Transient cytotoxicity of 131I beta radiation in hyperthyroid patients treated with radioactive iodine.

Background & objectives: Radioiodine (131I) or radioactive iodine in low doses is used worldwide as the first line of management in the treatment of hyperthyroidism. Information is available on the extent and severity of cell damage after a high dose radioiodine (131I) therapy for thyroid cancer, but information is scanty on its cellular effects, its extent and severity of cell damage after a low dose 131I therapy. The present investigation was aimed to study the cytotoxic effects of a low dose 131I therapy in varying doses as is normally being used in routine clinical practice in the treatment of various forms of hyperthyroidism. Methods: Peripheral blood lymphocytes were analyzed in 32 hyperthyroid patients. All of them received 131I in the form of sodium iodide solution orally. Blood lymphocytes were studied for the presence of chromosomal aberrations (CA) and micro nucleus (MN) using micronucleus assay. Blood samples of these patients were drawn prior to the treatment, on 7 thand 30 thdays after the treatment. Results: The results indicated a positive relationship between 131I dose, CA and MN frequency. A statistically significant increase in CA and MN frequency in day 7 post- therapy and a decrease in mean levels of CA and MN on day 30 post-therapy were observed when compared to pre-therapy. Interpretation & conclusions: This study showed that the cytogenetic damage induced by 131I in low doses i.e., less than 555MBq was minimal and reversible. Patients can be motivated to undertake this safe and easy procedure as a first line of therapy in the treatment of hyperthyroidism.

[ genotoxic effects of mobile phone waves on induction of chromosomal damages in embryos of Balb/C mice]

In recent years, the widespread use of microwave producing instruments specially mobile phones; result in growing concern regarding the possible effects associated with these waves on human health. In the present study investigated the genotoxic effects of mobile phone radiation in adult mice [Balb/C] and their embryos. In this experimental research pregnant mice were irradiated with mobile phone for 4 days during gestational period from 14th to 18th days of gestation for 6h/day from 9AM until 15PM]. At the end of treatment period, euthanized the dams on day 18.5. Then embryos in 18.5th day of gestation were extracted. At first the morphology of embryos was studied, then documented their weight and CR length. For assessment of possible genetic damages in erythrocytes the blood was taken from their hearts and smear was prepared. Spleen tissue was prepared for histological studies. Smear was prepared from peripheral blood and bone marrow of mice and stained with May Grunowald and Gimsa. Data were analyzed using t-test and ANOVA. In experimental group, mobile phone radiation decreased embryos weight [P=0.04] but no change was observed in CR length. Megakaryocytes and red blood cells of spleen were significantly increased [P=0.002 and P<0.05, respectively]. However, lymphocytes.numbers and micronucleus frequency in peripheral blood erythrocytes in experimental embryos and pregnant mice did not change. Interestingly, micronucleus frequency in polychromatic erythrocytes of bone marrow of pregnant mice was significantly increased [P <0.001]. Mobile phone radiation [940 MHZ] had genotoxic effects and increased micronucleus formation in polychromatic erythrocytes of bone marrow in pregnant mice

Potent radioprotective effect of therapeutic doses of ranitidine and famotidine against gamma - rays induced micronuclei in vivo

Previous investigations have revealed, cimetidine, a histamine H2-receptor antagonist, show radioprotective effects against gamma- and neutron-induced micronuclei in bone marrow erythrocytes. In this study, the anticlastogenic effects of famotidine and ranitidine, which act similar to cimetidine as histamine H2-receptor antagonists, was investigated. Materials and Balb/c male mice were injected i.p. with various doses of famotidine and ranitidine two hours before 2 Gy gamma irradiation. Frequency of micronuclei was determined in bone marrow erythrocytes following each treatment. The results indicated that gamma irradiation alone can cause a high frequency of micronuclei formation and decrease cell proliferation ratio. Pre-irradiation injection of famotidine and ranitidine, of various doses, effectively reduced the number of micronucleated polychromatic erythrocytes [MnPCEs], yet has no effect on cell proliferation ratio [PCEs/PCEs+NCEs]. In fact, these two drugs reduce the clastogenic effects of gamma rays, while they are ineffective against the cytotoxic properties of gamma rays. The dose reduction factor [DRF] calculated, shows a DRF=2 for famotidine and a DRF=1.8 for ranitidine which is indicative of a high radioprotective property of these drugs. The mechanism in which these drugs reduce clastogenic effect of gamma radiation is not fully understood. It might be due to their antioxidant and free radical-scavenging properties

