Este estudio fue financiado por Boston neuromodulación Científico.

1. Introducción: Estimulación de la médula espinal, o SCS, se ha aplicado clínicamente desde 1967, cuando el Dr. Norman Shealy primera implantados electrodos de estimulación en la columna dorsal en un intento de proporcionar un alivio para los pacientes con dolor crónico, intratable (Shealy et al., 1967). SCS es la aplicación clínica de la teoría de la puerta, que postula que la activación de los nervios aferentes mielinizadas grandes que median en el tacto y las sensaciones de presión, pueden inhibir o &quot;cerrar la puerta&quot; en la transmisión de las señales de dolor a los centros superiores del cerebro (Melzack y Wall , 1965). Tecnología para el SCS ha mejorado en las últimas décadas, con equipos de estimulación más fiable mejor diseñados para estimular las columnas dorsales ha evolucionado. La clave para estas mejoras ha sido un mayor conocimiento de la neuroanatomía y la neurofisiología de la médula espinal correspondiente a la estimulación eléctrica clínica. Este entendimiento ha sido propuesta por el modelado computacional del SCS. Modelado computacional de las neuronas se ha utilizado para entender los mecanismos básicos para la estimulación neural desde el modelo matemático de Hodgkin y Huxley fue descrita por primera vez (Hodgkin y Huxley, 1952). La actividad neuronal es modulada por los campos eléctricos aplicados como la inyección intracelular y extracelular actuales campos potenciales. Ranck cualitativamente discute cómo los cambios en el voltaje extracelular en las proximidades de un axón causar algunas regiones de la membrana del axón para despolarizar y otros hiperpolarizan a (Ranck, 1975). Un modelo computacional para SCS fue desarrollado inicialmente por Coburn y el pecado (Coburn, 1980) y fue significativamente promovido por Holsheimer y sus colegas, a partir de Struijk y desarrollo Holsheimer de un modelo de campo en tres dimensiones del SCS (Holsheimer y Struijk, 1988). Su modelo de cálculo estima el efecto de los parámetros anatómicos en los umbrales de las fibras de la columna dorsal (Struijk et al., 1992), predijo la posible ubicación de la excitación de las fibras de la raíz dorsal (Struijk et al., 1993b), y analizó el efecto de la CSF de espesor (Struijk et al, 1993a.) con validaciones clínicas (He et al, 1994;. Holsheimer et al, 1995a;.. Holsheimer et al, 1994). El modelo contribuyó significativamente al diseño de diseño de la estimulación de plomo, lo que sugiere los parámetros óptimos para el tamaño y el espaciamiento de contacto (Holsheimer y Struijk, 1992; Holsheimer y Wesselink, 1997), para favorecer la estimulación preferencial de las fibras de la columna dorsal sobre fibras de la raíz (Holsheimer et al,. 1995b). 2. Material y métodos: Definición de modelos matemáticos Un matemático de elementos finitos (FEM) fue creado el modelo de la médula espinal dorsal baja y su entorno. El modelo de elementos finitos consistió en la materia de la médula espinal blanco y gris, líquido cefalorraquídeo, la duración, el tejido espacio epidural, el hueso vertebral y dos conductores cilíndricos multicontacto. Cada derivación consistió en ocho cilíndrica de platino iridio contactos (dominios de la realización, la longitud de 3 mm y 1,25 mm de diámetro), separados por la longitud de 1 mm de aislante de polímero (no la realización de los dominios, la longitud de 1 mm). Los cables fueron colocados en el dorso, encima de la