An allosteric binding site at the human serotonin transporter mediates the inhibition of escitalopram by R-citalopram: kinetic binding studies with the ALI/VFL-SI/TT mutant.

Science.gov (United States)

Zhong, Huailing; Hansen, Kasper B; Boyle, Noel J; Han, Kiho; Muske, Galina; Huang, Xinyan; Egebjerg, Jan; Sánchez, Connie

2009-10-25

The human serotonin transporter (hSERT) has primary and allosteric binding sites for escitalopram and R-citalopram. Previous studies have established that the interaction of these two compounds at a low affinity allosteric binding site of hSERT can affect the dissociation of [(3)H]escitalopram from hSERT. The allosteric binding site involves a series of residues in the 10th, 11th, and 12th trans-membrane domains of hSERT. The low affinity allosteric activities of escitalopram and R-citalopram are essentially eliminated in a mutant hSERT with changes in some of these residues, namely A505V, L506F, I507L, S574T, I575T, as measured in dissociation binding studies. We confirm that in association binding experiments, R-citalopram at clinically relevant concentrations reduces the association rate of [(3)H]escitalopram as a ligand to wild type hSERT. We demonstrate that the ability of R-citalopram to reduce the association rate of escitalopram is also abolished in the mutant hSERT (A505V, L506F, I507L, S574T, I575T), along with the expected disruption the low affinity allosteric function on dissociation binding. This suggests that the allosteric binding site mediates both the low affinity and higher affinity interactions between R-citalopram, escitalopram, and hSERT. Our data add an additional structural basis for the different efficacies of escitalopram compared to racemic citalopram reported in animal studies and clinical trials, and substantiate the hypothesis that hSERT has complex allosteric mechanisms underlying the unexplained in vivo activities of its inhibitors.

Extracellular loop 2 of the free Fatty Acid receptor 2 mediates allosterism of a phenylacetamide ago-allosteric modulator

DEFF Research Database (Denmark)

Smith, Nicola J; Ward, Richard J; Stoddart, Leigh A

2011-01-01

Allosteric agonists are powerful tools for exploring the pharmacology of closely related G protein-coupled receptors that have nonselective endogenous ligands, such as the short chain fatty acids at free fatty acid receptors 2 and 3 (FFA2/GPR43 and FFA3/GPR41, respectively). We explored the molec...

Change in Allosteric Network Affects Binding Affinities of PDZ Domains: Analysis through Perturbation Response Scanning

Science.gov (United States)

Gerek, Z. Nevin; Ozkan, S. Banu

2011-01-01

The allosteric mechanism plays a key role in cellular functions of several PDZ domain proteins (PDZs) and is directly linked to pharmaceutical applications; however, it is a challenge to elaborate the nature and extent of these allosteric interactions. One solution to this problem is to explore the dynamics of PDZs, which may provide insights about how intramolecular communication occurs within a single domain. Here, we develop an advancement of perturbation response scanning (PRS) that couples elastic network models with linear response theory (LRT) to predict key residues in allosteric transitions of the two most studied PDZs (PSD-95 PDZ3 domain and hPTP1E PDZ2 domain). With PRS, we first identify the residues that give the highest mean square fluctuation response upon perturbing the binding sites. Strikingly, we observe that the residues with the highest mean square fluctuation response agree with experimentally determined residues involved in allosteric transitions. Second, we construct the allosteric pathways by linking the residues giving the same directional response upon perturbation of the binding sites. The predicted intramolecular communication pathways reveal that PSD-95 and hPTP1E have different pathways through the dynamic coupling of different residue pairs. Moreover, our analysis provides a molecular understanding of experimentally observed hidden allostery of PSD-95. We show that removing the distal third alpha helix from the binding site alters the allosteric pathway and decreases the binding affinity. Overall, these results indicate that (i) dynamics plays a key role in allosteric regulations of PDZs, (ii) the local changes in the residue interactions can lead to significant changes in the dynamics of allosteric regulations, and (iii) this might be the mechanism that each PDZ uses to tailor their binding specificities regulation. PMID:21998559

DISTANCE LEARNERSÕ PERCEPTIONS OF COMPUTER MEDIATED COMMUNICATION

OpenAIRE

Mujgan Bozkaya; Irem Erdem Aydin

2011-01-01

In this study, perspectives of the first year students in the completely online Information Management Associate Degree Program at Anadolu University regarding computer as a communication medium were investigated. StudentsÕ perspectives on computer-mediated communications were analyzed in the light of three different views in the area of computer-mediated communications: The first view suggests that face-to-face settings are better communication environments compared to computer-mediated envi...

Molecular sites for the positive allosteric modulation of glycine receptors by endocannabinoids.

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Gonzalo E Yévenes

Full Text Available Glycine receptors (GlyRs are transmitter-gated anion channels of the Cys-loop superfamily which mediate synaptic inhibition at spinal and selected supraspinal sites. Although they serve pivotal functions in motor control and sensory processing, they have yet to be exploited as drug targets partly because of hitherto limited possibilities for allosteric control. Endocannabinoids (ECs have recently been characterized as direct allosteric GlyR modulators, but the underlying molecular sites have remained unknown. Here, we show that chemically neutral ECs (e.g. anandamide, AEA are positive modulators of α(1, α(2 and α(3 GlyRs, whereas acidic ECs (e.g. N-arachidonoyl-glycine; NA-Gly potentiate α(1 GlyRs but inhibit α(2 and α(3. This subunit-specificity allowed us to identify the underlying molecular sites through analysis of chimeric and mutant receptors. We found that alanine 52 in extracellular loop 2, glycine 254 in transmembrane (TM region 2 and intracellular lysine 385 determine the positive modulation of α(1 GlyRs by NA-Gly. Successive substitution of non-conserved extracellular and TM residues in α(2 converted NA-Gly-mediated inhibition into potentiation. Conversely, mutation of the conserved lysine within the intracellular loop between TM3 and TM4 attenuated NA-Gly-mediated potentiation of α(1 GlyRs, without affecting inhibition of α(2 and α(3. Notably, this mutation reduced modulation by AEA of all three GlyRs. These results define molecular sites for allosteric control of GlyRs by ECs and reveal an unrecognized function for the TM3-4 intracellular loop in the allosteric modulation of Cys-loop ion channels. The identification of these sites may help to understand the physiological role of this modulation and facilitate the development of novel therapeutic approaches to diseases such as spasticity, startle disease and possibly chronic pain.

Convergent transmission of RNAi guide-target mismatch information across Argonaute internal allosteric network.

Science.gov (United States)

Joseph, Thomas T; Osman, Roman

2012-01-01

In RNA interference, a guide strand derived from a short dsRNA such as a microRNA (miRNA) is loaded into Argonaute, the central protein in the RNA Induced Silencing Complex (RISC) that silences messenger RNAs on a sequence-specific basis. The positions of any mismatched base pairs in an miRNA determine which Argonaute subtype is used. Subsequently, the Argonaute-guide complex binds and silences complementary target mRNAs; certain Argonautes cleave the target. Mismatches between guide strand and the target mRNA decrease cleavage efficiency. Thus, loading and silencing both require that signals about the presence of a mismatched base pair are communicated from the mismatch site to effector sites. These effector sites include the active site, to prevent target cleavage; the binding groove, to modify nucleic acid binding affinity; and surface allosteric sites, to control recruitment of additional proteins to form the RISC. To examine how such signals may be propagated, we analyzed the network of internal allosteric pathways in Argonaute exhibited through correlations of residue-residue interactions. The emerging network can be described as a set of pathways emanating from the core of the protein near the active site, distributed into the bulk of the protein, and converging upon a distributed cluster of surface residues. Nucleotides in the guide strand "seed region" have a stronger relationship with the protein than other nucleotides, concordant with their importance in sequence selectivity. Finally, any of several seed region guide-target mismatches cause certain Argonaute residues to have modified correlations with the rest of the protein. This arises from the aggregation of relatively small interaction correlation changes distributed across a large subset of residues. These residues are in effector sites: the active site, binding groove, and surface, implying that direct functional consequences of guide-target mismatches are mediated through the cumulative effects of

Dynamic Coupling and Allosteric Networks in the α Subunit of Heterotrimeric G Proteins.

Science.gov (United States)

Yao, Xin-Qiu; Malik, Rabia U; Griggs, Nicholas W; Skjærven, Lars; Traynor, John R; Sivaramakrishnan, Sivaraj; Grant, Barry J

2016-02-26

G protein α subunits cycle between active and inactive conformations to regulate a multitude of intracellular signaling cascades. Important structural transitions occurring during this cycle have been characterized from extensive crystallographic studies. However, the link between observed conformations and the allosteric regulation of binding events at distal sites critical for signaling through G proteins remain unclear. Here we describe molecular dynamics simulations, bioinformatics analysis, and experimental mutagenesis that identifies residues involved in mediating the allosteric coupling of receptor, nucleotide, and helical domain interfaces of Gαi. Most notably, we predict and characterize novel allosteric decoupling mutants, which display enhanced helical domain opening, increased rates of nucleotide exchange, and constitutive activity in the absence of receptor activation. Collectively, our results provide a framework for explaining how binding events and mutations can alter internal dynamic couplings critical for G protein function. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Computer-Mediated Communication Systems

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Bin Yu

2011-10-01

Full Text Available The essence of communication is to exchange and share information. Computers provide a new medium to human communication. CMC system, composed of human and computers, absorbs and then extends the advantages of all former formats of communication, embracing the instant interaction of oral communication, the abstract logics of printing dissemination, and the vivid images of movie and television. It also creates a series of new communication formats, such as Hyper Text, Multimedia etc. which are the information organizing methods, and cross-space message delivering patterns. Benefiting from the continuous development of technique and mechanism, the computer-mediated communication makes the dream of transmitting information cross space and time become true, which will definitely have a great impact on our social lives.

Social cognitive mediators of parent-child sexual communication.

Science.gov (United States)

Evans, W Douglas; Blitstein, Jonathan L; Davis, Kevin C

2011-07-01

To test a social cognitive behavior change model and identify mediators of the effects of the Parents Speak Up National Campaign (PSUNC) on parent-child sexual communication. Investigators used 5 waves of data from an online randomized controlled trial. Latent variables were developed based on item response theory and confirmatory factor analysis. Structural equation modeling was used to test mediation. Outcome expectations mediated effects of social norms and self-efficacy on sexual communication. Other hypothesized mediators were not confirmed. Interventions to promote parent-child sexual communication should target outcome expectations. Future research should investigate parents' health information seeking.

INTERCULTURAL COMMUNICATION PATTERNS AND LANGUAGE USE IN COMPUTER MEDIATED-COMMUNICATION

OpenAIRE

Adriana Teodorescu

2012-01-01

This paper aims at analyzing the degree to which intercultural communication patterns are embedded in computer-mediated communication. Drawing on Hall's and Hofstede's intercultural communication dimensions, this study evaluates empirically high-versus-low context cultural orientations as reflected in the electronic medium, namely the blog, in three different cultures. Cultural variation is also analyzed in linguistic features and communication style in a synchronous mode of communication, by...

Integrating Computer-Mediated Communication Strategy Instruction

Science.gov (United States)

McNeil, Levi

2016-01-01

Communication strategies (CSs) play important roles in resolving problematic second language interaction and facilitating language learning. While studies in face-to-face contexts demonstrate the benefits of communication strategy instruction (CSI), there have been few attempts to integrate computer-mediated communication and CSI. The study…

Endocannabinoids mediate neuron-astrocyte communication.

Science.gov (United States)

Navarrete, Marta; Araque, Alfonso

2008-03-27

Cannabinoid receptors play key roles in brain function, and cannabinoid effects in brain physiology and drug-related behavior are thought to be mediated by receptors present in neurons. Neuron-astrocyte communication relies on the expression by astrocytes of neurotransmitter receptors. Yet, the expression of cannabinoid receptors by astrocytes in situ and their involvement in the neuron-astrocyte communication remain largely unknown. We show that hippocampal astrocytes express CB1 receptors that upon activation lead to phospholipase C-dependent Ca2+ mobilization from internal stores. These receptors are activated by endocannabinoids released by neurons, increasing astrocyte Ca2+ levels, which stimulate glutamate release that activates NMDA receptors in pyramidal neurons. These results demonstrate the existence of endocannabinoid-mediated neuron-astrocyte communication, revealing that astrocytes are targets of cannabinoids and might therefore participate in the physiology of cannabinoid-related addiction. They also reveal the existence of an endocannabinoid-glutamate signaling pathway where astrocytes serve as a bridge for nonsynaptic interneuronal communication.

The future of type 1 cannabinoid receptor allosteric ligands.

Science.gov (United States)

Alaverdashvili, Mariam; Laprairie, Robert B

2018-02-01

Allosteric modulation of the type 1 cannabinoid receptor (CB1R) holds great therapeutic potential. This is because allosteric modulators do not possess intrinsic efficacy, but instead augment (positive allosteric modulation) or diminish (negative allosteric modulation) the receptor's response to endogenous ligand. Consequently, CB1R allosteric modulators have an effect ceiling which allows for the tempering of CB1R signaling without the desensitization, tolerance, dependence, and psychoactivity associated with orthosteric compounds. Pain, movement disorders, epilepsy, obesity are all potential therapeutic targets for CB1R allosteric modulation. Several challenges exist for the development of CB1R allosteric modulators, such as receptor subtype specificity, translation to in vivo systems, and mixed allosteric/agonist/inverse agonist activity. Despite these challenges, elucidation of crystal structures of CB1R and compound design based on structure-activity relationships will advance the field. In this review, we will cover recent progress for CB1R allosteric modulators and discuss the future promise of this research.

Heat Capacity Changes and Disorder-to-Order Transitions in Allosteric Activation.

Science.gov (United States)

Cressman, William J; Beckett, Dorothy

2016-01-19

Allosteric coupling in proteins is ubiquitous but incompletely understood, particularly in systems characterized by coupling over large distances. Binding of the allosteric effector, bio-5'-AMP, to the Escherichia coli biotin protein ligase, BirA, enhances the protein's dimerization free energy by -4 kcal/mol. Previous studies revealed that disorder-to-order transitions at the effector binding and dimerization sites, which are separated by 33 Å, are integral to functional coupling. Perturbations to the transition at the ligand binding site alter both ligand binding and coupled dimerization. Alanine substitutions in four loops on the dimerization surface yield a range of energetic effects on dimerization. A glycine to alanine substitution at position 142 in one of these loops results in a complete loss of allosteric coupling, disruption of the disorder-to-order transitions at both functional sites, and a decreased affinity for the effector. In this work, allosteric communication between the effector binding and dimerization surfaces in BirA was further investigated by performing isothermal titration calorimetry measurements on nine proteins with alanine substitutions in three dimerization surface loops. In contrast to BirAG142A, at 20 °C all variants bind to bio-5'-AMP with free energies indistinguishable from that measured for wild-type BirA. However, the majority of the variants exhibit altered heat capacity changes for effector binding. Moreover, the ΔCp values correlate with the dimerization free energies of the effector-bound proteins. These thermodynamic results, combined with structural information, indicate that allosteric activation of the BirA monomer involves formation of a network of intramolecular interactions on the dimerization surface in response to bio-5'-AMP binding at the distant effector binding site.

Allosteric modulation of G-protein coupled receptors

DEFF Research Database (Denmark)

Jensen, Anders A.; Spalding, Tracy A

2004-01-01

are believed to activate (agonists) or inhibit (competitive antagonists) receptor signalling by binding the receptor at the same site as the endogenous agonist, the orthosteric site. In contrast, allosteric ligands modulate receptor function by binding to different regions in the receptor, allosteric sites....... In recent years, combinatorial chemistry and high throughput screening have helped identify several allosteric GPCR modulators with novel structures, several of which already have become valuable pharmacological tools and may be candidates for clinical testing in the near future. This mini review outlines...... the current status and perspectives of allosteric modulation of GPCR function with emphasis on the pharmacology of endogenous and synthesised modulators, their receptor interactions and the therapeutic prospects of allosteric ligands compared to orthosteric ligands....

THE SCIENCE OF COMMUNICATION AND NEGOTIATION IN MEDIATION

Directory of Open Access Journals (Sweden)

ELENA NEDELCU

2011-04-01

Full Text Available The present study proposes to contribute in clarifying a subject of great actuality and social importance: why does the contemporary society need such mediation and mediators and what are the psycho-social premises of making the process of mediaton more efficient. In the first part, this study keeps the track of identifying the connections and the distinctions between communication-negotiation and mediation. The intercession carries forward with the analysis of the communicational and negotiative abilities of the mediator – premises of efficient mediation. The final part consists in an argument towards the imperative need of mediation felt by the contemporary society at all its levels.

Modulation of global low-frequency motions underlies allosteric regulation: demonstration in CRP/FNR family transcription factors.

Science.gov (United States)

Rodgers, Thomas L; Townsend, Philip D; Burnell, David; Jones, Matthew L; Richards, Shane A; McLeish, Tom C B; Pohl, Ehmke; Wilson, Mark R; Cann, Martin J

2013-09-01

Allostery is a fundamental process by which ligand binding to a protein alters its activity at a distinct site. There is growing evidence that allosteric cooperativity can be communicated by modulation of protein dynamics without conformational change. The mechanisms, however, for communicating dynamic fluctuations between sites are debated. We provide a foundational theory for how allostery can occur as a function of low-frequency dynamics without a change in structure. We have generated coarse-grained models that describe the protein backbone motions of the CRP/FNR family transcription factors, CAP of Escherichia coli and GlxR of Corynebacterium glutamicum. The latter we demonstrate as a new exemplar for allostery without conformation change. We observe that binding the first molecule of cAMP ligand is correlated with modulation of the global normal modes and negative cooperativity for binding the second cAMP ligand without a change in mean structure. The theory makes key experimental predictions that are tested through an analysis of variant proteins by structural biology and isothermal calorimetry. Quantifying allostery as a free energy landscape revealed a protein "design space" that identified the inter- and intramolecular regulatory parameters that frame CRP/FNR family allostery. Furthermore, through analyzing CAP variants from diverse species, we demonstrate an evolutionary selection pressure to conserve residues crucial for allosteric control. This finding provides a link between the position of CRP/FNR transcription factors within the allosteric free energy landscapes and evolutionary selection pressures. Our study therefore reveals significant features of the mechanistic basis for allostery. Changes in low-frequency dynamics correlate with allosteric effects on ligand binding without the requirement for a defined spatial pathway. In addition to evolving suitable three-dimensional structures, CRP/FNR family transcription factors have been selected to

INTERCULTURAL COMMUNICATION PATTERNS AND LANGUAGE USE IN COMPUTER MEDIATED-COMMUNICATION

Directory of Open Access Journals (Sweden)

Adriana Teodorescu

2012-11-01

Full Text Available This paper aims at analyzing the degree to which intercultural communication patterns are embedded in computer-mediated communication. Drawing on Hall’s and Hofstede’s intercultural communication dimensions, this study evaluates empirically high-versus-low context cultural orientations as reflected in the electronic medium, namely the blog, in three different cultures. Cultural variation is also analyzed in linguistic features and communication style in a synchronous mode of communication, by investigating data from several popular blogs from Japan, Germany and Italy.

HUMAN COMMUNICATION AS MEDIATING THE UNITS OF PARAMETERISED ENVIRONMENT

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Josip Stepanic

2004-06-01

Full Text Available Human communication is prevalently a mediated process. Mediators are units of environment, which are attributed functions within the local value set. They are utilised in such a way as to optimise the change of human states. In this article, a mediator-centred interpretation of the human communication is given. The interpretation follows closely the concept of mediated interaction developed within physics. It is conjectured that collection of mediators, which the humans use, has a well-defined average. The averaged collection permits reliable interpretation as a human communication spectrum. Relation of the intensity of a spectral component with regard to different senses, and with regard to intensity of interaction is discussed.

Convergent transmission of RNAi guide-target mismatch information across Argonaute internal allosteric network.

Directory of Open Access Journals (Sweden)

Thomas T Joseph

Full Text Available In RNA interference, a guide strand derived from a short dsRNA such as a microRNA (miRNA is loaded into Argonaute, the central protein in the RNA Induced Silencing Complex (RISC that silences messenger RNAs on a sequence-specific basis. The positions of any mismatched base pairs in an miRNA determine which Argonaute subtype is used. Subsequently, the Argonaute-guide complex binds and silences complementary target mRNAs; certain Argonautes cleave the target. Mismatches between guide strand and the target mRNA decrease cleavage efficiency. Thus, loading and silencing both require that signals about the presence of a mismatched base pair are communicated from the mismatch site to effector sites. These effector sites include the active site, to prevent target cleavage; the binding groove, to modify nucleic acid binding affinity; and surface allosteric sites, to control recruitment of additional proteins to form the RISC. To examine how such signals may be propagated, we analyzed the network of internal allosteric pathways in Argonaute exhibited through correlations of residue-residue interactions. The emerging network can be described as a set of pathways emanating from the core of the protein near the active site, distributed into the bulk of the protein, and converging upon a distributed cluster of surface residues. Nucleotides in the guide strand "seed region" have a stronger relationship with the protein than other nucleotides, concordant with their importance in sequence selectivity. Finally, any of several seed region guide-target mismatches cause certain Argonaute residues to have modified correlations with the rest of the protein. This arises from the aggregation of relatively small interaction correlation changes distributed across a large subset of residues. These residues are in effector sites: the active site, binding groove, and surface, implying that direct functional consequences of guide-target mismatches are mediated through the

Computational study on the inhibitor binding mode and allosteric regulation mechanism in hepatitis C virus NS3/4A protein.

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Weiwei Xue

Full Text Available HCV NS3/4A protein is an attractive therapeutic target responsible for harboring serine protease and RNA helicase activities during the viral replication. Small molecules binding at the interface between the protease and helicase domains can stabilize the closed conformation of the protein and thus block the catalytic function of HCV NS3/4A protein via an allosteric regulation mechanism. But the detailed mechanism remains elusive. Here, we aimed to provide some insight into the inhibitor binding mode and allosteric regulation mechanism of HCV NS3/4A protein by using computational methods. Four simulation systems were investigated. They include: apo state of HCV NS3/4A protein, HCV NS3/4A protein in complex with an allosteric inhibitor and the truncated form of the above two systems. The molecular dynamics simulation results indicate HCV NS3/4A protein in complex with the allosteric inhibitor 4VA adopts a closed conformation (inactive state, while the truncated apo protein adopts an open conformation (active state. Further residue interaction network analysis suggests the communication of the domain-domain interface play an important role in the transition from closed to open conformation of HCV NS3/4A protein. However, the inhibitor stabilizes the closed conformation through interaction with several key residues from both the protease and helicase domains, including His57, Asp79, Asp81, Asp168, Met485, Cys525 and Asp527, which blocks the information communication between the functional domains interface. Finally, a dynamic model about the allosteric regulation and conformational changes of HCV NS3/4A protein was proposed and could provide fundamental insights into the allosteric mechanism of HCV NS3/4A protein function regulation and design of new potent inhibitors.

Exploiting protein flexibility to predict the location of allosteric sites

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Panjkovich Alejandro

2012-10-01

Full Text Available Abstract Background Allostery is one of the most powerful and common ways of regulation of protein activity. However, for most allosteric proteins identified to date the mechanistic details of allosteric modulation are not yet well understood. Uncovering common mechanistic patterns underlying allostery would allow not only a better academic understanding of the phenomena, but it would also streamline the design of novel therapeutic solutions. This relatively unexplored therapeutic potential and the putative advantages of allosteric drugs over classical active-site inhibitors fuel the attention allosteric-drug research is receiving at present. A first step to harness the regulatory potential and versatility of allosteric sites, in the context of drug-discovery and design, would be to detect or predict their presence and location. In this article, we describe a simple computational approach, based on the effect allosteric ligands exert on protein flexibility upon binding, to predict the existence and position of allosteric sites on a given protein structure. Results By querying the literature and a recently available database of allosteric sites, we gathered 213 allosteric proteins with structural information that we further filtered into a non-redundant set of 91 proteins. We performed normal-mode analysis and observed significant changes in protein flexibility upon allosteric-ligand binding in 70% of the cases. These results agree with the current view that allosteric mechanisms are in many cases governed by changes in protein dynamics caused by ligand binding. Furthermore, we implemented an approach that achieves 65% positive predictive value in identifying allosteric sites within the set of predicted cavities of a protein (stricter parameters set, 0.22 sensitivity, by combining the current analysis on dynamics with previous results on structural conservation of allosteric sites. We also analyzed four biological examples in detail, revealing

Development of allosteric modulators of GPCRs for treatment of CNS disorders.

Science.gov (United States)

Nickols, Hilary Highfield; Conn, P Jeffrey

2014-01-01

The discovery of allosteric modulators of G protein-coupled receptors (GPCRs) provides a promising new strategy with potential for developing novel treatments for a variety of central nervous system (CNS) disorders. Traditional drug discovery efforts targeting GPCRs have focused on developing ligands for orthosteric sites which bind endogenous ligands. Allosteric modulators target a site separate from the orthosteric site to modulate receptor function. These allosteric agents can either potentiate (positive allosteric modulator, PAM) or inhibit (negative allosteric modulator, NAM) the receptor response and often provide much greater subtype selectivity than orthosteric ligands for the same receptors. Experimental evidence has revealed more nuanced pharmacological modes of action of allosteric modulators, with some PAMs showing allosteric agonism in combination with positive allosteric modulation in response to endogenous ligand (ago-potentiators) as well as "bitopic" ligands that interact with both the allosteric and orthosteric sites. Drugs targeting the allosteric site allow for increased drug selectivity and potentially decreased adverse side effects. Promising evidence has demonstrated potential utility of a number of allosteric modulators of GPCRs in multiple CNS disorders, including neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and Huntington's disease, as well as psychiatric or neurobehavioral diseases such as anxiety, schizophrenia, and addiction. © 2013.

Conformational changes and allosteric communications in human serum albumin due to ligand binding.

Science.gov (United States)

Ahalawat, Navjeet; Murarka, Rajesh K

2015-01-01

It is well recognized that knowledge of structure alone is not sufficient to understand the fundamental mechanism of biomolecular recognition. Information of dynamics is necessary to describe motions involving relevant conformational states of functional importance. We carried out principal component analysis (PCA) of structural ensemble, derived from 84 crystal structures of human serum albumin (HSA) with different ligands and/or different conditions, to identify the functionally important collective motions, and compared with the motions along the low-frequency modes obtained from normal mode analysis of the elastic network model (ENM) of unliganded HSA. Significant overlap is observed in the collective motions derived from PCA and ENM. PCA and ENM analysis revealed that ligand selects the most favored conformation from accessible equilibrium structures of unliganded HSA. Further, we analyzed dynamic network obtained from molecular dynamics simulations of unliganded HSA and fatty acids- bound HSA. Our results show that fatty acids-bound HSA has more robust community network with several routes to communicate among different parts of the protein. Critical nodes (residues) identified from dynamic network analysis are in good agreement with allosteric residues obtained from sequence-based statistical coupling analysis method. This work underscores the importance of intrinsic structural dynamics of proteins in ligand recognition and can be utilized for the development of novel drugs with optimum activity.

Modulation of global low-frequency motions underlies allosteric regulation: demonstration in CRP/FNR family transcription factors.

Directory of Open Access Journals (Sweden)

Thomas L Rodgers

2013-09-01

Full Text Available Allostery is a fundamental process by which ligand binding to a protein alters its activity at a distinct site. There is growing evidence that allosteric cooperativity can be communicated by modulation of protein dynamics without conformational change. The mechanisms, however, for communicating dynamic fluctuations between sites are debated. We provide a foundational theory for how allostery can occur as a function of low-frequency dynamics without a change in structure. We have generated coarse-grained models that describe the protein backbone motions of the CRP/FNR family transcription factors, CAP of Escherichia coli and GlxR of Corynebacterium glutamicum. The latter we demonstrate as a new exemplar for allostery without conformation change. We observe that binding the first molecule of cAMP ligand is correlated with modulation of the global normal modes and negative cooperativity for binding the second cAMP ligand without a change in mean structure. The theory makes key experimental predictions that are tested through an analysis of variant proteins by structural biology and isothermal calorimetry. Quantifying allostery as a free energy landscape revealed a protein "design space" that identified the inter- and intramolecular regulatory parameters that frame CRP/FNR family allostery. Furthermore, through analyzing CAP variants from diverse species, we demonstrate an evolutionary selection pressure to conserve residues crucial for allosteric control. This finding provides a link between the position of CRP/FNR transcription factors within the allosteric free energy landscapes and evolutionary selection pressures. Our study therefore reveals significant features of the mechanistic basis for allostery. Changes in low-frequency dynamics correlate with allosteric effects on ligand binding without the requirement for a defined spatial pathway. In addition to evolving suitable three-dimensional structures, CRP/FNR family transcription factors have

Oncogenic exon 2 mutations in Mediator subunit MED12 disrupt allosteric activation of cyclin C-CDK8/19.

Science.gov (United States)

Park, Min Ju; Shen, Hailian; Spaeth, Jason M; Tolvanen, Jaana H; Failor, Courtney; Knudtson, Jennifer F; McLaughlin, Jessica; Halder, Sunil K; Yang, Qiwei; Bulun, Serdar E; Al-Hendy, Ayman; Schenken, Robert S; Aaltonen, Lauri A; Boyer, Thomas G

2018-03-30

Somatic mutations in exon 2 of the RNA polymerase II transcriptional Mediator subunit MED12 occur at high frequency in uterine fibroids (UFs) and breast fibroepithelial tumors as well as recurrently, albeit less frequently, in malignant uterine leimyosarcomas, chronic lymphocytic leukemias, and colorectal cancers. Previously, we reported that UF-linked mutations in MED12 disrupt its ability to activate cyclin C (CycC)-dependent kinase 8 (CDK8) in Mediator, implicating impaired Mediator-associated CDK8 activity in the molecular pathogenesis of these clinically significant lesions. Notably, the CDK8 paralog CDK19 is also expressed in myometrium, and both CDK8 and CDK19 assemble into Mediator in a mutually exclusive manner, suggesting that CDK19 activity may also be germane to the pathogenesis of MED12 mutation-induced UFs. However, whether and how UF-linked mutations in MED12 affect CDK19 activation is unknown. Herein, we show that MED12 allosterically activates CDK19 and that UF-linked exon 2 mutations in MED12 disrupt its CDK19 stimulatory activity. Furthermore, we find that within the Mediator kinase module, MED13 directly binds to the MED12 C terminus, thereby suppressing an apparent UF mutation-induced conformational change in MED12 that otherwise disrupts its association with CycC-CDK8/19. Thus, in the presence of MED13, mutant MED12 can bind, but cannot activate, CycC-CDK8/19. These findings indicate that MED12 binding is necessary but not sufficient for CycC-CDK8/19 activation and reveal an additional step in the MED12-dependent activation process, one critically dependent on MED12 residues altered by UF-linked exon 2 mutations. These findings confirm that UF-linked mutations in MED12 disrupt composite Mediator-associated kinase activity and identify CDK8/19 as prospective therapeutic targets in UFs. © 2018 Park et al.

Allosteric transition: a comparison of two models

DEFF Research Database (Denmark)

Bindslev, Niels

2013-01-01

Introduction Two recent models are in use for analysis of allosteric drug action at receptor sites remote from orthosteric binding sites. One is an allosteric two-state mechanical model derived in 2000 by David Hall. The other is an extended operational model developed in 2007 by Arthur...... of model both for simulation and analysis of allosteric concentration-responses at equilibrium or steady-state. Conclusions As detailed knowledge of receptors systems becomes available, systems with several pathways and states and/ or more than two binding sites should be analysed by extended forms...

A Coincidence Detection Mechanism Controls PX-BAR Domain-Mediated Endocytic Membrane Remodeling via an Allosteric Structural Switch.

Science.gov (United States)

Lo, Wen-Ting; Vujičić Žagar, Andreja; Gerth, Fabian; Lehmann, Martin; Puchkov, Dymtro; Krylova, Oxana; Freund, Christian; Scapozza, Leonardo; Vadas, Oscar; Haucke, Volker

2017-11-20

Clathrin-mediated endocytosis occurs by bending and remodeling of the membrane underneath the coat. Bin-amphiphysin-rvs (BAR) domain proteins are crucial for endocytic membrane remodeling, but how their activity is spatiotemporally controlled is largely unknown. We demonstrate that the membrane remodeling activity of sorting nexin 9 (SNX9), a late-acting endocytic PX-BAR domain protein required for constriction of U-shaped endocytic intermediates, is controlled by an allosteric structural switch involving coincident detection of the clathrin adaptor AP2 and phosphatidylinositol-3,4-bisphosphate (PI(3,4)P 2 ) at endocytic sites. Structural, biochemical, and cell biological data show that SNX9 is autoinhibited in solution. Binding to PI(3,4)P 2 via its PX-BAR domain, and concomitant association with AP2 via sequences in the linker region, releases SNX9 autoinhibitory contacts to enable membrane constriction. Our results reveal a mechanism for restricting the latent membrane remodeling activity of BAR domain proteins to allow spatiotemporal coupling of membrane constriction to the progression of the endocytic pathway. Copyright © 2017 Elsevier Inc. All rights reserved.

Positive allosteric modulation of GABA-A receptors reduces capsaicin-induced primary and secondary hypersensitivity in rats

DEFF Research Database (Denmark)

Hansen, Rikke Rie; Erichsen, Helle K; Brown, David T

2012-01-01

GABA-A receptor positive allosteric modulators (PAMs) mediate robust analgesia in animal models of pathological pain, in part via enhancing injury-induced loss of GABA-A-α2 and -α3 receptor function within the spinal cord. As yet, a lack of clinically suitable tool compounds has prevented this co...

Allosteric Inhibition of Factor XIIIa. Non-Saccharide Glycosaminoglycan Mimetics, but Not Glycosaminoglycans, Exhibit Promising Inhibition Profile.

Directory of Open Access Journals (Sweden)

Rami A Al-Horani

Full Text Available Factor XIIIa (FXIIIa is a transglutaminase that catalyzes the last step in the coagulation process. Orthostery is the only approach that has been exploited to design FXIIIa inhibitors. Yet, allosteric inhibition of FXIIIa is a paradigm that may offer a key advantage of controlled inhibition over orthosteric inhibition. Such an approach is likely to lead to novel FXIIIa inhibitors that do not carry bleeding risks. We reasoned that targeting a collection of basic amino acid residues distant from FXIIIa's active site by using sulfated glycosaminoglycans (GAGs or non-saccharide GAG mimetics (NSGMs would lead to the discovery of the first allosteric FXIIIa inhibitors. We tested a library of 22 variably sulfated GAGs and NSGMs against human FXIIIa to discover promising hits. Interestingly, although some GAGs bound to FXIIIa better than NSGMs, no GAG displayed any inhibition. An undecasulfated quercetin analog was found to inhibit FXIIIa with reasonable potency (efficacy of 98%. Michaelis-Menten kinetic studies revealed an allosteric mechanism of inhibition. Fluorescence studies confirmed close correspondence between binding affinity and inhibition potency, as expected for an allosteric process. The inhibitor was reversible and at least 9-fold- and 26-fold selective over two GAG-binding proteins factor Xa (efficacy of 71% and thrombin, respectively, and at least 27-fold selective over a cysteine protease papain. The inhibitor also inhibited the FXIIIa-mediated polymerization of fibrin in vitro. Overall, our work presents the proof-of-principle that FXIIIa can be allosterically modulated by sulfated non-saccharide agents much smaller than GAGs, which should enable the design of selective and safe anticoagulants.

Hotspot mutations in KIT receptor differentially modulate its allosterically coupled conformational dynamics: impact on activation and drug sensitivity.

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Isaure Chauvot de Beauchêne

2014-07-01

Full Text Available Receptor tyrosine kinase KIT controls many signal transduction pathways and represents a typical allosterically regulated protein. The mutation-induced deregulation of KIT activity impairs cellular physiological functions and causes serious human diseases. The impact of hotspots mutations (D816H/Y/N/V and V560G/D localized in crucial regulatory segments, the juxtamembrane region (JMR and the activation (A- loop, on KIT internal dynamics was systematically studied by molecular dynamics simulations. The mutational outcomes predicted in silico were correlated with in vitro and in vivo activation rates and drug sensitivities of KIT mutants. The allosteric regulation of KIT in the native and mutated forms is described in terms of communication between the two remote segments, JMR and A-loop. A strong correlation between the communication profile and the structural and dynamical features of KIT in the native and mutated forms was established. Our results provide new insight on the determinants of receptor KIT constitutive activation by mutations and resistance of KIT mutants to inhibitors. Depiction of an intra-molecular component of the communication network constitutes a first step towards an integrated description of vast communication pathways established by KIT in physiopathological contexts.

Emerging Computational Methods for the Rational Discovery of Allosteric Drugs.

Science.gov (United States)

Wagner, Jeffrey R; Lee, Christopher T; Durrant, Jacob D; Malmstrom, Robert D; Feher, Victoria A; Amaro, Rommie E

2016-06-08

Allosteric drug development holds promise for delivering medicines that are more selective and less toxic than those that target orthosteric sites. To date, the discovery of allosteric binding sites and lead compounds has been mostly serendipitous, achieved through high-throughput screening. Over the past decade, structural data has become more readily available for larger protein systems and more membrane protein classes (e.g., GPCRs and ion channels), which are common allosteric drug targets. In parallel, improved simulation methods now provide better atomistic understanding of the protein dynamics and cooperative motions that are critical to allosteric mechanisms. As a result of these advances, the field of predictive allosteric drug development is now on the cusp of a new era of rational structure-based computational methods. Here, we review algorithms that predict allosteric sites based on sequence data and molecular dynamics simulations, describe tools that assess the druggability of these pockets, and discuss how Markov state models and topology analyses provide insight into the relationship between protein dynamics and allosteric drug binding. In each section, we first provide an overview of the various method classes before describing relevant algorithms and software packages.

The allosteric site regulates the voltage sensitivity of muscarinic receptors.

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Hoppe, Anika; Marti-Solano, Maria; Drabek, Matthäus; Bünemann, Moritz; Kolb, Peter; Rinne, Andreas

2018-01-01

Muscarinic receptors (M-Rs) for acetylcholine (ACh) belong to the class A of G protein-coupled receptors. M-Rs are activated by orthosteric agonists that bind to a specific site buried in the M-R transmembrane helix bundle. In the active conformation, receptor function can be modulated either by allosteric modulators, which bind to the extracellular receptor surface or by the membrane potential via an unknown mechanism. Here, we compared the modulation of M 1 -Rs and M 3 -Rs induced by changes in voltage to their allosteric modulation by chemical compounds. We quantified changes in receptor signaling in single HEK 293 cells with a FRET biosensor for the G q protein cycle. In the presence of ACh, M 1 -R signaling was potentiated by voltage, similarly to positive allosteric modulation by benzyl quinolone carboxylic acid. Conversely, signaling of M 3 -R was attenuated by voltage or the negative allosteric modulator gallamine. Because the orthosteric site is highly conserved among M-Rs, but allosteric sites vary, we constructed "allosteric site" M 3 /M 1 -R chimeras and analyzed their voltage dependencies. Exchanging the entire allosteric sites eliminated the voltage sensitivity of ACh responses for both receptors, but did not affect their modulation by allosteric compounds. Furthermore, a point mutation in M 3 -Rs caused functional uncoupling of the allosteric and orthosteric sites and abolished voltage dependence. Molecular dynamics simulations of the receptor variants indicated a subtype-specific crosstalk between both sites, involving the conserved tyrosine lid structure of the orthosteric site. This molecular crosstalk leads to receptor subtype-specific voltage effects. Copyright © 2017 Elsevier Inc. All rights reserved.

Intergenerational transmission of educational attainment: Three levels of parent-child communication as mediators.

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Chi, Liping

2013-04-01

Although the intergenerational transmission of educational attainment has been confirmed by many researchers, its mechanism still remains controversial. Parent-child communication has been regarded as one of the important mediators. The present study primarily aimed to examine the potentially mediating role of parent-child communication in the transmission of educational attainment, based on a sample of 366 Chinese fifth and sixth graders. Parent-child communication was measured against the three levels of the parents' communication ability, the quality of the father-child and mother-child communications, and the relation between the two dyadic communications. The results duplicated the positive effect of parents' educational attainment on children's academic achievement. Moreover, it was found that parents' communication ability alone played a mediating role, and that the three levels of parent-child communication constructed a "mediator chain" between the parents' educational attainment and the children's academic achievement. Finally, the intergenerational transmission of educational attainment in China and the mediating role of the three levels of parent-child communication were discussed. © 2012 The Institute of Psychology, Chinese Academy of Sciences and Blackwell Publishing Asia Pty Ltd.

Computer Mediated Communication and the Emergence of "Electronic Opportunism"

OpenAIRE

Rocco, Elena; Warglien, Massimo

1996-01-01

An experiment on how communication affects cooperation in a social dilemma shows that computer mediated communication (CMC) and face to face communication have markedly different effects on patterns of collective behavior. While face to face communication sustains stable cooperation, CMC makes cooperative agreements in groups extremely fragile, giving rise to waves of opportunistic behavior. Further analysis of communication protocols highlights that the breakdown of ordinary communication ru...

An evolution-based strategy for engineering allosteric regulation

Science.gov (United States)

Pincus, David; Resnekov, Orna; Reynolds, Kimberly A.

2017-04-01

Allosteric regulation provides a way to control protein activity at the time scale of milliseconds to seconds inside the cell. An ability to engineer synthetic allosteric systems would be of practical utility for the development of novel biosensors, creation of synthetic cell signaling pathways, and design of small molecule pharmaceuticals with regulatory impact. To this end, we outline a general approach—termed rational engineering of allostery at conserved hotspots (REACH)—to introduce novel regulation into a protein of interest by exploiting latent allostery that has been hard-wired by evolution into its structure. REACH entails the use of statistical coupling analysis (SCA) to identify ‘allosteric hotspots’ on protein surfaces, the development and implementation of experimental assays to test hotspots for functionality, and a toolkit of allosteric modulators to impinge on endogenous cellular circuitry. REACH can be broadly applied to rewire cellular processes to respond to novel inputs.

Allosteric Inhibition of Macrophage Migration Inhibitory Factor Revealed by Ibudilast

Energy Technology Data Exchange (ETDEWEB)

Cho, Y.; Crichlow, G; Vermeire, J; Leng, L; Du, X; Hodsdon, M; Bucala, R; Cappello, M; Gross, M; et al.

2010-01-01

AV411 (ibudilast; 3-isobutyryl-2-isopropylpyrazolo-[1,5-a]pyridine) is an antiinflammatory drug that was initially developed for the treatment of bronchial asthma but which also has been used for cerebrovascular and ocular indications. It is a nonselective inhibitor of various phosphodiesterases (PDEs) and has varied antiinflammatory activity. More recently, AV411 has been studied as a possible therapeutic for the treatment of neuropathic pain and opioid withdrawal through its actions on glial cells. As described herein, the PDE inhibitor AV411 and its PDE-inhibition-compromised analog AV1013 inhibit the catalytic and chemotactic functions of the proinflammatory protein, macrophage migration inhibitory factor (MIF). Enzymatic analysis indicates that these compounds are noncompetitive inhibitors of the p-hydroxyphenylpyruvate (HPP) tautomerase activity of MIF and an allosteric binding site of AV411 and AV1013 is detected by NMR. The allosteric inhibition mechanism is further elucidated by X-ray crystallography based on the MIF/AV1013 binary and MIF/AV1013/HPP ternary complexes. In addition, our antibody experiments directed against MIF receptors indicate that CXCR2 is the major receptor for MIF-mediated chemotaxis of peripheral blood mononuclear cells.

Mediated Intercultural Communication Barrier in No Drama Zone! Group

OpenAIRE

Lizal, Valentino

2015-01-01

This research study aimed to describe the mediated intercultural communication barriers in the No Drama Zone! group. This study is a qualitative descriptive type of research, with case study method. By doing in depth interview and observation, researcher found two barriers that generates other barriers in the group's mediated intercultural communication. The two big barriers were: language and physical barriers. Language barriers in this group generated two barriers, emotional barrier and pe...

Allosteric communication in myosin V: from small conformational changes to large directed movements.

Directory of Open Access Journals (Sweden)

M Cecchini

Full Text Available The rigor to post-rigor transition in myosin, a consequence of ATP binding, plays an essential role in the Lymn-Taylor functional cycle because it results in the dissociation of the actomyosin complex after the powerstroke. On the basis of the X-ray structures of myosin V, we have developed a new normal mode superposition model for the transition path between the two states. Rigid-body motions of the various subdomains and specific residues at the subdomain interfaces are key elements in the transition. The allosteric communication between the nucleotide binding site and the U50/L50 cleft is shown to result from local changes due to ATP binding, which induce large amplitude motions that are encoded in the structure of the protein. The triggering event is the change in the interaction of switch I and the P-loop, which is stabilized by ATP binding. The motion of switch I, which is a relatively rigid element of the U50 subdomain, leads directly to a partial opening of the U50/L50 cleft; the latter is expected to weaken the binding of myosin to actin. The calculated transition path demonstrates the nature of the subdomain coupling and offers an explanation for the mutual exclusion of ATP and actin binding. The mechanism of the uncoupling of the converter from the motor head, an essential part of the transition, is elucidated. The origin of the partial untwisting of the central beta-sheet in the rigor to post-rigor transition is described.

The formation of group norms in computer-mediated communication

NARCIS (Netherlands)

Postmes, T; Spears, R; Lea, M

The formation of group norms in computer-mediated communication (CMC) was examined among students who used e-mail as part of a course. A network analysis of group structures revealed that (a) content and form of communication is normative, group norms defining communication patterns within groups,

A case study on support for students' thinking through computer-mediated communication.

Science.gov (United States)

Sannomiya, M; Kawaguchi, A

2000-08-01

This is a case study on support for thinking through computer-mediated communication. Two graduate students were supervised in their research using computer-mediated communication, which was asynchronous and written; the supervisor was not present. The students' reports pointed out there was more planning and editing and low interactivity in this approach relative to face-to-face communication. These attributes were confirmed by their supervisor's report. The students also suggested that the latter was effective in support of a production stage of thinking in research, while the former approach was effective in support of examination of thinking. For distance education to be successful, an appropriate combination of communication media must consider students' thinking stages. Finally, transient and permanent effects should be discriminated in computer-mediated communication.

Learners' Willingness to Communicate in Face-to-Face versus Oral Computer-Mediated Communication

Science.gov (United States)

Yanguas, Íñigo; Flores, Alayne

2014-01-01

The present study had two main goals: to explore performance differences in a task-based environment between face-to-face (FTF) and oral computer-mediated communication (OCMC) groups, and to investigate the relationship between trait-like willingness to communicate (WTC) and performance in the FTF and OCMC groups. Students from two intact…

Gender Differences: An Examination of Computer-Mediated Communication.

Science.gov (United States)

Gregory, Mona Y.

Computer-mediated communication (CMC) is a pervasive means of communicating in work place, education, and home settings. Males currently occupy approximately 69% of all jobs in the computer industry and only 10% of upper-level positions are occupied by females. Stereotypical perceptions and gendered occupations contribute to the lack of females in…

The role of emotion in computer-mediated communication: A review

NARCIS (Netherlands)

Derks, D.; Fischer, A.H.; Bos, A.E.R.

2008-01-01

It has been argued that the communication of emotions is more difficult in computer-mediated communication (CMC) than in face-to-face (F2F) communication. The aim of this paper is to review the empirical evidence in order to gain insight in whether emotions are communicated differently in these

In Vivo Investigation of Escitalopram’s Allosteric Site on the Serotonin Transporter

Science.gov (United States)

Murray, Karen E.; Ressler, Kerry J.; Owens, Michael J.

2015-01-01

Escitalopram is a commonly prescribed antidepressant of the selective serotonin reuptake inhibitor class. Clinical evidence and mapping of the serotonin transporter (SERT) identified that escitalopram, in addition to its binding to a primary uptake-blocking site, is capable of binding to the SERT via an allosteric site that is hypothesized to alter escitalopram’s kinetics at the SERT. The studies reported here examined the in vivo role of the SERT allosteric site in escitalopram action. A knockin mouse model that possesses an allosteric-null SERT was developed. Autoradiographic studies indicated that the knockin protein was expressed at a lower density than endogenous mouse SERT (approximately 10–30% of endogenous mouse SERT), but the knockin mice are a viable tool to study the allosteric site. Microdialysis studies in the ventral hippocampus found no measurable decrease in extracellular serotonin response after local escitalopram challenge in mice without the allosteric site compared to mice with the site (p = 0.297). In marble burying assays there was a modest effect of the absence of the allosteric site, with a larger systemic dose of escitalopram (10-fold) necessary for the same effect as in mice with intact SERT (p = 0.023). However, there was no effect of the allosteric site in the tail suspension test. Together these data suggest that there may be a regional specificity in the role of the allosteric site. The lack of a robust effect overall suggests that the role of the allosteric site for escitalopram on the SERT may not produce meaningful in vivo effects. PMID:26621784

Non equivalence of the chains in the allosteric interaction of the hemoglobin

International Nuclear Information System (INIS)

Jacchieri, S.G.

1983-01-01

The importance, for the temperature dependence of the cooperative behaviour of hemoglobin, of the functional non equivalence of the polypeptide chains from which the hemoglobin molecule is built is studied. With such purpose thermodynamic allosteric parameters are introduced called 'mean allosteric parameters' which relate the last two oxygen bindings to the firsttwo ones. It is shown that the mean allosteric free energy is strongly correlated to the Hill parameter which is a classic measure of cooperativity; hence, the mean allosteric free energy measures the hemoglobin cooperativity. Recent experimental data show that the mean allosteric free energy decreasses with temperature; this is due to the mean allosteric enthalphy and entropy being positive quantities. To analise such behaviour in terms of thermodynamic's arguments equations are derived for the thermodynamic parameters of oxygen binding to hemoglobin in terms of those of its chains. Since the obtained equations have a great number of terms the same treatment is applied to a hypothetic dimer from which simpler relations are derived. From both cases it is concluded that the positive character of the mean allosteric enthalpy and entropy is due to the presence of cooperative and anticooperative terms. Since the last terms are absent in the equations of allosteric homoproteins, the characteristic temperature-dependence of hemoglobin's cooperativity depends on the presence of non-equivalent chains. (Author) [pt

Discovery of a novel allosteric modulator of 5-HT3 receptor

DEFF Research Database (Denmark)

Trattnig, Sarah M; Harpsøe, Kasper; Thygesen, Sarah B

2012-01-01

The ligand-gated ion channels in the Cysloop receptor superfamily mediate the effects of neurotransmitters acetylcholine, serotonin, GABA and glycine. Cysloop receptor signaling is susceptible to modulation by ligands acting through numerous allosteric sites. Here we report the discovery of a novel...... receptor guided by a homology model, PU02 is demonstrated to act through a transmembrane intersubunit site situated in the upper three helical turns of TM2 and TM3 in the (+)subunit and TM1 and TM2 in the (minus)subunit. The Ser248, Leu288, Ile290, Thr294 and Gly306 residues are identified as important...

Synchronous Computer-Mediated Communication and Interaction

Science.gov (United States)

Ziegler, Nicole

2016-01-01

The current study reports on a meta-analysis of the relative effectiveness of interaction in synchronous computer-mediated communication (SCMC) and face-to-face (FTF) contexts. The primary studies included in the analysis were journal articles and dissertations completed between 1990 and 2012 (k = 14). Results demonstrate that interaction in SCMC…

Teaching Responsibly with Technology-Mediated Communication

Science.gov (United States)

Veltsos, Jennifer R.; Veltsos, Christophe

2010-01-01

Technology-mediated communication, or "new media," such as blogs, Twitter, wikis, and social network sites, can be an endless source of ideas for activities or inspiration for classroom discussion. Many instructors ask students to monitor current events by following keywords and industry leaders on Twitter and reading both corporate and…

An experimental test of processes underlying self-disclosure in computer-mediated communication

NARCIS (Netherlands)

Schouten, A.P.; Valkenburg, P.M.; Peter, J.

2009-01-01

A consistent finding in computer-mediated communication (CMC) and Internet research is that, compared to face-toface communication, CMC results in higher levels of self-disclosure. We identified four possible mediators that may carry the influence of CMC on self-disclosure: self-presentation,

Allosteric ligands and their binding sites define γ-aminobutyric acid (GABA) type A receptor subtypes.

Science.gov (United States)

Olsen, Richard W

2015-01-01

GABAA receptors (GABA(A)Rs) mediate rapid inhibitory transmission in the brain. GABA(A)Rs are ligand-gated chloride ion channel proteins and exist in about a dozen or more heteropentameric subtypes exhibiting variable age and brain regional localization and thus participation in differing brain functions and diseases. GABA(A)Rs are also subject to modulation by several chemotypes of allosteric ligands that help define structure and function, including subtype definition. The channel blocker picrotoxin identified a noncompetitive channel blocker site in GABA(A)Rs. This ligand site is located in the transmembrane channel pore, whereas the GABA agonist site is in the extracellular domain at subunit interfaces, a site useful for low energy coupled conformational changes of the functional channel domain. Two classes of pharmacologically important allosteric modulatory ligand binding sites reside in the extracellular domain at modified agonist sites at other subunit interfaces: the benzodiazepine site and the high-affinity, relevant to intoxication, ethanol site. The benzodiazepine site is specific for certain GABA(A)R subtypes, mainly synaptic, while the ethanol site is found at a modified benzodiazepine site on different, extrasynaptic, subtypes. In the transmembrane domain are allosteric modulatory ligand sites for diverse chemotypes of general anesthetics: the volatile and intravenous agents, barbiturates, etomidate, propofol, long-chain alcohols, and neurosteroids. The last are endogenous positive allosteric modulators. X-ray crystal structures of prokaryotic and invertebrate pentameric ligand-gated ion channels, and the mammalian GABA(A)R protein, allow homology modeling of GABA(A)R subtypes with the various ligand sites located to suggest the structure and function of these proteins and their pharmacological modulation. © 2015 Elsevier Inc. All rights reserved.

The allosteric behavior of Fur mediates oxidative stress signal transduction in Helicobacter pylori

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Simone ePelliciari

2015-08-01

Full Text Available The microaerophilic gastric pathogen Helicobacter pylori is exposed to oxidative stress originating from the aerobic environment, the oxidative burst of phagocytes and the formation of reactive oxygen species, catalyzed by iron excess. Accordingly, the expression of genes involved in oxidative stress defense have been repeatedly linked to the ferric uptake regulator Fur. Moreover, mutations in the Fur protein affect the resistance to metronidazole, likely due to loss-of-function in the regulation of genes involved in redox control. Although many advances in the molecular understanding of HpFur function were made, little is known about the mechanisms that enable Fur to mediate the responses to oxidative stress.Here we show that iron-inducible, apo-Fur repressed genes, such as pfr and hydA, are induced shortly after oxidative stress, while their oxidative induction is lost in a fur knockout strain. On the contrary, holo-Fur repressed genes, such as frpB1 and fecA1, vary modestly in response to oxidative stress. This indicates that the oxidative stress signal specifically targets apo-Fur repressed genes, rather than impairing indiscriminately the regulatory function of Fur. Footprinting analyses showed that the oxidative signal strongly impairs the binding affinity of Fur towards apo-operators, while the binding towards holo-operators is less affected. Further evidence is presented that a reduced state of Fur is needed to maintain apo-repression, while oxidative conditions shift the preferred binding architecture of Fur towards the holo-operator binding conformation, even in the absence of iron. Together the results demonstrate that the allosteric regulation of Fur enables transduction of oxidative stress signals in H. pylori, supporting the concept that apo-Fur repressed genes can be considered oxidation inducible Fur regulatory targets. These findings may have important implications in the study of H. pylori treatment and resistance to

A3 Adenosine Receptor Allosteric Modulator Induces an Anti-Inflammatory Effect: In Vivo Studies and Molecular Mechanism of Action

Directory of Open Access Journals (Sweden)

Shira Cohen

2014-01-01

Full Text Available The A3 adenosine receptor (A3AR is overexpressed in inflammatory cells and in the peripheral blood mononuclear cells of individuals with inflammatory conditions. Agonists to the A3AR are known to induce specific anti-inflammatory effects upon chronic treatment. LUF6000 is an allosteric compound known to modulate the A3AR and render the endogenous ligand adenosine to bind to the receptor with higher affinity. The advantage of allosteric modulators is their capability to target specifically areas where adenosine levels are increased such as inflammatory and tumor sites, whereas normal body cells and tissues are refractory to the allosteric modulators due to low adenosine levels. LUF6000 administration induced anti-inflammatory effect in 3 experimental animal models of rat adjuvant induced arthritis, monoiodoacetate induced osteoarthritis, and concanavalin A induced liver inflammation in mice. The molecular mechanism of action points to deregulation of signaling proteins including PI3K, IKK, IκB, Jak-2, and STAT-1, resulting in decreased levels of NF-κB, known to mediate inflammatory effects. Moreover, LUF6000 induced a slight stimulatory effect on the number of normal white blood cells and neutrophils. The anti-inflammatory effect of LUF6000, mechanism of action, and the differential effects on inflammatory and normal cells position this allosteric modulator as an attractive and unique drug candidate.

Allosteric regulation of epigenetic modifying enzymes.

Science.gov (United States)

Zucconi, Beth E; Cole, Philip A

2017-08-01

Epigenetic enzymes including histone modifying enzymes are key regulators of gene expression in normal and disease processes. Many drug development strategies to target histone modifying enzymes have focused on ligands that bind to enzyme active sites, but allosteric pockets offer potentially attractive opportunities for therapeutic development. Recent biochemical studies have revealed roles for small molecule and peptide ligands binding outside of the active sites in modulating the catalytic activities of histone modifying enzymes. Here we highlight several examples of allosteric regulation of epigenetic enzymes and discuss the biological significance of these findings. Copyright © 2017 Elsevier Ltd. All rights reserved.

The allosteric switching mechanism in bacteriophage MS2

Energy Technology Data Exchange (ETDEWEB)

Perkett, Matthew R.; Mirijanian, Dina T.; Hagan, Michael F., E-mail: hagan@brandeis.edu [Martin Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02474 (United States)

2016-07-21

We use all-atom simulations to elucidate the mechanisms underlying conformational switching and allostery within the coat protein of the bacteriophage MS2. Assembly of most icosahedral virus capsids requires that the capsid protein adopts different conformations at precise locations within the capsid. It has been shown that a 19 nucleotide stem loop (TR) from the MS2 genome acts as an allosteric effector, guiding conformational switching of the coat protein during capsid assembly. Since the principal conformational changes occur far from the TR binding site, it is important to understand the molecular mechanism underlying this allosteric communication. To this end, we use all-atom simulations with explicit water combined with a path sampling technique to sample the MS2 coat protein conformational transition, in the presence and absence of TR-binding. The calculations find that TR binding strongly alters the transition free energy profile, leading to a switch in the favored conformation. We discuss changes in molecular interactions responsible for this shift. We then identify networks of amino acids with correlated motions to reveal the mechanism by which effects of TR binding span the protein. We find that TR binding strongly affects residues located at the 5-fold and quasi-sixfold interfaces in the assembled capsid, suggesting a mechanism by which the TR binding could direct formation of the native capsid geometry. The analysis predicts amino acids whose substitution by mutagenesis could alter populations of the conformational substates or their transition rates.

Say it with flowers! An fMRI study of object mediated communication

DEFF Research Database (Denmark)

Tylén, Kristian; Wallentin, Mikkel; Roepstorff, Andreas

2009-01-01

Human communicational interaction can be mediated by a host of expressive means from words in a natural language to gestures and material symbols. Given the proper contextual setting even an everyday object can gain a mediating function in a communicational situation. In this study we used event...

Virtual collaboration: face-to-face versus videoconference, audioconference, and computer-mediated communications

Science.gov (United States)

Wainfan, Lynne; Davis, Paul K.

2004-08-01

As we increase our reliance on mediated communication, it is important to be aware the media's influence on group processes and outcomes. A review of 40+ years of research shows that all media-videoconference, audioconference, and computer-mediated communication--change the context of the communication to some extent, reducing cues used to regulate and understand conversation, indicate participants' power and status, and move the group towards agreement. Text-based computer-mediated communication, the "leanest" medum, reduces status effects, domination, and consensus. This has been shown useful in broadening the range of inputs and ideas. However, it has also been shown to increase polarization, deindividuation, and disinhibition, and the time to reach a conclusion. For decision-making tasks, computer-mediated communication can increase choice shift and the likelihood of more risky or extreme decisions. In both videoconference and audioconference, participants cooperate less with linked collaborators, and shift their opinions toward extreme options, compared with face-to-face collaboration. In videoconference and audioconference, local coalitions can form where participants tend to agree more with those in the same room than those on the other end of the line. There is also a tendency in audioconference to disagree with those on the other end of the phone. This paper is a summary of a much more extensive forthcoming report; it reviews the research literature and proposes strategies to leverage the benefits of mediated communication while mitigating its adverse effects.

The associations among computer-mediated communication, relationships, and well-being.

