1. Articles in category: Developmental Biology

    97-120 of 237 « 1 2 3 4 5 6 7 8 9 10 »
    1. 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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    2. 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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    3. 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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    4. 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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    5. 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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    6. 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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    7. 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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    8. 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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    9. 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
    10. Translational paradigms in scientific and clinical imaging of cardiac development

      Translational paradigms in scientific and clinical imaging of cardiac development

      Congenital heart defects (CHD) are the most prevalent congenital disease, with 45% of deaths resulting from a congenital defect due to a cardiac malformation. Clinically significant CHD permit survival upon birth, but may become immediately life threatening. Advances in surgical intervention have significantly reduced perinatal mortality, but the outcome for many malformations is bleak. Furthermore, patients living while tolerating a CHD often acquire additional complications due to the long-term systemic blood flow changes caused by even subtle anatomical abnormalities. Accurate diagnosis of defects during fetal development is critical for interventional planning and improving patient outcomes. Advances in quantitative, multidimensional imaging ...

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    11. Baylor College Receives NIH Granbt for Biomechanics of Early Mammalian Cardiogenesis

      Baylor College Receives NIH Granbt for Biomechanics of Early Mammalian Cardiogenesis

      Baylor College of Medicine received a 2013 NIH grant for $386,700 to study 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 ...

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    12. OHSU Receives NIH Grant for Dynamic Changes In The Chick Developing Heart In Response to Altered Hemodynamics

      OHSU Receives NIH Grant for Dynamic Changes In The Chick Developing Heart In Response to Altered Hemodynamics

      Oregon Health and Science University received a 2013 NIH Grant for $405,572 for Dynamic Changes In The Chick Developing Heart In Response to Altered Hemodynamics. The principal investigator is Sandra Rugonyi. The program started in 2008 and lends in 2018. A summary of the program is given below. 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. 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 Received a 2013 NIH Grant for $620,585 for Integrated Imaging of The Form and Function of The Beating Embryonic Heart. The principle investigator is Andrew Rollins. The program began in 2006 and ends in 2017. Below is a summary of the proposed study. 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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    14. High-resolution optical coherence tomography in mouse models of genetic and induced retinal degeneration

      High-resolution optical coherence tomography in mouse models of genetic and induced retinal degeneration

      For the study of disease mechanisms and the development of novel therapeutic strategies for retinal pathologies in human, rodent models play an important role. Nowadays, optical coherence tomography (OCT) allows three-dimensional investigation of retinal events over time. However, a detailed analysis of how different retinal degenerations are reflected in OCT images is still lacking in the biomedical field. Therefore, we use OCT to visualize retinal degeneration in specific mouse models in order to study disease progression in vivo and improve image interpretation of this noninvasive modality. We use a self-developed spectral domain OCT system for simultaneous dual-band imaging in the ...

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    15. Alterations in Pulse Wave Propagation Reflect the Degree of Outflow Tract Banding in HH18 Chicken Embryos

      Alterations in Pulse Wave Propagation Reflect the Degree of Outflow Tract Banding in HH18 Chicken Embryos

      Hemodynamic conditions play a critical role in embryonic cardiovascular development, and altered blood flow leads to congenital heart defects. Chicken embryos are frequently used as models of cardiac development, with abnormal blood flow achieved through surgical interventions such as outflow tract (OFT) banding, in which a suture is tightened around the heart OFT to restrict blood flow. Banding in embryos increases blood pressure and alters blood flow dynamics, leading to cardiac malformations similar to those seen in human congenital heart disease. In studying these hemodynamic changes, synchronization of data to the cardiac cycle is challenging, and alterations in the timing ...

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    16. 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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    17. 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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    18. 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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    19. 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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    20. 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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    21. 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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    22. 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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    23. 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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    24. 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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    97-120 of 237 « 1 2 3 4 5 6 7 8 9 10 »
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