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https://www.readbyqxmd.com/read/29353351/the-multiple-roles-of-titin-in-muscle-contraction-and-force-production
#1
REVIEW
Walter Herzog
Titin is a filamentous protein spanning the half-sarcomere, with spring-like properties in the I-band region. Various structural, signaling, and mechanical functions have been associated with titin, but not all of these are fully elucidated and accepted in the scientific community. Here, I discuss the primary mechanical functions of titin, including its accepted role in passive force production, stabilization of half-sarcomeres and sarcomeres, and its controversial contribution to residual force enhancement, passive force enhancement, energetics, and work production in shortening muscle...
January 20, 2018: Biophysical Reviews
https://www.readbyqxmd.com/read/29353082/3d-extrusion-printing-of-high-drug-loading-immediate-release-paracetamol-tablets
#2
Shaban A Khaled, Morgan R Alexander, Ricky D Wildman, Martin J Wallace, Sonja Sharpe, Jae Yoo, Clive J Roberts
The manufacture of immediate release high drug loading paracetamol oral tablets was achieved using an extrusion based 3D printer from a premixed water based paste formulation. The 3D printed tablets demonstrate that a very high drug (paracetamol) loading formulation (80% w/w) can be printed as an acceptable tablet using a method suitable for personalisation and distributed manufacture. Paracetamol is an example of a drug whose physical form can present challenges to traditional powder compression tableting...
January 15, 2018: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/29352977/paclitaxel-inhibited-lysozyme-fibrillation-by-increasing-colloidal-stability-through-formation-of-off-pathway-oligomers
#3
Ehsan Kachooei, Faroogh Mozaffarian, Fariba Khodagholi, Payam Sedeghi, Leila Karami, Atiyeh Ghasemi, Elham Vahdat, Ali Akbar Saboury, Nader Sheibani, Ali Akbar Moosavi-Movahedi
Protein fibrillation is a challenging issue in medicine, causing many diseases, and an impediment to pharmaceutics and protein industry. Many chemicals, especially polyphenol compounds and aromatic small molecules, have been widely used as an effective strategy to combat protein fibril formation. Hence, understanding mechanisms of fibrillation inhibition and contributing forces in this process are significant. In this study, the inhibitory effect of paclitaxel on lysozyme fibrillation was investigated with respect to thermal and colloidal stability...
January 15, 2018: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/29352789/hydrodynamic-relaxations-in-dissipative-particle-dynamics
#4
J S Hansen, Michael L Greenfield, Jeppe C Dyre
This paper studies the dynamics of relaxation phenomena in the standard dissipative particle dynamics (DPD) model [R. D. Groot and P. B. Warren, J. Chem. Phys. 107, 4423 (1997)]. Using fluctuating hydrodynamics as the framework of the investigation, we focus on the collective transverse and longitudinal dynamics. It is shown that classical hydrodynamic theory predicts the transverse dynamics at relatively low temperatures very well when compared to simulation data; however, the theory predictions are, on the same length scale, less accurate for higher temperatures...
January 21, 2018: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29352330/relationship-between-power-duration-parameters-and-mechanical-and-anthropometric-properties-of-the-thigh-in-elite-cyclists
#5
Mehdi Kordi, Campbell Menzies, Len Parker Simpson
PURPOSE: The curvature constant (W') and asymptote (critical power; CP) of the power-duration relationship are important parameters for explaining cycling performance. Short-duration endurance cycling events rely more heavily on the W'; however, the full mechanistic underpinning of this parameter is yet to be determined. Evidence suggests both muscle volume and muscle strength may contribute to the magnitude of W'. Therefore, the present study investigated the relationship between power-duration parameters (CP and W') and (1) anthropometric and (2) mechanical properties of thigh muscles in a sample of elite cyclists...
January 19, 2018: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/29352267/differential-susceptibility-of-striatal-hippocampal-and-cortical-neurons-to-caspase-6
#6
Anastasia Noël, Libin Zhou, Bénédicte Foveau, P Jesper Sjöström, Andréa C LeBlanc
Active cysteinyl protease Caspase-6 is associated with early Alzheimer and Huntington diseases. Higher entorhinal cortex and hippocampal Caspase-6 levels correlate with lower cognitive performance in aged humans. Caspase-6 induces axonal degeneration in human primary neuron cultures and causes inflammation and neurodegeneration in mouse hippocampus, and age-dependent memory impairment. To assess whether Caspase-6 causes damage to another neuronal system, a transgenic knock-in mouse overexpressing a self-activated form of Caspase-6 five-fold in the striatum, the area affected in Huntington disease, and 2...
