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Contrast dynamics

Sonya Youngju Park, Claudia Zacharias, Caitlyn Harrison, Richard E Fan, Christian Kunder, Negin Hatami, Frederik Giesel, Pejman Ghanouni, Bruce Daniel, Andreas M Loening, Geoffrey A Sonn, Andrei Iagaru
Purpose To report the results of dual-time-point gallium 68 (68 Ga) prostate-specific membrane antigen (PSMA)-11 positron emission tomography (PET)/magnetic resonance (MR) imaging prior to prostatectomy in patients with intermediate- or high-risk cancer. Materials and Methods Thirty-three men who underwent conventional imaging as clinically indicated and who were scheduled for radical prostatectomy with pelvic lymph node dissection were recruited for this study. A mean dose of 4.1 mCi ± 0.7 (151.7 MBq ± 25...
May 16, 2018: Radiology
Pragya Mishra, Nisha Singh, Ajay Jain, Neha Jain, Vagish Mishra, Pushplatha G, Kiran P Sandhya, Nagendra Kumar Singh, Vandna Rai
Rice, a staple food crop, is often subjected to drought and salinity stresses thereby limiting its yield potential. Since there is a cross talk between these abiotic stresses, identification of common and/or overlapping regulatory elements is pivotal for generating rice cultivars that showed tolerance towards them. Analysis of the gene interaction network (GIN) facilitates identifying the role of individual genes and their interactions with others that constitute important molecular determinants in sensing and signaling cascade governing drought and/or salinity stresses...
2018: Bioinformation
Zachary M Sherman, Dipanjan Ghosh, James W Swan
Directed assembly of dielectric and paramagnetic nanoparticles can be used to synthesize diverse functional materials that polarize in response to an externally applied electric or magnetic field. However, theories capable of predicting the self-assembled states are lacking. In the proposed work, we develop a complete thermodynamic description of such assemblies for spherical nanoparticles. We show how an important physical feature of these types of particles, mutual polarization, sculpts the free energy landscape and has a remarkably strong influence on the nature of the self-assembled states...
May 21, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Serge D Zemerov, Benjamin W Roose, Mara L Greenberg, Yanfei Wang, Ivan J Dmochowski
Cryptophane-based biosensors are promising agents for the ultrasensitive detection of biomedically relevant targets via 129Xe NMR. Dynamic light scattering revealed that cryptophanes form water-soluble aggregates of tens-to-hundreds of nanometers in size. Acridine orange fluorescence quenching assays allowed quantitation of aggregation state, with critical concentration rang-ing from 200 to 600 nM, depending on the cryptophane species in solution. Addition of excess carbonic anhydrase (CA) pro-tein target to a benzenesulfonamide-functionalized cryptophane biosensor (C8B) led to C8B disaggregation and produced the expected 1:1 C8B-CA complex...
May 21, 2018: Analytical Chemistry
Sophie E Heethuis, Lucas Goense, Peter S N van Rossum, Alicia S Borggreve, Stella Mook, Francine E M Voncken, Annemarieke Bartels-Rutten, Berthe M P Aleman, Richard van Hillegersberg, Jelle P Ruurda, Gert J Meijer, Jan J W Lagendijk, Astrid L H M W van Lier
PURPOSE: To explore the potential benefit and complementary value of a multiparametric approach using diffusion-weighted (DW-) and dynamic contrast-enhanced (DCE-) magnetic resonance imaging (MRI) for prediction of response to neoadjuvant chemoradiotherapy (nCRT) in esophageal cancer. MATERIAL AND METHODS: Forty-five patients underwent both DW-MRI and DCE-MRI prior to nCRT (pre), during nCRT (week 2-3) (per) and after completion of nCRT, but prior to esophagectomy (post)...
May 21, 2018: Acta Oncologica
Kyle J Schnitzenbaumer, Gordana Dukovic
Surface ligand modification of colloidal semiconductor nanocrystals has been widely used as a means of controlling photoexcited state generation, relaxation, and coupling to the environment. While progress has been made in understanding how surface ligand modification affects the behavior of excitonic states, less is known about the influence of surface ligand modification on phonon behavior, which impacts relaxation dynamics and transport phenomena. In this work we compare the dynamics of optical and acoustic phonons in CdTe quantum dots (QDs), CdTe/CdSe core/shell QDs capped with octadecylphosphonic acid ligands, and CdTe QDs capped with Se2- to ascertain how ligand exchange from native aliphatic ligands to single-atom Se2- ligands affects phonon behavior...
May 21, 2018: Nano Letters
Prabir Khatua, Sanjoy Bandyopadhyay
It is believed that the self-assembly of amyloid beta (Aβ) peptides in the brain is the cause of Alzheimer's disease. Atomistic molecular dynamics simulations of aqueous solutions of Aβ protofilaments of different sizes at room temperature have been carried out to explore the dynamic properties of water confined within the core and at the exterior surface of the protofilaments. Attempts have been made to understand how the non-uniform distortion of the protofilaments associated with their structural crossover influences the diffusivity and the hydrogen bonding environment of the confined water molecules...
