Academic literature on the topic 'Micronuclei'
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Journal articles on the topic "Micronuclei"
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CHAU, M. F., and STEPHEN F. NG. "The somatic function of the micronucleus in sexual reproduction of Paramecium tetraurelia: initiation of oral membranelle assembly." Journal of Cell Science 90, no. 1 (May 1, 1988): 157–66. http://dx.doi.org/10.1242/jcs.90.1.157.
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In a previous study, cell lines possessing defective micronuclei, generated by laser-microbeam irradiation, gave rise to cells lacking both oral apparatus and micronuclear derivatives after autogamy. It was concluded that astomy arose as a result of degeneration of all of the meiotic products of the micronuclei after meiotic telophase II, instead of leaving one product for subsequent nuclear reorganization. The present study consolidates this conclusion by employing 15 micronucleus-defective cell lines; these were generated by laser-irradiation of the micronucleus, treatment of the cells with cis-dichlorodiamineplatinum (II), and conjugation between diploids and amicronucleates to produce haploids. A good correlation between the presence of pregametic, gametic and zygotic nuclei and the initiation of oral membranelle assembly in stomatogenesis was demonstrated in 17 cases of autogamy. Therefore, postmeiotic micronuclear activities up to the zygotic nucleus stage, in particular in the gametic stage, are crucial for the initiation of oral membranelle assembly, while premeiotic micronuclear activities are insufficient. Micronuclear genic factors are also likely to be involved in the determination of the fate of the meiotic products.
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Medyankina, Mariya, Nikita Kochetkov, Natalya Golovacheva, and Dmitry Nikiforov-Nikishin. "Evaluation of the genotoxicity of diflubenzuron by micronucleus test on red blood cells Danio rerio." Fisheries 2022, no. 4 (August 10, 2022): 71–75. http://dx.doi.org/10.37663/0131-6184-2022-4-71-75.
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In this paper, the genotoxicity of (1-(4-chlorophenyl)-3-(2,6-difluoro-benzoyl)urea) is investigated by a micronuclear test on Danio rerio, as a standard test object, at concentrations of 0.5, 1 and 2 mg/l. As a result of the work, a significant increase in the frequency of occurrence of micronuclei (0.73%) was found, while other nuclear anomalies in the maximum concentrations of erythrocytes were also significant. It was found that the frequency of micronuclei in concentrations of 0.5 and 1 mg/l on the fifth day of the experiment was the maximum, while at the maximum concentration (2 mg/l) the level of micronuclei was lower, which is probably due to toxic effects. An increase in the level of micronuclei may be associated with the genotoxic effect of DFB decay products. The genotoxicity results obtained using the micronucleus test method were contradictory. For this reason, it is necessary to conduct additional studies using the comet method or experiments on cell cultures.
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Grodsky, Ania. "Causes and Consequences of Nuclear Envelope Rupture and DNA Damage in Micronuclei." Advances in Bioscience and Clinical Medicine 9, no. 4 (October 31, 2021): 12. http://dx.doi.org/10.7575/aiac.abcmed.v.9n.4p.12.
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Micronuclei are small, aberrant nuclear compartments containing mis-segregated chromosomes or chromosomal fragments. During telophase, dysfunctional micronuclear envelope reassembly leaves the micronuclear envelope highly unstable and rupture-prone. Following rupture, micronuclei attempt to repair membrane gaps, but the process is typically unsuccessful and may promote the invasion of ER tubules into the interior of micronuclei. These abnormalities cause ruptured micronuclei to accumulate significant DNA damage in the form of both single-stranded DNA and double-stranded breaks. Because micronuclei are capable of promoting genome instability, it is essential to understand the sources of DNA damage and the mechanism through which it arises in these structures. In this review, I will explore the causes and consequences of micronuclear envelope rupture, beginning with the processes surrounding improper micronuclear envelope reassembly. I will then discuss micronuclear envelope rupture, attempted micronuclear envelope repair and its consequences, and the proposed causes of micronuclear DNA damage.
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Nefić, Hilada, Jasmin Mušanović, Kemajl Kurteshi, Enida Prutina, and Elvira Turcalo. "The effects of sex, age and cigarette smoking on micronucleus and degenerative nuclear alteration frequencies in human buccal cells of healthy Bosnian subjects." Journal of Health Sciences 3, no. 3 (December 15, 2013): 196–204. http://dx.doi.org/10.17532/jhsci.2013.107.
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Introduction: This study was performed to establish a baseline value of micronucleus frequency in buccal cells and to estimate the impact of the most common factors (sex and age, and smoking) on micronucleus and degenerative nuclear alteration frequencies in the sample of healthy Bosnian subjects.Methods: The Buccal Micronucleus Cytome (BMCyt) assay, based on scoring not only micronucleus frequency but also other genome damage markers, dead or degenerated cells, provides a measure of cytotoxic and genotoxic effects.Results: Our results showed the baseline buccal micronucleus frequency was 0.135% or 1.35‰, as well as positive correlations between micronucleus frequencies and formations of degenerative nuclear alterations (nuclear buds, karyolytic and karyorrhectic cells). The number of micronuclei in buccal cells was significantly higher in females than in males. There was positive association between the age and frequency of analysed cytogenetic biomarkers. Buccal cell micronuclei and degenerative nuclear alternations were more frequent among cigarette smokers than non-smokers and significantly higher in female smokers than in male smokers. Cytogenetic damages showed significantly positive correlation between intensity of smoking and the number of nuclear alterations. The years of smoking had a significant influence not only on the number of nuclear alterations but also in micronuclei and nuclear buds in buccal cells.Conclusions: The sex influences the number of micronuclei in human buccal cells. The ageing increased the number of micronuclei and other biomarkers of DNA damage. The cigarette smoking significantly increases the frequencies of micronuclei and nuclear buds, pyknotic, karyolytic and karyorrhectic cells.
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Wojcik, A., M. Kowalska, E. Bouzyk, I. Buraczewska, G. Kobialko, N. Jarocewicz, and I. Szumiel. "Validation of the micronucleus-centromere assay for biological dosimetry." Genetics and Molecular Biology 23, no. 4 (December 2000): 1083–85. http://dx.doi.org/10.1590/s1415-47572000000400055.
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The micronucleus assay is frequently used for purposes of biological dosimetry. Due to high interindividual variability in the spontaneous frequency of micronuclei, its sensitivity in the low dose region is poor. It has been suggested that this problem can be mitigated by selectively analyzing the frequency of those micronuclei which contain only acentric fragments. Using a pan-centromeric FISH probe we have studied the dose dependence of micronuclei with centromeres in peripheral lymphocytes of human donors. In contrast to previous publications, our approach is based on determining the relative frequency of micronuclei with and without centromeric signals. Our results confirm previous observations that in the low dose range of ionizing radiation, the micronucleus-centromere assay is more sensitive than the conventional micronucleus test.
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Agustinus, Albert S., Ramya Raviram, Bhargavi Dameracharla, Jens Luebeck, Stephanie Stransky, Lorenzo Scipioni, Robert M. Myers, et al. "Abstract 3768: Epigenetic dysregulation from chromosomal transit in micronuclei." Cancer Research 82, no. 12_Supplement (June 15, 2022): 3768. http://dx.doi.org/10.1158/1538-7445.am2022-3768.
