JoVE Clinical and Translational Medicine
A New Single Chamber Implantable Defibrillator with Atrial Sensing: A Practical Demonstration of Sensing and Ease of Implantation
Heart Center Rostock, University Hospital of Rostock, Germany
Dual-chamber implantable cardioverter-defibrillators (ICDs) may improve detection of atrial fibrillation as well as differentiation of tachycardias. However, this advantage is undermined by complications associated with the second electrode, which is required in conventional dual chamber devices. Therefore, BIOTRONIK has developed a new electrode called the LinoxSMART S DX that, when used in conjunction with the Lumax DX ICD, offers dual-chamber detection without the risks associated with the second electrode.
JoVE Editorial
February 2012: This Month in JoVE
Here are some highlights from the February 2012 Issue of Journal of Visualized Experiments (JoVE).
JoVE Neuroscience
Recording Behavioral Responses to Reflection in Crayfish
Department of Biological Sciences, Brock University
We have developed two methods for studying effects of visual cues on behavior in the absence of tactile and chemical cues. One method involves videotaping responses of crayfish to reflective walls in an aquarium; the other examines effects of visual inputs provided by a live crayfish behind a transparent partition.
JoVE Neuroscience
Assessment of Social Interaction Behaviors
1Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 2Toronto Centre for Phenogenomics, Mount Sinai Hospital, 3Department of Medical Biophysics, University of Toronto, 4Department of Psychology, University of Toronto, 5Department of Psychiatry, University of Toronto
Here we describe a detailed protocol for examination of sociability in mice by using Crawley's sociability and preference for social novelty test. We describe the advantages and possible applications for this procedure, including critical details important for correct interpretation of the results.
JoVE Bioengineering
Time-lapse Fluorescence Imaging of Arabidopsis Root Growth with Rapid Manipulation of The Root Environment Using The RootChip
1Department of Plant Biology, Carnegie Institution for Science, 2Howard Hughes Medical Institute, 3Departments of Applied Physics and Bioengineering, Stanford University, 4Department of Microsystems Engineering (IMTEK) and Center for Biological Signaling Studies (BIOSS), University of Freiburg
This article provides a protocol for cultivation of Arabidopsis seedlings in the RootChip, a microfluidic imaging platform that combines automated control of growth conditions with microscopic root monitoring and FRET-based measurement of intracellular metabolite levels.
JoVE Clinical and Translational Medicine
Transplantation into the Anterior Chamber of the Eye for Longitudinal, Non-invasive In vivo Imaging with Single-cell Resolution in Real-time
1Diabetes Research Institute, University of Miami Miller School of Medicine, 2Department of Surgery, University of Miami Miller School of Medicine, 3Department of Medicine, University of Miami Miller School of Medicine, 4Department of Physiology & Biophysics, University of Miami Miller School of Medicine, 5The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet
A new approach combining intraocular transplantation and confocal microscopy enables longitudinal, non-invasive real-time imaging with single-cell resolution within grafted tissues in vivo. We demonstrate how to transplant pancreatic islets into the anterior chamber of the mouse eye.
JoVE General
Assessment of Mitochondrial Functions and Cell Viability in Renal Cells Overexpressing Protein Kinase C Isozymes
The effects of activation of protein kinase C (PKC) isozymes on mitochondrial functions associated with respiration and oxidative phosphorylation and on cell viability are described. The approach adapts adenoviral technique to selectively overexpress PKC isozymes in primary cell culture and a variety of assays to determine mitochondrial functions and energy status of the cell.
JoVE General
Fabrication and Use of MicroEnvironment microArrays (MEArrays)
1Life Science Division, Lawrence Berkeley National Laboratory, 2Department of Comparative Biochemistry, University of California, Berkeley
A combinatorial functional screening method for gaining insights into the impacts of the molecular composition of microenvironments on cellular functions is described. The method takes advantage of existing microarray-based technologies to generate arrays of defined combinatorial microenvironments that support cell adhesion and functional analysis.
JoVE Bioengineering
Impulsive Pressurization of Neuronal Cells for Traumatic Brain Injury Study
Department of Engineering Mechanics, University of Nebraska-Lincoln
A novel impulsive cell pressurization experiment has been developed using a Kolsky bar device to investigate the molecular/cellular mechanisms of blast-induced traumatic brain injury.
