Effect of staining procedures on the results of micronucleus assays with exfoliated oral mucosa cells

Impact of obesity and overweight on DNA stability: Few facts and many hypotheses

Health authorities are alarmed worldwide about the increase of obesity and overweight in the last decades which lead to adverse health effects including inflammation, cancer, accelerated aging and infertility. We evaluated the state of knowledge concerning the impact of elevated body mass on genomic instability. Results of investigations with humans (39 studies) in which DNA damage was monitored in lymphocytes and sperm cells, are conflicting and probably as a consequence of heterogeneous study designs and confounding factors (e.g. uncontrolled intake of vitamins and minerals and consumption of different food types). Results of animal studies with defined diets (23 studies) are more consistent and show that excess body fat causes DNA damage in multiple organs including brain, liver, colon and testes. Different molecular mechanisms may cause genetic instability in overweight/obese individuals. ROS formation and lipid peroxidation were found in several investigations and may be caused by increased insulin, fatty acid and glucose levels or indirectly via inflammation. Also reduced DNA repair and formation of advanced glycation end products may play a role but more data are required to draw firm conclusions. Reduction of telomere lengths and hormonal imbalances are characteristic for overweight/obesity but the former effects are delayed and moderate and hormonal effects were not investigated in regard to genomic instability in obese individuals. Increased BMI values affect also the activities of drug metabolizing enzymes which activate/detoxify genotoxic carcinogens, but no studies concerning the impact of these alterations of DNA damage in obese individuals are available. Overall, the knowledge concerning the impact of increased body weight and DNA damage is poor and further research is warranted to shed light on this important issue.

Genotoxic and cytotoxic effects of Haas appliance in exfoliated buccal mucosa cells during orthodontic treatment

OBJECTIVES

To evaluate the genotoxic and cytotoxic effects of Haas appliances through micronuclei test and cytogenetic damage analysis in buccal mucosa epithelial cells of patients undergoing orthodontic treatment.

MATERIALS AND METHODS

Twenty-eight patients, 6-12 years of age and of both genders, who required a Haas appliance for the correction of a posterior crossbite were included. Epithelial cells from the mucosa were collected by gently scraping the inside of both the right and left cheeks. The cells were collected before the insertion of the appliance (T0), 1 month after the device was installed (T1), and again 3 months after the appliance was immobilized (T2). The cells were processed to obtain slides. Feulgen/Fast Green was used as the staining method, and the number of normal, karyolytic, pyknotic, nuclear buds, bi/trinucleated, and micronucleus cells were counted under light microscopy. Cellular abnormalities were evaluated with parametric and nonparametric tests for comparison of the means by analysis of variance testing, Tukey posttest, or the Kruskal-Wallis test and then by Dunn's posttest. The significance level was 5%.

RESULTS

There were no statistically significant changes in the micronuclei in the evaluated periods ( P > .05). Nuclear buds increased at T1 ( P < .05), returning to baseline levels at T2. Other abnormalities (cariolytic, pyknotic, and bi/trinucleated cells) showed a significant increase at T1 and T2 ( P < .0001).

CONCLUSIONS

The Haas appliance did not cause an increase in micronuclei in cells of the buccal mucosa. However, statistically significant increases in cariolytic, pyknotic, and bi/trinucleated cells were observed during treatment, suggesting possible DNA damage.

Impact of crack cocaine use on the occurrence of oral lesions and micronuclei

The aim of this study was to investigate the occurrence of oral lesions and micronuclei in crack cocaine users. A cross-sectional study was conducted involving 106 crack users and 106 non-users matched for age, sex, and tobacco use. Socio-demographic characteristics, the consumption of psychoactive substances, and the occurrence of fundamental lesions were investigated. Cellular changes in the oral mucosa (karyolysis, karyorrhexis, 'broken egg' events, and micronuclei) were determined by exfoliative cytology for 54 participants in each group. Crack users had a greater occurrence of fundamental lesions (P=0.001). Furthermore, they had higher mean occurrences of micronuclei (17.25 vs. 3.80), karyolysis (12.39 vs. 9.46), and karyorrhexis (30.39 vs. 10.11) (number per 1000 cells) than non-users (all P<0.05). No difference between the groups was found with regard to broken egg events (P>0.05). After controlling for confounding variables, fundamental lesions were 2.02-fold more frequent and micronuclei were 3.54-fold more frequent in crack users. Crack use was found to be associated with clinical and cellular changes in the oral mucosa. These findings can contribute to the planning of health care for individuals who are dependent on street drugs.

Comparison of Cytotoxic Effect of Cigarette and Waterpipe Smoking on Human Buccal Mucosa

Background

The evidences on cytotoxic effect of cigarette and waterpipe smoking are very rare and controversial. The aim was to compare the cytotoxic effect of cigarette and waterpipe smoking on human buccal mucosa cells.

Methods

The study was case-control. Feulgen-stained samples of exfoliated buccal mucosa cells were evaluated. The cytology slides of 25 cigarette smoker, 25 waterpipe smoker, and 25 individuals in the never smoked were examined. The number of pyknosis, karyorrhexis, and karyolysis in 1000 cells/subject were counted. Exposing to cigarette and waterpipe smoke was considered by the number of pack × years.

Results

There were significant differences among the groups in terms of karyolysis and pyknosis while there was no significant difference among the cigarette smokers group and waterpipe smokers group in terms of karyorrhexis (P ≤ 0. 01). The cytotoxicity effect of cigarette smoking was not significantly correlated to time exposure (r = 0.099, P = 0.637). The cytotoxicity effect of waterpipe smoking was significantly correlated to time exposure (r = -370, P = 0.044).

Conclusions

The cytotoxic effect of cigarette and waterpipe smoking on buccal mucosa cells was significantly higher than nonsmokers. The effect of cigarette smoking on cellular death was higher than waterpipe. The cytotoxic effect of waterpipe smoking was dose dependent.

