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The aim of this study was to assess the radiosensitivity of bismuth sulfide nanoparticles conjugated with a synthetic agonist analog of gonadotropin-releasing hormones in targeted radiotherapy for breast cancer. After synthesis and characterization of nanoparticles, cytotoxicity of nanoparticles was measured by MTT assay, and the survival fraction was determined by colony formation assay. Finally, flow cytometry was performed to identify the mechanism of radiosensitization. Characterization results determined the spherical shape of Bi2S3@BSA with an average size of 8.649 ± 1.6 nm, and Fourier transform infrared confirmed the successful binding of triptorelin to the surface of the nanoparticles. MTT test results show that the Bi2S3@BSA–triptorelin did not cause any toxicity ( P < 0.05 ) even up to 75 μg/ml. At all doses of ionizing radiation, colony formation assays showed that the nontoxic concentration of Bi2S3@BSA–triptorelin significantly increased cell death in MCF-7 cells compared to Bi2S3@BSA ( P < 0.05 ). The apoptosis test also confirmed colony formation assay results at all doses and introduced apoptosis as a mechanism of radiosensitivity produced by nanoparticles. Certainly, targeted bismuth sulfide nanoparticles can be a good candidate for increasing radiosensitivity against tumor cells.

Background: Radiotherapy is thecrucial treatment for most malignancies, however; it has short and long-term side effects. The occurrence of secondary cancer following radiation-induced genomic instability in stem cells is an important long-term side effect of radiation therapy. The radiation response of human mesenchymal stromal cells (hMSCs) is critical in cancer patients who are treated with radiotherapy for hMSCs lifetime proliferative potential. Evaluation of genomic instability in human mesenchymal stem cells at different radiation doses and times, and examining the relative expression of some effective genes, have been the objectives of this study. Methods: After extraction, characterization, and expansion of hMSCs, they were irradiated for 0, 0.5, 2, and 6 Grays. Nuclear alterations were evaluated at 2, 10, and 15 days after irradiation using the cytokinesis-block micronucleus assay. As well as TP53, Bax, Bcl2, and KRAS gene expressions were analyzed 48 hours post-irradiation for genomic response evaluation. Results: The mean incidence of micronucleus, nucleoplasmic bridges, and nuclear buds incidences were 4.8±1.6, 47.6±6, and 18±2.6, respectively, 48 hours after the fourth passage in the non-irradiated (control) group for one thousand binucleated cells. Micronuclei incidences in 0.5, 2, and 6 grays radiation groups were 14.3±4.9, 32.3±6.5 and 55±9.1 respectively in 48 hours after irradiation and 12.6±1.5, 19±5.5, and 22.3±5.2, respectively ten days post-irradiations. Conclusion: Low levels of nuclear alterations as genomic instability markers were seen in various cell generations of control groups, which must be considered for cell therapy and regenerative medicine applications. In the irradiated groups, chromosomal aberration increased significantly with the dose, 2days post-irradiation due to a disproportionate increase in the Bax/Bcl2 ratio and high expression of the KRAS gene. significant nuclear alterations were seen in the tenth to fifteenth generations of irradiated hMSCs due to radiation-induced genomic instability which may persuade secondary malignancies in the following years after the radiotherapy treatment of patients.

This study was performed to specify the efficiency of imaging nanoparticle concentration as contrast media in dual‐energy computed tomography (DECT). Gold nanoparticles (AuNPs) and gold nanoparticles‐conjugated folic acid through cysteamine (FA‐Cya‐AuNPs) were both considered as contrast agents. Characterization of NPs was performed using Dynamic Light Scattering (DLS) and zeta potential. The hemocompatibility of NPs was confirmed by different blood parameters such as white blood cell, red cell distribution width, hemoglobin, lymphocytes counts and haemolysis assay. DECT algorithm was confirmed using calibration phantom at different concentrations of NPs and tube potentials (80 and 140 kVp). Then, DECT was used to quantify the concentration of both AuNPs and FA‐Cys‐AuNPs in human nasopharyngeal cancer cells. Mice were injected with non‐targeted AuNPs and targeted AuNps at a concentration of 3 × 103 μg/ml. Then, they were scanned with different tube potentials. The concentration of nanoparticles in the various organs of nude mice was measured through DECT imaging and inductively coupled plasma mass spectrometry (ICP‐MS) analysis. The results of DECT images were compared with ICP‐MS analysis and indicated that they were approximately similar. In sum, FA‐Cys‐AuNPs can be a proper candidate for targeted contrast media in DECT molecular scanning of human nasopharyngeal tumours.

