Meiotic stage-dependent induction of chromosome aberrations in Chinese hamster primary oocytes exposed to topoisomerase II inhibitor etoposide

To investigate the chromosomal effects of topoisomerase II (topo-II)-interactive drugs on mammalian primary oocytes, female Chinese hamsters were treated with etoposide (VP-16) at various intervals pre- and post-human chorionic gonadotropin (hCG) injections. Chromosome analysis of oocytes at metaphase II (M II) showed that treatment with VP-16 at 50h pre-hCG had no effect, but the treatments between 24h pre-hCG and 2h post-hCG often caused structural chromosome aberrations. Although treatment at 4h post-hCG had no effect, subsequent treatments at 6 and 8h post-hCG produced a significant increase in structural chromosome aberrations. No effect was found following treatment at 10h post-hCG. The incidence of aneuploidy following exposure to VP-16 was also dependent on the time of hCG injection. Taking the time course of meiotic progression in primary oocytes following hCG injection and pharmacokinetics of VP-16 into consideration, it is likely that meiotic stages from late dictyate to diakinesis are highly sensitive to VP-16, while stages at dictyate and from metaphase I (M I) to telophase I (telo I) are relatively insensitive to the drug. Moreover, the effect of VP-16 on structural chromosome aberrations and aneuploidy was dose-dependent.Chromosome analysis at M I detected a frequent occurrence of structural chromosome aberrations in treated oocytes. This suggests that structural aberrations may be caused by disruption of cleavable complexes during chromosome condensation. Detection of chromosome bridges during anaphase I/telophase I (ana I/telo I) may support the hypothesis that induction of aneuploidy by VP-16 is due to failure in decatenation of recombinant homologous chromosomes.     

Biological indication and dosimetry of unstable chromosome aberration frequencies in human lymphocytes

Review is devoted to the problems of biological (cytogenetic) dosimetry and indication of degree of radiation lesions based on analysis of unstable chromosome aberrations in lymphocytes of human peripheral blood. Effects of radiation in low doses on human chromosomes and methodology of interpretation of the character of dose cytogenetic curves are discussed. Traditional cytogenetic analysis remains the basic one for monitoring in groups of people with accidental irradiation.     

A high-resolution cytogenetic map of human chromosome 12: Localization of 195 new cosmid markers by direct R-banding fluorescence in situ hybridization

We have constructed a high-resolution cytogenetic map of human chromosome 12 with 195 newly isolated cosmids by direct R-banding flourescence in situ hybridization. The fluorescent signals of 195 clones were evenly distributed throughout chromosome 12, but sublocalized preferentially to R-positive bands. This high-resolution cytogenetic map with an average map distance of 0.73 Mb on bands can, in conjunction with a genetic linkage map, facilitate the analysis of chromosomal and molecular aberrations in genetic diseases and cancers. Moreover, the cytogenetic mapping data provide starting points for establishing contig maps with cosmid clones and yeast artificial chromosomes.     

Cytogenetic studies in leprosy patients before and after chemotherapy

Summary The frequencies of chromosome aberrations and sister chromatid exchanges (SCEs), cell proliferation kinetics and mitotic indices were studied in peripheral blood lymphocyte cultures of leprosy patients both before and after chemotherapy. The differences in the frequencies of chromosome aberrations and SCEs between controls, paucibacillary and multibacillary patients were found to be statistically highly significant (P < 0.001). The extent of cytogenetic damage seemed to depend on the severity of the disease. Lymphocytes of untreated leprosy patients showed a low mitotic index and a slow rate of cell proliferation. Following combined treatment with dapsone and rifampicin there was an increase, but to a lesser degree (P < 0.01), in the frequency of SCEs and chromosome aberrations while the drug combination of dapsone, rifampicin and clofazamine had a non-mutagenic effect on chromosomes of the patient. Furthermore, after drug treatment, the cell proliferation rate and mitotic indices in paucibacillary patients were comparable to that of controls. These results indicate the clastogenic potency of Mycobacterium leprae and the remedial effects that follow therapeutic drug treatment.     

Cryptic translocations involving chromosome 20 in polycythemia vera

A systematic cytogenetic study was performed in 49 patients with polycythemia vera (PV) in order to investigate the occurrence of subtelomeric rearrangements of chromosome 20, the most frequently rearranged chromosome in this myeloproliferative disorder. Partial deletion of the long arm of chromosome 20 was observed in two patients and two cryptic translocations, t(1;20)(p36;q13) and t(18;20)(p11;q13) in two others, all previously treated. The localization of the breakpoints of the translocated 20 chromosomes was different in the two translocations, as shown by fluorescence in situ hybridization (FISH) to metaphase chromosomes using BAC clones. Although infrequent (2/49), cryptic translocations of chromosome 20 deserve to be detected as preliminary to identification of molecular defects in PV.     

