这项工作是由全宗DE RECHERCHE SUR LA自然ET LES技术魁北克，加拿大创新研究院和加拿大卫生研究所（CIHR）fundation。

1。微细探针头（不显示在视频的过程） <ol><li>一个2硅晶片，4英寸直径，厚525微米，具有1微米厚的热的SiO2层，spincoated与光阻（PR）为在4000转45的小号。 </li><li>晶圆是在110C预焙为50秒，并通过一个5秒的所有元素（端口和微），直接投资开发和冲洗的掩码公开。 </li><li>发现二氧化硅是铭刻在一个1:7缓冲氢氟酸（BHF）≈15分钟（已铭刻二氧化硅基板去湿指示完成蚀刻）的解决方案。一个氧气等​​离子或丙酮用于灰或条状，其余的公关。 </li><li>第二公关层旋涂在1500转每分钟为45秒，产生了≈10微米[31]的厚重迭层。下面这个公关层SiO2的格局仍是可见的，用于晶圆，以配合第二只具有端口的掩码。 </li><li>晶圆曝光和发展的PR后，冲洗，干燥，并在95C postbaked 20分钟。 </li><li>硅晶片是连接到支持晶圆与融化的白蜡保护夹头。 </li><li>电感耦合等离子体（ICP）的DRIE是用于传输公关，并嵌入到晶圆地形三个步骤的过程中SiO2的模式： <ol><li>的DRIE，使之成为SI（厚公关定义的模式）≈500μmdeep端口。 </li><li>不卸载的DRIE机晶圆，公关是使用等离子灰化。 </li><li>暴露的二氧化硅模式作为第二个干法刻蚀过程的面具，创造50微米深的通道，开放晶圆灌装并通过排气孔。卸载后，支持晶圆下温水流是分离的。微加工晶圆，然后洗净后用丙酮，乙醇和DI。 </li></ol></li><li>个别MFP芯片泡。 </li><li> PDMS的接口块制造，铸造成两个结构聚（甲基丙烯酸甲酯）（PMMA）的元素，形成底部抛光的钢板，和两个毛细血管（分为两个通孔，访问的每个插入孔中组成一个micromould钢板）作为流体连接孔持有人。在60C烘箱固化硅橡胶是至少1小时。 </li><li>保税通过激活空气等离子在1毫巴24小号在230W的两个部分，并加入两者结合起来使用一个自制的机械对准一个泡MFP硅芯片的PDMS块。 </li><li>大会是在至少1小时的60C烤箱债券</li></ol> 2。大会在MFP <ol><li>不透气的玻璃注射器都充满了相应的试剂，使用塑料注射器和针头，以确保无气泡存在。通常情况下，我们使用了注入1日-10微升注射器，和一个较大的抽气量的5-10倍的注射器。 </li><li>注射器使用低死体积Nanotight配件连接到毛细管。 </li><li>毛细血管充满气泡，在显微镜下检查。 </li><li> MFP芯片与缓冲液，以防止泡沫诱捕连接的毛细血管时预填充。 </li><li>毛细血管探头插入硅橡胶连接件</li></ol> 3。 MFP的设置<ol><li>探头夹到探头支架和安装上盖倒置显微镜的探针台</li><li>放入高精度注射泵的注射器。 </li><li>的基板，如玻璃幻灯片，插入自制的持有人，即贴在显微镜阶段。 </li><li>通过观察牛顿环（干涉条纹）出现时，MFP与基板接触到使用的测角仪对MFP的台地和基板的并行调整。联系点和环的频率作为倾斜的迹象。当MFP与表面对齐，一个单一的干扰环遍及整个表面。这项措施也是校准MFP和基板之间的分离。 </li><li> MFP和基板之间的差距是表面图案进程的关键。由于基板是低于MFP扫描处理，水平对齐方式进行调整微米精度和使用三个点支撑，形成三个千分尺螺丝。 </li></ol> 4。 MFP的操作<ol><li>配药通过LabVIEW软件控制。设备操作是通过眼睛和使用CCD摄像头的可视化。注射：愿望的比例从1:3到1:10不等，取决于与周围的缓冲区和所需的几何流型试剂的扩散。 </li><li>要检查吸入注射器和存在泡沫的正常运作，首先与抽吸注射器注入液体，然后启动适当的共同愿望。</li><li>开始注射液和监视流量和珠或禁闭荧光示踪染料。 </li><li>探头使用特定的应用，即扫描整个表面处理沉积，蚀刻或表面或细胞染色。 </li></ol>

