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Rate and extent of DNA repair in nondividing human diploid fibroblasts

Journal Article · · Cancer Res.; (United States)
OSTI ID:5921860
;
Rates of DNA repair in ultraviolet irradiated nondividing human diploid fibroblasts were determined at doses as low as 1 J/sq m using an enzymatic assay for pyrimidine dimers. In normal cells, initial rates increased with dose to 20 J/sq m with no further increase at 40 J/sq m. At 10 J/sq m or less, repair occurred continuously over long postultraviolet periods until all the damage that could be detected was removed. The overall rate curves appear as the sum of two first-order reactions with different rate constants. The slow reaction extrapolates to 30 to 40% of the original dimers. Populations irradiated a second time after greater than 90% of the original damage had been removed repaired the newly added DNA damage with similar kinetics and to the same extent. Repair kinetics in a xeroderma pigmentosum strain lacks the rapid component and approximates the slow component of normal cells. If the slow component of normal cells is due to repair of less accessible dimers, as suggested by others, then by analogy, slow excision repair in XP12BE may be due to the poor accessibility of all dimers. This suggests that the XP12BE excision repair defect is in the enzymes that render dimers in chromatin accessible to repair.
OSTI ID:
5921860
Journal Information:
Cancer Res.; (United States), Journal Name: Cancer Res.; (United States) Vol. 41:3; ISSN CNREA
Country of Publication:
United States
Language:
English

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Related Subjects

550200 -- Biochemistry
560121* -- Radiation Effects on Cells-- External Source-- (-1987)
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMAL CELLS
ANIMALS
AZINES
BIOASSAY
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CELL CULTURES
CONNECTIVE TISSUE CELLS
DIMERS
DISEASES
DNA
DOSE-RESPONSE RELATIONSHIPS
ELECTROMAGNETIC RADIATION
ENZYME ACTIVITY
FIBROBLASTS
GENETIC EFFECTS
GENETIC RADIATION EFFECTS
HETEROCYCLIC COMPOUNDS
KINETICS
MAMMALS
MAN
NUCLEIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PRIMATES
PYRIMIDINES
RADIATION EFFECTS
RADIATIONS
REACTION KINETICS
RECOVERY
REPAIR
SKIN DISEASES
SOMATIC CELLS
ULTRAVIOLET RADIATION
VERTEBRATES
XERODERMA PIGMENTOSUM