1. Articles in category: Developmental Biology

    49-72 of 237 « 1 2 3 4 5 6 7 8 9 10 »
    1. Direct four-dimensional structural and functional imaging of cardiovascular dynamics in mouse embryos with 1.5  MHz optical coherence tomography

      Direct four-dimensional structural and functional imaging of cardiovascular dynamics in mouse embryos with 1.5  MHz optical coherence tomography

      High-resolution three-dimensional (3D) imaging of cardiovascular dynamics in mouse embryos is greatly desired to study mammalian congenital cardiac defects. Here, we demonstrate direct four-dimensional (4D) imaging of the cardiovascular structure and function in live mouse embryos at a ∼ 43     Hz volume rate using an optical coherence tomography (OCT) system with a ∼ 1.5     MHz Fourier domain mode-locking swept laser source. Combining ultrafast OCT imaging with live mouse embryo culture protocols, 3D volumes of the embryo are directly and continuously acquired over time for a cardiodynamics analysis without the application of any synchronization algorithms. We present the time-resolved measurements of the ...

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    2. Optogenetic pacing in Drosophila melanogaster

      Optogenetic pacing in Drosophila melanogaster

      Electrical stimulation is currently the gold standard for cardiac pacing. However, it is invasive and nonspecific for cardiac tissues. We recently developed a noninvasive cardiac pacing technique using optogenetic tools, which are widely used in neuroscience. Optogenetic pacing of the heart provides high spatial and temporal precisions, is specific for cardiac tissues, avoids artifacts associated with electrical stimulation, and therefore promises to be a powerful tool in basic cardiac research. We demonstrated optogenetic control of heart rhythm in a well-established model organism, Drosophila melanogaster . We developed transgenic flies expressing a light-gated cation channel, channelrhodopsin-2 (ChR2), specifically in their hearts and ...

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    3. 4D subject-specific inverse modeling of the chick embryonic heart outflow tract hemodynamics

      4D subject-specific inverse modeling of the chick embryonic heart outflow tract hemodynamics

      Blood flow plays a critical role in regulating embryonic cardiac growth and development, with altered flow leading to congenital heart disease. Progress in the field, however, is hindered by a lack of quantification of hemodynamic conditions in the developing heart. In this study, we present a methodology to quantify blood flow dynamics in the embryonic heart using subject-specific computational fluid dynamics (CFD) models. While the methodology is general, we focused on a model of the chick embryonic heart outflow tract (OFT), which distally connects the heart to the arterial system, and is the region of origin of many congenital cardiac ...

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    4. A Circadian Clock Gene, Cry, Affects Heart Morphogenesis and Function in Drosophila as Revealed by Optical Coherence Microscopy

      A Circadian Clock Gene, Cry, Affects Heart Morphogenesis and Function in Drosophila as Revealed by Optical Coherence Microscopy

      Circadian rhythms are endogenous, entrainable oscillations of physical, mental and behavioural processes in response to local environmental cues such as daylight, which are present in the living beings, including humans. Circadian rhythms have been related to cardiovascular function and pathology. However, the role that circadian clock genes play in heart development and function in a whole animal in vivo are poorly understood. The Drosophila cryptochrome (dCry) is a circadian clock gene that encodes a major component of the circadian clock negative feedback loop. Compared to the embryonic stage, the relative expression levels of dCry showed a significant increase (>100-fold) in ...

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    5. Label-free characterization of vitrification-induced morphology changes in single-cell embryos with full-field optical coherence tomography

      Label-free characterization of vitrification-induced morphology changes in single-cell embryos with full-field optical coherence tomography

      Vitrification is an increasingly popular method of embryo cryopreservation that is used in assisted reproductive technology. Although vitrification has high post-thaw survival rates compared to other freezing techniques, its long-term effects on embryo development are still poorly understood. We demonstrate an application of full-field optical coherence tomography (FF-OCT) to visualize the effects of vitrification on live single-cell (2 pronuclear) mouse embryos without harmful labels. Using FF-OCT, we observed that vitrification causes a significant increase in the aggregation of structures within the embryo cytoplasm, consistent with reports in literature based on fluorescence techniques. We quantify the degree of aggregation with an ...

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    6. Internal physiology of live krill revealed using new aquaria techniques and mixed optical microscopy and optical coherence tomography (OCT) imaging techniques

      Internal physiology of live krill revealed using new aquaria techniques and mixed optical microscopy and optical coherence tomography (OCT) imaging techniques

      The accurate observation of physiological changes on in vivo samples of important animal species such as Euphausia superba (Antarctic krill) is an important goal in helping to understand how environmental changes can affect animal development. Using a custom made ‘krill trap’, live un-anaesthetized krill were confined for seven hours, during which three hours of optical imaging were obtained and no subsequent ill effects observed. The trap enabled two imaging methods to be employed: optical coherence tomography (OCT) and microscopy. OCT enabled internal structure and tissues to be imaged to a depth of approximately 2 mm and resolution of approximately 12 ...

