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Dynamic contrast

Tobias Wech, Herbert Köstler
PURPOSE: To introduce and evaluate an image registration technique for robust quantification of CEST acquisitions corrupted by motion. METHODS: The proposed iterative algorithm exploits a low-rank approximation of the z-spectrum (LRAZ), to gradually separate the contrast variation due to saturation at different off-resonance frequencies and accompanying motion. This registration method was first tested in a creatine CEST analysis of a phantom with simulated rigid motion...
April 15, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Barry J Maron, Ethan J Rowin, James E Udelson, Martin S Maron
Heart failure (HF), characterized by excessive exertional dyspnea, is a common complication within the broad clinical spectrum of hypertrophic cardiomyopathy (HCM). HF has become an increasingly prominent management issue with the reduction in sudden deaths due to use of implantable defibrillators in this disease. Exertional dyspnea ranges in severity from mild to severe (New York Heart Association functional classes II to IV) and not uncommonly becomes refractory to medical management, leading to progressive disability, but largely in the absence of pulmonary congestion and volume overload requiring hospitalization...
April 5, 2018: JACC. Heart Failure
Tomer D Ullman, Andreas Stuhlmüller, Noah D Goodman, Joshua B Tenenbaum
Humans acquire their most basic physical concepts early in development, and continue to enrich and expand their intuitive physics throughout life as they are exposed to more and varied dynamical environments. We introduce a hierarchical Bayesian framework to explain how people can learn physical parameters at multiple levels. In contrast to previous Bayesian models of theory acquisition (Tenenbaum, Kemp, Griffiths, & Goodman, 2011), we work with more expressive probabilistic program representations suitable for learning the forces and properties that govern how objects interact in dynamic scenes unfolding over time...
April 10, 2018: Cognitive Psychology
Weifu Chen, Mingquan Lin, Eli Gibson, Matthew Bastian-Jordan, Derek W Cool, Zahra Kassam, Huageng Liang, Guocan Feng, Aaron D Ward, Bernard Chiu
Multiparametric magnetic resonance imaging (mpMRI) has been established as the state-of-the-art examination for the detection and localization of prostate cancer lesions. Prostate Imaging-Reporting and Data System (PI-RADS) has been established as a scheme to standardize the reporting of mpMRI findings. Although lesion delineation and PI-RADS ratings could be performed manually, human delineation and ratings are subjective and time-consuming. In this article, we developed and validated a self-tuned graph-based model for PI-RADS rating prediction...
April 3, 2018: Computers in Biology and Medicine
Liling Zhao, Zanxia Cao, Yunqiang Bian, Guodong Hu, Jihua Wang, Yaoqi Zhou
Cathelicidins are a large family of cationic antimicrobial peptides (AMPs) found in mammals with broad spectrum antimicrobial activity. LL-37 is the sole amphipathic α-helical AMP from human Cathelicidins family. In addition to its bactericidal capability, LL-37 has antiviral, anti-tumor, and immunoregulatory activity. Despite many experimental studies, its molecular mechanism of action is not yet fully understood. Here, we performed three independent molecular dynamics simulations (600 ns or more) of a LL-37 peptide in the presence of 256 lipid bilayers with 1-palmitoyl-2-oleoyl- sn -glycero-3-phosphoglycerol (POPG) mimicking bacterial and 1-palmitoyl-2-oleoyl- sn -glycero-3-phosphocholine (POPC) mimicking mammalian membranes...
April 13, 2018: International Journal of Molecular Sciences
Toshiaki Taoka, Gregor Jost, Thomas Frenzel, Shinji Naganawa, Hubertus Pietsch
OBJECTIVES: The glymphatic system is a recently hypothesized waste clearance system of the brain in which perivascular space constitutes a pathway similar to the lymphatic system in other body regions. Sleep and anesthesia are reported to influence the activity of the glymphatic system. Because rats are nocturnal animals, the glymphatic system is expected to be more active during the day. We attempted to elucidate the influence of the glymphatic system for intravenously injected gadodiamide in the rat brain by 2 experiments...
April 12, 2018: Investigative Radiology
Erik Frotscher, Georg Krainer, Michael Schlierf, Sandro Keller
The structural dynamics of proteins on the nanosecond timescale can be probed with dipolar relaxation in response to photoexcitation of intrinsic tryptophan (Trp) residues. For membrane proteins, however, the complexity due to overlapping contributions from the protein itself, the membrane mimic, and the aqueous solvent impairs detailed analysis and interpretation. To disentangle these contributions, we measured time-resolved emission spectra of Trp in the protein Mistic in detergent micelles of various polarities...
