Number Of Sister Chromatid Exchanges Research Articles

Survival analysis and associated factors of highgrade glioma patients

High-grade gliomas are the most common primary brain tumors in adults, and they usually have a quick fatal course. Average survival is 18 months, mainly, because of tumor resistance to Stupp protocol. To determine high-grade glioma patient survival and the effect of persuasion variables on survival. We conducted a longitudinal descriptive study in which 80 untreated recently diagnosed high-grade glioma patients participated. A survey was conducted regarding their exposure to some risk factors, degree of genetic instability in peripheral blood using micronucleus quantification on binuclear lymphocytes, micronuclei in reticulocytes and sister-chromatid exchanges in lymphocytes. In the statistical analysis, this study constructed life tables, used the Kaplan-Meier, and the log-rank test, and in the multivariate analysis, a Cox proportional hazards model was constructed. Eighty patients' clinical, demographic and lifestyle characteristics were analyzed, as well as their survival rates and the average survival time is 784 days (interquartile range: 928). Factors like age, exposure at work to polycyclic hydrocarbons and the number of sister-chromatid exchanges in lymphocytes in the first sampling was significantly survivalrelated in the multivariate analysis. We determined that only three of the analyzed variables have an important effect on survival time when it comes to high-grade glioma patients.

Assessment of the genotoxic effects of antihypertensive drug active ingredient indapamide in human lymphocytes

Hypertension is the most common cardiovascular disease and is also known as high blood pressure. The large majority of hypertensive patients need long-term administration of antihypertensive agents. Indapamide is an orally administered diuretic antihypertensive drug. The present work aimed to assess the possible genotoxic effects of indapamide using four different assays: chromosomal aberration (CA), sister chromatid exchange (SCE), micronucleus (MN), and comet. Lymphocytes from three different donors were exposed to 18.75, 37.50, 75.00, and 100.00 μg/ml indapamide. Additionally, a negative, a positive (mitomycin C = MMC, 0.20 μg/ml), and a solvent control (5.4 μl/ml methanol) were also applied. As a result, it was seen that indapamide did not cause a significant change in CAs and MN frequencies compared to the control. It caused significant damage only at the highest concentration in the comet assay. Similarly, while it did not affect the number of SCEs in the 24-h treatment, it increased the SCE frequency at the two highest concentrations in the 48-h. Mitotic index (MI) decreased at almost all concentrations. Considering all these results, this study revealed that indapamide did not have a significant genotoxic effect in these conditions. To the best of our knowledge, this is the first investigation about the genotoxic effect of indapamide in human lymphocytes in vitro.

Genotoxicity induced in vitro by water-soluble indoor PM2.5 fractions in relation to heavy metal concentrations.

The aim of the present study was to examine the genotoxicity induced by water-soluble fractions of particulate matter (PM) and its potential relation with heavy metals. For this purpose, the genotoxicity induced on human peripheral lymphocytes by water-soluble PM2.5 (particles with aerodynamic diameter ≤ 2.5μm) collected from the indoor air of various workplaces in Greece (n= 20), was examined by the Sister Chromatid Exchange (SCE) induction assay and assessed in relation to the concentrations of the heavy metals Cu, Pb, Mn, Ni, Co, Zn, Cr, and Cd. The number of SCEs per metaphase (SCEs/metaphase), as an indicator of genotoxicity, the proliferation rate index (PRI), as an indicator of cytostaticity, and the mitotic index (MI), as an indicator of cytotoxicity, were measured and assessed in three water-soluble fractions of PM2.5: the total water-soluble fraction WSA (filtered through 0.45μm), the dissolved fraction WSB (filtered through 0.22μm), and the non-chelexed dissolved fraction WSC (filtered through Chelex-100 resin). Results showed statistically significant number of SCEs/metaphase in all water-soluble PM2.5 fractions in relation to the control with large variabilities across the workplaces as a result of variations in indoor conditions, sources, and/or activities. The concentrations of genotoxicity were evaluated in terms of mass-normalized genotoxicity (SCEs/mg PM2.5), that represents the genotoxic potency of particles, and air volume-normalized genotoxicity (SCEs/m3 air), that reflects the inhalation risk for people working or spending much time in these microenvironments. Correlation and linear regression analyses were further employed in order to investigate the potential relationships between genotoxicity and the water-soluble concentrations of PM2.5-bounded heavy metals. According to the results, the highest mass-normalized genotoxicity values were found for PM2.5 from the photocopying center, whereas the highest air volume-normalized genotoxicity was found in tavern-2. Significant positive correlations between the genotoxicity and water-soluble metals were derived, highlighting the role that heavy metals play in the genotoxicity of indoor PM2.5. Among the targeted metals, Zn and Pb were found to be good predictors of the genotoxicity of water-soluble PM2.5.

