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Intermittent mechanical strain

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https://www.readbyqxmd.com/read/29721087/resveratrol-counteracts-bone-loss-via-mitofilin-mediated-osteogenic-improvement-of-mesenchymal-stem-cells-in-senescence-accelerated-mice
#1
Ya-Jie Lv, Yi Yang, Bing-Dong Sui, Cheng-Hu Hu, Pan Zhao, Li Liao, Ji Chen, Li-Qiang Zhang, Tong-Tao Yang, Shao-Feng Zhang, Yan Jin
Rational: Senescence of mesenchymal stem cells (MSCs) and the related functional decline of osteogenesis have emerged as the critical pathogenesis of osteoporosis in aging. Resveratrol (RESV), a small molecular compound that safely mimics the effects of dietary restriction, has been well documented to extend lifespan in lower organisms and improve health in aging rodents. However, whether RESV promotes function of senescent stem cells in alleviating age-related phenotypes remains largely unknown. Here, we intend to investigate whether RESV counteracts senescence-associated bone loss via osteogenic improvement of MSCs and the underlying mechanism...
2018: Theranostics
https://www.readbyqxmd.com/read/29715605/effects-of-ultrasonic-vibration-on-the-compression-of-pure-titanium
#2
Tao Liu, Jun Lin, Yanjin Guan, Zhendong Xie, Lihua Zhu, Jiqiang Zhai
The technology of ultrasonic vibration assisted plastic forming possesses a great many merits, such as reducing the deformation resistance and friction, as well as improving the surface quality of parts. In this study, the ultrasonic vibration assisted compression tests were carried out on pure titanium in order to improve its formability. The results indicating that the ultrasonic vibration had no effort on elastic deformation, and the temperature of material only increased by 6 °C after compression with applying the ultrasonic vibration...
April 24, 2018: Ultrasonics
https://www.readbyqxmd.com/read/29448439/modeling-the-complexity-of-acoustic-emission-during-intermittent-plastic-deformation-power-laws-and-multifractal-spectra
#3
Jagadish Kumar, G Ananthakrishna
Scale-invariant power-law distributions for acoustic emission signals are ubiquitous in several plastically deforming materials. However, power-law distributions for acoustic emission energies are reported in distinctly different plastically deforming situations such as hcp and fcc single and polycrystalline samples exhibiting smooth stress-strain curves and in dilute metallic alloys exhibiting discontinuous flow. This is surprising since the underlying dislocation mechanisms in these two types of deformations are very different...
January 2018: Physical Review. E
https://www.readbyqxmd.com/read/29358150/micromechanisms-of-fatigue-crack-growth-in-polycarbonate-polyurethane-time-dependent-and-hydration-effects
#4
Audrey C Ford, Hannah Gramling, Samuel C Li, Jessica V Sov, Amrita Srinivasan, Lisa A Pruitt
Polycarbonate polyurethane has cartilage-like, hygroscopic, and elastomeric properties that make it an attractive material for orthopedic joint replacement application. However, little data exists on the cyclic loading and fracture behavior of polycarbonate polyurethane. This study investigates the mechanisms of fatigue crack growth in polycarbonate polyurethane with respect to time dependent effects and conditioning. We studied two commercially available polycarbonate polyurethanes, Bionate® 75D and 80A. Tension testing was performed on specimens at variable time points after being removed from hydration and variable strain rates...
March 2018: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/29344659/degree-of-endplate-chondrocyte-degeneration-in-different-tension-regions-during-mechanical-stimulation
#5
Yongming Xu, Shujuan Xu, Zhi Gao, Liang Xiao, Fei Xiao, Hongguang Xu, Xiaoling Zhang
The aim of this study was to explore the degree of degeneration of endplate chondrocytes in different tension regions induced by intermittent cyclic mechanical tension (ICMT) in vitro. Rat endplate chondrocytes were harvested and treated with 10% ICMT for 8 h/day with a frequency of 0.5 Hz. A cartilage degeneration model was induced using an FX‑5000T cell strain‑loading system. The experiment was divided into the central region and the peripheral region, according to the contact area between the loading post and the six‑well flexible silicone rubber BioFlex plates...
