bluuebunny/crossref_metadata_2025 huggingface dataset:
Activation of NF-κB by the Latent vFLIP Gene of Kaposi's Sarcoma-Associated Herpesvirus Is Required for the Spindle Shape of Virus-Infected Endothelial Cells and Contributes to Their Proinflammatory Phenotype
Authors: Grossmann Claudia , Podgrabinska Simona , Skobe Mihaela , Ganem Don
Published: June 2006

Kaposi's sarcoma (KS) is an inflammatory angioproliferative lesion induced by the infection of endothelial cells with the KS-associated herpesvirus (KSHV). Infected endothelial cells assume an elongated (spindle) shape that is one of the histologic signatures of KS. In vitro, latent viral infection of primary endothelial cells (but no other cell type) strikingly recapitulates these morphological findings. Here we report that the spindling phenotype involves major rearrangement of the actin cytoskeleton and can be attributed to the expression of a single viral protein, vFLIP, a known activator of NF-κB. Consistent with this, the inhibition of NF-κB activation blocks vFLIP-induced spindling in cultured endothelial cells. vFLIP expression in spindle cells also induces the production of a variety of proinflammatory cytokines and cell surface adhesion proteins that likely contribute to the inflammatory component of KS lesions.
Role of Invariant Thr80 in Human Immunodeficiency Virus Type 1 Protease Structure, Function, and Viral Infectivity
Authors: Foulkes Jennifer E. , Prabu-Jeyabalan Moses , Cooper Deyna , Henderson Gavin J. , Harris Janera , Swanstrom Ronald , Schiffer Celia A.
Published: June 2006

Sequence variability associated with human immunodeficiency virus type 1 (HIV-1) is useful for inferring structural and/or functional constraints at specific residues within the viral protease. Positions that are invariant even in the presence of drug selection define critically important residues for protease function. While the importance of conserved active-site residues is easily understood, the role of other invariant residues is not. This work focuses on invariant Thr80 at the apex of the P1 loop of HIV-1, HIV-2, and simian immunodeficiency virus protease. In a previous study, we postulated, on the basis of a molecular dynamics simulation of the unliganded protease, that Thr80 may play a role in the mobility of the flaps of protease. In the present study, both experimental and computational methods were used to study the role of Thr80 in HIV protease. Three protease variants (T80V, T80N, and T80S) were examined for changes in structure, dynamics, enzymatic activity, affinity for protease inhibitors, and viral infectivity. While all three variants were structurally similar to the wild type, only T80S was functionally similar. Both T80V and T80N had decreased the affinity for saquinavir. T80V significantly decreased the ability of the enzyme to cleave a peptide substrate but maintained infectivity, while T80N abolished both activity and viral infectivity. Additionally, T80N decreased the conformational flexibility of the flap region, as observed by simulations of molecular dynamics. Taken together, these data indicate that HIV-1 protease functions best when residue 80 is a small polar residue and that mutations to other amino acids significantly impair enzyme function, possibly by affecting the flexibility of the flap domain.
Passive Sexual Transmission of Human Immunodeficiency Virus Type 1 Variants and Adaptation in New Hosts
Authors: Frater A. J. , Edwards C. T. T. , McCarthy N. , Fox J. , Brown H. , Milicic A. , Mackie N. , Pillay T. , Drijfhout J. W. , Dustan S. , Clarke J. R. , Holmes E. C. , Zhang H. T. , Pfafferott K. , Goulder P. J. , McClure M. O. , Weber J. , Phillips R. E. , Fidler S.
Published: June 2006

Human immunodeficiency virus type 1 (HIV-1) genetic diversity is a major obstacle for the design of a successful vaccine. Certain viral polymorphisms encode human leukocyte antigen (HLA)-associated immune escape, potentially overcoming limited vaccine protection. Although transmission of immune escape variants has been reported, the overall extent to which this phenomenon occurs in populations and the degree to which it contributes to HIV-1 viral evolution are unknown. Selection on the HIV-1
env
gene at transmission favors neutralization-sensitive variants, but it is not known to what degree selection acts on the internal HIV-1 proteins to restrict or enhance the transmission of immune escape variants. Studies have suggested that HLA class I may determine susceptibility to HIV-1 infection, but a definitive role for HLA at transmission remains unproven. Comparing populations of acute seroconverters and chronically infected patients, we found no evidence of selection acting to restrict transmission of HIV-1 variants. We found that statistical associations previously reported in chronic infection between viral polymorphisms and HLA class I alleles are not present in acute infection, suggesting that the majority of viral polymorphisms in these patients are the result of transmission rather than de novo adaptation. Using four episodes of HIV-1 transmission in which the donors and recipients were both sampled very close to the time of infection we found that, despite a transmission bottleneck, genetic variants of HIV-1 infection are transmitted in a frequency-dependent manner. As HIV-1 infections are seeded by unique donor-adapted viral variants, each episode is a highly individual antigenic challenge. Host-specific, idiosyncratic HIV-1 antigenic diversity will seriously tax the efficacy of immunization based on consensus sequences.
Involvement of Novel Human Immunodeficiency Virus Type 1 Reverse Transcriptase Mutations in the Regulation of Resistance to Nucleoside Inhibitors
Authors: Svicher Valentina , Sing Tobias , Santoro Maria Mercedes , Forbici Federica , Rodríguez-Barrios Fátima , Bertoli Ada , Beerenwinkel Niko , Bellocchi Maria Concetta , Gago Federigo , d'Arminio Monforte Antonella , Antinori Andrea , Lengauer Thomas , Ceccherini-Silberstein Francesca , Perno Carlo Federico
Published: June 2006

