Body X-irradiation Research Articles

MIIST305 mitigates gastrointestinal acute radiation syndrome injury and ameliorates radiation-induced gut microbiome dysbiosis.

High-dose radiation exposure results in gastrointestinal (GI) acute radiation syndrome identified by the destruction of mucosal layer, intestinal epithelial barrier dysfunction, and aberrant inflammatory responses. In addition, radiation causes gut microbiome dysbiosis characterized by diminished microbial diversity, reduction in the abundance of beneficial commensal bacteria, and the spread of bacterial pathogens that trigger the recruitment of immune cells and the production of pro-inflammatory factors that lead to further GI tissue damage. Currently, there are no FDA- approved countermeasures that can treat radiation-induced GI injury. To meet this critical need, Synedgen Inc ., has developed a glycopolymer radiomitigator (MIIST305) that is specifically targeted to the GI tract which acts by intercalating into the mucus layer and the glycocalyx of intestinal epithelial cells that could potentially ameliorate the deleterious effects of radiation. Male C57BL/6J adult mice were exposed to 13 Gy total body X-irradiation with 5% bone marrow shielding and MIIST305 was administered on days 1, 3, and 5 post-irradiation. Approximately 85% of the animals survived the irradiation exposure and were apparently healthy until the end of the 30-day study period. In contrast, no control, vehicle-treated animals survived past day 10 at this radiation dose. We show that MIIST305 improved intestinal epithelial barrier function and suppressed systemic inflammatory response mediated by radiation-induced pro-inflammatory cytokines. Taxonomic profiling and community structure of the fecal and colonic mucosa microbiota demonstrated that MIIST305 treatment increased microbial diversity and restored abundance of beneficial commensal bacteria, including Lactobacillus and Bifidobacterium genera, while suppressing potentially pathogenic bacteria compared with vehicle-treated animals. In summary, MIIST305 is a novel GI-targeted therapeutic that greatly enhances survival in mice exposed to lethal radiation and protects the GI tract from injury by restoring a balanced gut microbiota and effectively reducing proinflammatory responses. Further development of this drug as an FDA-approved medical countermeasure will be of critical importance in the event of a radiation public health emergency.

Protective effects of L-carnitine on X irradiation-induced uterus injury via antioxidant and anti-inflammatory pathways

Purpose Ionizing radiation causes oxidative stress induced tissue damage as well as a decline in reproduction incidence. The purpose of our study was to evaluate the effects of L-carnitine on radiation-induced uterine injury. Materials and methods Thirty Wistar albino rats were classified into five groups. Physiological saline was administered intraperitoneally to the control group. A single dose of 8.3 Gy whole body X-irradiation was applied to the radiation-1 and radiation-2 groups. These groups were sacrificed on the 6th hour and 4th day, respectively, after irradiation. Radiation-1 + L-carnitine and radiation-2 + L-carnitine groups received a daily dose of 200 mg/kg L-carnitine in addition to the same dose of irradiation. L-carnitine was also applied one day before and four days after irradiation. Results L-carnitine therapy partially blocks the depletion of the deep glands and radiation-induced flattening of the glandular epithelium and endometrial surface. Proinflammatory cytokines such as IL-1β, IL-6 and TNF-α were found to be significantly expressed in the uterus tissue of irradiated mice. In the radiation groups, NFκB and PARP-1 expressions in uterine tissue was significantly increased compared to L-carnitine treated and the control groups. It was observed that the oxidative stress index increased in the radiation groups, but decreased in the L-carnitine applied groups. Conclusions Our findings showed that L-carnitine has a positive effect on radiation-induced uterine damage. L-carnitine may be a potential safe radio protective agent during radiotherapy for pelvic cancer provided the tumor is not protected from radiation damage to the same extent as the normal tissue is. However, prospective clinical trial studies are necessary to understand its efficacy.

Serum Proteomic and Oxidative Modification Profiling in Mice Exposed to Total Body X-Irradiation.

