bluuebunny/crossref_metadata_2025 huggingface dataset:
A Host-Specific, Temperature-Sensitive Translation Defect Determines the Attenuation Phenotype of a Human Rhinovirus/Poliovirus Chimera, PV1(RIPO)
Authors: Jahan Nusrat , Wimmer Eckard , Mueller Steffen
Published: May 2011

By using a rhinosvirus/poliovirus type 1 chimera, PV1(RIPO), with the cognate internal ribosome entry site (IRES) of human rhinovirus type 2 (HRV2), we set out to shed light on the mechanism by which this variant expresses its attenuated phenotype in poliovirus-sensitive, CD155 transgenic (tg) mice and cynomolgus monkeys. Here we report that replication of PV1(RIPO) is restricted not only in human cells of neuronal origin, as was reported previously, but also in cells of murine origin at physiological temperature. This block in replication was enhanced at 39.5°C but, remarkably, it was absent at 33°C. PV1(RIPO) variants that overcame the replication block were derived by serial passage under restrictive conditions in either mouse cells or human neuronal cells. All adapting mutations mapped to the 5′-nontranslated region of PV1(RIPO). Variants selected in mouse cells, but not in human neuronal cells, exhibited increased mouse neurovirulence
in vivo
. The observed strong mouse-specific defect of PV1(RIPO) at nonpermissive temperature correlated with the translational activity of the HRV2 IRES in this chimeric virus. These unexpected results must be kept in mind when poliovirus variants are tested in CD155 tg mice for their neurovirulent potential, particularly in assays of live attenuated oral poliovirus vaccine lots. Virulence may be masked by adverse species-specific conditions in mouse cells that may not allow accurate prediction of neurovirulence in the human host. Thus, novel poliovirus variants in line for possible development of human vaccines must be tested in nonhuman primates.
The E3 Ubiquitin Ligase Activity Associated with the Adenoviral E1B-55K–E4orf6 Complex Does Not Require CRM1-Dependent Export
Authors: Schmid Melanie , Kindsmüller Kathrin , Wimmer Peter , Groitl Peter , Gonzalez Ramon A. , Dobner Thomas
Published: May 2011

The adenovirus type 5 (Ad5) E1B-55K and E4orf6 (E1B-55K/E4orf6) proteins are multifunctional regulators of Ad5 replication, participating in many processes required for virus growth. A complex containing the two proteins mediates the degradation of cellular proteins through assembly of an E3 ubiquitin ligase and induces shutoff of host cell protein synthesis through selective nucleocytoplasmic viral late mRNA export. Both proteins shuttle between the nuclear and cytoplasmic compartments via leucine-rich nuclear export signals (NES). However, the role of their NES-dependent export in viral replication has not been established. It was initially shown that mutations in the E4orf6 NES negatively affect viral late gene expression in transfection/infection complementation assays, suggesting that E1B-55K/E4orf6-dependent viral late mRNA export involves a CRM1 export pathway. However, a different conclusion was drawn from similar studies showing that E1B-55K/E4orf6 promote late gene expression without active CRM1 or functional NES. To evaluate the role of the E1B-55K/E4orf6 NES in viral replication in the context of Ad-infected cells and in the presence of functional CRM1, we generated virus mutants carrying amino acid exchanges in the NES of either or both proteins. Phenotypic analyses revealed that mutations in the NES of E1B-55K and/or E4orf6 had no or only moderate effects on viral DNA replication, viral late protein synthesis, or viral late mRNA export. Significantly, such mutations also did not interfere with the degradation of cellular substrates, indicating that the NES of E1B-55K or E4orf6 is dispensable both for late gene expression and for the activity associated with the E3 ubiquitin ligase.
X-configuration intersecting Enterprise stents for vascular remodeling and assisted coil embolization of a wide neck anterior communicating artery aneurysm
Authors: Lazzaro Marc A , Zaidat Osama O
Published: May 2011

Background

Intracranial stent technology and techniques have expanded the applications of endovascular therapy for complex intracranial aneurysms. Various methods of stent assisted coil embolization have been described. An additional technique of X-configuration intersecting Enterprise stent implantation with trans-stent microcatheterization for the treatment of a wide neck anterior communicating artery aneurysm is presented.

Results

Successful X-configuration intersecting stent implantation and coil embolization of a wide neck aneurysm is reported with no perioperative complications.

Conclusions

The technique of trans-stent microcatheterization with X-configuration intersecting Enterprise stent implantation for the treatment of wide neck anterior communicating artery aneurysms is technically feasible. Further study is needed to evaluate technical success, procedural outcome and long term angiographic results.
A NEW METHODOLOGY FOR THE CONSTRUCTION OF OPTIMIZED RUNGE–KUTTA–NYSTRÖM METHODS
Authors: PAPADOPOULOS D. F. , SIMOS T. E.
Published: May 2011

In this paper, a new Runge–Kutta–Nyström method of fourth algebraic order is developed. The new method has zero phase-lag, zero amplification error and zero first integrals of the previous properties. Numerical results indicate that the new method is very efficient for solving numerically the Schrödinger equation. We note that for the first time in the literature we use the requirement of vanishing the first integrals of phase-lag and amplification error in the construction of efficient methods for the numerical solution of the Schrödinger equation.
A COMPARATIVE STUDY OF OXYGEN LOSS ON IN SITU HEATING IN PrMnO3 AND BaMnO3
Authors: GARG K. B. , HEINONEN M. , NORDBLAD P. , DALELA S. D. , PANWAR N. , SEN V. , AGARWAL S. K. , SHARMA NEHA
Published: May 2011

