Micronucleus evaluation of exfoliated buccal epithelial cells using liquid-based cytology preparation

Use of liquid-based cytology samples reveals genomic instability and cell death in patients undergoing orthodontic treatment

PURPOSE

To examine the use of liquid-based exfoliative cytology to determine the presence of genomic instability and cell death in the oral mucosa of patients with orthodontic appliances.

METHODS

Fifty-four oral mucosa samples were collected from 18 patients and divided into three stages: T0, before fixation of orthodontic appliances; T1, 25 days after appliance fixation; T2, 90 days after appliance fixation. All samples were Papanicolaou-stained and observed by microscopy (1,000 cells/sample) to ascertain the frequency of micronucleated cells (MN) and nuclear abnormalities (nuclear buds (NB), binucleated (BN), condensed chromatin (CC), karyorrhexis (KR), and karyolysis (KL)). Differences were analyzed statistically using the Mann-Whitney, Wilcoxon, Kruskal-Wallis and chi-squared tests.

RESULTS

After placement of orthodontic appliances, significant differences were observed for genomic instability biomarkers (MN and NB) and cell death (CC, KR and KL) (P < 0.05). Female patients and older patients exhibited a higher frequency of MN.

CONCLUSION

Liquid-based cytology has revealed that orthodontic appliances induce genomic instability and cell death in epithelial tissue of the oral mucosa, facilitating sample preservation and yielding more than one preparation per sample. Future studies should investigate whether such cell damage can be reversed through cell repair or whether cell alterations evolve and lead to disease.

Brazilian workers occupationally exposed to different toxic agents: A systematic review on DNA damage

The evaluation of genotoxicity in workers exposed to different toxic agents is very important, especially considering the association between these exposures in a chronic context and DNA damage. Assessing biomarkers of exposure and, when possible, early biomarkers of effect, contributes to elucidating the potential toxic mechanisms involved in genotoxicity and its contribution to chronic non-communicable diseases. In Brazil, the biggest country in South America, workers are exposed to hazardous physical and chemical agents. Considering that these exposures occur, in most cases, throughout the worker's whole life, this is an important public health concern in Brazil. Therefore, this systematic review aims to analyze occupational exposure to chemical and physical agents and the association with DNA damage in studies carried out in Brazil from 1980 to 2021. A systematic and comprehensive literature search was performed in different databases based on occupational exposure to chemical and physical agents and DNA damage. Only full articles on studies that investigated experimental evidence on occupational exposure in Brazil and assessed DNA damage were included, amounting to 89 articles. Five main occupational exposure groups were identified: pesticides (36%), organic solvents (20%), dust and particles (16%), metals (11%), and ionizing radiation (6%). Another group called "others" included studies (11%) that did not fall into these main groups. It was found that comet assay and micronucleus tests are the most adopted methods to detect DNA damage. Occupational exposures were most associated with DNA damage. However, further improvements in study design would be needed to better characterize the association between biomonitoring and DNA damage, particularly to account for confounding factors.

Buccal micronucleus cytome assay: Inter-laboratory scoring exercise and micronucleus and nuclear abnormalities frequencies in different populations from Brazil

The Buccal Micronucleus Cytome Assay (BMCyt) has become an important biomonitoring tool for assessing cytogenetic damage in many studied populations. Each laboratory applies protocols that vary according to the method of collecting and preparing samples. Besides, Brazil is a country of great territorial extensions that received immigrants from various parts of the world with different genetic backgrounds. Therefore, the present study aimed to evaluate the inter-laboratory variation in scoring the same set of slides using the more comprehensive scoring criteria, to standardize the BMCyt protocol, to observe the basal alterations in populations of different Brazilian regions and to compare it with other places around the world. Our results showed that a valuable number of laboratories participated, ten laboratories from different regions of the country, for the validation of the BMCyt in human biomonitoring studies, resulting in the 804 healthy individuals. This was possible because we observed: a range of measures needs to be considered, such as the baseline frequency of DNA damage and cell death in non-exposed individuals; age when grouped showed an influence on DNA damage, although when evaluated by group we did not see an influence; association between smoking habit and all endpoints of the BMCyt (except karyolytic cells) was evident; the basal MN frequency, in the majority of groups, follows those around the world; and the BMCyt was confirmed as a good health status biomarker. We emphasize the need for constant discussions on the parameters of cell death due to greater difficulty among the analyzers.