duramadre, y simétrica, de 1 mm a cada lado de la línea media de la médula espinal. En el modelo, el &quot;grueso&quot; de la capa de líquido cefalorraquídeo entre los contactos y la superficie dorsal de la médula espinal (DCSF) se especificó que 3,2 mm. La geometría del modelo se ilustra en la Figura 1 A y resistividad eléctrica se presentan en la Tabla I, los valores procedentes sobre todo de la literatura (Holsheimer, 2002;. Wesselink et al, 1999). El volumen fue de malla con más de 1 millón de nodos, con una malla de alta densidad en la región cerca de donde se encuentran los electrodos como se ilustra en la Figura 1B. <img src="/files/ftp_upload/2443/2443fig1.jpg" alt="Figura 1" /> Figura 1. Representación de la malla de la FEM de la médula espinal y el plomo multicontacto. (A) los componentes y la estructura del modelo. (B) de malla del modelo - sólo la parte de alta densidad se muestra. La malla fue segmentada en las secciones de la densidad de nodos variable: cerca de los contactos (≤ 300 micras), aislante, la duración y la médula espinal (≤ 750 micras), el espacio epidural (≤ 3000 m), y el hueso vertebral (≤ 5000 m). <img src="/files/ftp_upload/2443/2443table1.jpg" alt="Tabla 1" /> Tabla 1 los valores de resistividad de los dominios de FEM (Holsheimer, 2002;. Wesselink et al, 1999). Y la modificación (espacio epidural) para que coincida con los datos clínicos. La geometría de la médula espinal (Figura 2) fue creado con una combinación de características de las fuentes de la literatura relevante. La sección transversal de la médula se deriva de Kameyama y otros, y la raíz dorsal (RD) la trayectoria de Struijk et al se adoptó (Kameyama et al, 1996;... Struijket al., 1993b). La columna dorsal (DC), las fibras se colocaron en la red regular de (200um de dirección medio-lateral y la dirección dorsoventral 100um; vea la Figura 2A) y proyectada en la dirección rostrocaudal. Cada DR fue modelada como la fibra de &quot;madre&quot; de mayor diámetro conectadas a las fibras de la hija de &quot;bifurcación de menor diámetro (Fig. 2B). <img src="/files/ftp_upload/2443/2443fig2.jpg" alt="Figura 2" /> Figura 2. Estructura del modelo de la médula espinal. (A) vista transaccional de la médula espinal y la ubicación de las fibras de la columna dorsal. (B) las raíces dorsales se componen de una fibra de la madre y la hija de fibras bifurcadas. La trayectoria de la fibra de la madre fue digitalizada a partir de Struijk 1993. (C) Tres vista tridimensional de la médula espinal y las fibras DR. Modelo de Investigación Una vez que los cables fueron colocados dentro del modelo, los dos tipos de estimuladores se llevaron a cabo mediante la definición de las corrientes de dos contactos paralelos. Para un sistema de fuente única, hay tres métodos posibles para suministrar corriente: a. el contacto más a la izquierda tiene toda la corriente; b. los dos contactos cada entregar el 50% de la corriente; c. el contacto de la derecha ofrece toda la corriente. Observamos aquí que la impedancia de los dos contactos se supone igual, aunque es poco probable que sea cierto en la aplicación clínica. Para el sistema de fuentes múltiples, cada contacto se definió a tener su propia fuente controlable actual incremento del 1% los cambios actuales entre los contactos. En otras palabras, si la corriente total entregada a los dos contactos es de 10 mA, en el sistema de fuentes múltiples de la corriente a cada contacto se ha especificado a cualquier parte