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https://www.readbyqxmd.com/read/28069947/first-passage-time-approach-to-controlling-noise-in-the-timing-of-intracellular-events
#1
Khem Raj Ghusinga, John J Dennehy, Abhyudai Singh
In the noisy cellular environment, gene products are subject to inherent random fluctuations in copy numbers over time. How cells ensure precision in the timing of key intracellular events despite such stochasticity is an intriguing fundamental problem. We formulate event timing as a first-passage time problem, where an event is triggered when the level of a protein crosses a critical threshold for the first time. Analytical calculations are performed for the first-passage time distribution in stochastic models of gene expression...
January 9, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28069808/kinetic-modeling-and-analysis-of-the-akt-mechanistic-target-of-rapamycin-complex-1-mtorc1-signaling-axis-reveals-cooperative-feedforward-regulation
#2
Anisur Rahman, Jason M Haugh
Mechanistic target of rapamycin complex 1 (mTORC1) controls biosynthesis and has been implicated in uncontrolled cell growth in cancer. Although many details of mTORC1 regulation are well understood, a systems-level, predictive framework synthesizing those details is currently lacking. We constructed various mathematical models of mTORC1 activation mediated by Akt and aligned the model outputs to kinetic data acquired for growth factor-stimulated cells. A model based on a putative feedforward loop orchestrated by Akt consistently predicted how the pathway was altered by depletion of key regulatory proteins...
January 9, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28063499/analysis-of-phosphatidic-acid-binding-and-regulation-of-pipki-in-vitro-and-in-intact-cells
#3
L W R Tay, Z Wang, G Du
Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] is a lipid second messenger that regulates a wide array of essential cellular events, such as signal transduction, vesicle trafficking, actin cytoskeleton dynamics, adhesion, and motility. To control the spatiotemporal production of PI(4,5)P2, the activity of type 1 phosphotidylinositol-4-phosphate-5-kinases (PIPKIs) is tightly regulated by small GTPases and another signaling lipid, phosphatidic acid (PA). It is of interest that PI(4,5)P2 is also a critical cofactor for the activation of the PA-generating enzyme, phospholipase D (PLD)...
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28056364/estimation-of-biogas-and-methane-yields-in-an-uasb-treating-potato-starch-processing-wastewater-with-backpropagation-artificial-neural-network
#4
Philip Antwi, Jianzheng Li, Portia Opoku Boadi, Jia Meng, En Shi, Kaiwen Deng, Francis Kwesi Bondinuba
Three-layered feedforward backpropagation (BP) artificial neural networks (ANN) and multiple nonlinear regression (MnLR) models were developed to estimate biogas and methane yield in an upflow anaerobic sludge blanket (UASB) reactor treating potato starch processing wastewater (PSPW). Anaerobic process parameters were optimized to identify their importance on methanation. pH, total chemical oxygen demand, ammonium, alkalinity, total Kjeldahl nitrogen, total phosphorus, volatile fatty acids and hydraulic retention time selected based on principal component analysis were used as input variables, whiles biogas and methane yield were employed as target variables...
December 16, 2016: Bioresource Technology
https://www.readbyqxmd.com/read/28041912/a-constitutive-intrinsic-inflammatory-signaling-circuit-composed-of-mir-196b-meis2-ppp3cc-and-p65-drives-prostate-cancer-castration-resistance
#5
Ji-Hak Jeong, Sun-Jin Park, Shohreh Iravani Dickinson, Jun-Li Luo
Androgen deprivation therapy is the most effective treatment for advanced prostate cancer, but almost all cancer eventually becomes castration resistant, and the underlying mechanisms are largely unknown. Here, we show that an intrinsic constitutively activated feedforward signaling circuit composed of IκBα/NF-κB(p65), miR-196b-3p, Meis2, and PPP3CC is formed during the emergence of castration-resistant prostate cancer (CRPC). This circuit controls the expression of stem cell transcription factors that drives the high tumorigenicity of CRPC cells...
