Calas AG


Full name : Calas Andre-Guilhem

First name : Andre-Guilhem

Mail : French Armed Forces Biomedical Research Institute, Toxicology and chemical risks department, Bretigny-sur-Orge\; UMR 8257 - Cognition and Action Group, Paris Descartes University

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Country : France

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References (7)

Title : No-observed-adverse-effect-level (NOAEL) assessment as an optimized dose of cholinesterase reactivators for the treatment of exposure to warfare nerve agents in mice - Trancart_2024_Chem.Biol.Interact__110929
Author(s) : Trancart M , Hanak AS , Dambrune C , Madi M , Voros C , Baati R , Calas AG
Ref : Chemico-Biological Interactions , :110929 , 2024
Abstract : Despite the international convention on the prohibition of chemical weapons ratified in 1997, the threat of conflicts and terrorist attacks involving such weapons still exists. Among these, organophosphorus-nerve agents (OPs) inhibit cholinesterases (ChE) causing cholinergic syndrome. The reactivation of these enzymes is therefore essential to protect the poisoned people. However, these reactivating molecules, mainly named oximes, have major drawbacks with limited efficacy against some OPs and a non-negligible ChE inhibitor potential if administered at an inadequate dose, an effect that they are precisely supposed to mitigate. As a result, this project focused on assessing therapeutic efficacy, in mice, up to the NOAEL dose, the maximum dose of oxime that does not induce any observable toxic effect. NOAEL doses of HI-6 DMS, a reference oxime, and JDS364. HCl, a candidate reactivator, were assessed using dual-chamber plethysmography, with respiratory ventilation impairment as a toxicity criterion. Time-course modeling parameters and pharmacodynamic profiles, reflecting the interaction between the oxime and circulating ChE, were evaluated for treatments at their NOAEL and higher doses. Finally, the therapeutic potential against OPs poisoning was determined through the assessment of protective indices. For JDS364. HCl, the NOAEL dose corresponds to the smallest dose inducing the most significant therapeutic effect without causing any abnormality in ChE activity. In contrast, for HI-6 DMS, its therapeutic benefit was observed at doses higher than its NOAEL, leading to alterations in respiratory function. These alterations could not be directly correlated with ChE inhibition and had no adverse effects on survival. They are potentially attributed to the stimulation of non-enzymatic cholinergic targets by HI-6 DMS. Thus, the NOAEL appears to be an optimal dose for evaluating the efficacy of oximes, particularly when it can be linked to respiratory alterations effectively resulting from ChE inhibition.
ESTHER : Trancart_2024_Chem.Biol.Interact__110929
PubMedSearch : Trancart_2024_Chem.Biol.Interact__110929
PubMedID: 38417730

Title : A New Class of Bi- and Trifunctional Sugar Oximes as Antidotes against Organophosphorus Poisoning - Da Silva_2022_J.Med.Chem_65_4649
Author(s) : Da Silva O , Probst N , Landry C , Hanak AS , Warnault P , Coisne C , Calas AG , Gosselet F , Courageux C , Gastellier AJ , Trancart M , Baati R , Dehouck MP , Jean L , Nachon F , Renard PY , Dias J
Ref : Journal of Medicinal Chemistry , 65 :4649 , 2022
Abstract : Recent events demonstrated that organophosphorus nerve agents are a serious threat for civilian and military populations. The current therapy includes a pyridinium aldoxime reactivator to restore the enzymatic activity of acetylcholinesterase located in the central nervous system and neuro-muscular junctions. One major drawback of these charged acetylcholinesterase reactivators is their poor ability to cross the blood-brain barrier. In this study, we propose to evaluate glucoconjugated oximes devoid of permanent charge as potential central nervous system reactivators. We determined their in vitro reactivation efficacy on inhibited human acetylcholinesterase, the crystal structure of two compounds in complex with the enzyme, their protective index on intoxicated mice, and their pharmacokinetics. We then evaluated their endothelial permeability coefficients with a human in vitro model. This study shed light on the structural restrains of new sugar oximes designed to reach the central nervous system through the glucose transporter located at the blood-brain barrier.
ESTHER : Da Silva_2022_J.Med.Chem_65_4649
PubMedSearch : Da Silva_2022_J.Med.Chem_65_4649
PubMedID: 35255209
Gene_locus related to this paper: human-ACHE

