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Pleine-Fougères, France

Benestad S.L.,Norwegian Veterinary Institute | Baron T.,Agence Nationale de Securite Sanitaire | Kretzschmar H.,Ludwig Maximilians University of Munich
Topics in Current Chemistry | Year: 2011

Although prion diseases, such as Creutzfeldt-Jakob disease (CJD) in humans and scrapie in sheep, have long been recognized, our understanding of their epidemiology and pathogenesis is still in its early stages. Progress is hampered by the lengthy incubation periods and the lack of effective ways of monitoring and characterizing these agents. Protease-resistant conformers of the prion protein (PrP), known as the "scrapie form" (PrP Sc), are used as disease markers, and for taxonomic purposes, in correlation with clinical, pathological, and genetic data. In humans, prion diseases can arise sporadically (sCJD) or genetically (gCJD and others), caused by mutations in the PrP-gene (PRNP), or as a foodborne infection, with the agent of bovine spongiform encephalopathy (BSE) causing variant CJD (vCJD). Person-to-person spread of human prion disease has only been known to occur following cannibalism (kuru disease in Papua New Guinea) or through medical or surgical treatment (iatrogenic CJD, iCJD). In contrast, scrapie in small ruminants and chronic wasting disease (CWD) in cervids behave as infectious diseases within these species. Recently, however, so-called atypical forms of prion diseases have been discovered in sheep (atypical/Nor98 scrapie) and in cattle, BSE-H and BSE-L. These maladies resemble sporadic or genetic human prion diseases and might be their animal equivalents. This hypothesis also raises the significant public health question of possible epidemiological links between these diseases and their counterparts in humans. © 2011 Springer-Verlag Berlin Heidelberg.

Tarantini A.,Agence Nationale de Securite Sanitaire | Lanceleur R.,Agence Nationale de Securite Sanitaire | Mourot A.,Agence Nationale de Securite Sanitaire | Lavault M.T.,University of Rennes 1 | And 4 more authors.
Toxicology in Vitro | Year: 2015

Silica (SiO2) in its nanosized form is now used in food applications although the potential risks for human health need to be evaluated in further detail. In the current study, the uptake of 15 and 55nm colloidal SiO2 NPs in the human intestinal Caco-2 cell line was investigated by transmission electron microscopy. The ability of these NPs to induce cytotoxicity (XTT viability test), genotoxicity (γH2Ax and micronucleus assay), apoptosis (caspase 3), oxidative stress (oxidation of 2,7-dichlorodihydrofluorescein diacetate probe) and proinflammatory effects (interleukin IL-8 secretion) was evaluated. Quartz DQ12 was used as particle control. XTT and cytokinesis-block micronucleus assays revealed size- and concentration-dependent effects on cell death and chromosome damage following exposure to SiO2 nanoparticles, concomitantly with generation of reactive oxygen species (ROS), SiO2-15nm particles being the most potent. In the same way, an increased IL-8 secretion was only observed with SiO2-15nm at the highest tested dose (32μg/ml). TEM images showed that both NPs were localized within the cytoplasm but did not enter the nucleus. SiO2-15nm, and to a lower extent SiO2-55nm, exerted toxic effects in Caco-2 cells. The observed genotoxic effects of these NPs are likely to be mediated through oxidative stress rather than a direct interaction with the DNA. Altogether, our results indicate that exposure to SiO2 NPs may induce potential adverse effects on the intestinal epithelium in vivo. © 2014 Elsevier Ltd.

Haenni M.,Agence Nationale de Securite Sanitaire | Chatre P.,Agence Nationale de Securite Sanitaire | Madec J.-Y.,Agence Nationale de Securite Sanitaire
Frontiers in Microbiology | Year: 2014

In both humans and animals, the spread of Extended-Spectrum ß-Lactamases (ESBL)/AmpC producers has become a major issue, particularly due to the plasmidic dissemination of most of these genes. Besides, over-expression of the chromosomal ampC gene was largely reported in human and animal Enterobacteriaceae and, more recently, modifications within the coding region of the ampC gene [encoding Extended-spectrum AmpC β-lactamases (ESACs)] were shown to be responsible for an hydrolysis spectrum expanded to oxyiminocephalosporins in humans. In this study, among 6765 cattle E. coli isolates, 28 (0.37%) isolates harboring a reduced susceptibility to cefepime (MICs ranging from 0.5 to 12 μg/ml) were investigated as presumptive ESACs producers. Highly conserved mutations in the promoter/attenuator region were identified at positions -88, -82, -42, -18, -1, and +58. Using sequencing and cloning experiments, amino acid substitutions of the AmpC beta-lactamase were characterized at positions 287 (mostly S287N, but also S287C), 292 (A292V) and 296 (H296P), similarly to data reported in humans. Interestingly, those cattle ESAC-producing E. coli isolates predominantly belonged to the Clonal Complex (CC) 23, thus mirroring what has been described in humans. The driving forces for the selection of ESACs in animals are unknown, and their prevalence needs to be further investigated in the different animal sectors. Considering the over-representation of ESAC-producing E. coli belonging to CC23 in both humans and animals, exchanges of ESAC producers between the two populations may have occurred as well. To our best knowledge, this study is the first report of ESACs in animals worldwide, which should be considered an emerging mechanism contributing to the resistance to extended-spectrum cephalosporins in the animal population. © 2014 Haenni, Châtre and Madec.

Haenni M.,Agence Nationale de Securite Sanitaire | Saras E.,Agence Nationale de Securite Sanitaire | Metayer V.,Agence Nationale de Securite Sanitaire | Medaille C.,Laboratoire dAnalyses Veterinaires | Madec J.-Y.,Agence Nationale de Securite Sanitaire
Antimicrobial Agents and Chemotherapy | Year: 2014

In the community, close contacts between humans and dogs may promote the transfer of extended-spectrum beta-lactamase/ plasmidic AmpC cephalosporinase (ESBL/pAmpC) genes. Large-scale prevalence studies on ESBL/pAmpC carriage in dogs are rare, and data on ESBL/pAmpC plasmids are even more limited. Here, a considerable rate of 18.5% ESBL/pAmpC carriers was found among 368 unrelated healthy dogs in Paris, France. This prevalence is much higher than the one found in healthy humans in the same city (6%) but close to that recently reported in dogs in China (24.5%). All isolates were identified as Escherichia coli, except one Salmonella enterica and one Klebsiella pneumoniae isolate. The sequence type 131 (ST131) clone was rare (2/73 isolates). Interestingly, two plasmids (blaCTX-M-1/IncI1/ST3 and blaCMY-2/IncI1/ST2) were unexpectedly highly predominant, raising the question of their successful spread. Considering that CTX-M-1 was recently found to be equally as abundant as CTX-M-15 in healthy Parisian subjects, the question of dogs being a CTX-M-1 reservoir for humans is open. Such a high prevalence of the bla CMY-2/IncI1/ST2 plasmid may result from the use of cephalexin in veterinary medicine, as previously demonstrated experimentally. In all, our study points out healthy urban dogs as a potential source of ESBL/pAmpC genes that can further disseminate to the human community. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

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