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Muscle Types (muscle + type)

Distribution by Scientific Domains

Life Sciences	55%
Chemistry	33%

Selected Abstracts

Rapid loss of motor nerve terminals following hypoxia,reperfusion injury occurs via mechanisms distinct from classic Wallerian degeneration

JOURNAL OF ANATOMY, Issue 6 2008
Becki Baxter
Abstract Motor nerve terminals are known to be vulnerable to a wide range of pathological stimuli. To further characterize this vulnerability, we have developed a novel model system to examine the response of mouse motor nerve terminals in ex vivo nerve/muscle preparations to 2 h hypoxia followed by 2 h reperfusion. This insult induced a rapid loss of neurofilament and synaptic vesicle protein immunoreactivity at pre-synaptic motor nerve terminals but did not appear to affect post-synaptic endplates or muscle fibres. The severity of nerve terminal loss was dependent on the age of the mouse and muscle type: in 8,12-week-old mice the predominantly fast-twitch lumbrical muscles showed an 82.5% loss, whereas the predominantly slow-twitch muscles transversus abdominis and triangularis sterni showed a 57.8% and 27.2% loss, respectively. This was contrasted with a > 97% loss in the predominantly slow-twitch muscles from 5,6-week-old mice. We have also demonstrated that nerve terminal loss occurs by a mechanism distinct from Wallerian degeneration, as the slow Wallerian degeneration (Wlds) gene did not modify the extent of nerve terminal pathology. Together, these data show that our new model of hypoxia,reperfusion injury is robust and repeatable, that it induces rapid, quantitative changes in motor nerve terminals and that it can be used to further examine the mechanisms regulating nerve terminal vulnerability in response to hypoxia,reperfusion injury. [source]

DATA ANALYTICAL METHODOLOGIES IN THE DEVELOPMENT OF A VOCABULARY FOR EVALUATION OF MEAT QUALITY

JOURNAL OF SENSORY STUDIES, Issue 6 2002
M.G. O'SULLIVAN
ABSTRACT Pork patties from M. longissimus dorsi and M. psoas major were used by a sensory panel to develop a descriptive vocabulary to describe warmed-over flavor development. The patties were made from meat from animals supplemented with one of four dietary treatments, (I) control diet, (II) supplemental iron (7 g iron (II) sulfate/kg feed), (III) supplemental vitamin E (200 mg dl-,-tocopherol acetate/kg of feed) and (IV) supplemental vitamin E + supplemental iron. The sample set used for training reflected the variation in muscle type and degree of warmed-over flavor development (day 1 and 5). The sensory terms selected had to be relevant to the samples, discriminate between the samples, have cognitive clarity and be nonredundant. Based on these selection criteria an initial training list of 36 sensory terms consisting of odors, flavors, basic tastes and aftertastes was developed in a pretrial using experts with product knowledge. This list constituted the start of training the panel. Principle Component Analysis (PCA) and assessor suggestions were used for reducing the number of terms and after 5 days of training this list was reduced to 21 sensory terms. The discriminative ability of the sensory panel improved over the course of sensory training and was quantified by using the mean assessor signal to noise ratios (S/N) for the sensory terms for each training session. This signal to noise ratio is essentially the total initial variance divided by the residual cross-validated variance. Subsequent detailed multivariate analysis found that the bilinear descriptor leverage was a particularly efficient method for term reduction. [source]

Effects of muscle type on beef taste-traits assessed by an electric sensing system