del total, siempre y cuando la suma de las corrientes de 10 mA a través de cada contacto con la igualdad. Por ejemplo, el contacto de la izquierda podría suponer un 6,8 mA en el contacto más a la derecha entonces entregar 3,2 mA. Para el sistema de fuentes múltiples, 100 fracciones se divide de la corriente se programaron de esta forma. Para el cálculo de la región de activación dentro de las columnas dorsales de cada sistema, un análisis de la función se llevó a cabo la activación. La función de activación es una aproximación del cambio en el potencial de membrana cuando la corriente de estimulación extracelular se aplica al tejido nervioso de un electrodo y la geometría de la fibra. La región de activación se define como el lugar geométrico de las fibras en el modelo en el que la función de activación (o la diferencia simplemente segundos de tensiones a lo largo del axón) supera un determinado umbral (por ejemplo, 0.1mV/mm2). El punto central de la estimulación se definió y se calcula como el centroide geométrico de la región 3-dimensional de la activación. Para determinar la amplitud de la estimulación, los dos contactos se especifica que los cátodos (50% y 50% negativo en dos contactos) en una configuración monopolar (con fuente de corriente suministrado con la densidad de corriente equivalente de las fronteras del modelo). La amplitud de estimulación entonces iterativamente hasta que el aumento de la fibra activa por primera vez se observó (esto siempre fue una fibra de la columna dorsal). Esta primera activación se supone que se correlacionan con la primera percepción de parestesia por un paciente en el ámbito clínico. En el modelo, la corriente se aumentó a 1,4 * (mA para activar primera fibra) y el centroide de la región como resultado de la activación se calculó. Centroides de todas las medidas de gobierno (100:0 a 0:100) se calcularon con una amplitud determinada en el paso anterior. Resolución de cambio promedio fue centroide gama, la ubicación del centroide dividido por pasos actuales. 3. Resultado: Cuando la estimulación de dirección mediolaterally entre los conductores de dos, el modelo computacional predice que un dispositivo con fuentes independientes de corriente para cada contacto pueden dirigirse a los puntos más centrales de la estimulación en la columna dorsal de un sistema de fuente única (100 vs 3). Como resultado de esto, la resolución de ajuste del punto central de la estimulación es de 30 um con un sistema de múltiples fuentes, un aproximado de 50 veces mayor en comparación con los sistemas de una sola fuente (ver Figura 3). <img src="/files/ftp_upload/2443/2443fig3.jpg" alt="Figura 3" /> Figura 3. El modelo computacional hace las siguientes predicciones. Configuración de doble A. conducir: 2,0 mm de separación entre los conductores con la estimulación monopolar. B. dispositivos de un solo origen que son una fuente única de poder compartido para todos los contactos pueden dirigirse a tres puntos centrales de la estimulación cuando se cambia la estimulación mediolaterally (un tamaño de paso de 1 mm en promedio de 2 mm de separación de plomo). C: Un dispositivo con una fuente de energía específica para cada contacto pueden dirigirse a 100 puntos centrales lateral de la columna dorsal cuando fraccionando actual en incrementos del 1%, o 10 puntos centrales cuando fraccionando en incrementos de 10% (un tamaño de paso de 0,02 mm para el 1% pasos y 0,2 mm de los pasos del 10% en promedio).

