盐胁迫浓度与大麦幼苗生长分裂和遗传损伤的相关性研究

研究盐胁迫浓度与大麦幼苗生长分裂的关系, 实验结果表明:大麦幼苗生长在一定浓度的NaCl 溶液中时, 幼苗生长抑制、叶绿素含量降低, 有丝分裂指数下降, 根尖分生区细胞中具有微核和染色体畸变的细胞明显增多。统计分析结果显示:幼苗的分裂指数、遗传损伤与盐浓度间有很好的线性关系, 有丝分裂指数与处理浓度间呈负相关(p < 0.01), 微核率、染色体畸变率两项指标与处理浓度间呈正相关(p < 0.01)。研究结果表明:大麦幼根有丝分裂指数、微核率及染色体畸变率可以作为监测环境NaCl 的定量指标。     

Clastogenic effect of ethanol in chronic and abstinent alcoholics

Alcoholism is one of the main causes of damage for human health, being relevant to study the induction of chromosomal aberrations (CA) by ethanol, and to investigate the individual susceptibility to diseases caused by alcoholism. A cytogenetic study was performed in human peripheral blood lymphocytes of 29 heavy chronic alcoholics, 11 alcoholics in abstinence, and 10 controls. The values of the chromosomal aberrations, mitotic indexes (MI) and proliferation indexes (PI) were determined. A molecular cytogenetic study was also carried out using fluorescence in situ hybridization (FISH) method with DNA library probes for chromosomes 1, 3 and 6, in lymphocytes from chronic alcoholic individuals in comparison with a control group. The results showed that the CA frequencies for chronic alcoholics (5.15 CA/100 cells) and alcoholics in abstinence (3.87 CA/100 cells) were higher than those obtained for control individuals (1.72 CA/100 cells). The mean translocation frequencies (equivalent to the genome) were calculated for six chronic alcoholics (0.267 translocations/100 cells) and six alcoholics in abstinence (0.167 translocations/100 cells), whose values were significantly higher than those observed for six control individuals (0.067 translocations/100 cells). The CA frequencies were not statistically different when smoker and non-smoker alcoholics were compared, indicating that although the smoking habit had significantly increased (four-fold) the CA frequency in healthy control individuals, a lack of interaction effect was observed within the group of alcoholics when smokers and non-smokers were compared. The CA frequencies presented by alcoholics in abstinence were similar to those obtained for chronic alcoholics. Therefore, chronic ethanol intoxication can lead to chromosome damage and disturbances in the metabolism of endogenous and exogenous compounds, which may persist for a long time, and constitute a relevant factor of risk for the development of neoplasias.     

The induction of chromosomal aberrations by tetra antibiotic in bone marrow cells of rats in vivo

The aim of this study was to investigate the in vivo effects of Tetra (Tetralet) antibiotic on the chromosomal aberrations (CA) in bone marrow cells of rats (Rattus norvegicus var. albinos). Tetra antibiotic significantly increased the percentage of abnormal cells and the chromosomal aberrations per cells (CA/cell) in bone marrow cells of rats at concentrations of 100 and 200 mg/kg body weight for 12 and 24 hours treatment periods for each. In addition, the percentage of abnormal cells and the CA/cell increased dose-dependently for 12 hours treatment period; In contrast, mitotic index (MI) was decreased when compared with negative control and solvent controls for 12 hours treatment period. However, MI increased depend on Tetra antibiotic dose for 24 hour treatment period.     

