Featured Articles

  • A Single-Scan Inhomogeneity-Tolerant NMR Method

    A Single-Scan Inhomogeneity-Tolerant NMR Method for High-Resolution 2D J-Resolved Spectroscopy

    2D homonuclear J-resolved NMR spectroscopy has been widely applied to molecular conformational elucidation, metabolite analysis and in vivo study. However, conventional 2D J-resolved experiments generally suffer from two intrinsic issues, namely long acquisition duration and magnetic field inhomogeneity. Herein, a general single-scan NMR method, SGEN-J, is proposed to address aforementioned two crucial issues, thus applicable to rapidly detecting biological tissues with intrinsic susceptibility variations and abundant metabolites. Experiments of SGEN-J on various chemical and biological samples were performed to demonstrate its feasibility and effectiveness for molecular structure elucidation, biomedical study, even potential in vivo study.

  • Micro-coil design influences the spatial extent of responses to intracortical magnetic stimulation

    Micro-coil Design Influences the Spatial Extent of Responses to Intracortical Magnetic Stimulation

    Magnetic stimulation from micro-coils has the potential to improve the spatial resolution of cortical stimulation by selectively activating pyramidal neurons while avoiding passing axons. Here, we explored how micro-coil design influences the effectiveness and selectivity with which neurons are activated. Computational modeling and physiological experiments revealed that the use of a sharp bend at the coil tip (V-shaped) enhanced coil selectivity; an additional bend provided even higher selectivity. The use of a second loop enhanced coil strength. Our results suggest that further optimization of coil design may help to enhance both the strength and selectivity of future coil designs.

  • In vivo Visualization of Vasculature in Adult Zebrafish by High Frequency Ultrafast Ultrasound Imaging

    In vivo Visualization of Vasculature in Adult Zebrafish by using High-Frequency Ultrafast Ultrasound Imaging

    Zebrafish has recently become a crucial animal model for studying human diseases. However, when a zebrafish matures completely, its body loses transparency, making conventional optical imaging techniques difficult for visualizing the vessels. In the present study, high-frequency (40-MHz) micro-Doppler imaging (HFμDI) based on ultrafast ultrasound imaging was proposed for adult zebrafish dorsal vascular mapping in vivo. Blood flow signals were extracted using an eigen-based clutter filter. Blood vessels were clearly observed in 2D and 3D HFμDI. The minimal diameter of vessel can be detected was 36 μm. The maximum flow velocity range was approximately 3–4 mm/s on the dorsal vessels.

  • A Machine Learning Shock Decision Algorithm for use during Piston-driven Chest Compressions

    A Machine Learning Shock Decision Algorithm for use during Piston-driven Chest Compressions

    Cardiopulmonary resuscitation (CPR) therapy provides oxygen to the vital organs during cardiac arrest. An accurate heart rhythm analysis during piston-driven mechanical chest compressions would avoid interruptions in CPR therapy. We developed a rhythm analysis algorithm that combines adaptive filtering to remove compression artifacts from the electrocardiogram, multiresolution stationary wavelet transform (SWT) analysis for feature extraction, and a gaussian support vector machine (SVM) classifier for the shock/no-shock decision. Our results show that the heart rhythm can be accurately diagnosed during mechanical compressions, avoiding interruptions in CPR that compromise perfusion of the vital organs.

  • Adaptive and Wireless Recordings of Electrophysiological Signals during Concurrent Magnetic Resonance Imaging

    Adaptive and Wireless Recordings of Electrophysiological Signals during Concurrent Magnetic Resonance Imaging

    Strong electromagnetic fields during functional magnetic resonance imaging (fMRI) presents a challenging environment for concurrent electrophysiological recordings. Here, we present a miniaturized, wireless platform – “MR-Link”, that provides a hardware solution for simultaneous electrophysiological and fMRI signal acquisition. By detecting changes in the electromagnetic field during fMRI the device synchronizes amplification and sampling of biopotentials. Then, it wirelessly transmits the recorded data to the MR-receiver coil. MR-Link offers an inexpensive solution by eliminating the need for bulky amplifiers, high-speed sampling, additional storage or synchronization hardware. Thus, the technology is expected to open new avenues for widely accessible, integrative neuroimaging tools.

