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1.
Electrophoresis ; 2024 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-39223919

RESUMEN

The frequency dependence of electrokinetic particle trapping using large-area (>mm2) conductive carbon nanofiber (CNF) mat electrodes is investigated. The fibers provide nanoscale geometric features for the generation of high electric field gradients, which is necessary for particle trapping via dielectrophoresis (DEP). A device was fabricated with an array of microfluidic wells for repeated experiments; each well included a CNF mat electrode opposing an aluminum electrode. Fluorescent microspheres (1 µm) were trapped at various electric field frequencies between 30 kHz and 1 MHz. Digital images of each well were analyzed to quantify particle trapping. DEP trapping by the CNF mats was greater at all tested frequencies than that of the control of no applied field, and the greatest trapping was observed at a frequency of 600 kHz, where electrothermal flow is more significantly weakened than DEP. Theoretical analysis and measured impedance spectra indicate that this result was due to a combination of the frequency dependence of DEP and capacitive behavior of the well-based device.

2.
Retina ; 43(1): 25-33, 2023 01 01.
Artículo en Inglés | MEDLINE | ID: mdl-36542081

RESUMEN

PURPOSE: AR-1105 is a novel biodegradable sustained-release dexamethasone implant designed to deliver 6-month durability. This Phase 2 study evaluated two AR-1105 formulations with different release profiles in patients with macular edema due to retinal vein occlusion. METHODS: Patients received a single intravitreal injection with 340 µg dexamethasone. In the initial phase, five patients received clinical formulation (CF) 1. In the randomized phase, 44 patients were randomized 1:1 to CF1 or CF2. The follow-up was 6 months. Patients had vision loss due to macular edema diagnosed ≥9 (central retinal vein occlusion) or ≥12 months (branch retinal vein occlusion) before screening, and could be treatment-naive or -experienced (if received prior steroids, must have demonstrated response). RESULTS: Both formulations improved vision and reduced retinal thickening from baseline across all visits. At Month 6, mean changes in best-corrected visual acuity were +4.3 and +8.0 letters, and mean changes in central subfield thickness were -93 µm and -211 µm in CF1 and CF2 randomized patients, respectively. Most common adverse events were reduced visual acuity, worsening macular edema, conjunctival hemorrhage, and increased intraocular pressure. No patients required surgery or laser for intraocular pressure control. CONCLUSION: Both formulations were well tolerated and demonstrated clinically meaningful and sustained improvements in vision and retinal thickening in patients with retinal vein occlusion with longstanding edema.


Asunto(s)
Edema Macular , Oclusión de la Vena Retiniana , Humanos , Oclusión de la Vena Retiniana/complicaciones , Oclusión de la Vena Retiniana/diagnóstico , Oclusión de la Vena Retiniana/tratamiento farmacológico , Edema Macular/diagnóstico , Edema Macular/tratamiento farmacológico , Edema Macular/etiología , Dexametasona , Glucocorticoides , Resultado del Tratamiento , Implantes de Medicamentos , Tomografía de Coherencia Óptica , Inyecciones Intravítreas
3.
BMC Public Health ; 23(1): 183, 2023 01 27.
Artículo en Inglés | MEDLINE | ID: mdl-36707792

RESUMEN

Granted by the U.S. Food and Drug Administration, an Emergency Use Authorization (EUA) can only be utilized upon declaration that a specialized set of circumstances exist which justify the authorization. In 2020, the COVID-19 pandemic demanded rapid communication strategies to promote treatment options available through EUA. Despite the authorizations of available monoclonal antibody (mAb) treatments in November 2020, their rate of adoption among health care providers in the U.S. remained low well into 2021. This study examines the accelerators and barriers to provider adoption of COVID-19 treatment so that future adoption of treatments in emerging public health emergencies may be better communicated and hastened. We established a framework informed by adoption accelerators and barriers identified by Diffusion of Innovations (DoI) Theory and conducted a study during the rapidly evolving COVID-19 public health emergency. Most DoI public health research focuses on chronic health issues and has yet to be applied to provider adoption of new treatment under EUA. Through a series of guided interviews with health care providers, primarily physicians or nurse practitioners that were responsible for referring COVID-19 patients, we extracted tools, processes, or other mechanisms (accelerators) and barriers to validate against our DoI framework and fill the gap regarding emergency situations. Our research found that providers supported by large health systems were more inclined to adoption, due to many contributing factors such as the availability of collaborative support and availability of information. Further, communicating evidence-based summaries of treatment options and related processes was also critical to adoption.


