1. Articles in category: Developmental Biology

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    1. Hemodynamic Flow Visualization of Early Embryonic Great Vessels Using μPIV

      Hemodynamic Flow Visualization of Early Embryonic Great Vessels Using μPIV

      Microparticle image velocimetry (μPIV) is an evolving quantitative methodology to closely and accurately monitor the cardiac flow dynamics and mechanotransduction during vascular morphogenesis. While PIV technique has a long history, contemporary developments in advanced microscopy have significantly expanded its power. This chapter includes three new methods for μPIV acquisition in selected embryonic structures achieved through advanced optical imaging: (1) high-speed confocal scanning of transgenic zebrafish embryos, where the transgenic erythrocytes act as the tracing particles; (2) microinjection of artificial seeding particles in chick embryos visualized with stereomicroscopy; and (3) real-time, time-resolved optical coherence tomography acquisition of vitelline vessel flow profiles ...

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    2. Retinal Regeneration Following OCT-guided Laser Injury in Zebrafish

      Retinal Regeneration Following OCT-guided Laser Injury in Zebrafish

      Purpose: Establish a focal injury/regeneration model in zebrafish using laser photocoagulation guided by optical coherence tomography (OCT). Methods: Adult zebrafish were imaged by OCT and confocal scanning laser ophthalmoscopy (cSLO) in room air through a contact lens. Using a beam combiner, 532nm laser photocoagulation was applied using the OCT C-scan image for targeting. Laser spots of 42-47mW were delivered to the retina. At multiple intervals post-injury, fish were imaged using both OCT and cSLO to follow the progression of each lesion. Histologic sections and TUNEL staining were performed to monitor the injury response. Results: Round lesions (26057 ± 621μm2 ...

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    3. Blood flow dynamics reflect degree of outflow tract banding in Hamburger-Hamilton stage 18 chicken embryos

      Blood flow dynamics reflect degree of outflow tract banding in Hamburger-Hamilton stage 18 chicken embryos

      Altered blood flow during embryonic development has been shown to cause cardiac defects; however, the mechanisms by which the resulting haemodynamic forces trigger heart malformation are unclear. This study used heart outflow tract banding to alter normal haemodynamics in a chick embryo model at HH18 and characterized the immediate blood flow response versus the degree of band tightness. Optical coherence tomography was used to acquire two-dimensional longitudinal structure and Doppler velocity images from control ( n = 16) and banded ( n = 25, 6–64% measured band tightness) embryos, from which structural and velocity data were extracted to estimate haemodynamic measures. Peak blood ...

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    4. Dual modality optical coherence and whole-body photoacoustic tomography imaging of chick embryos in multiple development stages

      Dual modality optical coherence and whole-body photoacoustic tomography imaging of chick embryos in multiple development stages

      Chick embryos are an important animal model for biomedical studies. The visualization of chick embryos, however, is limited mostly to postmortem sectional imaging methods. In this work, we present a dual modality optical imaging system that combines swept-source optical coherence tomography and whole-body photoacoustic tomography, and apply it to image chick embryos at three different development stages. The explanted chick embryos were imaged in toto with complementary contrast from both optical scattering and optical absorption. The results serve as a prelude to the use of the dual modality system in longitudinal whole-body monitoring of chick embryos in ovo .

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    5. Gated optical coherence tomography (OCT)

      Gated optical coherence tomography (OCT)

      Systems, methods, and other embodiments associated with gated optical coherence tomography (OCT) are described. One example method includes generating an image control signal to control an OCT apparatus to acquire an image of an embryonic heart at a specified point in time during a cardiac cycle of the embryonic heart. The method may also include controlling the OCT apparatus to acquire the image based on the image control signal. In different examples, the image may be acquired in vivo or from an excised heart that is paced. The OCT apparatus and the embryonic heart may be housed in an environmental ...

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    6. Optical Coherence Tomography: Age estimation of Calliphora vicina pupae in vivo?

      Optical Coherence Tomography: Age estimation of Calliphora vicina pupae in vivo?

      Necrophagous blowfly pupae are valuable contributors to the estimation of post-mortem interval, should an accurate age estimate be obtained. At present, this is reliant on a combination of rearing and destructive methods conducted on preserved samples, including morphological observation and gene expression analyses. This study demonstrates the use of optical coherence tomography (OCT) as a tool for in vivo morphological observation and pupal age estimation. Using a Michelson OCT microscope, alive and preserved four and ten-day old Calliphora vicina pupae were scanned in different orientations. Two and three-dimensional images were created. Morphological characteristics such as the brain, mouthparts and legs ...

