Assessment of micronucleus frequency in normal oral mucosa of patients exposed to carcinogens

Evaluation of micronuclei, cytomorphometric and cytologic changes of the oral mucosa in hookah and cigarette smokers

OBJECTIVE

To analyze the effect of hookah and cigarettes on the oral mucosa of smokers through the use of exfoliative cytology.

STUDY DESIGN

Smear samples were collected by exfoliative cytology from the tongue of 33 hookah smokers, 22 cigarette smokers, and 30 non-smokers. The selected analyses include micronuclei (MN), metanuclear anomalies, epithelial maturation, and cytomorphology (nuclear area [NA], cytoplasmic area [CA], and NA/CA ratio).

RESULTS

The largest differences observed for MN and metanuclear anomalies were between cigarette smokers and the control group (notably 1 MN P = .04; total cells with MN P = .039; total MN P = .042; karyorrhexis and binucleation, P = .0001). The hookah group, compared with the control group, showed the greatest differences for karyolysis (P = .0023), binucleation (P = .0003), and broken egg (P = .008). Significant differences were found between the smokers and the control groups regarding changes in the superficial cell without nucleus, perinuclear halo, vacuolization, color change, mucus, and keratohyalin granules. There was a significant increase in the NA and NA/CA ratio in the smoker groups.

CONCLUSION

This study showed that a combined analysis of exfoliative cytology associated with other diagnostic methods is a useful tool for studying oral carcinogenesis. Hookah and cigarettes showed similar effects in terms of displaying substantial cytogenetic and cytotoxic damage.

Assessment of cellular damage with cytome assay among environmental/occupational triazole

The use of triazole fungicides is common in Minas Gerais, Brazil. However, the risk arising from excessive and often unprotected exposure can be harmful to farmers. Therefore, we evaluated volunteers, exposed to triazole fungicides for cellular damage caused by this pesticide. In the buccal micronucleus cytome assay (BMCyt), cells were analyzed. Urinary triazoles were analyzed by the Liquid-Liquid Extraction coupled with Gas-chromatography/mass-spectrometry (LLE-GC/MS). Statistical differences were found for all cell types evaluated in residents of rural areas (n = 145). Analysis of variance showed statistical difference in kariolytic and pyknotic cells, between the groups of men and women living in rural areas, with higher incidence in the male group. Likewise, higher concentrations triazoles in urine samples in the male group were observed. Greater cellular damage suggests increases in DNA damage, chromossomal instability and cell deaths. The results showed the urgency of the public management with the implementation of measures to minimize the pesticides exposure.

Cytological Screening Model of Normal Oral Mucosa Exposed to Carcinogens: A Pilot Study

INTRODUCTION

Oral cytopathology is able to detect incipient cellular alterations, but it is not routinely applied to this purpose. We aimed to establish a model to screen individuals with no oral lesion exposed to smoking/alcohol, by means of the nuclear area, cell proliferation rate, and analysis of genetic damage.

METHODS

In this cross-sectional pilot study, 90 patients were allocated into 3 groups: oral cancer group (patients with oral squamous cell carcinoma), tobacco/alcohol group (patients without oral lesions and exposed to these risk factors), and control group (individuals with no lesion and not exposed to tobacco and alcohol). The cytological smears performed in these individuals were stained with Papanicolaou, a silver-staining and a Feulgen reaction. The nuclei of cells were measured, and AgNORs/nucleus and micronuclei (MN) were quantified. The cutoff values were stipulated evaluating the healthy mucosa (control group) and the cancerization field mucosa (oral cancer group).

RESULTS

Cutoff values for the screening of individuals exposed to carcinogens were ≥8% of nuclei larger than 100 μm2, ≥3.38 AgNOR/nucleus, and ≥3 MN per 1,000 cells.

CONCLUSIONS

Nuclear area measurement and AgNORs/nucleus and MN quantification identified the incipient phase of oral carcinogenesis. A screening model for individuals without oral lesion exposed to smoking/alcohol was proposed.

