The increased international concern about the threat of military and terroristic use of nerve agents, prompted us to critically consider the expected value of the currently available oxime treatment of nerve agent poisoning. Although oximes have been designed to reactivate the inhibited acetylcholinesterase (AChE), clinical experience has indicated that they are not always very effective as reactivators and at this very moment none of them can be regarded as a broad-spectrum antidote. In spite of this drawback, oximes are worth further investigating, since recent data derived from soman or tabun lethally intoxicated non-human primates suggest that the oxime HI-6 may exert a pharmacological effect that is not related to reactivation of inhibited AChE, but still leads to survival. This pharmacological effect causes recovery of neuronal transmission in the respiratory centres of the brain and recovery of neuromuscular transmission in the diaphragm. These findings have stimulated research to reveal the pharmacological basis of these effects in order to find drugs which could be more effective and less toxic than the available oximes. Since cholinergic drugs were able to exert this effect, a new concept for further treatment is suggested: maintenance of neuronal transmission in spite of continued AChE-inhibition by pharmacological manipulation of the cholinergic receptor. This should renew interest in the diverse pharmacological effects of oximes to reach a more effective treatment in the future.

No abstract

Novichok (NV) nerve agents were recently added to the list of Schedule 1 chemicals of the Chemical Weapons Convention. There is a well-accepted method for assessment of nerve agent exposure based on mass spectrometric analysis of a nonapeptide with the serine-198 residue modified by the nerve agent, but this approach has not yet been reported for the class of NV agents and requires the availability of reference standards, which may be a limitation for NV agent exposure assessment. Thus, a goal of this study was to first verify the utility of the nonapeptide method for the characterization of human plasma samples exposed in vitro to the NV agents A-230, A-232, and A-234. A second aim was to evaluate the possibility of identifying unknown exposures by applying precursor ion scanning in combination with high resolution mass spectrometry (HRMS). Thus, precursor ion scanning, with a generic fragment ion (m/z 778) of the nonapeptide, was used to pinpoint any modified nonapeptide, while HRMS was used for structural elucidation of the adduct moiety. By this approach, use of HRMS enabled differentiation between adducts of agents with similar molecular masses. A new unique feature that could be exploited for NV nonapeptide analysis was that the modification was released from the peptide during fragmentation in the mass spectrometer and was detected in the low-mass region of the mass spectrum. This low-mass region was extremely informative and contributed to the assignment of the structure of the particular agent used, which is especially important in case no reference materials are available. The presented method is important for verification purposes by the Organisation for Prohibition of Chemical Weapons (OPCW), e.g., in case of investigations of alleged use of NV agents, and for regular forensic investigations.

No abstract

Fluorescence-based diagnostic tools are attractive and versatile tests with multiple advantages: ease of use, sensitivity and rapid results. The advent of CRISPR-Cas technology has created new avenues for the development of diagnostic testing tools. In the current study, by effectively combining the specific functions of two enzymes, CRISPR-Cas12a and terminal-deoxynucleotidyl-transferase (TdT), we developed a DNA detection assay that generates copper nanoparticles that are easily visible to the naked eye under UV-light; we named this detection assay CANTRIP: Cas12a Activated Nuclease poly-T Reporter Illuminating Particles. Upon specific target DNA recognition by Cas12a, single-stranded DNA (ssDNA) reporter oligos with blocked 3’-ends are cut into smaller ssDNA fragments, thereby generating neo 3’-OH moieties. TdT subsequently elongates these newly formed ssDNA fragments, incorporating only dTTP nucleotides, and these poly(thymine)-tails subsequently function as scaffolds for the formation of copper nanoparticles (CuNPs). These CuNPs produce a bright fluorescent signal upon UV excitation, and thus, this bright orange signal indicates the presence of target DNA, which in this proof-of-concept study consisted of anthrax lethal factor plasmid DNA. CANTRIP, which combines two detection platforms consisting of CRISPR-Cas12a and fluorescent copper-nanoparticles into a single reaction, appears to be a robust, low-cost and simple diagnostic tool.