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Cross Bridges of GB Smooth Muscle Contraction
Published in Wenguang Li, Biliary Tract and Gallbladder Biomechanical Modelling with Physiological and Clinical Elements, 2021
Normally, smooth muscle contraction is based on the thick (myosin)-filament regulator mechanism, while the vertebrate striated muscles contraction is initiated by thin (actin)-filament control, where regulatory proteins (troponin and tropomyosin) limit the cross-bridge cycling until Ca2+ binds to troponin (Somlyo et al. 1988). However, in the absence of Ca2+, vertebrate smooth muscle contraction appears to be thin-filament regulated and cooperative (Somlyo et al. 1988; Haeberle 1999), which is achieved by the PKC pathway (Morgan and Gangopadhyay 2001). It has been tested that for GB smooth muscle stimulated by a high CCK dose the pathway is thick-filament regulation. At a low-dose CCK, because the thin-filament PKC pathway is very sensitive to low Ca2+ concentration, it adopts thin-filament mechanism (Yu et al. 1994, 1998).
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
The influence of electrical stimulation on myogenic behavior is best known as the force that facilitates and dictates muscle contraction, as demonstrated by Galvani, Aldini, Duchenne, and McWilliam. In the body, skeletal muscle contractile activity is controlled by the nerves where an action potential travels down the nerve to the nerve ending, resulting in the release of acetylcholine at the neuromuscular junction. This neurotransmitter binds to acetylcholine receptors on the sarcolemma of the muscle, resulting in the activation of sodium–potassium channels on the sarcolemma of muscle fibers, causing an influx of sodium ions. This influx causes an action potential that travels to the t-tubules and sarcoplasmic reticulum, where it induces calcium release to the cytoplasm. Calcium then binds to troponin on the tropomyosin complex and induces actin myosin filament sliding, resulting in muscle contraction. Direct electrical stimulation of skeletal muscle mimics the action potential induced by acetylcholine release, resulting in a release of calcium from the sarcoplasmic reticulum, leading to contraction. As such, the use of electrical stimulation for influencing myogenic behavior both in vivo and in vitro has great potential in medicine for the treatment of neuromuscular disorders, paralysis, and many other disorders involving skeletal, cardiac, and smooth muscles.
A Review of the Technologies and Methodologies Used to Quantify Muscle-Tendon Structure and Function
Published in Cornelius Leondes, Musculoskeletal Models and Techniques, 2001
Thin filaments are composed primarily of actin, tropomyosin, and troponin. Thin filaments are approximately 1 μm long and 8 nm in diameter. Each thin filament contains about 360 actin monomers. Each actin monomer consists of a single polypeptide chain.8 Actin monomers polymerize to form a double helix pattern with a repeat spacing of 5.5 nm.8,88 Because of symmetry and the spherical shape of the actin monomers, there exists a groove on either side of the helix chain. Each groove is filled by a series of tropomyosin-troponin complexes, each spanning a length of seven actin monomers (41 nm in length). There is one troponin molecule, approximately 26 nm long, for each tropomyosin molecule. The tropomyosin molecule forms an α-helical coiled coil structure. The troponin molecule can be further divided into troponins C, I, and T.88,108
Selenium nanoparticles stabilized by fungal chitosan with antibacterial activity – synthesis and characterization
Published in Particulate Science and Technology, 2023
Kuppuswamy Kavitha, Selvaraj Bharathi, Arumugam Rajalakshmi, Manickam Ramesh, Perumal Padmini, Gopal Suresh, Veerasamy Guruchandran, Mani Prakash, Rengarajulu Puvanakrishnan, Balasubramanian Ramesh
The sources of chitosan include crustacean shells and fungal cell walls. Among these, chitosan of fungal origin represents stable physicochemical properties. Further, chitosan extracted from fungi is protein-free and hence, no allergic reaction is observed. Instead, crustacean chitosan contains arginine kinase, tropomyosin, and myosin light chain that could cause allergy. Chitosan extraction from fungi is simple, while deproteinization or demineralization steps are involved in crustacean chitosan extraction (Abo Elsoud and El-Kady 2019). The major disadvantage of chitosan extraction from fungi is low yield. Hence, optimizing chitosan production from fungi is necessary to solve this problem. In this study, among the fungal isolates, Aspergillus sp. SS4 has produced the optimal amount of mycelial biomass (39.19 gL−1wet weight), dried chitosan (27.6 gL−1), and spectroscopic quantification (26 gL−1), and hence, it is selected for optimization studies. The 18s rRNA gene sequencing followed by BLAST analysis revealed that the chosen fungal strain was Aspergillus niger (Figure 1).
