bluuebunny/crossref_metadata_2025 huggingface dataset:
Preclinical Studies of a Modified Vaccinia Virus Ankara-Based HIV Candidate Vaccine: Antigen Presentation and Antiviral Effect
Authors: Brandler Samantha , Lepelley Alice , Desdouits Marion , Guivel-Benhassine Florence , Ceccaldi Pierre-Emmanuel , Lévy Yves , Schwartz Olivier , Moris Arnaud
Published: March 2010

Poxvirus-based human immunodeficiency virus (HIV) vaccine candidates are currently under evaluation in preclinical and clinical trials. Modified vaccinia virus Ankara (MVA) vectors have excellent safety and immunogenicity records, but their behavior in human cell cultures remains only partly characterized. We studied here various virological and immunological aspects of the interactions of MVA-HIV, a vaccine candidate developed by the French National Agency for AIDS Research (ANRS), with primary human cells. We report that MVA-HIV infects and drives Gag expression in primary macrophages, dendritic cells (DCs), and epithelial and muscle cells. MVA-HIV-infected DCs matured, efficiently presented Gag, Pol, and Nef antigens, and activated HIV-specific cytotoxic T lymphocytes (CTLs). As expected with this type of vector, infection was cytopathic and led to DC apoptosis. Coculture of MVA-HIV-infected epithelial cells or myotubes with DCs promoted efficient Gag antigen major histocompatibility complex class I (MHC-I) cross-presentation without inducing direct infection and death of DCs. Antigen-presenting cells (APCs) infected with MVA-HIV also activated HIV-specific CD4
+
T cells. Moreover, exposure of DCs to MVA-HIV or to MVA-HIV-infected myotubes induced type I interferon (IFN) production and inhibited subsequent HIV replication and transfer to lymphocytes. Altogether, these results show that MVA-HIV promotes efficient MHC-I and MHC-II presentation of HIV antigens by APCs without facilitating HIV replication. Deciphering the immune responses to MVA in culture experiments will help in the design of innovative vaccine strategies.
Regulation of Epstein-Barr Virus OriP Replication by Poly(ADP-Ribose) Polymerase 1
Authors: Tempera Italo , Deng Zhong , Atanasiu Constandache , Chen Chi-Ju , D'Erme Maria , Lieberman Paul M.
Published: March 2010

Poly(ADP-ribose) polymerase (PARP) is an abundant, chromatin-associated, NAD-dependent enzyme that functions in multiple chromosomal processes, including DNA replication and chromatin remodeling. The Epstein-Barr virus (EBV) origin of plasmid replication (OriP) is a dynamic genetic element that confers stable episome maintenance, DNA replication initiation, and chromatin organization functions. OriP function depends on the EBV-encoded origin binding protein EBNA1. We have previously shown that EBNA1 is subject to negative regulation by poly(ADP-ribosyl)ation (PARylation). We now show that PARP1 physically associates with OriP in latently EBV-infected B cells. Short hairpin RNA depletion of PARP1 enhances OriP replication activity and increases EBNA1, origin recognition complex 2 (ORC2), and minichromosome maintenance complex (MCM) association with OriP. Pharmacological inhibitors of PARP1 enhance OriP plasmid maintenance and increase EBNA1, ORC2, and MCM3 occupancy at OriP. PARylation
in vitro
inhibits ORC2 recruitment and remodels telomere repeat factor (TRF) binding at the dyad symmetry (DS) element of OriP. Purified PARP1 can ribosylate EBNA1 at multiple sites throughout its amino terminus but not in the carboxy-terminal DNA binding domain. We also show that EBNA1 linking regions (LR1 and LR2) can bind directly to oligomers of PAR. We propose that PARP1-dependent PARylation of EBNA1 and adjacently bound TRF2 induces structural changes at the DS element that reduce EBNA1 DNA binding affinity and functional recruitment of ORC.
APOBEC3F and APOBEC3G Inhibit HIV-1 DNA Integration by Different Mechanisms
Authors: Mbisa Jean L. , Bu Wei , Pathak Vinay K.
Published: March 2010

APOBEC3F (A3F) and APBOBEC3G (A3G) both are host restriction factors that can potently inhibit human immunodeficiency virus type 1 (HIV-1) replication. Their antiviral activities are at least partially mediated by cytidine deamination, which causes lethal mutations of the viral genome. We recently showed that A3G blocks viral plus-strand DNA transfer and inhibits provirus establishment in the host genome (J. L. Mbisa, R. Barr, J. A. Thomas, N. Vandegraaff, I. J. Dorweiler, E. S. Svarovskaia, W. L. Brown, L. M. Mansky, R. J. Gorelick, R. S. Harris, A. Engelman, and V. K. Pathak, J. Virol. 81:7099-7110, 2007). Here, we investigated whether A3F similarly interferes with HIV-1 provirus formation. We observed that both A3F and A3G inhibit viral DNA synthesis and integration, but A3F is more potent than A3G in preventing viral DNA integration. We further investigated the mechanisms by which A3F and A3G block viral DNA integration by analyzing their effects on viral cDNA processing using Southern blot analysis. A3G generates a 6-bp extension at the viral U5 end of the 3′ long terminal repeat (3′-LTR), which is a poor substrate for integration; in contrast, A3F inhibits viral DNA integration by reducing the 3′ processing of viral DNA at both the U5 and U3 ends. Furthermore, we demonstrated that a functional C-terminal catalytic domain is more critical for A3G than A3F function in blocking HIV-1 provirus formation. Finally, we showed that A3F has a greater binding affinity for a viral 3′-LTR double-stranded DNA (dsDNA) oligonucleotide template than A3G. Taking these results together, we demonstrated that mechanisms utilized by A3F to prevent HIV-1 viral DNA integration were different from those of A3G, and that their target specificities and/or their affinities for dsDNA may contribute to their distinct mechanisms.
Species-Specific Antagonism of Host ISGylation by the Influenza B Virus NS1 Protein
Authors: Versteeg Gijs A. , Hale Benjamin G. , van Boheemen Sander , Wolff Thorsten , Lenschow Deborah J. , García-Sastre Adolfo
Published: March 2010

