Gy Γ-rays Research Articles

The Antioxidant Flavonoids, Orientin and Vicenin Enhance Repair of Radiation-Induced Damage

A B S T R A C T Orientin (Ot) and vicenin (Vc), two water soluble flavonoids isolated from the Indian Holy Basil, are potent radioprotectants, but the mechanisms of protection are not fully understood. In the present study, we investigated the effects of these flavonoids as antioxidants in chemical systems and plasmid DNA and radioprotectants in bacterial and mammalian cells. The radical scavenging activities of Ot and Vc were assessed in two chemical systems, dipehnylpicrylhydrazyl (DPPH) and 2,2´-azino-bis(3-thylbenz-thiazoline-6sulfonic acid) (ABTS) by estimating absorbance at 517 and 734 nm, respectively. Protection by the flavonoids against H 2 O 2 (30 mM) damage to plasmid pGEM7Zf was assessed by DNA electrophoresis. Effect of flavonoid pre-treatment on survival of irradiated (30-150 Gy γ-rays) repair proficient (AB1157) and repair deficient (MD2130) E.coli cells was assayed. Furthermore, induction and repair of DNA damage to 4 Gy irradiated mouse splenocytes was analyzed using the comet assay. Ot and Vc significantly scavenged DPPH and ABTS. Both flavonoids protected plasmid pGEM-7Zf in the nicked circular form following H 2 O 2 treatment. Pretreatment with 200 µM of either flavonoid significantly increased clonogenic survival of repair proficient cells at all radiation (RT) doses; in repair deficient strain, protection was significant at the lower RT doses (30 and 50 Gy, p<0.01). Ot and Vc significantly reduced 4 Gy-induced DNA damage and allowed for faster repair of ex-vivo irradiated mouse splenocytes.

Single administration of p2TA (AB103), a CD28 antagonist peptide, prevents inflammatory and thrombotic reactions and protects against gastrointestinal injury in total-body irradiated mice.

The goal of this study was to elucidate the action of the CD28 mimetic peptide p2TA (AB103) that attenuates an excessive inflammatory response in mitigating radiation-induced inflammatory injuries. BALB/c and A/J mice were divided into four groups: Control (C), Peptide (P; 5 mg/kg of p2TA peptide), Radiation (R; total body irradiation with 8 Gy γ-rays), and Radiation + Peptide (RP; irradiation followed by p2TA peptide 24 h later). Gastrointestinal tissue damage was evaluated by analysis of jejunum histopathology and immunohistochemistry for cell proliferation (Cyclin D1) and inflammation (COX-2) markers, as well as the presence of macrophages (F4/80). Pro-inflammatory cytokines IL-6 and KC as well as fibrinogen were quantified in plasma samples obtained from the same mice. Our results demonstrated that administration of p2TA peptide significantly reduced the irradiation-induced increase of IL-6 and fibrinogen in plasma 7 days after exposure. Seven days after total body irradiation with 8 Gy of gamma rays numbers of intestinal crypt cells were reduced and villi were shorter in irradiated animals compared to the controls. The p2TA peptide delivery 24 h after irradiation led to improved morphology of villi and crypts, increased Cyclin D1 expression, decreased COX-2 staining and decreased numbers of macrophages in small intestine of irradiated mice. Our study suggests that attenuation of CD28 signaling is a promising therapeutic approach for mitigation of radiation-induced tissue injury.

Dose-effect of ionizing radiation-induced PIG3 gene expression alteration in human lymphoblastoid AHH-1 cells and human peripheral blood lymphocytes