January 19, 2018: Cell Death and Differentiation
https://www.readbyqxmd.com/read/29352192/full-wave-electromagnetic-optimisation-of-corrugated-metallic-reectors-using-a-multigrid-approach
#7
Gökhan Karaova, Aşkın Altınoklu, Özgür Ergül
A multigrid optimisation strategy is introduced to design passive metallic reflectors with corrugated shapes. The strategy is based on using genetic algorithms at multiple grids and shaping the metal sheets, starting from coarse details to fine tunings. This corresponds to a systematic expansion of the related optimisation space, which is explored more efficiently in comparison to a brute-force optimisation without using grid. By employing the multilevel fast multipole algorithm to analyse the electromagnetic problems corresponding to optimisation trials, we obtain accurately designed reflectors that provide focussing abilities with very high performances at single and multiple locations...
January 19, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29352144/pressure-assisted-enhancement-in-superconducting-properties-of-fe-substituted-nbse2-single-crystal
#8
Manikandan Krishnan, Rukshana Pervin, Kalai Selvan Ganesan, Kannan Murugesan, Govindaraj Lingannan, Akshay Kumar Verma, Parasharam M Shirage, Arumugam Sonachalam
The impact of hydrostatic pressure (P) up to 1 GPa on T c , J c and the nature of the pinning mechanism in FexNbSe2 single crystals have been investigated within the framework of the collective theory. We found that the pressure can induce a transition from the regime where pinning is controlled by spatial variation in the critical transition temperature (δT c ) to the regime controlled by spatial variation in the mean free path (δℓ). Furthermore, T c and low field J c are slightly induced, although the J c drops more rapidly at high fields than at ambient P...
January 19, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29351995/enucleated-cells-reveal-differential-roles-of-the-nucleus-in-cell-migration-polarity-and-mechanotransduction
#9
David M Graham, Tomas Andersen, Lisa Sharek, Gunes Uzer, Katheryn Rothenberg, Brenton D Hoffman, Janet Rubin, Martial Balland, James E Bear, Keith Burridge
The nucleus has long been postulated to play a critical physical role during cell polarization and migration, but that role has not been defined or rigorously tested. Here, we enucleated cells to test the physical necessity of the nucleus during cell polarization and directed migration. Using enucleated mammalian cells (cytoplasts), we found that polarity establishment and cell migration in one dimension (1D) and two dimensions (2D) occur without the nucleus. Cytoplasts directionally migrate toward soluble (chemotaxis) and surface-bound (haptotaxis) extracellular cues and migrate collectively in scratch-wound assays...
January 19, 2018: Journal of Cell Biology
https://www.readbyqxmd.com/read/29351723/mitochondrial-uncoupling-proteins-subtle-regulators-of-cellular-redox-signaling
#10
Petr Jezek, Blanka Holendová, Keith D Garlid, Martin Jaburek
SIGNIFICANCE: Mitochondria are the energetic, metabolic, redox and information signaling centers of the cell. Substrate pressure, mitochondrial network dynamics and cristae morphology state are integrated by the protonmotive force Δp or its potential component, ΔΨ, which are attenuated by proton backflux into the matrix, termed uncoupling. The mitochondrial uncoupling proteins (UCP1-5) play an eminent role in the regulation of each of the above aspects, being involved in numerous physiological events including redox signaling...
January 19, 2018: Antioxidants & Redox Signaling
https://www.readbyqxmd.com/read/29351477/mathematical-analysis-of-circadian-disruption-and-metabolic-re-entrainment-of-hepatic-gluconeogenesis-the-intertwining-entraining-roles-of-light-and-feeding
#11
Seul-A Bae, Ioannis P Androulakis
The circadian rhythms influence the metabolic activity from molecular level to tissue, organ, and host level. Disruption of the circadian rhythms manifest to the host's health as metabolic syndromes including obesity, diabetes, and elevated plasma glucose, eventually leading to cardiovascular diseases. Therefore, it is imperative to understand the mechanism behind the relationship between circadian rhythms and metabolism. To start answering this question, we propose a semi-mechanistic mathematical model to study the effect of circadian disruption on hepatic gluconeogenesis in humans...
