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Background: 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 Methods : 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.

Results: 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.

Conclusion: 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. Iran . J. Radiat. Res. 2003 1(1): 29 - 35.

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  ABSTRACT

Background: Invasion  by  different  kinds  of  ballast  water  microorganisms  is  one  of  the  most important  marine  environment  problems  around  the  world therefore  preventing the  invasion  of  these  unwanted  and  harmful  stowaways  is  one  of  the  main strategies  of  responsible  agencies.  Some  of  these  methods  such  as  ocean exchange,  heating,  filtration,  hydro cyclones, UV irradiation and  chemical treatment,  have  various  problems  such  as  technical  deficiency,  high  costs,  lack  of  safety  and  environmental  side effects.  Materials and Methods: A novel system of treatment by Gamma irradiation is designed to irradiate the blast water uniformly and effectively. To determine the dose distribiution as a function of distance from the irradiation source, the MNCP code was used. The systems used for source implant in this simulation were Paterson-Parker, Paris and Network systems. In each system, Sivert-integral and inverse square law were used in Matlab program to determine the dose distribiution. Results: Results  of  initial  laboratory  tests  on  offshore  water  samples  of  Siri  Island indicated  that  the  appropriate  dose  for  deactivation  of  organisms  of  water  samples  is  approximately  one  kGy. It has been demonstrated  that  the  dose  can be  provided  by  twenty  five  100,000  Ci  line  sources  of  ⁶⁰Co  in  a  triangle  implant arranged  in  a  1x1x1  m³  cubic  shape  water  pipe.  In  order  to  increase  efficiency  and  radiation  safety,  water passed  from  two  other  coaxial  and  bigger  cubes,  after  passing  from  the  first  cube. A one  meter  thick  wall  of  concrete  around  the  cubes  was adequate to shield  the system completely. Conclusion: The  main advantages  of  this  system  such  as  high  efficiency,  safety,  reliability,  minimum  environmental adverse  effects,  proves  that  this  novel  method  not  only can  be used  for  ballast  water  treatment,  but  is  also  effective  for  drinking  water  purification.

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Background: The equivalent dose in the human body due to the natural gamma-emitting radionucides (238U, 232Th and 40K) in the surface soil surrounding the Consolidated Tin mine site in Bukuru-Jos, Nigeria has been determined in this study. Materials and Methods: Measurements of the soil natural radioactivity were made using a multi-channel pulseheight analyzer (Canberra Series 10 plus) coupled to a 76 mm×76 mm Nal (Tl) scintillation detector. Results: The mean concentrations obtained for each of the radionuclides is 35.4±17.6 Bq/kg for 40K 776.0± 158.0 Bq/kg for 238U and 2.72±0.58 kBq/kg for 232Th. The mean absorbed dose rate due to natural radioactivity calculated at a height of 1.0 m above the ground is 2.16 µGy/hr which converts to an equivalent dose of 3.0 mSv/y. Conclusion: The results obtained in this study are far above the world average equivalent dose of 0.41 mSv/y but lower than the annual limit of 20 mSv/y for radiation workers but still represents a health risk to workers on the site.

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Premature Chromosome Condensation (PCC) appears to have a possible utility for biological dosimetry purposes. The PCC technique may be adapted for cases of suspicion of overexposure where sampling is performed at least one day after an accident. For this purpose, human blood samples were exposed in vitro to 60Co up to 10 Gy and the PCC technique was performed immediately after irradiation. Analysis of excess PCC fragments distribution showed an over dispersion and the dose- effect relationship was best characterized by linear regression. Iran. J. Radiat. Res., 2009 6 (4): 213-218

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Background: To evaluate the effects of hyperthermia (HT) on the frequency of chromosomal aberrations induced by a low dose of neutron or γ-rays in human peripheral blood lymphocytes. Materials and Methods: Blood samples were exposed to HT (41.5°C for 30 and 60min, 43°C for 15 and 30min), 10 cGy neutron or γ-rays, HT + neutron/γ, and neutron/γ + HT. After standard cell culture, harvesting, fixation and staining, the chromosomal damages were scored in metaphase plates. Results: HT alone at 41.5°C did not induce chromatid or chromosome aberrations, however, the frequency of damages was significantly higher at 43°C (P<0.05). Furthermore, the chromosomal damages was significantly different when cells were irradiated with neutron or γ-rays alone (P<0.01). HT 1 hr post neutron/γ irradiation significantly induced higher chromosome damages in comparison to HT 1 hr before irradiation (P<0.05). The chromosomal damages were remarkably higher when cells were irradiated with neutron then heated at 43°C for 30 min. Conclusion: Since increasing frequency of chromosome damages increases probability of cell death, application of HT after neutron irradiation (instead of X– or γ- rays) might be considered as a procedure for cells killing in radiotherapy. Iran. J. Radiat. Res., 2009 7 (2): 69-77

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Background: The characteristics of secondary neutrons in a high energy radiation therapy room were studied using the MCNPX Monte Carlo (MC) code. Materials and Methods: Two MC models including a model with full description of head components and a simplified model used in previous studies were implemented for MC simulations. Results: Results showed 4-53% difference between full and with the simplified model in the neutron fluence calculation. Additionally, in full MC model, increase in the field size decreased the neutron fluence but for simplified model, increase in the field size led to increase in neutron fluence. In calculating the neutron and capture gamma ray dose equivalent, simplified model overestimated (9-47%) and (20-61%) respectively in comparison to the full simulated model. However, a close agreement was seen between two models, for field size of 10×10 cm2. Conclusion: for MC modeling of photoneutrons and capture gamma in radiotherapy rooms, the detailed modeling of linac head instead of simplified model is recommended. Iran. J. Radiat. Res., 2010 8 (3): 187-193