Biomonitoring of children and adolescents using orthodontic appliances made of acrylic resins through micronucleus testing of exfoliated buccal and palatal mucosa cells

INTRODUCTION

The present study aimed to investigate the occurrence of micronuclei and the degenerative nuclear alterations indicative of apoptosis and necrosis in the exfoliated buccal and palatal mucosa cells of children and adolescents using orthodontic appliances made of self-curing acrylic resins.

METHODS

The micronuclei and nuclear alterations were evaluated in a minimum of 2000 cells collected from the cheeks and palates of 30 patients of both sexes, aged between 6 and 12 years. The cell evaluations were performed before appliance installation and 15 to 21 days after installation. A conditional test was used. In all analyses, the significance level was 5%.

RESULTS

No differences in the occurrence of micronuclei or the nuclear degenerative changes indicative of apoptosis and necrosis were observed in the cheek cells between the 2 time points (P > 0.05). However, evaluation of the palate cells revealed a significant increase in the occurrence of micronuclei and the nuclear alterations indicative of apoptosis (P < 0.01) but not of karyolysis (P > 0.05).

CONCLUSIONS

Direct contact of orthodontic appliances made of acrylic resins with the oral mucosa increases the incidence of chromosomal damage and degenerative nuclear alterations.

Elevated Serum Pb, Ni, Cd, and Cr Levels and DNA Damage in Exfoliated Buccal Cells of Teenage Scavengers at a Major Electronic Waste Dumpsite in Lagos, Nigeria

This study investigated the levels of Pb, Ni, Cd, and Cr in the blood, and DNA damage in exfoliated buccal cavity of scavenging teenagers at Alaba International electronic market, Nigeria. One hundred and ninety-nine blood samples were collected from scavenging teenagers in Alaba International market (n = 95) and the control group (n = 104). Blood Pb, Ni, Cd, and Cr concentrations were analyzed using graphite furnace atomic absorption spectrometry. Genotoxicity assessment was through exfoliated buccal cell micronucleus assay, while questionnaire was used to collect data on factors that can contribute to the blood heavy metal levels. The blood Pb of scavenging teenagers from Alaba International market varied from 2.84 to 189.44 μg/L compared to the control group with a range of 0.01 to 4.21 μg/L. The blood Cd (range = 0.38-12.35 μg/L), Cr (range = 0.20-19.03 μg/L), and Ni (range = 0.24-21.01 μg/L) were higher significantly in the Alaba group compared to the control group (Cd: range = 0.00-0.96 μg/L; Cr: range = 0.01-0.72 μg/L; and Ni: range = 0.00-0.28 μg/L). Frequencies of micronucleus, karyolysis, and pycnosis in the exfoliated buccal cells in Alaba group also increased significantly compared with the control group. Spearman correlation analyses indicated a positive correlation between the blood Pb, Ni, Cd, and Cr and induced micronucleus in the buccal exfoliated cells. Furthermore, data showed a positive correlation between Pb, Ni, Cd, and Cr and the duration of scavenging of the teenagers. However, a negative correlation was observed between educational status and Pb, Ni, Cd, and Cr. E-waste indiscriminate disposal and primitive recycling processes may be responsible for the high blood heavy metal levels, and consequently an increased DNA damage in exfoliated buccal cells in scavenging teenagers at Alaba International market. Graphical Abstract.

Evaluation of genotoxic effects in Brazilian agricultural workers exposed to pesticides and cigarette smoke using machine-learning algorithms

