Aplicación empírica de metodologías de Machine Learning to Rank. Comparación con otras técnicas de aprendizaje supervisado en diferentes aplicaciones

Existen muchos problemas de negocio que requieren predecir u ordenar un conjunto de opciones. Para resolver este tipo de preguntas los modelos tradicionales de aprendizaje supervisado pueden no ser ideales, ya que no están diseñados para esta tarea. Learning to Rank, por otro lado, es una rama del aprendizaje supervisado que busca ordenar un conjunto de opciones dado un criterio de relevancia. En esta tesis se evalúa el desempeño de estos modelos en tres aplicaciones diferentes. Dos de ellas requieren ordenar páginas web respecto a criterios de búsqueda, y la tercera es un sistema de recomendación de productos en un marketplace. Los resultados obtenidos en este estudio sugieren que estos modelos tienen un mejor desempeño en tareas de ordenamiento que técnicas tradicionales de regresión y clasificación. Utilizar Learning to Rank con la metodología planteada en esta tesis, puede ayudar a industrias de diferentes tipos a obtener mejores resultados en múltiples áreas como marketing y finanzas

Resultados del tratamiento quirúrgico de los aneurismas de aorta abdominal infrarrenal

Introduction: Surgical treatment outcomes for infrarenal abdominal aortic aneurysm repair depend on patient factors and attending vascular team expertise. Objetives: To describe the outcomes of surgical treatment of abdominal aortic aneurysm performed by an interdisciplinary team and to evaluate the effects of annual caseload and acquired expertise. Methods: Historic cohort of patients with abdominal aortic aneurysm diagnosis surgically trea-ted from January 1994 to June 2013. Three groups were established: Group 1 was for openruptured abdominal aortic aneurysm repair, Group 2 was for open elective repair and Group 3 was for elective endovascular aneurysm repairs. Primary outcome was in-hospital mortality, andsecondary outcomes were peri-procedural morbidity. For analysis the cohort was divided in two: cases repaired from 1994 to 2002 and from 2002 to 2013. This was based in the implementation of endovascular therapy from 2002 at the institution.Results: 573 patients were treated; Group 1: 65 patients; Group 2: 433 patients; Group 3: 75 patients. Mortality was 28.6%, 2.8% and 1.3% respectively. A significant rise in annual case-load (233%) was demonstrated and a trend toward lowering in surgical mortality (4.8 vs. 2.0%,p = 0.19) after 2002. Conclusions: Implementation of endovascular repair has contributed to rising annual caseloadof patients with abdominal aortic aneurysm at our institution. This rising in volume correlateswith effective lowering in mortality. © 2015 Sociedad Colombiana de Cardiología y Cirugía Cardiovascular

Intervención psiquiátrica en programa de trasplantes

ResumenEn los últimos años la Psiquiatría de Enlace e Interconsulta ha experimentado un salto cualitativo, acercándose al espacio común del resto de las especialidades médicas: el hospital general. La participación de psiquiatras en programas clínicos específicos como las unidades de trasplantes de órganos sólidos tiene fundamentaciones técnicas precisas dada la correlación entre síntomas psíquicos y las características clínicas específicas de las enfermedades médicas que requieren de este procedimiento. Cada vez hay una mayor preocupación en los clínicos y cirujanos en relación a los factores psíquicos que obstaculizan la adherencia a los tratamientos e indicaciones médicas tanto antes como después de efectuado el trasplante. La población de pacientes pre y post-trasplantados exhiben elevadas tasas de cuadros psiquiátricos específicos que ameritan un tratamiento coordinado multidisciplinario. El objetivo de este trabajo es mostrar la experiencia inicial que estamos desarrollando en la Unidad de Trasplantes de Clínica Las Condes.SummaryIn recent years consultation-liaison psychiatry has experienced a quantum leap closer to the common space of the other medical specialties: the general hospital. The participation in clinical programs such as the units of solid organ transplants have required technical arguments given the correlation between psychiatric symptoms and the clinical features of specific medical illness that require this procedure. During the last time, there have been and increasingly concern among clinicians and surgeons in regard to the psychological factors that affect the adherence to treatment and medical advice before and after transplant. The population concerning pre and post transplantation issues, exhibits significant rates of specifics psychiatric disorders which require evaluation and drug treatment specialist coordination. The aim of this paper is to show the initial experience we have developed in the transplant unit of Clínica Las Condes, concerning psychiatric and psychosocial issues