Clastogenic effect of ethanol in chronic and abstinent alcoholics

Alcoholism is one of the main causes of damage for human health, being relevant to study the induction of chromosomal aberrations (CA) by ethanol, and to investigate the individual susceptibility to diseases caused by alcoholism. A cytogenetic study was performed in human peripheral blood lymphocytes of 29 heavy chronic alcoholics, 11 alcoholics in abstinence, and 10 controls. The values of the chromosomal aberrations, mitotic indexes (MI) and proliferation indexes (PI) were determined. A molecular cytogenetic study was also carried out using fluorescence in situ hybridization (FISH) method with DNA library probes for chromosomes 1, 3 and 6, in lymphocytes from chronic alcoholic individuals in comparison with a control group. The results showed that the CA frequencies for chronic alcoholics (5.15 CA/100 cells) and alcoholics in abstinence (3.87 CA/100 cells) were higher than those obtained for control individuals (1.72 CA/100 cells). The mean translocation frequencies (equivalent to the genome) were calculated for six chronic alcoholics (0.267 translocations/100 cells) and six alcoholics in abstinence (0.167 translocations/100 cells), whose values were significantly higher than those observed for six control individuals (0.067 translocations/100 cells). The CA frequencies were not statistically different when smoker and non-smoker alcoholics were compared, indicating that although the smoking habit had significantly increased (four-fold) the CA frequency in healthy control individuals, a lack of interaction effect was observed within the group of alcoholics when smokers and non-smokers were compared. The CA frequencies presented by alcoholics in abstinence were similar to those obtained for chronic alcoholics. Therefore, chronic ethanol intoxication can lead to chromosome damage and disturbances in the metabolism of endogenous and exogenous compounds, which may persist for a long time, and constitute a relevant factor of risk for the development of neoplasias.     

Aroclor-1254-induced rat-liver S9 causes chromosomal aberrations in CHO cells but not human lymphocytes: a role for active oxygen?

Incubation of CHO cells with Aroclor-1254 induced S9 mix gave higher than normal levels of chromosomal aberrations (CA), sometimes achieving exceptional levels (e.g. up to 40 CA, minus gaps, per 100 cells against a normal range of 0-10). The same batches of S9 gave normal CA frequencies in human lymphocytes from whole blood cultures, normal mutation frequencies in bacterial reversion (Ames) tests and mammalian cell hgprt mutation tests, and normal levels of repair in scheduled DNA synthesis tests. As cytochrome P-450 enzymes, in the absence of substrate, will cycle electrons and could produce active oxygen species (AOS), which are known to be clastogenic, this was investigated. Preliminary studies showed the complete S9 mix was required for the high levels of CA, and that CA levels could be dramatically reduced by co-incubation with catalase or vitamin E. Interestingly, uninduced S9 and phenobarbitone/beta-naphthoflavone induced S9 mixes did not cause high levels of CA, and presumably have different isozymes of P-450 that do not generate AOS as readily. These observations suggest that CHO cells are sensitive to AOS which are inactivated by blood components. This may have implications for the choice of cell system in routine clastogenicity testing of novel chemicals.     

Louis-Bar syndrome: spontaneous and induced chromosomal aberrations in lymphocytes and micronuclei in lymphocytes,oral mucosa and hair root cells

Summary Louis-Bar (L-B) syndrome, also called ataxia-telangiectasia, is cytogenetically characterized by an increased frequency of spontaneous and induced chromosomal aberrations (CA) in cultured lymphocytes and skin fibroblasts. However, it is not yet clear whether the chromosomal instability is also present in uncultured cells. The spontaneous and bleomycin-induced CA in peripheral lymphocytes of 8 L-B patients were evaluated. The micronucleus test was also performed, for the first time in lymphocytes by the cytokinesis-block method, and in uncultured cells of the oral cavity and hair root. The spontaneous frequency of CA and micronuclei in lymphocytes was about 3 times higher in L-B patients than in controls, these two cytogenetic parameters being highly correlated. Moreover, the induction by bleomycin of CA was higher in patients than in controls. The micronuclei in buccal and hair root cells of patients were normal. It remains to be determined whether the different responses obtained with cultured and uncultured cells are the result of the different L-B gene expression of chromosomal instability or whether they arise because of a particular cell sensitivity to culture conditions. The spontaneous and induced CA in lymphocytes of heterozygotes cultured in the presence of L-B serum were studied to evaluate a possible increased sensitivity of heterozygotes to a possible diffusible clastogenic factor present in the plasma of L-B patients. We could not demonstrate the presence of any factor that enhances CA in normal subjects or in heterozygote carriers.     