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Abstract Chromosomal instability (CIN) and epigenetic alterations are characteristics of advanced and metastatic cancers, yet whether they are mechanistically linked is unknown. Here we show that missegregation of mitotic chromosomes, their sequestration in micronuclei, and subsequent micronuclear envelope rupture profoundly disrupt normal histone post-translational modifications (PTMs), a phenomenon conserved across humans and mice as well as cancer and nontransformed cells. Some of the changes to histone PTMs occur due to micronuclear envelope rupture whereas others are inherited from mitotic abnormalities prior to micronucleus formation. Using orthogonal techniques, we show that micronuclei exhibit extensive differences in chromatin accessibility with a strong positional bias between promoters and distal or intergenic regions. Finally, we show that inducing CIN engenders widespread epigenetic dysregulation and that chromosomes which transit in micronuclei experience durable abnormalities in their accessibility long after they have been reincorporated into the primary nucleus. Thus, in addition to genomic copy number alterations, CIN can serve as a vehicle for epigenetic reprogramming and heterogeneity in cancer. Citation Format: Albert S. Agustinus, Ramya Raviram, Bhargavi Dameracharla, Jens Luebeck, Stephanie Stransky, Lorenzo Scipioni, Robert M. Myers, Melody Di Bona, Mercedes Duran, Britta Weigelt, Shira Yomtoubian, Eleonore Toufektchan, Paul S. Mischel, Vivek Mittal, Sohrab Shah, John Maciejowski, Enrico Gratton, Peter Ly, Mathieu F. Bakhoum, Dan Landau, Vineet Bafna, Simone Sidoli, Yael David, Samuel F. Bakhoum. Epigenetic dysregulation from chromosomal transit in micronuclei [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3768.
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KERYER, GUY, NICOLE GARREAU DE LOUBRESSE, NICOLE BORDES, and MICHEL BORNENS. "Identification of a spindle-associated protein in ciliate micronuclei." Journal of Cell Science 93, no. 2 (June 1, 1989): 287–98. http://dx.doi.org/10.1242/jcs.93.2.287.
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Ciliated protozoa display a nuclear dualism, with germinal micronuciei and a somatic macronucleus. During mitosis, which proceeds without disruption of the nuclear envelope, a spindle is organized within the micronucleus from, presumably, intranuclear microtubule-organizing centres (MTOCs). In order to characterize these MTOCs, monoclonal antibodies generated against human centrosomes were screened on several ciliates and particularly on Paramecium tetraurelia. In this ciliate, the monoclonal antibody CTR 532, which decorates centrosomal and spindle-associated components in mammalian cells, specifically labelled the micronuclei during interphase. At the electron-microscope level, it stained a fibrous material surrounding microtubules localized on the inner face of the nuclear envelope. During mitosis this decoration extended all over the metaphase spindle. At all stages of the cell cycle, the decoration remained specific to the micronucleus and was absent not only from all of the various cytoplasmic and cortical microtubule arrays but also from the macronuclei, even at early stages of their development from the zygotic nucleus. CTR 532 recognizes a single 170x103 Mr polypeptide in the cytoskeletal fraction that contains micronuclei and this polypeptide is absent in the cytoskeletal fraction of amicronucleate cells.
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Sangeetha, N., S. Saranyabai, Priyanka Pradeep, E. Nidhya, and Balaji Venkataraman. "Study of micronuclei as a potent biomarker in breast cytology aspirates." Panacea Journal of Medical Sciences 12, no. 3 (November 15, 2022): 651–56. http://dx.doi.org/10.18231/j.pjms.2022.121.
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: Micronuclei scoring can be used as a bio-marker of genotoxic and chromosomal damage. Fine needle aspiration cytology (FNAC) is applied as the primary tool for diagnosis in breast masses because of its ease and rapidity. Micronucleus (MN) scoring is carried out in benign (fibroadenoma) and malignant (infiltrating ductal carcinoma) breast lesions to evaluate the role of Micronuclei as a biomarker in breast carcinomas.: To study Micronuclei (MN) scores as a biomarker on breast cytology aspirated smears. This was a prospective study done for duration of two years in the Department of Pathology, A.C.S Medical College and Hospital, Chennai. The features of micronuclei in 60 breast aspirate smears were studied and compared in benign conditions, proliferative and malignant conditions.The most common diagnosis was of fibroadenoma seen in 38 (63.3%) cases. Adenosis was seen in 10 (16.6%) cases. Usual ductal hyperplasia in 6.6% cases and Invasive ductal carcinomas in 6 (10%) cases. The Average Micronucleus score/1000 cells and the range of micronucleus score was higher in malignancy as compared to benign conditions. : Micronuclei can be used as a biomarker on fine needle aspiration cytology smears of breast lesions. An increase in micronuclei is usually seen in malignant conditions as compared to benign tumours. Attention to features of micronuclei can give a clue to the presence of malignancy.
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Mammel, Anna E., Heather Z. Huang, Amanda L. Gunn, Emma Choo, and Emily M. Hatch. "Chromosome length and gene density contribute to micronuclear membrane stability." Life Science Alliance 5, no. 2 (November 17, 2021): e202101210. http://dx.doi.org/10.26508/lsa.202101210.
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Micronuclei are derived from missegregated chromosomes and frequently lose membrane integrity, leading to DNA damage, innate immune activation, and metastatic signaling. Here, we demonstrate that two characteristics of the trapped chromosome, length and gene density, are key contributors to micronuclei membrane stability and determine the timing of micronucleus rupture. We demonstrate that these results are not due to chromosome-specific differences in spindle position or initial protein recruitment during post-mitotic nuclear envelope assembly. Micronucleus size strongly correlates with lamin B1 levels and nuclear pore density in intact micronuclei, but, unexpectedly, lamin B1 levels do not completely predict nuclear lamina organization or membrane stability. Instead, small gene-dense micronuclei have decreased nuclear lamina gaps compared to large micronuclei, despite very low levels of lamin B1. Our data strongly suggest that nuclear envelope composition defects previously correlated with membrane rupture only partly explain membrane stability in micronuclei. We propose that an unknown factor linked to gene density has a separate function that inhibits the appearance of nuclear lamina gaps and delays membrane rupture until late in the cell cycle.
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Liu, Yifan, Xiaoyuan Song, Martin A. Gorovsky, and Kathleen M. Karrer. "Elimination of Foreign DNA during Somatic Differentiation in Tetrahymena thermophila Shows Position Effect and Is Dosage Dependent." Eukaryotic Cell 4, no. 2 (February 2005): 421–31. http://dx.doi.org/10.1128/ec.4.2.421-431.2005.
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ABSTRACT In the ciliate Tetrahymena thermophila, approximately 15% of the germ line micronuclear DNA sequences are eliminated during formation of the somatic macronucleus. The vast majority of the internal eliminated sequences (IESs) are repeated in the micronuclear genome, and several of them resemble transposable elements. Thus, it has been suggested that DNA elimination evolved as a means for removing invading DNAs. In the present study, bacterial neo genes introduced into the germ line micronuclei were eliminated from the somatic genome. The efficiency of elimination from two different loci increased dramatically with the copy number of the neo genes in the micronuclei. The timing of neo elimination is similar to that of endogenous IESs, and they both produce bidirectional transcripts of the eliminated element, suggesting that the deletion of neo occurred by the same mechanism as elimination of endogenous IESs. These results indicate that repetition of an element in the micronucleus enhances the efficiency of its elimination from the newly formed somatic genome of Tetrahymena thermophila. The implications of these data in relation to the function and mechanism of IES elimination are discussed.
