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https://www.readbyqxmd.com/read/28213842/determination-of-the-porosity-of-plga-microparticles-by-tracking-their-sedimentation-velocity-using-a-flow-imaging-microscope-flowcam
#1
A S Sediq, S K D Waasdorp, M R Nejadnik, M M C van Beers, J Meulenaar, R Verrijk, W Jiskoot
PURPOSE: To investigate whether particle sedimentation velocity tracking using a flow imaging microscope (FlowCAM) can be used to determine microparticle porosity. METHODS: Two different methods were explored. In the first method the sedimentation rate of microparticles was tracked in suspending media with different densities. The porosity was calculated from the average apparent density of the particles derived by inter- or extrapolation to the density of a suspending medium in which the sedimentation velocity was zero...
February 17, 2017: Pharmaceutical Research
https://www.readbyqxmd.com/read/28212705/detection-of-dna-damage-by-space-radiation-in-human-fibroblasts-flown-on-the-international-space-station
#2
Tao Lu, Ye Zhang, Michael Wong, Alan Feiveson, Ramona Gaza, Nicholas Stoffle, Huichen Wang, Bobby Wilson, Larry Rohde, Louis Stodieck, Fathi Karouia, Honglu Wu
Although charged particles in space have been detected with radiation detectors on board spacecraft since the discovery of the Van Allen Belts, reports on the effects of direct exposure to space radiation in biological systems have been limited. Measurement of biological effects of space radiation is challenging due to the low dose and low dose rate nature of the radiation environment, and due to the difficulty in distinguishing the radiation effects from microgravity and other space environmental factors. In astronauts, only a few changes, such as increased chromosome aberrations in their lymphocytes and early onset of cataracts, are attributed primarily to their exposure to space radiation...
February 2017: Life Sciences in Space Research
https://www.readbyqxmd.com/read/28212075/towards-photoplethysmography-based-estimation-of-instantaneous-heart-rate-during-physical-activity
#3
Delaram Jarchi, Alex Casson
OBJECTIVE: Recently numerous methods have been proposed for estimating average heart rate using photoplethysmography (PPG) during physical activity, overcoming the significant interference that motion causes in PPG traces. We propose a new algorithm framework for extracting instantaneous heart rate from wearable PPG and ECG signals to provide an estimate of heart rate variability during exercise. METHODS: For ECG signals we propose a new spectral masking approach which modifies a particle filter tracking algorithm, and for PPG signals constrains the instantaneous frequency obtained from the Hilbert transform to a region of interest around a candidate heart rate measure...
February 13, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28210618/an-optimized-procedure-for-the-site-directed-labeling-of-ngf-and-prongf-for-imaging-purposes
#4
Pierluigi Di Matteo, Mariantonietta Calvello, Stefano Luin, Laura Marchetti, Antonino Cattaneo
Neurotrophins are growth factors of fundamental importance for the development, survival and maintenance of different neuronal and non-neuronal populations. Over the years, the use of labeled neurotrophins has helped in the study of their biological functions, leading to a better understanding of the processes that regulate their transport, traffic, and signaling. However, the diverse and heterogeneous neurotrophin labeling strategies adopted so far have often led to poorly reproducible protocols and sometimes conflicting conclusions...
2017: Frontiers in Molecular Biosciences
https://www.readbyqxmd.com/read/28208719/micro-computed-tomography-detection-of-gold-nanoparticle-labelled-mesenchymal-stem-cells-in-the-rat-subretinal-layer
#5
Pooi Ling Mok, Sue Ngein Leow, Avin Ee-Hwan Koh, Hairul Harun Mohd Nizam, Suet Lee Shirley Ding, Chi Luu, Raduan Ruhaslizan, Hon Seng Wong, Wan Haslina Wan Abdul Halim, Min Hwei Ng, Ruszymah Binti Hj Idrus, Shiplu Roy Chowdhury, Catherine Mae-Lynn Bastion, Suresh Kumar Subbiah, Akon Higuchi, Abdullah A Alarfaj, Kong Yong Then
Mesenchymal stem cells are widely used in many pre-clinical and clinical settings. Despite advances in molecular technology; the migration and homing activities of these cells in in vivo systems are not well understood. Labelling mesenchymal stem cells with gold nanoparticles has no cytotoxic effect and may offer suitable indications for stem cell tracking. Here, we report a simple protocol to label mesenchymal stem cells using 80 nm gold nanoparticles. Once the cells and particles were incubated together for 24 h, the labelled products were injected into the rat subretinal layer...
