Structural and adhesive properties of the long polar fimbriae protein LpfD from adherent-invasive Escherichia coli

Crohn's disease (CD) is an inflammatory bowel disease characterized by an exaggerated immune response to commensal microbiota in the intestines of patients. Metagenomic studies have identified specific bacterial species and strains with increased prevalence in CD patients, amongst which is the adherent-invasive Escherichia coli (AIEC) strain LF82. AIEC strains express long polar fimbriae (LPF), which are known to target Peyer's patches in a mouse CD model. Here, the recombinant production of a soluble, self-complemented construct of the LpfD protein of E. coli LF82 is reported and it is demonstrated that it forms the adhesive tip subunit of LPF. The LpfD crystal reveals an N-terminal adhesin domain and a C-terminal pilin domain that connects the adhesin to the minor pilus subunit LpfE. Surface topology and sequence conservation in the adhesin domain hint at a putative receptor-binding pocket as found in the Klebsiella pneumoniae MrkD and E. coli F17-G (GafD) adhesins. Immunohistostaining of murine intestinal tissue sections revealed that LpfD specifically binds to the intestinal mucosa and submucosa. LpfD binding was found to be resistant to treatment with O- or N-glycosidases, but was lost in collagenase-treated tissue sections, indicating the possible involvement of an intestinal matrix-associated protein as the LpfD receptor. LpfD strongly adhered to isolated fibronectin in an in vitro assay, and showed lower levels of binding to collagen V and laminin and no binding to collagens I, III and IV

Re-emerging infectious diseases from the past: Hysteria or real risk?

International audienceBACKGROUND:Work on human remains and old biological samples is a potential source of contamination by conventional or atypical infectious agents. Similarly, current and future environmental changes are a source of resurgence of ancient epidemic diseases. To what extent are anthropologists sorcerer apprentices (especially those working on ancient samples, i.e. paleo-anthropologists)? Are ancient skeletons, palaeosols and museum objects with a biological component at risk for current populations? Unless there are unfounded fears and undue risk… What can be learned from the recent scientific literature and the common sense of the researchers?METHODS:We have attempted to compile data from the literature and from our personal experience in the fields of anthropology, clinical medicine and epidemiology, in order to grasp the reality of the risk to the human population.RESULTS:It appears that the risk is real, but extremely limited. Specific and simple protective measures must be taken in terms of overall and individual health, both in the field and in the laboratory.CONCLUSION:These data are important for the internist, due to the possibility of atypical infections, both in specialized workers and in populations at risk (environmental context)

Crystallization of the FaeE chaperone of Escherichia coli F4 fimbriae

The periplasmic chaperone FaeE of E. coli F4 fimbriae crystallizes in three crystal forms

Transversalité d'une méthodologie de conception de l'environnement construit basée sur des scènes visuelles et centrée sur l'utilisateur

La problématique du développement durable oblige à revisiter l’ensemble des paramètres de la conception d’environnements construits, dont les facteurs humains. Ainsi que le montrent les enquêtes de qualité, les notions de confort et de bien-être reposent indubitablement sur notre perception de l’environnement construit. Il convient donc de développer des stratégies de conception centrées sur les facteurs humains. La recherche présentée vise à élaborer un outil de conception architecturale, sous la forme ultime d'un logiciel CAAD, favorisant une démarche collaborative et participative. S'appuyant sur le concept de « vision sérielle », l'environnement construit est considéré comme une succession de scènes visuelles organisées en séquences. Afin de définir les principes d'une méthodologie de conception, les interactions entre espaces urbains et la perception des piétons ont été identifiés, comparés, organisés. Cette méthodologie fournit aux concepteurs un outil qui, par la visualisation du projet sous forme de visuels aisément compréhensibles par le plus grand nombre. Ce qui favorise une démarche participative, facteur de cohésion sociale, et une meilleure appropriation de l'environnement construit