Gy Irradiated Samples Research Articles

Evaluation of structural behaviour, radioluminescence, Judd-Ofelt analysis and thermoluminescence kinetic parameters of Eu3+ doped TTB–type lead metaniobate phosphor

In this study, the structural and spectroscopic properties of orthorhombic PbNb2O6 doped with different concentrations of Eu3+ were studied. Interestingly, XRD analysis of undoped PbNb2O6 showed rhombohedral phase while Eu3+ doped structures exhibited an orthorhombic phase at 1250 °C. This difference was also observed in the morphology and composition of grains by SEM-EDS analysis. PL and RL emissions occurred between 550 and 850 nm owing to the 4f–4f transitions of Eu3+. The Judd-Ofelt theory was applied to the experimental data for determination of the Judd-Ofelt parameters (Ω2, Ω4), radiative transition rates (Ar) and radiative lifetimes (τr). TL glow curves were monitored by the peaks of 98 and 250 °C while emission increased up to 6 mol%. TL emission of 6 mol% phosphor depending on X-ray irradiation dose exhibited the highest intensity for 1200 Gy and appeared new peaks. Moreover, the TL emission of phosphor showed a linear relation with X-ray irradiation. The deconvolution peaks of 1200 Gy irradiated samples were determined by the CGCD method. Kinetic data of first peak (98 °C) depending on the dose increase were calculated by the PS method.

RABiT-II: A Fully-Automated Micronucleus Assay System with Shortened Time to Result.

In this work, we describe a fully automated cytokinesis-block micronucleus (CBMN) assay with a significantly shortened time to result, motivated by the need for rapid high-throughput biodosimetric estimation of radiation doses from small-volume human blood samples. The Rapid Automated Biodosimetry Tool (RABiT-II) currently consists of two commercial automated systems: a PerkinElmer cell::explorer Workstation and a GE Healthcare IN Cell Analyzer 2000 Imager. Blood samples (30 μl) from eight healthy volunteers were gamma-ray irradiated ex vivo with 0 (control), 0.5, 1.5, 2.5, 3.5 or 4.5 Gy and processed with full automation in 96-well plates on the RABiT-II system. The total cell culture time was 54 h and total assay time was 3 days. DAPI-stained fixed samples were imaged on an IN Cell Analyzer 2000 with fully-automated image analysis using the GE Healthcare IN Cell Developer Toolbox version 1.9. A CBMN dose-response calibration curve was established, after which the capability of the system to predict known doses was assessed. Various radiation doses for irradiated samples from two donors were estimated within 20% of the true dose (±0.5 Gy below 2 Gy) in 97% of the samples, with the doses in some 5 Gy irradiated samples being underestimated by up to 25%. In summary, the findings from this work demonstrate that the accelerated CBMN assay can be automated in a high-throughput format, using commercial biotech robotic systems, in 96-well plates, providing a rapid and reliable bioassay for radiation exposure.

Influence of radiation processing of grapes on wine quality

Abstract Grapes (Var. Shiraz and Cabernet) were subjected to radiation processing (up to 2 kGy) and wines were prepared and matured (4 months, 15 °C). The wines were analyzed for chromatic characteristics, total anthocyanin (TA), phenolic (TP) and total antioxidant (TAC) content. Aroma of wines was analyzed by GC/MS and sensory analysis was carried out using descriptive analysis. TA, TP and TAC were 77, 31 and 37 percent higher for irradiated (1500 Gy) Cabernet wines, while irradiated Shiraz wines demonstrated 47, 18 and 19 percent higher TA, TP and TAC, respectively. HPLC-DAD analysis revealed that radiation processing of grapes resulted in increased extraction of phenolic constituents in wine with no qualitative changes. No major radiation induced changes were observed in aroma constituents of wine. Sensory analysis revealed that 1500 Gy irradiated samples had higher fruity and berry notes. Thus, radiation processing of grapes resulted in wines with improved organoleptic and antioxidant properties.

