Prophylaxis with human serum butyrylcholinesterase protects Göttingen minipigs exposed to a lethal high-dose of sarin vapor.

Serum-derived human butyrylcholinesterase (Hu BChE) is a stoichiometric bioscavenger that is being developed as a potential prophylactic nerve agent countermeasure. Previously, we reported the prophylactic efficacy of Hu BChE in Göttingen minipigs against a whole-body exposure to 4.1mg/m(3) of sarin (GB) vapor, which produced lethality over 60min.

Comparison of sarin and cyclosarin toxicity by subcutaneous, intravenous and inhalation exposure in Gottingen minipigs.

Sexually mature male and female Gottingen minipigs were exposed to various concentrations of GB and GF vapor via whole-body inhalation exposures or to liquid GB or GF via intravenous or subcutaneous injections. Vapor inhalation exposures were for 10, 60 or 180 min. Maximum likelihood estimation was used to calculate the median effect levels for severe effects (ECT50 and ED50) and lethality (LCT50 and LD50).

Pretreatment with human serum butyrylcholinesterase alone prevents cardiac abnormalities, seizures, and death in Göttingen minipigs exposed to sarin vapor.

Human serum butyrylcholinesterase (Hu BChE) is a stoichiometric bioscavenger that is being developed as a prophylactic countermeasure against organophosphorus nerve agents. This study was designed to evaluate the efficacy of Hu BChE against whole-body inhalation exposure to a lethal dose of sarin (GB) vapor. Male Göttingen minipigs were subjected to: air exposure, GB vapor exposure, or pretreatment with Hu BChE followed by GB vapor exposure.

Efficacy of human serum butyrylcholinesterase against sarin vapor.

Human serum butyrylcholinesterase (Hu BChE) is currently under advanced development as a pretreatment drug for organophosphate (OP) poisoning in humans. It was shown to protect mice, rats, guinea pigs, and monkeys against multiple LD(50) challenges of OP nerve agents by i.v.

Quantification of sarin and cyclosarin metabolites isopropyl methylphosphonic acid and cyclohexyl methylphosphonic acid in minipig plasma using isotope-dilution and liquid chromatography- time-of-flight mass spectrometry.

An analysis method for determining isopropyl methylphosphonic acid (IMPA) and cyclohexyl methylphosphonic acid (CMPA), the metabolic hydrolysis products of toxic organophosphorus nerve agents isopropyl methylphosphonofluoridate (sarin, GB) and cyclohexyl methylphosphonofluoridate (cyclosarin, GF), respectively, has been developed and validated using high-performance liquid chromatography-mass spectrometry with negative ion electrospray ionization with time-of-flight detection (LC-ESI-MS-TOF). The linear range of quantitation was 5 to 125 ng/mL in plasma with a method detection limit of 2 ng/mL for each compound. This method was developed to determine the amount of metabolic hydrolysis that was formed during and after nerve agent exposure in minipigs to account for a major pathway of GB and GF elimination that had not been previously characterized in the bloodstream, particularly during low-level whole-body inhalation experiments.

A rapid and sensitive technique for assessing exposure to VX via GC-MS-MS analysis.

A rapid and sensitive method for the determination of the chemical warfare agent VX in plasma taken from Göttingen minipigs has been developed using isotope-dilution gas chromatography-tandem mass spectrometry (GC-MS-MS). Chromatographic separation was achieved on a 5% diphenyl/95% dimethyl polysiloxane capillary column with a total run time of about 11 min. The analyte was detected using ammonia chemical ionization in the multiple reaction monitoring mode, following a simple extraction with 10% 2-propanol in hexane.

Gas chromatography-tandem mass spectrometry analysis of red blood cells from Göttingen minipig following whole-body vapor exposure to VX.

A method to detect fluoride ion generated O-ethyl methylphosphonofluoridate (VX-G) in Göttingen minipig red blood cells (RBC) following whole-body exposure to VX vapor utilizing a gas chromatograph-tandem mass spectrometer (GC-MS-MS) has been developed. Dose-response curves for VX exposure were generated after applying the fluoride ion reactivation assay to the RBC fraction of serially collected whole blood samples that were taken after whole-body exposures that varied in both duration and concentration. GC-MS-MS analysis of minipig RBC samples following 180-min exposures at two different concentrations was a more precise indicator for severity of exposure than the analysis of acetylcholinesterase (AChE) inhibition for the same samples.

The effects of repeated low-dose sarin exposure.