We characterized 16 additional mutations in human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) whose role in drug resistance is still unknown by analyzing 1,906 plasma-derived HIV-1 subtype Bpolsequences from 551 drug-naïve patients and 1,355 nucleoside RT inhibitor (NRTI)-treated patients. Twelve mutations positively associated with NRTI treatment strongly correlated both in pairs and in clusters with known NRTI resistance mutations on divergent evolutionary pathways. In particular, T39A, K43E/Q, K122E, E203K, and H208Y clustered with the nucleoside analogue mutation 1 cluster (NAM1; M41L+L210W+T215Y). Their copresence in this cluster was associated with an increase in thymidine analogue resistance. Moreover, treatment failure in the presence of K43E, K122E, or H208Y was significantly associated with higher viremia and lower CD4 cell count. Differently, D218E clustered with the NAM2 pathway (D67N+K70R+K219Q+T215F), and its presence in this cluster determined an increase in zidovudine resistance. In contrast, three mutations (V35I, I50V, and R83K) negatively associated with NRTI treatment showed negative correlations with NRTI resistance mutations and were associated with increased susceptibility to specific NRTIs. In particular, I50V negatively correlated with the lamivudine-selected mutation M184V and was associated with a decrease in M184V/lamivudine resistance, whereas R83K negatively correlated with both NAM1 and NAM2 clusters and was associated with a decrease in thymidine analogue resistance. Finally, the association pattern of the F214L polymorphism revealed its propensity for the NAM2 pathway and its strong negative association with the NAM1 pathway. Our study provides evidence of novel RT mutational patterns that regulate positively and/or negatively NRTI resistance and strongly suggests that other mutations beyond those currently known to confer resistance should be considered for improved prediction of clinical response to antiretroviral drugs.
Cross-Clade Neutralizing Activity of Human Anti-V3 Monoclonal Antibodies Derived from the Cells of Individuals Infected with Non-B Clades of Human Immunodeficiency Virus Type 1
Authors: Gorny Miroslaw K. , Williams Constance , Volsky Barbara , Revesz Kathy , Wang Xiao-Hong , Burda Sherri , Kimura Tetsuya , Konings Frank A. J. , Nádas Arthur , Anyangwe Christopher A. , Nyambi Phillipe , Krachmarov Chavdar , Pinter Abraham , Zolla-Pazner Susan
Published: June 2006

The majority of global human immunodeficiency virus infections are caused by viruses characterized by a GPGQ motif at the tip of the V3 loop. Characterization of anti-V3 monoclonal antibodies (MAbs) that neutralize isolates with the GPGQ V3 motif is an important step in designing vaccines that will induce such Abs. Consequently, seven human anti-V3 MAbs derived from the cells of individuals infected with non-B-subtype viruses (anti-V3non-BMAbs) were generated from the cells of individuals from Africa infected with circulating recombinant forms CRF02_AG, CRF09_cpx, and CRF13_cpx, each of which contains a subtype Aenvgene. Sequence analysis of plasma viruses revealed a GPGQ motif at the apex of the V3 loop from six of the seven subjects and a GPGR motif from one subject. The MAbs were selected with fusion proteins (FP) containing V392UG037.8or V3JR-CSFfrom subtype A or B, respectively. In virus binding assays, five of the seven (71%) anti-V3non-BMAbs bound to V3-FPs from both subtype A and subtype B, while only four of the nine (44%) anti-V3BMAbs recognized both V3-FPs. Using two neutralization assays, both the anti-V3non-Band the anti-V3BMAbs neutralized subtype B viruses with similar activities, while the anti-V3non-BMAbs exhibited a tendency toward both increased potency and breadth of neutralization against non-B viruses compared to anti-V3BMAbs. Statistical significance was not achieved, due in large measure to the sizes of the MAb panels, but the overall pattern of data strongly suggests that viruses with the GPGQ motif at the tip of the V3 loop induce anti-V3 Abs with broader cross-neutralizing activity than do viruses with the GPGR motif.
Deregulation of eIF4E: 4E-BP1 in Differentiated Human Papillomavirus-Containing Cells Leads to High Levels of Expression of the E7 Oncoprotein
Authors: Oh Kwang-Jin , Kalinina Anna , Park No-Hee , Bagchi Srilata
Published: June 2006

Infections with high-risk human papillomaviruses (HPVs) are linked to more than 95% of cervical cancers. HPVs replicate exclusively in differentiated cells and the function of the HPV E7 oncoprotein is essential for viral replication. In this study, we investigated the mechanism that regulates E7 expression in differentiated cells. The level of E7 protein was strongly induced in HPV-containing Caski, HOK-16B, and BaP-T cells during growth in methylcellulose-containing medium, a condition that induces differentiation. Enhanced expression of E7 was observed between 4 and 8 h of culturing in methylcellulose and was maintained for up to 24 h. The increase was not due to altered stability of the E7 protein or an increase in the steady-state level of the E7 mRNA. Instead, the translation of the E7 mRNA was enhanced during differentiation. More than 70 to 80% of the E7 mRNA was found in the polysome fractions in the differentiated cells. Consistent with this observation, higher levels of the phosphorylated translator inhibitor 4E-BP1 were observed in differentiated HPV-containing cells but not in differentiated non-HPV tumor cells or primary keratinocytes. The mTOR kinase inhibitor rapamycin blocked phosphorylation of 4E-BP1 and significantly decreased the level of E7 protein in Caski cells, suggesting that phosphorylation of 4E-BP1 is linked to E7 expression. Prevailing models for the molecular mechanisms underlying E7 expression have focused largely on transcriptional regulation. The results presented in this study demonstrate a significant role of the cellular translation machinery to maintain a high level of E7 protein in differentiated cells.
“Self” and “Nonself” Manipulation of Interferon Defense during Persistent Infection: Bovine Viral Diarrhea Virus Resists Alpha/Beta Interferon without Blocking Antiviral Activity against Unrelated Viruses Replicating in Its Host Cells
Authors: Schweizer Matthias , Mätzener Philippe , Pfaffen Gabriela , Stalder Hanspeter , Peterhans Ernst
Published: June 2006