Genotoxicity of non-alcoholic mouth rinses: A micronucleus and nuclear abnormalities study with fluorescent microscopy

AIM

The aim of the present study was to evaluate the genotoxicity of non-alcoholic mouth rinses on buccal epithelial cells using a micronucleus test.

METHODS

A total of 105 patients were selected and randomly divided into five groups. Four different mouth rinses and normal saline were given for 2 weeks' duration, and cytological smears were collected before and after exposure. These smears were subjected to micronucleus (MN) and other nuclear abnormalities (ONA) tests using acridine orange stain, and their frequencies were obtained in 500 buccal epithelial cells. The statistical analysis included mean, χ² -test, analysis of variance, and post-hoc analysis by Bonferroni test.

RESULTS

Micronucleated cells (P < .00) and MN (P < .00) were higher in individuals exposed to chlorhexidine (CHX), followed by chlorine dioxide (ClO₂ ), potassium nitrate (KNO₃ ), and sodium fluoride (NaF), amine fluoride (AmF), and normal saline. ONA were greater (P < .00) in individuals exposed to CHX, followed by ClO₂ , AmF, KNO₃ , and NaF and normal saline. Overall, the results showed that genotoxic damage was greater in the case of CHX, followed by ClO₂ , KNO₃ , and NaF, AmF, and normal saline.

CONCLUSION

Chronic exposure to mouth rinses can cause genotoxic damage to buccal epithelial cells. Long-term injudicious and inadvertent use of mouth rinses should be discouraged.

Does smoking habit increase the micronuclei frequency in the oral mucosa of adults compared to non-smokers? A systematic review and meta-analysis

OBJECTIVES

A systematic review of clinical studies to evaluate the frequency of micronuclei in the oral mucosa of smokers and non-smokers in adult patients was performed.

MATERIALS AND METHODS

A comprehensive search was carried out on MEDLINE via PubMeb, Scopus, Web of Science, LILACS, BBO, and Cochrane Library and SIGLE without restrictions. Dissertations and thesis were searched using the ProQuest Dissertations and Periodicos Capes Thesis Databases. We included only cross-sectional clinical trials that compared the frequency of micronuclei in the oral mucosa of smokers and non-smokers in adult patients.

DATA

After the removal of duplicates, 1338 articles were identified. After title and abstract screening, 35 studies remained. Eighteen studies were further excluded, whereas 17 studies remained for qualitative analysis and 16 for the meta-analysis of the primary and secondary outcomes. A significant difference in the frequency of micronuclei in smokers when compared to non-smokers was observed in the present study.

CONCLUSIONS

Despite the high variation in the methodology of the assessed studies, this study showed a higher frequency of micronuclei in exfoliated cells of smokers compared to non-smokers.

CLINICAL SIGNIFICANCE

The use of tobacco is associated with cytotoxic and genotoxic effects because a higher frequency of micronuclei in exfoliated cells of smokers was observed.

Inter-laboratory consistency and variability in the buccal micronucleus cytome assay depends on biomarker scored and laboratory experience: results from the HUMNxl international inter-laboratory scoring exercise

The buccal micronucleus cytome (BMNcyt) assay in uncultured exfoliated epithelial cells from oral mucosa is widely applied in biomonitoring human exposures to genotoxic agents and is also proposed as a suitable test for prescreening and follow-up of precancerous oral lesions. The main limitation of the assay is the large variability observed in the baseline values of micronuclei (MNi) and other nuclear anomalies mainly related to different scoring criteria. The aim of this international collaborative study, involving laboratories with different level of experience, was to evaluate the inter- and intra-laboratory variations in the BMNcyt parameters, using recently implemented guidelines, in scoring cells from the same pooled samples obtained from healthy subjects (control group) and from cancer patients undergoing radiotherapy (treated group). The results indicate that all laboratories correctly discriminated samples from the two groups by a significant increase of micronucleus (MN) and nuclear bud (NBUD) frequencies and differentiated binucleated (BN) cells, associated with the exposure to ionizing radiation. The experience of the laboratories was shown to play an important role in the identification of the different cell types and nuclear anomalies. MN frequency in differentiated mononucleated (MONO) and BN cells showed the greatest consistency among the laboratories and low variability was also detected in the frequencies of MONO and BN cells. A larger variability was observed in classifying the different cell types, indicating the subjectivity in the interpretation of some of the scoring criteria while reproducibility of the results between scoring sessions was very good. An inter-laboratory calibration exercise is strongly recommended before starting studies with BMNcyt assay involving multiple research centers.

Micronucleus Assay: An Early Diagnostic Tool to Assess Genotoxic Changes in Patients with Tobacco Use, Oral Leukoplakia and Oral Submucous Fibrosis

Introduction

Micronuclei (MNi) are acentric chromatid or chromosome fragments produced via genetic damage through genotoxic agents contained in tobacco and betel nut. Evidently, the various Oral Potentially Malignant Disorders (OPMDs) like oral lichen Planus, oral leukoplakia and Oral Submucous Fibrosis (OSMF) demonstrate MNi, as a substantiation of genetic damage. As these changes can be easily appreciated in oral exfoliated cells, an exfoliated cell based MNi assay might be utilized as handy and non invasive biomonitoring tool for gauging the genetic damage and hence the propensity for malignant transformation in OPMDs. To this end, MNi are definitely easier to evaluate when compared to chromosome aberrations.

Aim

To compare the MNi frequency in normal mucosa, in individuals using various tobacco forms without oral leukoplakia, individuals using various tobacco forms with oral leukoplakia, and areca nut chewers with OSMF, using three different stains.

Materials and Methods

Oral exfoliated cells from 50 cases of normal mucosa (Group I), 50 cases of tobacco chewing people without Oral Leukoplakia (Group II), 50 cases of people with Oral Leukoplakia (Group III) and 50 cases of areca nut chewers with OSMF (Group IV) were taken. MNi frequencies were compared in these groups using three different stains i.e., Papanicolaou (PAP) stain, May Grunwald Giemsa (MGG) stain and Feulgen stain. The data between cases (Group II, III and IV) and control groups (Group I) was analyzed by Kruskal-Wallis Test. The comparison between two independent groups was done by Mann-Whitney U test and interstain comparison between cases and control was done by Wilcoxon Signed Rank Test and the individual p-value was obtained.

