Reactivation effects of K203 and currently available oximes (obidoxime, HI-6) in combination with atropine on acetylcholinesterase activities in the brain parts of rats poisoned with tabun were studied. The activity was determined by quantitative histochemical and biochemical methods correlating between them very well. The tabun-induced changes in acetylcholinsterase activity as well as in reactivation potency of reactivators used were different in various parts of the brain. Pontomedullar area seems to be important for observed changes following tabun intoxication and its treatment. From the oximes studied, the reactivation effect of K203 was comparable with obidoxime; HI-6 was ineffective. Combination of bio- and histochemical methods allow fine differentiation among the action of different oximes following tabun poisoning.

• MeSH
• chemické bojové látky otrava   MeSH
• cholinesterasy metabolismus   MeSH
• krysa rodu rattus MeSH
• mapování mozku MeSH
• molekulární struktura MeSH
• mozek účinky léků   enzymologie   patologie   MeSH
• neurotoxické syndromy enzymologie   patologie   prevence a kontrola   MeSH
• organofosfáty otrava   MeSH
• oximy aplikace a dávkování   chemie   farmakologie   terapeutické užití   MeSH
• potkani Wistar MeSH
• pyridinové sloučeniny aplikace a dávkování   chemie   farmakologie   terapeutické užití   MeSH
• reaktivátory cholinesterázy aplikace a dávkování   chemie   farmakologie   terapeutické užití   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Organophosphorous compounds cause fatal intoxication based on inhibition of acetylcholinesterase, an essential enzyme of neurosynapses and neuromuscular junctions. There is an obvious need to develop appropriate treatment against them due to their application in agriculture and chemical industry or their misuse in terrorist or war attack. In the Czech army some medicaments have been established to be used against this poisoning; Obidoxime, Methoxime, Atropine and Benactyzine. In present in vitro study we focused on potential cytotoxic and genotoxic effect evaluation of these drugs by the clonogenic and comet assay, respectively. Obtained results show that oximes exhibit pronounced toxic effect, namely obidoxime in term of genotoxicity and methoxime in term of cytotoxicity.

• Klíčová slova
• Obidoxime, Methoxime, Atropine, Benactyzine,
• MeSH
• analýza kolonii tvořících jednotek metody   statistika a číselné údaje   MeSH
• antidota chemie   MeSH
• buňky Hep G2 účinky léků   MeSH
• časové faktory MeSH
• financování organizované MeSH
• kometový test metody   statistika a číselné údaje   MeSH
• organofosfáty otrava   toxicita   MeSH
• otrava farmakoterapie   MeSH
• oximy chemie   MeSH
• poškození DNA účinky léků   MeSH
• reaktivátory cholinesterázy terapeutické užití   MeSH
• Publikační typ
• techniky in vitro MeSH

The ability of the newly developed bispyridinium compound K203 and its fluorinated analogue KR-22836 to reduce tabun-induced acute neurotoxic signs and symptoms was compared with the currently available reactivator of acetylcholinesterase-obidoxime. Tabun-induced neurotoxicity and the neuroprotective effects of all tested oximes in combination with atropine in rats poisoned with tabun at a sublethal dose (200 μg/kg intramuscularly (i.m.); 80% of LD(50) value) were monitored by a functional observational battery at 24 hr after tabun challenge. The results indicate that all tested oximes combined with atropine were able to survive tabun-poisoned rats 24 hr after tabun challenge while one non-treated tabun-poisoned rat died within 24 hr after tabun poisoning. All tested oximes combined with atropine were able to decrease tabun-induced neurotoxicity in the case of sublethal poisoning but they did not eliminate all tabun-induced acute neurotoxic signs and symptoms. While the ability to reduce tabun-induced acute neurotoxicity of obidoxime and K203 was similar, the neuroprotective efficacy of KR-22836 was slightly higher compared to other tested oximes. Thus, the newly developed fluorinated analogue of K203, called KR-22836, is able to slightly increase the neuroprotective effectiveness of antidotal treatment of acute tabun poisonings compared to K203 and currently available obidoxime.

