348 research outputs found

    The amount and utilization of organic phosphorus in soils

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    Call number: LD2668 .T4 1950 G4Master of Scienc

    Consumption of Atmospheric Isoprene in Soil

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    Natural vegetation annually emits 503 Tg yr−1 of isoprene (2-methyl-1,3 butadiene) to the global atmosphere where it reacts very rapidly with hydroxyl radicals and strongly regulates atmospheric chemistry. Current models of the compound\u27s chemical behavior assume the atmosphere is the only significant sink; however, there is evidence that soil may consume isoprene. Here we show through field and laboratory studies that soil exposed to isoprene at low mixing ratios removed isoprene to concentrations below those commonly observed in forest canopies, and that the removal of isoprene was biologically mediated. On the basis of laboratory studies with soil from several different ecosystems worldwide, we provide a first approximation of a global annual soil sink for isoprene of 20.4 Tg yr−1, suggesting a soil sink should be included in models that attempt to describe the effect of isoprene emission on atmospheric chemical processes

    Enhanced inflammatory responses to toll-like receptor 2/4 stimulation in type 1 diabetic coronary artery endothelial cells: the effect of insulin

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    <p>Abstract</p> <p>Background</p> <p>Endothelial inflammatory responses mediated by Toll-like receptors (TLRs), particularly TLR2 and TLR4, play an important role in atherogenesis. While Type 1 diabetes (T1D) promotes the development and progression of atherosclerosis, the effect of T1D on TLR2/4-mediated inflammatory responses in coronary artery endothelial cells (CAECs) remains unclear.</p> <p>Methods</p> <p>We tested the hypothesis that diabetic CAECs have enhanced inflammatory responses to TLR2/4 stimulation. Non-diabetic and diabetic CAECs were treated with TLR2 agonist peptidoglycan and TLR4 agonist lipopolysaccharide. The expression of ICAM-1, IL-6 and IL-8 were analyzed by real-time PCR, immunoblotting and ELISA, and NF-κB activation by immunoblotting and immunostaining. In additional experiments, insulin was added before TLR stimulation to determine whether insulin deficiency alone is responsible for the alteration of TLR2/4-mediated inflammatory responses.</p> <p>Results</p> <p>Stimulation of TLR2 or TLR4 induced NF-κB activation, and the expression of ICAM-1, IL-6 and IL-8. Interestingly, the expression of inflammatory mediators was significantly enhanced in diabetic cells. The enhanced inflammatory responses correlated with augmented NF-κB activation in the absence of a change in TLR2 or TLR4 protein levels. Further, pretreatment of diabetic cells with insulin failed to suppress the enhanced inflammatory responses.</p> <p>Conclusions</p> <p>Diabetic CAECs have enhanced inflammatory responses to stimulation of TLR2 or TLR4, and insulin alone is insufficient to correct the hyper-inflammatory responses. The mechanism underlying the enhanced inflammatory responses appears to be augmentation of pro-inflammatory signaling, rather than up-regulation of levels of TLR2 and TLR4. These findings suggest that diabetic CAECs adopt a hyper-inflammatory phenotype and that this endothelial phenotypic change may predispose coronary artery to atherogenesis.</p

    Heart Transplant and Ventricular Assist: Cardiac Surgery and Heart Failure Perspective

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    For nearly 60 years, there have been two surgical treatment options for individuals with severe advanced heart failure: heart transplantation or implantation of a left ventricular assist device. As these fields have advanced in parallel, improvements in surgical technique, device development, and patient selection have improved outcomes for both therapies. Development of a comprehensive approach to the management of the most severe forms of advanced heart failure requires a deep understanding of both heart transplantation and durable ventricular assistance, including recent advancements in both fields. This article will review the substantial progress in the fields of heart transplantation and mechanical left ventricular assistance, including recent changes to organ allocation prioritization and left ventricular assist device evaluation, both of which have dramatically influenced practice in these fields

    Clinical outcomes and healthcare expenditures in the real world with left ventricular assist devices - The CLEAR-LVAD study

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    BACKGROUND: Several distinctly engineered left ventricular assist devices (LVADs) are in clinical use. However, contemporaneous real world comparisons have not been conducted, and clinical trials were not powered to evaluate differential survival outcomes across devices. OBJECTIVES: Determine real world survival outcomes and healthcare expenditures for commercially available durable LVADs. METHODS: Using a retrospective observational cohort design, Medicare claims files were linked to manufacturer device registration data to identify de-novo, durable LVAD implants performed between January 2014 and December 2018, with follow-up through December 2019. Survival outcomes were compared using a Cox proportional hazards model stratified by LVAD type and validated using propensity score matching. Healthcare resource utilization was analyzed across device types by using nonparametric bootstrap analysis methodology. Primary outcome was survival at 1-year and total Part A Medicare payments. RESULTS: A total of 4,195 de-novo LVAD implants were identified in fee-for-service Medicare beneficiaries (821 HeartMate 3; 1,840 HeartMate II; and 1,534 Other-VADs). The adjusted hazard ratio for mortality at 1-year (confirmed in a propensity score matched analysis) for the HeartMate 3 vs HeartMate II was 0.64 (95% CI; 0.52-0.79, p\u3c 0.001) and for the HeartMate 3 vs Other-VADs was 0.51 (95% CI; 0.42-0.63, p \u3c 0.001). The HeartMate 3 cohort experienced fewer hospitalizations per patient-year vs Other-VADs (respectively, 2.8 vs 3.2 EPPY hospitalizations, p \u3c 0.01) and 6.1 fewer hospital days on average (respectively, 25.2 vs 31.3 days, p \u3c 0.01). The difference in Medicare expenditures, conditional on survival, for HeartMate 3 vs HeartMate II was -10,722,p3˘c0.001(17.410,722, p \u3c 0.001 (17.4% reduction) and for HeartMate 3 vs Other-VADs was -17,947, p \u3c 0.001 (26.1% reduction). CONCLUSIONS: In this analysis of a large, real world, United States. administrative dataset of durable LVADs, we observed that the HeartMate 3 had superior survival, reduced healthcare resource use, and lower healthcare expenditure compared to other contemporary commercially available LVADs

