Γ-irradiation Dose Research Articles

Electric properties of composites filled with disperse oxides

The electrical properties of polymer composition materials with dispersed fillers have been investigated. The dependence of the conductivity on the concentration, the absorbed dose of γ-irradiation, and the temperature has been studied. The close connection of the electroconductivity of the compositions and the chemical nature of the fillers is shown. It has been found that the change caused by the interaction of the γ-irradiation with the fillers can considerably increase the electroconductivity of the polymeric composition.

Transgenerational changes in somatic and germ line genetic integrity of first-generation offspring derived from the DNA damaged sperm

To report a more quantitative approach to study the influence of varying levels of sperm DNA damage on transgenerational changes in genomic instability in a mouse model. Experimental prospective study. Embryology research laboratory. Swiss albino mice. The sperm DNA damage was induced by different doses of gamma-irradiation to male mice followed by mating with healthy female mice. Genomic integrity in embryos, fetus, and spermatozoa of F1 mice derived from the DNA-damaged sperm. The transgenerational changes in genetic integrity were attributed by a dose-dependent increase in the frequency of micronuclei in preimplantation embryos and a concomitant increase in genomic instability in fetal liver cells and sperm chromatin modifications in F1 males. A strong positive correlation was observed between the extent of sperm DNA damage and somatic and germ-line genomic instability. Sperm-mediated transgenerational genomic instability is dependent on the amount of DNA damage present in the sire's sperm at the time of fertilization.

Therapeutic Potential of Green Tea Extract and Low Doses of γ-Irradiation on Diabetic Nephropathy of Rats

Introduction: Diabetic nephropathy is one of the most frequent and serious complications of diabetes mellitus. This study was designed to evaluate the effect of green tea (GT) extract and low doses of 0.5 Gy γ-radiation (R) on diabetic nephropathy (DN) of rats. Materials and methods: Male Swiss albino rats were used in this study. DN was induced in rats using streptozotocin (45 mg/kg body weight). The rats were divided into five groups DN, DN+R, DN+GT, DN+GT+R and a sham treatment control group. Throughout the experimental period (3and 6 weeks) animals body weight, glucose and insulin levels were evaluated. Kidney functions assay (serum urea and creatinin) were recorded. Histopathological observations in kidney tissue, DNA and glycogen intensity were also detected. Results: Diabetic rats exhibited many symptoms including loss of body weight, increase in blood glucose level and decrease in serum insulin levels. Increase in serum urea and creatinin levels. Diabetic kidney showed a moderate renal damage, multifocal clarifications and vacuolations. Carbohydrates intensity showed a significant increase and DNA intensity showed many alterations. Improvements in glomerular and tubulointerstitial lesions were demonstrated in the diabetic rat group exposed to low doses of γ-radiation or supplemented by green tea either alone or combined in addition to amelioration in glucose, insulin urea and creatinin levels. Conclusion: The present study demonstrates the efficacy of low doses of γ- radiation and in reducing diabetes-induced functional and histological alterations in the kidneys. The longterm control of blood glucose levels using low doses of γ-radiation or green tea either alone or combined could prevent the progression of diabetes mellitus, and therefore, nephropathy could be prevented.

Radiation polymerization of 2-acrylamido-2-methylpropanesulfonic acid in aqueous solutions

The dependence of the yield of polymer and its molecular mass on the absorbed dose of γ-irradiation of a 0.8 M 2-acrylamido-2-methylpropanesulfonic acid aqueous solution was determined, as well as the gel fraction of the polymer produced. The feasibility of obtaining a crosslinked polymer via radiation polymerization of 2-acrylamido-2-methylpropanesulfonic acid in the presence of N,N′-methylenebisacrylamide admixtures was shown. It was found that the maximal degree of crosslinking is reached at a dose on the order of 20 kGy and the maximal water uptake (1150 g/g) is achieved at a dose of 1.25 kGy.

