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High-resolution Imaging (high-resolution + imaging)
Selected AbstractsHigh-resolution imaging demonstrates dynein-based vesicular transport of activated trk receptorsDEVELOPMENTAL NEUROBIOLOGY, Issue 4 2002Anita Bhattacharyya Abstract Target-derived neurotrophins signal from nerve endings to the cell body to influence cellular and nuclear responses. The retrograde signal is conveyed by neurotrophin receptors (Trks) themselves. To accomplish this, activated Trks may physically relocalize from nerve endings to the cell bodies. However, alternative signaling mechanisms may also be used. To identify the vehicle wherein the activated Trks are located and transported, and to identify associated motor proteins that would facilitate transport, we use activation-state specific antibodies in concert with immunoelectron microscopy and deconvolution microscopy. We show that the activated Trks within rat sciatic nerve axons are preferentially localized to coated and uncoated vesicles. These vesicles are moving in a retrograde direction and so accumulate distal to a ligation site. The P-Trk containing vesicles, in turn, colocalize with dynein components, and not with kinesins. Collectively, these results indicate activated Trk within axons travel in vesicles and dynein is the motor that drives these vesicles towards the cell bodies. © 2002 Wiley Periodicals, Inc. J Neurobiol 51: 302,312, 2002 [source] Dynamic T1-weighted monitoring of vascularization in human carcinoma heterotransplants by magnetic resonance imaging,INTERNATIONAL JOURNAL OF CANCER, Issue 1 2003Fabian Kiessling Abstract Studies on tumor angiogenesis and antiangiogenic therapies are commonly performed with tumor heterotransplants in nude mice. To monitor therapeutic effects, improved noninvasive analyses of functional data are required, in addition to the assessment of tumor volume and histology. Here, we report on sequential monitoring of vascularization of human squamous cell carcinomas growing as heterotransplants in nude mice using MRI. Using a custom-developed animal coil in a conventional whole-body 1.5 T MRI scanner, dynamic T1w sequences were recorded after i.v. injection of Gd-DTPA in tumors grown for 17, 21, 25, 29 and 33 days. Amplitude and the exchange rate constant (kep) were calculated according to a 2-compartment model, discriminating intravascular and interstitial spaces, and correlated with tumor size and histology. High-resolution imaging of small heterotransplants from 100 to 1,000 mm3 was achieved, clearly discriminating vital and necrotic areas. Preceding the development of necroses, which were hyperintense in T2w images and confirmed with histology, a local decrease of amplitude and kep values was observed. Significantly higher amplitudes were found in tumor periphery than in central parts, correlating well with the vascular pattern obtained by immunocytochemistry. Tumor size correlated negatively with amplitude, probably as a result of increasing necrotic areas, whereas the reason for the observed increase of kep value with tumor size remains unclear. These data demonstrate that dynamic MRI is an excellent method for noninvasive assessment of tumor vascularization in small animals using a clinical whole-body scanner with little technical modifications. This technique provides functional data characterizing essential features of tumor biology and is thus appropriate for monitoring antiangiogenic therapies. © 2002 Wiley-Liss, Inc. [source] High-resolution imaging using integrated optical systemsINTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY, Issue 2 2004S. Prasad Abstract Certain optical aberrations, such as defocus, can significantly degrade the signal collected by an imaging system, producing images with low resolution. In images with depth-dependent detail, such degradations are difficult to remove due to their inherent spatially varying nature. In 1995, Dowski and Cathey introduced the concept of wavefront coding to extend the depth of field. They showed that wavefront coding and decoding enables quality control of such images using integrated optical-digital imaging systems. With wavefront coding, a high-resolution image can be efficiently obtained without the need to resort to expensive algorithms for spatially varying restoration. In this article, we discuss a novel and effective multiple-design-parameter approach for optimizing the processes of encoding and decoding the wavefront phase in integrated optical-digital imaging systems. Our approach involves the use of information metrics, such as the Strehl ratio and Fisher information, for determining the optimal pupil-phase distribution for which the resulting image is insensitive to certain aberrations, such as focus errors. The effectiveness of this approach is illustrated with a number of numerical simulation experiments, and applications to the development of iris recognition systems with high-resolution capabilities are briefly discussed. © 2004 Wiley Periodicals, Inc. Int J Imaging Syst Technol 14, 