38 research outputs found

    Platelet HIF-2α promotes thrombogenicity through PAI-1 synthesis and extracellular vesicle release

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    Oxygen-compromised environments, such as high altitude, are associated with platelet hyperactivity. Platelets confined within the relatively impervious core of an aggregate/thrombus have restricted access to oxygen, yet they continue to perform energy-intensive procoagulant activities that sustain the thrombus. Studying platelet signaling under hypoxia is, therefore, critical to our understanding of the mechanistic basis of thrombus stability. We report here that hypoxia-inducible factor (HIF)-2α is translated from pre-existing mRNA and stabilized against proteolytic degradation in enucleate platelets exposed to hypoxia. Hypoxic stress, too, stimulates platelets to synthesize plasminogen-activator inhibitor-1 (PAI-1) and shed extracellular vesicles, both of which potentially contribute to the prothrombotic phenotype associated with hypoxia. Stabilization of HIF-α by administering hypoxia-mimetics to mice accelerates thrombus formation in mesenteric arterioles. In agreement, platelets from patients with chronic obstructive pulmonary disease and high altitude residents exhibiting thrombogenic attributes have abundant expression of HIF-2α and PAI- 1. Thus, targeting platelet hypoxia signaling could be an effective anti-thrombotic strategy

    Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

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    Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

    Antiinflammatory Therapy with Canakinumab for Atherosclerotic Disease

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    Background: Experimental and clinical data suggest that reducing inflammation without affecting lipid levels may reduce the risk of cardiovascular disease. Yet, the inflammatory hypothesis of atherothrombosis has remained unproved. Methods: We conducted a randomized, double-blind trial of canakinumab, a therapeutic monoclonal antibody targeting interleukin-1β, involving 10,061 patients with previous myocardial infarction and a high-sensitivity C-reactive protein level of 2 mg or more per liter. The trial compared three doses of canakinumab (50 mg, 150 mg, and 300 mg, administered subcutaneously every 3 months) with placebo. The primary efficacy end point was nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death. RESULTS: At 48 months, the median reduction from baseline in the high-sensitivity C-reactive protein level was 26 percentage points greater in the group that received the 50-mg dose of canakinumab, 37 percentage points greater in the 150-mg group, and 41 percentage points greater in the 300-mg group than in the placebo group. Canakinumab did not reduce lipid levels from baseline. At a median follow-up of 3.7 years, the incidence rate for the primary end point was 4.50 events per 100 person-years in the placebo group, 4.11 events per 100 person-years in the 50-mg group, 3.86 events per 100 person-years in the 150-mg group, and 3.90 events per 100 person-years in the 300-mg group. The hazard ratios as compared with placebo were as follows: in the 50-mg group, 0.93 (95% confidence interval [CI], 0.80 to 1.07; P = 0.30); in the 150-mg group, 0.85 (95% CI, 0.74 to 0.98; P = 0.021); and in the 300-mg group, 0.86 (95% CI, 0.75 to 0.99; P = 0.031). The 150-mg dose, but not the other doses, met the prespecified multiplicity-adjusted threshold for statistical significance for the primary end point and the secondary end point that additionally included hospitalization for unstable angina that led to urgent revascularization (hazard ratio vs. placebo, 0.83; 95% CI, 0.73 to 0.95; P = 0.005). Canakinumab was associated with a higher incidence of fatal infection than was placebo. There was no significant difference in all-cause mortality (hazard ratio for all canakinumab doses vs. placebo, 0.94; 95% CI, 0.83 to 1.06; P = 0.31). Conclusions: Antiinflammatory therapy targeting the interleukin-1β innate immunity pathway with canakinumab at a dose of 150 mg every 3 months led to a significantly lower rate of recurrent cardiovascular events than placebo, independent of lipid-level lowering. (Funded by Novartis; CANTOS ClinicalTrials.gov number, NCT01327846.