We have thoroughly investigated the oxygen loss in PrMnO 3 and BaMnO 3, the end members of the AMnO 3 system, on in situ heating in a reducing atmosphere. This was done to drive some oxygen out from them and thus possibly alter the valence of the Mn cation. Sample characterization was done through X-ray diffraction and SEM measurements. The core-level photoemission point to oxygen loss from only BaMnO 3 changing some of Mn 4+ to Mn 3+ in it, transfer of some spectral weight to the highly localized Fehrenbacher–Rice states and an increased Mn 3d – O 2p hybridization. Magnetization measurements show that at low temperatures, the samples depict a canted antiferromagnetic ordering.
THE EFFECT OF THE DIPOLE–QUADRUPOLE INTERACTION ON THE PHASE SPACE OF THE SPIN-1 ISING MODEL
Authors: ÖZKAN A. , KUTLU B.
Published: May 2011

The spin-1 Ising model with the dipole–quadrupole interaction (ℓ = L/J) has been simulated using a cellular automaton (CA) algorithm improved from the Creutz cellular automaton (CCA) for a face-centered cubic (fcc) lattice. The simulations have been made for different ℓ values at the reentrant phase transition and the special points such as the tricritical point (k = K/J = 0, d = D/J = 5.7) and the critical end point (k = -0.9, d = 0.7). The simulation results show that the model has the dense ferromagnetic (df, df(+), df(-)) and the ferromagnetic (F, F(+), F(-)) phases with the dipole–quadrupole interaction. The type and the order of the phase transitions change for the nonzero values of ℓ on the special points. Furthermore, the effect of ℓ is similar with the effect of the external magnetic field (h).
HILDEN BRAID GROUPS
Authors: BELLINGERI P. , CATTABRIGA A.
Published: May 2011

Let Hgbe a genus g handlebody and MCG2n( Tg) be the group of the isotopy classes of orientation preserving homeomorphisms of Tg= ∂ Hg, fixing a given set of 2n points. In this paper we study two particular subgroups of MCG2n( Tg) which generalize Hilden groups defined by Hilden in [Generators for two groups related to the braid groups, Pacific J. Math.59 (1975) 475–486]. As well as Hilden groups are related to plat closures of braids, these generalizations are related to Heegaard splittings of manifolds and to bridge decompositions of links. Connections between these subgroups and motion groups of links in closed 3-manifolds are also provided.
EQUIVARIANT COLORED 𝔰𝔩(N)-HOMOLOGY FOR LINKS
Authors: WU HAO
Published: May 2011

In this sequel to [A colored 𝔰𝔩(N)-homology for links in S3, preprint (2009), arXiv:0907.0695v5], we construct an equivariant colored 𝔰𝔩(N)-homology for links, which generalizes both the above mentioned paper and the paper by [D. Krasner, Equivariant sl(n)-link homology, preprint (2008), arXiv:0804.3751v2]. The construction is a straightforward generalization of the paper, [A colored 𝔰𝔩(N)-homology for links in S3]. The proof of invariance is based on a simple observation which allows us to translate the proof in the above mentioned paper into the new setting.

As an application, we prove that deformations over ℂ of the colored 𝔰𝔩(N)-homology are link invariants. We also construct a spectral sequence connecting the colored 𝔰𝔩(N)-homology to its deformations over ℂ, which generalizes the spectral sequence given in the papers by [B. Gornik, Note on Khovanov link cohomology, preprint (2004), arXiv:math.QA/0402266 and E. Lee, An endomorphism of the Khovanov invariant, Adv. Math.197(2) (2005) 554–586].
ON KNOTS WITH INFINITE SMOOTH CONCORDANCE ORDER
Authors: LEVINE ADAM SIMON
Published: May 2011

We use the Heegaard Floer obstructions defined by Grigsby, Ruberman, and Strle to show that forty-five of the sixty-six knots through eleven crossings whose concordance orders were previously unknown have infinite concordance order.
AVERAGE CROSSING NUMBER, TOTAL CURVATURE AND ROPELENGTH OF THICK KNOTS
Authors: ERNST C. , POR A.
Published: May 2011

Let K be a smooth knot of unit thickness embedded in the space [Formula: see text] with length L(K) and total curvature κ(K). Then [Formula: see text] where acn (K) is the average crossing number of the embedded knot K and c > 0 is a constant independent of the knot K. This relationship had been conjectured in [G. Buck and J. Simon, Total curvature and packing of knots, Topology Appl.154 (2007) 192–204] where it is shown that the square root power on the curvature is the lowest possible. In the last section we give several examples to illustrate some relationships between the three quantities average crossing number, total curvature and ropelength.
HIGH DISTANCE KNOTS IN CLOSED 3-MANIFOLDS
Authors: CAMPISI MARION MOORE , RATHBUN MATT
Published: May 2011

Let M be a closed 3-manifold with a given Heegaard splitting. We show that after a single stabilization, some core of the stabilized splitting has arbitrarily high distance with respect to the splitting surface. This generalizes a result of Minsky, Moriah, and Schleimer for knots in S3. We also show that in the complex of curves, handlebody sets are either coarsely distinct or identical. We define the coarse mapping class group of a Heegaard splitting, and show that if (S, V, W) is a Heegaard splitting of genus ≥2, then the coarse mapping class group of (S, V, W) is isomorphic to the mapping class group of (S, V, W).
BRAIDING SURFACE LINKS WHICH ARE COVERINGS OVER THE STANDARD TORUS
Authors: NAKAMURA INASA
Published: May 2011

We consider a surface link in the 4-space which can be presented by a simple branched covering over the standard torus, which we call a torus-covering link. Torus-covering links include spun T2-knots and turned spun T2-knots. In this paper we braid a torus-covering link over the standard 2-sphere. This gives an upper estimate of the braid index of a torus-covering link. In particular we show that the turned spun T2-knot of the torus (2, p)-knot has the braid index four.
MINIMUM NUMBER OF FOX COLORS FOR SMALL PRIMES
Authors: LOPES PEDRO , MATIAS JOÃO
Published: May 2011

This article concerns exact results on the minimum number of colors of a Fox coloring over the integers modulo r, of a link with non-null determinant.

