1. Articles in category: Developmental Biology

    121-144 of 237 « 1 2 3 4 5 6 7 8 9 10 »
    1. 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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    2. 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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    3. 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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    4. 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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    5. 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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    6. 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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    7. 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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    8. 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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    9. 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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    10. 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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    11. 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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    12. 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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    13. 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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    14. 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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    15. 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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    16. Two wavelength spectral domain optical coherence tomography systems for early stage chicken embryonic heart imaging

      Two wavelength spectral domain optical coherence tomography systems for early stage chicken embryonic heart imaging

      Blood Flow plays an important role during the early stage development of embryogenesis. Spectral domain optical coherence tomography (SDOCT), with high resolution and high acquisition speed, has been widely used in biological tissue imaging in recent years. By evaluation of phase difference between consecutive A-scan lines, SDOCT provides the ability for flow velocity measurement. In order to find the optimize SDOCT system for early stage chicken embryo heart outflow tract (OFT) flow measurement, two spectral domain optical coherence tomography setups were built in our lab with different central wavelength, i.e. 845nm and 1321nm. The performances of the two systems ...

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    17. A hybrid imaging system for simultaneous ophthalmic optical coherence tomography and dual-channel fluorescence detection in small animal models

      A hybrid imaging system for simultaneous ophthalmic optical coherence tomography and dual-channel fluorescence detection in small animal models

      We present a novel hybrid system that allows simultaneous high-resolution spectral domain optical coherence tomography (OCT) in the near-infrared and single-photon excited fluorescence (SPEF) detection in the green and red visible wavelength range for non-invasive multimodal imaging of the retina in small in vivo animal models such as zebrafish.

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    18. Biomechanics of the Chick Embryonic Heart Outflow Tract at HH18 Using 4D Optical Coherence Tomography Imaging and Computational Modeling

      Biomechanics of the Chick Embryonic Heart Outflow Tract at HH18 Using 4D Optical Coherence Tomography Imaging and Computational Modeling

      During developmental stages, biomechanical stimuli on cardiac cells modulate genetic programs, and deviations from normal stimuli can lead to cardiac defects. Therefore, it is important to characterize normal cardiac biomechanical stimuli during early developmental stages. Using the chicken embryo model of cardiac development, we focused on characterizing biomechanical stimuli on the Hamburger–Hamilton (HH) 18 chick cardiac outflow tract (OFT), the distal portion of the heart from which a large portion of defects observed in humans originate. To characterize biomechanical stimuli in the OFT, we used a combination of in vivo optical coherence tomography (OCT) imaging, physiological measurements and computational ...

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    19. Feature Of The Week 7/22/12: Label-Free Subcellular 3D Live Imaging of Preimplantation Mouse Embryos With Full-Field Optical Coherence Tomography

      Feature Of The Week 7/22/12: Label-Free Subcellular 3D Live Imaging of Preimplantation Mouse Embryos With Full-Field Optical Coherence Tomography

      arly patterning and polarity is of fundamental interest in preimplantation embryonic development. Label-free subcellular 3D live imaging is very helpful to its related studies. We have developed a novel system of full-field optical coherence tomography (FF-OCT) for noninvasive 3D subcellular live imaging of preimplantation mouse embryos with no need of dye labeling. 3D digitized embryos can be obtained by image processing. Label-free 3D live imaging is demonstrated for the mouse embryos at various typical preimplantation stages with a spatial resolution of 0.7 µm and imaging rate of 24 fps. Factors that relate to early patterning and polarity, such as ...

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    20. A more accurate and noninvasive look at cancerous tumors

      A more accurate and noninvasive look at cancerous tumors

      Lehigh University Press Release - Chao Zhou believes his work with combining imaging technologies has the potential to improve surgeries that remove malignant breast tumors. “As many as 40 percent of breast cancer patients now have to undergo a second surgery, because part of the tumor is left behind during the first,” says Zhou , an assistant professor of electrical and computer engineering. By combining two technologies—optical coherence tomography (OCT) and confocal microscopy—Zhou says doctors can more precisely pinpoint a tumor’s location and remove it entirely on the first try. One advantage of this hybrid approach, he says, is ...

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    21. Label-free subcellular 3D live imaging of preimplantation mouse embryos with full-field optical coherence tomography

      Label-free subcellular 3D live imaging of preimplantation mouse embryos with full-field optical coherence tomography

      Early patterning and polarity is of fundamental interest in preimplantation embryonic development. Label-free subcellular 3D live imaging is very helpful to its related studies. We have developed a novel system of full-field optical coherence tomography (FF-OCT) for noninvasive 3D subcellular live imaging of preimplantation mouse embryos with no need of dye labeling. 3D digitized embryos can be obtained by image processing. Label-free 3D live imaging is demonstrated for the mouse embryos at various typical preimplantation stages with a spatial resolution of 0.7 µm and imaging rate of 24 fps. Factors that relate to early patterning and polarity, such as ...

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    22. Case Western Reserve University Wins NIH Grant for Investigating the Early Embryonic Murine Heart Using Optical Coherence Tomography

      Case Western Reserve University Wins NIH Grant for Investigating the Early Embryonic Murine Heart Using Optical Coherence Tomography

      Case Western Reserve University received a 2012 NIH Grant for $712,087 for investigating the early embroyonic murine heart using optical coherence tomography. The project is part of a multiyear grant that began in 2009 and ends in 2013. The principle investigator is Andrew Rollins. Below is a summary of the proposed work.    The embryonic murine heart is a very important model of human heart development due to its four- chambered structure similar to the human heart, a short gestation period and a completely mapped genome which is easy to alter and manipulate. Lack of an appropriate imaging technology has ...

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    23. Practical approach for dispersion compensation in spectral-domain optical coherence tomography

      Practical approach for dispersion compensation in spectral-domain optical coherence tomography

      e proposed and demonstrated a digital method of dispersion compensation suitable for spectral-domain optical coherence tomography. The wavelength coordinate of the coherence spectrum was calibrated digitally using a two-order polynomial. A software-based scheme was introduced to determine the polynomial coefficients of the polynomial fitting spectrum wavelength. Therefore, the spectrum deformation introduced by dispersion can be compensated effectively. This method was experimentally validated by in vivo imaging an early-stage chick embryonic heart.

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      Mentions: Yi Wang
    24. Longitudinal Imaging of Heart Development With Optical Coherence Tomography

      Longitudinal Imaging of Heart Development With Optical Coherence Tomography

      Optical coherence tomography (OCT) has great potential for deciphering the role of mechanics in normal and abnormal heart development. OCT images tissue microstructure and blood flow deep into the tissue (1-2 mm) at high spatiotemporal resolutions allowing unprecedented images of the developing heart. Here, we review the advancement of OCT technology to image heart development and report some of our recent findings utilizing OCT imaging under environmental control for longitudinal imaging. Precise control of the environment is absolutely required in longitudinal studies that follow the growth of the embryo or studies comparing normal versus perturbed heart development to obtain meaningful ...

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    121-144 of 237 « 1 2 3 4 5 6 7 8 9 10 »
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