Experimental Substantiation of Inhalation Administration of Pathogenic Therapy of Toxic Convulsive Disorder for Correction of External Respiration Disorders.

We studied the dynamics of respiratory function in rats during intratracheal poisoning with diisopropyl fluorophosphate and pentylenetetrazole in doses corresponding to the LD50 in humans. The maximum of external respiration impairment was recorded in 30 min after poisoning. Administration of diazepam and atropine both separately and in combination during the development of the first signs of poisoning did not significantly affect the respiration parameters, but reduced the incidence of seizures and contributed to a decrease in the rate of animal death. Intratracheal administration of cholinolytic, ß2-adrenomimetic, or glutamate receptors antagonist promoted correction of the respiratory function. It was found that the maximum therapeutic effect in case of diisopropyl fluorophosphates poisoning was achieved after intratracheal administration of ipratropium bromide (0.086 mg/kg), salbutamol (0.086 mg/kg), and MK-801 (0.1 mg/kg), while in case of pentylenetetrazole poisoning, intratracheal administration of ipratropium bromide (0.086 mg/kg) was most effective.

Determination of anti-convulsant and life-preserving capacities of three types of auto-injector therapies against soman intoxication in rats.

More effective countermeasures against nerve-agent poisoning are needed, because current ones do not protect sufficiently, particularly the central nervous system (CNS). The purpose of the present study was to make a comparison of the antidotal capabilities of atropine/obidoxime/diazepam (termed the obidoxime regimen), atropine/HI-6 (1-[([4-(aminocarbonyl)pyridinio]methoxy)methyl]-2-[(hydroxyimino)methyl]pyridinium)/avizafone (termed the HI-6 regimen), and scopolamine/HI-6/physostigmine (termed the physostigmine regimen) against various doses of soman (2, 3, 4 x LD50 ). The results showed that each regimen administered twice (1 min and 5 min after exposure) effectively prevented or terminated epileptiform activity within 10 min. However, the regimens differed markedly in life-saving properties with the physostigmine regimen ranking highest followed in descending order by the HI-6 and obidoxime regimens. Pretreatment with pyridostigmine increased the potency of the HI-6 regimen, but not the obidoxime regimen. The latter regimen administered thrice (1 min, 5 min, and 9 min after exposure) did not compensate for the insufficiency. In half of the rats that lived for 7 days, neuropathology was unexpectedly observed predominantly in the left hemisphere unrelated to whether they seized or not. Local glutamatergic excitotoxic activity may occur even if manifest toxic signs are absent. The physostigmine regimen has excellent antidotal capacity, but the very narrow therapeutic window (< 10 min) makes it unsuitable for use in the field. The HI-6 regimen appears to constitute an efficacious therapy against lower doses of soman (2 and 3 x LD50).

A poison center's ten-year experience with flumazenil administration to acutely poisoned adults.

BACKGROUND: The frequency of seizures among acutely poisoned adults who are administered flumazenil has not been well established. STUDY OBJECTIVE: The objectives of the study were: to determine the frequency of seizures among acutely poisoned adults administered flumazenil; to identify factors associated with seizures; and to determine the mental status of subjects before and after administration of flumazenil. METHODS: This study was a historical case series of acutely poisoned adults reported to a poison control system from 1999 to 2008. Included cases were those involving administration of flumazenil to subjects who were ≥ 18 years of age. Both genders were included. Variables collected included: presence of seizure or death, exposure to a pro-convulsant drug, and mental status before and after flumazenil administration. RESULTS: Over the 10-year period studied, 904 cases were identified that met inclusion criteria. Thirteen subjects (1.4%) developed seizures after flumazenil was administered. One death occurred. There were 293 subjects exposed to a pro-convulsant drug, and 8 of these had seizures after flumazenil administration. Development of seizures after flumazenil administration was significantly associated with exposure to a pro-convulsant drug (odds ratio 3.41; 95% confidence interval 1.13-10.72). Mental status before and after flumazenil administration was available for 546 subjects (60.3%). Of these, 291 (53.3%) became awake after administration of flumazenil. CONCLUSIONS: Flumazenil administration to acutely poisoned adults resulted in a low frequency of seizures and death. Development of seizures was associated with exposure to a pro-convulsant drug. More than half of the subjects for whom mental status was recorded became awake after receiving flumazenil.