  • Wearable Devices for Precision Medicine and Health State Monitoring

    Wearable Devices for Precision Medicine and Health State Monitoring

    Wearable technologies will play an important role in advancing precision medicine by enabling measurement of clinically-relevant parameters that define an individual’s health state. The lifestyle and fitness markets have provided the driving force for the development of a broad range of wearable technologies that can be adapted for use in healthcare. Here we review existing technologies currently used for measurement of the four primary vital signs along with other clinically-relevant parameters. We review the relevant physiology that defines the measurement needs, and evaluate the different methods of signal transduction and measurement modalities for use in healthcare.

  • Patient-Specific Computational Simulations of Hyperpolarized 3He MRI Ventilation Defects in Healthy and Asthmatic Subjects

    Patient-Specific Computational Simulations of Hyperpolarized 3He MRI Ventilation Defects in Healthy and Asthmatic Subjects

    By combining medical imaging data (CT and MRI) with respiratory computer simulations, we create a powerful tool to correlate structure and function abnormalities in asthma subjects. Segmental volume defect percentages (SVDP) measured from hyperpolarized 3He MRI and CT images are used to define resistance-based boundary conditions for the gas flow models. Subjects with central airway remodeling had larger airway resistances, conducting airway pressure gradients, and secondary flow motion compared to the healthy subjects.

  • Optogenetic excitation of ipsilesional sensorimotor neurons is protective in acute ischemic stroke: a laser speckle imaging study

    Optogenetic Excitation of Ipsilesional Sensorimotor Neurons is Protective in Acute Ischemic Stroke: a Laser Speckle Imaging Study

    Specifically activating the sensorimotor neurons in acute stroke has been found to be protective. Laser speckle contrast imaging technique was used to quantify the neurovascular response to optogenetic stimulation within the first 24 hrs after stroke, in the aspect of cerebral blood flow changes. The results demonstrated that neuronal-specific excitation at acute stage could successfully compromise the expansion of the ischemic core and promote the neurovascular response after stroke. The results implied the neuron-specific modulation as a potential therapeutic intervention for the acute ischemic brain injury.

  • Epilepsy-on-a-chip System for Antiepileptic Drug Discovery

    Epilepsy-on-a-chip System for Antiepileptic Drug Discovery

    Hippocampal slice cultures spontaneously develop chronic epilepsy several days after dissection and are used as an in vitro model of post-traumatic epilepsy. This work describes the development of a hybrid microfluidic-microelectrode array device that improves the throughput of chronic recordings in hippocampal slice cultures and facilitates antiepileptic drug discovery. Our technology allows miniaturization of large and expensive multiple-slice electrophysiology systems to a single scalable chip. We used this epilepsy-on-a-chip device to carry out a screen of Receptor Tyrosine Kinases (RTKs) inhibitors and discovered two novel antiepileptic compounds. These ‘hits’ represent a promising first step in developing new antiepileptic drugs.

  • 3D Measurements of Acceleration-Induced Brain Deformation via Harmonic Phase Analysis and Finite-Element Models

    3D Measurements of Acceleration-Induced Brain Deformation via Harmonic Phase Analysis and Finite-Element Models

    Measuring brain deformation enables researchers to better understand traumatic brain injuries and develop methods for injury prevention. However, quantifying three-dimensional motion prevent in the intact human brain poses significant challenges. We present a new technique to estimate tissue deformation by combining data from tagged magnetic resonance images with a biomechanical model of the brain itself. This approach provides direct quantification of brain deformation from in vivo data during accelerative events that are typical of everyday activities, and provides insight into the brain’s behavior in more severe impacts.

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