949 resultados para 15 term
Resumo:
The requirement for cooperative interactions between multiple synaptic inputs in the induction of long-term potentiation (LTP) and long-term depression (LTD) has been tested at Schaffer collateral synapses with paired recordings from monosynaptically coupled CA3-CA1 cell pairs in rat hippocampal slice cultures. Tetanization of single presynaptic neurons at 50 Hz (repeated 5-7 times for 300-500 ms each) induced only a transient potentiation (< 3 min) of excitatory postsynaptic potentials (EPSPs). Persistent potentiation (> 15 min) was induced only when single presynaptic action potentials were synchronously paired with directly induced postsynaptic depolarizing pulses (repeated 50-100 times). Tetanus-induced potentiation of extracellularly evoked EPSPs lasting > 4 min could only be obtained if the EPSP was > 4 mV. Because unitary EPSP amplitudes average approximately 1 mV, we conclude that high-frequency discharge must occur synchronously] in 4-5 CA3 cells for LTP to be induced in a common postsynaptic CA1 cell. Asynchronous pairing of presynaptic action potentials with postsynaptic depolarizing current pulses (preceding each EPSP by 800 ms) depressed both naive and previously potentiated unitary EPSPs. Likewise, homosynaptic LTD of unitary EPSPs was induced when the presynaptic cell was tetanized at 3 Hz for 3 min, regardless of their amplitude (0.3-3.2 mV). Homosynaptic LTD of extracellularly evoked Schaffer collateral EPSPs < 4 mV could be induced if no inhibitory postsynaptic potential was apparent, but was prevented by eliciting a large inhibitory postsynaptic potential or by injection of hyperpolarizing current in the postsynaptic cell. We conclude that cooperative interactions among multiple excitatory inputs are not required for induction of homosynaptic LTD of unitary EPSPs.
Resumo:
Both serine/threonine and tyrosine phosphorylation of receptor proteins have been implicated in the process of long-term potentiation (LTP), but there has been no direct demonstration of a change in receptor phosphorylation after LTP induction. We show that, after induction of LTP in the dentate gyrus of anesthetized adult rats, there is an increase in the tyrosine phosphorylation of the 2B subunit of the N-methyl-D-aspartate (NMDA) receptor (NR2B), as well as several other unidentified proteins. Tyrosine phosphorylation of NR2B was measured in two ways: binding of antiphosphotyrosine antibodies (PY20) to glycoprotein(s) of 180 kDa (GP180) purified on Con A-Sepharose and binding of anti-NR2B antibodies to tyrosine-phosphorylated proteins purified on PY20-agarose. Three hours after LTP induction, anti-NR2B binding to tyrosine phosphorylated proteins, expressed as a ratio of tetanized to control dentate (Tet/Con), was 2.21 +/- 0.50 and PY20 binding to GP180 was 1.68 +/- 0.16. This increase in the number of tyrosine phosphorylated NR2B subunits occurred without a change in the total number of NR2B subunits. When the induction of LTP was blocked by pretreatment of the animal with the NMDA receptor antagonist MK801, the increase in PY20 binding to GP180 was also blocked (Tet/Con = 1.09 +/- 0.26). The increased PY20 binding to GP180 was also apparent 15 min after LTP induction (Tet/Con = 1.41 +/- 0.16) but not detectable 5 min after LTP induction (Tet/Con = 1.01 +/- 0.19). These results suggest that tyrosine phosphorylation of the NMDA receptor contributes to the maintenance of LTP.
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The primate temporal cortex has been demonstrated to play an important role in visual memory and pattern recognition. It is of particular interest to investigate whether activity-dependent modification of synaptic efficacy, a presumptive mechanism for learning and memory, is present in this cortical region. Here we address this issue by examining the induction of synaptic plasticity in surgically resected human inferior and middle temporal cortex. The results show that synaptic strength in the human temporal cortex could undergo bidirectional modifications, depending on the pattern of conditioning stimulation. High frequency stimulation (100 or 40 Hz) in layer IV induced long-term potentiation (LTP) of both intracellular excitatory postsynaptic potentials and evoked field potentials in layers II/III. The LTP induced by 100 Hz tetanus was blocked by 50-100 microM DL-2-amino-5-phosphonovaleric acid, suggesting that N-methyl-D-aspartate receptors were responsible for its induction. Long-term depression (LTD) was elicited by prolonged low frequency stimulation (1 Hz, 15 min). It was reduced, but not completely blocked, by DL-2-amino-5-phosphonovaleric acid, implying that some other mechanisms in addition to N-methyl-DL-aspartate receptors were involved in LTD induction. LTD was input-specific, i.e., low frequency stimulation of one pathway produced LTD of synaptic transmission in that pathway only. Finally, the LTP and LTD could reverse each other, suggesting that they can act cooperatively to modify the functional state of cortical network. These results suggest that LTP and LTD are possible mechanisms for the visual memory and pattern recognition functions performed in the human temporal cortex.
