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1.
Bull Math Biol ; 78(5): 859-78, 2016 05.
Artículo en Inglés | MEDLINE | ID: mdl-27125657

RESUMEN

Determining the cellular basis of brain growth is an important problem in developmental neurobiology. In the mammalian brain, the cerebellum is particularly amenable to studies of growth because it contains only a few cell types, including the granule cells, which are the most numerous neuronal subtype. Furthermore, in the mouse cerebellum granule cells are generated from granule cell precursors (gcps) in the external granule layer (EGL), from 1 day before birth until about 2 weeks of age. The complexity of the underlying cellular processes (multiple cell behaviors, three spatial dimensions, time-dependent changes) requires a quantitative framework to be fully understood. In this paper, a differential equation-based model is presented, which can be used to estimate temporal changes in granule cell numbers in the EGL. The model includes the proliferation of gcps and their differentiation into granule cells, as well as the process by which granule cells leave the EGL. Parameters describing these biological processes were derived from fitting the model to histological data. This mathematical model should be useful for understanding altered gcp and granule cell behaviors in mouse mutants with abnormal cerebellar development and cerebellar cancers.


Asunto(s)
Cerebelo/citología , Cerebelo/crecimiento & desarrollo , Neuronas/citología , Algoritmos , Animales , Animales Recién Nacidos , Diferenciación Celular , Cerebelo/embriología , Simulación por Computador , Conceptos Matemáticos , Ratones , Ratones Mutantes Neurológicos , Modelos Neurológicos , Células-Madre Neurales/citología , Neuronas/clasificación
2.
Ultrason Imaging ; 38(1): 32-43, 2016 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25925675

RESUMEN

This paper presents an adaptive synthetic-focusing scheme that, when applied to photoacoustic (PA) data acquired using an annular array, improves focusing across a greater imaging depth and enhances spatial resolution. The imaging system was based on a 40-MHz, 5-element, annular-array transducer with a focal length of 12 mm and an 800-µm diameter hole through its central element to facilitate coaxial delivery of 532-nm laser. The transducer was raster-scanned to facilitate 3D acquisition of co-registered ultrasound and PA image data. Three synthetic-focusing schemes were compared for obtaining PA A-lines for each scan location: delay-and-sum (DAS), DAS weighted with a coherence factor (DAS + CF), and DAS weighted with a sign-coherence factor (DAS + SCF). Bench-top experiments that used an 80-µm hair were performed to assess the enhancement provided by the two coherence-based schemes. Both coherence-based schemes increased the signal-to-noise ratio by approximately 10 dB. When processed using the DAS-only scheme, the lateral dimension of the hair in a PA image with 20 dB dynamic range was between 300 µm and 1 mm for imaging depth ranging from 8 to 20 mm. In comparison, the DAS + CF scheme resulted in a lateral dimension of 200 to 450 µm over the same range. The DAS + SCF synthetic focusing further improved the smallest-resolvable dimension, which was between 150 and 400 µm over the same range of imaging depth. When used on PA data obtained from a 12-day-old mouse embryo, the DAS + SCF processing improved visualization of neurovasculature.


Asunto(s)
Interpretación de Imagen Asistida por Computador/métodos , Técnicas Fotoacústicas/métodos , Procesamiento de Señales Asistido por Computador , Transductores , Animales , Desarrollo Embrionario , Diseño de Equipo , Femenino , Cabello/diagnóstico por imagen , Ratones , Fantasmas de Imagen , Embarazo , Sensibilidad y Especificidad , Relación Señal-Ruido , Ultrasonografía
3.
Neuroimage ; 114: 303-10, 2015 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-25869862

