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Search Results: 1 - 10 of 12506 matches for " Changhai Tian "
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Mitochondrial Fragmentation Is Involved in Methamphetamine-Induced Cell Death in Rat Hippocampal Neural Progenitor Cells
Changhai Tian, L. Charles Murrin, Jialin C. Zheng
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0005546
Abstract: Methamphetamine (METH) induces neurodegeneration through damage and apoptosis of dopaminergic nerve terminals and striatal cells, presumably via cross-talk between the endoplasmic reticulum and mitochondria-dependent death cascades. However, the effects of METH on neural progenitor cells (NPC), an important reservoir for replacing neurons and glia during development and injury, remain elusive. Using a rat hippocampal NPC (rhNPC) culture, we characterized the METH-induced mitochondrial fragmentation, apoptosis, and its related signaling mechanism through immunocytochemistry, flow cytometry, and Western blotting. We observed that METH induced rhNPC mitochondrial fragmentation, apoptosis, and inhibited cell proliferation. The mitochondrial fission protein dynamin-related protein 1 (Drp1) and reactive oxygen species (ROS), but not calcium (Ca2+) influx, were involved in the regulation of METH-induced mitochondrial fragmentation. Furthermore, our results indicated that dysregulation of ROS contributed to the oligomerization and translocation of Drp1, resulting in mitochondrial fragmentation in rhNPC. Taken together, our data demonstrate that METH-mediated ROS generation results in the dysregulation of Drp1, which leads to mitochondrial fragmentation and subsequent apoptosis in rhNPC. This provides a potential mechanism for METH-related neurodegenerative disorders, and also provides insight into therapeutic strategies for the neurodegenerative effects of METH.
Interferon-α Regulates Glutaminase 1 Promoter through STAT1 Phosphorylation: Relevance to HIV-1 Associated Neurocognitive Disorders
Lixia Zhao, Yunlong Huang, Changhai Tian, Lynn Taylor, Norman Curthoys, Yi Wang, Hamilton Vernon, Jialin Zheng
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0032995
Abstract: HIV-1 associated neurocognitive disorders (HAND) develop during progressive HIV-1 infection and affect up to 50% of infected individuals. Activated microglia and macrophages are critical cell populations that are involved in the pathogenesis of HAND, which is specifically related to the production and release of various soluble neurotoxic factors including glutamate. In the central nervous system (CNS), glutamate is typically derived from glutamine by mitochondrial enzyme glutaminase. Our previous study has shown that glutaminase is upregulated in HIV-1 infected monocyte-derived-macrophages (MDM) and microglia. However, how HIV-1 leads to glutaminase upregulation, or how glutaminase expression is regulated in general, remains unclear. In this study, using a dual-luciferase reporter assay system, we demonstrated that interferon (IFN) α specifically activated the glutaminase 1 (GLS1) promoter. Furthermore, IFN-α treatment increased signal transducer and activator of transcription 1 (STAT1) phosphorylation and glutaminase mRNA and protein levels. IFN-α stimulation of GLS1 promoter activity correlated to STAT1 phosphorylation and was reduced by fludarabine, a chemical that inhibits STAT1 phosphorylation. Interestingly, STAT1 was found to directly bind to the GLS1 promoter in MDM, an effect that was dependent on STAT1 phosphorylation and significantly enhanced by IFN-α treatment. More importantly, HIV-1 infection increased STAT1 phosphorylation and STAT1 binding to the GLS1 promoter, which was associated with increased glutamate levels. The clinical relevance of these findings was further corroborated with investigation of post-mortem brain tissues. The glutaminase C (GAC, one isoform of GLS1) mRNA levels in HIV associated-dementia (HAD) individuals correlate with STAT1 (p<0.01), IFN-α (p<0.05) and IFN-β (p<0.01). Together, these data indicate that both HIV-1 infection and IFN-α treatment increase glutaminase expression through STAT1 phosphorylation and by binding to the GLS1 promoter. Since glutaminase is a potential component of elevated glutamate production during the pathogenesis of HAND, our data will help to identify additional therapeutic targets for the treatment of HAND.
Two-Monopole Systems and the Formation of Non-Abelian Clouds
Changhai Lu
Physics , 1998, DOI: 10.1103/PhysRevD.58.125010
Abstract: We study the energy density of two distinct fundamental monopoles in SU(3) and Sp(4) theories with an arbitrary mass ratio. Several special limits of the general result are checked and verified. Based on the analytic expression of energy density the coefficient of the internal part of the moduli space metric is also computed, which gives it a nice "mechanical" interpretation. We then investigate the interaction energy density for both cases. By analyzing the contour of the zero interaction energy density we propose a detailed picture of what happens when one gets close to the massless limit. The study of the interaction energy density also sheds light on the formation of the non-Abelian cloud.
