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  • 1
    Publication Date: 2018-10-02
    Description: Previous studies have demonstrated the feasibility of absolute quantification of dynamic 123 I-metaiodobenzylguanidine ( 123 I-MIBG) SPECT imaging in humans. This work reports a simplified quantification method for dynamic 123 I-MIBG SPECT using practical protocols with shortened acquisition time and voxel-by-voxel parametric imaging. Methods: Twelve healthy human volunteers underwent five 15-min dynamic SPECT scans at 0, 15, 90, 120, and 180 min after 123 I-MIBG injection. List-mode SPECT data were binned into 29 frames and reconstructed with corrections for attenuation, scatter, and decay. Population-based blood-to-plasma correction and metabolite correction were applied to the image-derived input function. Likelihood estimation in graphical analysis (LEGA) was used as a simplified model to obtain volume of distribution ( V T ) values, which were compared with those obtained with the reversible 2-tissue (2T) compartment model. Three simplified protocols were evaluated with 2T and LEGA using a 30-min scan started simultaneously with tracer injection plus a 15-min scan at 90, 120, or 180 min after injection. Voxel-by-voxel LEGA fitting was applied to the aligned dynamic images using both the full protocol (five 15-min scans) and the simplified protocols. Results: Correlation analysis ( y = 0.955 x + 0.547, R 2 = 0.997) and Bland–Altman plot (mean difference, –0.8 mL/cm 3 ; 95% limits of agreement, [–2.5, 1.0] mL/cm 3 ; normal V T range, 29.0 ± 12.4 mL/cm 3 ) showed that LEGA can be used as a simplified model of 2T for 123 I-MIBG. High-quality V T parametric images could be obtained with LEGA. Region-of-interest (ROI) modeling and parametric imaging results were in excellent agreement as determined by correlation analysis ( y = 0.999 x – 1.026, R 2 = 0.982) and Bland–Altman plot (mean difference, –1.0 mL/cm 3 ; 95% limits of agreement, [–4.2, 2.1] mL/cm 3 ). V T correlated reasonably well between all simplified protocols and the full protocol with LEGA but not with 2T. The V T results were more reliable when there was a longer interval between the 2 acquisitions in the simplified protocols. Conclusion: For ROI-based kinetic modeling and parametric imaging, reliable quantification of dynamic 123 I-MIBG SPECT can be achieved with LEGA using a simplified protocol of a 30-min scan starting with tracer injection plus a 15-min scan no earlier than 180 min after injection.
    Print ISSN: 0022-3123
    Topics: Medicine
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  • 2
    Publication Date: 2018-11-03
    Description: Quantum oscillations are usually the manifestation of the underlying physical nature in condensed matter systems. Here, we report a new type of log-periodic quantum oscillations in ultraquantum three-dimensional topological materials. Beyond the quantum limit (QL), we observe the log-periodic oscillations involving up to five oscillating cycles (five peaks and five dips) on the magnetoresistance of high-quality single-crystal ZrTe 5 , virtually showing the clearest feature of discrete scale invariance (DSI). Further, theoretical analyses show that the two-body quasi-bound states can be responsible for the DSI feature. Our work provides a new perspective on the ground state of topological materials beyond the QL.
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
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  • 3
    Publication Date: 2018-05-10
    Description: Agrocybe cylindracea substrate–Fe 3 O 4 (ACS–Fe 3 O 4 ), a Fe 3 O 4 nanoparticle-coated biomaterial derived from agriculture waste from mushroom cultivation, was developed to remove hexavalent chromium (Cr(VI)) from liquid. After modification, material surface became uneven with polyporous and crinkly structure which improved Cr-accommodation ability in a sound manner. Optimized by the Taguchi method, Cr(VI) removal percentage was up to 73.88 at 240 min, 40°C, pH 3, Cr(VI) concentration 200 mg l –1 , dosage 12 g l –1 , rpm 200. The efficient Cr(VI) removal was due to the combined effect of adsorption and redox. In addition, verification test using tannery wastewater, with removal percentage of Cr(VI) and total Cr reaching 98.35 and 95.6, provided further evidence for the efficiency and feasibility of ACS–Fe 3 O 4 . The effect of storage time of the material on Cr(VI) removal was small, which enhanced its value in practical application. Results indicated that metal removal was mainly influenced by solution concentration, adsorbent dosage and treatment time. The experimental data obtained were successfully fitted with the Langmuir isotherm model. Thermodynamic study indicated the endothermic nature of the process. The results confirmed that ACS–Fe 3 O 4 as novel material derived from waste, with long-term stability, could be applied for heavy metal removal from wastewater and waste cycling.
