Pallav Kolli，法比奥Settecase，马修·阿芒，和罗伯特·泰勒从加州大学旧金山分校，宾夕法尼亚大学的蒂姆·罗伯茨资金来源美国国立卫生研究院国家心肺血液研究所（NHLBI）奖（M.威尔逊）：1R01HL076486美国社会的神经放射学研究和教育基金会的学者奖（S. Hetts） 美国国立卫生研究院国家生物医学成像和生物工程研究所（NIBIB）奖（S. Hetts）：1R01EB012031

1。弹簧圈的制作<ol><li>获取（ 例如 2.3F捷运科迪斯血管神经导管，雷纳姆，MA）基板市售微导管。 </li><li>确保导管有没有铁的成分，被认为是安全MR-，大小2.3-3.0的范围内F. </li><li>溅射的钛粘附层，然后由一个铜籽晶层，直到1至2毫米外径绝缘管。可能的材料包括聚酰亚胺或氧化铝（Ortech高级陶瓷，萨克拉门托，CA）。 </li><li>电沉积一个正的光致抗蚀剂层，使用希普利的PEPR-2400（目前正在由DOW化学公司出售的名称下Intervia 3D-P）。在一个均匀的涂层的非平面的圆柱形表面上的电沉积的结果。 </li><li>光致抗蚀剂暴露的独特的激光直写系统（激光车床，在劳伦斯·利弗莫尔国家实验室开发的一个非商业化的系统）所需的线圈形式的格局（ 图2A）。这是一个修饰该技术的重刑最初描述14在MALBA 等。 </li><li>发展的曝光的光致抗蚀剂，在碳酸钾的1％溶液在35℃下</li><li>铜电镀通过其它的抗蚀剂掩模，以形成所需的线圈。该系统可以制造两个电磁和亥姆霍兹（跑道）的铜图案（ 图2C和2D）。 </li><li>铜电后，除去抗蚀剂与热开发。拆下的铜籽晶层，然后由钛粘附层。 </li><li>将绝缘管，导管尖端使用收缩包装完成组装。确保收缩包装涵盖了整个盘绕提示。 ，为了组装多轴导管放置彼此内的绝缘管的结构，如在图2E所示。 </li><li>螺纹铜线通过微型导管和焊料的尖端处的线圈的内腔。 </li><li>修改和缩短6英尺RJ11电话线吨O 3英尺长。 </li><li>连接从后端枢纽的微型导管发出的改性3英尺插口传输线的铜线。 </li></ol> 2。水浴设置<ol><li>做一个小的约5厘米的塑料盆从底部的侧孔的中心。 </li><li>通过孔插入一个9F阿凡提科迪斯血管鞘（科迪斯血管内，佛罗里达州迈阿密湖）。 </li><li>切的的血管鞘留下一个4厘米长的片延伸，向盆地的远端头。 </li><li>在端部的鞘中，附加的旋转-止血或Thuoy的一下Borst阀稳定的微导管的位置。 </li><li>在蒸馏水确保完全淹没的设备填写盆。 </li><li>带有螺旋头插入导管通过血管鞘和阀门。 </li><li>测量和记录的微导管从阀延伸到水浴奔放长度。 </li><li>将水浴微MR扫描仪和定向相对于磁体的孔中的磁体的内导管系统。 </li><li>将修改后的3英尺电话线连接的导管，以一个25英尺RJ11电话线传输线使用了2路耳机插孔。 </li><li>的25英尺电话线的另一端​​连接一个Lambda的LPD-422A-FM双稳压的电力供应提供到设备的电流高达1 A。 </li><li>将通过的波导管和电源的MR扫描室以外的5高斯线以外的传输线。 </li></ol> 3。船舶幻影设置<ol><li>实验之前从橡胶管与一个Y形的交叉点，构建的中空容器幻像。 </li><li>填充容器幻像用0.0102 M溶液在蒸馏水中的马根维显（GdDTPA）的（马根维显，拜耳医疗保健药品，蒙特维尔，新泽西）创建幻象船只和背景之间的对比度。 </li><li>组装的MicroCatheter系统，步骤1.1到1.9中概述的。导管连接到在步骤2.9至2.11所述的电源供应器及位置。 </li><li>在容器开口部的基础上的微导管的前端的位置。 </li><li>内放置的幻像MR扫描仪和定向的磁体相对于磁体的孔中。 </li></ol> 4。磁共振成像<ol><li>与1.5T的，临床磁共振系统（西门子Avanto，SW，德国埃尔兰根的syngo B13，飞利浦Achieva，软件版本2.1，克利夫兰，OH）进行成像。 </li><li>套用&lt;50 mA的电流，以可视化的导管尖端位置。根据MRI，一个小磁矩将在导管尖端看到一个明显的不同形状的工件，这取决于线圈通电。 </li><li>应用可变数量的电流在±100毫安的范围内的Lambda双电源线圈尖端偏转（ 图3A-3C），并观察在水中巴日设置。由于尖偏转几乎是瞬间，只适用于当前〜1-2秒，以可视化的最大挠度。 </li><li>重复记录连续的应用程序的设置大量的电流。 </li><li>重复步骤4.2允许机械提高至容器内，虚线（ 图4A和4B）的手工同时推导管。应用当前的分支点处，以使导管尖端偏转成所需的容器。推进到分支血管导管通过手动推的导管的端部（ 图4C）。缩回导管的血管分叉和重复相反的分支（ 图4D）。 </li><li>掌握使用2D快照FLASH序列（TR = 30毫秒，TE = 1.4毫秒，256 128倍的矩阵和翻转角〜30°）的MR图像。 </li></ol> 5。挠度测量期间捕获的图像分析和测量角度的偏转水浴实验与计算机应用（任何一个数字成像和通信医学（DICOM）浏览器）。

