bluuebunny/crossref_metadata_2025 huggingface dataset:
The African Swine Fever Virus Virion Membrane Protein pE248R Is Required for Virus Infectivity and an Early Postentry Event
Authors: Rodríguez Irene , Nogal María L. , Redrejo-Rodríguez Modesto , Bustos María J. , Salas María L.
Published: October 2009

The African swine fever virus (ASFV) protein pE248R, encoded by the gene E248R, is a late structural component of the virus particle. The protein contains intramolecular disulfide bonds and has been previously identified as a substrate of the ASFV-encoded redox system. Its amino acid sequence contains a putative myristoylation site and a hydrophobic transmembrane region near its carboxy terminus. We show here that the protein pE248R is myristoylated during infection and associates with the membrane fraction in infected cells, behaving as an integral membrane protein. Furthermore, the protein localizes at the inner envelope of the virus particles in the cytoplasmic factories. The function of the protein pE248R in ASFV replication was investigated by using a recombinant virus that inducibly expresses the gene E248R. Under repressive conditions, the ASFV polyproteins pp220 and pp62 are normally processed and virus particles with morphology indistinguishable from that of those produced in a wild-type infection or under permissive conditions are generated. Moreover, the mutant virus particles can exit the cell as does the parental virus. However, the infectivity of the pE248R-deficient virions was reduced at least 100-fold. An investigation of the defect of the mutant virus indicated that neither virus binding nor internalization was affected by the absence of the protein pE248R, but a cytopathic effect was not induced and early and late gene expression was impaired, indicating that the protein is required for some early postentry event.
The Polymerase Acidic Protein Gene of Influenza A Virus Contributes to Pathogenicity in a Mouse Model
Authors: Song Min-Suk , Pascua Philippe Noriel Q. , Lee Jun Han , Baek Yun Hee , Lee Ok-Jun , Kim Chul-Joong , Kim Hyunggee , Webby Richard J. , Webster Robert G. , Choi Young Ki
Published: October 2009

Adaptation of influenza A viruses to a new host species usually involves the mutation of one or more of the eight viral gene segments, and the molecular basis for host range restriction is still poorly understood. To investigate the molecular changes that occur during adaptation of a low-pathogenic avian influenza virus subtype commonly isolated from migratory birds to a mammalian host, we serially passaged the avirulent wild-bird H5N2 strain A/Aquatic bird/Korea/W81/05 (W81) in the lungs of mice. The resulting mouse-adapted strain (ma81) was highly virulent (50% mouse lethal dose = 2.6 log
10
50% tissue culture infective dose) and highly lethal. Nonconserved mutations were observed in six viral genes (those for PB2, PB1, PA, HA, NA, and M). Reverse genetic experiments substituting viral genes and mutations demonstrated that the PA gene was a determinant of the enhanced virulence in mice and that a Thr-to-Iso substitution at position 97 of PA played a key role. In growth kinetics studies, ma81 showed enhanced replication in mammalian but not avian cell lines; the PA
97I
mutation in strain W81 increased its replicative fitness in mice but not in chickens. The high virulence associated with the PA
97I
mutation in mice corresponded to considerably enhanced polymerase activity in mammalian cells. Furthermore, this characteristic mutation is not conserved among avian influenza viruses but is prevalent among mouse-adapted strains, indicating a host-dependent mutation. To our knowledge, this is the first study that the isoleucine residue at position 97 in PA plays a key role in enhanced virulence in mice and is implicated in the adaptation of avian influenza viruses to mammalian hosts.
Role of ORF74-Encoded Viral G Protein-Coupled Receptor in Human Herpesvirus 8 Lytic Replication
Authors: Sandford Gordon , Choi Young Bong , Nicholas John
Published: October 2009

The human herpesvirus 8 (HHV-8) viral G protein-coupled receptor (vGPCR) has been implicated in virus-associated disease pathogenesis due principally to its ability to induce the production of angiogenic cytokines involved in this process. However, the role of the vGPCR in normal virus biology is understudied and remains unknown. Here we provide evidence from vGPCR gene knockout and depletion experiments that vGPCR is a positive regulator of HHV-8 productive replication and, through experimental utilization of Gα-coupling variants of vGPCR, that signaling via Gα
q
activation and targeted mitogen-activated protein kinase pathways is of particular relevance to this activity.
Dengue Virus Infection Induces Upregulation of GRP78, Which Acts To Chaperone Viral Antigen Production
Authors: Wati S. , Soo M.-L. , Zilm P. , Li P. , Paton A. W. , Burrell C. J. , Beard M. , Carr J. M.
Published: October 2009

Dengue virus (DENV) pathogenesis is related to the host responses to viral infection within target cells, and therefore, this study assessed intracellular changes in host proteins following DENV infection. Two-dimensional gel electrophoresis and mass spectrometry identified upregulation of the host endoplasmic reticulum (ER) chaperone GRP78 in K562 cells following DENV infection, in the absence of virus-induced cell death. Upregulation of GRP78 in DENV-infected cells was confirmed by immunostaining and confocal microscopy and by Western blot analysis and was also observed in DENV-infected primary monocyte-derived macrophages, a natural target cell type for DENV infection. GRP78 was upregulated in both DENV antigen-positive and -negative cells in the DENV-infected culture, suggesting a bystander effect, with the highest GRP78 levels coincident with high-level DENV antigen production and infectious-virus release. Transfection of target cells to express GRP78 prior to DENV challenge did not affect subsequent DENV infection, but cleavage of GRP78 with the SubAB toxin, during an established DENV infection, yielded a 10- to 100-fold decrease in infectious-virus release, loss of intracellular DENV particles, and a dramatic decrease in intracellular DENV antigen. However, DENV RNA levels were unchanged, indicating normal DENV RNA replication but altered DENV antigen levels in the absence of GRP78. Thus, GRP78 is upregulated by DENV infection and is necessary for DENV antigen production and/or accumulation. This may be a common requirement for viruses such as flaviviruses that depend heavily on the ER for coordinated protein production and processing.
CORRELATED LINGUISTIC INFORMATION AGGREGATION
Authors: XU Z. S.
Published: October 2009