Bovine viral diarrhea virus
(BVDV), together with
Classical swine fever virus
(CSFV) and
Border disease virus
(BDV) of sheep, belongs to the genus
Pestivirus
of the
Flaviviridae
. BVDV is either cytopathic (cp) or noncytopathic (ncp), as defined by its effect on cultured cells. Infection of pregnant animals with the ncp biotype may lead to the birth of persistently infected calves that are immunotolerant to the infecting viral strain. In addition to evading the adaptive immune system, BVDV evades key mechanisms of innate immunity. Previously, we showed that ncp BVDV inhibits the induction of apoptosis and alpha/beta interferon (IFN-α/β) synthesis by double-stranded RNA (dsRNA). Here, we report that (i) both ncp and cp BVDV block the induction by dsRNA of the Mx protein (which can also be induced in the absence of IFN signaling); (ii) neither biotype blocks the activity of IFN; and (iii) once infection is established, BVDV is largely resistant to the activity of IFN-α/β but (iv) does not interfere with the establishment of an antiviral state induced by IFN-α/β against unrelated viruses. The results of our study suggest that, in persistent infection, BVDV is able to evade a central element of innate immunity directed against itself without generally compromising its activity against unrelated viruses (“nonself”) that may replicate in cells infected with ncp BVDV. This highly selective “self” and “nonself” model of evasion of the interferon defense system may be a key element in the success of persistent infection in addition to immunotolerance initiated by the early time point of fetal infection.
Cross-Subtype T-Cell Immune Responses Induced by a Human Immunodeficiency Virus Type 1 Group M Consensus Env Immunogen
Authors: Weaver Eric A. , Lu Zhongjing , Camacho Zenaido T. , Moukdar Fatiha , Liao Hua-Xin , Ma Ben-Jiang , Muldoon Mark , Theiler James , Nabel Gary J. , Letvin Norman L. , Korber Bette T. , Hahn Beatrice H. , Haynes Barton F. , Gao Feng
Published: June 2006

The genetic diversity among globally circulating human immunodeficiency virus type 1 (HIV-1) strains is a serious challenge for HIV-1 vaccine design. We have generated a synthetic group M consensusenvgene (CON6) for induction of cross-subtype immune responses and report here a comparative study of T-cell responses to this and natural strainenvimmunogens in a murine model. Three different strains of mice were immunized with CON6 as well as subtype A, B, or Cenvimmunogens, using a DNA prime-recombinant vaccinia virus boost strategy. T-cell epitopes were mapped by gamma interferon enzyme-linked immunospot analysis using five overlapping Env peptide sets from heterologous subtype A, B, and C viruses. The CON6-derived vaccine was immunogenic and induced a greater number of T-cell epitope responses than any single wild-type subtype A, B, and Cenvimmunogen and similar T-cell responses to a polyvalent vaccine. The responses were comparable to within-clade responses but significantly more than between-clade responses. The magnitude of the T-cell responses induced by CON6 (measured by individual epitope peptides) was also greater than the magnitude of responses induced by individual wild-typeenvimmunogens. Though the limited major histocompatibility complex repertoire in inbred mice does not necessarily predict responses in nonhuman primates and humans, these results suggest that synthetic centralizedenvimmunogens represent a promising approach for HIV-1 vaccine design that merits further characterization.
Humoral Responses against Coimmunized Protein Antigen but Not against Alphavirus-Encoded Antigens Require Alpha/Beta Interferon Signaling
Authors: Hidmark Åsa S. , Nordström Eva K. L. , Dosenovic Pia , Forsell Mattias N. E. , Liljeström Peter , Karlsson Hedestam Gunilla B.
Published: June 2006

Viruses typically elicit potent adaptive immune responses, and live-virus-based vaccines are among the most efficient human vaccines known. The mechanisms by which viruses stimulate adaptive immune responses are not fully understood, but activation of innate immune signaling pathways in the early phase of the infection may be of importance. In addition to stimulating immune responses to viral antigens expressed in infected cells, viruses can also provide adjuvant signals to coimmunized protein antigens. Using recombinant Semliki Forest virus (rSFV)-based vaccines, we show that rSFV potently enhanced antibody responses against coimmunized protein antigens in the absence of other exogenously added adjuvants. Elicitation of antibody responses against both virus-encoded antigens and coimmunized protein antigens was independent of the signaling via Toll-like receptors (TLRs) previously implicated in antiviral responses. In contrast, the adjuvant effect of rSFV on coimmunized protein was completely abolished in mice lacking the alpha/beta interferon (IFN-α/β) receptor (IFN-AR1), demonstrating that IFN-α/β signaling was critical for mediating this effect. Antibody responses directed against virus-encoded antigens were intact in IFN-AR1
−/−
mice, suggesting that other signals are sufficient to drive immune responses against virally encoded antigens. These data provide a basis for the adjuvant effect of rSFV and show that different signals are required to stimulate antibody responses to virally encoded antigens and to antigens administered as purified protein vaccines, together with viral particles.
Evolutionary History of the Closely Related Group 2 Coronaviruses: Porcine Hemagglutinating Encephalomyelitis Virus, Bovine Coronavirus, and Human Coronavirus OC43
Authors: Vijgen Leen , Keyaerts Els , Lemey Philippe , Maes Piet , Van Reeth Kristien , Nauwynck Hans , Pensaert Maurice , Van Ranst Marc
Published: June 2006

