136 research outputs found

    Geomagnetic Field Behavior at High Latitudes from a Paleomagnetic Record from Eltanin Core 27-21 in the Ross Sea Sector, Antarctica

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    We present a high-resolution paleomagnetic record from 682 discrete samples from Eltanin 27-21 (69.03°S 179.83°E), a 16-meter long piston core recovered in 1968 at a water depth of 3456 meters by the USNS Eltanin as part of Operation Deep Freeze. After removal of a low-coercivity overprint, most samples yield stable characteristic remanent magnetization directions. The downhole variation in the magnetic inclination provides a well-resolved magnetostratigraphy from the Brunhes Chron (0-0.78 Ma), through the Reunion Subchron (2.128-2.148 Ma), and into Chron C2r.2r. The sedimentation rates are sufficiently high that even short-term geomagnetic features, like the Cobb Mountain excursion, are resolved. The record from Eltanin 27-21 provides new insights into the behavior of the geomagnetic field at high latitudes, about which very little is currently known. Using the variability in the inclinations during stable polarity intervals, we estimate that the dispersion in the paleomagnetic pole position over the past ~2 Myr is 30.3°±4.3°, which is significantly greater than observed at low to mid latitude sites. The higher dispersion observed at Eltanin 27-21 is consistent with numerical modeling of the geodynamo. That modeling has shown that polar vortices can develop in the Earth’s core within the tangent cylinder, defined as the cylinder coaxial with the Earth’s rotation axis and tangent to the inner core/outer core boundary. The polar vortices produce vigorous fluid motion in the core, which creates greater geomagnetic field variability above the tangent cylinder at the surface of the Earth. The tangent cylinder intersects the Earth’s surface in the polar regions at 69.6° latitude, which is very close to the latitude of Eltanin 27-21

    Intravenous versus oral iron supplementation for correction of post-transplant anaemia in renal transplant patients

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    Background Post-transplant anaemia remains a common problem after kidney transplantation, with an incidence ranging from nearly 80% at day 0 to about 25% at 1 year. It has been associated with poor graft outcome, and recently has also been shown to be associated with increased mortality. Our transplant unit routinely administers oral iron supplements to renal transplant recipients but this is frequently accompanied by side effects, mainly gastrointestinal intolerance. Intravenous iron is frequently administered to dialysis patients and we sought to investigate this mode of administration in transplant recipients after noticing less anaemia in several patients who had received intravenous iron just prior to being called in for transplantation. Methods This study is a single-centre, prospective, open-label, randomised, controlled trial of oral versus intravenous iron supplements in renal transplant recipients and aims to recruit approximately 100 patients over a 12-month period. Patients will be randomised to receive a single dose of 500 mg iron polymaltose (intravenous iron group) or 2 ferrous sulphate slow-release tablets daily (oral iron group). The primary outcome is time to normalisation of haemoglobin post-transplant. Prospective power calculations have indicated that a minimum of 48 patients in each group would have to be followed up for 3 months in order to have a 90% probability of detecting a halving of the time to correction of haemoglobin levels to ≄110 g/l in iron-treated patients, assuming an α of 0.05. All eligible adult patients undergoing renal transplantation at the Princess Alexandra Hospital will be offered participation in the trial. Exclusion criteria will include iron overload (transferrin saturation >50% or ferritin >800 ÎŒg/l), or previous intolerance of either oral or intravenous iron supplements. Discussion If the trial shows a reduction in the time to correction of anaemia with intravenous iron or less side effects than oral iron, then intravenous iron may become the standard of treatment in this patient group

    Utilizing Technology for Diet and Exercise Change in Complex Chronic Conditions Across Diverse Environments (U-DECIDE): Protocol for a Randomized Controlled Trial