Dissertations / Theses on the topic "Micronuclei"
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Maletska, A. V., Nataliia Oleksyivna Slyvka, and V. O. Samsonyuk. "Diagnostic value of micronuclei assay in chemical addictions." Thesis, Abstract Book. International medical science student congress. - Turkey, 13-15 may 2016, 2016. http://dspace.bsmu.edu.ua:8080/xmlui/handle/123456789/11621.
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Buchanan, Carrie C. "Micronuclei induction in AG01522 cells is independent of temperature and linear energy transfer." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44848.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2008.Includes bibliographical references (p. 42-44).
The bystander effect describes radiation-induced biological effects in nonirradiated cells that have received signals from irradiated cells. In a co-culture experiment, the bystander signaling is proposed to occur via the medium. Using a co-culture setup, the work in this thesis investigates the effects of temperature as an experimental parameter and linear energy transfer (LET) dependence on the bystander effect. Using the micronucleus assay and primary human AG01522 fibroblast cells co-cultured as both the target and bystander cells, the incidence of micronuclei in both X-ray irradiated and alpha particle irradiated bystander experiments were ~2 fold over control averages. In the temperature experiment, there were no significant differences between bystander cells co-cultured with cold (4°C) target cells and those co-cultured with warm control target cells. These results have shown, for AG01522 fibroblasts, that the bystander effect is independent of temperature and LET.
by Carrie C. Buchanan.
S.B.
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Cole, Adam. "MiNiMUS : a model to predict the formation and numbers of micronuclei in cells." Thesis, University of Surrey, 2015. http://epubs.surrey.ac.uk/807987/.
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Currently there is no in vitro testing of glioblastoma biopsy material to assess tumour sensitivity to radiation, which could form a basis for personalised treatment plans for patients. In this work, a model to predict sensitivity to radiation, via the micronucleus assay, is set out and a proof of concept is presented where numbers of micronuclei in a glioblastoma cell line, LN18 is predicted. One key requirement for the model is that any in vitro testing needs to yield results within a few days, as the timeline for glioblastoma patients from diagnosis to treatment is short. In order to achieve this, a flow cytometry technique is assessed against traditional fluorescence microscopy for detection of micronuclei. Flow cytometry was completed using an in vitro Microflow kit from Litron Laboratories. There was no previous experience using this kit in cancerous cell lines and limited experience in cell lines that adhere to their flask’s surface as the kit is used mostly in peripheral blood lymphocytes. The flow cytometry technique can be completed within the required time frame and is much less labour intensive that fluorescence microscopy. However, there is a significant amount of variance between samples which makes the microscopy results more useful for fitting the modelling work to. It is expected with further experience and use of the supplied template, as this was incompatible at the time of the experiments, will play a role in reducing some of the variance. The model, in its current state of development, is able to predict numbers of micronuclei in a cohort of cells following doses of radiation between 1 and 3 Gy. The numerical solution is based on a decision tree structure where each double strand break that would be caused by radiation is run through the tree. The tree is traversed populated using probabilities for each decision, such as the success of a repair pathway, and Monte Carlo methods for predicting the cohort response to radiation. These probabilities are fitted to experimental data. The prediction of micronuclei is the first step for the MiNiMUS model. Future work should prioritise incorporating cell death into the model and further assessing the suitability of flow cytometry for rapid micronuclei detection.
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Makowski, Mateusz. "High-Throughput Data Analysis: Application to Micronuclei Frequency and T-cell Receptor Sequencing." VCU Scholars Compass, 2015. http://scholarscompass.vcu.edu/etd/3923.
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The advent of high-throughput sequencing has brought about the creation of an unprecedented amount of research data. Analytical methodology has not been able to keep pace with the plethora of data being produced. Two assays, ImmunoSEQ and the cytokinesisblock micronucleus (CBMN), that both produce count data and have few methods available to analyze them are considered.
ImmunoSEQ is a sequencing assay that measures the beta T-cell receptor (TCR) repertoire. The ImmunoSEQ assay was used to describe the TCR repertoires of patients that have undergone hematopoietic stem cell transplantation (HSCT). Several different methods for spectratype analysis were extended to the TCR sequencing setting then applied to these data to demonstrate different ways the data set can be analyzed. The different methods include CDR3 distribution perturbation, Oligoscores, Simpson's diversity, Shannon diversity, Kullback-Liebler divergence, a non-parametric method and a proportion logit transformation method. Herein we also demonstrate adapting compositional data analysis methods to the TCR sequencing setting. The various methods were compared when analyzing a set of 13 subjects who underwent hematopoietic stem cell transplantation. The eight subjects who developed graft versus host disease were compared to the five who did not. There was no little overlap in the results of the different methods showing that researchers must choose the appropriate method for their research question of interest.
The CBMN assay measures the rate of micronuclei (MN) formation in a sample of cells and can be paired with gene expression or methylation assays to determine association between MN formation and other genetic markers. Herein we extended the generalized monotone incremental forward stagewise (GMIFS) method to the situation where the response is count data and there are more independent variables than there are samples. Our Poisson GMIFS method was compared to a popular alternative, glmpath, by using simulations and applying both to real data. Simulations showed that both methods perform similarly in accurately choosing truly significant variables. However, glmpath appears to overfit compared to our GMIFS method. Finally, when both methods were applied to two data sets GMIFS appeared to be more stable than glmpath.
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Duardo, Renee Concetta <1994>. "Unbalanced R-loops and micronuclei induced by DNA topoisomerase I poisons in cancer cells." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amsdottorato.unibo.it/10182/1/Duardo_Ren%C3%A9e_Concetta_thesis.pdf.
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Topoisomerase I (Top1) poisons are among the most clinically-effective drugs used for colon, ovary and lung cancers. Unpublished data from our lab have recently revealed that the structurally-unrelated Top1 poisons, Camptothecin (CPT) and Indimitecan (LMP776), induce the formation of micronuclei (MNi) in human cancer cells. In addition, MNi trigger an innate immune gene response by stimulating the cGAS/STING pathway. As the mechanisms of MNi formation are not fully determined, our aim is here to establish how MNi form after Top1 poisoning. Using immunofluorescence assays and EdU labelling of nascent DNAs, our results show that, after 24 hours of recovery, a short treatment with sub-cytotoxic doses of Top1 poisons induces the formation of MNi that do not contain newly synthetized (EdU+) DNA. We also saw that Top1 poisons delay replication machinery reducing EdU incorporation and produce significant levels of the damage markers γH2AX and p53BP1 in S-phase cells but not in G1 and G2/M cells. The results also show that MNi formation is dependent on R-loops, as RNaseH1 overexpression markedly reduces Top1 induced MNi. Genome-wide mapping of R-loops by DRIP-seq technique revealed that R-loop levels are both decreased and increased by CPT. In particular, increased R-loops are mainly found at active genes and always overlapped with Top1cc sites. We also found that increased R-loops overlap with lamina-associated chromatin domains while decreased R-loops correlate with replication origin sites. Overall, our data are consistent with the formation of MNi due to R-loop increase and under-replication at specific regions caused by Top1 poisons. These results will eventually help in developing new strategies for effective personalized interventions by using Top1-targeted compounds as immuno-modulators in cancer patients.
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Medvedeva, Natalia Gennadievna. "Influence of cell environment on micronucleation in Chinese hamster ovary cells." Texas A&M University, 2004. http://hdl.handle.net/1969.1/2790.
