Haller, Bernhard; Nährig, Jörg; Saugel, Bernd; Eyer, Florian

    2013-12-01

    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

  19. Signs of cyclosarin-induced neurotoxicity and its pharmacological treatment with quaternary pyridinium-oximes reactivators.

    PubMed

    Krejcova-Kunesova, Gabriela; Bartosova, Lucie; Kuca, Kamil

    2005-12-01

    Cyclosarin (GF-agent; O-cyclohexylmethylfluorophosphonate) belongs to highly toxic organophosphorus compounds. Potential for exposure to chemical warfare organophosphosphorus nerve agents, such as cyclosarin exists on the battlefield, or in the civilian sector as a threat by a terrorist group, as well as an accident as part of current demilitarization efforts. Cyclosarin was not in a front of scientific interest for long time. The research interest was increased after Operation Desert Shield and Desert Storm with the possibility (later confirmed by the UN special commission) that cyclosarin constituted the Iraqi chemical agent inventory. In this study, the neurotoxicity of cyclosarin and therapeutic efficacy of three oximes [HI-6(1-(2-hydroxyiminomethylpyridinium)-3-(4-carbamoylpyridinium)-2-oxa-propane dichloride), BI-6(2-hydroxyiminomethylpyridinium)-4-(4-carbamoylpyridinium)-but-2-ene dibromide), HS-6(2-hydroxyiminomethylpyridinium)-3-(3-carbamoylpyridinium)-2-oxa-propane dichloride)] as acetylcholinesterase reactivators in combination with atropine was studied in rats. The therapy was administered intramusculary (i.m.) 1 min after i.m. GF-agent challenge (1 LD50). Testing of cyclosarin-induced neurotoxicity progress was carried out using the method of Functional observational battery (FOB). The experimental animals were observed at 24 h and 7 days following cyclosarin administration. The results were compared to the condition of control rats that received physiological solution instead of cyclosarin and treatment. All tested antidotal compounds induced neuroprotective efficacy, because decrease of neurotoxicity signs was recorded. There were no poisoned experimental group treated with atropine only, because our preliminary study showed no therapeutical effect of atropine alone. Cyclosarin caused a marked statistically significant change in most of the neurobehavioral parameters (FOB) at 24 h and 7 days after exposure, compared to the saline control group

  20. Interdependent regulation of intracellular acidification and SHP-1 in apoptosis.

    PubMed

    Thangaraju, M; Sharma, K; Liu, D; Shen, S H; Srikant, C B

    1999-04-01

    The G protein-coupled receptor agonist somatostatin (SST)-induces apoptosis in MCF-7 human breast cancer cells. This is associated with induction of wild-type p53, Bax, and an acidic endonuclease. We have shown recently that its cytotoxic signaling is mediated via membrane-associated SHP-1 and is dependent on decrease in intracellular pH (pHi) to 6.5. Here we investigated the relationship between intracellular acidification and SHP-1 in cytotoxic signaling. Clamping of pHi at 7.25 by the proton-ionophore nigericin abolished SST-signaled apoptosis without affecting its ability to regulate SHP-1, p53, and Bax. Apoptosis could be induced by nigericin clamping of pHi to 6.5. Such acidification-induced apoptosis was not observed at pHi <6.0 or >6.7. pHi-dependent apoptosis was associated with the translocation of SHP-1 to the membrane, enhanced in cells overexpressing SHP-1, and was abolished by its inactive mutant SHP-1C455S. Acidification caused by inhibition of Na+/H+ exchanger and H+ ATPase (pHi = 6.55 and 6.65, respectively) also triggered apoptosis. The effect of concurrent inhibition of Na+/H+ exchanger and H(+)-ATPase on pHi and apoptosis was comparable with that of SST. Acidification-induced, SHP-1-dependent apoptosis occurred in breast cancer cell lines in which SST was cytotoxic (MCF-7 and T47D) or not (MDA-MB-231). We conclude that: (a) SST-induced SHP-1-dependent acidification occurs subsequent to or independent of the induction of p53 and Bax; (b) SST-induced intracellular acidification may arise due to inhibition of Na+/H+ exchanger and H(+)-ATPase; and (c) SHP-1 is necessary not only for agonist-induced acidification but also for the execution of acidification-dependent apoptosis. We suggest that combined targeting of SHP-1 and intracellular acidification may lead to a novel strategy of anticancer therapy bypassing the need for receptor-mediated signaling.

  1. Potassium depletion increases luminal Na+/H+ exchange and basolateral Na+:CO3=:HCO3- cotransport in rat renal cortex

    SciTech Connect

    Soleimani, M.; Bergman, J.A.; Hosford, M.A.; McKinney, T.D. )

    1990-10-01

    Most HCO3- reabsorption in proximal tubules occurs via electroneutral Na+/H+ exchange in brush border membranes (BBMS) and electrogenic Na+:CO3=:HCO3- cotransport in basolateral membranes (BLMS). Since potassium depletion (KD) increases HCO3- reabsorption in proximal tubules, we evaluated these transport systems using BBM and BLM vesicles, respectively, from control (C) and KD rats. Feeding rats a potassium deficient diet for 3-4 wk resulted in lower plasma (K+) (2.94 mEq/liter, KD vs. 4.47 C), and higher arterial pH (7.51 KD vs. 7.39 C). KD rats gained less weight than C but had higher renal cortical weight. Influx of 1 mM 22Na+ at 5 s (pHo 7.5, pHi 6.0, 10% CO2, 90% N2) into BLM vesicles was 44% higher in the KD group compared to C with no difference in equilibrium uptake. The increment in Na+ influx in the KD group was DIDS sensitive, suggesting that Na+:CO3=:HCO3- cotransport accounted for the observed differences. Kinetic analysis of Na+ influx showed a Km of 8.2 mM in KD vs. 7.6 mM in C and Vmax of 278 nmol/min/mg protein in KD vs. 177 nmol/min/mg protein in C. Influx of 1 mM 22Na+ at 5 s (pHo 7.5, pHi 6.0) into BBM vesicles was 34% higher in the KD group compared to C with no difference in equilibrium uptake. The increment in Na+ influx in the KD group was amiloride sensitive, suggesting that Na+/H+ exchange was responsible for the observed differences. Kinetic analysis of Na+ influx showed a Km of 6.2 mM in KD vs. 7.1 mM in C and Vmax of 209 nmol/min/mg protein in KD vs. 144 nmol/min/mg protein in C. Uptakes of Na(+)-dependent (3H)glucose into BBM and (14C)succinate into BLM vesicles were not different in KD and C groups, suggesting that the Na+/H+ exchanger and Na+:CO3=:HCO3- cotransporter activities were specifically altered in KD.