Specifically, we prove that whenever the least prime divisor of the determinant of such a link and the modulus r is 2, 3, 5, or 7, then the minimum number of colors is 2, 3, 4, or 4 (respectively) and conversely.

We are thus led to conjecture that for each prime p there exists a unique positive integer, mp, with the following property. For any link L of non-null determinant and any modulus r such that p is the least prime divisor of the determinant of L and the modulus r, the minimum number of colors of L modulo r is mp.
TWISTED TORUS KNOTS T(p, q;kq, s) ARE CABLE KNOTS
Authors: LEE SANGYOP
Published: May 2011

We determine the knot types of twisted torus knots T(p, q;r, s) when q divides r. We also determine their tunnel numbers.
DETERMINING THE COMPONENT NUMBER OF LINKS CORRESPONDING TO TRIANGULAR AND HONEYCOMB LATTICES
Authors: JIANG LEPING , JIN XIAN'AN , DENG KECAI
Published: May 2011

There is a classical correspondence between edge-signed plane graphs and link diagrams. Determining component number of links corresponding to plane graphs may be one of the first problems in studying links by using graphs. There has been several early studies in this aspect, for example, the component number of links formed from 2-dimensional square lattices (44) has been determined. In this paper, we determine the component number of links corresponding to 2-dimensional triangular (36) and honeycomb (63) lattices with free or cyclic boundary condition.
VIRTUAL BRAID GROUPS OF TYPE B AND WEAK CATEGORIFICATION
Authors: THIEL ANNE-LAURE
Published: May 2011

We define virtual braid groups of type B and construct a morphism from such a group to the group of isomorphism classes of some invertible complexes of bimodules up to homotopy.
ON THE KNOT FLOER HOMOLOGY OF A CLASS OF SATELLITE KNOTS
Authors: BAO YUANYUAN
Published: May 2011

Knot Floer homology is an invariant for knots in the three-sphere for which the Euler characteristic is the Alexander–Conway polynomial of the knot. The aim of this paper is to study this homology for a class of satellite knots, so as to see how a certain relation between the Alexander–Conway polynomials of the satellite, companion and pattern is generalized on the level of the knot Floer homology. We also use our observations to study a classical geometric invariant, the Seifert genus, of our satellite knots.
SELF-ADJOINT REPRESENTATIONS OF BRAID GROUPS
Authors: EGEA CLAUDIA MARÍA , GALINA ESTHER
Published: May 2011

We give a method to construct new self-adjoint representations of 𝔹n of finite dimension. In particular, we give a family of irreducible self-adjoint representations of dimension arbitrarily large. Moreover we give sufficient condition for a representation to be constructed with this method.
CONSTRUCTION OF MRA E-TIGHT FRAME WAVELETS, MULTIPLIERS AND CONNECTIVITY PROPERTIES
Authors: LI DENG-FENG , CHENG JUN-FANG
Published: May 2011

A method that constructs an MRA E-tight frame wavelet by using a generalized low pass E-filter is given, and it is showed that all of MRA E-tight frame wavelets can be obtained via the method, where the dilation matrix E is the quincunx matrix or the matrix consists of (0, 1)T and (2, 0)T. Furthermore, the properties of MRA E-tight frame wavelet multipliers as well as E-pseudoscaling function multipliers and generalized low pass E-filter multipliers are characterized. In addition, as an application of these multipliers, we discuss the connectivity of the set of all MRA E-tight frame wavelets in L2(R2).
BIORTHOGONAL WAVELETS WITH SIX-FOLD AXIAL SYMMETRY FOR HEXAGONAL DATA AND TRIANGLE SURFACE MULTIRESOLUTION PROCESSING
Authors: JIANG QINGTANG
Published: May 2011

This paper discusses the construction of highly symmetric compactly supported wavelets for hexagonal data/image and triangle surface multiresolution processing. Recently, hexagonal image processing has attracted attention. Compared with the conventional square lattice, the hexagonal lattice has several advantages, including that it has higher symmetry. It is desirable that the filter banks for hexagonal data also have high symmetry which is pertinent to the symmetric structure of the hexagonal lattice. The high symmetry of filter banks and wavelets not only leads to simpler algorithms and efficient computations, it also has the potential application for the texture segmentation of hexagonal data. While in the field of computer-aided geometric design (CAGD), when the filter banks are used for surface multiresolution processing, it is required that the corresponding decomposition and reconstruction algorithms for regular vertices have high symmetry, which make it possible to design the corresponding multiresolution algorithms for extraordinary vertices.

