Oxygen is a very important factor in determining radiosensitivity because it enhances the damage to cellular components caused by ionizing radiation, although mechanisms involved in UV irradiation damage may overlap ionizing radiation effects. This paper emphasizes chemical protection against damage by ionizing radiation and predominantly against the effects of photons (and gamma radiation). It is possible that free radicals and their products induced by ionizing radiation can interact with reactive oxygen species formed during normal processes, such as superoxide and hydrogen peroxide produced by phagocytic cells or during enzymatic processes (xanthine oxidase activity; enzymes involved in eicosanoid metabolism). Metals such as iron can promote free radical damage, whereas some bound metals have radioprotectant potential, e.g., metallothionein and ceruloplasmin. There is increasing evidence that maintenance of the proper oxidation-reduction state of cells by the interconversion of the peptide sulfhydryl glutathione (GSH), and its disulfide form (GSSG) is a factor in the modulation of cellular radiosensitivity. Other protein and nonprotein sulfhydryls may also play a role both as targets of radiation damage and as protectors. Other physiological antioxidants (vitamin E) and antioxidant enzymes are interrelated in their function of controlling oxidative processes. This review concentrates on the role of oxygen, glutathione, andmore » antioxidant enzymes in radiosensitivity and how exogenous chemicals interact with these endogenous factors.« less

The search for treatments to counter potentially lethal radiation-induced injury over the past several decades has led to the development of multiple classes of radiation countermeasures. However, to date only granulocyte colony-stimulating factor (G-CSF; filgrastim, Neupogen)and pegylated G-CSF (pegfilgrastim, Neulasta) have been approved by the United States Food and Drug Administration (FDA) for the treatment of hematopoietic acute radiation syndrome (ARS). Gamma-tocotrienol (GT3) has demonstrated strong radioprotective efficacy in the mouse model, indicating the need for further evaluation in a large animal model. In this study, we evaluated GT3 pharmacokinetics (PK) and efficacy at different doses of cobalt-60 gamma radiation (0.6 Gy/min) using the nonhuman primate (NHP) model. The PK results demonstrated increased area under the curve with increasing drug dose and half-life of GT3. GT3 treatment resulted in reduced group mean neutropenia by 3-5 days and thrombocytopenia by 1-5 days. At 5.8 and 6.5 Gy total-body irradiation, GT3 treatment completely prevented thrombocytopenia. The capability of GT3 to reduce severity and duration of neutropenia and thrombocytopenia was dose dependent; 75 mg/kg treatment was more effective than 37.5 mg/kg treatment after a 5.8 Gy dose. However, the higher GT3 dose (75 mg/kg) was associated with higher frequency of adverse skin effects (small abscess) at the injection site. GT3 treatment of irradiated NHPs caused no significant difference in animal survival at 60 days postirradiation, however, low mortality was observed in irradiated, vehicle-treated groups as well. The data from this pilot study further elucidate the role and pharmacokinetics of GT3 in hematopoietic recovery after irradiation in a NHP model, and demonstrate the potential of GT3 as a promising radioprotector.

Gamma tocotrienol (GT3) has been reported as a potent ameliorator of radiation-induced gastrointestinal (GI) toxicity when administered prophylactically. This study aimed to evaluate the role of GT3 mediated pro- and anti-apoptotic gene regulation in protecting mice from radiation-induced GI damage.Male 10- to 12-weeks-old CD2F1 mice were administered with a single dose of 200mg/kg of GT3 or equal volume of vehicle (5% Tween-80) 24h before exposure to 11Gy of whole-body γ-radiation. Mouse jejunum was surgically removed 4 and 24h after radiation exposure, and was used for PCR array, histology, immunohistochemistry, and immunoblot analysis.Results were compared among vehicle pre-treated no radiation, vehicle pre-treated irradiated, and GT3 pre-treated irradiated groups. GT3 pretreated irradiated groups, both 4h and 24h after radiation, showed greater upregulation of anti-apoptotic gene expression than vehicle pretreated irradiated groups. TUNEL staining and intestinal crypt analysis showed protection of jejunum after GT3 pre-treatment and immunoblot results were supportive of PCR data.Our study demonstrated that GT3-mediated protection of intestinal cells from a GI-toxic dose of radiation occurred via upregulation of antiapoptotic and downregulation of pro-apoptotic factors, both at the transcript as well as at the protein levels.