Therapeutic Potential of Green Tea Extract and Low Doses of γ-Irradiation on Diabetic Nephropathy of Rats

Introduction: Diabetic nephropathy is one of the most frequent and serious complications of diabetes mellitus. This study was designed to evaluate the effect of green tea (GT) extract and low doses of 0.5 Gy γ-radiation (R) on diabetic nephropathy (DN) of rats. Materials and methods: Male Swiss albino rats were used in this study. DN was induced in rats using streptozotocin (45 mg/kg body weight). The rats were divided into five groups DN, DN+R, DN+GT, DN+GT+R and a sham treatment control group. Throughout the experimental period (3and 6 weeks) animals body weight, glucose and insulin levels were evaluated. Kidney functions assay (serum urea and creatinin) were recorded. Histopathological observations in kidney tissue, DNA and glycogen intensity were also detected. Results: Diabetic rats exhibited many symptoms including loss of body weight, increase in blood glucose level and decrease in serum insulin levels. Increase in serum urea and creatinin levels. Diabetic kidney showed a moderate renal damage, multifocal clarifications and vacuolations. Carbohydrates intensity showed a significant increase and DNA intensity showed many alterations. Improvements in glomerular and tubulointerstitial lesions were demonstrated in the diabetic rat group exposed to low doses of γ-radiation or supplemented by green tea either alone or combined in addition to amelioration in glucose, insulin urea and creatinin levels. Conclusion: The present study demonstrates the efficacy of low doses of γ- radiation and in reducing diabetes-induced functional and histological alterations in the kidneys. The longterm control of blood glucose levels using low doses of γ-radiation or green tea either alone or combined could prevent the progression of diabetes mellitus, and therefore, nephropathy could be prevented.

Influence of γ-irradiation on optical properties of manganese phthalocyanine thin films

The optical absorption of thermally evaporated MnPc thin film has been studied in the UV–vis region. The absorption spectra for the as-deposited and irradiated films showed two well-defined absorption bands of phthalocyanine molecule, namely the Q-band and Soret band (B). The optical properties of thermally evaporated manganese phthalocyanine thin films were characterized using spectrophotometric measurements of transmittance and reflectance at normal incidence of light in the wavelengths range 200–2500 nm. The refractive index ( n) and the absorption index ( k) were calculated. The effects of γ-irradiation on the optical properties were investigated for dosimetry applications. The values of the optical band gap E opt, the transport gap and the dispersion parameters for as-deposited and irradiated films with different doses of γ-irradiation were also estimated and discussed.

Effects of γ-irradiation on antioxidant activity in soybean seeds

AbstractThere are some reports that low doses of γ-irradiation could induce antioxidant activities in plant material, including soybean. Irradiation, required for the inactivation of some pathogens and induction of mutations, may have adverse effects on sensorial, nutritional and antioxidant qualities. The effects of different γ-irradiation doses (100–200 Gy) on antioxidant properties of soybean seeds was investigated. In this study, we report the results obtained by analysis of antioxidant enzyme activities, reduced glutathione, malonyldialdehyde (MDA) and hydroxyl (HO−) radical quantities, soluble protein content, and total antioxidant activity in irradiated soybean seeds. Antioxidant enzyme activities were affected due to high irradiation intensity. Significant changes of total antioxidant activity and MDA and HO.quantities were observed only under the highest irradiation dose, with a 15.7% reduction in total antioxidant activity, MDA quantity increase of 21.6%, and HO− radical quantity increase of 79.3% compared to the non-irradiated control. The total soluble protein content increased slightly.

Design and influence of γ-irradiation on the biopharmaceutical properties of nanoparticles containing an antigenic complex from Brucella ovis

Despite vaccination campaigns, brucellosis is still one of the most common bacterial zoonosis in the world. This work describes the development of a novel formulation strategy to the delivery of the Brucella ovis antigenic extract (HS) into ovine mucosal surfaces. Thus, HS was entrapped in conventional and mannosylated poly(anhydride) nanoparticles by the solvent displacement method, and the resulting nanosystems were γ-irradiated to accomplish the sterilization required for the ophthalmic administration route. Sterilization, at either 10 kGy or 25 kGy, did not modify the size, morphology and antigen content of the nanoparticles. Similarly, the integrity and antigenicity of the entrapped antigen were not affected by γ-irradiation. The 25 kGy γ-irradiation dose seemed to influence negatively the HS release from the carriers. However, and in accordance with the Pearson's correlation, all the release patterns followed a similar tendency. Furthermore, the stability of the vaccine systems on lachrymal and nasal ovine fluids, showed that γ-irradiation had no significant effects on the vaccine systems. Since all the vaccine systems accomplished the pharmacopoeial biological tests required for γ-irradiation doses under 25 kGy, these results are highly suggestive for the use of HS loaded poly(anhydride) nanoparticles as an efficient vaccine delivery system for brucellosis immunoprophylaxis, especially for ophthalmic administration.

