bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of a Standardized Bovine Serum Panel To Evaluate a Multiplexed Nonstructural Protein Antibody Assay for Serological Surveillance of Foot-and-Mouth Disease
Authors: Perkins Julie , Parida Satya , Clavijo Alfonso
Published: October 2007

Liquid array technology has previously been used to show proof of principle of a multiplexed nonstructural protein serological assay to differentiate foot-and-mouth disease virus-infected and vaccinated animals. The current multiplexed assay consists of synthetically produced peptide signatures 3A, 3B, and 3D and the recombinant protein signature 3ABC in combination with four controls. To determine the diagnostic specificity of each signature in the multiplex, the assay was evaluated against a naive population (
n
= 104) and a vaccinated population (
n
= 94). Subsequently, the multiplexed assay was assessed by using a panel of bovine sera generated by the World Reference Laboratory for foot-and-mouth disease in Pirbright, United Kingdom. This serum panel has been used to assess the performance of other singleplex enzyme-linked immunosorbent assay (ELISA)-based nonstructural protein antibody assays. The 3ABC signature in the multiplexed assay showed performance comparable to that of a commercially available nonstructural protein 3ABC ELISA (Cedi test), and additional information pertaining to the relative diagnostic sensitivity of each signature in the multiplex was acquired in one experiment. The encouraging results of the evaluation of the multiplexed assay against a panel of diagnostically relevant samples promote further assay development and optimization to generate an assay for routine use in foot-and-mouth disease serological surveillance.
Development of a Rapid and Convenient Method for Determination of Rubella Virus-Specific Immunoglobulin G Avidity
Authors: Vauloup-Fellous Christelle , Ursulet-Diser Jessica , Grangeot-Keros Liliane
Published: October 2007

We describe here a rapid and semiautomated method for the determination of rubella virus immunoglobulin G (IgG) avidity with the VIDAS instrument. A total of 153 serum samples from persons with naturally acquired rubella virus infections (
n
= 98), from vaccinated persons (
n
= 44), and from patients with autoantibodies (
n
= 11) were included in this study. The rubella virus-specific IgG avidity assay we developed for the VIDAS instrument was evaluated by comparison with an in-house method. Results obtained with the VIDAS instrument allow considering this method valuable to help confirm or exclude acute primary infection or recent vaccination.
Suture-Related Keratitis Caused by
Corynebacterium macginleyi
Authors: Suzuki Takashi , Iihara Hirotoshi , Uno Toshihiko , Hara Yuko , Ohkusu Kiyofumi , Hata Hiroyuki , Shudo Masachika , Ohashi Yuichi
Published: October 2007

We report two cases of suture-related keratitis following penetrating keratoplasty. In both cases,
Corynebacterium macginleyi
was isolated from corneal specimens. Scanning electron microscopy revealed that corynebacteria could aggregate and form a biofilm. The MICs of sulbenicillin and fluoroquinolones were high for both isolates. Our findings show that
C. macginleyi
can cause keratitis with biofilm formation.
Rapid, Standardized Method for Determination of
Mycobacterium tuberculosis
Drug Susceptibility by Use of Mycolic Acid Analysis
Authors: Parrish Nicole , Osterhout Gerard , Dionne Kim , Sweeney Amy , Kwiatkowski Nicole , Carroll Karen , Jost Kenneth C. , Dick James
Published: October 2007

Multidrug-resistant (MDR)
Mycobacterium tuberculosis
and extrensively drug-resistant (XDR)
M. tuberculosis
are emerging public health threats whose threats are compounded by the fact that current techniques for testing the susceptibility of
M. tuberculosis
require several days to weeks to complete. We investigated the use of high-performance liquid chromatography (HPLC)-based quantitation of mycolic acids as a means of rapidly determining drug resistance and susceptibility in
M. tuberculosis
. Standard susceptibility testing and determination of the MICs of drug-susceptible (
n
= 26) and drug-resistant
M. tuberculosis
strains, including MDR
M. tuberculosis
strains (
n
= 34), were performed by using the Bactec radiometric growth system as the reference method. The HPLC-based susceptibilities of the current first-line drugs, isoniazid (INH), rifampin (RIF), ethambutol (EMB), and pyrazinamide (PZA), were determined. The vials were incubated for 72 h, and aliquots were removed for HPLC analysis by using the Sherlock mycobacterial identification system. HPLC quantitation of total mycolic acid peaks (TMAPs) was performed with treated and untreated cultures. At 72 h, the levels of agreement of the HPLC method with the reference method were 99.5% for INH, EMB, and PZA and 98.7% for RIF. The inter- and intra-assay reproducibilities varied by drug, with an average precision of 13.4%. In summary, quantitation of TMAPs is a rapid, sensitive, and accurate method for antibiotic susceptibility testing of all first-line drugs currently used against
M. tuberculosis
and offers the potential of providing susceptibility testing results within hours, rather than days or weeks, for clinical
M. tuberculosis
isolates.
Promoter- and Cell-Specific Transcriptional Transactivation by the Kaposi's Sarcoma-Associated Herpesvirus ORF57/Mta Protein
Authors: Palmeri Diana , Spadavecchia Sophia , Carroll Kyla Driscoll , Lukac David M.
Published: October 2007

