Effects of areca nut, inflorescence piper betle extracts and arecoline on cytotoxicity, total and unscheduled DNA synthesis
in cultured gingival keratinocytes.
Cell suspensions were prepared as in the assay for unscheduled DNA synthesis and treated with mitomycin C or saline for 2 h at 37[degrees]C.
Although the fraction of proliferating, unstimulated splenocytes is low (Pabst and Fritz, 1988) and unscheduled DNA synthesis has previously been quantitated by liquid scintillation counting in mutagen-treated lymphocytes in the absence of hydroxyurea (Holmberg et al.
Since unscheduled DNA synthesis reflects the entire repair process (incision, excision, synthesis), exclusive of ligation, the effect of morphine on the induction of DNA strand breaks was then measured to determine if incision was affected.
Unscheduled DNA synthesis increased gradually with increasing As concentrations in urine and hair (Table 1), whereas spontaneous DNA synthesis showed a dramatic decrease from approximately 1,150 cpm for the external control group to approximately 200 and 300 for all four exposed groups.
The unscheduled DNA synthesis showed a rather gradual increase as As exposure increased and symptoms worsened.
4 (a,c) (62) Abbreviations: CA, chromosome aberration; DPC, DNA-protein cross-link; DS, spontaneous DNA synthesis; MN, micronucleus; n = number of subjects in each group; SCE, sister chromatid exchange; UDS, unscheduled DNA synthesis.
Benzene-, catechol-, hydroquinone- and phenol-induced cell transformation, gene mutations, chromosome aberrations, aneuploidy, sister chromatid exchanges and unscheduled DNA synthesis
in Syrian hamster embryo cells.