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The irradiation of cells in culture is an essential part of many radiation biology experiments. Since these experiments necessarily involve the irradiation of cell culture vessels and nutrient medium, the possibility of effects due to the interactions of irradiated material with growing cells needed to be investigated.
In the present study the micronucleus frequency in Chinese hamster ovary (CHO) cells as a function of such parameters as type of radiation, type of cell substrate, changes in cell environment, and time course of the effect were characterized. Observations of the persistence of micronucleus formation in irradiated CHO cells reveal that the number of cells containing micronuclei reaches its maximum within nine hours after irradiation and remain elevated for at least five days. The influence of the cell environment on micronucleus formation in CHO cells was examined by plating cells in preirradiated nutrient medium or on preirradiated cell culture vessels. In all experiments, pre-irradiation of the cell substrate (the culture dish or culture dish filled with medium) led to a significantly higher micronucleus frequency than when cells were plated on un-irradiated substrate. The difference is most pronounced at the lowest doses examined.
These results suggest that methods of cell culture vessel sterilization and the composition of cell attachment surfaces could be confounding factors, particularly in the experiments which are intended to examine the response of cells exposed to low doses of ionizing radiation.
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Le, Roux Jacques. "The analysis of radiation-induced micronuclei in peripheral blood lymphocytes for purpose of biological dosimetry." Master's thesis, University of Cape Town, 1995. http://hdl.handle.net/11427/27038.
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In the investigation of radiation accidents, it is of great importance to estimate the dose absorbed by exposed persons in order to plan their therapy. Although occasionally in these situations physical dose measurements are possible, most often biological methods are required for dose estimation. The aim of this investigation was to assess the suitability of the cytokinesis blocked (CB) micronucleus assay as a biodosimetric method using lymphocytes irradiated in vivo. The approach adopted to achieve this was to estimate whole body doses by relating micronuclei yields in patients undergoing radiotherapy treatment with an in vitro radiation dose-response curve. These biologically derived estimates were then compared with the corresponding doses obtained by physical measurement and calculation. As a first approach a study was performed of the in vitro dose-response of gamma-ray induced micronuclei following cytokinesis-block in the lymphocytes of peripheral blood samples obtained from 4 healthy donors. The results indicated that the distribution of the induced micronuclei were overdispersed. Furthermore, a linear dose-response relationship was established when a curve was fitted to the data by an iteratively reweighted least squares method. By means of an analysis of covariance it was demonstrated that this result is in agreement with the dose-response relationships found by various other workers (Fenech et al., 1985; Fenech et al., 1986; Fenech et al., 1989; Balasem et al., 1992, and Slabbert, 1993). To assess the suitability and accuracy of dose assessment using the CB micronucleus assay for in vivo exposure of lymphocytes, blood samples obtained from 8 patients undergoing radiotherapy before, during and after treatment were examined. The physical doses of these patients were determined according to conventional radiation treatment plans and cumulative dose-volume histograms. The dose-volume histograms permitted calculation of integral doses and subsequently the estimate of equivalent whole-body doses. The results of the CB micronucleus assay applied to peripheral blood lymphocytes of 6 patients undergoing fractionated partial-body irradiation showed a dose-related increase in micronucleus frequency in each of the patients studied. This demonstrated that micronuclei analysis may serve as a quantitative biological measure of such exposures. The pooled data of these patients compared to the pooled data of the healthy donors show that there was no statistically significant difference between in vitro and in vivo results, however a slightly lower induced micronuclei frequency was observed after in vivo exposure. When the biological dose estimates for equivalent whole-body doses obtained from the in vitro dose response curve were compared with calculated physical doses, it was found that: biologically estimated dose = 0.936 physical dose. However, there was inadequate statistical evidence to discard the hypothesis that the gradient of the equation was equal to one. Therefore, the analysis of micronuclei induced in lymphocytes in vivo yields highly quantitative information on the equivalent whole-body dose. The negative binomial method was used for analysing the micronucleus data from two patients who received single, relatively larger tumour doses of 10 Gy each, with the objective to obtain estimates of the exposed body fraction and the dose to this fraction. The dose estimates to the irradiated volume were found to be within 30% of the physical tumour dose. The irradiated volume estimates seemed to be higher than the physically calculated volumes but by discarding the correction for the loss of cells due to interphase death the agreement was good between the physically and biologically determined integral doses. This study has revealed that the CB micronucleus assay appears to offer a reliable, consistent and relatively rapid biological method of whole body dose estimation. It is recognised that further corroborative work using the techniques described in this thesis is required for estimating localized exposure.
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Ranmuthugala, Geethanjali Piyawadani, and Geetha Ranmuthugala@anu edu au. "Disinfection by-products in drinking water and genotoxic changes in urinary bladder epithelial cells." The Australian National University. National Centre for Epidemiology and Population Health, 2001. http://thesis.anu.edu.au./public/adt-ANU20011207.110344.
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There is much debate on the carcinogenic potential of disinfection by-products (DBP) in chlorinated water supplies. Until recently, epidemiological studies have been limited in their ability to examine accurately the risk of cancer with exposure to environmental carcinogens. This has largely been due to the long latency periods associated with cancer development, and the difficulties in accurately estimating chronic exposure. Although there is evidence, from predominantly case-control studies, of increased bladder cancer with exposure to chlorinated water supplies, the evidence is inconclusive.
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In an attempt to determine the carcinogenic potential of trihalomethanes (THMs) in chlorinated water, this study utilises DNA damage to bladder cells, evident as micronuclei, as a pre-clinical outcome measure. Using a pre-clinical marker helps overcome some of the limitations associated with long latency periods. The study improves on previous studies by estimating exposure to DBP at an individual level, and takes into consideration ingestion, inhalation and dermal exposure.
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A cohort study was undertaken in three Australian communities. The Bungendore (NSW) water supply was not chlorinated thereby providing a community unexposed to DBPs from chlorinated water. Canberra (ACT) and Adelaide (SA) had intermediate and relatively higher (but still within NHMRC guideline levels) of DBPs in the reticulation system. Trihalomethane levels in reticulated water (external dose) and in urine (internal dose) were used as exposure indices. As well, intake dose was computed by adjusting external dose for individual variations in ingestion and bathing. The primary outcome measure was the prevalence of micronuclei in bladder epithelial cells. A DNA index derived from flow cytometry was also used to estimate DNA damage in bladder cells. Associations between exposure and outcome were estimated using Poisson regression models, having identified and adjusted for interaction effects and confounders.
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A total of 529 participants were eligible to participate, of which 348 (65.8%) completed all aspects of the study. Analysis was limited to the 228 participants (65.53% of those who completed the study) who had slides suitable for micronuclei scoring. One hundred and forty three (63%) of the 228 participants were from the exposed communities, while 85 (37%) were from the unexposed community. This sample exceeded the estimated 50 per group required to detect a relative risk of 1.4, with a significance level of 0.05 and 80% power.
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External dose for total THM for the two chlorinated (exposed) communities ranged from 37.75 to 157.25 mg/l. Intake dose estimated by fluid intake diary ranged from 2.9 to 469.5 mg/l, while a retrospective questionnaire estimated intake dose to range from 0 to 409.4 mg/l. Internal dose (urine levels) of total THM for the same two communities ranged from 0 to 6.82 mg/l. Adjusted risk estimate for DNA damage to bladder cells (using the micronuclei assay) when total THM was assessed by available dose was 1.0002 (0.997 to 1.003), by intake dose estimated by fluid intake diary was 1.0001 (0.998 to 1.002), by intake dose estimated by questionnaire was 1.001 (0.999 to 1.003), and by internal dose was 1.05 (0.89 to 1.24). Using DNA index from flow cytometry as the outcome measure also did not identify significant associations, except when exposure was assessed as available dose of total THM (RR=1.0042; 1.0003 to 1.0081).