The medicinal properties of herbs attract the public and the medical community’s attention. Turmeric is considered a natural substance with many health effects, and curcumin, as effective component of turmeric, is known to have several usefulness for human health. The dual effect of the curcumin in the presence of radiation as a radiosensitizer and radioprotector for tumor and normal cells, respectively, increases treatment efficacy. In this study we have investigated the effect of X-ray radiation (6 MV) and bulk curcumin, nano micelles, and nanoniosome of curcumin on two colorectal cancer cell lines and human fibroblast cells using MTT, colonogenic assay, and annexin-PI test. Based on the results, curcumin and the two formulations used decreased the viability of both cell lines, however the final results depend on the curcumin concentration. The results of the dose-response curve displayed that the survival fraction in the presence of nanomicelles had a dual function on cancerous and normal cells due to a radiosensitivity and radioprotective effects on cancerous and normal cells, respectively. However, these effects were not shown in the presence of nanoniosome of curcumin. Curcumin in all 3 forms increased apoptotic cells in both cell lines without any radiation. However, the apoptotic cells increased in exposed cancerous cells for all forms of curcumin, the apoptotic HFF cells decreased after radiation in presence of them. In conclusion, curcumin is considered a radiosensitizer in tumor cells, and its radioprotection properties need more studies.

The adaptive response (AR), which can be induced by low-dose ionizing radiation (LD), may influence the therapeutic ratio of cancer treatment. We investigated the AR and the DNA double-strand break (DSB) repair pathway in human lung tumor cells and normal cells. We measured viability and proliferation of normal lung cells (MRC-5) and lung cancer cells (QU-DB) using the MTT and colony formation assays. Flow cytometric analysis of γ-H2AX was used to measure DNA-DSBs induction, repair, and residual damages. AR was seen in the normal cells but not in the cancer cells. Our findings suggest that LD stimulates DSB repair and that this may contribute to distinctive AR in normal vs. cancer cells.

Resistance to cancer radiotherapy is one of the biggest concerns for success in treating and preventing recurrent disease. Malignant tumors may develop when they block genetic mutations associated with apoptosis or abnormal expression of apoptosis; Tumor treatment may induce the expression of apoptosis-related genes to promote tumor cell apoptosis. MicroRNAs have been shown to contribute to forecasting prognosis, distinguishing between cancer subtypes, and affecting treatment outcomes in cancer. Constraining these miRNAs may be an attractive treatment strategy to help overcome radiation resistance. The delivery of these future treatments is still challenging due to the excess downstream targets that each miRNA can control. Understanding the role of miRNAs brings us one step closer to attaining patient treatment and improving patient outcomes. This review summarized the current information on the role of microRNA-induced apoptosis in determining the radiosensitivity of various cancers.

The aim of the present study was the investigation of the effects of mobile phones at different daily exposure times on the hippocampal expression of two apoptotic genes. Forty-eight male BALB/c mice were randomly divided into six groups with 8 animals in each group. Four experimental groups were respectively exposed to electromagnetic waves for 0.5, 1, 2 and 4 hours twice a day for 30 consecutive days. One experimental group was radiated for 4 hours once a day, while the control group did not receive any radiation during the experiment. The expression of both