Purpose . This study was designed to determine the efficacy and mechanisms of radioprotection by the combination of gamma-tocotrienol (GT3) and pentoxifylline (PTX) against acute radiation injury. Materials and Methods . Post-irradiation survival was monitored to determine the most efficacious dose and time of administration of PTX. Dose reduction factor (DRF) was calculated to compare the radioprotective efficacy of the combination. To determine the mechanism of synergistic radioprotection by the combination, mevalonate or calmodulin were coadministered with the GT3-PTX combination. Mevalonate was used to reverse the inhibitory effect of GT3 on 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR), and calmodulin was used to reverse the inhibition of phosphodiesterase (PDE) by PTX. Results . The combination was most effective when 200 mg/kg of PTX was administered 15 min before irradiation along with 200 mg/kg of GT3 (−24 h) and resulted in a DRF of 1.5. White blood cells and neutrophil counts showed accelerated recovery in GT3-PTX-treated groups compared to GT3. Mevalonate had no effect on the radioprotection of GT3-PTX; calmodulin abrogated the synergistic radioprotection by GT3-PTX. Conclusion . The mechanism of radioprotection by GT3-PTX may involve PDE inhibition.

A composite obtained from pure aluminum and multiwall carbon nanotubes by mechanical milling in a high-power mill and ultrasonic mixing is studied. The apparent activation energy and the order of the reaction between carbon nanotubes and aluminum are determined using the Kissinger and Crane equations and differential scanning calorimetry under non-isothermal conditions.

Exposure to ionizing radiation (IR) elicits a set of complex biological responses involving gene expression and protein turnover that ultimately manifest as dysregulation of metabolic processes representing the cellular phenotype. Although radiation biomarkers have been reported in urine and serum, they are not informative about IR mediated tissue or organ specific injury. In the present study we report IR induced metabolic changes in gastrointestinal (GI) tissue of CD2F1 mice using ultra-performance liquid chromatography (UPLC) coupled with electrospray time-of-flight mass spectrometry. Post-radiation GI injury is a critical determinant of survival after exposure to IR. Our results show a distinct dose and time dependent response to GI tissue injury.

Gamma-tocotrienol (GT3), a vitamin E isoform, is shown to induce high levels of granulocyte colony stimulating factor (G-CSF) in mice. G-CSF is a key cytokine used for stimulation of hematopoiesis, and mobilization of hematopoietic stem and progenitor cells into peripheral blood. GT3 is also shown to induce vascular endothelial growth factor (VEGF), another important cytokine necessary for vasculogenesis and endothelial progenitor mobilization. Since GT3 induces both these cytokines, we tested whether GT3 mobilizes hematopoietic and endothelial progenitors in mice. GT3 (200mg/kg) was injected in 10-week-old CD2F1 mice and mobilization of progenitors in peripheral blood was analyzed at 24, 48, and 72h post-administration. Circulating hematopoietic progenitor cells (HPCs, Lin−, cKit+), endothelial progenitor cells (EPCs, Lin−, CD34+, Flk+), and stromal progenitor cells (SPCs, Lin−, CD29+, CD105+) in peripheral blood mononuclear cells (PBMCs) were analyzed simultaneously by flow cytometry. Mobilized HPCs, EPCs and SPCs in PBMC were also measured by colony-forming unit (CFU) assay in progenitor-specific media. Three groups of mice received vehicle, GT3 and GT3 plus AMD3100, a receptor antagonist used to enhance mobilization. GT3 induced significant mobilization of all three progenitor cell types compared to vehicle in peripheral blood; AMD3100 enhanced GT3-induced mobilization even further. Mobilization of progenitor cells in peripheral blood by GT3 indicates that GT3 can be used as an alternative to G-CSF and VGEF to mobilize HPCs and EPCs.

