keyword
MENU ▼
Read by QxMD icon Read
search

Electron tomography

keyword
https://www.readbyqxmd.com/read/28339603/optimization-of-stem-imaging-conditions-for-cryo-tomography
#1
Kazuhiro Aoyama, Kotaro Nagano, Kaoru Mitsuoka
For three-dimensional analysis of cryo-specimens using tomography at low and medium magnifications, the use of STEM images has some important advantages over TEM. A clear understanding of the electron dose in STEM is essential for optimized cryo-microscopy so a dose estimation technique for STEM imaging has been developed. The STEM convergence angle was shown to have a large impact on the image quality, in particular on the signal-to-noise ratio in the acquired images. Importantly, there is a clear trade-off between good STEM spatial resolution in the images with a large convergence angle and the signal-to-noise ratio, which is improved by reducing the convergence angle as much as possible...
February 9, 2017: Microscopy
https://www.readbyqxmd.com/read/28338814/korean-pediatric-and-adult-head-computational-phantoms-and-application-to-photon-specific-absorbed-fractions-calculations
#2
Daphnée Villoing, Dayton McMillan, Kwang Pyo Kim, Il Park, Ae-Kyoung Lee, Hyung-do Choi, Choonsik Lee
In recent decades, applications of single photon emission computed tomography and positron emission tomography in clinical neuroimaging have markedly increased. In this study, we developed a series of Korean computational head phantoms with detailed cranial substructures for 6-, 9-, 12- and 15-year-old children and adult by non-uniformly adjusting a template head phantom to match the Korean standard head dimensions. The Korean head phantoms were coupled with a Monte Carlo transport code to calculate age-dependent specific absorbed fraction (SAF) for the combination of 10 source and target regions and mono-energetic photons ranging from 0...
February 23, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/28336782/functional-imaging-signature-of-patients-presenting-with-polycythemia-paraganglioma-syndromes
#3
Ingo Janssen, Clara Chi Chen, Zhenping Zhuang, Corina M Millo, Katherine Wolf, Alexander Ling, Frank I Lin, Karen T Adams, Peter Herscovitch, Richard A Feelders, Antonio T Fojo, David Taieb, Electron Kebebew, Karel Pacak
Rationale: Pheochromocytoma/paraganglioma (PPGL) syndromes associated with polycythemia have previously been described in association with mutations in the von Hippel-Lindau (VHL) gene. Recently, mutations in the prolyl hydroxylase gene (PHD) 1 and 2 and in the hypoxia-inducible factor 2 alpha (HIF2A) were also found to be associated with multiple and recurrent PPGL. Such patients also presented with PPGL and polycythemia, and later on, some presented with duodenal somatostatinoma. In additional patients presenting with PPGL and polycythemia, no further mutations have been discovered...
March 23, 2017: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
https://www.readbyqxmd.com/read/28336315/cardiolipin-and-mitochondrial-cristae-organization
#4
REVIEW
Nikita Ikon, Robert O Ryan
A fundamental question in cell biology, under investigation for over six decades, is the structural organization of mitochondrial cristae. Long known to harbor electron transport chain proteins, crista membrane integrity is key to establishment of the proton gradient that drives oxidative phosphorylation. Visualization of cristae morphology by electron microscopy / tomography has provided evidence that cristae are tube-like extensions of the mitochondrial inner membrane (IM) that project into the matrix space...
March 20, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28332496/cell-free-reconstitution-reveals-centriole-cartwheel-assembly-mechanisms
#5
P Guichard, V Hamel, M Le Guennec, N Banterle, I Iacovache, V Nemčíková, I Flückiger, K N Goldie, H Stahlberg, D Lévy, B Zuber, P Gönczy
How cellular organelles assemble is a fundamental question in biology. The centriole organelle organizes around a nine-fold symmetrical cartwheel structure typically ∼100 nm high comprising a stack of rings that each accommodates nine homodimers of SAS-6 proteins. Whether nine-fold symmetrical ring-like assemblies of SAS-6 proteins harbour more peripheral cartwheel elements is unclear. Furthermore, the mechanisms governing ring stacking are not known. Here we develop a cell-free reconstitution system for core cartwheel assembly...
