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George Washington University

12 ARTICLES PUBLISHED IN JoVE

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Biology

Atmospheric-pressure Molecular Imaging of Biological Tissues and Biofilms by LAESI Mass Spectrometry
Peter Nemes 1, Akos Vertes 1
1Department of Chemistry, George Washington University

Laser ablation electrospray ionization (LAESI) is an atmospheric-pressure ion source for mass spectrometry. In the imaging mode, a mid-infrared laser probes the distributions of molecules across a tissue section or a biofilm. This technique presents a new approach for diverse bioanalytical studies carried out under native experimental conditions.

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Biology

Direct Analysis of Single Cells by Mass Spectrometry at Atmospheric Pressure
Bindesh Shrestha 1, Akos Vertes 1
1Department of Chemistry, George Washington University

Single cell analysis is performed by mass spectrometry on plant and animal cells at atmospheric pressure by using a sharpened optical fiber to sample the cells for laser ablation electrospray ionization (LAESI) mass spectrometry.

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Neuroscience

A Molecular Readout of Long-term Olfactory Adaptation in C. elegans
Chao He 1, Jin I. Lee 2, Noelle L'Etoile 3, Damien O'Halloran 1
1Department of Biological Sciences and Institute for Neuroscience, George Washington University, 2Fred Hutchinson Cancer Research Center, 3Department of Cell and Tissue Biology, University of California San Francisco

Here we describe a molecular readout of long-term olfactory adaptation in Caenorhabditis elegans. The Protein Kinase G, EGL-4, is necessary for stable adaptation responses in the primary sensory neuron pair called AWC. During prolonged odor exposure EGL-4 translocates from the cytosol to nucleus of the AWC.

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JoVE Journal

Blastomere Explants to Test for Cell Fate Commitment During Embryonic Development
Paaqua A. Grant 1, Mona B. Herold 1, Sally A. Moody 2
1Department of Biological Sciences, The George Washington University, 2Department of Anatomy and Regenerative Biology, The George Washington University

The fate of an individual embryonic cell can be influenced by inherited molecules and/or by signals from neighboring cells. Utilizing fate maps of the cleavage stage Xenopus embryo, single blastomeres can be identified for culture in isolation to assess the contributions of inherited molecules versus cell-cell interactions.

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Biology

A Practical Guide to Phylogenetics for Nonexperts
Damien O'Halloran 1
1Department of Biological Sciences and Institute for Neuroscience, The George Washington University

Here we describe a step-by-step pipeline for generating reliable phylogenies from nucleotide or amino acid sequence datasets. This guide aims to serve researchers or students new to phylogenetic analysis. 

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Biology

Imaging Cell Membrane Injury and Subcellular Processes Involved in Repair
Aurelia Defour *1, S. C. Sreetama *1, Jyoti K. Jaiswal 1,2
1Center for Genetic Medicine Research, Children's National Medical Center, 2Department of Integrative Systems Biology, George Washington University

The process of healing injured cells involves trafficking of specific proteins and subcellular compartments to the site of cell membrane injury. This protocol describes assays to monitor these processes.

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Bioengineering

Biofunctionalized Prussian Blue Nanoparticles for Multimodal Molecular Imaging Applications
Jennifer M. Vojtech 1,2, Juliana Cano-Mejia 1,2, Matthieu F. Dumont 1, Raymond W. Sze 1,3, Rohan Fernandes 1,3,4
1The Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Medical Center, 2Fischell Department of Bioengineering, University of Maryland, 3Department of Radiology, George Washington University, 4Department of Pediatrics, George Washington University

This protocol describes the synthesis of biofunctionalized Prussian blue nanoparticles and their use as multimodal, molecular imaging agents. The nanoparticles have a core-shell design where gadolinium or manganese ions within the nanoparticle core generate MRI contrast. The biofunctional shell contains fluorophores for fluorescence imaging and targeting ligands for molecular targeting.