The aim of the present study was to assess recovery from hematopoietic and gastrointestinal damage by Ex-RAD®, also known as ON01210.Na (4-carboxystyryl-4-chlorobenzylsulfone, sodium salt), after total body radiation. In our previous study, we reported that Ex-RAD, a small-molecule radioprotectant, enhances survival of mice exposed to gamma radiation, and prevents radiation-induced apoptosis as measured by the inhibition of radiation-induced protein 53 (p53) expression in cultured cells. We have expanded this study to determine best effective dose, dose-reduction factor (DRF), hematological and gastrointestinal protection, and in vivo inhibition of p53 signaling. A total of 500 mg/kg of Ex-RAD administered at 24 h and 15 min before radiation resulted in a DRF of 1.16. Ex-RAD ameliorated radiation-induced hematopoietic damage as monitored by the accelerated recovery of peripheral blood cells, and protection of granulocyte macrophage colony-forming units (GM-CFU) in bone marrow. Western blot analysis on spleen indicated that Ex-RAD treatment inhibited p53 phosphorylation. Ex-RAD treatment reduces terminal deoxynucleotidyl transferase mediated dUTP nick end labeling assay (TUNEL)-positive cells in jejunum compared with vehicle-treated mice after radiation injury. Finally, Ex-RAD preserved intestinal crypt cells compared with the vehicle control at 13 and 14 Gy. The results demonstrated that Ex-RAD ameliorates radiation-induced peripheral blood cell depletion, promotes bone marrow recovery, reduces p53 signaling in spleen and protects intestine from radiation injury.

Radiation-induced microvascular injury plays an important role in the mechanisms of acute, as well as chronic normal tissue radiation toxicities. There is currently a growing body of evidence suggesting that depletion of the nitric oxide synthase (NOS) cofactor, 5,6,7,8-tetrahydrobiopterin (BH4) is involved in the pathogenesis of endothelial dysfunction in many disorders. BH4 is an essential cofactor for all NOS enzymes, which, in the presence of adequate amounts of BH4, produce mainly nitric oxide (NO). Under conditions of BH4 deficiency, however, NOS is in the "uncoupled" state and production shifts to highly reactive oxygen radicals, superoxide, and peroxynitrite, at the expense of NO. Excessive oxidative stress, which occurs after exposure to ionizing radiation, reduces the bioavailability of BH4 because of rapid oxidation to 7,8-dihydrobiopterin (7,8-BH2). Free radical-induced BH4 insufficiency may thus further increase oxidative stress locally, inhibit beneficial NO-dependent endothelial processes, and contribute to the development of endothelial dysfunction. Given that BH4 depletion and subsequent endothelial NOS uncoupling appear to play a major role in the pathogenesis of endothelial dysfunction in a number of disease processes, there is substantial reason to believe that

Among the eight naturally occurring vitamin E analogs, γ-tocotrienol (GT3) is a particularly potent radioprophylactic agent in vivo. Moreover, GT3 protects endothelial cells from radiation injury not only by virtue of its antioxidant properties but also by inhibition of 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase and by improving the availability of the nitric oxide synthase cofactor tetrahydrobiopterin. Nevertheless, the precise mechanisms underlying the superior radioprotective properties of GT3 compared with other tocols are not known. This study, therefore, examined the differences in gene expression profiles between GT3 and its tocopherol counterpart, γ-tocopherol, as well as between GT3 and α-tocopherol in human endothelial cells. Cells were treated with vehicle or the appropriate tocol for 24 h, after which total RNA was isolated and genome-wide gene expression profiles were obtained using the Illumina platform. GT3 was far more potent in inducing gene-expression changes than α-tocopherol or γ-tocopherol. In particular, GT3 induced multiple changes in pathways known to be of importance in the cellular response to radiation exposure. Affected GO functional clusters included response to oxidative stress, response to DNA damage stimuli, cell cycle phase, regulation of cell death, regulation of cell proliferation, hematopoiesis, and blood vessel development. These results form the basis for further studies to determine the exact importance of differentially affected GO functional clusters in endothelial radioprotection by GT3.