ANIMAL SCIENCE JOURNAL, Issue 5 2010
Koichi CHIKUNI
ABSTRACT To assess the role of muscle fiber type in beef taste-traits, we analyzed cooked meats from bovine masseter, diaphragm, psoas major, longissimus thoracis, and semitendinosus muscles with an electric taste sensing system (INSENT SA402B). The system is composed of five taste sensors of polymer membranes fixing different lipids. The sensors, CT0, CA0, AAE, C00 and AE1 are designed to respond to the individual tastes of salty, sour, umami, bitter and astringent, respectively. The system found significant differences in the converted outputs of CA0 (cvCA0), C00 (cvC00) and AE1 (cvAE1) among the bovine muscles. The slow-type muscles (masseter and diaphragm) showed lower cvCA0, higher cvC00, and higher cvAE1 than did the fast-type muscles (psoas major, longissimus thoracis, and semitendinosus). Lactic acid content was different among muscle types and was highly related to the cvCA0 output and pH. carbonyl compounds and free fatty acids were higher in the slow-type muscles. Free fatty acids were major components causing the difference in the C00 output among the muscle types. Iron content was also different among the muscle types and related to the cvC00 and cvAE1 outputs. These results suggested that the muscle fiber type affects the beef taste characteristics. [source]

AMP-activated protein kinase in contraction regulation of skeletal muscle metabolism: necessary and/or sufficient?

ACTA PHYSIOLOGICA, Issue 1 2009
T. E. Jensen
Abstract In skeletal muscle, the contraction-activated heterotrimeric 5,-AMP-activated protein kinase (AMPK) protein is proposed to regulate the balance between anabolic and catabolic processes by increasing substrate uptake and turnover in addition to regulating the transcription of proteins involved in mitochondrial biogenesis and other aspects of promoting an oxidative muscle phenotype. Here, the current knowledge on the expression of AMPK subunits in human quadriceps muscle and evidence from rodent studies suggesting distinct AMPK subunit expression pattern in different muscle types is reviewed. Then, the intensity and time dependence of AMPK activation in human quadriceps and rodent muscle are evaluated. Subsequently, a major part of this review critically examines the evidence supporting a necessary and/or sufficient role of AMPK in a broad spectrum of skeletal muscle contraction-relevant processes. These include glucose uptake, glycogen synthesis, post-exercise insulin sensitivity, fatty acid (FA) uptake, intramuscular triacylglyceride hydrolysis, FA oxidation, suppression of protein synthesis, proteolysis, autophagy and transcriptional regulation of genes relevant to promoting an oxidative phenotype. [source]

Ultrastructural analysis of the smooth-to-striated transition zone in the developing mouse esophagus: Emphasis on apoptosis of smooth and origin and differentiation of striated muscle cells

DEVELOPMENTAL DYNAMICS, Issue 3 2005
Jürgen Wörl
Abstract The exact mechanism of smooth-to-striated muscle conversion in the mouse esophagus is controversial. Smooth-to-striated muscle cell transdifferentiation vs. distinct differentiation pathways for both muscle types were proposed. Main arguments for transdifferentiation were the failure to detect apoptotic smooth and the unknown origin of striated muscle cells during esophageal myogenesis. To reinvestigate this issue, we analyzed esophagi of 4-day-old mice by electron microscopy and a fine-grained sampling strategy considering that, in perinatal esophagus, the replacement of smooth by striated muscle progresses craniocaudally, while striated myogenesis advances caudocranially. We found numerous (1) apoptotic smooth muscle cells located mainly in a transition zone, where smooth intermingled with developing striated muscle cells, and (2) mesenchymal cells in the smooth muscle portion below the transition zone, which appeared to give rise to striated muscle fibers. Taken together, these results provide further evidence for distinct differentiation pathways of both muscle types during esophagus development. Developmental Dynamics 233:964,982, 2005. © 2005 Wiley-Liss, Inc. [source]

Parvalbumin deficiency in fast-twitch muscles leads to increased ,slow-twitch type' mitochondria, but does not affect the expression of fiber specific proteins

