1. Articles in category: Developmental Biology

    121-144 of 246 « 1 2 ... 3 4 5 6 7 8 9 10 11 »
    1. Silencing Of The Drosophila Ortholog Of SOX5 In Heart Leads To Cardiac Dysfunction As Detected By Optical Coherence Tomography

      Silencing Of The Drosophila Ortholog Of SOX5 In Heart Leads To Cardiac Dysfunction As Detected By Optical Coherence Tomography

      The SRY-related HMG-box 5 (SOX5) gene encodes a member of the SOX family of transcription factors. Recently, genome-wide association studies have implicated SOX5 as a candidate gene for susceptibility to four cardiac-related endophenotypes: higher resting heart rate (RHR), the electrocardiographic PR interval, atrial fibrillation (AF) and left ventricular mass (LVM). We have determined that human SOX5 has a highly conserved Drosophila ortholog, Sox102F, and have employed transgenic Drosophila models to quantitatively measure cardiac function in adult flies. For this purpose, we have developed a high-speed and ultrahigh-resolution optical coherence tomography (OCT) imaging system, which enables rapid cross-sectional imaging of the ...

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    2. Assessment and In Vivo Scoring of Murine Experimental Autoimmune Uveoretinitis Using Optical Coherence Tomography

      Assessment and In Vivo Scoring of Murine Experimental Autoimmune Uveoretinitis Using Optical Coherence Tomography

      Despite advances in clinical imaging and grading our understanding of retinal immune responses and their morphological correlates in experimental autoimmune uveoretinitis (EAU), has been hindered by the requirement for post-mortem histology. To date, monitoring changes occurring during EAU disease progression and evaluating the effect of therapeutic intervention in real time has not been possible. We wanted to establish whether optical coherence tomography (OCT) could detect intraretinal changes during inflammation and to determine its utility as a tool for accurate scoring of EAU. EAU was induced in C57BL/6J mice and animals evaluated after 15, 26, 36 and 60 days. At ...

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    3. Case Western Reserve University Receives NIH Grant for Investigating Optical Pacing of the Embryonic Heart

      Case Western Reserve University Receives NIH Grant for Investigating Optical Pacing of the Embryonic Heart

      Case Western Reserve University Received a 2013 NIH Grant for $176,625 for Investigating Optical Pacing of the Embryonic Heart. The principal investigator is Michael Jenkins. The program started in 2012 and ends in 2014. Below is a summary of the proposed work. Our long-term objective is to determine the influence biophysical forces have on heart development and how alterations of these forces early in development can lead to congenital heart defects (CHDs). CHDs are extremely prevalent affecting almost 36,000 newborns in the US each year, or 9 out of 1,000 live births. In order to tease apart ...

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    4. OCT guided microinjections for mouse embryonic research

      OCT guided microinjections for mouse embryonic research

      Optical coherence tomography (OCT) is gaining popularity as live imaging tool for embryonic research in animal models. Recently we have demonstrated that OCT can be used for live imaging of cultured early mouse embryos (E7.5-E10) as well as later stage mouse embryos in utero (E12.5 to the end of gestation). Targeted delivery of signaling molecules, drugs, and cells is a powerful approach to study normal and abnormal development, and image guidance is highly important for such manipulations. Here we demonstrate that OCT can be used to guide microinjections of gold nanoshell suspensions in live mouse embryos. This approach ...

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    5. In vivo functional imaging of embryonic chick heart using ultrafast 1310nm-band spectral domain optical coherence tomography

      In vivo functional imaging of embryonic chick heart using ultrafast 1310nm-band spectral domain optical coherence tomography

      During the cardiac development, the cardiac wall and the blood flow actively interact with each other, and determine the biomechanical environment to which the embryonic heart exposes. Employing an ultrafast 1310nm-band dual-camera spectral domain optical coherence tomography (SDOCT), the radial strain rate of the myocardial wall can be extracted with high signal-to-noise ratio, at the same time the Doppler velocity of the blood flow can also be displayed. The ability to simultaneously characterize these two cardiac tissues provides a powerful approach to better understand the interaction between the cardiac wall and the blood flow, which is important to the investigation ...

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    6. Changes in strain and blood flow in the outflow tract of chicken embryo hearts observed with spectral domain optical coherence tomography after outflow tract banding

      Changes in strain and blood flow in the outflow tract of chicken embryo hearts observed with spectral domain optical coherence tomography after outflow tract banding

      In this paper, we demonstrated the use of a spectral domain optical coherence tomography (OCT) in visualizing and quantifying changes in cardiac wall strain and blood-flow velocities under normal and altered hemodynamic conditions in chicken embryos at an early stage of development, focusing on the heart outflow tract (OFT). OCT imaging allowed in vivo evaluation strain and strain rate of the myocardium of the OFT through analyzing the periodic variation of the myocardial wall thickness. We found that alterations in hemodynamic conditions, through OFT banding, Changed strain and blood-flow velocities through the OFT as expected.

