China
Africa
Explore chapters and articles related to this topic
Methods and Protocols for In Vivo Animal Nanotoxicity Evaluation: A Detailed Review
Published in Vineet Kumar, Nandita Dasgupta, Shivendu Ranjan, Nanotoxicology, 2018
Fátima Torrico Medina, Isabel Andueza, Alirica I. Suarez
As the micronucleus can only be expressed in division of eukaryotic cells, it was necessary to have a method that could distinguish within a population the cells in mitosis and cells that have completed a nuclear division from the cells in the interphase. In response to this problem, numerous methods based on flow cytometry and DNA labeling have been proposed, but the micronucleus with blocking of cytokinesis (MNBC) is the most accepted method, due to its simplicity and reliability with respect to its effects on genetic damage in the germ line. Cytochalasin-B is used and the cells are consequently identified by their binucleate appearance (Fenech and Morley 1985a,b). Consequently, the micronucleus is counted only in binucleate cells, allowing reliable comparisons of chromosomal damage between cell populations that differ in nuclear division kinetics. Cytochalasin-B inhibits cytokinesis and is used to generate the binucleated cells, but it also inhibits endocytosis, an important mechanism of uptake of nanoparticles into the cell (Doak et al. 2009; Gonzalez et al. 2011). Cells should be incubated with nanoparticles prior to the addition of Cytochalasin-B to ensure their uptake, and then micronucleus formation examination is performed (Magdolenova et al. 2012).
Licochalcone A, a licorice flavonoid: antioxidant, cytotoxic, genotoxic, and chemopreventive potential
Published in Journal of Toxicology and Environmental Health, Part A, 2020
Karoline Soares de Freitas, Iara Silva Squarisi, Nathália Oliveira Acésio, Heloiza Diniz Nicolella, Saulo Duarte Ozelin, Matheus Reis Santos de Melo, Ana Paula Prado Guissone, Gabriela Fernandes, Lívia Mara Silva, Ademar Alves da Silva Filho, Denise Crispim Tavares
The CHO cell micronucleus (MN) test was employed to determine genotoxic and antigenotoxic potential of LicoA, following the recommendations of OECD 487 (OECD 2016b). Cell culture and treatment procedures are those described by Reis et al. (2015). Cells were seeded and cultured for 24 hr prior to treatments. The concentrations of LicoA used in the assessment of genotoxicity were 4.43, 7.39, 10.34, and 11.82 µM (1.5, 2.5, 3.5, and 4 µg/ml). These concentrations were selected using cytotoxicity as a criterion. For antigenotoxicity assessment, cell cultures were treated with 1.85, 3.69, or 7.39 µM (0.62, 1.25, or 2.5 µg/ml) of LicoA, combined with doxorubicin hydrochloride (DXR; Bergamo®, 0.08 μM [0.04 µg/ml]) or methyl methanesulfonate (MMS; CAS:66–27-3, Sigma-Aldrich®, 399.5 µM [44 µg/ml]). Negative (no treatment), solvent (1% DMSO), and positive (DXR and MMS) controls were included. Cells were exposed to the treatments for 3 hr in medium without serum and subsequently incubated in complete medium containing cytochalasin B (CAS: 14930–96-2, Sigma-Aldrich®, 6.25 μM [3 µg/ml]), for 17 hr, in order to block cytokinesis. The total culture duration for the MN test was 44 hr. The protocol was performed in triplicate on three different days. The cell fixation procedures and the analyses were conducted according to the criteria proposed by Fenech (2000). A total of 3,000 binucleated cells were scored per treatment, corresponding to 1,000 cells per treatment per repetition. The nuclear division index (NDI) was also calculated to establish cytotoxicity of the treatments. For the calculation of NDI, 1,500 cells per treatment were analyzed, totalizing 500 cells per repetition. Cells with well-preserved cytoplasm containing 1 to 4 nuclei were scored. The NDI was calculated according to Eastmond and Tucker (1989). The cytotoxicity index (CI) of the treatment was calculated as proposed by Kirsch-Volders et al. (2003):