oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 1 )

2019 ( 80 )

2018 ( 96 )

2017 ( 101 )

Custom range...

Search Results: 1 - 10 of 33458 matches for " John Bustamante "
All listed articles are free for downloading (OA Articles)
Page 1 /33458
Display every page Item
Biomecánica de la asistencia cardiocirculatoria
Bustamante,John; Valbuena,Javier;
Insuficiencia card?-aca , 2010,
Abstract: since the transplant as standard procedure for heart failure treatment was established, the few donors' availability turned into biggest limitation in view of the increasing demand. this situation, concomitant with the relevant results obtained with mechanical cardiac-circulatory assist devices (mccad), promoted the use of these devices as an option so much to improve the survive as the quality of life of the patients with advanced heart failure. the medical technology offers nowadays a wide range of mccad, with diverse characteristics and specifications of application. which go from the fixings for percutaneous way up to the surgical one, those of transitory use of shortly up to long term, and those of support to a ventricle up to the definitive substitution of the heart. unfortunately, the advances achieved in the treatment of the heart failure with the mechanical devices have been evaluated only in the physiological environment, leaving of side the biomechanical aspect, for what seems that its therapeutic results not always are successful or are its impediments of application major than the benefits. it is fundamental to do an integral analysis of this cardiac therapy, which includes the biomechanical environment, to understand its functionality and to make use of the potential that these medical devices have showed in the cardiac-circulatory assistance.
Cardioproteómica: perspectivas y retos Cardioproteomics: perspectives and challenges
John Bustamante Osorno,óscar Alzate
Revista Colombiana de Cardiología , 2008,
Abstract:
Evaluación hidromecánica de venas yugulares bovinas frescas y fijadas en glutaraldehído para uso como bioimplante cardiovascular
Bustamante,John; Echeverri,Claudia E; Valbuena,Javier;
Revista Colombiana de Cardiología , 2007,
Abstract: many congenital heart diseases may be treated surgically with biological or artificial implants that will allow the restoration of cardiovascular system functionality. due to its properties, the biologic implants obtained from dead donors (homografts) are the most appropriate for ventricular output reconstructive surgeries. unfortunately, these are difficult to acquire, because they are obtained from newborn donors and may be correlated to the dimensions and geometry of the native structure to be repaired. this project evaluated the hydrodynamic behavior of valvular segments of bovine jugular veins (obtained from the livestock central in medellin), mounting the venous segment on a test bank that simulated the right ventricle output tract and the pulmonary trunk, in order to analyze its behavior in similar conditions to those that the vessel must face as bio-implant in the correction of congenital cardiovascular alterations in newborns and infants.
Evaluación hidromecánica de venas yugulares bovinas frescas y fijadas en glutaraldehído para uso como bioimplante cardiovascular Hydromechanical evaluation of bovine jugular veins fixed in glutaldehyde for its use as cardiovascular implant
John Bustamante,Claudia E Echeverri,Javier Valbuena
Revista Colombiana de Cardiología , 2007,
Abstract: Muchas de las enfermedades cardiovasculares congénitas pueden intervenirse mediante cirugía, con implantes biológicos o artificiales, lo cuales permitirán restablecer la funcionalidad del sistema cardiovascular. Por sus propiedades, los injertos biológicos procedentes de donantes cadavéricos (homoinjertos) son los más apropiados para cirugías reconstructivas del tracto de salida ventricular, pero infortunadamente son difíciles de adquirir ya que se obtienen de donantes con pocas semanas de nacidos, pretendiendo que se correlacionen con las dimensiones y geometría de la estructura nativa a reparar. Con este proyecto se evaluó el comportamiento hidrodinámico de tramos valvulados de venas yugulares bovinas, obtenidas en la Central Ganadera de Medellín, montando el segmento venoso de estudio en un banco de pruebas que emulaba las condiciones del tracto de salida del ventrículo derecho y tronco de la pulmonar, con el fin de analizar su comportamiento en condiciones similares a las que debe afrontar el vaso como bioimplante en la corrección de alteraciones cardiovasculares congénitas en neonatos y ni os. Many congenital heart diseases may be treated surgically with biological or artificial implants that will allow the restoration of cardiovascular system functionality. Due to its properties, the biologic implants obtained from dead donors (homografts) are the most appropriate for ventricular output reconstructive surgeries. Unfortunately, these are difficult to acquire, because they are obtained from newborn donors and may be correlated to the dimensions and geometry of the native structure to be repaired. This project evaluated the hydrodynamic behavior of valvular segments of bovine jugular veins (obtained from the Livestock Central in Medellin), mounting the venous segment on a test bank that simulated the right ventricle output tract and the pulmonary trunk, in order to analyze its behavior in similar conditions to those that the vessel must face as bio-implant in the correction of congenital cardiovascular alterations in newborns and infants.