Purpose Radiotherapy plays a pivotal role in the treatment of cancer. One of the main challenges in this treatment modality is radiation-induced complications in some patients affected by high radiosensitivity (RS). The differences in RS are determined mainly by genetic factors. Therefore, identifying the genes and mechanisms that affect RS in different cells is essential for evaluating radiotherapy outcomes. In the present study, the ability to repair DNA double-stranded breaks (DSB) is evaluated, followed by examining the expression levels of CDKN1A (p21), cyclinD1, and Mre11 genes in human fibroblasts with different RSs. Materials & methods Cellular RS was measured by survival fraction at 2 Gy (SF2). The γ-H2AX assay was used for assessing DNA repair capacity. Eventually, gene expression levels from each cell line 4 and 24 h after irradiation (at 2, 4, and 8 Gy) were measured by real-time PCR. Results The SF2 values for the cell lines ranged from 0.286 to 0.641, and RS differences of fibroblast cells were identified. Among the studied genes, the expression of Mre11 was the most important. Analysis of the real-time PCR data showed that changes in Mre11 gene expression (4 h after 8 Gy irradiation) were directly correlated with the RS (R2 = 0.905). The difference in the expression of the p21 gene (4 h after 4 Gy irradiation) was also promising. Finally, the flow cytometry analysis showed that the radioresistant cell lines quickly repaired DBS damages. However, the repair process was slow in the radiosensitive cell line, and the residual damage is significantly higher than other cell lines (P Conclusions This study indicates that changes in the expression of p21 and Mre11 genes play an important role in cell response to radiation and thus these genes can be introduced as biomarkers to predict RS in normal cell lines.

Introduction: Radiotherapy is a crucial component of treatment for ∼70% of all cancer patients. The identification of effective biomarkers of radiosensitivity (RS) is a fundamental goal of radiobio...

The purpose of this study is to measure the concentration of gold nanoparticles (AuNPs) attached to folic acid through cysteamin as the linker (FA‐Cys‐AuNPs) and AuNPs in KB human nasopharyngeal cancer cells using dual‐energy CT (DECT). In this study, nanoparticles with a size of ∼15 nm were synthesized and characterised using UV‐Vis, TEM, FTIR and ICP‐OES analyses. The non‐toxicity of nanoparticles was confirmed by MTT assay under various concentrations (40– 100 µg/ml) and incubation times (6, 12 and 24 h). To develop an algorithm for revealing different concentrations of AuNPs in cells, a corresponding physical phantom filled with 0.5 ml vials containing FA‐Cys‐AuNPs was used. The CT scan was performed at two energy levels (80 and 140 kVp). One feature of DECT is material decomposition, which allows separation and identification of different elements. The values obtained from the DECT algorithm were compared with values quantitatively measured by ICP‐OES. Cells were also incubated with AuNPs and FA‐Cys‐AuNPs at different concentrations and incubation times. Subsequently, by increasing the incubation time in the presence of FA‐Cys‐AuNPs, in comparison with AuNPs, DECT pixels were increased. Thus, FA‐Cys‐AuNPs could be a suitable candidate for targeted contrast agent in DECT molecular imaging of nasopharyngeal cancer cells.

Glioblastoma (GBM) is the most lethal type of primary brain tumor. Currently, even with optimal and multimodal cancer therapies, the survival rate of GBM patients remains poor. One reason for inadequate response of GBM tumors to radiotherapy is radioresistance (RR). Thus, there is a critical need for new insights about GBM treatment to increase the chance of treatment. microRNAs (miRNAs) are important regulatory molecules that can effectively control GBM radiosensitivity (RS) by affecting radiation-related signal transduction pathways such as apoptosis, proliferation, DNA repair and cell cycle regulation. miRNAs provide new clinical perspectives for developing effective GBM treatments. A growing body of literature has demonstrated that GBM RS can be modified by modulating the expression of miRNAs such as miR-7, miR-10b, miR-124, miR-128, miR-320, miR-21, miR-203, and miR-153. This paper highlights the miRNAs and the underlying molecular mechanisms that are involved in the RS of GBM. Besides highlighting the role of miRNAs in different signaling pathways, we explain the mechanisms that affect RS of GBM for modulating radiation response at the clinical level.