January 5, 2017: Molecular Cell
https://www.readbyqxmd.com/read/28026790/stabilization-of-neural-network-based-control-systems-via-event-triggered-control-with-nonperiodic-sampled-data
#6
Songlin Hu, Dong Yue, Xiangpeng Xie, Yong Ma, Xiuxia Yin
This paper focuses on a problem of event-triggered stabilization for a class of nonuniformly sampled neural-network-based control systems (NNBCSs). First, a new event-triggered data transmission mechanism is designed based on the nonperiodic sampled data. Different from the previous works, the proposed triggering scheme enables the NNBCSs design to enjoy the advantages of both nonuniform and event-triggered sampling schemes. Second, under the nonperiodic event-triggered data transmission scheme, the nonperiodic sampled-data three-layer fully connected feedforward neural-network (TLFCFFNN)-based event-triggered controller is constructed, and the resulting closed-loop TLFCFFNN-based event-triggered control system is modeled as a state delay system based on time-delay system modeling approach...
December 26, 2016: IEEE Transactions on Neural Networks and Learning Systems
https://www.readbyqxmd.com/read/27990245/feedback-error-learning-controller-for-functional-electrical-stimulation-assistance-in-a-hybrid-robotic-system-for-reaching-rehabilitation
#7
Francisco Resquín, Jose Gonzalez-Vargas, Jaime Ibáñez, Fernando Brunetti, José Luis Pons
Hybrid robotic systems represent a novel research field, where functional electrical stimulation (FES) is combined with a robotic device for rehabilitation of motor impairment. Under this approach, the design of robust FES controllers still remains an open challenge. In this work, we aimed at developing a learning FES controller to assist in the performance of reaching movements in a simple hybrid robotic system setting. We implemented a Feedback Error Learning (FEL) control strategy consisting of a feedback PID controller and a feedforward controller based on a neural network...
June 13, 2016: European Journal of Translational Myology
https://www.readbyqxmd.com/read/27990243/human-fes-cooperative-control-for-wrist-movement-a-preliminary-study
#8
Kai Gui, Hiroshi Yokoi, Dingguo Zhang
Functional electrical stimulation (FES) sometimes applies to patients with partial paralysis, so human voluntary control and FES control both exist. Our study aims to build a cooperative controller to achieve human-FES cooperation. This cooperative controller is formed by a classical FES controller and an impedance controller. The FES controller consists of a back propagation (BP) neural network-based feedforward controller and a PID-based feedback controller. The function of impedance controller is to convert volitional force/torque, which is estimated from a three-stage filter based on EMG, into additional angle...
June 13, 2016: European Journal of Translational Myology
https://www.readbyqxmd.com/read/27990236/electrotactile-feedback-improves-performance-and-facilitates-learning-in-the-routine-grasping-task
#9
Milica Isaković, Minja Belić, Matija Štrbac, Igor Popović, Strahinja Došen, Dario Farina, Thierry Keller
Aim of this study was to investigate the feasibility of electrotactile feedback in closed loop training of force control during the routine grasping task. The feedback was provided using an array electrode and a simple six-level spatial coding, and the experiment was conducted in three amputee subjects. The psychometric tests confirmed that the subjects could perceive and interpret the electrotactile feedback with a high success rate. The subjects performed the routine grasping task comprising 4 blocks of 60 grasping trials...
June 13, 2016: European Journal of Translational Myology
https://www.readbyqxmd.com/read/27980114/sodium-pumps-mediate-activity-dependent-changes-in-mammalian-motor-networks
#10
Laurence D Picton, Filipe Nascimento, Matthew J Broadhead, Keith T Sillar, Gareth B Miles
: Ubiquitously expressed sodium pumps are best known for maintaining the ionic gradients and resting membrane potential required for generating action potentials. However, activity- and state-dependent changes in pump activity can also influence neuronal firing and regulate rhythmic network output. Here we demonstrate that changes in sodium pump activity regulate locomotor networks in the spinal cord of neonatal mice. The sodium pump inhibitor, ouabain, increased the frequency and decreased the amplitude of drug-induced locomotor bursting, effects which were dependent on the presence of the neuromodulator dopamine...
December 15, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27973566/when-optimal-feedback-control-is-not-enough-feedforward-strategies-are-required-for-optimal-control-with-active-sensing
#11
Sang-Hoon Yeo, David W Franklin, Daniel M Wolpert
Movement planning is thought to be primarily determined by motor costs such as inaccuracy and effort. Solving for the optimal plan that minimizes these costs typically leads to specifying a time-varying feedback controller which both generates the movement and can optimally correct for errors that arise within a movement. However, the quality of the sensory feedback during a movement can depend substantially on the generated movement. We show that by incorporating such state-dependent sensory feedback, the optimal solution incorporates active sensing and is no longer a pure feedback process but includes a significant feedforward component...
