Aberrations In Peripheral Blood Lymphocytes Research Articles

Normal genetic response to gamma irradiation in familial adenomatous polyposis.

The present study, a co-operative project between three European institutes, was aimed at elucidating whether the APC gene in carriers of familial adenomatous polyposis coli (FAP) also causes some genetic sensitivity revealed by DNA damage and the yield of chromosome aberrations in peripheral blood lymphocytes exposed to gamma rays. In addition, it seemed of interest to study whether DNA repair is modified after irradiation of lymphocytes from FAP patients compared to controls. To this end, we have used the inhibition of the poly(ADP-ribose) polymerase (ADPRP) by 3-aminobenzamide (3ABA) and studied the effect of 3ABA on the frequency of DNA strand breaks and chromosome aberrations. The data indicate that FAP is not associated with an increased chromosomal sensitivity towards ionising radiation.

Chromosome aberrations in peripheral blood lymphocytes from control individuals

This study emphasizes the problems encountered in obtaining suitable contol levels for comparison with occupational studies of exposure to clastogens. Blood samples taken from 135 individuals (69 females and 66 males) were examined for chromosome aberrations. The data include 15 368 cells scored for chromosome aberrations. The frequencies of chromatid and chromosome breaks, acentric fragments and dicentrics were determined. The frequency of the most common chromosome aberration, chromosome breaks, was 1.1 x 10 -2 and for dicentries 0.26 x 10 3. The values obtained were investigatd in relation to sex, cigarette smoking habits, diagnostic X-ray exposure and use of antibiotics. In all the parameters, no significant differences were found.

Erkennung strahleninduzierter Chromosomenaberrationen mittels Fluoreszenz-Hybridisierung und Bildanalyse

In biological dosimetry, the dose can directly be estimated from radiation-induced chromosome aberrations in peripheral blood lymphocytes. For statistical reasons a very high number of cells has to be analyzed. A new technique called fluorescence in situ hybridization allows to delineate chromosome aberrations specifically by fluorescence labelling. In contrast to „classical” banding techniques, these labels give a pattern whose analysis can be easily automatized and accelerated. Especially, translocations can be used as a parameter which in former times were normally excluded from consideration due to the complexity of their banding characteristics. The methodological possibilities of fluorescence hybridization and microscopical analysis by means of image analysis will be reported by some examples.

Urinary cyclophosphamide excretion and chromosomal aberrations in peripheral blood lymphocytes after occupational exposure to antieoplastic agents

In this study we have compared the results of a method for the detection of cyclophosphamide in urine and the results of analysis of chromosomal aberrations in peripheral blood lymphocytes of ofur groups of subjects with various exposure statuses. These groups are 17 Dutch and 11 Czech exposed workers (maily hospital nurses and pharmacy technicians) handling antineoplastic agents and 35 Dutch and 23 Czech controls (nurses, medical doctors, pharmacy and lab technicians) not handling these drugs. The groups were subdivided into smokers and non-smokers because of a confounding effect of smoking. Within the Dutch groups, the percentage of aberrant cells and the number of breaks per cell were increased for smokers compared to non-smokers. The percentage of aberrant cells was increased in Dutch exposed workers in comparison with Dutch control workers. Within the Czech groups the percentage of aberrant cells and the number of break per cell were increased in exposed wotkers in comparison with control workers. However, both Dutch and Czech smokers mainly contributed to the increase. The results suggest an additive effect of exposure and smoking in the Dutch subjects and a more than additive effect in the Czech subjects. In urine samples of three out of 11 Dutch exposed workers cyclophosphamide was found in a range of 0.1−0.5 μ g 24 h . Higher levels were detected in the urine of eight out of 11 Czech exposed workers, a range of 0.1−2.9 μ g 24 h . No correlation was observed between the amounts of cyclophosphamide excreted in urine on the one hand and the percentage of aberrat cells and the number of breaks per cell on the other hand. The present study is the first study showing that hospital workers having an increase in chromosome aberrations related to their work are exposed to at least antinoeplastic agent.