Title : An Antidote Screening System for Organophosphorus Poisoning Using Zebrafish Larvae - Dubrana_2021_ACS.Chem.Neurosci__
Author(s) : Dubrana LE , Knoll-Gellida A , Bourcier LM , Merce T , Pedemay S , Nachon F , Calas AG , Baati R , Soares M , Babin PJ
Ref : ACS Chem Neurosci , : , 2021
Abstract : Organophosphorus (OP) cholinesterase inhibitors, which include insecticides and chemical warfare nerve agents, are very potent neurotoxicants. Given that the actual treatment has several limitations, the present study provides a general method, called the zebrafish-OP-antidote test (ZOAT), and basic scientific data, to identify new antidotes that are more effective than the reference pyridinium oximes after acute OP poisoning. The reactivation capacity of a chemical compound can be measured using in vivo and ex vivo acetylcholinesterase (AChE) assays. We demonstrated that it is possible to differentiate between chemical compound protective efficacies in the central and peripheral nervous system via the visual motor response and electric field pulse motor response tests, respectively. Moreover, the ability to cross the brain-blood barrier can be estimated in a physiological context by combining an AChE assay on the head and trunk-tail fractions and the cellular and tissue localization of AChE activity in the whole-mount animal. ZOAT is an innovative method suitable for the screening and rapid identification of chemicals and mixtures used as antidote for OP poisoning. The method will make it easier to identify more effective medical countermeasures for chemical threat agents, including combinatorial therapies.
ESTHER : Dubrana_2021_ACS.Chem.Neurosci__
PubMedSearch : Dubrana_2021_ACS.Chem.Neurosci__
PubMedID: 34284583

Title : Efficacy Assessment of an Uncharged Reactivator of NOP-Inhibited Acetylcholinesterase Based on Tetrahydroacridine Pyridine-Aldoxime Hybrid in Mouse Compared to Pralidoxime - Calas_2020_Biomolecules_10_
Author(s) : Calas AG , Hanak AS , Jaffre N , Nervo A , Dias J , Rousseau C , Courageux C , Brazzolotto X , Villa P , Obrecht A , Goossens JF , Landry C , Hachani J , Gosselet F , Dehouck MP , Yerri J , Kliachyna M , Baati R , Nachon F
Ref : Biomolecules , 10 : , 2020
Abstract : (1) Background: Human exposure to organophosphorus compounds employed as pesticides or as chemical warfare agents induces deleterious effects due to cholinesterase inhibition. One therapeutic approach is the reactivation of inhibited acetylcholinesterase by oximes. While currently available oximes are unable to reach the central nervous system to reactivate cholinesterases or to display a wide spectrum of action against the variety of organophosphorus compounds, we aim to identify new reactivators without such drawbacks. (2) Methods: This study gathers an exhaustive work to assess in vitro and in vivo efficacy, and toxicity of a hybrid tetrahydroacridine pyridinaldoxime reactivator, KM297, compared to pralidoxime. (3) Results: Blood-brain barrier crossing assay carried out on a human in vitro model established that KM297 has an endothelial permeability coefficient twice that of pralidoxime. It also presents higher cytotoxicity, particularly on bone marrow-derived cells. Its strong cholinesterase inhibition potency seems to be correlated to its low protective efficacy in mice exposed to paraoxon. Ventilatory monitoring of KM297-treated mice by double-chamber plethysmography shows toxic effects at the selected therapeutic dose. This breathing assessment could help define the No Observed Adverse Effect Level (NOAEL) dose of new oximes which would have a maximum therapeutic effect without any toxic side effects.
ESTHER : Calas_2020_Biomolecules_10_
PubMedSearch : Calas_2020_Biomolecules_10_
PubMedID: 32512884

Title : Respiratory failure triggered by cholinesterase inhibitors may involve activation of a reflex sensory pathway by acetylcholine spillover - Nervo_2019_Toxicology_424_152232
Author(s) : Nervo A , Calas AG , Nachon F , Krejci E
Ref : Toxicology , 424 :152232 , 2019
Abstract : Respiration failure during exposure by cholinesterase inhibitors has been widely assumed to be due to inhibition of cholinesterase in the brain. Using a double chamber plethysmograph to measure various respiratory parameters, we observed long "end inspiratory pauses" (EIP) during most exposure that depressed breathing. Surprisingly, Colq KO mice that have a normal level of acetylcholinesterase (AChE) in the brain but a severe deficit in muscles and other peripheral tissues do not pause the breathing by long EIP. In mice, long EIP can be triggered by a nasal irritant. Eucalyptol, an agonist of cold receptor (TRPM8) acting on afferent sensory neurons and known to reduce the EIP triggered by such irritants, strongly reduced the EIP induced by cholinesterase inhibitor. These results suggest that acetylcholine (ACh) spillover from the neuromuscular junction, which is unchanged in Colq KO mice, may activate afferent sensory systems and trigger sensory reflexes, as reversed by eucalyptol. Indeed, the role of AChE at the cholinergic synapses is not only to accurately control the synaptic transmission but also to prevent the spillover of ACh. In the peripheral tissues, the ACh flood induced by cholinesterase inhibition may be very toxic due to interaction with non-neuronal cells that use ACh at low levels to communicate with afferent sensory neurons.
ESTHER : Nervo_2019_Toxicology_424_152232
PubMedSearch : Nervo_2019_Toxicology_424_152232
PubMedID: 31175885

