title: Monitoring hprt mutant frequency over time in T-lymphocytes of people accidentally exposed to high doses of ionizing radiation.
abstract: Modern technologies have provided the opportunity to monitor mutations in people in vivo. The subjects of this study were accidentally exposed to 137Cesium in a radiological accident that occurred in September 1987 in Goiânia, Brazil, during which more than 150 people received doses greater than 0.1 Gy and as high as 7 Gy. The objective of this study was to determine how long the hprt mutant T-cells in the peripheral blood contribute to mutant frequency by examining the time-course of the T-lymphocyte response to ionizing radiation. This report describes the results obtained over a period of 2.3 to 4.5 years subsequent to the accident, from 11 subjects with doses ranging from 1 to 7 Gy, and from nine control subjects selected from the same population. The mean In MF (+/- SE) of the control group was 2.5 (+/- 0.2) + In10(-6). The exposed group had a significantly increased mutant frequency; the mean In MF (+/- SE) were 3.3 (+/- 0.3) + In10(-6), 2.8 (+/- 0.2) + In10(-6), and 2.3 (+/- 0.2) + In10(-6), in the years 1990-1992 respectively. Based on the decline of mutant frequency and using Buckton's models [Buckton et al. (1967): Nature 214:470-473], we demonstrated that mutant T-cells have a short-term memory with a half-life of 2.1 years. This relatively short half-life limits the effective use of the hprt assay as the method of choice to monitor past exposure. The data also demonstrate a positive correlation with age, and an inverse correlation with plating efficiency.
authors.affiliation: Centre for Environmental Health, University of Victoria, British Columbia, Canada.
authors.forename: A D
authors.initials: AD
authors.lastname: da Cruz
authors.forename: J
authors.initials: J
authors.lastname: Curry
authors.forename: M P
authors.initials: MP
authors.lastname: Curado
authors.forename: B W
authors.initials: BW
authors.lastname: Glickman
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001938:Brazil; D002588:Cesium Radioisotopes / Q000009:adverse effects*; D002999:Clone Cells; D004781:Environmental Exposure; D005260:Female; D005500:Follow-Up Studies; D005720:Gamma Rays / Q000009:adverse effects*; D005796:Genes / Q000528:radiation effects*; D005820:Genetic Testing; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D016296:Mutagenesis; D011829:Radiation Dosage; D018788:Radioactive Hazard Release; D011878:Radiotherapy / Q000295:instrumentation; D013601:T-Lymphocytes / Q000201:enzymology*
chemical_list: D002588:Cesium Radioisotopes; D007041:Hypoxanthine Phosphoribosyltransferase