JoVE Neuroscience
A Galvanotaxis Assay for Analysis of Neural Precursor Cell Migration Kinetics in an Externally Applied Direct Current Electric Field
1Institute for Biomaterials and Biomedical Engineering, University of Toronto, 2Lyndhurst Centre, Toronto Rehabilitation Institute, 3Department of Surgery, University of Toronto
In this protocol we demonstrate how to construct custom chambers that permit the application of a direct current electric field to enable time-lapse imaging of adult brain derived neural precursor cell translocation during galvanotaxis.
JoVE General
Two Types of Assays for Detecting Frog Sperm Chemoattraction
1Department of Animal Sciences, University of Illinois, Urbana-Champaign, 2School of Life Sciences, Arizona State University
Eggs and the extracellular coatings around eggs frequently release peptides, proteins and small molecules that communicate with sperm to guide them to the egg thereby promoting fertilization. Using frog sperm we describe and compare two classes of assays used to detect sperm chemoattraction – sperm accumulation assays and sperm tracking assays.
JoVE Clinical and Translational Medicine
An In Vitro System to Study Tumor Dormancy and the Switch to Metastatic Growth
1Department of Biology, University of Haifa, 2Transgenic Oncogenesis and Genomics Section, Laboratory of Cancer Biology and Genetics, National Cancer Institute
A modified 3-D in vitro system is presented in which growth characteristics of several tumor cell lines in reconstituted basement membrane correlate with the dormant or proliferative behavior of the tumor cells at a metastatic secondary site in vivo.
JoVE Bioengineering
Electric Field-controlled Directed Migration of Neural Progenitor Cells in 2D and 3D Environments
1School of Dentistry, Cardiff Institute of Tissue Engineering & Repair, Cardiff University, 2Shandong Qianfoshan Hospital, Shandong University School of Medicine, 3Dermatology and Ophthalmology Research, Institute for Regenerative Cures, University of California at Davis
This protocol demonstrates methods used to establish 2D and 3D environments in custom-designed electrotactic chambers, which can track cells in vivo/ex vivo using time-lapse recording at the single cell level, in order to investigate galvanotaxis/electrotaxis and other cellular responses to direct current (DC) electric fields (EFs).
JoVE Bioengineering
Microfluidic Chip Fabrication and Method to Detect Influenza
1Department of Mechanical Engineering, Boston University, 2Department of Biomedical Engineering, Boston University
An integrated microfluidic thermoplastic chip has been developed for use as a molecular diagnostic. The chip performs nucleic acid extraction, reverse transcriptase, and PCR. Methods for fabricating and running the chip are described.
JoVE General
Live Imaging of GFP-labeled Proteins in Drosophila Oocytes
Department of Biology, Vassar College
A protocol for live imaging of GFP-tagged proteins or autofluorescent structures in individual Drosophila oocytes is described.
JoVE Bioengineering
Parallel-plate Flow Chamber and Continuous Flow Circuit to Evaluate Endothelial Progenitor Cells under Laminar Flow Shear Stress
1Department of Surgery, Duke University Medical Center, 2Department of Biomedical Engineering, Duke University, 3School of Medicine, University of Pennsylvania, 4Department of Medicine, Division of Cardiology, Duke University Medical Center
We are describing a method to subject adherent cells to laminar flow shear stress in a sterile continuous flow circuit. The cells' adhesion, morphology can be studied through the transparent chamber, samples obtained from the circuit for metabolite analysis and cells harvested after shear exposure for future experiments or culture.
JoVE Bioengineering
Microfluidic Device for Recreating a Tumor Microenvironment in Vitro
Department of Chemical Engineering, University Of Massachusetts Amherst
We present the procedure for fabrication and operation of a microfluidic device that recreates heterogeneous tumor microenvironments in vitro. The variability in apoptosis within tumor tissue was quantified using fluorescent stains and the effective diffusion coefficient of the chemotherapeutic drug doxorubicin into tumor tissue was evaluated.
JoVE General
Microfluidic Chips Controlled with Elastomeric Microvalve Arrays
Dept. of Bioengineering, University of Washington
We demonstrate protocols for manufacturing and automating elastomeric polydimethylsiloxane (PDMS)-based microvalve arrays that need no extra energy to close and feature photolithographically defined precise volumes. A parallel subnanoliter-volume mixer and an integrated microfluidic perfusion system are presented.
JoVE Neuroscience
A Fully Automated and Highly Versatile System for Testing Multi-cognitive Functions and Recording Neuronal Activities in Rodents
The Neurosciences Institute, San Diego, CA
In this report, we present a fully automated and highly versatile system capable of simultaneously testing multi-cognitive behaviors and recording neuronal activities for rodents.
