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Biological motion

R D Astumian
Molecular machines use external energy to drive transport, to do mechanical, osmotic, or electrical work on the environment, and to form structure. In this paper the fundamental difference between the design principles necessary for a molecular machine to use light or external modulation of thermodynamic parameters as an energy source vs. the design principle for using an exergonic chemical reaction as a fuel will be explored. The key difference is that for catalytically-driven motors microscopic reversibility must hold arbitrarily far from equilibrium...
October 21, 2016: Faraday Discussions
Jamie M Schiffer, Victoria A Feher, Robert D Malmstrom, Roxana Sida, Rommie E Amaro
Proteins commonly sample a number of conformational states to carry out their biological function, often requiring transitions from the ground state to higher-energy states. Characterizing the mechanisms that guide these transitions at the atomic level promises to impact our understanding of functional protein dynamics and energy landscapes. The leucine-99-to-alanine (L99A) mutant of T4 lysozyme is a model system that has an experimentally well characterized excited sparsely populated state as well as a ground state...
October 18, 2016: Biophysical Journal
D Caballero, J Katuri, J Samitier, S Sánchez
The ubiquitous random motion of mesoscopic active particles, such as cells, can be "rectified" or directed by embedding the particles in systems containing local and periodic asymmetric cues. Incorporated on lab-on-a-chip devices, these microratchet-like structures can be used to self-propel fluids, transport particles, and direct cell motion in the absence of external power sources. In this Focus article we discuss recent advances in the use of ratchet-like geometries in microfluidics which could open new avenues in biomedicine for applications in diagnosis, cancer biology, and bioengineering...
October 19, 2016: Lab on a Chip
Sa Liu, Yulong Chen, Shiping Xie, Qianlei Xu, Jianshe Chen, Changhai Wang, Zhao Wang, Suna Ma, Xingwei Wu, Ning Zhang
OBJECTIVES: Traditional Chinese Medicine (TCM) applied in the clinic as a complementary and alternative therapy has helped improve immunity and reduce side effects and symptomatic treatment in patients with HIV/AIDS. However, the mechanisms of TCM syndromes are not clear. Transcriptomics enables the study of such TCM syndromes. DESIGN: This study compared the messenger RNA (mRNA) expressions of healthy persons and patients with HIV/AIDS who had two common TCM syndromes, qi-yin deficiency and dampness-heat retention, to find the difference in HIV/AIDS with TCM syndromes...
October 19, 2016: Journal of Alternative and Complementary Medicine: Research on Paradigm, Practice, and Policy
Dahan Anat, Reiner Miriam
The extensive use of gestures for human-human communication, independently of culture and language, suggests an underlying universal neural mechanism for gesture recognition. The mirror neuron system (MNS) is known to respond to observed human actions, and overlaps with self-action. The minimal cues needed for activation of the MNS for gesture recognition, facial expressions and bodily dynamics, is not yet defined. Using LED-point representations of gestures, we compared two types of brain activations: 1) in response to human recognizable vs non-recognizable motion and 2) in response to human vs non-human motion...
October 15, 2016: International Journal of Psychophysiology
Yu Ding, Di-Ke Ruan, Qing He, Li Sheng Hou, Jian Ning Lin, Hong Peng Cui
STUDY DESIGN: The clinical and radiologic data of total disk allografting (TDA) cases were collected and analyzed to explore the correlation between neurological function improvements and imaging changes. OBJECTIVE: The aim of the study was to assess the medium-term and long-term outcome and radiographic character after TDA, and, furthermore, to explore the significance of the changes of imaging signs after the transplantation. SUMMARY OF BACKGROUND DATA: Spinal fusion may result in the adjacent segment degeneration...
November 2016: Clinical Spine Surgery
Martina F Callaghan, Siawoosh Mohammadi, Nikolaus Weiskopf
Quantitative MRI (qMRI) provides standardized measures of specific physical parameters that are sensitive to the underlying tissue microstructure and are a first step towards achieving maps of biologically relevant metrics through in vivo histology using MRI. Recently proposed models have described the interdependence of qMRI parameters. Combining such models with the concept of image synthesis points towards a novel approach to synthetic qMRI, in which maps of fundamentally different physical properties are constructed through the use of biophysical models...