  2. Inhibition of the voltage-dependent chloride channel of Torpedo electric organ by diisopropylfluorophosphate and its reversal by oximes

    SciTech Connect

    Abalis, I.M.; Chiang, P.K.; Wirtz, R.A.; Andre, R.G.

    1986-05-01

    Diisopropylfluorophosphate (DFP), a potent organophosphate inhibitor of cholinesterases, was found to inhibit the specific binding of (/sup 35/S)t-butylbicyclophosphorothionate (TBPS), specific chloride channels ligand, to the electric organ membranes of Torpedo, with a Ki of 21 +/- 3 ..mu..M. The binding sites of (/sup 35/S)TBPS in the Torpedo membranes were found not to be GABA receptors or nicotinic acetylcholine receptors as previously described. Interestingly, a stimulation of the binding of (/sup 35/S)TBPS was observed in the presence of atropine and three oximes, monopyridinium oxime 2-PAM, bispyridinium bis-oxime TMB-4 and H-oxime HI-6. The maximal stimulation was 300-500% of control, after which, the stimulation was reversed at higher concentrations. The three oximes protected by more than 95% the inhibition by 1 mM DFP of the binding of (/sup 35/S)TBPS to the voltage-dependent chloride channel. However, atropine protected only 20% of the inhibited channel. These results, thus, suggest that the protection against the toxic effects of DFP or other anticholinesterase agents by the tested oximes may not be solely a result of the reactivation of cholinesterases but also the protection of the voltage-dependent chloride channel.

  3. Anticonvulsant actions of anticholinergic drugs in soman poisoning. (Reannouncement with new availability information)

    SciTech Connect

    Capacio, B.R.; Shih, T.M.

    1991-12-31

    The acute effects of the organophosphorus cholinesterase inhibitor soman include hypersecretions, convulsions, and death. The purpose of this study was to evaluate the anticholinergic compounds, aprophen, atropine sulfate, azaprophen, benactyzine, benztropine, biperiden, scopolamine HBr, and trihexyphenidyl for their efficacy in preventing soman-induced hypersecretions and convulsions. Male rats were injected with the oxime HI-6 (125 mg/kg, i.p.), to increase survival time, along with various intramuscular doses of the anticholinergics 30 min prior to a dose of soman that produced 100% convulsions. Signs of intoxication as well as the time-to-onset of convulsions were observed. The calculated anticonvulsant median effective dose values were 0.18, 0.33, 0.36, 0.55, 2.17, 2.30, 2.45, and 31.09 micro mol per kilogram for scopolamine HBr, biperiden, trihexyphenidy, benactyzine, benztropine, azaprophen, aprophen, and atropine sulfate, respectively. The same rank order by potency for inhibition of hypersecretions among these compounds was observed.

  4. Structures of paraoxon-inhibited human acetylcholinesterase reveal perturbations of the acyl loop and the dimer interface.

    PubMed

    Franklin, Matthew C; Rudolph, Michael J; Ginter, Christopher; Cassidy, Michael S; Cheung, Jonah

    2016-09-01

    Irreversible inhibition of the essential nervous system enzyme acetylcholinesterase by organophosphate nerve agents and pesticides may quickly lead to death. Oxime reactivators currently used as antidotes are generally less effective against pesticide exposure than nerve agent exposure, and pesticide exposure constitutes the majority of cases of organophosphate poisoning in the world. The current lack of published structural data specific to human acetylcholinesterase organophosphate-inhibited and oxime-bound states hinders development of effective medical treatments. We have solved structures of human acetylcholinesterase in different states in complex with the organophosphate insecticide, paraoxon, and oximes. Reaction with paraoxon results in a highly perturbed acyl loop that causes a narrowing of the gorge in the peripheral site that may impede entry of reactivators. This appears characteristic of acetylcholinesterase inhibition by organophosphate insecticides but not nerve agents. Additional changes seen at the dimer interface are novel and provide further examples of the disruptive effect of paraoxon. Ternary structures of paraoxon-inhibited human acetylcholinesterase in complex with the oximes HI6 and 2-PAM reveals relatively poor positioning for reactivation. This study provides a structural foundation for improved reactivator design for the treatment of organophosphate intoxication. Proteins 2016; 84:1246-1256. © 2016 Wiley Periodicals, Inc. PMID:27191504

  5. Cl-HCO3 exchange in choroid plexus: analysis by the DMO method for cell pH

    SciTech Connect

    Johanson, C.E.; Parandoosh, Z.; Smith, Q.R.

    1985-10-01

    ( UC)DMO distribution was used to measure steady-state intracellular pH (pHi) and (HCO3)i in adult rat choroid plexus (CP) incubated in synthetic cerebrospinal fluid (CSF) for 30 min. In controls at 37 degrees C, mean pHi (6.95 at PCO2 = 30 mmHg) was close to corresponding in vivo values; and (HCO3)i/(HCO3)csf, i.e., rHCO3, was 0.37. At normal (HCO3)csf = 18 mM, cell HCO3 was accumulated threefold above electrochemical equilibrium. (HCO3)i decreased proportionally with (HCO3)csf, as the latter was altered from 47 to 9 mM; in severe extracellular acidosis (( HCO3)csf = 3.7 mM), (HCO3)i was not reduced further and so rHCO3 rose to 0.66. Except in low (HCO3)csf, acetazolamide and ouabain (10(-4) M) caused small depletion of cell HCO3. 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid lowered (HCO3)i by 60%, thus decreasing rHCO3 (0.16) and rCl (0.25) to values close to estimated equilibrium distribution (0.15). Augmented PCO2 associated with temperature reduction to 15 degrees C elevated (HCO3)i, thereby increasing rHCO3 (to 0.66) as well as rCl. Anion distribution ratios indicate heteroanion exchange in mammalian CP.

