Increase In Sister Chromatid Exchange Frequency Research Articles

Analysis of Sister Chromatid Exchanges and Proliferation of Human Peripheral Blood Lymphocytes Exposed to Epoxiconazole

Abstract The potential genotoxic/cytotoxic effect of epoxiconazole was evaluated by means of sister chromatid exchanges (SCE) following the 24 and 48 h in vitro exposure of human peripheral blood lymphocytes to epoxiconazole at concentrations of: 5, 10, 25, 50 and 100 μg. ml–1. Dimethyl sulphoxide (DMSO), used as an epoxiconazole solvent, was used as a negative control and mitomycine (MMC) as a positive control. After the 24-hour exposure, we failed to observe a significant increase in SCE frequencies in comparison with the negative control, however, the concentrations of 10—100 μg.ml–1 caused a significant decrease in the proliferation index (PI; P < 0.001). Also, the 48-hour exposure produced no significant alterations in the SCE frequencies in comparison with the control. At epoxiconazole concentrations ranging from 10 to 50 μg.ml–1 we recorded a moderate to strong, dose-dependent inhibition of PI (P < 0.05; P < 0.01; P < 0.001), while at the highest dose (100 μg.ml–1) the reduction in PI compared to the control was less pronounced (P < 0.05). The reduction in PI at the concentration range of 10—100 μg.ml–1 depended on the number of cells in the M1, M2 and M3 phases of the cell cycle per total number of 100 evaluated metaphases. Our results indicated a significant cytotoxic or cytostatic effect on human peripheral blood lymphocytes.

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.

The genotoxic effects of anti-cancer drug gossypol on human lymphocytes and its mitigation by melatonin

Purpose of study: To determine melatonin as a potential natural antioxidant to mitigate the genotoxic effects of promising anti-cancer drug gossypol in human lymphocytes. Introduction: Gossypol, is a polyphenolic compound naturally occurring in cotton seed, was originally identified as a male contraceptive but it has several proposed clinical applications. Gossypol has anti-proliferative effects on cancer cell lines. However, its genotoxic effects on normal cells are not much studied. Hence, there is a paucity of data available. Hence, the study was conducted to investigate gossypol-induced genotoxic effects on lymphocytes. Methods: Peripheral blood lymphocyte cultures (PBLC) were done and exposed by two different doses of an anti-cancer drug, gossypol (0.274 mM, 1.645 mM) to check genotoxic effects. Melatonin (0.2 mM) is used as an antioxidant. Genotoxic indices such as sister chromatid exchanges (SCEs), cell cycle proliferative index (CCPI), average generation time (AGT), population doubling time (PDT) were assayed in the cultures. Result: Gossypol-treated groups indicated significant increases in frequency of SCEs calculated for SCE/plate and SCE/chromosome. Furthermore, CCPI showed a remarkable reduction and increased AGT and PDT levels were found in exposed cultures. When the higher dose of gossypol cultures was treated along with melatonin, these indices were found to be declined and comparable to control. Conclusion: Gossypol, an anti-cancer drug, induces genotoxicity on lymphocyte cells and co-supplementation of melatonin antioxidant ameliorates these toxic effects of gossypol.

Sister chromatid exchange: A possible approach to characterize familial breast cancer patients.

Sister chromatid exchange (SCE) frequency is widely used as an indicator of spontaneous chromosome instability. We investigated SCE frequency in the peripheral blood lymphocytes of familial and sporadic breast cancer (BC) patients from the Apulian Caucasian Population. Eighty-one patients were enrolled: 22 with familial history and 59 sporadic patients. Eleven familial patients had an 'increased risk' of BRCA gene mutation (BRCAPro ≥ 10%) and were candidates for BRCA1 and BRCA2 mutation analysis. For these reasons, we stratified the 22 familial BC patients in two group: 'low-risk' (n=11) and 'high-risk' (n=11) patients for BRCA gene mutations. Two of these 11 'high-risk' patients (18%) had pathogenic mutations in the BRCA2 gene. The subjects were not cigarette smokers or alcohol or drug users, and had no genetic disorders or chronic diseases affecting the family. Our results showed a significant increase in SCE frequency in the familial (5.305 ± 1.088/metaphase) (P<0.0001) and the sporadic patients (3.943 ± 0.552) (P<0.0001) compared to the controls (3.197 ± 0.649). We found that the SCE frequency was always significantly higher in familial than in sporadic patients, regardless of their clinicopathological characteristics. Moreover, we observed that the frequency of SCE in BRCA2 mutation carrier patients was higher compared to patients without mutations in BRCA1/2 genes. These findings highlight an intrinsic genomic instability in familial patients, and we suggest that SCE frequency may be used as a biomarker to better characterize familial BC.