March 23, 2017: Nature Communications
https://www.readbyqxmd.com/read/28332331/computed-tomography-for-head-injuries-in-children-change-in-australian-usage-rates-over-time
#6
Ed Oakley, Rachel May, Tobias Hoeppner, Kam Sinn, Jeremy Furyk, Simon Craig, Pamela Rosengarten, Amit Kochar, David Krieser, Sarah Dalton, Stuart Dalziel, Jocelyn Neutze, Tim Cain, Kim Jachno, Franz E Babl
OBJECTIVE: Paediatric head injury is a common presentation to the ED. North American studies demonstrate increasing use of computed tomography (CT) brain scan (CTB) to investigate head injury. No such data exists for Australian EDs. The aim of this study was to describe CTB use in head injury over time in eight Australian EDs. METHODS: Retrospective ED electronic database and medical imaging database audit was undertaken for the years 2001-2010 by International Classification of Diseases (ICD) 9 or 10 code for head injury in children <16 years...
April 2017: Emergency Medicine Australasia: EMA
https://www.readbyqxmd.com/read/28330771/deciphering-the-molecular-architecture-of-membrane-contact-sites-by-cryo-electron-tomography
#7
REVIEW
Javier Collado, Rubén Fernández-Busnadiego
At membrane contact sites (MCS) two cellular membranes form tight appositions that play critical roles in fundamental phenomena such as lipid metabolism or Ca(2+) homeostasis. The interest for these structures has surged in recent years, bringing about the characterization of a plethora of MCS-resident molecules. How those molecules are structurally organized at MCS remains enigmatic, limiting our understanding of MCS function. Whereas such molecular detail is obscured by conventional electron microscopy sample preparation, cryo-electron tomography (cryo-ET) is uniquely positioned to address this challenge by allowing high resolution imaging of cellular landscapes in close-to-native conditions...
March 19, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28329122/prognostic-implications-of-left-ventricular-asymmetry-in-patients-with-asymptomatic-aortic-valve-stenosis
#8
Per Ejlstrup Sigvardsen, Linnea Hornbech Larsen, Helle Gervig Carstensen, Mathias Sørgaard, Louise Hindsø, Christian Hassager, Lars Køber, Rasmus Møgelvang, Klaus Fuglsang Kofoed
Aims: Left ventricular (LV) regional hypertrophy in the form of LV asymmetry is a common finding in patients with aortic valve stenosis. The aim of this study was to test the hypothesis that LV asymmetry predicts future symptomatic status and indication for aortic valve replacement (AVR) in patients with asymptomatic aortic valve stenosis. Methods and results: In total, 114 patients with asymptomatic aortic valve stenosis (peak velocity > 2.5 m/s assessed by echocardiographic screening and LV ejection fraction > 50%) were enrolled in the study...
February 18, 2017: European Heart Journal Cardiovascular Imaging
https://www.readbyqxmd.com/read/28329057/coronary-artery-calcification-and-risk-of-cardiovascular-disease-and-death-among-patients-with-chronic-kidney-disease
#9
Jing Chen, Matthew J Budoff, Muredach P Reilly, Wei Yang, Sylvia E Rosas, Mahboob Rahman, Xiaoming Zhang, Jason A Roy, Eva Lustigova, Lisa Nessel, Virginia Ford, Dominic Raj, Anna C Porter, Elsayed Z Soliman, Jackson T Wright, Myles Wolf, Jiang He
Importance: Coronary artery calcification (CAC) is highly prevalent in dialysis-naive patients with chronic kidney disease (CKD). However, there are sparse data on the association of CAC with subsequent risk of cardiovascular disease and all-cause mortality in this population. Objective: To study the prospective association of CAC with risk of cardiovascular disease and all-cause mortality among dialysis-naive patients with CKD. Design, Setting, and Participants: The prospective Chronic Renal Insufficiency Cohort study recruited adults with an estimated glomerular filtration rate of 20 to 70 mL/min/1...
March 22, 2017: JAMA Cardiology
https://www.readbyqxmd.com/read/28326714/-effect-of-pinus-massoniana-needle-extract-on-root-dentin-demineralization-in-vitro
#10
Tang Chengfang, Ruan Jianping, Zhu Yong, Li Zixia, Zuo Yanping, Xu Hongyan
OBJECTIVE: This study aims to evaluate the effects of Pinus massoniana needle extract (PMNE) on inhibiting demineralization of root dentin. METHODS: Root dentin blocks were randomly divided into distilled deionized water (DDW) group, fluoride sodium (NaF) group, and 4%, 8% and 12% PMNE groups according to the experimental solution used in the process of pH cycling in each group. All specimens in each group experienced pH cycling for 8 d. The dentin mineral density (DMD) of the normal dentin and demineralized dentin and their D-value (ΔDMD) were determined using micro computed tomography...