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The results suggest that THM levels are not significantly associated with DNA damage to bladder cell. This supports suggestions of THMs being non-genotoxic. Further work is required to assess the relationship between THM and the more mutagenic compounds, and to assess the carcinogenicity of the more mutagenic compounds at concentrations occurring in drinking water.
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GONÇALVES, Joelma Pessoa. "Avaliação da citotoxicidade e genotoxicidade de extratos orgânicos e ácido barbático isolado do líquen Cladonia salzmannii (Nyl.)." Universidade Federal de Pernambuco, 2015. https://repositorio.ufpe.br/handle/123456789/17320.
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Os metabólitos secundários dos liquens são responsáveis pela maioria das suas atividades biológicas. Muitos destes compostos apresentam relevante atividade antineoplásica. O objetivo deste trabalho foi verificar as atividades citotóxica e genotóxica in vitro dos extratos orgânicos e do ácido barbático (BAR) purificado de Cladonia salzmannii Nyl. Os extratos orgânicos foram obtidos a partir do talo liquênico (22 g) previamente limpo e seco, com os solventes éter dietílico, clorofórmio e acetona, através do método de esgotamento a quente em aparelho de Soxhlet. O ácido barbático foi purificado a partir do extrato etéreo (1,3 g). A análise química dos extratos orgânicos e do BAR purificado foi realizada através de Cromatografia em Camada Delgada (CCD). A pureza do BAR purificado foi observada através de Cromatografia Líquida de Alta Eficiência (CLAE). A atividade citotóxica dos extratos orgânicos e do BAR purificado foi determinada através do Método do MTT [brometo de 3-(4,5-dimetiltiazol-2-il)-2,5-difeniltetrazólio] e do IPBC (Índice de Proliferação com Bloqueio da Citocinese). O potencial genotóxico dos extratos orgânicos e do BAR purificado foram determinados através do teste do micronúcleo e do ensaio cometa. O dimetilsulfoxido (DMSO) foi utilizado como solvente de diluição das amostras em todos os testes de atividade biológica. Os resultados referentes a CI50 demonstraram relevante potencial citotóxico para o extrato etéreo (Ext E) (50 μg/mL) frente as linhagens celulares NCI-H292 (CI50: 29,91 μg/mL), HEp-2 (CI50: 26,75 μg/mL) e HL-60 (CI50: 3,59 μg/mL), e para o BAR purificado (25 μg/mL) contra as linhagens HEp-2 (CI50: 15,79 μg/mL) e MCF-7 (CI50: 18,28 μg/mL). Porém, a avaliação da citotoxicidade considerando o Índice de Proliferação com Bloqueio de Citocinese (IPBC) demonstrou atividade citotóxica para o BAR purificado em todas as concentrações testadas (5, 10, 20 e 40 μg/mL) e para todos os extratos orgânicos (50 μg/mL) frente as células do Carcinoma de Ehrlich. Entretanto, para o Sarcoma 180 apenas o BAR purificado na concentração de 40 μg/mL e os extratos etéreo e clorofórmico (50 μg/mL) foram considerados citotóxicos. O teste do micronúcleo (MN) demonstrou que o BAR purificado na concentração de 5 μg/mL não apresentou potencial genotóxico em ambas as linhagens celulares tumorais. Além disso, o extrato clorofórmico e BAR purificado na concentração de 10 μg/mL não foram considerados genotóxicos para o Sarcoma 180. No ensaio cometa, todos os compostos testados induziram danos ao DNA em ambas as linhagens tumorais. Com base nos resultados, considera-se que os extratos orgânicos e o BAR purificado de C. salzmannii (Nyl). apresentam atividade citotóxica e genotóxica frente as linhagens celulares tumorais testadas.
The secondary metabolites of lichens are responsible for most of their biological activities. Many of these compounds exhibit significant antineoplastic activity. The objective of this study was to evaluate the in vitro cytotoxic and genotoxic activities of organic extracts and purified barbatic acid from Cladonia salzmannii Nyl. The organic extracts were obtained from liquenic thallus (22 g) previously cleaned and dried with the solvents diethyl ether, chloroform and acetone, through hot exhausted method in a Soxhlet apparatus. The barbatic acid was purified from the ether extract (1.3 g). Chemical analysis of the organic extracts and purified BAR was performed by Thin Layer Chromatography (TLC). The purity of purified BAR was observed by High Performance Liquid Chromatography (HPLC). The cytotoxic activity of the organic extracts and purified BAR was determined by the MTT method [3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide] and IPBC (Cytokinesis-Block Proliferation Index). The genotoxic potential of the organic extracts and purified BAR was determined by the micronucleus test and comet assay. Dimethyl sulfoxide (DMSO) was used as diluting solvent of the samples in all biological tests. The results for IC50 demonstrated significant cytotoxic potential to the ether extract (Ext E) (50 μg/mL) against the cell lines NCI-H292 (IC50: 29,91 μg/mL), HEp-2 (IC50: 26,75 μg/mL) and HL-60 (IC50: 3,59 μg/mL) and to the purified BAR (25 μg/mL) against the cell lines HEp-2 (IC50: 15,79 μg/mL) and MCF-7 (IC50: 18,28 μg/mL). However, the assessment of cytotoxicity considering the Cytokinesis-Block Proliferation Index (IPBC) showed cytotoxic activity for purified BAR at all concentrations tested (5, 10, 20 and 40 μg/mL) and for all organic extracts (50 μg/mL) against Ehrlich carcinoma cells. However, for Sarcoma 180 only BAR purified at a concentration of 40 μg/mL and ether and chloroform extracts (50 μg/mL) were considered cytotoxic. The micronucleus test (MN) showed that the purified BAR at a concentration of 5 μg/mL showed no genotoxic potential in both tumor cell lines. Furthermore, the chloroform extract and purified BAR at a concentration of 10 μg/mL were not considered genotoxic for Sarcoma 180. In the comet assay, all compounds tested induced DNA damage in both tumor lines. Based on the results, it is considered that the organic extracts and the BAR purified from C. salzmannii (Nyl). exhibit cytotoxic and genotoxic activity front of the tested tumor cell lines.
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Ramirez, Andréa. "Análise de células metanucleadas de alcoólicos portadores de carcinomas orais." Universidade de São Paulo, 2000. http://www.teses.usp.br/teses/disponiveis/41/41131/tde-21022002-114235/.
