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Electromagnetic Field Effects on Soft Tissues – Muscles and Tendons
Published in Marko S. Markov, James T. Ryaby, Erik I. Waldorff, Pulsed Electromagnetic Fields for Clinical Applications, 2020
Erik I. Waldorff, Nianli Zhang, James T. Ryaby, Andrew F. Kuntz
Feng, He et al. (2011) examined the effect of duration (10, 15, and 20 days) of PEMF exposure (50 Hz, 1 mT, 30 min/day) on rat bone marrow mesenchymal stem cell (rBMSC) differentiation into cardiomyocyte-like cells. Positive control groups were treated with 5-azacytidine (10 μmol/L for 1 day), a DNA methylation inhibitor which stimulates cardiac differentiation of stem cells (Kaur, Yang et al. 2014), while standard controls were cultured with standard media. Outcome measures included mRNA expression of cardiac troponin T (TNNT2) and alpha-actinin (ACTN2) as determined by RT-PCR. Results indicated that, as early as 10 days, PEMF induced a 15.78-fold and 4.92-fold increase in TNNT2 mRNA and ACTN2 mRNA expression, respectively, relative to control groups. This increase was similar to that of the positive control groups at 10 days.
Mechanobiology in Health and Disease in the Central Nervous System
Published in Jiro Nagatomi, Eno Essien Ebong, Mechanobiology Handbook, 2018
Theresa A. Ulrich, Sanjay Kumar
On the cellular level, the innate physiological response to CNS trauma or disease is related to mechanobiological phenomena in a number of interesting ways. For example, one of the hallmarks of astrocyte activation is increased expression of cytoskeletal intermediate filaments, including glial fibrillary associated protein, vimentin, and nestin, in addition to upregulation of focal adhesion proteins, such as vinculin, talin, and paxillin, and the actin-crosslinking protein alpha-actinin, implying that activated astrocytes should express a highly contractile phenotype [118,119,128]. The increase in tissue volume accompanying astrocyte hypertrophy and hyperplasia increases the stress on surrounding cells, as does secretion of additional ECM proteins, such as collagen IV and laminin [129], which subsequently form a scar of collagenous basement membrane that is thought to be one of the major impediments to axonal regeneration [130]. This local increase in stress can produce positive feedback to initiate further pathological changes, including enhanced expression of endothelin, a potent vasoconstrictor and astrocytic mitogen that is also associated with astrocyte activation in response to a variety of pathologies [116].
Electrical stimulation of cells derived from muscle
Published in Ze Zhang, Mahmoud Rouabhia, Simon E. Moulton, Conductive Polymers, 2018
Anita F. Quigley, Justin L. Bourke, Robert M. I. Kapsa
CNTs have also been used to generate electroactive skeletal muscle scaffolds. These scaffolds have been used to enhance myoblast differentiation via electrical stimulation (Ostrovidov et al. 2014). Similar to studies by Shin, CNTs have been blended with GelMA to create electrically conductive hydrogels for skeletal muscle myoblast growth and stimulation. Ahadian and colleagues (2014b) further refined this blend of polymers to produce vertically aligned CNTs within the gel via dielectrophoresis. These hydrogels were used to successfully differentiate myoblasts and apply electrical stimulation to myoblast populations, which significantly increased the expression of a number of genes associated with myotube maturation, including alpha-actinin and myosin heavy-chain isoforms. Interestingly, levels of gene expression were highest in gels with aligned fibers versus randomly aligned fibers. CNTs have also been blended with polyurethane and have been used to deliver electrical stimulation to skeletal muscle myoblast cultures, significantly increasing the level of myoblast differentiation (Sirivisoot and Harrison 2011).