Interferon-stimulated expression and conjugation of the ubiquitin-like modifier ISG15 restricts replication of several viruses. Here, we established complete E1-activating, E2-conjugating, and E3 ligase-dependent expression systems for assaying both human and mouse ISGylation. We confirm that human HerC5, but not human HerC6, has ISG15 E3 ligase activity and identify mouse HerC6 as a bona fide ISG15 E3 ligase. Furthermore, we demonstrate that influenza B virus NS1 protein potently antagonizes human but not mouse ISGylation, a property dependent on B/NS1 binding the N-terminal domain of human but not mouse ISG15. Using chimeric human/mouse ISG15 constructs, we show that the B/NS1:ISG15 interaction is both necessary and sufficient to inhibit ISGylation regardless of the ligation machinery used. Inability to block ISGylation in certain species may contribute to limiting influenza B virus host range.
High Viremia Is Associated with High Levels of
In Vivo
Major Histocompatibility Complex Class I Downregulation in Rhesus Macaques Infected with Simian Immunodeficiency Virus SIVmac239
Authors: Friedrich Thomas C. , Piaskowski Shari M. , León Enrique J. , Furlott Jessica R. , Maness Nicholas J. , Weisgrau Kimberly L. , Mac Nair Caitlin E. , Weiler Andrea M. , Loffredo John T. , Reynolds Matthew R. , Williams K. Y. , Klimentidis Yann C. , Wilson Nancy A. , Allison David B. , Rakasz Eva G.
Published: March 2010

Human and simian immunodeficiency viruses (HIV and SIV) downregulate major histocompatibility complex class I (MHC-I) molecules from the surface of infected cells. Although this activity is conserved across viral isolates, its importance in AIDS pathogenesis is not clear. We therefore developed an assay to detect the level of MHC-I expression of SIV-infected cells directly
ex vivo
. Here we show that the extent of MHC-I downregulation is greatest in SIVmac239-infected macaques that never effectively control virus replication. Our results suggest that a high level of MHC-I downregulation is a hallmark of fast disease progression in SIV infection.
Induction of Reactive Oxygen Species by Human T-Cell Leukemia Virus Type 1 Tax Correlates with DNA Damage and Expression of Cellular Senescence Marker
Authors: Kinjo Takao , Ham-Terhune Julia , Peloponese Jean-Marie , Jeang Kuan-Teh
Published: March 2010

Human T-cell leukemia virus type 1 (HTLV-1) Tax affects cellular genomic stability and senescence. As yet, the mechanism(s) for these events caused by Tax is incompletely understood. Here, we show that Tax expression in primary human cells induces reactive oxygen species (ROS), which elicits DNA damage and the expression of senescence marker. Treatment with a ROS scavenger or knockdown of Tax expression by small interfering RNA (siRNA) abrogated Tax-induced DNA damage and the expression of senescence marker. Our data suggest that ROS induction explains Tax-induced cellular DNA damage and cellular senescence.
Avian Bornavirus Associated with Fatal Disease in Psittacine Birds
Authors: Staeheli Peter , Rinder Monika , Kaspers Bernd
Published: March 2010

Thanks to new technologies which enable rapid and unbiased screening for viral nucleic acids in clinical specimens, an impressive number of previously unknown viruses have recently been discovered. Two research groups independently identified a novel negative-strand RNA virus, now designated avian bornavirus (ABV), in parrots with proventricular dilatation disease (PDD), a severe lymphoplasmacytic ganglioneuritis of the gastrointestinal tract of psittacine birds that is frequently accompanied by encephalomyelitis. Since its discovery, ABV has been detected worldwide in many captive parrots and in one canary with PDD. ABV induced a PDD-like disease in experimentally infected cockatiels, strongly suggesting that ABV is highly pathogenic in psittacine birds. Until the discovery of ABV, the
Bornaviridae
family consisted of a single species, classical Borna disease virus (BDV), which is the causative agent of a progressive neurological disorder that affects primarily horses, sheep, and some other farm animals in central Europe. Although ABV and BDV share many biological features, there exist several interesting differences, which are discussed in this review.
Array-Based Transcript Profiling and Limiting-Dilution Reverse Transcription-PCR Analysis Identify Additional Latent Genes in Kaposi's Sarcoma-Associated Herpesvirus
Authors: Chandriani Sanjay , Ganem Don
Published: March 2010

Kaposi's sarcoma-associated herpesvirus (KSHV) is a B-lymphotropic herpesvirus strongly linked to both lymphoproliferative diseases and Kaposi's sarcoma. The viral latency program of KSHV is central to persistent infection and plays important roles in the pathogenesis of KSHV-related tumors. Up to six polypeptides and 18 microRNAs are known to be expressed in latency, but it is unclear if all major latency genes have been identified. Here, we have employed array-based transcript profiling and limiting-dilution reverse transcription-PCR (RT-PCR) methodologies to explore this issue in several KSHV-infected cell lines. Our results show that RNAs encoding the K1 protein are found at low levels in most latently infected cell lines. The gene encoding v-IL-6 is also expressed as a latent transcript in some contexts. Both genes encode powerful signaling molecules with particular relevance to B cell biology: K1 mimics signaling through the B cell receptor, and v-IL-6 promotes B cell survival. These data resolve earlier controversies about K1 and v-IL-6 expression and indicate that, in addition to core latency genes, some transcripts can be expressed in KSHV latency in a context-dependent manner.
A mean spherical approximation study of the capacitance of an electric double layer formed by a high density electrolyte
Authors: Henderson Douglas , Lamperski Stanisław , Outhwaite Christopher W. , Bhuiyan Lutful Bari
Published: March 2010