The close genetic and antigenic relatedness among the group 2 coronaviruses human coronavirus OC43 (HCoV-OC43), bovine coronavirus (BCoV), and porcine hemagglutinating encephalomyelitis virus (PHEV) suggests that these three viruses with different host specificities diverged fairly recently. In this study, we determined the complete genomic sequence of PHEV (strain PHEV-VW572), revealing the presence of a truncated group 2-specific ns2 gene in PHEV in comparison to other group 2 coronaviruses. Using a relaxed molecular clock approach, we reconstructed the evolutionary relationships between PHEV, BCoV, and HCoV-OC43 in real-time units, which indicated relatively recent common ancestors for these species-specific coronaviruses.
Distinct Roles for Nucleic Acid in In Vitro Assembly of Purified Mason-Pfizer Monkey Virus CANC Proteins
Authors: Ulbrich Pavel , Haubova Sarka , Nermut Milan V. , Hunter Eric , Rumlova Michaela , Ruml Tomas
Published: June 2006

In contrast to other retroviruses, Mason-Pfizer monkey virus (M-PMV) assembles immature capsids in the cytoplasm. We have compared the ability of minimal assembly-competent domains from M-PMV and human immunodeficiency virus type 1 (HIV-1) to assemble in vitro into virus-like particles in the presence and absence of nucleic acids. A fusion protein comprised of the capsid and nucleocapsid domains of Gag (CANC) and its N-terminally modified mutant (ΔProCANC) were used to mimic the assembly of the viral core and immature particles, respectively. In contrast to HIV-1, where CANC assembled efficiently into cylindrical structures, the same domains of M-PMV were assembly incompetent. The addition of RNA or oligonucleotides did not complement this defect. In contrast, the M-PMV ΔProCANC molecule was able to assemble into spherical particles, while that of HIV-1 formed both spheres and cylinders. For M-PMV, the addition of purified RNA increased the efficiency with which ΔProCANC formed spherical particles both in terms of the overall amount and the numbers of completed spheres. The amount of RNA incorporated was determined, and for both rRNA and MS2-RNA, quantities similar to that of genomic RNA were encapsidated. Oligonucleotides also stimulated assembly; however, they were incorporated into ΔProCANC spherical particles in trace amounts that could not serve as a stoichiometric structural component for assembly. Thus, oligonucleotides may, through a transient interaction, induce conformational changes that facilitate assembly, while longer RNAs appear to facilitate the complete assembly of spherical particles.
Vaccinia Virus Intermediate and Late Promoter Elements Are Targeted by the TATA-Binding Protein
Authors: Knutson Bruce A. , Liu Xu , Oh Jaewook , Broyles Steven S.
Published: June 2006

Vaccinia virus replicates in the cytoplasm of the host cell and encodes its own RNA polymerase and transcription factors. The proteins that target the poxvirus RNA polymerase to intermediate- and late-class promoters have not been identified. In this study, representatives of the intermediate and late promoters were characterized at the nucleotide level to identify essential motifs. Both intermediate and late viral promoters are shown to have an essential element suggestive of TATA boxes, which are potential targets for the TATA-binding protein (TBP). Several approaches were used to test for TBP requirement in vaccinia virus transcription, including overexpression of TBP, expression of a dominant negative mutant of TBP, RNA interference, and expression of adenovirus E1A protein, which inactivates TBP. In each case, the results support an essential role for TBP in vaccinia virus intermediate- and late-gene transcription. These findings indicate that poxviruses have integrated TBP as a central feature into an otherwise heterologous transcription system. A model for transcriptional switching, in which both intermediate and late promoter elements are targeted by TBP that recruits viral transcription factors to assemble a functional complex on their cognate promoters and a dysfunctional, repressed complex on the other class, is proposed.
Conformational States of the Severe Acute Respiratory Syndrome Coronavirus Spike Protein Ectodomain
Authors: Li Fang , Berardi Marcelo , Li Wenhui , Farzan Michael , Dormitzer Philip R. , Harrison Stephen C.
Published: June 2006

The severe acute respiratory syndrome coronavirus enters cells through the activities of a spike protein (S) which has receptor-binding (S1) and membrane fusion (S2) regions. We have characterized four sequential states of a purified recombinant S ectodomain (S-e) comprising S1 and the ectodomain of S2. They are S-e monomers, uncleaved S-e trimers, cleaved S-e trimers, and dissociated S1 monomers and S2 trimer rosettes. Lowered pH induces an irreversible transition from flexible, L-shaped S-e monomers to clove-shaped trimers. Protease cleavage of the trimer occurs at the S1-S2 boundary; an ensuing S1 dissociation leads to a major rearrangement of the trimeric S2 and to formation of rosettes likely to represent clusters of elongated, postfusion trimers of S2 associated through their fusion peptides. The states and transitions of S suggest conformational changes that mediate viral entry into cells.
A prospective cohort study of injury in amateur and professional boxing
Authors: Zazryn T , Cameron P , McCrory P
Published: June 2006

Background:There is concern over the potential for a high incidence of injury in boxing. This is despite a lack of prospective data evaluating the risk for modern day participants. Updated, reliable data with a focus on potential exposure to injury for both amateur and, especially, professional boxers is required.