May 21, 2018: Physical Chemistry Chemical Physics: PCCP
A Park Williams, Benjamin I Cook, Jason E Smerdon, Daniel A Bishop, Richard Seager, Justin S Mankin
The fall 2016 drought in the southeastern United States (SE US) appeared exceptional based on its widespread impacts, but the current monitoring framework that only extends from 1979-present does not readily facilitate evaluation of soil-moisture anomalies in a centennial context. A new method to extend monthly gridded soil-moisture estimates back to 1895 is developed, indicating that since 1895, October-November 2016 soil moisture (0-200 cm) in the SE US was likely the second lowest on record, behind 1954...
October 27, 2017: Journal of Geophysical Research. Atmospheres: JGR
Stefan Karlowsky, Angela Augusti, Johannes Ingrisch, Roland Hasibeder, Markus Lange, Sandra Lavorel, Michael Bahn, Gerd Gleixner
Mountain grasslands have recently been exposed to substantial changes in land use and climate and in the near future will likely face an increased frequency of extreme droughts. To date, how the drought responses of carbon (C) allocation, a key process in the C cycle, are affected by land-use changes in mountain grassland is not known.We performed an experimental summer drought on an abandoned grassland and a traditionally managed hay meadow and traced the fate of recent assimilates through the plant-soil continuum...
May 2018: Journal of Ecology
Simon Hastreiter, Stavroula Skylaki, Dirk Loeffler, Andreas Reimann, Oliver Hilsenbeck, Philipp S Hoppe, Daniel L Coutu, Konstantinos D Kokkaliaris, Michael Schwarzfischer, Konstantinos Anastassiadis, Fabian J Theis, Timm Schroeder
Embryonic stem cells (ESCs) display heterogeneous expression of pluripotency factors such as Nanog when cultured with serum and leukemia inhibitory factor (LIF). In contrast, dual inhibition of the signaling kinases GSK3 and MEK (2i) converts ESC cultures into a state with more uniform and high Nanog expression. However, it is so far unclear whether 2i acts through an inductive or selective mechanism. Here, we use continuous time-lapse imaging to quantify the dynamics of death, proliferation, and Nanog expression in mouse ESCs after 2i addition...
May 10, 2018: Stem Cell Reports
Chiho Tokunaga, Shonosuke Matsushita, Hiroaki Sakamoto, Kazuyuki Hyodo, Misao Kubota, Kenkichi Tanioka, Yuji Hiramatsu
Background Increased pulmonary blood flow (PBF) and shear stress may provoke irreversible vascular remodeling, yet invasive visualization of the microvasculature complicates monitoring. A non-invasive imaging methodology would therefore safely provide mechanistic insights into the progression of high PBF-induced vascular remodeling. Purpose To establish a novel microvasculature visualization method using synchrotron radiation pulmonary microangiography (SRPA) that can also calculate PBF velocity in vivo. Material and Methods A high PBF rat model was established by making a fistula between the abdominal aorta and inferior vena cava...
January 1, 2018: Acta Radiologica
Hyeonglim Seo, Ikjang Choi, Nicholas Whiting, Jingzhe Hu, Quy Son Luu, Shivanand Pudakalakatti, Caitlin McCowan, Yaewon Kim, Niki Zacharias, Seunghyun Lee, Pratip Bhattacharya, Youngbok Lee
Porous silicon nanoparticles have recently garnered attention as potentially-promising biomedical platforms for drug delivery and medical diagnostics. Here, we demonstrate porous silicon nanoparticles as contrast agents for ²⁹Si magnetic resonance imaging. Size-controlled porous silicon nanoparticles were synthesized by magnesiothermic reduction of silica nanoparticles and were surface activated for further functionalization. Particles were hyperpolarized via dynamic nuclear polarization to enhance their ²⁹Si MR signals; the particles demonstrated long ²⁹Si spin-lattice relaxation (T₁) times (~ 25 mins), which suggests potential applicability for medical imaging...
May 20, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
P Monsalve, S Ren, G Triolo, L Vazquez, A D Henderson, M Kostic, P Gordon, W J Feuer, V Porciatti
PURPOSE: To investigate within-test variability of the steady-state PERG (SS-PERG). METHODS: SS-PERGs were recorded in response to black-white horizontal gratings (1.6 cycles/deg, 98% contrast, 15.63 reversals/s, LED display, 25 deg square field, 800 cd/sqm mean luminance) using skin electrodes. PERG and noise (± reference) signals were averaged over 1024 epochs (~ 2.2 min) and Fourier analyzed to retrieve SS-PERG amplitude and phase. SS-PERGs were split into 16 partial averages (samples) of 64 epochs each, and corresponding amplitudes and phases combined in polar coordinates to assess their dispersion (within-test variability)...
