Improving the binding capacity of Ni2+ decorated porous magnetic silica spheres for histidine-rich protein separation.

Biomagnetic immobilization of histidine-rich proteins based on the single-step affinity adsorption of transition metal ions continues to be a suitable practice as a cost effective and a up scaled alternative to the to multiple-step chromatographic separations. In our previous work, we synthesised Porous Magnetic silica (PMS) spheres by one-step hydrothermal-assisted modified-stöber method. The obtained spheres were decorated with Ni(2+) and Co(2+), and evaluated for the capture of a H6-Tagged green fluorescence protein (GFP-H6) protein. The binding capacity of the obtained spheres was found to be slightly higher in the case Ni(2+) decorated PMS spheres (PMSNi). However, comparing with commercial products, the binding capacity was found to be lower than the expected. In this way, the present work is an attempt to improve the binding capacity of PMSNi to histidine-rich proteins. We find that increasing the amount of Ni(2+) onto the surface of the PMS spheres leads to an increment of the binding capacity to GFP-H6 by a factor of two. On the other hand, we explore how the size of histidine-rich protein can affect the binding capacity comparing the results of the GFP-6H to those of the His-tagged α-galactosidase (α-GLA). Finally, we demonstrate that the optimization of the magnetophoresis parameters during washing and eluting steps can lead to an additional improvement of the binding capacity.

Design and characterization of Ni2+ and Co2+ decorated Porous Magnetic Silica spheres synthesized by hydrothermal-assisted modified-Stöber method for His-tagged proteins separation.

The complete elimination of enzymes from the reaction mixture and the possibility of its recycling for several rounds result in great benefits, allowing the reduction of the enzyme consumption and their usability in continuous processes. In this work, it is evaluated the capture of a H6-tagged green fluorescence protein (GFP-H6) on porous magnetic spheres using the Co(2+) and Ni(2+) affinity adsorption as a possible cost-effective and up-scaled alternative way for the immobilization of His-tagged proteins. For this purpose, Porous Magnetic Silica (PMS) spheres were synthesized by one-step hydrothermal-assisted modified-Stöber method. The obtained spheres have a homogenous size distribution of 400 nm diameter. The γ-Fe(2)O(3) nanoparticles are homogenously distributed in the silica matrix. The obtained PMS spheres have a saturation magnetization of about 10 emu/g. Magnetophoresis measurements show a total separation time of 16 min at 60 T/m. The obtained PMS spheres were successfully and homogenously decorated with Co(2+) and Ni(2+) and then evaluated for the capture of a GFP-H6 protein. The results were compared with the performance of the commercial beads Dynabeads® His-Tag Isolation & Pulldown.

Simple analytical model for the magnetophoretic separation of superparamagnetic dispersions in a uniform magnetic gradient.

Magnetophoresis--the motion of magnetic particles under applied magnetic gradient--is a process of great interest in novel applications of magnetic nanoparticles and colloids. In general, there are two main different types of magnetophoresis processes: cooperative magnetophoresis (a fast process enhanced by particle-particle interactions) and noncooperative magnetophoresis (driven by the motion of individual particles in magnetic fields). In the case of noncooperative magnetophoresis, we have obtained a simple analytical solution which allows the prediction of the magnetophoresis kinetics from particle characterization data (size and magnetization). Our comparison with new experimental results shows good quantitative agreement. In addition, we show the existence of a universal curve onto which all experimental results should collapse after proper rescaling. The range of applicability of the analytical solution is discussed in light of the predictions of a magnetic aggregation model [Soft Matter 7, 2336 (2011)].

Resultados de un programa de cirugía mayor ambulatoria en oftalmología / Results an outpatient major surgery program in ophthalmology

Objetivo: Evaluar los resultados de un programa de cirugía mayor ambulatoria en pacientes intervenidos quirúrgicamente de diversas patologías oculares en nuestro hospital. Métodos: Este estudio retrospectivo incluye 13.878 pacientes intervenidos de forma programada por el Servicio de Oftalmología desde septiembre de 1998 a diciembre de 2004. En 11.187 pacientes se realizaron diferentes procedimientos quirúrgicos de forma ambulatoria, siendo la cirugía de catarata (facoemulsificación) la operación mayoritaria (8.155 casos). Se han analizado diversos índices (sustitución, suspensión, ingresos, reingresos), así como el rendimiento quirúrgico y las complicaciones sistémicas y oculares que surgieron dentro de las primeras 72 horas tras la cirugía. La medición de las variables se realizó mediante frecuencias relativas. El análisis utilizado para la evolución de las complicaciones en el período de estudio fue la Chi cuadrado de tendencias. Resultados: 13.878 pacientes fueron intervenidos en el período indicado, de los que 11.187 se operaron de forma ambulatoria (índice de sustitución global del 80,6%). El rendimiento quirúrgico medio fue 74,36%. El índice de ingresos tras la cirugía fue 4,46% (499 pacientes), siendo ingresos inmediatos en el 92,18% de los casos (460). 21 pacientes sufrieron complicaciones graves (cardiovasculares, neurológicas, metabólicas, infecciosas), representando un riesgo proporcional de 1:532. En 45 pacientes aparecieron complicaciones de menor gravedad (hipertensión arterial, nauseas, vómitos, síncope vasovagal) que requirieron su ingreso hospitalario. Las complicaciones oftalmológicas ocurrieron en 79 casos (0,56%). Conclusiones: La cirugía mayor ambulatoria (CMA) es un excelente modelo organizativo de asistencia quirúrgica multidisciplinar que permite tratar pacientes bien seleccionados de una manera efectiva, segura y eficiente. A pesar del cumplimiento de los requisitos óptimos, existe un porcentaje pequeño de complicaciones postoperatorias de gravedad variable, aunque afortunadamente la mortalidad es prácticamente nula

