Mutagenicity and safety evaluation of Ashwagandha (Withania somnifera) root aqueous extract in different models

Withania somnifera (Ashwagandha) also called as Indian ginseng, a revered herb from Indian traditional system of medicine is a rejuvenator and tonic (Rasayana) used for its varied benefits. The roots of ashwagandha exhibit properties like anti-inflammatory, aphrodisiac, anthelmintic, astringent, diuretic, stimulant and thermogenic. However, data of ashwagandha on its mutagenic effects are lacking. In the present study, in-vitro genotoxicity tests were used to evaluate the mutagenic potential of Ashwagandha Root Extract (ARE). Concentrations of 0.156 to 5.00 mg/plate ARE were used for conducting Bacterial reverse mutation test (BRMT). For chromosome aberration (CA) test ARE was used in concentrations of 0.25 to 2.00 mg/ml, and for micronucleus (MN) tests ARE concentrations of 500/1000/2000 mg/kg were used. Acute oral toxicity was conducted in Wistar rats (n = 25) as per the OECD guideline (#423) with doses of 500/1000/2000 mg/kg body weight in male Swiss albino mice for morbidity and mortality for 3 days. The BRMT and CA tests were conducted with and without metabolic activation (S9). The study was approved by the institutional ethics committee (IEC) and institutional animal ethics committee (IAEC). ARE failed to show any mutagenic effects up to a dose of 5 mg/plate in BRMT. Also, ARE did not show any clastogenic activity in doses up to 2 mg/ml in CA test and in micronucleus test up to 2000 mg/kg body weight. These results were observed with and without metabolic activation (S9) under the stated experimental conditions. No mortality, morbidity, or any clinical signs were observed up to 3 days following ARE administration. Ashwagandha root extract failed to show any mortality in doses up to 2000 mg/kg oral dosage and did not show any mutagenic (genotoxic) effects in high concentrations.

The toxic mechanism of tetracycline on root tips in hulless barley (Hordeum vulgare L. var. nudum)

Tetracycline (TC) is a commonly used antibiotic that affects various physiological processes in plants. However, its negative effects on plants remain poorly understood at the molecular level. To ascertain the TC toxicity in the roots, transcriptomic, cytological, and physiological analyses were performed to explore the molecular mechanisms of TC influencing the growth of hulless barley root. At a low concentration (1 mg/L), TC promoted root growth by upregulating the genes related to the flavonoid pathway. At high concentrations (10, 100, and 200 mg/L), TC downregulated genes related to homologous recombination in the root meristem zone and inhibited the mitosis index by 16.4%. Disruption of the DNA repair process can lead to chromosomal aberrations, resulting in a 6.8% C-mitosis rate in the most severe cases. Finally, root growth was inhibited by TC, as evidenced by a reduction in root viability, an increase in reactive oxygen species content, and an inhibition of root length. Cross-comparison of physiological and cytological characterizations and transcriptomic information revealed changes in genetic processes under TC stress. Overall, we present an early genetic strategy to study the significant influence of TC stress on roots.

Risk factor analysis for adverse prognosis of the fetal ventricular septal defect (VSD)

BACKGROUND

Ventricular septal defect (VSD) is the most common subtype of congenital heart disease. In the present study, we aimed to determine whether chromosome aberration was associated with the occurrence of VSD and evaluate the association of VSD size, location and chromosome aberration with adverse outcomes in the Chinese fetuses.

METHODS

Fetuses with VSD and comprehensive follow-up data were included and evaluated retrospectively. Medical records were used to collect epidemiological data and foetal outcomes. For VSD fetuses, conventional karyotype and microarray analysis were conducted. After adjusting confounding factors by using multivariable logistic regression analyses, the association between chromosome variations and VSD occurrence was explored. The association between defect size, location and chromosome aberrations and adverse foetal outcomes was also investigated.

RESULTS

Chromosome aberration was the risk factor for VSD occurrence, raising 6.5-fold chance of developing VSD. Chromosome aberration, peri-membranous site and large defect size of VSD were significant risk factors of adverse fetal outcome. Chromosome aberrations, including pathogenic copy number variations (CNVs) and variations of uncertain significance (VUS), were both risk factors, increasing the risk of the adverse fetal outcome by 55.9 times and 6.7 times, respectively. The peri-membranous site would increase 5.3-fold risk and defects larger than 5 mm would increase the 7.1-fold risk for poor fetal outcome.

CONCLUSIONS

The current investigation revealed that chromosomal abnormalities, large defects, and the peri-membranous site were all risk factors for poor fetal outcomes. Our study also indicated that chromosome aberration was one of risk factors for the VSD occurrence.

[Analysis of chromosome aberrations in peripheral blood lymphocyte of medical radiation workers in a tertiary hospital]

Objective: To analyze the level of chromosome aberration in lymphocytes of medical radiation workers and its influencing factors. Methods: From July to September 2020, 252 medical workers in a tertiary hospital were selected as the study subjects and 107 preserviceworkers were selected as the control group. The Chromosomal aberrations of peripheral blood lymphocytes were measured using conventional cytogenetic analysis method, and the differences were analyzed. Results: The frequencies of dicentric puls centric ring, total chromosome-type aberrations, and abnormal detection rate in the radiation group were significantly higher than those in the control group (Z=2.59, 3.74, 9.99, P<0.05). There was significant difference in the frequencies of dicentric plus centric ring and total chromosome-type aberrations among different types of work (χ(2)=8.59, 8.17, 11.39, P<0.05), and the frequencies of dicentric plus centric ring were significantly higher in the interventional radiology group than those in diagnostic radiology (χ(2)=2.90, P<0.05), While the rates of acentric fragment and total chromosome-type aberrations were significantly higher in the nuclear medicine group than those in diagnostic radiology (χ(2)=2.81, 3.19, P<0.05). The difference in the abnormal detection rate of chromosome aberrations between different types of work was statistically significant (P<0.05), and the rate in the interventional radiology group was significantly higher than that in the diagnostic radiology group (χ(2)=7.66, P<0.05). There was no significant difference in chromosome aberration level and abnormal detection rate among different working ages (P>0.05). Poisson regression analysis indicated that the type of work is a risk factor for chromosomal aberration [IRR=2.31 (nuclear medicine group), 1.66 (Radiation therapy), and 1.78 (interventional group) ; P<0.05]. Conclusion: Ionizing radiation causes certain radiation damage to medical radiology workers, and the frequencies of chromosome aberration in the radiation workers of nuclear medicine and interventional radiology groups are relatively high, so radiation protection should be strengthened to ensure the health of relevant workers.

Modeling of ionizing radiation-induced chromosome aberration and tumor prevalence based on two classes of DNA double-strand breaks clustering in chromatin domains

There has been some controversy over the use of radiobiological models when modeling the dose-response curves of ionizing radiation (IR)-induced chromosome aberration and tumor prevalence, as those curves usually show obvious non-targeted effects (NTEs) at low doses of high linear energy transfer (LET) radiation. The lack of understanding the contribution of NTEs to IR-induced carcinogenesis can lead to distinct deviations of relative biological effectiveness (RBE) estimations of carcinogenic potential, which are widely used in radiation risk assessment and radiation protection. In this work, based on the initial pattern of two classes of IR-induced DNA double-strand breaks (DSBs) clustering in chromatin domains and the subsequent incorrect repair processes, we proposed a novel radiobiological model to describe the dose-response curves of two carcinogenic-related endpoints within the same theoretical framework. The representative experimental data was used to verify the consistency and validity of the present model. The fitting results indicated that, compared with targeted effect (TE) and NTE models, the current model has better fitting ability when dealing with the experimental data of chromosome aberration and tumor prevalence induced by multiple types of IR with different LETs. Notably, the present model without introducing an NTE term was adequate to describe the dose-response curves of IR-induced chromosome aberration and tumor prevalence with NTEs in low-dose regions. Based on the fitting parameters, the LET-dependent RBE values were calculated for three given low doses. Our results showed that the RBE values predicted by the current model gradually decrease with the increase of doses for the endpoints of chromosome aberration and tumor prevalence. In addition, the calculated RBE was also compared with those evaluated from other models. These analyses show that the proposed model can be used as an alternative tool to well describe dose-response curves of multiple carcinogenic-related endpoints and effectively estimate RBE in low-dose regions.