The effects of a silane coupling agent on properties of rice husk-filled maleic acid anhydride compatibilized natural rubber/low-density polyethylene blend

Blends of natural rubber and low-density polyethylene were prepared in different weight compositions in presence of dicumyl peroxide and maleic acid anhydride. The effects of rice husk (RH) content and a silane coupling agent, that is, 3-aminopropyl triethoxy silane (3-APE, 1 wt% of filler content) on the physicomechanical properties and mass swell of the tested blend were investigated. The incorporation of untreated RH into the blend improved Young’s modulus, hardness but decreased tensile strength, elongation at break, impact strength, and mass swell. Incorporation of 3-APE has produced composite with improved tensile strength, Young’s modulus, hardness and impact strength with a sharp decrease in elongation, and better mass swell in comparison with untreated one. The effect of γ-irradiation doses on retained physicomechanical properties of RH (30 phr) filled blend samples before and after silane treatment was investigated at ambient temperature. The efficiency of silanized RH (30 phr) was also evaluated by the studies of the surface morphology (scanning electron microscopy) and thermal properties (thermal gravimetric analysis and thermal mechanical analysis).

Effect of γ-irradiation on the physicochemical and sensory properties of cashew nuts (Anacardium occidentale L.)

The present study evaluated cashew nuts' quality as a function of γ-irradiation dose in order to determine dose levels causing minimal undesirable changes to the product. Physicochemical (colour, peroxide value, hexanal content, fatty acid composition, volatile compounds) and sensory (colour, texture, odor, taste) properties of cashew nuts were determined after irradiation at doses up to 7 kGy. Results showed a five-fold increase in peroxide value (PV) and a two-fold increase in hexanal content after irradiation at a dose of 7 kGy. Of the fatty acids determined, stearic acid concentration increased while oleic acid decreased with irradiation dose. PUFA were unaffected by irradiation. Volatile compounds such as aldehydes, ketones and alcohols increased after irradiation indicating enhanced lipid oxidation. Colour parameter a∗ increased (p < 0.05) at doses >3 kGy while colour parameters L∗ and b∗ remained unaffected by irradiation. Sensory analysis showed that cashew nuts remained organoleptically acceptable at doses <3 kGy.

Effect of gamma radiation on antioxidant enzymes and G 6 PDH activities in Vicia faba plants

The effect of gamma irradiation on Vicia faba L. plants was investigated by exposing dry seeds to doses ranging from 0 to 100 Gray (Gy) and studying the activities and isozyme patterns of the key enzymes involved in oxidative stress defence, such as superoxide dismutases (SOD, EC 1.15.1.1), catalases (CAT, EC 1.11.1.6), peroxidases (POX, EC 1.11.1.7), ascorbate peroxidases (APOX, EC 1.11.1.11), monodehydroascorbate reductase (MDHAR, EC 1.6.5.4) and glutathione reductase (GR, EC 1.6.4.2), as well as the activity of an enzyme involved in a specific intermediary metabolic pathway, glucose-6-phosphate dehydrogenase (G 6 PDH, EC 1.1.1.49). The H 2 O 2 contents of faba bean leaves were also measured. None of the γ-irradiation doses used (0–100 Gy) had any effect on the activity of MDHAR, but they increased the enzyme activities of GR, APOX, SOD and G 6 PDH. Gamma rays at 20 Gy decreased the H 2 O 2 content, but the 100 Gy dose significantly increased the H 2 O 2 content compared with the non-irradiated plants. The results implied that the isozymes of SOD, CAT and POX present in faba bean cells growing in the presence of 0–15 Gy γ-irradiation are required to remove the reactive oxygen species (ROS) produced during normal, physiological processes. When the dose of γ-irradiation is ≥20 Gy, the level of ROS (produced indirectly by γ-irradiation) becomes too high to be dealt with by the existing antioxidant isozymes. The present research shows for the first time that the switch between the physiological oxidative response and a stress-related one occurs within a very narrow range of stress factor intensities, i.e. γ-irradiation doses. In the present study, this change took place between 15 and 20 Gy. Further investigations, using molecular biology techniques will be needed to determine the mechanisms involved in enzyme induction under ionizing conditions in order to evaluate changes in the gametic genomes at two possible levels: (i) the structural level, for studying mutations occurring in the DNA, and (ii) the functional level, by studying differential genetic expression between irradiated and non-irradiated plants.

The influence of γ- and UV-radiation dose on the buildup and decay of paramagnetic centers in solid hydrogen cyanide

A decrease in the concentration of paramagnetic centers (PMCs) stabilized at 77 K in crystalline hydrogen cyanide was observed when ionizing radiation doses exceeded 3000 kGy. It was assumed that the decrease is due to a change in the physical properties of the matrix as a result of its deformation, loosening, amorphization, and formation of metastable structures. The decay of the PMCs with an increase in temperature of the irradiated samples depends on the dose and type (UV, γ) of the radiation. The higher the dose of preliminary γ-irradiation, the lower the decay temperature. In UV-irradiated HCN, the paramagnetic centers that occur in the thin photolyzed layer are more stable, since they are localized at defect sites of the crystalline matrix, which hinder the migration of free valence.

