Micronucleus Formation Research Articles

Palmitoyl ascorbic acid glucoside enhanced cell survival with post irradiation treatment

Radiation exposure poses a significant threat to cellular integrity by inducing DNA damage through the generation of free radicals and reactive oxygen species. Ascorbic acid, particularly its derivative Palmitoyl Ascorbic Acid 2-Glucoside (PA2G), has demonstrated remarkable radioprotective properties. While previous research focused on its pre-irradiation application, this study explores the post-irradiation radiomitigation potential of PA2G. Our findings reveal that post-irradiation treatment with PA2G enhances cell survival and accelerates DNA repair processes, particularly the non-homologous end-joining (NHEJ) repair pathway. Notably, PA2G treatment reduces the frequency of lethal chromosomal aberrations and micronuclei formation, indicating its ability to enhance the repair of complex DNA lesions. Furthermore, PA2G is shown to play a role in potentially lethal damage repair (PLDR). These radioprotective effects are specific to NHEJ and ATM pathways, as cells deficient in these mechanisms do not benefit from PA2G treatment. This study highlights PA2G as a versatile radioprotector, both pre- and post-irradiation, with significant potential for applications in radiation therapy and protection, offering new insights into its mechanism of action. Further research is required to elucidate the precise molecular mechanisms underlying PA2G's radiomitigation effects and its potential clinical applications.

Non-regulated haloaromatic water disinfection byproducts act as endocrine and lipid disrupters in human placental cells

The disinfection of drinking water generates hundreds of disinfection byproducts (DBPs), including haloaromatic DBPs. These haloaromatic DBPs are suspected to be more toxic than haloaliphatic ones, and they are currently not regulated. This work investigates their toxicity and ability to interfere with estrogen synthesis in human placental JEG-3 cells, and their genotoxic potential in human alveolar A549 cells. Among the haloaromatic DBPs studied, halobenzoquinones (2,6-dichloro-1,4-benzoquinone (DCBQ) and 2,6-dibromo-1,4-benzoquinone (DBBQ)) showed the highest cytotoxicity (EC50: 18–26 μg/mL). They induced the generation of very high levels of reactive oxygen species (ROS) and up-regulated the expression of genes involved in estrogen synthesis (cyp19a1, hsd17b1). Increased ROS was linked to significant depletion of polyunsaturated lipid species from inner cell membranes. The other DBPs tested showed low or no significant cytotoxicity (EC50 ≥ 100 μg/mL), while 2,4,6-trichloro-phenol (TCP), 2,4,6-tribromo-phenol (TBP) and 3,5-dibromo-4-hydroxybenzaldehyde (DCHB) induced the formation of micronuclei at concentrations much higher than those typically found in water (100 μg/mL). This study reveals the different modes of action of haloaromatic DBPs, and highlights the toxic potential of halobenzoquinones, which had a significant impact on the expression of placenta steroid metabolism related genes and induce oxidative stress, implying potential adverse health effects.

Genotoxicity and the stability of N-nitrosomorpholine activity following UVA irradiation

This study investigated N-nitrosomorpholine (NMOR) genotoxicity following UVA irradiation without metabolic activation. Following UVA irradiation, the photo treated NMOR (irradiated NMOR) was directly mutagenic, without UVA or metabolic activation, in the Ames test. The activity was relatively stable, and approximately 79% of the activity remained after 10 days of storage at 37 °C, 4 °C, or −20 °C. Micronuclei (MN) formation was observed in HaCaT cells after treatment with irradiated NMOR without metabolic activation. The action spectrum of MN formation in response to NMOR irradiation followed the NMOR absorption curve. In vivo, MN formation was observed in the peripheral blood reticulocytes of mice injected with irradiated NMOR under the inhibition of cytochrome P450-mediated metabolism of NMOR. Volatile NMOR may attach to environmental materials and be irradiated with environmental UVA light. Photoactivated NMOR-attached air pollutants could float in the air and fall onto the human body, leading to genotoxicity induced by the irradiated NMOR.

