University of Siena

About: University of Siena is a education organization based out in Siena, Italy. It is known for research contribution in the topics: Population & Cancer. The organization has 12179 authors who have published 33334 publications receiving 1008287 citations. The organization is also known as: Università degli studi di Siena & Universita degli studi di Siena.

Bacteria-induced neo-biosynthesis, stabilization, and surface expression of functional class I molecules in mouse dendritic cells

Abstract: Here, we show that bacteria induce de novo synthesis of both major histocompatability complex (MHC) class I and II molecules in a mouse dendritic cell culture system. The neo-biosynthesis of MHC class I molecules is delayed as compared with that of MHC class II. Furthermore, bacteria stabilize MHC class I molecules by a 3-fold increase of their half-life. This has important consequences for the capacity of dendritic cells to present bacterial antigens in the draining lymph nodes. In addition, a model antigen, ovalbumin, expressed on the surface of recombinant Streptococcus gordonii is processed and presented on MHC class I molecules. This presentation is 10(6) times more efficient than that of soluble OVA protein. This exogenous pathway of MHC class I presentation is transporter associated with antigen processing (TAP)-dependent, indicating that there is a transport from phagolysosome to cytosol in dendritic cells. Thus, bacteria are shown to be a potentially useful mean for the correct delivery of exogenous antigens to be presented efficiently on MHC class I molecules.

Guidelines for the good practice of surface wave analysis: a product of the InterPACIFIC project

Abstract: Surface wave methods gained in the past decades a primary role in many seismic projects. Specifically, they are often used to retrieve a 1D shear wave velocity model or to estimate the VS,30 at a site. The complexity of the interpretation process and the variety of possible approaches to surface wave analysis make it very hard to set a fixed standard to assure quality and reliability of the results. The present guidelines provide practical information on the acquisition and analysis of surface wave data by giving some basic principles and specific suggestions related to the most common situations. They are primarily targeted to non-expert users approaching surface wave testing, but can be useful to specialists in the field as a general reference. The guidelines are based on the experience gained within the InterPACIFIC project and on the expertise of the participants in acquisition and analysis of surface wave data.

MgrB Inactivation Is a Common Mechanism of Colistin Resistance in KPC-Producing Klebsiella pneumoniae of Clinical Origin

Abstract: Klebsiella pneumoniae strains producing KPC-type carbapenemases (KPC-KP) are challenging multidrug-resistant pathogens due to their extensively drug-resistant phenotypes and potential for epidemic dissemination in health care settings. Colistin is a key component of the combination antimicrobial regimens used for treatment of severe KPC-KP infections. We previously reported that insertional inactivation of the mgrB gene, encoding a negative-feedback regulator of the PhoQ-PhoP signaling system, can be responsible for colistin resistance in KPC-KP, due to the resulting upregulation of the Pmr lipopolysaccharide modification system. In this work we investigated the status of the mgrB gene in a collection of 66 colistin-resistant nonreplicate clinical strains of KPC-KP isolated from different hospitals in Italy and Greece. Overall, 35 strains (53%) exhibited alterations of the mgrB gene, including insertions of different types of mobile elements (IS5-like, IS1F-like, or ISKpn14), nonsilent point mutations, and small intragenic deletions. Four additional strains had a larger deletion of the mgrB locus, while the remaining 27 strains (41%) did not show mgrB alterations. Transcriptional upregulation of the phoQ and pmrK genes (part of the phoPQ and pmrHFIJKLM operon, respectively) was observed in all strains with mgrB alterations. Complementation experiments with a wild-type mgrB gene restored colistin susceptibility and basal expression levels of phoQ and pmrK genes in strains carrying different types of mgrB alterations. The present results suggest that mgrB alteration can be a common mechanism of colistin resistance among KPC-KP in the clinical setting.

Performance of photon reconstruction and identification with the CMS detector in proton-proton collisions at √s = 8 TeV

Abstract: A description is provided of the performance of the CMS detector for photon reconstruction and identification in proton-proton collisions at a centre-of-mass energy of 8 TeV at the CERN LHC. Details are given on the reconstruction of photons from energy deposits in the electromagnetic calorimeter (ECAL) and the extraction of photon energy estimates. The reconstruction of electron tracks from photons that convert to electrons in the CMS tracker is also described, as is the optimization of the photon energy reconstruction and its accurate modelling in simulation, in the analysis of the Higgs boson decay into two photons. In the barrel section of the ECAL, an energy resolution of about 1% is achieved for unconverted or late-converting photons from H→γγ decays. Different photon identification methods are discussed and their corresponding selection efficiencies in data are compared with those found in simulated events.