Effects of Aging on Type II Muscle Fibers: A Systematic Review of the Literature

The authors conducted a systematic review of the literature for scientific articles in selected databases to determine the effects of aging on Type II muscle fibers in human skeletal muscles. They found that aging of Type II muscle fibers is primarily associated with a loss of fibers and a decrease in fiber size. Morphological changes with increasing age particularly included Type II fiber grouping. There is conflicting evidence regarding the change of proportion of Type II fibers. Type II muscle fibers seem to play an important role in the aging process of human skeletal muscles. According to this literature review, loss of fibers, decrease in size, and fiber-type grouping represent major quantitative changes. Because the process of aging involves various complex phenomena such as fiber-type coexpression, however, it seems difficult to assign those changes solely to a specific fiber type.

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Residual force enhancement in human skeletal muscles: A systematic review and meta-analysis

Journal of Sport and Health Science ◽

10.1016/j.jshs.2021.05.006 ◽

2021 ◽

Author(s):

Daiani de Campos ◽

Lucas B.R. Orssatto ◽

Gabriel S. Trajano ◽

Walter Herzog ◽

Heiliane de Brito Fontana

Keyword(s):

Systematic Review ◽

Skeletal Muscles ◽

Meta Analysis ◽

Force Enhancement ◽

Residual Force ◽

Residual Force Enhancement ◽

Human Skeletal Muscles

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Fiber Type-Specific Expression of Low-Density Lipoprotein Receptor-Related Protein 6 in Human Skeletal Muscles

Pathobiology ◽

10.1159/000357238 ◽

2014 ◽

Vol 81 (2) ◽

pp. 94-99 ◽

Cited By ~ 2

Author(s):

Ikuko Takeda ◽

Tetsuya Takahashi ◽

Kazuhide Ochi ◽

Takashi Kurashige ◽

Yukari Shinozaki ◽

...

Keyword(s):

Skeletal Muscles ◽

Fiber Type ◽

Low Density Lipoprotein ◽

Density Lipoprotein ◽

Lipoprotein Receptor ◽

Related Protein ◽

Specific Expression ◽

Density Lipoprotein Receptor ◽

Lipoprotein Receptor Related Protein ◽

Human Skeletal Muscles

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O760 CRIGLER-NAJJAR SYNDROME TYPE I AND TYPE II IN PREGNANCY: A CASE REPORT AND SYSTEMATIC REVIEW OF THE LITERATURE

International Journal of Gynecology & Obstetrics ◽

10.1016/s0020-7292(12)61190-4 ◽

2012 ◽

Vol 119 ◽

pp. S528-S528

Author(s):

J. Zollner ◽

T. Rudra ◽

C. Philipp ◽

R. Misra

Keyword(s):

Systematic Review ◽

Case Report ◽

Type I ◽

Syndrome Type ◽

Type Ii ◽

Review Of The Literature ◽

In Pregnancy

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Fiber type- and position-dependent expression of a myosin light chain-CAT transgene detected with a novel histochemical stain for CAT.

The Journal of Cell Biology ◽

10.1083/jcb.115.2.423 ◽

1991 ◽

Vol 115 (2) ◽

pp. 423-434 ◽

Cited By ~ 52

Author(s):

M J Donoghue ◽

J D Alvarez ◽

J P Merlie ◽

J R Sanes

Keyword(s):

Light Chain ◽

Transgene Expression ◽

Myosin Light Chain ◽

Fiber Type ◽

Muscle Fibers ◽

Single Type ◽

Regulatory Sequences ◽

Type I ◽

Type Ii ◽

Light Chain Gene

We recently generated and characterized transgenic mice in which regulatory sequences from a myosin light chain gene (MLC1f/3f) are linked to the chloramphenicol acetyltransferase (CAT) gene. Transgene expression in these mice is specific to skeletal muscle and graded along the rostrocaudal axis: adult muscles derived from successively more caudal somites express successively higher levels of CAT. To investigate the cellular basis of these patterns of expression, we developed and used a histochemical stain that allows detection of CAT in individual cells. Our main results are as follows: (a) Within muscles, CAT is detected only in muscle fibers and not in associated connective tissue, blood vessels, or nerves. Thus, the tissue specificity of transgene expression observed by biochemical assay reflects a cell-type specificity demonstrable histochemically. (b) Within individual muscles, CAT levels vary with fiber type. Like the endogenous MLC1f/3f gene, the transgene is expressed at higher levels in fast-twitch (type II) than in slow-twitch (type I) muscle fibers. In addition, CAT levels vary among type II fiber subtypes, in the order IIB greater than IIX greater than IIA. (c) Among muscles that are similar in fiber type composition, the average level of CAT per fiber varies with rostrocaudal position. This position-dependent variation in CAT level is apparent even when fibers of a single type are compared. From these results, we conclude that fiber type and position affect CAT expression independently. We therefore infer the existence of separate fiber type-specific and positionally graded transcriptional regulators that act together to determine levels of transgene expression.

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Prolonged exercise training increases intramuscular lipid content and perilipin 2 expression in type I muscle fibers of patients with type 2 diabetes

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00272.2012 ◽

2012 ◽

Vol 303 (9) ◽

pp. E1158-E1165 ◽

Cited By ~ 44

Author(s):

C. S. Shaw ◽

S. O. Shepherd ◽

A. J. M. Wagenmakers ◽

D. Hansen ◽

P. Dendale ◽

...