The development of various cost-effective multifunctional contrast agent for specific targeting molecular imaging of tumors presents a great challenge. We report here the in vivo targeting imaging of folic acid (FA) gold nanoparticles (AuNPs) through cysteamine (Cys) linking for targeted of human nasopharyngeal head and neck cancer by computed tomography (CT). The toxicity of nanoparticles in kidney, heart, spleen, brain and liver was evaluated by H&E (hematoxylin and eosin) assay. We showed that the formed FA-Cys-AuNPs with an Au core size of ˜13 nm are non-cytotoxic in the particle concentration of 3 × 103 μg/ ml. The nude mice were scanned using a 64-slice CT scan with parameters (80 kVp, slice thickness: 0.625 mm, mAs: 200, pitch: 1). CT scan was performed before and after (Three and six hours) I.V (Intra Venous) injection of AuNPs and FA-Cys-AuNPs. The distribution of nanoparticles in the nude mice was evaluated by imaging and coupled plasma optical emission spectrometry (ICP-OES) analysis. The findings clearly illustrated that a small tumor, which is undetectable via computed tomography, is enhanced by X-ray attenuation and becomes visible (4.30-times) by the molecularly targeted AuNPs. It was further demonstrated that active tumor cells targeting (FA-Cys-AuNPs) is more specific and efficient (2.03-times) than passive targeting AuNPs. According to the results, FA-Cys-AuNPs can be employed as a promising contrast agent in CT scan imaging and maybe in radiotherapy that require enhanced radiation dose.

Introduction: In the present study, the radioadaptive role of the immune system induced by low dose (LD) was investigated for its in vivo protective activity. Materials and Methods: Quantitative analysis of cytokine gene expression was assessed for their in vivo activity in BALB/c mice. To evaluate the adaptive response induced by LD on the mice spleen lymphocyte, the cytokine interleukin (IL)-4, interferon (IFN)-γ, and transforming growth factor (TGF)-β expression was measured by a real-time quantitative polymerase chain reaction. To verify the radioadaptive effect of LD, animals were preirradiated at 10 cGy from a 60 Co source and then challenge dose at 200 cGy was delivered. Independent sample student's t-test was employed to compare cytokine gene expression in radioadaptive (10 + 200 cGy), LD (10 cGy), high-dose (HD, 200 cGy), and control groups of animals. Results: Following the HD, the cytokine gene expression of IFN-γ, IL-4, and TGF-β was significantly decreased compared to the control group (P = 0.0001). However, TGF-β expression was also decreased significantly in the LD and adaptive groups compared to the control group (P = 0.0001). IFN-γ/IL-4 ratio in the adaptive group was significantly decreased compared to the HD group (P = 0.0001). Conclusion: These results indicate that the immune system plays an important role for radioadaptive response induction by LD radiation to adjust the harmful effects of HD irradiation.

Introduction: Radiation-induced bystander effects (RIBE) is the radiobiological effects detected in nonirradiated cells that have received signals from neighboring irradiated cells. In some studies, there are observations that RIBE unexpectedly reduces at high doses. In this study, the expression of two selected apoptotic and repair genes and their possible role in the formation of this unexpected reduction is examined. Materials and Methods: The QU-DB cells were irradiated with gamma rays of a60 Co teletherapy unit at doses of 2, 4, 6, and 8 Gy. One hour following irradiation, their culture media were transferred to bystander cells to induced RIBE. After 24 h incubation, the RNA of cells was isolated and cDNA synthesized. Expression levels of BAX, XPA, and XPA/BAX ratio were examined by relative quantitative reverse transcription-polymerase chain reaction. Results: In target cells, up-regulation of both genes was observed at all doses. In bystander cells, at the low dose (2 Gy), the expression of BAX was more than XPA; at 4 Gy, the ratio was balanced. A significant correlation was found between the XPA/BAX ratio and the dose, at high doses pattern of gene expression dominated by DNA repair gene. Conclusion: Gene expression profile was distinctive in bystander cells compared to target cells. The observed linear increasing of the ratio of XPA/BAX could support the hypothesis that the DNA repair system is stimulated and causes a reduction in RIBE at high doses.