<ol>
	<li>Juncker, D., Schmid, H., Delamarche, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Nature Materials. 4 (8), 622-622 (2005).</li></ol>

微流体探头（MFP）是多才多艺的，因为它是（i）流动，（二）使用的试剂和底物的不同类型的适应性，它可以（三）大面积经营。 有害泡沫可能导致的流量，以防止气泡的破坏，所有的组件需要充满液体大会前。探头和表面之间的差距只有几微米，但梅萨是几百微米，宽，并在厘米范围内的扫描距离。因此，这两个横向扫描面和MFP的台面与基板之间的并行需要非常谨慎地调?...

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		<div>
		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>microfluidic connectors</td>
<td>&nbsp;</td>
<td>Upchurch Scientific</td>
<td>Micro- and Nano-tight fittings and sleeves</td>
<td>&nbsp;</td>
<tr>
<td>2-component manual dispenser</td>
<td>&nbsp;</td>
<td>Conprotec Inc.</td>
<td>DM400</td>
<td>To dispense and mix PDMS mixture</td>
</tr>
<tr>
<td>LabVIEW</td>
<td>&nbsp;</td>
<td>National Instruments</td>
<td>Version 8.0</td>
<td>&nbsp;</td>
<tr>
<td>Mechanical Convection Oven</td>
<td>&nbsp;</td>
<td>VWR</td>
<td>1330FM</td>
<td>&nbsp;</td>
<tr>
<td>Glass syringes</td>
<td>&nbsp;</td>
<td>Hamilton</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Capillary tubing</td>
<td>&nbsp;</td>
<td>Polymicro Technologies</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Plasma Chamber</td>
<td>&nbsp;</td>
<td>Tegal Corporation</td>
<td>Plasmaline 415</td>
<td>&nbsp;</td>
<tr>
<td>Inverted Microscope</td>
<td>&nbsp;</td>
<td>Nikon</td>
<td>TE2000-E</td>
<td>&nbsp;</td>
<tr>
<td>Syringe pumps</td>
<td>&nbsp;</td>
<td>Cetoni</td>
<td>neMESYS</td>
<td>&nbsp;</td>
<tr>
<td>Sylgard 184</td>
<td>&nbsp;</td>
<td>Ellsworth Adhesives</td>
<td>184 Sil Elast Kit</td>
<td>&nbsp;</td>
<tr>
<td>Camera</td>
<td>&nbsp;</td>
<td>Photometrics</td>
<td>QuantEM 512SC</td>
<td>&nbsp;</td>
<tr>
<td>Microscope stage</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Microfluidic probe holder goniometers</td>
<td>&nbsp;</td>
<td>Melles-Griot</td>
<td>07GON504</td>
<td>&nbsp;</td>
<tr>
<td>Linear stage</td>
<td>&nbsp;</td>
<td>Applied Scientific Instrumentation</td>
<td>LS-50</td>
<td>For z-control of the MFP</td>
</tr>
<tr>
<td>Manual linear stage</td>
<td>&nbsp;</td>
<td>Newport</td>
<td>443-4 Series</td>
<td>For x- and y- axis control of the MFP</td>
</tr>
<tr>
<td>Microscope stage</td>
<td>&nbsp;</td>
<td>Applied Scientific Instrumentation</td>
<td>PZ-2000</td>
<td>With x-, y- and z- control</td>
</tr>		</tbody>
		</table>
		</div>