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    BACKGROUND: The metabolic syndrome is common across many complex chronic disease groups. Advances in health technology have provided opportunities to support lifestyle interventions. OBJECTIVE: The purpose of this study is to test the feasibility of a health technology-assisted lifestyle intervention in a patient-led model of care. METHODS: The study is a single-center, 26-week, randomized controlled trial. The setting is specialist kidney and liver disease clinics at a large Australian tertiary hospital. The participants will be adults with a complex chronic condition who are referred for dietetic assessment and display at least one feature of the metabolic syndrome. All participants will receive an individualized assessment and advice on diet quality from a dietitian, a wearable activity monitor, and standard care. Participants randomized to the intervention group will receive access to a suite of health technologies from which to choose, including common base components (text messages) and optional components (online and mobile app–based nutrition information, an online home exercise program, and group-based videoconferencing). Exposure to the optional aspects of the intervention will be patient-led, with participants choosing their preferred level of engagement. The primary outcome will be the feasibility of delivering the program, determined by safety, recruitment rate, retention, exposure uptake, and telehealth adherence. Secondary outcomes will be clinical effectiveness, patient-led goal attainment, treatment fidelity, exposure demand, and participant perceptions. Primary outcome data will be assessed descriptively and secondary outcomes will be assessed using an analysis of covariance. This study will provide evidence on the feasibility of the intervention in a tertiary setting for patients with complex chronic disease exhibiting features of the metabolic syndrome. RESULTS: The study was funded in 2019. Enrollment has commenced and is expected to be completed by June 2022. Data collection and follow up are expected to be completed by December 2022. Results from the analyses based on primary outcomes are expected to be submitted for publication by June 2023. CONCLUSIONS: The study will test the implementation of a health technology–assisted lifestyle intervention in a tertiary outpatient setting for a diverse group of patients with complex chronic conditions. It is novel in that it embeds patient choice into intervention exposure and will inform health service decision-makers in regards to the feasibility of scale and spread of technology-assisted access to care for a broader reach of specialist services. TRIAL REGISTRATION: Australian New Zealand Clinical Trial Registry ACTRN12620001282976; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=378337 INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/3755

    Comparison of the influence of cyclosporine and tacrolimus on the pharmacokinetics of prednisolone in adult male kidney transplant recipients

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    Cyclosporine has been observed to precipitate cushingoid features in kidney transplant recipients already on prednisolone. Some pharmacokinetic studies have demonstrated increased prednisolone exposure in patients on cyclosporine therapy compared with azathioprine, whereas other studies have found no difference. The objective of this study was to determine whether cyclosporine impacts on prednisolone exposure as compared with tacrolimus

    Do aluminium-based phosphate binders continue to have a role in contemporary nephrology practice?

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    Background: Aluminium-containing phosphate binders have long been used for treatment of hyperphosphatemia in dialysis patients. Their safety became controversial in the early 1980's after reports of aluminium related neurological and bone disease began to appear. Available historical evidence however, suggests that neurological toxicity may have primarily been caused by excessive exposure to aluminium in dialysis fluid, rather than aluminium-containing oral phosphate binders. Limited evidence suggests that aluminium bone disease may also be on the decline in the era of aluminium removal from dialysis fluid, even with continued use of aluminium binders

    Carvedilol and cardiac biomarkers in dialysis patients: Secondary analysis of a randomized controlled trial

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    Published online: December 04, 2017Background/Aims: Cardiac biomarkers are associated with cardiac abnormalities and adverse outcomes in dialysis patients. Our aim was to report the effect of the beta-blocker carvedilol on cardiac biomarkers in adult dialysis patients. Methods: The Beta-Blocker to Lower Cardiovascular Dialysis Events Feasibility Study was a randomized controlled trial comparing carvedilol to placebo. Serum and plasma were collected before the run-in, then 6 and 12 months post-randomization to measure B-type Natriuretic Peptide (BNP), N-terminal BNP (NT-ProBNP), high-sensitivity cardiac troponins I (hs-TnI) and T (hs-TnT), and galectin-3. Left ventricular global longitudinal strain (GLS) was measured by echocardiography at baseline. Results: Seventy-two participants were recruited of whom 49 completed the run-in and were randomized to carvedilol (n=26) or placebo (n=23). Baseline echocardiography demonstrated median (inter-quartile range) GLS of -14.27% (-16.63 to -11.93). NTproBNP and hs-TnT correlated with GLS (Spearman’s rho=0.34 [p=0.018] and rho=0.28 [p=0.049], respectively). Median change scores from baseline to 12 months did not differ significantly between participants with complete biomarker data randomized to carvedilol (n=15) or placebo (n=16) for any biomarkers. Conclusions: NT-proBNP and hs-TnT were associated with GLS. However, changes in levels of the biomarkers from baseline to 12 months were not different between groups randomized to carvedilol and placebo.Matthew A. Roberts, Darsy Darssan, Sunil V. Badve, Robert P. Carroll, Magid A. Fahim, Brian A. Haluska, Carmel M. Hawley, Nicole M. Isbel, Mark R. Marshall, Elaine M. Pascoe, Eugenie Pedagogos, Helen L. Pilmore, Paul Snelling, Tony Stanton, Ken-Soon Tan, Andrew M. Tonkin, Liza A. Vergara, Francesco L. Ierin

