Toward a concept of the functional unit of mammalian skeletal muscle

1982 ◽  
Vol 242 (5) ◽  
pp. R411-R420 ◽  
Author(s):  
E. H. Bloch ◽  
A. S. Iberall
Keyword(s):  
Skeletal Muscle ◽  
Functional Data ◽  
Functional Unit ◽  
Average Diameter ◽  
Mammalian Skeletal Muscle ◽  
Muscle Bundle ◽  
Cross Sectional ◽  
Maximum Area ◽  
Motor End Plate ◽  
Definition Of

The current concepts for the functional unit of mammalian skeletal muscle are reviewed and shown to lack components that are required for determining the unit. To secure a definition for the functional unit, requisite criteria were selected, and the manner by which these criteria were used to define the functional unit are discussed. For deriving a definition of the unit the following values were obtained: the unit is associated with the total length of the muscle fiber, which may achieve a maximum length of 60 cm; it exhibits an average diameter of 40 micrometers/fiber; it is associated with a capillary net whose length (arteriole to venule) is about 750-1,000 micrometers max; the net exhibits a capillary-to-fiber ratio for long capillaries of approximately 1-1.5:1, with a transverse capillaries occurring approximately every 150 micrometers; and it has a fiber-to-motor end plate ratio of 1:1. The correlation between anatomic data and functional data indicate that a functional unit of muscle is delimited by about 1 mm2 of the cross-sectional area of a muscle bundle, since this is the maximum area under autonomic control of its particular arteriolar blood supply, the metabolic throttle that determines the power being expended by the muscle bundle.

scholarly journals Purification of desmin from adult mammalian skeletal muscle

1981 ◽  
Vol 195 (2) ◽  
pp. 345-356 ◽  
Author(s):  
J M O'Shea ◽  
R M Robson ◽  
M K Hartzer ◽  
T W Huiatt ◽  
W E Rathbun ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Average Diameter ◽  
Intermediate Filament Protein ◽  
Mammalian Skeletal Muscle ◽  
Cytoskeletal Function ◽  
10 Nm Filaments ◽  
And Function ◽  
Filament Protein

A method has been developed for preparation of purified desmin from mature mammalian (porcine) skeletal muscle. A crude desmin-containing fraction was prepared by modification of procedures used for isolation of smooth-muscle intermediate-filament protein [Small & Sobieszek (1977) J. Cell Sci. 23, 243-268]. The desmin was extracted in 1 M-acetic acid/20 mM-NaCl at 4 degrees C for 15h from the residue remaining after actomyosin extraction from washed myofibrils. Successive chromatography on hydroxyapatite and DEAE-Sepharose CL-6B in 6M-urea yielded desmin that was routinely more than 97% 55 000-dalton protein and that had no detectable actin contamination. Removal of urea by dialysis against 10mM-Tris/acetate (pH 8.5)/1 mM dithioerythritol and subsequent clarification at 134 000 g (rav. 5.9 cm) for 1 h results in a clear desmin solution. Dialysis of purified desmin against 100 mM-NaCl/1 mM-MgCl2/10 mM-imidazole/HCl, pH 7.0, at 2 degrees C resulted in the formation of synthetic desmin filaments have an average diameter of 9-11.5 nm. The present studies demonstrate that the relatively small amount of desmin in mature skeletal muscle can be isolated in sufficient quantity and purity to permit detailed studies of its properties and function. Although 10nm filaments have not been unequivocally demonstrated in mature muscle in vivo, that the purified skeletal-muscle desmin will form 10 nm filaments in vitro lends support to their possible existence and cytoskeletal function in mature skeletal-muscle cells.

Plasticity of myonuclear number in hypertrophied and atrophied mammalian skeletal muscle fibers

1995 ◽  
Vol 78 (5) ◽  
pp. 1969-1976 ◽  
Author(s):  
D. L. Allen ◽  
S. R. Monke ◽  
R. J. Talmadge ◽  
R. R. Roy ◽  
V. R. Edgerton
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibers ◽  
Mammalian Skeletal Muscle ◽  
Cross Sectional ◽  
Neuromuscular Activation ◽  
Neuromuscular Activity ◽  
Hindlimb Muscles ◽  
Slow Fiber ◽  
Fiber Size ◽  
Adult Cat

Although a mammalian skeletal muscle fiber may contain thousands of myonuclei, the importance of this number or the potential to modulate it in adult muscle has not been clearly demonstrated. Using immunohistochemistry and confocal microscopy, we examined the plasticity of myonuclear number and fiber size in isolated fast and slow fiber segments from adult cat hindlimb muscles in response to chronic alterations in neuromuscular activity and loading. Compared with slow fibers in the soleus of control cats, myonuclear number in presumably transformed fast fibers was 32% lower and fiber size was decreased 73% after elimination of neuromuscular activation for 6 mo by spinal isolation. Slow fibers in the soleus of spinal-isolated cats had smaller cross-sectional areas, whereas myonuclear number was not significantly different than that in the control cats. Myonuclear number in fast plantaris fibers was more than threefold higher and fiber size was 2.8-fold higher after 3 mo of functional overload compared with the plantaris of control cats. Compared with control slow plantaris fibers, myonuclear number and fiber size also increased in overloaded slow plantaris fibers. These results demonstrate that changes in myonuclear number are associated with changes in myosin type and suggest that modulations in the amount of available DNA may be a factor in regulating cytoplasmic volume of muscle fibers in response to chronic changes in neuromuscular activity.

