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Sample records for non-selective p2 antagonist

  1. Critical Evaluation of P2X7 Receptor Antagonists in Selected Seizure Models

    Science.gov (United States)

    Fischer, Wolfgang; Franke, Heike; Krügel, Ute; Müller, Heiko; Dinkel, Klaus; Lord, Brian; Letavic, Michael A.; Henshall, David C.; Engel, Tobias

    2016-01-01

    The ATP-gated P2X7 receptor (P2X7R) is a non-selective cation channel which senses high extracellular ATP concentrations and has been suggested as a target for the treatment of neuroinflammation and neurodegenerative diseases. The use of P2X7R antagonists may therefore be a viable approach for treating CNS pathologies, including epileptic disorders. Recent studies showed anticonvulsant potential of P2X7R antagonists in certain animal models. To extend this work, we tested three CNS-permeable P2X7R blocker (Brilliant Blue G, AFC-5128, JNJ-47965567) and a natural compound derivative (tanshinone IIA sulfonate) in four well-characterized animal seizure models. In the maximal electroshock seizure threshold test and the pentylenetetrazol (PTZ) seizure threshold test in mice, none of the four compounds demonstrated anticonvulsant effects when given alone. Notably, in combination with carbamazepine, both AFC-5128 and JNJ-47965567 increased the threshold in the maximal electroshock seizure test. In the PTZ-kindling model in rats, useful for testing antiepileptogenic activities, Brilliant Blue G and tanshinone exhibited a moderate retarding effect, whereas the potent P2X7R blocker AFC-5128 and JNJ-47965567 showed a significant and long-lasting delay in kindling development. In fully kindled rats, the investigated compounds revealed modest effects to reduce the mean seizure stage. Furthermore, AFC-5128- and JNJ-47965567-treated animals displayed strongly reduced Iba 1 and GFAP immunoreactivity in the hippocampal CA3 region. In summary, our results show that P2X7R antagonists possess no remarkable anticonvulsant effects in the used acute screening tests, but can attenuate chemically-induced kindling. Further studies would be of interest to support the concept that P2X7R signalling plays a crucial role in the pathogenesis of epileptic disorders. PMID:27281030

  2. X-ray structures define human P2X3 receptor gating cycle and antagonist action

    Science.gov (United States)

    Mansoor, Steven E.; Lü, Wei; Oosterheert, Wout; Shekhar, Mrinal; Tajkhorshid, Emad; Gouaux, Eric

    2016-10-01

    P2X receptors are trimeric, non-selective cation channels activated by ATP that have important roles in the cardiovascular, neuronal and immune systems. Despite their central function in human physiology and although they are potential targets of therapeutic agents, there are no structures of human P2X receptors. The mechanisms of receptor desensitization and ion permeation, principles of antagonism, and complete structures of the pore-forming transmembrane domains of these receptors remain unclear. Here we report X-ray crystal structures of the human P2X3 receptor in apo/resting, agonist-bound/open-pore, agonist-bound/closed-pore/desensitized and antagonist-bound/closed states. The open state structure harbours an intracellular motif we term the ‘cytoplasmic cap’, which stabilizes the open state of the ion channel pore and creates lateral, phospholipid-lined cytoplasmic fenestrations for water and ion egress. The competitive antagonists TNP-ATP and A-317491 stabilize the apo/resting state and reveal the interactions responsible for competitive inhibition. These structures illuminate the conformational rearrangements that underlie P2X receptor gating and provide a foundation for the development of new pharmacological agents.

  3. Blockade of murine T cell activation by antagonists of P2Y6 and P2X7 receptors.

    Science.gov (United States)

    Tsukimoto, Mitsutoshi; Tokunaga, Akihiro; Harada, Hitoshi; Kojima, Shuji

    2009-07-10

    Extracellular nucleotides and their metabolites activate ionotropic P2X and metabotropic P2Y receptors on the surface of various types of cells. Here, we investigated the involvement of P2X and P2Y receptor-mediated signaling in TCR-dependent T cell activation. Murine T cells were activated by stimulation of TCR, and both CD25 expression and interleukin (IL)-2 production were observed in activated T cells. Ecto-nucleotidase apyrase and P2Y6 antagonist MRS2578 significantly blocked the increases of both CD25 expression and IL-2 production, and P2X7 antagonists A438079 and oxidized ATP inhibited IL-2 production rather than CD25 expression, suggesting the involvement of P2Y6 and P2X7 receptors in different processes of T cell activation. MRS2578 also blocked TCR-dependent elevation of cytosolic Ca2+ in T cells. The P2X7 and P2Y6 receptors were expressed in murine CD4 T cells. In conclusion, our results indicate that activation of P2Y6 and P2X7 receptors contributes to T cell activation via TCR.

  4. Development of selective agonists and antagonists of P2Y receptors

    OpenAIRE

    2008-01-01

    Although elucidation of the medicinal chemistry of agonists and antagonists of the P2Y receptors has lagged behind that of many other members of group A G protein-coupled receptors, detailed qualitative and quantitative structure–activity relationships (SARs) were recently constructed for several of the subtypes. Agonists selective for P2Y1, P2Y2, and P2Y6 receptors and nucleotide antagonists selective for P2Y1 and P2Y12 receptors are now known. Selective nonnucleotide antagonists were report...

  5. X-ray structures define human P2X3 receptor gating cycle and antagonist action

    NARCIS (Netherlands)

    Mansoor, Steven E.; Lü, Wei; Oosterheert, W.; Shekhar, Mrinal; Tajkhorshid, Emad; Gouaux, Eric

    2016-01-01

    P2X receptors are trimeric, non-selective cation channels activated by ATP that have important roles in the cardiovascular, neuronal and immune systems. Despite their central function in human physiology and although they are potential targets of therapeutic agents, there are no structures of human

  6. Pyrrolo- and pyridomorphinans: non-selective opioid antagonists and delta opioid agonists/mu opioid partial agonists.

    Science.gov (United States)

    Kumar, V; Clark, M J; Traynor, J R; Lewis, J W; Husbands, S M

    2014-08-01

    Opioid ligands have found use in a number of therapeutic areas, including for the treatment of pain and opiate addiction (using agonists) and alcohol addiction (using antagonists such as naltrexone and nalmefene). The reaction of imines, derived from the opioid ligands oxymorphone and naltrexone, with Michael acceptors leads to pyridomorphinans with structures similar to known pyrrolo- and indolomorphinans. One of the synthesized compounds, 5e, derived from oxymorphone had substantial agonist activity at delta opioid receptors but not at mu and/or kappa opioid receptors and in that sense profiled as a selective delta opioid receptor agonist. The pyridomorphinans derived from naltrexone and naloxone were all found to be non-selective potent antagonists and as such could have utility as treatments for alcohol abuse.

  7. The incentive amplifying effects of nicotine are reduced by selective and non-selective dopamine antagonists in rats.

    Science.gov (United States)

    Palmatier, Matthew I; Kellicut, Marissa R; Brianna Sheppard, A; Brown, Russell W; Robinson, Donita L

    2014-11-01

    Nicotine is a psychomotor stimulant with 'reinforcement enhancing' effects--the actions of nicotine in the brain increase responding for non-nicotine rewards. We hypothesized that this latter effect of nicotine depends on increased incentive properties of anticipatory cues; consistent with this hypothesis, multiple laboratories have reported that nicotine increases sign tracking, i.e. approach to a conditioned stimulus (CS), in Pavlovian conditioned-approach tasks. Incentive motivation and sign tracking are mediated by mesolimbic dopamine (DA) transmission and nicotine facilitates mesolimbic DA release. Therefore, we hypothesized that the incentive-promoting effects of nicotine would be impaired by DA antagonists. To test this hypothesis, separate groups of rats were injected with nicotine (0.4mg/kg base) or saline prior to Pavlovian conditioning sessions in which a CS (30s illumination of a light or presentation of a lever) was immediately followed by a sweet reward delivered in an adjacent location. Both saline and nicotine pretreated rats exhibited similar levels of conditioned approach to the reward location (goal tracking), but nicotine pretreatment significantly increased approach to the CS (sign tracking), regardless of type (lever or light). The DAD1 antagonist SCH-23390 and the DAD2/3 antagonist eticlopride reduced conditioned approach in all rats, but specifically reduced goal tracking in the saline pretreated rats and sign tracking in the nicotine pretreated rats. The non-selective DA antagonist flupenthixol reduced sign-tracking in nicotine rats at all doses tested; however, only the highest dose of flupenthixol reduced goal tracking in both nicotine and saline groups. The reductions in conditioned approach behavior, especially those by SCH-23390, were dissociated from simple motor suppressant effects of the antagonists. These experiments are the first to investigate the effects of dopaminergic drugs on the facilitation of sign-tracking engendered by

  8. Radiosensitizing Effect of P2X7 Receptor Antagonist on Melanoma in vitro and in vivo.

    Science.gov (United States)

    Tanamachi, Keisuke; Nishino, Keisuke; Mori, Natsuki; Suzuki, Toshihiro; Tanuma, Sei-Ichi; Abe, Ryo; Tsukimoto, Mitsutoshi

    2017-03-24

    Melanoma is highly malignant, and generally exhibits radioresistance, responding poorly to radiation therapy. We previously reported that activation of P2X7, P2Y6, and P2Y12 receptors is involved in the DNA damage response after γ-irradiation of human lung adenocarcinoma A549 cells. However, it is not clear whether these receptors are also involved in the case of melanoma cells, although P2X7 receptor is highly expressed in various cancers, including melanoma. Here, we show that P2X7 receptor antagonist enhances radiation-induced cytotoxicity in B16 melanoma cells in vitro and in vivo. We confirmed that these cells express P2X7 receptor mRNA and exhibit P2X7 receptor-mediated activities, such as ATP-induced pore formation and cytotoxicity. We further examined the radiosensitizing effect of P2X7 receptor antagonist Brilliant Blue G (BBG) in vitro by colony formation assay of B16 cells. γ-Irradiation dose-dependently reduced cell survival, and pretreatment with BBG enhanced the radiation-induced cytotoxicity. BBG pretreatment also decreased the number of DNA repair foci in nuclei, supporting involvement of P2X7 receptor in the DNA damage response. Finally, we investigated the radiosensitizing effect of BBG on B16 melanoma cells inoculated into the hind footpad of C57BL/6 mice. Neither 1 Gy γ-irradiation alone nor BBG alone suppressed the increase of tumor volume, but the combination of irradiation and BBG significantly suppressed tumor growth. Our results suggest that P2X7 receptor antagonist BBG has a radiosensitizing effect in melanoma in vitro and in vivo. BBG, which is used as a food coloring agent, appears to be a promising candidate as a radiosensitizer.

  9. Identification and characterization of a selective allosteric antagonist of human P2X4 receptor channels.

    Science.gov (United States)

    Ase, Ariel R; Honson, Nicolette S; Zaghdane, Helmi; Pfeifer, Tom A; Séguéla, Philippe

    2015-04-01

    P2X4 is an ATP-gated nonselective cation channel highly permeable to calcium. There is increasing evidence that this homomeric purinoceptor, which is expressed in several neuronal and immune cell types, is involved in chronic pain and inflammation. The current paucity of unambiguous pharmacological tools available to interrogate or modulate P2X4 function led us to pursue the search for selective antagonists. In the high-throughput screen of a compound library, we identified the phenylurea BX430 (1-(2,6-dibromo-4-isopropyl-phenyl)-3-(3-pyridyl)urea, molecular weight = 413), with antagonist properties on human P2X4-mediated calcium uptake. Patch-clamp electrophysiology confirmed direct inhibition of P2X4 currents by extracellular BX430, with submicromolar potency (IC50 = 0.54 µM). BX430 is highly selective, having virtually no functional impact on all other P2X subtypes, namely, P2X1-P2X3, P2X5, and P2X7, at 10-100 times its IC50. Unexpected species differences were noticed, as BX430 is a potent antagonist of zebrafish P2X4 but has no effect on rat and mouse P2X4 orthologs. The concentration-response curve for ATP on human P2X4 in the presence of BX430 shows an insurmountable blockade, indicating a noncompetitive allosteric mechanism of action. Using a fluorescent dye uptake assay, we observed that BX430 also effectively suppresses ATP-evoked and ivermectin-potentiated membrane permeabilization induced by P2X4 pore dilation. Finally, in single-cell calcium imaging, we validated its selective inhibitory effects on native P2X4 channels at the surface of human THP-1 cells that were differentiated into macrophages. In summary, this ligand provides a novel molecular probe to assess the specific role of P2X4 in inflammatory and neuropathic conditions, where ATP signaling has been shown to be dysfunctional.

  10. Docking-based virtual screening of potential human P2Y12 receptor antagonists

    Institute of Scientific and Technical Information of China (English)

    Hua Chen; Xianchi Dong; Minyun Zhou; Haiming Shi; Xinping Luo

    2011-01-01

    Platelet plays essential roles in hemostasis and its dysregulation can lead to arterial thrombosis. P2Y12 is an important platelet membrane adenosine diphosphate receptor,and its antagonists have been widely developed as anticoagulation agents. The current P2Y12 inhibitors available in clinical practice have not fully achieved saOsfactory antithrombotic effects, leaving room for further improvement To identify new chemical compounds as potential anticoagulation inhibitors, we constructed a three-dimensional structure model of human P2Y12 by homology modeling based on the recently reported G-protein coupled receptor Meleagris gallopavo βl adrenergic receptor. Virtual screening of the modeled P2Y12 against three subsets of small molecules from the ZINC database, namely lead-like, fragment-like, and drug-like, identified a number of compounds tbat might have high binding affinity to P2Y12.Detailed analyses of the top three compounds from each subset with the highest scores indicated that all of these compounds beard a hydrophobic bulk supplemented with a few polar atoms which bound at the ligand binding site via largely hydrophobic interactions with the receptor. This study not only provides a structure model of P2Y12 for rational design of anti-platelet inhibitors, but also identifies some potential chemicals for further development.

  11. Discovery of Potential Orthosteric and Allosteric Antagonists of P2Y1R from Chinese Herbs by Molecular Simulation Methods

    Directory of Open Access Journals (Sweden)

    Xu Zhang

    2016-01-01

    Full Text Available P2Y1 receptor (P2Y1R, which belongs to G protein-coupled receptors (GPCRs, is an important target in ADP-induced platelet aggregation. The crystal structure of P2Y1R has been solved recently, which revealed orthosteric and allosteric ligand-binding sites with the details of ligand-protein binding modes. And it suggests that P2Y1R antagonists, which recognize two distinct sites, could potentially provide an efficacious and safe antithrombotic profile. In present paper, 2D similarity search, pharmacophore based screening, and molecular docking were used to explore the potential natural P2Y1R antagonists. 2D similarity search was used to classify orthosteric and allosteric antagonists of P2Y1R. Based on the result, pharmacophore models were constructed and validated by the test set. Optimal models were selected to discover potential P2Y1R antagonists of orthosteric and allosteric sites from Traditional Chinese Medicine (TCM. And the hits were filtered by Lipinski’s rule. Then molecular docking was used to refine the results of pharmacophore based screening and analyze the binding mode of the hits and P2Y1R. Finally, two orthosteric and one allosteric potential compounds were obtained, which might be used in future P2Y1R antagonists design. This work provides a reliable guide for discovering natural P2Y1R antagonists acting on two distinct sites from TCM.

  12. Discovery of Potential Orthosteric and Allosteric Antagonists of P2Y1R from Chinese Herbs by Molecular Simulation Methods

    Science.gov (United States)

    Lu, Fang; Jiang, Lu-di; Qiao, Lian-sheng; Xiang, Yu-hong

    2016-01-01

    P2Y1 receptor (P2Y1R), which belongs to G protein-coupled receptors (GPCRs), is an important target in ADP-induced platelet aggregation. The crystal structure of P2Y1R has been solved recently, which revealed orthosteric and allosteric ligand-binding sites with the details of ligand-protein binding modes. And it suggests that P2Y1R antagonists, which recognize two distinct sites, could potentially provide an efficacious and safe antithrombotic profile. In present paper, 2D similarity search, pharmacophore based screening, and molecular docking were used to explore the potential natural P2Y1R antagonists. 2D similarity search was used to classify orthosteric and allosteric antagonists of P2Y1R. Based on the result, pharmacophore models were constructed and validated by the test set. Optimal models were selected to discover potential P2Y1R antagonists of orthosteric and allosteric sites from Traditional Chinese Medicine (TCM). And the hits were filtered by Lipinski's rule. Then molecular docking was used to refine the results of pharmacophore based screening and analyze the binding mode of the hits and P2Y1R. Finally, two orthosteric and one allosteric potential compounds were obtained, which might be used in future P2Y1R antagonists design. This work provides a reliable guide for discovering natural P2Y1R antagonists acting on two distinct sites from TCM. PMID:27635149

  13. In pursuit of P2X3 antagonists: novel therapeutics for chronic pain and afferent sensitization.

    Science.gov (United States)

    Ford, Anthony P

    2012-02-01

    Treating pain by inhibiting ATP activation of P2X3-containing receptors heralds an exciting new approach to pain management, and Afferent's program marks the vanguard in a new class of drugs poised to explore this approach to meet the significant unmet needs in pain management. P2X3 receptor subunits are expressed predominately and selectively in so-called C- and Aδ-fiber primary afferent neurons in most tissues and organ systems, including skin, joints, and hollow organs, suggesting a high degree of specificity to the pain sensing system in the human body. P2X3 antagonists block the activation of these fibers by ATP and stand to offer an alternative approach to the management of pain and discomfort. In addition, P2X3 is expressed pre-synaptically at central terminals of C-fiber afferent neurons, where ATP further sensitizes transmission of painful signals. As a result of the selectivity of the expression of P2X3, there is a lower likelihood of adverse effects in the brain, gastrointestinal, or cardiovascular tissues, effects which remain limiting factors for many existing pain therapeutics. In the periphery, ATP (the factor that triggers P2X3 receptor activation) can be released from various cells as a result of tissue inflammation, injury or stress, as well as visceral organ distension, and stimulate these local nociceptors. The P2X3 receptor rationale has aroused a formidable level of investigation producing many reports that clarify the potential role of ATP as a pain mediator, in chronic sensitized states in particular, and has piqued the interest of pharmaceutical companies. P2X receptor-mediated afferent activation has been implicated in inflammatory, visceral, and neuropathic pain states, as well as in airways hyperreactivity, migraine, itch, and cancer pain. It is well appreciated that oftentimes new mechanisms translate poorly from models into clinical efficacy and effectiveness; however, the breadth of activity seen from P2X3 inhibition in models offers

  14. P2Y12-ADP receptor antagonists: Days of future and past

    Institute of Scientific and Technical Information of China (English)

    Marc Laine; Franck Paganelli; Laurent Bonello

    2016-01-01

    Antiplatelet therapy is the cornerstone of the therapeutic arsenal in coronary artery disease.Thanks to a better understanding in physiology,pharmacology and pharmacogenomics huge progress were made in the field of platelet reactivity inhibition thus allowing theexpansion of percutaneous coronary intervention.Stent implantation requires the combination of two antiplatelet agents acting in a synergistic way.Asprin inhibit the cyclo-oxygenase pathway of platelet activation while clopidogrel is a P2Y12 adenosine diphosphate(ADP)-receptor antagonist.This dual antiplatelet therapy has dramatically improved the prognosis of stented patients.However,due to pharmacological limitations of clopidogrel(interindividual variability in its biological efficacy,slow onset of action,mild platelet reactivity inhibition)ischemic recurrences remained high following stent implantation especially in acute coronary syndrome patients.Thus,more potent P2Y12-ADP receptor inhibitors were developped including prasugrel,ticagrelor and more recently cangrelor to overcome these pitfalls.These new agents reduced the rate of thrombotic events in acute coronary syndrome patients at the cost of an increased bleeding risk.The abundance in antiplatelet agents allow us to tailor our strategy based on the thrombotic/bleeding profile of each patient.Recently,the ACCOAST trial cast a doubt on the benefit of pre treatment in non-ST segment elevation acute coronary syndrome.The aim of the present review is to summarize the results of the main studies dealing with antiplatelet therapy in stented/acute coronary syndromes patients.

  15. The P2Y(12 antagonists, 2MeSAMP and cangrelor, inhibit platelet activation through P2Y(12/G(i-dependent mechanism.

    Directory of Open Access Journals (Sweden)

    Binggang Xiang

    Full Text Available BACKGROUND: ADP is an important physiological agonist that induces integrin activation and platelet aggregation through its receptors P2Y(1 (Gα(q-coupled and P2Y(12 (Gα(i-coupled. P2Y(12 plays a critical role in platelet activation and thrombosis. Adenosine-based P2Y(12 antagonists, 2-methylthioadenosine 5'-monophosphate triethylammonium salt hydrate (2MeSAMP and Cangrelor (AR-C69931MX have been widely used to demonstrate the role of P2Y(12 in platelet function. Cangrelor is being evaluated in clinical trials of thrombotic diseases. However, a recent study reported that both 2MeSAMP and Cangrelor raise intra-platelet cAMP levels and inhibit platelet aggregation through a P2Y(12-independent mechanism. METHODOLOGY/PRINCIPAL FINDINGS: The present work, using P2Y(12 deficient mice, sought to clarify previous conflicting reports and to elucidate the mechanisms by which 2MeSAMP and Cangrelor inhibit platelet activation and thrombosis. 2MeSAMP and Cangrelor inhibited aggregation and ATP release of wild-type but not P2Y(12 deficient platelets. 2MeSAMP and Cangrelor neither raised intracellular cAMP concentrations nor induced phosphorylation of vasodilator-stimulated phosphoprotein (VASP in washed human or mouse platelets. Furthermore, unlike the activators (PGI(2 and forskolin of the cAMP pathway, 2MeSAMP and Cangrelor failed to inhibit Ca(2+ mobilization, Akt phosphorylation, and Rap1b activation in P2Y(12 deficient platelets. Importantly, while injection of Cangrelor inhibited thrombus formation in a FeCl(3-induced thrombosis model in wild-type mice, it failed to affect thrombus formation in P2Y(12 deficient mice. CONCLUSIONS: These data together demonstrate that 2MeSAMP and Cangrelor inhibit platelet function through the P2Y(12-dependent mechanism both in vitro and in vivo.

  16. Optimization of ketone-based P2Y(12) receptor antagonists as antithrombotic agents: pharmacodynamics and receptor kinetics considerations.

    Science.gov (United States)

    Giordanetto, Fabrizio; Bach, Peter; Zetterberg, Fredrik; Antonsson, Thomas; Bylund, Ruth; Johansson, Johan; Sellén, Mikael; Brown, David; Hideståhl, Lotta; Berntsson, Pia; Hovdal, Daniel; Zachrisson, Helen; Björkman, Jan-Arne; van Giezen, J J J

    2014-07-01

    Modification of a series of P2Y12 receptor antagonists by replacement of the ester functionality was aimed at minimizing the risk of in vivo metabolic instability and pharmacokinetic variability. The resulting ketones were then optimized for their P2Y12 antagonistic and anticoagulation effects in combination with their physicochemical and absorption profiles. The most promising compound showed very potent antiplatelet action in vivo. However, pharmacodynamic-pharmacokinetic analysis did not reveal a significant separation between its anti-platelet and bleeding effects. The relevance of receptor binding kinetics to the in vivo profile is described. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Identification of high-affinity P2Y₁₂ antagonists based on a phenylpyrazole glutamic acid piperazine backbone.

    Science.gov (United States)

    Zech, Gernot; Hessler, Gerhard; Evers, Andreas; Weiss, Tilo; Florian, Peter; Just, Melitta; Czech, Jörg; Czechtizky, Werngard; Görlitzer, Jochen; Ruf, Sven; Kohlmann, Markus; Nazaré, Marc

    2012-10-25

    A series of novel, highly potent P2Y₁₂ antagonists as inhibitors of platelet aggregation based on a phenylpyrazole glutamic acid piperazine backbone is described. Exploration of the structural requirements of the substituents by probing the structure-activity relationship along this backbone led to the discovery of the N-acetyl-(S)-proline cyclobutyl amide moiety as a highly privileged motif. Combining the most favorable substituents led to remarkably potent P2Y₁₂ antagonists displaying not only low nanomolar binding affinity to the P2Y₁₂ receptor but also a low nanomolar inhibition of platelet aggregation in the human platelet rich plasma assay with IC₅₀ values below 50 nM. Using a homology and a three-dimensional quantitative structure-activity relationship model, a binding hypothesis elucidating the impact of several structural features was developed.

  18. Identification of atropine- and P2X1 receptor antagonist-resistant, neurogenic contractions of the urinary bladder.

    Science.gov (United States)

    Kennedy, Charles; Tasker, Paul N; Gallacher, Gemma; Westfall, Timothy D

    2007-01-24

    Acetylcholine and ATP are excitatory cotransmitters in parasympathetic nerves. We used P2X1 receptor antagonists to further characterize the purinergic component of neurotransmission in isolated detrusor muscle of guinea pig urinary bladder. In the presence of atropine (1 microM) and prazosin (100 nM), pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS) (0.1-100 microM) and suramin (1-300 microM) inhibited contractions evoked by 4 Hz nerve stimulation in a concentration-dependent manner (IC50 of 6.9 and 13.4 microM, respectively). Maximum inhibition was 50-60%, which was unaffected by coadministration of the ectonucleotidase inhibitor ARL67156 (6-N,N-diethyl-D-beta,gamma-dibromomethyleneATP) (100 microM). The remaining responses were abolished by tetrodotoxin (1 microM). PPADS and suramin also reduced contractions to exogenous ATP (300 microM) by 40-50%, but abolished those to the P2X1 agonist alpha,beta-methyleneATP (alpha,beta-meATP) (1 microM). The P2X1 antagonists reactive blue 2, NF279 (8,8'-[carbonylbis(imino-4,1-phenylenecarbonylimino-4,1-phenylenecarbonylimino)] bis-1,3,5-naphthalenetrisulfonic acid), MRS2159 (pyridoxal-alpha5-phosphate-6-phenylazo-4'-carboxylic acid) (100 microM), and NF449 [4,4',4,4-(carbonylbis(imino-5,1,3-benzenetriylbis(carbonylimino)))tetrakis-benzene-1,3-disulfonic acid] (3 microM) abolished contractions to alpha,beta-meATP (1 microM; n = 4-5), but only reduced contractions evoked by 4 Hz nerve stimulation by approximately 40-60% (n = 4-6) and ATP by 30-60% (n = 4-7). However, prolonged exposure to alpha,beta-meATP (50 microM) abolished contractions evoked by all three stimuli (n = 5-12). PPADS (100 microM) and suramin (300 microM) reduced the peak neurogenic contraction of the mouse urinary bladder to 30-40% of control. At the same concentrations, the P2X1 antagonists abolished the nonadrenergic, purinergic component of neurogenic contractions in the guinea pig vas deferens (n = 4-5). Thus, P2X1 receptor antagonists inhibit

  19. Selective P2X7 receptor antagonists for chronic inflammation and pain

    OpenAIRE

    Carroll, William A; Donnelly-Roberts, Diana; Jarvis, Michael F.

    2008-01-01

    ATP, acting on P2X7 receptors, stimulates changes in intracellular calcium concentrations, maturation, and release of interleukin-1β (IL-1β), and following prolonged agonist exposure, cell death. The functional effects of P2X7 receptor activation facilitate several proinflammatory processes associated with arthritis. Within the nervous system, these proinflammatory processes may also contribute to the development and maintenance of chronic pain. Emerging data from genetic knockout studies hav...

  20. Chronic administration of the selective P2X3, P2X2/3 receptor antagonist, A-317491, transiently attenuates cancer-induced bone pain in mice

    DEFF Research Database (Denmark)

    Hansen, Rikke Rie; Nasser, Arafat; Falk, Sarah;

    2012-01-01

    The purinergic P2X3 and P2X2/3 receptors are in the peripheral nervous system almost exclusively confined to afferent sensory neurons, where they are found both at peripheral and central synapses. The P2X3 receptor is implicated in both neuropathic and inflammatory pain. However, the role of the ...

  1. Discovery of P2X7 receptor-selective antagonists offers new insights into P2X7 receptor function and indicates a role in chronic pain states

    OpenAIRE

    Donnelly-Roberts, D L; Jarvis, M F

    2007-01-01

    ATP-sensitive P2X7 receptors are localized on cells of immunological origin including peripheral macrophages and glial cells in the CNS. Activation of P2X7 receptors leads to rapid changes in intracellular calcium concentrations, release of the proinflammatory cytokine interleukin-1β and following prolonged agonist exposure, the formation of cytolytic pores in plasma membranes. Both the localization and functional consequences of P2X7 receptor activation indicate a role in inflammatory proces...

  2. Clopidogrel (Plavix®), a P2Y(12) receptor antagonist, inhibits bone cell function in vitro and decreases trabecular bone in vivo

    DEFF Research Database (Denmark)

    Syberg, Susanne; Brandao-Burch, Andrea; Patel, Jessal J

    2012-01-01

    Clopidogrel (Plavix®), a selective P2Y(12) receptor antagonist, is widely prescribed to reduce the risk of heart attack and stroke and acts via the inhibition of platelet aggregation. Accumulating evidence now suggests that extracellular nucleotides, signalling through P2 receptors, play...

  3. Involvement of the P2X7 purinergic receptor in inflammation: an update of antagonists series since 2009 and their promising therapeutic potential.

    Science.gov (United States)

    Baudelet, Davy; Lipka, Emmanuelle; Millet, Régis; Ghinet, Alina

    2015-01-01

    The purinergic receptor P2X7 is highly expressed in immune peripheral and central cells suggesting its important role in numerous diseases characterized by inflammatory processes like cancer, or neurodegenerative pathologies in relation with modulation of the immune system. Thereby, antagonization of this receptor may be a hopeful therapeutic strategy to treat a large range of diseases. Indeed, selective P2X7 antagonists display beneficial anti-inflammatory, analgesic, and in some cases, anticancer properties. This article will review the involvement of P2X7 in the immune system, the update of P2X7 antagonists series since 2009 and their promising therapeutic potential for the treatment of several immune- related diseases.

  4. CXCR4特异性拮抗剂SDF-1P2G54的构建及活性评价%Construction of SDF-1P2G54, a specific antagonist of CXCR4

    Institute of Scientific and Technical Information of China (English)

    杨飞华; 龙北国; 谭毅; 龚雅; 马伟峰

    2012-01-01

    目的 对SDF-1进行遗传改造,将其第2位氨基酸由脯氨酸(P)突变为甘氨酸(G),且缺失其C-端α螺旋结构,以获得一种CXCR4特异性拮抗剂SDF- 1P2G54.方法 将PCR扩增的SDF-1突变体SDF-1p2g54的基因插入表达载体pET-30a(+),并转化BL21(DE3)菌株.IPTG诱导表达的重组蛋白SDF-1P2G54在变性条件下采用镍柱亲和层析纯化,并通过梯度稀释和超滤方法得以复性.利用趋化实验鉴定SDF-1P2G54对Jurkat细胞的趋化活性及对SDF-1趋化活性的抑制效应,流式细胞仪检测SDF-1P2G54诱导MOLT4细胞钙内流及细胞表面CXCR4内在化的能力.结果 SDF-1P2G54完全丧失激活CXCR4、趋化Jurkat细胞跨膜迁移和诱导MOLT4细胞钙内流的能力,却保持了与CXCR4的高亲和性,能有效抑制野生型SDF-1对Jurkat的趋化效应、诱导MOLT4细胞表面CXCR4的快速内在化.结论 SDF-1P2G54是一种新型的CXCR4特异性拮抗剂,具有开发成抑制HIV-1感染和癌细胞转移等重大疾病特效药物的潜在应用价值.%Objective To obtain a specific antagonist of CXCR4, SDF-1P2G54 by mutating SDF-1 second proline (P) into glycin (G) and removing the a-helix of its C-terminal. Methods SDF-lp2g54 gene amplified by PCR was inserted into the vector pET-30a (+) and transformed into Escherichia coli (E. Coli) strain BL21. After IPTG induction of E. Coli, the expressed recombinant protein was purified with nickel-affinity chromatography column under denaturing conditions and refolded with gradient dilution and ultra-filtration. The chemotactic effect of SDF-1P2G54 on Jurkat cells and its antagonistic effect against SDF-1 were determined by transwell assay; flow cytometry was used to assay the ability of SDF-1 P2G54 to induce calcium influx and CXCR4 internalization in MOLT4 cells. Results The recombinant protein SDF-1P2G54 completely lost the functions to activate CXCR4 or to induce transmembrane migration of Jurkat cells and calcium influx in MOLT4 cells, but maintained a

  5. Selective and rapid monitoring of dual platelet inhibition by aspirin and P2Y12 antagonists by using multiple electrode aggregometry

    Directory of Open Access Journals (Sweden)

    Lorenz Reinhard

    2010-05-01

    Full Text Available Abstract Background Poor platelet inhibition by aspirin or clopidogrel has been associated with adverse outcomes in patients with cardiovascular diseases. A reliable and facile assay to measure platelet inhibition after treatment with aspirin and a P2Y12 antagonist is lacking. Multiple electrode aggregometry (MEA, which is being increasingly used in clinical studies, is sensitive to platelet inhibition by aspirin and clopidogrel, but a critical evaluation of MEA monitoring of dual anti-platelet therapy with aspirin and P2Y12 antagonists is missing. Design and Methods By performing in vitro and ex vivo experiments, we evaluated in healthy subjects the feasibility of using MEA to monitor platelet inhibition of P2Y12 antagonists (clopidogrel in vivo, cangrelor in vitro and aspirin (100 mg per day in vivo, and 1 mM or 5.4 mM in vitro alone, and in combination. Statistical analyses were performed by the Mann-Whitney rank sum test, student' t-test, analysis of variance followed by the Holm-Sidak test, where appropriate. Results ADP-induced platelet aggregation in hirudin-anticoagulated blood was inhibited by 99.3 ± 1.4% by in vitro addition of cangrelor (100 nM; p 95% and 100 ± 3.2%, respectively (p in vitro or ex vivo. Oral intake of clopidogrel did not significantly reduce AA-induced aggregation, but P2Y12 blockade by cangrelor (100 nM in vitro diminished AA-stimulated aggregation by 53 ± 26% (p Conclusions Selective platelet inhibition by aspirin and P2Y12 antagonists alone and in combination can be rapidly measured by MEA. We suggest that dual anti-platelet therapy with these two types of anti-platelet drugs can be optimized individually by measuring platelet responsiveness to ADP and AA with MEA before and after drug intake.

  6. Platelet reactivity after administration of third generation P2Y12-antagonists does not depend on body weight in contrast to clopidogrel.

    Science.gov (United States)

    Olivier, Christoph B; Schnabel, Katharina; Weber, Susanne; Zhou, Qian; Bode, Christoph; Moser, Martin; Diehl, Philipp

    2016-07-01

    The current standard of antiplatelet therapy for patients with myocardial infarction (MI) includes the P2Y12-receptor antagonist clopidogrel, prasugrel or ticagrelor. While it has been shown that platelet reactivity after clopidogrel administration depends on factors such as body weight, it is not known if these factors have an effect on the activity of prasugrel or ticagrelor. Thus, this study aimed to analyse factors associated with high residual platelet reactivity after administration of third generation P2Y12-antagonists compared to clopidogrel. In a single centre registry the antiplatelet effect of clopidogrel, prasugrel or ticagrelor was investigated by aggregometry in patients after MI. To assess the overall capacity of platelet aggregation whole blood was induced with thrombin receptor activating peptide (TRAP; 32 µM). To specifically quantify the effect of P2Y12-antagonists, blood was stimulated with 6.4 µM adenosine diphophosphate (ADP). Relative ADP induced aggregation (r-ADP-agg) was defined as the ADP-TRAP-ratio to reflect an individual degree of P2Y12-dependent platelet inhibition. Platelet function of 238 patients was analysed [clopidogrel (n = 58), prasugrel (n = 65), ticagrelor (n = 115)]. It was found that the r-ADP-agg correlated significantly with body weight in patients after clopidogrel administration (r = 0.423; p clopidogrel, platelet reactivity after administration of prasugrel or ticagrelor does not depend on body weight in patients after MI. Hence, our mechanistic data support the results of large clinical trials indicating that patients with high body weight do not need to be treated with increased doses of third generation P2Y12-antagonists to achieve sufficient platelet inhibition (registry for patients after myocardial infarction treated with antiplatelet agents; DRKS00003146).

  7. P2X7 receptor antagonists protect against N-methyl-D-aspartic acid-induced neuronal injury in the rat retina.

    Science.gov (United States)

    Sakamoto, Kenji; Endo, Kanako; Suzuki, Taishi; Fujimura, Kyosuke; Kurauchi, Yuki; Mori, Asami; Nakahara, Tsutomu; Ishii, Kunio

    2015-06-05

    Activation of N-methyl-d-aspartic acid (NMDA) receptors followed by a large Ca(2+) influx is thought to be a mechanism of glaucoma-induced neuronal cell death. It is possible that damage-associated molecular patterns leak from injured cells, such as adenosine triphosphate, causing retinal ganglion cell death in glaucoma. In the present study, we histologically investigated whether antagonists of the P2X7 receptor protected against NMDA-induced retinal injury in the rat in vivo. Under ketamine/xylazine anesthesia, male Sprague-Dawley rats were subjected to intravitreal injection of NMDA. We used A438079 (3-(5-(2,3-dichlorophenyl)-1H-tetrazol-1-yl)methyl pyridine) and brilliant blue G as P2X7 receptor antagonists. Upon morphometric evaluation 7 days after an intravitreal injection (200 nmol/eye), NMDA-induced cell loss was apparent in the ganglion cell layer. Intravitreal A438079 (50 pmol/eye) simultaneously injected with NMDA and intraperitoneal brilliant blue G (50 mg/kg) administered just before the NMDA injection as well as 24 and 48h after significantly reduced cell loss. In addition, A438079 decreased the number of terminal deoxynucleotidyl transferase dUTP nick end labeling-positive cells 12h after NMDA injection. P2X7 receptors were immunolocalized in the ganglion cell layer and the inner and outer plexiform layers, whereas the immunopositive P2X7 receptor signal was not detected on the Iba1-positive microglial cells that infiltrated the retina 12h after NMDA injection. The present study shows that stimulation of the P2X7 receptor is involved in NMDA-induced histological damage in the rat retina in vivo. P2X7 receptor antagonists may be effective in preventing retinal diseases caused by glutamate excitotoxicity, such as glaucoma and retinal artery occlusion.

  8. The P2X7 receptor antagonist Brilliant Blue G reduces serum human interferon-γ in a humanized mouse model of graft-versus-host disease.

    Science.gov (United States)

    Geraghty, N J; Belfiore, L; Ly, D; Adhikary, S R; Fuller, S J; Varikatt, W; Sanderson-Smith, M L; Sluyter, V; Alexander, S I; Sluyter, R; Watson, D

    2017-10-01

    Graft-versus-host disease (GVHD) remains a major problem after allogeneic haematopoietic stem cell transplantation, a curative therapy for haematological malignancies. Previous studies have demonstrated a role for the adenosine triphosphate (ATP)-gated P2X7 receptor channel in allogeneic mouse models of GVHD. In this study, injection of human peripheral blood mononuclear cells (PBMCs) into immunodeficient non-obese diabetic-severe combined immunodeficiency-interleukin (NOD-SCID-IL)-2Rγ(null) (NSG) mice established a humanized mouse model of GVHD. This model was used to study the effect of P2X7 blockade in this disease. From five weeks post-PBMC injection, humanized mice exhibited clinical signs and histopathology characteristic of GVHD. The P2X7 antagonist, Brilliant Blue G (BBG), blocked ATP-induced cation uptake into both murine and human cells in vitro. Injection of BBG (50 mg/kg) into NSG mice did not affect engraftment of human leucocytes (predominantly T cells), or the clinical score and survival of mice. In contrast, BBG injection reduced circulating human interferon (IFN)-γ significantly, which was produced by human CD4(+) and CD8(+) T cells. BBG also reduced human T cell infiltration and apoptosis in target organs of GVHD. In conclusion, the P2X7 antagonist BBG reduced circulating IFN-γ in a humanized mouse model of GVHD supporting a potential role for P2X7 to alter the pathology of this disease in humans. © 2017 British Society for Immunology.

  9. From ATP to AZD6140: the discovery of an orally active reversible P2Y12 receptor antagonist for the prevention of thrombosis.

    Science.gov (United States)

    Springthorpe, Brian; Bailey, Andrew; Barton, Patrick; Birkinshaw, Timothy N; Bonnert, Roger V; Brown, Roger C; Chapman, David; Dixon, John; Guile, Simon D; Humphries, Robert G; Hunt, Simon F; Ince, Francis; Ingall, Anthony H; Kirk, Ian P; Leeson, Paul D; Leff, Paul; Lewis, Richard J; Martin, Barrie P; McGinnity, Dermot F; Mortimore, Michael P; Paine, Stuart W; Pairaudeau, Garry; Patel, Anil; Rigby, Aaron J; Riley, Robert J; Teobald, Barry J; Tomlinson, Wendy; Webborn, Peter J H; Willis, Paul A

    2007-11-01

    Starting from adenosine triphosphate (ATP), the identification of a novel series of P2Y(12) receptor antagonists and exploitation of their SAR is described. Modifications of the acidic side chain and the purine core and investigation of hydrophobic substituents led to a series of neutral molecules. The leading compound, 17 (AZD6140), is currently in a large phase III clinical trial for the treatment of acute coronary syndromes and prevention of thromboembolic clinical sequelae.

  10. The impact of P2X7 receptor antagonist, brilliant blue G on graft-versus-host disease in mice after allogeneic hematopoietic stem cell transplantation.

    Science.gov (United States)

    Zhong, Xiaomin; Zhu, Feng; Qiao, Jianlin; Zhao, Kai; Zhu, Shengyun; Zeng, Lingyu; Chen, Xiaofei; Xu, Kailin

    2016-12-01

    The purpose of this study was to investigate the role of P2X7 on liver inflammation in mice after HSCT. Hematopoietic stem cells obtained from C57BL/6 mice were administrated into BALB/c mice to establish GVHD model. On day 7, 14, 21 and 28 after HSCT, mice received P2X7R antagonist brilliant blue G (BBG) or not were sacrificed for analysis of weight loss, liver inflammation, cytokine secretion, P2X7, NLRP3 expression as well as caspase-1 activation. Liver inflammation with neutrophils and macrophases infiltration as well as weight loss increase was present after HSCT, but improved after administration with high dose of BBG compared with lower dose. High dose of P2X7R inhibitor administration after HSCT previously reduced levels of IL-1β, IL-18, caspase-1, NLRP3 as well as P2X7, and the level of alanine transaminase (ALT) and the ratio of aspartate amino transferase (AST)/ALT compared with that receiving low dose of BBG. Meanwhile, P2X7R blockage also reduced infiltration of macrophages and neutrophils and levels of CXCL8 and CCL2 in peripheral blood as well as improved liver function. In conclusion, blockage of P2X7R by BBG exerts a protective effect on GVHD post HSCT and improves liver function suggesting that this receptor could be considered as an attractive target for treatment of GVHD. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. An assessment of the antagonistic activity of reactive blue 2 at P1- and P2-purinoceptors: supporting evidence for purinergic innervation of the rabbit portal vein.

    Science.gov (United States)

    Reilly, W M; Saville, V L; Burnstock, G

    1987-08-04

    A comparison of the effect of the putative adenosine 5'-triphosphate (ATP) antagonist, reactive blue 2, was made on the inhibitory responses to exogenous purines and non-adrenergic, non-cholinergic nerve stimulation in the rabbit portal vein, a preparation possessing both P1- and P2Y-purinoceptors, and on the excitatory responses to alpha, beta-methylene ATP in the rat portal vein where P2X-purinoceptors are present. In the ergotamine-contracted rabbit portal vein, ATP, adenosine and isoprenaline induced concentration-dependent relaxations. Reactive blue 2 (10-50 microM) produced a 2-9-fold shift to the right of the concentration-response curve to ATP, while the responses to adenosine and isoprenaline were not significantly altered. The inhibition of ATP assessed in the concentration-response curves appeared to be non-competitive. Electrical field stimulation of the ergotamine-contracted rabbit portal vein produced frequency-dependent relaxations that were abolished following incubation with tetrodotoxin (1 microM) and were inhibited by reactive blue 2 (30-50 microM), in a concentration-dependent manner. The rat portal vein contracted in response to the application of exogenous noradrenaline and alpha, beta-methylene ATP. Responses to both alpha, beta-methylene ATP (a P2X-purinoceptor agonist) and noradrenaline were not significantly inhibited by concentrations of reactive blue 2 that produced inhibition of the P2Y-mediated responses of the rabbit portal vein. In conclusion, it is suggested that reactive blue 2 is a non-competitive P2Y-purinoceptor antagonist, although the drug has a narrow range of activity and non-specific side effects become apparent at high concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

  12. Antagonists and the purinergic nerve hypothesis: 2, 2'-pyridylisatogen tosylate (PIT), an allosteric modulator of P2Y receptors. A retrospective on a quarter century of progress.

    Science.gov (United States)

    Spedding, M; Menton, K; Markham, A; Weetman, D F

    2000-07-01

    2,2'-Pyridylisatogen tosylate (PIT) is a selective antagonist of P2Y responses in smooth muscle and does not antagonise the effects of adenosine. Responses to purinergic nerve stimulation are resistant to PIT. PIT is an allosteric modulator of responses to ATP in recombinant P2Y(1) receptors expressed in Xenopus oocytes with potentiation of ATP at low concentrations (0.1-10 microM) and antagonism at higher ones (>10 microM). A radioligand binding profile showed that PIT did not interact with any other receptors, with the exception of low affinity for the adenosine A(1) receptor (pK(i), 5.3). The compound recognises purine sites and then may cause irreversible binding to sulfhydryl groups following prolonged incubation or high concentrations. PIT is a potent spin trapper.

  13. Graft-Infiltrating Macrophages Adopt an M2 Phenotype and Are Inhibited by Purinergic Receptor P2X7 Antagonist in Chronic Rejection.

    Science.gov (United States)

    Wu, C; Zhao, Y; Xiao, X; Fan, Y; Kloc, M; Liu, W; Ghobrial, R M; Lan, P; He, X; Li, X C

    2016-09-01

    Macrophages exhibit diverse phenotypes and functions; they are also a major cell type infiltrating chronically rejected allografts. The exact phenotypes and roles of macrophages in chronic graft loss remain poorly defined. In the present study, we used a mouse heart transplant model to examine macrophages in chronic allograft rejection. We found that treatment of C57BL/6 mice with CTLA4 immunoglobulin fusion protein (CTLA4-Ig) prevented acute rejection of a Balb/c heart allograft but allowed chronic rejection to develop over time, characterized by prominent neointima formation in the graft. There was extensive macrophage infiltration in the chronically rejected allografts, and the graft-infiltrating macrophages expressed markers associated with M2 cells but not M1 cells. In an in vitro system in which macrophages were polarized into either M1 or M2 cells, we screened phenotypic differences between M1 and M2 cells and identified purinergic receptor P2X7 (P2x7r), an adenosine triphosphate (ATP)-gated ion channel protein that was preferentially expressed by M2 cells. We further showed that blocking the P2x7r using oxidized ATP (oATP) inhibited M2 induction in a dose-dependent fashion in vitro. Moreover, treatment of C57BL/6 recipients with the P2x7r antagonist oATP, in addition to CTLA4-Ig treatment, inhibited graft-infiltrating M2 cells, prevented transplant vasculopathy, and induced long-term heart allografts survival. These findings highlight the importance of the P2x7r-M2 axis in chronic rejection and establish P2x7r as a potential therapeutic target in suppression of chronic rejection.

  14. Systemic administration of an antagonist of the ATP-sensitive receptor P2X7 improves recovery after spinal cord injury.

    Science.gov (United States)

    Peng, Weiguo; Cotrina, Maria L; Han, Xiaoning; Yu, Hongmei; Bekar, Lane; Blum, Livnat; Takano, Takahiro; Tian, Guo-Feng; Goldman, Steven A; Nedergaard, Maiken

    2009-07-28

    Traumatic spinal cord injury is characterized by an immediate, irreversible loss of tissue at the lesion site, as well as a secondary expansion of tissue damage over time. Although secondary injury should, in principle, be preventable, no effective treatment options currently exist for patients with acute spinal cord injury (SCI). Excessive release of ATP by the traumatized tissue, followed by activation of high-affinity P2X7 receptors, has previously been implicated in secondary injury, but no clinically relevant strategy by which to antagonize P2X7 receptors has yet, to the best of our knowledge, been reported. Here we have tested the neuroprotective effects of a systemically administered P2X7R antagonist, Brilliant blue G (BBG), in a weight-drop model of thoracic SCI in rats. Administration of BBG 15 min after injury reduced spinal cord anatomic damage and improved motor recovery without evident toxicity. Moreover, BBG treatment directly reduced local activation of astrocytes and microglia, as well as neutrophil infiltration. These observations suggest that BBG not only protected spinal cord neurons from purinergic excitotoxicity, but also reduced local inflammatory responses. Importantly, BBG is a derivative of a commonly used blue food color (FD&C blue No. 1), which crosses the blood-brain barrier. Systemic administration of BBG may thus comprise a readily feasible approach by which to treat traumatic SCI in humans.

  15. P2Y6 Receptor Antagonist MRS2578 Inhibits Neutrophil Activation and Aggregated Neutrophil Extracellular Trap Formation Induced by Gout-Associated Monosodium Urate Crystals.

    Science.gov (United States)

    Sil, Payel; Hayes, Craig P; Reaves, Barbara J; Breen, Patrick; Quinn, Shannon; Sokolove, Jeremy; Rada, Balázs

    2017-01-01

    Human neutrophils (polymorphonuclear leukocytes [PMNs]) generate inflammatory responses within the joints of gout patients upon encountering monosodium urate (MSU) crystals. Neutrophil extracellular traps (NETs) are found abundantly in the synovial fluid of gout patients. The detailed mechanism of MSU crystal-induced NET formation remains unknown. Our goal was to shed light on possible roles of purinergic signaling and neutrophil migration in mediating NET formation induced by MSU crystals. Interaction of human neutrophils with MSU crystals was evaluated by high-throughput live imaging using confocal microscopy. We quantitated NET levels in gout synovial fluid supernatants and detected enzymatically active neutrophil primary granule enzymes, myeloperoxidase, and human neutrophil elastase. Suramin and PPADS, general P2Y receptor blockers, and MRS2578, an inhibitor of the purinergic P2Y6 receptor, blocked NET formation triggered by MSU crystals. AR-C25118925XX (P2Y2 antagonist) did not inhibit MSU crystal-stimulated NET release. Live imaging of PMNs showed that MRS2578 represses neutrophil migration and blocked characteristic formation of MSU crystal-NET aggregates called aggregated NETs. Interestingly, the store-operated calcium entry channel inhibitor (SK&F96365) also reduced MSU crystal-induced NET release. Our results indicate that the P2Y6/store-operated calcium entry/IL-8 axis is involved in MSU crystal-induced aggregated NET formation, but MRS2578 could have additional effects affecting PMN migration. The work presented in the present study could lead to a better understanding of gouty joint inflammation and help improve the treatment and care of gout patients.

  16. [3H]A-804598 ([3H]2-cyano-1-[(1S)-1-phenylethyl]-3-quinolin-5-ylguanidine) is a novel, potent, and selective antagonist radioligand for P2X7 receptors.

    Science.gov (United States)

    Donnelly-Roberts, Diana L; Namovic, Marian T; Surber, Bruce; Vaidyanathan, Srirajan X; Perez-Medrano, Arturo; Wang, Ying; Carroll, William A; Jarvis, Michael F

    2009-01-01

    ATP-sensitive P2X7 receptors are localized on cells of immunological origin including peripheral macrophages and glial cells in the CNS. Activation of P2X7 receptors leads to rapid changes in intracellular calcium concentrations, release of the pro-inflammatory cytokine IL-1beta, and following prolonged agonist exposure, the formation of cytolytic pores in plasma membranes. Data from gene knockout studies and recently described selective antagonists indicate a role for P2X7 receptor activation in inflammation and pain. While several species selective P2X7 antagonists exist, A-804598 represents a structurally novel, competitive, and selective antagonist that has equivalent high affinity at rat (IC50 = 10 nM), mouse (IC50 = 9 nM) and human (IC50 = 11 nM) P2X7 receptors. A-804598 also potently blocked agonist stimulated release of IL-1beta and Yo-Pro uptake from differentiated THP-1 cells that natively express human P2X7 receptors. A-804598 was tritiated ([3H]A-804598; 8.1Ci/mmol) and utilized to study recombinant rat P2X7 receptors expressed in 1321N1 cells. [3H]A-804598 labeled a single class of high affinity binding sites (Kd=2.4 nM and apparent Bmax=0.56 pmol/mg). No specific binding was observed in untransfected 1321N1 cells. The pharmacological profile for P2X antagonists to inhibit [3H]A-804598 binding correlated with their ability to block functional activation of P2X7 receptors (r=0.95, PP2X7 receptors described to date and [3H]A-804598 is a high affinity antagonist radioligand that specifically labels rat P2X7 receptors.

  17. α-hemolysin from Escherichia coli uses endogenous amplification through P2X receptor activation to induce hemolysis

    DEFF Research Database (Denmark)

    Skals, Marianne Gerberg; Jørgensen, Niklas R; Leipziger, Jens Georg

    2009-01-01

    ) antagonists (PPADS, suramin) and ATP scavengers (apyrase, hexokinase) concentration dependently inhibited HlyA-induced lysis of equine, murine, and human erythrocytes. The pattern of responsiveness to more selective P2-antagonists implies that both P2X(1) and P2X(7) receptors are involved in Hly...... frequently produce virulence factors such as alpha-hemolysin (HlyA), which causes hemolysis by forming pores in the erythrocyte membrane. The present study reveals that this pore formation triggers purinergic receptor activation to mediate the full hemolytic action. Non-selective ATP-receptor (P2......A-induced hemolysis in all three species. In addition, our results also propose a role for the pore protein pannexin1 in HlyA-induced hemolysis, as non-selective inhibitors of this channel significantly reduced hemolysis in the three species. In conclusion, activation of P2X receptors and possibly also pannexins...

  18. Optimal timing of initiation of oral P2Y12-receptor antagonist therapy in patients with non-ST elevation acute coronary syndromes. Lessons learnt from the ACCOAST-trial

    DEFF Research Database (Denmark)

    Zeymer, Uwe; Montalescot, Gilles; Ardissino, Diego;

    2016-01-01

    The optimal time-point of the initiation of P2Y12 antagonist therapy in patients with non-ST elevation acute coronary syndromes (NTSE-ACS) is still a matter of debate. European guidelines recommend P2Y12 as soon as possible after first medical contact. However, the only trial which compared the two...... strategies did not demonstrate any benefit of pre-treatment with prasugrel before angiography compared to starting therapy after angiography and just prior to percutaneous coronary intervention (PCI). This paper summarizes the results of pharmacodynamic and previous studies, and gives recommendations...... for the initiation of P2Y12 antagonist therapy in NSTE-ACS in different clinical situations....

  19. P2 purinoceptors: Renal pathophysiology and therapeutic potential.

    Science.gov (United States)

    Booth, John W R; Tam, Frederick W K; Unwin, Robert J

    2012-08-01

    P2 purinoceptors, categorized into P2X and P2Y receptors, bind extracellular ATP and related di- and tri-phosphate nucleotides and are expressed throughout the kidney. P2X receptors are non-selective cation channels and P2Y receptors are metabotropic G protein-coupled receptors. Both families may couple to a range of second messenger systems and provoke outcomes including cell proliferation, cytokine secretion, membrane channel regulation and cell death. The cellular response to ATP release may vary widely and depends on both the pattern of local receptor expression and the action of ectonucleotidases altering agonist availability, creating a finely tuned network. P2 signaling participates in disparate physiological processes, including control of water and solute transport and autoregulation of renal blood flow. Given the ubiquity, complexity and diversity of the P2 network, it is not surprising that P2 signaling also contributes to mechanisms of renal disease. This review summarizes the current evidence for P2 receptor involvement in a range of kidney diseases, and highlights areas that may lead to potential therapeutic advances. Particular attention is paid to the pro-inflammatory P2X7 receptor, currently at the heart of renal P2 pathophysiology and for which selective receptor antagonists are now available.

  20. Modulation of P2 receptors on pancreatic β-cells by agonists and antagonists: a molecular target for type 2 diabetes treatment.

    Science.gov (United States)

    Pacheco, Paulo Anastácio Furtado; Ferreira, Leonardo Gomes Braga; Alves, Luiz Anastacio; Faria, Robson Xavier

    2013-05-01

    Morbidity and mortality from diabetes mellitus (DM) are serious worldwide concerns. By the year 2030, the estimated number of diabetic patients will reach a staggering 439 million worldwide. Diabetes mellitus type 2 (DM2), which involves disturbances in both insulin secretion and resistance, is the most common form of diabetes and affects approximately 5 to 7% of the world's population. When a patient with DM2 cannot regulate his or her blood glucose levels through diet, weight loss, or exercise, oral medications, such as hypoglycemic agents (i.e., sulphonylureas, biguanides, alpha glucosidase inhibitors and thiazolidinediones), are crucial. Here, we discuss some physiological aspects of P2 receptors on pancreatic β-cells, which express a variety of P2 receptor isoforms. These receptors enhance glucose-dependent insulin release. In addition, we speculate on the potential of purinergic compounds as novel or additional treatments for Type 2 Diabetes mellitus.

  1. Antagonistic effect of Na+ and Mg2+ on P2z purinoceptor-associated pores in dibutyryl cyclic AMP-differentiated NG108-15 cells.

    Science.gov (United States)

    Song, S L; Chueh, S H

    1996-10-01

    The effect of replacement of extracellular Na+ with N-methyl-D-glucamine (NMG) on P2 receptor signaling pathways was investigated in dibutyryl cyclic AMP-differentiated NG108-15, cells. Benzoylbenzoic ATP (BzATP) dose-dependently increased the cytosolic Ca2+ concentration ([Ca2+]i) with an EC50 value of 230 microM. Replacement of Na+ with NMG as well as removal of Mg2+ from the bathing buffer potentiated ethidium bromide uptake, [Ca2+]i increase, and 45Ca2+ uptake in response to ATP or BzATP. In contrast, in the presence of 5 mM Mg2+ to limit the amount of ATP4-, replacement of Na+ with NMG had no effect on the ATP-induced [Ca2+]i increase but caused a markedly larger [Ca2+]i increase when the calculated concentration of ATP4- was > 10 microM. The calculated EC50 value for ATP4- stimulation of the [Ca2+]i increase was 23 microM in NG108-15 cells. In vascular smooth muscle cells, intracellular Ca2+ release was the major pathway for the ATP-induced [Ca2+]i increase; both removal of Mg2+ and replacement of Na+ with NMG did not affect the action of ATP. These data suggest that ATP(4-)-promoted pores are antagonized by Na+ and Mg2+ in dibutyryl cyclic AMP-differentiated NG108-15 cells.

  2. P2X7受体拮抗剂A438079对肠易激综合征结肠扩张刺激大鼠DCN核团中P2X7、OX42、IL-1β、P38及骶髓后角中CGRP表达的影响%Effect of P2X7 receptor antagonist A438079 on expression of P2X7,OX42,IL-1β,P38 in dorsal commissural nucleus and CGRP expression in dorsal horn of sacral segment of spinal cord in rats with irritable bowel syndrome

    Institute of Scientific and Technical Information of China (English)

    朱琳; 章鹏宇; 黄裕新; 王景杰

    2012-01-01

    目的 探讨P2X7特异性受体拮抗剂A438079对肠易激综合征(irritable bowel syndrome,IBS)致内脏高敏感化大鼠在结肠扩张刺激状态时,骶髓后联合核(dorsal commissural nucleus,DCN)中P2X7、OX42、IL-1β、P38及脊髓背角中CGRP表达的变化,为探讨IBS内脏敏化的神经机制提供理论依据.方法 以15只旋毛虫感染大鼠建立肠易激综合征模型,随机分为三组,总共分为:B.IBS大鼠结肠扩张刺激组(n=5)、C.IBS大鼠鞘内注射0.9%生理盐水后结肠扩张刺激组(n=5)、D.IBS大鼠鞘内注射A438079后结肠扩张刺组(n=5).另外以5只正常大鼠作正常大鼠结肠扩张刺激组(n=5)、.采用免疫荧光组织化学方法观察大鼠DCN中P2X7、OX42、IL-1β、P38及脊髓后角中CGRP表达变化.结果 与B组IBS扩张刺激组相比较,D组鞘内注射拮抗剂A438079后在结肠扩张刺激时IBS大鼠DCN核团中P2X7、OX42、IL-1β、P38及骶髓后角中CGRP的表达量均明显下降(P<0.01).结论 P2X7受体在IBS致内脏敏化过程中广泛参与,并可能起重要作用.%Objective To explore the effect of A438079, a P2X7 receptor antagonist, on expression of P2X7 , 0x42, IL-1 β, P38 in dorsal commissural nucleus and calcitonin gene related peptide( CGRP ) in dorsal horn of sacral segment of spinal cord in rats with irritable bowel syndrome ( IBS ) induced by the stimulation of colorectal distention, and to provide a theoretical evidence in the prevention and treatment of IBS. Methods Fifteen rats were gavaged with the Trichinella spiralis to establish the IBS model, and then were divided into three groups: IBS + colon distension group ( B ), IBS + colon distension + intrathecal injection of saline ( C ), and IBS + colon distension + intrathecal injection of A438079( D ). Five normal rats with colon distension were chosen as control group. Immunofluorescent staining method was used to observe the expression of P2X7,OX42,I L-1β,P38 in neurons of DCN and CGRP expression in

  3. Anoxic depolarization of hippocampal astrocytes: possible modulation by P2X7 receptors.

    Science.gov (United States)

    Leichsenring, Anna; Riedel, Thomas; Qin, Ying; Rubini, Patrizia; Illes, Peter

    2013-01-01

    Current responses from CA1 neurons and stratum oriens astrocytes were recorded from hippocampal brain slices by means of the whole-cell patch-clamp technique. Anoxic depolarization (AD) was induced by an oxygen/glucose-deprived (OGD) medium also containing sodium iodoacetate and antimycin, in order to block glycolysis and oxidative phosphorylation, respectively. Anoxic depolarization has been reported to be due to the sudden increase of the extracellular K(+) concentration and the accompanying explosive rise in glutamate concentration. We asked ourselves whether the release of ATP activating P2X7 receptors is also involved in the AD. Although, the AD was evoked in absolute synchrony in neurons and astrocytes, and the NMDA receptor antagonistic AP-5 depressed these responses, neither the non-selective P2 receptor antagonist PPADS, nor the highly selective P2X7 receptor antagonist A438079 interfered with the AD or its delay time in neurons/astrocytes after inducing chemical hypoxia. However, A438079, but not PPADS increased in astrocytes the slow inward current observed in a hypoxic medium. It is concluded that ATP co-released with glutamate by hypoxic stimulation has only a minor function in the present brain slice system.

  4. Structural basis for subtype-specific inhibition of the P2X7 receptor

    Energy Technology Data Exchange (ETDEWEB)

    Karasawa, Akira; Kawate, Toshimitsu

    2016-12-09

    The P2X7 receptor is a non-selective cation channel activated by extracellular adenosine triphosphate (ATP). Chronic activation of P2X7 underlies many health problems such as pathologic pain, yet we lack effective antagonists due to poorly understood mechanisms of inhibition. Here we present crystal structures of a mammalian P2X7 receptor complexed with five structurally-unrelated antagonists. Unexpectedly, these drugs all bind to an allosteric site distinct from the ATP-binding pocket in a groove formed between two neighboring subunits. This novel drug-binding pocket accommodates a diversity of small molecules mainly through hydrophobic interactions. Functional assays propose that these compounds allosterically prevent narrowing of the drug-binding pocket and the turret-like architecture during channel opening, which is consistent with a site of action distal to the ATP-binding pocket. These novel mechanistic insights will facilitate the development of P2X7-specific drugs for treating human diseases.

  5. A novel gliotic P2 receptor mediating cyclooxygenase-2 induction in rat and human astrocytes.

    Science.gov (United States)

    Brambilla, R; Ceruti, S; Malorni, W; Cattabeni, F; Abbracchio, M P

    2000-07-01

    In astrocytic cultures maintained in vitro, a brief challenge with the ATP analog alpha,beta methyleneATP (alpha,betameATP) results, 3 days later, in marked elongation of astrocytic processes, an event that resembles the astrocytic hypertrophy known to occur in vivo during reactive astrogliosis. alpha,beta meATP-induced effects were observed in primary astrocytes obtained from both rat striatum and cortex (a brain area highly involved in chronic neurodegenerative pathologies), as well as in human astrocytoma cells (ADF cells). Purine-induced gliosis could be reversed by the non-selective P2X/P2Y receptor antagonist pyridoxalphosphate-6-azophenyl-2', 4'-disulphonic acid (PPADS), but not by oxidized ATP (an antagonist of the P2X(7) receptor), in line with previous studies of our laboratory suggesting the involvement of a P2Y receptor subtype. Induction of reactive gliosis was preceded by increased expression of cyclooxygenase-2 (COX-2), an enzyme whose excessive activation has been implicated in both acute and chronic neurodegenerative diseases. The selective COX-2 inhibitor NS-398 prevented both purine-induced astrogliosis and the associated COX-2 induction, suggesting that inhibition of the transcription of the COX-2 gene may also contribute to the anti-inflammatory properties of this agent. Significant blockade of both alpha,beta meATP-mediated reactive gliosis and COX-2 induction was also observed with PPADS. These data suggest that COX-2 mediates P2Y receptor-induced reactive astrogliosis, and that antagonists selective for this receptor subtype may represent a novel class of anti-inflammatory agents of potential interest in acute and chronic neurological disorders characterized by an inflammatory component and reactive gliosis.

  6. Feasibility study of B16 melanoma therapy using oxidized ATP to target purinergic receptor P2X7.

    Science.gov (United States)

    Hattori, Fumie; Ohshima, Yasuhiro; Seki, Shizuka; Tsukimoto, Mitsutoshi; Sato, Mitsuru; Takenouchi, Takato; Suzuki, Akina; Takai, Erina; Kitani, Hiroshi; Harada, Hitoshi; Kojima, Shuji

    2012-11-15

    The P2X7 receptor is not only involved in cell proliferation, but also acts as an adenosine 5'-triphosphate (ATP)-gated non-selective channel, and its expression is increased in human melanoma. An irreversible antagonist of P2X7, such as oxidized ATP (oxATP), might block P2X7 receptor-mediated ATP release and proliferative signaling. Therefore, we carried out basic studies to test this idea and to examine the feasibility of using oxATP to treat B16 melanoma. We first found that low-pH conditions (mimicking the hypoxia and acidosis commonly seen in solid tumors) induced P2X7 receptor-mediated ATP release from B16 melanoma cells. Then, we compared the proliferation rates of B16 melanoma wild-type cells and B16 P2X7 receptor-knockdown clone (P2X7-KDC) cells in the presence of P2X7 agonists. The proliferation rate, as well as the ATP release, of agonist-treated P2X7-KDC cells was lower than that of agonist-treated wild-type cells. Next, the effect of P2X7 antagonist oxATP on B16 melanoma cell growth was examined in vitro and in vivo. oxATP significantly decreased B16 melanoma cell proliferation in vitro, and also significantly inhibited tumor growth in B16 melanoma-bearing mice. These data indicate that extracellularly released ATP may serve as an intercellular signaling molecule. We propose that the P2X7 receptor is a promising target for treatment of solid tumors.

  7. Single administration of p2TA (AB103, a CD28 antagonist peptide, prevents inflammatory and thrombotic reactions and protects against gastrointestinal injury in total-body irradiated mice.

    Directory of Open Access Journals (Sweden)

    Salida Mirzoeva

    Full Text Available The goal of this study was to elucidate the action of the CD28 mimetic peptide p2TA (AB103 that attenuates an excessive inflammatory response in mitigating radiation-induced inflammatory injuries. BALB/c and A/J mice were divided into four groups: Control (C, Peptide (P; 5 mg/kg of p2TA peptide, Radiation (R; total body irradiation with 8 Gy γ-rays, and Radiation + Peptide (RP; irradiation followed by p2TA peptide 24 h later. Gastrointestinal tissue damage was evaluated by analysis of jejunum histopathology and immunohistochemistry for cell proliferation (Cyclin D1 and inflammation (COX-2 markers, as well as the presence of macrophages (F4/80. Pro-inflammatory cytokines IL-6 and KC as well as fibrinogen were quantified in plasma samples obtained from the same mice. Our results demonstrated that administration of p2TA peptide significantly reduced the irradiation-induced increase of IL-6 and fibrinogen in plasma 7 days after exposure. Seven days after total body irradiation with 8 Gy of gamma rays numbers of intestinal crypt cells were reduced and villi were shorter in irradiated animals compared to the controls. The p2TA peptide delivery 24 h after irradiation led to improved morphology of villi and crypts, increased Cyclin D1 expression, decreased COX-2 staining and decreased numbers of macrophages in small intestine of irradiated mice. Our study suggests that attenuation of CD28 signaling is a promising therapeutic approach for mitigation of radiation-induced tissue injury.

  8. P2 X7 receptor and renal diseases%P2 X7受体和肾脏疾病

    Institute of Scientific and Technical Information of China (English)

    刘辉; 纪旭

    2015-01-01

    P2 X7 receptor is a member of ATP-gated non-selective cation channels;and is one subtype family of the P2X purinergic receptor.Signaling pathways of P2X7 receptor couple with several key inflammatory molecules including IL-1β;IL-6 and COX-2;which suggests that P2 X7 receptor plays a key role in the development of dis-eases via increased inflammation;indicating its potential as a novel therapeutic target.Recent studies show that P2 X7 receptor has a relationship with renal diseases.This article reviews the effect of P2 X7 receptor on renal diseases and its mechanism.P2 X7 receptor may be a new drug target;and its selectivity antagonist may be a new therapeutic agent for the treatment of renal diseases.%P2X7受体是三磷酸腺苷(ATP)门控阳离子通道受体,是嘌呤受体P2X家族受体亚型之一。 P2X7受体信号通路与IL-1β、IL-6、COX-2等多种炎症因子的生成和释放相关,在多种疾病的发病过程中起到了至关重要的作用。目前以此受体为治疗靶点的P2 X7受体拮抗剂已进入临床试验阶段,表现出良好的安全性和疗效。最新研究表明P2 X7受体与多种肾脏疾病有关,P2X7受体拮抗剂具有潜在的肾脏疾病治疗作用。本文综述P2X7受体在肾脏疾病中的作用及其可能的作用机制,以期为肾脏疾病治疗的新靶点和新策略提供理论依据。

  9. Multiple P2Y receptors couple to calcium-dependent, chloride channels in smooth muscle cells of the rat pulmonary artery

    Directory of Open Access Journals (Sweden)

    Gurney Alison M

    2005-10-01

    Full Text Available Abstract Background Uridine 5'-triphosphate (UTP and uridine 5'-diphosphate (UDP act via P2Y receptors to evoke contraction of rat pulmonary arteries, whilst adenosine 5'-triphosphate (ATP acts via P2X and P2Y receptors. Pharmacological characterisation of these receptors in intact arteries is complicated by release and extracellular metabolism of nucleotides, so the aim of this study was to characterise the P2Y receptors under conditions that minimise these problems. Methods The perforated-patch clamp technique was used to record the Ca2+-dependent, Cl- current (ICl,Ca activated by P2Y receptor agonists in acutely dissociated smooth muscle cells of rat small (SPA and large (LPA intrapulmonary arteries, held at -50 mV. Contractions to ATP were measured in isolated muscle rings. Data were compared by Student's t test or one way ANOVA. Results ATP, UTP and UDP (10-4M evoked oscillating, inward currents (peak = 13–727 pA in 71–93% of cells. The first current was usually the largest and in the SPA the response to ATP was significantly greater than those to UTP or UDP (P -1 and changed little during agonist application. The non-selective P2 receptor antagonist suramin (10-4M abolished currents evoked by ATP in SPA (n = 4 and LPA (n = 4, but pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS (10-4M, also a non-selective P2 antagonist, had no effect (n = 4, 5 respectively. Currents elicited by UTP (n = 37 or UDP (n = 14 were unaffected by either antagonist. Contractions of SPA evoked by ATP were partially inhibited by PPADS (n = 4 and abolished by suramin (n = 5. Both antagonists abolished the contractions in LPA. Conclusion At least two P2Y subtypes couple to ICl,Ca in smooth muscle cells of rat SPA and LPA, with no apparent regional variation in their distribution. The suramin-sensitive, PPADS-resistant site activated by ATP most resembles the P2Y11 receptor. However, the suramin- and PPADS-insensitive receptor activated by UTP and UDP

  10. 4-((R)-2-{[6-((S)-3-Methoxypyrrolidin-1-yl)-2-phenylpyrimidine-4-carbonyl]amino}-3-phosphonopropionyl)piperazine-1-carboxylic Acid Butyl Ester (ACT-246475) and Its Prodrug (ACT-281959), a Novel P2Y12 Receptor Antagonist with a Wider Therapeutic Window in the Rat Than Clopidogrel.

