The induction of chromosome aberrations in human purified peripheral blood lymphocytes following in vitro exposure to selenium

Human lymphocyte cultures were treated with increasing concentrations (8.0 X 10(-8) M to 8.0 X 10(-5) M) of sodium selenite and selenomethionine 24 h after stimulation with phytohemagglutinin and were scored for chromosomal aberrations at 48 h. The yield of abnormal metaphases was dependent on the dose and the form of selenium used. At 8.0 X 10(-5) M the proportion of aberrant cells reached 53.5% and 43.0% for selenite and selenomethionine, respectively. The selenium-induced chromosomal aberrations were primarily of the chromatid type and included breaks and fragments. Chromosomal exchanges were less frequent and included triradials and quadriradials. These results confirm that selenium is clastogenic for cultured human lymphocytes.     

Persistence of drug-induced chromosome aberrations in peripheral blood lymphocytes of the rat

We have studied the persistence of pre-clastogenic lesions, detected as induced chromosomal aberrations, in rat peripheral lymphocytes at various time intervals after acute treatment with 3 different antineoplastic drugs: cyclophosphamide (CPA), 5-fluorouracil (5-FU) and adriamycin (AM). Single i.p. doses were administered to groups of rats and heart blood samples from each group were taken after 3, 12, 24 or 48 h or weekly up to 20 weeks later. The cytogenetic analysis was performed on lymphocytes cultured for 33 h after sampling. The results for CPA exposure (10 mg/kg) show that the yield of chromosome aberrations is maximal 3 h after the treatment (20 times the control level). For up to 8 weeks the values remain about 6 times the baseline; afterwards a decrease is observed and the control level is reached after 20 weeks. For 5-FU (50 mg/kg) a remarkable increase (13-fold) in chromosomal damage is observed at the first sampling time. Within 48 h the effect is drastically reduced but persistent (3 times the control level), and the level returns to spontaneous values 1 week later. AM treatment (2 mg/kg) induced an increase of about 8 times the control level at 3 h post exposure. The clastogenic effects remained at a detectable level for 1 week (about 6 times the control level at all sampling times); 2 weeks after the treatment the control level was found. A parallel analysis was performed on bone marrow cells. In this tissue the clastogenic effects of the treatments were maximal, as in lymphocytes, at the first sampling time (20-25 times the control level) and were no longer detectable within 72 h after exposure, irrespective of the administered drug.     

Spontaneous and radiation-induced chromosomal instability and persistence of chromosome aberrations after radiotherapy in lymphocytes from prostate cancer patients

The aim of the study was to compare the spontaneous and ex vivo radiation-induced chromosomal damage in lymphocytes of untreated prostate cancer patients and age-matched healthy donors, and to evaluate the chromosomal damage, induced by radiotherapy, and its persistence. Blood samples from 102 prostate cancer patients were obtained before radiotherapy to investigate the excess acentric fragments and dicentric chromosomes. In addition, in a subgroup of ten patients, simple exchanges in chromosomes 2 and 4 were evaluated by fluorescent in situ hybridization (FISH), before the onset of therapy, in the middle and at the end of therapy, and 1 year later. Data were compared to blood samples from ten age-matched healthy donors. We found that spontaneous yields of acentric chromosome fragments and simple exchanges were significantly increased in lymphocytes of patients before onset of therapy, indicating chromosomal instability in these patients. Ex vivo radiation-induced aberrations were not significantly increased, indicating proficient repair of radiation-induced DNA double-strand breaks in lymphocytes of these patients. As expected, the yields of dicentric and acentric chromosomes, and the partial yields of simple exchanges, were increased after the onset of therapy. Surprisingly, yields after 1 year were comparable to those directly after radiotherapy, indicating persistence of chromosomal instability over this time. Our results indicate that prostate cancer patients are characterized by increased spontaneous chromosomal instability. This instability seems to result from defects other than a deficient repair of radiation-induced DNA double-strand breaks. Radiotherapy-induced chromosomal damage persists 1 year after treatment.     

The incidence of unstable chromosome aberrations in peripheral blood lymphocytes from unirradiated and occupationally exposed people

Peripheral blood lymphocytes from unirradiated control subjects and workers exposed within permitted limits to γ-radiation, have been examined for the incidence of dicentric and acentric chromosome aberrations. The results are compared with a review of data published elsewhere. Background levels show inter-laboratory variation and possible reasons for this are discussed. By combining the present data with those from the literature the spontaneous incidence of dicentric aberrations is approx. 0.55 × 10^?3 and for acentrics is 3.7 × 10^?3. In occupationally exposed subjects a significantly higher incidence of aberrations was found. When allowance was made for the turnover of lymphocytes for the period over which each man had worked with radiation a linear dose-effect relationship was apparent. The incidence of dicentrics was 2.22 ± 0.94 × 10^?4 rad^?1 and for all unstable aberrations 8.24 ± 2.8 × 10^?4 rad^?1. These are in reasonable agreement with dose-response data obtained in vitro.     

