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https://www.readbyqxmd.com/read/28433578/a-novel-device-for-continuous-long-term-electroencephalogram-recording-and-drug-administration-in-mice-with-a-nice-powerful-and-sophisticated-wired-system
#1
Shigeru Watanabe, Masanori Saito, Masaki Soma, Hitoshi Miyaoka, Masami Takahashi
BACKGROUND: To elucidate mechanisms of epileptogenesis and epileptic maturation, and to develop new AEDs, it is indispensable to administer various drugs and to examine their effects on EEG over a long period of observation. NEW METHOD: We constructed a device for the continuous measurement of electroencephalography (EEG) and the infusion of anti-epileptic drugs over a prolonged period of time in moving mice. The system includes a slip ring and a swivel to prevent twisting of the recording cable and infusion tube, respectively...
April 19, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/28433391/mechanisms-of-anterior-posterior-stability-of-the-knee-joint-under-load-bearing
#2
Ryan J Reynolds, Peter S Walker, John Buza
The anterior-posterior (AP) stability of the knee is an important aspect of functional performance. Studies have shown that the stability increases when compressive loads are applied, as indicated by reduced laxity, but the mechanism has not been fully explained. A test rig was designed which applied combinations of AP shear and compressive forces, and measured the AP displacements relative to the neutral position. Five knees were evaluated at compressive loads of 0, 250, 500, and 750N, with the knee at 15° flexion...
April 7, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28433389/comparison-of-methodologies-to-assess-muscle-co-contraction-during-gait
#3
H Souissi, R Zory, J Bredin, P Gerus
The aim of this study was to compare co-contraction index (CCI) computed from muscle moments to different co-activation indexes (Co-Act) derived from EMG data at the ankle and the knee joint during gait. An EMG-driven model was used to estimate muscle moments during over-ground walking gait at a self-selected velocity from twelve healthy subjects. The CCI calculated from muscle moments was compared with three Co-Acts estimated from the normalized EMG data. The co-activation methods produced lower values than the CCI during the first double-support and the swing phase at the ankle joint and during the stance phase at the knee joint...
April 9, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28433388/magnetic-resonance-and-diffusion-tensor-imaging-analyses-indicate-heterogeneous-strains-along-human-medial-gastrocnemius-fascicles-caused-by-submaximal-plantar-flexion-activity
#4
Agah Karakuzu, Uluç Pamuk, Cengizhan Ozturk, Burak Acar, Can A Yucesoy
Sarcomere length changes are central to force production and excursion of skeletal muscle. Previous modeling indicates non-uniformity of that if mechanical interaction of muscle with its surrounding muscular and connective tissues is taken into account. Hence, quantifying length changes along the fascicles of activated human muscle in vivo is crucial, but this is lacking due to technical complexities. Combining magnetic resonance imaging deformation analyses and diffusion tensor imaging tractography, the aim was to test the hypothesis that submaximal plantar flexion activity at 15% MVC causes heterogeneous length changes along the fascicles of human medial gastrocnemius (GM) muscle...
April 9, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28433387/how-do-rocker-soled-shoes-influence-the-knee-adduction-moment-in-people-with-knee-osteoarthritis-an-analysis-of-biomechanical-mechanisms
#5
Elizabeth G Madden, Crystal O Kean, Tim V Wrigley, Kim L Bennell, Rana S Hinman
The primary objective was to examine mechanisms behind previously observed changes in the knee adduction moment (KAM) with rocker-soled shoes, in participants sub-grouped according to whether they experienced an immediate decrease, or increase, in peak KAM. In subgroups where frontal plane knee ground reaction force (GRF) lever-arm emerged as a significant predictor, a secondary aim was to examine biomechanical factors that contributed to change in this parameter. Thirty individuals with symptomatic, radiographic knee osteoarthritis (OA) underwent 3D gait analysis in unstable rocker-soled shoes and non-rocker-soled shoes...
