scholarly journals Effects of Dexamethasone Dose and Timing on Tissue-Engineered Skeletal Muscle Units

2018 ◽  
Vol 205 (4) ◽  
pp. 197-207 ◽  
Author(s):  
Alexie A. Larson ◽  
Brian C. Syverud ◽  
Shelby E. Florida ◽  
Brittany L. Rodriguez ◽  
Molly N. Pantelic ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Cell Proliferation ◽  
Force Production ◽  
Structure And Function ◽  
Tetanic Force ◽  
Time Points ◽  
Early Differentiation ◽  
Brdu Assay ◽  
And Function ◽  
Precise Time

Our lab showed that administration of dexamethasone (DEX) stimulated myogenesis and resulted in advanced structure in our engineered skeletal muscle units (SMU). While administration of 25 nM DEX resulted in the most advanced structure, 10 nM dosing resulted in the greatest force production. We hypothesized that administration of 25 nM DEX during the entire fabrication process was toxic to the cells and that administration of DEX at precise time points during myogenesis would result in SMU with a more advanced structure and function. Thus, we fabricated SMU with 25 nM DEX administered at early proliferation (days 0–4), late proliferation (days 3–5), and early differentiation (days 5–7) stages of myogenesis and compared them to SMU treated with 10 nM DEX (days 0–16). Cell proliferation was measured with a BrdU assay (day 4) and myogenesis was examined by immunostaining for MyoD (day 4), myogenin (day 7), and α-actinin (day 11). Following SMU formation, isometric tetanic force production was measured. An analysis of cell proliferation indicated that 25 nM DEX administered at early proliferation (days 0–4) provided 21.5% greater myogenic proliferation than 10 nM DEX (days 0–4). In addition, 25 nM DEX administered at early differentiation (days 5–7) showed the highest density of myogenin-positive cells, demonstrating the greatest improvement in differentiation of myoblasts. However, the most advanced sarcomeric structure and the highest force production were exhibited with sustained administration of 10 nM DEX (days 0–16). In conclusion, alteration of the timing of 25 nM DEX administration did not enhance the structure or function of our SMU. SMU were optimally fabricated with sustained administration of 10 nM DEX.

scholarly journals Cytoskeleton and Adhesion in Myogenesis

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Manoel Luís Costa
Keyword(s):  
Skeletal Muscle ◽  
Extracellular Matrix ◽  
Smooth Muscle ◽  
Muscle Function ◽  
Force Production ◽  
Structure And Function ◽  
Cytoskeletal Proteins ◽  
Skeletal Muscle Differentiation ◽  
And Function ◽  
Structural Adaptations

The function of muscle is to contract, which means to exert force on a substrate. The adaptations required for skeletal muscle differentiation, from a prototypic cell, involve specialization of housekeeping cytoskeletal contracting and supporting systems into crystalline arrays of proteins. Here I discuss the changes that all three cytoskeletal systems (microfilaments, intermediate filaments, and microtubules) undergo through myogenesis. I also discuss their interaction, through the membrane, to extracellular matrix and to other cells, where force will be exerted during contraction. The three cytoskeletal systems are necessary for the muscle cell and must exert complementary roles in the cell. Muscle is a responsive system, where structure and function are integrated: the structural adaptations it undergoes depend on force production. In this way, the muscle cytoskeleton is a portrait of its physiology. I review the cytoskeletal proteins and structures involved in muscle function and focus particularly on their role in myogenesis, the process by which this incredible muscle machine is made. Although the focus is on skeletal muscle, some of the discussion is applicable to cardiac and smooth muscle.

scholarly journals New Insights into the Structural Roles of Nebulin in Skeletal Muscle

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Coen A. C. Ottenheijm ◽  
Henk Granzier
Keyword(s):  
Skeletal Muscle ◽  
Thin Filament ◽  
Force Production ◽  
Nemaline Myopathy ◽  
Structure And Function ◽  
Filament Length ◽  
Thin Filaments ◽  
Muscle Structure ◽  
And Function

One important feature of muscle structure and function that has remained relatively obscure is the mechanism that regulates thin filament length. Filament length is an important aspect of muscle function as force production is proportional to the amount of overlap between thick and thin filaments. Recent advances, due in part to the generation of nebulin KO models, reveal that nebulin plays an important role in the regulation of thin filament length. Another structural feature of skeletal muscle that is not well understood is the mechanism involved in maintaining the regular lateral alignment of adjacent sarcomeres, that is, myofibrillar connectivity. Recent studies indicate that nebulin is part of a protein complex that mechanically links adjacent myofibrils. Thus, novel structural roles of nebulin in skeletal muscle involve the regulation of thin filament length and maintaining myofibrillar connectivity. When these functions of nebulin are absent, muscle weakness ensues, as is the case in patients with nemaline myopathy with mutations in nebulin. Here we review these new insights in the role of nebulin in skeletal muscle structure.

