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Mechanical force

Neha Maurya, Mehraj Ud Din Parray, Jitendra Kumar Maurya, Amit Kumar, Rajan Patel
The binding nature of amphiphilic drugs viz. promethazine hydrochloride (PMT) and adiphenine hydrochloride (ADP), with human hemoglobin (Hb) was unraveled by fluorescence, absorbance, time resolved fluorescence, fluorescence resonance energy transfer (FRET) and circular dichroism (CD) spectral techniques in combination with molecular docking and molecular dynamic simulation methods. The steady state fluorescence spectra indicated that both PMT and ADP quenches the fluorescence of Hb through static quenching mechanism which was further confirmed by time resolved fluorescence spectra...
March 11, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Manabu Masuda, Takashi Iida, Fernando G Exposto, Lene Baad-Hansen, Misao Kawara, Osamu Komiyama, Peter Svensson
AIMS: To determine if standardized palpation of the masseter muscle can evoke referred pain and/or sensations in healthy individuals and to compare the mechanical sensitivities in response to three different levels of palpation force. METHODS: A total of 32 pain-free individuals participated. The right masseter muscle was divided into 15 test sites. Mechanical sensitivity of the masseter was assessed with three mechanical stimuli (0.5 kg, 1.0 kg, or 2.0 kg) applied by palpometers to the 15 test sites for 5 seconds each site...
March 21, 2018: Journal of Oral & Facial Pain and Headache
Hannah Brooks, Grant E Haines, M Carly Lin, S Laurie Sanderson
Vortical cross-step filtration in suspension-feeding fish has been reported recently as a novel mechanism, distinct from other biological and industrial filtration processes. Although crossflow passing over backward-facing steps generates vortices that can suspend, concentrate, and transport particles, the morphological factors affecting this vortical flow have not been identified previously. In our 3D-printed models of the oral cavity for ram suspension-feeding fish, the angle of the backward-facing step with respect to the model's dorsal midline affected vortex parameters significantly, including rotational, tangential, and axial speed...
2018: PloS One
Chrysovalantis Voutouri, Triantafyllos Stylianopoulos
Hyaluronan is abundant in the extracellular matrix of many desmoplastic tumors and determines in large part the tumor biochemical and mechanical microenvironment. Additionally, it has been identified as one of the major physiological barriers to the effective delivery of drugs to solid tumors and its targeting with the use of pharmaceutical agents has shown to decompress tumor blood vessels, and thus improve tumor perfusion and efficacy of cytotoxic drugs. In this study, we investigated the contribution of hyaluronan to the accumulation of mechanical forces in tumors...
2018: PloS One
Nobukazu Shirakawa, Toshio Iwata, Shinjiro Miyake, Takero Otuka, So Koizumi, Toshitugu Kawata
OBJECTIVES: To evaluate the esthetics and frictional force of an orthodontic wire passed through a newly designed tube made of a polyether ether ketone (PEEK) resin. MATERIALS AND METHODS: Two types of standard PEEK tubes were prepared at 0.5 × 0.6ф and 0.8 × 0.9ф, and different archwires were passed through the tubes. Color values were determined according to brightness and hues. Friction was assessed with different bracket-wire combinations, and surface roughness was determined by stereomicroscopy before and after the application of friction...
March 21, 2018: Angle Orthodontist
Markus Selmke, Utsab Khadka, Andreas P Bregulla, Frank Cichos, Haw Yang
Photon nudging is a new experimental method which enables the force-free manipulation and localization of individual self-propelled artificial micro-swimmers in fluidic environments. It uses a weak laser to stochastically and adaptively turn on and off the swimmer's propulsion when the swimmer, through rotational diffusion, points towards or away from its target, respectively. This contribution presents a theoretical framework for the statistics of both 2D and 3D controls. The main results are: the on- and off-time distributions for the controlling laser, the arrival time statistics for the swimmer to reach a remote target, and how the experimentally accessible control parameters influence the control, e...
March 21, 2018: Physical Chemistry Chemical Physics: PCCP
Benjamin L Ricca, Gautham Venugopalan, Saori Furuta, Kandice Tanner, Walter A Orellana, Clay D Reber, Douglas G Brownfield, Mina J Bissell, Daniel A Fletcher
Non-malignant breast epithelial cells cultured in three-dimensional laminin-rich extracellular matrix (lrECM) form well organized, growth-arrested acini, whereas malignant cells form continuously growing disorganized structures. While the mechanical properties of the microenvironment have been shown to contribute to formation of tissue-specific architecture, how transient external force influences this behavior remains largely unexplored. Here, we show that brief transient compression applied to single malignant breast cells in lrECM stimulated them to form acinar-like structures, a phenomenon we term 'mechanical reversion...
