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A patient suffering with myasthenia gravis was subjected to muscle biopsy of the deltoid and subsequently of the pectoralis muscle. Electron microscopic examination of the muscles revealed the scattered presence of Z-lines that were curiously orientated diagonally across the I band. This appears to be a coincidental finding, the significance of which is unknown and unreported at this time.
Locomotion was compared in an intact and in-vitro preparation of the adult mudpuppy (Necturus maculatus). The intact animals walked on an aquatic treadmill while in-vitro preparations were made to walk with a bath application of the excitatory amino acid NMA (N-methyl DL-aspartate). EMG recordings of shoulder muscles (pectoralis, latissimus dorsi, dorsalis scapulae, and procoracohumeralis) and elbow muscles (brachialis and extensor ulnae) were obtained from intact animals while recordings were made from only the elbow muscles in-vitro. The in-vitro preparation required magnesium in the bath to initiate and maintain locomotion, consistent with an NMDA mediated response. Also consistent with an NMDA response was the finding that glycine potentiated the NMA induced locomotion in-vitro. The range of cycle durations seen in-vitro was well within the range seen in the intact animal, while gait analysis demonstrated the similarity of intact and in-vitro locomotor cycles. In spite of these very similar locomotor patterns there are interesting differences in the patterned output seen in-vitro, such as the absence of a second burst in the brachialis muscle in-vitro.
Empyema continues to be an uncommon, frustrating, and potentially lethal complication of pneumonectomy. Between 1990 and 1994 we treated 16 cases of recalcitrant postpneumonectomy (partial or total) empyema with combinations of pulse lavage, sharp debridement, muscle flaps, myodermal flaps, and thoracoplasty. We performed 11 pectoralis muscle flaps, 6 serratus anterior muscle flaps, 9 latissimus dorsi muscle flaps, 6 rectus abdominis muscle flaps, and 1 trapezius muscle flap for an average of 2.1 muscle flaps per patient. There was 1 omental flap. Of these flaps, 2 were free and the rest pedicled. Ten of the muscle flaps carried deepithelialized cutaneous paddles, and 6 were larger than 150 cm3. Thoracoplasty was done in 11 patients to decrease the volume of the postpneumonectomy empyema cavity. Of 16 patients, 4 failed initially because of persistent bronchopleural fistula or infection but resolved after one additional procedure. There was 1 perioperative death, 3 reoperations for bleeding, 1 patient with upper extremity deep vein thromboses, 1 seroma, and 1 patient with significant postoperative pain syndrome. In order to determine the efficacy of different operative approaches, patients were retrospectively divided into two groups according to the number of operations using flaps needed to resolve their postpneumonectomy empyema. Group A required only one operation using flaps to eliminate the postpneumonectomy empyema. Group B required two operations using flaps to remedy the postpneumonectomy empyema. Group B operations were further classified into B1, for the first operation, and B2, for the second operation. No patient needed more than two operations using flaps. Three significant variables were identified, the number of muscle flaps, the number of ribs in any thoracoplasty, and the preoperative serum albumin level. The A and B2 groups had significantly more muscle flaps transposed (p = 0.006) and ribs resected (p = 0.0002) than the B1 group. These findings suggest that filling the postpneumonectomy empyema space with muscle and collapsing any remaining space by thoracoplasty were the most successful strategy. The B2 group's average albumin level was significantly higher (p = 0.03) than that in either the A or the B1 group, suggesting that improved nutrition may have played a role in the lack of recurrence. Our goals of single-stage closure and decontamination of empyema cavities were best achieved by following these principles: removal of infected and necrotic tissue using sharp debridement and pulsed lavage, repair of bronchopleural fistulas with muscle flaps, and minimization of the dead space with combinations of muscle flaps and thoracoplasty.
In the mirror of the pertinent literature, we present our experiences gained in 161 operations for pectus carinatum. The Type I (keel chest) deformity is corrected by bilateral resection of the costal cartilages, transverse osteotomy of the sternum, detachment of the xiphoid process, and resection of the lower end of the body of the sternum. The sternum is maintained in its corrected position by utilizing the pulling force of the rectus muscles through the reattached xiphoid and by tacking the pectoralis muscles together in front of the breast bone. Type II (pouter pigeon breast) is handled by double transverse osteotomy, chiseling off the protuberant portion of the strernomanuberial junction, and by supporting the lower sternal body with either the suspended xiphoid process or with Marlex mesh. Limited forms of Type III (asymmetrical or lateral pectus carinatum) are managed with simple resection of the involved cartilages only. If the anomaly is more extensive, bilateral resection of the cartilages and correction of the sternal axis is carried out.