RESUMEN

A prominent feature of the developing mammalian brain is the widespread migration of neural progenitor (NP) cells during embryogenesis. A striking example is provided by NP cells born in the ventral forebrain of mid-gestation stage mice, which subsequently migrate long distances to their final positions in the cortex and olfactory bulb. Previous studies have used two-dimensional histological methods, making it difficult to analyze three-dimensional (3D) migration patterns. Unlike histology, magnetic resonance microimaging (micro-MRI) is a non-destructive, quantitative and inherently 3D imaging method for analyzing mouse embryos. To allow mapping of migrating NP cells with micro-MRI, cells were labeled in situ in the medial (MGE) and lateral (LGE) ganglionic eminences, using targeted in utero ultrasound-guided injection of micron-sized particles of iron-oxide (MPIO). Ex vivo micro-MRI and histology were then performed 5-6days after injection, demonstrating that the MPIO had magnetically labeled the migrating NP populations, which enabled 3D visualization and automated segmentation of the labeled cells. This approach was used to analyze the distinct patterns of migration from the MGE and LGE, and to construct rostral-caudal migration maps from each progenitor region. Furthermore, abnormal migratory phenotypes were observed in Nkx2.1(-/-) embryos, most notably a significant increase in cortical neurons derived from the Nkx2.1(-/-) LGE. Taken together, these results demonstrate that MPIO labeling and micro-MRI provide an efficient and powerful approach for analyzing 3D cell migration patterns in the normal and mutant mouse embryonic brain.


Asunto(s)
Encéfalo/embriología , Movimiento Celular , Imagen por Resonancia Magnética/métodos , Neuronas/fisiología , Animales , Encéfalo/anatomía & histología , Femenino , Imagenología Tridimensional , Ratones , Ratones Endogámicos ICR , Neuronas/citología
4.
Circ Res ; 110(7): 938-47, 2012 Mar 30.
Artículo en Inglés | MEDLINE | ID: mdl-22374133

RESUMEN

RATIONALE: The formation and maintenance of a functional vasculature is essential for normal embryonic development, and genetic changes that affect the vasculature underlie pathogenesis in many human diseases. In vivo imaging in mouse models is required to understand the full complexity of mammalian vascular formation, which is a dynamic and 3-dimensional process. Optical microscopy of genetically expressed fluorescent reporter proteins offers high resolution but limited depth of penetration in vivo. Conversely, there are a plethora of molecular probes for alternative in vivo vascular imaging modalities, but few options for genetic control of contrast enhancement. OBJECTIVE: To develop a reporter system for multimodal imaging of genetic processes involved in mammalian vascular biology. METHODS AND RESULTS: To approach this problem, we developed an optimal tagging system based on Biotag-BirA technology. In the resulting Biotag reporter system, coexpression of 2 interacting proteins results in biotin labeling of cell membranes, thus enabling multimodal imaging with "avidinated" probes. To assess this approach for in vivo imaging, we generated transgenic mice that expressed the Biotag-BirA transgene from a minimal Tie2 promoter. A variety of imaging methods were used to show the utility of this approach for quantitative analysis in embryonic and adult models of vascular development, using intravascular injection of avidinated probes for near infrared, ultrasound, and magnetic resonance imaging. CONCLUSIONS: The present results demonstrate the versatility of the Biotag system for studies of vascular biology in genetically engineered mice, providing a robust approach for multimodal in vivo imaging of genetic processes in the vasculature.


Asunto(s)
Vasos Sanguíneos/citología , Vasos Sanguíneos/embriología , Embrión de Mamíferos/irrigación sanguínea , Embrión de Mamíferos/embriología , Desarrollo Embrionario/genética , Imagen por Resonancia Magnética/métodos , Animales , Biomarcadores/metabolismo , Biotecnología/métodos , Biotina/genética , Biotina/metabolismo , Vasos Sanguíneos/metabolismo , Embrión de Mamíferos/metabolismo , Femenino , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Células HEK293 , Humanos , Ratones , Ratones Transgénicos , Modelos Animales , Molécula-1 de Adhesión Celular Endotelial de Plaqueta/genética , Molécula-1 de Adhesión Celular Endotelial de Plaqueta/metabolismo , Embarazo , Proteínas Tirosina Quinasas Receptoras/genética , Proteínas Tirosina Quinasas Receptoras/metabolismo , Receptor TIE-2
5.
Curr Protoc ; 4(9): e1116, 2024 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-39222027