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    7. High-speed ultrahigh-resolution spectral domain optical coherence tomography using high-powersupercontinuum at 0.8 µm wavelength

      High-speed ultrahigh-resolution spectral domain optical coherence tomography using high-powersupercontinuum at 0.8 µm wavelength

      We demonstrated high-speed ultrahigh-resolution (UHR) optical coherence tomography (OCT) in the 800 nm wavelength region. A high-power coherent supercontinuum (SC) and a high-speed line scan camera were used to construct a spectral domain OCT. The axial resolution was 3.1 µm in air and 2.3 µm in tissue. The dependence of sensitivity on the SC power and A-scan rate was examined. For the A-scan rate of 70 kHz, the sensitivity of 104 dB was achieved for the SC power higher than 60 mW. High-speed in vivo UHR-OCT imaging was demonstrated for zebrafish embryo and swimming medaka.

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    8. 4D optical coherence tomography of aortic valve dynamics in a murine mouse model ex vivo

      4D optical coherence tomography of aortic valve dynamics in a murine mouse model ex vivo

      The heart and its mechanical components, especially the heart valves and leaflets, are under enormous strain during lifetime. Like all highly stressed materials, also these biological components undergo fatigue and signs of wear, which impinge upon cardiac output and in the end on health and living comfort of affected patients. Thereby pathophysiological changes of the aortic valve leading to calcific aortic valve stenosis (AVS) as most frequent heart valve disease in humans are of particular interest. The knowledge about changes of the dynamic behavior during the course of this disease and the possibility of early stage diagnosis could lead to ...

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    9. High-resolution three-dimensional in vivo imaging of mouse oviduct using optical coherence tomography

      High-resolution three-dimensional in vivo imaging of mouse oviduct using optical coherence tomography

      The understanding of the reproductive events and the molecular mechanisms regulating fertility and infertility in humans relies heavily on the analysis of the corresponding phenotypes in mouse models. While molecular genetic approaches provide significant insight into the molecular regulation of these processes, the lack of live imaging methods that allow for detailed visualization of the mouse reproductive organs limits our investigations of dynamic events taking place during the ovulation, the fertilization and the pre-implantation stages of embryonic development. Here we introduce an in vivo three-dimensional imaging approach for visualizing the mouse oviduct and reproductive events with micro-scale spatial resolution using ...

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    10. Mapping conduction velocity of early embryonic hearts with a robust fitting algorithm

      Mapping conduction velocity of early embryonic hearts with a robust fitting algorithm

      Cardiac conduction maturation is an important and integral component of heart development. Optical mapping with voltage-sensitive dyes allows sensitive measurements of electrophysiological signals over the entire heart. However, accurate measurements of conduction velocity during early cardiac development is typically hindered by low signal-to-noise ratio (SNR) measurements of action potentials. Here, we present a novel image processing approach based on least squares optimizations, which enables high-resolution, low-noise conduction velocity mapping of smaller tubular hearts. First, the action potential trace measured at each pixel is fit to a curve consisting of two cumulative normal distribution functions. Then, the activation time at each ...

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

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

      Case Western University Receives a 2015 NIH Grant for $359,023 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 proposed 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 altered ...

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    12. Investigating Hemodynamics of the Developing Embryonic Heart using Optical Coherence Tomography (Thesis)

      Investigating Hemodynamics of the Developing Embryonic Heart using Optical Coherence Tomography (Thesis)

      Blood flow is a critical factor that regulates developmental programs during cardiogenesis. During early embryonic development, deviations from the normal blood flow pattern have been shown to lead to congenital heart defects including septal defects and outflow tract anomalies. To better understand the role flow and the resulting hemodynamic forces play during cardiovascular development precise tools are needed to rapidly calculate and monitor these forces. Optical coherence tomography (OCT) is a noninvasive imaging modality that is well suited for imaging the developing heart due to its high spatial and temporal resolution. OCT is also capable of analyzing various cardiac functions ...

