Histo-enzymological evidence for the aneuronal ontogenesis of the pectoralis major muscle of bat and sparrow into atypical "red" muscle.
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More than 200 patients with sternal wound infections have been treated in the Plastic Surgery Department of our Medical Center over the years 1984-1993. Most of these were referrals from other hospitals. In recent years, the cases have become more severe, partially due to the fact that cardiac surgeons tend to operate older and sicker patients more readily than they previously did. 80% of these were post coronary bypass surgery, and the others heart and heart-lung transplants, repair of congenital heart anomalies, valve replacements etc. Several of the cases were cardiac surgery re-do's. Risk factors for developing this complication, such as diabetes, obesity, technical errors of sternal incision, prolonged intubation, the use of aortic balloon, etc. will be discussed. Many of our earlier patients had chronic fistulae following conservative therapy with old treatment modalities. In recent years, patients are usually referred at the acute stage. Most patients undergo removal of sternum and ribs. Previously, reconstruction included mainly transfer of the rectus ahdominis muscle, whereas lately the pectoralis muscles is utilized. Omentum was used in only one case. The importance of pre-operative imaging procedures has been thoroughly studied in our series. Especially important is the definition of the extent of the infection, and localization of foreign bodies causing chronic infections, such as suture material, epicardial electrodes etc. A change in infectants has also been noticed. In the first half of the study period, Pseudomonas aeruginosa comprised at least 40%.(ABSTRACT TRUNCATED AT 250 WORDS)
The purpose of this study was to characterize the influence of temperature on muscle shortening and extensibility in broiler breast muscle (Pectoralis major). The extent of prerigor muscle shortening has been shown to affect the ultimate tenderness of meat, whereas a decrease in extensibility has traditionally been used to define rigor mortis in muscle. Muscle shortening over time was determined at three incubation temperatures: 0, 23, and 41 C. Shortening was measured on intact and excised muscles, as well as on muscle strips with and without attached weight (200 g). The time a muscle strip needed to reach loss of extensibility was also determined at each of the three incubation temperatures. The intact and excised muscles showed some evidence of both cold and rigor (hot) shortening. No extreme shortening effects were found in the muscle strips incubated with or without attached weight. The use of muscle strips to predict intact muscle or excised whole muscle shortening in a complex muscle such as poultry Pectoralis may be limited. The time required to loss of extensibility of the muscle strips, i.e., rigor completion, was 5.5, 4.5, and 0.8 h at 0, 23, and 41 C, respectively. The results show that cold-induced shortening may contribute to toughening of early deboned broiler breast muscle, but its impact on commercial processing and subsequent meat tenderness does not appear to be consistent.
Pectoralis major muscle and musculocutaneous flaps are the most frequently selected for the ventral chest wall, sternum, and anterior mediastinum because of their proximity, reliability, and versatility. These advantages are derived from consistent anatomic features that allow knowledgeable surgeons to use a variety of flap designs tailored to defect needs. The flaps can be transferred on either thoracoacromial or internal mammary vascular pedicles and can be segmentally split to achieve defect closure while retaining portions of the muscle in situ to preserve donor motor function and surface form. The musculocutaneous paddles can be placed in a variety of locations and extended beyond the muscle borders to meet specific defect needs. This anatomic versatility gives pectoralis major muscle and musculocutaneous flaps a most useful role in the reconstruction of defects of the sternum and anterior mediastinum, defects of the ventral and lateral chest wall, and intrathoracic defects such as empyema cavities and bronchopleural fistula. A detailed knowledge of surgical anatomy is essential for optimal application of these flaps in the full spectrum of clinical needs.
1. Musculo-skeletal development was measured in males and females of two genetic lines of turkey breeding stock: one line had been selected mainly for egg production (E-line) while the other had been selected for meat production as well as egg production (M-line). 2. The M-line had a more rapid growth of body weight and breast muscle weight than the E-line but breast muscle yield (breast muscle weight/body weight) did not differ between lines. 3. From an early age, breast length and keel length were longer in the M-line than in the E-line. 4. In older birds, keel depth was greater in the M-line than in the E-line. 5. No differences between lines were detected for depth of the pectoralis muscle, number of muscle fibres in the depth of the pectoralis, or muscle fibre cross sectional areas.
Light microscopy of the pectoralis muscle of rats on a low protein diet did not show such morphological alterations as atrophy, degeneration, or sarcoplasmic edema, but electron microscopy occasionally demonstrated ultrastructural changes only in the sarcomeres of myofibrils. In the affected sarcomeres, the Z-line was disrupted and often showed a jagged structure. The Z-substance with electron opacity was frequently present flowing along the long axis of myofibrils, here referred to as the streaming of Z-lines. In addition, regular striations formed by the reciprocal arrangement of thick and thin filaments disappeared from the affected sarcomeres, though these filaments were still discernible. Two or more consecutive sarcomeres in a single myofibril were occasionally involved in these changes. A further two or more neighboring sarcomeres at the same level of myofibrils were affected transversely by these structural alterations. On the other hand, the ultrastructure of the intestinal smooth muscle was not affected by protein deficiency. The study suggests that the ultrastructural damage induced by a low protein diet is attributed to the activation of endogenous protease by the excess leaking of Ca2+ into the cytosol as a result of lipid peroxidation of cell membrane by raised free radicals, owing to the depletion of glutathione production by protein deficiency. It also suggests that the smooth muscle cells differ in their susceptibility to protein deficiency from the skeletal muscle cells.
