* Changes to the DNA; determination of DNA adducts or DNA strand breakages, or measurement of unscheduled DNA synthesis
as a cellular response to DNA damage.
Various studies have been carried out with regard to the cytotoxic and genotoxic effects of individual components and extracts of areca nut, which include aqueous ethanolic and acetic acid extracts of the nut.17-19 Areca nut extract also induces unscheduled DNA synthesis
by cultured gingival keratinocytes.
One explanation for the increased DNA damage in the presence of morphine is that the opioid interferes with repair processes (reviewed in Madden et al., 2002): DNA repair capacity, as measured by unscheduled DNA synthesis
following exposure to UV light, is reduced in lymphocytes from heroin addicts (Madden et al., 1979) or those exposed to morphine in vitro (Madden and Falek, 1991).
According to ICH (International Conference on Harmonization) guidelines, in the event of a 'positive' result in a regulatory in vitro assay, 'a further in vivo test, in addition to the in vivo cytogenetic assay, using a tissue other than the bone marrow (or peripheral blood if used) can provide further useful information.' The liver UDS (Unscheduled DNA Synthesis
) test is often used in these circumstances, though DNA adduct measurements, transgenic mutation models, and increasingly the COMET assay are also used.
Spontaneous DNA synthesis (DS) and unscheduled DNA synthesis
(UDS) were assayed with a liquid scintillation counter (Beckman Coulter Inc., Fullerton, CA, USA; Zhang et al.
Thioacetamide (TAA) was used to induce tumor promotion response and oxidative stress and caused significant depletion in the detoxification and antioxidant enzyme armory with concomitant elevation in malondialdehyde (MDA) formation, hydrogen peroxide ([H.sub.2][O.sub.2]) generation, ornithine decarboxylase (ODC) activity and unscheduled DNA synthesis
. However, B.
(11a.) Chromosome aberrations, Sister chromatid exchanges, unscheduled DNA synthesis
and morphological neoplastic transformation in Syrian hamster embryo cells.
Complying with FDA 21 CFR Part 11 final rule, for R&D and quality assurance testing, the system is suitable for colony counting and sizing, unscheduled DNA synthesis
, Ames testing Chemotaxiz, Elispot assay, MIC assays, and other life science applications.