    Science.gov (United States)

    Caroff, Eva; Hubler, Francis; Meyer, Emmanuel; Renneberg, Dorte; Gnerre, Carmela; Treiber, Alexander; Rey, Markus; Hess, Patrick; Steiner, Beat; Hilpert, Kurt; Riederer, Markus A

    2015-12-10

    Recent post hoc analyses of several clinical trials with P2Y12 antagonists showed the need for new molecules being fully efficacious as antiplatelet agents and having a reduced propensity to cause major bleeding. We have previously reported the discovery of the 2-phenylpyrimidine-4-carboxamide analogs as P2Y12 antagonists with nanomolar potency in the disease-relevant platelet aggregation assay in human plasma. Herein we present the optimization steps that led to the discovery of clinical candidate ACT-246475 (30d). The key step was the replacement of the carboxylic acid functionality by a phosphonic acid group which delivered the most potent molecules of the program. In addition, low in vivo clearance in rat and dog was achieved for the first time. Since the bioavailability of 30d was low in rat and dog, we developed the bis((isopropoxycarbonyl)oxy)methyl ester prodrug (ACT-281959, 45). Compound 30d showed efficacy in the rat ferric chloride thrombosis model when administered intravenously as parent or orally as its prodrug 45. Moreover, 30d displays a wider therapeutic window as compared to clopidogrel in the rat surgical blood loss model.

  11. P2X7受体阻断剂亮蓝G对氧化应激所致红细胞氧化损伤的保护机制%Protection mechanism of P2X7 receptor antagonist brilliant blue G to oxidative damage of erythrocyte

    Institute of Scientific and Technical Information of China (English)

    2016-01-01

    目的 探讨P2X7受体阻断剂亮蓝G(BBG)对偶氮二异丁脒盐酸盐(AAPH)所致红细胞氧化损伤的保护机制.方法 取雄性Wistar大鼠红细胞,配成体积分数6.25%的红细胞悬液,分为对照组、AAPH组、AAPH+ BBG组,对照组加入林格液1,AAPH组加入林格液1、AAPH液,AAPH+ BBG组加入林格液1、AAPH液及BBG液,分别将3组标本放入水浴恒温振荡器中孵育1.5h,检测比较3组标本的红细胞溶血率、渗透脆性及细胞内Ca2+浓度变化.结果 与对照组比较,AAPH组红细胞溶血率、渗透脆性及红细胞内Ca2+浓度显著增高(P<0.01);与AAPH组比较,AAPH+ BBG组红细胞溶血率、渗透脆性及红细胞内Ca2+浓度显著降低(P<0.05).结论 P2X7受体阻断剂BBG可抑制氧化应激所致红细胞Ca2+内流,降低红细胞的渗透脆性,从而抑制AAPH对红细胞造成的氧化损伤.

  12. α-hemolysin from Escherichia coli uses endogenous amplification through P2X receptor activation to induce hemolysis

    DEFF Research Database (Denmark)

    Skals, Marianne Gerberg; Jørgensen, Niklas R; Leipziger, Jens Georg

    2009-01-01

    Escherichia coli is the dominant facultative bacterium in the normal intestinal flora. E. coli is, however, also responsible for the majority of serious extraintestinal infections. There are distinct serotypical differences between facultative and invasive E. coli strains. Invasive strains freque...... augment hemolysis induced by the bacterial toxin, HlyA. These findings potentially have clinical perspectives as P2 antagonists may ameliorate symptoms during sepsis with hemolytic bacteria.......A-induced hemolysis in all three species. In addition, our results also propose a role for the pore protein pannexin1 in HlyA-induced hemolysis, as non-selective inhibitors of this channel significantly reduced hemolysis in the three species. In conclusion, activation of P2X receptors and possibly also pannexins...

  13. Saperi P2P

    Directory of Open Access Journals (Sweden)

    Salvatore Iaconesi

    2009-10-01

    Full Text Available Il paper presenta l'architettura filosofica e logica di un progetto ongoing per la creazione di un'infrastruttura peer to peer per la diffusione dei saperi. Tale infrastruttura p2p vuole essere la base per costruire un framework aperto e orizzontale, che ospiti pratiche innovative di creazione, condivisione e disseminazione di informazioni e conoscenza.

  14. Cardiomyocyte death induced by ischaemic/hypoxic stress is differentially affected by distinct purinergic P2 receptors.

    Science.gov (United States)

    Cosentino, Simona; Banfi, Cristina; Burbiel, Joachim C; Luo, Haijian; Tremoli, Elena; Abbracchio, Maria P

    2012-05-01

    Blood levels of extracellular nucleotides (e.g. ATP) are greatly increased during heart ischaemia, but, despite the presence of their specific receptors on cardiomyocytes (both P2X and P2Y subtypes), their effects on the subsequent myocardial damage are still unknown. In this study, we aimed at investigating the role of ATP and specific P2 receptors in the appearance of cell injury in a cardiac model of ischaemic/hypoxic stress. Cells were maintained in a modular incubator chamber in a controlled humidified atmosphere of 95% N(2) for 16 hrs in a glucose-free medium. In this condition, we detected an early increase in the release of ATP in the culture medium, which was followed by a massive increase in the release of cytoplasmic histone-associated-DNA-fragments, a marker of apoptosis. Addition of either apyrase, which degrades extracellular ATP, or various inhibitors of ATP release via connexin hemichannels fully abolished ischaemic/hypoxic stress-associated apoptosis. To dissect the role of specific P2 receptor subtypes, we used a combined approach: (i) non-selective and, when available, subtype-selective P2 antagonists, were added to cardiomyocytes before ischaemic/hypoxic stress; (ii) selected P2 receptors genes were silenced via specific small interfering RNAs. Both approaches indicated that the P2Y(2) and P2χ(7) receptor subtypes are directly involved in the induction of cell death during ischaemic/hypoxic stress, whereas the P2Y(4) receptor has a protective effect. Overall, these findings indicate a role for ATP and its receptors in modulating cardiomyocyte damage during ischaemic/hypoxic stress.

  15. Presynaptic P2 receptors?

    Science.gov (United States)

    Stone, T W; O'Kane, E M; Nikbakht, M R; Ross, F M

    2000-07-01

    Although the emphasis in ATP research has been on postjunctional receptors, there is also evidence for presynaptic receptors regulating transmitter release in the autonomic nervous system. Recent work has attempted to identify similar mechanisms in the central nervous system. Some of the existing results can be explained by the metabolism of nucleotides to adenosine or adenosine 5'-monophosphate (AMP). However, studies of presynaptic effects using sensitive electrophysiological tests such as paired-pulse interactions indicate that nucleotides can act at presynaptic sites, but that their effects may be mediated by a release of adenosine. Results are also described which indicate that, under some conditions, nucleotides can mediate phenomena such as long-term potentiation, which probably involves a significant presynaptic element. In part these effects may involve a nucleotide-induced release of adenosine and the simultaneous activation of P1 and P2 receptors.

  16. Procedures to characterize and study P2Z/P2X7 purinoceptor: flow cytometry as a promising practical, reliable tool

    Directory of Open Access Journals (Sweden)

    Nihei Oscar Kenji

    2000-01-01

    Full Text Available The expression of P2Z/P2X7 purinoceptor in different cell types is well established. This receptor is a member of the ionotropic P2X receptor family, which is composed by seven cloned receptor subtypes (P2X1 - P2X7. Interestingly, the P2Z/P2X7 has a unique feature of being linked to a non-selective pore which allows the passage of molecules up to 900 Da depending on the cell type. Early studies of P2Z/P2X7 purinoceptor were exclusively based on classical pharmacological studies but the recent tools of molecular biology have enriched the analysis of the receptor expression. The majority of assays and techniques chosen so far to study the expression of P2Z/P2X7 receptor explore directly or indirectly the effects of the opening of P2Z/P2X7 linked pore. In this review we describe the main techniques used to study the expression and functionality of P2Z/P2X7 receptor. Additionally, the increasing need and importance of a multifunctional analysis of P2Z/P2X7 expression based on flow cytometry technology is discussed, as well as the adoption of a more complete analysis of P2Z/P2X7 expression involving different techniques.

  17. P2伴侣

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    1.项目构成情况综合介绍: P2mate作为一款移动存储设备,是松下P2专业解决方案的一部分。音视频数据量巨大,而P2卡由于技术原因短期内无法将容量做的很大,所以需要一个超大容量价格又低(相对于P2卡)的暂时存储体,P2mate就是这个暂时存储体。体积大小适合于摄影师随身携带,壳体坚固能适应野外拍摄,能够存储20片以上的P2卡素材。

  18. Adenylate cyclase 5 coordinates the action of ADP, P2Y1, P2Y13 and ATP-gated P2X7 receptors on axonal elongation.

    Science.gov (United States)

    del Puerto, Ana; Díaz-Hernández, Juan-Ignacio; Tapia, Mónica; Gomez-Villafuertes, Rosa; Benitez, María José; Zhang, Jin; Miras-Portugal, María Teresa; Wandosell, Francisco; Díaz-Hernández, Miguel; Garrido, Juan José

    2012-01-01

    In adult brains, ionotropic or metabotropic purinergic receptors are widely expressed in neurons and glial cells. They play an essential role in inflammation and neurotransmission in response to purines secreted to the extracellular medium. Recent studies have demonstrated a role for purinergic receptors in proliferation and differentiation of neural stem cells although little is known about their role in regulating the initial neuronal development and axon elongation. The objective of our study was to investigate the role of some different types of purinergic receptors, P2Y1, P2Y13 and P2X7, which are activated by ADP or ATP. To study the role and crosstalk of P2Y1, P2Y13 and P2X7 purinergic receptors in axonal elongation, we treated neurons with specific agonists and antagonists, and we nucleofected neurons with expression or shRNA plasmids. ADP and P2Y1-GFP expression improved axonal elongation; conversely, P2Y13 and ATP-gated P2X7 receptors halted axonal elongation. Signaling through each of these receptor types was coordinated by adenylate cyclase 5. In neurons nucleofected with a cAMP FRET biosensor (ICUE3), addition of ADP or Blue Brilliant G, a P2X7 antagonist, increased cAMP levels in the distal region of the axon. Adenylate cyclase 5 inhibition or suppression impaired these cAMP increments. In conclusion, our results demonstrate a crosstalk between two metabotropic and one ionotropic purinergic receptor that regulates cAMP levels through adenylate cyclase 5 and modulates axonal elongation triggered by neurotropic factors and the PI3K-Akt-GSK3 pathway.

  19. Fuzzy C P2 spacetimes

    Science.gov (United States)

    Chaney, A.; Stern, A.

    2017-02-01

    Four-dimensional manifolds with changing signature are obtained by taking the large N limit of fuzzy C P2 solutions to a Lorentzian matrix model. The regions of Lorentzian signature give toy models of closed universes which exhibit cosmological singularities. These singularities are resolved at finite N , as the underlying C P2 solutions are expressed in terms of finite matrix elements.

  20. Role of P2Y12 Receptor in Thrombosis.

    Science.gov (United States)

    Zhang, Yaqi; Zhang, Si; Ding, Zhongren

    2017-01-01

    P2Y12 receptor is a 342 amino acid Gi-coupled receptor predominantly expressed on platelets. P2Y12 receptor is physiologically activated by ADP and inhibits adenyl cyclase (AC) to decrease cyclic AMP (cAMP) level, resulting in platelet aggregation. It also activates PI3 kinase (PI3K) pathway leading to fibrinogen receptor activation, and may protect platelets from apoptosis. Abnormalities of P2Y12 receptor include congenital deficiencies or high activity in diseases like diabetes mellitus (DM) and chronic kidney disease (CKD), exposing such patients to a prothrombotic condition. A series of clinical antiplatelet drugs, such as clopidogrel and ticagrelor, are designed as indirect or direct antagonists of P2Y12 receptor to reduce incidence of thrombosis mainly for patients of acute coronary syndrome (ACS) who are at high risk of thrombotic events. Studies on novel dual-/multi-target antiplatelet agents consider P2Y12 receptor as a promising part in combined targets. However, the clinical practical phenomena, such as "clopidogrel resistance" due to gene variations of cytochrome P450 or P2Y12 receptor constitutive activation, call for better antiplatelet agents. Researches also showed inverse agonist of P2Y12 receptor could play a better role over neutral antagonists. Personalized antiplatelet therapy is the most ideal destination for antiplatelet therapy in ACS patients with or without other underlying diseases like DM or CKD, however, there is still a long way to go.

  1. Antihyperalgesic effect of CB1 receptor activation involves the modulation of P2X3 receptor in the primary afferent neuron.

    Science.gov (United States)

    Oliveira-Fusaro, Maria Cláudia Gonçalves; Zanoni, Cristiane Isabel Silva; Dos Santos, Gilson Gonçalves; Manzo, Luis Paulo; Araldi, Dionéia; Bonet, Ivan José Magayewski; Tambeli, Cláudia Herrera; Dias, Elayne Vieira; Parada, Carlos Amilcar

    2017-03-05

    Cannabinoid system is a potential target for pain control. Cannabinoid receptor 1 (CB1) activation play a role in the analgesic effect of cannabinoids once it is expressed in primary afferent neurons. This study investigates whether the anti-hyperalgesic effect of CB1 receptor activation involves P2X3 receptor in primary afferent neurons. Mechanical hyperalgesia was evaluated by electronic von Frey test. Cannabinoid effect was evaluated using anandamide or ACEA, a non-selective or a selective CB1 receptor agonists, respectively; AM251, a CB1 receptor antagonist, and antisense ODN for CB1 receptor. Calcium imaging assay was performed to evaluated α,β-meATP-responsive cultured DRG neurons pretreated with ACEA. Anandamide or ACEA administered in peripheral tissue reduced the carrageenan-induced mechanical hyperalgesia. The reduction in the carrageenan-induced hyperalgesia induced by ACEA was completely reversed by administration of AM251 as well as by the intrathecal treatment with antisense ODN for CB1 receptor. Also, ACEA reduced the mechanical hyperalgesia induced by bradykinin and by α,β-meATP, a P2X3 receptor non-selective agonist, but not by tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β) and chemokine-induced chemoattractant-1 (CINC-1). Finally, CB1 receptors are co-localized with P2X3 receptors in DRG small-diameter neurons and the treatment with ACEA reduced the number of α,β-meATP-responsive cultured DRG neurons. Our data suggest that the analgesic effect of CB1 receptor activation is mediated by a negative modulation of the P2X3 receptor in the primary afferent neurons.

  2. GABAB antagonists

    DEFF Research Database (Denmark)

    Frydenvang, Karla Andrea; Hansen, J J; Krogsgaard-Larsen, P

    1994-01-01

    Phaclofen, which is the phosphonic acid analogue of the GABAB agonist (RS)-3-(4-chlorophenyl)-4-aminobutyric acid (baclofen), is a GABAB antagonist. As part of our studies on the structural requirements for activation and blockade of GABAB receptors, we have resolved phaclofen using chiral chroma...

  3. Non-Selective Lexical Access in Different-Script Bilinguals

    Science.gov (United States)

    Moon, Jihye; Jiang, Nan

    2012-01-01

    Lexical access in bilinguals is known to be largely non-selective. However, most studies in this area have involved bilinguals whose two languages share the same script. This study aimed to examine bilingual lexical access among bilinguals whose two languages have distinct scripts. Korean-English bilinguals were tested in a phoneme monitoring task…

  4. AFM imaging reveals the assembly of a P2X receptor complex containing P2X2, P2X4 and P2X6 subunits

    OpenAIRE

    2012-01-01

    Seven P2X purinergic receptor subunits have been identified: P2X1-P2X7. All except P2X6 assemble as homotrimers, and six heteromeric receptors (P2X1/2, P2X1/4, P2X1/5, P2X2/3, P2X2/6 and P2X4/6) have been described. In addition, P2X4 homomers associate with P2X2 or P2X7 homomers as dimers of trimers. The various P2X receptors show individual functional properties, suggesting distinct physiological roles. The overlapping expression of P2X2, P2X4 and P2X6 subunits has been shown in different ce...

  5. P2X7 receptors in cerebral ischemia

    Institute of Scientific and Technical Information of China (English)

    Hui-Yu Bai; Ai-Ping Li

    2013-01-01

    Cerebral ischemia is one of the most common diseases resulting in death and disability in aged people.It leads immediately to rapid energy failure,ATP depletion,and ionic imbalance,which increase extracellular ATP levels and accordingly activate P2X7 receptors.These receptors are ATP-gated cation channels and widely distributed in nerve cells,especially in the immunocompetent cells of the brain.Currently,interest in the roles of P2X7 receptors in ischemic brain injury is growing.In this review,we discuss recent research progress on the actions of P2X7 receptors,their possible mechanisms in cerebral ischemia,and the potential therapeutic value of P2X7 receptor antagonists which may provide a new target both for clinical and for research purposes.

  6. Platelet P2 receptors: from curiosity to clinical targets.

    Science.gov (United States)

    Cusack, N J; Hourani, S M

    2000-07-01

    Adenosine 5'-diphosphate (ADP) is a paracrine mediator that activates human blood platelets, causing them to become adhesive and thereby contributing to their role in hemostasis. The actions of ADP were initially thought to be mediated by a unique ADP receptor termed P2(T) found only on platelets and antagonized by ATP, but it appears that at least two P2Y receptor subtypes are involved, a P2Y(1) receptor linked in some way to control of intracellular-free calcium levels and another P2Y receptor linked via an inhibitory G protein to adenylate cyclase. In addition, the presence of excitatory P2X(1) receptors that mediate the influx of monovalent and divalent cations in response to both ADP and ATP has been demonstrated. The precise contribution that each of these P2 receptors make to the overall phenomena associated with platelet aggregation, adhesion and hemostasis is yet to be defined. Antithrombotic agents that interfere with the actions of ADP are marketed, and P2 receptor antagonists are entering clinical trials for acute treatments of thrombosis. This review seeks to summarize the present state of knowledge of platelet P2 receptor pharmacology and therapeutics.

  7. P2X7 receptor in epilepsy; role in pathophysiology and potential targeting for seizure control.

    OpenAIRE

    Engel, Tobias; Jimenez-Pacheco, Alba; Miras-Portugal, Maria Teresa; Diaz-Hernandez, Miguel; Henshall, David C.

    2012-01-01

    The P2X7 receptor is an ATP-gated non-selective cation-permeable ionotropic receptor selectively expressed in neurons and glia in the brain. Activation of the P2X7 receptor has been found to modulate neuronal excitability in the hippocampus and it has also been linked to microglia activation and neuroinflammatory responses. Accordingly, interest developed on the P2X7 receptor in disorders of the nervous system, including epilepsy. Studies show that expression of the P2X7 receptor is elevated ...

  8. Adventures in the pharmacological analysis of P2 receptors.

    Science.gov (United States)

    Fagura, M S; Jarvis, G E; Dougall, I G; Leff, P

    2000-07-01

    The pharmacological classification of P2 receptors owes its origin to the pioneering efforts of Geoff Burnstock and those who followed him, research that was conducted primarily in physiological experimental systems. Over recent years, the techniques of molecular biology have been increasingly applied in the study of P2 receptors while, at the same time, advances in their pharmacological analysis have been limited by a lack of potent and selective agonist or antagonist ligands. This has resulted in a classification scheme which is largely structural in nature, with relatively little contribution from pharmacology. Our endeavours in this area have been directed towards the discovery of ligands with which the pharmacological analysis and definition of P2 receptors could be advanced, the ultimate goal being the design of therapeutic agents. This article will describe some of our experiences in this challenging but rewarding area.

  9. Action of natural products on p2 receptors: a reinvented era for drug discovery.

    Science.gov (United States)

    Faria, Robson; Ferreira, Leonardo; Bezerra, Rômulo; Frutuoso, Valber; Alves, Luiz

    2012-11-01

    Natural products contribute significantly to available drug therapies and have been a rich source for scientific investigation. In general, due to their low cost and traditional use in some cultures, they are an object of growing interest as alternatives to synthetic drugs. With several diseases such as cancer, and inflammatory and neuropathic diseases having been linked to the participation of purinergic (P2) receptors, there has been a flurry of investigations on ligands within natural products. Thirty-four different sources of these compounds have been found so far, that have shown either agonistic or antagonistic effects on P2 receptors. Of those, nine different plant sources demonstrated effects on P2X2, P2X3, P2X7, and possibly P2Y12 receptor subtypes. Microorganisms, which represent the largest group, with 26 different sources, showed effects on both receptor subtypes, ranging from P2X1 to P2X4 and P2X7, and P2Y1, P2Y2, P2Y4, and P2Y6. In addition, there were seventeen animal sources that affected P2X7 and P2Y1 and P2Y12 receptors. Natural products have provided some fascinating new mechanisms and sources to better understand the P2 receptor antagonism. Moreover, current investigations should clarify further pharmacological mechanisms in order to consider these products as potential new medicines.

  10. Action of Natural Products on P2 Receptors: A Reinvented Era for Drug Discovery

    Directory of Open Access Journals (Sweden)

    Luiz Alves

    2012-11-01

    Full Text Available Natural products contribute significantly to available drug therapies and have been a rich source for scientific investigation. In general, due to their low cost and traditional use in some cultures, they are an object of growing interest as alternatives to synthetic drugs. With several diseases such as cancer, and inflammatory and neuropathic diseases having been linked to the participation of purinergic (P2 receptors, there has been a flurry of investigations on ligands within natural products. Thirty-four different sources of these compounds have been found so far, that have shown either agonistic or antagonistic effects on P2 receptors. Of those, nine different plant sources demonstrated effects on P2X2, P2X3, P2X7, and possibly P2Y12 receptor subtypes. Microorganisms, which represent the largest group, with 26 different sources, showed effects on both receptor subtypes, ranging from P2X1 to P2X4 and P2X7, and P2Y1, P2Y2, P2Y4, and P2Y6. In addition, there were seventeen animal sources that affected P2X7 and P2Y1 and P2Y12 receptors. Natural products have provided some fascinating new mechanisms and sources to better understand the P2 receptor antagonism. Moreover, current investigations should clarify further pharmacological mechanisms in order to consider these products as potential new medicines.

  11. ACTH antagonists

    Directory of Open Access Journals (Sweden)

    Adrian John Clark

    2016-08-01

    Full Text Available ACTH acts via a highly selective receptor that is a member of the melanocortin receptor subfamily of type 1 G protein-coupled receptors. The ACTH receptor, also known as the melanocortin 2 receptor (MC2R is unusual in that it is absolutely dependent on a small accessory protein, melanocortin receptor accessory protein (MRAP for cell surface expression and function. ACTH is the only known naturally occurring agonist for this receptor. This lack of redundancy and high degree of ligand specificity suggests that antagonism of this receptor could provide a useful therapeutic aid and a potential investigational tool. Clinical situations in which this could be useful include (1 Cushing’s disease and ectopic ACTH syndrome – especially whilst preparing for definitive treatment of a causative tumour, or in refractory cases, or (2 congenital adrenal hyperplasia – as an adjunct to glucocorticoid replacement. A case for antagonism in other clinical situations in which there is ACTH excess can also be made. In this article we will explore the scientific and clinical case for an ACTH antagonist, and will review the evidence for existing and recently described peptides and modified peptides in this role.

  12. CAY10593 inhibits the human P2X7 receptor independently of phospholipase D1 stimulation

    OpenAIRE

    Pupovac, A.; Stokes, L; Sluyter, R.

    2013-01-01

    The P2X7 receptor is a trimeric ATP-gated cation channel important in health and disease. We have observed that the specific phospholipase D (PLD)1 antagonist, CAY10593 impairs P2X7-induced shedding of the ‘low affinity’ IgE receptor, CD23. The current study investigated the mode of action of this compound on P2X7 activation. Measurements of ATP-induced ethidium+ uptake revealed that CAY10593 impaired P2X7-induced pore formation in human RPMI 8226 B cells, P2X7-transfected HEK-293 cells and p...

  13. P2X7R activation drives distinct IL-1 responses in dendritic cells compared to macrophages

    OpenAIRE

    Englezou, Pavlos C.; Rothwell, Simon W.; Ainscough, Joseph S.; Brough, David; Landsiedel, Robert; Verkhratsky, Alexei; Kimber, Ian; Dearman, Rebecca J

    2015-01-01

    The P2X7R is a functionally distinct member of the P2X family of non-selective cation channels associated with rapid activation of the inflammasome complex and signalling interleukin (IL)-1β release in macrophages. The main focus of this investigation was to compare P2X7R-driven IL-1 production by primary murine bone marrow derived dendritic cells (BMDC) and macrophages (BMM). P2X7R expression in murine BMDC and BMM at both transcriptional (P2X7A variant) and protein levels was demonstrated....

  14. Ibudilast: a non-selective phosphodiesterase inhibitor in brain disorders

    Directory of Open Access Journals (Sweden)

    Joanna Schwenkgrub

    2017-03-01

    Full Text Available Ibudilast (IBD is a non-selective (3, 4, 10, 11 phosphodiesterase (PDE inhibitor, used mainly as a bronchodilator for the treatment of bronchial asthma. PDE play a central role in cellular function (e.g. differentiation, synaptic plasticity and inflammatory response by metabolizing cyclic nucleotides. The results from preclinical and clinical studies indicate that IBD has a broader range of action through suppression of pro-inflammatory cytokines (IL-6, IL-1β, TNF-α, toll-like receptor 4 blockade (TLR-4, inhibition of a macrophage migration inhibitory factor (MIF, up-regulation the anti-inflammatory cytokine (IL-10, and promotion of neurotrophic factors (GDNF, NGF, NT-4. Recent data indicate that the efficacy of IBD appears to be independent from PDE inhibition activity and rather linked to glial activity attenuation. Additional advantages of IBD, such as crossing the blood–brain barrier, good tolerance and activity by oral administration, makes it a promising therapeutic candidate for treating neuroinflammatory conditions, where the currently available treatment remains unsatisfying due to poor tolerability and/or sub-optimal efficacy. IBD has no direct receptor affinity with exemption of some undefined effect on adenosine receptors that makes the drug devoid of its receptors-mediated adverse effects. Current article provides an overview of the pharmacology of IBD with a focus on preclinical and clinical data supporting its potential neuroprotective benefits for neurological conditions, including multiple sclerosis, neuropathic pain, medication overuse headache, stroke, opioid, alcohol and methamphetamine abuse.

  15. P2X and P2Y Receptors—Role in the Pathophysiology of the Nervous System

    Directory of Open Access Journals (Sweden)

    Kamila Puchałowicz

    2014-12-01

    Full Text Available Purinergic signalling plays a crucial role in proper functioning of the nervous system. Mechanisms depending on extracellular nucleotides and their P2 receptors also underlie a number of nervous system dysfunctions. This review aims to present the role of purinergic signalling, with particular focus devoted to role of P2 family receptors, in epilepsy, depression, neuropathic pain, nervous system neoplasms, such as glioma and neuroblastoma, neurodegenerative diseases like Parkinson’s disease, Alzheimer’s disease and multiple sclerosis. The above-mentioned conditions are associated with changes in expression of extracellular ectonucleotidases, P2X and P2Y receptors in neurons and glial cells, as well as releasing considerable amounts of nucleotides from activated or damaged nervous tissue cells into the extracellular space, which contributes to disturbance in purinergic signalling. The numerous studies indicate a potential possibility of using synthetic agonists/antagonists of P2 receptors in treatment of selected nervous system diseases. This is of particular significance, since numerous available agents reveal a low effectiveness and often produce side effects.

  16. In search of selective P2 receptor ligands: interaction of dihydropyridine derivatives at recombinant rat P2X(2) receptors.

    Science.gov (United States)

    Jacobson, K A; Kim, Y C; King, B F

    2000-07-01

    1,4-Dihydropyridines are regarded as privileged structures for drug design, i.e. they tend to bind to a wide variety of receptor sites. We have shown that upon appropriate manipulation of the substituent groups on a 1,4-dihydropyridine template, high affinity and selectivity for the A(3) subtype of adenosine receptors ('P1 receptors') may be attained. In the present study we have begun to extend this approach to P2 receptors which are activated by ATP and other nucleotides. Nicardipine, a representative dihydropyridine, used otherwise as an L-type calcium channel blocker, was shown to be an antagonist at recombinant rat P2X(2) (IC(50)=25 microM) and P2X(4) (IC(50) approximately 220 microM) receptors expressed in Xenopus oocytes. Thus, this class of compounds represents a suitable lead for enhancement of affinity through chemical synthesis. In an attempt to modify the 1,4-dihydropyridine structure with a predicted P2 receptor recognition moiety, we have replaced one of the ester groups with a negatively charged phosphonate group. Several 4-phenyl-5-phosphonato-1,4-dihydropyridine derivatives, MRS 2154 (2, 6-dimethyl), MRS 2155 (6-methyl-2-phenyl), and MRS 2156 (2-methyl-6-phenyl), were synthesized through three component condensation reactions. These derivatives were not pure antagonists of the effects of ATP at P2X(2) receptors, rather were either inactive (MRS 2156) or potentiated the effects of ATP in a concentration-dependent manner (MRS 2154 in the 0.3-10 microM range and MRS 2155 at >1 microM). Antagonism of the effects of ATP at P2X(2) receptor superimposed on the potentiation was also observed at >10 microM (MRS 2154) or 0.3-1 microM (MRS 2155). Thus, while a conventional dihydropyridine, nicardipine, was found to antagonize rat P2X(2) receptors ninefold more potently than P2X(4) receptors, the effects of novel, anionic 5-phosphonate analogues at the receptor were more complex.

  17. In search of selective P2 receptor ligands: interaction of dihydropyridine derivatives at recombinant rat P2X2 receptors

    Science.gov (United States)

    Jacobson, Kenneth A.; Kim, Yong-Chul; King, Brian F.

    2012-01-01

    1,4-Dihydropyridines are regarded as privileged structures for drug design, i.e. they tend to bind to a wide variety of receptor sites. We have shown that upon appropriate manipulation of the substituent groups on a 1,4-dihydropyridine template, high affinity and selectivity for the A3 subtype of adenosine receptors (‘P1 receptors’) may be attained. In the present study we have begun to extend this approach to P2 receptors which are activated by ATP and other nucleotides. Nicardipine, a representative dihydropyridine, used otherwise as an L-type calcium channel blocker, was shown to be an antagonist at recombinant rat P2X2 (IC50 = 25 μM) and P2X4 (IC50 ~ 220 μM) receptors expressed in Xenopus oocytes. Thus, this class of compounds represents a suitable lead for enhancement of affinity through chemical synthesis. In an attempt to modify the 1,4-dihydropyridine structure with a predicted P2 receptor recognition moiety, we have replaced one of the ester groups with a negatively charged phosphonate group. Several 4-phenyl-5-phosphonato-1,4-dihydropyridine derivatives, MRS 2154 (2,6-dimethyl), MRS 2155 (6-methyl-2-phenyl), and MRS 2156 (2-methyl-6-phenyl), were synthesized through three component condensation reactions. These derivatives were not pure antagonists of the effects of ATP at P2X2 receptors, rather were either inactive (MRS 2156) or potentiated the effects of ATP in a concentration-dependent manner (MRS 2154 in the 0.3–10 μM range and MRS 2155 at >1 μM). Antagonism of the effects of ATP at P2X2 receptor superimposed on the potentiation was also observed at >10 μM (MRS 2154) or 0.3–1 μM (MRS 2155). Thus, while a conventional dihydropyridine, nicardipine, was found to antagonize rat P2X2 receptors ninefold more potently than P2X4 receptors, the effects of novel, anionic 5-phosphonate analogues at the receptor were more complex. PMID:10869714

  18. P2X7 receptors mediate ischemic damage to oligodendrocytes.

    Science.gov (United States)

    Domercq, Maria; Perez-Samartin, Alberto; Aparicio, David; Alberdi, Elena; Pampliega, Olatz; Matute, Carlos

    2010-04-15

    Brain ischemia leading to stroke is a major cause of disability in developed countries. Therapeutic strategies have most commonly focused on protecting neurons from ischemic damage. However, ischemic damage to white matter causes oligodendrocyte death, myelin disruption, and axon dysfunction, and it is partially mediated by glutamate excitotoxicity. We have previously demonstrated that oligodendrocytes express ionotropic purinergic receptors. The objective of this study was to investigate the role of purinergic signaling in white matter ischemia. We show that, in addition to glutamate, enhanced ATP signaling during ischemia is also deleterious to oligodendrocytes and myelin, and impairs white matter function. Thus, ischemic oligodendrocytes in culture display an inward current and cytosolic Ca(2+) overload, which is partially mediated by P2X7 receptors. Indeed, oligodendrocytes release ATP after oxygen and glucose deprivation through the opening of pannexin hemichannels. Consistently, ischemia-induced mitochondrial depolarization as well as oxidative stress culminating in cell death are partially reversed by P2X7 receptor antagonists, by the ATP degrading enzyme apyrase and by blockers of pannexin hemichannels. In turn, ischemic damage in isolated optic nerves, which share the properties of brain white matter, is greatly attenuated by all these drugs. Ultrastructural analysis and electrophysiological recordings demonstrated that P2X7 antagonists prevent ischemic damage to oligodendrocytes and myelin, and improved action potential recovery after ischemia. These data indicate that ATP released during ischemia and the subsequent activation of P2X7 receptor is critical to white matter demise during stroke and point to this receptor type as a therapeutic target to limit tissue damage in cerebrovascular diseases.

  19. Effect of P2X4 and P2X7 receptor antagonism on the pressure diuresis relationship in rats

    Directory of Open Access Journals (Sweden)

    Robert I Menzies

    2013-10-01

    Full Text Available Reduced glomerular filtration, hypertension and renal microvascular injury are hallmarks of chronic kidney disease, which has a global prevalence of ~10%. We have shown previously shown that the Fischer (F344 rat has lower GFR than the Lewis rat, and is more susceptible to renal injury induced by hypertension. In the early stages this injury is limited to the pre-glomerular vasculature. We hypothesized that poor renal hemodynamic function and vulnerability to vascular injury are causally linked and genetically determined. In the present study, normotensive F344 rats had a blunted pressure diuresis relationship, compared with Lewis rats. A kidney microarray was the interrogated using the Endeavour enrichment tool to rank candidate genes for impaired blood pressure control. Two novel candidate genes, P2rx7 and P2rx4, were identified, having a 7- and 3- fold increased expression in F344 rats. Immunohistochemistry localized P2X4 and P2X7 receptor expression to the endothelium of the pre-glomerular vasculature. Expression of both receptors was also found in the renal tubule; however there was no difference in expression profile between strains. Brilliant Blue G (BBG, a relatively selective P2X7 antagonist suitable for use in vivo, was administered to both rat strains. In Lewis rats, BBG had no effect on blood pressure, but increased renal vascular resistance, consistent with inhibition of some basal vasodilatory tone. In F344 rats BBG caused a significant reduction in blood pressure and a decrease in renal vascular resistance, suggesting that P2X7 receptor activation may enhance vasoconstrictor tone in this rat strain. BBG also caused reduced the pressure diuresis threshold in F344 rats, but did not alter its slope. These preliminary findings suggest a physiological and potential pathophysiological role for P2X7 in controlling renal and/or systemic vascular function, which could in turn affect susceptibility to hypertension-related kidney damage.

  20. Non-selective beta-adrenergic blockade prevents reduction of the cerebral metabolic ratio during exhaustive exercise in humans

    DEFF Research Database (Denmark)

    Larsen, T.S.; Rasmussen, P.; Overgaard, M.

    2008-01-01

    of a non-selective beta-adrenergic (beta(1) + beta(2)) receptor antagonist (propranolol) reduced heart rate (69 +/- 8 to 58 +/- 6 beats min(-1)) and exercise capacity (239 +/- 42 to 209 +/- 31 W; P exercise with propranolol, the increase in a......Intense exercise decreases the cerebral metabolic ratio of oxygen to carbohydrates [O(2)/(glucose + (1/2)lactate)], but whether this ratio is influenced by adrenergic stimulation is not known. In eight males, incremental cycle ergometry increased arterial lactate to 15.3 +/- 4.2 mm (mean +/- s.......d.) and the arterial-jugular venous (a-v) difference from -0.02 +/- 0.03 mm at rest to 1.0 +/- 0.5 mm (P increased from 0.7 +/- 0.3 to 0.9 +/- 0.1 mm (P

  1. Towards P2P XML Database Technology

    NARCIS (Netherlands)

    Y. Zhang (Ying)

    2007-01-01

    textabstractTo ease the development of data-intensive P2P applications, we envision a P2P XML Database Management System (P2P XDBMS) that acts as a database middle-ware, providing a uniform database abstraction on top of a dynamic set of distributed data sources. In this PhD work, we research which

  2. Emerging key roles for P2X receptors in the kidney

    Directory of Open Access Journals (Sweden)

    Scott S Wildman

    2013-09-01

    Full Text Available P2X ionotropic non-selective cation channels are expressed throughout the kidney and are activated in a paracrine or autocrine manner following the binding of extracellular ATP and related extracellular nucleotides. Whilst there is a wealth of literature describing a regulatory role of P2 receptors (P2R in the kidney, there are significantly less data on the regulatory role of P2X receptors (P2XR compared with that described for metabotropic P2Y. Much of the historical literature describing a role for P2XR in the kidney has focused heavily on the role of P2X1R in the autoregulation of renal blood flow. More recently however, there has been a plethora of manuscripts providing compelling evidence for additional roles for P2XR in both kidney health and disease. This review summarizes the current evidence for the involvement of P2XR in the regulation of renal tubular and vascular function, and highlights the novel data describing their putative roles in regulating physiological and pathophysiological processes in the kidney.

  3. Heteromeric assembly of P2X subunits

    Directory of Open Access Journals (Sweden)

    Anika eSaul

    2013-12-01

    Full Text Available Transcripts and/or proteins of P2X receptor (P2XR subunits have been found in virtually all mammalian tissues. Generally more than one of the seven known P2X subunits have been identified in a given cell type. Six of the seven cloned P2X subunits can efficiently form functional homotrimeric ion channels in recombinant expression systems. This is in contrast to other ligand-gated ion channel families, such as the Cys-loop or glutamate receptors, where homomeric assemblies seem to represent the exception rather than the rule. P2XR mediated responses recorded from native tissues rarely match exactly the biophysical and pharmacological properties of heterologously expressed homomeric P2XRs. Heterotrimerization of P2X subunits is likely to account for this observed diversity. While the existence of heterotrimeric P2X2/3Rs and their role in physiological processes is well established, the composition of most other P2XR heteromers and/or the interplay between distinct trimeric receptor complexes in native tissues is not clear. After a description of P2XR assembly and the structure of the intersubunit ATP-binding site, this review summarizes the distribution of P2XR subunits in selected mammalian cell types and the biochemically and/or functionally characterized heteromeric P2XRs that have been observed upon heterologous co-expression of P2XR subunits. We further provide examples where the postulated heteromeric P2XRs have been suggested to occur in native tissues and an overview of the currently available pharmacological tools that have been used to discriminate between homo- and heteromeric P2XRs

  4. The role of P2X7 receptors in a rodent PCP-induced schizophrenia model.

    Science.gov (United States)

    Koványi, Bence; Csölle, Cecilia; Calovi, Stefano; Hanuska, Adrienn; Kató, Erzsébet; Köles, László; Bhattacharya, Anindya; Haller, József; Sperlágh, Beáta

    2016-11-08

    P2X7 receptors (P2X7Rs) are ligand-gated ion channels sensitive to extracellular ATP. Here we examined for the first time the role of P2X7R in an animal model of schizophrenia. Using the PCP induced schizophrenia model we show that both genetic deletion and pharmacological inhibition of P2X7Rs alleviate schizophrenia-like behavioral alterations. In P2rx7+/+ mice, PCP induced hyperlocomotion, stereotype behavior, ataxia and social withdrawal. In P2X7 receptor deficient mice (P2rx7-/-), the social interactions were increased, whereas the PCP induced hyperlocomotion and stereotype behavior were alleviated. The selective P2X7 receptor antagonist JNJ-47965567 partly replicated the effect of gene deficiency on PCP-induced behavioral changes and counteracted PCP-induced social withdrawal. We also show that PCP treatment upregulates and increases the functional responsiveness of P2X7Rs in the prefrontal cortex of young adult animals. The amplitude of NMDA evoked currents recorded from layer V pyramidal neurons of cortical slices were slightly decreased by both genetic deletion of P2rx7 and by JNJ-47965567. PCP induced alterations in mRNA expression encoding schizophrenia-related genes, such as NR2A, NR2B, neuregulin 1, NR1 and GABA α1 subunit were absent in the PFC of young adult P2rx7-/- animals. Our findings point to P2X7R as a potential therapeutic target in schizophrenia.

  5. Purinergic signaling in the cerebellum: Bergmann glial cells express functional ionotropic P2X7 receptors.

    Science.gov (United States)

    Habbas, Samia; Ango, Fabrice; Daniel, Hervé; Galante, Micaela

    2011-12-01

    Astrocytes constitute active networks of intercommunicating cells that support the metabolism and the development of neurons and affect synaptic functions via multiple pathways. ATP is one of the major neurotransmitters mediating signaling between neurons and astrocytes. Potentially acting through both purinergic metabotropic P2Y receptors (P2YRs) and ionotropic P2X receptors (P2XRs), up until now ATP has only been shown to activate P2YRs in Bergmann cells, the radial glia of the cerebellar cortex that envelopes Purkinje cell afferent synapses. In this study, using multiple experimental approaches in acute cerebellar slices we demonstrate the existence of functional P2XRs on Bergmann cells. In particular, we show here that Bergmann cells express uniquely P2X7R subtypes: (i) immunohistochemical analysis revealed the presence of P2X7Rs on Bergmann cell processes, (ii) in whole cell recordings P2XR pharmacological agonists induced depolarizing currents that were blocked by specific antagonists of P2X7Rs, and could not be elicited in slices from P2X₇R-deficient mice and finally, (iii) calcium imaging experiments revealed two distinct calcium signals triggered by application of exogenous ATP: a transient signal deriving from release of calcium from intracellular stores, and a persistent one following activation of P2X7Rs. Our data thus reveal a new pathway by which extracellular ATP may affect glial cell function, thus broadening our knowledge on purinergic signaling in the cerebellum.

  6. Panasonic E系列P2

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    从今年五月份开始,Panasonic三款新的E系列P2卡将开始上市,分别是16GB(型号AJ—P2E016X)、32GB(型号AJ—P2E032X)和164GB(型号AJ—P2E064X)。P2是公认业界领先的固态记录解决方案。P2卡是高度可靠的视频、音频和数据记录介质,特别是在严酷环境下,包括极端的温度范围、冲击和振动,

  7. P2X receptors in epithelia

    DEFF Research Database (Denmark)

    Leipziger, Jens Georg

    2015-01-01

    pathways that inhibit epithelial absorption are currently not well understood. Epithelial P2X7 receptors show pronounced up-regulation during varies diseased states highlighting a role of purinergic signaling in epithelial pathophysiology. Importantly, functional effects of epithelial P2X receptors cover......P2X receptors are ubiquitously expressed in all epithelial tissues but their functional roles are less well studied. Here we review the current state of knowledge by focusing on functional effects of P2X receptor in secretory and in absorptive tissues. In glandular tissue like the parotid gland...... basolateral P2X receptors stimulate ion secretion via an increase of [Ca2+]i. In absorptive epithelia like the renal tubule P2X receptor stimulation mediates the inhibition of NaCl, Mg2+ and water transport in the thick ascending limb and the distal convoluted tubule, respectively. The underlying signaling...

  8. P2P overlay over Simctl

    OpenAIRE

    Sicart López, Gerard Carles

    2016-01-01

    This project intends to find and implement a p2p overlay over the simctl platform. Simctl is used both for teaching and research in the network engineering department. P2P systems became an interesting area since early 2000. Researchers conducted a large amount of research in some challenging areas and, to check their experiments, several implementations and simulators were created. Over time, Internet has evolved and P2P has been widely used for file sharing, but the main structured P2P o...

  9. P2X7 receptors regulate engulfing activity of non-stimulated resting astrocytes.

    Science.gov (United States)

    Yamamoto, Mina; Kamatsuka, Yosuke; Ohishi, Akihiro; Nishida, Kentaro; Nagasawa, Kazuki

    2013-09-13

    We previously demonstrated that P2X7 receptors (P2X7Rs) expressed by cultured mouse astrocytes were activated without any exogenous stimuli, but its roles in non-stimulated resting astrocytes remained unknown. It has been reported that astrocytes exhibit engulfing activity, and that the basal activity of P2X7Rs regulates the phagocytic activity of macrophages. In this study, therefore, we investigated whether P2X7Rs regulate the engulfing activity of mouse astrocytes. Uptake of non-opsonized beads by resting astrocytes derived from ddY-mouse cortex time-dependently increased, and the uptaken beads were detected in the intracellular space. The bead uptake was inhibited by cytochalasin D (CytD), an F-actin polymerization inhibitor, and agonists and antagonists of P2X7Rs apparently decreased the uptake. Spontaneous YO-PRO-1 uptake by ddY-mouse astrocytes was reduced by the agonists and antagonists of P2X7Rs, but not by CytD. Down-regulation of P2X7Rs using siRNA decreased the bead uptake by ddY-mouse astrocytes. In addition, compared to in the case of ddY-mouse astrocytes, SJL-mouse astrocytes exhibited higher YO-PRO-1 uptake activity, and their bead uptake was significantly greater. These findings suggest that resting astrocytes exhibit engulfing activity and that the activity is regulated, at least in part, by their P2X7Rs.

  10. The effect of purinergic P2 receptor blockade on skeletal muscle exercise hyperemia in miniature swine

    DEFF Research Database (Denmark)

    Mortensen, Stefan; McAllister, R M; Yang, H T;

    2014-01-01

    -microsphere technique and systemic hemodynamics before and after arterial infusion of the P2 receptor antagonist reactive blue 2 during treadmill exercise (5.2 km/h, ~60 % VO2max) and arterial ATP infusion in female Yucatan miniature swine (~29 kg). RESULTS: Mean blood flow during exercise from the 16 sampled skeletal...

  11. Basolateral P2X receptors mediate inhibition of NaCl transport in mouse medullary thick ascending limb (mTAL)

    DEFF Research Database (Denmark)

    Marques, Rita D; de Bruijn, Pauline I.A.; Sørensen, Mads Vaarby

    2012-01-01

    receptor antagonist suramin blocked the effect. P2Y receptors were found not to be involved in this effect. The P2X receptor agonist 2MeSATP mimicked the ATP effect and the P2X receptor antagonist oATP blocked it. In P2X(7)(-/-) mice the ATP effect remained unaltered. In contrast, in P2X(4)(-/-) mice......Extracellular nucleotides regulate epithelial transport via luminal and basolateral P2 receptors. Renal epithelia express multiple P2 receptors, which mediate significant inhibition of solute absorption. Recently, we identified several P2 receptors in the medullary thick ascending limb (m......TAL) including luminal and basolateral P2Y(2) receptors. In addition, we found evidence for a basolateral P2X receptor. Here we investigate the effect of basolateral ATP on NaCl absorption in isolated, perfused mouse mTALs using the electrical measurement of equivalent short circuit current (I'(sc)). Non...

  12. Antidepressant-like effects of nicotinic acetylcholine receptor antagonists, but not agonists, in the mouse forced swim and mouse tail suspension tests

    DEFF Research Database (Denmark)

    Andreasen T., Jesper; Olsen, G M; Wiborg, O;

    2009-01-01

    AChR subtype/s involved remains unknown. In this study, we systematically compared the effects of non-selective and selective nicotinic agonists and antagonists in two different tests for antidepressant effects in mice: the tail suspension test and the forced swim test. Compounds: nicotine, RJR-2403 (alpha4......beta2-selective agonist), PNU-282987 (alpha7-selective agonist), mecamylamine (non-selective antagonist), dihydro-beta-erythroidine (DHbetaE; alpha4beta2-selective antagonist), methyllycaconitine (MLA; alpha7-selective antagonist) and hexamethonium (non-brain-penetrant non-selective antagonist). All...... compounds were tested in a locomotor activity paradigm to rule out non-specific stimulant effects. The data show that blockade of nAChRs with mecamylamine, or selective antagonism of alpha4beta2 or alpha7 nAChRs with DHbetaE or MLA, respectively, has antidepressant-like effects. These effects were...

  13. Flexible subunit stoichiometry of functional human P2X2/3 heteromeric receptors.

    Science.gov (United States)

    Kowalski, Maria; Hausmann, Ralf; Schmid, Julia; Dopychai, Anke; Stephan, Gabriele; Tang, Yong; Schmalzing, Günther; Illes, Peter; Rubini, Patrizia

    2015-12-01

    The aim of the present work was to clarify whether heterotrimeric P2X2/3 receptors have a fixed subunit stoichiometry consisting of one P2X2 and two P2X3 subunits as previously suggested, or a flexible stoichiometry containing also the inverse subunit composition. For this purpose we transfected HEK293 cells with P2X2 and P2X3 encoding cDNA at the ratios of 1:2 and 4:1, and analysed the biophysical and pharmacological properties of the generated receptors by means of the whole-cell patch-clamp technique. The concentration-response curves for the selective agonist α,β-meATP did not differ from each other under the two transfection ratios. However, co-expression of an inactive P2X2 mutant and the wild type P2X3 subunit and vice versa resulted in characteristic distortions of the α,β-meATP concentration-response relationships, depending on which subunit was expressed in excess, suggesting that HEK293 cells express mixtures of (P2X2)1/(P2X3)2 and (P2X2)2/(P2X3)1 receptors. Whereas the allosteric modulators H+ and Zn2+ failed to discriminate between the two possible heterotrimeric receptor variants, the α,β-meATP-induced responses were blocked more potently by the competitive antagonist A317491, when the P2X2 subunit was expressed in deficit of the P2X3 subunit. Furthermore, blue-native PAGE analysis of P2X2 and P2X3 subunits co-expressed in Xenopus laevis oocytes and HEK293 cells revealed that plasma membrane-bound P2X2/3 receptors appeared in two clearly distinct heterotrimeric complexes: a (P2X2-GFP)2/(P2X3)1 complex and a (P2X2-GFP)1/(P2X3)2 complex. These data strongly indicate that the stoichiometry of the heteromeric P2X2/3 receptor is not fixed, but determined in a permutational manner by the relative availability of P2X2 and P2X3 subunits.

  14. P2 performance measurement tools workbook: Draft

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-06-01

    The underlying purpose of the Department of Energy`s (DOE) Waste Minimization and Pollution Prevention (WMin/P2) Program is compliance with the waste management regulations set forth by the DOE, the federal government, and individual state and local agencies 1. In addition to these regulatory mandates, the increases in waste management costs and public interest in environmental issues have created other drivers to develop and demonstrate an effective WMin/P2 Program. The Waste Minimization Division (EM-334) must have adequate methods to calculate and roll up pollution prevention (P2) progress to meet the WMin/P2 requirements; these requirements support DOE and national objectives and direct funding. This document outlines a system to evaluate DOE`s P2 progress towards the waste reduction requirements. The emphasis of these pollution prevention measurements is to evaluate whether P2 activities are effective, (i.e., has the required amount of waste been reduced as a result of the P2 activities) and to evaluate the cost management of P2 projects. The performance evaluation system presented in this document encompass these aspects: (1) site requirements that apply to all DOE waste generating organizations, (2) a baseline that is not affected by short-term waste generation, and (3) key indicators that can be rolled up across DOE sites and across specific Cognizant Secretarial Officers` (CSO) sites. In a performance-based management system, requirements are the fundamental link between the planning and measurement process. The site requirements are {open_quotes}targets{close_quotes} at the process or activity level. Measuring DOE`s P2 progress toward these requirements provides the necessary feedback to (1) compare performance with the requirements/standards (i.e., whether the reduction requirement of 50% by 1999 is achievable) (2) detect departures from planned levels of performance, and (3) restore performance to the planned levels or achieve new levels of performance.

  15. Modulating P2X7 Receptor Signaling during Rheumatoid Arthritis: New Therapeutic Approaches for Bisphosphonates

    Directory of Open Access Journals (Sweden)

    Alberto Baroja-Mazo

    2012-01-01

    Full Text Available P2X7 receptor-mediated purinergic signaling is a well-known mechanism involved in bone remodeling. The P2X7 receptor has been implicated in the pathophysiology of various bone and cartilage diseases, including rheumatoid arthritis (RA, a widespread and complex chronic inflammatory disorder. The P2X7 receptor induces the release into the synovial fluid of the proinflammatory factors (e.g., interleukin-1β, prostaglandins, and proteases responsible for the clinical symptoms of RA. Thus, the P2X7 receptor is emerging as a novel anti-inflammatory therapeutic target, and various selective P2X7 receptor antagonists are under clinical trials. Extracellular ATP signaling acting through the P2X7 receptor is a complex and dynamic scenario, which varies over the course of inflammation. This signaling is partially modulated by the activity of ectonucleotidases, which degrade extracellular ATP to generate other active molecules such as adenosine or pyrophosphates. Recent evidence suggests differential extracellular metabolism of ATP during the resolution of inflammation to generate pyrophosphates. Extracellular pyrophosphate dampens proinflammatory signaling by promoting alternative macrophage activation. Our paper shows that bisphosphonates are metabolically stable pyrophosphate analogues that are able to mimic the anti-inflammatory function of pyrophosphates. Bisphosphonates are arising per se as promising anti-inflammatory drugs to treat RA, and this therapy could be improved when administrated in combination with P2X7 receptor antagonists.

  16. Characterizing C6+P2-graphic Sequences

    Institute of Scientific and Technical Information of China (English)

    HU Li-li

    2014-01-01

    For a given graph H, a graphic sequence π = (d1, d2, · · · , dn) is said to be potentially H-graphic if π has a realization containing H as a subgraph. In this paper, we characterize the potentially C6 +P2-graphic sequences where C6 +P2 denotes the graph obtained from C6 by adding two adjacent edges to the three pairwise nonadjacent vertices of C6. Moreover, we use the characterization to determine the value ofσ(C6+P2, n).

  17. Evidence for functional P2X4/P2X7 heteromeric receptors.

    Science.gov (United States)

    Guo, Chang; Masin, Marianela; Qureshi, Omar S; Murrell-Lagnado, Ruth D

    2007-12-01

    The cytolytic ionotropic ATP receptor P2X7 has several important roles in immune cell regulation, such as cytokine release, apoptosis, and microbial killing. Although P2X7 receptors are frequently coexpressed with another subtype of P2X receptor, P2X4, they are believed not to form heteromeric assemblies but to function only as homomers. Both receptors play a role in neuropathic pain; therefore, understanding how they coordinate the cellular response to ATP is important for the development of effective pain therapies. Here, we provide biochemical and electrophysiological evidence for an association between P2X4 and P2X7 that increases the diversity of receptor currents mediated via these two subtypes. The heterologously expressed receptors were coimmunoprecipitated from human embryonic kidney (HEK) 293 cells, and the endogenous P2X4 and P2X7 receptors were similarly coimmunoprecipitated from bone marrow-derived macrophages. In HEK293 cells, the fraction of P2X4 receptors biotinylated at the plasma membrane increased 2-fold in the presence of P2X7 although there was no change in overall expression. Coexpression of a dominant-negative P2X4 mutant (C353W) with P2X7, inhibited P2X7 receptor mediated currents by greater than 2-fold, whereas a nonfunctional but non-dominant-negative mutant (S341W) did not. Coexpression of P2X4S341W with P2X7 produced a current that was potentiated by ivermectin and inhibited by 2',3'-O-(2,4,6-trinitrophenyl) adenosine 5-triphosphate (TNP-ATP), whereas expression of P2X7 alone produced a current that was insensitive to both of these compounds at the concentrations used. These results demonstrate a structural and functional interaction between P2X4 and P2X7, which suggests that they associate to form heteromeric receptors.

  18. The ATP Receptors P2X7 and P2X4 Modulate High Glucose and Palmitate-Induced Inflammatory Responses in Endothelial Cells.

    Directory of Open Access Journals (Sweden)

    Ramasri Sathanoori

    Full Text Available Endothelial cells lining the blood vessels are principal players in vascular inflammatory responses. Dysregulation of endothelial cell function caused by hyperglycemia, dyslipidemia, and hyperinsulinemia often result in impaired vasoregulation, oxidative stress, inflammation, and altered barrier function. Various stressors including high glucose stimulate the release of nucleotides thus initiating signaling via purinergic receptors. However, purinergic modulation of inflammatory responses in endothelial cells caused by high glucose and palmitate remains unclear. In the present study, we investigated whether the effect of high glucose and palmitate is mediated by P2X7 and P2X4 and if they play a role in endothelial cell dysfunction. Transcript and protein levels of inflammatory genes as well as reactive oxygen species production, endothelial-leukocyte adhesion, and cell permeability were investigated in human umbilical vein endothelial cells exposed to high glucose and palmitate. We report high glucose and palmitate to increase levels of extracellular ATP, expression of P2X7 and P2X4, and inflammatory markers. Both P2X7 and P2X4 antagonists inhibited high glucose and palmitate-induced interleukin-6 levels with the former having a significant effect on interleukin-8 and cyclooxygenase-2. The effect of the antagonists was confirmed with siRNA knockdown of the receptors. In addition, P2X7 mediated both high glucose and palmitate-induced increase in reactive oxygen species levels and decrease in endothelial nitric oxide synthase. Blocking P2X7 inhibited high glucose and palmitate-induced expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 as well as leukocyte-endothelial cell adhesion. Interestingly, high glucose and palmitate enhanced endothelial cell permeability that was dependent on both P2X7 and P2X4. Furthermore, antagonizing the P2X7 inhibited high glucose and palmitate-mediated activation of p38-mitogen

  19. Role of purinergic P2X4 receptors in regulating striatal dopamine homeostasis and dependent behaviors.

    Science.gov (United States)

    Khoja, Sheraz; Shah, Vivek; Garcia, Damaris; Asatryan, Liana; Jakowec, Michael W; Davies, Daryl L

    2016-10-01

    Purinergic P2X4 receptors (P2X4Rs) belong to the P2X superfamily of ion channels regulated by ATP. We recently demonstrated that P2X4R knockout (KO) mice exhibited deficits in sensorimotor gating, social interaction, and ethanol drinking behavior. Dopamine (DA) dysfunction may underlie these behavioral changes, but there is no direct evidence for P2X4Rs' role in DA neurotransmission. To test this hypothesis, we measured markers of DA function and dependent behaviors in P2X4R KO mice. P2X4R KO mice exhibited altered density of pre-synaptic markers including tyrosine hydroxylase, dopamine transporter; post-synaptic markers including dopamine receptors and phosphorylation of downstream targets including dopamine and cyclic-AMP regulated phosphoprotein of 32 kDa and cyclic-AMP-response element binding protein in different parts of the striatum. Ivermectin, an allosteric modulator of P2X4Rs, significantly affected dopamine and cyclic AMP regulated phosphoprotein of 32 kDa and extracellular regulated kinase1/2 phosphorylation in the striatum. Sensorimotor gating deficits in P2X4R KO mice were rescued by DA antagonists. Using the 6-hydroxydopamine model of DA depletion, P2X4R KO mice exhibited an attenuated levodopa (L-DOPA)-induced motor behavior, whereas ivermectin enhanced this behavior. Collectively, these findings identified an important role for P2X4Rs in maintaining DA homeostasis and illustrate how this association is important for CNS functions including motor control and sensorimotor gating. We propose that P2X4 receptors (P2X4Rs) regulate dopamine (DA) homeostasis and associated behaviors. Pre-synaptic and post-synaptic DA markers were significantly altered in the dorsal and ventral striatum of P2X4R KO mice, implicating altered DA neurotransmission. Sensorimotor gating deficits in P2X4R KO mice were rescued by DA antagonists. Ivermectin (IVM), a positive modulator of P2X4Rs, enhanced levodopa (L-DOPA)-induced motor behavior. These studies highlight potential

  20. The relationship between P2X4 and P2X7: a physiologically important interaction?

    Directory of Open Access Journals (Sweden)

    Eilidh eCraigie

    2013-08-01

    Full Text Available Purinergic signaling within the kidney is becoming an important focus in the study of renal health and disease. The effectors of ATP signaling, the P2Y and P2X receptors, are expressed to varying extents in and along the nephron. There are many studies demonstrating the importance of the P2Y2 receptor on kidney function, and other P2 receptors are now emerging as participants in renal regulation. The P2X4 receptor has been linked to epithelial sodium transport in the nephron and expression levels of the P2X7 receptor are up-regulated in certain pathophysiological states. P2X7 antagonism has been shown to ameliorate rodent models of DOCA salt-induced hypertension and P2X4 null mice are hypertensive. Interestingly, polymorphisms in the genetic loci of P2X4 and P2X7 have been linked to blood pressure variation in human studies. In addition to the increasing evidence linking these two P2X receptors to renal function and health, a number of studies link the two receptors in terms of physical associations between their subunits, demonstrated both in vitro and in vivo. This review will analyze the current literature regarding interactions between P2X4 and P2X7 and assess the potential impact of these with respect to renal function.

  1. P2X7 receptors enhance glutamate release in hippocampal hilar neurons.

    Science.gov (United States)

    Cho, Jin-Hwa; Choi, In-Sun; Jang, Il-Sung

    2010-09-15

    We examined the effect of 2'-3'-O-(4-benzoylbenzoyl)-adenosine-5'-triphosphate (Bz-ATP), a P2X7 receptor agonist, on action potential-independent glutamate release from nerve terminals attached to mechanically isolated immature hilar neurons. Bz-ATP increased spontaneous excitatory postsynaptic current (sEPSC) frequency, and this effect was blocked by Brilliant blue G, a P2X7 receptor antagonist, suggesting that P2X7 receptors mediate the facilitatory action of Bz-ATP on sEPSCs. In most of hilar neurons tested, the Bz-ATP-induced increase in sEPSC frequency was blocked by tetrodotoxin or Cd, suggesting that the activation of P2X7 receptors leads to a presynaptic depolarization. The P2X7 receptor-mediated facilitation of glutamate release would modulate the excitability of hilar neurons, and eventually have a broad impact on the pathophysiological functions mediated by the hippocampus.

  2. Haemolysis induced by α-toxin from Staphylococcus aureus requires P2X receptor activation

    DEFF Research Database (Denmark)

    Skals, Marianne Gerberg; Leipziger, Jens Georg; Prætorius, Helle

    2011-01-01

    receptor activation. We observed that α-toxin-induced haemolysis is completely blocked by the unselective P2 receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid. Moreover, several selective blockers of P2X1 and P2X7 ionotropic receptors abolished haemolysis in murine and equine......Recently, it was documented that α-haemolysin (HlyA) from Escherichia coli uses erythrocyte P2 receptors cause lysis. This finding was surprising as it appeared firmly established that HlyA-dependent pore formation per se is sufficient for full cell lysis. We discovered that HlyA induced...... a sequential process of shrinkage and swelling and that the final haemolysis is completely prevented by blockers of P2X receptors and pannexin channels. This finding has potential clinical relevance as it may offer specific pharmacological interference to ameliorate haemolysis inflicted by pore...

  3. Characterization of P2P Systems

    Science.gov (United States)

    Stutzbach, Daniel; Rejaie, Reza

    The combination of large scale and geographically distributed nature of P2P system has led to their significant impact on the Internet. It is essential to characterize deployed P2P system for at least three reasons: (1) Accurately assessing their impact on the Internet, (2) identifying any performance bottleneck as well as any opportunity for performance improvement, (3) understanding user-driven dynamics in P2P systems. To characterize a P2P system, one needs to accurately capture snapshots of the resulting P2P overlay. This is challenging because the overlay is often large and dynamic. While the overlay is discovered by a crawler, it is changing which leads to a distorted view of the system. Capturing unbiased view of the traffic in the overlay is equally challenging because it is difficult to show that the captured behavior represent the observed behavior by all peers. In this chapter, we describe some of the fundamental problems in empirical characterization of widely deployed P2P systems. We present several examples to illustrate the effect of ad-hoc measurement/data collection on the resulting analysis/characterization. We then present two sampling techniques as a powerful approach to capture unbiased view of peer properties in a scalable fashion.

  4. Detection of P2z/P2x7 Receptors%P2z/P2x7受体检测的研究

    Institute of Scientific and Technical Information of China (English)

    彭黎明; 杨寒朔; 张芹

    2003-01-01

    目的检测白血病细胞的P2z/P2x7受体.方法将T淋巴细胞白血病细胞株(CEM)、急性单核细胞白血病细胞株(THP-1)、M2型白血病细胞株(HL-60)、M3型白血病细胞株(NB4)、巨核细胞病细胞株(Dami/Dam)和伯基特淋巴瘤细胞株(Raji)共六株白血病细胞株制成2×107/ml的细胞悬液,分别加入P2z/P2x7受体的激动剂ATP和/或特异性抑制剂KN-62,测定加入前后细胞内荧光强度变化,同时以P2z/P2x7受体多克隆抗体免疫组化ABC法鉴定P2z/P2x7受体.结果① 0.4 mmol/L的ATP对于THP-1、NB4和HL-60细胞株钙离子通透性有较强的激活作用,其激活率分别为54.91%、39.45%和30.46%;ATP对CEM、Dam和Raji细胞株的激活作用很弱,激活率分别为10.435%、13.215%和2.67%; KN-62对THP-1有很强的抑制作用(抑制率达88.74%),而对NB4和HL-60的抑制作用很弱(抑制率仅为15.81%和12.50%),对Raji细胞株没有抑制作用;②免疫组化ABC法显示各对照细胞株均成阴性,而白血病细胞株均成阳性.结论 THP-1细胞含P2z/P2x7受体,NB4和HL-60含P2受体其它亚型的细胞株,CEM、Raji和Dam细胞株不含P2z/P2x7受体;免疫组化ABC法使用的多克隆抗体与其它蛋白有交叉反应,其结果不具P2z/P2x7受体特异性.

  5. P2X and P2Y receptor signaling in red blood cells.

    Science.gov (United States)

    Sluyter, Ronald

    2015-01-01

    Purinergic signaling involves the activation of cell surface P1 and P2 receptors by extracellular nucleosides and nucleotides such as adenosine and adenosine triphosphate (ATP), respectively. P2 receptors comprise P2X and P2Y receptors, and have well-established roles in leukocyte and platelet biology. Emerging evidence indicates important roles for these receptors in red blood cells. P2 receptor activation stimulates a number of signaling pathways in progenitor red blood cells resulting in microparticle release, reactive oxygen species formation, and apoptosis. Likewise, activation of P2 receptors in mature red blood cells stimulates signaling pathways mediating volume regulation, eicosanoid release, phosphatidylserine exposure, hemolysis, impaired ATP release, and susceptibility or resistance to infection. This review summarizes the distribution of P2 receptors in red blood cells, and outlines the functions of P2 receptor signaling in these cells and its implications in red blood cell biology.

  6. P2X and P2Y receptor signaling in red blood cells

    Directory of Open Access Journals (Sweden)

    Ronald eSluyter

    2015-10-01

    Full Text Available Purinergic signaling involves the activation of cell surface P1 and P2 receptors by extracellular nucleosides and nucleotides such as adenosine and adenosine triphosphate (ATP, respectively. P2 receptors comprise P2X and P2Y receptors, and have well-established roles in leukocyte and platelet biology. Emerging evidence indicates important roles for these receptors in red blood cells. P2 receptor activation stimulates a number of signaling pathways in progenitor red blood cells resulting in microparticle release, reactive oxygen species formation and apoptosis. Likewise, activation of P2 receptors in mature red blood cells stimulates signaling pathways mediating volume regulation, eicosanoid release, phosphatidylserine exposure, hemolysis, impaired ATP release, and susceptibility or resistance to infection. This review summarizes the distribution of P2 receptors in red blood cells, and outlines the functions of P2 receptor signaling in these cells and its implications in red blood cell biology.

  7. Sensitization by extracellular Ca(2+) of rat P2X(5) receptor and its pharmacological properties compared with rat P2X(1).

    Science.gov (United States)

    Wildman, Scott S; Brown, Sean G; Rahman, Mary; Noel, Carole A; Churchill, Linda; Burnstock, Geoffrey; Unwin, Robert J; King, Brian F

    2002-10-01

    The recombinant rat P2X(5) (rP2X(5)) receptor, a poorly understood ATP-gated ion channel, was studied under voltage-clamp conditions and compared with the better understood homomeric rP2X(1) receptor with which it may coexist in vivo. Expressed in defolliculated Xenopus laevis oocytes, rP2X(5) responded to ATP with slowly desensitizing inward currents that, for successive responses, ran down in the presence of extracellular Ca(2+) (1.8 mM). Replacement of Ca(2+) with either Ba(2+) or Mg(2+) prevented rundown, although agonist responses were very small, whereas reintroduction of Ca(2+) for short periods of time ( 2',3'-O-(2,4,6-trinitrophenyl)ATP (TNP-ATP) > suramin > reactive blue 2 (RB-2) > diinosine pentaphosphate (Ip(5)I). In contrast, the potency order at rP2X(1) was TNP-ATP = Ip(5)I > PPADS > suramin = RB-2. Thus, the Ca(2+)-sensitized homomeric rP2X(5) receptor is similar in agonist profile to homomeric rP2X(1)-although it can be distinguished from the latter by GTP agonism, antagonist profile, and the modulatory effects of H(+) and Zn(2+) ions.

  8. Thermoelastic properties of Zn3P2

    DEFF Research Database (Denmark)

    Gerward, Leif; Olsen, J. Staun; Waśkowska, A.

    2011-01-01

    The bulk modulus and thermal expansion of Zn3P2 has been investigated at pressures up to 21GPa and temperatures down to 100K. The experimental zero-pressure bulk modulus is 80.7 ± 1.8GPa, in accordance with the bulk modulus scaling and lattice properties of the related compound Cd3P2. A tetragonal...... to orthorhombic phase transformation occurs above 11GPa with a relative volume change of-7.1%. Values for the thermal expansion coefficient are reported at 293, 200 and 100K....