Monitoring exposure to xenobiotics by biomarker analyses, such as a micronucleus assay, is extremely important for the precocious detection and prevention of diseases, such as oral cancer. The aim of this study was to evaluate genotoxic effects in rural workers who were exposed to cigarette smoke and/or pesticides and to identify possible classification patterns in the exposure groups. The sample included 120 participants of both sexes aged between 18 and 39, who were divided into the following four groups: control group (CG), smoking group (SG), pesticide group (PG), and smoking + pesticide group (SPG). Their oral mucosa cells were stained with Giemsa for cytogenetic analysis. The total numbers of nuclear abnormalities (CG = 27.16 ± 14.32, SG = 118.23 ± 74.78, PG = 184.23 ± 52.31, and SPG = 191.53 ± 66.94) and micronuclei (CG = 1.46 ± 1.40, SG = 12.20 ± 10.79, PG = 21.60 ± 8.24, and SPG = 20.26 ± 12.76) were higher (p < 0.05) in the three exposed groups compared to the GC. In this study, we considered several different classification algorithms (the artificial neural network, K-nearest neighbors, support vector machine, and optimum path forest). All of the algorithms displayed good classification (accuracy > 80%) when using dataset2 (without the redundant exposure type SPG). It is clear that the data form a robust pattern and that classifiers could be successfully trained on small datasets from the exposure groups. In conclusion, exposing agricultural workers to pesticides and/or tobacco had genotoxic potential, but concomitant exposure to xenobiotics did not lead to additive or potentiating effects.

Genotoxicity assessment data for exfoliated buccal cells exposed to mobile phone radiation

Healthy mobile phone users aged 18–30 y.o. provided exfoliated buccal cells samples from the right and left inner cheeks. A total of 2000 cells per subject were screened for the presence of micronuclei as a sign of genotoxic damage, according to the mobile phone use profile of each user.

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.

Cytogenetic biomonitoring of occupationally exposed workers to ashes from burning of sugar cane in Ahome, Sinaloa, México

Burning the sugar cane field before harvesting has a negative impact on both air and human health, however this issue had not been explored in Mexico. The objective of this work was to determine the chromosomal damage in workers from sugar cane burning fields in Sinaloa, México. To this purpose, we analyzed 1000 cells of buccal exfoliated epithelia from 60 exposed workers and 60 non-exposed controls to determine micronucleus frequencies and other nuclear abnormalities. The results indicated significant higher values of micronucleus and nuclear abnormalities such as binucleate cells, pyknosis, karyolysis, chromatin condensation and nuclear buds frequencies in the exposed subjects compared to those that were not exposed. Our data indicates that sugar cane burning, that generates polycyclic aromatic hydrocarbons, represents a genotoxic risk for workers in this important sugar cane producing area in Mexico.

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.

Chromosomal damage and apoptosis analysis in exfoliated oral epithelial cells from mouthwash and alcohol users

Chromosomal damage and apoptosis were analyzed in users of mouthwash and/or alcoholic beverages, using the micronucleus test on exfoliated oral mucosa cells. Samples from four groups of 20 individuals each were analyzed: three exposed groups (EG1, EG2 and EG3) and a control group (CG). EG1 comprised mouthwash users; EG2 comprised drinkers, and EG3 users of both mouthwashes and alcoholic beverages. Cell material was collected by gently scraping the insides of the cheeks. Then the cells were fixed in a methanol/acetic acid (3:1) solution and stained and counterstained, respectively, with Schiff reactive and fast green. Endpoints were computed on 2,000 cells in a blind test. Statistical analysis showed that chromosomal damage and apoptosis were significantly higher in individuals of groups EG1 and EG3 than in controls (p < 0.005 and p < 0.001, respectively). No significant difference in chromosomal damage and apoptosis was observed between the exposed groups. In EG2, only the occurrence of apoptosis was significantly higher than in the controls. These results suggest that mouthwashes alone or in association with alcoholic drinks induce genotoxic effects, manifested as chromosomal damage and apoptosis. They also suggest that alcoholic drinks are effective for stimulating the process of apoptosis. However, these data need to be confirmed in larger samples.

Alteration in buccal mucosal cells due to the effect of tobacco and alcohol by assessing the silver-stained nucleolar organiser regions and micronuclei

Background:

Oral habits such as alcohol consumption and tobacco chewing are considered to be initiators of dysplastic changes in the oral mucosa.

Aim:

The aim of this study was to determine and compare the alteration in apparently normal buccal mucosal cells due to effect of alcohol and tobacco by assessing silver-stained nucleolar organiser regions (AgNORs) and micronuclei.