  6. The therapeutic use of localized cooling in the treatment of VX poisoning.

    PubMed

    Sawyer, T W; Mikler, J; Worek, F; Reiter, G; Thiermann, H; Tenn, C; Weatherby, K; Bohnert, S

    2011-07-01

    The organophosphate (OP) nerve agent VX is a weaponized chemical warfare agent that has also been used by terrorists against civilians. This contact poison produces characteristic signs of OP poisoning, including miosis, salivation, mastication, dysrhythmias and respiratory distress prior to death. Although successful treatment of OP poisoning can be obtained through decontamination and/or oxime reactivation of agent-inhibited cholinesterase, medical countermeasures that increase the therapeutic window for these measures would be of benefit. An anaesthetized swine model was utilized to examine the effects of lethal VX exposure to the skin, followed by cooling the exposure site prior to decontamination or treatment. The cooling was simply accomplished by using crushed ice in grip-seal plastic bags applied to the exposure sites. Cooling of skin exposed to lethal doses of VX significantly increased the window of opportunity for successful decontamination using the Reactive Skin Decontaminant Lotion(®) (RSDL(®)) or treatment with the oxime antidotes HI-6 and 2PAM. Analyses of blood VX levels showed that cooling acted to slow or prevent the entry of VX into the bloodstream from the skin. If the exposure site is known, the simple and non-invasive application of cooling provides a safe means with which to dramatically increase the therapeutic window in which decontamination and/or antidote treatment against VX are life-saving.

  7. Caramiphen edisylate as adjunct to standard therapy attenuates soman-induced seizures and cognitive deficits in rats.

    PubMed

    Schultz, M K; Wright, L K M; de Araujo Furtado, M; Stone, M F; Moffett, M C; Kelley, N R; Bourne, A R; Lumeh, W Z; Schultz, C R; Schwartz, J E; Lumley, L A

    2014-01-01

    The progression of epileptiform activity following soman (GD) exposure is characterized by a period of excessive cholinergic activity followed by excessive glutamatergic activity resulting in status epilepticus, which may lead to neuropathological damage and behavioral deficits. Caramiphen edisylate is an anticholinergic drug with antiglutamatergic properties, which conceptually may be a beneficial therapeutic approach to the treatment of nerve agent exposure. In the present study, rats were exposed to 1.2 LD50 GD or saline, treated with atropine sulfate (2mg/kg, im) and HI-6 (93.6mg/kg, im) 1min after GD exposure, and monitored for seizure activity. Rats were treated with diazepam (10mg/kg, sc) and caramiphen (0, 20 or 100mg/kg, im) 30min after seizure onset. Following GD exposure, performance was evaluated using a battery of behavioral tests to assess motor coordination and function, sensorimotor gating, and cognitive function. Caramiphen as adjunct to diazepam treatment attenuated GD-induced seizure activity, neuropathological damage, and cognitive deficits compared to diazepam alone, but did not attenuate the GD-induced sensorimotor gating impairment. These findings show that physiological, behavioral, and neuropathological effects of GD exposure can be attenuated by treatment with caramiphen as an adjunct to therapy, even if administration is delayed to 30min after seizure onset.

  8. The therapeutic use of localized cooling in the treatment of VX poisoning.

    PubMed

    Sawyer, T W; Mikler, J; Worek, F; Reiter, G; Thiermann, H; Tenn, C; Weatherby, K; Bohnert, S

    2011-07-01

    The organophosphate (OP) nerve agent VX is a weaponized chemical warfare agent that has also been used by terrorists against civilians. This contact poison produces characteristic signs of OP poisoning, including miosis, salivation, mastication, dysrhythmias and respiratory distress prior to death. Although successful treatment of OP poisoning can be obtained through decontamination and/or oxime reactivation of agent-inhibited cholinesterase, medical countermeasures that increase the therapeutic window for these measures would be of benefit. An anaesthetized swine model was utilized to examine the effects of lethal VX exposure to the skin, followed by cooling the exposure site prior to decontamination or treatment. The cooling was simply accomplished by using crushed ice in grip-seal plastic bags applied to the exposure sites. Cooling of skin exposed to lethal doses of VX significantly increased the window of opportunity for successful decontamination using the Reactive Skin Decontaminant Lotion(®) (RSDL(®)) or treatment with the oxime antidotes HI-6 and 2PAM. Analyses of blood VX levels showed that cooling acted to slow or prevent the entry of VX into the bloodstream from the skin. If the exposure site is known, the simple and non-invasive application of cooling provides a safe means with which to dramatically increase the therapeutic window in which decontamination and/or antidote treatment against VX are life-saving. PMID:21530621

  9. [Chemical weapons: antidotes. View about the real means, perspectives].

    PubMed

    Ricordel, I; Meunier, J

    2000-01-01

    Chemical methods remain a credible threat in 1999. The doctrine for their use not only includes the battlefield but also domestic terrorism as was disclosed during the Tokyo metro attempt in 1995. International Treaties have not yet proven their efficacy. The arsenal of chemical weapons has changed little since the second World War but is now dispersed into many high-risk zones throughout the world. There has also been little change in antidotes: therapeutic prevention with pyridostigmine against organo-phosphorus compounds, protective treatment for seizure-induced brain lesions using anticonvulsants in association with oxime for acetylcholinesterase reactivation, and atropine are combined in a three-compartment syringe. Preventive measures against vesicants and other suffocating or toxic intracellular substances (CN, AsH(3), fluorocarbons.) can only be achieved with protective skin covering or protective breathing devices. There is no specific treatment and we often have to use symptomatic medications. Future perspectives include: phosphotriesterases as organo-phosphorus scavengers, huperzine as pretreatment and gacyclidine (GCK 11) which would effectively complete emergency multiple drug therapy against nerve agents. A new two-compartment syringe is now prepared with atropine, avisafone and HI6 or pralidoxine. A gel made of cyclodextrines for external and eventually internal use is under study.

