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Search Results: 1 - 10 of 127 matches for " Ewelina Michta "
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Superoxide dismutase is upregulated in Staphylococcus aureus following protoporphyrin-mediated photodynamic inactivation and does not directly influence the response to photodynamic treatment
Joanna Nakonieczna, Ewelina Michta, Magda Rybicka, Mariusz Grinholc, Anna Gwizdek-Wi?niewska, Krzysztof P Bielawski
BMC Microbiology , 2010, DOI: 10.1186/1471-2180-10-323
Abstract: The effectiveness of photodynamic inactivation towards S. aureus and its Sod isogenic mutants deprived of either of the two superoxide dismutase activities, namely SodA or SodM or both of them showed similar results, regardless of the Sod status in TSB medium. On the contrary, in the CL medium (without Mn++ ions) the double SodAM mutant was highly susceptible to photodynamic inactivation. Among 8 clinical isolates of S. aureus analyzed (4 MRSA and 4 MSSA), strains highly resistant and strains highly vulnerable to photodynamic inactivation were noticed. We observed that Sod activity as well as sodA and sodM transcript level increases after protoporphyrin IX-based photodynamic treatment but only in PDI-sensitive strains.We confirmed that porphyrin-based photokilling efficacy is a strain-dependent phenomenon. We showed that oxidative stress sensitivity caused by the lack of both Sod enzymes can be relieved in the presence of Mn ions and partially in the presence of Fe ions. The fact that Sod activity increase is observed only in PDI-susceptible cells emphasizes that this is probably not a direct factor affecting S. aureus vulnerability to porphyrin-based PDI.Staphylococcus aureus, a major human pathogen causes a wide range of disease syndromes, including life-threatening endocarditis, meningitidis and pneumonia. According to the Centers for Disease Control and Prevention this bacterium has been reported to be the most significant cause of serious infections in the United States [1]. S. aureus is able to cause and develop an infection very efficiently due to its ability to produce a few dozen of virulence factors, on one hand, and an ease of antibiotic resistance development, on the other. The most dangerous are methicillin-resistant S. aureus (MRSA) strains, constituting 50% of hospital-aquired isolates as well as emerging vancomycin-resistant variants, isolated from some hospital settings [2].Among several virulence factors, S. aureus produces enzymes responsible for
Proteomic Approach to Reveal the Regulatory Function of Aconitase AcnA in Oxidative Stress Response in the Antibiotic Producer Streptomyces viridochromogenes Tü494
Ewelina Michta, Wei Ding, Shaochun Zhu, Kai Blin, Hongqiang Ruan, Rui Wang, Wolfgang Wohlleben, Yvonne Mast
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0087905
Abstract: The aconitase AcnA from the phosphinothricin tripeptide producing strain Streptomyces viridochromogenes Tü494 is a bifunctional protein: under iron-sufficiency conditions AcnA functions as an enzyme of the tricarboxylic acid cycle, whereas under iron depletion it is a regulator of iron metabolism and oxidative stress response. As a member of the family of iron regulatory proteins (IRP), AcnA binds to characteristic iron responsive element (IRE) binding motifs and post-transcriptionally controls the expression of respective target genes. A S. viridochromogenes aconitase mutant (MacnA) has previously been shown to be highly sensitive to oxidative stress. In the present paper, we performed a comparative proteomic approach with the S. viridochromogenes wild-type and the MacnA mutant strain under oxidative stress conditions to identify proteins that are under control of the AcnA-mediated regulation. We identified up to 90 differentially expressed proteins in both strains. In silico analysis of the corresponding gene sequences revealed the presence of IRE motifs on some of the respective target mRNAs. From this proteome study we have in vivo evidences for a direct AcnA-mediated regulation upon oxidative stress.
On weak solutions of random differential inclusions
Mariusz Michta
International Journal of Stochastic Analysis , 1995, DOI: 10.1155/s1048953395000359
Abstract: In the paper we study the existence of solutions of the random differential inclusion x˙t∈G(t,xt) P.1,t∈[0,T]-a.e.x0=dμ, where G is a given set-valued mapping value in the space Kn of all nonempty, compact and convex subsets of the space n, and μ is some probability measure on the Borel σ-algebra in n. Under certain restrictions imposed on F and μ, we obtain weak solutions of problem (I), where the initial condition requires that the solution of (I) has a given distribution at time t=0.