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    7. Zebrafish as a Model to Study Emmetropization, Refractive Error, and Retinal Substructure using Spectral Domain-Optical Coherence Tomography

      Zebrafish as a Model to Study Emmetropization, Refractive Error, and Retinal Substructure using Spectral Domain-Optical Coherence Tomography

      Purpose : Spectral-domain optical coherence tomography (SD-OCT) accurately measures the anatomy and dimensions of the eye in vivo . Here, we characterize emmetropization of wild-type zebrafish, myopia onset in bugeye/lrp2 mutants, and visualize the highly ordered cone photoreceptor mosaic by SD-OCT. We combine high resolution visualization with an animal model amenable to genetic manipulation that can be used to study candidate genes for refractive error and other ocular diseases. Methods : Eye axial length, focal length and lens diameter were measured in wild-type and bugeye/lrp2 mutant zebrafish throughout their lifespan using a Bioptigen SD-OCT system. Cone photoreceptor mosaics were visualized using ...

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    8. Baylor College of Medicine Receives NIH Grant for Studying Biomechanics of Early Mammalian Cardiogenesis

      Baylor College of Medicine Receives NIH Grant for Studying Biomechanics of Early Mammalian Cardiogenesis

      Baylor College of Medicine Received a 2014 NIH Grant for $378,647 for Biomechanics of Early Mammalian Cardiogenesis. The principal investigator is Irina Larina. The program began in 2013 and ends in 2018. Below is a summary of the proposed work. Congenital heart defects are among the most common birth defects and the leading cause of death in children born with congenital defects. Understanding how the early embryonic heart functions and what regulatory mechanisms are involved in early cardiogenesis is highly important for advancement of heart defects research. Biomechanical stimuli, including blood flow and heart contraction, are important regulators of ...

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    9. Three-dimensional correction of conduction velocity in the embryonic heart using integrated optical mapping and optical coherence tomography

      Three-dimensional correction of conduction velocity in the embryonic heart using integrated optical mapping and optical coherence tomography

      Optical mapping (OM) of cardiac electrical activity conventionally collects information from a three-dimensional (3-D) surface as a two-dimensional (2-D) projection map. When applied to measurements of the embryonic heart, this method ignores the substantial and complex curvature of the heart surface, resulting in significant errors when calculating conduction velocity, an important electrophysiological parameter. Optical coherence tomography (OCT) is capable of imaging the 3-D structure of the embryonic heart and accurately characterizing the surface topology. We demonstrate an integrated OCT/OM imaging system capable of simultaneous conduction mapping and 3-D structural imaging. From these multimodal data, we obtained 3-D activation maps ...

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    10. Case Western Reserve University Receives NIH Grant for Integrated Imaging of the Form and Function of the Beating Embryonic Heart

      Case Western Reserve University Receives NIH Grant for Integrated Imaging of the Form and Function of the Beating Embryonic Heart

      Case Western Reserve University receives a 2014 NIH grant for $373,641 for Integrated Imaging of the Form and Function of the Beating Embryonic Heart. The principal investigator is Andrew Rollins. The program began in 2006 and ends in 2017. Below is a summary of the prposed work. Congenital heart defects (CHDs) afflict 36,000 babies born in the US each year and survivors often require several surgical interventions in their shortened lifetime. Despite continuous efforts, the mechanisms leading to CHDs remain largely unclear. In part, this is because most developmental cardiology studies fail to address the influential role of ...

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    11. Washington University Receives NIH Grant for Studying Mechanics of Early Brain and Eye Development

      Washington University Receives NIH Grant for Studying Mechanics of Early Brain and Eye Development

      Washington University Receives a 2014 NIH Grant for $332,591 for Studying Mechanics of Early Brain and Eye Development. The principle investigator is Larry Taber. The program beganin 2010 and ends in 2015. Below is a summary of the proposed work. In human embryos, the primary subdivisions of the brain (forebrain, midbrain, and hindbrain) are formed by the fourth week of gestation. During this time, the primitive eyes (optic vesicles) emerge as protrusions from the forebrain. The forms of these organs are highly conserved. Abnormalities in size and shape of the early brain are known to cause serious neurological disorders ...

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    12. Oregon Health & Science University Receives NIH grant to study Dynamic Changes in the Chick Developing Heard in Response to Altered Hemodyanmics

      Oregon Health & Science University Receives NIH grant to study Dynamic Changes in the Chick Developing Heard in Response to Altered Hemodyanmics

      Oregon Health & Science University received at 2014 NIH grant for $404,161 to study Dynamic Changes in the Chick Developing Heard in Response to Altered Hemodyanmics. The principal investigator is Sandra Rugonyi. The program began in 2008 and ends in 2015. Below is a summary of the proposed work. About 1% newborn babies have congenital heart disease (CHD), the leading cause of death among children. The majority of CHD cases are believed not to have a genetic cause. Other factors, such as abnormal blood flow during embryonic and fetal stages can lead to heart malformations and thus CHD through poorly ...

