Sister-chromatid exchanges in a special form of xeroderma pigmentosum (form II)

The frequency of sister-chromatid exchanges (SCE) was studied in peripheral blood lymphocytes from a xeroderma pigmentosum (form II, XPII) patient. The cells were irradiated with UV or X-rays. In some experiments novobiocin (NB), inhibitor of topoisomerase II, or caffeine (CA), inhibitor of DNA repair were added to the cultures. The level of spontaneous SCE in the patient's lymphocytes was found to be significantly increased in comparison to that in the cells from normal donors. The inhibitors and UV-light caused a rise in the frequency of SCE in the cells taken from normal donors and except for NB, in the lymphocytes from the patient XPII. X-Rays did not increase SCE frequency in normal lymphocytes and lowered it in the patient's cells. SCE frequency rose when inhibitors of DNA replication and repair were used in combination with mutagens.     

Frequencies of sister-chromatid exchanges in relation to cell kinetics in lymphocyte cultures

The frequency of sister-chromatid exchanges (SCE) was determined on second-division metaphase of lymphocytes stimulated by phytohaemagglutinin (PHA) during 9 days of culture.

By using either a continuous or a pulsed bromodeoxyuridine (BUdR) treatment, cells were selected that had divided only twice, or at least twice, after different culture periods. No significant differences were observed in the SCE frequencies among the various samples. The incidence of SCE appears to be independent of the proliferation properties of cultured lymphocytes, such as length of cell cycle, fast or delayed response to PHA and number of divisions performed in vitro.     

Changes in human EEG alpha activity following exposure to two different pulsed magnetic field sequences

The present study investigates the effects of a weak (+/-200 microT(pk)), pulsed, extremely low frequency magnetic field (ELF MF) upon the human electroencephalogram (EEG). We have previously determined that exposure to pulsed ELF MFs can affect the EEG, notably the alpha frequency (8-13 Hz) over the occipital-parietal region of the scalp. In the present study, subjects (n = 32) were exposed to two different pulsed MF sequences (1 and 2, used previously) that differed in presentation rate, in order to examine the effects upon the alpha frequency of the human EEG. Results suggest that compared to sham exposure, alpha activity was lowered over the occipital-parietal regions of the brain during exposure to Sequence 1, while alpha activity over the same regions was higher after Sequence 2 exposure. These effects occurred after approximately 5 min of pulsed MF exposure. The results also suggest that a previous exposure to the pulsed MF sequence determined subjects' responses in the present experiment. This study supports our previous observation of EEG changes after 5 min pulsed ELF MF exposure. The results of this study are also consistent with existing EEG experiments of ELF MF and mobile phone effects upon the brain.     

Experimental studies on extremely low frequency pulsed magnetic field inhibiting sarcoma and enhancing cellular immune functions

The previous observation with an electron microscope showed that extremely low frequency (ELF) pulsed magnetic field (PMF) (with the maximum intensity of 0. 6-2. 0 T, gradient of 10-100 T. M-1, pulse width of 20-200 ms and frequency of 0. 16-1. 34 Hz) inhibited the growth of S-180 sarcoma in mice and enhanced the ability of immune cell's dissolving sarcoma cells. In this study, the DNA contents of nuclei were assayed by using Faulgen Staining method. With an electron microscope and cell stereoscopy technology it was observed that magnetic field affected the sarcoma cell's metabolism, lowered its malignancy, and restrained its rapid and heteromorphic growth. The magnetic field enhanced the cellular immune ability and the reaction of lymphocytes and plasma. Since ELF pulsed magnetic fields can inhibit the growth of sarcomas and enhance the cellular immune ability, it is possible to use it as a new method to treat cancer.     

Cytogenetic studies of mice exposed to styrene by inhalation.

The data for the in vivo genotoxicity of styrene (STY) are equivocal. To evaluate the clastogenicity and sister-chromatid exchange (SCE)-inducing potential of STY in vivo under carefully controlled conditions, B6C3F1 female mice were exposed by inhalation for 6 h/day for 14 consecutive days to either 0, 125, 250 or 500 ppm STY. One day after the final exposure, peripheral blood, spleen, and lungs were removed and cells were cultured for the analysis of micronucleus (MN) induction using the cytochalasin B-block method, chromosome breakage, and SCE induction. Peripheral blood smears were also made for scoring MN in erythrocytes. There was a significant concentration-related elevation of SCE frequency in lymphocytes from the spleen and the peripheral blood as well as in cells from the lung. However, no statistically significant concentration-related increases were found in the frequency of chromosome aberrations in the cultured splenocytes or lung cells, and no significant increases in MN frequencies were observed in binucleated splenocytes or normochromatic erythrocytes in peripheral blood smears.     