the microfluidic probe: operation and use for localized surface processing

微流体装置允许使用微量的样品进行检测，最近被用来控制细胞的微环境。通常与微流体样品可以引进，并在培养细胞的情况下，在一个密闭的卷，封闭的，限制其使用的微。另一方面，micropipetting系统已用于本地灌注细胞和表面的，尤其是使用推挽设置，其中源和其他如水槽，但流动的禁闭吸管行为很难在三个方面。此外，吸液管是脆弱的，难以定位，因此，只使用静态配置。 微流体探头（MFP）避开封闭的微流体通道的建设和实施的限制，微流体流动，而不是封闭到微流体系统样品，可以直接传送到样品，并扫描整个样品，使用MFP。 。注射和愿望开口都设在一个几十微米，使注入的差距只限于一个微水刀周围的液体的水动力和完全吸气到其他开放。微水刀可以在基板表面被刷新，并提供了本地化的试剂可用于大面积扫描探针在表面上的沉积/交付精确的工具。在这个视频中，我们目前的微流控探头1（MFP ）。我们详细解释如何组装MFP，倒置显微镜上面安装，并对齐相对基板表面，并最终显示如何使用它的过程中衬底表面，沉浸在一个缓冲区。

Watch this Scientific Journal Video about The Microfluidic Probe: Operation and Use for Localized Surface Processing at JoVE.com

The Microfluidic Probe: Operation and Use for Localized Surface Processing

在这个视频中，我们目前微流体探头<sup&gt; 1</sup（MFP）。我们详细解释如何组装MFP，倒置显微镜上面安装，并对齐相对基板表面，并最终显示了如何使用它在缓冲溶液中浸泡处理基材表面。

微探针：操作和使用的局部表面处理

Microfluidic devices allow assays to be performed using minute amounts of sample and have recently been used to control the microenvironment of cells. ...

the-microfluidic-probe-operation-use-for-localized-surface

Research

JoVE Journal

Biology

8.8K 次观看.  McGill University. 在这个视频中，我们目前微流体探头 1

视频: The Microfluidic Probe: Operation and Use for Localized Surface Processing

Localized RNAi and Ectopic Gene Expression in the Medicinal Leech

In this video, we show the use of a pneumatic capillary gun for the accurate biolistic delivery of reagents into live tissue. We use the procedure to perturb gene expression patterns in selected segments of leech embryos, leaving the untreated segments as internal controls.
The pneumatic capillary gun can be used to reach internal layers of cells at early stages of development without opening the specimen. As a method for localized introduction of substances into living tissues, the biolistic delivery with the gun has several advantages: it is fast, contact-free and non-destructive. In addition, a single capillary gun can be used for independent delivery of different substances. The delivery region can have lateral dimensions of ~50-150 &#181;m and extends over ~15 &#181;m around the mean penetration depth, which is adjustable between 0 and 50 &#181;m. This delivery has the advantage of being able to target a limited number of cells in a selected location intermediate between single cell knock down by microinjection and systemic knockdown through extracellular injections or by means of genetic approaches.
For knocking down or knocking in the expression of the axon guidance molecule Netrin, which is naturally expressed by some central neurons and in the ventral body wall, but not the dorsal domain, we deliver molecules of dsRNA or plasmid-DNA into the body wall and central ganglia. This procedure includes the following steps: (i) preparation of the experimental setup for a specific assay (adjusting the accelerating pressure), (ii) coating the particles with molecules of dsRNA or DNA, (iii) loading the coated particles into the gun, up to two reagents in one assay, (iv) preparing the animals for the particle delivery, (v) delivery of coated particles into the target tissue (body wall or ganglia), and (vi) processing the embryos (immunostaining, immunohistochemistry and neuronal labeling) to visualize the results, usually 2 to 3 days after the delivery.
When the particles were coated with netrin dsRNA, they caused clearly visible knock-down of netrin expression that only occurred in cells containing particles (usually, 1-2 particles per cell). Particles coated with a plasmid encoding EGFP induced fluorescence in neuronal cells when they stopped in their nuclei.

In this video, we show a procedure for an accurate biolistic delivery of reagents into live tissue with a novel miniature gene gun. We are knocking down the expression of the axon guidance molecule Netrin in leech embryos by delivering molecules of dsRNA into the ventral body wall and ganglia of single segments.

本地化的RNAi和药用水蛭异位基因表达

In this video, we show the use of a pneumatic capillary gun for the accurate biolistic delivery of reagents into live tissue. We use the procedure to ...