April 9, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28433020/introducing-the-mean-field-approximation-to-cdft-mmpol-method-statistically-converged-equilibrium-and-nonequilibrium-free-energy-calculation-for-electron-transfer-reactions-in-condensed-phases
#6
Hiroshi Nakano, Hirofumi Sato
A new theoretical method to study electron transfer reactions in condensed phases is proposed by introducing the mean-field approximation into the constrained density functional theory/molecular mechanical method with a polarizable force field (CDFT/MMpol). The method enables us to efficiently calculate the statistically converged equilibrium and nonequilibrium free energies for diabatic states in an electron transfer reaction by virtue of the mean field approximation that drastically reduces the number of CDFT calculations...
April 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28432999/effect-of-intra-oral-aging-on-t%C3%A2-m-phase-transformation-microstructure-and-mechanical-properties-of-y-tzp-dental-ceramics
#7
Luciana Meireles Miragaya, Renato Bastos Guimarães, Rodrigo Othávio de Assunção E Souza, Glauco Dos Santos Botelho, José Guilherme Antunes Guimarães, Eduardo Moreira da Silva
The aim of the present study was to evaluate the influence of intra-oral aging on the tetragonal-to-monoclinic (t→m) phase transformation of two Y-TZP dental ceramics - Lava Frame (Frame) and Lava Plus (Plus) - and determine the impact of this response on their microstructures and mechanical properties: flexural strength, Young's modulus, microhardness and fracture toughness. Standardized ceramic specimens were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM)...
April 13, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28432984/cigarette-smoke-extract-counteracts-atheroprotective-effects-of-high-laminar-flow-on-endothelial-function
#8
Sindy Giebe, Natalia Cockcroft, Katherine Hewitt, Melanie Brux, Anja Hofmann, Henning Morawietz, Coy Brunssen
Tobacco smoking and hemodynamic forces are key stimuli in the development of endothelial dysfunction and atherosclerosis. High laminar flow has an atheroprotective effect on the endothelium and leads to a reduced response of endothelial cells to cardiovascular risk factors compared to regions with disturbed or low laminar flow. We hypothesize that the atheroprotective effect of high laminar flow could delay the development of endothelial dysfunction caused by cigarette smoking. Primary human endothelial cells were stimulated with increasing dosages of aqueous cigarette smoke extract (CSEaq)...
April 7, 2017: Redox Biology
https://www.readbyqxmd.com/read/28432960/molecular-dynamic-simulations-on-tkx-50-rdx-cocrystal
#9
Shuling Xiong, Shusen Chen, Shaohua Jin
Dihydroxylammonium 5,5'-bistetrazole-1,1'-diolate (TKX-50) is a newly synthesized energetic material with excellent comprehensive properties. Cyclotrimethylenetrinitramine (RDX) is currently one of the most widely used energetic materials in the world. TKX-50 and RDX supercell models and TKX-50/RDX cocrystal model were constructed based on their crystal cell parameters and the formation mechanism of cocrystal, respectively, then they were simulated by molecular dynamics (MD) simulations. The maximum trigger bond (NNO2) length(Lmax), binding energy (Ebind), radial distribution function (RDF), cohesive energy density(CED) and mechanical properties were simulated at different temperatures based on the simulated equilibrium structures of the models...
March 19, 2017: Journal of Molecular Graphics & Modelling
https://www.readbyqxmd.com/read/28432883/sagittal-plane-joint-kinetics-during-stair-ascent-in-patients-with-peripheral-arterial-disease-and-intermittent-claudication
#10
Stephanie L King, Natalie Vanicek, Thomas D O'Brien
Stair negotiation poses a substantial physical demand on the musculoskeletal system and this challenging task can place individuals at risk of falls. Peripheral arterial disease (PAD) can cause intermittent claudication (IC) pain in the calf and results in altered gait mechanics during level walking. However, whether those with PAD-IC adopt alternate strategies to climb stairs is unknown. Twelve participants with PAD-IC (six bilateral and six unilateral) and 10 healthy controls were recruited and instructed to ascend a five-step staircase whilst 3D kinematic data of the lower-limbs were recorded synchronously with kinetic data from force plates embedded into the staircase on steps two and three...