May 19, 2018: Documenta Ophthalmologica. Advances in Ophthalmology
Nicole Wake, Hersh Chandarana, Henry Rusinek, Koji Fujimoto, Linda Moy, Daniel K Sodickson, Sungheon Gene Kim
INTRODUCTION: Pharmacokinetic parameters derived from dynamic contrast-enhanced MRI (DCE-MRI) data are sensitive to acquisition and post-processing techniques, which makes it difficult to compare results obtained using different methods. In particular, one of the most important factors affecting estimation of model parameters is how to convert MRI signal intensities to contrast agent concentration. The purpose of our study was to quantitatively compare a linear signal-to-concentration conversion (LC) as an approximation and a non-linear conversion (NLC) based on the MRI signal equation, in terms of the accuracy and precision of the pharmacokinetic parameters in T1 -weighted DCE-MRI...
May 16, 2018: Magnetic Resonance Imaging
Sameer Shakeel Ansari, Imtiyaz Yousuf, Farukh Arjmand, Mohammad Khursheed Siddiqi, Saeeda Naqvi
The intermolecular interaction of flufenamic acid (Hfluf) with two model proteins i.e., hemoglobin and lysozyme was explored using fluorescence, UV-vis, circular dichroism, DLS, and molecular docking techniques. The corroborative spectroscopic techniques suggested efficient binding of Hfluf to both the proteins. The S-V plot in Hb-Hfluf system showed positive deviation highlighting the presence of both static and dynamic quenching. Hence, ground state complex model and sphere of action quenching model were used for the study...
May 16, 2018: International Journal of Biological Macromolecules
Emilie Lévêque, Aude Lacourt, Danièle Luce, Marie-Pierre Sylvestre, Pascal Guénel, Isabelle Stücker, Karen Leffondré
OBJECTIVE: To estimate the impact of intensity of both smoking and occupational exposure to asbestos on the risk of lung cancer throughout the whole exposure history. METHODS: Data on 2026 male cases and 2610 male controls came from the French ICARE (Investigation of occupational and environmental causes of respiratory cancers) population-based, case-control study. Lifetime smoking history and occupational history were collected from standardised questionnaires and face-to-face interviews...
May 18, 2018: Occupational and Environmental Medicine
Magdalena Blom, Katarina Reis, Pontus Aspenström
The atypical Rho GTPase RhoD has previously been shown to have a major impact on the organization and function of the actin filament system. However, when first discovered, RhoD was found to regulate endosome trafficking and dynamics and we therefore sought to investigate this regulation in more detail. We found that exogenously expressed RhoD in human fibroblasts localized to vesicles and the plasma membrane and that the active GTP-bound conformation was required for the plasma membrane localization but not for vesicle localization...
May 16, 2018: European Journal of Cell Biology
Akshay Bhatnagar, Anupam Gupta, Dhrubaditya Mitra, Rahul Pandit
We present an extensive numerical study of the time irreversibility of the dynamics of heavy inertial particles in three-dimensional, statistically homogeneous, and isotropic turbulent flows. We show that the probability density function (PDF) of the increment, W(τ), of a particle's energy over a time scale τ is non-Gaussian, and skewed toward negative values. This implies that, on average, particles gain energy over a period of time that is longer than the duration over which they lose energy. We call this slow gain and fast loss...
March 2018: Physical Review. E
Ilia Kaminker, Songi Han
Dynamic nuclear polarization (DNP) takes center stage in nuclear magnetic resonance (NMR) as a tool to amplify its signal by orders of magnitude through the transfer of polarization from electron to nuclear spins. In contrast to modern NMR and electron paramagnetic resonance (EPR) that extensively rely on pulses for spin manipulation in the time domain, the current mainstream DNP technology exclusively relies on monochromatic continuous wave (CW) irradiation. This study introduces arbitrary phase shaped pulses that constitute a train of coherent chirp pulses in the time domain at 200 GHz (7 Tesla) to dramatically enhance the saturation bandwidth and DNP performance compared to CW DNP, yielding up to 500-fold in NMR signal enhancements...
May 18, 2018: Journal of Physical Chemistry Letters
Urna Basu, Laurent Helden, Matthias Krüger
Nonlinear response theory, in contrast to linear cases, involves (dynamical) details, and this makes application to many-body systems challenging. From the microscopic starting point we obtain an exact response theory for a small number of coarse-grained degrees of freedom. With it, an extrapolation scheme uses near-equilibrium measurements to predict far-from-equilibrium properties (here, second order responses). Because it does not involve system details, this approach can be applied to many-body systems...
May 4, 2018: Physical Review Letters
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