Linguistic information aggregation has received great attention from researchers, and a variety of operators have been developed for aggregating linguistic information. All the existing linguistic information aggregation operators only consider the situations where all the aggregated linguistic arguments are independent, i.e., they only consider the addition of the importance of individual linguistic arguments, however, in some actual situations, the considered linguistic arguments may be correlative. In this paper, we focus on this issue. Motivated by the idea of the well-known Choquet integrals,1 we propose two new linguistic information aggregation operators called the linguistic correlated averaging operator and linguistic correlated geometric operator. In the special cases where the aggregated linguistic arguments are independent, the linguistic correlated averaging operator can be reduced to a variety of traditional linguistic averaging aggregation operators; while the linguistic correlated geometric operator can be reduced to a variety of the traditional linguistic geometric aggregation operators. Furthermore, we extend the above results to accommodate uncertain linguistic environments, and illustrate them with a practical problem.
MANAGING TARGET THE CASH BALANCE IN CONSTRUCTION FIRMS USING A FUZZY REGRESSION APPROACH
Authors: CHEN CHENG-WU , WANG MORRIS H. L. , LIN JENG-WEN
Published: October 2009

Construction firms that work on a contractual basis are generally more concerned with short-term rather than long-term financial strategies. The main focus in short-term financial strategies is on working capital management (WCM). Cash management is a major factor for achieving good liquidity and profitability. In this study we take into consideration the cash component of working capital management based on the target cash balance. We develop a practical model that should allow Taiwan construction firms to utilize the currently available cash and assets at any point in time in the most rational way. To help understand the issues involved, we first introduce a model developed by Miller and Orr. The relationship between project duration and progress towards completion is most effectively represented in practical construction management by the S-curve. Thus, in this study we plot the fuzzy S-curve regression based on the Takagi-Sugeno (T-S) fuzzy model. The practicality of the model is demonstrated using project cash flow and progress payment records from a sample project. The data are obtained from the Taipei City Government's Department of Rapid Transit Systems. Some tentative conclusions concerning the model are also given.
ADAPTIVE FUZZY SLIDING MODE CONTROL FOR SEISMICALLY EXCITED BRIDGES WITH LEAD RUBBER BEARING ISOLATION
Authors: CHEN CHENG-WU , YEH KEN , LIU KEVIN FONG-REY
Published: October 2009

This study examines the feasibility of applying adaptive fuzzy sliding mode control (AFSMC) strategies to reduce the dynamic responses of bridges constructed using a lead rubber bearing (LRB) isolation hybrid protective system. Recently developed control devices for civil engineering structures, including hybrid systems and semi-active systems, have been found to have inherent nonlinear properties. It is thus necessary to develop non-linear control methods to deal with such properties. Generally, controller fuzziness increases the robustness of the control system to counter uncertain system parameters and input excitation, and the non-linearity of the control rule increases the effectiveness of the controller relative to linear controllers. Adaptive fuzzy sliding mode control (AFSMC) is a combination of sliding mode control (SMC) and fuzzy control. The performance and robustness of these proposed control methods are all verified by numerical simulation. The results demonstrate the viability of the presented methods. The attractive control strategy derived there-from is applied to seismically excited bridges using LRB isolation.
DEVELOPMENT OF A NEURO FUZZY MODEL FOR NOISE PREDICTION IN OPENCAST MINES
Authors: NANDA SANTOSH KUMAR , TRIPATHY DEBI PRASAD , PATRA SARAT KUMAR
Published: October 2009

The need of developing appropriate noise prediction models for finding out the accurate status of noise levels (>90 dBA) generated from various opencast mining machineries is overdue. The measured sound pressure levels (SPL) of equipments are not accurate due to instrumental error, attenuation due to geometrical aberration, atmospheric attenuation etc. Some of the popular noise prediction models e.g. VDI and ENM have been applied in mining and allied industries. Among these models, VDI2714 is simple and less complex model. In this paper, a neuro-fuzzy model is proposed to predict the machinery noise in an opencast coal mine. The proposed model is trained with VDI2714 and the model output is seen very closely to matching with VDI2714 output. The model proposed has a mean square error of 2.73%. This model takes CPU time of nearly 0.0625 sec where as it takes 0.5 sec for VDI2714 i.e. approximately twelve times faster.
MODELING OF COGNITIVE STRUCTURE OF UNCERTAIN SCIENTIFIC CONCEPTS USING FUZZY-ROUGH SETS AND INTUITIONISTIC FUZZY SETS: EXAMPLE OF THE LIFE CONCEPT
Authors: YOREK NURETTIN , NARLI SERKAN
Published: October 2009