FISH with Whole Chromosome Painting Probes

Some types of chromosome aberrations are not easily identified by the traditional Giemsa staining. It usually needs some banding technique and skilled person's eye. Whole chromosome painting FISH probe can stain designated entire chromosomes or domains in metaphase chromosomes or interphase nuclei, respectively. It allows to visually identify translocations, deletions, or amplifications of specific chromosomes. Once chromosomes are stained, even non-skilled researchers can easily identify those chromosome aberrations. Whole chromosome painting FISH has higher sensitivity to detect chromosome aberrations. This chapter introduces the method for whole chromosome painting FISH staining.

Neoplasia-associated Chromosome Translocations Resulting in Gene Truncation

Chromosomal translocations in cancer as well as benign neoplasias typically lead to the formation of fusion genes. Such genes may encode chimeric proteins when two protein-coding regions fuse in-frame, or they may result in deregulation of genes via promoter swapping or translocation of the gene into the vicinity of a highly active regulatory element. A less studied consequence of chromosomal translocations is the fusion of two breakpoint genes resulting in an out-of-frame chimera. The breaks then occur in one or both protein-coding regions forming a stop codon in the chimeric transcript shortly after the fusion point. Though the latter genetic events and mechanisms at first awoke little research interest, careful investigations have established them as neither rare nor inconsequential. In the present work, we review and discuss the truncation of genes in neoplastic cells resulting from chromosomal rearrangements, especially from seemingly balanced translocations.

New cytogenetic data on Caryophyllaeus laticeps and Paracaryophyllaeus gotoi, parasites of evolutionary interest

Caryophyllideans are intestinal parasites of freshwater fishes, occupying a basal position among the ‘true’ tapeworms. We performed detailed cytogenetic analyses of the well-known caryophyllidean species Caryophyllaeus laticeps. For comparison, we also examined for the first time the chromosomes of Paracaryophyllaeus gotoi, a specific parasite of loaches in China. Both species showed a diploid chromosome number of 2n = 20, n = 10m. Chromomycin A3 (CMA3)/diamidino-2-phenylindole (DAPI) staining performed for the first time in the class Cestoda revealed CMA3+/DAPI− bands in the pericentromeric regions of the short arms of chromosome pair no. 7 in the karyotype of C. laticeps. Fluorescence in situ hybridization with the 18S rDNA probe confirmed the presence of a single cluster of major rDNA near the centromere on a pair of small chromosomes in both species. These findings support the hypothesis that the ancestral state in the family Caryophyllaeidae is a single interstitial cluster of major rDNA genes and thus one nucleolar organizer region per haploid genome. Our results, which we presented together with literature data plotted on a phylogenetic tree, show stability of caryophyllidean karyotypes at the genus level, but showed differences between genera without a clear phylogenetic signal. The data allowed us to at least formulate a hypothesis about the ancestral haploid chromosome number of n = 10 for the family Caryophyllaeidae and possibly for the sister family Capingentidae. In addition, we compared two populations of C. laticeps from water bodies with different levels of polychlorinated biphenyl contamination, showing a slightly increased incidence of chromosomal abnormalities at the contaminated site.

Placing women in Cytogenetics: Lore Zech and the chromosome banding technique

BACKGROUND

Scholars agree that Torbjörn Caspersson's lab at the Institute of Medical Cell Research and Genetics at the Karolinska Institute, Sweden, played a key role in the first description of the so-called Q-banding technique. It laid the foundation for a new era of cytogenetic diagnostics and had a lasting impact in several areas of biology and medicine.

METHODS

Based on a mixed-method approach, essential aspects of the history of human cytogenetics are considered via primary and secondary analysis of biographical interviews as well as the qualitative evaluation of bibliometrics. Drawing on interviews with colleagues of lab member Lore Zech (1923-2013) and contemporary publications, this paper illuminates the role of and contribution by Zech: To what extent is the discovery attached to her and what does her legacy look like today?

RESULTS

The analysis of the contemporary witness interviews with colleagues, students and junior researchers shows that Lore Zech was a committed member of Caspersson's research group. In addition, memoirs by contemporary colleagues describe her outstanding skills in microscopy. The different sources paint a multifaceted picture. In addition to the historians' patterns of interpretation, different legacies can also be found within the peer group.

CONCLUSIONS

We argue that Zech represent the type of scientist who, although her research was acknowledged with several prizes, so far has not been part of the canon of pioneers of international cytogenetics.

The genotoxic effects of perchloroethylene in human peripheral blood lymphocytes and the possible ameliorative role of α-tocopherol

Perchloroethylene (PCE), also known as tetrachloroethylene, is a commercially important chlorinated solvent commonly used in dry cleaning, textile processing, and metal degreasing industries. According to the available studies, the potential genotoxic impacts of this chlorinated solvent on human beings are still controversial. The present work was carried out to determine the genotoxic effects of PCE on human peripheral blood lymphocytes (PBLs) using chromosome aberrations (CAs) and cytokinesis-block micronucleus (CBMN) tests. Additionally, the antigenotoxic potential of α-tocopherol (α-Toc), a well-known antioxidant agent, on human lymphocytes treated with PCE in vitro was assessed. The cells were exposed for 48 h to PCE (25, 50, 100, and 150 μg/mL) alone as well as in combination with α-Toc (100 μg/mL). The findings of the study suggested that, relative to solvent control, PCE significantly increased the structural CA and MN formation for all concentrations. However, simultaneous treatment of PCE and α-Toc caused a significant reduction of CAs and MNi as compared to cultures treated with PCE alone. Besides, the results showed that PCE has cytotoxic effects on human PBLs as indicated by the significant decrease in mitotic index (MI) and nuclear division index (NDI). Nevertheless, the co-treatment of α-Toc with PCE did not reduce the cytotoxicity of PCE at a significant level. In conclusion, it can be suggested that PCE is genotoxic and cytotoxic in human PBLs, and α-Toc has an antigenotoxic effect on PCE-induced genotoxicity but has no significant effect on the cytotoxicity triggered by PCE.

The association of three DNA repair genes polymorphisms on the frequency of chromosomal alterations detected by fluorescence in situ hybridization

PURPOSE

Gas station workers (GSWs) are exposed to carcinogenic agents. The aim was to study the association of high somatic chromosome alterations (CAs) rates in the blood of GSWs and the polymorphisms of three genes playing a role in DNA double-strand break repair.

METHODS

This is a cross-sectional study with 114 GSWs and 115 age-matched controls. Cytogenetic analyses, blood exams, medical interviews and genotypes for RAD51/G135C (rs1801320), ATM/P1054R (rs1800057) and CHEK2/T470C (rs17879961) genes were performed.

RESULTS

The CA rate in GSWs was 9.8 CAs/1000 metaphases, and 19.1% of the workers had > 10 CAs per 1000 metaphases (group two). GSWs had decreased levels of monocytes (P = 0.024) in their blood exams. The number of variant alleles of the RAD51/G135C polymorphism was higher in GSWs (P = 0.011) compared to the controls, and were associated with enhanced number of CAs per worker (P = 0.008). No allele variant was found for CHEK2/T470C in this study.

CONCLUSION

The RAD51/G135C polymorphism appears to be related to genome instability in gas station workers. Increasing the knowledge of DNA repair gene variations involved in maintaining genomic stability in GSWs may be crucial for future cancer prevention.