Science.gov (United States)

Schiffrin, Holly; Edelman, Anna; Falkenstern, Melissa; Stewart, Cassandra

2010-06-01

Social support provided by interpersonal relationships is one of the most robust correlates of well-being. Self-disclosure serves as a basic building block of these relationships. With the rapid growth of the Internet in recent years, the question remains how self-disclosure, and subsequently relationships and well-being, differ when people communicate over the Internet rather than in person. The purpose of this article is to describe current Internet usage patterns as well as explore the association of Internet usage and well-being. Additionally, it directly compares the perceived benefits of face-to-face communication and computer-mediated communication. A questionnaire was administered to 99 undergraduates to measure Internet usage patterns, communication partners, self-disclosure, extraversion, and subjective well-being. Although Internet communication was found to be common, individuals perceived computer-mediated communication to be less useful than face-to-face communication. In addition, increased Internet usage was associated with decreased well-being. Implications are discussed in terms of a new Internet paradox in which people increasingly use the Internet for communication, although they perceive it to be less beneficial than face-to-face interactions and it is associated with reduced well-being.

Behind the curtain: cellular mechanisms for allosteric modulation of calcium-sensing receptors

Science.gov (United States)

Cavanaugh, Alice; Huang, Ying; Breitwieser, Gerda E

2012-01-01

Calcium-sensing receptors (CaSR) are integral to regulation of systemic Ca2+ homeostasis. Altered expression levels or mutations in CaSR cause Ca2+ handling diseases. CaSR is regulated by both endogenous allosteric modulators and allosteric drugs, including the first Food and Drug Administration-approved allosteric agonist, Cinacalcet HCl (Sensipar®). Recent studies suggest that allosteric modulators not only alter function of plasma membrane-localized CaSR, but regulate CaSR stability at the endoplasmic reticulum. This brief review summarizes our current understanding of the role of membrane-permeant allosteric agonists in cotranslational stabilization of CaSR, and highlights additional, indirect, signalling-dependent role(s) for membrane-impermeant allosteric drugs. Overall, these studies suggest that allosteric drugs act at multiple cellular organelles to control receptor abundance and hence function, and that drug hydrophobicity can bias the relative contributions of plasma membrane and intracellular organelles to CaSR abundance and signalling. LINKED ARTICLES This article is part of a themed section on the Molecular Pharmacology of G Protein-Coupled Receptors (GPCRs). To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.165.issue-6. To view the 2010 themed section on the same topic visit http://onlinelibrary.wiley.com/doi/10.1111/bph.2010.159.issue-5/issuetoc PMID:21470201

Pair Interactions and Mode of Communication: Comparing Face-to-Face and Computer Mediated Communication

Science.gov (United States)

Tan, Lan Liana; Wigglesworth, Gillian; Storch, Neomy

2010-01-01

In today's second language classrooms, students are often asked to work in pairs or small groups. Such collaboration can take place face-to-face, but now more often via computer mediated communication. This paper reports on a study which investigated the effect of the medium of communication on the nature of pair interaction. The study involved…

Diacylglycerol Acyltransferase 1 Is Regulated by Its N-Terminal Domain in Response to Allosteric Effectors.

Science.gov (United States)

Caldo, Kristian Mark P; Acedo, Jeella Z; Panigrahi, Rashmi; Vederas, John C; Weselake, Randall J; Lemieux, M Joanne

2017-10-01

Diacylglycerol acyltransferase 1 (DGAT1) is an integral membrane enzyme catalyzing the final and committed step in the acyl-coenzyme A (CoA)-dependent biosynthesis of triacylglycerol (TAG). The biochemical regulation of TAG assembly remains one of the least understood areas of primary metabolism to date. Here, we report that the hydrophilic N-terminal domain of Brassica napus DGAT1 (BnaDGAT1 1-113 ) regulates activity based on acyl-CoA/CoA levels. The N-terminal domain is not necessary for acyltransferase activity and is composed of an intrinsically disordered region and a folded segment. We show that the disordered region has an autoinhibitory function and a dimerization interface, which appears to mediate positive cooperativity, whereas the folded segment of the cytosolic region was found to have an allosteric site for acyl-CoA/CoA. Under increasing acyl-CoA levels, the binding of acyl-CoA with this noncatalytic site facilitates homotropic allosteric activation. Enzyme activation, on the other hand, is prevented under limiting acyl-CoA conditions (low acyl-CoA-to-CoA ratio), whereby CoA acts as a noncompetitive feedback inhibitor through interaction with the same folded segment. The three-dimensional NMR solution structure of the allosteric site revealed an α-helix with a loop connecting a coil fragment. The conserved amino acid residues in the loop interacting with CoA were identified, revealing details of this important regulatory element for allosteric regulation. Based on these results, a model is proposed illustrating the role of the N-terminal domain of BnaDGAT1 as a positive and negative modulator of TAG biosynthesis. © 2017 American Society of Plant Biologists. All Rights Reserved.

Exosomes: mediators of communication in eukaryotes

Directory of Open Access Journals (Sweden)

María A Lopez-Verrilli

2013-01-01

Full Text Available In addition to the established mechanisms of intercellular signaling, a new way of communication has gained much attention in the last decade: communication mediated by exosomes. Exosomes are nanovesicles (with a diameter of 40-120 nm secreted into the extracellular space by the multivesicular endosome after its outer membrane fuses with the plasma membrane. Once released, exosomes modulate the response of the recipient cells that recognize them. This indicates that exosomes operate in a specific manner and participate in the regulation of the target cell. Remarkably, exosomes occur from unicellular organisms to mammals, suggesting an evolutionarily conserved mechanism of communication. In this review we describe the cascade of exosome formation, intracellular traffic, secretion, and internalization by recipient cells, and review their most relevant effects. We also highlight important steps that are still poorly understood.

Allosteric Regulation of Proteins

Indian Academy of Sciences (India)

... Lecture Workshops · Refresher Courses · Symposia · Live Streaming. Home; Journals; Resonance – Journal of Science Education; Volume 22; Issue 1. Allosteric Regulation of Proteins: A Historical Perspective on the Development of Concepts and Techniques. General Article Volume 22 Issue 1 January 2017 pp 37-50 ...

Prediction of allosteric sites on protein surfaces with an elastic-network-model-based thermodynamic method.

Science.gov (United States)

Su, Ji Guo; Qi, Li Sheng; Li, Chun Hua; Zhu, Yan Ying; Du, Hui Jing; Hou, Yan Xue; Hao, Rui; Wang, Ji Hua

2014-08-01

Allostery is a rapid and efficient way in many biological processes to regulate protein functions, where binding of an effector at the allosteric site alters the activity and function at a distant active site. Allosteric regulation of protein biological functions provides a promising strategy for novel drug design. However, how to effectively identify the allosteric sites remains one of the major challenges for allosteric drug design. In the present work, a thermodynamic method based on the elastic network model was proposed to predict the allosteric sites on the protein surface. In our method, the thermodynamic coupling between the allosteric and active sites was considered, and then the allosteric sites were identified as those where the binding of an effector molecule induces a large change in the binding free energy of the protein with its ligand. Using the proposed method, two proteins, i.e., the 70 kD heat shock protein (Hsp70) and GluA2 alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor, were studied and the allosteric sites on the protein surface were successfully identified. The predicted results are consistent with the available experimental data, which indicates that our method is a simple yet effective approach for the identification of allosteric sites on proteins.

Interdomain allosteric regulation of Polo kinase by Aurora B and Map205 is required for cytokinesis

Science.gov (United States)

Kachaner, David; Pinson, Xavier; El Kadhi, Khaled Ben; Normandin, Karine; Talje, Lama; Lavoie, Hugo; Lépine, Guillaume; Carréno, Sébastien; Kwok, Benjamin H.; Hickson, Gilles R.

2014-01-01

Drosophila melanogaster Polo and its human orthologue Polo-like kinase 1 fulfill essential roles during cell division. Members of the Polo-like kinase (Plk) family contain an N-terminal kinase domain (KD) and a C-terminal Polo-Box domain (PBD), which mediates protein interactions. How Plks are regulated in cytokinesis is poorly understood. Here we show that phosphorylation of Polo by Aurora B is required for cytokinesis. This phosphorylation in the activation loop of the KD promotes the dissociation of Polo from the PBD-bound microtubule-associated protein Map205, which acts as an allosteric inhibitor of Polo kinase activity. This mechanism allows the release of active Polo from microtubules of the central spindle and its recruitment to the site of cytokinesis. Failure in Polo phosphorylation results in both early and late cytokinesis defects. Importantly, the antagonistic regulation of Polo by Aurora B and Map205 in cytokinesis reveals that interdomain allosteric mechanisms can play important roles in controlling the cellular functions of Plks. PMID:25332165

The Use of Computer-Mediated Communication To Enhance Subsequent Face-to-Face Discussions.

Science.gov (United States)

Dietz-Uhler, Beth; Bishop-Clark, Cathy

2001-01-01

Describes a study of undergraduate students that assessed the effects of synchronous (Internet chat) and asynchronous (Internet discussion board) computer-mediated communication on subsequent face-to-face discussions. Results showed that face-to-face discussions preceded by computer-mediated communication were perceived to be more enjoyable.…

The impact of patient and physician computer mediated communication skill training on reported communication and patient satisfaction.

Science.gov (United States)

Roter, Debra L; Wexler, Randy; Naragon, Phyllis; Forrest, Brian; Dees, Jason; Almodovar, Astrid; Wood, Julie

2012-09-01

The objective was to evaluate parallel patient and physician computer-mediated communication skill training on participants' report of skill use and patient satisfaction. Separate patient and clinician web-tools comprised of over 500, 10-s video clips demonstrating patient-centered skills in various ways. Four clinician members of the American Academy of Family Physicians National Research Network participated by enrolling 194 patients into a randomized patient trial and 29 physicians into a non-randomized clinician trial of respective interventions. All participants completed baseline and follow-up self-report measures of visit communication and satisfaction. Intervention patients reported using more skills than controls in five of six skill areas, including identification of problems/concerns, information exchange, treatment adherence, shared decision-making and interpersonal rapport (all ppost intervention, physicians reported using more skills in the same 5 areas (all pCommunication skill training delivered in a computer mediated format had a positive and parallel impact on both patient and clinician reported use of patient-centered communication and in patient satisfaction. Computer-mediated interventions are cost and time effective thereby increasing patient and clinician willingness to undertake training. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Differential effects of CSF-1R D802V and KIT D816V homologous mutations on receptor tertiary structure and allosteric communication.

Directory of Open Access Journals (Sweden)

Priscila Da Silva Figueiredo Celestino Gomes

Full Text Available The colony stimulating factor-1 receptor (CSF-1R and the stem cell factor receptor KIT, type III receptor tyrosine kinases (RTKs, are important mediators of signal transduction. The normal functions of these receptors can be compromised by gain-of-function mutations associated with different physiopatological impacts. Whereas KIT D816V/H mutation is a well-characterized oncogenic event and principal cause of systemic mastocytosis, the homologous CSF-1R D802V has not been identified in human cancers. The KIT D816V oncogenic mutation triggers resistance to the RTK inhibitor Imatinib used as first line treatment against chronic myeloid leukemia and gastrointestinal tumors. CSF-1R is also sensitive to Imatinib and this sensitivity is altered by mutation D802V. Previous in silico characterization of the D816V mutation in KIT evidenced that the mutation caused a structure reorganization of the juxtamembrane region (JMR and facilitated its departure from the kinase domain (KD. In this study, we showed that the equivalent CSF-1R D802V mutation does not promote such structural effects on the JMR despite of a reduction on some key H-bonds interactions controlling the JMR binding to the KD. In addition, this mutation disrupts the allosteric communication between two essential regulatory fragments of the receptors, the JMR and the A-loop. Nevertheless, the mutation-induced shift towards an active conformation observed in KIT D816V is not observed in CSF-1R D802V. The distinct impact of equivalent mutation in two homologous RTKs could be associated with the sequence difference between both receptors in the native form, particularly in the JMR region. A local mutation-induced perturbation on the A-loop structure observed in both receptors indicates the stabilization of an inactive non-inhibited form, which Imatinib cannot bind.

Differential Effects of CSF-1R D802V and KIT D816V Homologous Mutations on Receptor Tertiary Structure and Allosteric Communication

Science.gov (United States)

Da Silva Figueiredo Celestino Gomes, Priscila; Panel, Nicolas; Laine, Elodie; Pascutti, Pedro Geraldo; Solary, Eric; Tchertanov, Luba

2014-01-01

The colony stimulating factor-1 receptor (CSF-1R) and the stem cell factor receptor KIT, type III receptor tyrosine kinases (RTKs), are important mediators of signal transduction. The normal functions of these receptors can be compromised by gain-of-function mutations associated with different physiopatological impacts. Whereas KIT D816V/H mutation is a well-characterized oncogenic event and principal cause of systemic mastocytosis, the homologous CSF-1R D802V has not been identified in human cancers. The KIT D816V oncogenic mutation triggers resistance to the RTK inhibitor Imatinib used as first line treatment against chronic myeloid leukemia and gastrointestinal tumors. CSF-1R is also sensitive to Imatinib and this sensitivity is altered by mutation D802V. Previous in silico characterization of the D816V mutation in KIT evidenced that the mutation caused a structure reorganization of the juxtamembrane region (JMR) and facilitated its departure from the kinase domain (KD). In this study, we showed that the equivalent CSF-1R D802V mutation does not promote such structural effects on the JMR despite of a reduction on some key H-bonds interactions controlling the JMR binding to the KD. In addition, this mutation disrupts the allosteric communication between two essential regulatory fragments of the receptors, the JMR and the A-loop. Nevertheless, the mutation-induced shift towards an active conformation observed in KIT D816V is not observed in CSF-1R D802V. The distinct impact of equivalent mutation in two homologous RTKs could be associated with the sequence difference between both receptors in the native form, particularly in the JMR region. A local mutation-induced perturbation on the A-loop structure observed in both receptors indicates the stabilization of an inactive non-inhibited form, which Imatinib cannot bind. PMID:24828813

Piroxicam inhibits NMDA receptor-mediated excitotoxicity through allosteric inhibition of the GluN2B subunit: an in silico study elucidating a novel mechanism of action of the drug.

Science.gov (United States)

Mazumder, Muhammed Khairujjaman; Borah, Anupom

2014-12-01

Hyperactivation of GluN2B subunit containing N-methyl-d-aspartate receptors (NMDARs) significantly contributes to the development of several neurodegenerative diseases through a process called excitotoxicity. NMDARs are voltage-gated Ca2+ channels which when activated lead to excessive influx of Ca2+ into neurons thereby exacerbating several calcium-dependent pathways that cause oxidative stress and apoptosis. Several drugs are presently in use to counter the NMDAR-mediated excitotoxic events among which Ifenprodil and its derivatives are GluN2B selective allosteric antagonists. Certain non-steroidal anti-inflammatory drugs (NSAIDs) have also been reported to inhibit NMDARs and the resultant pathologies. Meanwhile, Piroxicam, which is a NSAID, has been reported to be protective in cerebral ischemia-induced neurodegeneration through various pathways. Since Piroxicam has more number of interacting groups as compared to other NSAIDs and also has structural similarities with Ifenprodil, we thought it prudent that Piroxicam may inhibit NMDARs similar to Ifenprodil. By using molecular docking as a tool, we validated the hypothesis and hereby report for the first time that Piroxicam can inhibit GluN2B containing NMDARs through allosteric mode similar to the well known selective antagonist--Ifenprodil; and thus can be a therapeutic drug for the prevention of excitotoxic neurodegeneration. Copyright © 2014 Elsevier Ltd. All rights reserved.

Intrasteric control of AMPK via the gamma1 subunit AMP allosteric regulatory site.

Science.gov (United States)

Adams, Julian; Chen, Zhi-Ping; Van Denderen, Bryce J W; Morton, Craig J; Parker, Michael W; Witters, Lee A; Stapleton, David; Kemp, Bruce E

2004-01-01

AMP-activated protein kinase (AMPK) is a alphabetagamma heterotrimer that is activated in response to both hormones and intracellular metabolic stress signals. AMPK is regulated by phosphorylation on the alpha subunit and by AMP allosteric control previously thought to be mediated by both alpha and gamma subunits. Here we present evidence that adjacent gamma subunit pairs of CBS repeat sequences (after Cystathionine Beta Synthase) form an AMP binding site related to, but distinct from the classical AMP binding site in phosphorylase, that can also bind ATP. The AMP binding site of the gamma(1) CBS1/CBS2 pair, modeled on the structures of the CBS sequences present in the inosine monophosphate dehydrogenase crystal structure, contains three arginine residues 70, 152, and 171 and His151. The yeast gamma homolog, snf4 contains a His151Gly substitution, and when this is introduced into gamma(1), AMP allosteric control is substantially lost and explains why the yeast snf1p/snf4p complex is insensitive to AMP. Arg70 in gamma(1) corresponds to the site of mutation in human gamma(2) and pig gamma(3) genes previously identified to cause an unusual cardiac phenotype and glycogen storage disease, respectively. Mutation of any of AMP binding site Arg residues to Gln substantially abolishes AMP allosteric control in expressed AMPK holoenzyme. The Arg/Gln mutations also suppress the previously described inhibitory properties of ATP and render the enzyme constitutively active. We propose that ATP acts as an intrasteric inhibitor by bridging the alpha and gamma subunits and that AMP functions to derepress AMPK activity.

A small-molecule allosteric inhibitor of Mycobacterium tuberculosis tryptophan synthase

Energy Technology Data Exchange (ETDEWEB)

Wellington, Samantha; Nag, Partha P.; Michalska, Karolina; Johnston, Stephen E.; Jedrzejczak, Robert P.; Kaushik, Virendar K.; Clatworthy, Anne E.; Siddiqi, Noman; McCarren, Patrick; Bajrami, Besnik; Maltseva, Natalia I.; Combs, Senya; Fisher, Stewart L.; Joachimiak, Andrzej; Schreiber, Stuart L.; Hung, Deborah T.

2017-07-03

New antibiotics with novel targets are greatly needed. Bacteria have numerous essential functions, but only a small fraction of such processes—primarily those involved in macromolecular synthesis—are inhibited by current drugs. Targeting metabolic enzymes has been the focus of recent interest, but effective inhibitors have been difficult to identify. We describe a synthetic azetidine derivative, BRD4592, that kills Mycobacterium tuberculosis (Mtb) through allosteric inhibition of tryptophan synthase (TrpAB), a previously untargeted, highly allosterically regulated enzyme. BRD4592 binds at the TrpAB a–b-subunit interface and affects multiple steps in the enzyme’s overall reaction, resulting in inhibition not easily overcome by changes in metabolic environment. We show that TrpAB is required for the survival of Mtb and Mycobacterium marinum in vivo and that this requirement may be independent of an adaptive immune response. This work highlights the effectiveness of allosteric inhibition for targeting proteins that are naturally highly dynamic and that are essential in vivo, despite their apparent dispensability under in vitro conditions, and suggests a framework for the discovery of a next generation of allosteric inhibitors.

Collaborative Dialogue in Synchronous Computer-Mediated Communication and Face-to-Face Communication

Science.gov (United States)

Zeng, Gang

2017-01-01

Previous research has documented that collaborative dialogue promotes L2 learning in both face-to-face (F2F) and synchronous computer-mediated communication (SCMC) modalities. However, relatively little research has explored modality effects on collaborative dialogue. Thus, motivated by sociocultual theory, this study examines how F2F compares…

Mechanism of allosteric regulation of β2-adrenergic receptor by cholesterol

DEFF Research Database (Denmark)

Manna, Moutusi; Niemelä, Miia; Tynkkynen, Joona

2016-01-01

) - a prototypical G protein-coupled receptor - is modulated by cholesterol in an allosteric fashion. Extensive atomistic simulations show that cholesterol regulates b2AR by limiting its conformational variability. The mechanism of action is based on the binding of cholesterol at specific high-affinity sites located...... near the transmembrane helices 5-7 of the receptor. The alternative mechanism, where the β2AR conformation would be modulated by membrane-mediated interactions, plays only a minor role. Cholesterol analogues also bind to cholesterol binding sites and impede the structural flexibility of β2AR, however...... cholesterol generates the strongest effect. The results highlight the capacity of lipids to regulate the conformation of membrane receptors through specific interactions....

Written and Computer-Mediated Accounting Communication Skills: An Employer Perspective

Science.gov (United States)

Jones, Christopher G.

2011-01-01

Communication skills are a fundamental personal competency for a successful career in accounting. What is not so obvious is the specific written communication skill set employers look for and the extent those skills are computer mediated. Using survey research, this article explores the particular skills employers desire and their satisfaction…

Allosteric small-molecule kinase inhibitors

DEFF Research Database (Denmark)

Wu, Peng; Clausen, Mads Hartvig; Nielsen, Thomas E.

2015-01-01

current barriers of kinase inhibitors, including poor selectivity and emergence of drug resistance. In spite of the small number of identified allosteric inhibitors in comparison with that of inhibitors targeting the ATP pocket, encouraging results, such as the FDA-approval of the first small...

Computer-Mediated Communication: A vehicle for learning

Directory of Open Access Journals (Sweden)

Linda D. Grooms

2003-10-01

Full Text Available The axiom of humanity’s basic need to communicate provides the impetus to explore the nature and quality of computer-mediated communication as a vehicle for learning in higher education. This exploratory study examined the experiential communication perceptions of online doctoral students during the infancy of their program. Eighty-five students were electronically queried through a 32 item open-ended questionnaire within a 13 day time frame. Preliminary findings supported the experience of Seagren and Watwood (1996 at the Lincoln Campus of the University of Nebraska, that “more information widens learning opportunities, but without interaction, learning is not enhanced” (p. 514. The overarching implications stress that faculty development and instructional planning are essential for the effective delivery of online courses, and even more so when collaborative learning is used. Facilitating group communication and interaction are areas beckoning attention as we continue to effectively organize the online classroom of this new millennium.

Social attraction in video-mediated communication : The role of nonverbal affiliative behavior

NARCIS (Netherlands)

Croes, Emmelyn; Antheunis, Marjolijn; Schouten, Alexander; Krahmer, Emiel

2018-01-01

The first aim of this study was to analyze video-mediated communication (VMC), in comparison to face-to-face (FTF) communication, and the effect it has on how communicators express nonverbal affiliative behaviors relevant for social attraction. Second, this study aimed to discover whether these

A small-molecule allosteric inhibitor of Mycobacterium tuberculosis tryptophan synthase

Energy Technology Data Exchange (ETDEWEB)

Wellington, Samantha; Nag, Partha P.; Michalska, Karolina; Johnston, Stephen E.; Jedrzejczak, Robert P.; Kaushik, Virendar K.; Clatworthy, Anne E.; Siddiqi, Noman; McCarren, Patrick; Bajrami, Besnik; Maltseva, Natalia I.; Combs, Senya; Fisher, Stewart L.; Joachimiak, Andrzej; Schreiber, Stuart L.; Hung, Deborah T.

2017-07-03

New antibiotics with novel targets are greatly needed. Bacteria have numerous essential functions, but only a small fraction of such processes—primarily those involved in macromolecular synthesis—are inhibited by current drugs. Targeting metabolic enzymes has been the focus of recent interest, but effective inhibitors have been difficult to identify. We describe a synthetic azetidine derivative, BRD4592, that kills Mycobacterium tuberculosis (Mtb) through allosteric inhibition of tryptophan synthase (TrpAB), a previously untargeted, highly allosterically regulated enzyme. BRD4592 binds at the TrpAB α–β-subunit interface and affects multiple steps in the enzyme's overall reaction, resulting in inhibition not easily overcome by changes in metabolic environment. We show that TrpAB is required for the survival of Mtb and Mycobacterium marinum in vivo and that this requirement may be independent of an adaptive immune response. This work highlights the effectiveness of allosteric inhibition for targeting proteins that are naturally highly dynamic and that are essential in vivo, despite their apparent dispensability under in vitro conditions, and suggests a framework for the discovery of a next generation of allosteric inhibitors.

Sex differences in perceived attributes of computer-mediated communication.

Science.gov (United States)

Harper, Vernon B

2003-02-01

Researchers have pointed to the influence of sex with respect to the attributes of the computer medium. The author elaborates upon possible sex differences in reference to perceived attributes of the computer medium, i.e., Richness, Accessibility, Velocity, Interactivity, Plasticity, and Immediacy. Data from both a pilot and main study are reported and interpreted. The pilot study included 78 participants, while the main study involved 211. The independent samples were composed of Communication Studies students enrolled at two Mid-Atlantic universities. Nine items with anchors of 1: strongly disagree and 7: strongly agree were taken from the 2000 Computer Mediated Communication Competence Scale of Spitzberg to assess the attributes of computer-mediated interaction. The results indicate that women scored higher than men on perceptions of Accessibility, Velocity, Interactivity, and Immediacy.

Child-Mediated Stroke Communication: findings from Hip Hop Stroke.

Science.gov (United States)

Williams, Olajide; DeSorbo, Alexandra; Noble, James; Gerin, William

2012-01-01

Low thrombolysis rates for acute ischemic stroke are linked to delays in seeking immediate treatment due to low public stroke awareness. We aimed to assess whether "Child-Mediated Stroke Communication" could improve stroke literacy of parents of children enrolled in a school-based stroke literacy program called Hip Hop Stroke. Parents of children aged 9 to 12 years from 2 public schools in Harlem, New York City, were recruited to participate in stroke literacy questionnaires before and after their child's participation in Hip Hop Stroke, a novel Child-Mediated Stroke Communication intervention delivered in school auditoriums. Parental recall of stroke information communicated through their child was assessed 1-week after the intervention. Fifth and sixth grade students (n=182) were enrolled into Hip Hop Stroke. One hundred two parents were approached in person to participate; 75 opted to participate and 71 completed both the pretest and post-test (74% response rate and 95% retention rate). Parental stroke literacy improved after the program; before the program, 3 parents of 75 (3.9%) were able to identify the 5 cardinal stroke symptoms, distracting symptom (chest pains), and had an urgent action plan (calling 911) compared with 21 of 71 parents (29.6%) postintervention (P<0.001). The FAST mnemonic was known by 2 (2.7%) of participants before the program versus 29 (41%) after program completion (P<0.001). Knowledge of stroke signs and symptoms remains low among residents of this high-risk population. The use of Child-Mediated Stroke Communication suggests that school children aged 9 to 12 years may be effective conduits of critical stroke knowledge to their parents.

Scalable rule-based modelling of allosteric proteins and biochemical networks.

Directory of Open Access Journals (Sweden)

Julien F Ollivier

2010-11-01

Full Text Available Much of the complexity of biochemical networks comes from the information-processing abilities of allosteric proteins, be they receptors, ion-channels, signalling molecules or transcription factors. An allosteric protein can be uniquely regulated by each combination of input molecules that it binds. This "regulatory complexity" causes a combinatorial increase in the number of parameters required to fit experimental data as the number of protein interactions increases. It therefore challenges the creation, updating, and re-use of biochemical models. Here, we propose a rule-based modelling framework that exploits the intrinsic modularity of protein structure to address regulatory complexity. Rather than treating proteins as "black boxes", we model their hierarchical structure and, as conformational changes, internal dynamics. By modelling the regulation of allosteric proteins through these conformational changes, we often decrease the number of parameters required to fit data, and so reduce over-fitting and improve the predictive power of a model. Our method is thermodynamically grounded, imposes detailed balance, and also includes molecular cross-talk and the background activity of enzymes. We use our Allosteric Network Compiler to examine how allostery can facilitate macromolecular assembly and how competitive ligands can change the observed cooperativity of an allosteric protein. We also develop a parsimonious model of G protein-coupled receptors that explains functional selectivity and can predict the rank order of potency of agonists acting through a receptor. Our methodology should provide a basis for scalable, modular and executable modelling of biochemical networks in systems and synthetic biology.

Intergroup differentiation in computer-mediated communication : Effects of depersonalization

NARCIS (Netherlands)

Postmes, T; Spears, R; Lea, M

Two studies examined intergroup discussions via computer-mediated communication systems. It was hypothesized that depersonalization, in comparison with individuated interaction, would increase the tendency for intergroup differentiation in attitudes and stereotypes, In Study 1, 24 groups

Exploring web-mediated communication: A genre-based linguistic study for new

Science.gov (United States)

Zummo, Marianna Lya

2015-01-01

This paper questions the nature of the communicative event that takes place in online contexts between doctors and web-users, showing computer-mediated linguistic norms and discussing the nature of the participants’ roles. Based on an analysis of 1005 posts occurring between doctors and the users of health service websites, I analyse how doctor–patient communication is affected by the medium and how health professionals overcome issues concerning the virtual medical visit. Results suggest that (a) online medical answers offer a different service from that expected by users, as doctors cannot always fulfill patient requests, and (b) net consultations use aspects of traditional doctor–patient exchange and yet present a language and a style that are affected by the computer-mediated environment. Additionally, it seems that this new form leads to a different model of doctor–patient relationship. The findings are intended to provide new insights into web-based discourse in doctor–patient communication and to demonstrate the emergence of a new style in medical communication.

The new media paradigm: From mediation to mediatisation of social communication

Directory of Open Access Journals (Sweden)

Bogdanić Aleksandar

2013-01-01

Full Text Available This study discusses the changes in character and role of social communication at the beginning of the twenty-first century. Beside itself being the subject of most thorough change under the influence of globalization and new communication technologies, communication became a key agency of social change. Mediation is seen as one of the phenomena that dominates everyday life and a common feature of almost all forms of human communication. Certain features of contemporary communication are also analyzed in greater detail, such as the new media and the culture of new 'intermediaries'. The new media, such as the internet, mobile phone, Youtube and Facebook, beside their intermediary nature, share a number of other features which are discussed in the study. The features of the culture of new intermediaries that are, among others, discussed in the study are media, content or user convergence, intertextuality, decentralization and decontextualization, media democratization, communicational reductionism, visual culture domination, new genres, planetary popularity, personal mass communication, commercialization of privacy, hypersensationalism and others. The study concludes that the new media have permeated all pores of society and became the integral part of social structure for the reason of which citizens must adapt to them. The media are not merely the means of social interaction but the place of social interaction. In other words, society and human communication have been mediatized.

Computer-Mediated Communications Systems: Will They Catch On?

Science.gov (United States)

Cook, Dave; Ridley, Michael

1990-01-01

Describes the use of CoSy, a computer conferencing system, by academic librarians at McMaster University in Ontario. Computer-mediated communications systems (CMCS) are discussed, the use of the system for electronic mail and computer conferencing is described, the perceived usefulness of CMCS is examined, and a sidebar explains details of the…

GABAA receptor: Positive and negative allosteric modulators.

Science.gov (United States)

Olsen, Richard W

2018-01-31

gamma-Aminobutyric acid (GABA)-mediated inhibitory neurotransmission and the gene products involved were discovered during the mid-twentieth century. Historically, myriad existing nervous system drugs act as positive and negative allosteric modulators of these proteins, making GABA a major component of modern neuropharmacology, and suggesting that many potential drugs will be found that share these targets. Although some of these drugs act on proteins involved in synthesis, degradation, and membrane transport of GABA, the GABA receptors Type A (GABA A R) and Type B (GABA B R) are the targets of the great majority of GABAergic drugs. This discovery is due in no small part to Professor Norman Bowery. Whereas the topic of GABA B R is appropriately emphasized in this special issue, Norman Bowery also made many insights into GABA A R pharmacology, the topic of this article. GABA A R are members of the ligand-gated ion channel receptor superfamily, a chloride channel family of a dozen or more heteropentameric subtypes containing 19 possible different subunits. These subtypes show different brain regional and subcellular localization, age-dependent expression, and potential for plastic changes with experience including drug exposure. Not only are GABA A R the targets of agonist depressants and antagonist convulsants, but most GABA A R drugs act at other (allosteric) binding sites on the GABA A R proteins. Some anxiolytic and sedative drugs, like benzodiazepine and related drugs, act on GABA A R subtype-dependent extracellular domain sites. General anesthetics including alcohols and neurosteroids act at GABA A R subunit-interface trans-membrane sites. Ethanol at high anesthetic doses acts on GABA A R subtype-dependent trans-membrane domain sites. Ethanol at low intoxicating doses acts at GABA A R subtype-dependent extracellular domain sites. Thus GABA A R subtypes possess pharmacologically specific receptor binding sites for a large group of different chemical classes of

Computer-mediated-communication and social networking tools at work

NARCIS (Netherlands)

Ou, C.X.J.; Sia, C.L.; Hui, C.K.

2013-01-01

Purpose – Advances in information technology (IT) have resulted in the development of various computer‐mediated communication (CMC) and social networking tools. However, quantifying the benefits of utilizing these tools in the organizational context remains a challenge. In this study, the authors

Intersections between the Autism Spectrum and the Internet: Perceived Benefits and Preferred Functions of Computer-Mediated Communication

Science.gov (United States)

Gillespie-Lynch, Kristen; Kapp, Steven K.; Shane-Simpson, Christina; Smith, David Shane; Hutman, Ted

2014-01-01

An online survey compared the perceived benefits and preferred functions of computer-mediated communication of participants with (N = 291) and without ASD (N = 311). Participants with autism spectrum disorder (ASD) perceived benefits of computer-mediated communication in terms of increased comprehension and control over communication, access to…

Allosteric Modulation of Muscarinic Acetylcholine Receptors

Czech Academy of Sciences Publication Activity Database

Jakubík, Jan; El-Fakahany, E. E.

2010-01-01

Roč. 3, č. 9 (2010), s. 2838-2860 ISSN 1424-8247 R&D Projects: GA ČR GA305/09/0681 Institutional research plan: CEZ:AV0Z50110509 Keywords : muscarinic acetylcholine receptors * allosteric modulation * Alzheimer´s disease Subject RIV: CE - Biochemistry

Say it with flowers! An fMRI study of object mediated communication

DEFF Research Database (Denmark)

Tylén, Kristian; Wallentin, Mikkel; Roepstorff, Andreas

2009-01-01

Human communicational interaction can be mediated by a host of expressive means from words in a natural language to gestures and material symbols. Given the proper contextual setting even an everyday object can gain a mediating function in a communicational situation. In this study we used event......-related fMRI to study the brain activity caused by everyday material objects when they are perceived as signals. We found that comprehension of material signals activates bilaterally areas of the ventral stream and pars triangularis of the inferior frontal cortex, that is, areas traditionally associated...

Switch I-dependent allosteric signaling in a G-protein chaperone-B12 enzyme complex.

Science.gov (United States)

Campanello, Gregory C; Lofgren, Michael; Yokom, Adam L; Southworth, Daniel R; Banerjee, Ruma

2017-10-27

G-proteins regulate various processes ranging from DNA replication and protein synthesis to cytoskeletal dynamics and cofactor assimilation and serve as models for uncovering strategies deployed for allosteric signal transduction. MeaB is a multifunctional G-protein chaperone, which gates loading of the active 5'-deoxyadenosylcobalamin cofactor onto methylmalonyl-CoA mutase (MCM) and precludes loading of inactive cofactor forms. MeaB also safeguards MCM, which uses radical chemistry, against inactivation and rescues MCM inactivated during catalytic turnover by using the GTP-binding energy to offload inactive cofactor. The conserved switch I and II signaling motifs used by G-proteins are predicted to mediate allosteric regulation in response to nucleotide binding and hydrolysis in MeaB. Herein, we targeted conserved residues in the MeaB switch I motif to interrogate the function of this loop. Unexpectedly, the switch I mutations had only modest effects on GTP binding and on GTPase activity and did not perturb stability of the MCM-MeaB complex. However, these mutations disrupted multiple MeaB chaperone functions, including cofactor editing, loading, and offloading. Hence, although residues in the switch I motif are not essential for catalysis, they are important for allosteric regulation. Furthermore, single-particle EM analysis revealed, for the first time, the overall architecture of the MCM-MeaB complex, which exhibits a 2:1 stoichiometry. These EM studies also demonstrate that the complex exhibits considerable conformational flexibility. In conclusion, the switch I element does not significantly stabilize the MCM-MeaB complex or influence the affinity of MeaB for GTP but is required for transducing signals between MeaB and MCM. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Allosteric modulation of endogenous metabolites as an avenue for drug discovery.

Science.gov (United States)

Wootten, Denise; Savage, Emilia E; Valant, Celine; May, Lauren T; Sloop, Kyle W; Ficorilli, James; Showalter, Aaron D; Willard, Francis S; Christopoulos, Arthur; Sexton, Patrick M

2012-08-01

G protein-coupled receptors (GPCRs) are the largest family of cell surface receptors and a key drug target class. Recently, allosteric drugs that can co-bind with and modulate the activity of the endogenous ligand(s) for the receptor have become a major focus of the pharmaceutical and biotechnology industry for the development of novel GPCR therapeutic agents. This class of drugs has distinct properties compared with drugs targeting the endogenous (orthosteric) ligand-binding site that include the ability to sculpt cellular signaling and to respond differently in the presence of discrete orthosteric ligands, a behavior termed "probe dependence." Here, using cell signaling assays combined with ex vivo and in vivo studies of insulin secretion, we demonstrate that allosteric ligands can cause marked potentiation of previously "inert" metabolic products of neurotransmitters and peptide hormones, a novel consequence of the phenomenon of probe dependence. Indeed, at the muscarinic M(2) receptor and glucagon-like peptide 1 (GLP-1) receptor, allosteric potentiation of the metabolites, choline and GLP-1(9-36)NH(2), respectively, was ~100-fold and up to 200-fold greater than that seen with the physiological signaling molecules acetylcholine and GLP-1(7-36)NH(2). Modulation of GLP-1(9-36)NH(2) was also demonstrated in ex vivo and in vivo assays of insulin secretion. This work opens up new avenues for allosteric drug discovery by directly targeting modulation of metabolites, but it also identifies a behavior that could contribute to unexpected clinical outcomes if interaction of allosteric drugs with metabolites is not part of their preclinical assessment.

The Influence of Computer-Mediated Communication Systems on Community

Science.gov (United States)

Rockinson-Szapkiw, Amanda J.

2012-01-01

As higher education institutions enter the intense competition of the rapidly growing global marketplace of online education, the leaders within these institutions are challenged to identify factors critical for developing and for maintaining effective online courses. Computer-mediated communication (CMC) systems are considered critical to…

Anticipated Ongoing Interaction versus Channel Effects of Relational Communication in Computer-Mediated Interaction.

Science.gov (United States)

Walther, Joseph B.

1994-01-01

Assesses the related effects of anticipated future interaction and different communication media (computer-mediated versus face-to-face communication) on the communication of relational intimacy and composure. Shows that the assignment of long-term versus short-term partnerships has a larger impact on anticipated future interaction reported by…

Mediatization and Government Communication

DEFF Research Database (Denmark)

Laursen, Bo; Valentini, Chiara

2015-01-01

do not tend to get a media coverage that matches the EU’s considerable influence on European citizens’ daily lives. This study, which is based on in-depth interviews with European Parliament press officers, concludes that these professionals are indeed attuned to a “media logic......Social actors see exposure in the news media as attractive for publicity purposes and are under pressure to adapt their press work to a “media logic” to be attractive sources for journalists and editors. This article investigates the European Parliament’s press officers’ professional practices...... in the light of mediatization and government communication theories. Without one pan-European public sphere, the European Parliament, like the other European Union (EU) institutions, competes with national actors for the news media’s attention in the EU’s twenty-eight national public spheres, where EU affairs...

Use of allosteric targets in the discovery of safer drugs.

Science.gov (United States)

Grover, Ashok Kumar

2013-01-01

The need for drugs with fewer side effects cannot be overemphasized. Today, most drugs modify the actions of enzymes, receptors, transporters and other molecules by directly binding to their active (orthosteric) sites. However, orthosteric site configuration is similar in several proteins performing related functions and this leads to a lower specificity of a drug for the desired protein. Consequently, such drugs may have adverse side effects. A new basis of drug discovery is emerging based on the binding of the drug molecules to sites away (allosteric) from the orthosteric sites. It is possible to find allosteric sites which are unique and hence more specific as targets for drug discovery. Of many available examples, two are highlighted here. The first is caloxins - a new class of highly specific inhibitors of plasma membrane Ca²⁺ pumps. The second concerns the modulation of receptors for the neurotransmitter acetylcholine, which binds to 12 types of receptors. Exploitation of allosteric sites has led to the discovery of drugs which can selectively modulate the activation of only 1 (M1 muscarinic) out of the 12 different types of acetylcholine receptors. These drugs are being tested for schizophrenia treatment. It is anticipated that the drug discovery exploiting allosteric sites will lead to more effective therapeutic agents with fewer side effects. Copyright © 2013 S. Karger AG, Basel.

An Exploratory Analysis of Computer Mediated Communications on Cyberstalking Severity

Directory of Open Access Journals (Sweden)

Stephen D. Barnes

2007-09-01

Full Text Available The interaction between disjunctive interpersonal relationships, those where the parties to the relationship disagree on the goals of the relationship, and the use of computer mediated communications channels is a relatively unexplored domain.  Bargh (2002 suggests that CMC channels can amplify the development of interpersonal relationships, and notes that the effect is not constant across communications activities.  This proposal suggests a line of research that explores the interaction between computer mediated communications (CMC and stalking, which is a common form of disjunctive relationships.  Field data from cyberstalking cases will be used to look at the effects of CMC channels on stalking case severity, and exploring the relative impacts of CMC channel characteristics on such cases.  To accomplish this, a ratio scaled measure of stalking case severity is proposed for use in exploring the relationship between case severity and CMC media characteristics, anonymity, and the prior relationship between the stalker and the victim.  Expected results are identified, and follow-up research is proposed. 

Non-site-specific allosteric effect of oxygen on human hemoglobin under high oxygen partial pressure.

Science.gov (United States)

Takayanagi, Masayoshi; Kurisaki, Ikuo; Nagaoka, Masataka

2014-04-08

Protein allostery is essential for vital activities. Allosteric regulation of human hemoglobin (HbA) with two quaternary states T and R has been a paradigm of allosteric structural regulation of proteins. It is widely accepted that oxygen molecules (O2) act as a "site-specific" homotropic effector, or the successive O2 binding to the heme brings about the quaternary regulation. However, here we show that the site-specific allosteric effect is not necessarily only a unique mechanism of O2 allostery. Our simulation results revealed that the solution environment of high O2 partial pressure enhances the quaternary change from T to R without binding to the heme, suggesting an additional "non-site-specific" allosteric effect of O2. The latter effect should play a complementary role in the quaternary change by affecting the intersubunit contacts. This analysis must become a milestone in comprehensive understanding of the allosteric regulation of HbA from the molecular point of view.

Nootropic α7 nicotinic receptor allosteric modulator derived from GABAA receptor modulators

Science.gov (United States)

Ng, Herman J.; Whittemore, Edward R.; Tran, Minhtam B.; Hogenkamp, Derk J.; Broide, Ron S.; Johnstone, Timothy B.; Zheng, Lijun; Stevens, Karen E.; Gee, Kelvin W.

2007-01-01

Activation of brain α7 nicotinic acetylcholine receptors (α7 nAChRs) has broad therapeutic potential in CNS diseases related to cognitive dysfunction, including Alzheimer's disease and schizophrenia. In contrast to direct agonist activation, positive allosteric modulation of α7 nAChRs would deliver the clinically validated benefits of allosterism to these indications. We have generated a selective α7 nAChR-positive allosteric modulator (PAM) from a library of GABAA receptor PAMs. Compound 6 (N-(4-chlorophenyl)-α-[[(4-chloro-phenyl)amino]methylene]-3-methyl-5-isoxazoleacet-amide) evokes robust positive modulation of agonist-induced currents at α7 nAChRs, while preserving the rapid native characteristics of desensitization, and has little to no efficacy at other ligand-gated ion channels. In rodent models, it corrects sensory-gating deficits and improves working memory, effects consistent with cognitive enhancement. Compound 6 represents a chemotype for allosteric activation of α7 nAChRs, with therapeutic potential in CNS diseases with cognitive dysfunction. PMID:17470817

A unified view of "how allostery works".

Science.gov (United States)

Tsai, Chung-Jung; Nussinov, Ruth

2014-02-01

The question of how allostery works was posed almost 50 years ago. Since then it has been the focus of much effort. This is for two reasons: first, the intellectual curiosity of basic science and the desire to understand fundamental phenomena, and second, its vast practical importance. Allostery is at play in all processes in the living cell, and increasingly in drug discovery. Many models have been successfully formulated, and are able to describe allostery even in the absence of a detailed structural mechanism. However, conceptual schemes designed to qualitatively explain allosteric mechanisms usually lack a quantitative mathematical model, and are unable to link its thermodynamic and structural foundations. This hampers insight into oncogenic mutations in cancer progression and biased agonists' actions. Here, we describe how allostery works from three different standpoints: thermodynamics, free energy landscape of population shift, and structure; all with exactly the same allosteric descriptors. This results in a unified view which not only clarifies the elusive allosteric mechanism but also provides structural grasp of agonist-mediated signaling pathways, and guides allosteric drug discovery. Of note, the unified view reasons that allosteric coupling (or communication) does not determine the allosteric efficacy; however, a communication channel is what makes potential binding sites allosteric.

Neurotransmitter-Triggered Transfer of Exosomes Mediates Oligodendrocyte–Neuron Communication

Science.gov (United States)

Kuo, Wen Ping; Amphornrat, Jesa; Thilemann, Sebastian; Saab, Aiman S.; Kirchhoff, Frank; Möbius, Wiebke; Goebbels, Sandra; Nave, Klaus-Armin; Schneider, Anja; Simons, Mikael; Klugmann, Matthias; Trotter, Jacqueline; Krämer-Albers, Eva-Maria

2013-01-01

Reciprocal interactions between neurons and oligodendrocytes are not only crucial for myelination, but also for long-term survival of axons. Degeneration of axons occurs in several human myelin diseases, however the molecular mechanisms of axon-glia communication maintaining axon integrity are poorly understood. Here, we describe the signal-mediated transfer of exosomes from oligodendrocytes to neurons. These endosome-derived vesicles are secreted by oligodendrocytes and carry specific protein and RNA cargo. We show that activity-dependent release of the neurotransmitter glutamate triggers oligodendroglial exosome secretion mediated by Ca2+ entry through oligodendroglial NMDA and AMPA receptors. In turn, neurons internalize the released exosomes by endocytosis. Injection of oligodendroglia-derived exosomes into the mouse brain results in functional retrieval of exosome cargo in neurons. Supply of cultured neurons with oligodendroglial exosomes improves neuronal viability under conditions of cell stress. These findings indicate that oligodendroglial exosomes participate in a novel mode of bidirectional neuron-glia communication contributing to neuronal integrity. PMID:23874151

Neurotransmitter-triggered transfer of exosomes mediates oligodendrocyte-neuron communication.

Science.gov (United States)

Frühbeis, Carsten; Fröhlich, Dominik; Kuo, Wen Ping; Amphornrat, Jesa; Thilemann, Sebastian; Saab, Aiman S; Kirchhoff, Frank; Möbius, Wiebke; Goebbels, Sandra; Nave, Klaus-Armin; Schneider, Anja; Simons, Mikael; Klugmann, Matthias; Trotter, Jacqueline; Krämer-Albers, Eva-Maria

2013-07-01

Reciprocal interactions between neurons and oligodendrocytes are not only crucial for myelination, but also for long-term survival of axons. Degeneration of axons occurs in several human myelin diseases, however the molecular mechanisms of axon-glia communication maintaining axon integrity are poorly understood. Here, we describe the signal-mediated transfer of exosomes from oligodendrocytes to neurons. These endosome-derived vesicles are secreted by oligodendrocytes and carry specific protein and RNA cargo. We show that activity-dependent release of the neurotransmitter glutamate triggers oligodendroglial exosome secretion mediated by Ca²⁺ entry through oligodendroglial NMDA and AMPA receptors. In turn, neurons internalize the released exosomes by endocytosis. Injection of oligodendroglia-derived exosomes into the mouse brain results in functional retrieval of exosome cargo in neurons. Supply of cultured neurons with oligodendroglial exosomes improves neuronal viability under conditions of cell stress. These findings indicate that oligodendroglial exosomes participate in a novel mode of bidirectional neuron-glia communication contributing to neuronal integrity.

The identity of functional diversity in communication mediated by technology

Directory of Open Access Journals (Sweden)

Carmen Montalba-Ocaña

2017-12-01

Full Text Available The subject matter of the research presented below gravitates on the ontological change imposed by technology in humans. In particular, development of assistive technologies applied to alternative communication systems represents an interesting example of how this technology works on the social relationships, communication, and how this mediation modifies the self-image and social image of the users. This study focuses on people with cerebral palsy or neuronal degenerative disease and the identity transformation suffering to be able to communicate with autonomous tech support. In this way, the hypotheses to be faced in this study are: technology (paradoxically humanizes.

Video-mediated communication to support distant family connectedness.

Science.gov (United States)

Furukawa, Ryoko; Driessnack, Martha

2013-02-01

It can be difficult to maintain family connections with geographically distant members. However, advances in computer-human interaction (CHI) systems, including video-mediated communication (VMC) are emerging. While VMC does not completely substitute for physical face-to-face communication, it appears to provide a sense of virtual copresence through the addition of visual and contextual cues to verbal communication between family members. The purpose of this study was to explore current patterns of VMC use, experiences, and family functioning among self-identified VMC users separated geographically from their families. A total of 341 participants (ages 18 to above 70) completed an online survey and Family APGAR. Ninty-six percent of the participants reported that VMC was the most common communication method used and 60% used VMC at least once/week. The most common reason cited for using VMC over other methods of communication was the addition of visual cues. A significant difference between the Family APGAR scores and the number of positive comments about VMC experience was also found. This exploratory study provides insight into the acceptance of VMC and its usefulness in maintaining connections with distant family members.

Two Studies Examining Argumentation in Asynchronous Computer Mediated Communication

Science.gov (United States)

Joiner, Richard; Jones, Sarah; Doherty, John

2008-01-01

Asynchronous computer mediated communication (CMC) would seem to be an ideal medium for supporting development in student argumentation. This paper investigates this assumption through two studies. The first study compared asynchronous CMC with face-to-face discussions. The transactional and strategic level of the argumentation (i.e. measures of…

Lay Theories Regarding Computer-Mediated Communication in Remote Collaboration

Science.gov (United States)

Parke, Karl; Marsden, Nicola; Connolly, Cornelia

2017-01-01

Computer-mediated communication and remote collaboration has become an unexceptional norm as an educational modality for distance and open education, therefore the need to research and analyze students' online learning experience is necessary. This paper seeks to examine the assumptions and expectations held by students in regard to…

Characterisation of endogenous A2A and A2B receptor-mediated cyclic AMP responses in HEK 293 cells using the GloSensor™ biosensor: Evidence for an allosteric mechanism of action for the A2B-selective antagonist PSB 603.

Science.gov (United States)

Goulding, Joelle; May, Lauren T; Hill, Stephen J

2018-01-01

Endogenous adenosine A 2B receptors (A 2B AR) mediate cAMP accumulation in HEK 293 cells. Here we have used a biosensor to investigate the mechanism of action of the A 2B AR antagonist PSB 603 in HEK 293 cells. The A 2A agonist CGS 21680 elicited a small response in these cells (circa 20% of that obtained with NECA), suggesting that they also contain a small population of A 2A receptors. The responses to NECA and adenosine were antagonised by PSB 603, but not by the selective A 2A AR antagonist SCH 58261. In contrast, CGS 21680 responses were not antagonised by high concentrations of PSB 603, but were sensitive to inhibition by SCH 58261. Analysis of the effect of increasing concentrations of PSB 603 on the response to NECA indicated a non-competitive mode of action yielding a marked reduction in the NECA E MAX with no significant effect on EC 50 values. Kinetics analysis of the effect of PSB 603 on the A 2B AR-mediated NECA responses confirmed a saturable effect that was consistent with an allosteric mode of antagonism. The possibility that PSB 603 acts as a negative allosteric modulator of A 2B AR suggests new approaches to the development of therapeutic agents to treat conditions where adenosine levels are high. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Using Bourdieu in Critical Mediatization Research: Communicational Doxa and Osmotic Pressures in the Field of UN Organizations

Directory of Open Access Journals (Sweden)

André Jansson

2015-05-01

Full Text Available This article develops a Bourdieusian approach to mediatization. It is argued that the Bourdieusian theories of doxa and fields can make valuable contributions to a critical perspective on mediatization, one that moves beyond the divides between institutionalist, social-constructivist and materialist understandings (e.g., Bourdieu, 1972/1977. Mediatization is here seen as the historically growing dependence on media technologies and institutions within diverse social fields and settings. In order to establish the link between mediatization and Bourdieu’s theories (ibid., the article introduces the concept of communicational doxa, which refers to the taken for granted communicational conventions and demands that regulate the inclusion of membership within a particular field. The article also shows how communicational doxa can be applied as an analytical concept. Findings from qualitative fieldwork carried out among highly mobile and skilled professionals within the field of UN organizations in Geneva, show how the autonomy of social agents is negotiated in relation to an increasingly mediatized communicational doxa.

Allosteric regulation of rhomboid intramembrane proteolysis.

Science.gov (United States)

Arutyunova, Elena; Panwar, Pankaj; Skiba, Pauline M; Gale, Nicola; Mak, Michelle W; Lemieux, M Joanne

2014-09-01

Proteolysis within the lipid bilayer is poorly understood, in particular the regulation of substrate cleavage. Rhomboids are a family of ubiquitous intramembrane serine proteases that harbour a buried active site and are known to cleave transmembrane substrates with broad specificity. In vitro gel and Förster resonance energy transfer (FRET)-based kinetic assays were developed to analyse cleavage of the transmembrane substrate psTatA (TatA from Providencia stuartii). We demonstrate significant differences in catalytic efficiency (kcat/K0.5) values for transmembrane substrate psTatA (TatA from Providencia stuartii) cleavage for three rhomboids: AarA from P. stuartii, ecGlpG from Escherichia coli and hiGlpG from Haemophilus influenzae demonstrating that rhomboids specifically recognize this substrate. Furthermore, binding of psTatA occurs with positive cooperativity. Competitive binding studies reveal an exosite-mediated mode of substrate binding, indicating allostery plays a role in substrate catalysis. We reveal that exosite formation is dependent on the oligomeric state of rhomboids, and when dimers are dissociated, allosteric substrate activation is not observed. We present a novel mechanism for specific substrate cleavage involving several dynamic processes including positive cooperativity and homotropic allostery for this interesting class of intramembrane proteases. © 2014 The Authors.

The New Orality: Oral Characteristics of Computer-Mediated Communication.

Science.gov (United States)

Ferris, Sharmila Pixy; Montgomery, Maureen

1996-01-01

Considers the characteristics of orality and literacy developed in the work of scholars such as Walter Ong to consider computer-mediated communication (CMC) as the potential site of a "new orality" which is neither purely oral or literate. Notes that the medium of CMC is writing, which has traditionally represented the…

Effect Size Measures for Mediation Models: Quantitative Strategies for Communicating Indirect Effects

Science.gov (United States)

Preacher, Kristopher J.; Kelley, Ken

2011-01-01

The statistical analysis of mediation effects has become an indispensable tool for helping scientists investigate processes thought to be causal. Yet, in spite of many recent advances in the estimation and testing of mediation effects, little attention has been given to methods for communicating effect size and the practical importance of those…

Defining Business Communication Using the Movie "The Insider" as Mediator of Students' Thought Processes.

Science.gov (United States)

Rodriguez-Talavera, Leticia

Business communication is different from other domains in that its contextual meaning requires previous metacognitive mediation of signs. The communicative process in business is aimed at accomplishing a specific outcome. Various forms of meaning come into play in business communication such as denotative, connotative, stylistic, affective,…

Testing a Mediational Model of Communication Among Medical Staff and Families of Cancer Patients

Science.gov (United States)

Gionta, Dana A.; Harlow, Lisa L.; Loitman, Jane E.; Leeman, Joanne M.

2005-01-01

Three structural equation models of communication between family members and medical staff were examined to understand relations among staff accessibility, inhibitory family attitudes, getting communication needs met, perceived stress, and satisfaction with communication. Compared to full and direct models, a mediational model fit best in which…

2013 Philip S. Portoghese Medicinal Chemistry Lectureship: Drug Discovery Targeting Allosteric Sites†

Science.gov (United States)

2015-01-01

The identification of sites on receptors topographically distinct from the orthosteric sites, so-called allosteric sites, has heralded novel approaches and modes of pharmacology for target modulation. Over the past 20 years, our understanding of allosteric modulation has grown significantly, and numerous advantages, as well as caveats (e.g., flat structure–activity relationships, species differences, “molecular switches”), have been identified. For multiple receptors and proteins, numerous examples have been described where unprecedented levels of selectivity are achieved along with improved physiochemical properties. While not a panacea, these novel approaches represent exciting opportunities for tool compound development to probe the pharmacology and therapeutic potential of discrete molecular targets, as well as new medicines. In this Perspective, in commemoration of the 2013 Philip S. Portoghese Medicinal Chemistry Lectureship (LindsleyC. W.Adventures in allosteric drug discovery. Presented at the 246th National Meeting of the American Chemical Society, Indianapolis, IN, September 10, 2013; The 2013 Portoghese Lectureship), several vignettes of drug discovery campaigns targeting novel allosteric mechanisms will be recounted, along with lessons learned and guidelines that have emerged for successful lead optimization. PMID:25180768

Getting Real: A Naturalistic Methodology for Using Smartphones to Collect Mediated Communications

Directory of Open Access Journals (Sweden)

Chad C. Tossell

2012-01-01

Full Text Available This paper contributes an intentionally naturalistic methodology using smartphone logging technology to study communications in the wild. Smartphone logging can provide tremendous access to communications data from real environments. However, researchers must consider how it is employed to preserve naturalistic behaviors. Nine considerations are presented to this end. We also provide a description of a naturalistic logging approach that has been applied successfully to collecting mediated communications from iPhones. The methodology was designed to intentionally decrease reactivity and resulted in data that were more accurate than self-reports. Example analyses are also provided to show how data collected can be analyzed to establish empirical patterns and identify user differences. Smartphone logging technologies offer flexible capabilities to enhance access to real communications data, but methodologies employing these techniques must be designed appropriately to avoid provoking naturally occurring behaviors. Functionally, this methodology can be applied to establish empirical patterns and test specific hypotheses within the field of HCI research. Topically, this methodology can be applied to domains interested in understanding mediated communications such as mobile content and systems design, teamwork, and social networks.

Learning Opportunities in Synchronous Computer-Mediated Communication and Face-to-Face Interaction

Science.gov (United States)

Kim, Hye Yeong

2014-01-01

This study investigated how synchronous computer-mediated communication (SCMC) and face-to-face (F2F) oral interaction influence the way in which learners collaborate in language learning and how they solve their communicative problems. The findings suggest that output modality may affect how learners produce language, attend to linguistic forms,…

Does early communication mediate the relationship between motor ability and social function in children with cerebral palsy?

Science.gov (United States)

Lipscombe, Belinda; Boyd, Roslyn N; Coleman, Andrea; Fahey, Michael; Rawicki, Barry; Whittingham, Koa

2016-01-01

Children diagnosed with neurodevelopmental conditions such as cerebral palsy (CP) are at risk of experiencing restrictions in social activities negatively impacting their subsequent social functioning. Research has identified motor and communication ability as being unique determinants of social function capabilities in children with CP, to date, no research has investigated whether communication is a mediator of the relationship between motor ability and social functioning. To investigate whether early communication ability at 24 months corrected age (ca.) mediates the relationship between early motor ability at 24 months ca. and later social development at 60 months ca. in a cohort of children diagnosed with cerebral palsy (CP). A cohort of 71 children (43 male) diagnosed with CP (GMFCS I=24, 33.8%, II=9, 12.7%, III=12, 16.9%, IV=10, 14.1%, V=16, 22.5%) were assessed at 24 and 60 months ca. Assessments included the Gross Motor Function Measure (GMFM), the Communication and Symbolic Behaviour Scales-Developmental Profile (CSBS-DP) Infant-Toddler Checklist and the Paediatric Evaluation of Disability Inventory (PEDI). A mediation model was examined using bootstrapping. Early communication skills mediated the relationship between early motor abilities and later social functioning, b=0.24 (95% CI=0.08-0.43 and the mediation model was significant, F (2, 68)=32.77, pcommunication ability partially mediates the relationship between early motor ability and later social function in children with CP. This demonstrates the important role of early communication in ongoing social development. Early identification of communication delay and enriched language exposure is crucial in this population. Copyright © 2016 Elsevier Ltd. All rights reserved.

An expanded allosteric network in PTP1B by multitemperature crystallography, fragment screening, and covalent tethering.

Science.gov (United States)

Keedy, Daniel A; Hill, Zachary B; Biel, Justin T; Kang, Emily; Rettenmaier, T Justin; Brandao-Neto, Jose; Pearce, Nicholas M; von Delft, Frank; Wells, James A; Fraser, James S

2018-06-07

Allostery is an inherent feature of proteins, but it remains challenging to reveal the mechanisms by which allosteric signals propagate. A clearer understanding of this intrinsic circuitry would afford new opportunities to modulate protein function. Here we have identified allosteric sites in protein tyrosine phosphatase 1B (PTP1B) by combining multiple-temperature X-ray crystallography experiments and structure determination from hundreds of individual small-molecule fragment soaks. New modeling approaches reveal 'hidden' low-occupancy conformational states for protein and ligands. Our results converge on allosteric sites that are conformationally coupled to the active-site WPD loop and are hotspots for fragment binding. Targeting one of these sites with covalently tethered molecules or mutations allosterically inhibits enzyme activity. Overall, this work demonstrates how the ensemble nature of macromolecular structure, revealed here by multitemperature crystallography, can elucidate allosteric mechanisms and open new doors for long-range control of protein function. © 2018, Keedy et al.