December 2016: PLoS Computational Biology
https://www.readbyqxmd.com/read/27959333/a-single-high-dose-of-dexamethasone-affects-the-phosphorylation-state-of-glutamate-ampa-receptors-in-the-human-limbic-system
#12
M W Lopes, R B Leal, R Guarnieri, M L Schwarzbold, A Hoeller, A P Diaz, G L Boos, K Lin, M N Linhares, J C Nunes, J Quevedo, Z A Bortolotto, H J Markowitsch, S L Lightman, R Walz
Glucocorticoids (GC) released during stress response exert feedforward effects in the whole brain, but particularly in the limbic circuits that modulates cognition, emotion and behavior. GC are the most commonly prescribed anti-inflammatory and immunosuppressant medication worldwide and pharmacological GC treatment has been paralleled by the high incidence of acute and chronic neuropsychiatric side effects, which reinforces the brain sensitivity for GC. Synapses can be bi-directionally modifiable via potentiation (long-term potentiation, LTP) or depotentiation (long-term depression, LTD) of synaptic transmission efficacy, and the phosphorylation state of Ser831 and Ser845 sites, in the GluA1 subunit of the glutamate AMPA receptors, are a critical event for these synaptic neuroplasticity events...
December 13, 2016: Translational Psychiatry
https://www.readbyqxmd.com/read/27939218/a-multi-step-transcriptional-and-chromatin-state-cascade-underlies-motor-neuron-programming-from-embryonic-stem-cells
#13
Silvia Velasco, Mahmoud M Ibrahim, Akshay Kakumanu, Görkem Garipler, Begüm Aydin, Mohamed Ahmed Al-Sayegh, Antje Hirsekorn, Farah Abdul-Rahman, Rahul Satija, Uwe Ohler, Shaun Mahony, Esteban O Mazzoni
Direct cell programming via overexpression of transcription factors (TFs) aims to control cell fate with the degree of precision needed for clinical applications. However, the regulatory steps involved in successful terminal cell fate programming remain obscure. We have investigated the underlying mechanisms by looking at gene expression, chromatin states, and TF binding during the uniquely efficient Ngn2, Isl1, and Lhx3 motor neuron programming pathway. Our analysis reveals a highly dynamic process in which Ngn2 and the Isl1/Lhx3 pair initially engage distinct regulatory regions...
December 8, 2016: Cell Stem Cell
https://www.readbyqxmd.com/read/27929113/a-feedforward-inhibitory-circuit-mediated-by-cb1-expressing-fast-spiking-interneurons-in-the-nucleus-accumbens
#14
William J Wright, Oliver M Schlüter, Yan Dong
The nucleus accumbens (NAc) gates motivated behaviors through the functional output of principle medium spiny neurons (MSNs), whereas dysfunctional output of NAc MSNs contributes to a variety of psychiatric disorders. Fast-spiking interneurons (FSIs) are sparsely distributed throughout the NAc, forming local feedforward inhibitory circuits. It remains elusive how FSI-based feedforward circuits regulate the output of NAc MSNs. Here, we investigated a distinct subpopulation of NAc FSIs that express the cannabinoid receptor type-1 (CB1)...
January 4, 2017: Neuropsychopharmacology: Official Publication of the American College of Neuropsychopharmacology
https://www.readbyqxmd.com/read/27924313/a-compartmentalized-out-of-equilibrium-enzymatic-reaction-network-for-sustained-autonomous-movement
#15
Marlies Nijemeisland, Loai K E A Abdelmohsen, Wilhelm T S Huck, Daniela A Wilson, Jan C M van Hest
Every living cell is a compartmentalized out-of-equilibrium system exquisitely able to convert chemical energy into function. In order to maintain homeostasis, the flux of metabolites is tightly controlled by regulatory enzymatic networks. A crucial prerequisite for the development of lifelike materials is the construction of synthetic systems with compartmentalized reaction networks that maintain out-of-equilibrium function. Here, we aim for autonomous movement as an example of the conversion of feedstock molecules into function...