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Background: The effect of natural background radiation on health is still controversial. However, it is clear that it depends on the dose received by the population. The estimation of external natural background gamma rays received by the population of Caspian coastal provinces in the northern part of Iran was the main goal of this study. Materials and Methods: Gamma rays was measured using calibrated radiation survey meter in 51 urban and rural health centers randomly to estimate the exposure to population (Total population = 6888118 persons) in residential areas of Gilan, Mazandaran and Golestan (Total area 59240 Km²) as Caspian coastal provinces, North of Iran. Results: Results showed that the average dose rate in the areas under study was about 60.37±14.88 nSv/h or 0.53 mSv/yr (Range 30 to 90 nSv/h or 0.26 to 0.79 mSv/yr). The data from Ramsar was excluded from the estimation because of its very high natural background radiation (Max. 240 mSv/yr). No significant difference was found among the doses of the provinces (P=0.237). Conclusion: The external natural background gamma ray dose to the population of Caspian coastal provinces, North of Iran, was found to be almost equal to the average value in the world (0.5 mSv/yr). Iran. J. Radiat. Res., 2011 9(3): 183-186

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Background: Quantification of radiation-induced apoptosis in peripheral blood lymphocytes (PBLs) has been proposed as a possible screening test for cancer-prone individuals and also for the prediction of normal tissue responses after radiotherapy. Materials and Methods: The neutral version of the comet assay (single-cell gel electrophoresis) was used 24, 48, 72 hours after irradiation with 8 Gy gamma rays to assess interindividual differences in gamma rays-induced apoptosis in peripheral blood leucocytes between a panel of 30 normal individuals, and 30 breast cancer patients who hadn’t received radiotherapy or chemotherapy previously. Slides were stained with ethidium bromide and comets were assessed using visual and computer analysis. Results: In all incubation times, the baseline and radiation induced apoptosis values were higher in breast cancer patients compared to normal individuals which were significantly different (p<0.01). Although, both baseline and radiation induced values were higher in young breast cancer patients, the age did not seem to have a significant effect on apoptosis values both in cancer cases and controls. Conclusion: The increased rate of apoptosis observed in the leukocytes of breast cancer cases might be associated with their deficient DNA repair mechanisms. This finding might indicate that the radiation induced apoptosis could have some predictive potential. However, large interindividual variation has been a drawback. More studies are required to investigate the causes of interindividual variation and how it might be minimized. Iran. J. Radiat. Res., 2012 9(4): 237-244

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Background: Hydrogen peroxide (H2O2), produced by gamma ray irradiation to watery solution, was used as an analytical parameter for dosimetry of cobalt-60 (60Co) radiation. Materials and Methods: Detection of the produced H₂O₂ was carried out using two methods: an amperometric biosensor fabricated by immobilization of anthraquinone 2-carboxylic acid modified horseradish peroxidase on glassy carbon electrode, and chemiluminescence technique using luminol as a fluorophore and diperiodatocuprate as a catalyst. Results: In the first method, at the applied potential of -550 mV (vs. Ag/AgCl) the biosensor showed the sensitivity of 74.46 nA/Gray and detection limit of 0.061 Gray (R.S.D=3.67% for N=3) towards H₂O₂ produced by ⁶⁰Co. In the second method, the sensitivity and detection limit for ⁶⁰Co gamma ray was determined to be 2.34 (luminescence intensity/Gray) and 0.069 Gray (R.S.D=4.16% for N=3), respectively. Conclusion: The obtained results revealed that both proposed techniques, with leaner range from 0.25 to 5 Grays are applicable for detection and dosimetry of gamma ray from ⁶⁰Co.

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Background: Seaweeds contain significant quantities of lipids, protein, vitamins and minerals. Aquavac Ergosan contains 1% alginic acid extracted from two brown seaweeds, Laminaria digitata and Ascophyllum nodosum. Both in vivo and in-vitro researches have mainly been focused on the effect of Ergosan on fish growth, survival rate, reproductive performance and innate immunity in blood and epidermal mucus. Despite numerous studies on the effects of Ergosan on immune system of aquatic animals and evaluation of seaweeds in proximate analysis, there is no data available on proximate analysis of irradiated Ergosan extract (alginic acid). Therefore, the aim of this study was to assess the effect of on different groups of irradiated alginic acid (10, 20, 30, 40 and 50 KGy) for analyzing proximate composition. Materials and Methods: Alginic acid was prepared from the sonicated Ergosan extract. The Alginic acid extracted from Ergosan was irradiated with a gamma cell. The protein and lipid content and Moisture and ash were recorded. Results: Statistical analysis showed no significant differences among all of groups in terms of protein, lipid, ash and moisture. Conclusion: Radiation processing is a very convenient tool for imparting desirable effects in polymeric materials. The polysaccharide degradation by gamma or ultraviolet irradiation is free of initiators. High energy radiation technique can be effectively used to decrease the molecular weight of different polysaccharides such as alginate and Chitosan. Based on the results of this study, gamma irradiation of alginic acid as natural polysaccharide had no effect on crude protein, crude lipid, moisture and ash.