1. Articles in category: Developmental Biology

    193-216 of 258 « 1 2 ... 6 7 8 9 10 11 »
    1. 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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    2. 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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    3. 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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    4. 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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    5. 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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    6. 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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    7. 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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    8. 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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    9. 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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    10. 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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    11. 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
    12. 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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    13. 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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    14. 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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    15. High-Speed Optical Coherence Tomography Imaging of the Beating Avian Embryonic Heart

      High-Speed Optical Coherence Tomography Imaging of the Beating Avian Embryonic Heart
      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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    16. Speckle variance OCT imaging of the vasculature in live mammalian embryos

      Speckle variance OCT imaging of the vasculature in live mammalian embryos

      Live imaging of normal and abnormal vascular development in mammalian embryos is important tool in embryonic research, which can potentially contribute to understanding, prevention and treatment of cardiovascular birth defects. Here, we used speckle variance analysis of swept source optical coherence tomography (OCT) data sets acquired from live mouse embryos to reconstruct the 3-D structure of the embryonic vasculature. Both Doppler OCT and speckle variance algorithms were used to reconstruct the vascular structure. The results demonstrates that speckle variance imaging provides more accurate representation of the vascular structure, as it is not sensitive to the blood flow direction, while the ...

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    17. Physiological homology between Drosophila melanogaster and vertebrate cardiovascular systems

      Physiological homology between Drosophila melanogaster and vertebrate cardiovascular systems
      The physiology of the Drosophila melanogaster cardiovascular system remains poorly characterized compared with its vertebrate counterparts. Basic measures of physiological performance remain unknown. It also is unclear whether subtle physiological defects observed in the human cardiovascular system can be reproduced in D. melanogaster. Here we characterize the cardiovascular physiology of D. melanogaster in its pre-pupal stage by using high-speed dye angiography and optical coherence tomography. The heart has vigorous pulsatile contractions that drive intracardiac, aortic and extracellular-extravascular hemolymph flow. Several physiological measures, including weight-adjusted cardiac output, body-length-adjusted aortic velocities and intracardiac shear forces, are similar to those in the closed ...
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    18. Arrhythmia Caused by a Drosophila Tropomyosin Mutation Is Revealed Using a Novel Optical Coherence Tomography Instrument

      Arrhythmia Caused by a Drosophila Tropomyosin Mutation Is Revealed Using a Novel Optical Coherence Tomography Instrument
      Background Dilated cardiomyopathy (DCM) is a severe cardiac condition that causes high mortality. Many genes have been confirmed to be involved in this disease. An ideal system with which to uncover disease mechanisms would be one that can measure the changes in a wide range of cardiac activities associated with mutations in specific, diversely functional cardiac genes. Such a system needs a genetically manipulable model organism that allows in vivo measurement of cardiac phenotypes and a detecting instrument capable of recording multiple phenotype parameters. Methodology and Principal Findings With a simple heart, a transparent body surface at larval stages and ...
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    19. Measuring hemodynamics in the developing heart tube with four-dimensional gated Doppler optical coherence tomography

      Measuring hemodynamics in the developing heart tube with four-dimensional gated Doppler optical coherence tomography

      Hemodynamics is thought to play a major role in heart development, yet tools to quantitatively assess hemodynamics in the embryo are sorely lacking. The especially challenging analysis of hemodynamics in the early embryo requires new technology. Small changes in blood flow could indicate when anomalies are initiated even before structural changes can be detected. Furthermore, small changes in the early embryo that affect blood flow could lead to profound abnormalities at later stages. We present a demonstration of 4-D Doppler optical coherence tomography (OCT) imaging of structure and flow, and present several new hemodynamic measurements on embryonic avian hearts at ...

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    20. Heart wall velocimetry and exogenous contrast-based cardiac flow imaging in Drosophila melanogaster using Doppler optical coherence tomography

      Heart wall velocimetry and exogenous contrast-based cardiac flow imaging in Drosophila melanogaster using Doppler optical coherence tomography
      Drosophila melanogaster (fruit fly) is a central organism in biology and is becoming increasingly important in the cardiovascular sciences. Prior work in optical imaging of the D. melanogaster heart has focused on static and dynamic structural anatomy. In the study, it is demonstrated that Doppler optical coherence tomography can quantify dynamic heart wall velocity and hemolymph flow in adult D. melanogaster. Since hemolymph is optically transparent, a novel exogenous contrast technique is demonstrated to increase the backscatter-based intracardiac Doppler flow signal. The results presented here open up new possibilities for functional cardiovascular phenotyping of normal and mutant D. melanogaster.
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    21. Mechanics of head fold formation: investigating tissue-level forces forces during early development

      Mechanics of head fold formation: investigating tissue-level forces forces during early development
      During its earliest stages, the avian embryo is approximately planar. Through a complex series of folds, this flat geometry is transformed into the intricate three-dimensional structure of the developing organism. Formation of the head fold (HF) is the first step in this cascading sequence of out-of-plane tissue folds. The HF establishes the anterior extent of the embryo and initiates heart, foregut and brain development. Here, we use a combination of computational modeling and experiments to determine the physical forces that drive HF formation. Using chick embryos cultured ex ovo, we measured: (1) changes in tissue morphology in living embryos using ...
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    22. Imaging modalities to assess structural birth defects in mutant mouse models

      Imaging modalities to assess structural birth defects in mutant mouse models
      Assessment of structural birth defects (SBDs) in animal models usually entails conducting detailed necropsy for anatomical defects followed by histological analysis for tissue defects. Recent advances in new imaging technologies have provided the means for rapid phenotyping of SBDs, such as using ultra-high frequency ultrasound biomicroscopy, optical coherence tomography, micro-CT, and micro-MRI. These imaging modalities allow the detailed assessment of organ/tissue structure, and with ultrasound biomicroscopy, structure and function of the cardiovascular system also can be assessed noninvasively, allowing the longitudinal tracking of the fetus in utero. In this review, we briefly discuss the application of these state-of-the-art imaging ...
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    23. Measurement of absolute blood flow velocity in outflow tract of HH18 chicken embryo based on 4D reconstruction using spectral domain optical coherence tomography

      Measurement of absolute blood flow velocity in outflow tract of HH18 chicken embryo based on 4D reconstruction using spectral domain optical coherence tomography

      The measurement of blood-plasma absolute velocity distributions with high spatial and temporal resolution in vivo is important for the investigation of embryonic heart at its early stage of development. We introduce a novel method to measure absolute blood flow velocity based on high speed spectral domain optical coherence tomography (OCT) and apply it to measure velocities across the heart outflow tract (OFT) of a chicken embryo (stage HH18). First, we use the OCT system to acquire 4D 
[(x,y,z) + t] images of the OFT in vivo. Second, we reconstruct the 4D microstructural images and obtain the orientation of the ...

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    24. Optical coherence tomography as approach for the minimal invasive localization of the germinal disc in ovo before chicken sexing

      Optical coherence tomography as approach for the minimal invasive localization of the germinal disc in ovo before chicken sexing
      In most industrial states a huge amount of newly hatched male layer chickens are usually killed immediately after hatching by maceration or gassing. The reason for killing most of the male chickens of egg producing races is their slow growth rate compared to races specialized on meat production. When the egg has been laid, the egg contains already a small disc of cells on the surface of the yolk known as the blastoderm. This region is about 4 - 5 mm in diameter and contains the information whether the chick becomes male or female and hence allows sexing of the chicks ...
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    193-216 of 258 « 1 2 ... 6 7 8 9 10 11 »
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