• MeSH
• akutní nemoc MeSH
• autonomní nervový systém účinky léků   MeSH
• chemické bojové látky otrava   MeSH
• chování zvířat účinky léků   MeSH
• hyperkineze chemicky indukované   prevence a kontrola   MeSH
• krysa rodu rattus MeSH
• molekulární struktura MeSH
• neuroprotektivní látky aplikace a dávkování   chemie   terapeutické užití   MeSH
• neurotoxické syndromy etiologie   prevence a kontrola   MeSH
• obidoxim chlorid aplikace a dávkování   chemie   terapeutické užití   MeSH
• organofosfáty otrava   MeSH
• oximy aplikace a dávkování   chemie   terapeutické užití   MeSH
• potkani Wistar MeSH
• pyridinové sloučeniny aplikace a dávkování   chemie   terapeutické užití   MeSH
• svalový tonus účinky léků   MeSH
• výsledek terapie MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH

The influence of the combination of oximes on the reactivating and therapeutic efficacy of antidotal treament of acute tabun poisoning was evaluated. The ability of two combinations of oximes (HI-6 + obidoxime and HI-6 + K203) to reactivate tabun-inhibited acetylcholinesterase and reduce acute toxicity of tabun was compared with the reactivating and therapeutic efficacy of antidotal treatment involving single oxime (HI-6, obidoxime, K203) using in vivo methods. Studies determining percentage of reactivation of tabun-inhibited blood and tissue acetylcholinesterase in poisoned rats showed that the reactivating efficacy of both combinations of oximes is higher than the reactivating efficacy of the most effective individual oxime in blood and diaphragm and comparable with the reactivating effects of the most effective individual oxime in brain. Moreover, both combinations of oximes were found to be slightly more efficacious in the reduction of acute lethal toxic effects in tabun-poisoned mice than the antidotal treatment involving individual oxime. A comparison of reactivating and therapeutic efficacy of individual oximes showed that the newly developed oxime K203 is slightly more effective than commonly used obidoxime and both of them are markedly more effective than the oxime HI-6. Based on the obtained data, we can conclude that the antidotal treatment involving chosen combinations of oximes brings beneficial effects for the potency of antidotal treatment to reactivate tabun-inhibited acetylcholinesterase in rats and to reduce acute toxicity of tabun in mice.

• MeSH
• acetylcholinesterasa MeSH
• antidota terapeutické užití   MeSH
• kombinovaná farmakoterapie MeSH
• krysa rodu rattus MeSH
• myši MeSH
• obidoxim chlorid terapeutické užití   MeSH
• organofosfáty otrava   MeSH
• oximy terapeutické užití   MeSH
• potkani Wistar MeSH
• pyridinové sloučeniny terapeutické užití   MeSH
• reaktivátory cholinesterázy terapeutické užití   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The ability of newly developed oximes (K347, K628) to reduce tabun-induced acute neurotoxic signs and symptoms was compared with currently available oximes (obidoxime, HI-6) using a functional observational battery. The neuroprotective effects of the oximes studied (K347, K628, obidoxime, HI-6) combined with atropine on rats poisoned with tabun at a sublethal dose (220 µg/kg i.m.; 80 % of LD50 value) were evaluated. Tabun-induced neurotoxicity was monitored by a functional observational battery and automatic measurement of motor activity at 24 hours following tabun challenge. The results indicate that all tested oximes combined with atropine enable tabun-poisoned rats to survive 24 hours following tabun challenge. Both newly developed oximes (K347, K628) combined with atropine are able to decrease tabun-induced neurotoxicity in the case of sublethal poisonings but they do not eliminate all tabun-induced acute neurotoxic signs and symptoms. Their ability to decrease the tabun-induced acute neurotoxicity is higher than that of the oxime HI-6 and it is slightly slower than the neuroprotective efficacy of obidoxime. As the neuroprotective potency of both newly developed oximes (K347, K628) is not as high as the potency of obidoxime, they are not a suitable replacement for obidoxime for the treatment of acute tabun poisonings.

