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A novel cadaveric model for anterior-inferior shoulder dislocation using forcible apprehension positioning.

A novel cadaveric model for anterior-inferior shoulder dislocation using forcible apprehension positioning is presented. This model simulates an in vivo mechanism and yields capsulolabral lesions. The scapulae of 14 cadaveric entire upper limbs (82 +/- 9 years, mean +/- standard deviation) were each rigidly fixed to a custom shoulder-testing device. A pneumatic system was used with pulleys and cables to simulate the rotator cuff and the deltoid muscles (anterior and middle portions). The glenohumeral joint was then positioned in the apprehension position of abduction, external rotation, and horizontal abduction. A 6-degree-of-freedom load cell (Assurance Technologies, Garner, North Carolina) measured the joint reaction force that was then resolved into three orthogonal components of compression force, anteriorly directed force, and superiorly directed force. With the use of a thrust bearing, the humerus was moved along a rail with a servomotor-controlled system at 50 mm/s that resulted in horizontal abduction. Force that developed passively in the pectoralis major muscle was recorded with an independent uniaxial load cell. Each of the glenohumeral joints dislocated anterior-inferior, six with avulsion of the capsulolabrum from the anterior-inferior glenoid bone and eight with capsulolabral stretching. Pectoralis major muscle force as well as the joint reaction force increased with horizontal abduction until dislocation. At dislocation, the magnitude of the pectoralis major muscle force, 609.6 N +/- 65.2 N was similar to the compression force, 569.6 N +/- 37.8 N. A cadaveric model yielded an anterior dislocation with a mechanism of forcible apprehension positioning when the appropriate shoulder muscles were simulated and a passive pectoralis major muscle was included. Capsulolabral lesions resulted, similar to those observed in vivo.

Aged↗

Effect of exercise on activation of the p38 mitogen-activated protein kinase pathway, c-Jun NH2 terminal kinase, and heat shock protein 27 in equine skeletal muscle.

OBJECTIVE: To investigate the effects of exercise on activation of mitogen-activated protein kinase (MAPK) signaling proteins in horses. ANIMALS: 6 young trained Standardbred geldings. PROCEDURE: Horses performed a 20-minute bout of exercise on a treadmill at 80% of maximal heart rate. Muscle biopsy specimens were obtained from the vastus lateralis and pectoralis descendens muscles before and after exercise. Amount of expression and intracellular location of phosphospecific MAPK pathway intermediates were determined by use of western blotting and immunofluorescence staining. RESULTS: Exercise resulted in a significant increase in phosphorylation of p38 pathway intermediates, c-Jun NH2 terminal kinase (JNK), and heat shock protein 27 (HSP27) in the vastus lateralis muscle, whereas no significant changes were found in phosphorylation of extracellular regulated kinase. In the pectoralis descendens muscle, phosphorylation of p38 and HSP27 was significantly increased after exercise. Immunohistochemical analysis revealed fiber-type- specific locations of phosphorylated JNK in type 2a/b intermediate and 2b fibers and phosphorylated p38 in type 1 fibers. Phosphorylated HSP27 was strongly increased after exercise in type 1 and 2a fibers. CONCLUSIONS AND CLINICAL RELEVANCE: The p38 pathway and JNK are activated in the vastus lateralis muscle after a single 20-minute bout of submaximal exercise in trained horses. Phosphorylation of HSP27 as detected in the study reported here is most likely induced through the p38 signaling pathway.

Animals↗

Coverage of chest wall defect with pectoralis-breast myocutaneous flap: a report of two cases.

Reconstruction of a chest wall defect remains a challenging problem, especially where such defects are radiation related. Two cases of modified breast flaps associated with pectoralis major muscle were performed to cover a huge mediastinal defect, with heart lung exposure and a post-mastectomy radiation-related chest wall defect with partial rib resection. Both modified breast flaps healed uneventfully. No respiratory distress was encountered post-operatively. The breast flap associated with pectoralis major muscle ensured flap reliability and minimized flap complication. It is easy to raise and its size is large enough to cover of large chest wall defect which is radiation related, or those internal mammary arteries and thoracodorsal arteries compromised in previous surgery where the transverse rectus abdominis myocutaneous (TRAM) flap and latissimus dorsi flap become unreliable. In such cases a contralateral modified breast flap associated with pectoralis major muscle is the better choice.

Aged↗

Total mastectomy with axillary dissection. A modified radical mastectomy.

