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Titolo:
Condensed chromatin and cell inactivation by single-hit kinetics
Autore:
Chapman, JD; Stobbe, CC; Gales, T; Das, IJ; Zellmer, DL; Biade, S; Matsumoto, Y;
Indirizzi:
Fox Chase Canc Ctr, Dept Radiat Oncol, Philadelphia, PA 19111 USA Fox Chase Canc Ctr Philadelphia PA USA 19111 , Philadelphia, PA 19111 USA Fox Chase Canc Ctr, Canc Res Inst, Philadelphia, PA 19111 USA Fox Chase Canc Ctr Philadelphia PA USA 19111 , Philadelphia, PA 19111 USA Mercy Hosp, Dept Med Phys, Scranton, PA 18501 USA Mercy Hosp Scranton PA USA 18501 p, Dept Med Phys, Scranton, PA 18501 USA
Titolo Testata:
RADIATION RESEARCH
fascicolo: 4, volume: 151, anno: 1999,
pagine: 433 - 441
SICI:
0033-7587(199904)151:4<433:CCACIB>2.0.ZU;2-T
Fonte:
ISI
Lingua:
ENG
Soggetto:
CHINESE-HAMSTER CELLS; DOUBLE-STRAND BREAKS; HUMAN-TUMOR-CELLS; IONIZING-RADIATION; MAMMALIAN-CELLS; X-RAYS; INTRINSIC RADIOSENSITIVITY; METAPHASE CHROMOSOME; V(D)J RECOMBINATION; DNA-DAMAGE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
49
Recensione:
Indirizzi per estratti:
Indirizzo: Chapman, JD Fox19111e Canc Ctr, Dept Radiat Oncol, 7701 Burholme Ave, Philadelphia, PA Fox Chase Canc Ctr 7701 Burholme Ave Philadelphia PA USA 19111
Citazione:
J.D. Chapman et al., "Condensed chromatin and cell inactivation by single-hit kinetics", RADIAT RES, 151(4), 1999, pp. 433-441

Abstract

Mammalian cells are extremely sensitive to gamma rays at mitosis, the timeat which their chromatin is maximally condensed, The radiation-induced killing of mitotic cells is well described by single-hit inactivation kinetics. To investigate if radiation hypersensitivity by single-hit inactivation correlated with chromatin condensation, Chinese hamster ovary (CHO) K1 (wildtype) and xrs-5 (radiosensitive mutant) cells were synchronized by mitotic shake-off procedures and the densities of their chromatin cross sections and their radiosensitivities were measured immediately and 2 h into G(1) phase. The chromatin of G(1)-phase CHO K1 cells was dispersed uniformly throughout their nuclei, and its average density was at least three times less than in the chromosomes of mitotic CHO K1 cells. The or-inactivation coefficient of mitotic CHO K1 cells was similar to 2.0 Gy(-1) and decreased similar to 10-fold when cells entered G(1) phase. The density of chromatin in CHO xrs-5 cell chromosomes at mitosis was greater than in CHO K1 cell chromosomes, and the radiosensitivity of mitotic CHO xrs-5 cells was the greatest with alpha = 5.1 Gy(-1). In G(1) phase, CHO xrs-5 cells were slightly more resistant to radiation than when in mitosis, but a significant proportion of their chromatin was found to remain in condensed form adjacent to the nuclear membrane, These studies indicate that in addition to their known defects in DNA repair and V(D)J recombination, CHO xrs-5 cells may also be defective in some process associated with the condensation and/or dispersion of chromatin at mitosis. Their radiation hypersensitivity could result, in part, from their DNA remaining in compacted form during interphase. The condensation status of DNA in other mammalian cells could define their intrinsic radiosensitivity by single-hit inactivation, the mechanism of cell killing which dominates at the dose fraction size (1.8-2.0 Gy) most commonly used in radiotherapy. (C) 1999 by Radiation Research Society.

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Documento generato il 04/07/20 alle ore 04:33:12