Linked Life Data

8367588

Source:http://linkedlifedata.com/resource/pubmed/id/8367588

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1993-10-7
pubmed:abstractText
A DNA double-strand break (DSB) repair-deficient CHO cell line, xrs-5, was used to evaluate the effect of hypertonic treatment on the radiation yield of interphase chromosome breaks, as visualized by means of premature chromosome condensation (PCC). For this purpose, interphase chromosome breaks were measured in plateau-phase G1 cells after exposure to 10 Gy X rays using either the standard protocol for PCC induction or a revised protocol that includes a brief (20 min) treatment in hypertonic medium (500 mM NaCl) during chromosome condensation. Experiments at the chromosome level were complemented by experiments at the DNA and the cellular level performed under similar postirradiation conditions. The results obtained were compared to those reported previously for CHO cells. Radiation yields of interphase chromosome breaks, as measured using standard protocols for PCC induction, were higher in xrs-5 than in CHO cells. However, the yields became similar between the two cell lines when a 20-min incubation in hypertonic medium was introduced immediately after fusion with mitotic cells. This equalization was due to the fact that incubation in hypertonic medium did not affect the radiation yield of interphase chromosome breaks in xrs-5 cells but increased it in CHO cells to levels similar to those measured in xrs-5 cells. This result suggests that xrs-5 cells constitutively express as interphase chromosome breaks a subset of DSBs which in repair-proficient CHO cells requires incubation in hypertonic medium for transformation to interphase chromosome breaks. Rejoining of DSBs, when measured in isotonic medium, was incomplete in xrs-5 cells compared to CHO cells. Rejoining of DSBs normally repaired in xrs-5 cells was completely inhibited during treatment in hypertonic medium. Postirradiation treatment in hypertonic medium affected the survival of xrs-5 cells only modestly, suggesting that the sector of PLD (beta-PLD) which required treatment in hypertonic medium for fixation in repair-proficient CHO cells is fixed constitutively in xrs-5 cells. These results are in agreement with a model developed to interpret results obtained in similar experiments with CHO cells (Iliakis et al., Radiat. Res 135, 160-170, 1993). The model postulates that potentiation in CHO cell killing induced by hypertonic treatment is caused by the transformation of a subset of fast-repairing DSBs to irreparable interphase chromosome breaks and assumes that this transformation is equivalent to fixation of beta-PLD.(ABSTRACT TRUNCATED AT 400 WORDS)
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0033-7587
pubmed:author
pubmed:issnType
Print
pubmed:volume
135
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
171-7
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
Hypertonic treatment does not affect the radiation yield of interphase chromosome breaks in DNA double-strand break repair-deficient xrs-5 cells.
pubmed:affiliation
Thomas Jefferson University, Department of Radiation Oncology and Nuclear Medicine, Philadelphia, Pennsylvania 19107.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.