Frequencies of Micronuclei in Peripheral Lymphocytes in Korean Populations after Chronic Low-dose Radiation Exposure

The purpose of this study was to estimate predictive markers of intrinsic radiosensitivity in individuals who were exposed to occupational or environmental radiation. Throughout this process, the actual biohazard risks and base-line chromosome damage were evaluated in human population. Further studies were carried out to provide evidence for the existence of individual variations in age-dependent responses through micronuclei (MN) assay.Spontaneous frequencies not only vary greatly between individuals, but also working or living areas. It was shown that the increased level of spontaneous cell with MN was observed with increasing age. The relationship between radiosensitivity and the increased spontaneous level of MN may be in an inverse proportion. Ionizing radiation may be targeted mutagenic effects at the usual exposures of background levels that populations were exposed. Age and gender are the most important demographic variables in determining the MN index with frequencies in females, which were greater than those in males. The main life-style factors influencing the MN index in subjects were correlated significantly and positively with smoke. The results showed that an indicator of the genetic damaged rate in MN index in human populations significantly correlated with age, sex and life-style factors. So far, it is evident that with regard to the application of MN assay all future studies have to take into account the influence of age, gender, and life-style.In Conclusion, using micronuclei assay technique a large population can be easily monitored. This study illustrated that the MN assay may provide a high potential to ensure appropriate quality control and standard documentation protocol that can be used to monitor a large population exposed to radiation epidemiologically.

Influence of novobiocin on gama-irradiation G0-lymphocytes as analyzed by cytogenetic endpoints

Experiments with novobiocin (NB) post-treatment were performed to verify its effect on the frequencies of micronuclei (MN) and chromosomal aberrations (CA) induced by g-irradiation (0.75, 1.5 and 3.0 Gy) in human lymphocytes at G0-phase. The frequencies of MN significantly decreased by 44 and 50 per cent, for the treatment with NB 50 µg/ml (30-min pulse) after radiation doses of 1.5 and 3.0 Gy, respectively. However, CA frequencies were not significantly affected. No significant effect on CA was observed when lymphocyte cultures were exposed to a single dose of 2.0 Gy at the G0-phase and posttreated with 25 µg/ml NB for three hours either immediately after irradiation (G0-phase) or after 24 h (S-phase). The significant suppressive effect of NB on MN frequencies supports the hypothesis that NB interaction with chromatin increases access to DNA repair enzymes.

Effects of nickel sulfate alone and with ultraviolet light on micronuclei frequency in cultured human lymphocytes

Comutagenic or cocarcinogenic activities have been reported between nickel compounds and UV light. The presence of micronuclei in a binucleated lymphocyte is regarded as. an alternative to classical cytogenic methods for monitoring chromosomal damage. The present study aimed to detect this comutagenicity as regards micronuclei induction. Human peripheral lymphocytes were treated with different concentrations of nickel sulfate and/or with UV light at 200 and 1000 ergs/mm[2]. Cells have been cultured and 100 binucleated cells were counted and the micronuclei frequency recorded. The observed values, for all concentrations of nickel sulfate combined with UV were less than expected for an additive response of two agents computed as the combined increase over the values of the control for the metal and UV alone. Caution is advised when interpreting cytogenic values in multiple exposures