194 research outputs found
In vitro and in vivo studies of the thiol:disulphide oxidoreductase ResA from Bacillus subtilis and Streptomyces coelicolor
Marked by Exile: Trauma and the Grand DĂ©rangement
This essay explores the possibilities and pitfalls of viewing the grand dĂ©rangement through the lens of the emerging field of trauma studies. Drawing on insights from disciplines as diverse as psychology, social work, biology, and neuroscience, trauma studies has been applied to history only haltingly, and most often in relation to modern events for which first-person accounts are plentifulâthe Holocaust, for example. Although early modern people such as eighteenth-century Acadians endured violence and displacement, the limited number and nature of sources that reflect personal experiences makes the application of trauma studies precarious. Recent scholarship on contemporary refugee crises, however, suggests the potential relevance of trauma studies for understanding the impact of the grand dĂ©rangement on the Acadian exiles who endured it. With special attention to the influence of divergent âecologies of displacementâ on the grand dĂ©rangementâs victims, this essay argues that when carefully delimited, trauma studies can yield a richer portrait of the Acadian diasporaâs impact on an individual scale.Cette Ă©tude explore les possibilitĂ©s et les risques que comporte la perception du Grand dĂ©rangement dans lâoptique du domaine Ă©mergent des Ă©tudes de traumatismes. Sâappuyant sur les connaissances des disciplines aussi diverses que la psychologie, le travail social, la biologie et la neuroscience, les Ă©tudes de traumatismes dans lâhistoire nâont pourtant Ă©tĂ© mises de lâavant que de façon intermittente. De plus, ces Ă©tudes se rapportent surtout aux situations rĂ©centes pour lesquelles des tĂ©moignages personnels sont nombreux, tels que ceux portant sur lâHolocauste. Bien que les peuples contemporains tels que les Acadiens du dix-huitiĂšme siĂšcle aient subi des actes de violence et des dĂ©placements, le caractĂšre et le nombre restreint des sources dâexpĂ©riences personnelles rendent prĂ©caire la mise en Ćuvre des Ă©tudes sur les traumatismes. Toutefois, lâĂ©rudition rĂ©cente sur la situation critique actuelle des rĂ©fugiĂ©s suggĂšre la pertinence dâĂ©tudier les traumatismes afin de mieux comprendre lâincidence troublante du Grand dĂ©rangement sur les Acadiens exilĂ©s qui lâont subi. La prĂ©sente Ă©tude prĂȘte une attention toute particuliĂšre Ă lâinfluence des diverses âĂ©cologies des dĂ©placementsâ sur les victimes du Grand dĂ©rangement, de sorte Ă soutenir une Ă©tude dĂ©limitĂ©e des traumatismes et esquisser un portrait plus prĂ©cis de lâexpĂ©rience percutante de la diaspora acadienne sur lâindividu
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Using deuterated PAH amendments to validate chemical extraction methods to predict PAH bioavailability in soils
Validating chemical methods to predict bioavailable fractions of polycyclic aromatic hydrocarbons (PAHs) by comparison with accumulation bioassays is problematic. Concentrations accumulated in soil organisms not only depend on the bioavailable fraction but also on contaminant properties. A historically contaminated soil was freshly spiked with deuterated PAHs (dPAHs). dPAHs have a similar fate to their respective undeuterated analogues, so chemical methods that give good indications of bioavailability should extract the fresh more readily available dPAHs and historic more recalcitrant PAHs in similar proportions to those in which they are accumulated in the tissues of test organisms. Cyclodextrin and butanol extractions predicted the bioavailable fraction for earthworms (Eisenia fetida) and plants (Lolium multiflorum) better than the exhaustive extraction. The PAHs accumulated by earthworms had a larger dPAH:PAH ratio than that predicted by chemical methods. The isotope ratio method described here provides an effective way of evaluating other chemical methods to predict bioavailability
Chemoembolization of Hepatocellular Carcinoma with Parasitic Blood Supply from the Inferior Phrenic Artery
Elevated cardiorespiratory fitness and reduced aortic stiffness confer improved cerebral perfusion and memory
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Relative proportions of polycyclic aromatic hydrocarbons differ between accumulation bioassays and chemical methods to predict bioavailability