Theoretically palatable flavor combinations of astrophysical neutrinos
Mauricio Bustamante,John F. Beacom,Walter Winter
Physics , 2015, DOI: 10.1103/PhysRevLett.115.161302
Abstract: The flavor composition of high-energy astrophysical neutrinos can reveal the physics governing their production, propagation, and interaction. The IceCube Collaboration has published the first experimental determination of the ratio of the flux in each flavor to the total. We present, as a theoretical counterpart, new results for the allowed ranges of flavor ratios at Earth for arbitrary flavor ratios in the sources. Our results will allow IceCube to more quickly identify when their data imply standard physics, a general class of new physics with arbitrary (incoherent) combinations of mass eigenstates, or new physics that goes beyond that, e.g., with terms that dominate the Hamiltonian at high energy.
Análisis in vitro de la influencia sobre el campo de flujo de dos modelos de válvulas cardiacas mecánicas bivalvas mediante un túnel de viento
Bustamante O,John; Crispin,Ana I; Escobar,Nelson; Giraldo,Mauricio;
Revista Colombiana de Cardiología , 2011,
Abstract: introduction: prosthetic heart valves are evaluated using different techniques that involve in vitro studies and computational methods in addition to conventional clinical studies. functional data to evaluate reflect the need for highly sensitive methods to determine its operating conditions that may emulate specific hemodynamic situations. with this objective, we designed an alternative method for better understanding the functionality of these models, analyzing in vitro fluid dynamic behavior of two models of mechanical heart valves using a wind tunnel. methods: we designed and developed a wind tunnel providing instrumental conditions that permit the evaluation of mechanical valves in different fluid dynamic conditions: subsonic tunnel of circular section (standard ansi/amca_210-99 and ansi/ashrae_51-99). using the method of dynamic similarity, the experiment was characterized using typical values of flow rates and blood properties in a healthy adult. results and discussion: we evaluated two sjm? valve models, one with flat leaflet, and a variant of convex valves with air flows equivalent to blood flow rates of 1.5, 6.0 and 9.3 l/min. the convex valve prosthesis has a flow divided in three equivalent fields, in contrast to the flat valves that have a smaller central flow and two predominant laterals. the drag phenomenon produced by the two external currents wit regard to the central generates a higher rns for the sjm? valve than the generated for the variant of convex valves. the velocity field adjacent to the convex side is less affected by turbulence than in the case of the flat leaflet, but on the contrary, the adjacent field to the concave side is more affected by local fluid dynamic effects: changes in direction, area reduction and increased velocity. conclusions: the implemented method uses fluid dynamic characteristics of air in a wind tunnel, for in vitro evaluation of the influence on the flow field and shear forces of different models of mechanical heart
Monitor de eventos electrocardiacos implementado en plataforma PDA
Bustamante,John; Sáenz,José F; Amaya,Adrián A;
Revista Colombiana de Cardiología , 2007,
Abstract: ambulatory monitoring of electro-cardiac events constitutes a valuable tool in the diagnosis of cardiac arrhythmias involved in pathologic processes such as myocardiopathies, post-infarction stages, autonomous cardiac system injuries, etc.; unfortunately, its extensive use is not possible yet, due to the high costs that imply the acquisition of these equipments. for this purpose, through the utilization of personal digital assistants, a monitor of cardiac events with pre and post-symptomatic recording capacity, electrocardiographic signal visualization in real time, automatic recording of bradycardias and tachycardias and the possibility of annotation of symptoms by the patient, is designed and developed. it consists of a hardware component for the acquisition and treatment of the signals, a software for the monitoring in palm osò platform and an appliance for the discharge and analysis of the stored data. prototype validations were realized through an electrocardiographic simulator, an arrhythmia simulator based on arrhythmia data base registers of the massachusetts institute of technology and beth israel hospital and on pilot tests of healthy people and of patients with arrhythmias. in this preliminary report, we show the way in which the developed prototype constitutes a viable alternative for ambulatory monitoring of arrhythmia, taking advantages of the storage capacity, processing and visualization that have the actual digital assistances with the additional advantages that its use is not restricted to only one utility and its economic accessibility is facilitated due to its wide commercial availability.