Purpose: To identify new ionizing radiation (IR)-sensitive genes and observe the dose-effect of gene expression alteration (GEA) induced by IR.Materials and methods: Microarray was used to screen the differentially expressed genes in human lymphoblastoid cells (AHH-1) using three doses of 60Co γ-rays (0.5–8 Gy at 1 Gy/min). Given that p53-inducible gene 3 (PIG3) was consistently upregulated, the GEA of PIG3 in AHH-1 cells and human peripheral blood lymphocytes (HPBL) induced by γ-rays (1 Gy/min) was measured at messenger RNA (mRNA) and protein levels. The GEA of PIG3 in AHH-1 cells exposed to neutron radiation (californium-252, 0.073 Gy/min) was also quantified.Results: PIG3 was one of the seven differentially expressed genes found in the microarray analysis. The PIG3 mRNA and protein levels in AHH-1 cells were significantly increased from 1–10 Gy of γ-rays 8–72 h or 8–168 h after exposure, respectively. The enhancement was also observed in AHH-1 cells from 0.4–1.6 Gy of neutrons 48 h post-irradiation. The PIG3 mRNA levels (mRNA copy numbers) in HPBL were significantly increased from 1–8 Gy of γ-rays within 4–24 h post-irradiation, but the highest increase in signal-to-noise responsiveness is approximately two-fold, which was less than that of AHH-1 (approximately 20-fold).Conclusions: IR can upregulate the PIG3 gene expression in AHH-1 and HPBL in the early phase after exposure; however, the IR induced expression levels of PIG3 are greater in AHH-1 than HPBL.

Low-dose radiation from 18F-FDG PET does not increase cancer frequency or shorten latency but reduces kidney disease in cancer-prone Trp53+/- mice.

There is considerable interest in the health effects associated with low-level radiation exposure from medical imaging procedures. Concerns in the medical community that increased radiation exposure from imaging procedures may increase cancer risk among patients are confounded by research showing that low-dose radiation exposure can extend lifespan by increasing the latency period of some types of cancer. The most commonly used radiopharmaceutical for positron emission tomography (PET) scans is 2-[(18)F] fluoro-2-deoxy-d-glucose ((18)F-FDG), which exposes tissue to a low-dose, mixed radiation quality: 634 keV β+ and 511 keV γ-rays. The goal of this research was to investigate how modification of cancer risk associated with exposure to low-dose ionising radiation in cancer-prone Trp53+/- mice is influenced by radiation quality from PET. At 7-8 weeks of age, Trp53+/- female mice were exposed to one of five treatments: 0 Gy, 10 mGy γ-rays, 10 mGy (18)F-FDG, 4 Gy γ-rays, 10 mGy (18)F-FDG + 4 Gy γ-rays (n > 185 per group). The large 4-Gy radiation dose significantly reduced the lifespan by shortening the latency period of cancer and significantly increasing the number of mice with malignancies, compared with unirradiated controls. The 10 mGy γ-rays and 10 mGy PET doses did not significantly modify the frequency or latency period of cancer relative to unirradiated mice. Similarly, the PET scan administered prior to a large 4-Gy dose did not significantly modify the latency or frequency of cancer relative to mice receiving a dose of only 4 Gy. The relative biological effectiveness of radiation quality from (18)F-FDG, with respect to malignancy, is approximately 1. However; when non-cancer endpoints were studied, it was found that the 10-mGy PET group had a significant reduction in kidney lesions (P < 0.021), indicating that a higher absorbed dose (20 ± 0.13 mGy), relative to the whole-body average, which occurs in specific tissues, may not be detrimental.

Characteristics of nucleoplasmic bridges induced by 60Co γ-rays in human peripheral blood lymphocytes

Few studies have shown that the yields of ionising-radiation-induced nucleoplasmic bridges (NPBs) in human cells are dose dependent. However, a dose-response curve between the NPB frequency and the absorbed dose of ionising radiation has not yet been established. This study aimed to investigate NPB frequencies in human peripheral blood lymphocytes induced by cobalt-60 (60Co) γ-rays and to establish a dose-response curve. Human peripheral blood samples were collected from three healthy males, and some of these samples were irradiated with 0-6 Gy 60Co γ-rays. A cytokinesis-block micronucleus cytome assay was then carried out to analyse NPBs and micronuclei (MN) in binucleated cells. The remaining blood samples were irradiated with 0, 2 and 5 Gy of γ-rays, and unstable chromosome aberrations (dicentric chromosome, ring chromosome and acentric chromosome fragment) were analysed. The correlation between NPBs and dicentric plus ring chromosome (dic+r) induced by the same γ-ray dose was also analysed. Results showed that the NPB yields among the three subjects at each dose level were not significantly different. NPBs in binucleated cells at all γ-ray doses conformed to Poisson distribution. The dose-response curve of the γ-ray-induced NPB frequencies followed the linear-quadratic model y = (1.39×10-3)x 2 + (4.94×10-3)x. A positive correlation was observed between the frequencies of NPB and dic+r, as well as between the frequencies of MN and acentric fragments. Therefore, NPB is an important biomarker of early chromosome damage event induced by ionising radiation.