The details of the dose-dependent response of serum proteins exposed to ionizing radiation, especially the oxidative modification response in amino acid sequences of albumin, the most abundant protein, are unknown. Thus, a proteomic analysis of the serum components from mice exposed to total body X-irradiation (TBI) ranging from 0.5 Gy to 3.0 Gy was conducted using LC-MS/MS. The analysis of oxidative modification sequences of albumin (mOMSA) in TBI mouse serum revealed significant moderate or strong correlations between the X-irradiation exposure dose and modification of 11 mOMSAs (especially the 97th, 267th and 499th lysine residues, 159th methionine residue and 287th tyrosine residues). In the case of X-irradiation of serum alone, significant correlations were also found in the 14 mOMSAs. In addition, a dose-dependent variation in six proteins (Angiotensinogen, Odorant-binding protein 1a, Serine protease inhibitor A3K, Serum paraoxonase/arylesterase 1, Prothrombin and Epidermal growth factor receptor) was detected in the serum of mice exposed to TBI. These findings suggest the possibility that the protein variation and serum albumin oxidative modification responses found in exposed individuals are important indicators for considering the effects of radiation on living organisms, along with DNA damage, and suggests their possible application as biomarkers of radiation dose estimation.

Biochemical effects of low-dose whole body x-irradiation on mouse liver and the protective action of ectoine

Purpose: To investigate the possible role of ectoine, which is known to protect protein hydration and folding and structural organization of biological membranes, in protecting mouse liver against low-dose x-irradiation. Methods: The study included thirty Swiss albino mice weighing 20 - 22 g each, which were divided into five groups of six animals each: group (1) naive animals serving as control, group (2) animals irradiated with a whole-body 2 Gy single dose of x-ray, and sacrificed after one day, group (3) x-irradiated and sacrificed after one week (each animal in the 3 groups received 0.2 mL saline daily by oral gavage). Group 4 consisted of x-irradiated animals dosed with ectoine 200 mg/kg in saline and sacrificed after one day. Group 5 cmoprised of x-irradiated animals and were dosed daily with ectoine 200 mg/kg and sacrificed after one week. The evaluated inflammation parameters in the animals’ liver were interleukin- 1β (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10) and prostaglandin E2 (PGE2). Furthermore, the oxidative stress parameters, viz, malondialdehyde (MDA), reduced glutathione (GSH), oxidized glutathione (GSSG) and their ratio (GSH/GSSG) were also assessed. Results: Whole body low-dose x-irradiation resulted in statistically significant (p ≤ 0.05) increases in all ILs tested as well as PGE2 of mice liver. Indications of oxidative stress included elevated levels of MDA and oxidized glutathione with decreased reduced glutathione. The effects of radiation were progressive and the changes in the tested parameters increased from day 1 to day 7. Administration of ectoine significantly (p ≤ 0.05) ameliorated the biochemical effects induced by whole body x-irradiation. Furthermore, the modulating action was dependent on the accumulation of ectoine, as it was more effective after repeated administration. Conclusion: Ectoine has a post-irradiation protective effect on mouse liver via its action on inflammatory and oxidative stress pathways. It probably has similar action in other vital organs. Preventive treatment of healthcare personnel and technicians frequently exposed to low doses of radiation with ectoine is worth investigating. Keywords: X-irradiation, Ectoine, Oxidative stress, Mice, Radioprotection

Dotting the eyes: mouse strain dependency of the lens epithelium to low dose radiation-induced DNA damage

