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Determination
Published in David Woolley, Adam Woolley, Practical Toxicology, 2017
In chromosome aberration tests, the cells, which may be human peripheral lymphocytes, are exposed to the test substance for up to 24 hours and may have a treatment-free period. They are then treated with a spindle poison, which arrests the cell division in metaphase. Metabolic activation is again provided by S9 mix. The cells are taken onto microscope slides and stained. An appropriate number of metaphases, which may be 100 cells from two or three culture replicates at each of three treatment concentrations, are scored for the presence of chromosomal aberrations, which are seen as gaps, breaks or exchanges, and abnormalities of number. Although numerical abnormalities due to polyploidy and endoreduplication may be seen with other cell lines, aneuploidy is easier to detect in human cells. A chromosomal gap is an area in which the stain has not been taken up and where there is minimal misalignment of chromatid(s). A chromosomal break is defined as an unstained section accompanied by a clear misalignment of the chromatid(s). General opinion is that gaps are not as significant as breaks, but they are reported anyway, usually as separate totals from the other aberrations. More extreme disruption may be seen, and this is also reported. Cytotoxicity is determined by reductions in mitotic index for human lymphocytes. For cell lines, a variety of methods to assess cytotoxicity are available, including viable cell number, colony-forming ability, and MTT assessment of mitochondrial activity.
Current development in novel drug delivery systems of bioactive molecule plumbagin
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
S. Rajalakshmi, Niraj Vyawahare, Atmaram Pawar, Paresh Mahaparale, Bothiraja Chellampillai
The maximum tolerated doses of PLB in the acute and subacute toxicity testing were 150 (single oral dose) and 25 (daily doses for 28 days) mg/kg body weight, respectively. The 50% lethal dose (LD50) of PLB for the acute and subacute toxicity testing was 250 and 50–100 mg/kg body weight, respectively [6]. PLB is associated with normal tissue toxicity and short biological half-life with rapid elimination in vivo. Being a quinone moiety is reported to be highly toxic and acts as spindle poison by inhibiting cell mitosis at low concentrations and at higher concentrations it exhibits radiomimetic and cytotoxic effects. Literature suggests that the structure of PLB is similar to vitamin K and therefore the chronic administration of PLB leads to prolonged bleeding time by altering platelet adhesiveness and coagulation [20]. Other toxic effects of PLB include diarrhoea, skin rashes, increases in white blood cell and neutrophil counts, increases in serum phosphatase and acid phosphatase levels, hepatic toxicity and cardiotoxicity [21]. In a recent study in mice, hepatotoxicity of PLB through unbalancing of the anti-oxidative system was observed, that is, marked increased plasma ALT and AST levels, hepatic lipid peroxidation and glutathione peroxidise activity; but decreased superoxide dismutase and catalase activities.
In vitro screening of genotoxicity and mutagenicity of pyriproxyfen in human lymphocytes and Salmonella typhimurium TA98 and TA100 strains
Published in Drug and Chemical Toxicology, 2023
Havva Bugda, Banu Guven Ezer, Eyyup Rencuzogullari
In the present study, it was determined that PPX induced both the percentage of CA and MN frequency in human peripheral lymphocytes. Chromosome structure abnormalities occur when chemicals, called clastogens, break the phosphodiester bonds in the DNA molecule that resulted in an increase in CA and MN frequencies. Aneugens act as spindle poison and cause to the numerical chromosomal abnormalities by inhibiting the organization of the spindle microtubules. In our study, PPX caused to the chromosomal abnormalities due to its clastogenic effect, but did not show any aneugenic effect.