[en] Platelet derived growth factor(PDGF)and platelet derived growth factor receptor(PDGFR) are abnormally synthesized following the autocrine growth activation in a number of malignant tumors. PDGF is a effective mitogen and chemical agent, PDGFR belongs to tyrosine kinase receptors. After binding with corresponding ligand, PDGFR is activated and lead to activate a series of downstream signal pathways and has resulted in many biological effects. PDGF and PDGFR signal pathway is associated with radiation resistance of tumor cells, and the mechanism is likely to be related to cell proliferation, suppressing apoptosis, and regulating cell cycle arrest. (authors)

[en] In order to understand the radiosensitizing effects on human glioma cells SHG44 using celecoxib, a cyclooxygenase (COX)-2 selective inhibitor, MTT assay was used to determine the effect of celecoxib on the cell growth, and Colony Formation assay, Reverse transcription-PCR assay were used to investigate the effect of celecoxib or combined with ⁶⁰Co γ-irradiation on cell colony formation rate and the levels of COX-2 mRNA expression. Experimental results suggested that the cytotoxicity of celecoxib enhanced along with the increment of drug's concentration. The celecoxib could inhibit colony formation in SHG44 cells. When combined with ⁶⁰Co γ-irradiation, COX-2 mRNA expression levels was lower than that of control, drug and irradiation group respectively. The study confirmed the radiosensitizing effects of this drug to human glioma cells SHG44, and it might be closely related to the COX-2 mRNA expression levels. (authors)

[en] Objective: To explore the radiosensitivity of SHG44 cells increased by suppressing the protein kinase B (PKB), in order to prove whether the PKB activity is related to the radioresistance of SHG44 cells. Methods: PKB gene(pCMV5.HA-m/p-PKBα(PKB), pCMV5.HA-PKBα-DD (T308D/S473D) (PKBD)) were transfected into SHG44 cells by electroporation, the cell proliferation rate was observed among the control, PKB transfected and irradiated groups by MTT assay. The laser confocal microscope was used to detect the changes of cell apoptosis and its microstructure in control, control + radiation, PKB transfected + radiation, PKBD transfected + radiation group. The proliferation of PKB transfected SHG44 cells and the relative factors of inducing apoptosis were analyzed. Results: The plasmid containing extrinsic PKB was successfully transfected into SHG44 cells and expressed PKB mRNA, while there was no expression in the control group; the proliferation rate of transfected SHG44 cells was significantly different from the control group (P<0.05). ⁶⁰Co γ rays could induce SHG44 cell apoptosis with the changes of cell nuclei shape. The SHG44 cells transfected by PKB in the PKB + control group were complete, with few apoptosis cells seen, while the apoptosis was more significant in PKBD + irradiation group comparing to the control-irradiation group. Conclusions: SHG44 cells transfected by PKB could resist the cell apoptosis induced by radiation, suggesting that there were some relations between PKB activity and SHG44 cells radioresistance. (authors)

[en] In this paper, a radiation-hardened resistive random-access memory (RRAM)-based non-volatile (NV) latch with a dual-interlocked storage cell is proposed and analyzed. The single-event effects of the proposed NV latch are simulated and discussed. Simulations of the proposed element are based on a 0.18 μm complementary metal-oxide-semiconductor design kit for the peripheral circuit and the voltage threshold adaptive memristor model for the RRAM. The simulation results indicate that the injected charge to induce a single-event upset (SEU) of the proposed NV latch is above 4.5 pC. As compared to the traditional RRAM based NV latch, the proposed NV latch is relatively immune to an SEU. This immunity from the SEU originates from the redundant storage nodes and interlocked feedback mechanism. Moreover, the area overhead of the proposed NV latch (eight transistors in the core storage element) are much lower than other radiation-hardened technology, e.g. TMR or FERST. (paper)

[en] To study radiosensitizing effect and apoptosis induction of wortmannin on human glioma cells, colony formation assay, flow cytometry, laser confocal microscope were used to investigate the inhibition effect on colony formation, apoptosis and cell cycle procession. Experiment results suggested that wortmannin could inhibit colony formation in SHG-44 cells, and the combination of wortmannin with ⁶⁰Co γ-irradiation showed a synergistic action. Wortmannin could also induce G₁ arrest, apoptosis, and morphological changes such as karyopyknosis, nuclear-fragmentation and apoptotic body were observed. The above results revealed that wortmannin can sensitize SHG-44 cells to gamma radiation, which might be related with G₁ arrest and apoptosis pathway. (authors)