    Keywords: biomaterials, environmental science
    Electronic ISSN: 2054-5703
    Topics: Natural Sciences in General
    Published by Royal Society
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  • 4
    Publication Date: 2018-03-06
    Description: Purpose: Squamous cell carcinoma of tongue (SCCT) is the most common type of oral cavity carcinoma. Chemoresistance in SCCT is common, and the underlying mechanism remains largely unknown. We aimed to identify key molecules and signaling pathways mediating chemoresistance in SCCT. Experimental Design: Using a proteomic approach, we found that the HSP27 was a potential mediator for chemoresistance in SCCT cells. To further validate this role of HSP27, we performed various mechanistic studies using in vitro and in vivo models as well as serum and tissue samples from SCCT patients. Results: The HSP27 protein level was significantly increased in the multidrug-resistant SCCT cells and cell culture medium. Both HSP27 knockdown and anti-HSP27 antibody treatment reversed chemoresistance. Inversely, both HSP27 overexpression and recombinant human HSP27 protein treatment enhanced chemoresistance. Moreover, chemotherapy significantly induced HSP27 protein expression in both SCCT cells and their culture medium, as well as in tumor tissues and serum of SCCT patients. HSP27 overexpression predicts a poor outcome for SCCT patients receiving chemotherapy. Mechanically, extracellular HSP27 binds to TLR5 and then activates NF-B signaling to maintain SCCT cell survival. TLR5 knockdown or restored IBα protein level disrupts extracellular HSP27-induced NF-B transactivation and chemoresistance. Moreover, intracellular HSP27 binds to BAX and BIM to repress their translocation to mitochondrion and subsequent cytochrome C release upon chemotherapy, resulting in inhibition of the mitochondrial apoptotic pathway. Conclusions: HSP27 plays a pivotal role in chemoresistance of SCCT cells via a synergistic extracellular and intracellular signaling. HSP27 may represent a potential biomarker and therapeutic target for precision SCCT treatment. Clin Cancer Res; 24(5); 1163–75. ©2017 AACR .
    Print ISSN: 1078-0432
    Electronic ISSN: 1557-3265
    Topics: Medicine
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  • 5
    Publication Date: 2018-03-14
    Description: Dendritic cells (DCs) contribute to psoriasis pathogenesis. In a mouse model of imiquimod-induced psoriasiform skin inflammation, we found that p38α activity in Langerhans cells (LCs), a skin-resident subset of DCs, promoted the generation of T cells that produce IL-17, a proinflammatory cytokine that is implicated in autoimmune disease. Deletion of p38α in LCs, but not in other skin or circulating DC subsets or T cells, decreased T cell–mediated psoriasiform skin inflammation in mice. The activity of p38α in LCs specifically promoted IL-17 production from and CD4 + T cells by increasing the abundance of IL-23 and IL-6, two cytokines that stimulate IL-17 secretion. Inhibition of p38 activity through either pharmacological inhibition or genetic deletion also reduced the severity of established psoriasiform skin inflammation. Together, our findings indicate a critical role for p38α signaling in LCs in promoting inflammatory responses in the skin and suggest that targeting p38α signaling in LCs may offer an effective therapeutic approach to treat psoriasis.
    Print ISSN: 1945-0877
    Topics: Medicine
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  • 6
    Publication Date: 2018-02-21
    Description: Dysregulation of the immune barrier function of the intestinal epithelium can often result in dysbiosis. In this study we report a novel role of intestinal epithelial cell (IEC)-derived liver kinase B1 (LKB1) in suppressing colitogenic microbiota. IEC-specific deletion of LKB1 (LKB1 IEC ) resulted in an increased susceptibility to dextran sodium sulfate (DSS)-induced colitis and a definitive shift in the composition of the microbial population in the mouse intestine. Importantly, transfer of the microbiota from LKB1 IEC mice was sufficient to confer increased susceptibility to DSS-induced colitis in wild-type recipient mice. Collectively, the data indicate that LKB1 deficiency in intestinal epithelial cells nurtures the outgrowth of colitogenic bacteria in the commensal community. In addition, LKB1 deficiency in the intestinal epithelium reduced the production of IL-18 and antimicrobial peptides in the colon. Administration of exogenous IL-18 restored the expression of antimicrobial peptides, corrected the outgrowth of several bacterial genera, and rescued the LKB1 IEC mice from increased sensitivity to DSS challenge. Taken together, our study reveals an important function of LKB1 in IECs for suppressing colitogenic microbiota by IL-18 expression.