科研

生物学

Fabrication and Operation of an Oxygen Insert for Adherent Cellular Cultures 

Oxygen is a key modulator of many cellular pathways, but current devices permitting in vitro oxygen modulation fail to meet the needs of biomedical research. The hypoxic chamber offers a simple system to control oxygenation in standard culture vessels, but lacks precise temporal and spatial control over the oxygen concentration at the cell surface, preventing its application in studying a variety of physiological phenomena. Other systems have improved upon the hypoxic chamber, but require specialized knowledge and equipment for their operation, making them intimidating for the average researcher. A microfabricated insert for multiwell plates has been developed to more effectively control the temporal and spatial oxygen concentration to better model physiological phenomena found in vivo. The platform consists of a polydimethylsiloxane insert that nests into a standard multiwell plate and serves as a passive microfluidic gas network with a gas-permeable membrane aimed to modulate oxygen delivery to adherent cells. The device is simple to use and is connected to gas cylinders that provide the pressure to introduce the desired oxygen concentration into the platform. Fabrication involves a combination of standard SU-8 photolithography, replica molding, and defined PDMS spinning on a silicon wafer. The components of the device are bonded after surface treatment using a hand-held plasma system. Validation is accomplished with a planar fluorescent oxygen sensor. Equilibration time is on the order of minutes and a wide variety of oxygen profiles can be attained based on the device design, such as the cyclic profile achieved in this study, and even oxygen gradients to mimic those found in vivo. The device can be sterilized for cell culture using common methods without loss of function. The device's applicability to studying the in vitro wound healing response will be demonstrated.

Fabrication and Operation of an Oxygen Insert for Adherent Cellular Cultures

Fabrication and validation of an add-on platform that offers enhanced control over the spatial and temporal oxygenation in a 6-well plate. The device is adaptable to a number of culture systems and can be used to investigate the effects of oxygen on wound healing.

为贴壁细胞培养的氧气插入的制备及操作

Oxygen is a key modulator of many cellular pathways, but current devices permitting in vitro oxygen modulation fail to meet the needs of biomedical ...

Biophysical Assays to Probe the Mechanical Properties of the Interphase Cell Nucleus: Substrate Strain Application and Microneedle Manipulation

In most eukaryotic cells, the nucleus is the largest organelle and is typically 2 to 10 times stiffer than the surrounding cytoskeleton; consequently, the physical properties of the nucleus contribute significantly to the overall biomechanical behavior of cells under physiological and pathological conditions. For example, in migrating neutrophils and invading cancer cells, nuclear stiffness can pose a major obstacle during extravasation or passage through narrow spaces within tissues.1 On the other hand, the nucleus of cells in mechanically active tissue such as muscle requires sufficient structural support to withstand repetitive mechanical stress. Importantly, the nucleus is tightly integrated into the cellular architecture; it is physically connected to the surrounding cytoskeleton, which is a critical requirement for the intracellular movement and positioning of the nucleus, for example, in polarized cells, synaptic nuclei at neuromuscular junctions, or in migrating cells.2 Not surprisingly, mutations in nuclear envelope proteins such as lamins and nesprins, which play a critical role in determining nuclear stiffness and nucleo-cytoskeletal coupling, have been shown recently to result in a number of human diseases, including Emery-Dreifuss muscular dystrophy, limb-girdle muscular dystrophy, and dilated cardiomyopathy.3 To investigate the biophysical function of diverse nuclear envelope proteins and the effect of specific mutations, we have developed experimental methods to study the physical properties of the nucleus in single, living cells subjected to global or localized mechanical perturbation. Measuring induced nuclear deformations in response to precisely applied substrate strain application yields important information on the deformability of the nucleus and allows quantitative comparison between different mutations or cell lines deficient for specific nuclear envelope proteins. Localized cytoskeletal strain application with a microneedle is used to complement this assay and can yield additional information on intracellular force transmission between the nucleus and the cytoskeleton. Studying nuclear mechanics in intact living cells preserves the normal intracellular architecture and avoids potential artifacts that can arise when working with isolated nuclei. Furthermore, substrate strain application presents a good model for the physiological stress experienced by cells in muscle or other tissues (e.g., vascular smooth muscle cells exposed to vessel strain). Lastly, while these tools have been developed primarily to study nuclear mechanics, they can also be applied to investigate the function of cytoskeletal proteins and mechanotransduction signaling.