Aim:To determine the epidemiology of injury and exposure of amateur and professional boxers in Victoria, Australia.

Methods:A prospective cohort study with one year follow up was carried out over 2004–2005. Thirty three amateur and 14 active professional boxers registered with either Boxing Victoria Inc (amateurs) or the Professional Boxing and Combat Sports Board of Victoria (professionals) volunteered. Exposure at training and competition was measured, and any injuries sustained during this participation were recorded.

Results:Twenty one injuries were sustained by the cohort during the follow up period. Most were to the head region (71%; 95% confidence interval −3.7 to 89.4), with concussion being the most common (33%). An overall injury rate of 2.0 injuries per 1000 hours of boxing was calculated.

Conclusion:The high exposure experienced by the boxers (as a result of considerable training time) indicated that boxing has acute injury rates comparable to, and often lower than, those found in other contact and non-contact sports. Further, acute injuries during training appear to be less common and severe than those sustained in bouts.
ICAM-1 expression in adipose tissue: effects of diet-induced obesity in mice
Authors: Brake Danett K. , Smith E. O'Brian , Mersmann Harry , Smith C. Wayne , Robker Rebecca L.
Published: June 2006

Obesity has been linked to cardiovascular disease, hypertension, diabetes and the metabolic syndrome, with elevated markers of systemic inflammation. Intercellular adhesion molecule-1 (ICAM-1) is a transmembrane adhesion molecule involved in leukocyte migration to sites of inflammation. In human obesity, elevated expression of the soluble form of ICAM-1 (sICAM-1) is positively correlated with abdominal fat deposition. Increases in adiposity have also been correlated with macrophage infiltration into adipose tissue. Here we investigate adipose tissue production and transcriptional regulation of ICAM-1 in a mouse model of dietary obesity. After feeding mice a high-fat diet, ICAM-1 expression in serum and adipose tissue was analyzed by ELISA, Northern blotting, real-time quantitative PCR, and flow cytometry. After 6 mo on the high-fat diet, sICAM-1 levels significantly correlated with body weight and abdominal fat mass. ICAM-1 mRNA was expressed in adipose tissue of mice, with significantly higher levels in males than females. After only 3 wk, there were adipose tissue-specific increases in mRNAs for ICAM-1, IL-6, and monocyte chemoattractant protein-1 (MCP-1) in male mice. Analysis of the stromal-vascular fraction of male adipose tissue revealed CD11b-negative cells with increased surface ICAM-1 and CD34. We also found two populations of F4/80+, CD11b+, ICAM-1+ cells, one of which also expressed CD14 and CD11c and was increased in response to a high-fat diet. These results indicate that within 3 wk on a high-fat diet, male mice exhibited significant increases in pro-inflammatory factors and immune cell infiltration in adipose tissue that may represent links between obesity and its associated inflammatory complications.
Ouabain induces cell proliferation through calcium-dependent phosphorylation of Akt (protein kinase B) in opossum kidney proximal tubule cells
Authors: Khundmiri Syed J. , Metzler Melissa A. , Ameen Mohamed , Amin Vishal , Rane Madhavi J. , Delamere Nicholas A.
Published: June 2006

Cardiotonic glycosides, like ouabain, inhibit Na+-K+-ATPase. Recent evidence suggests that low molar concentrations of ouabain alter cell growth. Studies were conducted to examine the effect of ouabain on Akt phosphorylation and rate of cell proliferation in opossum kidney (OK) proximal tubule cells. Cells exposed to 10 nM ouabain displayed increased Akt Ser473 phosphorylation, as evidenced by an increase in phospho-Akt Ser473 band density. Ouabain-stimulated Akt Ser473 phosphorylation was inhibited by pretreatment with phosphatidylinositol 3-kinase (PI3K) inhibitors (LY294002 and wortmannin), a PLC inhibitor (edelfosine), and an Akt inhibitor. Moreover, ouabain-mediated Akt Ser473 phosphorylation was suppressed by reduction of extracellular calcium (EGTA) or when intracellular calcium was buffered by BAPTA-AM. An inhibitor of calcium store release (TMB-8) and an inhibitor of calcium entry via store-operated calcium channels ( SKF96365 ) also suppressed ouabain-mediated Akt Ser473 phosphorylation. In fura-2 AM-loaded cells, 10 nM ouabain increased capacitative calcium entry (CCE). Ouabain at 10 nM did not significantly alter baseline cytoplasmic calcium concentration in control cells. However, treatment with 10 nM ouabain caused a significantly higher ATP-mediated calcium store release. After 24 h, 10 nM ouabain increased the rate of cell proliferation. The Akt inhibitor, BAPTA-AM, SKF96365 , and cyclopiazonic acid suppressed the increase in the rate of cell proliferation caused by 10 nM ouabain. Ouabain at 10 nM caused a detectable increase in 86Rb uptake but did not significantly alter Na+-K+-ATPase (ouabain-sensitive pNPPase) activity in crude membranes or cell sodium content. Taken together, the results point to a role for CCE and Akt phosphorylation, in response to low concentrations of ouabain, that increase the rate of cell proliferation without inhibiting Na+-K+-ATPase-mediated ion transport.
Contribution of Persistent Na+Current and M-Type K+Current to Somatic Bursting in CA1 Pyramidal Cells: Combined Experimental and Modeling Study
Authors: Golomb David , Yue Cuiyong , Yaari Yoel
Published: June 2006