February 8, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28208591/fusion-of-inertial-magnetic-sensor-measurements-and-map-information-for-pedestrian-tracking
#6
Shu-Di Bao, Xiao-Li Meng, Wendong Xiao, Zhi-Qiang Zhang
The wearable inertial/magnetic sensor based human motion analysis plays an important role in many biomedical applications, such as physical therapy, gait analysis and rehabilitation. One of the main challenges for the lower body bio-motion analysis is how to reliably provide position estimations of human subject during walking. In this paper, we propose a particle filter based human position estimation method using a foot-mounted inertial and magnetic sensor module, which not only uses the traditional zero velocity update (ZUPT), but also applies map information to further correct the acceleration double integration drift and thus improve estimation accuracy...
February 10, 2017: Sensors
https://www.readbyqxmd.com/read/28208318/microfield-dynamics-in-dense-hydrogen-plasmas-with-high-z-impurities
#7
Stefan P Hau-Riege, Jon Weisheit
We use large-scale classical molecular dynamics to determine microfield properties for several dense plasma mixtures. By employing quantum statistical potentials (QSPs) to regularize the Coulomb interaction, our simulations follow motions of electrons as well as ions for times long enough to track relaxation phenomena involving both types of particles. Coulomb coupling, relative to temperature, of different pairs of species in the hot, dense matter being simulated ranges from weak to strong. We first study the effect of such coupling differences, along with composition and QSP differences, on the roles of electrons and various mixture components in determining probability distributions of instantaneous, total microfields experienced by the ions...
January 2017: Physical Review. E
https://www.readbyqxmd.com/read/28201913/reaction-rates-for-reaction-diffusion-kinetics-on-unstructured-meshes
#8
Stefan Hellander, Linda Petzold
The reaction-diffusion master equation is a stochastic model often utilized in the study of biochemical reaction networks in living cells. It is applied when the spatial distribution of molecules is important to the dynamics of the system. A viable approach to resolve the complex geometry of cells accurately is to discretize space with an unstructured mesh. Diffusion is modeled as discrete jumps between nodes on the mesh, and the diffusion jump rates can be obtained through a discretization of the diffusion equation on the mesh...
February 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28201522/development-of-a-real-time-internal-and-external-marker-tracking-system-for-particle-therapy-a-phantom-study-using-patient-tumor-trajectory-data
#9
Junsang Cho, Wonjoong Cheon, Sanghee Ahn, Hyunuk Jung, Heesoon Sheen, Hee Chul Park, Youngyih Han
No abstract text is available yet for this article.
February 15, 2017: Journal of Radiation Research
https://www.readbyqxmd.com/read/28196962/spatial-and-temporal-analysis-of-alphavirus-replication-and-assembly-in-mammalian-and-mosquito-cells
#10
Joyce Jose, Aaron B Taylor, Richard J Kuhn
Sindbis virus (SINV [genus Alphavirus, family Togaviridae]) is an enveloped, mosquito-borne virus. Alphaviruses cause cytolytic infections in mammalian cells while establishing noncytopathic, persistent infections in mosquito cells. Mosquito vector adaptation of alphaviruses is a major factor in the transmission of epidemic strains of alphaviruses. Though extensive studies have been performed on infected mammalian cells, the morphological and structural elements of alphavirus replication and assembly remain poorly understood in mosquito cells...