Abstract B069: Targeting vulnerabilities in double strand break repair in cancer with polymerase theta inhibitors

Abstract Mutations in isocitrate dehydrogenase 1 and 2 (IDH1/2) occur in approximately 80% of secondary glioblastomas and low-grade gliomas and to a lesser extent in AML, cholangiocarcinoma, colorectal cancer, and chondrosarcomas. Mutations in IDH1/2 lead to the overproduction of 2-hydroxyglutarate (2HG), which has been named an “oncometabolite” and is implicated in cancer progression. Work by our group has shown that 2HG induced hypermethylation suppresses homologous recombination repair. As a result, cells with mutations in IDH1/2 accumulate double strand breaks (DSBs) that must be addressed by other modes of DSB repair, such as canonical NHEJ or polymerase theta mediated end joining (TMEJ). Furthermore, TMEJ is understudied in IDH1/2-mutant cancers but has been studied extensively in other HR-deficient cancer contexts, such as BRCA-mutant cancers. Conflicting reports remain on whether TMEJ promotes genomic stability or instability in these contexts, due to its error prone repair. To better understand how IDH1/2-mutant cells utilize TMEJ and polymerase theta’s impact on genomic stability, we studied the effects of polymerase theta inhibitors on isogenic cell line models of the IDH1R132H mutation. We find that mRNA levels of polymerase theta are increased in IDH1-mutant cell lines. Using a polymerase theta inhibitor, ART558, we also observed reduced viability in IDH1-mutant cells compared to parental cells. This loss of viability in IDH1-mutant cells is likely a result of the observed increase of gamma H2AX subnuclear foci in IDH1-mutant cells treated with ART558, which is a marker of unresolved DNA damage. Preliminary data suggests that this unrepaired damage is contributing to an overall increase in micronuclei formation in IDH1-mutant cells treated with ART558 as well. Taken together, these results suggest that IDH1-mutant cells upregulate polymerase theta expression to promote genomic stability through repair of persistent DSBs. This study on TMEJ in IDH1/2 mutant cancers has identified a therapeutic vulnerability in these HR-deficient cancers that can be targeted with polymerase theta inhibitors. Citation Format: Katelyn Noronha, Samantha Liu, Karlie Lucas, Ranjit S. Bindra. Targeting vulnerabilities in double strand break repair in cancer with polymerase theta inhibitors [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B069.

Genome size and DNA endoreplication pattern of non-generative cells in the antheridia of Chara connivens Salzmann ex A. Braun from Northern Morocco

Data on nuclei, mitotic divisions, chromosomal behaviors, and DNA measurements have been examined in individuals of Chara connivens collected in a pond from the Tangier-Tetouan Region (Northern Morocco). Image Cytometry of individual nuclei was used to examine the endoreduplication level in germ line and somatic cells of the antheridia. DNA content increased from 2C up to 128C in shield cells, manubria and capitular cells. However, a progressive decrease in the amount of DNA after any successive endoreplication cycle was apparent in the antheridial non-generative cells suggesting a possible presence of a DNA remodeling mechanism in Chara. The 1C-value found in the cells of the filaments at a mature stage of spermiogenesis has an absolute content of 4.47 pg. The obtained data on DNA amount was combined and analyzed with those available on Chara spp. in the literature. An n = 14 chromosome number was confirmed for this population. Spontaneous anomalies such as laggard chromosomes, formation of micronuclei or amitotic nuclear divisions by gradually pulling apart the nucleus into two parts, were observed in some cells of the antheridial filaments.

Albendazole-induced genotoxicity in the larvae of fall armyworm as a safe environmental tool

Anthelmintic drugs are considered a new alternative strategy to control insect pests. Spodoptera frugiperda, fall armyworm (FAW), is one of the most serious pests of maize and cultivated plants. Albendazole (ABZ) is one of the safest anthelmintic drugs and is used worldwide in human and veterinary medicine. ABZ has not previously been used for controlling FAW, so the present study aimed to investigate the insecticidal and genotoxic effects of ABZ on FAW. ABZ produced a significant effect on the mortality of FAW. Also, drug treatment significantly disrupted the larval, pupal, and adult durations associated with malformations. Because ABZ interferes with microtubule formation, it could induce mortality and affect all physiological processes in FAW. Additionally, it can disrupt the chromosomes' alignment and result in the formation of micronuclei (MN), DNA damage, and cell death, thus causing ABZ-induced genotoxic effects on FAW larval hemocytes. The present study shows that the ABZ drug has a strong insecticidal potency and is a promising environmental safety tool to control the fall armyworm pest.Graphical abstract

