74 research outputs found

    Microparticles: Role in Haemostasis and Venous Thromboembolism

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    Prelaunch optical characterization of the Laser Geodynamic Satellite (LAGEOS 2)

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    The optical range correction (the distance between the apparent retroreflective skin of the satellite and the center of mass) of the LAGEOS 2 was determined using computer analysis of theoretical and experimentally measured far field diffraction patterns, and with short pulse lasers using both streak camera-based range receivers and more conventional PMT-based range receivers. The three measurement techniques yielded range correction values from 248 to 253 millimeters dependent on laser wavelength, pulsewidth, and polarization, location of the receiver in the far field diffraction pattern and detection technique (peak, half maximum, centroid, or constant fraction). The Lidar cross section of LAGEOS 2 was measured at 4 to 10 million square meters, comparable to the LAGEOS 1

    Moving from Intention to Impact: Funding Racial Equity to Win

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    This joint PolicyLink-Bridgespan analysis says funders are a key part of the racial equity ecosystem: to benefit the entire nation they should both be transparent in reporting where grants go and fund what movement leaders say is needed to achieve enduring change

    Tax Evasion, Tax Avoidance and Tax Planning in Australia: The participation in mass-marketed tax avoidance schemes in the Pilbara region of Western Australia in the 1990s

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    This paper will examine the development of mass-marketed tax avoidance schemes in Australia. It will consider changes in approach to tax avoidance from the ‘bottom of the harbour’ schemes of the 1960s and 1970s to the mass-marketed tax avoidance schemes of the 1990s. It will examine the changing structure of tax avoidance from individually crafted tax avoidance structures designed by accountants and lawyers used by high wealth individuals to mass produced structures targeted at highly paid, and therefore highly taxed, blue collar workers in Australia’s mining industry in the 1990s. In the latter half of the twentieth century ‘unacceptable’ tax planning went from highly expensive, individually ‘tailor made’ structures afforded and used only by the very wealthy, to inexpensive replicated structures marketed to skilled and unskilled tradespeople and labourers. By 1998 over 42 000 Australian taxpayers were engaged in tax avoidance schemes with the highest proportion focussed in the mining regions of Western Australia. In the remote and inhospitable mining community of Pannawonica, which has one of the highest paid workforces in Australia, the Australian Taxation Office identified that as many as one in five taxpayers were engaged in a mass-marketed tax avoidance scheme. The paper will identify the causes of these changes, including the advent of the computerised information technology which permitted ‘mass production’ of business structures designed to exploit business incentives in the Australian taxation system in the 1990s. It will also set these developments within the broader context of the tax compliance culture prevailing in Australia and overseas during this period

    Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine

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    [This corrects the article DOI: 10.1186/s13054-016-1208-6.]

    Microparticles in health and disease

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    Microparticles (MPs) are small fragments of membrane-bound cytoplasm that are shed from the surface of an activated or apoptotic cell. Recently, their function as vectors of transcellular exchange of biologic information, in addition to better described forms of intercellular communication such as growth factors, cytokines, and chemokines, has become well recognized. Circulating levels of MPs are thought to reflect a balance between cell stimulation, proliferation, and death. The production of MPs is thought to predominately occur by vesiculation or blebbing of the cell membrane. The mechanisms governing the remodeling of the plasma membrane are complex, involving cytoskeletal changes and a shift from normal phospholipid asymmetry. Increased intracellular calcium subsequent to cell activation leads to intracellular increases in several proteins including gelsolin and calpain, as well as the activity of enzymes such as translocase, floppase, and scramblase, which play important roles in the homeostasis of the cell membrane. The membrane vesiculation and phospholipids asymmetry leading to the production of MPs occurs by the complex interplay of the proteins involved. There are several clinical conditions associated with elevated MPs, and most are also associated with an increased risk of thrombosis. Apart from cardiovascular disease and venous thromboembolism, MPs are also elevated in solid tumors with metastatic disease. The measurement of MPs is being regarded as a potential biomarker, given the range of conditions in which they are elevated and the association with prothrombotic states. The utility of measuring MPs as a diagnostic and prognostic marker is currently a subject of intense investigation. The further development of the various methods for the detection and measurement of MPs and prospective clinical trials establishing the utility of such tests will be critical prior to the routine measurement of MPs in the diagnostic laboratory

    Acute supplementation with eicosapentaenoic acid reduces platelet microparticle activity in healthy subjects

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    Background: Dietary supplementation with omega-3 fatty acids has been associated with reduced incidence in thrombotic events. In addition, administration of n-3 polyunsaturated fatty acids (PUFAs) has been shown to rectify elevated platelet microparticle (MP) number and procoagulant activity in post myocardial infarction patients. However, it is unknown whether supplementation can alter these parameters in healthy individuals and if such effects are immediate or require long-term supplementation. We have previously demonstrated a gender-specific effect of LCn-3PUFA supplementation on platelet aggregation in healthy human subjects. Here we extend these findings to include the acute effects of supplementation with EPA- or DHA-rich oils on circulating MP levels and activity in healthy subjects. Design: A placebo-controlled trial was conducted in healthy males and females (n=30). MP activity, MP levels and platelet aggregation were measured at 0 and 24 h postsupplementation with either a placebo or EPA- or DHA-rich oil. Results: Both EPA and DHA effectively reduced platelet aggregation at 24 h postsupplementation relative to placebo (−13.3%, P=.006 and −11.9%, P=.016, respectively), but only EPA reduced MP activity (−19.4%, P=.003). When grouped by gender, males showed a similar reduction in both platelet aggregation and MP activity (−20.5%, P=.008; −22%, P=.008) following EPA, while females showed significantly reduced platelet aggregation (−13.7%, P=.04) but not MP activity after DHA only. Conclusion: EPA and DHA exert gender-dependent effects on platelet aggregation and platelet MP activity, but not on MP levels. With respect to thrombotic disease risk, males may benefit more from EPA supplementation

    Variable plasma levels of Factor V Leiden correlate with circulating platelet microparticles in carriers of Factor V Leiden

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    Introduction: Inheritance of Factor V Leiden (FVL) is associated with an increased but variable level of risk for thrombosis. We have previously shown that FVL heterozygotes have elevated levels of circulating pro-coagulant microparticles (MP). Here we sought to determine if these subjects differed in their plasma levels of FVL and if this was related to MP concentrations and/or history of thrombosis. Materials and Methods: The Hemoclot Quanti. V-L clotting assay was used to specifically measure FVL in plasma samples from 44 known carriers (12 M, 32 F; aged 46 ± 13 years). Circulating MP were quantified by flow cytometry using fluorochrome conjugated antibodies to platelet (CD41a), leukocyte (CD45), and endothelial (CD62e) surface markers, and MP prothrombinase activity was determined by ELISA. Results: The cohort was found to have a mean FVL of 49.5 ± 5.6% and this was positively correlated to the total number of circulating CD41a + MP (R = 0.31, p = 0.03) but not to other MP subsets or to MP prothrombinase activity. The amount of FVL relative to normal factor V (FVL/FV clotting ratio) was calculated and found to be highly variable, ranging from 0.37 to 0.69, and significantly correlated with a history of thrombosis (n = 14; p = 0.04). Conclusions: This is the first study to investigate the relationship between varying levels of FVL and plasma derived MP. These results are consistent with our previous findings of an increase in MP levels in carriers of FVL as compared to controls, and suggest a role for FVL/FV ratio in predicting risk of thrombosis in carriers of FVL
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