February 14, 2017: MBio
https://www.readbyqxmd.com/read/28196148/from-the-track-to-the-ocean-using-flow-control-to-improve-marine-bio-logging-tags-for-cetaceans
#11
Giovani Fiore, Erik Anderson, C Spencer Garborg, Mark Murray, Mark Johnson, Michael J Moore, Laurens Howle, K Alex Shorter
Bio-logging tags are an important tool for the study of cetaceans, but superficial tags inevitably increase hydrodynamic loading. Substantial forces can be generated by tags on fast-swimming animals, potentially affecting behavior and energetics or promoting early tag removal. Streamlined forms have been used to reduce loading, but these designs can accelerate flow over the top of the tag. This non-axisymmetric flow results in large lift forces (normal to the animal) that become the dominant force component at high speeds...
2017: PloS One
https://www.readbyqxmd.com/read/28194311/tracking-the-virus-like-particles-of-macrobrachium-rosenbergii-nodavirus-in-insect-cells
#12
Ummi Fairuz Hanapi, Chean Yeah Yong, Zee Hong Goh, Noorjahan Banu Alitheen, Swee Keong Yeap, Wen Siang Tan
Macrobrachium rosenbergii nodavirus (MrNv) poses a major threat to the prawn industry. Currently, no effective vaccine and treatment are available to prevent the spread of MrNv. Its infection mechanism and localisation in a host cell are also not well characterised. The MrNv capsid protein (MrNvc) produced in Escherichia coli self-assembled into virus-like particles (VLPs) resembling the native virus. Thus, fluorescein labelled MrNvc VLPs were employed as a model to study the virus entry and localisation in Spodoptera frugiperda, Sf9 cells...
2017: PeerJ
https://www.readbyqxmd.com/read/28193017/single-particle-tracking-of-peptides-modified-nanocargo-on-lipid-membrane-revealing-bulk-mediated-diffusion
#13
Lin Wei, Zhongju Ye, Yueling Xu, Bo Chen, Edward S Yeung, Lehui Xiao
Understanding the detailed diffusion behavior of the nanocargo on lipid membrane can afford deep insight into the surface chemistry controlled translocation mechanism for the rational design of an efficient delivery system. By tracking the diffusion trajectory of transacting activator of transcription (TAT, a cell penetrating peptide) peptides-modified nanocargo on lipid membrane, bulk-mediated (intermittent hopping) diffusion was observed for the first time after a blended modification of TAT peptides and polyethylene glycol (PEG) molecules onto the nanoparticle surface...
December 20, 2016: Analytical Chemistry
https://www.readbyqxmd.com/read/28192902/concentration-normalized-electroanalytical-assaying-of-exosomal-markers
#14
Qian Li, George K Tofaris, Jason J Davis
Exosomes are both active in mediating intracellular communication and potentially present a potent cargo of disease biomarkers to an assay. The robust evaluation of exosomal markers could lead to a paradigm shift in clinical analysis and associated care. To date, much of this has been hindered by issues of sample preparation and assay signal-to-noise. We introduce here the use of ultrasensitive electrochemical impedance spectroscopy to quantify both external (tetraspanin) and internal (syntenin) exosome-specific markers...
February 10, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28192297/controlling-and-tracking-of-colloidal-nanostructures-through-two-photon-fluorescence
#15
Dipankar Mondal, Debabrata Goswami
Multiphoton absorbing dye-coated trapped spherical bead at the focal plane of femtosecond optical tweezers shows nonlinear optical (NLO) phenomena. One such NLO process of two-photon fluorescence (TPF) has been used for the background-free imaging of a femtosecond laser-trapping event. Due to the high peak powers of femtosecond laser pulses with low average powers, it is possible to not only trap single nanospheres, but encourage optically directed self-assembly. The TPF signatures of trapped particles show evidence of such a directed self-assembly process which, in turn, can provide information about the structural dynamics during the process of cluster formation...