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Los autores son empleados de Boston neuromodulación Científico.

La capacidad de las regiones del centro de estimulación en la columna dorsal de alta resolución puede permitir una mejor optimización de la superposición de la parestesia, dolor en los pacientes. Es decir, en un paciente determinado, la región de activación en la columna dorsal puede ser enfocado a maximizar la cobertura de las zonas dolorosas y minimizar los efectos secundarios (debido a la estimulación de las fibras no deseadas, que pueden generar parestesia en lugares no deseados o crear motor o autonómica efectos).

<ul><li> NEURON ( <a href="http://www.neuron.yale.edu">http://www.neuron.yale.edu</a> ) </li><li> ANSYS (Canonsburg, <a href="http://www.ansys.com">http://www.ansys.com</a> ) </li><li> Matlab (Natick, MA, <a href="http://www.mathworks.com">http://www.mathworks.com</a> ) </li></ul>

dorsal column steerability with dual parallel leads using dedicated power sources:  a computational model

En la estimulación de la médula espinal (SCS), la concordancia de la estimulación inducida por parestesias en las regiones del cuerpo doloroso es una condición necesaria para la eficacia terapéutica. Dado que los patrones de pacientes el dolor puede ser único, una configuración de estimulación frecuente es la colocación de dos cables en paralelo en el espacio epidural dorsal. Esta construcción proporciona flexibilidad en la dirección de la corriente de estimulación mediolaterally sobre la columna dorsal para lograr una mejor parestesias dolor se superponen. Utilizando un modelo matemático con una distribución de las fibras de diámetro exacto, se estudió la capacidad de los paralelos de doble lleva a orientar la estimulación entre contactos adyacentes en paralelo dual lleva usando (1) un sistema de fuente única, y (2) un sistema de múltiples fuentes, con un dedicada fuente de corriente para cada contacto. El modelo de volumen de un conductor de la médula espinal torácica baja con epidural posicionado en paralelo de dos (2 mm de separación) lleva percutánea fue creado primero, y el campo eléctrico se ha calculado utilizando ANSYS, uno de los elementos finitos herramienta de modelado. La función de la activación de las fibras 10 um se calcula como la segunda diferencia del potencial extracelular a lo largo de los nodos de Ranvier en las fibras nerviosas de la columna dorsal. El volumen de activación (VOA) y el punto central de la VOA se calcularon utilizando un umbral predeterminado de la función de activación. El modelo se compararon los resultados con el campo de dirección única fuente frente a los sistemas dedicados de la fuente de alimentación de doble conduce la estimulación de 8 contactos. El modelo predijo que el sistema de origen multi-objetivo puede obtener más puntos centrales de la estimulación en la columna dorsal de un sistema de fuente única (100 frente a 3) y el paso de la dirección media de dirección mediolateral es de 0,02 mm para sistemas multi-fuente frente a 1 mm para los sistemas de fuente única, una mejora de 50 veces. La capacidad de las regiones del centro de estimulación en la columna dorsal de alta resolución puede permitir una mejor optimización de la superposición de la parestesia, dolor en los pacientes.

Watch this Scientific Journal Video about Dorsal Column Steerability with Dual Parallel Leads using Dedicated Power Sources:  A Computational Model at JoVE.com

Dorsal Column Steerability with Dual Parallel Leads using Dedicated Power Sources:  A Computational Model

Utilizando un modelo matemático de la estimulación de la médula espinal, se encontró que un sistema de múltiples fuentes con fuentes de energía independientes para cada contacto puede dirigir más los puntos centrales de la estimulación en la columna dorsal (100 vs 3) y tiene 50 veces más resolución de la dirección de campo ( 0,02 mm frente a 1 mm) que un sistema de fuente única.

Manejabilidad en la columna dorsal con cables paralelos de doble uso dedicado de fuentes de energía: un modelo computacional

In spinal cord stimulation (SCS), concordance of stimulation-induced paresthesia over painful body regions is a necessary condition for therapeutic ...

dorsal-column-steerability-with-dual-parallel-leads-using-dedicated

Universidad de Cartagena UDEC

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JoVE Journal

Medicine

11.8K vistas.  Neuromodulation. Utilizando un modelo matemático de la estimulación de la médula espinal, se encontró que un sistema de múltiples fuentes con fuentes de energía independientes para cada contacto puede dirigir más los puntos centrales de la estimulación en la columna dorsal (100 vs 3) y tiene 50 veces más resolución de la dirección de campo ( 0,02 mm frente a 1 mm) que un sistema de fuente única.

Video: Dorsal Column Steerability with Dual Parallel Leads using Dedicated Power Sources:  A Computational Model

A Novel Capsulorhexis Technique Using Shearing Forces with Cystotome

Purpose:
To demonstrate a capsulorhexis technique using predominantly shearing forces with a cystotome on a virtual reality simulator and on a human eye.
Method:
Our technique involves creating the initial anterior capsular tear with a cystotome to raise a flap. The flap left unfolded on the lens surface. The cystotome tip is tilted horizontally and is engaged on the flap near the leading edge of the tear. The cystotome is moved in a circular fashion to direct the vector forces. The loose flap is constantly swept towards the centre so that it does not obscure the view on the tearing edge.
Results:
Our technique has the advantage of reducing corneal wound distortion and subsequent anterior chamber collapse. The capsulorhexis flap is moved away from the tear leading edge allowing better visualisation of the direction of tear. This technique offers superior control of the capsulorhexis by allowing the surgeon to change the direction of the tear to achieve the desired capsulorhexis size.
Conclusions:
The EYESI Surgical Simulator is a realistic training platform for surgeons to practice complex capsulorhexis techniques. The shearing forces technique is a suitable alternative and in some cases a far better technique in achieving the desired capsulorhexis.

This video demonstrates a novel capsulorhexis technique in modern cataract surgery. Capsulorhexis is the most difficult and important part of phacoemulsification surgery.

