Analysis of bromodeoxyuridine incorporation into DNA: comparison of gas chromatographic/mass spectrometric, CsCl gradient sedimentation, and specific radioactivity methods.
A sensitive new method for the quantitation of 5-bromodeoxyuridine (BrdUrd) incorporated into DNA by GC/MS analysis of enzymatically released Thy and bromouracil (BrUra) is presented. The hydrolysis procedure was characterized and found to give uniform results when sample size was 1-10 micrograms DNA and incubation time for DNA digestion was between 40 min and 16 h. Samples of DNA containing 3H-labeled BrdUrd were analyzed in parallel by the GC/MS technique and by specific radioactivity and buoyant density measurements, in order to compare the three methods. The GC/MS procedure gave values for percentage replacement of Thy by BrUra which were higher than those obtained by specific activity and lower than those obtained by buoyant density. This GC/MS method can detect 1% replacement in a 1-microgram DNA sample, equivalent to approximately 10(5) cells or 0.1 mg tissue, and will permit sensitive and quantitative analysis of the presence of this chemotherapeutic agent/radiosensitizer in cellular DNA from biopsy samples of normal or tumor tissue.
D000818:Animals; D001973:Bromodeoxyuridine / Q000032:analysis*; D001976:Bromouracil / Q000032:analysis; D002499:Centrifugation, Density Gradient; D002586:Cesium; D002712:Chlorides; D004247:DNA / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry; D006868:Hydrolysis; D051379:Mice; D013936:Thymidine / Q000032:analysis; D014316:Tritium
D002712:Chlorides; D014316:Tritium; D002586:Cesium; D001976:Bromouracil; D004247:DNA; D001973:Bromodeoxyuridine; C028019:cesium chloride; D013936:Thymidine