Clastogenic effect of pesticides in peripheral lymphocytes of cotton-field workers.

We studied clastogenic effects in peripheral lymphocytes of cotton-field workers who were exposed to different pesticides. All the cells were grown in RPMI 1640 medium for 48 and 72 h. The type of aberrations observed in the exposed group are gaps, breaks, dicentrics, exchanges, rings and polyploidy. The frequency of total chromosomal aberrations increased significantly in male pesticide applicators when compared to controls. A significant decrease in mitotic index was observed in the exposed group as compared to the control group. The 48-h cultures showed high incidence of chromosomal aberrations and low mitotic index when compared to 72-h cultures. The difference in chromosomal aberrations between 48- and 72-h cultures was not significant. 24 out of 26 individuals showed ill health effects such as severe giddiness and nervous disorders.     

Cytogenetic effect of the anticancer drug epirubicin on Chinese hamster cell line in vitro

The present study demonstrated the cytogenetic effect of the anticancer drug epirubicin on cultures of Chinese hamster cell line in vitro. The cultures were exposed to the drug for 24 h at three final concentrations; 10, 20 and 40 microg/ml. All treatments were carried out in the absence of any exogenous metabolic activation system.The different types of structural chromosomal aberrations, including gaps, breaks, deletions and fragments were increased in epirubicin-treated cultures. This increase was dose dependent where there was a positive correlation between increased drug concentration and induction of structural chromosomal aberrations. Also, the numerical chromosomal aberrations, including hypodiploidy and hyperdiploidy, were increased significantly in epirubicin-treated cultures. Like structural aberrations, the increase of numerical chromosomal aberrations was also dose-dependent.The frequency of sister chromatid exchanges in cultures treated with epirubicin increased significantly and this increase was dose-dependent. On the other hand, the epirubicin significantly decreased the mitotic index in treated cultures of Chinese hamster cell line.     

Proliferative kinetics and mitomycin C-induced chromosome damage in Fanconi's anemia lymphocytes

Lymphocytes from two sisters with Fanconi's anemia (FA) were studied for cell cycle kinetics, sister chromatid exchanges (SCEs), and chromosomal aberrations when they had undergone one, two, or three or more divisions in mitomycin C (MMC)-treated cultures. Lymphocytes from the parents, another sister of the probands, and a healthy unrelated adult were examined as controls. Analyses of cell cycle kinetics by the sister chromatid differential staining method revealed that the relative frequency of metaphase cells at their third or subsequent divisions was much smaller in untreated FA cultures than in normal cultures fixed at 96 h after phytohemagglutinin stimulation. These data indicate that FA cells proliferate much more slowly than normal cells. MMC treatments of FA and normal cells led to a clearly dose-related delay in cell turnover times, the duration of delay being much longer in FA than in normal cells. FA cells had about 1.4 times higher frequencies of SCEs than normal cells in both MMC-treated and untreated cultures. FA cells also showed several times higher frequencies of chromosomal aberrations than normal cells, and the frequency of chromosomal aberrations decreased through subsequent mitoses by approximately 60% in both FA and normal cells.     

Cytogenetic effects in workers occupationally exposed to tobacco dust

Tobacco dust mainly contains nitrosamines, which are readily absorbed by the body tissues like skin, respiratory epithelium, and mucous membrane of mouth, nose and intestines. Exposure to tobacco dust is known to affect the respiratory tracts in humans. In the present study, cytogenetic effects of exposure to tobacco dust are evaluated in 154 male tobacco factory workers and 138 age and sex matched controls by analysing chromosomal aberrations in their peripheral blood lymphocytes. The workers were in the age group of 20-55 years and were employed in the tobacco processing factory for 1-32 years. Heparinised blood samples were collected from workers and control subjects and lymphocyte cultures were carried out by using standard technique. Slides were prepared and 150 metaphases were screened for each sample for various structural and numerical types of abnormalities. A statistically significant increase was observed in the frequencies of chromosomal aberrations in non-smoking and smoking exposed groups when compared to the respective controls. An increase in the frequencies of chromosomal aberrations was also observed with increase in years of service in the exposed subjects.     

Cytotoxic effects of Sumicidin, a type II synthetic pyrethroid, on mice in vivo at 6, 12 and 24 h after exposure.

The ability of Sumicidin, a synthetic pyrethroid, to induce cytotoxicity in Swiss albino mice was evaluated before completion of the first cell division following oral exposure. Mice were administered orally different concentrations (32.50, 75 and 150 mg/kg body wt) of Sumicidin in a single dose. Mitotic index and chromosomal aberrations were screened after 6, 12 and 24 h following exposure. The frequency of dividing cells decreased significantly, indicating mitostatic action. The frequency of chromosomal aberrations was directly related to the concentrations used and the duration after exposure, and was significant at all concentrations. The highest frequency of aberrations was observed 24 h after exposure.     