Computer-mediated communication: from a cognitive to a discursive model

NARCIS (Netherlands)

Lamerichs, J.M.W.J.; Molder, te H.F.M.

2003-01-01

In this article, we evaluate the ways in which computer-mediated communication (CMC) has thus far been conceptualized, proposing an alternative approach. It is argued that traditional perspectives ignore participants' everyday understanding of media use and media characteristics by relying on an

Computer-mediated communication: from a cognitive to a discursive model

NARCIS (Netherlands)

Lamerichs, J.M.W.J.; Te Molder, Hedwig

2003-01-01

In this article, we evaluate the ways in which computer-mediated communication (CMC) has thus far been conceptualized, proposing an alternative approach. It is argued that traditional perspectives ignore participants’ everyday understanding of media use and media characteristics by relying on an

Allosteric and orthosteric sites in CC chemokine receptor (CCR5), a chimeric receptor approach

DEFF Research Database (Denmark)

Thiele, Stefanie; Steen, Anne; Jensen, Pia C

2011-01-01

-allosteric molecules. A chimera was successfully constructed between CCR5 and the closely related CCR2 by transferring all extracellular regions of CCR2 to CCR5, i.e. a Trojan horse that resembles CCR2 extracellularly but signals through a CCR5 transmembrane unit. The chimera bound CCR2 (CCL2 and CCL7), but not CCR5...... preserved, the allosteric enhancement of chemokine binding was disrupted. In summary, the Trojan horse chimera revealed that orthosteric and allosteric sites could be structurally separated and still act together with transmission of agonism and antagonism across the different receptor units....

A generalized allosteric mechanism for cis-regulated cyclic nucleotide binding domains.

Directory of Open Access Journals (Sweden)

Alexandr P Kornev

2008-04-01

Full Text Available Cyclic nucleotides (cAMP and cGMP regulate multiple intracellular processes and are thus of a great general interest for molecular and structural biologists. To study the allosteric mechanism of different cyclic nucleotide binding (CNB domains, we compared cAMP-bound and cAMP-free structures (PKA, Epac, and two ionic channels using a new bioinformatics method: local spatial pattern alignment. Our analysis highlights four major conserved structural motifs: 1 the phosphate binding cassette (PBC, which binds the cAMP ribose-phosphate, 2 the "hinge," a flexible helix, which contacts the PBC, 3 the beta(2,3 loop, which provides precise positioning of an invariant arginine from the PBC, and 4 a conserved structural element consisting of an N-terminal helix, an eight residue loop and the A-helix (N3A-motif. The PBC and the hinge were included in the previously reported allosteric model, whereas the definition of the beta(2,3 loop and the N3A-motif as conserved elements is novel. The N3A-motif is found in all cis-regulated CNB domains, and we present a model for an allosteric mechanism in these domains. Catabolite gene activator protein (CAP represents a trans-regulated CNB domain family: it does not contain the N3A-motif, and its long range allosteric interactions are substantially different from the cis-regulated CNB domains.

Emoticons in computer-mediated communication: social motives and social context.

Science.gov (United States)

Derks, Daantje; Bos, Arjan E R; von Grumbkow, Jasper

2008-02-01

This study investigated the role of emoticons in computer-mediated communication (CMC). The study consisted of an online questionnaire about the social motives for emoticon use and an experimental part in which participants (N = 1,251) had to respond to short Internet chats. In these chats, the interaction partner (friend vs. stranger) and the valence of the context (positive vs. negative) were manipulated. Results showed that emoticons are mostly used to express emotion, to strengthen a message, and to express humor. Furthermore, more emoticons were used in communication with friends than in communication with strangers, and more emoticons were used in a positive context than in a negative context. Participants seem to use emoticons in a way similar to facial behavior in face-to-face communication with respect to social context and interaction partner.

Exosome-Mediated Genetic Information Transfer, a Missing Piece of Osteoblast-Osteoclast Communication Puzzle.

Science.gov (United States)

Yin, Pengbin; Lv, Houchen; Li, Yi; Deng, Yuan; Zhang, Licheng; Tang, Peifu

2017-01-01

The skeletal system functions and maintains itself based on communication between cells of diverse origins, especially between osteoblasts (OBs) and osteoclasts (OCs), accounting for bone formation and resorption, respectively. Previously, protein-level information exchange has been the research focus, and this has been discussed in detail. The regulative effects of microRNAs (miRNAs) on OB and OC ignite the question as to whether genetic information could be transferred between bone cells. Exosomes, extracellular membrane vesicles 30-100 nm in diameter, have recently been demonstrated to transfer functional proteins, mRNAs, and miRNAs, and serve as mediators of intercellular communication. By reviewing the distinguishing features of exosomes, a hypothesis was formulated and evaluated in this article that exosome-mediated genetic information transfer may represent a novel strategy for OB-OC communication. The exosomes may coordinately regulate these two cells under certain physiological conditions by transferring genetic information. Further research in exosome-shuttered miRNAs in OB-OC communication may add a missing piece to the bone cells communication "puzzle."

Tuning Transcriptional Regulation through Signaling: A Predictive Theory of Allosteric Induction.

Science.gov (United States)

Razo-Mejia, Manuel; Barnes, Stephanie L; Belliveau, Nathan M; Chure, Griffin; Einav, Tal; Lewis, Mitchell; Phillips, Rob

2018-04-25

Allosteric regulation is found across all domains of life, yet we still lack simple, predictive theories that directly link the experimentally tunable parameters of a system to its input-output response. To that end, we present a general theory of allosteric transcriptional regulation using the Monod-Wyman-Changeux model. We rigorously test this model using the ubiquitous simple repression motif in bacteria by first predicting the behavior of strains that span a large range of repressor copy numbers and DNA binding strengths and then constructing and measuring their response. Our model not only accurately captures the induction profiles of these strains, but also enables us to derive analytic expressions for key properties such as the dynamic range and [EC 50 ]. Finally, we derive an expression for the free energy of allosteric repressors that enables us to collapse our experimental data onto a single master curve that captures the diverse phenomenology of the induction profiles. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

A dynamically coupled allosteric network underlies binding cooperativity in Src kinase.

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Foda, Zachariah H; Shan, Yibing; Kim, Eric T; Shaw, David E; Seeliger, Markus A

2015-01-20

Protein tyrosine kinases are attractive drug targets because many human diseases are associated with the deregulation of kinase activity. However, how the catalytic kinase domain integrates different signals and switches from an active to an inactive conformation remains incompletely understood. Here we identify an allosteric network of dynamically coupled amino acids in Src kinase that connects regulatory sites to the ATP- and substrate-binding sites. Surprisingly, reactants (ATP and peptide substrates) bind with negative cooperativity to Src kinase while products (ADP and phosphopeptide) bind with positive cooperativity. We confirm the molecular details of the signal relay through the allosteric network by biochemical studies. Experiments on two additional protein tyrosine kinases indicate that the allosteric network may be largely conserved among these enzymes. Our work provides new insights into the regulation of protein tyrosine kinases and establishes a potential conduit by which resistance mutations to ATP-competitive kinase inhibitors can affect their activity.

Ethnic inequalities in doctor-patient communication regarding personal care plans: the mediating effects of positive mental wellbeing.

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Umeh, Kanayo F

2017-04-06

There is limited understanding of ethnic inequalities in doctor-patient communication regarding personal care plans (PCPs). This study investigated the mediating effects of positive mental wellbeing on differences in PCP-related doctor-patient communication amongst South Asian and Caucasian UK residents. Data from 10,980 respondents to the 2013 Health Survey for England was analysed using bootstrapping methods. Constructs from the WEMWBS (Warwick and Edinburgh Mental Wellbeing Scale) (Stewart-Brown, S., and K. Janmohamed. 2008. Warwick, UK) were assessed as mediators of relations between ethnicity and several doctor-patient communication variables, including PCP-related interactions; (a) had a PCP-related discussion about a long-term condition with a doctor/nurse, and (b) had this conversation within the past year, (c) agreed to a PCP with a health professional; and (d) talked to a doctor in the past 2 weeks. Bootstrapped mediation analysis (Hayes, A. F. 2013. Introduction to Mediation, Moderation, and Conditional Process Analysis: A Regression-based Approach. New York, NY: The Guilford Press) showed that three positive mind-sets mediated associations between ethnicity and doctor-patient contact, including PCP-related communication. Being able to make up one's mind (ab = -0.05; BC a CI [-0.14, 0.01]) mediated the effect of ethnicity on agreeing to a PCP, while having energy to spare (ab = 0.07; BC a CI [-0.04, 0.12]), and feeling good about oneself (ab = 0.03; BC a CI [0.01, 0.07]), mediated ethnic effects on talking to a doctor during the past fortnight. The mediating effect of reported energy persisted after controlling for medical history, perceived health, and other covariates. Ethnic disparities in doctor-patient interaction, including PCP-related communication, are partly explained by positive mental wellbeing. Gauging positive psychological moods in patients, particularly self-worth, self-perceived vigour and decisiveness, are relevant to

Mediation Training for the Physician: Expanding the Communication Toolkit to Manage Conflict.

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Kayser, Joshua B

2015-01-01

Good communication is critical to the practice of medicine. This is particularly true when outcomes are unpredictable and/or patients lack the capacity to participate in medical decision making. Disputes may develop that cannot be addressed using basic communication skills. Conflict of this nature can burden patients, families, and medical staff and may result in increased suffering for all parties. Many physicians lack the necessary communication tools to handle difficult conversations. Training in bioethics mediation provides physicians with skills that can promote healing by empowering participants to engage in effective discourse and break down barriers to find common ground. Mediation training for physicians can expand their capacity to connect with patients and enhance their ability to identify potential conflict early on, in order to collaborate more effectively. Competency in the processes of negotiation and conflict resolution should therefore be seen as essential elements of medical training. Copyright 2015 The Journal of Clinical Ethics. All rights reserved.

COMMUNICATIVE ASPECTS OF MULTILINGUAL CODE SWITCHING IN COMPUTER-MEDIATED COMMUNICATION

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Pilar Caparas

2017-09-01

Full Text Available The quintessential role of language has been punctiliously studied relative to intercultural communication, cultural heritage, social development, education, identity construction and many more domains. One forum wherein language is investigated is the Computer-mediated Communication (CMC which provides a fertile ground for linguistic and sociolinguistic analyses. The present study aims at investigating the preferred codes used in code switching (CS, functions of CS, and the motives of users for employing CS in CMC. The present study was based on the investigation of 200 status updates and 100 wall posts of 50 Facebook accounts of students who are enrolled in a leading state university in Mindanao and professionals who graduated from the same university. Besides English and Filipino, these Facebook users speak various regional languages such as Chavacano, Cebuano, and Tausug. Their posts were analyzed employing eclectic approaches in analyzing inter-sentential and intra-sentential code switching. The findings reveal that the preferred code in their online communication is Taglish. It implies that Taglish is an equalizer, non-privileging, non-discriminating, and more unifying. The primary reason for CS is because of real lexical need. Besides the given categories, the study determined four other reasons for CS, namely: to express ideas spontaneously, to retain native terminology, to express disappointment, and to promote relationship. The findings vouch for the viability of regional languages to co-exist with English and other languages in the gamut of human interactions in the internet.

COMPUTER-MEDIATED COMMUNICATION IN FOREIGN LANGUAGE EDUCATION: Use of Target Language and Learner Perceptions

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Nesrin OZDENER

2008-04-01

Full Text Available Among the challenges many teachers face in facilitating the improvement of speaking skills are sparing sufficient time for practice to enable students to achieve fluency in speaking through internalizing the structures, and establishing a balance between fluency and accuracy. This study aimed to seek an answer to the question as to whether Computer-Mediated Communication Technologies be a solution for overcoming these problems. The study was conducted as additional practice to the foreign language lessons with the participation of 60 students. Task-based language teaching principles were taken as basis in preparation of the teaching materials in the study, in which text and voice chat applications among the Computer-Mediated Communication Technologies were used. During the applications data were collected in several ways: participants’ perspectives regarding their changing experiences and the types of tasks used were investigated through the use of open-ended questionnaires after each session; a general insight was obtained into the students’ experiences with close-ended questionnaires given at the end of the study; and the use of the target language in communications among students were determined by investigating the text communication logs. From a user-oriented perspective, the results of the study shed light on the strategies that can be used in computer-mediated communication technologies valuing the experiences and perceptions of the learners.

Are AMPA Receptor Positive Allosteric Modulators Potential Pharmacotherapeutics for Addiction?

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Lucas R. Watterson

2013-12-01

Full Text Available Positive allosteric modulators (PAMs of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA receptors are a diverse class of compounds that increase fast excitatory transmission in the brain. AMPA PAMs have been shown to facilitate long-term potentiation, strengthen communication between various cortical and subcortical regions, and some of these compounds increase the production and release of brain-derived neurotrophic factor (BDNF in an activity-dependent manner. Through these mechanisms, AMPA PAMs have shown promise as broad spectrum pharmacotherapeutics in preclinical and clinical studies for various neurodegenerative and psychiatric disorders. In recent years, a small collection of preclinical animal studies has also shown that AMPA PAMs may have potential as pharmacotherapeutic adjuncts to extinction-based or cue-exposure therapies for the treatment of drug addiction. The present paper will review this preclinical literature, discuss novel data collected in our laboratory, and recommend future research directions for the possible development of AMPA PAMs as anti-addiction medications.

Student Participation and Interactivity Using Asynchronous Computer-Mediated Communication for Resolution of an Undergraduate Capstone Management Case Study

OpenAIRE

Miller, Paulette J.

2012-01-01

Online discussion activities are designed for computer-mediated learning activities in face-to-face, hybrid, and totally online courses. The use of asynchronous computer-mediated communication (A-CMC) coupled with authentic workplace case studies provides students in the protected learning environment with opportunities to practice workplace decision making and communication. In this study, communication behaviors of transmitter and receiver were analyzed to determine participation and intera...

Student participation and interactivity using asynchronous computer-mediated communication for resolution of an undergraduate capstone management case study.

Science.gov (United States)

Miller, Paulette J

2012-01-01

Online discussion activities are designed for computer-mediated learning activities in face-to-face, hybrid, and totally online courses. The use of asynchronous computer-mediated communication (A-CMC) coupled with authentic workplace case studies provides students in the protected learning environment with opportunities to practice workplace decision making and communication. In this study, communication behaviors of transmitter and receiver were analyzed to determine participation and interactivity in communication among small-group participants in a health information management capstone management course.

[Mediate evaluation of replicating a Training Program in Nonverbal Communication in Gerontology].

Science.gov (United States)

Schimidt, Teresa Cristina Gioia; Duarte, Yeda Aparecida de Oliveira; Silva, Maria Julia Paes da

2015-04-01

Replicating the training program in non-verbal communication based on the theoretical framework of interpersonal communication; non-verbal coding, valuing the aging aspects in the perspective of active aging, checking its current relevance through the content assimilation index after 90 days (mediate) of its application. A descriptive and exploratory field study was conducted in three hospitals under direct administration of the state of São Paulo that caters exclusively to Unified Health System (SUS) patients. The training lasted 12 hours divided in three meetings, applied to 102 health professionals. Revealed very satisfactory and satisfactory mediate content assimilation index in 82.9%. The program replication proved to be relevant and updated the setting of hospital services, while remaining efficient for healthcare professionals.

Effects of the Educational Leadership of Nursing Unit Managers on Team Effectiveness: Mediating Effects of Organizational Communication.

Science.gov (United States)

Choi, Eun Ha; Kim, Eun-Kyung; Kim, Pil Bong

2018-03-31

EDUCATIONAL LEADERSHIP OF NURSING UNIT MANAGERS ON TEAM EFFECTIVENESS: Mediating Effects of Organizational Communication Satisfaction. This study identifies the effects of the educational leadership of nursing unit managers on team effectiveness and the mediating effects of organizational communication satisfaction; it highlights the importance of educational leadership and organizational communication and provides the data needed to enhance the education capacity of managers. The participants were 216 nursing unit managers of staff nurses at a tertiary hospital located in C Region, South Korea, and nurses who had worked for more than six months at the same hospital. This study was conducted using questionnaires on educational leadership, team effectiveness, and organizational communication satisfaction. Data analysis was performed with a t-test, ANOVA, Scheffé, Pearson's correlation coefficient, and simple and multiple regression analyses using SPSS version 23.0. Mediation analysis was tested using Baron and Kenny's regression analysis and a Sobel test. The mean score for the educational leadership of nursing unit managers was 3.74(±0.68); for organizational communication satisfaction, 3.14(±0.51); and for team effectiveness, 3.52(±0.49). Educational leadership was significantly positively correlated with team effectiveness and organizational communication satisfaction. Organizational communication satisfaction demonstrated a complete mediating effect on the relationship between educational leadership and team effectiveness (β=.61, pcommunication satisfaction among nurses; this supports the idea that educational leadership can contribute to team effectiveness. This suggests that the educational leadership and communication capacity of nursing unit managers must be improved to enhance the performance of nursing organizations. Copyright © 2018. Published by Elsevier B.V.

The different ways through which specificity works in orthosteric and allosteric drugs.

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Nussinov, Ruth; Tsai, Chung-Jung

2012-01-01

Currently, there are two types of drugs on the market: orthosteric, which bind at the active site; and allosteric, which bind elsewhere on the protein surface, and allosterically change the conformation of the protein binding site. In this perspective we argue that the different mechanisms through which the two drug types affect protein activity and their potential pitfalls call for different considerations in drug design. The key problem facing orthosteric drugs is side effects which can occur by drug binding to homologous proteins sharing a similar binding site. Hence, orthosteric drugs should have very high affinity to the target; this would allow a low dosage to selectively achieve the goal of target-only binding. By contrast, allosteric drugs work by shifting the free energy landscape. Their binding to the protein surface perturbs the protein surface atoms, and the perturbation propagates like waves, finally reaching the binding site. Effective drugs should have atoms in good contact with the 'right' protein atoms; that is, the contacts should elicit propagation waves optimally reaching the protein binding site target. While affinity is important, the design should consider the protein conformational ensemble and the preferred propagation states. We provide examples from functional in vivo scenarios for both types of cases, and suggest how high potency can be achieved in allosteric drug development.

Breaching or building social boundaries? : SIDE-effects of computer-mediated communication

NARCIS (Netherlands)

Postmes, T; Spears, R; Lea, M

1998-01-01

Computer-mediated communication (CMC) is sometimes heralded for its power to break down social boundaries and to liberate individuals from social influence, group pressure, and status and power differentials that characterize much face-to-face interaction. We review research conducted within the

Interactive uncertainty reduction strategies and verbal affection in computer-mediated communication

NARCIS (Netherlands)

Antheunis, M.L.; Schouten, A.P.; Valkenburg, P.M.; Peter, J.

2012-01-01

The goal of this study was to investigate the language-based strategies that computer-mediated communication (CMC) users employ to reduce uncertainty in the absence of nonverbal cues. Specifically, this study investigated the prevalence of three interactive uncertainty reduction strategies (i.e.,

THE ROLE OF CUSTOMER SATISFACTION IN MEDIATING MARKETING COMMUNICATION EFFECT ON CUSTOMER LOYALTY

OpenAIRE

Mohamad Dimyati,

2015-01-01

This study aims to test the effect of a) marketing communication on customer satisfaction; b) marketing communication on customer loyalty; c) customer satisfaction on customer loyalty; and d) to identify the role of customer satisfaction in mediating marketing communication effect on customer loyalty of the IM3 user community in Jember regency, East Java province. The study was designed in a form confirmatory research, with the whole IM3 community members in the regency as the ...

An Integrated Review of Emoticons in Computer-Mediated Communication.

Science.gov (United States)

Aldunate, Nerea; González-Ibáñez, Roberto

2016-01-01

Facial expressions constitute a rich source of non-verbal cues in face-to-face communication. They provide interlocutors with resources to express and interpret verbal messages, which may affect their cognitive and emotional processing. Contrarily, computer-mediated communication (CMC), particularly text-based communication, is limited to the use of symbols to convey a message, where facial expressions cannot be transmitted naturally. In this scenario, people use emoticons as paralinguistic cues to convey emotional meaning. Research has shown that emoticons contribute to a greater social presence as a result of the enrichment of text-based communication channels. Additionally, emoticons constitute a valuable resource for language comprehension by providing expressivity to text messages. The latter findings have been supported by studies in neuroscience showing that particular brain regions involved in emotional processing are also activated when people are exposed to emoticons. To reach an integrated understanding of the influence of emoticons in human communication on both socio-cognitive and neural levels, we review the literature on emoticons in three different areas. First, we present relevant literature on emoticons in CMC. Second, we study the influence of emoticons in language comprehension. Finally, we show the incipient research in neuroscience on this topic. This mini review reveals that, while there are plenty of studies on the influence of emoticons in communication from a social psychology perspective, little is known about the neurocognitive basis of the effects of emoticons on communication dynamics.

O2-mediated oxidation of ferrous nitrosylated human serum heme-albumin is limited by nitrogen monoxide dissociation

International Nuclear Information System (INIS)

Ascenzi, Paolo; Gullotta, Francesca; Gioia, Magda; Coletta, Massimo; Fasano, Mauro

2011-01-01

Research highlights: → Human serum heme-albumin displays globin-like properties. → O 2 -mediated oxidation of ferrous nitrosylated human serum heme-albumin. → Allosteric modulation of human serum heme-albumin reactivity. → Rifampicin is an allosteric effector of human serum heme-albumin. → Human serum heme-albumin is a ROS and NOS scavenger. -- Abstract: Human serum heme-albumin (HSA-heme-Fe) displays globin-like properties. Here, kinetics of O 2 -mediated oxidation of ferrous nitrosylated HSA-heme-Fe (HSA-heme-Fe(II)-NO) is reported. Values of the first-order rate constants for O 2 -mediated oxidation of HSA-heme-Fe(II)-NO (i.e., for ferric HSA-heme-Fe formation) and for NO dissociation from HSA-heme-Fe(II)-NO (i.e., for NO replacement by CO) are k = 9.8 x 10 -5 and 8.3 x 10 -4 s -1 , and h = 1.3 x 10 -4 and 8.5 x 10 -4 s -1 , in the absence and presence of rifampicin, respectively, at pH = 7.0 and T = 20.0 o C. The coincidence of values of k and h indicates that NO dissociation represents the rate limiting step of O 2 -mediated oxidation of HSA-heme-Fe(II)-NO. Mixing HSA-heme-Fe(II)-NO with O 2 does not lead to the formation of the transient adduct(s), but leads to the final ferric HSA-heme-Fe derivative. These results reflect the fast O 2 -mediated oxidation of ferrous HSA-heme-Fe and highlight the role of drugs in modulating allosterically the heme-Fe-atom reactivity.

Evolution of allosteric regulation in chorismate mutases from early plants

Energy Technology Data Exchange (ETDEWEB)

Kroll, Kourtney; Holland, Cynthia K.; Starks, Courtney M.; Jez, Joseph M.

2017-09-28

Plants, fungi, and bacteria synthesize the aromatic amino acids: l-phenylalanine, l-tyrosine, and l-tryptophan. Chorismate mutase catalyzes the branch point reaction of phenylalanine and tyrosine biosynthesis to generate prephenate. In Arabidopsis thaliana, there are two plastid-localized chorismate mutases that are allosterically regulated (AtCM1 and AtCM3) and one cytosolic isoform (AtCM2) that is unregulated. Previous analysis of plant chorismate mutases suggested that the enzymes from early plants (i.e. bryophytes/moss, lycophytes, and basal angiosperms) formed a clade distinct from the isoforms found in flowering plants; however, no biochemical information on these enzymes is available. To understand the evolution of allosteric regulation in plant chorismate mutases, we analyzed a basal lineage of plant enzymes homologous to AtCM1 based on sequence similarity. The chorismate mutases from the moss/bryophyte Physcomitrella patens (PpCM1 and PpCM2), the lycophyte Selaginella moellendorffii (SmCM), and the basal angiosperm Amborella trichopoda (AmtCM1 and AmtCM2) were characterized biochemically. Tryptophan was a positive effector for each of the five enzymes examined. Histidine was a weak positive effector for PpCM1 and AmtCM1. Neither tyrosine nor phenylalanine altered the activity of SmCM; however, tyrosine was a negative regulator of the other four enzymes. Phenylalanine down-regulates both moss enzymes and AmtCM2. The 2.0 Å X-ray crystal structure of PpCM1 in complex with the tryptophan identified the allosteric effector site and reveals structural differences between the R- (more active) and T-state (less active) forms of plant chorismate mutases. Molecular insight into the basal plant chorismate mutases guides our understanding of the evolution of allosteric regulation in these enzymes.

Mediate evaluation of replicating a Training Program in Nonverbal Communication in Gerontology

Directory of Open Access Journals (Sweden)

Teresa Cristina Gioia Schimidt

2015-04-01

Full Text Available OBJECTIVE Replicating the training program in non-verbal communication based on the theoretical framework of interpersonal communication; non-verbal coding, valuing the aging aspects in the perspective of active aging, checking its current relevance through the content assimilation index after 90 days (mediate of its application. METHOD A descriptive and exploratory field study was conducted in three hospitals under direct administration of the state of São Paulo that caters exclusively to Unified Health System (SUS patients. The training lasted 12 hours divided in three meetings, applied to 102 health professionals. RESULTS Revealed very satisfactory and satisfactory mediate content assimilation index in 82.9%. CONCLUSION The program replication proved to be relevant and updated the setting of hospital services, while remaining efficient for healthcare professionals.

Structure of CC chemokine receptor 2 with orthosteric and allosteric antagonists

Energy Technology Data Exchange (ETDEWEB)

Zheng, Yi; Qin, Ling; Ortiz Zacarías, Natalia V.; de Vries, Henk; Han, Gye Won; Gustavsson, Martin; Dabros, Marta; Zhao, Chunxia; Cherney, Robert J.; Carter, Percy; Stamos, Dean; Abagyan, Ruben; Cherezov, Vadim; Stevens, Raymond C.; IJzerman, Adriaan P.; Heitman, Laura H.; Tebben, Andrew; Kufareva, Irina; Handel , Tracy M. (Vertex Pharm); (Leiden-MC); (USC); (BMS); (UCSD)

2016-12-07

CC chemokine receptor 2 (CCR2) is one of 19 members of the chemokine receptor subfamily of human class A G-protein-coupled receptors. CCR2 is expressed on monocytes, immature dendritic cells, and T-cell subpopulations, and mediates their migration towards endogenous CC chemokine ligands such as CCL2 (ref. 1). CCR2 and its ligands are implicated in numerous inflammatory and neurodegenerative diseases2 including atherosclerosis, multiple sclerosis, asthma, neuropathic pain, and diabetic nephropathy, as well as cancer3. These disease associations have motivated numerous preclinical studies and clinical trials4 (see http://www.clinicaltrials.gov) in search of therapies that target the CCR2–chemokine axis. To aid drug discovery efforts5, here we solve a structure of CCR2 in a ternary complex with an orthosteric (BMS-681 (ref. 6)) and allosteric (CCR2-RA-[R]7) antagonist. BMS-681 inhibits chemokine binding by occupying the orthosteric pocket of the receptor in a previously unseen binding mode. CCR2-RA-[R] binds in a novel, highly druggable pocket that is the most intracellular allosteric site observed in class A G-protein-coupled receptors so far; this site spatially overlaps the G-protein-binding site in homologous receptors. CCR2-RA-[R] inhibits CCR2 non-competitively by blocking activation-associated conformational changes and formation of the G-protein-binding interface. The conformational signature of the conserved microswitch residues observed in double-antagonist-bound CCR2 resembles the most inactive G-protein-coupled receptor structures solved so far. Like other protein–protein interactions, receptor–chemokine complexes are considered challenging therapeutic targets for small molecules, and the present structure suggests diverse pocket epitopes that can be exploited to overcome obstacles in drug design.

Computer-mediated communication and interpersonal attraction: an experimental test of two explanatory hypotheses.

Science.gov (United States)

Antheunis, Marjolijn L; Valkenburg, Patti M; Peter, Jochen

2007-12-01

The aims of this study were (a) to investigate the influence of computer-mediated communication (CMC) on interpersonal attraction and (b) to examine two underlying processes in the CMC-interpersonal attraction relationship. We identified two variables that may mediate the influence of CMC on interpersonal attraction: self-disclosure and direct questioning. Focusing on these potential mediating variables, we tested two explanatory hypotheses: the CMC-induced direct questioning hypothesis and the CMC-induced self-disclosure hypothesis. Eighty-one cross-sex dyads were randomly assigned to one of three experimental conditions: text-only CMC, visual CMC, and face-to-face communication. We did not find a direct effect of CMC on interpersonal attraction. However, we did find two positive indirect effects of text-only CMC on interpersonal attraction: text-only CMC stimulated both self-disclosure and direct questioning, both of which in turn enhanced interpersonal attraction. Results are discussed in light of uncertainty reduction theory and CMC theories.

THE METAPHOR OF “VOICE” IN COMPUTER-MEDIATED COMMUNICATION

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CAMELIA GRĂDINARU

2016-11-01

Full Text Available This paper stresses some significant ways in which the voice appears in the new media studies. Whether as a dominant metaphor in the early stages of computer-mediated communication, whether in opposition with silence or listening, whether as an important component of the participatory culture, the voice remains a key concept and a helpful lens trough which the communicative, social, and cultural parts of the digital era are illuminated. In these processes, the “digital” voice is conceived as a powerful tool that can be easily heard and disseminated, in spite of the obvious limitation of its strengths or of its access. Thus, the rethinking of voice in contemporary frame brings at surface the issues of politics of voice and also ethical challenges.

Family Communication Patterns and Relational Maintenance Behavior: Direct and Mediated Associations with Friendship Closeness

Science.gov (United States)

Ledbetter, Andrew M.

2009-01-01

In this study, both face-to-face and online relational maintenance behaviors were tested as mediators of family communication patterns and closeness with a same-sex friend. Participants included 417 young adults recruited from communication courses at a large university in the Midwestern United States. The obtained structural model demonstrated…

The Application of Intentional Subjective Properties and Mediated Communication Tools to Software Agents in Online Disputes Resolution Environments

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Renzo Gobbin

2004-11-01

Full Text Available This paper examines the use of subjective properties in modeling an architecture for cooperative agents using Agent Communication Language (ACL that is used as a mediating tool for cooperative communication activities between and within software agents. The role that subjective and objective properties have in explaining and modeling agent internalization and externalization of ACL messages is investigated and related to Vygotsky’s developmental learning theories such as Mediated Activity Theory. A novel agent architecture ALMA (Agent Language Mediated Activity based on the integration of agents’ subjective and objective properties within an agent communication activity framework will be presented. The relevance of software agents subjective properties in modeling applications such as e-Law Online Dispute Resolution for e-business contractual arrangements using natural language subject/object relation in their communication patterns will be discussed.

SH2-catalytic domain linker heterogeneity influences allosteric coupling across the SFK family.

Science.gov (United States)

Register, A C; Leonard, Stephen E; Maly, Dustin J

2014-11-11

Src-family kinases (SFKs) make up a family of nine homologous multidomain tyrosine kinases whose misregulation is responsible for human disease (cancer, diabetes, inflammation, etc.). Despite overall sequence homology and identical domain architecture, differences in SH3 and SH2 regulatory domain accessibility and ability to allosterically autoinhibit the ATP-binding site have been observed for the prototypical SFKs Src and Hck. Biochemical and structural studies indicate that the SH2-catalytic domain (SH2-CD) linker, the intramolecular binding epitope for SFK SH3 domains, is responsible for allosterically coupling SH3 domain engagement to autoinhibition of the ATP-binding site through the conformation of the αC helix. As a relatively unconserved region between SFK family members, SH2-CD linker sequence variability across the SFK family is likely a source of nonredundant cellular functions between individual SFKs via its effect on the availability of SH3 and SH2 domains for intermolecular interactions and post-translational modification. Using a combination of SFKs engineered with enhanced or weakened regulatory domain intramolecular interactions and conformation-selective inhibitors that report αC helix conformation, this study explores how SH2-CD sequence heterogeneity affects allosteric coupling across the SFK family by examining Lyn, Fyn1, and Fyn2. Analyses of Fyn1 and Fyn2, isoforms that are identical but for a 50-residue sequence spanning the SH2-CD linker, demonstrate that SH2-CD linker sequence differences can have profound effects on allosteric coupling between otherwise identical kinases. Most notably, a dampened allosteric connection between the SH3 domain and αC helix leads to greater autoinhibitory phosphorylation by Csk, illustrating the complex effects of SH2-CD linker sequence on cellular function.

Learners' Perceived Information Overload in Online Learning via Computer-Mediated Communication

Science.gov (United States)

Chen, Chun-Ying; Pedersen, Susan; Murphy, Karen L.

2011-01-01

Many studies report information overload as one of the main problems that students encounter in online learning via computer-mediated communication. This study aimed to explore the sources of online students' information overload and offer suggestions for increasing students' cognitive resources for learning. Participants were 12 graduate students…

Preventing and De-Escalating Ethical Conflict: A Communication-Training Mediation Model.

Science.gov (United States)

Levin, Tomer T; Parker, Patricia A

2015-01-01

While ethical conflicts in the provision of healthcare are common, the current third-party mediator model is limited by a lack of expert ethical mediators, who are often not on site when conflict escalates. In order to improve clinical outcomes in situations such as conflicts at the end of life, we suggest that clinicians-physicians, nurses and social workers-be trained to prevent and de-escalate emerging conflicts. This can be achieved using a mediation model framed by a communication-training approach. A case example is presented and the model is discussed. The implication of this preventative/early intervention model for improving clinical outcomes, in particular end-of life conflict, is considered. Copyright 2015 The Journal of Clinical Ethics. All rights reserved.

Defying c-Abl signaling circuits through small allosteric compounds

Directory of Open Access Journals (Sweden)

Stefania eGonfloni

2014-11-01

Full Text Available Many extracellular and intracellular signals promote the c-Abl tyrosine kinase activity. c-Abl in turn triggers a multitude of changes either in protein phosphorylation or in gene expression in the cell. Yet, c-Abl takes part in diverse signaling routes because of several domains linked to its catalytic core. Complex conformational changes turn on and off its kinase activity. These changes affect surface features of the c-Abl kinase and likely its capability to bind actin and/or DNA. Two specific inhibitors (ATP-competitive or allosteric compounds regulate the c-Abl kinase through different mechanisms. NMR studies show that a c-Abl fragment (SH3-SH2-linker-SH1 adopts different conformational states upon binding to each inhibitor. This supports an unconventional use for allosteric compounds to unraveling physiological c-Abl signaling circuits.

The Disclosure-Intimacy Link in Computer-Mediated Communication: An Attributional Extension of the Hyperpersonal Model

Science.gov (United States)

Jiang, L. Crystal; Bazarova, Natalie N.; Hancock, Jeffrey T.

2011-01-01

The present research investigated whether the attribution process through which people explain self-disclosures differs in text-based computer-mediated interactions versus face to face, and whether differences in causal attributions account for the increased intimacy frequently observed in mediated communication. In the experiment participants…

Brief Report: Mediation of Treatment Effect in a Communication Intervention for Pre-School Children with Autism

Science.gov (United States)

Aldred, Catherine; Green, Jonathan; Emsley, Richard; McConachie, Helen

2012-01-01

Tests of mediation in treatment trials can illuminate processes of change and suggest causal influences in development. We conducted a mediation analysis of a previously published randomised controlled trial of parent-mediated communication-focused treatment for autism against ordinary care, with 28 children aged 2-5 years (Aldred et al. in J…

Anxiety about speaking a foreign language as a mediator of the relation between motivation and willingness to communicate.

Science.gov (United States)

Wu, Chia-Pei; Lin, Huey-Ju

2014-12-01

The purpose of this study was to examine whether anxiety about speaking a foreign language mediated the relation between motivation and a willingness to communicate among 107 Taiwanese students sampled from two public universities and one private university. A regression analysis indicated that motivation was negatively related to university students' anxiety about speaking a foreign language and positively related to willingness to communicate. Furthermore, anxiety about speaking a foreign language was negatively related to university students' willingness to communicate, and also partially mediated the relationship between motivation and willingness to communicate. The findings suggest that high motivation and low anxiety about speaking a foreign language are needed for Taiwanese students to demonstrate a stronger willingness to communicate.

Molecular dynamics simulation study of PTP1B with allosteric inhibitor and its application in receptor based pharmacophore modeling

Science.gov (United States)

Bharatham, Kavitha; Bharatham, Nagakumar; Kwon, Yong Jung; Lee, Keun Woo

2008-12-01

Allosteric inhibition of protein tyrosine phosphatase 1B (PTP1B), has paved a new path to design specific inhibitors for PTP1B, which is an important drug target for the treatment of type II diabetes and obesity. The PTP1B1-282-allosteric inhibitor complex crystal structure lacks α7 (287-298) and moreover there is no available 3D structure of PTP1B1-298 in open form. As the interaction between α7 and α6-α3 helices plays a crucial role in allosteric inhibition, α7 was modeled to the PTP1B1-282 in open form complexed with an allosteric inhibitor (compound-2) and a 5 ns MD simulation was performed to investigate the relative orientation of the α7-α6-α3 helices. The simulation conformational space was statistically sampled by clustering analyses. This approach was helpful to reveal certain clues on PTP1B allosteric inhibition. The simulation was also utilized in the generation of receptor based pharmacophore models to include the conformational flexibility of the protein-inhibitor complex. Three cluster representative structures of the highly populated clusters were selected for pharmacophore model generation. The three pharmacophore models were subsequently utilized for screening databases to retrieve molecules containing the features that complement the allosteric site. The retrieved hits were filtered based on certain drug-like properties and molecular docking simulations were performed in two different conformations of protein. Thus, performing MD simulation with α7 to investigate the changes at the allosteric site, then developing receptor based pharmacophore models and finally docking the retrieved hits into two distinct conformations will be a reliable methodology in identifying PTP1B allosteric inhibitors.

Face-to-face versus computer-mediated communication in a primary school setting

NARCIS (Netherlands)

Meijden, H.A.T. van der; Veenman, S.A.M.

2005-01-01

Computer-mediated communication is increasingly being used to support cooperative problem solving and decision making in schools. Despite the large body of literature on cooperative or collaborative learning, few studies have explicitly compared peer learning in face-to-face (FTF) versus

Swift Guanxi in online marketplace : The role of computer-mediated-communication technologies

NARCIS (Netherlands)

Ou, C.X.J.; Pavlou, P.A.; Davison, R.M.

2014-01-01

The concept of guanxi (i.e., a close and pervasive interpersonal relationship) has received little attention in the literature on online marketplaces, perhaps due to their impersonal nature. However, we propose that computer-mediated communication (CMC) technologies can mimic traditional interactive

Speaker transfer in children's peer conversation: completing communication-aid-mediated contributions.

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Clarke, Michael; Bloch, Steven; Wilkinson, Ray

2013-03-01

Managing the exchange of speakers from one person to another effectively is a key issue for participants in everyday conversational interaction. Speakers use a range of resources to indicate, in advance, when their turn will come to an end, and listeners attend to such signals in order to know when they might legitimately speak. Using the principles and findings from conversation analysis, this paper examines features of speaker transfer in a conversation between a boy with cerebral palsy who has been provided with a voice-output communication aid (VOCA), and a peer without physical or communication difficulties. Specifically, the analysis focuses on turn exchange, where a VOCA-mediated contribution approach completion, and the child without communication needs is due to speak next.

Selective Negative Allosteric Modulation Of Metabotropic Glutamate Receptors - A Structural Perspective of Ligands and Mutants

DEFF Research Database (Denmark)

Harpsøe, Kasper; Isberg, Vignir; Tehan, Benjamin G

2015-01-01

modulators. In this analysis, we make the first comprehensive structural comparison of all metabotropic glutamate receptors, placing selective negative allosteric modulators and critical mutants into the detailed context of the receptor binding sites. A better understanding of how the different m......Glu allosteric modulator binding modes relates to selective pharmacological actions will be very valuable for rational design of safer drugs....

Mediatisation or PR-ization of Public--Media Communication--Analysis of Mediated Communication of Zoran Milanović.

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Tanta, Ivan; Lesinger, Gordana

2015-12-01

Politicians and their public relations advisors depend on the mass communication media to transmit messages dailyand communicate effectively. The development of the mass media, from traditional to new, has changed the working conditions of these professions where one inevitably affects the other. Consequently, the way of formatting information in the newshas changed, along with the way of monitoring the political developments and informs the public on political activities. Amajor role in this process, over and above the political actors, has advisers for public relations, who choose moments andevents to publicise (PR-ization). With the increasing influence of public relations to media reports, politics also changes thepicture of the media and the impact on media coverage. Similarly, the impact on the manner in which the media reportprocess, what topics will be discussed topics and what tone the given information will have. We are living in a world characterized by mediation (Mazzoleni and Schulz, 1999) of the politics and the society as a whole, because politics and publicrelations necessarily need the media to communicate with their audiences. In this regard, we can talk about PR-izationmedia as the fundamental role of public relations practitioners affect attitudes, which skillfully make careful design ofmessages and events that are not included herein are the three professions each other should one without the other does notmake sense. This paper will focus on the influence of the media on politics and on influence of the public relations as profession in the content media perception. In view of the drawn by daily public appearances of Prime Minister, Zoran Milanovi6,and as says Lali63 few politics-related phenomena have over the past twenty years engaged so many reviews by experts andscholars as the Prime Minister's rhetoric. The particular form of the political communication will be reviewed in this paper.Through the interviews and the content analysis of key

Organizational culture and a safety-conscious work environment: The mediating role of employee communication satisfaction.

Science.gov (United States)

Silla, Inmaculada; Navajas, Joaquin; Koves, G Kenneth

2017-06-01

A safety-conscious work environment allows high-reliability organizations to be proactive regarding safety and enables employees to feel free to report any concern without fear of retaliation. Currently, research on the antecedents to safety-conscious work environments is scarce. Structural equation modeling was applied to test the mediating role of employee communication satisfaction in the relationship between constructive culture and a safety-conscious work environment in several nuclear power plants. Employee communication satisfaction partially mediated the positive relationships between a constructive culture and a safety-conscious work environment. Constructive cultures in which cooperation, supportive relationships, individual growth and high performance are encouraged facilitate the establishment of a safety-conscious work environment. This influence is partially explained by increased employee communication satisfaction. Constructive cultures should be encouraged within organizations. In addition, managers should promote communication policies and practices that support a safety-conscious work environment. Copyright © 2017 Elsevier Ltd and National Safety Council. All rights reserved.

Steric hindrance mutagenesis in the conserved extracellular vestibule impedes allosteric binding of antidepressants to the serotonin transporter

DEFF Research Database (Denmark)

Plenge, Per; Shi, Lei; Beuming, Thijs

2012-01-01

be involved in the allosteric binding in the extracellular vestibule located above the central substrate binding (S1) site. Indeed, mutagenesis of selected residues in the vestibule reduces the allosteric potency of (S)-citalopram and clomipramine. The identified site is further supported by the inhibitory...

AIM for Allostery: Using the Ising Model to Understand Information Processing and Transmission in Allosteric Biomolecular Systems.

Science.gov (United States)

LeVine, Michael V; Weinstein, Harel

2015-05-01

In performing their biological functions, molecular machines must process and transmit information with high fidelity. Information transmission requires dynamic coupling between the conformations of discrete structural components within the protein positioned far from one another on the molecular scale. This type of biomolecular "action at a distance" is termed allostery . Although allostery is ubiquitous in biological regulation and signal transduction, its treatment in theoretical models has mostly eschewed quantitative descriptions involving the system's underlying structural components and their interactions. Here, we show how Ising models can be used to formulate an approach to allostery in a structural context of interactions between the constitutive components by building simple allosteric constructs we termed Allosteric Ising Models (AIMs). We introduce the use of AIMs in analytical and numerical calculations that relate thermodynamic descriptions of allostery to the structural context, and then show that many fundamental properties of allostery, such as the multiplicative property of parallel allosteric channels, are revealed from the analysis of such models. The power of exploring mechanistic structural models of allosteric function in more complex systems by using AIMs is demonstrated by building a model of allosteric signaling for an experimentally well-characterized asymmetric homodimer of the dopamine D2 receptor.

Biased signaling of lipids and allosteric actions of synthetic molecules for GPR119

DEFF Research Database (Denmark)

Hassing, Helle A; Fares, Suzan; Larsen, Olav

2016-01-01

for 2h with the 2-MAG-lipase inhibitor JZL84 doubled the constitutive activity, indicating that endogenous lipids contribute to the apparent constitutive activity. Finally, besides being an agonist, AR231453 acted as a positive allosteric modulator of OEA and increased its potency by 54-fold at 100nM AR......231453. Our studies uncovering broad and biased signaling, masked constitutive activity by endogenous MAGs, and ago-allosteric properties of synthetic ligands may explain why many GPR119 drug-discovery programs have failed so far....

New screening strategy and analysis for identification of allosteric modulators for glucagon-like peptide-1 receptor using GLP-1 (9-36) amide.

Science.gov (United States)

Nakane, Atsushi; Gotoh, Yusuke; Ichihara, Junji; Nagata, Hidetaka

2015-12-15

The glucagon-like peptide-1 receptor (GLP-1R) is an important physiologic regulator of insulin secretion and a major therapeutic target for diabetes mellitus. GLP-1 (7-36) amide (active form of GLP-1) is truncated to GLP-1 (9-36) amide, which has been described as a weak agonist of GLP-1R and the major form of GLP-1 in the circulation. New classes of positive allosteric modulators (PAMs) for GLP-1R may offer improved therapeutic profiles. To identify these new classes, we developed novel and robust primary and secondary high-throughput screening (HTS) systems in which PAMs were identified to enhance the GLP-1R signaling induced by GLP-1 (9-36) amide. Screening enabled identification of two compounds, HIT-465 and HIT-736, which possessed new patterns of modulation of GLP-1R. We investigated the ability of these compounds to modify GLP-1R signaling enhanced GLP-1 (9-36) amide- and/or GLP-1 (7-36) amide-mediated cyclic adenosine monophosphate (cAMP) accumulation. These compounds also had unique profiles with regard to allosteric modulation of multiple downstream signaling (PathHunter β-arrestin signaling, PathHunter internalization signaling, microscopy-based internalization assay). We found allosteric modulation patterns to be obviously different among HIT-465, HIT-736, and Novo Nordisk compound 2. This work may enable the design of new classes of drug candidates by targeting modulation of GLP-1 (7-36) amide and GLP-1 (9-36) amide. Copyright © 2015 Elsevier Inc. All rights reserved.

Computer-Mediated Communication with Distant Friends: Relations with Adjustment during Students' First Semester in College

Science.gov (United States)

Ranney, John D.; Troop-Gordon, Wendy

2012-01-01

Because of recent technological innovations, college freshmen can readily communicate with friends who they see infrequently (e.g., friends from home). The current study addressed whether computer-mediated communication with these distant friends can compensate for a lack of high-quality on-campus friendships during students' first semester of…

Gap-junction-mediated communication in human periodontal ligament cells.

Science.gov (United States)

Kato, R; Ishihara, Y; Kawanabe, N; Sumiyoshi, K; Yoshikawa, Y; Nakamura, M; Imai, Y; Yanagita, T; Fukushima, H; Kamioka, H; Takano-Yamamoto, T; Yamashiro, T

2013-07-01

Periodontal tissue homeostasis depends on a complex cellular network that conveys cell-cell communication. Gap junctions (GJs), one of the intercellular communication systems, are found between adjacent human periodontal ligament (hPDL) cells; however, the functional GJ coupling between hPDL cells has not yet been elucidated. In this study, we investigated functional gap-junction-mediated intercellular communication in isolated primary hPDL cells. SEM images indicated that the cells were in contact with each other via dendritic processes, and also showed high anti-connexin43 (Cx43) immunoreactivity on these processes. Gap-junctional intercellular communication (GJIC) among hPDL cells was assessed by fluorescence recovery after a photobleaching (FRAP) analysis, which exhibited dye coupling between hPDL cells, and was remarkably down-regulated when the cells were treated with a GJ blocker. Additionally, we examined GJs under hypoxic stress. The fluorescence recovery and expression levels of Cx43 decreased time-dependently under the hypoxic condition. Exposure to GJ inhibitor or hypoxia increased RANKL expression, and decreased OPG expression. This study shows that GJIC is responsible for hPDL cells and that its activity is reduced under hypoxia. This is consistent with the possible role of hPDL cells in regulating the biochemical reactions in response to changes in the hypoxic environment.

Learners' perceived information overload in online learning via computer-mediated communication

Directory of Open Access Journals (Sweden)

Karen L. Murphy

2011-12-01

Full Text Available Many studies report information overload as one of the main problems that students encounter in online learning via computer-mediated communication. This study aimed to explore the sources of online students' information overload and offer suggestions for increasing students' cognitive resources for learning. Participants were 12 graduate students from two online courses in the United States. Their learning experiences in both online discussions and on the course website were explored through semi-structured interviews. They also completed a background questionnaire that assessed three constructs that limit learner readiness and are likely to lead to online students' perceived information overload: inadequate prior knowledge, inadequate English proficiency, and lack of technical skills for participating in computer-mediated communications. The findings suggest that varied learner characteristics led some students to be more susceptible than others to information overload. Emerging data-driven risk factors were: lack of efficiency in reading from computer screens, visual and auditory learning preferences, and time constraints. Difficulties associated with students' perceptions of information overload are addressed and implications for course design are offered.

Establishing an Empirical Link between Computer-Mediated Communication (CMC) and SLA: A Meta-Analysis of the Research

Science.gov (United States)

Lin, Huifen

2014-01-01

Drawing on interactionist and socio-cultural theories, tools provided in computer-mediated communication (CMC) environments have long been considered able to create an environment that shares many communicative features with face-to-face communication. Over the past two decades, researchers have employed a variety of strategies to examine the…

The Conformational Dynamics of Cas9 Governing DNA Cleavage Are Revealed by Single-Molecule FRET

Directory of Open Access Journals (Sweden)

Mengyi Yang

2018-01-01

Full Text Available Summary: Off-target binding and cleavage by Cas9 pose major challenges in its application. How the conformational dynamics of Cas9 govern its nuclease activity under on- and off-target conditions remains largely unknown. Here, using intra-molecular single-molecule fluorescence resonance energy transfer measurements, we revealed that Cas9 in apo, sgRNA-bound, and dsDNA/sgRNA-bound forms spontaneously transits among three major conformational states, mainly reflecting significant conformational mobility of the catalytic HNH domain. We also uncovered surprising long-range allosteric communication between the HNH domain and the RNA/DNA heteroduplex at the PAM-distal end to ensure correct positioning of the catalytic site, which demonstrated that a unique proofreading mechanism served as the last checkpoint before DNA cleavage. Several Cas9 residues were likely to mediate the allosteric communication and proofreading step. Modulating interactions between Cas9 and heteroduplex at the PAM-distal end by introducing mutations on these sites provides an alternative route to improve and optimize the CRISPR/Cas9 toolbox. : Yang et al. revealed significant conformational dynamics of Cas9 at global and local scales using single-molecule FRET. They uncovered surprising long-range allosteric communication between the HNH nuclease domain and the RNA/DNA heteroduplex at the PAM-distal end that serves as a proofreading checkpoint to govern the nuclease activity and specificity of Cas9. Keywords: CRISPR, Cas9, single-molecule, FRET, conformational dynamics, proofreading, off-target, allosteric communication, genome editing

Musicians Crossing Musical Instrument Gender Stereotypes: A Study of Computer-Mediated Communication

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Abeles, Harold F.; Hafeli, Mary; Sears, Colleen

2014-01-01

This study examined computer-mediated communication (CMC) -- blogs and responses to YouTube postings -- to better understand how CMCs reflect adolescents' attitudes towards musicians playing instruments that cross gender stereotypes. Employing purposive sampling, we used specific search terms, such as "girl drummer", to identify a…

Orexin A/Hypocretin Modulates Leptin Receptor-Mediated Signaling by Allosteric Modulations Mediated by the Ghrelin GHS-R1A Receptor in Hypothalamic Neurons.

Science.gov (United States)

Medrano, Mireia; Aguinaga, David; Reyes-Resina, Irene; Canela, Enric I; Mallol, Josefa; Navarro, Gemma; Franco, Rafael

2018-06-01

The hypothalamus is a key integrator of nutrient-seeking signals in the form of hormones and metabolites originated in both the central nervous system and the periphery. The main autocrine and paracrine target of orexinergic-related hormones such as leptin, orexin/hypocretin, and ghrelin are neuropeptide Y neurons located in the arcuate nucleus of the hypothalamus. The aim of this study was to investigate the expression and the molecular and functional relationships between leptin, orexin/hypocretin and ghrelin receptors. Biophysical studies in a heterologous system showed physical interactions between them, with potential formation of heterotrimeric complexes. Functional assays showed robust allosteric interactions particularly different when the three receptors are expressed together. Further biochemical and pharmacological assays provided evidence of heterotrimer functional expression in primary cultures of hypothalamic neurons. These findings constitute evidence of close relationships in the action of the three hormones already starting at the receptor level in hypothalamic cells.

Allosteric substrate switching in a voltage-sensing lipid phosphatase.

Science.gov (United States)

Grimm, Sasha S; Isacoff, Ehud Y

2016-04-01

Allostery provides a critical control over enzyme activity, biasing the catalytic site between inactive and active states. We found that the Ciona intestinalis voltage-sensing phosphatase (Ci-VSP), which modifies phosphoinositide signaling lipids (PIPs), has not one but two sequential active states with distinct substrate specificities, whose occupancy is allosterically controlled by sequential conformations of the voltage-sensing domain (VSD). Using fast fluorescence resonance energy transfer (FRET) reporters of PIPs to monitor enzyme activity and voltage-clamp fluorometry to monitor conformational changes in the VSD, we found that Ci-VSP switches from inactive to a PIP3-preferring active state when the VSD undergoes an initial voltage-sensing motion and then into a second PIP2-preferring active state when the VSD activates fully. This two-step allosteric control over a dual-specificity enzyme enables voltage to shape PIP concentrations in time, and provides a mechanism for the complex modulation of PIP-regulated ion channels, transporters, cell motility, endocytosis and exocytosis.

Allosteric substrate switching in a voltage sensing lipid phosphatase

Science.gov (United States)

Grimm, Sasha S.; Isacoff, Ehud Y.

2016-01-01

Allostery provides a critical control over enzyme activity, biasing the catalytic site between inactive and active states. We find the Ciona intestinalis voltage-sensing phosphatase (Ci-VSP), which modifies phosphoinositide signaling lipids (PIPs), to have not one but two sequential active states with distinct substrate specificities, whose occupancy is allosterically controlled by sequential conformations of the voltage sensing domain (VSD). Using fast FRET reporters of PIPs to monitor enzyme activity and voltage clamp fluorometry to monitor conformational changes in the VSD, we find that Ci-VSP switches from inactive to a PIP3-preferring active state when the VSD undergoes an initial voltage sensing motion and then into a second PIP2-preferring active state when the VSD activates fully. This novel 2-step allosteric control over a dual specificity enzyme enables voltage to shape PIP concentrations in time, and provides a mechanism for the complex modulation of PIP-regulated ion channels, transporters, cell motility and endo/exocytosis. PMID:26878552

Zinc as Allosteric Ion Channel Modulator: Ionotropic Receptors as Metalloproteins

Science.gov (United States)

Peralta, Francisco Andrés; Huidobro-Toro, Juan Pablo

2016-01-01

Zinc is an essential metal to life. This transition metal is a structural component of many proteins and is actively involved in the catalytic activity of cell enzymes. In either case, these zinc-containing proteins are metalloproteins. However, the amino acid residues that serve as ligands for metal coordination are not necessarily the same in structural proteins compared to enzymes. While crystals of structural proteins that bind zinc reveal a higher preference for cysteine sulfhydryls rather than histidine imidazole rings, catalytic enzymes reveal the opposite, i.e., a greater preference for the histidines over cysteines for catalysis, plus the influence of carboxylic acids. Based on this paradigm, we reviewed the putative ligands of zinc in ionotropic receptors, where zinc has been described as an allosteric modulator of channel receptors. Although these receptors do not strictly qualify as metalloproteins since they do not normally bind zinc in structural domains, they do transitorily bind zinc at allosteric sites, modifying transiently the receptor channel’s ion permeability. The present contribution summarizes current information showing that zinc allosteric modulation of receptor channels occurs by the preferential metal coordination to imidazole rings as well as to the sulfhydryl groups of cysteine in addition to the carboxyl group of acid residues, as with enzymes and catalysis. It is remarkable that most channels, either voltage-sensitive or transmitter-gated receptor channels, are susceptible to zinc modulation either as positive or negative regulators. PMID:27384555

The relationship between the external environment and physician e-mail communication: The mediating role of health information technology availability.

Science.gov (United States)

Mazurenko, Olena; Hearld, Larry R; Menachemi, Nir

Physician e-mail communication, with patients and other providers, is one of the cornerstones of effective care coordination but varies significantly across physicians. A physician's external environment may contribute to such variations by enabling or constraining a physician's ability to adopt innovations such as health information technology (HIT) that can be used to support e-mail communication. The aim of the study was to examine whether the relationship of the external environment and physician e-mail communication with patients and other providers is mediated by the practice's HIT availability. The data were obtained from the Health Tracking Physician Survey (2008) and the Area Resource File (2008). Cross-sectional multivariable subgroup path analysis was used to investigate the mediating role of HIT availability across 2,850 U.S. physicians. Solo physicians' perceptions about malpractice were associated with 0.97 lower odds (p communication with patients and other providers, as compared to group and hospital practices, even when mediated by HIT availability. Subgroup analyses indicated that different types of practices are responsive to the different dimensions of the external environment. Specifically, solo practitioners were more responsive to the availability of resources in their environment, with per capita income associated with lower likelihood of physician e-mail communication (OR = 0.99, p information technology availability, which in turn was associated with a greater likelihood of communicating via e-mail with patients (OR = 1.02, p communication and the external environment is mediated by the practice's HIT availability. Efforts to improve physician e-mail communication and HIT adoption may need to reflect the varied perceptions of different types of practices.

Targeting S-adenosylmethionine biosynthesis with a novel allosteric inhibitor of Mat2A

Energy Technology Data Exchange (ETDEWEB)

Quinlan, Casey L.; Kaiser, Stephen E.; Bolaños, Ben; Nowlin, Dawn; Grantner, Rita; Karlicek-Bryant, Shannon; Feng, Jun Li; Jenkinson, Stephen; Freeman-Cook, Kevin; Dann, Stephen G.; Wang, Xiaoli; Wells, Peter A.; Fantin, Valeria R.; Stewart, Al E.; Grant, Stephan K. (Pfizer)

2017-05-29

S-Adenosyl-L-methionine (SAM) is an enzyme cofactor used in methyl transfer reactions and polyamine biosynthesis. The biosynthesis of SAM from ATP and L-methionine is performed by the methionine adenosyltransferase enzyme family (Mat; EC 2.5.1.6). Human methionine adenosyltransferase 2A (Mat2A), the extrahepatic isoform, is often deregulated in cancer. We identified a Mat2A inhibitor, PF-9366, that binds an allosteric site on Mat2A that overlaps with the binding site for the Mat2A regulator, Mat2B. Studies exploiting PF-9366 suggested a general mode of Mat2A allosteric regulation. Allosteric binding of PF-9366 or Mat2B altered the Mat2A active site, resulting in increased substrate affinity and decreased enzyme turnover. These data support a model whereby Mat2B functions as an inhibitor of Mat2A activity when methionine or SAM levels are high, yet functions as an activator of Mat2A when methionine or SAM levels are low. The ramification of Mat2A activity modulation in cancer cells is also described.

Trolling in asynchronous computer-mediated communication:\\ud From user discussions to academic definitions

OpenAIRE

Hardaker, Claire

2010-01-01

Whilst computer-mediated communication (CMC) can benefit users by providing quick and easy communication between those separated by time and space, it can also provide varying degrees of anonymity that may encourage a sense of impunity and freedom from being held accountable for\\ud inappropriate online behaviour. As such, CMC is a fertile ground for studying impoliteness, whether it occurs in response to perceived threat (flaming), or as an end in its own right (trolling). Currently, first an...

Sparse networks of directly coupled, polymorphic, and functional side chains in allosteric proteins.