Effects of sodium butyrate on X-ray and bleomycin-induced chromosome aberrations in human peripheral blood lymphocytes.

Peripheral blood lymphocytes from normal human volunteers or from Down syndrome patients were pre-treated with sodium butyrate (a compound which is known to induce structural modifications in the chromatin through hyperacetylation of nucleosomal core histones) and exposed to X-irradiation or treated with bleomycin in vitro in the G0 and/or G1 stage(s) of the cell cycle. The frequencies of chromosomal aberrations in the first mitosis after treatment were scored. The results show an enhancement in the yield of aberrations in the butyrate pre-treated groups. However, the absolute frequencies of chromosomal aberrations as well as the relative increases with butyrate pre-treatment varied between blood samples from different donors suggesting the existence of inter-individual variations. There is a parallelism between the effects of X-irradiation or of combined treatments in G0 and G1 stages and between effects observed in the X-ray and bleomycin series. The increase in the yields of chromosomal aberrations in butyrate-treated and X-irradiated lymphocytes (relative to those which received X-irradiation alone) is interpreted as a consequence of the inhibition of repair of DNA damage by butyrate.     

Plasma cholinesterase activity in patients with uterine cervical cancer during radiotherapy

The objectives of this study were to investigate: 1) the activity of pseudocholinesterase (PChE) in patients with uterine cervical cancer in different stages (uterine cervical carcinoma in stages II b and III and recurrent cervical carcinoma in stages III and IV a,b) and to compare it to the enzyme activity in patients with benign tumour of the uterus, and 2) the effects of radiotherapy on enzyme activity in those patients with uterine cervical carcinoma for which the chosen treatment was radical radiotherapy. Thirty patients with uterine cervical carcinoma in stages II b and III (Group A), sixteen patients with recurrent cervical carcinoma in stages III and IV a,b (Group B) and thirty-eight patients with benign tumours of the uterus (control, Group C) were evaluated and their PChE activity was determined prior to any treatment (pre-therapy enzyme activity). All eighty-four patients were free of any liver disease. The results have shown that the patients of Group A had the pre-therapy PChE activity practically identical to those in group C, but patients of Group B had significantly lower values of PChE with respect to enzyme activities of Groups A and C (p < 0.001). That is to say, PChE activity was influenced by the extent to which the malignancy had spread. Radical radiotherapy (up to 8 weeks in doses higher than 50 Gy into point A; average 80 Gy) which was the chosen treatment only for patients from group A did not cause a significant inhibition of PChE activity in any patients in comparison with their control values. With regard to the role of PChE in hydrolysis of succinylcholine, our results about the influence of the malignant disease and the radiotherapy on PChE activity are clinically significant.     

Radiation-induced micronucleus frequency in peripheral blood lymphocytes is correlated with normal tissue damage in patients with cervical carcinoma undergoing radiotherapy

In an effort to find a test to predict the response of normal tissue to radiotherapy, the lymphocyte micronucleus assay was used on blood samples from patients with cervical carcinoma. Peripheral blood samples from 55 patients with advanced-stage (II B-IV B) cervical carcinoma were obtained before radiotherapy. The patients were treated with external-beam radiotherapy followed by high-dose-rate brachytherapy. Acute and late normal tissue reactions were scored and correlated with the micronucleus frequency in lymphocytes after irradiation with 4 Gy in vitro. Great interindividual variability was observed in the radiation-induced lymphocyte micronucleus frequency, especially at 4 Gy. The mean number of micronuclei per 100 binucleated cells in cells irradiated with 4 Gy in vitro was significantly higher in samples from patients who suffered from acute and/or late normal tissue reactions than in those from patients with no reactions (51.0 +/- 17.7 and 29.6 +/- 10.1, respectively). A significant correlation was also found between the micronucleus frequency at 4 Gy and the severity of acute reactions and late reactions. However, the overlap between the micronucleus frequencies of patients with high-grade late normal tissue reactions and low-grade reactions is too great to recommend the micronucleus assay in its present form for routine clinical application.     

Frequency of chromosome aberrations in peripheral blood lymphocytes of children living in regions with various radio-ecologic situations]

First results of cytogenetic monitoring of children, living in contaminated regions of the Ukraine show statistically significant increase in quantity of chromosome aberrations, that is positively correlated with environmental situation. The effect found shows that damage of genome stability must be accounted as an indicator of increased possibility of gene-based pathology in studied groups as compared to control.     

