3,193 research outputs found

    The radio jets of SS 433 at millimetre wavelengths

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    Context. SS 433 is historically a well-known microquasar in the Galaxy that has been deeply studied during the four decades elapsed since its discovery. However, observations at very high radio frequencies with good angular resolution are still very scarce in the literature. The present paper tries to partially fill this gap using archival data of the source obtained with the Atacama Large Millimeter Array (ALMA). Aims. We aim to study the SS 433 jet properties at radio frequencies corresponding to millimetre wavelengths where the synchrotron emitting particles are expected to lose their energy much faster than at lower frequencies of centimetre wavelengths. Results. A resolved view of the SS 433 radio core and jets is presented. In addition to spectral index and magnetic field measurements, we are able to estimate the age of the oldest visible ejecta still radiating significantly at millimetre wavelengths. By combining our findings with those of previous authors at lower frequencies, we confirm that the energy loss of the radiating electrons is dominated by adiabatic expansion instead of synchrotron radiative losses. In addition, we find suggestive evidence for the previously proposed period of slowed expansion within the first months of the ejecta flow, needed to simultaneously match the radiative lifetime observed in the centimetre domain. Our results argue for the need for future coordinated millimetre and centimetre interferometric observations with good time sampling throughout the SS 433 precessional cycle to better understand energetic processes in stellar relativistic jets.Comment: 14 pages, 7 figures, Accepted for publication in Astronomy & Astrophysic

    Phases I–III Clinical Trials Using Adult Stem Cells

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    First randomized clinical trials have demonstrated that stem cell therapy can improve cardiac recovery after the acute phase of myocardial ischemia and in patients with chronic ischemic heart disease. Nevertheless, some trials have shown that conflicting results and uncertainties remain in the case of mechanisms of action and possible ways to improve clinical impact of stem cells in cardiac repair. In this paper we will examine the evidence available, analyze the main phase I and II randomized clinical trials and their limitations, discuss the key points in the design of future trials, and depict new directions of research in this fascinating field

    Functional Multipotency of Stem Cells: What Do We Need from Them in the Heart?

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    After more than ten years of human research in the field of cardiac regenerative medicine, application of stem cells in different phases of ischemic heart disease has come to age. Randomized clinical trials have demonstrated that stem cell therapy can improve cardiac recovery after the acute phase of myocardial ischemia and in patients with chronic ischemic heart disease, and several efficacy phase III trials with clinical endpoints are on their way. Nevertheless, a complete knowledge on the mechanisms of action of stem cells still remains elusive. Of the three main mechanisms by which stem cells could exert their benefit, paracrine signaling from the administered cells and stimulation of endogenous repair are nowadays the most plausible ones. However, in this review we will define and discuss the concept of stem cell potency and differentiation, will examine the evidence available, and will depict future directions of research

    Cell Expansion-Dependent Inflammatory and Metabolic Profile of Human Bone Marrow Mesenchymal Stem Cells

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    Stem cell therapy has emerged as a promising new area in regenerative medicine allowing the recovery of viable tissues. Among the many sources of adult stem cells, bone marrow-derived are easy to expand in culture via plastic adherence and their multipotentiality for differentiation make them ideal for clinical applications. Interestingly, several studies have indicated that MSCs expansion in vitro may be limited mainly due to cell aging related to the number of cell divisions in culture. We have determined that MSCs exhibit a progressive decline across successive passages in the expression of stem cell markers, in plasticity and in the inflammatory response, presenting low immunogenicity. We have exposed human MSCs after several passages to TLRs ligands and analyzed their inflammatory response. These cells responded to pro-inflammatory stimuli (i.e., NOS-2 expression) and to anti-inflammatory cytokines (i.e., HO1 and Arg1) until two expansions, rapidly declining upon subculture. Moreover, in the first passages, MSCs were capable to release IL1β, IL6 and IL8, as well as to produce active MMPs allowing them to migrate. Interestingly enough, after two passages, anaerobic glycolysis was enhanced releasing high levels of lactate to the extracellular medium. All these results may have important implications for the safety and efficacy of MSCs-based cell therapies