The Kaposi's sarcoma-associated herpesvirus (KSHV) Mta protein, encoded by open reading frame 57, is a transactivator of gene expression that is essential for productive viral replication. Previous studies have suggested both transcriptional and posttranscriptional roles for Mta, but little is known regarding Mta's transcriptional function. In this study, we demonstrate that Mta cooperates with the KSHV lytic switch protein, Rta, to reactivate KSHV from latency, but Mta has little effect on reactivation when expressed alone. We demonstrate that the Mta and Rta proteins are expressed with similar but distinct kinetics during KSHV reactivation. In single-cell analyses, Mta expression coincides tightly with progression to full viral reactivation. We demonstrate with promoter reporter assays that while Rta activates transcription in all cell lines tested, Mta's ability to transactivate promoters, either alone or synergistically with Rta, is cell and promoter specific. In particular, Mta robustly transactivates the nut-1/PAN promoter independently of Rta in 293 and Akata-31 cells. Using nuclear run-on assays, we demonstrate that Mta stimulates transcriptional initiation in 293 cells. Rta and Mta physically interact in infected cell extracts, and this interaction requires the intact leucine repeat and central region of Rta in vitro. We demonstrate that Mta also binds to the nut-1/PAN promoter DNA in vitro and in infected cells. An Mta mutant with a lesion in a putative A/T hook domain is altered in DNA binding and debilitated in transactivation. We propose that one molecular mechanism of Mta-mediated transactivation is a direct effect on transcription by direct and indirect promoter association.
Overexpression of the Kaposi's Sarcoma-Associated Herpesvirus Transactivator K-Rta Can Complement a K-bZIP Deletion BACmid and Yields an Enhanced Growth Phenotype
Authors: Kato-Noah Taeko , Xu Yiyang , Rossetto Cyprian C. , Colletti Kelly , Papousková Iva , Pari Gregory S.
Published: October 2007

Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8 (HHV8) ORF50 encodes a transactivator, K-Rta, which functions as the switch from latent to lytic virus replication. K-bZIP interacts with K-Rta and can repress its transactivation activity for some viral promoters. Both K-Rta and K-bZIP are required for origin-dependent DNA replication. To determine the role of K-bZIP in the context of the viral genome, we generated a recombinant HHV8 bacterial artificial chromosome (BAC) with a deletion in the K-bZIP open reading frame. This BACmid, BAC36ΔK8, displayed an enhanced growth phenotype with respect to virus production and accumulation of virus-encoded mRNAs measured by real-time PCR when K-Rta was used to induce the virus lytic cycle. Conversely, induction of the virus lytic cycle using tetradecanoyl phorbol acetate/
n
-butyrate resulted in no virus production and an aberrant gene expression pattern from BAC36ΔK8-containing cells compared to wild-type (wt) BAC. This null virus phenotype was efficiently complemented by the expression of K-bZIP in
trans
, restoring virus production to wt BAC levels. Immunofluorescence staining revealed that subcellular localization of K-Rta was unchanged; however, a disruption of LANA subcellular localization was observed in cells harboring BAC36ΔK8, suggesting that K-bZIP influences LANA localization. Coimmunoprecipitation experiments confirmed that K-bZIP interacts with LANA in BCBL-1 cells and in cotransfection assays. Lastly, the chromatin immunoprecipitation assay revealed that, in an environment where K-Rta is overexpressed and in the absence of K-bZIP, K-Rta binds to CAAT enhancer binding protein α sites within oriLyt, suggesting that it is K-Rta that supplies an essential replication function and that K-bZIP may serve to augment or facilitate the interaction of K-Rta with oriLyt.
Dendritic Cells Are Less Susceptible to Human Immunodeficiency Virus Type 2 (HIV-2) Infection than to HIV-1 Infection
Authors: Duvall Melody G. , Loré Karin , Blaak Hetty , Ambrozak David A. , Adams William C. , Santos Kathlyn , Geldmacher Christof , Mascola John R. , McMichael Andrew J. , Jaye Assan , Whittle Hilton C. , Rowland-Jones Sarah L. , Koup Richard A.
Published: October 2007

Human immunodeficiency virus type 1 (HIV-1) infection of dendritic cells (DCs) has been documented in vivo and may be an important contributor to HIV-1 transmission and pathogenesis. HIV-1-specific CD4+T cells respond to HIV antigens presented by HIV-1-infected DCs and in this process become infected, thereby providing a mechanism through which HIV-1-specific CD4+T cells could become preferentially infected in vivo. HIV-2 disease is attenuated with respect to HIV-1 disease, and host immune responses are thought to be contributory. Here we investigated the susceptibility of primary myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) to infection by HIV-2. We found that neither CCR5-tropic primary HIV-2 isolates nor a lab-adapted CXCR4-tropic HIV-2 strain could efficiently infect mDCs or pDCs, though these viruses could infect primary CD4+T cells in vitro. HIV-2-exposed mDCs were also incapable of transferring virus to autologous CD4+T cells. Despite this, we found that HIV-2-specific CD4+T cells contained more viral DNA than memory CD4+T cells of other specificities in vivo. These data suggest that either infection of DCs is not an important contributor to infection of HIV-2-specific CD4+T cells in vivo or that infection of DCs by HIV-2 occurs at a level that is undetectable in vitro. The frequent carriage of HIV-2 DNA within HIV-2-specific CD4+T cells, however, does not appear to be incompatible with preserved numbers and functionality of HIV-2-specific CD4+T cells in vivo, suggesting that additional mechanisms contribute to maintenance of HIV-2-specific CD4+T-cell help in vivo.
Intracellular Processing, Glycosylation, and Cell Surface Expression of Human Metapneumovirus Attachment Glycoprotein
Authors: Liu Li , Bastien Nathalie , Li Yan
Published: October 2007