  10. Distribution, sources and health risk assessment of mercury in kindergarten dust

    NASA Astrophysics Data System (ADS)

    Sun, Guangyi; Li, Zhonggen; Bi, Xiangyang; Chen, Yupeng; Lu, Shuangfang; Yuan, Xin

    2013-07-01

    Mercury (Hg) contamination in urban area is a hot issue in environmental research. In this study, the distribution, sources and health risk of Hg in dust from 69 kindergartens in Wuhan, China, were investigated. In comparison with most other cities, the concentrations of total mercury (THg) and methylmercury (MeHg) were significantly elevated, ranging from 0.15 to 10.59 mg kg-1 and from 0.64 to 3.88 μg kg-1, respectively. Among the five different urban areas, the educational area had the highest concentrations of THg and MeHg. The GIS mapping was used to identify the hot-spot areas and assess the potential pollution sources of Hg. The emissions of coal-power plants and coking plants were the main sources of THg in the dust, whereas the contributions of municipal solid waste (MSW) landfills and iron and steel smelting related industries were not significant. However, the emission of MSW landfills was considered to be an important source of MeHg in the studied area. The result of health risk assessment indicated that there was a high adverse health effect of the kindergarten dust in terms of Hg contamination on the children living in the educational area (Hazard index (HI) = 6.89).

  11. [Ethanol fermentation from Jerusalem artichoke tubers by a genetically-modified Saccharomyces cerevisiae strain capable of secreting inulinase].

    PubMed

    Li, Nannan; Yuan, Wenjie; Wang, Na; Xin, Chengxun; Ge, Xumeng; Bai, Fengwu

    2011-07-01

    Ethanol fermentation from Jerusalem artichoke tubers by recombinant Saccharomyces cerevisiae strains expressing the inulinase gene (inu) from Kluyveromyces marxianus was investigated. The inu native and pgk promoters were used to drive the expression of the inu gene, and the inulinase was expressed as an extracellular enzyme. All positive clones (confirmed by PCR) were able to express inulinase as measured by enzyme activity in the culture supernatant, among which two clones HI6/6 and HPI6/3 were selected, and their inulinase activity and ethanol fermentation performance were compared with their wild type. The inulinase activities of 86 and 23.8 U/mL were achieved, which were 4.6-fold and 1.5-fold higher than that of the wild type. Furthermore, ethanol fermentation was carried out with the recombinants and medium containing 200 g/L raw Jerusalem artichoke meal, and ethanol concentrations of 55 g/L and 52 g/L were obtained, with ethanol yields of 0.495 and 0.453, respectively, equivalent to 96.9% and 88.6% of the theoretical value. PMID:22016987

  12. Functional Analysis and Molecular Docking studies of Medicinal Compounds for AChE and BChE in Alzheimer’s Disease and Type 2 Diabetes Mellitus

    PubMed Central

    Kaladhar, Dowluru SVGK; Yarla, Nagendra Sastry; Anusha, N.

    2013-01-01

    Acetylcholinesterase and Butyrylcholinesterase share unravelling link with components of metabolic syndromes that’s characterised by low levels of HDL cholesterol, obesity, high fast aldohexose levels, hyper-trigliceridaemia and high blood pressure, by regulation of cholinergic transmission and therefore the enzyme activity within a living system. The phosphomotifs associated with amino acid and tyrosine binding motifs in AChE and BChE were known to be common. Phylogenetic tree was constructed to these proteins usinf UPGMA and Maximum Likelihood methods in MEGA software has shown interaction of AChE and BChE with ageing diseases like Alzheimer’s disease and Diabetes. AChE has shown closely related to BChE, retinol dehydrogenase and β-polypeptide. The present studies is also accomplished that AChE, BChE, COLQ, HAND1, APP, NLGN2 and NGF proteins has interactions with diseases such as Alzheimer’s and D2M using Pathwaylinker and STRING. Medicinal compounds like Ortho-7, Dibucaine and HI-6 are predicted as good targets for modeled AChE and BChE proteins based on docking studies. Hence perceptive studies of cholinesterase structure and the biological mechanisms of inhibition are necessary for effective drug development. PMID:23936743

  13. Interactions of external and internal H+ and Na+ with Na+/Na+ and Na+/H+ exchange of rabbit red cells: evidence for a common pathway.

    PubMed

    Morgan, K; Canessa, M

    1990-12-01

    We have studied the kinetic properties of rabbit red cell (RRBC) Na+/Na+ and Na+/H+ exchanges (EXC) in order to define whether or not both transport functions are conducted by the same molecule. The strategy has been to determine the interactions of Na+ and H+ at the internal (i) and external (o) sites for both exchanges modes. RRBC containing varying Nai and Hi were prepared by nystatin and DIDS treatment of acid-loaded cells. Na+/Na+ EXC was measured as Nao-stimulated Na+ efflux and Na+/H+ EXC as Nao-stimulated H+ efflux and delta pHo-stimulated Na+ influx into acid-loaded cells. The activation of Na+/Na+ EXC by Nao at pHi 7.4 did not follow simple hyperbolic kinetics. Testing of different kinetic models to obtain the best fit for the experimental data indicated the presence of high (Km 2.2 mM) and low affinity (Km 108 mM) sites for a single- or two-carrier system. The activation of Na+/H+ EXC by Nao (pHi 6.6, Nai less than 1 mM) also showed high (Km 11 mM) and low (Km 248 mM) affinity sites. External H+ competitively inhibited Na+/Na+ EXC at the low affinity Nao site (KH 52 nM) while internally H+ were competitive inhibitors (pK 6.7) at low Nai and allosteric activators (pK 7.0) at high Nai. Na+/H+ EXC was also inhibited by acid pHo and allosterically activated by Hi (pK 6.4). We also established the presence of a Nai regulatory site which activates Na+/H+ and Na+/Na+ EXC modifying the affinity for Nao of both pathways. At low Nai, Na+/Na+ EXC was inhibited by acid pHi and Na+/H+ stimulated but at high Nai, Na+/Na+ EXC was stimulated and Na+/H+ inhibited being the sum of both pathways kept constant. Both exchange modes were activated by two classes of Nao sites, cis-inhibited by external Ho, allosterically modified by the binding of H+ to a Hi regulatory site and regulated by Nai. These findings are consistent with Na+/Na+ EXC being a mode of operation of the Na+/H+ exchanger. Na+/H+ EXC was partially inhibited (80-100%) by dimethyl-amiloride (DMA) but basal or

  14. LY293558 prevents soman-induced pathophysiological alterations in the basolateral amygdala and the development of anxiety.