Gamma-tocotrienol (GT3), a promising radioprotectant, is shown to protect CD2F1 mice from radiation-induced neutropenia and thrombocytopenia when given 24h prior to total-body irradiation. GT3 also is shown to increase white blood cells (WBC) and absolute neutrophil counts (ANC) transiently in peripheral blood. We hypothesized that increases in WBC and ANC may involve stimulation of hematopoiesis possibly by cytokines and growth factors. To evaluate the effects of GT3 on hematopoietic system, we measured various cytokines, chemokines and growth factors by cytokine array and Bio-Plex assays. Both showed strong induction of various cytokines and chemokines. GT3 treatment resulted in significant increases in G-CSF, IL-1α, IL-1β, IL-6, IL-12p70, IL-17, MIP-1α, and KC levels. G-CSF levels increased markedly within 12–24h after administration (5441pg/ml in GT3-treated groups compared to 17pg/ml in vehicle control). Most of these cytokine levels were elevated in the presence or absence of radiation. Time-course analysis of G-CSF and IL-6 induction showed that both cytokines were induced transiently after GT3 administration, and returned to normal levels by 48h post-administration. For G-CSF, the peak was observed between 12 and 24h post-administration of GT3; however, the highest levels of IL-6 were obtained between 6 and 12h. These results demonstrate that GT3 induced high levels of G-CSF and other inflammatory cytokines and chemokines within 24h after administration. Survival studies reported showed that the most efficacious time for administering GT3 was 24h prior to irradiation, possibly because it induced key hematopoietic cytokines in that time window. These results also suggest a possible role of GT3-induced G-CSF stimulation in protecting mice from radiation-induced neutropenia and thrombocytopenia.

A high-strength Ti – 6% Al – 4% V titanium alloy is studied after warm rolling at 650 – 750°C in several passes. Tensile mechanical tests are used to determine the rupture strength, the yield strength, and the elongation. The microstructure of the rolled alloy is investigated. Warm rolling is shown to be effective for forming superfine grains in the Ti – 6% Al – 4% V alloy and raising considerably the strength characteristics without lowering the ductility.

High-strength bulk ultrafine-grained magnesium alloy AZ31 bars were successfully developed in this study using multi-pass warm rolling. AZ31 bars of 12 mm diameter and several meters length were produced by multi-pass warm rolling of 45 ×45 mm forged blocks at 250°C and 300°C. The yield strength of warm-rolled rods doubled without any apparent loss of elongation. X-ray diffraction analysis revealed that the fractions of the basal planes oriented along and perpendicular to the rolling directions are nearly similar in intensity levels, indicating no strong texture along the rolling direction. The drastic improvement in mechanical properties is attributed to the ultrafine-grained microstructure in the warm-rolled specimens, whereas the absence of the loss of elongation is attributed to the fewer number of twins.

Hemangiopericytoma is a vascular tumor which comprises only 1% of all vascular tumors. The frequency of occurrence in the head and neck accounts for about 16-33% of all hemangiopericytomas. In this paper we discuss the surgical management, the difficulties in decision-making and treatment-planning in a case of a maxillary tumor in a five-year-old boy with a two-year follow-up. A five-year-old boy presented with a large unilateral maxillary tumor with nasal obstruction. Computed tomography revealed a heterogeneous mass completely occupying the right maxillary sinus and displacing the lateral wall of the nose and nasal septum. The lesion was diagnosed as hemangiopericytoma after histopathological confirmation. The option of surgical resection (total maxillectomy) was carried out after evaluating the available literature. Various treatment modalities like surgery, chemotherapy and radiotherapy were taken into consideration as the tumor has an aggressive nature. Due to the inadequate literature on definitive treatment options for these types of tumors, there was difficulty in arriving at a protocol-based treatment plan.

Pure aluminum reinforced with carbon nanotube (CNT) composites have been prepared by high energy attritor milling up to 48hrs. Differential Scanning Calorimetry (DSC) has been carried out to investigate apparent activation energy and order of the reaction between carbon nanotubes and aluminum by Kissinger equation and Crane equation under non-isothermal conditions. The DSC results clearly reveal that an exothermic reaction occurs before the melting of aluminum. The effect of milling time on the initiation of this exothermic reaction has been studied. The peak temperature of the reaction of carbon nanotubes and aluminum is found to depend on the heating rate during the continuous heating. Apparent activation energy was found to get doubled after milling for 36hrs compared to 24hrs milled samples. The mechanism of the reaction kinetics which depends on reaction order is instantaneous nucleation and one dimensional growth for both samples. Formation of Al4C3 was confirmed by X-ray diffraction (XRD) of as-milled powders and after performing DSC of the milled powders.

