The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
Toshio Matsushima - One of the best experts on this subject based on the ideXlab platform.
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decrease in leptomeningeal Ivy sign on fluid attenuated inversion recovery images after cerebral revascularization in patients with moyamoya disease
American Journal of Neuroradiology, 2010Co-Authors: Masatou Kawashima, Tomoyuki Noguchi, Yukinori Takase, Yukiko Nakahara, Toshio MatsushimaAbstract:BACKGROUND AND PURPOSE: The “Ivy” sign that is identified on FLAIR images in patients with Moyamoya disease is considered to be leptomeningeal collaterals. The aim of our study was to evaluate the correlation between postoperative decrease in Ivy sign and cerebral hemodynamic status in the bypass-established hemisphere. MATERIALS AND METHODS: Twenty-two patients with Moyamoya disease were enrolled. Postoperative changes in the Ivy sign on FLAIR images were examined in each patient after bypass surgery. The correlation between postoperative changes in the Ivy sign and hemodynamic status was examined in 10 patients by using SPECT. RESULTS: Of the 22 preoperative Ivy-positive patients, 21 showed decreased Ivy signs on the operative side. Average intervals between the operation day and the date when the decreased or vanished Ivy sign was first recognized were 157.6 days in patients who underwent direct bypass and 212.2 days in patients who underwent indirect bypass. A postoperative decrease in Ivy signs was found to be significantly correlated with an improved hemodynamic status of the surgically treated hemisphere, resulting in a postoperative increase in regional vascular reserve and a decreased proportion of the misery perfusion area ( P CONCLUSIONS: Postoperative changes in the Ivy sign can be used as a marker for identifying improved hemodynamics and also for testing the effectiveness of cerebral revascularization.
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unilateral hemispheric proliferation of Ivy sign on fluid attenuated inversion recovery images in moyamoya disease correlates highly with ipsilateral hemispheric decrease of cerebrovascular reserve
American Journal of Neuroradiology, 2009Co-Authors: Masatou Kawashima, Tomoyuki Noguchi, Yukinori Takase, T Ootsuka, N Kido, Toshio MatsushimaAbstract:BACKGROUND AND PURPOSE: An Ivy sign is considered to represent diffuse leptomeningeal collaterals found on fluid-attenuated inversion recovery (FLAIR) images of patients with Moyamoya disease. We evaluated the correlation between unilateral Ivy proliferation in a hemisphere and cerebrovascular hemodynamic status to learn the clinical significance of the Ivy sign. MATERIALS AND METHODS: A total of 35 patients with Moyamoya disease were included. Correlation between Ivy dominance on FLAIR images and hemodynamic status with use of iodine 123 N-isopropylp-iodoamphetamine ( 123 I-IMP) single-photon emission CT (SPECT) was evaluated. RESULTS: Distributional differences of Ivy signs between both hemispheres were observed in 22 (64.7%) of 34 patients with a positive Ivy sign, all of whom showed decreased vascular reserve/ reactivity in the Ivy-dominant hemisphere (IDH). The proportion of the stage II (misery perfusion) area to IDH was higher than that in the Ivy less-dominant hemisphere (ILDH) in the quantitative analysis. The mean vascular reserve was lower in IDH than ILDH. There were 15 of 22 patients who had bypass surgery on IDH because of transient ischemic attack from ischemia of IDH. Patients with symmetric Ivy distributions showed a variety of hemodynamic status. MR angiography (MRA) stage of IDH (2.95 0.39) was higher compared with ILDH (2.60 0.50; P .05). Regional arteriocapillary circulation time ratio in IDH was longer compared with ILDH (P .05). Ivy proliferation decreased in 10 (55.6%) of 18 patients who underwent bypass surgery during the follow-up period. CONCLUSIONS: Unilateral hemispheric Ivy proliferation correlated highly with the existence of an ipsilateral decreased vascular reserve associated with the development of leptomeningeal collaterals in patients with Moyamoya disease.
Mingjun Zhang - One of the best experts on this subject based on the ideXlab platform.