Science.gov (United States)

Soltan Ghoraie, Laleh; Burkowski, Forbes; Zhu, Mu

2015-03-01

Recent studies have highlighted the role of coupled side-chain fluctuations alone in the allosteric behavior of proteins. Moreover, examination of X-ray crystallography data has recently revealed new information about the prevalence of alternate side-chain conformations (conformational polymorphism), and attempts have been made to uncover the hidden alternate conformations from X-ray data. Hence, new computational approaches are required that consider the polymorphic nature of the side chains, and incorporate the effects of this phenomenon in the study of information transmission and functional interactions of residues in a molecule. These studies can provide a more accurate understanding of the allosteric behavior. In this article, we first present a novel approach to generate an ensemble of conformations and an efficient computational method to extract direct couplings of side chains in allosteric proteins, and provide sparse network representations of the couplings. We take the side-chain conformational polymorphism into account, and show that by studying the intrinsic dynamics of an inactive structure, we are able to construct a network of functionally crucial residues. Second, we show that the proposed method is capable of providing a magnified view of the coupled and conformationally polymorphic residues. This model reveals couplings between the alternate conformations of a coupled residue pair. To the best of our knowledge, this is the first computational method for extracting networks of side chains' alternate conformations. Such networks help in providing a detailed image of side-chain dynamics in functionally important and conformationally polymorphic sites, such as binding and/or allosteric sites. © 2014 Wiley Periodicals, Inc.

Individual versus Interactive Task-Based Performance through Voice-Based Computer-Mediated Communication

Science.gov (United States)

Granena, Gisela

2016-01-01

Interaction is a necessary condition for second language (L2) learning (Long, 1980, 1996). Research in computer-mediated communication has shown that interaction opportunities make learners pay attention to form in a variety of ways that promote L2 learning. This research has mostly investigated text-based rather than voice-based interaction. The…

Learners' Use of Communication Strategies in Text-Based and Video-Based Synchronous Computer-Mediated Communication Environments: Opportunities for Language Learning

Science.gov (United States)

Hung, Yu-Wan; Higgins, Steve

2016-01-01

This study investigates the different learning opportunities enabled by text-based and video-based synchronous computer-mediated communication (SCMC) from an interactionist perspective. Six Chinese-speaking learners of English and six English-speaking learners of Chinese were paired up as tandem (reciprocal) learning dyads. Each dyad participated…

Sniffer patch laser uncaging response (SPLURgE): an assay of regional differences in allosteric receptor modulation and neurotransmitter clearance.

Science.gov (United States)

Christian, Catherine A; Huguenard, John R

2013-10-01

Allosteric modulators exert actions on neurotransmitter receptors by positively or negatively altering the effective response of these receptors to their respective neurotransmitter. γ-Aminobutyric acid (GABA) type A ionotropic receptors (GABAARs) are major targets for allosteric modulators such as benzodiazepines, neurosteroids, and barbiturates. Analysis of substances that produce similar effects has been hampered by the lack of techniques to assess the localization and function of such agents in brain slices. Here we describe measurement of the sniffer patch laser uncaging response (SPLURgE), which combines the sniffer patch recording configuration with laser photolysis of caged GABA. This methodology enables the detection of allosteric GABAAR modulators endogenously present in discrete areas of the brain slice and allows for the application of exogenous GABA with spatiotemporal control without altering the release and localization of endogenous modulators within the slice. Here we demonstrate the development and use of this technique for the measurement of allosteric modulation in different areas of the thalamus. Application of this technique will be useful in determining whether a lack of modulatory effect on a particular category of neurons or receptors is due to insensitivity to allosteric modulation or a lack of local release of endogenous ligand. We also demonstrate that this technique can be used to investigate GABA diffusion and uptake. This method thus provides a biosensor assay for rapid detection of endogenous GABAAR modulators and has the potential to aid studies of allosteric modulators that exert effects on other classes of neurotransmitter receptors, such as glutamate, acetylcholine, or glycine receptors.

Social influence in computer-mediated communication : The effects of anonymity on group behavior

NARCIS (Netherlands)

Postmes, T; Spears, R; Sakhel, K; de Groot, D

2001-01-01

Two studies examined hypotheses derived from a Social Identity model of Deindividuation Effects (SIDE) as applied to social influence in computer-mediated communication (CMC) in groups. This model predicts that anonymity can increase social influence if a common group identity is salient. In a first

Adult attachment and male aggression in couple relationships: the demand-withdraw communication pattern and relationship satisfaction as mediators.

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Fournier, Benoit; Brassard, Audrey; Shaver, Phillip R

2011-07-01

This study examines men's domestic aggression as a function of attachment insecurities, considering the mediating roles of the demand-withdraw communication pattern and relationship satisfaction. The sample included 55 Canadian men undergoing counseling for relationship difficulties including aggression. The men completed questionnaires assessing physical and psychological aggression, the two dimensions of attachment insecurity (anxiety over abandonment and avoidance of intimacy), the demand-withdraw communication pattern, relationship satisfaction, and social desirability (a control measure). As predicted, there was an association between attachment anxiety and aggression (both physical and psychological), which was mediated by the man demands/woman withdraws (MD/WW) pattern (as reported by the men). There was no evidence of mediation by the woman demands/man withdraws pattern, as reported by the men. Relationship satisfaction mediated the association between attachment anxiety and psychological (but not physical) aggression, but did not mediate the link between avoidance and aggression (physical or psychological). Limitations and clinical implications are discussed.

The structure of brain glycogen phosphorylase-from allosteric regulation mechanisms to clinical perspectives.

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Mathieu, Cécile; Dupret, Jean-Marie; Rodrigues Lima, Fernando

2017-02-01

Glycogen phosphorylase (GP) is the key enzyme that regulates glycogen mobilization in cells. GP is a complex allosteric enzyme that comprises a family of three isozymes: muscle GP (mGP), liver GP (lGP), and brain GP (bGP). Although the three isozymes display high similarity and catalyze the same reaction, they differ in their sensitivity to the allosteric activator adenosine monophosphate (AMP). Moreover, inactivating mutations in mGP and lGP have been known to be associated with glycogen storage diseases (McArdle and Hers disease, respectively). The determination, decades ago, of the structure of mGP and lGP have allowed to better understand the allosteric regulation of these two isoforms and the development of specific inhibitors. Despite its important role in brain glycogen metabolism, the structure of the brain GP had remained elusive. Here, we provide an overview of the human brain GP structure and its relationship with the two other members of this key family of the metabolic enzymes. We also summarize how this structure provides valuable information to understand the regulation of bGP and to design specific ligands of potential pharmacological interest. © 2016 Federation of European Biochemical Societies.

Allosteric modulation of Ras and the PI3K/AKT/mTOR pathway: emerging therapeutic opportunities

Science.gov (United States)

Hubbard, Paul A.; Moody, Colleen L.; Murali, Ramachandran

2014-01-01

GTPases and kinases are two predominant signaling modules that regulate cell fate. Dysregulation of Ras, a GTPase, and the three eponymous kinases that form key nodes of the associated phosphatidylinositol 4,5-bisphosphate 3-kinase (PI3K)/AKT/mTOR pathway have been implicated in many cancers, including pancreatic cancer, a disease noted for its current lack of effective therapeutics. The K-Ras isoform of Ras is mutated in over 90% of pancreatic ductal adenocarcinomas (PDAC) and there is growing evidence linking aberrant PI3K/AKT/mTOR pathway activity to PDAC. Although these observations suggest that targeting one of these nodes might lead to more effective treatment options for patients with pancreatic and other cancers, the complex regulatory mechanisms and the number of sequence-conserved isoforms of these proteins have been viewed as significant barriers in drug development. Emerging insights into the allosteric regulatory mechanisms of these proteins suggest novel opportunities for development of selective allosteric inhibitors with fragment-based drug discovery (FBDD) helping make significant inroads. The fact that allosteric inhibitors of Ras and AKT are currently in pre-clinical development lends support to this approach. In this article, we will focus on the recent advances and merits of developing allosteric drugs targeting these two inter-related signaling pathways. PMID:25566081

Surface dynamics in allosteric regulation of protein-protein interactions: modulation of calmodulin functions by Ca2+.

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Yosef Y Kuttner

2013-04-01

Full Text Available Knowledge of the structural basis of protein-protein interactions (PPI is of fundamental importance for understanding the organization and functioning of biological networks and advancing the design of therapeutics which target PPI. Allosteric modulators play an important role in regulating such interactions by binding at site(s orthogonal to the complex interface and altering the protein's propensity for complex formation. In this work, we apply an approach recently developed by us for analyzing protein surfaces based on steered molecular dynamics simulation (SMD to the study of the dynamic properties of functionally distinct conformations of a model protein, calmodulin (CaM, whose ability to interact with target proteins is regulated by the presence of the allosteric modulator Ca(2+. Calmodulin is a regulatory protein that acts as an intracellular Ca(2+ sensor to control a wide variety of cellular processes. We demonstrate that SMD analysis is capable of pinpointing CaM surfaces implicated in the recognition of both the allosteric modulator Ca(2+ and target proteins. Our analysis of changes in the dynamic properties of the CaM backbone elicited by Ca(2+ binding yielded new insights into the molecular mechanism of allosteric regulation of CaM-target interactions.

A Systematic Review of Fidelity of Implementation in Parent-Mediated Early Communication Intervention

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Lieberman-Betz, Rebecca G.

2015-01-01

This article examined the reporting of four elements of fidelity of implementation (FOI) in parent-mediated early communication treatment studies. Thirty-five studies were reviewed to extract information regarding reporting of dosage, adherence, quality, and participant responsiveness for both practitioners and parents involved in parent-delivered…

Supramolecular Allosteric Cofacial Porphyrin Complexes

International Nuclear Information System (INIS)

Oliveri, Christopher G.; Gianneschi, Nathan C.; Nguyen, Son Binh T.; Mirkin, Chad A.; Stern, Charlotte L.; Wawrzak, Zdzislaw; Pink, Maren

2008-01-01

Nature routinely uses cooperative interactions to regulate cellular activity. For years, chemists have designed synthetic systems that aim toward harnessing the reactivity common to natural biological systems. By learning how to control these interactions in situ, one begins to allow for the preparation of man-made biomimetic systems that can efficiently mimic the interactions found in Nature. To this end, we have designed a synthetic protocol for the preparation of flexible metal-directed supramolecular cofacial porphyrin complexes which are readily obtained in greater than 90% yield through the use of new hemilabile porphyrin ligands with bifunctional ether-phosphine or thioether-phosphine substituents at the 5 and 15 positions on the porphyrin ring. The resulting architectures contain two hemilabile ligand-metal domains (Rh I or Cu I sites) and two cofacially aligned porphyrins (Zn II sites), offering orthogonal functionalities and allowing these multimetallic complexes to exist in two states, 'condensed' or 'open'. Combining the ether-phosphine ligand with the appropriate Rh I or Cu I transition-metal precursors results in 'open' macrocyclic products. In contrast, reacting the thioether-phosphine ligand with RhI or CuI precursors yields condensed structures that can be converted into their 'open' macrocyclic forms via introduction of additional ancillary ligands. The change in cavity size that occurs allows these structures to function as allosteric catalysts for the acyl transfer reaction between X-pyridylcarbinol (where X = 2, 3, or 4) and 1-acetylimidazole. For 3- and 4-pyridylcarbinol, the 'open' macrocycle accelerates the acyl transfer reaction more than the condensed analogue and significantly more than the porphyrin monomer. In contrast, an allosteric effect was not observed for 2-pyridylcarbinol, which is expected to be a weaker binder and is unfavorably constrained inside the macrocyclic cavity.

Implementation of communication-mediating domains for non-ribosomal peptide production in Saccharomyces cerevisiae

DEFF Research Database (Denmark)

Siewers, Verena; San-Bento, Rita; Nielsen, Jens

2010-01-01

Saccharomyces cerevisiae has in several cases been proven to be a suitable host for the production of natural products and was recently exploited for the production of non-ribosomal peptides. Synthesis of non-ribosomal peptides (NRPs) is mediated by NRP synthetases (NRPSs), modular enzymes, which...... are often organized in enzyme complexes. In these complexes, partner NRPSs interact via communication-mediating domains (COM domains). In order to test whether functional interaction between separate NRPS modules is possible in yeast we constructed a yeast strain expressing two modules with compatible COM...

Activation of Hsp90 Enzymatic Activity and Conformational Dynamics through Rationally Designed Allosteric Ligands.

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Sattin, Sara; Tao, Jiahui; Vettoretti, Gerolamo; Moroni, Elisabetta; Pennati, Marzia; Lopergolo, Alessia; Morelli, Laura; Bugatti, Antonella; Zuehlke, Abbey; Moses, Mike; Prince, Thomas; Kijima, Toshiki; Beebe, Kristin; Rusnati, Marco; Neckers, Len; Zaffaroni, Nadia; Agard, David A; Bernardi, Anna; Colombo, Giorgio

2015-09-21

Hsp90 is a molecular chaperone of pivotal importance for multiple cell pathways. ATP-regulated internal dynamics are critical for its function and current pharmacological approaches block the chaperone with ATP-competitive inhibitors. Herein, a general approach to perturb Hsp90 through design of new allosteric ligands aimed at modulating its functional dynamics is proposed. Based on the characterization of a first set of 2-phenylbenzofurans showing stimulatory effects on Hsp90 ATPase and conformational dynamics, new ligands were developed that activate Hsp90 by targeting an allosteric site, located 65 Å from the active site. Specifically, analysis of protein responses to first-generation activators was exploited to guide the design of novel derivatives with improved ability to stimulate ATP hydrolysis. The molecules' effects on Hsp90 enzymatic, conformational, co-chaperone and client-binding properties were characterized through biochemical, biophysical and cellular approaches. These designed probes act as allosteric activators of the chaperone and affect the viability of cancer cell lines for which proper functioning of Hsp90 is necessary. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Allosteric Mutant IDH1 Inhibitors Reveal Mechanisms for IDH1 Mutant and Isoform Selectivity

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Xie, Xiaoling; Baird, Daniel; Bowen, Kimberly; Capka, Vladimir; Chen, Jinyun; Chenail, Gregg; Cho, YoungShin; Dooley, Julia; Farsidjani, Ali; Fortin, Pascal; Kohls, Darcy; Kulathila, Raviraj; Lin, Fallon; McKay, Daniel; Rodrigues, Lindsey; Sage, David; Touré, B. Barry; van der Plas, Simon; Wright, Kirk; Xu, Ming; Yin, Hong; Levell, Julian; Pagliarini, Raymond A. (Novartis)

2017-03-01

Oncogenic IDH1 and IDH2 mutations contribute to cancer via production of R-2-hydroxyglutarate (2-HG). Here, we characterize two structurally distinct mutant- and isoform-selective IDH1 inhibitors that inhibit 2-HG production. Both bind to an allosteric pocket on IDH1, yet shape it differently, highlighting the plasticity of this site. Oncogenic IDH1R132H mutation destabilizes an IDH1 “regulatory segment,” which otherwise restricts compound access to the allosteric pocket. Regulatory segment destabilization in wild-type IDH1 promotes inhibitor binding, suggesting that destabilization is critical for mutant selectivity. We also report crystal structures of oncogenic IDH2 mutant isoforms, highlighting the fact that the analogous segment of IDH2 is not similarly destabilized. This intrinsic stability of IDH2 may contribute to observed inhibitor IDH1 isoform selectivity. Moreover, discrete residues in the IDH1 allosteric pocket that differ from IDH2 may also guide IDH1 isoform selectivity. These data provide a deeper understanding of how IDH1 inhibitors achieve mutant and isoform selectivity.

Zinc-mediated Allosteric Inhibition of Caspase-6*

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Velázquez-Delgado, Elih M.; Hardy, Jeanne A.

2012-01-01

Zinc and caspase-6 have independently been implicated in several neurodegenerative disorders. Depletion of zinc intracellularly leads to apoptosis by an unknown mechanism. Zinc inhibits cysteine proteases, including the apoptotic caspases, leading to the hypothesis that zinc-mediated inhibition of caspase-6 might contribute to its regulation in a neurodegenerative context. Using inductively coupled plasma optical emission spectroscopy, we observed that caspase-6 binds one zinc per monomer, under the same conditions where the zinc leads to complete loss of enzymatic activity. To understand the molecular details of zinc binding and inhibition, we performed an anomalous diffraction experiment above the zinc edge. The anomalous difference maps showed strong 5σ peaks, indicating the presence of one zinc/monomer bound at an exosite distal from the active site. Zinc was not observed bound to the active site. The zinc in the exosite was liganded by Lys-36, Glu-244, and His-287 with a water molecule serving as the fourth ligand, forming a distorted tetrahedral ligation sphere. This exosite appears to be unique to caspase-6, as the residues involved in zinc binding were not conserved across the caspase family. Our data suggest that binding of zinc at the exosite is the primary route of inhibition, potentially locking caspase-6 into the inactive helical conformation. PMID:22891250

Picture Exchange Communication System and Pals: A Peer-Mediated Augmentative and Alternative Communication Intervention for Minimally Verbal Preschoolers with Autism

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Thiemann-Bourque, Kathy; Brady, Nancy; McGuff, Sara; Strump, Keenan; Naylor, Amy

2016-01-01

Purpose: This study was conducted to investigate the effectiveness of a social intervention that integrates peer-mediated approaches and the Picture Exchange Communication System (PECS). Method: Effects were evaluated using a series of A-B designs replicated across 4 children with severe autism and limited verbal skills. Seven peers without…

Computer-Mediated Communication as an Autonomy-Enhancement Tool for Advanced Learners of English

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Wach, Aleksandra

2012-01-01

This article examines the relevance of modern technology for the development of learner autonomy in the process of learning English as a foreign language. Computer-assisted language learning and computer-mediated communication (CMC) appear to be particularly conducive to fostering autonomous learning, as they naturally incorporate many elements of…

The Role of Protein-Ligand Contacts in Allosteric Regulation of the Escherichia coli Catabolite Activator Protein*

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Townsend, Philip D.; Rodgers, Thomas L.; Glover, Laura C.; Korhonen, Heidi J.; Richards, Shane A.; Colwell, Lucy J.; Pohl, Ehmke; Wilson, Mark R.; Hodgson, David R. W.; McLeish, Tom C. B.; Cann, Martin J.

2015-01-01

Allostery is a fundamental process by which ligand binding to a protein alters its activity at a distant site. Both experimental and theoretical evidence demonstrate that allostery can be communicated through altered slow relaxation protein dynamics without conformational change. The catabolite activator protein (CAP) of Escherichia coli is an exemplar for the analysis of such entropically driven allostery. Negative allostery in CAP occurs between identical cAMP binding sites. Changes to the cAMP-binding pocket can therefore impact the allosteric properties of CAP. Here we demonstrate, through a combination of coarse-grained modeling, isothermal calorimetry, and structural analysis, that decreasing the affinity of CAP for cAMP enhances negative cooperativity through an entropic penalty for ligand binding. The use of variant cAMP ligands indicates the data are not explained by structural heterogeneity between protein mutants. We observe computationally that altered interaction strength between CAP and cAMP variously modifies the change in allosteric cooperativity due to second site CAP mutations. As the degree of correlated motion between the cAMP-contacting site and a second site on CAP increases, there is a tendency for computed double mutations at these sites to drive CAP toward noncooperativity. Naturally occurring pairs of covarying residues in CAP do not display this tendency, suggesting a selection pressure to fine tune allostery on changes to the CAP ligand-binding pocket without a drive to a noncooperative state. In general, we hypothesize an evolutionary selection pressure to retain slow relaxation dynamics-induced allostery in proteins in which evolution of the ligand-binding site is occurring. PMID:26187469

A mechanistic understanding of allosteric immune escape pathways in the HIV-1 envelope glycoprotein.

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Anurag Sethi

Full Text Available The HIV-1 envelope (Env spike, which consists of a compact, heterodimeric trimer of the glycoproteins gp120 and gp41, is the target of neutralizing antibodies. However, the high mutation rate of HIV-1 and plasticity of Env facilitates viral evasion from neutralizing antibodies through various mechanisms. Mutations that are distant from the antibody binding site can lead to escape, probably by changing the conformation or dynamics of Env; however, these changes are difficult to identify and define mechanistically. Here we describe a network analysis-based approach to identify potential allosteric immune evasion mechanisms using three known HIV-1 Env gp120 protein structures from two different clades, B and C. First, correlation and principal component analyses of molecular dynamics (MD simulations identified a high degree of long-distance coupled motions that exist between functionally distant regions within the intrinsic dynamics of the gp120 core, supporting the presence of long-distance communication in the protein. Then, by integrating MD simulations with network theory, we identified the optimal and suboptimal communication pathways and modules within the gp120 core. The results unveil both strain-dependent and -independent characteristics of the communication pathways in gp120. We show that within the context of three structurally homologous gp120 cores, the optimal pathway for communication is sequence sensitive, i.e. a suboptimal pathway in one strain becomes the optimal pathway in another strain. Yet the identification of conserved elements within these communication pathways, termed inter-modular hotspots, could present a new opportunity for immunogen design, as this could be an additional mechanism that HIV-1 uses to shield vulnerable antibody targets in Env that induce neutralizing antibody breadth.

Mutations that silence constitutive signaling activity in the allosteric ligand-binding site of the thyrotropin receptor.

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Haas, Ann-Karin; Kleinau, Gunnar; Hoyer, Inna; Neumann, Susanne; Furkert, Jens; Rutz, Claudia; Schülein, Ralf; Gershengorn, Marvin C; Krause, Gerd

2011-01-01

The thyrotropin receptor (TSHR) exhibits elevated cAMP signaling in the basal state and becomes fully activated by thyrotropin. Previously we presented evidence that small-molecule ligands act allosterically within the transmembrane region in contrast to the orthosteric extracellular hormone-binding sites. Our goal in this study was to identify positions that surround the allosteric pocket and that are sensitive for inactivation of TSHR. Homology modeling combined with site-directed mutagenesis and functional characterization revealed seven mutants located in the allosteric binding site that led to a decrease of basal cAMP signaling activity. The majority of these silencing mutations, which constrain the TSHR in an inactive conformation, are found in two clusters when mapped onto the 3D structural model. We suggest that the amino acid positions identified herein are indicating locations where small-molecule antagonists, both neutral antagonists and inverse agonists, might interfere with active TSHR conformations.

Computer-mediated and face-to-face communication in metastatic cancer support groups.

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Vilhauer, Ruvanee P

2014-08-01

To compare the experiences of women with metastatic breast cancer (MBC) in computer-mediated and face-to-face support groups. Interviews from 18 women with MBC, who were currently in computer-mediated support groups (CMSGs), were examined using interpretative phenomenological analysis. The CMSGs were in an asynchronous mailing list format; women communicated exclusively via email. All the women were also, or had previously been, in a face-to-face support group (FTFG). CMSGs had both advantages and drawbacks, relative to face-to-face groups (FTFGs), for this population. Themes examined included convenience, level of support, intimacy, ease of expression, range of information, and dealing with debilitation and dying. CMSGs may provide a sense of control and a greater level of support. Intimacy may take longer to develop in a CMSG, but women may have more opportunities to get to know each other. CMSGs may be helpful while adjusting to a diagnosis of MBC, because women can receive support without being overwhelmed by physical evidence of disability in others or exposure to discussions about dying before they are ready. However, the absence of nonverbal cues in CMSGs also led to avoidance of topics related to death and dying when women were ready to face them. Agendas for discussion, the presence of a facilitator or more time in CMSGs may attenuate this problem. The findings were discussed in light of prevailing research and theories about computer-mediated communication. They have implications for designing CMSGs for this population.

Computer-mediated communication in adults with high-functioning autism spectrum disorders and controls

NARCIS (Netherlands)

van der Aa, Christine; Pollmann, Monique; Plaat, Aske; van der Gaag, Rutger Jan

2016-01-01

It has been suggested that people with Autism Spectrum Disorders (ASD) are attracted to computer-mediated communication (CMC). In this study, we compare CMC use in adults with high-functioning ASD (N = 113) and a control group (N = 72). We find that people with ASD spend more time on CMC than

Can Synchronous Computer-Mediated Communication (CMC) Help Beginning-Level Foreign Language Learners Speak?

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Ko, Chao-Jung

2012-01-01

This study investigated the possibility that initial-level learners may acquire oral skills through synchronous computer-mediated communication (SCMC). Twelve Taiwanese French as a foreign language (FFL) students, divided into three groups, were required to conduct a variety of tasks in one of the three learning environments (video/audio, audio,…

Cross-Cultural Communication Patterns in Computer Mediated Communication

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Panina, Daria; Kroumova, Maya

2015-01-01

There are important cultural differences in attitudes towards and use of electronic text communication. Consistent with Hall's high-context/low-context conceptualization of culture, electronic inter-cultural communication, just as verbal inter-cultural communication, is affected by the culturally-specific assumptions and preferences of message…

Conserved allosteric hot spots in the transmembrane domains of cystic fibrosis transmembrane conductance regulator (CFTR) channels and multidrug resistance protein (MRP) pumps.

Science.gov (United States)

Wei, Shipeng; Roessler, Bryan C; Chauvet, Sylvain; Guo, Jingyu; Hartman, John L; Kirk, Kevin L

2014-07-18

ATP-binding cassette (ABC) transporters are an ancient family of transmembrane proteins that utilize ATPase activity to move substrates across cell membranes. The ABCC subfamily of the ABC transporters includes active drug exporters (the multidrug resistance proteins (MRPs)) and a unique ATP-gated ion channel (cystic fibrosis transmembrane conductance regulator (CFTR)). The CFTR channel shares gating principles with conventional ligand-gated ion channels, but the allosteric network that couples ATP binding at its nucleotide binding domains (NBDs) with conformational changes in its transmembrane helices (TMs) is poorly defined. It is also unclear whether the mechanisms that govern CFTR gating are conserved with the thermodynamically distinct MRPs. Here we report a new class of gain of function (GOF) mutation of a conserved proline at the base of the pore-lining TM6. Multiple substitutions of this proline promoted ATP-free CFTR activity and activation by the weak agonist, 5'-adenylyl-β,γ-imidodiphosphate (AMP-PNP). TM6 proline mutations exhibited additive GOF effects when combined with a previously reported GOF mutation located in an outer collar of TMs that surrounds the pore-lining TMs. Each TM substitution allosterically rescued the ATP sensitivity of CFTR gating when introduced into an NBD mutant with defective ATP binding. Both classes of GOF mutations also rescued defective drug export by a yeast MRP (Yor1p) with ATP binding defects in its NBDs. We conclude that the conserved TM6 proline helps set the energy barrier to both CFTR channel opening and MRP-mediated drug efflux and that CFTR channels and MRP pumps utilize similar allosteric mechanisms for coupling conformational changes in their translocation pathways to ATP binding at their NBDs. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Allosteric mechanisms within the adenosine A2A-dopamine D2 receptor heterotetramer

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Ferré, Sergi; Bonaventura, Jordi; Tomasi, Dardo; Navarro, Gemma; Moreno, Estefanía; Cortés, Antonio; Lluís, Carme; Casadó, Vicent; Volkow, Nora D.

2017-01-01

The structure constituted by a G protein coupled receptor (GPCR) homodimer and a G protein provides a main functional unit and oligomeric entities can be viewed as multiples of dimers. For GPCR heteromers, experimental evidence supports a tetrameric structure, comprised of two different homodimers, each able to signal with its preferred G protein. GPCR homomers and heteromers can act as the conduit of allosteric interactions between orthosteric ligands. The well-known agonist/agonist allosteric interaction in the adenosine A2A receptor (A2AR)-dopamine D2 receptor (D2R) heteromer, by which A2AR agonists decrease the affinity of D2R agonists, gave the first rationale for the use of A2AR antagonists in Parkinson’s disease. We review new pharmacological findings that can be explained in the frame of a tetrameric structure of the A2AR-D2R heteromer: first, ligand-independent allosteric modulations by the D2R that result in changes of the binding properties of A2AR ligands; second, differential modulation of the intrinsic efficacy of D2R ligands for G protein-dependent and independent signaling; third, the canonical antagonistic Gs-Gi interaction within the frame of the heteromer; and fourth, the ability of A2AR antagonists, including caffeine, to also exert the same allosteric modulations of D2R ligands than A2AR agonists, while A2AR agonists and antagonists counteract each other’s effects. These findings can have important clinical implications when evaluating the use of A2AR antagonists. They also call for the need of monitoring caffeine intake when evaluating the effect of D2R ligands, when used as therapeutic agents in neuropsychiatric disorders or as probes in imaging studies. PMID:26051403

Confidence in communicating with patients with cancer mediates the relationship between rehabilitation therapists' autistic-like traits and perceived difficulty in communication.

Science.gov (United States)

Hayashibara, Chinatsu; Inagaki, Masatoshi; Fujimori, Maiko; Higuchi, Yuji; Fujiwara, Masaki; Terada, Seishi; Okamura, Hitoshi; Uchitomi, Yosuke; Yamada, Norihito

2018-01-21

Recently, rehabilitation therapists have become involved in cancer rehabilitation; however, no communication skills training that increases the ability to provide emotional support for cancer patients has been developed for rehabilitation therapists. In addition, no study has examined associations between rehabilitation therapists' communication skills and their level of autistic-like traits (ALT), which are in-born characteristics including specific communication styles and difficulty communicating with patients. In this study, we aimed to investigate whether confidence in communicating with patients mitigates communication difficulties experienced by rehabilitation therapists who have high levels of ALT. Rehabilitation therapists who treat patients with cancer completed self-administered postal questionnaires anonymously. Scores were obtained on the Autism-Spectrum Quotient short form, confidence in communication, and communication difficulties. We used covariance structure analyses to test hypothetical models, and confirmed that confidence in communication mediates the relationship between ALT and perceived communication difficulties. Participants included 1,343 respondents (49.6%). Autism-Spectrum Quotient scores were positively correlated with communication difficulties (r = 0.16, p confidence in communication in the fit model. However, higher confidence in creating a supportive atmosphere was associated with more difficulty in communication (r = 0.16, p Communication difficulty was linked to rehabilitation therapists' ALTs. By increasing confidence in areas of communication other than creation of a supportive atmosphere, ALT-related difficulties in communication may be ameliorated. Confidence to create supportive environments correlated positively with difficulty. Communication skills training to increase confidence in communication for rehabilitation therapists should be developed with vigilance regarding ALT levels.

First steps in the direction of synthetic, allosteric, direct inhibitors of thrombin and factor Xa.

Science.gov (United States)

Verghese, Jenson; Liang, Aiye; Sidhu, Preet Pal Singh; Hindle, Michael; Zhou, Qibing; Desai, Umesh R

2009-08-01

Designing non-saccharide functional mimics of heparin is a major challenge. In this work, a library of small, aromatic molecules based on the sulfated DHP scaffold was synthesized and screened against thrombin and factor Xa. The results reveal that (i) selected monomeric benzofuran derivatives inhibit the two enzymes, albeit weakly; (ii) the two enzymes recognize different structural features in the benzofurans studied suggesting significant selectivity of recognition; and (iii) the mechanism of inhibition is allosteric. The molecules represent the first allosteric small molecule inhibitors of the two enzymes.

First Steps in the Direction of Synthetic, Allosteric, Direct Inhibitors of Thrombin and Factor Xa

Science.gov (United States)

Verghese, Jenson; Liang, Aiye; Sidhu, Preet Pal Singh; Hindle, Michael; Zhou, Qibing; Desai, Umesh R.

2009-01-01

Designing non-saccharide functional mimics of heparin is a major challenge. In this work, a library of small, aromatic molecules based on the sulfated DHP scaffold was synthesized and screened against thrombin and factor Xa. The results reveal that i) selected monomeric benzofuran derivatives inhibit the two enzymes, albeit weakly; ii) the two enzymes recognize different structural features in the benzofurans studied suggesting significant selectivity of recognition; and iii) the mechanism of inhibition is allosteric. The molecules represent the first allosteric small molecule inhibitors of the two enzymes. PMID:19540113

Identification of an allosteric binding site for RORγt inhibition

NARCIS (Netherlands)

Scheepstra, M.; Leysen, S.; van Almen, G.; Miller, J.R.; Piesvaux, J.; Kutilek, V.; van Eenennaam, H.; Zhang, H.; Barr, K.; Nagpal, S.; Soisson, S.M.; Kornienko, M.; Wiley, K.; Elsen, N.; Sharma, S.; Correll, C.C.; Trotter, B.W.; Stelt, van der M.; Oubrie, A.; Ottmann, C.; Parthasarathy, G.; Brunsveld, L.

2015-01-01

RORγt is critical for the differentiation and proliferation of Th17 cells associated with several chronic autoimmune diseases. We report the discovery of a novel allosteric binding site on the nuclear receptor RORγt. Co-crystallization of the ligand binding domain (LBD) of RORγt with a series of

Meaning Making Through Minimal Linguistic Forms in Computer-Mediated Communication

Directory of Open Access Journals (Sweden)

Muhammad Shaban Rafi

2014-05-01

Full Text Available The purpose of this study was to investigate the linguistic forms, which commonly constitute meanings in the digital environment. The data were sampled from 200 Bachelor of Science (BS students (who had Urdu as their primary language of communication and English as one of the academic languages or the most prestigious second language of five universities situated in Lahore, Pakistan. The procedure for analysis was conceived within much related theoretical work on text analysis. The study reveals that cyber-language is organized through patterns of use, which can be broadly classified into minimal linguistic forms constituting a meaning-making resource. In addition, the expression of syntactic mood, and discourse roles the participants technically assume tend to contribute to the theory of meaning in the digital environment. It is hoped that the study would make some contribution to the growing literature on multilingual computer-mediated communication (CMC.

Staying Connected: Computer-Mediated and Face-to-Face Communication in College Students' Dating Relationships.

Science.gov (United States)

Boyle, Andrea M; O'Sullivan, Lucia F

2016-05-01

Little is known about the features, depth, and quality of communication in heterosexual dating relationships that include computer-mediated communication (CMC). This study examined these features as well as CMC's potential to facilitate self-disclosure and information-seeking. It also evaluated whether partner CMC interactions play a role in partner intimacy and communication quality. Young adults (N = 359; 18-24) attending postsecondary education institutions completed an online survey about their CMC use. To be included in the study, all participants were in established dating relationships at the time of the study and reported daily communication with their partner. CMC was linked to partners' disclosure of nonintimate information. This personal self-disclosure was linked positively to relationship intimacy and communication quality, beyond contributions from face-to-face interactions. Breadth (not depth) of self-disclosure and positively valenced interactions, in particular, proved key to understanding greater levels of intimacy in dating relationships and better communication quality as a function of CMC. CMC provides opportunities for partners to stay connected and to improve the overall quality of their intimacy and communication.

Structural Bioinformatics and Protein Docking Analysis of the Molecular Chaperone-Kinase Interactions: Towards Allosteric Inhibition of Protein Kinases by Targeting the Hsp90-Cdc37 Chaperone Machinery

Directory of Open Access Journals (Sweden)

Gennady Verkhivker

2013-11-01

Full Text Available A fundamental role of the Hsp90-Cdc37 chaperone system in mediating maturation of protein kinase clients and supporting kinase functional activity is essential for the integrity and viability of signaling pathways involved in cell cycle control and organism development. Despite significant advances in understanding structure and function of molecular chaperones, the molecular mechanisms and guiding principles of kinase recruitment to the chaperone system are lacking quantitative characterization. Structural and thermodynamic characterization of Hsp90-Cdc37 binding with protein kinase clients by modern experimental techniques is highly challenging, owing to a transient nature of chaperone-mediated interactions. In this work, we used experimentally-guided protein docking to probe the allosteric nature of the Hsp90-Cdc37 binding with the cyclin-dependent kinase 4 (Cdk4 kinase clients. The results of docking simulations suggest that the kinase recognition and recruitment to the chaperone system may be primarily determined by Cdc37 targeting of the N-terminal kinase lobe. The interactions of Hsp90 with the C-terminal kinase lobe may provide additional “molecular brakes” that can lock (or unlock kinase from the system during client loading (release stages. The results of this study support a central role of the Cdc37 chaperone in recognition and recruitment of the kinase clients. Structural analysis may have useful implications in developing strategies for allosteric inhibition of protein kinases by targeting the Hsp90-Cdc37 chaperone machinery.

Structural and kinetic studies of the allosteric transition in Sulfolobus solfataricus uracil phosphoribosyltransferase: Permanent activation by engineering of the C-terminus

DEFF Research Database (Denmark)

Christoffersen, Stig; Kadziola, Anders; Johansson, Eva

2009-01-01

and PPi, in the other sites. Combined with three existing structures of uracil phosphoribosyltransferase in complex with UMP and the allosteric inhibitor cytidine triphosphate (CTP), these structures provide valuable insight into the mechanism of allosteric transition from inhibited to active enzyme...

Computer-mediated communication as a channel for social resistance : The strategic side of SIDE

NARCIS (Netherlands)

Spears, R; Lea, M; Corneliussen, RA; Postmes, T; Ter Haar, W

2002-01-01

In two studies, the authors tested predictions derived from the social identity model of deindividuation effects (SIDE) concerning the potential of computer-mediated communication (CMC) to serve as a means to resist powerful out-groups. Earlier research using the SIDE model indicates that the

Allosteric inhibitors of Coxsackie virus A24 RNA polymerase.

Science.gov (United States)

Schein, Catherine H; Rowold, Diane; Choi, Kyung H

2016-02-15

Coxsackie virus A24 (CVA24), a causative agent of acute hemorrhagic conjunctivitis, is a prototype of enterovirus (EV) species C. The RNA polymerase (3D(pol)) of CVA24 can uridylylate the viral peptide linked to the genome (VPg) from distantly related EV and is thus, a good model for studying this reaction. Once UMP is bound, VPgpU primes RNA elongation. Structural and mutation data have identified a conserved binding surface for VPg on the RNA polymerase (3D(pol)), located about 20Å from the active site. Here, computational docking of over 60,000 small compounds was used to select those with the lowest (best) specific binding energies (BE) for this allosteric site. Compounds with varying structures and low BE were assayed for their effect on formation of VPgU by CVA24-3D(pol). Two compounds with the lowest specific BE for the site inhibited both uridylylation and formation of VPgpolyU at 10-20μM. These small molecules can be used to probe the role of this allosteric site in polymerase function, and may be the basis for novel antiviral compounds. Copyright © 2015 Elsevier Ltd. All rights reserved.

Computer-Mediated Communication (CMC) in L2 Oral Proficiency Development: A Meta-Analysis

Science.gov (United States)

Lin, Huifen

2015-01-01

The ever growing interest in the development of foreign or second (L2) oral proficiency in a computer-mediated communication (CMC) classroom has resulted in a large body of studies looking at both the direct and indirect effects of CMC interventions on the acquisition of oral competences. The present study employed a quantitative meta-analytic…

Mutually Beneficial Foreign Language Learning: Creating Meaningful Interactions through Video-Synchronous Computer-Mediated Communication

Science.gov (United States)

Kato, Fumie; Spring, Ryan; Mori, Chikako

2016-01-01

Providing learners of a foreign language with meaningful opportunities for interactions, specifically with native speakers, is especially challenging for instructors. One way to overcome this obstacle is through video-synchronous computer-mediated communication tools such as Skype software. This study reports quantitative and qualitative data from…

Long Distance Modulation of Disorder-to-Order Transitions in Protein Allostery.

Science.gov (United States)

Wang, Jingheng; Custer, Gregory; Beckett, Dorothy; Matysiak, Silvina

2017-08-29

Elucidation of the molecular details of allosteric communication between distant sites in a protein is key to understanding and manipulating many biological regulatory processes. Although protein disorder is acknowledged to play an important thermodynamic role in allostery, the molecular mechanisms by which this disorder is harnessed for long distance communication are known for a limited number of systems. Transcription repression by the Escherichia coli biotin repressor, BirA, is allosterically activated by binding of the small molecule effector biotinoyl-5'-AMP. The effector acts by promoting BirA dimerization, which is a prerequisite for sequence-specific binding to the biotin biosynthetic operon operator sequence. A 30 Å distance separates the effector binding and dimerization surfaces in BirA, and previous studies indicate that allostery is mediated, in part, by disorder-to-order transitions on the two coupled sites. In this work, combined experimental and computational methods have been applied to investigate the molecular basis of allosteric communication in BirA. Double-mutant cycle analysis coupled with thermodynamic measurements indicates functional coupling between residues in disordered loops on the two distant surfaces. All atom molecular dynamics simulations reveal that this coupling occurs through long distance reciprocal modulation of the structure and dynamics of disorder-to-order transitions on the two surfaces.

Mediatization

DEFF Research Database (Denmark)

Hjarvard, Stig

2017-01-01

Mediatization research shares media effects studies' ambition of answering the difficult questions with regard to whether and how media matter and influence contemporary culture and society. The two approaches nevertheless differ fundamentally in that mediatization research seeks answers...... to these general questions by distinguishing between two concepts: mediation and mediatization. The media effects tradition generally considers the effects of the media to be a result of individuals being exposed to media content, i.e. effects are seen as an outcome of mediated communication. Mediatization...... research is concerned with long-term structural changes involving media, culture, and society, i.e. the influences of the media are understood in relation to how media are implicated in social and cultural changes and how these processes come to create new conditions for human communication and interaction...

Intracellular calcium levels determine differential modulation of allosteric interactions within G protein-coupled receptor heteromers.

Science.gov (United States)

Navarro, Gemma; Aguinaga, David; Moreno, Estefania; Hradsky, Johannes; Reddy, Pasham P; Cortés, Antoni; Mallol, Josefa; Casadó, Vicent; Mikhaylova, Marina; Kreutz, Michael R; Lluís, Carme; Canela, Enric I; McCormick, Peter J; Ferré, Sergi

2014-11-20

The pharmacological significance of the adenosine A2A receptor (A2AR)-dopamine D2 receptor (D2R) heteromer is well established and it is being considered as an important target for the treatment of Parkinson’s disease and other neuropsychiatric disorders. However, the physiological factors that control its distinctive biochemical properties are still unknown. We demonstrate that different intracellular Ca2+ levels exert a differential modulation of A2AR-D2R heteromer-mediated adenylyl-cyclase and MAPK signaling in striatal cells. This depends on the ability of low and high Ca2+ levels to promote a selective interaction of the heteromer with the neuronal Ca2+-binding proteins NCS-1 and calneuron-1, respectively. These Ca2+-binding proteins differentially modulate allosteric interactions within the A2AR-D2R heteromer, which constitutes a unique cellular device that integrates extracellular (adenosine and dopamine) and intracellular (Ca+2) signals to produce a specific functional response.

A2A adenosine receptor ligand binding and signalling is allosterically modulated by adenosine deaminase.

Science.gov (United States)

Gracia, Eduard; Pérez-Capote, Kamil; Moreno, Estefanía; Barkešová, Jana; Mallol, Josefa; Lluís, Carme; Franco, Rafael; Cortés, Antoni; Casadó, Vicent; Canela, Enric I

2011-05-01

A2ARs (adenosine A2A receptors) are highly enriched in the striatum, which is the main motor control CNS (central nervous system) area. BRET (bioluminescence resonance energy transfer) assays showed that A2AR homomers may act as cell-surface ADA (adenosine deaminase; EC 3.5.4.4)-binding proteins. ADA binding affected the quaternary structure of A2ARs present on the cell surface. ADA binding to adenosine A2ARs increased both agonist and antagonist affinity on ligand binding to striatal membranes where these proteins are co-expressed. ADA also increased receptor-mediated ERK1/2 (extracellular-signal-regulated kinase 1/2) phosphorylation. Collectively, the results of the present study show that ADA, apart from regulating the concentration of extracellular adenosine, may behave as an allosteric modulator that markedly enhances ligand affinity and receptor function. This powerful regulation may have implications for the physiology and pharmacology of neuronal A2ARs.

Contact-mediated and humoral communication between vascular endothelial and smooth muscle cells in vitro

International Nuclear Information System (INIS)

Davies, P.F.

1986-01-01

Vascular endothelial cells (EC) and smooth muscle cells (SMC) co-exist in close apposition to each other in all blood vessels except capillaries. Investigations of the metabolic interactions that may occur between these cells are essential to an understanding of vascular homeostasis and the pathogenesis of atherosclerosis. The authors have developed two in vitro models of co-temporal vascular cell communication. The first facilitates reversible microcarrier-mediated gap junctional communication between EC and SMC monolayers. When either EC or SMC were prelabelled with 3 H-uridine, intracellular nucleotide rapidly transferred across the region of heterocellular attachment to the complementary cell population. Cytoplasmic continuity between EC and SMC allowed metabolic cooperation via ions and small molecules (<1.5 KD). Thus, vascular reactivity, particularly in the microcirculation where myoendothelial gap junctions have been observed, may involve cytoplasmic second messengers transported from EC to SMC. In the second model, humoral communication was established between separated cultures of EC and SMC which shared the same culture medium. Endothelial-specific stimulation of SMC growth and lipoprotein metabolism via soluble factors was demonstrated. Two mechanisms of stimulation of SMC lipoprotein metabolism were identified; one endothelial derived mitogen-dependent, the other mitogen-independent which was mediated via low molecular weight endothelial cell products

Structural Insights into the Allosteric Operation of the Lon AAA+ Protease.

Science.gov (United States)

Lin, Chien-Chu; Su, Shih-Chieh; Su, Ming-Yuan; Liang, Pi-Hui; Feng, Chia-Cheng; Wu, Shih-Hsiung; Chang, Chung-I

2016-05-03

The Lon AAA+ protease (LonA) is an evolutionarily conserved protease that couples the ATPase cycle into motion to drive substrate translocation and degradation. A hallmark feature shared by AAA+ proteases is the stimulation of ATPase activity by substrates. Here we report the structure of LonA bound to three ADPs, revealing the first AAA+ protease assembly where the six protomers are arranged alternately in nucleotide-free and bound states. Nucleotide binding induces large coordinated movements of conserved pore loops from two pairs of three non-adjacent protomers and shuttling of the proteolytic groove between the ATPase site and a previously unknown Arg paddle. Structural and biochemical evidence supports the roles of the substrate-bound proteolytic groove in allosteric stimulation of ATPase activity and the conserved Arg paddle in driving substrate degradation. Altogether, this work provides a molecular framework for understanding how ATP-dependent chemomechanical movements drive allosteric processes for substrate degradation in a major protein-destruction machine. Copyright © 2016 Elsevier Ltd. All rights reserved.

Studies on allosteric phenomena in glycogen phosphorylase b.

Science.gov (United States)

Madsen, N B; Avramovic-Zikic, O; Lue, P F; Honikel, K O

1976-03-26

This article attempts to trace, from a personal point of view, the history of discoveries of allosteric phenomena in phosphorylase b and the later development of systematic attempts to fit the data into comprehensive theoretical models. Work from our own laboratory is emphasized, but we try to integrate this into the results from other investigators and show their contributions to our ideas and experiments. Finally, some recent unpublished data is presented together with some conclusions and predictions from a new hypothesis. The discoveries by Carl and Gerty Cori of the activation of phosphorylase by AMP, the inhibition of glucose and the enzymatic interconversion of two forms fo the enzyme with different control properties helped lay the foundations of our present understanding of allosteric mechanisms. The later discovery of the oligomeric nature of phosphorylase and its relationship to AMP binding served as a basis for many years of research into the structure-function relationships of phosphorylase and other enzymes. Data showing that AMP lowers the entropy of activation is discussed with respect to the role of the nucleotide and its binding close to the active site. The discovery of the control of phosphorylase b by common metabolites and the impetus this gave to the intensive kinetic studies of the last ten years, wherein fitting to theoretical models has been a common feature, is reviewed.

Avatars and computer-mediated communication: a review of the definitions, uses, and effects of digital representations

OpenAIRE

Nowak, Kristine L.; Fox, Jesse

2018-01-01

Avatars are growing in popularity and present in many interfaces used for computer-mediated communication (CMC) including social media, e-commerce, and education. Communication researchers have been investigating avatars for over twenty years, and an examination of this literature reveals similarities but also notable discrepancies in conceptual definitions. The goal of this review is to provide a general overview of current debates, methodological approaches, and trends in findings. Our revi...

The Role of Protein-Ligand Contacts in Allosteric Regulation of the Escherichia coli Catabolite Activator Protein.

Science.gov (United States)

Townsend, Philip D; Rodgers, Thomas L; Glover, Laura C; Korhonen, Heidi J; Richards, Shane A; Colwell, Lucy J; Pohl, Ehmke; Wilson, Mark R; Hodgson, David R W; McLeish, Tom C B; Cann, Martin J

2015-09-04

Allostery is a fundamental process by which ligand binding to a protein alters its activity at a distant site. Both experimental and theoretical evidence demonstrate that allostery can be communicated through altered slow relaxation protein dynamics without conformational change. The catabolite activator protein (CAP) of Escherichia coli is an exemplar for the analysis of such entropically driven allostery. Negative allostery in CAP occurs between identical cAMP binding sites. Changes to the cAMP-binding pocket can therefore impact the allosteric properties of CAP. Here we demonstrate, through a combination of coarse-grained modeling, isothermal calorimetry, and structural analysis, that decreasing the affinity of CAP for cAMP enhances negative cooperativity through an entropic penalty for ligand binding. The use of variant cAMP ligands indicates the data are not explained by structural heterogeneity between protein mutants. We observe computationally that altered interaction strength between CAP and cAMP variously modifies the change in allosteric cooperativity due to second site CAP mutations. As the degree of correlated motion between the cAMP-contacting site and a second site on CAP increases, there is a tendency for computed double mutations at these sites to drive CAP toward noncooperativity. Naturally occurring pairs of covarying residues in CAP do not display this tendency, suggesting a selection pressure to fine tune allostery on changes to the CAP ligand-binding pocket without a drive to a noncooperative state. In general, we hypothesize an evolutionary selection pressure to retain slow relaxation dynamics-induced allostery in proteins in which evolution of the ligand-binding site is occurring. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Are socioeconomic disparities in health behavior mediated by differential media use? Test of the communication inequality theory.

Science.gov (United States)

Ishikawa, Yoshiki; Kondo, Naoki; Kawachi, Ichiro; Viswanath, Kasisomayajula

2016-11-01

Communication inequality has been offered as one potential mechanism through which social determinants influence multiple health behaviors. The purpose of this study was to examine the underlying mechanisms between communication inequality and health behaviors. Data from a nationally representative cross-sectional survey of 18,426 people aged 18 years and above in the United States were used for secondary analysis. Measures included socio-demographic characteristics, social participation (structural social capital), health media use (TV, print, and the Internet), and five health behaviors (physical activity, cigarette smoking, alcohol use, and intake of fruit and vegetable). Path analysis was performed to examine the linkages between social determinants, health media use, social participation, and social gradients in health behaviors. Path analysis revealed that socioeconomic gradients in health behaviors is mediated by: 1) inequalities in health media use; 2) disparities in social participation, which leads to differential media use; and 3) disparities in social participation that are not mediated by media use. Consistent with the theory of communication inequality, socioeconomic disparities in media use partially mediate disparities in multiple health behaviors. To address health inequalities, it is important to utilize health media to target populations with low socioeconomic statuses. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Orthosteric and Allosteric Regulation in Trypsin-Like Peptidases

DEFF Research Database (Denmark)

Kromann-Tofting, Tobias

Trypsin-like serine peptidases play an important role in many physiological and pathophysiological processes, the latter including cardiovascular diseases and cancer. Binding of natural ligands to functional sites on the peptidase surface balances the level of activity and substrate specificity......-ray crystallography to determine crystal structures of active and inactive conformations of muPA, combined with biochemical analysis, elucidated an allosteric regulatory mechanism, which is now believed to be highly conserved in the trypsin-like serine peptidases. Targeting zymogen activation represents an attractive...

Fluid Centrality: A Social Network Analysis of Social-Technical Relations in Computer-Mediated Communication

Science.gov (United States)

Enriquez, Judith Guevarra

2010-01-01

In this article, centrality is explored as a measure of computer-mediated communication (CMC) in networked learning. Centrality measure is quite common in performing social network analysis (SNA) and in analysing social cohesion, strength of ties and influence in CMC, and computer-supported collaborative learning research. It argues that measuring…

Allosteric regulation by oleamide of the binding properties of 5-hydroxytryptamine7 receptors.

Science.gov (United States)

Hedlund, P B; Carson, M J; Sutcliffe, J G; Thomas, E A

1999-12-01

Oleamide belongs to a family of amidated lipids with diverse biological activities, including sleep induction and signaling modulation of several 5-hydroxytryptamine (5-HT) receptor subtypes, including 5-HT1A, 5-HT2A/2C, and 5-HT7. The 5-HT7 receptor, predominantly localized in the hypothalamus, hippocampus, and frontal cortex, stimulates cyclic AMP formation and is thought to be involved in the regulation of sleep-wake cycles. Recently, it was proposed that oleamide acts at an allosteric site on the 5-HT7 receptor to regulate cyclic AMP formation. We have further investigated the interaction between oleamide and 5-HT7 receptors by performing radioligand binding assays with HeLa cells transfected with the 5-HT7 receptor. Methiothepin, clozapine, and 5-HT all displaced specific [3H]5-HT (100 nM) binding, with pK(D) values of 7.55, 7.85, and 8.39, respectively. Oleamide also displaced [3H]5-HT binding, but the maximum inhibition was only 40% of the binding. Taking allosteric (see below) cooperativity into account, a K(D) of 2.69 nM was calculated for oleamide. In saturation binding experiments, oleamide caused a 3-fold decrease in the affinity of [3H]5-HT for the 5-HT7 receptor, without affecting the number of binding sites. A Schild analysis showed that the induced shift in affinity of [3H]5-HT reached a plateau, unlike that of a competitive inhibitor, illustrating the allosteric nature of the interaction between oleamide and the 5-HT7 receptor. Oleic acid, the product of oleamide hydrolysis, had a similar effect on [3H]5-HT binding, whereas structural analogs of oleamide, trans-9,10-octadecenamide, cis-8,9-octadecenamide, and erucamide, did not alter [3H]5-HT binding significantly. The findings support the hypothesis that oleamide acts via an allosteric site on the 5-HT7 receptor regulating receptor affinity.

Does contemporary computer-mediated epistolary communication need pedagogical interventions: The case of a student-teacher relationship

Directory of Open Access Journals (Sweden)

Prodanović Marijana M.

2016-01-01

Full Text Available The vast majority of messages we exchange on a daily basis is digital in its nature, and it could be said that computer-mediated communication has become common in all spheres of human endeavour. Despite the fact that CMC is an omnipresent phenomenon, it is usually the case that the choices regarding the language patterns to be used are made on our own; namely, it seems that there is no precise writing etiquette to be followed. This aim of this paper is to analyse the nature of computer-mediated communication performed in an academic environment. Using a language corpus composed of authentic email requests, sent by university students (Serbian native speakers to a faculty staff member, in a time frame encompassing a few semesters, the language formulae used in email openings and closings and the orientation of the posed requestive head acts have been examined. The results of the analysis have shown that hearer orientation is dominantly employed in the requests and that the choices with regard to salutations and complimentary closings are rather inconsistent. Finally, the study answers questions regarding the appropriateness of such e-communication patterns; it also sheds some light on the role of educators and/or educational institutions in communication processes of this kind and their forms.

[Pharmacological characteristics of drugs targeted on calcium-sensing receptor.-properties of cinacalcet hydrochloride as allosteric modulator].

Science.gov (United States)

Nagano, Nobuo; Tsutsui, Takaaki

2016-06-01

Calcimimetics act as positive allosteric modulators of the calcium-sensing receptor (CaSR), thereby decreasing parathyroid hormone (PTH) secretion from the parathyroid glands. On the other hand, negative allosteric modulators of the CaSR with stimulatory effect on PTH secretion are termed calcilytics. The calcimimetic cinacalcet hydrochloride (cinacalcet) is the world's first allosteric modulator of G protein-coupled receptor to enter the clinical market. Cinacalcet just tunes the physiological effects of Ca(2+), an endogenous ligand, therefore, shows high selectivity and low side effects. Calcimimetics also increase cell surface CaSR expression by acting as pharmacological chaperones (pharmacoperones). It is considered that the cinacalcet-induced upper gastrointestinal problems are resulted from enhanced physiological responses to Ca(2+) and amino acids via increased sensitivity of digestive tract CaSR by cinacalcet. While clinical developments of calcilytics for osteoporosis were unfortunately halted or terminated due to paucity of efficacy, it is expected that calcilytics may be useful for the treatment of patients with activating CaSR mutations, asthma, and idiopathic pulmonary artery hypertension.

Conopeptide ρ-TIA defines a new allosteric site on the extracellular surface of the α1B-adrenoceptor.

Science.gov (United States)

Ragnarsson, Lotten; Wang, Ching-I Anderson; Andersson, Åsa; Fajarningsih, Dewi; Monks, Thea; Brust, Andreas; Rosengren, K Johan; Lewis, Richard J

2013-01-18

The G protein-coupled receptor (GPCR) superfamily is an important drug target that includes over 1000 membrane receptors that functionally couple extracellular stimuli to intracellular effectors. Despite the potential of extracellular surface (ECS) residues in GPCRs to interact with subtype-specific allosteric modulators, few ECS pharmacophores for class A receptors have been identified. Using the turkey β(1)-adrenergic receptor crystal structure, we modeled the α(1B)-adrenoceptor (α(1B)-AR) to help identify the allosteric site for ρ-conopeptide TIA, an inverse agonist at this receptor. Combining mutational radioligand binding and inositol 1-phosphate signaling studies, together with molecular docking simulations using a refined NMR structure of ρ-TIA, we identified 14 residues on the ECS of the α(1B)-AR that influenced ρ-TIA binding. Double mutant cycle analysis and docking confirmed that ρ-TIA binding was dominated by a salt bridge and cation-π between Arg-4-ρ-TIA and Asp-327 and Phe-330, respectively, and a T-stacking-π interaction between Trp-3-ρ-TIA and Phe-330. Water-bridging hydrogen bonds between Asn-2-ρ-TIA and Val-197, Trp-3-ρ-TIA and Ser-318, and the positively charged N terminus and Glu-186, were also identified. These interactions reveal that peptide binding to the ECS on transmembrane helix 6 (TMH6) and TMH7 at the base of extracellular loop 3 (ECL3) is sufficient to allosterically inhibit agonist signaling at a GPCR. The ligand-accessible ECS residues identified provide the first view of an allosteric inhibitor pharmacophore for α(1)-adrenoceptors and mechanistic insight and a new set of structural constraints for the design of allosteric antagonists at related GPCRs.

Identity and collective action via computer-mediated communication: A review and agenda for future research

NARCIS (Netherlands)

Priante, Anna; Ehrenhard, Michel L; van den Broek, Tijs; Need, Ariana

2017-01-01

Since the start of large-scale waves of mobilisation in 2011, the importance of identity in the study of collective action via computer-mediated communication (CMC) has been a source of contention. Hence, our research sets out to systematically review and synthesise empirical findings on identity

Identity and collective action via computer-mediated communication : A review and agenda for future research

NARCIS (Netherlands)

Priante, Anna; Ehrenhard, Michel Léon; van den Broek, Tijs Adriaan; Need, Ariana

2017-01-01

Since the start of large-scale waves of mobilisation in 2011, the importance of identity in the study of collective action via computer-mediated communication (CMC) has been a source of contention. Hence, our research sets out to systematically review and synthesise empirical findings on identity

The Mediating Role of Partner Communication Frequency on Condom Use Among African-American Adolescent Females Participating in an HIV Prevention Intervention

Science.gov (United States)

Sales, Jessica M.; Lang, Delia L.; DiClemente, Ralph J.; Latham, Teaniese P; Wingood, Gina M.; Hardin, James W.; Rose, Eve S.

2011-01-01

Objective Although effective HIV prevention interventions have been developed for adolescents, few interventions have explored whether components of the intervention are responsible for the observed changes in behaviors post-intervention. This study examined the mediating role of partner communication frequency on African-American adolescent females’ condom use post-participation in a demonstrated efficacious HIV risk-reduction intervention. Main Outcome Measures Percent condom use in the past 60 days and consistent condom use in the past 6o days across the 12-month follow-up period. Design As part of a randomized controlled trial of African-American adolescent females (N=715), 15-21 years, seeking sexual health services, completed a computerized interview at baseline (prior to intervention) and again 6- and 12-month follow-up post-intervention participation. The interview assessed adolescents’ sexual behavior and partner communication skills, among other variables, at each time point. Using generalized estimating equation (GEE) techniques, both logistic and linear regression models were employed to test mediation over the 12-month follow-up period. Additional tests were conducted to assess the significance of the mediated models. Results Mediation analyses observed that partner communication frequency was a significant partial mediator of both proportion condom-protected sex acts (p =.001) and consistent condom use (p = .001). Conclusion Partner communication frequency, an integral component of this HIV intervention, significantly increased as a function of participating in the intervention partially explaining the change in condom use observed 12-months post-intervention. Understanding what intervention components are associated with behavior change is important for future intervention development. PMID:21843001

Shift in the Equilibrium between On and Off States of the Allosteric Switch in Ras-GppNHp Affected by Small Molecules and Bulk Solvent Composition

Energy Technology Data Exchange (ETDEWEB)

Holzapfel, Genevieve; Buhrman, Greg; Mattos, Carla (NCSU)

2012-08-31

Ras GTPase cycles between its active GTP-bound form promoted by GEFs and its inactive GDP-bound form promoted by GAPs to affect the control of various cellular functions. It is becoming increasingly apparent that subtle regulation of the GTP-bound active state may occur through promotion of substates mediated by an allosteric switch mechanism that induces a disorder to order transition in switch II upon ligand binding at an allosteric site. We show with high-resolution structures that calcium acetate and either dithioerythritol (DTE) or dithiothreitol (DTT) soaked into H-Ras-GppNHp crystals in the presence of a moderate amount of poly(ethylene glycol) (PEG) can selectively shift the equilibrium to the 'on' state, where the active site appears to be poised for catalysis (calcium acetate), or to what we call the 'ordered off' state, which is associated with an anticatalytic conformation (DTE or DTT). We also show that the equilibrium is reversible in our crystals and dependent on the nature of the small molecule present. Calcium acetate binding in the allosteric site stabilizes the conformation observed in the H-Ras-GppNHp/NOR1A complex, and PEG, DTE, and DTT stabilize the anticatalytic conformation observed in the complex between the Ras homologue Ran and Importin-{beta}. The small molecules are therefore selecting biologically relevant conformations in the crystal that are sampled by the disordered switch II in the uncomplexed GTP-bound form of H-Ras. In the presence of a large amount of PEG, the ordered off conformation predominates, whereas in solution, in the absence of PEG, switch regions appear to remain disordered in what we call the off state, unable to bind DTE.

