Bystander Response Following High-Dose X-irradiation; Time-dependent Nature of GammaH2AX Foci and Cell Death Consequences.

Background: The paradigm shifts in target theory could be defined as the radiation-triggered bystander response in which the radiation deleterious effects occurred in the adjacent cells. Objective: This study aims to assess bystander response in terms of DNA damage and their possible cell death consequences following high-dose radiotherapy. Temporal characteristics of gH2AX foci as a manifestation of DNA damage were also evaluated. Material and Methods: In this experimental study, bystander response was investigated in human carcinoma cells of HeLa and HN5, neighboring those that received high doses. Medium transfer was performed from 10 Gy-irradiated donors to 1.5 Gy-irradiated recipients. GammaH2AX foci, clonogenic and apoptosis assays were investigated. The gH2AX foci time-point study was implemented 1, 4, and 24 h after the medium exchange. Results: DNA damage was enhanced in HeLa and HN5 bystander cells with the ratio of 1.27 and 1.72, respectively, which terminated in more than two-fold clonogenic survival decrease, along with gradual apoptosis increase. GammH2AX foci temporal characterization revealed maximum foci scoring at the 1 h time-point in HeLa, and also 4 h in HN5, which remained even 24 h after the medium sharing in higher level than the control group. Conclusion: The time-dependent nature of bystander-induced gH2AX foci as a DNA damage surrogate marker was highlighted with the persistent foci at 24 h. considering an outcome of bystander-induced DNA damage, predominant role of clonogenic cell death was also elicited compared to apoptosis. Moreover, the role of high-dose bystander response observed in the current work clarified bystander potential implications in radiotherapy.

Evaluation of Capability and Relationship of Different Radiobiological Endpoints for Radiosensitivity Prediction in Human Tumor Cell Lines Compared with Clonogenic Survival.

Background: Establishing a predictive assay of radiosensitivity (as an appropriate, practical and cost-effective method) has been challenging. Objective: The purpose of this study is to evaluate the capability and relationship of various endpoints, including GammaH2AX, micronuclei; and apoptosis in determining the human tumor cell lines radiosensitivities compared with clonogenic survival. Material and Methods: In an experimental in-vitro study, the response of carcinoma cell lines of HN5 and HeLa to 2 Gy of 6 MV photon beam was investigated via various assays. Results: Survival fraction at 2 Gy (SF2) of HeLa and HN5 was indicated as 0.42 ± 0.06 and 0.5 ± 0.03 respectively, proposing more radioresistance of HN5. This finding was confirmed with "2 Gy apoptosis enhancement ratio" which was 1.77 and 1.42 in HeLa and HN5. The increased levels of DNA DSBs were observed after irradiation; significant in HeLa with enhancement rate of 19.24. The micronuclei formation followed an ascending trend post irradiation; but with the least difference between two cells. Although the relationship between micronuclei and clonogenic survival was moderate (R2 = 0.35), a good correlation was observed between apoptosis and clonogenic survival (R2 = 0.71). Conclusion: The results of studied endpoints agreed with the SF2, highlighting their capabilities in radiosensitivity prediction. In terms of the enhancement ratio, gammaH2AX foci scoring could be a valid indicator of radiosensitivity but not the exact surrogate marker of survival because no correlation was observed. Moreover, considering the chief determents comprising lack of time and money, the apoptotic induction might be an appropriate indicator with the best correlation coefficient.

The radioprotective effect of melatonin against radiation-induced DNA double-strand breaks in radiology.

OBJECTIVE: The objective of this study is to observe the effect of 100-mg melatonin in reducing the levels of double-strand breaks (DSB) induced by 10 mGy and 100 mGy X-ray in peripheral lymphocyte applying H2AX immunofluorescence microscopy and comparing the different efficacies of melatonin ingestion 1 and 2 h before irradiation. MATERIALS AND METHODS: Informed consent was obtained from five healthy males, nonathlete, and nonsmoking human volunteers aged between 25 and 35 years. Each volunteer was given a single oral dose of 100 mg melatonin at 9 a.m. Blood samples were collected in vacutainer tubes (without any preservative to separate the serum, and with heparin as an anticoagulant for separating leukocytes for in vitro exposure to gamma radiation) 5-10 min before then 1 and 2 h after melatonin ingestion. Afterward, each sample was subdivided into nonirradiated and irradiated groups (10 mGy and 100 mGy). After irradiation, lymphocytes of samples were separated. The isolated lymphocytes in each group were permeabilized for DSB assessment and stained against the phosphorylated histone variant γH2AX. RESULTS: Melatonin ingestion 1 and 2 h before irradiation caused a significant reduction in γH2AX foci. Results further indicate that the change in ingestion of melatonin from 1 to 2 h before exposure had no significant effect. In addition, melatonin administration showed no side effects. CONCLUSION: The present study showed that melatonin will prove effective in radioprotection against ionizing radiation (IR)-induced DNA damage in human lymphocytes. Our results suggest ingestion of 100-mg melatonin by patients before exposure to IR in radiology.