Banana peels as a cost effective substrate for fungal chitosan synthesis: optimisation and characterisation
Published in Environmental Technology, 2023
Kumaresan Priyanka, Mridul Umesh, Kathirvel Preethi
Chitosan, a mostly prevalent cationic polysaccharide next to cellulose, is a deacetylated product of chitin composed of glucosamine and N-acetyl glucosamine units linked through ß 1–4 glycosidic linkage. Chitin deacetylation equips hydroxyl and free amine groups that imparts a distinctive feature to chitosan that upholds their flexibility for modification and paves the way for ample applications. Their multifaceted characteristics like biodegradability, biocompatibility and excellent emulsifying properties have invigorated their consumption in diverse sectors such as wastewater treatment, pharmaceutical, food and agro industries which has proliferated their demand in the commercial sector. Till date, crustaceans’ shells are broadly employed for chitosan production which undergoes intense acid and alkali treatments resulting in the liberation of hazardous discards. Furthermore their seasonal availability and inconsistent characteristics coupled with sequence of downstream processes bounds their usage in commercial scale. To circumvent these disputes fungal biomass has churned as idyllic sources and postures to be a sustainable route for chitosan production. Unlike crustacean shells, fungal mycelium is free of allergic protein tropomyosin and other inorganic substances which fasten their biomedical applications [4]. Numerous fungal species including Aspergillus niger, Rhizopus oryza, Aspergillus terreus, Amylomyces rouxii, Mucor circinelloides and Fusarium calmorum have been examined for chitosan production.
Proteomic analysis of whole-body responses in medaka (Oryzias latipes) exposed to benzalkonium chloride
Published in Journal of Environmental Science and Health, Part A, 2020
Young Sang Kwon, Jae-Woong Jung, Yeong Jin Kim, Chang-Beom Park, Jong Cheol Shon, Jong-Hwan Kim, June-Woo Park, Sang Gon Kim, Jong-Su Seo
This study demonstrated that proteomic analysis is a potential tool to study the molecular and biological mechanisms underlying BAC toxicity in medaka. Proteomic analysis revealed that BAC significantly affected some key proteins involved in the cytoskeleton, the oxidative stress response, the nervous and endocrine systems, signaling pathways, and cellular proteolysis (Figure 4). The proteomic data obtained from this study contribute to current knowledge of BAC toxicity in aquatic fish species, and identify potential biomarkers for chronic BAC ecotoxicity monitoring. Proteomic analyzes showed no differences in protein expression between exposure doses of BAC. Overall, the present study is consistent with previous reports indicating that proteins involved in the cytoskeleton and oxidative stress response are affected by BAC exposure. For biomarker applications, we propose that upregulated myosin light chain, tropomyosin 1, actin, superoxide dismutase, peroxiredoxin 6, and glutathione S-transferase are candidate biomarkers for BAC ecotoxicity. To our knowledge, this is the first study using a proteomic approach to investigate the ecotoxicological effects of BAC in aquatic organisms, and the potential biomarkers identified will be useful for assessment of BAC contamination and toxicity in aquatic ecosystems. However, validation of ecotoxicity requires multiple biomarkers rather than a single biomarker because BAC activates a variety of stress responses in medaka. Therefore, these potential biomarkers may need to be further investigated before their application as specific biomarkers, considering the association with the nervous and endocrine systems, signaling pathways, and cellular proteolysis.