Bioscavenger is effective as a delayed therapeutic intervention following percutaneous VX poisoning in the guinea-pig.

The prolonged systemic exposure that follows skin contamination with low volatility nerve agents, such as VX, requires treatment to be given over a long time due to the relatively short half-lives of the therapeutic compounds used. Bioscavengers, such as butyrylcholinesterase (BChE), have been shown to provide effective post-exposure protection against percutaneous nerve agent when given immediately on signs of poisoning and to reduce reliance on additional treatments. In order to assess the benefits of administration of bioscavenger at later times, its effectiveness was assessed when administration was delayed for 2h after the appearance of signs of poisoning in guinea-pigs challenged with VX (4×LD50). VX-challenged animals received atropine, HI-6 and avizafone on signs of poisoning and 2h later the same combination with or without bioscavenger. Five out of 6 animals which received BChE 2h after the appearance of signs of poisoning survived to the end of the study at 48h, compared with 6 out of 6 which received BChE immediately on signs. All the animals (n=6+6) that received only MedCM, without the addition of BChE, died within 10h of poisoning. The toxicokinetics of a sub-lethal challenge of percutaneous VX were determined in untreated animals. Blood VX concentration peaked at approximately 4h after percutaneous dosing with 0.4×LD50; VX was still detectable at 36h and had declined to levels below the lower limit of quantification (10pg/mL) by 48h in 7 of 8 animals, with the remaining animal having a concentration of 12pg/mL. These studies confirm the persistent systemic exposure to nerve agent following percutaneous poisoning and demonstrate that bioscavenger can be an effective component of treatment even if its administration is delayed.

Exposure-response effects of inhaled sulfur mustard in a large porcine model: a 6-h study.

CONTEXT: Inhalation of sulfur mustard (HD) vapor can cause life-threatening lung injury for which there is no specific treatment. A reproducible, characterized in vivo model is required to investigate novel therapies targeting HD-induced lung injury. MATERIALS AND METHODS: Anesthetized, spontaneously breathing large white pigs (~50 kg) were exposed directly to the lung to HD vapor at 60, 100, or 150 µg/kg, or to air, for ~10 min, and monitored for 6 h. Cardiovascular and respiratory parameters were recorded. Blood and bronchoalveolar lavage fluid (BALF) were collected to allow blood gas analysis, hematology, and to assay for lung inflammatory cells and mediators. Urine was collected and analyzed for HD metabolites. Histopathology samples were taken postmortem (PM). RESULTS: Air-exposed animals maintained normal lung physiology whilst lying supine and spontaneously breathing. There was a statistically significant increase in shunt fraction across all three HD-exposed groups when compared with air controls at 3-6 h post-exposure. Animals were increasingly hypoxemic with respiratory acidosis. The monosulfoxide ß-lyase metabolite of HD (1-methylsulfinyl-2-[2(methylthio)ethylsulfonyl)ethane], MSMTESE), was detected in urine from 2 h post-exposure. Pathological examination revealed necrosis and erosion of the tracheal epithelium in medium and high HD-exposed groups. CONCLUSION: These findings are consistent with those seen in the early stages of acute lung injury (ALI).

Early treatment with nebulised salbutamol worsens physiological measures and does not improve survival following phosgene induced acute lung injury.

OBJECTIVES: To examine the effectiveness of nebulised salbutamol in the treatment of phosgene induced acute lung injury. METHOD: Using previously validated methods, 12 anaesthetised large white pigs were exposed to phosgene (Ct 1978 +/- 8 mg min m(-3)), established on mechanical ventilation and randomised to treatment with either nebulised salbutamol (2.5 mg per dose) or saline control. Treatments were given 1, 5, 9, 13, 17 and 21 hours following phosgene exposure. The animals were followed to 24 hours following phosgene exposure. RESULTS: Salbutamol treatment had no effect on mortality and had a deleterious effect on arterial oxygenation, shunt fraction and heart rate. There was a reduction in the number of neutrophils from 24.0% +/- 4.4 to 12.17% +/- 2.1 (p < 0.05) in bronchoalveolar lavage, with some small decreases in inflammatory mediators in bronchoalveolar lavage but not in plasma. CONCLUSION: Nebulised salbutamol treatment following phosgene induced acute lung injury does not improve survival, and worsens various physiological parameters including arterial oxygen partial pressure and shunt fraction. Salbutamol treatment reduces neutrophil influx into the lung. Its sole use following phosgene exposure is not recommended.

Preliminary studies of sulphur mustard-induced lung injury in the terminally anesthetized pig: exposure system and methodology.

ABSTRACT Although normally regarded as a vesicant, inhalation of sulphur mustard (HD) vapor can cause life-threatening lung injury for which there is no specific treatment. Novel therapies for HD-induced lung injury are best investigated in an in vivo model that allows monitoring of a range of physiological variables. HD vapor was generated using two customized thermostatically controlled glass flasks in parallel. The vapor was passed into a carrier flow of air (81 L. min(-1)) and down a length of glass exposure tube (1.75 m). A pig was connected to the midpoint of the exposure tube via a polytetrafluoroethylene-lined endotracheal tube, Fleisch pneumotachograph, and sample port. HD vapor concentrations (40-122.8 mg. m(-3)) up-and downstream of the point of exposure were obtained by sampling onto Porapak absorption tubes with subsequent analysis by gas chromatography-flame photometric detection. Real-time estimates of vapor concentration were determined using a photo-ionization detector. Lung function indices (respiratory volumes, lung compliance, and airway resistance) were measured online throughout. Trial runs with methylsalicylate (MS) and animal exposures with HD demonstrated that the exposure system rapidly reached the desired concentration within 1 min and maintained stable output throughout exposure, and that the MS/HD concentration decayed rapidly to zero when switched off. A system is described that allows reproducible exposure of HD vapor to the lung of anesthetized white pigs. The system has proved to be robust and reliable and will be a valuable tool in assessing potential future therapies against HD-induced lung injury in the pig. Crown Copyright (c) 2007 Dstl.

