253 research outputs found

    Utilización de stent autoexpandible en canino con colapso traqueal

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    Tracheal collapse occurs mainly in small breed dogs, with ages ranging 5-9 years old. Symptoms may include breathing difficulty, chronic dry cough, rales, dyspnea, cyanosis and syncope. Surgical treatment is indicated in patients that do not respond to medication and have an advanced degree of tracheal collapse (reduction of tracheal lumen of 50% or more) and when collapse occurs in the intra-thoracic portion of the organ. Less invasive surgical techniques are preferred for high-risk patients, consisting in the placement of a self-expanding stent in the tracheal lumen. In a 14-year-old Shitzu dog, weighing 9 kg, with grade 5 tracheal collapse, video-endoscopy and digitalized radiographs were performed to determine the length and diameter of the appropriate stent. A self-expanding platinol stent, 10 mm in diameter and 100 mm in length, was used. After surgery, recovery was quick, and the endotracheal tube could be removed after 5 minutes without difficulties. Respiratory improvement after surgery was immediate and without complications.El colapso traqueal canino se presenta principalmente en razas pequeñas, entre los 5 y 9 años, pudiendo manifestar dificultad respiratoria, tos seca crónica, estertores, disnea, cianosis e incluso síncope. El tratamiento quirúrgico está indicado en pacientes que no responden a la medicación y presentan un grado de colapso avanzado (disminución de la luz traqueal del 50% o más) y cuando tal disfunción ocurre en la porción intratorácica. La técnica utilizada en este caso fue la menos invasiva y de elección para pacientes de alto riesgo, consistente en la colocación de una endoprótesis autoexpandible en la luz traqueal. En el paciente Shitzu, de 14 años, 9 kg de peso, con colapso traqueal grado 5, se realizó videoendoscopía y radiografías digitalizadas para determinar la longitud y diámetro del stent apropiado. Se utilizó un stent metálico de platinol autoexpandible de 10 mm de diámetro por 100 mm de longitud. La recuperación anestésica fue rápida y tranquila, pudiendo retirarse el tubo endotraqueal al cabo de 5 minutos sin que se presentaran contratiempos. La mejoría respiratoria, luego de la finalización del procedimiento, fue inmediata y sin complicaciones

    Earthquake hazard characterization by using entropy: application to northern Chilean earthquakes

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    The mechanical description of the seismic cycle has an energetic analogy in terms of statistical physics and the second law of thermodynamics. In this context, an earthquake can be considered a phase transition, where continuous reorganization of stresses and forces reflects an evolution from equilibrium to non-equilibrium states, and we can use this analogy to characterize the earthquake hazard of a region. In this study, we used 8 years (2007–2014) of high-quality Integrated Plate Boundary Observatory Chile (IPOC) seismic data for &gt; 100 000 earthquakes in northern Chile to test the theory that Shannon entropy, H, is an indicator of the equilibrium state of a seismically active region. We confirmed increasing H reflects the irreversible transition of a system and is linked to the occurrence of large earthquakes. Using variation in H, we could detect major earthquakes and their foreshocks and aftershocks, including the 2007 Mw 7.8 Tocopilla earthquake, the 2014 Mw 8.1 Iquique earthquake, and the 2010 and 2011 Calama earthquakes (Mw 6.6 and 6.8, respectively). Moreover, we identified possible periodic seismic behaviour between 80 and 160 km depth.</p

    Leishmania isoenzyme polymorphisms in Ecuador: Relationships with geographic distribution and clinical presentation

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    Background: Determinants of the clinical presentation of the leishmaniases are poorly understood but Leishmania species and strain differences are important. To examine the relationship between clinical presentation, species and isoenzyme polymorphisms, 56 Leishmania isolates from distinct presentations of American tegumentary leishmaniasis (ATL) from Ecuador were analyzed. Methods: Isolates were characterized by multilocus enzyme electrophoresis for polymorphisms of 11 isoenzymes. Patients were infected in four different ecologic regions: highland and lowland jungle of the Pacific coast, Amazonian lowlands and Andean highlands. Results: Six Leishmania species constituting 21 zymodemes were identified: L. (Viannia) panamensis (21 isolates, 7 zymodemes), L. (V.) guyanensis (7 isolates, 4 zymodemes), L. (V.) braziliensis (5 isolates, 3 zymodemes), L. (Leishmania) mexicana (11 isolates, 4 zymodemes), L. (L.) amazonensis (10 isolates, 2 zymodemes) and L. (L.) major (2 isolates, 1 zymodeme). L. panamensis was the species most frequently identified in the Pacific region and was associated with several clinical variants of cutaneous disease (CL); eight cases of leishmaniasis recidiva cutis (LRC) found in the Pacific highlands were associated with 3 zymodemes of this species. Mucocutaneous leishmaniasis found only in the Amazonian focus was associated with 3 zymodemes of L. braziliensis. The papular variant of CL, Uta, found in the Andean highlands was related predominantly with a single zymodeme of L. mexicana. Conclusion: Our data show a high degree of phenotypic variation within species, and some evidence for associations between specific variants of ATL (i.e. Uta and LRC) and specific Leishmania zymodemes. This study further defines the geographic distribution of Leishmania species and clinical variants of ATL in Ecuador

    Radical-containing ultrafine particulate matter initiates epithelial-to-mesenchymal transitions in airway epithelial cells

