title: DNA repair by articular chondrocytes. III. Unscheduled DNA synthesis following ultraviolet light irradiation of resting cartilage.
abstract: Unscheduled DNA synthesis (UDS) was demonstrated both in fresh slices of rabbit articular cartilage and in resting chondrocytes dissociated from it. Uptake of [3H]thymidine by chondrocytes treated with 10 mM hydroxyurea and irradiated with 254 nm ultraviolet light (20 J/m2) was measured by autoradiography. The UDS in the resting chondrocytes was minuscule compared with that of chondrocytes growing in monolayer culture. It was greater in resting cells from 3- than in 18-month old rabbits but persisted in animals up to 52 months of age. In both resting and cultured chondrocytes, UDS was greatly inhibited by aphidicolin (5 micrograms/ml). The finding of age-related decrease in UDS of resting chondrocytes, contrasted with previously demonstrated lack of it in dividing ones, raises questions about in vitro artefacts in studies of cellular senescence.
mesh_terms: D000375:Aging; D000818:Animals; D016590:Aphidicolin; D001345:Autoradiography; D001834:Body Water / Q000032:analysis; D002358:Cartilage, Articular / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects*; D002478:Cells, Cultured; D004260:DNA Repair; D004261:DNA Replication / Q000187:drug effects / Q000528:radiation effects*; D004224:Diterpenes / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D006918:Hydroxyurea / Q000494:pharmacology; D007700:Kinetics; D009928:Organ Specificity; D011817:Rabbits; D013936:Thymidine / Q000378:metabolism; D014316:Tritium; D014466:Ultraviolet Rays
chemical_list: D004224:Diterpenes; D014316:Tritium; D016590:Aphidicolin; D013936:Thymidine; D006918:Hydroxyurea