cell proliferation

/Tag:cell proliferation

Chemical Contamination Suspected in Cytotoxic Effects of Incubators on BALB 3T3 Cells

Kiyoshi Sasaki

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The Comet Assay with MCL-5 Cells as an Indicator of Genotoxic Treatment with Chemicals and Cigarette Smoke Condensate

Lucie Wolz, Günter Krause and Gerhard Scherer

The metabolically competent human lymphoblastoid cell line MCL-5 was treated with a panel of mutagens to assess the induction of DNA damage. Treatment effects were observed by monitoring cell proliferation and by single-cell gel electrophoresis (SCGE). The direct-acting mutagens benzo[a]pyrene-7,8-diol 9,10-epoxide (BPDE) and 1-methyl-3-nitro-1-nitrosoguanidine (MNNG), as well as pro-mutagens requiring metabolic activation, i.e. benzo[a]pyrene (BaP), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 4-N-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and cigarette-smoke condensate (CSC), were assayed by SCGE. Assay schemes were adapted for the MCL-5 cell line and for low levels of strand break induction, by inclusion of the DNA synthesis inhibitors cytosine arabinoside and hydroxyurea, and by extending the electrophoresis time. For all mutagens tested, dose-dependent increases of median and average tail moment values among 50 nucleoids per slide were observed. The determining factors for selecting the treatment doses for mutation-induction experiments were the solubility of BaP and PhIP in the exposure medium, and the cytotoxicity exhibited by BPDE, MNNG and CSC. Induction of DNA strand breaks was obtained at mutagen concentrations permitting sufficient cell proliferation, except in the case of MNNG.
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Oestradiol Potentiates the Effects of Certain Pyrethroid Compounds in the MCF7 Human Breast Carcinoma Cell Line

Irma Kakko, Tarja Toimela and Hanna Tähti

Pyrethroids are the most widely used insecticides for indoor pest control, so human exposure to them is common. The main target of pyrethroids is the nervous system, but their endocrine disrupting capabilities may also be of toxicological concern. In the present study, the proliferation of the breast cancer cell line, MCF7, was studied after a 7-day exposure to various concentrations of pyrethrin, permethrin and cypermethrin. The effects of oestradiol and the combined effects of oestradiol (0.10nM) and pyrethroids (0.1–100μM) on MCF7 cell proliferation were also evaluated. Proliferation and cell toxicity were studied by measuring the ATP content with a luminescence method, and mitochondrial metabolic enzyme activity with the WST-1 test. In the ATP test, low concentrations (0.1–1μM) of pyrethroids in co-exposure with oestradiol caused a clear statistically significant increase in the proliferation of MCF7 cells. This was evident when compared to the proliferative effect caused by 0.1nM oestradiol alone. High concentrations were cytotoxic, and the greatest cell toxicity was that of cypermethrin, which has a cyano group in its molecular structure.
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An Evaluation of the In Vitro Cytotoxicities of 50 Chemicals by using an Electrical Current Exclusion Method versus the Neutral Red Uptake and MTT Assays

Toni Lindl, Birgit Lewandowski, Sonya Schreyögg and Andrea Stäudte

According to the 2001 National Institutes of Health guidance document on using in vitro data to estimate in vivo starting doses for acute toxicity, the performance of the electrical current exclusion method (ECE) was studied for its suitability as an in vitro cytotoxicity test. In a comparative study, two established in vitro assays based on the quantification of metabolic processes necessary for cell proliferation or organelle integrity (the MTT/WST-8 [WST-8] assay and the neutral red uptake [NRU] assay), and two cytoplasm membrane integrity assays (the trypan blue exclusion [TB] and ECE methods), were performed. IC50 values were evaluated for 50 chemicals ranging from low to high toxicity, 46 of which are listed in Halle’s Registry of Cytotoxicity (RC). A high correlation was found between the IC50 values obtained in this study and the IC50 data published in the RC. The assay sensitivity was highest for the ECE method, and decreased from the WST-8 assay to the NRU assay to the TB assay. The consistent results of the ECE method are based on technical standardisation, high counting rate, and the ability to combine cell viability and cell volume analysis for detection of the first signs of cell necrosis and damage of the cytoplasmic membrane caused by cytotoxic agents.
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