Expresión diferencial de proteínas cardiacas en ratas diabéticas tipo Sprague-Dawley
Southgate,Richard; Osorio,Cristina; Bustamante,John; Alzate,óscar;
Revista Colombiana de Cardiología , 2006,
Abstract: cardiac proteins were isolated from diabetic and wild type sprague-dawley rats, then fractionated by two dimensional gel electrophoresis (2d-page) using isoelectric focusing and molecular weight. the resulting protein spots were stained to facilitate detection. after being converted into a digital image, the proteins on the diabetic and wild type gels were matched to each other then compared to determine levels of expression. sixty of the one hundred and eighty proteins on the gel were removed and digested to produce peptide fragments, which were analyzed by mass spectrometry to determine their amino acid sequence. this information was entered into a protein database (http://www.ncbi.nlm.nih.gov/) to determine the identity of the corresponding proteins. the identity of proteins differentially expressed in cardiac tissue of both groups was determined: several proteins were found to be expressed at different levels than normal in the hearts of diabetic rats, including protein tyrosine phosphatase (ptp, q60998), very low-density lipoprotein receptor (vldl-r, p98156), glutathione peroxidase (phgpx, o70325), serine hydroxymethyl transferase (shmt, p50431), adenylyl cyclase-associated protein 1 (cap1, p40124), and telethonin (telt, o70548).
Análisis in vitro de la influencia sobre el campo de flujo de dos modelos de válvulas cardiacas mecánicas bivalvas mediante un túnel de viento Analysis in vitro of the influence of two mechanical bivalve models of heart valves by a wind tunnel model
John Bustamante O,Ana I Crispin,Nelson Escobar,Mauricio Giraldo
Revista Colombiana de Cardiología , 2011,
Abstract: INTRODUCCIóN: las prótesis valvulares cardiacas se evalúan mediante diferentes técnicas que involucran ensayos in vitro y métodos computacionales, además de los estudios clínicos convencionales. Los datos funcionales a evaluar reflejan la necesidad de contar con métodos de gran sensibilidad para determinar su operación en condiciones que emulen situaciones hemodinámicas específicas. Con este objetivo se proyectó un método alternativo que ayuda a un mejor entendimiento de la funcionalidad de estos dispositivos, analizando el comportamiento fluidodinámico in vitro de dos modelos de válvulas mecánicas cardiacas mediante un túnel de viento. MéTODOS: se dise ó y desarrolló un túnel de viento disponiendo condiciones instrumentales que permitieran evaluar las válvulas mecánicas en distintas situaciones fluidodinámicas: túnel subsónico de sección circular (norma ANSI/AMCA_210-99 y ANSI/ASHRAE_51-99). Empleando el método de similitud dinámica se caracterizó la experimentación utilizando valores típicos de caudales y propiedades de la sangre en un adulto sano. RESULTADOS Y DISCUSIóN: se evaluaron dos modelos valvulares tipo SJM , uno de valvas planas y una variante de valvas convexas, con flujos de aire equivalentes a caudales sanguíneos de 1,5, 6,0 y 9,3 L/min. La prótesis de valvas convexas presenta un flujo dividido en tres campos equivalentes, a diferencia de la de valvas planas que tiene un flujo más peque o en la parte central y dos laterales predominantes. El fenómeno de arrastre producido por las dos corrientes externas con respecto a la central, genera un RNS mayor para la válvula tipo SJM que para la variante con valvas convexas. El campo de velocidad adyacente al lado convexo, se halla menos afectado por la turbulencia que en el caso de la valva plana; pero al contrario, el campo adyacente al lado cóncavo está más afectado por fenómenos fluidodinámicos locales: cambios de dirección, reducción de área y aumento de