This project assessed the effects of repeated low-dose exposure of guinea pigs to the organophosphorus nerve agent sarin. Animals were injected once a day, 5 days per week (Monday-Friday), for 2 weeks with fractions (0.3x, 0.

Comparison of low-level sarin and cyclosarin vapor exposure on pupil size of the Gottingen minipig: effects of exposure concentration and duration.

The current studies estimated effective (miosis) concentrations of the nerve agents' sarin (GB) and cyclosarin (GF) as a function of exposure duration in the Gottingen minipig and determined dependency of the median effective dosage (ECT50) over time. Male and female Gottingen minipigs were exposed to various concentrations of vapor GB or GF for 10, 60, or 180 min. Infrared images of the pig's pupil before, during, and after nerve agent exposure were captured digitally and pupil area was quantified.

Tolerance to the miotic effect of sarin vapor in rats after multiple low-level exposures.

Inhibition of acetylcholinesterase (AChE) by the organophosphorous compound sarin (GB) results in the accumulation of acetylcholine and excessive cholinergic stimulation. There are few data in the literature regarding the effects of multiple low-level exposures to GB and other organophosphorous compounds via relevant routes of exposure. Therefore, the present study was undertaken, and is the first, to investigate the effect of low-level repeated whole-body inhalation exposures to GB vapor on pupil size and cholinesterase activity in the eyes and blood.

Quantitation of fluoride ion released sarin in red blood cell samples by gas chromatography-chemical ionization mass spectrometry using isotope dilution and large-volume injection.

A new method for measuring fluoride ion released isopropyl methylphosphonofluoridate (sarin, GB) in the red blood cell fraction was developed that utilizes an autoinjector, a large-volume injector port (LVI), positive ion ammonia chemical ionization detection in the SIM mode, and a deuterated stable isotope internal standard. This method was applied to red blood cell (RBC) and plasma ethyl acetate extracts from spiked human and animal whole blood samples and from whole blood of minipigs, guinea pigs, and rats exposed by whole-body sarin inhalation. Evidence of nerve agent exposure was detected in plasma and red blood cells at low levels of exposure.

Ferritin binding in the developing mouse brain follows a pattern similar to myelination and is unaffected by the jimpy mutation.

We have previously provided evidence that ferritin binds selectively to white matter tracts in adult mouse and human brains. In cell culture experiments, ferritin binding is specifically localized to oligodendrocytes. The goal of the present study is to test the hypothesis that the developmental pattern for ferritin binding will coincide with the onset and progression of myelination.

The dose-response effects of repeated subacute sarin exposure on guinea pigs.

The present study assessed the effects of repeated subacute exposure to the organophosphorous nerve agent, sarin. Guinea pigs were injected five times per week (Monday-Friday) for 2 weeks with fractions of the established LD(50) dose of sarin (42 microg/kg sc). The animals were assessed for the development of cortical EEG seizures.

Oligodendrocyte progenitor cells internalize ferritin via clathrin-dependent receptor mediated endocytosis.

We previously demonstrated ferritin binding is specific to white matter in mouse and human brain tissue and is not found within Multiple Sclerotic plaques. These results suggest that ferritin receptors are selectively expressed on oligodendrocytes. The present studies were designed to test the hypothesis that oligodendrocyte progenitor cells selectively bind ferritin and internalize it by methods consistent with receptor-mediated endocytosis.

Distribution of transferrin and ferritin binding in normal and multiple sclerotic human brains.

Delivery of iron to the brain traditionally has been considered the responsibility of transferrin. However, transferrin receptors in brain are located primarily within gray matter areas rather than in the iron rich white matter tracts. In this report we present the first demonstration of ferritin binding sites in human brain and provide evidence that these binding sites are primarily in white matter tracts.

Receptor for interleukin 13 is a marker and therapeutic target for human high-grade gliomas.

Glioblastoma multiforme (GBM) is an incurable brain tumor. Due to the striking heterogeneity that characterizes GBM, there is no known tumor-specific antigen or receptor that is expressed by a majority of GBM patients. We found that virtually all studied human GBM specimens (23 samples) abundantly expressed a receptor for interleukin (IL)-13 in situ, whereas normal human brain had few, if any, IL-13-binding sites.

Characterization and distribution of ferritin binding sites in the adult mouse brain.

Studies on iron uptake into the brain have traditionally focused on transport by transferrin. However, transferrin receptors are not found in all brain regions and are especially low in white matter tracts where high iron concentrations have been reported. Several lines of research suggest that a receptor for ferritin, the intracellular storage protein for iron, may exist.