Effect of extracellular osmolality on cell volume and resting metabolism in mammalian skeletal muscle

2007 ◽  
Vol 292 (5) ◽  
pp. R1994-R2000 ◽  
Author(s):  
AnaMaria Antolic ◽  
Rosemarie Harrison ◽  
Chris Farlinger ◽  
Naomi M. Cermak ◽  
Sandra J. Peters ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Water Content ◽  
Cell Volume ◽  
Muscle Model ◽  
Type I ◽  
Mammalian Skeletal Muscle ◽  
Type Ii ◽  
Cross Sectional ◽  
Hyperosmotic Condition ◽  
Muscle Types

The purpose of the present investigation was to establish an in vitro mammalian skeletal muscle model to study acute alterations in resting skeletal muscle cell volume. Isolated, whole muscles [soleus and extensor digitorum longus (EDL)] were dissected from Long-Evans rats and incubated for 60 min in Sigma medium 199 (1 g of resting tension, bubbled with 95% O2-5% O2, 30 ± 2°C, and pH 7.4). Medium osmolality was altered to simulate hyposmotic (190 ± 10 mmol/kg) or hyperosmotic conditions (400 ± 10 mmol/kg), whereas an isosmotic condition (290 ± 10 mmol/kg) served as a control. After incubation, relative water content of the muscle decreased with hyperosmotic and increased with hyposmotic condition in both muscle types ( P < 0.05). The cross-sectional area of soleus type I and type II fibers increased ( P < 0.05) in hyposmotic, whereas hyperosmotic exposure led to no detectable changes. The EDL type II fiber area decreased in the hyperosmotic condition and increased after hyposmotic exposure, whereas no change was observed in EDL type I fibers. Furthermore, exposure to the hyperosmotic condition in both muscle types resulted in decreased muscle ATP and phosphocreatine ( P < 0.05) contents and increased creatine and lactate contents ( P < 0.05) compared with control and hyposmotic conditions. This isolated skeletal muscle model proved viable and demonstrated that altering extracellular osmolality could cause acute alterations in muscle water content and resting muscle metabolism.

scholarly journals Incidence Correction Factors for Moderate and Severe Acute Child Malnutrition From 2 Longitudinal Cohorts in Mali and Burkina Faso

2020 ◽  
Vol 189 (12) ◽  
pp. 1623-1627
Author(s):  
Francisco M Barba ◽  
Lieven Huybregts ◽  
Jef L Leroy
Keyword(s):  
Burkina Faso ◽  
Low Income ◽  
Severe Acute Malnutrition ◽  
Acute Malnutrition ◽  
Cross Sectional ◽  
Incidence Data ◽  
Moderate Acute Malnutrition ◽  
Cluster Randomized ◽  
Definition Of ◽  
Mid Upper Arm Circumference

Abstract Child acute malnutrition (AM) is an important cause of child mortality. Accurately estimating its burden requires cumulative incidence data from longitudinal studies, which are rarely available in low-income settings. In the absence of such data, the AM burden is approximated using prevalence estimates from cross-sectional surveys and the incidence correction factor $K$, obtained from the few available cohorts that measured AM. We estimated $K$ factors for severe acute malnutrition (SAM) and moderate acute malnutrition (MAM) from AM incidence and prevalence using representative cross-sectional baseline and longitudinal data from 2 cluster-randomized controlled trials (Innovative Approaches for the Prevention of Childhood Malnutrition—PROMIS) conducted between 2014 and 2017 in Burkina Faso and Mali. We compared K estimates using complete (weight-for-length z score, mid-upper arm circumference (MUAC), and edema) and partial (MUAC, edema) definitions of SAM and MAM. $K$ estimates for SAM were 9.4 and 5.7 in Burkina Faso and in Mali, respectively; K estimates for MAM were 4.7 in Burkina Faso and 5.1 in Mali. The MUAC and edema–based definition of AM did not lead to different $K$ estimates. Our results suggest that $K$ can be reliably estimated when only MUAC and edema-based data are available. Additional studies, however, are required to confirm this finding in different settings.

scholarly journals Knowledge and Practice of Health Professionals in the Management of Dysphagia

2021 ◽  
Vol 18 (4) ◽  
pp. 2139
Author(s):  
Eduardo Sánchez-Sánchez ◽  
Ylenia Avellaneda-López ◽  
Esperanza García-Marín ◽  
Guillermo Ramírez-Vargas ◽  
Jara Díaz-Jimenez ◽  
...  
Keyword(s):  
Healthcare Providers ◽  
Cross Sectional Study ◽  
Clinical Settings ◽  
Sectional Study ◽  
Swallowing Disorder ◽  
Cross Sectional ◽  
Anonymous Questionnaire ◽  
Knowledge And Practice ◽  
Definition Of ◽  
Management Of Dysphagia

