Background: The aim of this study was to test the in vitro sensitivity of lymphocytes of patients with head and neck cancer against gamma irradiation and also to find out if the frequencies of chromosomal aberrations correlate with side effects of radiotherapy.Methods: Peripheral blood of 101 patients with head and neck cancer was collected before the onset of radiotherapy, cultured and irradiated in the G-2 or the G-0 phase of the cell cycle. Lymphocytes of 40 healthy donors were treated in the same way. Chromosomal aberrations such as chromosome and chromatid breakages, chromosome and chromatid gaps, chromatid exchanges and micronuclei were scored in metaphase cells of the patient and control groups.Results: The frequency of radiation- induced G2 aberrations in lymphocytes of patients were on average higher than that of healthy donors (P=0.001 for chromosomal breaks). The frequency of radiation-induced micronuclei in the G0 assay were also higher in patients than that in controls (P=0.05). The results also indicate that there is no correlation between the two assays. No significant correlation was observed between aberration frequencies in lymphocytes and the degree of both early and late normal tissue reactions.Conclusion: The induced chromosomal aberration frequencies in lymphocytes of patients with head and neck cancer are higher than those in healthy individuals, however, it does not appear to have a predictive value for the risk of developing side effects to radiotherapy.

Background: Radiotherapy is regarded as a standard treatment modality in breast cancer (BC). Radiation causes cellular damage both in cancer and normal cells by inducing DNA-damage and chromosomal aberrations (CA). Different agents were used for ameliorating effects of radiation, mainly antioxidants such as melatonin. Melatonin shows oncostatic properties on human BC. The aim of this study was to evaluate the modulating effect of melatonin on radiation induced CA in cells irradiated at G2 phase of the cell cycle. Materials and methods: G2 assay was applied on whole peripheral blood lymphocytes received from 10 BC patients and 5 normal controls. Blood culture was initiated in complete culture medium. Four h prior to harvesting, cells were irradiated with 1Gy gamma rays. Pretreatment of samples with melatonin was done 3 h before irradiation. After metaphase preparation and slide making, slides were stained in Giemsa. Hundred well spread metaphases were scored for the presence of chromatid type aberrations with a microscope at a magnification of × 1000. Result: Results indicated a high and significant frequency of CA both in lymphocytes of normal and breast cancer patient after irradiation; however, the frequency was much more in lymphocytes from BC patients. Pretreatment of samples with melatonin led to a considerable increase in the frequency of aberrations especially in lymphocytes of BC patient. Conclusion: Results showed that despite having antioxidant property, melatonin led to enhanced frequency of radiation induced CA in lymphocytes of BC patients.

Background: Inherent radiosensitivity associated with elevated chromosomal aberrations (CA) was shown in breast cancer (BC) patients at cellular level. Different agents were used to protect cells against adverse effects of ionizing radiation (IR), mainly antioxidants such as vitamins. The aim of this study was to evaluate the modulating effect of saffron extract on radiation induced CA in lymphocytes of normal individuals and BC patients. Materials and Methods: G2 assay was applied on whole peripheral blood lymphocytes received from 5 normal controls and 10 BC patients with luminal A subtype. Blood culture was initiated in complete culture medium, 4h prior to harvesting cells were irradiated with 1 and 2 Gy X-rays. Pretreatment of samples with saffron was done 2 h before irradiation. After metaphase preparation and slide making, slides were stained in Giemsa. Hundred well spread metaphases were scored for presence of chromatid type aberrations with a microscope at a magnification of 1000×. Result: Results indicated a high and significant frequency of CA both in lymphocytes of normal and BC patient after irradiation. Pretreatment of samples with saffron led to a significant increase in the frequency of breaks in lymphocytes of both normal individuals and BC patients. Conclusion: Results indicate that despite its antioxidant property, pretreatment of lymphocytes of normal individuals and BC patients with saffron before X-irradiation led to radiosentisizing effect. The way saffron sensitize lymphocytes to X-rays is not known, but it might be possible to inhibit repair of radiation induced DNA strand breaks.

We establish the existence of two rigid triples of conjugacy classes in the algebraic group G2 in characteristic 5, complementing results of the second author with Liebeck and Marion. As a corollary, the finite groups G2(5n) are not (2; 4; 5)-generated, conrming a conjecture of Marion in this case.

In this paper, we prove that chevalley groups G2(q), where q ≡,±, 2(mod 5) and q2 + q + 1 is a prime number, can be uniquely determined by the order of the group and the second largest element order.