Keyword(s):

Type 2 Diabetes ◽

Exercise Training ◽

Fiber Type ◽

Muscle Fibers ◽

Whole Body ◽

Type I ◽

Type Ii ◽

Perilipin 2 ◽

Diabetes Patients

The aim of the present study was to investigate changes in intramuscular triglyceride (IMTG) content and perilipin 2 expression in skeletal muscle tissue following 6 mo of endurance-type exercise training in type 2 diabetes patients. Ten obese male type 2 diabetes patients (age 62 ± 1 yr, body mass index BMI 31 ± 1 kg/m2) completed three exercise sessions/week consisting of 40 min of continuous endurance-type exercise at 75% V̇o2 peak for a period of 6 mo. Muscle biopsies collected at baseline and after 2 and 6 mo of intervention were analyzed for IMTG content and perilipin 2 expression using fiber type-specific immunofluorescence microscopy. Endurance-type exercise training reduced trunk body fat by 6 ± 2% and increased whole body oxygen uptake capacity by 13 ± 7% ( P < 0.05). IMTG content increased twofold in response to the 6 mo of exercise training in both type I and type II muscle fibers ( P < 0.05). A threefold increase in perilipin 2 expression was observed from baseline to 2 and 6 mo of intervention in the type I muscle fibers only (1.1 ± 0.3, 3.4 ± 0.6, and 3.6 ± 0.6% of fibers stained, respectively, P < 0.05). Exercise training induced a 1.6-fold increase in mitochondrial content after 6 mo of training in both type I and type II muscle fibers ( P < 0.05). In conclusion, this is the first study to report that prolonged endurance-type exercise training increases the expression of perilipin 2 alongside increases in IMTG content in a type I muscle fiber-type specific manner in type 2 diabetes patients.

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Can Enhanced Peroxides Decrease the Side Effects of Tooth Bleaching? A Systematic Review of the Literature

International Journal of Experimental Dental Science ◽

10.5005/jp-journals-10029-1077 ◽

2014 ◽

Vol 3 (2) ◽

pp. 84-91

Author(s):

Boniek Borges ◽

Mariana Vale ◽

Felipe Afonso ◽

Isauremi Assunção

Keyword(s):

Systematic Review ◽

Side Effects ◽

Calcium Phosphate ◽

Adverse Effects ◽

Amorphous Calcium Phosphate ◽

Morphological Changes ◽

Potassium Nitrate ◽

Tooth Bleaching ◽

Review Of The Literature ◽

Bleaching Gels

ABSTRACT Adverse effects of tooth bleaching on dental structures remain a topic of discussion in the literature, and the search for protocols that reduce such reported adverse effects is ongoing. The goal of this systematic literature review was to determine whether the use of tooth bleaching gels with added minerals, such as fluoride, calcium, hydroxyapatite, potassium nitrate, amorphous calcium phosphate, and casein phosphopeptide-amorphous calcium phosphate, reduced the occurrence of the main adverse effects of tooth bleaching. The electronic database search identified 16 studies that evaluated the effects of bleaching gels with added minerals on enamel hardness and/or roughness, mineral loss, post-treatment sensitivity, morphological changes, and/or cohesive enamel strength. The findings of this review suggest that the addition of minerals to bleaching gels can contribute to the reduction of most adverse effects, mainly sensitivity, without affecting treatment efficiency. How to cite this article Borges B, Vale M, Afonso F, Assunção I. Can Enhanced Peroxides Decrease the Side Effects of Tooth Bleaching? A Systematic Review of the Literature. Int J Experiment Dent Sci 2014;3(2):84-91.

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Increase in S6K1 phosphorylation in human skeletal muscle following resistance exercise occurs mainly in type II muscle fibers

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00530.2005 ◽

2006 ◽

Vol 290 (6) ◽

pp. E1245-E1252 ◽

Cited By ~ 115

Author(s):

René Koopman ◽

Antoine H. G. Zorenc ◽

Rudy J. J. Gransier ◽

David Cameron-Smith ◽

Luc J. C. van Loon

Keyword(s):

Skeletal Muscle ◽

Resistance Exercise ◽

Human Skeletal Muscle ◽

Fiber Type ◽

Muscle Fibers ◽

Initiation Factor ◽

Exercise Session ◽

Type I ◽

Type Ii ◽

Postexercise Recovery

To investigate the in vivo effects of resistance exercise on translational control in human skeletal muscle, we determined the phosphorylation of AMP-activated kinase (AMPK), eukaryotic initiation factor 4E-binding protein (4E-BP1), p70/p85-S6 protein kinase (S6K1), and ribosomal S6 protein (S6). Furthermore, we investigated whether changes in the phosphorylation of S6K1 are muscle fiber type specific. Eight male subjects performed a single high-intensity resistance exercise session. Muscle biopsies were collected before and immediately after exercise and after 30 and 120 min of postexercise recovery. The phosphorylation statuses of AMPK, 4E-BP1, S6K1, and S6 were determined by Western blotting with phospho-specific and pan antibodies. To determine fiber type-specific changes in the phosphorylation status of S6K1, immunofluorescence microscopy was applied. AMPK phosphorylation was increased approximately threefold immediately after resistance exercise, whereas 4E-BP1 phosphorylation was reduced to 27 ± 6% of preexercise values. Phosphorylation of S6K1 at Thr421/Ser424 was increased 2- to 2.5-fold during recovery but did not induce a significant change in S6 phosphorylation. Phosphorylation of S6K1 was more pronounced in the type II vs. type I muscle fibers. Before exercise, phosphorylated S6K1 was predominantly located in the nuclei. After 2 h of postexercise recovery, phospho-S6K1 was primarily located in the cytosol of type II muscle fibers. We conclude that resistance exercise effectively increases the phosphorylation of S6K1 on Thr421/Ser424, which is not associated with a substantial increase in S6 phosphorylation in a fasted state.

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