The intrinsic firing modes of adult CA1 pyramidal cells vary along a continuum of “burstiness” from regular firing to rhythmic bursting, depending on the ionic composition of the extracellular milieu. Burstiness is low in neurons exposed to a normal extracellular Ca2+concentration ([Ca2+]o), but is markedly enhanced by lowering [Ca2+]o, although not by blocking Ca2+and Ca2+-activated K+currents. We show, using intracellular recordings, that burstiness in low [Ca2+]opersists even after truncating the apical dendrites, suggesting that bursts are generated by an interplay of membrane currents at or near the soma. To study the mechanisms of bursting, we have constructed a conductance-based, one-compartment model of CA1 pyramidal neurons. In this neuron model, reduced [Ca2+]ois simulated by negatively shifting the activation curve of the persistent Na+current ( INaP) as indicated by recent experimental results. The neuron model accounts, with different parameter sets, for the diversity of firing patterns observed experimentally in both zero and normal [Ca2+]o. Increasing INaPin the neuron model induces bursting and increases the number of spikes within a burst but is neither necessary nor sufficient for bursting. We show, using fast-slow analysis and bifurcation theory, that the M-type K+current ( IM) allows bursting by shifting neuronal behavior between a silent and a tonically active state provided the kinetics of the spike generating currents are sufficiently, although not extremely, fast. We suggest that bursting in CA1 pyramidal cells can be explained by a single compartment “square bursting” mechanism with one slow variable, the activation of IM.
Phase Locking of Auditory-Nerve Fibers to the Envelopes of High-Frequency Sounds: Implications for Sound Localization
Authors: Dreyer Anna , Delgutte Bertrand
Published: June 2006

Although listeners are sensitive to interaural time differences (ITDs) in the envelope of high-frequency sounds, both ITD discrimination performance and the extent of lateralization are poorer for high-frequency sinusoidally amplitude-modulated (SAM) tones than for low-frequency pure tones. Psychophysical studies have shown that ITD discrimination at high frequencies can be improved by using novel transposed-tone stimuli, formed by modulating a high-frequency carrier by a half-wave–rectified sinusoid. Transposed tones are designed to produce the same temporal discharge patterns in high-characteristic frequency (CF) neurons as occur in low-CF neurons for pure-tone stimuli. To directly test this hypothesis, we compared responses of auditory-nerve fibers in anesthetized cats to pure tones, SAM tones, and transposed tones. Phase locking was characterized using both the synchronization index and autocorrelograms. With both measures, phase locking was better for transposed tones than for SAM tones, consistent with the rationale for using transposed tones. However, phase locking to transposed tones and that to pure tones were comparable only when all three conditions were met: stimulus levels near thresholds, low modulation frequencies (<250 Hz), and low spontaneous discharge rates. In particular, phase locking to both SAM tones and transposed tones substantially degraded with increasing stimulus level, while remaining more stable for pure tones. These results suggest caution in assuming a close similarity between temporal patterns of peripheral activity produced by transposed tones and pure tones in both psychophysical studies and neurophysiological studies of central neurons.
Inhibition of Nav1.7 and Nav1.4 Sodium Channels by Trifluoperazine Involves the Local Anesthetic Receptor
Authors: Sheets Patrick L. , Gerner Peter , Wang Chi-Fei , Wang Sho-Ya , Wang Ging Kuo , Cummins Theodore R.
Published: June 2006

The calmodulin (CaM) inhibitor trifluoperazine (TFP) can produce analgesia when given intrathecally to rats; however, the mechanism is not known. We asked whether TFP could modulate the Nav1.7 sodium channel, which is highly expressed in the peripheral nervous system and plays an important role in nociception. We show that 500 nM and 2 μM TFP induce major decreases in Nav1.7 and Nav1.4 current amplitudes and that 2 μM TFP causes hyperpolarizing shifts in the steady-state inactivation of Nav1.7 and Nav1.4. CaM can bind to the C-termini of voltage-gated sodium channels and modulate their functional properties; therefore we investigated if TFP modulation of sodium channels was due to CaM inhibition. However, the TFP inhibition was not replicated by whole cell dialysis of a calmodulin inhibitory peptide, indicating that major effects of TFP do not involve a disruption of CaM-channel interactions. Rather, our data show that TFP inhibition is state dependent and that the majority of the TFP inhibition depends on specific amino-acid residues in the local anesthetic receptor site in sodium channels. TFP was also effective in vivo in causing motor and sensory blockade after subfascial injection to the rat sciatic nerve. The state-dependent block of Nav1.7 channels with nanomolar concentrations of TFP raises the possibility that TFP, or TFP analogues, might be useful for regional anesthesia and pain management and could be more potent than traditional local anesthetics.
Multiple Time Scales of Temporal Response in Pyramidal and Fast Spiking Cortical Neurons
Authors: La Camera Giancarlo , Rauch Alexander , Thurbon David , Lüscher Hans-R. , Senn Walter , Fusi Stefano
Published: June 2006

