Biology subjects

Guillot, J.

Publications and source records attributed to Guillot, J..

4 recordsLinked to original sources

bioRxiv2020

Sympathetic axonal sprouting induces changes in macrophage populations and protects against pancreatic cancer

Recent evidence has highlighted the presence of neuronal nerve processes in the tumor microenvironment. However, the origin of intra-tumoral nerves remains poorly known, in part because of technical difficulties in tracing nerve fibers via regular histological preparations. Here, we employed three-dimensional (3D) imaging of cleared tissues for a comprehensive analysis of sympathetic innervation in pancreatic ductal adenocarcinoma (PDAC). The results support two independent, but coexisting, mechanisms: passive engulfment of pre-existing nerves within tumors and active, localized sprouting of nerve terminals into non-neoplastic lesions and tumor periphery. Nerve ablation revealed an inverse correlation between sympathetic innervation and tumor growth and spread. Furthermore, sympathectomy increased CD163+ macrophage levels, which contributed to worse outcomes. Altogether, our findings revealed protective properties of the sympathetic nervous system in PDAC immunity and progression that could pave the way for new treatments.

cancer biology↗

bioRxiv2019

In vitro activity of beauvericin against all developmental stages of Sarcoptes scabiei

BackgroundScabies is a frequent cutaneous infection caused by the mite Sarcoptes scabiei in a large number of mammals including humans. As the resistance of S. scabiei against several chemical acaricides has been previously documented, the establishment of alternative and effective control molecules is required.\n\nObjectivesIn this study, the potential acaricidal activity of beauvericin was assessed against different life stages of S. scabiei var. suis and, in comparison with dimpylate and ivermectin, two commercially available molecules used for the treatment of S. scabiei infection in animals and/or humans.\n\nMethodsIn our in vitro model, developmental stages of S. scabiei have been placed in Petri dishes filled with Columbia agar supplemented with pig serum and different concentrations of the drugs. Moreover, the toxicity of beauvericin against cultured human fibroblast skin cells was evaluated using an MTT proliferation assay\n\nResultsBeauvericin showed higher activity against adults and eggs of S. scabiei when compared to dimpylate and ivermectin. In addition, cell sensitivity assays demonstrated low toxicity of beauvericin against primary human fibroblast skin cells.\n\nConclusionThese results revealed that the use of beauvericin is promising and might be considered for the treatment of S. scabiei infection.

microbiology↗

bioRxiv2019

Compilation of 29-year postmortem examinations identifies a \"Millennium bug\" in equine parasite communities

Horses are infected by a wide range of parasite species that form complex communities. Parasite control imposes significant constraints on parasite communities whose monitoring remains however difficult to track through time. Postmortem examination is a reliable method to quantify parasite communities. Here, we compiled 1,673 necropsy reports accumulated over 29 years, in the reference necropsy centre from Normandy (France). The burden of non-strongylid species was quantified and the presence of strongylid species was noted. Details of horse deworming history and the cause of death were registered. Building on these data, we investigated the temporal trend in non-strongylids epidemiology and we determined the contribution of parasites to the death of horses throughout the study period. Data analyses revealed the seasonal variations of non-strongylid parasite abundance and reduced worm burden in race horses. Beyond these observations, we found a shift in the species responsible for fatal parasitic infection from the year 2000 onward, whereby fatal cyathostominosis and Parascaris spp. infection have replaced death cases caused by S. vulgaris and tapeworms. Concomitant break in the temporal trend of parasite species prevalence was also found within a 10-year window (1998-2007) that has seen the rise of Parascaris spp. and the decline of both Gasterophilus spp. and tapeworms. A few cases of parasite persistence following deworming were identified that all occurred after 2000. Altogether, these findings provide insights into major shifts in non-strongylid parasite prevalence and abundance over the last 29 years. They also underscore the critical importance of Parascaris spp. in young equids.

zoology↗

bioRxiv2017

Risk factor analysis of equine strongyle resistance to anthelmintics

Intestinal strongyles are the most problematic endoparasites of equids as a result of their wide distribution and the spread of resistant isolates throughout the world. While abundant literature can be found on the extent of anthelmintic resistance across continents, empirical knowledge about associated risk factors is missing. This study brought together results from anthelmintic efficacy testing and risk factor analysis to provide evidence-based guidelines in the field. It involved 688 horses from 39 French horse farms and riding schools to both estimate Faecal Egg Count Reduction (FECR) after anthelmintic treatment and to interview farm and riding school managers about their practices. Risk factors associated with reduced anthelmintic efficacy in equine strongyles were estimated across drugs using a marginal modelling approach. Results demonstrated ivermectin efficacy (96.3% FECR), the inefficacy of fenbendazole (42.8% FECR) and an intermediate profile for pyrantel (90.3% FECR). Risk factor analysis provided support to advocate for FEC-based treatment regimens combined with individual anthelmintic dosage and the enforcement of tighter biosecurity around horse introduction that contributed to lower drug resistance risk by 1.75. Premises falling under this typology also relied more on their veterinarians suggesting they play an important role in the sustainability of anthelmintic usage. Similarly, drug resistance risk was halved in premises with frequent pasture rotation and with stocking rate below five horses/ha. This is the first empirical risk factor analysis for anthelmintic resistance in equids, whose findings should guide the implementation of more sustained strongyle management in the field.

zoology↗