M-protein from chicken pectoralis muscle: isolation and characterization.
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Amino Acids↗
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Distribution of connectin (titin), nebulin and alpha-actinin at myotendinous junctions of chicken pectoralis muscles: an immunofluorescence and immunoelectron microscopic study.
The distribution of connectin (titin), nebulin and alpha-actinin in the areas of myotendinous junctions of chicken pectoralis muscles was examined by immunocytochemical methods. Staining with antibodies against connectin (4C9, SM1 and P1200) and nebulin formed 'doublets' flanking nonterminal Z-bands; near the end of muscle fibres 'singlets' were seen within the terminal sarcomere on the side adjacent to the terminal Z-bands. The apical regions of muscle processes, where no myosin filaments are present although actin filaments exist, were reactive with anti-nebulin but not with anti-connectin. Antibodies against pectoralis (skeletal muscle type) alpha-actinin stained non terminal Z-bands and that against gizzard (smooth muscle type) the sarcolemma. Terminal Z-bands were unreactive with both of these antibodies. These findings indicate that, although terminal and nonterminal Z-bands differ in their molecular composition, connectin and nebulin filaments appear to link myosin and actin filaments, respectively, to both Z-band types.
Actinin↗
Morphometric analysis of capillary geometry in pigeon pectoralis muscle.
The objective of the study was to examine the relationship(s) between the size and the geometry of the capillary network in the flight muscle of pigeon (Columbia livia). To this end, we used morphometry to analyze the degree of anisotropy (i.e., orientation) of capillaries with respect to the axis of the muscle fibers in perfusion-fixed samples of pigeon pectoralis muscles with large difference in capillary density. Capillary number per fiber cross-sectional area (range, 1,491-5,680 mm-2) depended on fiber size (aerobic fibers, 304-782 microns 2; glycolytic, 1,785-2,444 microns 2), as well as sarcomere length (1.69-2.20 microns), and the relative sectional area of aerobic and glycolytic fibers (aerobic, 42-84% of total fiber area). The degree of tortuosity of capillaries, i.e., their bending or sinuosity relative to the muscle fiber axis, was primarily a function of sarcomere length. In spite of large differences in capillary density, capillary orientation at a given sarcomere length was remarkably similar among samples. In addition to capillaries running parallel to the muscle fiber axis, a unique arrangement of branches running perpendicular to the muscle fiber axis was found in all samples. This arrangement yielded a large circumferential distribution of capillary surface around the muscle fibers. Compared to mammalian limb muscles examined over a 10-fold range of capillary density (range, 450-4,670 mm-2), the degree of anisotropy of capillaries was greater in all samples of pigeon M. pectoralis. In the pigeon, there was no increase in the amount of capillary surface area available for exchange per microvessel as a result of a greater degree of capillary tortuosity in samples with larger capillary density (capillary number per fiber cross-sectional area greater than 4,000 mm-2), as compared to samples with a capillary density less than 4,000 mm-2.
Animals↗
Novel thick filament protein of chicken pectoralis muscle: the 86 kd protein. I. Purification and characterization.
A new thick-filament-associated protein, the 86 kd protein, of chicken pectoralis major muscle was isolated from a crude C-protein preparation by a method similar to that used to purify H-protein from rabbit skeletal muscle. However, the protein with an apparent Mr of 86,000 and 370,000 as estimated by gel electrophoresis and gel permeation, respectively, is not related to C-protein and differs from rabbit H-protein by its elution behaviour from hydroxyapatite columns, by its molecular weight, ultraviolet light spectrum, amino acid composition and localization, and by its amount present in myofibrils. The amino acid composition reveals a high content of proline and gel permeation indicates an either highly asymmetric or polymeric structure of the molecule. Antibodies raised in rabbits against the 86 kd protein were demonstrated by double immunodiffusion and immunoblotting experiments to be specific for this protein. They show no cross-reactivity with any other myofibrillar protein of chicken pectoralis muscle, e.g. myosin, M-band proteins, titin or C-protein, nor did they exhibit a significant cross-reactivity with H-protein from rabbit. The 86 kd protein, which has been purified also by antibody affinity chromatography from a freshly prepared Guba-Straub extract of washed myofibrils, is a specific myofibrillar component located within each half of the A-band.
Amino Acids↗
Comparison of chicken genotypes: myofiber number in pectoralis muscle and myostatin ontogeny.