  9. P2P Techniques for Decentralized Applications

    CERN Document Server

    Pacitti, Esther

    2012-01-01

    As an alternative to traditional client-server systems, Peer-to-Peer (P2P) systems provide major advantages in terms of scalability, autonomy and dynamic behavior of peers, and decentralization of control. Thus, they are well suited for large-scale data sharing in distributed environments. Most of the existing P2P approaches for data sharing rely on either structured networks (e.g., DHTs) for efficient indexing, or unstructured networks for ease of deployment, or some combination. However, these approaches have some limitations, such as lack of freedom for data placement in DHTs, and high late

  10. Allosteric modulation of ATP-gated P2X receptor channels

    Science.gov (United States)

    Coddou, Claudio; Stojilkovic, Stanko S.; Huidobro-Toro, J. Pablo

    2013-01-01

    Seven mammalian purinergic receptor subunits, denoted P2X1 to P2X7, and several spliced forms of these subunits have been cloned. When heterologously expressed, these cDNAs encode ATP-gated non-selective cation channels organized as trimers. All activated receptors produce cell depolarization and promote Ca2+ influx through their pores and indirectly by activating voltage-gated calcium channels. However, the biophysical and pharmacological properties of these receptors differ considerably, and the majority of these subunits are also capable of forming heterotrimers with other members of the P2X receptor family, which confers further different properties. These channels have three ATP binding domains, presumably located between neighboring subunits, and occupancy of at least two binding sites is needed for their activation. In addition to the orthosteric binding sites for ATP, these receptors have additional allosteric sites that modulate the agonist action at receptors, including sites for trace metals, protons, neurosteroids, reactive oxygen species and phosphoinositides. The allosteric regulation of P2X receptors is frequently receptor-specific and could be a useful tool to identify P2X members in native tissues and their roles in signaling. The focus of this review is on common and receptor-specific allosteric modulation of P2X receptors and the molecular base accounting for allosteric binding sites. PMID:21639805

  11. FoxP2 in songbirds

    DEFF Research Database (Denmark)

    Wohlgemuth, Sandra; Adam, Iris; Scharff, Constance

    2014-01-01

    Humans with mutations in the transcription factor FOXP2 display a severe speech disorder. Songbirds are a powerful model system to study FoxP2. Like humans, songbirds communicate via vocalizations that are imitatively learned during critical periods and this learning is influenced by social factors...

  12. P2 receptors in the kidney.

    Science.gov (United States)

    Bailey, M A; Hillman, K A; Unwin, R J

    2000-07-01

    Our understanding of the actions of extracellular ATP in controlling kidney function via stimulation of P2 receptors is still at an early stage. Recently, several groups, including our own, have begun to address this subject: in this brief review, we discuss some of these effects and speculate on likely function of extracellular nucleotides in the kidney.

  13. P2Y6 Receptor Activation Promotes Inflammation and Tissue Remodeling in Pulmonary Fibrosis

    Directory of Open Access Journals (Sweden)

    Tobias Müller

    2017-08-01

    Full Text Available Idiopathic pulmonary fibrosis (IPF is a disease with a poor prognosis and very few available treatment options. The involvement of the purinergic receptor subtypes P2Y2 and P2X7 in fibrotic lung disease has been demonstrated recently. In this study, we investigated the role of P2Y6 receptors in the pathogenesis of IPF in humans and in the animal model of bleomycin-induced lung injury. P2Y6R expression was upregulated in lung structural cells but not in bronchoalveolar lavage (BAL cells derived from IPF patients as well as in animals following bleomycin administration. Furthermore, BAL fluid levels of the P2Y6R agonist uridine-5′-diphosphate were elevated in animals with bleomycin-induced pulmonary fibrosis. Inflammation and fibrosis following bleomycin administration were reduced in P2Y6R-deficient compared to wild-type animals confirming the pathophysiological relevance of P2Y6R subtypes for fibrotic lung diseases. Experiments with bone marrow chimeras revealed the importance of P2Y6R expression on lung structural cells for pulmonary inflammation and fibrosis. Similar effects were obtained when animals were treated with the P2Y6R antagonist MRS2578. In vitro studies demonstrated that proliferation and secretion of the pro-inflammatory/pro-fibrotic cytokine IL-6 by lung fibroblasts are P2Y6R-mediated processes. In summary, our results clearly demonstrate the involvement of P2Y6R subtypes in the pathogenesis of pulmonary fibrosis. Thus, blocking pulmonary P2Y6 receptors might be a new target for the treatment of IPF.

  14. Distribution of P2Y receptor subtypes on haematopoietic cells

    OpenAIRE

    1998-01-01

    RT–PCR-southern hybridization analyses with radiolabelled P2Y receptor cDNAs as probes indicated that the peripheral blood leukocytes and the human umbilical vein endothelial cells express P2Y1, P2Y2, P2Y4 and P2Y6 receptors.Of the haematopoietic cell lines tested, promonocytic U937 cells express P2Y2 and P2Y6, but not P2Y1 or P2Y4; promyelocytic HL-60 cells express the P2Y1, P2Y2 and P2Y6 receptors but not the P2Y4 receptor; K562 cells express P2Y1 but not P2Y2, P2Y4 or P2Y6; and Dami cells ...

  15. Role of P2X7 on steroid synthesis in murine luteal cells

    Directory of Open Access Journals (Sweden)

    Chunping Zhang

    2016-03-01

    Full Text Available The extracellular adenosine triphosphate (ATP regulates different cellular functions through activating purinergic receptors as a signalling molecule or neurotransmitter. P2X7 is highly expressed in murine small luteal cells. In this study, murine luteal cells were cultured in vitro and treated with P2X7 agonists – ATP and 2′(3′-O-(4-benzoyl-benzoyl-adenosine 50-triphosphate (BzATP and with P2X7 antagonist – brilliant blue G (BBG. We found that ATP and BzATP increased the production of progesterone and had no influence on the production of estradiol. BBG reversed the effect of BzATP and ATP. Further studies demonstrated that ATP and BzATP promoted the expression of CYP11A. These results revealed that P2X7 receptor activation is involved in the steroid synthesis in corpus luteum.

  16. Haemolysis induced by α-toxin from Staphylococcus aureus requires P2X receptor activation

    DEFF Research Database (Denmark)

    Skals, Marianne Gerberg; Leipziger, Jens Georg; Prætorius, Helle

    2011-01-01

    -forming bacterial toxins. In this context, it is essential to know whether this is specific to HlyA-induced cell damage or if other bacterial pore-forming toxins involve purinergic signals to orchestrate haemolysis. Here, we investigate if the haemolysis produced by α-toxin from Staphylococcus aureus involves P2...... receptor activation. We observed that α-toxin-induced haemolysis is completely blocked by the unselective P2 receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid. Moreover, several selective blockers of P2X1 and P2X7 ionotropic receptors abolished haemolysis in murine and equine...... erythrocytes. Inhibitors of pannexin channels partially reduced the α-toxin induced lysis. Thus, we conclude that α-toxin, similar to HlyA from E. coli produces cell damage by specific activation of a purinergic signalling cascade. These data indicate that pore-forming toxins in general require purinergic...

  17. A critical look at the function of the P2Y11 receptor

    DEFF Research Database (Denmark)

    Dreisig, Karin; Kornum, Birgitte Rahbek

    2016-01-01

    The P2Y11 receptor is a member of the purinergic receptor family. It has been overlooked, somewhat due to the lack of a P2ry11 gene orthologue in the murine genome, which prevents the generation of knockout mice, which have been so helpful for defining the roles of other P2Y receptors. Furthermore......, some of the studies reported to date have methodological shortcomings, making it difficult to determine the function of P2Y11 with certainty. In this review, we discuss the lack of a murine "P2Y11-like receptor" and highlight the limitations of the currently available methods used to investigate the P2......Y11 receptor. These methods include protein recognition with antibodies that show very little specificity, gene expression studies that completely overlook the existence of a fusion transcript between the adjacent PPAN gene and P2RY11, and agonists/antagonists reported to be specific for the P2Y11...

  18. Mechanism of microglia neuroprotection: Involvement of P2X7, TNFα, and valproic acid.

    Science.gov (United States)

    Masuch, Annette; Shieh, Chu-Hsin; van Rooijen, Nico; van Calker, Dietrich; Biber, Knut

    2016-01-01

    Recently, we have demonstrated that ramified microglia are neuroprotective in N-methyl-D-aspartate (NMDA)-induced excitotoxicity in organotypic hippocampal slice cultures (OHSCs). The present study aimed to elucidate the underlying neuron-glia communication mechanism. It is shown here that pretreatment of OHSC with high concentrations of adenosine 5'-triphosphate (ATP) reduced NMDA-induced neuronal death only in presence of microglia. Specific agonists and antagonists identified the P2X7 receptor as neuroprotective receptor which was confirmed by absence of ATP-dependent neuroprotection in P2X7-deficient OHSC. Microglia replenished chimeric OHSC consisting of wild-type tissue replenished with P2X7-deficient microglia confirmed the involvement of microglial P2X7 receptor in neuroprotection. Stimulation of P2X7 in primary microglia induced tumor necrosis factor α (TNFα) release and blocking TNFα by a neutralizing antibody in OHSC abolished neuroprotection by ATP. OHSC from TNFα-deficient mice show increased exicitoxicity and activation of P2X7 did not rescue neuronal survival in the absence of TNFα. The neuroprotective effect of valproic acid (VPA) was strictly dependent on the presence of microglia and was mediated by upregulation of P2X7 in the cells. The present study demonstrates that microglia-mediated neuroprotection depends on ATP-activated purine receptor P2X7 and induction of TNFα release. This neuroprotective pathway was strengthened by VPA elucidating a novel mechanism for the neuroprotective function of VPA.

  19. P2X7 receptors mediate innate phagocytosis by human neural precursor cells and neuroblasts.

    Science.gov (United States)

    Lovelace, Michael D; Gu, Ben J; Eamegdool, Steven S; Weible, Michael W; Wiley, James S; Allen, David G; Chan-Ling, Tailoi

    2015-02-01

    During early human neurogenesis there is overproduction of neuroblasts and neurons accompanied by widespread programmed cell death (PCD). While it is understood that CD68(+) microglia and astrocytes mediate phagocytosis during target-dependent PCD, little is known of the cell identity or the scavenger molecules used to remove apoptotic corpses during the earliest stages of human neurogenesis. Using a combination of multiple-marker immunohistochemical staining, functional blocking antibodies and antagonists, we showed that human neural precursor cells (hNPCs) and neuroblasts express functional P2X7 receptors. Furthermore, using live-cell imaging, flow cytometry, phagocytic assays, and siRNA knockdown, we showed that in a serum-free environment, doublecortin(+) (DCX) neuroblasts and hNPCs can clear apoptotic cells by innate phagocytosis mediated via P2X7. We found that both P2X7(high) DCX(low) hNPCs and P2X7(high) DCX(high) neuroblasts, derived from primary cultures of human fetal telencephalon, phagocytosed targets including latex beads, apoptotic ReNcells, and apoptotic hNPC/neuroblasts. Pretreatment of neuroblasts and hNPCs with 1 mM adenosine triphosphate (ATP), 100 µM OxATP (P2X7 antagonist), or siRNA knockdown of P2X7 inhibited phagocytosis of these targets. Our results show that P2X7 functions as a scavenger receptor under serum-free conditions resembling those in early neurogenesis. This is the first demonstration that hNPCs and neuroblasts may participate in clearance of apoptotic corpses during pre target-dependent neurogenesis and mediate phagocytosis using P2X7 as a scavenger receptor.

  20. P2P相关技术的研究%Research of P2P technologies

    Institute of Scientific and Technical Information of China (English)

    李秀君; 李成

    2012-01-01

    Peer-to-Peer(P2P) is a virtual network that is based on the underlying communication network infrastructure,and is a self-organizing system which is distributed and interoperable.Now,the software with P2P technology is in widespread use,and brings the users happiness,at the same time,resulting in a waste of network bandwidth.In order to make P2P more efficient operation and reduce network flow,this paper introduces the theory of the P4P technology.Through the study of the P2P technology,this article points out the contradiction between the P2P application and network operator,and analyzes the solution in detail.%对等网络(P2P)是一种构筑于底层通信网络基础设施之上的虚拟网络,是一个分布式的、具有互操作性的自组织系统。现在,运用P2P技术的软件比比皆是,使人们在不知不觉中感受到了P2P技术带来的快乐,与此同时它也浪费了大量的网络带宽。为了让P2P系统更高效的运行,同时降低网络的流量,本文介绍了P4P技术的相关理论。通过对P2P技术的研究,指出了P2P应用与网络运营商之间的矛盾,并对其解决办法进行了详细的分析。

  1. The P2X7 receptor

    DEFF Research Database (Denmark)

    Kvist, Torben Madsen; Schwarz, Peter; Jørgensen, Niklas Rye

    2014-01-01

    from an increase in bone resorption and the pro-inflammatory cytokines tumor necrosis factor alpha and interleukin 1 beta and has been shown to not only mediate the inflammatory response but also to strongly stimulate bone degradation. The purinergic P2X7 receptor is central in the processing...... of these two cytokines and in the initiation of the inflammatory response, and it is a key molecule in the regulation of both bone formation and bone resorption. The aim of this review is therefore to provide evidence-based novel hypotheses of the role of ATP-mediated purinergic signalling via the P2X7...... receptor in immune-mediated bone loss and -osteoporosis....

  2. Data Sharing in P2P Systems

    Science.gov (United States)

    Hayek, Rabab; Raschia, Guillaume; Valduriez, Patrick; Mouaddib, Noureddine

    In this chapter, we survey P2P data sharing systems. All along, we focus on the evolution from simple file-sharing systems, with limited functionalities, to Peer Data Management Systems (PDMS) that support advanced applications with more sophisticated data management techniques. Advanced P2P applications are dealing with semantically rich data (e.g., XML documents, relational tables), using a high-level SQL-like query language. We start our survey with an overview over the existing P2P network architectures, and the associated routing protocols. Then, we discuss data indexing techniques based on their distribution degree and the semantics they can capture from the underlying data. We also discuss schema management techniques which allow integrating heterogeneous data. We conclude by discussing the techniques proposed for processing complex queries (e.g., range and join queries). Complex query facilities are necessary for advanced applications which require a high level of search expressiveness. This last part shows the lack of querying techniques that allow for an approximate query answering.

  3. Neuroprotective effects of inhibiting N-methyl-D-aspartate receptors, P2X receptors and the mitogen-activated protein kinase cascade: a quantitative analysis in organotypical hippocampal slice cultures subjected to oxygen and glucose deprivation.

    Science.gov (United States)

    Rundén-Pran, E; Tansø, R; Haug, F M; Ottersen, O P; Ring, A

    2005-01-01

    Cell death was assessed by quantitative analysis of propidium iodide uptake in rat hippocampal slice cultures transiently exposed to oxygen and glucose deprivation, an in vitro model of brain ischemia. The hippocampal subfields CA1 and CA3, and fascia dentata were analyzed at different stages from 0 to 48 h after the insult. Cell death appeared at 3 h and increased steeply toward 12 h. Only a slight additional increase in propidium iodide uptake was seen at later intervals. The mitogen-activated protein kinases extracellular signal-regulated kinase 1 and extracellular signal-regulated kinase 2 were activated immediately after oxygen and glucose deprivation both in CA1 and in CA3/fascia dentata. Inhibition of the specific mitogen-activated protein kinase activator mitogen-activated protein kinase kinase by PD98059 or U0126 offered partial protection against oxygen and glucose deprivation-induced cell damage. The non-selective P2X receptor antagonist suramin gave neuroprotection of the same magnitude as the N-methyl-D-aspartate channel blocker MK-801 (approximately 70%). Neuroprotection was also observed with the P2 receptor blocker PPADS. Immunogold data indicated that hippocampal slice cultures (like intact hippocampi) express several isoforms of P2X receptors at the synaptic level, consistent with the idea that the effects of suramin and PPADS are mediated by P2X receptors. Virtually complete neuroprotection was obtained by combined blockade of N-methyl-D-aspartate receptors, P2X receptors, and mitogen-activated protein kinase kinase. Both P2X receptors and N-methyl-D-aspartate receptors mediate influx of calcium. Our results suggest that inhibition of P2X receptors has a neuroprotective potential similar to that of inhibition of N-methyl-D-aspartate receptors. In contrast, our comparative analysis shows that only partial protection can be achieved by inhibiting the extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase cascade, one of the

  4. P2X purinoceptors as a link between hyperexcitability and neuroinflammation in status epilepticus.

    Science.gov (United States)

    Henshall, David C; Engel, Tobias

    2015-08-01

    There remains a need for more efficacious treatments for status epilepticus. Prolonged seizures result in the release of ATP from cells which activates the P2 class of ionotropic and metabotropic purinoceptors. The P2X receptors gate depolarizing sodium and calcium entry and are expressed by both neurons and glia throughout the brain, and a number of subtypes are upregulated after status epilepticus. Recent studies have explored the in vivo effects of targeting ATP-gated P2X receptors in preclinical models of status epilepticus, with particular focus on the P2X7 receptor (P2X7R). The P2X7R mediates microglial activation and the release of the proepileptogenic inflammatory cytokine interleukin 1β. The receptor may also directly modulate neurotransmission and gliotransmission and promote the recruitment of immune cells into brain parenchyma. Data from our group and collaborators show that status epilepticus produced by intraamygdala microinjection of kainic acid increases P2X7R expression in the hippocampus and neocortex of mice. Antagonism of the P2X7R in the model reduced seizure severity, microglial activation and interleukin 1β release, and neuronal injury. Coadministration of a P2X7R antagonist with a benzodiazepine also provided seizure suppression in a model of drug-refractory status epilepticus when either treatment alone was minimally effective. More recently, we showed that status epilepticus in immature rats is also reduced by P2X7R antagonism. Together, these findings suggest that P2X receptors may be novel targets for seizure control and interruption of neuroinflammation after status epilepticus. This article is part of a Special Issue entitled "Status Epilepticus".

  5. Targeting of the P2X7 receptor in pancreatic cancer and stellate cells.

    Science.gov (United States)

    Giannuzzo, Andrea; Saccomano, Mara; Napp, Joanna; Ellegaard, Maria; Alves, Frauke; Novak, Ivana

    2016-12-01

    The ATP-gated receptor P2X7 (P2X7R) is involved in regulation of cell survival and has been of interest in cancer field. Pancreatic ductal adenocarcinoma (PDAC) is a deadly cancer and new markers and therapeutic targets are needed. PDAC is characterized by a complex tumour microenvironment, which includes cancer and pancreatic stellate cells (PSCs), and potentially high nucleotide/side turnover. Our aim was to determine P2X7R expression and function in human pancreatic cancer cells in vitro as well as to perform in vivo efficacy study applying P2X7R inhibitor in an orthotopic xenograft mouse model of PDAC. In the in vitro studies we show that human PDAC cells with luciferase gene (PancTu-1 Luc cells) express high levels of P2X7R protein. Allosteric P2X7R antagonist AZ10606120 inhibited cell proliferation in basal conditions, indicating that P2X7R was tonically active. Extracellular ATP and BzATP, to which the P2X7R is more sensitive, further affected cell survival and confirmed complex functionality of P2X7R. PancTu-1 Luc migration and invasion was reduced by AZ10606120, and it was stimulated by PSCs, but not by PSCs from P2X7(-/-) animals. PancTu-1 Luc cells were orthotopically transplanted into nude mice and tumour growth was followed noninvasively by bioluminescence imaging. AZ10606120-treated mice showed reduced bioluminescence compared to saline-treated mice. Immunohistochemical analysis confirmed P2X7R expression in cancer and PSC cells, and in metaplastic/neoplastic acinar and duct structures. PSCs number/activity and collagen deposition was reduced in AZ10606120-treated tumours.

  6. The absence of P2X7 receptors (P2rx7) on non-haematopoietic cells leads to selective alteration in mood-related behaviour with dysregulated gene expression and stress reactivity in mice.

    Science.gov (United States)

    Csölle, Cecilia; Andó, Rómeó D; Kittel, Ágnes; Gölöncsér, Flóra; Baranyi, Mária; Soproni, Krisztina; Zelena, Dóra; Haller, József; Németh, Tamás; Mócsai, Attila; Sperlágh, Beáta

    2013-02-01

    The purpose of this study was to explore how genetic deletion and pharmacological antagonism of the P2X7 receptor (P2rx7) alter mood-related behaviour, gene expression and stress reactivity in the brain. The forced swim test (FST), tail suspension test (TST) and amphetamine-induced hyperlocomotion (AH) tests were used in wild-type (P2rx7(+/+)) and P2rx7-deficient (P2rx7(-/-)) mice. Biogenic amine levels were analysed in the amygdala and striatum, adrenocorticotropic hormone (ACTH) and corticosterone levels were measured in the plasma and pituitary after restraint stress. Chimeric mice were generated by bone marrow transplantation. A whole genome microarray analysis with real-time polymerase chain reaction validation was performed on the amygdala. In the absence of P2rx7s decreased behavioural despair in the FST, reduced immobility in the TST and attenuated amphetamine-induced hyperactivity were detected. Basal norepinephrine levels were elevated in the amygdala, whereas stress-induced ACTH and corticosterone responses were alleviated in P2rx7(-/-) mice. Sub-acute treatment with the selective P2rx7 antagonist, Brilliant Blue G, reproduced the effect of genetic deletion in the TST and AH test in P2rx7(+/+) but not P2rx7(-/-) mice. No change in behavioural phenotype was observed in chimeras lacking the P2rx7 in their haematopoietic compartment. Whole genome microarray analysis indicated a widespread up- and down-regulation of genes crucial for synaptic function and neuroplasticity by genetic deletion. Here, we present evidence that the absence of P2rx7s on non-haematopoietic cells leads to a mood-stabilizing phenotype in several behavioural models and suggest a therapeutic potential of P2rx7 antagonists for the treatment of mood disorders.

  7. Can non-selective beta-blockers prevent hepatocellular carcinoma in patients with cirrhosis?

    DEFF Research Database (Denmark)

    Thiele, Maja; Wiest, Reiner; Gluud, Lise Lotte

    2013-01-01

    Hepatocellular carcinoma is the main liver-related cause of death in patients with compensated cirrhosis. The early phases are asymptomatic and the prognosis is poor, which makes prevention essential. We propose that non-selective beta-blockers decrease the incidence and growth of hepatocellular...... carcinoma via a reduction of the inflammatory load from the gut to the liver and inhibition of angiogenesis. Due to their effect on the portal pressure, non-selective beta-blockers are used for prevention of esophageal variceal bleeding. Recently, non-hemodynamic effects of beta-blockers have received...... reduce hepatic inflammation. Blockage of β-adrenoceptors also decrease angiogenesis by inhibition of vascular endothelial growth factors. Because gut-derived inflammation and neo-angiogenesis are important in hepatic carcinogenesis, non-selective beta-blockers can potentially reduce the development...

  8. Quantifying Ca2+ current and permeability in ATP-gated P2X7 receptors.

    Science.gov (United States)

    Liang, Xin; Samways, Damien S K; Wolf, Kyle; Bowles, Elizabeth A; Richards, Jennifer P; Bruno, Jonathan; Dutertre, Sébastien; DiPaolo, Richard J; Egan, Terrance M

    2015-03-20

    ATP-gated P2X7 receptors are prominently expressed in inflammatory cells and play a key role in the immune response. A major consequence of receptor activation is the regulated influx of Ca(2+) through the self-contained cation non-selective channel. Although the physiological importance of the resulting rise in intracellular Ca(2+) is universally acknowledged, the biophysics of the Ca(2+) flux responsible for the effects are poorly understood, largely because traditional methods of measuring Ca(2+) permeability are difficult to apply to P2X7 receptors. Here we use an alternative approach, called dye-overload patch-clamp photometry, to quantify the agonist-gated Ca(2+) flux of recombinant P2X7 receptors of dog, guinea pig, human, monkey, mouse, rat, and zebrafish. We find that the magnitude of the Ca(2+) component of the ATP-gated current depends on the species of origin, the splice variant, and the concentration of the purinergic agonist. We also measured a significant contribution of Ca(2+) to the agonist-gated current of the native P2X7Rs of mouse and human immune cells. Our results provide cross-species quantitative measures of the Ca(2+) current of the P2X7 receptor for the first time, and suggest that the cytoplasmic N terminus plays a meaningful role in regulating the flow of Ca(2+) through the channel.

  9. P2X7R activation drives distinct IL-1 responses in dendritic cells compared to macrophages.

    Science.gov (United States)

    Englezou, Pavlos C; Rothwell, Simon W; Ainscough, Joseph S; Brough, David; Landsiedel, Robert; Verkhratsky, Alexei; Kimber, Ian; Dearman, Rebecca J

    2015-08-01

    The P2X(7)R is a functionally distinct member of the P2X family of non-selective cation channels associated with rapid activation of the inflammasome complex and signalling interleukin (IL)-1β release in macrophages. The main focus of this investigation was to compare P2X(7)R-driven IL-1 production by primary murine bone marrow derived dendritic cells (BMDC) and macrophages (BMM). P2X(7)R expression in murine BMDC and BMM at both transcriptional (P2X(7)A variant) and protein levels was demonstrated. Priming with lipopolysaccharide (LPS) and receptor activation with adenosine triphosphate (ATP) resulted in markedly enhanced IL-1 (α and β) secretion in BMDC compared with BMM. In both cell types IL-1 production was profoundly inhibited with a P2X(7)R-specific inhibitor (A-740003) demonstrating that this release is predominantly a P2X(7)R-dependent process. These data also suggest that P2X(7)R and caspase-1 activation drive IL-1α release from BMDC. Both cell types expressed constitutively the gain-of-function P2X(7)K as well as the full P2X(7)A variant at equivalent levels. LPS priming reduced significantly levels of P2X(7)A but not P2X(7)K transcripts in both BMDC and BMM. P2X(7)R-induced pore formation, assessed by YO-PRO-1 dye uptake, was greater in BMDC, and these cells were protected from cell death. These data demonstrate that DC and macrophages display distinct patterns of cytokine regulation, particularly with respect to IL-1, as a consequence of cell-type specific differences in the physicochemical properties of the P2X(7)R. Understanding the cell-specific regulation of these cytokines is essential for manipulating such responses in health and disease.

  10. How to sell successfully a perfume in the non-selective market?

    OpenAIRE

    Ramalho, Maria Rita Pinto Coelho de Magalhães

    2009-01-01

    A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics This document presents a market research on the positioning of perfumes in the non selective market. This project’s main goal had been to analyze the challenge of “successfully selling a perfume in the non-selective market” in order to propose potential solutions. To address this marketing problem, an exploratory research had been c...

  11. Eclogitic pyroxenes, ordered with p2 symmetry.

    Science.gov (United States)

    Clark, J R; Papike, J J

    1966-11-25

    X-ray diffraction crystal-structure analysis of omphacite from eclogite, Tiburon Peninsula, Marin County, California, shows that this clinopyroxene has P2 symmetry with a nearly ordered distribution of the multiple cation content defined by its approximate formula: (Na(o.5) Ca(o.5)) (Mg(o.4)Fe(2)+( 0.1) Al(0.4) Fe(3) +(0.1)) Si(2)0(6). Na+ and Ca(2+) tend to assume alternate locations in the structure, and ( Mg,Fe(2+)) octahedra alternate with Al(3+). or (Al,F(3+)) octahedra in chains along c.

  12. Magnetotransport properties of MoP$_2$

    OpenAIRE

    Wang, Aifeng; Graf, D.; Liu, Yu; Petrovic, C.

    2017-01-01

    We report magnetotransport and de Haas-van Alphen (dHvA) effect studies on MoP$_2$ single crystals, predicted to be type-2 Weyl semimetal with four pairs of robust Weyl points located below the Fermi level and long Fermi arcs. The temperature dependence of resistivity shows a peak before saturation, which does not move with magnetic field. Large nonsaturating magnetoresistance (MR) was observed, and the field dependence of MR exhibits a crossover from semicalssical weak-field $B^2$ dependence...

  13. Python passive network mapping P2NMAP

    CERN Document Server

    Hosmer, Chet

    2015-01-01

    Python Passive Network Mapping: P2NMAP is the first book to reveal a revolutionary and open source method for exposing nefarious network activity. The ""Heartbleed"" vulnerability has revealed significant weaknesses within enterprise environments related to the lack of a definitive mapping of network assets. In Python Passive Network Mapping, Chet Hosmer shows you how to effectively and definitively passively map networks. Active or probing methods to network mapping have traditionally been used, but they have many drawbacks - they can disrupt operations, crash systems, and - most important

  14. The new INNOVANCE® PFA P2Y cartridge is sensitive to the detection of the P2Y₁₂ receptor inhibition.

    Science.gov (United States)

    Koessler, Juergen; Kobsar, Anna L; Rajkovic, Mirjana S; Schafer, Andreas; Flierl, Ulrike; Pfoertsch, Stephanie; Bauersachs, Johann; Steigerwald, Udo; Rechner, Andreas R; Walter, Ulrich

    2011-01-01

    Insufficient response on antiplatelet medication has become an intensively discussed issue because of the risk factor of recurrent adverse cardiovascular events. However, the monitoring of antiplatelet therapy requires appropriate, robust and reliable test methods. For the measurement of thienopyridine effects, the manufacturer of the PFA-100® System provides the INNOVANCE® PFA P2Y * cartridge. We tested this cartridge for its capacity to detect the inhibition of the P2Y₁₂ receptor, which is the target for thienopyridine medication (e.g. clopidogrel). We compared the INNOVANCE® PFA P2Y * results with those obtained by the receptor specific flow cytometric vasodilator stimulated phosphoprotein (VASP) assay that expresses the status of the P2Y₁₂ receptor as "platelet reactivity index" (PRI). The in vitro addition of the P2Y₁₂ receptor antagonist cangrelor (AR-C69931MX) to citrated human whole blood resulted in a dose-dependent prolongation of closure times (CTs) of the INNOVANCE® PFA P2Y * cartridge correlating with decreased PRI levels. In volunteers, the intake of a 600 mg clopidogrel loading dose caused an increase of the CTs in all volunteers, although some of these volunteers were identified as "poor responders" by the VASP assay (no significant reduction of PRI levels). In 50 patients with stable coronary artery disease undergoing percutaneous coronary intervention (PCI) and under dual antiplatelet therapy, the new cartridge had a detection rate of 84% (CT 106 s as cut-off) for clopidogrel medication. After dividing the 50 patients into two groups according to their response to clopidogrel INNOVANCE® PFA P2Y * recognized all "responders" (defined by a PRI > 50%) using >106 s as cut-off but the specificity for a "good response" was only 42% because several "poor responders" (defined by a PRI > 50%) also showed CTs above the cut-off. The best correlation (substantial agreement) between the results of INNOVANCE® PFA P2Y * and of the VASP

  15. Role of P2X7 and P2Y2 receptors on α-secretase-dependent APP processing: Control of amyloid plaques formation “in vivo” by P2X7 receptor

    Directory of Open Access Journals (Sweden)

    M. Teresa Miras-Portugal

    2015-01-01

    The in vivo approach was made possible by the use of J20 mice, a transgenic mouse model of familial Alzheimer's disease (FAD expressing human APP mutant protein. This animal exhibits prominent amyloid plaques by six months of age. In vivo inhibition of the P2X7 receptor induced a significant decrease in the number and size of hippocampal amyloid plaques. This reduction is mediated by an increase in the proteolytic processing of APP through α-secretase activity, which correlates with an increase in the phosphorylated form of GSK-3, a less active form of this enzyme. The in vivo findings corroborate the therapeutic potential of P2X7 antagonists in the treatment of FAD.

  16. Involvement of P2X7 receptor in neuronal degeneration triggered by traumatic injury

    Science.gov (United States)

    Nadal-Nicolás, Francisco M.; Galindo-Romero, Caridad; Valiente-Soriano, Francisco J.; Barberà-Cremades, María; deTorre-Minguela, Carlos; Salinas-Navarro, Manuel; Pelegrín, Pablo; Agudo-Barriuso, Marta

    2016-01-01

    Axonal injury is a common feature of central nervous system insults that culminates with the death of the affected neurons, and an irreversible loss of function. Inflammation is an important component of the neurodegenerative process, where the microglia plays an important role by releasing proinflammatory factors as well as clearing the death neurons by phagocytosis. Here we have identified the purinergic signaling through the P2X7 receptor as an important component for the neuronal death in a model of optic nerve axotomy. We have found that in P2X7 receptor deficient mice there is a delayed loss of retinal ganglion cells and a decrease of phagocytic microglia at early times points after axotomy. In contralateral to the axotomy retinas, P2X7 receptor controlled the numbers of phagocytic microglia, suggesting that extracellular ATP could act as a danger signal activating the P2X7 receptor in mediating the loss of neurons in contralateral retinas. Finally, we show that intravitreal administration of the selective P2X7 receptor antagonist A438079 also delays axotomy-induced retinal ganglion cell death in retinas from wild type mice. Thus, our work demonstrates that P2X7 receptor signaling is involved in neuronal cell death after axonal injury, being P2X7 receptor antagonism a potential therapeutic strategy. PMID:27929040

  17. Targeting of the P2X7 receptor in pancreatic cancer and stellate cells

    DEFF Research Database (Denmark)

    Giannuzzo, Andrea; Saccomano, Mara; Napp, Joanna;

    2016-01-01

    The ATP-gated receptor P2X7 (P2X7R) is involved in regulation of cell survival and has been of interest in cancer field. Pancreatic ductal adenocarcinoma (PDAC) is a deadly cancer and new markers and therapeutic targets are needed. PDAC is characterized by a complex tumour microenvironment, which...... includes cancer and pancreatic stellate cells (PSCs), and potentially high nucleotide/side turnover. Our aim was to determine P2X7R expression and function in human pancreatic cancer cells in vitro as well as to perform in vivo efficacy study applying P2X7R inhibitor in an orthotopic xenograft mouse model...... of PDAC. In the in vitro studies we show that human PDAC cells with luciferase gene (PancTu-1 Luc cells) express high levels of P2X7R protein. Allosteric P2X7R antagonist AZ10606120 inhibited cell proliferation in basal conditions, indicating that P2X7R was tonically active. Extracellular ATP and Bz...

  18. P2X receptors mediate ATP-induced primary nociceptive neurone activation.

    Science.gov (United States)

    Bland-Ward, P A; Humphrey, P P

    2000-07-01

    ATP-gated P2X ion-channel receptors are localised throughout the mammalian nervous system and have been identified on neurones which participate in conduction of nociceptive information from the periphery to, and within, the CNS. This article briefly reviews recently published research describing the role that ATP and P2X receptors may play in pain perception, highlighting the importance of the P2X(3) receptor in this process. The P2X(3) receptor subunit is almost exclusively expressed on a subset of small and medium diameter sensory neurones innervating cutaneous and visceral tissue. Activation of P2X receptors present on the peripheral terminals of primary afferents results in neuronal depolarisation and, in conscious animals, leads to the manifestation of acute nociceptive behaviour. Recent animal studies have also shown that P2X(3) receptor expression is increased in sensory ganglia following acute neuronal injury, hinting that similar plasticity in the expression of this receptor subtype could underlie the mechanisms involved in a range of conditions characterised by sensory hypersensitivity in man. It is apparent from the evidence available that functional antagonists at specific P2X receptor subtypes could represent an important class of novel analgesic agents.

  19. Blockade of P2X7 receptors or pannexin-1 channels similarly attenuates postischemic damage.

    Science.gov (United States)

    Cisneros-Mejorado, Abraham; Gottlieb, Miroslav; Cavaliere, Fabio; Magnus, Tim; Koch-Nolte, Friederich; Scemes, Eliana; Pérez-Samartín, Alberto; Matute, Carlos

    2015-05-01

    The role of P2X7 receptors and pannexin-1 channels in ischemic damage remains controversial. Here, we analyzed their contribution to postanoxic depolarization after ischemia in cultured neurons and in brain slices. We observed that pharmacological blockade of P2X7 receptors or pannexin-1 channels delayed the onset of postanoxic currents and reduced their slope, and that simultaneous inhibition did not further enhance the effects of blocking either one. These results were confirmed in acute cortical slices from P2X7 and pannexin-1 knockout mice. Oxygen-glucose deprivation in cortical organotypic cultures caused neuronal death that was reduced with P2X7 and pannexin-1 blockers as well as in organotypic cultures derived from mice lacking P2X7 and pannexin 1. Subsequently, we used transient middle cerebral artery occlusion to monitor the neuroprotective effect of those drugs in vivo. We found that P2X7 and pannexin-1 antagonists, and their ablation in knockout mice, substantially attenuated the motor symptoms and reduced the infarct volume to ~50% of that in vehicle-treated or wild-type animals. These results show that P2X7 receptors and pannexin-1 channels are major mediators of postanoxic depolarization in neurons and of brain damage after ischemia, and that they operate in the same deleterious signaling cascade leading to neuronal and tissue demise.

  20. P2X7 Receptor Mediated Growth-Inhibitory Effect in KG1 a Cell Line

    Institute of Scientific and Technical Information of China (English)

    Xiujun Zhang; Lijun Meng

    2008-01-01

    This study was conducted to investigate ATP-induced growth inhibition in human leukemic cells KGla.METHoDS ATP inhibited cell growth was analyzed by MTSassay.Extemalization of phosphatidylserine could be detected byAnnexin-V-FITC apoptosis staining after activation of the P2X7 re-ceptor.P2X7 mediated pore formation was detected in KGla cellsby Yo-Pro-1 uptake assay.RESUlTS ATP inhibited cell growth in a dose-dependent man-ner.The cytotoxic effect could be blocked by P2X7 antagonists,oxidized ATP(OATP)and KN62.Externalization of phosphatidyl-serine could be detected in a time-dependent manner.P2X7 medi-ated pore forigation could be detected in KGla cells.These effectscould not be observed in P2X7 null Ramos cells.CONCLUSIoN The results and our previously reports thatmRNA,protein expression and calcium response of the P2X7receptor in KGla cells,suggested that extracellular ATP effectivelyinduces growth inhibition through apoptosis in KGla cells byactivation of P2X7 receptor,and that may be mediated by extracel-lular Ca2+ineux and pore formation.

  1. P2X7 receptor-mediated analgesia in cancer-induced bone pain

    DEFF Research Database (Denmark)

    Falk, Sarah; D. Schwab, Samantha; Frøsig-Jørgensen, Majbrit

    2015-01-01

    for cancer-induced bone pain. The P2X7 receptor (P2X7R) is involved in a variety of cellular functions and has been linked to both inflammatory and neuropathic pain. Here we study the analgesic potential of P2X7 receptor antagonism in a rat model of cancer-induced bone pain. In cancer-bearing animals, the P2....... The results suggest that the P2X7R is involved in the mechanisms of cancer-induced bone pain, and that P2X7R antagonism might be a useful analgesic target. No effect was observed in sham or naïve animals, indicating that the P2X7R-mediated effect is state-dependent, and might therefore be an advantageous......X7R antagonist A839977 attenuated dorsal horn neuronal responses in a modality and intensity specific way. Spinal application of 0.4mg/kg and 1.2mg/kg A839977 significantly reduced the evoked responses to high intensity mechanical and thermal stimulation, whereas no effect was seen in response...

  2. Targeting of the P2X7 receptor in pancreatic cancer and stellate cells

    DEFF Research Database (Denmark)

    Giannuzzo, Andrea; Saccomano, Mara; Napp, Joanna

    2016-01-01

    The ATP-gated receptor P2X7 (P2X7R) is involved in regulation of cell survival and has been of interest in cancer field. Pancreatic ductal adenocarcinoma (PDAC) is a deadly cancer and new markers and therapeutic targets are needed. PDAC is characterized by a complex tumour microenvironment, which...... includes cancer and pancreatic stellate cells (PSCs), and potentially high nucleotide/side turnover. Our aim was to determine P2X7R expression and function in human pancreatic cancer cells in vitro as well as to perform in vivo efficacy study applying P2X7R inhibitor in an orthotopic xenograft mouse model...... of PDAC. In the in vitro studies we show that human PDAC cells with luciferase gene (PancTu-1 Luc cells) express high levels of P2X7R protein. Allosteric P2X7R antagonist AZ10606120 inhibited cell proliferation in basal conditions, indicating that P2X7R was tonically active. Extracellular ATP and Bz...

  3. Lymphocytes from P2X7-deficient mice exhibit enhanced P2X7 responses

    OpenAIRE

    Simon R.J. Taylor; Gonzalez-Begne, Mireya; Sojka, Dorothy K.; Richardson, Jill C.; Sheardown, Steven A.; Harrison, Stephen M; Pusey, Charles D.; Tam, Frederick W. K.; Elliott, James I

    2009-01-01

    The purinergic receptor P2X7 is expressed on immune cells, and its stimulation results in the release of IL-1β from macrophages. Its absence, as evidenced from the analysis of two independent strains of P2X7-deficient mice, results in reduced susceptibility to inflammatory disease, and the molecule is an important, potential therapeutic target in autoimmunity. However, P2X7 has also been detected in several neuronal cell types, although its function and even its presence in these cells are hi...

  4. CCQE, 2p2h excitations and \

    CERN Document Server

    Nieves, J; Sánchez, F; Vacas, M J Vicente

    2013-01-01

    We analyze the MiniBooNE muon neutrino CCQE-like d\\sigma/dT_\\mu/dcos\\theta_\\mu data using a theoretical model that, among other nuclear effects, includes RPA correlations and 2p2h (multinucleon) mechanisms. These corrections turn out to be essential for the description of the data. We find that MiniBooNE CCQE-like data are fully compatible with former determinations of the nucleon axial mass M_A ~ 1.05 GeV. This is in sharp contrast with several previous analysis where anomalously large values of M_A ~ 1.4 GeV have been suggested. We also show that because of the the multinucleon mechanism effects, the algorithm used to reconstruct the neutrino energy is not adequate when dealing with quasielastic-like events. Finally, we analyze the MiniBooNE unfolded cross section, and show that it exhibits an excess (deficit) of low (high) energy neutrinos, which is an artifact of the unfolding process that ignores 2p2h mechanisms.

  5. Track reconstruction for the P2 experiment

    Energy Technology Data Exchange (ETDEWEB)

    Tyukin, Alexey [JGU, Mainz (Germany); Collaboration: P2-Collaboration

    2016-07-01

    The P2 experiment at the future MESA accelerator in Mainz will measure elastically scattered electrons from a hydrogen or lead target in order to determine the parity violating asymmetry for different beam polarisations, which is created due to the weak charge of the target. The asymmetry can provide access to the Weinberg angle and the neutron skin of heavy nuclei. These quantities depend heavily on the momentum transfer Q{sup 2}, thus a reconstruction of single electron tracks in an inhomogeneous magnetic field is necessary. For this, the P2 detector will have four tracking planes of thin high voltage monolithic active pixel sensors (HV-MAPS). The scattered electrons propagate through a magnetic field and hit all four planes. In order to fit the hit positions the General Broken Lines method is used. As a fast propagator, a variation of the Runge-Kutta algorithm is applied, which solves the equation of motion in an inhomogeneous magnetic field numerically, such that the final state momentum and scattering angle can be reconstructed. The initial momentum and incident angle can vary strongly due to the thickness of the target, limiting the reconstruction quality. The average single track Q{sup 2} value of 0.006 GeV{sup 2}/c{sup 2} can be reconstructed with about 4 % uncertainty in a first analysis of the Geant4 simulation, leading to a high total precision due to large electron numbers in the experiment.

  6. P2X receptors as targets for the treatment of status epilepticus

    Directory of Open Access Journals (Sweden)

    David C Henshall

    2013-11-01

    Full Text Available Prolonged seizures are amongst the most common neurological emergencies. Status epilepticus is a state of continuous seizures that is life-threatening and prompt termination of status epilepticus is critical to protect the brain from permanent damage. Frontline treatment comprises parenteral administration of anticonvulsants such as lorazepam that facilitate γ-amino butyric acid (GABA transmission. Because status epilepticus can become refractory to anticonvulsants in a significant proportion of patients, drugs which act on different neurotransmitter systems may represent potential adjunctive treatments. P2X receptors are a class of ligand-gated ion channel activated by ATP that contributes to neuro- and glio-transmission. P2X receptors are expressed by both neurons and glia in various brain regions, including the hippocampus. Electrophysiology, pharmacology and genetic studies suggest certain P2X receptors are activated during pathologic brain activity. Expression of several members of the family including P2X2, P2X4 and P2X7 receptors has been reported to be altered in the hippocampus following status epilepticus. Recent studies have shown that ligands of the P2X7 receptor can have potent effects on seizure severity during status epilepticus and mice lacking this receptor display altered seizures in response to chemoconvulsants. Antagonists of the P2X7 receptor also modulate neuronal death, microglial responses and neuroinflammatory signaling. Recent work also found altered neuronal injury and inflammation after status epilepticus in mice lacking the P2X4 receptor. In summary, members of the P2X receptor family may serve important roles in the pathophysiology of status epilepticus and represent novel targets for seizure control and neuroprotection.

  7. Contribution of the spinal P2X7 receptors to bee venom-induced nociception and inflammation in conscious rats.

    Science.gov (United States)

    Zhou, Zhong-He; Wang, Jian-Xiu; Liu, Bao-Jun; Li, Man; Lu, Yao; Chen, Hui-Sheng

    2012-12-07

    Recently, P2X7 receptor (P2X7R) has been found to contribute to the development of inflammatory pain, however, the role of spinal P2X7R is not clear. The present study was designed to determine the roles of spinal P2X7R in the bee venom (BV) model, characterized by multiple pain-related behaviors and obvious inflammatory edema. We determined the effects of P2X7R antagonist A438790 on BV-induced PSN, mechanical allodynia and inflammatory swelling. Pre-treatment with intrathecal administration of A438079 significantly inhibited BV-induced PSN and mechanical allodynia in a dose-dependent manner, but had no effect on BV-induced inflammatory swelling. These data suggest that the activation of spinal P2X7Rs may play a key role in BV-induced nociception, but not inflammation.

  8. CCR2 antagonists.

    Science.gov (United States)

    Struthers, Mary; Pasternak, Alexander

    2010-01-01

    Inhibition of CCR2 has been considered as a target for multiple therapeutic diseases including autoimmune disease, atherosclerosis, pain, and metabolic disease, based in part on the critical role this receptor plays on monocyte migration. Numerous companies have reported programs to identify CCR2 antagonists. Common challenges to the development of CCR2 agents have included poor activity at the rodent receptor and selectivity for both other chemokine receptors and ion channels. This review summarizes the rationale for targeting CCR2 in disease, the recent progress in the identification of potent and select CCR2 antagonists, and the current status of clinical trials for CCR2 agents.

  9. Lack of run-down of smooth muscle P2X receptor currents recorded with the amphotericin permeabilized patch technique, physiological and pharmacological characterization of the properties of mesenteric artery P2X receptor ion channels.

    Science.gov (United States)

    Lewis, C J; Evans, R J

    2000-12-01

    Immunoreactivity for P2X(1), P2X(4) and P2X(5) receptor subtypes was detected in the smooth muscle cell layer of second and third order rat mesenteric arteries immunoreactivity, for P2X(2), P2X(3), P2X(6) and P2X(7) receptors was below the level of detection in the smooth muscle layer. P2X receptor-mediated currents were recorded in patch clamp studies on acutely dissociated mesenteric artery smooth muscle cells. Purinergic agonists evoked transient inward currents that decayed rapidly in the continued presence of agonist (tau approximately 200 ms). Standard whole cell responses to repeated applications of agonist at 5 min intervals ran down. Run-down was unaffected by changes in extracellular calcium concentration, intracellular calcium buffering or the inclusion of ATP and GTP in the pipette solution. Run-down was overcome and reproducible responses to purinergic agonists were recorded using the amphotericin permeabilized patch recording configuration. The rank order of potency at the P2X receptor was ATP=2 methylthio ATP>alpha, beta-methylene ATP>CTP=l-beta,gamma-methylene ATP. Only ATP and 2meSATP were full agonists. The P2 receptor antagonists suramin and PPADS inhibited P2X receptor-mediated currents with IC(50)s of 4 microM and 70 nM respectively. These results provide further characterization of artery P2X receptors and demonstrate that the properties are dominated by a P2X(1)-like receptor phenotype. No evidence could be found for a phenotype corresponding to homomeric P2X(4) or P2X(5) receptors or to heteromeric P2X(1/5) receptors and the functional role of these receptors in arteries remains unclear.

  10. Lidocaine preferentially inhibits the function of purinergic P2X7 receptors expressed in Xenopus oocytes.

    Science.gov (United States)

    Okura, Dan; Horishita, Takafumi; Ueno, Susumu; Yanagihara, Nobuyuki; Sudo, Yuka; Uezono, Yasuhito; Minami, Tomoko; Kawasaki, Takashi; Sata, Takeyoshi

    2015-03-01

    Lidocaine has been widely used to relieve acute pain and chronic refractory pain effectively by both systemic and local administration. Numerous studies reported that lidocaine affects several pain signaling pathways as well as voltage-gated sodium channels, suggesting the existence of multiple mechanisms underlying pain relief by lidocaine. Some extracellular adenosine triphosphate (ATP) receptor subunits are thought to play a role in chronic pain mechanisms, but there have been few studies on the effects of lidocaine on ATP receptors. We studied the effects of lidocaine on purinergic P2X3, P2X4, and P2X7 receptors to explore the mechanisms underlying pain-relieving effects of lidocaine. We investigated the effects of lidocaine on ATP-induced currents in ATP receptor subunits, P2X3, P2X4, and P2X7 expressed in Xenopus oocytes, by using whole-cell, two-electrode, voltage-clamp techniques. Lidocaine inhibited ATP-induced currents in P2X7, but not in P2X3 or P2X4 subunits, in a concentration-dependent manner. The half maximal inhibitory concentration for lidocaine inhibition was 282 ± 45 μmol/L. By contrast, mepivacaine, ropivacaine, and bupivacaine exerted only limited effects on the P2X7 receptor. Lidocaine inhibited the ATP concentration-response curve for the P2X7 receptor via noncompetitive inhibition. Intracellular and extracellular N-(2,6-dimethylphenylcarbamoylmethyl) triethylammonium bromide (QX-314) and benzocaine suppressed ATP-induced currents in the P2X7 receptor in a concentration-dependent manner. In addition, repetitive ATP treatments at 5-minute intervals in the continuous presence of lidocaine revealed that lidocaine inhibition was use-dependent. Finally, the selective P2X7 receptor antagonists Brilliant Blue G and AZ11645373 did not affect the inhibitory actions of lidocaine on the P2X7 receptor. Lidocaine selectively inhibited the function of the P2X7 receptor expressed in Xenopus oocytes. This effect may be caused by acting on sites in the ion

  11. Non-selective β-blockers do not affect mortality in cirrhosis patients with ascites

    DEFF Research Database (Denmark)

    Bossen, Lars; Krag, Aleksander; Vilstrup, Hendrik

    2016-01-01

    The safety of non-selective β-blockers (NSBBs) in advanced cirrhosis has been questioned. We used data from three satavaptan trials to examine whether NSBBs increase mortality in cirrhosis patients with ascites. The trials were conducted in 2006-2008 and included 1198 cirrhosis patients with asci...

  12. Non-selective beta-blockers decrease thrombotic events in patients with heart failure

    NARCIS (Netherlands)

    De Peuter, Olav R.; Souverein, Patrick C.; Klungel, Olaf H.; Lip, Gregory Y.; Buller, Harry R.; De Boer, Anthonius; Kamphuisen, Pieter W.

    2010-01-01

    Background: Beta-blockers are often prescribed to patients with heart failure (HF) without distinctions between types of beta-blockers. The 2002 COMET study showed superiority of carvedilol (a non-selective beta-blocker) over metoprolol (selective beta-blocker) on mortality and cardiovascular events

  13. Increase of intracellular Ca2+ by P2Y but not P2X receptors in cultured cortical multipolar neurons of the rat.

    Science.gov (United States)

    Fischer, Wolfgang; Nörenberg, Wolfgang; Franke, Heike; Schaefer, Michael; Illes, Peter

    2009-10-10

    The expression and functionality of P2X/P2Y receptor subtypes in multipolar nonpyramidal neurons of mixed cortical cell cultures were investigated by means of immunocytochemistry and fura-2 microfluorimetry. The morphological studies revealed that most of the neurons are immunoreactive for GABA and express a range of P2X/P2Y receptors, predominantly of the P2X(2,4,6) and P2Y(1,2) subtypes. P2X(1) and P2X(7) receptor immunoreactivity (IR) was found on thin axon-like processes and presynaptic structures, respectively. Application of ATP caused a small concentration-dependent increase in intracellular Ca2+ concentration ([Ca2+]i) in most investigated neurons, whereas only about the half of these cells responded to 2',3'-O-(benzoyl-4-benzoyl)-ATP (BzATP), ADPbetaS, 2MeSADP, or 2MeSATP and even fewer cells to UTP. In contrast, alpha,beta-meATP, UDP, and UDP-glucose failed to produce any [Ca2+]i signaling. The response to ATP itself was inhibited by pyridoxal-5'-phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), Reactive Blue 2, 2'-deoxy-N(6)-methyl adenosine 3',5'-diphosphate (MRS2179), and suramin (300 microM) as well as by a cyclopiazonic acid-induced depletion of intracellular Ca2+ stores. A Ca2+-free external medium tended to decrease the ATP-induced [Ca2+]i transients, although this action did not reach statistical significance. Various blockers of voltage-sensitive Ca2+ channels and the gap junction inhibitor carbenoxolone did not interfere with the effect of ATP, whereas a combination of the ionotropic glutamate receptor antagonists D(-)-2-amino-5-phosphonopentanoic acid (AP5) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) decreased it. Cross-desensitization experiments between ADPbetaS or UTP and ATP suggested that ATP acts on the one hand via P2Y(1,2) receptors and on the other hand by additional signaling mechanisms. These mechanisms may involve the release of glutamate (which in consequence activates ionotropic glutamate receptors) and the entry of Ca2

  14. Autocrine Regulation of UVA-Induced IL-6 Production via Release of ATP and Activation of P2Y Receptors.

    Directory of Open Access Journals (Sweden)

    Ayumi Kawano

    Full Text Available Extracellular nucleotides, such as ATP, are released from cells in response to various stimuli and act as intercellular signaling molecules through activation of P2 receptors. Exposure to the ultraviolet radiation A (UVA component of sunlight causes molecular and cellular damage, and in this study, we investigated the involvement of extracellular nucleotides and P2 receptors in the UVA-induced cellular response. Human keratinocyte-derived HaCaT cells were irradiated with a single dose of UVA (2.5 J/cm2, and ATP release and interleukin (IL-6 production were measured. ATP was released from cells in response to UVA irradiation, and the release was blocked by pretreatment with inhibitors of gap junction hemichannels or P2X7 receptor antagonist. IL-6 production was increased after UVA irradiation, and this increase was inhibited by ecto-nucleotidase or by antagonists of P2Y11 or P2Y13 receptor. These results suggest that UVA-induced IL-6 production is mediated by release of ATP through hemichannels and P2X7 receptor, followed by activation of P2Y11 and P2Y13 receptors. Interestingly, P2Y11 and P2Y13 were associated with the same pattern of IL-6 production, though they trigger different intracellular signaling cascades: Ca2+-dependent and PI3K-dependent, respectively. Thus, IL-6 production in response to UVA-induced ATP release involves at least two distinct pathways, mediated by activation of P2Y11 and P2Y13 receptors.

  15. Neurochemical Changes in the Mouse Hippocampus Underlying the Antidepressant Effect of Genetic Deletion of P2X7 Receptors.

    Science.gov (United States)

    Csölle, Cecilia; Baranyi, Mária; Zsilla, Gabriella; Kittel, Agnes; Gölöncsér, Flóra; Illes, Peter; Papp, Edit; Vizi, E Sylvester; Sperlágh, Beáta

    2013-01-01

    Recent investigations have revealed that the genetic deletion of P2X7 receptors (P2rx7) results in an antidepressant phenotype in mice. However, the link between the deficiency of P2rx7 and changes in behavior has not yet been explored. In the present study, we studied the effect of genetic deletion of P2rx7 on neurochemical changes in the hippocampus that might underlie the antidepressant phenotype. P2X7 receptor deficient mice (P2rx7-/-) displayed decreased immobility in the tail suspension test (TST) and an attenuated anhedonia response in the sucrose preference test (SPT) following bacterial endotoxin (LPS) challenge. The attenuated anhedonia was reproduced through systemic treatments with P2rx7 antagonists. The activation of P2rx7 resulted in the concentration-dependent release of [(3)H]glutamate in P2rx7+/+ but not P2rx7-/- mice, and the NR2B subunit mRNA and protein was upregulated in the hippocampus of P2rx7-/- mice. The brain-derived neurotrophic factor (BDNF) expression was higher in saline but not LPS-treated P2rx7-/- mice; the P2rx7 antagonist Brilliant blue G elevated and the P2rx7 agonist benzoylbenzoyl ATP (BzATP) reduced BDNF level. This effect was dependent on the activation of NMDA and non-NMDA receptors but not on Group I metabotropic glutamate receptors (mGluR1,5). An increased 5-bromo-2-deoxyuridine (BrdU) incorporation was also observed in the dentate gyrus derived from P2rx7-/- mice. Basal level of 5-HT was increased, whereas the 5HIAA/5-HT ratio was lower in the hippocampus of P2rx7-/- mice, which accompanied the increased uptake of [(3)H]5-HT and an elevated number of [(3)H]citalopram binding sites. The LPS-induced elevation of 5-HT level was absent in P2rx7-/- mice. In conclusion there are several potential mechanisms for the antidepressant phenotype of P2rx7-/- mice, such as the absence of P2rx7-mediated glutamate release, elevated basal BDNF production, enhanced neurogenesis and increased 5-HT bioavailability in the hippocampus.

  16. Neurochemical Changes in the Mouse Hippocampus Underlying the Antidepressant Effect of Genetic Deletion of P2X7 Receptors.

    Directory of Open Access Journals (Sweden)

    Cecilia Csölle

    Full Text Available Recent investigations have revealed that the genetic deletion of P2X7 receptors (P2rx7 results in an antidepressant phenotype in mice. However, the link between the deficiency of P2rx7 and changes in behavior has not yet been explored. In the present study, we studied the effect of genetic deletion of P2rx7 on neurochemical changes in the hippocampus that might underlie the antidepressant phenotype. P2X7 receptor deficient mice (P2rx7-/- displayed decreased immobility in the tail suspension test (TST and an attenuated anhedonia response in the sucrose preference test (SPT following bacterial endotoxin (LPS challenge. The attenuated anhedonia was reproduced through systemic treatments with P2rx7 antagonists. The activation of P2rx7 resulted in the concentration-dependent release of [(3H]glutamate in P2rx7+/+ but not P2rx7-/- mice, and the NR2B subunit mRNA and protein was upregulated in the hippocampus of P2rx7-/- mice. The brain-derived neurotrophic factor (BDNF expression was higher in saline but not LPS-treated P2rx7-/- mice; the P2rx7 antagonist Brilliant blue G elevated and the P2rx7 agonist benzoylbenzoyl ATP (BzATP reduced BDNF level. This effect was dependent on the activation of NMDA and non-NMDA receptors but not on Group I metabotropic glutamate receptors (mGluR1,5. An increased 5-bromo-2-deoxyuridine (BrdU incorporation was also observed in the dentate gyrus derived from P2rx7-/- mice. Basal level of 5-HT was increased, whereas the 5HIAA/5-HT ratio was lower in the hippocampus of P2rx7-/- mice, which accompanied the increased uptake of [(3H]5-HT and an elevated number of [(3H]citalopram binding sites. The LPS-induced elevation of 5-HT level was absent in P2rx7-/- mice. In conclusion there are several potential mechanisms for the antidepressant phenotype of P2rx7-/- mice, such as the absence of P2rx7-mediated glutamate release, elevated basal BDNF production, enhanced neurogenesis and increased 5-HT bioavailability in the hippocampus.

  17. $^3P_2$ Superfluids Are Topological

    CERN Document Server

    Mizushima, Takeshi

    2016-01-01

    We clarify the topology of the $^3P_2$ superfluidity which is expected to be realized in the cores of neutron stars and cubic odd-parity superconductors. The phase diagram includes the unitary uniaxial/biaxial nematic phases and nonunitary ferromagnetic and cyclic phases. We here show that the low-energy structures of all the phases are governed by different types of topologically protected gapless fermionic excitations: Surface Majorana fermions in nematic phases, single itinerant Majorana fermion in the ferromagnetic phase, and a quartet of itinerant Majorana fermions in the cyclic phase. Using the superfluid Fermi liquid theory, we also demonstrate that dihedral-two and -four biaxial nematic phases are thermodynamically favored in the weak coupling limit under a magnetic field. The mass acquisition of surface Majorana fermions in nematic phases is subject to symmetry.

  18. Opioid Antagonist Impedes Exposure.

    Science.gov (United States)

    Merluzzi, Thomas V.; And Others

    1991-01-01

    Thirty spider-phobic adults underwent exposure to 17 phobic-related, graded performance tests. Fifteen subjects were assigned to naltrexone, an opioid antagonist, and 15 were assigned to placebo. Naltrexone had a significant effect on exposure, with naltrexone subjects taking significantly longer to complete first 10 steps of exposure and with…

  19. The purinergic P2Y1 receptor supports leptin secretion in adipose tissue.

    Science.gov (United States)

    Laplante, Marc-André; Monassier, Laurent; Freund, Monique; Bousquet, Pascal; Gachet, Christian

    2010-05-01

    Extracellular nucleotides have been shown to trigger intracellular calcium release and influence leptin secretion in differentiated white and brown adipocytes through activation of various but not clearly identified P2 receptors. In the present study, we wished to assess whether or not the P2Y1 ADP receptor is functional in white adipocytes and whether it could affect the secretion of adipocyte-derived hormones. Stromal cells and mature adipocytes were isolated from epididymal adipose tissue from wild-type and P2Y1 knockout (KO) C57-black/six male mice. The expression of the P2Y1 receptor in adipocytes was confirmed by RT-PCR and intracellular calcium measurements with fura 2-AM. KO of P2Y1 receptors did not affect the cell size and lipid content of mature adipocytes or the differentiation of the stromal cell fraction, but the leptin production of mature adipocytes was decreased under basal and insulin-stimulated conditions. A selective P2Y1 antagonist, MRS2500, reduced leptin release in isolated adipocytes. The plasma and adipose tissue mRNA levels of leptin were also lower in P2Y1 KO mice as compared with wild-type animals. However, in mice fed a high-fat diet, the plasma leptin levels were greatly enhanced and the inhibitory effect of P2Y1 KO was not observed. These results show that the P2Y1 receptor supports leptin production in isolated white adipocytes through a transcriptional mechanism. This function of the receptor may regulate plasma leptin in lean mice but is overcome in obese animals.

  20. P2X7 receptor activation regulates rapid unconventional export of transglutaminase-2.

    Science.gov (United States)

    Adamczyk, Magdalena; Griffiths, Rhiannon; Dewitt, Sharon; Knäuper, Vera; Aeschlimann, Daniel

    2015-12-15

    Transglutaminases (denoted TG or TGM) are externalized from cells via an unknown unconventional secretory pathway. Here, we show for the first time that purinergic signaling regulates active secretion of TG2 (also known as TGM2), an enzyme with a pivotal role in stabilizing extracellular matrices and modulating cell-matrix interactions in tissue repair. Extracellular ATP promotes TG2 secretion by macrophages, and this can be blocked by a selective antagonist against the purinergic receptor P2X7 (P2X7R, also known as P2RX7). Introduction of functional P2X7R into HEK293 cells is sufficient to confer rapid, regulated TG2 export. By employing pharmacological agents, TG2 release could be separated from P2X7R-mediated microvesicle shedding. Neither Ca(2+) signaling alone nor membrane depolarization triggered TG2 secretion, which occurred only upon receptor membrane pore formation and without pannexin channel involvement. A gain-of-function mutation in P2X7R associated with autoimmune disease caused enhanced TG2 externalization from cells, and this correlated with increased pore activity. These results provide a mechanistic explanation for a link between active TG2 secretion and inflammatory responses, and aberrant enhanced TG2 activity in certain autoimmune conditions.

  1. P2X7 receptors induce degranulation in human mast cells.

    Science.gov (United States)

    Wareham, Kathryn J; Seward, Elizabeth P

    2016-06-01

    Mast cells play important roles in host defence against pathogens, as well as being a key effector cell in diseases with an allergic basis such as asthma and an increasing list of other chronic inflammatory conditions. Mast cells initiate immune responses through the release of newly synthesised eicosanoids and the secretion of pre-formed mediators such as histamine which they store in specialised granules. Calcium plays a key role in regulating both the synthesis and secretion of mast-cell-derived mediators, with influx across the membrane, in particular, being necessary for degranulation. This raises the possibility that calcium influx through P2X receptors may lead to antigen-independent secretion of histamine and other granule-derived mediators from human mast cells. Here we show that activation of P2X7 receptors with both ATP and BzATP induces robust calcium rises in human mast cells and triggers their degranulation; both effects are blocked by the P2X7 antagonist AZ11645373, or the removal of calcium from the extracellular medium. Activation of P2X1 receptors with αβmeATP also induces calcium influx in human mast cells, which is significantly reduced by both PPADS and NF 449. P2X1 receptor activation, however, does not trigger degranulation. The results indicate that P2X7 receptors may play a significant role in contributing to the unwanted activation of mast cells in chronic inflammatory conditions where extracellular ATP levels are elevated.

  2. Activation of P2X7 receptors decreases the proliferation of murine luteal cells.

    Science.gov (United States)

    Wang, Jing; Liu, Shuangmei; Nie, Yijun; Wu, Bing; Wu, Qin; Song, Miaomiao; Tang, Min; Xiao, Li; Xu, Ping; Tan, Ximin; Zhang, Luyin; Li, Gang; Liang, Shangdong; Zhang, Chunping

    2015-11-01

    Extracellular ATP regulates cellular function in an autocrine or paracrine manner through activating purinergic signalling. Studies have shown that purinergic receptors were expressed in mammalian ovaries and they have been proposed as an intra-ovarian regulatory mechanism. P2X7 was expressed in porcine ovarian theca cells and murine and human ovarian surface epithelium and is involved in ATP-induced apoptotic cell death. However, the role of P2X7 in corpus luteum is still unclear. The aim of this study was to investigate the role of ATP signalling in murine luteal cells and the possible mechanism(s) involved. We found that P2X7 was highly expressed in murine small luteal cells. The agonists of P2X7, ATP and BzATP, inhibited the proliferation of luteal cells. P2X7 antagonist BBG reversed the inhibition induced by ATP and BzATP. Further studies showed that ATP and BzATP inhibited the expression of cell cycle regulators cyclinD2 and cyclinE2. ATP and BzATP also inhibited the p38-mitogen-activated protein kinase (MAPK) signalling pathway. These results reveal that P2X7 receptor activation is involved in corpus luteum formation and function.

  3. Mouse Leydig cells express multiple P2X receptor subunits

    OpenAIRE

    2008-01-01

    ATP acts on cellular membranes by interacting with P2X (ionotropic) and P2Y (metabotropic) receptors. Seven homomeric P2X receptors (P2X1–P2X7) and seven heteromeric receptors (P2X1/2, P2X1/4, P2X1/5, P2X2/3, P2X2/6, P2X4/6, P2X4/7) have been described. ATP treatment of Leydig cells leads to an increase in [Ca2+]i and testosterone secretion, supporting the hypothesis that Ca2+ signaling through purinergic receptors contributes to the process of testosterone secretion in these cells. Mouse Ley...

  4. P2PRPIPS: A P2P and Reverse Proxy Based Web Intrusion Protection System

    Directory of Open Access Journals (Sweden)

    Qian He

    2013-03-01

    Full Text Available In order to protect web sites with various program languages and high throughput efficiently, a web Intrusion Protection System (IPS based on P2P and reverse proxy architecture was designed and implemented. The P2P based web intrusion protection system has multi web firewall nodes and nodes with same program cooperate with each other under P2P architecture. Some nodes work as net flow allocator and some work as detector and they can convert to each other according to the requirements dynamically. The WAF program has the characteristics of session keeping and load balancing and it can detect messages by using expert library and many plug-in components. The technology of reverse proxy is used for response the web request. Experiments show that the system can effectively prevent attacks form application layer. It is proved more efficient and stable than single node.

  5. Localized Multistreams for P2P Streaming

    Directory of Open Access Journals (Sweden)

    Majed Alhaisoni

    2010-01-01

    Full Text Available Streaming video over the Internet, including cellular networks, has now become a commonplace. Network operators typically use multicasting or variants of multiple unicasting to deliver streams to the user terminal in a controlled fashion. P2P streaming is an emerging alternative, which is theoretically more scalable but suffers from other issues arising from the dynamic nature of the system. Users' terminals become streaming nodes but they are not constantly connected. Another issue is that they are based on logical overlays, which are not optimized for the physical underlay infrastructure. An important proposition is to find effective ways to increase the resilience of the overlay whilst at the same time not conflicting with the network. In this article we look at the combination of two techniques, redundant streaming and locality awareness, in the context of both live and video-on-demand streaming. We introduce a new technique and assess it via a comparative, simulation-based study. We find that redundancy affects network utilization only marginally if traffic is kept at the edges via localization techniques.

  6. The ViP2P Platform: XML Views in P2P

    CERN Document Server

    Karanasos, Konstantinos; Manolescu, Ioana; Zoupanos, Spyros

    2011-01-01

    The growing volumes of XML data sources on the Web or produced by enterprises, organizations etc. raise many performance challenges for data management applications. In this work, we are concerned with the distributed, peer-to-peer management of large corpora of XML documents, based on distributed hash table (or DHT, in short) overlay networks. We present ViP2P (standing for Views in Peer-to-Peer), a distributed platform for sharing XML documents based on a structured P2P network infrastructure (DHT). At the core of ViP2P stand distributed materialized XML views, defined by arbitrary XML queries, filled in with data published anywhere in the network, and exploited to efficiently answer queries issued by any network peer. ViP2P allows user queries to be evaluated over XML documents published by peers in two modes. First, a long-running subscription mode, when a query can be registered in the system and receive answers incrementally when and if published data matches the query. Second, queries can also be asked...

  7. P2X7 receptors on osteoblasts couple to production of lysophosphatidic acid: a signaling axis promoting osteogenesis.

    Science.gov (United States)

    Panupinthu, Nattapon; Rogers, Joseph T; Zhao, Lin; Solano-Flores, Luis Pastor; Possmayer, Fred; Sims, Stephen M; Dixon, S Jeffrey

    2008-06-02

    Nucleotides are released from cells in response to mechanical stimuli and signal in an autocrine/paracrine manner through cell surface P2 receptors. P2rx7-/- mice exhibit diminished appositional growth of long bones and impaired responses to mechanical loading. We find that calvarial sutures are wider in P2rx7-/- mice. Functional P2X7 receptors are expressed on osteoblasts in situ and in vitro. Activation of P2X7 receptors by exogenous nucleotides stimulates expression of osteoblast markers and enhances mineralization in cultures of rat calvarial cells. Moreover, osteogenesis is suppressed in calvarial cell cultures from P2rx7-/- mice compared with the wild type. P2X7 receptors couple to production of the potent lipid mediators lysophosphatidic acid (LPA) and prostaglandin E2. Either an LPA receptor antagonist or cyclooxygenase (COX) inhibitors abolish the stimulatory effects of P2X7 receptor activation on osteogenesis. We conclude that P2X7 receptors enhance osteoblast function through a cell-autonomous mechanism. Furthermore, a novel signaling axis links P2X7 receptors to production of LPA and COX metabolites, which in turn stimulate osteogenesis.