Effect of the duration of use of aluminum cookware on its metal leachability and cytogenotoxicity in Allium cepa assay

Aluminum cookware are widely used in many parts of the world. Data is increasing on the leaching of toxic metals from aluminum cookware into food and drink. In the present study, cytogenotoxicity of water boiled in three different aluminum pots (new, 3-year-old, and 6-year-old) in onion root tip's dividing cells was evaluated using the Allium cepa assay. The concentrations of Pb, As, Cd, Cu, Ni, and Al in the samples were also analyzed. Onion bulbs were grown in the boiled water samples, while tap water served as the control. Cytological and genetic analyses were carried out after 48 h, while analysis of inhibition of root length was carried out after 72 h. The results showed a significant (p < 0.05) cell proliferation and root growth inhibition compared with the control, which is dependent on the duration of use of the aluminum pots. The boiled water samples also caused modification of the root morphology as well as chromosomal aberrations which include sticky chromosomes, anaphase bridge, and disturbed spindle. The highest cytogenotoxicity was observed in the 6-year-old aluminum pot and the least in the new aluminum pot. Pb, As, Cd, Cu, Ni, and Al analyzed in the samples, with the highest concentrations in the 6-year-old aluminum pot, were believed to be responsible for the cytogenotoxicity observed in the A. cepa assay. The data of this study are indications that the aluminum pot-boiled water contains substances with the potential to be cytotoxic and cause mutations in somatic cells of A. cepa.

The absence of genotoxicity of a novel fatty acid amide hydrolase inhibitor, BIA 10-2474

In 2016 one person died and others had neurological sequelae during a clinical trial with BIA 10-2474 (3-(1-(cyclohexyl(methyl)carbamoyl)-lH-imidazol-4-yl)pyridine 1-oxide), a novel fatty acid amide hydrolase (FAAH) inhibitor being developed for the treatment of medical conditions such as pain. Prior to the clinical trial a full battery of regulatory toxicology tests were carried out and this paper describes the genotoxicity/mutagenicity tests undertaken with BIA 10-2474 using the Ames (Salmonella typhimurium) reverse mutation test, the Escherichia coli WP2uvrA forward mutation test, an in vitro chromosome damage assay in human lymphocytes, and an in vivo micronucleus test in mice. All tests were conducted with and without a rat liver S9 metabolic activation system. None of the test results were judged to be positive with regards to the mutagenicity/genotoxicity of BIA 10-2474 making it unlikely that any such effect was involved in the toxicity observed in the clinic.

Genotoxicity of water samples from an area of the Pampean region (Argentina) impacted by agricultural and livestock activities

The aim of this study was to assess the genotoxic potential of surface waters located in a rural area in the north east of Buenos Aires province (Argentina) using the Allium cepa test. Water samples were collected at four sites located in a drainage channel and two sites on the Burgos stream that receives water from the channel, taking into account the sowing and harvesting months and rainfall periods. Analytical determinations revealed high total concentrations of Cd, Cu, Pb, and Zn (maximum values: 0.030, 0.252, 0.176, and 0.960 mg L-1, respectively), and concentrations of glyphosate and its metabolite aminomethylphosphonic acid (AMPA), with maximum values of 13.6 and 9.75 μg L-1, respectively. Statistically positive correlations were observed between the total metal concentrations and precipitation. No cytotoxicity (mitotic index MI) was observed in A. cepa. However, several water samples showed significant increases in micronucleus (MN) frequencies with respect to the controls. No correlations were observed between MN and the abiotic variables or precipitation. These results showed a state of deterioration in the water quality at the rural area studied in Buenos Aires province, and heavy metal contamination may contribute to the genotoxic activity. A. cepa was shown to be a useful tool for the detection of genotoxicity in water samples from areas with agricultural and livestock activities.

Acute toxicity and genotoxicity evaluations of Nattokinase, a promising agent for cardiovascular diseases prevention

Cardiovascular diseases (CVDs) are the leading cause of death in the world; however, current agents for CVDs prevention are still limited. Owing to the serious bleeding risk of Aspirin, FDA recently recommended against it from preventing first heart attacks. Nattokinase (NK), a serine protease possessing many key beneficial effects on cardiovascular system, is being pursued as a promising alternative agent. In light of this, the safety profile of NK, in particular its potential genotoxicity, need to be characterized. The present study is therefore aimed to evaluate the toxicological profile of NK. To assess acute safety, mice were orally administrated with NK at its maximum concentration and the maximum feeding volume twice in a single day, no mortality or toxicological signs were observed. Hence, the maximum daily tolerant dose of NK in mice is up to 480000 FU/kg, which is 1000 times more compared to the recommended daily dose for human. In the genotoxicity studies, NK showed no mutagenic activity as tested by both Ames test and in vivo micronucleus assay. Moreover, NK demonstrated no evidence of potential to induce chromosome aberrations in CHL cells. These results indicate that there is no safety concern for NK in the present preclinical safety studies, supporting the safety of NK as an agent for CVDs prevention.

Cytogenetic and genotoxic effects of 2-chlorophenol on Allium cepa L. root meristem cells

2-Chlorophenol (2-CP), a class of chlorinated organic pollutants like other chlorophenols, is used as intermediate in the synthesis of the higher chlorinated congeners, certain dyes, preservatives, herbicides, fungicides, and plastics. In this study, cytotoxic and genotoxic effects of 2-CP were investigated on the root meristem cells of Allium cepa for its effects on root growth, mitotic index (MI), mitotic phases, chromosomal abnormalities (CAs), and DNA damage by using Allium anaphase-telophase and Comet assays. EC₅₀ of 2-CP value was determined as approximately 25 mg/L by Allium root growth inhibition test. Three concentrations of 2-CP (12.5, 25, and 50 mg/L), distilled water (negative control), and methyl methane sulfonate (MMS, 10 mg/L, positive control) were applied to onion stem cells under different exposure periods (24, 48, 72, and 96 h). All the applied doses of 2-CP slightly decreased MIs. 2-CP induced total CAs such as disturbed anaphase-telophase, chromosome laggards, stickiness, and bridges and also DNA damage at significant levels. These results demonstrate that 2-CP has genotoxic effects in A. cepa root meristematic cells.

Cytotoxicity and genotoxicity effects of water boiled in aluminum vessels on Allium cepa root tip cells

Cookwares made from aluminum (Al) are supposed to be a potential source of Al contamination of food. In this study, the cytotoxicity and genotoxicity effects of water boiled in aluminum cookwares on the dividing cells of onion root tip were examined using Allium cepa assay. Three used aluminum cookwares from different sources were selected. Distilled water was gently boiled in each pot and then used for growing onions. The cells of root tip were analyzed for mitotic and phase indexes as well as aberrations appeared in the interphase and mitotic phase. One way analysis of variance and post-hoc Tukey HSD test were applied for comparison between experimental groups. The results showed that the mitotic index in one of the treated groups increased significantly compared to the control. Also the frequency of prophase in two of treated groups increased significantly compared to that of the control. There was a borderline significant increase in the frequency average of total aberrations from three treated groups compared to that of the control (p value = 0.063). Also, a significant increase was observed in the frequency average of disturbed mitosis from three treated groups compared to that of the control (p value = 0.04). The findings of this preliminary study supported a possible health hazard of aluminum cookwares. Further investigation with larger sample and food with various compositions is needed to reach a full conclusion about the health effect of aluminum cookwares.

Cytogenetic and genotoxic effects of Rosmaniric Acid on Allium cepa L. root meristem cells

Rosmarinic acid (RA) is a natural polyphenol carboxylic acid, an ester of caffeic acid with 3,4-dihydroxyphenyllactic acid, found in many species. Current study was aimed to investigate the mitotic division, chromosomal and genotoxic effects of RA on Allium cepa root meristematic cells. In Allium root growth inhibition test, EC50 value was found as 100 ppm. Three concentrations (50, 100, and 200 ppm) of RA under different exposure periods (24, 48, 72 and 96 h) were employed to onion tuber roots. Distilled water and methyl methane sulfonate (MMS, 10 ppm) were used as a negative and positive control, respectively. 100 (except 24 h) and 200 ppm of RA significantly decreased mitotic index (MI). There was an increase of total chromosomal aberrations (CAs) at 50 ppm and simultaneous decrease of CAs at 200 ppm concentrations (p < 0.05). A significant increase in DNA damage was also observed at 200 ppm by Comet assay. Quantitative analysis of RA in A. cepa root meristem cells was also done by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Further investigations are required to explore the molecular mechanism involved in the cytotoxicity and genotoxicity of RA on plants.