Results

A significant increase in the count was observed during transition of normal mucosa to OPMDs. The best stain for detecting MNi was PAP stain followed by MGG stain and Feulgen stain.

Conclusion

The higher mean MNi count for PAP stain and MGG stain could be attributed to nonspecific staining. Further study using a larger sample size on quantitative assessment of MNi count in various OPMDs is warranted.

FBW7 Loss Promotes Chromosomal Instability and Tumorigenesis via Cyclin E1/CDK2-Mediated Phosphorylation of CENP-A

The centromere regulates proper chromosome segregation, and its dysfunction is implicated in chromosomal instability (CIN). However, relatively little is known about how centromere dysfunction occurs in cancer. Here, we define the consequences of phosphorylation by cyclin E1/CDK2 on a conserved Ser18 residue of centromere-associated protein CENP-A, an essential histone H3 variant that specifies centromere identity. Ser18 hyperphosphorylation in cells occurred upon loss of FBW7, a tumor suppressor whose inactivation leads to CIN. This event on CENP-A reduced its centromeric localization, increased CIN, and promoted anchorage-independent growth and xenograft tumor formation. Overall, our results revealed a pathway that cyclin E1/CDK2 activation coupled with FBW7 loss promotes CIN and tumor progression via CENP-A-mediated centromere dysfunction. Cancer Res; 77(18); 4881-93. ©2017 AACR.

Effect of HIV infection in the micronuclei frequency on the oral mucosa

BACKGROUND

The genotoxic impact of HIV infection on the oral cavity malignancies is unknown. The aim of this study was to evaluate the effect of HIV infection in micronucleus (MN) frequency on the oral mucosa of HIV+ patients and establish a relationship with early cytogenetic changes in oral carcinogenesis.

METHODS

Thirty HIV+ individuals who are under highly active antiretroviral therapy (HAART) and 30 non-HIV patients were evaluated. Two smears were taken from the lateral border of the tongue and mouth floor and stained by Feulgen. The frequency of MN was examined in 3000 cells per subject under common microscopy.

RESULTS

MN analysis showed no significant difference between groups by Mann-Whitney U-test for total MNs (P = 0.178). The presence of single MN was greater in control group with statistical significance (P = 0.009), while in HIV group, multiple MNs were exhibited in higher mean.

CONCLUSIONS

HIV patients under HAART therapy and low viral load values showed higher frequency of multiple MNs, which, although not statistically significant, may be caused by the action of the Vpr gene, an accessory gene of HIV. These results corroborate the theory of HIV infection cytogenetic damage.

Can Feulgen Stain be a Reliable Biomarker over PAP Stain for Estimation of Micronuclei Score?

INTRODUCTION

Malignant transformation of the Potentially Malignant Lesions (PML) in the oral cavity is associated with elevated mortality rate because of its aggressive and exceedingly invasive nature. Meticulous diagnosis and prompt therapy of PML may help prevent malignant conversion in oral lesions. Carcinogenic insult to oral cells results in chromosomal damage and formation of Micronuclei (Mn), before the development of clinical symptoms.

AIM

To determine the genotoxic effect of smoking and chewing tobacco on target tissue using Mn assay and to evaluate the prevalence of other nuclear anomalies associated with it and to determine the reliability of feulgen stain for Mn assay over Papaincolau (PAP) stain.

MATERIALS AND METHODS

PAP and feulgen staining was done to study Mn in individuals who were having tobacco habits (smoking and chewing) without lesion (n=30), individuals who were having tobacco habit (smoking and chewing) with PML (n=30) and apparently healthy subjects (n=30). Data was analysed for statistical significance using SPSS 17.0 by Kruskal - Wallis Test and Bonferronii test.

RESULTS

Tobacco habits in the form of smoking and chewing have mutagenic effects on human chromosomes which is indicated by increased frequency of Mn in oral exfoliative cells. The mean Mn frequency using feulgen stain was found to be 12.27 with lesion, 10.23 with without lesion and 3.87 in controls. Whereas, metanucleated analysis revealed no significant correlation with the formation of Mn. Non-specific DNA stain (PAP) showed high numbers of Mn cells in all the groups compared to feulgen. Statistically significant difference (p<0.0001) was observed when both the stains were compared for Mn numbers.

CONCLUSION

These findings indicate that the individuals having tobacco habits (smoking and chewing) with lesion have high number of Mn cells, thus supporting the assay to be used as a reliable biomarker to assess the genotoxic effect of tobacco in the oral mucosa. The reason for almost twice as high Mn in PAP stained smears is suggestive of cell injury which is collimated by formation of keratin bodies, resulting in its misinterpretation as Mn, leading to false positive results. Hence, it was concluded that PAP stain can be used to identify abnormal cytological changes resulting from mutagenic agent but not to interpret Mn.

Inorganic arsenic: A non-genotoxic carcinogen

Inorganic arsenic induces a variety of toxicities including cancer. The mode of action for cancer and non-cancer effects involves the metabolic generation of trivalent arsenicals and their reaction with sulfhydryl groups within critical proteins in various cell types which leads to the biological response. In epithelial cells, the response is cell death with consequent regenerative proliferation. If this continues for a long period of time, it can result in an increased risk of cancer. Arsenicals do not react with DNA. There is evidence for indirect genotoxicity in various in vitro and in vivo systems, but these involve exposures at cytotoxic concentrations and are not the basis for cancer development. The resulting markers of genotoxicity could readily be due to the cytotoxicity rather than an effect on the DNA itself. Evidence for genotoxicity in humans has involved detection of chromosomal aberrations, sister chromatid exchanges in lymphocytes and micronucleus formation in lymphocytes, buccal mucosal cells, and exfoliated urothelial cells in the urine. Numerous difficulties have been identified in the interpretation of such results, including inadequate assessment of exposure to arsenic, measurement of micronuclei, and potential confounding factors such as tobacco exposure, folate deficiency, and others. Overall, the data strongly supports a non-linear dose response for the effects of inorganic arsenic. In various in vitro and in vivo models and in human epidemiology studies there appears to be a threshold for biological responses, including cancer.

