21 research outputs found
Potential of synergist ablation to study mechanisms of skeletal muscle hypertrophy in rodent disease models
No full text: Synergist ablation (SA) is a well-established model of mechanical overload-induced hypertrophy in rodents, commonly used to infer skeletal muscle adaptation to resistance training in humans. Given the critical role of skeletal muscle atrophy in chronic conditions such as neuromuscular, metabolic, and cardiopulmonary disorders, SA represents a promising preclinical tool to study muscle hypertrophy mechanisms in pathological states. However, while extensively characterized in healthy animals, the potential applications of SA in disease models remain largely overlooked. This Mini-Review summarizes existing studies employing SA in rodent disease models, highlighting the diverse hypertrophic responses observed across conditions, including Duchenne muscular dystrophy, obesity, diabetes, cancer cachexia, and chronic kidney disease. Although hypertrophy gains are generally attenuated in diseased animals compared to healthy controls, SA-induced overload provides valuable insights into disease-specific regulatory mechanisms, including alterations in intracellular signaling, fiber-type transitions, and disease phenotype. We also discuss the strengths and limitations of SA as a preclinical model for resistance training in disease contexts and propose its broader adoption for mechanistic investigations into skeletal muscle plasticity under pathological conditions
The JKR formalism in applications to problems of adhesive contact
No full textThe JKR (Johnson-Kendall-Roberts) problem of adhesive contact between elastic spheres is an example of a mathematically beautiful theory that has many practical applications. However, it would be erroneous to reduce the JKR theory to just the problem of adhesive contact between spheres. Indeed, simultaneously with the presentation of the JKR theory, Kendall (J Phys D Appl Phys 4:1186–1195, 1971) applied the equilibrium theory of adhesion to bodies of other geometries and coatings. It gives a review of applications of the JKR formalism to axisymmetric indenters of various shapes, various elastic materials, different conditions of contact, and elastic structures. These structures include thin and thick elastic layers and atomically thin stretched membranes. The JKR formalism means that an adhesive contact problem may be solved by combining two ideas: (1) the Derjaguin balance energy approach (Derjaguin, Kolloid Z 69:155–164, 1934) and (2) superposition of solutions to two non-adhesive contact problems (the Hertz-type and the Boussinesq-type problems). The JKR formalism may be used if the distance between the free surface of the material and the indenter surface increases rapidly at the periphery of the contact region and the solutions of two contact problems having the same contact area may be superimposed on each other. It is shown that the JKR formalism may be reinforced if one employs the properties of slopes of the force-displacement diagrams of non-adhesive indentation. For the first time, such reinforcements were demonstrated explicitly by the author (Borodich, Adv Appl Mech 47:225–366, 2014). It is argued that the JKR formalism may be applied to an enormous number of adhesive contact problems for various elastic structures
Intertekstualiteit en die Bose in <i>Kroniek van Perdepoort</i> (Anna M. Louw)
No full textIn Anna M. Louw’s novel Kroniek van Perdepoort the primal conflict between good and evil is an important constituent element. Well-known authors in world literature have been fascinated by this problem, and it is an enriching experience to bring together allusions and to investigate points of contact with authors such as Feodor Dostoyevsky, Thomas Mann. William Faulkner and Patrick White. In Kroniek van Perdepoort there is a meeting between Klaas Kamer and the devil. Similarities between this meeting and similar meetings in Dr Faustus (Thomas Mann) and The Brothers Karamazov (Dostoyevsky) are pointed out.
Subsequently the portrayal of sin in Kroniek van Perdepoort is compared with Faulkner’s novels The Sound and the Fury and Absalom, Absalom!, in which a similar theme is represented.
