98 research outputs found
The physiological concentration of ferrous iron (II) alters the inhibitory effect of hydrogen peroxide on CD45, LAR and PTP1B phosphatases
Hydrogen peroxide is an important regulator of protein tyrosine phosphatase activity via reversible oxidation. However, the role of iron in this reaction has not been yet elucidated. Here we compare the influence of hydrogen peroxide and the ferrous iron (reagent for Fenton reaction) on the enzymatic activity of recombinant CD45, LAR, PTP1B phosphatases and cellular CD45 in Jurkat cells. The obtained results show that ferrous iron (II) is potent inhibitor of CD45, LAR and PTP1B, but the inhibitory effect is concentration dependent. We found that the higher concentrations of ferrous iron (II) increase the inactivation of CD45, LAR and PTP1B phosphatase caused by hydrogen peroxide, but the addition of the physiological concentration (500 nM) of ferrous iron (II) has even a slightly preventive effect on the phosphatase activity against hydrogen peroxide
Antimicrobials Are a Photodynamic Inactivation Adjuvant for the Eradication of Extensively Drug-Resistant Acinetobacter baumannii
The worldwide emergence of extensively drug resistant (XDR) Acinetobacter baumannii has reduced the number of antimicrobials that exert high bactericidal activity against this pathogen. This is the reason why many scientists are focusing on investigations concerning novel non-antibiotic strategies such as antimicrobial photodynamic inactivation (aPDI) or the use of antimicrobial blue light (aBL). Therefore, the aim of the current study was to screen for antimicrobial synergies of routinely used antibiotics and phototherapies, including both aPDI involving exogenously administered photosensitizing molecules, namely, rose bengal, and aBL, involving excitation of endogenously produced photoactive compounds. The synergy testing was performed in accordance with antimicrobial susceptibility testing (AST) standards, including various methodological approaches, i.e., antibiotic diffusion tests, checkerboard assays, CFU counting and the evaluation of postantibiotic effects (PAEs). We report that combining antimicrobials and aPDI/aBL treatment led to a new strategy that overcomes drug resistance in XDR A. baumannii, rendering this pathogen susceptible to various categories of antibiotics. Sublethal aPDI/aBL treatment in the presence of sub-MIC levels of antimicrobials effectively killed A. baumannii expressing drug resistance to studied antibiotics when treated with only antibiotic therapy. The susceptibility of XDR A. baumannii to a range of antibiotics was enhanced following sublethal aPDI/aBL. Furthermore, 3′-(p-aminophenyl) fluorescein (APF) testing indicated that significantly increased reactive oxygen species production upon combined treatment could explain the observed synergistic activity. This result represents a conclusive example of the synergistic activity between photodynamic inactivation and clinically used antimicrobials leading to effective eradication of XDR A. baumannii isolates and indicates a potent novel therapeutic approach
2D FEM Calculation of AC Losses in Twisted Superconductors with a Helicoidal Transformation
We propose a Helicoidal Transformation for 2D Finite Element Method (FEM) calculation of AC losses in twisted conductors. The method is based on a helicoidal change of variables to transform the originally 3D problem into an equivalent 2D problem. For obtaining the critical state in superconductor we use the h-φ-formulation and E-J power law. The method is well suited for geometries with a helicoidal symmetry and we present the magnetic response and Joule losses of multifilamentary twisted wire in conducting matrix and CORC cable with a non-conducting core
Electromagnetically assisted densification of copper-sheathed in situ MgB2/Cu wires
peer-reviewedThis paper summarizes recent methods of
improving critical current density of in situ Cu-sheathed
MgB2 wires. These methods include using optimum heat
treatment schedule, adding copper powder to the wire core
and electromagnetic densification of wire core. The large
part of work reported here focuses on the latter method
applied to the relatively low-density MgB2/Cu wire core.
The packing density of unreacted, monofilament wire core
was increased by 8 % with oscillating magnetic pressure,
reaching a peak value above 700 MPa as calculated by
finite element modelling of the forming process. The higher
density of the MgB2 core combined with copper powder
addition resulted in a critical current density increase of
more than fivefold in comparison to purely stoichiometric
and cold-drawn-only wire.PUBLISHEDpeer-reviewe
Towards a muon collider
A muon collider would enable the big jump ahead in energy reach that is needed for a fruitful exploration of fundamental interactions. The challenges of producing muon collisions at high luminosity and 10 TeV centre of mass energy are being investigated by the recently-formed International Muon Collider Collaboration. This Review summarises the status and the recent advances on muon colliders design, physics and detector studies. The aim is to provide a global perspective of the field and to outline directions for future work
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