A Numerical Investigation of a Slow-Moving Convective Line in a Weakly Sheared Environment
Changhai LIU,

大气科学进展 , 2005,
Abstract: A series of three-dimensional, cloud-resolving numerical simulations are performed to examine a slowpropagating, quasi-two-dimensional convective system in a weakly sheared environment during the Tropical Rainfall Measuring Mission Large-Scale Biosphere-Atmosphere (TRMM-LBA) field campaign. The focus is on the kinematics and thermodynamics, organization mechanisms, and dynamical effects of low-level shear, ice microphysics and tropospheric humidity. The control simulation, which is initialized with the observed sounding and includes full microphysics, successfully replicates many observed features of the convective system, such as the linear structure, spatial orientation, life cycle, and sluggish translation.The system at the mature stage displays a line-normal structure similar to that associated with squalltype convective systems, but the corresponding mesoscale circulation and thermodynamic modification are much weaker. Ice-phase microphysical processes are not necessary to the formation of the convective system, but they play a non-trivial role in the late evolution stage. In contrast, the low-level shear, albeit shallow and weak, is critical to the realistic realization of the convective line. The tropospheric moisture above the planetary boundary layer has an important impact on the behavior of convective organization.In particular, a dry layer in the lower troposphere significantly suppresses convective development and inhibits the generation of organized convection even though the convective available potential energy is substantial. The free-atmosphere humidity has received little attention in previous studies of organized convection and warrants further investigation.
Are Participants in Bond Market Concerned about the Quality of Information Disclosure: Evidence from Chinese Listed Companies  [PDF]
Huan Luo, Changhai Yu, Ran Su
Modern Economy (ME) , 2014, DOI: 10.4236/me.2014.511095
Abstract: High quality of information disclosure can reduce the information asymmetry, which is very important to the effective operation of the capital market. This article studies whether participants in bond market are concerned about the quality of information disclosure based on a sample of listed companies in China’s bond market from 2007 to 2013. We find that there is no significant relationship between information disclosure quality and credit rating, indicating the credit rating agencies are not concerned about information disclosure quality. However, we find information disclosure quality can significantly reduce the bond financing cost, which indicates that bond investors are concerned about information disclosure quality.
Synthesis of Propargyl-Terminated Heterobifunctional Poly(ethylene glycol)
Changhai Lu,Wen Zhong
Polymers , 2010, DOI: 10.3390/polym2040407
Abstract: Novel propargyl-ended heterobifunctional poly(ethylene glycol) (PEG) derivatives with hydroxyl, carboxyl, mercapto or hydrazide end groups were synthesized with simplicity yet high efficiency. PEG ( M w = 3500 Da) with an α-hydroxyl group and an ω-carboxyl was used as the starting polymer. The carboxyl group of the bifunctional PEG was modified into a propargyl, then carboxyl, mercapto or hydrazide groups were introduced to the other end of the bifunctional PEG by modifying the bifunctional PEG’s hydroxyl group with succinic anhydride, cysteamide or tert-butyl carbazate, respectively. This method can be useful to the development of PEG-based bioconjugates for a variety of biomedical applications.
Tocilizumab: A Review of Its Safety and Efficacy in Rheumatoid Arthritis
Graeme Jones and Changhai Ding
Clinical Medicine Insights: Arthritis and Musculoskeletal Disorders , 2012, DOI: 10.4137/CMAMD.S4864
Abstract: Recent years have seen many exciting developments in the treatment of rheumatoid arthritis. Tocilizumab (TCZ) is a monoclonal antibody which inhibits the interleukin-6 receptor. After initial studies in Japan, it has been extensively studied in five multicentre clinical trials. This report summarises the key efficacy and toxicity findings from the major clinical trials. TCZ works quickly and effectively in rheumatoid arthritis either as monotherapy or in combination with other agents in early disease, DMARD inadequate responders, seronegative disease and after anti-TNF failure. The toxicity profile is manageable but includes infections (most notably skin and soft tissue), increases in serum cholesterol, transient decreases in neutrophil count and abnormal liver function tests (especially in combination with methotrexate). In summary, there is sufficient evidence to make TCZ a first line biologic therapy for rheumatoid arthritis especially for those who are unable to take methotrexate or who fail anti-TNF therapy.
Tocilizumab: A Review of Its Safety and Efficacy in Rheumatoid Arthritis
Graeme Jones,Changhai Ding
Clinical Medicine Insights: Arthritis and Musculoskeletal Disorders , 2010,
Two Massive and One Massless Sp(4) Monopoles
Kimyeong Lee,Changhai Lu
Physics , 1997, DOI: 10.1103/PhysRevD.57.5260
Abstract: Starting from Nahm's equations, we explore BPS magnetic monopoles in the Yang-Mills Higgs theory of gauge group $Sp(4)$ which is broken to $SU(2)\times U(1)$. A family of BPS field configurations with purely Abelian magnetic charge describe two identical massive monopoles and one massless monopole. We construct the field configurations with axial symmetry by employing the ADHMN construction, and find the explicit expression of the metrics for the 12-dimensional moduli space of Nahm data and its submanifolds.
SU(2) Calorons and Magnetic Monopoles
Kimyeong Lee,Changhai Lu
Physics , 1998, DOI: 10.1103/PhysRevD.58.025011
Abstract: We investigate the self-dual Yang-Mills gauge configurations on $R^3\times S^1$ when the gauge symmetry SU(2) is broken to U(1) by the Wilson loop. We construct the explicit field configuration for a single instanton by the Nahm method and show that an instanton is composed of two self-dual monopoles of opposite magnetic charge. We normalize the moduli space metric of an instanton and study various limits of the field configuration and its moduli space metric.
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