Evaluation of telomere length and genotoxicity among asphalt associated workers

There are contradictory reports about bitumen exposure and malignancy risk worldwide. Also, the evidence for genotoxicity risk among workers occupationally exposed to asphalt is insufficient. The study intended to evaluate particulate matter 10 (PM₁₀) at the workplace and biomarkers of genotoxicity effects among a group of asphalt workers in and around Bangalore, India. This study involved a total of 107 participants (54 exposed group and 53 unexposed control group). To evaluate the genotoxicity, the urinary 8-OHdG and relative telomere length as oxidative damage while micronucleus (MN) assay for cytogenetic damage was carried out during the study. The majority of workers have reported health complaints and 57.4% of them were not using any personal protective equipments (PPE's). The level of PM₁₀ detected was 104 ± 9.5 μg/m³ and 619 ± 22.7 μg/m³ in the road paving and asphalt mixing sites respectively. The biomonitoring study observed a highly significant (p = <0.001) increase in the level of 8-hydroxy-2-deoxyguanosine (8-OHdG) in the exposed group (23.17 ± 8.65 ng/mg creatinine) compared to the control (13.6 ± 7.12 ng/mg creatinine), revealed age significant associated and non-smoking borderline significant associated for oxidative stress. The relative telomere length (TL) analysis revealed its highly significant (p = 0.004) reduction in the exposed group, adjusted mean 0.95 (95% CI 0.83-1.07) compared to the control 1.06 (95% CI 0.91-1.26). The job category (p = 0.028), non-smoking (p = 0.026), and tobacco chewing (p = 0.013) were associated with reduced relative TL in the asphalt exposed group. In cytogenotoxicity analysis, the mean micronucleus (MN) frequency per 100 cells in the exposed group (26.46 ± 19.8) was significantly (p = <0.001) increased over the control group (8.56 ± 7.18). Neither smoking habit nor age appeared to influence the MN frequencies in either group. In the present study, we have demonstrated genetic damage in workers occupationally exposed to asphalt and particulate matter, raising concern for an increased risk of malignancy in these workers.

Evaluation of DNA Methylation Changes and Micronuclei in Workers Exposed to a Construction Environment

Methylation levels in tumor-suppressor genes and repetitive sequences have previously been used to study the relationship between environmental air pollution and epigenetic changes related to cancer. In this study, we measured the methylation profiles of the promoter regions CDKN2A, MLH1 and APC and the repetitive sequence LINE-1 in 59 workers exposed to the construction environment and in 49 unexposed workers. We also evaluated the micronuclei frequency and levels of trace elements in the blood of all workers. We evaluated of levels of particulate matter and polycyclic aromatic hydrocarbons (PAHs) at the construction site to characterize the environmental exposure. Our findings demonstrated that exposed workers exhibited significantly higher average levels of promoter methylation of CDKN2A, APC, and MLH1 genes and increased hypomethylation of the LINE-1 in comparison to unexposed workers (all p < 0.05). A higher frequency of micronuclei was observed in the exposed group (2 ± 2) compared to the unexposed group (1 ± 1) with p < 0.001. High levels of particulate matter (51⁻841 μg/m³) and some PAHs were found in samples from the construction environment. In summary, we provide evidence of increased DNA damage and altered DNA methylation of exposed workers, suggesting that genomic approaches to biomonitoring may be an effective way of estimating future cancer risk for construction workers.

Evaluation of Micronucleus in Exfoliated Buccal Epithelial Cells Using Liquid-based Cytology Preparation in Petrol Station Workers

Background:

Liquid-based cytology (LBC) can be used for the evaluation of micronucleus (MN) in exfoliated buccal epithelial cells of populations occupationally exposed to potentially carcinogenic agents.

Aim:

This study was undertaken to evaluate the frequency of MN of exfoliated buccal epithelial cells using LBC preparation in petrol station workers.

Materials and Methods:

Fifty petrol station workers (cases) and fifty hospital administrative staffs (controls) were recruited and evaluated for MN by May-Grunwald Giemsa, Hematoxylin and Eosin, and Papanicolaou stains using LBC preparation. Statistical analysis was performed with Student's t-test, and P < 0.05 was considered statistically significant.

Results:

Regardless of staining method used, the mean frequency of MN for cases was significantly higher than that of controls (P < 0.001).