Enhanced response of radioresistant carcinoma cell line to heterogeneous dose distribution of grid; the role of high-dose bystander effect.

PURPOSE: The classical dogma that restricted the radiation effect to the directly irradiated cells has been challenged by the bystander effect. This off-target phenomenon which was manifested in adjacent cells via signaling of fully exposed cells might be involved in high-dose Grid therapy as well. Here, an in-vitro study was performed to examine the possible extent of carcinoma cells response to the inhomogeneous dose distribution of Grid irradiation in the context of the bystander effect. MATERIALS AND METHODS: Bystander effect was investigated in human carcinoma cell lines of HeLa and HN5 adjacent to those received high-dose Grid irradiation using 'medium transfer' and 'cell-to-cell contact' strategies. Based on the Grid peak-to-valley dose profile, medium transfer was exerted from 10 Gy uniformly exposed donors to 1.5 Gy uniformly irradiated recipients. Cell-contact bystander was evaluated after nonuniform dose distribution of 10 Gy Grid irradiation using cloning cylinders. GammaH2AX foci, micronucleus and clonogenic assays besides gene expression analysis were performed. RESULTS: Various parameters (ɑ/ß, D37, D50) extracted from survival curve which fitted to the Linear Quadratic model, verified more radioresistance of HN5. Survival fraction at 2 Gy (SF2) indicated as 0.42 ± 0.06 in HeLa and 0.5 ± 0.03 in HN5. The level of survival decrease, DNA damages and micronucleus of cells located in the Grid shielded areas (1.5 Gy cell-to-cell contact bystander cells) were significantly more than the values obtained from cells which were irradiated by merely uniform dose of 1.5 Gy. The gH2AX foci and micronuclei frequencies were enhanced in cell-contact bystander approximately more than 1.8 times. Relative expression of DNA damage repair pathway genes (Xrcc6 and H2afx) in bystander cells increased significantly. The most cell survival reduction (11.6 times) was revealed in the Grid bystander cells of radioresistant cell line (HN5). No statistically significant difference between 10 Gy uniform beam and Grid non-uniform beam was observed. CONCLUSIONS: Various endpoints confirmed an augmented response of cells in the valley dose region of the Grid block significantly (compared with the cells irradiated by identical dose of uniform beam), suggesting the role of high-dose bystander effect which was more pronounced in resistant carcinoma cell lines. These findings could provide a partial explanation for the Grid beneficial response seen in a number of pre-clinical and clinical studies.

Melatonin a Promising Candidate for DNA Double-Stranded Breaks Reduction in Patients Undergoing Abdomen-Pelvis Computed Tomography Examinations.

BACKGROUND AND OBJECTIVE: Cancer incidence is 24% higher in children and young adults exposed to Computed Tomography (CT) scans than those unexposed. Non-repairing of ionizing radiation-induced DNA Double-Strand Breaks (DSBs) can initiate carcinogenesis. In the present study, we aimed to investigate the radioprotective potential of melatonin against DSBs in peripheral blood lymphocytes of patients undergoing abdomen-pelvis CT examinations. METHODS: This double-blind, placebo-controlled clinical trial was conducted on thirty patients. These patients were divided into two groups; group one (control) patients who have undergone the CT examination received a single oral dose of placebo, while in group two, patients received a single oral dose of 100mg melatonin. In both the groups, blood samples were collected 5-10min before and 30 minutes after the CT examination. The lymphocytes from these samples were isolated and DSBs were analyzed using γH2AX immunofluorescence microscopy. RESULTS: Compared to the control group, the use of melatonin 1h before the CT examination caused a significant reduction in γH2AX-foci, indicating a reduction in DSBs. In addition, no side effect was observed in patients following 100mg melatonin administration. CONCLUSION: For the first time, this study has shown that melatonin has protective effects against radiationinduced genotoxicity in peripheral blood lymphocytes of patients undergoing abdomen-pelvis CT examinations. Therefore, melatonin can be considered as a promising candidate for reducing DSBs in patients undergoing abdomen-pelvis CT examinations.