RESUMEN

The mouse is the mammalian model of choice for investigating cardiovascular biology, given our ability to manipulate it by genetic, pharmacologic, mechanical, and environmental means. Imaging is an important approach to phenotyping both function and structure of cardiac and vascular components. This review details commonly used imaging approaches, with a focus on echocardiography and magnetic resonance imaging, with brief overviews of other imaging modalities. In this update, we also emphasize the importance of rigor and reproducibility in imaging approaches, experimental design, and documentation. Finally, we briefly outline emerging imaging approaches but caution that reliability and validity data may be lacking. © 2024 Wiley Periodicals LLC.


Asunto(s)
Imagen por Resonancia Magnética , Animales , Ratones , Imagen por Resonancia Magnética/métodos , Ecocardiografía/métodos , Sistema Cardiovascular/diagnóstico por imagen
6.
ACS Biomater Sci Eng ; 10(5): 3425-3437, 2024 05 13.
Artículo en Inglés | MEDLINE | ID: mdl-38622760

RESUMEN

Triple-negative breast cancer (TNBC) lacks expressed protein targets, making therapy development challenging. Hydrogels offer a promising new route in this regard by improving the chemotherapeutic efficacy through increased solubility and sustained release. Moreover, subcutaneous hydrogel administration reduces patient burden by requiring less therapy and shorter treatment times. We recently established the design principles for the supramolecular assembly of single-domain coiled-coils into hydrogels. Using a modified computational design algorithm, we designed Q8, a hydrogel with rapid assembly for faster therapeutic hydrogel preparation. Q8 encapsulates and releases doxorubicin (Dox), enabling localized sustained release via subcutaneous injection. Remarkably, a single subcutaneous injection of Dox-laden Q8 (Q8•Dox) significantly suppresses tumors within just 1 week. This work showcases the bottom-up engineering of a fully protein-based drug delivery vehicle for improved TBNC treatment via noninvasive localized therapy.


Asunto(s)
Preparaciones de Acción Retardada , Doxorrubicina , Hidrogeles , Neoplasias de la Mama Triple Negativas , Doxorrubicina/farmacología , Doxorrubicina/administración & dosificación , Doxorrubicina/química , Doxorrubicina/uso terapéutico , Hidrogeles/química , Neoplasias de la Mama Triple Negativas/tratamiento farmacológico , Neoplasias de la Mama Triple Negativas/patología , Femenino , Humanos , Animales , Preparaciones de Acción Retardada/química , Línea Celular Tumoral , Ingeniería de Proteínas , Ratones , Liberación de Fármacos , Antibióticos Antineoplásicos/administración & dosificación , Antibióticos Antineoplásicos/farmacología , Antibióticos Antineoplásicos/uso terapéutico , Antibióticos Antineoplásicos/química
7.
Biomater Sci ; 12(11): 2951-2959, 2024 May 28.
Artículo en Inglés | MEDLINE | ID: mdl-38656316

RESUMEN

The development of targeted anti-cancer therapeutics offers the potential for increased efficacy of drugs and diagnostics. Utilizing modalities agnostic to tumor type, such as the hypoxic tumor microenvironment (TME), may assist in the development of universal tumor targeting agents. The hypoxia-inducible factor (HIF), in particular HIF1, plays a key role in tumor adaptation to hypoxia, and inhibiting its interaction with p300 has been shown to provide therapeutic potential. Using a multivalent assembled protein (MAP) approach based on the self-assembly of the cartilage oligomeric matrix protein coiled-coil (COMPcc) domain fused to the critical residues of the C-terminal transactivation domain (C-TAD) of the α subunit of HIF1 (HIF1α), we generate HIF1α-MAP (H-MAP). The resulting H-MAP demonstrates picomolar binding affinity to p300, the ability to downregulate hypoxia-inducible genes, and in vivo tumor targeting capability.