A technic for total mastectomy with complete axillary dissection has been described. The procedure utilizes division of the pectoralis major muscle between its clavicular and sternal portions, perservation of its innervation, and reconstruction after completion of the dissection. The pectoralis minor muscle is resected. This modification facilitates a thorough axillary dissection, particularly at the apex, while preserving the cosmetic and functional benefits of the Patey operation.

Axilla↗

Continuous intraarterial infusion of prostaglandin E1 and heparin to extend and improve the survival of pedicled musculocutaneous flaps through unusual routes: a clinical preliminary report.

Sixteen pedicled musculocutaneous flaps (pectoralis major, 3; latissimus dorsi, 4; and transverse rectus abdominis musculocutaneous [TRAM], 9) received continuous intraarterial infusion of prostaglandin E1 (5 micrograms/k of flap per day) and heparin (100 to 200 U/cannula per day) for 14 days postoperatively to extend the flap or improve survival in a high-risk patient. Therapy was successful in 15 patients. To preserve the main arterial inflow to the flap, the infusion was administered via the lateral thoracic artery in the pectoralis major and a branch to the serratus anterior muscle in latissimus dorsi flaps in retrograde fashion, respectively, and was via both the ipsilateral deep epigastric artery and the contralateral superficial epigastric artery in TRAM flaps. This technique permits the use of a pedicled flap in some patients who would otherwise require a free flap.

Abdominal Muscles↗

Volume density and distribution of mitochondria in harbor seal (Phoca vitulina) skeletal muscle.

Recent studies have shown that harbor seals (Phoca vitulina) have an increased skeletal muscle mitochondrial volume density that may be an adaptation for maintaining aerobic metabolism during diving. However, these studies were based on single samples taken from locomotory muscles. In this study, we took multiple samples from a transverse section of the epaxial (primary locomotory) muscles and single samples from the m. pectoralis (secondary locomotory) muscle of five wild harbor seals. Average mitochondrial volume density of the epaxial muscles was 5.6%, which was 36.6% higher than predicted for a terrestrial mammal of similar mass, and most (82.1%) of the mitochondria were interfibrillar, unlike athletic terrestrial mammals. In the epaxial muscles, the total mitochondrial volume density was significantly greater in samples collected from the deep (6.0%) compared with superficial (5.0%) regions. Volume density of mitochondria in the pectoralis muscle was similar (5.2%) to that of the epaxial muscles. Taken together, these adaptations reduce the intracellular distance between mitochondria and oxymyoglobin and increase the mitochondrial diffusion surface area. This, in combination with elevated myoglobin concentrations, potentially increases the rate of oxygen diffusion into mitochondria and prevents diffusion limitation so that aerobic metabolism can be maintained under low oxygen partial pressure that develops during diving.

Aerobiosis↗

The alternative supply of the pectoralis major flap based medially in cases with previous surgical use of the internal thoracic artery: an anatomical study.

In the present study we analyzed the anatomical basis for the use of the pectoralis major muscle based on alternative pedicles in order to evaluate its clinical applications in cases of potential lesion of the internal thoracic artery. The patterns of blood supply depending on the internal thoracic artery, previously dissected for coronary by-pass surgery, were studied in both sides of five embalmed cadavers and five anterior thoracic walls taken from autopsies. The secondary vascular pedicles depending on the internal thoracic artery for the pectoralis major muscle were dissected and injected with physiological saline stained solution in the embalmed cadavers. Moreover, studies of intravascular injection by means of radio-opaque contrast and physiological saline stained solution were carried out in the anterior thoracic walls obtained from clinical autopsies. The results showed that complete injection of the pectoralis major muscle was achieved depending exclusively on the two proximal perforating branches of the two first intercostal spaces, which represented the vascular pedicle for medial transposition of the pectoralis major flap, in cases with previous dissection of the internal thoracic artery for coronary by-pass.

Cadaver↗

Influence of ante- and peri-mortem factors on biochemical and physical characteristics of turkey breast muscle.

The course of post-mortem breakdown of glycogen and ATP in turkey pectoralis major muscle was markedly influenced by several ante- and peri-mortem variables. Application of a proper stunning procedure was highly effective in preventing peri- and post-mortem muscle stress reactions. The physiological level of glycogen and ATP was not significantly affected by road transportation covering 260 km. Birds which rested for 24 hrs following transportation had lower glycogen and ATP levels at the moment of slaughter than non-rested birds. According to the changes in the rate and extent of post-mortem biochemical reactions, several meat characteristics such as water-holding capacity, colour, and tenderness were significantly changed. Furthermore, the results also indicate that turkey breast muscle is susceptible to a PSE-like condition as described in pork.