The biosynthesis and posttranslational processing of human metapneumovirus attachment G glycoprotein were investigated. After pulse-labeling, the G protein accumulated as three species with molecular weights of 45,000, 50,000, and 53,000 (45K, 50K, and 53K, respectively).
N
-Glycosidase digestion indicated that these forms represent the unglycosylated precursor and N-glycosylated intermediate products, respectively. After an appropriate chase, these three naive forms were further processed to a mature 97K form. The presence of O-linked sugars in mature G protein was confirmed by
O
-glycanase digestion and lectin-binding assay using
Arachis hypogaea
(peanut agglutinin), an O-glycan-specific lectin. In addition, in the O-glycosylation-deficient cell line (CHO ldlD cell), the G protein could not be processed to the mature form unless the exogenous Gal and GalNAc were supplemented, which provided added evidence supporting the O-linked glycosylation of G protein. The maturation of G was completely blocked by monensin but was partially sensitive to brefeldin A (BFA), suggesting the O-linked glycosylation of G initiated in the trans-Golgi compartment and terminated in the trans-Golgi network. Enzymatic deglycosylation analysis confirmed that the BFA-G was a partial mature form containing N-linked oligosaccharides and various amounts of O-linked carbohydrate side chains. The expression of G protein at the cell surface could be detected by indirect immunofluorescence staining assay. Furthermore, cell surface immunoprecipitation displayed an efficient intracellular transport of G protein.
RNA Binding Domain of Jamestown Canyon Virus S Segment RNAs
Authors: Ogg Monica M. , Patterson Jean L.
Published: October 2007

Jamestown Canyon virus (JCV) is a member of the
Bunyaviridae
family,
Orthobunyavirus
genus, California serogroup. Replication and, ultimately, assembly and packaging rely on the process of encapsidation. Therefore, the ability of viral RNAs (vRNAs) (genomic and antigenomic) to interact with the nucleocapsid protein (N protein) and the location of this binding domain on the RNAs are of interest. The questions to be addressed are the following. Where is the binding domain located on both the vRNA and cRNA strands, is this RNA bound when double or single stranded, and does this identified region have the ability to transform the binding potential of nonviral RNA? Full-length viral and complementary S segment RNA, as well as 3′ deletion mutants of both vRNA and cRNA, nonviral RNA, and hybrid viral/nonviral RNA, were analyzed for their ability to interact with bacterially expressed JCV N protein. RNA-nucleocapsid interactions were examined by UV cross-linking, filter binding assays, and the generation of hybrid RNA to help define the area responsible for RNA-protein binding. The assays identified the region responsible for binding to the nucleocapsid as being contained within the 5′ half of both the genomic and antigenomic RNAs. This region, if placed within nonviral RNA, is capable of altering the binding potential of nonviral RNA to levels seen with wild-type vRNAs.
Prion Strain- and Species-Dependent Effects of Antiprion Molecules in Primary Neuronal Cultures
Authors: Cronier Sabrina , Beringue Vincent , Bellon Anne , Peyrin Jean-Michel , Laude Hubert
Published: October 2007

Transmissible spongiform encephalopathies (TSE) arise as a consequence of infection of the central nervous system by prions and are incurable. To date, most antiprion compounds identified by in vitro screening failed to exhibit therapeutic activity in animals, thus calling for new assays that could more accurately predict their in vivo potency. Primary nerve cell cultures are routinely used to assess neurotoxicity of chemical compounds. Here, we report that prion strains from different species can propagate in primary neuronal cultures derived from transgenic mouse lines overexpressing ovine, murine, hamster, or human prion protein. Using this newly developed cell system, the activity of three generic compounds known to cure prion-infected cell lines was evaluated. We show that the antiprion activity observed in neuronal cultures is species or strain dependent and recapitulates to some extent the activity reported in vivo in rodent models. Therefore, infected primary neuronal cultures may be a relevant system in which to investigate the efficacy and mode of action of antiprion drugs, including toward human transmissible spongiform encephalopathy agents.
Identification of Regions and Residues in Feline Junctional Adhesion Molecule Required for Feline Calicivirus Binding and Infection
Authors: Ossiboff Robert J. , Parker John S. L.
Published: October 2007

The feline junctional adhesion molecule A (fJAM-A) is a functional receptor for feline calicivirus (FCV). fJAM-A is a member of the immunoglobulin superfamily (IgSF) and consists of two Ig-like extracellular domains (D1 and D2), a membrane-spanning domain, and a short cytoplasmic tail. To identify regions of fJAM-A that interact with FCV, we purified recombinant fJAM-A ectodomain and D1 and D2 domains. We found that preincubation of FCV with the ectodomain or D1 was sufficient to inhibit FCV infection in plaque reduction assays. In enzyme-linked immunosorbent assays, FCV binding to fJAM-A ectodomain was concentration dependent and saturable; however, FCV bound D1 alone weakly and was unable to bind D2. To characterize FCV binding to surface-expressed fJAM-A, we transfected truncated and chimeric forms of fJAM-A into a nonpermissive cell line and assayed binding by flow cytometry. Only D1 was necessary for FCV binding to cells; all other domains could be replaced. Using a structure-guided mutational approach, we identified three mutants of fJAM-A within D1 (D42N, K43N, and S97A) that exhibited significantly decreased capacities to bind FCV. In contrast to our finding that D1 mediated FCV binding, we found that all domains of fJAM-A were necessary to confer susceptibility to FCV infection. Furthermore, surface expression of fJAM-A was not sufficient to permit FCV infection by all of the isolates we investigated. This indicates that (i) other cellular factors are required to permit productive FCV infection and (ii) individual FCV isolates differ in the factors they require.
Antiviral Antibodies Are Necessary To Prevent Cytotoxic T-Lymphocyte Escape in Mice Infected with a Coronavirus
Authors: Butler Noah S. , Dandekar Ajai A. , Perlman Stanley
Published: October 2007