67,74, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.20009 [source] High-resolution imaging of progressive articular cartilage degenerationJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2006Samuel B. Adams Jr Abstract The objective of this study was to develop and verify a new technique for monitoring the progression of osteoarthritis (OA) by combining a rat model with the imaging modality optical coherence tomography (OCT). Time-sequential, in vivo, OCT imaging was performed on the left femoral condyles of 12 Wistar rats following sodium,iodoacetic acid-induced OA progression. The right femoral condyles (untreated) were also imaged and served as controls. Imaging was performed on days 0, 10, 20, 30, and 60 with an OCT system capable of acquiring images at four frames per second and an axial resolution of 5 µm. Progressive changes were analyzed using an OA scoring system. OCT successfully identified progressive cartilage degeneration as well as alteration of the cartilage/bone interface. Significant changes to both of these structures were observed in the sodium,iodoacetic acid-injected condyles. Structural changes detected with OCT were confirmed histologically. OCT in combination with a well-known model used in arthritis research represents a powerful tool for following degenerative joint disease progression in a given animal by detecting changes to the cartilage/bone interface and articular cartilage. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res [source] High-resolution imaging and proteomics of peptide fragments by TOF-SIMSPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 8 2010Håkan Nygren Abstract Thyroglobulin is an iodinated glycoprotein (m.w. 660,kD) required for the storage and formation of thyroid hormone. Thyroglobulin was digested by trypsin in distilled water and the resulting peptides were identified by TOF-secondary ion mass spectrometry, using TFA as a matrix to catalyze the ionization of the peptides. Cryostate sections of pig thyroid glands were incubated with trypsin in distilled water, followed by deposition of TFA. The sections were analyzed with TOF-secondary ion mass spectrometry, and the peptides formed were identified through comparison with the peptides of the thyroglobulin reference sample. The thyroglobulin fragments were localized in the thyroid follicle cells with a spatial resolution of 3 microns, a mass resolution m/,m of >6000 and a mass accuracy of <60,ppm. The thyroglobulin was found localized heterogeneously in the follicle cells. The heterogeneity may be due to thyroglobulin synthesis, uptake and degradation or globules representing insoluble polymers of thyroglobulin considered to be a mechanism for storing hormone at high concentrations. [source] The human hippocampus at 7 T,In vivo MRIHIPPOCAMPUS, Issue 1 2009Jens M. Theysohn Abstract The human hippocampus plays a central role in various neuropsychiatric disorders, such as temporal lobe epilepsy (TLE), Alzheimer's dementia, mild cognitive impairment, and schizophrenia. Its volume, morphology, inner structure, and function are of scientific and clinical interest. Magnetic resonance (MR) imaging is a widely employed tool in neuroradiological workup regarding changes in brain anatomy, (sub-) volumes, and cerebral function including the hippocampus. Gain in intrinsic MR signal provided by higher field strength scanners and concomitant improvements in spatial resolution seem highly valuable. An examination protocol permitting complete, high-resolution imaging of the human hippocampus at 7 T was implemented. Coronal proton density, T2, T2*, and fluid-attenuated inversion recovery contrasts were acquired as well as an isotropic 3D magnetization-prepared rapid acquisition gradient-echo (500 ,m isotropic voxel dimension, noninterpolated). Observance of energy deposition restrictions within acceptable scan times remained challenging in the acquisition of thin, spin-echo-based sections. At the higher resolution enabled by 7 T, demarcation of the hippocampus and some internal features including gray/white matter differentiation and depiction of the hippocampal mantle becomes much more viable when compared with 1.5 T; thus, in the future, this imaging technology might help in the diagnosis of subtle hippocampal changes. © 2008 Wiley-Liss, Inc. [source] Whole-body MR angiography using a novel 32-receiving-channel MR system with surface coil technology: First clinical experienceJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2005Michael Fenchel MD Abstract Purpose To demonstrate the feasibility of detecting atherosclerotic vascular disease using an innovative magnetic resonance angiography (MRA) protocol in combination with a dedicated whole-body MR scanner with new surface coil technology. Materials and Methods A total of 10 volunteers and eight patients with peripheral arterial occlusive disease (PAOD) were examined at 1.5 T. Conventional digital subtraction angiography (DSA) of the symptomatic region was available as a reference standard in all eight patients. Depending on