Thermoluminescence characteristics of Na3 SO4 Cl:X (X=Ce, Dy, Mn) phosphor

In the present paper Na3SO4Cl:Ce, Na3SO4Cl:Dy, Na3SO4Cl:Mn, of Na3SO4Cl:Ce, Dy and Na3SO4Cl:Ce, Mn phosphor were synthesized by the wet chemical method. Thermoluminescence (TL) characteristics of Na3SO4Cl:Ce, Na3SO4Cl:Dy, Na3SO4Cl:Mn, Na3SO4Cl:Ce, Dy and Na3SO4Cl:Ce, Mn phosphors were studied for 5 Gy γ-ray dose. In TL glow curve, two peaks have been observed at 129°C and 224°C for different concentrations of Ce and Dy, whereas Mn peaks at 212°C. The same host is also tried for Ce, Dy (peaks at 126, 219) and Ce, Mn (248°C). A significant single peak is observed in the case of Na3SO4Cl:Mn and Na3SO4Cl:Ce, Mn. This may be due to the effect of activators. It is found that intensity tends to be increase with increased concentrations of the activators. The TL glow curves of the phosphors have been recorded and irradiated at a rate of 0.39 kGy h−1 for 5 Gy γ-rays dose. It is also found that all the phosphors are less sensitive as compared with Thermoluminescence dosimetry-CaSO4: Dy for the same γ-rays dose. The paper discuses the preliminary TL characteristics and effect of γ-rays on Na3SO4Cl:Ce, Na3SO4Cl:Dy, Na3SO4Cl:Mn, Na3SO4Cl:Ce, Dy and Na3SO4Cl:Ce, Mn phosphors.

Investigation of switch from ATM to ATR signaling at the sites of DNA damage induced by low and high LET radiation

Upon induction of DNA damage by ionizing radiation (IR), members of the phosphatidylinositol 3-kinase-like kinase family of proteins namely ataxia-telangiectasia mutated (ATM), DNA-PKcs, and ATM- and Rad3-related (ATR) maintain genomic integrity by mounting DNA damage response (DDR). Recent reports suggest that activation of ATM and ATR are oppositely regulated by the length of single stranded overhangs generated during end processing by nucleases at the break sites. These stretches of single stranded overhangs hold the clue for the transition from ATM to ATR signaling at broken DNA ends. We investigated whether differential processing of breaks induced by low and high LET radiation augments the phenomenon of switching from ATM to ATR kinase and hence a concomitant NHEJ to HR transition at the sites of DNA damage. 82-6 human fibroblasts were irradiated with 1 or 2Gy of γ-rays and particle radiation of increasing LET in order to increase the complexity and variability of DNA double strand breaks (DSB) structures. The activation kinetics of ATM and ATR kinases along with their downstream substrates were determined utilizing Western blotting and immunofluorescence techniques. Our data provide evidence of a potential switch from ATM to ATR kinase signaling in cells treated with γ-rays at approximately 2h post irradiation, with induction and completion of resection denoted by Rad51 foci resolution kinetics and observed with a significant decline of phosphorylated ATR kinase 8h after IR. On the other hand, irradiation with high LET 600MeV/u (56)Fe (180keV/μm) and 170MeV/u (28)Si (99keV/μm) particles show a similar Rad51 foci decay kinetics, however, exhibiting prolonged resection, evident by the persistent phosphorylated ATM and ATR kinase until 24h post irradiation. This residual effect, however, was significantly reduced for 250MeV/u (16)O particles of moderate LET (25keV/μm) and absent for γ-rays. Hence, our results support the hypothesis that the transition from ATM to ATR signaling at DNA break sites is extended for longer periods of time, indicated by sustained resection due to the complex type of damage induced, a hallmark of high LET radiation, which may contribute to its increased biological effectiveness.

