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Now showing items 17 - 32 of 64

  • Na(+)/K(+)-ATPase inhibition upregulates NMDA-evoked currents in rat hippocampal CA1 pyramidal neurons.

    Zhang, Linan   Guo, Fang   Su, Suwen   Guo, Huicai   Xiong, Chen   Yin, Jian   Li, Wenya   Wang, Yongli  

    Na(+)/K(+)-ATPase and N-methyl-D-aspartate (NMDA) receptor in hippocampus play very important roles in the regulation of learning and memory. Here, we showed that dihydroouabain (DHO, 10(-5)-10(-3) M), a Na(+)/K(+)-ATPase inhibitor, significantly potentiated NMDA current in rat hippocampal CA1 pyramidal neurons, which was blocked by PP2 (the selective Src tyrosine kinase inhibitor) and PD-98059 [the selective inhibitor of the mitogen-activated protein kinases (MAPK) cascade]. These findings reported here uncover that Src mediates the cross-talk between Na(+)/K(+)-ATPase and NMDA receptor to transduce the signals from Na(+)/K(+)-ATPase to the MAPK cascade and provide new insights into therapeutic target for deeper understanding of the nature of cognitive disorder. =C2=A9 2011 The Authors Fundamental and Clinical Pharmacology =C2=A9 2011 Societe Francaise de Pharmacologie et de Therapeutique.
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  • A Novel Fabricating Process of Catalytic Gas Sensor Based on Droplet Generating Technology

    Wu, Liqun   Zhang, Ting   Wang, Hongcheng   Tang, Chengxin   Zhang, Linan  

    Catalytic gas sensors are widely used for measuring concentrations of combustible gases to prevent explosive accidents in industrial and domestic environments. The typical structure of the sensitive element of the sensor consists of carrier and catalyst materials, which are in and around a platinum coil. However, the size of the platinum coil is micron-grade and typically has a cylindrical shape. It is extremely difficult to control the amount of carrier and catalyst materials and to fulfill the inner cavity of the coil, which adds to the irreproducibility and uncertainty of the sensor performance. To solve this problem, this paper presents a new method which uses a drop-on-demand droplet generator to add the carrier and catalytic materials into the platinum coil and fabricate the micropellistor. The materials in this article include finely dispersed Al2O3 suspension and platinum palladium (Pd-Pt) catalyst. The size of the micropellistor with carrier material can be controlled by the number of the suspension droplets, while the amount of Pd-Pt catalyst can be controlled by the number of catalyst droplets. A bridge circuit is used to obtain the output signal of the gas sensors. The original signals of the micropellistor at 140 mV and 80 mV remain after aging treatment. The sensitivity and power consumption of the pellistor are 32 mV/% CH4 and 120 mW, respectively.
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  • Iron isotopic analyses of geological reference materials on MC-ICP-MS with instrumental mass bias corrected by three independent methods

    Zhu, Chuanwei   Lu, Wenning   He, Yongsheng   Ke, Shan   Wu, Hongjie   Zhang, Linan  

    Here we report iron (Fe) isotopic data of three pure Fe solution standards (IRMM-014, GSB Fe, and NIST 3126a) and five widely used geological reference materials (RMs) from the United States Geological Survey and Geological Survey of Japan obtained on a Neptune Plus multi-collector-inductively coupled plasma-mass spectrometer (MC-ICP-MS) in our laboratory over the past 3years. The instrumental mass bias was corrected by three independent methods: sample-standard bracketing (SSB), Ni doping+SSB, and Fe-57-Fe-58 double spike+SSB. Measurements reveal that both the Ni doping and double spike methods helped calibrate short-term fluctuations in mass bias. Collectively, almost all measurements of RMs yielded Fe-56 within +/- 0.05 of recommended values, provided that each sample was measured four times on MC-ICP-MS. For the first time, new recommended values for NIST SRM3126a are reported (Fe-56=3D0.363 +/- 0.006, 2SE, 95% CI; and Fe-57=3D0.534 +/- 0.010, 2SE).
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  • Carbon influence on hydrogen absorption and adsorption on Fe-C alloy surfaces