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Chemistry

Microprobe Capillary Electrophoresis Mass Spectrometry for Single-cell Metabolomics in Live Frog (Xenopus laevis) Embryos
Rosemary M. Onjiko 1, Erika P. Portero 1, Sally A. Moody 2, Peter Nemes 1,3
1Department of Chemistry, George Washington University, 2Department of Anatomy & Regenerative Biology, George Washington University, 3Department of Chemistry & Biochemistry, University of Maryland, College Park

We describe steps that enable fast in situ sampling of a small portion of an individual cell with high precision and minimal invasion using capillary-based micro-sampling, to facilitate chemical characterization of a snapshot of metabolic activity in live embryos using a custom-built single cell capillary electrophoresis and mass spectrometry platform.

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Medicine

Optocardiography and Electrophysiology Studies of Ex Vivo Langendorff-perfused Hearts
Luther M. Swift 1,2, Rafael Jaimes III 1,2, Damon McCullough 1,2, Morgan Burke 1,2, Marissa Reilly 1,2, Takuya Maeda 1,2,3, Hanyu Zhang 4, Nobuyuki Ishibashi 1,2,3, Jack M. Rogers 4, Nikki Gillum Posnack 1,2,5
1Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, 2Children's National Heart Institute, Children's National Hospital, 3Center for Neuroscience Research, Children's National Hospital, 4Department of Biomedical Engineering, School of Engineering, University of Alabama at Birmingham, 5Department of Pediatrics, Department of Pharmacology & Physiology, School of Medicine and Health Sciences, George Washington University

The objective of this study was to establish a method for investigating cardiac dynamics using a translational animal model. The described experimental approach incorporates dual-emission optocardiography in conjunction with an electrophysiological study to assess electrical activity in an isolated, intact porcine heart model.

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Chemistry

Cell-Lineage Guided Mass Spectrometry Proteomics in the Developing (Frog) Embryo
Aparna B. Baxi 1,2, Leena R. Pade 1, Peter Nemes 1,2
1Department of Chemistry & Biochemistry, University of Maryland, 2Department of Anatomy & Cell Biology, The George Washington University

Here we describe a mass spectrometry-based proteomic characterization of cell lineages with known tissue fates in the vertebrate Xenopus laevis embryo.

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Medicine

Gastric Point of Care Ultrasound in Adults: Image Acquisition and Interpretation
Eric R. Heinz 1, Omar Al-Qudsi 2, David L. Convissar 3, Marianne D. David 1, Jennifer E. Dominguez 2, Stephen Haskins 4, Christina Jelly 5, Anahi Perlas 6, Anita N. Vincent 1, Yuriy S. Bronshteyn 2
1Department of Anesthesiology and Critical Care Medicine, George Washington University, 2Department of Anesthesiology, Duke University School of Medicine, Duke University Health System, 3Department of Anesthesiology, Massachusetts General Hospital, 4Department of Anesthesiology, Critical Care & Pain Management, Hospital for Special Surgery, 5Department of Anesthesiology, Vanderbilt University Medical Center, 6Department of Anesthesia and Pain Management, Toronto Western Hospital, University Health Network

This protocol introduces two methods for image acquisition in gastric ultrasonography. Additionally, tips are provided for interpreting this information to assist in medical decision-making.

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Medicine

Identifying Frailty Using Point-of-Care Ultrasonography: Image Acquisition and Assessment
Eric R. Heinz 1, Rachel Bernardo 2, Sarah Elizabeth Birk 3, William Manson 4, David B. MacLeod 5, Jeroen Molinger 5, Anita Vincent 1, Yuriy S. Bronshteyn 5
1Department of Anesthesiology and Critical Care Medicine, George Washington University, 2The George Washington University School of Medicine and Health Sciences Washington, 3Vanderbilt University Medical Center, 4Department of Anesthesiology, UVA Health, 5Department of Anesthesiology, Duke University School of Medicine, Duke University Health System

Here, we present a protocol to assess frailty in the perioperative setting using point-of-care ultrasound to measure quadriceps thickness. This method offers a practical, non-invasive alternative to traditional assessment methods, potentially enhancing perioperative care by quickly identifying frail patients.

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