[en] This study aimed to improve the ability to detect the effects of radiation-associated genetic damage and establish a rapid and simple method for estimating biological dose. Radiation-sensitive genes were selected as biodosimeters from Pig-a, Gadd45α, and Hprt, based on their mRNA expression level changes. RT-qPCR was used to assay the relative expression level of the target genes in peripheral blood samples of healthy non-radiation (controlgroup) and radiation workers (exposed group) and their relative expression level average, fluctuation range and variation coefficient of the background expression were counted. Peripheral blood samples of healthy adults were irradiated with different X-ray doses of 0 Gy, 0.10 Gy, 0.25 Gy, 0.50 Gy, 1.00 Gy, 2.00 Gy, and 5.00 Gy, respectively. 6 h later, the relative expression of the target genes was examined using RT-qPCR and the binomial regression curve analysis was performed to analyze the quantitative effect relationship. The results showed that Piga and Gadd45α expressions had small background level differences in the control group; Hprt had large background level differences and its variation coefficients were greater than 20%. The Hprt expression level in the control group was higher than that in the exposed group; Gadd45α and Pig-a expressions in the control group were lower than that in the exposed group (p < 0.05). There was a dose-effect relationship between the Gadd45α and Pig-a expression levels and irradiation doses, indicating that the Pig-a and Gadd45α expression level changes could be used as potential biodosimeters. (authors)

[en] In this paper, effect of fast-neutron and X-rays on the expression of P53 and CyclinB1 in small intestinal tissues of mice were investigated. The mice were randomly grouped and sacrificed 6 h after irradiation. Western blot assay was applied to detect the p53 and CyclinB 1 expressions, and flow cytometry was used to monitor changes in the small intestinal cell cycle. The results showed that the expression levels of p53 increased with irradiation dose. The expression levels of CyclinB 1 increased with the dose at first, but decreased when the dose exceeded 0.28 Gy. The results from the flow cytometry showed that the amount of cells in G2/M phase increased with the dose in both occasions. It was concluded that the low doses of fast-neutron and X-rays can make the expression levels of p53 and CyclinB 1 increase, but the expression levels of CyclinB 1 decreased and the G2 arrest occurred with increased doses. (authors)

[en] Highlights: • Self-contraction of silk fibroin induces localized densification of carbon nanotubes. • Carbon nanotubes can be densified at and below the micrometer scale. • The tensile strength of CNT fibers and narrow ribbons are increased remarkably. High densification of carbon nanotubes (CNTs) is important for high utilization efficiency of their superior properties in macroscopic assemblies. However, the conventional “top-down” compressing strategies have met problems to modify CNT assemblies at and below the micrometer scale. Here we report a molecular way to strap CNTs together via the self-contraction of silk fibroin (SF) during its drying process, resulting in a localized densification below the micrometer scale. Importantly, after the thermal removal of SF molecules, the densified assembly was well maintained. The SF-induced densification increased the average strength from 355 MPa to 960 MPa for CNT fibers, and from 1.45 GPa to 1.82 GPa for CNT ribbons, which contain much more CNTs on the surface.

[en] Highlights: • A new method based on external cost is developed to optimize gas distribution. • Impacts of gas distribution on external cost and CO₂ emission are studied. • Sensitivity analysis is been done to study the key parameters in the model. • China is selected as case study, results provide insights to other studies about energy systems. - Abstract: Natural gas, as a cleaner fossil fuel energy resource, is playing an increasingly important role in the future energy mix to achieve emission reduction target globally. In this study, a new method based on the external cost is developed to identify an optimal solution for natural gas distribution. China is selected for a case study. Both the economic cost and the external cost of pollutant emissions have been considered. The provincial distribution of natural gas and other energy resources is optimized with the aim to minimize both economic and external costs. Results show that the supply of natural gas should be prioritized for Beijing, Tianjin and Shanghai, owing to higher external costs and the optimized distribution can reduce the overall external cost by 4% in China. The optimization of natural gas distribution will also influence CO₂ emissions, therefore, the determination of the reduction target for each province should consider the external cost. Sensitivity study also shows that the minimum energy demand, the maximum natural gas supply and the minimum natural gas demand are the key parameters that impact the optimized distribution for each province.