  8. ERK1/2 activation is involved in the neuroprotective action of P2Y13 and P2X7 receptors against glutamate excitotoxicity in cerebellar granule neurons.

    Science.gov (United States)

    Ortega, Felipe; Pérez-Sen, Raquel; Delicado, Esmerilda G; Teresa Miras-Portugal, M

    2011-12-01

    Cerebellar granule neurons express several types of nucleotide receptors, with the metabotropic P2Y(13) and the ionotropic P2X7 being the most relevant in this model. In the present study we investigated the role of P2Y(13) and P2X7 nucleotide receptors in ERK1/2 signalling. The nucleotidic agonists 2MeSADP (2-methylthioadenosine-5'-diphosphate) for P2Y(13) and BzATP (2'(3')-O-(4-benzoylbenzoyl)adenosine-5'-triphosphate) for P2X7 receptors were coupled to ERK1/2 activation in granule neurons, being able to increase around two-fold the levels of ERK1/2 phosphorylation. These effects were sensitive to the inhibitory action of the antagonists MRS-2211 and A-438079, specific for P2Y(13) and P2X7 receptors, respectively. Although both receptor subtypes shared the same pattern of transient ERK1/2 phosphorylation, they differed in the intracellular cascades they triggered, being PI3K-dependent for P2Y(13) and calcium/calmodulin kinase II (CaMKII)-dependent for P2X7. These two different ERK-mediated pathways were involved in the neuroprotective effects displayed by both P2Y(13) and P2X7 receptors against apoptosis induced by an excitotoxic concentration of glutamate, in a similar manner to the neurotrophin, BDNF. In addition, P2Y(13) and P2X7 receptor agonists were also able to phosphorylate and activate the ERK-dependent target CREB, which could be involved in their neuroprotective effect. These results indicate that nucleotide receptors share with trophic factors the same survival routes in neurons, such as the ERK signalling route, and therefore, can contribute to the maintenance of granule neurons in conditions in which survival is being compromised.

  9. P2X7 receptors at adult neural progenitor cells of the mouse subventricular zone.

    Science.gov (United States)

    Messemer, Nanette; Kunert, Christin; Grohmann, Marcus; Sobottka, Helga; Nieber, Karen; Zimmermann, Herbert; Franke, Heike; Nörenberg, Wolfgang; Straub, Isabelle; Schaefer, Michael; Riedel, Thomas; Illes, Peter; Rubini, Patrizia

    2013-10-01

    Neurogenesis requires the balance between the proliferation of newly formed progenitor cells and subsequent death of surplus cells. RT-PCR and immunocytochemistry demonstrated the presence of P2X7 receptor mRNA and immunoreactivity in cultured neural progenitor cells (NPCs) prepared from the adult mouse subventricular zone (SVZ). Whole-cell patch-clamp recordings showed a marked potentiation of the inward current responses both to ATP and the prototypic P2X7 receptor agonist dibenzoyl-ATP (Bz-ATP) at low Ca(2+) and zero Mg(2+) concentrations in the bath medium. The Bz-ATP-induced currents reversed their polarity near 0 mV; in NPCs prepared from P2X7(-/-) mice, Bz-ATP failed to elicit membrane currents. The general P2X/P2Y receptor antagonist PPADS and the P2X7 selective antagonists Brilliant Blue G and A-438079 strongly depressed the effect of Bz-ATP. Long-lasting application of Bz-ATP induced an initial current, which slowly increased to a steady-state response. In combination with the determination of YO-PRO uptake, these experiments suggest the dilation of a receptor-channel and/or the recruitment of a dye-uptake pathway. Ca(2+)-imaging by means of Fura-2 revealed that in a Mg(2+)-deficient bath medium Bz-ATP causes [Ca(2+)](i) transients fully depending on the presence of external Ca(2+). The MTT test indicated a concentration-dependent decrease in cell viability by Bz-ATP treatment. Correspondingly, Bz-ATP led to an increase in active caspase 3 immunoreactivity, indicating a P2X7-controlled apoptosis. In acute SVZ brain slices of transgenic Tg(nestin/EGFP) mice, patch-clamp recordings identified P2X7 receptors at NPCs with pharmacological properties identical to those of their cultured counterparts. We suggest that the apoptotic/necrotic P2X7 receptors at NPCs may be of particular relevance during pathological conditions which lead to increased ATP release and thus could counterbalance the ensuing excessive cell proliferation.

  10. Calcium antagonists and vasospasm.

    Science.gov (United States)

    Meyer, F B

    1990-04-01

    A critical review of the clinical data supports the conclusion that nimodipine decreases the severity of neurologic deficits and improves outcome after subarachnoid hemorrhage. The mechanisms by which mortality and morbidity are reduced are still controversial. First, the frequency of vasospasm is not altered (Figs. 5 and 6). Second, the consistent reversal of vasospasm once present has not been demonstrated either angiographically or by noninvasive cerebral blood flow studies. These observations suggest that there is either modification of microcirculatory flow (i.e., dilation of pial conducting vessels or decreased platelet aggregation) or a direct neuronal protective effect. As suggested previously, support for either mechanism is not resolute, and further investigation is necessary. Currently, nimodipine has been the most thoroughly investigated calcium antagonist both from an experimental and clinical perspective. Oral administration has had few reported complications. Therefore, the benefit/risk ratio clearly supports the prophylactic use of this calcium antagonist in patients of all clinical grades after subarachnoid hemorrhage. Evidence also indicates that starting nimodipine after the onset of delayed ischemic deficits is of benefit. Finally, it can be predicted that in the future additional calcium antagonists with more selective vascular or neuronal effects will be developed for use in neurologic disorders.

  11. Validation of a P2Y12-receptor specific whole blood platelet aggregation assay.

    Science.gov (United States)

    Amann, Michael; Ferenc, Miroslaw; Valina, Christian M; Bömicke, Timo; Stratz, Christian; Leggewie, Stefan; Trenk, Dietmar; Neumann, Franz-Josef; Hochholzer, Willibald

    2016-11-01

    Testing of P2Y12-receptor antagonist effects can support clinical decision-making. However, most platelet function assays use only ADP as agonist which is not P2Y12-receptor specific. For this reason P2Y12-receptor specific assays have been developed by adding prostaglandin E1 (PGE1) to reduce ADP-induced platelet activation via the P2Y1-receptor. The present study sought to evaluate a P2Y12-receptor specific assay for determination of pharmacodynamic and clinical outcomes. This study enrolled 400 patients undergoing coronary stenting after loading with clopidogrel or prasugrel. ADP-induced platelet reactivity was assessed by whole blood aggregometry at multiple time points with a standard ADP assay (ADPtest) and a P2Y12-receptor specific assay (ADPtest HS, both run on Multiplate Analyzer, Roche Diagnostics). Patients were clinically followed for 1 month and all events adjudicated by an independent committee. In total, 2084 pairs of test results of ADPtest and ADPtest HS were available showing a strong correlation between results of both assays (r = 0.96, p < 0.001). These findings prevailed in multiple prespecified subgroups (e.g., age; body mass index; diabetes). Calculated cutoffs for ADPtest HS and the established cutoffs of ADPtest showed a substantial agreement for prediction of ischemic and hemorrhagic events with a Cohen's κ of 0.66 and 0.66, respectively. The P2Y12-receptor specific ADPtest HS assay appears similarly predictive for pharmacodynamic and clinical outcomes as compared to the established ADPtest assay indicating its applicability for clinical use. Further evaluation in large cohorts is needed to determine if P2Y12-receptor specific testing offers any advantage for prediction of clinical outcome.

  12. P2X7 receptors mediate resistance to toxin-induced cell lysis.

    Science.gov (United States)

    Schoenauer, Roman; Atanassoff, Alexander P; Wolfmeier, Heidi; Pelegrin, Pablo; Babiychuk, Eduard B; Draeger, Annette

    2014-05-01

    In the majority of cells, the integrity of the plasmalemma is recurrently compromised by mechanical or chemical stress. Serum complement or bacterial pore-forming toxins can perforate the plasma membrane provoking uncontrolled Ca(2+) influx, loss of cytoplasmic constituents and cell lysis. Plasmalemmal blebbing has previously been shown to protect cells against bacterial pore-forming toxins. The activation of the P2X7 receptor (P2X7R), an ATP-gated trimeric membrane cation channel, triggers Ca(2+) influx and induces blebbing. We have investigated the role of the P2X7R as a regulator of plasmalemmal protection after toxin-induced membrane perforation caused by bacterial streptolysin O (SLO). Our results show that the expression and activation of the P2X7R furnishes cells with an increased chance of surviving attacks by SLO. This protective effect can be demonstrated not only in human embryonic kidney 293 (HEK) cells transfected with the P2X7R, but also in human mast cells (HMC-1), which express the receptor endogenously. In addition, this effect is abolished by treatment with blebbistatin or A-438079, a selective P2X7R antagonist. Thus blebbing, which is elicited by the ATP-mediated, paracrine activation of the P2X7R, is part of a cellular non-immune defense mechanism. It pre-empts plasmalemmal damage and promotes cellular survival. This mechanism is of considerable importance for cells of the immune system which carry the P2X7R and which are specifically exposed to toxin attacks.

  13. The P2X7 receptor is an important regulator of extracellular ATP levels

    Directory of Open Access Journals (Sweden)

    Andrea eBrandao-Burch

    2012-03-01

    Full Text Available Controlled ATP release has been demonstrated from many neuronal and non-neuronal cell types. Once released, extracellular ATP acts on cells in a paracrine manner via purinergic receptors. Considerable evidence now suggests that extracellular nucleotides, signalling via P2 receptors, play important roles in bone homeostasis modulating both osteoblast and osteoclast function. In this study, we demonstrate that mouse osteoclasts and their precursors constitutively release ATP into their extracellular environment. Levels were highest at day 2 (precursor cells, possibly reflecting the high number of red blood cells and accessory cells present. Mature osteoclasts constitutively released ATP in the range 0.05-0.5pmol/ml/cell. Both osteoclasts and osteoblasts express mRNA and protein for the P2X7 receptor. We found that in osteoclasts, expression levels are 4-fold higher in mature cells relative to precursors, whilst in osteoblasts expression remains relatively constant during differentiation. Selective antagonists (0.1-100µM AZ10606120, A438079 and KN-62 were used to determine whether this release was mediated via P2X7 receptors. AZ10606120, A438079 and KN-62, at 0.1-10µM, decreased ATP release by mature osteoclasts by up to 70%, 60% and 80%, respectively. No differences in cell viability were observed. ATP release also occurs via vesicular exocytosis; inhibitors of this process (1-100µM NEM or brefeldin A had no effect on ATP release from osteoclasts. P2X7 receptor antagonists (0.1-10µM also decreased ATP release from primary rat osteoblasts by up to 80%. These data show that ATP release via the P2X7 receptor contributes to extracellular ATP levels in osteoclast and osteoblast cultures, suggesting an important additional role for this receptor in autocrine/paracrine purinergic signalling in bone.

  14. Sensing arterial CO(2) levels: a role for medullary P2X receptors.

    Science.gov (United States)

    Spyer, K M; Thomas, T

    2000-07-01

    ATP has been shown to act as an excitatory neurotransmitter in the central nervous system. In this review, evidence is presented to indicate that when ATP is micro-injected into the ventrolateral medulla (VLM) of the rat, changes in respiratory activity are elicited. These effects, and accompanying changes in heart rate and blood pressure are mediated by P2X purinoreceptors. Immunocytochemistry indicates a prevalence of P2X(2) and P2X(6) purinoreceptors in this region of the medulla. The P2 purinoceptor antagonists, suramin and PPADS blunt the respiratory responses to changes in arterial CO(2) levels when micro-injected into the VLM. This effect is shown electrophysiologically to be mediated by purinoreceptors located primarily on respiratory neurones of the VLM including the Bötzinger complex. As the effects of agonist activation of P2X(2) purinoceptors expressed in HEK293 cells and Xenopus oocytes are potentiated by lowering pH, these data imply that the central respiratory response to CO(2) depends in part on the pH sensitivity of purinoreceptors located on inspiratory neurones. The implications for respiratory activity and control are discussed.

  15. Peripheral mechanisms underlying the essential role of P2X7 receptors in the development of inflammatory hyperalgesia.

    Science.gov (United States)

    Teixeira, Juliana Maia; Oliveira, Maria Cláudia G; Parada, Carlos Amílcar; Tambeli, Cláudia Herrera

    2010-10-10

    Activation of P2X7 receptors by endogenous ATP contributes to the development of inflammatory hyperalgesia. Given the clinical importance of mechanical hyperalgesia in inflammatory states, we hypothesized that the activation of the P2X7 receptor by endogenous ATP contributes to carrageenan-induced mechanical hyperalgesia, and that this contribution is mediated by an indirect sensitization of the primary afferent nociceptors. Co-administration of the selective P2X7 receptor antagonist, A-438079, or the P2X7 receptor antagonist, oATP, with carrageenan blocked the mechanical hyperalgesia induced by carrageenan and significantly reduced the increased concentration of TNF-alpha, IL-6 and CINC-1, but not of IL-1beta induced by carrageenan in the subcutaneous tissue of the rat's hind paw. We concluded that the activation of P2X7 receptors by endogenous ATP is essential to the development of the mechanical hyperalgesia induced by carrageenan in the subcutaneous tissue. It is suggested that this essential role of P2X7 receptors in the development of carrageenan-induced mechanical hyperalgesia is mediated by an indirect sensitization of the primary afferent nociceptors dependent on the previous release of TNF-alpha, IL-6 and CINC-1, but not of IL-1beta.

  16. Tetrahydroindolizinone NK1 antagonists.

    Science.gov (United States)

    Bao, Jianming; Lu, Huagang; Morriello, Gregori J; Carlson, Emma J; Wheeldon, Alan; Chicchi, Gary G; Kurtz, Marc M; Tsao, Kwei-Lan C; Zheng, Song; Tong, Xinchun; Mills, Sander G; DeVita, Robert J

    2010-04-01

    A new class of potent NK(1) receptor antagonists with a tetrahydroindolizinone core has been identified. This series of compounds demonstrated improved functional activities as compared to previously identified 5,5-fused pyrrolidine lead structures. SAR at the 7-position of the tetrahydroindolizinone core is discussed in detail. A number of compounds displayed high NK(1) receptor occupancy at both 1 h and 24 h in a gerbil foot tapping model. Compound 40 has high NK(1) binding affinity, good selectivity for other NK receptors and promising in vivo properties. It also has clean P(450) inhibition and hPXR induction profiles.

  17. The discovery and development of P2 receptor subtypes.

    Science.gov (United States)

    Kennedy, C

    2000-07-01

    Extracellular purine and pyrimidine nucleotides modulate cellular activity by acting at P2 receptors. The first receptor to be identified was the P(2)-purinoceptor, which was characterised and named in 1978. In the 1980s this site was subdivided into P(2X) and P(2Y) purinoceptors on the basis of pharmacological criteria in functional studies on native receptors. Subsequently, a similar approach led to the characterisation of the P(2T), P(2Z), P(2U) and P(2D) purinoceptors. In the 1990s a molecular biological approach has led to the cloning and functional expression of at least 12 mammalian P2 receptor subtypes. The challenge now is to relate these recombinant receptors to native receptors present within a wide range of tissues.

  18. Interaction of medullary P2 and glutamate receptors mediates the vasodilation in the hindlimb of rat.

    Science.gov (United States)

    Korim, Willian Seiji; Ferreira-Neto, Marcos L; Pedrino, Gustavo R; Pilowsky, Paul M; Cravo, Sergio L

    2012-12-01

    In the nucleus tractus solitarii (NTS) of rats, blockade of extracellular ATP breakdown to adenosine reduces arterial blood pressure (AP) increases that follow stimulation of the hypothalamic defense area (HDA). The effects of ATP on NTS P2 receptors, during stimulation of the HDA, are still unclear. The aim of this study was to determine whether activation of P2 receptors in the NTS mediates cardiovascular responses to HDA stimulation. Further investigation was taken to establish if changes in hindlimb vascular conductance (HVC) elicited by electrical stimulation of the HDA, or activation of P2 receptors in the NTS, are relayed in the rostral ventrolateral medulla (RVLM); and if those responses depend on glutamate release by ATP acting on presynaptic terminals. In anesthetized and paralyzed rats, electrical stimulation of the HDA increased AP and HVC. Blockade of P2 or glutamate receptors in the NTS, with bilateral microinjections of suramin (10 mM) or kynurenate (50 mM) reduced only the evoked increase in HVC by 75 % or more. Similar results were obtained with the blockade combining both antagonists. Blockade of P2 and glutamate receptors in the RVLM also reduced the increases in HVC to stimulation of the HDA by up to 75 %. Bilateral microinjections of kynurenate in the RVLM abolished changes in AP and HVC to injections of the P2 receptor agonist α,β-methylene ATP (20 mM) into the NTS. The findings suggest that HDA-NTS-RVLM pathways in control of HVC are mediated by activation of P2 and glutamate receptors in the brainstem in alerting-defense reactions.

  19. P2X receptor-mediated ATP purinergic signaling in health and disease

    Directory of Open Access Journals (Sweden)

    Jiang LH

    2012-09-01

    Full Text Available Lin-Hua JiangSchool of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United KingdomAbstract: Purinergic P2X receptors are plasma membrane proteins present in a wide range of mammalian cells where they act as a cellular sensor, enabling cells to detect and respond to extracellular adenosine triphosphate (ATP, an important signaling molecule. P2X receptors function as ligand-gated Ca2+-permeable cationic channels that open upon ATP binding to elevate intracellular Ca2+ concentrations and cause membrane depolarization. In response to sustained activation, P2X receptors induce formation of a pore permeable to large molecules. P2X receptors also interact with distinct functional proteins and membrane lipids to form specialized signaling complexes. Studies have provided compelling evidence to show that such P2X receptor-mediated ATP-signaling mechanisms determine and regulate a growing number and diversity of important physiological processes, including neurotransmission, muscle contraction, and cytokine release. There is accumulating evidence to support strong causative relationships of altered receptor expression and function with chronic pain, inflammatory diseases, cancers, and other pathologies or diseases. Numerous high throughput screening drug discovery programs and preclinical studies have thus far demonstrated the proof of concepts that the P2X receptors are druggable targets and selective receptor antagonism is a promising therapeutics approach. This review will discuss the recent progress in understanding the mammalian P2X receptors with respect to the ATP-signaling mechanisms, physiological and pathophysiological roles, and development and preclinical studies of receptor antagonists.Keywords: extracellular ATP, ion channel, large pore, signaling complex, chronic pain, inflammatory diseases

  20. Pharmacological characterization of the P2 receptors profile in the podocytes of the freshly isolated rat glomeruli.

    Science.gov (United States)

    Ilatovskaya, Daria V; Palygin, Oleg; Levchenko, Vladislav; Staruschenko, Alexander

    2013-11-15

    Calcium flux in the podocytes is critical for normal and pathophysiological regulation of these types of cells, and excessive calcium signaling results in podocytes damage and improper glomeruli function. Purinergic activation of P2 receptors is a powerful and rapid signaling process; however, the exact physiological identity of P2 receptors subtypes in podocytes remains essentially unknown. The goal of this study was to determine the P2 receptor profile in podocytes of the intact Sprague-Dawley rat glomeruli using available pharmacological tools. Glomeruli were isolated by differential sieving and loaded with Fluo-4/Fura Red cell permeable calcium indicators, and the purinergic response in the podocytes was analyzed with ratiometric confocal fluorescence measurements. Various P2 receptors activators were tested and compared with the effect of ATP, specifically, UDP, MRS 2365, bzATP, αβ-methylene, 2-meSADP, MRS 4062, and MRS 2768, were analyzed. Antagonists (MRS 2500, 5-BDBD, A438079, and NF 449) were tested when 10 μM ATP was applied as the EC50 for ATP activation of the calcium influx in the podocytes was determined to be 10.7 ± 1.5 μM. Several agonists including MRS 2365 and 2-meSADP caused calcium flux. Importantly, only the P2Y1-specific antagonist MRS 2500 (1 nM) precluded the effects of ATP concentrations of the physiological range. Immunohistochemical analysis confirmed that P2Y1 receptors are highly expressed in the podocytes. We conclude that P2Y1 receptor signaling is the predominant P2Y purinergic pathway in the glomeruli podocytes and P2Y1 might be involved in the pathogenesis of glomerular injury and could be a target for treatment of kidney diseases.

  1. P2X7 receptor-mediated purinergic signaling promotes liver injury in acetaminophen hepatotoxicity in mice.

    Science.gov (United States)

    Hoque, Rafaz; Sohail, Muhammed Adnan; Salhanick, Steven; Malik, Ahsan F; Ghani, Ayaz; Robson, Simon C; Mehal, Wajahat Z

    2012-05-15

    Inflammation contributes to liver injury in acetaminophen (APAP) hepatotoxicity in mice and is triggered by stimulation of immune cells. The purinergic receptor P2X7 is upstream of the nod-like receptor family, pryin domain containing-3 (NLRP3) inflammasome in immune cells and is activated by ATP and NAD that serve as damage-associated molecular patterns. APAP hepatotoxicity was assessed in mice genetically deficient in P2X7, the key inflammatory receptor for nucleotides (P2X7-/-), and in wild-type mice. P2X7-/- mice had significantly decreased APAP-induced liver necrosis. In addition, APAP-poisoned mice were treated with the specific P2X7 antagonist A438079 or etheno-NAD, a competitive antagonist of NAD. Pre- or posttreatment with A438079 significantly decreased APAP-induced necrosis and hemorrhage in APAP liver injury in wild-type but not P2X7-/- mice. Pretreatment with etheno-NAD also significantly decreased APAP-induced necrosis and hemorrhage in APAP liver injury. In addition, APAP toxicity in mice lacking the plasma membrane ecto-NTPDase CD39 (CD39-/-) that metabolizes ATP was examined in parallel with the use of soluble apyrase to deplete extracellular ATP in wild-type mice. CD39-/- mice had increased APAP-induced hemorrhage and mortality, whereas apyrase also decreased APAP-induced mortality. Kupffer cells were treated with extracellular ATP to assess P2X7-dependent inflammasome activation. P2X7 was required for ATP-stimulated IL-1β release. In conclusion, P2X7 and exposure to the ligands ATP and NAD are required for manifestations of APAP-induced hepatotoxicity.

  2. P2X7 receptors contribute to the currents induced by ATP in guinea pig intestinal myenteric neurons.

    Science.gov (United States)

    Valdez-Morales, Eduardo; Guerrero-Alba, Raquel; Liñán-Rico, Andrómeda; Espinosa-Luna, Rosa; Zarazua-Guzman, Sergio; Miranda-Morales, Marcela; Montaño, Luis M; Barajas-López, Carlos

    2011-10-15

    The whole-cell configuration, several pharmacological tools, and single-cell RT-PCR were used to investigate the contribution of P2X7 subunits to the ATP-induced currents (I(ATP)) in guinea pig myenteric neurons. I(ATP) was recorded in the great majority of tested neurons. ATP concentration-response curve (0.01-10mM) showed two phases, the first mediated by high-sensitive P2X receptors (hsP2X receptors), observed between 0.01-0.3mM and the second mediated by low-sensitive P2X receptors (lsP2X receptors). The calculated EC(50) values of these phases were 38 and 1759 μM, respectively. 2'-3'-O-(4-benzoylbenzoyl)-ATP (BzATP) concentration-response curve was monophasic (0.01-1mM), and less potent (EC(50) 142 μM) than ATP to activate hsP2X receptors. A strong inward rectification was noticed when hsP2X receptors were activated with ATP (0.1mM) and for BzATP-induced currents (0.1mM; I(BzATP)) but a significant lower rectification was noticed when lsP2X receptors were activated (5mM). Brilliant blue G (BBG) at a concentration of 0.3 μM (known to inhibit only P2X7 receptors) reduced I(ATP) when lsP2X receptors contributed to it but neither affect hsP2X receptors nor I(BzATP). However, hsP2X receptors and I(BzATP) were both inhibited by concentrations ≥ 1 μM of this antagonist. BzATP inhibited hsP2X receptors and therefore, it behaves as partial agonist on these receptors. Using the single-cell RT-PCR technique P2X7 mRNA was detectable in 7 out of 13 myenteric neurons exhibiting P2X2 mRNA. Altogether, our results show that low-sensitive P2X receptors are likely P2X7, whereas, the high-sensitive P2X channels are probably constituted, at least in part, by P2X2 subunits.

  3. On the {P2, P3}-Factor of Cubic Graphs

    Institute of Scientific and Technical Information of China (English)

    GOU Kui-xiang; SUN Liang

    2005-01-01

    Let G = ( V, E) be a finite simple graph and Pn denote the path of order n. A spanning subgraph F is called a {P2, P3}-factor of G if each component of F is isomorphic to P2 or P3. With the path-covering method, it is proved that any connected cubic graph with at least 5 vertices has a { P2, P3 }-factor F such that | P3 (F) |≥|P2 (F) |, where P2 (F) and P3 (F) denote the set of components of P2 and P3 in F,respectively.

  4. Bone phenotypes of P2 receptor knockout mice

    DEFF Research Database (Denmark)

    Orriss, Isabel; Syberg, Susanne; Wang, Ning

    2011-01-01

    been observed in an impressive number of these mice: distinct abnormalities in P2X7-/- mice, depending on the gene targeting construct and the genetic background, decreased bone mass in P2Y1-/- mice, increased bone mass in P2Y2-/- mice, decreased bone resorption in P2Y6-/- mice, decreased bone...... formation and bone resorption in P2Y13-/- mice. These findings demonstrate the unexpected importance of extracellular nucleotide signalling in the regulation of bone metabolism via multiple P2 receptors and distinct mechanisms involving both osteoblasts and osteoclasts....

  5. HIGH AFFINITY ACYLATING ANTAGONISTS FOR MUSCARINIC RECEPTORS

    Science.gov (United States)

    Baumgold, Jesse; Karton, Yishai; Malka, Naftali; Jacobson, Kenneth A.

    2012-01-01

    Summary The muscarinic antagonists pirenzepine and telenzepine were derivitized as alkylamino derivatives at a site on the molecules corresponding to a region of bulk tolerance in receptor binding. The distal primary amino groups were coupled to the cross-linking reagent meta-phenylene diisothiocyanate, resulting in two isothiocyanate derivatives that were found to inhibit muscarinic receptors irreversibly and in a dose-dependent fashion. Preincubation of rat forebrain membranes with an isothiocyanate derivative followed by radioligand binding using [3H]N-methylscopolamine diminished the Bmax value, but did not affect the Kd value. The receptor binding site was not restored upon repeated washing, indicating that irreversible inhibition had occurred. IC50 values for the irreversible inhibition at rat forebrain muscarinic receptors were 0.15 nM and 0.19 nM, for derivatives of pirenzepine and telenzepine, respectively. The isothiocyanate derivative of pirenzepine was non-selective as an irreversible muscarinic inhibitor, and the corresponding derivative prepared from telenzepine was 5-fold selective for forebrain (mainly m1) vs. heart (m2) muscarinic receptors. PMID:1625525

  6. Differential expression of porins OmpP2A and OmpP2B of Haemophilus ducreyi.

    Science.gov (United States)

    Prather, Derrick T; Bains, Manjeet; Hancock, Robert E W; Filiatrault, Melanie J; Campagnari, Anthony A

    2004-11-01

    Haemophilus ducreyi is a strict human pathogen and the causative agent of the sexually transmitted disease chancroid. The genome of the human-passaged strain of H. ducreyi (35000HP) contains two homologous genes whose protein products have estimated molecular masses of 46 and 43 kDa. A comparative analysis of the deduced amino acid sequences revealed that these proteins share 27 to 33% identity to the outer membrane protein P2 (OmpP2), a major porin of Haemophilus influenzae. Therefore, these proteins have been designated OmpP2A and OmpP2B, respectively. The detection of ompP2A and ompP2B transcripts by reverse transcriptase PCR indicated that these genes were independently transcribed in H. ducreyi 35000HP. Western blot analysis of outer membrane proteins isolated from a geographically diverse collection of H. ducreyi clinical isolates revealed that OmpP2A and OmpP2B were differentially expressed among these strains. Although PCR analysis suggested that ompP2A and ompP2B were conserved among the strains tested, the differential expression observed was due to nucleotide additions and partial gene deletions. Purified OmpP2A and OmpP2B were isolated under nondenaturing conditions, and subsequent analysis demonstrated that these two proteins exhibited porin activity. OmpP2A and OmpP2B are the first porins described for H. ducreyi.

  7. Structural and Molecular Modeling Features of P2X Receptors

    Directory of Open Access Journals (Sweden)

    Luiz Anastacio Alves

    2014-03-01

    Full Text Available Currently, adenosine 5'-triphosphate (ATP is recognized as the extracellular messenger that acts through P2 receptors. P2 receptors are divided into two subtypes: P2Y metabotropic receptors and P2X ionotropic receptors, both of which are found in virtually all mammalian cell types studied. Due to the difficulty in studying membrane protein structures by X-ray crystallography or NMR techniques, there is little information about these structures available in the literature. Two structures of the P2X4 receptor in truncated form have been solved by crystallography. Molecular modeling has proven to be an excellent tool for studying ionotropic receptors. Recently, modeling studies carried out on P2X receptors have advanced our knowledge of the P2X receptor structure-function relationships. This review presents a brief history of ion channel structural studies and shows how modeling approaches can be used to address relevant questions about P2X receptors.

  8. The selective antagonism of P2X7 and P2Y1 receptors prevents synaptic failure and affects cell proliferation induced by oxygen and glucose deprivation in rat dentate gyrus.

    Directory of Open Access Journals (Sweden)

    Giovanna Maraula

    Full Text Available Purinergic P2X and P2Y receptors are broadly expressed on both neurons and glial cells in the central nervous system (CNS, including dentate gyrus (DG. The aim of this research was to determine the synaptic and proliferative response of the DG to severe oxygen and glucose deprivation (OGD in acute rat hippocampal slices and to investigate the contribution of P2X7 and P2Y1 receptor antagonism to recovery of synaptic activity after OGD. Extracellular field excitatory post-synaptic potentials (fEPSPs in granule cells of the DG were recorded from rat hippocampal slices. Nine-min OGD elicited an irreversible loss of fEPSP and was invariably followed by the appearance of anoxic depolarization (AD. Application of MRS2179 (selective antagonist of P2Y1 receptor and BBG (selective antagonist of P2X7 receptor, before and during OGD, prevented AD appearance and allowed a significant recovery of neurotransmission after 9-min OGD. The effects of 9-min OGD on proliferation and maturation of cells localized in the subgranular zone (SGZ of slices prepared from rats treated with 5-Bromo-2'-deoxyuridine (BrdU were investigated. Slices were further incubated with an immature neuron marker, doublecortin (DCX. The number of BrdU+ cells in the SGZ was significantly decreased 6 hours after OGD. This effect was antagonized by BBG, but not by MRS2179. Twenty-four hours after 9-min OGD, the number of BrdU+ cells returned to control values and a significant increase of DCX immunofluorescence was observed. This phenomenon was still evident when BBG, but not MRS2179, was applied during OGD. Furthermore, the P2Y1 antagonist reduced the number of BrdU+ cells at this time. The data demonstrate that P2X7 and P2Y1 activation contributes to early damage induced by OGD in the DG. At later stages after the insult, P2Y1 receptors might play an additional and different role in promoting cell proliferation and maturation in the DG.

  9. P2X(7) receptor activation enhances SK3 channels- and cystein cathepsin-dependent cancer cells invasiveness.

    Science.gov (United States)

    Jelassi, B; Chantôme, A; Alcaraz-Pérez, F; Baroja-Mazo, A; Cayuela, M L; Pelegrin, P; Surprenant, A; Roger, S

    2011-05-05

    ATP-gated P2X(7) receptors (P2X(7)R) are unusual plasma membrane ion channels that have been extensively studied in immune cells. More recently, P2X(7)R have been described as potential cancer cell biomarkers. However, mechanistic links between P2X(7)R and cancer cell processes are unknown. Here, we show, in the highly aggressive human breast cancer cell line MDA-MB-435s, that P2X(7) receptor is highly expressed and fully functional. Its activation is responsible for the extension of neurite-like cellular prolongations, of the increase in cell migration by 35% and in cell invasion through extracellular matrix by 150%. The change in cancer cell morphology and the increased migration appeared to be due to the activation of Ca(2+)-activated SK3 potassium channels. The enhanced invasion through the extracellular matrix was related to the increase of mature forms of cysteine cathepsins in the extracellular medium, which was independent of SK3 channel activity and not associated with cell death. Pharmacological targeting of P2X(7)R in vivo was crucial for cell invasiveness in a zebrafish model of metastases. Our results demonstrate a novel mechanistic link between P2X(7)R functionality in cancer cells and invasiveness, a key parameter in tumour growth and in the development of metastases. They also suggest a potential therapeutic role for the newly developed P2X(7)R antagonists.

  10. Blockage of P2X7 attenuates acute lung injury in mice by inhibiting NLRP3 inflammasome.

    Science.gov (United States)

    Wang, Shuang; Zhao, Jijun; Wang, Hongyue; Liang, Yingjie; Yang, Niansheng; Huang, Yuefang

    2015-07-01

    NLRP3 inflammasome is engaged in the inflammatory response during acute lung injury (ALI). Purinergic receptor P2X7 has been reported to be upstream of NLRP3 activation. However, the therapeutic implication of P2X7 in ALI remains to be explored. The present study used lipopolysaccharide (LPS)-induced mouse model to investigate the therapeutic potential of P2X7 blockage in ALI. Our results showed that P2X7/NLRP3 inflammasome pathway was significantly upregulated in the lungs of ALI mice as compared with control mice. P2X7 antagonist A438079 suppressed NLRP3/ASC/caspase 1 activation, production of IL-1β, IL-17A and IFN-γ and neutrophil infiltration but not the production of IL-10, resulting in a significant amelioration of lung injury. Moreover, blockage of P2X7 significantly inhibited NLRP3 inflammasome activation and IL-1β production in bone marrow derived macrophages. Similar results were obtained using another P2X7 inhibitor brilliant blue G (BBG) in vivo. Thus, pharmacological blockage of P2X7/NLRP3 pathway can be considered as a potential therapeutic strategy in patients with ALI.

  11. Effect of the purinergic receptor P2X7 on Chlamydia infection in cervical epithelial cells and vaginally infected mice.

    Science.gov (United States)

    Darville, Toni; Welter-Stahl, Lynn; Cruz, Cristiane; Sater, Ali Abdul; Andrews, Charles W; Ojcius, David M

    2007-09-15

    Ligation of the purinergic receptor, P2X7R, with its agonist ATP has been previously shown to inhibit intracellular infection by chlamydiae and mycobacteria in macrophages. The effect of P2X7R on chlamydial infection had never been investigated in the preferred target cells of chlamydiae, cervical epithelial cells, nor in vaginally infected mice. In this study, we show that treatment of epithelial cells with P2X7R agonists inhibits partially Chlamydia infection in epithelial cells. Chelation of ATP with magnesium or pretreatment with a P2X7R antagonist blocks the inhibitory effects of ATP. Similarly to previous results obtained with macrophages, ATP-mediated inhibition of infection in epithelial cells requires activation of host-cell phospholipase D. Vaginal infection was also more efficient in P2X7R-deficient mice, which also displayed a higher level of acute inflammation in the endocervix, oviduct, and mesosalpingeal tissues than in infected wild-type mice. However, secretion of IL-1beta, which requires P2X7R ligation during infection by other pathogens, was decreased mildly and only at short times of infection. Taken together, these results suggest that P2X7R affects Chlamydia infection by directly inhibiting infection in epithelial cells, rather than through the ability of P2X7R to modulate IL-1beta secretion.

  12. Electrophysiological studies of upregulated P2X7 receptors in rat superior cervical ganglia after myocardial ischemic injury.

    Science.gov (United States)

    Kong, Fanjun; Liu, Shuangmei; Xu, Changshui; Liu, Jun; Li, Guodong; Li, Guilin; Gao, Yun; Lin, Hong; Tu, Guihua; Peng, Haiying; Qiu, Shuyi; Fan, Bo; Zhu, Qicheng; Yu, Shicheng; Zheng, Chaoran; Liang, Shangdong

    2013-09-01

    Myocardial ischemic injury activates cardiac sympathetic afferent fibers and elicits a sympathoexcitatory reflex by exciting sympathetic efferent action, with resultant augmentation of myocardial oxygen consumption, leading to a vicious cycle of exaggerating myocardial ischemia. P2X7 receptor participates in the neuronal functions and the neurological disorders. This study examined the role of P2X7 receptor of superior cervical ganglia (SCG) in sympathoexcitatory reflex. Our results showed that the expression of P2X7 receptor at both mRNA and protein in SCG was increased after myocardial ischemic injury. P2X7 receptor agonists at the same concentration activated much larger amplitudes of the currents in the SCG neurons of myocardial ischemic rats than those in control rats. P2X7 receptor antagonist (brilliant blue G, BBG) significantly inhibited P2X7 receptor agonist-activated currents in the SCG neurons. Excessive phosphorylation of MAPK ERK1/2 upon the activation of P2X7 receptor might be a mechanism mediating the signal transduction after myocardial ischemic injury. Therefore, the sensitized P2X7 receptor in SCG was involved in the nociceptive transmission of sympathoexcitatory reflex induced by myocardial ischemic injury.

  13. STABILITY OF P2 METHODS FOR NEUTRON TRANSPORT EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    袁光伟; 沈智军; 沈隆钧; 周毓麟

    2002-01-01

    In this paper the P2 approximation to the one-group planar neutron transport theory is discussed. The stability of the solutions for P2 equations with general boundary conditions, including the Marshak boundary condition, is proved. Moreover,the stability of the up-wind difference scheme for the P2 equation is demonstrated.

  14. Melittin modulates keratinocyte function through P2 receptor-dependent ADAM activation.

    Science.gov (United States)

    Sommer, Anselm; Fries, Anja; Cornelsen, Isabell; Speck, Nancy; Koch-Nolte, Friedrich; Gimpl, Gerald; Andrä, Jörg; Bhakdi, Sucharit; Reiss, Karina

    2012-07-06

    Melittin, the major component of the bee venom, is an amphipathic, cationic peptide with a wide spectrum of biological properties that is being considered as an anti-inflammatory and anti-cancer agent. It modulates multiple cellular functions but the underlying mechanisms are not clearly understood. Here, we report that melittin activates disintegrin-like metalloproteases (ADAMs) and that downstream events likely contribute to the biological effects evoked by the peptide. Melittin stimulated the proteolysis of ADAM10 and ADAM17 substrates in human neutrophil granulocytes, endothelial cells and murine fibroblasts. In human HaCaT keratinocytes, melittin induced shedding of the adhesion molecule E-cadherin and release of TGF-α, which was accompanied by transactivation of the EGF receptor and ERK1/2 phosphorylation. This was followed by functional consequences such as increased keratinocyte proliferation and enhanced cell migration. Evidence is provided that ATP release and activation of purinergic P2 receptors are involved in melittin-induced ADAM activation. E-cadherin shedding and EGFR phosphorylation were dose-dependently reduced in the presence of ATPases or P2 receptor antagonists. The involvement of P2 receptors was underscored in experiments with HEK cells, which lack the P2X7 receptor and showed strikingly increased response to melittin stimulation after transfection with this receptor. Our study provides new insight into the mechanism of melittin function which should be of interest particularly in the context of its potential use as an anti-inflammatory or anti-cancer agent.

  15. P2X7 receptors and Fyn kinase mediate ATP-induced oligodendrocyte progenitor cell migration.

    Science.gov (United States)

    Feng, Ji-Feng; Gao, Xiao-Fei; Pu, Ying-Yan; Burnstock, Geoffrey; Xiang, Zhenghua; He, Cheng

    2015-09-01

    Recruitment of oligodendrocyte precursor cells (OPCs) to the lesions is the most important event for remyelination after central nervous system (CNS) injury or in demyelinating diseases. However, the underlying molecular mechanism is not fully understood. In the present study, we found high concentrations of ATP could increase the number of migrating OPCs in vitro, while after pretreatment with oxidized ATP (a P2X7 receptor antagonist), the promotive effect was attenuated. The promotive effect of 2'(3')-O-(4-benzoylbenzoyl) adenosine 5'-triphosphate (BzATP) (a P2X7 receptor agonist) was more potent than ATP. After incubation with BzATP, the activity of Fyn, one member of the Src family of kinases, was enhanced. Moreover, the interaction between P2X7 and Fyn was identified by co-immunoprecipitation. After blocking the activity of Fyn or down-regulating the expression of Fyn, the migration of OPCs induced by BzATP was inhibited. These data indicate that P2X7 receptors/Fyn may mediate ATP-induced OPC migration under pathological conditions.

  16. P2X7 Receptor Activation Regulates Microglial Cell Death During Oxygen-Glucose Deprivation”

    OpenAIRE

    Eyo, Ukpong B.; Miner, Sam A.; Ahlers, Katelin E.; Wu, Long-Jun; Dailey, Michael E.

    2013-01-01

    Brain-resident microglia may promote tissue repair following stroke but, like other cells, they are vulnerable to ischemia. Here we identify mechanisms involved in microglial ischemic vulnerability. Using time-lapse imaging of cultured BV2 microglia, we show that simulated ischemia (oxygen-glucose deprivation; OGD) induces BV2 microglial cell death. Removal of extracellular Ca2+ or application of Brilliant Blue G (BBG), a potent P2X7 receptor (P2X7R) antagonist, protected BV2 microglia from d...

  17. Shockwaves induce osteogenic differentiation of human mesenchymal stem cells through ATP release and activation of P2X7 receptors.

    Science.gov (United States)

    Sun, Dahui; Junger, Wolfgang G; Yuan, Changji; Zhang, Wenyan; Bao, Yi; Qin, Daming; Wang, Chengxue; Tan, Lei; Qi, Baochang; Zhu, Dong; Zhang, Xizheng; Yu, Tiecheng

    2013-06-01

    Shockwave treatment promotes bone healing of nonunion fractures. In this study, we investigated whether this effect could be due to adenosine 5'-triphosphate (ATP) release-induced differentiation of human mesenchymal stem cells (hMSCs) into osteoprogenitor cells. Cultured bone marrow-derived hMSCs were subjected to shockwave treatment and ATP release was assessed. Osteogenic differentiation and mineralization of hMSCs were evaluated by examining alkaline phosphatase activity, osteocalcin production, and calcium nodule formation. Expression of P2X7 receptors and c-fos and c-jun mRNA was determined with real-time reverse transcription polymerase chain reaction and Western blotting. P2X7-siRNA, apyrase, P2 receptor antagonists, and p38 MAPK inhibitors were used to evaluate the roles of ATP release, P2X7 receptors, and p38 MAPK signaling in shockwave-induced osteogenic hMSCs differentiation. Shockwave treatment released significant amounts (≈ 7 μM) of ATP from hMSCs. Shockwaves and exogenous ATP induced c-fos and c-jun mRNA transcription, p38 MAPK activation, and hMSC differentiation. Removal of ATP with apyrase, targeting of P2X7 receptors with P2X7-siRNA or selective antagonists, or blockade of p38 MAPK with SB203580 prevented osteogenic differentiation of hMSCs. Our findings indicate that shockwaves release cellular ATP that activates P2X7 receptors and downstream signaling events that caused osteogenic differentiation of hMSCs. We conclude that shockwave therapy promotes bone healing through P2X7 receptor signaling, which contributes to hMSC differentiation.

  18. Uridine Triphosphate Thio Analogues Inhibit Platelet P2Y12 Receptor and Aggregation

    Science.gov (United States)

    Gündüz, Dursun; Tanislav, Christian; Sedding, Daniel; Parahuleva, Mariana; Santoso, Sentot; Troidl, Christian; Hamm, Christian W.; Aslam, Muhammad

    2017-01-01

    Platelet P2Y12 is an important adenosine diphosphate (ADP) receptor that is involved in agonist-induced platelet aggregation and is a valuable target for the development of anti-platelet drugs. Here we characterise the effects of thio analogues of uridine triphosphate (UTP) on ADP-induced platelet aggregation. Using human platelet-rich plasma, we demonstrate that UTP inhibits P2Y12 but not P2Y1 receptors and antagonises 10 µM ADP-induced platelet aggregation in a concentration-dependent manner with an IC50 value of ~250 µM. An eight-fold higher platelet inhibitory activity was observed with a 2-thio analogue of UTP (2S-UTP), with an IC50 of 30 µM. The 4-thio analogue (4S-UTP) with an IC50 of 7.5 µM was 33-fold more effective. A three-fold decrease in inhibitory activity, however, was observed by introducing an isobutyl group at the 4S- position. A complete loss of inhibition was observed with thio-modification of the γ phosphate of the sugar moiety, which yields an enzymatically stable analogue. The interaction of UTP analogues with P2Y12 receptor was verified by P2Y12 receptor binding and cyclic AMP (cAMP) assays. These novel data demonstrate for the first time that 2- and 4-thio analogues of UTP are potent P2Y12 receptor antagonists that may be useful for therapeutic intervention. PMID:28146050

  19. Emerging role of P2X7 receptors in CNS health and disease.

    Science.gov (United States)

    Tewari, Manju; Seth, Pankaj

    2015-11-01

    Purinergic signalling in the brain is becoming an important focus in the study of CNS health and disease. Various purinergic receptors are found to be present in different brain cells in varying extent, which get activated upon binding of ATP or its analogues. Conventionally, ATP was considered only as a major metabolic fuel of the cell but its recognition as a neurotransmitter in early 1970s, brought meaningful insights in neuron glia crosstalk, participating in various physiological functions in the brain. P2X7R, a member of ligand gated purinergic receptor (P2X) family, is gaining attention in the field of neuroscience because of its emerging role in broad spectrum of ageing and age related neurological disorders. The aim of this review is to provide an overview about the structure and function of P2X7R highlighting its unique features which distinguish it from the other members of its family. This review critically analyzes the literature mentioning the details about the agonist and antagonist of the P2X7R. It also emphasizes the advancements in understanding the dual role of P2X7R in brain development and disorders inviting meaningful insights about its involvement in Alzheimer's disease, Huntington's disease, Multiple Sclerosis, Neuropathic pain, Spinal Cord Injury and NeuroAIDS. Exploring the roles of P2X7R in detail is critical to identify its therapeutic potential in the treatment of acute and chronic neurodegenerative diseases. Moreover, this review also helps to raise more interest in the neurobiology of the purinergic receptors and thus providing new avenues for future research.

  20. Functional expression of purinergic P2X7 receptors in pregnant rat myometrium.

    Science.gov (United States)

    Miyoshi, Hiroshi; Yamaoka, Kaoru; Urabe, Satoshi; Kodama, Miho; Kudo, Yoshiki

    2010-04-01

    ATP has been reported to enhance the membrane conductance of myometrial cells and uterine contractility. Purinergic P2 receptor expression has been reported in the myometrium, using molecular biology, but the functional identity of the receptor subtype has not been determined. In this study, ATP-induced currents were recorded and characterized in single myometrial cells from pregnant rats using whole cell patch clamping. Extracellular ATP was applied in the range of 10 muM-1 mM and induced currents with an EC(50) of 74 muM, with no desensitization, time dependency, or voltage dependency. The currents induced carried multiple monovalent cations, with conductances ranked as K(+) > Cs(+) > Li(+) > Na(+). They were activated by P2X receptor agonists, with their effectiveness ranked as 2',3'-O-(4-benzoylbenzoyl)-ATP > ATP > alphabeta-methylene-ATP > 2-methylthio ATP > or = UTP > or = GTP > ADP. These currents were blocked by the selective P2X7 receptor antagonist 3-[5-(2,3-dichlorophenyl)-1 H-tetrazol-1-yl]methyl pyridine (A-438079). We therefore concluded that ATP-induced currents in rat myometrial cells crossed cell membranes via P2X7 receptors. We further showed that the ATP-induced currents were blocked by extracellular Mg(2+) (IC(50) = 0.26 mM). Clinically, administering extracellular Mg(2+) is known to inhibit uterine contraction. It therefore seems likely that uterine contraction may be induced by raised extracellular ATP and suppressed via Mg(2+) inhibiting P2X7 receptors. Further research is needed into the P2X7 receptor as a therapeutic target in abnormal uterine contraction, as a possible treatment for premature labor.

  1. Providing VoD Streaming Using P2P Networks

    Science.gov (United States)

    Pedro Muñoz-Gea, Juan; Malgosa-Sanahuja, Josemaria; Manzanares-Lopez, Pilar; Carlos Sanchez-Aarnoutse, Juan

    Overlays and P2P systems, initially developed to support IP multicast and file-sharing, have moved beyond that functionality. They are also proving to be key technologies for the delivery of video streaming. Recently, there have been a number of successful deployments for "live" P2P streaming. However, the question remains open whether similar P2P technologies can be used to provide VoD (Video-On-Demand) services. A P2P VoD service is more challenging to design than a P2P live streaming system because the system should allow users arriving at arbitrary times to watch (arbitrary parts of) the video.

  2. Paroxetine suppresses recombinant human P2X7 responses

    OpenAIRE

    Dao-Ung, Phuong; Skarratt, Kristen; Fuller, Stephen; Stokes, Leanne

    2015-01-01

    P2X7 receptor (P2X7) activity may link inflammation to depressive disorders. Genetic variants of human P2X7 have been linked with major depression and bipolar disorders, and the P2X7 knockout mouse has been shown to exhibit anti-depressive-like behaviour. P2X7 is an ATP-gated ion channel and is a major regulator of the pro-inflammatory cytokine interleukin 1β (IL-1β) secretion from monocytes and microglia. We hypothesised that antidepressants may elicit their mood enhancing effects in part vi...

  3. Research of P2P SIP technology%P2P SIP技术的研究

    Institute of Scientific and Technical Information of China (English)

    隋晋光; 鲁士文

    2007-01-01

    在阐述P2P和SIP技术的基础上,引出了一种二者融合的新技术--P2P SIP,提出了采用P2P SIP技术系统的体系结构、工作方式,并且对P2P SIP技术的安全性问题进行了分析.

  4. Risk Management of P2P Internet Financing Service Platform

    Science.gov (United States)

    Yalei, Li

    2017-09-01

    Since 2005, the world’s first P2P Internet financing service platform Zopa in UK was introduced, in the development of “Internet +” trend, P2P Internet financing service platform has been developed rapidly. In 2007, China’s first P2P platform “filming loan” was established, marking the P2P Internet financing service platform to enter China and the rapid development. At the same time, China’s P2P Internet financing service platform also appeared in different forms of risk. This paper focuses on the analysis of the causes of risk of P2P Internet financing service platform and the performance of risk management process. It provides a solution to the Internet risk management plan, and explains the risk management system of the whole P2P Internet financing service platform and the future development direction.

  5. Network-Aware DHT-Based P2P Systems

    Science.gov (United States)

    Fayçal, Marguerite; Serhrouchni, Ahmed

    P2P networks lay over existing IP networks and infrastructure. This chapter investigates the relation between both layers, details the motivations for network awareness in P2P systems, and elucidates the requirements P2P systems have to meet for efficient network awareness. Since new P2P systems are mostly based on DHTs, we also present and analyse DHT-based architectures. And after a brief presentation of different existing network-awareness solutions, the chapter goes on effective cooperation between P2P traffic and network providers' business agreements, and introduces emerging DHT-based P2P systems that are network aware through a semantic defined for resource sharing. These new systems ensure also a certain context-awareness. So, they are analyzed and compared before an open end on prospects of network awareness in P2P systems.

  6. Distribution of the purinegic receptors P2X(4) and P2X(6) during rat gut development.

    Science.gov (United States)

    García-Alcocer, Guadalupe; Padilla, Karla; Rodríguez, Angelina; Miledi, Ricardo; Berumen, Laura C

    2012-02-16

    The purinergic receptors P2X(4) and P2X(6) are ion channels activated by ATP. These receptors are present in the gastrointestinal tract, and they are involved in synaptic transmission, taste sensation, and pain, among other functions. In this work, we studied the distribution of P2X(4) and P2X(6) receptors in proximal and distal regions of the gut newborn and adult rats. Using immunohistochemistry, purinergic receptors were found in gut epithelial cells and capillary vessels. In both proximal and distal regions of newborn rats, we observed P2X(4) signal in epithelial cells, whereas P2X(6) was present in capillary vessels in the proximal region and to a lesser extent in the distal region. In both regions of adult gut, we observed P2X(4) and P2X(6) immunostain in the capillary vessels. Semi-quantification indicated a significant difference in the amount of P2X(4) between proximal regions, whereas the P2X(6) content of both newborn regions differed from that in adult proximal gut. We conclude that P2X(4) and P2X(6) purinoreceptors are present in the gut from birth and that they are differentially distributed among regions.

  7. ATP induces P2X7 receptor-independent cytokine and chemokine expression through P2X1 and P2X3 receptors in murine mast cells.

    Science.gov (United States)

    Bulanova, Elena; Budagian, Vadim; Orinska, Zane; Koch-Nolte, Friedrich; Haag, Friedrich; Bulfone-Paus, Silvia

    2009-04-01

    Extracellular ATP mediates a diverse array of biological responses in many cell types and tissues, including immune cells. We have demonstrated that ATP induces purinergic receptor P2X(7) mediated membrane permeabilization, apoptosis, and cytokine expression in murine mast cells (MCs). Here, we report that MCs deficient in the expression of the P2X(7) receptor are resistant to the ATP-induced membrane permeabilization and apoptosis. However, ATP affects the tyrosine phosphorylation pattern of P2X(7)knockout cells, leading to the activation of ERK1/2. Furthermore, ATP induces expression of several cytokines and chemokines in these cells, including IL-4, IL-6, IFN-gamma, TNF-alpha, RANTES, and MIP-2, at the mRNA level. In addition, the release of IL-6 and IL-13 to cell-conditioned medium was confirmed by ELISA. The ligand selectivity and pharmacological profile indicate the involvement of two P2X family receptors, P2X(1) and P2X(3). Thus, depending on genetic background, particular tissue microenvironment, and ATP concentration, MCs can presumably engage different P2X receptor subtypes, which may result in functionally distinct biological responses to extracellular nucleotides. This finding highlights a novel level of complexity in the sophisticated biology of MCs and may facilitate the development of new therapeutic approaches to modulate MC activities.

  8. Impaired P2X1 Receptor-Mediated Adhesion in Eosinophils from Asthmatic Patients.

    Science.gov (United States)

    Wright, Adam; Mahaut-Smith, Martyn; Symon, Fiona; Sylvius, Nicolas; Ran, Shaun; Bafadhel, Mona; Muessel, Michelle; Bradding, Peter; Wardlaw, Andrew; Vial, Catherine

    2016-06-15

    Eosinophils play an important role in the pathogenesis of asthma and can be activated by extracellular nucleotides released following cell damage or inflammation. For example, increased ATP concentrations were reported in bronchoalveolar lavage fluids of asthmatic patients. Although eosinophils are known to express several subtypes of P2 receptors for extracellular nucleotides, their function and contribution to asthma remain unclear. In this article, we show that transcripts for P2X1, P2X4, and P2X5 receptors were expressed in healthy and asthmatic eosinophils. The P2X receptor agonist α,β-methylene ATP (α,β-meATP; 10 μM) evoked rapidly activating and desensitizing inward currents (peak 18 ± 3 pA/pF at -60 mV) in healthy eosinophils, typical of P2X1 homomeric receptors, which were abolished by the selective P2X1 antagonist NF449 (1 μM) (3 ± 2 pA/pF). α,β-meATP-evoked currents were smaller in eosinophils from asthmatic patients (8 ± 2 versus 27 ± 5 pA/pF for healthy) but were enhanced following treatment with a high concentration of the nucleotidase apyrase (17 ± 5 pA/pF for 10 IU/ml and 11 ± 3 pA/pF for 0.32 IU/ml), indicating that the channels are partially desensitized by extracellular nucleotides. α,β-meATP (10 μM) increased the expression of CD11b activated form in eosinophils from healthy, but not asthmatic, donors (143 ± 21% and 108 ± 11% of control response, respectively). Furthermore, α,β-meATP increased healthy (18 ± 2% compared with control 10 ± 1%) but not asthmatic (13 ± 1% versus 10 ± 0% for control) eosinophil adhesion. Healthy human eosinophils express functional P2X1 receptors whose activation leads to eosinophil αMβ2 integrin-dependent adhesion. P2X1 responses are constitutively reduced in asthmatic compared with healthy eosinophils, probably as the result of an increase in extracellular nucleotide concentration.

  9. Purinergic P2X7 receptors mediate cell death in mouse cerebellar astrocytes in culture.

    Science.gov (United States)

    Salas, Elvira; Carrasquero, Luz María G; Olivos-Oré, Luis A; Bustillo, Diego; Artalejo, Antonio R; Miras-Portugal, Maria Teresa; Delicado, Esmerilda G

    2013-12-01

    The brain distribution and functional role of glial P2X7 receptors are broader and more complex than initially anticipated. We characterized P2X7 receptors from cerebellar astrocytes at the molecular, immunocytochemical, biophysical, and cell physiologic levels. Mouse cerebellar astrocytes in culture express mRNA coding for P2X7 receptors, which is translated into P2X7 receptor protein as proven by Western blot analysis and immunocytochemistry. Fura-2 imaging showed cytosolic calcium responses to ATP and the synthetic analog 3'-O-(4-benzoyl)benzoyl-ATP (BzATP) exhibited two components, namely an initial transient and metabotropic component followed by a sustained one that depended on extracellular calcium. This latter component, which was absent in astrocytes from P2X7 receptor knockout mice (P2X7 KO), was modulated by extracellular Mg(2+), and was sensitive to Brilliant Blue G (BBG) and 3-(5-(2,3-dichlorophenyl)-1H-tetrazol-1-yl)methyl pyridine (A438079) antagonism. BzATP also elicited inwardly directed nondesensitizing whole-cell ionic currents that were reduced by extracellular Mg(2+) and P2X7 antagonists (BBG and calmidazolium). In contrast to that previously reported in rat cerebellar astrocytes, sustained BzATP application induced a gradual increase in membrane permeability to large cations, such as N-methyl-d-glucamine and 4-[3-methyl-2(3H)-benzoxazolylidene)-methyl]-1-[3-(triethylammonio)propyl]diiodide, which ultimately led to the death of mouse astrocytes. Cerebellar astrocyte cell death was prevented by BBG but not by calmidazolium, removal of extracellular calcium, or treatment with the caspase-3 inhibitor, benzyloxycarbonyl-Asp(OMe)-Glu(OMe)-Val-Asp(OMe)-fluoromethylketone, thus suggesting a necrotic-type mechanism of cell death. Since this cellular response was not observed in astrocytes from P2X7 KO mice, this study suggests that stimulation of P2X7 receptor may convey a cell death signal to cerebellar astrocytes in a species-specific manner.

  10. Reducing cardiovascular risk factors in non-selected outpatients with schizophrenia

    DEFF Research Database (Denmark)

    Hansen, Mette Vinther; Hjorth, Peter; Kristiansen, Christina Blanner;

    2016-01-01

    glucose, serum lipids, and information on smoking and alcohol were obtained. Results: On average, small significant increases in body mass index (BMI) and waist circumferences were observed while small non-significant improvements in other cardiovascular risk factors were seen. Patients with high baseline......Objectives: Cardiovascular diseases are the most common causes of premature death in patients with schizophrenia. We aimed at reducing cardiovascular risk factors in non-selected outpatients with schizophrenia using methods proven effective in short-term trials. Furthermore, we examined whether any...... motivated to participate in the interventions, and it was difficult to monitor the recommended metabolic risk measures in the patient group. Future research should focus on simple strategies in health promotion that can be integrated into routine care....

  11. 基于P2P的SIP网络研究%Research of SIP Internet based on P2P

    Institute of Scientific and Technical Information of China (English)

    李桂林; 李建华

    2007-01-01

    在现有P2P应用和SIP协议特点的基础上,提出了分层P2P-SIP网络设计方案,详细分析了P2P-SIP节点的实现机制.该设计采用P2P技术提高传统SIP网络的可靠性、自组织性,并解决了异构P2P-SIP网络互通问题.

  12. P2X1 receptors and the endothelium

    Directory of Open Access Journals (Sweden)

    LS Harrington

    2005-03-01

    Full Text Available Adenosine triphosphate (ATP is now established as a principle vaso-active mediator in the vasculature. Its actions on arteries are complex, and are mediated by the P2X and P2Y receptor families. It is generally accepted that ATP induces a bi-phasic response in arteries, inducing contraction via the P2X and P2Y receptors on the smooth muscle cells, and vasodilation via the actions of P2Y receptors located on the endothelium. However, a number of recent studies have placed P2X1 receptors on the endothelium of some arteries. The use of a specific P2X1 receptor ligand, a, b methylene ATP has demonstrated that P2X1 receptors also have a bi-functional role. The actions of ATP on P2X1 receptors is therefore dependant on its location, inducing contraction when located on the smooth muscle cells, and dilation when expressed on the endothelium, comparable to that of P2Y receptors.

  13. P2X receptors: New players in cancer pain

    Institute of Scientific and Technical Information of China (English)

    Alessia; Franceschini; Elena; Adinolfi

    2014-01-01

    Pain is unfortunately a quite common symptom for cancer patients. Normally pain starts as an episodic experience at early cancer phases to become chronic in later stages. In order to improve the quality of life of oncological patients, anti-cancer treatments are often accompanied by analgesic therapies. The P2 X receptor are adenosine triphosphate(ATP) gated ion channels expressed by several cells including neurons, cancer and immune cells. Purinergic signaling through P2 X receptors recently emerged as possible common pathway for cancer onset/growth and pain sensitivity. Indeed, tumor microenvironment is rich in extracellular ATP, which has a role in both tumor development and pain sensation. The study of the different mechanisms by which P2 X receptors favor cancer progression and relative pain, represents an interesting challenge to design integrated therapeutic strategies for oncological patients. This review summarizes recent findings linking P2 X receptors and ATP to cancer growth, progression and related pain. Special attention has been paid to the role of P2X2, P2X3, P2X4 and P2X7 in the genesisof cancer pain and to the function of P2X7 in tumor growth and metastasis. Therapeutic implications of the administration of different P2 X receptor blockers to alleviate cancer-associated pain sensations contemporarily reducing tumor progression are also discussed.

  14. HSP90 Regulation of P2X7 Receptor Function Requires an Intact Cytoplasmic C-Terminus.

    Science.gov (United States)

    Migita, Keisuke; Ozaki, Taku; Shimoyama, Shuji; Yamada, Junko; Nikaido, Yoshikazu; Furukawa, Tomonori; Shiba, Yuko; Egan, Terrance M; Ueno, Shinya

    2016-08-01

    P2X7 receptors (P2X7Rs) are ATP-gated ion channels that display the unusual property of current facilitation during long applications of agonists. Here we show that facilitation disappears in chimeric P2X7Rs containing the C-terminus of the P2X2 receptor (P2X2R), and in a truncated P2X7R missing the cysteine-rich domain of the C-terminus. The chimeric and truncated receptors also show an apparent decreased permeability to N-methyl-d-glucamine(+) (NMDG(+)). The effects of genetic modification of the C-terminus on NMDG(+) permeability were mimicked by preapplication of the HSP90 antagonist geldanamycin to the wild-type receptor. Further, the geldanamycin decreased the shift in the reversal potential of the ATP-gated current measured under bi-ionic NMDG(+)/Na(+) condition without affecting the ability of the long application of agonist to facilitate current amplitude. Taken together, the results suggest that HSP90 may be essential for stabilization and function of P2X7Rs through an action on the cysteine-rich domain of the cytoplasmic the C-terminus.

  15. In silico Approach for Anti-Thrombosis Drug Discovery: P2Y1R Structure-Based TCMs Screening

    Science.gov (United States)

    Yi, Fan; Sun, Le; Xu, Li-jia; Peng, Yong; Liu, Hai-bo; He, Chun-nian; Xiao, Pei-gen

    2017-01-01

    Cardiovascular diseases (CVDs), including thrombosis, which is induced by platelet aggregation, are the leading cause of mortality worldwide. The P2Y1 receptor (P2Y1R) facilitates platelet aggregation and is thus an important potential anti-thrombotic drug target. The P2Y1R protein structure contains a binding site for receptor antagonist MRS2500 within its seven-transmembrane bundle, which also provides suitable pockets for numerous other ligands to act as nucleotide antagonists of P2Y1R. The Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) comprises 499 Chinese Pharmacopoeia-registered herbs and the structure information for 29,384 ingredients. In silico docking of these compounds into the P2Y1R protein structure within the MRS2500 pocket can identify potential antithrombotic drugs from natural medicinal plants. Docking studies were performed and scored to evaluate ligand-binding affinities. In this study, a total of 8987 compounds from Traditional Chinese Medicine (TCM) were filtered by Lipinski's rule of five, and their ideal oral-intake properties were evaluated. Of these, 1656 compounds distributed in 443 herbs docked into the P2Y1R-MRS2500 structure in 16,317 poses. A total of 38 compounds were ranked with a DockScore above 70, and these may have significant potential for development into anti-thrombosis drugs. These computational results suggested that licorice (Glycyrrhiza uralensis Fisch), cimicifugae (Cimicifuga foetida L.), and ganoderma (Ganoderma lucidum Karst) and their chemical constituents, which have not previously been widely used for anti-thrombosis, may have unexpected effects on platelet aggregation. Moreover, two types of triterpene scaffolds summarized from 10 compounds were distributed in these three herbs and also docked into P2Y1R. These scaffold structures may be utilized for the development of drugs to inhibit platelet aggregation. PMID:28119608

  16. Research and Development of P2P Worms

    Institute of Scientific and Technical Information of China (English)

    Li You; Zhi-Guang Qin

    2011-01-01

    With the development and the application of many popular peer-to-peer (P2P) systems such as eMule and BitTorrent,worms probably employ the features of these P2P networks to put them at risk.Some features,such as the local routing table and the application routing mechanism,are helpful to quickly distribute the P2P worms into the networks.This paper aims to give a comprehensive survey of P2P worms.The definition and the classification of P2P worms are discussed firstly.Then,the research and development of P2P worms, including experimental analysis,propagation modeling,and defensive approaches,are addressed and analyzed in detail.

  17. The Largest Eigenvalue of Graph Cmk(P2,…,P2,Pl)%图Cmk(P2,…,P2,Pl)的最大特征值

    Institute of Scientific and Technical Information of China (English)

    杜先云; 任秋道

    2009-01-01

    设圈C=v1 v2…vm v1,m≥3.在圈C的顶点vil,vi2,…,vik上分别悬挂k条路pn1,pn2,…,Pnk的图记为Ci1,i2….ik(Pn1,Pn2,…Pnk),其中1≤ij≤m,m,1 ≤j≤k.在顶点口vm上悬挂k条路Pn1,Pn2,…,pnk的图简记为Cmk(Pn1,Pn2,…,Pnk).利用图Cmk(P2,…,P2,P1)的特征多项式获得:λ1(Cmk+1(P2,…,P2,Pl-1))≥λ1(Cnk(P2,…,P2,Pl))≥2,其中,k,l ∈ N,l≥3.

  18. The role of P2X7 receptor in ATP-mediated human leukemia cell death:calcium influx-independent

    Institute of Scientific and Technical Information of China (English)

    Xiujun Zhang; Lijun Meng; Baoling He; Jing Chen; Peng Liu; Jie Zhao; Yufen Zhang; Ming Li; Dong An

    2009-01-01

    Activation of the P2X7 receptor leads to a rapid,bidirectional flux of cations, causing broad range of hiological responses including cytotoxicity.However,the mechanism of P2X7-mediated cytotoxicity remains largely unexplored.In our previous study,the lack of P2X7-mediated calcium response under normal conditions was found in P2X7+ hematopoietic cell lines.In this study, the P2X7-mediated cytotoxicity in different type of cells(P2X7-,P2X7+ with calcium response,and P2X7+ without calcium response)was investigated.Our results showed that P2X7 agonists, adenosine 5'-triphosphate(ATP)or 2'+3'-O-(4 benzoylbenzoyl)ATP,dose-dependently reduced the cell viability in all P2X7+ cells tested,including J6-1,LCL,and Namalva cells which are negative for P2X7-mediated calcium response, although these effects were lower than those observed in KG1a cells which has normal P2X7 functions.The cytotoxic effect could be blocked by P2X7antagonists, oxidized ATP and 1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine.In addition,externalization of phosphatidylserine could be detected in a time-dependent manner and apoptotic morphological changes Could be observed after the activation of P2X7 receptor in J6-1 cells.Furthermore,P2X7-mediated pore formation could be detected in KG1a and J6-1 cells under low-ionic conditions,but not under low-divalent conditions.These effects could not be observed in P2X7-Ramos cells.These results suggested that P2X7 receptor-mediated cytotoxic effects may occur independent of calcium response.

  19. Association between P2X7 Receptor Polymorphisms and Bone Status in Mice.

    Science.gov (United States)

    Syberg, Susanne; Schwarz, Peter; Petersen, Solveig; Steinberg, Thomas H; Jensen, Jens-Erik Beck; Teilmann, Jenni; Jørgensen, Niklas Rye

    2012-01-01

    Macrophages from mouse strains with the naturally occurring mutation P451L in the purinergic receptor P2X7 have impaired responses to agonists (1). Because P2X7 receptors are expressed in bone cells and are implicated in bone physiology, we asked whether strains with the P451L mutation have a different bone phenotype. By sequencing the most common strains of inbred mice, we found that only a few strains (BALB, NOD, NZW, and 129) were harboring the wild allelic version of the mutation (P451) in the gene for the purinergic receptor P2X7. The strains were compared by means of dual energy X-ray absorptiometry (DXA), bone markers, and three-point bending. Cultured osteoclasts were used in the ATP-induced pore formation assay. We found that strains with the P451 allele (BALB/cJ and 129X1/SvJ) had stronger femurs and higher levels of the bone resorption marker C-telopeptide collagen (CTX) compared to C57Bl/6 (B6) and DBA/2J mice. In strains with the 451L allele, pore-formation activity in osteoclasts in vitro was lower after application of ATP. In conclusion, two strains with the 451L allele of the naturally occurring mutation P451L, have weaker bones and lower levels of CTX, suggesting lower resorption levels in these animals, which could be related to the decreased ATP-induced pore formation observed in vitro. The importance of these findings for the interpretation of the earlier reported effects of P2X7 in mice is discussed, along with strategies in developing a murine model for testing the therapeutic effects of P2X7 agonists and antagonists upon postmenopausal osteoporosis.