    PubMed

    Prager, Eric M; Figueiredo, Taiza H; Long, Robert P; Aroniadou-Anderjaska, Vassiliki; Apland, James P; Braga, Maria F M

    2015-02-01

    Exposure to nerve agents can cause brain damage due to prolonged seizure activity, producing long-term behavioral deficits. We have previously shown that LY293558, a GluK1/AMPA receptor antagonist, is a very effective anticonvulsant and neuroprotectant against nerve agent exposure. In the present study, we examined whether the protection against nerve agent-induced seizures and neuropathology conferred by LY293558 translates into protection against pathophysiological alterations in the basolateral amygdala (BLA) and the development of anxiety, which is the most prevalent behavioral deficit resulting from exposure. LY293558 (15 mg/kg) was administered to rats, along with atropine and HI-6, at 20 min after exposure to soman (1.2 × LD50). At 24 h, 7 days, and 30 days after exposure, soman-exposed rats who did not receive LY293558 had reduced but prolonged evoked field potentials in the BLA, as well as increased paired-pulse ratio, suggesting neuronal damage and impaired synaptic inhibition; rats who received LY293558 did not differ from controls in these parameters. Long-term potentiation of synaptic transmission was impaired at 7 days after exposure in the soman-exposed rats who did not receive anticonvulsant treatment, but not in the LY293558-treated rats. Anxiety-like behavior assessed by the open field and acoustic startle response tests was increased in the soman-exposed rats at 30 and 90 days after exposure, while rats treated with LY293558 did not differ from controls. Along with our previous findings, the present data demonstrate the remarkable efficacy of LY293558 in counteracting nerve agent-induced seizures, neuropathology, pathophysiological alterations in the BLA, and anxiety-related behavioral deficits.

  15. Cell to cell communication and pH in the frog lens.

    PubMed

    Mathias, R T; Riquelme, G; Rae, J L

    1991-12-01

    Fiber cells of the lens are electrically and diffusionally interconnected through extensive gap junctions. These junctions allow fluxes of small solutes to move between inner cells and peripheral cells, where the majority of transmembrane transport takes place. We describe here a method utilizing two intracellular microelectrodes to measure the cell to cell resistance between fiber cells at any given distance into the intact lens. We also use ion-sensitive microelectrodes to record intracellular pH at various depths in the intact lens. We find that gap junctions connecting inner fiber cells differ in pH sensitivity as well as normal coupling resistance from those connecting peripheral cells. The transition occurs in a zone between 500 and 650 microns into the lens. Fiber cells peripheral to this zone have a specific coupling resistance of 1.1 omega cm2, whereas those inside have a specific coupling resistance of 2.7 omega cm2. However, when the cytoplasm of fiber cells is acidified by bubbling with CO2, peripheral cells uncouple and the cell to cell resistance goes up more than 40-fold, whereas junctions inside this zone are essentially unaffected by changes in intracellular pH. In a normal frog lens, the intracellular pH in fiber cells near the lens surface is 7.02, a value significantly alkaline to electrochemical equilibrium. Our data suggest that Na/H exchange and perhaps other Na gradient-dependent mechanisms in the peripheral cells maintain this transmembrane gradient. Deep in the lens, the fiber cell cytoplasm is significantly more acidic (pHi 6.81) due to influx of hydrogen across the inner fiber cell membranes and production of H+ by the inner fiber cells. Because of the normally acid cytoplasm of interior fiber cells, their loss of gap junctional sensitivity to pH may be essential to lens survival.

  16. Oxime-induced reactivation of carboxylesterase inhibited by organophosphorus compounds

    SciTech Connect

    Maxwell, D.M.; Lieske, C.N.; Brecht, K.M.

    1994-06-01

    A structure-activity analysis of the ability of oximes to reactivate rat plasma carboxylesterase (CaE) that was inhibited by organophosphorus (OP) compounds revealed that uncharged oximes, such as 2,3-butanedione monoxime (diacetylmonoxime) or monoisonitrosoacetone, were better reactivators than cationic oximes. Cationic oximes that are excellent reactivators of OP-inhibited acetylcholinesterase, such as pyridine-2-aldoxime or the bis-pyridine aldoximes, HI-6 and TMB. 4, produced poor reactivation of OP-inhibited CaE. The best uncharged reactivator was 2,3. butanedione monoxime, which produced complete reactivation at 0.3 mM in 2 h of CaE that was inhibited by phosphinates, alkoxy-containing phosphates, and alkoxy-containing phosphonates. Complete reactivation of CaE could be achieved even after inhibition by phosphonates with highly branched alkoxy groups, such as sarin and soman, that undergo rapid aging with acetylcholinesterase. CaE that was inhibited by phosphonates or phosphates that contained aryloxy groups were reactivated to a lesser extent. The cause of this decreased reactivation appears to be an oxime-induced aging reaction that competes with the reactivation reaction. This oxime-induced aging reaction is accelerated by electron-withdrawing substituents on the aryloxy groups of phosphonates and by the presence of multiple aryloxy groups on phosphates. Thus, reactivation and aging of OP-inhibited CaE differ from the same processes for OP- inhibited acetylcholinesterase in both their oxime specificity and inhibitor specificity and, presumably, in their underlying mechanisms.

  17. RXP-E: A CX43-BINDING PEPTIDE THAT PREVENTS ACTION POTENTIAL PROPAGATION BLOCK

    PubMed Central

    Lewandowski, Rebecca; Procida, Kristina; Vaidyanathan, Ravi; Coombs, Wanda; Jalife, Jose; Nielsen, Morten S.; Taffet, Steven M.; Delmar, Mario

    2009-01-01

    Gap junctions (GJs) provide a low-resistance pathway for cardiac electrical propagation. The role of GJ regulation in arrhythmia is unclear, partly due to limited availability of pharmacological tools. Recently, we showed that a peptide called “RXP-E” binds to the carboxyl terminal of connexin43 (Cx43) and prevents chemically-induced uncoupling in Cx43-expressing N2a cells. Here, pull-down experiments show RXP-E binding to adult cardiac Cx43. Patch-clamp studies revealed that RXP-E prevented heptanol-induced and acidification-induced uncoupling in pairs of neonatal rat ventricular myocytes (NRVM’s). Separately, RXP-E was concatenated to a cytoplasmic transduction peptide for cytoplasmic translocation (CTP-RXP-E). The effect of RXP-E on action potential (AP) propagation was assessed by high resolution optical mapping in monolayers of NRVM’s, containing ~20% of randomly distributed myofibroblasts. In contrast to control experiments, when heptanol (2 mmol/L) was added to the superfusate of monolayers loaded with CTP-RXP-E, AP propagation was maintained, albeit at a slower velocity. Similarly, intracellular acidification (pHi=6.2) caused a loss of AP propagation in control monolayers; however, propagation was maintained in CTP-RXP-E treated cells, though at a slower rate. Patch clamp experiments revealed that RXP-E did not prevent heptanol-induced block of sodium currents, nor did it alter voltage dependence or amplitude of Kir2.1/Kir2.3 currents. RXP-E is the first synthetic molecule known to: (1) bind cardiac Cx43; (2) prevent heptanol and acidification-induced uncoupling of cardiac GJ’s and 3) preserve AP propagation among cardiac myocytes. RXP-E can be used to characterize the role of GJs in the function of multicellular systems, including the heart. PMID:18669919