    Tao, Xuan   Zhang, Linan   Ma, Hongxin   Xiong, Xilin   Su, Yanjing  

    Electrochemical experiments and first-principle calculations were conducted in this study to investigate the impact of carbon doping on the adsorption and absorption on Fe-C alloy surfaces. The generalized Iyer-Pickering-Zawenzaden model was adopted to determine the kinetics related to hydrogen adsorption/absorption. Discharge rate constant k(1) was found increased with the presence of carbon, suggesting the promotion of the H2O ionization process and more hydrogen atoms were generated on the surface. Meanwhile, the recombination rate constant k(2) decreased on carbon doping surface, indicating recombination process of hydrogen atoms were inhibited. Results also showed the hydrogen surface coverage dropped with increasing carbon content. Additionally, EIS results indicate that the distance between the adsorbed hydrogen atoms and the sample surfaces is reduced by carbon doping. All experimental results are in accordance with the first-principle calculation results which demonstrate that the presence of carbon elevated the binding energy for hydrogen adsorption while lowering the energy barrier for diffusion. Thus, carbon solutes reduce the stability for hydrogen atoms to adsorb on the surface and facilitate their diffusion into the bulk.
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  • The role of non-receptor protein tyrosine kinases in the excitotoxicity induced by the overactivation of NMDA receptors

    Sun, Yongjun   Chen, You   Zhan, Liying   Zhang, Linan   Hu, Jie   Gao, Zibin  

    Protein tyrosine phosphorylation is one of the primary modes of regulation of N-methyl-d-aspartate (NMDA) receptors. The non-receptor tyrosine kinases are one of the two types of protein tyrosine kinases that are involved in this process. The overactivation of NMDA receptors is a primary reason for neuron death following cerebral ischemia. Many studies have illustrated the important role of non-receptor tyrosine kinases in ischemia insults. This review introduces the roles of Src, Fyn, focal adhesion kinase, and proline-rich tyrosine kinase 2 in the excitotoxicity induced by the overactivation of NMDA receptors following cerebral ischemia.
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  • Therapeutic Targets for Cerebral Ischemia Based on the Signaling Pathways of the GluN2B C Terminus.

    Sun, Yongjun   Zhang, Linan   Chen, You   Zhan, Liying   Gao, Zibin  

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  • A theoretical study of the effect of a non-aqueous proton donor on electrochemical ammonia synthesis

    Zhang, Linan   Sharada, Shaama Mallikarjun   Singh, Aayush R.   Rohr, Brian A.   Su, Yanjing   Qiao, Lijie   Norskov, Jens K.  

    Ammonia synthesis is one of the most studied reactions in heterogeneous catalysis. To date, however, electrochemical N-2 reduction in aqueous systems has proven to be extremely difficult, mainly due to the competing hydrogen evolution reaction (HER). Recently, it has been shown that transition metal complexes based on molybdenum can reduce N2 to ammonia at room temperature and ambient pressure in a non-aqueous system, with a relatively small amount of hydrogen output. We demonstrate that the non-aqueous proton donor they have chosen, 2,6-lutidinium (LutH(+)), is a viable substitute for hydronium in the electrochemical process at a solid surface, since this donor can suppress the HER rate. We also show that the presence of LutH(+) can selectively stabilize the *NNH intermediate relative to *NH or *NH2 via the formation of hydrogen bonds, indicating that the use of non-aqueous solvents can break the scaling relationship between limiting potential and binding energies.
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  • ON THE CONVERGENCE OF THE SINDy ALGORITHM

