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Search Results: 1 - 10 of 117991 matches for " T. Huse "
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Microtubule-organizing center polarity and the immunological synapse: protein kinase C and beyond
Morgan Huse
Frontiers in Immunology , 2012, DOI: 10.3389/fimmu.2012.00235
Abstract: Cytoskeletal polarization is crucial for many aspects of immune function, ranging from neutrophil migration to the sampling of gut flora by intestinal dendritic cells. It also plays a key role during lymphocyte cell–cell interactions, the most conspicuous of which is perhaps the immunological synapse (IS) formed between a T cell and an antigen-presenting cell (APC). IS formation is associated with the reorientation of the T cell’s microtubule-organizing center (MTOC) to a position just beneath the cell–cell interface. This cytoskeletal remodeling event aligns secretory organelles inside the T cell with the IS, enabling the directional release of cytokines and cytolytic factors toward the APC. MTOC polarization is therefore crucial for maintaining the specificity of a T cell’s secretory and cytotoxic responses. It has been known for some time that T cell receptor (TCR) stimulation activates the MTOC polarization response. It has been difficult, however, to identify the machinery that couples early TCR signaling to cytoskeletal remodeling. Over the past few years, considerable progress has been made in this area. This review will present an overview of recent advances, touching on both the mechanisms that drive MTOC polarization and the effector responses that require it. Particular attention will be paid to both novel and atypical members of the protein kinase C family, which are now known to play important roles in both the establishment and the maintenance of the polarized state.
Inhibitory Receptor Signaling Destabilizes Immunological Synapse Formation in Primary NK Cells
Morgan Huse
Frontiers in Immunology , 2013, DOI: 10.3389/fimmu.2013.00410
Abstract: Upon engagement of their cognate class I major histocompatibility complex ligands, receptors containing immunotyrosine-based inhibitory motifs (ITIMs) transduce signals that block cytolytic and inflammatory responses. In this manner, ITIM-coupled receptors play a crucial role in maintaining natural killer (NK) cell tolerance toward normal, healthy tissue. A number of studies, mostly using immortalized NK cell lines, have demonstrated that ITIM signaling functions by disrupting the cytolytic immunological synapse formed between an NK cell and its target. However, more recent imaging experiments using primary NK cells have suggested that inhibitory receptor engagement does not antagonize contact formation, casting doubt on the hypothesis that ITIM signals destabilize the synapse. To resolve this issue, we analyzed primary NK cell activation and contact formation on supported lipid bilayers containing controlled combinations of activating and inhibitory ligands. Under these conditions, we observed that ITIM signaling clearly inhibited adhesion, cell arrest, and calcium influx, three hallmarks of synapse formation. These results are consistent with previous reports showing that inhibitory receptors deliver a “reverse stop” signal, and confirm that ITIM signaling functions at least in part by destabilizing cytolytic synapse formation.
Nonlocal Conductivity in Type-II Superconductors
Chung-Yu Mou,Rachel Wortis,Alan T. Dorsey,David A. Huse
Physics , 1994, DOI: 10.1103/PhysRevB.51.6575
Abstract: Multiterminal transport measurements on YBCO crystals in the vortex liquid regime have shown nonlocal conductivity on length scales up to 50 microns. Motivated by these results we explore the wavevector ({\bf k}) dependence of the dc conductivity tensor, $\sigma_{\mu\nu} ({\bf k})$, in the Meissner, vortex lattice, and disordered phases of a type-II superconductor. Our results are based on time-dependent Ginzburg-Landau (TDGL) theory and on phenomenological arguments. We find four qualitatively different types of behavior. First, in the Meissner phase, the conductivity is infinite at $k=0$ and is a continuous function of $k$, monotonically decreasing with increasing $k$. Second, in the vortex lattice phase, in the absence of pinning, the conductivity is finite (due to flux flow) at $k=0$; it is discontinuous there and remains qualitatively like the Meissner phase for $k>0$. Third, in the vortex liquid regime in a magnetic field and at low temperature, the conductivity is finite, smooth and {\it non-monotonic}, first increasing with $k$ at small $k$ and then decreasing at larger $k$. This third behavior is expected to apply at temperatures just above the melting transition of the vortex lattice, where the vortex liquid shows strong short-range order and a large viscosity. Finally, at higher temperatures in the disordered phase, the conductivity is finite, smooth and again monotonically decreasing with $k$. This last, monotonic behavi or applies in zero magnetic field for the entire disordered phase, i.e. at all temperatures above $T_c$, while in