This study was performed to evaluate breast muscle development in chicken genotypes divergently selected for muscularity. In the first experiment, 2 commercial broiler lines (a high breast yield, HBY, and a normal breast yield broiler strain-cross, NBY) and a Leghorn line were grown up to 35 d to evaluate BW, breast weight, and breast yield. At 7 and 21 d of age, pectoralis muscle was used to estimate myofiber density (MFD, number of myofibers per mm2) and total apparent myofiber number (MFN). In the second experiment, the ontogeny of myostatin was determined from broiler- and Leghorn-type chick embryos, at embryonic days 1 to 20 (E1 to E20), using reverse transcription (RT)-PCR. As expected, the Leghorn line had lower BW, breast weight, and breast yield than broiler lines. The HBY line showed higher breast yield at all ages evaluated, but lower BW at 21 and 35 d than the NBY line. The Leghorn line had 45% higher MFD than broilers, which indicates an increased cross-sectional area of the myofibers in broiler lines. No MFD difference was observed between the broiler strains (P > 0.05). The myofiber number of broilers was more than twice that of Leghorns and HBY had 10% higher MFN than the NBY line. Myofiber number was correlated to BW (r = 0.58), breast weight (r = 0.58), and breast yield (r = 0.69). Conversely, MFD showed negative correlation with BW, breast weight, and breast yield (r = -0.85, -0.83, and -0.88, respectively). No effect of genotype or interaction between genotype and embryonic age was observed for myostatin expression. This study showed that broilers have higher MFN in the breast muscles than Leghorn-type chickens, and that high breast yield of broiler strains may be due to increased MFN. Higher muscularity of broilers, as compared with Leghorns, was not attributed to lower expression of myostatin during embryonic development.
Animals↗
Slow-type C-protein in dystrophic chicken fast pectoralis muscle.
C-protein isoform expression in hereditary dystrophic chicken skeletal muscle was compared with that in normal chicken muscle during postnatal development by immunocytochemical and immunoblot methods. In the pectoralis muscle (PM) of both normal and dystrophic chicken, slow- and fast-type C-proteins were coexpressed in the vast majority of myofibers at neonatal age, but the slow C-protein disappeared, leaving continued expression of only the fast-type C-protein as muscle development progressed up to 2 weeks posthatch. In the dystrophic chicken PM, however, myofibers containing slow-type C-protein reappeared about 1 month posthatch and increased in number with the progression of muscular dystrophy. We conclude that C-protein isoform expression in dystrophic myofibers resembles that in neonatal myofibers and that the expression of slow-type C-protein can be seen as a marker for chicken muscular dystrophy.
Animals↗
A modified pectoralis muscle flap for closure of postpneumonectomy esophagopleural fistula: technique and results.
In surgical treatment of late postpneumonectomy esophagopleural fistula, closure of the empyema space is of prime importance. A wide thoracoplasty and ample decapitation of the empyema cavity allow sufficient room for a modified pectoralis muscle flap, which provides sufficient mass to obliterate the entire empyema cavity. We present the cases of 2 patients in whom an esophagopleural fistula occurring 3 and 16 years after pneumonectomy was successfully closed by this method.
Adult↗
In vivo pectoralis muscle force-length behavior during level flight in pigeons (Columba livia)
For the first time, we report in vivo measurements of pectoralis muscle length change obtained using sonomicrometry combined with measurements of its force development via deltopectoral crest strain recordings of a bird in free flight. These measurements allow us to characterize the contractile behavior and mechanical power output of the pectoralis under dynamic conditions of slow level flight in pigeons Columba livia. Our recordings confirm that the pigeon pectoralis generates in vivo work loops that begin with the rapid development of force as the muscle is being stretched or remains nearly isometric near the end of the upstroke. The pectoralis then shortens by a total of 32 % of its resting length during the downstroke, generating an average of 10.33.6 J kg-1 muscle (mean s.d.) of work per cycle for the anterior and posterior sites recorded among the five animals. In contrast to previous kinematic estimates of muscle length change relative to force development, the sonomicrometry measurements of fascicle length change show that force declines during muscle shortening. Simultaneous measurements of fascicle length change at anterior and posterior sites within the same muscle show significant (P<0.001, three of four animals) differences in fractional length (strain) change that averaged 1912 %, despite exhibiting similar work loop shape. Length changes at both anterior and posterior sites were nearly synchronous and had an asymmetrical pattern, with shortening occupying 63 % of the cycle. This nearly 2:1 phase ratio of shortening to lengthening probably favors the ability of the muscle to do work. Mean muscle shortening velocity was 5.381.33 and 4.881.27 lengths s-1 at the anterior and posterior sites respectively. Length excursions of the muscle were more variable at the end of the downstroke (maximum shortening), particularly when the birds landed, compared with highly uniform length excursions at the end of the upstroke (maximum lengthening). When averaged for the muscle as a whole, our in vivo work measurements yield a mass-specific net mechanical power output of 70. 2 W kg-1 for the muscle when the birds flew at 5-6 m s-1, with a wingbeat frequency of 8.7 Hz. This is 38 % greater than the value that we obtained previously for wild-type pigeons, but still 24-50 % less than that predicted by theory.