JoVE General
The Preparation of Drosophila Embryos for Live-Imaging Using the Hanging Drop Protocol
Department of Biology, University of Waterloo
A simple, inexpensive, and effective method of preparing Drosophila embryos for live-imaging analysis is presented. Our protocol provides humidity and gas exchange and does not compress the Drosophila embryo. This method is suitable for GFP-based live imaging of Drosophila embryos using a stereomicroscope or upright compound microscope.
JoVE General
Imaging G-protein Coupled Receptor (GPCR)-mediated Signaling Events that Control Chemotaxis of Dictyostelium Discoideum
Here, we describe detailed live cell imaging methods for investigating chemotaxis. We present fluorescence microscopic methods to monitor spatiotemporal dynamics of signaling events in migrating cells. Measurement of signaling events permits us to further understand how a GPCR-signaling network achieves gradient sensing of chemoattractants and controls directional migration of eukaryotic cells.
JoVE General
Single-molecule Imaging of Gene Regulation In vivo Using Cotranslational Activation by Cleavage (CoTrAC)
1Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, 2Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 3Department of Physics, Jilin University
We describe a fluorescence microscopy method, Co-Translational Activation by Cleavage (CoTrAC), to image the production of protein molecules in live cells with single-molecule precision without perturbing the protein's functionality. This method has been used to follow the stochastic expression dynamics of a transcription factor, the λ repressor CI 1.
JoVE Neuroscience
Targeted Labeling of Neurons in a Specific Functional Micro-domain of the Neocortex by Combining Intrinsic Signal and Two-photon Imaging
Department of Neuroscience, Medical University of South Carolina
A method is described for labeling neurons with fluorescent dyes in predetermined functional micro-domains of the neocortex. First, intrinsic signal optical imaging is used to obtain a functional map. Then two-photon microscopy is used to label and image neurons within a micro-domain of the map.
JoVE Neuroscience
In vivo Neuronal Calcium Imaging in C. elegans
1Department of Physiology and Biophysics, Boston University School of Medicine, 2Boston University Photonics Center
With its small transparent body, well-documented neuroanatomy and a host of amenable genetic techniques and reagents, C. elegans makes an ideal model organism for in vivo neuronal imaging using relatively simple, low-cost techniques. Here we describe single neuron imaging within intact adult animals using genetically encoded fluorescent calcium indicators.
JoVE General
Visualizing Single-molecule DNA Replication with Fluorescence Microscopy
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School
This protocol demonstrates a simple single-molecule fluorescence microscopy technique for visualizing DNA replication by individual replisomes in real time.
JoVE Neuroscience
Electrophysiology of Scorpion Peg Sensilla
Department of Zoology, University of Oklahoma
This article describes an electrophysiological method for isolating chemical stimulation to individual sensilla via extracellular, tip-recordings under mineral oil.
JoVE Clinical and Translational Medicine
Evaluation of Cancer Stem Cell Migration Using Compartmentalizing Microfluidic Devices and Live Cell Imaging
1Department of Biomedical Engineering, University of Wisconsin-Madison, 2Materials Science Program, University of Wisconsin-Madison, 3Department of Neurological Surgery, University of Wisconsin-Madison, 4Carbone Comprehensive Cancer Center and Center for Stem Cell and Regenerative Medicine, University of Wisconsin-Madison
A compartmentalizing microfluidic device for investigating cancer stem cell migration is described. This novel platform creates a viable cellular microenvironment and enables microscopic visualization of live cell locomotion. Highly motile cancer cells are isolated to study molecular mechanisms of aggressive infiltration, potentially leading to more effective future therapies.
JoVE General
Measurement of Cellular Chemotaxis with ECIS/Taxis
1Molecular and Cell Biology, University of Connecticut, 2University of Connecticut
The ECIS/Taxis system is an automated, real-time assay that measures cellular chemotaxis. In this assay, cells move beneath a layer of agarose to arrive at a target electrode. Cellular movement is measured by the onset of resistance to AC current 0.
JoVE General
Using the GELFREE 8100 Fractionation System for Molecular Weight-Based Fractionation with Liquid Phase Recovery
Research and Development, Protein Discovery, Inc.
The accompanying video describes the use of the GELFREE 8100 Fractionation System, which partitions complex protein samples on the basis of molecular weight and recovers the fractions in liquid phase. The video describes how the technology works, how it is used, and provides resultant data, with polyacrylamide gel electrophoresis analysis of fractionated bovine liver homogenate.