Increases in chromosome aberrations and in abnormal sperm morphology in rubber factory workers

Subjects working at a rubber plant in a chemicals warehouse or in calandering and bambury units were analyzed for both sperm parameters and structural chromosome aberrations in peripheral blood lymphocytes. Sperm analysis war performed in a group of 24 workers for comparison with fertile (n = 24) and infertile (n = 24) control groups. The statistical analyses of semen volume, vitality and sperm count did not show significant differences between exposed and fertile groups but significant differences were found from the infertile group. A significantly lower proportion of normal sperm head shapes was found in exposed subjects when compared to the fertile group (40.1 vs. 57.8). Seven exposed workers were re-analyzed 1 year and their sperm parameters did not change. The cytogenetic analysis showed a significant increase (3.90%) in the percentage of cells with aberrations in bambury workers (n = 11). However, no differences were found between calandering workers (n = 8) and control subjects (n = 10). Workplace air samples taken on the day of tissue sampling did not show any increase above the Cuban maximal allowed concentration for benzo[ a]pyrene or toluene.

Health status of children whose grandparents had been subjected to occupational external gamma-exposure

This paper presents the results of long-term studies conducted into the health state of grandchildren of individuals occupationally exposed to chronic irradiation before conception. Differences between the study group and the control group were neither found in the physical development (i.e. morbidity as well as structure and frequency of congenital maldevelopment), nor in the frequency of chromosomal aberrations in peripheral blood lymphocytes. Multifactorial analyses revealed no radiological influence on the occurrence of health disorders in grandchildren of irradiated grandparents. Correlations with non-radiological factors (medical, biological, social) were found, however, for a number of disorders in the cohort of children under study: hypotrophy, allergic diathesis, morbidity rates, congenital malformations.

Monitoring of benzene-exposed workers for genotoxic effects of benzene: improved-working-condition-related decrease in the frequencies of chromosomal aberrations in peripheral blood lymphocytes

The genotoxic effects of benzene were assessed in peripheral blood lymphocytes of 49 workers occupationally exposed to benzene (3–68.7 mg/m 3 in the work environment) for 0–2, 2–10 and more than 10 years (10, 22 and 17 workers, respectively). Chromosomal aberrations, SCEs and UV-induced DNA synthesis were used as indicators of genotoxic effects. Most of the workers were followed up in 1991 and 1992, while the benzene concentrations were reduced to 1–18.4 mg/m 3 air. Considered overall, in the “exposed” groups, the frequencies of chromosomal aberrations were significantly higher than in controls thus providing evidence for the clastogenic effects of benzene. However, there seems to be no correlation between aberration frequencies and the duration of prior exposure to benzene. In 1991 and 1992 when the benzene concentrations were brought down, there was a concomitant decrease in the frequencies of chromosomal aberrations; in 1992 the decrease reached one third to one half of the initial frequencies, values still higher than in the controls. With the other genotoxic end-points, the changes were small and not consistent.

A family showing no evidence of linkage between the ataxia telangiectasia gene and chromosome 11q22-23.

We have studied an inbred family in which two cousins presented with the same clinical features of ataxia telangiectasia (AT). Both patients are still ambulatory at ages 25 and 20. Cellular features of both patients are typical of AT and include increased radiosensitivity and an increased level of spontaneously occurring chromosome aberrations in peripheral blood lymphocytes. Linkage studies and haplotype analysis show no clear evidence that the gene for AT in this family is on chromosome 11q22-23. As previously reported AT families from complementation groups AB, C, and D have all shown linkage to this region of 11q22-23. Our study is of importance in suggesting additional locus heterogeneity.