Allosteric Binding in the Serotonin Transporter - Pharmacology, Structure, Function and Potential Use as a Novel Drug Target

DEFF Research Database (Denmark)

Loland, Claus J.; Sanchez, Connie; Plenge, Per

2017-01-01

The serotonin transporter (SERT) is an important drug target and the majority of currently used antidepressants are potent inhibitors of SERT, binding primarily to the substrate binding site. However, even though the existence of an allosteric modulator site was realized more than 30 years ago......, the research into this mechanism is still in its early days. The current knowledge about the allosteric site with respect to pharmacology, structure and function, and pharmacological tool compounds, is reviewed and a perspective is given on its potential as a drug target....

Talking about Quitting: Interpersonal Communication as a Mediator of Campaign Effects on Smokers’ Quit Behaviors

Science.gov (United States)

Jeong, Michelle; Tan, Andy; Brennan, Emily; Gibson, Laura; Hornik, Robert C.

2015-01-01

This study examined the role of interpersonal communication in the context of a mass media anti-smoking campaign. Specifically, it explored whether conversations about campaign ads and/or about quitting mediated campaign exposure effects on two quitting behaviors (sought help to quit and tried to quit smoking completely), as well as the relationship between ad-related and quitting-related conversations. Data were collected prior to the campaign and monthly for 16 months during the campaign through cross-sectional telephone surveys among a sample of 3277 adult Philadelphian smokers. Follow-up interviews were conducted among 877 participants three months after their first survey. Cross-sectional and longitudinal mediation models with bootstrap procedures assessed the indirect effects of campaign exposure on outcomes through conversations, and of conversations about ads on outcomes through conversations about quitting. In addition, lagged regression analyses tested the causal direction of associations between the variables of interest. The results partially support hypotheses that conversations about quitting mediate campaign effects on quitting-related behaviors, and, in line with previous research, that conversations about the ads have indirect effects on quitting-related behaviors by triggering conversations about quitting. These findings demonstrate the importance of considering interpersonal communication as a route of campaign exposure effects when evaluating and designing future public health campaigns. PMID:26147367

The sociocognitive psychology of computer-mediated communication: the present and future of technology-based interactions.

Science.gov (United States)

Riva, Giuseppe

2002-12-01

The increased diffusion of the Internet has made computer-mediated communication (CMC) very popular. However, a difficult question arises for psychologists and communication researchers: "What are the communicative characteristics of CMC?" According to the "cues-filtered-out" approach, CMC lacks the specifically relational features (social cues), which enable the interlocutors to identify correctly the kind of interpersonal situations they find themselves in. This paper counters this vision by integrating in its theoretical frame the different psycho-social approaches available in current literature. In particular, the paper describes the characteristics of the socio-cognitive processes-emotional expression, context definition, and identity creation-used by the interlocutors to make order and create relationships out of the miscommunication processes typical of CMC. Moreover, it presents the emerging forms of CMC-instant messaging, shared hypermedia, weblogs, and graphical chats-and their possible social and communicative effects.

Visualization of N-acylhomoserine lactone-mediated cell-cell communication between bacteria colonizing the tomato rhizosphere

DEFF Research Database (Denmark)

Steidle, A.; Sigl, K.; Schuhegger, R.

2001-01-01

developed and characterized novel Gfp-based monitor strains that allow in situ visualization of AHL-mediated communication between individual cells in the plant rhizosphere. For this purpose, three Gfp-based AHL sensor plasmids that respond to different spectra of AHL molecules were transferred into AHL......-negative derivatives of Pseudomonas putida IsoF and Serratia liquefaciens MG1, two strains that are capable of colonizing tomato roots. These AHL monitor strains were used to visualize communication between defined bacterial populations in the rhizosphere of axenically grown tomato plants. Furthermore, we integrated...

SERVANT LEADERSHIP AND ORGANIZATIONAL TRUST: THE MEDIATING EFFECT OF THE LEADER TRUST AND ORGANIZATIONAL COMMUNICATION

Directory of Open Access Journals (Sweden)

Morad Rezaei

2012-01-01

Full Text Available The purpose of this paper aims to clarify the relationship between servant leadership and organizational trust, and tries to demonstrate the mediator role of leader trust and organizational communication in this relationship. The study sample included 258 employees of Guilan province Tax Administration and for sampling we used cluster method. Previous studies have also focused on the positive impact of servant leadership in organizational trust and in this article the results show that there is a significant relationship between servant leadership, organizational trust, leader trust and organizational communication.

Tissue factor activates allosteric networks in factor VIIa through structural and dynamic changes

DEFF Research Database (Denmark)

Madsen, Jesper Jonasson; Persson, E.; Olsen, O. H.

2015-01-01

that are not likely to be inferred from mutagenesis studies. Furthermore, paths from Met306 to Ile153 (N-terminus) and Trp364, both representing hallmark residues of allostery, are 7% and 37% longer, respectively, in free FVIIa. Thus, there is significantly weaker coupling between the TF contact point and key......Background: Tissue factor (TF) promotes colocalization of enzyme (factorVIIa) and substrate (FX or FIX), and stabilizes the active conformation of FVIIa. Details on how TF induces structural and dynamic changes in the catalytic domain of FVIIa to enhance its efficiency remain elusive. Objective......: To elucidate the activation of allosteric networks in the catalytic domain of the FVIIa protease it is when bound to TF.MethodsLong-timescale molecular dynamics simulations of FVIIa, free and in complex with TF, were executed and analyzed by dynamic network analysis. Results: Allosteric paths of correlated...

Identity as a Moderator and Mediator of Communication Effects: Evidence and Implications for Message Design.

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Comello, Maria Leonora G; Farman, Lisa

2016-10-02

Advertisements, movies, and other forms of media content have potential to change behaviors and antecedent psychological states by appealing to identity. However, the mechanisms that are responsible for persuasive effects of such content have not been adequately specified. A recently proposed model of communication effects (the prism model) advances the study of mechanisms and argues that identity can serve as both a moderator and mediator of communication effects on behavior-relevant outcomes. These intervening roles are made possible by the complex nature of identity (including multiple self-concepts and sensitivity to cues) and messages that cue the importance of and activate particular self-concepts. This article builds on development of the model by presenting empirical support based on re-analysis of an experiment in which participants viewed either a more-stigmatizing or less-stigmatizing portrayal of a recovering drug addict. In line with the model's propositions, exposure to the less-stigmatizing condition led to increases in perspective taking which then led to more acceptance (mediation by identity), while level of perspective taking also changed the effect of condition on acceptance (moderation by identity). These results provide support for the model's proposition of simultaneous intervening roles. The authors discuss implications for strategic communication research and practice.

Patient health communication mediating effects between gastrointestinal symptoms and gastrointestinal worry in pediatric inflammatory bowel disease

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To investigate the effects of patient health communication regarding their inflammatory bowel disease (IBD) to their health care providers and significant others in their daily life as a mediator in the relationship between gastrointestinal symptoms and gastrointestinal worry in pediatric patients. ...

Orthosteric and allosteric potentiation of heteromeric neuronal nicotinic acetylcholine receptors.

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Wang, Jingyi; Lindstrom, Jon

2018-06-01

Heteromeric nicotinic ACh receptors (nAChRs) were thought to have two orthodox agonist-binding sites at two α/β subunit interfaces. Highly selective ligands are hard to develop by targeting orthodox agonist sites because of high sequence similarity of this binding pocket among different subunits. Recently, unorthodox ACh-binding sites have been discovered at some α/α and β/α subunit interfaces, such as α4/α4, α5/α4 and β3/α4. Targeting unorthodox sites may yield subtype-selective ligands, such as those for (α4β2) 2 α5, (α4β2) 2 β3 and (α6β2) 2 β3 nAChRs. The unorthodox sites have unique pharmacology. Agonist binding at one unorthodox site is not sufficient to activate nAChRs, but it increases activation from the orthodox sites. NS9283, a selective agonist for the unorthodox α4/α4 site, was initially thought to be a positive allosteric modulator (PAM). NS9283 activates nAChRs with three engineered α4/α4 sites. PAMs, on the other hand, act at allosteric sites where ACh cannot bind. Known PAM sites include the ACh-homologous non-canonical site (e.g. morantel at β/α), the C-terminus (e.g. Br-PBTC and 17β-estradiol), a transmembrane domain (e.g. LY2087101) or extracellular and transmembrane domain interfaces (e.g. NS206). Some of these PAMs, such as Br-PBTC and 17β-estradiol, require only one subunit to potentiate activation of nAChRs. In this review, we will discuss differences between activation from orthosteric and allosteric sites, their selective ligands and clinical implications. These studies have advanced understanding of the structure, assembly and pharmacology of heteromeric neuronal nAChRs. This article is part of a themed section on Nicotinic Acetylcholine Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.11/issuetoc. © 2017 The British Pharmacological Society.

Evaluating Critical Thinking in Computer Mediated Communication Discussions

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Faizah Mohamad

2008-06-01

Full Text Available This paper presents an investigation of whether computer mediated communication (CMC can develop critical thinking in language classrooms. The research was conducted at a university branch campus in Malaysia over a period of 12 weeks. It involved three groups of learners in which each group was exposed to different discussion modes. The first group was exposed to a CMC discussion mode, the second group was exposed to a mixed mode of CMC and face-to-face (F2F discussions and the third group had only the face-to-face mode of discussion. The critical thinking development in these three conditions was evaluated based on the content analysis method used by Newman, Johnson, Cochrane and Webb (1995. This research reports the findings which hopefully will give some insight to other teaching practitioners who are interested in incorporating IT in their classrooms

The tertiary origin of the allosteric activation of E. coli glucosamine-6-phosphate deaminase studied by sol-gel nanoencapsulation of its T conformer.

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Sergio Zonszein

Full Text Available The role of tertiary conformational changes associated to ligand binding was explored using the allosteric enzyme glucosamine-6-phosphate (GlcN6P deaminase from Escherichia coli (EcGNPDA as an experimental model. This is an enzyme of amino sugar catabolism that deaminates GlcN6P, giving fructose 6-phosphate and ammonia, and is allosterically activated by N-acetylglucosamine 6-phosphate (GlcNAc6P. We resorted to the nanoencapsulation of this enzyme in wet silica sol-gels for studying the role of intrasubunit local mobility in its allosteric activation under the suppression of quaternary transition. The gel-trapped enzyme lost its characteristic homotropic cooperativity while keeping its catalytic properties and the allosteric activation by GlcNAc6P. The nanoencapsulation keeps the enzyme in the T quaternary conformation, making possible the study of its allosteric activation under a condition that is not possible to attain in a soluble phase. The involved local transition was slowed down by nanoencapsulation, thus easing the fluorometric analysis of its relaxation kinetics, which revealed an induced-fit mechanism. The absence of cooperativity produced allosterically activated transitory states displaying velocity against substrate concentration curves with apparent negative cooperativity, due to the simultaneous presence of subunits with different substrate affinities. Reaction kinetics experiments performed at different tertiary conformational relaxation times also reveal the sequential nature of the allosteric activation. We assumed as a minimal model the existence of two tertiary states, t and r, of low and high affinity, respectively, for the substrate and the activator. By fitting the velocity-substrate curves as a linear combination of two hyperbolic functions with Kt and Kr as KM values, we obtained comparable values to those reported for the quaternary conformers in solution fitted to MWC model. These results are discussed in the

Dual interaction of agmatine with the rat α2D-adrenoceptor: competitive antagonism and allosteric activation

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Molderings, G J; Menzel, S; Kathmann, M; Schlicker, E; Göthert, M

2000-01-01

In segments of rat vena cava preincubated with [3H]-noradrenaline and superfused with physiological salt solution, the influence of agmatine on the electrically evoked [3H]-noradrenaline release, the EP3 prostaglandin receptor-mediated and the α2D-adrenoceptor-mediated inhibition of evoked [3H]-noradrenaline release was investigated. Agmatine (0.1–10 μM) by itself was without effect on evoked [3H]-noradrenaline release. In the presence of 10 μM agmatine, the prostaglandin E2(PGE2)-induced EP3-receptor-mediated inhibition of [3H]-noradrenaline release was not modified, whereas the α2D-adrenoceptor-mediated inhibition of [3H]-noradrenaline release induced by noradrenaline, moxonidine or clonidine was more pronounced than in the absence of agmatine. However, 1 mM agmatine antagonized the moxonidine-induced inhibition of [3H]-noradrenaline release. Agmatine concentration-dependently inhibited the binding of [3H]-clonidine and [3H]-rauwolscine to rat brain cortex membranes (Ki values 6 μM and 12 μM, respectively). In addition, 30 and 100 μM agmatine increased the rate of association and decreased the rate of dissociation of [3H]-clonidine resulting in an increased affinity of the radioligand for the α2D-adrenoceptors. [14C]-agmatine labelled specific binding sites on rat brain cortex membranes. In competition experiments. [14C]-agmatine was inhibited from binding to its specific recognition sites by unlabelled agmatine, but not by rauwolscine and moxonidine. In conclusion, the present data indicate that agmatine both acts as an antagonist at the ligand recognition site of the α2D-adrenoceptor and enhances the effects of α2-adrenoceptor agonists probably by binding to an allosteric binding site of the α2D-adrenoceptor which seems to be labelled by [14C]-agmatine. PMID:10928978

Conopeptide ρ-TIA Defines a New Allosteric Site on the Extracellular Surface of the α1B-Adrenoceptor*♦

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Ragnarsson, Lotten; Wang, Ching-I Anderson; Andersson, Åsa; Fajarningsih, Dewi; Monks, Thea; Brust, Andreas; Rosengren, K. Johan; Lewis, Richard J.

2013-01-01

The G protein-coupled receptor (GPCR) superfamily is an important drug target that includes over 1000 membrane receptors that functionally couple extracellular stimuli to intracellular effectors. Despite the potential of extracellular surface (ECS) residues in GPCRs to interact with subtype-specific allosteric modulators, few ECS pharmacophores for class A receptors have been identified. Using the turkey β1-adrenergic receptor crystal structure, we modeled the α1B-adrenoceptor (α1B-AR) to help identify the allosteric site for ρ-conopeptide TIA, an inverse agonist at this receptor. Combining mutational radioligand binding and inositol 1-phosphate signaling studies, together with molecular docking simulations using a refined NMR structure of ρ-TIA, we identified 14 residues on the ECS of the α1B-AR that influenced ρ-TIA binding. Double mutant cycle analysis and docking confirmed that ρ-TIA binding was dominated by a salt bridge and cation-π between Arg-4-ρ-TIA and Asp-327 and Phe-330, respectively, and a T-stacking-π interaction between Trp-3-ρ-TIA and Phe-330. Water-bridging hydrogen bonds between Asn-2-ρ-TIA and Val-197, Trp-3-ρ-TIA and Ser-318, and the positively charged N terminus and Glu-186, were also identified. These interactions reveal that peptide binding to the ECS on transmembrane helix 6 (TMH6) and TMH7 at the base of extracellular loop 3 (ECL3) is sufficient to allosterically inhibit agonist signaling at a GPCR. The ligand-accessible ECS residues identified provide the first view of an allosteric inhibitor pharmacophore for α1-adrenoceptors and mechanistic insight and a new set of structural constraints for the design of allosteric antagonists at related GPCRs. PMID:23184947

Piracetam defines a new binding site for allosteric modulators of alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptors.

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Ahmed, Ahmed H; Oswald, Robert E

2010-03-11

Glutamate receptors are the most prevalent excitatory neurotransmitter receptors in the vertebrate central nervous system and are important potential drug targets for cognitive enhancement and the treatment of schizophrenia. Allosteric modulators of AMPA receptors promote dimerization by binding to a dimer interface and reducing desensitization and deactivation. The pyrrolidine allosteric modulators, piracetam and aniracetam, were among the first of this class of drugs to be discovered. We have determined the structure of the ligand binding domain of the AMPA receptor subtypes GluA2 and GluA3 with piracetam and a corresponding structure of GluA3 with aniracetam. Both drugs bind to GluA2 and GluA3 in a very similar manner, suggesting little subunit specificity. However, the binding sites for piracetam and aniracetam differ considerably. Aniracetam binds to a symmetrical site at the center of the dimer interface. Piracetam binds to multiple sites along the dimer interface with low occupation, one of which is a unique binding site for potential allosteric modulators. This new site may be of importance in the design of new allosteric regulators.

Computer-mediated communication preferences predict biobehavioral measures of social-emotional functioning.

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Babkirk, Sarah; Luehring-Jones, Peter; Dennis-Tiwary, Tracy A

2016-12-01

The use of computer-mediated communication (CMC) as a form of social interaction has become increasingly prevalent, yet few studies examine individual differences that may shed light on implications of CMC for adjustment. The current study examined neurocognitive individual differences associated with preferences to use technology in relation to social-emotional outcomes. In Study 1 (N = 91), a self-report measure, the Social Media Communication Questionnaire (SMCQ), was evaluated as an assessment of preferences for communicating positive and negative emotions on a scale ranging from purely via CMC to purely face-to-face. In Study 2, SMCQ preferences were examined in relation to event-related potentials (ERPs) associated with early emotional attention capture and reactivity (the frontal N1) and later sustained emotional processing and regulation (the late positive potential (LPP)). Electroencephalography (EEG) was recorded while 22 participants passively viewed emotional and neutral pictures and completed an emotion regulation task with instructions to increase, decrease, or maintain their emotional responses. A greater preference for CMC was associated with reduced size of and satisfaction with social support, greater early (N1) attention capture by emotional stimuli, and reduced LPP amplitudes to unpleasant stimuli in the increase emotion regulatory task. These findings are discussed in the context of possible emotion- and social-regulatory functions of CMC.

Exploring the use of computer-mediated video communication in engineering projects in South Africa

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Meyer, Izak P.

2016-08-01

Full Text Available Globally-expanding organisations that are trying to capitalise on distributed skills are increasingly using virtual project teams to shorten product development time and increase quality. These virtual teams, which are distributed across countries, cultures, and time zones, are required to use faster and better ways of interacting. Past research has shown that virtual teams that use computer-mediated communication (CMC instead of face-to-face communication are less cohesive because they struggle with mistrust, controlling behaviour , and communication breakdowns. This study aims to determine whether project practitioners in South Africa perceive virtual teams that use videoconferencing as suffering from the same CMC disadvantages described in past research in other environments; and if they do, what the possible causes could be. This paper reports on a survey of 106 project practitioners in South Africa. The results show that these project practitioners prefer face- to-face communication over CMC, and perceive virtual teams using videoconferencing to be less cohesive and to suffer from mistrust and communication breakdowns, but not from increased conflict and power struggles. The perceived shortcomings of videoconferencing might result from virtual teams that use this medium having less time to build interpersonal relationships.

Information Technology as the Paradigm High-Speed Management Support Tool: The Uses of Computer Mediated Communication, Virtual Realism, and Telepresence.

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Newby, Gregory B.

Information technologies such as computer mediated communication (CMC), virtual reality, and telepresence can provide the communication flow required by high-speed management techniques that high-technology industries have adopted in response to changes in the climate of competition. Intra-corporate CMC might be used for a variety of purposes…

Sequence analysis and molecular characterization of Clonorchis sinensis hexokinase, an unusual trimeric 50-kDa glucose-6-phosphate-sensitive allosteric enzyme.

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Tingjin Chen

Full Text Available Clonorchiasis, which is induced by the infection of Clonorchis sinensis (C. sinensis, is highly associated with cholangiocarcinoma. Because the available examination, treatment and interrupting transmission provide limited opportunities to prevent infection, it is urgent to develop integrated strategies to prevent and control clonorchiasis. Glycolytic enzymes are crucial molecules for trematode survival and have been targeted for drug development. Hexokinase of C. sinensis (CsHK, the first key regulatory enzyme of the glycolytic pathway, was characterized in this study. The calculated molecular mass (Mr of CsHK was 50.0 kDa. The obtained recombinant CsHK (rCsHK was a homotrimer with an Mr of approximately 164 kDa, as determined using native PAGE and gel filtration. The highest activity was obtained with 50 mM glycine-NaOH at pH 10 and 100 mM Tris-HCl at pH 8.5 and 10. The kinetics of rCsHK has a moderate thermal stability. Compared to that of the corresponding negative control, the enzymatic activity was significantly inhibited by praziquantel (PZQ and anti-rCsHK serum. rCsHK was homotropically and allosterically activated by its substrates, including glucose, mannose, fructose, and ATP. ADP exhibited mixed allosteric effect on rCsHK with respect to ATP, while inorganic pyrophosphate (PPi displayed net allosteric activation with various allosteric systems. Fructose behaved as a dose-dependent V activator with the substrate glucose. Glucose-6-phosphate (G6P displayed net allosteric inhibition on rCsHK with respect to ATP or glucose with various allosteric systems in a dose-independent manner. There were differences in both mRNA and protein levels of CsHK among the life stages of adult worm, metacercaria, excysted metacercaria and egg of C. sinensis, suggesting different energy requirements during different development stages. Our study furthers the understanding of the biological functions of CsHK and supports the need to screen for small

Sequence Analysis and Molecular Characterization of Clonorchis sinensis Hexokinase, an Unusual Trimeric 50-kDa Glucose-6-Phosphate-Sensitive Allosteric Enzyme

Science.gov (United States)

Chen, Tingjin; Ning, Dan; Sun, Hengchang; Li, Ran; Shang, Mei; Li, Xuerong; Wang, Xiaoyun; Chen, Wenjun; Liang, Chi; Li, Wenfang; Mao, Qiang; Li, Ye; Deng, Chuanhuan; Wang, Lexun; Wu, Zhongdao; Huang, Yan; Xu, Jin; Yu, Xinbing

2014-01-01

Clonorchiasis, which is induced by the infection of Clonorchis sinensis (C. sinensis), is highly associated with cholangiocarcinoma. Because the available examination, treatment and interrupting transmission provide limited opportunities to prevent infection, it is urgent to develop integrated strategies to prevent and control clonorchiasis. Glycolytic enzymes are crucial molecules for trematode survival and have been targeted for drug development. Hexokinase of C. sinensis (CsHK), the first key regulatory enzyme of the glycolytic pathway, was characterized in this study. The calculated molecular mass (Mr) of CsHK was 50.0 kDa. The obtained recombinant CsHK (rCsHK) was a homotrimer with an Mr of approximately 164 kDa, as determined using native PAGE and gel filtration. The highest activity was obtained with 50 mM glycine-NaOH at pH 10 and 100 mM Tris-HCl at pH 8.5 and 10. The kinetics of rCsHK has a moderate thermal stability. Compared to that of the corresponding negative control, the enzymatic activity was significantly inhibited by praziquantel (PZQ) and anti-rCsHK serum. rCsHK was homotropically and allosterically activated by its substrates, including glucose, mannose, fructose, and ATP. ADP exhibited mixed allosteric effect on rCsHK with respect to ATP, while inorganic pyrophosphate (PPi) displayed net allosteric activation with various allosteric systems. Fructose behaved as a dose-dependent V activator with the substrate glucose. Glucose-6-phosphate (G6P) displayed net allosteric inhibition on rCsHK with respect to ATP or glucose with various allosteric systems in a dose-independent manner. There were differences in both mRNA and protein levels of CsHK among the life stages of adult worm, metacercaria, excysted metacercaria and egg of C. sinensis, suggesting different energy requirements during different development stages. Our study furthers the understanding of the biological functions of CsHK and supports the need to screen for small molecule inhibitors

Notes on stochastic (bio)-logic gates: computing with allosteric cooperativity.

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Agliari, Elena; Altavilla, Matteo; Barra, Adriano; Dello Schiavo, Lorenzo; Katz, Evgeny

2015-05-15

Recent experimental breakthroughs have finally allowed to implement in-vitro reaction kinetics (the so called enzyme based logic) which code for two-inputs logic gates and mimic the stochastic AND (and NAND) as well as the stochastic OR (and NOR). This accomplishment, together with the already-known single-input gates (performing as YES and NOT), provides a logic base and paves the way to the development of powerful biotechnological devices. However, as biochemical systems are always affected by the presence of noise (e.g. thermal), standard logic is not the correct theoretical reference framework, rather we show that statistical mechanics can work for this scope: here we formulate a complete statistical mechanical description of the Monod-Wyman-Changeaux allosteric model for both single and double ligand systems, with the purpose of exploring their practical capabilities to express noisy logical operators and/or perform stochastic logical operations. Mixing statistical mechanics with logics, and testing quantitatively the resulting findings on the available biochemical data, we successfully revise the concept of cooperativity (and anti-cooperativity) for allosteric systems, with particular emphasis on its computational capabilities, the related ranges and scaling of the involved parameters and its differences with classical cooperativity (and anti-cooperativity).

Computer Mediated Communication for Social and Academic Purposes: Profiles of Use and University Students' Gratifications

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Vrocharidou, Anatoli; Efthymiou, Ilias

2012-01-01

The present study approaches the Internet as a social space, where university students make use of computer mediated communication (CMC) applications, i.e. e-mail, instant messaging and social network sites, in order to satisfy social and academic needs. We focus on university students, because they represent one of the most avid groups of CMC…

The Nature of Negotiations in Face-to-Face versus Computer-Mediated Communication in Pair Interactions

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Rouhshad, Amir; Wigglesworth, Gillian; Storch, Neomy

2016-01-01

The Interaction Approach argues that negotiation for meaning and form is conducive to second language development. To date, most of the research on negotiations has been either in face-to-face (FTF) or text-based synchronous computer-mediated communication (SCMC) modes. Very few studies have compared the nature of negotiations across the modes.…

Computer-mediated communication and time pressure induce higher cardiovascular responses in the preparatory and execution phases of cooperative tasks.

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Costa Ferrer, Raquel; Serrano Rosa, Miguel Ángel; Zornoza Abad, Ana; Salvador Fernández-Montejo, Alicia

2010-11-01

The cardiovascular (CV) response to social challenge and stress is associated with the etiology of cardiovascular diseases. New ways of communication, time pressure and different types of information are common in our society. In this study, the cardiovascular response to two different tasks (open vs. closed information) was examined employing different communication channels (computer-mediated vs. face-to-face) and with different pace control (self vs. external). Our results indicate that there was a higher CV response in the computer-mediated condition, on the closed information task and in the externally paced condition. These role of these factors should be considered when studying the consequences of social stress and their underlying mechanisms.

[Web-ring of sites for pathologists in the internet: a computer-mediated communication environment].

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Khramtsov, A I; Isianov, N N; Khorzhevskiĭ, V A

2009-01-01

The recently developed Web-ring of pathology-related Web-sites has transformed computer-mediated communications for Russian-speaking pathologists. Though the pathologists may be geographically dispersed, the network provides a complex of asynchronous and synchronous conferences for the purposes of diagnosis, consultations, education, communication, and collaboration in the field of pathology. This paper describes approaches to be used by participants of the pathology-related Web-ring. The approaches are analogous to the tools employed in telepathology and digital microscopy. One of the novel methodologies is the use of Web-based conferencing systems, in which the whole slide digital images of tissue microarrays were jointly reviewed online by pathologists at distant locations. By using ImageScope (Aperio Technologies) and WebEx connect desktop management technology, they shared presentations and images and communicated in realtime. In this manner, the Web-based forums and conferences will be a powerful addition to a telepathology.

The effect of computer-mediated social support in online communities on patient empowerment and doctor-patient communication.

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Oh, Hyun Jung; Lee, Byoungkwan

2012-01-01

In the context of diabetes, this study tested a mechanism through which Korean diabetes patients' exchange of computer-mediated social support (CMSS) in diabetes online communities influences their sense of empowerment and intention to actively communicate with the doctor. Analysis of data from 464 Korean diabetes patients indicates significant relationships among diabetes patients' online community activities, perceived CMSS, sense of empowerment, and their intention to actively communicate with the doctor. Diabetes patients who have engaged more in online community activities perceived greater social support from other members of the community. Perceived CMSS significantly predicted their intention to actively communicate with the doctor through sense of empowerment. Sense of empowerment was a valid underlying mechanism that explains how patients' perceived CMSS influences their intention to actively communicate with the doctor. The implications for health communication research and practice are discussed.

Assessing the structural conservation of protein pockets to study functional and allosteric sites: implications for drug discovery

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Daura Xavier

2010-03-01

Full Text Available Abstract Background With the classical, active-site oriented drug-development approach reaching its limits, protein ligand-binding sites in general and allosteric sites in particular are increasingly attracting the interest of medicinal chemists in the search for new types of targets and strategies to drug development. Given that allostery represents one of the most common and powerful means to regulate protein function, the traditional drug discovery approach of targeting active sites can be extended by targeting allosteric or regulatory protein pockets that may allow the discovery of not only novel drug-like inhibitors, but activators as well. The wealth of available protein structural data can be exploited to further increase our understanding of allosterism, which in turn may have therapeutic applications. A first step in this direction is to identify and characterize putative effector sites that may be present in already available structural data. Results We performed a large-scale study of protein cavities as potential allosteric and functional sites, by integrating publicly available information on protein sequences, structures and active sites for more than a thousand protein families. By identifying common pockets across different structures of the same protein family we developed a method to measure the pocket's structural conservation. The method was first parameterized using known active sites. We characterized the predicted pockets in terms of sequence and structural conservation, backbone flexibility and electrostatic potential. Although these different measures do not tend to correlate, their combination is useful in selecting functional and regulatory sites, as a detailed analysis of a handful of protein families shows. We finally estimated the numbers of potential allosteric or regulatory pockets that may be present in the data set, finding that pockets with putative functional and effector characteristics are widespread across

Screening and identification of potential PTP1B allosteric inhibitors using in silico and in vitro approaches.

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Shinde, Ranajit Nivrutti; Kumar, G Siva; Eqbal, Shahbaz; Sobhia, M Elizabeth

2018-01-01

Protein tyrosine phosphatase 1B (PTP1B) is a validated therapeutic target for Type 2 diabetes due to its specific role as a negative regulator of insulin signaling pathways. Discovery of active site directed PTP1B inhibitors is very challenging due to highly conserved nature of the active site and multiple charge requirements of the ligands, which makes them non-selective and non-permeable. Identification of the PTP1B allosteric site has opened up new avenues for discovering potent and selective ligands for therapeutic intervention. Interactions made by potent allosteric inhibitor in the presence of PTP1B were studied using Molecular Dynamics (MD). Computationally optimized models were used to build separate pharmacophore models of PTP1B and TCPTP, respectively. Based on the nature of interactions the target residues offered, a receptor based pharmacophore was developed. The pharmacophore considering conformational flexibility of the residues was used for the development of pharmacophore hypothesis to identify potentially active inhibitors by screening large compound databases. Two pharmacophore were successively used in the virtual screening protocol to identify potential selective and permeable inhibitors of PTP1B. Allosteric inhibition mechanism of these molecules was established using molecular docking and MD methods. The geometrical criteria values confirmed their ability to stabilize PTP1B in an open conformation. 23 molecules that were identified as potential inhibitors were screened for PTP1B inhibitory activity. After screening, 10 molecules which have good permeability values were identified as potential inhibitors of PTP1B. This study confirms that selective and permeable inhibitors can be identified by targeting allosteric site of PTP1B.

Effects of Synchronous Computer-Mediated Communication and Face-to-Face Interaction on Speaking Skill Development of Iranian EFL Learners

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Hakimeh Shahrokhi Mehr

2013-09-01

Full Text Available The traditional form of teaching speaking skill has been via face-to-face (FTF interaction in the classroom setting. Today in the computer age, the on-line forum can provide a virtual environment for differential communication. The pedagogical system benefits from such technology improvement for teaching foreign languages. This quasi-experimental research aimed at comparing the effects of two instructional strategies: synchronous computer-mediated communication (SCMC and FTF interaction. For this purpose, 60 EFL learners were selected from a private language institute as the control (n=30 and experimental (n=30 groups. A speaking test, designed by Hughes (2003, was administered as pretest and after a 12-session treatment the same test was administered as the posttest. The result obtained showed that participants taught based on SCMC fared better than those that were taught according to FTF interaction. Based on the findings of the current study, it is recommended that EFL teachers incorporate computer-mediated communication into their pedagogical procedures.

Development of an experimental activity for teaching cooperativity and allosterism

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B. Manta

2006-07-01

Full Text Available Although  enzyme  control  and  regulation  is  an  important  topic  in  most  Biochemistry  and  Enzymology  courses, laboratory  activities  that  allow  an  experimental  approach  to  cooperativity  and  allosterism  are  difficult  to  implement. The objective of this work was to develop a simple and inexpensive experimental activity to teach this topic in basic courses.  We  decided  to  use  the  enzyme  glucosamine-6-phosphate  deaminase  (GNPD,  E.C.  3.5.99.6  from Escherichia coli,  that  is  both  kinetically  and  structurally  well-known.  GNPD  is  an  allosteric  enzyme,  activated  by  N-acetylglucosamine 6-phosphate, that catalyzes the conversion of glucosamine 6-phosphate into fructose 6-phosphate and  ammonia.  The  enzyme  is  a  typical  allosteric  K-system  and  can  be  well  described  by  the  Monod-Wyman-Changeux  (MWC  model.  GNPD  was  partially  purified  through  anionic-exchange  chromatography  from  a  mutant E.coli strain  which  expresses  constitutively  high  levels  of the  enzyme.  In  order  to  measure  activity  we  used  an end point  method  which  consists  in  stopping  the  reaction  at  a  certain  time  point  with  HCl  10  N,  and  quantifying  the fructose-6-phosphate  formed  with  resorcinol  (Selliwanoff  reaction  through  the  formation  of  a  red  color  that  is measured  spectrophotometrically.  We  developed  a  protocol  that  consisted  in  a  4-hour  experiment  in  which  the students  measured  the  activity  of  the  GNPD  with  increasing  concentrations  of  the  substrate,  in  the  presence  or absence  of  allosteric  modulator.  The  students  obtained  a  good  quality  data  set  that  they  analyzed  based  on  the equations  of  Hill,  MWC  and  Acerenza-Mirzaji �

Hydrogen bonds and heat diffusion in α-helices: a computational study.

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Miño, German; Barriga, Raul; Gutierrez, Gonzalo

2014-08-28

Recent evidence has shown a correlation between the heat diffusion pathways and the known allosteric communication pathways in proteins. Allosteric communication in proteins is a central, yet unsolved, problem in biochemistry, and the study and characterization of the structural determinants that mediate energy transfer among different parts of proteins is of major importance. In this work, we characterized the role of hydrogen bonds in diffusivity of thermal energy for two sets of α-helices with different abilities to form hydrogen bonds. These hydrogen bonds can be a constitutive part of the α-helices or can arise from the lateral chains. In our in vacuo simulations, it was observed that α-helices with a higher possibility of forming hydrogen bonds also had higher rates of thermalization. Our simulations also revealed that heat readily flowed through atoms involved in hydrogen bonds. As a general conclusion, according to our simulations, hydrogen bonds fulfilled an important role in heat diffusion in structural patters of proteins.

A large-scale allosteric transition in cytochrome P450 3A4 revealed by luminescence resonance energy transfer (LRET.

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Elena V Sineva

Full Text Available Effector-induced allosteric transitions in cytochrome P450 3A4 (CYP3A4 were investigated by luminescence resonance energy transfer (LRET between two SH-reactive probes attached to various pairs of distantly located cysteine residues, namely the double-cysteine mutants CYP3A4(C64/C468, CYP3A4(C377/C468 and CYP3A4(C64/C121. Successive equimolar labeling of these proteins with the phosphorescent probe erythrosine iodoacetamide (donor and the near-infrared fluorophore DY-731 maleimide (acceptor allowed us to establish donor/acceptor pairs sensitive to conformational motions. The interactions of all three double-labeled mutants with the allosteric activators α-naphthoflavone and testosterone resulted in an increase in the distance between the probes. A similar effect was elicited by cholesterol. These changes in distance vary from 1.3 to 8.5 Å, depending on the position of the donor/acceptor pair and the nature of the effector. In contrast, the changes in the interprobe distance caused by such substrates as bromocriptine or 1-pyrenebutanol were only marginal. Our results provide a decisive support to the paradigm of allosteric modulation of CYP3A4 and indicate that the conformational transition caused by allosteric effectors increases the spatial separation between the beta-domain of the enzyme (bearing residues Cys64 and Cys377 and the alpha-domain, where Cys121 and Cys468 are located.

Improvements in closeness, communication, and psychological distress mediate effects of couple therapy for veterans.

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Doss, Brian D; Mitchell, Alexandra; Georgia, Emily J; Biesen, Judith N; Rowe, Lorelei Simpson

2015-04-01

Empirically based couple therapy results in significant improvements in relationship satisfaction for the average couple; however, further research is needed to identify mediators that lead to change and to ensure that improvements in mediators predict subsequent-not just concurrent-relationship satisfaction. In addition, given that much of the current literature on couple therapy examines outcomes in a research environment, it is important to examine mediators in a treatment-as-usual setting. To address these questions, 161 heterosexual couples (322 individuals) received treatment-as-usual couple therapy at one of two Veteran Administration Medical Centers (M = 5.0 and 13.0 sessions at the two sites) and were assessed before every session. The majority of couples were married (85%) and had been together for a median of 7.8 years (SD = 13). Participants were primarily White, non-Hispanic (69%), African American (21%), and White, Hispanic/Latino (8%). Individuals' own self-reported improvements in communication, emotional closeness, and psychological distress (but not frequency of behaviors targeted in treatment) mediated the effect of treatment on their subsequent relationship satisfaction. When all significant mediators were examined simultaneously, improvements in men's and women's emotional closeness and men's psychological distress independently mediated subsequent relationship satisfaction. In contrast, improvements in earlier relationship satisfaction mediated the effect of treatment only on subsequent psychological distress. This study identifies unique mediators of treatment effects and shows that gains in mechanisms predict subsequent relationship satisfaction. Future investigations should focus on the role of emotional closeness and psychological distress-constructs that have often been neglected-in couple therapy. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

SB265610 is an allosteric, inverse agonist at the human CXCR2 receptor

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Bradley, ME; Bond, ME; Manini, J; Brown, Z; Charlton, SJ

2009-01-01

Background and purpose: In several previous studies, the C-X-C chemokine receptor (CXCR)2 antagonist 1-(2-bromo-phenyl)-3-(7-cyano-3H-benzotriazol-4-yl)-urea (SB265610) has been described as binding competitively with the endogenous agonist. This is in contrast to many other chemokine receptor antagonists, where the mechanism of antagonism has been described as allosteric. Experimental approach: To determine whether it displays a unique mechanism among the chemokine receptor antagonists, the mode of action of SB265610 was investigated at the CXCR2 receptor using radioligand and [35S]-GTPγS binding approaches in addition to chemotaxis of human neutrophils. Key results: In equilibrium saturation binding studies, SB265610 depressed the maximal binding of [125I]-interleukin-8 ([125I]-IL-8) without affecting the Kd. In contrast, IL-8 was unable to prevent binding of [3H]-SB265610. Kinetic binding experiments demonstrated that this was not an artefact of irreversible or slowly reversible binding. In functional experiments, SB265610 caused a rightward shift of the concentration-response curves to IL-8 and growth-related oncogene α, but also a reduction in maximal response elicited by each agonist. Fitting these data to an operational allosteric ternary complex model suggested that, once bound, SB265610 completely blocks receptor activation. SB265610 also inhibited basal [35S]-GTPγS binding in this preparation. Conclusions and implications: Taken together, these data suggest that SB265610 behaves as an allosteric inverse agonist at the CXCR2 receptor, binding at a region distinct from the agonist binding site to prevent receptor activation, possibly by interfering with G protein coupling. PMID:19422399

Technology-Use Mediation

DEFF Research Database (Denmark)

Bansler, Jørgen P.; Havn, Erling C.

2003-01-01

This study analyzes how a group of ‘mediators’ in a large, multinational company adapted a computer-mediated communication technology (a ‘virtual workspace’) to the organizational context (and vice versa) by modifying features of the technology, providing ongoing support for users, and promoting...... appropriate conventions of use. Our findings corroborate earlier research on technology-use mediation, which suggests that such mediators can exert considerable influence on how a particular technology will be established and used in an organization. However, this study also indicates that the process...... of technology-use mediation is more complex and indeterminate than earlier literature suggests. In particular, we want to draw attention to the fact that advanced computer-mediated communication technologies are equivocal and that technology-use mediation consequently requires ongoing sensemaking (Weick 1995)....

Multilevel Leadership and Organizational Effectiveness in Indian Technical Education: The Mediating Role of Communication, Power and Culture

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Gochhayat, Jyotiranjan; Giri, Vijai N.; Suar, Damodar

2017-01-01

This study provides a new conceptualization of educational leadership with a multilevel and integrative approach. It examines the impact of multilevel leadership (MLL) on the effectiveness of technical educational institutes through the mediating effects of organizational communication, bases of power and organizational culture. Data were…

In vitro pharmacological characterization of RXFP3 allosterism: an example of probe dependency.

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Lily Alvarez-Jaimes

Full Text Available Recent findings suggest that the relaxin-3 neural network may represent a new ascending arousal pathway able to modulate a range of neural circuits including those affecting circadian rhythm and sleep/wake states, spatial and emotional memory, motivation and reward, the response to stress, and feeding and metabolism. Therefore, the relaxin-3 receptor (RXFP3 is a potential therapeutic target for the treatment of various CNS diseases. Here we describe a novel selective RXFP3 receptor positive allosteric modulator (PAM, 3-[3,5-Bis(trifluoromethylphenyl]-1-(3,4-dichlorobenzyl-1-[2-(5-methoxy-1H-indol-3-ylethyl]urea (135PAM1. Calcium mobilization and cAMP accumulation assays in cell lines expressing the cloned human RXFP3 receptor show the compound does not directly activate RXFP3 receptor but increases functional responses to amidated relaxin-3 or R3/I5, a chimera of the INSL5 A chain and the Relaxin-3 B chain. 135PAM1 increases calcium mobilization in the presence of relaxin-3(NH2 and R3/I5(NH2 with pEC50 values of 6.54 (6.46 to 6.64 and 6.07 (5.94 to 6.20, respectively. In the cAMP accumulation assay, 135PAM1 inhibits the CRE response to forskolin with a pIC50 of 6.12 (5.98 to 6.27 in the presence of a probe (10 nM concentration of relaxin-3(NH2. 135PAM1 does not compete for binding with the orthosteric radioligand, [(125I] R3I5 (amide, in membranes prepared from cells expressing the cloned human RXFP3 receptor. 135PAM1 is selective for RXFP3 over RXFP4, which also responds to relaxin-3. However, when using the free acid (native form of relaxin-3 or R3/I5, 135PAM1 doesn't activate RXFP3 indicating that the compound's effect is probe dependent. Thus one can exchange the entire A-chain of the probe peptide while retaining PAM activity, but the state of the probe's c-terminus is crucial to allosteric activity of the PAM. These data demonstrate the existence of an allosteric site for modulation of this GPCR as well as the subtlety of changes in probe

A comparison of communication models of traditional and video-mediated health care delivery.

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Demiris, George; Edison, Karen; Vijaykumar, Santosh

2005-10-01

While there may be benefits that accrue to the use of telemedicine technology in patient care, such as decreased costs and improved access, it has yet to be determined how telemedicine impacts patients' ability to express themselves and accordingly, how it impacts health care providers' communication of instructions or expressions of empathy. The aim of this study was to examine the effect of telemedicine technology on communication by comparing the style and content of communication between actual (i.e., face to face) and virtual (i.e., non-face to face, telemedical) dermatology visits. The hypothesis was that there is no difference in the content and style of communication between actual and virtual visits in dermatology. Face-to-face and video-mediated dermatology sessions were observed and also audiotaped, timed and transcribed. A content analysis was performed. Average duration of a face-to-face session was 11 min (S.D. 0.08) and of a telemedical session 9 min (S.D. 0.002). Small talk occurred in 20% of all face-to-face and 29.6% of all telemedical visits. Clinical assessment occurred in all sessions. Patient education occurred in 90% of face-to-face and 78% of telemedical visits. Other themes were also identified (e.g., discussion of treatment, promotion of compliance, psychosocial issues). In 14.8% of telemedical sessions technical issues were raised. Findings indicate that communication patterns in the two modes of care delivery are comparable.

A novel strategy for selection of allosteric ribozymes yields RiboReporter™ sensors for caffeine and aspartame

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Ferguson, Alicia; Boomer, Ryan M.; Kurz, Markus; Keene, Sara C.; Diener, John L.; Keefe, Anthony D.; Wilson, Charles; Cload, Sharon T.

2004-01-01

We have utilized in vitro selection technology to develop allosteric ribozyme sensors that are specific for the small molecule analytes caffeine or aspartame. Caffeine- or aspartame-responsive ribozymes were converted into fluorescence-based RiboReporter™ sensor systems that were able to detect caffeine or aspartame in solution over a concentration range from 0.5 to 5 mM. With read-times as short as 5 min, these caffeine- or aspartame-dependent ribozymes function as highly specific and facile molecular sensors. Interestingly, successful isolation of allosteric ribozymes for the analytes described here was enabled by a novel selection strategy that incorporated elements of both modular design and activity-based selection methods typically used for generation of catalytic nucleic acids. PMID:15026535

Molecular Basis for Allosteric Inhibition of Acid-Sensing Ion Channel 1a by Ibuprofen

DEFF Research Database (Denmark)

Lynagh, Timothy; Romero-Rojo, José Luis; Lund, Camilla

2017-01-01

-clamp fluorometry. Our results show that ibuprofen is an allosteric inhibitor of ASIC1a, which binds to a crucial site in the agonist transduction pathway and causes conformational changes that oppose channel activation. Ibuprofen inhibits several ASIC subtypes, but certain ibuprofen derivatives show some...

Media Education towards peace cultures. Future professionals of the communication sector as citizens-mediators

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Eloísa NOS ALDÁS

2012-12-01

Full Text Available This paper presents a pioneering experience for Spanish University Communication degrees. It deals with the elective subject «Audiovisual Discourses and Peace Culture» offered in the fourth year of the Audiovisual Communication University Degree at Universitat Jaume I of Castellón. This learning project is focused on the proposals of peace research as a complementary and coincident research and educative project to educommunication. In this course students realize their role as citizens professionals of communication, and, therefore, their responsibility and that of their communicative acts in the configuration of society and culture. It focuses on the possibilities and consequences of their discourses as mediators in public communication scenarios to participate of the debate towards cultures for peace. The paper shares the design, development and results of this subject during 6 years as a university teaching project that can be extrapolated to other learning contexts. It is presented as well as an epistemological and methodological reflection that can be applied to all main subjects in the different communication university curricula so that students graduate being prepared both from a technical and commercial perspective but also from an educommunicative, critical, civic, social and cultural one. This text pays special attention to the audiovisual examples (films and documentaries above all used in the classes, to the ideas commented on them and to the methods for analyzing them taught from a cultural efficacy perspective and with the aim of detecting the discourse strategies of awareness communication to train citizenry in conflict transformation and solidarity.

Mutation of I696 and W697 in the TRP box of vanilloid receptor subtype I modulates allosteric channel activation.

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Gregorio-Teruel, Lucia; Valente, Pierluigi; González-Ros, José Manuel; Fernández-Ballester, Gregorio; Ferrer-Montiel, Antonio

2014-03-01

The transient receptor potential vanilloid receptor subtype I (TRPV1) channel acts as a polymodal sensory receptor gated by chemical and physical stimuli. Like other TRP channels, TRPV1 contains in its C terminus a short, conserved domain called the TRP box, which is necessary for channel gating. Substitution of two TRP box residues-I696 and W697-with Ala markedly affects TRPV1's response to all activating stimuli, which indicates that these two residues play a crucial role in channel gating. We systematically replaced I696 and W697 with 18 native l-amino acids (excluding cysteine) and evaluated the effect on voltage- and capsaicin-dependent gating. Mutation of I696 decreased channel activation by either voltage or capsaicin; furthermore, gating was only observed with substitution of hydrophobic amino acids. Substitution of W697 with any of the 18 amino acids abolished gating in response to depolarization alone, shifting the threshold to unreachable voltages, but not capsaicin-mediated gating. Moreover, vanilloid-activated responses of W697X mutants showed voltage-dependent gating along with a strong voltage-independent component. Analysis of the data using an allosteric model of activation indicates that mutation of I696 and W697 primarily affects the allosteric coupling constants of the ligand and voltage sensors to the channel pore. Together, our findings substantiate the notion that inter- and/or intrasubunit interactions at the level of the TRP box are critical for efficient coupling of stimulus sensing and gate opening. Perturbation of these interactions markedly reduces the efficacy and potency of the activating stimuli. Furthermore, our results identify these interactions as potential sites for pharmacological intervention.

Perceived Benefits and Drawbacks of Synchronous Voice-Based Computer-Mediated Communication in the Foreign Language Classroom

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Bueno Alastuey, M. C.

2011-01-01

This study explored the benefits and drawbacks of synchronous voice-based computer-mediated communication (CMC) in a blended course of English for specific purposes. Quantitative and qualitative data from two groups following the same syllabus, except for the oral component, were compared. Oral tasks were carried out face-to-face with same L1…

The Influence of Perceived Information Overload on Student Participation and Knowledge Construction in Computer-Mediated Communication

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Chen, Chun-Ying; Pedersen, Susan; Murphy, Karen L.

2012-01-01

Computer-mediated communication (CMC) has been used widely to engage learners in academic discourse for knowledge construction. Due to the features of the task environment, one of the main problems caused by the medium is information overload (IO). Yet the literature is unclear about the impact of IO on student learning. This study therefore…

Piracetam Defines a New Binding Site for Allosteric Modulators of α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptors§

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Ahmed, Ahmed H.; Oswald, Robert E.

2010-01-01

Glutamate receptors are the most prevalent excitatory neurotransmitter receptors in the vertebrate central nervous system and are important potential drug targets for cognitive enhancement and the treatment of schizophrenia. Allosteric modulators of AMPA receptors promote dimerization by binding to a dimer interface and reducing desensitization and deactivation. The pyrrolidine allosteric modulators, piracetam and aniracetam, were among the first of this class of drugs to be discovered. We have determined the structure of the ligand binding domain of the AMPA receptor subtypes GluA2 and GluA3 with piracetam and a corresponding structure of GluA3 with aniracetam. Both drugs bind to both GluA2 and GluA3 in a very similar manner, suggesting little subunit specificity. However, the binding sites for piracetam and aniracetam differ considerably. Aniracetam binds to a symmetrical site at the center of the dimer interface. Piracetam binds to multiple sites along the dimer interface with low occupation, one of which is a unique binding site for potential allosteric modulators. This new site may be of importance in the design of new allosteric regulators. PMID:20163115

Mediation of Conflicts – a Viable Solution for Surpassing Communication Barriers. President-Mediator in the Conflict between the Government and the Syndicate’s Organizations from the Education Field

OpenAIRE

Laura Maria MARUSCA

2009-01-01

The premises of this project are that approximately 90% of the conflicts in the modern society and not only, are based on poor communication. Any type of miscommunication (due to cultural, linguistic, politic or religious differences) can and will generate conflicts of various intensities going from simple quarrels to diplomatic incidents and all the way to wars. The mediator has the role to solve any existing conflict and to help repair the breaches from the communicational system between pa...

Effects of Synchronous Computer-Mediated Communication and Face-to-Face Interaction on Speaking Skill Development of Iranian EFL Learners

OpenAIRE

Hakimeh Shahrokhi Mehr; Masoud Zoghi; Nader Assadi

2013-01-01

The traditional form of teaching speaking skill has been via face-to-face (FTF) interaction in the classroom setting. Today in the computer age, the on-line forum can provide a virtual environment for differential communication. The pedagogical system benefits from such technology improvement for teaching foreign languages. This quasi-experimental research aimed at comparing the effects of two instructional strategies: synchronous computer-mediated communication (SCMC) and FTF interaction. Fo...

Divergence of allosteric effects of rapacuronium on binding and function of muscarinic receptors

Czech Academy of Sciences Publication Activity Database

Jakubík, Jan; Randáková, Alena; El-Fakahany, E. E.; Doležal, Vladimír

2009-01-01

Roč. 9, č. 15 (2009), s. 1-20 ISSN 1471-2210 R&D Projects: GA ČR GA305/09/0681; GA MŠk(CZ) LC554; GA AV ČR(CZ) IAA500110703 Institutional research plan: CEZ:AV0Z50110509 Keywords : muscarinic receptors * allosteric modulation * rapacuronium Subject RIV: ED - Physiology

Allosteric interactions between agonists and antagonists within the adenosine A2A receptor-dopamine D2 receptor heterotetramer.

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Bonaventura, Jordi; Navarro, Gemma; Casadó-Anguera, Verònica; Azdad, Karima; Rea, William; Moreno, Estefanía; Brugarolas, Marc; Mallol, Josefa; Canela, Enric I; Lluís, Carme; Cortés, Antoni; Volkow, Nora D; Schiffmann, Serge N; Ferré, Sergi; Casadó, Vicent

2015-07-07

Adenosine A2A receptor (A2AR)-dopamine D2 receptor (D2R) heteromers are key modulators of striatal neuronal function. It has been suggested that the psychostimulant effects of caffeine depend on its ability to block an allosteric modulation within the A2AR-D2R heteromer, by which adenosine decreases the affinity and intrinsic efficacy of dopamine at the D2R. We describe novel unsuspected allosteric mechanisms within the heteromer by which not only A2AR agonists, but also A2AR antagonists, decrease the affinity and intrinsic efficacy of D2R agonists and the affinity of D2R antagonists. Strikingly, these allosteric modulations disappear on agonist and antagonist coadministration. This can be explained by a model that considers A2AR-D2R heteromers as heterotetramers, constituted by A2AR and D2R homodimers, as demonstrated by experiments with bioluminescence resonance energy transfer and bimolecular fluorescence and bioluminescence complementation. As predicted by the model, high concentrations of A2AR antagonists behaved as A2AR agonists and decreased D2R function in the brain.

Enzyme activity and allosteric characteristics of gamma-irradiated solid aspartate transcarbamylase

International Nuclear Information System (INIS)

Bigler, W.N.; Tolbert, B.M.

1977-01-01

Aspartate transcarbamylase purified from E. coli was lyophilized, irradiated in vacuo with γ radiation from a cesium-137 source, redissolved in buffer under a nitrogen atmosphere, and assayed for enzyme activity. Lyophilized and redissolved enzyme had normal catalytic and allosteric kinetic characteristics. The average D 37 observed with saturating substrate, 25 mM aspartate, was 4.1 Mrad. With less than saturating substrate, 5 mM aspartate, the activity increases from zero to 1.6 Mrad and then decreases with a D 37 of 7.2 Mrad. Inclusion of 1 mM CTP, an allosteric inhibitor, in the 5 mM aspartate assays results in a more pronounced maximum in the activity curve occurring at slightly higher dose, 2.2 Mrad. Inhibitability by CTP has a D 37 of 2.3 Mrad with doses below the activity maximum. Enzyme lyophilized in the presence of 1 mM CTP has a D 37 of 2.9 Mrad. ATCase activity changes caused by irradiation of lyophylized bacteria were qualitatively like the changes observed in the detailed studies with the purified enzyme. Apparent radiation sensitivities of ATCase in lyophilized bacteria were observed to vary with the technique used to disrupt the resuspended bacteria

Defining the Structural Basis for Allosteric Product Release from E. coli Dihydrofolate Reductase Using NMR Relaxation Dispersion.

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Oyen, David; Fenwick, R Bryn; Aoto, Phillip C; Stanfield, Robyn L; Wilson, Ian A; Dyson, H Jane; Wright, Peter E

2017-08-16

The rate-determining step in the catalytic cycle of E. coli dihydrofolate reductase is tetrahydrofolate (THF) product release, which can occur via an allosteric or an intrinsic pathway. The allosteric pathway, which becomes accessible when the reduced cofactor NADPH is bound, involves transient sampling of a higher energy conformational state, greatly increasing the product dissociation rate as compared to the intrinsic pathway that obtains when NADPH is absent. Although the kinetics of this process are known, the enzyme structure and the THF product conformation in the transiently formed excited state remain elusive. Here, we use side-chain proton NMR relaxation dispersion measurements, X-ray crystallography, and structure-based chemical shift predictions to explore the structural basis of allosteric product release. In the excited state of the E:THF:NADPH product release complex, the reduced nicotinamide ring of the cofactor transiently enters the active site where it displaces the pterin ring of the THF product. The p-aminobenzoyl-l-glutamate tail of THF remains weakly bound in a widened binding cleft. Thus, through transient entry of the nicotinamide ring into the active site, the NADPH cofactor remodels the enzyme structure and the conformation of the THF to form a weakly populated excited state that is poised for rapid product release.

The role of communication inequality in mediating the impacts of socioecological and socioeconomic disparities on HIV/AIDS knowledge and risk perception.

Science.gov (United States)

Bekalu, Mesfin Awoke; Eggermont, Steven

2014-02-10

Although the link between social factors and health-related outcomes has long been widely acknowledged, the mechanisms characterizing this link are relatively less known and remain a subject of continued investigation across disciplines. In this study, drawing on the structural influence model of health communication, the hypothesis that differences in concern about and information needs on HIV/AIDS, HIV/AIDS-related media use, and perceived salience of HIV/AIDS-related information, characterized as communication inequality, can at least partially mediate the impacts of socioecological (urban vs. rural) and socioeconomic (education) disparities on inequalities in HIV/AIDS knowledge and risk perception was tested. Data were collected from a random sample of 986 urban and rural respondents in northwest Ethiopia. Structural equation modeling, using the maximum likelihood method, was used to test the mediation models. The models showed an adequate fit of the data and hence supported the hypothesis that communication inequality can at least partially explain the causal mechanism linking socioeconomic and socioecological factors with HIV/AIDS knowledge and risk perception. Both urbanity versus rurality and education were found to have significant mediated effects on HIV/AIDS knowledge (urbanity vs. rurality: β = 0.28, p = .001; education: β = 0.08, p = .001) and HIV/AIDS risk perception (urbanity vs. rurality: β = 0.30, p = .001; education: β = 0.09, p = .001). It was concluded that communication inequality might form part of the socioecologically and socioeconomically embedded processes that affect HIV/AIDS-related outcomes. The findings suggest that the media and message effects that are related to HIV/AIDS behavior change communication can be viewed from a structural perspective that moves beyond the more reductionist behavioral approaches upon which most present-day HIV/AIDS communication campaigns seem to be based.

Allosteric inhibition enhances the efficacy of ABL kinase inhibitors to target unmutated BCR-ABL and BCR-ABL-T315I

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Mian Afsar

2012-09-01

Full Text Available Abstract Background Chronic myelogenous leukemia (CML and Philadelphia chromosome-positive (Ph+ acute lymphatic leukemia (Ph + ALL are caused by the t(9;22, which fuses BCR to ABL resulting in deregulated ABL-tyrosine kinase activity. The constitutively activated BCR/ABL-kinase “escapes” the auto-inhibition mechanisms of c-ABL, such as allosteric inhibition. The ABL-kinase inhibitors (AKIs Imatinib, Nilotinib or Dasatinib, which target the ATP-binding site, are effective in Ph + leukemia. Another molecular therapy approach targeting BCR/ABL restores allosteric inhibition. Given the fact that all AKIs fail to inhibit BCR/ABL harboring the ‘gatekeeper’ mutation T315I, we investigated the effects of AKIs in combination with the allosteric inhibitor GNF2 in Ph + leukemia. Methods The efficacy of this approach on the leukemogenic potential of BCR/ABL was studied in Ba/F3 cells, primary murine bone marrow cells, and untransformed Rat-1 fibroblasts expressing BCR/ABL or BCR/ABL-T315I as well as in patient-derived long-term cultures (PDLTC from Ph + ALL-patients. Results Here, we show that GNF-2 increased the effects of AKIs on unmutated BCR/ABL. Interestingly, the combination of Dasatinib and GNF-2 overcame resistance of BCR/ABL-T315I in all models used in a synergistic manner. Conclusions Our observations establish a new approach for the molecular targeting of BCR/ABL and its resistant mutants using a combination of AKIs and allosteric inhibitors.

Partial mGlu₅ Negative Allosteric Modulators Attenuate Cocaine-Mediated Behaviors and Lack Psychotomimetic-Like Effects.