Enhanced cytotoxic and genotoxic effects of gadolinium-doped ZnO nanoparticles on irradiated lung cancer cells at megavoltage radiation energies.

The purpose of this study was to investigate the radiation dose enhancement effects of gadolinium-doped zinc oxide nanoparticles (Gd-doped ZnO NPs) under the megavoltage (MV) X-ray irradiation. ZnO NPs have preferred photocatalytic properties under UV light for cancer killing. UV light has limited applications in cancer treatment and it is necessary to use X-ray photons with MV energies. In order to increase the absorption of radiation and also to enhance the imaging visualization capabilities of ZnO NPs, gadolinium (Gd) as a high atomic number element was selected for doping into the structure of ZnO NPs. Gd-doped ZnO NPs were synthesized by a chemical precipitation method and characterized by transmission electron microscopy, powder X-ray diffraction, ultraviolet-visible spectroscopy, and energy-dispersive X-ray techniques. Cellular uptake was assessed by TEM and inductively coupled plasma mass spectrometry. NPs cytotoxicity was analyzed by MTT assay and radiation dose enhancement was measured by clonogenic survival assay. Apoptosis induction, cell cycle progression, micronucleus formation and expression of DNA double-strand break repair genes of XRCC2 and XRCC4 were determined by flow cytometry, micronucleus assay, and quantitative real-time polymerase chain reaction. CT and MR imaging were used to analyze the image visualization capabilities of NPs. NPs characterization showed that highly pure crystalline Gd-doped ZnO NPs with a narrow size distribution and grain size of 9 nm were synthesized. Gd-doped ZnO NPs were distributed in the cells and showed dose-dependent toxicity. Combination of Gd-doped ZnO NPs with 6 MV X-rays induced dose-dependent radiosensitivity with sensitizer enhancement ratios (SER) of 1.47 and 1.61 for 10 and 20 µg/mL NPs concentrations. Cancer cells blocked in G1, apoptosis rates, and micronuclei formation was enhanced and inversely, the DNA repair efficiency was impaired by down regulation of the mRNA levels of XRCC2 and XRCC4 genes. Gd-doped ZnO NPs enhanced the contrasts of CT and MR images of cancer cells. Overall, the results of this study provide detailed biological insights on the dose enhancement of Gd-doped ZnO NPs at MV radiations, which would contribute to the further development of this potent theranostic platform for clinical applications.

Glucosamine Protects Rat Bone Marrow Cells Against Cisplatin-induced Genotoxicity and Cytotoxicity.

BACKGROUND AND OBJECTIVE: Glucosamine is a widely prescribed dietary supplement used in the treatment of osteoarthritis. In the present study, the chemoprotectant ability of glucosamine was evaluated against cisplatin-induced genotoxicity and cytotoxicity in rat bone marrow cells. METHODS: Glucosamine was orally administrated to rats at doses of 75 and 150 mg/kg body weight for seven consecutive days. On the seventh day, the rats were treated with a single injection of cisplatin (5 mg/kg, i.p.) at 1h after the last oral administration. The cisplatin antagonistic potential of glucosamine was assessed by micronucleus assay, Reactive Oxygen Species (ROS) level analysis, hematological analysis, and flow cytometry. RESULTS: Glucosamine administration to cisplatin-treated rats significantly decreased the frequencies of Micronucleated Polychromatic Erythrocytes (MnPCEs) and Micronucleated Normchromatic Erythrocytes (MnNCEs), and also increased PCE/(PCE+NCE) ratio in bone marrow cells. Furthermore, treatment of rats with glucosamine before cisplatin significantly inhibited apoptosis, necrosis and ROS generation in bone marrow cells, and also increased red blood cells count in peripheral blood. CONCLUSION: This study shows glucosamine to be a new effective chemoprotector against cisplatin-induced DNA damage and apoptosis in rat bone marrow cells. The results of this study may be helpful in reducing the harmful effects of cisplatin-based chemotherapy in the future.

CD40 Knocked Down Tolerogenic Dendritic Cells Decrease Diabetic Injury.