In this study, using fuzzy-rough set and intuitionistic fuzzy set approaches, we propose a cognitive structural model for the concept of life for which a certain definition can not be made because of scientific uncertainty as well as moral, legal, and theological aspects. Total 191 first-year students from seven different high schools in a large western city in Turkey participated in the study. An open-ended conceptual understanding (CULC) test, developed by the researcher, was used for data collection. Semi-structured interviews were carried out with 14 students and their biology teachers to clarify ambiguous points in students' responses to the CULC test. The results of analyses indicated that students constructed the concept of life by associating it predominantly with 'human'. Motion appeared as the most frequently associated term with the concept of life. The results suggest that the life concept has been constructed using animistic-anthropocentric cognitive schemes. In the next step, we evaluated the data obtained from the CULC test using the fuzzy-rough set and intuitionistic fuzzy set theories. Consequently, we propose an 'animistic-anthropocentric structural model' about cognitive construction of the concept of life.
INTERVAL METHODS IN KNOWLEDGE REPRESENTATION
Authors: Kreinovich Vladik
Published: October 2009

This section is maintained by Vladik Kreinovich. Please send your abstracts (or copies of papers that you want to see reviewed here) to vladik@utep.edu, or by regular mail to: Vladik Kreinovich, Department of Computer Science, University of Texas at El Paso, El Paso, TX 79968, USA.
Kbg and Kv1.3 channels mediate potassium efflux in the early phase of apoptosis in Jurkat T lymphocytes
Authors: Valencia-Cruz Georgina , Shabala Lana , Delgado-Enciso Ivan , Shabala Sergey , Bonales-Alatorre Edgar , Pottosin Igor I. , Dobrovinskaya Oxana R.
Published: October 2009

Microelectrode ion flux estimation (MIFE) and patch-clamp techniques were combined for noninvasive K+ flux measurements and recording of activities of the dominant K+ channels in the early phases of apoptosis in Jurkat cells. Staurosporine (STS, 1 μM) evoked rapid (peaking around 15 min) transient K+ efflux, which then gradually decreased. This transient K+ efflux occurred concurrently with the transient increase of the K+ background (Kbg) TWIK-related spinal cord K+ channel-like current density, followed by a drastic decrease and concomitant membrane depolarization. The Kv1.3 current density remained almost constant. Kv1.3 activation was not altered by STS, whereas the inactivation was shifted to more positive potentials. Contribution of Kbg and Kv1.3 channels to the transient and posttransient STS-induced K+ efflux components, respectively, was confirmed by the effects of bupivacaine, predominantly blocking Kbg current, and the Kv1.3-specific blocker margatoxin. Channel-mediated K+ efflux provoked a substantial cellular shrinkage and affected the activation of caspases.
FAPP2 is required for aquaporin-2 apical sorting at trans-Golgi network in polarized MDCK cells
Authors: Yui Naofumi , Okutsu Rie , Sohara Eisei , Rai Tatemitsu , Ohta Akihito , Noda Yumi , Sasaki Sei , Uchida Shinichi
Published: October 2009

FAPP2 is an adaptor protein of phosphatidylinositol-4-phosphate and is involved in the transport of some apical cargos from the trans-Golgi network (TGN). To investigate whether the regulated apical transport of aquaporin-2 (AQP2) is involved in the FAPP2-dependent apical protein-sorting machinery, we measured apical sorting of AQP2 in Madin-Darby canine kidney (MDCK) cells with or without FAPP2 knockdown. We established MDCK cell lines that stably express rat AQP2 without any tag sequence. Then, FAPP2-deficient stable cell lines were established from the AQP2-expressing cell lines by a retrovirus-mediated RNA interference system. In the established cell lines, AQP2 was detected in both apical and basolateral membranes. Forskolin increased only the apical localization of AQP2, which was not affected by basolateral treatment with 0.5% tannic acid, indicating that the forskolin-induced apical transport of AQP2 did not include the transcytotic pathway from basolateral to apical membranes but is a direct transport from TGN to the apical membranes. Using these cell lines, we tested the effect of FAPP2 knockdown on the polarized AQP2 transport to plasma membranes and found that the forskolin-induced apical transport of AQP2 was completely abolished by FAPP2 knockdown. By contrast, the basolateral localization of AQP2 was not affected by FAPP2 knockdown. AQP2 phosphorylation by forskolin was also impaired in FAPP2 knockdown MDCK cells. These results suggest that FAPP2 is necessary to generate AQP2-bearing vesicles at trans-Golgi that will undergo phosphorylation by PKA in subapical regions.
Protein kinase D mediates synergistic expression of COX-2 induced by TNF-α and bradykinin in human colonic myofibroblasts
Authors: Yoo James , Chung Christine , Slice Lee , Sinnett-Smith James , Rozengurt Enrique
Published: October 2009

