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PubMed1988

Resectable breast cancer: axillary dissection sparing pectoralis muscles and nerves.

In breast cancer surgery, axillary dissection is currently considered an essential step. Nevertheless, procedures commonly used include the resection of the pectoralis minor muscle and/or pectoralis nerves. Since 1984 we have performed axillary dissection by sparing both the pectoralis muscles and their nerves. In this paper we present the surgical technique. The comparison of the two groups with clinical N0 N1a assessment, the former of 103 patients submitted to this kind of surgical procedure, the latter (108 women) treated by resection of the pectoralis minor muscle, showed that the mean number of dissected lymph nodes in both procedures was superimposable.

Axilla↗

PubMed1983

Myosin isozymes in avian skeletal muscles. II. Fractionation of myosin isozymes from adult and embryonic chicken pectoralis muscle by immuno-affinity chromatography.

Chicken pectoralis consists primarily of large white fibres, which react exclusively with antibodies prepared against adult fast myosin. There is, however, a small region of uniformly red fibres which responds to antibodies against adult slow myosin as well as adult fast myosin. The myosin extracted from this red region is also heterogeneous as shown by the presence of both slow and fast light chains. By means of immunoadsorbents, it has been possible to separate the 'red myosin' into a 'fast' component and a 'slow' component. These two fractions have been characterized with respect to their light and heavy chain content by one-dimensional and two-dimensional gel electrophoresis. The myosin heavy chain was reduced to the smaller fragments required for electrophoresis by proteolytic degradation. We conclude from the electrophoretic patterns that the 'fast' and 'slow' myosin components from the pectoralis red region closely resemble the myosin from the white region of the pectoralis and the myosin from the slow anterior latissimus dorsi (ALD) muscle. The demonstration of a 'slow myosin' in adult pectoralis muscle raises the possibility that the crossreactivity of embryonic pectoralis myosin with anti-slow (ALD) myosin antibodies might be due to the presence of such slow components in embryonic chicken muscle. Direct isolation of a slow component from embryonic pectoralis was achieved by immunoadsorption, as described for adult mixed muscle myosin. Analysis of the subunit composition by gel electrophoresis shows an enrichment in adult-type slow light chains, but the heavy chain pattern is quite distinct from that of adult slow heavy chain. These studies suggest that several myosin isozymes exist in embryonic chicken pectoralis, but that none is identical to those myosins found in the different fibres of the adult pectoralis muscle.

Adenosine Triphosphatases↗

PubMed2005

Sonographic evaluation of injuries to the pectoralis muscles.

OBJECTIVE: Our aim was to show the application of high-resolution sonography for grading and defining athletic and nonathletic injuries to the pectoralis muscles. CONCLUSION: Sonography provides dynamic high-resolution imaging for the diagnosis and grading of injuries to the pectoralis muscles.

Accidental Falls↗

PubMed1998

Fiber capillarization and ultrastructure of pigeon pectoralis muscle after cold acclimation.

We investigated the effect of 2 months of exposure to cold conditions (0-5 C) on capillarization and on fiber size, distribution and ultrastructure in the pectoralis muscle of nine pigeons (Columbia livia; mean body mass 700 31 g) and compared the results with measurements from four control birds (mean mass 715 42 g) kept at normal ambient temperature (22-23 C) for the same period. Superficial and deep portions of the muscles, taken from the central area of the right or left pectoralis major muscle, were perfusion-fixed in situ, processed for electron microscopy and analyzed by morphometry. Aerobic fibers represented the vast majority of fibers (93 1 %, mean s.e.m.) in all samples. After cold-acclimation, fiber sectional area was reduced and capillary density increased proportionally. There was no change in the degree of orientation (anisotropy) of capillaries, capillary-to-fiber ratio or fiber type distribution compared with controls. The volume density of mitochondria and lipid droplets in aerobic fibers and capillary diameter increased in response to cold, while the linear relationship between capillary length per fiber volume and fiber mitochondrial volume density remained unchanged. Capillary surface area, intrafiber lipid deposition and fiber mitochondrial volume density were all correlated in cold-acclimated pigeons. The results indicate a close match between the aerobic capacity of the highly aerobic fibers of the pectoralis muscle and their vascularization to meet the increased energetic demand of shivering.

Acclimatization↗

PubMed2001

Pectoralis muscle performance during ascending and slow level flight in mallards (Anas platyrhynchos).