Peripheral blood chromosome aberrations in MDS

The frequency of non-clonal structural and numerical chromosome aberrations in peripheral blood lymphocytes of 51 patients with MDS and 37 age-matched hematologically normal subjects is assessed. The frequency of aneuploid cells (p < 0.001) and of structural aberrations (p < 0.005) was significantly higher in MDS patients than in normal subjects, but showed no relationship with FAB type or with the presence of clonal karyotype abnormalities in the bone marrow. Exchange configurations were only observed in MDS patients (27.5%). The data also suggest that there may be an association between high peripheral blood aberration levels and rapidly progressive disease. This may indicate increased mutagen sensitivity and have implications for treatment.

Effect of neonatal exposure to 5-bromo-2'-deoxyuridine on life span, estrus function and tumor development in rats--an argument in favor of the mutation theory of aging?

Outbred LIO rats were exposed to subcutaneous injections (3.2 mg) of a synthetic analogue of thymidine, 5-bromo-2'-deoxyuridine (BrdUrd), on days 1 and 3, or days 1, 3, 7 and 21 of postnatal life. The mean life span decreased by 31% and 38% in male and by 14% and 27% in female rats that received 2 and 4 injections of BrdUrd, respectively, in comparison to untreated controls. The opening of the vagina was delayed, whereas age-related changes in the length of the estrous cycle and in the incidence of persistent estrus and/or anestrus were observed earlier in BrdUrd-injected female rats than in untreated ones. Inhibition of compensatory ovarian hypertrophy induced by hemiovariectomy at the age of 3 months was found in females exposed neonatally to BrdUrd as compared to untreated rats, while the uterus weight increase induced by the administration of human chorionic gonadotropin was similar in both control and BrdUrd-treated infantile rats. These data suggest that exposure to BrdUrd in early life impairs pituitary gonadotropic function in female rats. It was also shown that neonatal administration of BrdUrd to rats doubles the incidence of chromosome aberrations in peripheral blood lymphocytes in comparison to controls and is followed by a dose-related increase in tumor incidence. Our observations on the decrease in mean and maximum life span, acceleration of age-related changes in reproductive system function, increase in chromosome aberration and tumor incidence and decrease in tumor latency in rats exposed to BrdUrd in early life suggest that this model could be used as a model of accelerated aging and that some of the results can be interpreted as arguments in favor of the mutation theory of aging.

Cytogenetic surveillance of tobacco-areca nut (mava) chewers, including patients with oral cancers and premalignant conditions

Three cytogenetic endpoints were studied in non-chewing healthy controls and 3 groups of tobacco-areca nut chewers, viz. normal chewers, chewers with oral submucous fibrosis and chewers with oral cancer. Frequencies of sister-chromatid exchanges and chromosome aberrations in peripheral blood lymphocytes and of micronucleated cells in exfoliated buccal mucosa were evaluated. All the parameters showed statistically significant elevations in all 3 groups of chewers compared to the controls. The data indicate possible application of the parameters as sensitive endpoints for monitoring tobacco-areca nut chewers, the group of individuals at higher risk of developing oral cancer, the commonest cancer among Indian males.

The effect on lymphocyte chromosomes of additional radiation burden due to fallout in Salzburg (Austria) from the Chernobyl accident

An investigation has been carried out to determine whether chromosome aberrations in peripheral blood lymphocytes reflect the elevated environmental dose of low-LET ionising radiation, mainly due to radiocesium from Chernobyl fallout, to the population living in Salzburg city. Sixteen volunteers were sampled 1 year after the Chernobyl accident. Two of these persons were also sampled before the accident, and then in 1988 and 1990. The radioactive environment of Salzburg city and the radiation burden of its inhabitants have been frequently determined before and after the accident. The Cs-137 content of the volunteers was measured by whole-body counting. The additional external plus internal radiation doses in the year 1987 to the tested individuals ranged between 15 and 68% of the former normal environmental burden. The aberration frequencies showed a sharp increase of about a factor 6 from the pre-Chernobyl dose rate (0.9. mGy/year) to the post-Chernobyl dose rate (about 2 mGy/year total) but then decreased again with higher additional dose. In the two persons analysed before and up to 4 years after the accident the aberration yield showed a significant increase from 1984/85 to 1987, a decrease in 1988 and a further decrease in 1990. If these last 2 values are plotted against additional dose they fit the curve of the pooled 1987 values. The dose-effect curves revealed the same tendency as we found in various previous investigations and support the assumption that repair enzymes could be triggered by a certain amount of damage to the DNA.