March 21, 2018: ELife
Alexander Heiss, Daesung Park, Anna-Christin Joel
Spiders are natural specialists in fiber processing. In particular, cribellate spiders manifest this ability as they produce a wool of nanofibers to capture prey. During its production they deploy a sophisticated movement of their spinnerets to darn in the fibers as well as a comb-like row of setae, termed calamistrum, on the metatarsus which plays a key role in nanofiber processing. In comparison to the elaborate nanofiber extraction and handling process by the spider's calamistrum, the human endeavors of spinning and handling of artificial nanofibers is still a primitive technical process...
March 21, 2018: Microscopy and Microanalysis
N Laube, F Bernsmann, C Fisang
Urological implants in the urinary tract are routinely used to ensure urine flow. However, the morbidities are numerous concerning long-term derivations. Especially with the ureteral stents, failure can have considerable consequences. Since the surfaces of all urological implants are more or less ideal substrates for microorganisms, the formation of bacterial biofilms is a regularly observed and often serious complication, which in many cases forces early implant replacement. The burden on the patient and the health system are enormous...
March 20, 2018: Der Urologe. Ausg. A
Sven van Teeffelen, Lars D Renner
Cell shape and cell volume are important for many bacterial functions. In recent years, we have seen a range of experimental and theoretical work that led to a better understanding of the determinants of cell shape and size. The roles of different molecular machineries for cell-wall expansion have been detailed and partially redefined, mechanical forces have been shown to influence cell shape, and new connections between metabolism and cell shape have been proposed. Yet the fundamental determinants of the different cellular dimensions remain to be identified...
2018: F1000Research
Marco Janko, Michael Wiertlewski, Yon Visell
When we touch an object, complex frictional forces are produced, aiding us in perceiving surface features that help to identify the object at hand, and also facilitating grasping and manipulation. However, even during controlled tactile exploration, sliding friction forces fluctuate greatly, and it is unclear how they relate to the surface topography or mechanics of contact with the finger. We investigated the sliding contact between the finger and different relief surfaces, using high-speed video and force measurements...
March 20, 2018: Scientific Reports
Érica Lofrano Reghine, Caio César Inaco Cirino, André Amate Neto, Fabiana Rossi Varallo, Paulo Roberto Barbosa Évora, Tales Rubens de Nadai
BACKGROUND Kirschner wires are often used to perform osteosynthesis. Migration through tissue of these wires is a rare but well-known occurrence. CASE REPORT A 65-year-old female presented with light intensity pain complaints in the upper left chest area; personal history included left clavicle fracture 20 years ago that was treated surgically with fixation using a K-wire. Chest radiography showed the presence of metallic foreign body in the left pulmonary apex. An exploratory axillary thoracotomy was performed, and the foreign body was extracted by a pneumotomy...
March 21, 2018: American Journal of Case Reports
George A Sutherland, Katie J Grayson, Nathan B P Adams, Daphne M J Mermans, Alexander S Jones, Angus J Robertson, Dirk B Auman, Amanda A Brindley, Fabio Sterpone, Pierre Tuffery, Philippe Derreumaux, P Leslie Dutton, Colin Robinson, Andrew Hitchcock, C Neil Hunter
Protein transport across the cytoplasmic membrane of bacterial cells is mediated by either the general secretion (Sec) system or the twin arginine translocase (Tat). The Tat machinery exports folded and cofactor containing proteins from the cytoplasm to the periplasm by using the transmembrane proton motive force as a source of energy. The Tat apparatus apparently senses the folded state of its protein substrates, a quality control mechanism that prevents premature export of nascent unfolded or misfolded polypeptides, but its mechanistic basis has not yet been determined...
March 20, 2018: Journal of Biological Chemistry
Masanori Kawakami, Lisa Maria Mustachio, Xi Liu, Ethan Dmitrovsky
Cancer cells often have supernumerary centrosomes that promote genomic instability, a pathognomonic feature of cancer. During mitosis, cancer cells with supernumerary centrosomes undergo bipolar cell division by clustering centrosomes into two poles. When supernumerary centrosome clustering is antagonized, cancer cells are forced to undergo multipolar division leading to death of daughter cells. This proapoptotic pathway, called anaphase catastrophe, preferentially eliminates aneuploid cancer cells and malignant tumors in engineered mouse models...