In a recent grand canonical Monte Carlo simulation and modified Poisson–Boltzmann (MPB) theoretical study of the differential capacitance of a restricted primitive model double layer at high electrolyte densities, Lamperski, Outhwaite and Bhuiyan (J. Phys. Chem. B 2009, 113, 8925) have reported a maximum in the differential capacitance as a function of electrode charge, in contrast to that seen in double layers at lower ionic densities. The venerable Gouy–Chapman–Stern (GCS) theory always yields a minimum and gives values for the capacitance that tend to be too small at these higher densities. In contrast, the mean spherical approximation (MSA) leads to better agreement with the simulation results than does the GCS approximation at higher densities but the agreement is not quite as good as for the MPB approximation. Since the MSA is a linear response theory, it gives predictions only for small electrode charge. Nonetheless, the MSA is of value since it leads to analytic results. A simple extension of the MSA to higher electrode charges would be valuable.
Mortality and cancer incidence among physicians of traditional Chinese medicine: a 20-year national follow-up study
Authors: Liu Shu-Hui , Liu Yu-Feng , Liou Saou-Hsing , Lin Yun-Lian , Hsiao Yuen-Chen , Chen Chu-Chieh , Li Chung-Yi , Wu Trong-Neng
Published: March 2010

Objective

To study the risks of mortality and cancer incidence in physicians of traditional Chinese medicine (TCM) who had frequent exposure to herbal medicine.

Methods

A population-based cohort design was conducted in which a total of 7675 certified physicians of TCM who ever practised between 1985 and 2005 were compared with the age-, sex- and calendar year-specific mortalities and cancer incidence rates of the general population of Taiwan. The age-, sex- and calendar year-standardised mortality ratio (SMR) and standardised cancer incidence ratio (SIR) were calculated to estimate the relative risks of all causes and site-specific mortality and cancer incidence.

Results

Over an up to 20-year observational period, 796 (10.4%) physicians of TCM died, and 279 (3.6%) developed cancer. The study cohort showed a significantly reduced SMR for all-causes mortality (68, 95% CI 63 to 73), and for deaths from infectious (SMR=64), circulatory (SMR=68), respiratory (SMR=64) and digestive (SMR=56) disease. The study cohort also had a significantly reduced SIR (80, 95% CI 71 to 90) for all cancers, and for neoplasm of rectum, rectosigmoid junction, and anus (SIR=45), female breast (SIR=30) and cervix uteri (SIR=10). On the other hand, we noted that physicians of TCM suffered from a significantly increased SIR for neoplasm of liver and intrahepatic bile ducts (SIR=151, 95% CI 116 to 192) and of bladder cancer (SIR=259, 95% CI 167 to 382).

Conclusion

Like other healthcare workers, we noted that physicians of TCM had significantly reduced risks of all-causes mortality and cancer incidence. Nonetheless, reasons truly responsible for significantly increased risks of liver and bladder neoplasm among physicians of TCM warrant further investigations.
INTEGRAL CONSTRAINTS ON THE MONODROMY GROUP OF THE HYPERKÄHLER RESOLUTION OF A SYMMETRIC PRODUCT OF A K3 SURFACE
Authors: MARKMAN EYAL
Published: March 2010

Let S[n]be the Hilbert scheme of length n subschemes of a K3 surface S. H2(S[n],ℤ) is endowed with the Beauville–Bogomolov bilinear form. Denote by Mon the subgroup of GL [H*(S[n],ℤ)] generated by monodromy operators, and let Mon2be its image in OH2(S[n],ℤ). We prove that Mon2is the subgroup generated by reflections with respect to +2 and -2 classes (Theorem 1.2). Thus Mon2does not surject onto OH2(S[n],ℤ)/(±1), when n - 1 is not a prime power.

As a consequence, we get counterexamples to a version of the weight 2 Torelli question for hyperKähler varieties X deformation equivalent to S[n]. The weight 2 Hodge structure on H2(X,ℤ) does not determine the bimeromorphic class of X, whenever n - 1 is not a prime power (the first case being n = 7). There are at least 2ρ(n - 1) - 1distinct bimeromorphic classes of X with a given generic weight 2 Hodge structure, where ρ(n - 1) is the Euler number of n - 1.

The second main result states, that if a monodromy operator acts as the identity on H2(S[n],ℤ), then it acts as the identity on Hk(S[n],ℤ), 0 ≤ k ≤ n + 2 (Theorem 1.5). We conclude the injectivity of the restriction homomorphism Mon → Mon2, if n ≡ 0 or n ≡ 1 modulo 4 (Corollary 1.6).
BOUNDEDNESS OF SINGULAR INTEGRALS AND MAXIMAL SINGULAR INTEGRALS ON TRIEBEL–LIZORKIN SPACES
Authors: ZHANG CHUNJIE , CHEN JIECHENG
Published: March 2010

In this paper, assuming Ω ∈ H1(Sn-1), we prove that the singular integral TΩ and the maximal singular integral [Formula: see text] are all bounded on Triebel–Lizorkin spaces, homogeneous or inhomogeneous.
STABILITY OF BOSE–EINSTEIN CONDENSATES IN A LORENTZ VIOLATING SCENARIO
Authors: CASTELLANOS E. , CAMACHO A.
Published: March 2010

We analyze the stability of a Bose–Einstein condensate in a Lorentz violating scenario, which is characterized by a deformation in the dispersion relation. The incorporation of a Lorentz violation within the bosonic statistics has, as a consequence, the emergence of a pseudo-interaction, the one can be associated to a characteristic scattering length. In addition, we calculate the relevant parameters associated to the stability of such condensate incorporating this pseudo-interaction in the nonlinear term of the Gross–Pitaevskii equation. We show that these parameters must be corrected, as a consequence of the quantum structure of spacetime.
CONFINING POTENTIAL FROM INTERACTING MAGNETIC AND TORSION FIELDS
Authors: GAETE PATRICIO , HELAŸEL-NETO JOSÉ A.
Published: March 2010