velocidad. CONCLUSIONES: el método implementado aprovecha las características fluidodinámicas del aire en un banco de pruebas: túnel de viento, para hacer la evaluación in vitro de la influencia sobre el campo de flujo y fuerzas cortantes de diferentes modelos de válvulas cardiacas mecánicas, obteniendo mayor sensibilidad que otras alternativas disponibles. El sistema se usó para evaluar dos tipos de prótesis, mostrando que las valvas curvas tienden a presentar una menor disrupción del flujo que las valvas planas. La implementación del sistema presentado como un nuevo banco de pruebas, permite extraer conclusiones que sirven como base en el di
Desarrollo de un modelo generalizado para realimentación de fuerza y torque en cirugía cardiotorácica robótica mínimamente invasiva: determinación de condiciones y restricciones Development of a generalized model for force and torque feedback in robotic minimally invasive cardiothoracic surgery: identification of conditions and restrictions
Vera Pérez,John Bustamante,Manuel J Betancur,Jairo Espinosa
Revista Colombiana de Cardiología , 2011,
Abstract: INTRODUCCIóN: los procedimientos de cirugía cardiotorácica mínimamente invasiva (MICS, su sigla en Inglés) buscan reducir las complicaciones de las grandes disecciones. No obstante, ante la falta de contacto directo con el tejido por parte del cirujano, éste recibe una sensación parcial de tacto y fuerza, lo que puede originar errores de procedimiento, inadecuada fuerza aplicada al tejido y fatiga durante el acto quirúrgico. La inclusión de dispositivos robóticos con la técnica MICS ha potencializado las habilidades del cirujano para la manipulación de los tejidos, y aunque los desarrollos del mercado no cuentan aún con retroalimentación táctil, se trabaja en prototipos robóticos que incorporan realimentación de fuerza y torque. OBJETIVO: proponer las condiciones y restricciones relacionadas con la incorporación de realimentación de fuerza y torque en MICS robótica, aplicables a diferentes configuraciones de manipuladores, y analizar la implementación de dichas condiciones en un simulador quirúrgico. MATERIAL Y MéTODOS: partiendo del análisis de necesidades durante procedimientos cardiotorácicos y las condiciones de cirugía mínimamente invasiva, se identificaron los requerimientos para garantizar reflexión de fuerza y se realizó un análisis matemático de dichas consideraciones. Finalmente, se verificaron los análisis matemáticos mediante técnicas de modelización y simulación utilizando la plataforma computacional Matlab . RESULTADOS: se argumentaron tres tipos de consideraciones: a) Cinemático: la existencia de un punto fijo, las formas de garantizarlo durante procedimientos MICS robóticos, y las trayectorias de movimiento que el manipulador sigue en aplicaciones de cirugía cardiotorácica; b) Dinámico: la repercusión de fuerzas externas en el manipulador y la manera de considerarlas en el desarrollo de controladores que permitan al cirujano percibir una sensación de contacto con el tejido; c) Sensorial: requerimientos de los sensores de fuerza y relación necesaria entre el número de sensores y actuadores para realimentar fuerza en MICS robótica. Posteriormente se implementaron dichas consideraciones en un simulador y se verificó el cumplimiento de las mismas. CONCLUSIONES: las condiciones relacionadas con la incorporación de un sensor de fuerza y la percepción del cirujano en cuanto al tacto y la fuerza aplicada, resultan ser importantes en procedimientos de MICS robótica y requiere la inclusión de un sistema de control que permita la optimización de procedimientos por telepresencia. INTRODUCTION: the procedures in minimally invasive cardiothoracic surge
Page 1 /33458
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.