title: Suitability of scoring PCC rings and fragments for dose assessment after high-dose exposures to ionizing radiation.
abstract: Assessment of radiation doses through measurement of dicentric chromosomes may be difficult due to the inability of damaged cells to reach mitosis. After high-dose exposures, premature chromosome condensation (PCC) has become an important method in biodosimetry. PCC can be induced upon fusion with mitotic cells, or by treatment with chemicals such as calyculin A or okadaic acid. Several different cytogenetic endpoints have been measured with chemically induced PCC, e.g., via scoring of extra chromosome pieces or ring chromosomes. The dose-effect curves published with chemically induced PCC show differences in their coefficients and in the distribution of rings among cells. Here we present a study with calyculin A to induce PCC in peripheral blood lymphocytes irradiated at nine different doses of γ-rays up to 20Gy. Colcemid was also added in order to observe metaphase cells. During microscopical analysis the chromosome aberrations observed in the different cell-cycle phases (G2/M-PCC, M/A-PCC and M cells) were recorded. The proportion of G2/M-PCC cells was predominant from 3 to 20Gy, M cells decreased above 1Gy and M/A-PCC cells remained constant at all doses and showed the highest frequencies of PCC rings. Depending on the cell-cycle phase there was a difference in the linear coefficients in the dose-effect curves of extra fragments and rings. Poisson distribution among PCC rings was observed after calyculin A+colcemid treatment, facilitating the use of this methodology also for partial body exposures to high doses. This has been tested with two simulated partial exposures to 6 and 12Gy. The estimated doses in the irradiated fraction were very close to the real dose, indicating the usefulness of this methodology.
authors.affiliation: Unitat d'Antropologia Biològica, Departament de Biologia Animal, Biologia Vegetal i Ecologia, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain. Electronic address: rpuigcasanovas@gmail.com.
authors.forename: Roser
authors.initials: R
authors.lastname: Puig
authors.forename: Leonardo
authors.initials: L
authors.lastname: Barrios
authors.forename: Mònica
authors.initials: M
authors.lastname: Pujol
authors.forename: Maria Rosa
authors.initials: MR
authors.lastname: Caballín
authors.forename: Joan-Francesc
authors.initials: JF
authors.lastname: Barquinero
mesh_terms: D002478:Cells, Cultured; D002869:Chromosome Aberrations / Q000187:drug effects / Q000528:radiation effects; D002875:Chromosomes / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008214:Lymphocytes / Q000166:cytology / Q000528:radiation effects; D008387:Marine Toxins; D008677:Metaphase / Q000187:drug effects / Q000528:radiation effects; D008938:Mitosis / Q000528:radiation effects*; D010080:Oxazoles / Q000494:pharmacology; D011829:Radiation Dosage; D011839:Radiation, Ionizing; D012303:Ring Chromosomes
chemical_list: D008387:Marine Toxins; D010080:Oxazoles; C059041:calyculin A
keywords: Biological dosimetry; Chromosome aberrations; High doses; Ionizing radiation