Sister chromatid exchanges in patients with carcinoma in situ of cervix uteri.

Sister chromatid exchange (SCE) was analyzed in lymphocytes of 21 patients with carcinoma in situ of cervix uteri and 19 control subjects. The mean SCE frequencies were 8.92 +/- 0.31 (n = 417) and 6.94 +/- 0.23, (n = 375) per metaphase in patients and controls, respectively. The increase of SCE levels in cancer patients was highly significant in respect to controls (p less than 0.001). Together with data of other authors in patients with precancerous and cancerous lesions of the cervix, our results suggest that there is no correlation between SCE rate and severity of cancerous lesions.     

Sister chromatid exchange and chromosome abnormalities in uremic patients

Chronic renal failure heightens the risk of malignancy. We therefore examined lymphocytes from 44 uremic patients and 24 normal controls for chromosome abnormalities and sister chromatid exchange (SCE) rate. This is the first report of SCE in uremia. Uremia was found to increase structurally abnormal chromosomes and elevate the rate of SCE. These cytogenetic changes in uremia may play a role in the heightened risk of cancer.     

Sister chromatid exchanges in peripheral lymphocytes from women with carcinoma of the uterine cervix

Sister chromatid exchanges (SCE) are reciprocal exchanges between sister chromatids. It has been reported that in patients with cervical cancer, the frequency of SCE in peripheral lymphocytes is significantly higher than that in normal individuals; however, other studies have shown no significant difference. The aim of this unmatched case-control study was to compare the mean number of SCE per metaphase in lymphocytes from women with and without carcinoma of the cervix uteri. The SCE specimens were prepared by the fluorescence plus giemsa technique in peripheral lymphocytes from 28 women with carcinoma of cervix uteri and 28 controls. The mean number of SCE per metaphase in women with carcinoma of cervix uteri (7.80 +/- 1.05) was higher than the control group (6.98 +/- 1.13) (P < 0.05; t-test). This study had a statistical power of 0.80 and an alpha value of 0.05. This finding suggests that an increased number of SCE in peripheral lymphocytes is associated with cervical cancer. We consider that the lack of reported association of SCE and cervical cancer might be attributed to the none determination of the statistical power and sample size.     

Sister chromatid exchange in aplastic anemia

The incidence of sister chromatid exchanges (SCE) in the lymphocytes of patients with aplastic anemia (AA) was determined before and after exposure to mitomycin C (MMC). The “baseline” SCE rate was significantly higher in AA, but MMC-induced SCE rate was not different compared to controls. It is suggested that some patients with AA may have an underlying DNA damage.     

Sister chromatid exchange in dyskeratosis congenita lymphocytes.

Sister chromatid exchange (SCE) frequency in chromosomes from lymphocytes of a patient with dyskeratosis congenita was 12-2 per mitosis. Our 33 normal controls had a mean of 5-4 SCE per mitosis and 5 patients with Fanconi's anaemia averaged 7-6 SCE per mitosis. The rate of chromosome breakage was only 0-5% in the dyskeratosis congenita patient and 0 to 2-5% in controls, while the Fanconi's anaemia patients showed higher values.     

Malignant melanoma: sister chromatid exchange analysis in three families

Sister chromatid exchange (SCE) was analyzed in stimulated lymphocytes and skin fibroblasts in members of three families with cutaneous malignant melanoma (CMM). Two of these families were characterized by familial CMM; the other family had one patient affected by CMM and two others with other cutaneous melanocytic lesions. All the patients had undergone surgery but no chemotherapy. Higher and differing SCE rates were found in lymphocytes and in fibroblasts of all patients. A wide range of SCE distribution was found in patients with high SCE rate. A few healthy close relatives also showed relatively high SCE rates and wide range distributions. These subjects may be regarded as a subset of family members at high risk for developing cancer. The variability of SCE rates and distribution may reflect genetic heterogeneity of CMM.     