Science.gov (United States)

Gould, Robert W; Amato, Russell J; Bubser, Michael; Joffe, Max E; Nedelcovych, Michael T; Thompson, Analisa D; Nickols, Hilary H; Yuh, Johannes P; Zhan, Xiaoyan; Felts, Andrew S; Rodriguez, Alice L; Morrison, Ryan D; Byers, Frank W; Rook, Jerri M; Daniels, John S; Niswender, Colleen M; Conn, P Jeffrey; Emmitte, Kyle A; Lindsley, Craig W; Jones, Carrie K

2016-03-01

Cocaine abuse remains a public health concern for which pharmacotherapies are largely ineffective. Comorbidities between cocaine abuse, depression, and anxiety support the development of novel treatments targeting multiple symptom clusters. Selective negative allosteric modulators (NAMs) targeting the metabotropic glutamate receptor 5 (mGlu5) subtype are currently in clinical trials for the treatment of multiple neuropsychiatric disorders and have shown promise in preclinical models of substance abuse. However, complete blockade or inverse agonist activity by some full mGlu5 NAM chemotypes demonstrated adverse effects, including psychosis in humans and psychotomimetic-like effects in animals, suggesting a narrow therapeutic window. Development of partial mGlu5 NAMs, characterized by their submaximal but saturable levels of blockade, may represent a novel approach to broaden the therapeutic window. To understand potential therapeutic vs adverse effects in preclinical behavioral assays, we examined the partial mGlu5 NAMs, M-5MPEP and Br-5MPEPy, in comparison with the full mGlu5 NAM MTEP across models of addiction and psychotomimetic-like activity. M-5MPEP, Br-5MPEPy, and MTEP dose-dependently decreased cocaine self-administration and attenuated the discriminative stimulus effects of cocaine. M-5MPEP and Br-5MPEPy also demonstrated antidepressant- and anxiolytic-like activity. Dose-dependent effects of partial and full mGlu5 NAMs in these assays corresponded with increasing in vivo mGlu5 occupancy, demonstrating an orderly occupancy-to-efficacy relationship. PCP-induced hyperlocomotion was potentiated by MTEP, but not by M-5MPEP and Br-5MPEPy. Further, MTEP, but not M-5MPEP, potentiated the discriminative-stimulus effects of PCP. The present data suggest that partial mGlu5 NAM activity is sufficient to produce therapeutic effects similar to full mGlu5 NAMs, but with a broader therapeutic index.

Molecular Mechanism of Action for Allosteric Modulators and Agonists in CC-chemokine Receptor 5 (CCR5).

Science.gov (United States)

Karlshøj, Stefanie; Amarandi, Roxana Maria; Larsen, Olav; Daugvilaite, Viktorija; Steen, Anne; Brvar, Matjaž; Pui, Aurel; Frimurer, Thomas Michael; Ulven, Trond; Rosenkilde, Mette Marie

2016-12-23

The small molecule metal ion chelators bipyridine and terpyridine complexed with Zn 2+ (ZnBip and ZnTerp) act as CCR5 agonists and strong positive allosteric modulators of CCL3 binding to CCR5, weak modulators of CCL4 binding, and competitors for CCL5 binding. Here we describe their binding site using computational modeling, binding, and functional studies on WT and mutated CCR5. The metal ion Zn 2+ is anchored to the chemokine receptor-conserved Glu-283 VII:06/7.39 Both chelators interact with aromatic residues in the transmembrane receptor domain. The additional pyridine ring of ZnTerp binds deeply in the major binding pocket and, in contrast to ZnBip, interacts directly with the Trp-248 VI:13/6.48 microswitch, contributing to its 8-fold higher potency. The impact of Trp-248 was further confirmed by ZnClTerp, a chloro-substituted version of ZnTerp that showed no inherent agonism but maintained positive allosteric modulation of CCL3 binding. Despite a similar overall binding mode of all three metal ion chelator complexes, the pyridine ring of ZnClTerp blocks the conformational switch of Trp-248 required for receptor activation, thereby explaining its lack of activity. Importantly, ZnClTerp becomes agonist to the same extent as ZnTerp upon Ala mutation of Ile-116 III:16/3.40 , a residue that constrains the Trp-248 microswitch in its inactive conformation. Binding studies with 125 I-CCL3 revealed an allosteric interface between the chemokine and the small molecule binding site, including residues Tyr-37 I:07/1.39 , Trp-86 II:20/2.60 , and Phe-109 III:09/3.33 The small molecules and CCL3 approach this interface from opposite directions, with some residues being mutually exploited. This study provides new insight into the molecular mechanism of CCR5 activation and paves the way for future allosteric drugs for chemokine receptors. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Allosteric mechanism of action of the therapeutic anti-IgE antibody omalizumab.

Science.gov (United States)

Davies, Anna M; Allan, Elizabeth G; Keeble, Anthony H; Delgado, Jean; Cossins, Benjamin P; Mitropoulou, Alkistis N; Pang, Marie O Y; Ceska, Tom; Beavil, Andrew J; Craggs, Graham; Westwood, Marta; Henry, Alistair J; McDonnell, James M; Sutton, Brian J

2017-06-16

Immunoglobulin E and its interactions with receptors FcϵRI and CD23 play a central role in allergic disease. Omalizumab, a clinically approved therapeutic antibody, inhibits the interaction between IgE and FcϵRI, preventing mast cell and basophil activation, and blocks IgE binding to CD23 on B cells and antigen-presenting cells. We solved the crystal structure of the complex between an omalizumab-derived Fab and IgE-Fc, with one Fab bound to each Cϵ3 domain. Free IgE-Fc adopts an acutely bent structure, but in the complex it is only partially bent, with large-scale conformational changes in the Cϵ3 domains that inhibit the interaction with FcϵRI. CD23 binding is inhibited sterically due to overlapping binding sites on each Cϵ3 domain. Studies of omalizumab Fab binding in solution demonstrate the allosteric basis for FcϵRI inhibition and, together with the structure, reveal how omalizumab may accelerate dissociation of receptor-bound IgE from FcϵRI, exploiting the intrinsic flexibility and allosteric potential of IgE. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

The importance of source and credibility perceptions in times of crisis: crisis communication in a socially mediated era

NARCIS (Netherlands)

van Zoonen, W.; van der Meer, T.

2015-01-01

Social media are invaluable sources of information during organizational crises. Although recent research confirms this fundamental role in crisis communication, this article is aimed at deepening the understanding about the role of the source of information in this socially mediated era by

Adult Attachment and Male Aggression in Couple Relationships: The Demand-Withdraw Communication Pattern and Relationship Satisfaction as Mediators

Science.gov (United States)

Fournier, Benoit; Brassard, Audrey; Shaver, Phillip R.

2011-01-01

This study examines men's domestic aggression as a function of attachment insecurities, considering the mediating roles of the demand-withdraw communication pattern and relationship satisfaction. The sample included 55 Canadian men undergoing counseling for relationship difficulties including aggression. The men completed questionnaires assessing…

Effects of Synchronous and Asynchronous Computer-Mediated Communication (CMC) Oral Conversations on English Language Learners' Discourse Functions

Science.gov (United States)

AbuSeileek, Ali Farhan; Qatawneh, Khaleel

2013-01-01

This study aimed to explore the effects of synchronous and asynchronous computer mediated communication (CMC) oral discussions on question types and strategies used by English as a Foreign Language (EFL) learners. The participants were randomly assigned to two treatment conditions/groups; the first group used synchronous CMC, while the second…

Cysteine-rich peptides (CRPs) mediate diverse aspects of cell-cell communication in plant reproduction and development.

Science.gov (United States)

Marshall, Eleanor; Costa, Liliana M; Gutierrez-Marcos, Jose

2011-03-01

Cell-cell communication in plants is essential for the correct co-ordination of reproduction, growth, and development. Studies to dissect this mode of communication have previously focussed primarily on the action of plant hormones as mediators of intercellular signalling. In animals, peptide signalling is a well-documented intercellular communication system, however, relatively little is known about this system in plants. In recent years, numerous reports have emerged about small, secreted peptides controlling different aspects of plant reproduction. Interestingly, most of these peptides are cysteine-rich, and there is convincing evidence suggesting multiple roles for related cysteine-rich peptides (CRPs) as signalling factors in developmental patterning as well as during plant pathogen responses and symbiosis. In this review, we discuss how CRPs are emerging as key signalling factors in regulating multiple aspects of vegetative growth and reproductive development in plants.

Learning Style and Task Performance in Synchronous Computer-Mediated Communication: A Case Study of Iranian EFL Learners

Science.gov (United States)

Hedayati, Mohsen; Foomani, Elham Mohammadi

2015-01-01

The study reported here explores whether English as a foreign Language (EFL) learners' preferred ways of learning (i.e., learning styles) affect their task performance in computer-mediated communication (CMC). As Ellis (2010) points out, while the increasing use of different sorts of technology is witnessed in language learning contexts, it is…

Technology-Use Mediation

DEFF Research Database (Denmark)

Bansler, Jørgen P.; Havn, Erling C.

2004-01-01

Implementation of new computer-mediated communication (CMC) systems in organizations is a complex socio-technical endeavour, involving the mutual adaptation of technology and organization over time. Drawing on the analytic concept of sensemaking, this paper provides a theoretical perspective...... that deepens our understanding of how organizations appropriate new electronic communication media. The paper analyzes how a group of mediators in a large, multinational company adapted a new web-based CMC technology (a virtual workspace) to the local organizational context (and vice versa) by modifying...... features of the technology, providing ongoing support for users, and promoting appropriate conventions of use. We found that these mediators exerted considerable influence on how the technology was established and used in the organization. The mediators were not neutral facilitators of a well...

Content Analysis in Computer-Mediated Communication: Analyzing Models for Assessing Critical Thinking through the Lens of Social Constructivism

Science.gov (United States)

Buraphadeja, Vasa; Dawson, Kara

2008-01-01

This article reviews content analysis studies aimed to assess critical thinking in computer-mediated communication. It also discusses theories and content analysis models that encourage critical thinking skills in asynchronous learning environments and reviews theories and factors that may foster critical thinking skills and new knowledge…

VU0477573: Partial Negative Allosteric Modulator of the Subtype 5 Metabotropic Glutamate Receptor with In Vivo Efficacy.

Science.gov (United States)

Nickols, Hilary Highfield; Yuh, Joannes P; Gregory, Karen J; Morrison, Ryan D; Bates, Brittney S; Stauffer, Shaun R; Emmitte, Kyle A; Bubser, Michael; Peng, Weimin; Nedelcovych, Michael T; Thompson, Analisa; Lv, Xiaohui; Xiang, Zixiu; Daniels, J Scott; Niswender, Colleen M; Lindsley, Craig W; Jones, Carrie K; Conn, P Jeffrey

2016-01-01

Negative allosteric modulators (NAMs) of metabotropic glutamate receptor subtype 5 (mGlu5) have potential applications in the treatment of fragile X syndrome, levodopa-induced dyskinesia in Parkinson disease, Alzheimer disease, addiction, and anxiety; however, clinical and preclinical studies raise concerns that complete blockade of mGlu5 and inverse agonist activity of current mGlu5 NAMs contribute to adverse effects that limit the therapeutic use of these compounds. We report the discovery and characterization of a novel mGlu5 NAM, N,N-diethyl-5-((3-fluorophenyl)ethynyl)picolinamide (VU0477573) that binds to the same allosteric site as the prototypical mGlu5 NAM MPEP but displays weak negative cooperativity. Because of this weak cooperativity, VU0477573 acts as a "partial NAM" so that full occupancy of the MPEP site does not completely inhibit maximal effects of mGlu5 agonists on intracellular calcium mobilization, inositol phosphate (IP) accumulation, or inhibition of synaptic transmission at the hippocampal Schaffer collateral-CA1 synapse. Unlike previous mGlu5 NAMs, VU0477573 displays no inverse agonist activity assessed using measures of effects on basal [(3)H]inositol phosphate (IP) accumulation. VU0477573 acts as a full NAM when measuring effects on mGlu5-mediated extracellular signal-related kinases 1/2 phosphorylation, which may indicate functional bias. VU0477573 exhibits an excellent pharmacokinetic profile and good brain penetration in rodents and provides dose-dependent full mGlu5 occupancy in the central nervous system (CNS) with systemic administration. Interestingly, VU0477573 shows robust efficacy, comparable to the mGlu5 NAM MTEP, in models of anxiolytic activity at doses that provide full CNS occupancy of mGlu5 and demonstrate an excellent CNS occupancy-efficacy relationship. VU0477573 provides an exciting new tool to investigate the efficacy of partial NAMs in animal models. Copyright © 2015 by The American Society for Pharmacology and

The influence of multiple trials and computer-mediated communication on collaborative and individual semantic recall.

Science.gov (United States)

Hinds, Joanne M; Payne, Stephen J

2018-04-01

Collaborative inhibition is a phenomenon where collaborating groups experience a decrement in recall when interacting with others. Despite this, collaboration has been found to improve subsequent individual recall. We explore these effects in semantic recall, which is seldom studied in collaborative retrieval. We also examine "parallel CMC", a synchronous form of computer-mediated communication that has previously been found to improve collaborative recall [Hinds, J. M., & Payne, S. J. (2016). Collaborative inhibition and semantic recall: Improving collaboration through computer-mediated communication. Applied Cognitive Psychology, 30(4), 554-565]. Sixty three triads completed a semantic recall task, which involved generating words beginning with "PO" or "HE" across three recall trials, in one of three retrieval conditions: Individual-Individual-Individual (III), Face-to-face-Face-to-Face-Individual (FFI) and Parallel-Parallel-Individual (PPI). Collaborative inhibition was present across both collaborative conditions. Individual recall in Recall 3 was higher when participants had previously collaborated in comparison to recalling three times individually. There was no difference between face-to-face and parallel CMC recall, however subsidiary analyses of instance repetitions and subjective organisation highlighted differences in group members' approaches to recall in terms of organisation and attention to others' contributions. We discuss the implications of these findings in relation to retrieval strategy disruption.

Mediating Trust in Terrorism Coverage

DEFF Research Database (Denmark)

Mogensen, Kirsten

crisis. While the framework is presented in the context of television coverage of a terror-related crisis situation, it can equally be used in connection with all other forms of mediated trust. Key words: National crisis, risk communication, crisis management, television coverage, mediated trust.......Mass mediated risk communication can contribute to perceptions of threats and fear of “others” and/or to perceptions of trust in fellow citizens and society to overcome problems. This paper outlines a cross-disciplinary holistic framework for research in mediated trust building during an acute...

Mixed Media Richness and Computer-Mediated Communications

OpenAIRE

Atkins, Anthony B.

2006-01-01

Mixed richness communications occur when a participant in a conversation receives a different media or combination of media than they transmit. Mixed richness communications occur in the workplace when technical, physiological or practical limitations prevent the use of the same media on both ends of a conversation. Prior research in CMC has focused on same-richness communications, and the design guidelines that are available for same-richness communications may not be applicable to mixed-r...

Mediated awareness for intra-family communication

NARCIS (Netherlands)

Khan, V.J.

2009-01-01

The research presented in this thesis has two objectives. The first objective is to investigate the current communication practices of family members to stay in touch with each other. Based on this investigation it elicits requirements for new pervasive communication systems, called awareness

Knowledge acquisition in ecological poduct design: the effects of computer-mediated communication and elicitation method

OpenAIRE

Sauer, J.; Schramme, S.; Rüttinger, B.

2000-01-01

This article presents a study that examines multiple effects of using different means of computer-mediated communication and knowledge elicitation methods during a product design process. The experimental task involved a typical scenario in product design, in which a knowledge engineer consults two experts to generate knowledge about a design issue. Employing a 3x2 between-subjects design, three conference types (face-to-face, computer, multivedia) and two knowledge elicitation methods (struc...

A Non-Competitive Inhibitor of VCP/p97 and VPS4 Reveals Conserved Allosteric Circuits in Type I and II AAA ATPases.

Science.gov (United States)

Pöhler, Robert; Krahn, Jan H; van den Boom, Johannes; Dobrynin, Grzegorz; Kaschani, Farnusch; Eggenweiler, Hans-Michael; Zenke, Frank T; Kaiser, Markus; Meyer, Hemmo

2018-02-05

AAA ATPases have pivotal functions in diverse cellular processes essential for survival and proliferation. Revealing strategies for chemical inhibition of this class of enzymes is therefore of great interest for the development of novel chemotherapies or chemical tools. Here, we characterize the compound MSC1094308 as a reversible, allosteric inhibitor of the type II AAA ATPase human ubiquitin-directed unfoldase (VCP)/p97 and the type I AAA ATPase VPS4B. Subsequent proteomic, genetic and biochemical studies indicate that MSC1094308 binds to a previously characterized drugable hotspot of p97, thereby inhibiting the D2 ATPase activity. Our results furthermore indicate that a similar allosteric site exists in VPS4B, suggesting conserved allosteric circuits and drugable sites in both type I and II AAA ATPases. Our results may thus guide future chemical tool and drug discovery efforts for the biomedically relevant AAA ATPases. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Computer-Mediated Word-of-Mouth Communication: The Influence of Mixed Reviews on Student Perceptions of Instructors and Courses

Science.gov (United States)

Edwards, Autumn; Edwards, Chad

2013-01-01

The purpose of this experiment was to test the influence of mixed reviews appearing as computer-mediated word-of-mouth communication (WOM) on student perceptions of instructors (attractiveness and credibility) and attitudes toward learning course content (affective learning and state motivation). Using the heuristic-systematic processing model, it…

The Mediator Effect of Career Development between Personality Traits and Organizational Commitment: The Example of Sport Communication Technology Talents

Science.gov (United States)

Lo, Hung-Jen; Lin, Chun-Hung; Tung-Hsing, Lin; Tu, Peng-Fei

2014-01-01

This paper explored the relationships among career development, personality trait, and organizational commitment and examines whether career development mediates the relationship between personality trait and organizational commitment. The sample was 275 sport communication technology talents in Taiwan. The instrument included the Personality…

Aryloxyalkanoic Acids as Non-Covalent Modifiers of the Allosteric Properties of Hemoglobin

Directory of Open Access Journals (Sweden)

Abdelsattar M. Omar

2016-08-01

Full Text Available Hemoglobin (Hb modifiers that stereospecifically inhibit sickle hemoglobin polymer formation and/or allosterically increase Hb affinity for oxygen have been shown to prevent the primary pathophysiology of sickle cell disease (SCD, specifically, Hb polymerization and red blood cell sickling. Several such compounds are currently being clinically studied for the treatment of SCD. Based on the previously reported non-covalent Hb binding characteristics of substituted aryloxyalkanoic acids that exhibited antisickling properties, we designed, synthesized and evaluated 18 new compounds (KAUS II series for enhanced antisickling activities. Surprisingly, select test compounds showed no antisickling effects or promoted erythrocyte sickling. Additionally, the compounds showed no significant effect on Hb oxygen affinity (or in some cases, even decreased the affinity for oxygen. The X-ray structure of deoxygenated Hb in complex with a prototype compound, KAUS-23, revealed that the effector bound in the central water cavity of the protein, providing atomic level explanations for the observed functional and biological activities. Although the structural modification did not lead to the anticipated biological effects, the findings provide important direction for designing candidate antisickling agents, as well as a framework for novel Hb allosteric effectors that conversely, decrease the protein affinity for oxygen for potential therapeutic use for hypoxic- and/or ischemic-related diseases.

Engineering integrated digital circuits with allosteric ribozymes for scaling up molecular computation and diagnostics.

Science.gov (United States)

Penchovsky, Robert

2012-10-19

Here we describe molecular implementations of integrated digital circuits, including a three-input AND logic gate, a two-input multiplexer, and 1-to-2 decoder using allosteric ribozymes. Furthermore, we demonstrate a multiplexer-decoder circuit. The ribozymes are designed to seek-and-destroy specific RNAs with a certain length by a fully computerized procedure. The algorithm can accurately predict one base substitution that alters the ribozyme's logic function. The ability to sense the length of RNA molecules enables single ribozymes to be used as platforms for multiple interactions. These ribozymes can work as integrated circuits with the functionality of up to five logic gates. The ribozyme design is universal since the allosteric and substrate domains can be altered to sense different RNAs. In addition, the ribozymes can specifically cleave RNA molecules with triplet-repeat expansions observed in genetic disorders such as oculopharyngeal muscular dystrophy. Therefore, the designer ribozymes can be employed for scaling up computing and diagnostic networks in the fields of molecular computing and diagnostics and RNA synthetic biology.

Structural changes at the myrtenol backbone reverse its positive allosteric potential into inhibitory GABAA receptor modulation

DEFF Research Database (Denmark)

Milanos, Sinem; Kuenzel, Katharina; Gilbert, Daniel F

2017-01-01

monoterpenes, e.g. myrtenol as positive allosteric modulator at α1β2 GABAA receptors. Here, along with pharmacophore-based virtual screening studies, we demonstrate that scaffold modifications of myrtenol resulted in loss of modulatory activity. Two independent approaches, fluorescence-based compound analysis...

Using peer-mediated instruction to support communication involving a student with autism during mathematics activities: A case study.

Science.gov (United States)

Tan, Paulo; Alant, Erna

2018-01-01

This study employed an A-B singled subject design to explore the extent to which a peer-mediated intervention supported a first-grade student with autism's usage both in purpose and frequency of a speech-generating device (SGD) during mathematics activities. The intervention involved teaching a peer without a disability to encourage the student with autism to use the SGD during partnered mathematics activities. Our analysis involved visual and descriptive examination of trends and patterns over time, and comparison of means between and within phases. We found during the course of this study that (1) the student with autism's level of overall communication, which included the relevancy of these communicative behaviors, increased; (2) the student with autism's level of spontaneous communication acts increased; and (3) the peer became more independent with supporting the student with autism's communication. Implications for future research and practice are provided.

Modulation in selectivity and allosteric properties of small-molecule ligands for CC-chemokine receptors

DEFF Research Database (Denmark)

Thiele, Stefanie; Malmgaard-Clausen, Mikkel; Engel-Andreasen, Jens

2012-01-01

Among 18 human chemokine receptors, CCR1, CCR4, CCR5, and CCR8 were activated by metal ion Zn(II) or Cu(II) in complex with 2,2'-bipyridine or 1,10-phenanthroline with similar potencies (EC(50) from 3.9 to 172 μM). Besides being agonists, they acted as selective allosteric enhancers of CCL3. Thes...

The Conformational Dynamics of Cas9 Governing DNA Cleavage Are Revealed by Single-Molecule FRET.

Science.gov (United States)

Yang, Mengyi; Peng, Sijia; Sun, Ruirui; Lin, Jingdi; Wang, Nan; Chen, Chunlai

2018-01-09

Off-target binding and cleavage by Cas9 pose major challenges in its application. How the conformational dynamics of Cas9 govern its nuclease activity under on- and off-target conditions remains largely unknown. Here, using intra-molecular single-molecule fluorescence resonance energy transfer measurements, we revealed that Cas9 in apo, sgRNA-bound, and dsDNA/sgRNA-bound forms spontaneously transits among three major conformational states, mainly reflecting significant conformational mobility of the catalytic HNH domain. We also uncovered surprising long-range allosteric communication between the HNH domain and the RNA/DNA heteroduplex at the PAM-distal end to ensure correct positioning of the catalytic site, which demonstrated that a unique proofreading mechanism served as the last checkpoint before DNA cleavage. Several Cas9 residues were likely to mediate the allosteric communication and proofreading step. Modulating interactions between Cas9 and heteroduplex at the PAM-distal end by introducing mutations on these sites provides an alternative route to improve and optimize the CRISPR/Cas9 toolbox. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Social Communication Effects of Peer-Mediated Recess Intervention for Children with Autism

Science.gov (United States)

McFadden, Brandon; Kamps, Debra; Heitzman-Powell, Linda

2015-01-01

Children with ASD face enormous challenges in the area of social functioning. Research has shown that impairments in social functioning distinguish this population from both typically developing children and children with disabilities. This study incorporated several evidence-based social skills-teaching procedures (i.e., direct instruction, priming, prompting, peer-mediation, contingent reinforcement, and token economies) directly in the recess setting to increase appropriate social behaviors for four children with ASD (ages 6–8). Elements of Peer Networks and Pivotal Response Training (two types of social skills intervention packages in the literature) were included. Results showed significant increases in social communication between focus children and their peers, as well as generalization of skills to non-intervention recesses. PMID:26312064

Quality of life and adolescents' communication with their significant others (mother, father, and best friend): the mediating effect of attachment to pets.

Science.gov (United States)

Marsa-Sambola, Ferran; Williams, Joanne; Muldoon, Janine; Lawrence, Alistair; Connor, Melanie; Currie, Candace

2017-06-01

The relationship between adolescents' communication with their significant others (mother, father, and best friend) and quality of life (KIDSCREEN) was investigated in 2262 Scottish adolescent pet owners. The variable attachment to pets was also tested and assessed as a mediator of this relationship. A positive relationship between adolescents' communication with their significant other (mother, father, and best friend) and quality of life decreased when controlling for attachment to dogs. In cat owners, a positive relationship between communication with a best friend and quality of life decreased when controlling for attachment to cats. In cat and dog owners, attachment to these pets predicted higher levels of quality of life. Higher attachment to dogs and cats was explained by good best friend (IV) and attachment to pets (DV) and best friends. Mediation effects of attachment to dogs and cats might be explained in terms of the caring activities associated with these types of pets.

Computer-Mediated Communication and Majority Influence: Assessing the Impact in an Individualistic and a Collectivistic Culture

OpenAIRE

Bernard C. Y. Tan; Kwok-Kee Wei; Richard T. Watson; Danial L. Clapper; Ephraim R. McLean

1998-01-01

Strong majority influence can potentially harm organizational decisions by causing decision makers to engage in groupthink. This study examines whether and how computer-mediated communication (CMC) can reduce majority influence and thereby enhance the quality of decisions in some situations. To measure the impact of CMC on majority influence, three settings (unsupported, face-to-face CMC, and dispersed CMC) were compared. Matching laboratory experiments were carried out in an individualistic ...

Complex pharmacology of novel allosteric free fatty acid 3 receptor ligands

DEFF Research Database (Denmark)

Hudson, Brian D; Christiansen, Elisabeth; Murdoch, Hannah

2014-01-01

this series resulted in compounds completely lacking activity, acting as FFA3 PAMs, or appearing to act as FFA3-negative allosteric modulators. However, the pharmacology of this series was further complicated in that certain analogs displaying overall antagonism of FFA3 function actually appeared to generate......, considerable care must be taken to define the pharmacological characteristics of specific compounds before useful predictions of their activity and their use in defining specific roles of FFA3 in either in vitro and in vivo settings can be made....

Interlimb communication

DEFF Research Database (Denmark)

Stevenson, Andrew James Thomas

A continual coordination between the two legs is necessary for maintaining a symmetric walking pattern and adapting to changes in the external environment. Recent evidence in animals and humans suggests that spinal interneuronal circuits under supraspinal control may mediate communication between...... the lower limbs. The overall objective of the present thesis was to further investigate and elucidate neural pathways underlying interlimb communication in humans, focusing primarily on the possible interlimb connections to the biceps femoris muscle. The major aims were 1) to investigate whether interlimb...... walking (Study IV). The results of the this thesis provide new insights into the neural mechanisms underlying human interlimb communication, as well as their functional relevance to human locomotion. Although it is difficult to propose the exact neural pathways mediating interlimb reflexes...

Thermodynamics and structural analysis of positive allosteric modulation of the ionotropic glutamate receptor GluA2

DEFF Research Database (Denmark)

Krintel, Christian; Frydenvang, Karla; Olsen, Lars

2012-01-01

Positive allosteric modulators of the ionotropic glutamate receptor-2 (GluA2) are promising compounds for the treatment of cognitive disorders, e.g. Alzheimer's disease. These modulators bind within the dimer interface of the ligand-binding domain and stabilize the agonist-bound conformation slow...

Two-state dynamics of the SH3-SH2 tandem of Abl kinase and the allosteric role of the N-cap.

Science.gov (United States)

Corbi-Verge, Carles; Marinelli, Fabrizio; Zafra-Ruano, Ana; Ruiz-Sanz, Javier; Luque, Irene; Faraldo-Gómez, José D

2013-09-03

The regulation and localization of signaling enzymes is often mediated by accessory modular domains, which frequently function in tandems. The ability of these tandems to adopt multiple conformations is as important for proper regulation as the individual domain specificity. A paradigmatic example is Abl, a ubiquitous tyrosine kinase of significant pharmacological interest. SH3 and SH2 domains inhibit Abl by assembling onto the catalytic domain, allosterically clamping it in an inactive state. We investigate the dynamics of this SH3-SH2 tandem, using microsecond all-atom simulations and differential scanning calorimetry. Our results indicate that the Abl tandem is a two-state switch, alternating between the conformation observed in the structure of the autoinhibited enzyme and another configuration that is consistent with existing scattering data for an activated form. Intriguingly, we find that the latter is the most probable when the tandem is disengaged from the catalytic domain. Nevertheless, an amino acid stretch preceding the SH3 domain, the so-called N-cap, reshapes the free-energy landscape of the tandem and favors the interaction of this domain with the SH2-kinase linker, an intermediate step necessary for assembly of the autoinhibited complex. This allosteric effect arises from interactions between N-cap and the SH2 domain and SH3-SH2 connector, which involve a phosphorylation site. We also show that the SH3-SH2 connector plays a determinant role in the assembly equilibrium of Abl, because mutations thereof hinder the engagement of the SH2-kinase linker. These results provide a thermodynamic rationale for the involvement of N-cap and SH3-SH2 connector in Abl regulation and expand our understanding of the principles of modular domain organization.

Chemogenomic discovery of allosteric antagonists at the GPRC6A receptor

DEFF Research Database (Denmark)

Gloriam, David E.; Wellendorph, Petrine; Johansen, Lars Dan

2011-01-01

and pharmacological character: (1) chemogenomic lead identification through the first, to our knowledge, ligand inference between two different GPCR families, Families A and C; and (2) the discovery of the most selective GPRC6A allosteric antagonists discovered to date. The unprecedented inference of...... pharmacological activity across GPCR families provides proof-of-concept for in silico approaches against Family C targets based on Family A templates, greatly expanding the prospects of successful drug design and discovery. The antagonists were tested against a panel of seven Family A and C G protein-coupled receptors...

CavityPlus: a web server for protein cavity detection with pharmacophore modelling, allosteric site identification and covalent ligand binding ability prediction.

Science.gov (United States)

Xu, Youjun; Wang, Shiwei; Hu, Qiwan; Gao, Shuaishi; Ma, Xiaomin; Zhang, Weilin; Shen, Yihang; Chen, Fangjin; Lai, Luhua; Pei, Jianfeng

2018-05-10

CavityPlus is a web server that offers protein cavity detection and various functional analyses. Using protein three-dimensional structural information as the input, CavityPlus applies CAVITY to detect potential binding sites on the surface of a given protein structure and rank them based on ligandability and druggability scores. These potential binding sites can be further analysed using three submodules, CavPharmer, CorrSite, and CovCys. CavPharmer uses a receptor-based pharmacophore modelling program, Pocket, to automatically extract pharmacophore features within cavities. CorrSite identifies potential allosteric ligand-binding sites based on motion correlation analyses between cavities. CovCys automatically detects druggable cysteine residues, which is especially useful to identify novel binding sites for designing covalent allosteric ligands. Overall, CavityPlus provides an integrated platform for analysing comprehensive properties of protein binding cavities. Such analyses are useful for many aspects of drug design and discovery, including target selection and identification, virtual screening, de novo drug design, and allosteric and covalent-binding drug design. The CavityPlus web server is freely available at http://repharma.pku.edu.cn/cavityplus or http://www.pkumdl.cn/cavityplus.

Allosteric Inhibition of SHP2: Identification of a Potent, Selective, and Orally Efficacious Phosphatase Inhibitor

Energy Technology Data Exchange (ETDEWEB)

Fortanet, Jorge Garcia; Chen, Christine Hiu-Tung; Chen, Ying-Nan P.; Chen, Zhouliang; Deng, Zhan; Firestone, Brant; Fekkes, Peter; Fodor, Michelle; Fortin, Pascal D.; Fridrich, Cary; Grunenfelder, Denise; Ho, Samuel; Kang, Zhao B.; Karki, Rajesh; Kato, Mitsunori; Keen, Nick; LaBonte, Laura R.; Larrow, Jay; Lenoir, Francois; Liu, Gang; Liu, Shumei; Lombardo, Franco; Majumdar, Dyuti; Meyer, Matthew J.; Palermo, Mark; Perez, Lawrence; Pu, Minying; Ramsey, Timothy; Sellers, William R.; Shultz, Michael D.; Stams, Travis; Towler, Christopher; Wang, Ping; Williams, Sarah L.; Zhang, Ji-Hu; LaMarche, Matthew J. (Novartis)

2016-09-08

SHP2 is a nonreceptor protein tyrosine phosphatase (PTP) encoded by the PTPN11 gene involved in cell growth and differentiation via the MAPK signaling pathway. SHP2 also purportedly plays an important role in the programmed cell death pathway (PD-1/PD-L1). Because it is an oncoprotein associated with multiple cancer-related diseases, as well as a potential immunomodulator, controlling SHP2 activity is of significant therapeutic interest. Recently in our laboratories, a small molecule inhibitor of SHP2 was identified as an allosteric modulator that stabilizes the autoinhibited conformation of SHP2. A high throughput screen was performed to identify progressable chemical matter, and X-ray crystallography revealed the location of binding in a previously undisclosed allosteric binding pocket. Structure-based drug design was employed to optimize for SHP2 inhibition, and several new protein–ligand interactions were characterized. These studies culminated in the discovery of 6-(4-amino-4-methylpiperidin-1-yl)-3-(2,3-dichlorophenyl)pyrazin-2-amine (SHP099, 1), a potent, selective, orally bioavailable, and efficacious SHP2 inhibitor.

The therapeutic potential of allosteric ligands for free fatty acid sensitive GPCRs

DEFF Research Database (Denmark)

Hudson, Brian D; Ulven, Trond; Milligan, Graeme

2013-01-01

G protein coupled receptors (GPCRs) are the most historically successful therapeutic targets. Despite this success there are many important aspects of GPCR pharmacology and function that have yet to be exploited to their full therapeutic potential. One in particular that has been gaining attention...... safety, more physiologically appropriate responses, better target selectivity, and reduced likelihood of desensitisation and tachyphylaxis. Despite these advantages, the development of allosteric ligands is often difficult from a medicinal chemistry standpoint due to the more complex challenge...

A transwell assay that excludes exosomes for assessment of tunneling nanotube-mediated intercellular communication.

Science.gov (United States)

Thayanithy, Venugopal; O'Hare, Patrick; Wong, Phillip; Zhao, Xianda; Steer, Clifford J; Subramanian, Subbaya; Lou, Emil

2017-11-13

Tunneling nanotubes (TNTs) are naturally-occurring filamentous actin-based membranous extensions that form across a wide spectrum of mammalian cell types to facilitate long-range intercellular communication. Valid assays are needed to accurately assess the downstream effects of TNT-mediated transfer of cellular signals in vitro. We recently reported a modified transwell assay system designed to test the effects of intercellular transfer of a therapeutic oncolytic virus, and viral-activated drugs, between cells via TNTs. The objective of the current study was to demonstrate validation of this in vitro approach as a new method for effectively excluding diffusible forms of long- and close-range intercellular transfer of intracytoplasmic cargo, including exosomes/microvesicles and gap junctions in order to isolate TNT-selective cell communication. We designed several steps to effectively reduce or eliminate diffusion and long-range transfer via these extracellular vesicles, and used Nanoparticle Tracking Analysis to quantify exosomes following implementation of these steps. The experimental approach outlined here effectively reduced exosome trafficking by >95%; further use of heparin to block exosome uptake by putative recipient cells further impeded transfer of these extracellular vesicles. This validated assay incorporates several steps that can be taken to quantifiably control for extracellular vesicles in order to perform studies focused on TNT-selective communication.

Two-state dynamics of the SH3–SH2 tandem of Abl kinase and the allosteric role of the N-cap

Science.gov (United States)

Corbi-Verge, Carles; Marinelli, Fabrizio; Zafra-Ruano, Ana; Ruiz-Sanz, Javier; Luque, Irene; Faraldo-Gómez, José D.

2013-01-01

The regulation and localization of signaling enzymes is often mediated by accessory modular domains, which frequently function in tandems. The ability of these tandems to adopt multiple conformations is as important for proper regulation as the individual domain specificity. A paradigmatic example is Abl, a ubiquitous tyrosine kinase of significant pharmacological interest. SH3 and SH2 domains inhibit Abl by assembling onto the catalytic domain, allosterically clamping it in an inactive state. We investigate the dynamics of this SH3–SH2 tandem, using microsecond all-atom simulations and differential scanning calorimetry. Our results indicate that the Abl tandem is a two-state switch, alternating between the conformation observed in the structure of the autoinhibited enzyme and another configuration that is consistent with existing scattering data for an activated form. Intriguingly, we find that the latter is the most probable when the tandem is disengaged from the catalytic domain. Nevertheless, an amino acid stretch preceding the SH3 domain, the so-called N-cap, reshapes the free-energy landscape of the tandem and favors the interaction of this domain with the SH2-kinase linker, an intermediate step necessary for assembly of the autoinhibited complex. This allosteric effect arises from interactions between N-cap and the SH2 domain and SH3–SH2 connector, which involve a phosphorylation site. We also show that the SH3–SH2 connector plays a determinant role in the assembly equilibrium of Abl, because mutations thereof hinder the engagement of the SH2-kinase linker. These results provide a thermodynamic rationale for the involvement of N-cap and SH3–SH2 connector in Abl regulation and expand our understanding of the principles of modular domain organization. PMID:23959873

Determinants of positive cooperativity between strychnine-like allosteric modulators and N-methylscopolamine at muscarinic receptors

Czech Academy of Sciences Publication Activity Database

Jakubík, Jan; Doležal, Vladimír

2006-01-01

Roč. 30, č. 1-2 (2006), s. 111-112 ISSN 0895-8696 R&D Projects: GA ČR(CZ) GA305/05/0452; GA MŠk(CZ) LC554 Institutional research plan: CEZ:AV0Z50110509 Keywords : muscarinic receptors * strychnine -like allosteric modulators * cooperativity Subject RIV: ED - Physiology Impact factor: 2.965, year: 2006

A conformational switch high-throughput screening assay and allosteric inhibition of the flavivirus NS2B-NS3 protease.

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Matthew Brecher

2017-05-01

Full Text Available The flavivirus genome encodes a single polyprotein precursor requiring multiple cleavages by host and viral proteases in order to produce the individual proteins that constitute an infectious virion. Previous studies have revealed that the NS2B cofactor of the viral NS2B-NS3 heterocomplex protease displays a conformational dynamic between active and inactive states. Here, we developed a conformational switch assay based on split luciferase complementation (SLC to monitor the conformational change of NS2B and to characterize candidate allosteric inhibitors. Binding of an active-site inhibitor to the protease resulted in a conformational change of NS2B and led to significant SLC enhancement. Mutagenesis of key residues at an allosteric site abolished this induced conformational change and SLC enhancement. We also performed a virtual screen of NCI library compounds to identify allosteric inhibitors, followed by in vitro biochemical screening of the resultant candidates. Only three of these compounds, NSC135618, 260594, and 146771, significantly inhibited the protease of Dengue virus 2 (DENV2 in vitro, with IC50 values of 1.8 μM, 11.4 μM, and 4.8 μM, respectively. Among the three compounds, only NSC135618 significantly suppressed the SLC enhancement triggered by binding of active-site inhibitor in a dose-dependent manner, indicating that it inhibits the conformational change of NS2B. Results from virus titer reduction assays revealed that NSC135618 is a broad spectrum flavivirus protease inhibitor, and can significantly reduce titers of DENV2, Zika virus (ZIKV, West Nile virus (WNV, and Yellow fever virus (YFV on A549 cells in vivo, with EC50 values in low micromolar range. In contrast, the cytotoxicity of NSC135618 is only moderate with CC50 of 48.8 μM on A549 cells. Moreover, NSC135618 inhibited ZIKV in human placental and neural progenitor cells relevant to ZIKV pathogenesis. Results from binding, kinetics, Western blot, mass spectrometry and

Molecular modeling study on the allosteric inhibition mechanism of HIV-1 integrase by LEDGF/p75 binding site inhibitors.

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Weiwei Xue

Full Text Available HIV-1 integrase (IN is essential for the integration of viral DNA into the host genome and an attractive therapeutic target for developing antiretroviral inhibitors. LEDGINs are a class of allosteric inhibitors targeting LEDGF/p75 binding site of HIV-1 IN. Yet, the detailed binding mode and allosteric inhibition mechanism of LEDGINs to HIV-1 IN is only partially understood, which hinders the structure-based design of more potent anti-HIV agents. A molecular modeling study combining molecular docking, molecular dynamics simulation, and binding free energy calculation were performed to investigate the interaction details of HIV-1 IN catalytic core domain (CCD with two recently discovered LEDGINs BI-1001 and CX14442, as well as the LEDGF/p75 protein. Simulation results demonstrated the hydrophobic domain of BI-1001 and CX14442 engages one subunit of HIV-1 IN CCD dimer through hydrophobic interactions, and the hydrophilic group forms hydrogen bonds with HIV-1 IN CCD residues from other subunit. CX14442 has a larger tert-butyl group than the methyl of BI-1001, and forms better interactions with the highly hydrophobic binding pocket of HIV-1 IN CCD dimer interface, which can explain the stronger affinity of CX14442 than BI-1001. Analysis of the binding mode of LEDGF/p75 with HIV-1 IN CCD reveals that the LEDGF/p75 integrase binding domain residues Ile365, Asp366, Phe406 and Val408 have significant contributions to the binding of the LEDGF/p75 to HIV1-IN. Remarkably, we found that binding of BI-1001 and CX14442 to HIV-1 IN CCD induced the structural rearrangements of the 140 s loop and oration displacements of the side chains of the three conserved catalytic residues Asp64, Asp116, and Glu152 located at the active site. These results we obtained will be valuable not only for understanding the allosteric inhibition mechanism of LEDGINs but also for the rational design of allosteric inhibitors of HIV-1 IN targeting LEDGF/p75 binding site.

Adaptive response and genomic instability: allosteric response of genome to negative impact

International Nuclear Information System (INIS)

Sasaki, Masao S.

2010-01-01

Currently, there is an upsurge concern on the unique response of living cells to low dose ionizing radiation for its inconformity to the existing paradigm of the biological action of radiation and its impact on the current understanding of risk evaluation of health effect of radiation in our workplace and environment. For the allosteric response to have significance, the cells must have an excellent sensing mechanism to discriminate tolerable and intolerable signals. In a series of experiments with mammalian, including human, cells, we demonstrated a novel sensing and signaling mechanism in the low-dose irradiated cells that was mediated by a PKCα-p3BMAPK-PLCδ1 feedback regulatory loop. Upon irradiation, PKCα is immediately activated, which in turn activate p38MAPK. The activation of p38MAPK is feedbacked to the activation of PKCα via PLCδ1, which catalyzes the hydrolysis of PtdInsP2 to generate PKCα-directed second messengers DAG and lnsP3. At low doses, the PKCα and p38MAPK continue to be activated for long time through this feedback loop, but when the cells encounter the high dose (>10 cGy or equivalent), the feedback loop is immediately comes to shutdown by deprivation of PKCα protein, known as down-regulation of PKC signaling. Thus, PKCα plays a key role in the long lasting nature of adaptive response to low doses and a binary switch to the genomic instability by too much signals. Tumor suppressor protein, p53, is a downstream effecter

The Influence of Computer-Mediated Word-of-Mouth Communication on Student Perceptions of Instructors and Attitudes toward Learning Course Content

Science.gov (United States)

Edwards, Chad; Edwards, Autumn; Qing, Qingmei; Wahl, Shawn T.

2007-01-01

The purpose of this study was to experimentally test the influence of computer-mediated word-of-mouth communication (WOM) on student perceptions of instructors (attractiveness and credibility) and on student attitudes toward learning course content (affective learning and state motivation). It was hypothesized that students who receive positive…

The Low-Affinity Binding of Second Generation Radiotracers Targeting TSPO is Associated with a Unique Allosteric Binding Site

Czech Academy of Sciences Publication Activity Database

Rojas, C.; Stathis, M.; Coughlin, J. M.; Pomper, M.; Slusher, Barbara S.

2018-01-01

Roč. 13, č. 1 (2018), s. 1-5 ISSN 1557-1890 Institutional support: RVO:61388963 Keywords : translocator protein 18KDa (TSPO) * allosteric modulation * residence time Subject RIV: CC - Organic Chemistry OBOR OECD: Organic chemistry Impact factor: 3.339, year: 2016

THE ROLE OF OFFLINE METALANGUAGE TALK IN ASYNCHRONOUS COMPUTER-MEDIATED COMMUNICATION

Directory of Open Access Journals (Sweden)

Keiko Kitade

2008-02-01

Full Text Available In order to demonstrate how learners utilize the text-based asynchronous attributes of the Bulletin Board System, this study explored Japanese-as-a-second-language learners' metalanguage episodes (Swain & Lapkin, 1995, 1998 in offline verbal peer speech and online asynchronous discussions with their Japanese key pals. The findings suggest the crucial role of offline collaborative dialogue, the interactional modes in which the episodes occur, and the unique discourse structure of metalanguage episodes concerning online and offline interactions. A high score on the posttest also suggests the high retention of linguistic knowledge constructed through offline peer dialogue. In the offline mode, the learners were able to collaboratively construct knowledge with peers in the stipulated time, while simultaneously focusing on task content in the online interaction. The retrospective interviews and questionnaires reveal the factors that could affect the benefits of the asynchronous computer-mediated communication medium for language learning.

Role of Self-Directed Learning in Communication Competence and Self-Efficacy.

Science.gov (United States)

Song, Youngshin; Yun, Soon Young; Kim, Sun-Ae; Ahn, Eun-Kyong; Jung, Mi Sook

2015-10-01

Although effective self-directed learning (SDL) has been shown to improve clinical performance, little is known about its role between communication competence and communication self-efficacy in nursing students. This study aimed to identify whether SDL mediates the relationship between communication competence and communication self-efficacy. A cross-sectional survey was conducted with a sample of 213 nursing students taking a basic fundamentals of nursing course. A path diagram, using structural equation modeling, was used to estimate the direct and indirect effects of communication competence on communication self-efficacy, controlling for SDL as a mediator. A structural equation model confirmed direct and indirect effects of communication competence on communication self-efficacy when SDL was controlled as a mediator. An appropriate fit to the data was identified in this mediation model of SDL. For enhancing self-efficacy regarding communication skill, the specified SDL program based on the level of communication competence will yield more effective results. Copyright 2015, SLACK Incorporated.

Identification of halosalicylamide derivatives as a novel class of allosteric inhibitors of HCV NS5B polymerase.

Science.gov (United States)

Liu, Yaya; Donner, Pamela L; Pratt, John K; Jiang, Wen W; Ng, Teresa; Gracias, Vijaya; Baumeister, Steve; Wiedeman, Paul E; Traphagen, Linda; Warrior, Usha; Maring, Clarence; Kati, Warren M; Djuric, Stevan W; Molla, Akhteruzzaman

2008-06-01

Halosalicylamide derivatives were identified from high-throughput screening as potent inhibitors of HCV NS5B polymerase. The subsequent structure and activity relationship revealed the absolute requirement of the salicylamide moiety for optimum activity. Methylation of either the hydroxyl group or the amide group of the salicylamide moiety abolished the activity while the substitutions on both phenyl rings are acceptable. The halosalicylamide derivatives were shown to be non-competitive with respect to elongation nucleotide and demonstrated broad genotype activity against genotype 1-3 HCV NS5B polymerases. Inhibitor competition studies indicated an additive binding mode to the initiation pocket that is occupied by the thiadiazine class of compounds and an additive binding mode to the elongation pocket that is occupied by diketoacids, but a mutually exclusive binding mode with respect to the allosteric thumb pocket that is occupied by the benzimidazole class of inhibitors. Therefore, halosalicylamides represent a novel class of allosteric inhibitors of HCV NS5B polymerase.

Effective Communication Modes in Multilingual Encounters: Comparing Alternatives in Computer Mediated Communication (CMC)

Science.gov (United States)

van Mulken, Margot; Hendriks, Berna

2017-01-01

This paper reports on an experimental study investigating alternative communication modes to English as a Lingua Franca. The purpose was to examine the effectiveness of different modes of communication and to gain insight in communication strategies used by interlocutors to solve referential conflicts. Findings show that ELF may not necessarily be…

Handbook of Technical Communication

OpenAIRE

Mehler , Alexander; Romary , Laurent; Gibbon , Dafydd

2012-01-01

International audience; The handbook "Technical Communication" brings together a variety of topics which range from the role of technical media in human communication to the linguistic, multimodal enhancement of present-day technologies. It covers the area of computer-mediated text, voice and multimedia communication as well as of technical documentation. In doing so, the handbook takes professional and private communication into account. Special emphasis is put on technical communication bas...

Conformational control of the binding of the transactivation domain of the MLL protein and c-Myb to the KIX domain of CREB.

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Elif Nihal Korkmaz

Full Text Available The KIX domain of CBP is a transcriptional coactivator. Concomitant binding to the activation domain of proto-oncogene protein c-Myb and the transactivation domain of the trithorax group protein mixed lineage leukemia (MLL transcription factor lead to the biologically active ternary MLL∶KIX∶c-Myb complex which plays a role in Pol II-mediated transcription. The binding of the activation domain of MLL to KIX enhances c-Myb binding. Here we carried out molecular dynamics (MD simulations for the MLL∶KIX∶c-Myb ternary complex, its binary components and KIX with the goal of providing a mechanistic explanation for the experimental observations. The dynamic behavior revealed that the MLL binding site is allosterically coupled to the c-Myb binding site. MLL binding redistributes the conformational ensemble of KIX, leading to higher populations of states which favor c-Myb binding. The key element in the allosteric communication pathways is the KIX loop, which acts as a control mechanism to enhance subsequent binding events. We tested this conclusion by in silico mutations of loop residues in the KIX∶MLL complex and by comparing wild type and mutant dynamics through MD simulations. The loop assumed MLL binding conformation similar to that observed in the KIX∶c-Myb state which disfavors the allosteric network. The coupling with c-Myb binding site faded, abolishing the positive cooperativity observed in the presence of MLL. Our major conclusion is that by eliciting a loop-mediated allosteric switch between the different states following the binding events, transcriptional activation can be regulated. The KIX system presents an example how nature makes use of conformational control in higher level regulation of transcriptional activity and thus cellular events.

Investigating the effect of nurse-team communication on nurse turnover: relationships among communication processes, identification, and intent to leave.

Science.gov (United States)

Apker, Julie; Propp, Kathleen M; Ford, Wendy S Zabava

2009-03-01

Enhanced team communication may strengthen nurses' attachment to their organizations and teams and improve nurse retention. This study examines the relationships among nurse-team communication, identification (organizational and team), and intent to leave. Hospital nurses (N = 201) completed surveys measuring 3 nurse-team communication processes: promoting team synergy, ensuring quality decisions, and individualizing communication. Hierarchical regression analyses revealed that promoting team synergy was a significant predictor of intent to leave, whereas ensuring quality decisions and individualizing communication did not account for significant additional variance in intent to leave. Separate analyses showed that the relationship between promoting team synergy and intent to leave was partially mediated by team identification or by organizational identification. Further analyses were conducted on the 7 communication practices for promoting team synergy. Mentoring emerged as the only significant predictor of intent to leave; however, its relationship to intent to leave was fully mediated by organizational identification or partially mediated by team identification. Pragmatic suggestions are offered to improve nurse identification and reduce turnover.

Overlapping binding site for the endogenous agonist, small-molecule agonists, and ago-allosteric modulators on the ghrelin receptor

DEFF Research Database (Denmark)

Holst, Birgitte; Frimurer, Thomas M; Mokrosinski, Jacek

2008-01-01

A library of robust ghrelin receptor mutants with single substitutions at 22 positions in the main ligand-binding pocket was employed to map binding sites for six different agonists: two peptides (the 28-amino-acid octanoylated endogenous ligand ghrelin and the hexapeptide growth hormone......, and PheVI:23 on the opposing face of transmembrane domain (TM) VI. Each of the agonists was also affected selectively by specific mutations. The mutational map of the ability of L-692,429 and GHRP-6 to act as allosteric modulators by increasing ghrelin's maximal efficacy overlapped with the common....... It is concluded that although each of the ligands in addition exploits other parts of the receptor, a large, common binding site for both small-molecule agonists--including ago-allosteric modulators--and the endogenous agonist is found on the opposing faces of TM-III and -VI of the ghrelin receptor....

In search of allosteric modulators of a7-nAChR by solvent density guided virtual screening.

Science.gov (United States)

Dey, Raja; Chen, Lin

2011-04-01

Nicotinic acetylcholine receptors (nAChR) are pentameric ligand gated ion channels whose activity can be modulated by endogenous neurotransmitters as well as by synthetic ligands that bind the same or distinct sites from the natural ligand. The subtype of α7 nAChR has been considered as a potenial therapeutic target for Alzheimer's disease, schizophrenia and other neurological and psychiatric disorders. Here we have developed a homology model of α7 nAChR based on two high resolution crystal structures with Brookhaven Protein Data Bank (PDB) codes 2QC1 and 2WN9 for threading on one monomer and then for building a pentamer, respectively. A number of small molecule binding sites are identified using Pocket Finder (J. An, M. Tortov, and R. Abagyan, Molecular & Cellular Proteomics, 4.6, 752-761 (2005)) of Internal Coordinate Mechanics (ICM). Remarkably, these computer-identified sites match perfectly with ordered solvent densities found in the high-resolution crystal structure of α1 nAChR, suggesting that the surface cavities in the α7 nAChR model are likely binding sites of small molecules. A high throughput virtual screening by flexible ligand docking of 5008 small molecule compounds was performed at three potential allosteric modulator (AM) binding sites of α7 nAChR using Molsoft ICM software (R. Abagyan, M. Tortov and D. Kuznetsov, J Comput Chem 15, 488-506, (1994)). Some experimentally verified allosteric modulators of α7 like CCMI comp-6, LY 7082101, 5-HI, TQS, PNU-120596, genistein, and NS-1738 ranked among top 100 compounds, while the rest of the compounds in the list could guide further search for new allosteric modulators.

Enhancing NMDA Receptor Function: Recent Progress on Allosteric Modulators

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Lulu Yao

2017-01-01

Full Text Available The N-methyl-D-aspartate receptors (NMDARs are subtype glutamate receptors that play important roles in excitatory neurotransmission and synaptic plasticity. Their hypo- or hyperactivation are proposed to contribute to the genesis or progression of various brain diseases, including stroke, schizophrenia, depression, and Alzheimer’s disease. Past efforts in targeting NMDARs for therapeutic intervention have largely been on inhibitors of NMDARs. In light of the discovery of NMDAR hypofunction in psychiatric disorders and perhaps Alzheimer’s disease, efforts in boosting NMDAR activity/functions have surged in recent years. In this review, we will focus on enhancing NMDAR functions, especially on the recent progress in the generation of subunit-selective, allosteric positive modulators (PAMs of NMDARs. We shall also discuss the usefulness of these newly developed NMDAR-PAMs.

Complex Mediation

DEFF Research Database (Denmark)

Bødker, Susanne; Andersen, Peter Bøgh

2005-01-01

This article has its starting point in a large number of empirical findings regarding computer-mediated work. These empirical findings have challenged our understanding of the role of mediation in such work; on the one hand as an aspect of communication and cooperation at work and on the other hand...... as an aspect of human engagement with instruments of work. On the basis of previous work in activity-theoretical and semiotic human—computer interaction, we propose a model to encompass both of these aspects. In a dialogue with our empirical findings we move on to propose a number of types of mediation...... that have helped to enrich our understanding of mediated work and the design of computer mediation for such work....

mGluR5 Positive Allosteric Modulation Enhances Extinction Learning Following Cocaine Self-Administration

OpenAIRE

Cleva, Richard M.; Hicks, Megan P.; Gass, Justin T.; Wischerath, Kelly C.; Plasters, Elizabeth T.; Widholm, John J.; Olive, M. Foster

2011-01-01

Extinction of classically and instrumentally conditioned behaviors, such as conditioned fear and drug-seeking behavior, is a process of active learning, and recent studies indicate that potentiation of glutamatergic transmission facilitates extinction learning. In this study we investigated the effects of the type 5 metabotropic glutamate receptors (mGluR5) positive allosteric modulator 3-cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl)benzamide (CDPPB) on the extinction of cocaine-seeking behavior in ...

Role of allosteric switch residue histidine 195 in maintaining active-site asymmetry in presynaptic filaments of bacteriophage T4 UvsX recombinase.

Science.gov (United States)

Farb, Joshua N; Morrical, Scott W

2009-01-16

Recombinases of the highly conserved RecA/Rad51 family play central roles in homologous recombination and DNA double-stranded break repair. RecA/Rad51 enzymes form presynaptic filaments on single-stranded DNA (ssDNA) that are allosterically activated to catalyze ATPase and DNA strand-exchange reactions. Information is conveyed between DNA- and ATP-binding sites, in part, by a highly conserved glutamine residue (Gln194 in Escherichia coli RecA) that acts as an allosteric switch. The T4 UvsX protein is a divergent RecA ortholog and contains histidine (His195) in place of glutamine at the allosteric switch position. UvsX and RecA catalyze similar strand-exchange reactions, but differ in other properties. UvsX produces both ADP and AMP as products of its ssDNA-dependent ATPase activity--a property that is unique among characterized recombinases. Details of the kinetics of ssDNA-dependent ATP hydrolysis reactions indicate that UvsX-ssDNA presynaptic filaments are asymmetric and contain two classes of ATPase active sites: one that generates ADP, and another that generates AMP. Active-site asymmetry is reduced by mutations at the His195 position, since UvsX-H195Q and UvsX-H195A mutants both exhibit stronger ssDNA-dependent ATPase activity, with lower cooperativity and markedly higher ADP/AMP product ratios, than wild-type UvsX. Reduced active-site asymmetry correlates strongly with reduced ssDNA-binding affinity and DNA strand-exchange activity in both H195Q and H195A mutants. These and other results support a model in which allosteric switch residue His195 controls the formation of an asymmetric conformation of UvsX-ssDNA filaments that is active in DNA strand exchange. The implications of our findings for UvsX recombination functions, and for RecA functions in general, are discussed.

A key agonist-induced conformational change in the cannabinoid receptor CB1 is blocked by the allosteric ligand Org 27569.

Science.gov (United States)

Fay, Jonathan F; Farrens, David L

2012-09-28

Allosteric ligands that modulate how G protein-coupled receptors respond to traditional orthosteric drugs are an exciting and rapidly expanding field of pharmacology. An allosteric ligand for the cannabinoid receptor CB1, Org 27569, exhibits an intriguing effect; it increases agonist binding, yet blocks agonist-induced CB1 signaling. Here we explored the mechanism behind this behavior, using a site-directed fluorescence labeling approach. Our results show that Org 27569 blocks conformational changes in CB1 that accompany G protein binding and/or activation, and thus inhibit formation of a fully active CB1 structure. The underlying mechanism behind this behavior is that simultaneous binding of Org 27569 produces a unique agonist-bound conformation, one that may resemble an intermediate structure formed on the pathway to full receptor activation.

Media Differences in Communication

NARCIS (Netherlands)

Raine, Roxanne B.; Raine, Roxanne B.; Esposito, A.; Campbell, N.; Vogel, C.; Hussain, A.; Nijholt, Antinus

2010-01-01

With the ever-growing ubiquity of computer-mediated communication, the application of language research to computer-mediated environments becomes increasingly relevant. How do overhearer effects, discourse markers, differences for monologues and dialogues, and other verbal findings transmute in the

Motivations for Social Media Use and Impact on Political Participation in China: A Cognitive and Communication Mediation Approach.

Science.gov (United States)

Chen, Zhuo; Chan, Michael

2017-02-01

Integrating uses and gratifications theory and the cognitive/communication mediation model: this study examines Chinese students' use of social media and subsequent impact on political participation. An integrative framework is proposed where media use, political expression, and political cognitions (efficacy and knowledge) play important mediating roles between audience motivations and participation. Structural equation analyses showed support for the integrated model. Guidance and social utility motivations exhibited different indirect effects on online and offline participation through social media news, discussion, and political efficacy. Entertainment motivations exhibited no direct or indirect effects. Contrary to expectations and previous literature, surveillance motivations exhibited negative direct and indirect effects on offline participation, which may be attributed to the particular Chinese social and political context. Implications of the findings are discussed.

Heterotypic contact reveals a COX-2-mediated suppression of osteoblast differentiation by endothelial cells: A negative modulatory role for prostanoids in VEGF-mediated cell: cell communication?

International Nuclear Information System (INIS)

Clarkin, Claire E.; Garonna, Elena; Pitsillides, Andrew A.; Wheeler-Jones, Caroline P.D.