Cytological grading: An alternative to histological grading in oral squamous cell carcinoma

Background:

Micronuclei (MN) in oral exfoliative cells have been shown to indicate a disparaging change in genetic information of the cell. Recent studies showed correlation between the frequency of MN and severity of this damage. Grading of lesions can be used to determine the austerity of this damage. Aims: The aim of this study is to compare the MN frequency in oral exfoliated cells of normal and oral squamous cell carcinoma (OSCC) individuals and to cytologically grade the frequency of MN in cytological smears and to correlate it with histological grading. The objective is to ascertain whether MN frequency in oral exfoliated cells can be a parameter for grading of OSCC.

Settings and Design:

The study group comprises of 40 subjects (20 controls and 20 OSCC patients) in the age group of 45-85 years.

Materials and Methods:

The cytosmear was obtained from each group and stained with Papanicolaou (PAP) stain. Twenty cells from each slide were counted for MN and cytological grade of OSCC was assigned based on the average frequency of MN. Cytological grade was correlated with histological grading and the data were recorded. Student's t-test and Spearman's correlation were used for the analysis of the data.

Results:

Average frequency of MN was 2.5 times higher in OSCC patients when compared to that in controls and the difference was found to be highly significant. Sixty percent correlation was found between cytological grade and histological grade of OSCC and the difference between them was not significant.

Conclusions:

Cytological grading can be used in grading OSCC, and MN insinuates genotoxic damage occurring in the epithelial cells.

Pharmacological perspectives from Brazilian Salvia officinalis (Lamiaceae): antioxidant, and antitumor in mammalian cells

ABSTRACT Salvia officinalis (Lamiaceae) has been used in south of Brazil as a diary homemade, in food condiment and tea-beverage used for the treatment of several disorders. The objective of this study was to characterize chemical compounds in the hydroalcoholic (ExtHS) and aqueous (ExtAS) extract from Salvia officinalis (L.) by gas chromatography-mass spectrometry (GC-MS) and by high-resolution electrospray ionization mass spectrometry (ESI-QTOF MS/MS), evaluate in vitro ability to scavenge the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH•) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+), catalase (CAT-like) and superoxide dismutase (SOD-like) activity, moreover cytotoxic by MTT assay, alterations on cell morphology by giemsa and apoptotic-induced mechanism for annexin V/propidium iodide. Chemical identification sage extracts revealed the presence of acids and phenolic compounds. In vitro antioxidant analysis for both extracts indicated promising activities. The cytotoxic assays using tumor (Hep-2, HeLa, A-549, HT-29 and A-375) and in non-tumor (HEK-293 and MRC-5), showed selectivity for tumor cell lines. Immunocytochemistry presenting a majority of tumor cells at late stages of the apoptotic process and necrosis. Given the results presented here, Brazilian Salvia officinalis (L.) used as condiment and tea, may protect the body against some disease, in particularly those where oxidative stress is involved, like neurodegenerative disorders, inflammation and cancer.

Biomonitoring of Buccal Mucosa Cells in Chronic Smokers and Nonsmokers

Background

Despite the well-known presence of carcinogens in tobacco smoke, results in the scientific literature linking smoking habits to micronuclei frequency are rather controversial.

Aim

The study was conducted to compare and evaluate the frequency of micronuclei in chronic smokers and nonsmokers in relation to habit history, personal history, and other related factors like occupation, exposure to radiation, etc.

Materials and methods

A total of 50 randomly selected male subjects were included in the study. Case and control groups (smokers and nonsmokers respectively) comprised 25 subjects each (mean age in controls = 38.24 ± 2.7; mean age in smokers = 39.32 ± 3.8).

Results and conclusion

There was a significant relation between tobacco consumption and frequency of micronucleated cells (p = 0.05) and between radiation exposure and presence of micronuclei (p = 0.05) in controls and subjects. Within the smokers group, left cheek scrapings showed higher count (p = 0.05; significant) for the micronucleated cells as compared with right cheek scrapings.

Clinical significance

In this study, an attempt was made to estimate the cytogenetic damage in oral mucosa in people habituated to smoking beedi. Though tobacco plays an important role in micronuclei generation, other factors like ionizing radiation and personal habits also contribute to micronuclei frequency. Site of smear, sample size, nuclear specific stain usage are some of the contributing factors. In addition, cytogenetic alterations like karyolysis, pyknosis, etc., can be included in future studies to increase the specificity.

How to cite this article

Sarpal RS, Taneja N, Shergill NK, Ravindra SV. Biomonitoring of Buccal Mucosa Cells in Chronic Smokers and Nonsmokers. World J Dent 2016;7(4):189-194.

Genotoxic Evaluation of Mexican Welders Occupationally Exposed to Welding-Fumes Using the Micronucleus Test on Exfoliated Oral Mucosa Cells: A Cross-Sectional, Case-Control Study

BACKGROUND

An estimated 800,000 people worldwide are occupationally exposed to welding-fumes. Previous studies show that the exposure to such fumes is associated with damage to genetic material and increased cancer risk. In this study, we evaluate the genotoxic effect of welding-fumes using the Micronucleus Test on oral mucosa cells of Mexican welders.