Spontaneous chromosomal instability in breast cancer families

Spontaneous chromosomal instability has been correlated with cancer predisposition. In the present study, the phenomenon has been evaluated using two cytogenetic markers, namely, frequency of spontaneous sister chromatid exchanges (SCE) and spontaneous chromosomal aberrations (CA) in peripheral blood lymphocytes of hereditary breast cancer (HBC) patients (n = 11) and healthy blood relatives (HBR, n = 36). A statistically significant difference was observed for both the endpoints between HBC patients and controls (P < 0.001), HBC patients and HBR (P < 0.001), as well as HBR and controls (P < 0.001). Thus, 63.64% of the HBC patients and 25% of HBR showed a mean CA/cell value higher than the highest mean CA/cell value of the controls (0.11 CA/cell). Similarly, 81.81% of the HBC patients and 61.11% of HBR showed a mean SCE/cell value higher than the highest mean SCE/cell value of the controls (9.60 SCE/cell). Chromosomal aberrations were more frequently observed in the B and E group of chromosomes in HBC patients and HBR. These findings primarily indicate the high level of chromosomal instability in breast cancer families, and might be one of the predisposing factors for high risk of cancer in HBR.     

SCE and UDS studies in a family with retinoblastoma: a case study

The frequencies of both spontaneous and mitomycin C (MMC)-induced sister chromatid exchanges (SCE) were analyzed in mixed lymphocyte cultures from a kindred with retinoblastoma. Both the affected daughter and male proband, as well as two normal controls, were studied. No differences were observed in the spontaneous or in the MMC-induced SCE frequencies obtained from the peripheral lymphocytes of these patients compared to the normal controls. Unscheduled DNA synthesis (UDS) was observed in the lymphocytes treated with varying concentrations of both MMC and M-methyl-N-nitro-N-nitrosoguanidine (MNNG). Whereas no differences were observed in the rate of [3H]thymidine incorporation in the retinoblastoma-derived lymphocytes exposed to MMC when compared to the controls, differences were seen in the response to MNNG. Our data suggest that cells from these retinoblastoma patients respond like normal cells to damage induced by MMC, but that they are unable to repair damage induced by MNNG.     

Chromosome breaks and sister chromatid exchanges in albinos in Nigeria

The prevalence of squamous cell carcinoma of the skin in albinos reaches approximately 90 % in patients over 20 years of age in the vicinity of Enugu, Nigeria. Chromosome breaks and sister chromatid exchanges (SCE) were evaluated in tyrosinase-positive oculocutaneous albinos and pigmented controls of Ibo extraction who were life-long residents of Nigeria. No difference in the frequency of chromosomal breaks in 14 albinos compared to 6 pigmented controls, and no differences in the frequency of SCE in 9 albinos compared to 3 controls could be detected. Increased chromosomal abnormalities in lymphocytes do not appear to be associated with albinism or fulminating skin cancer present in albinos in the tropics.     

Sister chromatid exchanges in leukemic patients

Sister chromatid exchange (SCE) was studied in PHA-stimulated peripheral blood lymphocytes from 36 newly diagnosed and untreated leukemic patients: 16 with acute lymphoblastic leukemia (ALL), 10 with acute nonlymphocytic leukemia (ANLL), and 10 with chronic myelocytic leukemia (CML). The metaphases analyzed show no chromosomal abnormalities. The mean SCE frequency (mean +/- SE) for each group of patients was: 6.8 +/- 0.4, 6.6 +/- 0.3, and 7.0 +/- 0.6 per mitosis, respectively, which was significantly lower than the mean SCE score for 30 controls (8.7 +/- 0.2). No differences in SCE score among ALL, ANLL, and CML and a similar SCE frequency by chromosome number and group allowed consolidation of all the cases into a single group of 36 leukemic patients (6.8 +/- 0.3). When the frequency of SCE was compared by chromosome number and group between the leukemic patients with the control group, a significant decrease in SCE frequency was observed due to a low SCE score in almost all the complements, except chromosome #1. It is suggested that the low SCE rate is related to the leukemic process itself.     