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    7. Critical Transitions in Early Embryonic Aortic Arch Patterning and Hemodynamics

      Critical Transitions in Early Embryonic Aortic Arch Patterning and Hemodynamics

      Transformation from the bilaterally symmetric embryonic aortic arches to the mature great vessels is a complex morphogenetic process, requiring both vasculogenic and angiogenic mechanisms. Early aortic arch development occurs simultaneously with rapid changes in pulsatile blood flow, ventricular function, and downstream impedance in both invertebrate and vertebrate species. These dynamic biomechanical environmental landscapes provide critical epigenetic cues for vascular growth and remodeling. In our previous work, we examined hemodynamic loading and aortic arch growth in the chick embryo at Hamburger-Hamilton stages 18 and 24. We provided the first quantitative correlation between wall shear stress (WSS) and aortic arch diameter in ...

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    8. A Spinal Cord Window Chamber Model for In Vivo Longitudinal Multimodal Optical and Acoustic Imaging in a Murine Model

      A Spinal Cord Window Chamber Model for In Vivo Longitudinal Multimodal Optical and Acoustic Imaging in a Murine Model

      In vivo and direct imaging of the murine spinal cord and its vasculature using multimodal (optical and acoustic) imaging techniques could significantly advance preclinical studies of the spinal cord. Such intrinsically high resolution and complementary imaging technologies could provide a powerful means of quantitatively monitoring changes in anatomy, structure, physiology and function of the living cord over time after traumatic injury, onset of disease, or therapeutic intervention. However, longitudinal in vivo imaging of the intact spinal cord in rodent models has been challenging, requiring repeated surgeries to expose the cord for imaging or sacrifice of animals at various time points ...

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    9. Semiautomatic and rapid quantification of heartbeat parameters in Drosophila using optical coherence tomography imaging

      Semiautomatic and rapid quantification of heartbeat parameters in Drosophila using optical coherence tomography imaging

      We report a semiautomatic algorithm that is specialized for rapid analysis of beat-to-beat contraction-relaxation parameters of the heart in Drosophila . The presented algorithm adapts the general graph theoretical image segmentation algorithm and a histogram-based thresholding algorithm, which can measure many cardiac parameters, including heart rate, heart period, diastolic and systolic intervals, and end-diastolic and end-systolic areas. Additionally, dynamic cardiac functions, such as arrhythmia index and percent fractional shortening, can be automatically calculated for all the recorded heartbeats over significant periods of time.

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    10. OCT News 2013 Student Paper Awarded to Jing-gao Zheng from Tsinghua University

      OCT News 2013 Student Paper Awarded to Jing-gao Zheng from Tsinghua University

      Jing-Gao Zheng from Tsinghua University was a winner of the 2013 OCT News Student Paper Award for his submission “Understanding early patterning and polarity of preimplantation mouse embryos with full-field optical coherence tomography.” Below is a summary of his work:  Morphogenetic relationship between early patterning and the polarity formation is of fundamental interest and remains controversial issues in mammalian preimplantation development. Label-free subcellular 3D live imaging technique is very helpful to its related studies. We have developed a novel system of full-field optical coherence tomography (FF-OCT) for non-invasive 3D sub-cellular live imaging of preimplantation mouse embryos with no need of ...

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    11. Understanding three-dimensional spatial relationship between the mouse second polar body and first cleavage plane with full-field optical coherence tomography

      Understanding three-dimensional spatial relationship between the mouse second polar body and first cleavage plane with full-field optical coherence tomography

      he morphogenetic relationship between early patterning and polarity formation is of fundamental interest and remains a controversial issue in preimplantation embryonic development. We use a label-free three-dimensional (3-D) imaging technique of full-field optical coherence tomography (FF-OCT) successfully for the first time to study the dynamics of developmental processes in mouse preimplantation lives. Label-free 3-D subcellular time-lapse images are demonstrated to investigate 3-D spatial relationship between the second polar body (2PB) and the first cleavage plane. By using FF-OCT together with quantitative study, we show that only 25% of the predicted first cleavage planes, defined by the apposing plane of two ...