Hypertonic mannitol in mice poisoned by a convulsive dose of soman: antilethal activity without neuroprotection.

A convulsive dose of soman induces seizure-related brain damage (SRBD), including cerebral edema (CE) and cell death. In 1993, an American study demonstrated that hypertonic mannitol (Mann) intravenously (i.v.) administered 1 min and 5h post-soman was an effective neuroprotectant in intoxicated rats. Using a similar protocol, we recently failed to reproduce this success in intoxicated mice. In the present study, also performed in mice, the persistence or the amplitude of the osmotic load was increased by reducing the time interval between two injections of Mann or by augmenting the number of injections. Mice were pre-treated with the oxime HI-6 and then intoxicated with a convulsive dose of soman (172 microg/kg). Afterward, they were administered a first i.v. bolus of Mann 20% 1 min post-challenge and a second one either 5, or 2, or 1h after. Additional animals were given either one (1 min post-soman), or two (1 min and 1h post-soman), or three (1 min, 1 and 2h post-soman) series of three injections of Mann at 5 min intervals. Non-intoxicated mice treated with Mann (same protocols as above) and intoxicated mice treated with Mann vehicle (saline) served as controls. At 24h post-intoxication, the survivors were sacrificed and their brains prepared for quantitative histological assessment of cell damage, CE, and ventricle size. Whatever the protocol, Mann had no effect on soman-induced convulsions but did provide considerable antilethal activity. Histologically, Mann did not reduce the cell damage or CE. It even showed a dose-dependent trend toward aggravation of SRBD in some regions and promoted subarachnoid hemorrhages. Conversely, in one of the treatment protocol, it reduced soman-induced enlargement of ventricle size. Although treatment with hypertonic Mann showed some benefit on mortality and ventricle size, it failed to be an effective neuroprotector in soman-intoxicated mice and even increased the detrimental impact of soman at the cerebral level. Therefore, no clear recommendation could be drawn from the present study in view of a possible clinical use of hyperosmolar treatment in the medical management of soman poisoning.

Hyperosmolar treatment of soman-induced brain lesions in mice: evaluation of the effects through diffusion-weighted magnetic resonance imaging and through histology.

PURPOSE: A convulsive dose of soman induces seizure-related brain damage (SRBD), including cerebral edema (CE) and neuronal loss. In the present study on soman-intoxicated mice, we applied diffusion-weighted magnetic resonance imaging (DW-MRI) and quantitative histology, and we measured brain water content to investigate the antiedematous and neuroprotective efficacies of two hyperosmolar treatments: mannitol (Mann) and hypertonic saline (HTS). METHODS: Mice intoxicated with soman (172 microg/kg after a protective pretreatment) were administered 1 min and 5-h post-challenge an i.v. bolus of saline, of Mann or of HTS. 1 day later, mice were examined with DW-MRI and then sacrificed for brain histology. Additional animals were intoxicated and treated similarly for the measurement of the brain water content (dry/wet weight method). RESULTS: In intoxicated controls, a significant decrease of the apparent diffusion coefficient (ADC), numerous damaged (eosinophilic) cells, high edema scores, and a significant increase in brain water content were detected 24-h post-challenge in sensitive brain structures. These soman-induced changes were not significantly modified by treatment with Mann or HTS. CONCLUSIONS: Treatment with hyperosmolar solutions did not reduce the effects of soman on ADC, on cell damage and on CE. Therefore, despite similar treatment protocols, the prominent protection by Mann that was previously demonstrated by others in poisoned rats, was not reproduced in our murine model.

Cerebral edema induced in mice by a convulsive dose of soman. Evaluation through diffusion-weighted magnetic resonance imaging and histology.