Mutation within virus-derived CD8 T-cell epitopes can effectively abrogate cytotoxic T-lymphocyte (CTL) recognition and impede virus clearance in infected hosts. These so-called “CTL escape variant viruses” are commonly selected during persistent infections and are associated with rapid disease progression and increased disease severity. Herein, we tested whether antiviral antibody-mediated suppression of virus replication and subsequent virus clearance were necessary for preventing CTL escape in coronavirus-infected mice. We found that compared to wild-type mice, B-cell-deficient mice did not efficiently clear infectious virus, uniformly developed clinical disease, and harbored CTL escape variant viruses. These data directly demonstrate a critical role for antiviral antibody in protecting from the selective outgrowth of CTL escape variant viruses.
Ubiquitin Depletion and Dominant-Negative VPS4 Inhibit Rhabdovirus Budding without Affecting Alphavirus Budding
Authors: Taylor Gwen M. , Hanson Phyllis I. , Kielian Margaret
Published: October 2007

The budding reactions of a number of enveloped viruses use the cellular machinery involved in the formation of the luminal vesicles of endosomal multivesicular bodies (MVB). Budding of these viruses is dependent on the presence of specific late-domain motifs in membrane-associated viral proteins. Such budding reactions usually involve ubiquitin and are blocked by expression of an ATPase-deficient form of VPS4, a cellular AAA+ ATPase believed to be required late in the MVB pathway for the disassembly/release of the MVB machinery. Here we examined the role of the MVB pathway in the budding of the late-domain-containing rhabdovirus vesicular stomatitis virus (VSV) and the alphavirus Semliki Forest virus (SFV). We tested early and late steps in the MVB pathway by depleting ubiquitin with the proteasome inhibitor MG-132 and by using cell lines inducibly expressing VPS4A or VPS4B protein. As previously shown, VSV budding was strongly dependent on ubiquitin. In contrast to the findings of previous studies with VPS4A, expression of ATPase-deficient mutants of either VPS4A or VPS4B inhibited VSV budding. Inhibition by VPS4 required the presence of the PPPY late domain on the VSV matrix protein and resulted in the accumulation of nonreleased VSV particles at the plasma membrane. In contrast, SFV budding was independent of both ubiquitin and the activity of VPS4, perhaps reflecting the important role of the highly organized envelope protein lattice during alphavirus budding.
Temperature-Sensitive Mutations in the Putative Herpes Simplex Virus Type 1 Terminase Subunits pU
L
15 and pU
L
33 Preclude Viral DNA Cleavage/Packaging and Interaction with pU
L
28 at the Nonpermissive Temperature
Authors: Yang Kui , Poon Alice P. W. , Roizman Bernard , Baines Joel D.
Published: October 2007

Terminases comprise essential components of molecular motors required to package viral DNA into capsids in a variety of DNA virus systems. Previous studies indicated that the herpes simplex virus type 1 U
L
15 protein (pU
L
15) interacts with the pU
L
28 moiety of a pU
L
28-pU
L
33 complex to form the likely viral terminase. In the current study, a novel temperature-sensitive mutant virus was shown to contain a mutation in U
L
33 codon 61 predicted to change threonine to proline. At the nonpermissive temperature, this virus, designated ts8-22, replicated viral DNA and produced capsids that became enveloped at the inner nuclear membrane but failed to form plaques or to cleave or package viral DNA. Incubation at the nonpermissive temperature also precluded coimmunoprecipitation of U
L
33 protein with its normal interaction partners encoded by U
L
28 and U
L
15 in ts8-22-infected cells and with pU
L
28 in transient-expression assays. Moreover, a temperature-sensitive mutation in U
L
15 precluded coimmunoprecipitation of pU
L
15 with the U
L
28 and U
L
33 proteins at the nonpermissive temperature. We conclude that interactions between putative terminase components are tightly linked to successful viral DNA cleavage and packaging.
MEASUREMENT THE EFFECT OF γ-IRRADIATION DOSES ON AlCu8.5 BY POSITRON ANNIHILATION DOPPLER-BROADENING SPECTROSCOPY
Authors: ABDEL-RAHMAN M. A. , ABDEL-RAHMAN M. , ABO-ELSOUD M. , EISSA M. F. , LOTFY YAHIA A. , BADAWI EMAD A.
Published: October 2007

The effect of irradiation dose (kGy) on a set of AlCu 8.5 samples has been studied. The samples were irradiated to doses of 10, 30, 50, 70, 100, 300, 500, 700 and 1000 kGy of 60 Co γ-source at room temperature. The effect of γ-ray irradiation on the values of the S- and W-parameters reveals two stages. In the first stage, the S-parameter increases, while the W-parameter decreases up to 70 kGy. In the second stage, the S- and W-parameters decrease and increase respectively in the dose region from 100 to 1000 kGy. The dominant controlling mechanism of the S- and W-parameters was observed.
LEVEL REARRANGEMENT IN EXOTIC ATOMS AND QUANTUM DOTS
Authors: COMBESCURE MONIQUE , KHARE AVINASH , RAINA ASHOK K. , RICHARD JEAN-MARC , WEYDERT CAROLE
Published: October 2007