Asunto(s)
Subunidad alfa del Factor 1 Inducible por Hipoxia , Ingeniería de Proteínas , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Subunidad alfa del Factor 1 Inducible por Hipoxia/química , Humanos , Animales , Dominios Proteicos , Ratones , Línea Celular Tumoral , Proteína de la Matriz Oligomérica del Cartílago/química , Proteína de la Matriz Oligomérica del Cartílago/metabolismo , Microambiente Tumoral , Proteína p300 Asociada a E1A/metabolismo , Proteína p300 Asociada a E1A/química
8.
ACS Appl Nano Mater ; 6(22): 21245-21257, 2023 Nov 24.
Artículo en Inglés | MEDLINE | ID: mdl-38037605

RESUMEN

Theranostic materials research is experiencing rapid growth driven by the interest in integrating both therapeutic and diagnostic modalities. These materials offer the unique capability to not only provide treatment but also track the progression of a disease. However, to create an ideal theranostic biomaterial without compromising drug encapsulation, diagnostic imaging must be optimized for improved sensitivity and spatial localization. Herein, we create a protein-engineered fluorinated coiled-coil fiber, Q2TFL, capable of improved sensitivity to 19F magnetic resonance spectroscopy (MRS) detection. Leveraging residue-specific noncanonical amino acid incorporation of trifluoroleucine (TFL) into the coiled-coil, Q2, which self-assembles into nanofibers, we generate Q2TFL. We demonstrate that fluorination results in a greater increase in thermostability and 19F magnetic resonance detection compared to the nonfluorinated parent, Q2. Q2TFL also exhibits linear ratiometric 19F MRS thermoresponsiveness, allowing it to act as a temperature probe. Furthermore, we explore the ability of Q2TFL to encapsulate the anti-inflammatory small molecule, curcumin (CCM), and its impact on the coiled-coil structure. Q2TFL also provides hyposignal contrast in 1H MRI, echogenic signal with high-frequency ultrasound and sensitive detection by 19F MRS in vivo illustrating fluorination of coiled-coils for supramolecular assembly and their use with 1H MRI, 19F MRS and high frequency ultrasound as multimodal theranostic agents.

9.
Ultrasound Med Biol ; 49(1): 356-367, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-36283941

RESUMEN

Large-scale international efforts to generate and analyze loss-of-function mutations in each of the approximately 20,000 protein-encoding gene mutations are ongoing using the "knockout" mouse as a model organism. Because one-third of gene knockouts are expected to result in embryonic lethality, it is important to develop non-invasive in utero imaging methods to detect and monitor mutant phenotypes in mouse embryos. We describe the utility of 3-D high-frequency (40-MHz) ultrasound (HFU) for longitudinal in utero imaging of mouse embryos between embryonic days (E) 11.5 and E14.5, which represent critical stages of brain and organ development. Engrailed-1 knockout (En1-ko) mouse embryos and their normal control littermates were imaged with HFU in 3-D, enabling visualization of morphological phenotypes in the developing brains, limbs and heads of the En1-ko embryos. Recently developed deep learning approaches were used to automatically segment the embryonic brain ventricles and bodies from the 3-D HFU images, allowing quantitative volumetric analyses of the En1-ko brain phenotypes. Taken together, these results show great promise for the application of longitudinal 3-D HFU to analyze knockout mouse embryos in utero.