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O teste do micronúcleo (MN) vem sendo utilizado omo indicador de exposição genotóxica uma vez que sua ocorrência está associada às aberrações cromossômicas. Comparou-se a frequência de MN de 30 pacientes alcoólicos crônicos portadores de carcinomas orais e orofaríngeos, nos quais o consumo de álcool variou de quatro à 59 anos, com a de 30 indivíduos abstinentes de semelhante nível sócio-econômico. A diferença (14,5 anos) entre a média da idade dos pacientes (52,9 ± 1,6) e a dos controles (38,4 ± 1,5) foi estatisticamente significante (P< 0,0001). A pesquisa consiste na análise de 2000 células de escamação da mucosa oral de três regiões distintas da boca de pacientes e controles: ao redor da lesão (B), na região contra-lateral à lesão (A) e na região fundo de saco gengivo-labial superior (C), previamente considerada controle devido à baixa incidência de tumores. As células foram fixadas, coradas e analisadas em "teste cego" através de técnica modificada e adaptada aos requisitos específicos da pesquisa. O número de MN por 2000 células por indivíduo nos pacientes, assim como nos controles mostrou uma distribuição de Poisson com dispersão assimetricamente positiva, e aumento da variância nos pacientes. A distribuição de anomalias metanucleares também exibiu desvios significantes da dispersão normal. A heterogeneidade da frequência de MN nas três regiões orais dos pacientes, avaliada através do teste de Kruskal-Wallis, mostrou-se extremamente significante (P = 0,005). Enquanto a comparação entre as regiões B vs C foi estatisticamente significante (P < 0,01), as comparações entre as regiões A vs B ou A vs C (P > 0,05) não revelaram diferenças estatisticamente significante através do teste de comparação múltipla de Dunn. As comparações das diferençasnas frequências de MN resultantes do emparelhamento entre as três regiões orais (A-B, A-C, BC), aumentou o nível de significância dos resultados quanto à heterogeneidade regional (P = 0,0003) e tornou a comparação A vs C estatisticamente significante. Entretanto, a análise da variância não paramétrica da distribuição de MN nas três regiões orais dos controles não indicou heterogeneidade (P = 0,943). As frequências de MN e de células metanucleadas nas regiões orais dos pacientes também foram comparadas à dos controles através do teste de Mann-Whitney. A diferença na região tumoral foi extremamente significante (P < 0,001) e, significante na região oposta à lesão (P = 0,03) porém não significante na região fundo de saco gengivo-labial superior (P = 0,44). Esses resultados indicam um aumento de sete vezes na frequência de MN ao redor da lesão, três vezes na região oposta à lesão e duas vezes, embora não estatisticamente significante, na região fundo de saco gengivo-labial superior, revelando um gradiente na frequência de MN no sentido C -> A -> B. Comparações das frequências de células metanucleadas: binucleadas (BI), cariorréxes (CR), cariólises (CL) e broken egg (BE) nas três regiões orais de pacientes e controles, revelaram diferenças extremamente significantes, com exceção apenas de BE, em todas as regiões orais e de CR na região fundo de saco gengivo-labial superior. As comparações dicotômicas das variáveis independentes não paramétricas com a frequência de MN através dos testes de contingência e Mann-Whitney, não foram estatisticamente significantes ao nível de 5% de probabilidade, com exceção de uma única questão do questionário de diagnóstico do alcoolismo CAGE, que confirmou o efeito do álcool. Ao contrário dos resultados esperados, as frequências de MN e anomalias metanucleares não mostraram associações significantes com a idade tanto nos pacientes como nos controles. Ainda mais, a análise de regressão múltipla escalonada da frequência de células com MN ou anomalias metanucleares sobre fatores intervenientes, como idade, fim e tempo de consumo de álcool e tempo de uso de tabaco, nos pacientes, revelou coeficientes de regressão pequenos e negativos, mas significantes. Já os coeficientes de regressão da variável CL sobre o consumo de álcool foi significantemente pequeno, mas positivo, com ou sem transformação das frequências das variáveis dependentes através da raiz quadrada. Entretanto, os resultados da análise de regressão dos pacientes, aparentemente contraditórios, podem ser explicados supondo-se que as frequências de MN, durante a exposição crônica ao álcool, teriam um forte aumento inicial, diminuindo posteriormente até um nível significantemente maior que aquele no início do consumo de álcool; por outro lado, a frequência de CL aumentaria inversamente como resultado da transformação de MN durante o processo de reparo. Pode-se deduzir a partir resultados da presente pesquisa que a análise de células com MN e anomalias metanucleares devem levar em consideração critérios de padronização citológicos rígidos. O número de células a ser contado deve ser fixo e superior a 2000 de modo que inclua a variabilidade normal (espontânea) da distribuição de MN e, ainda, eliminar viéses estatísticos na estimativa de suas frequências. Ainda, o tamanho da amostra deve ser superior à 30 indivíduos, a fim de assegurar a representatividade estatística. A significância das diferenças inter-grupais deve ser estimada através de testes não paramétricos. Além disso, análises intra-individuais (ou inter-regionais) bem como a utilização de controles específicos inter-individuais pareados quanto aos fatores intervenientes (sexo, idade, grupo étnico, nível sócio-econômico, etc.) deveriam ser práticas metodológicas usuais. Como conclusão, o teste do MN deve ser considerado como uma técnica de triagem simples, prática, econômica e não invasiva para a prevenção e monitoramento clínicos de indivíduos sob risco carcinogênico, após exposição à agentes ou situações genotóxicas, como consumo crônico e abusivo de álcool, tabaco e/ou outras drogas mutagênicas, ou ainda, manipulação profissional de derivados de petróleo e outras substâncias tóxicas industriais. No contexto da presente investigação, o teste do MN deve ser particularmente indicado para monitoramento da evolução clínica de indivíduos com tumores ou lesões leucoplásicas curadas ou removidas cirurgicamente ou após tratamentos quimo ou radioterápicos, através de comparações intra e interindividuais.Micronucleus (MN) test has been used as an indicator of genotoxic exposition since it is associated with the occurrence of chromosomal aberrations. The frequency of MN among 30 subjects with oral and oropharyngeal carcinomas, whose alcohol consumption varied from four to 59 years, was compared to that of 30 healthy control individuals, abstinent for alcohol and matched for social-economic status. Difference (14.5 years)between average age of patients (52.9 ± 1.6) and that of controls (38.4 ± 1.5) was statistically significant (P <0.0001). The investigation includes the examination of 2000 cells per individual from each of three distinct areas in the mouth of patients and controls: around the lesion (B), opposite to the lesion (A) and in the upper gengivo-labial gutter (C) taken as control site because of its low tumour occurrence. The cells were fixed, dried and analyzed under "blind test", according to the technique of Sarto, modified and fitted strictly to the requirements of the research. The number of MN per 2000 cells per individual among patients as well as controls showed a Poisson distribution with a positively asymmetric dispersion and an increased variance among patients. Distribution of metanucleated cells also departed significantly from normal dispersion. The heterogeneity of MN in the three oral regions of patients, evaluated through Kruskal-Wallis test, was highly significant (P = 0.005) and pairwise comparison B vs C was statistically significant (P < 0.01) but not comparisons between A vs B or A vs C (P > 0.05), through Dunn´s multiple comparison test. Comparisons of pairwise inter-regional oral differences of MN frequencies (A-B, A-C, B-C), increased the significance levels of the results for regional heterogeneity (P =0.0003) becoming also the comparison A vs C statistically significant. Otherwise, non parametric analysis of variance of the MN distribution in the three oral regions of the controls indicated great statistical homogeneity (P = 0.943). Frequencies of MN and metanucleated cells in the oral regions of patients were also compared to those of controls, through Mann-Whitney test. Differences were highly significant (P< 0.001) for tumoral region and significant for the region opposite to the lesion (P = 0.03) but not for the upper gengivo-labial gutter (P = 0.44). These results indicated a seven-time increase in the frequency of MN in the region around the lesion, a three-time increase in the opposite region and a two-time but non significant increase in the upper