Purpose: Epidemiological evidence regarding the radiosensitivity of the lens of the eye and radiation cataract development has led to changes in the EU Basic Safety Standards for protection of the lens against ionizing radiation. However, mechanistic details of lens radiation response pathways and their significance for cataractogenesis remain unclear. Radiation-induced DNA damage and the potential impairment of repair pathways within the lens epithelium, a cell monolayer that covers the anterior hemisphere of the lens, are likely to be involved.Materials and Methods: In this work, the lens epithelium has been analyzed for its DNA double-strand break (DSB) repair response to ionizing radiation. The responses of epithelial cells located at the anterior pole (central region) have been compared to at the very periphery of the monolayer (germinative and transitional zones). Described here are the different responses in the two regions and across four strains (C57BL/6, 129S2, BALB/c and CBA/Ca) over a low dose (0–25 mGy) in-vivo whole body X-irradiation range up to 24 hours post exposure.Results: DNA damage and repair as visualized through 53BP1 staining was present across the lens epithelium, although repair kinetics appeared non-uniform. Epithelial cells in the central region have significantly more 53BP1 foci. The sensitivities of different mouse strains have also been compared.Conclusions: 129S2 and BALB/c showed higher levels of DNA damage, with BALB/c showing significantly less inter-individual variability and appearing to be a more robust model for future DNA damage and repair studies. As a result of this study, BALB/c was identified as a suitable radiosensitive lens strain to detect and quantify early low dose ionizing radiation DNA damage effects in the mouse eye lens specifically, as an indicator of cataract formation.

Post-irradiation protective effects of ectoine on brain and testicles in male mice.

The present study aimed to investigate the possible post-irradiation protective effects of ectoine on CNS and testes of male mice. The study included thirty male Swiss albino mice (20-22 gm). Mice were divided into five groups (six each); controls (injected intraperitoneally with 0.2ml saline), irradiated group 1 (received six Gy whole body x-irradiation single dose, injected with saline, and sacrificed after one day), irradiated group 2 (x-irradiated, injected with saline, and sacrificed after one week), ectoine group 1 (x-irradiated, injected with 200mg/kg ectoine, and sacrificed after one day), and ectoine group 2 (x-irradiated, injected daily with 200mg/kg ectoine, and sacrificed after one week). IL-1β, IL-6, IL-10, PGE2, MDA, GSH, GSSG, and GSH/GSSG ratio were evaluated in CNS and testes. IL-1β, IL-6, IL-10, PGE2, and MDA are significantly elevated in the CNS and testes of x-irradiated groups when compared with controls. IL-1β, IL-6, IL-10, and PGE2 significantly elevated at one week than one day while MDA significantly decreased. A significant decrease in the concentration of GSH and in the GSH/GSSG ratios coupled with an opposite effect on GSSG was noted. Ectoine treatment significantly ameliorated the biochemical effects induced by whole body x-irradiation. All the tested parameters tended to go back to near control values. It was noted that the modulating action was dependent on the accumulation of ectoine as it was more effective after repeated administration. Ectoine has post-irradiation protective effects on CNS and testes via its action on inflammatory and oxidative stress pathways.

Inhibition effect of disulfiram combined with Cu on the growth of human Burkitt lymphoma cell xenografts in nude mice

Objective To investigate the effects of disulfiram(DS) combined with Cu on the human Burkitt lymphoma cell xenografts in nude mice. Methods Burkitt lymphoma xenograft was established by subcutaneous injection of Raji cell into nude mice after 2 Gy whole body X-irradiation(1×107 Raji cells were resuspended in 200 μl saline). 18 bearing tumor mice were randomly divided into control group, DS group and DS/Cu group. During the experiment, the effects of DS/Cu on the nude mice with tumors were examined, including the tumor volumes, weights and the growth curves of xenograft tumor. Histopathological examination of tumor tissue was observed with optical microscape. The protein expression levels of p-JNK and c-jun were also detected by Western blot. Results Subsequent tumor size and weight in DS or DS/Cu-treated animals were (67.71±2.15) mm3, (33.35±7.74) mm3 and (43.35±4.22) mg, (18.05±2.88) mg. One-way ANOVA analysis indicated that the tumor size and weight in DS or DS/Cu-treated animals were reduced significantly relative to tumors in vehicle-treated animals(F=27.579, P=0.000; F=16.369, P=0.000). Furthermore, multiple comparisons revealed that the DS or DS/Cu-treated animals had significantly reduced tumor size and weight compared with control animals (all P<0.05). There were significant differences in tumor size and weight between DS or DS/Cu-treated animals (both P<0.05). Tumor inhibition rates in DS or DS/Cu group were 63.48 % and 80.24 %, respectively. An increase of apoptosis changes in the xenograft tumor cells in DS or DS/Cu treated mice were more significant. Western blot showed that the p-JNK and c-jun protein expressions in the tumors were improved after the DS or DS/Cu treatment, more obvious in DS/Cu treatment. Conclusion DS/Cu can inhibit the growth of xenografts, and one possible mechanism may involve the regulation of JNK signal pathway. Key words: Disulfiram; Copper; Burkitt lymphoma; JNK signal pathway