Asunto(s)
Encéfalo , Imagenología Tridimensional , Animales , Ratones , Ratones Noqueados , Ultrasonografía , Imagenología Tridimensional/métodos , Fenotipo , Embrión de Mamíferos/diagnóstico por imagen
10.
J Vis Exp ; (181)2022 03 08.
Artículo en Inglés | MEDLINE | ID: mdl-35343960

RESUMEN

Metastasis is a complex process, requiring cells to overcome barriers that are only incompletely modeled by in vitro assays. A systematic workflow was established using robust, reproducible in vivo models and standardized methods to identify novel players in melanoma metastasis. This approach allows for data inference at specific experimental stages to precisely characterize a gene's role in metastasis. Models are established by introducing genetically modified melanoma cells via intracardiac, intradermal, or subcutaneous injections into mice, followed by monitoring with serial in vivo imaging. Once preestablished endpoints are reached, primary tumors and/or metastases-bearing organs are harvested and processed for various analyses. Tumor cells can be sorted and subjected to any of several 'omics' platforms, including single-cell RNA sequencing. Organs undergo imaging and immunohistopathological analyses to quantify the overall burden of metastases and map their specific anatomic location. This optimized pipeline, including standardized protocols for engraftment, monitoring, tissue harvesting, processing, and analysis, can be adopted for patient-derived, short-term cultures and established human and murine cell lines of various solid cancer types.


Asunto(s)
Melanoma , Animales , Línea Celular , Humanos , Melanoma/patología , Ratones , Metástasis de la Neoplasia
11.
Artículo en Inglés | MEDLINE | ID: mdl-32763851

RESUMEN

The rodent heart is frequently used to study human cardiovascular disease (CVD). Although advanced cardiovascular ultrasound imaging methods are available for human clinical practice, application of these techniques to small animals remains limited due to the temporal and spatial-resolution demands. Here, an ultrasound vector-flow workflow is demonstrated that enables visualization and quantification of the complex hemodynamics within the mouse heart. Wild type (WT) and fibroblast growth factor homologous factor 2 (FHF2)-deficient mice (Fhf2 KO/Y ), which present with hyperthermia-induced ECG abnormalities highly reminiscent of Brugada syndrome, were used as a mouse model of human CVD. An 18-MHz linear array was used to acquire high-speed (30 kHz), plane-wave data of the left ventricle (LV) while increasing core body temperature up to 41.5 °C. Hexplex (i.e., six output) processing of the raw data sets produced the output of vector-flow estimates (magnitude and phase); B-mode and color-Doppler images; Doppler spectrograms; and local time histories of vorticity and pericardium motion. Fhf2 WT/Y mice had repeatable beat-to-beat cardiac function, including vortex formation during diastole, at all temperatures. In contrast, Fhf2 KO/Y mice displayed dyssynchronous contractile motion that disrupted normal inflow vortex formation and impaired LV filling as temperature rose. The hexplex processing approach demonstrates the ability to visualize and quantify the interplay between hemodynamic and mechanical function in a mouse model of human CVD.


Asunto(s)
Ventrículos Cardíacos , Hemodinámica , Animales , Velocidad del Flujo Sanguíneo , Diástole , Ventrículos Cardíacos/diagnóstico por imagen , Ratones , Pericardio , Ultrasonografía , Función Ventricular Izquierda
12.
Artículo en Inglés | MEDLINE | ID: mdl-33755564

RESUMEN

Segmentation and mutant classification of high-frequency ultrasound (HFU) mouse embryo brain ventricle (BV) and body images can provide valuable information for developmental biologists. However, manual segmentation and identification of BV and body requires substantial time and expertise. This article proposes an accurate, efficient and explainable deep learning pipeline for automatic segmentation and classification of the BV and body. For segmentation, a two-stage framework is implemented. The first stage produces a low-resolution segmentation map, which is then used to crop a region of interest (ROI) around the target object and serve as the probability map of the autocontext input for the second-stage fine-resolution refinement network. The segmentation then becomes tractable on high-resolution 3-D images without time-consuming sliding windows. The proposed segmentation method significantly reduces inference time (102.36-0.09 s/volume ≈ 1000× faster) while maintaining high accuracy comparable to previous sliding-window approaches. Based on the BV and body segmentation map, a volumetric convolutional neural network (CNN) is trained to perform a mutant classification task. Through backpropagating the gradients of the predictions to the input BV and body segmentation map, the trained classifier is found to largely focus on the region where the Engrailed-1 (En1) mutation phenotype is known to manifest itself. This suggests that gradient backpropagation of deep learning classifiers may provide a powerful tool for automatically detecting unknown phenotypes associated with a known genetic mutation.