Neural dynamic processes correlated over several time scales are found in vivo, in stimulus-evoked as well as spontaneous activity, and are thought to affect the way sensory stimulation is processed. Despite their potential computational consequences, a systematic description of the presence of multiple time scales in single cortical neurons is lacking. In this study, we injected fast spiking and pyramidal (PYR) neurons in vitro with long-lasting episodes of step-like and noisy, in-vivo-like current. Several processes shaped the time course of the instantaneous spike frequency, which could be reduced to a small number (1–4) of phenomenological mechanisms, either reducing (adapting) or increasing (facilitating) the neuron's firing rate over time. The different adaptation/facilitation processes cover a wide range of time scales, ranging from initial adaptation (<10 ms, PYR neurons only), to fast adaptation (<300 ms), early facilitation (0.5–1 s, PYR only), and slow (or late) adaptation (order of seconds). These processes are characterized by broad distributions of their magnitudes and time constants across cells, showing that multiple time scales are at play in cortical neurons, even in response to stationary stimuli and in the presence of input fluctuations. These processes might be part of a cascade of processes responsible for the power-law behavior of adaptation observed in several preparations, and may have far-reaching computational consequences that have been recently described.
Institutional Effects on the IT Outsourcing Market: Analysing Clients, Suppliers and Staff Transfer in Germany and the UK
Authors: Grimshaw Damian , Miozzo Marcela
Published: June 2006

Drawing on empirical evidence in Germany and the UK, this article examines the institutional effects on a fast-growing area of knowledge-intensive business services — IT outsourcing. This is an important area for research since the IT outsourcing market provides many organizations with an important specialized production input and is characterized by complex inter-organizational relations. By exploring institutional influences in the context of IT outsourcing, the research extends earlier studies on how client–supplier relations shape markets for business services. It also contributes to varieties of capitalism debates by highlighting heterogeneous institutional effects within countries and common systemic trends (involving powerful multinational IT firms) in the development of the market for IT outsourcing. Comparative analysis of 13 IT outsourcing contracts in Germany and the UK, focusing on the organizational practices of client organizations and IT firms, illuminated institutional effects within the organizational setting. Analysis of industrylevel data shows that the diverse institutional contexts of Germany and the UK provided an equally favourable basis for growth in the IT outsourcing market, despite its apparent deregulatory bias. But significant institutional effects were observed, specifically related to: the role of deliberative institutions (especially works councils); and institutions governing technical standards and contracting rules. Strong deliberative institutions in Germany facilitated market growth since transactions involved distributive dilemmas, particularly related to staff transfer. Also, while institutions shaped technical and contractual expertise of client managers, they were not deterministic. Instead, they interacted with characteristics of the IT outsourcing market, namely: heterogeneous client practices to improve absorptive capacity; public vs. private contracting experience; and power relations between client and IT firm in their use of market discipline.
Reshaping the Hourglass? The Environmental Movement and Civil Society Development in the Russian Federation
Authors: Crotty Jo
Published: June 2006

Rose's and Mishler and Rose's ‘hourglass’ construction of post-Soviet Russian society illustrates that the civil space traditionally occupied by advocacy and community groups continues to be constricted. Such groups fail to successfully bridge the space between the individual and the state, thereby holding the fledgling Russian democracy to account. In this paper, to shed light on reasons for the continuing constriction of Russian civil space, the behavior of the environmental movement in one Russian region — Samara Oblast — is observed through the lens of social capital. By utilizing Adler and Kwon's schema for assessing the benefits and risks arising from social capital stocks possessed by collectives, it will illustrate that the Russian environmental movement is inward looking and parochial; built on pre-existing friendships or elite connections; and uninterested in forming a mass movement or actively engaging with the Russian public. Moreover, rather than being situated within the constricted civil space of Russian society, the majority of groups within the Samara environmental movement are themselves situated firmly in either half of the hourglass. Groups within each half successfully span gaps between each other, but no activity is undertaken to bridge or reshape the constricted space between the halves.
The Problems of Embeddedness: Knowledge Transfer, Coordination and Reuse in Information Systems
Authors: Hsiao Ruey-Lin , Tsai Stephen Dun-Hou , Lee Ching-Fang
Published: June 2006

This research examines the knowledge management challenge underlying technology use. It proposes to examine the key question: how can knowledge management problems and technology adoption difficulties be analysed through experts' practices embedded in their work contexts? The problems of knowledge transfer, coordination and reuse are investigated by examining experts' practices and work contexts. The inquiry is grounded in a qualitative case study of a knowledge management system designed to support maintenance work performed by two groups of engineers in a semiconductor-fabrication equipment company. The findings illustrate two contrasting outcomes: the equipment engineers found the system to be useful; the field engineers considered it to be irrelevant to their work contexts. An analysis of the fabrication process (the technical context), engineers' professional communities (the social context), and the pace of product/process innovation (the innovative context) helps us to understand the main problems underlying knowledge transfer, coordination and reuse. Significantly, we propose a specific definition of knowledge and suggest a way to examine practices and work contexts that can help to uncover new difficulties in knowledge management system adoption. The theoretical and practical implications of the study are discussed.
Pendent Polyimides using Mellitic Acid Dianhydride. I. An Atomic Oxygen-resistant, Pendent 4,4′-ODA/PMDA/MADA Co-polyimide Containing Zirconium
Authors: Wagner Shawn , Dai Huixiong , Stapleton Russell A. , Illingsworth Marvin L. , Siochi Emilie J.
Published: June 2006