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博士Hetts已收到授予史赛克公司的支持，是丝绸之路医药公司的有偿顾问

在这里，我们描述偏转的微导管在MR扫描仪的协议。成功的关键参数是准确的电流和测量应用的偏转角。测量不准确的偏转角是在该协议中最有可能遇到的错误。 MR图像捕获期间水浴实验的角度可能不同于实际值，由于轻微的排列方向不同，该媒介相对于磁体的孔中定位。为了解决这个问题，在未来，可以拍摄的影像通过MR-兼容的光纤相机定位在两个不同的层面。两个MR和摄像头图像的使用，将提...

血管内介入医学用X射线指导导管通过血管治疗的几大疾病，如脑血管瘤，缺血性中风，实体瘤，动脉粥样硬化和心律失常针对超过一百万患者每年全球1导航的工具程序- 5。随着造影剂的使用，导航通过脉管系统通过手动旋转的导管和机械进步实现由干预的手6。然而，通过曲折的小血管周围有许多血管弯曲的导航变得越来越困难，延长的时间才到达目标网站。这就提出了一个问题，对时间敏感的程序，如去除血块阻塞血管。此外，长时间手术增加的辐射剂量，并创造出有潜力的不良事件7-11。然而，血管内的程序下进行磁化C谐振成像可能提供一种解决方案。 强大的均匀磁场的核磁共振成像扫描仪可以利用导管尖端导航遥控12,13。电流施加到导管尖端位于microcoil诱导磁矩小，因为它对准的MRI扫描仪13（ 图1）的孔中，经历了转矩。如果电流在一个单独的线圈被激活，导管尖端可以通过远程控制在一个平面内偏转。如果在导管尖端的三个线圈通电时，可以实现在导管尖端偏转三维。因此，磁推动转向导管有可能增加血管在血管内手术导航的速度和有效性，这可以减少手术时间，改善患者的预后。在这项研究中，我们研究了如果当前应用到microcoil头的血管内导管，可产生可靠的和可控的挠度附加的领导下，指导导管导航研究的初步测试。