A novel frameshift mutation in BLM gene associated with high sister chromatid exchanges (SCE) in heterozygous family members.

The Bloom syndrome (BS) is an autosomic recessive disorder comprising a wide range of abnormalities, including stunted growth, immunodeficiency, sun sensitivity and increased frequency of various types of cancer. Bloom syndrome cells display a high level of genetic instability, including a 10-fold increase in the sister chromatid exchanges (SCE) level. Bloom syndrome arises through mutations in both alleles of the BLM gene, which was identified as a member of the RecQ helicase family. In this study, we screened a Tunisian family with three BS patients. Cytogenetic analysis showed several chromosomal aberrations, and an approximately 14-fold elevated SCE frequency in BS cells. A significant increase in SCE frequency was observed in some family members but not reaching the BS patients values, leading to suggest that this could be due to the heterozygous profile. Microsatellite genotyping using four fluorescent dye-labeled microsatellite markers revealed evidence of linkage to BLM locus and the healthy members, sharing higher SCE frequency, showed heterozygous haplotypes as expected. Additionally, the direct BLM gene sequencing identified a novel homozygous frameshift mutation c.3617-3619delAA (p.K1207fsX9) in BS patients and a heterozygous BLM mutation in the family members with higher SCE frequency. Our findings suggest that this latter mutation likely leads to a reduced BLM activity explaining the homologous recombination repair defect and, therefore, the increase in SCE. Based on the present data, the screening of this mutation could contribute to the rapid diagnosis of BS. The genetic confirmation of the mutation in BLM gene provides crucial information for genetic counseling and prenatal diagnosis.

Potentiation by caffeine of cytogenetic damage induced by steroidal derivatives in human lymphocytes in vitro

We studied the effects of three newly synthesized steroidal derivatives of nitrogen mustards, alone or in combination with caffeine, on sister chromatid exchange (SCE) frequencies and on human lymphocyte proliferation kinetics. The agents have as alkylator functionalities either P-N,N-bis(2-chloroethyl)aminophenyl-buturate (CHL) or P-N,N-bis(2-chloroethyl)aminophenyl-acetate (PHE), esterified with a modified steroidal nucleus. An enhancement of SCE frequency was seen with compounds which contain either PHE or CHL as alkylators and are esterified with a steroidal nucleus having added a cholestene group in the 17-position of the D-ring. The exocyclic insertion of an –NHCO– group in the D-ring of the steroidal nucleus esterified with PHE (amide ester of PHE) gave a compound showing increased SCE frequency. Enhanced cytogenetic damage was observed when lymphocytes were exposed in vitro to caffeine. The compounds, alone or in combination with caffeine, caused a concentration-dependent increase in SCE frequencies and cell division delays, and caffeine was found to act synergistically with the steroidal alkylators.