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    12. 4D Reconstruction of the Beating Embryonic Heart From Two Orthogonal Sets of Parallel Optical Coherence Tomography Slice-Sequences

      4D Reconstruction of the Beating Embryonic Heart From Two Orthogonal Sets of Parallel Optical Coherence Tomography Slice-Sequences

      Current methods to build dynamic optical coherence tomography (OCT) volumes of the beating embryonic heart involve synchronization of 2D+time slice-sequences acquired over separate heartbeats. Temporal registration of these sequences is performed either through gating or post-processing. While synchronization algorithms that exclusively rely on image-intrinsic signals allow forgoing external gating hardware, they are prone to error accumulation, require operator-supervised correction, or lead to non-isotropic resolution. Here, we propose an imagebased, retrospective reconstruction technique that uses two sets of parallel 2D+T slice-sequences, acquired perpendicularly to each other, to yield accurate and automatic reconstructions with isotropic resolution. The method utilizes the ...

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    13. Oregon Health and Science University Receiveds NIH Grant f for 3-D Optical Imaging of The In Vivo Organ of Corti Motion at a Sub-Nanometer Scale

      Oregon Health and Science University Receiveds NIH Grant f for 3-D Optical Imaging of The In Vivo Organ of Corti Motion at a Sub-Nanometer Scale

      The Oregon Health and Science University Received a 2012 a NIH Grant for $310,929 for 3-D Optical Imaging of The In Vivo Organ of Corti Motion at a Sub-Nanometer Scale. The principal investigator is Alfred Nuttall. The program began in 2009 and ends in 2013. Below is a summary of the work. Low optical coherence tomography (OCT) has been used to image biological tissue and is the theoretical basis of microscopes that are commercially available to image the lens and cellular structures of the human eye. Interferometers based on OCT have not been produced but have unique properties useful ...

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    14. Optical coherence tomography provides an ability to assess mechanical property of cardiac wall of developing outflow tract in embryonic heart in vivo

      Optical coherence tomography provides an ability to assess mechanical property of cardiac wall of developing outflow tract in embryonic heart in vivo

      Knowledge of the biomechanical/elastic property of the cardiac wall is of fundamental importance in improving our understanding of cardiac development, particularly the interaction between the wall dynamics and hemodynamics in the developing outflow tract (OFT). We describe a method that employs optical coherence tomography (OCT) as a means to noninvasively measure the local elastic property of the cardiac wall in vivo . The method uses a time-lapse sequence of OCT images that represent the dynamic behavior of the OFT longitudinal section to calculate the regional wall pulse wave velocity (PWV), upon which the Young’s modulus of the cardiac wall ...

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    15. Noninvasive imaging of heart chamber in Drosophila with dual-beam optical coherence tomography

      Noninvasive imaging of heart chamber in Drosophila with dual-beam optical coherence tomography

      The heart chamber of an adult Drosophila is approximately 2 mm long and 0.5 mm wide, and the interwall separation of different heart portions during systole and diastole range from tens of micrometers to hundreds of micrometers. Furthermore, the heart chamber has a curved structure, which results in the larger differences in depth between the different heart portions. However, applying the wavelength calibration process before Fourier transform in an optical coherence tomography (OCT) system may cause degradation in system sensitivity and longitudinal resolution when the optical path difference between the reference and sample arms increases, which makes imaging the ...

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    16. Phenotyping of Mouse Models with OCT

      Phenotyping of Mouse Models with OCT

      Optical coherence tomography (OCT) is an invaluable technique to perform noninvasive retinal imaging in small animal models such as mice. It provides virtual cross sections that correlate well with histomorphometric data with the advantage that multiple iterative measurements can be acquired in time line analyses to detect dynamic changes and reduce the amount of animals needed per study.

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    17. 4D shear stress maps of the developing heart using Doppler optical coherence tomography

      4D shear stress maps of the developing heart using Doppler optical coherence tomography

      Accurate imaging and measurement of hemodynamic forces is vital for investigating how physical forces acting on the embryonic heart are transduced and influence developmental pathways. Of particular importance is blood flow-induced shear stress, which influences gene expression by endothelial cells and potentially leads to congenital heart defects through abnormal heart looping, septation, and valvulogenesis. However no imaging tool has been available to measure shear stress on the endocardium volumetrically and dynamically. Using 4D structural and Doppler OCT imaging, we are able to accurately measure the blood flow in the heart tube in vivo and to map endocardial shear stress throughout ...

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    18. First-ever 3-D Stress Map of Developing Embryonic Heart Sheds Light on Why Defects Form

      First-ever 3-D Stress Map of Developing Embryonic Heart Sheds Light on Why Defects Form

      Forces inside the beating heart of a human embryo help determine health of a baby’s heart: new 3-D images map these important forces As a human fetus develops, its heart has to keep pace with the new body’s ever-growing demands. Much of this is controlled by following genetic blueprints, but the embryonic heart also matures in response to the intense stresses of pumping blood. For the first time, researchers have been able to visualize in 3-D the stresses induced by flowing blood in an embryonic heart. The technique, which promises to provide new insight into how and why ...