    Plant species diversity for sustainable management of crop pests and diseases in agroecosystems: a review

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    Improving trade visibility and fidelity in defense requirements portfolio management

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    Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, School of Engineering, Institute for Data, Systems, and Society, System Design and Management Program, 2014.Cataloged from PDF version of thesis.Includes bibliographical references (pages 77-80).In 2003, the Department of Defense (DoD) requirements process migrated from a bottom-up, threat-based force-planning method to a capability-based, top-down approach with the introduction of the Joint Capabilities Integration and Development System (JCIDS). The primary objective of the JCIDS process is to ensure the capabilities required by the joint warfighter are identified, assessed, validated, and prioritized in a transparent process that allows for a balanced and informed decision. Although JCIDS continues to evolve, criticisms remain: solution development and delivery are not timely; the process is complex; and it lacks mechanisms to focus the review across portfolios; to name a few. It is imperative to address these fundamental issues as the DoD is now forced to operate within a severely constrained fiscal environment - the DoD must gain better insight and visibility across its defense requirements portfolio. This thesis seeks to address these issues through the application of Systems Engineering techniques, specifically an Enterprise Strategic Analysis and Semantic Architecture review, to the JCIDS process. The Enterprise Strategic Analysis reveals the critical stakeholder interactions as well as nuances of the landscape in which JCIDS functions. This is followed by a detailed Semantic Architecture review of sample documents within the JCIDS process to inform a knowledge base. The result of these steps is a formative ontology which reveals basic relationships and patterns with the ability to assist decision makers manage the complexity inherent in the management of joint capabilities.by L. Najeeb Ahmed.S.M. in Engineering and Managemen

    Eating behavior in frontotemporal dementia

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    Objective: To contrast the relationships of hormonal eating peptides and hypothalamic volumes to eating behavior and metabolic changes (body mass index [BMI]) in behavioral variant frontotemporal dementia (bvFTD) and semantic variant primary progressive aphasia (svPPA). Methods: Seventy-five patients with dementia (19 bvFTD, 26 svPPA, and 30 Alzheimer disease dementia) and 23 controls underwent fasting blood analyses of leptin, ghrelin, cholecystokinin, peptide tyrosine tyrosine (PYY), and agouti-related peptide (AgRP) levels. On brain MRI anterior, posterior, and total hypothalamic volumes were measured. Relationships between endocrine measures, hypothalamic volumes, eating behaviors, and BMI were investigated. Results: Levels of AgRP were higher in patients with bvFTD (69 6 89 pg/mL) and svPPA (62 6 81 pg/mL) compared with controls (23 6 19 pg/mL, p , 0.01). No differences were found for leptin, oxytocin, cholecystokinin, ghrelin, and PYY levels. Patients with bvFTD and svPPA had higher scores on questionnaires measuring eating behaviors. Atrophy of the posterior and total hypothalamus was observed in the bvFTD group only. Linear regression modeling revealed that leptin and AgRP levels predicted BMI. Conclusion: Eating abnormalities are multifactorial in FTD. In bvFTD, they are in part related to hypothalamic degeneration, with potential disintegration of the network connections between the hypothalamus and orbitofrontal cortex/reward pathways. In svPPA, although hypothalamic volumes are preserved, this group experiences elevated AgRP levels similar to bvFTD, which predicts BMI in both groups. This finding highlights the potential key role of AgRP in eating and metabolic changes and provides a potential target for treatment to modify disease progression

    You use! I use! We use! Questioning the orthodoxy of 1:1 computing in primary schools

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    The current orthodoxy regarding computer use in schools appears to be that 1:1 computing, i.e. each child owns or has sole access to a computing device, is the most efficacious way to achieve a range of desirable educational outcomes including individualised learning, collaborative environments or constructivist pedagogies. This article challenges this notion suggesting instead that 1:2 computing is an appropriate means of achieving such aims in Primary School. It further suggests that 1:2 computing is preferable to 1:1 computing to achieve a balance between productivity, student engagement, social activity and individualised learning. This article draws on data collected during the 2009 school year from four, Year 7 Classrooms (11-13 year old students) who had varied patterns of access to netbook computers. Detailed information was collected from two pieces of software installed in each computer. Data were analysed through an Activity Theory conceptual and methodological lens. Recommendations from this research will assist school leaders make informed decisions regarding 1:1 and 1:2 computing
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