Effects of low dose X‐ray irradiation on porcine articular cartilage explants

Ionizing radiation therapy is a crucial treatment for cancer, but can damage surrounding normal tissues. Damage to articular cartilage leading to arthropathy can occur at irradiated sites. It is unclear whether this response is due to damaging surrounding skeletal structures or direct effects on cartilage. In this study, we showed that irradiation with 2 Gy of X-rays causes a significant reduction in the stiffness of porcine explants 1 week post-irradiation. By using both microindentation and indentation-type atomic force microscopy, ionizing radiation reduces stiffness in both the superficial zone, and throughout the entire thickness of the tissue. Young's modulus values were 75% and 60% lower in 2 Gy irradiated samples when compared with controls using microindentation and nanoindentation, respectively. Glycosaminoglycans (GAGs) released into the culture media of irradiated samples was nearly 100% greater at 24 h after exposure. While collagen content in the tissue is similar between groups, GAG content is 55% lower in irradiated explants compared with controls 7 days after exposure. Therefore, the irradiated explants are unable to recover from the initial loss of GAGs by 1 week. This acute loss of GAGs is a likely contributor to the reduction in modulus seen after exposure to ionizing radiation.

Electron Spin Resonance Analyses of Grinding- and Radiation-Induced Signals in Raw and Refined Sugars

Irradiated food containing crystalline sugar may be identified using the electron spin resonance spectroscopy (ESR) in accordance with the European standard EN 13708 2001. The method is based upon the detection of sugar radicals induced by irradiation giving a typical dose-dependent spectrum. Grinding, a common industrial process, can also produce ESR signals. In this study, the grinding-induced ESR signals were investigated for their dependence on sugar purity, grinding time, particle size, and grinding method. The results were compared with radiation-induced ESR signals. The mechanical grinding, depending mainly on grinding time, provided clear signals comparable to radiation-induced signals. The specific ESR signal corresponding to sugar radical appeared at 1 min of mechanical grinding which became clearer with the increase in grinding time and sample purity. All sugar samples upon 6 min of mechanical grinding showed comparable results to ≥10 Gy-irradiated samples. Similar results with negligible differences were found using samples of different origins. The results elaborated the detection limits of sugar containing irradiated food based on ESR analysis.

SU‐E‐T‐06: Investigating in Vitro Gamma‐H2AX Response and Chromosome Damage in Human Lymphocytes and Lymphocyte Subsets for Biomarkers of Radiation Sensitivity

Purpose: To examine the in vitro gamma‐H2AX response in lymphocytes and lymphocyte subsets from patients who have shown severe radiosensitive response (severe late toxicity) in order to determine whether radiation responsive subsets would provide more specific markers for radiosensitivity. To concurrently examine cytogenetic endpoints as potential markers for radiosensitivity in addition to providing additional information about the mechanisms of radiosensitivity. Methods: Ten prostate cancer patients were identified with grade 3 Late Proctitis (RTOG/EORTC Late Radiation Morbidity Scoring Schema) along with twelve matched normal responding patients (Grade 0 Toxicity). These patients had been treated with dose escalated (76Gy) 3D Conformal Radiotherapy as part of an ongoing Phase III clinical trial. Peripheral blood samples were taken from each patient, irradiated with 250kV, 12.5mA x‐rays and examined for gamma‐H2AX response in lymphocytes, CD4+ and CD8+ T‐cells, and CD19+ B‐cells. A dose course experiment was conducted with 6 dose points ranging from 0 to 10 Gy, processed 1 hour after irradiation. The time response of gamma‐H2AX was also monitored, with 2 Gy irradiated samples being incubated for 7 time points ranging from 0 to 24 hours before processing. Samples were fixed stained with gamma‐HAX‐FITC, CD4‐PE, CD8‐APC and CD19‐PC7 before being analyzed by flow cytometry. Furthermore, 0 and 6 Gy irradiated blood samples were analyzed for chromosome aberrations and excess fragments per cell.Results: In a subset of the data for the radiosensitive population, the gamma‐H2AX response tended to be higher in the time course experiment. It was also found that, at 6 Gy, the number of excess fragments per cell in the radiosensitive population (1.65 +/− 0.29) was higher than in the normal population (2.20 +/− 0.27) (p‐value < 0.001) Conclusions: These preliminary results suggest the existence of potential for markers for predicting radiosensitivity which could be useful for tailoring radiotherapy treatments.

Radiation-induced bystander effect in healthy G 0 human lymphocytes: Biological and clinical significance