Avian pectoralis muscle cells differentiated in vitro are mechanically stimulated by repetitive stretch-relaxation of the cell's substratum using a computerized mechanical cell stimulator device. Initiation of mechanical stimulation increases the efflux of creatine kinase from the cells during the first 8-10 h of activity, but the efflux rate returns to control levels after this time period. Decreased total cell protein content accompanies the temporary elevation of creatine kinase efflux. With continued mechanical stimulation for 48-72 h, total cell protein loss recovers and significantly increases in medium supplemented with serum and embryo extract. Myotube diameters increase and cell hyperplasia occurs in the stimulated cultures. In basal medium without supplements, mechanical activity prevents myotube atrophy but does not lead to cell growth. Mechanically induced growth is accompanied by significant increases in protein synthesis rates. The increases in protein synthesis and accumulation induced by mechanical stimulation are not inhibited by tetrodotoxin but are significantly reduced in basal medium without supplements. Mechanically stimulated cell growth is thus dependent on medium growth factors but independent of electrical activity.
The pectoralis major muscle has overcome many of the complications of augmentation mammoplasty after subcutaneous mastectomy. It places the implant deep to prevent skin slough and irregularities in skin surface contour. The flap eliminates abnormal implant posture when the pectoralis major is contracted. The short (5 to 7 days) staging of the procedure allows sealing of the pocket from external innoculation of bacteria while preventing unretrievable skin and nipple shrinkage.
Compared to that of genetically-related normal chickens, pectoralis muscle from the dystrophic chicken contained increased calmodulin measured by radioimmunoassay. Determined by the dot blot procedure, expression of the calmodulin gene was enhanced in muscle from affected animals. The bioactivity of the gene product was normal. Together with previous studies reporting increased cell Ca2+ content in dystrophic muscle, the current findings of increased sarcoplasmic calmodulin suggest the latter is a cellular response to defective Ca2+ transport at the level of cell efflux or intracellular organelle (sarcoplasmic reticulum) uptake.
Electron micrographs of longitudinal ultrathin cryo-sections and plastic sections of chicken pectoralis muscle together with their average images have been used to study in detail the axial structure of the M-band. It was found that M-band structure could vary markedly in different fibres, even within the white part of the muscle. Strong M-band density ("M-bridges") could be seen at M4 and M4' in all fibres. On the other hand the density at M1 or M6 could vary systematically. Some fibres (probably fast) had M1 strong, M6 weak (a "3-line" M-band), and the Z-band was narrow. Other fibres, especially (but not exclusively) in the red part of the muscle and probably slow, had M6 strong, M1 weak (a "4-line" M-band), and the Z-band was broad. However, the majority of fibres ranged in structure between those two extremes and had a more or less "5-line" M-band with M1 and M6 both strong and a Z-band of intermediate width. Since they were such a constant feature, the M4 lines may be the sites of the primarily structural component of the M-band, whereas the different proteins at M1 and M6 may vary in quantity according to the physiological needs of the fibre. Finally, detailed analysis sometimes revealed substructure within the strong M-bridge lines. This substructure may represent additional unknown M-band proteins or may be an indication of the shape of single proteins at these positions.
The expression of myosin heavy chain (MHC) and C-protein isoforms has been examined immunocytochemically in regenerating skeletal muscles of adult chickens. Two, five, and eight days after focal freeze injury to the anterior latissimus dorsi (ALD) and posterior latissimus dorsi (PLD) muscles, cryostat sections of injured and control tissues were reacted with a series of monoclonal antibodies previously shown to specifically bind MHC or C-protein isoforms in adult or embryonic muscles. We observed that during the course of regeneration in each of these muscles there was a reproducible sequence of antigenic changes consistent with differential isoform expression for these two proteins. These isoform switches appear to be tissue specific; i.e., the isoforms of MHC and C-protein which are expressed during the regeneration of a "slow" muscle (ALD) differ from those which are synthesized in a regenerating "fast" muscle (PLD). Evidence has been obtained for the transient expression of a "fast-type" MHC and C-protein during ALD regeneration. Furthermore, during early stages of PLD regeneration this muscle contains MHCs which antigenically resemble those found in the pectoralis muscle at embryonic and early posthatch stages of development. Both regenerating muscles express an isoform of C-protein which appears immunochemically identical to that normally expressed in embryonic and adult cardiac muscle. These results support the concept that isoform transitions in regenerating skeletal muscles qualitatively resemble those found in developing muscles but differences may exist in temporal and tissue-specific patterns of gene expression.