March 28, 2017: Gait & Posture
https://www.readbyqxmd.com/read/28432615/fabrication-physicochemical-characterization-and-performance-evaluation-of-biodegradable-polymeric-microneedle-patch-system-for-enhanced-transcutaneous-flux-of-high-molecular-weight-therapeutics
#11
Viral Shah, Bijaya Krushna Choudhury
A revolutionary paradigm shift is being observed currently, towards the use of therapeutic biologics for disease management. The present research was focused on designing an efficient dosage form for transdermal delivery of α-choriogonadotropin (high molecular weight biologic), through biodegradable polymeric microneedles. Polyvinylpyrrolidone-based biodegradable microneedle arrays loaded with high molecular weight polypeptide, α-choriogonadotropin, were fabricated for its systemic delivery via transdermal route...
April 21, 2017: AAPS PharmSciTech
https://www.readbyqxmd.com/read/28432448/resistance-to-radial-expansion-limits-muscle-strain-and-work
#12
E Azizi, A R Deslauriers, N C Holt, C E Eaton
The collagenous extracellular matrix (ECM) of skeletal muscle functions to transmit force, protect sensitive structures, and generate passive tension to resist stretch. The mechanical properties of the ECM change with age, atrophy, and neuromuscular pathologies, resulting in an increase in the relative amount of collagen and an increase in stiffness. Although numerous studies have focused on the effect of muscle fibrosis on passive muscle stiffness, few have examined how these structural changes may compromise contractile performance...
April 21, 2017: Biomechanics and Modeling in Mechanobiology
https://www.readbyqxmd.com/read/28432420/sex-differences-in-neuromuscular-function-after-repeated-eccentric-contractions-of-the-knee-extensor-muscles
#13
Andrea Lee, Jake Baxter, Claire Eischer, Matt Gage, Sandra Hunter, Tejin Yoon
PURPOSE: This study examined the mechanisms for force and power reduction during and up to 48 h after maximal eccentric contractions of the knee extensor muscles in young men and women. METHODS: 13 men (22.8 ± 2.6 years) and 13 women (21.6 ± 2.2 years) performed 150 maximal effort eccentric contractions (5 sets of 30) with the knee extensor muscles at 60° s(-1). Maximal voluntary isometric contractions (MVIC) and maximal voluntary concentric contractions (MVCC) were performed before and after the 150 eccentric contractions...
April 21, 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/28432261/ccm2-and-pak4-act-downstream-of-atrial-natriuretic-peptide-signaling-to-promote-cell-spreading
#14
Koichi Miura, Takashi Nojiri, Yoshiharu Akitake, Koji Ando, Shigetomo Fukuhara, Masahiro Zenitani, Toru Kimura, Jun Hino, Mikiya Miyazato, Hiroshi Hosoda, Kenji Kangawa
Atrial natriuretic peptide (ANP) is a cardiac hormone released by the atrium in response to stretching forces. Via its receptor, guanylyl cyclase-A (GC-A), ANP maintains cardiovascular homeostasis by exerting diuretic, natriuretic, and hypotensive effects mediated in part by endothelial cells. Both in vivo and in vitro , ANP enhances endothelial barrier function by reducing RhoA activity and reorganizing the actin cytoskeleton. We established mouse endothelial cells that stably express GC-A, and used them to analyze the molecular mechanisms responsible for actin reorganization...
April 21, 2017: Biochemical Journal
https://www.readbyqxmd.com/read/28432118/molecular-basis-for-exercise-induced-fatigue-the-importance-of-strictly-controlled-cellular-ca-2-handling
#15
Arthur J Cheng, Nicolas Place, Håkan Westerblad
The contractile function of skeletal muscle declines during intense or prolonged physical exercise, that is, fatigue develops. Skeletal muscle fibers fatigue acutely during highly intense exercise when they have to rely on anaerobic metabolism. Early stages of fatigue involve impaired myofibrillar function, whereas decreased Ca(2+) release from the sarcoplasmic reticulum (SR) becomes more important in later stages. SR Ca(2+) release can also become reduced with more prolonged, lower intensity exercise, and it is then related to glycogen depletion...