JoVE Neuroscience
Imaging Analysis of Neuron to Glia Interaction in Microfluidic Culture Platform (MCP)-based Neuronal Axon and Glia Co-culture System
1Department of Neuroscience, Tufts University, 2Neuroscience Program, Tufts Sackler School of Graduate Biomedical Sciences
This study describes the procedures of setting up a novel neuronal axon and (astro)glia co-culture platform. In this co-culture system, manipulation of direct interaction between a single axon (and single glial cell) becomes feasible, allowing mechanistic analysis of the mutual neuron to glial signaling.
JoVE General
Two-photon axotomy and time-lapse confocal imaging in live zebrafish embryos
1Department of Molecular Cell and Developmental Biology, University of California, Los Angeles, 2Departments of Neurology and Neurobiology, University of California, Los Angeles
Here we describe a method for mounting zebrafish embryos for long-term imaging, two-photon imaging and tissue-damage techniques, and time-lapse confocal imaging.
JoVE Immunology and Infection
Pseudomonas aeruginosa and Saccharomyces cerevisiae Biofilm in Flow Cells
1Department of Systems Biology, Danish Technical University, 2Department of Biology, University of Copenhagen
Protocol describing the application of a flow cell system for growing and analyzing microbial biofilms for Confocal Laser Scanning Microscopy (CLSM).
JoVE Bioengineering
High-throughput Protein Expression Generator Using a Microfluidic Platform
We present a microfluidic approach for the expression of protein arrays. The device consists of thousands of reaction chambers controlled by micro-mechanical valves. The microfluidic device is mated to a microarray-printed gene library. These genes are then transcribed and translated on-chip, resulting in a protein array ready for experimental use.
JoVE Immunology and Infection
Isolation of Human Umbilical Vein Endothelial Cells and Their Use in the Study of Neutrophil Transmigration Under Flow Conditions
Department of Physiology and Pharmacology, University of Calgary
This article first describes a procedure for isolating human endothelial cells from umbilical veins and then shows how to use these cells to examine neutrophil transmigration under flow conditions. By using a low-volume flow chamber made from a polymer with the optical characteristics of glass, live-cell fluorescent imaging of rare cell populations is also possible.
JoVE General
High-Resolution Video Tracking of Locomotion in Adult Drosophila Melanogaster
The study of complex locomotor behavior in Drosophila melanogaster is dependent upon the ability to quantify changes in a given fly's movement. This article demonstrates how to do this using a high-resolution tracking system.
JoVE Bioengineering
Monitoring Protein Adsorption with Solid-state Nanopores
Department of Physics, Syracuse University
A method of using solid-state nanopores to monitor the non-specific adsorption of proteins onto an inorganic surface is described. The method employs the resistive-pulse principle, allowing for the adsorption to be probed in real-time and at the single-molecule level. Because the process of single protein adsorption is far from equilibrium, we propose the employment of parallel arrays of synthetic nanopores, enabling for the quantitative determination of the apparent first-order reaction rate constant of protein adsorption as well as and the Langmuir adsorption constant.
JoVE Neuroscience
An In Vitro Preparation for Eliciting and Recording Feeding Motor Programs with Physiological Movements in Aplysia californica
1Department of Biology, Case Western Reserve University, 2Department of Neurosciences, Case Western Reserve University, 3Department of Biomedical Engineering, Case Western Reserve University
We describe a technique to extracellularly record and stimulate from nerves, muscles, and individual identified neurons in vitro while eliciting and observing different types of feeding behaviors in the feeding apparatus of Aplysia.
JoVE Immunology and Infection
Live Cell Imaging of Bacillus subtilis and Streptococcus pneumoniae using Automated Time-lapse Microscopy
This protocol provides a step-by-step procedure to monitor single cell behavior of different bacteria in time using automated fluorescence time-lapse microscopy. Furthermore, we provide guidelines how to analyze the microscopy images.
JoVE Applied Physics
Angle-resolved Photoemission Spectroscopy At Ultra-low Temperatures
1Institute for Solid State Research, IFW-Dresden, 2Institute of Metal Physics of National Academy of Sciences of Ukraine, 3Diamond Light Source LTD, 4Department of Physics, University of Johannesburg, 5CNR-SPIN, and Dipartimento di Fisica "E. R. Caianiello", Università di Salerno, 6Institute of Physics of Complex Matter, École Polytechnique Fédérale de Lausanne
The overall goal of this method is to determine the low-energy electronic structure of solids at ultra-low temperatures using Angle-Resolved Photoemission Spectroscopy with synchrotron radiation.