PURPOSE: In the present study, diffusion-weighted magnetic resonance imaging (DW-MRI) and histology were used to assess cerebral edema and lesions in mice intoxicated by a convulsive dose of soman, an organophosphate compound acting as an irreversible cholinesterase inhibitor. METHODS: Three hours and 24 h after the intoxication with soman (172 microg/kg), the mice were anesthetized with an isoflurane/N(2)O mixture and their brain examined with DW-MRI. After the imaging sessions, the mice were sacrificed for histological analysis of their brain. RESULTS: A decrease in the apparent diffusion coefficient (ADC) was detected as soon as 3 h after the intoxication and was found strongly enhanced at 24 h. A correlation was obtained between the ADC change and the severity of the overall brain damage (edema and cellular degeneration): the more severe the damage, the stronger the ADC drop. Anesthesia was shown to interrupt soman-induced seizures and to attenuate edema and cell change in certain sensitive brain areas. Finally, brain water content was assessed using the traditional dry/wet weight method. A significant increase of brain water was observed following the intoxication. CONCLUSIONS: The ADC decrease observed in the present study suggests that brain edema in soman poisoning is mainly intracellular and cytotoxic. Since entry of water into the brain was also evidenced, this type of edema is certainly mixed with others (vasogenic, hydrostatic, osmotic). The present study confirms the potential of DW-MRI as a non-invasive tool for monitoring the acute neuropathological consequences (edema and neurodegeneration) of soman-induced seizures.

Assessment of the therapeutic and anticonvulsive efficacy of a drug combination consisting of trihexyphenidyle and HI-6 in soman-poisoned rats.

1. The influence of two anticholinergic drugs (atropine, trihexyphenidyle) on the effectiveness of antidotal treatment to eliminate soman-induced lethal effects and convulsions was studied in rats. 2. The oxime HI-6 when combined with centrally acting anticholinergic drug trihexyphenidyle seems to be more efficacious in the elimination of acute toxic effects of soman than its combination with atropine. 3. The findings support the hypothesis that the choice of the anticholinergic drug is important for the effectiveness of antidotal mixture in the case of antidotal treatment of soman-induced acute poisoning.

Thin layer chromatography convulsant screen extended by gas chromatography-mass spectrometry.

Acute onset convulsive disorders in the canine may result from exposure to a variety of toxicants including strychnine, insecticides, metaldehyde, zinc phosphide, methylxanthines, drugs of abuse, bromethalin, and the tremorgenic mycotoxins (roquefortine and penitrem A). Although several of the above can be identified in a single gas chromatography-mass spectrometry (GC-MS) screen most have to be determined by separate tests. This report describes a modification of the strychnine extraction procedure, which allows thin layer chromatographic (TLC) identification of strychnine, bromethalin, roquefortine, and penitrem A in suspect baits, stomach contents or vomitus, and extends the identification to a wide variety of drugs, pesticides, and environmental contaminants by GC-MS. Samples were mixed with base, extracted into CH2Cl2 and the organic fraction back-extracted with acid. The organic fraction (neutrals) was purified by gel permeation chromatography (GPC) and analyzed by TLC to determine penitrem A and bromethalin. The acidic aqueous fraction was adjusted to pH > 9 and extracted into CH2Cl2. The resulting CH2Cl2 layer (bases) was then analyzed by TLC to determine strychnine and roquefortine. The organic basic and neutral fractions were recombined with a late eluting GPC fraction and analyzed by GC-MS. Of 312 samples analyzed by TLC from 1995 to 2001, 35 were positive for strychnine alone, 58 were positive for both roquefortine and penitrem A, 4 were positive for roquefortine alone, and 1 was positive for bromethalin. None of the samples were positive for penitrem A alone. Samples negative by TLC were analyzed by the GC-MS extended procedure since mid-1999, and 14 have shown positive for a wide variety of compounds with convulsant activity.

Subacute systemic 3-nitropropionic acid intoxication induces a distinct motor disorder in adult C57Bl/6 mice: behavioural and histopathological characterisation.