scholarly journals Essential Role of Septin 7 in Skeletal Muscle Structure and Function

2020 ◽  
Vol 118 (3) ◽  
pp. 258a
Author(s):  
Laszlo Csernoch ◽  
Mónika Gönczi ◽  
Zsolt Ráduly ◽  
László Szabó ◽  
Nóra Dobrosi ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Essential Role ◽  
Structure And Function ◽  
Muscle Structure ◽  
And Function

PROLONGED INTRAVENOUS INFUSION OF LABELLED IODOCOMPOUNDS IN THE RAT: [125I]IODIDE METABOLISM AND EFFECTS OF MODERATE DIETARY IODINE DEFICIENCY

1979 ◽  
Vol 82 (2) ◽  
pp. 227-234 ◽  
Author(s):  
VIPA BOONNAMSIRI ◽  
J. C. KERMODE ◽  
B. D. THOMPSON
Keyword(s):  
Skeletal Muscle ◽  
Iodine Deficiency ◽  
Intravenous Infusion ◽  
Structure And Function ◽  
Continuous Intravenous Infusion ◽  
Close Approximation ◽  
Faecal Excretion ◽  
And Function ◽  
Layer Chromatography ◽  
Secretion Rates

SUMMARY Radio-iodide was administered by prolonged continuous intravenous infusion to rats maintained under iodine-replete conditions and in moderate iodine deficiency. A close approximation to equilibrium labelling was thereby achieved. Labelled iodocompounds extracted from various tissues were analysed by thin-layer chromatography. Moderate iodine deficiency resulted in a slight increase in the ratio of mono-iodotyrosine to di-iodotyrosine in the thyroid. No change in the ratio of tri-iodothyronine (T3) to thyroxine (T4) was found in thyroid, plasma or skeletal muscle. Faecal excretion of T3 declined appreciably relative to that of T4. Under iodine-replete conditions the ratio of thyroidal secretion rates of T3 and T4 was estimated to be more than three times higher than the ratio of these iodocompounds within the thyroid. Heterogeneity of thyroglobulin structure and function may explain these observations.

scholarly journals Skeletal muscle hypertrophy and structure and function of skeletal muscle fibres in male body builders

2006 ◽  
Vol 570 (3) ◽  
pp. 611-627 ◽  
Author(s):  
Giuseppe D'Antona ◽  
Francesca Lanfranconi ◽  
Maria Antonietta Pellegrino ◽  
Lorenza Brocca ◽  
Raffaella Adami ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Hypertrophy ◽  
Structure And Function ◽  
Muscle Fibres ◽  
Male Body ◽  
Skeletal Muscle Hypertrophy ◽  
And Function ◽  
Skeletal Muscle Fibres

AML1 is expressed in skeletal muscle and is regulated by innervation

1994 ◽  
Vol 14 (12) ◽  
pp. 8051-8057
Author(s):  
X Zhu ◽  
J E Yeadon ◽  
S J Burden
Keyword(s):  
Skeletal Muscle ◽  
Acute Myeloid Leukemia ◽  
Electrical Activity ◽  
Myeloid Leukemia ◽  
Structure And Function ◽  
Denervated Muscle ◽  
Aml1 Gene ◽  
Low Levels ◽  
And Function ◽  
Acute Myeloid

Although most skeletal muscle genes are expressed at similar levels in electrically active, innervated muscle and in electrically inactive, denervated muscle, a small number of genes, including those encoding the acetylcholine receptor, N-CAM, and myogenin, are expressed at significantly higher levels in denervated than in innervated muscle. The mechanisms that mediate electrical activity-dependent gene regulation are not understood, but these mechanisms are likely to be responsible, at least in part, for the changes in muscle structure and function that accompany a decrease in myofiber electrical activity. To understand how muscle activity regulates muscle structure and function, we used a subtractive-hybridization and cloning strategy to identify and isolate genes that are expressed preferentially in innervated or denervated muscle. One of the genes which we found to be regulated by electrical activity is the recently discovered acute myeloid leukemia 1 (AML1) gene. Disruption and translocation of the human AML1 gene are responsible for a form of acute myeloid leukemia. AML1 is a DNA-binding protein, but its normal function is not known and its expression and regulation in skeletal muscle were not previously appreciated. Because of its potential role as a transcriptional mediator of electrical activity, we characterized expression of the AML1 gene in innervated, denervated, and developing skeletal muscle. We show that AML1 is expressed at low levels in innervated skeletal muscle and at 50- to 100-fold-higher levels in denervated muscle. Four AML1 transcripts are expressed in denervated muscle, and the abundance of each transcript increases after denervation. We transfected C2 muscle cells with an expression vector encoding AML1, tagged with an epitope from hemagglutinin, and we show that AML1 is a nuclear protein in muscle. AML1 dimerizes with core-binding factor beta (CBF beta), and we show that CGF beta is expressed at high levels in both innervated and denervated skeletal muscle. PEBP2 alpha, which is structurally related to AML1 and which also dimerizes with CBF beta, is expressed at low levels in skeletal muscle and is up-regulated only weakly by denervation. These results are consistent with the idea that AML1 may have a role in regulating gene expression in skeletal muscle.