Enhancing the transport properties of polycrystalline MgB2 superconductors

MgB2 polycrystalline superconducting specimens were irradiated with 10 MR and 20 MR doses of γ-rays. An increase in the normal state resistance and a broadening of the resistive transition to the superconducting state were observed with increasing γ-irradiation dose within the temperature range of 28 –31 K. The change in the critical temperature, Tc was found to be insignificant after irradiation. The critical current density, Jc was found to be enhanced almost at all temperatures after irradiation. The enhancement of Jc was found to be linear with the irradiation dose at all temperatures. These results are explained by the effects of γ-rays and temperature on the migration of MgO impurities into the grains and the oxygen segregation in the grain boundaries.

Effect of γ-dose rate on crystallinity and morphological changes of γ-sterilized biomedical polypropylene

The present work is aimed to study the changes in crystallinity and morphology of biomedical polyolefins after γ-sterilization. The isotactic polypropylene (iPP) films were sterilized by γ-radiation and the changes were characterized by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and atomic force microscopy (AFM) techniques. The effect of dose rate on crystallinity changes also was focused. It was found that crystallinity and morphology significantly changed with γ-irradiation. There was an increase in crystallinity up to 10 kGy accompanied with decrease in viscosity and mechanical properties. The changes in crystallinity mainly depend on γ-irradiation dose and dose rate. The rise in crystallinity was attributed to chain scission and forming new perfect lamellae. However, the reduction was accompanied by occurrence of γ- and β-phases and crosslinking. Possible explanations for transitions in phases are also discussed based on our results.

How does γ-irradiation influence the phase transition of α-NiMoO 4?

An attempt has been made to stabilize the high temperature β-NiMoO 4 phase which is catalytically more selective in oxidative dehydrogenation of alkanes at room temperature through irradiation by γ-rays. Different samples of stoichiomertic α-NiMoO 4 were subjected to different doses of γ-irradiation in the range of 50–500 kGy. The effect of γ-irradiation on the α- to β-NiMoO 4 transition temperature was studied using differential thermal analysis (DTA) technique with controlled rate of heating and cooling. The formation of β-NiMoO 4 phase was investigated by means of XRD and FT-IR techniques. The catalytic performance of the resulting catalyst samples in the oxidative dehydrogenation of cyclohexane at 500 °C was investigated. The DTA investigation revealed that γ-irradiation effectively lowers the temperature of the α → β transition in NiMoO 4 but did not affect the temperature of β-to-α return transition. A new peak characteristic of β-phase was detected at 2 θ = 26.3° in the XRD patterns of γ-irradiated samples. FT-IR analysis also confirmed the formation of β-NiMoO 4 where a new band characteristic of β-phase was observed at 879 cm −1 in the spectra of these samples. In view of the XRD results, the observed change in the α- to β-NiMoO 4 transition temperature was attributed to the fact that radiation induced a strain in the α-NiMoO 4 crystals. On the other hand, catalytic activity results indicated that γ-irradiated nickel molybdate catalysts showed a high selectivity towards cyclohexene at isoconversion (5%) in comparison with that of unirradiated parent α-NiMoO 4.

Effect of combining anti-epidermal growth factor receptor antibody C225 and radiation on DU145 prostate cancer

The epidermal growth factor receptor (EGFR) network has rich targets for prostate cancer killing. Herein we evaluated the effects of combining the EGFR inhibition and radiation on DU145 prostate cancer. We treated DU145 prostate cancer cells with various doses of anti-EGFR antibody (C225) and gamma-irradiation (RAD). The effects of the treatment on cell viability and growth were assessed with cell counting, XTT and clonogenic assays. In vivo treatment effects were assessed using a subcutaneous tumor xenograft in mice. Cell cycle distribution and progression were assessed with flow cytometry. The apoptotic components of cell death were quantified using Annexin-V binding assays. The results demonstrated that when combined with radiation, C225 augmented the inhibition of cell viability and growth in the DU145 cell line and EGFR inhibition appeared to have some interaction with RAD. C225 inhibited the growth of implanted DU145 tumors and increased the efficacy of radiation treatment. Flow cytometric analysis suggested that mostly necrotic cell death resulted from the EGFR inhibition or irradiation, although there may be some apoptosis. We drew the conclusion that the inhibition of EGFR augments the radiation killing of DU145 prostate cancer via a combination of cytostatic, necrotic and apoptotic mechanisms.