• Klíčová slova
• Tabun, Functional observational battery, K347, K628, Obidoxime, HI-6, Rats,
• MeSH
• antidota terapeutické užití   MeSH
• chemické bojové látky otrava   MeSH
• cholinesterasové inhibitory otrava   MeSH
• financování organizované MeSH
• krysa rodu rattus MeSH
• organofosfáty otrava   MeSH
• oximy terapeutické užití   MeSH
• potkani Wistar MeSH
• reaktivátory cholinesterázy terapeutické užití   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH

Bioscavengers are considered as promising antidotes against organophosphate poisoning. We focused on a bacterial phosphotriesterase (PTE) expressed in Escherichia coli. The main disadvantage of this non-human catalytic bioscavenger is its relatively short half-life in the organism and strong immunogenicity after repeated administration. Therefore, we prepared different methoxy polyethylene glycol (MPEG)-conjugated recombinant PTE as a potential catalytic bioscavenger with the aim to improve its biological properties. Enzyme was modified with two linear monofunctional MPEG derivatives with reactive aldehyde group of molecular weight 2 kDa and 5 kDa. We optimized reaction conditions (reagent ratios, temperature and duration of modification reaction) and we prepared homogeneous population of fully modified recombinant PTE with molecular weight around 52 kDa and 76 kDa, respectively. Modified PTE was characterized using SDS-PAGE and MALDI-TOF and by determining K(m) and V(max). We also investigated thermal stability of modified enzyme at 37 degrees C. Based on our results, for future in vivo evaluation of pharmacokinetics and pharmacodynamics properties, we selected recombinant PTE modified with 5 kDa MPEG aldehyde for its superior thermal stability.

• MeSH
• aktivace enzymů MeSH
• aldehydy chemie   MeSH
• antidota chemie   izolace a purifikace   metabolismus   farmakologie   MeSH
• biokatalýza MeSH
• Caulobacteraceae enzymologie   MeSH
• elektroforéza v polyakrylamidovém gelu MeSH
• hydrolasy triesterů kyseliny fosforečné chemie   izolace a purifikace   metabolismus   farmakologie   MeSH
• koncentrace vodíkových iontů MeSH
• organofosfáty metabolismus   otrava   MeSH
• polyethylenglykoly chemie   MeSH
• spektrometrie hmotnostní - ionizace laserem za účasti matrice MeSH
• stabilita enzymů MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Up to now, intensive attempts to synthesize a universal reactivator able to reactivate cholinesterases inhibited by all types of nerve agents/organophosphates were not successful. Therefore, another approach using a combination of two reactivators differently reactivating enzyme was used: in rats poisoned with tabun and treated with combination of atropine (fixed dose) and different doses of trimedoxime and HI-6, changes of acetylcholinesterase activities (blood, diaphragm and different parts of the brain) were studied. An increase of AChE activity was observed following trimedoxime treatment depending on its dose; HI-6 had very low effect. Combination of both oximes showed potentiation of their reactivation efficacy; this potentiation was expressed for peripheral AChE (blood, diaphragm) and some parts of the brain (pontomedullar area, frontal cortex); AChE in the basal ganglia was relatively resistant. These observations suggest that the action of combination of oximes in vivo is different from that observed in vitro.

• MeSH
• acetylcholinesterasa krev   metabolismus   MeSH
• aktivace enzymů účinky léků   MeSH
• centrální nervový systém účinky léků   enzymologie   metabolismus   MeSH
• kombinovaná farmakoterapie MeSH
• krysa rodu rattus MeSH
• organofosfáty otrava   MeSH
• oximy aplikace a dávkování   farmakologie   MeSH
• potkani Wistar MeSH
• pyridinové sloučeniny aplikace a dávkování   farmakologie   MeSH
• reaktivátory cholinesterázy aplikace a dávkování   farmakologie   MeSH
• trimedoxim aplikace a dávkování   farmakologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The studies dealing with mechanism of organophosphates (OP)/nerve agent action, prophylaxis and treatment of intoxications is a very hot topic at present. Though the research is very intensive, unfortunately, up to now, there is not universal or significantly better reactivator sufficiently effective against all nerve agents/OP when compared with presently available oximes (pralidoxime, methoxime, obidoxime, trimedoxime, HI-6). The use of the most effective reactivator (HI-6) using simple type of autoinjector (e.g. ComboPen) is strictly limited because of decomposition of HI-6 in solution. Thanks to better solubility it is clear that another salt of HI-6 (dimethanesulfonate, HI-6 DMS) is more convenient for the use as antidote against nerve agents in the autoinjector than HI-6 chloride (Cl). It was clearly demonstrated that reactivation potency of HI-6 DMS in comparison with HI-6 Cl in vivo was the same and bioavailability of HI-6 DMS is better than that of HI-6 Cl. Three chambered autoinjector allows administration of all three antidotes (atropine, reactivator, diazepam) simultaneously. Moreover, the content of chambers can be changed according to proposed requirements. Possible way to solve the problem of universal reactivator could be the use of two reactivators. Three chambered autoinjector is an ideal device for this purpose.