<table border="1">
<tbody>
 <tr>
 <td>Name of Reagent/Material</td>
 <td>Company</td>
 <td>Catalog Number</td>
 <td>Comments</td>
 </tr>
 <tr>
 <td>GdDTPA Contrast Media (Magnevist)</td>
 <td>Bayer HealthCare Pharmaceuticals Inc. </td>
 <td>1240340</td>
 <td>McKesson Material Number</td>
 </tr>
 <tr>
 <td>Positive Photoresist</td>
 <td>Shipley</td>
 <td>N/A</td>
 <td>PEPR-2400, Replacement: Dow Chemicals Intervia 3D-P </td>
 </tr>
 <tr>
 <td>Copper Sulfate</td>
 <td>ScienceLab</td>
 <td>SLC3778</td>
 <td>Crystal form</td>
 </tr>
 <tr>
 <td>Sulfuric Acid</td>
 <td>ScienceLab</td>
 <td>SLS1573</td>
 <td>50% w/w solution</td>
 </tr>
 <tr>
 <td>Parrafin Wax</td>
 <td>Carolina</td>
 <td>879190</td>
 <td></td>
 </tr>
 <tr>
 <td>Potassium Carbonate </td>
 <td>Acros Organics</td>
 <td>424081000</td>
 <td></td>
 </tr>
</tbody>
 </table>

magnetically-assisted remote controlled microcatheter tip deflection under magnetic resonance imaging

X线透视引导下血管内的程序有几个显着的限制，包括难以的导管导航和利用电离辐射，可能会被克服MR指导下使用磁性可控的导管。 这项工作的主要目的是开发一种微导管，其尖端使用磁场的MR扫描仪，可以远程控制。该协议的目的是描述的程序申请的microcoil头微导管一贯的，可控的变形。 制作中，采用激光车床光刻技术的一个microcoil到聚酰亚胺头的血管内导管。一个1.5-T磁共振系统的稳态自由进动（SSFP）测序的指导下， 在体外试验中进行水浴中和容器幻象。不同量的电流施加到线圈的微型导管，以产生测量sureable提示的挠度和导航的血管幻影。 此设备的发展提供了一个平台，为未来的测试和革命性的血管内介入MRI环境的机会。

应该观察到从协议如上所述，在0度和90度之间的偏转角，从应用程序同时交付到一个合并的螺线管和亥姆霍兹线圈微型导管系统（ 图2E）的两个线圈的电流为50-300毫安。应当施加的电流的增加导致在微型导管的偏转角的增加，电流的极性反转而导致的偏转与正电流在完全相反的方向上所观察到的（ 图5A-5C）。的偏转角，但是，是依赖于几个参数。施加的电流的量，并在电...

Watch this Scientific Journal Video about Magnetically-Assisted Remote Controlled Microcatheter Tip Deflection under Magnetic Resonance Imaging at JoVE.com

Magnetically-Assisted Remote Controlled Microcatheter Tip Deflection under Magnetic Resonance Imaging

电流施加到血管内的微导管通过激光车床光刻microcoil小费可以实现可控挠度根据磁共振（MR）的指导，这可以改善在各种血管内手术导航中的​​脉管系统的速度和疗效。

磁力辅助的远程控制微导管尖端偏转根据磁共振成像

X-ray fluoroscopy-guided  endovascular procedures have several significant limitations, including  difficult catheter navigation and use of ionizing ...

