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The quantitation and kinetics of unscheduled (repair) DNA synthesis in ultraviolet‐irradiated human skin by automated image analysis
Author(s) -
CHADWICK C.A.,
DIGGLE S.P.,
YOUNG A.R.,
POTTEN C.S.
Publication year - 1996
Publication title -
british journal of dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.304
H-Index - 179
eISSN - 1365-2133
pISSN - 0007-0963
DOI - 10.1046/j.1365-2133.1996.d01-1032.x
Subject(s) - incubation , thymidine , kinetics , irradiation , incubation period , epidermis (zoology) , dna , dna repair , ultraviolet , biology , dna damage , biophysics , chemistry , microbiology and biotechnology , biochemistry , anatomy , optics , physics , quantum mechanics , nuclear physics
Summary Grain counting by eye is a tedious and time‐consuming technique but one with great potential in cell kinetics and for the study of DNA excision repair activity (unscheduled DNA synthesis or UDS). We have been investigating the levels of UDS in human skin sections exposed in situ to ultraviolet radiation using a short‐term incubation in tritiated thymidine and autoradiography and the decline in UDS levels with time (repair Kinetics). We have adapted an automated image analysis system automatically to assess the number of grains over epidermal cell nuclei in autoradiographs of sections of epidermis. An excellent correlation was observed between visual counting and machine measurement of the area (in pixels) occupied by silver grains. The levels of UDS declined with time as lesions are progressively repaired. The half time (± standard deviation) for the reduction in UDS is 7.25± 0.18 h. The grain counts can be significantly increased by increasing the autoradio‐graphic exposure, by increasing the concentration of tritiated thymidine and by increasing the incubation time.