October 7, 2016: Methods and Applications in Fluorescence
https://www.readbyqxmd.com/read/28181480/a-comparison-between-track-structure-condensed-history-monte-carlo-simulations-and-mird-cellular-s-values
#16
M A Tajik-Mansoury, H Rajabi, H Mozdarani
The S-value is a standard measure in cellular dosimetry. S-values are calculated by applying analytical methods or by Monte Carlo simulation. In Monte Carlo simulation, particles are either tracked individually event-by-event or close events are condensed and processed collectively in different steps. Both of these methods have been employed for estimation of cellular S-values, but there is no consistency between the published results. In the present paper, we used the Geant4-DNA track-structure physics model as the reference to estimate the cellular S-values...
March 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28177340/intracellular-nanoparticle-dynamics-affected-by-cytoskeletal-integrity
#17
Martha E Grady, Emmabeth Parrish, Matthew A Caporizzo, Sarah C Seeger, Russell J Composto, David M Eckmann
The cell interior is a crowded chemical space, which limits the diffusion of molecules and organelles within the cytoplasm, affecting the rates of chemical reactions. We provide insight into the relationship between non-specific intracellular diffusion and cytoskeletal integrity. Quantum dots entered the cell through microinjection and their spatial coordinates were captured by tracking their fluorescence signature as they diffused within the cell cytoplasm. Particle tracking revealed significant enhancement in the mobility of biocompatible quantum dots within fibrosarcoma cells versus their healthy counterparts, fibroblasts, as well as in actin destabilized fibroblasts versus untreated fibroblasts...
February 8, 2017: Soft Matter
https://www.readbyqxmd.com/read/28177301/tracking-short-term-biodistribution-and-long-term-clearance-of-spio-tracers-in-magnetic-particle-imaging
#18
Paul Keselman, Elaine Yu, Xinyi Zhou, Patrick Goodwill, Prashant Chandrasekharan, R Matthew Ferguson, Amit Khandhar, Scott Kemp, Kannan Krishnan, Bo Zheng, Steven Conolly
Magnetic Particle Imaging (MPI) is an emerging tracer-based medical imaging modality that images non-radioactive, kidney-safe superparamagnetic iron oxide (SPIO) tracers. MPI offers quantitative, high-contrast and high-SNR images, so MPI has exceptional promise for applications such as cell tracking, angiography, brain perfusion, cancer detection, traumatic brain injury and pulmonary imaging. In assessing MPI's utility for applications mentioned above, it is important to be able to assess tracer short-term biodistribution as well as long-term clearance from the body...
February 8, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28170101/torsion-estimation-of-particle-paths-through-porous-media-observed-by-in-situ-time-resolved-microtomography
#19
C Blankenburg, A Rack, C Daul, J Ohser
The torsion distribution of cell paths in two-phase flow of a cell suspension through a porous medium is an important quantity for chromatographic processes. It can be estimated from cell tracking in sequences of three-dimensional images of a suspension pumped through the medium, where the images are acquired by in-situ time-resolved microtomography using synchrotron radiation and inline phase contrast modus. This contribution presents a new method for estimating path torsion from discrete positions, where the estimation is based on an appropriate discretization of the differential-geometric formula of the torsion of a space curve...
February 7, 2017: Journal of Microscopy
https://www.readbyqxmd.com/read/28164999/high-resolution-traction-force-microscopy-on-small-focal-adhesions-improved-accuracy-through-optimal-marker-distribution-and-optical-flow-tracking
#20
Claude N Holenstein, Unai Silvan, Jess G Snedeker
The accurate determination of cellular forces using Traction Force Microscopy at increasingly small focal attachments to the extracellular environment presents an important yet substantial technical challenge. In these measurements, uncertainty regarding accuracy is prominent since experimental calibration frameworks at this size scale are fraught with errors - denying a gold standard against which accuracy of TFM methods can be judged. Therefore, we have developed a simulation platform for generating synthetic traction images that can be used as a benchmark to quantify the influence of critical experimental parameters and the associated errors...
February 6, 2017: Scientific Reports
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