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12.3K 次观看.  University of California, San Francisco. 电流施加到血管内的微导管通过激光车床光刻microcoil小费可以实现可控挠度根据磁共振（MR）的指导，这可以改善在各种血管内手术导航中的​​脉管系统的速度和疗效。

视频: Magnetically-Assisted Remote Controlled Microcatheter Tip Deflection under Magnetic Resonance Imaging

Magnetic Resonance Elastography Methodology for the Evaluation of Tissue Engineered Construct Growth

Traditional mechanical testing often results in the destruction of the sample, and in the case of long term tissue engineered construct studies, the use of destructive assessment is not acceptable. A proposed alternative is the use of an imaging process called magnetic resonance elastography. Elastography is a nondestructive method for determining the engineered outcome by measuring local mechanical property values (i.e., complex shear modulus), which are essential markers for identifying the structure and functionality of a tissue. As a noninvasive means for evaluation, the monitoring of engineered constructs with imaging modalities such as magnetic resonance imaging (MRI) has seen increasing interest in the past decade1. For example, the magnetic resonance (MR) techniques of diffusion and relaxometry have been able to characterize the changes in chemical and physical properties during engineered tissue development2. The method proposed in the following protocol uses microscopic magnetic resonance elastography (&mu;MRE) as a noninvasive MR based technique for measuring the mechanical properties of small soft tissues3. MRE is achieved by coupling a sonic mechanical actuator with the tissue of interest and recording the shear wave propagation with an MR scanner4. Recently, &mu;MRE has been applied in tissue engineering to acquire essential growth information that is traditionally measured using destructive mechanical macroscopic techniques5. In the following procedure, elastography is achieved through the imaging of engineered constructs with a modified Hahn spin-echo sequence coupled with a mechanical actuator. As shown in Figure 1, the modified sequence synchronizes image acquisition with the transmission of external shear waves; subsequently, the motion is sensitized through the use of oscillating bipolar pairs. Following collection of images with positive and negative motion sensitization, complex division of the data produce a shear wave image. Then, the image is assessed using an inversion algorithm to generate a shear stiffness map6. The resulting measurements at each voxel have been shown to strongly correlate (R2&gt;0.9914) with data collected using dynamic mechanical analysis7. In this study, elastography is integrated into the tissue development process for monitoring human mesenchymal stem cell (hMSC) differentiation into adipogenic and osteogenic constructs as shown in Figure 2.

The procedure demonstrates the methodology of magnetic resonance elastography for monitoring the engineered outcome of adipose and osteogenic tissue engineered constructs through noninvasive local assessment of the mechanical properties using microscopic magnetic resonance elastography (&mu;MRE).

磁共振弹性成像方法评价组织工程构造增长

Traditional mechanical testing often results in the destruction of the sample, and in the case of long term tissue engineered construct studies, the use ...

科研

生物工程

Remote Magnetic Actuation of Micrometric Probes for in situ 3D Mapping of Bacterial Biofilm Physical Properties

Bacterial adhesion and growth on interfaces lead to the formation of three-dimensional heterogeneous structures so-called biofilms. The cells dwelling in these structures are held together by physical interactions mediated by a network of extracellular polymeric substances. Bacterial biofilms impact many human activities and the understanding of their properties is crucial for a better control of their development &#8212; maintenance or eradication &#8212; depending on their adverse or beneficial outcome. This paper describes a novel methodology aiming to measure in situ the local physical properties of the biofilm that had been, until now, examined only from a macroscopic and homogeneous material perspective. The experiment described here&#160;involves introducing magnetic particles into a growing biofilm to seed local probes that can be remotely actuated without disturbing the structural properties of the biofilm. Dedicated magnetic tweezers were developed to exert a defined force on each particle embedded in the biofilm. The setup is mounted on the stage of a microscope to enable the&#160;recording of time-lapse images of the particle-pulling period. The particle trajectories are then extracted from the pulling sequence and the local viscoelastic parameters are derived from each particle displacement curve, thereby providing the 3D-spatial distribution of the parameters. Gaining insights into the biofilm mechanical profile is essential from an engineer&#39;s point of view for biofilm control purposes but also from a fundamental perspective to clarify the relationship between the architectural properties and the specific biology of these structures.

Remote Magnetic Actuation of Micrometric Probes for in situ 3D Mapping of Bacterial Biofilm Physical Properties

This paper shows an original methodology based on the remote actuation of magnetic particles seeded in a bacterial biofilm and the development of dedicated magnetic tweezers to measure in situ the local mechanical properties of the complex living material built by micro-organisms at interfaces.