  20. Association between P2X7 Receptor Polymorphisms and Bone Status in Mice

    Directory of Open Access Journals (Sweden)

    Susanne Syberg

    2012-01-01

    Full Text Available Macrophages from mouse strains with the naturally occurring mutation P451L in the purinergic receptor P2X7 have impaired responses to agonists (1. Because P2X7 receptors are expressed in bone cells and are implicated in bone physiology, we asked whether strains with the P451L mutation have a different bone phenotype. By sequencing the most common strains of inbred mice, we found that only a few strains (BALB, NOD, NZW, and 129 were harboring the wild allelic version of the mutation (P451 in the gene for the purinergic receptor P2X7. The strains were compared by means of dual energy X-ray absorptiometry (DXA, bone markers, and three-point bending. Cultured osteoclasts were used in the ATP-induced pore formation assay. We found that strains with the P451 allele (BALB/cJ and 129X1/SvJ had stronger femurs and higher levels of the bone resorption marker C-telopeptide collagen (CTX compared to C57Bl/6 (B6 and DBA/2J mice. In strains with the 451L allele, pore-formation activity in osteoclasts in vitro was lower after application of ATP. In conclusion, two strains with the 451L allele of the naturally occurring mutation P451L, have weaker bones and lower levels of CTX, suggesting lower resorption levels in these animals, which could be related to the decreased ATP-induced pore formation observed in vitro. The importance of these findings for the interpretation of the earlier reported effects of P2X7 in mice is discussed, along with strategies in developing a murine model for testing the therapeutic effects of P2X7 agonists and antagonists upon postmenopausal osteoporosis.

  1. P2X7 receptors in neurohypophysial terminals: evidence for their role in arginine-vasopressin secretion.

    Science.gov (United States)

    Cuadra, Adolfo E; Custer, Edward E; Bosworth, Elizabeth L; Lemos, José R

    2014-03-01

    Arginine-vasopressin (AVP) plays a major role in maintaining cardiovascular function and related pathologies. The mechanism involved in its release into the circulation is complex and highly regulated. Recent work has implicated the purinergic receptor, P2X7R, in a role for catecholamine-enhanced AVP release in the rat hypothalamic-neurohypophysial (NH) system. However, the site of P2X7R action in this endocrine system, and whether or not it directly mediates release in secretory neurons have not been determined. We hypothesized that the P2X7R is expressed and mediates AVP release in NH terminals. P2X7R function was first examined by patch-clamp recordings in isolated NH terminals. Results revealed that subpopulations of isolated terminals displayed either high ATP-sensitivity or low ATP-sensitivity, the latter of which was characteristic of the rat P2X7R. Additional recordings showed that terminals showing sensitivity to the P2X7R-selective agonist, BzATP, were further inhibited by P2X7R selective antagonists, AZ10606120 and brilliant blue-G. In confocal micrographs from tissue sections and isolated terminals of the NH P2X7R-immunoreactivity was found to be localized in plasma membranes. Lastly, the role of P2X7R on AVP release was tested. Our results showed that BzATP evoked sustained AVP release in NH terminals, which was inhibited by AZ10606120. Taken together, our data lead us to conclude that the P2X7R is expressed in NH terminals and corroborates its role in AVP secretion.

  2. Functional expression of P2X7 receptors in non-neuronal cells of rat dorsal root ganglia.

    Science.gov (United States)

    Zhang, Xu-Feng; Han, Ping; Faltynek, Connie R; Jarvis, Michael F; Shieh, Char-Chang

    2005-08-02

    The P2X7 receptor is an ATP-sensitive ligand-gated cation channel, expressed predominantly in cells with immune origin. Recent studies have demonstrated that P2X7 may play an important role in pain signaling. In the present study, the expression of P2X7 receptors in non-neuronal cells and neurons isolated from dorsal root ganglia was characterized using patch clamp, pharmacological and confocal microscopy approaches. In small diameter DRG neurons, 100 microM 2', 3'-O-(4-benzoylbenzoyl)-ATP (BzATP) evoked an inward current, which was inhibited completely by 1 microM A-317491, a potent and selective P2X3 receptor antagonist. In contrast, BzATP evoked concentration-dependent increases in inward currents in non-neuronal DRG cells with an EC50 value of 26 +/- 0.14 microM, which were resistant to the blockade by A-317491. The activity to evoke cationic currents by P2X receptor agonists in non-neuronal cells showed a rank order of BzATP > ATP > alpha,beta-meATP. Pyridoxal-phosphate-6-azophenyl-,2',4'-disulphonic acid (PPADS) and Mg2+ produced concentration-dependent inhibition of BzATP-evoked currents in non-neuronal cells. Confocal microscopy revealed positive immunoreactivity of anti-P2X7 receptor antibodies on non-neuronal cells. No anti-P2X7 immunoreactivity was observed on DRG neurons. Further electrophysiological studies showed that prolonged agonist activation of P2X7 receptors in non-neuronal cells did not lead to cytolytic pore formation. Taken together, the present study demonstrated functional expression of P2X7 receptors in non-neuronal but not in small diameter neurons from rat DRG. Modulation of P2X7 receptors in non-neuronal cells might have impact on peripheral sensory transduction under normal and pathological states.

  3. Development of a Small Molecule P2X7R Antagonist as a Treatment for Acute SCI

    Science.gov (United States)

    2012-10-01

    Alexander disease. Ann Neurol 57:310–326. Liauw J, Hoang S, Choi M, Eroglu C, Sun GH, Percy M, Wildman-Tobriner B, Bliss T, Guzman RG, Barres BA...intercrossing to yield Aqp4−/− and Aqp4+/+ (WTs). For acute cortical slice experiments, we also used C57BL/6J pups from Jackson Laboratory as WT controls... Jackson Immunoresearch) were used at 1:250. After immunolabeling, the sections were counter- stained with DAPI (1:5,000, Invitrogen) for 10 min at room

  4. Development of a Small Molecule P2X7R Antagonist as a Treatment for Acute SCI

    Science.gov (United States)

    2013-10-01

    B., Goldman, S.A. Sustained induction of neuronal recruitment to the adult rat striatum by AAV4-delivered noggin and BDNF . Gene Therapy 19:483-93... stroke . Nature Medicine, 2014, in revision. Fox, I., Goldman, S.A., Huard, J., Kamp, T., Trucco, M. Pluripotential stem cells as therapy. Science

  5. Development of a Small Molecule P2X7R Antagonist as a Treatment for Acute SCI

    Science.gov (United States)

    2012-10-01

    Millipore). Secondary im- munochemistry of NG2 was performed using biotinylated anti-mouse IgG (1:200, 2 h at room temperature ). Tertiary staining used...streptavidin 568 (1:500, 1 h at room temperature ). Subsequent to NG2 staining, cells were washed and stained for -catenin (clone 14, 1:500; BD...ethyldeoxyuridine (EdU), and then immediately passaged using papain, fixed, and counted. We only pulsed for 4 h to eliminate cells going through mitosis more

  6. P2P Networking and Technology Enablers in Business Applications

    OpenAIRE

    Hariharan, Mahesh

    2006-01-01

    The usage of Peer to Peer Networks over the Internet has been growing by exponentially. Apartbfrom the hype surrounding P2P, it has remarkable ramifications on the way the Internet could be used. This is an area which is not explored as well as we would want to. This thesis examines the architectural differences in P2P networks and generic application domains where the principles of P2P are exploited. The usage of P2P in different business verticals and technology enablers that go along with ...

  7. P2P worm detection based on application identification

    Institute of Scientific and Technical Information of China (English)

    XIA Chunhe; SHI Yunping; LI Xiaojian; GAO Wei

    2007-01-01

    P2P worm exploits common vulnerabilities and spreads through peer-to-peer networks.Despite being recognized as a potential and deadly threat to the Internet recently,few relevant countermeasures are found in extant literature.Once it breaks out,a P2P worm could result in unpredictable losses.Based on propagation characteristics of the worm,this paper presents a detection method called PWD (P2P Worm Detection),which is designed based on application identification and unknown worm detection.Simulation result and LAN-environment experiment result both indicate that PWD is an effective method to detect and block P2P worms.

  8. Search by shortcuts in P2P scientific collaboration system

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A P2P scientific collaboration is a P2P network whose members can share documents, co-compile papers and codes, and communicate with each other instantly. From the simulation experiment we found that P2P collaboration system is a power-law network with a tail between -2 and -3.We utilized the algorithm that searches by high-degree shortcuts to improve the scalability of p2p collaboration system. The experimental result shows that the algorithm works better than random walk algorithm.

  9. P2P本质特征视角对P2P发展愿景的研究%The Research on P2P Development Vision from the Perspective of the Nature of P2P

    Institute of Scientific and Technical Information of China (English)

    陆岷峰; 李琴

    2015-01-01

    关于P2P,从产生到爆发性成长其争论之声从没停止过,由于对其认识上的不统一,导致对P2P的评价不一致,其发展目标、社会认同、成长方式及未来愿景也各不相同。从P2P本质特征分析入手,掌握P2P的基本特征,便于抓住事物的本质和主要矛盾,从而对P2P未来的发展前景作出科学的判断,对保持这一新生事物的发展才能提供一个良好的环境。 P2P其特征有本质和非本质之分,本质特征是“互联网+民间借贷”,非本质特征有互联网金融、信用中介、民间借贷等,P2P的本质特征已经充分表明其有美好的发展愿景,P2P有着巨大的需求市场和广泛的供给市场,同时也适应了金融市场多元化需求的大的发展趋势,现实中存在的问题是当前P2P所面临的监管、信任机制等不完善造成的,这并不否定P2P生命力及生存发展的本身。%The argument about P2P has never stopped from P2P’ emergence to its rapid growth. The different understanding to P2P leads to the different evaluation on P2P, and its development goals, social recognition, growth methods and future vision are also different. From the analysis on the nature of P2P, the paper thinks that mastering the basic features of P2P means mastering the essence and the principal contradiction of P2P, therefore the scientific judgment can be made on the development vision of P2P in the future, and a good environment can be provided to keep the development of the new-born thing. P2P is characterized with essential nature and non-essential nature, and its essential nature is“Internet+informal lending”, while the non-essential nature includes the Internet fi-nance, credit intermediary, informal lending etc. The essential nature of P2P has fully shown that P2P has a good development vision, has a huge market demand and a wide range of market supply, and has adapted to the development trend of the diversified

  10. P2X7 Receptors in Neurological and Cardiovascular Disorders

    Directory of Open Access Journals (Sweden)

    Stephen D. Skaper

    2009-01-01

    Full Text Available P2X receptors are ATP-gated cation channels that mediate fast excitatory transmission in diverse regions of the brain and spinal cord. Several P2X receptor subtypes, including P2X7, have the unusual property of changing their ion selectivity during prolonged exposure to ATP, which results in a channel pore permeable to molecules as large as 900 daltons. The P2X7 receptor was originally described in cells of hematopoietic origin, and mediates the influx of Ca2+ and Na+ and Ca2+ and Na+ ions as well as the release of proinflammatory cytokines. P2X7 receptors may affect neuronal cell death through their ability to regulate the processing and release of interleukin-1, a key mediator in neurodegeneration, chronic inflammation, and chronic pain. Activation of P2X7, a key mediator in neurodegeneration, chronic inflammation, and chronic pain. Activation of P2X7 receptors provides an inflammatory stimulus, and P2X7 receptor-deficient mice have substantially attenuated inflammatory responses, including models of neuropathic and chronic inflammatory pain. Moreover, P2X7 receptor activity, by regulating the release of proinflammatory cytokines, may be involved in the pathophysiology of depression. Apoptotic cell death occurs in a number of vascular diseases, including atherosclerosis, restenosis, and hypertension, and may be linked to the release of ATP from endothelial cells, P2X7 receptor activation, proinflammatory cytokine production, and endothelial cell apoptosis. In this context, the P2X7 receptor may be viewed as a gateway of communication between the nervous, immune, and cardiovascular systems.

  11. On {P2,Ci| i≥3 -covered Graphs%关于{P2, Ci| i≥3}-覆盖图

    Institute of Scientific and Technical Information of China (English)

    马润年

    2000-01-01

    Let G be a graph. If each edge of G belongs to a P2,Ci | i≥3 -factor, then graph G is called P2, Ci | i≥3-covered graph. In this paper, it is proved that a connected nonbipartitegraph G is a P2, Ci | i≥3 -covered graph if and only if i(G-S) |S|-1 for all S V(G), = S = V(G).%设G是一个图,若对于G的任意一边G都有P2, Ci | i≥3 -因子含有这条边,则称G是 P2, Ci| i≥3 -覆盖图.本文给出连通非二分图G是P2, Ci | i≥3 -覆盖图的充要条件为任给S V(G), V(G) = S = 有 i (G-S) |S|-1成立.

  12. Studies on antagonistic marine streptomycetes

    Digital Repository Service at National Institute of Oceanography (India)

    Chandramohan, D.; Nair, S.

    Sixty nine strains of Streptomyces sp. isolated from the sediments of Andaman and Nicobar islands (Bay of Bengal) were screened for their antagonistic property against a number of test cultures (Vibrio sp., Klebsiella sp., Escherichia coli, Shigella...

  13. Tanshinone II A sulfonate, but not tanshinone II A, acts as potent negative allosteric modulator of the human purinergic receptor P2X7.

    Science.gov (United States)

    Kaiser, M; Sobottka, H; Fischer, W; Schaefer, M; Nörenberg, W

    2014-09-01

    Tanshinone II A sulfonate (TIIAS) was identified as a potent, selective blocker of purinergic receptor P2X7 in a compound library screen. In this study, a detailed characterization of the pharmacologic effects of TIIAS on P2X7 is provided. Because TIIAS is a derivative of tanshinone II A (TIIA) and both compounds have been used interchangeably, TIIA was included in some assays. Fluorometric and electrophysiologic assays were used to characterize effects of TIIAS and TIIA on recombinantly expressed human, rat, and mouse P2X7. Results were confirmed in human monocyte-derived macrophages expressing native P2X7. In all experiments, involvement of P2X7 was verified using established P2X7 antagonists. TIIAS, but not TIIA, reduces Ca(2+) influx via human P2X7 (hP2X7) with an IC50 of 4.3 µM. TIIAS was less potent at mouse P2X7 and poorly inhibited rat P2X7. Monitoring of YO-PRO-1 uptake confirmed these findings, indicating that formation of the hP2X7 pore is also suppressed by TIIAS. Electrophysiologic experiments revealed a noncompetitive mode of action. TIIAS time-dependently inhibits hP2X7 gating, possibly by binding to the intracellular domain of the receptor. Inhibition of native P2X7 in macrophages by TIIAS was confirmed by monitoring Ca(2+) influx, YO-PRO-1 uptake, and release of the proinflammatory cytokine interleukin-1β. Fluorometric experiments involving recombinantly expressed rat P2X2 and human P2X4 were conducted and verified the compound's selectivity. Our data suggest that hP2X7 is a molecular target of TIIAS, but not of TIIA, a compound with different pharmacologic properties.

  14. P2P网络的应用与发展%The Application and Development of P2P Networking

    Institute of Scientific and Technical Information of China (English)

    张泊平

    2005-01-01

    P2P网络在短短的几年时间内迅速发展,并且已经深入到计算机网络的许多方面.从P2P网络的概念与分类,以及与客户机/服务器(C/S)模式比较入手,详细论述了P2P的应用以及目前存在的问题,指出了今后P2P发展的方向.

  15. P2微生物实验室的设计%Design on P2 Microbiology Laboratory

    Institute of Scientific and Technical Information of China (English)

    徐晓伟

    2012-01-01

    以一个P2微生物实验室的设计为例,介绍了P2微生物实验室的平面布局、维护结构、基本配置以及技术指标等。%Base on an example of P2 microbiology laboratory design,to briefly introduce the plane layout,maintenance of the structure,basic configuration of P2 microbiology laboratory,as well as technical indicators and so on.

  16. The role of P2X receptors in bone biology

    DEFF Research Database (Denmark)

    Jørgensen, N R; Syberg, S; Ellegaard, M

    2015-01-01

    come from studies on murine knockout models and from pharmacologic studies on cells and animals. More recently, the role of P2X receptors in human bone diseases has been documented. Loss-of-functions polymorphisms in the P2X7 receptorare associated with bone loss and increased fracture risk. Very...

  17. P2X7 receptors: channels, pores and more.

    Science.gov (United States)

    Volonté, C; Apolloni, S; Skaper, S D; Burnstock, G

    2012-09-01

    Purine nucleotides are well established as extracellular signaling molecules. P2X7 receptors (P2X7Rs) are members of the family of ionotropic ATP-gated receptors. Their activity can be found in a limited number of cell types, but is readily detectable in cells of hemopoietic lineage including macrophages, microglia, and certain lymphocytes, and mediates the influx of Ca2+ and Na+ as well as the release of pro-inflammatory cytokines. Amongst P2X receptors, P2X7Rs behave as a bifunctional molecule. The binding of ATP induces within milliseconds the opening of a channel selective for small cations, and within seconds a larger pore opens which allows permeation by molecules with a mass of up to 900 Da. In humans at least, the P2RX7 gene is highly polymorphic, and genetic differences within P2X7R affect receptor pore formation and channel function. ATP can act as a neurotransmitter, while the presence of P2X7Rs on immune cells suggests that they also regulate immune function and inflammatory responses. In addition, activation of the P2X7R has dramatic cytotoxic properties. The role of extracellular ATP and purinoceptors in cytokine regulation and neurological disorders is, in fact, the focus of a rapidly expanding area of research. P2X7Rs may affect neuronal cell death by regulating the processing and release of interleukin-1β, a key mediator in neurodegeneration, chronic inflammation, and chronic pain. Activation of P2X7Rs provides an inflammatory stimulus, and P2X7R-deficient mice display a marked attenuation of inflammatory responses, including models of neuropathic and chronic inflammatory pain. Moreover, P2X7R activity, by regulating the release of pro-inflammatory cytokines, may be involved in the pathophysiology of neuropsychiatric disorders. The P2X7R may thus represent a critical communication link between the nervous and immune systems, while providing a target for therapeutic exploitation. In this review we discuss current biology and pharmacology of the P2X

  18. The role of P2X receptors in bone biology

    DEFF Research Database (Denmark)

    Jørgensen, N R; Syberg, S; Ellegaard, M

    2015-01-01

    receptors regulate bone metabolism and especially for the P2X7 receptor an impressive amount of evidence has now documented its expression in osteoblasts, osteoclasts, and osteocytes as well as important functional roles in proliferation, differentiation, and function of the cells of bone. Key evidence has...... come from studies on murine knockout models and from pharmacologic studies on cells and animals. More recently, the role of P2X receptors in human bone diseases has been documented. Loss-of-functions polymorphisms in the P2X7 receptorare associated with bone loss and increased fracture risk. Very...... recently a report from a genetic study in multiple myeloma demonstrated that decreased P2X7 receptor function was associated with increased risk of developing multiple myeloma. In contrast, the risk of developing myeloma bone disease and subsequent vertebral fractures was increased in subjects carrying P2X...

  19. Effect of a corticotropin releasing hormone receptor antagonist on colonic sensory and motor function in patients with irritable bowel syndrome

    OpenAIRE

    2004-01-01

    Background and aims: Corticotropin releasing hormone (CRH) is a major mediator of the stress response in the brain-gut axis. Irritable bowel syndrome (IBS) is presumed to be a disorder of the brain-gut link associated with an exaggerated response to stress. We hypothesised that peripheral administration of α-helical CRH (αhCRH), a non-selective CRH receptor antagonist, would improve gastrointestinal motility, visceral perception, and negative mood in response to gut stimulation in IBS patient...

  20. Non-selective cation channels mediate chloroquine-induced relaxation in precontracted mouse airway smooth muscle.

    Directory of Open Access Journals (Sweden)

    Ting Zhang

    Full Text Available Bitter tastants can induce relaxation in precontracted airway smooth muscle by activating big-conductance potassium channels (BKs or by inactivating voltage-dependent L-type Ca2+ channels (VDLCCs. In this study, a new pathway for bitter tastant-induced relaxation was defined and investigated. We found nifedipine-insensitive and bitter tastant chloroquine-sensitive relaxation in epithelium-denuded mouse tracheal rings (TRs precontracted with acetylcholine (ACH. In the presence of nifedipine (10 µM, ACH induced cytosolic Ca2+ elevation and cell shortening in single airway smooth muscle cells (ASMCs, and these changes were inhibited by chloroquine. In TRs, ACH triggered a transient contraction under Ca2+-free conditions, and, following a restoration of Ca2+, a strong contraction occurred, which was inhibited by chloroquine. Moreover, the ACH-activated whole-cell and single channel currents of non-selective cation channels (NSCCs were blocked by chloroquine. Pyrazole 3 (Pyr3, an inhibitor of transient receptor potential C3 (TRPC3 channels, partially inhibited ACH-induced contraction, intracellular Ca2+ elevation, and NSCC currents. These results demonstrate that NSCCs play a role in bitter tastant-induced relaxation in precontracted airway smooth muscle.

  1. A reassessment of P2X7 receptor inhibition as a neuroprotective strategy in rat models of contusion injury.

    Science.gov (United States)

    Marcillo, Alexander; Frydel, Beata; Bramlett, Helen M; Dietrich, W Dalton

    2012-02-01

    These experiments were completed as part of an NIH "Facilities of Research Excellence in Spinal Cord Injury" contract to support independent replication of published studies that could be considered for eventual clinical testing. Recent studies have reported that selective inhibition of the P2X7 receptor improves both the functional and histopathological consequences of a contusive spinal cord injury (SCI) in rats. We repeated two published studies reporting the beneficial effects of pyridoxal-5'-phosphate-6-azophenyl-2'-4'-disulphonic acid (PPADS) or Brilliant blue G (BBG) treatment after SCI (Wang et al., 2004 and Peng et al., 2009). Mild thoracic SCI was first produced in Experiment 1 by means of the MASCIS impactor at T10 (height 6.25 mm, weight 10 g) followed by intraspinal administration of a P2X7 antagonist (2 μl/10 mM) after injury. Treatment with PPADS or another highly selective P2X7R antagonist Brilliant Blue G (BBG) (2 μl/02 mM) did not improve locomotive (BBB rating scale) over a 7 week period compared to vehicle treated rats. Also, secondary histopathological changes in terms of overall lesion and cavity volume were not significantly different between the PPADS, BBG, and vehicle treated animals. In the second experiment, the systemic administration of BBG (10 or 50 mg/kg, iv) 15 min, 24 and 72 h after moderate (12.5 mm) SCI failed to significantly improve motor recovery or histopathological outcome over the 6 week observational period. Although we cannot conclude that there will be no long-term beneficial effects in other spinal cord injury models using selective P2X7 receptor antagonists at different doses or treatment durations, we caution researchers that this potentially exciting therapy requires further preclinical investigations before the implementation of clinical trials targeting severe SCI patients. Copyright © 2011 Elsevier Inc. All rights reserved.

  2. The purinergic receptor P2X7 triggers alpha-secretase-dependent processing of the amyloid precursor protein.

    Science.gov (United States)

    Delarasse, Cécile; Auger, Rodolphe; Gonnord, Pauline; Fontaine, Bertrand; Kanellopoulos, Jean M

    2011-01-28

    The amyloid precursor protein (APP) is cleaved by β- and γ-secretases to generate the β-amyloid (Aβ) peptides, which are present in large amounts in the amyloid plaques of Alzheimer disease (AD) patient brains. Non-amyloidogenic processing of APP by α-secretases leads to proteolytic cleavage within the Aβ peptide sequence and shedding of the soluble APP ectodomain (sAPPα), which has been reported to be endowed with neuroprotective properties. In this work, we have shown that activation of the purinergic receptor P2X7 (P2X7R) stimulates sAPPα release from mouse neuroblastoma cells expressing human APP, from human neuroblastoma cells and from mouse primary astrocytes or neural progenitor cells. sAPPα shedding is inhibited by P2X7R antagonists or knockdown of P2X7R with specific small interfering RNA (siRNA) and is not observed in neural cells from P2X7R-deficient mice. P2X7R-dependent APP-cleavage is independent of extracellular calcium and strongly inhibited by hydroxamate-based metalloprotease inhibitors, TAPI-2 and GM6001. However, knockdown of a disintegrin and metalloproteinase-9 (ADAM9), ADAM10 and ADAM17 by specific siRNA, known to have α-secretase activity, does not block the P2X7R-dependent non-amyloidogenic pathway. Using several specific pharmacological inhibitors, we demonstrate that the mitogen-activated protein kinase modules Erk1/2 and JNK are involved in P2X7R-dependent α-secretase activity. Our study suggests that P2X7R, which is expressed in hippocampal neurons and glial cells, is a potential therapeutic target in AD.

  3. The Effect of Sympathetic Antagonists on the Antidepressant Action of Alprazolam

    Directory of Open Access Journals (Sweden)

    Gorash ZM

    2008-01-01

    Full Text Available Alprazolam is an anti-anxiety drug shown to be effective in the treatment of depression. In this study, the effect of sympathetic receptor antagonists on alprazolam–induced antidepressant action was studied using a mouse model of forced swimming behavioral despair. The interaction of three sympathetic receptor antagonists with benzodiazepines, which may impact the clinical use of alprazolam, was also studied. Behavioral despair was examined in six groups of albino mice. Drugs were administered intraperitoneally. The control group received only a single dose of 1% Tween 80. The second group received a single dose of alprazolam, and the third group received an antagonist followed by alprazolam. The fourth group was treated with imipramine, and the fifth group received an antagonist followed by imipramine. The sixth group was treated with a single dose of an antagonist alone (atenolol, a β1-selective adrenoceptor antagonist; propranolol, a non selective β-adrenoceptor antagonist; and prazocin, an α1-adrenoceptor antagonist. Results confirmed the antidepressant action of alprazolam and imipramine. Prazocin treatment alone produced depression, but it significantly potentiated the antidepressant actions of imipramine and alprazolam. Atenolol alone produced an antidepressant effect and potentiated the antidepressant action of alprazolam. Propranolol treatment alone produced depression, and antagonized the effects of alprazolam and imipramine, even producing depression in combined treatments. In conclusion, our results reveal that alprazolam may produce antidepressant effects through the release of noradrenaline, which stimulates β2 receptors to produce an antidepressant action. Imipramine may act by activating β2 receptors by blocking or down-regulating β1 receptors.

  4. Evaluation of P2-C2 bias estimation

    Science.gov (United States)

    Santos, M. C.; van der Bree, R.; van der Marel, H.; Verhagen, S.; Garcia, C. A.

    2010-12-01

    The availability of the second civilian code C2 created a new issue to be considered: the bias relating P2 and C2 signals. Such an issue is important when merging C2-capable and legacy receivers and when processing data collected by a C2-capable receiver with satellite clock values generated using a legacy receiver network. The P2-C2 bias is essentially a consequence from the fact that receiver and satellite hardware delays for C2 measurements may not be necessarily the same of those for P2. Knowing this bias makes possible the use of C2 as an observable for positioning using IGS clock products. We are using the PPP-based approach for P2-C2 bias estimation developed at the University of New Brunswick. For that purpose, we use GAPS, the GPS Analysis and Positioning Software. We also determine P2-C2 bias directly from the code observations. This poster presents and discusses the evaluation of P2-C2 values estimated from a sub-set of the IGS L2C Test Network. The values are applied to observations collected by C2-capable receivers in the point positioning mode. Coordinate repeatability indicate an improvement of up to 50% when using the P2-C2 bias.

  5. Queries mining for efficient routing in P2P communities

    CERN Document Server

    Ismail, Anis; Durand, Nicolas; Nachouki, Gilles; Hajjar, Mohammad

    2011-01-01

    Peer-to-peer (P2P) computing is currently attracting enormous attention. In P2P systems a very large number of autonomous computing nodes (the peers) pool together their resources and rely on each other for data and services. Peer-to-peer (P2P) Data-sharing systems now generate a significant portion of Internet traffic. Examples include P2P systems for network storage, web caching, searching and indexing of relevant documents and distributed network-threat analysis. Requirements for widely distributed information systems supporting virtual organizations have given rise to a new category of P2P systems called schema-based. In such systems each peer exposes its own schema and the main objective is the efficient search across the P2P network by processing each incoming query without overly consuming bandwidth. The usability of these systems depends on effective techniques to find and retrieve data; however, efficient and effective routing of content-based queries is a challenging problem in P2P networks. This wo...

  6. P2MP MPLS-Based Hierarchical Service Management System

    Science.gov (United States)

    Kumaki, Kenji; Nakagawa, Ikuo; Nagami, Kenichi; Ogishi, Tomohiko; Ano, Shigehiro

    This paper proposes a point-to-multipoint (P2MP) Multi-Protocol Label Switching (MPLS) based hierarchical service management system. Traditionally, general management systems deployed in some service providers control MPLS Label Switched Paths (LSPs) (e.g., RSVP-TE and LDP) and services (e.g., L2VPN, L3VPN and IP) separately. In order for dedicated management systems for MPLS LSPs and services to cooperate with each other automatically, a hierarchical service management system has been proposed with the main focus on point-to-point (P2P) TE LSPs in MPLS path management. In the case where P2MP TE LSPs and services are deployed in MPLS networks, the dedicated management systems for P2MP TE LSPs and services must work together automatically. Therefore, this paper proposes a new algorithm that uses a correlation between P2MP TE LSPs and multicast VPN services based on a P2MP MPLS-based hierarchical service management architecture. Also, the capacity and performance of the proposed algorithm are evaluated by simulations, which are actually based on certain real MPLS production networks, and are compared to that of the algorithm for P2P TE LSPs. Results show this system is very scalable within real MPLS production networks. This system, with the automatic correlation, appears to be deployable in real MPLS production networks.

  7. P2Y2 and P2Y4 receptors regulate pancreatic Ca²+-activated K+ channels differently

    DEFF Research Database (Denmark)

    Klærke, Susanne Edeling Hede; Amstrup, Jan; Klærke, Dan Arne;

    2005-01-01

    Extracellular ATP is an important regulator of transepithelial transport in a number of tissues. In pancreatic ducts, we have shown that ATP modulates epithelial K+ channels via purinergic receptors, most likely the P2Y2 and P2Y4 receptors, but the identity of the involved K+ channels was not clear....... In this study, we show by RT-PCR analysis that rat pancreatic ducts express Ca(2+)-activated K+ channels of intermediate conductance (IK) and big conductance (BK), but not small conductance (SK). Possible interactions between P2Y receptors and these Ca(2+)-activated K+ channels were examined in co......-expression experiments in Xenopus laevis oocytes. K+ channel activity was measured electrophysiologically in oocytes stimulated with UTP (0.1 mM). UTP stimulation of oocytes expressing P2Y4 receptors and BK channels resulted in a 30% increase in the current through the expressed channels. In contrast, stimulation of P2Y...

  8. Melittin Modulates Keratinocyte Function through P2 Receptor-dependent ADAM Activation*

    Science.gov (United States)

    Sommer, Anselm; Fries, Anja; Cornelsen, Isabell; Speck, Nancy; Koch-Nolte, Friedrich; Gimpl, Gerald; Andrä, Jörg; Bhakdi, Sucharit; Reiss, Karina

    2012-01-01

    Melittin, the major component of the bee venom, is an amphipathic, cationic peptide with a wide spectrum of biological properties that is being considered as an anti-inflammatory and anti-cancer agent. It modulates multiple cellular functions but the underlying mechanisms are not clearly understood. Here, we report that melittin activates disintegrin-like metalloproteases (ADAMs) and that downstream events likely contribute to the biological effects evoked by the peptide. Melittin stimulated the proteolysis of ADAM10 and ADAM17 substrates in human neutrophil granulocytes, endothelial cells and murine fibroblasts. In human HaCaT keratinocytes, melittin induced shedding of the adhesion molecule E-cadherin and release of TGF-α, which was accompanied by transactivation of the EGF receptor and ERK1/2 phosphorylation. This was followed by functional consequences such as increased keratinocyte proliferation and enhanced cell migration. Evidence is provided that ATP release and activation of purinergic P2 receptors are involved in melittin-induced ADAM activation. E-cadherin shedding and EGFR phosphorylation were dose-dependently reduced in the presence of ATPases or P2 receptor antagonists. The involvement of P2 receptors was underscored in experiments with HEK cells, which lack the P2X7 receptor and showed strikingly increased response to melittin stimulation after transfection with this receptor. Our study provides new insight into the mechanism of melittin function which should be of interest particularly in the context of its potential use as an anti-inflammatory or anti-cancer agent. PMID:22613720

  9. Distributed Frequent Item Sets Mining over P2P Networks

    OpenAIRE

    Zahra Farzanyar; Mohammadreza Kangavari

    2015-01-01

    Data intensive peer-to-peer (P2P) networks are becoming increasingly popular in applications like social networking, file sharing networks, etc. Data mining in such P2P environments is the new generation of advanced P2P applications. Unfortunately, most of the existing data mining algorithms do not fit well in such environments since they require data that can be accessed in its entirety. It also is not easy due to the requirements of online transactional data streams. In this paper, we have ...

  10. The role of P2X receptors in bone biology

    DEFF Research Database (Denmark)

    Jørgensen, N R; Syberg, S; Ellegaard, M

    2015-01-01

    receptors regulate bone metabolism and especially for the P2X7 receptor an impressive amount of evidence has now documented its expression in osteoblasts, osteoclasts, and osteocytes as well as important functional roles in proliferation, differentiation, and function of the cells of bone. Key evidence has...... come from studies on murine knockout models and from pharmacologic studies on cells and animals. More recently, the role of P2X receptors in human bone diseases has been documented. Loss-of-functions polymorphisms in the P2X7 receptorare associated with bone loss and increased fracture risk. Very...

  11. Increasing Structured P2P Protocol Resilience to Localized Attacks

    OpenAIRE

    Germanus, Daniel

    2015-01-01

    The Peer-to-Peer (P2P) computing model has been applied to many application fields over the last decade. P2P protocols made their way from infamous - and frequently illicit - file sharing applications towards serious applications, e.g., in entertainment, audio/video conferencing, or critical applications like smart grid, Car-2-Car communication, or Machine-to-Machine communication. Some of the reasons for that are P2P's decentralized design that inherently provides for fault tolerance to non-...

  12. Code wars 10 years of P2P software litigation

    CERN Document Server

    Giblin, Rebecca

    2011-01-01

    Code Wars recounts the legal and technological history of the first decade of the P2P file sharing era, focusing on the innovative and anarchic ways in which P2P technologies evolved in response to decisions reached by courts with regard to their predecessors. With reference to US, UK, Canadian and Australian secondary liability regimes, this insightful book develops a compelling new theory to explain why a decade of ostensibly successful litigation failed to reduce the number, variety or availability of P2P file sharing applications - and highlights ways the law might need to change if it is

  13. Comparing Pedophile Activity in Different P2P Systems

    OpenAIRE

    Raphaël Fournier; Thibault Cholez; Matthieu Latapy; Isabelle Chrisment; Clémence Magnien; Olivier Festor; Ivan Daniloff

    2014-01-01

    International audience; Peer-to-peer (P2P) systems are widely used to exchange content over the Internet. Knowledge of pedophile activity in such networks remains limited, despite having important social consequences. Moreover, though there are different P2P systems in use, previous academic works on this topic focused on one system at a time and their results are not directly comparable. We design a methodology for comparing KAD and eDonkey, two P2P systems among the most prominent ones and ...

  14. 松下P2和HD新锐

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    NAB2005上,松下电器展出了以P2和HD为核心的最新产品,以工作流程为主线展示了P2和HD通过USB、IEEE1394连接全流程的工作模式,采用P2为记录媒体的HD图像采集领域掀起热潮。在新闻采集和节目制作市场,松下着重建立DVCPRO以及DVCPRO 50图像采集的模式。下面介绍几款采用P2卡的HD图像采集新品。

  15. Crystal structure of the bacteriophage P2 integrase catalytic domain.

    Science.gov (United States)

    Skaar, Karin; Claesson, Magnus; Odegrip, Richard; Högbom, Martin; Haggård-Ljungquist, Elisabeth; Stenmark, Pål

    2015-11-30

    Bacteriophage P2 is a temperate phage capable of integrating its DNA into the host genome by site-specific recombination upon lysogenization. Integration and excision of the phage genome requires P2 integrase, which performs recognition, cleavage and joining of DNA during these processes. This work presents the high-resolution crystal structure of the catalytic domain of P2 integrase, and analysis of the structure-function relationship of several previously identified non-functional P2 integrase mutants. The DNA binding area is characterized by a large positively charged patch, harboring key residues. The structure reveals potential for large dimer flexibility, likely essential for rearrangement of DNA strands upon integration and excision of the phage DNA.

  16. The role of P2X receptors in bone biology

    DEFF Research Database (Denmark)

    Jørgensen, Niklas Rye; Syberg, S; Ellegaard, M

    2015-01-01

    Bone is a highly dynamic organ, being constantly modeled and remodeled in order to adapt to the changing need throughout life. Bone turnover involves the coordinated actions of bone formation and bone degradation. Over the past decade great effort has been put into the examination of how P2X...... receptors regulate bone metabolism and especially for the P2X7 receptor an impressive amount of evidence has now documented its expression in osteoblasts, osteoclasts, and osteocytes as well as important functional roles in proliferation, differentiation, and function of the cells of bone. Key evidence has...... come from studies on murine knockout models and from pharmacologic studies on cells and animals. More recently, the role of P2X receptors in human bone diseases has been documented. Loss-of-functions polymorphisms in the P2X7 receptorare associated with bone loss and increased fracture risk. Very...

  17. Manipulation of P2X Receptor Activities by Light Stimulation

    Directory of Open Access Journals (Sweden)

    Sang Seong Kim

    2016-01-01

    Full Text Available P2X receptors are involved in amplification of inflammatory responses in peripheral nociceptive fibers and in mediating pain-related signals to the CNS. Control of P2X activation has significant importance in managing unwanted hypersensitive neuron responses. To overcome the limitations of chemical ligand treatment, optical stimulation methods of optogenetics and photoswitching achieve efficient control of P2X activation while allowing specificity at the target site and convenient stimulation by light illumination. There are many potential applications for photosensitive elements, such as improved uncaging methods, photoisomerizable ligands, photoswitches, and gold nanoparticles. Each technique has both advantages and downsides, and techniques are selected according to the purpose of the application. Technical advances not only provide novel approaches to manage inflammation or pain mediated by P2X receptors but also suggest a similar approach for controlling other ion channels.

  18. TCLM-P2P: Task Collaboration Logic Model Oriented to P2P Community%TCLM-P2P:面向P2P社区的任务协作逻辑模型

    Institute of Scientific and Technical Information of China (English)

    王杨; 王汝传; 严远亭; 韩志杰; 赵保华

    2012-01-01

    P2P网络中广泛存在的“free riding”现象使其在任务协作领域的应用受到了极大制约.为了实现P2P网络环境下的有效任务协作,提出了一种具有激励机制的任务协作逻辑模型.基于Agent理论,首先给出了对等体、半对等体、P2P社区等概念;然后在合同网的框架下提出了面向P2P网络社区的任务协作逻辑模型TCLM-P2P(task collaborative logic model oriented to P2P community).相对于传统的任务协作模型,在合理的前提假设条件下,模型给出了模型公理和协作规则.该模型通过基于虚拟积分的协作算法实现了具有激励机制的P2P网络中的任务分配与协作.原型系统的实现及仿真实验结果表明TCLM-P2P模型具有可行性和有效性:不仅能够激励自利节点主动参与到任务分配与协作中;同时也能在一定程度上抑制节点的free riding行为,从而保障了P2P系统的有序工作.%Traditional P2P networks mainly are applied to file sharing and instant message fields. However, how to perform the task collaboration based on P2P community is a challenging job. The former research work indicated that the task collaboration in P2P network had been greatly restricted by free riding behaviors. To realize effective task allocating and task collaborating in P2P network environment, this paper presents a task collaboration logic model oriented to P2P community. Based on agent and multi-agent theory, the paper firstly introduces some concepts including the peer body, half-peer body and P2P community; then the TCLM-P2P is presented including some collaboration axioms and rulers. In order to enhance the incentive mechanism, virtual score becomes the main goal which each peer endeavor pursues. In addition, based on the contract net protocol, a task collaboration algorithm is presented. The proposed algorithm is composed of two phases. One is the task collaboration and the other is the task second bid when some peers fail

  19. Control of bone development by P2X and P2Y receptors expressed in mesenchymal and hematopoietic cells

    Science.gov (United States)

    Lenertz, Lisa Y.; Baughman, Cory J.; Waldschmidt, Noelle V.; Thaler, Roman; van Wijnen, Andre J.

    2015-01-01

    Bone development and homeostasis require the interplay between several cell types, including mesenchymal osteoblasts and osteocytes, as well as hematopoietic osteoclasts. Recent evidence suggests that cell proliferation, differentiation and apoptosis of both mesenchymal and hematopoietic stem cells, which are fundamental for tissue regeneration and treatment of degenerative diseases, is controlled by P2 receptors (i.e., P2X and P2Y receptors). Both types of P2 receptors are versatile transducers of diverse signals activated by extracellular nucleotides like ATP that are released in response to tissue injury, infection or shear stress. The P2X family of receptors has been shown to mediate multiple signaling events including the influx of calcium, activation of mitogen activated protein kinases (MAPKs) and induction of AP-1 family members known to regulate bone development. Support for the significance of P2X7 in regulating bone development and homeostasis has been provided by several studies focusing on animal models and single nucleotide polymorphisms. P2 receptors are functionally expressed in both bone forming osteoblasts and bone resorbing osteoclasts, while recent findings also suggest that these receptors translate mechanical stimuli in osteocytes. Their ability to respond to external nucleotide analogs renders these cell surface proteins excellent targets for skeletal regenerative therapies. This overview summarizes mechanisms by which nucleotide receptors control skeletal cells and contribute to bone tissue development remodeling and repair. PMID:26079571

  20. P2 receptor-mediated signaling in mast cell biology

    OpenAIRE

    Bulanova, Elena; Bulfone-Paus, Silvia

    2009-01-01

    Mast cells are widely recognized as effector cells of allergic inflammatory reactions. They contribute to the pathogenesis of different chronic inflammatory diseases, wound healing, fibrosis, thrombosis/fibrinolysis, and anti-tumor immune responses. In this paper, we summarized the role of P2X and P2Y receptors in mast cell activation and effector functions. Mast cells are an abundant source of ATP which is stored in their granules and secreted upon activation. We discuss the contribution of ...

  1. The Physical Mirror Equivalence for the Local P^2

    CERN Document Server

    Cacciatori, Sergio Luigi; Guerra, Stefano

    2013-01-01

    In this paper we consider the total space of the canonical bundle of P^2 and we use a proposal by Hosono, together with results in Seidel and Auroux-Katzarkov-Orlov, to deduce the right physical mirror equivalence between D^b(K_{P^2}) and the derived Fukaya category of its mirror. By construction, our equivalence is compatible with the mirror map between moduli spaces and with the computation of Gromov--Witten invariants.

  2. Accelerated FoxP2 evolution in echolocating bats.

    Directory of Open Access Journals (Sweden)

    Gang Li

    Full Text Available FOXP2 is a transcription factor implicated in the development and neural control of orofacial coordination, particularly with respect to vocalisation. Observations that orthologues show almost no variation across vertebrates yet differ by two amino acids between humans and chimpanzees have led to speculation that recent evolutionary changes might relate to the emergence of language. Echolocating bats face especially challenging sensorimotor demands, using vocal signals for orientation and often for prey capture. To determine whether mutations in the FoxP2 gene could be associated with echolocation, we sequenced FoxP2 from echolocating and non-echolocating bats as well as a range of other mammal species. We found that contrary to previous reports, FoxP2 is not highly conserved across all nonhuman mammals but is extremely diverse in echolocating bats. We detected divergent selection (a change in selective pressure at FoxP2 between bats with contrasting sonar systems, suggesting the intriguing possibility of a role for FoxP2 in the evolution and development of echolocation. We speculate that observed accelerated evolution of FoxP2 in bats supports a previously proposed function in sensorimotor coordination.

  3. Data Sharing in DHT Based P2P Systems

    Science.gov (United States)

    Roncancio, Claudia; Del Pilar Villamil, María; Labbé, Cyril; Serrano-Alvarado, Patricia

    The evolution of peer-to-peer (P2P) systems triggered the building of large scale distributed applications. The main application domain is data sharing across a very large number of highly autonomous participants. Building such data sharing systems is particularly challenging because of the “extreme” characteristics of P2P infrastructures: massive distribution, high churn rate, no global control, potentially untrusted participants... This article focuses on declarative querying support, query optimization and data privacy on a major class of P2P systems, that based on Distributed Hash Table (P2P DHT). The usual approaches and the algorithms used by classic distributed systems and databases for providing data privacy and querying services are not well suited to P2P DHT systems. A considerable amount of work was required to adapt them for the new challenges such systems present. This paper describes the most important solutions found. It also identifies important future research trends in data management in P2P DHT systems.

  4. P2P Data Management in Mobile Wireless Sensor Network

    Directory of Open Access Journals (Sweden)

    Nida Sahar Sayeda

    2013-04-01

    Full Text Available The rapid growth in wireless technologies has made wireless communication an important source for transporting data across different domains. In the same way, there are possibilities of many potential applications that can be deployed using WSNs (Wireless Sensor Networks. However, very limited applications are deployed in real life due to the uncertainty and dynamics of the environment and scare resources. This makes data management in WSN a challenging area to find an approach that suits its characteristics. Currently, the trend is to find efficient data management schemes using evolving technologies, i.e. P2P (Peer-to-Peer systems. Many P2P approaches have been applied in WSNs to carry out the data management due to similarities between WSN and P2P. With the similarities, there are differences too that makes P2P protocols inefficient in WSNs. Furthermore, to increase the efficiency and to exploit the delay tolerant nature of WSNs, where ever possible, the mobile WSNs are gaining importance. Thus, creating a three dimensional problem space to consider, i.e. mobility, WSNs and P2P. In this paper, an efficient algorithm is proposed for data management using P2P techniques for mobile WSNs. The real world implementation and deployment of proposed algorithm is also presented

  5. Network Awareness in P2P-TV Applications

    Science.gov (United States)

    Traverso, Stefano; Leonardi, Emilio; Mellia, Marco; Meo, Michela

    The increasing popularity of applications for video-streaming based on P2P paradigm (P2P-TV) is raising the interest of both broadcasters and network operators. The former see a promising technology to reduce the cost of streaming content over the Internet, while offering a world-wide service. The latter instead fear that the traffic offered by these applications can grow without control, affecting other services, and possibly causing network congestion and collapse. The “Network-Aware P2P-TV Application over Wise Networks” FP7 project aims at studying and developing a novel P2P-TV application offering the chance to broadcast high definition video to broadcasters and to carefully manage the traffic offered by peers to the network, therefore avoiding worries to Internet providers about network overload. In such context, we design a simulator to evaluate performance of different P2P-TV solutions, to compare them both considering end-users’ and network providers’ perspectives, such as quality of service perceived by subscribers and link utilization. In this paper, we provide some results that show how effective can be a network aware P2P-TV system.

  6. Improving P2P live-content delivery using SVC

    Science.gov (United States)

    Schierl, T.; Sánchez, Y.; Hellge, C.; Wiegand, T.

    2010-07-01

    P2P content delivery techniques for video transmission have become of high interest in the last years. With the involvement of client into the delivery process, P2P approaches can significantly reduce the load and cost on servers, especially for popular services. However, previous studies have already pointed out the unreliability of P2P-based live streaming approaches due to peer churn, where peers may ungracefully leave the P2P infrastructure, typically an overlay networks. Peers ungracefully leaving the system cause connection losses in the overlay, which require repair operations. During such repair operations, which typically take a few roundtrip times, no data is received from the lost connection. While taking low delay for fast-channel tune-in into account as a key feature for broadcast-like streaming applications, the P2P live streaming approach can only rely on a certain media pre-buffer during such repair operations. In this paper, multi-tree based Application Layer Multicast as a P2P overlay technique for live streaming is considered. The use of Flow Forwarding (FF), a.k.a. Retransmission, or Forward Error Correction (FEC) in combination with Scalable video Coding (SVC) for concealment during overlay repair operations is shown. Furthermore the benefits of using SVC over the use of AVC single layer transmission are presented.

  7. Characterization of P2P IPTV Traffic: Scaling Analysis

    CERN Document Server

    Silverston, Thomas; Salamatian, Kave

    2007-01-01

    P2P IPTV applications arise on the Internet and will be massively used in the future. It is expected that P2P IPTV will contribute to increase the overall Internet traffic. In this context, it is important to measure the impact of P2P IPTV on the networks and to characterize this traffic. During the 2006 FIFA World Cup, we performed an extensive measurement campaign. We measured network traffic generated by broadcasting soccer games by the most popular P2P IPTV applications, namely PPLive, PPStream, SOPCast and TVAnts. From the collected data, we characterized the P2P IPTV traffic structure at different time scales. To the best of our knowledge, this is the first work, which presents a complete multiscale analysis of the P2P IPTV traffic. Our observations show that the network traffic has not the same scale behavior whether the applications use TCP or UDP. For all the applications, the download traffic is different from the upload traffic and the signaling traffic has an impact on the download traffic.

  8. Potential energy curves for P2 and P2+ constructed from a strictly N-representable natural orbital functional

    CERN Document Server

    Piris, Mario

    2016-01-01

    The potential energy curves of P2 and P2+ have been calculated using an approximate, albeit strictly N-representable, energy functional of the one-particle reduced density matrix: PNOF5. Quite satisfactory accord is found for the equilibrium bond lengths and dissociation energies for both species. The predicted vertical ionization energy for P2 by means of the extended Koopmans' theorem is 10.57 eV in good agreement with the experimental data. Comparison of the vibrational energies and anharmonicities with their corresponding experimental values supports the quality of the resultant potential energy curves.

  9. Central sensitization of nociceptive neurons in rat medullary dorsal horn involves purinergic P2X7 receptors.

    Science.gov (United States)

    Itoh, K; Chiang, C-Y; Li, Z; Lee, J-C; Dostrovsky, J O; Sessle, B J

    2011-09-29

    Central sensitization is a crucial process underlying the increased neuronal excitability of nociceptive pathways following peripheral tissue injury and inflammation. Our previous findings have suggested that extracellular adenosine 5'-triphosphate (ATP) molecules acting at purinergic receptors located on presynaptic terminals (e.g., P2X2/3, P2X3 subunits) and glial cells are involved in the glutamatergic-dependent central sensitization induced in medullary dorsal horn (MDH) nociceptive neurons by application to the tooth pulp of the inflammatory irritant mustard oil (MO). Since growing evidence indicates that activation of P2X7 receptors located on glia is involved in chronic inflammatory and neuropathic pain, the aim of the present study was to test in vivo for P2X7 receptor involvement in this acute inflammatory pain model. Experiments were carried out in anesthetized Sprague-Dawley male rats. Single unit recordings were made in MDH functionally identified nociceptive neurons for which mechanoreceptive field, mechanical activation threshold and responses to noxious stimuli were tested. We found that continuous intrathecal (i.t.) superfusion over MDH of the potent P2X7 receptor antagonists brilliant blue G and periodated oxidized ATP could each significantly attenuate the MO-induced MDH central sensitization. MDH central sensitization could also be produced by i.t. superfusion of ATP and even more effectively by the P2X7 receptor agonist benzoylbenzoyl ATP. Superfusion of the microglial blocker minocycline abolished the MO-induced MDH central sensitization, consistent with reports that dorsal horn P2X7 receptors are mostly expressed on microglia. In control experiments, superfusion over MDH of vehicle did not produce any significant changes. These novel findings suggest that activation of P2X7 receptors in vivo may be involved in the development of central sensitization in an acute inflammatory pain model.

  10. P2X7 Receptor Mediates Spinal Microglia Activation of Visceral Hyperalgesia in a Rat Model of Chronic Pancreatitis.

    Science.gov (United States)

    Liu, Pei-Yi; Lee, I-Hui; Tan, Ping-Heng; Wang, Yen-Po; Tsai, Chia-Fen; Lin, Han-Chieh; Lee, Fa-Yauh; Lu, Ching-Liang

    2015-11-01

    Molecular mechanisms underlying the activated spinal microglia in association with the pain in chronic pancreatitis (CP) remain unknown. We tested whether P2X7R on spinal microglia mediates the pathogenesis of visceral pain using a CP rat model. The CP model was induced via intraductal injection of 2% trinitrobenzene sulfonic acid into male Sprague-Dawley rats. Hyperalgesia was assessed based on the mechanical sensitivity to Von-Frey filaments (VFFs), and nocifensive behaviors were measured in response to electrical stimulation of the pancreas. Three weeks after CP induction, spinal cord samples were harvested for immunostaining, immunoblot, and real-time polymerase chain reaction analyses of the P2X7R. Changes in nocifensive behaviors and associated molecular effectors were assessed by blocking spinal cord P2X7R pharmacologically using the selective P2X7R antagonist brilliant blue G (BBG) or genetically using short interfering RNA (siRNA). CP induced a significant up-regulation of spinal P2X7R expression, which colocalized with a microglial marker (OX-42). Intrathecal administration of BBG significantly attenuated CP-related visceral hyperalgesia in response to VFF-mediated or electrical stimulation of the pancreas, which was associated with suppressed spinal expression of P2X7R and inhibited activation of spinal microglia. Intrathecal injection of siRNA to knock down P2X7R expression in the spinal cord would suppress the nociceptive behaviors in CP rats. Spinal microglia P2X7R mediates central sensitization of chronic visceral pain in CP. BBG may represent an effective drug for the treatment of chronic pain in CP patients.

  11. Leukotriene B4 modulates P2X7 receptor-mediated Leishmania amazonensis elimination in murine macrophages.

    Science.gov (United States)

    Chaves, Mariana M; Marques-da-Silva, Camila; Monteiro, Ana Paula T; Canetti, Cláudio; Coutinho-Silva, Robson

    2014-05-15

    ATP is an important signaling molecule in the immune system, and it is able to bind the P2X7 purinergic receptor. Recently, our group showed that ATP-treated macrophages eliminate Leishmania amazonensis. It has been reported that leukotriene B4 (LTB4) reduces the parasitic load of infected macrophages. Additionally, it has been demonstrated that the P2X7 receptor can induce PLA2 activation and arachidonic acid mobilization. Based on these findings, we investigated whether LTB4 is produced upon P2X7 receptor activation and examined whether LTB4 modulates parasite elimination. Using macrophages lacking the P2X7 receptor, we observed that ATP was not able to reduce L. amazonensis load. This result suggests a role of the P2X7 purinergic receptor in parasite elimination. In addition, ATP was sufficient to induce LTB4 release from infected control macrophages but not from macrophages lacking the P2X7 receptor. Moreover, we found that ATP failed to decrease the parasitic load in 5-lipoxygenase (LO)-deficient macrophages. Treatment with the 5-LO inhibitor AA861 also impairs the ATP effect on parasitic loads. Furthermore, macrophages from 5-LO knockout mice eliminated L. amazonensis in the presence of exogenous LTB4, and macrophages obtained from P2X7 receptor knockout mice eliminated L. amazonensis when incubated with ionomycin. Finally, we demonstrated that in the presence of CP105696, an antagonist for LTB4 high-affinity receptor, ATP was not able to reduce parasitic load. These results indicate that P2X7 receptor activation leads to LTB4 formation, which is required for L. amazonensis elimination.

  12. Effect of Electroacupuncture at Hegu (LI 4) on P2X2 and P2X3 Receptors in Trigeminal Ganglion in Pulpalgia Rats%电针合谷穴对实验性牙髓痛大鼠三叉神经节P2X2、P2X3受体的影响

    Institute of Scientific and Technical Information of China (English)

    陈莉; 张英; 严琴; 乐凯

    2015-01-01

    RNA表达量明显低于E组(P<0.01)。结论 LPS诱导大鼠牙髓痛时,三叉神经节P2X2、P2X3受体蛋白表达量增加。电针合谷穴和注射A-317491均可降低LPS诱导牙髓痛大鼠P2X2、P2X3受体mRNA表达,这可能是电针合谷穴镇痛的机制。%Objective To explore the effect of electroacupuncture at Hegu (LI 4) on the expressions of P2X2 and P2X3 receptors in experimental pulpalgia rats.Method Forty-two male SD rats were randomized into a normal group (group N), a control group (group C), a pulpalgia model group (group M), an antagonist group (group A), an electroacupuncture group (group E), and an antagonist+electroacupuncture group (group AE), 7 rats in each group. Group N didn’t receive any interventions; group C received injection of normal saline into pulp cavity of the same dose as the injection in group M, and the cavity was then blocked by dental fillings 5-6 min later; in group M, maxillary first and second molar teeth were drilled (drill bit of 1 mm in diameter) to expose pulp and lipopolysaccharide (LPS) solution 5μg/μL was injected into the holes (1~3μL for each hole), and the holes were then covered by dental fillings 5-6 min later; group A received the same modeling method as that in group M, but A-317491 was injected together with LPS (0.5 mg/kg); group E received electroacupuncture at bilateral Hegu (LI 4) with needles retained for 30 min, once a day, totally for 3 times; group AE received the same electroacupuncture intervention after receiving the same treatments as that in group A. The rats’ behaviors and weight were observed for 30 min after intervention each day. The rats were sacrificed on the 4th day, and the mRNA expressions of P2X2 and P2X3 receptors andβ-actin in trigeminal ganglion were detected by using RT-PCR. The mRNA expressions were then compared among the groups.Result The behavioral changes in group M, E, and AE were more significant than that in group C and N (P<0.01); the behavioral changes in group A, E, and AE were less

  13. The novel heteromeric bivalent ligand SB9 potently antagonizes P2Y(1) receptor-mediated responses.

    Science.gov (United States)

    Lambrecht, G; Ganso, M; Bäumert, H G; Spatz-Kümbel, G; Hildebrandt, C; Braun, K; Mutschler, E

    2000-07-01

    Effects of 6-[(4,6,8-trisulfo-1-naphthyl)iminocarbonyl-1, 3-(4-methylphenylene)iminocarbonyl-1, 3-phenylene-azo]-pyridoxal-5'-phosphate (SB9), a heterodimeric bivalent ligand consisting of pyridoxal-5'-phosphate and the suramin monomer, were studied on contractions of the rat vas deferens elicited by alpha beta-methylene ATP (alpha beta meATP; mediated by P2X(1)-like receptors), contractions of the guinea-pig ileal longitudinal smooth muscle elicited by adenosine 5'-O-(2-thiodiphosphate) (ADP beta S mediated by P2Y(1)-like receptors), and the degradation of ATP by ecto-nucleotidases in folliculated Xenopus laevis oocytes. SB9 (0.1-10 microM) antagonized contractile responses produced by alpha beta meATP or ADP beta S in a concentration-dependent manner. Schild analysis yielded linear regression lines of unit slope, indicating competitive antagonism. From the rightward shifts of the agonist concentration-response curves pA(2) values of 6.05+/-0.13 (vas deferens) and 6.98+/-0.07 (ileum) were derived. In both preparations, SB9 behaved as a slow onset, slow offset antagonist. Incubation of three oocytes in the presence of ATP produced an increase in inorganic phosphate (P(i)) over a 30-min period, which amounted to 35.1+/-1.9 microM P(i) from 100 microM ATP. SB9 (10-1000 microM) reduced this degradation (pIC(50)=4.33+/-0.10). The results illustrate that SB9 is a high-affinity P2Y(1) receptor antagonist with a remarkable selectivity for P2Y(1) vs. P2X(1) receptors (about 10-fold) and ecto-nucleotidases (447-fold). These properties make it unique among the pyridoxal-5'-phosphate and suramin derivatives reported to date.

  14. Effect of purine receptor P2X7 in pericyte of retinal microvascular apoptosis%嘌呤受体P2X7对视网膜毛细血管周细胞凋亡的影响

    Institute of Scientific and Technical Information of China (English)

    左炜; 祝芸芸; 于洪涛; 利焕廉; 周金文; 王恒

    2014-01-01

    AIM: To discuss the functional significance of purine receptor P2X7 in retinal capillary pericytes rats. METHODS:The TUNEL test was applied to observe the survival rate of normal retinal capillary pericytes and diabetic retinal capillary pericytes which were affected by P2X7 agonist BzATP and antagonist OxATP in microscopy. RESULTS: Activation of P2X7 receptors caused occurence of apoptosis in retinal capillary pericytes. Compared with normal retinal capillary pericytes, when they were at the same concentration or time, the diabetic retinal capillary pericytes caused much more apoptosis than normal retinal capillary pericytes. The antagonist OxATP could significantly reduce the toxic effects activated by BzATP, and then increased the livability of retinal capillary pericytes. CONCLUSION:The activity of P2X7 receptor plays a regulatory role on RPC apoptosis.%目的:探讨嘌呤受体P2X7在体外培养大鼠视网膜毛细血管周细胞上的功能意义。  方法:利用显微镜下观察结合TUNEL 计数法分别测定P2 X7激动剂BzATP和拮抗剂OxATP对体外培养的正常视网膜毛细血管周细胞以及糖尿病大鼠视网膜毛细血管周细胞存活率的影响。  结果:P2 X 7受体激动后可介导视网膜毛细血管周细胞死亡,糖尿病大鼠视网膜毛细血管周细胞较正常视网膜毛细血管周细胞,在同等激动剂浓度下或在同样的时间点,能引起更多的细胞凋亡。而拮抗剂OxATP 可以明显减轻BzATP对视网膜毛细血管周细胞的毒性作用,提高其存活率。  结论:P2 X 7受体活性对视网膜毛细血管周细胞凋亡有一定调控作用。

  15. Genomic saturation mutagenesis and polygenic analysis identify novel yeast genes affecting ethyl acetate production, a non-selectable polygenic trait

    Directory of Open Access Journals (Sweden)

    Tom Den Abt

    2016-03-01

    Full Text Available Isolation of mutants in populations of microorganisms has been a valuable tool in experimental genetics for decades. The main disadvantage, however, is the inability of isolating mutants in non-selectable polygenic traits. Most traits of organisms, however, are non-selectable and polygenic, including industrially important properties of microorganisms. The advent of powerful technologies for polygenic analysis of complex traits has allowed simultaneous identification of multiple causative mutations among many thousands of irrelevant mutations. We now show that this also applies to haploid strains of which the genome has been loaded with induced mutations so as to affect as many non-selectable, polygenic traits as possible. We have introduced about 900 mutations into single haploid yeast strains using multiple rounds of EMS mutagenesis, while maintaining the mating capacity required for genetic mapping. We screened the strains for defects in flavor production, an important non-selectable, polygenic trait in yeast alcoholic beverage production. A haploid strain with multiple induced mutations showing reduced ethyl acetate production in semi-anaerobic fermentation, was selected and the underlying quantitative trait loci (QTLs were mapped using pooled-segregant whole-genome sequence analysis after crossing with an unrelated haploid strain. Reciprocal hemizygosity analysis and allele exchange identified PMA1 and CEM1 as causative mutant alleles and TPS1 as a causative genetic background allele. The case of CEM1 revealed that relevant mutations without observable effect in the haploid strain with multiple induced mutations (in this case due to defective mitochondria can be identified by polygenic analysis as long as the mutations have an effect in part of the segregants (in this case those that regained fully functional mitochondria. Our results show that genomic saturation mutagenesis combined with complex trait polygenic analysis could be used

  16. P2P Overlay Network Clustering Service%P2P覆盖网聚类服务

    Institute of Scientific and Technical Information of China (English)

    程实; 吴产乐; 程伟; 乐俊; 贺莲

    2010-01-01

    为了提供有效的拓扑感知服务,论述了对等(P2P)传输损耗现象和节点距离的度量空间性质,提出了P2P覆盖网聚类服务方案.该方案通过聚类初始化、优化接口和算法实现对P2P用户节点进行管理,维护聚类视图(CV),通过CV查询接口和CV映射算法提供跨P2P应用的拓扑感知支持.模拟实验数据表明,该方案比现有的基于坐标空间映射的方法,能提供更精确的最近邻居推荐结果.

  17. Extracellular ATP mediates necrotic cell swelling in SN4741 dopaminergic neurons through P2X7 receptors.

    Science.gov (United States)

    Jun, Dong-Jae; Kim, Jaeyoon; Jung, Sang-Yong; Song, Ran; Noh, Ji-Hyun; Park, Yong-Soo; Ryu, Sung-Ho; Kim, Joung-Hun; Kong, Young-Yun; Chung, Jun-Mo; Kim, Kyong-Tai

    2007-12-28

    Extracellular ATP has recently been identified as an important regulator of cell death in response to pathological insults. When SN4741 cells, which are dopaminergic neurons derived from the substantia nigra of transgenic mouse embryos, are exposed to ATP, cell death occurs. This cell death is associated with prominent cell swelling, loss of ER integrity, the formation of many large cytoplasmic vacuoles, and subsequent cytolysis and DNA release. In addition, the cleavage of caspase-3, a hallmark of apoptosis, is induced by ATP treatment. However, caspase inhibitors do not overcome ATP-induced cell death, indicating that both necrosis and apoptosis are associated with ATP-induced cell death and suggesting that a necrotic event might override the apoptotic process. In this study we also found that P2X(7) receptors (P2X(7)Rs) are abundantly expressed in SN4741 cells, and both ATP-induced swelling and cell death are reversed by pretreatment with the P2X(7)Rs antagonist, KN62, or by knock-down of P2X(7)Rs with small interfering RNAs. Therefore, extracellular ATP release from injured tissues may act as an accelerating factor in necrotic SN4741 dopaminergic cell death via P2X(7)Rs.

  18. Inflammasome activation in bovine monocytes by extracellular ATP does not require the purinergic receptor P2X7.

    Science.gov (United States)

    Hussen, Jamal; Düvel, Anna; Koy, Mirja; Schuberth, Hans-Joachim

    2012-10-01

    Extracellular adenosine triphosphate (ATP) is a second signal for the assembly of the NLR family, pyrin domain-containing 3 (NLRP3) inflammasome, which form a framework to activate caspase 1, leading to the processing and secretion of the pro-inflammatory cytokine interleukin-1β (IL-1β). The aim of the present study was to investigate the role of the ATP-gated ion channel subtype P2X7 receptor in the inflammasome activation of bovine monocytes. ATP-induced inflammasome assembly in bovine monocytes was shown by caspase-1 activation and the release of IL-1β by LPS/ATP-stimulated bovine cells. The IL-1β release depended on potassium efflux but was independent of reactive oxygen generation of bovine monocytes. Unlike in the human system, a P2X7 receptor antagonist did not block the ATP-induced release of IL-1β of LPS-primed bovine cells. P2X7 mediated pore formation was observed in subsets of bovine T lymphocytes (CD4+>CD8+) but not in monocytes. In addition, ATP and 2-MeSATP but not the high affinity P2X7 agonist BzATP induced calcium influx in bovine monocytes. The data indicate that ROS generation plays no role in the ATP-induced activation of inflammasome in bovine monocytes and that P2X7-mediated pore formation is not necessary for the release of Interleukin-1β.

  19. Determinants of Default in P2P Lending.

    Science.gov (United States)

    Serrano-Cinca, Carlos; Gutiérrez-Nieto, Begoña; López-Palacios, Luz

    2015-01-01

    This paper studies P2P lending and the factors explaining loan default. This is an important issue because in P2P lending individual investors bear the credit risk, instead of financial institutions, which are experts in dealing with this risk. P2P lenders suffer a severe problem of information asymmetry, because they are at a disadvantage facing the borrower. For this reason, P2P lending sites provide potential lenders with information about borrowers and their loan purpose. They also assign a grade to each loan. The empirical study is based on loans' data collected from Lending Club (N = 24,449) from 2008 to 2014 that are first analyzed by using univariate means tests and survival analysis. Factors explaining default are loan purpose, annual income, current housing situation, credit history and indebtedness. Secondly, a logistic regression model is developed to predict defaults. The grade assigned by the P2P lending site is the most predictive factor of default, but the accuracy of the model is improved by adding other information, especially the borrower's debt level.

  20. Determinants of Default in P2P Lending.

    Directory of Open Access Journals (Sweden)

    Carlos Serrano-Cinca

    Full Text Available This paper studies P2P lending and the factors explaining loan default. This is an important issue because in P2P lending individual investors bear the credit risk, instead of financial institutions, which are experts in dealing with this risk. P2P lenders suffer a severe problem of information asymmetry, because they are at a disadvantage facing the borrower. For this reason, P2P lending sites provide potential lenders with information about borrowers and their loan purpose. They also assign a grade to each loan. The empirical study is based on loans' data collected from Lending Club (N = 24,449 from 2008 to 2014 that are first analyzed by using univariate means tests and survival analysis. Factors explaining default are loan purpose, annual income, current housing situation, credit history and indebtedness. Secondly, a logistic regression model is developed to predict defaults. The grade assigned by the P2P lending site is the most predictive factor of default, but the accuracy of the model is improved by adding other information, especially the borrower's debt level.

  1. Synaptosomal protein synthesis in P2 and Ficoll purified fractions.

    Science.gov (United States)

    Eyman, Maria; Cefaliello, Carolina; Bruno, Anna Paola; Bruno, Annapaola; Crispino, Marianna; Giuditta, Antonio

    2012-01-30

    Cytoplasmic protein synthesis of brain synaptosomes has generally been determined in the Ficoll purified fraction which contains fewer contaminating mitochondria, microsomes and myelin fragments than the parent P2 fraction. Using a highly selective assay of this activity we have compared the total translation activity and the specific activity of the proteins synthesized by either fraction in control rats and in rats trained for a two-way active avoidance task. In control rats the specific activity remained essentially the same in both fractions but in trained rats the value of the Ficoll fraction was markedly lower (38.5%) than in the P2 fraction. Furthermore, the total translation activity of the Ficoll fraction was 30% lower than in the P2 fraction in control rats and 62% lower in trained rats. These decrements indicate that a large proportion of active synaptosomes present in the P2 fraction is not recovered in the Ficoll fraction, notably in rats undergoing plastic brain changes. We conclude that cytoplasmic protein synthesis of brain synaptosomes is better preserved in the P2 fraction.

  2. Determinants of Default in P2P Lending

    Science.gov (United States)

    2015-01-01

    This paper studies P2P lending and the factors explaining loan default. This is an important issue because in P2P lending individual investors bear the credit risk, instead of financial institutions, which are experts in dealing with this risk. P2P lenders suffer a severe problem of information asymmetry, because they are at a disadvantage facing the borrower. For this reason, P2P lending sites provide potential lenders with information about borrowers and their loan purpose. They also assign a grade to each loan. The empirical study is based on loans’ data collected from Lending Club (N = 24,449) from 2008 to 2014 that are first analyzed by using univariate means tests and survival analysis. Factors explaining default are loan purpose, annual income, current housing situation, credit history and indebtedness. Secondly, a logistic regression model is developed to predict defaults. The grade assigned by the P2P lending site is the most predictive factor of default, but the accuracy of the model is improved by adding other information, especially the borrower’s debt level. PMID:26425854

  3. Managing Linguistic Data Summaries in Advanced P2P Applications

    Science.gov (United States)

    Hayek, Rabab; Raschia, Guillaume; Valduriez, Patrick; Mouaddib, Noureddine

    As the amount of stored data increases, data localization techniques become no longer sufficient in P2P systems. A practical approach is to rely on compact database summaries rather than raw database records, whose access is costly in large P2P systems. In this chapter, we describe a solution for managing linguistic data summaries in advanced P2P applications which are dealing with semantically rich data. The produced summaries are synthetic, multidimensional views over relational tables. The novelty of this proposal relies on the double summary exploitation in distributed P2P systems. First, as semantic indexes, they support locating relevant nodes based on their data descriptions. Second, due to their intelligibility, these summaries can be directly queried and thus approximately answer a query without the need for exploring original data. The proposed solution consists first in defining a summary model for hierarchical P2P systems. Second, appropriate algorithms for summary creation and maintenance are presented. A query processing mechanism, which relies on summary querying, is then proposed to demonstrate the benefits that might be obtained from summary exploitation.