Construction and application of (Q)SAR models to predict chemical-induced in vitro chromosome aberrations

In drug development, genetic toxicology studies are conducted using in vitro and in vivo assays to identify potential mutagenic and clastogenic effects, as outlined in the International Council for Harmonisation (ICH) S2 regulatory guideline. (Quantitative) structure-activity relationship ((Q)SAR) models that predict assay outcomes can be used as an early screen to prioritize pharmaceutical candidates, or later during product development to evaluate safety when experimental data are unavailable or inconclusive. In the current study, two commercial QSAR platforms were used to build models for in vitro chromosomal aberrations in Chinese hamster lung (CHL) and Chinese hamster ovary (CHO) cells. Cross-validated CHL model predictive performance showed sensitivity of 80 and 82%, and negative predictivity of 75 and 76% based on 875 training set compounds. For CHO, sensitivity of 61 and 67% and negative predictivity of 68 and 74% was achieved based on 817 training set compounds. The predictive performance of structural alerts in a commercial expert rule-based SAR software was also investigated and showed positive predictivity of 48-100% for selected alerts. Case studies examining incorrectly-predicted compounds, non-DNA-reactive clastogens, and recently-approved pharmaceuticals are presented, exploring how an investigational approach using similarity searching and expert knowledge can improve upon individual (Q)SAR predictions of the clastogenicity of drugs.

Dose Estimation Curves Following In Vitro X-ray Irradiation Using Blood From Four Healthy Korean Individuals

Cytogenetic dosimetry is useful for evaluating the absorbed dose of ionizing radiation based on analysis of radiation-induced chromosomal aberrations. We created two types of in vitro dose-response calibration curves for dicentric chromosomes (DC) and translocations (TR) induced by X-ray irradiation, using an electron linear accelerator, which is the most frequently used medical device in radiotherapy. We irradiated samples from four healthy Korean individuals and compared the resultant curves between individuals. Aberration yields were studied in a total of 31,800 and 31,725 metaphases for DC and TR, respectively, obtained from 11 X-ray irradiation dose-points (0, 0.05, 0.1, 0.25, 0.5, 0.75, 1, 2, 3, 4, and 5 Gy). The dose-response relationship followed a linear-quadratic equation, Y=C+αD+βD², with the coefficients C=0.0011 for DC and 0.0015 for TR, α=0.0119 for DC and 0.0048 for TR, and β=0.0617 for DC and 0.0237 for TR. Correlation coefficients between irradiation doses and chromosomal aberrations were 0.971 for DC and 0.6 for TR, indicating a very strong and a moderate correlation, respectively. This is the first study implementing cytogenetic dosimetry following exposure to ionizing X-radiation.

CORAL: Building up QSAR models for the chromosome aberration test

A high level of chromosomal aberrations in peripheral blood lymphocytes may be an early marker of cancer risk, but data on risk of specific cancers and types of chromosomal aberrations are limited. Consequently, the development of predictive models for chromosomal aberrations test is important task. Majority of models for chromosomal aberrations test are so-called knowledge-based rules system. The CORAL software (http://www.insilico.eu/coral, abbreviation of “CORrelation And Logic”) is an alternative for knowledge-based rules system. In contrast to knowledge-based rules system, the CORAL software gives possibility to estimate the influence upon the predictive potential of a model of different molecular alerts as well as different splits into the training set and validation set. This possibility is not available for the approaches based on the knowledge-based rules system. Quantitative Structure–Activity Relationships (QSAR) for chromosome aberration test are established for five random splits into the training, calibration, and validation sets. The QSAR approach is based on representation of the molecular structure by simplified molecular input-line entry system (SMILES) without data on physicochemical and/or biochemical parameters. In spite of this limitation, the statistical quality of these models is quite good.

Investigation of genotoxic effects of doripenem using cytogenetic and molecular methods

The main aim of this study was to investigate the genotoxic effects of doripenem (DRP) using both cytogenetic and molecular test systems. Although there have been some studies reporting the effects of DRP, none of them has shown the genotoxic effects of DRP. In order to achieve the main aim of the study, the human peripheral lymphocytes were treated with 100 μg/ml, 200 μg/ml, and 400 μg/ml concentrations of DRP for 24 and 48 hours, and the chromosome aberration (CA) and micronucleus (MN) methods were used as the cytogenetic tests and RAPD-PCR method was used as the molecular test to determine the genotoxic effects of DRP. DRP did not induce the chromosome aberrations and micronucleus frequencies at all concentrations and at all treatment periods. So, it was concluded that DRP did not show any cytotoxic effect. However, DRP increased the number of polymorphic bands and decreased the ratio of genomic template stability, especially at the 48-hour treatment period. In this study, according to the obtained results, it was determined that DRP failed to show any genotoxic risk at the therapeutic doses. This result also indicates that DRP could be a reliable antibiotics according to its rapid metabolism.

Mutagenic and genotoxic effects of Anilofos with micronucleus, chromosome aberrations, sister chromatid exchanges and Ames test

We aimed to evaluate the mutagenic effect of Anilofos, organophosphate pesticide, by using Ames/Salmonella/microsome test. Its cytotoxic and genotoxic effects were also determined by chromosome aberration (CA), sister chromatid exchange (SCE) and micronucleus (MN) test in human peripheral blood lymphocytes. In the Ames test, five different concentrations of Anilofos were examined on TA97, TA98, TA100 and TA102 strains in the absence and presence of S9 fraction. According to the results all concentrations of this pesticide have not shown any mutagenic activity on TA97, TA100 and TA102 strains in the absence and presence of S9 fraction. But, 10, 100 and 1000 µg/plate concentrations of Anilofos were determined to be mutagenic on TA98 strain without S9 fraction. Lymphocytes were treated with various concentrations (25, 50, 100 and 200 µg/ml) of Anilofos for 24 and 48 h. The results of the assays showed that Anilofos did not induce SCE frequency, replication index and MN formation at all concentrations for both treatment periods. Anilofos significantly increased CA frequency at 100 and 200 µg/ml concentrations at 24 h treatment periods and at 50, 100 and 200 µg/ml concentrations in 48 h treatment periods. Additionally, it was determined that this pesticide decreased mitotic index and nuclear division index significantly. It was concluded that Anilofos has genotoxic and cytotoxic effects in human peripheral lymphocytes.

Genotoxicity and growth inhibition effects of aniline on wheat

Aniline is a synthetic compound widely used in industrial and pesticide production, which can lead to environmental pollution. Its high concentration in rivers and lakes is hazardous to aquatic species. Although the mechanism of aniline toxicity has been studied extensively in animals and algae, little is known about its genotoxicity in plants. In this study, we investigated the genotoxicity effects of aniline on wheat root tip cells. The mitotic index of wheat root tip cells decreased when the aniline test concentration was higher than 10 mg L^-1. The frequency of micronucleus and chromosomal aberrations increased at aniline concentrations ranging between 5 and 100 mg L^-1, and reached 23.3‰ ± 0.3‰ and 8.9‰ ± 0.68‰, respectively, at an aniline concentration of 100 mg L^-1. These values were sevenfold higher than those in the control group. The wheat seedlings showed various growth toxicity effects under different concentrations of aniline. The shoot height, root length, fresh weight, and dry weight of wheat seedlings decreased at aniline test concentrations ranging between 25 and 200 mg L^-1. At 200 mg L^-1 aniline, the dry weight was only one-third that of the control group. Overall, the findings of this study provide evidence that aniline is a serious environmental pollutant causing deleterious genotoxic effects on wheat root tip cells and growth toxic effects on wheat seedlings. However, understanding the mechanisms that underlie aniline genotoxicity in plants needs further study.

The Application of Imaging Flow Cytometry to High-Throughput Biodosimetry

Biodosimetry methods, including the dicentric chromosome assay, the cytokinesis-block micronucleus assay and the γH2AX marker of DNA damage are used to determine the dose of ionizing radiation. These techniques are particularly useful when physical dosimetry is absent or questioned. While these assays can be very sensitive and specific, the standard methods need to be adapted to increase sample throughput in the case of a large-scale radiological/nuclear event. Recent modifications to the microscope-based assays have resulted in some increased throughput, and a number of biodosimetry networks have been, and continue to be, established and strengthened. As the imaging flow cytometer (IFC) is a technology that can automatically image and analyze processed blood samples for markers of radiation damage, the microscope-based biodosimetry techniques can be modified for the IFC for high-throughput biological dosimetry. Furthermore, the analysis templates can be easily shared between networked biodosimetry laboratories for increased capacity and improved standardization. This review describes recent advances in IFC methodology and their application to biodosimetry.