Resumo:
The injection of recombinant erythropoietin (Epo) is now widely used for long-term treatment of anemia associated with chronic renal failure, cancer, and human immunodeficiency virus infections. The ability to deliver this hormone by gene therapy rather than by repeated injections could provide substantial clinical and economic benefits. As a preliminary approach, we investigated in rats the expression and biological effects of transplanting autologous vascular smooth muscle cells transduced with a retroviral vector encoding rat Epo cDNA. Vector-derived Epo secretion caused increases in reticulocytes, with peak levels of 7.8-9.6% around day 10 after implantation. The initial elevation in reticulocytes was followed by clinically significant increases in hematocrit and hemoglobin for up to 11 weeks. Ten control and treated animals showed mean hematocrits of 44.9 +/- 0.4% and 58.7 +/- 3.1%, respectively (P < 0.001), and hemoglobin values of 15.6 +/- 0.1 g/dl and 19.8 +/- 0.9 g/dl, respectively (P < 0.001). There were no significant differences between control and treated animals in the number of white blood cells and platelets. Kidney and to a lesser extent liver are specific organs that synthesize Epo in response to tissue oxygenation. In the treated animals, endogenous Epo mRNA was largely down regulated in kidney and absent from liver. These results indicate that vascular smooth muscle cells can be genetically modified to provide treatment of anemias due to Epo deficiency and suggest that this cell type may be targeted in the treatment of other diseases requiring systemic therapeutic protein delivery.
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Background: The harmonization of European health systems brings with it a need for tools to allow the standardized collection of information about medical care. A common coding system and standards for the description of services are needed to allow local data to be incorporated into evidence-informed policy, and to permit equity and mobility to be assessed. The aim of this project has been to design such a classification and a related tool for the coding of services for Long Term Care (DESDE-LTC), based on the European Service Mapping Schedule (ESMS). Methods: The development of DESDE-LTC followed an iterative process using nominal groups in 6 European countries. 54 researchers and stakeholders in health and social services contributed to this process. In order to classify services, we use the minimal organization unit or “Basic Stable Input of Care” (BSIC), coded by its principal function or “Main Type of Care” (MTC). The evaluation of the tool included an analysis of feasibility, consistency, ontology, inter-rater reliability, Boolean Factor Analysis, and a preliminary impact analysis (screening, scoping and appraisal). Results: DESDE-LTC includes an alpha-numerical coding system, a glossary and an assessment instrument for mapping and counting LTC. It shows high feasibility, consistency, inter-rater reliability and face, content and construct validity. DESDE-LTC is ontologically consistent. It is regarded by experts as useful and relevant for evidence-informed decision making. Conclusion: DESDE-LTC contributes to establishing a common terminology, taxonomy and coding of LTC services in a European context, and a standard procedure for data collection and international comparison.
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An ambitious, comprehensive and high-standard trade and investment agreement between the European Union and the United States is feasible, but a key concern is whether the transatlantic trade partners will succeed in creating a meaningful agreement within the tight timeline of the Transatlantic Trade and Investment Partnership (TTIP) negotiations. The target of a ratified pact before a new European Commission takes office in November 2014 is an objective that is likely to conflict with the level of ambition on the substance. Regulatory congruence would require the unilateral and unconditional recognition by the TTIP partners of each other’s standards, procedures and conformity assessment tests. The way forward is to create a ‘living’ (or progressive commitment) agreement on regulatory cooperation with a horizontal template for coherence and conformity assessment and a detailed monitoring mechanism, with implementation starting immediately for a few selected sectors. Regulatory harmonisation under TTIP may not lead to emerging markets automatically upgrading to the higher TTIP standards. Domestic priorities and the high demand from a rising price-sensitive group of consumers will likely result in a dual regulatory regime in emerging markets in the medium-term.