Detection of genotoxicity and mutagenicity of chlorthiophos using micronucleus, chromosome aberration, sister chromatid exchange, and Ames tests

Potential mutagenic and genotoxic effects of Chlorthiophos, an organophosphate pesticide, were evaluated using four standard assays. Five different concentrations of the pesticide were tested by an Ames test using Salmonella typhimurium strains TA97, TA98, TA100, and TA102, with and without S9 metabolic activation. No concentrations of Chlorthiophos showed mutagenic activity on the TA97, TA100, and TA102 strains, with and without S9 fraction, but were all mutagenic to the TA98 strain without S9. Sister chromatid exchange (SCE), chromosome aberration (CA), and micronucleus (MN) tests were used to investigate the genotoxic effects of Chlorthiophos in human peripheral lymphocytes treated with 25, 50, 100, and 200 µg/mL concentrations of Chlorthiophos for 24 and 48 h. The nuclear division index (NDI), replication index (RI), and mitotic index (MI) were also calculated to determine the cytotoxicity of Chlorthiophos. No increase in SCE frequency was seen for any treatment period or concentration, but Chlorthiophos at 200 µg/mL increased the frequency of CAs. Increases in MN formation were only observed at Chlorthiophos concentrations of 200 µg/mL following 24 and 48 h treatments. Chlorthiophos treatment reduced the MI and NDI significantly, but had no effect on the RI.

The genotoxic and antigenotoxic effects of Salvia fruticosa leaf extract in human blood lymphocytes

The aim of this study was to investigate the genotoxic and antigenotoxic effects of Salvia fruticosa (Sf) leaf extract with the absence and presence of S9 mix using sister chromatid exchange (SCE), chromosome aberration (CA) and micronucleus (MN) formation test systems in human peripheral blood lymphocytes (HPBLs) that were treated with 1.5-, 3.0- and 6.0-µL/mL concentrations for 24- and 48-hour treatment periods. The cytotoxicity of Sf leaf extract was also investigated by calculating the mitotic index (MI), proliferation index (PI) and nuclear division index (NDI). In the absence of S9 mix, Sf leaf extract alone increased SCE frequency at the 48-hour treatment period; however, it induced the CA and MN at all concentrations and at all treatment periods. Sf plus MMC (mitomycin C) synergically induced SCE and CA, except the highest concentration of Sf leaf extract and MMC on induction of SCE. In addition, Sf leaf extract induced the effect of MMC on MN frequency for 24 hours, but it significantly decreased the effect of MMC on MN frequency for the 48-hour treatment period. Sf leaf extract showed a cytotoxic effect by decreasing the MI; however, it did not decrease the PI and NDI. In the presence of S9 mix, Sf leaf extract did not increase the SCE, when compared to solvent control, whereas it reduced the effect of cyclophosphamide (Cyp). Sf leaf extract induced the CA and MN, but could not increase the effect of Cyp on CA and MN formation. Sf leaf extract had no cytotoxic effect; however, it induced the cytotoxicity of Cyp.

Recent microwave research studies of Gazi Biophysics &amp; Gazi Non-Ionizing Radiation Protection Center

Recent microwave research studies of Gazi Biophysics &amp; Gazi Non-Ionizing Radiation Protection Center

Relationship between carbon monoxide intoxication and sister chromatid exchange in lymphocytes

Carbon monoxide (CO) intoxication can be serious and is reported to be the cause of more than half of all fatal intoxications. In this study, we aimed to identify its genotoxic effects based on sister chromatid exchange (SCE). CO-poisoned patients presented to the emergency services department were identified. Their demographic characteristics, vital findings, laboratory markers, source of CO gas, risk factors, and smoking habits were recorded. The genotoxic effect was assessed using the SCE method. A total of 38 patients were recruited. Their ages ranged from 16-64years (mean: 29.79±10.92years). In all the cases, the source of CO gas was a flash heater. The mean carboxyhemoglobin (COHb) level was 25.05±7.15%. Of all the patients, 12 (31.6%) had a the Glasgow Coma Scale (GCS) scores of less than 15, and an important negative correlation was found between the GCS and COHb level (r=-0.825; p<0.001). Genotoxicity investigations revealed a significantly higher SCE frequency among patients with high COHb levels compared with that of control subjects with physiological COHb levels (p<0.001). However, no correlation between increased SCE frequency and COHb level was found (r=0.16; p=0.34). CO poisoning was shown to result in genotoxicity via an increase in the frequency of SCE. This study is the first to demonstrate a genotoxic effect of CO independent of other chemicals.