Induction and disappearance of γH2AX foci and formation of micronuclei after exposure of human lymphocytes to 60Co γ-rays and p(66)+ Be(40) neutrons

Purpose: To investigate both the formation of micronuclei (MN) and the induction and subsequent loss of phosphorylated histone H2AX foci (γH2AX foci) after in vitro exposure of human lymphocytes to either 60Co γ-rays or p(66)+ Be(40) neutrons.Materials and methods: MN dose response (DR) curves were obtained by exposing isolated lymphocytes of 10 different donors to doses ranging from 0–4 Gy γ-rays or 0–2 Gy neutrons. Also, γH2AX foci DR curves were obtained following exposure to doses ranging from 0–0.5 Gy of either γ-rays or neutrons. Foci kinetics for lymphocytes for a single donor exposed to 0.5 Gy γ-rays or neutrons were studied up to 24 hours post-irradiation.Results: Micronuclei yields following neutron exposure were consistently higher compared to that from 60Co γ-rays. All MN yields were over-dispersed compared to a Poisson distribution. Over-dispersion was higher after neutron irradiation for all doses > 0.1 Gy. Up to 4 hours post-irradiation lower yields of neutron-induced γH2AX foci were observed. Between 4 and 24 hours the numbers of foci from neutrons were consistently higher than that from γ-rays. The half-live of foci disappearance is only marginally longer for neutrons compared to that from γ-rays. Foci formations were more likely to be over-dispersed for neutron irradiations.Conclusion: Although neutrons are more effective to induce MN, the absolute number of induced γH2AX foci are less at first compared to γ-rays. With time neutron-induced foci are more persistent. These findings are helpful for using γH2AX foci in biodosimetry and to understand the repair of neutron-induced cellular damage.

Effect of low dose gamma rays on certain essential metals and oxidative stress in different rat organs

The present work aimed to determine the effect of low dose (0.03 Gy) γ-rays on certain essential metals namely Fe, Cu, Zn and Ca levels in various tissues (liver, kidney, testis, spleen, intestine, heart and brain) in rats. Also, lipid peroxidation as malondialdehyde (MDA) and metallothionein (MT) levels were measured in liver, kidney and testis. Rats were exposed to total dose of 0.03 Gy γ-rays along 12 h at a low dose rate (2.5 mGy/h). The results obtained manifested elevation in all essential metals studied in liver. All organs showed elevated Ca levels except that of brain with non-significant change in intestine. Decrease in Fe levels were observed in kidney, testis, intestine, heart and brain tissues with insignificant change in spleen tissue. Elevation in MDA in liver and kidney tissues was recorded and an inhibition in MT in liver, kidney and testis tissues was demonstrated. In conclusion, the previous essential metals tested are very sensitive to low dose (0.03 Gy) γ-rays. Such dose can induce alterations in the oxidative stress parameters under investigation.

Curcumin protection activities against γ-Rays-induced molecular and biochemical lesions

