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Mechanical loading

Decao Niu, Xiaobo Yuan, Arianne J Cease, Haiyan Wen, Chunping Zhang, Hua Fu, James J Elser
Increasing atmospheric nitrogen (N) deposition may affect plant biodiversity, subsequently altering ecosystem stability. While a few studies have explored how simulated N deposition affects community stability and its underlying mechanisms, the experimental levels of N addition used are usually higher than current and future N deposition rates. Thus, their results could produce highly uncertain predictions of ecosystem function, especially if the responses to N deposition are nonlinear. We conducted a manipulative experiment that simulated elevated atmospheric N deposition with several N addition levels to evaluate the effect of N deposition on ecosystem stability and its underlying mechanisms in a semiarid grassland in northern China...
October 17, 2017: Science of the Total Environment
Axel S Koopman, Idsart Kingma, Gert S Faber, Jonas Bornmann, Jaap H van Dieën
Mechanical loading of the spine has been shown to be an important risk factor for the development of low-back pain. Inertial motion capture (IMC) systems might allow measuring lumbar moments in realistic working conditions, and thus support evaluation of measures to reduce mechanical loading. As the number of sensors limits applicability, the objective of this study was to investigate the effect of the number of sensors on estimates of L5S1 moments. Hand forces, ground reaction forces (GRF) and full-body kinematics were measured using a gold standard (GS) laboratory setup...
October 12, 2017: Journal of Biomechanics
Andrew S Michalski, W Brent Edwards, Steven K Boyd
Quantitative computed tomography has been posed as an alternative imaging modality to investigate osteoporosis. We examined the influence of computed tomography convolution back-projection reconstruction kernels on the analysis of bone quantity and estimated mechanical properties in the proximal femur. Eighteen computed tomography scans of the proximal femur were reconstructed using both a standard smoothing reconstruction kernel and a bone-sharpening reconstruction kernel. Following phantom-based density calibration, we calculated typical bone quantity outcomes of integral volumetric bone mineral density, bone volume, and bone mineral content...
October 17, 2017: Journal of Clinical Densitometry
Kari A Duck, Ian A Simpson, James R Connor
Many critical metabolic functions in the brain require adequate and timely delivery of iron. However, most studies when considering brain iron uptake have ignored the iron requirements of the endothelial cells that form the blood-brain barrier (BBB). Moreover, current models of BBB iron transport do not address regional regulation of brain iron uptake or how neurons, when adapting to metabolic demands, can acquire more iron. In this study, we demonstrate that both iron-poor transferrin (apo-Tf) and the iron chelator, deferoxamine, stimulate release of iron from iron-loaded endothelial cells in an in vitro BBB model...
October 17, 2017: Biochemical and Biophysical Research Communications
Md Jasim Uddin, Harvinder Singh Gill
We have recently developed pollen grains (PGs) as a unique method to deliver vaccines orally. Extensive chemical processing ensures allergen-free pollen microcapsules that can be loaded with vaccine antigens. Successful oral vaccine delivery has been previously demonstrated by us in a mouse model. However, the underlying mechanisms that help the processed PGs to achieve this goal were not fully understood. In this study, we wanted to understand the effects of chemically processed ragweed pollen (Ambrosia elatior) on the innate immune system...
October 17, 2017: Journal of Controlled Release: Official Journal of the Controlled Release Society
Roopa Hebbandi Nanjundappa, Francesca Ronchi, Jinguo Wang, Xavier Clemente-Casares, Jun Yamanouchi, Channakeshava Sokke Umeshappa, Yang Yang, Jesús Blanco, Helena Bassolas-Molina, Azucena Salas, Hamza Khan, Robyn M Slattery, Madeleine Wyss, Catherine Mooser, Andrew J Macpherson, Laura K Sycuro, Pau Serra, Derek M McKay, Kathy D McCoy, Pere Santamaria
The gut microbiota contributes to the development of normal immunity but, when dysregulated, can promote autoimmunity through various non-antigen-specific effects on pathogenic and regulatory lymphocytes. Here, we show that an integrase expressed by several species of the gut microbial genus Bacteroides encodes a low-avidity mimotope of the pancreatic β cell autoantigen islet-specific glucose-6-phosphatase-catalytic-subunit-related protein (IGRP206-214). Studies in germ-free mice monocolonized with integrase-competent, integrase-deficient, and integrase-transgenic Bacteroides demonstrate that the microbial epitope promotes the recruitment of diabetogenic CD8+ T cells to the gut...