miR-34a Repression in Proneural Malignant Gliomas Upregulates Expression of Its Target PDGFRA and Promotes Tumorigenesis
Joachim Silber, Anders Jacobsen, Tatsuya Ozawa, Girish Harinath, Alicia Pedraza, Chris Sander, Eric C. Holland, Jason T. Huse
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0033844
Abstract: Glioblastoma (GBM) and other malignant gliomas are aggressive primary neoplasms of the brain that exhibit notable refractivity to standard treatment regimens. Recent large-scale molecular profiling has revealed distinct disease subclasses within malignant gliomas whose defining genomic features highlight dysregulated molecular networks as potential targets for therapeutic development. The “proneural” designation represents the largest and most heterogeneous of these subclasses, and includes both a large fraction of GBMs along with most of their lower-grade astrocytic and oligodendroglial counterparts. The pathogenesis of proneural gliomas has been repeatedly associated with dysregulated PDGF signaling. Nevertheless, genomic amplification or activating mutations involving the PDGF receptor (PDGFRA) characterize only a subset of proneural GBMs, while the mechanisms driving dysregulated PDGF signaling and downstream oncogenic networks in remaining tumors are unclear. MicroRNAs (miRNAs) are a class of small, noncoding RNAs that regulate gene expression by binding loosely complimentary sequences in target mRNAs. The role of miRNA biology in numerous cancer variants is well established. In an analysis of miRNA involvement in the phenotypic expression and regulation of oncogenic PDGF signaling, we found that miR-34a is downregulated by PDGF pathway activation in vitro. Similarly, analysis of data from the Cancer Genome Atlas (TCGA) revealed that miR-34a expression is significantly lower in proneural gliomas compared to other tumor subtypes. Using primary GBM cells maintained under neurosphere conditions, we then demonstrated that miR-34a specifically affects growth of proneural glioma cells in vitro and in vivo. Further bioinformatic analysis identified PDGFRA as a direct target of miR-34a and this interaction was experimentally validated. Finally, we found that PDGF-driven miR-34a repression is unlikely to operate solely through a p53-dependent mechanism. Taken together, our data support the existence of reciprocal negative feedback regulation involving miR-34 and PDGFRA expression in proneural gliomas and, as such, identify a subtype specific therapeutic potential for miR-34a.
Resistance due to vortex motion in the $ν=1$ bilayer quantum Hall superfluid
David A. Huse
Physics , 2004, DOI: 10.1103/PhysRevB.72.064514
Abstract: The longitudinal and Hall resistances have recently been measured for quantum Hall bilayers at total filling $\nu=1$ in the superfluid state with interlayer pairing, both for currents flowing parallel to one another and for "counterflowing" currents in the two layers. Here I examine the contribution to these resistances from the motion of unpaired vortices in these systems, developing some possible explanations of various qualitative features of these data.
Synthesis and Characterization of Cr Doped ZnO Nanocrystals  [PDF]
Vishwanath Dattu Mote, Vishnu Ramrao Huse, Babasaheb Nivrutti Dole
World Journal of Condensed Matter Physics (WJCMP) , 2012, DOI: 10.4236/wjcmp.2012.24035
Abstract: Samples of chromium doped ZnO were synthesized using co-precipitation technique at room temperature. Structural and optical properties of Cr doped ZnO samples were investigated by X-ray diffraction technique (XRD and UV-Visible spectroscopy (UV-Vis) respectively. X-ray diffraction (XRD) patterns confirm that the samples have hexagonal (wurtzite) structure with no additional peak which suggests that Cr ions go to the regular Zn sites in the ZnO crystal structure. The lattice constants were calculated using X-ray diffraction data and it is found that lattice parameters decrease with increasing Cr content. The average grain size was calculated using Scherrer’s formula for pure and Cr doped ZnO samples and it is observed that grain size is in the range 11 to17 nm. Band gap of Zn1–xCrxO samples has been evaluated using UV-Vis spectrometer. It is found that the band gap decreases as Cr increases; it is attributed to the s-d and p interactions and the smaller average grain size. It indicates that incorporation of Cr ions into the ZnO matrix. The chemical species of the grown crystals were identified by Fourier transform infrared spectroscopy (FTIR). From FTIR spectra it is observed that IR peaks corresponding to the Zn-O bands. Such results are presented in this paper quantitatively and qualitatively.