Filament-motor protein system under loading: instability and limit cycle oscillations
Published in Soft Materials, 2021
Amir Shee, Subhadip Ghosh, Debasish Chaudhuri
In Figure 5, we show how the onset of stable limit cycle oscillations () depends on the number of MPs recruited for a given rigidity of the elastic loading. The plot uses parameter values corresponding to microtubule-kinesin MP assay, at an ATP concentration of mM. The minimum number of MPs required for the onset of spontaneous oscillations increases with the stiffness of the substrate. While the particular calculations are performed for microtubule-kinesin system, the physical mechanism is equally applicable for acto-myosin systems. Our simple setup has a parallel in the rigidity sensing by cells, where contractile acto-myosin system couples to the extra-cellular matrix (ECM) via an adhesion complex consisting of alpha-actinin and integrin .[26,27] The range of values used in Figure 5 belongs to the range of rigidities of sub-micron elastomeric pillars used in cell spreading experiments .[27] The cell may utilize an increase of processive myosin bundles, required for the onset of oscillations (tugging), as a strategy to sense the ECM stiffness .[27,28] In fact, larger multifilament assemblies of myosin is noted near more rigid substrate .[27]
The association of the ACTN3 R577X and ACE I/D polymorphisms with athlete status in football: a systematic review and meta-analysis
Published in Journal of Sports Sciences, 2021
Alexander B. T. McAuley, David C. Hughes, Loukia G. Tsaprouni, Ian Varley, Bruce Suraci, Thomas R. Roos, Adam J. Herbert, Adam L. Kelly
In accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) guidelines (Moher et al., 2009), the following search strategy was implemented. A comprehensive search of the Pubmed, SPORTDiscus, and MEDLINE databases was conducted on 3 March 2020. For ACTN3 the following Boolean search was used: ((football) OR (soccer)) AND (actn3) OR (alpha-actinin-3) OR (actinin-alpha-3) OR (R577X) OR (rs1815739)). For ACE the following Boolean search was used: ((football) OR (soccer)) AND (ace) OR (angiotensin I converting enzyme) OR (rs1799752) OR (rs13447447) OR (rs4341) OR (rs4646994)). Additionally, Google Scholar was searched using word combinations of the aforementioned Boolean searches, with no year restriction placed on any search. Furthermore, reference lists of the identified articles were searched for additional relevant studies. At the initial screening stage studies were included if they: (1) were primary cohort or case-control investigations; (2) presented ACTN3 R577X or ACE I/D genotype frequencies of footballers in isolation; and (3) were published in the English language. Therefore, studies were excluded if they: (1) were reviews; (2) presented ACTN3 R577X or ACE I/D genotype frequencies of footballers combined with other sports; and (3) were published in a language other than in English.
A review on the recent progress, opportunities, and challenges of 4D printing and bioprinting in regenerative medicine
Published in Journal of Biomaterials Science, Polymer Edition, 2023
Parvin Pourmasoumi, Armaghan Moghaddam, Saba Nemati Mahand, Fatemeh Heidari, Zahra Salehi Moghaddam, Mohammad Arjmand, Ines Kühnert, Benjamin Kruppke, Hans-Peter Wiesmann, Hossein Ali Khonakdar
In the physiological environments, both cells and biological macromolecules can sense mechanical stressors from a wide range of sources, including shear stress from blood flow, mechanical stress from the neighboring ECM, and contraction forces from neighboring cells. External forces generated from cells have distinct characteristics, which may be identified by variations in amplitude, direction, and dispersion [150, 151]. Integrins, which are the main receptors for cell binding, initiate the formation of focal adhesions (FAs) through adhesion to ECM proteins which then attach the integrins to the cytoskeleton's actin filaments with the aid of adaptor proteins in the initial stage of cell-ECM interaction (for instance, talin, alpha-actinin, vinculin) [152]. FAs have also been shown to stabilize attachment areas by interacting with various signaling proteins (for example, tyrosine kinase, RAS proteins, proto-oncogene tyrosine-protein kinase Src) in a synergistic manner [153]. As shown in Figure 6(a), the biochemical processes associated with cell adhesion, including spreading on the ECM or substrate and generating the contractile force in the cell after adhesion, are triggered using actin polymerization through the cell's trailing edges. These parts of cells stimulate biochemical processes that generate contractility after bonding and spreading on the ECM or surface. The forces mentioned above are transferred from outside of the cell via adherent junctions (cell-cell contact) and local adhesions (extracellular ECM-cell contact) combined [154]. These tensions, generated in the center of the cell body and are referred to as CTF, are transferred forward to the ECM by integrin and then returned to cytoskeletal proteins via biochemical signals from ECM proteins [155]. Accordingly, these adhesions and interactions can affect many biological mechanisms that control cellular activities, including wound healing, angiogenesis, metastasis, and inflammation [93]. Various reports have shown how cell-loaded 3 D microstructures can be generated using cellular tensile force (CTF) to induce self-folding of micromachined flat plates, also known as cell origami.