April 21, 2017: Cold Spring Harbor Perspectives in Medicine
https://www.readbyqxmd.com/read/28431969/crfr1-in-the-ventromedial-caudate-putamen-modulates-acute-stress-enhanced-expression-of-cocaine-locomotor-sensitization
#16
Shuli Liu, Zhiyan Wang, Yijing Li, Xiaowei Sun, Feifei Ge, Mingda Yang, Xinjuan Wang, Na Wang, Junkai Wang, Cailian Cui
Repeated exposure to psychostimulants induces a long-lasting enhancement of locomotor activity called behavioral sensitization, which is often reinforced by stress after drug withdrawal. The mechanisms underlying these phenomena remain elusive. Here we explored the effects of acute stress 3 or 14 days after the cessation of chronic cocaine treatment on the expression of locomotor sensitization induced by a cocaine challenge in rats and the key brain region and molecular mechanism underlying the phenomenon. A single session of forced swimming, as an acute stress (administered 2 days after the cessation of cocaine), significantly enhanced the expression of cocaine locomotor sensitization 14 days after the final cocaine injection (challenge at 12 days after acute stress) but not 3 days after the cessation of cocaine (challenge at 1 day after acute stress)...
April 18, 2017: Neuropharmacology
https://www.readbyqxmd.com/read/28431962/structural-basis-chemical-driving-forces-and-biological-implications-of-flavones-as-cu-ii-ionophores
#17
Fang Dai, Wen-Jing Yan, Yu-Ting Du, Xia-Zhen Bao, Xiu-Zhuang Li, Bo Zhou
A main biochemical property of cancer cells, compared with normal cells, is altered redox status including increased levels of copper to maintain their malignant phenotypes. Thus, increasing copper accumulation, by using ionophores, to disrupt abnormal redox homeostasis of cancer cells may be an important anticancer strategy. Naturally occurring molecules with extraordinarily diverse chemical scaffolds are an important source of inspiration for developing copper ionophores. Dietary flavonoids are well-characterized copper chelators and show cancer chemopreventive potential, but their ionophoric role for redox-active copper and the related biological implications have remained unknown...
April 18, 2017: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/28431939/modulation-of-hat-activity-by-the-brca2n372hvariation-is-a-novel-mechanism-of-paclitaxel-resistance-in-breast-cancer-cell-lines
#18
Woo Sun Kwon, Sun Young Rha, Hei-Cheul Jeung, Tae Soo Kim, Hyun Cheol Chung
Paclitaxel stabilizes microtubule polymerization, enhances microtubule assembly, andG2/M arrests, leading to cell death. Paclitaxel resistance has been attributed to a variety of mechanisms. In the present study, we define a new resistance mechanism to paclitaxel based onBRCA2variation. Chemo-sensitivity to paclitaxel based on the variations was compared. Restoration of paclitaxel sensitivity was induced indirectly with combined treatment of paclitaxel and HDAC inhibitor. Variant and wild type of BRCA2 clones were obtained from wild and variant cells, respectively...
April 18, 2017: Biochemical Pharmacology
https://www.readbyqxmd.com/read/28431748/a-benchtop-biorobotic-platform-for-in-vitro-observation-of-muscle-tendon-dynamics-with-parallel-mechanical-assistance-from-an-elastic-exoskeleton
#19
Benjamin D Robertson, Siddarth Vadakkeveedu, Gregory S Sawicki
We present a novel biorobotic framework comprised of a biological muscle-tendon unit (MTU) mechanically coupled to a feedback controlled robotic environment simulation that mimics in vivo inertial/gravitational loading and mechanical assistance from a parallel elastic exoskeleton. Using this system, we applied select combinations of biological muscle activation (modulated with rate-coded direct neural stimulation) and parallel elastic assistance (applied via closed-loop mechanical environment simulation) hypothesized to mimic human behavior based on previously published modeling studies...
March 21, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28431618/muscle-strength-and-power-in-persons-with-multiple-sclerosis-a-systematic-review-and-meta-analysis
#20
REVIEW
Mlk Jørgensen, U Dalgas, I Wens, L G Hvid
BACKGROUND: Multiple sclerosis (MS) is a chronic disease in the central nervous system which causes a number of physical symptoms including impairments of muscle mechanical function (muscle strength, muscle power and explosive muscle strength (~rate of force development, RFD)). However, a full overview of the existing knowledge regarding muscle mechanical function in persons with MS (PwMS) is still pending. OBJECTIVES: To systematically review 1) the psychometric properties of isokinetic dynamometry testing in PwMS, and 2) studies comparing muscle mechanical function in PwMS to matched healthy controls (HC)...
May 15, 2017: Journal of the Neurological Sciences
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