Chromosomal aberrations and sister-chromatid exchanges in tool and die workers

Because tool and die workers are exposed to a number of potentially genotoxic agents, including mutagenic metals, polyaromatic hydrocarbons, and nitrosamines, and may be at increased cancer risk, the present study was undertaken to test whether chromosomal damage in peripheral blood cells is associated with work in the tool and die industry. Lymphocyte cultures were established from 27 tool and die fabrication workers from one manufacturing plant who had worked in the trade for more than 15 years. 15 of these workers also had some form of malignancy at the time of the study, but had not been treated with radiation or chemotherapies that could themselves induce chromosomal damage. The frequencies of chromosomal aberrations and sister-chromatid exchanges (SCEs) were measured in workers and the data compared with those of a control group consisting of 7 non-fabrication workers from the same plant and 8 age-matched community controls. In addition, the relative rates of lymphocyte proliferation were estimated for each group by analyzing the percentages of first-, second- and third-division mitotic cells after 72 h of culture. The results of the chromosomal studies show that tool and die workers have significantly increased frequencies of aberrations whether engaged in fabrication work or not, compared to control subjects. The frequency of SCEs and the frequencies of 1st, 2nd and 3rd division figures are not different among the study groups. Among workers who are engaged in fabrication, including those who are cancer patients, the frequency of more complex aberrations (i.e., interstitial deletions and small acentric fragments) is increased. In a five-year follow-up of these workers, 2 of the 13 workers with these aberrations developed some form of colon cancer. Whether the presence of interstitial deletions and small acentric fragments is related to the occupation of these workers, or is tangentially related to the development of cancer, is presently under consideration.     

Genetic damage induced by an occupational complex and prolonged chemical exposure

Some results of a study on the clastogenicity of chemicals in vivo are reported. The chromosomes in lymphocytes from whole blood cultures were studied in 60 subjects permanently exposed for about 6 years to several occupational chemicals acting concomitantly, and in 5 controls. The exposed subjects showed an increase in the rate of chromosomal aberrations as compared to controls.     

Cytogenetic effects induced by cytochalasin B in Chinese hamster ovary cells

We determined the kinetics of the induction of chromosomal aberrations and micronuclei (MN) by mitomycin C (MMC, 0.1 µg/ml) in Chinese hamster ovary (CHO) cells treated with cytochalasin B (Cyt-B, 3 µg/ml). In cells treated with Cyt-B as well as with Cyt-B plus MMC the highest yield of binucleated cells was obtained 24 h after treatment. After 40 h of treatment with Cyt-B the frequency of MN in binucleated cells was significantly higher than that observed at previous times in the same cultures as well as in controls. In cultures treated with MMC the frequency of MN increased with time, reaching the highest value at 24 h. The frequency of chromosomal aberrations was also significantly higher in cells treated both with Cyt-B and Cyt-B plus MMC than in controls and exceeded that of MN in parallel cultures. These data confirm the capacity of MMC to induce chromosomal alterations in mammalian cells; in particular they indicate that Cyt-B is able to induce cytogenetic effects in CHO cells. Using immunofluorescence microscopy, after reaction with CREST antikinetochore antibodies, we found that in cells treated with Cyt-B or Cyt-B plus MMC the frequency of MN without kinetochore was, respectively, about 70 and 85%, indicating that under our experimental conditions MN originate mainly from acentric chromatid fragments. Present data suggest that the method based on the blockage of cytokinesis by Cyt-B normally used in the MN assay should be reconsidered.     

氯苯胁迫对蚕豆幼苗生长和细胞分裂的影响

研究了1,2,4-三氯苯(TCB)对蚕豆幼苗生长、根尖细胞分裂及染色体畸变的影响．结果表明,随TCB浓度增加和处理时间延长,蚕豆幼苗根长的生长及根尖细胞有丝分裂指数降低甚至停止．TCB诱发蚕豆根尖细胞有丝分裂过程中染色体数目畸变和结构畸变．50-100μg.g^-1TCB胁迫12-24h,蚕豆根尖染色体的主要损伤形式为c-有丝分裂、染色体桥和不均匀排列,其出现百分率达1．0％--10.3％．300μg.g^-1TCB胁迫12-96h,蚕豆根尖细胞中染色体粘连(S)、S+染色体断裂(S+B)、S+染色体环(S+R)、S+染色体不均匀排列(S+A)及S+染色体桥(S+Be)出现的百分率达47．9％--88.9％,各种类型染色体断裂出现的百分率仅为18．1％--29．6％,说明蚕豆根尖细胞染色体畸变分析可作为TCB土壤污染监测的敏感生物监测指标．     