    New records of biting midges of the genus \u3ci\u3eCulicoides\u3c/i\u3e Latreille from the southeastern United States (Diptera: Ceratopogonidae)

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    We provide new state and county records of biting midges in the genus Culicoides Latreille (Diptera: Ceratopogonidae) from the southeastern United States collected with CDC miniature light traps during 2007–2012 in Florida, Georgia, Alabama, Mississippi, Louisiana, Arkansas, and Texas. The primary goals of the surveys were to identify the presence of exotic Culicoides, and determine the ranges of known and possible vectors of bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV). Included are the first records of: Culicoides (Amossovia) beckae Wirth and Blanton from Louisiana and Mississippi, C. (A.) oklahomensis Khalaf from Alabama and Arkansas, C. (Avaritia) alachua Jamnback and Wirth from Alabama, C. (Culicoides) neopulicaris Wirth from Alabama, C. (Drymodesmyia) butleri Wirth and Hubert from Texas, C. (Hoffmania) insignis Lutz from Mississippi, C. (Oecacta) barbosai Wirth and Blanton from Georgia, C. (Silvaticulicoides) loisae Jamnback from Alabama, and C. kirbyi Glick and Mullen from Mississippi. We also provide new Florida county records for C. alachua, C. barbosai, C. (Beltranmyia) hollensis (Melander and Brues), C. insignis, and C. (Monoculicoides) sonorensis Wirth and Jones; a new Georgia county record for C. alachua; and new Alabama county records for C. insignis, and C. sonorensis

    Cryogenics free production of hyperpolarized 129Xe and 83Kr for biomedical MRI applications

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    As an alternative to cryogenic gas handling, hyperpolarized (hp) gas mixtures were extracted directly from the spin exchange optical pumping (SEOP) process through expansion followed by compression to ambient pressure for biomedical MRI applications. The omission of cryogenic gas separation generally requires the usage of high xenon or krypton concentrations at low SEOP gas pressures to generate hp 129Xe or hp 83Kr with sufficient MR signal intensity for imaging applications. Two different extraction schemes for the hp gasses were explored with focus on the preservation of the nuclear spin polarization. It was found that an extraction scheme based on an inflatable, pressure controlled balloon is sufficient for hp 129Xe handling, while 83Kr can efficiently be extracted through a single cycle piston pump. The extraction methods were tested for ex vivo MRI applications with excised rat lungs. Precise mixing of the hp gases with oxygen, which may be of interest for potential in vivo applications, was accomplished during the extraction process using a piston pump. The 83Kr bulk gas phase T1 relaxation in the mixtures containing more than approximately 1% O2 was found to be slower than that of 129Xe in corresponding mixtures. The experimental setup also facilitated 129Xe T1 relaxation measurements as a function of O2 concentration within excised lungs

    Cotton Irrigation in the Lower Rio Grande Valley.

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    Primary results of long-term outcomes in the MOMENTUM 3 pivotal trial and continued access protocol study phase: a study of 2200 HeartMate 3 left ventricular assist device implants

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    AIM: The MOMENTUM 3 pivotal trial established superiority of the HeartMate 3 (HM3) left ventricular assist device (LVAD), a fully magnetically levitated centrifugal-flow pump, over the HeartMate II axial-flow pump. We now evaluate HM3 LVAD outcomes in a single-arm prospective continuous access protocol (CAP) post-pivotal trial study. METHODS AND RESULTS: We enrolled 2200 HM3 implanted patients (515 pivotal trial and 1685 CAP patients) and compared outcomes including survival free of disabling stroke or reoperation to replace or remove a malfunctioning device (primary composite endpoint), overall survival and major adverse events at 2 years. The 2-year primary endpoint [76.7% vs. 74.8%; adjusted hazard ratio (HR) 0.87, 95% confidence interval (CI) 0.71-1.08, P = 0.21] and overall survival (81.2% vs. 79.0%) were similar among CAP and pivotal cohorts despite sicker patients (more intra-aortic balloon pump use and INTERMACS profile 1) in CAP who were more often intended for destination therapy. Survival was similar between the CAP and pivotal trial in transplant ineligible patients (79.1% vs. 76.7%; adjusted HR 0.89, 95% CI 0.68-1.16, P = 0.38). In a pooled analysis, the 2-year primary endpoint was similar between INTERMACS profiles 1-2 (\u27unstable\u27 advanced heart failure), profile 3 (\u27stable\u27 on inotropic therapy), and profiles 4-7 (\u27stable\u27 ambulatory advanced heart failure) (75.7% vs. 77.6% vs. 72.9%, respectively). The net burden of adverse events was lower in CAP (adjusted rate ratio 0.93, 95% CI 0.88-0.98, P = 0.006), with consequent decrease in hospitalization. CONCLUSIONS: The primary results of accumulating HM3 LVAD experience suggest a lower adverse event burden and similar survival compared to the pivotal MOMENTUM 3 trial
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