Resumo:
Following several years of political turmoil triggered by constitutional reform (a shift from a presidential to a semi-presidential system) and electoral reshuffles (parliamentary elections in 2012; presidential elections in 2013), the political situation in Georgia has stabilised: key posts in the country are now in the hands of democratically elected members of the Geor-gian Dream coalition. Despite its mosaic-like structure and internaltensions, Georgian Dream remains strong and enjoys high levels of public support. This puts it in good stead to play a central role in Georgian politics in the foreseeable future, including securing victory in the local government elections scheduled for June. However, local billionaire Bidzina Ivanishvili does not currently hold a political office - despite the fact that he is the founder, sponsor and undisputed leader of the coalition, as well as former prime minister and the most popular public figure in Georgia (besides Patriarch Ilia II). This raises several questions, for example: Who is really at the helm of the Georgian state? What is the lon-g-term vision of the current government? The past achievements of the politically heterogeneo-us Georgian Dream - dominated by Mr Ivanishvili - offer little help in answering these questions. In addition to a series of challenges on the domestic front, the new Georgian leadership is also facing strategic geopolitical challenges, compounded by the current conflict in Ukraine. These include the future of Georgia’s relations with the West (including the process of EU and NATO integration) and with Russia (in response to repeated attempts to re-integrate the post-Soviet republics). The scale and dynamism of the changes in both the geopolitical order in the post-Soviet region and in the relations between Russia and the West are causing further questions to be raised about their impact on the position of the Georgian political elite and about their consequences for the entire country.
Resumo:
The October 2014 agreement on gas supplies between Russia, Ukraine and the European Union did not resolve the Ukraine-Russia conflict over gas. The differences between parties in terms of objectives, growing mistrust and legacy issues make it unlikely that a long-term stable arrangement will be achieved without further escalation. Without EU pressure and support, Ukraine is likely to enter a new unfavourable gas arrangement with Russia, which could have repercussions beyond the energy sector. Key highlights: To reduce prices and increase the security of imports, the EU as a bloc should redefine its gas relationship with Russia and Ukraine and overcome the diverging interests of EU member states on second-order issues. Implementation of a joint strategy rests on enforcement of EU competition and gas market rules, a strengthened role for the Energy Community and the establishment of a market-based instrument for supply security. For Ukraine, the EU should serve as an anchor for comprehensive gas sector reform. Contingent on Ukraine’s reform efforts, EU financial and technical assistance, the enabling of reverse flows from the EU to Ukraine and pressure on Gazprom, should eventually enable Ukraine to obtain a sustainable gas-supply contract with Russia. This should make a sustainable and mutually beneficial Russia-Ukraine-EU gas relationship possible. However, during the transition, the EU should be prepared for possible frictions.
Resumo:
Long term care (LTC) is both costly and of increasing concern as baby boomers age and more people live longer with chronic conditions. Today, people receive formal and informal LTC supports in homes, nursing homes, and alternative settings around the world. Where people live and the way LTC is delivered has an important impact on whether person’s receiving care thrive as they age. This paper is about how different LTC environments in the U.S. and The Netherlands foster or impede social connectivity, suggesting that quality of life will be impeded and types of social death, or disconnection from social life, more often the result in environments that limit choice and self determination, limit access to privacy and social connection, and limit access to reciprocal exchanges, a key component of participating in relationships typical of the concept of “the gift” introduced by anthropologist Marcel Mauss in 1954. Building on ethnographic data from a 15-month study of LTC in The Netherlands and a review of staffing practices in LTC environments in the U.S. and The Netherlands, I will explore concepts of reciprocity and social connectivity impacted by various LTC environments in two countries known to experiment with different models of care. This research builds on social constructivist notions of death and dying explored throughout this edited volume and adds to this effort examination of social death in anthropological perspective.
Resumo:
From the Introduction. In 2012, China approached the countries of Central-Eastern Europe (CEE) with a proposal concerning regional cooperation in the ‘16+1’ formula. According to Chinese analysts, the rationale behind this breakthrough decision was Beijing’s acknowledgment of the growing importance of the region’s states within the European Union as well as a partial elimination of the ideological differences which had hamstrung cooperation in previous years. It seems that the eurozone crisis may be perceived as the reason for the CEE states’ increased interest in developing their cooperation with China. These circumstances have opened a ‘window of opportunity’ which Beijing has decided to exploit to create a kind of bridgehead in the region which it could later use in its further economic expansion in Europe. Apart from opening the CEE region up for investments, the ‘16+1’ format was intended to facilitate the shaping of relations between China and the EU and to become a tool in building a positive image for China. Chinese experts agree that after three years of functioning, the ‘16+1’ regional cooperation format has helped Beijing achieve its goals only to a limited extent. The major obstacles have included: the immense diversification of the region, barriers related to EU law, insufficient expertise on the part of Chinese companies, the asymmetry of economic needs on both sides, and no willingness within the region itself to develop cooperation. Regardless of the limited effectiveness of activities carried out so far, China has continued its ‘16+1’ initiative. This continuation and the progressing institutionalisation of cooperation in the ‘16+1’ format have often seemed superficial. China has been using this multi-party formula to improve its long-term bilateral relations with selected states in the region and thereby to create a basis for Beijing’s political and economic presence in Central-Eastern Europe.