    Zhang, Linan   Schaeffer, Hayden  

    One way to understand time-series data is to identify the underlying dynamical system which generates it. This task can be done by selecting an appropriate model and a set of parameters which best fits the dynamics while providing the simplest representation (i.e., the smallest amount of terms). One such approach is the sparse identification of nonlinear dynamics framework [6], which uses a sparsity-promoting algorithm that iterates between a partial least-squares fit and a thresholding (sparsity-promoting) step. In this work, we provide some theoretical results on the behavior and convergence of the algorithm proposed in [S. L. Brunton, J. L. Proctor, and J. N. Kutz, Proc. Nat. Acad. Sci. USA, 113 (2016), pp. 3932-3937]. In particular, we prove that the algorithm approximates local minimizers of an unconstrained l(0)-penalized least-squares problem. From this, we provide sufficient conditions for general convergence, rate of convergence, conditions for one-step recovery, and a recovery result with respect to the condition number and noise. Examples illustrate that the rates of convergence are sharp. In addition, our results extend to other algorithms related to the algorithm in [S. L. Brunton, J. L. Proctor, and J. N. Kutz, Proc. Nat. Acad. Sci. USA, 113 (2016), pp. 3932-3937], and provide theoretical verification of several observed phenomena.
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  • Rapid cultivation and stability of autotrophic nitrifying granular sludge.

    Zhang, Linan   Long, Bei   Cheng, Yuanyuan   Wu, Junfeng   Zhang, Binchao   Zeng, Yu   Huang, Sinong   Zeng, Mingjing  

    Autotrophic nitrifying granular sludge (ANGS) was cultivated by gradually decreasing the influent organics and adding exogenous nitrifying bacteria. Under the strategy, ANGS was domesticated within 36 days. Stability of the seed heterotrophic granules decreased significantly during conversion of organic wastewater to inorganic ammonia wastewater. Obvious granular breakage was observed during these days. However, the granular debris still had good settlement performance. With microbes gradually acclimated to the new environment, the debris provided a large number of carriers for the attached growth of the exogenous nitrifying bacteria, and they replaced the heterotrophic bacteria and became the dominant species. The domesticated ANGS showed good nitrification performance during the 37th to the 183rd day (ammonia nitrogen load between 0.28 and 0.29 kg/m3 =C2=B7 d). The removal rate of ammonia nitrogen was usually more than 95%, and nitrite accumulation rate was always larger than 50%. However, nitrification ability was gradually lost with the increase of the ammonia nitrogen load (0.3-0.64 kg/m3 =C2=B7 d) from the 184th day, and it almost approached the influent ammonia nitrogen at the 269th day. Interestingly, good structure stability of the ANGS was maintained during long-term operation, and the ANGS became smoother and denser at the end of the experiment.=20
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  • Computational analysis of matrix-degrading enzymes in cancer-cell invasion

    Zhang, Linan   Kim, Dongchoul  

    Invasion is one of the hallmarks of cancer cells. Cancer cells secrete enzymes and invade the surrounding matrix. In this paper, a. new model primary study on the invasive process of cancer cells is presented. Our three-dimensional haptotaxis model consists of a,cancer-cell population, matrix-degrading enzymes (MDEs), and the extracellular matrix (ECM), and it describes two procedures for invasion by cancer cells. In the first step, cancer cells secrete MDEs, and in the next step, the secreted MDEs degrade the ECM. The simulation results thoroughly reveal that the degradation of the ECM is an influential process in cancer-cell invasion.
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  • Mesenchymal stem cells: a potential targeted-delivery vehicle for anti-cancer drug, loaded nanoparticles.

    Gao, Zibin   Zhang, Linan   Hu, Jie   Sun, Yongjun  

    UNLABELLED: The targeted delivery of anticancer agents is a promising field in anticancer therapy. Mesenchymal stem cells (MSCs) have inherent tumor-tropic and migratory properties, which allow them to serve as vehicles for targeted drug delivery systems for isolated tumors and metastatic diseases. MSCs have been successfully studied and discussed as a vehicle for cancer gene therapy. However, MSCs have not yet been discussed adequately as a potential vehicle for traditional anticancer drugs. In this review, we will examine the potential of MSCs as a targeted-delivery vehicle for anticancer drug-loaded nanoparticles (NPs), summarize various challenges, and discuss possible solutions for these challenges.; FROM THE CLINICAL EDITOR: In this review, the feasibility of mesenchymal stem cell-based targeted delivery of anticancer agents is discussed. Copyright 2013 Elsevier Inc. All rights reserved.
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  • Effect of inflammatory factor-induced cyclo-oxygenase expression on the development of reperfusion-related no-reflow phenomenon in acute myocardial infarction.