Asunto(s)
COVID-19 , Salud Pública , Humanos , COVID-19/epidemiología , Pandemias , Tratamiento Farmacológico de COVID-19 , Personal de Salud
4.
Electrophoresis ; 42(23): 2483-2489, 2021 12.
Artículo en Inglés | MEDLINE | ID: mdl-34409621

RESUMEN

Trapping, sorting, transportation, and manipulation of synthetic microparticles and biological cells enable investigations in their behavior and properties. Microfluidic techniques like rapid electrokinetic patterning (REP) provide a non-invasive means to probe into the nature of these micro and nanoparticles. The opto-electrically induced nature of a REP micro vortex allows tuning of the trap characteristics in real-time. In this work, we studied the effects of transient optical heating on the induced electrothermal vortex using micro-particle image velocimetry (µ-PIV) and computational modeling. A near infra-red (980 nm) laser beam was focused on a colloidal suspension of 1 µm polystyrene beads sandwiched between two parallel-plate electrodes. The electrodes were subjected to an AC current. The laser spot was scanned back-and-forth in a line, at different frequencies, to create the transient vortex. This phenomenon was also studied with a computational model made using COMSOL Multiphysics. We visualize fluid flow in custom-shaped REP traps by superposing multiple axisymmetric (spot) vortices and discuss the limitations of using superposition in dynamically changing traps.


Asunto(s)
Microfluídica , Simulación por Computador , Electrodos , Técnicas Analíticas Microfluídicas , Reología
5.
Scand J Med Sci Sports ; 31(6): 1324-1334, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33560529

RESUMEN

A better insight into injuries in elite-youth football may inform prevention strategies. The purpose of this prospective cohort study was to investigate the frequency, incidence, and pattern of time-loss injuries in an elite male football academy, exploring injuries in relation to age and maturation status. Across four consecutive playing seasons, playing exposure and injuries to all academy players (U'9 to U'21) were recorded by club medical staff. Maturation status at the time of injury was also calculated for players competing in U'13 to U'16 aged squads. Time-loss injury occurrence and maturation status at time of injury were the main outcome measures. A total of 603 time-loss injuries were recorded, from 190 different players. Playing exposure was 229 317 hours resulting in an overall injury rate of 2.4 p/1000 h, ranging from 0.7 p/1000 h (U'11) to 4.8 p/1000 h (U'21). Most injuries were traumatic in mechanism (73%). The most common injury location was the thigh (23%), and the most common injury type was muscle injury (29%) combining to provide the most common injury diagnosis; thigh muscle injury (17%). In U'13-U'16 players, a higher number of injuries to early-maturing players were observed in U'13-U'14 players, while more injuries to U'15-U'16 players occurred when classed as "on-time" in maturity status. Maturation status did not statistically relate to injury pattern; however, knee bone (not-fracture) injuries peaked in U'13 players while hip/groin muscle injuries peaked in U'15 players.


Asunto(s)
Absentismo , Fútbol/lesiones , Deportes Juveniles/lesiones , Adolescente , Factores de Edad , Traumatismos del Tobillo/epidemiología , Atletas , Inglaterra/epidemiología , Ingle/lesiones , Crecimiento/fisiología , Lesiones de la Cadera/epidemiología , Humanos , Incidencia , Puntaje de Gravedad del Traumatismo , Traumatismos de la Rodilla/epidemiología , Masculino , Músculo Esquelético/lesiones , Evaluación de Resultado en la Atención de Salud , Estudios Prospectivos , Rotura/epidemiología , Estaciones del Año , Fútbol/fisiología , Fútbol/estadística & datos numéricos , Esguinces y Distensiones/epidemiología , Estadísticas no Paramétricas , Muslo/lesiones , Factores de Tiempo , Deportes Juveniles/fisiología , Deportes Juveniles/estadística & datos numéricos
6.
Electrophoresis ; 41(1-2): 148-155, 2020 01.
Artículo en Inglés | MEDLINE | ID: mdl-31677287