Adopting the gauge-invariant but path-dependent variables formalism, we study the coupling of torsion fields with photons in the presence of an external background electromagnetic. We explicitly show that, in the case of a constant electric field strength expectation value, the static potential remains Coulombic, while in the case of a constant magnetic field strength expectation value a confining potential is obtained. This result displays a marked qualitative departure from the usual coupling of axionlike particles with photons in the presence of an external magnetic field.
POSITIVE SOLUTIONS FOR A FOURTH-ORDER QUASILINEAR EQUATION WITH CRITICAL SOBOLEV EXPONENT
Authors: DOS SANTOS EDERSON MOREIRA
Published: March 2010

We consider a fourth-order quasilinear equation depending on a positive parameter ∊ and with critical growth. Such equation is equivalent to a critical Hamiltonian system and the main goal of this work is to prove the existence of at least two positive solutions when the parameter ∊ is sufficiently small.
ASYMPTOTIC STABLILITY, CONVEXITY, AND LIPSCHITZ REGULARITY OF DOMAINS IN THE ANISOTROPIC REGIME
Authors: VÉTOIS JÉRÔME
Published: March 2010

Anisotropic operators appear in several branches of applied sciences and, in particular, physics. They involve directional derivatives with distinct weights which create distortions in the ambient space. Anisotropic rescaling comes with the notion of asymptotically stable domains. We prove two results: one of geometric nature, the other one of analytic nature, where both guarantee that a given domain is asymptotically stable. We also discuss specific examples.
NEW L1-GRADIENT TYPE ESTIMATES OF SOLUTIONS TO ONE-DIMENSIONAL QUASILINEAR PARABOLIC SYSTEMS
Authors: ANTONTSEV S. N. , DÍAZ J. I.
Published: March 2010

We consider a general class of one-dimensional parabolic systems, mainly coupled in the diffusion term, which, in fact, can be of the degenerate type. We derive some new L1-gradient type estimates for its solutions which are uniform in the sense that they do not depend on the coefficients nor on the size of the spatial domain. We also give some applications of such estimates to gas dynamics, filtration problems, a p-Laplacian parabolic type equation and some first order systems of Hamilton–Jacobi or conservation laws type.
EMPIRICAL POTENTIALS FOR ION BINDING IN PROTEINS
Authors: RAHMANOV SERGEI , KULAKOVSKIY IVAN , UROSHLEV LEONID , MAKEEV VSEVOLOD
Published: March 2010

Empirical potentials for interaction of proteins with intracellular ions are presented. We derive the potentials using a training dataset of the protein 3D structure bank, PDB, based on the statistical analysis of contacts between ions and protein atoms of different types. The potentials are derived using Monte Carlo Reference State, simulating non-interacting structure elements as random 3D points in the structure space. The resulting potentials are detailed, continuous, and cover a wide range of contact distances. The obtained potentials were tested for prediction of ion-binding sites in proteins and are shown to reproduce locations and specificities of ion-binding sites with a high accuracy. A web server is created for predictions of ion-binding sites in proteins.
Porphyrin self-assembled monolayers and photodynamic oxidation of tryptophan
Authors: Chambrier Isabelle , Russell David A. , Brundish Derek E. , Love William G. , Jori Giulio , Magaraggia M. , Cook Michael J.
Published: March 2010

The zinc and magnesium metalated derivatives of 5,5′-[12,12′-di(thiododecyloxy)-4,4′-phenyl)]-10,10′,15,15′,20,20′-hexakis(3,3′,4,4′,5,5′-hexakisdecyloxyphenyl)diporphyrin, 1b and 1c, have been synthesised and deposited to form self-assembled monolayer (SAM) films on the surface of gold-coated glass substrates. The SAM films have been characterized by RAIR spectroscopy and fluorescence spectroscopy. The potential for the porphyrin films to catalyze the oxidation of tryptophan within human serum albumin upon irradiation with white light has been demonstrated and attributed to the porphyrins acting as photosensitizers of oxygen to form oxidizing species.
Inter-ring interactions in [Fe(TalkylP)(Cl)] (alkyl = ethyl, n-propyl, n-hexyl) complexes: control bymeso-substituted groups
Authors: Li Ming , Neal Teresa J. , Ehlinger Noelle , Schulz Charles E. , Scheidt W. Robert
Published: March 2010

Syntheses, molecular structures and magnetic susceptibilities of three meso-substituted high-spin iron(III) porphyrinate complexes ([ Fe(TEtP)(Cl) ], [ Fe(TPrP)(Cl) ], and [ Fe(THexP)(Cl) ]) are described. It was determined that the inter-ring interactions within each dimeric unit change upon alteration of the alkyl groups at the meso positions. Magnetic exchange couplings between iron centers of the dimers are in accord with the trends in structural inter-ring geometries. Crystal data for [ Fe(TEtP)(Cl) ]: a = 10.1710(5) Å, b = 11.309(3) Å, c = 12.170(3) Å, α = 91.774(9)°, β = 113.170(14)°, γ = 112.149(9)°, V = 1165.2(4) Å3, triclinic, [Formula: see text], Z = 2, R1= 0.0844 and wR2= 0.2073 for observed data. Crystal data for [ Fe(TPrP)(Cl) ]: a = 13.040(2) Å, b = 15.221(2) Å, c = 14.6681(9) Å, β = 109.997(11)°, V = 2735.9(7) Å3, monoclinic, P21/ n , Z = 4, R1= 0.0477 and wR2= 0.1176 for observed data. Crystal data for [ Fe(THexP)(Cl) ]: a = 10.246(7) Å, b = 12.834(4) Å, c = 17.420(15) Å, α = 69.74(3)°, β = 87.52(4)°, γ = 84.89(3)°, V = 2140(2) Å3, triclinic, [Formula: see text], Z = 2, R1= 0.1024 and wR2= 0.2659 for observed data.
Synthesis and self-assembly of a novel cobalt(II) porphyrin lipoic acid derivative on gold
Authors: Eberle Christoph S. , Viana Ana S. , Montforts Franz-Peter , Abrantes Luisa Maria
Published: March 2010