    Jiao, Qibin   Ke, Qiang   Li, Weiwei   Jin, Meihua   Luo, Yan   Zhang, Linan   Yang, Dong   Zhang, Xingwei  

    No reflow after reperfusion therapy for myocardial infarction is a strong predictor of clinical outcome. Increased levels of inflammatory factors, including C-reactive protein (CRP), in patients with acute myocardial infarction (AMI) undergoing primary percutaneous coronary intervention (PCI) may affect myocardial perfusion. However, why the no-reflow phenomenon increases in inflammation stress after PCI is not clear. The aim of the present study was to determine the effects and molecular mechanisms underlying the effects of CRP on the expression of cyclo-oxygenase (COX) on the development of the no-reflow phenomenon. There was a significant increase in plasma levels of CRP and interleukin (IL)-6 in no-reflow patients, suggesting that inflammatory factors play an important role in the development of the no-reflow phenomenon. The mechanisms involved were further evaluated after reperfusion in a rat model mimicking the no-reflow phenomenon. Compared with normal reflow rats, there were significant increases in both COX-1 and COX-2 in cardiac tissue from no-reflow rats. The COX inhibitor indomethacin (5 mg/kg, i.p.) significantly reduced the no-reflow area. In another series of experiments, human coronary artery endothelial cells (HCAEC) were treated with CRP at clinically relevant concentrations (5-25 mug/mL). C-Reactive protein significantly increased COX-1 and COX-2 levels in a time- and concentration-dependent manner. In addition, extracellular signal-regulated kinase (ERK) and Jun N-terminal kinase (JNK) were activated in CRP (5, 10, 25 mug/mL)-treated HCAEC cultures. Furthermore, the ERK inhibitor pd98059 (30 mumol/L) and the JNK inhibitor sp600125 (10 mumol/L) blocked CRP-induced COX-1 and COX-2 expression for 12 h. Together, the findings of the present study suggest that CRP can promote the development of the no-reflow phenomenon by increasing COX-1 and COX-2 expression, which is regulated, in part, via ERK and JNK activity. =C2=A9 2014 The Authors. Clinical and Experimental Pharmacology and Physiology published by Wiley Publishing Asia Pty Ltd.
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  • Isolation and expression analysis of a candidate gametophyte sex determination gene (sjhmg) of kelp (Saccharina japonica)

    Zhang, Linan   Li, Jinku   Wu, Hao   Li, Yingxia  

    Saccharina japonica undergoes an alternating life cycle during which the diploid sporophyte generation alternates with the happloid gametophyte generation. Saccharina japonica uses the UV sex determination system to determine the sex of its haploid gametophytes. However, the sex-determining genes and the sex-determining mechanisms of kelp gametophytes have not been thoroughly elucidated to date. In this study, a kelp HMG-box-containing gene (SjHMG), which is located within the sex determination region of S. japonica, was isolated and characterized. SjHMG contained an open reading frame of 1,266 bp in length and encoded a deduced protein of 421 amino acid residues with two HMG-box domains. Phylogenetic analysis showed the strongest relationship between SjHMG and its orthologs in brown algae. An alternatively spliced transcript (SjHMG isoform-2) encoding a protein of 256 amino acid residues was also identified. The two isoforms were specific for male gametophytes. A real-time quantitative PCR analysis showed significantly higher abundances of two isoforms in immature male gametophytes than in mature ones. These findings suggested that the SjHMG gene is a candidate male gametophyte determination gene of kelp. In addition, the abundance of SjHMG isoform-2 transcripts was significantly lower than that of SjHMG isoform-1 transcripts, and only an HMG-box domain was conserved among species in the order Laminariales, which indicated that the gene is specifically involved in sex regulation in some species of the order Laminariales by alternative splicing.
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  • Study of amphotericin B magnetic liposomes for brain targeting.