In vitro and in vivo evaluation of clastogenicity of second-line antitubercular drug loaded PLGA nanoparticles.

Sustained release nanoformulations of second line antitubercular drugs levofloxacin and ethionamide had shown promise in pharmacokinetics and acute and sub-acute toxicity studies. The present study evaluated the clastogenicity potential of the nanoformulations of these antitubercular agents. Clastogenicity was evaluated by (a) in vitro micronucleus assay (b) in vivo micronucleus assay in Swiss albino mice and (c) sister chromatid exchange (SCE) in CHO cell lines. Ethionamide and levofloxacin loaded nanoparticles were 312 ± 64 nm and 245 ± 24 nm in size respectively and drug encapsulation was 35.2 ± 3.1% w/w and 45.6 ± 9.4% w/w, respectively. The frequency of MN-NCE/1000 NCE and MN-PCE/1000 PCE were significantly reduced in mice treated with ethionamide nanoparticle (3.5 ± 0.9, 13.8 ± 16.68) and levofloxacin nanoparticles (5.6 ± 2.7, 16.7 ± 12.7) compared to the mice treated with free ethionamide (11.5 ± 4.1, p = 0.23 and 45.19 ± 19.21, p = 0.38) and free levofloxacin (14.7 ± 1.88, p < 0.0001 and 54.6 ± 18.1, p = 0.0017), respectively. For in vitro, micronucleus assay frequencies of micronuclei per thousand bi-nucleated cells (MN-BN/1000 BN) was 188.3 ± 20.20 and 148 ± 20.42 for ethionamide and levofloxacin nanoparticles as compared to 232.6 ± 16.04 (p = 0.52) and 175 ± 5.56 (p = 0.45) for free ethionamide and levofloxacin, respectively. The average number of SCE per cell for nanoformulation of ethionamide were not different from that of free drug (4.9 ± 0.51 vs 4.1 ± 0.55, p = 0.86). The SCE per cells were not significant difference for nanoformulation of levofloxacin (2.33 ± 1.36 vs 5.46 ± 0.25, p = 0.88). In vitro and in vivo assays have shown relatively less clastogenic potential of equivalent dose of ethionamide nanoparticles as compared to the conventional formulation.

Vitamin E protects against cisplatin-induced genotoxicity in human lymphocytes

Cisplatin is an anticancer drug that is widely used in treatments of human malignancies such as ovaries,’ testes,’ and solid tumors of the head and neck. However, the use of cisplatin in the treatments can be associated with DNA damage and high risk to the development of secondary malignancies. Vitamin E is a strong lipophilic antioxidant that has the ability to protect normal cells from chromosomal damage and promote the repair of the damaged DNA. In the current study, the possible protective effect of vitamin E on DNA damage induced by cisplatin was investigated. For that, chromosomal aberrations (CAs) frequency and the number of sister chromatid exchanges (SCEs) were measured in cultured human lymphocytes. Results showed that cisplatin statistically significant increases in the number of cells with CAs (P < 0.05) and in the frequency of SCEs (P < 0.05) as compared to the control group. These increases were significantly lowered by pretreatment of cells with vitamin E. Additionally, cisplatin reduced mitotic index at used concentrations (P < 0.05), which was normalized by vitamin E. Therefore, we conclude that vitamin E can prevent the genotoxicity of cisplatin on cultured human lymphocyte.