Conclusion:

The present study concluded that petrol station workers are under risk of significant cytogenetic damage. The MN in exfoliated buccal epithelial cells found to be a useful biomarker of occupational exposure to genotoxic chemicals. LBC can be used for sample preparation to evaluate the frequency of MN in those who are occupationally exposed to potentially carcinogenic agents in view of overall improvement on sample preservation and visualization of cell morphology.

Induced cytotoxic damage by exposure to gasoline vapors: a study in Sinaloa, Mexico

Gasoline is a blend of organic compounds used in internal combustion engines. Gasoline-station attendants are exposed to gasoline vapors, which pose a potentially mutagenic risk. According to the International Agency for Research on Cancer, exposure to gasoline and engine exhaust is possibly carcinogenic to humans. We determined the frequency of micronucleus and other nuclear abnormalities, such as pyknotic nuclei, chromatin condensation, cells with nuclear buds, karyolytic cells, karyorrhexis, and binucleated cells in buccal mucosal smears of 60 gasoline-station attendants and 60 unexposed controls. In addition, we explored if factors such as smoking habits, alcohol consumption, and worked years exert an additional synergistic cytotoxic effect. There were statistically significant higher frequencies (p < 0.05) of nuclear abnormalities among exposed attendants compared to the controls. No statistical significant (p > 0.05) additional effect of lifestyle habits such as smoking and alcohol consumption or worked years on the cytotoxicity was observed. The results showed that from the beginning exposure to gasoline vapors increased the frequency of nuclear abnormalities in buccal epithelial cells. Our results provide valuable information on cytotoxic damage for an early pre-symptomatic diagnosis.

Utility of manual liquid-based cytology and conventional smears in the evaluation of various fine-needle aspiration samples

BACKGROUND

Liquid-based cytology (LBC) preparation is a way to improve and refine the fine-needle aspiration (FNA) samples. There are a few studies comparing LBC with conventional smear (CS).

AIM

The present study was undertaken to evaluate the utility of manual LBC (MLBC) and CS preparations in various FNA samples.

MATERIALS AND METHODS

In this cross-sectional study, a total of 100 FNA samples from various anatomical sites were evaluated using MLBC and CS preparations. Cellularity, blood, informative background, monolayers, cell architecture, cytoplasmic, and nuclear preservation were compared with MLBC and CS preparations by Wilcoxon signed rank test. P < 0.05 is considered statistically significant.

RESULTS

MLBC preparations were superior to CS preparations in view of absence of blood and debris (P = 0.001), presence of monolayers (P < 0.001), and preservation of cytoplasmic (P = 0.001) and nuclear details (P = 0.001). However, no statistically significant differences were found between MLBC and CS preparations with regard to cellularity (P = 0.157), informative background (P = 0.083), and architecture (P = 0.739).

CONCLUSION

MLBC preparations in FNAC are a safe, easy, and less time-consuming procedure, and it may have promising diagnostic value in the evaluation of FNA samples from various anatomical sites. However, the use of both MLBC and CS preparations is recommended to achieve optimal diagnostic yield.

Evaluation of Micronuclei, Nuclear Anomalies and the Nuclear/Cytoplasmic Ratio of Exfoliated Cervical Epithelial Cells in Genital Candidiasis

OBJECTIVE

Candida is the most common cause of fungal infections. The aim of this study was to fill the gaps in the current knowledge on the frequencies of micronuclei and nuclear anomalies, and the nucleus/cytoplasmic ratio in genital candidiasis.

STUDY DESIGN

A total of 88 Papanicolaou- stained cervical smears, which comprised Candida spp. (n = 44) and control cases with no infectious agent (n = 44), were studied. In each smear, cells with micronuclei and nuclear anomalies were counted in 1,000 epithelial cells and also nuclear and cellular areas were evaluated using image analysis software at a magnification of ×400.

RESULTS

The frequencies of micronucleated and binucleated cells and cells with perinuclear halos, and the nucleus/cytoplasmic ratio of epithelial cells were higher in the Candida-infected group compared with the control group (p < 0.05).

CONCLUSIONS

Genital candidiasis is able to induce changes in the size and shape of epithelial cells. The nuclear/cytoplasmic ratio and the frequency of micronuclei may reflect the DNA damage in the cervical epithelium. Micronucleus scoring could be used to screen the genomic damage profile of epithelial cells in candidiasis.