Adenosine Triphosphate↗

Anatomic evaluation of the subcoracoid pectoralis major transfer in human cadavers.

Subcoracoid transfer of the pectoralis major has recently been described as a reconstruction for subscapularis insufficiency. The purpose of this study was to examine the surgically relevant anatomy of this transfer. The importance of understanding this anatomy was recently highlighted to us following our encounter with musculocutaneous neuropraxia in 2 patients after transfer of the entire pectoralis major, one deep to the musculocutaneous nerve. Dissections were performed on 20 fresh, whole human cadavers in which the entire pectoralis major muscle, medial and lateral pectoral nerves, and musculocutaneous nerve were explored and quantified. The relationship between the pectoralis major and the conjoined tendon was studied in situ and after simulated transfers. The medial and lateral pectoral nerves were located far medial to the pectoralis major tendon insertion and appeared to be safe from injury as long as surgical dissection remained lateral to the pectoris minor and less than 8.5 cm from the humeral insertion. Transfer of the pectoralis major superficial to the musculocutaneous nerve created less tension than transfer deep to the musculocutaneous nerve. Because proximal innervation of the coracobrachialis and short head of the biceps is not an uncommon occurrence, a split pectoralis major transfer, release of the proximal musculocutaneous branches, or debulking of the pectoralis major muscle belly may be required in some instances to prevent tension on the nerve. Because of the variability and location of the musculocutaneous nerve, it should always be visualized operatively. Transfer of the pectoralis major tendon lateral to the biceps tendon appeared to best restore the muscle length-tension relationship.

Aged↗

Early post-hatch fasting induces satellite cell self-renewal.

Early post-hatch satellite cell kinetics are an important aspect of muscle development, and understanding the interplay between fasting and muscle development will lead to improvements in muscle mass following an illness, and optimal meat production. The objective of this experiment was to test the influence of immediate post-hatch fasting on satellite cells in the poult. Male Nicholas poults (Meleagris gallopavo) were placed into two treatments: a fed treatment with immediate access to feed and water upon placement and a fasted treatment without access to feed and water for the first three days post-hatch. 5-bromo-2'-deoxyuridine (BrdU) was injected intra-abdominally in all poults to label mitotically active satellite cells. The pectoralis thoracicus muscle was harvested two hours following the BrdU injection. Immunohistochemistry for BrdU, Pax7, Bcl-2, Pax7 with BrdU, and determining myofiber cross-sectional area along with computer-based image analysis was used to study muscle development. Fed poults had higher body masses throughout the experiment (P< or =0.01), and they had higher pectoralis thoracicus muscle mass (P< or =0.01) at ten days of age than the fasted poults. Fed poults had higher satellite cell mitotic activity at three days and four days of age (P< or =0.01) compared to the fasted poults. However, Pax7 labeling index was higher in the fasted poults (P< or =0.01) at three days, four days, and five days post-hatch than the fed group. Similarly Bcl-2 labeling was higher in the fasted than in the fed group at three days post-hatch. Therefore, fasting depleted proliferating satellite cells indicated by the lower BrdU labeling in the fasted poults compared to the fed poults, and conserved the satellite cell proliferative reserve indicated by the higher level of Pax7 labeling for the fasted poults compared to the fed poults.

Animal Nutritional Physiological Phenomena↗

Randomized clinical trial comparing level II and level III axillary node dissection in addition to mastectomy for breast cancer.

BACKGROUND: In addition to mastectomy, level II and level III axillary node dissection procedures are performed widely in Japan. A randomized clinical trial was performed to determine which procedure was more effective. METHODS: One group of women had resection of the pectoralis minor muscle and dissection of level I, II and III axillary lymph nodes (level III dissection). In a second group, the pectoralis minor muscle was left intact and level III axillary lymph node dissection was not performed (level II dissection). A total of 1209 women with stage II breast cancer were enrolled in the study and randomly assigned to one of the two groups. RESULTS: The 10-year cumulative survival rate was 86.6 per cent after level II and 85.7 per cent after level III axillary dissection (hazard ratio (HR) 1.02; P = 0.931, log rank test). The 10-year disease-free survival rate was 73.3 and 77.8 per cent respectively (HR 0.94, P = 0.666). Overall survival and disease-free survival rates in the two groups were similar after both procedures. The duration of surgery was significantly shorter (P < 0.001) and blood loss was significantly less (P = 0.001) after level II dissection. In a survey of patients' symptoms on follow-up, no significant differences were found between the two procedures. CONCLUSION: The addition of pectoralis minor muscle resection and level III axillary lymph node dissection to mastectomy for stage II breast cancer did not improve overall or disease-free survival rates.