Sister chromatid exchange in malignant lymphomas

Sister chromatid exchange (SCE) was evaluated in peripheral lymphocytes from 20 untreated patients with malignant lymphomas: 6 with Hodgkin's disease (HD), 14 with non-Hodgkin lymphoma (NHL), and 5 with lymphadenitis. The mean SCE frequency (+/- SE) was: 11.2 +/- 0.6, 11.0 +/- 0.6, and 7.2 +/- 0.3 for HD, NHL, and lymphadenitis patients, respectively, and 8.7 +/- 0.2 for the control group. No differences in SCE score were observed in HD and NHL. These results allowed us to consider both groups (HD and NHL) as a single neoplastic population (mean +/- SE, 11.0 +/- 0.4). No significant differences were found between the lymphadenitis and control groups. On the other hand, significantly higher SCE scores were seen in neoplastic populations than in the control and lymphadenitis groups (p less than 0.001 and p less than 0.01, respectively). When SCE was compared by chromosome number and group between neoplastic patients and controls, a higher SCE frequency was observed in chromosomes #1, #2, #3, and B, C + X, E, F chromosome groups than in controls. SCE levels were significantly higher in lymphoma patients in all chromosome numbers and groups mentioned than in patients with lymphadenitis. It is suggested that the high SCE rate in the malignant lymphoma population is possibly related to an increased chromosomal instability.     

The response of cells from patients with Huntington's chorea to mutagen-induced chromosome damage

Cultured blood lymphocytes from 15 patients with Huntington's chorea (HC) and matched controls were exposed to a series of graded doses of mitomycin C and ethyl methane sulphonate and examined for the incidence of sister chromatid exchange (SCE). The spontaneous SCE levels did not differ between HC patients and controls and although cells from the majority of HC patients showed a slightly enhanced response to SCE induction by the mutagens, the enhancement was small and significant only on the pooled data. Cultures from 4 HC patients and controls were exposed to a graded series of X-ray exposures and no difference was observed in the spontaneous aberration frequencies between HC cells and controls, or in their response to aberration induction by X-rays. Skin fibroblast cultures derived from three HC patients, two xeroderma pigmentosum patients and two healthy controls were exposed to MMC and the levels of unscheduled DNA synthesis determined. There was no difference between the response of HC cells and normal controls, although such synthesis in the xeroderma cells was severely depressed. It is concluded that: (i) fibroblasts and lymphocytes from HC patients show a normal response to the three mutagens studied; (ii) there is no evidence for any defect in processes involved in repairing the lesions induced; (iii) the slightly elevated response of HC lymphocytes to SCE induction may reflect the presence of a different proportion of a slightly more sensitive T cell sub-set in HC patients, and (iv) HC cells do not show a hypersensitivity to mutagens that could be used as a basis for diagnosis.     

Sister chromatid exchange frequency in breast cancer cases.

Sister chromatid exchange (SCE) were studied in 22 patients with breast cancer (i.e., four stage II; 12 stage III, six stage IV) and 10 normal healthy females as age-matched controls. The data obtained in these cases followed a Poisson distribution. An apparent increase in the average rate of SCE/cell was observed with the advancing stage of breast cancer.     

Chromosome Aberrations and Sister Chromatid Exchange Studies in Patients with Prostate Cancer: Possible Evidence of Chromosome Instability

Cytogenetic studies have been carried out using the G-banding technique in peripheral blood lymphocytes of 24 patients with prostate cancer. Of these, eight belong to stage B, six to stage C/e, three to C/sv, two to Do, and the remaining five to DI stage of carcinoma. Simultaneously, sister chromatid exchanges (SCEs) were also analyzed in the peripheral blood lymphocytes of these patients, along with those of 40 age-matched control subjects. The frequency of aberrant metaphases is significantly higher in patients with prostate cancer (7.32%) than in age-matched controls (2.92%). A large number of chromosome aberrations in lymphocytes of these patients, which are generally constitutional in nature, have also been detected. In stage-B patients, the frequency of cytogenetically abnormal cells is comparatively low with regard to the number of cells scanned, and these abnormalities are generally confined only to single chromosome (except in one metaphase in patient 1, who was diagnosed with bladder carcinoma in addition to cancer of the prostate). Sister chromatid exchanges (SCEs) were also analyzed in the patients and age-matched control subjects. The mean SCE frequencies were 9.24 ± 0.62 (n = 1356) per metaphase and 0.203 per chromosome in patients, whereas in control subjects the frequencies were 5.94 ± 0.25 (n = 4000) per metaphase and 0.129 per chromosome. The SCE frequency in cancer patients was statistically significant (p < 0.001). Our results indicate that the patients with prostate cancer show a degree of chromosomal instability that might be related to a predisposition to neoplasia.     