Title : An easy method for the determination of active concentrations of cholinesterase reactivators in blood samples: Application to the efficacy assessment of non quaternary reactivators compared to HI-6 and pralidoxime in VX-poisoned mice - Calas_2017_Chem.Biol.Interact_267_11
Author(s) : Calas AG , Dias J , Rousseau C , Arboleas M , Touvrey-Loiodice M , Mercey G , Jean L , Renard PY , Nachon F
Ref : Chemico-Biological Interactions , 267 :11 , 2017
Abstract : Organophosphorus nerve agents, like VX, are highly toxic due to their strong inhibition potency against acetylcholinesterase (AChE). AChE inhibited by VX can be reactivated using powerful nucleophilic molecules, most commonly oximes, which are one major component of the emergency treatment in case of nerve agent intoxication. We present here a comparative in vivo study on Swiss mice of four reactivators: HI-6, pralidoxime and two uncharged derivatives of 3-hydroxy-2-pyridinaldoxime that should more easily cross the blood-brain barrier and display a significant central nervous system activity. The reactivability kinetic profile of the oximes is established following intraperitoneal injection in healthy mice, using an original and fast enzymatic method based on the reactivation potential of oxime-containing plasma samples. HI-6 displays the highest reactivation potential whatever the conditions, followed by pralidoxime and the two non quaternary reactivators at the dose of 50 mg/kg bw. But these three last reactivators display equivalent reactivation potential at the same dose of 100 mumol/kg bw. Maximal reactivation potential closely correlates to surviving test results of VX intoxicated mice.
ESTHER : Calas_2017_Chem.Biol.Interact_267_11
PubMedSearch : Calas_2017_Chem.Biol.Interact_267_11
PubMedID: 26972668

Title : Characterization of seizures induced by acute exposure to an organophosphate herbicide, glufosinate-ammonium - Calas_2016_Neuroreport_27_532
Author(s) : Calas AG , Perche O , Richard O , Perche A , Paris A , Lauga F , Herzine A , Palomo J , Ardourel MY , Menuet A , Mortaud S , Pichon J , Montecot-Dubourg C
Ref : Neuroreport , 27 :532 , 2016
Abstract : Glufosinate-ammonium (GLA), the active component of a widely used herbicide, induces convulsions in rodents and humans. In mouse, intraperitoneal treatment with 75 mg/kg GLA generates repetitive tonic-clonic seizures associated with 100% mortality within 72 h after treatment. In this context, we characterized GLA-induced seizures, their histological consequences and the effectiveness of diazepam treatment. Epileptic discharges on electroencephalographic recordings appeared simultaneously in the hippocampus and the cerebral cortex. Diazepam treatment at 6 h immediately stopped the seizures and prevented animal death. However, intermittent seizures were recorded on electroencephalogram from 6 h after diazepam treatment until 24 h, but had disappeared after 15 days. In our model, neuronal activation (c-Fos immunohistochemistry) was observed 6 h after GLA exposure in the dentate gyrus, CA1, CA3, amygdala, piriform and entorhinal cortices, indicating the activation of the limbic system. In these structures, Fluoro-Jade C and Cresyl violet staining did not show neuronal suffering. However, astroglial activation was clearly observed at 24 h and 15 days after GLA treatment in the amygdala, piriform and entorhinal cortices by PCR quantitative, western blot and immunohistochemistry. Concomitantly, glutamine synthetase mRNA expression (PCR quantitative), protein expression (western blot) and enzymatic activity were upregulated. In conclusion, our study suggests that GLA-induced seizures: (a) involved limbic structures and (b) induced astrocytosis without neuronal degeneration as an evidence of a reactive astrocyte beneficial effect for neuronal protection.
ESTHER : Calas_2016_Neuroreport_27_532
PubMedSearch : Calas_2016_Neuroreport_27_532
PubMedID: 27031874