Leukemic chromosome clone. I. Risk factor in the acute lymphatic leukemia of children]

As long as the aetiology of acute lymphatic leukaemia of children is not known its therapy is based on clinical experience. Among the values of experience those factors will play a part, the evidence of which during the ALL initial stage will be a risk for successful therapy and survival rate. This results in a choice of more aggressive variants of modern therapy schemes. In a cytogenetic study made in 35 children with ALL it was tested, whether even leukaemic chromosome clones will be a risk for the course of acute leukaemia. The duration of the first remission and survival rate were considered as criteria. The evidence of a leukaemic chromosome clone could be shown to be followed by a short survival rate, irrespective of the stage of the disease where the clone had been observed first. Thus, cytostatic therapy in those ALL patients who are affected with luekaemic chromosome aberration of stem line character should be aimed at the complete annihilation of the clone, irrespective of other remission criteria. The failure of blood and bone-marrow cultures as early as during the untreated initial stage indicated a primary cellular immuno-insufficiency. This combination of cell immuno-depression with high peripheral leukocytes connts and a primary mediastinal tumour or a generalizing lymphosarcoma respectively, was the highest risk up till now for the course of the disease. Judging from the duration of the first remission and the survival rates, the consecutive schemes of therapy did not differ in their effect on leukaemia with pathological stem lines. On the basis of the present study the impression could not be excluded that up till now long term survival rates could be attributed rather to individual manners of response than to the modern therapy scheme.     

Number of chromosome aberrations induced by chemical carcinogens in the cells of patients with 2 forms of xeroderma pigmentosum

A study was made of the effects of a chemical mutagen of the "gamma-type"--methylmethansulfonate (MMS) and of mutagen of the "UV-type"--4-nitroquinolin-1-oxide (NQO) and 7-brommethylbenz(alpha)antracen (BMBA) exerted on chromosome aberration frequency in lymphocytes of patients with classical Xeroderma pigmentosum and with a so-called form II of the disease on different stages of the cell cycle. Mutagens were added to PHA stimulated lymphocyte cultures every 3 hours, simultaneously with pulse 3H-thymidine labelling, to fix the stage of the cell cycle at the moment of treatment. NQO and BMBA treatments were found to increase the frequency of chromosome aberrations in classical XP cells, whereas MMS was not found to. In the XP II cells, defective in repair of both UV and gamma damaged DNA, chromosome aberrations yield is higher than in normal cells after all the three mutagens treatment. The data obtained show the correlation between DNA repair and chromosome aberrations yield.     

Equal induction and persistence of chromosome aberrations involving chromosomes 1, 4 and 10 in thyroid cancer patients treated with radioactive iodine

A number of in vitro studies have questioned the assumption of random distribution of breaks in radiation-induced chromosome aberrations. The therapeutic application of radioactive 131I in thyroid cancer patients offers a good opportunity to study the induction and persistence of cytogenetic damage involving different chromosomes in vivo. Using whole-chromosome painting probes and triple colour painting by fluorescence in situ hybridization (FISH), we have analysed the frequency of chromosomal aberrations (CAs) involving chromosomes 1, 4 and 10 in peripheral blood lymphocytes of 10 thyroid cancer patients sampled before and 1 week, 1 year and 3.5 years after therapeutic application of radioactive iodine in a self-controlled, longitudinal study. A highly significant 3.4-fold increase in the frequency of chromosome breaks was observed 1 week after treatment with a similar representation of all chromosomes analysed. Although a significant decrease in dicentrics was observed during the first year after treatment, the frequency of chromosome aberrations remained over control levels until the last sampling time, 41-47 months post-treatment. The same behaviour, in terms of induction and persistence, was observed for all three chromosomes, confirming our previous results in vitro and rejecting the reported suggestion that chromosome 10 is radiosensitive in vivo. Our finding that the dynamics of radiation-induced CA in vivo is independent on the chromosome of choice suggests that this variable is not important in retrospective studies.     

Karyologic research on murine B-cell hybridomas

Karyotypes of 10 murine hybridomas producing monoclonal antibodies to microbal antigenes were examined using chromosome slides stained with Azur-eosine. Hybrid origin of all the cell clones was confirmed. The cultures differed from each other in modal chromosome numbers, in novel markers that were absent from cells of the parental myeloma X63.Ag8.653, in the frequency of metaphases with double minute chromosomes and in the level of cells with chromosome aberrations. The results obtained enable us to recommend a cytogenetic analysis for the identification of hybridomas. The following observations point out to a relative instability of the chromosomal apparatus of hybridomas: chromosome numbers varied significantly from cell to cell within one and the same clone; modal chromosome counts decreased in 3 of 5 hybridomas that were studied repeatedly within 1-2 months; in some hybridomas unstable chromosome aberrations were found in 18-38% of cells.     