Genotoxic Potential, Total Flavonoid and Phenolic Contents of Solanum anomalum Thonn. Ex Schumach Leaf

Solanum anomalum, a medicinal plant, used in ethnomedicine for their antimalarial, antidiabetic, and antiphlogistic activities was investigated for cytotoxic and genotoxic effects on the root meristem cells of Allium cepa. The extract and fractions was also screened for total flavonoid and phenol content using standard methods. Onion bulbs were exposed to 2.5 mg/mL, 5mg/mL, and 10 mg/mL concentrations of the leaf extract for macroscopic and microscopic analysis. Tap water was used as a negative control and Methotrexate (0.1 mg/mL) as a positive control. There was statistically significant (P < 0.05) inhibition of root growth depending on concentration by the extract when compared with the negative control group. All the tested concentrations of the extract were observed to have cytotoxic effects on cell division in A. cepa. The extract- induced chromosomal aberrations and micronuclei (MNC) formations in A. cepa root tip cells were significant (p<0.05) when compared with control group. The extract treatment further induced cell death, ghost cells, cells membrane damage, and binucleated cells. The dichloromethane fraction was found to contain the highest level of total flavonoid and phenol followed by the crude extract. These results suggest that Solanum anomalum leaf extract possess cytotoxic and genotoxic effects on A. cepa which is as a results of its phytochemical constituents.

Evaluation of cyto-genotoxicity biomarkers, changes in histology and antioxidant defense system of Oreochromis niloticus induced by the industrial effluents

Aquatic pollution mainly by industrial effluents has been a major concern since a few decades. The current study evaluated cyto-genotoxicity of industrial effluents on Oreochromis niloticus exposed to sublethal levels by hematotoxicity, blood biochemistry analysis, micronucleus assay, antioxidants and cerebral toxicity. The significant elevation in differential leukocytes of exposed fish was indicative of infections and compromised immune system. The acute and chronic industrial effluent exposure caused significant decline in aspartame transaminase (AST) and alanine transaminase (ALT) and renal function enzymes. Necrosis, hyperplastic growth, hypertrophy and toxicant accumulation exhibited cerebral toxicity potential of industrial toxicants. A significant decrease in antioxidants, GSH, SOD and catalase (0.14, 0.66 and 1549 unit/mg protein) in chronic exposure group in comparison to 0.18, 2.83, 7680 and 6200.8 values of GSH, SOD, GPx and CAT, respectively. Results showed that acute and chronic industrial effluent exposure caused genotoxicity with higher frequencies of formation of micronuclei and cytokaryotic fusion.

REV7 Monomer Is Unable to Participate in Double Strand Break Repair and Translesion Synthesis but Suppresses Mitotic Errors.

Rev7 is a regulatory protein with roles in translesion synthesis (TLS), double strand break (DSB) repair, replication fork protection, and cell cycle regulation. Rev7 forms a homodimer in vitro using its HORMA (Hop, Rev7, Mad2) domain; however, the functional importance of Rev7 dimerization has been incompletely understood. We analyzed the functional properties of cells expressing either wild-type mouse Rev7 or Rev7K44A/R124A/A135D, a mutant that cannot dimerize. The expression of wild-type Rev7, but not the mutant, rescued the sensitivity of Rev7-/- cells to X-rays and several alkylating agents and reversed the olaparib resistance phenotype of Rev7-/- cells. Using a novel fluorescent host-cell reactivation assay, we found that Rev7K44A/R124A/A135D is unable to promote gap-filling TLS opposite an abasic site analog. The Rev7 dimerization interface is also required for shieldin function, as both Rev7-/- cells and Rev7-/- cells expressing Rev7K44A/R124A/A135D exhibit decreased proficiency in rejoining some types of double strand breaks, as well as increased homologous recombination. Interestingly, Rev7K44A/R124A/A135D retains some function in cell cycle regulation, as it maintains an interaction with Ras-related nuclear protein (Ran) and partially rescues the formation of micronuclei. The mutant Rev7 also rescues the G2/M accumulation observed in Rev7-/- cells but does not affect progression through mitosis following nocodazole release. We conclude that while Rev7 dimerization is required for its roles in TLS, DSB repair, and regulation of the anaphase promoting complex, dimerization is at least partially dispensable for promoting mitotic spindle assembly through its interaction with Ran.