To study the bystander effects, G 0 human peripheral blood lymphocytes were X-irradiated with 0.1, 0.5 and 3 Gy. After 24 h, cell-free conditioned media from irradiated cultures were transferred to unexposed lymphocytes. Following 48 h of medium transfer, viability, induction of apoptosis, telomere shortening, reactive oxygen species (ROS) levels and micronuclei (after stimulation) were analyzed. A statistically significant decrement in cell viability, concomitant with the loss of mitochondrial membrane potential, telomere shortening, increases in hydrogen peroxide (H 2O 2) and superoxide anion (O 2 −) with depletion of intracellular glutathione (GSH) level, and higher frequencies of micronuclei, were observed in bystander lymphocytes incubated with medium from 0.5 and 3 Gy irradiated samples, compared to lymphocytes unexposed. Furthermore, no statistically significant difference between the response to 0.5 and 3 Gy of irradiation in bystander lymphocytes, was found. However, when lymphocytes were irradiated with 0.1 Gy, no bystander effect with regard to viability, apoptosis, telomere length, and micronuclei was observed, although a high production of ROS level persisted. Radiation in the presence of the radical scavenger dimethyl sulfoxide (DMSO) suppressed oxidative stress induced by 3 Gy of X-rays with the effective elimination of bystander effects, suggesting a correlation between ROS and bystander signal formation in irradiated cells. The data propose that bystander effect might be mostly due to the reactions of radiation induced free radicals on DNA, with the existence of a threshold at which the bystander signal is not operative (0.1 Gy dose of X-rays). Our results may have clinical implications for health risk associated with radiation exposure.

Single-dose irradiation followed by implant insertion in rat bone. An investigative study to find a critical level for osseointegration

Aim No general consensus exists regarding the ideal time to insert implants in bone after irradiation or how the various irradiation doses influence implant success. This study aims at investigating integration of implants in pre-irradiated rat bone and find a critical level doses that cause disturbed osseointegration. Materials and methods Single irradiation doses of 2, 5, 10, 20 and 30 Gy were given to one leg of adult rats 3 days prior to insertion of screw-shaped implants whereas the other leg served as a nonirradiated control. The follow up was 5 weeks. Bone implant contact (BIC) and bone area (BA) were measured on undecalcified cut and ground sections in the light microscope. The tissue quality was also examined in the light microscope. Results Doses of 5 and 10 Gy resulted in 25% higher contact values for the irradiated samples compared to non-irradiated controls. The most impaired integration occurred when doses of 20 Gy were given, revealing a 50% difference between the irradiated (25%) and the non irradiated samples (50%). The bone area demonstrated no major quantitative differences albeit the qualitative observations differed substantially being most pronounced in the 20 and 30 Gy irradiated samples. Conclusions The osseointegration was substantially impaired after radiation doses of 20 and 30 Gy. Quantitative data alone are insufficient to describe implant integration in situation like this. Qualitative observations are of utmost importance and require great attention. The importance of judging and describing various grades of tissue damage is complicated but necessary. Based on the results obtained in this study, full scale experiments are now ongoing.

Light and electron microscopy study of radioinduced injuries in rat cortex kidney vs. dose rate of irradiation

In order to describe radiation induced alterations of renal cell morphology, adult rats were whole-body exposed to 60-cobalt gamma rays at various doses (1, 2, or 4 Gy) and two dose rates (1 Gy/min or 1 Gy/h). 24 h or 48 h after irradiation, kidneys were take off and cortex fragments were fixed and embedded. Paraffin sections were used for light microscope study and TUNEL assay, and epon ones for conventional transmission electron microscope observations. Morphological changes in numerous tubules of irradiated samples were observed mainly in cells of proximal convoluted tubules (PCT) and not in distal ones (DCT), as nuclear and cytoplasm lesions. Epithelial cells containing round and small nucleus with homogenous condensed chromatin were detected in 1 Gy/min samples, which number increased with dose and post-irradiation time. Cells protuberances were seen in PCT lumen and identified as cellular proliferations. Damaged cells appeared TUNEL assay positives when compared to same serial histological cuts. Large tubular necrosis areas were seen only at 4 Gy dose, 1Gy/min dose rate and 48 h post-irradiation time that involved all tubules. Ultrastructural lesions were observed in cortex kidneys 24 h after irradiation at 2 and 4 Gy doses and 1 Gy/min dose rate, displaying all features of apoptotic process mainly in PCT isolated cells. Their appeared with dense cytoplasm that contains clusters of enlarged mitochondrias, numerous light vesicles and condensed heterogeneous chromatin within atypical shape nuclei. Others subcellular alterations of epithelial cells were seen only in 4 Gy-irradiated samples as brush border irregular microvilli. Some cellular fragments were detected inside the lumen of intact DCT containing recognizable organelles that we suppose to be apoptotic bodies of injured PCT cells. When compared to controls, glomeruli changes were induced at 1 Gy/h dose rate, 24 h after exposition for the two doses of irradiation as detachment of enlarged podocytes from basal membrane, hypertrophy of mesangial cells, damaged endothelial cells and vacuolization of the parietal leaflet.