2008-01-01

In bone, angiogenesis must be initiated appropriately, but limited once remodelling or repair is complete. Our recent findings have supported a role for prostaglandins (PG), known modulators of osteoblast (OB) and endothelial cell (EC) behaviour, in facilitating VEGF-mediated paracrine communication from OBs to 'remotely located' ECs, but the mechanism(s) regulating OB:EC crosstalk when these cells are closely opposed are undefined. In this study we have examined: (i) the effects of exogenous PGE 2 on VEGF-driven events in ECs, and (ii) the role of endogenous COX-2-derived prostanoids in mediating communication between intimately opposed OBs and ECs in direct contact. Exposure of ECs to PGE 2 increased ERK1/2 phosphorylation, COX-2 induction, 6-keto-PGF 1α release and EC proliferation. In contrast, PGE 2 attenuated VEGF 165 -induced VEGFR2/Flk1 phosphorylation, ERK1/2 activation and proliferation of ECs, suggesting that exogenous PGE 2 restricts the actions of VEGF. However, the COX-2-selective inhibitor, NS398, also attenuated VEGF-induced proliferation, implying a distinct role for endogenous COX-2 activity in regulating EC behaviour. To examine the effect of OB:EC proximity and the role of COX-2 products further, we used a confrontational co-culture model. These studies showed that COX-2 blockade with NS398 enhanced EC-dependent increases in OB differentiation, that this effect was reversed by exogenous PGH 2 (immediate COX-2 product), and that exogenous VEGF did not influence EC-dependent OB differentiation under these conditions. Our findings indicate that locally produced prostanoids may serve distinct roles depending on OB:EC proximity and negatively modulate VEGF-mediated changes in EC behaviour when these cells are closely opposed to control angiogenesis during bone (re)modelling

Fashion, Mediations & Method Assemblages

DEFF Research Database (Denmark)

Sommerlund, Julie; Jespersen, Astrid Pernille

of handling multiple, fluid realities with multiple, fluid methods. Empirically, the paper works with mediation in fashion - that is efforts the active shaping of relations between producer and consumer through communication, marketing and PR. Fashion mediation is by no means simple, but organise complex...

Dynamic Allostery Mediated by a Conserved Tryptophan in the Tec Family Kinases.

Directory of Open Access Journals (Sweden)

Nikita Chopra

2016-03-01

Full Text Available Bruton's tyrosine kinase (Btk is a Tec family non-receptor tyrosine kinase that plays a critical role in immune signaling and is associated with the immunological disorder X-linked agammaglobulinemia (XLA. Our previous findings showed that the Tec kinases are allosterically activated by the adjacent N-terminal linker. A single tryptophan residue in the N-terminal 17-residue linker mediates allosteric activation, and its mutation to alanine leads to the complete loss of activity. Guided by hydrogen/deuterium exchange mass spectrometry results, we have employed Molecular Dynamics simulations, Principal Component Analysis, Community Analysis and measures of node centrality to understand the details of how a single tryptophan mediates allostery in Btk. A specific tryptophan side chain rotamer promotes the functional dynamic allostery by inducing coordinated motions that spread across the kinase domain. Either a shift in the rotamer population, or a loss of the tryptophan side chain by mutation, drastically changes the coordinated motions and dynamically isolates catalytically important regions of the kinase domain. This work also identifies a new set of residues in the Btk kinase domain with high node centrality values indicating their importance in transmission of dynamics essential for kinase activation. Structurally, these node residues appear in both lobes of the kinase domain. In the N-lobe, high centrality residues wrap around the ATP binding pocket connecting previously described Catalytic-spine residues. In the C-lobe, two high centrality node residues connect the base of the R- and C-spines on the αF-helix. We suggest that the bridging residues that connect the catalytic and regulatory architecture within the kinase domain may be a crucial element in transmitting information about regulatory spine assembly to the catalytic machinery of the catalytic spine and active site.

Meaningful mediation analysis : Plausible causal inference and informative communication

NARCIS (Netherlands)

Pieters, Rik

2017-01-01

Statistical mediation analysis has become the technique of choice in consumer research to make causal inferences about the influence of a treatment on an outcome via one or more mediators. This tutorial aims to strengthen two weak links that impede statistical mediation analysis from reaching its

Improving Communicative Competence through Synchronous Communication in Computer-Supported Collaborative Learning Environments: A Systematic Review

Science.gov (United States)

Huang, Xi

2018-01-01

Computer-supported collaborative learning facilitates the extension of second language acquisition into social practice. Studies on its achievement effects speak directly to the pedagogical notion of treating communicative practice in synchronous computer-mediated communication (SCMC): real-time communication that takes place between human beings…

Allosteric inhibition of SHP2 phosphatase inhibits cancers driven by receptor tyrosine kinases

Energy Technology Data Exchange (ETDEWEB)

Chen, Ying-Nan P.; LaMarche, Matthew J.; Chan, Ho Man; Fekkes, Peter; Garcia-Fortanet, Jorge; Acker, Michael G.; Antonakos, Brandon; Chen, Christine Hiu-Tung; Chen, Zhouliang; Cooke, Vesselina G.; Dobson, Jason R.; Deng, Zhan; Fei, Feng; Firestone, Brant; Fodor, Michelle; Fridrich, Cary; Gao, Hui; Grunenfelder, Denise; Hao, Huai-Xiang; Jacob, Jaison; Ho, Samuel; Hsiao, Kathy; Kang, Zhao B.; Karki, Rajesh; Kato, Mitsunori; Larrow, Jay; La Bonte, Laura R.; Lenoir, Francois; Liu, Gang; Liu, Shumei; Majumdar, Dyuti; Meyer, Matthew J.; Palermo, Mark; Perez, Lawrence; Pu, Minying; Price, Edmund; Quinn, Christopher; Shakya, Subarna; Shultz, Michael D.; Slisz, Joanna; Venkatesan, Kavitha; Wang, Ping; Warmuth, Markus; Williams, Sarah; Yang, Guizhi; Yuan, Jing; Zhang, Ji-Hu; Zhu, Ping; Ramsey, Timothy; Keen, Nicholas J.; Sellers, William R.; Stams, Travis; Fortin , Pascal D. (Novartis)

2016-06-29

The non-receptor protein tyrosine phosphatase SHP2, encoded by PTPN11, has an important role in signal transduction downstream of growth factor receptor signalling and was the first reported oncogenic tyrosine phosphatase1. Activating mutations of SHP2 have been associated with developmental pathologies such as Noonan syndrome and are found in multiple cancer types, including leukaemia, lung and breast cancer and neuroblastoma1, 2, 3, 4, 5. SHP2 is ubiquitously expressed and regulates cell survival and proliferation primarily through activation of the RAS–ERK signalling pathway2, 3. It is also a key mediator of the programmed cell death 1 (PD-1) and B- and T-lymphocyte attenuator (BTLA) immune checkpoint pathways6, 7. Reduction of SHP2 activity suppresses tumour cell growth and is a potential target of cancer therapy8, 9. Here we report the discovery of a highly potent (IC50 = 0.071 μM), selective and orally bioavailable small-molecule SHP2 inhibitor, SHP099, that stabilizes SHP2 in an auto-inhibited conformation. SHP099 concurrently binds to the interface of the N-terminal SH2, C-terminal SH2, and protein tyrosine phosphatase domains, thus inhibiting SHP2 activity through an allosteric mechanism. SHP099 suppresses RAS–ERK signalling to inhibit the proliferation of receptor-tyrosine-kinase-driven human cancer cells in vitro and is efficacious in mouse tumour xenograft models. Together, these data demonstrate that pharmacological inhibition of SHP2 is a valid therapeutic approach for the treatment of cancers.

Understanding the Functional Plasticity in Neural Networks of the Basal Ganglia in Cocaine Use Disorder: A Role for Allosteric Receptor-Receptor Interactions in A2A-D2 Heteroreceptor Complexes

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Dasiel O. Borroto-Escuela

2016-01-01

Full Text Available Our hypothesis is that allosteric receptor-receptor interactions in homo- and heteroreceptor complexes may form the molecular basis of learning and memory. This principle is illustrated by showing how cocaine abuse can alter the adenosine A2AR-dopamine D2R heterocomplexes and their receptor-receptor interactions and hereby induce neural plasticity in the basal ganglia. Studies with A2AR ligands using cocaine self-administration procedures indicate that antagonistic allosteric A2AR-D2R heterocomplexes of the ventral striatopallidal GABA antireward pathway play a significant role in reducing cocaine induced reward, motivation, and cocaine seeking. Anticocaine actions of A2AR agonists can also be produced at A2AR homocomplexes in these antireward neurons, actions in which are independent of D2R signaling. At the A2AR-D2R heterocomplex, they are dependent on the strength of the antagonistic allosteric A2AR-D2R interaction and the number of A2AR-D2R and A2AR-D2R-sigma1R heterocomplexes present in the ventral striatopallidal GABA neurons. It involves a differential cocaine-induced increase in sigma1Rs in the ventral versus the dorsal striatum. In contrast, the allosteric brake on the D2R protomer signaling in the A2AR-D2R heterocomplex of the dorsal striatopallidal GABA neurons is lost upon cocaine self-administration. This is potentially due to differences in composition and allosteric plasticity of these complexes versus those in the ventral striatopallidal neurons.

The Effect of Dynamic Assessment in Synchronous Computer-Mediated Communication on Iranian EFL Learners' Listening Comprehension Ability at Upper-Intermediate Level

Science.gov (United States)

Heidar, Davood Mashhadi; Afghari, Akbar

2015-01-01

The present paper concentrates on a web-based inquiry in the synchronous computer-mediated communication (SCMC) via Web 2.0 technologies of Talk and Write and Skype. It investigates EFL learners' socio-cognitive progress through dynamic assessment (DA), which follows Vygotsky's inclination for supportive interchange in the zone of proximal…

Computer-mediated communication: task performance and satisfaction.

Science.gov (United States)

Simon, Andrew F

2006-06-01

The author assessed satisfaction and performance on 3 tasks (idea generation, intellective, judgment) among 75 dyads (N = 150) working through 1 of 3 modes of communication (instant messaging, videoconferencing, face to face). The author based predictions on the Media Naturalness Theory (N. Kock, 2001, 2002) and on findings from past researchers (e.g., D. M. DeRosa, C. Smith, & D. A. Hantula, in press) of the interaction between tasks and media. The present author did not identify task performance differences, although satisfaction with the medium was lower among those dyads communicating through an instant-messaging system than among those interacting face to face or through videoconferencing. The findings support the Media Naturalness Theory. The author discussed them in relation to the participants' frequent use of instant messaging and their familiarity with new communication media.

Allosteric conformational barcodes direct signaling in the cell.

Science.gov (United States)

Nussinov, Ruth; Ma, Buyong; Tsai, Chung-Jung; Csermely, Peter

2013-09-03

The cellular network is highly interconnected. Pathways merge and diverge. They proceed through shared proteins and may change directions. How are cellular pathways controlled and their directions decided, coded, and read? These questions become particularly acute when we consider that a small number of pathways, such as signaling pathways that regulate cell fates, cell proliferation, and cell death in development, are extensively exploited. This review focuses on these signaling questions from the structural standpoint and discusses the literature in this light. All co-occurring allosteric events (including posttranslational modifications, pathogen binding, and gain-of-function mutations) collectively tag the protein functional site with a unique barcode. The barcode shape is read by an interacting molecule, which transmits the signal. A conformational barcode provides an intracellular address label, which selectively favors binding to one partner and quenches binding to others, and, in this way, determines the pathway direction, and, eventually, the cell's response and fate. Copyright © 2013 Elsevier Ltd. All rights reserved.

The mediating role of partner communication skills on HIV/STD-associated risk behaviors in young African American females with a history of sexual violence.

Science.gov (United States)

Sales, Jessica McDermott; Salazar, Laura F; Wingood, Gina M; DiClemente, Ralph J; Rose, Eve; Crosby, Richard A

2008-05-01

To examine the prevalence of sexual violence among young African American females and to explore the mediating role that partner communication plays on human immunodeficiency virus (HIV)/sexually transmitted disease-associated risk behaviors among youth with a history of sexual violence relative to those without. Only data from baseline, before randomization, were used for this analysis. A clinic-based sample of young females enrolled in a randomized trial of an HIV-prevention program in Atlanta, Georgia, from March 2002 to August 2004. African American females aged 15 to 21 years who reported sexual activity in the previous 60 days. Of 1558 screened, 874 females were eligible and 82% (n = 715) participated at baseline. History of sexual violence as well as (1) sexual partner communication skills, (2) current sexual behaviors, and (3) psychological well-being. Lifetime prevalence of sexual violence was 26%. Communication skills partially mediated the relationship between sexual violence and psychological well-being and sexual behavior outcomes. Given the lifetime prevalence of sexual violence and its adverse sexual, psychological, and relational sequelae, it is paramount that effective interventions are developed. Based on our findings, improving partner communications skills is one particularly important area for HIV/sexually transmitted disease risk-reduction interventions for youths with a history of sexual violence.

Language, mobile phones and internet : a study of SMS texting, email, IM and SNS chats in computer mediated communication (CMC) in Kenya

NARCIS (Netherlands)

Barasa, Sandra Nekesa

2010-01-01

This book examines the use of language in Computer Mediated Communication (CMC) genres in Kenya. It focuses on Short Messaging Service (SMS), Email, Instant Messages (IM) and Social Network Sites (SNS) genres. It presents an overview of the use and characteristics of Kenyan languages in CMC texts

Machine Translation Effect on Communication

DEFF Research Database (Denmark)

Jensen, Mika Yasuoka; Bjørn, Pernille

2011-01-01

Intercultural collaboration facilitated by machine translation has gradually spread in various settings. Still, little is known as for the practice of machine-translation mediated communication. This paper investigates how machine translation affects intercultural communication in practice. Based...... on communication in which multilingual communication system is applied, we identify four communication types and its’ influences on stakeholders’ communication process, especially focusing on establishment and maintenance of common ground. Different from our expectation that quality of machine translation results...

Improving Communicative Competence through Synchronous Communication in Computer-Supported Collaborative Learning Environments: A Systematic Review

Directory of Open Access Journals (Sweden)

Xi Huang

2018-01-01

Full Text Available Computer-supported collaborative learning facilitates the extension of second language acquisition into social practice. Studies on its achievement effects speak directly to the pedagogical notion of treating communicative practice in synchronous computer-mediated communication (SCMC: real-time communication that takes place between human beings via the instrumentality of computers in forms of text, audio and video communication, such as live chat and chatrooms as socially-oriented meaning construction. This review begins by considering the adoption of social interactionist views to identify key paradigms and supportive principles of computer-supported collaborative learning. A special focus on two components of communicative competence is then presented to explore interactional variables in synchronous computer-mediated communication along with a review of research. There follows a discussion on a synthesis of interactional variables in negotiated interaction and co-construction of knowledge from psycholinguistic and social cohesion perspectives. This review reveals both possibilities and disparities of language socialization in promoting intersubjective learning and diversifying the salient use of interactively creative language in computer-supported collaborative learning environments in service of communicative competence.

Alternative communication in an amyotrophic lateral sclerosis case: a mediated educational experience for humanization - doi: 10.4025/actascieduc.v34i1.14505

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Tania dos Santos Alvarez da Silva

2012-05-01

Full Text Available Current analysis is a study on alternative and assisted communication to understand the care specifications of people with amyotrophic lateral sclerosis. The study results from a teaching project Olhar que fala [Eyes that speak], supported by the State University of Maringá (April - October 2010 funded by Historical and Cultural Psychology. The latter considers language as an essential condition for humanization and current study aims at finding alternatives for the expression of thought by people disease-hindered to establish effective oral, verbal, written and sign communication. Methodology used was the register of letters printed on a frame so that the diseased person might indicate the letters by eye movements with a subsequent composition of words and phrases by a mediating researcher. Mediation was undertaken by undergraduates of the Pedagogy Course of the State University of Maringá. Results show that the appropriation activities of contents by the diseased persons could be maintained since they were not deprived of consciousness, hearing and sight. The process also allowed the objectivization of contents and the testing of a low-tech alternative communication for people with amyotrophic lateral sclerosis.

Comunicación, lenguaje y pedagogía: una mirada desde las mediaciones Communication, language and pedagogy: a view from the mediations

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Tomás Vásquez Arrieta

2009-06-01

Full Text Available El presente trabajo se propone exponer, de modo general, el concepto de mediación y su importancia para la comprensión de la comunicación y el lenguaje y su importancia en la práctica pedagógica. En un primer momento se presenta una breve semblanza histórica del concepto de mediación en la tradición filosófica. Posteriormente, se presentan algunas consideraciones de la mediación en el marco de la problemática de la comunicación y del lenguaje desde la propuesta fenomenológica de Merleau-Ponty. Finalmente, se relaciona la reflexión anterior con algunas consideraciones sobre el campo de la pedagogía.This paper presents, in a general way, the concept of mediation and its importance for the comprehension of communication and language, as well as its importance in the pedagogical context. First, there is a short historical description about the concept of mediation in the philosophy tradition. After, some considerations of mediation from the point of view of communication and language and the phenomenological proposal of language of Merleau-Ponty are presented. Finally, the relationship between the reflections made and some considerations about the pedagogical field are shown.

Structure and allosteric effects of low-molecular-weight activators on the protein kinase PDK1

DEFF Research Database (Denmark)

Hindie, Valerie; Stroba, Adriana; Zhang, Hua

2009-01-01

-dependent activation of AGC kinases. The AGC kinase PDK1 is activated by the docking of a phosphorylated motif from substrates. Here we present the crystallography of PDK1 bound to a rationally developed low-molecular-weight activator and describe the conformational changes induced by small compounds in the crystal...... molecular details of the allosteric changes induced by small compounds that trigger the activation of PDK1 through mimicry of phosphorylation-dependent conformational changes....

Cocaine self-administration differentially affects allosteric A2A-D2 receptor-receptor interactions in the striatum. Relevance for cocaine use disorder.

Science.gov (United States)

Pintsuk, Julia; Borroto-Escuela, Dasiel O; Pomierny, Bartosz; Wydra, Karolina; Zaniewska, Magdalena; Filip, Malgorzata; Fuxe, Kjell

2016-05-01

In the current study behavioral and biochemical experiments were performed to study changes in the allosteric A2AR-D2R interactions in the ventral and dorsal striatum after cocaine self-administration versus corresponding yoked saline control. By using ex vivo [(3)H]-raclopride/quinpirole competition experiments, the effects of the A2AR agonist CGS 21680 (100 nM) on the KiH and KiL values of the D2-like receptor (D2-likeR) were determined. One major result was a significant reduction in the D2-likeR agonist high affinity state observed with CGS 21680 after cocaine self-administration in the ventral striatum compared with the yoked saline group. The results therefore support the hypothesis that A2AR agonists can at least in part counteract the motivational actions of cocaine. This action is mediated via the D2-likeR by targeting the A2AR protomer of A2AR-D2-like R heteroreceptor complexes in the ventral striatum, which leads to the reduction of D2-likeR protomer recognition through the allosteric receptor-receptor interaction. In contrast, in the dorsal striatum the CGS 21680-induced antagonistic modulation in the D2-likeR agonist high affinity state was abolished after cocaine self-administration versus the yoked saline group probably due to a local dysfunction/disruption of the A2AR-D2-like R heteroreceptor complexes. Such a change in the dorsal striatum in cocaine self-administration can contribute to the development of either locomotor sensitization, habit-forming learning and/or the compulsive drug seeking by enhanced D2-likeR protomer signaling. Potential differences in the composition and stoichiometry of the A2AR-D2R heteroreceptor complexes, including differential recruitment of sigma 1 receptor, in the ventral and dorsal striatum may explain the differential regional changes observed in the A2A-D2-likeR interactions after cocaine self-administration. Copyright © 2016 Elsevier Inc. All rights reserved.

Relating Communications Mode Choice and Teamwork Quality: Conversational versus Textual Communication in IT System and Software Development Teams

Science.gov (United States)

Smith, James Robert

2012-01-01

This cross-sectional study explored how IT system and software development team members communicated in the workplace and whether teams that used more verbal communication (and less text-based communication) experienced higher levels of collaboration as measured using the Teamwork Quality (TWQ) scale. Although computer-mediated communication tools…

Quantitative Communication Research: Review, Trends, and Critique

Directory of Open Access Journals (Sweden)

Timothy R. Levine

2013-01-01

Full Text Available Trends in quantitative communication research are reviewed. A content analysis of 48 articles reporting original communication research published in 1988-1991 and 2008-2011 is reported. Survey research and self-report measurement remain common approaches to research. Null hypothesis significance testing remains the dominant approach to statistical analysis. Reporting the shapes of distributions, estimates of statistical power, and confidence intervals remain uncommon. Trends over time include the increased popularity of health communication and computer mediated communication as topics of research, and increased attention to mediator and moderator variables. The implications of these practices for scientific progress are critically discussed, and suggestions for the future are provided.

A touch of affect: mediated social touch and affect

NARCIS (Netherlands)

Huisman, Gijs

2012-01-01

This position paper outlines the first stages in an ongoing PhD project on mediated social touch, and the effects mediated touch can have on someone's affective state. It is argued that touch is a profound communication channel for humans, and that communication through touch can, to some extent,

Communication, Technology, Temporality

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Mark A. Martinez

2012-08-01

Full Text Available This paper proposes a media studies that foregrounds technological objects as communicative and historical agents. Specifically, I take the digital computer as a powerful catalyst of crises in communication theories and certain key features of modernity. Finally, the computer is the motor of “New Media” which is at once a set of technologies, a historical epoch, and a field of knowledge. As such the computer shapes “the new” and “the future” as History pushes its origins further in the past and its convergent quality pushes its future as a predominate medium. As treatment of information and interface suggest, communication theories observe computers, and technologies generally, for the mediated languages they either afford or foreclose to us. My project describes the figures information and interface for the different ways they can be thought of as aspects of communication. I treat information not as semantic meaning, formal or discursive language, but rather as a physical organism. Similarly an interface is not a relationship between a screen and a human visual intelligence, but is instead a reciprocal, affective and physical process of contact. I illustrate that historically there have been conceptions of information and interface complimentary to mine, fleeting as they have been in the face of a dominant temporality of mediation. I begin with a theoretically informed approach to media history, and extend it to a new theory of communication. In doing so I discuss a model of time common to popular, scientific, and critical conceptions of media technologies especially in theories of computer technology. This is a predominate model with particular rules of temporal change and causality for thinking about mediation, and limits the conditions of possibility for knowledge production about communication. I suggest a new model of time as integral to any event of observation and analysis, and that human mediation does not exhaust the

Effects of the dopamine D2 allosteric modulator, PAOPA, on the expression of GRK2, arrestin-3, ERK1/2, and on receptor internalization.

Directory of Open Access Journals (Sweden)

Dipannita Basu

Full Text Available The activity of G protein-coupled receptors (GPCRs is intricately regulated by a range of intracellular proteins, including G protein-coupled kinases (GRKs and arrestins. Understanding the effects of ligands on these signaling pathways could provide insights into disease pathophysiologies and treatment. The dopamine D2 receptor is a GPCR strongly implicated in the pathophysiology of a range of neurological and neuropsychiatric disorders, particularly schizophrenia. Previous studies from our lab have shown the preclinical efficacy of a novel allosteric drug, 3(R-[(2(S-pyrrolidinylcarbonylamino]-2-oxo-1-pyrrolidineacetamide (PAOPA, in attenuating schizophrenia-like behavioural abnormalities in rodent models of the disease. As an allosteric modulator, PAOPA binds to a site on the D2 receptor, which is distinct from the endogenous ligand-binding site, in order to modulate the binding of the D2 receptor ligand, dopamine. The exact signaling pathways affected by this allosteric modulator are currently unknown. The objectives of this study were to decipher the in vivo effects, in rats, of chronic PAOPA administration on D2 receptor regulatory and downstream molecules, including GRK2, arrestin-3 and extracellular receptor kinase (ERK 1/2. Additionally, an in vitro cellular model was also used to study PAOPA's effects on D2 receptor internalization. Results from western immunoblots showed that chronic PAOPA treatment increased the striatal expression of GRK2 by 41%, arrestin-3 by 34%, phospho-ERK1 by 51% and phospho-ERK2 by 36%. Results also showed that the addition of PAOPA to agonist treatment in cells increased D2 receptor internalization by 33%. This study provides the foundational evidence of putative signaling pathways, and changes in receptor localization, affected by treatment with PAOPA. It improves our understanding on the diverse mechanisms of action of allosteric modulators, while advancing PAOPA's development into a novel drug for the

Positive allosteric modulation of mGluR5 accelerates extinction learning but not relearning following methamphetamine self-administration

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Peter R Kufahl

2012-11-01

Full Text Available Recent studies have implicated glutamate neurotransmission as an important substrate for the extinction of conditioned behaviors, including responding for drug reinforcement. Positive allosteric modulation of the type-5 metabotropic glutamate receptor (mGluR5 in particular has emerged as a treatment strategy for the enhancement of extinction of drug-motivated behaviors. Here, we investigated the effects of the mGluR5 positive allosteric modulator CDPPB, a compound known for its cognitive enhancing effects in rodents, on extinction learning in rats with different histories of methamphetamine (METH training. Rats were trained to self-administer METH under two conditions: 16 daily sessions of short access (90 min/day, ShA, or 8 daily sessions of short access followed by 8 sessions of long access (6 hr/day, LgA. Control rats self-administered sucrose pellets in daily 30 min sessions. Next, rats were administered vehicle or 30 mg/kg CDPPB prior to 7 consecutive daily extinction sessions, subjected to additional extinction sessions to re-establish a post-treatment baseline, and then tested for reinstatement of behavior in the presence of METH- or sucrose-paired cues. Rats were then subjected to a second series of extinction sessions, preceded by vehicle or 30 mg/kg CDPPB, and an additional test for cue-triggered reinstatement. CDPPB treatment resulted in a more rapid extinction of responding on the active lever, especially in the early sessions of the first extinction sequence. However, treatment effects were minimal during subsequent cue reinstatement tests and nonexistent during the second series of extinction sessions. Rats with histories of ShA, LgA and sucrose training expressed similar behavioral sensitivities to CDPPB, with LgA rats demonstrating a modestly higher treatment effect. Positive allosteric modulation of mGluR5 may therefore have some beneficial effects on efforts to facilitate extinction learning and reduce methamphetamine seeking.

Allosteric control of internal electron transfer in cytochrome cd1 nitrite reductase

DEFF Research Database (Denmark)

Farver, Ole; Kroneck, Peter M H; Zumft, Walter G

2003-01-01

Cytochrome cd1 nitrite reductase is a bifunctional multiheme enzyme catalyzing the one-electron reduction of nitrite to nitric oxide and the four-electron reduction of dioxygen to water. Kinetics and thermodynamics of the internal electron transfer process in the Pseudomonas stutzeri enzyme have...... been studied and found to be dominated by pronounced interactions between the c and the d1 hemes. The interactions are expressed both in dramatic changes in the internal electron-transfer rates between these sites and in marked cooperativity in their electron affinity. The results constitute a prime...... example of intraprotein control of the electron-transfer rates by allosteric interactions....

Structural insight to mutation effects uncover a common allosteric site in class C GPCRs

DEFF Research Database (Denmark)

Harpsøe, Kasper; Boesgaard, Michael W; Munk, Christian

2017-01-01

MOTIVATION: Class C G protein-coupled receptors (GPCRs) regulate important physiological functions and allosteric modulators binding to the transmembrane domain constitute an attractive and, due to a lack of structural insight, a virtually unexplored potential for therapeutics and the food industry....... Combining pharmacological site-directed mutagenesis data with the recent class C GPCR experimental structures will provide a foundation for rational design of new therapeutics. RESULTS: We uncover one common site for both positive and negative modulators with different amino acid layouts that can...

Allosteric activation of the follicle-stimulating hormone (FSH) receptor by selective, nonpeptide agonists.

Science.gov (United States)

Yanofsky, Stephen D; Shen, Emily S; Holden, Frank; Whitehorn, Erik; Aguilar, Barbara; Tate, Emily; Holmes, Christopher P; Scheuerman, Randall; MacLean, Derek; Wu, May M; Frail, Donald E; López, Francisco J; Winneker, Richard; Arey, Brian J; Barrett, Ronald W

2006-05-12

The pituitary glycoprotein hormones, luteinizing hormone and follicle-stimulating hormone (FSH), act through their cognate receptors to initiate a series of coordinated physiological events that results in germ cell maturation. Given the importance of FSH in regulating folliculogenesis and fertility, the development of FSH mimetics has been sought to treat infertility. Currently, purified and recombinant human FSH are the only FSH receptor (FSH-R) agonists available for infertility treatment. By screening unbiased combinatorial chemistry libraries, using a cAMP-responsive luciferase reporter assay, we discovered thiazolidinone agonists (EC50's = 20 microm) of the human FSH-R. Subsequent analog library screening and parallel synthesis optimization resulted in the identification of a potent agonist (EC50 = 2 nm) with full efficacy compared with FSH that was FSH-R-selective and -dependent. The compound mediated progesterone production in Y1 cells transfected with the human FSH-R (EC50 = 980 nm) and estradiol production from primary rat ovarian granulosa cells (EC50 = 10.5 nm). This and related compounds did not compete with FSH for binding to the FSH-R. Use of human FSH/thyroid-stimulating hormone (TSH) receptor chimeras suggested a novel mechanism for receptor activation through a binding site independent of the natural hormone binding site. This study is the first report of a high affinity small molecule agonist that activates a glycoprotein hormone receptor through an allosteric mechanism. The small molecule FSH receptor agonists described here could lead to an oral alternative to the current parenteral FSH treatments used clinically to induce ovarian stimulation for both in vivo and in vitro fertilization therapy.

An antibody that prevents serpin polymerisation acts by inducing a novel allosteric behaviour.

Science.gov (United States)

Motamedi-Shad, Neda; Jagger, Alistair M; Liedtke, Maximilian; Faull, Sarah V; Nanda, Arjun Scott; Salvadori, Enrico; Wort, Joshua L; Kay, Christopher W M; Heyer-Chauhan, Narinder; Miranda, Elena; Perez, Juan; Ordóñez, Adriana; Haq, Imran; Irving, James A; Lomas, David A

2016-10-01

Serpins are important regulators of proteolytic pathways with an antiprotease activity that involves a conformational transition from a metastable to a hyperstable state. Certain mutations permit the transition to occur in the absence of a protease; when associated with an intermolecular interaction, this yields linear polymers of hyperstable serpin molecules, which accumulate at the site of synthesis. This is the basis of many pathologies termed the serpinopathies. We have previously identified a monoclonal antibody (mAb4B12) that, in single-chain form, blocks α1-antitrypsin (α1-AT) polymerisation in cells. Here, we describe the structural basis for this activity. The mAb4B12 epitope was found to encompass residues Glu32, Glu39 and His43 on helix A and Leu306 on helix I. This is not a region typically associated with the serpin mechanism of conformational change, and correspondingly the epitope was present in all tested structural forms of the protein. Antibody binding rendered β-sheet A - on the opposite face of the molecule - more liable to adopt an 'open' state, mediated by changes distal to the breach region and proximal to helix F. The allosteric propagation of induced changes through the molecule was evidenced by an increased rate of peptide incorporation and destabilisation of a preformed serpin-enzyme complex following mAb4B12 binding. These data suggest that prematurely shifting the β-sheet A equilibrium towards the 'open' state out of sequence with other changes suppresses polymer formation. This work identifies a region potentially exploitable for a rational design of ligands that is able to dynamically influence α1-AT polymerisation. © 2016 The Author(s).

Substrate-Induced Allosteric Change in the Quaternary Structure of the Spermidine N-Acetyltransferase SpeG

OpenAIRE

Filippova, Ekaterina V.; Weigand, Steven; Osipiuk, Jerzy; Kiryukhina, Olga; Joachimiak, Andrzej; Anderson, Wayne F.

2015-01-01

The spermidine N-acetyltransferase SpeG is a dodecameric enzyme that catalyzes the transfer of an acetyl group from acetyl-coenzyme A to polyamines such as spermidine and spermine. SpeG has an allosteric polyamine-binding site and acetylating polyamines regulates their intracellular concentrations. The structures of SpeG from Vibrio cholerae in complexes with polyamines and cofactor have been characterized earlier. Here, we present the dodecameric structure of SpeG from V. cholerae in a ligan...

Improving Communicative Competence through Synchronous Communication in Computer-Supported Collaborative Learning Environments: A Systematic Review

OpenAIRE

Xi Huang

2018-01-01

Computer-supported collaborative learning facilitates the extension of second language acquisition into social practice. Studies on its achievement effects speak directly to the pedagogical notion of treating communicative practice in synchronous computer-mediated communication (SCMC): real-time communication that takes place between human beings via the instrumentality of computers in forms of text, audio and video communication, such as live chat and chatrooms as socially-oriented meaning c...

Computational redesign reveals allosteric mutation hotspots of organophosphate hydrolase that enhance organophosphate hydrolysis

Energy Technology Data Exchange (ETDEWEB)

Jacob, Reed B. [Univ. of North Carolina, Chapel Hill, NC (United States); Ding, Feng [Clemson Univ., SC (United States); Ye, Dongmei [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ackerman, Eric [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Dokholyan, Nikolay V. [Univ. of North Carolina, Chapel Hill, NC (United States)

2015-04-01

Organophosphates are widely used for peaceful (agriculture) and military purposes (chemical warfare agents). The extraordinary toxicity of organophosphates and the risk of deployment, make it critical to develop means for their rapid and efficient deactivation. Organophosphate hydrolase (OPH) already plays an important role in organophosphate remediation, but is insufficient for therapeutic or prophylactic purposes primarily due to low substrate affinity. Current efforts focus on directly modifying the active site to differentiate substrate specificity and increase catalytic activity. Here, we present a novel strategy for enhancing the general catalytic efficiency of OPH through computational redesign of the residues that are allosterically coupled to the active site and validated our design by mutagenesis. Specifically, we identify five such hot-spot residues for allosteric regulation and assay these mutants for hydrolysis activity against paraoxon, a chemical-weapons simulant. A high percentage of the predicted mutants exhibit enhanced activity over wild-type (k_cat =16.63 s^-1), such as T199I/T54I (899.5 s^-1) and C227V/T199I/T54I (848 s^-1), while the Km remains relatively unchanged in our high-throughput cell-free expression system. Further computational studies of protein dynamics reveal four distinct distal regions coupled to the active site that display significant changes in conformation dynamics upon these identified mutations. These results validate a computational design method that is both efficient and easily adapted as a general procedure for enzymatic enhancement.

Social Presence in the Web-Based Classroom: Implications for Intercultural Communication

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Yildiz, Senem

2009-01-01

Social presence is a theory derived from social psychology to explain social interactions in a mediated communication and is defined as the degree to which interlocutors in a communications medium perceive each other as real. This study investigates the effect of computer-mediated communication on the social presence of international students who…

Allosteric inactivation of a trypsin-like serine protease by an antibody binding to the 37- and 70-loops

DEFF Research Database (Denmark)

Kromann-Hansen, Tobias; Lund, Ida K; Liu, Zhuo

2013-01-01

for elucidating fundamental allosteric mechanisms. The monoclonal antibody mU1 has previously been shown to be able to inhibit the function of murine urokinase-type plasminogen activator in vivo. We have now mapped the epitope of mU1 to the catalytic domain's 37- and 70-loops, situated about 20 Å from the S1...

A New Negative Allosteric Modulator AP14145 for the Study of Small Conductance Calcium-Activated Potassium Channels

DEFF Research Database (Denmark)

Simo Vicens, Rafel; Kirchhoff, Jeppe Egedal; Dolce, Bernardo

2017-01-01

) prolongation in anaesthetised rats and a beam walk test was performed in mice to determine acute CNS related effects of the drug. Key results: AP14145 was found to be an equipotent negative allosteric modulator of KCa2.2 and KCa2.3 channels (IC50 = 1.1 ± 0.3 μM L-1). The presence of AP14145 (10 μM L-1......) increased the EC50 of Ca2+ on KCa2.3 from 0.36 ± 0.02 μM L-1 to 1.2 ± 0.1 μM L-1. The inhibitory effect strongly depended on two amino acids, S508 and A533. AP14145 concentration-dependently prolonged AERP in rats. Moreover, AP14145 (10 mg kg-1) did not trigger any apparent CNS effects in mice. Conclusion...... and implications: AP14145 is a negative allosteric modulator of KCa2.2 and KCa2.3 that shifts the calcium dependence of channel activation, an effect strongly dependent on two identified amino acids. AP14145 prolongs AERP in rats and does not trigger any acute CNS effects in mice. The understanding of how KCa2...

SIREN : mediated informal communication for serendipity

NARCIS (Netherlands)

Batalas, N.; Markopoulos, P.

2010-01-01

The process of education and innovation often involves individuals, whose expertise lies in diverse fields. Informal communication amongst them can prove to be invaluable towards their collaboration, but rarely does it extend beyond one’s already established social circle. This paper proposes SIREN,

GGPP-Mediated Protein Geranylgeranylation in Oocyte Is Essential for the Establishment of Oocyte-Granulosa Cell Communication and Primary-Secondary Follicle Transition in Mouse Ovary.

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Chen Jiang

2017-01-01

Full Text Available Folliculogenesis is a progressive and highly regulated process, which is essential to provide ova for later reproductive life, requires the bidirectional communication between the oocyte and granulosa cells. This physical connection-mediated communication conveys not only the signals from the oocyte to granulosa cells that regulate their proliferation but also metabolites from the granulosa cells to the oocyte for biosynthesis. However, the underlying mechanism of establishing this communication is largely unknown. Here, we report that oocyte geranylgeranyl diphosphate (GGPP, a metabolic intermediate involved in protein geranylgeranylation, is required to establish the oocyte-granulosa cell communication. GGPP and geranylgeranyl diphosphate synthase (Ggpps levels in oocytes increased during early follicular development. The selective depletion of GGPP in mouse oocytes impaired the proliferation of granulosa cells, primary-secondary follicle transition and female fertility. Mechanistically, GGPP depletion inhibited Rho GTPase geranylgeranylation and its GTPase activity, which was responsible for the accumulation of cell junction proteins in the oocyte cytoplasm and the failure to maintain physical connection between oocyte and granulosa cells. GGPP ablation also blocked Rab27a geranylgeranylation, which might account for the impaired secretion of oocyte materials such as Gdf9. Moreover, GGPP administration restored the defects in oocyte-granulosa cell contact, granulosa cell proliferation and primary-secondary follicle transition in Ggpps depletion mice. Our study provides the evidence that GGPP-mediated protein geranylgeranylation contributes to the establishment of oocyte-granulosa cell communication and then regulates the primary-secondary follicle transition, a key phase of folliculogenesis essential for female reproductive function.

Is intercultural mediation necessary? An approach from a communications perspective

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Susana Ridao Rodrigo

2014-10-01

Full Text Available Institutionalized intercultural mediation is expanding as a result of the increase in the number of immigrants in our country. Institutionalized intercultural mediation, which started in the early Nineties in Spain, is understood to mean activities carried out by ONGs and by the social services of the host nation. In line with Giménez (1997: 127, we understand intercultural mediation as a modality within the broader field of mediation. Because of its recent expansion, there is not at present a unique methodology accepted by experts in this field. In this paper, our aims are focused on describing various mediation techniques and the possibility of their application within intercultural contexts

Digital technology use among disadvantaged Australians: implications for equitable consumer participation in digitally-mediated communication and information exchange with health services.

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Newman, Lareen; Biedrzycki, Kate; Baum, Fran

2012-05-01

To present research findings on access to, and use of, digital information and communication technologies (ICTs) by Australians from lower income and disadvantaged backgrounds to determine implications for equitable consumer access to digitally-mediated health services and information. Focus groups were held in 2008-09 with 80 residents from lower income and disadvantaged backgrounds in South Australia, predominantly of working- and family-formation age (25 to 55 years). Qualitative analysis was conducted on a-priori and emergent themes to describe dominant categories. Access to, and use of, computers, the Internet and mobile phones varied considerably in extent, frequency and quality within and across groups due to differences in abilities, resources and life experience. Barriers and facilitators included English literacy (including for native speakers), technological literacy, education, income, housing situation, social connection, health status, employment status, and trust. Many people gained ICT skills by trial and error or help from friends, and only a few from formal programs, resulting in varied skills. The considerable variation in ICT access and use within lower income and disadvantaged groups must be acknowledged and accommodated by health initiatives and services when delivering digitally-mediated consumer-provider interaction, online health information, or online self-management of health conditions. If services require consumers to participate in a digitally-mediated communication exchange, then we suggest they might support skills and technology acquisition, or provide non-ICT alternatives, in order to avoid exacerbating health inequities.

Virtual microscopy: merging of computer mediated communication and intuitive interfacing

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de Ridder, Huib; de Ridder-Sluiter, Johanna G.; Kluin, Philip M.; Christiaans, Henri H. C. M.

2009-02-01

Ubiquitous computing (or Ambient Intelligence) is an upcoming technology that is usually associated with futuristic smart environments in which information is available anytime anywhere and with which humans can interact in a natural, multimodal way. However spectacular the corresponding scenarios may be, it is equally challenging to consider how this technology may enhance existing situations. This is illustrated by a case study from the Dutch medical field: central quality reviewing for pathology in child oncology. The main goal of the review is to assess the quality of the diagnosis based on patient material. The sharing of knowledge in social face-to-face interaction during such meeting is an important advantage. At the same time there is the disadvantage that the experts from the seven Dutch academic medical centers have to travel to the review meeting and that the required logistics to collect and bring patient material and data to the meeting is cumbersome and time-consuming. This paper focuses on how this time-consuming, nonefficient way of reviewing can be replaced by a virtual collaboration system by merging technology supporting Computer Mediated Collaboration and intuitive interfacing. This requires insight in the preferred way of communication and collaboration as well as knowledge about preferred interaction style with a virtual shared workspace.

The use of mediation analysis to assess the effects of a behaviour change communication strategy on bed net ideation and household universal coverage in Tanzania.

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Ricotta, Emily E; Boulay, Marc; Ainslie, Robert; Babalola, Stella; Fotheringham, Megan; Koenker, Hannah; Lynch, Matthew

2015-01-21

SBCC campaigns are designed to act on cognitive, social and emotional factors at the individual or community level. The combination of these factors, referred to as 'ideation', play a role in determining behaviour by reinforcing and confirming decisions about a particular health topic. This study introduces ideation theory and mediation analysis as a way to evaluate the impact of a malaria SBCC campaign in Tanzania, to determine whether exposure to a communication programme influenced universal coverage through mediating ideational variables. A household survey in three districts where community change agents (CCAs) were active was conducted to collect information on ITN use, number of ITNs in the household, and perceptions about ITN use and ownership. Variables relating to attitudes and beliefs were combined to make 'net ideation'. Using an ideational framework, a mediation analysis was conducted to see the impact exposure to a CCA only, mass media and community (M & C) messaging only, or exposure to both, had on household universal coverage, through the mediating variable net ideation. All three levels of exposure (CCA, M & C messaging, or exposure to both) were significantly associated with increased net ideation (CCA: 0.283, 95% CI: 0.136-0.429, p-value: mediation analysis is an applicable new tool to assess SBCC campaigns. Ideation as a mediator of the effects of communication exposure on household universal coverage has implications for designing SBCC to support both mass and continuous distribution efforts, since both heavily rely on consumer participation to obtain and maintain ITNs. Such systems can be strengthened by SBCC programming, generating demand through improving social norms about net ownership and use, perceived benefits of nets, and other behavioural constructs.

Substrate-Induced Allosteric Change in the Quaternary Structure of the Spermidine N-Acetyltransferase SpeG.

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Filippova, Ekaterina V; Weigand, Steven; Osipiuk, Jerzy; Kiryukhina, Olga; Joachimiak, Andrzej; Anderson, Wayne F

2015-11-06

The spermidine N-acetyltransferase SpeG is a dodecameric enzyme that catalyzes the transfer of an acetyl group from acetyl coenzyme A to polyamines such as spermidine and spermine. SpeG has an allosteric polyamine-binding site and acetylating polyamines regulate their intracellular concentrations. The structures of SpeG from Vibrio cholerae in complexes with polyamines and cofactor have been characterized earlier. Here, we present the dodecameric structure of SpeG from V. cholerae in a ligand-free form in three different conformational states: open, intermediate and closed. All structures were crystallized in C2 space group symmetry and contain six monomers in the asymmetric unit cell. Two hexamers related by crystallographic 2-fold symmetry form the SpeG dodecamer. The open and intermediate states have a unique open dodecameric ring. This SpeG dodecamer is asymmetric except for the one 2-fold axis and is unlike any known dodecameric structure. Using a fluorescence thermal shift assay, size-exclusion chromatography with multi-angle light scattering, small-angle X-ray scattering analysis, negative-stain electron microscopy and structural analysis, we demonstrate that this unique open dodecameric state exists in solution. Our combined results indicate that polyamines trigger conformational changes and induce the symmetric closed dodecameric state of the protein when they bind to their allosteric sites. Copyright © 2015. Published by Elsevier Ltd.

The selective positive allosteric M1 muscarinic receptor modulator PQCA attenuates learning and memory deficits in the Tg2576 Alzheimer's disease mouse model.

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Puri, Vanita; Wang, Xiaohai; Vardigan, Joshua D; Kuduk, Scott D; Uslaner, Jason M

2015-01-01

We have recently shown that the M1 muscarinic receptor positive allosteric modulator, PQCA, improves cognitive performance in rodents and non-human primates administered the muscarinic receptor antagonist scopolamine. The purpose of the present experiments was to characterize the effects of PQCA in a model more relevant to the disease pathology of Alzheimer's disease. Tg2576 transgenic mice that have elevated Aβ were tested in the novel object recognition task to characterize recognition memory as a function of age and treatment with the PQCA. The effects of PQCA were compared to the acetylcholinesterase inhibitor donepezil, the standard of care for Alzheimer's disease. In addition, the effect of co-administering PQCA and donepezil was evaluated. Aged Tg2576 mice demonstrated a deficit in recognition memory that was significantly attenuated by PQCA. The positive control donepezil also reversed the deficit. Furthermore, doses of PQCA and donepezil that were inactive on their own were found to improve recognition memory when given together. These studies suggest that M1 muscarinic receptor positive allosteric modulation can ameliorate memory deficits in disease relevant models of Alzheimer's disease. These data, combined with our previous findings demonstrating PQCA improves scopolamine-induced cognitive deficits in both rodents and non-human primates, suggest that M1 positive allosteric modulators have therapeutic potential for the treatment of Alzheimer's disease. Copyright © 2015 Elsevier B.V. All rights reserved.

Communication Competence, Psychological Well-being, and the Mediating Role of Coping Efforts among Women with Breast Cancer: Cross-sectional and Longitudinal Evidence

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Shim, Minsun; Mercer Kollar, Laura M.; Roberts, Linda; Gustafson, David

2015-01-01

Despite existing research identifying psychological benefits of patients’ interpersonal competence in various contexts, little longitudinal research has addressed underlying mechanism(s). To address this limitation, we examined both the cross-sectional and longitudinal associations between cancer patients’ communication competence in close relationships and psychological well-being, as well as the mediating role of coping efforts. Data came from a larger project with women with breast cancer (N = 661), recruited from April 2005 to May 2007 at three large university-affiliated cancer centers in the U.S. to study the effects of an Internet-based system providing patients and families with a range of services. The present study focused on survey data at baseline, 6 weeks, and 12 weeks after the intervention (controlling for the possible effects of the intervention). Results from both cross-sectional and longitudinal analyses indicated that competence in open communication between patients and their close support persons had a positive association with patients’ psychological well-being and that approach coping efforts partially mediated this association. We discussed the implications and limitations of the study. PMID:25793748

A New Negative Allosteric Modulator AP14145 for the Study of Small Conductance Calcium-Activated Potassium Channels

DEFF Research Database (Denmark)

Simo Vicens, Rafel; Kirchhoff, Jeppe Egedal; Dolce, Bernardo

2017-01-01

) prolongation in anaesthetised rats and a beam walk test was performed in mice to determine acute CNS related effects of the drug. Key results: AP14145 was found to be an equipotent negative allosteric modulator of KCa2.2 and KCa2.3 channels (IC50 = 1.1 ± 0.3 μM L-1). The presence of AP14145 (10 μM L-1...

Inversion of allosteric effect of arginine on N-acetylglutamate synthase, a molecular marker for evolution of tetrapods

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Cabrera-Luque Juan

2008-09-01

Full Text Available Abstract Background The efficient conversion of ammonia, a potent neurotoxin, into non-toxic metabolites was an essential adaptation that allowed animals to move from the aquatic to terrestrial biosphere. The urea cycle converts ammonia into urea in mammals, amphibians, turtles, snails, worms and many aquatic animals and requires N-acetylglutamate (NAG, an essential allosteric activator of carbamylphosphate synthetase I (CPSI in mammals and amphibians, and carbamylphosphate synthetase III (CPSIII in fish and invertebrates. NAG-dependent CPSI and CPSIII catalyze the formation of carbamylphosphate in the first and rate limiting step of ureagenesis. NAG is produced enzymatically by N-acetylglutamate synthase (NAGS, which is also found in bacteria and plants as the first enzyme of arginine biosynthesis. Arginine is an allosteric inhibitor of microbial and plant NAGS, and allosteric activator of mammalian NAGS. Results Information from mutagenesis studies of E. coli and P. aeruginosa NAGS was combined with structural information from the related bacterial N-acetylglutamate kinases to identify four residues in mammalian NAGS that interact with arginine. Substitutions of these four residues were engineered in mouse NAGS and into the vertebrate-like N-acetylglutamate synthase-kinase (NAGS-K of Xanthomonas campestris, which is inhibited by arginine. All mutations resulted in arginine losing the ability to activate mouse NAGS, and inhibit X. campestris NAGS-K. To examine at what point in evolution inversion of arginine effect on NAGS occur, we cloned NAGS from fish and frogs and examined the arginine response of their corresponding proteins. Fish NAGS were partially inhibited by arginine and frog NAGS were activated by arginine. Conclusion Difference in arginine effect on bacterial and mammalian NAGS most likely stems from the difference in the type of conformational change triggered by arginine binding to these proteins. The change from arginine

Correction for Inhibition Leads to an Allosteric Co-Agonist Model for Pentobarbital Modulation and Activation of α1β3γ2L GABAA Receptors.

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Alexis M Ziemba

Full Text Available Pentobarbital, like propofol and etomidate, produces important general anesthetic effects through GABAA receptors. Photolabeling also indicates that pentobarbital binds to some of the same sites where propofol and etomidate act. Quantitative allosteric co-agonist models for propofol and etomidate account for modulatory and agonist effects in GABAA receptors and have proven valuable in establishing drug site characteristics and for functional analysis of mutants. We therefore sought to establish an allosteric co-agonist model for pentobarbital activation and modulation of α1β3γ2L receptors, using a novel approach to first correct pentobarbital activation data for inhibitory effects in the same concentration range.Using oocyte-expressed α1β3γ2L GABAA receptors and two-microelectrode voltage-clamp, we quantified modulation of GABA responses by a low pentobarbital concentration and direct effects of high pentobarbital concentrations, the latter displaying mixed agonist and inhibitory effects. We then isolated and quantified pentobarbital inhibition in activated receptors using a novel single-sweep "notch" approach, and used these results to correct steady-state direct activation for inhibition.Combining results for GABA modulation and corrected direct activation, we estimated receptor open probability and optimized parameters for a Monod-Wyman-Changeux allosteric co-agonist model. Inhibition by pentobarbital was consistent with two sites with IC50s near 1 mM, while co-agonist model parameters suggest two allosteric pentobarbital agonist sites characterized by KPB ≈ 5 mM and high efficacy. The results also indicate that pentobarbital may be a more efficacious agonist than GABA.Our novel approach to quantifying both inhibitory and co-agonist effects of pentobarbital provides a basis for future structure-function analyses of GABAA receptor mutations in putative pentobarbital binding sites.

Pharmacological characterization and modeling of the binding sites of novel 1,3-bis(pyridinylethynyl)benzenes as metabotropic glutamate receptor 5-selective negative allosteric modulators

DEFF Research Database (Denmark)

Mølck, Christina; Harpsøe, Kasper; Gloriam, David E

2012-01-01

)pyridine (MPEP)-derived negative allosteric modulators, 2-, 3-, and 4-BisPEB, have been characterized. 2-, 3-, and 4-BisPEB are 1,3-bis(pyridinylethynyl)-benzenes and differ only by the position of the nitrogen atoms in the pyridine rings. Despite their high structural similarity, 2-BisPEB [1,3-bis(pyridin-2......-ylethynyl)-benzene, nitrogen atoms in ortho positions], with an IC(50) value in the nanomolar range, is significantly more potent than the 3- and 4-pyridyl analogs. Mutational analysis, directed by a previously published mGluR5 homology model, was used to determine key residues for the ligand...... that the higher potency of 2-BisPEB is due to hydrogen bonding to Ser809 because the S809A mutation made 2-BisPEB equipotent to 3- and 4-BisPEB (IC(50), 1-2.5 µM). The potency of MPEP was also greatly affected by S809A (52-fold), suggesting that a Ser809-mediated hydrogen bond is also a key interaction between...

Ras activation by SOS: Allosteric regulation by altered fluctuation dynamics

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Iversen, Lars; Tu, Hsiung-Lin; Lin, Wan-Chen; Christensen, Sune M.; Abel, Steven M.; Iwig, Jeff; Wu, Hung-Jen; Gureasko, Jodi; Rhodes, Christopher; Petit, Rebecca S.; Hansen, Scott D.; Thill, Peter; Yu, Cheng-Han; Stamou, Dimitrios; Chakraborty, Arup K.; Kuriyan, John; Groves, Jay T.

2014-01-01

Activation of the small guanosine triphosphatase H-Ras by the exchange factor Son of Sevenless (SOS) is an important hub for signal transduction. Multiple layers of regulation, through protein and membrane interactions, govern activity of SOS. We characterized the specific activity of individual SOS molecules catalyzing nucleotide exchange in H-Ras. Single-molecule kinetic traces revealed that SOS samples a broad distribution of turnover rates through stochastic fluctuations between distinct, long-lived (more than 100 seconds), functional states. The expected allosteric activation of SOS by Ras–guanosine triphosphate (GTP) was conspicuously absent in the mean rate. However, fluctuations into highly active states were modulated by Ras-GTP. This reveals a mechanism in which functional output may be determined by the dynamical spectrum of rates sampled by a small number of enzymes, rather than the ensemble average. PMID:24994643

Barriers to Communication in Distance Education

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Berge, Zane L.

2013-01-01

To a large extent education can be thought of as a communication process among the participants. This article focuses on distance education, which has both the general communication processes that in-person education venues possess, and also communication specific to the technologies that mediate the teaching and learning taking place at a…

From socially prescribed perfectionism to problematic use of internet communicative services: the mediating roles of perceived social support and the fear of negative evaluation.

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Casale, Silvia; Fioravanti, Giulia; Flett, Gordon L; Hewitt, Paul L

2014-12-01

The present study developed and tested a model that explains how people who believe that others have unrealistically high standards and exert pressure on them to be perfect (that is, people high in socially prescribed perfectionism) develop a problematic use of internet communicative services (GPIU). Following the perfectionism social disconnection model and previous evidence about the role that the online environment might play in the development of problematic internet use, low reported social support and the fear of negative evaluations in face to face interactions were hypothesized to mediate the association between socially prescribed perfectionism and GPIU. A sample of 465 undergraduate students was recruited (240 F; mean age 21.91+2.23years), and the hypotheses were tested through structural equation modeling separately for men and women. Among men, the association between SPP and GPIU was fully mediated by the fear of being negatively evaluated and the perception of low social support. For women, we found a partially mediated model in which SPP affected GPIU indirectly through the fear of negative evaluations. The presence of a direct effect of SPP on GPIU was also found. Moreover, perceived social support was not found to be a significant mediator among women. The findings suggest that problematic use of internet communicative services might be, at least in part, a defensive response to extreme social evaluation pressures. Copyright © 2014 Elsevier Ltd. All rights reserved.

Selective Allosteric Antagonists for the G Protein-Coupled Receptor GPRC6A Based on the 2-Phenylindole Privileged Structure Scaffold

DEFF Research Database (Denmark)

Johansson, Henrik; Boesgaard, Michael Worch; Nørskov-Lauritsen, Lenea

2015-01-01

G protein-coupled receptors (GPCRs) represent a biological target class of fundamental importance in drug therapy. The GPRC6A receptor is a newly deorphanized class C GPCR that we recently reported for the first allosteric antagonists based on the 2-arylindole privileged structure scaffold (e.g., 1...

Computer-Mediated Communication Preferences and Individual Differences in Neurocognitive Measures of Emotional Attention Capture, Reactivity and Regulation

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Babkirk, Sarah; Luehring-Jones, Peter; Dennis, Tracy A.

2016-01-01

The use of computer-mediated communication (CMC) to engage socially has become increasingly prevalent, yet few studies examined individual differences that may shed light on implications of CMC for adjustment. The current study examined neurocognitive individual differences associated with preferences to use technology in relation to social-emotional outcomes. In Study 1 (N =91), a self-report measure, the Social Media Communication Questionnaire (SMCQ), was evaluated as an assessment of preferences for communicating positive and negative emotions on a scale ranging from purely via CMC to purely face-to-face. In Study 2, SMCQ preferences were examined in relation to event-related potentials (ERPs) associated with early emotional attention capture and reactivity (the frontal N1) and later sustained emotional processing and regulation [the late positive potential (LPP)]. Electroencephalography (EEG) was recorded while 22 participants passively viewed emotional and neutral pictures and completed an emotion regulation task with instructions to increase, decrease or maintain their emotional responses. A greater preference for CMC was associated with reduced size of and satisfaction with social support, greater early (N1) attention capture by emotional stimuli, and reduced LPP amplitudes to unpleasant stimuli in the increase emotion regulatory task. These findings are discussed in the context of possible emotion- and social-regulatory functions of CMC. PMID:26613269

Escitalopram, an antidepressant with an allosteric effect at the serotonin transporter--a review of current understanding of its mechanism of action.

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Zhong, Huailing; Haddjeri, Nasser; Sánchez, Connie

2012-01-01

Escitalopram is a widely used antidepressant for the treatment of patients with major depression. It is the pure S-enantiomer of racemic citalopram. Several clinical trials and meta-analyses indicate that escitalopram is quantitatively more efficacious than many other antidepressants with a faster onset of action. This paper reviews current knowledge about the mechanism of action of escitalopram. The primary target for escitalopram is the serotonin transporter (SERT), which is responsible for serotonin (or 5-hydroxytryptamine [5-HT]) reuptake at the terminals and cell bodies of serotonergic neurons. Escitalopram and selective serotonin reuptake inhibitors bind with high affinity to the 5-HT binding site (orthosteric site) on the transporter. This leads to antidepressant effects by increasing extracellular 5-HT levels which enhance 5-HT neurotransmission. SERT also has one or more allosteric sites, binding to which modulates activity at the orthosteric binding site but does not directly affect 5-HT reuptake by the transporter. In vitro studies have shown that through allosteric binding, escitalopram decreases its own dissociation rate from the orthosteric site on the SERT. R-citalopram, the nontherapeutic enantiomer in citalopram, is also an allosteric modulator of SERT but can inhibit the actions of escitalopram by interfering negatively with its binding. Both nonclinical studies and some clinical investigations have demonstrated the cellular, neurochemical, neuroadaptive, and neuroplastic changes induced by escitalopram with acute and chronic administration. The findings from binding, neurochemical, and neurophysiological studies may provide a mechanistic rationale for the clinical difference observed with escitalopram compared to other antidepressant therapies.

Identification of potential small molecule allosteric modulator sites on IL-1R1 ectodomain using accelerated conformational sampling method.

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Chao-Yie Yang

Full Text Available The interleukin-1 receptor (IL-1R is the founding member of the interleukin 1 receptor family which activates innate immune response by its binding to cytokines. Reports showed dysregulation of cytokine production leads to aberrant immune cells activation which contributes to auto-inflammatory disorders and diseases. Current therapeutic strategies focus on utilizing antibodies or chimeric cytokine biologics. The large protein-protein interaction interface between cytokine receptor and cytokine poses a challenge in identifying binding sites for small molecule inhibitor development. Based on the significant conformational change of IL-1R type 1 (IL-1R1 ectodomain upon binding to different ligands observed in crystal structures, we hypothesized that transient small molecule binding sites may exist when IL-1R1 undergoes conformational transition and thus suitable for inhibitor development. Here, we employed accelerated molecular dynamics (MD simulation to efficiently sample conformational space of IL-1R1 ectodomain. Representative IL-1R1 ectodomain conformations determined from the hierarchy cluster analysis were analyzed by the SiteMap program which leads to identify small molecule binding sites at the protein-protein interaction interface and allosteric modulator locations. The cosolvent mapping analysis using phenol as the probe molecule further confirms the allosteric modulator site as a binding hotspot. Eight highest ranked fragment molecules identified from in silico screening at the modulator site were evaluated by MD simulations. Four of them restricted the IL-1R1 dynamical motion to inactive conformational space. The strategy from this study, subject to in vitro experimental validation, can be useful to identify small molecule compounds targeting the allosteric modulator sites of IL-1R and prevent IL-1R from binding to cytokine by trapping IL-1R in inactive conformations.

Positive allosteric modulation of the human metabotropic glutamate receptor 4 (hmGluR4) by SIB-1893 and MPEP

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Mathiesen, Jesper Mosolff; Svendsen, Nannette; Bräuner-Osborne, Hans

2003-01-01

We have identified 2-methyl-6-(2-phenylethenyl)pyridine (SIB-1893) and 2-methyl-6-phenylethynyl pyridine hydrochloride (MPEP) as positive allosteric modulators for the hmGluR4. SIB-1893 and MPEP enhanced the potency and efficacy of L-2-amino-4-phophonobutyrate (L-AP4) in guanosine 5'-O-(3-[(35)S...