• MeSH
• antidota terapeutické užití   MeSH
• chemické bojové látky otrava   MeSH
• cholinesterasové inhibitory otrava   MeSH
• financování organizované MeSH
• lidé MeSH
• organofosfáty otrava   MeSH
• oximy terapeutické užití   MeSH
• pyridinové sloučeniny terapeutické užití   MeSH
• reaktivátory cholinesterázy terapeutické užití   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• přehledy MeSH

Prophylactic approaches against intoxication with organophosphates (OP)/nerve agents can be based on following principles: keeping acetylcholinesterase (AChE), the key enzyme for toxic action of OP/nerve agents, intact (protection of cholinesterases) is a basic requirement for effective prophylaxis. It can be reached using simple chemicals such as reversible inhibitors (preferably carbamates), which are able to inhibit AChE reversibly. AChE inhibited by carbamates is resistant to OP/nerve agent inhibition. After spontaneous recovery of the activity, normal AChE serves as a source of the active enzyme. Detoxification is realised by administration of the enzymes splitting the OP or exploitating specific enzymes (cholinesterases). OP/nerve agent is bound to the exogenously administered proteins (enzymes) and, thus, the agent level in the organism is decreased ("scavenger" effect). The antidotes currently used for the treatment of OP poisoning (also simple chemicals) can be tested as prophylactics. This principle can be considered as a treatment "in advance". The problem with their use is the timing, duration and achievement of sufficient levels of these antidotes after the administration. At present, PYRIDOSTIGMINE seems to be common prophylactic antidote; prophylactics PANPAL (tablets with pyridostigmine, trihexyphenidyle and benactyzine), TRANSANT (transdermal patch containing HI-6) are other means introduced into different armies as prophylactics. Future development will be focused on scavengers (cholinesterases and other enzymes) acting before the binding of nerve agent to the target sites, and on other drugs reversible cholinesterase inhibitors (e.g. huperzine A, physostigmine, acridine derivatives etc.) including non-traditional routes of administration.

• MeSH
• acetylcholinesterasa chemie   metabolismus   MeSH
• chemické bojové látky chemie   otrava   MeSH
• cholinergní antagonisté farmakologie   chemie   MeSH
• cholinesterasové inhibitory farmakologie   chemie   otrava   MeSH
• lidé MeSH
• organofosfáty chemie   otrava   MeSH
• otrava prevence a kontrola   MeSH
• reaktivátory cholinesterázy farmakologie   chemie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• práce podpořená grantem MeSH
• přehledy MeSH

The potency of newly developed bispyridinium compounds (K117, K127) to reduce tabun-induced acute neurotoxic signs and symptoms was compared with currently available oxime (obidoxime) using functional observational battery. The neuroprotective effects of atropine alone and atropine combined with one of three bispyridinium oximes (K117, K127, obidoxime) on rats poisoned with tabun at a sublethal dose (180 microg/kg i.m.; 80% of LD(50) value) were studied. Tabun-induced neurotoxicity was monitored using a functional observational battery and automatic measurement of motor activity at 24 h following tabun challenge. The results indicated that all tested oximes combined with atropine enabled tabun-poisoned rats to survive 24 h following tabun challenge while one tabun-poisoned rats died within 24 h after tabun poisoning when the rats were treated with atropine alone. Newly developed oxime K127 combined with atropine was the most effective in decreasing tabun-induced neurotoxicity in the case of sublethal poisonings among all oximes tested. Nevertheless, the differences of neuroprotective efficacy between K127 and obidoxime are not sufficient to replace obidoxime by K127 for the treatment of acute tabun poisonings.

• MeSH
• chemické bojové látky otrava   MeSH
• cholinesterasové inhibitory otrava   MeSH
• krysa rodu rattus MeSH
• neuroprotektivní látky farmakologie   MeSH
• organofosfáty otrava   MeSH
• oximy farmakologie   MeSH
• pohybová aktivita účinky léků   MeSH
• potkani Wistar MeSH
• pyridinové sloučeniny farmakologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• práce podpořená grantem MeSH
• srovnávací studie MeSH