Induction and persistence of micronuclei, sister-chromatid exchanges and chromosomal aberrations in splenocytes and bone-marrow cells of rats exposed to ethylene oxide

Studies on the induction and persistence of ethylene oxide (EO) induced chromosomal alterations in rat bone-marrow cells and splenocytes following in vivo exposure were carried out. Rats were exposed to ethylene oxide either chronically by inhalation (50-200ppm, 4 weeks, 5 days/week, 6h/day) or acutely by intraperitoneal injection (i.p.) at dose levels of 50-100ppm.Spontaneous- and induced-frequencies of micronuclei (MN), sister-chromatid exchanges (SCEs) and chromosomal aberrations were determined in rat bone-marrow cells, and in splenocytes following in vitro mitogen stimulation. Unstable chromosomal aberrations were studied in whole genome using standard Giemsa staining technique and fluorescence in situ hybridisation using probe for chromosome #2 was employed to detect chromosome translocations.Following chronic exposure, the cytogenetic analyses were carried out at days 5 and 21 in rat splenocytes, to study the induction and persistence of sister-chromatid exchanges. Following chronic exposure, ethylene oxide was effective in inducing SCEs, and markedly cells with high frequency SCEs were observed and they in-part persisted until day 21 post-exposure. However, no significant effect was observed in rat splenocytes for induction of MN and chromosomal aberrations. Following acute exposure, both SCEs and MN were increased significantly in rat bone-marrow cells as well as splenocytes.In conclusion, this study indicates that ethylene oxide at the concentrations employed by intraperitoneal injection or inhalation in adult rats is mutagenic and can induce both SCEs and MN.     

Chromosomal aberrations and sister-chromatid exchanges in workers exposed to styrene

Few studies exist about chromosomal damage in workers occupationally exposed to styrene. In the present study, chromosomal aberrations and SCEs were analyzed from cultures of peripheral lymphocytes of workers employed in 6 different reinforced-plastics industries with styrene air exposure levels ranging from 30 to 400 mg/mc. A control group was selected on the base of sex, age and smoking habit. We examined 50-h cultures (for chromosomal-aberrations) and 72-h cultures (for SCEs) for each individual. All workers exposed to styrene, as compared with controls, showed significantly increased frequencies of chromosomal aberrations, while SCEs were significantly increased at 4 of the 6 plants. High SCE values appeared with styrene air concentrations higher than 200 mg/mc. Apart from the possible presence and role of other interfering chemicals in the various plants, chromosomal aberrations seem to be more sensitive than SCEs for the detection of chromosomal damage caused by exposure to low doses of styrene.     

Streptonigrin induces delayed chromosomal instability involving interstitial telomeric sequences in Chinese hamster ovary cells

We analyzed the induction of chromosomal aberrations in Chinese hamster ovary (CHO) cells exposed to the radiomimetic compound streptonigrin (SN), in order to determine whether interstitial telomeric sequences (ITSs) are involved in the long-term clastogenic effect of this antibiotic. CHO cells were treated with a single concentration of SN (100ng/ml), and the frequency of unstable chromosomal aberrations was determined at three times after treatment (18h, and 6 and 15 days) by using PNA-FISH with a pan-telomeric probe. Cytogenetic analysis revealed a higher frequency of aberrations at 18h and 6 days after treatment in SN-exposed cultures vs. untreated cultures. The percentage of damaged cells and the yield of SN-induced aberrations at 6 days after treatment increased on average twofold compared with the ones at 18h after treatment. Moreover, a significant decrease in the frequency of aberrations was observed in SN-exposed cells at 15 days after treatment, resulting in a frequency of aberrations significantly lower than the frequency of aberrations observed in the corresponding control cultures. These data indicate that SN induces delayed chromosomal instability in CHO cells, and that the in vitro clastogenic effect of this compound persists for at least 6 days but less than 15 days after treatment. In addition, we found that SN induces delayed ITSs instability, cytogenetically detectable as additional FISH signals and centromeric breaks involving dissociation of the telomeric signal 6 days after treatment. We propose that the delayed effect of SN on ITSs results from breakage of heterochromatic centromeric ITSs blocks and further insertion of these sequences at the sites of mono- or isochromatid breaks occurring at G2 or G1-S phases of the cell cycle, respectively, since most of the additional FISH signals were present as single or double dots, and located at interstitial sites of the involved chromosomes.     