  18. Human plasma-derived BuChE as a stoichiometric bioscavenger for treatment of nerve agent poisoning.

    PubMed

    Mumford, Helen; Docx, Cerys J; Price, Matthew E; Green, A Christopher; Tattersall, John E H; Armstrong, Stuart J

    2013-03-25

    Potent organophosphorous (OP) agents, such as VX, are hazardous by absorption through the skin and are resistant to conventional pharmacological antidotal treatments. The residence time of a stoichiometric bioscavenger, human butyrylcholinesterase (huBuChE), in the plasma more closely matches that of VX than do the residence times of conventional therapy drugs (oxime, anti-muscarinic, anticonvulsant). Intramuscular (i.m.) huBuChE afforded almost complete protection when administered prior to the onset of observable cholinergic signs of VX poisoning, but once signs of poisoning became evident the efficacy of i.m. huBuChE decreased. A combination of nerve agent therapy drugs (oxime, anti-muscarinic, anticonvulsant) with huBuChE (i.m.) protected 100% (8/8) of guinea-pigs from a lethal dose of VX (0.74 mg/kg) to 48 h, even when administered on signs of poisoning. Survival was presumed to be due to immediate alleviation of the cholinergic crisis by the conventional pharmacological treatment drugs, in conjunction with bioscavenger that prevented further absorbed agent reaching the AChE targets. Evidence to support this proposed mechanism of action was obtained from PKPD experiments in which multiple blood samples and microdialysate samples were collected from individual conscious ambulatory animals. Plasma concentrations of intramuscularly-administered atropine, diazepam and HI-6 reached a peak within 15 min and were eliminated rapidly within 4h. Plasma concentrations of huBuChE administered by the i.m. route took approximately 24h to reach a peak, but were well-maintained over the subsequent 7days. Thus, the pharmacological therapy rapidly treated the initial signs of poisoning, whilst the bioscavenger provided prolonged protection by neutralising further nerve agent entering the bloodstream and preventing it from reaching the target organs.

  19. Surgical correction of 639 pectus excavatum cases via the Nuss procedure

    PubMed Central

    Zhang, Dong-Kun; Tang, Ji-Ming; Ben, Xiao-Song; Xie, Liang; Zhou, Hai-Yu; Ye, Xiong; Zhou, Zi-Hao; Shi, Rui-Qing; Xiao, Pu

    2015-01-01

    Background To review the clinical experience and short- to middle-term effects of the Nuss procedure for correction of pectus excavatum (PE). Methods From September 2006 to August 2014, 639 patients with PE were treated using the Nuss procedure. Of these, 546 were male and 93 were female. The mean age was 15.3±5.8 years (2.5-49 years). Preoperative chest CT scans Haller index (HI) was 4.3±1.7 (2.9-17.4), with 75 cases of mild PE (HI <3.2), 114 cases of moderate PE (HI 3.2-3.5), 393 cases of severe PE (HI 3.6-6.0), and 57 cases of extremely severe PE (HI >6.0). Results A total of 638 patients successfully completed the surgery, an 11-year-old male patient who died after the surgery had undergone ventricular septal defect closure surgery through a sternal incision 7 years ago. The mean operative time was 64.3±41.7 min (40-310 min). Excluding the patient who died, the average blood loss was 24.5±17.8 mL (10-160 mL). The average length of postoperative hospital stay was 5.2±2.9 days (4-36 days). A total of 484 cases (75.7%) required 1 steel bar insertion, 153 cases (24.0%) required 2 steel bars, and 2 cases (0.3%) required 3 bars. Postoperative evaluation of the surgery outcomes revealed the following: excellent in 504 cases, good in 105, fair in 28 and poor in 2, good quality rate was 95.3%. Conclusions Correction of PE via the Nuss procedure is minimally invasive and simple to perform with good short and mid-term effects, while long-term efficacy remains to be determined. PMID:26543607

  20. Comparison of oxime reactivation and aging of nerve agent-inhibited monkey and human acetylcholinesterases.

    PubMed

    Luo, Chunyuan; Tong, Min; Maxwell, Donald M; Saxena, Ashima

    2008-09-25

    Non-human primates are valuable animal models that are used for the evaluation of nerve agent toxicity as well as antidotes and results from animal experiments are extrapolated to humans. It has been demonstrated that the efficacy of an oxime primarily depends on its ability to reactivate nerve agent-inhibited acetylcholinesterase (AChE). If the in vitro oxime reactivation of nerve agent-inhibited animal AChE is similar to that of human AChE, it is likely that the results of an in vivo animal study will reliably extrapolate to humans. Therefore, the goal of this study was to compare the aging and reactivation of human and different monkey (Rhesus, Cynomolgus, and African Green) AChEs inhibited by GF, GD, and VR. The oximes examined include the traditional oxime 2-PAM, two H-oximes HI-6 and HLo-7, and the new candidate oxime MMB4. Results indicate that oxime reactivation of all three monkey AChEs was very similar to human AChE. The maximum difference in the second-order reactivation rate constant between human and three monkey AChEs or between AChEs from different monkey species was 5-fold. Aging rate constants of GF-, GD-, and VR-inhibited monkey AChEs were very similar to human AChE except for GF-inhibited monkey AChEs, which aged 2-3 times faster than the human enzyme. The results of this study suggest that all three monkey species are suitable animal models for nerve agent antidote evaluation since monkey AChEs possess similar biochemical/pharmacological properties to human AChE.

  1. Changes in Plasma Aldosterone and Electrolytes Following High-Volume and High-Intensity Resistance Exercise Protocols in Trained Men.