April 13, 2018: Journal of Physical Chemistry Letters
Rong Chen, Shin-Ho Chung
Molecular dynamics simulations are employed to determine the inhibitory mechanisms of three drugs, 5-(4- phenoxybutoxy)psoralen (PAP-1), vernakalant and flecainide, on the voltage-gated K+ channel Kv1.5, a target for the treatment of cardiac arrhythmia. At neutral pH, PAP-1 is neutral, whereas the other two molecules carry one positive charge. We show that PAP-1 forms stable dimers in water, primarily through the hydrophobic interactions between aromatic rings. All three molecules bind to the cavity between the Ile508 and Val512 residues from the four subunits of the channel...
April 13, 2018: Biochemistry
David A Hopper, Richard R Grote, Samuel M Parks, Lee C Bassett
Nanodiamonds containing nitrogen-vacancy (NV) centers offer a versatile platform for sensing applications spanning from nanomagnetism to in-vivo monitoring of cellular processes. In many cases, however, weak optical signals and poor contrast demand long acquisition times that prevent the measurement of environmental dynamics. Here, we demonstrate the ability to perform fast, high-contrast optical measurements of charge distributions in ensembles of NV centers in nanodiamonds and use the technique to improve the spin readout signal-to-noise ratio through spin-to-charge conversion...
April 13, 2018: ACS Nano
Julia M Rohrer, Stefan C Schmukle
Bottom-up models of life satisfaction are based on the assumption that individuals judge the overall quality of their lives by aggregating information across various life domains, such as health, family, and income. This aggregation supposedly involves a weighting procedure because individuals care about different parts of their lives to varying degrees. Thus, composite measures of well-being should be more accurate if domain satisfaction scores are weighted by the importance that respondents assign to the respective domains...
2018: Collabra. Psychology
Jos Eacute Manuel Encarnaci Oacute N Escobar, Erik Dietrich, Steve Arscott, Harold J W Zandvliet, Xuehua Zhang, Detlef Lohse
The control of the surface wettability is of great interest for technological applica- tions as well as for the fundamental understanding of surface phenomena. In this paper we describe the dissolution behavior of droplets wetting a micro-patterned surface con- sisting of smooth concentric circular grooves. In the experiments, a droplet of alcohol (1-Pentanol) is placed onto water immersed micro-patterns. When the drops dissolve the dynamics of the receding contact line occurs in two different modes. In addition to the stick-jump mode with jumps from one ring to the next inner one, our study reveals a second dissolution mode, which we refer to as zipping-dewetting...
April 13, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Joseph J Crisco, Nikolas J Osvalds, Michael J Rainbow
The purpose of this study was to compute the three-dimensional kinetics required to swing three youth baseball bats of varying moments of inertia (MOI). 306 swings by 22 male players (13-18 yrs.) were analyzed. Inverse dynamics with respect to the batter's hands were computed given the known kinematics and physical properties of the bats. We found that peak force increased with larger bat MOI and was strongly correlated with bat tip speed. In contrast, peak moments were weakly correlated with bat MOI and bat tip speed...
April 13, 2018: Journal of Applied Biomechanics
Clara Atterby, Evangelos Mourkas, Guillaume Méric, Ben Pascoe, Helen Wang, Jonas Waldenström, Samuel K Sheppard, Björn Olsen, Josef D Järhult, Patrik Ellström
Campylobacter jejuni is the primary cause of bacterial gastroenteritis worldwide, infecting humans mostly through consumption of contaminated poultry. C. jejuni is common in the gut of wild birds, and shows distinct strain-specific association to particular bird species. This contrasts with farm animals, in which several genotypes co-exist. It is unclear if the barriers restricting transmission between host species of such specialist strains are related to environmental factors such as contact between host species, bacterial survival in the environment, etc...
