These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: [Mechanisms of radioresistance in terminally differentiated cells of mature retina].
    Author: Tronov VA, Vinogradova IuV, Loginova MIu, Poplinskaia VA, Ostrovskiĭ MA.
    Journal: Tsitologiia; 2012; 54(3):261-9. PubMed ID: 22645991.
    Abstract:
    Retinopathy of animals is induced by many agents damaging DNA. This fact shows that DNA lesions may initiate retinal degeneration. The aim of our work was to study the effects of gamma and proton irradiation, and methylnitrosourea (MNU) on mice retina. We evaluated morphological changes, DNA damage and repair in retina, and expression of 5 proteins participating in apoptosis: p53, ATM, FasR, PARP and caspase 3 active. Dose of 14 Gy is equitoxic in terms of induction of DNA single strand breaks by both gamma and proton irradiation. But protons were 2 fold more effective than gamma-rays in induction of DNA double strand breaks. All breaks were repaired within < or =10 h. Irradiation resulted in increased expression of p53 and ATM. But no sings of cell death and retinal degeneration were observed during 7 days after irradiation. Proton irradiation in dose of 25 Gy resulted in increasing over time destructive changes localized mainly in photoreceptor layer of retina. These changes were followed by increased expression of proapoptotic proteins. A single systemic administration of MNU (70 mg/kg) increased intracellular levels of p53, PARP, FasR, caspase 3 active, which was followed by destructive changes in retina with sings of apoptosis of photoreceptors. As in the case of irradiation, the 2-fold dose reduction of MNU abrogated cytotoxic effect of MNU on retina. High level of spontaneous DNA damage such as apurine and apyrimidine sites were observed in mouse retina. The results of our study demonstrate the occurrence of genotoxic threshold in the initiation of retinal cell death in vivo. Topoisomerase 2 of retina is suggested to translate primary DNA damage to cytotoxic effect.
    [Abstract] [Full Text] [Related] [New Search]