内蒙古地区精神分裂症患者的细胞遗传学研究

目的检测和比较精神分裂症患者和正常人群的SCE和两种遗传标记,分析特点、探讨精神分裂症的遗传特点.方法采用外用血淋巴细胞姐妹染色单体差别染色法检测技术、银染方法和微量淋巴细胞毒试验测定44例蒙汉族精神分裂症患者和60名健康人的外周血淋巴细胞染色体姐妹染色单体交换(SCE)、核仁组织区(NOR)的活性和人白细胞抗原(A位点抗原和 B位点抗原分布频率).结果精神分裂症患者的SCE频率明显高于正常对照组;细胞增殖速度低于正常组、患者组银染核仁组织区(AgNOR)活性比正常人群低;病例组 HLA的A9,A30,B5,B12抗原频率明显高于对照组.结论精神分裂症发病与遗传因素相关.     

Spontaneous and mutagen induced sister chromatid exchange in multiple sclerosis.

Spontaneous and mutagen induced sister chromatid exchange (SCE) frequencies have been studied in nine patients with multiple sclerosis and in nine age and sex matched healthy controls. The incidence of spontaneous SCE in lymphocytes of the MS patients was significantly greater, by about 50%, than in those of the control subjects. When exposed to mitomycin C (MMC) or ethyl methane sulfonate (EMS) in vitro, cells from both groups showed typical dose dependent increases in SCE frequency, with yields from MS patients slightly higher than from controls. The higher SCE yields in mutagen treated MS cells relative to controls is considered to reflect initial basal differences between the cell types, so that MS cells are not intrinsically hypersensitive to mutagen treatment.     

Apparent enhanced response to the induction of sister chromatid exchange by mitomycin C in myotonic dystrophy.

The spontaneous and mitomycin C (MMC) induced sister chromatid exchange (SCE) frequencies were examined in five adults with myotonic dystrophy (MD). There was no significant difference in the spontaneous incidence of SCE between MD patients and controls. However, a significantly enhanced response to the induction of SCE by MMC was observed in three of the five MD patients who were severely affected, while no such enhancement was observed in the other two mildly affected cases. These results suggest that the raised response may be a secondary consequence associated with disease progression. No differences were observed between the proliferating rate in vitro of lymphocytes of severe and mild cases of MD and controls, but the severe cases showed a significant increase in the proportion of T cells in peripheral blood. It is suggested that the observed enhanced response to MMC may reflect an increase in the proportion of a more sensitive subset of T cells in the peripheral blood.     

Some comments on sister chromatid exchange (SCE) in human neoplasia

The incidence of sister chromatid exchange (SCE) in bone marrow cells and/or lymphocytes of patients with various leukemias and the effects of drugs on the SCE incidence in the cells of patients with leukemia or cancer are presented and discussed. The possible use of SCE for screening antileukemic drugs, mutagenic and/or carcinogenic agents and susceptible human populations is presented.     

Sister chromatid exchange in lymphocytes of agricultural workers exposed to pesticides

Sister chromatid exchange (SCE) was studied in the lymphocytes of 27 agricultural workers occupationally exposed to several pesticides and 28 matched controls from el Maresme, an agricultural area near Barcelona. Comparison between both groups with the t-test did not reveal significant differences. These negative findings suggest that, possibly, the exposure level is too low to increase SCE in human lymphocytes in vivo. Our results indicate that smokers, both the workers and the controls, had a higher SCE frequency than non-smokers, in agreement with previous data reported by different authors.     

Sister chromatid exchange in cancer

Sister chromatid exchange (SCE) techniques have been shown to have great potential for use in the in vitro screening of suspected mutagens and carcinogens. Application of these techniques to bone marrow cells and/or lymphocytes from patients with various hematologic malignancies has demonstrated significant abnormalities in SCE frequencies in some of these diseases, as well as showing drug treatment effects. Interpretation of abnormal SCE findings in cancer patients is currently hindered by the lack of a clear understanding of the basic molecular and biochemical mechanisms involved in SCE formation. The potential practical use of SCE techniques in the diagnosis and treatment of cancer can not adequately be appreciated until this basic understanding is achieved.