A presentation and a generalization are given of the phenomenon of level rearrangement. This occurs when an attractive long-range potential is perturbed by a short-range attractive potential as its strength is increased. This phenomenon was first discovered in condensed matter physics and has also been studied in the physics of exotic atoms. A similar phenomenon occurs in a model that we propose, inspired by quantum dots, where a short-range interaction is added to a harmonic confinement.
THE CONSENSUS VALUE FOR GAMES IN PARTITION FUNCTION FORM
Authors: JU YUAN
Published: October 2007

This paper studies a procedural and axiomatic extension of the consensus value [cf. Ju et al. (2007)] to the class of partition function form games. This value is characterized as the unique function that satisfies efficiency, complete symmetry, the quasi-null player property and additivity. By means of the transfer property, a second characterization is provided. Moreover, it is shown that the consensus value satisfies individual rationality under a superadditivity condition, and well balances the tradeoff between coalitional effects and externality effects. In this respect, explicit differences with other solution concepts are indicated.
WHEN ASPIRING AND RATIONAL AGENTS STRIVE TO COORDINATE
Authors: ROY JAIDEEP
Published: October 2007

The paper studies a game of common interest played infinitely many times between two players, one being aspiration driven while the other being a myopic optimizer. It is shown that the only two long run stationary outcomes are the two static equilibrium points. Robustness of long run behavior is studied to show that whenever the optimizer is allowed to make small mistakes, players are able to coordinate on the Pareto dominant equilibrium point most of the time in the long run if the speed of evolution of aspirations is sufficiently fast. However, when only the aspiring player is allowed to make small mistakes, achieving coordination is inevitable and independent of the speed at which aspirations evolve.
ON THE PAYOFF REPRESENTATIONS OF NORMAL FORM GAMES
Authors: OHNISHI KAZUHIRO
Published: October 2007

The literature on normal form games generally depicts the payoff matrices of two or three players. However, many such games discuss n-players. Therefore, this note studies the payoff representations of n-player normal form games.
ON TWO THEOREMS OF QUINZII AND RENT CONTROLLED HOUSING ALLOCATION IN SWEDEN
Authors: ERIKSSON KIMMO , SJÖSTRAND JONAS
Published: October 2007

The Swedish rent control system creates a white market for swapping rental contracts and a black market for selling rental contracts. Empirical data suggests that in this black-and-white market some people act according to utility functions that are both discontinuous and locally decreasing in money. We discuss Quinzii's theorem for the nonemptiness of the core of generalized house-swapping games, and show how it can be extended to cover the Swedish game.

In a second part, we show how this theorem of Quinzii and her second theorem on nonemptiness of the core in two-sided models are both special cases of a more general theorem.
WAGE NEGOTIATION UNDER GOOD FAITH BARGAINING
Authors: SCHWARTZ JESSE A. , WEN QUAN
Published: October 2007

We study the wage negotiation model of Haller and Holden (1990) and Fernandez and Glazer (1991) under the "Good Faith Bargaining" (GFB) rule, where a party may not demand more than it has previously demanded. The GFB rule significantly restricts feasible strategies, but at the same time, makes the game non-stationary and the analysis complicated. We introduce a state-dependent backward induction that generalizes Shaked and Sutton (1984) to characterize the equilibrium payoffs. We find that the GFB rule eliminates the union's credibility to strike. Without the strikes, the union's strategic opportunities during disagreement disappear, so that there is a unique equilibrium. This uniqueness contrasts sharply with the multiple equilibrium outcomes that obtain when no GFB rule is imposed.
Phenotypic properties of adult mouse intrinsic cardiac neurons maintained in culture
Authors: Hoard Jennifer L. , Hoover Donald B. , Wondergem Robert
Published: October 2007

Intrinsic cardiac neurons are core elements of a complex neural network that serves as an important integrative center for regulation of cardiac function. Although mouse models are used frequently in cardiovascular research, very little is known about mouse intrinsic cardiac neurons. Accordingly, we have dissociated neurons from adult mouse heart, maintained these cells in culture, and defined their basic phenotypic properties. Neurons in culture were primarily unipolar, and 89% had prominent neurite outgrowth after 3 days (longest neurite length of 258 ± 20 μm, n = 140). Many neurites formed close appositions with other neurons and nonneuronal cells. Neurite outgrowth was drastically reduced when neurons were kept in culture with a majority of nonneural cells eliminated. This finding suggests that nonneuronal cells release molecules that support neurite outgrowth. All neurons in coculture showed immunoreactivity for a full complement of cholinergic markers, but about 21% also stained for tyrosine hydroxylase, as observed previously in sections of intrinsic cardiac ganglia from mice and humans. Whole cell patch-clamp recordings demonstrated that these neurons have voltage-activated sodium current that is blocked by tetrodotoxin and that neurons exhibit phasic or accommodating patterns of action potential firing during a depolarizing current pulse. Several neurons exhibited a fast inward current mediated by nicotinic ACh receptors. Collectively, this work shows that neurons from adult mouse heart can be maintained in culture and exhibit appropriate phenotypic properties. Accordingly, these cultures provide a viable model for evaluating the physiology, pharmacology, and trophic factor sensitivity of adult mouse cardiac parasympathetic neurons.
Lin-7 targets the Kir 2.3 channel on the basolateral membrane via a L27 domain interaction with CASK
Authors: Alewine Christine , Kim Bo-young , Hegde Vandana , Welling Paul A.
Published: October 2007