Myofibroblasts have recently been identified as major mediators of tumor necrosis factor-α (TNF-α)-associated colitis, but the precise mechanism(s) involved remains incompletely understood. In particular, the possibility that TNF-α signaling cross talks with other proinflammatory mediators, including bradykinin (BK), has not been examined in these cells. Here we show that treatment of 18Co cells, a model of human colonic myofibroblasts, with BK and TNF-α induced striking synergistic COX-2 protein expression that was paralleled by increases in the levels of transcripts encoding COX-2 and microsomal prostaglandin E synthase 1 (mPGES-1) and by the production of PGE2. COX-2 expression in 18Co cells treated with BK and TNF-α was prevented by the B2 BK receptor antagonist HOE-140, the preferential protein kinase C (PKC) inhibitors Ro31-8220 and GF-109203X, and Gö-6976, an inhibitor of conventional PKCs and protein kinase D (PKD). In a parallel fashion, TNF-α, while having no detectable effect on the activation of PKD when added alone, augmented PKD activation induced by BK, as measured by PKD phosphorylation at its activation loop (Ser744) and autophosphorylation site (Ser916). BK-induced PKD activation was also inhibited by HOE-140, Ro31-8220, and Gö-6976. Transfection of 18Co cells with small interfering RNA targeting PKD completely inhibited the synergistic increase in COX-2 protein in response to BK and TNF-α, demonstrating, for the first time, a critical role of PKD in the pathways leading to synergistic expression of COX-2. Our results imply that cross talk between TNF-α and BK amplifies a PKD phosphorylation cascade that mediates synergistic COX-2 expression in colonic myofibroblasts. It is plausible that PKD increases COX-2 expression in colonic myofibroblasts to promote an inflammatory microenvironment that supports tumor growth.
mTOR regulates skeletal muscle regeneration in vivo through kinase-dependent and kinase-independent mechanisms
Authors: Ge Yejing , Wu Ai-Luen , Warnes Christine , Liu Jianming , Zhang Chongben , Kawasome Hideki , Terada Naohiro , Boppart Marni D. , Schoenherr Christopher J. , Chen Jie
Published: October 2009

Rapamycin-sensitive signaling is required for skeletal muscle differentiation and remodeling. In cultured myoblasts, the mammalian target of rapamycin (mTOR) has been reported to regulate differentiation at different stages through distinct mechanisms, including one that is independent of mTOR kinase activity. However, the kinase-independent function of mTOR remains controversial, and no in vivo studies have examined those mTOR myogenic mechanisms previously identified in vitro. In this study, we find that rapamycin impairs injury-induced muscle regeneration. To validate the role of mTOR with genetic evidence and to probe the mechanism of mTOR function, we have generated and characterized transgenic mice expressing two mutants of mTOR under the control of human skeletal actin (HSA) promoter: rapamycin-resistant (RR) and RR/kinase-inactive (RR/KI). Our results show that muscle regeneration in rapamycin-administered mice is restored by RR-mTOR expression. In the RR/KI-mTOR mice, nascent myofiber formation during the early phase of regeneration proceeds in the presence of rapamycin, but growth of the regenerating myofibers is blocked by rapamycin. Igf2 mRNA levels increase drastically during early regeneration, which is sensitive to rapamycin in wild-type muscles but partially resistant to rapamycin in both RR- and RR/KI-mTOR muscles, consistent with mTOR regulation of Igf2 expression in a kinase-independent manner. Furthermore, systemic ablation of S6K1, a target of mTOR kinase, results in impaired muscle growth but normal nascent myofiber formation during regeneration. Therefore, mTOR regulates muscle regeneration through kinase-independent and kinase-dependent mechanisms at the stages of nascent myofiber formation and myofiber growth, respectively.
Maitotoxin converts the plasmalemmal Ca2+pump into a Ca2+-permeable nonselective cation channel
Authors: Sinkins William G. , Estacion Mark , Prasad Vikram , Goel Monu , Shull Gary E. , Kunze Diana L. , Schilling William P.
Published: October 2009

Maitotoxin (MTX) activates Ca2+-permeable nonselective cation channels and causes a dramatic increase in cytosolic free Ca2+concentration ([Ca2+]i) in every cell examined to date, but the molecular identity of the channels involved remains unknown. A clue came from studies of a structurally related marine toxin called palytoxin (PTX). PTX binds to the plasmalemmal Na+-K+-ATPase (NKA) and converts the Na+pump into a nonselective cation channel. Given the high permeability of the MTX channel for Ca2+, we considered the possibility that MTX may bind to the plasmalemmal Ca2+-ATPase (PMCA) pump, and like PTX, convert the pump into a channel. To test this hypothesis, the PMCA was overexpressed in Spodoptera frugiperda (Sf9) insect cells and in human embryonic kidneys (HEK) 293 cells. In both cell types, enhanced expression of the PMCA was associated with a significant increase in MTX-induced whole cell membrane currents. The effect of MTX on whole cell currents in both wild-type and PMCA overexpressing HEK cells was sensitive to pump ligands including Ca2+and ATP. MTX-induced currents were significantly reduced by knockdown of PMCA1 in HEK cells using small interfering RNA or in mouse embryonic fibroblasts from genetically modified mice with the PMCA1(+/−) PMCA4(−/−) genotype. Finally, PMCA catalytic activity (i.e., Ca2+-ATPase) in isolated membranes, or in purified PMCA preparations, was inhibited by MTX. Together, these results suggest that MTX binds to and converts the PMCA pump into a Ca2+-permeable nonselective cation channel.
IFNγ regulates retinal pigment epithelial fluid transport
Authors: Li Rong , Maminishkis Arvydas , Banzon Tina , Wan Qin , Jalickee Stephen , Chen Shan , Miller Sheldon S.
Published: October 2009