Evaluation of Mitigation Role of L-Phenylalanine-Based Low-Molecular-Weight Gelator against Oil Pollution-Induced Nile Tilapia Toxicity.

A lot of oil is leaked into aquatic environments, significantly impacting fish health and, consequently, human populations. This study aimed to introduce an L-phenylalanine-based low-molecular-weight gelator (expressed as Z-Phe-C18) as a smart remediation tool for oil spills. Several groups of Nile tilapia were allocated in aquaria exposed to different doses of crude engine oil with/without the organogelator for 4 weeks. The results revealed a significant increase in biochemical oxygen demand, chemical oxygen demand, electrical conductivity, and total dissolved solids in water samples of fish aquaria exposed to oil pollution. The antioxidant activity levels, micronucleus formation, and expression patterns of stress-related genes were significantly higher in the livers of fish exposed to crude oil than in those of control fish. On the contrary, fish groups exposed to oil pollution and treated with the organogelator indicated that antioxidant enzymes, micronucleus incidence, and gene expression alteration of stress-related genes declined compared with those exposed to oil pollution only. The results suggest that oil pollution can induce oxidative stress via the enhancement of oxygen free radical formation. On the contrary, oil removal by the organogelator decreases oxidative stress and consequently strengthens fish immunity. So, we can conclude that organogelator treatment is promoting oxidative resistance development by increasing the activities of antioxidant enzymes, which are important in protection against oil pollution and preventing peroxidation of fish tissues. Promisingly, the organogelator could be used as a tool for the remediation of oil pollution in aquatic environments.

Effects of haloperidol on peripheral erythrocytes and brain neurotransmitter levels of juvenile African Sharptooth Catfish Clarias gariepinus.

The study investigated the effects of haloperidol on peripheral erythrocytes and brain neurotransmitter levels of juvenile African Sharptooth Catfish Clarias gariepinus. Juveniles were exposed to different concentrations of haloperidol (0.12, 0.24, and 0.48 mg/L) for 15 days and subsequently withdrawn from the drug for 5 days. Blood samples from the fish on days 1, 5, 10, and 15 and after the 5-day withdrawal period were analyzed for mutagenic changes, after which the fish were sacrificed. The brain was sampled for serotonergic and dopaminergic analyses. There was formation of micronuclei in the peripheral fish blood, which increased as the duration and concentrations of the drug increased. The drug significantly reduced the serotonin activity but increased dopamine activity. Some of the studied parameters, however, recovered from the effects of the drug after the 5-day withdrawal period. Haloperidol is toxic to fish, and its use in the environment should be guarded to avoid adverse impacts on nontarget species like fish.

Targeting mitotic regulators in cancer as a strategy to enhance immune recognition