January 9, 2018: American Journal of Physiology. Endocrinology and Metabolism
https://www.readbyqxmd.com/read/29351163/comparison-of-the-force-velocity-and-power-time-curves-between-the-concentric-only-and-eccentric-concentric-bench-press-exercises
#12
Alejandro Pérez-Castilla, Paul Comfort, John J McMahon, Francisco Luis Pestaña-Melero, Amador García-Ramos
The aim of this study was to compare the temporal and mechanical variables between the concentric-only and eccentric-concentric bench press (BP) variants. Twenty-one men (age: 22.0±4.2 years, body mass: 73.4±7.7 kg, height: 177.2±8.0 cm; one-repetition maximum [1RM]: 1.12±0.12 kg⋅kg) were evaluated during the concentric-only and eccentric-concentric BP variants using 80% 1RM. Temporal (concentric phase duration, propulsive phase duration, and time to reach the maximum values of force, velocity, and power) and mechanical variables (force, velocity, and power), determined using a linear velocity transducer, were compared between both BP variants...
January 17, 2018: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/29350911/a-programmable-dna-origami-platform-for-organizing-intrinsically-disordered-nucleoporins-within-nanopore-confinement
#13
Patrick D Ellis Fisher, Qi Shen, Bernice Akpinar, Luke K Davis, Kenny Kwok Hin Chung, David Baddeley, Andela Saric, Thomas J Melia, Bart W Hoogenboom, Chenxiang Lin, C Patrick Lusk
Nuclear pore complexes (NPCs) form gateways that control molecular exchange between the nucleus and the cytoplasm. They impose a diffusion barrier to macromolecules and enable the selective transport of nuclear transport receptors with bound cargo. The underlying mechanisms that establish these permeability properties remain to be fully elucidated, but require unstructured nuclear pore proteins rich in Phe-Gly (FG)-repeat domains of different types, such as FxFG and GLFG. While physical modeling and in vitro approaches have provided a framework for explaining how the FG network contributes to the barrier and transport properties of the NPC, it remains unknown whether the number and/or the spatial positioning of different FG-domains along a cylindrical, ~40 nm diameter transport channel contributes to their collective properties and function...
January 19, 2018: ACS Nano
https://www.readbyqxmd.com/read/29350233/stacking-faults-in-zr-fe-cr-2-laves-structured-secondary-phase-particle-in-zircaloy-4-alloy
#14
Chengze Liu, Geping Li, Fusen Yuan, Fuzhou Han, Yingdong Zhang, Hengfei Gu
Stacking faults (SFs) in secondary phase particles (SPPs), which generally crystallize in the Laves phase in Zircaloy-4 (Zr-4) alloy, have been frequently observed by researchers. However, few investigations on the nano-scale structure of SFs have been carried out. In the present study, an SF containing C14 structured SPP, which located at grain boundaries (GBs) in the α-Zr matrix, was chosen to be investigated, for its particular substructure as well as location, aiming to reveal the nature of the SFs in the SPPs in Zr-4 alloy...
January 19, 2018: Nanoscale
https://www.readbyqxmd.com/read/29350192/size-dependent-young-s-modulus-in-zno-nanowires-with-strong-surface-atomic-bonds
#15
Shiwen Fan, Sheng Bi, Qikun Li, Qinglei Guo, Junshan Liu, Zhongliang Ouyang, Chengming Jiang, Jinhui Song
Mechanical properties of size-dependent nanowires are important in nano-electro-mechanical systems (NEMS), and have attracted much research interest. It is desperate to characterize the size effect of nanowires at atmosphere directly to broaden its practical application instead of in high vacuum situation as reported previously. In this study, we systematically studied the Young's modulus of vertical ZnO nanowires at atmosphere. The diameters range from 48nm to 287 nm, with resonance method by non-contact atomic force microscopy (AFM)...