Patrick White is also an author of religious literature to whom Anna M. Louw is attracted by her own admission. His novels. The solid Mandala and Riders in the Chariot are studied, and similarities with Kroniek van Perdepoort indicated
Vortex qubit based on an annular Josephson junction containing a microshort
No full textWe report theoretical and experimental work on the development of a vortex qubit based on a microshort in
an annular Josephson junction. The microshort creates a potential barrier for the vortex, which produces a
double-well potential under the application of an in-plane magnetic field; the field strength tunes the barrier
height. A one-dimensional model for this system is presented, from which we calculate the vortex-depinning
current and attempt frequency as well as the interwell coupling. Implementation of an effective microshort is
achieved via a section of insulating barrier that is locally wider in the junction plane. Using a junction with this
geometry we demonstrate classical state preparation and readout. The vortex is prepared in a given potential
well by sending a series of “shaker” bias-current pulses through the junction. Readout is accomplished by
measuring the vortex-depinning current
Reactivity studies on [Cp ` Fe(mu-I)](2): nitrido-, sulfido- and diselenide iron complexes derived from pseudohalide activation
No full textbibtex: ISI:000400553000098 bibtex\location:'THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND',publisher:'ROYAL SOC CHEMISTRY',type:'Article',affiliation:'Walter, MD (Reprint Author), Tech Univ Carolo Wilhelmina Braunschweig, Inst Anorgan & Analyt Chem, Hagenring 30, D-38106 Braunschweig, Germany. Maron, L (Reprint Author), Univ Toulouse, INSA UPS LPCNO, CNRS LPCNO, 135 Ave Rangueil, F-31077 Toulouse, France. Reiners, Matthias; Maekawa, Miyuki; Daniliuc, Constantin G.; Freytag, Matthias; Jones, Peter G.; Walter, Marc D., Tech Univ Carolo Wilhelmina Braunschweig, Inst Anorgan & Analyt Chem, Hagenring 30, D-38106 Braunschweig, Germany. White, Peter S., Univ N Carolina, Dept Chem, CB 3290, Chapel Hill, NC 27599 USA. Hohenberger, Johannes; Sutter, Joerg; Meyer, Karsten, Univ Erlangen Nurnberg, Dept Chem & Pharm, Inorgan Chem, Egerlandstr 1, D-91058 Erlangen, Germany. Maron, Laurent, Univ Toulouse, INSA UPS LPCNO, CNRS LPCNO, 135 Ave Rangueil, F-31077 Toulouse, France.','author-email':'[email protected] [email protected]',da:'2018-12-05','doc-delivery-number':'ET8MH',eissn:'2041-6539','funding-acknowledgement':'Alexander von Humboldt Foundation; NSF [CHE-0615704]; Emmy Noether and Heisenberg program [WA 2513/2, WA 2513/6]; Humboldt Foundation','funding-text':'We thank the Alexander von Humboldt Foundation for a Feodor-Lynen Fellowship (M. D. W.) and Prof. Maurice Brookhart for providing financial support (through NSF Grant CHE-0615704) and laboratory facilities (M. D. W.) during the initial phase of this research program. Deutsche Forschungsgemeinschaft (DFG) is acknowledged for generous funding by the Emmy Noether and Heisenberg program (WA 2513/2 and WA 2513/6, respectively). LM is grateful to the Humboldt Foundation for a grant of experienced researcher and the Chinese Academy of Science. CalMip is also gratefully acknowledged for a generous computational grant.','journal-iso':'Chem. Sci.','keywords-plus':'FE2O2 DIAMOND CORE; STRUCTURAL-CHARACTERIZATION; DINITROGEN ACTIVATION; SULFUR CLUSTERS; SOLVENT PURIFICATION; MOLECULAR-STRUCTURES; ELECTRON-TRANSFER; 2FE-2S CLUSTERS; DOUBLE-BOND; FE-IVN','number-of-cited-references':'106',oa:'DOAJ Gold','orcid-numbers':'Meyer, Karsten/0000-0002-7844-2998 Daniliuc, Constantin G./0000-0002-6709-3673','research-areas':'Chemistry','researcherid-numbers':'Meyer, Karsten/G-2570-2012 Walter, Marc/E-4479-2012','times-cited':'4','unique-id':'ISI:000400553000098','usage-count-last-180-days':'4','usage-count-since-2013':'20','web-of-science-categories':'Chemistry, Multidisciplinary'\International audienceThe iron half-sandwich [Cp'Fe(mu-I)](2) (Cp' = 1,2,4-(Me3C)(3)C5H2, 1) reacts with the pseudohalides NCO-, SCN-, SeCN- and N-3(-) to give [Cp'Fe(mu-NCO)](2) (2), [Cp'Fe(mu-S)](2) (3), [Cp'Fe(mu-Se-2)](2) (4) and [Cp'Fe(mu-N)](2) (5), respectively. Various spectroscopic techniques including X-ray diffraction, solid-state magnetic susceptibility studies and Fe-57 Mossbauer spectroscopy were employed in the characterization of these species. Mossbauer spectroscopy shows a decreasing isomer shift with increasing formal oxidation state, ranging from Fe(II) to Fe(IV), in complexes 1 to 5. The sulfido-bridged dimer 3 exhibits strong antiferromagnetic coupling between the Fe(III) centers. This leads to temperature-independent paramagnetism (TIP) at low temperature, from which the energy gap between the ground and the excited state can be estimated to be 2J = ca. 700 cm(-1). The iron(IV) nitrido complex [Cp'Fe(mu-N)](2) (5) shows no reactivity towards H-2 (10 atm), but undergoes clean reactions with CO (5 bar) and XylNC (Xyl = 2,6-Me2C6H3) to form the diamagnetic isocyanate and carbodiimide complexes [Cp'Fe(CO)(2)(NCO)] (7) and [Cp'Fe(CNXyl)(2)(NCNXyl)] (8), respectively. All compounds were fully characterized, and density functional theory (DFT) computations provide useful insights into their formation and the electronic structures of complexes 3 and 5
Integration of expressed sequence tag data flanking predicted RNA secondary structures facilitates novel non-coding RNA discovery.