The present experiments show that IFNγ receptors are mainly localized to the basolateral membrane of human retinal pigment epithelium (RPE). Activation of these receptors in primary cultures of human fetal RPE inhibited cell proliferation and migration, decreased RPE mitochondrial membrane potential, altered transepithelial potential and resistance, and significantly increased transepithelial fluid absorption. These effects are mediated through JAK-STAT and p38 MAPK signaling pathways. Second messenger signaling through cAMP-PKA pathway- and interferon regulatory factor-1-dependent production of nitric oxide/cGMP stimulated the CFTR at the basolateral membrane and increased transepithelial fluid absorption. In vivo experiments using a rat model of retinal reattachment showed that IFNγ applied to the anterior surface of the eye can remove extra fluid deposited in the extracellular or subretinal space between the retinal photoreceptors and RPE. Removal of this extra fluid was blocked by a combination of PKA and JAK-STAT pathway inhibitors injected into the subretinal space. These results demonstrate a protective role for IFNγ in regulating retinal hydration across the outer blood-retinal barrier in inflammatory disease processes and provide the basis for possible therapeutic interventions.
Expression of glucose-dependent insulinotropic polypeptide in the zebrafish
Authors: Musson Michelle C. , Jepeal Lisa I. , Mabray Patrick D. , Zhdanova Irina V. , Cardoso Wellington V. , Wolfe M. Michael
Published: October 2009

In mammals, glucose-dependent insulinotropic polypeptide (GIP) is synthesized predominately in the small intestine and functions in conjunction with insulin to promote nutrient deposition. However, little is known regarding GIP expression and function in early vertebrates like the zebrafish, a model organism representing an early stage in the evolutionary development of the compound vertebrate pancreas. Analysis of GIP and insulin ( insa) expression in zebrafish larvae by RT-PCR demonstrated that although insa was detected as early as 24 h postfertilization (hpf), GIP expression was not demonstrated until 72 hpf, shortly after the completion of endocrine pancreatic development but prior to the commencement of independent feeding. Furthermore, whole mount in situ hybridization of zebrafish larvae showed expression of GIP and insa in the same tissues, and in adult zebrafish, RT-PCR and immunohistochemistry demonstrated GIP expression in both the intestine and the pancreas. Receptor activation studies showed that zebrafish GIP was capable of activating the rat GIP receptor. Although previous studies have identified four receptors with glucagon receptor-like sequences in the zebrafish, one of which possesses the capacity to bind GIP, a functional analysis of these receptors has not been performed. This study demonstrates interactions between the latter receptor and zebrafish GIP, identifying it as a potential in vivo target for the ligand. Finally, food deprivation studies in larvae demonstrated an increase in GIP and proglucagon II mRNA levels in response to fasting. In conclusion, the results of these studies suggest that although the zebrafish appears to be a model of an early stage of evolutionary development of GIP expression, the peptide may not possess incretin properties in this species.
Prostasin-dependent activation of epithelial Na+channels by low plasmin concentrations
Authors: Svenningsen Per , Uhrenholt Torben R. , Palarasah Yaseelan , Skjødt Karsten , Jensen Boye L. , Skøtt Ole
Published: October 2009

Several pathophysiological conditions, including nephrotic syndrome, are characterized by increased renal activity of the epithelial Na+channel (ENaC). We recently identified plasmin in nephrotic urine as a stimulator of ENaC activity and undertook this study to investigate the mechanism by which plasmin stimulates ENaC activity. Cy3-labeled plasmin was found to bind to the surface of the mouse cortical collecting duct cell line, M-1. Binding depended on a glycosylphosphatidylinositol (GPI)-anchored protein. Biotin-label transfer showed that plasmin interacted with the GPI-anchored protein prostasin on M-1 cells and that plasmin cleaved prostasin. Prostasin activates ENaC by cleavage of the γ-subunit, which releases an inhibitory peptide from the extracellular domain. Removal of GPI-anchored proteins from the M-1 cells with phosphatidylinositol-specific phospholipase C (PI-PLC) inhibited plasmin-stimulated ENaC current in monolayers of M-1 cells at low plasmin concentration (1–4 μg/ml). At a high plasmin concentration of 30 μg/ml, there was no difference between cell layers treated with or without PI-PLC. Knockdown of prostasin attenuated binding of plasmin to M1 cells and blocked plasmin-stimulated ENaC current in single M-1 cells, as measured by whole-cell patch clamp. In M-1 cells expressing heterologous FLAG-tagged prostasin, γENaC and prostasin were colocalized. A monoclonal antibody directed against the inhibitory peptide of γENaC produced specific immunofluorescence labeling of M-1 cells. Pretreatment with plasmin abolished labeling of M-1 cells in a prostasin-dependent way. We conclude that, at low concentrations, plasmin interacts with GPI-anchored prostasin, which leads to cleavage of the γ-subunit and activation of ENaC, while at higher concentrations, plasmin directly activates ENaC.
Glucose homeostasis is impaired by a paradoxical interaction between metformin and insulin in carnivorous rainbow trout
Authors: Polakof S. , Skiba-Cassy S. , Panserat S.
Published: October 2009