Conjunction of the molecular, cytogenetic and genetic biomarkers as predictor of vulnerability to medical radiation treatment

In previously reported studies of healthy controls, prostate cancer patients, and thyroid disease patients, exposed diagnostically to I-131, voluntarily obtained blood samples, or isolated lymphocytes were exposed in vitro to high challenging dose of X-rays. Before and right after in vitro irradiation; the DNA Repair Competence Assay and cytogenetic methods were applied. Strong variability between individual vulnerability to radiation was reported. For this investigation, using PCR method the XRCC1(194) and XRCC1(399), that are engaged in base excision and DNA single strand breaks repair, and XRCC3(241) involved in DNA double strand breaks repair via homologous recombination, were investigated in randomly chosen samples from 60 subjects. Results of investigated biomarkers stratified according conjunction of polymorphic alleles have shown insignificant variability between all subjects in the DNA sensitivity to irradiation, detected immediately after challenging exposure in 40 °C. In contrast, high differences are observed between subgroups stratified according conjunction of polymorphic alleles of investigated genes, in levels of biomarkers related to DNA repair (DNA RCA and percentage of cells with significantly elevated number of sister chromatid exchanges) as well as biomarkers of cancer risk. One of the highest percentage of not repaired DNA damage evaluated by the DNARCA, and frequency of chromosome aberration, were detected in lymphocytes of prostate cancer patient with homozygous genotype at XRCC3-241/C and XRCC1-194/C, and heterozygous at XRCC1-399A/G locus. Obtained results confirm strong influence of genotypes on the repair efficiency of DNA damage induced by irradiation and levels of biomarkers that are predictor of cancer risk.

Protective role of eugenol on arsenic induced oxidative DNA damage and modulatory effect of GSTO2 polymorphism

Arsenic exposure is one of the major health problem worldwide. It is related with various cancers and numerous other pathological effects. The present work was aimed to study the ameliorative effects of eugenol against arsenic mediated oxidative DNA damage using Sister chromatid exchanges (SCE), comet, and lipid peroxidation assays as biomarkers. For the genotyping of GSTO2, PCR RFLP method was used. The treatment with sodium arsenite showed dose dependent increase in frequency of SCE, comet tail moment (Tm), and lipid peroxidation (TBARS levels). On administration of eugenol (10 and 20 µM) significant dose dependent decrease in the number of SCE, Tm value, and TBARS levels observed in arsenic treated cultured peripheral blood lymphocytes. Nonsignificant effects of GSTO2 polymorphism perceived on arsenic genotoxicity and eugenol antigenotoxicity. The results of the present work suggest a protective role of eugenol against arsenic induced genotoxic and oxidative damage in cultured human peripheral blood lymphocytes. Practical application Arsenic contamination of groundwater is one of the leading environmental issues worldwide. Chronic exposure of arsenic cause several health problems including tumor manifestation. The results of the present study suggest the use of indigenous dietary elements, herbs, shrubs as a safer and effective preventative medicine against heavy metal induced genotoxicity and oxidative stress.

Investigation of genotoxic effects of paraben in cultured human lymphocytes

Paraben is a phenolic derivative of benzoic acid extensively used as preservatives in food, pharmaceutical, and cosmetic industries due to its antimicrobial characteristics. The objective of this study was to evaluate the in vitro genotoxic effects of paraben in human lymphocyte cultures. Cells were analyzed by cytokinesis-block micronucleus (CBMN), chromosome aberration (CA), sister chromatid exchange (SCE), and comet tests. For CBMN, CA, and SCE assays, the human lymphocytes were isolated from healthy donors and incubated with 500, 250, 100, and 50 µg/mL of paraben for 24 and 48 h, and for comet assay, cells were exposed to 1000, 750, 500, and 250 µg/mL of paraben for an hour. Results showed that numbers of MN and SCEs were not significant in the cells exposed to paraben when compared to the solvent control. However, 500 and 250 µg/mL of paraben induced the CA after 24 h. Also, we observed a significant decrease in the cytokinesis-block proliferation index in cells exposed 250–500 µg/mL paraben for 24 h, and 100, 250, and 500 µg/mL for 48 h. The mitotic index was also decreased at all concentrations and periods. However, the proliferation index was statistically decreased at all concentrations after 48 h treatments. Only the highest concentration of paraben caused DNA migration (mean tail length) in human lymphocytes analyzed by Comet assay. Taken together, results indicated that paraben had cytotoxic effects and caused genotoxicity by affecting directly chromosomes and DNA in human lymphocyte cells in vitro, and may have genotoxic potential for human.

Genotoxic effects of Roundup Full II® on lymphocytes of Chaetophractus villosus (Xenarthra, Mammalia): In vitro studies.

