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Search Results: 1 - 10 of 433134 matches for " K. S. Clifford Chao "
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Small-Molecule Synthetic Compound Norcantharidin Reverses Multi-Drug Resistance by Regulating Sonic Hedgehog Signaling in Human Breast Cancer Cells
Yu-Jen Chen, Cheng-Deng Kuo, Szu-Han Chen, Wei-Jen Chen, Wen-Chien Huang, K. S. Clifford Chao, Hui-Fen Liao
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0037006
Abstract: Multi-drug resistance (MDR), an unfavorable factor compromising treatment efficacy of anticancer drugs, involves upregulated ATP binding cassette (ABC) transporters and activated Sonic hedgehog (Shh) signaling. By preparing human breast cancer MCF-7 cells resistant to doxorubicin (DOX), we examined the effect and mechanism of norcantharidin (NCTD), a small-molecule synthetic compound, on reversing multidrug resistance. The DOX-prepared MCF-7R cells also possessed resistance to vinorelbine, characteristic of MDR. At suboptimal concentration, NCTD significantly inhibited the viability of DOX-sensitive (MCF-7S) and DOX-resistant (MCF-7R) cells and reversed the resistance to DOX and vinorelbine. NCTD increased the intracellular accumulation of DOX in MCF-7R cells and suppressed the upregulated the mdr-1 mRNA, P-gp and BCRP protein expression, but not the MRP-1. The role of P-gp was strengthened by partial reversal of the DOX and vinorelbine resistance by cyclosporine A. NCTD treatment suppressed the upregulation of Shh expression and nuclear translocation of Gli-1, a hallmark of Shh signaling activation in the resistant clone. Furthermore, the Shh ligand upregulated the expression of P-gp and attenuated the growth inhibitory effect of NCTD. The knockdown of mdr-1 mRNA had not altered the expression of Shh and Smoothened in both MCF-7S and MCF-7R cells. This indicates that the role of Shh signaling in MDR might be upstream to mdr-1/P-gp, and similar effect was shown in breast cancer MDA-MB-231 and BT-474 cells. This study demonstrated that NCTD may overcome multidrug resistance through inhibiting Shh signaling and expression of its downstream mdr-1/P-gp expression in human breast cancer cells.
The Type III Secreted Effector DspE Is Required Early in Solanum tuberosum Leaf Infection by Pectobacterium carotovorum to Cause Cell Death, and Requires Wx(3–6)D/E Motifs
Clifford S. Hogan, Beth M. Mole, Sarah R. Grant, David K. Willis, Amy O. Charkowski
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0065534
Abstract: Pectobacterium species are enterobacterial plant-pathogens that cause soft rot disease in diverse plant species. Unlike hemi-biotrophic plant pathogenic bacteria, the type III secretion system (T3SS) of Pectobacterium carotovorum subsp. carotovorum (P. carotovorum) appears to secrete only one effector protein, DspE. Previously, we found that the T3SS regulator HrpL and the effector DspE are required for P. carotovorum pathogenesis on leaves. Here, we identified genes up-regulated by HrpL, visualized expression of dspE in leaves, and established that DspE causes host cell death. DspE required its full length and WxxxE-like motifs, which are characteristic of the AvrE-family effectors, for host cell death. We also examined expression in plant leaves and showed that hrpL is required for the expression of dspE and hrpN, and that the loss of a functional T3SS had unexpected effects on expression of other genes during leaf infection. These data support a model where P. carotovorum uses the T3SS early in leaf infection to initiate pathogenesis through elicitation of DspE-mediated host cell death.
Gradient Temperature Raman Spectroscopy of Fatty Acids with One to Six Double Bonds Identifies Specific Carbons and Provides Systematic Three Dimensional Structures  [PDF]
C. Leigh Broadhurst, Walter F. Schmidt, Julie K. Nguyen, Jianwei Qin, Kuanglin Chao, Moon S. Kim
Journal of Biophysical Chemistry (JBPC) , 2018, DOI: 10.4236/jbpc.2018.91001
Abstract: Specialized pro-resolving mediators provide promising targets for new drugs and natural products. Much work has been accomplished on the structure/ function of the lipoxygenase and cyclooxygenase enzymes but not on the substrates. A better visualization of three-dimensional lipid structures will allow increased refinement of the interactions that produce the pro-resolving mediators, and lead to improvements in synthetic pathways. We present systematic analysis of oleic (18:1n-9), linoleic (18:2n-6), alpha-linolenic (18:3n-3), arachidonic (20:4n-6), docosapentaenoic (22:5n-3), and docosahexaenoic (22:6n-3) acids. Continuous gradient temperature Raman spectroscopy (GTRS) applies the temperature gradients utilized in differential scanning calorimetry to Raman spectroscopy. GTRS can identify and differentiate specific carbon chain sites, finally allowing Raman analysis to explain why the long-chain polyunsaturated fatty acids (LC-PUFA) exhibit such extreme functional differences despite minimal changes in chemical structure. Detailed vibrational analysis of the important frequency ranges 1450 - 1200 cm-1 (includes CH2 bending and twisting) and 1750 - 1425 cm-1 (includes C=C stretching and C-C stretching plus H-C in-plane rocking) shows for the first time that each molecule has its own characteristic set of modes with only some redundancy/commonality. The number and frequency of modes correlates with three-dimensional molecular structure, not the degree of unsaturation. The high degree of specificity of lipoxygenase and cyclooxygenase enzymes should be reconsidered in light of the fact that individual sites on the polyunsaturated fatty acid chain are nonequivalent, and each LC-PUFA molecule has an individual, specific
Research in Music Teaching and Learning
Madsen, Clifford K.