In vivo measurements of pectoralis muscle length change and force production were obtained using sonomicrometry and delto-pectoral bone strain recordings during ascending and slow level flight in mallards (Anas platyrhynchos). These measurements provide a description of the force/length properties of the pectoralis under dynamic conditions during two discrete flight behaviors and allow an examination of the effects of differences in body size and morphology on pectoralis performance by comparing the results with those of a recent similar study of slow level flight in pigeons (Columbia livia). In the present study, the mallard pectoralis showed a distinct pattern of active lengthening during the upstroke. This probably enhances the rate of force generation and the magnitude of the force generated and, thus, the amount of work and power produced during the downstroke. The power output of the pectoralis averaged 17.0 W kg(-)(1 )body mass (131 W kg(-)(1 )muscle mass) during slow level flight (3 m s(-)(1)) and 23.3 W kg(-)(1 )body mass (174 W kg(-)(1 )muscle mass) during ascending flight. This increase in power was achieved principally via an increase in muscle strain (29 % versus 36 %), rather than an increase in peak force (107 N versus 113 N) or cycle frequency (8.4 Hz versus 8.9 Hz). Body-mass-specific power output of mallards during slow level flight (17.0 W kg(-)(1)), measured in terms of pectoralis mechanical power, was similar to that measured recently in pigeons (16.1 W kg(-)(1)). Mallards compensate for their greater body mass and proportionately smaller wing area and pectoralis muscle volume by operating with a high myofibrillar stress to elevate mechanical power output.

Animals↗

PubMed1994

Pectoralis muscle morphology in the little brown bat, Myotis lucifugus: a non-convergence with birds.

Recent studies of muscle architecture demonstrate that many mammalian muscles are composed of short, interdigitating fibers. In addition, the avian pectoralis, a muscle capable of producing high frequency oscillations has been shown to possess a serially arranged pattern of muscle endplate in all sizes of birds studied. The pectoralis muscle of the little brown bat, Myotis lucifugus (Chiroptera: Vespertilionidae), is composed of fairly uniform fibers that span the length of the muscle and is characterized by a zone of motor endplates within the middle third of the muscle. The homogeneous fiber architecture of the bat pectoralis muscle is in contrast to the serial arrangement of endplates (and presumably muscle fibers) in the avian pectoralis in species equivalent in size to Myotis. The short fiber organization and motor endplate pattern observed in most birds is thus not a requisite design for flying vertebrates.

Animals↗

PubMed1998

Distribution of phosphate-activated glutaminase isozymes in the chicken: absence from liver but presence of high activity in pectoralis muscle.

The distribution of glutaminase expression in a uricotelic species, the chicken, has been examined using cDNA probes to the rat isozymes. The results suggest that chickens do not possess a glutaminase isozyme equivalent to the liver-type isozyme of mammalian liver. Measurements of enzymic activity also showed very low glutaminase activity in chicken liver. Extra-hepatic tissues in the chicken do express a glutaminase isozyme mRNA which is detected by rat kidney-type glutaminase cDNA. The abundance of this mRNA was highest in kidney and breast muscle and relatively abundant in brain, spleen and adipose tissue. Chicken small intestine expressed relatively low levels of the mRNA. The high level of glutaminase mRNA in chicken pectoralis muscle was accompanied by high glutaminase enzymic activity. In contrast, in mixed leg muscle glutaminase mRNA was barely detectable by Northern blot and glutaminase activity was relatively low. Starvation for 48 h resulted in a slight decrease in the activity of glutaminase in pectoralis muscle, but a large decrease in the relative abundance of the mRNA. The results suggest that in the chicken, hepatic glutamine hydrolysis is not quantitatively important, but skeletal muscle may be a major site of glutamine catabolism.

Animals↗

PubMed1992

The preservation of minor pectoralis muscle in axillary dissection for breast cancer: functional and cosmetic evaluation.

We have evaluated, in two groups of 50 patients each submitted to axillary dissection for breast cancer (10 mastectomies and 90 conservative procedures), the advantage of the preservation of the minor pectoralis muscle. This muscle was preserved in one group and removed in the other. Whereas in the immediate postoperative period complications (shoulder pain, functional impairment, quantity or duration of serum drainage from the axilla) were the same in the two groups, at longer follow-up (more than 6 months after surgery) the patients whose pectoralis minor muscle was preserved showed a reduction in the incidence of partial atrophy and fibrosis of the pectoralis major muscle. Patients treated with conservation of the pectoralis minor muscle showed this atrophy in 6% of cases vs 54% observed in the other patients. This fact may be related to disruption of the pectoral nerves, which are in close contact with the pectoralis minor during their course from the brachial plexus to the pectoralis major muscle.