测微探针进行远程磁驱动<em&gt;原位</em&gt; 3D细菌生物膜物理性质的映射

Bacterial adhesion and growth on interfaces lead to the formation of three-dimensional heterogeneous structures so-called biofilms. The cells dwelling in ...

Custom-designed Laser-based Heating Apparatus for Triggered Release of Cisplatin from Thermosensitive Liposomes with Magnetic Resonance Image Guidance

Liposomes have been employed as drug delivery systems to target solid tumors through exploitation of the enhanced permeability and retention (EPR) effect resulting in significant reductions in systemic toxicity. Nonetheless, insufficient release of encapsulated drug from liposomes has limited their clinical efficacy. Temperature-sensitive liposomes have been engineered to provide site-specific release of drug in order to overcome the problem of limited tumor drug bioavailability. Our lab has designed and developed a heat-activated thermosensitive liposome formulation of cisplatin (CDDP), known as HTLC, to provide triggered release of CDDP at solid tumors. Heat-activated delivery in vivo was achieved in murine models using a custom-built laser-based heating apparatus that provides a conformal heating pattern at the tumor site as confirmed by MR thermometry (MRT). A fiber optic temperature monitoring device was used to measure the temperature in real-time during the entire heating period with online adjustment of heat delivery by alternating the laser power. Drug delivery was optimized under magnetic resonance (MR) image guidance by co-encapsulation of an MR contrast agent (i.e.,&#160;gadoteridol) along with CDDP into the thermosensitive liposomes as a means to validate the heating protocol and to assess tumor accumulation. The heating protocol consisted of a preheating period of 5 min prior to administration of HTLC and 20 min heating post-injection. This heating protocol resulted in effective release of the encapsulated agents with the highest MR signal change observed in the heated tumor in comparison to the unheated tumor and muscle. This study demonstrated the successful application of the laser-based heating apparatus for preclinical thermosensitive liposome development and the importance of MR-guided validation of the heating protocol for optimization of drug delivery.

AN MRI-compatible&#160;custom-designed laser-based heating apparatus has been developed to provide local heating of subcutaneous tumors in order to activate release of agents from thermosensitive liposomes specifically at the tumor region.

定制设计的基于激光的加热装置顺铂触发释放的热敏脂质体与磁共振成像制导

Liposomes have been employed as drug delivery systems to target solid tumors through exploitation of the enhanced permeability and retention (EPR) effect ...

Alternating Magnetic Field-Responsive Hybrid Gelatin Microgels for Controlled Drug Release

Magnetically-responsive nano/micro-engineered biomaterials that enable a tightly controlled, on-demand drug delivery have been developed as new types of smart soft devices for biomedical applications. Although a number of magnetically-responsive drug delivery systems have demonstrated efficacies through either in vitro proof of concept studies or in vivo preclinical applications, their use in clinical settings is still limited by their insufficient biocompatibility or biodegradability. Additionally, many of the existing platforms rely on sophisticated techniques for their fabrications. We recently demonstrated the fabrication of biodegradable, gelatin-based thermo-responsive microgel by physically entrapping poly(N-isopropylacrylamide-co-acrylamide) chains as a minor component within a three-dimensional gelatin network. In this study, we present a facile method to fabricate a biodegradable drug release platform that enables a magneto-thermally triggered drug release. This was achieved by incorporating superparamagnetic iron oxide nanoparticles and thermo-responsive polymers within gelatin-based colloidal microgels, in conjunction with an alternating magnetic field application system.

We present a facile method to fabricate a biodegradable gelatin-based drug release platform that is magneto-thermally responsive. This was achieved by incorporating superparamagnetic iron oxide nanoparticles and poly(N-isopropylacrylamide-co-acrylamide) within a spherical gelatin micro-network crosslinked by genipin, in conjunction with an alternating magnetic field application system.