Utilizing rainbow trout ( Oncorhynchus mykiss ) as a known model of a “glucose-intolerant” and poor dietary glucose user, we assessed glucose utilization in fish chronically receiving two molecules able to improve glucose homeostasis: insulin and metformin. Our objectives were to assess the ability of rainbow trout to deal with a glucose load and to improve glucose utilization in fish receiving a chronic administration of insulin plus metformin treatments. Fish received (implanted miniosmotic pumps) saline, insulin, metformin, and insulin plus metformin solution for 4 days and then were subjected to a glucose challenge (intraperitoneal injection) to study glucose homeostasis, analyzing plasma glycemia, mRNA levels of glucose metabolism-related proteins, insulin signaling, and glycogen levels in liver and muscle. Control fish received a saline pump implantation and saline intraperitoneal injection. We found no evidence that the “glucose intolerance” in this species could be linked to any of the molecular markers of metabolism in the tissues analyzed. By contrast, very interestingly, we show for the first time, that metformin is not only unable to improve glucose homeostasis in trout, but, in fact, its counteracts the effects of insulin, creating an “insulin resistance,” especially in the muscle. These results make trout an attractive original model to study both insulin and metformin effect on biological systems.
Comparative physiology of the pulmonary blood-gas barrier: the unique avian solution
Authors: West John B.
Published: October 2009

Two opposing selective pressures have shaped the evolution of the structure of the blood-gas barrier in air breathing vertebrates. The first pressure, which has been recognized for 100 years, is to facilitate diffusive gas exchange. This requires the barrier to be extremely thin and have a large area. The second pressure, which has only recently been appreciated, is to maintain the mechanical integrity of the barrier in the face of its extreme thinness. The most important tensile stress comes from the pressure within the pulmonary capillaries, which results in a hoop stress. The strength of the barrier can be attributed to the type IV collagen in the extracellular matrix. In addition, the stress is minimized in mammals and birds by complete separation of the pulmonary and systemic circulations. Remarkably, the avian barrier is about 2.5 times thinner than that in mammals and also is much more uniform in thickness. These advantages for gas exchange come about because the avian pulmonary capillaries are unique among air breathers in being mechanically supported externally in addition to the strength that comes from the structure of their walls. This external support comes from epithelial plates that are part of the air capillaries, and the support is available because the terminal air spaces in the avian lung are extremely small due to the flow-through nature of ventilation in contrast to the reciprocating pattern in mammals.
Carbachol-induced rabbit bladder smooth muscle contraction: roles of protein kinase C and Rho kinase
Authors: Wang Tanchun , Kendig Derek M. , Smolock Elaine M. , Moreland Robert S.
Published: October 2009

Smooth muscle contraction is regulated by phosphorylation of the myosin light chain (MLC) catalyzed by MLC kinase and dephosphorylation catalyzed by MLC phosphatase. Agonist stimulation of smooth muscle results in the inhibition of MLC phosphatase activity and a net increase in MLC phosphorylation and therefore force. The two pathways believed to be primarily important for inhibition of MLC phosphatase activity are protein kinase C (PKC)-catalyzed CPI-17 phosphorylation and Rho kinase (ROCK)-catalyzed myosin phosphatase-targeting subunit (MYPT1) phosphorylation. The goal of this study was to determine the roles of PKC and ROCK and their downstream effectors in regulating MLC phosphorylation levels and force during the phasic and sustained phases of carbachol-stimulated contraction in intact bladder smooth muscle. These studies were performed in the presence and absence of the PKC inhibitor bisindolylmaleimide-1 (Bis) or the ROCK inhibitor H-1152. Phosphorylation levels of Thr38-CPI-17 and Thr696/Thr850-MYPT1 were measured at different times during carbachol stimulation using site-specific antibodies. Thr38-CPI-17 phosphorylation increased concurrently with carbachol-stimulated force generation. This increase was reduced by inhibition of PKC during the entire contraction but was only reduced by ROCK inhibition during the sustained phase of contraction. MYPT1 showed high basal phosphorylation levels at both sites; however, only Thr850phosphorylation increased with carbachol stimulation; the increase was abolished by the inhibition of either ROCK or PKC. Our results suggest that during agonist stimulation, PKC regulates MLC phosphatase activity through phosphorylation of CPI-17. In contrast, ROCK phosphorylates both Thr850-MYPT1 and CPI-17, possibly through cross talk with a PKC pathway, but is only significant during the sustained phase of contraction. Last, our results demonstrate that there is a constitutively activate pool of ROCK that phosphorylates MYPT1 in the basal state, which may account for the high resting levels of MLC phosphorylation measured in rabbit bladder smooth muscle.
Aberrant planar cell polarity induced by urinary tract obstruction
Authors: Li Ling , Zepeda-Orozco Diana , Patel Vishal , Truong Phu , Karner Courtney M. , Carroll Thomas J. , Lin Fangming
Published: October 2009

Flow sensing by primary cilia of the epithelial cells is involved in cystogenesis in polycystic kidney disease. We investigate whether a similar mechanism applies to the pathogenesis of cyst-like tubular dilatation induced by ureteral obstruction in mice. Robust proliferation occurs in the obstructed tubules when urine flow is interrupted as well as in the repairing tubules when urine flow is reestablished after relief of the obstruction, suggesting a urine flow-independent mechanism of proliferation. In the urothelium, proliferation is only detected above the obstruction, although urine flow ceased both above and below the obstruction. Our results support mechanical strain- rather than flow-mediated proliferation in obstructive uropathy. To understand the mechanism of cell proliferation leading to increased tubular diameter in cyst-like tubular dilatation, we examine planar cell polarity (PCP), which is necessary for oriented cell division and maintenance of tubular diameter. In dilated tubules, the orientation of cell division is randomized, atypical PKC (aPKC) is mislocalized, and the pattern of the expression of a core PCP protein, Frizzled3 (Fz3), is altered. In addition, the level of Fz3 expression is increased. These results indicate that aberrant PCP may contribute to cyst-like tubular dilatation in obstructive uropathy. Interestingly, the orientation of cell division, localization of aPKC, and Fz3 expression return to normal when obstruction is relieved, which suggest a role of normal PCP signaling in tubular repair.
PTH transiently increases the percent mobile fraction of Npt2a in OK cells as determined by FRAP
Authors: Weinman Edward J. , Steplock Deborah , Cha Boyoung , Kovbasnjuk Olga , Frost Nicholas A. , Cunningham Rochelle , Shenolikar Shirish , Blanpied Thomas A. , Donowitz Mark
Published: October 2009