MATERIAL AND METHODS

We conducted a cross-sectional, matched case-control study of n = 66 (33 exposed welders, and 33 healthy controls). Buccal mucosa smears were collected and stained with acridine orange, observed under 100x optical amplification with a fluorescence lamp, and a single-blinded observer counted the number of micronuclei and other nuclear abnormalities per 2,000 observed cells. We compared the frequencies of micronuclei and other nuclear abnormalities, and fitted generalised linear models to investigate the interactions between nuclear abnormalities and the exposure to welding-fumes, while controlling for smoking and age.

RESULTS

Binucleated cells and condensed-chromatin cells showed statistically significant differences between cases and controls. The frequency of micronuclei and the rest of nuclear abnormalities (lobed-nuclei, pyknosis, karyolysis, and karyorrhexis) did not differ significantly between the groups. After adjusting for smoking, the regression results showed that the occurrence of binucleated cells could be predicted by the exposure to welding-fumes plus the presence of tobacco consumption; for the condensed-chromatin cells, our model showed that the exposure to welding-fumes is the only reliable predictor.

CONCLUSIONS

Our findings suggest that Mexican welders who are occupationally exposed to welding-fumes have increased counts of binucleated and condensed-chromatin cells. Nevertheless, the frequencies of micronuclei and the rest of nuclear abnormalities did not differ between cases and controls. Further studies should shed more light on this subject.

Nuclear changes in oral mucosa of alcoholics and crack cocaine users

The effects of drugs of abuse on oral mucosa are only partly understood. The aims of the present study were to: (1) evaluate the frequency of nuclear changes in normal-appearing oral mucosa of alcoholics and crack cocaine users and (2) assess their association with cell proliferation rate. Oral smears were obtained from the border of the tongue and floor of the mouth of 26 crack cocaine users (24 males and 2 females), 29 alcoholics (17 males and 12 females), and 35 controls (17 males and 18 females). Histological slides were submitted to Feulgen staining to assess the frequency of micronuclei (MN), binucleated cells (BN), broken eggs (BE), and karyorrhexis (KR). A significant increase in the frequency of MN was observed in cells exfoliated from the tongue of crack cocaine users ( p = 0.01), and alcoholics showed a higher frequency of KR in cells obtained from the floor of the mouth ( p = 0.01). Our findings suggest that the use of crack cocaine induces clastogenic effects, whereas alcoholism is associated with higher degrees of keratinization in the floor of the mouth.

Evaluation of Genotoxicity and Efficacy of At-home Bleaching in Smokers: A Single-blind Controlled Clinical Trial

Objective

This single-blind controlled study evaluated the genotoxicity and efficacy of at-home bleaching in smokers and nonsmokers.

Methods

We selected 60 patients with central incisors A2 or darker: 30 smokers (experimental group) and 30 nonsmokers (control group). The bleaching was carried out with 10% carbamide peroxide for three hours a day for three weeks. The color was evaluated using a shade guide, Vita Bleachedguide 3D-Master, at baseline, during bleaching (first, second, and third weeks), and one week and one month after bleaching. Smears were obtained with a moistened wooden spatula from marginal gingiva. All the cytologic smears were stained with Giemsa solution. From each slide, 1000 cells were examined under 40× magnification and where micronuclei (MN) were located, they were examined under 100× magnification. The change in shade guide units at the different assessment periods and the frequency of MN were subjected to a two-way repeated measures analysis of variance and Tukey test (α=0.05).

Results

In both groups we detected a whitening of approximately 4 to 5 shade guide units, without color rebound after one month (p&gt;0.05). The frequency of MN was significantly higher in the experimental group than in the control group, regardless of the bleaching treatment (p&gt;0.001).

Conclusion

The efficacy of bleaching does not appear to be affected by the smoking habit. Additionally, at-home bleaching did not induce DNA damage to the gingival tissue during the bleaching period.

Assessment of hematological, biochemical effects and genotoxicity among pesticide sprayers in grape garden

Background

Many studies revealed toxic effects of pesticides on pesticide handlers but very fewer studies have been reported among grape garden pesticide sprayers in India. The purpose of this study was to evaluate the effect of pesticides among grape garden sprayers.

Methods

27 pesticide sprayers in study group and 27 non sprayers in control group were recruited. Blood samples were analyzed for hematological profile, biochemical parameters and urine samples for oxidative stress, buccal mucosal cells for genotoxicity. For statistical analysis student’s t-test and Mann Whitney U test were used.

Results

White blood cell (WBC) count was significantly decreased; uric acid and Malondialdehyde (MDA) level was significantly increased among study group. In present study the Micronucleus (MN) assay for buccal mucosal cell showed significant number of micronucleated cells in study group.

Conclusion

These results suggest that pesticide sprayers in grape garden are under risk which need to be monitored continuously in large population and further study is warranted to correlate the pesticide exposure by assessing acetylcholinesterase activity, pesticide residue analysis and their personal habits.

Frequency of micronucleus in oral epithelial cells after exposure to mate-tea in healthy humans

OBJECTIVES

The aim of this study was to evaluate the possibility of technique simplification for cytology slides in order to evaluate the frequency of micronuclei (FMic) and conduct a experiment looking to know the FMic of oral epithelial cells of healthy volunteers exposed to mate tea (Ilex paraguarariensis).

MATERIAL AND METHODS

This is a laboratorial and nonrandomized trial (quasi-experiment), where the nonusers subjects were exposed to mate-tea, consumed in the traditional way, two drinks, two times a day for a single week. Two cytology of exfoliated epithelial cells were obtained before and after the mate tea exposition.

RESULTS

The sample was composed by 10 volunteers. The age ranged from 18 to 33 years (Mean 23; SD5.5). The use of mate tea did not showed significant variation in the FMic (Wilcoxon Signed Ranks Test p= .24).

CONCLUSIONS

The proposed technique simplification showed to be reliable, without losses when compared to the conventional technique and with the advantage of eliminate toxic substances, becoming simple and practical tool for research in dentistry. The acute exposure to mate tea did not induce an increase of FMic in exfoliated buccal cells of healthy nondrinkers and nonsmokers subjects and may not have genotoxic effect. More human studies are needed before a conclusion can be made on the oral carcinogenic risk of mate tea to humans.