The Induction of Chromosomal Aberrations by Tetra Antibiotic in Bone Marrow Cells of Rats in Vivo

The aim of this study was to investigate the in vivo effects of tetra (tetralet) antibiotic on chromosomal aberrations (CA) in bone marrow cells of rats (Rattus norvegicus var. albinos). The tetra antibiotic significantly increased the percentage of abnormal cells and the chromosomal aberrations per cell (CA/cell) in bone marrow cells of rats at concentrations of 100 and 200 mg/kg body weight for 12 and 24 h treatment periods for each. In addition, the percentage of abnormal cells and the CA/cell increased dose-dependently for 12 h treatment period; in contrast, mitotic index was decreased when compared with negative control and solvent controls for 12-h treatment period. However, mitotic index increased depending on tetra antibiotic dose for 24-h treatment period.     

Genotoxic effects in M5 cells and Chinese hamster V79 cells after exposure to 7Li-beam (LET=60 keV/microm) and correlation of their survival dynamics to nuclear damages and cell death

Chinese hamster V79 cell and a cell strain M5, derived from V79 cells and reported to be relatively resistant to gamma-ray, hydrogen peroxide, and N-methyl-N-nitro-N-nitrosoguanidine (MNNG; a potent human carcinogen), were exposed to high LET (7)Li-beam (LET=60 keV/microm) at approximately 90% confluent state in the dose range of 0-1 Gy. Effects of (7)Li-beam exposure on cell survival, micronuclei induction (MN), chromosomal aberrations (CA) and apoptosis were compared in both the cell lines. A dose-dependent decline in survival for both the cell lines was noted, relatively less in M5 cells (mostly p<0.01) indicating greater radio-resistance in this strain. The MN, CA and apoptosis increased in a dose-dependent manner in both V79 and M5 cells. Significant differences in various other parameters between these two cell lines were also noted. The relative intensity of DNA ladder, which is a useful marker for the determination of the extent of apoptosis induction, was much higher in V79 cells. A good correlation between the reduction of the surviving fractions and the increase in frequencies of MN or CA or apoptosis was noted for both the cell lines.     

Evaluation of chromosomal aberrations in lymphocytes and micronuclei in lymphocytes, oral mucosa and hair root cells of patients under antiblastic therapy

In 7 patients undergoing antiblastic chemotherapy for the first time, the structural chromosomal aberration (CA) test in peripheral lymphocytes was compared with the micronucleus (Mn) test in lymphocytes, in oral cavity cells and in hair root cells of the scalp. The last test is being proposed for the first time. The CA and Mn frequencies induced by chemotherapy were compared with the baseline (pretreatment) frequencies of the patients and with confidence limits calculated in 4 control groups studied for CA, Mn in lymphocytes, Mn in oral cavity cells and Mn in hair root cells, respectively. The studied chemotherapies induced a clear cytogenetic effect in at least 2 of the tests studied with the exception of interferon-alpha 2b (patient 6) and interferon + low doses of cis-platinum (patient 2) which did not appear to cause evident chromosomal damage. The response to chemotherapy is generally characterized by an increase in Ca and Mn, reaching a peak value and then decreasing in the following weeks. The CA test proves to be the most sensitive despite the fact that CA were analyzed in an average of 100 cells per sample against the 500-3000 cells analyzed for Mn. The efficiency of Mn to detect CA is in the following order: Mn in lymphocytes greater than Mn in buccal cells greater than Mn in hair root cells. The last test appears to be very promising but, used following the current method, does not appear suitable to monitor acute exposure.     

