1. Articles in category: Developmental Biology

    169-192 of 244 « 1 2 ... 5 6 7 8 9 10 11 »
    1. Tracking Morphogenetic Tissue Deformations in the Early Chick Embryo

      Tracking Morphogenetic Tissue Deformations in the Early Chick Embryo
      Embryonic epithelia undergo complex deformations (e.g. bending, twisting, folding, and stretching) to form the primitive organs of the early embryo. Tracking fiducial markers on the surfaces of these cellular sheets is a well-established method for estimating morphogenetic quantities such as growth, contraction, and shear. However, not all surface labeling techniques are readily adaptable to conventional imaging modalities and possess different advantages and limitations. Here, we describe two labeling methods and illustrate the utility of each technique. In the first method, hundreds of fluorescent labels are applied simultaneously to the embryo using magnetic iron particles. These labels are then used ...
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    2. Feature Of The Week 10/9/11: Researchers at RWTH Aachen University Demonstrate Increased Tissue Contrast Using High-Resolution Simultaneous Dual-Band 3D OCT

      Feature Of The Week 10/9/11: Researchers at RWTH Aachen University Demonstrate Increased Tissue Contrast Using High-Resolution Simultaneous Dual-Band 3D OCT
      Classical Optical Coherence Tomography (OCT) systems represent morphological information by displaying the backscattered intensity of the OCT signal. Functional methods like spectroscopic OCT have been developed, extending the contrasting capabilities beyond morphological information. Spectroscopic information arises from wavelength dependent tissue features and has been retrieved by a time-frequency analysis of the OCT signal. However, this method requires high computational effort and is restricted to one wavelength band only.In contrast to a time frequency analysis, detecting in two distinct wavelength bands allows for covering large spectral bandwidths. Contrast enhancement is possible by encoding the spectral differences between both images into ...
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    3. Optical Coherence Tomography for live imaging of mammalian development

      Optical Coherence Tomography for live imaging of mammalian development
      Understanding the nature and mechanism of congenital defects of the different organ systems in humans has heavily relied on the analysis of the corresponding mutant phenotypes in rodent models. Optical Coherence Tomography (OCT) has recently emerged as a powerful tool to study early embryonic development. This non-invasive optical methodology does not require labeling and allows visualization of embryonic tissues with single cell resolution. Here, we will discuss how OCT can be applied for structural imaging of early mouse and rat embryos in static culture, cardiodynamic and blood flow analysis, and in utero embryonic imaging at later stages of gestation, demonstrating ...
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    4. Noninvasive imaging of ethanol-induced developmental defects in zebrafish embryos using optical coherence tomography

      Noninvasive imaging of ethanol-induced developmental defects in zebrafish embryos using optical coherence tomography
      In this article, we report the use of optical coherence tomography for noninvasive cross-sectional real-time imaging of ethanol-induced developmental defects in zebrafish embryos larvae. For ethanol concentration of over 300 mM, developmental defects of eye (shrinkage and retinal abnormalities), malformation of the notochord and ataxia arising due to the toxic effects of ethanol were observed in OCT images from 3 days post fertilization onwards. The results suggest that OCT could be a valuable tool for noninvasive assessment of birth defects in small animal systems.
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    5. Increasing the field-of-view of dynamic cardiac OCT via post-acquisition mosaicing without affecting frame-rate or spatial resolution

      Increasing the field-of-view of dynamic cardiac OCT via post-acquisition mosaicing without affecting frame-rate or spatial resolution
      Optical coherence tomography (OCT) allows imaging dynamic structures and fluid flow within scattering tissue, such as the beating heart and blood flow in murine embryos. For any given system, the frame rate, spatial resolution, field-of-view (FOV), and signal-to-noise ratio (SNR) are interconnected: favoring one aspect limits at least one of the others due to optical, instrumentation, and software constraints. Here we describe a spatio-temporal mosaicing technique to reconstruct high-speed, high spatial-resolution, and large-field-of-view OCT sequences. The technique is applicable to imaging any cyclically moving structure and operates on multiple, spatially overlapping tiled image sequences (each sequence acquired sequentially at a ...
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    6. Rh-I-UEA-1 Polymerized Liposomes Target and Image Adenomatous Polyps in the APCMin/+ Mouse Using Optical Colonography