With the development and applications of ionizing radiation in medicine, the radiation effects on human health get more and more attention. Ionizing radiation can lead to various forms of cytogenetic damage, including increased frequencies of micronuclei (MNi) and chromosome abnormalities. The cytokinesis block micronucleus (CBMN) assay is widely used method for measuring MNi to determine chromosome mutations or genome instability in cultured human lymphocytes. The visual scoring of MNi is time-consuming and scorer fatigue can lead to inconsistency. In this work, we designed software for the scoring of in vitro CBMN assay for biomonitoring on Giemsa-stained slides that overcome many previous limitations. Automatic scoring proceeds in four stages as follows. First, overall segmentation of nuclei is done. Then, binucleated (BN) cells are detected. Next, the entire cell is estimated for each BN as it is assumed that there is no detectable cytoplasm. Finally, MNi are detected within each BN cell. The designed Software is even able to detect BN cells with vague cytoplasm and MNi in peripheral blood smear. Our system is tested on a self-provided dataset and is achieved high sensitivities of about 98% and 82% in recognizing BN cells and MNi, respectively. Moreover, in our study less than 1% false positives were observed that makes our system reliable for practical MNi scoring.

Introduction & Objective: Supra condylar humeral fractures are frequent in children at 5-8 years old and its neurovascular complications are more than other fractures. Treatment of displaced fractures (type3) is surgical with open reduction and internal fixation, through posterior, medial, lateral or anterior approach. This study is performed for comparison of the effect of posterior or lateral approach over range of movement of elbow in type 3 supra condylar humeral fractures that were treated with open reduction and internal fixation. Materials & Methods: This study was clinical trial and the studied subjects were consisted of 50 patients at 5-12 years old with type 3 of supra condylar humeral fractures. Patients were operated randomly by one of posterior or lateral approaches. Average range of movement of operated elbows in each group were measured post operatively 3 times and compared with un-injured elbows at the same patient. Information was analyzed using t-test and SPSS soft ware. Results: Our findings showed that average range of movement at operated elbows in comparison with normal elbow at 3rd and 6th wks post operatively were meaningfully better in elbows operated through lateral approach (p=0.002) but at 12th week of postoperative the average range of motion at both groups did not have any meaning full statistical difference (p=0.4). Conclusion: The lateral approach does not have any superiority over posterior approach in post operative limitation of range of movement of elbows. However due to simplicity and lesser neurovascular complication posterior approach is better than lateral approach.

Introduction & Objective: Despite mild and self limited manifestation of rubella , involvement of fetus as a consequence of prenatal infection is very important and can lead to congenital rubella syndrome (Cs). The aim of this study was the evaluation of immunity rate against rubella virus in women who were in child bearing ages. Materials & Methods: This survey was performed with cooperation of health center on 248 cases of women who are offered for pre marriage serologic test and their titers of IgG antibody against rubella with Elisa method was measured. Results: Out of 248 specimens , 41 (16.5%) were non immune against rubella and 207 (83.5%) were immune. The frequency of immune serologic titer was highest in the age groupof 18-23 years and was lowest in the age group of 30-34 years. Of 138 cases that lived in the urban area, 121 cases (87.7%) were immune and 17 cases (12.3%) were non immune and out of 110 cases that lived in rural areas , 86 cases (78.2%) were immune and 24 cases (21.8%) were non immune. Education level of most women were graduated from high school (50.8%) , whereas the rate of illiterate women was least (1.6%). In this study nobody had a history of vaccination against rubella and 16 cases (6.5%) had a history of rubella infection. Conclusion: On the basis of this study 83.5% of subjects in studied group were immune against rubella and 16.5% were non-immune. This study showed that women in child bearing ages should be checked for rubella and vaccinated against it, if they are non immune.

Background: α-globin is encoded by two adjacent genes, αl and α2. Evidence suggests that these genes are not expressed equally and that the α2-globin gene encodes the majority of α-globin. This finding predicts that a thalassemic mutation of the α2-globin gene would result in a more severe loss of α-chain synthesis than a similar mutation in the αl-globin gene. Objectives: In the present study we described a novel non-deletion α-thalassemia defect in the 5'UTR region of the α2-globin gene. Materials and Methods: For molecular analysis, genomic DNA was isolated from peripheral blood cells by a salting out procedure. The common alpha deletion mutations were ruled out using the published primers and conditions. The amplification of the entire β and α1 globin genes was also carried out and their DNA was sequenced. No mutation was detected. Results: The mutation under study was located on an AP-1 transcription factor binding site and inherited in two unrelated Iranian families with hypochromic microcytic anemia. Conclusions: The patients in this study had moderate microcytosis and hypochromia without hemolysis, jaundice and splenomegaly. Molecular analysis in these patients revealed a non-deletion type of mutation in the promoter region, which is highly consistent with findings of other studies.