Influence of Whole Body X-irradiation on the Liver and Possible Protective Effect by the Compatible Solute Ectoine in a Mouse Model

Exposure of mammals to ionizing radiation leads to the development of a complex dose-dependent series of physiological and pathological changes. The present study was undertaken to investigate the effect of whole body x-irradiation of male mice with a single w dose of 6 Gy on the levels of some cytokines and parameters of oxidative stress, after one and seven days, in the liver. The possible protective effect of the compatible solute ectoine, which is known to reduce cell stress effects on the molecular level, was evaluated. The x-irradiated mice showed elevated interleukins in the liver. The levels of both the pro-inflammatory (IL-1β and IL-6) and the anti-inflammatory (IL-10) interleukins reached several times the control value with quantitative differences. The disturbance by low-dose x-irradiation also affected PGE2. Malondialdehyde, used as indication of oxidative stress, was elevated in the livers of x-irradiated mice. Although, there were no statistically significant differences in the results of total glutathione among the irradiated mice as compared to control values, there were differences among the values of the reduced and oxidized forms. The calculated redox potentials, showed some variations in the different groups, but were all within the values indicating that the cells are in the proliferative phase and far from the apoptotic phase. Treatment with ectoine modulated all the tested biochemical effects induced by x-irradiation in the liver. All the tested parameters had a tendency to go back to near control values.

Lymphoid and Myeloid Recovery in Rhesus Macaques Following Total Body X-Irradiation.

Recovery from severe immunosuppression requires hematopoietic stem cell reconstitution and effective thymopoiesis to restore a functional immune cell repertoire. Herein, a model of immune cell reconstitution consequent to potentially lethal doses of irradiation is described, which may be valuable in evaluating potential medical countermeasures. Male rhesus macaques were total body irradiated by exposure to 6.00 Gy 250 kVp x-radiation (midline tissue dose, 0.13 Gy min), resulting in an approximate LD10/60 (n = 5/59). Animals received medical management, and hematopoietic and immune cell recovery was assessed (n ≤ 14) through 370 d post exposure. A subset of animals (n ≤ 8) was examined through 700 d. Myeloid recovery was assessed by neutrophil and platelet-related parameters. Lymphoid recovery was assessed by the absolute lymphocyte count and FACS-based phenotyping of B- and T-cell subsets. Recent thymic emigrants were identified by T cell receptor excision circle quantification. Severe neutropenia, lymphopenia, and thrombocytopenia resolved within 30 d. Total CD3+ cells μL required 60 d to reach values 60% of normal, followed by subsequent slow recovery to approximately normal by 180 d post irradiation. Recovery of CD3+4+ and CD3+8+ cell memory and naïve subsets were markedly different. Memory populations were ≥ 100% of normal by day 60, whereas naïve populations were only 57% normal at 180 d and never fully recovered to baseline post irradiation. Total (CD20+) B cells μL were within normal levels by 77 d post exposure. This animal model elucidates the variable T- and B-cell subset recovery kinetics after a potentially lethal dose of total-body irradiation that are dependent on marrow-derived stem and progenitor cell recovery, peripheral homeostatic expansion, and thymopoiesis.

Enhanced heat shock protein 25 immunoreactivity in cranial nerve motoneurons and their related fiber tracts in rats prenatally-exposed to X-irradiation.