Spontaneous and induced chromosomal instability in Werner syndrome

Summary In extension of a previous study, spontaneous and clastogen-induced chromosome damage was analyzed in cultures of peripheral blood lymphocytes from six further patients with Werner syndrome (WS) and six healthy controls. In addition, sister chromatid exchange (SCE) was estimated in four of these cases. Lymphocytes of patients with various other diseases were used for another series of control experiments. Diepoxybutane (DEB), 4-nitroquinoline-1-oxide (NQO), and bleomycin (BLM) were the standard clastogens throughout the study. While the spontaneous frequency of chromosomal breakage was significantly higher in lymphocytes from all the patients than in the control cells, the basis SCE rate was un-affected in WS cells. Sensitivity of WS cells to the chromosome-damaging action of BLM did not differ from that of control cells, and their sensitivity to DEB was slightly greater than that of control lymphocytes. However, NQO induced a more distinct increase of both break and interchange aberrations in the WS cells than in control cells or cells from patients with other diseases. This effect was not found for the SCE rate. Our data demonstrate the exceptional cytogenetic features of this syndrome: Although the spontaneous and the DEB- and NQO-induced chromosomal breakage rate would suggest that WS is like a classic chromosomal instability syndromes, the lack of sensitivity of WS cells to bleomycin and their stable SCE frequency compared with that of control cells clearly delimitate this syndrome from other entities.     

Induction of sister-chromatid exchange (SCE) and cell-cycle inhibition in mouse peripheral blood B lymphocytes exposed to mutagenic carcinogens in vivo

To determine the sensitivity of the mouse peripheral blood lymphocyte (PBL) culture system, male B6C3f1 mice were injected i.p. with either 2-acetylaminofluorene (AAF) (20, 40, 80, 160 mg/kg), benzo[a]pyrene (BP) 25, 75, 150, 300 mg/kg), dichlorvos (DCV) (5, 15, 25, 35 mg/kg), ethyl methanesulfonate (EMS) (10, 30, 90, 180, 270 mg/kg), or N-nitrosomorpholine (NM) (37.5, 75, 150, 300 mg/kg) dissolved in either RPMI 1640 (DCV, EMS, NM) or sunflower oil (AAF, BP). 24 h later blood was removed by cardiac puncture, and the lymphocytes were cultured in the presence of lipopolysaccharide for analysis of SCE in B lymphocytes. All 4 mutagenic carcinogens (AAF, BP, EMS, NM) induced significant dose-related increases in SCE frequency. DCV, a potent neurotoxicant, caused no change in the baseline SCE frequency. At the highest concentration of each chemical examined, AAF caused a 1.6-fold increase, EMS a 1.8-fold increase, NM a 3.0-fold increase, and BP a 3.1-fold increase in SCE frequency compared to concurrent controls. A comparison of these results for PBLs with those reported in the literature for bone marrow cells indicates that PBLs offer a good quantitative and qualitative estimate of the SCE-inducing potential for these 5 compounds in bone marrow cells.     

石油作业习惯性流产女性细胞遗传毒性研究

目的:研究石油作业环境对女性习惯性流产的遗传毒性。方法:随机选择习惯性流产的石油作业女性38人和正常的育龄女性20人,检测其外周血淋巴细胞姐妹染色单体互换,记数SCE发生率。结果:观察组的外周血淋巴细胞SCE发生率为8.81±0.35,明显高于对照组(P0.05)。结论:SCE的发生可作为石油作业习惯性流产女性染色体结构稳定性的检测指标。石油作业环境对女性生育具有遗传毒性。     

Sister-chromatid exchanges in lymphocytes of smokers in an experimental study

The frequency of sister-chromatid exchanges (SCEs) was studied in peripheral blood lymphocytes of 26 young male smokers and 10 non-smokers who had recently entered military service. The levels of SCEs were examined in 4 consecutive blood samples taken after short experimental periods of smoking only low-tar (LT) or medium-tar (MT) cigarettes. The incidence of SCEs was significantly higher in the the group of smokers than in the group of non-smokers. The SCE levels of the smokers were found to be associated with the personal smoking history; the observed increase in the SCE frequency correlated with the years of smoking measured as cumulative pack years. The difference in type of cigarette did not influence the SCE frequencies.     