Potential uses, limitations, and basic procedures of micronuclei and nuclear abnormalities in buccal cells

The use of biomarkers as tools to evaluate genotoxicity is increasing recently. Methods that have been used previously to evaluate genomic instability are frequently expensive, complicated, and invasive. The micronuclei (MN) and nuclear abnormalities (NA) technique in buccal cells offers a great opportunity to evaluate in a clear and precise way the appearance of genetic damage whether it is present as a consequence of occupational or environmental risk. This technique is reliable, fast, relatively simple, cheap, and minimally invasive and causes no pain. So, it is well accepted by patients; it can also be used to assess the genotoxic effect derived from drug use or as a result of having a chronic disease. Furthermore the beneficial effects derived from changes in life style or taking additional supplements can also be evaluated. In the present paper, we aim to focus on the explanation of MN test and its usefulness as a biomarker; we further give details about procedures to perform and interpret the results of the test and review some factors that could have an influence on the results of the technique.

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

OBJECTIVE

Micronuclei (MN) are biomarkers that can be applied to buccal epithelial cells to assess populations occupationally exposed to potentially carcinogenic agents. Liquid-based cytology (LBC) is a way to improve and refine the results obtained by this test.

STUDY DESIGN

Exfoliated buccal cells were collected from 40 subjects (20 construction workers from the Barretos Cancer Hospital and 20 administrative staff from the same institution). LBC and three stains (Feulgen/fast green, Papanicolaou and Giemsa) were used to prepare the slides. Student's t test was applied for statistical comparisons of the data. A p value of <0.05 was considered statistically significant.

RESULTS

Regardless of the stain employed, the frequency of MN was greater in the case group (Feulgen/fast green: 5.15; Papanicolaou: 29; Giemsa: 26) than in the control group (Feulgen/fast green: 2.30; Papanicolaou: 17; Giemsa: 15).

CONCLUSIONS

Using LBC to prepare slides and evaluate the frequency of MN potentially serves as a screening option for more comprehensive studies of cancer risk among populations occupationally exposed to potentially carcinogenic agents. In addition, the residual fluid enables the preparation of slides for DNA-specific stains that can be compared to those with Papanicolaou stain.

A Case-Control Study of Oral Epithelial Proliferative Markers among Sudanese Toombak Dippers Using Micronuclei Assay, Argyrophilic Nucleolar Organizer Region, Papanicolaou and Crystal Violet Methods

The use of Toombak has been reported to play a major role in the etiology of oral cancer in Sudan. The cellular proliferative activity on the oral epithelium of 210 Toombak dippers was assessed by applying the micronuclei frequency, mean argyrophilic nucleolar organizer region (AgNOR) counts, Papanicolaou method, and 1% crystal violet stain. Participants were divided into 3 groups: 200 were apparently healthy individuals, 100 were Toombak users (cases), 100 were non-tobacco users (control) and 10 were patients with oral squamous cell carcinomas. Cytological atypia was identified among 4 (4%). Toombak users and was not found among the control group (P<0.04). The micronuclei frequencies were higher in Toombak users (1.026) than in the control group (0.356) (P<0.0001). The mean AgNOR counts in Toombak users (2.423) were higher than control group (1.303) (P<0.0001). Neither Toombak users nor control group showed mitotic figures in 1% crystal violet method. The results of this research showed that Toombak dipping is a high risk factor for increase in the cellular proliferation in the oral mucosa. The cytological proliferative marker methods used are useful for screening Toombak users.

Characterization of intracellular inclusions in the urothelium of mice exposed to inorganic arsenic

Inorganic arsenic (iAs) is a known human carcinogen at high exposures, increasing the incidences of urinary bladder, skin, and lung cancers. In most mammalian species, ingested iAs is excreted mainly through urine primarily as dimethylarsinic acid (DMA(V)). In wild-type (WT) mice, iAs, DMA(V), and dimethylarsinous acid (DMA(III)) exposures induce formation of intramitochondrial urothelial inclusions. Arsenite (iAs(III)) also induced intranuclear inclusions in arsenic (+3 oxidation state) methyltransferase knockout (As3mt KO) mice. The arsenic-induced formation of inclusions in the mouse urothelium was dose and time dependent. The inclusions do not occur in iAs-treated rats and do not appear to be related to arsenic-induced urothelial cytotoxicity. Similar inclusions in exfoliated urothelial cells from humans exposed to iAs have been incorrectly identified as micronuclei. We have characterized the urothelial inclusions using transmission electron microscopy (TEM), DNA-specific 4',6-diamidino-2-phenylindole (DAPI), and non-DNA-specific Giemsa staining and determined the arsenical content. The mouse inclusions stained with Giemsa but not with the DAPI stain. Analysis of urothelial mitochondrial- and nuclear-enriched fractions isolated from WT (C57BL/6) and As3mt KO mice exposed to arsenate (iAs(V)) for 4 weeks showed higher levels of iAs(V) in the treated groups. iAs(III) was the major arsenical present in the enriched nuclear fraction from iAs(V)-treated As3mt KO mice. In conclusion, the urothelial cell inclusions induced by arsenicals appear to serve as a detoxifying sequestration mechanism similar to other metals, and they do not represent micronuclei.

The HUMNxl scoring criteria for different cell types and nuclear anomalies in the buccal micronucleus cytome assay - an update and expanded photogallery

The buccal micronucleus cytome assay is a minimally invasive cytological and interphase cytogenetic technique for measuring DNA damage and cell death biomarkers in the oral epithelium. In this report we provide an updated and more comprehensive version of the cellular and nuclear scoring criteria used in the assay accompanied with a photogallery of the various cell types and nuclear anomalies. These detailed scoring criteria complement previous published protocols of this assay and form the basis for guiding intra- and inter-laboratory slide scoring comparisons. The scoring criteria update described in this paper is the outcome of ongoing efforts of the HUMN and HUMNxl projects (www.humn.org) to standardize the application of micronucleus assay for use in human biomonitoring and to update procedures as knowledge on mechanisms and technical capability improvements.

