Wyniki wyszukiwania - BazTech

Ograniczanie wyników

3 Nukleonika

Znaleziono wyników: 3

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Treatment with silver nanoparticles delays repair of X-ray induced DNA damage in HepG2 cells

Wojewódzka M., Lankoff A., Dusińska M., Brunborg G., Czerwińska J., Iwaneńko T., Stępkowski T., Szumiel I., Kruszewski M.

Nukleonika

2011

Vol. 56, No. 1

29-33

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.

DNA damage in subpopulations of human lymphocytes irradiated with doses in the range of 0-1 Gy of X-radiation

Wojewódzka M., Machaj E. K., Goździk A., Iwaneńko T., Ołdak T., Kruszewski M., Pojda Z.

Nukleonika

2008

Vol. 53, No. 4

145-149

We compared three methods usually applied in biological dosimetry for estimation of radiation-induced DNA damage in human T and B lymphocytes: alkaline comet assay, micronucleus (MN) test and formation of histone gamma-H2AX foci. Human peripheral blood lymphocytes were fractionated using T cells and B cells isolation kits. Cells were irradiated with doses in the range of 0-1 Gy of X-rays. Induction of DNA damage was assessed by the standard alkaline comet assay, MN test and histone gammaH2AX foci immunofluorescence assay. Notwithstanding different end-points measured by the applied methods, all tests revealed a similar induction of DNA damage in B lymphocytes as compared with T lymphocytes. The results indicated that all three tests detect DNA damage with similar sensitivity, the lowest dose being approximately 0.3 Gy. The difference between irradiated and control cells was expressed as the ratio of the value obtained for irradiated cells (1 Gy) to that for control cells. The highest ratio was obtained for formation of gammaH2AX foci and was 6.2 for T and 13.8 for B lymphocytes, whereas those for comet assay and micronucleus test were 3.5; 3.6 and 5.6; 4.8, respectively.

Application of the DNA comet assay for detection of irradiated meat

Kruszewski M., Malec-Czechowska K., Dancewicz A. M., Iwaneńko T., Szot Z., Wojewódzka M.

Nukleonika

1998

Vol. 43, nr 2

147-160

Radiation induces damage to the DNA. This damage (fragmentation) can be assessed in the irradiated food using Single Cell Gel Electrophoresis (SCGE), known as DNA comet assay. Fragmentation of DNA may also be caused by improper storage of meat and repeated freezing and thawing. This makes identification of irradiated meat by this assay not reliable enough. In order to know the scale of the processes imitating irradiation effects in DNA of the comets, their shape and lenghts were examined in both unirradiated and irradiated fresh meat (D = 1.5 or 3.0 kGy) stored at 4°C or frozen (-21°) up to 5 months. Comets formed upon SCGE were stained with DAPI or silver and examined in fluorescent or light microscope. They were divided arbitrarily into 4 classes. Comets of class IV were found quite often in fresh meat stored at 4°C. In meat samples that were irradiated and stored frozen, comets of class, I, II and III were observed. The negative comet test is univocal. Positive comet test, however, needs confirmation. The meat should be subjected to further analysis with other validated methods.

Promieniowanie powoduje uszkodzenia DNA. Te uszkodzenia (fragmentację) można ocenić w napromieniowanej żywności stosując elektroforezę w żelu pojedynczej komórki, zwaną także testem kometowym. Fragmentację DNA w mięsie mogą także wywoływać: nieprawidłowe przechowywanie mięsa oraz powtarzane zamrażanie i rozmnażanie. Czyni to identyfikację napromieniowania mięsa mniej wiarygodną. W celu poznania procesów imitujących napromieniowanie, tj. powodujących powstawanie kometek DNA, oceniano ich kształt i długość w mięsie nie napromieniowanym i napromieniowanym dawką 1.5 lub 3.0 kGy przechowywanym w 40C lub w stanie zamrożenia do 5 miesięcy. Otrzymane kometki DNA barwiono barwnikiem fluorescencyjnym DAPI lub srebrem i badano w mikroskopie fluorescencyjnym lub zwykłym. Kometki podzielono na 4 klasy. Kometki IV klasy znajdowano często w mięsie przechowywanym w 40C. W próbkach mięsa napromieniowanego i przechowywanego w stanie zamrożenia obserwowano kometki klasy l, II i III. Negatywny test kometowy jest jednoznaczny. Test dodatni wymaga potwierdzenia przez zastosowanie innych metod dających miarodajne wyniki.