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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Animals, Antineoplastic Agents, Combined Modality Therapy, DNA Damage, DNA Repair, DNA, Neoplasm, Deoxycytidine, Electrophoresis, Gel, Pulsed-Field, Fibrosarcoma, Mice, Mice, Inbred C3H, Radiation Tolerance, Radiation-Sensitizing Agents, Tumor Cells, Cultured, Vidarabine.
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Is radiosensitization of mouse sarcoma cells by fludarabine ( F-ara-A ) or gemcitabine ( dFdC ) , two nucleoside analogues , mediated by an increased induction or a repair inhibition of DNA double-strand breaks as measured by pulsed-field gel electrophoresis? Context: To investigate the effect of fludarabine (F-ara-A) and gemcitabine (dFdC), two radiosensitizing nucleoside analogues, on the induction and repair of DNA dsb after ionizing radiation. Radiosensitization of mouse sarcoma SA-NH and FSA cells was studied using a clonogenic assay. Cell survival curves were fitted with the linear-quadratic model. DNA dsbs were detected by pulsed-field gel electrophoresis under neutral conditions. F-ara-A (100 micromol dm(-3) for 1 h prior to irradiation) induced a substantial radiosensitization in SA-NH cells with a dose modification factor of 2.0 for a surviving fraction of 0.5. In a FSA mouse sarcoma cell line, dFdC (5 micromol dm(-3) for 3 h prior to irradiation) induced a modest radiosensitization with a DMF of 1.2 for a surviving fraction of 0.5. Under similar experimental conditions, neither F-ara-A nor dFdC altered the yield of radiation-induced DNA dsbs in the dose range of 0-40 Gy. After a single dose of 25 Gy (SA-NH cells) or 40 Gy (FSA cells), neither the kinetics of repair nor the amount of residual damage was affected by F-ara-A or dFdC.
assistant
For experimental conditions under which radiosensitization was observed, neither the induction nor the repair of DNA dsbs after ionizing radiation were affected by F-ara-A or dFdC. Final Decision: no