BackgroundCurcumin is a yellow-pigment phenolic compound used as a food spice and has a broad spectrum of antioxidant, anti-carcinogenic, anti-mutagenic and anti-inflammatory properties.MethodsRadio-protective efficacy of curcumin; diferuloylmethane (C21H20O6) was evaluated using molecular and biochemical assays in male mice after exposure to 3 Gy γ-rays. Curcumin was given at a dose of 400 μmol/ kg body weight via gastric tubes for 5 following days either pre-, post- or both pre- and post-exposure.ResultsThe incidence of aberrant cells and aberration types (mostly chromatids, breaks and fragments) was reduced with curcumin dosage as compared to irradiated group. Thiobarbituric acid reactive substances (TBARS), hydroperoxide (HP), xanthine oxidase (XO) and apoptotic markers (DNA- fragmentation and caspase-3 activation) were increased significantly, whereas levels of glutathione (GSH) and the enzymatic antioxidants [Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)] were significantly depleted in γ-irradiated mice. Curcumin treatments of mice groups including the 5 days pre-irradiation treated group (protected), the 5 days post-irradiation treated group (treated), and the curcumin treated group 5 days pre- and post-irradiation (protracted), have attenuated the liver toxic effects of γ-rays as manifested by reducing the levels of TBARS, HP, XO and DNA fragmentation. Curcumin has also rescued the depletion of GSH and the enzymatic-antioxidant status.ConclusionsCurcumin has significant radio-protective and radio-recovery activities in γ-irradiated mice. It has antioxidant potential against γ-rays-induced cytogenetic, molecular and biochemical lesions in mice.

Role of DNA methylation in long-term low-dose γ-rays induced adaptive response in human B lymphoblast cells

Purpose: With widespread use of ionizing radiation, more attention has been attracted to low-dose radiation (LDR); however, the mechanisms of long-term LDR-induced bio-effects are unclear. Here, we applied human B lymphoblast cell line HMy2.CIR to monitor the effects of long-term LDR and the potential involvement of DNA methylation.Materials and methods: HMy2.CIR cells were irradiated with 0.032 Gy γ-rays three times per week for 1–4 weeks. Some of these primed cells were further challenged with 2 Gy γ-rays. Cell proliferation, micronuclei formation, gene expression of DNA methyltransferases (DNMT), levels of global genomic DNA methylation and protein expression of methyl CpG binding protein 2 (MeCP2) and heterochromatin protein-1 (HP1) were measured.Results: Long-term LDR enhanced cell proliferation and clonogenicity and triggered a cellular adaptive response (AR). Furthermore, global genomic DNA methylation was increased in HMy2.CIR cells after long-term LDR, accompanied with an increase of gene expression of DNMT1 and protein expression of MeCP2 and HP1. After treatment with 5-aza-2′-deoxycytidine (5-aza-dC), a DNA methyltransferase inhibitor, the long-term LDR-induced global genomic DNA hypermethylation was decreased and the AR was eliminated.Conclusion: Global genomic DNA hypermethylation accompanied with increases of DNMT1 and MeCP2 expression and heterochromatin formation might be involved in long-term LDR-induced adaptive response.

Effects of Haberlea rhodopensis extract on antioxidation and lipid peroxidation in rabbits after exposure to 60Co-γ-rays

Haberlea rhodopensis extract (HRE) possesses strong antioxidant activity. The aim of the present study was to evaluate the protective ability of HRE against oxidative damage induced by a non-lethal dose of 60 Co-γ-rays. Experimental animals (New Zealand rabbits) were exposed to 2.0 Gy γ-rays before and after HRE administration. Lipid peroxidation (MDA) and activities of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) were analyzed. Results show that administration of HRE before and after irradiation decreased the MDA level and increased SOD and CAT activ- ity, thus providing protection against the radiation-induced decrease in antioxidative ability and increase in lipid peroxida- tion. This finding supports the idea that HRE is a potent free radical scavenger and antioxidant.

Ionizing radiation causes active degradation and reduces matrix synthesis in articular cartilage

Purpose: Little is known regarding radiation effects on adult articular (joint) cartilage, though joint damage has been reported following cancer treatment or occupational exposures. The aim of this study was to determine if radiation can reduce cartilage matrix production, induce cartilage degradation, or interfere with the anabolic effects of IGF-1.Materials and methods: Isolated chondrocytes cultured in monolayers and whole explants harvested from ankles of human donors and knees of pigs were irradiated with 2 or 10 Gy γ-rays, with or without IGF-1 stimulation. Proteoglycan synthesis and IGF-1 signaling were examined at Day 1; cartilage degradation throughout the first 96 hours.Results: Human and pig cartilage responded similarly to radiation. Cell viability was unchanged. Basal and IGF-1 stimulated proteoglycan synthesis was reduced following exposure, particularly following 10 Gy. Both doses decreased IGF-induced Akt activation and IGF-1 receptor phosphorylation. Matrix metalloproteinases (ADAMTS5, MMP-1, and MMP-13) and proteoglycans were released into media after 2 and 10 Gy.Conclusions: Radiation induced an active degradation of cartilage, reduced proteoglycan synthesis, and impaired IGF-1 signaling in human and pig chondrocytes. Lowered Akt activation could account for decreased matrix synthesis. Radiation may cause a functional decline of cartilage health in joints after exposure, contributing to arthropathy.