Cyclin E Deregulation and Genomic Instability

Precise replication of genetic material and its equal distribution to daughter cells are essential to maintain genome stability. In eukaryotes, chromosome replication and segregation are temporally uncoupled, occurring in distinct intervals of the cell cycle, S and M phases, respectively. Cyclin E accumulates at the G1/S transition, where it promotes S phase entry and progression by binding to and activating CDK2. Several lines of evidence from different models indicate that cyclin E/CDK2 deregulation causes replication stress in S phase and chromosome segregation errors in M phase, leading to genomic instability and cancer. In this chapter, we will discuss the main findings that link cyclin E/CDK2 deregulation to genomic instability and the molecular mechanisms by which cyclin E/CDK2 induces replication stress and chromosome aberrations during carcinogenesis.

Lanthanum nitrate genotoxicity evaluation: Ames test, mouse micronucleus assay, and chromosome aberration test

The increasing use of rare-earth elements (REE) and their compounds has led to their accumulation in the environment and has raised concern about their safety. The toxic effects of REE such as lanthanum are largely unknown; genotoxicity studies have been limited and results are controversial. We evaluated the genotoxicity of lanthanum nitrate (La(NO₃)₃) in several in vitro and in vivo tests, including bacterial reverse mutation assay (Ames test), mouse bone marrow micronucleus assay, and chromosome aberration assay. La(NO₃)₃ was not mutagenic in the Ames test. La(NO₃)₃ did not increase the frequencies of bone marrow micronuclei or chromosome aberration in the mouse after repeated treatments at oral doses up to 735 (females) and 855mg/kg (males). The compound did not increase the frequency of chromosome aberrations in CHO cells in vitro. These results indicate that lanthanum is not a genotoxic hazard.

Evaluation of genetic toxicity caused by acid mine drainage of coal mines on fish fauna of Simsang River, Garohills, Meghalaya, India

Fishery ecology of the Simsang River, Meghalaya is being threatened by large scale environmental degradation due to acid mine drainage (AMD) of coal mines. In the present paper, effort has been made to evaluate the genotoxicity caused due to AMD of coal mines on Channa punctata under laboratory condition through comet assay, micronucleus and chromosome aberration tests. Water samples were collected seasonally from affected and unaffected sites of the River and physico-chemical quality of water indicated low pH (4.6), high concentration of sulphates (270mgL(-1)) and iron (7.2mgL(-1)) beyond permissible limits. Polycyclic aromatic hydrocarbon (PAH) showed highest concentration of 4-ring PAH and Benzo[a]anthracene was the most important pollutant in the water collected from affected sites. The highest and the lowest mean concentrations of PAHs were estimated in monsoon and winter season, respectively. The index of DNA damage assessed by comet assay, micronucleus and chromosome aberration tests demonstrated significant differences season wise in different sampling sites. Frequency of DNA-damaged cells was found highest in the water samples collected from affected site in monsoon season.

Mutagenic properties of linuron and chlorbromuron evaluated by means of cytogenetic biomarkers in mammalian cell lines

Agricultural practices are usually supported by several chemical substances, such as herbicides. Linuron and chlorbromuron are phenylurea herbicides largely used to protect crops from weeds, blocking photosynthesis by inhibition of the photosystem II complex. The former, also commercially known as lorox or afalon, is selectively used to protect bean and French bean plants, fennels, and celeriacs; the second, commercially known as maloran, is selectively used for carrots, peas, potatoes, soy sprouts, and sunflowers. Considering the widespread use of herbicides and, more generally, pesticides, it is important to clarify their involvement on human health, one of them concerning the possible direct or indirect effect on the genome of exposed populations. Here, we show that these herbicides are endowed by mutagenic properties, as demonstrated by an increased number of chromosomal aberrations (CAs) in two exposed Chinese hamster cell lines derived from ovary and epithelial liver, respectively. This was also confirmed by sister chromatid exchange (SCE) and micronucleus (MN) assays. Our present and previously obtained data clearly indicate that phenylurea herbicides must be used with great caution, especially for agricultural workers who use large amounts of herbicides during their work, and particular attention should be given to residues of these herbicides and their involvement in environmental pollution.

Foundations of identifying individual chromosomes by imaging flow cytometry with applications in radiation biodosimetry

Biodosimetry is an important tool for triage in the case of large-scale radiological or nuclear emergencies, but traditional microscope-based methods can be tedious and prone to scorer fatigue. While the dicentric chromosome assay (DCA) has been adapted for use in triage situations, it is still time-consuming to create and score slides. Recent adaptations of traditional biodosimetry assays to imaging flow cytometry (IFC) methods have dramatically increased throughput. Additionally, recent improvements in image analysis algorithms in the IFC software have resulted in improved specificity for spot counting of small events. In the IFC method for the dicentric chromosome analysis (FDCA), lymphocytes isolated from whole blood samples are cultured with PHA and Colcemid. After incubation, lymphocytes are treated with a hypotonic solution and chromosomes are isolated in suspension, labelled with a centromere marker and stained for DNA content with DRAQ5. Stained individual chromosomes are analyzed on the ImageStream®^X (EMD-Millipore, Billerica, MA) and mono- and dicentric chromosome populations are identified and enumerated using advanced image processing techniques. Both the preparation of the isolated chromosome suspensions as well as the image analysis methods were fine-tuned in order to optimize the FDCA. In this paper we describe the method to identify and score centromeres in individual chromosomes by IFC and show that the FDCA method may further improve throughput for triage biodosimetry in the case of large-scale radiological or nuclear emergencies.

Cytogenetic and dosimetric effects of (131)I in patients with differentiated thyroid carcinoma: comparison between stimulation with rhTSH and thyroid hormone withdrawal treatments

A study directed to the cytogenetic and dosimetric aspects of radionuclides of medical interest is very valuable, both for an accurate evaluation of the dose received by the patients, and consequently of the genetic damage, and for the optimization of therapeutic strategies. Cytogenetic and dosimetric effects of (131)I in lymphocytes of thyroidectomized differentiated thyroid cancer (DTC) patients were evaluated through chromosome aberration (CA) technique: Euthyroid patients submitted to recombinant human thyroid-stimulating hormone (rhTSH) therapy (group A) were compared with hypothyroid patients left without levothyroxine treatment (group B). CA analysis was carried out prior to and 24 h, 1 week, 1 month and 1 year after radioiodine administration (4995-7030 MBq) in both groups. An activity-response curve of (131)I (0.074-0.740 MBq/mL) was elaborated, comparing dicentric chromosomes in vivo and in vitro in order to estimate the absorbed dose through Monte Carlo simulations. In general, radioiodine therapy induced a higher total CA rate in hypothyroid patients as compared to euthyroid patients. The frequencies of dicentrics obtained in DTC patients 24 h after treatment were equivalent to those induced in vitro (0.2903 ± 0.1005 MBq/mL in group A and 0.2391 ± 0.1019 MBq/mL in group B), corresponding to absorbed doses of 0.65 ± 0.23 Gy and 0.53 ± 0.23 Gy, respectively. The effect on lymphocytes of internal radiation induced by (131)I therapy is minimal when based on the frequencies of CA 1 year after the treatment, maintaining a higher quality of life for DTC patients receiving rhTSH-aided therapy.