FEBS JOURNAL, Issue 1 2006
Peter Racay
Parvalbumin (PV), a small cytosolic protein belonging to the family of EF-hand calcium-binding proteins, is highly expressed in mammalian fast-twitch muscle fibers. By acting as a ,slow-onset' Ca2+ buffer, PV does not affect the rapid contraction phase, but significantly contributes to increase the rate of relaxation, as demonstrated in PV,/, mice. Unexpectedly, PV,/, fast-twitch muscles were considerably more resistant to fatigue than the wild-type fast-twitch muscles. This effect was attributed mainly to the increased fractional volume of mitochondria in PV,/, fast-twitch muscle, extensor digitorum longus, similar to levels observed in the slow-twitch muscle, soleus. Quantitative analysis of selected mitochondrial proteins, mitochondrial DNA-encoded cytochrome oxidase c subunit I and nuclear DNA-encoded cytochrome oxidase c subunit Vb and F1-ATPase subunit , revealed the PV,/,tibialis anterior mitochondria composition to be almost identical to that in wild-type soleus, but not in wild-type fast-twitch muscles. Northern and western blot analyses of the same proteins in different muscle types and in liver are indicative of a complex regulation, probably also at the post-transcriptional level. Besides the function in energy metabolism, mitochondria in both fast- and slow-twitch muscles act as temporary Ca2+ stores and are thus involved in the shaping of Ca2+ transients in these cells. Previously observed altered spatio-temporal aspects of Ca2+ transients in PV,/, muscles are sufficient to up-regulate mitochondria biogenesis through the probable involvement of both calcineurin- and Ca2+/calmodulin-dependent kinase II-dependent pathways. We propose that ,slow-twitch type' mitochondria in PV,/, fast muscles are aimed to functionally replace the slow-onset buffer PV based on similar kinetic properties of Ca2+ removal. [source]

Proteome analysis of early post-mortem changes in two bovine muscle types: M. longissimus dorsi and M. semitendinosis

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 3 2006
Xiaohong Jia
Abstract To study early post-mortem changes in muscle tissues from bull calves, cytosole proteins from two muscles: M. longissimus dorsi (LD) and M. semitendinosis (ST) at 0 and 24,h after slaughter were analysed by 2-DE. Principal component analysis (PCA) and rotation testing were used to analyse the protein patterns in the two muscles in order to select protein spots that were significantly different at the two time-points. Selected proteins were identified by MALDI-TOF/TOF. Five proteins, namely cofilin, lactoylglutathione lyase, substrate protein of mitochondrial ATP-dependent proteinase SP-22, HSP 27 and HSP20, were changed in both LD and ST muscles during post-mortem storage. Fifteen additional protein changes were observed in either LD or ST muscles, and some of these changes have not previously been observed to change during post-mortem storage of bovine muscles. Further studies will reveal the relevance of these biomarkers for meat quality. [source]

Effects of muscle type on beef taste-traits assessed by an electric sensing system

Continence and some properties of the urethral striated muscle of male greyhounds

BJU INTERNATIONAL, Issue 3 2000
B.A. Van Der Werf
Objective To determine the properties of the striated muscle of the greyhound (dog) urethra and to consider its role in maintaining continence. Materials and methods The thickness of the muscle layers and the muscle types were determined by examining sections stained with haematoxylin and eosin or Masson's trichrome. These factors were correlated with the mechanical and electrical responses of muscle strips to nerve stimulation, and compared with muscle from other breeds of dog and other parts of the animal. Results The striated muscle formed ,70% of the membranous urethra and was predominantly (68%) type IIa muscle (i.e. fast but fatigue-resistant). The mean resting membrane potential was ,74 mV; nerve stimulation produced an action potential with a mean amplitude of 97 mV and contraction lasting about 200 ms. All responses were abolished by d -tubocurarine. The contractions were well maintained with continuous or intermittent stimulation. The properties were intermediate between those of the anconeus (slow) and the extensor carpi radialis (fast) muscles. Conclusions The distribution, fibre type and contractile characteristics would enable the striated urethral muscle to maintain tension for continence at rest and provide additional continence during sprints. [source]