Eukaryotic DNA has evolved to be enclosed within the nucleus to protect the cellular genome from autoinflammatory responses driven by the immunogenic nature of cytoplasmic DNA. Cyclic GMP-AMP Synthase (cGAS) is the cytoplasmic dsDNA sensor, which upon activation of Stimulator of Interferon Genes (STING), mediates production of pro-inflammatory interferons (IFNs) and interferon stimulated genes (ISGs). However, although this pathway is crucial in detection of viral and microbial genetic material, cytoplasmic DNA is not always of foreign origin. It is now recognised that specifically in genomic instability, a hallmark of cancer, extranuclear material in the form of micronuclei (MN) can be generated as a result of unresolved DNA lesions during mitosis.Activation of cGAS-STING in cancer has been shown to regulate numerous tumour-immune interactions such as acquisition of ‘immunologically hot’ phenotype which stimulates immune-mediated elimination of transformed cells. Nonetheless, a significant percentage of poorly prognostic cancers is ‘immunologically cold’. As this state has been linked with low proportion of tumour-infiltrating lymphocytes (TILs), improving immunogenicity of cold tumours could be clinically relevant by exhibiting synergy with immunotherapy. This review aims to present how inhibition of vital mitotic regulators could provoke cGAS-STING response in cancer and improve the efficacy of current immunotherapy regimens.

Plant cytogenetics tests can predict toxic effects on human cells: genotoxic and mutagenic effects of Tityus serrulatus scorpion venom on vegetal and human cells

The effects of Tityus serrulatus venom was accessed on the cell cycle and genetic material of the Lactuca sativa L. and compared with the damages to human leukocytes, in order to evaluate the genotoxic and mutagenic potential of toxins on cell types very different. The occurrence of cell cycle alterations and DNA fragmentation was evaluated in Lactuca sativa. Incubations of venom with human leukocytes were also held with subsequent evaluation of cell proliferation index, micronucleus and fragmented DNA. The T. serrulatus venom showed cytogenotoxic, reducing mitotic index and induced alterations in the cell cycle and micronuclei formation. The occurrence of cell death was evidenced by the detection of condensed nuclei, positive TUNEL signals, and presence of DNA fragmentation on lettuce cells. The scorpion venom induced DNA fragmentation and micronuclei in leukocytes. Further, the role of peptides and proteases from this venom in inducing the observed damage was discussed.

RED RICE BRAN EXTRACT SUPPRESSES COLON CANCER CELLS VIA APOPTOSIS INDUCTION/CELL CYCLE ARREST AND EXERTS ANTIMUTAGENIC ACTIVITY.

Red rice bran extract (RRBE) contains many biologically active substances exerting antioxidant and anti-inflammatory effects. To evaluate the anticancer potential of RRBE in human colon cancer cells and its mutagenic/antimutagenic effects on nonmalignant cells. The cytotoxic effect of RRBE was determined by trypan blue exclusion in HCT116, HT29 cell lines and a non-cancerous HEK293 cell line, and its antiproliferative effect using MTS and colony formation assay. The apoptosis induction was evaluated using ELISA, and the apoptotic rate and cell cycle progression were assessed by flow cytometry. The mutagenic/ antimutagenic potential of RRBE was analyzed by micronucleus assay in the V79 cell line. RRBE caused a dose-dependent reduction of cell viability in colon cancer cells and showed a limited cytotoxicity against HEK293 cells. The treatment with RRBE suppressed proliferation of HCT116 and HT29 cells and induced apoptosis as evidenced by the increased DNA fragmentation and the apoptotic cell counts. Furthermore, RRBE treatment significantly increased the number of cells at the G2/M phase triggering the arrest of the cell cycle in colon cancer cells. Interestingly, RRBE did not increase the micronucleus frequency in V79 cells but reduced the micronucleus formation caused by mitomycin C. RRBE effectively suppressed proliferation, induced apoptosis, and caused a cell cycle arrest in human colon cancer cells while being non-mutagenic and exerting antimutagenic effects in vitro.

The cGAS/STING/IFN-1 Response in Squamous Head and Neck Cancer Cells after Genotoxic Challenges and Abrogation of the ATR-Chk1 and Fanconi Anemia Axis.