The biological functions of vitamin E related compounds have been of interest in biomedical research for several decades. Among those compounds, alpha-, beta-, delta-, and gamma-tocopherols and their oxidation products, alpha-, beta-, delta-, gamma-tocopherylquinone and their analogs alpha-TQo, gamma-TQo, TMC20 and TMC40 were recently shown to inhibit the mitochondrial cytochrome bc1 complex. In this investigation the effects of the structural variation on the inhibition of the mitochondrial cytochrome bc1 complex were analyzed using Comparative Molecular Field Analysis (CoMFA). CoMFA performed using steric and electrostatic molecular fields produced a very good correlation. The best CoMFA models were obtained using the manual alignment of 12 compounds with 5 components (q(2)=0.589, SPRESS=0.515, r(2)=0.992, s=0.068 and F value=156.520). The resulting contour maps produced by the best CoMFA model were helpful in identifying the structural features required for the biological activity of compounds under study. These results would be helpful for predicting the activity of new compounds, and they could be used for guiding the design, synthesis and development of new and more effective agents.

Circulating citrulline originates almost exclusively from the small intestinal enterocytes in mammals and therefore is a potential biomarker of disease states affecting enterocyte mass including exposure to ionizing radiation. There is a need for a simple and rapid method for citrulline quantification in plasma. To achieve this goal, a high-throughput separation and tandem mass spectrometric detection strategy has been developed and validated in six different species. HILIC separation was achieved on a 1.7 μm fused-core Diol column using an acidic acetonitrile/water gradient. A surrogate analyte (citrulline stable isotope) was used to determine the lower-limit-of-quantitation, extraction recovery, and matrix ion effects. Mass spectrometric detection was achieved in the multiple reaction-monitoring mode using m/z 176 → 159, 177 → 160, and 181 → 164, for citrulline, citrulline+1, and citrulline+5, respectively. The retention time of citrulline and total chromatographic run time were 1.1 min and 2.5 min, respectively, while effectively eliminating matrix-ion effects and achieving baseline separation from the confounding amino acid arginine. Quantitation was precise (CV <4.3%), accurate (90–110%), and sensitive (lower-limit-of-quantitation; 0.125 μM) without interference from the confounding amino acid, arginine. The throughput of the method was enhanced by incorporation of a 96-well filter plate for final sample cleanup. The method was used to determine plasma citrulline in six different species and in mice treated with escalating doses of radiation. This simple, accurate and high-throughput (up to 200 samples/day) methodology provides the first quantitative assay to meet the growing demand for a rapid and simple citrulline assay with high sensitivity.

Induced pluripotent stem (iPS) cells are derived from reprogrammed somatic cells and are similar to embryonic stem (ES) cells in morphology, gene/protein expression, and pluripotency. In this study, we explored the potential of iPS cells to differentiate into alveolar Type II (ATII)-like epithelial cells. Analysis using quantitative real time polymerase chain reaction and immunofluorescence staining showed that pulmonary surfactant proteins commonly expressed by ATII cells such as surfactant protein A (SPA), surfactant protein B (SPB), and surfactant protein C (SPC) were upregulated in the differentiated cells. Microphilopodia characteristics and lamellar bodies were observed by transmission electron microscopy and lipid deposits were verified by Nile Red and Periodic Acid Schiff staining. C3 complement protein, a specific feature of ATII cells, was present at high levels in culture supernatants demonstrating functionality of these cells in culture. These data show that the differentiated cells generated from iPS cells using a culture method developed previously (Rippon et al., 2006) are ATII-like cells. To further characterize these ATII-like cells, we tested whether they could undergo epithelial to mesenchymal transition (EMT) by exposure to drugs that induce lung fibrosis in mice, such as bleomycin, and the combination of transforming growth factor beta1 (TGF(b1)) and epidermal growth factor (EGF). When the ATII-like cells were exposed to either bleomycin or a TGF(b1)-EGF cocktail, they underwent phenotypic changes including acquisition of a mesenchymal/fibroblastic morphology, upregulation of mesenchymal markers (Col1, Vim, a-Sma, and S100A4), and downregulation of surfactant proteins and E-cadherin. We have shown that ATII-like cells can be derived from skin fibroblasts and that they respond to fibrotic stimuli. These cells provide a valuable tool for screening of agents that can potentially ameliorate or prevent diseases involving lung fibrosis.