Cytogenetic Effects of Valproic Acid and Ziprasidone in Human Lymphocyte Cultures

Background/Aims: Valproic acid or valproate (VA) is an anticonvulsant and mood-stabilizing drug primarily used in the treatment of epilepsy and bipolar disorder. Ziprasidone (ZPN) is an atypical antipsychotic drug used mainly for the treatment of schizophrenia. Methods: This study is a part of our investigation on the cytogenetic effects of psychotropic drugs. Lymphocytes of peripheral blood cultures from 3 healthy donors treated with VA, ZPN and combinations of these (at concentrations equivalent to the oral doses) were used for the estimation of sister chromatid exchanges (SCEs) and the proliferation rate index (PRI). As a biomarker of genotoxicity, we used SCEs, one of the most sensitive methods reflecting DNA damage and/or subsequent DNA repair, and as a marker of cytostaticity we estimated the PRI. Results: All treated lymphocyte cultures showed a statistically significant increase in SCE frequency and a significant decrease in PRI values (p < 0.001). The combined effect of the drugs induced similar or more intense results, without reaching levels indicating synergistic action. Conclusion: This in vitro study investigated the cytogenetic activity of monotherapy vs. combined chronic drug exposure, and could form a catalyst for further investigations aiming to develop more efficacious therapy with decreased cytogenetic damage.

Evaluation of genotoxic and oxidative effects in workers exposed to jet propulsion fuel

Jet fuel is a common occupational exposure risk among military and civilian populations. The purpose of this study was to evaluate genotoxic and oxidative effects in workers occupational exposure to jet propulsion fuel (JP-8). In this study, sister-chromatid exchange (SCE), high frequency of SCE cells (HFCs), and micronuclei (MN) were determined for 43 workers exposed to JP-8 and 38 control subjects. We measured the antioxidant enzyme activities including that of superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT). The levels of thiobarbituric acid-reactive substances (TBARS) were also studied. Urinary 1- and 2-naphthol excretion was used as a biomarker of occupational exposure to JP-8. The results obtained from cytogenetic analysis show a statistically significant increase in frequency of SCE in the exposed workers when compared to controls (P<0.05). Interestingly, the mean value of the frequency (%o) of MN and HFCs for workers and controls did not show any statistical differences (P>0.05). Oxidative stress parameters were not statistically different between exposed and control groups except for TBARS levels. Urinary 1-and 2-naphthol levels of exposed workers were found to be significantly higher than those of control subjects. Occupational exposure to JP-8 resulted in no significant genotoxic and oxidative effects, while smoking is the principal confounding factor for the some parameters. To understand the genotoxic and oxidative effects of JP-8 exposure, further studies should be planned to find out whether human populations may be at increased risk for cancer because of the exposures related to occupation and lifestyle.

Telomere alterations and genomic instability in long-term cultures of normal human fibroblasts irradiated with X rays and protons

Telomeres are the end of linear chromosomes, responsible for chromosome stability and cell viability. It is well known that radiations are able to induce chromosome instability but it has not yet been investigated whether telomere structure is affected by the radiation exposure and if radiations with different quality act in a different way on telomeres. The effect of radiations with different quality on telomere structure and chromosome instability was analysed in human primary fibroblasts exposed to X rays or low-energy protons (28.5 keV μm(-1)). Telomere length was evaluated at different harvesting times from 24 h up to 360 h (15 days), whereas chromosome instability was evaluated in terms of sister chromatid exchanges (SCEs) (48 h from irradiation) and chromosome painting (360 h from irradiation). Results indicated a delayed telomere lengthening 360 h after X-ray treatment, whereas protons were able to induce such a lengthening shortly from irradiation as well as at longer harvesting times. Data obtained from chromosome instability analysis indicated an increase of SCE frequency only after proton irradiation, but, on the contrary, at the longer harvesting time chromosome painting analysis displayed a higher frequency of aberrations after X-ray treatment, suggesting a role of selective process against highly damaged cells.

