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    Wyświetlanie 1-5 z 5
    Tytuł:
    DNA double-strand break rejoining in radioadapted human lymphocytes: evaluation by neutral comet assay and pulse-field gel electrophoresis
    Autorzy:
    Wojewódzka, M.
    Buraczewska, I.
    Szumiel, I.
    Grądzka, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/146153.pdf
    Data publikacji:
    2006
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    human lymphocytes
    radioadaptation
    DNA double-strand break rejoining
    neutral comet assay
    pulsefield gel electrophoresis
    Opis:
    Adaptive response (AR), an enhanced resistance to a high dose of ionising radiation acquired after pretreatment with a very low dose, was estimated in normal human lymphocytes. The question posed was whether the extent of radioadaptation, assessed by micronucleus test, would be related to the rate of DNA double-strand break (DSB) rejoining. Phytohemagglutinin-stimulated G1-lymphocytes from 5 healthy male volunteers were pre-treated (or not) with an adaptive (5 cGy) dose of X-rays, followed by a higher (5 or 10 Gy) challenge dose after 20-22 h. DSB rejoining after the challenge dose was monitored with the use of two methods: neutral comet assay, modified to reduce the contribution of single-strand breaks (SSBs) and thermolabile sites, and pulse-field gel electrophoresis (PFGE), specific for DSBs. At the level of micronuclei, an AR was observed in lymphocytes of 3 of 5 donors. Up to 60 min, comet assay showed no statistically significant differences in DNA break rejoining between adapted and non-adapted lymphocytes, independently of AR appearance. PFGE gave similar results, although in three donors it revealed secondary increases in DSBs levels at 30 min and/or 60 min post-irradiation in the adapted vs. the non-adapted samples. Failure to demonstrate changes in DSBs rejoining rate in the adapted lymphocytes could be due to diversity of AR intensity/timing at the level of DNA repair in not fully homogenous cell populations. Also, “rare” DNA cuts characteristic of early apoptosis/necrosis could overlap the process of DNA break rejoining.
    Źródło:
    Nukleonika; 2006, 51, 4; 185-191
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Concerted control of DNA double strand break repair and cell cycle progression in X-irradiated mammalian cells
    Autorzy:
    Sochanowicz, B.
    Szumiel, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/148697.pdf
    Data publikacji:
    2005
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    ATM kinase
    DNA double strand break repair
    RAD50
    cell cycle arrest
    repair foci
    BRCT domain
    Opis:
    Upon examination of cell cycle regulation in a damaged cell, relations were discovered of the cell cycle control mechanisms with a complicated web of signalling pathways, eventually called the genome surveillance system. After infliction of DNA double strand breaks (DSB), the signalling is initiated by sensor proteins and transducer protein kinase ATM. This kinase phosphorylates downstream effector proteins, such as checkpoint kinases CHK1 and CHK2, which initiate the pathways leading to cell cycle arrest. In contrast with the older model of linear transmission of signals in a certain sequence, it is now accepted that the damage signalling system is branched and contains feedback loops. DSB's presence is signalled by sensor proteins (MRE11-RAD50-nibrin complex, MRN) to ATM and the signal is amplified through adaptor proteins, MDC1/NFBD1 or 53BP1 (Tp53 binding protein). MRN contains a forkheadassociated (FHA) domain and BRCA1 carboxyl-terminal (BRCT) domain. The combination of the FHA/BRCT domains has a crucial role for the binding of nibrin to the H2AX histone, assembling the components of repair foci. These domains also are important for interaction of other proteins localised in the foci. For example, MDC1/NFBD1 contains a FHA domain and two BRCT domains which are involved in protein interactions. The signal generated at DSBs is amplified and transduced to recruit components of DNA repair systems. In a concerted way with the sequential recruitment of components of repair foci, activation of transcription of genes takes place, that is necessary for blocking progression through the cell cycle, for DNA repair or apoptosis.
    Źródło:
    Nukleonika; 2005, 50, 4; 129-138
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The PSA analysis of PWR emergency coolant injection availability following SBLOCA
    Autorzy:
    Borysiewicz, M.
    Bronowska, K.
    Kopka, P.
    Kowal, K.
    Kwiatkowski, T.
    Prusiński, A. M.
    Prusiński, P. A.