October 19, 2017: Cell
Yaqian Li, Xiaojun Yan, Wei Liu, Lyu Zhou, Zhifeng You, Yanan Du
To upgrade traditional 2D cell culture to 3D cell culture, we have integrated microfabrication with cryogelation technology to produce macroporous microscale cryogels (microcryogels), which can be loaded with a variety of cell types to form 3D microtissues. Herein, we present the protocol to fabricate versatile 3D microtissues and their applications in regenerative therapy and drug screening. Size and shape-controllable microcryogels can be fabricated on an array chip, which can be harvested off-chip as individual cell-loaded carriers for injectable regenerative therapy or be further assembled on-chip into 3D microtissue arrays for high-throughput drug screening...
October 4, 2017: Journal of Visualized Experiments: JoVE
Michael A Monn, Jarod Ferreira, Jianzhe Yang, Haneesh Kesari
Many load bearing biological structures (LBBSs)-such as feather rachises and spicules-are small (<1 mm) but not microscopic. Measuring the flexural behavior of these LBBSs is important for understanding the origins of their remarkable mechanical functions. We describe a protocol for performing three-point bending tests using a custom-built mechanical testing device that can measure forces ranging from 10(-5) to 10(1) N and displacements ranging from 10(-7) to 10(-2) m. The primary advantage of this mechanical testing device is that the force and displacement capacities can be easily adjusted for different LBBSs...
October 11, 2017: Journal of Visualized Experiments: JoVE
Elbay Malikmammadov, Tugba Endogan Tanir, Aysel Kiziltay, Vasif Hasirci, Nesrin Hasirci
Biodegradable polymers have met withan increasing demand in medical usage over the last decades. One of such polymers is poly(ε-caprolactone) (PCL), whichis a polyester that has been widely used in tissue engineering field for its availability, relatively inexpensive price and suitability for modification. Its chemical and biological properties, physicochemical state, degradability and mechanical strengthcan be adjusted, and therefore,it can be usedunderharsh mechanical, physical and chemical conditions without significant loss of its properties...
October 20, 2017: Journal of Biomaterials Science. Polymer Edition
M Dupraz, G Beutier, T W Cornelius, G Parry, Z Ren, S Labat, M-I Richard, G A Chahine, O Kovalenko, M De Boissieu, E Rabkin, M Verdier, O Thomas
Structural quality and stability of nanocrystals are fundamental problems that bear important consequences for the performances of small-scale devices. Indeed, at the nanoscale, their functional properties are largely influenced by elastic strain and depend critically on the presence of crystal defects. It is thus of prime importance to be able to monitor, by noninvasive means, the stability of the microstructure of nano-objects against external stimuli such as mechanical load. Here we demonstrate the potential of Bragg coherent diffraction imaging for such measurements, by imaging in 3D the evolution of the microstructure of a nanocrystal exposed to in situ mechanical loading...
October 20, 2017: Nano Letters
Di Chen, Dmitry Kolomenskiy, Toshiyuki Nakata, Hao Liu
In many flying insects, forewings and hindwings are coupled mechanically to achieve flapping flight synchronously while being driven by action of the forewings. How the forewings and hindwings as well as their morphologies contribute to aerodynamic force production and flight control remains unclear yet. Here we demonstrate that the forewings can produce most of the aerodynamic forces even with the hindwings removed through a computational fluid dynamic study of three revolving insect wing models, which are identical to the wing morphologies and Reynolds numbers of hawkmoth (Manduca sexta), bumblebee (Bombus ignitus) and fruitfly (Drosophila melanogaster)...
October 20, 2017: Bioinspiration & Biomimetics
Dong Mei Mei, Baodong Zhao, Hao Xu, Yanhui Wang
BACKGROUND: There is no data available on the long-term outcomes of a rooted, platform-switched, microthreaded implant with a sandblasted, large-grid, and acid-etched surface. PURPOSE: This prospective, longitudinal study evaluated the clinical and radiographic outcomes of rooted, platform-switched, microthreaded and sandblasted, large-grid, and acid-etched (SLA) surface implants for 5 years. MATERIALS AND METHODS: Sixty implants were placed in sixty patients with partially edentulous maxillae or mandibles...
October 20, 2017: Clinical Implant Dentistry and related Research
Bohayra Mortazavi, Aurélien Lherbier, Zheyong Fan, Ari Harju, Timon Rabczuk, Jean-Christophe Charlier
For centuries, cutting and folding papers with special patterns have been used to build beautiful, flexible and complex three-dimensional structures. Inspired by the old idea of kirigami (paper cutting), and the outstanding properties of graphene, recently graphene kirigami structures were fabricated to enhance the stretchability of graphene. However, the possibility of further tuning the electronic and thermal transport along the 2D kirigami structures has remained original to investigate. We therefore performed extensive atomistic simulations to explore the electronic, heat and load transfer along various graphene kirigami structures...