  4. Behavioural Correlation for Detecting P2P Bots

    CERN Document Server

    Al-Hammadi, Yousof

    2010-01-01

    In the past few years, IRC bots, malicious programs which are remotely controlled by the attacker through IRC servers, have become a major threat to the Internet and users. These bots can be used in different malicious ways such as issuing distributed denial of services attacks to shutdown other networks and services, keystrokes logging, spamming, traffic sniffing cause serious disruption on networks and users. New bots use peer to peer (P2P) protocols start to appear as the upcoming threat to Internet security due to the fact that P2P bots do not have a centralized point to shutdown or traceback, thus making the detection of P2P bots is a real challenge. In response to these threats, we present an algorithm to detect an individual P2P bot running on a system by correlating its activities. Our evaluation shows that correlating different activities generated by P2P bots within a specified time period can detect these kind of bots.

  5. Effects of antidepressants on P2X7 receptors.

    Science.gov (United States)

    Wang, Wei; Xiang, Zheng-Hua; Jiang, Chun-Lei; Liu, Wei-Zhi; Shang, Zhi-Lei

    2016-08-30

    Antidepressants including paroxetine, fluoxetine and desipramine are commonly used for treating depression. P2×7 receptors are member of the P2X family. Recent studies indicate that these receptors may constitute a novel potential target for the treatment of depression. In the present study, we examined the action of these antidepressants on cloned rat P2×7 receptors that were stably expressed in human embryonic kidney (HEK) 293 cells by using the whole-cell patch-clamp technique, and found that paroxetine at a dose of 10µM could significantly reduce the inward currents evoked by the P2×7 receptors agonist BzATP by pre-incubation for 6-12 but not by acute application (10µM) or pre-incubation for 2-6h at a dose of 1µM, 3µM or 10µM paroxetine. Neither fluoxetine nor desipramine had significant effects on currents evoked by BzATP either applied acutely or by pre-incubation at various concentrations. These results suggest that the sensitivity of rat P2×7 receptors to antidepressants is different, which may represent an unknown mechanism by which these drugs exert their therapeutic effects and side effects.

  6. A Framework For Concept Drifting P2P Traffic Identification

    Directory of Open Access Journals (Sweden)

    Guanghui Yan

    2013-08-01

    Full Text Available Identification of network traffic using port-based or payload-based analysis is becoming increasing difficult with many Peer-to-Peer (P2P application using dynamic ports, masquerading techniques, and encryption to avoid detection. To overcome this problem, several machine learning technique were proposed to classify P2P traffics. But in the real P2P network environment, new communities of peers often attend and old communities of peers often leave. It requires the identification methods to be capable of coping with concept drift, and updating the model incrementally. In this paper, we present a concept-adapting algorithm CluMC which is based on streaming data mining techniques to identify P2P applications in Internet traffic. The CluMC use micro-cluster structures which contain potential micro-cluster structures and outlier micro-cluster structures to classify the P2P traffic and discover the concept drift with limited memory. Our performance study over a number of real data sets that we captured at a main gateway router demonstrates the effectiveness and efficiency of our method.

  7. P2X7 Receptors as a Transducer in the Co-Occurrence of Neurological/Psychiatric and Cardiovascular Disorders: A Hypothesis

    Directory of Open Access Journals (Sweden)

    Stephen D. Skaper

    2009-01-01

    Full Text Available Background. Over-stimulation of the purinergic P2X7 receptor may bring about cellular dysfunction and injury in settings of neurodegeneration, chronic inflammation, as well as in psychiatric and cardiovascular diseases. Here we speculate how P2X7 receptor over-activation may lead to the co-occurrence of neurological and psychiatric disorders with cardiovascular disorders. Presentation. We hypothesize that proinflammatory cytokines, in particular interleukin-1, are key players in the pathophysiology of neurological, psychiatric, and cardiovascular diseases. Critically, this premise is based on a role for the P2X7 receptor in triggering a rise in these cytokines. Given the broad distribution of P2X7 receptors in nervous, immune, and vascular tissue cells, this receptor is proposed as central in linking the nervous, immune, and cardiovascular systems. Testing. Investigate, retrospectively, whether a bidirectional link can be established between illnesses with a proinflammatory component (e.g., inflammatory and chronic neuropathic pain and cardiovascular disease, for example, hypertension, and whether patients treated with anti-inflammatory drugs have a lower incidence of disease complications. Positive outcome would indicate a prospective study to evaluate therapeutic efficacy of P2X7 receptor antagonists. Implications. It should be stressed that sufficient direct evidence does not exist at present supporting our hypothesis. However, a positive outcome would encourage the further development of P2X7 receptor antagonists and their application to limit the co-occurrence of neurological, psychiatric, and cardiovascular disorders.

  8. P2P在线视频研究综述%Survey on P2P video streaming systems

    Institute of Scientific and Technical Information of China (English)

    李真真; 张志斌; 杜跃进

    2009-01-01

    P2P技术凭借其开放性、可扩展性和高性价比等优点成为了目前解决在线视频问题的有效手段之一.虽然P2P技术在文件共享和IP语音等方面的应用已经基本趋于成熟,但其在在线视频领域的应用尚处于起步阶段,还面临着许多需要解决的问题.对P2P在线视频进行了全面而深入的分析,首先介绍了网络广播分类及体系结构设计,整理和总结了已有的关于P2P在线视频系统的测量研究结果,最后对于P2P在线视频信任和污染攻击等安全问题进行了概述.%P2P technology has become one of the most effective approaches to internet video broadcast for its simple deployment, good scalability and high cost-effectiveness ratio. P2P applications such as file download and voice over IP have gained tremendous popularity, while video broadcast is still in its early stage and there are a number of key technical challenges that need to be overcome. This paper provided a comprehensive and in-depth analysis of the P2P video streaming, and discussed the characteristics of video broadcast applications and reviewed the approaches to video streaming systems architecture design. After surveying the results of measurement studied on P2P video streaming systems, then the paper overviewed security aspects of P2P live video streaming systems such as pollution attack and DoS attack.

  9. Synthesis of potential mescaline antagonists.

    Science.gov (United States)

    DeSantis, F; Nieforth, K A

    1976-10-01

    1-[2-(3,4,5-Trimethoxyphenyl)ethyl]-3-pyrroline, 2-(3,4,5-trimethoxybenzyl)-1,2,3,6-tetrahydropyridine, N-n-propylmescaline, N-cyclopropylmethylmescaline, and N-allylmescaline were synthesized as potential mescaline antagonists. The ability of these compounds to antagonize mescaline-induced disruption of swim behavior is also given.

  10. Excitatory amino acid receptor antagonists

    DEFF Research Database (Denmark)

    Johansen, T N; Frydenvang, Karla Andrea; Ebert, B

    1997-01-01

    We have previously shown that (RS)-2-amino-2-(5-tert-butyl-3-hydroxyisoxazol-4-yl)acetic acid (ATAA) is an antagonist at N-methyl-D-aspartic acid (NMDA) and (RS)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA) receptors. We have now resolved ATAA via diastereomeric salt formation......)-phenylethylamine salt of N-BOC-(R)-ATAA. Like ATAA, neither (R)- nor (S)-ATAA significantly affected (IC50 > 100 microM) the receptor binding of tritiated AMPA, kainic acid, or (RS)-3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid, the latter being a competitive NMDA antagonist. Electrophysiological experiments......, using the rat cortical wedge preparation, showed the NMDA antagonist effect as well as the AMPA antagonist effect of ATAA to reside exclusively in the (R)-enantiomer (Ki = 75 +/- 5 microM and 57 +/- 1 microM, respectively). Neither (R)- nor (S)-ATAA significantly reduced kainic acid-induced excitation...

  11. DEVELOPMENT OF NEW LHRH ANTAGONISTS

    Institute of Scientific and Technical Information of China (English)

    PENGDun-Ren; XIAOShao-Bo

    1989-01-01

    An ideal antagonist of LHRH is one which can act on the pitutary to inhibit LHRH-stimulatod LH / FSH secretion by competitive occupying the LHRH receptor in the pitutary gland. Its action should be very specific, fast and highly effective, the durations

  12. Market Design for a P2P Backup System

    Science.gov (United States)

    Seuken, Sven; Charles, Denis; Chickering, Max; Puri, Sidd

    Peer-to-peer (P2P) backup systems are an attractive alternative to server-based systems because the immense costs of large data centers can be saved by using idle resources on millions of private computers instead. This paper presents the design and theoretical analysis of a market for a P2P backup system. While our long-term goal is an open resource exchange market using real money, here we consider a system where monetary transfers are prohibited. A user who wants to backup his data must in return supply some of his resources (storage space, upload and download bandwidth) to the system.We propose a hybrid P2P architecture where all backup data is transferred directly between peers, but a dedicated server coordinates all operations and maintains meta-data. We achieve high reliability guarantees while keeping our data replication factor low by adopting sophisticated erasure coding technology (cf., [2]).

  13. P2 receptor-mediated signaling in mast cell biology.

    Science.gov (United States)

    Bulanova, Elena; Bulfone-Paus, Silvia

    2010-03-01

    Mast cells are widely recognized as effector cells of allergic inflammatory reactions. They contribute to the pathogenesis of different chronic inflammatory diseases, wound healing, fibrosis, thrombosis/fibrinolysis, and anti-tumor immune responses. In this paper, we summarized the role of P2X and P2Y receptors in mast cell activation and effector functions. Mast cells are an abundant source of ATP which is stored in their granules and secreted upon activation. We discuss the contribution of mast cells to the extracellular ATP release and to the maintenance of extracellular nucleotides pool. Recent publications highlight the importance of purinergic signaling for the pathogenesis of chronic airway inflammation. Therefore, the role of ATP and P2 receptors in allergic inflammation with focus on mast cells was analyzed. Finally, ATP functions as mast cell autocrine/paracrine factor and as messenger in intercellular communication between mast cells, nerves, and glia in the central nervous system.

  14. P2迈入高清时代

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    今年NAB上,松下电器展出了以P2和高清为核心的最新产品,以工作流程为主线展示了P2和高清通过USB、IEEE1394连接全流程的工作模式。在新闻采集和节目制作市场,着重树立DVCPRO及DVCPRO50为图像采集的标准。占松下展台面积近一半的HD3D影院,以高清立体电影的方式,展示了松下电器参展的主题——P2高清和相关产品的发展方向。

  15. PROSE: Proactive, Selective CDN Participation for P2P Streaming

    Institute of Scientific and Technical Information of China (English)

    Zhi-Hui Lv; Li-Jiang Chen; Jie Wu; Da Deng; Si-Jia Huang; Yi Huang

    2013-01-01

    Many production peer-to-peer (P2P) streaming systems use content delivery networks (CDN) to protect the user's quality of experiences.Thus,how to efficiently utilize the capacity of CDN (e.g.,which peers receive services from the CDN nodes) is a problem of practical significance.Existing solutions adopt a passive,on-demand approach,which is inefficient iu utilizing CDN resources.In this paper,we propose PROSE,a simple,novel scheme to achieve proactive,selective CDN participation for P2P streaming.PROSE introduces novel concepts such as choke point expansion nodes/super nodes and leads to efficient,light-weighted,and distributed algorithms to identify and serve these nodes using CDN.Our experimental results show that PROSE achieves at least 10%~25% performance improvement and 2~4 times overhead reduction compared with existing general CDN-P2P-hybrid schemes.

  16. 松下:P2迈入HD时代

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    今年NAB上.松下电器展出了以P2和HD为核心的最新产品.以工作流程为主线展示了P2和HD通过USB、IEEE1394连接全流程的工作模式。在新闻采集和节目制作市场.着重树立DVCPRO以及DVCPRO 50为图像采集的标准。占展台面积近一半的HD 3D影院.以高清立体电影的方式,展示了松下电器参展的主题-P2 HD和相关产品的发展方向。

  17. Model of Controlling the Hubs in P2P Networks

    Directory of Open Access Journals (Sweden)

    Yuhua Liu

    2009-06-01

    Full Text Available Research into the hubs in Peer-to-Peer (P2P networks, and present a new method to avoid generating the hubs in the networks by controlling the logical topology structure of P2P networks. We firstly introduce the controlling ideas about hierarchizing the hubs. Then, we disclose and interpret the controlling model, and give out the concrete method to carry it out. Finally, we validate our controlling model via simulations and the simulation results demonstrate that our work is effective to control the hubs in P2P networks. Thus, this model can improve the network competence to defend against coordinated attacks, promote the network robustness, and ensure the network would develop continually and healthily.

  18. On Using Seeders for P2P Live Streaming

    CERN Document Server

    Mathieu, Fabien

    2011-01-01

    Seeders (peers that do not request anything but contribute to the system) are a powerful concept in peer-to-peer (P2P). They allow to leverage the capacities of a P2P system. While seeding is a natural idea for filesharing or video-on-demand applications, it seems somehow counter-intuitive in the context of live streaming. This paper aims at describing the feasibility and performance of P2P live seeding. After a formal definition of "live seeding" and efficiency, we consider the theoretical performance of systems where the overhead is neglected. We then propose a linear overhead model and extend the results for this model, for a single seeder and for a set of seeders as well (it is not always possible to perfectly aggregate individual efficiencies in a given system).

  19. Compromising Tor Anonymity Exploiting P2P Information Leakage

    CERN Document Server

    Manils, Pere; Blond, Stevens Le; Kaafar, Mohamed Ali; Castelluccia, Claude; Legout, Arnaud; Dabbous, Walid

    2010-01-01

    Privacy of users in P2P networks goes far beyond their current usage and is a fundamental requirement to the adoption of P2P protocols for legal usage. In a climate of cold war between these users and anti-piracy groups, more and more users are moving to anonymizing networks in an attempt to hide their identity. However, when not designed to protect users information, a P2P protocol would leak information that may compromise the identity of its users. In this paper, we first present three attacks targeting BitTorrent users on top of Tor that reveal their real IP addresses. In a second step, we analyze the Tor usage by BitTorrent users and compare it to its usage outside of Tor. Finally, we depict the risks induced by this de-anonymization and show that users' privacy violation goes beyond BitTorrent traffic and contaminates other protocols such as HTTP.

  20. Extracellular ATP and P2X7 receptors in neurodegeneration.

    Science.gov (United States)

    Le Feuvre, Rosalind; Brough, David; Rothwell, Nancy

    2002-07-05

    Neuronal injury and cell death in the central nervous system (CNS) are underlying features of neurodegenerative disorders. However, our understanding of the fundamental mechanisms involved is still limited. Inflammatory processes mediated by cytokines, and interleukin-1 (IL-1) in particular, play a significant role in neuronal death following pathological insults. Despite this growing area of research, very little is known about the factors regulating the expression, cleavage and release of interleukin-1 in the brain. Recent studies on immune cells demonstrate that extracellular ATP can act as a potent stimulus for the maturation and release of interleukin-1beta, via activation of P2X7 receptors. Stimulation of P2X7 receptors with ATP has dramatic cytotoxic properties and a wider role in neurodegenerative processes is possible. This review discusses the potential involvement of extracellular ATP and P2X7 receptors as regulators of interleukin-1-mediated neuropathologies and thus as a mediator of cell death following pathological insults.

  1. Calcium signaling and the novel anti-proliferative effect of the UTP-sensitive P2Y11 receptor in rat cardiac myofibroblasts.

    Science.gov (United States)

    Certal, Mariana; Vinhas, Adriana; Pinheiro, Ana Rita; Ferreirinha, Fátima; Barros-Barbosa, Aurora Raquel; Silva, Isabel; Costa, Maria Adelina; Correia-de-Sá, Paulo

    2015-11-01

    During myocardial ischemia and reperfusion both purines and pyrimidines are released into the extracellular milieu, thus creating a signaling wave that propagates to neighboring cells via membrane-bound P2 purinoceptors activation. Cardiac fibroblasts (CF) are important players in heart remodeling, electrophysiological changes and hemodynamic alterations following myocardial infarction. Here, we investigated the role UTP on calcium signaling and proliferation of CF cultured from ventricles of adult rats. Co-expression of discoidin domain receptor 2 and α-smooth muscle actin indicate that cultured CF are activated myofibroblasts. Intracellular calcium ([Ca(2+)]i) signals were monitored in cells loaded with Fluo-4 NW. CF proliferation was evaluated by the MTT assay. UTP and the selective P2Y4 agonist, MRS4062, caused a fast desensitizing [Ca(2+)]i rise originated from thapsigargin-sensitive internal stores, which partially declined to a plateau providing the existence of Ca(2+) in the extracellular fluid. The biphasic [Ca(2+)]i response to UTP was attenuated respectively by P2Y4 blockers, like reactive blue-2 and suramin, and by the P2Y11 antagonist, NF340. UTP and the P2Y2 receptor agonist MRS2768 increased, whereas the selective P2Y11 agonist NF546 decreased, CF growth; MRS4062 was ineffective. Blockage of the P2Y11 receptor or its coupling to adenylate cyclase boosted UTP-induced CF proliferation. Confocal microscopy and Western blot analysis confirmed the presence of P2Y2, P2Y4 and P2Y11 receptors. Data indicate that besides P2Y4 and P2Y2 receptors which are responsible for UTP-induced [Ca(2+)]i transients and growth of CF, respectively, synchronous activation of the previously unrecognized P2Y11 receptor may represent an important target for anti-fibrotic intervention in cardiac remodeling.

  2. Nanomolar ambient ATP decelerates P2X3 receptor kinetics.

    Science.gov (United States)

    Grote, Alexander; Hans, Michael; Boldogkoi, Zsolt; Zimmer, Andreas; Steinhäuser, Christian; Jabs, Ronald

    2008-12-01

    Homomeric P2X receptors differ in their electrophysiological and pharmacological profiles. The rapidly activating and desensitizing P2X3 receptors are known for their involvement in pain signalling pathways. Modulatory effects on P2X3 receptors have been reported for low concentrations of ATP ([ATP]). This includes both, enhancement and reduction of receptor currents. The first has been reported to be mediated by activation of ectoprotein kinases and high affinity desensitization (HAD), respectively. Both processes influence receptor current amplitudes. Here we describe a new phenomenon, the modulatory influence of ambient low [ATP] on P2X3 receptor kinetics. First, we studied in HEK cells whether persistent ATP affects current decay. To this end, P2X3 receptor mediated currents, elicited by pressure application of saturating [ATP], were analyzed after pre-application of low [ATP]. Second, UV-flash photolysis of ATP was employed to investigate whether submicromolar [ATP] affects receptor activation. Finally we confirmed the action of nanomolar [ATP] on native P2X3 receptors of neurons freshly isolated from rat dorsal root ganglia. We found that persistent low [ATP] caused pronounced deceleration of receptor current activation and decay. This priming effect indicates a mechanism different from HAD. It could be explained by a pre-opening receptor isomerization, induced by the occupation of a high affinity binding site already at the resting state. The observed modulation of the receptor kinetics could be considered as a physiological fine tuning mechanism of the nociceptive system, driven by the actual ambient agonist concentration.

  3. Mobile P2P Web Services Using SIP

    Directory of Open Access Journals (Sweden)

    Guido Gehlen

    2007-01-01

    Full Text Available Telecommunication networks and the Internet are growing together. Peer-to-Peer (P2P services which are originally offered by network providers, like telephony and messaging, are provided through VoIP and Instant Messaging (IM by Internet service providers, too. The IP Multimedia Subsystem (IMS is the answer of the telecommunication industry to this trend and aims at providing Internet P2P and multimedia services controlled by the network operators. The IMS provides mobility and session management as well as message routing, security, and billing.

  4. P2X7 receptor and caspase 1 activation are central to airway inflammation observed after exposure to tobacco smoke.

    Directory of Open Access Journals (Sweden)

    Suffwan Eltom

    Full Text Available Chronic Obstructive Pulmonary Disease (COPD is a cigarette smoke (CS-driven inflammatory airway disease with an increasing global prevalence. Currently there is no effective medication to stop the relentless progression of this disease. It has recently been shown that an activator of the P2X7/inflammasome pathway, ATP, and the resultant products (IL-1β/IL-18 are increased in COPD patients. The aim of this study was to determine whether activation of the P2X7/caspase 1 pathway has a functional role in CS-induced airway inflammation. Mice were exposed to CS twice a day to induce COPD-like inflammation and the role of the P2X7 receptor was investigated. We have demonstrated that CS-induced neutrophilia in a pre-clinical model is temporally associated with markers of inflammasome activation, (increased caspase 1 activity and release of IL-1β/IL-18 in the lungs. A selective P2X7 receptor antagonist and mice genetically modified so that the P2X7 receptors were non-functional attenuated caspase 1 activation, IL-1β release and airway neutrophilia. Furthermore, we demonstrated that the role of this pathway was not restricted to early stages of disease development by showing increased caspase 1 activation in lungs from a more chronic exposure to CS and from patients with COPD. This translational data suggests the P2X7/Inflammasome pathway plays an ongoing role in disease pathogenesis. These results advocate the critical role of the P2X7/caspase 1 axis in CS-induced inflammation, highlighting this as a possible therapeutic target in combating COPD.

  5. Survey on P2P Network Pollutions%P2P网络数据污染综述

    Institute of Scientific and Technical Information of China (English)

    王勇; 云晓春; 秦志光; 郭莉; 程红蓉

    2011-01-01

    In recent years,the security issues of Peer-to-Peer networking applications(P2P) are becoming the hot spots of network security research.The pollution and poisoning problems of shared content in P2P network present a new challenge for P2P networking security:such as how to find and locate the polluted data,how to modeling the pollution and poisoning process, and how to prevent the spreads of polluted contents efficiently etc.In this paper, the up-to-date researching results were discussed in detail from the three main angles as the polluted data measurements, the modeling processes, and the pollution constrain strategies; some key issues related to P2P network pollutions were analyzed.Finally, the paper pointed out the future possible researching trends on P2P network pollutions.%对等网络应用(Peer-to-Peer networking applications,P2P)相关的安全威胁已经成为广受关注的网络安全课题.P2P网络共享文件内容的数据污染给P2P网络安全带来新的难题:例如,如何快速定位发现污染数据,分析污染数据特征模型,寻求高效低代价的数据污染治理策略等还有待进一步深入分析研究.针对P2P网络数据污染,从污染数据监测、数据污染特征模型分析以及数据污染治理策略等三方面,阐述了当前该邻域的主要研究动态,分析了数据污染相关研究的关键问题,最后指明了该邻域未来可能的发展方向.

  6. ADP stimulates human endothelial cell migration via P2Y1 nucleotide receptor-mediated mitogen-activated protein kinase pathways.

    Science.gov (United States)

    Shen, Jianzhong; DiCorleto, Paul E

    2008-02-29

    Extensive research on the role of ADP in platelet activation led to the design of new anti-thrombotic drugs, such as clopidogrel (Plavix; sanofi-aventis); however, very little is known about the ADP-preferring nucleotide receptors (P2Y1, P2Y12, and P2Y13) in endothelium. Here, we show that ADP stimulates migration of cultured human umbilical vein endothelial cells (HUVECs) in both Boyden chamber and in vitro wound repair assays. This promigratory effect was mimicked by 2-MeSADP, but not by AMP, and was inhibited by MRS2179 (P2Y1 receptor antagonist) but not by AR-C69931MX (P2Y12/13 receptor antagonist). RT-PCR revealed abundant P2Y1, barely detectable P2Y12, and absent P2Y13 receptor message in these cells. In addition, both ADP and 2-MeSADP, but not AMP, activated the mitogen-activated protein kinase pathways as evidenced by increased phosphorylation of extracellular signal-regulated kinase (ERK)1/2, c-Jun N-terminal kinase (JNK), and p38 kinase. ADP also stimulated phosphorylation of p90RSK, a downstream substrate of phosphorylated ERK1/2, and induced phosphorylation of such transcription factors downstream of the JNK and p38 pathways as c-Jun and activating transcription factor-2. These signaling events were inhibited by MRS2179 but not by AR-C69931MX. Furthermore, blockade of the ERK or JNK pathways by U0126 and SP600125, respectively, abolished ADP- and 2-MeSADP-stimulated HUVEC migration. However, inhibition of the p38 pathway by SB203580 partially suppressed ADP- and 2-MeSADP-induced HUVEC migration. We conclude that ADP promotes human endothelial cell migration by activating P2Y1 receptor-mediated MAPK pathways, possibly contributing to reendothelialization and angiogenesis after vascular injury.

  7. Involvement of P2X7 receptor signaling on regulating the differentiation of Th17 cells and type II collagen-induced arthritis in mice

    Science.gov (United States)

    Fan, Zhi-Dan; Zhang, Ya-Yuan; Guo, Yi-Hong; Huang, Na; Ma, Hui-Hui; Huang, Hui; Yu, Hai-Guo

    2016-01-01

    Interleukin (IL)-17 producing T helper (Th17) cells are major effector cells in the pathogenesis of rheumatoid arthritis (RA). The P2X7 receptor (P2X7R) has emerged as a potential site in the regulation of inflammation in RA but little is known of its functional role on the differentiation of Th17 cells. This study investigates the in vitro and in vivo effects of P2X7R on Th17 cell differentiation during type II collagen (CII) induced experimental arthritis model. In CII-treated dendritic cells (DCs) and DC/CD4+ T coculture system, pretreatment with pharmacological antagonists of P2X7R (Suramin and A-438079) caused strong inhibition of production of Th17-promoting cytokines (IL-1β, TGF-β1, IL-23p19 and IL-6). Exposure to CII induced the elevation of mRNAs encoding retinoic acid receptor-related orphan receptor α and γt, which were abolished by pretreatment with P2X7R antagonists. Furthermore, blocking P2X7R signaling abolished the CII-mediated increase in IL-17A. Blockade of P2X7R remarkably inhibited hind paw swelling and ameliorated pathological changes in ankle joint of the collagen-induced arthritis mice. Thus, we demonstrated a novel function for P2X7R signaling in regulating CII-induced differentiation of Th17 cells. P2X7R signaling facilitates the development of the sophisticated network of DC-derived cytokines that favors a Th17 phenotype. PMID:27775097

  8. Involvement of microglial P2X7 receptors and downstream signaling pathways in long-term potentiation of spinal nociceptive responses.

    Science.gov (United States)

    Chu, Yu-Xia; Zhang, Yan; Zhang, Yu-Qiu; Zhao, Zhi-Qi

    2010-10-01

    Tetanic stimulation of the sciatic nerve (TSS) produces long-term potentiation (LTP) of C-fiber-evoked field potentials in the spinal cord. This potentiation is considered to be a substrate for long-lasting sensitization in the spinal pain pathway. Because microglia have previously been shown to regulate the induction of spinal LTP, we hypothesize that P2X7 receptors (P2X7R), which are predominantly expressed in microglia and participate in the communication between microglia and neurons, may play a role in this induction. This study investigated the potential roles of P2X7Rs in spinal LTP and persistent pain induced by TSS in rats. OxATP or BBG, a P2X7R antagonist, prevented the induction of spinal LTP both in vivo and in spinal cord slices in vitro and alleviated mechanical allodynia. Down-regulation of P2X7Rs with P2X7-siRNA blocked the induction of spinal LTP and inhibited mechanical allodynia. Double immunofluorescence showed colocalization of P2X7Rs with the microglial marker OX-42, but not with the astrocytic marker GFAP or the neuronal marker NeuN. Intrathecal injection of BBG suppressed the up-regulation of microglial P2X7Rs and increased expression of Fos in the spinal superficial dorsal horn. Further, pre-administration of BBG inhibited increased expression of the microglial marker Iba-1, phosphorylated p38 (p-p38), interleukin 1β (IL-1β) and GluR1 following TSS. Pre-administration of the IL-1 receptor antagonist (IL-1ra) blocked both the induction of spinal LTP and the up-regulation of GluR1. These results suggest that microglial P2X7Rs and its downstream signaling pathways play a pivotal role in the induction of spinal LTP and persistent pain induced by TSS.

  9. Maltodextrin and fat preference deficits in "taste-blind" P2X2/P2X3 knockout mice.

    Science.gov (United States)

    Sclafani, Anthony; Ackroff, Karen

    2014-07-01

    Adenosine triphosphate is a critical neurotransmitter in the gustatory response to the 5 primary tastes in mice. Genetic deletion of the purinergic P2X2/P2X3 receptor greatly reduces the neural and behavioral response to prototypical primary taste stimuli. In this study, we examined the behavioral response of P2X double knockout mice to maltodextrin and fat stimuli, which appear to activate additional taste channels. P2X double knockout and wild-type mice were given 24-h choice tests (vs. water) with ascending concentrations of Polycose and Intralipid. In Experiment 1, naive double knockout mice, unlike wild-type mice, were indifferent to dilute (0.5-4%) Polycose solutions but preferred concentrated (8-32%) Polycose to water. In a retest, the Polycose-experienced double knockout mice, like wild-type mice, preferred all Polycose concentrations. In Experiment 2, naive double knockout mice, unlike wild-type mice, were indifferent to dilute (0.313-2.5%) Intralipid emulsions but preferred concentrated (5-20%) Intralipid to water. In a retest, the fat-experienced double knockout mice, like wild-type mice, strongly preferred 0.313-5% Intralipid to water. These results indicate that the inherent preferences of mice for maltodextrin and fat are dependent upon adenosine triphosphate taste cell signaling. With experience, however, P2X double knockout mice develop strong preferences for the nontaste flavor qualities of maltodextrin and fat conditioned by the postoral actions of these nutrients.

  10. Extracellular ATP induces apoptosis through P2X7R activation in acute myeloid leukemia cells but not in normal hematopoietic stem cells

    Science.gov (United States)

    Salvestrini, Valentina; Orecchioni, Stefania; Talarico, Giovanna; Reggiani, Francesca; Mazzetti, Cristina; Bertolini, Francesco; Orioli, Elisa; Adinolfi, Elena; Virgilio, Francesco Di; Pezzi, Annalisa; Cavo, Michele

    2017-01-01

    Recent studies have shown that high ATP levels exhibit direct cytotoxic effects on several cancer cells types. Among the receptors engaged by ATP, P2×7R is the most consistently expressed by tumors. P2×7R is an ATP-gated ion channel that could drive the opening of a non-selective pore, triggering cell-death signal. We previously demonstrated that acute myeloid leukemia (AML) cells express high level of P2×7R. Here, we show that P2×7R activation with high dose ATP induces AML blast cells apoptosis. Moreover, P2×7R is also expressed on leukemic stem/progenitor cells (LSCs) which are sensitive to ATP-mediated cytotoxicity. Conversely, this cytotoxic effect was not observed on normal hematopoietic stem/progenitor cells (HSCs). Notably, the antileukemic activity of ATP was also observed in presence of bone marrow stromal cells and its addition to the culture medium enhanced cytosine arabinoside cytotoxicity despite stroma-induced chemoresistance. Xenotransplant experiments confirmed ATP antineoplastic activity in vivo. Overall, our results demonstrate that P2×7R stimulation by ATP induced a therapeutic response in AML at the LSC level while the normal stem cell compartment was not affected. These results provide evidence that ATP would be promising for developing innovative therapy for AML. PMID:27980223

  11. P2X7受体功能的调控%Regulation of P2X7 Receptor Function

    Institute of Scientific and Technical Information of China (English)

    张海燕; 郑国光

    2006-01-01

    P2X7受体是ATP门控的离子通道,对二价阳离子有较强的选择性.P2X7受体参与细胞信号转导,具有多种生理功能.其功能受胞外环境、配体水平调控;由受体表达变化、受体与配体结合、受体本身结构等多水平、多机制调节.P2X7受体与炎症、白血病等相关,阐明其功能调控有理论意义和潜在的应用前景.

  12. Composition law and nodal genus-2 curves in P$^{2}$

    CERN Document Server

    Katz, S; Ruan, Y; Katz, Sheldon; Qin, Zhenbo; Ruan, Yongbin

    1996-01-01

    Recently, there has been great interest in the application of composition laws to problems in enumerative geometry. Using the moduli space of stable maps, we compute the number of irreducible, reduced, nodal, degree-d genus-2 plane curves whose normalization has a fixed complex structure and which pass through 3d - 2 general points in \\Bbb P^2.

  13. Measurement and Analysis of P2P IPTV Program Resource

    Directory of Open Access Journals (Sweden)

    Wenxian Wang

    2014-01-01

    Full Text Available With the rapid development of P2P technology, P2P IPTV applications have received more and more attention. And program resource distribution is very important to P2P IPTV applications. In order to collect IPTV program resources, a distributed multi-protocol crawler is proposed. And the crawler has collected more than 13 million pieces of information of IPTV programs from 2009 to 2012. In addition, the distribution of IPTV programs is independent and incompact, resulting in chaos of program names, which obstructs searching and organizing programs. Thus, we focus on characteristic analysis of program resources, including the distributions of length of program names, the entropy of the character types, and hierarchy depth of programs. These analyses reveal the disorderly naming conventions of P2P IPTV programs. The analysis results can help to purify and extract useful information from chaotic names for better retrieval and accelerate automatic sorting of program and establishment of IPTV repository. In order to represent popularity of programs and to predict user behavior and popularity of hot programs over a period, we also put forward an analytical model of hot programs.

  14. P2P Domain Classification using Decision Tree

    CERN Document Server

    Ismail, Anis

    2011-01-01

    In Peer-to-Peer context, a challenging problem is how to find the appropriate peer to deal with a given query without overly consuming bandwidth? Different methods proposed routing strategies of queries taking into account the P2P network at hand. This paper considers an unstructured P2P system based on an organization of peers around Super-Peers that are connected to Super-Super- Peer according to their semantic domains; By analyzing the queries log file, a predictive model that avoids flooding queries in the P2P network is constructed after predicting the appropriate Super-Peer, and hence the peer to answer the query. A challenging problem in a schema-based Peer-to-Peer (P2P) system is how to locate peers that are relevant to a given query. In this paper, architecture, based on (Super-)Peers is proposed, focusing on query routing. The approach to be implemented, groups together (Super-)Peers that have similar interests for an efficient query routing method. In such groups, called Super-Super-Peers (SSP), Su...

  15. ATP, P2X receptors and pain pathways.

    Science.gov (United States)

    Ding, Y; Cesare, P; Drew, L; Nikitaki, D; Wood, J N

    2000-07-01

    A role for ATP in nociception and pain induction was proposed on the basis of human psychophysical experiments shortly after the formulation of the purinergic hypothesis. Following the pharmacological definition of distinct P2X and P2Y purinergic receptor subtypes by Burnstock and his collaborators, molecular cloning studies have identified the gene products that underlie the effects of ATP on peripheral sensory neurons. One particular receptor, P2X(3), is of particular interest in the context of pain pathways, because it is relatively selectively expressed at high levels by nociceptive sensory neurons. Evidence that this receptor may play a role in the excitation of sensory neurons has recently been complemented by studies that suggest an additional presynaptic role in the regulation of glutamate release from primary afferent neurons in the dorsal horn of the spinal cord. In this brief review, we discuss the present state of knowledge of the role of ATP in pain induction through its action on peripheral P2X receptors.

  16. The P2X7 Receptor-Interleukin-1 Liaison

    Science.gov (United States)

    Giuliani, Anna Lisa; Sarti, Alba C.; Falzoni, Simonetta; Di Virgilio, Francesco

    2017-01-01

    Interleukin-1β (IL-1β) plays a central role in stimulation of innate immune system and inflammation and in several chronic inflammatory diseases. These include rare hereditary conditions, e.g., auto-inflammatory syndromes, as well as common pathologies, such as type II diabetes, gout and atherosclerosis. A better understanding of IL-1β synthesis and release is particularly relevant for the design of novel anti-inflammatory drugs. One of the molecules mainly involved in IL-1β maturation is the P2X7 receptor (P2X7R), an ATP-gated ion channel that chiefly acts through the recruitment of the NLRP3 inflammasome-caspase-1 complex. In this review, we will summarize evidence supporting the key role of the P2X7R in IL-1β production, with special emphasis on the mechanism of release, a process that is still a matter of controversy. Four different models have been proposed: (i) exocytosis via secretory lysosomes, (ii) microvesicles shedding from plasma membrane, (iii) release of exosomes, and (iv) passive efflux across a leaky plasma membrane during pyroptotic cell death. All these models involve the P2X7R. PMID:28360855

  17. Comparing Pedophile Activity in Different P2P Systems

    Directory of Open Access Journals (Sweden)

    Raphaël Fournier

    2014-07-01

    Full Text Available Peer-to-peer (P2P systems are widely used to exchange content over the Internet. Knowledge of pedophile activity in such networks remains limited, despite having important social consequences. Moreover, though there are different P2P systems in use, previous academic works on this topic focused on one system at a time and their results are not directly comparable. We design a methodology for comparing KAD and eDonkey, two P2P systems among the most prominent ones and with different anonymity levels. We monitor two eDonkey servers and the KAD network during several days and record hundreds of thousands of keyword-based queries. We detect pedophile-related queries with a previously validated tool and we propose, for the first time, a large-scale comparison of pedophile activity in two different P2P systems. We conclude that there are significantly fewer pedophile queries in KAD than in eDonkey (approximately 0.09% vs. 0.25%.

  18. Measurement and Analysis of P2P IPTV Program Resource

    Science.gov (United States)

    Chen, Xingshu; Wang, Haizhou; Zhang, Qi

    2014-01-01

    With the rapid development of P2P technology, P2P IPTV applications have received more and more attention. And program resource distribution is very important to P2P IPTV applications. In order to collect IPTV program resources, a distributed multi-protocol crawler is proposed. And the crawler has collected more than 13 million pieces of information of IPTV programs from 2009 to 2012. In addition, the distribution of IPTV programs is independent and incompact, resulting in chaos of program names, which obstructs searching and organizing programs. Thus, we focus on characteristic analysis of program resources, including the distributions of length of program names, the entropy of the character types, and hierarchy depth of programs. These analyses reveal the disorderly naming conventions of P2P IPTV programs. The analysis results can help to purify and extract useful information from chaotic names for better retrieval and accelerate automatic sorting of program and establishment of IPTV repository. In order to represent popularity of programs and to predict user behavior and popularity of hot programs over a period, we also put forward an analytical model of hot programs. PMID:24772008

  19. 力竭运动对大鼠大脑P2X2、P2X4和P2X6受体表达的影响%Effect of Exhaustive Exercise on the Expression of Brain P2X2,P2X4,and P2X6 Receptors in Rats

    Institute of Scientific and Technical Information of China (English)

    周未艾; 李硕; 陈海涛

    2012-01-01

    目的:探讨一次和反复力竭游泳运动后大鼠大脑ATP受体P2X之三个亚型P2X2、P2X4和P2X6的时相性变化特点.方法:健康成年雄性SD大鼠68只,分为一次力竭游泳运动组和反复力竭游泳运动组及安静对照组,反复力竭组大鼠每日负重3%体重进行力竭游泳运动,共训练2周.运动组分别于力竭运动后即刻、4小时、12小时和24小时取材,采用实时荧光定量PCR方法测定力竭运动后大鼠P2X2、P2X4和P2X6受体亚型mRNA水平.结果:(1)反复力竭运动后12小时组P2X2相对表达率达到峰值,与反复力竭其它各组及安静对照组、一次力竭12小时组均有显著差异(P<0.01).(2)一次力竭即刻组P2X4相对表达率与安静对照组、4小时组、12小时组比较有显著统计学差异(分别为P< 0.01、P<0.05、P< 0.01).(3)反复力竭运动后12小时组P2X6相对表达率达到峰值.结论:3种受体亚型在一次力竭运动和反复力竭运动后12小时出现峰值或峰值趋势,提示在力竭运动后12小时,这3种P2X受体亚型所参与的中枢神经生理生化活动在此时可能会达到一个活跃期.%Objective The main purpose of this study is to investigate the variation in P2X2,P2X4 and P2X6 receptors in rats brain at different time points after single bout exhaustive exercise and repeated exhaustive exercise. Methods Sixty-eight male SD rats were divided randomly into the single bout exhaustive swimming group (SE), repeated exhausting swimming (RE), and sedentary group (C). The rats in group RE with weight-bearing 3% of body weight swan to exhaustion each day for a total of two weeks. The brain tissue of the rats was removed at 0 hr,4 hr,12 hr and 24 hr after the last exhaustive swimming. The mRNA levels of P2X2,P2X4 and P2X6 receptors in the brain tissue were observed through real-time quantitative PCR method. Results (l)The peak relative expression rate of the P2X2 in the group RE revealed at 12 hr after exhaustive

  20. BF-1--a novel selective 5-HT2B receptor antagonist blocking neurogenic dural plasma protein extravasation in guinea pigs.

    Science.gov (United States)

    Schmitz, Beate; Ullmer, Christoph; Segelcke, Daniel; Gwarek, Mirella; Zhu, Xin-Ran; Lübbert, Hermann

    2015-03-15

    Serotonin 5-HT2B receptor antagonists have been proposed as migraine prophylactic drugs, but previously available 5-HT2B receptor antagonists displayed multiple monoaminergic side effects and had to be withdrawn from the market. Here, we set out to identify a novel antagonist with high affinity and selectivity towards 5-HT2B receptors. To test the affinity of new compounds towards various receptors, we generated a broad series of cells functionally coupling human monoaminergic receptors to luciferase. Using the cell lines we revealed pimethixene (1-methyl-4-(9H-thioxanthen-9-ylidene)piperidine) as highly potent, albeit non-selective 5-HT2B receptor antagonist and optimized its chemical structure to create highly potent and selective 5-HT2B receptor antagonists. We selected the methoxythioxanthene BF-1 for further analysis. In comparison to pimethixene, it lacked high affinities to 5-HT1A, 5-HT2A, 5-HT2C, histamine H1, dopamine D1 and D2 as well as muscarinic M1 and M2 receptors. BF-1 was tested as potential migraine prophylactic drug by blocking meta-chlorophenylpiperazine, (mCPP) or BW723C86 (5-((thiophen-2-yl)methoxy)-α-methyltryptamine) induced neurogenic dural plasma protein extravasation in a guinea pig model that may resemble a migraine attack. BF-1 was significantly more potent in this assay compared to the well know non-selective 5-HT2B antagonists, methysergide ((6aR,9R)-N-[(2S)-1-Hydroxybutan-2-yl]-4,7-dimethyl-6,6a,8,9-tetrahydroindolo[4,3-fg]quinoline-9-carboxamide) or pizotifen (4-(1-methyl-4-piperidylidine)-9,10-dihydro-4H-benzo-[4,5]cyclohepta[1,2]-thiophene). Therefore, we propose BF-1 as a new compound that may be developed for prophylactic migraine treatment without the typical monoaminergic side effects.

  1. Diadenosine Homodinucleotide Products of ADP-ribosyl Cyclases Behave as Modulators of the Purinergic Receptor P2X7*

    Science.gov (United States)

    Bruzzone, Santina; Basile, Giovanna; Chothi, Madhu Parakkottil; Nobbio, Lucilla; Usai, Cesare; Jacchetti, Emanuela; Schenone, Angelo; Guse, Andreas H.; Di Virgilio, Francesco; De Flora, Antonio; Zocchi, Elena

    2010-01-01

    ADP-ribosyl cyclases from both vertebrates and invertebrates were previously shown to produce two isomers of P1,P2 diadenosine 5′,5′"-P1, P2-diphosphate, P18 and P24, from cyclic ADP-ribose (cADPR) and adenine. P18 and P24 are characterized by an unusual N-glycosidic linkage in one of the adenylic mononucleotides (Basile, G., Taglialatela-Scafati, O., Damonte, G., Armirotti, A., Bruzzone, S., Guida, L., Franco, L., Usai, C., Fattorusso, E., De Flora, A., and Zocchi, E. (2005) Proc. Natl. Acad. Sci. U.S.A. 102, 14509–14514). P24, but not P18, proved to increase the intracellular Ca2+ concentration ([Ca2+]i) in HeLa cells and to negatively affect mitochondrial function. Here we show that micromolar P24, but not P18, triggers a slow and sustained influx of extracellular Ca2+ through the opening of the purinergic receptor/channel P2X7. On the other hand, P18 inhibits the Ca2+ influx induced by 0.6 mm ATP in HEK293 cells stably transfected with P2X7, with an IC50 of ∼1 μm. Thus, P18 is devoid of intrinsic P2X7 stimulatory activity and behaves as an ATP antagonist. A P2X7-mediated increase of the basal [Ca2+]i has been demonstrated to negatively affect Schwann cell (SC) function in rats with the inherited, peripheral neuropathy Charcot-Marie-Tooth 1A (CMT1A) (Nobbio, L., Sturla, L., Fiorese, F., Usai, C., Basile, G., Moreschi, I., Benvenuto, F., Zocchi, E., De Flora, A., Schenone, A., and Bruzzone S. (2009) J. Biol. Chem. 284, 23146–23158). Preincubation of CMT1A SC with 200 nm P18 restored the basal [Ca2+]i to values similar to those recorded in wild-type SC. These results identify P18 as a new P2X7 antagonist, potentially useful in the treatment of CMT1A. PMID:20439466

  2. Diadenosine homodinucleotide products of ADP-ribosyl cyclases behave as modulators of the purinergic receptor P2X7.

    Science.gov (United States)

    Bruzzone, Santina; Basile, Giovanna; Chothi, Madhu Parakkottil; Nobbio, Lucilla; Usai, Cesare; Jacchetti, Emanuela; Schenone, Angelo; Guse, Andreas H; Di Virgilio, Francesco; De Flora, Antonio; Zocchi, Elena

    2010-07-02

    ADP-ribosyl cyclases from both vertebrates and invertebrates were previously shown to produce two isomers of P1,P2 diadenosine 5',5'"-P1, P2-diphosphate, P18 and P24, from cyclic ADP-ribose (cADPR) and adenine. P18 and P24 are characterized by an unusual N-glycosidic linkage in one of the adenylic mononucleotides (Basile, G., Taglialatela-Scafati, O., Damonte, G., Armirotti, A., Bruzzone, S., Guida, L., Franco, L., Usai, C., Fattorusso, E., De Flora, A., and Zocchi, E. (2005) Proc. Natl. Acad. Sci. U.S.A. 102, 14509-14514). P24, but not P18, proved to increase the intracellular Ca(2+) concentration ([Ca(2+)](i)) in HeLa cells and to negatively affect mitochondrial function. Here we show that micromolar P24, but not P18, triggers a slow and sustained influx of extracellular Ca(2+) through the opening of the purinergic receptor/channel P2X7. On the other hand, P18 inhibits the Ca(2+) influx induced by 0.6 mm ATP in HEK293 cells stably transfected with P2X7, with an IC(50) of approximately 1 mum. Thus, P18 is devoid of intrinsic P2X7 stimulatory activity and behaves as an ATP antagonist. A P2X7-mediated increase of the basal [Ca(2+)](i) has been demonstrated to negatively affect Schwann cell (SC) function in rats with the inherited, peripheral neuropathy Charcot-Marie-Tooth 1A (CMT1A) (Nobbio, L., Sturla, L., Fiorese, F., Usai, C., Basile, G., Moreschi, I., Benvenuto, F., Zocchi, E., De Flora, A., Schenone, A., and Bruzzone S. (2009) J. Biol. Chem. 284, 23146-23158). Preincubation of CMT1A SC with 200 nm P18 restored the basal [Ca(2+)](i) to values similar to those recorded in wild-type SC. These results identify P18 as a new P2X7 antagonist, potentially useful in the treatment of CMT1A.

  3. Properties of native P2X receptors in large multipolar neurons dissociated from rat hypothalamic arcuate nucleus.

    Science.gov (United States)

    Wakamori, Minoru; Sorimachi, Masaru

    2004-04-16

    ATP, the ligand of P2X receptors, is a candidate of neurotransmitter or co-transmitter in the peripheral and the central nervous systems. Anatomical studies have revealed the wide distribution of P2X receptors in the brain. So far, P2X-mediated small synaptic responses have been recorded in some brain regions. To determine the physiological significance of postsynaptic ATP receptors in the brain, we have investigated the P2X responses in rat dissociated hypothalamic arcuate neurons by using the patch-clamp technique. ATP evoked inward currents in a concentration-dependent manner (EC(50)=42 microM) at a holding potential of -70 mV. The current-voltage relationship showed a marked inward rectification starting around -10 mV. Although neither 300 microM alphabeta-methylene-ATP nor 300 microM betagamma-methylene-ATP induced any currents, 100 microM ATPgammaS and 100 microM 2-methylthio-ATP evoked inward currents of which amplitude was about 60% of the control currents evoked by 100 microM ATP. PPADS, one of P2 receptor antagonists, inhibited the ATP-evoked currents in a time- and a concentration-dependent manners (IC(50)=19 microM at 2 min). Permeant Ca(2+) inhibited the ATP-evoked currents in the range of millimolars (IC(50)=7 mM); however, Cd(2+) (1-300 microM), a broad cation channel blocker, facilitated the currents with slow off-response. Zn(2+) in the range of 1-100 microM facilitated the currents whereas Zn(2+) at the concentrations over 100 microM inhibited the currents. These observations suggest that functional P2X receptors are expressed in the hypothalamic arcuate nucleus. The most likely subunit combinations of the P2X receptors are P2X(2)-homomultimer and P2X(2)/P2X(6)-heteromultimer.

  4. Glutamate antagonists limit tumor growth

    OpenAIRE

    2001-01-01

    Neuronal progenitors and tumor cells possess propensity to proliferate and to migrate. Glutamate regulates proliferation and migration of neurons during development, but it is not known whether it influences proliferation and migration of tumor cells. We demonstrate that glutamate antagonists inhibit proliferation of human tumor cells. Colon adenocarcinoma, astrocytoma, and breast and lung carcinoma cells were most sensitive to the antiproliferative effect of the N...

  5. Theatrical distribution and P2P movie piracy: a survey of P2P networks in Hungary using transactional data

    NARCIS (Netherlands)

    Bodó, B.; Lakatos, Z.

    2012-01-01

    This article examines what appears to be the most important factor shaping file sharing: the failure of traditional cultural markets to efficiently supply the demand in the online environment. Its findings are based on tracking the traffic of movies on three Hungarian P2P networks. This dataset is t

  6. Theatrical distribution and P2P movie piracy: a survey of P2P networks in Hungary using transactional data

    NARCIS (Netherlands)

    Bodó, B.; Lakatos, Z.

    2012-01-01

    This article examines what appears to be the most important factor shaping file sharing: the failure of traditional cultural markets to efficiently supply the demand in the online environment. Its findings are based on tracking the traffic of movies on three Hungarian P2P networks. This dataset is t

  7. Assessment of mercury chloride-induced toxicity and the relevance of P2X7 receptor activation in zebrafish larvae.

    Science.gov (United States)

    Cruz, Fernanda Fernandes; Leite, Carlos Eduardo; Pereira, Talita Carneiro Brandão; Bogo, Maurício Reis; Bonan, Carla Denise; Battastini, Ana Maria Oliveira; Campos, Maria Martha; Morrone, Fernanda Bueno

    2013-09-01

    Zebrafish (Danio rerio) has been adopted as a model for behavioral, immunological and toxicological studies. Mercury is a toxic heavy metal released into the environment. There is evidence indicating that heavy metals can modulate ionotropic receptors, including the purinergic receptor P2X7. Therefore, this study evaluated the in vivo effects of acute exposure to mercury chloride (HgCl2) in zebrafish larvae and to investigate the involvement of P2X7R in mercury-related toxicity. Larvae survival was evaluated for 24 h after exposure to HgCl2, ATP or A740003. The combination of ATP (1 mM) and HgCl2 (20 μg/L) decreased survival when compared to ATP 1 mM. The antagonist A740003 (300 and 500 nM) increased the survival time, and reversed the mortality caused by ATP and HgCl2 in association. Quantitative real time PCR showed a decrease of P2X7R expression in the larvae treated with HgCl2 (20 μg/L). Evaluating the oxidative stress our results showed decreased CAT (catalase) activity and increased MDA (malondialdehyde) levels. Of note, the combination of ATP with HgCl2 showed an additive effect. This study provides novel evidence on the possible mechanisms underlying the toxicity induced by mercury, indicating that it is able to modulate P2X7R in zebrafish larvae.

  8. Functional expression of the damage-associated molecular pattern receptor P2X7 on canine kidney epithelial cells.

    Science.gov (United States)

    Jalilian, Iman; Spildrejorde, Mari; Seavers, Aine; Curtis, Belinda L; McArthur, Jason D; Sluyter, Ronald

    2012-12-15

    Epithelial cells are important in inflammation and immunity. In this study, we examined if Madin-Darby canine kidney (MDCK) epithelial cells express functional P2X7 receptors, which bind the damage-associated molecular pattern extracellular adenosine 5'-triphosphate (ATP). Reverse transcription (RT)-PCR and immunoblotting revealed the expression of P2X7 in MDCK cells. A flow cytometric assay demonstrated that ATP or 2'(3')-O-(4-benzoylbenzoyl)ATP induced ethidium(+) uptake into MDCK cells, and that this process was impaired by the P2X7 antagonists KN-62 and A438079. RT-PCR also demonstrated the presence of Toll-like receptor 4, NALP3, caspase-1, interleukin-1β and interleukin-18 in MDCK cells, as well as in positive control LPS-primed canine monocytes. In conclusion, the MDCK epithelial cell line expresses functional P2X7, as well as Toll-like receptor 4 and molecules associated with the NALP3 inflammasome. This cell line may help elucidate the role of these molecules in kidney epithelial cells and renal disorders in dogs and humans.

  9. Autocrine regulation of TGF-β1-induced cell migration by exocytosis of ATP and activation of P2 receptors in human lung cancer cells.

    Science.gov (United States)

    Takai, Erina; Tsukimoto, Mitsutoshi; Harada, Hitoshi; Sawada, Keisuke; Moriyama, Yoshinori; Kojima, Shuji

    2012-11-01

    TGF-β1 plays a key role in cancer progression through induction of various biological effects, including cell migration. Extracellular nucleotides, such as ATP, released from cells play a role in signaling through activation of P2 receptors. We show here that exocytosis of ATP followed by activation of P2 receptors play a key role in TGF-β1-induced actin remodeling associated with cell migration. Treatment with TGF-β1 facilitated migration of human lung cancer A549 cells, which was blocked by pretreatment with ecto-nucleotidase and P2 receptor antagonists. ATP and P2 agonists facilitated cell migration. TGF-β1-induced actin remodeling, which contributes to cell migration, was also suppressed by pretreatment with ecto-nucleotidase and P2 receptor antagonists. Knockdown of P2X7 receptor suppressed TGF-β1-induced migration and actin remodeling. These results indicate the involvement of TGF-β1-induced ATP release in cell migration, at least in part, through activation of P2X7 receptors. TGF-β1 caused release of ATP from A549 cells within 10 minutes. Both ATP-enriched vesicles and expression of a vesicular nucleotide transporter (VNUT) SLC17A9, which is responsible for exocytosis of ATP, were found in cytosol of A549 cells. TGF-β1 failed to induce release of ATP from SLC17A9-knockdown cells. TGF-β1-induced cell migration and actin remodeling were also decreased in SLC17A9-knockdown cells. These results suggest the importance of exocytosis of ATP in cell migration. We conclude that autocrine signaling through exocytosis of ATP and activation of P2 receptors is required for the amplification of TGF-β1-induced migration of lung cancer cells.

  10. MSPnet: MANAGEABLE SIP P2P MEDIA DISTRIBUTION SYSTEM

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The letter proposes a three-layer manageable media distribution network system architecture called MSPnet, which is based on Session Initiation Protocol[1] and Peer to Peer (SIP P2P)technology. MSPnet performs application-level structured DHT routing and resource location among domains and unstructured ones in domain. Except for media distribution, it can be used to support a variety of P2P applications, including video broadcasting, video on demand, VoIP, etc. MSPnet is composed of three layers, namely, the signal control layer, the management layer, and the media transportation layer. The MSPnet prototype consists of the SIP server, the management server, the media server, and the node User Agent (UA). Results from a prototype experiment in a large-scale Internet environment show that MSPnet is feasible, scalable and manageable.

  11. Mobile P2P Trusted On-Demand Video Streaming

    CERN Document Server

    Iyer, Thava; Rizvandi, Nikzad Babaii; Varghese, Benoy; Boreli, Roksana

    2012-01-01

    We propose to demonstrate a mobile server assisted P2P system for on-demand video streaming. Our proposed solution uses a combination of 3G and ad-hoc Wi-Fi connections, to enable mobile devices to download content from a centralised server in a way that minimises the 3G bandwidth use and cost. On the customised GUI, we show the corresponding reduction in 3G bandwidth achieved by increasing the number of participating mobile devices in the combined P2P and ad-hoc Wi- Fi network, while demonstrating the good video playout quality on each of the mobiles. We also demonstrate the implemented trust mechanism which enables mobiles to only use trusted adhoc connections. The system has been implemented on Android based smartphones.

  12. Supporting Seamless Mobility for P2P Live Streaming

    Directory of Open Access Journals (Sweden)

    Eunsam Kim

    2014-01-01

    Full Text Available With advent of various mobile devices with powerful networking and computing capabilities, the users' demand to enjoy live video streaming services such as IPTV with mobile devices has been increasing rapidly. However, it is challenging to get over the degradation of service quality due to data loss caused by the handover. Although many handover schemes were proposed at protocol layers below the application layer, they inherently suffer from data loss while the network is being disconnected during the handover. We therefore propose an efficient application-layer handover scheme to support seamless mobility for P2P live streaming. By simulation experiments, we show that the P2P live streaming system with our proposed handover scheme can improve the playback continuity significantly compared to that without our scheme.

  13. Supporting seamless mobility for P2P live streaming.

    Science.gov (United States)

    Kim, Eunsam; Kim, Sangjin; Lee, Choonhwa

    2014-01-01

    With advent of various mobile devices with powerful networking and computing capabilities, the users' demand to enjoy live video streaming services such as IPTV with mobile devices has been increasing rapidly. However, it is challenging to get over the degradation of service quality due to data loss caused by the handover. Although many handover schemes were proposed at protocol layers below the application layer, they inherently suffer from data loss while the network is being disconnected during the handover. We therefore propose an efficient application-layer handover scheme to support seamless mobility for P2P live streaming. By simulation experiments, we show that the P2P live streaming system with our proposed handover scheme can improve the playback continuity significantly compared to that without our scheme.

  14. The high-pressure compressibility of B12P2

    Science.gov (United States)

    Gao, Yang; Zhou, Mi; Wang, Haiyan; Ji, Cheng; Whiteley, C. E.; Edgar, J. H.; Liu, Haozhe; Ma, Yanzhang

    2017-03-01

    In situ high pressure synchrotron X-ray diffraction measurements were performed on icosahedral boron phosphide (B12P2) to 43.2 GPa. No structural phase transition occurs over this pressure range. The bulk modulus of B12P2 is KOT = 207 ± 7 GPa with pressure derivative of K'OT = 6.6 ± 0.8 . The structure is most compressible along the chain formed by phosphorus and boron atoms in the crystal structure. It is believed that the compressibility of boron-rich compounds at close to ambient pressure is determined by the boron icosahedral structure, while the inclusive atoms (both boron and non-boron) between the icosahedra determine the high-pressure compressibility and structure stability.

  15. Addressing the P2P Bootstrap Problem for Small Networks

    CERN Document Server

    Wolinsky, David Isaac; Boykin, P Oscar; Figueiredo, Renato

    2010-01-01

    P2P overlays provide a framework for building distributed applications consisting of few to many resources with features including self-configuration, scalability, and resilience to node failures. Such systems have been successfully adopted in large-scale services for content delivery networks, file sharing, and data storage. In small-scale systems, they can be useful to address privacy concerns and for network applications that lack dedicated servers. The bootstrap problem, finding an existing peer in the overlay, remains a challenge to enabling these services for small-scale P2P systems. In large networks, the solution to the bootstrap problem has been the use of dedicated services, though creating and maintaining these systems requires expertise and resources, which constrain their usefulness and make them unappealing for small-scale systems. This paper surveys and summarizes requirements that allow peers potentially constrained by network connectivity to bootstrap small-scale overlays through the use of e...

  16. 77AESW/EEV Emerging Technologies and P2 Efforts

    Science.gov (United States)

    2010-06-01

    2010 to 00-00-2010 4. TITLE AND SUBTITLE 77AESW/EEV Emerging Technologies and P2 Efforts 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM...Response Program Initiative (R2PI) AFRL/ML ManTech < 18 Mo Ref: http://www.ml.afrl.af. mil/ mlm /r2pi.html ~$6M /yr RRF- Rapid Response Funds PB

  17. P2P Networks with IP Based Communication

    OpenAIRE

    Anupriya Koneru; Krishna Prasad MHM

    2012-01-01

    P2P communities can be seen as truly Distributed Computing applications in which group members communicate with one another to exchange information. The authors consider security issues in Peer to Peer Networks. For secure exchange of data between the group members the authors present a cryptography protocol and an Identity mechanism which can able to check even the Trust of the Peers based on the available reputation information. The authors are encapsulating the reputations of both the prov...

  18. Sheaves on P2 and generalized Appell functions

    CERN Document Server

    Manschot, Jan

    2014-01-01

    A closed expression is given for the generating functions of (virtual) Poincar\\'e polynomials of moduli spaces of semi-stable sheaves on the projective plane $\\mathbb{P}^2$ with arbitrary rank and Chern classes. To classify and study these generating functions, the notion of Appell functions with signature $(n_+,n_-)$ is introduced. For $n_-=1$, these novel functions reduce to the known class of Appell functions with multiple variables or higher level.

  19. P2X7 Receptor and Polykarion Formation

    OpenAIRE

    Falzoni, Simonetta; Chiozzi, Paola; Ferrari, Davide; Buell, Gary; Di Virgilio, Francesco

    2000-01-01

    Cell fusion is a central phenomenon during the immune response that leads to formation of large elements called multinucleated giant cells (MGCs) of common occurrence at sites of granulomatous inflammation. We have previously reported on the involvement in this event of a novel receptor expressed to high level by mononuclear phagocytes, the purinergic P2X7 receptor. Herein, we show that blockade of this receptor by a specific monoclonal antibody prevents fusion in ...

  20. P2RX7 purinoceptor: a therapeutic target for ameliorating the symptoms of duchenne muscular dystrophy.

    Directory of Open Access Journals (Sweden)

    Anthony Sinadinos

    2015-10-01

    .038, diaphragm (p = 0.042, and heart muscles (p < 0.001. We show that the amelioration of symptoms was proportional to the extent of receptor depletion and that improvements were observed following administration of two P2RX7 antagonists (CK, p = 0.030 and p = 0.050 without any detectable side effects. However, approaches successful in animal models still need to be proved effective in clinical practice.These results are, to our knowledge, the first to establish that a single treatment can improve muscle function both short and long term and also correct cognitive impairment and bone loss in DMD model mice. The wide-ranging improvements reflect the convergence of P2RX7 ablation on multiple disease mechanisms affecting skeletal and cardiac muscles, inflammatory cells, brain, and bone. Given the impact of P2RX7 blockade in the DMD mouse model, this receptor is an attractive target for translational research: existing drugs with established safety records could potentially be repurposed for treatment of this lethal disease.

  1. BQP_p = PP for integer p > 2

    CERN Document Server

    Bebel, Joseph

    2011-01-01

    There's something really strange about quantum mechanics. It's not just that cats can be dead and alive at the same time, and that entanglement seems to violate the principle of locality; quantum mechanics seems to be what Aaronson calls "an island in theoryspace", because even slight perturbations to the theory of quantum mechanics seem to generate absurdities. In [Aar 04] and [Aar 05], he explores these perturbations and the corresponding absurdities in the context of computation. In particular, he shows that a quantum theory where the measurement probabilities are computed using p-norm instead of the standard 2-norm has the effect of blowing up the class BQP (the class of problems that can be efficiently solved on a quantum computer) to at least PP (the class of problems that can be solved in probabilistic polynomial time). He showed that PP \\subseteq BQP_p \\subseteq PSPACE for all constants p != 2, and that BQP_p = PP for even integers p > 2. Here, we show that this equality holds for all integers p > 2.

  2. Pure P2P mediation system: A mappings discovery approach

    Science.gov (United States)

    selma, El yahyaoui El idrissi; Zellou, Ahmed; Idri, Ali

    2015-02-01

    The information integration systems consist in offering a uniform interface to provide access to a set of autonomous and distributed information sources. The most important advantage of this system is that it allows users to specify what they want, rather than thinking about how to get the responses. The works realized in this area have particular leads to two major classes of integration systems: the mediation systems based on the paradigm mediator / adapter and peer to peer systems (P2P). The combination of both systems has led to a third type; is the mediation P2P systems. The P2P systems are large-scale systems, self-organized and distributed. They allow the resource management in a completely decentralized way. However, the integration of structured information sources, heterogeneous and distributed proves to be a complex problem. The objective of this work is to propose an approach to resolve conflicts and establish a mapping between the heterogeneous elements. This approach is based on clustering; the latter is to group similar Peers that share common information in the same subnet. Thus, to facilitate the heterogeneity, we introduced three additional layers of our hierarchy of peers: internal schema, external schema and Schema directory peer. We used linguistic techniques, and precisely the name correspondence technique, that is based on the similarity of names to propose a correspondence.

  3. Uniform Sampling for Directed P2P Networks

    Science.gov (United States)

    Hall, Cyrus; Carzaniga, Antonio

    Selecting a random peer with uniform probability across a peer-to-peer (P2P) network is a fundamental function for unstructured search, data replication, and monitoring algorithms. Such uniform sampling is supported by several techniques. However, current techniques suffer from sample bias and limited applicability. In this paper, we present a sampling algorithm that achieves a desired uniformity while making essentially no assumptions about the underlying P2P network. This algorithm, called doubly stochastic converge (DSC), iteratively adjusts the probabilities of crossing each link in the network during a random walk, such that the resulting transition matrix is doubly stochastic. DSC is fully decentralized and is designed to work on both directed and undirected topologies, making it suitable for virtually any P2P network. Our simulations show that DSC converges quickly on a wide variety of topologies, and that the random walks needed for sampling are short for most topologies. In simulation studies with FreePastry, we show that DSC is resilient to high levels of churn, while incurring a minimal sample bias.

  4. Variations of $P_2$ in subpulse drifting pulsars

    CERN Document Server

    Yuen, R; Samsuddin, M A; Tu, Z Y; Han, X H

    2016-01-01

    We develop a model for subpulse separation period, $P_2$, taking into account both the apparent motion of the visible point as a function of pulsar phase, $\\psi$, and the possibility of abrupt jumps between different rotation states in non-corotating pulsar magnetospheres. We identify three frequencies: (i) the spin frequency of the star, (ii) the drift frequency of the magnetospheric plasma in the source region, and (iii) the angular frequency of the visible point around its trajectory. We show how the last of these, which is neglected in traditional models by implicitly assuming the line of sight through the center of the star, affects the interpretation of $P_2$. We attribute the subpulse structure to emission from $m$ anti-nodes distributed uniformly in azimuthal angle about the magnetic axis. We show that variations of $P_2$ as a function of rotational phase or observing frequency arise naturally when the motion of the visible point is taken into account. We discuss possible application of our model in s...

  5. Arg333 and Arg334 in the COOH terminus of the human P2Y1 receptor are crucial for Gq coupling.

    Science.gov (United States)

    Ding, Zhongren; Tuluc, Florin; Bandivadekar, Kavita R; Zhang, Lili; Jin, Jianguo; Kunapuli, Satya P

    2005-03-01

    The P2Y(1) ADP receptor activates G(q) and causes increases in intracellular Ca(2+) concentration through stimulation of PLC. In this study, we investigated the role of the amino acid residues in the COOH terminus of the human P2Y(1) receptor in G(q) activation. Stimulation of Chinese hamster ovary (CHO-K1) cells stably expressing the wild-type human P2Y(1) receptor (P2Y(1)-WT cells), P2Y(1)-DeltaR340-L373, or P2Y(1)-DeltaD356-L373 with 2-methylthio-ADP (2-MeSADP) caused inositol phosphate production. In contrast, cells expressing P2Y(1)-DeltaT330-L373, a mutant lacking the entire COOH terminus, completely lost their response to 2-MeSADP. Similar data were obtained by using these cell lines and measuring Ca(2+) mobilization upon stimulation with 2-MeSADP, indicating that the 10 amino acids (330TFRRRLSRAT339) in the COOH terminus of the human P2Y(1) receptor are essential for G(q) coupling. Radioligand binding demonstrated that both the P2Y(1)-WT and P2Y(1)-DeltaT330-L373-expressing cells have almost equal binding of [(3)H]MRS2279, a P2Y(1) receptor antagonist, indicating that COOH-terminal truncation did not drastically affect the conformation of the receptor. CHO-K1 cells expressing a chimeric P2Y(12) receptor with the P2Y(1) COOH terminus failed to elicit G(q) functional responses, indicating that the P2Y(1) COOH terminus is essential but not sufficient for G(q) activation. Finally, cells expressing a double-mutant P2Y(1) receptor (R333A/R334A) in the conserved BBXXB region of the COOH terminus of the G(q)-activating P2Y receptors completely lost their functional ability to activate G(q). We conclude that the two arginine residues (R333R334) in the COOH terminus of the human P2Y(1) receptor are essential for G(q) coupling.

  6. Quantitative structure–activity relationship study of P2X7 receptor inhibitors using combination of principal component analysis and artificial intelligence methods

    Science.gov (United States)

    Ahmadi, Mehdi; Shahlaei, Mohsen

    2015-01-01

    P2X7 antagonist activity for a set of 49 molecules of the P2X7 receptor antagonists, derivatives of purine, was modeled with the aid of chemometric and artificial intelligence techniques. The activity of these compounds was estimated by means of combination of principal component analysis (PCA), as a well-known data reduction method, genetic algorithm (GA), as a variable selection technique, and artificial neural network (ANN), as a non-linear modeling method. First, a linear regression, combined with PCA, (principal component regression) was operated to model the structure–activity relationships, and afterwards a combination of PCA and ANN algorithm was employed to accurately predict the biological activity of the P2X7 antagonist. PCA preserves as much of the information as possible contained in the original data set. Seven most important PC's to the studied activity were selected as the inputs of ANN box by an efficient variable selection method, GA. The best computational neural network model was a fully-connected, feed-forward model with 7−7−1 architecture. The developed ANN model was fully evaluated by different validation techniques, including internal and external validation, and chemical applicability domain. All validations showed that the constructed quantitative structure–activity relationship model suggested is robust and satisfactory. PMID:26600858

  7. Quantitative structure-activity relationship study of P2X7 receptor inhibitors using combination of principal component analysis and artificial intelligence methods.

    Science.gov (United States)

    Ahmadi, Mehdi; Shahlaei, Mohsen

    2015-01-01

    P2X7 antagonist activity for a set of 49 molecules of the P2X7 receptor antagonists, derivatives of purine, was modeled with the aid of chemometric and artificial intelligence techniques. The activity of these compounds was estimated by means of combination of principal component analysis (PCA), as a well-known data reduction method, genetic algorithm (GA), as a variable selection technique, and artificial neural network (ANN), as a non-linear modeling method. First, a linear regression, combined with PCA, (principal component regression) was operated to model the structure-activity relationships, and afterwards a combination of PCA and ANN algorithm was employed to accurately predict the biological activity of the P2X7 antagonist. PCA preserves as much of the information as possible contained in the original data set. Seven most important PC's to the studied activity were selected as the inputs of ANN box by an efficient variable selection method, GA. The best computational neural network model was a fully-connected, feed-forward model with 7-7-1 architecture. The developed ANN model was fully evaluated by different validation techniques, including internal and external validation, and chemical applicability domain. All validations showed that the constructed quantitative structure-activity relationship model suggested is robust and satisfactory.