January 16, 2018: Molecular Medicine Reports
https://www.readbyqxmd.com/read/29306866/mechanical-stress-potentiates-the-differentiation-of-periodontal-ligament-stem-cells-into-keratocytes
#6
Jialin Chen, Wei Zhang, Ludvig J Backman, Peyman Kelk, Patrik Danielson
AIMS: To explore the role of corneal-shaped static mechanical strain on the differentiation of human periodontal ligament stem cells (PDLSCs) into keratocytes and the possible synergistic effects of mechanics and inducing medium. METHODS: PDLSCs were exposed to 3% static dome-shaped mechanical strain in a Flexcell Tension System for 3 days and 7 days. Keratocyte phenotype was determined by gene expression of keratocyte markers. Keratocyte differentiation (inducing) medium was introduced in the Flexcell system, either continuously or intermittently combined with mechanical stimulation...
April 2018: British Journal of Ophthalmology
https://www.readbyqxmd.com/read/29199462/role-of-genetics-in-peripheral-arterial-disease-outcomes-significance-of-limb-salvage-quantitative-locus-1-genes
#7
Emmanuel Okeke, Ayotunde O Dokun
Peripheral artery disease is a major health care problem with significant morbidity and mortality. Humans with peripheral artery disease exhibit two major and differential clinical manifestations - intermittent claudication and critical limb ischemia. Individuals with intermittent claudication or critical limb ischemia have overlapping risk factors and objective measures of blood flow. Hence, we hypothesized that variation in genetic make-up may be an important determinant in the severity of peripheral artery disease...
January 2018: Experimental Biology and Medicine
https://www.readbyqxmd.com/read/29160864/clonal-expansion-behind-a-marine-diatom-bloom
#8
Maria Valeria Ruggiero, Domenico D'Alelio, Maria Immacolata Ferrante, Mariano Santoro, Laura Vitale, Gabriele Procaccini, Marina Montresor
Genetic diversity is what selection acts on, thus shaping the adaptive potential of populations. We studied micro-evolutionary patterns of the key planktonic diatom Pseudo-nitzschia multistriata at a long-term sampling site over 2 consecutive years by genotyping isolates with 22 microsatellite markers. We show that both sex and vegetative growth interplay in shaping intraspecific diversity. We document a brief but massive demographic and clonal expansion driven by strains of the same mating type. The analysis of an extended data set (6 years) indicates that the genetic fingerprint of P...
November 21, 2017: ISME Journal
https://www.readbyqxmd.com/read/29032456/silver-loaded-chitosan-coating-as-an-integrated-approach-to-face-titanium-implant-associated-infections-analytical-characterization-and-biological-activity
#9
Stefania Cometa, Maria A Bonifacio, Federico Baruzzi, Silvia de Candia, Maria M Giangregorio, Lorena C Giannossa, Manuela Dicarlo, Monica Mattioli-Belmonte, Luigia Sabbatini, Elvira De Giglio
The present work focuses on the idea to prevent and/or inhibit the colonization of implant surfaces by microbial pathogens responsible for post-operative infections, adjusting antimicrobial properties of the implant surface prior to its insertion. An antibacterial coating based on chitosan and silver was developed by electrodeposition techniques on poly(acrylic acid)-coated titanium substrates. When a silver salt was added during the chitosan deposition step, a stable and scalable silver incorporation was achieved...
December 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28985491/tanshinone-iia-ameliorated-endothelial-dysfunction-in-rats-with-chronic-intermittent-hypoxia
#10
Lingling Chen, Qiu-Hong Guo, Yue Chang, Ya-Shuo Zhao, Ai-Ying Li, En-Sheng Ji
Chronic intermittent hypoxia (CIH) during repetitive airflow cessations may cause endothelial dysfunction. Tanshinone IIA (Tan IIA) has been used to treat various circulatory disturbance-related diseases because of its pharmacological actions, including vasodilation. However, the mechanism of the effect of its vasodilation is not well established. The objective of this study was to explore the effect of Tan IIA in endothelium-dependent contracting factors and endothelin receptors in aortic endothelial dysfunction in CIH rats...