Chromosome Instability in Patients with Chronic Renal Failure

The aim of this study was to investigate the frequency of sister chromatid exchanges (SCEs), the presence of cytostaticity, cytotoxicity, and therefore, the possible genetic instability in patients with chronic renal failure (CRF) in human cultured peripheral blood lymphocytes. Peripheral blood lymphocytes were cultured from 32 patients with CRF (average 55.2 years) and 18 healthy blood donors (average 44.6 years), and the SCE method was applied afterward. The increase in SCE frequency was evaluated as an immediate DNA damage index, while the reduction in the values of the proliferating rate indices was evaluated as a cytostatic index and the mitotic indices as a cytotoxic index was also measured. A significant increase in the SCE frequencies along with a significant reduction in mitotic indices was observed in patients with CRF compared with the controls. It is notable that there was no significant difference in SCE levels among patients with CRF and cancer, and patients with CRF alone. This study illustrates increased genetic instability in patients with CRF. These results could also be of a great importance in early diagnosis to prognosticate a possible generation of neoplasm in the future.

Differences in chemical structure result in opposite cytogenetic behavior of benzodiazepines

Event Abstract Back to Event Differences in chemical structure result in opposite cytogenetic behavior of benzodiazepines Maria T. Ekonomopoulou1*, Maria Argyraki1, Doxakis Anestakis1 and Zafiroula Iakovidou-Kritsi1 1 Aristotle University of Thessaloniki, Laboratory of General Biology and Genetics, Greece Introduction. Benzodiazepines (BDZs) belong to the most commonly prescribed drugs for the treatment of a variety of psychological and physical diseases. Especially some of 1,4-BDZs possess a leading role as anxiolytic, sedative, hypnotic, anticonvulsant and muscle relaxant drugs. 1,4-BDZs have an aromatic benzene ring fused to 1,4-diazepine ring with various substituents. Despite their extended use in therapy, they present widely varying pharmacokinetic behavior and the majority of them do not have retrievable genotoxicity or carcinogenicity data. 1,5-BDZs is a group of polycyclic compounds with characteristic seven-membered heterocyclic rings. Though some members of them have important biological properties, there is lack of information on their effect on DNA. Materials and methods. We studied the cytogenetic effects of four of the most widely used 1,4-BDZs, alprazolam (AZ), bromazepam (BZ), diazepam (DZ) and lorazepam (LZ) in normal human lymphocyte cultures, using an expanded sample set, administering them at final concentrations equivalent to oral dosage. Then, we synthesized four 1,5-BDZs with small structural differences and investigated their cytogenetic activity in normal human lymphocyte cultures at concentrations equivalent to the per os doses of the 1,4-BDZs. Sister chromatid exchanges (SCEs) have been used as one of the most sensitive index of cytotoxic activity reflecting instability of DNA or/and a deficiency in DNA repair mechanisms. Proliferation rate index (PRI) has been estimated as a valuable marker of cytostaticity. Results. All four 1,4-BDZs caused a concentration-dependent, statistically significant increase of SCE frequency (p<0.001) followed by a statistically significant decrease of PRI (p<0.001) of lymphocytes. Three of the newly synthesized 1,5-BDZs exhibited positive cytogenetic activity (statistically significant reduction of SCEs, p<0,01 t-test), without showing cytostatic properties. Conclusion. The observed unexpected decrease of SCE frequency of the cultured lymphocytes due to 1,5-BDZs’ activity, in contrast to the genotoxic and cytostatic behavior of the 1,4-BDZs, is remarkable and requires further investigation in the effort to improve pharmacological effects. Keywords: cytogenetic effects, DNA, Benzodiazepines Conference: 8th Southeast European Congress on Xenobiotic Metabolism and Toxicity - XEMET 2010, Thessaloniki, Greece, 1 Oct - 5 Oct, 2010. Presentation Type: Oral Topic: Xenobiotic toxicity Citation: Ekonomopoulou MT, Argyraki M, Anestakis D and Iakovidou-Kritsi Z (2010). Differences in chemical structure result in opposite cytogenetic behavior of benzodiazepines. Front. Pharmacol. Conference Abstract: 8th Southeast European Congress on Xenobiotic Metabolism and Toxicity - XEMET 2010. doi: 10.3389/conf.fphar.2010.60.00118 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 28 Oct 2010; Published Online: 04 Nov 2010. * Correspondence: Dr. Maria T Ekonomopoulou, Aristotle University of Thessaloniki, Laboratory of General Biology and Genetics, Thessaloniki, Greece, biomary@med.auth.gr Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Maria T Ekonomopoulou Maria Argyraki Doxakis Anestakis Zafiroula Iakovidou-Kritsi Google Maria T Ekonomopoulou Maria Argyraki Doxakis Anestakis Zafiroula Iakovidou-Kritsi Google Scholar Maria T Ekonomopoulou Maria Argyraki Doxakis Anestakis Zafiroula Iakovidou-Kritsi PubMed Maria T Ekonomopoulou Maria Argyraki Doxakis Anestakis Zafiroula Iakovidou-Kritsi Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Evaluation of chromosome aberrations, sister chromatid exchange and micronuclei in patients with type-1 diabetes mellitus