A novel Co(II) porphyrin lipoic acid derivative was synthesized starting from the commerically available red blood pigment hemin. The disulfide functionalities of the lipoic acid moieties allowed its immobilization on gold by a self-assembly method. The Co(II) porphyrin self-assembled monolayer (SAMs) on gold (111) surfaces were characterized electrochemically through monolayer reductive desorption and evaluation of the redox properties of the immobilized molecules in organic medium, and by scanning tunneling microscopy (STM). It was found that after assembly the Co(II) porphyrin is electroactive exhibiting the typical redox processes observed for its precursor without the appended lipoic acid in solution. A coverage of 2.7 × 10-10 mol.cm -2 has been estimated assuming that four electrons (one per each sulfur atom) are involved in the process. The porphyrin-modified gold electrodes exhibit catalytic acitivity demonstrated towards the reduction of molecular oxygen in acidic solution.
Synthesis, characterization and electrochemistry of the novel metalloporphyrazines annulated with tetrathiafulvalene having pentoxycarbonyl substituents
Authors: Leng Fengshou , Hou Ruibin , Jin Longyi , Yin Bingzhu , Xiong Ren-Gen
Published: March 2010

Three novel tetrathiafulvalene-annulated metalloporphyrazines with electron-withdrawing pentoxycarbonyl groups at the periphery were synthesized via the cyclotetramerization of dipentyl 6,7-dicyanotetrathiafulvalen-2,3-dicarboxylate in the presence of corresponding metal salts ( Zn(OAc)2·2H2O , Cu(OAc)2·2H2O , and NiCl2 ) and in pentanol. Molecular structures were fully characterized by 1H NMR, FT-IR, UV-vis, MALDI-TOF mass spectra and elemental analysis. These newly synthesized macrocyclic dyes were sufficiently stable in air during the purification process and also in further experiments. Electron-withdrawing substituents reduced the ability of tetrathiafulvalene groups to form radical cations. Solution electrochemical data showed one reductive and three oxidative processes within a -2000 mV to +2200 mV potential window. The four couples observed were assigned to Pz -2/ Pz -3 (I), TTF +•/ TTF (II), TTF +2/ TTF +• (III) and Pz -1/ Pz -2 (IV).
Regulated transport of sulfate and oxalate by SLC26A2/DTDST
Authors: Heneghan John F. , Akhavein Arash , Salas Maria J. , Shmukler Boris E. , Karniski Lawrence P. , Vandorpe David H. , Alper Seth L.
Published: March 2010

Nephrolithiasis in the Slc26a6−/− mouse is accompanied by 50–75% reduction in intestinal oxalate secretion with unchanged intestinal oxalate absorption. The molecular identities of enterocyte pathways for oxalate absorption and for Slc26a6-independent oxalate secretion remain undefined. The reported intestinal expression of SO42− transporter SLC26A2 prompted us to characterize transport of oxalate and other anions by human SLC26A2 and mouse Slc26a2 expressed in Xenopus oocytes. We found that hSLC26A2-mediated [14C]oxalate uptake ( K1/2 of 0.65 ± 0.08 mM) was cis-inhibited by external SO42− ( K1/2 of 3.1 mM). hSLC26A2-mediated bidirectional oxalate/SO42− exchange exhibited extracellular SO42− K1/2 of 1.58 ± 0.44 mM for exchange with intracellular [14C]oxalate, and extracellular oxalate K1/2 of 0.14 ± 0.11 mM for exchange with intracellular 35SO42−. Influx rates and K1/2 values for mSlc26a2 were similar. hSLC26A2-mediated oxalate/Cl− exchange and bidirectional SO42−/Cl− exchange were not detectably electrogenic. Both SLC26A2 orthologs exhibited nonsaturable extracellular Cl− dependence for efflux of intracellular [14C]oxalate, 35SO42−, or 36Cl−. Rate constants for 36Cl− efflux into extracellular Cl−, SO42−, and oxalate were uniformly 10-fold lower than for oppositely directed exchange. Acidic extracellular pH (pHo) inhibited all modes of hSLC26A2-mediated anion exchange. In contrast, acidic intracellular pH (pHi) selectively activated exchange of extracellular Cl− for intracellular 35SO42− but not for intracellular 36Cl− or [14C]oxalate. Protein kinase C inhibited hSLC26A2 by reducing its surface abundance. Diastrophic dysplasia mutants R279W and A386V of hSLC26A2 exhibited similar reductions in uptake of both 35SO42− and [14C]oxalate. A386V surface abundance was reduced, but R279W surface abundance was at wild-type levels.
Osmoregulation of ceroid neuronal lipofuscinosis type 3 in the renal medulla
Authors: Stein Colleen S. , Yancey Paul H. , Martins Inês , Sigmund Rita D. , Stokes John B. , Davidson Beverly L.
Published: March 2010

Recessive inheritance of mutations in ceroid neuronal lipofuscinosis type 3 ( CLN3) results in juvenile neuronal ceroid lipofuscinosis (JNCL), a childhood neurodegenerative disease with symptoms including loss of vision, seizures, and motor and mental decline. CLN3p is a transmembrane protein with undefined function. Using a Cln3 reporter mouse harboring a nuclear-localized bacterial β-galactosidase (β-Gal) gene driven by the native Cln3 promoter, we detected β-Gal most prominently in epithelial cells of skin, colon, lung, and kidney. In the kidney, β-Gal-positive nuclei were predominant in medullary collecting duct principal cells, with increased expression along the medullary osmotic gradient. Quantification of Cln3 transcript levels from kidneys of wild-type ( Cln3+/+) mice corroborated this expression gradient. Reporter mouse-derived renal epithelial cultures demonstrated a tonicity-dependent increase in β-Gal expression. RT-quantitative PCR determination of Cln3 transcript levels further supported osmoregulation at the Cln3 locus. In vivo, osmoresponsiveness of Cln3 was demonstrated by reduction of medullary Cln3 transcript abundance after furosemide administration. Primary cultures of epithelial cells of the inner medulla from Cln3lacZ/lacZ (CLN3p-null) mice showed no defect in osmolyte accumulation or taurine flux, arguing against a requirement for CLN3p in osmolyte import or synthesis. CLN3p-deficient mice with free access to water showed a mild urine-concentrating defect but, upon water deprivation, were able to concentrate their urine normally. Unexpectedly, we found that CLN3p-deficient mice were hyperkalemic and had a low fractional excretion of K+. Together, these findings suggest an osmoregulated role for CLN3p in renal control of water and K+ balance.
Amino acid sensing by enteroendocrine STC-1 cells: role of the Na+-coupled neutral amino acid transporter 2
Authors: Young Steven H. , Rey Osvaldo , Sternini Catia , Rozengurt Enrique
Published: March 2010