In Argentina, Chaetophractus villosus has a wide distribution that overlaps with agricultural areas where soybean is the predominant crop. In such areas the pesticide Roundup Full II® (RU) is widely applied. The genotoxic effect of its active ingredient glyphosate (RU is 66.2% glyphosate) on the peripheral blood lymphocytes of C. villosus was tested over a range of concentrations (280, 420, 560, 1120 μmol/L). Culture medium without glyphosate served as negative control, while medium containing mitomycin C served as positive control. Genetic damage was characterized in terms of the percentage of cells with chromosome aberrations (CA), the mean number of sister chromatid exchanges (SCE) per cell, and the modification of cell proliferation kinetics via the calculation of the replication index. Significant increases (p < 0.0001) were seen in the CA frequency and the mean number of SCEs per cell compared to negative controls at all the RU concentrations tested. Chromatid breaks, the only form of CA observed, under the 560 μmol/L RU conditions and in presence of mitomycin C were four to five times more common than at lower concentrations, while no viable cells were seen in the 1120 μmol/L treatment. The mean number of SCEs per cell was significantly higher under the 280 μmol/L RU conditions than the 420 or 560 μmol/L RU conditions; cells cultivated in the presence of MMC also showed significantly more SCEs. All the RU concentrations tested (except in the 1120 μmol/L RU treatment [no viable cells]) induced a significant reduction in the replication index (p < 0.0001). The present results confirm the genotoxic effects of RU on C. villosus lymphocytes in vitro, strongly suggesting that exposure to RU could induce DNA damage in C. villosus wildlife.

Genotoxic Evaluation of Duloxetine II. The Effect on the Number of Sister Chromatid Exchanges, the Mitotic Index, and the Proliferation Kinetics in Mouse Bone Marrow.

Duloxetine is an antidepressant which has showed valuable results, particularly in patients with major depression. This type of drugs is known to require genotoxic studies as part of their preclinical safety evaluation. In the case of duloxetine, however, there have been controversial results. Therefore, we considered it worthwhile to extend studies on the matter in an attempt to reach a conclusion. The present assay was made in mouse bone marrow to evaluate the capacity of the drug to induce sister chromatid exchanges (SCE), as well as to modify the proliferation kinetics and the mitotic index. Three doses of the antidepressant were tested (2, 20, and 200 mg/kg), besides the control mice were administered with purified water, and the positive treated animals administered with 1 mg/kg of doxorubicin. The results indicated a moderate but significant increase of SCE with the three tested doses, no effect regarding the mitotic index and a small reduction in the proliferation kinetics. Although in our assay the drug showed a lower effect, the present study agreed with a previous report that analyzed the amount of micronuclei in mouse peripheral blood, and it confirmed the relevance of evaluating the genotoxic effect of antidepressants, specifically duloxetine by applying diverse tests.

Retrospective Biological Dosimetry at Low and High Doses of Radiation and Radioiodine Impact on Individual Susceptibility to Ionizing Radiation.

Iodine-131 (I-131) is often used in thyroid diagnostics and therapy. External and internal exposure to radioiodine can lead to molecular and cellular damage in peripheral blood lymphocytes. The aim of this study was to explore the influence of low and high doses of I-131 on susceptibility to ionizing radiation. Study groups consisted of 30 individuals free of thyroid diseases, 41 patients exposed diagnostically to low doses of I-131, and 37 hyperthyroidism patients exposed therapeutically to high doses. The standardized DNA repair competence assay was used to test the efficacy of the fast DNA repair process in G0 cells. Cytogenetic preparations were made in fresh blood samples before and after challenging cells in vitro with X-ray dose. The frequency of sister chromatid exchanges (SCE) and percentage of cells with significantly elevated numbers of SCE were used as cytogenetic biomarkers associated to homologous recombination and compared to reported earlier cytogenetic biomarkers of cancer risk. Strong individual variation in the biomarkers is observed in all investigated groups before and after challenging. Nevertheless, the efficiency of post challenging fast repair is significantly high in the patients exposed to diagnostic I-131 doses than in unexposed control group and linked to decreased cytogenetic damage. However, 5 weeks after administration of therapeutic doses, significant increases of unrepaired post challenging DNA and cytogenetic damages were observed indicating a health risk. Results also suggest that the appearance of cancers in immediate families might influence DNA repair differently in patients exposed to low than to high doses.