Alterations in histoarchitecture of the brainstem were examined immunohistochemically in 4-week-old rats with a single whole body X-irradiation at a dose of 0.5, 1.0, or 1.5 Gy on embryonic day (ED) 15 using anti-heat shock protein 25 (HSP25). HSP25 immunostaining was seen in the neuronal perikarya of cranial nerve motoneurons, that is, the motor and mesencephalic nuclei of the trigeminal nerve, facial nucleus, abducens nucleus and accessory facial nucleus in the pons, and the ambiguous nucleus, dorsal nucleus of vagus nerve and hypoglossus nucleus in the medulla oblongata of intact controls. In 0.5 to 1.5 Gy-irradiated rats, HSP25 immunostaining in those neurons was more intense than in controls, while the most intense immunostaining was marked in 1.5 Gy-irradiated rats. HSP25 immunostaining was also apparent in the spinal tract of the trigeminal nerve and facial nerve tracts in 0.5 to 1.5 Gy-irradiated rats, but was faint in controls. Interestingly, HSP25 immunostaining was aberrantly enhanced in dendritic arbors in the magnocellular region of medial vestibular nucleus of 0.5-1.5 Gy-irradiated rats. Those arbors were identified as excitatory secondary vestibulo-ocular neurons by double immunofluorescence for HSP25 and SMI-32. The results suggest an increase of HSP25 expression in cranial nerve motoneurons and their related fiber tracts from prenatal exposure to ionizing irradiation. This may be an adaptive response to chronic hypoxia due to malformed brain arteries caused by prenatal ionizing irradiation.

Purple grape juice as a protector against acute x-irradiation induced alterations on mobility, anxiety, and feeding behaviour in mice.

The aim of this work was to test the hypothesis that a moderate intake of organic purple grape juice shows a positive radiomodifier effect over early behavioural damage following acute X-irradiation in mice. Anxiety-, locomotion-, and feeding-related responses to 6 Gy total body X-irradiation (TBI) were studied via open field, Rotarod, and feeding/drinking recording. Thirty-two male mice weighing 25-30 g were grouped according grape juice (J) or water (W) ad libitum drinking and either non-irradiated (N) or irradiated (R). 24 h post-TBI the access frequency to the center and corners of the open field was decreased, and the total stay in the corners increased, in RW vs. NW mice. Anxiety-related parameters decreased in RJ vs. RW mice. Rotarod latency times increased 72 h post-TBI in RJ vs RW mice. No overall changes in food and drink intake were observed along the experimental period. On the irradiation day, bout number was increased and bout duration was decreased in RW mice. The changes were reversed by purple grape juice intake. Grape juice intake before and after TBI can overcome several radiation-induced changes in behaviour within 24-72 hours after sub-lethal X-irradiation. This beneficial effect on short-term anxiety and mobilityrelated activities could probably be included in the list of flavonoid bio-effects. The present findings could be relevant in designing preventive interventions aimed to enhance body defense mechanisms against short-term irradiation damage.

Optimal conditions of LDR to protect the kidney from diabetes: Exposure to 12.5 mGy X-rays for 8 weeks efficiently protects the kidney from diabetes

AimsWe reported the attenuation of diabetes-induced renal dysfunction by exposure to multiple low-dose radiation (LDR) at 25mGy every other day by suppressing renal oxidative damage. We here explored the optimal conditions of LDR to protect the kidney from diabetes. Main methodsMale C57BL/6J mice with type 1 diabetes were induced with multiple injections of low-dose streptozotocin. Diabetic mice received whole body X-irradiation at a dose of 12.5, 25 or 50mGy every other day for either 4 or 8weeks. Age-matched normal mice were similarly irradiated at the dose of 25mGy for 4 or 8weeks. The renal function and histopathological changes were examined at the 4th and 8th weeks of the study. Key findingsDiabetes induced renal dysfunction is shown by the decreased creatinine and increased microalbumin in the urine. Renal oxidative damage, detected by protein nitration and lipid oxidation, and remodeling, reflected by increased expression of connective tissue growth factor, collagen IV and fibronectin, were significantly increased in diabetic mice. All these renal pathological and function changes in diabetic mice were significantly attenuated by exposure to LDR at all regimens, among which, however, exposure to LDR at 12.5mGy for 8weeks provided the best protective effect on the kidney of diabetic mice. SignificanceOur results suggest that whole-body LDR at 12.5mGy every other day for 8weeks is the optimal condition of LDR to protect the kidney from diabetes.