The results presented here show that STC-1 cells, a model of intestinal endocrine cells, respond to a broad range of amino acids, including l-proline, l-serine, l-alanine, l-methionine, l-glycine, l-histidine, and α-methyl-amino-isobutyric acid (MeAIB) with a rapid increase in the intracellular Ca2+ concentration ([Ca2+]i). We sought to identify the mechanism by which amino acids induce Ca2+ signaling in these cells. Several lines of evidence suggest that amino acid transport through the Na+-coupled neutral amino acid transporter 2 (SNAT2) is a major mechanism by which amino acids induced Ca2+ signaling in STC-1 cells: 1) the amino acid efficacy profile for inducing Ca2+ signaling in STC-1 cells closely matches the amino acid specificity of SNAT2; 2) amino acid-induced Ca2+ signaling in STC-1 cells was suppressed by removing Na+ from the medium; 3) the nonmetabolized synthetic substrate of amino acid transport MeAIB produced a marked increase in [Ca2+]i; 4) transfection of small interfering RNA targeting SNAT2 produced a marked decrease in Ca2+ signaling in response to l-proline in STC-1 cells; 5) amino acid-induced increase in [Ca2+]i was associated with membrane depolarization and mediated by Ca2+ influx, since it depended on extracellular Ca2+; 6) the increase in [Ca2+]i in response to l-proline, l-alanine, or MeAIB was abrogated by either nifedipine (1–10 μM) or nitrendipine (1 μM), which block L-type voltage-sensitive Ca2+ channels. We hypothesize that the inward current of Na+ associated with the function of SNAT2 leads to membrane depolarization and activation of voltage-sensitive Ca2+ channels that mediate Ca2+ influx, thereby leading to an increase in the [Ca2+]i in enteroendocrine STC-1 cells.
Targeted ablation of mesenteric projecting sympathetic neurons reduces the hemodynamic response to pain in conscious, spinal cord-transected rats
Authors: Lujan Heidi L. , Palani Gurunanthan , Peduzzi Jean D. , DiCarlo Stephen E.
Published: March 2010

Individuals with spinal cord injuries above thoracic level 6 (T6) experience episodic bouts of life-threatening hypertension as part of a condition termed autonomic dysreflexia. The paroxysmal hypertension can be caused by a painful stimulus below the level of the injury. Targeted ablation of mesenteric projecting sympathetic neurons may reduce the severity of autonomic dysreflexia by reducing sympathetic activity. Therefore, cholera toxin B subunit (CTB) conjugated to saporin (SAP; a ribosomal inactivating protein that binds to and inactivates ribosomes) was injected into the celiac ganglion to test the hypothesis that targeted ablation of mesenteric projecting sympathetic neurons reduces the pressor response to pain in conscious, spinal cord-transected rats. Nine Sprague-Dawley male rats underwent a spinal cord transection between thoracic vertebrae 4 and 5. Following recovery (5 wk), all rats were instrumented with a radio telemetry device for recording arterial pressure and bilateral catheters in the gluteus maximus muscles for the infusion of hypertonic saline (hNa+Cl−). Subsequently, the hemodynamic responses to intramuscular injection of hNa+Cl− (100 μl and 250 μl, in random order) were determined. Following the experiments in the no celiac ganglia injected condition (NGI), rats received injections of CTB-SAP ( n = 5) or CTB ( n = 3) into the celiac ganglia. CTB-SAP rats, compared with NGI and CTB rats, had reduced pressor responses to hNa+Cl−. Furthermore, the number of stained neurons in the celiac ganglia and spinal cord (segments T6–T12), was reduced in CTB-SAP rats. Thus, CTB-SAP retrogradely transported from the celiac ganglia is effective at ablating mesenteric projecting sympathetic neurons and reducing the pressor response to pain in spinal cord-transected rats.
Regulated oxygen sensing by protein hydroxylation in renal erythropoietin-producing cells
Authors: Wenger Roland H. , Hoogewijs David
Published: March 2010

The kidney is a major site of systemic oxygen sensing, regulating blood erythrocyte and hence oxygen content by hypoxia-inducible erythropoietin (Epo) expression. A constant ratio between blood perfusion and oxygen consumption, a stable corticomedullary oxygen gradient, and a relatively low tissue Po2are the prerequisites for the function of renal Epo-producing and oxygen-sensing (REPOS) cells, which are located in the juxtamedullary cortex. In kidney disease, renal oxygen consumption is decreased, leading to an increase in Po2, dysfunction of REPOS cells, and anemia. The molecular principles of cellular oxygen sensing have been elucidated in the last few years, and genetically altered mouse models as well as hereditary diseases causing erythrocytosis have clarified the oxygen-signaling cascade leading to increased Epo expression in REPOS cells. However, the consequences of a number of recently discovered factors for the regulation of oxygen signaling in REPOS cells are unclear, asking for novel cell culture models which might be hampered by the putative neuron-like nature of this enigmatic cell type.
Modification of angiogenic factors by regular and acute exercise during pregnancy
Authors: Weissgerber Tracey L. , Davies Gregory A. L. , Roberts James M.
Published: March 2010