Urothelial cell intracytoplasmic inclusions after treatment of promyelocytic leukemia with arsenic trioxide

Intramitochondrial inclusions containing arsenite that occur within urothelial cells have been previously described in mice exposed to high concentrations of arsenic but not in rats. In epidemiology studies, similar urothelial cell inclusions have also been observed in the urine of humans exposed to high concentrations of arsenic in the drinking water; however, these inclusions were mistakenly identified as micronuclei. To further examine the urothelial cell inclusions that occur in inorganic arsenic-exposed humans, we evaluated two patients with a history of acute promyelocytic leukemia treated for disease relapse with a combination of all-trans retinoic acid and arsenic trioxide. Posttreatment examination of the patients' urine cytology specimens by light and electron microscopy demonstrated cytoplasmic inclusions in exfoliated superficial urothelial cells similar to those seen in mice. The inclusions were present in decreasing quantities at 3 and 7 months after completion of treatment. No comparable inclusions were detected in exfoliated urothelial cells in urine from six individuals not treated with arsenic trioxide. Based on the results of the examination by light and electron microscopy, we have determined that urothelial cell inclusions in the urine of humans previously identified as micronuclei are instead intracytoplasmic inclusions similar to those found in arsenic-treated mice.

Bio-monitoring for the genotoxic assessment in road construction workers as determined by the buccal micronucleus cytome assay

Buccal micronucleus cytome (BMCyt) assay monitors genetic damage, cell proliferation and cell death in humans exposed to occupational and environmental agents. BMCyt is used as an indicator of genotoxic exposure, since it is associated with chromosomal instability. There is little research on the occupational exposure among road construction workers for genotoxicity testing. In the present study, we evaluated MN frequencies and other nuclear changes, karyorrhexis (KR), karyolysis (KL), broken egg (BE), binucleate (BN), condensed chromatin cell (CCC), and picnotic cell (PC) in buccal mucosa cells of 40 road construction workers (twenty smokers and twenty non-smokers) and 40 control groups consisting of healthy persons (twenty smokers and twenty non-smokers). Microscopic observation was performed of 2000 cells per individual in both road construction workers and control group. In control and worker groups, for each person repair index (RI) was calculated via formula KR+L/BE+MN. The results showed a statistically significant increase in the frequency of MN in buccal epithelial cells of exposed group compared with control group (p<0.001). There is no significant difference between smokers and non-smokers for incidence of MN or nuclear changes and value of RI in exposed group. In road construction workers, RI is lower than the control group. There is a significant difference between workers and control group (p<0.001) for RI. Our data reveal that asphalt fumes during road paving operations are absorbed by workers and that asphalt fume exposure is able to significantly induce cytogenetic damage in buccal mucosa cells of workers after controlling some possible confounding factors, such as age, sex and smoking habits. In addition to determination of nuclear changes and the micronucleus, the determination of RI value presents a new approach to genotoxic bio-monitoring assessment studies of occupationally exposed population.

A comparative study for selectivity of micronuclei in oral exfoliated epithelial cells

BACKGROUND

Micronucleus (MN) represents small, additional nuclei formed by the exclusion of chromosome fragments or whole chromosomes lagging at mitosis. MN rates, therefore, indirectly reflect chromosome breakage or impairment of the mitotic apparatus. During the last few decades, micronuclei ("MNi") in oral exfoliated epithelial cells are widely used as biomarkers of chromosomal damage, genome instability and cancer risk in humans. However, until now only little attention has been given to the effect of different staining procedures on the results of these MN assays.

AIM

To compare the MNi frequencies in oral exfoliated epithelial cells using three different stains, i.e.,Feulgen stain, Papanicolaou stain (Pap) and hemotoxylin and eosin stain (H and E).

MATERIALS AND METHODS

Oral exfoliated cells from 45 cases of potentially malignant disorders (15 oral submucous fibrosis, 15 lichen planus and 15 leukoplakia) and 15 controls with healthy mucosa, were taken and MNi frequencies (No. of MNi/1000 cells) were compared using three different stains.

RESULTS

Mean MNi frequency in cases was found to be 3.8 with Feulgen stain, 16.8 with PAP and 25.9 with H and E. In controls, mean MNi frequency was 1.6 with Feulgen stain, 7.7 with PAP and 9.6 with H and E stain. Statistically significant value (P < 0.01) were observed when the three stains were compared together using Kruskal Walli's ANOVA test.

CONCLUSION

Feulgen being a DNA-specific stain gave the least counts, although statistically significant results from the comparison of MNi frequency between cases and controls were obtained with all the three stains.

Micronucleus assay in human cells: lymphocytes and buccal cells

The micronucleus (MN) assay, applied in different surrogate tissues, is one of the best validated cytogenetic techniques for evaluating chromosomal damage in humans. The cytokinesis-block micronucleus cytome assay (CBMNcyt) in peripheral blood lymphocytes is the most frequent method in biomonitoring human populations to evaluate exposure to genotoxic agents, micronutrient deficiency, or excess and genetic instability. Furthermore recent scientific evidence suggests an association between an increased MN frequency in lymphocytes and risk of cancer and other age-related degenerative diseases. The micronucleus cytome assay applied in buccal exfoliated cells (BMNCyt) provides a complementary method for measuring DNA damage and cytotoxic effects in an easily accessible tissue not requiring in vitro culture. The protocol for CBMNcyt described here refers to the use of ex vivo whole blood involving 72 h of culture with the block of cytokinesis at 44 h. BMNCyt protocol reports the established method for sample processing, slide preparation, and scoring.