RESUMEN

Isomotive dielectrophoresis (isoDEP) is a unique DEP geometrical configuration where the gradient of the field-squared ( ∇Erms2 ) is constant. IsoDEP analyzes polarizable particles based on their magnitude and direction of translation. Particle translation is a function of the polarizability of both the particles and suspending medium, the particles' size and shape, and the frequency of the electric field. However, other electrokinetics act on the particles simultaneously, including electrothermal hydrodynamics. Hence, to maximize the DEP force relative to over electrokinetic forces, design parameters such as microchannel geometry, fabrication materials, and applied electric field must be properly tuned. In this work, scaling law analyses were developed to derive design rules, relative to particle diameter, to reduce unwanted electrothermal hydrodynamics relative to DEP-induced particle translation. For a particle suspended in 10 mS/m media, if the channel width and height are below ten particle diameters, the electrothermal-driven flow is reduced by ∼500 times compared to a channel that is 250 particles diameters in width and height. Replacing glass with silicon as the device's underlying substrate for an insulative-based isoDEP reduces the electrothermal induced flow approximately 20 times less.


Asunto(s)
Electroforesis/instrumentación , Hidrodinámica , Técnicas Analíticas Microfluídicas/instrumentación , Termodinámica , Diseño de Equipo , Microelectrodos , Silicio/química
7.
Anal Bioanal Chem ; 412(16): 3813-3833, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32296904

RESUMEN

Isomotive dielectrophoresis (isoDEP) is a unique electric field such that the gradient of the field-squared ([Formula: see text]) is constant, resulting a uniform dielectrophoretic force. The current status of isoDEP is presented in this review, and we will highlight the progress that has been achieved over the past 60 years in various avenues of isoDEP since H.A. Pohl initially described its premise. This article will discuss its applications and describe the various configurations of generating an isomotive force. Since H.A. Pohl introduced the theory of isoDEP, numerous authors have implemented isoDEP as a tool for the manipulation, sorting, separation, and characterization of polarizable particles without the need for biochemical labels or other bioengineered tagging. The growing field of microfluidics and electrokinetics has renewed interest in isoDEP, particularly for analytical characterization or separation of particles. Recent work has demonstrated that isoDEP can address some unmet needs for biomedical applications including single-cell analysis; moreover, advances in throughput as well as combining characterization and separation simultaneously will add significant value to isoDEP.


Asunto(s)
Separación Celular/métodos , Electroforesis/métodos , Diseño de Equipo
8.
Am J Transplant ; 19(3): 831-843, 2019 03.
Artículo en Inglés | MEDLINE | ID: mdl-30203908

RESUMEN

Human islet isolation from young donor pancreases (YDP) utilizing the current purified standard dose of collagenase-protease enzyme mixtures often results in the release of a high percentage of mantled islets. Mantled islets are those surrounded by exocrine tissue and are difficult to purify by density gradient centrifugation, leading to poor islet recovery. Based on difference in extracellular matrix, and total collagen content between YDP and old donor pancreas (ODP, > 35 Y) led us to compare results from islet isolation using increased collagenase combination (ICC) or increased protease combination (IPC), to the standard enzyme combination (SEC) in a "trisected" pancreas model to overcome the donor-to-donor variability. These results showed a reduced percentage of mantled islets (17% ± 7.5%) and higher postpurification islet recovery (83.8% ± 5.6%) with IPC. Furthermore, these results were confirmed in 13 consecutive whole pancreas islet isolations utilizing IPC from VitaCyte, Roche, or SERVA collagenase-protease enzyme mixtures. Results obtained from in vitro and in vivo islet functional assessment indicated that islets isolated using IPC retained normal islet morphology, insulin secretion, and the ability to reverse diabetes after transplantation in diabetic nude mice. This is the first report utilizing trisected pancreas to assess the effectiveness of different enzyme combinations to improve islet recovery from young donor pancreases.