Continuity properties of solutions of multivalued equations with white noise perturbation
Mariusz Michta
International Journal of Stochastic Analysis , 1997, DOI: 10.1155/s1048953397000300
Abstract: In the paper, we consider a set-valued stochastic equation with stochastic perturbation in a Banach space. We prove first the existence theorem and then study continuity properties of solutions.
Mechanical Properties of Cement Mortar Containing Fine-Grained Fraction of Fly Ashes  [PDF]
Ewelina Tkaczewska
Open Journal of Civil Engineering (OJCE) , 2013, DOI: 10.4236/ojce.2013.32A007

This paper presents the effect of fly ash grain-size fractions on Portland-fly ash cement hydration and its properties. Siliceous fly ashes of size fraction of 0 - 16 and 16 - 32 μm, separated from initial fly ash samples from 1st, 2nd and 3rd hopper in ESP system, were analysed. Cement hydration was investigated by determination of hydration heat and content of Ca(OH)2 and C3S in cement samples. Water to cement ratio and initial setting time of cement pastes as well as compressive strength and microstructure of cement mortars were also analyzed. Results showed that the same amount of the same size ash fraction can give cement of lower or higher early strength and its lower or higher increase with time. Incorporation of 20 wt% of ash fraction of 0 - 16 μm can produce Portland-fly ash cement CEM II/A-V of strength class 42.5R (from 2nd hopper) or 52.5N (from 3rd hopper). Cement containing 40 wt% of ash fraction of 0 - 16 μm from 2nd and 3rd hopper can be classified as pozzolanic cements CEM IV/A-V of strength class 42.5 and normal or rapid early strength, respectively. Different development of strength of cement with addition of the same size ash fraction separated from the initial ash sample from the next hopper in ESP system is connected with higher depolymerization degree of SiO4 units in ash glass, resulting from the greater amount of AlO4 units replacing SiO4 units. Ash fraction of 16 - 32 μm shows lower depolymerisation of glass network and as a consequence lower hydration degree of C3S to portlandite and calcium silicate hydrates (C-S-H).

Ewelina Siwek
Studia Humanistyczne AGH , 2012,
Ewelina Zarzycka
e-Finanse , 2012,
Abstract: The systems have revolutionized practically all aspects of business processes in enterprises. They improve the processes by ensuring their integration. Data are entered into an ERP system only once and immediately afterwards they can be accessed through any of its modules, which makes them a valuable source of information on the enterprise. Integrating the financial and non-financial data, an ERP package gives new quality to the management of enterprise value. These features make ERPs particularly useful for management accounting processes and for specialists providing management information. This article seeks to answer whether following the implementation of an ERP package the enterprise’s management accounting system becomes more innovative and whether new, modern management accounting tools and methods are introduced. The ERP impacts on management accounting and its practices will be evaluated using six case studies involving enterprises owned by multinational corporations.
Comparison of devices supporting safe handling of cytotoxic drugs
Ewelina Korczowska
European Journal of Oncology Pharmacy , 2009,
Abstract: This article cannot decide for you, but provides information to help you make up your own mind when buying cytotoxic handling devices. The questions to answer are: Is it simple? Does it make work safer? Is it affordable?
The DVCS Measurement at HERA
Ewelina Lobodzinska
Physics , 2001, DOI: 10.1088/0954-3899/28/5/331
Abstract: The recent results of the studies of Deeply Virtual Compton Scattering (DVCS) events at HERA are presented. The possibility offered by this process to gain information about skewed parton distributions (SPD) is emphasized.
Mixtures: sequential stability of variational entropy solutions
Ewelina Zatorska
Mathematics , 2013,
Abstract: The purpose of this work is to analyze the mathematical model governing motion of $n$-component, heat conducting reactive mixture of compressible gases. We prove sequential stability of weak variational entropy solutions when the state equation essentially depends on the species concentration and the species diffusion fluxes depend on gradients of partial pressures. Of crucial importance for our analysis is the fact that viscosity coefficients vanish on vacuum and the source terms enjoy the admissibility condition dictated by the second law of thermodynamics.
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