In this paper we study the construction of six-fold axial symmetric biorthogonal filter banks and the associated wavelets, with both the dyadic and [Formula: see text]-refinements. The constructed filter banks have the desirable symmetry for hexagonal data processing. By associating the outputs (after one-level multiresolution decomposition) appropriately with the nodes of the regular triangular mesh with which the input data is associated (sampled), we represent multiresolution analysis and synthesis algorithms as templates. The six-fold axial symmetric filter banks constructed in this paper result in algorithm templates with desirable symmetry for triangle surface processing.
A WAVELET METHOD COUPLED WITH QUASI-SELF-SIMILAR STOCHASTIC PROCESSES FOR TIME SERIES APPROXIMATION
Authors: HAMRITA MOHAMED ESSAIED , ABDALLAH NIDHAL BEN , MABROUK ANOUAR BEN
Published: May 2011

Scaling laws and generally self-similar structures are now well known facts in financial time series. Furthermore, these signals are characterized by the presence of stochastic behavior allowing their analysis with pure functional methods being incomplete. In the present paper, some existing models are reviewed and modified, based on wavelet theory and self-similarity, to recover multi-scaling cases for approximating financial signals. The resulting models are then tested on some empirical examples and analyzed for error estimates.
Activation of P2Y receptors causes strong and persistent shrinkage of C11-MDCK renal epithelial cells
Authors: Koltsova Svetlana V. , Platonova Alexandra , Maksimov Georgy V. , Mongin Alexander A. , Grygorczyk Ryszard , Orlov Sergei N.
Published: May 2011

Purinergic receptors activate diverse signaling cascades and regulate the activity of cell volume-sensitive ion transporters. However, the effects of ATP and other agonists of P2 receptors on cell volume dynamics are only scarcely studied. In the present work, we used the recently developed dual-image surface reconstruction technique to explore the influence of purinergic agonists on cell volume in the C11-Madin-Darby canine kidney cell line resembling intercalated cells from kidney collecting ducts. Unexpectedly, we found that ATP and UTP triggered very robust (55–60%) cell shrinkage that lasted up to 2 h after agonist washout. Purinergic regulation of cell volume required increases in intracellular Ca2+ and could be partially mimicked by the Ca2+-ionophore ionomycin or activation of protein kinase C by 4β-phorbol 12-myristate 13-acetate. Cell shrinkage was accompanied by strong reductions in intracellular K+ and Cl− content measured using steady-state 86Rb+ and 36Cl− distribution. Both shrinkage and ion efflux in ATP-treated cells were prevented by the anion channel blocker 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) and by the BKCa channel inhibitors charybdotoxin, iberiotoxin, and paxilline. To evaluate the significance of cell-volume changes in purinergic signaling, we measured the impact of ATP on the expression of the immediate-early gene c-Fos. Thirty-minute treatment with ATP increased c-Fos immunoreactivity by approximately fivefold, an effect that was strongly inhibited by charybdotoxin and completely prevented by NPPB. Overall, our findings suggest that ATP-induced cell-volume changes are partially responsible for the physiological actions of purinergic agonists.
Estrogen-related receptor α regulates skeletal myocyte differentiation via modulation of the ERK MAP kinase pathway
Authors: Murray Jennifer , Huss Janice M.
Published: May 2011

Myocyte differentiation involves complex interactions between signal transduction pathways and transcription factors. The estrogen-related receptors (ERRs) regulate energy substrate uptake, mitochondrial respiration, and biogenesis and may target structural gene programs in striated muscle. However, ERRα's role in regulating myocyte differentiation is not known. ERRα and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) are coordinately upregulated with metabolic and skeletal muscle-specific genes early in myogenesis. We analyzed effects of ERRα overexpression and loss of function in myogenic models. In C2C12 myocytes ERRα overexpression accelerated differentiation, whereas XCT790 treatment delayed myogenesis and resulted in myotubes with fewer mitochondria and disorganized sarcomeres. ERRα−/− primary myocytes showed delayed myogenesis, resulting in structurally immature myotubes with reduced sarcomeric assembly and mitochondrial function. However, sarcomeric and metabolic gene expression was unaffected or upregulated in ERRα−/− cells. Instead, ERRα−/− myocytes exhibited aberrant ERK activation early in myogenesis, consistent with delayed myotube formation. XCT790 treatment also increased ERK phosphorylation in C2C12, whereas ERRα overexpression decreased early ERK activation, consistent with the opposing effects of these treatments on differentiation. The transient induction of MAP kinase phosphatase-1 (MKP-1), which mediates ERK dephosphorylation at the onset of myogenesis, was lost in ERRα−/− myocytes and in XCT790-treated C2C12. The ERRα-PGC-1α complex activates the Dusp1 gene, which encodes MKP-1, and ERRα occupies the proximal 5′ regulatory region during early differentiation in C2C12 myocytes. Finally, treatment of ERRα−/− myocytes with MEK inhibitors rescued normal ERK signaling and myogenesis. Collectively, these data demonstrate that ERRα is required for normal skeletal myocyte differentiation via modulation of MAP kinase signaling.
Ion channels and transporters in cancer. 3. Ion channels in the tumor cell-microenvironment cross talk
Authors: Arcangeli Annarosa
Published: May 2011

The traditional view of cancer as a collection of proliferating cells must be reconsidered, and cancer must be viewed as a “tissue” constituted by both transformed cells and a heterogeneous microenvironment, that tumor cells construct and remodel during multistep tumorigenesis. The “tumor microenvironment” (TM) is formed by mesenchymal, endothelial, and immune cells immersed in a network of extracellular matrix (ECM) proteins and soluble factors. The TM strongly contributes to tumor progression, through long distance, cell-to-cell or cell-to-matrix signals, which influence different aspects of tumor cell behavior. Understanding the relationships among the different components of the cancer tissue is crucial to design and develop new therapeutic strategies. Ion channels are emerging as relevant players in the cross talk between tumor cells and their TM. Ion channels are expressed on tumor cells, as well as in the different cellular components of the TM. In all these cells, ion channels are in a strategic position to sense and transmit extracellular signals into the intracellular machinery. Often, this transmission is mediated by integrin adhesion receptors, which can be functional partners of ion channels since they form molecular complexes with the channel protein in the context of the plasma membrane. The same relevant role is exerted by ion transporters, which also contribute to determine two facets of the cancer tissue: hypoxia and the acidic extracellular pH. On the whole, it is conceivable to prospect the targeting of ion channels for new therapeutic strategies aimed at better controlling the malignant progression of the cancer tissue.
Ischemia-induced stimulation of Na-K-Cl cotransport in cerebral microvascular endothelial cells involves AMP kinase
Authors: Wallace Breanna K. , Foroutan Shahin , O'Donnell Martha E.
Published: May 2011