The aim of this study was to determine healthcare providers’ knowledge and practices about dysphagia. A descriptive cross-sectional study was carried out based on a self-administered and anonymous questionnaire addressed to healthcare providers in Spain. A total of 396 healthcare providers participated in the study. Of these, 62.3% knew the definition of dysphagia as a swallowing disorder. In addition, up to 39.2% of the participants reported that they did not know whether the EatingAssessmentTool (EAT-10) dysphagia screening test was usedin their own clinical settings. Similarly, up to 49.1% of them did not know the ClinicalExaminationVolume-Viscosity (MECV-V) method. Nearly all participants (98.8%) reported that thickeners must be used forall liquids administered to patients. A higher percentage of respondents based the choice of texture on patient’s tolerance (78.2%) rather than on the MECV-V result (17.3%). In addition,76.4% of the professionals had witnessed a bronchoaspiration; after it, 44.4% (n = 175) of them reported the appearance of pneumonia, and 14.5% (n = 57) the death of the patient (p = 0.005). The participants revealeda moderate/low knowledge ofthe definition, diagnosis, and clinical management of liquid dysphagia, which indicates some room for improvements.

scholarly journals Food Consumption Determinants and Barriers for Healthy Eating at the Workplace—A University Setting

Foods ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 695
Author(s):  
João P. M. Lima ◽  
Sofia A. Costa ◽  
Teresa R. S. Brandão ◽  
Ada Rocha
Keyword(s):  
Food Consumption ◽  
Healthy Eating ◽  
Nutritional Value ◽  
Perceived Barriers ◽  
Cross Sectional ◽  
Meal Quality ◽  
Main Determinants ◽  
Definition Of ◽  
Self Administered Questionnaire ◽  
University Setting

Background: A wide variety of social, cultural and economic factors may influence dietary patterns. This work aims to identify the main determinants of food consumption and barriers for healthy eating at the workplace, in a university setting. Methods: A cross-sectional observational study was conducted with 533 participants. Data were obtained through the application of a self-administered questionnaire that included socio-demographic information, food consumption determinants and the main perceived barriers for healthy eating at the workplace. Results: The respondents identified “price” (22.5%), “meal quality” (20.7%), and “location/distance” (16.5%). For women, the determinant “availability of healthy food options” was more important than for men (p < 0.001). The food consumption determinants at the workplace most referred to by respondents were related to the nutritional value. Smell, taste, appearance and texture, and good value for money, were also considered important for choosing food at the workplace. Respondents referred to work commitments and lack of time as the main barriers for healthy eating at the workplace. Conclusions: Identification of determinants involved in food consumption, and the barriers for healthy eating, may contribute to a better definition of health promotion initiatives at the workplace aiming to improve nutritional intake.

Ex Vivo assessment of competent strut coverage after coronary stenting by optical coherence tomography

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
R Bhoite ◽  
H Jinnouchi ◽  
F Otsuka ◽  
Y Sato ◽  
A Sakamoto ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Predictive Value ◽  
Ex Vivo ◽  
High Sensitivity ◽  
Optical Coherence ◽  
Cross Sectional ◽  
Neointimal Thickness ◽  
Stent Strut ◽  
Oct Imaging ◽  
Definition Of

Abstract Background In many studies, struts coverage is defined as &gt;0 mm of tissue overlying the stent struts by optical coherence tomography (OCT). However, this definition has never been validated using histology as the “gold standard”. The present study sought to assess the appropriate cut-off value of neointimal thickness of stent strut coverage by OCT using histology. Methods OCT imaging was performed on 39 human coronary arteries with stents from 25 patients at autopsy. A total of 165 cross-sectional images from 46 stents were co-registered with histology. The optimal cut-off value of strut coverage by OCT was determined. Strut coverage by histology was defined as endothelial cells with at least underlying two layers of smooth muscle cells. Considering the resolution of OCT is 10–20 μm, 3 different cut-off values (i.e. at ≥20, ≥40, and ≥60 μm) were assessed. Results A total of 2235 struts were evaluated by histology. Eventually, 1216 struts which were well-matched struts were analyzed in this study. By histology, uncovered struts were observed in 160 struts and covered struts were observed in 1056 struts. The broadly used definition of OCT-coverage which does not consider neointimal thickness yielded a poor specificity of 37.5% and high sensitivity 100%. Of 3 cut-off values, the cut-off value of &gt;40 μm was more accurate as compared to &gt;20 and &gt;60 mm [sensitivity (99.3%), specificity (91.0%), positive predictive value (98.6%), and negative predictive value (95.6%)] Conclusion The most accurate cut-off value was ≥40 μm neointimal thickness by OCT in order to identify stent strut coverage validated by histology. Funding Acknowledgement Type of funding source: None

Sign in / Sign up

Export Citation Format

Share Document