A filter-mediated communication model for design collaboration in building construction.

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Lee, Jaewook; Jeong, Yongwook; Oh, Minho; Hong, Seung Wan

2014-01-01

Multidisciplinary collaboration is an important aspect of modern engineering activities, arising from the growing complexity of artifacts whose design and construction require knowledge and skills that exceed the capacities of any one professional. However, current collaboration in the architecture, engineering, and construction industries often fails due to lack of shared understanding between different participants and limitations of their supporting tools. To achieve a high level of shared understanding, this study proposes a filter-mediated communication model. In the proposed model, participants retain their own data in the form most appropriate for their needs with domain-specific filters that transform the neutral representations into semantically rich ones, as needed by the participants. Conversely, the filters can translate semantically rich, domain-specific data into a neutral representation that can be accessed by other domain-specific filters. To validate the feasibility of the proposed model, we computationally implement the filter mechanism and apply it to a hypothetical test case. The result acknowledges that the filter mechanism can let the participants know ahead of time what will be the implications of their proposed actions, as seen from other participants' points of view.

The Grandparent-Grandchild Relationship: Implications for Models of Intergenerational Communication

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Anderson, Karen; Harwood, Jake; Hummert, Mary Lee

2005-01-01

We report two studies which examine the age stereotypes in interactions model of intergenerational communication. We investigate whether stereotyping processes mediate the effects of various predictors on communication outcomes. Support emerges for the mediating role of stereotyping. The studies also examine relational factors finding support for…

Managing Impression Formation in Computer-Mediated Communication.

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Liu, Yuliang; Ginther, Dean

2001-01-01

Offers suggestions for online instructors regarding verbal and nonverbal impression management. The recommendations should facilitate computer mediated teacher-student or manager-client interactions and help develop constructive relationships that promote learning and productivity. (EV)

Visfatin Reduces Gap Junction Mediated Cell-to-Cell Communication in Proximal Tubule-Derived Epithelial Cells

Directory of Open Access Journals (Sweden)

Claire E. Hills

2013-11-01

Full Text Available Background/Aims: In the current study we examined if the adipocytokine, visfatin, alters connexin-mediated intercellular communication in proximal tubule-derived epithelial cells. Methods: The effects of visfatin (10-200ng/mL on cell viability and cytotoxicity in HK2-cells were assessed by MTT, crystal violet and lactate dehydrogenase assays. Western blot analysis was used to confirm expression of Cx26, Cx40 and Cx43. The effect of visfatin (10-200ng/mL on TGF-β1 secretion was confirmed by ELISA, and the effects of both TGF-β1 (2-10ng/mL and visfatin (10-200ng/mL on connexin expression were assessed by western blot. Functional intercellular communication was determined using transfer of Lucifer Yellow and paired-whole cell patch clamp electrophysiology. Results: In low glucose (5mM, visfatin (10-200ng/mL did not affect membrane integrity, cytotoxicity or cell viability at 48hrs, but did evoke a concentration-dependent reduction in Cx26 and Cx43 expression. The expression of Cx40 was unaffected. At 48hrs, visfatin (10-200ng/mL increased the secretion of TGF-β1 and the visfatin-evoked changes in connexin expression were mimicked by exogenous application of the pro-fibrotic cytokine (2-10ng/ml. Visfatin reduced dye transfer between coupled cells and decreased functional conductance, with levels falling by 63% as compared to control. Although input resistance was increased following visfatin treatment by 166%, the change was not significant as compared to control. The effects of visfatin on Cx-expression and cell-coupling were blocked in the presence of a TGF-β1 specific neutralizing antibody. Conclusions: The adipocytokine visfatin selectively evoked a non-toxic reduction in connexin expression in HK2-cells. The loss in gap-junction associated proteins was mirrored by a loss in functional conductance between coupled cells. Visfatin increased TGF-β secretion and the pattern of change for connexins expression was mimicked by exogenous

Positive allosteric modulators of the α7 nicotinic acetylcholine receptor potentiate glutamate release in the prefrontal cortex of freely-moving rats

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Bortz, D M; Upton, B A; Mikkelsen, J D

2016-01-01

Positive allosteric modulators (PAMs) of α7 nicotinic acetylcholine receptors (α7nAChRs) exhibit pro-cognitive effects in animal models of schizophrenia and are targets for the discovery of cognition-enhancing drugs. However, little is known about their in vivo mechanism of action because...

Mediatization: Theorizing the Interplay Between Media, Culture, and Society

DEFF Research Database (Denmark)

Hepp, Andreas; Hjarvard, Stig; Lundby, Knut

2015-01-01

with the complex relationship between changes in media and communication on the one hand and changes in various fields of culture and society on the other. We conclude that the emergence of the concept of mediatization is part of a paradigmatic shift within media and communication research.......In response to Deacon and Stanyer’s article ‘Mediatization: Key Concept or Conceptual Bandwagon?’, we argue that they build their criticism on a simplified methodology. They mistake a media-centered approach for a media-centric one, and they do not capture how mediatization research engages...

Transmembrane α-Helix 2 and 7 Are Important for Small Molecule-Mediated Activation of the GLP-1 Receptor

DEFF Research Database (Denmark)

Underwood, Christina Rye; Møller Knudsen, Sanne; Schjellerup Wulff, Birgitte

2011-01-01

Glucagon-like peptide-1 (GLP-1) activates the GLP-1 receptor (GLP-1R), which belongs to family B of the G-protein-coupled receptors. We previously identified a selective small molecule ligand, compound 2, that acted as a full agonist and allosteric modulator of GLP-1R. In this study, the structur......Glucagon-like peptide-1 (GLP-1) activates the GLP-1 receptor (GLP-1R), which belongs to family B of the G-protein-coupled receptors. We previously identified a selective small molecule ligand, compound 2, that acted as a full agonist and allosteric modulator of GLP-1R. In this study......, the structurally related small molecule, compound 3, stimulated cAMP production from GLP-1R, but not from the homologous glucagon receptor (GluR). The receptor selectivity encouraged a chimeric receptor approach to identify domains important for compound 3-mediated activation of GLP-1R. A subsegment of the GLP-1R...... transmembrane domain containing TM2 to TM5 was sufficient to transfer compound 3 responsiveness to GluR. Therefore, divergent residues in this subsegment of GLP-1R and GluR are responsible for the receptor selectivity of compound 3. Functional analyses of other chimeric receptors suggested that the existence...

Signaling-sensitive amino acids surround the allosteric ligand binding site of the thyrotropin receptor.

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Kleinau, Gunnar; Haas, Ann-Karin; Neumann, Susanne; Worth, Catherine L; Hoyer, Inna; Furkert, Jens; Rutz, Claudia; Gershengorn, Marvin C; Schülein, Ralf; Krause, Gerd

2010-07-01

The thyrotropin receptor [thyroid-stimulating hormone receptor (TSHR)], a G-protein-coupled receptor (GPCR), is endogenously activated by thyrotropin, which binds to the extracellular region of the receptor. We previously identified a low-molecular-weight (LMW) agonist of the TSHR and predicted its allosteric binding pocket within the receptor's transmembrane domain. Because binding of the LMW agonist probably disrupts interactions or leads to formation of new interactions among amino acid residues surrounding the pocket, we tested whether mutation of residues at these positions would lead to constitutive signaling activity. Guided by molecular modeling, we performed site-directed mutagenesis of 24 amino acids in this spatial region, followed by functional characterization of the mutant receptors in terms of expression and signaling, measured as cAMP accumulation. We found that mutations V421I, Y466A, T501A, L587V, M637C, M637W, S641A, Y643F, L645V, and Y667A located in several helices exhibit constitutive activity. Of note is mutation M637W at position 6.48 in transmembrane helix 6, which has a significant effect on the interaction of the receptor with the LMW agonist. In summary, we found that a high proportion of residues in several helices surrounding the allosteric binding site of LMW ligands in the TSHR when mutated lead to constitutively active receptors. Our findings of signaling-sensitive residues in this region of the transmembrane bundle may be of general importance as this domain appears to be evolutionarily retained among GPCRs.

Computer-mediated interdisciplinary teams: theory and reality.

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Vroman, Kerryellen; Kovacich, Joann

2002-05-01

The benefit of experience, tempered with the wisdom of hindsight and 5 years of text-based, asynchronous, computer-mediated, interdisciplinary team communications, provides the energy, insights and data shared in this article. Through the theoretical lens of group dynamics and the epistemology of interdisciplinary teaming, we analyze the interactions of a virtual interdisciplinary team to provide an understanding and appreciation of collaborative interdisciplinary communication in the context of interactive technologies. Whilst interactive technologies may require new patterns of language similar to that of learning a foreign language, what is communicated in the interdisciplinary team process does not change. Most important is the recognition that virtual teams, similar to their face-to-face counterparts, undergo the same challenges of interdisciplinary teaming and group developmental processes of formation: forming, storming, norming, performing, and transforming. After examining these dynamics of communication and collaboration in the context of the virtual team, the article concludes with guidelines facilitating interdisciplinary team computer-mediated communication.

Activation of Extracellular Signal-Regulated Kinase but Not of p38 Mitogen-Activated Protein Kinase Pathways in Lymphocytes Requires Allosteric Activation of SOS

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Jun, Jesse E.; Yang, Ming; Chen, Hang; Chakraborty, Arup K.

2013-01-01

Thymocytes convert graded T cell receptor (TCR) signals into positive selection or deletion, and activation of extracellular signal-related kinase (ERK), p38, and Jun N-terminal protein kinase (JNK) mitogen-activated protein kinases (MAPKs) has been postulated to play a discriminatory role. Two families of Ras guanine nucleotide exchange factors (RasGEFs), SOS and RasGRP, activate Ras and the downstream RAF-MEK-ERK pathway. The pathways leading to lymphocyte p38 and JNK activation are less well defined. We previously described how RasGRP alone induces analog Ras-ERK activation while SOS and RasGRP cooperate to establish bimodal ERK activation. Here we employed computational modeling and biochemical experiments with model cell lines and thymocytes to show that TCR-induced ERK activation grows exponentially in thymocytes and that a W729E allosteric pocket mutant, SOS1, can only reconstitute analog ERK signaling. In agreement with RasGRP allosterically priming SOS, exponential ERK activation is severely decreased by pharmacological or genetic perturbation of the phospholipase Cγ (PLCγ)-diacylglycerol-RasGRP1 pathway. In contrast, p38 activation is not sharply thresholded and requires high-level TCR signal input. Rac and p38 activation depends on SOS1 expression but not allosteric activation. Based on computational predictions and experiments exploring whether SOS functions as a RacGEF or adaptor in Rac-p38 activation, we established that the presence of SOS1, but not its enzymatic activity, is critical for p38 activation. PMID:23589333

Department Chairs' Perceptions of the Importance of Business Communication Skills.

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Wardrope, William J.

2002-01-01

Determines business department chairs' ratings of topics typically covered in the business communication course. Indicates that department chairs perceive writing skills to be more important to business communication courses than other communication skills, such as speaking, technology-mediated communication, interpersonal communication,…

Intrateam Communication and Performance in Doubles Tennis

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Lausic, Domagoj; Tennebaum, Gershon; Eccles, David; Jeong, Allan; Johnson, Tristan

2009-01-01

Verbal and nonverbal communication is a critical mediator of performance in team sports and yet there is little extant research in sports that involves direct measures of communication. Our study explored communication within NCAA Division I female tennis doubles teams. Video and audio recordings of players during doubles tennis matches captured…

Investigating the Effects of Mass Media Exposure on the Uptake of Preventive Measures by Hong Kong Residents during the 2015 MERS Outbreak: The Mediating Role of Interpersonal Communication and the Perception of Concern.

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Ludolph, Ramona; Schulz, Peter J; Chen, Ling

2018-01-01

In 2015, South Korea experienced the largest outbreak to date of the Middle East Respiratory Syndrome (MERS-CoV) outside the Middle East. Fears related to a potential spread of the disease led to an increased alert level as well as heightened media coverage in the neighboring Hong Kong. A cross-sectional survey (N = 533) among residents of Hong Kong was conducted to assess the relationships between the effects of outbreak-related mass media coverage, interpersonal communication, the perceived level of concern in one's close environment, and the uptake of preventive measures. A serial multiple mediator model finds that interpersonal communication and higher perceived concern indirectly influence the effects of media coverage on the engagement in preventive actions. These results expand previous research on the mediating role of interpersonal communication and support assumptions about a modified two-step flow of communication in the context of a public health emergency.

Designing for Networked Communications

DEFF Research Database (Denmark)

Designing for Networked Communications: Strategies and Development explains how to plan, use, and understand the products and the dynamic social processes and tasks some of the most vital innovations in the knowledge society depend upon– social as well as technological. Focusing on various forms...... of design, implementation and integration of computer mediated communication, this book bridges the academic fields of computer science and communication studies. Designing for Networked Communications: Strategies and Development uses an interdisciplinary approach, and presents results from recent...... and important research in a variety of forms for networked communications. A constructive and critical view of the interplay between the new electronic and the more conventional modes of communication are utilized, while studies of organizational work practices demonstrate that the use of new technologies...

Parent-mediated communication-focused treatment in children with autism (PACT): a randomised controlled trial.

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Green, Jonathan; Charman, Tony; McConachie, Helen; Aldred, Catherine; Slonims, Vicky; Howlin, Pat; Le Couteur, Ann; Leadbitter, Kathy; Hudry, Kristelle; Byford, Sarah; Barrett, Barbara; Temple, Kathryn; Macdonald, Wendy; Pickles, Andrew

2010-06-19

Results of small trials suggest that early interventions for social communication are effective for the treatment of autism in children. We therefore investigated the efficacy of such an intervention in a larger trial. Children with core autism (aged 2 years to 4 years and 11 months) were randomly assigned in a one-to-one ratio to a parent-mediated communication-focused (Preschool Autism Communication Trial [PACT]) intervention or treatment as usual at three specialist centres in the UK. Those assigned to PACT were also given treatment as usual. Randomisation was by use of minimisation of probability in the marginal distribution of treatment centre, age (42 months), and autism severity (Autism Diagnostic Observation Schedule-Generic [ADOS-G] algorithm score 12-17 or 18-24). Primary outcome was severity of autism symptoms (a total score of social communication algorithm items from ADOS-G, higher score indicating greater severity) at 13 months. Complementary secondary outcomes were measures of parent-child interaction, child language, and adaptive functioning in school. Analysis was by intention to treat. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN58133827. 152 children were recruited. 77 were assigned to PACT (London [n=26], Manchester [n=26], and Newcastle [n=25]); and 75 to treatment as usual (London [n=26], Manchester [n=26], and Newcastle [n=23]). At the 13-month endpoint, the severity of symptoms was reduced by 3.9 points (SD 4.7) on the ADOS-G algorithm in the group assigned to PACT, and 2.9 (3.9) in the group assigned to treatment as usual, representing a between-group effect size of -0.24 (95% CI -0.59 to 0.11), after adjustment for centre, sex, socioeconomic status, age, and verbal and non-verbal abilities. Treatment effect was positive for parental synchronous response to child (1.22, 0.85 to 1.59), child initiations with parent (0.41, 0.08 to 0.74), and for parent-child shared attention (0.33, -0.02 to

The allosteric HIV-1 integrase inhibitor BI-D affects virion maturation but does not influence packaging of a functional RNA genome

NARCIS (Netherlands)

van Bel, Nikki; van der Velden, Yme; Bonnard, Damien; Le Rouzic, Erwann; Das, Atze T.; Benarous, Richard; Berkhout, Ben

2014-01-01

The viral integrase (IN) is an essential protein for HIV-1 replication. IN inserts the viral dsDNA into the host chromosome, thereby aided by the cellular co-factor LEDGF/p75. Recently a new class of integrase inhibitors was described: allosteric IN inhibitors (ALLINIs). Although designed to

Probe-Dependent Negative Allosteric Modulators of the Long-Chain Free Fatty Acid Receptor FFA4

DEFF Research Database (Denmark)

Watterson, Kenneth R; Hansen, Steffen V F; Hudson, Brian D

2017-01-01

High-affinity and selective antagonists that are able to block the actions of both endogenous and synthetic agonists of G protein-coupled receptors are integral to analysis of receptor function and to support suggestions of therapeutic potential. Although there is great interest in the potential...... of endogenous and synthetic agonists, clear agonist probe dependence in the nature of allosteric modulation was apparent. Although AH-7614 did not antagonize the second long-chain free fatty acid receptor, free fatty acid receptor 1, the simple chemical structure of AH-7614 containing features found in many...

Characterization of the allosteric binding pocket of human liver fructose-1,6-bisphosphatase by protein crystallography and inhibitor activity studies.

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Iversen, L F; Brzozowski, M; Hastrup, S; Hubbard, R; Kastrup, J S; Larsen, I K; Naerum, L; Nørskov-Lauridsen, L; Rasmussen, P B; Thim, L; Wiberg, F C; Lundgren, K

1997-05-01

The structures of three complexes of human fructose-1,6-bisphosphatase (FB) with the allosteric inhibitor AMP and two AMP analogues have been determined and all fully refined. The data used for structure determination were collected at cryogenic temperature (110 K), and with the use of synchrotron radiation. The structures reveal a common mode of binding for AMP and formycine monophosphate (FMP). 5-Amino-4-carboxamido-1 beta-D-5-phosphate-ribofuranosyl-1H-imidazole (AICAR-P) shows an unexpected mode of binding to FB, different from that of the other two ligands. The imidazole ring of AICAR-P is rotated 180 degrees compared to the AMP and FMP bases. This rotation results in a slightly different hydrogen bonding pattern and minor changes in the water structure in the binding pocket. Common features of binding are seen for the ribose and phosphate moieties of all three compounds. Although binding in a different mode, AICAR-P is still capable of making all the important interactions with the residues building the allosteric binding pocket. The IC50 values of AMP, FMP, and AICAR-P were determined to be 1.7, 1.4, and 20.9 microM, respectively. Thus, the approximately 10 times lower potency of AICAR-P is difficult to explain solely from the variations observed in the binding pocket. Only one water molecule in the allosteric binding pocket was found to be conserved in all four subunits in all three structures. This water molecule coordinates to a phosphate oxygen atom and the N7 atom of the AMP molecule, and to similarly situated atoms in the FMP and AICAR-P complexes. This implies an important role of the conserved water molecule in binding of the ligand.

Vestigialization of an Allosteric Switch: Genetic and Structural Mechanisms for the Evolution of Constitutive Activity in a Steroid Hormone Receptor

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Bridgham, Jamie T.; Keay, June; Ortlund, Eric A.; Thornton, Joseph W.

2014-01-01

An important goal in molecular evolution is to understand the genetic and physical mechanisms by which protein functions evolve and, in turn, to characterize how a protein's physical architecture influences its evolution. Here we dissect the mechanisms for an evolutionary shift in function in the mollusk ortholog of the steroid hormone receptors (SRs), a family of biologically essential transcription factors. In vertebrates, the activity of SRs allosterically depends on binding a hormonal ligand; in mollusks, however, the SR ortholog (called ER, because of high sequence similarity to vertebrate estrogen receptors) activates transcription in the absence of ligand and does not respond to steroid hormones. To understand how this shift in regulation evolved, we combined evolutionary, structural, and functional analyses. We first determined the X-ray crystal structure of the ER of the Pacific oyster Crassostrea gigas (CgER), and found that its ligand pocket is filled with bulky residues that prevent ligand occupancy. To understand the genetic basis for the evolution of mollusk ERs' unique functions, we resurrected an ancient SR progenitor and characterized the effect of historical amino acid replacements on its functions. We found that reintroducing just two ancient replacements from the lineage leading to mollusk ERs recapitulates the evolution of full constitutive activity and the loss of ligand activation. These substitutions stabilize interactions among key helices, causing the allosteric switch to become “stuck” in the active conformation and making activation independent of ligand binding. Subsequent changes filled the ligand pocket without further affecting activity; by degrading the allosteric switch, these substitutions vestigialized elements of the protein's architecture required for ligand regulation and made reversal to the ancestral function more complex. These findings show how the physical architecture of allostery enabled a few large-effect mutations

Vestigialization of an allosteric switch: genetic and structural mechanisms for the evolution of constitutive activity in a steroid hormone receptor.

Directory of Open Access Journals (Sweden)

Jamie T Bridgham

2014-01-01

Full Text Available An important goal in molecular evolution is to understand the genetic and physical mechanisms by which protein functions evolve and, in turn, to characterize how a protein's physical architecture influences its evolution. Here we dissect the mechanisms for an evolutionary shift in function in the mollusk ortholog of the steroid hormone receptors (SRs, a family of biologically essential transcription factors. In vertebrates, the activity of SRs allosterically depends on binding a hormonal ligand; in mollusks, however, the SR ortholog (called ER, because of high sequence similarity to vertebrate estrogen receptors activates transcription in the absence of ligand and does not respond to steroid hormones. To understand how this shift in regulation evolved, we combined evolutionary, structural, and functional analyses. We first determined the X-ray crystal structure of the ER of the Pacific oyster Crassostrea gigas (CgER, and found that its ligand pocket is filled with bulky residues that prevent ligand occupancy. To understand the genetic basis for the evolution of mollusk ERs' unique functions, we resurrected an ancient SR progenitor and characterized the effect of historical amino acid replacements on its functions. We found that reintroducing just two ancient replacements from the lineage leading to mollusk ERs recapitulates the evolution of full constitutive activity and the loss of ligand activation. These substitutions stabilize interactions among key helices, causing the allosteric switch to become "stuck" in the active conformation and making activation independent of ligand binding. Subsequent changes filled the ligand pocket without further affecting activity; by degrading the allosteric switch, these substitutions vestigialized elements of the protein's architecture required for ligand regulation and made reversal to the ancestral function more complex. These findings show how the physical architecture of allostery enabled a few large

The Role of Artefacts in Presence Mediation

NARCIS (Netherlands)

Vyas, Dhaval; Tzovaras, D

2007-01-01

Approaches to support computer mediated communication (CMC) have predominantly relied on the face-to-face communication paradigm. However, interaction and coordination can also be supported by different technological artefacts. In fact, most researches [1, 2, 3] related to ethnomethodology have

Corporate Social Responsibility, Reputation, and Moral Communication

DEFF Research Database (Denmark)

Schultz, Friederike

2013-01-01

and critically discusses insights from instrumental perspectives and from political-normative perspectives (legitimacy, business ethics). It alternatively develops a constructivist communication view on CSR, building on the “communication constitutes organizations” perspective and a non-dualist turn. It argues...... that CSR is a symbolically mediated, communicative event, which, based on the underlying dynamics of moral communication, does not simply produce reputation, but also result in dysfunctional effects....

The Influence of Green Viral Communications on Green Purchase Intentions: The Mediating Role of Consumers’ Susceptibility to Interpersonal Influences

Directory of Open Access Journals (Sweden)

Sheng-Hsiung Chang

2015-04-01

Full Text Available This paper aims to incorporate the diffusion of innovation theory and conformity theory to explain consumers’ green purchase intentions. To this end, a conceptual model has been proposed and subjected to empirical verification with the use of a survey method. Using a sample of Taiwanese consumers who had the actual purchase experience of green detergents, this study employed structural equation modeling to verify the hypothesis proposed. The empirical results suggested that green viral communication was positively related to normative interpersonal influence, informational interpersonal influence and green purchase intention. Informational interpersonal influence also had a positive impact on green purchase intention. However, the relationship between consumer’s normative interpersonal influence and green purchase intention was not supported. Thus, this study concludes that green marketers must strengthen their green viral communications skills to enhance consumers’ purchase intentions. In addition, this study also contributes to the literature by stating that consumers’ susceptibility to informational interpersonal relationships is an important mediator in the green viral communication and green purchase intentions relationship. This study discusses implications of the findings and research limitations at the end of the paper.

Use Patterns of Visual Cues in Computer-Mediated Communication

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Bolliger, Doris U.

2009-01-01

Communication in the virtual environment can be challenging for participants because it lacks physical presence and nonverbal elements. Participants may have difficulties expressing their intentions and emotions in a primarily text-based course. Therefore, the use of visual communication elements such as pictographic and typographic marks can be…

Mediation as Problem-Solving Scene in the Light of PTC

Directory of Open Access Journals (Sweden)

Viktor Németh

2014-05-01

Full Text Available Mediation does not only mean a specific procedure or protocol but the related attitude, mindset as well. This perspective gives opportunity to demonstrate the problem in a different way than previously. In the present study, the Participatory Theory of Communication (PTC appears as a framework which makes the communication of participants of the mediation interpretable and transparent.

Improving Undergraduates' Critique via Computer Mediated Communication

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Mohamad, Maslawati; Musa, Faridah; Amin, Maryam Mohamed; Mufti, Norlaila; Latiff, Rozmel Abdul; Sallihuddin, Nani Rahayu

2014-01-01

Our current university students, labeled as "Generation Y" or Millennials, are different from previous generations due to wide exposure to media. Being technologically savvy, they are accustomed to Internet for information and social media for socializing. In line with this current trend, teaching through computer mediated communication…

Allosteric mechanism controls traffic in the chaperone/usher pathway.

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Di Yu, Xiao; Dubnovitsky, Anatoly; Pudney, Alex F; Macintyre, Sheila; Knight, Stefan D; Zavialov, Anton V

2012-11-07

Many virulence organelles of Gram-negative bacterial pathogens are assembled via the chaperone/usher pathway. The chaperone transports organelle subunits across the periplasm to the outer membrane usher, where they are released and incorporated into growing fibers. Here, we elucidate the mechanism of the usher-targeting step in assembly of the Yersinia pestis F1 capsule at the atomic level. The usher interacts almost exclusively with the chaperone in the chaperone:subunit complex. In free chaperone, a pair of conserved proline residues at the beginning of the subunit-binding loop form a "proline lock" that occludes the usher-binding surface and blocks usher binding. Binding of the subunit to the chaperone rotates the proline lock away from the usher-binding surface, allowing the chaperone-subunit complex to bind to the usher. We show that the proline lock exists in other chaperone/usher systems and represents a general allosteric mechanism for selective targeting of chaperone:subunit complexes to the usher and for release and recycling of the free chaperone. Copyright © 2012 Elsevier Ltd. All rights reserved.

Theoretical Analysis of Allosteric and Operator Binding for Cyclic-AMP Receptor Protein Mutants

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Einav, Tal; Duque, Julia; Phillips, Rob

2018-02-01

Allosteric transcription factors undergo binding events both at their inducer binding sites as well as at distinct DNA binding domains, and it is often difficult to disentangle the structural and functional consequences of these two classes of interactions. In this work, we compare the ability of two statistical mechanical models - the Monod-Wyman-Changeux (MWC) and the Koshland-N\\'emethy-Filmer (KNF) models of protein conformational change - to characterize the multi-step activation mechanism of the broadly acting cyclic-AMP receptor protein (CRP). We first consider the allosteric transition resulting from cyclic-AMP binding to CRP, then analyze how CRP binds to its operator, and finally investigate the ability of CRP to activate gene expression. In light of these models, we examine data from a beautiful recent experiment that created a single-chain version of the CRP homodimer, thereby enabling each subunit to be mutated separately. Using this construct, six mutants were created using all possible combinations of the wild type subunit, a D53H mutant subunit, and an S62F mutant subunit. We demonstrate that both the MWC and KNF models can explain the behavior of all six mutants using a small, self-consistent set of parameters. In comparing the results, we find that the MWC model slightly outperforms the KNF model in the quality of its fits, but more importantly the parameters inferred by the MWC model are more in line with structural knowledge of CRP. In addition, we discuss how the conceptual framework developed here for CRP enables us to not merely analyze data retrospectively, but has the predictive power to determine how combinations of mutations will interact, how double mutants will behave, and how each construct would regulate gene expression.

Positive versus negative modulation of different endogenous chemokines for CC-chemokine receptor 1 by small molecule agonists through allosteric versus orthosteric binding

DEFF Research Database (Denmark)

Jensen, Pia C; Thiele, Stefanie; Ulven, Trond

2008-01-01

7 transmembrane-spanning (7TM) chemokine receptors having multiple endogenous ligands offer special opportunities to understand the molecular basis for allosteric mechanisms. Thus, CC-chemokine receptor 1 (CCR1) binds CC-chemokine 3 and 5 (CCL3 and CCL5) with K(d) values of 7.3 and 0.16 nm......5 and not CCL3 activation is affected by substitutions in the main ligand binding pocket including the conserved GluVII:06 anchor point. A series of metal ion chelator complexes were found to act as full agonists on CCR1 and to be critically affected by the same substitutions in the main ligand...... binding pocket as CCL5 but not by mutations in the extracellular domain. In agreement with the overlapping binding sites, the small non-peptide agonists displaced radiolabeled CCL5 with high affinity. Interestingly, the same compounds acted as allosteric enhancers of the binding of CCL3, with which...

Cell-cell communication in the kidney microcirculation

DEFF Research Database (Denmark)

Sørensen, Charlotte Mehlin; von Holstein-Rathlou, Niels-Henrik

2012-01-01

the postglomerular vasculature. Cxs form gap junctions between neighboring cells, and as in other organ systems, the major function of Cxs in the kidney appears to be mediation of intercellular communication. Cxs may also form hemichannels that allow cellular secretion of signaling molecules like ATP, and thereby...... mediate paracrine signaling. Renal Cxs facilitate vascular conduction, juxtaglomerlar apparatus calcium signaling, and enable ECs and VSMCs to communicate. Thus, current research suggests multiple roles for Cxs in important regulatory mechanisms within the kidney, including the renin-angiotensin system...

Web-Mediated Communication: in Search of Togetherness

NARCIS (Netherlands)

P.S. Cesar Garcia (Pablo Santiago); D.C.A. Bulterman (Dick); R.L. Guimarães (Rodrigo); I. Kegel

2010-01-01

htmlabstractThis paper introduces a community-based video sharing environment to support asynchronous communication among heterogeneous participants within a restricted social community. Unlike other community sharing efforts, our work is predicated on the desire to strengthen existing strong ties

Effects of intraperitoneal administration of the GABAB receptor positive allosteric modulator 2,6-di tert-butyl-4-(2-hydroxy-2,2-dimethyl-propyl)-phenol (CGP7930) on food intake in non-deprived rats.

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Ebenezer, Ivor S

2012-09-05

γ-Aminobutyric acid-(B) (GABA(B)) receptor positive allosteric modulators (PAMs) act on an allosteric site on the GABA(B) receptor to potentiate the effects of GABA and GABA(B) receptor agonists. It has previously been demonstrated that the GABA(B) receptor agonist baclofen increases food intake in non-deprived rats. The aim of this study was to investigate whether the GABA(B) receptor PAM 2,6-di tert-butyl-4-(2-hydroxy-2,2-dimethyl-propyl)-phenol (CGP7930) would (i) increase food intake, and (ii) potentiate the hyperphagic effects of baclofen in rats. In Experiment 1, the effects of intraperitoneal (i.p.) administration of CGP7930 (1, 6 and 12 mg/kg) was investigated on food intake in non-deprived male Wistar rats. The 12 mg/kg dose of CGP7930 significantly increased cumulative food intake 30, 60 and 120 min (PGABA and GABA(B) receptor agonists by allosteric modulation of the GABA(B) receptor. Copyright © 2012 Elsevier B.V. All rights reserved.

3β-Methyl-Neurosteroid Analogs are Preferential Positive Allosteric Modulators and Direct Activators of Extrasynaptic δGABA-A Receptors in the Hippocampus Dentate Gyrus Subfield.

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Chuang, Shu-Hui; Reddy, Doodipala Samba

2018-03-30

Neurosteroids are powerful modulators of GABA-A receptors. Ganaxolone (3α-hydroxy-3β-methyl-5α-pregnan-20-one, GX) and synthetic analogs of the neurosteroid allopregnanolone (AP) are designed to treat epilepsy and related conditions. However, their precise mechanism of action in native neurons remains unclear. Here, we sought to determine the mode of action of GX and its analogs at GABA-A receptors in native hippocampal neurons by analyzing extrasynaptic receptor-mediated tonic currents and synaptic receptor-mediated phasic currents. Concentration-response profiles of GX were determined in two cell types: δ-containing dentate gyrus granule cells (DGGCs) and γ2-containing CA1 pyramidal cells (CA1PCs). GX produced significantly greater potentiation of the GABA-A receptor-activated chloride currents in DGGCs (500%) than CA1PCs (200%). In the absence of GABA, GX evoked 2-fold greater inward currents in DGGCs than CA1PCs, which were 2-fold greater than AP within DGGCs. In hippocampus slices, GX potentiated and directly activated tonic currents in DGGCs. These responses were significantly diminished in DGGCs from δ-subunit knockout (δKO) mice, confirming GX's selectivity for δGABA-A receptors. Like AP, GX potentiation of tonic currents was prevented by protein kinase C inhibition. Furthermore, GX's protection against hippocampus kindled seizures was significantly diminished in δKO mice. GX analogs exhibited greater potency and efficacy than GX on δGABA-A receptor-mediated tonic inhibition. In summary, these results provide strong evidence that GX and its analogs are preferential allosteric modulators and direct activators of extrasynaptic δGABA-A receptors regulating network inhibition and seizures in the dentate gyrus. Therefore, these findings provide a mechanistic rationale for the clinical use of synthetic neurosteroids in epilepsy and seizure disorders. The American Society for Pharmacology and Experimental Therapeutics.

Cyclophilin40 isomerase activity is regulated by a temperature-dependent allosteric interaction with Hsp90.

Science.gov (United States)

Blackburn, Elizabeth A; Wear, Martin A; Landré, Vivian; Narayan, Vikram; Ning, Jia; Erman, Burak; Ball, Kathryn L; Walkinshaw, Malcolm D

2015-09-01

Cyclophilin 40 (Cyp40) comprises an N-terminal cyclophilin domain with peptidyl-prolyl isomerase (PPIase) activity and a C-terminal tetratricopeptide repeat (TPR) domain that binds to the C-terminal-EEVD sequence common to both heat shock protein 70 (Hsp70) and Hsp90. We show in the present study that binding of peptides containing the MEEVD motif reduces the PPIase activity by ∼30%. CD and fluorescence assays show that the TPR domain is less stable than the cyclophilin domain and is stabilized by peptide binding. Isothermal titration calorimetry (ITC) shows that the affinity for the-MEEVD peptide is temperature sensitive in the physiological temperature range. Results from these biophysical studies fit with the MD simulations of the apo and holo (peptide-bound) structures which show a significant reduction in root mean square (RMS) fluctuation in both TPR and cyclophilin domains when-MEEVD is bound. The MD simulations of the apo-protein also highlight strong anti-correlated motions between residues around the PPIase-active site and a band of residues running across four of the seven helices in the TPR domain. Peptide binding leads to a distortion in the shape of the active site and a significant reduction in these strongly anti-correlated motions, providing an explanation for the allosteric effect of ligand binding and loss of PPIase activity. Together the experimental and MD results suggest that on heat shock, dissociation of Cyp40 from complexes mediated by the TPR domain leads to an increased pool of free Cyp40 capable of acting as an isomerase/chaperone in conditions of cellular stress. © 2015 Authors.

Hot or cold: is communicating anger or threats more effective in negotiation?

Science.gov (United States)

Sinaceur, Marwan; Van Kleef, Gerben A; Neale, Margaret A; Adam, Hajo; Haag, Christophe

2011-09-01

Is communicating anger or threats more effective in eliciting concessions in negotiation? Recent research has emphasized the effectiveness of anger communication, an emotional strategy. In this article, we argue that anger communication conveys an implied threat, and we document that issuing threats is a more effective negotiation strategy than communicating anger. In 3 computer-mediated negotiation experiments, participants received either angry or threatening messages from a simulated counterpart. Experiment 1 showed that perceptions of threat mediated the effect of anger (vs. a control) on concessions. Experiment 2 showed that (a) threat communication elicited greater concessions than anger communication and (b) poise (being confident and in control of one's own feelings and decisions) ascribed to the counterpart mediated the positive effect of threat compared to anger on concessions. Experiment 3 replicated this positive effect of threat over anger when recipients had an attractive alternative to a negotiated agreement. These findings qualify previous research on anger communication in negotiation. Implications for the understanding of emotion and negotiation are discussed. PsycINFO Database Record (c) 2011 APA, all rights reserved

Covalent Allosteric Inactivation of Protein Tyrosine Phosphatase 1B (PTP1B) by an Inhibitor-Electrophile Conjugate.

Science.gov (United States)

Punthasee, Puminan; Laciak, Adrian R; Cummings, Andrea H; Ruddraraju, Kasi Viswanatharaju; Lewis, Sarah M; Hillebrand, Roman; Singh, Harkewal; Tanner, John J; Gates, Kent S

2017-04-11

Protein tyrosine phosphatase 1B (PTP1B) is a validated drug target, but it has proven difficult to develop medicinally useful, reversible inhibitors of this enzyme. Here we explored covalent strategies for the inactivation of PTP1B using a conjugate composed of an active site-directed 5-aryl-1,2,5-thiadiazolidin-3-one 1,1-dioxide inhibitor connected via a short linker to an electrophilic α-bromoacetamide moiety. Inhibitor-electrophile conjugate 5a caused time-dependent loss of PTP1B activity consistent with a covalent inactivation mechanism. The inactivation occurred with a second-order rate constant of (1.7 ± 0.3) × 10 2 M -1 min -1 . Mass spectrometric analysis of the inactivated enzyme indicated that the primary site of modification was C121, a residue distant from the active site. Previous work provided evidence that covalent modification of the allosteric residue C121 can cause inactivation of PTP1B [Hansen, S. K., Cancilla, M. T., Shiau, T. P., Kung, J., Chen, T., and Erlanson, D. A. (2005) Biochemistry 44, 7704-7712]. Overall, our results are consistent with an unusual enzyme inactivation process in which noncovalent binding of the inhibitor-electrophile conjugate to the active site of PTP1B protects the nucleophilic catalytic C215 residue from covalent modification, thus allowing inactivation of the enzyme via selective modification of allosteric residue C121.

Communication self-efficacy in optometry: the mediating role of mindfulness

OpenAIRE

Sundling, Vibeke; van Dulmen, Sandra; Eide, Hilde

2016-01-01

The aim of this study was to examine the relationship between optometry students’ communication self-efficacy and their level of mindfulness and empathy. The study had a cross-sectional design. The sample included qualified optometrists in their first year of the Masters’ degree programme. The students reported level of communication self-efficacy, empathy and mindfulness by responding to three questionnaires: Ammentorp’s Clear-Cut Communication with Patients, Jefferson Scale of Empathy, and ...

Communication, Reasoning, and Planned Behaviors: Unveiling the Effect of Interactive Communication in an Anti-Smoking Social Media Campaign.

Science.gov (United States)

Namkoong, Kang; Nah, Seungahn; Record, Rachael A; Van Stee, Stephanie K

2017-01-01

This study examines direct and indirect effects of interactive communication in an antismoking social media campaign. To that end, we pose a multitheoretical framework that integrates communication mediation models and the Theory of Planned Behavior. To test the theorized model, we conducted an experiment using a two-group pretest-posttest design. Participants (N = 201) were randomly assigned into two experimental conditions: "campaign message reception only" as a control group and "message reception and social interaction" as a treatment group, in which the participants contributed to the antismoking campaign by posting their own campaign ideas and information they found through mediated and interpersonal communication. The findings show that interactive communication catalyzes the participants' information searching behaviors through diverse communication channels. In turn, increased media use plays a crucial role in changing their attitudes and perceived social norms about smoking behaviors, and eventually reducing smoking intention. This study affirms that the theory of planned behavior is effective in predicting behavioral intention and demonstrates the usefulness of a multitheoretical approach in interactive campaign research on social media.

Mediatization: a concept, multiple voices

Directory of Open Access Journals (Sweden)

Pedro Gilberto GOMES

2016-12-01

Full Text Available Mediatization has become increasingly a key concept, fundamental, essential to describe the present and the history of media and communicative change taking place. Thus, it became part of a whole, one can not see them as a separate sphere. In this perspective, the media coverage is used as a concept to describe the process of expansion of the different technical means and consider the interrelationships between the communicative change, means and sociocultural change. However, although many researchers use the concept of mediatization, each gives you the meaning that best suits your needs. Thus, the concept of media coverage is treated with multiple voices. This paper discusses this problem and present a preliminary pre-position on the matter.

Gs protein peptidomimetics as allosteric modulators of the β2-adrenergic receptor

DEFF Research Database (Denmark)

Boyhus, Lotte Emilie; Danielsen, Mia; Bengtson, Nina Smidt

2018-01-01

A series of Gs protein peptidomimetics were designed and synthesised based on the published X-ray crystal structure of the active state β2-Adrenergic receptor (β2AR) in complex with the Gs protein (PDB 3SN6). We hypothesised that such peptidomimetics may function as allosteric modulators...... that target the intracellular Gs protein binding site of the β2AR. Peptidomimetics were designed to mimic the 15 residue C-Terminal α-helix of the Gs protein and were pre-organised in a helical conformation by (i, i + 4)-stapling using copper catalysed azide alkyne cycloaddition. Linear and stapled...... be able to compete with the native Gs protein for the intracellular binding site to block ISO-induced cAMP formation, but are unable to stabilise an active-like receptor conformation....

Design and optimization of selective azaindole amide M1 positive allosteric modulators.

Science.gov (United States)

Davoren, Jennifer E; O'Neil, Steven V; Anderson, Dennis P; Brodney, Michael A; Chenard, Lois; Dlugolenski, Keith; Edgerton, Jeremy R; Green, Michael; Garnsey, Michelle; Grimwood, Sarah; Harris, Anthony R; Kauffman, Gregory W; LaChapelle, Erik; Lazzaro, John T; Lee, Che-Wah; Lotarski, Susan M; Nason, Deane M; Obach, R Scott; Reinhart, Veronica; Salomon-Ferrer, Romelia; Steyn, Stefanus J; Webb, Damien; Yan, Jiangli; Zhang, Lei

2016-01-15

Selective activation of the M1 receptor via a positive allosteric modulator (PAM) is a new approach for the treatment of the cognitive impairments associated with schizophrenia and Alzheimer's disease. A novel series of azaindole amides and their key pharmacophore elements are described. The nitrogen of the azaindole core is a key design element as it forms an intramolecular hydrogen bond with the amide N-H thus reinforcing the bioactive conformation predicted by published SAR and our homology model. Representative compound 25 is a potent and selective M1 PAM that has well aligned physicochemical properties, adequate brain penetration and pharmacokinetic (PK) properties, and is active in vivo. These favorable properties indicate that this series possesses suitable qualities for further development and studies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Positive allosteric modulation of TRPV1 as a novel analgesic mechanism

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Lebovitz Evan E

2012-09-01

Full Text Available Abstract Background The prevalence of long-term opiate use in treating chronic non-cancer pain is increasing, and prescription opioid abuse and dependence are a major public health concern. To explore alternatives to opioid-based analgesia, the present study investigates a novel allosteric pharmacological approach operating through the cation channel TRPV1. This channel is highly expressed in subpopulations of primary afferent unmyelinated C- and lightly-myelinated Aδ-fibers that detect low and high rates of noxious heating, respectively, and it is also activated by vanilloid agonists and low pH. Sufficient doses of exogenous vanilloid agonists, such as capsaicin or resiniferatoxin, can inactivate/deactivate primary afferent endings due to calcium overload, and we hypothesized that positive allosteric modulation of agonist-activated TRPV1 could produce a selective, temporary inactivation of nociceptive nerve terminals in vivo. We previously identified MRS1477, a 1,4-dihydropyridine that potentiates vanilloid and pH activation of TRPV1 in vitro, but displays no detectable intrinsic agonist activity of its own. To study the in vivo effects of MRS1477, we injected the hind paws of rats with a non-deactivating dose of capsaicin, MRS1477, or the combination. An infrared diode laser was used to stimulate TRPV1-expressing nerve terminals and the latency and intensity of paw withdrawal responses were recorded. qRT-PCR and immunohistochemistry were performed on dorsal root ganglia to examine changes in gene expression and the cellular specificity of such changes following treatment. Results Withdrawal responses of the capsaicin-only or MRS1477-only treated paws were not significantly different from the untreated, contralateral paws. However, rats treated with the combination of capsaicin and MRS1477 exhibited increased withdrawal latency and decreased response intensity consistent with agonist potentiation and inactivation or lesion of TRPV1-containing

Producing Irony in Adolescence: A Comparison Between Face-to-Face and Computer-Mediated Communication

Directory of Open Access Journals (Sweden)

Aguert Marc

2016-12-01

Full Text Available The literature suggests that irony production expands in the developmental period of adolescence. We aimed to test this hypothesis by investigating two channels: face-to-face and computer-mediated communication (CMC. Corpora were collected by asking seventh and 11th graders to freely discuss some general topics (e.g., music, either face-to-face or on online forums. Results showed that 6.2% of the 11th graders’ productions were ironic utterances, compared with just 2.5% of the seventh graders’ productions, confirming the major development of irony production in adolescence. Results also showed that adolescents produced more ironic utterances in CMC than face-to-face. The analysis suggested that irony use is a strategy for increasing in-group solidarity and compensating for the distance intrinsic to CMC, as it was mostly inclusive and well-marked on forums. The present study also confirmed previous studies showing that irony is compatible with CMC.

Changes of cooperativity between N-methylscopolamine and allosteric modulators alcuronium and gallamine induced by mutations of external loops of muscarinic M(3) receptors

Czech Academy of Sciences Publication Activity Database

Krejčí, Alena; Tuček, Stanislav

2001-01-01

Roč. 60, č. 4 (2001), s. 761-767 ISSN 0026-895X R&D Projects: GA ČR GA309/99/0214 Institutional research plan: CEZ:AV0Z5011922 Keywords : muscarinic receptors * allosteric modulators Subject RIV: FH - Neurology Impact factor: 5.297, year: 2001

Technological, mediatic and cultural hybridisation: Cultural mediations in the context of globalisation

Directory of Open Access Journals (Sweden)

Laan Mendes de Barros

2009-12-01

Full Text Available We live in a context of borders that are dissolving in many senses, of the convergence and hybridisation of technologies, mass media and cultures. The context is the resizing of practical time, of movements and links between the local and the global. In these times of interculturality, communication plays a very important role; not so much in its technological media dimension, but particularly in the dynamics of cultural mediations that are dividing off from mediatised relations. This article aims to reflect on the transformations in present-day communication processes, marked by strong movements of hybridisation, as well as examining how to consider interculturality in the context of cultural mediations, based on dialogue between Latin American and French authors. Also, using media material, the article presents illustrations of the Brazilian cultural scene, which is marked by a long history of hybridisation that is filled with intercultural dynamics.

New Media Technology in Developing Effective Organizational Internal Communication

OpenAIRE

Kholisoh, Nur; Sulastri, Ria

2017-01-01

The article was intended to investigate various benefits of Whatsapp Messenger application for an effective intenal communication in PT Euro Management Indonesia. In addition, this research also aimed to map the organizational internal communication pattern through the use of Whatsapp Messenger application. The research used theories of organizaional communication, new media communication pattern, and computer mediated communication (CMC). Moreover, paradigm used in the research was construct...

RELATIONSHIPS AND COMMUNICATION NETWORKS

OpenAIRE

Stefan VLADUTESCU

2012-01-01

The main feature of the present situation regarding communication is the impregnation of the social with technology. Computer-mediated communication systems has led to the crystallization of a strong specific interactions. This article describes how human relationships constitues the ontological pillar of society and social relations form the axis irradiance of sociology. Overall, as social agents in social space, people come in a variety of social relationships. Thus, a distinct note of the ...

Peer-to-peer communication, cancer prevention, and the internet

Science.gov (United States)

Ancker, Jessica S.; Carpenter, Kristen M.; Greene, Paul; Hoffmann, Randi; Kukafka, Rita; Marlow, Laura A.V.; Prigerson, Holly G.; Quillin, John M.

2013-01-01

Online communication among patients and consumers through support groups, discussion boards, and knowledge resources is becoming more common. In this paper, we discuss key methods through which such web-based peer-to-peer communication may affect health promotion and disease prevention behavior (exchanges of information, emotional and instrumental support, and establishment of group norms and models). We also discuss several theoretical models for studying online peer communication, including social theory, health communication models, and health behavior models. Although online peer communication about health and disease is very common, research evaluating effects on health behaviors, mediators, and outcomes is still relatively sparse. We suggest that future research in this field should include formative evaluation and studies of effects on mediators of behavior change, behaviors, and outcomes. It will also be important to examine spontaneously emerging peer communication efforts to see how they can be integrated with theory-based efforts initiated by researchers. PMID:19449267

Language Learning Effects through the Integration of Synchronous Online Communication: The Case of Video Communication and Second Life

Science.gov (United States)

Canto, Silvia; Jauregi Ondarra, Kristi

2017-01-01

This article attempts to shed some light on the possible learning benefits for language acquisition and intercultural development of authentic social interaction with expert peers through computer mediated communication (CMC) tools. The environments used in this study are video communication and the 3D virtual world "Second Life." For…

The practice of mediation to resolve clinical, bioethical, and medical malpractice disputes.

Science.gov (United States)

Lee, Danny W H; Lai, Paul B S

2015-12-01

Mediation is a voluntary process whereby a neutral and impartial third party-t-he mediator--is present to facilitate communication and negotiation between the disputing parties so that amicable settlements can be agreed. Being confidential and non-adversarial in nature, the mediation process and skills are particularly applicable in clinical practice to facilitate challenging communications following adverse events, to assist bioethical decision making and to resolve disputes. Mediation is also a more effective and efficient means of dispute resolution in medical malpractice claims when compared with civil litigation. Health care mediation teams should be set up at individual facilities to provide education and consultation services to frontline staff and patients. At a community level, the Government, the mediation community, and the health care professionals should join forces to promote mediation as a means to settle medical malpractice claims outside of the courtroom.

Coarse-grained molecular simulations of allosteric cooperativity

Energy Technology Data Exchange (ETDEWEB)

Nandigrami, Prithviraj; Portman, John J. [Department of Physics, Kent State University, Kent, Ohio 44242 (United States)

2016-03-14

Interactions between a protein and a ligand are often accompanied by a redistribution of the population of thermally accessible conformations. This dynamic response of the protein’s functional energy landscape enables a protein to modulate binding affinities and control binding sensitivity to ligand concentration. In this paper, we investigate the structural origins of binding affinity and allosteric cooperativity of binding two Ca{sup 2+} ions to each domain of Calmodulin (CaM) through simulations of a simple coarse-grained model. In this model, the protein’s conformational transitions between open and closed conformational ensembles are simulated explicitly and ligand binding and unbinding are treated implicitly within the grand canonical ensemble. Ligand binding is cooperative because the binding sites are coupled through a shift in the dominant conformational ensemble upon binding. The classic Monod-Wyman-Changeux model of allostery with appropriate binding free energies to the open and closed ensembles accurately describes the simulated binding thermodynamics. The simulations predict that the two domains of CaM have distinct binding affinity and cooperativity. In particular, the C-terminal domain binds Ca{sup 2+} with higher affinity and greater cooperativity than the N-terminal domain. From a structural point of view, the affinity of an individual binding loop depends sensitively on the loop’s structural compatibility with the ligand in the bound ensemble, as well as the conformational flexibility of the binding site in the unbound ensemble.

Archiving, ordering and searching: search engines, algorithms, databases and deep mediatization

DEFF Research Database (Denmark)

Andersen, Jack

2018-01-01

This article argues that search engines, algorithms, and databases can be considered as a way of understanding deep mediatization (Couldry & Hepp, 2016). They are embedded in a variety of social and cultural practices and as such they change our communicative actions to be shaped by their logic o...... reviewed recent trends in mediatization research, the argument is discussed and unfolded in-between the material and social constructivist-phenomenological interpretations of mediatization. In conclusion, it is discussed how deep this form of mediatization can be taken to be.......This article argues that search engines, algorithms, and databases can be considered as a way of understanding deep mediatization (Couldry & Hepp, 2016). They are embedded in a variety of social and cultural practices and as such they change our communicative actions to be shaped by their logic...

Review: Oliver Märker & Matthias Trénel (Eds.) (2003). Online-Mediation. Neue Medien in der Konfliktvermittlung – mit Beispielen aus Politik und Wirtschaft [Online-Mediation. New Media in Conflict Resolution—with Examples from Politics and Industry

OpenAIRE

Nicola Döring

2004-01-01

Online-Mediation deals with conflict resolution methods that are carried out partially or completely online. The book analyses online mediation as a socio-technical system through the means of the computer-based technological platform deeply interwoven with conflict-related social communication. The first part of the book discusses the multiple options and restrictions of online communication in moderation and mediation processes. For example, one advantage of online mediation is that geograp...

Evidence for a Common Mechanism of SIRT1 Regulation by Allosteric Activators

Science.gov (United States)

Hubbard, Basil P.; Gomes, Ana P.; Dai, Han; Li, Jun; Case, April W.; Considine, Thomas; Riera, Thomas V.; Lee, Jessica E.; Sook Yen, E; Lamming, Dudley W.; Pentelute, Bradley L.; Schuman, Eli R.; Stevens, Linda A.; Ling, Alvin J. Y.; Armour, Sean M.; Michan, Shaday; Zhao, Huizhen; Jiang, Yong; Sweitzer, Sharon M.; Blum, Charles A.; Disch, Jeremy S.; Ng, Pui Yee; Howitz, Konrad T.; Rolo, Anabela P.; Hamuro, Yoshitomo; Moss, Joel; Perni, Robert B.; Ellis, James L.; Vlasuk, George P.; Sinclair, David A.

2013-01-01

A molecule that treats multiple age-related diseases would have a major impact on global health and economics. The SIRT1 deacetylase has drawn attention in this regard as a target for drug design. Yet controversy exists around the mechanism of sirtuin-activating compounds (STACs). We found that specific hydrophobic motifs found in SIRT1 substrates such as PGC-1α and FOXO3a facilitate SIRT1 activation by STACs. A single amino acid in SIRT1, Glu230, located in a structured N-terminal domain, was critical for activation by all previously reported STAC scaffolds and a new class of chemically distinct activators. In primary cells reconstituted with activation-defective SIRT1, the metabolic effects of STACs were blocked. Thus, SIRT1 can be directly activated through an allosteric mechanism common to chemically diverse STACs. PMID:23471411

Evidence for a common mechanism of SIRT1 regulation by allosteric activators.

Science.gov (United States)

Hubbard, Basil P; Gomes, Ana P; Dai, Han; Li, Jun; Case, April W; Considine, Thomas; Riera, Thomas V; Lee, Jessica E; E, Sook Yen; Lamming, Dudley W; Pentelute, Bradley L; Schuman, Eli R; Stevens, Linda A; Ling, Alvin J Y; Armour, Sean M; Michan, Shaday; Zhao, Huizhen; Jiang, Yong; Sweitzer, Sharon M; Blum, Charles A; Disch, Jeremy S; Ng, Pui Yee; Howitz, Konrad T; Rolo, Anabela P; Hamuro, Yoshitomo; Moss, Joel; Perni, Robert B; Ellis, James L; Vlasuk, George P; Sinclair, David A

2013-03-08

A molecule that treats multiple age-related diseases would have a major impact on global health and economics. The SIRT1 deacetylase has drawn attention in this regard as a target for drug design. Yet controversy exists around the mechanism of sirtuin-activating compounds (STACs). We found that specific hydrophobic motifs found in SIRT1 substrates such as PGC-1α and FOXO3a facilitate SIRT1 activation by STACs. A single amino acid in SIRT1, Glu(230), located in a structured N-terminal domain, was critical for activation by all previously reported STAC scaffolds and a new class of chemically distinct activators. In primary cells reconstituted with activation-defective SIRT1, the metabolic effects of STACs were blocked. Thus, SIRT1 can be directly activated through an allosteric mechanism common to chemically diverse STACs.

A novel antidiabetic drug, fasiglifam/TAK-875, acts as an ago-allosteric modulator of FFAR1.

Directory of Open Access Journals (Sweden)

Chiori Yabuki

Full Text Available Selective free fatty acid receptor 1 (FFAR1/GPR40 agonist fasiglifam (TAK-875, an antidiabetic drug under phase 3 development, potentiates insulin secretion in a glucose-dependent manner by activating FFAR1 expressed in pancreatic β cells. Although fasiglifam significantly improved glycemic control in type 2 diabetes patients with a minimum risk of hypoglycemia in a phase 2 study, the precise mechanisms of its potent pharmacological effects are not fully understood. Here we demonstrate that fasiglifam acts as an ago-allosteric modulator with a partial agonistic activity for FFAR1. In both Ca(2+ influx and insulin secretion assays using cell lines and mouse islets, fasiglifam showed positive cooperativity with the FFAR1 ligand γ-linolenic acid (γ-LA. Augmentation of glucose-induced insulin secretion by fasiglifam, γ-LA, or their combination was completely abolished in pancreatic islets of FFAR1-knockout mice. In diabetic rats, the insulinotropic effect of fasiglifam was suppressed by pharmacological reduction of plasma free fatty acid (FFA levels using a lipolysis inhibitor, suggesting that fasiglifam potentiates insulin release in conjunction with plasma FFAs in vivo. Point mutations of FFAR1 differentially affected Ca(2+ influx activities of fasiglifam and γ-LA, further indicating that these agonists may bind to distinct binding sites. Our results strongly suggest that fasiglifam is an ago-allosteric modulator of FFAR1 that exerts its effects by acting cooperatively with endogenous plasma FFAs in human patients as well as diabetic animals. These findings contribute to our understanding of fasiglifam as an attractive antidiabetic drug with a novel mechanism of action.

Volume transmission and receptor-receptor interactions in heteroreceptor complexes: understanding the role of new concepts for brain communication

Directory of Open Access Journals (Sweden)

Kjell Fuxe

2016-01-01

Full Text Available The discovery of the central monoamine neurons not only demonstrated novel types of brain stem neurons forming global terminal networks all over the brain and the spinal cord, but also to a novel type of communication called volume transmission. It is a major mode of communication in the central nervous system that takes places in the extracellular fluid and the cerebral spinal fluid through diffusion and flow of molecules, like neurotransmitters and extracellular vesicles. The integration of synaptic and volume transmission takes place through allosteric receptor-receptor interactions in heteroreceptor complexes. These heterocomplexes represent major integrator centres in the plasma membrane and their protomers act as moonlighting proteins undergoing dynamic changes and their structure and function. In fact, we propose that the molecular bases of learning and memory can be based on the reorganization of multiples homo and heteroreceptor complexes into novel assembles in the post-junctional membranes of synapses.

Mediation – Mandatory Information and Facultative Applicability

Directory of Open Access Journals (Sweden)

Monica Pocora

2015-12-01

Full Text Available Considering that mediation is a facilitating way to access the alternative solving of litigations in conciliatory terms, the study is encouraging using the mediation and providing a balanced relationship between mediation and judiciary procedures. As an aftermath of summary definition, we can say that role of mediation is to overcome the communicative barriers in order to solve the conflict and save the fact situation on both parts. The study aims at analyzing objectively all consequences of both solving ways of litigations: traditional one, through the law court and mediation, with the advantages derived from them (celerity vs. time consuming, expensive judiciary proceedings vs. low costs, etc.

Fluorescence Polarization Screening Assays for Small Molecule Allosteric Modulators of ABL Kinase Function.

Science.gov (United States)

Grover, Prerna; Shi, Haibin; Baumgartner, Matthew; Camacho, Carlos J; Smithgall, Thomas E

2015-01-01

The ABL protein-tyrosine kinase regulates intracellular signaling pathways controlling diverse cellular processes and contributes to several forms of cancer. The kinase activity of ABL is repressed by intramolecular interactions involving its regulatory Ncap, SH3 and SH2 domains. Small molecules that allosterically regulate ABL kinase activity through its non-catalytic domains may represent selective probes of ABL function. Here we report a screening assay for chemical modulators of ABL kinase activity that target the regulatory interaction of the SH3 domain with the SH2-kinase linker. This fluorescence polarization (FP) assay is based on a purified recombinant ABL protein consisting of the N-cap, SH3 and SH2 domains plus the SH2-kinase linker (N32L protein) and a short fluorescein-labeled probe peptide that binds to the SH3 domain. In assay development experiments, we found that the probe peptide binds to the recombinant ABL N32L protein in vitro, producing a robust FP signal that can be competed with an excess of unlabeled peptide. The FP signal is not observed with control N32L proteins bearing either an inactivating mutation in the SH3 domain or enhanced SH3:linker interaction. A pilot screen of 1200 FDA-approved drugs identified four compounds that specifically reduced the FP signal by at least three standard deviations from the untreated controls. Secondary assays showed that one of these hit compounds, the antithrombotic drug dipyridamole, enhances ABL kinase activity in vitro to a greater extent than the previously described ABL agonist, DPH. Docking studies predicted that this compound binds to a pocket formed at the interface of the SH3 domain and the linker, suggesting that it activates ABL by disrupting this regulatory interaction. These results show that screening assays based on the non-catalytic domains of ABL can identify allosteric small molecule regulators of kinase function, providing a new approach to selective drug discovery for this important