gengivo-labial gutter, revealing a gradient frequency in the way C -> A -> B. Comparisons of frequencies of metanucleated cells: binucleated (BI), cariorrhexis (CR), cariolisis (CL) and broken egg (BE) in the three oral regions, between patients and controls, showed highly significant differences, except for BE frequencies in all oral regions and for CR frequency in the upper gengivo-labial gutter. Dichotomous comparisons of non parametric independent variables, with MN frequencies, through contingency and Mann-Whitney tests, were not significant at 5% level of probability, except for CAGE diagnosis of alcoholism, which confirmed the alcohol effect. Contrary to the expected results, sistematically frequencies of MN and metanucleated cells were not significantly correlated to age among patients as well as controls. Moreover, stepwise multiple regression analysis of MN and metanucleated cells in the patients revealed small negative,but significant, regression coefficients upon intervinient factors such age, end and time of alcohol consumption and time of tobacco usage, but regression coefficients of CL, upon alcohol consumption, were significantly small, but positive, before or after square root transformation of dependent variables. However, the apparently contradictory results from analysis of regression among patients could be explained by the assumption that frequencies of MN, under alcohol exposure, had a early strong increase, but decreased, afterwards, to a level significantly greater than that before alcohol consumption, while CL frequency conversely increased significantly as a result from MN transformation, during the repair process. It could be stated from the results of the present research that examination of cells with MN and metanucleated anomalies should follow critical and strict cytological criteria of standardization. The number of cell counts should be fixed and above 2000 in order to include normal (spontaneous) variability in the distribution of MN and, therefore, to prevent biases in the estimation of its frequencies. Also, sample size should be above 30 individuals, so that the statistical representativity be assured and significance of intergroup differences, could be estimated through non parametric tests. Moreover, intra-individual (or intra-regional) examinations and specific interindividual controls matched for intervinient factors (sex, age, etnic group, socio-economic level,etc.) should be an usual methodological practice. As a conclusion, it must to be considered that MN test is a simple, practical, non-expensive and non-invasive screening technique of diagnosis for clinical prevention and management of subjects under carcinogenic risks, after exposition to genotoxical agents or situations, such as abusive and chronical consumption of alcohol, tobacco and/or other mutagenic drugs or professional manipulation of derivatives of petroleum and other toxical industrial substances. In the context of the present investigation, the MN test must particularly be indicated for monitoring the clinical evolution of subjects with healed or surgically removed tumours or leukoplasic lesions, after chemio or radiotherapic treatments, by means of intra and inter-individual cellular comparisons.
Books on the topic "Micronuclei"
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Knasmüller, Siegfried, and Michael Fenech, eds. The Micronucleus Assay in Toxicology. Cambridge: Royal Society of Chemistry, 2019. http://dx.doi.org/10.1039/9781788013604.
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Organisation for economic co-operation and development. Test No. 474: Mammalian Erythrocyte Micronucleus Test. Paris: OECD Publishing, 1997.
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Tice, Raymond R. User's guide: Micronucleus assay data management and analysis system. Las Vegas, NV: U.S. Environmental Protection Agency, Environmental Monitoring Systems Laboratory, 1990.
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Grawe, Jan. Automating the in vivo micronucleus assay in the mouse: Flow-cytometric assessment of genetic damage induced by lowlevels of ionizing radiation and by chemicals with different induction mechanisms. Uppsala: Sveriges Lantbruksuniversitet, 1993.
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Cole, Robert C. Micronucleus Assay: An Overview. Nova Science Publishers, Incorporated, 2020.
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Knasmüller, Siegfried, and Michael Fenech. Micronucleus Assay in Toxicology. Royal Society of Chemistry, The, 2019.
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Test No. 474: Mammalian Erythrocyte Micronucleus Test. OECD, 2014. http://dx.doi.org/10.1787/9789264224292-en.
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Test No. 474: Mammalian Erythrocyte Micronucleus Test. OECD, 2016. http://dx.doi.org/10.1787/9789264264762-en.
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Test No. 474: Mammalian Erythrocyte Micronucleus Test. OECD Publishing, 1997. http://dx.doi.org/10.1787/9789264071285-en.
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Test No. 487: In Vitro Mammalian Cell Micronucleus Test. OECD Publishing, 2014. http://dx.doi.org/10.1787/9789264224438-en.
Full textBook chapters on the topic "Micronuclei"
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Kato, Takamitsu A. "Cytokinesis Blocked Micronuclei Aberration Analysis." In Methods in Molecular Biology, 83–91. New York, NY: Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-2433-3_9.
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Su, Cathy, Alexis H. Haskins, and Takamitsu A. Kato. "Micronuclei Formation Analysis After Ionizing Radiation." In Radiation Cytogenetics, 23–29. New York, NY: Springer New York, 2019. http://dx.doi.org/10.1007/978-1-4939-9432-8_3.
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Al-Serori, H., M. Kundi, A. Nersesyan, F. Ferk, and S. Knasmüller. "CHAPTER 24. Electromagnetic Fields and Micronuclei." In Issues in Toxicology, 387–402. Cambridge: Royal Society of Chemistry, 2019. http://dx.doi.org/10.1039/9781788013604-00387.
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Rosin, Miriam P. "Micronuclei as Intermediate End Points in Intervention." In Advances in Experimental Medicine and Biology, 95–104. Boston, MA: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4615-3468-6_13.
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Zhang, Guang-hui, and Zhao-lin Xia. "CHAPTER 31. Petroleum, Its Derivatives and Micronuclei." In Issues in Toxicology, 514–31. Cambridge: Royal Society of Chemistry, 2019. http://dx.doi.org/10.1039/9781788013604-00514.
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Luijten, Monique N. H., Jeannie X. T. Lee, Sixun Chen, and Karen C. Crasta. "Generation of Micronuclei and Detection of Chromosome Pulverization." In Methods in Molecular Biology, 183–95. New York, NY: Springer New York, 2018. http://dx.doi.org/10.1007/978-1-4939-7780-2_12.
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Heddle, John. "CHAPTER 1. A Short Personal History of Micronuclei." In Issues in Toxicology, 1–7. Cambridge: Royal Society of Chemistry, 2019. http://dx.doi.org/10.1039/9781788013604-00001.
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Wilkins, R. C., M. A. Rodrigues, and L. A. Beaton-Green. "CHAPTER 19. Automated Identification and Scoring of Micronuclei." In Issues in Toxicology, 305–19. Cambridge: Royal Society of Chemistry, 2019. http://dx.doi.org/10.1039/9781788013604-00305.
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Rosenkranz, H. S., and G. Klopman. "Exploring Genetic and Nongenetic Relationships: The Induction of Micronuclei." In Advances in Mutagenesis Research, 46–67. Berlin, Heidelberg: Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-642-77466-9_4.
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Streffer, C., W. U. Müller, and K. Wuttke. "The Formation of Micronuclei after Exposure to Ionizing Radiation." In Chromosomal Alterations, 214–22. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-642-78887-1_22.
Full textConference papers on the topic "Micronuclei"
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Savitsky, A. A., and Y. V. Malinovskaya. "DETECTION OF MICRONUCLEI IN THE BUCCAL EPITHELIUM OF SMOKERS." In SAKHAROV READINGS 2022: ENVIRONMENTAL PROBLEMS OF THE XXI CENTURY. International Sakharov Environmental Institute of Belarusian State University, 2022. http://dx.doi.org/10.46646/sakh-2022-2-101-103.
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In this work, it was made the influence assessment on the formation of micronuclei of such factors as: smoking, smoking experience and passive smoking using the micronucleus test. The results obtained allow us to conclude that these factors affect the increase in cells with micronuclei.