Adult↗

Fatty acid binding protein in heart and skeletal muscles of the migratory barnacle goose throughout development.

The long-distance migratory flights of birds are predominantly fueled by the oxidation of fatty acids, which are sourced primarily from extracellular adipose stores. These fatty acids have to be transported, via the circulatory system, to the mitochondria of the active muscles. An important facilitator of fatty acid transport within the cytoplasm of muscle cells is fatty acid binding protein (FABP), which serves as an intracellular carrier of long-chain fatty acids. In mammals, the muscular FABP content is related to the fatty acid oxidation capacity of the tissue. The aim of this study was to measure FABP in samples taken from the cardiac, pectoralis, and semimembranosus muscles of a long-distance avian migrant, the barnacle goose (Branta leucopsis), at various stages of development. Western blot analysis identified a single goose muscle protein of 15 kDa that was able to bind fatty acids and showed a 66% cross-reactivity with antibodies against human heart-type FABP. Captive goslings showed no significant changes in FABP content of either the heart (62.6 +/- 10.6 microgram/g wet wt) or the semimembranosus muscle (8.4 +/- 1.9 microgram/g wet wt) during development. However, in both peripheral and deep sites within the pectoralis muscle, FABP content of samples taken from captive goslings were approximately 10-fold higher throughout development and reached values of 30-40 microgram/g wet wt in fledging goslings at 7 wk of age. A further twofold higher value was seen in wild but not in captive goslings immediately before migration (12 wk of age). Similarly, FABP content was significantly higher in pectoralis samples taken from wild adults (94.3 +/- 3.6 microgram/g wet wt) compared with those from captive adults (60.5 +/- 3.6 micro/g wet wt). These results suggest that the experience of flight activity may be of critical importance in achieving maximal expression of FABP in the pectoralis muscles of postfledging and mature geese immediately before migration.

Aging↗

Electromyographic analysis of the pectoralis major and deltoideus anterior muscles in horizontal "flyer" exercises with loads.

The effective activity of the pectoralis major and deltoideus anterior muscles in horizontal "flyer" exercises with external loads of 25, 50, 75 and 100% of the maximum load was studied in 11 male volunteers. The electromyographic analysis was done by using MEDI-TRACE-200 surface electrodes connected to a biological signal acquisition mode coupled to a PC/AT computer. The electromyographic signals were processed and the values obtained were normalized through maximum voluntary isometric contraction. It was statistically observed that in all types and loads of this exercise, the muscles presented significant differences in the concentric and eccentric phases. In the concentric phase, when different loads were compared, the muscles were more active with 75 and 100% of the maximum load, while in the eccentric phase, higher activity was observed with 100% of the maximum load. By analyzing each load effect in the concentric phase, it was verified that the muscles on the left side were more active than those on the right side with 25, 75 and 100% of the maximum load.

Adolescent↗

Treatment of the chronically infected median sternotomy wound with muscle flaps.

While infection and dehiscence of the median sternotomy wound is a serious complication, débridement, sternal rewiring and wound irrigation will often result in wound healing. However, if these measures fail, radical débridement of all infected tissue and immediate reconstruction with muscle flaps is required and will give excellent results. The pectoralis major muscle based on the thoracoacromial artery is most satisfactory for this reconstruction. The rectus abdominis muscle, while also used, is not as effective because of variations in its proximal blood supply. The author describes 10 patients with chronically infected median sternotomy wounds, seen at St. Michael's Hospital in Toronto, in whom use of these techniques led to a rapid recovery with few complications.

Aged↗

Electromyographic validation of the pectoralis major and deltoideus anterior muscles in inverted "flying" exercises with loads.

Inverted 'flying" exercise with external loads of 25, 50, 75 and 100% of each individual maximum load in the pectoralis major and deltoideus anterior muscles was electromyographically analyzed in eleven male volunteers, using surface electrodes MEDI-TRACE-200 connected to a biological signals acquisition module coupled to a PC/AT computer. Electromyographic signals were processed and the effective values obtained were standardized through maximum voluntary isometric contraction. When the concentric phase of each muscle with the same load was statistically compared with the eccentric phase, it was observed that for all loads all the muscles presented significant electromyographic difference, and that the concentric phase was always higher. By analyzing the different loads for each muscle, it was noticed that in the concentric phase all the muscles presented significant electromyographic activity, being it higher with maximum load. When the effect of each load on different muscle in the concentric and eccentric phases was analyzed, the muscles presented a distinct activity profile.

Adolescent↗