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    Environmentally persistent free radicals (EPFRs) in combustion generated particulate matter (PM) are capable of inducing pulmonary pathologies and contributing to the development of environmental asthma. In vivo exposure of infant rats to EPFRs demonstrates their ability to induce airway hyperresponsiveness to methacholine, a hallmark of asthma. However, the mechanisms by which combustion-derived EPFRs elicit in vivo responses remain elusive. In this study, we used a chemically defined EPFR consisting of approximately 0.2 μm amorphrous silica containing 3% cupric oxide with the organic pollutant 1,2-dichlorobenzene (DCB-230). DCB-230 possesses similar radical content to urban-collected EPFRs but offers several advantages, including lack of contaminants and chemical uniformity. DCB-230 was readily taken up by BEAS-2B and at high doses (200 μg/cm2) caused substantial necrosis. At low doses (20 μg/cm2), DCB-230 particles caused lysosomal membrane permeabilization, oxidative stress, and lipid peroxidation within 24 hours of exposure. During this period, BEAS-2B underwent epithelial-to-mesenchymal transition (EMT), including loss of epithelial cell morphology, decreased E-cadherin expression, and increased α-smooth muscle actin (α-SMA) and collagen I production. Similar results were observed in neonatal air-liquid interface culture (i.e., disruption of epithelial integrity and EMT). Acute exposure of infant mice to DCB-230 resulted in EMT, as confirmed by lineage tracing studies and evidenced by coexpression of epithelial E-cadherin and mesenchymal α-SMA proteins in airway cells and increased SNAI1 expression in the lungs. EMT in neonatal mouse lungs after EPFR exposure may provide an explanation for epidemiological evidence supporting PM exposure and increased risk of asthma. Copyright © 2013 by the American Thoracic Society

    Diamond-Based Thin Film Bulk Acoustic Wave Resonator for Biomedical Applications

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    Nowadays it is in constant growing the development of thin film bulk acoustic resonators. If the piezoelectric material is going to be implanted in the human body, an important requirement is the biocompatibility of the implant. In this regard, Aluminum Nitride (AlN) has emerged as an attractive alternative for use in biomedical MicroElectroMechanical Systems. Ultrananocrystalline Diamond (UNCD) is a promising material to be used in biomedical applications, due to its extraordinary mulifunctionality; it is exceptional for implantable medical devices requiring stringent biological performance. Since both UNCD and AlN films can be processed via photolithography processes used in microfabrication, the integration of UNCD and AlN films provides the bases for developing a new generation of biocompatible Bio-MEMS/NEMS. Research and development was conducted to produce implantable MEMS devices: Pt/piezoelectric AlN/Pt layer heterostructure was grown and patterned on the UNCD membrane with a Ti adhesion layer. By applying voltages between the top and bottom Pt electrodes layers the piezoelectric AlN layer is energized. The feasibility of the fabrication of biocompatible AlN/diamond-based FBAR structure has been demonstrated.Fil: Zalazar, Martin. Universidad Nacional de Entre Rios. Facultad de Ingenieria. Departamento de Bioingenieria; ArgentinaFil: Guarnieri, Fabio Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico. Centro de Investigación de Métodos Computacionales; Argentina. Universidad Nacional de Entre Rios. Facultad de Ingenieria. Departamento de Bioingenieria; Argentin

    Regulatory T Cells in the Pathogenesis and Healing of Chronic Human Dermal Leishmaniasis Caused by Leishmania (Viannia) Species

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    The immune inflammatory response is a double edged sword. During infectious diseases, regulatory T cells can prevent eradication of the pathogen but can also limit inflammation and tissue damage. We investigated the role of regulatory T cells in chronic dermal leishmaniasis caused by species of the parasite Leishmania that are endemic in South and Central America. We found that although individuals with chronic lesions have increased regulatory T cells in their blood and at skin sites where immune responses to Leishmania were taking place compared to infected individuals who do not develop disease, their capacity to control the inflammatory response to Leishmania was inferior. However, healing of chronic lesions at the end of treatment was accompanied by an increase in the number and capacity of regulatory T cells to inhibit the function of effector T cells that mediate the inflammatory response. Different subsets of regulatory T cells, defined by the expression of molecular markers, were identified during chronic disease and healing, supporting the participation of distinct regulatory T cells in the development of disease and the control of inflammation during the healing response. Immunotherapeutic strategies may allow these regulatory T cell subsets to be mobilized or mitigated to achieve healing

    Consequences of local gauge symmetry in empirical tight-binding theory

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    A method for incorporating electromagnetic fields into empirical tight-binding theory is derived from the principle of local gauge symmetry. Gauge invariance is shown to be incompatible with empirical tight-binding theory unless a representation exists in which the coordinate operator is diagonal. The present approach takes this basis as fundamental and uses group theory to construct symmetrized linear combinations of discrete coordinate eigenkets. This produces orthogonal atomic-like "orbitals" that may be used as a tight-binding basis. The coordinate matrix in the latter basis includes intra-atomic matrix elements between different orbitals on the same atom. Lattice gauge theory is then used to define discrete electromagnetic fields and their interaction with electrons. Local gauge symmetry is shown to impose strong restrictions limiting the range of the Hamiltonian in the coordinate basis. The theory is applied to the semiconductors Ge and Si, for which it is shown that a basis of 15 orbitals per atom provides a satisfactory description of the valence bands and the lowest conduction bands. Calculations of the dielectric function demonstrate that this model yields an accurate joint density of states, but underestimates the oscillator strength by about 20% in comparison to a nonlocal empirical pseudopotential calculation.Comment: 23 pages, 7 figures, RevTeX4; submitted to Phys. Rev.
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