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nanospherical arabinogalactan proteins are a key component of the high strength adhesive secreted by english Ivy
Proceedings of the National Academy of Sciences of the United States of America, 2016Co-Authors: Yujian Huang, Mingjun Zhang, Yongzhong Wang, Jennifer M PetrosinoAbstract:Over 130 y have passed since Charles Darwin first discovered that the adventitious roots of English Ivy (Hedera helix) exude a yellowish mucilage that promotes the capacity of this plant to climb vertical surfaces. Unfortunately, little progress has been made in elucidating the adhesion mechanisms underlying this high-strength adhesive. In the previous studies, spherical nanoparticles were observed in the viscous exudate. Here we show that these nanoparticles are predominantly composed of arabinogalactan proteins (AGPs), a superfamily of hydroxyproline-rich glycoproteins present in the extracellular spaces of plant cells. The spheroidal shape of the AGP-rich Ivy nanoparticles results in a low viscosity of the Ivy adhesive, and thus a favorable wetting behavior on the surface of substrates. Meanwhile, calcium-driven electrostatic interactions among carboxyl groups of the AGPs and the pectic acids give rise to the cross-linking of the exuded adhesive substances, favor subsequent curing (hardening) via formation of an adhesive film, and eventually promote the generation of mechanical interlocking between the adventitious roots of English Ivy and the surface of substrates. Inspired by these molecular events, a reconstructed Ivy-mimetic adhesive composite was developed by integrating purified AGP-rich Ivy nanoparticles with pectic polysaccharides and calcium ions. Information gained from the subsequent tensile tests, in turn, substantiated the proposed adhesion mechanisms underlying the Ivy-derived adhesive. Given that AGPs and pectic polysaccharides are also observed in bioadhesives exuded by other climbing plants, the adhesion mechanisms revealed by English Ivy may forward the progress toward understanding the general principles underlying diverse botanic adhesives.
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Mechanics of the Adhesive Properties of Ivy Nanoparticles
2013Co-Authors: Mingjun ZhangAbstract:Abstract : The research objective of this proposal is to study the fundamental mechanics and mechanical properties of the nanoparticles-based adhesive secretion produced by Ivy rootlets for surface affixing and climbing. Both experimental and theoretical studies will be conducted. More generally, we aim to use insight from nature to elucidate theoretical principles governing the extraordinary adhesive properties of Ivy. The specific aims are: Specific Aim 1: Characterize the intra- and inter- molecular bonding forces and determine how they can be used to explain interactions that exist both between components of the Ivy adhesive secretion and between the secretion and the affixing surface. Specific Aim 2: Characterize the macroscopic mechanical properties of natural Ivy secretions. Specific Aim 3: Determine structure-property relationships via systematic alteration of the composition of the natural Ivy secretions. Specific Aim 4: Build finite element models (FEM) to quantitatively characterize and interpret the adhesive properties of Ivy nanoparticles. If successful, this research will elucidate the fundamental role of nanoparticles in determining the mechanical properties of Ivy surface affixing secretions, and will inspire bio-mimetic approaches for design of new materials with superior surface adhesion for military applications.
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Characterization of physicochemical properties of Ivy nanoparticles for cosmetic application
Journal of Nanobiotechnology, 2013Co-Authors: Yujian Huang, Scott C. Lenaghan, Jason N. Burris, C. Neal Stewart, Mingjun ZhangAbstract:Naturally occurring nanoparticles isolated from English Ivy (Hedera helix) have previously been proposed as an alternative to metallic nanoparticles as sunscreen fillers due to their effective UV extinction property, low toxicity and potential biodegradability. This study focused on analyzing the physicochemical properties of the Ivy nanoparticles, specifically, those parameters which are crucial for use as sunscreen fillers, such as pH, temperature, and UV irradiation. The visual transparency and cytotoxicity of Ivy nanoparticles were also investigated comparing them with other metal oxide nanoparticles. Results from this study demonstrated that, after treatment at 100°C, there was a clear increase in the UV extinction spectra of the Ivy nanoparticles caused by the partial decomposition. In addition, the UVA extinction spectra of the Ivy nanoparticles gradually reduced slightly with the decrease of pH values in solvents. Prolonged UV irradiation indicated that the influence of UV light on the stability of the Ivy nanoparticle was limited and time-independent. Compared to TiO2 and ZnO nanoparticles, Ivy nanoparticles showed better visual transparency. Methylthiazol tetrazolium assay demonstrated that Ivy nanoparticles exhibited lower cytotoxicity than the other two types of nanoparticles. Results also suggested that protein played an important role in modulating the three-dimensional structure of the Ivy nanoparticles. Based on the results from this study it can be concluded that the Ivy nanoparticles are able to maintain their UV protective capability at wide range of temperature and pH values, further demonstrating their potential as an alternative to replace currently available metal oxide nanoparticles in sunscreen applications.
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adhesion mechanics of Ivy nanoparticles
Journal of Colloid and Interface Science, 2010Co-Authors: Yu Wu, Xiaopeng Zhao, Mingjun ZhangAbstract:Abstract Adhesion mechanism of Ivy has been of major research interest for its potential applications in high-strength materials. Recent experimental studies demonstrated that nanoparticles secreted from Ivy tendrils play an important role in adhesion. In this work, we investigate how various factors such as van der Waals interaction, capillarity, and molecular cross-linking influence the adhesion mechanics of Ivy nanoparticles. This paper provides guidelines in choosing different adhesive contact models. Understanding the mechanics of Ivy adhesion could potentially inspire the design and fabrication of novel nano-bio-materials.