Long-term cytogenetic effects in children prenatally-exposed to radiation as a result of the accident at the Chernobyl Atomic Energy Station

Forty-two children exposed to ionizing radiation in prenatal period and 15 children of control group were examined in the remote terms after the accident using the method of differential G-staining of chromosomes in lymphocytes of peripheral blood. It was found that the average group rate of aberrant cells and chromosome aberrations was reliably higher in the children exposed in utero compared to control. Long-term cytogenetic consequences of the pre-natal exposure were characterized by prevalence of aberrations of a chromosome type, mainly stable chromosome lesions. At chronic exposure to low doses of ionizing radiation the increase in the rate both stable and unstable chromosome aberrations.     

The chromosomal radiosensitivity of children whose parents were exposed to antitumor radiochemotherapy]

The effect of gamma radiation was studied on routine stained chromosomes from lymphocytes of children born to Hodgkin's disease patients after cancer therapy (CP) in comparison to children from healthy parents (HP). Irradiation (0, 0.25, 0.50, 1.00, 1.50 Gy) of the whole blood was performed in culture medium. Metaphases were obtained from 52-h cultures. Chromosomal aberrations were used as an endpoint. Aberrations of both chromosomal and chromatid types were scored in 150-200 metaphases for estimation of spontaneous level of cytogenetic injuries and in 100 metaphases of induced one. It is found that chromosomes of CP children are more radiosensitive than chromosomes of HP ones, the spontaneous frequency of chromosome aberrations being equal in both groups.     

A canine cancer-gene microarray for CGH analysis of tumors

As with many human cancers, canine tumors demonstrate recurrent chromosome aberrations. A detailed knowledge of such aberrations may facilitate diagnosis, prognosis and the selection of appropriate therapy. Following recent advances made in human genomics, we are developing a DNA microarray for the domestic dog, to be used in the detection and characterization of copy number changes in canine tumors. As a proof of principle, we have developed a small-scale microarray comprising 87 canine BAC clones. The array is composed of 26 clones selected from a panel of 24 canine cancer genes, representing 18 chromosomes, and an additional set of clones representing dog chromosomes 11, 13, 14 and 31. These chromosomes were shown previously to be commonly aberrant in canine multicentric malignant lymphoma. Clones representing the sex chromosomes were also included. We outline the principles of canine microarray development, and present data obtained from microarray analysis of three canine lymphoma cases previously characterized using conventional cytogenetic techniques.     

Cytogenetic effects of inhaled ozone in man

Peripheral blood samples were collected from 30 normal male volunteers before and at various intervals after inhaling 0.4 ppm ozone for 4 h. Data from 4 of the subjects were excluded from the analysis because of missing data points. The blood samples were cultured for 48 h, slides made and stained with a uniform Giemsa stain, and 100 metaphase spreads per subject per treatment scored for chromosome aberrations. Cells with suspected aberrations were photographed, destained, restained with a banding procedure and rephotographed to identify the specific chromosomes and regions involved.Pre-exposure, immediate post-exposure, 3 days post-exposure, 2 weeks post-exposure and 4 weeks post-exposure means for the percentage of cells with 46 chromosomes were 93.0, 93.6, 91.7, 94.5 and 94.2, respectively; in the same order, the mean number of cells with chromatid and/or chromosome breaks per 100 cells was 0.96, 0.85, 1.00, 0.88 and 0.81 respectively, and for chromatid and/or chromosome gaps per 100 cells: 1.35, 0.96, 1.35, 0.81 and 0.77, respectively. The means for each of these parameters as well as the mean frequencies of complex aberrations are not statistically significantly different between blood sampling times. The distribution of aberrations by chromosome and light and dark bands is not significantly influenced by ozone exposure.These data indicate no apparent detectable human cytogenetic effect due to exposure to ozone under the conditions of this experiment.     

A new cytogenetic aspect of polycythemia vera

Summary The cytogenetic findings in a group of 15 polycythemic patients are reported. G and C banding techniques were used on bone marrow and peripheral blood preparations. Major chromosomal aberrations were found in four out of the 15 patients, an incidence similar to that found in other studies on polycythemia. The most interesting finding concerned the chromosomal polymorphism of the pair 19. A possible relation to the etiology of the disease is discussed.     