Chemical methods to predict the bioavailable fraction of organic contaminants are usually validated in the literature by comparison with established bioassays. A soil spiked with polycyclic aromatic hydrocarbons (PAHs) was aged over six months and subjected to butanol, cyclodextrin and tenax extractions as well as an exhaustive extraction to determine total PAH concentrations at several time points. Earthworm (Eisenia fetida) and rye grass root (Lolium multiflorum) accumulation bioassays were conducted in parallel. Butanol extractions gave the best relationship with earthworm accumulation (r2 †0.54, p †0.01); cyclodextrin, butanol and acetoneâhexane extractions all gave good predictions of accumulation in rye grass roots (r2 †0.86, p †0.01). However, the profile of the PAHs extracted by the different chemical methods was significantly different (p < 0.01) to that accumulated in the organisms. Biota accumulated a higher proportion of the heavier 4-ringed PAHs. It is concluded that bioaccumulation is a complex process that cannot be predicted by measuring the bioavailable fraction alone.
The ability of chemical methods to predict PAH accumulation in Eisenia fetida and Lolium multiflorum was hindered by the varied metabolic fate of the different PAHs within the organisms
Some thoughts on silicon and carbon trade-offs in plants
In 1983, Raven suggested that silica could substitute for lignin or cellulose as a structural material in plants, and should be favoured because of its lower energetic costs. He then asked the question why more plants did not use silica for structural support. Raven's idea eventually led to a whole series of investigations into the substitution of silicon for carbon in plants, so-called trade-offs. In this Opinion we offer some, hopefully helpful, thoughts on this research, and we attempt to answer Raven's question. We conclude that more focus on the distribution of silicon and carbon at the cellular level is needed, and that we should be more careful to avoid teleological thinking
The subcoronary Toronto stentless versus supra-annular Perimount stented replacement aortic valve: Early clinical and hemodynamic results of a randomized comparison in 160 patients
BackgroundA stentless valve is expected to be hemodynamically superior to a stented valve. The aim of this study was to compare early postoperative hemodynamic function and clinical events in a randomized, prospective series of 160 stentless and stented biological replacement aortic valves.MethodsWe randomized 160 consecutive patients on 1 surgeonâs list to receive either a Toronto stentless porcine valve (St Jude Medical, Inc, St Paul, Minn) or a Perimount stented bovine pericardial valve (Edwards Lifesciences, Irvine, Calif). Echocardiography was performed at discharge, between 3 and 6 months, and at 1 year after surgery. Statistical analysis was performed by both intention to treat and actual valves implanted.ResultsThe mean labeled size of both designs of valve was 24.7. There were no statistically significant differences in results at any time interval or whether analysis was performed by actual valves implanted or intention to treat. At 3 to 6 months for the Toronto versus the Perimount valve, the effective orifice area was 1.58 versus 1.66 cm2, the mean pressure difference was 7.54 versus 7.42 mm Hg, and the peak velocity was 2.07 versus 2.0.1 m/s. There was no difference in mortality, regression of left ventricular hypertrophy, or complications other than paraprosthetic regurgitation at 12 months or on follow-up for a proportion of the sample to 8 years. The incidence of regurgitation through the valves was similar for Toronto (10%) and Perimount (13.8%) at 1 year, but mild paraprosthetic regurgitation was found in 5 patients with the Perimount valve and none with Toronto valves.ConclusionsThere were no significant differences in hemodynamic function or clinical events between the stented and stentless biological valves chosen for comparison in the early postoperative period or in preliminary follow-up to 5 years
Shortâacting erythropoiesisâstimulating agents for anaemia in predialysis patients