Polarized expression of the Kir 2.3 channel in renal epithelial cells is influenced by the opposing activities of two different PDZ proteins. Mammalian Lin-7 (mLin-7) directly interacts with Kir 2.3 to coordinate basolateral membrane expression, whereas the tax interacting protein 1 (TIP-1), composed of a single PDZ domain, competes for interaction with mLin-7 and drives Kir 2.3 into the endocytic pathway. Here we show that the basolateral targeting function of mLin-7 depends on its L27 domain, which directs interaction with a cognate L27 domain in the basolateral membrane-anchoring protein, calcium/calmodulin-dependent serine protein kinase (CASK). In MDCK cells, the expression of an mLin-7 mutant that lacks the L27 domain displaced Kir 2.3 from the mLin-7/CASK complex and caused the channel to accumulate into large intracellular vesicles that partially colocalized with Rab-11. Conversely, transplantation of the mLin-7 L27 domain to TIP-1 conferred CASK interaction and basolateral targeting of Kir 2.3. Expression of the CASK L27 domain redistributed endogenous mLin-7 to an intracellular compartment and caused Kir 2.3 to accumulate in subapical endosomes. Taken together, these data support a model whereby mLin-7 acts as a PDZ-to-L27 adapter, mediating indirect association of Kir 2.3 with a basolateral membrane scaffold and thereby stabilizing Kir 2.3 at the basolateral membrane.
Gene expression of Na+/H+ exchanger in zebrafish H+-ATPase-rich cells during acclimation to low-Na+ and acidic environments
Authors: Yan Jia-Jiun , Chou Ming-Yi , Kaneko Toyoji , Hwang Pung-Pung
Published: October 2007

In mammalian nephrons, most of the Na+ and HCO3− is reabsorbed by proximal tubular cells in which the Na+/H+ exchanger 3 (NHE3) is the major player. The roles of NHEs in Na+ uptake/acid-base regulation in freshwater (FW) fish gills are still being debated. In the present study, functional genomic approaches were used to clone and sequence the full-length cDNAs of the nhe family from zebrafish ( Danio rerio). A phylogenetic tree analysis of the deduced amino acid sequences showed that zNHE1–8 are homologous to their mammalian counterparts. By RT-PCR analysis and double/triple in situ hybridization/immunocytochemistry, only zebrafish NHE3b was expressed in zebrafish gills and was colocalized with V-H+-ATPase but not with Na+-K+-ATPase, indicating that H+-ATPase-rich (HR) cells specifically express NHE3b. A subsequent quantitative RT-PCR analysis demonstrated that acclimation to low-Na+ FW caused upregulation and downregulation of the expressions of znhe3b and zatp6v0c (H+-ATPase C-subunit), respectively, in gill HR cells, whereas acclimation to acidic FW showed reversed effects on the expressions of these two genes. In conclusion, both NHE3b and H+-ATPase are probably involved in Na+ uptake/acid-base regulation in zebrafish gills, like mammalian kidneys, but the partitioning of these two transporters may be differentially regulated depending on the environmental situation in which fish are acclimatized.
Stable RNA interference of synaptotagmin I in PC12 cells results in differential regulation of transmitter release
Authors: Roden William H. , Papke Jason B. , Moore Johnnie M. , Cahill Anne L. , Macarthur Heather , Harkins Amy B.
Published: October 2007

In sympathetic neurons, it is well-established that the neurotransmitters, norepinephrine (NE), neuropeptide Y (NPY), and ATP are differentially coreleased from the same neurons. In this study, we determined whether synaptotagmin (syt) I, the primary Ca2+ sensor for regulated release, could function as the protein that differentially regulates release of these neurotransmitters. Plasmid-based RNA interference was used to specifically and stably silence expression of syt I in a model secretory cell line. Whereas stimulated release of NPY and purines was abolished, stimulated catecholamine (CA) release was only reduced by ∼50%. Although expression levels of tyrosine hydroxylase, the rate-limiting enzyme in the dopamine synthesis pathway, was unaffected, expression of the vesicular monoamine transporter 1 was reduced by 50%. To evaluate whether NPY and CAs are found within the same vesicles and whether syt I is found localized to each of these NPY- and CA-containing vesicles, we used immunocytochemistry to determine that syt I colocalized with large dense core vesicles, with NPY, and with CAs. Furthermore, both CAs and NPY colocalized with one another and with large dense core vesicles. Electron micrographs show that large dense core vesicles are synthesized and available for release in cells that lack syt I. These results are consistent with syt I regulating differential release of transmitters.
Biological role, protein expression, subcellular localization, and oxidative stress response of paraoxonase 2 in the intestine of humans and rats
Authors: Levy Emile , Trudel Karine , Bendayan Moise , Seidman Ernest , Delvin Edgard , Elchebly Mounib , Lavoie Jean-Claude , Precourt Louis-Philippe , Amre Devendra , Sinnett Daniel
Published: October 2007

Oxidative stress is a cardinal manifestation of various intestinal disorders. However, very little knowledge is available on the intestine's inherent defense mechanisms against free radicals. This study was designed to determine the protein expression, subcellular localization and oxidative stress response of paraoxonase 2 (PON2), a member of a powerful antioxidant family in human and rat intestine. Biochemical and ultrastructural experiments all showed a substantial expression of PON2 in human and rat intestine. Western blot analysis disclosed higher levels of PON2 in the jejunum than in the duodenum, ileum, and colon. Cell fractionation revealed a predominant PON2 association with microsomes and lysosomes in the human jejunum, which differed from that in rats. PON2 was detected in the intestine as early as week 15 of gestation and was significantly increased by week 20. Iron ascorbate-mediated lipid peroxidation induced a marked decrease in PON2 expression in intestinal specimens coincidental to an abundant rise in malondialdehyde (MDA). On the other hand, preincubation with potent antioxidants, such as butylated hydroxytoluene, Trolox, and N-acetylcysteine, prevented iron-ascorbate-generating PON2 reduction in parallel with MDA suppression. Finally, the preincubation of permeabilized Caco-2 cells with purified PON2 led to a protection against iron-ascorbate-induced lipid peroxidation. These observations demonstrate that the human intestine is preferentially endowed with a marked PON2 expression compared with the rat intestine and this expression shows a developmental and intracellular pattern of distribution. Furthermore, our observations suggest PON2 protective effects against prooxidant stimuli in the small intestine.
Purinergic control of apical plasma membrane PI(4,5)P2levels sets ENaC activity in principal cells
Authors: Pochynyuk Oleh , Bugaj Vladislav , Vandewalle Alain , Stockand James D.
Published: October 2007