Analysis of a Metalloporphyrin Antioxidant Mimetic (MnTE-2-PyP) as a Radiomitigator: Prostate Tumor and Immune Status

Due to radiation-induced immune depression and development of pathologies such as cancer, there is increasing urgency to identify radiomitigators that are effective when administered after radiation exposure. The main goal of this study was to determine the radiomitigation capacity of MnTE-2-PyP[Mn(III) tetrakis (N-ethylpyridinium-2-yl) porphyrin], a superoxide dismutase (SOD) mimetic, and evaluate leukocyte parameters in spleen and blood. C57BL/6 mice were total-body exposed to 2 Gy γ-rays (Co-60), i.e., well below a lethal dose, followed by subcutaneous implantation of 5 × 10(5) RM-9 prostate tumor cells and initiation of MnTE-2-PyP treatment (day 0); interval between each procedure was 1-2 h. The drug was administered daily (12 times). Tumor progression was monitored and immunological analyses were performed on a subset per group on day 12. Animals treated with MnTE-2-PyP alone had significantly slower tumor growth compared to mice that did not receive the drug (P < 0.05), while radiation alone had no effect. Treatment of tumor-bearing mice with MnTE-2-PyP alone significantly increased spleen mass relative to body mass; the numbers of splenic white blood cells (WBC) and lymphocytes (B and T), as well as circulating WBC, granulocytes, and platelets, were high compared to one of more of the other groups (P < 0.05). The results show that MnTE-2-PyP slowed RM-9 tumor progression and up-regulated immune parameters, but mitigation of the effects of 2 Gy total-body irradiation were minimal.

Exposure to Heavy Ion Radiation Induces Persistent Oxidative Stress in Mouse Intestine

Ionizing radiation-induced oxidative stress is attributed to generation of reactive oxygen species (ROS) due to radiolysis of water molecules and is short lived. Persistent oxidative stress has also been observed after radiation exposure and is implicated in the late effects of radiation. The goal of this study was to determine if long-term oxidative stress in freshly isolated mouse intestinal epithelial cells (IEC) is dependent on radiation quality at a dose relevant to fractionated radiotherapy. Mice (C57BL/6J; 6 to 8 weeks; female) were irradiated with 2 Gy of γ-rays, a low-linear energy transfer (LET) radiation, and intestinal tissues and IEC were collected 1 year after radiation exposure. Intracellular ROS, mitochondrial function, and antioxidant activity in IEC were studied by flow cytometry and biochemical assays. Oxidative DNA damage, cell death, and mitogenic activity in IEC were assessed by immunohistochemistry. Effects of γ radiation were compared to 56Fe radiation (iso-toxic dose: 1.6 Gy; energy: 1000 MeV/nucleon; LET: 148 keV/µm), we used as representative of high-LET radiation, since it's one of the important sources of high Z and high energy (HZE) radiation in cosmic rays. Radiation quality affected the level of persistent oxidative stress with higher elevation of intracellular ROS and mitochondrial superoxide in high-LET 56Fe radiation compared to unirradiated controls and γ radiation. NADPH oxidase activity, mitochondrial membrane damage, and loss of mitochondrial membrane potential were greater in 56Fe-irradiated mice. Compared to γ radiation oxidative DNA damage was higher, cell death ratio was unchanged, and mitotic activity was increased after 56Fe radiation. Taken together our results indicate that long-term functional dysregulation of mitochondria and increased NADPH oxidase activity are major contributing factors towards heavy ion radiation-induced persistent oxidative stress in IEC with potential for neoplastic transformation.