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    13. Microvascular anastomosis in rodent model evaluated by Fourier domain Doppler optical coherence tomography

      Microvascular anastomosis in rodent model evaluated by Fourier domain Doppler optical coherence tomography

      Vascular and microvascular anastomosis are critical components of reconstructive microsurgery, vascular surgery and transplant surgery. Imaging modality that provides immediate, real-time in-depth view and 3D structure and flow information of the surgical site can be a great valuable tool for the surgeon to evaluate surgical outcome following both conventional and innovative anastomosis techniques, thus potentially increase the surgical success rate. Microvascular anastomosis for vessels with outer diameter smaller than 1.0 mm is extremely challenging and effective evaluation of the outcome is very difficult if not impossible using computed tomography (CT) angiograms, magnetic resonance (MR) angiograms and ultrasound Doppler. Optical ...

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    14. Towards a comprehensive eye model for zebrafish retinal imaging using full range spectral domain optical coherence tomography

      Towards a comprehensive eye model for zebrafish retinal imaging using full range spectral domain optical coherence tomography

      In regenerative medicine, the zebrafish is a prominent animal model for studying degeneration and regeneration processes, e.g. of photoreceptor cells in the retina. By means of optical coherence tomography (OCT), these studies can be conducted over weeks using the same individual and hence reducing the variability of the results. To allow an improvement of zebrafish retinal OCT imaging by suitable optics, we developed a zebrafish eye model using geometrical data obtained by in vivo dispersion encoded full range OCT as well as a dispersion comprising gradient index (GRIN) lens model based on refractive index data found in the literature ...

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    15. Rotational imaging OCT for full-body embryonic imaging

      Rotational imaging OCT for full-body embryonic imaging

      Optical coherence tomography (OCT) has proved to be an effective tool to study the development of mammalian embryos due to its high resolution and contrast. However, light attenuation is an important factor which constrains the imaging depth of OCT. Limitation of imaging depth will inhibit us to better study the structural characteristics of mouse embryos. Here we propose a new method, rotational imaging OCT (riOCT), to improve the imaging depth and provide full-body embryonic imaging. The experimental setup comprises the swept source OCT system and the square glass tube mounted on a rotational stage. The E10.5 mouse embryos are ...

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    16. Optical tissue clearing improves usability of optical coherence tomography (OCT) for high-throughput analysis of the internal structure and 3D morphology of small biological objects such as vertebrate embryos

      Optical tissue clearing improves usability of optical coherence tomography (OCT) for high-throughput analysis of the internal structure and 3D morphology of small biological objects such as vertebrate embryos

      Developmental biology studies frequently require rapid analysis of the morphology of a large number of embryos (highthroughput analysis). Conventional microscopic analysis is time-consuming and, therefore, is not well suited for highthroughput analysis. OCT facilitates rapid generation of optical sections through small biological objects at high resolutions. However, due to light scattering within biological tissues, the quality of OCT images drops significantly with increasing penetration depth of the light beam. We show that optical clearing of fixed embryonic organs with methyl benzoate can significantly reduce the light scattering and, thereby, improves the usability of OCT for high-throughput analysis of embryonic morphology.

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    17. Feature Of The Week 2/23/14: Texas A&M University Reports on In vivo Pump-Probe Optical Coherence Tomography Imaging in Xenopus Laevis

      Feature Of The Week 2/23/14: Texas A&M University Reports on In vivo Pump-Probe Optical Coherence Tomography Imaging in Xenopus Laevis

      Currently, optical coherence tomography (OCT), is not capable of obtaining molecular information often crucial for identification of disease. To enable molecular imaging with OCT, we have further developed a technique that harnesses transient changes in light absorption in the sample to garner molecular information. A Fourier-domain Pump-Probe OCT (PPOCT) system utilizing a 532 nm pump and 830 nm probe has been developed for imaging hemoglobin. Methylene blue, a biological dye with well-known photophysics, was used to characterize the system before investigating the origin of the hemoglobin PPOCT signal. The first in vivo PPOCT images were recorded of the vasculature in ...

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    18. In vivo full-field en face correlation mapping optical coherence tomography

      In vivo full-field en face correlation mapping optical coherence tomography

      A full-field optical coherence tomography (OCT) system has been developed for the purpose of performing nonscanning en face flow imaging. The light source is centered at 840 nm with a bandwidth of 50 nm resulting in an axial resolution of 8 μ m in air. Microscope objectives with a numerical aperture of 0.1 were incorporated giving a transverse resolution of 5 μ m. A magnification of 5.65 was measured, resulting in a field of view of 1260 × 945     μ m . Pairs of interference fringe images are captured with opposing phase and a two-step phase image reconstruction method is applied to reconstruct ...

