title: Estimate of true incomplete exchanges using fluorescence in situ hybridization with telomere probes.
abstract: OBJECTIVE
  To study the frequency of true incomplete exchanges in radiation-induced chromosome aberrations.
  
  
  METHODS
  Human lymphocytes were exposed to 2 Gy and 5 Gy of gamma-rays. Chromosome aberrations were studied using the fluorescence in situ hybridization (FISH) technique with whole chromosome-specific probes, together with human telomere probes. Chromosomes 2 and 4 were chosen in the present study.
  
  
  RESULTS
  The percentage of incomplete exchanges was 27% when telomere signals were not considered. After excluding false incomplete exchanges identified by the telomere signals, the percentage of incomplete exchanges decreased to 11%. Since telomere signals appear on about 82% of the telomeres, the percentage of true incomplete exchanges should be even lower and was estimated to be 3%. This percentage was similar for chromosomes 2 and 4 and for doses of both 2 Gy and 5 Gy.
  
  
  CONCLUSIONS
  The percentage of true incomplete exchanges is significantly lower in gamma-irradiated human lymphocytes than the frequencies reported in the literature.
authors.affiliation: NASA Johnson Space Center, Radiation Biophysics Laboratory, and Kelsey-Seybol Clinic, Houston, Texas 77058, USA.
authors.forename: H
authors.initials: H
authors.lastname: Wu
authors.forename: K
authors.initials: K
authors.lastname: George
authors.forename: T C
authors.initials: TC
authors.lastname: Yang
mesh_terms: D002869:Chromosome Aberrations; D002877:Chromosomes, Human / Q000528:radiation effects*; D015342:DNA Probes; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D008214:Lymphocytes / Q000528:radiation effects / Q000648:ultrastructure*; D016615:Telomere
chemical_list: D015342:DNA Probes