1,299 research outputs found

    Adipocyte Liver Kinase b1 Suppresses Beige Adipocyte Renaissance Through Class IIa Histone Deacetylase 4.

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    Uncoupling protein 1+ beige adipocytes are dynamically regulated by environment in rodents and humans; cold induces formation of beige adipocytes, whereas warm temperature and nutrient excess lead to their disappearance. Beige adipocytes can form through de novo adipogenesis; however, how "beiging" characteristics are maintained afterward is largely unknown. In this study, we show that beige adipocytes formed postnatally in subcutaneous inguinal white adipose tissue lost thermogenic gene expression and multilocular morphology at the adult stage, but cold restored their beiging characteristics, a phenomenon termed beige adipocyte renaissance. Ablation of these postnatal beige adipocytes inhibited cold-induced beige adipocyte formation in adult mice. Furthermore, we demonstrated that beige adipocyte renaissance was governed by liver kinase b1 and histone deacetylase 4 in white adipocytes. Although neither presence nor thermogenic function of uncoupling protein 1+ beige adipocytes contributed to metabolic fitness in adipocyte liver kinase b1-deficient mice, our results reveal an unexpected role of white adipocytes in maintaining properties of preexisting beige adipocytes

    The Stellar Population of Lyman-alpha Emitting Galaxies at z ~ 5.7

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    We present a study of three Lyman-alpha emitting galaxies (LAEs), selected via a narrow-band survey in the GOODS northern field, and spectroscopically confirmed to have redshifts of z ~ 5.65. Using HST ACS and Spitzer IRAC data, we constrain the rest-frame UV-to-optical spectral energy distributions (SEDs) of the galaxies. Fitting stellar population synthesis models to the observed SEDs, we find best-fit stellar populations with masses between ~ 10^9 - 10^10 M_sun and ages between ~ 5 - 100 Myr, assuming a simple starburst star formation history. However, stellar populations as old as 700 Myr are admissible if a constant star formation rate model is considered. Very deep near-IR observations may help to narrow the range of allowed models by providing extra constraints on the rest-frame UV spectral slope. Our narrow-band selected objects and other IRAC-detected z ~ 6 i'-dropout galaxies have similar 3.6 um magnitudes and z' - [3.6] colors, suggesting that they posses stellar populations of similar masses and ages. This similarity may be the result of a selection bias, since the IRAC-detected LAEs and i'-dropouts probably only sample the bright end of the luminosity function. On the other hand, our LAEs have blue i' - z' colors compared to the i'-dropouts, and would have been missed by the i'-dropout selection criterion. A better understanding of the overlap between the LAE and the i'-dropout populations is necessary in order to constrain the properties of the overall high-redshift galaxy population, such as the total stellar mass density at z ~ 6.Comment: 10 pages, 8 figures. Accepted for publication in Ap

    Visualization of lithium-ion transport and phase evolution within and between manganese oxide nanorods.

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    Multiple lithium-ion transport pathways and local phase changes upon lithiation in silver hollandite are revealed via in situ microscopy including electron diffraction, imaging and spectroscopy, coupled with density functional theory and phase field calculations. We report unexpected inter-nanorod lithium-ion transport, where the reaction fronts and kinetics are maintained within the neighbouring nanorod. Notably, this is the first time-resolved visualization of lithium-ion transport within and between individual nanorods, where the impact of oxygen deficiencies is delineated. Initially, fast lithium-ion transport is observed along the long axis with small net volume change, resulting in two lithiated silver hollandite phases distinguishable by orthorhombic distortion. Subsequently, a slower reaction front is observed, with formation of polyphase lithiated silver hollandite and face-centred-cubic silver metal with substantial volume expansion. These results indicate lithium-ion transport is not confined within a single nanorod and may provide a paradigm shift for one-dimensional tunnelled materials, particularly towards achieving high-rate capability

    Epidemiologic observations guiding clinical application of a urinary peptidomic marker of diastolic left ventricular dysfunction