Asunto(s)
Colagenasas/metabolismo , Matriz Extracelular/metabolismo , Trasplante de Islotes Pancreáticos/métodos , Islotes Pancreáticos/citología , Péptido Hidrolasas/metabolismo , Donantes de Tejidos/provisión & distribución , Obtención de Tejidos y Órganos/normas , Adolescente , Adulto , Factores de Edad , Femenino , Estudios de Seguimiento , Humanos , Islotes Pancreáticos/metabolismo , Masculino , Preservación de Órganos/métodos , Adulto Joven
9.
Am J Transplant ; 18(2): 478-485, 2018 02.
Artículo en Inglés | MEDLINE | ID: mdl-29044985

RESUMEN

A high number of human islets can be isolated by using modern purified tissue dissociation enzymes; however, this requires the use of >20 Wunsch units (WU)/g of pancreas for digestion. Attempts to reduce this dose have resulted in pancreas underdigestion and poor islet recovery but improved islet function. In this study, we achieved a high number of functional islets using a low dose of recombinant collagenase enzyme mixture (RCEM-1200 WU rC2 and 10 million collagen-degrading activity [CDA] U of rC1 containing about 209 mg of collagenase to digest a 100-g pancreas). The collagenase dose used in these isolations is about 42% of the natural collagenase enzyme mixture (NCEM) dose commonly used to digest a 100-g pancreas. Low-dose RCEM was efficient in digesting entire pancreases to obtain higher yield (5535 ± 830 and 2582 ± 925 islet equivalent/g, P < .05) and less undigested tissue (16.7 ± 5% and 37.8 ± 3%, P < .05) compared with low-dose NCEM (12WU/g). Additionally, low-dose RCEM islets retained better morphology (confirmed with scanning electron microscopy) and higher in vitro basal insulin release (2391 ± 1342 and 1778 ± 978 µU/mL; P < .05) compared with standard-dose NCEM. Nude mouse bioassay demonstrated better islet function for low-dose RCEM (area under the curve [AUC] 24 968) compared with low-dose (AUC-38 225) or standard-dose NCEM (AUC-38 685), P < .05. This is the first report indicating that islet function can be improved by using low-dose rC1rC2 (RCEM).


Asunto(s)
Colagenasas/administración & dosificación , Diabetes Mellitus Experimental/terapia , Trasplante de Islotes Pancreáticos , Islotes Pancreáticos/fisiología , Metaloproteinasa 8 de la Matriz/administración & dosificación , Páncreas/metabolismo , Proteínas Recombinantes/administración & dosificación , Adulto , Animales , Células Cultivadas , Femenino , Humanos , Insulina/metabolismo , Islotes Pancreáticos/citología , Masculino , Ratones , Ratones Desnudos , Adulto Joven
11.
Electrophoresis ; 38(11): 1441-1449, 2017 06.
Artículo en Inglés | MEDLINE | ID: mdl-28112416

RESUMEN

Two dielectrophoresis systems are introduced where the induced dielectrophoretic force is constant throughout the experimental region, resulting in uniform (isomotive) microparticle translation. Isomotive dielectrophoresis (isoDEP) is accomplished through a unique geometry where the gradient of the field-squared (∇Erms2) is constant, a characteristic that is otherwise highly nonuniform in traditional DEP platforms. The governing isoDEP equations were derived herein and applied to two different isoDEP prototypes: (i) one fabricated from deep reactive ion etching (DRIE) of a conductive silicon wafer (1-10 Ω-cm) whose patterned features served as electrodes and microchannel sidewalls simultaneously; (ii) a second where the electric field is applied lengthwise through a PDMS microchannel whose geometry follows a specific curvature. Both positive and negative dielectrophoresis was demonstrated with the isoDEP devices using silver-coated hollow glass spheres and polystyrene particles, respectively. Particle tracking was used to compare particle trajectory with the expected dielectrophoretic response; further, particle velocity was used to measure the Clausius-Mossotti factor of individual polystyrene particles (18-24.9 µm) in both devices with a value of -0.40 ± 0.063 (n = 110) and -0.48 ± 0.055 (n = 18) for the DRIE and PDMS isoDEP platforms, respectively. The isoDEP platform is capable of analyzing multiple particles simultaneously, providing greater throughput than traditional electrorotation platforms.