Frequency of chromosome aberrations induced in human peripheral lymphocytes by in vitro 60Co gamma quanta at doses of 1 to 5 Gr. in an analysis of the 1st-division cells at different fixation times

The quantitative analysis of chromosomal aberrations in the first division cells of 50-, 54-, 58-, 52- and 66-hour peripheral blood lymphocytes cultures of healthy donors was performed after irradiation in vitro with 60Co gamma-quantums at doses 1--5 Gy. Cells of the first division were identified by a differential staining of sister chromatid method using 5-bromdeoxyuridine. No significant differences in frequencies of aberrant cells and aberrations of chromosomal type were found between cultures fixed at different times. The distribution of dicentrics in cells did not differ from the Poisson distribution regardless of fixation times and doses. On the basis of these findings it is concluded that chromosomes of human peripheral blood lymphocytes passing the cell cycle at different rates have approximately equal radiosensitivity.     

Spectrum of chromosomal aberrations in peripheral lymphocytes of hospital workers occupationally exposed to low doses of ionizing radiation

Chromosome aberrations frequency was estimated in peripheral lymphocytes from hospital workers occupationally exposed to low levels of ionizing radiation and controls. Chromosome aberrations yield was analyzed by considering the effects of dose equivalent of ionizing radiation over time, and of confounding factors, such as age, gender and smoking status. Frequencies of aberrant cells and chromosome breaks were higher in exposed workers than in controls (P = 0.007, and P = 0.001, respectively). Seven dicentric aberrations were detected in the exposed group and only three in controls, but the mean frequencies were not significantly different. The dose equivalent to whole body of ionizing radiation (Hwb) did appear to influence the spectrum of chromosomal aberrations when the exposed workers were subdivided by a cut off at 50 mSv. The frequencies of chromosome breaks in both subgroups of workers were significantly higher than in controls (< or =50 mSv, P = 0.041; >50 mSv, P = 0.018). On the other hand, the frequency of chromatid breaks observed in workers with Hwb >50 mSv was significantly higher than in controls (P = 0.015) or workers with Hwb < or =50 mSv (P = 0.046). Regarding the influence of confounding factors on genetic damage, smoking status and female gender seem to influence the increase in chromosome aberration frequencies in the study population. Overall, these results suggested that chromosome breaks might provide a good marker for assessing genetic damage in populations exposed to low levels of ionizing radiation.     

Cytogenetic effects of pulsing electromagnetic field on human lymphocytes in vitro: chromosome aberrations, sister-chromatid exchanges and cell kinetics

Exposure of human lymphocyte cultures to a pulsing electromagnetic field (PEMF; 50 Hz, 1.05 mT) for various durations (24, 48 and 72 h) resulted in a statistically significant suppression of mitotic activity and a higher incidence of chromosomal aberrations. Furthermore, the shorter exposure times (24 and 48 h) did not cause a significant delay in cell turnover (cell proliferation index) or an increase in the baseline frequency of sister-chromatid exchanges (SCE). However, cultures continuously exposed to PEMF for 72 h exhibited significant reduction of the cell proliferation index (CPI) and an elevation of SCE rate. These results suggest that exposure to PEMF may induce a type of DNA lesions that lead to chromosomal aberrations and cell death but not to SCE, except probably at longer exposure times.     

Cytogenetic effects of diazepam in peripheral lymphocytes of self-poisoned persons.

The frequencies of chromosomal aberrations and of micronuclei were determined in lymphocyte cultures of 25 patients who attempted suicide with diazepam, 6-12 h, 72 h and 30 days after self-poisoning. These data were compared with those of healthy controls. The frequencies of numerical aberrations showed a significant increase immediately after self-poisoning. However, this effect could not be detected on the 3rd and 30th days after self-poisoning.     

Detection of chromosomal instability in bystander cells after Si490-ion irradiation

There is increasing evidence that two of the biological effects associated with low-dose ionizing radiation, genomic instability and bystander responses, may be linked. To verify and validate the link between the two phenomena, the ability of Si490 ions (high-energy particles associated with radiation risk in space) to induce bystander responses and chromosomal instability in human bronchial epithelial (HBEC-3kt) cells was investigated. These studies were conducted at both the population and single cell level in irradiated and nonirradiated bystander cells receiving medium from the irradiated cultures. At the general population level, transfer of medium from silicon-ion (Si490)-irradiated cultures (at doses of 0.073?Gy, 1.2?Gy and 2?Gy) to nonirradiated bystander cells resulted in small increases in the levels of chromosomal aberrations at the first division. Subsequently, single cell clones isolated from irradiated and bystander populations were analyzed for the appearance of de novo chromosome-type aberrations after ～50 population doublings using mFISH. Both irradiated and bystander clones demonstrated chromosomal instability (as seen by the de novo appearance of translocations and chromosomal fragments), albeit to different degrees, whereas sham-treated controls showed relatively stable chromosomal patterns. The results presented here highlight the importance of nontargeted effects of radiation on chromosomal instability in human epithelial cells and their potential relevance to human health.     