Hexylresorcinol induces chromosome aberrations in mouse peripheral blood cells

Hexylresorcinol has been demonstrated to induce chromosome aberrations in eukaryotic cells at doses of 0.5, 0.05, and 0.005 mg/g body weight. The metabolic transformation of hexylresorcinol in mice decreases its genotoxic effect. The mutagenic effect is retained for three days only after the administration of the highest dose of hexylresorcinol (0.5 mg/g); during the first two days, lower doses are also genotoxic. Therefore, hexylresorcinol doses lower than 0.5 mg/g body weight are metabolized within two days to the extent precluding the expression of the cytotoxic effect. After a single administration to mice, exogenous hexylresorcinol is transformed at a rate of 0.0025-0.025 mg/day.     

Induction of chromosome aberrations and micronuclei in human peripheral blood lymphocytes at low dose of radiation

The chromosome damage induced by the doses of y-irradiation 6)Co in peripheral blood lymphocytes was studied using different cytogenetic assays. Isolated lymphocytes were exposed to 0.01-1.0 Gy, stimulated by PHA, and analysed for chromosome aberrations at 48 h postirradiation by metaphase method, at 49 h--by the anaphase method, at 58 h by micronucleus assay with cytochalasin B and, additionally, micronuclei were counted at 48 h on the slides prepared for the metaphase analysis without cytochalasin B. Despite of the quantitative differences in the amount of chromosome damage revealed by different methods all of them demonstrated complex nonlinear dose dependence of the frequency of aberrant cells and aberrations. At the dose range from 0.01 Gy to 0.05-0.07 Gy the cells had the highest radiosensitivity mainly due to chromatid-type aberration induction. With dose increasing the frequency of the aberrant cells and aberrations decreased significantly (in some cases to the control level). At the doses up to 0.5-0.7 Gy the dose-effect curves have become linear with the decreased slope compare to initial one (by factor of 5 to 10 for different criteria) reflecting the higher radioresistance of cells. These data confirm the idea that the direct linear extrapolation of high dose effect to low dose range--the procedure routinelly used to estimate genetic risk of low dose irradiation--cannot be effective and may lead to underestimation of chromosome damage produced by low radiation doses. Preferences and disadvantages of used cytogenetic assays and possible mechanisms of low ionising radiation doses action were discussed.     

Lysosomal enzymes in peripheral blood lymphocytes of patients with gastric cancer

The activity of acid phosphatase, beta-glucuronidase and N-acetyl-beta-glucosaminidase was assessed using semiquantitative cytochemical methods in peripheral blood lymphocytes of 45 untreated patients with gastric cancer and 80 healthy subjects. In cancer patients the study demonstrated a statistically significant decrease in the number of lymphocytes with granular reaction for acid phosphatase and N-acetyl-beta-glucosaminidase, as well as an increase in the number of lymphocytes showing a granular-diffuse reaction for the above enzymes and a diffuse reaction for all the studied lysosomal enzymes. Possible mechanisms of the observed changes are discussed.     

The characterization and transmissibility of chromosome aberrations induced in peripheral blood lymphocytes by in vitro alpha-particle radiation

Peripheral blood lymphocytes were irradiated in vitro with (213)Bi alpha particles at doses of 0, 10, 20, 50, 100, 200 and 500 mGy. Chromosome analysis was performed on 47-h cultures using single-color fluorescence in situ hybridization (FISH) to paint chromosomes 1, 3 and 5. The whole genome was analyzed for unstable aberrations to derive aberration frequencies and determine cell stability. The dose response for dicentrics was 33.60 +/- 0.47 x 10(-2) per Gy. A more detailed analysis revealed that the majority of aberrations scored as dicentrics were part of complex/multiple aberrations, with the proportion of cells containing complexes increasing with dose. Cells containing aberrations involving painted chromosomes (FISH aberrations) were further classified according to cell stability and complexity. The majority of cells with FISH aberrations were unstable. The proportion of aberrant FISH cells with complex/multiple aberrations ranged from 56% at 10 mGy to 89% at 500 mGy. A linear dose response for genomic frequencies of translocations in stable cells fitted the data from 0 to 200 mGy with a dose response of 7.90 +/- 0.98 x 10(-2) per Gy, thus indicating that they are likely to be observed in peripheral blood lymphocytes from individuals with past or chronic exposure to high-LET radiation. Comparisons with the dose response for low-LET radiation suggest an RBE of 13.6 for dicentrics in all cells and 3.2 for translocations in stable cells. Since stochastic effects of radiation are attributable to genetic changes in viable cells, translocations in stable cells may be a better measure when considering the comparative risks of different qualities of radiation.     