    PubMed

    Boone, Carleigh H; Hoffman, Jay R; Gonzalez, Adam M; Jajtner, Adam R; Townsend, Jeremy R; Baker, Kayla M; Fukuda, David H; Stout, Jeffrey R

    2016-07-01

    Boone, CH, Hoffman, JR, Gonzalez, AM, Jajtner, AR, Townsend, JR, Baker, KM, Fukuda, DH, and Stout, JR. Changes in plasma aldosterone and electrolytes following high-volume and high-intensity resistance exercise protocols in trained men. J Strength Cond Res 30(7): 1917-1923, 2016-Program variables such as training intensity, volume, and rest interval length are known to elicit distinct hormonal, metabolic, and physical responses. However, little is known regarding resistance exercise (RE) program design and the fluid regulatory response. This investigation aimed to compare the plasma aldosterone (ALD), electrolyte, plasma volume (PV), and osmolality (Posm) responses following high-volume (HV; 4-6 × 10-12 reps, 70% 1 repetition maximum [1RM], 60-s rest) and high-intensity (HI; 6 × 3-5 reps, 90% 1RM, 180-second rest) RE protocols. Ten experienced, resistance-trained men (24.7 ± 3.4 years; 90.1 ± 11.3 kg; 176.0 ± 4.9 cm) performed each protocol in a random, counterbalanced order. Blood samples were obtained at baseline (BL), immediately (IP), 30 minutes (30P), and 1 hour (1H) postexercise. Significant trial × time interactions (p < 0.01) were observed in Posm, sodium (Na), and potassium (K), whereas a trend (p = 0.06) was observed for ALD. The PV shift from BL-30P was greater than BL-IP and BL-1H (p ≤ 0.05), but no significant between-trial differences were noted. Comparisons between RE protocols revealed significantly greater (p ≤ 0.05) elevations during HV vs. HI in Posm at IP, 30P, and 1H; and Na at IP and 30P. During HV, significant reductions (p ≤ 0.05) were noted in K at IP compared with HI. Area under the curve analysis indicates a trend (p = 0.07) toward a higher ALD response following HV compared with HI. Results of this study indicate that high-volume, moderate-intensity resistance exercise seems to augment the fluid regulatory response to a greater extent than low-volume, high-intensity training. PMID:27331915

  2. The regulation of intracellular pH studied by 31P- and 1H-NMR spectroscopy in superfused guinea-pig cerebral cortex slices.

    PubMed

    Brooks, K J; Bachelard, H S

    1992-10-01

    (1) The intracellular pH (pHi) of superfused slices of guinea-pig cerebral cortex was measured in 31P-NMR spectra using the chemical shifts of intracellular inorganic phosphate (Pi) and of 2-deoxyglucose 6-phosphate (DOG6P). The pHi was found to be 7.30 +/- 0.04 (SD, n = 15) in bicarbonate-buffered medium and 7.20 +/- 0.05 (n = 10, P < 0.001) in bicarbonate-free HEPES buffer of the same pH (7.4). (2) Decreases in pHe below 7.05 resulted in pHi falling to similar values, with a decrease in the energy state. There was no change in intracellular lactate as assessed by 1H-NMR. (3) The tissues showed an ability to buffer higher pH: increasing pHe to 8.0 had no effect on pHi, PCr or lactate. (4) In order to characterize possible mechanisms of pH regulation in the tissue, the recovery from acid insult was investigated under various conditions. Initially pHi was decreased to 6.44 +/- 0.15 (n = 15) by exposure to media containing 6 mM bicarbonate gassed with O2/CO2, 80:20 (pHe 6.4). When this medium was replaced by normal bicarbonate buffer (pH 7.4) there was full recovery of pHi to 7.31 +/- 0.05 (n = 15), whereas replacing the buffer with HEPES resulted in incomplete recovery of pHi to 6.88 +/- 0.15 (n = 15, P < 0.001). (5) In the presence of the carbonic anhydrase inhibitor, acetazolamide (1 mM), or the sodium/proton exchange inhibitor, amiloride (1 mM), there was an incomplete return of pHi to the control value (pHi 6.90 +/- 0.20, n = 5, P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1303163

  3. Increased Na+/H+ exchanger activity on the apical surface of a cilium-deficient cortical collecting duct principal cell model of polycystic kidney disease

    PubMed Central

    Olteanu, Dragos; Liu, Xiaofen; Liu, Wen; Roper, Venus C.; Sharma, Neeraj; Yoder, Bradley K.; Satlin, Lisa M.; Schwiebert, Erik M.

    2012-01-01

    Pathophysiological anomalies in autosomal dominant and recessive forms of polycystic kidney disease (PKD) may derive from impaired function/formation of the apical central monocilium of ductal epithelia such as that seen in the Oak Ridge polycystic kidney or orpk (Ift88Tg737Rpw) mouse and its immortalized cell models for the renal collecting duct. According to a previous study, Na/H exchanger (NHE) activity may contribute to hyperabsorptive Na+ movement in cilium-deficient (“mutant”) cortical collecting duct principal cell monolayers derived from the orpk mice compared with cilium-competent (“rescued”) monolayers. To examine NHE activity, we measured intracellular pH (pHi) by fluorescence imaging with the pH-sensitive dye BCECF, and used a custom-designed perfusion chamber to control the apical and basolateral solutions independently. Both mutant and rescued monolayers exhibited basolateral Na+-dependent acid-base transporter activity in the nominal absence of CO2/HCO3−. However, only the mutant cells displayed appreciable apical Na+-induced pHi recoveries from NH4+ prepulse-induced acid loads. Similar results were obtained with isolated, perfused collecting ducts from orpk vs. wild-type mice. The pHi dependence of basolateral cariporide/HOE-694-sensitive NHE activity under our experimental conditions was similar in both mutant and rescued cells, and 3.5- to 4.5-fold greater than apical HOE-sensitive NHE activity in the mutant cells (pHi 6.23–6.68). Increased apical NHE activity correlated with increased apical NHE1 expression in the mutant cells, and increased apical localization in collecting ducts of kidney sections from orpk vs. control mice. A kidney-specific conditional cilium-knockout mouse produced a more acidic urine compared with wild-type littermates and became alkalotic by 28 days of age. This study provides the first description of altered NHE activity, and an associated acid-base anomaly in any form of PKD. PMID:22301060

  4. LY293558 prevents soman-induced pathophysiological alterations in the basolateral amygdala and the development of anxiety

    PubMed Central

    Prager, Eric M.; Figueiredo, Taiza H.; Long, Robert P.; Aroniadou-Anderjaska, Vassiliki; Apland, James P.; Braga, Maria F.M.