DNA is the most critical target of ionizing radiation when interact with cells. Several molecular studies have demonstrated modifications in expression levels of genes involved in the processes of signal transduction, cell cycle control, DNA repair and apoptosis following to exposure to ionizing radiation. The apoptosis intrinsic pathway is the main pathway that leads to apoptosis in response to DNA damage. The latter is responsible to regulate the release of mitochondrial proteins, including cytochrome-c (cytc). The aim of this study was to evaluate role of low-doses of gamma radiation on the apoptotic genes expression in human peripheral blood lymphocytes. Mononuclear cells were isolated from whole blood samples. They were exposed in culture to different doses from 2 to 10 cGy by gamma rays from a cobalt-60 source. Two apoptotic genes; BAX (pro-apoptotic) and Bcl-2 (antiapoptotic) were examined by relative quantitative Real-Time PCR for expression level, 4 and 24 hours following to irradiation. The study revealed, low doses of gamma radiation induced down-regulation for BAX gene and up-regulation for Bcl-2 gene. The result of present study has showed that low doses of gamma radiation could increase Bcl-2/BAX ratio and radio-resistance. These findings suggest that the genotoxic effects of low doses of gamma radiation may be due to adaptive response and a reduction of apoptosis.

Introduction Radioadaptive response (RAR) describes the phenomenan where low dose (called the ‘priming dose’) of ionizing radiation (IR) reduces harmful effects of subsequent higherdoses of IR (called the ‘challenge dose’). Purpose The aim of this study was to investigate the role of immune system genes in the adaptive response induced by low-dose of ionizing radiation. Materials and methods Mice were exposed to γ-rays from a 60Co source, to a series of priming and challenge doses at 31 mGy/min and 449 mGy/min respectively. Challenge dose was delivered 24 h following to priming dose. Expression level of two genes; IFN-γ IL-4 were examined by relative quantitative real-time polymerase chain reaction (RT-PCR) in 24 h after exposure. The non-parametric two independent samples T-test were performed to compare mean of gene expression level. Results The results of this study showed that the gene expression of both IL-4 and IFN-γ values significantly reduced after receiving high doses (P Conclusion These results are evident for that ionizing radiation may play a role in Th1 and Th2 cytokine expression immune response shift of Th1 cells toward Th2 after low and high dose radiation. Adaptive response to ionizing radiation induced by low dose of gamma ray can reduce the harmful effect of the radiation. Disclosure There is not any relationship that might lead to a conflict of interest. Mashhad University of Medical Sciences (MUMS) has financially supported this work.

Introduction While the widespread application of ionizing radiation in diagnostic and therapeutic medical procedures is unavoidable, Effects of low doses of ionizing radiation LDIR (low doses of ionizing radiation) are not quite obvious. Moreover, it has been showed that LDIR could affect our immune system. Purpose The aim of this study was to appraise the effects of LDIR on the inflammation genes expression levels of the immune system. Materials and Methods Balb/C mice were exposed to 20, 50 and 100 mGy WBI by gamma rays from a Cobalt-60 source. Lymphocytes of their spleen were extracted 24 h after exposing the animal for gene expression analysis. IL-4, IFN- γ and TGF- β expression levels were examined by relative quantitative real-time PCR and IFN- γ /IL-4 ratio was evaluated. To compare means values of gene expression the independent samples T-test was performed. Results The results of this study are evident that low doses of gamma radiation can induce changes on the expression level of the investigated genes and IFN-/IL-4 ratio in Balb/C spleen lymphocytes. A significant reduction of IL-4, IFN- γ and TGF- β genes and an increase of IFN- γ /IL-4 ratio has been induced in the group with 20 mGy of LDIR, while IFN- γ /IL-4 ratio was not changed following to 50 and 100 mGy of gamma irradiation. Conclusion Our result revealed that 20 mGy dose of gamma radiation can activate protection mechanisms as apoptosis and therefore cause the reduction of investigated genes and immune response shifting to Th1 and thereupon humoral immunity. However no shift to immune response has been observed in the groups which have received doses of 50 and 100 mGy. These results may be of importance to radiation workers and autoimmune patients. Disclosure There is not any relationship that might lead to a conflict of interest. Mashhad University of Medical Sciences (MUMS) has financially supported this work.