Renal sodium-dependent phosphate transporter 2a (Npt2a) binds to a number of PDZ adaptor proteins including sodium-hydrogen exchanger regulatory factor-1 (NHERF-1), which regulates its retention in the apical membrane of renal proximal tubule cells and the response to parathyroid hormone (PTH). The present experiments were designed to study the lateral mobility of enhanced green fluorescent protein (EGFP)-Npt2a in proximal tubule-like opossum kidney (OK) cells using fluorescence recovery after photobleaching (FRAP) and to determine the role of PDZ binding proteins in mediating the effects of PTH. The mobile fraction of wild-type Npt2a (EGFP-Npt2a-TRL) under basal conditions was ∼17%. Treatment of the cells with Bis(sulfosuccinimidyl) suberate, a water-soluble cross-linker, abolished recovery nearly completely, indicating that recovery represented lateral diffusion in the plasma membrane and not the exocytosis or synthesis of unbleached transporter. Substitution of the C-terminal amino acid PDZ binding sequence TRL with AAA (EGFP-Npt2a-AAA) resulted in a nearly twofold increase in percent mobile fraction of Npt2a. Treatment of cells with PTH resulted in a rapid increase in the percent mobile fraction to >30% followed by a time-dependent decrease to baseline or below. PTH had no effect on the mobility of EGFP-Npt2a-AAA expressed in native OK cells or on wild-type EGFP-Npt2a-TRL expressed in OK-H cells deficient in NHERF-1. These findings indicate that the association of Npt2a with PDZ binding proteins limits the lateral mobility of the transporter in the apical membrane of renal proximal tubule cells. Treatment with PTH, presumably by dissociating NHERF-1/Npt2a complexes, transiently increases the mobility of Npt2a, suggesting that freeing of Npt2a from the cytoskeleton precedes PTH-mediated endocytosis.
Shared Bimanual Tasks Elicit Bimanual Reflexes During Movement
Authors: Mutha Pratik K. , Sainburg Robert L.
Published: October 2009

Previous research has suggested distinct predictive and reactive control mechanisms for bimanual movements compared with unimanual motion. Recent studies have extended these findings by demonstrating that movement corrections during bimanual movements might differ depending on whether or not the task is shared between the arms. We hypothesized that corrective responses during shared bimanual tasks recruit bilateral rapid feedback mechanisms such as reflexes. We tested this hypothesis by perturbing one arm as subjects performed uni- and bimanual movements. Movements were made in a virtual-reality environment in which hand position was displayed as a cursor on a screen. During bimanual motion, we provided cursor feedback either independently for each arm (independent-cursor) or such that one cursor was placed at the average location between the arms (shared-cursor). On random trials, we applied a 40 N force pulse to the right arm 100 ms after movement onset. Our results show that while reflex responses were rapidly elicited in the perturbed arm, electromyographic activity remained close to baseline levels in the unperturbed arm during the independent-cursor trials. In contrast, when the cursor was shared between the arms, reflex responses were reduced in the perturbed arm and were rapidly elicited in the unperturbed arm. Our results thus suggest that when both arms contribute to achieving the task goal, reflex responses are bilaterally elicited in response to unilateral perturbations. These results agree with and extend recent suggestions that bimanual feedback control might be modified depending on task context.
High-Amplitude Positive Spikes Recorded Extracellularly in Cat Visual Cortex
Authors: Gold Carl , Girardin Cyrille C. , Martin Kevan A. C. , Koch Christof
Published: October 2009

We simulated the shape and amplitude of extracellular action potentials (APs or “spikes”) using biophysical models based on detailed reconstructions of single neurons from the cat's visual cortex. We compared these predictions with spikes recorded from the cat's primary visual cortex under a standard protocol. The experimental data were derived from a large number of neurons throughout all layers. The majority of spikes were biphasic, with a dominant negative peak (mean amplitude, −0.11 mV), whereas a minority of APs had a dominant positive peak of +0.54-mV mean amplitude, with a maximum of +1.5 mV. The largest positive amplitude spikes were recorded in layer 5. The simulations demonstrated that a pyramidal neuron under known biophysical conditions may generate a negative peak with amplitude up to −1.5 mV, but that the amplitude of the positive peak may be at most 0.5 mV. We confirmed that spikes with large positive peaks were not produced by juxtacellular patch recordings. We conclude that there is a significant gap in our present understanding of either the spike-generation process in pyramidal neurons, the biophysics of extracellular recording, or both.
Postpartum Ovarian Vein Thrombosis: Two Cases and Review of Literature
Authors: Akinbiyi Amos A. , Nguyen Rita , Katz Michael
Published: October 2009