Revista de la Lista Electrónica Europea de Música en la Educación , 2000,
Preparation of two-particle total hyperfine spin singlet states via spin-changing dynamics
Chao-Chun Huang,M. -S. Chang,S. -K. Yip
Physics , 2012, DOI: 10.1103/PhysRevA.86.013403
Abstract: We present our proposals for generating total hyperfine spin zero state for two f=1 or two f=2 particles, starting from initial unentangled states. We show that our goal can be achieved by exploiting spin changing dynamics and quadratic Zeeman shifts with realistic choices of external magnetic fields and evolution time intervals.
Livelihood Economic Activities Causing Deforestation in Northern Ghana: Evidence of Sissala West District  [PDF]
Clifford James Fagariba, Shaoxian Song, Serge K. G. Soule
Open Journal of Ecology (OJE) , 2018, DOI: 10.4236/oje.2018.81005
Abstract: Policymakers and international organizations are making the conscious effort to address climate change through afforestation and sustainable ecosystem management. Economic activities including agriculture, mining, and infra-structure improvement to meet basic human needs continuously degrade the natural and forest resources. The rate of deforestation in Ghana is alarming due to over-reliance on forest resources by forest-dependent communities. Perceived causes of deforestation differ from individuals and groups perspec-tive. This depends on factors including environmental knowledge, education level, market demand and socio-economic activities. Simple random sampling and key informant interview with the aid of semi-structured questionnaire was used to elicit information from the indigenes of Sissala West District to determine their perceptions of causes of deforestation. The study indicated that poverty, high illiteracy, population growth and lack of alternative source of livelihood were the indirect causes which trigger livelihood economic activities such as farming, charcoal burning, wood logging and hunting leading to degradation of the ecosystem. It was also realized that majority of the indigenes are uneducated and this contributes to their unawareness of rate of de-forestation. Recommendations suggested to address challenges were enforce-ment of bye-laws and stringent government environmental policies to deter people from degrading the forest. Education, agroforestry, afforestation, and provision of alternative livelihood were also good interventions suggested.
Cervical Ectopic Pregnancy
Jag S. Heer,Denver K. Chao,Rick A. McPheeters
Western Journal of Emergency Medicine : Integrating Emergency Care with Population Health , 2012,
Abstract: [West J Emerg Med. 2012;13(1):125–126.]
Generation of spin current and polarization under dynamic gate control of spin-orbit interaction in low-dimensional semiconductor systems
C. S. Tang,A. G. Mal'shukov,K. A. Chao
Physics , 2004, DOI: 10.1103/PhysRevB.71.195314
Abstract: Based on the Keldysh formalism, the Boltzmann kinetic equation and the drift diffusion equation have been derived for studying spin polarization flow and spin accumulation under effect of the time dependent Rashba spin-orbit interaction in a semiconductor quantum well. The time dependent Rashba interaction is provided by time dependent electric gates of appropriate shapes. Several examples of spin manipulation by gates have been considered. Mechanisms and conditions for obtaining the stationary spin density and the induced rectified DC spin current are studied.
Bounding the mass of the graviton with gravitational waves: Effect of higher harmonics in gravitational waveform templates
K G Arun,Clifford M Will
Physics , 2009, DOI: 10.1088/0264-9381/26/15/155002
Abstract: Observations by laser interferometric detectors of gravitational waves from inspiraling compact binary systems can be used to search for a dependence of the waves' propagation speed on wavelength, and thereby to bound the mass or Compton wavelength of a putative graviton. We study the effect of including higher harmonics, as well as their post-Newtonian amplitude corrections, in the template gravitational waveforms employed in the process of parameter estimation using matched filtering. We consider the bounds that could be achieved using advanced LIGO, a proposed third generation instrument called Einstein Telescope, and the proposed space interferometer LISA. We find that in all cases, the bounds on the graviton Compton wavelength are improved by almost an order of magnitude for higher masses when amplitude corrections are included.
The Confrontation between General Relativity and Experiment
Will Clifford
Living Reviews in Relativity , 2001,
Abstract: The status of experimental tests of general relativity and of theoretical frameworks for analysing them are reviewed. Einstein's equivalence principle (EEP) is well supported by experiments such as the E tv s experiment, tests of special relativity, and the gravitational redshift experiment. Future tests of EEP and of the inverse square law will search for new interactions arising from unification or quantum gravity. Tests of general relativity at the post-Newtonian level have reached high precision, including the light deflection, the Shapiro time delay, the perihelion advance of Mercury, and the Nordtvedt effect in lunar motion. Gravitational wave damping has been detected in an amount that agrees with general relativity to half a percent using the Hulse-Taylor binary pulsar, and new binary pulsar systems may yield further improvements.When direct observation of gravitational radiation from astrophysical sources begins, new tests of general relativity will be possible.
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