Introduction Radiation induced bystander effect (RIBE) is dependent to several parameters including total dose, dose rate, radiation quality, tissue type and volume of tissue irradiated in radiotherapy. Purpose The present study was designed to assess uncertainties in high dose RIBE. Materials and methods In this study, we used QU-DB and MRC5 cell lines. One hour following irradiation the medium transfer technique was used to induce bystander effect. Three end point was used in this study are MTT assay (to evaluate percentage of survival), colony assay (to evaluate survival fraction) and MN assay (for assessing chromosome aberrations). Results RIBE in both MN and survival fractions was decreased in doses higher than 4 Gy in lung tumoral cell line. After these two tests, we ensured that bystander effect has actually decreased at doses above 4 Gy. In other words high doses of ionizing radiation can produce a “negative feedback”. We did the dilution assay to evaluate for finding the main reason of RIBE reduction. In this test, by reducing the dilution of transferred media, the bystander effect (MN formation) was recreated. Conclusions This observation verified the negative feedback theory and reject activation of repair systems by more biological signals induced in target cells (as another theory). According to our results and because the dose range we used in the present study are as same as doses used in high dose radiotherapy techniques (e.g. Radiosurgery, brachytherapy etc.), we concluded it is promising that normal tissues can be preserved during high dose radiotherapy from dead signals generated by irradiated tumors. Disclosure There is not any relationship that might lead to a conflict of interest. Mashhad University of Medical Sciences (MUMS) has financially supported this work.

Lymphocytes have demonstrated complex molecular responses to induced stress by ionizing radiation. Many of these reactions are mediated through modifications in gene expressions, including the genes involved in apoptosis. The primary aim of this study was to assess the effects of low doses of ionizing radiation on the apoptotic genes, expression levels. The secondary goal was to estimate the time-effect on the modified gene expression caused by low doses of ionizing radiation. Mononuclear cells in culture were exposed to various dose values ranged from 20 to 100 mGy by gamma rays from a Cobalt-60 source. Samples were taken for gene expression analysis at hours 4, 24, 48, 72, and 168 following to exposure. Expression level of two apoptotic genes; BAX (pro-apoptotic) and Bcl-2 (anti-apoptotic) were examined by relative quantitative real-time polymerase chain reaction (PCR), at different time intervals. Radio-sensitivity of peripheral blood mononucleated cells (PBMCs) was measured by the Bcl-2/BAX ratio (as a predictive marker for radio-sensitivity). The non-parametric two independent samples Mann–Whitney U-test were performed to compare means of gene expression. The results of this study revealed that low doses of gamma radiation can induce early down-regulation of the BAX gene of freshly isolated human PBMCs; however, these changes were restored to near normal levels after 168 hours. In most cases, expression of the Bcl-2 anti-apoptotic gene was up-regulated. Four hours following to exposure to low doses of gamma radiation, apoptotic gene expression is modified, this is manifested as adaptive response. Modification of these gene expressions seems to be a principle pathway in the early radioresistance response. In our study, we found that these changes were temporary and faded completely within a week.

384 mothers out of the mothers dwelling in Kabudrahang district and Nozheh Airforce Station who had, at last, one infant under 24 months of age were selected in the study. Of these, 196 cases were from urban and 188 cases from rural regions. The results showed that 55% of the mothers had breastfed their infants for more than 12 months. Statistical evaluations showed that the duration of breast feeding tend to be associated with mother’s background characteristics such as education, age and their living in rural or urban regions.