scholarly journals Degeneration and Regeneration of Murine Skeletal Neuromuscular Junctions after Intramuscular Injection with a Sublethal Dose of Clostridium sordellii Lethal Toxin

2004 ◽  
Vol 72 (6) ◽  
pp. 3120-3128 ◽  
Author(s):  
Julien Barbier ◽  
Michel R. Popoff ◽  
Jordi Molgó
Keyword(s):  
Skeletal Muscle ◽  
Intramuscular Injection ◽  
Neuromuscular Junctions ◽  
Muscle Fibers ◽  
Small Gtpases ◽  
Lethal Toxin ◽  
Sublethal Dose ◽  
Partial Recovery ◽  
Clostridium Sordellii ◽  
Skeletal Muscle Fibers

ABSTRACT Clostridium sordellii lethal toxin (LT), a 250-kDa protein which is the bacteria's major virulence factor, belongs to a family of large clostridial cytotoxins which glucosylate small GTP-binding proteins. Here, we report the results of our ex vivo analysis of the structure and function of skeletal neuromuscular tissue obtained from mice at various times after intramuscular injection of a sublethal dose of LT (0.25 ng/g of body wt). The toxin caused, within 24 h, pronounced localized edema, inflammation, myofibril disassembly, and degeneration of skeletal muscle fibers in the injected area, and it glucosylated the muscle tissue's small GTPases. Regeneration of the damaged fibers was evident 6 to 9 days postinjury and was completed by 60 days. The expression of dystrophin, laminin, and fast and neonatal myosin in regenerating fibers, detected by immunofluorescence microscopy, confirmed that LT does not impair the high regenerative capacity of murine skeletal muscle fibers. Functional studies revealed that LT affects muscle contractility and neuromuscular transmission. However, partial recovery of nerve-evoked muscle twitches and tetanic contractions was observed by day 15 postinjection, and extensive remodeling of the neuromuscular junction's nerve terminals and clusters of muscle acetylcholine receptors was still evident 30 days postinjection. In conclusion, to the best of our knowledge, this is the first report to characterize the degeneration and regeneration of skeletal neuromuscular tissue after in vivo exposure to a large clostridial cytotoxin. In addition, our data may provide an explanation for the severe neuromuscular alterations accompanying wound infections caused by C. sordellii.

scholarly journals Nucleus-specific translation and assembly of acetylcholinesterase in multinucleated muscle cells.

1990 ◽  
Vol 110 (3) ◽  
pp. 715-719 ◽  
Author(s):  
R L Rotundo
Keyword(s):  
Skeletal Muscle ◽  
Cell Surface ◽  
Neuromuscular Junctions ◽  
Muscle Fibers ◽  
Structural Basis ◽  
Multinucleated Cells ◽  
Skeletal Muscle Fibers ◽  
Nuclear Domains ◽  
Nerve Muscle ◽  
Polypeptide Chains

Multinucleated skeletal muscle fibers synthesize cell surface and secreted oligomeric forms of acetylcholinesterase (AChE) that accumulate at specialized locations on the cell surface, such as sites of nerve-muscle contact. Using allelic variants of the AChE polypeptide chains as genetic markers, we show that nuclei homozygous for either the alpha or beta alleles residing in chimeric myotubes preferentially translate their AChE mRNAs on their respective ERs. These results indicate that the events of transcription, translation, and assembly of this membrane protein are compartmentalized into nuclear domains in multinucleated cells, and provide the structural basis for the possible localized expression and regulation of synaptic components at the neuromuscular junctions of vertebrate skeletal muscle fibers.

Viscoelastic properties of cross bridges in cardiac muscle

1995 ◽  
Vol 268 (3) ◽  
pp. H987-H998
Author(s):  
M. E. De Winkel ◽  
T. Blange ◽  
B. W. Treijtel
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibers ◽  
Ventricular Myocardium ◽  
Partial Recovery ◽  
Cross Bridge ◽  
Skeletal Muscle Fibers ◽  
Freeze Dried ◽  
Length Changes ◽  
Cross Bridges ◽  
Ventricular Trabeculae