No full textMany computational methods have been used to predict novel non-coding RNAs (ncRNAs), but none, to our knowledge, have explicitly investigated the impact of integrating existing cDNA-based Expressed Sequence Tag (EST) data that flank structural RNA predictions. To determine whether flanking EST data can assist in microRNA (miRNA) prediction, we identified genomic sites encoding putative miRNAs by combining functional RNA predictions with flanking ESTs data in a model consistent with miRNAs undergoing cleavage during maturation. In both human and mouse genomes, we observed that the inclusion of flanking ESTs adjacent to and not overlapping predicted miRNAs significantly improved the performance of various methods of miRNA prediction, including direct high-throughput sequencing of small RNA libraries. We analyzed the expression of hundreds of miRNAs predicted to be expressed during myogenic differentiation using a customized microarray and identified several known and predicted myogenic miRNA hairpins. Our results indicate that integrating ESTs flanking structural RNA predictions improves the quality of cleaved miRNA predictions and suggest that this strategy can be used to predict other non-coding RNAs undergoing cleavage during maturation
Torque driven ferromagnetic swimmers
No full textThis is the author accepted manuscript. The final version is available from AIP Publishing via the DOI in this recordMicroscopic swimming devices hold promise for radically new applications in lab-on-a-chip and microfluidic technology, including diagnostics and drug delivery. In this paper, we realize a macroscopic single particle ferromagnetic swimmer experimentally and investigate its swimming properties. The flagella-based swimmer is comprised of a hard ferromagnetic head attached to a flexible tail. We investigate the dynamic performance of the swimmer on the air-liquid interface as a function of the external magnetic field parameters (frequency and amplitude of an applied magnetic field). We show that the speed of the swimmer can be controlled by manipulating the strength and frequency of the external magnetic field (<3.5 mT) and that the propagation direction has a dependence on parameters of the external magnetic field. The experimental results are compared to a theoretical model based on three beads, one of which having a fixed magnetic moment and the other two non-magnetic, connected via elastic filaments. The model shows sufficient complexity to satisfy the “non-reciprocity” condition and gives good agreement with experiment. Via a simple conversion, we also demonstrate a fluid pump and investigate the induced flow. This investigation paves the way to the fabrication of such swimmers and fluid pump systems on a micro-scale, promising a variety of microfluidic applications.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No. 665440. We also acknowledge support via the EPSRC Centre for Doctoral Training in Metamaterials (Grant No. EP/L015331/1)
Wnt/β-catenin controls follistatin signalling to regulate satellite cell myogenic potential
No full textAbstract
Background
Adult skeletal muscle regeneration is a highly orchestrated process involving the activation and proliferation of satellite cells, an adult skeletal muscle stem cell. Activated satellite cells generate a transient amplifying progenitor pool of myoblasts that commit to differentiation and fuse into multinucleated myotubes. During regeneration, canonical Wnt signalling is activated and has been implicated in regulating myogenic lineage progression and terminal differentiation.
Methods
Here, we have undertaken a gene expression analysis of committed satellite cell-derived myoblasts to examine their ability to respond to canonical Wnt/β-catenin signalling.
Results
We found that activation of canonical Wnt signalling induces follistatin expression in myoblasts and promotes myoblast fusion in a follistatin-dependent manner. In growth conditions, canonical Wnt/β-catenin signalling prime myoblasts for myogenic differentiation by stimulating myogenin and follistatin expression. We further found that myogenin binds elements in the follistatin promoter and thus acts downstream of myogenin during differentiation. Finally, ectopic activation of canonical Wnt signalling in vivo promoted premature differentiation during muscle regeneration following acute injury.
Conclusions
Together, these data reveal a novel mechanism by which myogenin mediates the canonical Wnt/β-catenin-dependent activation of follistatin and induction of the myogenic differentiation process
Theory of ferromagnetic microswimmers
No full textCopyright © 2011 Oxford University Press. This is a pre-copy-editing, author-produced PDF of an article accepted for publication in The Quarterly Journal of Mechanics and Applied Mathematics following peer review. The definitive publisher-authenticated version [Volume 64, Issue 3, pp. 239-263] is available online at: http://qjmam.oxfordjournals.org/content/64/3/239This paper considers the dynamics of a microscale swimmer based on two magnetic beads that are elastically coupled together. A time-varying external magnetic field is imposed that has two principal effects: one is to exert a torque on the magnetic beads. The second is to change the orientation of the magnetic field dipoles in one or both beads, depending on their ferromagnetic properties. This then creates an attraction or repulsion between the two dipoles. The combination of dipole attraction/repulsion, moderated by the elastic coupling, and torque gives motions that are not generally time reversible and can lead to unidirectional swimming, that is persistent motion in one direction, in a Stokes flow regime. The equations of motion for the swimmer are set up using a Lagrangian formulation and supplemented by equations giving the dipole orientation of the magnetic fields of the beads in the external field. The equations are non-dimensionalized and key parameters determined. Numerical simulations reveal a number of regimes that are studied using simplified models and multiple scale analysis. Approximate thresholds are obtained above which the swimmer moves in a closed path and below which the orientation is `trapped' giving unidirectional motion. Three mechanisms for such trapping are isolated and discussed
Erratum: Corrigendum: Inhibition of JAK-STAT signaling stimulates adult satellite cell function
No full text