Space-relevant radiation modifies cytokine profiles, signaling proteins and Foxp3+ T cells

Purpose: The major goal was to evaluate effects of various radiation regimens on leukocyte populations relatively long-term after whole-body irradiation.Materials and methods: C57BL/6 mice were exposed to-low-dose/low-dose rate (LDR) 57Co γ-rays (0.01 Gy, 0.03 cGy/h), with and without acute 2 Gy proton (1 Gy/min) or γ-ray (0.9 Gy/min) irradiation; analyses were done on days 21 and 56 post-exposure.Results: Numerous radiation-induced changes were noted at one or both time points. Among the most striking differences (P < 0.05) were: (i) High percentage of CD4+CD25+Foxp3+ T cells in spleens from the Proton vs. LDR, Gamma and LDR + Proton groups (day 56); (ii) high interleukin-2 (IL-2) in spleen supernatants from the LDR and LDR + Proton groups vs. 0 Gy (day 56), whereas IL-10 was high in the LDR + Gamma group vs. 0 Gy (day 56); (iii) difference in transforming growth factor-β1 (TGF-β1) in spleen supernatants from Proton and LDR + Proton groups vs. Gamma and LDR + Gamma groups (both days); (iv) low TGF-β1 in blood from LDR + Proton vs. LDR + Gamma group (day 21); and (v) high level of activated cJun N-terminal kinase (JNK) in CD4+ T cells from LDR + Proton vs. LDR + Gamma group (day 21).Conclusions: The findings demonstrate that at least some immune responses to acute 2 Gy radiation were dependent on radiation quality time of assessment, and pre-exposure to LDR γ-rays.

γ-Ray-associated XBP-1+ macrophages as an inducer of M2 macrophages (117.3)

Abstract The susceptibility of mice to infections with opportunistic pathogens is strongly influenced by M2MΦ appeared in association with whole body γ-irradiation. Therefore, in this study, we investigated why M2MΦ were predominantly generated in mice exposed to whole body γ-irradiation. F4/80+ MΦ were isolated from peritoneal exudates of mice 6-24 h after 5 Gy of γ-irradiation. The expressions of XBP-1 in these MΦ preparations were detected by Western Blot. The production and intracellular CCL2 expression by XBP-1+ MΦ were assayed by ELISA and flow cytometry. In some experiments, resident MΦ were cultured with media supplemented with culture fluids of XBP-1+ MΦ (33%, v/v). MΦ with the ability to produce IL-10 and not produce IL-12 were considered as M2MΦ. In the results, XBP-1+ MΦ were demonstrated in peritoneal MΦ preparations isolated from mice irradiated with 5 Gy of γ-rays. CCL2 was detected in culture fluids of XBP-1+ MΦ. Also, intracellular CCL2 was detected in XBP-1+ MΦ by flow cytometry. The conversion of MΦ from resident MΦ to M2MΦ was demonstrated when resident MΦ were cultured with media supplemented with the culture fluids of XBP-1+ MΦ. Resident MΦ did not change to M2MΦ when they were cultured with XBP-1+ MΦ culture fluids previously depleted of CCL2. These results indicate that the MΦ conversion from resident MΦ to M2MΦ is stimulated by CCL2 released from XBP-1+ MΦ that appear in association with whole body γ-irradiation.

The therapeutic effects of Zingiber officinale extract on mice irradiated by 60Co γ-ray