Axilla↗

PubMed1990

Selective denervation of the Musculus pectoralis muscle in the chicken.

A surgical method for selective denervation was developed to facilitate investigations about the postmortem characteristics of denervated pectoralis muscles in chickens, Musculus (M.) pectoralis. The M. pectoralis was denervated in anesthetized chickens unilaterally or bilaterally by excising a 1-cm section of the nervus pectoralis as it branched from the N. medianoulnaris in the brachial plexus. Denervation resulted in significant (P less than .01) and consistent depression in the relative weight of M. pectoralis from the wk 2 through 17 postoperative. The relative weight of the functionally antagonistic M. supracoracoideus was unaffected by ipsilateral denervation of the M. pectoralis. The M. coracobrachialis acts in synergism with the M. pectoralis and displayed significant muscle atrophy at 4, 6, 8 and 17 wk postoperative in treatment groups where the ipsilateral M. pectoralis was denervated. Only the M. pectoralis displayed histological signs of denervation in transverse cryostat sections. Denervated tissue was characterized by atrophic and rounded muscle-fiber profiles, an increase in the endomysial and perimysial connective-tissue spaces, and leucocytes within degenerative perimysial nerves from 2 through 17 wk postoperative. Signs of denervation were distributed throughout seven zones sampled from the M. pectoralis. This study indicated that selective denervation of the M. pectoralis was achieved and that postoperative histology was necessary to accurately assess denervation.

Animals↗

PubMed1990

Regulation of glycolysis in the pectoralis muscles of seasonally acclimatized American goldfinches exposed to cold.

Regulation of glycolysis was assessed in winter- and summer-acclimatized goldfinches (Carduelis tristis). We exposed birds to a thermo-neutral temperature (30 degrees C), moderate cold (-15 degrees C), and severe cold (0 degrees C in an atmosphere of 21% O2-79% He), and then measured concentrations of glycogen, glycolytic intermediates, and citrate in the pectoralis muscles. Winter birds used less glycogen when exposed to moderate cold than did summer birds, confirming the carbohydrate sparing noted by Marsh and Dawson [Am. J. Physiol. 242 (Regulatory Integrative Comp. Physiol. 11): R563-R569, 1982]. However, depletion of muscle glycogen did not correlate with thermoregulatory failure in this study. Concentrations of glucose 6-phosphate and fructose 6-phosphate in the pectoralis muscles were approximately 1.9 and 0.3 mumol/g wet mass in birds exposed to thermoneutral temperatures. The levels of these intermediates fell 50-70% under conditions known to enhance flux through glycolysis as indicated by increased glucose turnover and glycogen depletion. This information identifies phosphofructokinase (PFK) as a major regulated step in glycolysis in these highly aerobic skeletal muscles. Winter birds maintained the inhibition of this step under conditions of moderate cold. However, concentrations of citrate, which have been hypothesized to be an important inhibitor of PFK, did not correlate with the observed pattern of inhibition. Therefore, if the enhanced beta-oxidative capacity of winter birds is important in the regulation of glycolysis, a mechanism other than the accumulation of citrate may be involved.

Acclimatization↗

PubMed1985

Novel thick filament protein of chicken pectoralis muscle: the 86 kd protein. II. Distribution and localization.

Antibodies specific for the novel 86 kd protein purified from chicken pectoralis myofibrils stained by indirect immunofluorescence the middle third of each half A-band of isolated myofibrils and myotubes. Pectoralis muscle 86 kd protein, like pectoralis C-protein, displayed a fibre-type specific distribution by being restricted to fast twitch fibres and absent in slow tonic and heart muscle fibres. This was demonstrated by immunoblotting experiments with tissue extracts and by immunofluorescence labelling of cryosections. In primary cell cultures prepared from embryonic chicken breast muscle, 86 kd protein, C-protein and myomesin were all detected in post-mitotic myoblasts where fluorescence was found in a cross-striated pattern along strands of nascent myofibrils. Fluorescence due to the 86 kd protein was restricted to myofibrils within myotubes and no significant labelling of the sarcoplasm was evident. Glycerinated fast twitch muscle fibres, after incubation with antibodies to 86 kd protein, revealed in each half of the A-band nine distinctly labelled stripes, spaced about 43 nm apart. Simultaneous incubation of fibres with antibodies against 86 kd protein and C-protein showed a co-localization of the seven C-protein stripes (stripes 5 to 11), with seven stripes of 86 kd protein. The two additional stripes (stripes 3 and 4) labelled by anti-86 kd antibody continued towards the M-band at the same periodicity from the last C-protein stripe (stripe 5). Thus, partial co-localization of two different thick filament proteins is demonstrated and the identity of transverse stripes at positions 3 and 4 attributed in part to the presence of the new 86 kd protein.