October 1, 2016: Hua Xi Kou Qiang Yi Xue za Zhi, Huaxi Kouqiang Yixue Zazhi, West China Journal of Stomatology
https://www.readbyqxmd.com/read/28326234/self-assembly-of-silicon-nanowires-studied-by-advanced-transmission-electron-microscopy
#11
Marta Agati, Guillaume Amiard, Vincent Le Borgne, Paola Castrucci, Richard Dolbec, Maurizio De Crescenzi, My Alì El Khakani, Simona Boninelli
Scanning transmission electron microscopy (STEM) was successfully applied to the analysis of silicon nanowires (SiNWs) that were self-assembled during an inductively coupled plasma (ICP) process. The ICP-synthesized SiNWs were found to present a Si-SiO2 core-shell structure and length varying from ≈100 nm to 2-3 μm. The shorter SiNWs (maximum length ≈300 nm) were generally found to possess a nanoparticle at their tip. STEM energy dispersive X-ray (EDX) spectroscopy combined with electron tomography performed on these nanostructures revealed that they contain iron, clearly demonstrating that the short ICP-synthesized SiNWs grew via an iron-catalyzed vapor-liquid-solid (VLS) mechanism within the plasma reactor...
2017: Beilstein Journal of Nanotechnology
https://www.readbyqxmd.com/read/28323617/cryoem-structures-of-membrane-pore-and-prepore-complex-reveal-cytolytic-mechanism-of-pneumolysin
#12
Katharina van Pee, Alexander Neuhaus, Edoardo D'Imprima, Deryck J Mills, Werner Kühlbrandt, Özkan Yildiz
Many pathogenic bacteria produce pore-forming toxins to attack and kill human cells. We have determined the 4.5 Å structure of the ~2.2 MDa pore complex of pneumolysin, the main virulence factor of Streptococcus pneumoniae, by cryoEM. The pneumolysin pore is a 400 Å ring of 42 membrane-inserted monomers. Domain D3 of the soluble toxin refolds into two ~85 Å β-hairpins that traverse the lipid bilayer and assemble into a 168-strand β-barrel. The pore complex is stabilized by salt bridges between β-hairpins of adjacent subunits and an internal α-barrel...
March 21, 2017: ELife
https://www.readbyqxmd.com/read/28323098/an-innovative-method-for-the-preparation-of-high-api-loaded-hollow-spherical-granules-for-use-in-controlled-release-formulation
#13
Takumi Asada, Mitsuaki Kobiki, Yasushi Ochiai, Yasunori Iwao, Shigeru Itai
The aim of this study was to prepare controlled-release (CR) granules with suitable particle strength, flowability, particle size distribution (PSD) and density characteristics for blending with other excipients. We also wanted these CR granules to contain large quantities of active pharmaceutical ingredient (API). A high shear mixer was used to mix an API with various polymers at various feed ratios, and the resulting granulated materials were sprayed with solvent. The wet granules were dried using a fluidized bed dryer to give CR granules...
March 18, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28320562/microstructural-characterization-of-dental-zinc-phosphate-cements-using-combined-small-angle-neutron-scattering-and-microfocus-x-ray-computed-tomography
#14
Alberto Viani, Konstantinos Sotiriadis, Ivana Kumpová, Lucia Mancini, Marie-Sousai Appavou
OBJECTIVE: To characterize the microstructure of two zinc phosphate cement formulations in order to investigate the role of liquid/solid ratio and composition of powder component, on the developed porosity and, consequently, on compressive strength. METHODS: X-ray powder diffraction with the Rietveld method was used to study the phase composition of zinc oxide powder and cements. Powder component and cement microstructure were investigated with scanning electron microscopy...
February 17, 2017: Dental Materials: Official Publication of the Academy of Dental Materials
https://www.readbyqxmd.com/read/28318141/zika-virus-induced-cellular-remodeling
#15
Evan D Rossignol, Kristen N Peters, John H Connor, Esther Bullitt
Zika virus (ZIKV) has been associated with morbidities such as Guillain-Barré, infant microcephaly, and ocular disease. The spread of this positive-sense, single-stranded RNA virus and its growing public health threat underscore gaps in our understanding of basic ZIKV virology. To advance knowledge of the virus replication cycle within mammalian cells, we use serial section three-dimensional electron tomography to demonstrate the widespread remodeling of intracellular membranes upon infection with ZIKV. We report extensive structural rearrangements of the endoplasmic reticulum and reveal stages of the ZIKV viral replication cycle...