      Rh-I-UEA-1 Polymerized Liposomes Target and Image Adenomatous Polyps in the APCMin/+ Mouse Using Optical Colonography
      Mutated adenomatous polyposis coli (APC) genes predispose transformations to neoplasia, progressing to colorectal carcinoma. Early detection facilitates clinical management and therapy. Novel lectin-mediated polymerized targeted liposomes (Rh-I-UEA-1), with polyp specificity and incorporated imaging agents were fabricated to locate and image adenomatous polyps in APCMin/+ mice. The biomarker α-l-fucose covalently joins the liposomal conjugated lectin Ulexeuropaeus agglutinin (UEA-1), via glycosidic linkage to the polyp mucin layer. Multispectral optical imaging (MSI) corroborated a global perspective of specific binding (rhodamine B 532 nm emission, 590–620 nm excitation) of targeted Rh-I-UEA-1 polymerized liposomes to polyps with 1.4-fold labeling efficiency. High-resolution coregistered optical ...
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    7. Microfluidic characterization of cilia-driven fluid flow using optical coherence tomography-based particle tracking velocimetry

      Microfluidic characterization of cilia-driven fluid flow using optical coherence tomography-based particle tracking velocimetry
      Motile cilia are cellular organelles that generate directional fluid flow across various epithelial surfaces including the embryonic node and respiratory mucosa. The proper functioning of cilia is necessary for normal embryo development and, for the respiratory system, the clearance of mucus and potentially harmful particulate matter. Here we show that optical coherence tomography (OCT) is well-suited for quantitatively characterizing the microfluidic-scale flow generated by motile cilia. Our imaging focuses on the ciliated epithelium of Xenopus tropicalis embryos, a genetically manipulable and experimentally tractable animal model of human disease. We show qualitative flow profile characterization using OCT-based particle pathline imaging. We ...
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    8. Case Western Reserve University Receives NIH Award to Investigate The Early Embryonic Murine Heart Using Optical Coherence Tomography.

      Case Western Reserve University Receives NIH Award to Investigate The Early Embryonic Murine Heart Using Optical Coherence Tomography.
      Case Western Reserve University Received $720k from the National Heart Lung and Blood Institute of the NIH to Investigate The Early Embryonic Murine Heart Using Optical Coherence Tomography. The principal investigator is Andrew Rollins. This is a four year program that started in 2008 and ends in 2012 and this is the third-year of funding.
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    9. Baylor College of Medicine Receive NIH award for Phenotyping Embryonic Mammalian Heart Function using OCT

      Baylor College of Medicine Receive NIH award for Phenotyping Embryonic Mammalian Heart Function using OCT
      Baylor College of Medicine received $419k from the Microscope Imaging Study Section of the NIH to investigate Phenotyping Embryonic Mammalian Heart Function using OCT. The principal investigator is Mary Dickinson. The program starts in 2011 and ends in 2013. Below is a brief description of the proposed work.
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    10. Integration of an Optical Coherence Tomography (OCT) System into an Examination Incubator to facilitate in vivo Imaging of Cardiovascular Development in higher vertebrate Embryos under stable physiological Conditions

      Integration of an Optical Coherence Tomography (OCT) System into an Examination Incubator to facilitate in vivo Imaging of Cardiovascular Development in higher vertebrate Embryos under stable physiological Conditions
      High-resolution in vivo imaging of higher vertebrate embryos over short or long time periods under constant physiological conditions is a technically challenging task for researchers working on cardiovascular development. In chick embryos, for example, various studies have shown that without appropriate maintenance of temperature, as one of the main environmental factors, the embryonic heart rate drops rapidly and often results in an increase in regurgitant flow. Hemodynamic parameters are critical stimuli for cardiovascular development that, for a correct evaluation of their developmental significance, should be documented under physiological conditions. However, previous studies were mostly carried out outside of an incubator ...
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    11. Measurement of strain and strain rate in embryonic chick heart in vivo using spectral domain optical coherence tomography

      Measurement of strain and strain rate in embryonic chick heart in vivo using spectral domain optical coherence tomography

      The ability to measure in vivo strain and strain rate in embryonic chick heart is one of the key requirements for understanding the mechanisms of cardiac development. Due to its high temporal and spatial resolution as well as its fast imaging capability, optical coherence tomography (OCT) has the potential to reveal the complex myocardial activity in the living chick heart. We describe a method to evaluate the in vivo strain and strain rate of the myocardium through analyzing the periodic variation of the myocardial wall thickness calculated from real time serial OCT images. The results demonstrate that OCT can be ...