Una técnica de capsulorrexis novela usando las fuerzas de cizallamiento con cistítomo

Purpose:
To demonstrate a capsulorhexis technique using predominantly shearing forces with a cystotome on a virtual reality simulator and on a human eye....

Investigación

Medicina

In vivo Dual Substrate Bioluminescent Imaging

Our understanding of how and when breast cancer cells transit from established primary tumors to metastatic sites has increased at an exceptional rate since the advent of in vivo bioluminescent imaging technologies 1-3. Indeed, the ability to locate and quantify tumor growth longitudinally in a single cohort of animals to completion of the study as opposed to sacrificing individual groups of animals at specific assay times has revolutionized how researchers investigate breast cancer metastasis. Unfortunately, current methodologies preclude the real-time assessment of critical changes that transpire in cell signaling systems as breast cancer cells (i) evolve within primary tumors, (ii) disseminate throughout the body, and (iii) reinitiate proliferative programs at sites of a metastatic lesion. However, recent advancements in bioluminescent imaging now make it possible to simultaneously quantify specific spatiotemporal changes in gene expression as a function of tumor development and metastatic progression via the use of dual substrate luminescence reactions. To do so, researchers take advantage for two light-producing luciferase enzymes isolated from the firefly (Photinus pyralis) and sea pansy (Renilla reniformis), both of which react to mutually exclusive substrates that previously facilitated their wide-spread use in in vitro cell-based reporter gene assays 4. Here we demonstrate the in vivo utility of these two enzymes such that one luminescence reaction specifically marks the size and location of a developing tumor, while the second luminescent reaction serves as a means to visualize the activation status of specific signaling systems during distinct stages of tumor and metastasis development. Thus, the objectives of this study are two-fold. First, we will describe the steps necessary to construct dual bioluminescent reporter cell lines, as well as those needed to facilitate their use in visualizing the spatiotemporal regulation of gene expression during specific steps of the metastatic cascade. Using the 4T1 model of breast cancer metastasis, we show that the in vivo activity of a synthetic Smad Binding Element (SBE) promoter was decreased dramatically in pulmonary metastasis as compared to that measured in the primary tumor 4-6. Recently, breast cancer metastasis was shown to be regulated by changes within the primary tumor microenvironment and reactive stroma, including those occurring in fibroblasts and infiltrating immune cells 7-9. Thus, our second objective will be to demonstrate the utility of dual bioluminescent techniques in monitoring the growth and localization of two unique cell populations harbored within a single animal during breast cancer growth and metastasis.

In vivo Dual Substrate Bioluminescent Imaging

Herein we describe the methods to construct, visualize, and quantify the bioluminescent reactions of both firefly and renilla luciferase enzymes expressed in metastatic breast cancer cells during their growth and metastasis in vivo.

En vivo doble sustrato bioluminiscentes imagen

Our understanding of how and when breast cancer cells transit from established primary tumors to metastatic sites has increased at an exceptional rate ...

Deep Neuromuscular Blockade Leads to a Larger Intraabdominal Volume During Laparoscopy

Shoulder pain is a commonly reported symptom following laparoscopic procedures such as myomectomy or hysterectomy, and recent studies have shown that lowering the insufflation pressure during surgery may reduce the risk of post-operative pain. In this pilot study, a method is presented for measuring the intra-abdominal space available to the surgeon during laproscopy, in order to examine whether the relaxation produced by deep neuromuscular blockade can increase the working surgical space sufficiently to permit a reduction in the CO2 insufflation pressure. Using the laproscopic grasper, the distance from the promontory to the skin is measured at two different insufflation pressures: 8 mm Hg and 12 mm Hg. After the initial measurements, a neuromuscular blocking agent (rocuronium) is administered to the patient and the intra-abdominal volume is measured again. Pilot data collected from 15 patients shows that the intra-abdominal space at 8 mm Hg with blockade is comparable to the intra-abdominal space measured at 12 mm Hg without blockade. The impact of neuromuscular blockade was not correlated with patient height, weight, BMI, and age. Thus, using neuromuscular blockade to maintain a steady volume while reducing insufflation pressure may produce improved patient outcomes.

