Universidad del Desarrollo

About: Universidad del Desarrollo is a education organization based out in Santiago, Chile. It is known for research contribution in the topics: Population & Entrepreneurship. The organization has 2695 authors who have published 3578 publications receiving 52302 citations.

Tracheostomy Tube Placement: Early and Late Complications.

Abstract: Tracheostomy tube placement is a therapeutic procedure that has gained increased favor over the past decade. Upper airway obstructions, failure to liberate from the ventilator, and debilitating neurological conditions are only a few indications for tracheostomy tube placement. Tracheostomy tubes can be placed either surgically or percutaneously. A percutaneous approach offers fewer surgical site infections and postsurgical bleeding than a surgical approach. A surgical placement posses a lower risk of injury to the posterior tracheal wall and spontaneous decannulation is less common. Late complications of both approaches include stenosis, malacia, along with tracheoesophageal, tracheoinnominate, and tracheocutaneous fistulas. This review describes the indications and methods of placement of tracheostomy tubes along with early and late complications that may occur following placement.

Intravitreal administration of multipotent mesenchymal stromal cells triggers a cytoprotective microenvironment in the retina of diabetic mice.

Abstract: Diabetic retinopathy is a common complication of diabetes and the leading cause of irreversible vision loss in the Western world. The reduction in color/contrast sensitivity due to the loss of neural cells in the ganglion cell layer of the retina is an early event in the onset of diabetic retinopathy. Multipotent mesenchymal stromal cells (MSCs) are an attractive tool for the treatment of neurodegenerative diseases, since they could differentiate into neuronal cells, produce high levels of neurotrophic factors and reduce oxidative stress. Our aim was to determine whether the intravitreal administration of adipose-derived MSCs was able to prevent the loss of retinal ganglion cells in diabetic mice. Diabetes was induced in C57BL6 mice by the administration of streptozotocin. When retinal pro-damage mechanisms were present, animals received a single intravitreal dose of 2 × 105 adipose-derived MSCs or the vehicle. Four and 12 weeks later we evaluated: (a) retinal ganglion cell number (immunofluorescence); (b) neurotrophic factor levels (real-time quantitative polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA)); (c) retinal apoptotic rate (TUNEL); (d) retinal levels of reactive oxygen species and oxidative damage (ELISA); (e) electrical response of the retina (electroretinography); (f) pro-angiogenic and anti-angiogenic factor levels (RT-qPCR and ELISA); and (g) retinal blood vessels (angiography). Furthermore, 1, 4, 8 and 12 weeks post-MSC administration, the presence of donor cells in the retina and their differentiation into neural and perivascular-like cells were assessed (immunofluorescence and flow cytometry). MSC administration completely prevented retinal ganglion cell loss. Donor cells remained in the vitreous cavity and did not differentiate into neural or perivascular-like cells. Nevertheless, they increased the intraocular levels of several potent neurotrophic factors (nerve growth factor, basic fibroblast growth factor and glial cell line-derived neurotrophic factor) and reduced the oxidative damage in the retina. Additionally, MSC administration has a neutral effect on the electrical response of the retina and did not result in a pathological neovascularization. Intravitreal administration of adipose-derived MSCs triggers an effective cytoprotective microenvironment in the retina of diabetic mice. Thus, MSCs represent an interesting tool in order to prevent diabetic retinopathy.

Head Position and Cerebral Blood Flow Velocity in Acute Ischemic Stroke: A Systematic Review and Meta-Analysis

Abstract: Background: Patients with acute ischemic stroke (AIS) have impaired vasomotor reactivity, especially in the affected cerebral hemisphere, such that they may depend directly on systemic blood pressure to maintain perfusion to vulnerable ‘at risk' penumbral tissue. As the sitting up position may affect cerebral perfusion by decreasing cerebral blood flow (CBF) in salvageable tissue, positioning AIS patients with their head in a lying flat position could increase CBF through collateral circulation or gravitational force. We wished to quantify the effect of different head positions on mean flow velocity (MFV) by transcranial Doppler ultrasonography (TCD) in AIS patients to assess the potential for benefit (or harm) of head positioning in a clinical trial. Methods: We performed a systematic review and meta-analysis of observational studies with TCD to evaluate differences in cerebral MFV between the lying flat and sitting up head positions in AIS. For each study and each comparison, we obtained the mean value of changes in MFV and its variance. Results: A total of 303 studies were identified, but 298 were excluded for varying reasons; 4 papers met the inclusion criteria and 57 patients were included in the meta-analysis for calculation of the overall mean difference in MFV. We found a significant increase in MFV from a bed angle of 30 to 15° (4.6 cm/s, 95% confidence interval, CI, 2.9-6.2, p Conclusions: In AIS patients, MFV increased significantly in the side affected by the stroke but not in the unaffected side when they were positioned in a lying flat head position at 0 or 15° compared to an upright head position at 30°. The clinical significance of these findings is now undergoing further randomized evaluation in the international multicenter Head Position in Acute Stroke Trial (HeadPoST).

Reverberation Mapping of Luminous Quasars at High z

Abstract: We present Reverberation Mapping (RM) results for 17 high-redshift, high-luminosity quasars with good quality R-band and emission line light curves. We are able to measure statistically significant lags for Lyα (11 objects), SiIV (5 objects), CIV (11 objects), and CIII] (2 objects). Using our results and previous lag determinations taken from the literature, we present an updated CIV radius– luminosity relation and provide for the first time radius–luminosity relations for Lyα, SiIV and CIII]. While in all cases the slope of the correlations are statistically significant, the zero points are poorly constrained because of the lack of data at the low luminosity end. We find that the emissivity weighted distance from the central source of the Lyα, SiIV and CIII] line emitting regions are all similar, which corresponds to about half that of the Hβ region. We also find that 3/17 of our sources show an unexpected behavior in some emission lines, two in the Lyα light curve and one in the SiIV light curve, in that they do not seem to follow the variability of the UV continuum. Finally, we compute RM black hole masses for those quasars with highly significant lag measurements and compare them with CIV single–epoch (SE) mass determinations. We find that the RM-based black hole mass determinations seem smaller than those found using SE calibrations. Subject headings: galaxies: active — surveys — variability