BACKGROUND: Type-1 diabetes (T1D) is an autoimmune disease in which T lymphocytes destroy insulin-producing ß-cells. Control of self-reactive T lymphocytes and recovery of diabetic injury is the end point of T1D. OBJECTIVE: To investigate generation of tolerogenic dendritic cells (tolDCs) as an innovative method of diabetes therapy. METHODS: Lentivirus vector production was achieved by GIPZ mouse CD40 shRNA, psPAX2 and pMD2G plasmids DNA. Purified bone marrow derived DCs were treated with CD40 shRNA, and expression of CD40 and mRNA level were evaluated by flow cytometry and Real-Time PCR, respectively. CD40 knock-down DCs were injected into STZ-induced diabetic mice. Blood glucose; glucose tolerance test and weight were analyzed in different groups. RESULTS: Mice treated with CD40 shRNA transfected DCs showed considerable differences in blood glucose, glucose tolerance, and weight compared to other groups. Also cytokine assays indicated an increase in IL-13 production in the CD40 shRNA group. CONCLUSION: In streptozotocin-induced diabetic mice model, administration of tolerogenic dendritic cells could improve diabetic parameters.

Dependence of micronuclei assay on the depth of absorbed dose.

AIM: The purpose of the present study is to investigate the dependence of micronuclei response on the depth of absorbed dose. BACKGROUND: One of the most common cytogenetic methods used for radiation dosimetry is micronuclei (MN). Being less complex and faster than other methods are two remarkable advantages of the MN method which make it suitable for monitoring of population. In biological dosimetry based on the micronuclei method, the investigation into the dependence of response on the depth in which dose is absorbed is significant, though has received less attention so far. MATERIALS AND METHODS: Blood samples were poured in separate vials to be irradiated at different depths using a linear accelerator system. RESULTS: According to the results, MN, as a function of the absorbed dose, had the best fitness with the linear-quadratic model at all depths. Furthermore, the results showed the dependence of MN response on the depth of absorbed dose. For doses up to 2 Gy, the maximum difference from the reference depth of 1.5 cm was related to the depth of 10 cm; however, by increasing the absorbed dose, the response associated with the depth of 20 cm showed the maximum deviation from the reference depth. CONCLUSIONS: Consequently, it is necessary to apply a correction factor to the biological dosimetry. The correction factor is dependent on the depth and the absorbed dose.

Radioprotective effect of Zamzam (alkaline) water: A cytogenetic study.

BACKGROUND: Radioprotectors are useful compounds to reduce radiation toxicity of normal cells. Many natural radioprotectors have antioxidant power and display fewer toxicity and side effects than the chemical ones. Alkaline waters such as Zamzam have antioxidant power potentially. This study aimed to investigate the radioprotective effect of Zamzam water in mice bone marrow exposed to gamma radiation by micronuclei test. METHOD: Five study groups including control group which was fed by ordinary water, the second group was fed by Zamzam water, and radiation groups were received 2Gy gamma with ordinary and Zamzam water for 10 days and another for 20 days. The frequency of micronuclei and polychromatic erythrocytes to normochromatic erythrocytes ratio were calculated by micronuclei test. RESULT: In the absence of radiation, no significant difference was found between Zamzam group and control in the number of micronuclei in normochromatic erythrocytes, micronuclei in polychromatic erythrocytes, and the polychromatic erythrocyte to polychromatic erythrocyte plus normochromatic erythrocyte ratio. But all of these indices were significantly different between irradiated and non-irradiated groups. The frequency of micronuclei in polychromatic erythrocytes was not significantly different between 10 and 20 days Zamzam irradiated groups, but the reduction in micronuclei in normochromatic erythrocytes and an increase in the polychromatic erythrocyte to polychromatic erythrocyte plus normochromatic erythrocyte ratio compared to ordinary water were seen in 20 days Zamzam group. Dose reduction factor was 1.36 and 2 for Zamzam water groups of 10 days and 20 days, respectively. CONCLUSION: The results demonstrated that Zamzam alkaline water could reduce clastogenic and cytotoxic effects of gamma irradiation.

The radioprotective effect of metformin against cytotoxicity and genotoxicity induced by ionizing radiation in cultured human blood lymphocytes.