This article presents a method for measuring the working abdominal volume during laproscopic myomectomy using the surgical grasper, and applies this technique to obtain pilot data on whether deep neuromuscular blockade (NMB) can enable the use of lower insufflation pressure. Reduced insufflation pressure during laproscopic surgery has been shown to reduce post-operative pain, and thus the use of NMB during surgery may enable improved patient outcomes.

El bloqueo neuromuscular profundo lleva a un volumen intraabdominal más grande durante la laparoscopia

Shoulder pain is a commonly reported symptom following laparoscopic procedures such as myomectomy or hysterectomy, and recent studies have shown that ...

Ischemic Tissue Injury in the Dorsal Skinfold Chamber of the Mouse: A Skin Flap Model to Investigate Acute Persistent Ischemia

Despite profound expertise and advanced surgical techniques, ischemia-induced complications ranging from wound breakdown to extensive tissue necrosis are still occurring, particularly in reconstructive flap surgery. Multiple experimental flap models have been developed to analyze underlying causes and mechanisms and to investigate treatment strategies to prevent ischemic complications. The limiting factor of most models is the lacking possibility to directly and repetitively visualize microvascular architecture and hemodynamics. The goal of the protocol was to present a well-established mouse model affiliating these before mentioned lacking elements. Harder et al. have developed a model of a musculocutaneous flap with a random perfusion pattern that undergoes acute persistent ischemia and results in ~50% necrosis after 10 days if kept untreated. With the aid of intravital epi-fluorescence microscopy, this chamber model allows repetitive visualization of morphology and hemodynamics in different regions of interest over time. Associated processes such as apoptosis, inflammation, microvascular leakage and angiogenesis can be investigated and correlated to immunohistochemical and molecular protein assays. To date, the model has proven feasibility and reproducibility in several published experimental studies investigating the effect of pre-, peri- and postconditioning of ischemically challenged tissue.

The window of the murine dorsal skinfold chamber presented visualizes a zone of acute persistent ischemia of a musculocutaneous flap. Intravital epi-fluorescence microscopy permits for direct and repetitive assessment of the microvasculature and quantification of hemodynamics. Morphologic and hemodynamic results can further be correlated with histological and molecular analyses.

Lesiones tejido isquémico en la Cámara de los pliegues cutáneos dorsal del ratón: Un modelo de la piel de la aleta para Investigar la isquemia aguda persistente

Despite profound expertise and advanced surgical techniques, ischemia-induced complications ranging from wound breakdown to extensive tissue necrosis are ...

Using Saccadometry with Deep Brain Stimulation to Study Normal and Pathological Brain Function

The oculomotor system involves a large number of brain areas including parts of the basal ganglia, and various neurodegenerative diseases including Parkinson's and Huntington's can disrupt it. People with Parkinson's disease, for example, tend to have increased saccadic latencies. Consequently, the quantitative measurement of saccadic eye movements has received considerable attention as a potential biomarker for neurodegenerative conditions. A lot more can be learned about the brain in both health and disease by observing what happens to eye movements when the function of specific brain areas is perturbed. Deep brain stimulation is a surgical intervention used for the management of a range of neurological conditions including Parkinson's disease, in which stimulating electrodes are placed in specific brain areas including several sites in the basal ganglia. Eye movement measurements can then be made with the stimulator systems both off and on and the results compared. With suitable experimental design, this approach can be used to study the pathophysiology of the disease being treated, the mechanism by which DBS exerts it beneficial effects, and even aspects of normal neurophysiology.

This paper describes the use of quantitative measurement of eye movements in conjunction with stimulation of focal areas of the deep brain in order to study physiology, pathophysiology, and the mechanisms of deep brain stimulation.

Usando Saccadometry con estimulación cerebral profunda para estudiar la función cerebral normal y patológica

The oculomotor system involves a large number of brain areas including parts of the basal ganglia, and various neurodegenerative diseases including ...