交变磁场敏感的混合明胶微凝胶药物控释

Magnetically-responsive nano/micro-engineered biomaterials that enable a tightly controlled, on-demand drug delivery have been developed as new types of ...

Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters In Vivo

We demonstrate a superior method of 2D spectral-spatial imaging of stable radical reporter molecules at 250 MHz using rapid-scan electron-paramagnetic-resonance (RS-EPR), which can provide quantitative information under in vivo conditions on oxygen concentration, pH, redox status and concentration of signaling molecules (i.e., OH&#8226;, NO&#8226;). The RS-EPR technique has a higher sensitivity, improved spatial resolution (1 mm), and shorter acquisition time in comparison to the standard continuous wave (CW) technique. A variety of phantom configurations have been tested, with spatial resolution varying from 1 to 6 mm, and spectral width of the reporter molecules ranging from 16 &#181;T (160 mG) to 5 mT (50 G). A cross-loop bimodal resonator decouples excitation and detection, reducing the noise, while the rapid scan effect allows more power to be input to the spin system before saturation, increasing the EPR signal. This leads to a substantially higher signal-to-noise ratio than in conventional CW EPR experiments.

Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters In Vivo

A new electron paramagnetic resonance (EPR) method, rapid scan EPR (RS-EPR), is demonstrated for 2D spectral spatial imaging which is superior to the traditional continuous wave (CW) technique and opens new venues for in vivo imaging. Results are demonstrated at 250 MHz, but the technique is applicable at any frequency.

快速扫描电子顺磁共振打开新的途径成像生理重要参数<em&gt;在体内</em

We demonstrate a superior method of 2D spectral-spatial imaging of stable radical reporter molecules at 250 MHz using rapid-scan ...

Magnetic Levitation Coupled with Portable Imaging and Analysis for Disease Diagnostics

Currently, many clinical diagnostic procedures are complex, costly, inefficient, and inaccessible to a large population in the world. The requirements for specialized equipment and trained personnel require that many diagnostic tests be performed at remote, centralized clinical laboratories. Magnetic levitation is a simple yet powerful technique and can be applied to levitate cells, which are suspended in a paramagnetic solution and placed in a magnetic field, at a position determined by equilibrium between a magnetic force and a buoyancy force. Here, we present a versatile platform technology designed for point-of-care diagnostics which uses magnetic levitation coupled to microscopic imaging and automated analysis to determine the density distribution of a patient's cells as a useful diagnostic indicator. We present two platforms operating on this principle: (i) a smartphone-compatible version of the technology, where the built-in smartphone camera is used to image cells in the magnetic field and a smartphone application processes the images and to measures the density distribution of the cells and (ii) a self-contained version where a camera board is used to capture images and an embedded processing unit with attached thin-film-transistor (TFT) screen measures and displays the results. Demonstrated applications include: (i) measuring the altered distribution of a cell population with a disease phenotype compared to a healthy phenotype, which is applied to sickle cell disease diagnosis, and (ii) separation of different cell types based on their characteristic densities, which is applied to separate white blood cells from red blood cells for white blood cell cytometry. These applications, as well as future extensions of the essential density-based measurements enabled by this portable, user-friendly platform technology, will significantly enhance disease diagnostic capabilities at the point of care.

We present a magnetic levitation technique coupled with automated imaging and analysis in both a smartphone-compatible device and a device with embedded imaging and processing. This is applied to measure the density distribution of cells with two demonstrated biomedical applications: sickle cell disease diagnosis and separating white and red blood cells.

磁悬浮加上便携式成像与分析诊断疾病

Currently, many clinical diagnostic procedures are complex, costly, inefficient, and inaccessible to a large population in the world. The requirements for ...