Increased blood-brain barrier (BBB) Na-K-Cl cotransporter activity appears to contribute to cerebral edema formation during ischemic stroke. We have shown previously that inhibition of BBB Na-K-Cl cotransporter activity reduces edema and infarct in the rat middle cerebral artery occlusion (MCAO) model of ischemic stroke. We have also shown that the BBB cotransporter is stimulated by the ischemic factors hypoxia, aglycemia, and arginine vasopressin (AVP), although the mechanisms responsible are not well understood. AMP-activated protein kinase (AMPK), a key mediator of cell responses to stress, can be activated by a variety of stresses, including ischemia, hypoxia, and aglycemia. Previous studies have shown that the AMPK inhibitor Compound C significantly reduces infarct in mouse MCAO. The present study was conducted to evaluate the possibility that AMPK participates in ischemic factor-induced stimulation of the BBB Na-K-Cl cotransporter. Cerebral microvascular endothelial cells (CMEC) were assessed for Na-K-Cl cotransporter activity as bumetanide-sensitive 86Rb influx. AMPK activity was assessed by Western blot analysis and immunofluorescence methods using antibodies that detect total versus phosphorylated (activated) AMPK. We found that hypoxia (7% and 2% O2), aglycemia, AVP, and oxygen-glucose deprivation (5- to 120-min exposures) increase activation of AMPK. We also found that Compound C inhibition of AMPK reduces hypoxia-, aglycemia-, and AVP-induced stimulation of CMEC Na-K-Cl cotransporter activity. Confocal immunofluorescence of perfusion-fixed rat brain slices revealed the presence of AMPK, both total and phosphorylated kinase, in BBB in situ of both control and ischemic brain. These findings suggest that ischemic factor stimulation of the BBB Na-K-Cl cotransporter involves activation of AMPK.
Decreasing temperature shifts hippocampal function from memory formation to modulation of hibernation bout duration in Syrian hamsters
Authors: Arant Ryan J. , Goo Marisa S. , Gill Phoebe D. , Nguyen Yen , Watson Katherine D. , Hamilton Jock S. , Horowitz John M. , Horwitz Barbara A.
Published: May 2011

Previous studies in hibernating species have characterized two forms of neural plasticity in the hippocampus, long-term potentiation (LTP) and its reversal, depotentiation, but not de novo long-term depression (LTD), which is also associated with memory formation. Studies have also shown that histamine injected into the hippocampus prolonged hibernation bout duration. However, spillover into the ventricles may have affected brain stem regions, not the hippocampus. Here, we tested the hypothesis that decreased brain temperature shifts the major function of the hippocampus in the Syrian hamster ( Mesocricetus auratus) from one of memory formation (via LTP, depotentiation, and de novo LTD) to increasing hibernation bout duration. We found reduced evoked responses in hippocampal CA1 pyramidal neurons following low-frequency stimulation in young (<30 days old) and adult (>60 days old) hamsters, indicating that de novo LTD was generated in hippocampal slices from both pups and adults at temperatures >20°C. However, at temperatures below 20°C, synchronization of neural assemblies (a requirement for LTD generation) was markedly degraded, implying that de novo LTD cannot be generated in hibernating hamsters. Nonetheless, even at temperatures below 16°C, pyramidal neurons could still generate action potentials that may traverse a neural pathway, suppressing the ascending arousal system (ARS). In addition, histamine increased the excitability of these pyramidal cells. Taken together, these findings are consistent with the hypothesis that hippocampal circuits remain operational at low brain temperatures in Syrian hamsters and suppress the ARS to prolong bout duration, even though memory formation is muted at these low temperatures.
Hsp90 and angiogenesis in bone disorders—lessons from the avian growth plate
Authors: Herzog Ayelet , Genin Olga , Hasdai Ahron , Shinder Dima , Pines Mark
Published: May 2011

Thiram-induced tibial dyschondroplasia (TD) and vitamin-D deficiency rickets are avian bone disorders of different etiologies characterized by abnormal chondrocyte differentiation, enlarged and unvascularized growth plates, and lameness. Heat-shock protein 90 (Hsp90) is a proangiogenic factor in mammalian tissues and in tumors; therefore, Hsp90 inhibitors were developed as antiangiogenic factors. In this study, we evaluated the association between Hsp90, hypoxia, and angiogenesis in the chick growth plate. Administration of the Hsp90 inhibitor to TD- and rickets-afflicted chicks at the time of induction resulted in reduction in growth-plate size and, contrary to its antiangiogenic effect in tumors, a major invasion of blood vessels occurred in the growth plates. This was the result of upregulation of the VEGF receptor Flk-1, the major rate-limiting factor of vascularization in TD and rickets. In addition, the abnormal chondrocyte differentiation, as characterized by collagen type II expression and alkaline phosphatase activity, and the changes in hypoxia-inducible factor-1α (HIF-1α) in both disorders were restored. All these changes resulted in prevention of lameness. Inhibition of Hsp90 activity reduced growth-plate size, increased vascularization, and mitigated lameness also in TD chicks with established lesions. In summary, this is the first reported demonstration of involvement of Hsp90 in chondrocyte differentiation and growth-plate vascularization. In contrast to the antiangiogenic effect of Hsp90 inhibitors observed in mammals, inhibition of Hsp90 activity in the unvascularized TD- and rickets-afflicted chicks resulted in activation of the angiogenic switch and reinstated normal growth-plate morphology.
Regulation of serum 1,25(OH)2Vitamin D3levels by fibroblast growth factor 23 is mediated by FGF receptors 3 and 4
Authors: Gattineni Jyothsna , Twombley Katherine , Goetz Regina , Mohammadi Moosa , Baum Michel
Published: May 2011