Activity of the epithelial sodium channel (ENaC) is limiting for Na+reabsorption at the distal nephron. Phosphoinositides, such as phosphatidylinositol 4,5-biphosphate [PI(4,5)P2] modulate the activity of this channel. Activation of purinergic receptors triggers multiple events, including activation of PKC and PLC, with the latter depleting plasma membrane PI(4,5)P2. Here, we investigate regulation of ENaC in renal principal cells by purinergic receptors via PLC and PI(4,5)P2. Purinergic signaling rapidly decreases ENaC open probability and apical membrane PI(4,5)P2levels with similar time courses. Moreover, inhibiting purinergic signaling with suramin rescues ENaC activity. The PLC inhibitor U73122, but not U73343, its inactive analog, recapitulates the action of suramin. In contrast, modulating PKC signaling failed to affect purinergic regulation of ENaC. Unexpectedly, inhibiting either purinergic receptors or PLC in resting cells dramatically increased ENaC activity above basal levels, indicating tonic activation of purinergic signaling in these polarized renal epithelial cells. Increased ENaC activity was associated with elevation of apical membrane PI(4,5)P2levels. Subsequent treatment with ATP in the presence of inhibited purinergic signaling failed to decrease ENaC activity and apical membrane PI(4,5)P2levels. Dwell-time analysis reveals that depletion of PI(4,5)P2forces ENaC toward a closed state. In contrast, increasing PI(4,5)P2levels above basal values locks the channel in an open state interrupted by brief closings. Thus our results suggest that purinergic control of apical membrane PI(4,5)P2levels is a major regulator of ENaC activity in renal epithelial cells.
Responses of Inferior Colliculus Neurons to Double Harmonic Tones
Authors: Sinex Donal G. , Li Hongzhe
Published: October 2007

The auditory system can segregate sounds that overlap in time and frequency, if the sounds differ in acoustic properties such as fundamental frequency (f0). However, the neural mechanisms that underlie this ability are poorly understood. Responses of neurons in the inferior colliculus (IC) of the anesthetized chinchilla were measured. The stimuli were harmonic tones, presented alone (single harmonic tones) and in the presence of a second harmonic tone with a different f0 (double harmonic tones). Responses to single harmonic tones exhibited no stimulus-related temporal pattern, or in some cases, a simple envelope modulated at f0. Responses to double harmonic tones exhibited complex slowly modulated discharge patterns. The discharge pattern varied with the difference in f0 and with characteristic frequency. The discharge pattern also varied with the relative levels of the two tones; complex temporal patterns were observed when levels were equal, but as the level difference increased, the discharge pattern reverted to that associated with single harmonic tones. The results indicated that IC neurons convey information about simultaneous sounds in their temporal discharge patterns and that the patterns are produced by interactions between adjacent components in the spectrum. The representation is “low-resolution,” in that it does not convey information about single resolved components from either individual sound.
Sustained Rhythmic Activity in Gap-Junctionally Coupled Networks of Model Neurons Depends on the Diameter of Coupled Dendrites
Authors: Gansert Juliane , Golowasch Jorge , Nadim Farzan
Published: October 2007

Gap junctions are known to be important for many network functions such as synchronization of activity and the generation of waves and oscillations. Gap junctions have also been proposed to be essential for the generation of early embryonic activity. We have previously shown that the amplitude of electrical signals propagating across gap-junctionally coupled passive cables is maximized at a unique diameter. This suggests that threshold-dependent signals may propagate through gap junctions for a finite range of diameters around this optimal value. Here we examine the diameter dependence of action potential propagation across model networks of dendro-dendritically coupled neurons. The neurons in these models have passive soma and dendrites and an action potential-generating axon. We show that propagation of action potentials across gap junctions occurs only over a finite range of dendritic diameters and that propagation delay depends on this diameter. Additionally, in networks of gap-junctionally coupled neurons, rhythmic activity can emerge when closed loops (re-entrant paths) occur but again only for a finite range of dendrite diameters. The frequency of such rhythmic activity depends on the length of the path and the dendrite diameter. For large networks of randomly coupled neurons, we find that the re-entrant paths that underlie rhythmic activity also depend on dendrite diameter. These results underline the potential importance of dendrite diameter as a determinant of network activity in gap-junctionally coupled networks, such as network rhythms that are observed during early nervous system development.
NMR Structure and CD Titration with Metal Cations of Human Prionα2-Helix-Related Peptides
Authors: Ronga Luisa , Palladino Pasquale , Saviano Gabriella , Tancredi Teodorico , Benedetti Ettore , Ragone Raffaele , Rossi Filomena
Published: October 2007