  8. Neuronal Release of Cytokine IL-3 Triggered by Mechanosensitive Autostimulation of the P2X7 Receptor Is Neuroprotective

    Science.gov (United States)

    Lim, Jason C.; Lu, Wennan; Beckel, Jonathan M.; Mitchell, Claire H.

    2016-01-01

    Mechanical strain due to increased pressure or swelling activates inflammatory responses in many neural systems. As cytokines and chemokine messengers lead to both pro-inflammatory and neuroprotective actions, understanding the signaling patterns triggered by mechanical stress may help improve overall outcomes. While cytokine signaling in neural systems is often associated with glial cells like astrocytes and microglia, the contribution of neurons themselves to the cytokine response is underappreciated and has bearing on any balanced response. Mechanical stretch of isolated neurons was previously shown to trigger ATP release through pannexin hemichannels and autostimulation of P2X7 receptors (P2X7Rs) on the neural membrane. Given that P2X7Rs are linked to cytokine activation in other cells, this study investigates the link between neuronal stretch and cytokine release through a P2X7-dependent pathway. Cytokine assays showed application of a 4% strain to isolated rat retinal ganglion cells (RGCs) released multiple cytokines. The P2X7R agonist BzATP also released multiple cytokines; Interleukin 3 (IL-3), TNF-α, CXCL9, VEGF, L-selectin, IL-4, GM-CSF, IL-10, IL-1Rα, MIP and CCL20 were released by both stimuli, with the release of IL-3 greatest with either stimuli. Stretch-dependent IL-3 release was confirmed with ELISA and blocked by P2X7R antagonists A438079 and Brilliant Blue G (BBG), implicating autostimulation of the P2X7R in stretch-dependent IL-3 release. Neuronal IL-3 release triggered by BzATP required extracellular calcium. The IL-3Rα receptor was expressed on RGCs but not astrocytes, and both IL-3Rα and IL-3 itself were predominantly expressed in the retinal ganglion cell layer of adult retinal sections, implying autostimulation of receptors by released IL-3. While the number of surviving ganglion cells decreased with time in culture, the addition of IL-3 protected against this loss of neurons. Expression of mRNA for IL-3 and IL-3Rα increased in rat

  9. Neuronal release of cytokine IL-3 triggered by mechanosensitive autostimulation of the P2X7 receptor is neuroprotective

    Directory of Open Access Journals (Sweden)

    Jason C Lim

    2016-11-01

    Full Text Available Mechanical strain due to increased pressure or swelling activates inflammatory responses in many neural systems. As cytokines and chemokine messengers lead to both pro-inflammatory and neuroprotective actions, understanding the signaling patterns triggered by mechanical stress may help improve overall outcomes. While cytokine signaling in neural systems is often associated with glial cells like astrocytes and microglia, the contribution of neurons themselves to the cytokine response is underappreciated and has bearing on any balanced response. Mechanical stretch of isolated neurons was previously shown to trigger ATP release through pannexin hemichannels and autostimulation of P2X7 receptors (P2X7Rs on the neural membrane. Given that P2X7Rs are linked to cytokine activation in other cells, this study investigates the link between neuronal stretch and cytokine release through a P2X7-dependent pathway. Cytokine assays showed application of a 4% strain to isolated rat retinal ganglion cells (RGCs released multiple cytokines. The P2X7R agonist BzATP also released multiple cytokines; IL-3, TNF-α, CXCL9, VEGF, L-selectin, IL-4, GM-CSF, IL-10, IL-1Rα, MIP and CCL20 were released by both stimuli, with the release of IL-3 greatest with either stimulus. Stretch-dependent IL-3 release was confirmed with ELISA and blocked by P2X7R antagonists A438079 and Brilliant Blue G (BBG, implicating autostimulation of the P2X7R in stretch-dependent IL-3 release. Neuronal IL-3 release triggered by BzATP required extracellular calcium. The IL-3Rα receptor was expressed on retinal ganglion cells but not astrocytes, and both IL-3Rα and IL-3 itself were predominantly expressed in the retinal ganglion cell layer of adult retinal sections, implying autostimulation of receptors by released IL-3. While the number of surviving ganglion cells decreased with time in culture, addition of IL-3 protected against this loss of neurons. Expression of mRNA for IL-3 and IL-3R

  10. Activation of P2X7 receptors in the midbrain periaqueductal gray of rats facilitates morphine tolerance.

    Science.gov (United States)

    Xiao, Zhi; Li, You-Yan; Sun, Meng-Jie

    2015-08-01

    Opiates such as morphine exhibit analgesic effect in various pain models, but repeated and chronic morphine administration may develop resistance to antinociception. The purinergic signaling system is involved in the mechanisms of pain modulation and morphine tolerance. This study aimed to determine whether the P2X7 receptor in the ventrolateral midbrain periaqueductal gray (vlPAG) is involved in morphine tolerance. Development of tolerance to the antinociceptive effect of morphine was induced in normal adult male Sprague-Dawley (SD) rats through subcutaneous injection of morphine (10mg/kg). The analgesic effect of morphine (5mg/kg, i.p.) was assessed by measuring mechanical withdrawal thresholds (MWTs) in rats with an electronic von Frey anesthesiometer. The expression levels and distribution of the P2X7 receptor in the vlPAG was evaluated through Western blot analysis and immunohistochemistry. The acute effects of intra-vlPAG injection of the selective P2X7 receptor agonist Bz-ATP, the selective P2X7 receptor antagonist A-740003, or antisense oligodeoxynucleotide (AS ODN) targeting the P2X7 receptor on morphine-treated rats were also observed. Results demonstrated that repeated morphine administration decreased the mechanical pain thresholds. By contrast, the expression of the P2X7 receptor protein was up-regulated in the vlPAG in morphine tolerant rats. The percent changes in MWT were markedly but only transiently attenuated by intra-vlPAG injection of Bz-ATP (9nmol/0.3μL) but elevated by A-740003 at doses of 10 and 100nmol/0.3μL. AS ODN (15nmol/0.3μL) against the P2X7 receptor reduced the development of chronic morphine tolerance in rats. These results suggest that the development of antinociceptive tolerance to morphine is partially mediated by activating the vlPAG P2X7 receptors. The present data also suggest that the P2X7 receptors may be a therapeutic target for improving the analgesic effect of morphine in treatments of pain when morphine tolerance

  11. SP 01-3 ALDOSTERONE ANTAGONISTS IN HEART FAILURE.

    Science.gov (United States)

    Johnston, Colin

    2016-09-01

    Aldosterone's deleterious pathophysiological effects on the cardiovascular system if blocked by mineralcorticord antagonists (MRAs) logically should lead to improvement in heart function and outcomes in heart failure (HF). The first trial to test this hypothesis was tthe RALES trial in 1999 which treated patients with class III-IV HF with spironolactone. It showed significant reduction in mortality and cardiovascular hospitalzation rates. This was confirmed & extended in EMHASIS-HF RCT with classs II-III being treated with ACEIs & BB who received placebo or elperinone (a MRA) with again a statistically significant fall in mortality & hospitalization.The possible cardioprotective effects of MRA post acute myocardial infarct (MI) is less clear. The EPHESUS RCT in 2003 demostrated that elperinone given 3-14 days AMI in patients with early signs of HF reduced mortality & morbidity. However in the ALBTROSS trial using spironolactone 2 days after AMI showed no benfit in patients without HF but in a subgroup with ST elevation there was a 80% reduction in mortality after 6 months. However a recent meta-analysis from 25 RCT with data invovling 19,333 patients with either HF or post MI assigned aldosterone antagonists (AA)or placebo showed a 18% reduction in mortality including a 20% fall in CV mortality and a 19% reduction in SCD.The role of AA in HFPEF is even even more contraversial. The TOPCAT RCT of 3445 patients with symptomatc HFPEF randomised to spironolactone failed to meet the primary composite end point of death, aborted cardiac arrest or hospitalization although there was a reduction in hospitalization for HF (HR 0.83 P = 0.04).The differences between selective or non-selective MRAs, their ADRs & off target effects will also be discussed.

  12. Distribution of P2Y2 receptors in the guinea pig enteric nervous system and its coexistence with P2X2 and P2X3 receptors, neuropeptide Y, nitric oxide synthase and calretinin.

    Science.gov (United States)

    Xiang, Zhenghua; Burnstock, Geoffrey

    2005-11-01

    The distribution of P2Y2 receptor-immunoreactive (ir) neurons and fibers and coexistence of P2Y2 with P2X2 and P2X3 receptors, neuropeptide Y (NPY), calretinin (CR), calbindin (CB) and nitric oxide synthase (NOS) was investigated with immunostaining methods. The results showed that P2Y2-ir neurons and fibers were distributed widely in myenteric and submucous plexuses of the guinea pig stomach corpus, jejunum, ileum and colon. The typical morphology of P2Y2-ir neurons was a long process with strong positive staining on the same side of the cell body. The P2Y2-ir neurons could be Dogiel type 1. About 40-60% P2X3-ir neurons were immunoreactive for P2Y2 in the myenteric plexus and all the P2X3-ir neurons expressed the P2Y2 receptor in the submucosal plexus; almost all the NPY-ir neurons and the majority of CR-ir neurons were also immunoreactive for P2Y2, especially in the myenteric plexus of the small intestine; no P2Y2-ir neurons were immunoreactive for P2X2 receptors, CB and NOS. It is shown for the first time that S type/Dogiel type 1 neurons with fast P2X and slow P2Y receptor-mediated depolarizations could be those neurons expressing both P2Y2-ir and P2X3-ir and that they are widely distributed in myenteric and submucosal plexuses of guinea pig gut.

  13. Nucleus of the active Centaur C/2011 P2 (PANSTARRS)

    Science.gov (United States)

    Mazzotta Epifani, E.; Perna, D.; Dotto, E.; Palumbo, P.; Dall'Ora, M.; Micheli, M.; Ieva, S.; Perozzi, E.

    2017-01-01

    Aims: In this paper we present observations of the active Centaur C/2011 P2 (PANSTARRS), showing a compact comet-like coma at the heliocentric distance of rh = 9 au. The observations were obtained in the framework of a wider program on Centaurs aimed at searching for comet-like activity in several targets outside Jupiter's aphelion. Methods: We analysed visible images of the Centaur taken at the TNG telescope in the R filter to investigate the level of coma contributing to the target brightness and to derive information on its nucleus size. Results: Centaur C/2011 P2 (PANSTARRS) shows a faint but still detectable comet-like activity, which accounts for more than 50% to the observed brightness. The coma contribution has been subtracted in order to derive an estimate for the Centaur's diameter of D 16 km, assuming an albedo of A = 0.07 (average of albedo measured within the Centaur group). The results for Centaur C/2011 P2 (PANSTARRS) fit in the general picture of the group: Centaurs with smaller perihelion distance q and semi-major axis a are smaller than those remaining farther from the Sun during their orbital path, thus reinforcing the idea that active Centaurs are "comets in fieri". Based on observations collected at the Telescopio Nazionale Galileo (TNG), operated on the island of La Palma by the Centro Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.

  14. Final Design of the SLAC P2 Marx Klystron Modulator

    Energy Technology Data Exchange (ETDEWEB)

    Kemp, M.A.; Benwell, A.; Burkhart, C.; Larsen, R.; MacNair, D.; Nguyen, M.; Olsen, J.; /SLAC

    2011-11-08

    The SLAC P2 Marx has been under development for two years, and follows on the P1 Marx as an alternative to the baseline klystron modulator for the International Linear Collider. The P2 Marx utilizes a redundant architecture, air-insulation, a control system with abundant diagnostic access, and a novel nested droop correction scheme. This paper is an overview of the design of this modulator. There are several points of emphasis for the P2 Marx design. First, the modulator must be compatible with the ILC two-tunnel design. In this scheme, the modulator and klystron are located within a service tunnel with limited access and available footprint for a modulator. Access to the modulator is only practical from one side. Second, the modulator must have high availability. Robust components are not sufficient alone to achieve availability much higher than 99%. Therefore, redundant architectures are necessary. Third, the modulator must be relatively low cost. Because of the large number of stations in the ILC, the investment needed for the modulator components is significant. High-volume construction techniques which take advantage of an economy of scale must be utilized. Fourth, the modulator must be simple and efficient to maintain. If a modulator does become inoperable, the MTTR must be small. Fifth, even though the present application for the modulator is for the ILC, future accelerators can also take advantage of this development effort. The hardware, software, and concepts developed in this project should be designed such that further development time necessary for other applications is minimal.

  15. MODELLING THE P2Y PURINOCEPTOR USING RHODOPSIN AS TEMPLATE

    Science.gov (United States)

    Van Rhee, A. Michiel; Fischer, Bilha; Van Galen, Philip J. M.; Jacobson, Kenneth A.

    2012-01-01

    The P2Y1 purinoceptor cloned from chick brain (Webb, T. et al. (1993) FEBS Lett., 324, 219–225) is a 362 amino acid, 41 kDa protein. To locate residues tentatively involved in ligand recognition a molecular model of the P2Y purinoceptor has been constructed. The model was based on the primary sequence and structural homology with the G-protein coupled photoreceptor rhodopsin, in analogy to the method proposed by Ballesteros and Weinstein ((1995) Meth. Neurosci. 25, 366–428). Transmembrane helices were constructed from the amino acid sequence, minimized individually, and positioned in a helical bundle. The helical bundle was then minimized using the Amber forcefield in Discover (BIOSYM Technologies) to obtain the final model. Several residues that have been shown to be critical in ligand binding in other GPCRs are conserved in the P2Y1 purinoceptor. According to our model the side chains of these conserved residues are facing the internal cleft in which ligand binding likely occurs. The model also suggests four basic residues (H121 in TM3, H266 and K269 in TM6 and R299 in TM7) near the extracellular surface that might be involved in ligand binding. These basic residues might be essential in coordinating the triphosphate chain of the endogenous ligand adenosine 5′-triphosphate (ATP). Potential binding sites for agonists have been explored by docking several derivatives (including newly synthesized N6-derivatives) into the model. The N6-phenylethyl substituent is tolerated pharmacologically, and in our model this substituent occupies a region predominantly defined by aromatic residues such as F51 (TM1), Y100 (TM2) and F120 (TM3). The dimethylated analogue of ATP, N6,N6-dimethyl-adenosine 5′-triphosphate, is less well tolerated pharmacologically, and our model predicts that the attenuated activity is due to interference with hydrogen bonding capacity to Q296 (TM7). PMID:8872457

  16. Muscarinic Receptor Agonists and Antagonists

    Directory of Open Access Journals (Sweden)

    David R. Kelly

    2001-02-01

    Full Text Available A comprehensive review of pharmacological and medical aspects of the muscarinic class of acetylcholine agonists and antagonists is presented. The therapeutic benefits of achieving receptor subtype selectivity are outlined and applications in the treatment of Alzheimer’s disease are discussed. A selection of chemical routes are described, which illustrate contemporary methodology for the synthesis of chiral medicinal compounds (asymmetric synthesis, chiral pool, enzymes. Routes to bicyclic intrannular amines and intramolecular Diels-Alder reactions are highlighted.

  17. Randomized trial of switching from prescribed non-selective non-steroidal anti-inflammatory drugs to prescribed celecoxib

    DEFF Research Database (Denmark)

    Macdonald, Thomas M; Hawkey, Chris J; Ford, Ian;

    2016-01-01

    BACKGROUND: Selective cyclooxygenase-2 inhibitors and conventional non-selective non-steroidal anti-inflammatory drugs (nsNSAIDs) have been associated with adverse cardiovascular (CV) effects. We compared the CV safety of switching to celecoxib vs. continuing nsNSAID therapy in a European setting...... primary events per 1000 patient-years exposure. There were only 15 adjudicated secondary upper gastrointestinal complication endpoints (0.078/100 patient-years on celecoxib vs. 0.053 on nsNSAIDs OT, 0.078 vs. 0.053 ITT). More gastrointestinal serious adverse reactions and haematological adverse reactions...

  18. Broadband terahertz pulse emission from ZnGeP_2

    Science.gov (United States)

    Rowley, J. D.; Pierce, J. K.; Brant, A. T.; Halliburton, L. E.; Giles, N. C.; Schunemann, P. G.; Bristow, A. D.

    2012-03-01

    Optical rectification is demonstrated in (110)-cut ZnGeP_2 (ZGP) providing broadband terahertz (THz) generation. The source is compared to both GaP and GaAs over a wavelength range of 1150 nm to 1600 nm and peak intensity range of 0.5 GW/cm^2 to 40 GW/cm^2. ZGP peak-to-peak field amplitude is larger than in the other materials due to either lower nonlinear absorption or larger second order nonlinearity. This material is well suited for broadband THz generation across a wide range of infrared excitation wavelengths.

  19. P2P流行意味着IPTV末落?

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    十年前微软Venus计划启动了IPTV,的进程,随时随地点播音视频是当初IPTV的梦想,十年后随着宽带的普及,没有人想到在中国P2P居然占据了一半以上的带宽,IPTV还没有普及就有消亡的危险,毕竟随时随地已经实现了。

  20. Role of 2p-2h MEC excitations in superscaling

    Energy Technology Data Exchange (ETDEWEB)

    De Pace, A. E-mail: depace@to.infn.it; Nardi, M.; Alberico, W.M.; Donnelly, T.W.; Molinari, A

    2004-09-06

    Following recent studies of inclusive electron scattering from nuclei at high energies which focused on two-nucleon emission mediated by meson-exchange currents, in this work the superscaling behavior of such contributions is investigated. Comparisons are made with existing data below the quasielastic peak where at high momentum transfers scaling of the second kind is known to be excellent and scaling of the first kind is good, in the proximity of the peak where both 1p-1h and 2p-2h contributions come into play, and above the peak where inelasticity becomes important and one finds scaling violations of the two kinds.

  1. Random walk search in unstructured P2P

    Institute of Scientific and Technical Information of China (English)

    Jia Zhaoqing; You Jinyuan; Rao Ruonan; Li Minglu

    2006-01-01

    Unstructured P2P has power-law link distribution, and the random walk in power-law networks is analyzed. The analysis results show that the probability that a random walker walks through the high degree nodes is high in the power-law network, and the information on the high degree nodes can be easily found through random walk. Random walk spread and random walk search method (RWSS) is proposed based on the analysis result. Simulation results show that RWSS achieves high success rates at low cost and is robust to high degree node failure.

  2. Efficient Search in P2P File Sharing System

    Institute of Scientific and Technical Information of China (English)

    Xiao Bo; Jin Wei; Hou Mengshu

    2006-01-01

    A new routing algorithm of peer-to-peer file sharing system with routing indices was proposed, in which a node forwards a query to neighbors that are more likely to have answers based on its statistics. The proposed algorithm was tested by creating a P2P simulator and varying the input parameters, and was compared to the search algorithms using flooding (FLD) and random walk (RW). The result shows that with the proposed design, the queries are routed effectively, the network flows are reduced remarkably, and the peer-to-peer file sharing system gains a good expansibility.

  3. Recombinant P2Y receptors: the UCL experience.

    Science.gov (United States)

    King, B F; Townsend-Nicholson, A

    2000-07-01

    The beginning of the last decade heralded three important and sequential developments in our understanding of cell-to-cell signalling by extracellular ATP via its cell surface receptors, the P2 purinoceptors. One major development in ATP signalling culminated in a timely review in 1991, when it was established in the clearest of terms that ATP receptors exploited discrete signal transduction pathways (Dubyak, G.R., 1991. Signal transduction by P2-purinergic receptors for extracellular ATP. Am. J. Respir. Cell. Mol. Biol. 4, 295-300; and later in Dubyak, G.R., El-Moatassim, C., 1993. Signal transduction via P2-purinergic receptors for extracellular ATP and other nucleotides. Am. J. Physiol. 265, C577-C606). Henceforth, it was universally acknowledged that some P2 purinoceptors interacted with heterotrimeric G-proteins to activate intracellular signalling cascades (metabotropic ATP receptors), whereas others contained intrinsic ion-channels (ionotropic ATP receptors). A second key development can be traced to 1992, from the discovery that ATP receptors were involved in excitatory neurotransmission in the CNS and PNS (Edwards, F.A., Gibb, A.J., Colquhoun, D., 1992. ATP receptor-mediated synaptic currents in the central nervous system. Nature 359, 144-147; Evans, R.J., Derkach, V., Surprenant, A., 1992. ATP mediates fast synaptic transmission in mammalian neurons. Nature 357, 503-505; Silinsky, E.M., Gerzanich, V., Vanner, S.M., 1992. ATP mediates excitatory synaptic transmission in mammalian neurones. Br. J. Pharmacol., 106, 762-763). Thereafter, it was accepted that ATP could play a neurotransmitter and/or modulatory role throughout the entire nervous system. The third key development stemmed from the isolation of a cDNA, from chick brain, encoding a metabotropic ATP receptor (Webb, T.E., Simon, J., Krishek, B.J., Bateson, A.N., Smart, T.G., King, B.F., Burnstock, G., Barnard, E.A., 1993. Cloning and functional expression of a brain G-protein-coupled ATP receptor

  4. Problems and progress: survey on fat points in P2

    OpenAIRE

    Harbourne, Brian

    2001-01-01

    This paper surveys certain problems involving numerical characters for ideals I(Z) defining fat points subschemes $Z=m_1p_1+...+m_np_n$ for general points $p_i\\in {\\bf P}^2$. It also presents some new results, and includes a suite of MACAULAY 2 scripts for computing actual or conjectured values of (or bounds on) these characters. One such script, for example, is findres, which implements an algorithm due to Fitchett, Harbourne and Holay for computing the syzygy modules in a minimal free resol...

  5. P2X7 receptors in satellite glial cells mediate high functional expression of P2X3 receptors in immature dorsal root ganglion neurons

    Directory of Open Access Journals (Sweden)

    Chen Yong

    2012-02-01

    Full Text Available Abstract Background The purinergic P2X3 receptor (P2X3R expressed in the dorsal root ganglion (DRG sensory neuron and the P2X7 receptor (P2X7R expressed in the surrounding satellite glial cell (SGC are two major receptors participating in neuron-SGC communication in adult DRGs. Activation of P2X7Rs was found to tonically reduce the expression of P2X3Rs in DRGs, thus inhibiting the abnormal pain behaviors in adult rats. P2X receptors are also actively involved in sensory signaling in developing rodents. However, very little is known about the developmental change of P2X7Rs in DRGs and the interaction between P2X7Rs and P2X3Rs in those animals. We therefore examined the expression of P2X3Rs and P2X7Rs in postnatal rats and determined if P2X7R-P2X3R control exists in developing rats. Findings We immunostained DRGs of immature rats and found that P2X3Rs were expressed only in neurons and P2X7Rs were expressed only in SGCs. Western blot analyses indicated that P2X3R expression decreased while P2X7R expression increased with the age of rats. Electrophysiological studies showed that the number of DRG neurons responding to the stimulation of the P2XR agonist, α,β-meATP, was higher and the amplitudes of α,β-meATP-induced depolarizations were larger in immature DRG neurons. As a result, P2X3R-mediated flinching responses were much more pronounced in immature rats than those found in adult rats. When we reduced P2X7R expression with P2X7R-siRNA in postnatal and adult rats, P2X3R-mediated flinch responses were greatly enhanced in both rat populations. Conclusions These results show that the P2X7R expression increases as rats age. In addition, P2X7Rs in SGCs exert inhibitory control on the P2X3R expression and function in sensory neurons of immature rats, just as observed in adult rats. Regulation of P2X7R expression is likely an effective way to control P2X3R activity and manage pain relief in infants.

  6. Constructing an atomic-resolution model of human P2X7 receptor followed by pharmacophore modeling to identify potential inhibitors.

    Science.gov (United States)

    Ahmadi, Mehdi; Nowroozi, Amin; Shahlaei, Mohsen

    2015-09-01

    The P2X purinoceptor 7 (P2X7R) is a trimeric ATP-activated ion channel gated by extracellular ATP. P2X7R has important role in numerous diseases including pain, neurodegeneration, and inflammatory diseases such as rheumatoid arthritis and osteoarthritis. In this prospective, the discovery of small-molecule inhibitors for P2X7R as a novel therapeutic target has received considerable attention in recent years. At first, 3D structure of P2X7R was built by using homology modeling (HM) and a 50ns molecular dynamics simulation (MDS). Ligand-based quantitative pharmacophore modeling methodology of P2X7R antagonists were developed based on training set of 49 compounds. The best four-feature pharmacophore model, includes two hydrophobic aromatic, one hydrophobic and one aromatic ring features, has the highest correlation coefficient (0.874), cost difference (368.677), low RMSD (2.876), as well as it shows a high goodness of fit and enrichment factor. Consequently, some hit compounds were introduced as final candidates by employing virtual screening and molecular docking procedure simultaneously. Among these compounds, six potential molecule were identified as potential virtual leads which, as such or upon further optimization, can be used to design novel P2X7R inhibitors.

  7. Astrocytes, but not neurons, exhibit constitutive activation of P2X7 receptors in mouse acute cortical slices under non-stimulated resting conditions.

    Science.gov (United States)

    Kamatsuka, Yosuke; Fukagawa, Manami; Furuta, Takahiro; Ohishi, Akihiro; Nishida, Kentaro; Nagasawa, Kazuki

    2014-01-01

    We previously demonstrated that the P2X7 receptor (P2X7R), a purinergic receptor, expressed by mouse cultured cortical astrocytes is constitutively activated without any exogenous stimulus, differing from the case of neurons. It is well known that astrocytic morphology differs between in vitro and in vivo situations, implying different functionalities. Brain acute slices are widely accepted as an in vitro experimental system that reflects in vivo cell conditions better than in vitro cell culture ones. We examined whether astrocytic P2X7Rs exhibited constitutive activation in mouse cortical slices. In acute cortical slices, P2X7R-immunoreactivity was detected in both glial fibrillary acidic protein-immunopositive astrocytes and microtubule-associated protein 2-immunopositive neurons. Astrocytic, but not neuronal, spontaneous uptake of propidium iodide, an indicator of P2X7R channel/pore activity, was inhibited by representative antagonists of P2X7R, but they had no effect on the uptake by astrocytes in membrane-permeabilized fixed slices. These findings indicate that astrocytes, but not neurons, in acute cortical slices exhibit constitutive activation of P2X7Rs under non-stimulated resting conditions as in the case of cell culture systems.

  8. Intra-Articular Blockade of P2X7 Receptor Reduces the Articular Hyperalgesia and Inflammation in the Knee Joint Synovitis Especially in Female Rats.

    Science.gov (United States)

    Teixeira, Juliana Maia; Dias, Elayne Vieira; Parada, Carlos Amílcar; Tambeli, Cláudia Herrera

    2017-02-01

    Synovitis is a key factor in joint disease pathophysiology, which affects a greater proportion of women than men. P2X7 receptor activation contributes to arthritis, but whether it plays a role in articular inflammatory pain in a sex-dependent manner is unknown. We investigated whether the P2X7 receptor blockade in the knee joint of male and female rats reduces the articular hyperalgesia and inflammation induced by a carrageenan knee joint synovitis model. Articular hyperalgesia was quantified using the rat knee joint incapacitation test and the knee joint inflammation, characterized by the concentration of cytokines tumor necrosis factor-α, interleukin-1β, interleukin-6, and cytokine-induced neutrophil chemoattractant-1, and by neutrophil migration, was quantified using enzyme-linked immunosorbent assay and by myeloperoxidase enzyme activity measurement, respectively. P2X7 receptor blockade by the articular coadministration of selective P2X7 receptor antagonist A740003 with carrageenan significantly reduced articular hyperalgesia, pro-inflammatory cytokine concentrations, and myeloperoxidase activity induced by carrageenan injection into the knee joint of male and estrus female rats. However, a lower dose of P2X7 receptor antagonist was sufficient to significantly induce the antihyperalgesic and anti-inflammatory effects in estrus female but not in male rats. These results suggest that P2X7 receptor activation by endogenous adenosine 5'-triphosphate is essential to articular hyperalgesia and inflammation development in the knee joint of male and female rats. However, female rats are more responsive than male rats to the antihyperalgesic and anti-inflammatory effects induced by P2X7 receptor blockade.

  9. Parameterization-based tracking for the P2 experiment

    Energy Technology Data Exchange (ETDEWEB)

    Sorokin, Iurii [Institut fuer Kernphysik and PRISMA Cluster of Excellence, Mainz (Germany); Collaboration: P2-Collaboration

    2016-07-01

    The P2 experiment at the new MESA accelerator in Mainz aims to determine the weak mixing angle by measuring the parity-violating asymmetry in elastic electron-proton scattering at low momentum transfer. To achieve an unprecedented precision an order of 10{sup 11} scattered electrons per second have to be acquired. %within the acceptance. Whereas the tracking system is not required to operate at such high rates, every attempt is made to achieve as high rate capability as possible. The P2 tracking system will consist of four planes of high-voltage monolithic active pixel sensors (HV-MAPS). With the present preliminary design one expects about 150 signal electron tracks and 20000 background hits (from bremsstrahlung photons) per plane in every 50 ns readout frame at the full rate. In order to cope with this extreme combinatorial background in on-line mode, a parameterization-based tracking is considered as a possible solution. The idea is to transform the hit positions into a set of weakly correlated quantities, and to find simple (e.g. polynomial) functions of these quantities, that would give the required characteristics of the track (e.g. momentum). The parameters of the functions are determined from a sample of high-quality tracks, taken either from a simulation, or reconstructed in a conventional way from a sample of low-rate data.

  10. Supporting Personal Semantic Annotations in P2P Semantic Wikis

    Science.gov (United States)

    Torres, Diego; Skaf-Molli, Hala; Díaz, Alicia; Molli, Pascal

    In this paper, we propose to extend Peer-to-Peer Semantic Wikis with personal semantic annotations. Semantic Wikis are one of the most successful Semantic Web applications. In semantic wikis, wikis pages are annotated with semantic data to facilitate the navigation, information retrieving and ontology emerging. Semantic data represents the shared knowledge base which describes the common understanding of the community. However, in a collaborative knowledge building process the knowledge is basically created by individuals who are involved in a social process. Therefore, it is fundamental to support personal knowledge building in a differentiated way. Currently there are no available semantic wikis that support both personal and shared understandings. In order to overcome this problem, we propose a P2P collaborative knowledge building process and extend semantic wikis with personal annotations facilities to express personal understanding. In this paper, we detail the personal semantic annotation model and show its implementation in P2P semantic wikis. We also detail an evaluation study which shows that personal annotations demand less cognitive efforts than semantic data and are very useful to enrich the shared knowledge base.

  11. Effects of a non-selective TRPC channel blocker, SKF-96365, on melittin-induced spontaneous persistent nociception and inflammatory pain hypersensitivity

    Institute of Scientific and Technical Information of China (English)

    Jing Ding; Jia-Rui Zhang; Yan Wang; Chun-Li Li; Dan Lu; Su-Min Guan; Jun Chen

    2012-01-01

    Objective Melittin is the main peptide in bee venom and causes both persistent spontaneous nociception and pain hypersensitivity.Our recent studies indicated that both transient receptor potential (TRP) vanilloid receptor 1 (TRPV1) and canonical TRPs (TRPCs) are involved in mediating the melittin-induced activation of different subpopulations of primary nociceptive cells.Here,we further determined whether TRPC channels are involved in melittin-induced inflammatory nociceptive responses in behavioral assays.Methods The anti-nociceptive and anti-hyperalgesic effects of localized peripheral administration of three doses of the non-selective TRPC antagonist,SKF-96365 (1-{β-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenyl}-1H-imidazole hydrochloride),were evaluated in melittin tests.Pain-related behaviors were rated by counting the number of paw flinches,and measuring paw withdrawal thermal latency (s) and paw withdrawl mechanical threshold (g),over a 1-h time-course.Results Localized peripheral SKF-96365 given before melittin prevented,and given after melittin significantly suppressed,the melittin-evoked persistent spontaneous nociception.Pre-blockade and post-suppression of activation of primary nociceptive activity resulted in decreased hypersensitivity to both thermal and mechanical stimuli applied to the primary injury site of the ipsilateral hindpaw,despite dose-effect differences between thermal and mechanical hyperalgesia.However,local administration of SKF-96365 into the contralateral hindpaw had no significant effect on any pain-associated behaviors.In addition,SKF-96365 had no effect on baseline threshold for either thermal or mechanical sensitivity under normal conditions.Conclusion Besides TRPV1,SKF-96365-sensitive TRPC channels might also be involved in the pathophysiological processing of melittin-induced inflammatory pain and hypersensitivity.Therapeutically,SKF-96365 is equally effective in preventing primary thermal and mechanical hyperalgesia as well as

  12. Dynamic increase in extracellular ATP accelerates photoreceptor cell apoptosis via ligation of P2RX7 in subretinal hemorrhage.

    Directory of Open Access Journals (Sweden)

    Shoji Notomi

    Full Text Available Photoreceptor degeneration is the most critical cause of visual impairment in age-related macular degeneration (AMD. In neovascular form of AMD, severe photoreceptor loss develops with subretinal hemorrhage due to choroidal neovascularization (CNV, growth of abnormal blood vessels from choroidal circulation. However, the detailed mechanisms of this process remain elusive. Here we demonstrate that neovascular AMD with subretinal hemorrhage accompanies a significant increase in extracellular ATP, and that extracellular ATP initiates neurodegenerative processes through specific ligation of Purinergic receptor P2X, ligand-gated ion channel, 7 (P2RX7; P2X7 receptor. Increased extracellular ATP levels were found in the vitreous samples of AMD patients with subretinal hemorrhage compared to control vitreous samples. Extravascular blood induced a massive release of ATP and photoreceptor cell apoptosis in co-culture with primary retinal cells. Photoreceptor cell apoptosis accompanied mitochondrial apoptotic pathways, namely activation of caspase-9 and translocation of apoptosis-inducing factor (AIF from mitochondria to nuclei, as well as TUNEL-detectable DNA fragmentation. These hallmarks of photoreceptor cell apoptosis were prevented by brilliant blue G (BBG, a selective P2RX7 antagonist, which is an approved adjuvant in ocular surgery. Finally, in a mouse model of subretinal hemorrhage, photoreceptor cells degenerated through BBG-inhibitable apoptosis, suggesting that ligation of P2RX7 by extracellular ATP may accelerate photoreceptor cell apoptosis in AMD with subretinal hemorrhage. Our results indicate a novel mechanism that could involve neuronal cell death not only in AMD but also in hemorrhagic disorders in the CNS and encourage the potential application of BBG as a neuroprotective therapy.

  13. Subcellular distribution and early signalling events of P2X7 receptors from mouse cerebellar granule neurons.

    Science.gov (United States)

    Sánchez-Nogueiro, Jesús; Marín-García, Patricia; Bustillo, Diego; Olivos-Oré, Luis Alcides; Miras-Portugal, María Teresa; Artalejo, Antonio R

    2014-12-05

    The subcellular distribution and early signalling events of P2X7 receptors were studied in mouse cerebellar granule neurons. Whole-cell patch-clamp recordings evidenced inwardly directed non-desensitizing currents following adenosine 5'-triphosphate (ATP; 600 µM) or 2'-3'-o-(4-benzoylbenzoyl)-adenosine 5'-triphosphate (BzATP; 100 µM) administration to cells bathed in a medium with no-added divalent cations (Ca(2+) and Mg(2+)). Nucleotide-activated currents were inhibited by superfusion of 2.5 mM Ca(2+), 1.2 mM Mg(2+) or 100 nM Brilliant Blue G (BBG), hence indicating the expression of ionotropic P2X7 receptors. Fura-2 calcium imaging showed [Ca(2+)]i elevations in response to ATP or BzATP at the somas and at a small number of axodendritic regions of granule neurons. Differential sensitivity of these [Ca(2+)]i increases to three different P2X7 receptor antagonists (100 nM BBG, 10 μM 4-[(2S)-2-[(5-isoquinolinylsulfonyl)methylamino]-3-oxo-3-(4-phenyl-1-piperazinyl)propyl] phenyl isoquinolinesulfonic acid ester, KN-62, and 1 μM 3-(5-(2,3-dichlorophenyl)-1H-tetrazol-1-yl)methyl pyridine hydrochloride hydrate, A-438079) revealed that P2X7 receptors are co-expressed with different P2Y receptors along the plasmalemma of granule neurons. Finally, experiments with the fluorescent dye YO-PRO-1 indicated that prolonged stimulation of P2X7 receptors does not lead to the opening of a membrane pore permeable to large cations. Altogether, our results emphasise the expression of functional P2X7 receptors at both the axodendritic and somatic levels in mouse cerebellar granule neurons, and favour the notion that P2X7 receptors might function in a subcellular localisation-specific manner: presynaptically, by controlling glutamate release, and on the cell somas, by supporting granule neuron survival against glutamate excytotoxicity.

  14. LncRNA NONRATT021972 involved the pathophysiologic processes mediated by P2X7 receptors in stellate ganglia after myocardial ischemic injury.

    Science.gov (United States)

    Zou, Lifang; Tu, Guihua; Xie, Wei; Wen, Shiyao; Xie, Qiuyu; Liu, Shuangmei; Li, Guilin; Gao, Yun; Xu, Hong; Wang, Shouyu; Xue, Yun; Wu, Bing; Lv, Qiulan; Ying, Mofeng; Zhang, Xi; Liang, Shangdong

    2016-03-01

    Adenosine triphosphate (ATP) acts on P2X receptors to initiate signal transmission. P2X7 receptors play a role in the pathophysiological process of myocardial ischemic injury. Long noncoding RNAs (lncRNAs) participate in numerous biological functions independent of protein translation. LncRNAs are implicated in nervous system diseases. This study investigated the effects of NONRATT021972 small interference RNA (siRNA) on the pathophysiologic processes mediated by P2X7 receptors in stellate ganglia (SG) after myocardial ischemic injury. Our results demonstrated that the expression of NONRATT021972 in SG was significantly higher in the myocardial ischemic (MI) group than in the control group. Treatment of MI rats with NONRATT021972 siRNA, the P2X7 antagonist brilliant blue G (BBG), or P2X7 siRNA improved the histology of injured ischemic cardiac tissues and decreased the elevated concentrations of serum myocardial enzymes, creatine kinase (CK), CK isoform MB (CK-MB), lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) compared to the MI rats. NONRATT021972 siRNA, BBG, or P2X7 siRNA treatment in MI rats decreased the expression levels of P2X7 immunoreactivity, P2X7 messenger RNA (mRNA), and P2X7 protein, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and phosphorylated p38 mitogen-activated protein kinase (p38 MAPK) in the SG compared to MI rats. NONRATT021972 siRNA treatment prevented the pathophysiologic processes mediated by P2X7 receptors in the SG after myocardial ischemic injury.

  15. Ondansetron, a selective 5-HT3 antagonist, antagonizes methamphetamine-induced anorexia in mice.

    Science.gov (United States)

    Ginawi, O T; Al-Majed, A A; Al-Suwailem, A K

    2005-03-01

    Effects of some selective serotonergic (5-HT) antagonists on methamphetamine-induced anorexia were investigated in male mice. The least possible dose of methamphetamine alone that caused significant anorectic activity was 11 micromolkg(-1), i.p. (2 mgkg(-1)). Various doses of some selective serotonergic receptor antagonists were administered half an hour before the above mentioned dose of methamphetamine. Methiothepin potentiated, whereas NAN-190, methysergide, mianserin and ondansetron antagonized methamphetamine-induced anorectic activity. The least possible doses of these antagonists which modified methamphetamine-induced anorexia were as follows: methiothepin (1.1 micromolkg(-1), i.p.), NAN-190 (4.2 micromolkg(-1), i.p.), methysergide (2.1 micromolkg(-1), i.p.), mianserin (3.3 micromolkg(-1), i.p.) and ondansetron (0.003 micromolkg(-1), i.p.). The serotonergic antagonists at the above mentioned doses did not modify the food intake of animals not treated with methamphetamine, except for methiothepin, which produced a significant reduction, and mianserin, which produced a significant increase in food intake. The results of the present study indicated that the anorectic activity induced by methamphetamine is related to the interactions of methamphetamine with 5-HT receptor. Since a very small dose (0.003 micromolkg(-1)) of ondansetron (the 5-HT(3) antagonist), as compared with the other antagonists used in this study, antagonized the anorexia induced by methamphetamine, the 5-HT(3) receptor is likely to be the site for this interaction.

  16. Capillary electrophoresis for the characterization of quantum dots after non-selective or selective bioconjugation with antibodies for immunoassay

    Directory of Open Access Journals (Sweden)

    Lai Edward PC

    2008-10-01

    Full Text Available Abstract Capillary electrophoresis coupled with laser-induced fluorescence was used for the characterization of quantum dots and their conjugates to biological molecules. The CE-LIF was laboratory-built and capable of injection (hydrodynamic and electrokinetic from sample volumes as low as 4 μL via the use of a modified micro-fluidic chip platform. Commercially available quantum dots were bioconjugated to proteins and immunoglobulins through the use of established techniques (non-selective and selective. Non-selective techniques involved the use of EDCHCl/sulfo-NHS for the conjugation of BSA and myoglobin to carboxylic acid-functionalized quantum dots. Selective techniques involved 1 the use of heterobifunctional crosslinker, sulfo-SMCC, for the conjugation of partially reduced IgG to amine-functionalized quantum dots, and 2 the conjugation of periodate-oxidized IgGs to hydrazide-functionalized quantum dots. The migration times of these conjugates were determined in comparison to their non-conjugated QD relatives based upon their charge-to-size ratio values. The performance of capillary electrophoresis in characterizing immunoconjugates of quantum dot-labeled IgGs was also evaluated. Together, both QDs and CE-LIF can be applied as a sensitive technique for the detection of biological molecules. This work will contribute to the advancements in applying nanotechnology for molecular diagnosis in medical field.

  17. Conductance simulation of the purinergic P2X2, P2X4, and P2X7 ionic channels using a combined Brownian dynamics and molecular dynamics approach.

    Science.gov (United States)

    Turchenkov, Dmitry A; Bystrov, Vladimir S

    2014-08-07

    This paper investigates the application of an original combined approach of molecular and Brownian dynamic methods with quantum chemistry calculations for modeling the process of conductance of ion channels using purinergic P2X family receptors P2X2, P2X4, and P2X7 as a case study. A simplified model of the ionic channel in the lipid bilayer has been developed. A high level of conductance (30 pS) of P2X2 ionic channel together with the key role of Asp349 in forming the selectivity filter of P2X2 has been shown by using this approach. Calculated P2X2 permeability to monovalent cations Li(+), Na(+), and K(+) conforms to the free diffusion coefficient of these ions, which shows the low selectivity of P2X2 ionic channel.

  18. Clinical experience in Europe with uroselective alpha1-antagonists.

    Science.gov (United States)

    Debruyne, F M; Van der Poel, H G

    1999-01-01

    alpha1-Adrenoreceptors are thought to be involved in prostate smooth muscle contractions and could hence play a role in the dynamic component of intravesical obstruction associated with symptomatic BPH. Consequently, since the mid-eighties alpha receptor blocking agents have been used for the treatment of BPH. Non-selective alpha blockers are usually associated with systemic side-effects which resulted in an exclusion or withdrawal of many patients from this form of treatment. With the availability of so-called uroselective alpha blockers the management picture has changed since it was anticipated that these compounds cause lesser side-effects with at least the same, or even better, efficacy. Comparative clinical studies are essential for determining the eventual advantages of the uroselective alpha1-antagonists and a large number of such studies have been performed worldwide studying the various available compounds. European studies with terazosin showed clear superiority of the drug over the placebo while causing only limited side-effects. Various other studies using alpha-blocking agents such as doxazosin, tamsulosin and alfuzosin yielded identical results. Especially with tamsulosin and alfuzosin, the side-effects were comparable with those encountered in the placebo group. About 7% of the patients using tamsulosin experienced retrograde ejaculation in one study which did not occur in the alfuzosin studies. Important studies in Europe have also investigated the value of a combination of an alpha blocker with a 5alpha-reductase inhibitor. Comparable studies in which both alfuzosin and doxazosin were combined with the 5alpha-reductase inhibitor Proscar have shown that a combination is not superior to a blocker monotherapy and especially in the ALFIN study the results show that alfuzosin monotherapy is superior to Proscar in the management of symptomatic BPH. European studies have evaluated Quality of Life, sexuality as well as socio-economical outcome of the

  19. Non-P2P network applicationautomatic feature recognition%非 P2P 网络应用自动化特征提取

    Institute of Scientific and Technical Information of China (English)

    丁斌; 焦素云; 闫晓亮

    2015-01-01

    在对流量进行分类的基础上,应用Apriori算法分析分类以后的非P2P流,能够更准确地分析出非P2 P的网络应用特征。%Based on the classified traffic flow between P2P and non‐P2P ,Apriori algorithm is used to analyzing the non‐P2P flow to get the high precise characteristics of non‐P2P network application .

  20. Activation of P2X7 receptors in glial satellite cells reduces pain through downregulation of P2X3 receptors in nociceptive neurons

    OpenAIRE

    Chen, Yong; Zhang, Xiaofei; Wang, Congying; Li, Guangwen; Gu, Yanping; Huang, Li-Yen Mae

    2008-01-01

    Purinergic ionotropic P2X7 receptors (P2X7Rs) are closely associated with excitotoxicity and nociception. Inhibition of P2X7R activation has been considered as a potentially useful strategy to improve recovery from spinal cord injury and reduce inflammatory damage to trauma. The physiological functions of P2X7Rs, however, are poorly understood, even though such information is essential for making the P2X7R an effective therapeutic target. We show here that P2X7Rs in satellite cells of dorsal ...

  1. Transmission to interneurons is via slow excitatory synaptic potentials mediated by P2Y(1 receptors during descending inhibition in guinea-pig ileum.

    Directory of Open Access Journals (Sweden)

    Peter D J Thornton

    Full Text Available BACKGROUND: The nature of synaptic transmission at functionally distinct synapses in intestinal reflex pathways has not been fully identified. In this study, we investigated whether transmission between interneurons in the descending inhibitory pathway is mediated by a purine acting at P2Y receptors to produce slow excitatory synaptic potentials (EPSPs. METHODOLOGY/PRINCIPAL FINDINGS: Myenteric neurons from guinea-pig ileum in vitro were impaled with intracellular microelectrodes. Responses to distension 15 mm oral to the recording site, in a separately perfused stimulation chamber and to electrical stimulation of local nerve trunks were recorded. A subset of neurons, previously identified as nitric oxide synthase immunoreactive descending interneurons, responded to both stimuli with slow EPSPs that were reversibly abolished by a high concentration of PPADS (30 μM, P2 receptor antagonist. When added to the central chamber of a three chambered organ bath, PPADS concentration-dependently depressed transmission through that chamber of descending inhibitory reflexes, measured as inhibitory junction potentials in the circular muscle of the anal chamber. Reflexes evoked by distension in the central chamber were unaffected. A similar depression of transmission was seen when the specific P2Y(1 receptor antagonist MRS 2179 (10 μM was in the central chamber. Blocking either nicotinic receptors (hexamethonium 200 μM or 5-HT(3 receptors (granisetron 1 μM together with P2 receptors had no greater effect than blocking P2 receptors alone. CONCLUSIONS/SIGNIFICANCE: Slow EPSPs mediated by P2Y(1 receptors, play a primary role in transmission between descending interneurons of the inhibitory reflexes in the guinea-pig ileum. This is the first demonstration for a primary role of excitatory metabotropic receptors in physiological transmission at a functionally identified synapse.

  2. Functional decreases in P2X7 receptors are associated with retinoic acid-induced neuronal differentiation of Neuro-2a neuroblastoma cells.

    Science.gov (United States)

    Wu, Pei-Yu; Lin, Yu-Chia; Chang, Chia-Ling; Lu, Hsing-Tsen; Chin, Chia-Hsuan; Hsu, Tsan-Ting; Chu, Dachen; Sun, Synthia H

    2009-06-01

    Neuro-2a (N2a) cells are derived from spontaneous neuroblastoma of mouse and capable to differentiate into neuronal-like cells. Recently, P2X7 receptor has been shown to sustain growth of human neuroblastoma cells but its role during neuronal differentiation remains unexamined.We characterized the role of P2X7 receptors in the retinoic acid (RA)-differentiated N2a cells. RA induced N2a cells differentiation into neurite bearing and neuronal specific proteins, microtubule-associated protein 2 (MAP2) and neuronal specific nuclear protein (NeuN), expressing neuronal-like cells. Interestingly, the RA-induced neuronal differentiation was associated with decreases in the expression and function of P2X7 receptors. Functional inhibition of P2X7 receptors by P2X7 receptor selective antagonists, 5'-triphosphate, periodate-oxidized 2',3'-dialdehyde ATP (oATP), brilliant blue G (BBG) or A438079 induced neurite outgrowth. In addition, RA and oATP treatment stimulated the expression of neuron-specific class III beta-tubulin (TuJ1), and knockdown of P2X7 receptor expression by siRNA induced neurite outgrowth. To elucidate the possible mechanism, we found the levels of basal intracellular Ca2+ concentrations ([Ca2+]i) were decreased in either RA- or oATP-differentiated or P2X7receptor knockdown N2a cells. Simply cultured N2a cells in low Ca2+ medium induced a 2-fold increase in neurite length. Treatment of N2a cells with ATP hydrolase apyrase and the P2X7 receptors selective antagonist oATP or BBG decreased cell viability and cell number. Nevertheless, oATP but not BBG decreased cell proliferation and cell cycle progression. These results suggest for the first time that decreases in expression/function of P2X7 receptors are involved in neuronal differentiation.We provide additional evidence shown that the ATP release-activated P2X7 receptor is important in maintaining cell survival of N2a neuroblastoma cells.

  3. Extracellular UDP and P2Y6 function as a danger signal to protect mice from vesicular stomatitis virus infection through an increase in IFN-β production.

    Science.gov (United States)

    Li, Ruimei; Tan, Binghe; Yan, Yan; Ma, Xiaobin; Zhang, Na; Zhang, Zhi; Liu, Mingyao; Qian, Min; Du, Bing

    2014-11-01

    Extracellular nucleotides that constitute a "danger signal" play an important role in the regulation of immune responses. However, the function and mechanism of extracellular UDP and P2Y6 in antiviral immunity remain unknown. In this study, we demonstrated the in vitro and in vivo protection of UDP/P2Y6 signaling in vesicular stomatitis virus (VSV) infection. First, we demonstrated that VSV-infected cells secrete UDP from the cytoplasm as a danger signal to arouse surrounding cells. Meanwhile, expression of the UDP-specific receptor P2Y6 also was enhanced by VSV. Consequently, UDP protects RAW 264.7 cells, murine embryonic fibroblasts, bone marrow-derived macrophages, and L929 cells from VSV and GFP lentivirus infection. This protection can be blocked by the P2Y6 selective antagonist MRS2578 or IFN-α/β receptor-blocking Ab. VSV-induced cell death and virus replication were both enhanced significantly by knocking down and knocking out P2Y6 in different cells. Mechanistically, UDP facilitates IFN-β secretion through the p38/JNK- and ATF-2/c-Jun-signaling pathways, which are crucial in promoting antiviral immunity. Interestingly, UDP was released through a caspase-cleaved pannexin-1 channel in VSV-induced apoptotic cells and protected cells from infection through P2Y6 receptor in an autocrine or paracrine manner. Furthermore, UDP also protected mice from VSV infection through P2Y6 receptors in an acute neurotropic infection mouse model. Taken together, these results demonstrate the important role of extracellular UDP and P2Y6 as a danger signal in antiviral immune responses and suggest a potential therapeutic role for UDP/P2Y6 in preventing and controlling viral diseases.

  4. Activation of the damage-associated molecular pattern receptor P2X7 induces interleukin-1β release from canine monocytes.

    Science.gov (United States)

    Jalilian, Iman; Peranec, Michelle; Curtis, Belinda L; Seavers, Aine; Spildrejorde, Mari; Sluyter, Vanessa; Sluyter, Ronald

    2012-09-15

    P2X7, a damage-associated molecular pattern receptor and adenosine 5'-triphosphate (ATP)-gated cation channel, plays an important role in the activation of the NALP3 inflammasome and subsequent release of interleukin (IL)-1β from human monocytes; however its role in monocytes from other species including the dog remains poorly defined. This study investigated the role of P2X7 in canine monocytes, including its role in IL-1β release. A fixed-time flow cytometric assay demonstrated that activation of P2X7 by extracellular ATP induces the uptake of the organic cation, YO-PRO-1(2+), into peripheral blood monocytes from various dog breeds, a process impaired by the specific P2X7 antagonist, A438079. Moreover, in five different breeds, relative P2X7 function in monocytes was about half that of peripheral blood T cells but similar to that of peripheral blood B cells. Reverse transcription-PCR demonstrated the presence of P2X7, NALP3, caspase-1 and IL-1β in LPS-primed canine monocytes. Immunoblotting confirmed the presence of P2X7 in LPS-primed canine monocytes. Finally, extracellular ATP induced YO-PRO-1(2+) uptake into and IL-1β release from these cells, with both processes impaired by A438079. These results demonstrate that P2X7 activation induces the uptake of organic cations into and the release of IL-1β from canine monocytes. These findings indicate that P2X7 may play an important role in IL-1β-dependent processes in dogs.

  5. New antagonist agents of neuropeptide y receptors

    Directory of Open Access Journals (Sweden)

    Ignacio Aldana

    2000-12-01

    Full Text Available In the CNS, NPY has been implicated in obesity and feeding, endocrine function and metabolism. Potent and selective rNPY antagonists will be able to probe the merits of this approach for the treatment of obesity. We report the synthesis and preliminary evaluation of some hydrazide derivatives as antagonists of rNPY.

  6. Electroacupuncture diminishes P2X2 and P2X3 purinergic receptor expression in dorsal root ganglia of rats with visceral hypersensitivity

    Institute of Scientific and Technical Information of China (English)

    Zhijun Weng; Luyi Wu; Yuan Lu; Lidong Wang; Linying Tan; Ming Dong; Yuhu Xin

    2013-01-01

    Electroacupuncture at Shangjuxu (ST37) and Tianshu (ST25) can improve visceral hypersensitivity in rats. Colorectal distension was used to establish a rat model of chronic visceral hypersensitivity. Immunohistochemistry was used to detect P2X2 and P2X3 receptor expression in dorsal root ganglia from rats with chronic visceral hypersensitivity. Results demonstrated that abdominal withdrawal reflex scores obviously increased following establishment of the model, indicating visceral hypersensitivity. Simultaneously, P2X2 and P2X3 receptor expression increased in dorsal root ganglia. After bilateral electroacupuncture at Shangjuxu and Tianshu, abdominal withdrawal reflex scores and P2X2 and P2X3 receptor expression decreased in rats with visceral hypersensitivity. These results indicated that electroacupuncture treatment improved visceral hypersensitivity in rats with irritable bowel syndrome by reducing P2X2 and P2X3 receptor expression in dorsal root ganglia.

  7. Effects of the non-selective phosphodiesterase inhibitor pentoxifylline on regional cerebral blood flow and large arteries in healthy subjects

    DEFF Research Database (Denmark)

    Kruuse, Christina; Jacobsen, T B; Thomsen, Lars Lykke

    2000-01-01

    -inhalation SPECT. High-frequency ultrasound was used for measurements of temporal and radial artery diameter. Cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) concentrations were assessed in plasma. Except for increased heart rate (P blood pressure (P ... or to other mechanisms is not clear. In the present double-blind crossover study, 10 healthy subjects received pentoxifylline 300 mg or placebo intravenously on separate days. Blood flow velocity in the middle cerebral artery (V(mca)) was recorded by transcranial Doppler and rCBF was measured using (133)Xenon......The vasodilating properties of the non-selective phosphodiesterase (PDE) inhibitor pentoxifylline were evaluated. Pentoxifylline has been reported to increase cerebral blood flow (CBF) and improve recovery rate of stroke patients. Whether these results are due to a dilating effect on arteries...

  8. P2P技术特点与网络安全%Characteristics and Network Security of P2P Technology

    Institute of Scientific and Technical Information of China (English)

    张尔谦

    2011-01-01

    This paper introduces the concept of P2P technology, technical characteristics and safety issues faced by P2P networks and to solve those problems.%本文介绍了P2P技术的概念、技术的特点以及P2P网络面临安全问题和解决这些问题的方案。

  9. An Effective Calculation of Reputation in P2P Networks

    Directory of Open Access Journals (Sweden)

    RVVSV Prasad

    2009-07-01

    Full Text Available With the advent of sophisticated networking technologies and the related applications, more and more computers are getting hooked to the Internet. This is mainly for utilizing several services ranging from information sharing to electronic transactions. P2P networks which allow decentralized systems, have posed problems related to trust when transactions have to be carried out. Current literature proposes several solutions for trust management and reputation computation. The solutions base their assessment of reputations on the number of successful transactions or on the similarity of the feedbacks. There are some concerns in the feedback ratings if we are not considering the issues like number of transactions, frequency of transactions with the same peer and different peers, age of transaction, how frequently a given peer attends a common vendor, and the number of common vendors between the pairs. This paper puts forward a reputation computation system addressing these concerns. It implicitly allows detection of malicious peers. It also incorporates a corrective mechanism, if the feedbacks are from more number of malicious peers. The implementations and the results that support our claims are also presented.

  10. Survey on Distributed Data Mining in P2P Networks

    CERN Document Server

    T, Rekha Sunny

    2012-01-01

    The exponential increase of availability of digital data and the necessity to process it in business and scientific fields has literally forced upon us the need to analyze and mine useful knowledge from it. Traditionally data mining has used a data warehousing model of gathering all data into a central site, and then running an algorithm upon that data. Such a centralized approach is fundamentally inappropriate due to many reasons like huge amount of data, infeasibility to centralize data stored at multiple sites, bandwidth limitation and privacy concerns. To solve these problems, Distributed Data Mining (DDM) has emerged as a hot research area. Careful attention in the usage of distributed resources of data, computing, communication, and human factors in a near optimal fashion are paid by distributed data mining. DDM is gaining attention in peer-to-peer (P2P) systems which are emerging as a choice of solution for applications such as file sharing, collaborative movie and song scoring, electronic commerce, an...

  11. Improved Degree Search Algorithms in Unstructured P2P Networks

    Directory of Open Access Journals (Sweden)

    Guole Liu

    2012-01-01

    Full Text Available Searching and retrieving the demanded correct information is one important problem in networks; especially, designing an efficient search algorithm is a key challenge in unstructured peer-to-peer (P2P networks. Breadth-first search (BFS and depth-first search (DFS are the current two typical search methods. BFS-based algorithms show the perfect performance in the aspect of search success rate of network resources, while bringing the huge search messages. On the contrary, DFS-based algorithms reduce the search message quantity and also cause the dropping of search success ratio. To address the problem that only one of performances is excellent, we propose two memory function degree search algorithms: memory function maximum degree algorithm (MD and memory function preference degree algorithm (PD. We study their performance including the search success rate and the search message quantity in different networks, which are scale-free networks, random graph networks, and small-world networks. Simulations show that the two performances are both excellent at the same time, and the performances are improved at least 10 times.

  12. P2P模型在校园网上的应用研究%Study on application of P2P network model in campus network

    Institute of Scientific and Technical Information of China (English)

    王晓燕; 张伟

    2012-01-01

    针对目前流行的P2P网络模型的特点,结合非结构化的P2P网络Gnutella路由和结构化的P2P Pastry路由,提出了一种应用在校园网内的P2P结构模型方案,并给出了详细的P2P节点结构和路由,同时提出了设计该网络模型上的P2P网络应用软件的可行性.%This article in view of the present popular P2P network model characteristics,combined with unstructured P2P network Gnutella routing and structured P2P Pastry routing,puts forward a kind of application in campus network of P2P structure model,and gives the detailed P2P node structure and routing,and puts forward the design of the network model of the P2P network application software feasibility.

  13. Peripheral nerve P2 basic protein and the Guillain-Barre syndrome : In vitro demonstration of P2-specific antibody-secreting cells

    NARCIS (Netherlands)

    Luijten, J.A.F.M.; Jong, W.A.C. de; Demel, R.A.; Heijnen, C.J.; Ballieux, R.E.

    1984-01-01

    An immune response to the peripheral nerve basic protein P2 may be operative in the pathogenesis of the Guillain-Barré syndrome (GBS). A method is described for the purification of P2 of human origin. Purified P2 was used to investigate whether lymphocytes derived from peripheral blood of GBS

  14. Peripheral nerve P2 basic protein and the Guillain-Barre syndrome : In vitro demonstration of P2-specific antibody-secreting cells

    NARCIS (Netherlands)

    Luijten, J.A.F.M.; Jong, W.A.C. de; Demel, R.A.; Heijnen, C.J.; Ballieux, R.E.

    1984-01-01

    An immune response to the peripheral nerve basic protein P2 may be operative in the pathogenesis of the Guillain-Barré syndrome (GBS). A method is described for the purification of P2 of human origin. Purified P2 was used to investigate whether lymphocytes derived from peripheral blood of GBS patien

  15. Increase in cardiac P2X1-and P2Y2-receptor mRNA levels in congestive heart failure

    DEFF Research Database (Denmark)

    Hou, M; Malmsjö, M; Möller, S;

    1999-01-01

    We wanted to study the expression of P2-receptors at the mRNA-level in the heart and if it is affected by congestive heart failure (CHF). To quantify the P2 receptor mRNA-expression we used a competitive RT-PCR protocol which is based on an internal RNA standard. The P2 receptor m...

  16. Peripheral nerve P2 basic protein and the Guillain-Barre syndrome : In vitro demonstration of P2-specific antibody-secreting cells

    NARCIS (Netherlands)

    Luijten, J.A.F.M.; Jong, W.A.C. de; Demel, R.A.; Heijnen, C.J.; Ballieux, R.E.

    1984-01-01

    An immune response to the peripheral nerve basic protein P2 may be operative in the pathogenesis of the Guillain-Barré syndrome (GBS). A method is described for the purification of P2 of human origin. Purified P2 was used to investigate whether lymphocytes derived from peripheral blood of GBS patien

  17. Activation of purinergic receptors (P2) in the renal medulla promotes endothelin-dependent natriuresis in male rats.

    Science.gov (United States)

    Gohar, Eman Y; Speed, Joshua S; Kasztan, Malgorzata; Jin, Chunhua; Pollock, David M

    2016-08-01

    Renal endothelin-1 (ET-1) and purinergic signaling systems regulate Na(+) reabsorption in the renal medulla. A link between the renal ET-1 and purinergic systems was demonstrated in vitro, however, the in vivo interaction between these systems has not been defined. To test whether renal medullary activation of purinergic (P2) receptors promotes ET-dependent natriuresis, we determined the effect of increased medullary NaCl loading on Na(+) excretion and inner medullary ET-1 mRNA expression in anesthetized adult male Sprague-Dawley rats in the presence and absence of purinergic receptor antagonism. Isosmotic saline (NaCl; 284 mosmol/kgH2O) was infused into the medullary interstitium (500 μl/h) during a 30-min baseline urine collection period, followed by isosmotic or hyperosmotic saline (1,800 mosmol/kgH2O) for two further 30-min urine collection periods. Na(+) excretion was significantly increased during intramedullary infusion of hyperosmotic saline. Compared with isosmotic saline, hyperosmotic saline infused into the renal medulla caused significant increases in inner medullary ET-1 mRNA expression. Renal intramedullary infusion of the P2 receptor antagonist suramin inhibited the increase in Na(+) excretion and inner medullary ET-1 mRNA expression induced by NaCl loading in the renal medulla. Activation of medullary P2Y2/4 receptors by infusion of UTP increased urinary Na(+) excretion. Combined ETA and ETB receptor blockade abolished the natriuretic response to intramedullary infusion of UTP. These data demonstrate that activation of medullary P2 receptors promotes ET-dependent natriuresis in male rats, suggesting that the renal ET-1 and purinergic signaling systems interact to efficiently facilitate excretion of a NaCl load.

  18. Pannexin channels mediate the acquisition of myogenic commitment in C2C12 reserve cells promoted by P2 receptor activation

    Science.gov (United States)

    Riquelme, Manuel A.; Cea, Luis A.; Vega, José L.; Puebla, Carlos; Vargas, Aníbal A.; Shoji, Kenji F.; Subiabre, Mario; Sáez, Juan C.

    2015-01-01

    The acquisition of myoblast commitment to the myogenic linage requires rises in intracellular free Ca2+ concentration ([Ca2+]i). Putative cell membrane pathways involved in these [Ca2+]i increments are P2 receptors (P2Rs) as well as connexin (Cx) and/or pannexin (Panx) hemichannels and channels (Cx HChs and Panx Chs), respectively, which are known to permeate Ca2+. Reserve cells (RCs) are uncommitted myoblasts obtained from differentiated C2C12 cell cultures, which acquire commitment upon replating. Regarding these cells, we found that extracellular ATP increases the [Ca2+]i via P2Rs. Moreover, ATP increases the plasma membrane permeability to small molecules and a non-selective membrane current, both of which were inhibited by Cx HCh/Panx1Ch blockers. However, RCs exposed to divalent cation-free saline solution, which is known to activate Cx HChs (but not Panx Chs), did not enhance membrane permeability, thus ruling out the possible involvement of Cx HChs. Moreover, ATP-induced membrane permeability was inhibited with blockers of P2Rs that activate Panx Chs. In addition, exogenous ATP induced the expression of myogenic commitment and increased MyoD levels, which was prevented by the inhibition of P2Rs or knockdown of Panx1 Chs. Similarly, increases in MyoD levels induced by ATP released by RCs were inhibited by Panx Ch/Cx HCh blockers. Myogenic commitment acquisition thus requires a feed-forward mechanism mediated by extracellular ATP, P2Rs, and Panx Chs. PMID:26000275

  19. Pannexin Channels Mediate the Acquisition of Myogenic Commitment in C2C12 Reserve Cells Promoted by P2 Receptor Activation

    Directory of Open Access Journals (Sweden)

    Manuel Antonio Riquelme

    2015-05-01

    Full Text Available The acquisition of myoblast commitment to the myogenic linage requires rises in intracellular free Ca2+ concentration ([Ca2+]i. Putative cell membrane pathways involved in these [Ca2+]i increments are P2 receptors (P2Rs as well as connexin (Cx and/or pannexin (Panx hemichannels and channels (Cx HChs and Panx Chs, respectively, which are known to permeate Ca2+. Reserve cells (RCs are uncommitted myoblasts obtained from differentiated C2C12 cell cultures, which acquire commitment upon replating. Regarding these cells, we found that extracellular ATP increases the [Ca2+]i via P2Rs. Moreover, ATP increases the plasma membrane permeability to small molecules and a non-selective membrane current, both of which were inhibited by Cx HCh/Panx1Ch blockers. However, RCs exposed to divalent cation-free saline solution, which is known to activate Cx HChs (but not Panx Chs, did not enhance membrane permeability, thus ruling out the possible involvement of Cx HChs. Moreover, ATP-induced membrane permeability was inhibited with blockers of P2Rs that activate Panx Chs. In addition, exogenous ATP induced the expression of myogenic commitment and increased MyoD levels, which was prevented by the inhibition of P2Rs or knockdown of Panx1 Chs. Similarly, increases in MyoD levels induced by ATP released by RCs were inhibited by Panx Ch/Cx HCh blockers. Myogenic commitment acquisition thus requires a feed-forward mechanism mediated by extracellular ATP, P2Rs and Panx Chs.

  20. 英美P2P监管体系比较与我国P2P监管思路研究

    Institute of Scientific and Technical Information of China (English)

    黄震; 邓建鹏; 熊明; 任一奇; 乔宇涵

    2014-01-01

    随着我国P2P行业的快速发展和风险问题的不断暴露,P2P监管也受到各界高度重视。英美两国的P2P监管体系相对完善,对我国P2P监管具有重要的借鉴意义。本文比较了英美两国P2P的监管法规和监管架构,分析了其对我国P2P监管的启示。研究发现,英国的P2P监管采取监管立法与行业自律相结合,美国以SEC为核心监管机构,多部门分类监管。在此基础上,本文结合我国国情和P2P行业发展现状,提出了当前我国P2P监管的思路:划出监管红线,鼓励创新为主;可重点参照英国实践,行业自律与国家立法相互补充,逐步完善我国P2P监管的法律规范;明确监管机构和重点,完善P2P平台退出机制。%With the rapid development of the P2P industry and the disclosures of its risk, the regulations of P2P are of high concerns. The P2P regulatory systems in USA and UK are more advanced therefore are helpful in developing China's P2P regulatory system. This paper compares the P2P regulatory systems in USA and UK and explores lessons that can be drawn for China's P2P regulatory system. We find that UK combines legislative supervisions with self-regulations as its P2P regulatory system, while in USA the SEC supervisions are the core. Based on the comparisons, China's reality and the current status of China's P2P industry, we propose some suggestions for China's P2P regulations including setting a regulatory boundary as the red line, encouraging creative activities, completing China's regulatory laws on P2P with reference to UK, identifying the main regulatory institutions and their focuses.

  1. Double P2X2/P2X3 Purinergic Receptor Knockout Mice Do Not Taste NaCl or the Artificial Sweetener SC45647

    Science.gov (United States)

    Eddy, Meghan C.; Eschle, Benjamin K.; Barrows, Jennell; Hallock, Robert M.; Finger, Thomas E.