Factores asociados a insuficiencia renal postoperatoria en cirugía de revascularización miocárdica

Motivation: To determine which medical history and surgical procedure factors are associated to the onset of postoperative kidney failure in patients undergoing myocardial revascularisation. Methods: Case-control cohort study carried out between January 2005 and December 2013 which included patients who had undergone elective myocardial revascularisation and showed postoperative kidney failure immediately after surgery and until discharge. Controls consisted of patients who had undergone elective myocardial revascularisation and did not develop postoperative kidney failure immediately after surgery. A logistic regression model was used to determine the factors associated to postoperative kidney failure. Associations were expressed as grounds of disparity with their corresponding confidence intervals. Results: old age [OR 1.03 CI 95% (1.01-1.04)], preoperative presence of diabetes mellitus [OR 1.8 CI 95% (1.9-3.4)], cardiac insufficiency [OR 2.7 CI 95% (1.1-6.7)] and a longer perfusion time [OR 1.02 CI 95% (1.01-1.03)] were associated to a higher risk of postoperative kidney failure, while higher hematocrit [OR 0.86 CI 95% (0.82-0.91)] and higher ejection fraction [OR 0.94 CI 95% (0.92-0.96)] were associated with a decrease of the risk of postoperative kidney failure. Conclusions: In patients who had undergone myocardial revascularisation, risk factors associated to postoperative kidney failure where comorbidities related to internal and external gradual kidney damage outside the context of the surgery. This implies that strategies to minimise this event should be focused on identifying these patients in a timely manner and offering appropriate nephroprotection. © 2015 Sociedad Colombiana de Cardiología y Cirugía Cardiovascular

Fijador externo acrílico con tornillos percutáneos para el tratamiento de fracturas de huesos largos en perros miniatura

La utilización de un fijador externo híbrido, a base de tornillos corticales percutáneos unidos con una barra conectora de material acrílico que incorpora las cabezas de los tornillos, permite tratar eficazmente fracturas de huesos largos, especialmente radio y tibia, en perros miniatura, minimizando el riesgo de complicaciones como la isquemia ósea o la protección frente al estrés.

Genetically Modifying the Insect Gut Microbiota to Control Chagas Disease Vectors through Systemic RNAi

Technologies based on RNA interference may be used for insect control. Sustainable strategies are needed to control vectors of Chagas disease such as Rhodnius prolixus. The insect microbiota can be modified to deliver molecules to the gut. Here, Escherichia coli HT115(DE3) expressing dsRNA for the Rhodnius heme-binding protein (RHBP) and for catalase (CAT) were fed to nymphs and adult triatomine stages. RHBP is an egg protein and CAT is an antioxidant enzyme expressed in all tissues by all developmental stages. The RNA interference effect was systemic and temporal. Concentrations of E. coli HT115(DE3) above 3.35 × 107 CFU/mL produced a significant RHBP and CAT gene knockdown in nymphs and adults. RHBP expression in the fat body was reduced by 99% three days after feeding, returning to normal levels 10 days after feeding. CAT expression was reduced by 99% and 96% in the ovary and the posterior midgut, respectively, five days after ingestion. Mortality rates increased by 24-30% in first instars fed RHBP and CAT bacteria. Molting rates were reduced by 100% in first instars and 80% in third instars fed bacteria producing RHBP or CAT dsRNA. Oviposition was reduced by 43% (RHBP) and 84% (CAT). Embryogenesis was arrested in 16% (RHBP) and 20% (CAT) of laid eggs. Feeding females 105 CFU/mL of the natural symbiont, Rhodococcus rhodnii, transformed to express RHBP-specific hairpin RNA reduced RHBP expression by 89% and reduced oviposition. Modifying the insect microbiota to induce systemic RNAi in R. prolixus may result in a paratransgenic strategy for sustainable vector control

Bispecific PD1-IL2v and anti-PD-L1 break tumor immunity resistance by enhancing stem-like tumor-reactive CD8⁺ T cells and reprogramming macrophages.