The Crystallographic and Optical Studies on Cobalt Doped CdS Nanoparticles  [PDF]
Vishnu R. Huse, Vishwanath D. Mote, Babasaheb N. Dole
World Journal of Condensed Matter Physics (WJCMP) , 2013, DOI: 10.4236/wjcmp.2013.31008
Abstract:

The samples of Cd1 - xCoxS with compositions x = 0.0 & 0.6 were prepared by Co-precipitation route at room temperature. XRD analysis confirms that the samples have cubic structure with no impurity phases. The lattice parameter, volume cell, X-ray density and grain size were calculated using XRD data. It is found that lattice parameter, volume of unit cell and X-ray density decrease with enhancing Co content. It is due to the smaller ionic radius of Co than the Cd. It is well noticed that the grain size increases with increasing Co content, it may be owing to the good synthesis technique. The functional groups and chemical interaction were determined by FTIR spectra. From FTIR spectra, it is investigated that absorption bands show the presence of resonance interaction between vibrational modes of oxide ions in the crystal. The energy band gap of Co doped CdS samples was calculated using UV-Vis analysis. It is observed that energy band gap decreases with increasing Co content owing to the sp-d exchange interaction between Co and CdS atoms.

Recruited Cells Can Become Transformed and Overtake PDGF-Induced Murine Gliomas In Vivo during Tumor Progression
Elena I. Fomchenko,Joseph D. Dougherty,Karim Y. Helmy,Amanda M. Katz,Alexander Pietras,Cameron Brennan,Jason T. Huse,Ana Milosevic,Eric C. Holland
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0020605
Abstract: Gliomas are thought to form by clonal expansion from a single cell-of-origin, and progression-associated mutations to occur in its progeny cells. Glioma progression is associated with elevated growth factor signaling and loss of function of tumor suppressors Ink4a, Arf and Pten. Yet, gliomas are cellularly heterogeneous; they recruit and trap normal cells during infiltration.
Observation of antiferromagnetic correlations in the Hubbard model with ultracold atoms
Russell A. Hart,Pedro M. Duarte,Tsung-Lin Yang,Xinxing Liu,Thereza Paiva,Ehsan Khatami,Richard T. Scalettar,Nandini Trivedi,David A. Huse,Randall G. Hulet
Physics , 2014, DOI: 10.1038/nature14223
Abstract: Ultracold atoms in optical lattices have great potential to contribute to a better understanding of some of the most important issues in many-body physics, such as high-$T_c$ superconductivity. The Hubbard model describes many of the features shared by the copper oxides, including an interaction-driven Mott insulating state and an antiferromagnetic (AFM) state. Optical lattices filled with a two-spin-component Fermi gas of ultracold atoms can faithfully realise the Hubbard model with readily tunable parameters, and thus provide a platform for the systematic exploration of its phase diagram. Realisation of strongly correlated phases, however, has been hindered by the need to cool the atoms to temperatures as low as the magnetic exchange energy, and also by the lack of reliable thermometry. Here we demonstrate spin-sensitive Bragg scattering of light to measure AFM spin correlations in a realisation of the 3D Hubbard model at temperatures down to 1.4 times that of the AFM phase transition. This temperature regime is beyond the range of validity of a simple high-temperature series expansion, which brings our experiment close to the limit of the capabilities of current numerical techniques. We reach these low temperatures using a unique compensated optical lattice technique, in which the confinement of each lattice beam is compensated by a blue-detuned laser beam. The temperature of the atoms in the lattice is deduced by comparing the light scattering to determinantal quantum Monte Carlo and numerical linked-cluster expansion calculations. Further refinement of the compensated lattice may produce even lower temperatures which, along with light scattering thermometry, would open avenues for achieving and characterising other novel quantum states of matter, such as the pseudogap regime of the 2D Hubbard model.
The Phase Transition to a Square Vortex Lattice in Type-II Superconductors with Fourfold Anisotropy
Kyungwha Park,David A. Huse
Physics , 1998, DOI: 10.1103/PhysRevB.58.9427
Abstract: We investigate the stability of the square vortex lattice which has been recently observed in experiments on the borocarbide family of superconductors. Taking into account the tetragonal symmetry of these systems, we add fourfold symmetric fourth-derivative terms to the Ginzburg-Landau(GL) free energy. At $H_{c2}$ these terms may be treated perturbatively to lowest order to locate the transition from a distorted hexagonal to a square vortex lattice. We also solve for this phase boundary numerically in the strongly type-II limit, finding large corrections to the lowest-order perturbative results. We calculate the relative fourfold $H_{c2}$ anisotropy for field in the $xy$ plane to be 4.5% at the temperature, $T_c^{\Box}$, where the transition occurs at $H_{c2}$ for field along the $z$ axis. This is to be compared to the 3.6% obtained in the perturbative calculation. Furthermore, we find that the phase boundary in the $H-T$ phase diagram has positive slope near $H_{c2}$.
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