October 18, 2016: NMR in Biomedicine
Antoine Wystrach, Konstantinos Lagogiannis, Barbara Webb
Taxis behaviour in Drosophila larva is thought to consist of distinct control mechanisms triggering specific actions. Here we support a simpler hypothesis: that taxis results from direct sensory modulation of continuous lateral oscillations of the anterior body, sparing the need for 'action selection'. Our analysis of larvae motion reveals a rhythmic, continuous lateral oscillation of the anterior body, encompassing all head-sweeps, small or large, without breaking the oscillatory rhythm. Further, we show that an agent-model that embeds this hypothesis reproduces a surprising number of taxis signatures observed in larvae...
October 18, 2016: ELife
Guohua Tao
Accurately describing nuclear motion is crucial in electronically nonadiabatic dynamics simulations. In this work, a coherence-controlled (CC) approach is proposed based on the mapping between the classical state space and the full electronic matrix and that between the decomposed state space and different nuclear dynamics that allows nuclear motion to properly follow either Ehrenfest dynamics in the coherence domain or Born-Oppenheimer-like dynamics in the single-state domain in a consistent manner. This new method is applied to several benchmark models involving nonadiabatic transitions in two-state or three-state systems, and the obtained results are in excellent agreement with exact quantum calculations...
October 17, 2016: Journal of Physical Chemistry Letters
Carmine Di Rienzo, Paolo Annibale
The determination of the mode and rapidity of motion of individual molecules within a biological sample is becoming a more and more common analysis in biophysical investigations. Single molecule tracking (SMT) techniques allow reconstructing the trajectories of individual molecules within a movie, provided that the position from one frame to the other can be correctly linked. The outcomes, however, appear to depend on the specific method used, and most techniques display a limitation to capture fast modes of motion in a crowded environment...
October 1, 2016: Optics Letters
Muhammad A J Qadri, Robert G Cook
The biological mechanisms used to categorize and recognize behaviors are poorly understood in both human and non-human animals. Using animated digital models, we have recently shown that pigeons can categorize different locomotive animal gaits and types of complex human behaviors. In the current experiments, pigeons (go/no-go task) and humans (choice task) both learned to conditionally categorize two categories of human behaviors that did not repeat and were comprised of the coordinated motions of multiple limbs...
October 13, 2016: Vision Research
Nikolai Blanik, Konrad Heimann, Carina Pereira, Michael Paul, Vladimir Blazek, Boudewijn Venema, Thorsten Orlikowsky, Steffen Leonhardt
Vital parameter monitoring of term and preterm infants during incubator care with self-adhesive electrodes or sensors directly positioned on the skin [e.g. photoplethysmography (PPG) for oxygen saturation or electrocardiography (ECG)] is an essential part of daily routine care in neonatal intensive care units. For various reasons, this kind of monitoring contains a lot of stress for the infants. Therefore, there is a need to measure vital parameters (for instance respiration, temperature, pulse, oxygen saturation) without mechanical or conductive contact...
October 15, 2016: Biomedizinische Technik. Biomedical Engineering
Jason Hindes, Klementyna Szwaykowska, Ira B Schwartz
Swarming behavior continues to be a subject of immense interest because of its centrality in many naturally occurring systems in physics and biology, as well as its importance in applications such as robotics. Here we examine the effects on swarm pattern formation from delayed communication and topological heterogeneity, and in particular, the inclusion of a relatively small number of highly connected nodes, or "motherships," in a swarm's communication network. We find generalized forms of basic patterns for networks with general degree distributions, and a variety of dynamic behaviors including parameter regions with multistability and hybrid motions in bimodal networks...
September 2016: Physical Review. E
Stefania Brocca, Cristian Ferrari, Alberto Barbiroli, Alessandra Pesce, Marina Lotti, Marco Nardini
Life in cold environments requires an overall increase in the flexibility of macromolecular and supramolecular structures to allow biological processes to take place at low temperature. Conformational flexibility supports high catalytic rates of enzymes in the cold but in several cases is also a cause of instability. The three-dimensional structure of the psychrophilic acyl aminoacyl peptidase from Sporosarcina psychrophila (SpAAP) reported in this paper highlights adaptive molecular changes resulting in a fine-tuned trade-off between flexibility and stability...