Genotoxic effects of radiotherapy and chemotherapy on the circulating lymphocytes of breast cancer patients. I. Chromosome aberrations induced in vivo

Unstable chromosome aberrations were scored in peripheral blood lymphocytes (PBL) serially collected from 21 breast cancer patients before and after radiotherapy (RT), chemotherapy (CT) and combined treatments. Local radiotherapy as treatment for mammary cancer induced unstable chromosome aberrations in peripheral blood lymphocytes. Only a fraction of these lymphocytes were exposed to irradiation during treatment and the chromosomal damage observed in PBL was equivalent to that induced by irradiation in vitro with 2 Gy at high dose rate, i.e., about 4% of the total dose delivered locally. Chemotherapy alone did not induce such anomalies. Apart from the observed interindividual variations in either the level or the fate of dicentrics with time, different features of chromosome damage were found when chemotherapy was given before or after local cobaltotherapy: secondary chemotherapy did not alter the frequency and the overdispersed distribution of dicentrics observed after first-line radiotherapy; in contrast, when CT was given before radiotherapy, a lower dicentric frequency was scored, the distribution of dicentrics was not always found to be overdispersed and there was a time-dependent decrease in dicentrics after in vivo exposure.

Comparison of three assays for genetic effects of antineoplastic drugs on cancer patients and their nurses

Three assays have been compared for their ability to detect genetic damage caused by antineoplastic drugs in cancer patients and possible damage in the nurses who administered these drugs. The assays were sister chromatid exchanges (SCE) and chromosomal aberrations in peripheral blood lymphocytes, and the Salmonella/mammalian microsome assay on urine. Three comparisons were made: 1) patients before versus after treatment; 2) the administering nurses immediately after their work period versus after a few days off that followed (work and off-work); 3) the exposed nurses versus other nurses who did not administer antineoplastic drugs (controls). The SCE assay detected the treatments in all eight patients from whom complete data were obtained, and was positive in two nurses with a long history of smoking. The Salmonella/mammalian microsome assay detected eight of ten treatments in patients but failed to detect smokers. Four of nine patients receiving treatment were detected by the analysis of chromosomal aberrations. The SCE assay did not distinguish between the work and off-work samples in either the exposed or control nurses. The exposed nurses, as a group, had slightly fewer SCEs than the controls due to the two smokers detected in the latter group. Chromosomal aberration was the only assay which showed significant difference between the two samples of the exposed nurses and, consequently, between the exposed and control nurses. These differences, however, arose primarily from a higher frequency of aberrations found among the exposed nurses in samples taken after a few days away from work, rather than at the end of their work period. There is no evidence that the increase was connected to occupational exposure.

Effect of heterogeneity of human population in cell radiosensitivity on the extrapolation of dose-response relationships to low doses.

Presented are the results of an investigation of the dose-response relationship for the yield of chromosome aberrations in peripheral blood lymphocytes of persons with some hereditary diseases which represent the high risk group with respect to the increased incidence of malignant tumors and decreased life span. Despite substantially different absolute radiosensitivities of chromosomes, the variations of the alpha/beta ratio determining the extrapolation of experimental dose-response relationships to low doses did not prove to be too high, the mean deviation from the control being 15%. This points to the possible practical use of the dose-response relationships averaged over the human population as a whole.