Humoral deficiency in three paediatric patients with genetic diseases

BACKGROUND

Primary immunodeficiencies (PID) represent a heterogeneous group of genetic disorders characterised by poor or absent function in one or more components of the immune system. Humoral or antibody immunodeficiencies are the most common form of PID, of which common variable immunodeficiency (CVID) is the most frequent symptomatic form. CVID is usually characterised by hypogammaglobulinaemia with poor antibody specificity, and an increased susceptibility to infections, autoimmunity and lymphoproliferation. Fewer than 10% of CVID patients have a known monogenic basis. Several chromosomal abnormalities (chromosome 18q-syndrome, monosomy 22, trisomy 8 and trisomy 21) are currently identified as causes of hypogammaglobulinaemia, and can manifest with recurrent infections and mimic CVID.

METHODS

Review of clinical charts and laboratory results of paediatric patients followed in the outpatient clinic of PID with a diagnosis of genetic disease and humoral immunodeficiency.

RESULTS

Three patients with different genetic diseases (19p13.3 deletion, a ring 18 chromosome and Kabuki syndrome), were identified. During follow-up, they developed signs and symptoms suggestive of humoral deficiency mimicking CVID, despite which immunoglobulin levels were quantified with considerable delay with respect to symptoms onset, and specific management was subsequently delayed.

CONCLUSIONS

Patients with genetic abnormalities and recurrent infections should be evaluated for hypogammaglobulinaemia. An early diagnosis of humoral deficiency can allow treatment optimisation to prevent complications and sequelae.

Lymphocytes with multiple chromosomal damages in a large cohort of West Siberia residents: Results of long-term monitoring

Cells with specific multiple chromosome aberrations, defined as rogue cells (RC) have been described in different populations, predominantly those exposed to radiation. The frequency, etiology and related health risks have still not been elucidated due to their low frequency of occurrences and rarely performed studies. This study reports RC frequency using chromosome aberration (CA) assay in peripheral lymphocytes in the group of 3242 subjects, during a 30-year long follow-up study in a general rural and urban population, children environmentally exposed to radon, occupationally exposed population and lung cancer patients from the Kemerovo region (Siberia, Russian Federation). Results show that the highest RC frequency was present in children environmentally exposed to radon and the lowest in the general urban population. Total frequency of CA did not correlate with frequency of RC. Genotoxic analysis of air and water samples excluded anthropogenic pollution as a possible cause of genome damage and RC frequency. In 85% of RCs, double minutes, observed in a large number of human tumors, were present. Results of CA analysis suggested that radon and its decay products (alpha-emitters) were the leading factors causing RC in subjects exposed to high LET radiation. Thus, RC may be a candidate biomarker for exposure to this type of radiation.

Genotoxicity and cytotoxicity of copper oxychloride in cultured human lymphocytes using cytogenetic and molecular tests

The genotoxicity of copper oxychloride was investigated in human lymphocytes using chromosome aberration (CA) and micronucleus (MN) tests and the randomly amplified polymorphic DNA-polymerase chain reaction technique. The lymphocytes were treated with 3, 6, and 12 µg/mL of copper oxychloride for 24 and 48 h. Copper oxychloride increased CA and abnormal cells in a dose-dependent manner. The frequency of MN and micronucleated binuclear cells also increased at all concentrations and treatment periods. However, copper oxychloride cytotoxicity, observed through lower mitotic and nuclear division index, was significantly lower only at the higher concentrations (6 and 12 µg/mL). Copper oxychloride increased the polymorphic bands and decreased genomic template stability. In conclusion, in this study it was confirmed that copper oxychloride has genotoxic potential for human lymphocytes in vitro. Additionally, caution is advised for its use as a fungicide, because it may increase the risk of exposure through the food chain.

Mutagenicity of two herbicides widely used on soybean crops by the Allium cepa test

This study evaluated the mutagenic effects of two herbicides: Clorimurom Nortox(®) and Imazaquim Ultra Nortox(®) widely used on soybean crops in Brazil. As a test system, Allium cepa assay was used, which analyzes the frequency of micronuclei (MN), chromosomal aberrations (CA) and the mitotic index (MI). Four concentrations of each herbicide (50, 75, 100 and 125 %) were tested in triplicate using distilled water (negative control) and methyl methanesulfonate (positive control) as controls. Three experimental repetitions were realized. Clorimurom Nortox(®) showed a significantly lower MI than the negative control for the concentrations of 75, 100 and 125 %, but the CA was significantly increased at all concentrations. There was no recovery for CA or MI. The 125 % concentration of Imazaquim Ultra Nortox(®) was cytotoxic and also exerted an effect on the other parameters. The concentration of 100 % showed a statistically increased MN and there was no recovery, while the 75 % concentration significantly affected CA, with recovery observed. The two herbicides showed mutagenic damage in Allium cepa cells, which implies a careful handling of these products, to minimize the risk of human and environmental contamination.

A study of professional radiation hazards in CT scan and nuclear medicine workers using GTG-banding and solid stain

BACKGROUND

CT scan and nuclear medicine exams deliver a great part of medical exposures. This study examined professional radiation hazards in CT scan and nuclear medicine workers.

METHODS

In a cross sectional study 30 occupationally exposed workers and 7 controls (all from personnel of a laboratory) were selected. Physical dosimetry was performed for exposed workers. Blood samples were obtained from the experimental and control groups. Three culture mediums for each one were prepared in due to routine chromosome analysis using G-banding and solid stain.

RESULTS

There were significant increased incidence of chromatid gap (ctg) and chromatid break (ctb) with mean±SD frequencies of 3±0.84 and 3.1±1.40 per 100 cells respectively in the nuclear medicine workers versus controls with mean±SD frequencies of 1.9±0.69 and 1.3±0.84 for ctg and ctb, respectively. Chromosome gaps (chrg) were higher significantly in the nuclear medicine population (2.47±0.91) than in controls (1.4±0.9) (p< 0.05). In CT scan group the ctg and ctb were increased with a mean±SD frequency of 2.7±0.79 and 2.6±0.91 per 100 cells respectively compared with control group. The mean±SD frequencies of the chrb were 2.0±0.75 and 0.86±0.690 per 100 cells for exposed workers and control group, respectively.

CONCLUSION

This study showed chromosome aberrations in peripheral lymphocytes using solid stain method are reasonable biomarker reflecting personnel radiation damage.

Translocation t(3;12)(q26;q21) in JAK2(V617F) Point Mutation Negative Chronic Idiopathic Myelofibrosis: A Case Report

The myeloproliferative diseases (MPDs) or myelo-proliferative neoplasms (MPNs) are a group of diseases of the bone marrow in which excess cells are produced. Chronic idiopathic myelofibrosis (CIMF) is a stem cell defect characterized by splenomegaly with multiorgan extramedullary hematopoiesis, immature peripheral blood granulocytes and erythrocytes and progressive bone marrow fibrosis. The most common chromosomal abnormalities seen in CIMF patients include numerical changes of chromosomes 7, 8 and 9, and structural changes of 1q, 5q, 13q and 20q. At least 75.0% of patients with bone marrow abnormalities have one or more of these chromosomal anomalies. Detection of the Janus kinase 2 (JAK2) mutation may be a potential major breakthrough for understanding the pathobiology of MPNs, and is an essential part of the diagnostic algorithm. In this study, we describe a JAK2(V617F) mutation negative CIMF patient who has the chromosomal translocation t(3;12)(q26;q21) in her karyotype.

In vitro genotoxicity assessment of the synthetic plant growth regulator, 1-naphthaleneacetamide

1-Naphthaleneacetamide (NAAm) is a synthetic plant growth regulator in the auxin family that is widely used in agriculture to promote the growth of numerous fruits, for root cuttings and as a fruit thinning agent. The potential genotoxic effects of NAAm were investigated in vitro by the chromosome aberrations (CAs), and cytokinesis-block micronucleus assays in human peripheral blood lymphocytes (PBLs) for the first time. The human PBLs were treated with 20, 40, 80, and 160 µg/mL of NAAm for 24 and 48 h. The results of this study showed that NAAm significantly induced the formation of structural CA and MN for all concentrations (20, 40, 80 and 160 µg/mL) and treatment periods (24 and 48 h) when compared with the negative and the solvent control. In addition, the higher concentrations of NAAm (80 and 160 µg/mL) caused a statistically significant increase in nuclear bud (NBUD) formation for both 24 and 48 h treatment times. With regard to the cell cycle kinetics, at all the tested concentrations, NAAm caused a statistically significant reduction in the mitotic index (MI) only for 48 h treatment period and also in the nuclear division index (NDI) for both 24 and 48 h treatment periods as compared to the control groups. The reductions in the MI and NDI occured in a concentration-dependent manner for both treatment times. In conclusion, the present results indicate that in the tested experimental conditions, NAAm was genotoxic and cytotoxic on human PBLs in vitro.