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    12. Changes in the Expression of the Alzheimer's Disease-Associated Presenilin Gene in Drosophila Heart Leads to Cardiac Dysfunction

      Changes in the Expression of the Alzheimer's Disease-Associated Presenilin Gene in Drosophila Heart Leads to Cardiac Dysfunction
      Mutations in the presenilin genes cause the majority of early-onset familial Alzheimer's disease. Recently, presenilin mutations have been identified in patients with dilated cardiomyopathy (DCM), a common cause of heart failure and the most prevalent diagnosis in cardiac transplantation patients. However, the molecular mechanisms, by which presenilin mutations lead to either AD or DCM, are not yet understood. We have employed transgenic Drosophila models and optical coherence tomography imaging technology to analyze cardiac function in live adult Drosophila. Silencing of Drosophila ortholog of presenilins (dPsn) led to significantly reduced heart rate and remarkably age-dependent increase in end-diastolic vertical dimensions ...
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    13. Live imaging of mammalian embryonic development

      Live imaging of mammalian embryonic development
      Understanding the genetic basis of congenital heart defects in humans relies on the analysis of mammalian model systems, such as mouse and rat embryos. Hundreds of mouse mutant analogs of human birth defects and diseases have been reported, helping to advance our understanding. However, the primary structural characterization of these mutant phenotypes has been based on static analysis of histological sections. Since the major function of the heart is to pump blood, static analysis does not provide information about blood flow patterns. As a result, very little is known about the cardiodynamic processes of early embryonic mammalian development. Thus, there ...
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    14. Observations of cardiac beating behaviors of wild-type and mutant Drosophilae with optical coherence tomography

      Observations of cardiac beating behaviors of wild-type and mutant Drosophilae with optical coherence tomography
      Time-resolved optical coherence tomography (OCT) scanning images of wild-type and mutant fruit flies (Drosophila melanogaster), illustrating the heartbeat patterns for evaluating their cardiac functions, are demonstrated. Based on the heartbeat patterns, the beat rate and the relative phase between the first two heart segments can be evaluated. The OCT scanning results of mutant flies with impaired proteasome function in cardiac muscles show irregular heartbeat patterns and systematically decreased average beat rates, when compared with the regular patterns of ∼4.97 beats/s in average beat rate of the wild-type. In both wild-type and proteasome mutant flies, the beatings at different ...
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    15. Neurologic and ocular phenotype in Pitt-Hopkins syndrome and a zebrafish model

      Neurologic and ocular phenotype in Pitt-Hopkins syndrome and a zebrafish model
      In this study, we performed an in-depth analysis of the neurologic and ophthalmologic phenotype in a patient with Pitt–Hopkins syndrome (PTHS), a disorder characterized by severe mental and motor retardation, carrying a uniallelic TCF4 deletion, and studied a zebrafish model. The PTHS-patient was characterized by high-resolution magnetic resonance imaging (MRI) with diffusion tensor imaging to analyze the brain structurally, spectral-domain optical coherence tomography to visualize the retinal layers, and electroretinography to evaluate retinal function. A zebrafish model was generated by knockdown of tcf4-function by injection of morpholino antisense oligos into zebrafish embryos and the morphant phenotype was characterized for ...
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    16. Feature Of The Week 4/17/11: Researchers Study Fundamental Aspects of Embryonic Heart Development Using OCT

      Feature Of The Week 4/17/11: Researchers Study Fundamental Aspects of Embryonic Heart Development Using OCT
      Feature Of The Week 4/17/11: Researchers from the University of South Florida, Western Reserve University , and the Massachusetts Institute of Technology use 4-D OCT to study fundamental aspects of embryonic heart development during the morphogenesis of a single chamber heart to a four chamber heart. Below, courtesy of Dr. Kersti Linask, is a visual, audio, and text summary of that work. Please click "full screen" and also click the speaker symbol in the lower right hand corner to hear narration. The volume can also be adjusted from the lower right hand corner.Cells that will become cardiac cells ...
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    17. Feature Of The Week 4/10/11: Dr. Kirill Larin Narrates a Presentation on OCT Imaging of In Utero Embryonic Development

      Feature Of The Week 4/10/11: Dr. Kirill Larin Narrates a Presentation on OCT Imaging of In Utero Embryonic Development
      Feature Of The Week 4/10/11: Dr. Kirill Larin narrates a presentation of execptional work from researchers at the Baylor College of Medicine and University of Houston on the use of Optical Coherence Tomography for high resolution imaging of mouse development in utero.   Understanding of the genetic basis of human birth defects heavily relies on analysis of mouse embryos. The success of these efforts depends on the ability to visualize and analyze phenotypic outcomes of genetic manipulations and pharmacological treatments.  A number of in vivo imaging methods have been developed to study mouse embryonic development, such as high-frequency ultrasound ...
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    18. Live Imaging of Mouse Embryos

      Live Imaging of Mouse Embryos
      The development of the mouse embryo is a dynamic process that requires the spatial and temporal coordination of multiple cell types as they migrate, proliferate, undergo apoptosis, and differentiate to form complex structures. However, the confined nature of embryos as they develop in utero limits our ability to observe these morphogenetic events in vivo. Previous work has used fixed samples and histological methods such as immunofluorescence or in situ hybridization to address expression or localization of a gene of interest within a developmental time line. However, such methods do not allow us to follow the complex, dynamic movements of individual ...
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    19. Optical coherence tomography for high-resolution imaging of mouse development in utero