Cancer cell micronucleus: an update on clinical and diagnostic applications

Micronucleus (MN) is the small nucleus that forms whenever a chromosome or its fragment is not incorporated into one of the daughter nuclei during cell division. Any form of genotoxic stress due to extraneous or internal factors leads to formation of a MN, which serves as an indicator of chromosomal instability. Chromosomal damage and formation of MN are believed to play a significant role in the pathogenesis of many malignancies. Studies have shown that MN assay can be used as a tool for risk prediction, screening, diagnosis, prognosis and as a treatment-response indicator in cancers. With the advancements in technology, greater details are becoming available regarding the molecular events in carcinogenesis. The micronuclei (MNi) in the cancer cells are now being used as tools to understand the pathogenetics of the malignancies. However, despite large number of studies on MNi in lymphocytes or exfoliated cells of cancer patients, the data regarding a cancer cell MN remain scarce. This review article tries to unleash some of the mysteries related to the formation of MN inside the cancer cell. Also, it discusses the possible effects and the events post MN formation in the cancer cell.

Aqueous extracts of Lentinula edodes and Pleurotus sajor-caju exhibit high antioxidant capability and promising in vitro antitumor activity

Mushroom extracts are increasingly sold as dietary supplements because of several of their properties, including the enhancement of immune function and antitumor activity. We hypothesized that soluble polar substances present in mushroom extracts may show antioxidant and anticancer properties. This report shows that Brazilian aqueous extracts of Lentinula edodes and Pleurotus sajor-caju exert inhibitory activity against the proliferation of the human tumor cell lines laryngeal carcinoma (Hep-2) and cervical adenocarcinoma (HeLa). Cell viability was determined after using 3 different temperatures (4°C, 22°C, and 50°C) for mushroom extraction. Biochemical assays carried out in parallel indicated higher amounts of polyphenols in the L edodes extracts at all extraction temperatures investigated. The scavenging ability of the 2,2-diphenyl-1-picrylhydrazyl radical showed higher activity for L edodes extracts. Superoxide dismutase-like activity showed no statistically significant difference among the groups for the 2 tested extracts, and catalase-like activity was increased with the L edodes extracts at 4°C. The results for the cytotoxic activity from P sajor-caju extracts at 22°C revealed the half maximal inhibitory concentration values of 0.64% ± 0.02% for Hep-2 and 0.25% ± 0.02% for HeLa. A higher cytotoxic activity was found for the L edodes extract at 22°C, with half maximal inhibitory concentration values of 0.78% ± 0.02% for Hep-2 and 0.57% ± 0.01% for HeLa. Substantial morphological modifications in cells were confirmed by Giemsa staining after treatment with either extract, suggesting inhibition of proliferation and induction of apoptosis with increasing extract concentrations. These results indicate that the aqueous extracts of Brazilian L edodes and P sajor-caju mushrooms are potential sources of antioxidant and anticancer compounds. However, further investigations are needed to exploit their valuable therapeutic uses and to elucidate their modes of action.

Effects of unconjugated bilirubin on chromosomal damage in individuals with Gilbert's syndrome measured with the micronucleus cytome assay

Circulating unconjugated bilirubin (UCB) has been reported to protect against lung and colorectal cancer. The present study aimed to explore, for the first time, whether mildly elevated circulating UCB, as found in Gilbert`s syndrome (GS), is associated with changes of DNA damage. A random 76 individuals, matched for age and gender, were recruited from the general population and allocated into the GS group (UCB ≥ 17.1 µM; n = 38) or control group (UCB <17.1 µM; n = 38). Chromosomal and cytological changes were determined in lymphocytes and buccal cells using the cytokinesis-block micronucleus cytome assay (CBMN) and buccal micronucleus cytome assay (BMcyt). No significant differences were found between GS subjects and the control group in the CBMN and BMcyt determined endpoints. Subsequently, when age dependency of effects were analysed, lower formation of buccal micronucleated cells (by 73.3%) and buccal nuclear buds (by 70.9%) in the GS subgroup ≥ 30 years were found, compared to the GS subgroup <30 years. These findings suggest DNA protection in epithelial tissue of older individuals with GS.

Re-evaluation of a reported increased micronucleus frequency in lymphocytes of workers occupationally exposed to formaldehyde

A replicate evaluation of increased micronucleus (MN) frequencies in peripheral lymphocytes of workers occupationally exposed to formaldehyde (FA) was undertaken to verify the observed effect and to determine scoring variability. May-Grünwald-Giemsa-stained slides were obtained from a previously performed cytokinesis-block micronucleus test (CBMNT) with 56 workers in anatomy and pathology laboratories and 85 controls. The first evaluation by one scorer (scorer 1) had led to a highly significant difference between workers and controls (3.96 vs 0.81 MN per 1000 cells). The slides were coded before re-evaluation and the code was broken after the complete re-evaluation of the study. A total of 1000 binucleated cells (BNC) were analysed per subject and the frequency of MN (in ‰) was determined. Slides were distributed equally and randomly between two scorers, so that the scorers had no knowledge of the exposure status. Scorer 2 (32 exposed, 36 controls) measured increased MN frequencies in exposed workers (9.88 vs 6.81). Statistical analysis with the two-sample Wilcoxon test indicated that this difference was not significant (p=0.17). Scorer 3 (20 exposed, 46 controls) obtained a similar result, but slightly higher values for the comparison of exposed and controls (19.0 vs 12.89; p=0.089). Combining the results of the two scorers (13.38 vs 10.22), a significant difference between exposed and controls (p=0.028) was obtained when the stratified Wilcoxon test with the scorers as strata was applied. Interestingly, the re-evaluation of the slides led to clearly higher MN frequencies for exposed and controls compared with the first evaluation. Bland-Altman plots indicated that the agreement between the measurements of the different scorers was very poor, as shown by mean differences of 5.9 between scorer 1 and scorer 2 and 13.0 between scorer 1 and scorer 3. Calculation of the intra-class correlation coefficient (ICC) revealed that all scorer comparisons in this study were far from acceptable for the reliability of this assay. Possible implications for the use of the CBMNT in human biomonitoring studies are discussed.