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Atomic Force Microscopy Study of Ivy Climbing Mechanism
2008 8th IEEE Conference on Nanotechnology, 2008Co-Authors: Mingjun ZhangAbstract:This paper presents our recent discovery on Ivy climbing mechanism and proposes a potential biology inspired climbing mechanism for nano-applications. Using atomic force microscope (AFM), we observed Ivy secrets nanoparticles through adhering disks of the aerial rootlets to affix to a surface. The study suggests that nanoparticles play a direct role for Ivy surface climbing. Weak adhesion and hydrogen bonding seem to be the forces for the climbing mechanism. This Ivy secretion mechanism may inspire new methods for synthesizing nanoparticles biologically or new approaches to adhesion mechanisms for nano applications.
Masatou Kawashima - One of the best experts on this subject based on the ideXlab platform.
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decrease in leptomeningeal Ivy sign on fluid attenuated inversion recovery images after cerebral revascularization in patients with moyamoya disease
American Journal of Neuroradiology, 2010Co-Authors: Masatou Kawashima, Tomoyuki Noguchi, Yukinori Takase, Yukiko Nakahara, Toshio MatsushimaAbstract:BACKGROUND AND PURPOSE: The “Ivy” sign that is identified on FLAIR images in patients with Moyamoya disease is considered to be leptomeningeal collaterals. The aim of our study was to evaluate the correlation between postoperative decrease in Ivy sign and cerebral hemodynamic status in the bypass-established hemisphere. MATERIALS AND METHODS: Twenty-two patients with Moyamoya disease were enrolled. Postoperative changes in the Ivy sign on FLAIR images were examined in each patient after bypass surgery. The correlation between postoperative changes in the Ivy sign and hemodynamic status was examined in 10 patients by using SPECT. RESULTS: Of the 22 preoperative Ivy-positive patients, 21 showed decreased Ivy signs on the operative side. Average intervals between the operation day and the date when the decreased or vanished Ivy sign was first recognized were 157.6 days in patients who underwent direct bypass and 212.2 days in patients who underwent indirect bypass. A postoperative decrease in Ivy signs was found to be significantly correlated with an improved hemodynamic status of the surgically treated hemisphere, resulting in a postoperative increase in regional vascular reserve and a decreased proportion of the misery perfusion area ( P CONCLUSIONS: Postoperative changes in the Ivy sign can be used as a marker for identifying improved hemodynamics and also for testing the effectiveness of cerebral revascularization.
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unilateral hemispheric proliferation of Ivy sign on fluid attenuated inversion recovery images in moyamoya disease correlates highly with ipsilateral hemispheric decrease of cerebrovascular reserve
American Journal of Neuroradiology, 2009Co-Authors: Masatou Kawashima, Tomoyuki Noguchi, Yukinori Takase, T Ootsuka, N Kido, Toshio MatsushimaAbstract:BACKGROUND AND PURPOSE: An Ivy sign is considered to represent diffuse leptomeningeal collaterals found on fluid-attenuated inversion recovery (FLAIR) images of patients with Moyamoya disease. We evaluated the correlation between unilateral Ivy proliferation in a hemisphere and cerebrovascular hemodynamic status to learn the clinical significance of the Ivy sign. MATERIALS AND METHODS: A total of 35 patients with Moyamoya disease were included. Correlation between Ivy dominance on FLAIR images and hemodynamic status with use of iodine 123 N-isopropylp-iodoamphetamine ( 123 I-IMP) single-photon emission CT (SPECT) was evaluated. RESULTS: Distributional differences of Ivy signs between both hemispheres were observed in 22 (64.7%) of 34 patients with a positive Ivy sign, all of whom showed decreased vascular reserve/ reactivity in the Ivy-dominant hemisphere (IDH). The proportion of the stage II (misery perfusion) area to IDH was higher than that in the Ivy less-dominant hemisphere (ILDH) in the quantitative analysis. The mean vascular reserve was lower in IDH than ILDH. There were 15 of 22 patients who had bypass surgery on IDH because of transient ischemic attack from ischemia of IDH. Patients with symmetric Ivy distributions showed a variety of hemodynamic status. MR angiography (MRA) stage of IDH (2.95 0.39) was higher compared with ILDH (2.60 0.50; P .05). Regional arteriocapillary circulation time ratio in IDH was longer compared with ILDH (P .05). Ivy proliferation decreased in 10 (55.6%) of 18 patients who underwent bypass surgery during the follow-up period. CONCLUSIONS: Unilateral hemispheric Ivy proliferation correlated highly with the existence of an ipsilateral decreased vascular reserve associated with the development of leptomeningeal collaterals in patients with Moyamoya disease.