October 20, 2017: Nanoscale
Guido Grossi, Mette Dalgaard Ebbesen Jepsen, Jørgen Kjems, Ebbe Sloth Andersen
Biological systems use compartmentalisation as a general strategy to control enzymatic reactions by precisely regulating enzyme-substrate interactions. With the advent of DNA nanotechnology, it has become possible to rationally design DNA-based nano-containers with programmable structural and dynamic properties. These DNA nanostructures have been used to cage enzymes, but control over enzyme-substrate interactions using a dynamic DNA nanostructure has not been achieved yet. Here we introduce a DNA origami device that functions as a nanoscale vault: an enzyme is loaded in an isolated cavity and the access to free substrate molecules is controlled by a multi-lock mechanism...
October 19, 2017: Nature Communications
Wendy Kang, Alys R Clark, Merryn H Tawhai
Gravity and matched airway/vascular tree geometries are both hypothesized to be key contributors to ventilation-perfusion (V/Q) matching in the lung, but their relative contributions are challenging to quantify experimentally. We used a structure-based model to conduct an analysis of the relative contributions of tissue deformation (the 'Slinky' effect), other gravitational mechanisms (weight of blood and gravitational gradient in tissue elastic recoil), and matched airway and arterial tree geometry to V/Q matching and therefore to total lung oxygen exchange...
October 19, 2017: Journal of Applied Physiology
Michinari Hieda, Erin Howden, Shigeki Shibata, Takashi Tarumi, Justin Stevan Lawley, Christopher M Hearon, M Dean Palmer, Qi Fu, Rong Zhang, Satyam Sarma, Benjamin D Levine
The beat-to-beat dynamic Starling mechanism (DSM), the dynamic modulation of stroke volume (SV) due to breath-to-breath changes in left ventricular end-diastolic pressure (LVEDP), reflects ventricular-arterial coupling. The purpose of this study was to test whether LVEDP-SV relationship remained impaired in HFpEF patients after normalization of LVEDP. Right heart catheterization and model-flow analysis of the arterial pressure waveform were performed while preload was manipulated using lower body negative pressure to alter LVEDP...
October 19, 2017: Journal of Applied Physiology
Cetin Tas, Jessica C Joyce, Hiep X Nguyen, Padmanabhan Eangoor, Jennifer S Knaack, Ajay K Banga, Mark R Prausnitz
Migraine is a widespread neurological disease with negative effects on quality of life and productivity. Moderate to severe acute migraine attacks can be treated with dihydroergotamine mesylate (DHE), an ergot derivative that is especially effective in non-responders to triptan derivatives. To overcome limitations of current DHE formulations in subcutaneous injection and nasal spray such as pain, adverse side effects and poor bioavailability, a new approach is needed for DHE delivery enabling painless self-administration, quick onset of action, and high bioavailability...
October 16, 2017: Journal of Controlled Release: Official Journal of the Controlled Release Society
Kimberly A Buchanan, Roderic S Lakes, Ray Vanderby
Ex vivo tendon mechanical behavior has been well described under rotationally constrained uniaxial tensile testing. During standard loading of rat tail tendon (RTT) fascicles, apparent axial twist has been observed. To quantify this behavior, we designed a custom testing setup, utilizing magnetic suspension, to allow unconstrained axial rotation during tensile loading. We characterized the rotational behavior of single and paired RTT fascicles under cyclic loading. We also measured stress relaxation across loading cycles as well as "rotational relaxation"...
October 7, 2017: Journal of Biomechanics
Berit Carow, Yu Gao, Graciela Terán, Xuexian O Yang, Chen Dong, Akihiko Yoshimura, Martin E Rottenberg
CISH gene has been associated with increased susceptibility to human tuberculosis. We found that cish(-/-) mice had higher M. tuberculosis load in spleens and lungs up to 2.5 weeks after infection but not later compared to controls. Cish mRNA levels were increased in lungs at early and late time points after M. tuberculosis infection. In relation, the titers of inos and tnf mRNA in lungs were reduced early after infection of cish(-/-) mice. The transfer of cish(-/-) and control T cells conferred rag1(-/-) mice similar protection to infection with M...
December 2017: Tuberculosis
Jing Dai, Zahra Alaei, Beatrice Plazzotta, Jan Skov Pedersen, Istvan Furo
By combining NMR (yielding 1H chemical shift, spin relaxation and self-diffusion data) and SAXS experiments, we investigate the complex temperature dependence of the molecular and aggregate states in aqueous solutions of the surfactant [CH3(CH2)17(OCH2CH2)20OH], abbreviated C18E20, and hexamethyldisiloxane HMDSO. The latter molecule serves as a model for hydrophobic solubilizates. Previously, the pure micellar solution was demonstrated to exhibit core freezing at approx. 7-8 °C. At room temperature, we find that HMDSO solubilizes at a volume fraction of approx...
October 20, 2017: Journal of Physical Chemistry. B
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