Dose‐related cerebellar abnormality in rats with prenatal exposure to X‐irradiation by magnetic resonance imaging volumetric analysis

Cerebellar abnormalities in 4-week-old rats with a single whole body X-irradiation at a dose of 0.5, 1.0, or 1.5 Gy on embryonic day (ED) 15 were examined by magnetic resonance imaging (MRI) volumetry. A 3D T2 W-MRI anatomical sequence with high-spatial resolution at 11.7-tesla was acquired from the fixed rat heads. By MRI volumetry, whole cerebellar volumes decreased dose-dependently. Multiple linear regression analysis revealed that the cortical volume (standardized β=0.901; P<0.001) was a major explanatory variable for the whole cerebellar volume, whereas both volumes of the white matter and deep cerebellar nuclei also decreased depending on the X-irradiation dose. The present MRI volumetric analysis revealed a dose-related cerebellar cortical hypoplasia by prenatal exposure to X-irradiation on E15.

Gamma-tocopherol-N,N-dimethylglycine ester as a potent post-irradiation mitigator against whole body X-irradiation-induced bone marrow death in mice

We examined the radioprotective and mitigative effects of gamma-tocopherol-N,N-dimethylglycine ester (GTDMG), a novel water-soluble gamma-tocopherol derivative, against X-irradiation-induced bone marrow death in mice. Mice (C3H, 10 weeks, male) were injected intraperitoneally with GTDMG suspended in a 0.5% methyl cellulose solution before or after receiving of 7.5-Gy whole body X-irradiation. GTDMG significantly enhanced the 30-day survival rate when given 30 min before or immediately after the irradiation. Its mitigative activity (administered after exposure) was examined further in detail. The optimal concentration of GTDMG given immediately after irradiation was around 100 mg/kg body weight (bw) and the 30-day survival rate was 97.6 ± 2.4%. When GTDMG was administered 1, 10 and 24 h post-irradiation, the survival rate was 85.7 ± 7.6, 75.0 ± 9.7 and 36.7 ± 8.8%, respectively, showing significant mitigation even at 24 h after irradiation (P < 0.05). The value of the dose reduction factor (100 mg/kg bw, given intraperitoneally (i.p.) immediately after irradiation) was 1.25. GTDMG enhanced the recovery of red blood cell-, white blood cell-, and platelet-counts after irradiation and significantly increased the number of endogenous spleen colonies (P < 0.05). Subcutaneous (s.c.) administration also had mitigative effects. In conclusion, GTDMG is a potent radiation mitigator.

Prolonged anti-emetic activity and 5-HT3-receptor antagonism by BRL 46470 in conscious ferrets.

The anti-emetic activity of oral and intravenously-administered BRL 46470 (endo-N-(8-methyl-8-azabicyclo[3.2.1]oct-3yl)-2,3-dihydro-3,3- dimethyl-indole-1-carboxamide HCl) has been assessed in conscious ferrets. BRL 46470 (0.05-0.5 mg kg-1, p.o.) dose-dependently prevented emesis evoked over a 2 h period by total body X-irradiation. This anti-emetic activity occurred with oral or intravenously-administered BRL 46470 even when dosed 3-4 h before radiation. In conjunction with data obtained in other species, we conclude that BRL 46470 has a potent and long-lasting ability to antagonize actions that are mediated by the 5-HT3 receptor in-vivo.