subjects' size, four to five three-dimensional data sets were acquired using an adapted injection protocol. Images were assessed independently by two readers for vascular pathology. Additionally, signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) were measured. Results Whole-body MRA yielded excellent sensitivity and specificity of more than 95% for both readers with high interobserver agreement (k = 0.93). Surface coil signal reception rendered a high SNR (mean 151.28 ± 54.04) and CNR (mean 120.75 ± 46.47). Despite lower SNR and CNR of the cranial and cervical vessels, a two-step injection protocol exhibited less venous superposition and therefore proved to be superior compared to single-bolus injection. Conclusion Our approach provides accurate noninvasive high-resolution imaging of systemic atherosclerotic disease, covering the arterial vasculature from intracranial arteries to distal runoff vessels. The recently introduced MR scanner and coil technology is feasible to significantly increase the performance of whole-body MRA. J. Magn. Reson. Imaging 2005;21:596,603. © 2005 Wiley-Liss, Inc. [source] The potential of current high-resolution imaging-based particle size distribution measurements for crystallization monitoringAICHE JOURNAL, Issue 4 2009P. A. Larsen Abstract High-speed, in situ video microscopy is a promising technology for measuring critical solid-phase properties in suspension crystallization processes. This paper demonstrates the feasibility of high-resolution, video-imaging-based particle size distribution (PSD) measurement by applying image analysis and statistical estimation tools to images from a simulated batch crystallization of an industrial photochemical. The results also demonstrate the ability to monitor important quality parameters, such as the ratio of nuclei mass to seed mass, that cannot be monitored by conventional technologies. General recommendations are given for achieving appropriate sampling conditions to enable effective imaging-based PSD measurement. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Optimized interleaved whole-brain 3D double inversion recovery (DIR) sequence for imaging the neocortexMAGNETIC RESONANCE IN MEDICINE, Issue 6 2004P.A. Boulby Abstract For a substantial number of individuals with neurological disorders, a conventional MRI scan does not reveal any obvious etiology; however, it is believed that abnormalities in the neocortical gray matter (GM) underlie many of these disorders. Attempts to image the neocortex are hindered by its thin, convoluted structure, and the partial volume (PV) effect. Therefore, we developed a 3D version of the double inversion recovery (DIR) sequence that incorporates an optimized interleaved (OIL) strategy to improve efficiency and allow high-quality, high-resolution imaging of GM. Magn Reson Med 51:1181,1186, 2004. © 2004 Wiley-Liss, Inc. [source] High-resolution blood flow velocity measurements in the human fingerMAGNETIC RESONANCE IN MEDICINE, Issue 4 2001M. Klarhöfer Abstract MR phase contrast blood flow velocity measurements in the human index finger were performed with triggered, nontriggered, and cine acquisition schemes. A strong (Gmax = 200 mT/m), small bore (inner diameter 12 cm) gradient system inserted in a whole body 3 Tesla MR scanner allowed high-resolution imaging at short echo times, which decreases partial volume effects and flow artifacts. Arterial blood flow velocities ranging from 4.9,19 cm/sec were measured, while venous blood flow was significantly slower at 1.5,7.1 cm/sec. Taking into account the corresponding vessel diameters ranging from 800 ,m to 1.8 mm, blood flow rates of 3.0,26 ml/min in arteries and 1.2,4.8 ml/min in veins are obtained. The results were compared to ultrasound measurements, resulting in comparable blood flow velocities in the same subjects. Magn Reson Med 45:716,719, 2001. © 2001 Wiley-Liss, Inc. [source] A High-Content, Cell-Based Screen Identifies Micropolyin, A New Inhibitor of Microtubule DynamicsCHEMICAL BIOLOGY & DRUG DESIGN, Issue 6 2009Manu De Rycker High-content cell-based screens provide a powerful tool to identify new chemicals that interfere with complex biological processes. Here, we describe the identification of a new inhibitor of microtubule dynamics (micropolyin) using a high-content screen. Integrated high-resolution imaging allowed for fast selection of hits and progression to target identification. Treatment of cells with micropolyin efficiently causes a pro-metaphase arrest, with abnormal spindle morphology and with the spindle assembly checkpoint activated. The arrest appears to result from interference of micropolyin with microtubule dynamics. We show in vitro that tubulin is indeed the target of micropolyin and that micropolyin inhibits microtubule polymerization. Our results demonstrate the power of high-content image- and cell-based screening approaches to identify potential new drug candidates. As our approach is unbiased, it should allow for discovery of new targets that may otherwise be overlooked. [source] | ||||||||||||||||