SLFN11 inhibits checkpoint maintenance and homologous recombination repair.

High expression levels of SLFN11 correlate with the sensitivity of human cancer cells to DNA-damaging agents. However, little is known about the underlying mechanism. Here, we show that SLFN11 interacts directly with RPA1 and is recruited to sites of DNA damage in an RPA1-dependent manner. Furthermore, we establish that SLFN11 inhibits checkpoint maintenance and homologous recombination repair by promoting the destabilization of the RPA-ssDNA complex, thereby sensitizing cancer cell lines expressing high endogenous levels of SLFN11 to DNA-damaging agents. Finally, we demonstrate that the RPA1-binding ability of SLFN11 is required for its function in the DNA damage response. Our findings not only provide novel insight into the molecular mechanisms underlying the drug sensitivity of cancer cell lines expressing SLFN11 at high levels, but also suggest that SLFN11 expression can serve as a biomarker to predict responses to DNA-damaging therapeutic agents.

Identification of chromosome instability in Japanese quail (Coturnix japonica)

1. A study of the incidence of chromosome instability in the Japanese quail as assessed by sister chromatid exchange (SCE) and fragile site identification in chromosomes was conducted in two parent breeds and their F1 and F2 generations.2. The mean incidence of SCEs was 6.02 ± 0.45 and the frequency of fragile sites was 1.17 ± 0.79.3. There were moderately negative correlations of 0.51–0.64 between chromosome instability and fertility in the F1 and 0.10–0.23 in the F2. The hatch of fertilised eggs was negatively correlated with the number of SCE in male (0.31) and female (0.33) F1 and was lower in P (0.18 and 0.19, respectively), whereas the correlations were similar for the number of fragile sites in both generations (0.51–0.62).

Sister chromatid exchange analysis in cats (&amp;lt;i&amp;gt;Felis catus&amp;lt;/i&amp;gt;)

Abstract. Sister chromatid exchange (SCE) is one of the cytogenetic methods which diagnoses damage to chromosomes and allows evaluation of the mutagenic influence of a given factor on a cell’s DNA. The purpose of the experiment was to determine the level of spontaneous and inductive SCE in the domestic cat. The research was carried out on 23 domestic cats Felis catus. Chromosome preparations were prepared from lymphocytes of peripheral blood after 72 h of in vitro breeding with the addition of bromodeoxyuridine (BrdU) in five different concentrations: 0.25, 0.5, 1.0, 2.5, 5.0 μg/ml. Chromosomes were stained by means of the fluorescence plus Giemsa (FPG) technique in order to carry out microscopic analysis. It was stated that the level of spontaneous SCE in the domestic cat occurs at a concentration 0.5 μg/ml on the basis of research previously carried out. Higher concentrations of this substance have a genotoxic action and damage DNA of chromosomes and induct additional SCEs in chromosomes of this species. Moreover, it was stated that the number of SCEs is higher in males than females. Our research also proved that the number of exchanges increases along with age in cats of both sexes.

Terminalia catappa, an anticlastogenic agent against MMS induced genotoxicity in the human lymphocyte culture and in bone marrow cells of Albino mice

BackgroundTerminalia catappa has been used as a folk medicine for treating dermatitis, hepatitis as well as other diseases in India. It possesses anticancer, antioxidant as well as anticlastogenic characteristics. AimThe aim of the present investigation is to highlight the anticarcinogenic and antimutagenic potential of extracts of T. catappa. SubjectsAnticarcinogenic potential of methanolic extract of T. catappa has been tested against the carcinogenicity induced by methyl methanesulfonate in the in vitro and in vivo models. MethodsThe parameters for evaluation included chromosomal aberrations (CA), sister chromatid exchanges (SCEs) and replication indices (RI) both in the presence as well as in the absence of exogenous metabolic activation system (in vitro study) and total aberrant cells and the frequencies of aberrations were used (for in vivo methods). ResultsAlcoholic extracts of T. catappa significantly reduce chromosomal aberration from 34.42%, 70.65% and 82.80% at 24, 48, and 72h produced by methyl methanesulfonate (MMS) to 22.77%, 49.60% and 42.50% levels. Similarly the number of sister chromatid exchanges was reduced from 6.20 per cell to 3.10 per cell at 48h of treatment and replication index was enhanced in vitro for each concentration and duration of treatment. Further their ameliorating potential was dose and duration dependant. Similarly these extracts significantly reduced the number of aberrant cells or frequency of aberrations per cell in vivo. ConclusionExtracts of T. catappa significantly reduced chromosomal aberrations up to 11.65% to 40.30% at different dosages against MMS induced toxicity, similarly sister chromatid exchange was reduced and replication index enhanced in vitro. Similarly in the in vivo experiments, the effective reduction in clastogeny ranges from 19.70% to 40.90%. Their reducing potential was time and dose dependant.