2018: Frontiers in Microbiology
K A Morales, J Arevalo-Perez, K K Peck, A I Holodny, E Lis, S Karimi
BACKGROUND AND PURPOSE: Vertebral hemangiomas are benign vascular lesions that are almost always incidentally found in the spine. Their classic typical hyperintense appearance on T1- and T2-weighted MR images is diagnostic. Unfortunately, not all hemangiomas have the typical appearance, and they can mimic metastases on routine MR imaging. These are generally referred to as atypical hemangiomas and can result in misdiagnosis and ultimately additional imaging, biopsy, and unnecessary costs...
April 12, 2018: AJNR. American Journal of Neuroradiology
Gregory A Ross, Ariën S Rustenburg, Patrick B Grinaway, Josh Fass, John Damon Chodera
Biomolecular simulations are typically performed in an aqueous environment where the number of ions remains fixed for the duration of the simulation, generally with either a minimally neutralizing ion environment or a number of salt pairs intended to match the macroscopic salt concentration. In contrast, real biomolecules experience local ion environments where the salt concentration is dynamic and may differ from bulk. The degree of salt concentration variability and average deviation from the macroscopic concentration remains, as yet, unknown...
April 13, 2018: Journal of Physical Chemistry. B
Fakhrossadat Emami, Alireza Vatanara, Abdolhosein Rouholamini Najafabadi, Yejin Kim, Eun Ji Park, Soroush Sardari, Dong Hee Na
The purpose of this study was to prepare spray freeze-dried particles of immunoglobulin G (IgG) using various combinations of trehalose and different amino acids (leucine, phenylalanine, arginine, cysteine, and glycine), and investigate the effect of the amino acids on the stability of IgG during the spray freeze-drying (SFD) process and storage. The morphology and structural integrity of the processed nanoparticles were evaluated by physical and spectroscopic techniques. SFD-processed IgG without any excipient resulted in the formation of aggregates corresponding to approximately 14% of IgG...
April 9, 2018: European Journal of Pharmaceutical Sciences
Yunash Maharjan, Joon No Lee, SeongAe Kwak, Hyewon Lim, Raghbendra Kumar Dutta, Zhi-Qiang Liu, Hong-Seob So, Raekil Park
Primary cilium is a microtubule structure that emanates from the surface of most human cells. Primary cilia assemble during the resting stage (G0 phase) and disassemble with cell cycle progression. Defects associated with the control of the assembly or disassembly of the primary cilium have been implicated in various human diseases, including ciliopathy and cancer. Although studies have suggested the interplay between activation of autophagy and ciliogenesis, any direct mechanism between autophagy abatement and disassembly of primary cilium remains elusive...
April 9, 2018: Biochemical and Biophysical Research Communications
Sang Yu Nam, Eun Sook Ko, Yaeji Lim, Boo-Kyung Han, Eun Young Ko, Ji Soo Choi, Jeong Eon Lee
OBJECTIVES: To evaluate whether preoperative breast dynamic contrast-enhanced (DCE) magnetic resonance (MR) imaging kinetic features, assessed using computer-aided diagnosis (CAD), can predict survival outcome and tumor aggressiveness in patients with invasive breast cancer. MATERIALS AND METHODS: Between March and December 2011, 301 women who underwent preoperative DCE MR imaging for invasive breast cancer, with CAD data, were identified. All MR images were retrospectively evaluated using a commercially available CAD system...
2018: PloS One
Robert Mahen
The centrosome is a non-membrane-bound cellular compartment consisting of 2 centrioles surrounded by a protein coat termed the pericentriolar material (PCM). Centrioles generally remain physically associated together (a phenomenon called centrosome cohesion), yet how this occurs in the absence of a bounding lipid membrane is unclear. One model posits that pericentriolar fibres formed from rootletin protein directly link centrioles, yet little is known about the structure, biophysical properties, or assembly kinetics of such fibres...
April 12, 2018: PLoS Biology
Wei Zhang, Wei He, Licong Peng, Ying Zhang, Jian-Wang Cai, Richard F L Evans, Qun Xiang Zhang, Zhao-Hua Cheng
The critical outcome of the interactions between light and nanostructured ferromagnetic film has been demonstrated that the ultrashort laser pulse can directly switch the magentic domains. It leads to the dawn of a new era for breaking the ultimate physical limit for the speed of magnetic switching and manipulation, which is relevant to current and future information storage. However, the fundamental understanding for the interactions between spins, electrons and lattices far from equilibrium induced by laser pulse is still lacking in the case of magnetic heterostructures with nanoscale domain configurations...
April 12, 2018: Nanotechnology
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