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    Hypertension, obesity, and old age are major risk factors for left ventricular (LV) diastolic dysfunction (LVDD), but easily applicable screening tools for people at risk are lacking. We investigated whether HF1, a urinary biomarker consisting of 85 peptides, can predict over a 5-year time span mildly impaired diastolic LV function as assessed by echocardiography. In 645 white Flemish (50.5% women; 50.9 years [mean]), we measured HF1 by capillary electrophoresis coupled with mass spectrometry in 2005-2010. We measured early (E) and late (A) peak velocities of the transmitral blood flow and early (e') and late (a') mitral annular peak velocities and their ratios in 2009-2013. In multivariable-adjusted analyses, per 1-standard deviation increment in HF1, e' was -0.193 cm/s lower (95% confidence interval: -0.352 to -0.033; P = .018) and E/e' 0.174 units higher (0.005-0.342; P = .043). Of 645 participants, 179 (27.8%) had LVDD at follow-up, based on impaired relaxation in 69 patients (38.5%) or an elevated filling pressure in the presence of a normal (74 [43.8%]) or low (36 [20.1%]) age-specific E/A ratio. For a 1-standard deviation increment in HF1, the adjusted odds ratio was 1.37 (confidence interval, 1.07-1.76; P = .013). The integrated discrimination (+1.14%) and net reclassification (+31.7%) improvement of the optimized HF1 threshold (-0.350) in discriminating normal from abnormal diastolic LV function at follow-up over and beyond other risk factors was significant (P ≤ .024). In conclusion, HF1 may allow screening for LVDD over a 5-year horizon in asymptomatic people

    Flecainide Paradoxically Activates Cardiac Ryanodine Receptor Channels under Low Activity Conditions: A Potential Pro-Arrhythmic Action.

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    Cardiac ryanodine receptor (RyR2) mutations are implicated in the potentially fatal catecholaminergic polymorphic ventricular tachycardia (CPVT) and in atrial fibrillation. CPVT has been successfully treated with flecainide monotherapy, with occasional notable exceptions. Reported actions of flecainide on cardiac sodium currents from mice carrying the pro-arrhythmic homozygotic RyR2-P2328S mutation prompted our explorations of the effects of flecainide on their RyR2 channels. Lipid bilayer electrophysiology techniques demonstrated a novel, paradoxical increase in RyR2 activity. Preceding flecainide exposure, channels were mildly activated by 1 mM luminal Ca2+ and 1 µM cytoplasmic Ca2+, with open probabilities (Po) of 0.03 ± 0.01 (wild type, WT) or 0.096 ± 0.024 (P2328S). Open probability (Po) increased within 0.5 to 3 min of exposure to 0.5 to 5.0 µM cytoplasmic flecainide, then declined with higher concentrations of flecainide. There were no such increases in a subset of high Po channels with Po ≥ 0.08, although Po then declined with ≥5 µM (WT) or ≥50 µM flecainide (P2328S). On average, channels with Po < 0.08 were significantly activated by 0.5 to 10 µM of flecainide (WT) or 0.5 to 50 µM of flecainide (P2328S). These results suggest that flecainide can bind to separate activation and inhibition sites on RyR2, with activation dominating in lower activity channels and inhibition dominating in more active channels

    Utilizing recycled ceramic aggregates obtained from tile industry in the design of open graded wearing course on both laboratory and in situ basis

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    The purpose of the research was to evaluate the technical feasibility of using porcelain and ceramic stoneware tile wastes as aggregate replacement in hot bituminous open graded wearing courses. It is believed that it would reduce the environmental effects of wastes disposal and the natural aggregate demand. The investigated bituminous mix course was an open graded wearing course. Ceramic tile industry wastes were treated to obtain recycled aggregates. These aggregates were characterized and tested to see their suitability to be utilized in bituminous mixtures. The design process of mixture consisted on the study of mixtures prepared with natural and recycled aggregates. The mixtures were produced in both the laboratory and an asphalt plant basis, evaluating the influence of in situ production and scale factors. Recycled ceramic aggregates content was established to obtain appropriate mechanical and superficial characteristics, besides maximizing re-utilization of recycled materials. Up to 30% of recycled ceramic aggregates content by aggregates weight was found to be adequate. However, the partial substitution of natural aggregate by recycled ceramic aggregates involved higher water sensitivity in the mixture. The open graded wearing course with recycled ceramic aggregates was considered to be suitable for medium to low traffic volume roads, though further research is deemed to be necessary for technical and economical viability. (C) 2013 Elsevier Ltd. All rights reserved.This research would not have been possible without the support of the Research and Development Program of the Institute for Small and Medium Industry from Valencia (IMPIVA, No Exp. IMI-DTF/2011/56), financed by the European Union under the Operational Program of the European Regional Development Fund (ERDF).Silvestre Martínez, R.; Medel Colmenar, E.; García García, A.; Navas, J. (2013). Utilizing recycled ceramic aggregates obtained from tile industry in the design of open graded wearing course on both laboratory and in situ basis. Materials and Design. 50:471-478. https://doi.org/10.1016/j.matdes.2013.03.041S4714785