Abstract 5546: Improved gastrointestinal repair post irradiation with AEOL 10150

Abstract Background Gastrointestinal toxicity, often manifested as ulceration and diarrhoea (mucositis) occurs following exposure to radiation and many chemotherapeutics. Potential treatments include prophylactic damage limitation or therapeutic/mitigatory wound repair dosing regimes. Treatments that are effective mitigators also have biodefence applications. In both the clinic or following nuclear terrorism effective agents may be given in combination with haematological therapies, in addition to standard supportive care agents. Methods AEOL 10150 [5,10,15,20-tetrakis(1,3-diethylimidazolium-2-yl) porphyrinato] manganese (III) pentachloride was administered to C57BL/6 male mice s.c. daily from 24hrs following a single dose of 13Gy total body X-irradiation. AEOL 10150 was administered at a 2x initial loading dose of 40 or 20mg/kg and then subsequently each day at 20 or 10mg/kg respectively. Animals were euthanized 4 and 6 days post irradiation and the number of regenerating small intestinal crypts measured. In a parallel study the levels diarrhoea and animal viability were measured animals exposed to 15Gy partial body X-irradiation (partially lead shielded to protect the bone marrow). Results Treatment with AEOL 10150 increased the number of surviving regenerating crypt observed in histological cross sections of the small intestine 4 days post irradiation. This was highly significant at both doses (p&amp;lt;0.001 for the 40/20mg/kg schedule and p=0.009 for the 20/10 mg/kg schedule). By day 6, where crypt numbers had increased from day 4, numbers were increased but not statistically significant. Levels of crypt fission, necessary to restore crypt numbers, were also increased. At the highest treatment dose animal mortality was only marginally reduced (p=0.115) but the severity and duration of observed diarrhoea was significantly reduced (p=0.021 and p=0.010 respectively). Conclusion AEOL 10150 demonstrated efficacy in both histological and physiological readouts of radiation induced gastrointestinal toxicity. Studies are currently ongoing to investigate whether other dosing schedules can further improve gastrointestinal repair. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5546.

Suppression of autoimmune thyroid disease by FK 506: influence on thyroid-infiltrating cells, adhesion molecule expression and anti-thyroglobulin antibody production.

Autoimmune thyroid disease was induced in female PVG/c rats by neonatal thymectomy, followed by sublethal, whole body x-irradiation. Disease development, assessed by histological evidence of lymphocytic thyroiditis and circulating levels of anti-thyroglobulin antibodies, was reduced significantly by a 3-week course of FK 506 (0.5 or 1.5 mg/kg per day) commencing after the detection of autoantibody production. Thyroid-infiltrating mononuclear cells (MNC) in untreated rats stained predominantly for CD4+ and MHC class II antigen which was expressed widely on dendritic cells. Fewer infiltrating cells expressed TCR alpha/beta, CD5, CD8 or LFA-1 beta. Intercellular adhesion molecule-1 (ICAM-1) was observed on MNC, vascular endothelial cells and a minority of residual thyroid epithelial cells. FK 506 administration reduced markedly the incidence of infiltrating TCR alpha/beta +, CD5+, CD4+, CD8+, and LFA-1 beta + cells and the expression both of MHC class II antigens and ICAM-1 on MNC, endothelial cells and thyrocytes. Compared with normal PVG/c rats, there were reduced incidences of CD4+ CD8- and CD4- CD8+ lymphocytes and an elevation in the CD4+/CD8+ cell ratio in the spleens of animals with autoimmune thyroiditis. These changes were partially reversed by FK 506. Systemic drug levels estimated by enzyme immunosorbent assay were in excess of those known to blockade cytokine production by CD4+ T lymphocytes in vitro and some evidence of minor renal dysfunction was observed. The results are consistent with a therapeutic effect of FK 506 mediated via interference with CD4+ T lymphocyte function and adhesion molecule-dependent cytotoxic effector mechanisms.