Radiation can induce the acute and chronic radiation sickness via physical, chemical and biological mechanisms. In this study, we further investigated the therapeutic effects of gingerol on radiated mice. Mice were given gingerol at 800 mg/kg B.W. by oral gavage once daily for 5 consecutive days after exposure to 1, 3, 5 and 7 Gy of 60Co-gamma-radiation. Gingerol treated mice after irradiated by 3 and 5 Gy significantly increased the spleen index compared to 3 and 5 Gy irradiation+DDW mice, respectively. Besides, the gingerol treatment facilitated the recovery of white blood cells (WBC), lymphocytes (LYM), red blood cell (RBC) and hemoglobin (HGB) cell number at all the exposure doses. Moreover, the irradiated mice showed a dose-dependent depletion in superoxide dismutase (SOD) activities and total anti-oxidative capacity (T-AOC), while elevation in the malondialdehyde (MDA) contents, however, gingerol treated mice after irradiation increased activities of SOD and T-AOC, and decreased the MDA levels in liver to a certain extent in all the exposure dose groups. In addition, the gingerol reduced the numbers of micronuclei (MN) of polychromatic erythrocytes (PCEs) in the bone marrow after mice were irradiated by 0, 1, 3, 5 Gy of γ-ray. Together, the findings indicated that gingerol had the therapeutic effects on mice against hematopoietic suppression and anti-oxidative damage caused by irradiation. Key words: Zingiber officinale extract, 60Co, γ-ray, mice, free radical, superoxide dismutase (SOD), radiation; hematopoietic suppression, antioxidation.

Irradiation Alters MMP-2/TIMP-2 System and Collagen Type IV Degradation in Brain

Blood-brain barrier (BBB) disruption is one of the major consequences of radiation-induced normal tissue injury in the central nervous system. We examined the effects of whole-brain irradiation on matrix metalloproteinases (MMPs)/tissue inhibitors of metalloproteinases (TIMPs) and extracellular matrix (ECM) degradation in the brain. Animals received either whole-brain irradiation (a single dose of 10 Gy γ-rays or a fractionated dose of 40 Gy γ-rays, total) or sham-irradiation and were maintained for 4, 8, and 24 h following irradiation. mRNA expression levels of MMPs and TIMPs in the brain were analyzed by real-time reverse transcriptase-polymerase chain reaction (PCR). The functional activity of MMPs was measured by in situ zymography, and degradation of ECM was visualized by collagen type IV immunofluorescent staining. A significant increase in mRNA expression levels of MMP-2, MMP-9, and TIMP-1 was observed in irradiated brains compared to that in sham-irradiated controls. In situ zymography revealed a strong gelatinolytic activity in the brain 24 h postirradiation, and the enhanced gelatinolytic activity mediated by irradiation was significantly attenuated in the presence of anti-MMP-2 antibody. A significant reduction in collagen type IV immunoreactivity was also detected in the brain at 24 h after irradiation. In contrast, the levels of collagen type IV were not significantly changed at 4 and 8 h after irradiation compared with the sham-irradiated controls. The present study demonstrates for the first time that radiation induces an imbalance between MMP-2 and TIMP-2 levels and suggests that degradation of collagen type IV, a major ECM component of BBB basement membrane, may have a role in the pathogenesis of brain injury.

In vivo versus in vitro individual radiosensitivity analysed in healthy donors and in prostate cancer patients with and without severe side effects after radiotherapy

Background: A high cellular radiosensitivity may be connected with a risk for development of severe side effects after radiotherapy and indicate cancer susceptibility. Hence, a fast and robust in vitro test is desirable to identify radiosensitive individuals.Materials and methods: The study included 25 prostate cancer patients with severe side effects (S) and 25 patients without severe side effects (0) after radiotherapy as well as 23 male healthy age-matched donors. Blood samples were exposed to 0.5 Gy or 1 Gy of γ-rays. The initial level of double-strand breaks (dsb) and repair kinetics measured by phosphorylation of histone H2A (γ-H2AX-assay), apoptosis (Annexin V-assay) and the induction of chromatid aberrations after irradiation in the G2-phase of the cell cycle (G2-assay) were analysed.Results: A significant higher chromatid aberration yield was found in lymphocytes from prostate cancer patients when compared to healthy donors. We found no significant differences between patients S and patients 0.Conclusions: There is no obvious correlation between clinical and cellular radiosensitivity in lymphocytes of prostate cancer patients when all chosen in vitro assays are considered. Although 25% of the patients showed both severe side effects and increased radiation-induced chromosomal sensitivity, predictive value of G2-assay is doubtful.