Cytogenetic monitoring of industrial populations potentially exposed to genotoxic chemicals and of control populations

Currently the most applied technique for monitoring biological effects of exposure to genotoxic chemicals in industrial workers is the measurement of chromosome aberrations in peripheral blood lymphocytes. In the Shell petrochemical complex in The Netherlands cytogenetic monitoring studies have been carried out from 1976 till 1981 inclusive, in workers potentially exposed to a variety of genotoxic chemicals, i.e. vinyl chloride, ethylene oxide, benzene, epichlorohydrin, epoxy resins. Average exposure levels to these chemicals were well below the occupational exposure limits. Results of these studies indicate that no biologically significant increase in the frequencies of chromosome aberrations in the exposed populations occurred compared with control populations. Our experience with this methodology has shown that the results of chromosome analyses are difficult to interpret, due to the variable and high background levels of chromosome aberrations in control populations and in individuals. It is concluded that the method is not sufficiently sensitive for routine monitoring of cytogenetic effects in workers exposed to the low levels of genotoxic compounds.

Chromosome aberration frequency and radiation dose to lymphocytes by alpha-particles from internal deposit of Thorotrast.

Frequencies of chromosome aberrations in peripheral blood lymphocytes from 63 Thorotrast patients were analysed basing on the age distribution of lymphocytes. The frequency and distribution of chromosome aberrations among lymphocytes are best explained if we assume that the lymphocytes are renewed as an exponential function of time and spend most of their lifetime in the distributive pool where, while exchange of lymphocytes is taking place, the lymphocytes are hit by alpha-particles from Thorotrast aggregates resulting in the formation of chromosome aberrations and killing at specific rates per hit. The model predicts that the aberration frequency is rather insensitive to the fluence rate because of modulation by cell killing by hit. Fitting the observed data to the model showed that approximately 0.8 dicentrics and rings were produced by a single path of alpha-particle and average fluence rate to lymphocytes in a group of patients with the highest aberration frequency was estimated to be about 1.5 hits or 87 rad/lymphocyte/year.

Higher incidence of spontaneous sister-chromatid exchanges (SCEs) and X-ray-induced chromosome aberrations in peripheral blood lymphocytes during pregnancy

Communicated by F.H. Sobels In vitro cultures of peripheral blood lymphocytes from human and muntjac (barking deer) females who were at an advanced stage of pregnancy (32–37 weeks pregnant women and 20–24 weeks pregnant muntjacs) showed an enhanced frequency of SCEs and X-ray-induced chromosome aberrations when compared with those of nonpregnant females. Lymphocyte cultures of nonpregnant females to which sex hormones progesterone, oestrogen and human chorionic gonadotropin (HCG) were added together exogenously also showed higher frequency of SCEs. The plausible reason(s) for such high incidence of SCEs during pregnancy is discussed.

Cytogenetic examination of leucocytes of workers exposed to mercury vapour.

Cytogenetic observations have been performed on male subjects occupationally exposed to elemental mercury in a plant where mercury is amalgamated with zinc and in a chloralkali plant [n = 22; average level of mercury in urine was 117 micrograms/g creatinine and of mercury in blood 3.1 micrograms/100 ml; mean duration of Hg exposure 4 years (range: 0.3-15.3)]. The exposure to mercury vapour did not result in an increased yield of structural chromosomal aberrations in peripheral blood lymphocytes of the workers. These negative results are in agreement with the findings reported for other eukaryotic systems and confirm that population monitoring based on cytogenetic examination of peripheral blood lymphocytes does not always represent a good indicator of damage to genetic material produced by a chemical.

Effect of occupational exposure to epichlorohydrin on the frequency of chromosome aberrations in peripheral lymphocytes

The relationship between the level of occupational exposure to epichlorohydrin (ECHH) and the clastogenic effect was studied on a group of 33 workers. The effect of ECHH was assessed by differences in the frequency of chromosome aberrations in peripheral blood lymphocytes in ECHH-exposed and control groups. In the group exposed to the average ECHH concentration, 0.384 mg ·m −3, during the last 6 months, the cytogenetic analysis revealed 2.00 ± 0.23% AC (aberrant cells) (0.0203 B/C, breaks per cell) as compared with 1.68±0.23% AC (0.0172 B/C) in the matching controls. These results indicate that an average concentration lower than 0.40 mg·m −3 ECHH in the working atmosphere has no significant clastogenic effect on human peripheral lymphocytes.