Sendai virus-mediated fusion between mitotic and interphase mammalian cells causes the rapid condensation of the interphase chromosomes into distinct structures, a process termed premature chromosome condensation. This phenomenon has been used to assess the immediate action of x-rays and ultraviolet light on the chromosomes of HeLa cells irradiated in the G1 phase of the life cycle. X-irradiati...

Survival and unscheduled DNA synthesis (UDS) were measured in a cultured insect cell line, TN-368, and a cultured mammalian cell line, V-79-4, following exposure to several fluences of ultraviolet light. TN-368 cells were approximately seven times more resistant to the lethal effects of UV than V-79 cells, as determined by colony formation. The amount of UDS per unit amount of DNA is about the ...

Xeroderma pigmentosum (XP) and trichothiodystrophy (TTD) are rare genodermatoses transmitted as recessive and autosomal traits that result in reduced capacity to repair UV-induced DNA lesions. Although XP, but not TTD, patients are prone to basal and squamous cell carcinomas, to date no comparative studies of the XP and TTD phenotypes have included epidermal keratinocytes. We compared the DNA r...

The interference of platelets with the estimation of unsched uled DNA synthesis in human peripheral mononuclear leukocytes following genotoxic exposure was studied. A 96% reduction in the unscheduled DNA synthesis value was achieved by incubat ing [3H]thymidine with platelet-rich plasma for 5 hr at 37°.Using radioactive thymine-containing compounds, together with quan titative analyses based o...

1-[(4-Amino-2-methylpyrimidin-5-yl)methyl]-3-(2-chloroethyl)-3- nitrosourea hydrochloride (ACNU), a cancer chemotherapeutic bifunctional alkylating agent, causes chloroethylation of DNA and subsequent DNA strand cross-linking through an ethylene bridge. We isolated and characterized two ACNU-sensitive mutants from mutagenized Chinese hamster ovary cells and found them to be new drug-sensitive r...

Unscheduled DNA synthesis (UDS) induced by melphalan, nitrogen mustard and ultra-violet irradiation was studied in bone marrow cells from myeloma patients. In a previous study, normal bone marrow cells in various stages of maturation were found to display a gradual decrease in UDS parallel with the process of maturation. Myeloma cells showed a similar pattern. Poorly differentiated myeloma cell...

1. OECD Test Guidelines (TGs) are available for a wide range of in vitro genotoxicity assays that are able to detect DNA damage, gene mutation and/or chromosomal aberrations. There are TGs for in vivo endpoints (i.e. chromosomal aberrations, gene mutations and DNA repair as unscheduled DNA synthesis); however, these do not directly measure DNA damage. The alkaline single cell gel electrophoresi...