Determination of genotoxic effects of Imazethapyr herbicide in Allium cepa root cells by mitotic activity, chromosome aberration, and comet assay

Imazethapyr (IM) is an imidazolinone herbicide that is currently used for broad-spectrum weed control in soybean and other legume crops. In this study, cytotoxic and genotoxic effects of IM were investigated by using mitotic index (MI), mitotic phases, chromosomal abnormalities (CAs) and DNA damage on the root meristem cells of Allium cepa. In Allium root growth inhibition test, EC50 value was determined as 20 ppm, and 0.5xEC50, EC50 and 2xEC50 concentrations of IM herbicide were introduced to onion tuber roots. Distilled water and methyl methane sulfonate (MMS, 10 mg/L) were used as a negative and positive control, respectively. As A. cepa cell cycle is 24 hours, so, application process was carried out for 24, 48, 72 and 96 hours. All the applied doses decreased MIs compared to control group and these declines were found to be statistically meaningful. Analysis of the chromosomes showed that 10 ppm IM except for 48 h induced CAs but 40 ppm IM except for 72 h decreased CAs. DNA damage was found significantly higher in 20 and 40 ppm of IM compared to the control in comet assay. These results indicated that IM herbicide exhibits cytotoxic activity but not genotoxic activity (except 10 ppm) and induced DNA damage in a dose dependent manner in A. cepa root meristematic cells.

Safety evaluation of a triazine compound nitromezuril by assessing bacterial reverse mutation, sperm abnormalities, micronucleus and chromosomal aberration

Nitromezuril (NZL) is a novel triazine compound that exhibits remarkable anticoccidial activity. However, mutagenicity and genotoxicity of NZL have not been evaluated to date. This study evaluated the potential risks of NZL by testing for bacterial reverse mutation (Ames), mouse sperm abnormality (SA), bone marrow micronucleus (MN) and chromosomal aberration (CA). Mice were orally administered with NZL at 385, 192 and 96 mg/kg, corresponding to 0.5 ×, 0.25 × and 0.125 × the LD50 of NZL, respectively. No significant increases in SA and CA were found in mice treated with NZL for 5d and 3d, respectively (P>0.05). NZL at 96-385 mg/kg did not have significant influence on micronucleated polychromatic erythrocyte counts (P>0.05). These results suggest that NZL is not genotoxic. However, Ames test results were positive both with and without the S9 system for Salmonella typhimurium TA98 and TA100, suggesting that NZL may be mutagenic. The mutagenic effects of NZL were different in in vitro and in vivo assays. Further studies should be conducted to confirm the safety of using and developing NZL as a novel anticoccidial drug.

Evaluation of chromosomal aberrations caused by air pollutants in some taxi drivers from two polluted districts of urban Tehran and its comparison with drivers from rural areas of Lahijan: a pilot study

BACKGROUND

Chromosome instability is the most common form of genomic instability. Genomic instability can lead to tumorogenesis. High level of chromosomal aberrations in peripheral blood lymphocytes can be used as a biomarker for cancer. Air pollution is one of the most important factors that cause chromosomal instability (CIN). In this comparative study we used classic Cytogenetic technique to analyze the effects of air pollutants on chromosome stability. We collected peripheral blood from 30 taxi drivers of two polluted districts (districts 6 and 7) in Tehran and 30 taxi drivers from rural areas of Lahijan, north of Iran.

RESULTS

Comparison of the level of chromosome breakage in the two groups showed an increased level of chromosome breakage in the drivers from polluted districts of Tehran, although not significant, using Fisher exact test (p-value = 0.300). However, the overall chromosome aberration rate (including both chromosome and chromatid gaps), the difference was significant using Chi-square test (p-value = 0.012).

CONCLUSION

An increased level of chromosome aberration was present in the drivers from polluted districts of Tehran compared to drivers from non-polluted areas in Lahijan.

Cytotoxicity and genotoxicity of butyl cyclohexyl phthalate

Butyl cyclohexyl phthalate (BCP) is frequently used in personal care products, medical and household applications. The aim of this study is therefore to evaluate possible cytotoxicity and genotoxicity of BCP using in vitro and in vivo assays. The in vitro cytotoxic effect of BCP was investigated on mouse fibroblastic cell line (L929 cells) by MTT assay. The result showed that BCP inhibits cell proliferation in a concentration-dependent manner (IC50 value = 0.29 µg/mL). For genotoxicity assessment, tested concentrations of BCP demonstrated mutagenic activity in the presence of S9 mix with the Salmonella strain TA100 in the Ames test. Results showed that BCP is a secondary mutagenic substance even in low concentrations. The data obtained from 28-days repeated toxicity tests on mice revealed that BCP caused abnormalities of chromosome number, in a dose-dependent manner. Additionally, DNA damage, particularly DNA strand breaks, was assessed by Comet assay. The test result shows that BCP seemed to have genotoxic potential at a high level of exposure.

Evaluation of vinyl laurate in a battery of in vitro and in vivo tests for genotoxicity

Vinyl laurate is a potential residual monomer in chewing gum base formulated with polyvinyl acetate vinyl laurate copolymer (PVAcVL). The genotoxic potential of vinyl laurate was examined in a battery of in vitro and in vivo genotoxicity tests. Vinyl laurate was not mutagenic in Ames tests. In addition, it was not mutagenic in the HPRT mutation assay in L5178Y cells. An in vitro mammalian chromosome aberration assay performed in CHO cells was equivocal. Vinyl laurate and/or its metabolites were not clastogenic in the mouse bone marrow micronucleus test. Kinetic data indicate that VL is metabolised to acetaldehyde and lauric acid. Both metabolites are well known and have been studied previously. Model calculations show, that any exposure to acetaldehyde from the consumption of PVAcVL containing chewing gum will remain far below levels of acetaldehyde exposure from food in which acetaldehyde occurs naturally. Direct exposure to VL will primarily be at the site of entry. The lack of toxicity in a 90-day repeated dose toxicity test, performed with VL doses up to approximately 3000 times higher than the maximal VL intake from the consumption of a typical piece of chewing gum, demonstrates a high safety margin.

Activation of Toll-like receptors by intestinal microflora reduces radiation-induced DNA damage in mice

Activation of Toll-like receptors (TLRs) signaling by intestinal microflora-derived bacterial products plays a key role in injury defence for the host. We investigated the role of TLRs activated by intestinal microflora in radiation-induced DNA damage in mice. We analyzed DNA damage induced by 2Gy γ-ray radiation in an intestinal commensal bacteria-depleted mouse model (CD group), in which TLRs (TLR2/6, TLR4 and TLR5) ligand levels in serum were reduced. Chromosomal aberrations were measured in bone marrow cells and peripheral blood leukocyte comet assays were performed. DNA damage was increased in the CD group compared with the control group. Treatment of mice with TLR agonists (CBLB502, LPS and lipopeptide) 1h before radiation resulted in a significant decrease in DNA damage. Genes induced by TLR5 activation were analyzed; activation of TLRs regulated the expression of Gadd45b, Sod2, and Rad21, which are involved in DNA damage repair. In summary, our data indicate that TLRs activation by intestinal microflora reduces DNA damage induced by radiation and regulates expression of several DNA repair genes.