scholarly journals Effects of Ovariectomy on Skeletal Muscle Structure and Function in Young Female Rats: Protective Effects of the Flavanol (−)‐Epicatechin

2020 ◽  
Vol 34 (S1) ◽  
pp. 1-1
Author(s):  
Viridiana Navarrrete ◽  
Marcos Ayala ◽  
Antonio Rodriguez ◽  
Francisco Villarreal ◽  
Israel Ramirez-Sanchez
Keyword(s):  
Skeletal Muscle ◽  
Young Female ◽  
Structure And Function ◽  
Female Rats ◽  
Protective Effects ◽  
Muscle Structure ◽  
And Function

Skeletal Muscle: A Brief Review of Structure and Function

2014 ◽  
Vol 96 (3) ◽  
pp. 183-195 ◽  
Author(s):  
Walter R. Frontera ◽  
Julien Ochala
Keyword(s):  
Skeletal Muscle ◽  
Structure And Function ◽  
And Function

scholarly journals Effect of increased serum 25(OH)D and calcium on structure and function of post-menopausal women: a pilot study

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
H. J. Hillstrom ◽  
R. Soeters ◽  
M. Miranda ◽  
S. I. Backus ◽  
J. Hafer ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fatigue ◽  
Repeated Measures ◽  
Vastus Lateralis ◽  
Structure And Function ◽  
Muscle Size ◽  
Menopausal Women ◽  
Post Menopausal ◽  
And Function

Abstract Summary The purpose was to determine if increasing serum 25(OH)D and calcium in postmenopausal women increased skeletal muscle size, strength, balance, and functional task performance while decreasing muscle fatigue. PCSA of the vastus lateralis increased and ascent of stairs time decreased after 6 months of increased serum 25(OH)D. Purpose The Institute of Medicine recommends ≥ 20 ng/ml of serum 25-hydroxyvitamin D [25(OH)D] for bone and overall health. Serum 25(OH)D levels have been associated with physical performance, postural sway, and falls. The purpose of this study was to determine if increasing postmenopausal women’s serum 25(OH)D levels from 20–30 ng/ml to 40–50 ng/ml improved skeletal muscle size, strength, balance, and functional performance while decreasing skeletal muscle fatigue. Methods Twenty-six post-menopausal women (60–85 years old) with baseline serum 25(OH)D levels between 20 and 30 ng/ml were recruited. Oral over-the-counter (OTC) vitamin D3 and calcium citrate were prescribed to increase subjects’ serum 25(OH)D to levels between 40 and 50 ng/ml, serum calcium levels above 9.2 mg/dl, and PTH levels below 60 pg/ml, which were confirmed at 6 and 12 weeks. Outcome measures assessed at baseline and 6 months included muscle physiological cross-sectional area (PCSA), muscle strength, postural balance, time to perform functional tasks, and muscle fatigue. Repeated measures comparisons between baseline and follow-up were performed. Results Nineteen subjects completed the study. One individual could not afford the time commitment for the repeated measures. Three individuals did not take their vitamin D as recommended. Two subjects were lost to follow-up (lack of interest), and one did not achieve targeted serum 25(OH)D. Vastus lateralis PCSA increased (p = 0.007) and ascent of stair time decreased (p = 0.042) after 6 months of increasing serum 25(OH)D levels from 20–30 ng/ml to 40–50 ng/ml. Isometric strength was unchanged. Anterior-posterior center of pressure (COP) excursion and COP path length decreased (p < 0.1) albeit non-significantly, suggesting balance may improve from increased serum 25(OH)D and calcium citrate levels. Conclusions Several measures of muscle structure and function were sensitive to elevated serum 25(OH)D and calcium levels indicating that further investigation of this phenomenon in post-menopausal women is warranted.

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