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Крюков, Владимир Иванович. "MICRONUCLEI AND NUCLEAR ANOMALIES IN THE ERYTHROCYTES OF AMPHIBIANS AND REPTILES." In Перспективные научные исследования: актуальные вопросы, достижения и инновации: сборник статей международной научной конференции (СанктПетербург, Январь 2023). Crossref, 2023. http://dx.doi.org/10.58351/230110.2023.91.54.003.
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В результате спонтанного или индуцированного мутагенеза в эритроцитах периферической крови амфибий и рептилий могут возникать микроядра и морфологические аномалии ядер. Их анализ положен в основу метода исследований, названного микроядерным тестом. Использование этого теста связано с проблемой коректной морфологической дифференциации микроядер и ядерных аномалий. В данной статье рассмотрены методические вопросы типирования микроядер и ядерных аномалий ядер. В соотвествии с алгоритмом анализа ввыделены два типа микроядер: изолированные (обособленные) от клеточного ядра и примыкающие к ядру. Аномалии ядер разделены на 17 морфологических типов. Часть из них разделена на подтипы. Для каждого морфологического типа и подтипа приведены основные характеристики. Рассмотрены актуальные направления исследований частот микроядер и ядерных аномалий в эритроцитах периферической крови амфибий и рептилий. Micronuclei and nuclear morphological abnormalities can occur in the peripheral blood erythrocytes of amphibians and reptiles by a spontaneous or induced mutagenesis. The analysis of these anomalies is the basis of a research method called the micronucleus test. The use of this test is associated with problems of correct morphological differentiation of micronuclei and nuclear anomalies. This article discusses the methodological aspects of typing micronuclei and nuclear anomalies. In accordance with the analytical algorithm, two types of micronuclei are distinguished: those isolated from the cell nucleus and those adjacent to the nucleus. Nuclear anomalies are divided into 17 morphological types. Some of them are divided into subtypes. The main characteristics are given for each morphological type and subtype of anomalies. Actual problems of research on micronuclei and nuclear anomalies in amphibian and reptile erythrocytes are described in the final part of the article.
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Du, Qing, Shifang Li, Edward S. Fry, and Karl Aufderheide. "Laser tweezer manipulation of micronuclei in Paramecium." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/oam.1991.wg5.
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Optical tweezers are used in Paramecium to control the positions of nuclei that play an important role during sexual reorganization. The beam from a Nd:YAG laser (λ = 1060 nm) was directed through a beam expanding telescope, through the microscope, and onto the specimen. With a 100× planachromatic phase contrast objective, ~100 mW could be focused into a 2-3-μm spot. First, the living Paramecium was immobilized in a rotocompressor. As the result of radiation pressure at the diffraction-limited focus of the laser beam, organelles in these immobilized Paramecium could be easily trapped and manipulated. The structures that could be most easily trapped and moved were the crystals. On the other hand, with available power levels we were not able to directly trap the micro- and macronuclei because of their small relative index of refraction. However, trapped crystals could be moved virtually anywhere in the cell at the observer’s discretion, and it was demonstrated that they could be used to push the micronuclei around the cell at will. Moreover, the growth and reproduction of Paramecia that had undergone laser irradiation at our available power levels showed no deleterious effects and showed no differences with non-irradiated control specimens.
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Bian, Dakai, Jason C. Tsui, Mikhail Repin, Guy Garty, Helen Turner, Y. Lawrence Yao, and David J. Brenner. "Platform-Dependent Liquid Handling in High-Throughput Biodosimetry Tool." In ASME 2016 11th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/msec2016-8513.
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Due to the need of high speed and efficient biodosimetric assays for triage and therapy in the event of radiological or nuclear attack, a robotically-based automated biodosimetry tool (RABiT) has been developed over the past few years. Adapting the micronucleus assay from filter plates to V-shaped plates presented challenges in the liquid handling, namely cell splashing out of the V-shaped well plate during the cell harvesting, poor cell distribution on the bottom of the image plate during the dispensing, and cell loss from the image plate during the aspiration in the liquid handling process. Experimental and numerical investigations were carried out to better understand the phenomena and mitigate the problems. Surface tension and contact angle among the fluids and the plate wall were accounted for in the discrete and multiphase numerical models. Experimental conditions were optimized based on the numerical results showing the relationship between nozzle speed and amount of splashed liquid, and the relationship between aspiration speed and number of escaped cells. Using these optimized parameters, numbers of micronuclei in binucleated cells showed the same dose dependence in the RABiT-prepared samples as those in the manually prepared ones. Micronucleus assay protocol was fully realized on RABiT.
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Lintsov, Andrey, Nadezhda Pleskach, Irina Spivak, Pavel Slizhov, Sergei Shevelev, Boris Uslontsev, Vasiliy Trofimov, and Victor Mikhelson. "Analysis of micronuclei in buccal epithelial cells from asthmatic patients." In ERS International Congress 2019 abstracts. European Respiratory Society, 2019. http://dx.doi.org/10.1183/13993003.congress-2019.pa5212.
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Lozano, A. V. "Design of an Automated-Counting System of Cell Micronuclei in Micrographs." In MEDICAL PHYSICS: Eighth Mexican Symposium on Medical Physics. AIP, 2004. http://dx.doi.org/10.1063/1.1811831.
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Sousa, Debora Batista Pinheiro, Audalio Rebelo Torres, Suelen Rosana Sampaio Oliveira, Jonatas da Silva Castro, and Raimunda Nonata Fortes Carvalho Neta. "Micronuclei and erythrocytic abnormalities frequencies of freshwater fishes: Establishing a baseline for health status." In PROCEEDINGS OF THE INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2017 (ICCMSE-2017). Author(s), 2017. http://dx.doi.org/10.1063/1.5012413.
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An, Jinggang, Datian Ye, and Dandan Zhang. "Automated detection of cytokinesis-blocked micronuclei using fuzzy c-means algorithm and morphological features." In 2012 International Conference on Systems and Informatics (ICSAI). IEEE, 2012. http://dx.doi.org/10.1109/icsai.2012.6223416.
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Lloyd, Stacy M., M. Lopez, and Randa El-Zein. "Abstract LB-185: Cytokinesis-blocked micronuclei Assay (CBMN) as a biological cancer risk assessment tool." In Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL. American Association for Cancer Research, 2012. http://dx.doi.org/10.1158/1538-7445.am2012-lb-185.
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Lozano, Antonio. "Image Analysis of Cell Micronuclei Micrographs to Evaluate Their Use as Indicators of Cell Damage." In MEDICAL PHYSICS: Seventh Mexican Symposium on Medical Physics. AIP, 2003. http://dx.doi.org/10.1063/1.1615124.
Full textReports on the topic "Micronuclei"
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Tice, Raymond R., Paul Andrews, Diane Satterfield, and LeRoy Metker. Repeated Inhalation Exposure of FE-13 in Mice, Mus musculus (Bone Marrow Micronucleus Assay). Fort Belvoir, VA: Defense Technical Information Center, January 1996. http://dx.doi.org/10.21236/ada597338.
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Sadhu, Devaki. Rodent Bone Marrow Micronucleus Assay. Test Substance: Solvent Yellow 33 2-(2-Quinolyl)-1,3-indandione. Fort Belvoir, VA: Defense Technical Information Center, January 2011. http://dx.doi.org/10.21236/ada536686.
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