Metformin is a widely prescribed drug used in the treatment of patients with type 2 diabetes. In this study, the radioprotective effect of metformin was investigated against cytotoxicity and genotoxicity induced by ionizing radiation (IR) in human peripheral blood lymphocytes. Human lymphocytes were treated with metformin at concentrations 10 and 50µM for 2h and irradiated with 6MV X-rays. The radiation antagonistic potential of metformin was assessed by MTT [3-(4,5-dimethyl-2-thiaozolyl)-2,5-diphenyl-2H tetrazolium bromide] assay, chromosomal aberration (CA) analysis, cytokinesis blocked micronucleus (CBMN) assay, and flow cytometry. Observations demonstrated a radiation-dose-dependent decrease in the percentage of cell viability after 24h. It was found that pretreatment with metformin (10 and 50µM) increased the percentage of cell viability. A highly significant dose modifying factor (DMF) 1.35 and 1.42 was observed for 10 and 50µM metformin, respectively. Metformin (10 and 50µM) pretreatment significantly decreased the frequency of dicentrics (DCs), acentric fragments (AFs), rings (RIs), micronuclei (MN), and nucleoplasmic bridges (NPBs) in irradiated human peripheral blood lymphocytes. Also, treatment with metformin (10 and 50µM) without irradiation did not increase the number of MN, NPBs, DCs, AFs, RIs, and did not show a cytostatic effect in the human peripheral blood lymphocytes. On the other hand, metformin treatment (10 and 50µM) 2h prior to irradiation significantly reduced X-radiation-induced apoptotic incidence in human lymphocytes. The present study demonstrates metformin to be an effective radioprotector against DNA damage and apoptosis induced by IR in human lymphocytes. These data have an important application for the protection of lymphocytes from the genetic damage and side-effects induced by radiotherapy in cancer patients.

Collagen-chitosan 3-D nano-scaffolds effects on macrophage phagocytosis and pro-inflammatory cytokine release.

Macrophages are effector cells in the innate and adaptive immune systems and in situ exist within three-dimensional (3-D) microenvironments. As there has been an increase in interest in the use of 3-D scaffolds to mimic natural microenvironments in vitro, this study examined the impact on cultured mice peritoneal macrophages using standard 2-D plates as compared to 3-D collagen-chitosan scaffolds. Here, 2-D and 3-D cultured macrophages were evaluated for responses to lipopolysaccharide (LPS), dexamethasone (Dex), BSA (bovine serum albumin), safranal (herbal component isolated from safranal [Saf]) and Alyssum homolocarpum mucilage (A. muc: mixed herbal components). After treatments, cultured macrophages were evaluated for viability, phagocytic activity and release of tumor necrosis factor (TNF)-α and interleukin (IL)-1ß pro-inflammatory cytokines. Comparison of 2-D vs 3-D cultures showed that use of either system - with or without any exogenous agent - had no effect on cell viability. In the case of cell function, macrophages cultured on scaffolds had increases in phagocytic activity relative to that by cells on 2-D plates. In general, the test herbal components Saf and A. muc. had more impact than any of the other exogenous agents on nanoparticle uptake. With respect to production of TNFα and IL-1ß, compared to the 2-D cells, scaffold cells tended to have significantly different levels of production of each cytokine, with the effect varying (higher or lower) depending on the test agent used. However, unlike with particle uptake, here, while Saf and A. muc. led to significantly greater levels of cytokine formation by the 3-D culture cells vs that by the 2-D plate cells, there was no net effect (stimulatory) vs control cultures. These results illustrated that collagen-chitosan scaffolds could provide a suitable 3-D microenvironment for macrophage phagocytosis and could also impact on the formation of pro-inflammatory cytokines.

Prophylactic role of some plants and phytochemicals against radio-genotoxicity in human lymphocytes.

Genotoxicity in lymphocytes of cancer patients undergoing radiotherapy can lead to lymphocytopenia. Lymphocytopenia induced by radiotherapy is one of the most unfavorable prognostic biological markers in cancer patients, since it has been accepted to be associated with poor prognosis in terms of both survival time and response to cancer therapy. Therefore, reduction in lymphocytopenia may increase treatment efficiency. Research endeavors with synthetic radioprotectors in the past have met with little success primarily due to toxicity-related problems. These disadvantages have led to interest on the use of some plants and phytochemicals as radioprotector. The aim of this paper is to review protective role of some plants and phytochemicals against genotoxicity-induced by ionizing radiation in human blood lymphocytes. Therefore, current review may help the future researches to decrease lymphocytopenia in radiotherapeutic clinical trials.

Tumor cell culture on collagen-chitosan scaffolds as three-dimensional tumor model: A suitable model for tumor studies.