Textured breast implants are difficult to introduce through a small incision. We have developed two new retractors and a new positioning regimen that enables us to use the transaxillary subglandular or subpectoral approach for breast augmentation. These retractors enable us to bluntly dissect the plane beneath the gland or the pectoralis muscle and then adduct the arm so that the relaxed pectoralis or subglandular space can be retracted to allow atmospheric pressure, gravity, and the surgeon's finger to work in unison.
Body weight and carcass component weights of turkeys from a growth-selected line (F), a randombred control population (RBC2), and a commercial sire line (C) were compared at hatch, 4, 8, 12, and 16 wk of age. At hatch there were no significant differences in BW between the F and RBC2 lines, but the C line poults weighed significantly less than the F line poults. Total Pectoralis muscle weight of the F line was larger than for Lines C and RBC2 at hatch, but there were no line differences in drum weight or length. The F line was still heavier than the other lines at 4, 8, and 12 wk, but the absolute and relative weights of the Pectoralis major (P. major) muscle were larger in the C line than the other lines at all ages. Selection for BW increased the weight of the P. major in the F line compared with the RBC2, but differences in the relative weight of the muscle were not consistent. The large line differences for the absolute and relative weight of the P. major were not observed for the Pectoralis minor. At all ages, the lengths of the tibia and femur were greater in the F line than the other lines. At 4 and 8 wk, bone length in the C line was greater than the RBC2, but at 12 and 16 wk there were no significant differences between these lines. The fast-growing F and C lines had more abdominal fat than the RBC2 at 16 wk of age.
We found that beta-actinin isoforms are present in various types of tissues in adult chicken by using immunoblotting after two dimensional gel electrophoresis; for this purpose, an antibody was raised against beta-actinin purified from adult chicken breast muscle (pectoralis major). One of the beta-actinin subunits, beta I, was present in all tissues we examined, i.e. skeletal (pectoralis major, semitendinosus, and anterior latissimus dorsi), cardiac, and smooth (gizzard) muscles, non-muscle (brain, liver, and kidney) tissues and blood, whereas another subunit, beta II, was present only in muscle tissues. A new subunit (designated beta III) that was found in the embryonic stages of skeletal muscle (Asami, Funatsu & Ishiwata (1988) J. Biochem. 103, 72-75) was present instead of beta II in non-muscle tissues and blood. In cardiac and smooth muscles, beta III coexisted with beta I and beta II. The antibody of beta-actinin did not cross-react to cytoplasmic beta-actinin (molecular weight, 80,000 daltons) found in kidney. It was suggested that the combination of beta I and beta III present in non-muscle tissues and blood is identical to the barbed end capping protein isolated from brain by Killiman and Isenberg (EMBO J. 1, 889-894 (1982)). It is likely that beta-actinin forms a genetic family whose constituents have an ability to cap either the pointed or barbed end of actin filaments.
Magnetic resonance (MR) images of three major flight muscles of chicks were obtained with surface coils using a 0.3 Tesla whole body imaging system (FONAR Beta 3000). The two fast muscles, pectoralis major (PM) and posterior latissimus dorsi (PLD), and a slow muscle, anterior latissimus dorsi (ALD), were identified in the axial, coronal, and sagittal images. The signal intensity (SI) of each muscle was electronically measured and its ratio to the background noise (S/N) was determined. Although visually the three muscles showed intermediate SI, the slow and fast muscles could be differentiated on the basis of their S/N values. These values were invariably higher in the slow muscles than in the fast muscles. To understand these differences, the muscles were excised and their mono- and multiexponential MR relaxation times (T1 and T2) were determined at 30 MHz. Multiexponential analysis enhanced the differences between the muscle types. With the sole exception of short T2, all relaxation components of the slow muscles were significantly longer than those of the fast muscles. These results suggest that elevation in the S/N, T1 and T2 values of muscles may not necessarily indicate a pathologic event, but may reflect the preponderance of slow fibers.