Heat-Treated Mineral-Yeast as a Potent Post-irradiation Radioprotector

In vivo radioprotection of C3H mice by i.p. administration of Zn-, Mn-, Cu-, or Se-containing heat-treated Saccharomyces serevisiae yeast sample was examined. The 30-day survival of the group treated 30 min before 7.5 Gy whole-body X-irradiation with mineral-containing yeast powders suspended in 0.5% methylcellulose was significantly higher than that of control group. When mineral-yeast was administered immediately after irradiation, the survival rate was even higher and Zn- or Cu-yeast showed the highest rate (more than 90%). Although treatment with simple yeast showed a high survival rate (73%), it was significantly lower than that obtained by the Zn-yeast treatment. The effects of Zn-yeast were studied further. When the interval between irradiation and administration was varied, the protective activity of Zn-yeast decreased gradually by increasing the interval but was still significantly high for the administration at 10 h post-irradiation. The dose reduction factor of Zn-yeast (100 mg/kg, i.p. administration immediately after irradiation) was about 1.2. When the suspension of Zn-yeast was fractionated by centrifugation, the insoluble fraction showed a potent effect, while the soluble fraction had only a moderate effect. In conclusion, mineral-yeast, especially Zn-yeast, provides remarkable post-irradiation protection against lethal whole body X-irradiation. The activity is mainly attributable to the insoluble fraction, whereas some soluble components might contribute to the additional protective activity.

Role of metallothionein as a protective factor against radiation carcinogenesis

In order to elucidate the involvement of metallothionein (MT) in radiation carcinogenesis, we examined the susceptibility of MT-I/II null mice to carcinogenesis and oxidative DNA damage resulting from X-irradiation. Eight-week-old female MT-I/II null mice and wild-type mice were exposed to whole-body X-irradiation at doses of 1.0, 1.5 or 2.0 Gy once a week for 6 weeks. Incidence of thymic lymphoma was determined at 24 weeks after the first exposure to X-irradiation. The frequency of thymic lymphomas induced by X-irradiation (at 1.5 and 2.0 Gy) was significantly higher in MT-I/II null mice than in wild-type mice. In addition, although the levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) were increased in the serum and urine of both strains of mice 24 hr after exposure to a single bout of whole body X-irradiation, these increases were significantly greater in the MT-I/II null mice than in the wild-type mice. Thus, the present results suggest that MT plays a protective role against carcinogenesis and oxidative DNA damage caused by X-irradiation.

Differential effects of low- and high-dose X-rays on N-ethyl-N-nitrosourea-induced mutagenesis in thymocytes of B6C3F1 gpt-delta mice

Carcinogenesis in humans is thought to result from exposure to numerous environmental factors. Little is known, however, about how these different factors work in combination to cause cancer. Because thymic lymphoma is a good model of research for combined exposure, we examined the occurrence of mutations in thymic DNA following exposure of B6C3F1 gpt-delta mice to both ionizing radiation and N-ethyl-N-nitrosourea (ENU). Mice were exposed weekly to whole body X-irradiation (0.2 or 1.0Gy), ENU (200ppm) in the drinking water, or X-irradiation followed by ENU treatment. Thereafter, genomic DNA was prepared from the thymus and the number and types of mutations in the reporter transgene gpt was determined. ENU exposure alone increased mutant frequency by 10-fold compared to untreated controls and over 80% of mutants had expanded clonally. X-irradiation alone, at either low or high dose, unexpectedly, reduced mutant frequency. Combined exposure to 0.2Gy X-rays with ENU dramatically decreased mutant frequency, specifically G:C to A:T and A:T to T:A mutations, compared to ENU treatment alone. In contrast, 1.0Gy X-rays enhanced mutant frequency by about 30-fold and appeared to accelerate clonal expansion of mutated cells. In conclusion, repeated irradiation with 0.2Gy X-rays not only reduced background mutation levels, but also suppressed ENU-induced mutations and clonal expansion. In contrast, 1.0Gy irradiation in combination with ENU accelerated clonal expansion of mutated cells. These results indicate that the mode of the combined mutagenic effect is dose dependent.