Animals↗

PubMed2004

Muscle (pectoralis major) protein turnover in young broiler chickens fed graded levels of lysine and crude protein.

An evaluation of muscle (pectoralis major) protein turnover using the phenylalanine flood dose technique was assessed in broiler chicks fed graded dietary lysine levels with CP at 170, 210, 250, and 290 g/kg diet. Chicks at 21 d old were injected with 1 mL/100 g BW of a phenylalanine solution (120 micromol L-[ring-2H5)]-phenylalanine). Muscle protein gain was assessed in chicks at 19 and 23 d of age. No differences were found in weight gain at lysine levels higher than 1.22% of the diet. Dietary lysine levels affected fractional synthesis rate (FSR, %/ d) of muscle with 170 and 210 g of CP/kg diet but not with 250 and 290 g of CP/kg. However, there was increasing FSR with increasing diet lysine levels at 290 g of CP/ kg. Breast muscle protein deposition (absolute growth rate, AGR, mg/d) reached a plateau with 1.22% dietary lysine at CP levels of 170,210, and 290 g/kg diet, confirming the observation on gross muscle weight. In terms of absolute synthesis rate/AGR with minimal absolute breakdown rate (ABR), the diet containing 210 g of CP/kg with 1.22% lysine was the most appropriate for chicks to 21 d. Levels of lysine influenced protein synthesis more so than protein degradation. These data suggest that both protein synthesis and breakdown increase at levels of dietary lysine and CP above those required for maximizing growth.

Animal Feed↗

PubMed1989

Myosin light chain 3 synthesis during chick pectoralis muscle development in ovo.

The level of myosin light chain 3 (LC3) in vertebrate skeletal muscle is developmentally regulated in a tissue-specific manner. We have used the RNA-cDNA hybridization assay to quantitate LC3 mRNA levels at various stages of chick pectoralis muscle development in ovo. The LC3 mRNA was found significantly in breast muscle only on Day 16 in ovo and later, the level of mRNA ranging from about 30 to 32% of that present in adult tissue. These values are in good agreement with the corresponding levels of LC3 in embryonic muscle. These results do not support the earlier reports that the protein and mRNA for LC3 accumulate in a noncoordinate manner in embryonic pectoralis muscle and they suggest that LC3 synthesis in ovo is regulated primarily at the transcriptional level.

Animals↗

PubMedDate not supplied

Skeletal muscle lysosomes: comparison of lysosomes from normal and dystrophic avian pectoralis muscle as a function of age.

The properties of skeletal muscle lysosomes from normal and dystrophic chickens were studied to assess their involvement in the dystrophic process. A method is described for isolation of a three-to-sevenfold purified lysosome fraction with 29-33% yield. Lysosomal enzymes in crude homogenates and isolated lysosome-enriched fractions from dystrophic muscle exhibit decreased latency for N-acetyl beta-D-glucosaminidase, acid phosphatase, and cathepsin D. However, no differences in the fragility of lysosomes in isolated lysosome-enriched fractions from normal and dystrophic muscle were observed using shear, sonication and detergent stress. Lower percent recovery, enrichment factor and percent latency of acid phosphatase compared to N-acetyl-beta-D-glucosaminidase and cathepsin D were observed from both normal and dystrophic muscle. These results are consistent with the presence of a significant amount of nonlysosomal acid phosphatase activity in skeletal muscle.

Acetylglucosaminidase↗

PubMed2001

Effect of vitamin E and selenium on resistance to oxidative stress in chicken superficial pectoralis muscle.

