The unscheduled DNA synthesis test is a short-term genotoxicity assay that allows identification of substances that induce DNA repair in liver cells of treated animals. This endpoint can be assessed by determining the uptake of radiolabelled nucleotide after excision-repair in cells that are not undergoing scheduled (S-phase) DNA synthesis. Here we describe the protocol for performing this well...

The induction of unscheduled DMA synthesis in primary cultures of urothelial cells from rats, mice, and dogs by nitrofurans and arylamines and their derivatives was examined. Electron microscopy of the culture from rat cells showed the characteristics of epithelial cells. The cultured cells were ex posed to the test chemicals in a serum-free medium containing 10 HIMhydroxyurea and [3H]thymidine...

In mammalian cells, S-phase DNA synthesis occurs at sites fixed to a sub-nuclear structure, the nuclear matrix or cage. This is an ordered network of non-histone proteins, which maintains its essential morphology even in the absence of DNA. We show here that unscheduled DNA synthesis following exposure of HeLa cells to ultraviolet light also takes place at this sub-structure. We also show that ...

An assay has been developed in which excision repair deficiency of xeroderma pigmentosum cells is transiently complemented, as measured by unscheduled DNA synthesis, by microinjection of cytoplasmic poly(A)+ RNA derived from HeLa cells. Four different complementation groups of xeroderma pigmentosum have been assayed. Groups A and G showed complementation, whereas groups D and F did not. Surviva...

The interference of platelets with the estimation of unscheduled DNA synthesis in human peripheral mononuclear leukocytes following genotoxic exposure was studied. A 96% reduction in the unscheduled DNA synthesis value was achieved by incubating [3H]thymidine with platelet-rich plasma for 5 hr at 37 degrees. Using radioactive thymine-containing compounds, together with quantitative analyses bas...

A comparative study was performed with a variety of human cell lines on the effects of treatments with cis-diamminedichloroplatinum(II) (cisplatin) on cell survival and the induction of unscheduled DNA synthesis. In addition to control fibroblasts (Han, MB), cell lines defective in DNA repair were used [xeroderma pigmentosum, XP(A) and XP(F), and Fanconi's anemia (FA)], as well as cells deficie...

The nitrotoluenes failed to induce unscheduled DNA synthesis in in vitro cultures of rat hepatocytes. Because intestinal bacteria are known to be involved in the metabolic activation of other nitroaromatic compounds, the genotoxicity of the nitrotoluenes was evaluated using an in vivo-in vitro hepatocyte DNA repair assay. 2-Nitrotoluene (2NT), 3-nitrotoluene, or 4-nitrotoluene was administered ...

Anthracycline antitumor antibiotics, such as Adriamycin and daunomycin, are potent genotoxic agents and carcinogens. A variety of anthracycline derivatives was investigated in various in vitro short-term tests, i.e., mutagenesis in Salmonella typhimurium and V79 Chinese hamster cells and induction of unscheduled DNA synthesis in primary rat hepatocytes. Compounds containing a daunosamine sugar ...

Human peripheral blood lymphocytes enriched in T or B cells were exposed to ultraviolet irradiation, nitrogen mustard or methylmethane sulphonate and investigated regarding their capacity for DNA repair synthesis. The DNA repair synthesis, measured as [3H] thymidine incorporated, was determined by autoradiography as unscheduled DNA synthesis (UDS). No systematic difference could be found in the...