Antoni Subias

Cytogenetic analysis of lymphocytes from hospital workers occupationally exposed to low levels of ionizing radiation

Cytogenetic studies were performed in lymphocytes from hospital workers exposed to low doses of radiation (1.6-42.71 mSv). When compared with controls, exposed workers showed a significant increase in structural chromosome-type aberrations, acentric fragments being the most frequent alteration. Our results suggest that acentric fragments are good indicators of exposure to very low doses of radiation, although no dose-effect correlation was observed. The incidence of numerical abnormalities (hyperdiploidy) was significantly increased.

Chromosome abnormalities in peripheral blood lymphocytes from untreated Hodgkin's patients

SummaryWe describe the presence of a high frequency of spontaneous chromosome aberrations in lymphocytes from six untreated patients with Hodgkins disease. The characteristics of the chromosome abnormalities observed suggest the existence of a certain degree of chromosome instability in these cases, that could be a predisposing factor for the development of malignancies.

Decreased sensitivity to the cytogenetic effects of bleomycin in individuals occupationally exposed to ionizing radiation

In the present work, 12 individuals occupationally exposed to ionizing radiation and 11 unexposed ones were studied to determine the cytogenetic effect of a challenge dose of bleomycin on their phytohemagglutinin stimulated lymphocytes. After bleomycin treatment, the frequencies of chromatid breaks and gaps were significantly lower in the exposed population (p < 0.025 for both types of chromatid alterations). These results could indicate that occupational exposure to ionizing radiation can induce an adaptive response that can be detected by a subsequent treatment with bleomycin.

Establishment and validation of a dose-effect curve for γ-rays by cytogenetic analysis

Abstract A dose-effect curve obtained by analysis of dicentric chromosomes after irradiation of peripheral blood samples, from one donor, at 11 different doses of γ-rays is presented. For the elaboration of this curve, more than 18 000 first division metaphases have been analyzed. The results fit very well to the linear-quadratic model. To validate the curve, samples from six individuals (three controls and three occupationally exposed persons) were irradiated at 2 Gy. The results obtained, when compared with the curve, showed that in all cases the 95% confidence interval included the 2 Gy dose, with estimated dose ranges from 1.82 to 2.19 Gy.

Chromosomal instability in breast cancer patients

SummaryWe have carried out cytogenetic studies, using the G-banding technique, in peripheral blood lymphocytes of 10 patients affected by breast carcinoma. The frequency of aberrant metaphases (7.36%) is significantly different from that of our laboratory controls (3.76% of aberrant metaphases) but not from that detected in patients suffering from bladder cancer (10.64%) and Hodgkins disease (11.03%), two conditions that have previously been described as chromosomally unstable. Our results suggest that breast carcinoma patients show a degree of chromosomal instability that could be related to a predisposition to neoplastic disease.

Chromosome instability in bladder carcinoma patients.

The relationship between the presence of a high frequency of chromosome aberrations and a predisposition to cancer has been well established in the so-called chromosome instability syndromes. Chromosome instability is also present in a variety of patients affected by cancer, and sometimes in their healthy relatives. We present a cytogenetic study carried out in lymphocytes from 13 untreated bladder carcinoma patients (only four of them had a history of occupational exposure to mutagens). Percentages of aberrant metaphases were significantly higher in cancer patients than in controls. Of the total number of chromosome aberrations in cancer patients, 67.16% corresponded to major structural chromosome abnormalities, while 25.37% were gaps or breaks. Numerical abnormalities represented 7.46% of the total. The bands more frequently involved in chromosome rearrangements were 5q31 and 1q32. Our results tentatively indicate that a significant proportion of patients with bladder carcinoma may have an underlying inherent chromosome instability. An age effect cannot be excluded, but we did not find significant differences between patients over 50 years of age and patients under 50 years of age.

Cytogenetic effects of radiotherapy: frequency and types of chromosome aberrations.

The frequency and types of chromosome aberrations induced by ionizing radiation in cancer patients were evaluated in 24 cases studied just before and immediately after radiotherapy. The incidence of aberrant metaphases prior to treatment was 9.98% and increased significantly after treatment to 32.8%. The frequency of chromosome aberrations before radiotherapy was, with the exception of the cases of breast cancer and seminoma, significantly higher than that in our laboratory controls. A comparison of chromosome abnormalities observed before and after treatment indicated that dicentric translocations, rings, and reciprocal translocations increased by a factor of 23, 13, and 11, respectively, after radiotherapy. Ionizing radiation produces more asymmetrical than symmetrical chromosome aberrations and more two-break than one-break anomalies.