Asunto(s)
Simulación por Computador , Electroforesis por Microchip , Diseño de Equipo , Electroósmosis , Electroforesis por Microchip/instrumentación , Electroforesis por Microchip/métodos , Diseño de Equipo/instrumentación , Diseño de Equipo/métodos , Microelectrodos , Modelos Teóricos , Tamaño de la Partícula , Poliestirenos
12.
Curr Opin Organ Transplant ; 22(5): 452-462, 2017 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-28759462

RESUMEN

PURPOSE OF REVIEW: The current article reviews the rationale, sources and preparation of pig islets for xenotransplantation, and presents current progress in solving the problems associated with establishing pig islet transplant as a clinical treatment for type 1 diabetes. SUMMARY: Islet transplantation is an effective treatment option for type 1 diabetes, but the available supply of human pancreases is insufficient to meet the need and demand for obtaining islets. Pig islets provide a readily available source for islet transplantation, with trials in non-human primates demonstrating their potential to reverse diabetes. The risk of zoonosis can be reduced by designated pathogen-free breeding of the donor pigs, but porcine endogenous retroviruses (PERVs) that are integrated into the genome of all pigs are especially difficult to eliminate. However, clinical trials have demonstrated an absence of PERV transmission with a significant reduction in the number of severe hypoglycemic episodes and up to 30% reduction in exogenous insulin doses. A number of methods such as production of various transgenic pigs to better xenotransplantation efficiency and the encapsulation of islets to isolate them from the host immune system are currently being tested to overcome the xenograft immune rejection. Furthermore, ongoing research is also shedding light on factors such as the age and breed of the donor pig to determine the optimal islet quantity and function.


Asunto(s)
Diabetes Mellitus Tipo 1/cirugía , Trasplante de Islotes Pancreáticos/métodos , Trasplante Heterólogo/métodos , Animales , Modelos Animales de Enfermedad , Humanos , Porcinos
13.
Curr Opin Organ Transplant ; 22(5): 490-498, 2017 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-28873074

RESUMEN

PURPOSE OF REVIEW: Controlling acute allograft rejection following vascularized composite allotransplantation requires strict adherence to courses of systemic immunosuppression. Discovering new methods to modulate the alloreactive immune response is essential for widespread application of vascularized composite allotransplantation. Here, we discuss how adipose-derived cellular therapies represent novel treatment options for immune modulation and tolerance induction in vascularized composite allotransplantation. RECENT FINDINGS: Adipose-derived mesenchymal stromal cells are cultured from autologous or allogeneic adipose tissue and possess immunomodulatory qualities capable of prolonging allograft survival in animal models of vascularized composite allotransplantation. Similar immunosuppressive and immunomodulatory effects have been observed with noncultured adipose stromal-vascular-fraction-derived therapies, albeit publication of in-vivo stromal vascular fraction cell modulation in transplantation models is lacking. However, both stromal vascular fraction and adipose derived mesenchymal stem cell therapies have the potential to effectively modulate acute allograft rejection via recruitment and induction of regulatory immune cells. SUMMARY: To date, most reports focus on adipose derived mesenchymal stem cells for immune modulation in transplantation despite their phenotypic plasticity and reliance upon culture expansion. Along with the capacity for immune modulation, the supplemental wound healing and vasculogenic properties of stromal vascular fraction, which are not shared by adipose derived mesenchymal stem cells, hint at the profound therapeutic impact stromal vascular fraction-derived treatments could have on controlling acute allograft rejection and tolerance induction in vascularized composite allotransplantation. Ongoing projects in the next few years will help design the best applications of these well tolerated and effective treatments that should reduce the risk/benefit ratio and allow more patients access to vascularized composite allotransplantation therapy.