Multiple vaccine and pyridostigmine interactions: effects on EEG and sleep in the common marmoset.

Following active service during the 1990/1991 Gulf conflict, a number of UK and US veterans presented with a diverse range of symptoms, collectively known as Gulf Veterans' Illnesses (GVI). The administration of vaccines and/or the pretreatment against possible nerve agent poisoning, pyridostigmine bromide (PB), given to Armed Forces personnel during the Gulf conflict has been implicated as a possible factor in the aetiology of these illnesses. The possibility that long-term health effects may result from the administration of these vaccines (anthrax, pertussis, plague, yellow fever, polio, typhoid, tetanus, hepatitis B, meningococcal meningitis and cholera) and/or PB, have been investigated using a non-human primate model, the common marmoset. This paper reports the results from two aspects of the study, brain electrical activity (EEG, collected during performance of a touchscreen mediated discrimination task) and sleep. There were no marked long-term changes in EEG or sleep patterns that could be attributed to vaccines and/or PB administration. The changes that were detected were predominantly time related and independent of treatment. Where statistical differences were detected between treatments, the magnitudes of the difference were relatively minor and therefore not regarded as having long term biological significance.

A novel method for activity monitoring in small non-human primates.

Patterns of spontaneous activity are valuable reflections of well-being in animals and humans and, because of this, investigations have frequently incorporated some form of activity monitoring into their studies. It is widely believed that activity monitoring, alongside assessments of general behaviour, should be included in initial CNS safety pharmacology screening. As the number of marmoset studies having actimetry as their focus, or as an adjunct, is increasing, we wished to evaluate an alternative approach to those commonly used. The method is based on miniaturized accelerometer technologies, currently used for human activity monitoring.Actiwatch-Minis were used to monitor the activity of two groups of differently housed marmosets for 14 consecutive days. Group A consisted of four mixed-sex pairs of animals and group B comprised eight group-housed males. Activity profiles were generated for weekday and weekend periods. The devices captured quantifiable data which showed differences in total activity between the two differently housed groups and revealed intragroup variations in the temporal spread of activity between weekdays and weekends. The Actiwatch-Mini has been shown to generate retrospective, data-logged activity counts recorded from multiple animals in a single arena by means of non-invasive monitoring.

Food deprivation during different periods of tadpole (Hyla chrysoscelis) ontogeny affects metamorphic performance differently.

Tadpoles in small, ephemeral pools whose duration and food content are unpredictable can potentially encounter substantial variation in diet composition and availability. We compared the effects of 10 days of food deprivation occurring early, midway and late in ontogeny on the metamorphic size and bioenergetic properties of Hyla chrysoscelis tadpoles. Tadpoles fed throughout ontogeny were controls. Metamorphs from tadpoles starved early and midway in ontogeny had the same snout-vent length and dry mass as controls, but the time to metamorphosis was extended by 8 and 19% respectively. Metamorphs of tadpoles starved late in development attained 85% of the length and 55% of the mass of controls, metamorphosed at the same time as controls, and suffered mortality 15 times greater than other treatments, perhaps because they were near the absolute minimum necessary level of energy reserves. There were no significant differences in percent organic matter, percent tissue water, condition index, and protein or glycogen concentrations between any experimental and control treatments. If food deprivation occurred early in development, the tadpoles caught up to the size of controls, but an extended developmental time would increase the risk of predation or habitat loss. If food reductions occur late in development, perhaps magnified by pond desiccation, tadpoles are stimulated to metamorphose at the same time as controls but at a smaller size. The bioenergetic composition of tadpoles at metamorphosis is unaffected by time of food deprivation.

Nigericin-induced death of an acidophilic bacterium.

At an external pH of 3.5, nigericin (which catalyses an electroneutral H+/K+ exchange) abolished the transmembrane proton gradient (delta pH) of Bacillus acidocaldarius, causing a rapid acidification of the cytoplasm from approximately pH 6.0 to pH 3.5. A pronounced loss of viability and fine-structural changes rapidly followed treatment with nigericin. A marked decline in respiration and an even more rapid decrease in cytoplasmic ATP were observed. Activity of at least one cytoplasmic enzyme decreased more slowly. There was no generalized loss in the integrity of the cytoplasmic membrane, as assayed by permeability to inulin or Na+ or by release of ultraviolet light-absorbing compounds. The loss of viability upon treatment with carbonyl cyanide m-chlorophenylhydrazone was similar to what observed with nigericin, so proton influx alone, rather than together with K+ efflux, was probably involved in the death of the organism. Moreover, acidification of the cytoplasm rather than abolition of the delta pH was the lethal event, since no loss of viability was observed when the delta pH was abolished by elevation of the external pH.