A decreased frequency of sister chromatid exchanges in pregnant women

Sister chromatid exchanges (SCE) and cellular proliferation were studied in lymphocytes from 16 pregnant and 18 non-pregnant women. A lowered SCE frequency was found in lymphocytes obtained from pregnant women (9.41 +/- 0.39 vs. 11.07 +/- 0.42 SCE/metaphase in non-pregnant women). Lower proliferation rates were also common for cultures of pregnant women. Thus, physiological changes occurred in the organism of pregnant women may influence various cytogenetic indices registered in human peripheral blood cultures.     

石油作业习惯性流产女性细胞遗传毒性研究

目的：研究石油作业环境对女性习惯性流产的遗传毒性。方法：随机选择习惯性流产的石油作业女性38人和正常的育龄女性20人,检测其外周血淋巴细胞姐妹染色单体互换,记数SCE发生率。结果：观察组的外周血淋巴细胞SCE发生率为8．81＋0．35,明显高于对照组（P〈0．05）。结论：SCE的发生可作为石油作业习惯性流产女性染色体结构稳定性的检测指标。石油作业环境对女性生育具有遗传毒性。     

Differences in sister-chromatid exchange frequency between homologous chromosomes in Muntiacus muntjak.

The frequency of sister-chromatid exchanges (SCEs) on homologous autosomes was studied in the peripheral blood lymphocytes of the Indian muntjac. The homologous autosomes differed from one another with respect to the SCE frequency on them.     

Resting EEG effects during exposure to a pulsed ELF magnetic field

Continuing evidence suggests that extremely low frequency magnetic fields (ELF MFs) can affect animal and human behavior. We have previously demonstrated that after a 15 min exposure to a pulsed ELF MF, with most power at frequencies between 0 and 500 Hz, human brain electrical activity is affected as measured by electroencephalography (EEG), specifically within the alpha frequency (8-13 Hz). Here, we report that a pulsed ELF MF affects the human EEG during the exposure period. Twenty subjects (10 males; 10 females) received both a magnetic field and a sham session of 15 min in a counterbalanced design. Analysis of variance (ANOVA) revealed that alpha activity was significantly lower over the occipital electrodes (O1, Oz, O2) [F(1,16) = 5.376, P < .01, eta2 = 0.418] after the first 5 min of magnetic field exposure and was found to be related to the order of exposure (MF-sham vs. sham-MF). This decrease in alpha activity was no longer significant in the 1st min post-exposure, compared to sham (P > .05). This study is among the first to assess EEG frequency changes during a weak (+/-200 microTpk), pulsed ELF MF exposure.     

Biomarkers of genotoxicity and genomic instability in a non-human primate, Cebus libidinosus (Cebidae, Platyrrhini), exposed to nitroimidazole derivatives

The genotoxicity of two nitroimidazole derivatives, ornidazole (ONZ) and metronidazole (MTZ) in the peripheral blood lymphocytes of Cebus libidinosus (CLI) (Primates, Cebidae) was assessed. Endpoints measured included sister chromatid exchange (SCE) frequency, cell proliferation kinetics (CPK), replication index (RI), mitotic index (MI), and damage incidence in or near CLI heterochromatin regions. MI and SCE values following ONZ or MTZ treatments were significantly different (p<0.001) from control. SCE frequency per chromosome was not proportional to chromosome length. The chromosomes most affected for SCE were 1, 2, 4, 6, 11-13, 17, and 18, many of which possess interstitial or terminal heterochromatin. In the CLI genome, chromosomes 11 and 17 showed higher susceptibility to damage RI was the only biomarker that did not show statistically significant differences between control and treated cultures. C. libidinosus bands 11q1.4 and 11q1.5 may be hot-spots in the context of nitroimidazole exposure.     

Genetic aspects of nonchromaffin paraganglioma

Summary Sister chromatid exchanges (SCE) and structural chromosome aberrations were analyzed in peripheral blood lymphocytes of 100 individuals, and correlated to age and sex. No correlation was found between the frequency of SCE and age, but older individuals had significantly more structural aberrations than younger. Females had significantly more SCE as well as structural chromosome aberrations than males. The positive correlations of SCE and structural aberrations to age and sex were also significant when these factors, as well as smoking habits, were taken into consideration in an analysis of covariance.     