March 20, 2018: Molecular Cancer Therapeutics
Karem H Alzoubi, Omar F Khabour, Mohammad Ahmad
Posttraumatic stress disorder (PTSD) is a disabling prevalent and difficult-to-treat psychiatric disorder, which can develop after the exposure to severe traumatic events such as those occurring during wars and natural disasters. Pentoxifylline (PTX) is a potent antioxidant, which has an important role in prevention of cognitive dysfunctions. In the present study, the effect of PTX on memory impairment induced by PTSD was investigated using the rat animal model. PTSD-like behavior was induced in animals using a single-prolonged stress (SPS) rat model of PTSD (2 h restrain, 20 min forced swimming, 15 min rest, 1-2 min diethyl ether exposure)...
March 17, 2018: Brain Research Bulletin
Yaowen Xing, Mengdi Xu, Xiahui Gui, Yijun Cao, Bent Babel, Martin Rudolph, Stefan Weber, Michael Kappl, Hans-Jürgen Butt
During the past years, atomic force microscopy (AFM) has matured to an indispensable tool to characterize nanomaterials in colloid and interface science. For imaging, a sharp probe mounted near to the end of a cantilever scans over the sample surface providing a high resolution three-dimensional topographic image. In addition, the AFM tip can be used as a force sensor to detect local properties like adhesion, stiffness, charge etc. After the invention of the colloidal probe technique it has also become a major method to measure surface forces...
February 6, 2018: Advances in Colloid and Interface Science
Frances T Sheehan, Elizabeth L Brainerd, Karen L Troy, Sandra J Shefelbine, Janet L Ronsky
Although all functional movement arises from the interplay between the neurological, skeletal, and muscular systems, it is the skeletal system that forms the basic framework for functional movement. Central to understanding human neuromuscular development, along with the genesis of musculoskeletal pathologies, is quantifying how the human skeletal system adapts and mal-adapts to its mechanical environment. Advancing this understanding is hampered by an inability to directly and non-invasively measure in vivo strains, stresses, and forces on bone...
March 20, 2018: Journal of Neuroengineering and Rehabilitation
Steven F Shannon, Chelsea C Boe, Alexander Y Shin
Axial carpal injuries are rare entities where a traumatic force transmits through the intermetacarpal space, dissociating the carpometacarpal joint and disrupting the distal carpal row in an axial radial or axial ulnar pattern via true axial force or compressive crush mechanism. Differences in outcomes remain unclear with regard to the specific type of axial carpal injury pattern. A retrospective case series identified 37 wrists (in 37 patients) over 25 years who presented to a Level 1 trauma centre, with 20 wrists experiencing an axial radial injury and 17 wrists experiencing an axial ulnar injury...
January 1, 2018: Journal of Hand Surgery, European Volume
Javier I Borráz-León, Ana Lilia Cerda-Molina, Markus J Rantala, Lilian Mayagoitia-Novales
Higher testosterone levels have been positively related to a variety of social behaviors and personality traits associated with intrasexual competition. The aim of this study was to evaluate the role of testosterone levels and personality traits such as aggressiveness, competitiveness, and self-esteem on the task of choosing a fighting competitor (a rival) with or without a motivation to fight. In Study 1, a group of 119 men participated in a task for choosing a rival through pictures of men with high-dominant masculinity versus low-dominant masculinity...
January 2018: Evolutionary Psychology: An International Journal of Evolutionary Approaches to Psychology and Behavior
Shahid Khan, Jonathan M Scholey
Cells from all three domains of life on Earth utilize motile macromolecular devices that protrude from the cell surface to generate forces that allow them to swim through fluid media. Research carried out on archaea during the past decade or so has led to the recognition that, despite their common function, the motility devices of the three domains display fundamental differences in their properties and ancestry, reflecting a striking example of convergent evolution. Thus, the flagella of bacteria and the archaella of archaea employ rotary filaments that assemble from distinct subunits that do not share a common ancestor and generate torque using energy derived from distinct fuel sources, namely chemiosmotic ion gradients and FlaI motor-catalyzed ATP hydrolysis, respectively...
March 19, 2018: Current Biology: CB
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