    2009-01-01

    The P2X ionotropic purinergic receptors, P2X2 and P2X3, are essential for transmission of taste information from taste buds to the gustatory nerves. Mice lacking both P2X2 and P2X3 purinergic receptors (P2X2/P2X3Dbl−/−) exhibit no taste-evoked activity in the chorda tympani and glossopharyngeal nerves when stimulated with taste stimuli from any of the 5 classical taste quality groups (salt, sweet, sour, bitter, and umami) nor do the mice show taste preferences for sweet or umami, or avoidance of bitter substances (Finger et al. 2005. ATP signaling is crucial for communication from taste buds to gustatory nerves. Science. 310[5753]:1495–1499). Here, we compare the ability of P2X2/P2X3Dbl−/− mice and P2X2/P2X3Dbl+/+ wild-type (WT) mice to detect NaCl in brief-access tests and conditioned aversion paradigms. Brief-access testing with NaCl revealed that whereas WT mice decrease licking at 300 mM and above, the P2X2/P2X3Dbl−/− mice do not show any change in lick rates. In conditioned aversion tests, P2X2/P2X3Dbl−/− mice did not develop a learned aversion to NaCl or the artificial sweetener SC45647, both of which are easily avoided by conditioned WT mice. The inability of P2X2/P2X3Dbl−/− mice to show avoidance of these taste stimuli was not due to an inability to learn the task because both WT and P2X2/P2X3Dbl−/− mice learned to avoid a combination of SC45647 and amyl acetate (an odor cue). These data suggest that P2X2/P2X3Dbl−/− mice are unable to respond to NaCl or SC45647 as taste stimuli, mirroring the lack of gustatory nerve responses to these substances. PMID:19833661

  2. Characterization of (11)C-GSK1482160 for Targeting the P2X7 Receptor as a Biomarker for Neuroinflammation.

    Science.gov (United States)

    Territo, Paul R; Meyer, Jill A; Peters, Jonathan S; Riley, Amanda A; McCarthy, Brian P; Gao, Mingzhang; Wang, Min; Green, Mark A; Zheng, Qi-Huang; Hutchins, Gary D

    2017-03-01

    The purinergic receptor subtype 7 (P2X7R) represents a novel molecular target for imaging neuroinflammation via PET. GSK1482160, a potent P2X7R antagonist, has high receptor affinity, high blood-brain barrier penetration, and the ability to be radiolabeled with (11)C. We report the initial physical and biologic characterization of this novel ligand. Methods:(11)C-GSK1482160 was synthesized according to published methods. Cell density studies were performed on human embryonic kidney cell lines expressing human P2X7R (HEK293-hP2X7R) and underwent Western blotting, an immunofluorescence assay, and radioimmunohistochemistry analysis using P2X7R polyclonal antibodies. Receptor density and binding potential were determined by saturation and association-disassociation kinetics, respectively. Peak immune response to lipopolysaccharide treatment in mice was determined in time course studies and analyzed via Iba1 and P2X7R Western blotting and Iba1 immunohistochemistry. Whole-animal biodistribution studies were performed on saline- or lipopolysaccharide-treated mice at 15, 30, and 60 min after radiotracer administration. Dynamic in vivo PET/CT was performed on the mice at 72 h after administration of saline, lipopolysaccharide, or lipopolysaccharide + blocking, and 2-compartment, 5-parameter tracer kinetic modeling of brain regions was performed. Results: P2X7R changed linearly with concentrations or cell numbers. For high-specific-activity (11)C-GSK1482160, receptor density and Kd were 1.15 ± 0.12 nM and 3.03 ± 0.10 pmol/mg, respectively, in HEK293-hP2X7R membranes. Association constant kon, dissociation constant koff, and binding potential (kon/koff) in HEK293-hP2X7R cells were 0.2312 ± 0.01542 min(-1)⋅nM(-1), 0.2547 ± 0.0155 min(-1), and 1.0277 ± 0.207, respectively. Whole-brain Iba1 expression in lipopolysaccharide-treated mice peaked by 72 h on immunohistochemistry, and Western blot analysis of P2X7R for saline- and lipopolysaccharide-treated brain sections

  3. Lack of neuroprotection in the absence of P2X7 receptors in toxin-induced animal models of Parkinson's disease

    Directory of Open Access Journals (Sweden)

    Kittel Ágnes

    2011-05-01

    Full Text Available Abstract Background Previous studies indicate a role of P2X7 receptors in processes that lead to neuronal death. The main objective of our study was to examine whether genetic deletion or pharmacological blockade of P2X7 receptors influenced dopaminergic cell death in various models of Parkinson's disease (PD. Results mRNA encoding P2X7 and P2X4 receptors was up-regulated after treatment of PC12 cells with 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP. P2X7 antagonists protected against MPTP and rotenone induced toxicity in the LDH assay, but failed to protect after rotenone treatment in the MTT assay in PC12 cells and in primary midbrain culture. In vivo MPTP and in vitro rotenone pretreatments increased the mRNA expression of P2X7 receptors in the striatum and substantia nigra of wild-type mice. Basal mRNA expression of P2X4 receptors was higher in P2X7 knockout mice and was further up-regulated by MPTP treatment. Genetic deletion or pharmacological inhibition of P2X7 receptors did not change survival rate or depletion of striatal endogenous dopamine (DA content after in vivo MPTP or in vitro rotenone treatment. However, depletion of norepinephrine was significant after MPTP treatment only in P2X7 knockout mice. The basal ATP content was higher in the substantia nigra of wild-type mice, but the ADP level was lower. Rotenone treatment elicited a similar reduction in ATP content in the substantia nigra of both genotypes, whereas reduction of ATP was more pronounced after rotenone treatment in striatal slices of P2X7 deficient mice. Although the endogenous amino acid content remained unchanged, the level of the endocannabinoid, 2-AG, was elevated by rotenone in the striatum of wild-type mice, an effect that was absent in mice deficient in P2X7 receptors. Conclusions We conclude that P2X7 receptor deficiency or inhibition does not support the survival of dopaminergic neurons in an in vivo or in vitro models of PD.

  4. P2 receptors in human heart: upregulation of P2X6 in patients undergoing heart transplantation, interaction with TNFalpha and potential role in myocardial cell death.

    Science.gov (United States)

    Banfi, Cristina; Ferrario, Silvia; De Vincenti, Ombretta; Ceruti, Stefania; Fumagalli, Marta; Mazzola, Alessia; D' Ambrosi, Nadia; Volontè, Cinzia; Fratto, Pasquale; Vitali, Ettore; Burnstock, Geoffrey; Beltrami, Elena; Parolari, Alessandro; Polvani, GianLuca; Biglioli, Paolo; Tremoli, Elena; Abbracchio, Maria P

    2005-12-01

    ATP acts as a neurotransmitter via seven P2X receptor-channels for Na(+) and Ca(2+), and eight G-protein-coupled P2Y receptors. Despite evidence suggesting roles in human heart, the map of myocardial P2 receptors is incomplete, and their involvement in chronic heart failure (CHF) has never received adequate attention. In left myocardia from five to nine control and 5-12 CHF subjects undergoing heart transplantation, we analyzed the full repertoire of P2 receptors and of 10 "orphan" P2Y-like receptors. All known P2Y receptors (i.e. P2Y(1,2,4,6,11,12,13,14)) and two P2Y-like receptors (GPR91 and GPR17) were detected in all subjects. All known P2X(1-7) receptors were also detected; of these, only P2X(6) was upregulated in CHF, as confirmed by quantitative real time-PCR. The potential significance of this change was studied in primary cardiac fibroblasts freshly isolated from young pigs. Exposure of cardiac fibroblasts to ATP or its hydrolysis-resistant-analog benzoylATP induced apoptosis. TNFalpha (a cytokine implicated in CHF progression) exacerbated cell death. Similar effects were induced by ATP and TNFalpha in a murine cardiomyocytic cell line. In cardiac fibroblasts, TNFalpha inhibited the downregulation of P2X(6) mRNA associated to prolonged agonist exposure, suggesting that, by preventing ATP-induced P2X(6) desensitization, TNFalpha may abolish a defense mechanism meant at avoiding Ca(2+) overload and, ultimately, Ca(2+)-dependent cell death. This may provide a basis for P2X(6) upregulation in CHF. In conclusion, we provide the first characterization of P2 receptors in the human heart and suggest that the interaction between TNFalpha and the upregulated P2X(6) receptor may represent a novel pathogenic mechanism in CHF.

  5. Ca(2+) induces PI(4,5)P2 clusters on lipid bilayers at physiological PI(4,5)P2 and Ca(2+) concentrations.

    Science.gov (United States)

    Sarmento, Maria J; Coutinho, Ana; Fedorov, Aleksander; Prieto, Manuel; Fernandes, Fabio

    2014-03-01

    Calcium has been shown to induce clustering of PI(4,5)P2 at high and non-physiological concentrations of both the divalent ion and the phosphatidylinositol, or on supported lipid monolayers. In lipid bilayers at physiological conditions, clusters are not detected through microscopic techniques. Here, we aimed to determine through spectroscopic methodologies if calcium plays a role in PI(4,5)P2 lateral distribution on lipid bilayers under physiological conditions. Using several different approaches which included information on fluorescence quantum yield, polarization, spectra and diffusion properties of a fluorescent derivative of PI(4,5)P2 (TopFluor(TF)-PI(4,5)P2), we show that Ca(2+) promotes PI(4,5)P2 clustering in lipid bilayers at physiological concentrations of both Ca(2+) and PI(4,5)P2. Fluorescence depolarization data of TF-PI(4,5)P2 in the presence of calcium suggests that under physiological concentrations of PI(4,5)P2 and calcium, the average cluster size comprises ~15 PI(4,5)P2 molecules. The presence of Ca(2+)-induced PI(4,5)P2 clusters is supported by FCS data. Additionally, calcium mediated PI(4,5)P2 clustering was more pronounced in liquid ordered (lo) membranes, and the PI(4,5)P2-Ca(2+) clusters presented an increased affinity for lo domains. In this way, PI(4,5)P2 could function as a lipid calcium sensor and the increased efficiency of calcium-mediated PI(4,5)P2 clustering on lo domains might provide targeted nucleation sites for PI(4,5)P2 clusters upon calcium stimulus.

  6. Peer behavior based proactive P2P worm detection%基于节点行为的主动 P2P 蠕虫检测

    Institute of Scientific and Technical Information of China (English)

    朱晖; 李伟华; 史豪斌

    2013-01-01

    Proactive P2P worm propagation is a serious security threat to P2P network and Internet. By researching the peer be-havior of propagating proactive P2P worm, this paper puts forward PBD(Peer Behavior based Detection)to detect proactive P2P worm. On this basis, it designs and implements a PPWDS(Proactive P2P Worm Detection System). This system adopts CUSUM algorithm to carry out real time monitoring to the outbound short link of P2P peers. Experiments show that PBD is an effective method of proactive P2P worm detect.%  主动 P2P 蠕虫的传播会对 P2P 网络以及互联网的安全造成严重威胁。通过研究主动 P2P 蠕虫传播时节点行为,提出一种基于节点行为的主动 P2P 蠕虫检测方法 PBD(Peer Behavior based Detection)。在此基础上设计和实现了一个主动 P2P 蠕虫检测系统 PPWDS(Proactive P2P Worm Detection System),该系统采用 CUSUM 算法对 P2P 节点出站短连接进行实时监控。实验表明,PBD 是检测主动 P2P 蠕虫的一种有效方法。

  7. Inhibition of P2X7 receptor ameliorates transient global cerebral ischemia/reperfusion injury via modulating inflammatory responses in the rat hippocampus

    Directory of Open Access Journals (Sweden)

    Chu Ketan

    2012-04-01

    Full Text Available Abstract Background Neuroinflammation plays an important role in cerebral ischemia/reperfusion (I/R injury. The P2X7 receptor (P2X7R has been reported to be involved in the inflammatory response of many central nervous system diseases. However, the role of P2X7Rs in transient global cerebral I/R injury remains unclear. The purpose of this study is to determine the effects of inhibiting the P2X7R in a rat model of transient global cerebral I/R injury, and then to explore the association between the P2X7R and neuroinflammation after transient global cerebral I/R injury. Methods Immediately after infusion with the P2X7R antagonists Brilliant blue G (BBG, adenosine 5′-triphosphate-2′,3′-dialdehyde (OxATP or A-438079, 20 minutes of transient global cerebral I/R was induced using the four-vessel occlusion (4-VO method in rats. Survival rate was calculated, neuronal death in the hippocampal CA1 region was observed using H & E staining, and DNA cleavage was observed by deoxynucleotidyl transferase-mediated UTP nick end labeling TUNEL. In addition, behavioral deficits were measured using the Morris water maze, and RT-PCR and immunohistochemical staining were performed to measure the expression of IL-1β, TNF-α and IL-6, and to identify activated microglia and astrocytes. Results The P2X7R antagonists protected against transient global cerebral I/R injury in a dosage-dependent manner. A high dosage of BBG (10 μg and A-0438079 (3 μg, and a low dosage of OxATP (1 μg significantly increased survival rates, reduced I/R-induced learning memory deficit, and reduced I/R-induced neuronal death, DNA cleavage, and glial activation and inflammatory cytokine overexpression in the hippocampus. Conclusions Our study indicates that inhibiting P2X7Rs protects against transient global cerebral I/R injury by reducing the I/R-induced inflammatory response, which suggests inhibition of P2X7Rs may be a promising therapeutic strategy for clinical treatment of

  8. The mouse defense test battery: evaluation of the effects of non-selective and BZ-1 (omega1) selective, benzodiazepine receptor ligands.

    Science.gov (United States)

    Griebel, G.; Sanger, D.J.; Perrault, G.

    1996-11-01

    The behavioral effects of several benzodiazepine (BZ) (omega) receptor ligands were compared using the Mouse Defense Test Battery which has been designed to assess defensive reactions of Swiss mice confronted with a natural threat (a rat) and situations associated with this threat. Primary measures taken before, during and after rat confrontation were escape attempts, flight, risk assessment and defensive threat and attack. The drugs used included non-selective BZ (omega) full (clonazepam, clorazepate, chlordiazepoxide and diazepam) and partial (bretazenil and imidazenil) agonists, and BZ-1 (omega1) selective (abecarnil, CL 218,872 and zolpidem) receptor ligands. With the exception of clonazepam, non-selective BZ (omega) receptor compounds only partially affected flight behaviors. The drugs reduced some but not all flight measures in response to the approaching rat, whereas clonazepam attenuated all flight reactions. In contrast to their mild and inconsistent actions on flight, the non-selective BZ (omega) receptor agonists displayed clear effects on risk assessment when subjects were chased by the rat. When contact was forced between the subject and the rat, the non-selective BZ (omega) receptor full agonists reduced defensive threat and attack reactions, while the partial agonists imidazenil and bretazenil only weakly attenuated defensive attack behavior. Similarly, after the rat had been removed from the test area, the non-selective BZ (omega) receptor full agonists displayed greater efficacy than the partial agonists in reducing escape attempts. Overall, results obtained with the selective BZ-1 (omega1) receptor ligands demonstrated either no clear effects or no specific action on defensive reactions. Taken together, these data demonstrate that: (1) non-selective BZ (omega) agonists displaying high intrinsic activity affect a wider range of defensive behaviors than non-selective BZ (omega) receptor partial agonists; (2) the defense system does not involve

  9. Early Recovery of Salmonella from Food Using a 6-Hour Non-selective Pre-enrichment and Reformulation of Tetrathionate Broth

    Science.gov (United States)

    Daquigan, Ninalynn; Grim, Christopher J.; White, James R.; Hanes, Darcy E.; Jarvis, Karen G.

    2016-01-01

    Culture based methods are commonly employed to detect pathogens in food and environmental samples. These methods are time consuming and complex, requiring multiple non-selective and selective enrichment broths, and usually take at least 1 week to recover and identify pathogens. Improving pathogen detection in foods is a primary goal for regulatory agencies and industry. Salmonella detection in food relies on a series of culture steps in broth formulations optimized to resuscitate Salmonella and reduce the abundance of competitive bacteria. Examples of non-selective pre-enrichment broths used to isolate Salmonella from food include Lactose, Universal Pre-enrichment, BPW, and Trypticase Soy broths. Tetrathionate (TT) and Rappaport–Vassiliadis (RV) broths are employed after a 24-h non-selective enrichment to select for Salmonella and hamper the growth of competitive bacteria. In this study, we tested a new formulation of TT broth that lacks brilliant green dye and has lower levels of TT . We employed this TT broth formulation in conjunction with a 6-h non-selective pre-enrichment period and determined that Salmonella recovery was possible one day earlier than standard food culture methods. We tested the shortened culture method in different non-selective enrichment broths, enumerated Salmonella in the non-selective enrichments, and used 16S rRNA gene sequencing to determine the proportional abundances of Salmonella in the TT and RV selective enrichments. Together these data revealed that a 6-h non-selective pre-enrichment reduces the levels of competitive bacteria inoculated into the selective TT and RV broths, enabling the recovery of Salmonella 1 day earlier than standard culture enrichment methods. PMID:28082968

  10. P2P and its Application in Enterprise Computing%P2P及其在企业计算中的应用

    Institute of Scientific and Technical Information of China (English)

    彭舰; 杨思忠; 刘锦德

    2003-01-01

    Owing to the popularity of Napster and Guntella, the concept of P2P (Peer-to-Peer)is highlighted again.P2P is a mindset and the rethinking of the traditional network computing based on the client/server model. P2Pmeans to decentralize some aspects of a system, in order for the entities to exchange directly, which will explore theresources at the edge of network. The implication of P2P is expounded, and some typical P2P systems are listed.This paper also details the taxonomy of the architecture of P2P computing. Then, we delve into the application ofP2P in enterprise computing.

  11. A Truncated P2X7 Receptor Variant (P2X7-j) Endogenously Expressed in Cervical Cancer Cells Antagonizes the Full-length P2X7 Receptor through Hetero-oligomerization*

    OpenAIRE

    Feng, Ying-Hong; LI Xin; Wang, Liqin; Zhou, Lingying; Gorodeski, George I.

    2006-01-01

    A truncated naturally occurring variant of the human receptor P2X7 was identified in cancer cervical cells. The novel protein (P2X7-j), a polypeptide of 258 amino acids, lacks the entire intracellular carboxyl terminus, the second transmembrane domain, and the distal third of the extracellular loop of the full-length P2X7 receptor. The P2X7-j was expressed in the plasma membrane; it showed diminished ligand-binding and channel function capacities and failed to form pores and mediate apoptosis...

  12. Analysis on Optimization of P2P Network Group Algorithms%试析P2P网络群发通信算法的优化

    Institute of Scientific and Technical Information of China (English)

    苏航

    2013-01-01

      在当前的计算机网络运行环境中,P2P(Peer-to-Peer)是互联网整体构架的基础。这里介绍了P2P网络的运行环境和在网络运行环境中P2P技术的应用,基于当前P2P网络的应用与发展,分析了P2P网络群发通信机制的特点,提出了P2P网络群发通信算法优化的方式,以更好地达到关于P2P网络群发通信算法优化的目标,同时,需要引入“信用奖励机制”,对于贡献较大的节点可获取数据优先权,这是今后算法优化研究的重要方向。%In the current computer network environment, P2P(peer-to-peer) is the foundations of the whole Internet frame. This paper describes the operation environment of P2P network and the application of P2P technology in this environment. Based on the current application and development of P2P network, the characteristic of P2P network group communication mechanism is analyzed, and the optimization of P2P network group algorithms proposed, thus to fairly achieve the optimization target of P2P network group communication. Meanwhile, it is necessary to introduce the “reputation reward mechanism”, and thus for the node with great contribution to acquire the data priority, and this would be the important direction for algorithm optimization research.

  13. Differential gene expression patterns and colocalization of ATP-gated P2X6/P2X4 ion channels during rat small intestine ontogeny.

    Science.gov (United States)

    Padilla, Karla; Gonzalez-Mendoza, David; Berumen, Laura C; Escobar, Jesica E; Miledi, Ricardo; García-Alcocer, Guadulupe

    2016-07-01

    Gene coding for ATP-gated receptor ion channels (P2X1-7) has been associated with the developmental process in various tissues; among these ion channel subtypes, P2X6 acts as a physiological regulator of P2X4 receptor functions when the two receptors form heteroreceptors. The P2X4 receptor is involved in pain sensation, the inflammatory process, and body homeostasis by means of Mg(2+) absorption through the intestine. The small intestine is responsible for the absorption and digestion of nutrients; throughout its development, several gene expressions are induced that are related to nutrients received, metabolism, and other intestine functions. Previous work has shown a differential P2X4 and P2X6 protein distribution in the small intestine of newborn and adult rats; however, it is not well-known at what age the change in the relationship between the gene and protein expression occurs and whether or not these receptors are colocalized. In this work, we evaluate P2X4 and P2X6 gene expression patterns by qPCR from embryonic (E18, P0, P7, P17, P30) to adult age in rat gut, as well as P2X6/P2X4 colocalization using qRT-PCR and confocal immunofluorescence in proximal and distal small intestine sections. The results showed that P2X6 and P2X4 gene expression levels of both receptors decreased at the embryonic-perinatal transition, whereas from ages P17 to P30 (suckling-weaning transition) both receptors increased their gene expression levels. Furthermore, P2X4 and P2X6 proteins were expressed in a different way during rat small intestine development, showing a higher colocalization coefficient at age P30 in both intestine regions. Those results suggest that purinergic receptors may play a role in intestinal maturation, which is associated with age and intestinal region.

  14. Residual Chemosensory Capabilities in Double P2X2/P2X3 Purinergic Receptor Null Mice: Intraoral or Postingestive Detection?

    Science.gov (United States)

    Hallock, Robert M.; Tatangelo, Marco; Barrows, Jennell

    2009-01-01

    Mice lacking the purinergic receptors, P2X2 and P2X3 (P2X2/P2X3Dbl−/−), exhibit essentially no tastant-evoked activity in the chorda tympani and glossopharyngeal nerves and substantial loss of tastant-evoked behavior as measured in long-term intake experiments. To assess whether the residual chemically driven behaviors in these P2X2/P2X3Dbl−/− mice were attributable to postingestive detection or oropharyngeal detection of the compounds, we used brief access lickometer tests to assess the behavioral capabilities of the P2X2/P2X3Dbl−/− animals. The P2X2/P2X3Dbl−/− mice showed avoidance to high levels (10 mM quinine and 10–30 mM denatonium benzoate) of classical “bitter”-tasting stimuli in 24-h, 2-bottle preference tests but minimal avoidance of these substances in the lickometer tests, suggesting that the strong avoidance in the intake tests was largely mediated by post-oral chemosensors. Similarly, increases in consumption of 1 M sucrose by P2X2/P2X3Dbl−/− mice in long-term intake tests were not mirrored by increases in consumption of sucrose in lickometer tests, suggesting that sucrose detection in these mice is mediated by postingestive consequences. In contrast, in brief access tests, P2X2/P2X3Dbl−/− mice avoided citric acid and hydrochloric acid at the same concentrations as their wild-type counterparts, indicating that these weak acids activate oropharyngeal chemoreceptors. PMID:19833662

  15. P2X7受体在肿瘤中的表达及其意义%P2X7 receptor and its significances in tumor

    Institute of Scientific and Technical Information of China (English)

    仲小敏

    2015-01-01

    P2X7受体(P2X7R)是P2X家族受体的一员,分布于多种组织,参与细胞信号转导、炎症反应等多种生理功能.传统普遍认为,P2X7R是细胞毒性核苷酸受体的典型代表.近来,大量研究结果却证实,P2X7R还具有促进细胞增殖活性.P2X7R表达及功能异常与多种实体瘤及血液系统肿瘤相关.阐明P2X7R在肿瘤发生、发展中的作用对肿瘤的诊断、治疗及预后评估起重要的作用.%P2X7 receptor(P2X7R),a member of P2X receptors,is distributed to many tissues and plays an important role in cell signaling transduction,inflammatory reaction and so on.In the past,the P2X7R is often taken as an epitome of cytotoxic receptors.Over the years,numerous experiments have led us to adopt a new view,that P2X7R is a growth-promoting receptor.The abnormal expression and function of P2X7R are closely related to many solid tumors and hematological neoplasms.Thus,the better understanding of P2X7R in cancer opens promising perspectives for the diagnosis,treatments and prognostic evaluation of neoplasms.

  16. Comparison of relaxation responses of cavernous and trigonal smooth muscles from rabbits by alpha1-adrenoceptor antagonists; prazosin, terazosin, doxazosin, and tamsulosin.

    Science.gov (United States)

    Seo, K. K.; Lee, M. Y.; Lim, S. W.; Kim, S. C.

    1999-01-01

    Alpha1a-adrenergic receptor (AR) primarily mediates the contraction of the prostatic and cavernous smooth muscles. Among clinically available alpha1-AR antagonists for the medical management of benign prostatic hyperplasia (BPH), tamsulosin has a modest selectivity for alpha1A- and alpha1D- over alpha1B-ARs. To compare the effects of various alpha1-AR antagonists on relaxation responses of cavernous and trigonal smooth muscles, isometric tension studies with relatively selective (tamsulosin) and non-selective (prazosin, doxazosin, and terazosin) alpha1A-AR antagonists, were conducted in the cavernous and trigonal muscle strips of rabbits (n=10 each). Tamsulosin had the strongest inhibitory effect on contraction of trigonal smooth muscle among the various alpha1-AR antagonists, and the inhibitory activities of prazosin, doxazosin, and terazosin were not statistically different. All alpha1-AR antagonists caused concentration-dependent relaxation of the cavernous muscle strips. Tamsulosin was shown to have greater potency than prazosin (more than 100-fold), doxazosin (more than 1000-fold), and terazosin (more than 1000-fold), in relaxation of cavernous smooth muscle. In conclusion, tamsulosin might be the most effective drug among the four commonly used alpha1-AR antagonists for the medical management of BPH. Tamsulosin might be a potential substitute for phentolamine in combination with vasoactive agents as an intracavernous injection therapy for patients with erectile dysfunction. PMID:10102527

  17. Antagonistic formation motion of cooperative agents

    Institute of Scientific and Technical Information of China (English)

    卢婉婷; 代明香; 薛方正

    2015-01-01

    This paper investigates a new formation motion problem of a class of first-order multi-agent systems with antagonis-tic interactions. A distributed formation control algorithm is proposed for each agent to realize the antagonistic formation motion. A sufficient condition is derived to ensure that all agents make an antagonistic formation motion in a distributed manner. It is shown that all agents can be spontaneously divided into several groups, and agents in the same group collab-orate while agents in different groups compete. Finally, a numerical simulation is included to demonstrate our theoretical results.

  18. Antagonists of the kappa opioid receptor.

    Science.gov (United States)

    Urbano, Mariangela; Guerrero, Miguel; Rosen, Hugh; Roberts, Edward

    2014-05-01

    The research community has increasingly focused on the development of OPRK antagonists as pharmacotherapies for the treatment of depression, anxiety, addictive disorders and other psychiatric conditions produced or exacerbated by stress. Short-acting OPRK antagonists have been recently developed as a potential improvement over long-acting prototypic ligands including nor-BNI and JDTic. Remarkably the short-acting LY2456302 is undergoing phase II clinical trials for the augmentation of the antidepressant therapy in treatment-resistant depression. This Letter reviews relevant chemical and pharmacological advances in the identification and development of OPRK antagonists.

  19. 29 CFR 553.30 - Occasional or sporadic employment-section 7(p)(2).

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Occasional or sporadic employment-section 7(p)(2). 553.30... Other Exemptions § 553.30 Occasional or sporadic employment-section 7(p)(2). (a) Section 7(p)(2) of the... basis to qualify for exemption under section 7(p)(2), the employee's decision to work in a...

  20. The role of P2X7 receptors in a rodent PCP-induced schizophrenia model

    OpenAIRE

    Bence Koványi; Cecilia Csölle; Stefano Calovi; Adrienn Hanuska; Erzsébet Kató; László Köles; Anindya Bhattacharya; József Haller; Beáta Sperlágh

    2016-01-01

    P2X7 receptors (P2X7Rs) are ligand-gated ion channels sensitive to extracellular ATP. Here we examined for the first time the role of P2X7R in an animal model of schizophrenia. Using the PCP induced schizophrenia model we show that both genetic deletion and pharmacological inhibition of P2X7Rs alleviate schizophrenia-like behavioral alterations. In P2rx7+/+ mice, PCP induced hyperlocomotion, stereotype behavior, ataxia and social withdrawal. In P2X7 receptor deficient mice (P2rx7−/−), the soc...

  1. Involvement of the P2X7-NLRP3 axis in leukemic cell proliferation and death

    OpenAIRE

    Erica Salaro; Alessia Rambaldi; Simonetta Falzoni; Francesca Saveria Amoroso; Alessia Franceschini; Alba Clara Sarti; Massimo Bonora; Francesco Cavazzini; Gian Matteo Rigolin; Maria Ciccone; Valentina Audrito; Silvia Deaglio; Pablo Pelegrin; Paolo Pinton; Antonio Cuneo

    2016-01-01

    Lymphocyte growth and differentiation are modulated by extracellular nucleotides and P2 receptors. We previously showed that the P2X7 receptor (P2X7R or P2RX7) is overexpressed in circulating lymphocytes from chronic lymphocytic leukemia (CLL) patients. In the present study we investigated the P2X7R/NLRP3 inflammasome axis in lymphocytes from a cohort of 23 CLL patients. P2X7R, ASC and NLRP3 were investigated by Western blot, PCR and transfection techniques. P2X7R was overexpressed and correl...

  2. The effect of external divalent cations on spontaneous non-selective cation channel currents in rabbit portal vein myocytes.

    Science.gov (United States)

    Albert, A P; Large, W A

    2001-10-15

    1. The effects of external divalent cations on spontaneous single non-selective cation channel currents were studied in outside-out patches from rabbit portal vein smooth muscle cells in K+-free conditions. 2. In an external medium containing 1.5 mM Ca2+ (Ca2+o) the majority of spontaneous channel currents had a unitary conductance of 23 pS, reversal potential (Vr) of +10 mV and a low open probability (Po) at negative patch potentials. Some channels opened to a lower conductance state of about 13 pS suggesting that the cation channels have two conductance states. Open time and burst duration distributions could both be described by two exponentials with time constants of about of 1 ms and 7 ms for open times and 3 ms and 16 ms for burst durations. 3. In 0 Ca2+o the majority of spontaneous cation channels had a unitary conductance of 13 pS and Vr was shifted to +4 mV. Moreover the longer open time and longer burst duration time constants were both reduced to approximately half the values in 1.5 mM Ca2+o. 4. Compared to 0 Ca2+o the single channel currents in 3 microM and 100 microM Ca2+o had a 5- to 6-fold increase in Po which was accompanied by increases in both open times and burst durations. In 3 microM and 100 microM Ca2+o the unitary conductance of the single channel currents was between 22 and 26 pS. 5. At positive membrane potentials the single channel currents had an increased Po compared to negative potentials which was associated with increased open times and burst durations but these values were similar in 3 microM, 100 microM and 1.5 mM Ca2+o. 6. In 1.5 mM Sr2+o and 1.5 mM Ba2+o channels opened to the higher conductance state of about 22-25 pS and had a 3- to 7-fold greater Po than in 0 Ca2+o. 7. In conclusion, external divalent cations have marked effects on the unitary conductance and kinetic behaviour of non-selective cation channels in rabbit portal vein smooth muscle cells.

  3. Accelerated habit formation following amphetamine exposure is reversed by D1, but enhanced by D2, receptor antagonists

    Directory of Open Access Journals (Sweden)

    Andrew John Dudley Nelson

    2013-05-01

    Full Text Available Repeated exposure to the psychostimulant amphetamine has been shown to disrupt goal-directed instrumental actions and promote the early and abnormal development of goal-insensitive habitual responding (Nelson and Killcross, 2006. To investigate the neuropharmacological specificity of this effect as well as restore goal-directed responding in animals with pre-training amphetamine exposure, animals were treated with the non-selective dopamine antagonist α-flupenthixol, the selective D1 antagonist SCH 23390 or the selective D2 antagonist eticlopride, prior to instrumental training (3 sessions. Subsequently, the reinforcer was paired with LiCL-induced gastric-malaise and animals were given a test of goal-sensitivity both in extinction and reacquisition. The effect of these dopaminergic antagonists on the sensitivity of lever press performance to outcome devaluation was assessed in animals with pre-training exposure to amphetamine (Experiments 1a-1c or in non-sensitized animals (Experiment 2. Both α-flupenthixol and SCH23390 reversed accelerated habit formation following amphetamine sensitization. However, eticlopride appeared to enhance this effect and render instrumental performance compulsive as these animals were unable to inhibit responding both in extinction and reacquisition, even though a consumption test confirmed they had acquired an aversion to the reinforcer. These findings demonstrate that amphetamine induced-disruption of goal-directed behaviour is mediated by activity at distinct dopamine receptor subtypes and may represent a putative model of the neurochemical processes involved in the loss of voluntary control over behaviour.

  4. Distribution of P2Y6 and P2Y12 receptor: their colocalization with calbindin, calretinin and nitric oxide synthase in the guinea pig enteric nervous system.

    Science.gov (United States)

    Xiang, Zhenghua; Burnstock, Geoffrey

    2006-04-01

    The distribution of P2Y(6) and P2Y(12) receptor-immunoreactive (ir) neurons and fibers and their coexistence with calbindin, calretinin and nitric oxide synthase (NOS) has been investigated with single and double labeling immunostaining methods. The results showed that 30-36% of the ganglion cells in the myenteric plexus are strongly P2Y(6) receptor-ir neurons; they are distributed widely in the myenteric plexus of stomach, jejunum, ileum and colon, but not in the submucosal plexus, with a typical morphology of multipolar neurons with a long axon-like process. About 42-46% of ganglion cells in both the myenteric and submucosal plexuses show P2Y(12) receptor-ir. About 28-35% of P2Y(6) receptor-ir neurons were found to coexist with NOS and 41-47% of them coexist with calretinin, but there was no coexistence of P2Y(6) receptor-ir with calbindin. In contrast, all P2Y(12) receptor-ir neurons were immunopositive for calbindin, although occasionally P2Y(12) receptor-ir neurons without calbindin immunoreactivity were found, while none of the P2Y(12) receptor-ir neurons were found to coexist with calretinin or NOS in the gastrointestinal system of guinea pig. The P2Y(12) receptor-ir neurons coexpressing calbindin-ir in the small intestine are Dogiel type II/AH, intrinsic primary afferent neurons.

  5. Expression of OmpP2A and OmpP2B is not required for pustule formation by Haemophilus ducreyi in human volunteers.

    Science.gov (United States)

    Janowicz, Diane; Luke, Nicole R; Fortney, Kate R; Katz, Barry P; Campagnari, Anthony A; Spinola, Stanley M

    2006-03-01

    Haemophilus ducreyi express two porin proteins, termed OmpP2A and OmpP2B. To test whether expression of OmpP2A and OmpP2B was necessary for virulence in humans, eight volunteers were experimentally infected with the parent (35000HP) in one arm and a double OmpP2A OmpP2B mutant (35000HP::P2AB) in the other arm. The pustule formation rates were 58.3% (95% CI, 33.2-83.5%) for the parent and 41.7% (95% CI, 19.3-64.0%) for the mutant (P=0.25). Biopsy of 35000HP and 35000HP::P2AB-infected sites yielded similar amounts of bacteria in quantitative culture. These results indicate that expression of OmpP2A and OmpP2B is not necessary to initiate disease or to progress to pustule formation in humans.

  6. Molecular mechanism for opioid dichotomy: bidirectional effect of μ-opioid receptors on P2X₃ receptor currents in rat sensory neurones.

    Science.gov (United States)

    Chizhmakov, Igor; Kulyk, Vyacheslav; Khasabova, Iryna; Khasabov, Sergey; Simone, Donald; Bakalkin, Georgy; Gordienko, Dmitri; Verkhratsky, Alexei; Krishtal, Oleg

    2015-06-01

    Here, we describe a molecular switch associated with opioid receptors-linked signalling cascades that provides a dual opioid control over P2X3 purinoceptor in sensory neurones. Leu-enkephalin inhibited P2X3-mediated currents with IC50 ~10 nM in ~25% of small nociceptive rat dorsal root ganglion (DRG) neurones. In contrast, in neurones pretreated with pertussis toxin leu-enkephalin produced stable and significant increase of P2X3 currents. All effects of opioid were abolished by selective μ-opioid receptor antagonist D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP), nonselective inhibitor naloxone, and by PLC inhibitor U73122. Thus, we discovered a dual link between purinoceptors and μ-opioid receptors: the latter exert both inhibitory (pertussis toxin-sensitive) and stimulatory (pertussis toxin-insensitive) actions on P2X3 receptors through phospholipase C (PLC)-dependent pathways. This dual opioid control of P2X3 receptors may provide a molecular explanation for dichotomy of opioid therapy. Pharmacological control of this newly identified facilitation/inhibition switch may open new perspectives for the adequate medical use of opioids, the most powerful pain-killing agents known today.

  7. Subfailure overstretch injury leads to reversible functional impairment and purinergic P2X7 receptor activation in intact vascular tissue

    Directory of Open Access Journals (Sweden)

    Weifeng Luo

    2016-09-01

    Full Text Available Vascular stretch injury is associated with blunt trauma, vascular surgical procedures, and harvest of human saphenous vein for use in vascular bypass grafting. A model of subfailure overstretch in rat abdominal aorta was developed to characterize surgical vascular stretch injury. Longitudinal stretch of rat aorta was characterized ex vivo. Stretch to the haptic endpoint where the tissues would no longer lengthen, occurred at twice the resting length. The stress produced at this length was greater than physiologic mechanical forces but well below the level of mechanical disruption. Functional responses were determined in a muscle bath and this subfailure overstretch injury led to impaired smooth muscle function that was partially reversed by treatment with purinergic receptor (P2X7R antagonists. These data suggest that vasomotor dysfunction caused by subfailure overstretch injury may be due to activation of P2X7R. These studies have implications for our understanding of mechanical stretch injury of blood vessels and offer novel therapeutic opportunities.

  8. Sensitization by pulmonary reactive oxygen species of rat vagal lung C-fibers: the roles of the TRPV1, TRPA1, and P2X receptors.

    Directory of Open Access Journals (Sweden)

    Ting Ruan

    Full Text Available Sensitization of vagal lung C-fibers (VLCFs induced by mediators contributes to the pathogenesis of airway hypersensitivity, which is characterized by exaggerated sensory and reflex responses to stimulants. Reactive oxygen species (ROS are mediators produced during airway inflammation. However, the role of ROS in VLCF-mediated airway hypersensitivity has remained elusive. Here, we report that inhalation of aerosolized 0.05% H2O2 for 90 s potentiated apneic responses to intravenous capsaicin (a TRPV1 receptor agonist, α,β-methylene-ATP (a P2X receptor agonist, and phenylbiguanide (a 5-HT3 receptor agonist in anesthetized rats. The apneic responses to these three stimulants were abolished by vagatomy or by perivagal capsaicin treatment, a procedure that blocks the neural conduction of VLCFs. The potentiating effect of H2O2 on the apneic responses to these VLCF stimulants was prevented by catalase (an enzyme that degrades H2O2 and by dimethylthiourea (a hydroxyl radical scavenger. The potentiating effect of H2O2 on the apneic responses to capsaicin was attenuated by HC-030031 (a TRPA1 receptor antagonist and by iso-pyridoxalphosphate-6-azophenyl-2',5'-disulphonate (a P2X receptor antagonist. The potentiating effect of H2O2 on the apneic responses to α,β-methylene-ATP was reduced by capsazepine (a TRPV1 receptor antagonist, and by HC-030031. The potentiating effect of H2O2 on the apneic responses to phenylbiguanide was totally abolished when all three antagonists were combined. Consistently, our electrophysiological studies revealed that airway delivery of aerosolized 0.05% H2O2 for 90 s potentiated the VLCF responses to intravenous capsaicin, α,β-methylene-ATP, and phenylbiguanide. The potentiating effect of H2O2 on the VLCF responses to phenylbiguanide was totally prevented when all antagonists were combined. Inhalation of 0.05% H2O2 indeed increased the level of ROS in the lungs. These results suggest that 1 increased lung ROS sensitizes

  9. P2X1, P2X4, and P2X7 Receptor Knock Out Mice Expose Differential Outcome of Sepsis Induced by α-Haemolysin Producing Escherichia coli

    DEFF Research Database (Denmark)

    Greve, Anne-Sofie; Skals, Marianne; Fagerberg, Steen K

    2017-01-01

    α-haemolysin (HlyA)-producing Escherichia coli commonly inflict severe urinary tract infections, including pyelonephritis, which comprises substantial risk for sepsis. In vitro, the cytolytic effect of HlyA is mainly mediated by ATP release through the HlyA pore and subsequent P2X1/P2X7 receptor...

  10. P2X3 Receptors Mediate Visceral Hypersensitivity during Acute Chemically-Induced Colitis and in the Post-Inflammatory Phase via Different Mechanisms of Sensitization

    Science.gov (United States)

    Deiteren, Annemie; van der Linden, Laura; de Wit, Anouk; Ceuleers, Hannah; Buckinx, Roeland; Timmermans, Jean-Pierre; Moreels, Tom G.; Pelckmans, Paul A.; De Man, Joris G.; De Winter, Benedicte Y.

    2015-01-01

    Objectives Experiments using P2X3 knock-out mice or more general P2X receptor antagonists suggest that P2X3 receptors contribute to visceral hypersensitivity. We aimed to investigate the effect of the selective P2X3 antagonist A-317491 on visceral sensitivity under physiological conditions, during acute colitis and in the post-inflammatory phase of colitis. Methods Trinitrobenzene sulphonic-acid colitis was monitored by colonoscopy: on day 3 to confirm the presence of colitis and then every 4 days, starting from day 10, to monitor convalescence and determine the exact timepoint of endoscopic healing in each rat. Visceral sensitivity was assessed by quantifying visceromotor responses to colorectal distension in controls, rats with acute colitis and post-colitis rats. A-317491 was administered 30 min prior to visceral sensitivity testing. Expression of P2X3 receptors (RT-PCR and immunohistochemistry) and the intracellular signalling molecules cdk5, csk and CASK (RT-PCR) were quantified in colonic tissue and dorsal root ganglia. ATP release in response to colorectal distension was measured by luminiscence. Results Rats with acute TNBS-colitis displayed significant visceral hypersensitivity that was dose-dependently, but not fully, reversed by A-317491. Hypersenstivity was accompanied by an increased colonic release of ATP. Post-colitis rats also displayed visceral hypersensitivity that was dose-dependently reduced and fully normalized by A-317491 without increased release of ATP. A-317491 did not modify visceral sensitivity in controls. P2X3 mRNA and protein expression in the colon and dorsal root ganglia were similar in control, acute colitis and post-colitis groups, while colonic mRNA expression of cdk5, csk and CASK was increased in the post-colitis group only. Conclusions These findings indicate that P2X3 receptors are not involved in sensory signaling under physiological conditions whereas they modulate visceral hypersensitivity during acute TNBS-colitis and even

  11. P2X3 receptors mediate visceral hypersensitivity during acute chemically-induced colitis and in the post-inflammatory phase via different mechanisms of sensitization.

    Directory of Open Access Journals (Sweden)

    Annemie Deiteren

    Full Text Available Experiments using P2X3 knock-out mice or more general P2X receptor antagonists suggest that P2X3 receptors contribute to visceral hypersensitivity. We aimed to investigate the effect of the selective P2X3 antagonist A-317491 on visceral sensitivity under physiological conditions, during acute colitis and in the post-inflammatory phase of colitis.Trinitrobenzene sulphonic-acid colitis was monitored by colonoscopy: on day 3 to confirm the presence of colitis and then every 4 days, starting from day 10, to monitor convalescence and determine the exact timepoint of endoscopic healing in each rat. Visceral sensitivity was assessed by quantifying visceromotor responses to colorectal distension in controls, rats with acute colitis and post-colitis rats. A-317491 was administered 30 min prior to visceral sensitivity testing. Expression of P2X3 receptors (RT-PCR and immunohistochemistry and the intracellular signalling molecules cdk5, csk and CASK (RT-PCR were quantified in colonic tissue and dorsal root ganglia. ATP release in response to colorectal distension was measured by luminiscence.Rats with acute TNBS-colitis displayed significant visceral hypersensitivity that was dose-dependently, but not fully, reversed by A-317491. Hypersenstivity was accompanied by an increased colonic release of ATP. Post-colitis rats also displayed visceral hypersensitivity that was dose-dependently reduced and fully normalized by A-317491 without increased release of ATP. A-317491 did not modify visceral sensitivity in controls. P2X3 mRNA and protein expression in the colon and dorsal root ganglia were similar in control, acute colitis and post-colitis groups, while colonic mRNA expression of cdk5, csk and CASK was increased in the post-colitis group only.These findings indicate that P2X3 receptors are not involved in sensory signaling under physiological conditions whereas they modulate visceral hypersensitivity during acute TNBS-colitis and even more so in the post

  12. Peripheral mGluR5 antagonist attenuated craniofacial muscle pain and inflammation but not mGluR1 antagonist in lightly anesthetized rats.

    Science.gov (United States)

    Lee, Ho Jeong; Choi, Hyo Soon; Ju, Jin Sook; Bae, Yong Chul; Kim, Sung Kyo; Yoon, Young Wook; Ahn, Dong Kuk

    2006-10-16

    The present study investigated the role of peripheral group I metabotropic glutamate receptors (mGluRs) in MO-induced nociceptive behaviour and inflammation in the masseter muscles of lightly anesthetized rats. Experiments were carried out on male Sprague-Dawley rats weighing 300-400 g. After initial anesthesia with sodium pentobarbital (40 mg/kg, i.p.), one femoral vein was cannulated and connected to an infusion pump for intravenous infusion of sodium pentobarbital. The rate of infusion was adjusted to provide a constant level of anesthesia. Mustard oil (MO, 30 microl) was injected into the mid-region of the left masseter muscle via a 30-gauge needle over 10s. After 30 microl injection of 5, 10, 15, or 20% MO into the masseter muscle, the total number of hindpaw shaking behaviour and extravasated Evans' blue dye concentration in the masseter muscle were significantly higher in the MO-treated group in a dose-dependent manner compared with the vehicle (mineral oil)-treated group. Intramuscular pretreatment with 3 or 5% lidocaine reduced MO-induced hindpaw shaking behaviour and increases in extravasated Evans' blue dye concentration. Intramuscular pretreatment with 5 mM MCPG, non-selective group I/II mGluR antagonist, or MPEP, a selective group I mGluR5 antagonist, produced a significant attenuation of MO-induced hindpaw shaking behaviour and increases in extravasated Evans' blue dye concentration in the masseter muscle while LY367385, a selective group I mGluR1 antagonist, did not affect MO-induced nociceptive behaviour and inflammation in the masseter muscle. These results indicate that peripheral mGluR5 plays important role in mediating MO-induced nociceptive behaviour and inflammation in the craniofacial muscle.

  13. 基于P2P应用的网络测量探讨%The Discussion about Network Measure of P2P application

    Institute of Scientific and Technical Information of China (English)

    刘伟

    2011-01-01

    Through the P2P network and the definition of technology,and the related measurement techniques are described,we can get further awareness and understanding the importance and difficulty of measurement on P2P network application.The network measurement technology and method is proposed to solve the P2P application.%本文通过P2P网络和技术的定义,以及相关测量技术的描述,进一步认识和理解测量对P2P网络应用的重要性和困难性。并提出了较好解决P2P应用的网络测量技术和方法。

  14. Institute of Information Network Technology%P2P-SIP融合及P2P-SIP系统设计

    Institute of Scientific and Technical Information of China (English)

    吴亮

    2010-01-01

    随着现代通信技术的不断发展,P2P(对等网络)技术与SIP(会话初始化协议)之间相互融合成为当前研究的一个热点.文章首先介绍了P2P技术和SIP协议,随后研究怎样将P2P架构与SIP系统进行融合,重点讨论了P2P-SIP的实现过程,包括P2P-SIP终端如何使用SIP协议携带P2P消息实现节点的发现、加入、离开和用户注册等过程.

  15. Regeneration of transgenic citrus plants under non selective conditions results in high-frequency recovery of plants with silenced transgenes.

    Science.gov (United States)

    Domínguez, A; Fagoaga, C; Navarro, L; Moreno, P; Peña, L

    2002-06-01

    Insertion of foreign DNA into plant genomes frequently results in the recovery of transgenic plants with silenced transgenes. To investigate to what extent regeneration under selective conditions limits the recovery of transgenic plants showing gene silencing in woody species, Mexican lime [ Citrus aurantifolia (Christm.) Swing.] plants were transformed with the p25 coat protein gene of Citrus tristeza virus (CTV) with or without selection for nptII and uidA. Strikingly, more than 30% of the transgenic limes regenerated under non-selective conditions had silenced transgenes, and in all cases silencing affected all the three transgenes incorporated. These results indicate that the frequency of transgene silencing may be greatly underestimated when the rate of silencing is estimated from the number of regenerants obtained under selective conditions. To our knowledge, this is the first report in which the frequency of gene silencing after transformation has been quantified. When the integration pattern of T-DNA was analyzed in silenced and non-silenced lines, it was observed that inverted repeats as well as direct repeats and even single integrations were able to trigger gene silencing. Gene silencing has often been associated with the insertion of DNA sequences as inverted repeats. Interestingly, here, direct repeats and single-copy insertions were found in both silenced and non-silenced lines, suggesting that the presence of inverted-repeat T-DNAs and the subsequent formation of dsRNAs triggering gene silencing cannot account for all silencing events.

  16. Combining Non Selective Gas Sensors on a Mobile Robot for Identification and Mapping of Multiple Chemical Compounds

    Directory of Open Access Journals (Sweden)

    Victor Hernandez Bennetts

    2014-09-01

    Full Text Available In this paper, we address the task of gas distribution modeling in scenarios where multiple heterogeneous compounds are present. Gas distribution modeling is particularly useful in emission monitoring applications where spatial representations of the gaseous patches can be used to identify emission hot spots. In realistic environments, the presence of multiple chemicals is expected and therefore, gas discrimination has to be incorporated in the modeling process. The approach presented in this work addresses the task of gas distribution modeling by combining different non selective gas sensors. Gas discrimination is addressed with an open sampling system, composed by an array of metal oxide sensors and a probabilistic algorithm tailored to uncontrolled environments. For each of the identified compounds, the mapping algorithm generates a calibrated gas distribution model using the classification uncertainty and the concentration readings acquired with a photo ionization detector. The meta parameters of the proposed modeling algorithm are automatically learned from the data. The approach was validated with a gas sensitive robot patrolling outdoor and indoor scenarios, where two different chemicals were released simultaneously. The experimental results show that the generated multi compound maps can be used to accurately predict the location of emitting gas sources.

  17. Combining non selective gas sensors on a mobile robot for identification and mapping of multiple chemical compounds.

    Science.gov (United States)

    Bennetts, Victor Hernandez; Schaffernicht, Erik; Pomareda, Victor; Lilienthal, Achim J; Marco, Santiago; Trincavelli, Marco

    2014-09-17

    In this paper, we address the task of gas distribution modeling in scenarios where multiple heterogeneous compounds are present. Gas distribution modeling is particularly useful in emission monitoring applications where spatial representations of the gaseous patches can be used to identify emission hot spots. In realistic environments, the presence of multiple chemicals is expected and therefore, gas discrimination has to be incorporated in the modeling process. The approach presented in this work addresses the task of gas distribution modeling by combining different non selective gas sensors. Gas discrimination is addressed with an open sampling system, composed by an array of metal oxide sensors and a probabilistic algorithm tailored to uncontrolled environments. For each of the identified compounds, the mapping algorithm generates a calibrated gas distribution model using the classification uncertainty and the concentration readings acquired with a photo ionization detector. The meta parameters of the proposed modeling algorithm are automatically learned from the data. The approach was validated with a gas sensitive robot patrolling outdoor and indoor scenarios, where two different chemicals were released simultaneously. The experimental results show that the generated multi compound maps can be used to accurately predict the location of emitting gas sources.

  18. Benzodiazepine receptor antagonists for hepatic encephalopathy

    DEFF Research Database (Denmark)

    Als-Nielsen, B; Gluud, L L; Gluud, C

    2004-01-01

    Hepatic encephalopathy may be associated with accumulation of substances that bind to a receptor-complex in the brain resulting in neural inhibition. Benzodiazepine receptor antagonists may have a beneficial effect on patients with hepatic encephalopathy.......Hepatic encephalopathy may be associated with accumulation of substances that bind to a receptor-complex in the brain resulting in neural inhibition. Benzodiazepine receptor antagonists may have a beneficial effect on patients with hepatic encephalopathy....

  19. The TV Programing System Based on P2 Techaology%基于P2技术的电视制作系统

    Institute of Scientific and Technical Information of China (English)

    江铁成

    2007-01-01

    P2技术作为新一代的存储介质必将在电视节目制作系统中占据着一个重要的地位.本文描述了P2设备的特点,论述了建立在P2技术上的电视制作系统的技术要点.

  20. Full length and protease domain activity of chikungunya virus nsP2 differ from other alphavirus nsP2 proteases in recognition of small peptide substrates

    OpenAIRE

    Saisawang, Chonticha; Sillapee, Pornpan; Sinsirimongkol, Kwanhathai; Ubol, Sukathida; Smith, Duncan R.; Ketterman, Albert J.

    2015-01-01

    Alphavirus nsP2 proteins are multifunctional and essential for viral replication. The protease role of nsP2 is critical for virus replication as only the virus protease activity is used for processing of the viral non-structural polypeptide. Chikungunya virus is an emerging disease problem that is becoming a world-wide health issue. We have generated purified recombinant chikungunya virus nsP2 proteins, both full length and a truncated protease domain from the C-terminus of the nsP2 protein. ...

  1. Humoral and Cell-mediated Autoimmune Reactions to Human Acidic Ribosomal P2 Protein in Individuals Sensitized to Aspergillus fumigatus P2 Protein

    Science.gov (United States)

    Mayer, Christina; Appenzeller, Ulrich; Seelbach, Heike; Achatz, Gernot; Oberkofler, Hannes; Breitenbach, Michael; Blaser, Kurt; Crameri, Reto

    1999-01-01

    A panel of cDNAs encoding allergenic proteins was isolated from an Aspergillus fumigatus cDNA library displayed on the surface of filamentous phage. Solid phase–immobilized serum immunoglobulin E (IgE) from A. fumigatus–allergic individuals was used to enrich phage displaying IgE-binding molecules. One of the cDNAs encoded a 11.1-kD protein that was identified as acidic ribosomal phosphoprotein type 2 (P2 protein). The allergen, formally termed rAsp f 8, shares >62% sequence identity and >84% sequence homology to corresponding eukaryotic P2 proteins, including human P2 protein. The sequences encoding human and fungal P2 protein were subcloned, expressed in Escherichia coli as His6-tagged fusion proteins, and purified by Ni2+–chelate affinity chromatography. Both recombinant P2 proteins were recognized by IgE antibodies from allergic individuals sensitized to the A. fumigatus P2 protein and elicited strong type 1–specific skin reactions in these individuals. Moreover, human and fungal P2 proteins induced proliferative responses in peripheral blood mononuclear cells of A. fumigatus– allergic subjects sensitized to the fungal P2 protein. These data provide strong evidence for in vitro and in vivo humoral and cell-mediated autoreactivity to human P2 protein in patients suffering from chronic A. fumigatus allergy. PMID:10224291

  2. On Potentially K1,4+P2-graphic Sequences%蕴含K1,4+P2的可图序列

    Institute of Scientific and Technical Information of China (English)

    王艳

    2008-01-01

    本文刻划了蕴含K1,4+P2的可图序列,其中K1,4+P2是向完全二部图K1,4添加一条被剖分的边后构成的简单图.%In this paper, we characterize the potentially K1,4+P2-graphic sequences, where K1,4+P2 be a graph obtained by adding an edge e which is subdivided to complete bipartite graph K1,4.

  3. 可管理的P2P模式在IPTV中的应用%Application of a Manageable P2P Mode in IPTV System

    Institute of Scientific and Technical Information of China (English)

    邓亮; 刘勇

    2007-01-01

    本文介绍并分析了传统的P2P技术及P2P流媒体服务系统的工作原理和响应流程,对其优势和局限性进行了描述.进而提出了一种可管理的P2P模式,并将其应用到IPTV系统中,提出了一种可管理P2P(MP2P)模式的IPTV媒体交付网络.

  4. IPTV网络中CND与P2P结合的技术分析%The Technical Analysis for Combining CND and P2P in IPTV Network

    Institute of Scientific and Technical Information of China (English)

    宋利

    2011-01-01

    P2P-IPTV系统是目前IPTV应用技术发展中一个新的研究方向。针对P2P-IPTV技术发展中存在的问题进行了研究。在介绍了传统的IPTV中CDN系统架构的基础上,分析了该技术开发过程中可能遇到的难题;在讨论了P2P-IPTV技术解决上述难题优势所在的基础上,分析了IPTV网络中CDN与P2P技术结合点。%P2P-IPTV system is a new research topic in IPTV application technology development at present.In this paper,some problems which exist in P2P-IPTV technology development have been studied.Based on the introduction of the traditional CDN architecture in IPTV,this paper gives an analysis of the problems which may arise in P2P-IPTV technology development process;based on the discussion of the advantages of P2P-IPTV technology in solving the above problems,this paper gives an analysis of the technology combining points between CDN and P2P in IPTV network.

  5. Full length and protease domain activity of chikungunya virus nsP2 differ from other alphavirus nsP2 proteases in recognition of small peptide substrates.

    Science.gov (United States)

    Saisawang, Chonticha; Sillapee, Pornpan; Sinsirimongkol, Kwanhathai; Ubol, Sukathida; Smith, Duncan R; Ketterman, Albert J

    2015-04-22

    Alphavirus nsP2 proteins are multifunctional and essential for viral replication. The protease role of nsP2 is critical for virus replication as only the virus protease activity is used for processing of the viral non-structural polypeptide. Chikungunya virus is an emerging disease problem that is becoming a world-wide health issue. We have generated purified recombinant chikungunya virus nsP2 proteins, both full length and a truncated protease domain from the C-terminus of the nsP2 protein. Enzyme characterization shows that the protease domain alone has different properties compared with the full length nsP2 protease. We also show chikungunya nsP2 protease possesses different substrate specificity to the canonical alphavirus nsP2 polyprotein cleavage specificity. Moreover, the chikungunya nsP2 also appears to differ from other alphavirus nsP2 in its distinctive ability to recognize small peptide substrates.

  6. Extracellular ATP activates NFAT-dependent gene expression in neuronal PC12 cells via P2X receptors

    Directory of Open Access Journals (Sweden)

    Becker Walter

    2011-09-01

    Full Text Available Abstract Background Treatment of neuronal PC12 cells with ATP induces depolarisation and increases intracellular calcium levels via purinergic receptors. In many cell types, sustained elevation of intracellular calcium levels cause changes in gene expression via activation of the transcription factor NFAT (nuclear factor of activated T cells. We have therefore characterised the signalling pathway by which ATP regulates NFAT-dependent gene expression in PC12 cells. Results The activation of NFAT transcriptional activity by extracellular ATP was characterised with the help of reporter gene assays. Treatment of PC12 cells with ATP elicited a dose-dependent increase in luciferase activity (EC50 = 78 μM. UTP, 4-benzoylbenzoyl ATP and α,β-methylene ATP did not mimic the effect of ATP, which was abolished by treatment with the P2X receptor antagonist pyridoxal-phosphate-6-azophenyl-2',4'-disulfonate (PPADS. This pharmacological characterisation provides evidence for a critical role of ionotropic P2X receptors. Blockade of L-type voltage-dependent calcium channels by nifedipine reduced the response of NFAT to ATP, indicating that a depolarisation-mediated calcium influx was required for maximal NFAT activation. Inhibition of store-operated calcium entry by the pyrazole derivative BTP2 also diminished ATP-dependent NFAT activation. Furthermore, ATP-induced NFAT activation was associated with the activation of the mitogen-activated protein kinases ERK1/2. Finally, treatment with ATP increased the levels of the NFAT target transcripts, RCAN1-4 (regulator of calcineurin and BDNF (brain derived neurotrophic factor. Conclusion The present data show that ATP induces NFAT-dependent changes in gene expression in PC12 cells by acting on P2X receptors. Maximal NFAT activation depends on both depolarisation-induced calcium influx and store-operated calcium entry and requires the activity of the protein phosphatase calcineurin and the mitogen-activated protein

  7. Functional properties of heteromeric P2X(1/5) receptors expressed in HEK cells and excitatory junction potentials in guinea-pig submucosal arterioles.

    Science.gov (United States)

    Surprenant, A; Schneider, D A; Wilson, H L; Galligan, J J; North, R A

    2000-07-01

    P2X receptors are ATP-gated cation channels; they form as homomers or heteromers from a family of seven related subunits. In particular, heteromeric channels comprising P2X(2) and P2X(3) subunits, or P2X(1) and P2X(5) subunits, show distinctive physiological and pharmacological properties in heterologous expression systems. There is substantial evidence that one of the native P2X receptors in sensory neurones corresponds to the P2X(2/3) heteromer, but there is no evidence for P2X(1/5) heteromers in native tissue. We recorded currents in response to activation of heteromeric P2X(1/5) receptors expressed in HEK293 cells to characterize further their functional properties. The ATP concentration-response curve had a threshold concentration of 1 nM, and a Hill slope of one. TNP-ATP was a weak partial agonist, and a non-competitive antagonist which inhibited maximal ATP currents by 60%. Increasing or decreasing pH from 7.3 shifted the ATP concentration-response curves to the right by fivefold and decreased the maximum current by 40%. Calcium permeability was lower than that observed for other P2X receptors (P(Ca)/P(Na) ratio=1.1). The nanomolar sensitivity of this receptor revealed a steady release of ATP from HEK293 cells, providing an extracellular concentration which ranged from 3 to 300 nM. Noradrenaline (0.3-30 microM) increased ATP-evoked currents by 35%; this facilitation occurred within 20 ms. We also recorded excitatory junction potentials (EJPs) from guinea-pig submucosal arterioles. EJPs were inhibited by suramin and PPADS (IC(50)s of 0.2 microM and 20 microM) but TNP-ATP (0.1-10 microM) inhibited EJPs by <30%. Noradrenaline (0.3-30 microM in the presence of phentolamine and propranolol) decreased EJPs in control preparations but facilitated EJPs by 5-20% in submucosal arterioles from reserpinized guinea-pigs. These properties are discussed in relation to P2X receptors underlying EJPs at autonomic neuroeffector junctions.

  8. P2X7 receptor blockade protects against cisplatin-induced nephrotoxicity in mice by decreasing the activities of inflammasome components, oxidative stress and caspase-3

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yuanyuan; Yuan, Fahuan; Cao, Xuejiao [Department of Nephrology, Xinqiao Hospital, PLA, Third Military Medical University, Chongqing 400037 (China); Zhai, Zhifang [Department of Dermatology, Southwest Hospital, Third Military Medical University, Chongqing 400038 (China); Gang Huang [Department of Medical Genetics, Third Military Medical University, Chongqing 430038 (China); Du, Xiang; Wang, Yiqin; Zhang, Jingbo; Huang, Yunjian; Zhao, Jinghong [Department of Nephrology, Xinqiao Hospital, PLA, Third Military Medical University, Chongqing 400037 (China); Hou, Weiping, E-mail: hwp0518@aliyun.com [Department of Nephrology, Xinqiao Hospital, PLA, Third Military Medical University, Chongqing 400037 (China)

    2014-11-15

    Nephrotoxicity is a common complication of cisplatin chemotherapy and thus limits the use of cisplatin in clinic. The purinergic 2X7 receptor (P2X7R) plays important roles in inflammation and apoptosis in some inflammatory diseases; however, its roles in cisplatin-induced nephrotoxicity remain unclear. In this study, we first assessed the expression of P2X7R in cisplatin-induced nephrotoxicity in C57BL/6 mice, and then we investigated the changes of renal function, histological injury, inflammatory response, and apoptosis in renal tissues after P2X7R blockade in vivo using an antagonist A-438079. Moreover, we measured the changes of nod-like receptor family, pyrin domain containing proteins (NLRP3) inflammasome components, oxidative stress, and proapoptotic genes in renal tissues in cisplatin-induced nephrotoxicity after treatment with A-438079. We found that the expression of P2X7R was significantly upregulated in the renal tubular epithelial cells in cisplatin-induced nephrotoxicity compared with that of the normal control group. Furthermore, pretreatment with A-438079 markedly attenuated the cisplatin-induced renal injury while lightening the histological damage, inflammatory response and apoptosis in renal tissue, and improved the renal function. These effects were associated with the significantly reduced levels of NLRP3 inflammasome components, oxidative stress, p53 and caspase-3 in renal tissues in cisplatin-induced nephrotoxicity. In conclusions, our studies suggest that the upregulated activity of P2X7R might play important roles in the development of cisplatin-induced nephrotoxicity, and P2X7R blockade might become an effective therapeutic strategy for this disease. - Highlights: • The P2X7R expression was markedly upregulated in cisplatin-induced nephrotoxicity. • P2X7R blockade significantly attenuated the cisplatin-induced renal injury. • P2X7R blockade reduced activities of NLRP3 inflammasome components in renal tissue. • P2X7R blockade

  9. P2Y12 Receptor Localizes in the Renal Collecting Duct and Its Blockade Augments Arginine Vasopressin Action and Alleviates Nephrogenic Diabetes Insipidus.

    Science.gov (United States)

    Zhang, Yue; Peti-Peterdi, Janos; Müller, Christa E; Carlson, Noel G; Baqi, Younis; Strasburg, David L; Heiney, Kristina M; Villanueva, Karie; Kohan, Donald E; Kishore, Bellamkonda K

    2015-12-01

    P2Y12 receptor (P2Y12-R) signaling is mediated through Gi, ultimately reducing cellular cAMP levels. Because cAMP is a central modulator of arginine vasopressin (AVP)-induced water transport in the renal collecting duct (CD), we hypothesized that if expressed in the CD, P2Y12-R may play a role in renal handling of water in health and in nephrogenic diabetes insipidus. We found P2Y12-R mRNA expression in rat kidney, and immunolocalized its protein and aquaporin-2 (AQP2) in CD principal cells. Administration of clopidogrel bisulfate, an irreversible inhibitor of P2Y12-R, significantly increased urine concentration and AQP2 protein in the kidneys of Sprague-Dawley rats. Notably, clopidogrel did not alter urine concentration in Brattleboro rats that lack AVP. Clopidogrel administration also significantly ameliorated lithium-induced polyuria, improved urine concentrating ability and AQP2 protein abundance, and reversed the lithium-induced increase in free-water excretion, without decreasing blood or kidney tissue lithium levels. Clopidogrel administration also augmented the lithium-induced increase in urinary AVP excretion and suppressed the lithium-induced increase in urinary nitrates/nitrites (nitric oxide production) and 8-isoprostane (oxidative stress). Furthermore, selective blockade of P2Y12-R by the reversible antagonist PSB-0739 in primary cultures of rat inner medullary CD cells potentiated the expression of AQP2 and AQP3 mRNA, and cAMP production induced by dDAVP (desmopressin). In conclusion, pharmacologic blockade of renal P2Y12-R increases urinary concentrating ability by augmenting the effect of AVP on the kidney and ameliorates lithium-induced NDI by potentiating the action of AVP on the CD. This strategy may offer a novel and effective therapy for lithium-induced NDI.

  10. Xerostomia: prevalence and pharmacotherapy. With special reference to beta-adrenoceptor antagonists.

    Science.gov (United States)

    Nederfors, T

    1996-01-01

    The main objective of this thesis was to estimate the prevalence of subjectively perceived dry mouth, xerostomia, in a representative general adult population, and the possible co-morbidity between xerostomia and on-going pharmacotherapy. Further, to evaluate the effects of beta-adrenoceptor antagonists on saliva flow rate and composition. The prevalence of xerostomia was evaluated by means of a questionnaire mailed to a random sample of 4.200 adult subjects living in the southern part of the province of Halland, Sweden. Three hundred men and equally many women aged 20, 30, 40, 50, 60, 70 and 80 years were selected from the national census register. From 3311 (81%) evaluable questionnaires was concluded that, in the studied population, 21.3% of the men and 27.3% of the women reported xerostomia. The difference between the sexes was statistically significant, women reporting higher prevalence of dry mouth than men. It was also found that xerostomia was significantly age-related. Further, it was demonstrated that there was a strong co-morbidity between reported prevalence of dry mouth and on-going pharmacotherapy. Generally, no specific drug or drug-group proved to be especially xerogenic, rather, polypharmacy was strongly correlated to reported symptoms of dry mouth, and it was also a significant correlation between increasing xerostomia and the number of medications taken. The effects of beta-adrenoceptor antagonists on saliva flow rate and composition were evaluated both in healthy volunteers and in hypertensive patients. The effects of one week of treatment with the non-selective (propranolol) and the beta 1-selective (atenolol) adrenoceptor antagonists were compared with that of placebo in three different clinical trials, including 38, 11 and 19 healthy volunteers, respectively. Two of these studies were focused on the effects on whole saliva secretion rate and composition and the third study on the secretions from the parotid and the submandibular

  11. Ion channel regulation by phosphoinositides analyzed with VSPs-PI(4,5)P2 affinity, phosphoinositide selectivity, and PI(4,5)P2 pool accessibility.

    Science.gov (United States)

    Rjasanow, Alexandra; Leitner, Michael G; Thallmair, Veronika; Halaszovich, Christian R; Oliver, Dominik

    2015-01-01

    The activity of many proteins depends on the phosphoinositide (PI) content of the membrane. E.g., dynamic changes of the concentration of PI(4,5)P2 are cellular signals that regulate ion channels. The susceptibility of a channel to such dynamics depends on its affinity for PI(4,5)P2. Yet, measuring affinities for endogenous PIs has not been possible directly, but has relied largely on the response to soluble analogs, which may not quantitatively reflect binding to native lipids. Voltage-sensitive phosphatases (VSPs) turn over PI(4,5)P2 to PI(4)P when activated by depolarization. In combination with voltage-clamp electrophysiology VSPs are useful tools for rapid and reversible depletion of PI(4,5)P2. Because cellular PI(4,5)P2 is resynthesized rapidly, steady state PI(4,5)P2 changes with the degree of VSP activation and thus depends on membrane potential. Here we show that titration of endogenous PI(4,5)P2 with Ci-VSP allows for the quantification of relative PI(4,5)P2 affinities of ion channels. The sensitivity of inward rectifier and voltage-gated K(+) channels to Ci-VSP allowed for comparison of PI(4,5)P2 affinities within and across channel subfamilies and detected changes of affinity in mutant channels. The results also reveal that VSPs are useful only for PI effectors with high binding specificity among PI isoforms, because PI(4,5)P2 depletion occurs at constant overall PI level. Thus, Kir6.2, a channel activated by PI(4,5)P2 and PI(4)P was insensitive to VSP. Surprisingly, despite comparable PI(4,5)P2 affinity as determined by Ci-VSP, the Kv7 and Kir channel families strongly differed in their sensitivity to receptor-mediated depletion of PI(4,5)P2. While Kv7 members were highly sensitive to activation of PLC by Gq-coupled receptors, Kir channels were insensitive even when PI(4,5)P2 affinity was lowered by mutation. We hypothesize that different channels may be associated with distinct pools of PI(4,5)P2 that differ in their accessibility to PLC and VSPs.

  12. P2X4 receptors (P2X4Rs represent a novel target for the development of drugs to prevent and/or treat alcohol use disorders

    Directory of Open Access Journals (Sweden)

    Kelle M. Franklin

    2014-06-01

    Full Text Available Alcohol use disorders (AUDs have a staggering socioeconomic impact. Few therapeutic options are available, and they are largely inadequate. These shortcomings highlight the urgent need to develop effective medications to prevent and/or treat AUDs. A critical barrier is the lack of information regarding the molecular target(s by which ethanol (EtOH exerts its pharmacological activity. This review highlights findings implicating P2X4 receptors (P2X4Rs as a target for the development of therapeutics to treat AUDs and discusses the use of ivermectin (IVM as a potential clinical tool for treatment of AUDs. P2XRs are a family of ligand-gated ion channels activated by extracellular ATP. Of the P2XR subtypes, P2X4Rs are expressed the most abundantly in the CNS. Converging evidence suggests that P2X4Rs are involved in the development and progression of AUDs. First, in vitro studies report that pharmacologically relevant EtOH concentrations can negatively modulate ATP-activated currents. Second, P2X4Rs in the mesocorticolimbic dopamine system are thought to play a role in synaptic plasticity and are located ideally to modulate brain reward systems. Third, alcohol-preferring (P rats have lower functional expression of the p2rx4 gene than alcohol-non-preferring (NP rats suggesting an inverse relationship between alcohol intake and P2X4R expression. Similarly, whole brain p2rx4 expression has been shown to relate inversely to innate 24 hr alcohol preference across 28 strains of rats. Fourth, mice lacking the p2rx4 gene drink more EtOH than wildtype controls. Fifth, IVM, a positive modulator of P2X4Rs, antagonizes EtOH-mediated inhibition of P2X4Rs in vitro and reduces EtOH intake and preference in vivo. These findings suggest that P2X4Rs contribute to EtOH intake. The present review summarizes recent findings focusing on the P2X4R as a molecular target of EtOH action, its role in EtOH drinking behavior and modulation of its activity by IVM as a potential

  13. Homodimeric anoctamin-1, but not homodimeric anoctamin-6, is activa