Tension responses of rat right ventricular trabeculae to fast length changes are measured with microsecond resolution to obtain information about elastic properties of ventricular myocardium. Responses of these isometrically mounted trabeculae at 22 degrees C to fast length changes completed within 30 microseconds at 22 degrees C to fast length changes completed within 30 microseconds were similar in shape to those of skeletal muscle fibers. Results of quantitative evaluation of responses are interpreted in terms of cross-bridge properties. An upper bound for the elastic range of cross bridges in trabeculae, derived from the maximal developed force during Ca2+ activation and from stiffness in rigor, has been estimated as 8.4 +/- 2.2 nm. Their working stroke, estimated from the tension loss in the rigor state due to a shortening and from tension remaining after (partial) recovery, was 20 +/- 4 nm. The estimated working stroke of cross bridges is about three times larger in trabeculae than in freeze-dried skeletal muscle fibers of the frog at 4 degrees C, which points to important differences between cross-bridge mechanisms of contraction in cardiac and skeletal muscle.

The “KIMWIPE” Effect in Ultra-Thin Cryosections

1985 ◽  
Vol 43 ◽  
pp. 458-459
Author(s):  
I. Taylor ◽  
P. Ingram ◽  
J.R. Sommer
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Muscle Fibers ◽  
Ice Crystals ◽  
Crystal Formation ◽  
Ice Crystal ◽  
Thin Sections ◽  
Skeletal Muscle Fibers ◽  
Freeze Dried ◽  
Ice Crystal Formation

In studying quick-frozen single intact skeletal muscle fibers for structural and microchemical alterations that occur milliseconds, and fractions thereof, after electrical stimulation, we have developed a method to compare, directly, ice crystal formation in freeze-substituted thin sections adjacent to all, and beneath the last, freeze-dried cryosections. We have observed images in the cryosections that to our knowledge have not been published heretofore (Figs.1-4). The main features are that isolated, sometimes large regions of the sections appear hazy and have much less contrast than adjacent regions. Sometimes within the hazy regions there are smaller areas that appear crinkled and have much more contrast. We have also observed that while the hazy areas remain still, the regions of higher contrast visibly contract in the beam, often causing tears in the sections that are clearly not caused by ice crystals (Fig.3, arrows).

Effect of External Calcium and other Divalent Cations on K+ Contractures in Denervated Slow Skeletal Muscle Fibers of the Frog

2019 ◽  
Author(s):  
Leonardo Hernández
Keyword(s):  
Skeletal Muscle ◽  
Binding Capacity ◽  
Divalent Cations ◽  
Muscle Fibers ◽  
Free Calcium ◽  
Slow Skeletal Muscle ◽  
Skeletal Muscle Fibers ◽  
Free Calcium Concentration ◽  
Chronic Denervation ◽  
Denervated Muscles

The influence of Ca2+ and other divalent cations on contractile responses of slow skeletal muscle fibers of the frog (Rana pipiens) under conditions of chronic denervation was investigated.Isometric tension was recorded from slow bundles of normal and denervated cruralis muscle in normal solution and in solutions with free calcium concentration solution or in solutions where other divalent cations (Sr2+, Ni2+, Co2+ or Mn2+) substituted for calcium. In the second week after nerve section, in Ca2+-free solutions, we observed that contractures (evoked from 40 to 80 mM-K+) of non-denervated muscles showed significantly higher tensions (p<0.05), than those from denervated bundles. Likewise, in solutions where calcium was substituted by all divalent cations tested, with exception of Mn2+, the denervated bundles displayed lower tension than non-denervated, also in the second week of denervation. In this case, the Ca2+ substitution by Sr2+ caused the higher decrease in tension, followed by Co2+ and Ni2+, which were different to non-denervated bundles, as the lowest tension was developed by Mn2+, followed by Co2+, and then Ni2+ and Sr2+. After the third week, we observed a recovery in tension. These results suggest that denervation altering the binding capacity to divalent cations of the voltage sensor.

scholarly journals Development of a human neuromuscular tissue-on-a-chip model on a 24-well-plate-format compartmentalized microfluidic device

Lab on a Chip ◽  
2021 ◽  
Author(s):  
Kazuki Yamamoto ◽  
Nao Yamaoka ◽  
Yu Imaizumi ◽  
Takunori Nagashima ◽  
Taiki Furutani ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Microfluidic Device ◽  
Motor Neurons ◽  
Muscle Fibers ◽  
Three Dimensional ◽  
Tissue Model ◽  
Skeletal Muscle Fibers

A three-dimensional human neuromuscular tissue model that mimics the physically separated structures of motor neurons and skeletal muscle fibers is presented.

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