The goal of this research is to increase the metal-organic concentration in Kapton-like polyimides (PIs) to achieve increased atomic oxygen (AO) resistance while retaining desirable film properties. Co-polyamic acid (PAA) precursors were prepared using a novel polymer building block, mellitic acid dianhydride (MADA), to provide sites for pendent group attachment. Attachment of an amino group-functionalized zirconium complex to the co-PAA precursors was facilitated by a stoichiometric amount of dicyclohexylcarbodiimide. The viscous solutions which resulted were characterized by thin layer chromatography (TLC), viscosity, and gel permeation chromatography (GPC), or treated with excess poor solvent to precipitate powder samples, or cast onto glass slides and heated to produce imidized films. Powder samples were dissolved in deuterated solvent for proton nuclear magnetic resonance analysis, or characterized by thermogravimetric analysis and differential scanning calorimetry. Film samples were characterized by Fourier transform infrared and by scanning electron microscopy (SEM) before and after exposure to atomic oxygen in a plasma asher. The spectroscopic data are consistent with the expected amic acid and imide, pendent and non-pendent structures. TLC, viscosity and GPC results confirm the polymeric nature of the pendent and non-pendent co-PAA precursors, with inherent viscosities (<0)of 0.76 and 0.65 and weight average molecular weights (Mw) estimated to be 61 000 and 138 000 Dalton, respectively. As expected, visual and SEM inspections of pendent and non-pendent co-PI films reveal extensive surface roughening upon exposure to AO, with the former developing a white surface layer known from model compound studies to be predominantly zirconium dioxide. Additional reports describing the effects of polymer structure and pendent group concentration on film properties and AO resistance are in preparation.
Water as Solvent in Polyimide Synthesis III: Towards the Synthesis of Polyamideimides
Authors: Chiefari John , Dao Buu , Groth Andrew M. , Hodgkin Jonathan H.
Published: June 2006

Four different approaches to the synthesis of polyamideimides, which employ aqueous imidization, were studied in order to assess the viability of their preparation in water. Building on previous studies of synthesizing polyimides in water both one- and two-step methods were explored. The first direct method for polyamideimide synthesis forms both the amide and imide linkages simultaneously and is limited to appropriately activated diamine monomers. The second direct method uses commercially sourced diaminobenzanilide with standard tetracarboxylic acids in an imidization step to give the polyamideimide. This method, demonstrates the viability of using amide-containing diamines in a polyimidization step to synthesize the desired polymer. The third and fourth methods are both two-step processes and use aqueous imidization to produce imide-containing monomers with either amine or carboxylic acid terminal functionality. This is followed by standard amidation to produce high-quality polyamideimides.
Tuberculosis outbreak among students in a boarding school
Authors: Stein-Zamir C. , Volovik I. , Rishpon S. , Atamna A. , Lavy A. , Weiler-Ravell D.
Published: June 2006

Tuberculosis (TB) outbreaks present a public health challenge. Six cases of active TB emerged in a boarding school in Israel during 1 yr. An epidemiological outbreak investigation was performed, followed by implementation of control measures.

The investigation included interviews, tuberculin skin test (TST) and chest radiographs of the students. Close contact (n = 155) was defined as being in the same class or dormitory with a patient. Remote contact (n = 246) was defined as being in the school.

An epidemiological association was detected among five of the cases and a distinct pattern was found in molecular analysis. TST was performed in 398 (99.2%) students. Repeated (two-step) TST was applied to the close contacts. The degree of contact, country of origin and previous bacille Calmette–Guérin vaccination were significantly associated with TST reactions. Preventive directly observed therapy was completed by 157 (91.3%) students. During 5 yrs follow-up, no additional cases emerged.

While investigating a tuberculosis outbreak, the definition of degree of contact is a significant predictor for detecting positive tuberculin test. Immigration from an endemic country, as well as previous bacille Calmette–Guérin vaccination have a major effect on tuberculin skin-test results. The directly observed therapy approach was found to be successful in preventing further morbidity.
How is difficult asthma managed?
Authors: Roberts N. J. , Robinson D. S. , Partridge M. R.
Published: June 2006

Most patients with asthma can be easily treated. Some have difficult asthma; in some because the diagnosis is erroneous, in others because of comorbidity or noncompliance. A European Respiratory Society Task Force has called for an integrated approach for these patients, and positive results have been reported using protocols. In the UK, there is no overall understanding of the size of this problem, or how these patients are managed.

A postal survey of 683 consultant members of the British Thoracic Society designed to elicit respondents' views on how they would manage four clinical scenarios was conducted.

There was a 50.4% response rate. Few reported a uniform approach to the investigation of such patients. The availability of allied healthcare professionals was variable. The 21 consultant respiratory physicans, reporting a special interest in difficult asthma, were significantly more likely to objectively assess compliance, perform skin-prick tests and to utilise a liaison psychiatrist than those without an expressed special interest in asthma. Many reported difficulty in accessing psychologists, liaison psychiatrists and social workers. Approaches to the diagnosis and management of “vocal cord dysfunction” were variable.

The results of this postal survey of specialist thoracic physicians in the UK suggest that a protocol for difficult asthma is not in widespread use and that access to necessary allied healthcare professionals is not uniform. Pulmonologists with a declared special interest in difficult asthma may have configured their services and approaches more in line with that proposed by the European Respiratory Society Task Force.