Chromosomal aberrations and risk of cancer in humans: an epidemiologic perspective

The pioneering papers published more than one century ago by Theodor Boveri opened the way to extensive research on the mechanism linking chromosomal abnormalities to the pathogenesis of cancer. As a result of this effort, robust theoretical and empirical evidence correlating cytogenetic damage to early stages of cancer in humans was consolidated, and an increased cancer risk was postulated in healthy subjects with high levels of chromosomal aberrations (CA). The first epidemiological investigation aimed at validating CA as predictor of cancer risk was carried out in the early 1990s. In that report the Nordic Study Group described an 80% increased risk of cancer in healthy subjects with high frequencies of CA. The results of this first study were replicated a few years later in a parallel research initiative carried out in Italy, and the subsequent pooled analysis of these two cohorts published in 1998 contributed to refine the quantitative estimate of the CA/cancer association. A small case-control study nested in a cohort of subjects screened for CA in Taiwan found an increased risk in subjects with high frequency of chromosome-type CA, while in 2001 a significant increase of cancer incidence associated with high levels of CA was described in a new independent cohort of radon exposed workers from the Czech Republic. Despite some common limitations affecting study design, the studies cited above have provided results of great interest both for the understanding of mechanisms of early stages of carcinogenesis, and for their potential implication for cancer prevention. The recent evolution of molecular techniques and the refinement of high throughput techniques have the potential to improve the knowledge about the role of specific sub-types of CA and to provide further insight into the mechanisms. Finally, the most challenging perspective in the field is the passage from research to regulation, with the implementation of preventive policies based on the accumulated knowledge.     

Spontaneous and induced chromosome instability in patients with fragile X syndrome

Spontaneous and degranol- and dimatiph-induced chromosomal instability in the lymphocyte culture of patients with fra-X syndrome was investigated. The cultures contained TC 199 and 5% FC serum. It was found that the frequency of spontaneous chromosomal aberrations (CA) was 7.3% in cells from patients with fra(X), 3.9% in patients with MR of unknown origin, and 1.3% in normal individuals. Spontaneous break-points in the patients with fra(X) were localized in 1p, 2q, 3p, 6q, 7q, 16 q more often than in normal individuals. No significant difference was found in SCEs. The cells of patients with fra(X) were not sensitive to the induction of CA by degranol. It was found that chromosomal telomeric changes (CTC) were mutagen-independent, remaining at the spontaneous level: in the patients with fra(X) CTC were 10.5% (9.5% fra-Xq27, and 1% autosomal telomeric changes); in normal individuals CTC were 0.1%.     

Relevance of chemical structure and cytotoxicity to the induction of chromosome aberrations based on the testing results of 98 high production volume industrial chemicals

Over a 6-year period (1991-1996), the chromosomal aberration testing of high production volume (HPV) industrial chemicals had been conducted using Chinese hamster lung (CHL/IU) cells according to OECD HPV testing program and the national program in Japan. A total of 98 chemicals were tested for the induction of chromosome aberration (CA), consisting of structural CA and polyploidy. Of the 98 chemicals, structural CA and/or polyploidy were induced by 39 chemicals (40%). Anilines and phenols tended to induce only structural CA. p-tert-Butylphenol had a peculiar feature in inducing not only structural CA but also polyploidy at considerably high frequency (93.2%) after continuous treatment for 48 h, posing an aneugenic potential. Not all, but six of 11 carboxylic acids or esters also showed the simultaneous induction of structural CA and polyploidy. The majority of organic phosphates, alcohols or ethers, alkyl benzenes and non-cyclic alkanes had no CA induction activity. For chemicals which were negative in the bacterial reverse mutation assay (Ames test), the proportion of the chemicals that induced CA at a severely cytotoxic dose (doses manifesting more than 50% cytotoxicity) was similar to that of the CA-negative chemicals manifesting severe cytotoxicity, suggesting that severely cytotoxic chemicals do not always induce CA.     