Immunotherapies have shown remarkable, albeit tumor-selective, therapeutic benefits in the clinic. Most patients respond transiently at best, highlighting the importance of understanding mechanisms underlying resistance. Herein, we evaluated the effects of the engineered immunocytokine PD1-IL2v in a mouse model of de novo pancreatic neuroendocrine cancer that is resistant to checkpoint and other immunotherapies. PD1-IL2v utilizes anti-PD-1 as a targeting moiety fused to an immuno-stimulatory IL-2 cytokine variant (IL2v) to precisely deliver IL2v to PD-1 <sup>+</sup> T cells in the tumor microenvironment. PD1-IL2v elicited substantial infiltration by stem-like CD8 <sup>+</sup> T cells, resulting in tumor regression and enhanced survival in mice. Combining anti-PD-L1 with PD1-IL2v sustained the response phase, improving therapeutic efficacy both by reprogramming immunosuppressive tumor-associated macrophages and enhancing T cell receptor (TCR) immune repertoire diversity. These data provide a rationale for clinical trials to evaluate the combination therapy of PD1-IL2v and anti-PD-L1, particularly in immunotherapy-resistant tumors infiltrated with PD-1 <sup>+</sup> stem-like T cells

Oferta de vegetales y frutas en la alimentación escolar a partir de la adquisición local de alimentos: el caso de un municipio brasileño

Antecedentes/Objetivos: Los Programas de Alimentación Escolar (PAE) vinculados a la adquisición de alimentos locales se consideran estratégicos para la promoción de la Seguridad Alimentaria y Nutricional. En el año 2009 el gobierno brasileño implementó una legislación nacional para el PAE que hace obligatoria la adquisición local de alimentos de la agricultura familiar. El objetivo de esta investigación fue evaluar el impacto de la adquisición local de alimentos de la agricultura familiar en la oferta de vegetales y frutas en la alimentación escolar en un municipio de Santa Catarina/Brasil. Métodos: Estudio cuasi experimental, donde se analizaron las cantidades per cápita (kilogramo/alumno/año) y las variedades (n) de frutas y vegetales adquiridas en dos años anteriores (2008/2009) y dos posteriores (2010/2011) a la implementación de la actual legislación del programa. Se realizó un análisis descriptivo. Resultados: Los resultados muestran una reducción progresiva en la cantidad per cápita anual de frutas en los años analizados: 7 kg (2008); 5,8 kg (2009); 5,5 kg (2010) 4,4 kg (2011), con una tasa de variación de –37% en relación a 2008. Respecto a la variedad de las frutas, fueron adquiridas 6 en 2008, 2009 y 2010 y 5 en 2011. En 2010 y 2011, la agricultura familiar suministró 2 y 1 variedad respectivamente. En los vegetales se observó reducción en la cantidad en los dos primeros años y aumento en los dos posteriores: 1,9 kg (2008); 1,8 kg (2009); 2,9 kg (2010); 3,05 kg (2011), con una tasa de variación de 60% en relación a 2008. Además se observó un aumento en la variedad: 7 (2008), 6 (2009) y 11 (2010/2011), que puede atribuirse a la adquisición de alimentos de la agricultura familiar, ya que aportó 7 de las variedades en 2010 y 2011. Conclusiones: Aunque la legislación del programa parece no revertir la reducción en la adquisición de frutas del período estudiado, se evidencia un incremento de la cantidad y variedad de vegetales que redundan en la mejora de la calidad alimentaria. Estos resultados sugieren que la adquisición de alimentos locales influye positivamente en la alimentación escolar.Convocatoria MCT/MDS/SAGI/CNPq Nº36/2010

Centralized Modularity of N-Linked Glycosylation Pathways in Mammalian Cells

Glycosylation is a highly complex process to produce a diverse repertoire of cellular glycans that are attached to proteins and lipids. Glycans are involved in fundamental biological processes, including protein folding and clearance, cell proliferation and apoptosis, development, immune responses, and pathogenesis. One of the major types of glycans, N-linked glycans, is formed by sequential attachments of monosaccharides to proteins by a limited number of enzymes. Many of these enzymes can accept multiple N-linked glycans as substrates, thereby generating a large number of glycan intermediates and their intermingled pathways. Motivated by the quantitative methods developed in complex network research, we investigated the large-scale organization of such N-linked glycosylation pathways in mammalian cells. The N-linked glycosylation pathways are extremely modular, and are composed of cohesive topological modules that directly branch from a common upstream pathway of glycan synthesis. This unique structural property allows the glycan production between modules to be controlled by the upstream region. Although the enzymes act on multiple glycan substrates, indicating cross-talk between modules, the impact of the cross-talk on the module-specific enhancement of glycan synthesis may be confined within a moderate range by transcription-level control. The findings of the present study provide experimentally-testable predictions for glycosylation processes, and may be applicable to therapeutic glycoprotein engineering