The use of micronucleus test for detection of genotoxic damage to the thyroid gland

Micronuclei and nuclear buds: Highlighting overlooked indicators of chromosomal damage in thyroid aspiration smears

BACKGROUND

We aimed to examine the diagnostic utility of micronuclei (MN) and nuclear buds (NBs) in aspiration smears of the well-differentiated epithelial lesions of thyroid.

METHODS

One hundred five cases composed of 34 follicular nodular disease (FND), 31 Hashimoto's thyroiditis (HT), and 40 papillary thyroid carcinoma (PTC) were compiled retrospectively. May- Grünwald Giemsa (MGG) stained smears of each case were selected to count cells with nuclear protrusions (NPs) per 1000 cells. The frequency of cells with NPs (MN&NBs) was compared by using Mann-Whitney U test and Kruskal-Wallis tests when appropriate. Post-Hoc Tukey test was used for pairwise comparison of different diagnostic categories. By running a ROC curve analysis, diagnostic usefulness of the frequency of cells with NPs (MN&NBs) and their cut-off values to predict malignant behavior were calculated. P < 0.05 was regarded as significant.

RESULTS

NPs (MN&NBs) were significantly more frequent in malignant cases than benign ones. NBs were more frequent in conventional PTC compared to FV of PTC, but the frequency of MN did not significantly differ between these. ROC curve analysis revealed that evaluation of the frequency of cells with NPs (MN&NBs) was a highly specific, sensitive, and diagnostically useful method to identify malignant behavior.

CONCLUSION

To the best of our knowledge, this is the first study in the literature to evaluate the frequency of cells with NPs (MN&NBs) in human thyroid aspiration smears. Our results show that evaluation of NPs (MN&NBs) may be a useful diagnostic tool to detect PTC in thyroid aspiration smears. Diagn. Cytopathol. 2017;45:673-680. © 2017 Wiley Periodicals, Inc.

Genotoxic effects of glyphosate or paraquat on earthworm coelomocytes

The potential genotoxicity (nuclear anomalies, damage to single-strand DNA) and pinocytic adherence activity of two (glyphosate-based and paraquat-based) commercial herbicides to earthworm coelomocytes (immune cells in the coelomic cavity) were assessed. Coelomocytes were extracted from earthworms (Pheretima peguana) exposed to concentrations Collapse

Key Words

• coelomocytes
• comet assay
• earthworm
• glyphosate
• micronucleus assay
• paraquat
• pinocytic adherence activity

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MESH Headings

• Animals
• Cell Adhesion
• Comet Assay
• DNA Damage
• Glycine/analogs & derivatives
• Glycine/toxicity
• Herbicides/toxicity
• Micronucleus Tests
• Mutagens/toxicity
• Oligochaeta/cytology
• Oligochaeta/drug effects
• Oligochaeta/genetics
• Paraquat/pharmacology
• Paraquat/toxicity
• Pinocytosis
• Toxicity Tests, Acute
• Toxicity Tests, Subacute
• Glyphosate

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Affiliation(s)

Ptumporn Muangphra Biology Department, Faculty of Science, Silpakorn University, Nakhon Pathom 73000, Thailand
Wimon Kwankua
Ravi Gooneratne

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Evaluation of an automated in vitro micronucleus assay in CHO-K1 cells

In this paper, we describe the evaluation of an automated in vitro micronucleus assay using CHO-K1 cells in 96-well plates. CHO-K1 cells were pre-loaded with a cell dye that stains the cytoplasm, after which the cells were treated with the test compounds for either 3h (for the +S9 condition) or 24h (for the -S9 condition). A total of 10 concentrations were tested, of which the top five concentrations were scored (limited by either cytotoxicity or solubility). At the end of the incubation period the cells were fixed and their DNA was stained with Hoechst. The visualization and scoring of the cells was done using an automated fluorescent microscope coupled with proprietary automated image analysis software provided by Cellomics (Pittsburg, PA). A total of 46 compounds were used in this evaluation, including 8 aneugens and 25 clastogens with varied mechanisms of action. Thirteen non-genotoxic compounds were also included. The automated scoring had a sensitivity of 88% and a specificity of 100%, with a predictive value positive of 100% and a predictive value negative of 76%, compared to data from the literature that was obtained with manual scoring. We also describe the incorporation of a metabolic activation system using rat liver S9 homogenates, and the use of cell number counts as a cytotoxicity index which is complementary to the CBPI- (cytokinesis-block proliferation index) based index. Finally, we also discuss the potential for artefactual findings due to fluorescent precipitate, which should be carefully monitored to prevent false positive results. In conclusion, the automated in vitro micronucleus scoring is a valid alternative to the manual scoring of slides, and it has the advantage of generating data in a rapid and consistent manner, and with low compound requirements, which makes it well suited as a screening assay in the early stages of compound development.