Purpose: To evaluate the outcomes in our hospital of an ambulatory major surgery program in patients with a variety of different ocular pathologies. Method: This retrospective study includes 13,878 patients who underwent programmed surgery by the Department of Ophthalmology between September 1998 and December 2004. Different ophthalmological surgical procedures were performed as outpatient surgery in 11,187 patients, with cataract surgery (phacoemulsification) being the most frequent operation performed (8,155 cases). We have analysed several indicators (substitution, suspension, admission and readmission rates), as well as surgical yield and systemic and ocular complications which appeared within 72 hours after surgery. The variables were measured as relative frequencies. The evolution of complications during the study period was analysed by the Chi-square trend test. Results: 13,878 patients had ophthalmic surgery during the study period; 11,187 had outpatient surgery with a global substitution ratio of 80.6%. The median surgical yield was 74.36%. The admission rate after surgery was 4.46% (499 patients), with 92.18% (460) of these requiring immediate admission. Twenty-one patients suffered from severe complications (cardiovascular, neurological, metabolic, infectious), representing a proportional risk of 1:532. Forty-five patients had less severe complications (arterial hypertension, nausea, vomiting, vasovagal syncope) that required admission to hospital. Ophthalmologic complications occurred in 79 cases (0.56%). Conclusions: Ambulatory major surgery (AMS) is an excellent organization model of multidisciplinary surgical assistance that makes it possible to treat well selected patients in an effective, safe and efficient manner. There is a low incidence of postoperative complications of variable severity despite following the optimum requisites, although fortunately mortality is practically absent

Experiencia de siete años e indicadores de calidad en una unidad de cirugía mayor ambulatoria / Seven years experience and quality indicators in ambulatory surgery

La cirugía mayor ambulatoria ha experimentado un espectacular incremento en nuestro país en la última década. Su objetivo final es conseguir resultados equivalentes a la cirugía tradicional, con menores costes, y con un grado de satisfacción de los usuarios igual o mayor. MATERIAL Y METODOS: Estudio retrospectivo en una unidad de cirugía mayor ambulatoria tipo II. El período de estudio abarca a los años 1997-2003, recogiéndose los principales indicadores de calidad para este tipo de cirugía. El registro de la actividad quirúrgica se realiza de acuerdo al PLAN HP HISS integrado en la gestión de la lista de espera quirúrgica. RESULTADO: En el período de estudio se intervienen 50573 pacientes en la Unidad de cirugía. De ellos, de forma programada y con criterios de selección para cirugía mayor ambulatoria se realiza 27307 procedimientos. Los indicadores de calidad propuestos y sus resultados globales son: Índice de sustitución (53,99%), Índice de Ingresos (7,10%), Índice de Reingresos (0,86%), Consultas a Servicios de Urgencias sin ingreso (2,07%), Índice de Suspensión (8,01%). CONCLUSIONES: La implantación y asentamiento de nuestra unidad de cirugía ambulatoria ha sido progresiva. Actualmente más del 50% de las intervenciones programadas se realizan en régimen ambulatorio (índice de sustitución del 53,99%), sin embargo el índice de ingresos y suspensiones es demasiado elevado, debiendo dirigirse los planes de mejora de calidad de la unidad a estos índices (AU)

INTRODUCTION: Ambulatory surgery has experienced an enormous increase in Spain in the last decade. Its final goal is to achieve results equivalent to those obtained in traditional surgery, at lower costs and with the same or higher patients´level of satisfaction. MATERIAL AND METHODS: A retrospective study in ambulatory surgical type II Unit. The study period is from 1997 to 2003, when the main quality indicators for this kind of surgery were established. Surgical activity is registered according to HP HISS PLAN, which is included in the management of the surgical waiting list. RESULTS: During this period, a total of 50,573 patients were operated on in the Surgical Unit, 27,307 of which were schedule and operated on following the selection criteria for ambulatory surgery. These are the proposed quality indicators and the global results: substitution index (53.99%), admission index (7.10%), re-admission index (0.86%), Emergency Department consultations without hospital admission (2.07%); cancellation index (8.01%). CONCLUSIONS: The Ambulatory Surgical Unit has been progressively established. Currently more than 50% of the scheduled surgical operations are perfomed in an ambulatory regime (substitution index of 53,99%). However, admission index and cancellation index ae still too high, therefore quality improvement plant for this unit must contemplate these mentioned indexes as a main objective for improvement (AU)