JoVE Applied Physics
Optical Trapping of Nanoparticles
Electrical and Computer Engineering, University of Victoria
The following setup approach details low power optical trapping of dielectric nanoparticles using a double-nanohole in metal film.
JoVE General
Rapid Genetic Analysis of Epithelial-Mesenchymal Signaling During Hair Regeneration
Program in Epithelial Biology, Stanford University School of Medicine
Tissue-specific analysis of a hair follicle regeneration model using lentivirus to mediate gain- or loss-of-function.
JoVE Neuroscience
Assaying Locomotor, Learning, and Memory Deficits in Drosophila Models of Neurodegeneration
Department of Molecular and Cellular Pharmacology, University of Miami, Miller School of Medicine
Behavior assays for measuring locomotor functions, learning, and memory abilities in Drosophila.
JoVE Bioengineering
Quantifying the Mechanical Properties of the Endothelial Glycocalyx with Atomic Force Microscopy
Department of Biomedical Engineering, University of Rochester
The mechanical characteristics of endothelial glycocalyx were measured by indentation using micron sized spheres on AFM cantilevers. Endothelial cells were cultured in a custom chamber under physiological flow conditions to induce glycocalyx expression. Data were analyzed using a thin film model to determine the glycocalyx thickness and modulus.
JoVE Bioengineering
Creating Adhesive and Soluble Gradients for Imaging Cell Migration with Fluorescence Microscopy
1Centre for Vascular Research and Australian Centre for Nanomedicine, The University of New South Wales, 2School of Chemistry and Australian Centre for Nanomedicine, The University of New South Wales
A method for the assembly of adhesive and soluble gradients in a microscopy chamber for live cell migration studies is described. The engineered environment combines antifouling surfaces and adhesive tracks with solution gradients and therefore allows one to determine the relative importance of guidance cues.
JoVE General
Preparation of Artificial Bilayers for Electrophysiology Experiments
Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University
Planar lipid bilayers, also called artificial lipid bilayers, allow you to study ion-conducting channels in a well-defined environment. Here, we demonstrate the individual steps needed to prepare the bilayer chamber, the electrodes and how to test that the bilayer is suitable for single-channel measurements.
JoVE General
Antifouling Self-assembled Monolayers on Microelectrodes for Patterning Biomolecules
1Department of Physics, Texas A&M University (TAMU), 2Department of Biomedical Engineering, Texas A&M University (TAMU)
We present a procedure for forming a poly(ethylene glycol) self-assembled monolayer (PEG-SAM) on a silicon substrate with gold microelectrodes. The PEG-SAM is formed in a single step and prevents biofouling on silicon and gold surfaces. Electrophoresis is then used for patterning biomolecules down to the nanoscale.
JoVE General
Primary Cell Cultures from Drosophila Gastrula Embryos
1Department of Genetics, Harvard Medical School, 2 , Howard Hughes Medical Institute
We provide a detailed protocol for preparing primary cells dissociated from Drosophila embryos. The ability to carry out the effective RNAi perturbation, together with other molecular, biochemical and cell imaging methods will allow a variety of questions to be addressed in Drosophila primary cells.
JoVE Applied Physics
Fabrication And Characterization Of Photonic Crystal Slow Light Waveguides And Cavities
School of Physics & Astronomy, University of St Andrews
Use of photonic crystal slow light waveguides and cavities has been widely adopted by the photonics community in many differing applications. Therefore fabrication and characterization of these devices are of great interest. This paper outlines our fabrication technique and two optical characterization methods, namely: interferometric (waveguides) and resonant scattering (cavities).
JoVE General
Use of Time Lapse Microscopy to Visualize Anoxia-induced Suspended Animation in C. elegans Embryos
Department of Biological Sciences, University of North Texas
Described here is an in vivo technique to image sub-cellular structures in animals exposed to anoxia using a gas flow through microincubation chamber in conjunction with a spinning disc confocal microscope. This method is straightforward and flexible enough to suit a variety of experimental parameters and model systems.
JoVE General
Blood Collection from the American Horseshoe Crab, Limulus Polyphemus
1Department of Molecular and Cell Biology, University of California, Davis, 2Marine Biological Laboratory - MBL- woods hole, 3Department of Biological Sciences, Hunter College of CUNY
The American horseshoe crab, Limulus polyphemus, is arguably the most convenient source for large quantities of blood of any invertebrate. The blood is simple in composition, with only one cell-type in the general circulation, the granular amebocyte, and only three abundant proteins in the plasma, hemocyanin, the C-reactive proteins, and α2-macroglobulin. Blood is collected from the heart and the blood cells and plasma are separated by centrifugation.
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