Quantum Dots Do Not Affect the Behaviour of Mouse Embryonic Stem Cells and Kidney Stem Cells and Are Suitable for Short-Term Tracking

Quantum dots (QDs) are small nanocrystals widely used for labelling cells in order to enable cell tracking in complex environments in vitro, ex vivo and in vivo. They present many advantages over traditional fluorescent markers as they are resistant to photobleaching and have narrow emission spectra. Although QDs have been used effectively in cell tracking applications, their suitability has been questioned by reports showing they can affect stem cell behaviour and can be transferred to neighbouring cells. Using a variety of cellular and molecular biology techniques, we have investigated the effect of QDs on the proliferation and differentiation potential of two stem cell types: mouse embryonic stem cells and tissue-specific stem cells derived from mouse kidney. We have also tested if QDs released from living or dead cells can be taken up by neighbouring cells, and we have determined if QDs affect the degree of cell-cell fusion; this information is critical in order to assess the suitability of QDs for stem cell tracking. We show here that QDs have no effect on the viability, proliferation or differentiation potential of the two stem cell types. Furthermore, we show that the extent of transfer of QDs to neighbouring cells is <4%, and that QDs do not increase the degree of cell-cell fusion. However, although the QDs have a high labelling efficiency (>85%), they are rapidly depleted from both stem cell populations. Taken together, our results suggest that QDs are effective cell labelling probes that are suitable for short-term stem cell tracking

Genomic investigations of unexplained acute hepatitis in children

Since its first identification in Scotland, over 1,000 cases of unexplained paediatric hepatitis in children have been reported worldwide, including 278 cases in the UK1. Here we report an investigation of 38 cases, 66 age-matched immunocompetent controls and 21 immunocompromised comparator participants, using a combination of genomic, transcriptomic, proteomic and immunohistochemical methods. We detected high levels of adeno-associated virus 2 (AAV2) DNA in the liver, blood, plasma or stool from 27 of 28 cases. We found low levels of adenovirus (HAdV) and human herpesvirus 6B (HHV-6B) in 23 of 31 and 16 of 23, respectively, of the cases tested. By contrast, AAV2 was infrequently detected and at low titre in the blood or the liver from control children with HAdV, even when profoundly immunosuppressed. AAV2, HAdV and HHV-6 phylogeny excluded the emergence of novel strains in cases. Histological analyses of explanted livers showed enrichment for T cells and B lineage cells. Proteomic comparison of liver tissue from cases and healthy controls identified increased expression of HLA class 2, immunoglobulin variable regions and complement proteins. HAdV and AAV2 proteins were not detected in the livers. Instead, we identified AAV2 DNA complexes reflecting both HAdV-mediated and HHV-6B-mediated replication. We hypothesize that high levels of abnormal AAV2 replication products aided by HAdV and, in severe cases, HHV-6B may have triggered immune-mediated hepatic disease in genetically and immunologically predisposed children

L'ergonomie: entre science, technologie et realite

National audienceL'ergonomie, telle qu'elle est analysee ici par un specialiste danois, est concue comme art de l'ingenieur. La presentation de l'aval des resultats concrets fournis par l'ergonomie permet de mettre en evidence les rapports entre ceux-ci et les choix faits par l'entrepreneur en matiere de confort et de sante du collectif de travail. Differentes applications de l'ergonomie illustrent le propos : applications militaires, applications civiles pour les biens de consommation (appareils menagers, automobiles) et pour l'industrie (poste de travail). L'auteur se demande pourquoi et comment l'ergonomie, en tant qu'outil d'amelioration de la situation de travail, est souvent detournee par les responsables de l'entreprise

L'ergonomie: entre science, technologie et realite

National audienceL'ergonomie, telle qu'elle est analysee ici par un specialiste danois, est concue comme art de l'ingenieur. La presentation de l'aval des resultats concrets fournis par l'ergonomie permet de mettre en evidence les rapports entre ceux-ci et les choix faits par l'entrepreneur en matiere de confort et de sante du collectif de travail. Differentes applications de l'ergonomie illustrent le propos : applications militaires, applications civiles pour les biens de consommation (appareils menagers, automobiles) et pour l'industrie (poste de travail). L'auteur se demande pourquoi et comment l'ergonomie, en tant qu'outil d'amelioration de la situation de travail, est souvent detournee par les responsables de l'entreprise

Phonon dispersion in silicon nanocrystals

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