Asunto(s)
Aprendizaje Profundo , Imagenología Tridimensional , Animales , Procesamiento de Imagen Asistido por Computador , Ratones , Redes Neurales de la Computación , Ultrasonografía
13.
Proc IEEE Int Symp Biomed Imaging ; 2020: 122-126, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33381278

RESUMEN

The segmentation of the brain ventricle (BV) and body in embryonic mice high-frequency ultrasound (HFU) volumes can provide useful information for biological researchers. However, manual segmentation of the BV and body requires substantial time and expertise. This work proposes a novel deep learning based end-to-end auto-context refinement framework, consisting of two stages. The first stage produces a low resolution segmentation of the BV and body simultaneously. The resulting probability map for each object (BV or body) is then used to crop a region of interest (ROI) around the target object in both the original image and the probability map to provide context to the refinement segmentation network. Joint training of the two stages provides significant improvement in Dice Similarity Coefficient (DSC) over using only the first stage (0.818 to 0.906 for the BV, and 0.919 to 0.934 for the body). The proposed method significantly reduces the inference time (102.36 to 0.09 s/volume ≈1000x faster) while slightly improves the segmentation accuracy over the previous methods using slide-window approaches.

14.
Proc IEEE Int Symp Biomed Imaging ; 2018: 635-639, 2018 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-30906506

RESUMEN

This paper presents a fully automatic segmentation system for whole-body high-frequency ultrasound (HFU) images of mouse embryos that can simultaneously segment the body contour and the brain ventricles (BVs). Our system first locates a region of interest (ROI), which covers the interior of the uterus, by sub-surface analysis. Then, it segments the ROI into BVs, the body, the amniotic fluid, and the uterine wall, using nested graph cut. Simultaneously multilevel thresholding is applied to the whole-body image to propose candidate BV components. These candidates are further truncated by the embryo mask (body+BVs) to refine the BV candidates. Finally, subsets of all candidate BVs are compared with pre-trained spring models describing valid BV structures, to identify true BV components. The system can segment the body accurately in most cases based on visual inspection, and achieves average Dice similarity coefficient of 0.8924 ± 0.043 for the BVs on 36 HFU image volumes.

15.
Artículo en Inglés | MEDLINE | ID: mdl-30911672

RESUMEN

Volumetric analysis of brain ventricle (BV) structure is a key tool in the study of central nervous system development in embryonic mice. High-frequency ultrasound (HFU) is the only non-invasive, real-time modality available for rapid volumetric imaging of embryos in utero. However, manual segmentation of the BV from HFU volumes is tedious, time-consuming, and requires specialized expertise. In this paper, we propose a novel deep learning based BV segmentation system for whole-body HFU images of mouse embryos. Our fully automated system consists of two modules: localization and segmentation. It first applies a volumetric convolutional neural network on a 3D sliding window over the entire volume to identify a 3D bounding box containing the entire BV. It then employs a fully convolutional network to segment the detected bounding box into BV and background. The system achieves a Dice Similarity Coefficient (DSC) of 0.8956 for BV segmentation on an unseen 111 HFU volume test set surpassing the previous state-of-the-art method (DSC of 0.7119) by a margin of 25%.

16.
Mol Imaging Biol ; 19(2): 203-214, 2017 04.
Artículo en Inglés | MEDLINE | ID: mdl-27677887

RESUMEN

PURPOSE: In this study, we evaluated a genetic approach for in vivo multimodal molecular imaging of vasculature in a mouse model of melanoma. PROCEDURES: We used a novel transgenic mouse, Ts-Biotag, that genetically biotinylates vascular endothelial cells. After inoculating these mice with B16 melanoma cells, we selectively targeted endothelial cells with (strept)avidinated contrast agents to achieve multimodal contrast enhancement of Tie2-expressing blood vessels during tumor progression. RESULTS: This genetic targeting system provided selective labeling of tumor vasculature and showed in vivo binding of avidinated probes with high specificity and sensitivity using microscopy, near infrared, ultrasound, and magnetic resonance imaging. We further demonstrated the feasibility of conducting longitudinal three-dimensional (3D) targeted imaging studies to dynamically assess changes in vascular Tie2 from early to advanced tumor stages. CONCLUSIONS: Our results validated the Ts-Biotag mouse as a multimodal targeted imaging system with the potential to provide spatio-temporal information about dynamic changes in vasculature during tumor progression.