One-day-old chicks were reared using diets that differed in their vitamin E and/or selenium content. In chicks depleted of both selenium and vitamin E, signs of exudative diathesis on the superficial pectoralis muscle were observed. The purpose of this research was to determine the defective points of the antioxidant defense system, which made this tissue highly susceptible to nutritionally-induced oxidative stress. Vitamin E, and selenium in lower magnitude, were the factors that strikingly affected the course of mitochondrial lipid peroxidation. Animals fed diets deficient in vitamin E and selenium displayed the lowest reduced glutathione level and glutathione peroxidase activity. The decreased levels of reduced glutathione were not due to a defective activity of glutathione reductase, which was increased in both mitochondria and cytosol. The absence of vitamin E was linked to lowering of mitochondrial thiol levels. The Glutathione peroxidase/Cu,Zn-superoxide dismutase ratio was 2.8 in animals fed selenium and vitamin E, and decreased to 0.13 in animals deficient in both nutrients. This change was indicative of oxidant-induced damage mediated by hydrogen peroxide. Catalase activity increased in an attempt to counteract the decrease in glutathione peroxidase activity. The results obtained showed that alpha-tocopherol and Se deficiencies caused multiple alterations in the antioxidant system and adversely affected the redox state of chicken superficial pectoralis muscle.

Animals↗

PubMed2001

The mechanical power output of the pectoralis muscle of blue-breasted quail (Coturnix chinensis): the in vivo length cycle and its implications for muscle performance.

Sonomicrometry and electromyographic (EMG) recordings were made for the pectoralis muscle of blue-breasted quail (Coturnix chinensis) during take-off and horizontal flight. In both modes of flight, the pectoralis strain trajectory was asymmetrical, with 70 % of the total cycle time spent shortening. EMG activity was found to start just before mid-upstroke and continued into the downstroke. The wingbeat frequency was 23 Hz, and the total strain was 23 % of the mean resting length. Bundles of fibres were dissected from the pectoralis and subjected in vitro to the in vivo length and activity patterns, whilst measuring force. The net power output was only 80 W kg(-1) because of a large artefact in the force record during lengthening. For more realistic estimates of the pectoralis power output, we ignored the power absorbed by the muscle bundles during lengthening. The net power output during shortening averaged over the entire cycle was approximately 350 W kg(-1), and in several preparations over 400 W kg(-1). Sawtooth cycles were also examined for comparison with the simulation cycles, which were identical in all respects apart from the velocity profile. The power output during these cycles was found to be 14 % lower than during the in vivo strain trajectory. This difference was due to a higher velocity of stretch, which resulted in greater activation and higher power output throughout the later part of shortening, and the increase in shortening velocity towards the end of shortening, which facilitated deactivation. The muscle was found to operate at a mean length shorter than the plateau of the length/force relationship, which resulted in the isometric stress measured at the mean resting length being lower than is typically reported for striated muscle.

Animals↗

PubMedDate not supplied

Mammoplasty: breast fixation with dermoglandular mono upper pedicle flap under the pectoralis muscle.

A surgical procedure for breast fixation to avoid secondary ptosis of the lower quadrants and nipple-areola complex bascule and to maintain the breast upper pole projection is described and evaluated after long-term pexy and reduction mammoplasty. A superior monopedicle dermal-adipose-glandular flap with the areola-nipple complex placed in its base is mobilized and its extremity sutured to a "trapdoor" type of flap dissected in the pectoralis muscle. This procedure determines the permanent areola-nipple complex and the upper breast quadrant position, avoiding the common secondary breast ptosis, when the breast tissue is sutured to the pectoralis muscle. One thousand seven hundred patients have undergone this procedure in the last 15 years.

Adolescent↗

PubMed1996

Regeneration of specific innervation in Xenopus pectoralis muscle.

We investigated the motor unit organization and precision of reinnervation in the Xenopus pectoralis muscle following different manipulations, including crush or section of the posterior pectoralis nerve, foreign nerve innervation, and crush coupled with activity modulation or block. Most fibers have two neuromuscular junctions, and multielectrode recordings were used to identify the axonal origin of all inputs to both junctions on most or all fibers covering about 25% of the muscle surface. Following simple nerve crush, a highly organized innervation pattern was restored, indistinguishable from the normal pattern, including selective innervation of fibers of similar input resistance (R(in)), compact motor unit organization, and high incidence of exclusive innervation of both end plates on each fiber by the same axon (distributed mononeuronal innervation, or a/a pattern). Initial reinnervation was equally precise when nerve conduction in the regenerating nerve was blocked by tetrodotoxin. More distant or repeated nerve crush or nerve section delayed and reduced the precision of reinnervation, but the majority of fibers still received input to both end plates by the same axon, often in combination with others. A foreign nerve, the pectoralis sternalis, which in its own muscle forms only single end plates, showed less precise reinnervation, but still had an incidence of a/a innervation far above chance. These data imply the expression and recognition of remarkably precise chemospecific cues even in mature animals, superimposed on which is a further refinement by synapse elimination, probably based on an activity-dependent process.

Animals↗