Protective roles of exogenous polyamines on chromosomal aberrations in <Emphasis Type="Italic">Hordeum vulgare</Emphasis> exposed to salinity

The effects of exogenous polyamines (PAs): spermine (Spm), spermidine (Spd), cadaverine (Cad) and putrescine (Put) on mitotic activity and chromosomal aberrations in root meristem cells of Hordeum vulgare L. (barley) seeds exposed to salinity were analyzed. The PAs significantly inhibited cell division in distilled water. Furthermore, most of these PAs (except for Spd) caused a significant increase in the frequency of chromosomal aberrations as compared to control group. Seeds treated with Put caused the highest percentage of mitotic abnormalities in total. The negative effect of salinity on mitotic index and the frequency of chromosomal aberrations increased with increasing salt concentration. PAs studied could not be successful in ameliorating of the negative effect of salinity on mitotic activity. Particularly, exposure to Cad and 0.40 M NaCl caused a complete block of cell division in total. However, most of the PA studied showed a perfectly performance in alleviating the detrimental effects of increasing salinity on chromosomal aberrations.     

Chronic gamma-irradiation results in increased cell killing and chromosomal aberration with specific breakpoints in fibroblast cell strains derived from non-Hodgkin's lymphoma patients.

Cultured skin fibroblast cells from 6 patients with non-Hodgkin's lymphoma (NHL) and 2 clinically normal subjects were compared for cell survival and chromosomal aberration after chronic gamma-irradiation. Fibroblasts from an ataxia telangiectasia (AT) homozygote and an AT heterozygote were used as positive controls. Following irradiation, fibroblasts from all 6 NHL patients showed an increase in both cell death and chromosomal aberration (breaks and rearrangements) compared to the normal subjects. The difference in the frequency of chromosomal aberration between the normals and the NHL patients remained virtually unchanged over a period of 24-72 h post irradiation incubation of the cells. Cell cycle analysis by flow cytometry carried out in 1 normal and 1 NHL fibroblast cell strain showed that more cells representing the NHL patient were in G2/M phase compared to the normal at various times of cytogenetic analysis. While the AT homozygote appeared to be the most radiosensitive, the AT heterozygote showed a slightly higher incidence of cell death and chromosomal aberration than the normals. The cellular and chromosomal radiosensitivity of fibroblast cell lines from the NHL patients differed slightly from that of the AT heterozygote but clearly occupied an intermediate position between the AT homozygote and the normal subjects. Cells from 3 of the NHL patients showed radiation-induced specific chromosomal breaks involving chromosomes 1, 2, 6, 8, 10 and 11 which correspond to known fragile sites. Such breakpoints associated with increased radiosensitivity may be indicative of predisposition to malignancy in the patients studied.     

Chromosomal aberrations and sister-chromatid exchanges in Chinese hamster cells treated in vitro with hexavalent chromium compounds.

Chinese hamster cells (CHO line) were treated in vitro for 30--39 h with hexavalent chromium compounds (K2Cr2O7 and Na2CrO7), at concentrations ranging from 0.1 to 1.0 microgram of Cr6+ per ml, in medium containing BUdr. Chromosomal aberrations and sister-chromatid exchanges were scored on BUdr-labelled 2nd division metaphases, collected at the end of treatment and stained with Giemsa. Treatment with mitomycin C 0.009--0.030 microgram/ml) was carried out as a control for the responsiveness of the cell system to chromosomal damage. Both chromium compounds induced marked mitotic delays. Chromosomal aberrations were increased about 10-fold by exposure to Cr6+ (1.0 microgram/ml). The principal aberrations observed were single chromatid gaps, breaks and interchanges, whose frequencies increased proportionally to the concentration of chromium. Dicentric chromosomes, isochromatid breaks, chromosome and chromatid rings were also induced. The frequenyc of sister-chromatid exchanges was hardly doubled 30 h after exposure to Cr6+ at 0.3 microgram/ml, whereas it was trebled 39 h after treatment, in the cells whose division cycle had been slowed down by chromium.