Asunto(s)
Melanoma Experimental/irrigación sanguínea , Imagen Molecular/métodos , Imagen Multimodal/métodos , Animales , Biotinilación , Proliferación Celular , Medios de Contraste/química , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Células Endoteliales/metabolismo , Células Endoteliales/patología , Expresión Génica , Cinética , Melanoma Experimental/patología , Ratones Endogámicos C57BL , Ratones Transgénicos , Receptor TIE-2/metabolismo , Transgenes , Ultrasonografía
17.
Sci Rep ; 7(1): 16658, 2017 11 30.
Artículo en Inglés | MEDLINE | ID: mdl-29192281

RESUMEN

Real-time imaging of the embryonic murine cardiovascular system is challenging due to the small size of the mouse embryo and rapid heart rate. High-frequency, linear-array ultrasound systems designed for small-animal imaging provide high-frame-rate and Doppler modes but are limited in regards to the field of view that can be imaged at fine-temporal and -spatial resolution. Here, a plane-wave imaging method was used to obtain high-speed image data from in utero mouse embryos and multi-angle, vector-flow algorithms were applied to the data to provide information on blood flow patterns in major organs. An 18-MHz linear array was used to acquire plane-wave data at absolute frame rates ≥10 kHz using a set of fixed transmission angles. After beamforming, vector-flow processing and image compounding, effective frame rates were on the order of 2 kHz. Data were acquired from the embryonic liver, heart and umbilical cord. Vector-flow results clearly revealed the complex nature of blood-flow patterns in the embryo with fine-temporal and -spatial resolution.


Asunto(s)
Embrión de Mamíferos/diagnóstico por imagen , Ultrasonografía/métodos , Animales , Ratones , Fantasmas de Imagen , Ultrasonografía Doppler/métodos
18.
Circ Res ; 92(2): 133-5, 2003 Feb 07.
Artículo en Inglés | MEDLINE | ID: mdl-12574139

RESUMEN

When cardiac function and blood flow are first established are fundamental questions in mammalian embryogenesis. The earliest erythroblasts arise in yolk sac blood islands and subsequently enter the embryo proper to initiate circulation. Embryos staged 0 to 30 somites (S) were examined in utero with 40- to 50-MHz ultrasound biomicroscopy (UBM)-Doppler, to determine onset of embryonic heartbeat and blood flow and to characterize basic physiology of the very early mouse embryonic circulation. A heartbeat was first detected at 5 S, and blood vascular flow at 7 S. Heart rate, peak arterial velocity, and velocity-time integral showed progressive increases that indicated a dramatically increasing cardiac output from even the earliest stages. In situ hybridization revealed an onset of the heartbeat coincident with the appearance of yolk sac-derived erythroblasts in the embryo proper at 5 S. Early maturation of the circulation follows a tightly coordinated program.