March 20, 2017: Cellular Microbiology
https://www.readbyqxmd.com/read/28306555/assessment-of-dosimetric-impact-of-system-specific-geometric-distortion-in-an-mri-only-based-radiotherapy-workflow-for-prostate
#16
C Gustafsson, F Nordström, E Persson, J Brynolfsson, L E Olsson
Dosimetric errors in a magnetic resonance imaging (MRI) only radiotherapy workflow may be caused by system specific geometric distortion from MRI. The aim of this study was to evaluate the impact on planned dose distribution and delineated structures for prostate patients, originating from this distortion. A method was developed, in which computer tomography (CT) images were distorted using the MRI distortion field. The displacement map for an optimized MRI treatment planning sequence was measured using a dedicated phantom in a 3 T MRI system...
March 17, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28302947/in-vivo-bioactivity-of-porous-polyetheretherketone-with-a-foamed-surface
#17
Ayato Hieda, Naoya Uemura, Yoshiya Hashimoto, Isumi Toda, Shunsuke Baba
The in vivo bioactivity of porous polyetheretherketone (PEEK) with a foamed surface was evaluated using rabbit femoral bone. Cylindrical porous PEEK scaffolds, with pore diameter of 550 μm and porosity of 70%, were first prepared and immersed in 98% sulfuric acid, and then washed and immersed in 3 M potassium carbonate solution used as a foaming reagent. Numerous open pores of various sizes, as well as new functional groups, were visualized on the treated PEEK surface by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively...
March 8, 2017: Dental Materials Journal
https://www.readbyqxmd.com/read/28298114/a-novel-quantum-dynamical-approach-in-electron-microscopy-combining-wave-packet-propagation-with-bohmian-trajectories
#18
S Rudinsky, A S Sanz, R Gauvin
The numerical analysis of the diffraction features rendered by transmission electron microscopy typically relies either on classical approximations (Monte Carlo simulations) or quantum paraxial tomography (the multislice method and any of its variants). Although numerically advantageous (relatively simple implementations and low computational costs), they involve important approximations and thus their range of applicability is limited. To overcome such limitations, an alternative, more general approach is proposed, based on an optimal combination of wave-packet propagation with the on-the-fly computation of associated Bohmian trajectories...
March 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28292906/parasitophorous-vacuole-poration-precedes-its-rupture-and-rapid-host-erythrocyte-cytoskeleton-collapse-in-plasmodium-falciparum-egress
#19
Victoria L Hale, Jean M Watermeyer, Fiona Hackett, Gema Vizcay-Barrena, Christiaan van Ooij, James A Thomas, Matthew C Spink, Maria Harkiolaki, Elizabeth Duke, Roland A Fleck, Michael J Blackman, Helen R Saibil
In the asexual blood stages of malarial infection, merozoites invade erythrocytes and replicate within a parasitophorous vacuole to form daughter cells that eventually exit (egress) by sequential rupture of the vacuole and erythrocyte membranes. The current model is that PKG, a malarial cGMP-dependent protein kinase, triggers egress, activating malarial proteases and other effectors. Using selective inhibitors of either PKG or cysteine proteases to separately inhibit the sequential steps in membrane perforation, combined with video microscopy, electron tomography, electron energy loss spectroscopy, and soft X-ray tomography of mature intracellular Plasmodium falciparum parasites, we resolve intermediate steps in egress...
March 14, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28292687/x-ray-absorption-in-pillar-shaped-transmission-electron-microscopy-specimens
#20
H Bender, F Seidel, P Favia, O Richard, W Vandervorst
The dependence of the X-ray absorption on the position in a pillar shaped transmission electron microscopy specimen is modeled for X-ray analysis with single and multiple detector configurations and for different pillar orientations relative to the detectors. Universal curves, applicable to any pillar diameter, are derived for the relative intensities between weak and medium or strongly absorbed X-ray emission. For the configuration as used in 360° X-ray tomography, the absorption correction for weak and medium absorbed X-rays is shown to be nearly constant along the pillar diameter...
March 7, 2017: Ultramicroscopy
keyword
keyword
9222
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"