October 14, 2016: FEBS Journal
Gayan Senavirathne, Santosh K Mahto, Jeungphill Hanne, Daniel O'Brian, Richard Fishel
Wrapping of genomic DNA into nucleosomes poses thermodynamic and kinetic barriers to biological processes such as replication, transcription, repair and recombination. Previous biochemical studies have demonstrated that in the presence of adenosine triphosphate (ATP) the human RAD51 (HsRAD51) recombinase can form a nucleoprotein filament (NPF) on double-stranded DNA (dsDNA) that is capable of unwrapping the nucleosomal DNA from the histone octamer (HO). Here, we have used single molecule Förster Resonance Energy Transfer (smFRET) to examine the real time nucleosome dynamics in the presence of the HsRAD51 NPF...
October 13, 2016: Nucleic Acids Research
M J Paldino, F Golriz, M L Chapieski, W Zhang, Z D Chu
BACKGROUND AND PURPOSE: The biologic basis for intelligence rests to a large degree on the capacity for efficient integration of information across the cerebral network. We aimed to measure the relationship between network architecture and intelligence in the pediatric, epileptic brain. MATERIALS AND METHODS: Patients were retrospectively identified with the following: 1) focal epilepsy; 2) brain MR imaging at 3T, including resting-state functional MR imaging; and 3) full-scale intelligence quotient measured by a pediatric neuropsychologist...
October 13, 2016: AJNR. American Journal of Neuroradiology
You-Gui Huang, Yoshihito Shiota, Sheng-Qun Su, Shu-Qi Wu, Zi-Shuo Yao, Guo-Ling Li, Shinji Kanegawa, Soonchul Kang, Takashi Kamachi, Kazunari Yoshizawa, Katsuhiko Ariga, Osamu Sato
Proton transport via dynamic molecules is ubiquitous in chemistry and biology. However, its use as a switching mechanism for properties in functional molecular assemblies is far less common. In this study, we demonstrate how an intra-carboxyl proton shuttle can be generated in a molecular assembly akin to a rack-and-pinion cascade via a thermally induced single-crystal-to-single-crystal phase transition. In a triply interpenetrated supramolecular organic framework (SOF), a 4,4'-azopyridine (azpy) molecule connects to two biphenyl-3,3',5,5'-tetracarboxylic acid (H4 BPTC) molecules to form a functional molecular system with switchable mechanical properties...
October 13, 2016: Angewandte Chemie
Lin Ren, Weibing She, Qingyu Gao, Changwei Pan, Chen Ji, Irving R Epstein
Crawling motion mediated by retrograde and direct waves, that is, in the opposite or the same direction, respectively, as the muscular wave that generates it, is a fundamental mode of biological locomotion, from which more complex and sophisticated locomotion modes involving outgrowths such as limbs and wings may have evolved. A detailed general description of muscular wave locomotion and its relationship with other modes of locomotion is a challenging task. We employ a model of a photosensitive self-oscillating gel, in which chemical pulse waves and a stimulus-responsive medium play roles analogous to nerve pulses and deformable muscles in an animal, to generate retrograde and direct waves under non-uniform illumination...
October 13, 2016: Angewandte Chemie
Alexander V Soudackov, Sharon Hammes-Schiffer
A general theory has been developed for proton-coupled electron transfer (PCET), which is vital to a wide range of chemical and biological processes. This theory describes PCET reactions in terms of nonadiabatic transitions between reactant and product electron-proton vibronic states and includes the effects of thermal fluctuations of the solvent or protein environment, as well as the proton donor-acceptor motion. Within the framework of this general PCET theory, a series of analytical rate constant expressions has been derived for PCET reactions in well-defined regimes...
October 13, 2016: Faraday Discussions
Daniel Van Opdenbosch, Gerhard Fritz-Popovski, Johann Plank, Cordt Zollfrank, Oskar Paris
Living nature and human technology apply different principles to create hard, strong and tough materials. In this review, we compare and discuss prominent aspects of these alternative strategies, and demonstrate for selected examples that nanoscale-precision biotemplating is able to produce uncommon mechanical properties as well as actuating behavior, resembling to some extent the properties of the original natural templates. We present and discuss mechanical testing data showing for the first time that nanometer-precision biotemplating can lead to porous ceramic materials with deformation characteristics commonly associated with either biological or highly advanced technical materials...
October 13, 2016: Bioinspiration & Biomimetics
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