We present two independent, microscope-based tools to measure the induced nuclear and cytoskeletal deformations in single, living adherent cells in response to global or localized strain application. These techniques are used to determine nuclear stiffness (i.e., deformability) and to probe intracellular force transmission between the nucleus and the cytoskeleton.

生物物理检测探头相间细胞核的力学性能：基材应变的应用和微针操纵

In most eukaryotic cells, the nucleus is the largest organelle and is typically 2 to 10 times stiffer than the surrounding cytoskeleton; consequently, the ...

Avidity-based Extracellular Interaction Screening (AVEXIS) for the Scalable Detection of Low-affinity Extracellular Receptor-Ligand Interactions

Extracellular protein:protein interactions between secreted or membrane-tethered proteins are critical for both initiating intercellular communication and ensuring cohesion within multicellular organisms. Proteins predicted to form extracellular interactions are encoded by approximately a quarter of human genes1, but despite their importance and abundance, the majority of these proteins have no documented binding partner. Primarily, this is due to their biochemical intractability: membrane-embedded proteins are difficult to solubilise in their native conformation and contain structurally-important posttranslational modifications. Also, the interaction affinities between receptor proteins are often characterised by extremely low interaction strengths (half-lives &lt; 1 second) precluding their detection with many commonly-used high throughput methods2. 
Here, we describe an assay, AVEXIS (AVidity-based EXtracellular Interaction Screen) that overcomes these technical challenges enabling the detection of very weak protein interactions (t1/2 &le; 0.1 sec) with a low false positive rate3. The assay is usually implemented in a high throughput format to enable the systematic screening of many thousands of interactions in a convenient microtitre plate format (Fig. 1). It relies on the production of soluble recombinant protein libraries that contain the ectodomain fragments of cell surface receptors or secreted proteins within which to screen for interactions; therefore, this approach is suitable for type I, type II, GPI-linked cell surface receptors and secreted proteins but not for multipass membrane proteins such as ion channels or transporters.
The recombinant protein libraries are produced using a convenient and high-level mammalian expression system4, to ensure that important posttranslational modifications such as glycosylation and disulphide bonds are added. Expressed recombinant proteins are secreted into the medium and produced in two forms: a biotinylated bait which can be captured on a streptavidin-coated solid phase suitable for screening, and a pentamerised enzyme-tagged (&beta;-lactamase) prey. The bait and prey proteins are presented to each other in a binary fashion to detect direct interactions between them, similar to a conventional ELISA (Fig. 1). The pentamerisation of the proteins in the prey is achieved through a peptide sequence from the cartilage oligomeric matrix protein (COMP) and increases the local concentration of the ectodomains thereby providing significant avidity gains to enable even very transient interactions to be detected. By normalising the activities of both the bait and prey to predetermined levels prior to screening, we have shown that interactions having monomeric half-lives of 0.1 sec can be detected with low false positive rates3.

Avidity-based Extracellular Interaction Screening AVEXIS for the Scalable Detection of Low-affinity Extracellular Receptor-Ligand Interactions

AVEXIS is a high throughput protein interaction assay developed to systematically screen for novel extracellular receptor-ligand pairs involved in cellular recognition processes. It is specifically designed to detect transient protein interactions that are difficult to identify using other high throughput approaches.

基于亲和力，外的相互作用筛选（AVEXIS）外低亲和力受体 - 配体相互作用的可扩展检测

Extracellular protein:protein interactions between secreted or membrane-tethered proteins are critical for both initiating intercellular communication and ...

The Use of Chemostats in Microbial Systems Biology

Cells regulate their rate of growth in response to signals from the external world. As the cell grows, diverse cellular processes must be coordinated including macromolecular synthesis, metabolism and ultimately, commitment to the cell division cycle. The chemostat, a method of experimentally controlling cell growth rate, provides a powerful means of systematically studying how growth rate impacts cellular processes - including gene expression and metabolism - and the regulatory networks that control the rate of cell growth. When maintained for hundreds of generations chemostats can be used to study adaptive evolution of microbes in environmental conditions that limit cell growth. We describe the principle of chemostat cultures, demonstrate their operation and provide examples of their various applications. Following a period of disuse after their introduction in the middle of the twentieth century, the convergence of genome-scale methodologies with a renewed interest in the regulation of cell growth and the molecular basis of adaptive evolution is stimulating a renaissance in the use of chemostats in biological research.