The 173–195 segment corresponding to the helix 2 of the C-globular prion protein domain could be one of several “spots” of intrinsic conformational flexibility. In fact, it possesses chameleon conformational behaviour and gathers several disease-associated point mutations. We have performed spectroscopic studies on the wild-type fragment 173–195 and on its D178N mutant dissolved in trifluoroethanol to mimic the in vivo system, both in the presence and in the absence of metal cations. NMR data showed that the structure of the D178N mutant is characterized by two short helices separated by a kink, whereas the wild-type peptide is fully helical. Both peptides retained these structural organizations, as monitored by CD, in the presence of metal cations. NMR spectra were however not in favour of the formation of definite ion-peptide complexes. This agrees with previous evidence that other regions of the prion protein are likely the natural target of metal cation binding.
Logarithm of the Discrete Fourier Transform
Authors: Aristidou Michael , Hanson Jason
Published: October 2007

The discrete Fourier transform defines a unitary matrix operator. The logarithm of this operator is computed, along with the projection maps onto its eigenspaces. A geometric interpretation of the discrete Fourier transform is also given.
Total Variation Regularization of Matrix‐Valued Images
Authors: Christiansen Oddvar , Lee Tin-Man , Lie Johan , Sinha Usha , Chan Tony F.
Published: October 2007

We generalize the total variation restoration model, introduced by Rudin, Osher, and Fatemi in 1992, to matrix‐valued data, in particular, to diffusion tensor images (DTIs). Our model is a natural extension of the color total variation model proposed by
Blomgren and Chan in 1998. We treat the diffusion matrix D implicitly as the product D = LLT, and work with the elements of L as variables, instead of working directly on the elements of D. This ensures positive definiteness of the tensor during the regularization flow, which is essential when regularizing DTI. We perform numerical experiments on both synthetical data and 3D human brain DTI, and measure the quantitative behavior of the proposed model.
An Integrated 5 GHz Wideband Quadrature Modem for OFDM Gbit/s Transmission in SiGe:C BiCMOS
Authors: Schmalz Klaus , Grass Eckard , Herzel Frank , Piz Maxim
Published: October 2007

This paper presents a 5 GHz wideband I/Q modulator/demodulator for 650 MHz OFDM signal bandwidth, which is integrated with a 5 GHz phase locked loop for I/Q generation. The quadrature signals are derived from a 10 GHz CMOS VCO followed by a bipolar frequency divider. The phase noise at 1 MHz offset is
−112 dBc/Hz for the modulator as well as for the demodulator. The chips were produced in a 0.25 μm SiGe BiCMOS technology. The signal-to-noise ratio (SNR) of transmitted/received OFDM signal and the corresponding I/Q mismatch versus baseband frequency are given. The modulator achieves an SNR of 22–23 dB, and the demodulator realizes an SNR up to 22 dB. The modulator reaches a data rate of 2.16 Gbit/s using 64 QAM OFDM, and the demodulator realizes 1.92 Gbits/s.
Magnetic Field Distribution and Signal Decay in Functional MRI in Very High Fields (up to 9.4 T) Using Monte Carlo Diffusion Modeling
Authors: Mueller-Bierl Bernd Michael , Uludag Kamil , Pereira Philippe L. , Schick Fritz
Published: October 2007

Extravascular signal decay rate R2 or R2∗ as a function of blood oxygenation, geometry, and field strength was calculated using a Monte Carlo (MC) algorithm for a wider parameter
range than hitherto by others. The relaxation rates of gradient‐recalled‐echo (GRE) and Hahn‐spin‐echo
(HSE) imaging in the presence of blood vessels (ranging from capillaries to veins) have been computed
for a wide range of field strengths up to 9.4 T and 50% blood deoxygenation. The maximum HSE decay
was found to be shifted to lower radii in higher compared to lower field strengths. For GRE, however, the
relaxation rate was greatest for large vessels at any field strength. In addition, assessments of computational
reliability have been carried out by investigating the influence of the time step, the Monte Carlo step procedure,
boundary conditions, the number of angles between the vessel and the exterior field B0, the influence of
neighboring vessels having the same orientation as the central vessel, and the number of proton spins.
The results were compared with those obtained from a field distribution of the vessel computed by an analytic
formula describing the field distribution of an ideal object (an infinitely long cylinder). It was found that the
time step is not critical for values equal to or lower than 200 microseconds. The choice of the MC step procedure
(three‐dimensional Gaussian diffusion, constant one‐ or three‐dimensional diffusion step) also failed to
influence the results significantly; in contrast, the free boundary conditions, as well as taking too few angles
into account, did introduce errors. Next neighbor vessels with the same orientation as the main vessel did
not contribute significantly to signal decay. The total number of particles simulated was also found to play
a minor role in computing R2/ R2∗.
Contributions of Inflammatory Processes to the Development of the Early Stages of Diabetic Retinopathy
Authors: Kern Timothy S.
Published: October 2007

Diabetes causes metabolic and physiologic abnormalities in the retina, and these changes suggest a role for inflammation in the development of diabetic retinopathy. These changes include upregulation of iNOS, COX‐2, ICAM‐1, caspase 1, VEGF, and NF‐κB, increased production of nitric oxide, prostaglandin E2, IL‐1β, and cytokines, as well as increased permeability and leukostasis. Using selective pharmacologic inhibitors or genetically modified animals, an increasing number of therapeutic approaches have been identified that significantly inhibit development of at least the early stages of diabetic retinopathy, especially occlusion and degeneration of retinal capillaries. A common feature of a number of these therapies is that they inhibit production of inflammatory mediators. The concept that localized inflammatory processes play a role in the development of diabetic retinopathy is relatively new, but evidence that supports the hypothesis is accumulating rapidly. This new hypothesis offers new insight into the pathogenesis of diabetic retinopathy, and offers novel targets to inhibit the ocular disease.