Asunto(s)
Eritroblastos/citología , Corazón/embriología , Corazón/fisiología , Miocardio/citología , Organogénesis/fisiología , Animales , Aorta/embriología , Aorta/fisiología , Circulación Sanguínea/fisiología , Velocidad del Flujo Sanguíneo/fisiología , Movimiento Celular/fisiología , Embrión de Mamíferos/irrigación sanguínea , Frecuencia Cardíaca Fetal , Hibridación in Situ , Ratones , Microscopía Acústica/métodos , Factores de Tiempo , Ultrasonografía Doppler , Ultrasonografía Prenatal
19.
Circ Res ; 95(1): 92-9, 2004 Jul 09.
Artículo en Inglés | MEDLINE | ID: mdl-15166096

RESUMEN

Gene targeting in the mouse has become a standard approach, yielding important new insights into the genetic factors underlying cardiovascular development and disease. However, we still have very limited understanding of how mutations affect developing cardiovascular function, and few studies have been performed to measure altered physiological parameters in mouse mutant embryos. Indeed, although in utero lethality due to embryonic heart failure is one of the most common results of gene targeting experiments in the mouse, the underlying physiological mechanisms responsible for embryonic demise remain elusive. Using in utero ultrasound biomicroscopy (UBM), we studied embryonic day (E) 10.5 to 14.5 NFATc1-/- embryos and control littermates. NFATc1-/- mice, which lack outflow valves, die at mid-late gestation from presumed defects in forward blood flow with resultant heart failure. UBM showed increasing abnormal regurgitant flow in the aorta and extending into the embryonal-placental circulation, which was evident after E12.5 when outflow valves normally first develop. Reduced NFATc1-/- net volume flow and diastolic dysfunction contributed to heart failure, but contractile function remained unexpectedly normal. Among 107 NFATc1-/- embryos imaged, only 2 were observed to be in acute decline with progressive bradyarrhythmia, indicating that heart failure occurs rapidly in individual NFATc1-/- embryos. This study is among the first linking a specific physiological phenotype with a defined genotype, and demonstrates that NFATc1-/- embryonic heart failure is a complex phenomenon not simply attributable to contractile dysfunction.


Asunto(s)
Gasto Cardíaco Bajo/etiología , Proteínas de Unión al ADN/genética , Enfermedades Fetales/etiología , Proteínas Nucleares/genética , Factores de Transcripción/genética , Animales , Circulación Sanguínea , Gasto Cardíaco Bajo/diagnóstico por imagen , Gasto Cardíaco Bajo/fisiopatología , Embrión de Mamíferos/diagnóstico por imagen , Embrión de Mamíferos/fisiopatología , Femenino , Enfermedades Fetales/diagnóstico por imagen , Enfermedades Fetales/fisiopatología , Corazón/fisiopatología , Ratones , Ratones Noqueados , Microscopía Acústica , Contracción Miocárdica , Factores de Transcripción NFATC , Circulación Placentaria , Embarazo
20.
Ultrasound Med Biol ; 32(11): 1631-7, 2006 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-17112949

RESUMEN

Ultrasound biomicroscopy (UBM) has emerged as an important in vivo imaging approach for analyzing normal and genetically engineered mouse embryos. Current UBM systems use fixed-focus transducers, which are limited in depth-of-focus. Depending on the gestational age of the embryo, regions-of-interest in the image can extend well beyond the depth-of-focus for a fixed-focus transducer. This shortcoming makes it particularly problematic to analyze 3-D data sets and to generate accurate volumetric renderings of the mouse embryonic anatomy. To address this problem, we have developed a five-element, 40-MHz annular array transducer and a computer-controlled system to acquire and reconstruct fixed- and array-focused images of mouse embryos. Both qualitative and quantitative comparisons showed significant improvement with array-focusing, including an increase of 3 to 9 dB in signal-to-noise ratio and an increase of at least 2.5 mm in depth-of-focus. Volumetric-rendered images of brain ventricles demonstrated the clear superiority of array-focusing for 3-D analysis of mouse embryonic anatomy.


Asunto(s)
Embrión de Mamíferos/diagnóstico por imagen , Ultrasonografía Prenatal/métodos , Animales , Ventrículos Cerebrales/diagnóstico por imagen , Ventrículos Cerebrales/embriología , Procesamiento de Imagen Asistido por Computador , Imagenología Tridimensional/métodos , Ratones , Microscopía Acústica/instrumentación , Microscopía Acústica/métodos , Transductores , Ultrasonografía Prenatal/instrumentación
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