Regulation of DNA accumulation may be a particularly important aspect of the regulation of skeletal muscle growth. Since thyroid hormones influence the growth of chicken skeletal muscle, including DNA accumulation, we ascertained whether triiodothyronine (T3) affects the accumulation of nuclei within muscle fibers and 3H-thymidine uptake into nuclei within the basal lamina and muscle total DNA. The number of nuclei and the diameter of pectoralis muscle fiber segments freed of adhering connective tissue were reduced markedly in cockerels treated with propylthiouracil (PTU) during the first month after hatching. T3 replacement for 1 week increased the number of nuclei per unit length of isolated fiber section by as much as 54%, compared to the value for birds receiving PTU alone, without affecting fiber diameter. There was also a 24% increase in the number of nuclei beneath the basal lamina of fiber cross sections near the origin of anterior latissimus dorsi (ALD) muscles within 48 hr after initiating T3 replacement in 25-day-old, PTU-treated cockerels. The incorporation of 3H-thymidine into nuclei beneath the basal lamina of ALD fiber cross sections was increased approximately two-fold at 24 hr after administering T3 to 8-day-old thyroidectomized (Tx) cockerels. Thymidine (-3H) incorporation into total DNA of ALD muscles incubated in vitro for 1 hr was also markedly enhanced as early as 6-12 hour after T3 administration to Tx chicks during the first week after hatching. Data from this study suggest that T3 enhances DNA replication and the accumulation of nuclei within the basal lamina of muscle fibers of thyroid-deprived chicks.(ABSTRACT TRUNCATED AT 250 WORDS)
Developmental changes in the phospholipid, cholesterol, and fatty acid composition of chicken pectoralis muscle cells were analyzed during development in vivo and in tissue culture. The phospholipid composition of muscle cells showed only minor changes during in vivo or in vitro development but there were significant alterations in fatty acid composition. During in vivo development between the 12th and 22nd days the concentration of palmitate and arachidonate decreased with increase in linoleate. In cultured muscle cells the fatty acid composition changes with surprising plasticity depending on the fatty acid supply. Compensatory changes were observed in the chain length and unsaturation of several fatty acids, aimed presumably at maintaining the physical properties of the lipid phase relatively constant.
2 cases of the defect of pectoralis major muscle observed in male cadavers allocated for routine dissection were investigated anatomically, especially on the nerve supply for the defected muscles. In both cases, one on the left and the other on the right side, pectoralis major muscle was defected, the clavicular portion and a small part of sternocostal portion only persisting. Meanwhile, the ipsilateral pectoralis minor muscle was defected in the first case to be a string-like muscle band and was missing in the second case substituted by a membrane which seemed not to be the degenerated same muscle. Both the lateral and medial pectoral nerves supplied the pectoral muscles in the first case. One of rami of the medial pectoral nerve was distributed unusually to the most lateral part of the persisted sternocostal portion. Only the lateral pectoral nerve existed in the second case. In both cases nerves derived from 2 caudal segments, C8 and Th1, were lacking or poor. However, it was suggested that the defect of the muscles was not due to the nonparticipation of these nerves but due to the failure of caudal growth of the pectoral premuscle mass in a five-week embryo (Lewis 1901).
A series of 10 pectoralis minor vascularized muscle transfers to reanimate the face in unilateral facial palsy are presented. The procedure is carried out in two stages. The first stage constitutes a nerve graft from the functional contralateral facial nerve to the preauricular region of the paralyzed side. Six months later, the pectoralis minor is transferred to the denervated side of the face with restoration of its neurovascular pedicle. The muscle is well suited to its new position with respect to length and bulk, as well as its fanlike shape. The diameter of its vascular pedicle is comparable with the facial vessels. The results demonstrate function in 8 of the 10 grafts, the two failures relating to early vascular thrombosis rather than an inability to reinnervate the muscle grafts.
Gliding flight is a postural activity which requires the wings to be held in a horizontal position to support the weight of the body. Postural behaviors typically utilize isometric contractions in which no change in length takes place. Due to longer actin-myosin interactions, slow contracting muscle fibers represent an economical means for this type of contraction. In specialized soaring birds, such as vultures and pelicans, a deep layer of the pectoralis muscle, composed entirely of slow fibers, is believed to perform this function. Muscles involved in gliding posture were examined in California gulls (Larus californicus) and tested for the presence of slow fibers using myosin ATPase histochemistry and antibodies. Surprisingly small numbers of slow fibers were found in the M. extensor metacarpi radialis, M. coracobrachialis cranialis, and M. coracobrachialis caudalis, which function in wrist extension, wing protraction, and body support, respectively. The low number of slow fibers in these muscles and the absence of slow fibers in muscles associated with wing extension and primary body support suggest that gulls do not require slow fibers for their postural behaviors. Gulls also lack the deep belly to the pectoralis found in other gliding birds. Since bird muscle is highly oxidative, we hypothesize that fast muscle fibers may function to maintain wing position during gliding flight in California gulls.