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    13. Closed loop tracked Doppler optical coherence tomography based heart monitor for the Drosophila melanogaster larvae

      Closed loop tracked Doppler optical coherence tomography based heart monitor for the Drosophila melanogaster larvae

      A fruit fly larva (top) was continuously tracked for continuous remote monitoring. A heartbeat trace of freely moving larva (bottom) was obtained by a low coherence interferometry based doppler sensing technique. This paper presents a novel instrument for biosciences, useful for studies of moving embryos. A dual sequential imaging/measurement channel is assembled via a closed-loop tracking architecture. The dual channel system can operate in two regimes: (i) single-point Doppler signal monitoring or (ii) fast 3-D swept source OCT imaging. The system is demonstrated for characterizing cardiac dynamics in Drosophila melanogaster larva. Closed loop tracking enables long term in vivo ...

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    14. Quantification of Mouse Embryonic Eye Development with Optical Coherence Tomography In Utero

      Quantification	of	Mouse	Embryonic	Eye	Development	with	 Optical	Coherence	Tomography	In	Utero

      Mouse models are commonly used as research tools to understand regulatory pathways affected by human diseases and disorders. Live imaging tools for visualization of mouse embryonic ocular tissues would be beneficial in research associated with developmental ocular defects. In this study, in utero quantitative assessment of ocular structures in mouse embryos was performed with a swept-source optical coherence tomography (SSOCT). To define developmental changes in eye morphology in live embryos, the volume of the embryonic eye lens and the globe at different embryonic stages ranging from E13.5 to E18.5 was quantified. It is determined that the major axis ...

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    15. Hybrid ultrahigh resolution optical coherence / photoacoustic microscopy

      Hybrid ultrahigh resolution optical coherence / photoacoustic microscopy

      We present an ultrahigh resolution dual modality optical resolution photoacoustic microsopy (OR-PAM) and spectral domain optical coherence microscopy (SD-OCM) system. The ultrahigh sub-micron lateral resolution is provided by the high numerical aperture of the objective lens used while the ultrahigh axial resolution is provided by the broadband OCT laser that covers 107 nm with a central wavelength of 840 nm. The synchronized simultaneous acquisition for the two modalities is achieved using a 40MHz FPGA. 2D-scanning is realized by two orthogonal translation stages (PI, 400 nm resolution). The transversal resolution of the system is 0.5 μm, the axial resolutions are ...

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    16. Measurement of wall shear stress in chick embryonic heart using optical coherence tomography

      Measurement of wall shear stress in chick embryonic heart using optical coherence tomography

      The cardiac development is a complicated process affected by genetic and environmental factors. Wall shear stress (WSS) is one of the components which have been proved to influence the morphogenesis during early stages of cardiac development. To study the mechanism, WSS measurement is a step with significant importance. WSS is caused by blood flow imposed on the inner surface of the heart wall and it can be determined by calculating velocity gradients of blood flow in a direction perpendicular to the wall. However, the WSS of the early stage embryonic heart is difficult to measure since the embryonic heart is ...

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      Mentions: Yi Wang
    17. Approach to quantify two-dimensional strain of chick embryonic heart in early stage based on spectral domain optical coherence tomography

      Approach to quantify two-dimensional strain of chick embryonic heart in early stage based on spectral domain optical coherence tomography

      The heart undergoes remarkable changes during embryonic development due to genetic programming and epigenetic influences, in which mechanical loads is a key factor. As embryonic research development, an important goal is to develop mathematical models that describe the influence of mechanics on embryonic heart development. However, basic parameters for the modeling are difficult to acquire since the embryonic heart is tiny and beating fast in the early stages. Optical coherence tomography (OCT) technique provides depth-resolved image with high resolution and high acquisition speed in a noninvasive manner. In this paper, we performed 4D[(x,y,z) + t] scan on the ...

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      Mentions: Yi Wang
    18. Comparison of optical projection tomography and optical coherence tomography for assessment of murine embryonic development

      Comparison of optical projection tomography and optical coherence tomography for assessment of murine embryonic development

      The murine model is a common model for studying developmental diseases. In this study, we compare the performance of the relatively new method of Optical Projection Tomography (OPT) to the well-established technique of Optical Coherence Tomography (OCT) to assess murine embryonic development at three stages, 9.5, 11.5, and 13.5 days post conception. While both methods can provide spatial resolution at the micrometer scale, OPT can provide superior imaging depth compared to OCT. However, OPT requires samples to be fixed, placed in an immobilization media such as agar, and cleared before imaging. Because OCT does not require fixing ...