Asunto(s)
Tejido Adiposo/trasplante , Supervivencia de Injerto/inmunología , Terapia de Inmunosupresión/métodos , Alotrasplante Compuesto Vascularizado/métodos , Animales , Humanos , Ratas , Ratas Endogámicas Lew , Porcinos
14.
Electrophoresis ; 37(4): 658-65, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26613811

RESUMEN

Rapid electrokinetic patterning (REP) is an emerging optoelectric technique that takes advantage of laser-induced AC electrothermal flow and particle-electrode interactions to trap and translate particles. The electrothermal flow in REP is driven by the temperature rise induced by the laser absorption in the thin electrode layer. In previous REP applications 350-700 nm indium tin oxide (ITO) layers have been used as electrodes. In this study, we show that ITO is an inefficient electrode choice as more than 92% of the irradiated laser on the ITO electrodes is transmitted without absorption. Using theoretical, computational, and experimental approaches, we demonstrate that for a given laser power the temperature rise is controlled by both the electrode material and its thickness. A 25-nm thick Ti electrode creates an electrothermal flow of the same speed as a 700-nm thick ITO electrode while requiring only 14% of the laser power used by ITO. These results represent an important step in the design of low-cost portable REP systems by lowering the material cost and power consumption of the system.


Asunto(s)
Técnicas Electroquímicas/métodos , Micromanipulación/métodos , Modelos Teóricos , Imagen Óptica/métodos , Electrodos
15.
Biotechnol Bioeng ; 113(6): 1336-44, 2016 06.
Artículo en Inglés | MEDLINE | ID: mdl-26615057

RESUMEN

Electrical impedance techniques have been used to characterize endothelium morphology, permeability, and motility in vitro. However, these impedance platforms have been limited to either static endothelium studies and/or induced laminar fluid flow at a constant, single shear stress value. In this work, we present a microfabricated impedance sensor for real-time, in vitro characterization of human umbilical vein endothelial cells (HUVECs) undergoing oscillatory hydrodynamic shear. Oscillatory shear was applied with an orbital shaker and the electrical impedance was measured by a microfabricated impedance chip with discrete electrodes positioned at radial locations of 0, 2.5, 5.0, 7.5, 10.0, and 12.5 mm from the center of the chip. Depending on their radial position within the circular orbital platform, HUVECs were exposed to shear values ranging between 0.6 and 6.71 dyne/cm(2) (according to numerical simulations) for 22 h. Impedance spectra were fit to an equivalent circuit model and the trans-endothelial resistance and monolayer's capacitance were extracted. Results demonstrated that, compared to measurements acquired before the onset of shear, cells at the center of the platform that experienced low steady shear stress (∼2.2 dyne/cm(2) ) had an average change in trans-endothelial resistance of 6.99 ± 4.06% and 1.78 ± 2.40% change in cell capacitance after 22 hours of shear exposure; cells near the periphery of the well (r = 12.5 mm) experienced transient shears (2.5-6.7 dyne/cm(2) ) and exhibited a greater change in trans-endothelial resistance (24.2 ± 10.8%) and cell capacitance (4.57 ± 5.39%). This study, demonstrates that the orbital shear platform provides a simple system that can capture and quantify the real-time cellular morphology as a result of induced shear stress. The orbital shear platform presented in this work, compared to traditional laminar platforms, subjects cells to more physiologically relevant oscillatory shear as well as exposes the sample to several shear values simultaneously. Biotechnol. Bioeng. 2016;113: 1336-1344. © 2015 Wiley Periodicals, Inc.


Asunto(s)
Células Endoteliales/fisiología , Sistemas Microelectromecánicos/instrumentación , Estimulación Física/instrumentación , Pletismografía de Impedancia/instrumentación , Reología/instrumentación , Resistencia al Corte/fisiología , Separación Celular/instrumentación , Células Cultivadas , Sistemas de Computación , Células Endoteliales/citología , Diseño de Equipo , Análisis de Falla de Equipo , Humanos , Hidrodinámica , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Vibración
16.
Transpl Int ; 29(6): 644-54, 2016 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-26924305

RESUMEN

Transplantation of vascularized composite tissue is a relatively new field that is an amalgamation of experience in solid organ transplantation and reconstructive plastic and orthopedic surgery. What is novel about the immunobiology of VCA is the addition of tissues with unique immunologic characteristics such as skin and vascularized bone, and the nature of VCA grafts, with direct exposure to the environment, and external forces of trauma. VCAs are distinguished from solid organ transplants by the requirement of rigorous physical therapy for optimal outcomes and the fact that these procedures are not lifesaving in most cases. In this review, we will discuss the immunobiology of these systems and how the interplay can result in pathology unique to VCA as well as provide potential targets for therapy.