January 19, 2018: Nanotechnology
https://www.readbyqxmd.com/read/29350184/chirality-in-molecular-collision-dynamics
#16
Andrea Lombardi, Federico Palazzetti
Chirality is a phenomenon that permeates the natural world, with implications for atomic and molecular physics, for fundamental forces and for the mechanisms at the origin of the early evolution of life and biomolecular homochirality. The manifestations of chirality in chemistry and biochemistry are numerous, the striking ones being chiral recognition and asymmetric synthesis with important applications in molecular sciences and in industrial and pharmaceutical chemistry. Chiral discrimination phenomena, due to the existence of two enantiomeric forms, very well known in the case of interaction with light, but still nearly disregarded in molecular collision studies...
January 19, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29350182/the-role-of-eeg-in-the-diagnosis-and-classification-of-the-epilepsy-syndromes-a-tool-for-clinical-practice-by-the-ilae-neurophysiology-task-force-part-2
#17
Michalis Koutroumanidis, Alexis Arzimanoglou, Roberto Caraballo, Sushma Goyal, Anna Kaminska, Pramote Laoprasert, Hirokazu Oguni, Guido Rubboli, William Tatum, Pierre Thomas, Eugen Trinka, Luca Vignatelli, Solomon L Moshé
The concept of epilepsy syndromes, introduced in 1989, was defined as "clusters of signs and symptoms customarily occurring together". Definition of epilepsy syndromes based on electro-clinical features facilitated clinical practice and, whenever possible, clinical research in homogeneous groups of patients with epilepsies. Progress in the fields of neuroimaging and genetics made it rapidly clear that, although crucial, the electro-clinical description of epilepsy syndromes was not sufficient to allow much needed development of targeted therapies and a better understanding of the underlying pathophysiological mechanisms of seizures...
December 1, 2017: Epileptic Disorders: International Epilepsy Journal with Videotape
https://www.readbyqxmd.com/read/29350015/-application-of-finite-element-method-in-spinal-biomechanics
#18
REVIEW
Qiang Liu, Jun Zhang, Shu-Chun Sun, Fei Wang
The finite element model is one of the most important methods in study of modern spinal biomechanics, according to the needs to simulate the various states of the spine, calculate the stress force and strain distribution of the different groups in the state, and explore its principle of mechanics, mechanism of injury, and treatment effectiveness. In addition, in the study of the pathological state of the spine, the finite element is mainly used in the understanding the mechanism of lesion location, evaluating the effects of different therapeutic tool, assisting and completing the selection and improvement of therapeutic tool, in order to provide a theoretical basis for the rehabilitation of spinal lesions...
February 25, 2017: Zhongguo Gu Shang, China Journal of Orthopaedics and Traumatology
https://www.readbyqxmd.com/read/29349631/promoter-analysis-of-the-fish-gene-of-slow-cardiac-type-myosin-heavy-chain-implicated-in-specification-of-muscle-fiber-types
#19
Shigeharu Kinoshita, Saltuk Bugrahan Ceyhun, Asaduzzamann Md, Bhuiyan Sharmin Siddique, Dadasaheb B Akolkar, Shuichi Asakawa, Shugo Watabe
Vertebrate skeletal muscles consist of heterogeneous tissues containing various types of muscle fibers, where specification of the fiber type is crucial for muscle development. Fish are an attractive experimental model to study the mechanisms of such fiber type specification because of the separated localization of slow and fast muscles in the trunk myotome. We examined regulation of expression of the torafugu gene of slow/cardiac-type myosin heavy chain, MYH M5 , and isolated an operational promoter in order to force its tissue-specific expression across different fish species via the transgenic approach in zebrafish and medaka...
January 18, 2018: Fish Physiology and Biochemistry
https://www.readbyqxmd.com/read/29349450/complex-patchy-colloids-shaped-from-deformable-seed-particles-through-capillary-interactions
#20
V Meester, D J Kraft
We investigate the mechanisms underlying the reconfiguration of random aggregates of spheres through capillary interactions, the so-called "colloidal recycling" method, to fabricate a wide variety of patchy particles. We explore the influence of capillary forces on clusters of deformable seed particles by systematically varying the crosslink density of the spherical seeds. Spheres with a poorly crosslinked polymer network strongly deform due to capillary forces and merge into large spheres. With increasing crosslink density and therefore rigidity, the shape of the spheres is increasingly preserved during reconfiguration, yielding patchy particles of well-defined shape for up to five spheres...
January 19, 2018: Soft Matter
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