Journal Article↗
Structural change in muscles of the dystrophic chicken. II. Progression of the histopathology in the pectoralis muscle.
Dystrophic (D) and normal (N) chicken pectoral muscle was analysed for histopathological differences from the embryo (day 20) through to the mature adult stage. A variety of indices of structural changes were used, to express the progression quantitatively. At the embryonic stage, fibroblast numbers (but not satellite cell numbers) are increased in D. D shows fibre hypertrophy discernible from about 4 days after hatching. Other abnormalities of fibre size and shape appear in D from about 2 weeks onwards. Nuclei numbers and location change characteristically in D, compared to N, from about 4 days, and these differences subsequently become very prominent. Fibre splitting and phagocytosis become significant in D from about 2 weeks onwards and increase noticeably thereafter. The later stages in D, with gross loss of muscle fibres, are also described, in the pectoral and posterior latissimus dorsi muscles. The analyses show that some of the structural changes in D precede the discernible difference in fibre type composition which develops between D and N. The changes in the muscle used provide a basis for assessing the effects of drug treatments at various stages, including the early post-hatch period.
Age Factors↗
Heterogeneity of myosin heavy-chain expression in fast-twitch fiber types of mature avian pectoralis muscle.
The aims of this study are to investigate the diversity of myosin heavy-chain (MyHC) expression among avian fast-twitch fibers, and to test the hypothesis that dissimilar MyHC isoforms are found in each of the principal avian fast-twitch fiber types. MyHCs within the muscle fibers of the pectoralis of 31 species of bird are characterized using immunocytochemical methods. A library of 11 monoclonal antibodies previously produced against chicken MyHCs is used. The specificity of these antibodies for MyHCs in each of the muscles studied is confirmed by Western blots. The results show that avian fast-twitch glycolytic fibers and fast-twitch oxidative-glycolytic fibers can contain different MyHCs. Among the species studied, there is also a conspicuous variety of MyHC isoforms expressed. In addition, the results suggest that two epitopes are restricted to chickens and closely allied gallinaceous birds. There are no apparent correlations between between MyHC epitope and presupposed contractile properties. However, the presence of different isoforms in different fast-twitch fiber types suggests a correlation between isoform and contractile function.
Animals↗
Chest wall implants: their use for pectus excavatum, pectoralis muscle tears, Poland's syndrome, and muscular insufficiency.
Solid customized and prefabricated silicone implants have been used by the author for 15 years in a wide range of chest wall deformities. Chest wall implants are often used in males seeking to augment a muscularly deficient or underdeveloped chest; however, their greatest use has come in a variety of deformities both congenital and acquired, such as pectus excavatum, Poland's Syndrome, and pectoralis muscle tears. The implants can be either customized using a moulage technique or are prefabricated, manufactured implants which can be modified on the operating table to repair the contour deformity. The immediate postoperative problem of seroma and subcutaneous implant "show" has been minimized by careful planning, gentle technique, deep insertion, improved patient positioning on the operating room table, and the use of oral anti-inflammatory medications. The long-term results of these implants seem very satisfactory. The patients are usually physically active, and the implants show no long-term sequelae such as seroma, infection, displacement, or rupture.
Adolescent↗
Normal and dystrophic embryonic chicken pectoralis muscle cultures: I. Cell differentiation, protein synthesis, and enzyme levels.
Normal (line 200) and dystrophic (line 307) embryonic chicken pectoralis muscle cells were studied in cell culture over a period of 2 weeks. During the first 4 days, normal and dystrophic cultures exhibited similar developmental increases in the number of nuclei within multinucleated myotubes, however, dystrophic muscle cells degenerated approximately twice as fast as normal cells once the initial burst of myoblast fusion was complete. The apparent synthesis rate of nonmyofibrillar proteins was similar in normal aand dystrophic cells throughout development, but the apparent synthesis rates of myosin heavy chain and the myofibrillar protein fraction were 50%--90% higher in dystrophic muscle cultures once maturity had been reached (days 6--14). The specific activities of creatine kinase and phosphofructokinase were not affected by the dystrophic condition; however, specific activity of AMP-deaminase was depressed 25%--40% in the dystrophic muscle cultures.