    Zhao, Mengyu   Hu, Jie   Zhang, Linan   Zhang, Li   Sun, Yongjun   Ma, Nan   Chen, Xiaolong   Gao, Zibin  

    This study aims to prepare amphotericin B magnetic liposomes (AmB-MLPs), which may improve drug concentration in brain, enhance magnetic targeting for brain and reduce drug toxicity in the presence of magnetic field. AmB-MLPs were prepared by means of film dispersion-ultrasonication, and their physical properties were characterized. In vivo, the magnetic targeting for brain by carotid artery administration was investigated. The particle size of AmB-MLPs was 240=C2=B111 nm, the encapsulation efficiency was 79.32=C2=B12.03%, and the saturation magnetization was 32.54 memu g=E2=81=BB at room temperature, which had good magnetic responsiveness. The group of AmB injection was delivered by carotid artery, nevertheless they all died after 20 min. AmB-MLPs were injected by carotid artery, and the drug concentration in brain tissue was obviously increased in presence of magnetic field than that of in absence of magnetic field (P<0.05). The Prussian blue staining in brain of SD rats showed that the density of blue staining-positive particles in brain tissue of applying magnetic field group was higher than that of non magnetic field group. These results suggested that AmB-MLPs could reinforce brain targeting and reduce drug toxicity when they were injected by carotid artery under the effect of magnetic field. Copyright =C2=A9 2014 Elsevier B.V. All rights reserved.
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  • Storage of aerobic granular sludge embedded in agar and its reactivation by real wastewater

    Cheng, Yuanyuan   Xuan, Xinpeng   Zhang, Linan   Zhao, Jue   Long, Bei  

    Aerobic granular sludge (AGS) was preserved using an agar embedding method to maintain its stability. No obvious damage was imposed on the granular appearance during 30 days of cold and dry storage, but the granular microstructure had an uneven surface with a large number of holes. The results were consistent with the extinction of microbial communities and the monitored consumption of extracellular polymeric substances, in which granular specific oxygen utilization rate and mixed liquor volatile suspended solids/mixed liquor suspended solids ratio, respectively, decreased by 72.4% and 62.5% during storage. A mass conversation calculation indicated that the loss of granular mass was 1.6393 g. An offensive odour was smelled during storage, and the results indicated that a material transformation and mitigation were involved between AGS and the gas phase. Although the granular structure was destroyed to a certain extent, no obvious damage was imposed on the granular skeleton during storage. After it was aerated again after a feeding with real wastewater, the residual skeleton served as a carrier for the rapid proliferation of microorganisms, and good granular properties were obtained after 11 days of reactivation.
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  • Effects of low-intensity ultrasound on nitrite accumulation and microbial characteristics during partial nitrification

    Huang, Shuchang   Zhu, Yichun   Zhang, Guangming   Lian, Junfeng   Liu, Zuwen   Zhang, Linan   Tian, Shuai  

    Ultrasound technology has attracted increasing attention in the field of sewage sludge treatment This study investigated the nitrite accumulation ratio (NAR) and microbial characteristics of the partial nitrification (PN) process in a sequencing batch reactor employing ultrasonic treatment (ultrasound density - 025 W/mL, irradiation time - 10 min). PN was achieved over 73 days with a NAR above 85% under ambient temperatures. A low dissolved oxygen (DO) environment was generated in the reactor by enhancing the oxygen utilization rate of ammonia-oxidizing bacteria (AOB). Additionally, the application of long-term ultrasonic treatment led to the enhancement of the dominance of the Nitrosomonas genus of AOB, while populations of the Nitrospira genus of nitrite-oxidizing bacteria (NOB) were eradicated. At the same time, the activities of the aerobic denitrifying bacteria Thauera, Terrimonas, Defluviimonas, and Thermomonas were enhanced and their relative abundance was increased. Overall, the results suggest that ultrasonic treatment can enhance AOB activity and generate a low DO environment that facilitates effective PN. (C) 2019 Elsevier B.V. All rights reserved.
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