    Biomarkers to assess right heart pressures in recipients of a heart transplant: a proof-of-concept study

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    Background: This proof-of-concept study investigated the feasibility of using biomarkers to monitor right heart pressures (RHP) in heart transplanted (HTx) patients. Methods: In 298 patients, we measured 7.6 years post-HTx mean pressures in the right atrium (mRAP) and pulmonary artery (mPAP) and capillaries (mPCWP) along with plasma high-sensitivity troponin T (hsTnT), a marker of cardiomyocyte injury, and the multidimensional urinary classifiers HF1 and HF2, mainly consisting of dysregulated collagen fragments. Results: In multivariable models, mRAP and mPAP increased with hsTnT (per 1-SD, +0.91 and +1.26 mm Hg; P &lt; 0.0001) and with HF2 (+0.42 and +0.62 mm Hg; P ≤ 0.035), but not with HF1. mPCWP increased with hsTnT (+1.16 mm Hg; P &lt; 0.0001), but not with HF1 or HF2. The adjusted odds ratios for having elevated RHP (mRAP, mPAP or mPCWP ≥10, ≥24, ≥17 mm Hg, respectively) were 1.99 for hsTnT and 1.56 for HF2 (P ≤ 0.005). In detecting elevated RHPs, areas under the curve were similar for hsTnT and HF2 (0.63 vs 0.65; P = 0.66). Adding hsTnT continuous or per threshold or HF2 continuous to a basic model including all covariables did not increase diagnostic accuracy (P ≥ 0.11), whereas adding HF2 per optimized threshold increased both the integrated discrimination (+1.92%; P = 0.023) and net reclassification (+30.3%; P = 0.010) improvement. Conclusions: Correlating RHPs with noninvasive biomarkers in HTx patients is feasible. However, further refinement and validation of such biomarkers is required before their clinical application can be considered

    Using ceramic wastes from tile industry as a partial substitute of natural aggregates in hot mix asphalt binder courses

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    The technical feasibility of using recycled ceramic aggregates as a partial replacement of natural aggregates in hot mix asphalt was investigated. Recycled ceramic aggregates were obtained crushing stoneware and porcelain tile wastes from the ceramic industry. Both natural and recycled aggregates were characterized by suitability tests to be utilized in bituminous mixtures. Asphalt concrete binder course mixtures were designed through the Marshall method and the European CE marking standards. The mixtures were produced in both laboratory and asphalt plant, evaluating the influence of real production and scale factors. The addition of recycled ceramic aggregates increased binder, filler and air void contents, as well as the resistance to plastic deformation and the retained indirect tensile resistance after immersion. Nonetheless, worse moisture susceptibility with compressive strength and worse values of Marshall stability and deformation were observed. Up to 30% of natural aggregates were replaced by recycled ceramic aggregates with good mechanical conditions according to Spanish specifications. The main conclusion was that hot bituminous mixtures with a reasonable addition of recycled ceramic aggregates can satisfy binder course performance requirements for medium-low volume roads.This research would not have been possible without the support of the Research and Development Program of the Institute for Small and Medium Industry from Valencia (IMPIVA, No. Exp. IMIDTF/2011/56), financed by the European Union under the Operational Program of the European Regional Development Fund (ERDF).Martínez, RS.; Medel Colmenar, E.; García García, A.; Navas Gomez, J. (2013). Using ceramic wastes from tile industry as a partial substitute of natural aggregates in hot mix asphalt binder courses. Construction and Building Materials. 45:115-122. doi:10.1016/j.conbuildmat.2013.03.058S1151224
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