Antigenotoxic capacity of beta-caryophyllene in mouse, and evaluation of its antioxidant and GST induction activities.

The present report was designed to determine the antigenotoxic capacity of beta-caryophyllene (BC) on the damage induced by benzo(a)pyrene (BaP) in mouse. We found no genotoxic potential of BC, and a significant inhibitory effect on the number of sister-chromatid exchanges (SCE) and chromosomal aberrations induced by BaP. The three tested doses of the agent (20, 200, and 2,000 mg/kg) produced a dose-dependent decrease of the two evaluated cytogenetic parameters. In comparison with the effect induced by BaP, the best inhibitory effect (about 80%) was obtained with the high tested dose of BC considering the two evaluated parameters. Other aim of the study was to explore whether in this effect participated the BC antioxidant capacity and/or its effect as inducer of GST activity. We found a dose-dependent decrease induced by BC in regard to both the oxidation of lipids and proteins produced by BaP.In the case of GST, when BC was administered alone we found a mean increase of 64% of the enzyme activity, respect to the control level, and when BC was administered in mice treated with BaP the increase obtained with the high dose of BC reached 27%. Therefore, our data established no in vivo genotoxicity by BC, and a significant antigenotoxic potential of the compound, which may be related with its capacity to block the molecular oxidation and to stimulate the GST activity.

Increased frequency of chromosomal aberrations and sister chromatid exchanges in peripheral lymphocytes of radiology technicians chronically exposed to low levels of ionizing radiations

Chromosome aberrations (CAs) and sister chromatid exchanges (SCEs) frequencies were estimated in peripheral lymphocytes from 21 radiology technicians, and from 21 non-exposed control subjects. We exclusively considered individuals who neither smoke nor consume drugs or alcohol for a period of at least two years prior to the analysis. Significant differences were found between exposed and controls in terms of SCEs and CAs frequencies.Technicians showed a significant higher number of high-frequency individuals (HFIs) with respect to the control group. Nevertheless, the mean frequency of SCEs observed among technician HFIs did not significantly differ with respect to that observed among control HFIs. Vice versa, the non-HFIs belonging to technicians group showed a statistically higher difference in the SCEs/NSM value with respect to the non-HFIs belonging to control group. Since the differences in the SCEs frequencies between the two groups are due to non-HFIs, our results seem to indicate a general genotoxic effect of the IR, not affected by HFIs.Among technicians, the level of chromosome damage correlated neither with years of radiation exposure nor with the age of the subjects. Vice versa, in the control group, a positive correlation was found between the number of SCEs and age. In both samples the gender status did not influence the frequencies of CAs and SCEs.Our results suggest that chronic long-term exposure to low doses of ionizing radiation could increase the CAs and SCEs frequencies. This study reinforces the relevance of the biomonitoring of hospital workers chronically exposed to ionizing radiation.

Chromosomal damage in peripheral blood lymphocytes from nurses occupationally exposed to chemicals

In the present study, we evaluated the induced genome damage in peripheral blood lymphocytes from a sample of nurses occupationally exposed to low doses of different chemicals. A comprehensive multi-biomarker approach using cytogenetic endpoints was employed for analyzing chromosomal aberrations (CAs) and sister chromatid exchange (SCE) assay. The study included 20 nurses and 20 control subjects matched in age, gender and smoking habits. Nurses were exposed to different chemicals, such as cytostatic drugs, anaesthetics, formaldehyde and other sterilizing gases. Significant differences were found between exposure group and control group in terms of SCEs frequency (p < 0.001) but not in terms of replication index value (p = 0.845) and CAs (p = 0.236). Regression analyses indicated that the age and the exposure years did not influence the amount of the chromosomal damage among nurses. Vice versa, among controls, a positive correlation was found between the number of SCEs and age. In conclusion, our results suggest that a continuous long-term exposure to low doses of chemicals could result in increased levels of SCEs among nurses. This data emphasize the importance of biomonitoring nurses and other hospital workers handling drugs.