Magnetic and Thermal-sensitive Poly(N-isopropylacrylamide)-based Microgels for Magnetically Triggered Controlled Release

Magnetically and thermally sensitive poly(N-isopropylacrylamide) (PNIPAAm)/Fe3O4-NH2 microgels with the encapsulated anti-cancer drug curcumin (Cur) were designed and fabricated for magnetically triggered release. PNIPAAm-based magnetic microgels with a spherical structure were produced via a temperature-induced emulsion followed with physical-crosslinking by mixing PNIPAAm, polyethylenimine (PEI), and Fe3O4-NH2 magnetic nanoparticles. Because of their dispersity, the Fe3O4-NH2 nanoparticles were embedded inside the polymer matrix. The amine groups exposed on the Fe3O4-NH2 and PEI surface supported the spherical structure by physically crosslinking with the amide groups of the PNIPAAm. The hydrophobic anti-cancer drug curcumin can be dispersed in water after encapsulation into the microgels. The microgels were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and UV-Vis spectral analysis. Furthermore, magnetically triggered release was studied under an external high frequency magnetic field (HFMF). A significant &#34;burst release&#34; of curcumin was observed after applying the HFMF to the microgels due to the magnetic inductive heating (hyperthermia) effect. This manuscript describes the magnetically triggered controlled release of Cur-PNIPAAm/Fe3O4-NH2 encapsulated curcumin, which can be potentially applied for tumor therapy.

Magnetic and Thermal-sensitive PolyN-isopropylacrylamide-based Microgels for Magnetically Triggered Controlled Release

This manuscript describes the preparation of magnetic and thermal-sensitive microgels via a temperature-induced emulsion without chemical reaction. These sensitive microgels were synthesized by mixing poly(N-isopropylacrylamide) (PNIPAAm), polyethylenimine (PEI) and Fe3O4-NH2 nanoparticles for the potential use in magnetically and thermally triggered drug-release.

磁性和热敏性聚（<em&gt;ñ</em基于异丙基丙烯酰胺）的微凝胶用于磁触发控制释放

Magnetically and thermally sensitive poly(N-isopropylacrylamide) (PNIPAAm)/Fe3O4-NH2 microgels with the encapsulated anti-cancer drug curcumin (Cur) were ...

Metabolic Support of Excised, Living Brain Tissues During Magnetic Resonance Microscopy Acquisition

This protocol describes the procedures necessary to support normal metabolic functions of acute brain slice preparations during the collection of magnetic resonance (MR) microscopy data. While it is possible to perform MR collections on living, excised mammalian tissue, such experiments have traditionally been constrained by resolution limits and are thus incapable of visualizing tissue microstructure. Conversely, MR protocols that did achieve microscopic image resolution required the use of fixed samples to accommodate the need for static, unchanging conditions over lengthy scan times. The current protocol describes the first available MR technique that enables imaging of living, mammalian tissue samples at microscopic resolutions. Such data is of great importance to the understanding of how pathology-based contrast changes occurring at the microscopic level influence the content of macroscopic MR scans such as those used in the clinic. Once such an understanding is realized, diagnostic methods with greater sensitivity and accuracy can be developed, which will translate directly to earlier disease treatment, more accurate therapy monitoring and improved patient outcomes.
While the described methodology focuses on brain slice preparations, the protocol is adaptable to any excised tissue slice given that changes are made to the gas and perfusate preparations to accommodate the tissue&#39;s specific metabolic needs. Successful execution of the protocol should result in living, acute slice preparations that exhibit MR diffusion signal stability for periods up to 15.5 h. The primary advantages of the current system over other MR compatible perfusion apparatuses are its compatibility with the MR microscopy hardware required to attain higher resolution images and ability to provide constant, uninterrupted flow with carefully regulated perfusate conditions. Reduced sample throughput is a consideration with this design as only one tissue slice may be imaged at a time.

The current protocol describes a method by which users can maintain viability of acute hippocampal and cortical slice preparations during the collection of magnetic resonance microscopy data.

磁共振显微镜下切除活体脑组织的代谢支持

This protocol describes the procedures necessary to support normal metabolic functions of acute brain slice preparations during the collection of magnetic ...