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    19. Live dynamic imaging and analysis of developmental cardiac defects in mouse models with optical coherence tomography

      Live dynamic imaging and analysis of developmental cardiac defects in mouse models with optical coherence tomography

      Understanding mouse embryonic development is an invaluable resource for our interpretation of normal human embryology and congenital defects. Our research focuses on developing methods for live imaging and dynamic characterization of early embryonic development in mouse models of human diseases. Using multidisciplinary methods: optical coherence tomography (OCT), live mouse embryo manipulations and static embryo culture, molecular biology, advanced image processing and computational modeling we aim to understand developmental processes. We have developed an OCT based approach to image live early mouse embryos (E8.5 – E9.5) cultured on an imaging stage and visualize developmental events with a spatial resolution of ...

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    20. Investigating the correlation between white matter and microvasculature changes in aging using large scale optical coherence tomography and confocal fluorescence imaging combined with tissue sectioning

      Investigating the correlation between white matter and microvasculature changes in aging using large scale optical coherence tomography and confocal fluorescence imaging combined with tissue sectioning

      Here, we present a serial OCT/confocal scanner for histological study of the mouse brain. Three axis linear stages combined with a sectioning vibratome allows to cut thru the entire biological tissue and to image every section at a microscopic resolution. After acquisition, each OCT volume and confocal image is re-stitched with adjacent acquisitions to obtain a reconstructed, digital volume of the imaged tissue. This imaging platform was used to investigate correlations between white matter and microvasculature changes in aging mice. Three age groups were used in this study (4, 12, 24 months). At sacrifice, mice were transcardially perfused with ...

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    21. Feature Of The Week 02/22/15: Case Western Reserve University Demostrates Using OCT to Rapidly Phenotype and Quantify Congenital Heart Defects Associated with Prenatal Alcohol Exposure

      Feature Of The Week 02/22/15:  Case Western Reserve University Demostrates Using OCT to Rapidly Phenotype and Quantify Congenital Heart Defects Associated with Prenatal Alcohol Exposure

      The most commonly used method to analyze congenital heart defects involves serial sectioning and histology. However, this is often a time-consuming process where the quantification of cardiac defects can be difficult due to problems with accurate section registration. Here we demonstrate the advantages of using optical coherence tomography, a comparatively new and rising technology, to phenotype avian embryo hearts in a model of Fetal Alcohol Syndrome where a binge-like quantity of alcohol/ethanol was introduced at gastrulation. The rapid, consistent imaging protocols allowed for the immediate identification of cardiac anomalies, including ventricular septal defects and misaligned/missing vessels. Interventricular septum ...

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    22. Algorithms for improved 3-D reconstruction of live mammalian embryo vasculature from optical coherence tomography data

      Algorithms for improved 3-D reconstruction of live mammalian embryo vasculature from optical coherence tomography data

      Background: Robust reconstructions of the three-dimensional network of blood vessels in developing embryos imaged by optical coherence tomography (OCT) are needed for quantifying the longitudinal development of vascular networks in live mammalian embryos, in support of developmental cardiovascular research. Past computational methods [such as speckle variance (SV)] have demonstrated the feasibility of vascular reconstruction, but multiple challenges remain including: the presence of vessel structures at multiple spatial scales, thin blood vessels with weak flow, and artifacts resulting from bulk tissue motion (BTM). Methods: In order to overcome these challenges, this paper introduces a robust and scalable reconstruction algorithm based on ...

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    23. Scientists Identify Genetic Cues for a Big Heart

      Scientists Identify Genetic Cues for a Big Heart

      Bigger isn’t always better, even when it comes to the body’s most vital organs. An enlarged or thickened cardiac muscle can actually force the heart to work harder to pump blood throughout the body, weakening the organ until it eventually wears out. Despite the disastrous consequences of oversized organs, researchers have just begun to uncover the circuitry of signals that govern growth. What they do know comes in large part from genes of the tiny fruit fly, Drosophila melanogaster. Over the years, biologists have deleted or suppressed tens of thousands of genes in the fly genome, aptly naming ...

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    24. Swept source optical coherence tomography Gabor fusion splicing technique for microscopy of thick samples using a deformable mirror

      Swept source optical coherence tomography Gabor fusion splicing technique for microscopy of thick samples using a deformable mirror

      We present a swept source optical coherence tomography (OCT) system at 1060 nm equipped with a wavefront sensor at 830 nm and a deformable mirror in a closed-loop adaptive optics (AO) system. Due to the AO correction, the confocal profile of the interface optics becomes narrower than the OCT axial range, restricting the part of the B-scan (cross section) with good contrast. By actuating on the deformable mirror, the depth of the focus is changed and the system is used to demonstrate Gabor filtering in order to produce B-scan OCT images with enhanced sensitivity throughout the axial range from a ...

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    49-72 of 237 « 1 2 3 4 5 6 7 8 9 10 »
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