Tumor cells naturally live in three-dimensional (3D) microenvironments, while common laboratory tests and evaluations are done in two-dimensional (2D) plates. This study examined the impact of cultured 4T1 cancer cells in a 3D collagen-chitosan scaffold compared with 2D plate cultures. Collagen-chitosan scaffolds were provided and passed confirmatory tests. 4T1 tumor cells were cultured on scaffolds and then tumor cells growth rate, resistance to X-ray radiation, and cyclophosphamide as a chemotherapy drug were analyzed. Furthermore, 4T1 cells were extracted from the scaffold model and were injected into the mice. Tumor growth rate, survival rate, and systemic immune responses were evaluated. Our results showed that 4T1 cells infiltrated the scaffolds pores and constructed a 3D microenvironment. Furthermore, 3D cultured tumor cells showed a slower proliferation rate, increased levels of survival to the X-ray irradiation, and enhanced resistance to chemotherapy drugs in comparison with 2D plate cultures. Transfer of extracted cells to the mice caused enhanced tumor volume and decreased life span. This study indicated that collagen-chitosan nanoscaffolds provide a suitable model of tumor that would be appropriate for tumor studies.

Arginine increases genotoxicity induced by methyl methanesulfonate in human lymphocytes.

Nitric oxide (NO) is a free radical that is produced in cells from L-arginine. NO is involved in the physiological control of different tissues, but it can act as a toxic mediator in the cells. In this study we investigated the effect of L-arginine on the genotoxicity induced by methyl methanesulfonate (MMS) in human lymphocytes. Blood was treated with N(G)-nitro-L-arginine methyl ester (L-NAME) as an inhibitor of nitric oxide synthase for finding out the role of NO in this effect. Human whole blood was treated with L-arginine (50, 100 and 250 µM) and/or L-NAME, then it was treated in vitro with MMS after 24 h of culture. The lymphocytes were stimulated by phytohemagglutinin to find out the micronuclei in cytokinesis-blocked binucleated cells. DNA fragmentation of lymphocytes was detected by using a fluorescence microscope after propidium iodide staining. These data showed that arginine increased the frequency of MMS-induced micronuclei in lymphocytes. However, the genotoxicity was decreased by using L-NAME. Arginine and L-NAME have not shown any DNA damage in cultured human lymphocytes. In conclusion, addition of L-arginine to MMS as an alkylating agent caused an increase of DNA damage in human lymphocytes. This enhancement of genotoxicity was reduced by NAME as NO inhibitor. It is thus cleared that an increase of DNA damage by arginine and MMS is related to NO production.

Hesperidin inhibits cyclophosphamide-induced tumor growth delay in mice.

Hesperidin is a natural compound that has chemoprotective effects in tumor cell lines and protective effects against hematotoxicity induced by cyclophosphamide. The aim of this study was to evaluate the effect of hesperidin on the antitumor effect of cyclophosphamide in tumor-bearing mice. Administration of hesperidin reduced the leukopenia induced by cyclophosphamide in normal mice. White blood cell counts were increased in mice treated with hesperidin at a dose 200 mg/kg prior to cyclophosphamide injection. This significant protective effect was observed at 4 and 7 days after cyclophosphamide injection. Coadministration of hesperidin with cyclophosphamide in colon carcinoma (CT-26)-bearing mice was found to significantly inhibit cyclophosphamide-induced tumor growth delay. Tumor-bearing mice treated with hesperidin had increased tumor development compared with control animals that did not receive any treatment. These results show that hesperidin interacts with cyclophosphamide to inhibit its antitumor effect. In this study, estrogen receptor was negative for the development of CT-26 tumor. These results imply that fruits containing hesperidin, such as citrus, might have side effects on the efficacy of cyclophosphamide in the treatment of patients with colon cancer.

The radioprotective effect of Zataria multiflora against genotoxicity induced by γ irradiation in human blood lymphocytes.