Oxidative stress-induced DNA damage seems to play a role in the pathogenesis of type-1 diabetes mellitus and its complications. Several in vitro assays have been used to measure the DNA damage produced by oxidative stress. In the present study, we aimed to investigate the frequency of sister chromatid exchange (SCE), chromosomal aberrations (CA) and micronuclei (MN) in type-1 diabetes mellitus patients compared with healthy controls. SCE, CA and MN tests were carried out with the blood-cell cultures from 35 type-1 diabetic patients and 15 healthy, age- and sex-matched control subjects. The mean age of the type-1 diabetic patients was 31.89 ± 10.01 years, with a mean duration of the diabetes of 7.8 ± 6.02 years. The mean level of HbA1c of the type-1 diabetic patients was 8.37 ± 1.36%. Only three (8.5%) patients with type-1 diabetes mellitus had an HbA1c level below 7%. Patients with type-1 diabetes mellitus showed a higher frequency of SCE compared with controls (5.44 ± 1.47 and 2.54 ± 0.82, respectively, p < 0.001), but there was no significant correlation between the duration of diabetes, HbA1c and SCE. No significant difference was found in CA or MN frequency in type-1 diabetic patients compared with controls. In conclusion, these results suggest that type-1 diabetes mellitus is a condition with genomic instability characterized by an increased level of SCE. Hyperglycemia-induced oxidative stress may be the underlying factor of the increased SCE frequency.

Cytogenetic Activity of Diazepam in Normal Human Lymphocyte Cultures

Diazepam (DZ) belongs to benzodiazepines, a group of drugs used for sedation, for the relief of anxiety, and in the treatment of epilepsy. It has been found that DZ influences cytotoxic activity and diminishes antiviral and antitumor reactions in human natural killer cells in vitro. It has also been demonstrated that DZ causes a significant increase in the frequency of chromosomal aberrations in human lymphocytes in vitro. In the present research the cytogenetic effects of DZ have been studied in normal human lymphocyte cultures of peripheral blood at 17.6-211.2 microM (final concentrations). Sister chromatid exchanges (SCEs), one of the most sensitive methods reflecting instability in DNA or a deficiency in DNA repair mechanisms, and proliferation rate index (PRI), a valuable indicator for cytostatic activity, have been evaluated. After 72-h incubation, DZ was found to cause a dose-dependent, statistically significant increase of SCE frequency (p < 0.001), followed by an equally significant decrease of PRI (p < 0.001). Our results suggest that DZ's administration presents cytogenetic effects in normal human lymphocyte cultures.