June 30, 2017: Cardiovascular Pathology: the Official Journal of the Society for Cardiovascular Pathology
https://www.readbyqxmd.com/read/28980724/minimal-mechanical-load-and-tissue-culture-conditions-preserve-native-cell-phenotype-and-morphology-in-tendon-a-novel-ex-vivo-mouse-explant-model
#11
Stefania L Wunderli, Jonas Widmer, Niklaus Amrein, Jasper Foolen, Unai Silvan, Olivier Leupin, Jess G Snedeker
Appropriate mechanical load is essential for tendon homeostasis and optimal tissue function. Due to technical challenges in achieving physiological mechanical loads in experimental tendon model systems, the research community still lacks well-characterized models of tissue homeostasis and physiological relevance. Toward this urgent goal, we present and characterize a novel ex vivo murine tail tendon explant model. Mouse tail tendon fascicles were extracted and cultured for 6 days in a load-deprived environment or in a custom-designed bioreactor applying low magnitude mechanical load (intermittent cycles to 1% strain, at 1 Hz) in serum-free tissue culture...
October 5, 2017: Journal of Orthopaedic Research: Official Publication of the Orthopaedic Research Society
https://www.readbyqxmd.com/read/28975256/wireless-implantable-sensor-for-noninvasive-longitudinal-quantification-of-axial-strain-across-rodent-long-bone-defects
#12
Brett S Klosterhoff, Keat Ghee Ong, Laxminarayanan Krishnan, Kevin M Hetzendorfer, Young-Hui Chang, Mark G Allen, Robert E Guldberg, Nick J Willett
Bone development, maintenance, and regeneration are remarkably sensitive to mechanical cues. Consequently, mechanical stimulation has long been sought as a putative target to promote endogenous healing after fracture. Given the transient nature of bone repair, tissue-level mechanical cues evolve rapidly over time after injury and are challenging to measure noninvasively. The objective of this work was to develop and characterize an implantable strain sensor for noninvasive monitoring of axial strain across a rodent femoral defect during functional activity...
November 1, 2017: Journal of Biomechanical Engineering
https://www.readbyqxmd.com/read/28827428/from-slow-to-fast-faulting-recent-challenges-in-earthquake-fault-mechanics
#13
S Nielsen
Faults-thin zones of highly localized shear deformation in the Earth-accommodate strain on a momentous range of dimensions (millimetres to hundreds of kilometres for major plate boundaries) and of time intervals (from fractions of seconds during earthquake slip, to years of slow, aseismic slip and millions of years of intermittent activity). Traditionally, brittle faults have been distinguished from shear zones which deform by crystal plasticity (e.g. mylonites). However such brittle/plastic distinction becomes blurred when considering (i) deep earthquakes that happen under conditions of pressure and temperature where minerals are clearly in the plastic deformation regime (a clue for seismologists over several decades) and (ii) the extreme dynamic stress drop occurring during seismic slip acceleration on faults, requiring efficient weakening mechanisms...
September 28, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/28754642/symptomatic-thoracic-nerve-root-herniation-into-an-extradural-arachnoid-cyst-case-report-and-review-of-the-literature
#14
Nagesh C Shanbhag, Ruurd F Duyff, Rob J M Groen
BACKGROUND: Spinal extradural arachnoid cysts (SEACs) are relatively rare and usually asymptomatic. They preferentially are situated in the thoracic extradural space and almost always dorsal. SEACs may present with back pain and/or cord compression symptoms. Needle aspiration, needle fenestration, or open surgical resection/fenestration have been reported as treatment modalities. CASE DESCRIPTION: We present a 35-year-old woman who complained of radiating pain from the right lower thoracic region of her back toward the right inguinal region, which was aggravated upon defecation and straining...
October 2017: World Neurosurgery
https://www.readbyqxmd.com/read/28474178/household-aggregation-of-staphylococcus-aureus-by-clonal-complex-and-methicillin-resistance-profiles-in-starr-county-texas
#15
C L Hanis, K E Garrett, H T Essigmann, D A Robinson, S M Gunter, A G Nyitray, E L Brown
Staphylococcus aureus is one of the most common causes of skin and soft tissue infections in health-care and community settings, but transmission of S. aureus in community-based populations is incompletely understood. S. aureus carriage phenotypes (persistent, intermittent, and non-carriers) were determined for households from Starr County, TX. Nasal swabs were collected from a cohort of 901 residents and screened for the presence of S. aureus. Isolated strains were spa-typed and assigned to clonal complexes...