Titanium Dioxide Nanoparticles are not Cytotoxic or Clastogenic in Human Skin Cells

The application of nanoparticle technology is rapidly expanding. The reduced dimensionality of nanoparticles can give rise to changes in chemical and physical properties, often resulting in altered toxicity. People are exposed dermally to titanium dioxide (TiO₂) nanoparticles in industrial and residential settings. The general public is increasingly exposed to these nanoparticles as their use in cosmetics, sunscreens and lotions expands. The toxicity of TiO₂ nanoparticles towards human skin cells is unclear and understudied. We used a human skin fibroblast cell line to investigate the cytotoxicity and clastogenicity of TiO₂ nanoparticles after 24 h exposure. In a clonogenic survival assay, treatments of 10, 50 and 100 μg/cm₂ induced 97.8, 88.8 and 84.7% relative survival, respectively. Clastogenicity was assessed using a chromosomal aberration assay in order to determine whether TiO₂ nanoparticles induced serious forms of DNA damage such as chromatid breaks, isochromatid lesions or chromatid exchanges. Treatments of 0, 10, 50 and 100 μg/cm₂ induced 3.3, 3.0, 3.0 and 2.7% metaphases with damage, respectively. No isochromatid lesions or chromatid exchanges were detected. These data show that TiO₂ nanoparticles are not cytotoxic or clastogenic to human skin cells.

Tobacco dust induced genotoxicity as an occupational hazard in workers of bidi making cottage industry of central India

CONTEXT

To explore genotoxicity in bidi rollers occupationally exposed to bidi tobacco dust.

AIMS

To assess the extent of genotoxicity of tobacco dust to bidi rollers of Jabalpur, Madhya Pradesh, India and cytotoxicity of bidi tobacco extract.

SETTINGS AND DESIGN

Blood samples from 31 bidi rollers and 30 controls taken after written informed consent were analyzed for chromosome aberrations (CA) and comet assay.

MATERIALS AND METHODS

Genotoxicity was studied by CA in cultured peripheral blood lymphocytes of bidi rollers and the deoxyribonucleic acid (DNA) damage studies were done by comet assay of their blood. The toxicity of bidi tobacco extract to normal human lymphocytes was studied by MMT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay as drop in viability.

STATISTICAL ANALYSIS USED

Student's t-test and DMRT.

RESULTS

There is a general trend of increase in CA% of both in exposed and control groups with age, but in every group the bidi rollers have a significantly higher CA% than the controls. The CA % is also directly related to exposure. The comet assay findings reveal that the mean comet length and tail length increases with exposure time. The toxicity of bidi tobacco extract (TE) to normal human lymphocytes was tested in vitro by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay at 2 h of incubation. The trend of drop in viability with increasing concentrations of TE was clearly evident from the data from four donors in spite of their individual differences in viability.

CONCLUSIONS

The results obtained in this investigation indicate that bidi rollers seem to be facing the occupational hazard of genotoxicity due to handling bidi tobacco and inhalation of tobacco dust. They should be advised to work under well-ventilated conditions.

Nicotine derived genotoxic effects in human primary parotid gland cells as assessed in vitro by comet assay, cytokinesis-block micronucleus test and chromosome aberrations test

Genotoxic effects of nicotine were described in different human cells including salivary gland cells. Based on the high nicotine concentration in saliva of smokers or patients using therapeutic nicotine patches, the current study was performed to evaluate the genotoxic potential of nicotine in human salivary gland cells. Therefore, primary salivary gland cells from 10 patients undergoing parotid gland surgery were exposed to nicotine concentrations between 1 μM and 1000 μM for 1 h in the absence of exogenous metabolic activation. The acinar phenotype was proven by immunofluorescent staining of alpha-amylase. Genotoxic effects were evaluated using the Comet assay, the micronucleus test and the chromosome aberration test. Cytotoxicity and apoptosis were determined by trypan blue exclusion test and Caspase-3 assay. Nicotine was able to induce genotoxic effects in all three assays. The chromosome aberration test was the most sensitive and increases in numerical and structural (chromatid-type and chromosome-type) aberrations were seen at ≥1 μM, whereas increases in micronuclei frequency were detected at 10 μM and DNA damage as measured in the Comet assay was noted at >100 μM. No cytotoxic damage or influence of apoptosis could be demonstrated. Nicotine as a possible risk factor for tumor initiation in salivary glands is still discussed controversially. Our results demonstrated the potential of nicotine to induce genotoxic effects in salivary gland cells. These results were observed at saliva nicotine levels similar to those found after oral or transdermal exposure to nicotine and suggest the necessity of careful monitoring of the use of nicotine in humans.

Investigation of cytotoxic and genotoxic effects of the antihistaminic drug, loratadine, on human lymphocytes

CONTEXT

Loratadine (LOR) is a new generation antihistamine used in the treatment of allergic disorders.

OBJECTIVE

The aim of this study was to evaluate the cytogenotoxic effect of LOR on human peripheral blood lymphocytes.

MATERIALS AND METHODS

We investigated the genotoxic effect of this drug in cultured human peripheral blood lymphocytes using sister chromatid exchange (SCE), chromosomal aberrations (CA) and micronucleus (MN) assay in culture conditions. Proliferation index (PI), mitotic index (MI) and nuclear division index (NDI) were also calculated to determine the cytotoxic/cytostatic effect. Cultures were treated with LOR at three concentrations (5, 15 and 25 µg/ml) for 48 h.

RESULTS

Although the MI significantly decreased at the higher concentrations (15 and 25 µg/ml) compared with negative (solvent) control, LOR indicated weaker cytotoxic potential in PI and NDI values at all the tested concentrations. LOR increased the frequencies of SCE, CA and MN in all lymphocyte cultures. However, significant increase was observed in MN at the medium and highest doses (15 and 25 µg/ml) and in CA at the medium dose (15 µg/ml) compared with negative (solvent) control culture. Our results indicate that LOR has cytotoxic and genotoxic effects on human peripheral blood lymphocyte cultures.

DISCUSSION

Although most of previously findings have shown that LOR does not reflect genotoxicity, our results indicated that it may be a genotoxic drug.

CONCLUSION

More studies are necessary to elucidate the relationship between cytotoxic, genotoxic and apoptotic effects, and to make a possible risk assessment in patients receiving therapy with this drug.

Arsenic is cytotoxic and genotoxic to primary human lung cells

Arsenic originates from both geochemical and numerous anthropogenic activities. Exposure of the general public to significant levels of arsenic is widespread. Arsenic is a well-documented human carcinogen. Long-term exposure to high levels of arsenic in drinking water has been linked to bladder, lung, kidney, liver, prostate, and skin cancers. Among them, lung cancer is of great public concern. However, little is known about how arsenic causes lung cancer and few studies have considered effects in normal human lung cells. The purpose of this study was to determine the cytotoxicity and genotoxicity of arsenic in human primary bronchial fibroblast and epithelial cells. Our data show that arsenic induces a concentration-dependent decrease in cell survival after short (24h) or long (120h) exposures. Arsenic induces concentration-dependent but not time-dependent increases in chromosome damage in fibroblasts. No chromosome damage is induced after either 24h or 120h arsenic exposure in epithelial cells. Using neutral comet assay and gamma-H2A.X foci forming assay, we found that 24h or 120h exposure to arsenic induces increases in DNA double strand breaks in both cell lines. These data indicate that arsenic is cytotoxic and genotoxic to human lung primary cells but lung fibroblasts are more sensitive to arsenic than epithelial cells. Further research is needed to understand the specific mechanisms involved in arsenic-induced genotoxicity in human lung cells.

Low concentration of exogenous carbon monoxide protects mammalian cells against proliferation induced by radiation-induced bystander effect

Radiation-induced bystander effect (RIBE) has been proposed to have tight relationship with the irradiation-caused secondary cancers beyond the irradiation-treated area after radiotherapy. Our previous studies demonstrated a protective effect of low concentration carbon monoxide (CO) on the genotoxicity of RIBE after α-particle irradiation. In the present work, a significant inhibitory effect of low-dose exogenous CO, generated by tricarbonyldichlororuthenium (II) dimer [CO-releasing molecule (CORM-2)], on both RIBE-induced proliferation and chromosome aberration was observed. Further studies on the mechanism revealed that the transforming growth factor β1/nitric oxide (NO) signaling pathway, which mediated RIBE signaling transduction, could be modulated by CO involved in the protective effects. Considering the potential of exogenous CO in clinical applications and its protective effect on RIBE, the present work aims to provide a foundation for potential application of CO in radiotherapy.