Fibroblast growth factor 23 (FGF23) is a phosphaturic hormone implicated in the pathogenesis of several hypophosphatemic disorders. FGF23 causes hypophosphatemia by decreasing the expression of sodium phosphate cotransporters (NaPi-2a and NaPi-2c) and decreasing serum 1,25(OH)2Vitamin D3levels. We previously showed that FGFR1 is the predominant receptor for the hypophosphatemic actions of FGF23 by decreasing renal NaPi-2a and 2c expression while the receptors regulating 1,25(OH)2Vitamin D3levels remained elusive. To determine the FGFRs regulating 1,25(OH)2Vitamin D3levels, we studied FGFR3−/−FGFR4−/−mice as these mice have shortened life span and are growth retarded similar to FGF23−/−and Klotho−/−mice. Baseline serum 1,25(OH)2Vitamin D3levels were elevated in the FGFR3−/−FGFR4−/−mice compared with wild-type mice (102.2 ± 14.8 vs. 266.0 ± 34.0 pmol/l; P = 0.001) as were the serum levels of FGF23. Administration of recombinant FGF23 had no effect on serum 1,25(OH)2Vitamin D3in the FGFR3−/−FGFR4−/−mice (173.4 ± 32.7 vs. 219.7 ± 56.5 pmol/l; vehicle vs. FGF23) while it reduced serum 1,25(OH)2Vitamin D3levels in wild-type mice. Administration of FGF23 to FGFR3−/−FGFR4−/−mice resulted in a decrease in serum parathyroid hormone (PTH) levels and an increase in serum phosphorus levels mediated by increased renal phosphate reabsorption. These data indicate that FGFR3 and 4 are the receptors that regulate serum 1,25(OH)2Vitamin D3levels in response to FGF23. In addition, when 1,25(OH)2Vitamin D3levels are not affected by FGF23, as in FGFR3−/−FGFR4−/−mice, a reduction in PTH can override the effects of FGF23 on renal phosphate transport.
History dependence of human muscle-fiber conduction velocity during voluntary isometric contractions
Authors: McGill Kevin C. , Lateva Zoia C.
Published: May 2011

The conduction velocity (CV) of a muscle fiber is affected by the fiber's discharge history going back ∼1 s. We investigated this dependence by measuring CV fluctuations during voluntary isometric contractions of the human brachioradialis muscle. We recorded electromyogram (EMG) signals simultaneously from multiple intramuscular electrodes, identified potentials belonging to the same motor unit using EMG decomposition, and estimated the CV of each discharge from the interpotential interval. In 12 of 14 subjects, CV increased by ∼10% during the first second after recruitment and then fluctuated by about ±2% in a way that mirrored the fluctuations in the instantaneous firing rate. The CV profile could be precisely described in terms of the discharge history by a simple mathematical model. In the other two subjects, and one subject retested after cooling the arm, the CV fluctuations were inversely correlated with instantaneous firing rate. In all subjects, CV was additionally affected by very short interdischarge intervals (<25 ms): it was increased in doublets at recruitment, but decreased in doublets during continuous firing and after short interdischarge intervals in doubly innervated fibers. CV also exhibited a slow trend of about −0.05%/s that did not depend on the immediate discharge history. We suggest that measurements of CV fluctuations during voluntary contractions, or during stimulation protocols that involve longer and more complex stimulation patterns than are currently being used, may provide a sensitive approach for estimating the dynamic characteristics of ion channels in the human muscle-fiber membrane.
Effects of exercise training on coronary collateralization and control of collateral resistance
Authors: Heaps Cristine L. , Parker Janet L.
Published: May 2011

Coronary collateral vessels serve as a natural protective mechanism to provide coronary flow to ischemic myocardium secondary to critical coronary artery stenosis. The innate collateral circulation of the normal human heart is typically minimal and considerable variability occurs in extent of collateralization in coronary artery disease patients. A well-developed collateral circulation has been documented to exert protective effects upon myocardial perfusion, contractile function, infarct size, and electrocardiographic abnormalities. Thus therapeutic augmentation of collateral vessel development and/or functional adaptations in collateral and collateral-dependent arteries to reduce resistance into the ischemic myocardium represent a desirable goal in the management of coronary artery disease. Tremendous evidence has provided documentation for the therapeutic benefits of exercise training programs in patients with coronary artery disease (and collateralization); mechanisms that underlie these benefits are numerous and multifaceted, and currently under investigation in multiple laboratories worldwide. The role of enhanced collateralization as a major beneficial contributor has not been fully resolved. This topical review highlights literature that examines the effects of exercise training on collateralization in the diseased heart, as well as effects of exercise training on vascular endothelial and smooth muscle control of regional coronary tone in the collateralized heart. Future directions for research in this area involve further delineation of cellular/molecular mechanisms involved in effects of exercise training on collateralized myocardium, as well as development of novel therapies based on emerging concepts regarding exercise training and coronary artery disease.
Sensorimotor adaptation of point-to-point arm movements after spaceflight: the role of internal representation of gravity force in trajectory planning
Authors: Gaveau Jérémie , Paizis Christos , Berret Bastien , Pozzo Thierry , Papaxanthis Charalambos
Published: May 2011