Cell growth rate is a regulated process and a primary determinant of cell physiology. Continuous culturing using chemostats enables extrinsic control of cell growth rate by nutrient limitation facilitating the study of molecular networks that control cell growth and how those networks evolve to optimize cell growth.

恒化器中微生物系统生物学中的应用

Cells regulate their rate of growth in response to signals from the external world. As the cell grows, diverse cellular processes must be coordinated ...

Intraductal Injection for Localized Drug Delivery to the Mouse Mammary Gland

Herein we describe a protocol to deliver various reagents to the mouse mammary gland via intraductal injections. Localized drug delivery and knock-down of genes within the mammary epithelium has been difficult to achieve due to the lack of appropriate targeting molecules that are independent of developmental stages such as pregnancy and lactation. Herein, we describe a technique for localized delivery of reagents to the mammary gland at any stage in adulthood via intraductal injection into the nipples of mice. The injections can be performed on live mice, under anesthesia, and allow for a non-invasive and localized drug delivery to the mammary gland. Furthermore, the injections can be repeated over several months without damaging the nipple. Vital dyes such as Evans Blue are very helpful to learn the technique. Upon intraductal injection of the blue dye, the entire ductal tree becomes visible to the eye. Furthermore, fluorescently labeled reagents also allow for visualization and distribution within the mammary gland. This technique is adaptable for a variety of compounds including siRNA, chemotherapeutic agents, and small molecules.

A protocol for the non-invasive intraductal delivery of aqueous reagents to the mouse mammary gland is described. The method takes advantage of localized injection into the nipples of mammary glands targeting mammary ducts specifically. This technique is adaptable for a variety of compounds including siRNA, chemotherapeutic agents and small molecules.

导管内注射局部给药的小鼠乳腺

Herein we describe a protocol to deliver various reagents to the mouse mammary gland via intraductal injections. Localized drug delivery and knock-down of ...

Probe-based Real-time PCR Approaches for Quantitative Measurement of microRNAs

Probe-based quantitative PCR (qPCR) is a favoured method for measuring transcript abundance, since it is one of the most sensitive detection methods that provides an accurate and reproducible analysis. Probe-based chemistry offers the least background fluorescence as compared to other (dye-based) chemistries. Presently, there are several platforms available that use probe-based chemistry to quantitate transcript abundance. qPCR in a 96 well plate is the most routinely used method, however only a maximum of 96 samples or miRNAs can be tested in a single run. This is time-consuming and tedious if a large number of samples/miRNAs are to be analyzed. High-throughput probe-based platforms such as microfluidics (e.g. TaqMan Array Card) and nanofluidics arrays (e.g. OpenArray) offer ease to reproducibly and efficiently detect the abundance of multiple microRNAs in a large number of samples in a short time. Here, we demonstrate the experimental setup and protocol for miRNA quantitation from serum or plasma-EDTA samples, using probe-based chemistry and three different platforms (96 well plate, microfluidics and nanofluidics arrays) offering increasing levels of throughput.

Circulating microRNAs have recently emerged as promising and novel biomarkers for various cancers and other diseases. The goal of this article is to discuss three different probe-based real-time PCR platforms and methods that are available to quantify and determine the abundance of circulating microRNAs.

基于探针实时荧光定量PCR途径的小分子RNA定量检测

Probe-based quantitative PCR (qPCR) is a favoured method for measuring transcript abundance, since it is one of the most sensitive detection methods that ...