    Effectiveness of sacubitril–valsartan in cancer patients with heart failure

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    Aims Current guidelines recommend sacubitril/valsartan for patients with heart failure and reduced left ventricular ejection fraction (LVEF), but there is lack of evidence of its efficacy and safety in cancer therapy-related cardiac dysfunction (CTRCD). Our aim was to analyse the potential benefit of sacubitril/valsartan in patients with CTRCD. Methods and results We performed a retrospective multicentre registry (HF-COH) in six Spanish hospitals with cardiooncology clinics including all patients treated with sacubitril/valsartan. Demographic and clinical characteristics and laboratory and echocardiographic data were collected. Median follow-up was 4.6 [1; 11] months. Sixty-seven patients were included (median age was 63 ± 14 years; 64% were female, 87% had at least one cardiovascular risk factor). Median time from anti-cancer therapy to CTRD was 41 [10; 141] months. Breast cancer (45%) and lymphoma (39%) were the most frequent neoplasm, 31% had metastatic disease, and all patients were treated with combination antitumor therapy (70% with anthracyclines). Thirtynine per cent of patients had received thoracic radiotherapy. Baseline median LVEF was 33 [27; 37], and 21% had atrial fibrillation. Eighty-five per cent were on beta-blocker therapy and 76% on mineralocorticoid receptor antagonists; 90% of the patients were symptomatic NYHA functional class ≥II. Maximal sacubitril/valsartan titration dose was achieved in 8% of patients (50 mg b.i.d.: 60%; 100 mg b.i.d.: 32%). Sacubitril/valsartan was discontinued in four patients (6%). Baseline Nterminal pro-B-type natriuretic peptide levels (1552 pg/mL [692; 3624] vs. 776 [339; 1458]), functional class (2.2 ± 0.6 vs. 1.6 ± 0.6), and LVEF (33% [27; 37] vs. 42 [35; 50]) improved at the end of follow-up (all P values ≤0.01). No significant statistical differences were found in creatinine (0.9 mg/dL [0.7; 1.1] vs. 0.9 [0.7; 1.1]; P = 0.055) or potassium serum levels (4.5 mg/dL [4.1; 4.8] vs. 4.5 [4.2; 4.8]; P = 0.5). Clinical, echocardiographic, and biochemical improvements were found regardless of the achieved sacubitril–valsartan dose (low or medium/high doses). Conclusions Our experience suggests that sacubitril/valsartan is well tolerated and improves echocardiographic functional and structural parameters, N-terminal pro-B-type natriuretic peptide levels, and symptomatic status in patients with CTRCD.This study was funded by the Instituto de Salud Carlos III, Ministerio de Ciencia, Innovación y Universidades, Spain, and the EU—European Regional Development Fund, by means of a competitive call for excellence in research projects (PIE14/00066) as well as by the Spanish Cardiovascular Network (CIBERCV)

    Spheroidal halloysites from Patagonia, Argentina: Some aspects of their formation and applications

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    Halloysite deposits in Argentina have been identified in the province of Río Negro (Patagonia). The mineralized area occurs as altered zones in Eocene volcanic–pyroclastic rocks, dacitic to rhyolitic in composition. A comprehensive study of these deposits was carried out by means of mineralogical, geochemical and isotopic analyses. Intenseweathering has transformed the whole rock to a whitemass composed of 75% –90% halloysite+kaolinite, with cristobalite, tridymite, and quartz, as the main non-clay minerals. Ferruginous beidellite and titanium minerals are also present in minor amounts. The halloysite–kaolinite ratio ranges from 75 to 25 to 100–0. Due to the alteration of very dense rocks, halloysite morphology is predominantly spheroidal. Tubular halloysite is the main constituent in more porous rocks, but the latter are scarce in the area. Because of the predominance of the spheroidal type, the use of halloysite asHNT (halloysite nanotube) is not feasible. Nonetheless, this mineral can be modified by different organic molecules, and used to remove pollutants such as emulsified hydrocarbons and heavy metals. A special product made with this halloysite is used as sunscreen when sprayed on fruits in areas of intense solar radiation. The whiteness of this mineral is not very high due to the amount of titanium oxide present in its composition (about 1%). Nevertheless, titanium oxide is present as individual particles, so it could be removed by a mechanical process. New applications for spheroidal halloysite are currently being investigated. Moreover, depending on the price and demand, the tubular halloysite of low grade deposits could be exploited

    Magnetovolume and magnetocaloric effects in Er2Fe17

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    Combining different experimental techniques, investigations in hexagonal P63/mmc Er2Fe17 show remarkable magnetovolume anomalies below the Curie temperature, TC. The spontaneous magnetostriction reaches 1.6×10−2 at 5 K and falls to zero well above TC, owing to short-range magnetic correlations. Moreover, Er2Fe17 exhibits direct and inverse magnetocaloric effects (MCE) with moderate isothermal magnetic entropy ΔSM, and diabatic temperature ΔTad changes [ΔSM∼−4.7 J(kgK)−1 and ΔTad∼2.5 K near the TC, and ΔSM∼1.3 J(kgK)−1 and ΔTad∼−0.6 K at 40 K for ΔH=80 kOe, respectively, determined from magnetization measurements]. The existence of an inverse MCE seems to be related to a crystalline electric field-level crossover in the Er sublattice and the ferrimagnetic arrangement between the magnetic moments of the Er and Fe sublattice. The main trends found experimentally for the temperature dependence of ΔSM and ΔTad as well as for the atomic magnetic moments are qualitatively well described considering a mean-field Hamiltonian that incorporates both crystalline electric field and exchange interactions. ΔSM(T) and ΔTad(T) curves are essentially zero at ∼150 K, the temperature where the transition from direct to inverse MCE occurs. A possible interplay between the MCE and the magnetovolume anomalies is also discussed.Financial support from Spanish MICINN (MAT2011-27573-C04-02) and from the Basque Government (IT-347- 07) is acknowledged. J.L.S.Ll. acknowledges the support received from CONACYT, Mexico, under the project CB2010-01-156932, and Laboratorio Nacional de Investigaciones en Nanociencias y Nanotecnología (LINAN, IPICyT). J.A.R.V. acknowledges the support from the research project MAT2007-61621. We thank ILL and CRG-D1B for allocating neutron beamtime, and ESRF for synchrotron beamtime. The SCTs at the University of Oviedo and the technical support received from M.Sc. G. J. Labrada-Delgado and B. A. Rivera-Escoto (DMA, IPICyT) are also acknowledged