The relationship between the rate of protein synthesis and the level of messenger RNA (mRNA) in the breast muscle (pectoralis major) was studied to examine the mechanisms regulating muscle protein synthesis in chicks under various nutritional conditions. The fractional synthesis rate (FSR) of protein was measured by a large-dose injection of L-[4-3H]phenylalanine. Poly(U)-Sepharose 4B affinity chromatography was used to extract Poly(A)+ RNA as mRNA. The first study examined the effect of dietary protein levels (0-60%) on protein synthesis rate and the contents of mRNA and total RNA. The fractional synthesis rate increased with increasing dietary protein levels from 0 to 20%. When chicks were fed high protein diets (40 and 60% of dietary protein), both the FSR and absolute synthesis rate (ASR) of protein were reduced compared with the 20% protein group. Multiple regression analysis indicated that for graded dietary protein levels below the dietary protein requirement, the response of muscle protein synthesis is largely regulated by variation in the ASR per unit RNA (the efficiency of RNA in synthesizing protein). At dietary protein levels above 20%, synthesis rates are also related to changes in the RNA:mRNA ratio (ribosome number relative to mRNA), the mRNA:DNA ratio (mRNA availability) and the DNA:protein ratio (DNA concentration). When chicks were food deprived for 2 d, FSR was reduced to about half that of well-fed controls. Upon refeeding of these chicks with the control diet, the FSR returned to the normal level within 0.5 h. When food-deprived chicks were refed with protein, carbohydrate or fat alone, the FSR returned to the control level within 0.5 h after consumption of each nutrient. The increase in muscle protein synthesis of unfed chicks following refeeding of various nutrients was explained by an increased ASR per unit RNA. Our results suggest that nutrient intake can change muscle protein synthesis rates in chicks largely by altering the ASR per unit RNA, in some cases associated also with changes in the levels of RNA, mRNA and DNA.
The aim of this experiment was to study the consequences of precise feeding on the myofibre characteristics and metabolic traits of the breast muscle (Pectoralis major, Pm) of Muscovy ducks. Twenty-four samples of breast muscle, without skin or subcutaneous fat, from two groups of ducks, control and overfed respectively, were collected at 14 weeks of age. We assayed different chemical (water content, crude proteins, total lipid ashes, total and thermosoluble collagen), biochemical (activities of the CS, LDH and beta-HAD enzymes), histological (muscle fibre typing and intramuscular adipocyte measurements) and technological (drip and cooking losses, texture) determinations. At the force-feeding period, the overfed ducks weighed 6366 g and the control ducks 4606 g of body weight. In the PM muscle, some modifications of the biochemichal parameters and enzyme activities were observed but neither the shear force nor the histological characteristics of the breast muscle were affected by the fattening treatment. The overfed birds had an increased total lipids content (correlated to an increase in the intramuscular area occupied by the adipocyte) and a different fatty acid profile as the result of a higher energy feed intake. The lipids of the Pm muscle of the overfed ducks contained more C16:0, C16:1n-7 and C18:1n-9, but less C18:0, C18:2n-6 and C20:4n-6 than the control birds. These results show that in response to high energy feeding, the muscle is able to respond quickly on a metabolic basis (by increasing the activities of the oxydative enzymes) without changing its typology or morphology. Additionally, fattening was correlated to a degradation in the technological qualities of the breast muscle, especially an increase in the cooking losses.
C-protein from chicken pectoralis muscle has been purified by sequential DEAE-Sephadex and hydroxyapatite chromatography and examined by transmission electron microscopy after spraying in glycerol onto mica and replicating by rotary shadowing with platinum. The most frequently observed particles were of three forms: rod-shaped, U-shaped and V-shaped. Within a size range of 15-40 nm these three groups accounted for 70% of over 800 particles categorized and measured. The remaining particles could not be classified. Since the relative abundance of each of these three forms was well in excess of any of the contaminating proteins detectable by SDS-polyacrylamide gel electrophoresis, we conclude that these variant forms represent C-protein molecules in differing conformations and/or deformations. Particles were observed which were intermediate between rod-shaped and tightly curved U-shaped forms, and between rod and acutely angled V-shaped forms. These results are compatible with a molecular model of a 32 nm X 3 nm flexible, rod-shaped C-protein monomer similar to one previously proposed from hydrodynamic studies and extend recent observations on the ultrastructure of cardiac C-protein. Infrequently, a discontinuously larger V-shaped form was seen, possibly representing a C-protein dimer.