This cross-sectional study examined mechanisms through which exercise might alter preeclampsia risk by estimating the effects of acute and chronic exercise on angiogenic markers in healthy pregnant women with different amounts of regular exercise participation. Serum-soluble fms-like tyrosine kinase-1 (sFlt-1), placental growth factor (PlGF), and soluble endoglin (sEng) were measured before and after 20 min of moderate-intensity cycle ergometry in normotensive, nonsmoking pregnant (16 active, 9 inactive, 34.1 ± 1.6 wk gestation) and nonpregnant (15 active, 12 inactive, midlate luteal phase) women. Inactive women did not regularly exercise at an intensity that was sufficient to cause sweating. Active women exercised for at least 3 h/wk. Inactive pregnant women had significantly lower PlGF concentrations [median (interquartile range): 268 (159, 290) vs. 278 (221, 647) pg/ml, P = 0.014] and higher sFlt-1 [5,180 (4,540, 5,834) vs. 4,217 (2,014, 5,481) pg/ml, P = 0.005] and sEng concentrations [9.1 (7.7, 16.7) vs. 7.8 (6.5, 10.1) ng/ml, P = 0.025] than active pregnant women. This effect of regular exercise participation was not observed in nonpregnant women. Acute exercise in pregnancy was not associated with antiangiogenic changes that might contribute to preeclampsia; rather, there was a small, but statistically significant, increase in PlGF following acute exercise in active pregnant women [278 (221, 647) vs. 335 (245, 628) pg/ml, P = 0.014]. sFlt-1 increased significantly following acute exercise in inactive nonpregnant women [90 (86, 100) vs. 106 (101, 116) pg/ml, P = 0.012], but not in active nonpregnant women. Regular exercise during pregnancy is associated with higher serum PlGF and lower sFlt-1 and sEng concentrations in late gestation, a difference that is unlikely to have predated the pregnancy.
A prior bout of contractions speeds V̇o2 and blood flow on-kinetics and reduces the V̇o2 slow-component amplitude in canine skeletal muscle contracting in situ
Authors: Hernández Andrés , McDonald James R. , Lai Nicola , Gladden L. Bruce
Published: March 2010

It was the purpose of this study to examine the effect of a priming contractile bout on oxygen uptake (V̇o2) on-kinetics in highly oxidative skeletal muscle. Canine gastrocnemii ( n = 12) were stimulated via their sciatic nerves (8 V, 0.2-ms duration, 50 Hz, 200-ms train) at a rate of 2 contractions/3 s (≈70% peak V̇o2) for two 2-min bouts, separated by 2 min of recovery. Blood flow was recorded with an ultrasonic flowmeter, and muscle oxygenation monitored via near-infrared spectroscopy. Compared with the first bout ( bout 2 vs. bout 1), the V̇o2 primary time constant (mean ± SD, 9.4 ± 2.3 vs. 12.0 ± 3.9 s) and slow-component amplitude (5.9 ± 6.3 vs. 12.1 ± 9.0 ml O2·kg wet wt−1·min−1) were significantly reduced ( P < 0.05) during the second bout. Blood flow on-kinetics were significantly speeded during the second bout (time constant = 7.7 ± 2.6 vs. 14.8 ± 5.8 s), and O2 extraction was greater at the onset of contractions (0.050 ± 0.030 vs. 0.020 ± 0.010 ml O2/ml blood). Kinetics of muscle deoxygenation were significantly slower at the onset of the second bout (7.2 ± 2.2 vs. 4.4 ± 1.2 s), while relative oxyhemoglobin concentration was elevated throughout the second bout. These results suggest that better matching of O2 delivery to V̇o2 speeds V̇o2 on-kinetics at this metabolic rate, but do not eliminate a potential role for enhanced metabolic activation. Additionally, altered motor unit recruitment at the onset of a second bout is not a prerequisite for reductions in the V̇o2 slow-component amplitude after a priming contractile bout in canine muscle in situ.
Impaired Glial Glutamate Uptake Induces Extrasynaptic Glutamate Spillover in the Spinal Sensory Synapses of Neuropathic Rats
Authors: Nie Hui , Weng Han-Rong
Published: March 2010

Glial cell dysfunction and excessive glutamate receptor activation in spinal dorsal horn neurons are hallmark mechanisms of pathological pain. The way in which glial cell dysfunction leads to excessive glutamate receptor activation in the spinal sensory synapses remains unknown. We and others recently reported the downregulation of glial glutamate transporter (GT) protein expression in the spinal dorsal horn of neuropathic rats. In this study, we showed that excitatory postsynaptic currents originating from N-methyl-d-aspartate receptor activation (NMDA EPSCs) elicited by peripheral synaptic input in the spinal sensory synapses were enhanced in neuropathic rats with mechanical allodynia induced by partial sciatic nerve ligation. The enhanced NMDA EPSCs were accompanied by an increased proportion of NR2B receptor activation. Physically blocking the extrasynaptic glutamate with dextran or chemically scavenging the glutamate with glutamic-pyruvic transaminase ameliorated the abnormal NMDA EPSCs in neuropathic rats. Pharmacological blockade of glial GTs with dihydrokainic acid enhanced NMDA receptor activation elicited by synaptic input or puffed glutamate in normal control rats, but this effect was precluded in neuropathic rats. Thus extrasynaptic glutamate spillover and extrasynaptic NMDA receptor activation induced by deficient glial glutamate uptake in the synapses resulted in the excessive activation of NMDA receptors in neuropathic rats. It is suggested that extrasynaptic glutamate spillover may be a key synaptic mechanism related to phenotypic alterations induced by nerve injury in the spinal dorsal horn and that glial GTs are potential new targets in the development of analgesics.
Release and Elementary Mechanisms of Nitric Oxide in Hair Cells
Authors: Lv Ping , Rodriguez-Contreras Adrian , Kim Hyo Jeong , Zhu Jun , Wei Dongguang , Choong-Ryoul Sihn , Eastwood Emily , Mu Karen , Levic Snezana , Song Haitao , Yevgeniy Petrov Y. , Smith Peter J. S. , Yamoah Ebenezer N.
Published: March 2010

