General Radiation Cytopathology
George W. Casarett in Radiation Histopathology, 2019
Abnormalities of cell division could be due not only to defects in centrosomes or nuclear chromatin (chromosomes) but sometimes may be reflections of alterations in membranes, as follows: In incomplete division, with refusion to form a binucleate cell, the failure of complete cytoplasmic (telophase) separation might be due to an increased adhesiveness of the cytoplasmic membrane.The formation of micronuclei could be related partly to alterations in nuclear membrane and partly to fragmentation of nuclear chromatin material.The production of mononucleated giant cells, in its simplest form, representing growth without division, has been considered to be due at least party to alteration in the cytoplasmic apparatus of cell division.Multinucleated giant cells may be formed by fusion of cells with altered cytoplasmic membranes.
Neuroendocrine Morphology
Paul V. Malven in Mammalian Neuroendocrinology, 2019
Although the coexistence of LH and FSH in one gonadotroph was initially surprising, each hormone contains one subunit that also occurs in the other hormone. The discovery that the evolutionarily related prolactin (PRL) and somatotropin (GH) could sometimes occur in a single cell (Frawley et al., 1985) was more surprising because these hormones are different molecules arising from different genes. Cells that contain only PRL are known as mammotrophs because PRL has strong actions on mammary function. The secretory vesicles of mammotrophs found in the rat pars anterior are unique because of their irregularly shaped (i.e., pleomorphic) secretory vesicles located peripherally within the cytoplasm. However, pleomorphic secretory vesicles are not a general feature of mammotrophs because the secretory vesicles in sheep mammotrophs are spherical rather than pleomorphic. Cells that contain only GH are known as somatotrophs and usually have spherical secretory vesicles whose size varies with species. Cells that contain both PRL and GH are known as mammo-somatotrophs, and they have been observed in several species. Rat mammo-somatotrophs are quite small cells containing inconspicuous rough endoplasmic reticulum (RER) and Golgi apparatus. Individual secretory vesicles of rat mammosomatotrophs appear to contain both PRL and GH. In contrast to the rat, bovine mammosomatotrophs are not as small and are often binucleated cells (Kineman et al., 1990).
Approaches for Identification and Validation of Antimicrobial Compounds of Plant Origin: A Long Way from the Field to the Market
Mahendra Rai, Chistiane M. Feitosa in Eco-Friendly Biobased Products Used in Microbial Diseases, 2022
The in vitro and in vivo micronucleus test is considered the gold standard for the analysis of genotoxicity. It analyzes the genotoxic potential by the frequency of nuclear changes resulting from chromosomal changes in the previous mitosis, including chromosome breaks or loss of whole chromosomes. Nuclear changes are mainly observed as micronucleus formation but also by the presence of nuclear buds and nucleoplasmic bridges (Fenech 2007), as well as the detection of apoptosis, necrosis and cytotoxicity. Regulatory agencies recommend that in vitro tests should include the step of blocking cytokinesis for the formation of binucleated cells, denominated cytokinesis-block micronucleus assay (CBMN) (EMA 2013; OECD 2016a), which allows the identification of the cells exposed to the candidate compound for one or more division cycles (Fenech 2007). The cytotoxicity (CBPI) by analyzing the number of cell cycles using CBMN assays is one of the tests recommended by international agencies (OECD 2016a; 2016b).
Correlation between cytogenetic biomarkers obtained from DC and CBMN assays caused by low dose radon exposure in smokers
Published in International Journal of Radiation Biology, 2019
Clearly distinguishable cytoplamic boundary of binucleate cell from the cytoplasmic boundary of adjacent cellsTwo nuclei with equal in size (approximately), staining pattern and intensity.Two daughter nuclei in a binucleate cell without overlap with each other, but it may touchStaining intensity of micronuclei as same as that of main nuclei. Micronuclei not linked or connected to main nuclei.Micronuclei may touch but not overlap with main nuclei and presence of micronuclei within the cytoplamic boundary of binucleate cells.
Assessment of bendamustine-induced genotoxicity in eukaryotic cells
Published in Drug and Chemical Toxicology, 2019
Tais Susane Pereira, Juliane Rocha de Sant’anna, Janicelle Fernandes Morais, Joana Paula Rocha de Sant’anna Yajima, Paulo Cezar de Freitas Mathias, Claudinéia Conationi da Silva Franco, Marialba Avezum Alves de Castro-Prado
The Mnvit technique was performed according to the protocol described by Fenech (2000, 2007) with some modifications. After incubation of 24 hours, each lymphocyte culture was individually treated with bendamustine (6.0 μg/ml, 9.0 μg/ml, and 12.0 μg/ml) and mitomycin C (0.1 μg/ml) (positive control), whereas an untreated culture was included as the negative control. To inhibit cytokinesis, cytochalasin B (final concentration 6 μg/ml) was added to each culture after 44 hours of incubation. The cultures were harvested by centrifugation 72 hours after the beginning. The lymphocyte cultures were subjected to a mild hypotonic solution (75 mM KCl) and fixed three times in a cold solution of methanol: glacial acetic acid (3:1 v/v). The cells were centrifuged again, re-suspended in a small volume of fixative, spread on to pre-cleaned slides, which were dried in cold air and stained with 5% Giemsa (pH 6.8; Sorensen’s buffer). Two independent cultures of each treatment were done per donor. A minimum of 1000 binucleated cells with preserved cytoplasm were scored from each culture and the frequencies of micronucleated binucleate cells were determined. The cytokinesis block proliferation index (CBPI) and the amount of cytostasis induced by the treatment were determined according to Lorge et al. (2008):
A follow-up study on workers involved in the graphene production process after the introduction of exposure mitigation measures: evaluation of genotoxic and oxidative effects
Published in Nanotoxicology, 2022
Delia Cavallo, Cinzia Lucia Ursini, Anna Maria Fresegna, Aureliano Ciervo, Fabio Boccuni, Riccardo Ferrante, Francesca Tombolini, Raffaele Maiello, Pieranna Chiarella, Giuliana Buresti, Valentina Del Frate, Diana Poli, Roberta Andreoli, Luisana Di Cristo, Stefania Sabella, Sergio Iavicoli
The results of BMCyt assay are reported in Table 2 and show the median values of all the analyzed anomalies grouped accordingly the kind of effect that they reflect (genotoxicity and cytotoxicity). In the follow-up study we obtained evaluable results only in five of six enrolled subjects due to the scarceness of collected cells during the second sampling of one of the workers. The comparison between the first biomonitoring and this one shows, in the five subjects resulted evaluable in both the biomonitoring campaigns, a decrease of almost all the genotoxic parameters (although not statistically significant). Particularly interesting is the reduction of the percentage of MN positive subjects that became 0% starting from 60%. We also found a statistically significant reduction of the frequency of binucleated cells.