Introduction. We presented two cases of late presentation of ovarian vein thrombosis postpartum following vaginal delivery and cesarean section within a short period in our institution. Both of them had pelvic pain following their deliveries which was associated with fever and chills. One of them was quite a big-sized thrombophlebitic vein which was about10×6×5centimeters following a computed tomography. They were both treated initially for urinary tract infection, while a large ovarian vein thrombosis was not diagnosed in the second patient until her emergency department admission.Conclusion. Ovarian vein thrombosis is rare, but could present late, and difficult to diagnose, hence, should be considered as a differential diagnosis in a postpartum woman with fever and tender pelvic mass.
A Two‐Time Scale Decentralized Model Predictive Controller Based on Input and Output Model
Authors: Niu Jian , Zhao Jun , Xu Zuhua , Qian Jixin
Published: October 2009

A decentralized model predictive controller applicable for some systems which exhibit different dynamic characteristics in different channels was presented in this paper. These systems can be regarded as combinations of a fast model and a slow model, the response speeds of which are in two‐time scale. Because most practical models used for control are obtained in the form of transfer function matrix by plant tests, a singular perturbation method was firstly used to separate the original transfer function matrix into two models in two‐time scale. Then a decentralized model predictive controller was designed based on the two models derived from the original system. And the stability of the control method was proved. Simulations showed that the method was effective.
Image Restoration Using Functional and Anatomical Information Fusion with Application to SPECT‐MRI Images
Authors: Benameur S. , Mignotte M. , Meunier J. , Soucy J.-P.
Published: October 2009

Image restoration is usually viewed as an ill‐posed problem in image processing, since there is no unique solution associated with it. The quality of restored image closely depends on the constraints imposed of the characteristics of the solution. In this paper, we propose an original extension of the NAS‐RIF restoration technique by using information fusion as prior information with application in SPECT medical imaging. That extension allows the restoration process to be constrained by efficiently incorporating, within the NAS‐RIF method, a regularization term which stabilizes the inverse solution. Our restoration method is constrained by anatomical information extracted from a high resolution anatomical procedure such as magnetic resonance imaging (MRI). This structural anatomy‐based regularization term uses the result of an unsupervised Markovian segmentation obtained after a preliminary registration step between the MRI and SPECT data volumes from each patient. This method was successfully tested on 30 pairs of brain MRI and SPECT acquisitions from different subjects and on Hoffman and Jaszczak SPECT phantoms. The experiments demonstrated that the method performs better, in terms of signal‐to‐noise ratio, than a classical supervised restoration approach using a Metz filter.
Efficient Identification of Assembly Neurons within Massively Parallel Spike Trains
Authors: Berger Denise , Borgelt Christian , Louis Sebastien , Morrison Abigail , Grün Sonja
Published: October 2009

The chance of detecting assembly activity is expected to increase if the spiking activities of large numbers of neurons are recorded simultaneously. Although such massively parallel recordings are now becoming available, methods able to analyze such data for spike correlation are still rare, as a combinatorial explosion often makes it infeasible to extend methods developed for smaller data sets. By evaluating pattern complexity distributions the existence of correlated groups can be detected, but their member neurons cannot be identified. In this contribution, we present approaches to actually identify the individual neurons involved in assemblies. Our results may complement other methods and also provide a way to reduce data sets to the “relevant” neurons, thus allowing us to carry out a refined analysis of the detailed correlation structure due to reduced computation time.
Solitary Wave Solutions for a Time‐Fraction Generalized Hirota‐Satsuma Coupled KdV Equation by a New Analytical Technique
Authors: Shateri Majid , Ganji D. D.
Published: October 2009

A new iterative technique is employed to solve a system of nonlinear fractional
partial differential equations. This new approach requires neither Lagrange multiplier like
variational iteration method (VIM) nor polynomials like Adomian′s decomposition method (ADM)
so that can be more easily and effectively established for solving nonlinear fractional differential
equations, and will overcome the limitations of these methods. The obtained numerical results show
good agreement with those of analytical solutions. The fractional derivatives are described in
Caputo sense.
Phosphatidylinositol 3-Kinase Regulates Macrophage Responses to Double-Stranded RNA and Encephalomyocarditis Virus
Authors: Freudenburg Wieke , Moran Jason M. , Lents Nathan H. , Baldassare Joseph J. , Buller R. Mark L. , Corbett John A.
Published: October 2009

Virus infection of macrophages stimulates the expression of proinflammatory and antiviral genes interleukin-1 (IL-1), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). In this study, we show that phosphatidylinositol 3-kinase (PI3K) is required for the inflammatory response of macrophages to virus infection. When macrophages are infected with encephalomyocarditis virus (EMCV) there is a rapid and transient activation of PI3K and phosphorylation of its downstream target Akt. Inhibitors of PI3K attenuate EMCV- and double-stranded RNA-induced iNOS, COX-2 and IL-1β expression in RAW264.7 cells and mouse peritoneal macrophages. The attenuation of inflammatory gene expression in response to PI3K inhibition correlates with the induction of macrophage apoptosis. The morphology of macrophages shifts from activation in response to EMCV infection to apoptosis in the cells treated with PI3K inhibitors and EMCV. These morphological changes are accompanied by the activation of caspase-3. These findings suggest that PI3K plays a central role in the regulation of macrophage responses to EMCV infection. When PI3K is activated, it participates in the regulation of inflammatory gene expression; however, if PI3K is inhibited macrophages are unable to mount an inflammatory antiviral response and die by apoptosis.