The use of multiple sampling times in in vitro chromosome assays

Asynchronously growing V79 hamster cells were treated with hypotonic solutions of different osmolalities, with ethyl methanesulfonate (EMS) or a combination of these 2 agents. Four different fixation times (8, 10, 14, 18 h) were tested. Hypotonic treatment alone induced chromosomal aberrations (CA), leading to very high frequencies at low osmolalities (50 mOsm/kg H₂O). EMS also induced CA, but a comparison of EMS and hypotonicity revealed that EMS induced fewer aberrations at teh maximum doses tested. A combined treatment produced contradictory results, depending on the sampling time: 8 and 14 h led to a clear elevation of EMS-induced CA by hypotonicity, 10- and 18-h sampling times led to a decrease in the aberration frequency in EMS and hypotonically treated cells.

The observation that the choice of sampling time significantly influences the incidence of chromosomal aberrations is of particular interest for in vitro assays. In this study the 4 different sampling times are not enough to allow meaningful conclusions about additive or synergistic effects of the mutagens tested. These contradictory results are caused, on the one hand, by the very steep dose-response curve after hypotonic treatment and on the other hand by the varying degree of cell-cycle delay after combination treatment. This makes a valid comparison of teh CA frequencies impossible because no 2 sampling times contain the same mixture of cells.     

Increased frequency of chromatid breaks in lymphocytes of heterozygotes of ataxia telangiectasia after in vitro treatment with caffeine

The frequencies of caffeine-induced chromosomal aberrations (CA), mainly chromatid (CdB) and chromosome (CB) breaks, were studied in lymphocyte cultures derived from 6 obligatory heterozygotes and 1 homozygote of ataxia telangiectasia (AT), and from 4 control adult healthy persons. Caffeine (CF, 1 mM) was added at the beginning of the cultures exposed to CF the frequency of CB was 1.9% and of CdB 1.3%. In cells of the AT homozygote, the frequency of CdB was 6.8% in the absence and 8.7% in the presence of caffeine, the frequencies of CB being 3.4 and 10.9%, respectively. In AT heterozygous cells treated with CF, CdB increased 13-fold as compared to a less than 3-fold increase in control cells. Comparing the frequencies of CF-induced chromosomal lesions in control and AT heterozygous cells, potentiation factors (Pf) for the effect of 1 AT gene on cell sensitivity of CF (Pf [AT]) were 3.5 for CB, 6.6 for CdB and 5.5 for CA. These data demonstrate that lymphocytes of AT heterozygotes are significantly more sensitive to caffeine treatment in vitro in terms of increased frequency of CdB than normala cells, which may be useful for the diagnosis of carriers of this defective gene.     

Influence of Neurospora endonuclease on trenimon-induced structural chromosomal aberrations and sister-chromatid exchanges in human peripheral lymphocytes and Chinese hamster ovary cells

Human peripheral lymphocytes and Chinese hamster ovary cells were treated in the G1 phase of the cell cycle with the trifunctional alkylating agent trenimon (TRN) and post-treated with a single-strand specific endonuclease from Neurospora crassa (NE). TRN induces chromosomal aberrations of the chromatid type (CA) and sister-chromatid exchanges (SCE). NE post-treatment leads to an elevation of the frequencies of CA but not of SCEs. This indicates that TRN induced CA are the result of DNA double-strand breaks and that the SCEs originate from other types of lesions, most probably base damage.     

Genotoxicity of the cancer chemopreventive drug candidates CP-31398, SHetA2, and phospho-ibuprofen

The genotoxic activities of three cancer chemopreventive drug candidates, CP-31398 (a cell permeable styrylquinazoline p53 modulator), SHetA2 (a flexible heteroarotinoid), and phospho-ibuprofen (PI, a derivative of ibuprofen) were tested. None of the compounds were mutagenic in the Salmonella/Escherichia coli/microsome plate incorporation test. CP-31398 and SHetA2 did not induce chromosomal aberrations (CA) in Chinese hamster ovary (CHO) cells, either in the presence or absence of rat hepatic S9 (S9). PI induced CA in CHO cells, but only in the presence of S9. PI, its parent compound ibuprofen, and its moiety diethoxyphosphoryloxybutyl alcohol (DEPBA) were tested for CA and micronuclei (MN) in CHO cells in the presence of S9. PI induced CA as well as MN, both kinetochore-positive (Kin+) and -negative (Kin-), in the presence of S9 at ≤100μg/ml. Ibuprofen was negative for CA, positive for MN with Kin+ at 250μg/ml, and positive for MN with Kin- at 125 and 250μg/ml. DEPBA induced neither CA nor MN at ≤5000μg/ml. The induction of chromosomal damage in PI-treated CHO cells in the presence of S9 may be due to its metabolites. None of the compounds were genotoxic, in the presence or absence of S9, in the GADD45α-GFP Human GreenScreen assay and none induced MN in mouse bone marrow erythrocytes.     