Locally advanced head and neck squamous cell carcinomas (HNSCC) are often refractory to platinum-based radiochemotherapy and new immuno-oncological strategies. To stimulate immunogenic antitumor responses in HNSCC patients, we investigated the cGAS/STING/IFN-1 signaling pathway after genotoxic treatments and concomitant abrogation of the DNA damage response (DDR). For this purpose, FaDu and UM-SCC1 cells were exposed to X-rays or cisplatin and treated with an ATR or Chk1 inhibitor, or by Fanconi anemia gene A knockout (FANCA ko). We assessed clonogenic survival, cell cycle regulation, micronuclei, free cytosolic double-stranded DNA, and the protein expression and activity of the cGAS/STING/IFN-1 pathway and related players. Cell survival, regulation of G2/M arrest, and formation of rupture-prone cGAS-positive micronuclei after genotoxic treatments were most affected by ATR inhibition and FANCA ko. In UM-SCC-1 cells only, 8 Gy X-rays promoted IFN-1 expression unaltered by abrogation of the DDR or concomitant increased TREX1 expression. At a higher dose of 20 Gy, this effect was observed only for concurrent Chk1- or ATR-inhibition. FANCA ko or cisplatin treatment was ineffective in this regard. Our observations open new perspectives for the enhancement of cGAS/STING/IFN-1-mediated antitumor immune response in HNSCC by hypofractionated or stereotactic radiotherapy concepts in multimodal settings with immuno-oncological strategies.

Micronuclei in human peripheral blood and bone marrow as genotoxicity markers: A systematic review and meta-analysis.

Can human peripheral blood cells be used as a surrogate for bone marrow cells, in evaluating the genotoxic effects of stressors? We searched the Pubmed/Medline and PubChem databases to identify publications relevant to this question. Micronucleus formation was the genotoxicity endpoint. Three publications comparing exposed vs. non-exposed individuals are included in this analysis; the exposures were to ethylene oxide or ionising radiation (atomic bomb, thorotrast, or radioiodine therapy). Information was extracted on the types of exposure, the numbers of participants, and the micronucleus frequencies. Relative differences (odds ratios) and absolute differences (risk differences) in the numbers of micronuclei between exposed and non-exposed persons were calculated separately for individual cell types (peripheral blood and bone marrow). Random effects meta-analyses for the relative differences in cell abnormalities were performed. The results showed very small differences in the frequencies of micronuclei between exposed and non-exposed individuals, as measured in either peripheral blood or bone marrow cell populations, on both absolute and relative scales. No definite conclusion concerning the relative sensitivities of bone marrow and peripheral blood cells can be made, based on these publications.

POT1 involved in telomeric DNA damage repair and genomic stability of cervical cancer cells in response to radiation.

Though telomeres play a crucial role in maintaining genomic stability in cancer cells and have emerged as attractive therapeutic targets in anticancer therapy, the relationship between telomere dysfunction and genomic instability induced by irradiation is still unclear. In this study, we identified that protection of telomeres 1 (POT1), a single-stranded DNA (ssDNA)-binding protein, was upregulated in γ-irradiated HeLa cells and in cancer patients who exhibit radiation tolerance. Knockdown of POT1 delayed the repair of radiation-induced telomeric DNA damage which was associated with enhanced H3K9 trimethylation and enhanced the radiosensitivity of HeLa cells. The depletion of POT1 also resulted in significant genomic instability, by showing a significant increase in end-to-end chromosomal fusions, and the formation of anaphase bridges and micronuclei. Furthermore, knockdown of POT1 disturbed telomerase recruitment to telomere, and POT1 could interact with phosphorylated ATM (p-ATM) and POT1 depletion decreased the levels of p-ATM induced by irradiation, suggesting that POT1 could regulate the telomerase recruitment to telomeres to repair irradiation-induced telomeric DNA damage of HeLa cells through interactions with p-ATM. The enhancement of radiosensitivity in cancer cells can be achieved through the combination of POT1 and telomerase inhibitors, presenting a potential approach for radiotherapy in cancer treatment.

Formalin Induced Micronucleus Formation in the Buccal Mucosa of Pathology Laboratory Workers.