Influence of genetic polymorphisms on biomarkers of exposure and effects in children living in Upper Silesia

This article is a follow-up to our previous molecular epidemiology studies on the DNA damage in children from the Upper Silesia region of Poland. It is expected that metabolic and DNA repair gene polymorphisms may modulate individual susceptibility to environmental exposure. In this study, we investigate the association between polymorphisms of metabolising (CYP2D, EPHX1, GSTM1, GSTP1, GSTT1, NAT2) and DNA repair (XPD, XRCC1, XRCC3) genes and selected biomarkers of exposure and effect such as levels of 1-hydroxypyrene (1-OHP) and urinary mutagenicity, aromatic DNA adducts, sister chromatid exchange (SCE) and micronuclei (MN) in 74 children. Both 1-OHP concentration and urinary mutagenicity tested by TA98+S9 were significantly higher in individuals with EPHX1 (exon 4) Arg/Arg genotype than in individuals with other genotype. The EPHX1 (exon 3) significantly affected urinary mutagenicity tested with strain YG1024+S9. The urinary mutagenicity in individuals with Tyr/Tyr homozygotes was lower than in individuals with Tyr/His and His/His (1057±685 vs. 1432±1003 revertants/mol creatinine). XRCC3 Met/Met genotype was associated with significantly higher levels of 1-OHP in urine compared with only The/Met genotype. The PAH-DNA adduct levels in the subgroup with GSTM1 null genotype was 2-fold higher than in individuals with GSTM1 active (7.06±5.12 vs. 13.14±9.81 adduct/10(8) nucleotides). The mean level of aromatic DNA adducts in children with deletion of the GSTT1 gene was significantly higher compared with individuals with that gene present (8.03±6.23 vs. 14.66±10.70 adduct/10(8) nucleotides). Also the carriers of the XPD Lys/Lys genotype showed higher levels of DNA adducts than heterozygotes (13.16±9.70 vs. 6.81±5.86 adducts/10(8) nucleotides). Children carrying the XRCC3-241 Met/Met genotype exhibited a higher number of SCE in peripheral blood lymphocytes than carriers of Thr/Met allele (8.15±0.86 vs. 7.62±0.79 SCE/cell). It was also observed that children with the GSTP1 slow conjugator had significantly elevated MN in peripheral blood lymphocytes compared with fast conjugator (4.23±3.49 vs. 6.56±5.00 MN/1000 cells).

Genotoxicity of pemetrexed in human peripheral blood lymphocytes

Pemetrexed (PMX) is an antineoplastic antifolate used in the treatment of non-small cell lung cancer, mesothelioma and several types of neoplasms. Its toxicity in tumor cells has been linked with the potent inhibition of thymidylate synthase, dihydrofolate reductase and glycinamide ribonucleotide formyl transferase, and subsequent depletion of both purine and pyrimidine nucleotides. However, cytogenetic toxicity of PMX in non-diseased cells has not been adequately studied; despite the increasing data on the DNA-damaging potential of antineoplastic agents on normal cells. In the present study, the genotoxic potential of PMX was evaluated in peripheral blood lymphocytes obtained from healthy human subjects using chromosome aberration (CA), sister chromatid exchange (SCE) and micronucleus (MN) assays as the cytogenetic damage markers. Human peripheral blood lymphocytes were exposed to four different concentrations (25, 50, 75 and 100μg/mL) of PMX for 24- and 48-h treatment periods. PMX significantly increased the formation of CA in 24-h treatment, but not in 48-h treatment. PMX did not increase the mean SCE frequency in 24- and 48-h treatment periods; however, there was a striking increase (although not statistically significant, p>0.05) in the number of SCEs at 25μg/mL (24- and 48-h treatment) and 50μg/mL (24-h treatment) due to an increase of SCE at the single-cell level. Interestingly, PMX did not induce MN formation in either 24- or 48-h treatment periods. PMX strongly decreased the mitotic index (MI), proliferation index (PI) and nuclear division index (NDI) in 24- and 48-h treatment periods. Our results suggest that PMX has a potent cytotoxic effect against human peripheral blood lymphocytes at concentrations which are reached in vivo in the blood plasma.