Effect of 60Co γ-irradiation on postharvest quality and selected enzyme activities of Pleurotus nebrodensis

Freshly harvested Pleurotus nebrodensis fruit bodies were exposed to four different doses (0.8–2.0 kGy) of 60Co γ-irradiation and various physiological changes associated with postharvest deterioration, as well as the activities of selected enzymes (proteinase, polyphenoloxidase, superoxide dismutase, catalase) thought to play a role in the process of deterioration, were monitored during 22 days of subsequent storage at 4 °C and 65–70% relative humidity. An irradiation dose of 1.2 kGy significantly delayed (by 6–9 days) the onset of fruit body softening, splitting and browning compared with non-irradiated controls and test samples subjected to lower or higher irradiation doses. Irradiation with 1.2 and 1.6 kGy also had a positive effect on other indicators of mushroom tissue senescence, resulting in smaller decreases in soluble protein levels and more protracted increases in proteinase activity. Peak levels of polyphenoloxidase activity, widely recognized as causing postharvest browning of mushroom tissue, were also significantly lower ( P < 0.05) in fruit bodies exposed to 1.2 kGy compared with non-irradiated controls. Our data increase our understanding of the effects of γ-irradiation on the biochemical changes associated with postharvest deterioration in P. nebrodensis, and improve the prospects of more targeted strategies for extending the shelf life of both this and other mushrooms.

Purported nanobacteria in human blood as calcium carbonate nanoparticles

Recent evidence suggests a role for nanobacteria in a growing number of human diseases, including renal stone formation, cardiovascular diseases, and cancer. This large body of research studies promotes the view that nanobacteria are not only alive but that they are associated with disease pathogenesis. However, it is still unclear whether they represent novel life forms, overlooked nanometer-size bacteria, or some other primitive self-replicating microorganisms. Here, we report that CaCO(3) precipitates prepared in vitro are remarkably similar to purported nanobacteria in terms of their uniformly sized, membrane-delineated vesicular shapes, with cellular division-like formations and aggregations in the form of colonies. The gradual appearance of nanobacteria-like particles in incubated human serum as well as the changes seen with their size and shape can be influenced and explained by introducing varying levels of CO(2) and NaHCO(3) as well as other conditions known to influence the precipitation of CaCO(3). Western blotting reveals that the monoclonal antibodies, claimed to be specific for nanobacteria, react in fact with serum albumin. Furthermore, nanobacteria-like particles obtained from human blood are able to withstand high doses of gamma-irradiation up to 30 kGy, and no bacterial DNA is found by performing broad-range PCR amplifications. Collectively, our results provide a more plausible abiotic explanation for the unusual properties of purported nanobacteria.

Influence of heat treatment andγ-irradiation on the optical properties of methylene blue trihydrate thin films

Structural and optical properties of thermally evaporated methylene blue trihydrate thin films up to a film thickness of 165 nm have been investigated. The lattice constants and the crystallite size were calculated. The optical parameters were obtained using spectrophotometric measurements of the transmittance and reflectance at normal incidence of light in the wavelengths range 200–2500 nm. Below the absorption edge, subgap absorption in the energy range 0.75–1.4 eV was observed and interpreted in terms of defect states induced absorption phenomena and act as deep traps for charge carriers. The type of optical transition was found to be an indirect allowed transition. The values of the optical gap Eopt, the transport gap Et, the exciton binding energy EB, the Urbach's energy Eu and the dispersion parameters for as-deposited, annealed and irradiated films with different doses of γ-irradiation were estimated and discussed their influenced by heat treatment and irradiation.

Study of polymer-piezoceramic composites by the radio-thermo-luminescence method

In this work, the features of the dependence of radiothermoluminescence (RTL), charge stabilization, change of the temperature of structural β-and γ-transitions on the dose of γ-irradiation and degree of filling Φ of composites based on high-density polyethylene (HDPE) and piezoceramic fillers of the PKR-3M type are investigated. It is shown that the dependences of thermoluminescence intensity of the filling degree J(Φ) are characterized by extrema at the filler content as high as 5 vol % and a dose D = 20−30 kGy. It is shown that γadiation at defined doses leads to inhibition of the process of β-relaxation of HDPE in the composition, which can be associated with the formation of new trapping centers of excess charges of electrets.