Data on motor behavioural disorders induced by systemic 3-nitropropionic acid, an irreversible inhibitor of mitochondrial succinate dehydrogenase and their histopathological correlates in mice, are sparse. We thus further characterised the subacute 3-nitropropionic-acid-induced motor disorder and its time course in C57Bl/6 mice using standard behavioural tests, histopathological correlates and in vivo magnetic resonance imaging. Firstly, we studied two intoxication paradigms (340 and 560 mg 3-nitropropionic acid/kg, 7 days) compared to controls. The low-dose regimen induced only slight motor changes (reduced hindlimb stride length and rearing). The high-dose regimen induced significant (P<0.05) behavioural and sensorimotor integration deficits (pole test, rotarod, stride length, open-field spontaneous activity) but with 37.5% lethality at week one. The clinical motor disorder consisted of hindlimb clasping and dystonia, truncal dystonia, bradykinesia and impaired postural control. Histopathologically, there were discrete lesions of the dorsolateral striatum in 62.5% of mice together with a 32% reduction (P<0.0001) of the striatal volume, reduced caldbindin-D28K immunoreactivity in the lateral striatum, and met-enkephalin and substance P in the striatal output pathways. There was also a significant (P<0.05) 30-40% dopaminergic cell loss within the substantia nigra pars compacta. Secondly, we validated a semi-quantitative behavioural scale to describe the time course of the motor deficits and to predict the occurrence of striatal damage. We sought to determine whether it could also be disclosed in vivo by magnetic resonance imaging. The scale correlated with the striatal volume reduction (r(2)=0.57) and striatal cell loss (r(2)=0.87) but not with the loss of striatal dopaminergic terminals (dopamine transporter binding). Increased T2-signal intensity within the striatal lesion correlated with the cell loss (r(2)=0.66). We conclude that systemic administration of 3-nitropropionic acid in C57Bl/6 mice induces a distinct motor disorder and dose-dependent striatonigral damage, which are potentially useful to model human diseases of the basal ganglia.

Atypical time course of clinical signs in a dog poisoned by strychnine.

The general health of a German shepherd dog had deteriorated slightly when it was found after being loose for one hour. After 10 hours of observation, the dog showed signs of pain for the first time and signs of poisoning, such as tenseness of muscles, slight opisthotonus, regurgitation, salivation, mydriasis, dyspnoea and cyanosis, were observed; it died 15 minutes after showing the first clinical signs but it had no seizures or tetanic spasms at any time. A postmortem examination did not reveal any pathological changes. A screening test for alkaloids was positive for strychnine (strychnidin-10-one). The presence of strychnine was confirmed and its concentration was determined by gas chromatography/mass spectrometry in urine (728.5 ng/ml) and in the stomach contents (44.6m microg/g). No strychnine was detected in the dog's serum, but traces of brucine (2,3-dimethoxystrychnidin-10-one), the dimethoxy derivative of strychnine, were detected. This case was compared with other strychnine poisonings recorded in the authors' laboratory over the previous six years, taking into account the species, type of samples, the clinical signs and their duration, the postmortem findings, and the concentrations of strychnine. This was the only case to show such an atypical time course of clinical signs.

Incidence of intentional poisoning of dogs in the Abruzzo region of Italy.

Toxicological assays done between 1997 and 2000 on 105 presumed baits of the baits and poisonings in 408 dogs are reported. Of the baits, 54.4% were positive for organophosphates and 27.5% for strychnine. In 31.1% of the dog cases, analysis confirmed the presence of toxic concentrations of organophosphate pesticides (43.3%) and strychnine (44.1%).

Analytical detection and quantitation of strychnine in chemically fixed organ tissues.