An evaluation of the feasibility of using cytogenetic damage as a biomarker for alachlor exposure

Alachlor is a widely used herbicide for which there is significant human exposure, principally through groundwater contamination and inhalation. Because alachlor is purported to be carcinogenic and mutagenic, we initiated studies to determine if induced cytogenetic damage could be used as a biomarker for exposure to this herbicide. Both isolated and whole blood human lymphocytes were exposed to alachlor using several protocols. The lymphocytes were cultured for analysis of sister chromatid exchange (SCE), chromosome aberrations (CAs), micronuclei (MN) in cytochalasin B-induced binucleated cells, and proliferation kinetics using the replicative index (RI). In addition, CD rats were injected with either 10 or 50 mg kg-1 of alachlor, 2-chloro-N-(2,6-diethylphenyl) acetamide (CDEPA) or 2, 6-diethylanaline (DEA). After 24 h, the peripheral blood lymphocytes were removed and cultured for SCE and RI analysis. Alachlor did induce a concentration-related increase in SCE in vitro, but neither it nor its metabolites (CDEPA or DEA) induced a significant increase in SCEs or an alteration of RI in vivo. At the highest in vitro concentration tested, alachlor induced a statistically-significant increase in MN, but no concomitant increase in CAs was seen. From analyses of our data and the literature on alachlor clastogenicity and exposure levels, we concluded that cytogenetic damage may not be an adequately sensitive marker for evaluating human exposure to alachlor.     

Analysis of sister chromatid exchanges in lymphocytes cultured from 71 healthy men

Sister chromatid exchanges (SCE) were analyzed in peripheral blood lymphocytes from a select group of 71 healthy men, 56 nonsmokers and 15 cigarette smokers. In addition to estimating baseline SCE, data were examined to seek relationships of SCE frequencies to age and smoking. The baseline value of 7.53 SCE per cell from the 56 nonsmokers was within the range (5.60 to 9.10 SCE/cell) reported for other human populations. No relationship was found between the mean SCE frequency per cell and age. However, a significant increase in the SCE mean value was observed in smokers as compared to nonsmokers. The results of this study are compared with those of other reports on SCE effects of age and smoking.Abbreviations BUdR 5-bromo,2-deoxyuridine - SCE sister chromatid exchange     

Increased frequency of acetaldehyde-induced sister-chromatid exchanges in human lymphocytes treated with an aldehyde dehydrogenase inhibitor

Acetaldehyde, the first metabolite of ethanol oxidation, in concentrations ranging from 100 microM to 400 microM caused a dose-dependent linear increase in the frequency of sister-chromatid exchanges (SCE) in cultured human peripheral lymphocytes. The SCE frequency was on an average 2-fold higher when the cells were exposed to the acetaldehyde after 24 h incubation instead of at the time of mitogen stimulation (0 h). When acetaldehyde was added together with the potent aldehyde dehydrogenase inhibitor 1-aminocyclopropanol (0.1 mM), the SCE response was significantly (p less than 0.05) increased. The present results indicate that acetaldehyde is metabolized within human lymphocytes, and, moreover, that alcohol consumption during treatment with drugs that inactivate aldehyde dehydrogenase may cause a further increased incidence of acetaldehyde-induced SCE and concomitant lesions.     

Effects of a 60 Hz magnetic field on photosynthetic CO2 uptake and early growth of radish seedlings

Photosynthetic CO2 uptake rate and early growth parameters of radish Raphanus sativus L. seedlings exposed to an extremely low frequency magnetic field (ELF MF) were investigated. Radish seedlings were exposed to a 60 Hz, 50 microT(rms) (root mean square) sinusoidal magnetic field (MF) and a parallel 48 microT static MF for 6 or 15 d immediately after germination. Control seedlings were exposed to the ambient MF but not the ELF MF. The CO2 uptake rate of ELF MF exposed seedlings on day 5 and later was lower than that of the control seedlings. The dry weight and the cotyledon area of ELF MF exposed seedlings on day 6 and the fresh weight, the dry weight and the leaf area of ELF MF exposed seedlings on day 15 were significantly lower than those of the control seedlings, respectively. In another experiment, radish seedlings were grown without ELF MF exposure for 14 d immediately after germination, and then exposed to the ELF MF for about 2 h, and the photosynthetic CO2 uptake rate was measured during the short-term ELF MF exposure. The CO2 uptake rate of the same seedlings was subsequently measured in the ambient MF (control) without the ELF MF. There was no difference in the CO2 uptake rate of seedlings exposed to the ELF MF or the ambient MF. These results indicate that continuous exposure to 60 Hz, 50 microT(rms) sinusoidal MF with a parallel 48 microT static MF affects the early growth of radish seedlings, but the effect is not so severe that modification of photosynthetic CO2 uptake can observed during short-term MF exposure.