Measuring the Spin-Lattice Relaxation Magnetic Field Dependence of Hyperpolarized [1-13C]pyruvate

The fundamental limit to in vivo imaging applications of hyperpolarized 13C-enriched compounds is their finite spin-lattice relaxation times. Various factors affect the relaxation rates, such as buffer composition, solution pH, temperature, and magnetic field. In this last regard, the spin-lattice relaxation time can be measured at clinical field strengths, but at lower fields, where these compounds are dispensed from the polarizer and transported to the MRI, the relaxation is even faster and difficult to measure. To have a better understanding of the amount of magnetization lost during transport, we used fast field-cycling relaxometry, with magnetic resonance detection of 13C nuclei at ~0.75 T, to measure the nuclear magnetic resonance dispersion of the spin-lattice relaxation time of hyperpolarized [1-13C]pyruvate. Dissolution dynamic nuclear polarization was used to produce hyperpolarized samples of pyruvate at a concentration of 80 mmol/L and physiological pH (~7.8). These solutions were rapidly transferred to a fast field-cycling relaxometer so that relaxation of the sample magnetization could be measured as a function of time using a calibrated small flip angle (3&#176;-5&#176;). To map the T1 dispersion of the C-1 of pyruvate, we recorded data for different relaxation fields ranging between 0.237 mT and 0.705 T. With this information, we determined an empirical equation to estimate the spin-lattice relaxation of the hyperpolarized substrate within the mentioned range of magnetic fields. These results can be used to predict the amount of magnetization lost during transport and to improve experimental designs to minimize signal loss.

Measuring the Spin-Lattice Relaxation Magnetic Field Dependence of Hyperpolarized [1-13C]pyruvate

We present a protocol to measure the magnetic field dependence of the spin-lattice relaxation time of 13C-enriched compounds, hyperpolarized by means of dynamic nuclear polarization, using fast field-cycled relaxometry. Specifically, we have demonstrated this with [1-13C]pyruvate, but the protocol could be extended to other hyperpolarized substrates.

测量超极化 [1-13C]硫化的旋转-莱迪兹松弛磁场依赖性

The fundamental limit to in vivo imaging applications of hyperpolarized 13C-enriched compounds is their finite spin-lattice relaxation times. Various ...

High-resolution Imaging of Nuclear Dynamics in Live Cells under Uniaxial Tensile Strain

Extracellular mechanical strain is known to elicit cell phenotypic responses and has physiological relevance in several tissue systems. To capture the effect of applied extracellular tensile strain on cell populations in vitro via biochemical assays, a device has previously been designed which can be fabricated simply and is small enough to fit inside tissue culture incubators, as well as on top of microscope stages. However, the previous design of the polydimethylsiloxane substratum did not allow high-resolution subcellular imaging via oil-immersion objectives. This work describes a redesigned geometry of the polydimethylsiloxane substratum and a customized imaging setup that together can facilitate high-resolution subcellular imaging of live cells while under applied strain. This substratum can be used with the same, earlier designed device and, hence, has the same advantages as listed above, in addition to allowing high-resolution optical imaging. The design of the polydimethylsiloxane substratum can be improved by incorporating a grid which will facilitate tracking the same cell before and after the application of strain. Representative results demonstrate high-resolution time-lapse imaging of fluorescently labeled nuclei within strained cells captured using the method described here. These nuclear dynamics data give insights into the mechanism by which applied tensile strain promotes differentiation of oligodendrocyte progenitor cells.&#160;

Using a previously designed device to apply mechanical strain to adherent cells, this paper describes a redesigned substratum geometry and a customized apparatus for high-resolution single-cell imaging of strained cells with a 100x oil immersion objective.

单轴拉伸应变下活细胞核动力学的高分辨率成像

Extracellular mechanical strain is known to elicit cell phenotypic responses and has physiological relevance in several tissue systems. To capture the ...