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    19. In vivo pump-probe optical coherence tomography imaging in Xenopus laevis

      In vivo pump-probe optical coherence tomography imaging in Xenopus laevis

      Currently, optical coherence tomography (OCT), is not capable of obtaining molecular information often crucial for identification of disease. To enable molecular imaging with OCT, we have further developed a technique that harnesses transient changes in light absorption in the sample to garner molecular information. A Fourier-domain Pump-Probe OCT (PPOCT) system utilizing a 532 nm pump and 830 nm probe has been developed for imaging hemoglobin. Methylene blue, a biological dye with well-know photophysics, was used to characterize the system before investigating the origin of the hemoglobin PPOCT signal. The first in vivo PPOCT images were recorded of the vasculature in ...

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    20. Characterization of Light Lesion Paradigms and Optical Coherence Tomography as Tools to Study Adult Retina Regeneration in Zebrafish

      Characterization of Light Lesion Paradigms and Optical Coherence Tomography as Tools to Study Adult Retina Regeneration in Zebrafish

      Light-induced lesions are a powerful tool to study the amazing ability of photoreceptors to regenerate in the adult zebrafish retina. However, the specificity of the lesion towards photoreceptors or regional differences within the retina are still incompletely understood. We therefore characterized the process of degeneration and regeneration in an established paradigm, using intense white light from a fluorescence lamp on swimming fish (diffuse light lesion). We also designed a new light lesion paradigm where light is focused through a microscope onto the retina of an immobilized fish (focused light lesion). Focused light lesion has the advantage of creating a locally ...

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    21. Ethanol exposure alters early cardiac function in the looping heart: a mechanism for congenital heart defects?

      Ethanol exposure alters early cardiac function in the looping heart: a mechanism for congenital heart defects?

      Alcohol-induced congenital heart defects (CHDs) are frequently among the most life-threatening and require surgical correction in newborns. The etiology of these defects, collectively known as Fetal Alcohol Syndrome (FAS), has been the focus of much study, particularly involving cellular and molecular mechanisms. Few studies have addressed the influential role of altered cardiac function in early embryogenesis, due to a lack of tools with the capability to assay tiny beating hearts. To overcome this gap in our understanding, we used optical coherence tomography (OCT), a non-destructive imaging modality capable of micrometer-scale resolution imaging, to rapidly and accurately map cardiovascular structure and ...

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    22. En face optical coherence tomography of transient light response at photoreceptor outer segments in living frog eyecup

      En face optical coherence tomography of transient light response at photoreceptor outer segments in living frog eyecup

      This study was designed to test the feasibility of en face mapping of the transient intrinsic optical signal (IOS) response at photoreceptor outer segments and to assess the effect of spatial resolution on functional IOS imaging of retinal photoreceptors. A line-scan optical coherence tomography (LS-OCT) was constructed to achieve depth-resolved functional IOS imaging of living frog eyecups. Rapid en face OCT revealed transient IOS almost immediately ( < 3     ms ) after the onset of visible light flashes at photoreceptor outer segments. Quantitative analysis indicated that the IOS kinetics may reflect dynamics of G-protein binding and releasing in early phases of visual transduction ...

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    23. Disruption of Sarcoendoplasmic Reticulum Calcium ATPase Function in Drosophila Leads to Cardiac Dysfunction

      Disruption of Sarcoendoplasmic Reticulum Calcium ATPase Function in Drosophila Leads to Cardiac Dysfunction

      Abnormal sarcoendoplasmic reticulum Calcium ATPase (SERCA) function has been associated with poor cardiac function in humans. While modifiers of SERCA function have been identified and studied using animal models, further investigation has been limited by the absence of a model system that is amenable to large-scale genetic screens. Drosophila melanogaster is an ideal model system for the investigation of SERCA function due to the significant homology to human SERCA and the availability of versatile genetic screening tools. To further the use of Drosophila as a model for examining the role of SERCA in cardiac function, we examined cardiac function in ...

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    24. Necessity of angiotensin-converting enzyme-related gene for cardiac functions and longevity of Drosophila melanogaster assessed by optical coherence tomography

      Necessity of angiotensin-converting enzyme-related gene for cardiac functions and longevity of Drosophila melanogaster assessed by optical coherence tomography

      Prior studies have established the necessity of an angiotensin-converting enzyme-related (ACER) gene for heart morphogenesis of Drosophila . Nevertheless, the physiology of ACER has yet to be comprehensively understood. Herein, we employed RNA interference to down-regulate the expression of ACER in Drosophila’s heart and swept source optical coherence tomography to assess whether ACER is required for cardiac functions in living adult flies. Several contractile parameters of Drosophila heart, including the heart rate (HR), end-diastolic diameter (EDD), end-systolic diameter (ESD), percent fractional shortening (%FS), and stress-induced cardiac performance, are shown, which are age dependent. These age-dependent cardiac functions declined significantly when ...

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      Mentions: Wen-Chuan Kuo
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