Isometric Contractility Measurement of the Mouse Mesenteric Artery Using Wire Myography

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and drugs. It is widely used in many studies on the physiological functions of vascular smooth muscle, the pathogenesis of vascular diseases such as hypertension, and the development of smooth muscle relaxant drugs. The mouse is a widely used model animal with a large pool of disease models and genetically modified strains. We introduced this method to measure the isometric contraction of mouse mesenteric artery in detail. A 1.4-mm segment of mouse mesenteric resistance artery was isolated and mounted on a myograph chamber by passing two steel wires through its lumen. After equilibration and normalization steps, the vessel segment was potentiated by a high-K+ solution twice prior to the contraction assay. As an example of the application of this method in drug development, we measured the relaxant effect of a novel natural substance, neoliensinine, isolated from a Chinese herb, embryos of the lotus seed (Nelumbo nucifera Gaertn.) on mouse mesenteric arteries. The vessel segments mounted on the myograph chamber were stimulated with a high-K+ solution. When the force tension reached a stable sustained phase, cumulative doses of neoliensinine were added to the chamber. We found that neoliensinine had a dose-dependent relaxant effect on smooth muscle contraction, thus suggesting that it bears potential activity against hypertension. In addition, as the vessel segment can survive at least 4 hours after mounting and maintain contractility induced by the high-K+ solution for many times, we suggest that the wire myograph system may be used for the time-consuming process of drug screening.

The wire myograph technique is used to investigate vascular smooth muscle functions and screen new drugs. We report a detailed protocol for measuring the isometric contractility of the mouse mesenteric artery and for screening new relaxants of vascular smooth muscle.

Medición de la contractilidad isométrica de la arteria mesentérica de ratón con cable miografía

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and ...

Murine Model of Central Venous Stenosis using Aortocaval Fistula with an Outflow Stenosis

Central venous stenosis is an important entity contributing to arteriovenous fistula (AVF) failure. A murine AVF model was modified to create a partial ligation of the inferior vena cava (IVC) in the outflow of the fistula, mimicking central venous stenosis. Technical aspects of this model are introduced. The aorta and IVC are exposed, following an abdominal incision. The infra-renal aorta and IVC are dissected for proximal clamping, and the distal aorta is exposed for puncture. The IVC at the midpoint between the left renal vein and the aortic bifurcation is carefully dissected to place an 8-0 suture beneath the IVC. After clamping the aorta and IVC, an AVF is created by puncturing the infra-renal aorta through both walls into the IVC with a 25 G needle, followed by ligating a 22 G intra-venous (IV) catheter and IVC together. The catheter is then removed, creating a reproducible venous stenosis without occlusion. The aorta and IVC are unclamped after confirming primary hemostasis. This novel model of central vein stenosis is easy to perform, reproducible, and will facilitate studies on AVF failure.

An aortocaval fistula was created by puncturing the murine infra-renal aorta through both walls into the inferior vena cava and was followed by creation of a stenosis in its outflow via partial ligation of the inferior vena cava. This reproducible model can be used to study central venous stenosis.

Modelo murino de estenosis venosa central usando fístula aortocaval con una estenosis de salida

Central venous stenosis is an important entity contributing to arteriovenous fistula (AVF) failure. A murine AVF model was modified to create a partial ...

A Porcine Corneal Endothelial Organ Culture Model Using Split Corneal Buttons

Experimental research on corneal endothelial cells is associated with several difficulties. Human donor corneas are scarce and rarely available for experimental investigations as they are normally needed for transplantation. Endothelial cell cultures often do not translate well to in vivo situations. Due to the biostructural characteristics of non-human corneas, stromal swelling during cultivation induces substantial corneal endothelial cell loss, which makes it difficult to perform cultivation for an extended period of time. Deswelling agents such as dextran are used to counteract this response. However, they also cause significant endothelial cell loss. Therefore, an ex vivo organ culture model not requiring deswelling agents was established. Pig eyes from a local slaughterhouse were used to prepare split corneal buttons. After partial corneal trephination, the outer layers of the cornea (epithelium, bowman layer, parts of the stroma) were removed. This significantly reduces corneal endothelial cell loss induced by massive stromal swelling and Descemet&#39;s membrane folding throughout longer cultivation periods and improves general preservation of the endothelial cell layer. Subsequent complete corneal trephination was followed by the removal of the split corneal button from the remaining eye bulb and cultivation. Endothelial cell density was assessed at follow-up times of up to 15 days after preparation (i.e., days 1, 8, 15) using light microscopy. The preparation technique used allows a better preservation of the endothelial cell layer enabled by less stromal tissue swelling, which results in slow and linear decline rates in split corneal buttons comparable to human donor corneas. As this standardized organo-typically cultivated research model for the first time allows a stable cultivation for at least two weeks, it is a valuable alternative to human donor corneas for future investigations of various external factors with regards to their effects on the corneal endothelium.