Resumo:
Throughout the twenty-first century the United States (U.S.) has attempted to balance its traditional national security interests, whilst also seeking to promote the long-term transformation of the Middle East and North Africa (MENA) towards democracy based on liberal values. With the September 11, 2001 terrorist attacks providing a catalyst for policy change, the U.S. has moved away from its twentieth-century policy of pursuing a regional status quo and instinctively balking at political change. Yet, the U.S. has not abandoned its reliance on autocratic regimes that cooperate on more immediate national security interests such as counter-terrorism, counter-proliferation, and the free-flow energy sources into the global market. Rather, U.S. democracy promotion in the MENA has become incremental by design and is characterized by its gradualist and often-collaborative nature. U.S. foreign policy in the MENA is, therefore, depicted by a cautious evolutionary stance rather than supporting revolutionary shifts in power.
Resumo:
The Russian economy grew rapidly between 2000 and 2007, but growth decelerated after the 2008-09 global financial crisis, and since mid-2014 Russia has moved into recession. A number of short-term factors have caused recession: lower oil prices, the conflict with Ukraine, European Union and United States sanctions against Russia and Russian counter-sanctions. However Russia's negative output trends have deeper structural and institutional roots. They can be tracked back about a decade to when previous market-reform policies started to be reversed in favour of dirigisme, leading to further deterioration of the business and investment climate. • Russia must address its short-term problems, but in the medium-to-long term it must deal with its fundamental structural and institutional disadvantages: oil and commodity dependence and an unfriendly business and investment climate underpinned by poor governance. Compared to many other commodity producers, Russia is better placed to diversify its economy, mostly due to its excellent human capital. Ruble depreciation makes this task easier
Resumo:
The Grand Duchy of Luxembourg held the reins of the EU Council presidency between 1 July and 31 December 2015. This was the 12th time that the second-smallest and the richest EU member state1 held the rotating Council presidency. As one of the founding members of the EU, Luxembourg has sound experience to bring to this role. It was, however, their first presidency since the entry into force of the Lisbon Treaty and its introduction of the trio presidency format, this time including Italy and Latvia. Under the slogan ‘A Union for the Citizens’, Luxembourg had the task of concluding certain major dossiers before the end of the trio’s term and was able to contribute to its overarching agenda, especially regarding the priorities of financial stability, growth stimulation and the digital agenda.
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In a communication to the Parliament and the Council entitled “Towards a modern, more European copyright framework” and dated 9 December 2015,1 the European Commission confirmed its intention to progressively remove the main obstacles to the functioning of the Digital Single Market for copyrighted works. The first step of this long-term plan, which was first announced in Juncker’s Political Guidelines2 and the Communication on “A Digital Single Market strategy for Europe”,3 is a proposal for a regulation aimed at ensuring the so-called ‘cross-border portability’ of online services giving access to content such as music, games, films and sporting events.4 In a nutshell, the proposed regulation seeks to enable consumers with legal access to such online content services in their country of residence to use the same services also when they are in another member state for a limited period of time. On the one hand, this legislative proposal has the full potential to resolve the (limited) issue of portability, which stems from the national dimension of copyright and the persisting territorial licensing and distribution of copyright content.5 On the other hand, as this commentary shows, the ambiguity of certain important provisions in the proposed regulation might affect its scope and effectiveness and contribute to the erosion of the principle of copyright territoriality.
Resumo:
The EU is in uncharted waters when it comes to negotiating the UK’s exit from the Union. Creative and flexible thinking will be required from all parties if an orderly departure is to be managed. The alternative is a fractious, mutually damaging and disorderly Brexit. This commentary argues for a short-term, time-limited agreement to stabilise the EU-UK relationship and to allow breathing space to develop the terms of a long-term strategic partnership.