After an exposure to weightlessness, the central nervous system operates under new dynamic and sensory contexts. To find optimal solutions for rapid adaptation, cosmonauts have to decide whether parameters from the world or their body have changed and to estimate their properties. Here, we investigated sensorimotor adaptation after a spaceflight of 10 days. Five cosmonauts performed forward point-to-point arm movements in the sagittal plane 40 days before and 24 and 72 h after the spaceflight. We found that, whereas the shape of hand velocity profiles remained unaffected after the spaceflight, hand path curvature significantly increased 1 day after landing and returned to the preflight level on the third day. Control experiments, carried out by 10 subjects under normal gravity conditions, showed that loading the arm with varying loads (from 0.3 to 1.350 kg) did not affect path curvature. Therefore, changes in path curvature after spaceflight cannot be the outcome of a control process based on the subjective feeling that arm inertia was increased. By performing optimal control simulations, we found that arm kinematics after exposure to microgravity corresponded to a planning process that overestimated the gravity level and optimized movements in a hypergravity environment (∼1.4 g). With time and practice, the sensorimotor system was recalibrated to Earth's gravity conditions, and cosmonauts progressively generated accurate estimations of the body state, gravity level, and sensory consequences of the motor commands (72 h). These observations provide novel insights into how the central nervous system evaluates body (inertia) and environmental (gravity) states during sensorimotor adaptation of point-to-point arm movements after an exposure to weightlessness.
Behavioral significance of hippocampal theta oscillations: looking elsewhere to find the right answers
Authors: Young Calvin K.
Published: May 2011

The function of hippocampal theta oscillations has been subjected to constant speculation. Dynamic coupling of theta field potentials and spiking activity between the hippocampus and extra-hippocampal structures emphasizes the importance of theta-frequency oscillations in global spike-timing precision in the brain. Recent advances in understanding theta coupling between distant brain structures are discussed and explored in this article.
Binaural sensitivity changes between cortical on and off responses
Authors: Hartley Douglas E. H. , Dahmen Johannes C. , King Andrew J. , Schnupp Jan W. H.
Published: May 2011

Neurons exhibiting on and off responses with different frequency tuning have previously been described in the primary auditory cortex (A1) of anesthetized and awake animals, but it is unknown whether other tuning properties, including sensitivity to binaural localization cues, also differ between on and off responses. We measured the sensitivity of A1 neurons in anesthetized ferrets to 1) interaural level differences (ILDs), using unmodulated broadband noise with varying ILDs and average binaural levels, and 2) interaural time delays (ITDs), using sinusoidally amplitude-modulated broadband noise with varying envelope ITDs. We also assessed fine-structure ITD sensitivity and frequency tuning, using pure-tone stimuli. Neurons most commonly responded to stimulus onset only, but purely off responses and on-off responses were also recorded. Of the units exhibiting significant binaural sensitivity nearly one-quarter showed binaural sensitivity in both on and off responses, but in almost all (∼97%) of these units the binaural tuning of the on responses differed significantly from that seen in the off responses. Moreover, averaged, normalized ILD and ITD tuning curves calculated from all units showing significant sensitivity to binaural cues indicated that on and off responses displayed different sensitivity patterns across the population. A principal component analysis of ITD response functions suggested a continuous cortical distribution of binaural sensitivity, rather than discrete response classes. Rather than reflecting a release from inhibition without any functional significance, we propose that binaural off responses may be important to cortical encoding of sound-source location.
Whole‐Body Vibration Sensor Calibration Using a Six‐Degree of Freedom Robot
Authors: Cation Sarah , Oliver Michele , Jack Robert Joel , Dickey James P. , Lee Shee Natasha
Published: May 2011

Exposure to whole‐body vibration (WBV) is associated with a wide variety of health disorders and as a result WBV levels are frequently assessed. Literature outlining WBV accelerations rarely address the calibration techniques and procedures used for WBV sensors to any depth, nor are any detailed information provided regarding such procedures or sensor calibration ranges. The purpose of this paper is to describe a calibration method for a 6 DOF transducer using a hexapod robot. Also described is a separate motion capture technique used to verify the calibration for acceleration values obtained which were outside the robot calibration range in order to include an acceptable calibration range for WBV environments. The sensor calibrated in this study used linear (Y = mX) calibration equations resulting in r2 values greater than 0.97 for maximum and minimum acceleration amplitudes of up to ±8 m/s2 and maximum and minimum velocity amplitudes up to ±100°/s. The motion capture technique verified that the translational calibrations held for accelerations up to ±4 g. Thus, the calibration procedures were shown to calibrate the sensor through the expected range for 6‐DOF WBV field measurements for off‐road vehicles even when subjected to shocks as a result of high speed travel over rough terrain.
Prolonged Refractory Hypotension following Combined Amlodipine and Losartan Ingestion Responsive to Metaraminol
Authors: Plumb James O. M. , Stewart Craig , Eddleston Michael , de Beer Thearina
Published: May 2011