Shoki Takahashi - One of the best experts on this subject based on the ideXlab platform.
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the leptomeningeal Ivy sign on fluid attenuated inversion recovery mr imaging in moyamoya disease a sign of decreased cerebral vascular reserve
American Journal of Neuroradiology, 2009Co-Authors: N Mori, Shunji Mugikura, Shuichi Higano, Tomohiro Kaneta, Miki Fujimura, Atsushi Umetsu, Takaki Murata, Shoki TakahashiAbstract:BACKGROUND AND PURPOSE: Moyamoya disease is an idiopathic occlusive cerebrovascular disorder with abnormal microvascular proliferation. We investigated the clinical utility of leptomeningeal high signal intensity (Ivy sign) sometimes seen on fluid-attenuated inversion recovery images in Moyamoya disease. MATERIALS AND METHODS: We examined the relationship between the degree of the Ivy sign and the severity of the ischemic symptoms in 96 hemispheres of 48 patients with Moyamoya disease. We classified each cerebral hemisphere into 4 regions from anterior to posterior. In 192 regions of 24 patients, we examined the relationship between the degree of the Ivy sign and findings of single-photon emission CT, including the resting cerebral blood flow (CBF) and cerebral vascular reserve (CVR). RESULTS: The degree of the Ivy sign showed a significant positive relationship with the severity of the ischemic symptoms ( P P P CONCLUSIONS: The leptomeningeal Ivy sign indicates decreased CVR in Moyamoya disease.
Christiaan Michiels - One of the best experts on this subject based on the ideXlab platform.
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role of the lysozyme inhibitor Ivy in growth or survival of escherichia coli and pseudomonas aeruginosa bacteria in hen egg white and in human saliva and breast milk
Applied and Environmental Microbiology, 2008Co-Authors: Daphne Deckers, Dietrich Vanlint, Lien Callewaert, Abram Aertsen, Christiaan MichielsAbstract:Ivy is a lysozyme inhibitor that protects Escherichia coli against lysozyme-mediated cell wall hydrolysis when the outer membrane is permeabilized by mutation or by chemical or physical stress. In the current work, we have investigated whether Ivy is necessary for the survival or growth of E. coli MG1655 and Pseudomonas aeruginosa PAO1 in hen egg white and in human saliva and breast milk, which are naturally rich in lysozyme and in membrane-permeabilizing components. Wild-type E. coli was able to grow in saliva and breast milk but showed partial inactivation in egg white. The knockout of Ivy did not affect growth in breast milk but slightly increased sensitivity to egg white and caused hypersensitivity to saliva, resulting in the complete inactivation of 104 CFU ml−1 of bacteria within less than 5 hours. The depletion of lysozyme from saliva completely restored the ability of the Ivy mutant to grow like the parental strain. P. aeruginosa, in contrast, showed growth in all three substrates, which was not affected by the knockout of Ivy production. These results indicate that lysozyme inhibitors like Ivy promote bacterial survival or growth in particular lysozyme-rich secretions and suggest that they may promote the bacterial colonization of specific niches in the animal host.
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purification of Ivy a lysozyme inhibitor from escherichia coli and characterisation of its specificity for various lysozymes
Enzyme and Microbial Technology, 2005Co-Authors: Lien Callewaert, Daphne Deckers, Abram Aertsen, Barbara Masschalck, Dorothy Nakimbugwe, Miroslava Atanassova, Christiaan MichielsAbstract:A highly efficient method was developed for the isolation and purification of the periplasmic Escherichia coli lysozyme inhibitor protein Ivy. After isolation by osmotic shock from an E. coli overexpression strain, Ivy was purified to >95% purity using a single affinity chromatography step with hen egg white lysozyme as a ligand. Further, the specificity of Ivy against various types of lysozymes (hen egg white lysozyme, c-type; mutanolysine, ch-type; cauliflower lysozyme, not further classified; goose egg white lysozyme, g-type; lambda lysozyme, λ-type and T4 lysozyme, v-type) was investigated. Most strongly inhibited was hen egg white lysozyme, followed by goose egg white lysozyme and finally T4 lysozyme, while no inhibition was observed for the other lysozymes. These results clearly indicate that Ivy is a relatively specific inhibitor of vertebrate lysozymes belonging to the c- and g-type and that its inhibition profile corresponds to the structural and evolutionary relatedness of the lysozymes. The availability of pure Ivy and the elucidation of its inhibition profile will contribute to the further identification of its biological function in bacteria.