This study reports the results of the detection and quantitation of strychnine in formalin-fixed tissues and in the formalin solutions in which the tissues were fixed. The toxicological analyses were performed on formalin-fixed liver and kidney samples and formalin solutions (10% buffered pH 7) in which the same samples from a case of acute strychnine poisoning were preserved. The analyses carried out at the time of autopsy on body fluid and tissues (bile, 2.40 mg/L; stomach contents, 14.2 mg; liver, 6.68 mg/kg; kidney, 2.68 mg/kg) allowed the identification of this substance as cause of death. The tissue samples were preserved in formalin solutions for 8 weeks. The analyses performed on formalin-fixed tissues (liver and kidney) and on formalin solutions, in which the same tissues were preserved, permitted the detection and quantitation of strychnine (liver, 1.59 mg/kg; formalin from the liver, 1.80 mg/L; kidney, 0.98 mg/kg; formalin from the kidney, 1.11 mg/L). The results indicate that this particular toxic substance also shows good stability in biological specimens subjected to chemical fixation.

Descompensaçäo cardíaca pós-intoxicaçäo exógena por estricnina: relato de caso / Cardiac descompensation from exogenous intoxication by strychnine: case report

Apresentamos o caso de um paciente intoxicado por estricnina que evoluiu com Insuficiência Cardíaca Congestiva diagnosticada através de ecocardiograma e parâmetros hemodinâmicos conseguidos através de cateter de Swan-Ganz. A intoxicaçao por estricnina nao é comumente encontrada devido à proibiçao de sua comercializaçao, especial atençao tem sido dada a esta droga devido ao seu uso na manufatura de drogas como a cocaína. Alguns autores mostram que a estricnina age sobre centros vasomotores alterando pressao arterial durante as convulsoes, outros mostraram arritmias durante as convulsoes, mas nao comprovaram a existência de cardiotoxidade pela estricnina. A monitorizaçao hemodinâmica foi de bastante auxílio neste caso nao só no sentido de guiar a terapêutica mas também no diagnóstico diferencial do edema pulmonar que, em se tratando de paciente hígido e jovem poderia facilmente ser rotulado como edema "nao cardiogênico". Embora a intoxicaçao por estricnina seja de altíssima mortalidade, com o suporte hemodinâmico e respiratório adequado proporcionamos uma recuperaçao total do paciente, sem seqüela neurológica, renal e pulmonar.

Electrocorticographic changes during generalized convulsive status epilepticus in soman intoxicated rats.

Generalized convulsive status epilepticus (GCSE) is the most common and potentially most damaging form of status epilepticus (SE). It has been previously reported, in both human GCSE and animal models of GCSE, that the electroencephalographs (EEGs) and electrocorticographs (ECoGs) recorded during GCSE contain an ordered sequence of five identifiable patterns: discrete seizures (phase 1), waxing and waning ictal discharges (phase 2), continuous ictal discharges (phase 3), continuous activity with flat periods (phase 4), and periodic epileptiform discharge on a flat background (phase 5). In this paper, we report the same pattern of ECoG changes in 15 rats exposed to soman, an acetylcholinesterase (AChE) inhibitor. Phase 1 was observed in 12 of 15 animals, but phases 2-5 were recorded in all the animals. Taken together, these findings suggest that the sequence of EEG changes is independent of the initiating cause, represent a common electrical response to GCSE, and reflect a common underlying neurochemical mechanism.

[Relation of time of administration of drugs to their acute toxicity to experimental animals].

The circadian rhythms of acute toxicity of N-methyl D-aspartic acid, picrotoxin, pentetrazol, strychnine, chlorpromazine and Na-methylhexabital in dd-mice were investigated. The drugs were injected into mice on the hour at 2, 6, 10, 14, 18 or 22 in one day, after which the cumulative mortalities were calculated for 72 hours. Regarding central stimulants, the mortality of mice injected at 22 (o'clock) was lowest, and when injections were given at 2, 10 or 18 (o'clock), the mortality was higher than at any other time. On the other hand, regarding central depressants, the mortality was lowest at 10, and highest at 14 or at 18 o'clock. Thus, the administration time of central stimulants showing the lowest mortality was shifted about 12 hours in comparison with central depressants. As compared to the central depressants, the mortality rate as the result of central stimulants showed a great contrast when injected at 10 o'clock.