Genotoxic and cytotoxic effects of carbofuran and furadan ® on Chinese hamster ovary (CHO K1) cells

The in vitro geno- and cytotoxicity exerted by the N-methylcarbamate pesticide carbofuran (CF) and its commercial formulation furadan ® (F ®) were studied in Chinese hamster ovary (CHO K1) cells by several bioassays for both genotoxicity (e.g., the sister chromatid exchange (SCE) and micronuclei (MNi) frequencies), and cytotoxicity (e.g., cell-cycle progression, mitotic index (MI), 3(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and neutral red (NR)). Both CF and F ® activities were tested within the range of 5–100 μg/ml. CF within a 10–100 μg/ml concentration-range induced a significant dependent increase of SCE frequency and MNi over control values. At the same concentration-range, F ® increased significantly the SCE frequencies over control values although in a non-dependent manner while only an enhanced frequency of MNi was found in those 50 μg/ml-treated cultures. No binucleated cytokinesis-block cells were found in 100 μg/ml F ®-treated cultures. The NDI index revealed a delay in the onset of cell-division with 50 and 100 μg/ml of CF and F ®, respectively. The delayed rate of nuclear division induced by 100 μg/ml of F ® was higher than that induced by an equal concentration of CF. CF and F ® induced both a significant concentration-dependent delay in cell-cycle progression and a decrease in the proliferative replication index within 5–100 μg/ml and 50–100 μg/ml concentration-range, respectively. Decreased cell viability was found in up to 26% and 47% in 100 μg/ml CF- and F ®-treated cultures, respectively. The NR and MTT assays revealed a clear cell growth inhibition when concentrations of 50 and 100 μg/ml of either CF or F ® were employed. Accordingly, the results highlight that CF by itself and F ®, even in a greater extend exerts both genotoxicity and cytotoxicity in mammalian cells in culture, at least in CHO K1 cells.

Increased sister chromatid exchange frequency in lymphocytes in healthy cigarette smokers.

SCE rates in peripheral lymphocytes may be useful for evaluation of environmental mutagens. Since lung cancer is strongly associated with cigarette smoking, an association of SCE with cigarette smoking might be of interest. Controversy about this question prompted the present study of SCE in peripheral lymphocytes in 149 healthy, unmedicated persons. 60 non-smokers had 8.25 ± 0.13 SCE/cell (mean value ± standard error of the mean), and 89 cigarette smokers had 9.23 ± 0.14 SCE/cell. The sum of SCE in 30 metaphases in each person was transformed to a normally distributed metameter, y= (SCE)½+ (SCE+1)½, which was found to be significantly increased with increasing cigarette consumption. The linear regression calculated for y= (SCE)½+(SCE+1)½ and x=number of cigarettes smoked per day was y=31.43+0.094 x. It was concluded that cigarette smokers have increased SCE in peripheral lymphocytes. The significance of this in respect to risk of development of cancer in the lung is unknown. The influence of cigarette smoking should be considered when using the SCE test principle to evaluate in vivo exposure to potential mutagens.

Herbicide 2,4‐dichlorophenoxyacetic acid (2,4‐D)‐induced cytogenetic damage in human lymphocytes in vitro in presence of erythrocytes

The genotoxic effects of 2,4-D and its commercial derivative 2,4-D DMA were studied by measuring sister chromatid exchange (SCE), cell-cycle progression and mitotic index in human whole blood (WBC) and plasma leukocyte cultures (PLC). Concentrations of 10, 25, 50 and 100 microg herbicide/ml were used during 72 h. In WBC, a significant increase in SCE frequency was observed within the 10-50 microg 2,4-D/ml and 25-100 microg 2,4-D DMA/ml dose range. Contrarily, in PLC, none of the concentrations employed affected the SCEs frequency. A significant delay in cell proliferation was observed in WBC after treatments with 25 and 50 microg 2,4-D/ml and 50 and 100 microg 2,4-D DMA/ml. In PLC, only 100.0 microg 2,4-D/ml altered cell-cycle progression. For both chemicals, a progressive dose-related inhibition of mitotic activity was observed. The results demonstrated that the presence of erythrocytes in the culture system modulated the DNA and cellular damage inflicted by 2,4-D and 2,4-D DMA into human lymphocytes in vitro as well as both 2,4-D and 2,4-D DMA were more potent genotoxic agents in the presence of human red cells.