    Print ISSN: 0022-1767
    Electronic ISSN: 1550-6606
    Topics: Medicine
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  • 7
    Publication Date: 2018-02-09
    Description: Poly(ADP-ribose) polymerase (PARP) is an NAD-consuming enzyme and its specific role in the pathogenesis of alcoholic fatty liver disease (AFLD) remains elusive. In this study, we applied PJ34 [ N -(5,6-dihydro-6-oxo-2-phenanthridinyl)-2-acetamide hydrochloride] to inhibit hepatic PARP activity to examine the corresponding pathologic alteration in AFLD in mice and the underlying molecular mechanism. We found that PJ34 decreased the intracellular triglyceride (TG) content in hepatocytes. Moreover, PJ34 suppressed the gene expression of diglyceride acyltransferases DGAT1 and DGAT2 and elevated intracellular NAD + levels in hepatocytes. These mechanistic observations were validated in alcohol-fed mice injected with PJ34 intraperitoneally. Our results indicate that the PJ34 injection attenuated hepatic TG accumulation in alcohol-fed mice. Furthermore, PJ34 injection lowered the gene expression of hepatic sterol regulatory element binding protein 1c, DGAT1, and DGAT2, whereas PJ34 injection augmented hepatic NAD + levels in alcohol-fed mice. Finally, nicotinamide riboside supplementation alleviated hepatic TG accumulation in alcohol-fed mice. These data indicate that applying PARP-specific inhibitor PJ34 by intraperitoneal injection attenuated hepatic NAD + depletion and TG accumulation in alcohol-fed mice and may be a potential candidate for use in AFLD therapy.
    Print ISSN: 0022-3565
    Electronic ISSN: 1521-0103
    Topics: Medicine
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  • 8
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The temperature distribution and evolution of metal field-ion emitters under pulsed and continuous-wave (cw) laser irradiation are obtained numerically using implicit alternating direction method. For the cw laser irradiation, the temperature distribution in the emitter reaches a steady-state value after approximately 2 μs of laser heating. The peak temperature of the tip apex reached depends almost linearly on the incident energy flux of the laser beam, and also on the cone angle of the emitter. For the fast laser pulse, both the waveform and the spatial intensity variation of the laser beam are considered. The numerical result is found to differ only slightly from that obtained by assuming a square shape of the laser pulse. The feasibility and advantages of using a laser beam as a means of heating the emitter in the study of single atom surface diffusion and adatom-adatom interaction, laser-induced silicide interface formation, and other studies with the Atom Probes and Field Ion Microscope are also discussed.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1436-5065
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Summary  A three-dimensional, nonhydrostatic numerical model with high spatial resolution, in which a simple energy closure scheme is employed, has been developed to simulate the spray dispersion over complex terrain. The evaporation, condensation, and dispersion of the spray and moisture are taken into account in model equations. The term of latent heat due to phase transformation is considered in detail to account for its effects on the temperature field and airflow. As an application of the model, the spray concentration and air relative humidity are calculated under neutral condition. The results indicate that under the neutral condition, the spray is transported to about 0.6 km downwind from the source, and its effects on the air humidity reach a further distance of 0.9 km downwind from the source. Attention is given to the dependence of the results upon the various factors influencing the simulation, such as the intensity of the source, the atmospheric stratification, and the dynamic factor of the terrain. Some numerical tests were carried out to provide extra insight to the effects of these factors. It has been demonstrated that the simulation results such as relative humidity and temperature are sensitive to these factors, especially to the thermal stratification. Under unstable conditions, the effects of the spray source increase significantly, and the variation extent of the temperature, relative humidity and flow field is larger than that under neutral condition. The effects of dynamic and thermal factors on the air flow field are discussed through the comparison of the modeling results over complex terrain and flat terrain.
    Type of Medium: Electronic Resource
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  • 10
    Publication Date: 2018-05-19
    Description: Ether bond activation is very interesting because the synthesis of many valuable compounds involves conversion of ethers. Moreover, C–O bond cleavage is also very important for the transformation of biomass, especially lignin, which abundantly contains ether bonds. Developing efficient methods to activate aromatic ether bonds has attracted much attention. However, this is a challenge because of the inertness of aryl ether bonds. We proposed a new route to activate aryl methyl ether bonds and synthesize aryl acetates by carbonylation of aryl methyl ethers. The reaction could proceed over RhCl 3 in the presence of LiI and LiBF 4 , and moderate to high yields of aryl acetates could be obtained from transformation of various aryl methyl ethers with different substituents. It was found that LiBF 4 could assist LiI to cleave aryl methyl ether bonds effectively. The reaction mechanism was proposed by a combination of experimental and theoretical studies.
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
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