    2014-01-01

    Without timely pharmacological treatment, nerve agent exposure can cause a large number of casualties, as occurred in the recent sarin attack in Syria. Nerve agent-induced seizures are initiated due to inhibition of acetylcholinesterase, but they become quickly refractory to muscarinic antagonists, and their suppression by benzodiazepines can be only temporary. Therefore, novel treatments are necessary to stop seizures and prevent brain damage and the resulting long-term behavioral deficits. We have previously shown that LY293558, a GluK1/AMPA receptor antagonist, is a very effective anticonvulsant and neuroprotectant against nerve agent exposure. In the present study, we examined whether the protection against nerve agent-induced seizures and neuropathology conferred by LY293558 translates into protection against pathophysiological alterations in the basolateral amygdala (BLA) and the development of anxiety, which is the most prevalent behavioral deficit resulting from exposure. LY293558 (15 mg/kg) was administered to rats along with atropine and the oxime HI-6, at 20 min after exposure to soman (1.2 x LD50). At 24 h, 7 days, and 30 days after exposure, soman-exposed rats that did not receive LY293558 had reduced but prolonged evoked field potentials in the BLA, as well as increased paired-pulse ratio, suggesting neuronal damage and impaired synaptic inhibition. In contrast, soman-exposed rats that received LY293558 did not differ from controls in these parameters. Similarly, long-term potentiation of synaptic transmission was impaired at 7 days after exposure in the soman-exposed rats that did not receive anticonvulsant treatment, while this impairment was not present in the LY293558-treated rats. Anxiety-like behavior assessed by the open field and acoustic startle response tests was increased in the soman-exposed rats at 30 and 90 days after exposure, while soman-exposed rats treated with LY293558 did not differ from controls. Along with our previous findings

  5. pH regulation in adult rat carotid body glomus cells. Importance of extracellular pH, sodium, and potassium [published erratum appears in J Gen Physiol 1993 Jan;101(1):following 144

    PubMed Central

    1992-01-01

    The course of intracellular pH (pHi) was followed in superfused (36 degrees C) single glomus (type I) cells of the freshly dissociated adult rat carotid body. The cells had been loaded with the pH-sensitive fluorescent dye 2',7'-(2-carboxyethyl)-5 (and -6)-carboxyfluorescein. The high K(+)-nigericin method was used for calibration. The pHi of the glomus cell at pHo 7.40, without CO2, was 7.23 +/- 0.02 (n = 70); in 5% CO2/25 mM HCO3-, pHi was 7.18 +/- 0.08 (n = 9). The pHi was very sensitive to changes in pHo. Without CO2, delta pHi/delta pHo was 0.85 (pHo 6.20-8.00; 32 cells), while in CO2/HCO3- this ratio was 0.82 irrespective of whether pHo (6.80-7.40; 14 cells) was changed at constant PCO2 or at constant [HCO3-]o. The great pHi sensitivity of the glomus cell to pHo is matched only by that of the human red cell. An active Na+/H+ exchanger (apparent Km = 58 +/- 6 mM) is present in glomus cells: Na+ removal or addition of the amiloride derivative 5- (N,N-hexamethylene)-amiloride induced pHi to fall by as much as 0.9. The membrane of these cells also contains a K+/H+ exchanger. Raising [K+]o from 4.7 to 25, 50, or 140 mM reversibly raised pHi by 0.2, 0.3, and 0.6, respectively. Rb+ had no effect, but in corresponding concentrations of Tl+ alkalinization was much faster than in K+. Reducing [K+]o to 1.5 mM lowered pHi by 0.1. These pHi changes were shown not to be due to changes in membrane voltage, and were even more striking in the absence of Na+. Intrinsic buffering power (amount of strong base required to produce, in the nominal absence of CO2, a small pHi rise) increased from 3 to approximately 21 mM as pHi was lowered, but remained nearly unchanged below pHi 6.60. The fitted expression assumed the presence of one "equivalent" intracellular buffer (pK 6.41, 41 mM). The exceptional pHi sensitivity to pHo suggests that the pHi of the glomus cell is a link in the chemoreceptor's response to external acidity. PMID:1294152

  6. Stratigraphic relationships of Cretaceous and early Tertiary rocks of a part of northwestern San Juan basin

    USGS Publications Warehouse

    Baltz, Elmer Harold

    1953-01-01

    sandstone facies of the Nacimiento and San Jose formations are correlated with similar facies of these formations on the east side of the San Juan Basin. Folding along the borders of the Central basin was completed prior to deposition of the youngest San Joss beds, and they were probably widely distributed outside of the Central Basin in Eocene time. In Pliocene time, the San Juan region was beveled by the San Juan peneplain. Rejuvenation of the San Juan Mountains in late Pliocene time caused erosion in the mountains and deposition of the Bridgetimber gravel in the San Juan Basin. Uplift in Pleistocene time caused large-scale erosion in the Bridge Timber Mountain area and gravel-covered terraces represent the various stages of uplift and erosion. The stratigraphic relationships of uppermost Cretaceous and lower Tertiary rocks in the Bridge Timber Mountain area are similar to recently described relationships of equivalent rocks in other parts of the San Juan Basin. The southwestern lobe of the Pictured Cliffs sandstone was derived from older Cretaceous source areas to the southwest and deposited in the seaway which was retreating northeastward. The northeastern lobe consists of reworked Cretaceous sediments eroded from the flanks of the rising San Juan zone and Sangre de Cristo upwarp and deposited in an arm of the sea which was isolated by uplift of the mountain masses. This arm of the sea was forced to retreat to the southeast as sediments of the Fruitland, Kirtland, Animas, and Ojo Alamo formations were deposited in' the basin. The Animas formation which was derived from hi6hlands to the northeast spread progressively to the southwest and interfingered with lesser amounts of Fruitland and Kirtland sediments derived from the southwest. In latest Cretaceous or earliest Paleocene time folding began along the Hogback 'monocline' in northern and western San Juan Basin and sediments were eroded from the uplifted platforms around the margin of the Central Basin and rede