The enzyme nitric oxide (NO) synthase, that produces the signaling molecule NO, has been identified in several cell types in the inner ear. However, it is unclear whether a measurable quantity of NO is released in the inner ear to confer specific functions. Indeed, the functional significance of NO and the elementary cellular mechanism thereof are most uncertain. Here, we demonstrate that the sensory epithelia of the frog saccule release NO and explore its release mechanisms by using self-referencing NO-selective electrodes. Additionally, we investigated the functional effects of NO on electrical properties of hair cells and determined their underlying cellular mechanism. We show detectable amounts of NO are released by hair cells (>50 nM). Furthermore, a hair-cell efferent modulator acetylcholine produces at least a threefold increase in NO release. NO not only attenuated the baseline membrane oscillations but it also increased the magnitude of current required to generate the characteristic membrane potential oscillations. This resulted in a rightward shift in the frequency–current relationship and altered the excitability of hair cells. Our data suggest that these effects ensue because NO reduces whole cell Ca2+current and drastically decreases the open probability of single-channel events of the L-type and non L-type Ca2+channels in hair cells, an effect that is mediated through direct nitrosylation of the channel and activation of protein kinase G. Finally, NO increases the magnitude of Ca2+-activated K+currents via direct NO nitrosylation. We conclude that NO-mediated inhibition serves as a component of efferent nerve modulation of hair cells.
Tonotopic Tuning in a Sound Localization Circuit
Authors: Slee Sean J. , Higgs Matthew H. , Fairhall Adrienne L. , Spain William J.
Published: March 2010

Nucleus laminaris (NL) neurons encode interaural time difference (ITD), the cue used to localize low-frequency sounds. A physiologically based model of NL input suggests that ITD information is contained in narrow frequency bands around harmonics of the sound frequency. This suggested a theory, which predicts that, for each tone frequency, there is an optimal time course for synaptic inputs to NL that will elicit the largest modulation of NL firing rate as a function of ITD. The theory also suggested that neurons in different tonotopic regions of NL require specialized tuning to take advantage of the input gradient. Tonotopic tuning in NL was investigated in brain slices by separating the nucleus into three regions based on its anatomical tonotopic map. Patch-clamp recordings in each region were used to measure both the synaptic and the intrinsic electrical properties. The data revealed a tonotopic gradient of synaptic time course that closely matched the theoretical predictions. We also found postsynaptic band-pass filtering. Analysis of the combined synaptic and postsynaptic filters revealed a frequency-dependent gradient of gain for the transformation of tone amplitude to NL firing rate modulation. Models constructed from the experimental data for each tonotopic region demonstrate that the tonotopic tuning measured in NL can improve ITD encoding across sound frequencies.
Brief Sounds Evoke Prolonged Responses in Anesthetized Ferret Auditory Cortex
Authors: Campbell Robert A. A. , Schulz Andreas L. , King Andrew J. , Schnupp Jan W. H.
Published: March 2010

Neurons in the auditory cortex of anesthetized animals are generally considered to generate phasic responses to simple stimuli such as tones or noise bursts. In this paper, we show that under ketamine/medetomidine anesthesia, neurons in ferret auditory cortex usually exhibit complex sustained responses. We presented 100-ms broad-band noise bursts at a range of interaural level differences (ILDs) and average binaural levels (ABLs), and used extracellular electrodes to monitor evoked activity over 700 ms poststimulus onset. We estimated the degree of randomness (noise) in the response functions of individual neurons over poststimulus time; we found that neural activity was significantly modulated by sound for up to ∼500 ms following stimulus offset. Pooling data from all neurons, we found that spiking activity carries significant information about stimulus identity over this same time period. However, information about ILD decayed much more quickly over time compared with information about ABL. In addition, ILD and ABL are coded independently by the neural population even though this is not the case at individual neurons. Though most neurons responded more strongly to ILDs corresponding to the opposite side of space, as a population, they were equally informative about both contra- and ipsilateral stimuli.
Independent Epileptiform Discharge Patterns in the Olfactory and Limbic Areas of the In Vitro Isolated Guinea Pig Brain During 4-Aminopyridine Treatment
Authors: Carriero Giovanni , Uva Laura , Gnatkovsky Vadym , Avoli Massimo , de Curtis Marco
Published: March 2010

In vitro studies performed on brain slices demonstrate that the potassium channel blocker 4-aminopyridine (4AP, 50 μM) discloses electrographic seizure activity and interictal discharges. These epileptiform patterns have been further analyzed here in a isolated whole guinea pig brain in vitro by using field potential recordings in olfactory and limbic structures. In 8 of 13 experiments runs of fast oscillatory activity ( fast runs, FRs) in the piriform cortex (PC) propagated to the lateral entorhinal cortex (EC), hippocampus and occasionally to the medial EC. Early and late FRs were asynchronous in the hemispheres showed different duration [1.78 ± 0.51 and 27.95 ± 4.55 (SD) s, respectively], frequency of occurrence (1.82 ± 0.49 and 34.16 ± 6.03 s) and frequency content (20–40 vs. 40–60 Hz). Preictal spikes independent from the FRs appeared in the hippocampus/EC and developed into ictal-like discharges that did not propagate to the PC. Ictal-like activity consisted of fast activity with onset either in the hippocampus ( n = 6) or in the mEC ( n = 2), followed by irregular spiking and sequences of diffusely synchronous bursts. Perfusion of the N-methyl-d-aspartate receptor antagonist 2-amino-5-phosphonopentanoic acid (100 μM) did not prevent FRs, increased the duration of limbic ictal-like discharges and favored their propagation to olfactory structures. The AMPA receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (50 μM) blocked ictal-like events and reduced FRs. In conclusion, 4AP-induced epileptiform activities are asynchronous and independent in olfactory and hippocampal-entorhinal regions. Epileptiform discharges in the isolated guinea pig brain show different pharmacological properties compared with rodent in vitro slices.