Brigitte Arbeille

University of Tours, Tours, Centre, France

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Publications (4)16.85 Total impact

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    ABSTRACT: This work is a follow-up of our previous paper (Heinlaan et al., 2008. Chemosphere 71, 1308-1316) where we showed about 50-fold higher acute toxicity of CuO nanoparticles (NPs) compared to bulk CuO to water flea Daphnia magna. In the current work transmission electron microscopy (TEM) was used to determine potential time-dependent changes in D. magna midgut epithelium ultrastructure upon exposure to CuO NPs compared to bulk CuO at their 48 h EC(50) levels: 4.0 and 175 mg CuO/L, respectively. Special attention was on potential internalization of CuO NPs by midgut epithelial cells. Ingestion of both CuO formulations by daphnids was evident already after 10 min of exposure. In the midgut lumen CuO NPs were dispersed whereas bulk CuO was clumped. By the 48th hour of exposure to CuO NPs (but not to equitoxic concentrations of bulk CuO) the following ultrastructural changes in midgut epithelium of daphnids were observed: protrusion of epithelial cells into the midgut lumen, presence of CuO NPs in circular structures analogous to membrane vesicles from holocrine secretion in the midgut lumen. Implicit internalization of CuO NPs via D. magna midgut epithelial cells was not evident however CuO NPs were no longer contained within the peritrophic membrane but located between the midgut epithelium microvilli. Interestingly, upon exposure to CuO NPs bacterial colonization of the midgut occurred. Ultrastructural changes in the midgut of D. magna upon exposure to CuO NPs but not to bulk CuO refer to its nanosize-related adverse effects. Time-dependent solubilisation of CuO NPs and bulk CuO in the test medium was quantified by recombinant Cu-sensor bacteria: by the 48th hour of exposure to bulk CuO, the concentration of solubilised copper ions was 0.05 ± 0.01 mg Cu/L that was comparable to the acute EC(50) value of Cu-ions to D. magna (48 h CuSO(4) EC(50) = 0.07 ± 0.01 mg Cu/L). However, in case of CuO NPs, the solubilised Cu-ions 0.01 ± 0.001 mg Cu/L, explained only part of the toxicity.
    Water Research 01/2011; 45(1):179-90. DOI:10.1016/j.watres.2010.08.026 · 5.32 Impact Factor
  • Toxicology Letters 07/2010; 196. DOI:10.1016/j.toxlet.2010.03.1165 · 3.36 Impact Factor
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    ABSTRACT: The dura mater has 2 dural layers: the endosteal layer (outer layer), which is firmly attached to the bone, and the meningeal layer (inner layer), which directly covers the brain. These 2 dural layers join together in the middle temporal fossa or the convexity and separate into the orbital, lateral sellar compartment (LSC), or spinal epidural space to form the extradural neural axis compartment (EDNAC). The aim of this work was to anatomically verify the concept of the EDNAC by using electron microscopy. The authors studied the cadaveric heads obtained from 13 adults. Ten of the specimens (or 20 perisellar areas) were injected with colored latex and fixed in formalin. They carefully removed each brain to allow a superior approach to the perisellar area. The 3 other specimens were studied by microscopic and ultrastructural methods to describe the EDNAC in the perisellar area. Special attention was paid to the dural layers surrounding the perisellar area. The authors studied the anatomy of the meningeal architecture of the LSC, the petroclival venous confluence, the orbit, and the trigeminal cave. After dissection, the authors took photographs of the dural layers with the aid of optical magnification. The 3 remaining heads, obtained from fresh cadavers, were prepared for electron microscopic study. The EDNAC is limited by the endosteal layer and the meningeal layer and contains fat and/or venous blood. The endosteal layer and meningeal layer were not identical on electron microscopy; this finding can be readily related to the histology of the meninges. In this study, the authors demonstrated the existence of the EDNAC concept in the perisellar area by using dissected cadaveric heads and verified the reality of the concept of the meningeal layer with electron microscopy. These findings clearly demonstrated the existence of the EDNAC, a notion that has generally been accepted but never demonstrated microscopically.
    Journal of Neurosurgery 02/2010; 113(5):1045-52. DOI:10.3171/2010.1.JNS081701 · 3.15 Impact Factor
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    ABSTRACT: The formation of biofilm results in a major lifestyle switch that is thought to affect the expression of multiple genes and operons. We used DNA arrays to study the global effect of biofilm formation on gene expression in mature Escherichia coli K-12 biofilm. We show that, when biofilm is compared with the exponential growth phase, 1.9% of the genes showed a consistent up- or downregulation by a factor greater than two, and that 10% of the E. coli genome is significantly differentially expressed. The functions of the genes induced in these conditions correspond to stress response as well as energy production, envelope biogenesis and unknown functions. We provide evidence that the expression of stress envelope response genes, such as the psp operon or elements of the cpx and rpoE pathways, is a general feature of E. coli mature biofilms. We also compared biofilm with the stationary growth phase and showed that the biofilm lifestyle, although sharing similarities with the stationary growth phase, triggers the expression of specific sets of genes. Using gene disruption of 54 of the most biofilm-induced genes followed by a detailed phenotypic study, we validated the biological relevance of our analysis and showed that 20 of these genes are required for the formation of mature biofilm. This group includes 11 genes of previously unknown function. These results constitute a comprehensive analysis of the global transcriptional response triggered in mature E. coli biofilms and provide insights into its physiological signature.
    Molecular Microbiology 03/2004; 51(3):659-74. DOI:10.1046/j.1365-2958.2003.03865.x · 5.03 Impact Factor