      Optical coherence tomography for high-resolution imaging of mouse development in utero
      Although the mouse is a superior model to study mammalian embryonic development, high-resolution live dynamic visualization of mouse embryos remain a technical challenge. We present optical coherence tomography as a novel methodology for live imaging of mouse embryos through the uterine wall thereby allowing for time lapse analysis of developmental processes and direct phenotypic analysis of developing embryos. We assessed the capability of the proposed methodology to visualize structures of the living embryo from embryonic stages 12.5 to 18.5 days postcoitus. Repetitive in utero embryonic imaging is demonstrated. Our work opens the door for a wide range of ...
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    20. Function and form in the developing cardiovascular system

      Function and form in the developing cardiovascular system

      Function of the developing heart is dictated by changes in its morphology. For simplicity, we distinguish four stages with different contraction mechanics and conduction parameters. Straight or looped tubular hearts, similar to those of invertebrates such as Drosophila or Ciona, operate as suction pumps and are characterized by a caudally localized pacemaker and slow, peristaltoid conduction and contraction. There is a complete occlusion of the lumen during systole. When the atrial and ventricular chambers appear, the preseptation heart is in many functional aspects similar to the adult heart, but the same function is achieved by different means. There are parallels ...

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    21. Bioptigen OCT Captures the Hyper-Reflective Cone Mosaic in Zebrafish Retina

      Bioptigen OCT Captures the Hyper-Reflective Cone Mosaic in Zebrafish Retina
      Bioptigen Press Release: Bioptigen demonstrates the application of a commercial SDOCT system to imaging the whole eye of the adult zebrafish. Images of the cornea, iris, lens, vitreous, retina, and cone mosaic are shown in the attached presentation. The Bioptigen SDOIS system is implemented with the handheld scanner mounted vertically, pointing down. First, an alert zebrafish is placed in a cuvette with anesthesia and ceases to move within 30 seconds. The cuvette is placed on a 5-axis stereotactic mount (Bioptigen ZAS accessory) and positioned to co-align the nodal point of the raster scan, the geometrical nodal point of the stage ...
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      Mentions: Bioptigen
    22. Non-invasive imaging and monitoring of rodent retina using simultaneous dual-band optical coherence tomography

      Non-invasive imaging and monitoring of rodent retina using simultaneous dual-band optical coherence tomography

      Spectral domain dual-band optical coherence tomography for simultaneous imaging of rodent retina in the 0.8 μm and 1.3 μm wavelength region and non-invasive monitoring of the posterior eye microstructure in the field of retinal degeneration research is demonstrated. The system is illuminated by a supercontinuum laser source and allows three-dimensional imaging with high axial resolution better than 3.8 μm and 5.3 μm in tissue at 800 nm and 1250 nm, respectively, for precise retinal thickness measurements. A fan-shaped scanning pattern with the pivot point close to the eye's pupil and a contact lens are applied ...

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    23. SMAD signaling drives heart and muscle dysfunction in a Drosophila model of muscular dystrophy

      SMAD signaling drives heart and muscle dysfunction in a Drosophila model of muscular dystrophy
      Loss-of-function mutations in the genes encoding dystrophin and the associated membrane proteins, the sarcoglycans, produce muscular dystrophy and cardiomyopathy. The dystrophin complex provides stability to the plasma membrane of striated muscle during muscle contraction. Increased SMAD signaling due to activation of the transforming growth factor-β (TGFβ) pathway has been described in muscular dystrophy; however, it is not known whether this canonical TGFβ signaling is pathogenic in the muscle itself. Drosophila deleted for the γ/δ-sarcoglycan gene (Sgcd) develop progressive muscle and heart dysfunction and serve as a model for the human disorder. We used dad-lacZ flies to demonstrate the signature ...
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    24. Optical Coherence Tomography Imaging of Early Quail Embryos

      Optical Coherence Tomography Imaging of Early Quail Embryos
      Congenital heart defects (CHDs) affect thousands of newborns each year in the United States. Recent research using animal model systems indicates that the abnormal function of the early tubular heart precedes structural defects such as septal defects. Optical coherence tomography (OCT) is an imaging modality that can provide high spatial and temporal resolution to study both the structure and the function of the tubular heart. With technical advances in OCT imaging speed, especially with frequency domain OCT and image-based retrospective gating, it is now possible to image a beating avian embryonic heart in three dimensions under physiological conditions and follow ...
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    169-192 of 244 « 1 2 ... 5 6 7 8 9 10 11 »
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