A clinical overview of centrosome amplification in human cancers

The turn of the 21st century had witnessed a surge of interest in the centrosome and its causal relation to human cancer development - a postulate that has existed for almost a century. Centrosome amplification (CA) is frequently detected in a growing list of human cancers, both solid and haematological, and is a candidate "hallmark" of cancer cells. Several lines of evidence support the progressive involvement of CA in the transition from early to advanced stages of carcinogenesis, being also found in pre-neoplastic lesions and even in histopathologically-normal tissue. CA constitutes the major mechanism leading to chromosomal instability and aneuploidy, via the formation of multipolar spindles and chromosomal missegregation. Clinically, CA may translate to a greater risk for initiation of malignant transformation, tumour progression, chemoresistance and ultimately, poor patient prognosis. As mechanisms underlying CA are progressively being unravelled, the centrosome has emerged as a novel candidate target for cancer treatment. This Review summarizes mainly the clinical studies performed to date focusing on the mechanisms underlying CA in human neoplasia, and highlights the potential utility of centrosomes in the diagnosis, prognosis and treatment of human cancers.     

Genotoxic damage in Maras powder consumers from Kahramanmaras province of Turkey

In the present study, chromosomal aberrations (CAs) and micronucleus (MN) levels in the lymphocytes from 60 male individuals consisting of 40 habitues of Maras powder (a kind of smokeless tobacco) and 20 unexposed subjects were determined to investigate the possible inducing effect of Maras powder. The consumers of Maras powder had no exposure to any other known mutagens or toxicants. The mean exposure period to Maras powder was 12.25 + 0.93 years (range 3-22). Data obtained from microscopic examination of the slides was analyzed by SPSS (10.0) package programme. Mean frequency of CA and MN was found to be significantly higher in Maras powder consumers as compared to controls. Similarly, there was a significant elevation in the level of aberrant cells (Ab.Cells) with CAs and binucleated cells with MN (BNMN) in habitues. Spearman's rho correlation analysis indicated a significant increase in the frequency of CA and MN with increase in both age and years of exposure in consumers. Our finding of a significant elevation of CA and MN frequencies in peripheral lymphocytes from smokeless tobacco consumers demonstrated a potential cytogenetic hazard associated with Maras powder exposure.     

A cytogenetic study of men environmentally and occupationally exposed to airborne pollutants.

The level of sister-chromatid exchanges (SCE), high-frequency cells (HFC), chromosomal aberrations (CA) as well as the proliferation rate index (PRI) were measured in peripheral blood lymphocytes from three groups of volunteers. The environmentally exposed donors were residents from the vicinity of a coke factory; the occupationally exposed persons were cokery workers, while rural region inhabitants served as a control group. Compared with the control group, statistically significant increases of SCE and HFC, as well as decreased cell kinetics (PRI) were observed for both occupationally and environmentally exposed groups. The effect was especially pronounced when only smokers were taken into account. A statistically significant increase of CA was observed in the environmentally exposed group when CA including gaps (CA + G) were evaluated. The proportion of HFC was found to be the most sensitive method to detect genetic effects on the tested human population. This study demonstrates the usefulness of all 4 biomarkers (SCE, HFC, CA and PRI) in monitoring populations exposed to ambient pollution and clearly indicates effects from residential as well as occupational exposure to industrial air pollutants.