Asunto(s)
Sistema Inmunológico , Alotrasplante Compuesto Vascularizado/métodos , Animales , Huesos/inmunología , Rechazo de Injerto/inmunología , Trasplante de Mano/métodos , Humanos , Tolerancia Inmunológica , Piel/inmunología , Trasplante de Piel/métodos , Cirugía Plástica/métodos , Trasplante Homólogo
17.
Electrophoresis ; 36(15): 1674-80, 2015 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-26013358

RESUMEN

Rapid electrokinetic patterning (REP) is a technique for creating self-assembled monolayers (SAMs) of spherical particles in a liquid medium, and dynamically controlling them though the simultaneous application of an electric field and optically induced temperature gradients. Previous work has investigated and characterized REP axisymmetric aggregations generated from a focus laser within a uniform electric field; work herein characterizes line-shaped particle assemblies derived from the application of a linearly scanned laser. The resulting aggregations of spherical polystyrene particles (1 µm) suspended in low-conductivity aqueous potassium chloride solution (KCl, 2.5 mS/m) resembled elliptical-shaped crystalline geometries. The mean particle-to-particle spacing within the aggregation remained greater than 1.5 diameters for experiments herein (6.5 Vrms , 30 kHz) due to dipole-dipole repulsive forces. Interparticle spacing demonstrated a linear relationship (1.6-2.1 µm) with increasing scanning lengths (up to 83 µm), decreased from 1.9 to 1.7 µm with increasing scanning frequency (0.38-16 Hz) for a 53 µm scan length, and decreased from 2.0 to 1.6 µm with increasing laser power (11.9-18.8 mW) for a 59 µm, 16 Hz laser scan.


Asunto(s)
Coloides/química , Microfluídica/métodos , Procesamiento de Imagen Asistido por Computador , Microesferas , Poliestirenos/química
18.
Electrophoresis ; 36(15): 1681-9, 2015 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-26010255

RESUMEN

Interdigitated electrodes are used in electrokinetic lab-on-a-chip devices for dielectrophoretic trapping and characterization of suspended particles, as well as the production of field-induced fluid flow via AC electroosomosis and electrothermal mechanisms. However, the optimum design for dielectrophoresis, that if symmetrical electrodes, cannot induce bulk electrohydrodynamic pumping. In addition, the mechanism of intrinsic electrothermal pumping is affected by the properties of the fluid, with thermal fields being generated by Joule Heating. This work demonstrates the incorporation of an underlying thin film heater, electrically isolated from the interdigitated electrodes by an insulator layer, to enhance bulk electrothermal pumping. The use of integrated heaters allows the thermal field generation to be controlled independently of the electric field. Numerical simulations are performed to demonstrate the importance of geometrical arrangement of the heater with respect to the interdigitated electrodes, as well as electrode size, spacing, and arrangement. The optimization of such a system is a careful balance between electrokinetics, heat transfer, and fluid dynamics. The heater location and electrode spacing influence the rate of electrothermal pumping significantly more than electrode width and insulator layer thickness. This demonstration will aid in the development of microfluidic electrokinetic systems that want to utilize the advantages associated with electrothermal pumping while simultaneously applying other lab-on-a-chip electrokinetics like dielectrophoresis.