AMP Deaminase↗
Comparison of three stretches for the pectoralis minor muscle.
Pectoralis minor adaptive shortening in healthy individuals is associated with altered scapular kinematics similar to the alterations demonstrated in individuals with subacromial impingement. This associative relationship suggests that stretching of the pectoralis minor may improve scapular kinematics and assist in the management of shoulder impingement. Several stretches for the pectoralis minor are used clinically, although it is not known which stretch optimally lengthens the muscle. The purpose of this analysis was to compare the mean length change for 3 pectoralis minor stretches. Fifty subjects without shoulder pathology were examined for the change in length of the pectoralis minor during 3 separate stretches by use of an electromagnetic motion-capture system. The stretches analyzed were a unilateral self-stretch, a supine manual stretch, and a sitting manual stretch. Each stretch was significantly different from the other two (df, 2/98; F ratio, 39.09; P < .00001), with the unilateral self-stretch demonstrating the greatest length change (2.24 cm), followed by the supine manual stretch (1.69 cm) and the sitting manual stretch (0.77 cm). Knowledge of the most effective method of elongating the pectoralis minor muscle may improve clinical decision making when targeting this anterior scapulothoracic muscle as part of intervention for or prevention of shoulder impingement.
Adult↗
The conjoined sternalis-pectoralis muscle flap in immediate tissue expander reconstruction after mastectomy.
The sternalis muscle is an accessory muscle of the anterior chest wall. This is a rare anatomic variant reported in approximately 8% of the population, with variation among races. While several anatomic studies of the sternalis muscle exist, nothing in the literature addresses the implications of this muscle on reconstruction of the breast after mastectomy. Based on several encounters of this muscle variant by the senior author over a 15-year period, we offer a strategy and rationale for dealing with this rare, but known, anatomic variant during immediate tissue expander reconstruction of the breast after mastectomy. First is the importance of recognizing the presence of a sternalis muscle, which may present in a variety of configurations. We offer our technique of conjoined sternalis-pectoralis muscle flap during tissue expander reconstruction of the breast. This allows for the creation of a larger, more properly placed submuscular pocket with adequate muscle coverage of the tissue expander. Our experience illustrates that the reconstructive surgeon must be familiar with the sternalis muscle and be prepared to adapt his or her technique for tissue expander placement when faced with this accessory muscle.
Adult↗
Specificity and development of innervation pattern of Xenopus pectoralis muscle.
Multielectrode recordings were used to identify and measure the axonal inputs to each end plate on contiguous surface fibers covering about 25% of the Xenopus pectoralis muscle in mature and developing animals. The mature innervation pattern was remarkably precise. Individual axons tended to innervate fibers of similar input resistance (R(in)) in compact motor units restricted to only a portion of the region studied. Motor units comprising fibers of similar R(in) overlapped mainly near their borders. Most fibers had two end plates. In more than 80% of these fibers, both end plates received input from the same axon. In 57%, this was the only input to both end plates. This implies a powerful mechanism for excluding or eliminating inputs from other axons. About 16% of the mature junctions showed focal polyneuronal innervation, with the weaker end plate potential component often less than 1 mV in noncurarized preparation. However, we have no evidence that the weaker inputs were being eliminated. During development, motor units became more compact, which was associated with synapse elimination; but from the earliest times studied, soon after metamorphosis when many fibers were adding second end plates, a majority of those that had two end plates were innervated at both sites by the same axon.
Aging↗
Acidic and basic protein contents in Gastrocnemii and pectoralis muscles of chick under denervation and work-induced stress conditions.
Biochemical estimation of acidic and basic proteins of chick gastrocnemii (G. externus, G. medius and G. internus) and pectoralis muscles has been done under normal, denervated and work stress conditions from 1-56 days of postnatal growth. The reciprocal relationship of the two protein groups is clearly established. It is evident that muscle denervation acts as a stimulant for proteosynthetic activities and probably may also be an inhibitory factor for protein degradative reactions. During work overload stress, the rapid growth of muscles has been related to high rate of contractile activity.
Animals↗
ROENTGEN DIAGNOSIS OF CONGENITAL ABSENCE OF PECTORALIS MUSCLES.
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Congenital Abnormalities↗
Regional differences in guinea pig pectoralis muscle. A histophysiological study.
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Acid Phosphatase↗