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    19. Finding triggers of birth defects in an embryo heart

      Finding triggers of birth defects in an embryo heart

      Researchers at Case Western Reserve University have found a way to create three-dimensional maps of the stress that circulating blood places on the developing heart in an animal model – a key to understanding triggers of heart defects. The team has begun testing the technology to uncover how alcohol, drugs and other factors set off events that result in defects found in newborn humans. Passing blood cells drag on the endothelial cells that line the growing heart, a phenomenon called shear stress, which has been linked to changes in gene expression that results in defects, most often in the valves. But ...

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    20. Imaging Mouse Embryonic Cardiovascular Development

      Imaging Mouse Embryonic Cardiovascular Development

      arly development of the mammalian cardiovascular system is a highly dynamic process. Live imaging is an essential tool for analyzing normal and abnormal cardiovascular development and dynamics. This article describes two optical approaches for live dynamic imaging of mouse embryonic cardiovascular development: confocal microscopy and optical coherence tomography (OCT). Confocal microscopy, used in combination with fluorescent protein reporter lines, enables visualization of the developing and remodeling cardiovascular system with submicron resolution and even allows visualization of subcellular details of labeled structures. We describe mouse transgenic lines that can be used to image the developing vasculature and characterize hemodynamics by tracking ...

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    21. Extracting cardiac shapes and motion of the chick embryo heart outflow tract from four-dimensional optical coherence tomography images

      Extracting cardiac shapes and motion of the chick embryo heart outflow tract from four-dimensional optical coherence tomography images

      Recent advances in optical coherence tomography (OCT), and the development of image reconstruction algorithms, enabled four-dimensional (4-D) (three-dimensional imaging over time) imaging of the embryonic heart. To further analyze and quantify the dynamics of cardiac beating, segmentation procedures that can extract the shape of the heart and its motion are needed. Most previous studies analyzed cardiac image sequences using manually extracted shapes and measurements. However, this is time consuming and subject to inter-operator variability. Automated or semi-automated analyses of 4-D cardiac OCT images, although very desirable, are also extremely challenging. This work proposes a robust algorithm to semi automatically detect ...

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    22. Evaluation of zebrafish brain development using optical coherence tomography

      Evaluation of zebrafish brain development using optical coherence tomography

      The zebrafish is a well-established model system used to study and understand various human biological processes. The present study used OCT to investigate growth of the adult zebrafish brain. Twenty zebrafish were studied, using their standard lengths as indicators of their age. Zebrafish brain aging was evaluated by analyzing signal attenuation rates and texture features in regions of interest (ROIs). Optical scattering originates from light interaction with biological structures. During development, the zebrafish brain gains cells. Signal attenuation rate, therefore, increases with increasing zebrafish brain age. This study's analyses of texture features could not identify aging in zebrafish brain ...

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    23. In vivo functional imaging of blood flow and wall strain rate in outflow tract of embryonic chick heart using ultrafast spectral domain optical coherence tomography

      In vivo functional imaging of blood flow and wall strain rate in outflow tract of embryonic chick heart using ultrafast spectral domain optical coherence tomography

      During cardiac development, the cardiac wall and flowing blood are two important cardiac tissues that constantly interact with each other. This dynamic interaction defines appropriate biomechanical environment to which the embryonic heart is exposed. Quantitative assessment of the dynamic parameters of wall tissues and blood flow is required to further our understanding of cardiac development. We report the use of an ultrafast 1310-nm dual-camera spectral domain optical coherence tomography (SDOCT) system to characterize/image, in parallel, the dynamic radial strain rate of the myocardial wall and the Doppler velocity of the underlying flowing blood within an in vivo beating chick ...

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    24. Altering embryonic cardiac dynamics with optical pacing

      Altering embryonic cardiac dynamics with optical pacing

      Several studies have shown that altering blood flow early in development leads to congenital heart defects. In these studies the perturbations to hemodynamics were very gross manipulations (vessel ligation, conotruncal banding, etc.) that would be inappropriate for probing the delicate mechanisms responsible for mechanically-transduced signaling. Also, these perturbations lacked feedback from a monitoring system to determine the exact degree of alteration and the location of its effect. Here, we employed optical pacing (OP) to alter the heart rate in quail embryos and optical coherence tomography (OCT) to measure the resultant shear forces on the endocardium. OP is a new technique ...

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    121-144 of 246 « 1 2 ... 3 4 5 6 7 8 9 10 11 »
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