November 23, 2016: ACS Central Science
https://www.readbyqxmd.com/read/27917149/wavelet-packet-feature-assessment-for-high-density-myoelectric-pattern-recognition-and-channel-selection-toward-stroke-rehabilitation
#16
Dongqing Wang, Xu Zhang, Xiaoping Gao, Xiang Chen, Ping Zhou
This study presents wavelet packet feature assessment of neural control information in paretic upper limb muscles of stroke survivors for myoelectric pattern recognition, taking advantage of high-resolution time-frequency representations of surface electromyogram (EMG) signals. On this basis, a novel channel selection method was developed by combining the Fisher's class separability index and the sequential feedforward selection analyses, in order to determine a small number of appropriate EMG channels from original high-density EMG electrode array...
2016: Frontiers in Neurology
https://www.readbyqxmd.com/read/27913590/control-of-spike-transfer-at-hippocampal-mossy-fiber-synapses-in-vivo-by-gabaa-and-gabab-receptor-mediated-inhibition
#17
Stefano Zucca, Marilena Griguoli, Meryl Malézieux, Noëlle Grosjean, Mario Carta, Christophe Mulle
: Despite extensive studies in hippocampal slices and incentive from computational theories, the synaptic mechanisms underlying information transfer at mossy fiber (mf) connections between the dentate gyrus (DG) and CA3 neurons in vivo are still elusive. Here we used an optogenetic approach in mice to selectively target and control the activity of DG granule cells (GCs) while performing whole cell and juxtacellular recordings of CA3 neurons in vivo In CA3 pyramidal cells (PCs), mf-CA3 synaptic responses consisted predominantly of an inhibitory postsynaptic potential (IPSP) at low stimulation frequency (0...
December 2, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27911754/cortical-control-of-spatial-resolution-by-vip-interneurons
#18
Inbal Ayzenshtat, Mahesh Miikael Karnani, Jesse Jackson, Rafael Yuste
: Neuronal tuning, defined by the degree of selectivity to a specific stimulus, is a hallmark of cortical computation. Understanding the role of GABAergic interneurons in shaping cortical tuning is now possible with the ability to manipulate interneuron classes selectively. Here, we show that interneurons expressing vasoactive intestinal polypeptide (VIP(+)) regulate the spatial frequency (SF) tuning of pyramidal neurons in mouse visual cortex. Using two-photon calcium imaging and optogenetic manipulations of VIP(+) cell activity, we found that activating VIP(+) cells elicited a stronger network response to stimuli of higher SFs, whereas suppressing VIP(+) cells resulted in a network response shift toward lower SFs...
November 9, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27894998/push-pull-and-feedback-mechanisms-can-align-signaling-system-outputs-with-inputs
#19
Steven S Andrews, William J Peria, Richard C Yu, Alejandro Colman-Lerner, Roger Brent
Many cell signaling systems, including the yeast pheromone response system, exhibit "dose-response alignment" (DoRA), in which output of one or more downstream steps closely matches the fraction of occupied receptors. DoRA can improve the fidelity of transmitted dose information. Here, we searched systematically for biochemical network topologies that produced DoRA. Most networks, including many containing feedback and feedforward loops, could not produce DoRA. However, networks including "push-pull" mechanisms, in which the active form of a signaling species stimulates downstream activity and the nominally inactive form reduces downstream activity, enabled perfect DoRA...
November 23, 2016: Cell Systems
https://www.readbyqxmd.com/read/27881971/familial-longevity-is-not-associated-with-major-differences-in-the-hypothalamic-pituitary-gonadal-axis-in-healthy-middle-aged-men
#20
Evie van der Spoel, Ferdinand Roelfsema, Steffy W Jansen, Abimbola A Akintola, Bart E Ballieux, Christa M Cobbaert, Gerard J Blauw, P Eline Slagboom, Rudi G J Westendorp, Hanno Pijl, Diana van Heemst
CONTEXT: A trade-off between fertility and longevity possibly exists. The association of the male hypothalamic-pituitary-gonadal (HPG) axis with familial longevity has not yet been investigated. OBJECTIVE: To study 24-h hormone concentration profiles of the HPG axis in men enriched for familial longevity and controls. DESIGN: We frequently sampled blood over 24 h in 10 healthy middle-aged male offspring of nonagenarian participants from the Leiden Longevity Study together with 10 male age-matched controls...
2016: Frontiers in Endocrinology
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