Dried Blood Spots - Preparing and Processing for Use in Immunoassays and in Molecular Techniques

The idea of collecting blood on a paper card and subsequently using the dried blood spots (DBS) for diagnostic purposes originated a century ago. Since then, DBS testing for decades has remained predominantly focused on the diagnosis of infectious diseases especially in resource-limited settings or the systematic screening of newborns for inherited metabolic disorders and only recently have a variety of new and innovative DBS applications begun to emerge. For many years, pre-analytical variables were only inappropriately considered in the field of DBS testing and even today, with the exception of newborn screening, the entire pre-analytical phase, which comprises the preparation and processing of DBS for their final analysis has not been standardized. Given this background, a comprehensive step-by-step protocol, which covers al the essential phases, is proposed, i.e., collection of blood; preparation of blood spots; drying of blood spots; storage and transportation of DBS; elution of DBS, and finally analyses of DBS eluates. The effectiveness of this protocol was first evaluated with 1,762 coupled serum/DBS pairs for detecting markers of hepatitis B virus, hepatitis C virus, and human immunodeficiency virus infections on an automated analytical platform. In a second step, the protocol was utilized during a pilot study, which was conducted on active drug users in the German cities of Berlin and Essen.

The preparing and processing of dried blood spots (DBS) for their final analysis are still poorly standardized for most diagnostic applications. To overcome this shortcoming, a comprehensive step-by-step protocol is suggested and subsequently evaluated with regard to its effectiveness for detecting markers of viral infections.

干血斑点. 免疫和分子技术中使用的制备和加工

The idea of collecting blood on a paper card and subsequently using the dried blood spots (DBS) for diagnostic purposes originated a century ago. Since ...

Using Microfluidic Devices to Measure Lifespan and Cellular Phenotypes in Single Budding Yeast Cells

Budding yeast Saccharomyces cerevisiae is an important model organism in aging research. Genetic studies have revealed many genes with conserved effects on the lifespan across species. However, the molecular causes of aging and death remain elusive. To gain a systematic understanding of the molecular mechanisms underlying yeast aging, we need high-throughput methods to measure lifespan and to quantify various cellular and molecular phenotypes in single cells. Previously, we developed microfluidic devices to track budding yeast mother cells throughout their lifespan while flushing away newborn daughter cells. This article presents a method for preparing microfluidic chips and for setting up microfluidic experiments. Multiple channels can be used to simultaneously track cells under different conditions or from different yeast strains. A typical setup can track hundreds of cells per channel and allow for high-resolution microscope imaging throughout the lifespan of the cells. Our method also allows detailed characterization of the lifespan, molecular markers, cell morphology, and the cell cycle dynamics of single cells. In addition, our microfluidic device is able to trap a significant amount of fresh mother cells that can be identified by downstream image analysis, making it possible to measure the lifespan with higher accuracy.

This article presents a protocol optimized for the production of microfluidic chips and the setup of microfluidic experiments to measure the lifespan and cellular phenotypes of single yeast cells.

使用微流体装置来衡量寿命和细胞表型单芽殖酵母细胞

Budding yeast Saccharomyces cerevisiae is an important model organism in aging research. Genetic studies have revealed many genes with conserved effects ...

Partial Bile Duct Ligation in the Mouse: A Controlled Model of Localized Obstructive Cholestasis

In rodents, complete bile duct ligation (cBDL) of the common bile duct is an established surgical technique for studying obstructive cholestasis and bile duct proliferation. However, long-term experiments can lead to increased morbidity and mortality. In select mouse strains with underlying liver disease, meaningful comparisons can be made even with ligation of a single lobe of the liver, which can reduce animal losses and expenses. Here, we describe partial bile duct ligation (pBDL) in the mouse, in which only the left hepatic bile duct is ligated, causing biliary obstruction in the left lobe but not the remaining lobes. With careful microsurgical technique, pBDL experiments can be cost-effective, since the unligated lobe serves as an internal control to the ligated lobes, when subjected to the same conditions in the same animal. Unlike cBDL, a separate sham-operated control group is not necessary. pBDL is highly useful to directly compare localized versus systemic effects of cholestasis and other retained bile components. pBDL can also be repurposed as a novel method to investigate mechanisms related to medications and cell migration.

Here, we present partial bile duct ligation as a surgical model of liver injury and regeneration in rodents.

小鼠部分胆管结扎术: 局部梗阻性胆汁淤积症的对照模型

In rodents, complete bile duct ligation (cBDL) of the common bile duct is an established surgical technique for studying obstructive cholestasis and bile ...

Methods Article

微探针：操作和使用的局部表面处理