    Siess, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/146189.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    probabilistic safety assessment (PSA)
    small break LOCA (SBLOCA)
    emergency coolant injection (ECI)
    high pressure injection system (HPIS)
    auxiliary feedwater system (AFWS)
    Opis:
    The aim of this article is to briefly introduce the probabilistic safety assessment (PSA) of nuclear power plants (NPPs), its scope, main concepts and application to a real case. The results of analysis presented here have been obtained by the Probabilistic Safety Analysis Group (GPSA) at the National Centre for Nuclear Research (NCBJ, Otwock) as a part of the work done for the Polish National Atomic Energy Agency (NAEA). As a reference, NPP Surry Unit 1 (USA), equipped with 800 MWe Westinghouse triple-loop PWR (pressurized water reactor), has been chosen. The emergency coolant injection (ECI) function availability following the small break loss of coolant accident (SBLOCA) was thoroughly analyzed. The approach and data, which were adopted for the selected part of the SBLOCA sequences, were those used in the U.S. NRC Reactor Safety Study (WASH-1400). As a result of this study, the SBLOCA event tree, including ECI systems, i.e. high pressure injection system (HPIS) and auxiliary feedwater system (AFWS) reliability models, was developed and quantified. The probability of each accident sequence was evaluated using Saphire v.8, the PSA software by U.S. NRC. The choice of the software was based on earlier PSA software study. The failure probability of at least one of the considered safety systems – P(FAIL) is equal to 5.76E-3 and the most pessimistic accident branch (unavailability of both HPIS and AFWS) is about 0.05% of P(FAIL). These results were obtained based on assumption that the SBLOCA has occured. The most significant failure components are those corresponding to charging pumps unavailability, loss of electric power and human errors.
    Źródło:
    Nukleonika; 2013, 58, 2; 307-316
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Treatment with silver nanoparticles delays repair of X-ray induced DNA damage in HepG2 cells
    Autorzy:
    Wojewódzka, M.
    Lankoff, A.
    Dusińska, M.
    Brunborg, G.
    Czerwińska, J.
    Iwaneńko, T.
    Stępkowski, T.
    Szumiel, I.
    Kruszewski, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/147061.pdf
    Data publikacji:
    2011
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    silver nanoparticles (Ag NP)
    titanium dioxide nanoparticles (TiO2 NP)
    DNA break rejoining
    alkaline comet assay
    ionizing radiation
    combined treatment with nanoparticles + X-rays
    Opis:
    Nanoparticles (NPs) defined as particles having at least one dimension below 100 nm have been applied in the last decade in industry and medicine. Recently, there is an increased concern about the biohazard aspect of the presence of NP in consumer goods and in the environment. Silver NP (Ag NP) cause oxidative stress in mammalian cells in result of generation of reactive oxygen species (ROS). This results in genotoxicity and mutagenicity, disturbed mitochondrial respiration, slowed proliferation and cell death. Using the alkaline comet assay, we examined the effect of combined treatment with Ag NP 20 nm or 200 nm and X-rays (2 Gy) in HepG2 cells. In addition, combined treatment with X-rays and titanium dioxide NP (TiO2 NP) 21 nm was also studied. No effect of NP pre-treatment on X-ray induced initial deoxyribonucleic acid (DNA) damage levels was observed for all three NP. In contrast, Ag NP treatment preceding exposure to X-rays caused a marked decrease in the rate of single strand break rejoining. The effect was particularly strong for Ag NP 20 nm. TiO2 NP pre-treatment had no effect on DNA repair.
    Źródło:
    Nukleonika; 2011, 56, 1; 29-33
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Relationships between EGFR-initiated signalling, DNA double-strand break rejoining and survival in X-irradiated human glioma M059 cells
    Autorzy:
    Grądzka, I.
    Buraczewska, I.
    Szumiel, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/146764.pdf
    Data publikacji:
    2008
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    human glioma M059 K and J cells
    DNA-dependent protein kinase (DNA-PK)
    radiosensitivity
    DNA double-strand break (DSB) rejoining
    epidermal-growth-factor-receptor (EGFR)
    signalling inhibitors: tyrphostin
    Opis:
    The aim of this study was to investigate the effect of signalling inhibition on survival and double-strand break (DSB) rejoining in cells differing in sensitivity to inhibitors, X-rays and bleomycin. Human glioma M059 cells, K (relatively radioresistant) and J (radiosensitive, defective in DSB rejoining for lack of DNA-dependent protein kinase catalytic subunit, DNA-PKcs) were pretreated with signalling inhibitors: tyrphostin AG 1478, specific for epidermalgrowth- factor-receptor (EGFR) kinase or PD 98059, specific for kinase MEK 1/2 (mitogen-activated, extracellular signal-activated kinases 1 and 2). Subsequently, the cells were X-irradiated or treated with bleomycin. Cell survival was determined by clonogenicity test. DSB rejoining was monitored with the use of pulsed-field gel electrophoresis (PFGE). We found that in X-irradiated M059 K cells EGFR kinase activity was necessary for efficient DSB rejoining and the kinase inhibitor, tyrphostin AG 1478, acted as radiosensitizer in the dose range that reduced cell survival to 0.7-0.8. Inhibition of EGFR kinase, however, did not decrease survival or affect DSB rejoining in DNA-PKcs-deficient M059 J cells. These results indicated that the decrease in cell survival was due to a disturbed DSB rejoining by the DNA-PK dependent system. In contrast, inhibition of MEK 1/2 kinase on EGFR downstream signalling pathway by PD 98059 did not affect DSB rejoining in either cell line and exerted a radioprotective effect.
    Źródło:
    Nukleonika; 2008, 53, 2; 37-44
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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