Materials and Methods:

The study comprised a total of 100 subjects which were divided into four groups with 25 subjects having alcohol consuming habit, 25 subjects were tobacco consumer, 25 were both alcohol and tobacco consumer and 25 formed control group who neither consumed alcohol nor tobacco. Two cytological smears were taken from each subject with the help of cytological brush. The smear was then wet fixed and stained with AgNOR and acridine orange staining technique and assessed for nucleolar organiser region and micronuclei count respectively. 500 cells per slide were counted to note the changes.

Results:

Mann-Whitney test was applied to assess the variation in the number of AgNORs and micronuclei count between different groups. Cytological changes in each group revealed the increase in mean AgNORs and micronuclei count in subjects with combined alcohol and tobacco consumption when compared with individual groups.

Conclusions:

Tobacco and alcohol consumption produce alteration in apparently normal buccal mucosal cells, which may cumulatively lead to carcinomatous changes. Result of these changes may be used as educational tool in cessation of habits.

Cytogenetic alterations in buccal mucosa cells of chewers of areca nut and tobacco

OBJECTIVE

the rationale of the study was to evaluate the cytological alterations especially micronucleus (MN) and other nuclear anomalies in buccal mucosa cells of chewers to understand the genotoxic and clastogenic potential of chewing mixture (containing areca nut and tobacco as main ingredients).

METHODS

the buccal cytome assay involves the examination of epithelial smear to determine micronucleated cell and other nuclear anomalies after the Feulgen plus light green staining. The assay was applied to exfoliated buccal mucosa cells of 262 subjects [non-chewers - 161 and chewers - 101 (includes 20 subjects with OSMF)] and 1000 cells per individual were examined microscopically. Nuclear anomalies were compared among chewers, non-chewers and OSMF subjects and correlated with consumption of quids per day and duration of chewing in years.

RESULTS

MN cells were found significantly (p<0.0001) higher among chewers and OSMF subjects as compared to non-chewers. Further analysis indicated that MN was significantly higher in OSMF subjects with respect to even chewers. Nuclear buds were significantly higher (p<0.0001) in OSMF subjects as compared to chewers as well as non-chewers. Nuclear anomalies viz. binucleated, karyorrhexis and karyolysis were also considerably higher in OSMF subjects as compared to non-chewers.

CONCLUSION

the MN and other nuclear anomalies reflected genetic damage and cytotoxicity, associated with tobacco and areca nut consumption. Further, these data reveal a risk for development of OSMF among chewers of mixture containing areca nut and/or tobacco, as all the OSMF subjects were chewers.

Genotoxic effects of X-rays on keratinized mucosa cells during panoramic dental radiography

OBJECTIVES

The aim of this study was to evaluate the genotoxic effects of X-rays on epithelial gingival cells during panoramic dental radiography using a differentiated protocol for the micronucleus test.

METHODS

40 healthy individuals who underwent this procedure for diagnostic purposes on request from their dentists agreed to participate in this study. All of them answered a questionnaire before the examination. Epithelial gingival cells were obtained from the keratinized mucosa of the upper dental arcade by gentle scraping with a cervical brush immediately before exposure and 10 days later. Cytological preparations were stained according to the Feulgen-Rossenbeck reaction, counterstained with fast green 1% for 1 min and analysed under a light microscope. Micronuclei, nuclear projections (broken eggs) and degenerative nuclear alterations (pyknosis, karyolysis, karyorrhexis and condensed chromatin) were scored.

RESULTS

The frequency of micronuclei was significantly higher after exposure (P < 0.05), as were the frequencies of nuclear alterations indicative of apoptosis (P < 0.001).

CONCLUSIONS

These results indicate that X-ray radiation emitted during panoramic dental radiography induces a genotoxic effect on epithelial gingival cells that increases the frequency of chromosomal damage and nuclear alterations indicative of apoptosis.

Exposure to alcohol or tobacco affects the pattern of maturation in oral mucosal cells: a cytohistological study

OBJECTIVE

To assess the maturation pattern of oral mucosal cells of patients exposed to tobacco and alcohol.