FISH detection of spontaneous level of chromosome aberrations in peripheral blood lymphocytes in persons of different ages

FISH-WCP method with fluorescent probes to chromosomes 1, 2, 4 was used for cytogenetical examination of two groups of male (middle age 23 and 53.5 years) who deny their deliberate contact with known or supposed mutagens. The wide inter-individual variability of the stable chromosome aberration frequencies in each group has been shown (0.006-0.014 and 0.006-0.025 per cell per genome-equivalent correspondingly). The trend of increasing of the mean-group level of one-way and two-way translocations during aging has been revealed (0.009 and 0.013 per cell per genome-equivalent, correspondingly).     

Chromosome aberrations and sister-chromatid exchanges (SCEs) in peripheral blood lymphocytes of patients suffering from poliomyelitis

The frequencies of sister-chromatid exchanges (SCEs) and various chromosome aberrations were studied in blood lymphocyte cultures of individuals suffering from polio virus infection. The frequency of SCEs was found to be within the normal range in polio patients whereas the frequency of chromatid breaks, gaps and other chromosome aberrations showed a significant (p less than 0.001) increase when compared with that of controls. It indicates that the mechanism(s) responsible for polio virus-induced chromosomal damage may not be related to or affect the molecular process(es) that functions in SCE formation.     

The chromosome aberrations in human peripheral blood lymphocytes 43-46 years after the acute radiation disease

Cytogenetic study of workers, who had an acute radiation syndrome of the medium (ARS II), severe (ARS III) and extremely severe (ARS III-IV) degrees in 1953-1957, was performed. Lymphocytes from peripheral blood were cultured and analyzed with using the routine chromosome staining (4 individuals) and FISH (2 individuals) methods. In each case 4000-1000 metaphase slides were analyzed with the group chromosome kariotyping. A high frequency of chromosome aberrations (CA) was revealed, i.e.: 9.33-9.8 CA per 100 cells for ARS II patients, 28.6 and 36.6 CA per 100 cells for patients with the severe ARS. The main type of rearrangement is stable CA (up to 90%). The CA frequency exceeds the level of spontaneous CA (control--20 individuals) and CA of the patients, who had Chronic Radiation Disease (CrRD) 45 years ago (20 individuals). By 43-46 years of the control. No cancer diseases or hematopoietic pathology were revealed by 43-46 years of follow-up.     

Dose-response relationships for chromosome aberrations in peripheral blood lymphocytes after whole- and partial-body irradiations: II. Decline of aberration-carrying cells in blood with time post-exposure

Dicentric yield and fractionation of damaged metaphases and lymphocyte count were followed for an interval of up to 3 months in rabbits after partial- and whole-body irradiations.Some partial-body exposures led to less-pronounced decline of the lymphocyte count in peripheral blood than others; in the former case the reduction of dicentric yield in peripheral blood lymphocytes over the first 24 h post exposure was significantly faster than in the latter. The decline was also faster than after uniform whole-body irradiation where it was virtually absent. However, the results suggest that, after whole-body exposures, the decline of the fraction of damaged metaphases with post-exposure time was much slower than that of the dicentric yield.     

Activity of beta-glucuronidase in peripheral blood lymphocytes of patients with cancer of the larynx.

In 20 untreated male patients with cancer of the larynx, aged 35 to 55 years, the significant increase in the absolute count of beta-glucuronidase-positive lymphocytes in the peripheral blood was examined by means of the cytochemical method of Hayashi et al. (1964). The increase was due to an elevated absolute count of lymphocytes exhibiting the granular-diffuse and the diffuse enzymatic reaction; no significant changes were observed with regard to lymphocytes with the granular type of reaction. The authors discuss the significance of their observations for the evaluation of lymphocyte immune response against tumour specific antigens in patients with cancer of the larynx.     

Time-effect relationship of chromosome aberrations in peripheral lymphocytes after radiation therapy for seminoma

The time-effect relationship of dicentrics and cells containing unstable chromosome abnormalities (Cu cells) was studied in peripheral lymphocytes of 40 blood samples from 23 patients suffering from seminoma during a time period of 0-1720 days after radiation therapy. Nine patients were studied before treatment. Since the half-time for the disappearance of damaged cells from circulating blood is an increasing function of post-exposure time it can only be expressed as a differential value. The present model discriminates between the mean lifetime m for lymphocytes and a parameter q which is the differential half-time for the decline of damaged cells immediately after exposure (t = 0). If the time t is short compared with m the decline is asymptotically time-hyperbolic rather than exponential and can be described by q only. According to recalculations of previous data, comprising 30 years post exposure, m approximates 10 years. Differential half-times can be derived for any time post treatment within the analysed time period for the decline of the incidence of dicentrics. For example at the end of therapy (t = 0) the differential half-time was calculated to be 0.4 years and at 1720 days post exposure 3.6 years resulted. The corresponding values for the percentage of Cu cells cannot be derived for t = 0; at 1720 days 3.9 years resulted.