Background The benefits of erythropoiesisâstimulating agents (ESA) for chronic kidney disease (CKD) patients have been previously demonstrated. However, the efficacy and safety of shortâacting epoetins administered at larger doses and reduced frequency as well as of new epoetins and biosimilars remains uncertain. Objectives This review aimed to evaluate the benefits and harms of different routes, frequencies and doses of epoetins (epoetin alpha, epoetin beta and other shortâacting epoetins) for anaemia in adults and children with CKD not receiving dialysis. Search methods We searched the Cochrane Kidney and Transplant Specialised Register to 12 September 2016 through contact with the Information Specialist using search terms relevant to this review. Studies contained in the Specialised Register are identified through search strategies specifically designed for CENTRAL, MEDLINE, and EMBASE; handsearching conference proceedings; and searching the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov. Selection criteria We included randomised control trials (RCTs) comparing different frequencies, routes, doses and types of shortâacting ESAs in CKD patients. Data collection and analysis Two authors independently assessed study eligibility and four authors assessed risk of bias and extracted data. Results were expressed as risk ratio (RR) or risk differences (RD) with 95% confidence intervals (CI) for dichotomous outcomes. For continuous outcomes the mean difference (MD) with 95% confidence intervals (CI) was used. Statistical analyses were performed using the randomâeffects model. Main results We identified 14 RCTs (2616 participants); nine studies were multiâcentre and two studies involved children. The risk of bias was high in most studies; only three studies demonstrated adequate random sequence generation and only two studies were at low risk of bias for allocation concealment. Blinding of participants and personnel was at low risk of bias in one study. Blinding of outcome assessment was judged at low risk in 13 studies as the outcome measures were reported as laboratory results and therefore unlikely to be influenced by blinding. Attrition bias was at low risk of bias in eight studies while selective reporting was at low risk in six included studies. Four interventions were compared: epoetin alpha or beta at different frequencies using the same total dose (six studies); epoetin alpha at the same frequency and different total doses (two studies); epoetin alpha administered intravenously versus subcutaneous administration (one study); epoetin alpha or beta versus other epoetins or biosimilars (five studies). One study compared both different frequencies of epoetin alpha at the same total dose and at the same frequency using different total doses. Data from only 7/14 studies could be included in our metaâanalyses. There were no significant differences in final haemoglobin (Hb) levels when dosing every two weeks was compared with weekly dosing (4 studies, 785 participants: MD â0.20 g/dL, 95% CI â0.33 to â0.07), when four weekly dosing was compared with two weekly dosing (three studies, 671 participants: MD â0.16 g/dL, 95% CI â0.43 to 0.10) or when different total doses were administered at the same frequency (four weekly administration: one study, 144 participants: MD 0.17 g/dL 95% CI â0.19 to 0.53). Five studies evaluated different interventions. One study compared epoetin theta with epoetin alpha and found no significant differences in Hb levels (288 participants: MD â0.02 g/dL, 95% CI â0.25 to 0.21). One study found significantly higher pain scores with subcutaneous epoetin alpha compared with epoetin beta. Two studies (165 participants) compared epoetin delta with epoetin alpha, with no results available since the pharmaceutical company withdrew epoetin delta for commercial reasons. The fifth study comparing the biosimilar HX575 with epoetin alpha was stopped after patients receiving HX575 subcutaneously developed antiâepoetin antibodies and no results were available. Adverse events were poorly reported in all studies and did not differ significantly within comparisons. Mortality was only detailed adequately in four studies and only one study included quality of life data. Authors' conclusions Epoetin alpha given at higher doses for extended intervals (two or four weekly) is nonâinferior to more frequent dosing intervals in maintaining final Hb levels with no significant differences in adverse effects in nonâdialysed CKD patients. However the data are of low methodological quality so that differences in efficacy and safety cannot be excluded. Further large, well designed, RCTs with patientâcentred outcomes are required to assess the safety and efficacy of large doses of the shorter acting ESAs, including biosimilars of epoetin alpha, administered less frequently compared with more frequent administration of smaller doses in children and adults with CKD not on dialysis
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