Formaldehyde is an irritating substance that is categorized as a definite carcinogen (Group A1), according to the International Agency for Research on Cancer (IARC). This study was conducted to determine the role of this substance in the frequency of micronuclei (MN) in the buccal mucosal cells due to long-term exposure of the pathology staff to formaldehyde. In this case-control study, 32 pathology laboratory staff members were assigned to the case group, and 32 staff members who were not exposed to formaldehyde were assigned to the control group. Buccal mucosa cells were collected with a wet spatula and stained with Papanicolaou stain. In each sample, 500 cells were counted; then, the frequency of MN and the average number of MN in the micronucleated cells were assessed and compared between the 2 groups using the independent t test. Furthermore, the relationship between gender and MN was evaluated using the independent t test. The relationship between years of exposure and time of exposure during the day (in hours) for the case group, as well as the relationship between age and frequency of MN was analyzed using the Pearson correlation coefficient. The mean frequency of MN in exfoliated buccal cells was 18.33±12.36 in the case group, which was significantly higher than the control group (10.55±6.22; P=0.003). The difference in the mean number of total MN in the micronucleated cells was not significant between the case and control groups (P=0.11). The relationship between sex, age, and years of exposure with the mean frequency of MN and the total number of MN in the micronucleated cells was not significant. The relationship between exposure time during the day and both the mean frequency of MN and the total number of MN in the micronucleated cells was significant (P=0.03). Formaldehyde exposure and extended time of exposure during the day can increase the frequency of MN, which can prognosticate the incidence of precancerous and cancerous lesions. Therefore, continuous exposure to formaldehyde can be considered an occupational health hazard, though further studies are needed to confirm this result.

Assessment of the in vivo genotoxic potential of three smoke flavoring primary product mixtures.

Smoke flavorings are mixtures generated from wood pyrolysis that are filtered to remove tar and are often considered healthier alternatives to conventional smoking processes. While the latter is mostly unregulated, smoke-flavoring primary products (SFPPs) are undergoing the 10-year required re-evaluation in the European Union (EU). To comply with recent smoke flavor guidance, in vivo micronucleus studies in rats and transgenic rodent (TGR) mutation assays in Muta™Mice were conducted on three SFPPs. For most studies, typical limit doses were exceeded to comply with regulatory requests. Exposure to SFPPs by oral gavage did not result in significant increases in bone marrow micronucleus formation. Except for one group, exposure to SFPPs via feed for 28 days did not result in significant increases in mutant frequency (MF) in the glandular stomach or liver. One group exposed to a maximal feasible dietary dose of 50,000 ppm (>10,000 mg/kg bodyweight per day) exhibited a statistically significant increase in liver MF; however, the MF in all mice in this group were within the historical vehicle control 95% quantile confidence intervals and therefore not considered biologically relevant. Based on estimates of human dietary exposure to each SFPP, the margin of exposure (MOE) values in the TGR assays exceed 10,000. The MOE for one unintentionally present constituent, 2,5(H)-furanone, also exceeds 10,000. Collectively, these data indicate that these SFPPs pose no genotoxic risk and are safe alternatives to conventional smoking.

Degenerative Changes of Buccal Cells After One Cycle of Chemotherapy on Male Breast Cancer Patients

Introduction: Micronucleus test (MN) in buccal cells of the mouth presents a new road on the way of studying the degenerative changes directly in the targeted organs which were impacted by the tumoral diseases. Aim of the study: This paper aims to analyze the incidence of the test micronucleus in the epithelial cells of the buccal mucosa of the oral cavity in male patients with breast carcinoma after a cycle of chemotherapy. Material and Methods: In the study, 40 male patients with breast cancer with an average age of 45.8±15.5 years were taken for analysis. From the measured parameters, we analyzed the incidence of degenerative changes and the effect of chemotherapy, after one cycle of chemotherapy. Results: The average number of deteriorative modifications in the exfoliative cells deriving from the buccal mucosa of breast cancer patients, increased significantly after a single cycle of chemotherapy with 15.5±22.4 being the number of degenerated cells before treatments and 27.5±30.1 after the first cycle of chemotherapy, p<0.0002. A significant increase was noticed in all types of nuclear degenerations. The incidence of acute nuclear changes as well as the total number of these modifications was high in males diagnosed with breast carcinoma Conclusion: The results show that cytostatic drugs induced cellular cytotoxicity. However, it did not significantly change chromosomal changes or the micronuclei formation.