Introduction. Overdose with the calcium channel blocker amlodipine can cause profound hypotension that may be exacerbated by the concurrent ingestion of an angiotensin II receptor antagonist. Best management of such overdoses is uncertain although the use of hyperinsulinaemia-euglycaemia (HIE) has been recommended.Case report. We report a case of mixed amlodipine and losartan overdose in a 50-year-old lady. Severe hypotension was resistant to conventional vasopressors and high-dose insulin/euglycaemia, but did respond to a metaraminol infusion.Conclusion. A trial of metaraminol early in severe cases of calcium channel blocker and angiotensin II receptor antagonist toxicity may be of benefit, especially when conventional ionotropic treatment measures are failing.
Structure and Magnetic Properties ofY3−xErxFe5O12(x=0.2,1.0, and 2.0) Thin Films Prepared by Sol-Gel Method
Authors: Shaiboub Ramadan , Ibrahim Noor Baa'yah , Abdullah Mustaffa , Abdulhade Ftema
Published: May 2011

NanoparticlesY3−xErxFe5O12(x=0.2, 1.0, and 2.0) thin films were prepared by sol-gel method and treated at 800, 900, and 1000∘C, respectively, for 2 h. The films have single phase garnet structure and the sizes of particles are in the range of 44 to 83 nm. The magnetic measurements show that the saturation magnetization decreased with increasing of Er concentration for all samples treated at different annealing temperatures. The saturation magnetization increased with the particle size due to the enhancement of the surface spin effect. The coercivity initially decreased forx=1.0and then increased forx=2.0with increasing annealing temperature.
The Application of Thermosensitive Nanocarriers in Controlled Drug Delivery
Authors: Shao Pengyu , Wang Bochu , Wang Yazhou , Li Jun , Zhang Yiqiong
Published: May 2011

Thermosensitive nanocarriers as the “smart” drug delivery systems have shown tremendous promise in the field of controlled drug delivery due to their special property. Thermosensitive nanocarriers with long circulation properties can accumulate in the pathological sites by enhanced permeability and retention (EPR) effect or attach targeting ligands to the surface of the nanocarriers, and the drug release rates of these pharmaceutical nanocarriers can be adjusted in response to thermal variability of the environment. In this paper, we first discuss the classification of thermosensitive polymer according to their functional properties in thermosensitive nanocarriers. On the basis of this, our main purposes are focused on reviewing the characteristics of various thermosensitive nanocarriers including the strategies for their functionalization, thermosensitive behavior, or site-specific targeting. Furthermore, the paper discusses the current and future trends of the thermosensitive nanocarriers in controlled drug delivery.
Management of an Oral Ingestion of Transdermal Fentanyl Patches: A Case Report and Literature Review
Authors: Faust Andrew C. , Terpolilli Ralph , Hughes Darrel W.
Published: May 2011

Purpose. Fentanyl is available as a transdermal system for the treatment of chronic pain in opioid-tolerant patients; however, it carries a black box warning due to both the potency of the product and the potential for abuse. In this report, we describe a case of transbuccal and gastrointestinal ingestion of fentanyl patches and the management of such ingestion.Summary. A 32-year-old man was brought to the emergency department (ED) via emergency medical services for toxic ingestion and suicide attempt. The patient chewed and ingested two illegally purchased transdermal fentanyl patches. In the ED, the patient was obtunded, dizzy and drowsy. Initial vital signs showed the patient to be afebrile and normotensive with a heart rate of 63, respiratory rate of 16, and oxygen saturation of 100% on 2 liters nasal cannula after administration of 2 milligrams of intravenous naloxone. The patient was treated with whole bowel irrigation and continuous intravenous naloxone infusion for approximately 48 hours without complications.Conclusion. Despite numerous case reports describing oral ingestion of fentanyl patches, information on the management of such intoxication is lacking. We report successful management of such a case utilizing whole bowel irrigation along with intravenous push and continuous infusion naloxone.
Hopf Bifurcation Analysis for the van der Pol Equation with Discrete and Distributed Delays
Authors: Zhou Xiaobing , Jiang Murong , Cai Xiaomei
Published: May 2011

We consider the van der Pol equation with discrete and distributed delays. Linear
stability of this equation is investigated by analyzing the transcendental characteristic equation of
its linearized equation. It is found that this equation undergoes a sequence of Hopf bifurcations
by choosing the discrete time delay as a bifurcation parameter. In addition, the properties of Hopf
bifurcation were analyzed in detail by applying the center manifold theorem and the normal form theory. Finally, some numerical simulations are performed to illustrate and verify the theoretical analysis.
Efficacy and Tolerability of Intramuscular Dexketoprofen in Postoperative Pain Management following Hernia Repair Surgery
Authors: Jamdade P. T. , Porwal A. , Shinde J. V. , Erram S. S. , Kamat V. V. , Karmarkar P. S. , Bhagtani K. , Dhorepatil S. , Irpatgire R. , Bhagat H. , Kolte S. S. , Shirure P. A.
Published: May 2011

Objective. To evaluate the safety and efficacy of intramuscular dexketoprofen for postoperative pain in patients undergoing hernia surgery.Methodology. Total 202 patients received single intramuscular injection of dexketoprofen 50 mg or diclofenac 50 mg postoperatively. The pain intensity (PI) was self-evaluated by patients on VAS at baseline 1, 2, 4, 6, and 8 hours. The efficacy parameters were number of responders, difference in PI (PID) at 8 hours, sum of analogue of pain intensity differences (SAPID), and onset and duration of analgesia. Tolerability assessment was done by global evaluation and adverse events in each group.Results. Dexketoprofen showed superior efficacy in terms of number of responders (P=.007), PID at 8 hours (P=.02), and SAPID0–8 hours(P<.0001). It also showed faster onset of action (42 minutes) and longer duration of action (6.5 hours). The adverse events were comparable in both groups.Conclusion. Single dose of dexketoprofen trometamol 50 mg given intramuscularly provided faster, better, and longer duration of analgesia in postoperative patients of hernia repair surgery than diclofenac 50 mg, with comparable safety.