    Cardiac and vascular structure and function parameters do not improve with alternate nightly home hemodialysis: An interventional cohort study

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    Background: Nightly extended hours hemodialysis may improve left ventricular hypertrophy and function and endothelial function but presents problems of sustainability and increased cost. The effect of alternate nightly home hemodialysis (NHD) on cardiovascular structure and function is not known

    Chronic Kidney Disease and Coronary Artery Disease: JACC State-of-the-Art Review

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    Chronic kidney disease (CKD) is a major risk factor for coronary artery disease (CAD). As well as their high prevalence of traditional CAD risk factors, such as diabetes and hypertension, persons with CKD are also exposed to other nontraditional, uremia-related cardiovascular disease risk factors, including inflammation, oxidative stress, and abnormal calcium-phosphorus metabolism. CKD and end-stage kidney disease not only increase the risk of CAD, but they also modify its clinical presentation and cardinal symptoms. Management of CAD is complicated in CKD patients, due to their\ua0likelihood of comorbid conditions and potential for side effects during interventions. This summary of the Kidney\ua0Disease: Improving Global Outcomes (KDIGO) Controversies Conference on CAD and CKD (including end-stage\ua0kidney disease and\ua0transplant recipients) seeks to improve understanding of the epidemiology, pathophysiology, diagnosis, and\ua0treatment of CAD in CKD and to identify knowledge gaps, areas of controversy, and\ua0priorities for research

    A new look at the LTR retrotransposon content of the chicken genome

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    BACKGROUND: LTR retrotransposons contribute approximately 10 % of the mammalian genome, but it has been previously reported that there is a deficit of these elements in the chicken relative to both mammals and other birds. A novel LTR retrotransposon classification pipeline, LocaTR, was developed and subsequently utilised to re-examine the chicken LTR retrotransposon annotation, and determine if the proposed chicken deficit is biologically accurate or simply a technical artefact. RESULTS: Using LocaTR 3.01 % of the chicken galGal4 genome assembly was annotated as LTR retrotransposon-derived elements (nearly double the previous annotation), including 1,073 that were structurally intact. Element distribution is significantly correlated with chromosome size and is non-random within each chromosome. Elements are significantly depleted within coding regions and enriched in gene sparse areas of the genome. Over 40 % of intact elements are found in clusters, unrelated by age or genera, generally in poorly recombining regions. The transcription of most LTR retrotransposons were suppressed or incomplete, but individual domain and full length retroviral transcripts were produced in some cases, although mostly with regularly interspersed stop codons in all reading frames. Furthermore, RNAseq data from 23 diverse tissues enabled greater characterisation of the co-opted endogenous retrovirus Ovex1. This gene was shown to be expressed ubiquitously but at variable levels across different tissues. LTR retrotransposon content was found to be very variable across the avian lineage and did not correlate with either genome size or phylogenetic position. However, the extent of previous, species-specific LTR retrotransposon annotation appears to be a confounding factor. CONCLUSIONS: Use of the novel LocaTR pipeline has nearly doubled the annotated LTR retrotransposon content of the chicken genome compared to previous estimates. Further analysis has described element distribution, clustering patterns and degree of expression in a variety of adult tissues, as well as in three embryonic stages. This study also enabled better characterisation of the co-opted gamma retroviral envelope gene Ovex1. Additionally, this work suggests that there is no deficit of LTR retrotransposons within the Galliformes relative to other birds, or to mammalian genomes when scaled for the three-fold difference in genome size
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