October 2017: European Journal of Clinical Microbiology & Infectious Diseases
https://www.readbyqxmd.com/read/28436748/disruption-of-tetr-type-regulator-aden-by-mobile-genetic-element-confers-elevated-virulence-in-acinetobacter-baumannii
#16
Rajagopalan Saranathan, Sudhakar Pagal, Ajit R Sawant, Archana Tomar, M Madhangi, Suresh Sah, Annapurna Satti, K P Arunkumar, K Prashanth
Acinetobacter baumannii is an important human pathogen and considered as a major threat due to its extreme drug resistance. In this study, the genome of a hyper-virulent MDR strain PKAB07 of A. baumannii isolated from an Indian patient was sequenced and analyzed to understand its mechanisms of virulence, resistance and evolution. Comparative genome analysis of PKAB07 revealed virulence and resistance related genes scattered throughout the genome, instead of being organized as an island, indicating the highly mosaic nature of the genome...
October 3, 2017: Virulence
https://www.readbyqxmd.com/read/28427342/intermittent-parathyroid-hormone-pth-promotes-cementogenesis-and-alleviates-the-catabolic-effects-of-mechanical-strain-in-cementoblasts
#17
Yuyu Li, Zhiai Hu, Chenchen Zhou, Yang Xu, Li Huang, Xin Wang, Shujuan Zou
BACKGROUND: External root resorption, commonly starting from cementum, is a severe side effect of orthodontic treatment. In this pathological process and repairing course followed, cementoblasts play a significant role. Previous studies implicated that parathyroid hormone (PTH) could act on committed osteoblast precursors to promote differentiation, and inhibit apoptosis. But little was known about the role of PTH in cementoblasts. The purpose of this study was to investigate the effects of intermittent PTH on cementoblasts and its influence after mechanical strain treatment...
April 20, 2017: BMC Cell Biology
https://www.readbyqxmd.com/read/28322540/rapid-recovery-double-cross-linking-hydrogel-with-stable-mechanical-properties-and-high-resilience-triggered-by-visible-light
#18
Longxiang Zhu, Jianhui Qiu, Eiichi Sakai, Kazushi Ito
The designed tough hydrogels, depending on energy dissipation mechanism, possess excellent biocompatibility, stimuli-responsiveness, and outstanding mechanical properties. However, the application of hydrogels is greatly limited in actuators and sensors for the lack of instantaneous recovery and resilience. In this work, we synthesized a double cross-linking poly(acrylic acid) hydrogel via a simple, one-pot, visible-light-trigger polymerization, with carboxymethyl cellulose as initiator and the first cross-linker, N,N'-methylene bis(acrylamide) (MBA) as the second cross-linker...
April 5, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28110193/effects-of-polyphenol-compounds-melanin-on-nafld-nash-prevention
#19
Natalia Belemets, Nazarii Kobyliak, Oleksandr Virchenko, Tetyana Falalyeyeva, Tsyryuk Olena, Petro Bodnar, Oleksiy Savchuk, Tetyana Galenova, Martin Caprnda, Luis Rodrigo, Lubomir Skladany, Delian Delev, Radka Opatrilova, Peter Kruzliak, Tetyana Beregova, Lyudmyla Ostapchenko
BACKGROUND: One of the pathogenic mechanisms of the progression non-alcoholic liver disease (NAFLD) to nonalcoholic steatohepatitis (NASH) is the accumulation of reactive oxygen species (ROS). So, antioxidant therapy is necessary for successful treatment of the liver injury. We have paid attention to melanin produced by yeast Nadsoniella nigra strain X-1 as novel antioxidant and anti-inflammatory agents with low toxicity. In current study we aimed to investigate the preventive effect of melanin on the monosodium glutamate (MSG) induced NAFLD model in rats...
April 2017: Biomedicine & Pharmacotherapy, Biomédecine & Pharmacothérapie
https://www.readbyqxmd.com/read/28025300/linking-scales-in-sea-ice-mechanics
#20
Jérôme Weiss, Véronique Dansereau
Mechanics plays a key role in the evolution of the sea ice cover through its control on drift, on momentum and thermal energy exchanges between the polar oceans and the atmosphere along cracks and faults, and on ice thickness distribution through opening and ridging processes. At the local scale, a significant variability of the mechanical strength is associated with the microstructural heterogeneity of saline ice, however characterized by a small correlation length, below the ice thickness scale. Conversely, the sea ice mechanical fields (velocity, strain and stress) are characterized by long-ranged (more than 1000 km) and long-lasting (approx...
February 13, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
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