Asunto(s)
Electroforesis/instrumentación , Técnicas Analíticas Microfluídicas/instrumentación , Modelos Teóricos , Electrodos , Diseño de Equipo , Termodinámica
19.
Soft Matter ; 11(21): 4266-72, 2015 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-25899138

RESUMEN

We report the results of a study characterizing the behavior of colloid aggregations under manipulation of a technique known as Rapid Electrokinetic Patterning (REP) - this technique is capable of dynamically manipulating the crystallinity of 2D colloid aggregations, potentially enabling dynamically tunable photonic crystals. Herein, aggregations of spherical polystyrene particles 1.0 µm in diameter suspended in a low conductivity aqueous solution were collected at the surface of an indium-tin oxide coated glass slide. The uniform AC field coupled with laser-induced heating produced electrothermal hydrodynamics which is responsible for the self-assembly characteristics of the planar colloidal aggregation. REP was characterized experimentally by analyzing the mutual particle spacing within the aggregation as a function of the AC signal and laser power. Numerical simulations justified the assumption that the primary forces responsible for colloidal patterning herein are Stokes drag forces and dipole-dipole repulsive forces.

20.
Ther Innov Regul Sci ; 58(6): 1042-1052, 2024 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-39060838

RESUMEN

OBJECTIVES: This manuscript presents a comprehensive framework for the assessment of the value of real-world evidence (RWE) in healthcare decision-making. While RWE has been proposed to overcome some limitations of traditional, one-off studies, no systematic framework exists to measure if RWE actually lowers the burden. This framework aims to fill that gap by providing conceptual approaches for evaluating the time and cost efficiencies of RWE, thus guiding strategic investments in RWE infrastructure. METHODS: The framework consists of four components: (114th Congress. 21st Century Cures Act.; 2015. https://www.congress.gov/114/plaws/publ255/PLAW-114publ255.pdf .) identification of stakeholders using and producing RWE, (National Health Council. Glossary of Patient Engagement Terms. Published 2019. Accessed May 18. 2021. https://nationalhealthcouncil.org/glossary-of-patient-engagement-terms/ .) understanding value propositions on how RWE can benefit stakeholders, (Center for Drug Evaluation and Research. CDER Patient-Focused Drug Development. U.S. Food & Drug Administration.) defining key performance indicators (KPIs), and (U.S. Department of Health and Human Services - Food and Drug Administration: Center for Devices and Radiological Health and Center for Biologics Evaluation and Research. Use of Real-World Evidence to Support Regulatory Decision-Making for Medical Devices - Guidance for Industry and Food and Drug Administration Staff. 2017. http://www.fda.gov/BiologicsBloodVaccines/GuidanceComplianceRegulatoryInformation/Guida .) establishing metrics and case studies to assess value. KPIs are categorized as 'better, faster, or cheaper" as an indicator of value: better focusing on high-quality actionable evidence; 'faster,' denoting time-saving in evidence generation, and 'cheaper,' emphasizing cost-efficiency decision compared to methodologies that do not involve data routinely collected in clinical practice. Metrics and relevant case studies are tailored based on stakeholder value propositions and selected KPIs that can be used to assess what value has been created by using RWE compared to traditional evidence-generation approaches and comparing different RWE sources. RESULTS: Operationalized through metrics and case studies drawn from the literature, the value of RWE is documented as improving treatment effect heterogeneity evaluation, expanding medical product labels, and expediting post-market compliance. RWE is also shown to reduce the cost and time required to produce evidence compared to traditional one-off approaches. An original example of a metric that measures the time saved by RWE methods to detect a signal of a product failure was presented based on analysis of the National Cardiovascular Disease Registry. CONCLUSIONS: The framework presented in this manuscript offers a comprehensive approach for evaluating the value of RWE, applicable to all stakeholders engaged in leveraging RWE for healthcare decision-making. Through the proposed metrics and illustrated case studies, valuable insights are provided into the heightened efficiency, cost-effectiveness, and improved decision-making within clinical and regulatory domains facilitated by RWE. While this framework is primarily focused on medical devices, it could potentially inform the determination of RWE value in other medical products. By discerning the variations in cost, time, and data utility among various evidence-generation methods, stakeholders are empowered to invest strategically in RWE infrastructure and shape future research endeavors.


Asunto(s)
Sistema de Registros , Participación de los Interesados , Humanos , Análisis Costo-Beneficio , Toma de Decisiones , Estados Unidos
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