Chromosome aberrations and rogue cells in lymphocytes of Chernobyl clean-up workers

A cytogenetic analysis was performed on peripheral blood lymphocytes from 183 Chernobyl clean-up workers and 27 control individuals. Increased frequencies of chromosome aberrations were associated with exposure to radiation at Chernobyl, alcohol abuse and a history of recent influenza infection. However, only approximately 20% of Chernobyl clean-up workers had an increased frequency of dicentric and ring chromosomes. At the same time, an increased frequency of acentric fragments in lymphocytes of clean-up workers was characteristic. The use of multivitamins as dietary supplement significantly decreased the frequency of chromosome aberrations, especially of chromatid breaks. Rogue cells were found in lymphocytes of 28 clean-up workers and 3 control individuals. The appearance of rogue cells was associated with a recent history of acute respiratory disease (presumably caused by adenoviral infection) and, probably, alcohol abuse. Dicentric chromosomes in rogue cells were distributed according to a negative binomial distribution. Occurrence of rogue cells due to a perturbation of cell cycle control and abnormal apoptosis is suggested.     

Decrease of incidence of chromosome aberrations after a course of hyperbaric oxygenation

The influence of the course of hyperbaric oxygenation (HBO) on the peripheral blood lymphocytes chromosomes of 7 patients with different pathology and of 3 healthy volunteers was studied. It is proved that after HBO course the frequency of chromosome, aberrations of chromatid type hasn't been practically changed whereas the frequency of aberrations of chromosome type significantly decreases by three times on the whole.     

Chromosome aberrations of clonal origin are present in astronauts' blood lymphocytes

Radiation-induced chromosome translocations remain in peripheral blood cells over many years, and can potentially be used to measure retrospective doses or prolonged low-dose rate exposures. However, several recent studies have indicated that some individuals possess clones of cells with balanced chromosome abnormalities, which can result in an overestimation of damage and, therefore, influence the accuracy of dose calculations. We carefully examined the patterns of chromosome damage found in the blood lymphocytes of twelve astronauts, and also applied statistical methods to screen for the presence of potential clones. Cells with clonal aberrations were identified in three of the twelve individuals. These clonal cells were present in samples collected both before and after space flight, and yields are higher than previously reported for healthy individuals in this age range (40-52 years of age). The frequency of clonal damage appears to be even greater in chromosomes prematurely condensed in interphase, when compared with equivalent analysis in metaphase cells. The individuals with clonal aberrations were followed-up over several months and the yields of all clones decreased during this period. Since clonal aberrations may be associated with increased risk of tumorigenesis, it is important to accurately identify cells containing clonal rearrangements for risk assessment as well as biodosimetry.     

An investigation of Ph1 chromosome in Chronic Myeloid Leukemia patients with different treatment modalities and hematological features

Chronic myeloid leukemia (CML) is characterized by a Ph¹ chromosome that derives through a translocation between chromosomes 9 and 22, i.e., t (9;22). Identifying the Ph¹ chromosome through cytogenetic analysis is an important aspect of CML diagnosis. The aim of this study was to determine the significance of cytogenetic analysis in the diagnosis of CML as well as to find out a relationship between chromosomal abnormalities and CML patients in different stages of treatment. Six CML patients were investigated for this study. The presence of Ph¹ chromosome was detected at different times of treatment using GTG banding on peripheral blood or bone marrow aspirations, and the results were analyzed using cytovision workstation. Hematological features were compared between newly diagnosed patients and patients under treatment. The Ph¹ chromosome was strongly associated with all cases of CML. The regression of Ph¹ chromosomes differed for each patient depending on the treatments and individual response to specific treatments.     

The most frequent chromosomal abnormalities in karyotypes of patients with reproductive problems

Results of cytogenetic and molecular-cytogenetic inspection of 210 matrimonial pairs with the problems of reproduction are presented. Different types of chromosomal aberrations have been detected in the karyotypes of the patients in 46 (10.95%) cases. Such structural chromosomal aberrations as pericentric inversions, Robertsonian translocations, balanced reciprocal translocations, and marker chromosomes as well prevailed the numerical chromosomal aberrations (89.13% and 10.87% cases accordingly). In the general group of the inspected patients there were 19 cases (4.52%) characterized by the low level of X and Y chromosome mosaicism. The authors suppose that the patients with the exposed chromosomal abnormalities need the differentiated approach at their treatment.     

The most frequent chromosomal abnormalities in karyotypes of patients with reproductive disorders

Cytogenetic and molecular cytogenetic characteristics have been studied in 210 couples with fertility problems. The patients’ karyotypes contained various chromosomal rearrangements in 46 cases (10.95%). The structural chromosomal rearrangements such as pericentric inversions, Robertsonian translocations, balanced reciprocal translocations, and marker chromosomes were more frequent than numerical chromosome aberrations (89.13 and 10.87% of cases, respectively). We have found 19 (4.52%) karyotypes with “hidden’ low mosaicism in X and Y chromosomes. We believe that the patients with chromosomal anomalies in the karyotype need differentiated treatment.