Turkey meat and processed products are very popular in Portugal. However, no studies have been made to assess turkey meat quality. The main objective of this study was to evaluate the quality of turkey breast meat in a Portuguese slaughterhouse, differentiating it to obtain better industrial management, performance, and consumer contentment. Nine hundred and seventy-seven male turkeys (from 16 to 20 wk old) from different flocks (BUT 9 and BIG 6) were evaluated to assess meat quality. Turkeys were slaughtered on different days, electrically stunned (225 V/3 s), and scalded in a vertical water bath at 81 degrees C/5 min. On the slaughter line, the pH and temperature were measured on the pectoralis muscle 15 min postmortem. The carcasses were fast-cooled in a tunnel (-2 degrees C/2 m.s(-1)/90% RH) for 2 h and kept in a refrigeration chamber (0 degree C/85% RH) until deboning (approximately 24 h postmortem). Color and pH 24 h postmortem (pH(24)) were measured on the pectoralis major muscle after carcass deboning. Pectoralis major muscles were selected according to criteria used by Barbut (1996) and drip loss, cooking loss, and total pigments analysis were performed on 67 different sliced meat samples. Muscles classified by pH decline rate, called rapid glycolytic, did not present final quality characteristics that could relate them with pale, soft, and exudative- (PSE) like meat, because there was no relationship between pH 15 h postmortem and lightness (L*), drip loss, or cooking loss. The differences, founded on physicochemical characteristics within pectoralis major muscles, allowed us to establish a criteria of turkey meat quality for dark and PSE-like meat, with L* < or = 44 and pH(24) > or = 5.8 and L* > or = 50 and pH(24) < 5.8, respectively. Based on criteria, the studied population presented 8.1% of carcasses with PSE-like muscles and 12.1% with dark muscles. The association of pH(24) and L* as criteria classification can be useful to classify turkey meat quality.
Ultrastructural changes and glutathione level were investigated in the pectoralis muscle of rats fed a low-protein diet. Electron microscopy demonstrated the ultrastructural changes of occasional myofibrils affected with protein deficiency that were characterized with the streaming and/or disruption of the Z-line and disintegration of sarcomeric striation. In the affected sarcomeres, sarcomere length was often elongated and fragmented thick filaments were present together with dense amorphous materials flowing from the damaged Z-line. Glutathione level of muscle in the low-protein diet group (5% casein) was reduced to about one-third of that in the control diet group (20% casein). The study suggests that depletion of glutathione by protein malnutrition is responsible for inducing myofibrillar damage through the excess leaking of Ca2+ into the cytosol.
A 22-year-old male college student had a syndactyly between the second and third fingers of his left hand, which was congenitally small in size. His left pectoralis muscles were absent. He first walked at the age of 12 months, but soon developed difficulties in walking due to weakness of the legs. Atrophy and weakness of the legs aggravated gradually. He was diagnosed as having peroneal muscular atrophy and Poland syndrome, an association of which has not been reported before. A small number of similar cases of peroneal muscular atrophy with various skeletal abnormalities in the literature suggest that the association is not incidental, but of clinical significance.
The emergence of avian satellite cells during development has been studied using markers that distinguish adult from fetal cells. Previous studies by us have shown that myogenic cultures from fetal (Embryonic Day 10) and adult 12-16 weeks) chicken pectoralis muscle (PM) each regulate expression of the embryonic isoform of fast myosin heavy chain (MHC) differently. In fetal cultures, embryonic MHC is coexpressed with a ventricular MHC in both myocytes (differentiated myoblasts) and myotubes. In contrast, myocytes and newly formed myotubes in adult cultures express ventricular but not embryonic MHC. In the current study, the appearance of myocytes and myotubes which express ventricular but not embryonic MHC was used to determine when adult myoblasts first emerge during avian development. By examining patterns of MHC expression in mass and clonal cultures prepared from embryonic and posthatch chicken skeletal muscle using double-label immunofluorescence with isoform-specific monoclonal antibodies, we show that a significant number of myocytes and myotubes which stain for ventricular but not embryonic MHC are first seen in cultures derived from PM during fetal development (Embryonic Day 18) and comprise the majority, if not all, of the myoblasts present at hatching and beyond. These results suggest that adult type myoblasts become dominant in late embryogenesis. We also show that satellite cell cultures derived from adult slow muscle give results similar to those of cultures derived from adult fast muscle. Cultures derived from Embryonic Day 10 hindlimb form myocytes and myotubes that coexpress ventricular and embryonic MHCs in a manner similar to cells of the Embryonic Day 10 PM. Thus, adult and fetal expression patterns of ventricular and embryonic MHCs are correlated with developmental age but not muscle fiber type.