    Expression of epicardial adipose tissue thermogenic genes in patients with reduced and preserved ejection fraction heart failure

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    [Abstract] Epicardial adipose tissue has been proposed to participate in the pathogenesis of heart failure. The aim of our study was to assess the expression of thermogenic genes (Uncoupling protein 1 (UCP1), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α), and PR-domain-missing 16 (PRDM16) in epicardial adipose tissue in patients with heart failure, stablishing the difference according to left ventricular ejection fraction (reduced or preserved). Among the 75 patients in our study, 42.7% (n=32) had reduced left ventricular ejection fraction. UCP1, PGC1α and PRDM16 mRNA in EAT were significantly lower in patients with reduced left ventricular ejection fraction. Multiple regression analysis showed that age, male gender, body max index, presence of obesity, type-2-diabetes mellitus, hypertension and coronary artery disease and left ventricular ejection fraction were associated with the expression levels of UCP1, PGC1α and PRDM16 mRNA. Thermogenic genes expressions in epicardial adipose tissue (UCP1: OR 0.617, 95%CI 0.103-0.989, p=0.042; PGC1α: OR 0.416, 95%CI 0.171-0.912, p=0.031; PRDM16: OR 0.643, 95%CI 0.116-0.997, p=0.044) were showed as protective factors against the presence of heart failure with reduced left ventricular ejection fraction, and age (OR 1.643, 95%CI 1.001-3.143, p=0.026), presence of coronary artery disease (OR 6.743, 95%CI 1.932-15.301, p<0.001) and type-2-diabetes mellitus (OR 4.031, 95%CI 1.099-7.231, p<0.001) were associated as risk factors. The adequate expression of thermogenic genes has been shown as possible protective factors against heart failure with reduced ejection fraction, suggesting that a loss of functional epicardial adipose tissue brown-like features would participate in a deleterious manner on heart metabolism. Thermogenic genes could represent a future novel therapeutic target in heart failure.Ministerio de Salud, Servicios Sociales e Igualdad; PI13/02542Ministerio de Salud, Servicios Sociales e Igualdad; PI11/01661Red de Investigación Cardiovascular (España), RD12/0042/003

    Femtosecond XUV–IR induced photodynamics in the methyl iodide cation

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    The time-resolved photodynamics of the methyl iodide cation (CH3I+) are investigated by means of femtosecond XUV–IR pump–probe spectroscopy. A time-delay-compensated XUV monochromator is employed to isolate a specific harmonic, the 9th harmonic of the fundamental 800 nm (13.95 eV, 88.89 nm), which is used as a pump pulse to prepare the cation in several electronic states. A time-delayed IR probe pulse is used to probe the dissociative dynamics on the first excited A~2A1\tilde {A}\enspace {}^{2}\mathrm{A}_{1} state potential energy surface. Photoelectrons and photofragment ions—CH3+{\mathrm{C}\mathrm{H}}_{3}^{+} and I+—are detected by velocity map imaging. The experimental results are complemented with high level ab initio calculations for the potential energy curves of the electronic states of CH3I+ as well as with full dimension on-the-fly trajectory calculations on the first electronically excited state A~2A1\tilde {A}\enspace {}^{2}\mathrm{A}_{1}, considering the presence of the IR pulse. The CH3+{\mathrm{C}\mathrm{H}}_{3}^{+} and I+ pump–probe transients reflect the role of the IR pulse in controlling the photodynamics of CH3I+ in the A~2A1\tilde {A}\enspace {}^{2}\mathrm{A}_{1} state, mainly through the coupling to the ground state X~2E3/2,1/2\tilde {X}\enspace {}^{2}\mathrm{E}_{3/2,1/2} and to the excited B~2E\tilde {B}\enspace {}^{2}\mathrm{E} state manifold. Oscillatory features are observed and attributed to a vibrational wave packet prepared in the A~2A1\tilde {A}\enspace {}^{2}\mathrm{A}_{1} state. The IR probe pulse induces a coupling between electronic states leading to a slow depletion of CH3+{\mathrm{C}\mathrm{H}}_{3}^{+} fragments after the cation is transferred to the ground X~2E3/2,1/2\tilde {X}\enspace {}^{2}\mathrm{E}_{3/2,1/2} states and an enhancement of I+ fragments by absorption of IR photons yielding dissociative photoionization
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