Here, a step-by-step protocol for the preparation and cultivation of porcine split corneal buttons is presented. As this organo-typically cultivated organ culture model shows cell death rates within 15 days, comparable to human donor corneas, it represents the first model allowing long-term cultivation of non-human corneas without adding toxic dextran.

Un modelo de cultivo de órgano endotelial Corneal porcino usando botones de córnea divididos

Experimental research on corneal endothelial cells is associated with several difficulties. Human donor corneas are scarce and rarely available for ...

In Vivo Quantification of Hip Arthrokinematics during Dynamic Weight-bearing Activities using Dual Fluoroscopy

Several hip pathologies have been attributed to abnormal morphology with an underlying assumption of aberrant biomechanics. However, structure-function relationships at the joint level remain challenging to quantify due to difficulties in accurately measuring dynamic joint motion. The soft tissue artifact errors inherent in optical skin marker motion capture are exacerbated by the depth of the hip joint within the body and the large mass of soft tissue surrounding the joint. Thus, the complex relationship between bone shape and hip joint kinematics is more difficult to study accurately than in other joints. Herein, a protocol incorporating computed tomography (CT) arthrography, three-dimensional (3D) reconstruction of volumetric images, dual fluoroscopy, and optical motion capture to accurately measure the dynamic motion of the hip joint is presented. The technical and clinical studies that have applied dual fluoroscopy to study form-function relationships of the hip using this protocol are summarized, and the specific steps and future considerations for data acquisition, processing, and analysis are described.

In Vivo Quantification of Hip Arthrokinematics during Dynamic Weight-bearing Activities using Dual Fluoroscopy

Dual fluoroscopy accurately captures in vivo dynamic motion of human joints, which can be visualized relative to reconstructed anatomy (e.g., arthrokinematics). Herein, a detailed protocol to quantify hip arthrokinematics during weight-bearing activities of daily living is presented, including the integration of dual fluoroscopy with traditional skin marker motion capture.

In vivo Cuantificación de la artrocinamática de cadera durante las actividades dinámicas de soporte de peso mediante fluoroscopia dual

Several hip pathologies have been attributed to abnormal morphology with an underlying assumption of aberrant biomechanics. However, structure-function ...

Modified Posterior Vertebral Column Resection for Patients with Thoracolumbar Kyphotic Deformity

Old compression vertebrae fracture or congenital kyphoscoliosis with abnormal vertebral body development and other diseases that invade the spine may cause severe thoracolumbar kyphotic deformity, often accompanied by intractable low back pain or compression of the spinal cord, leading to severe neurological symptoms or even paralysis. If conservative treatment cannot relieve the symptoms or correct the deformities, surgical treatment is usually needed. For severe kyphotic deformity, reconstruction of the physiological curvature and rigid fixation determine the prognosis of the patients. Osteotomy and orthopedics are the standard procedure for deformities with severe compression of the front and middle column, but the trauma to the patients is high, with a long operation time and massive blood loss. To avoid these disadvantages, we have developed a modified technique to remove the diseased vertebra unilaterally. In this technique, we use a modified trephine to resect the vertebral columns like in the pedicle screw technique by adding a locking instrument that can restrict the trephine to lower the risk of osteotomy and shorten the surgery time and blood loss.

We describe a modified technique for resecting the posterior vertebral column unilaterally based on a modified trephine for patients with thoracolumbar kyphotic deformity.

Resección modificada de la columna vertebral posterior para pacientes con deformidad cifótica toracolumbar

Old compression vertebrae fracture or congenital kyphoscoliosis with abnormal vertebral body development and other diseases that invade the spine may ...