METHODS

(i) Group without lesions. Smears obtained from the lower lip, border of the tongue and floor of the mouth of 31 control individuals (group I), 49 tobacco users (group II) and 27 tobacco/alcohol users (group III) were stained using the Papanicolaou method. The first 100 cells counted on each smear determined the maturation pattern and the keratinization index (KI). Analysis of variance (ANOVA) and the Tukey multiple comparison test were used for statistical analysis, at a 5% significance level. (ii) Group with lesions. Cytopathological and histopathological studies were conducted for 15 patients: eight with leucoplakia without epithelial dysplasia, two with epithelial dysplasia and five with squamous cell carcinoma.

RESULTS

(i) Group without lesions. Statistical analysis revealed a smaller number of superficial cells with nuclei in all sites of the group of tobacco/alcohol users (group III) when compared to the control group (group I), and this difference was statistically significant (P<0.005). (ii) Group with lesions. The severity of histopathological findings increased with the increase in the number of cells of the deeper epithelial layers, with a statistically significant difference in the number of intermediate (P=0.013) and parabasal cells (P=0.049), which increased with the severity of the epithelial maturation disorder: leucoplakias with dysplasia had a greater number of intermediate and parabasal cells than leucoplakias without dysplasia; and the number in squamous cell carcinomas was greater than in leucoplakias with dysplasia.

CONCLUSION

The maturation pattern of cells in the three anatomic sites showed changes that may be associated with the synergistic effect of tobacco and alcohol. Also, the severity of histopathological findings was associated with the increase in the number of cells in the deeper epithelial layers.

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

Micronuclei in exfoliated epithelial cells are widely used as biomarkers of cancer risk in humans. To elucidate the effect of different staining procedures on the outcome of such investigation, we conducted a study in which the micronuclei frequencies in oral mucosa cells of heavy smokers (n = 20) and nonsmokers (n = 10) were evaluated with nonspecific (Giemsa, May-Grünwald-Giemsa) and DNA-specific (4',6-diamidino-2-phenylindole, Feulgen, acridine orange) stains, whereas with Giemsa-based stains, the frequencies of micronuclei in smokers were significantly (4- to 5-fold) higher in the smokers group, no significant increase was observed with any of the DNA-specific stains. Furthermore, the evaluation of cells of the two study groups with Feulgen stain showed that oral mucosa cells from smokers had significantly increased levels of nuclear anomalies other than micronuclei. These anomalies are consequences of cell injury found in epithelial cells and are paralleled by formation of keratin bodies in the cytoplasm that resemble micronuclei. Correlation analyses showed that micronuclei frequencies scored in Giemsa-stained slides correlated significantly with karyorrhexis, karyolysis, condensed chromatin, and binucleates, whereas no such correlations were found with DNA-specific stains. These findings indicate that nuclear anomalies (and possibly keratin bodies) may be misinterpreted as micronuclei with nonspecific DNA stains and lead to false-positive results in studies with cells of epithelial origin. Furthermore, our results show that exposure of oral mucosa cells to genotoxic carcinogens contained in tobacco smoke does not lead to induction of micronuclei in these cells.

Nuclear changes in tongue epithelial cells following panoramic radiography

This study aimed to investigate the effect of radiation from panoramic radiographs on the cells of the lateral border of the tongue by evaluating nuclear changes. Forty-two patients were included: 22 had one radiograph (Group I), and 20 required a repeat radiograph due to error in the first exposure (Group II). Material for the cytopathologic evaluation was collected before radiographs and 10 days later. Smears were stained with the Feulgen reaction and micronuclei, buds, broken eggs, karyorrhexis and binucleate cells were scored. The comparison of nuclear changes before and after radiation exposure in both groups revealed a statistically higher number of broken eggs, buds, karyorrhexis and binucleate cells 10 days after exposure (P=0.01). The number of karyorrhexis and binucleate cells was greater in group II (P=0.01). There was no change in the frequency of micronuclei before and after the radiographs. Radiation emitted during panoramic radiographs increased the number of nuclear anomalies (except micronuclei) in exfoliated cells of the lateral border of the tongue. This effect was more pronounced when the patients were exposed to a repeat radiograph, without however implying increased risk of irreversible tissue damage.