The radioprotective effect of hydroalcholic Zataria multiflora (Avishan-e shirazi) extract was investigated against genotoxicity induced by γ irradiation in human lymphocytes. Peripheral blood samples were collected from human volunteers and incubated with Z. multiflora extract at different concentrations (5, 10, and 50 µg/mL) for 1 hour. At each dose point, the whole blood was exposed in vitro to 150 cGy of cobalt-60 γ irradiation, and then the lymphocytes were cultured with mitogenic stimulation to determine number of the micronuclei in cytokinesis-blocked binucleated cells. The treatment of lymphocytes with extract showed a significant decrease in the incidence of micronuclei binucleated cells, compared with similarly irradiated lymphocytes without extract against γ irradiation. The maximum protection and decrease in frequency of micronuclei was observed at 50 µg/mL of Zataria extract by 32% reduction. High-performance liquid chromatography analysis of extract showed that it contains high amounts of thymol. Zataria extract exhibited concentration-dependent radical-scavenging activity on 1,1-diphenyl-2-picryl hydrazyl free radicals. These data have an important application for the protection of human lymphocyte from the genetic damage and side-effects induced by γ irradiation in personnel exposed to radiation.

Protective effects of hesperidin against genotoxicity induced by (99m)Tc-MIBI in human cultured lymphocyte cells.

INTRODUCTION: Radiopharmaceuticals have been widely used as nuclear tracers for myocardial perfusion imaging. The purpose of this study was to investigate the radioprotective effects of hesperidin as a flavonoid which protects against the genotoxic effects of (99m)Tc-MIBI in human cultured lymphocytes. METHODS: Whole blood samples from human volunteers were incubated with hesperidin at doses of 10, 50 and 100 micromol. After 1 h of incubation, the lymphocytes were incubated with (99m)Tc-MIBI (200 microCi/2 ml) for 3 h. The lymphocyte cultures were then mitogenically stimulated to allow for evaluation of the number of micronuclei in cytokinesis-blocked binucleated cells. RESULTS: Incubation of lymphocytes with (99m)Tc-MIBI at this high dose induces additional genotoxicity and shown by increases in micronuclei frequency in human lymphocytes. Hesperidin at these doses significantly reduced the micronuclei frequency in cultured lymphocytes. The maximum protective effect and greatest decrease in micronuclei frequency occurred when cultures were incubated with a 100-micromol dose of 65% hesperidin. CONCLUSION: This study has important implications for patients undergoing nuclear medicine procedures. The results indicate a protective role for hesperidin against the genetic damage and side effects induced by radiopharmaceutical administration.

Radioprotective effects of Daflon against genotoxicity induced by gamma irradiation in human cultured lymphocytes.

The ability of Daflon to protect against genotoxicity induced by gamma irradiation has been investigated in vivo and in vitro in cultured lymphocytes from healthy human volunteers. Peripheral human blood samples were collected predose (10 min before) and 1, 2, and 3 hr after a single oral ingestion of 1000 mg of Daflon. At each time point, whole blood was exposed in vitro to 150 cGy of cobalt-60 gamma rays, and then the lymphocytes were cultured with mitogenic stimulation to determine the micronuclei in cytokinesis-blocked binucleated cells. For each volunteer, the results showed a significant increase in the incidence of micronuclei after exposure to gamma irradiation as compared to control unexposed samples. As early as 1 hr after Daflon administration, a significant decrease in the incidence of micronuclei was observed in comparison with similarly irradiated lymphocytes collected before administration. The maximum protection was reached 1 hr after administration of Daflon with a significant decrease in the frequency of micronuclei of 40%. These findings suggest the possible application of Daflon for the protection of human lymphocytes from the genetic damage and side effects induced by gamma irradiation.

Radioprotective effects of hesperidin against genotoxicity induced by gamma-irradiation in human lymphocytes.

The radioprotective effect of hesperidin against genotoxicity induced by gamma-irradiation has been investigated in vivo/in vitro in cultured blood lymphocytes from human volunteers. Peripheral blood samples were collected at 0 (10 min before) and at 1, 2 and 3 h after a single oral ingestion of 250 mg hesperidin. At each time point, the whole blood was exposed in vitro to 150 cGy of (60)Co gamma-irradiation and then the lymphocytes were cultured with mitogenic stimulation to determine the micronuclei in cytokinesis-blocked binucleated cells. For each volunteer, the results showed a significant increase in the incidence of micronuclei after exposure of cells to gamma-irradiation as compared to control samples. The lymphocytes in the blood samples collected at 1 h after hesperidin ingestion and exposed in vitro to gamma-rays exhibited a significant decrease in the incidence of micronuclei, compared with similarly irradiated lymphocytes from blood samples collected at 0 h. The maximum protection and decrease in frequency of micronuclei (33%) was observed at 1 h after ingestion of hesperidin. These data have important application for the protection of human lymphocytes from the genetic damage and side effects induced by gamma-irradiation in patients undergoing radiotherapy.