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PubMed2004

Composition, color, and texture of Thai indigenous and broiler chicken muscles.

Chemical compositions and physical properties of mixed-sex Thai indigenous (Gallus domesticus) and broiler (commercial breed, CP707) chicken biceps femoris and pectoralis muscles were determined. Indigenous chicken muscles contained higher protein contents but lower fat and ash contents compared to broiler muscles (P < 0.001). The amino acid profile of the indigenous chicken muscles was similar to that of the broiler muscles except they were slightly richer in glutamic acid (P < 0.05). The indigenous chicken muscles contained more saturated and less polyunsaturated fatty acids than the broiler muscles. There were no differences in the monounsaturated fatty acid contents between the breeds. The total collagen contents of indigenous pectoralis and biceps femoris muscles were 5.09 and 12.85 mg/g, respectively, which were higher than those found in broiler pectoralis (3.86 mg/g) and biceps femoris muscles (8.70 mg/g) (P < 0.001). Soluble collagen contents were lower for indigenous pectoralis and biceps femoris muscles, 22.16 vs. 31.38% and 26.06 vs. 33.87%, respectively. The CIE system values of lightness (L*), redness (a*), and yellowness (b*) of indigenous chicken muscles were higher than those of broiler muscles. The shear values of indigenous chicken muscles either raw or cooked were higher than those of broiler muscles (P < 0.05). After cooking, the shear values decreased for broiler biceps femoris and pectoralis muscles (P < 0.05), whereas no change was observed for indigenous chicken biceps femoris muscle (P > 0.05). Shear values increased for indigenous chicken pectoralis muscle (P < 0.05).

Amino Acids↗
PubMed1979

Microsomal T system: a stereological analysis of purified microsomes derived from normal and dystrophic skeletal muscle.

Heterogeneous populations of microsomes obtained from normal and dystrophic chicken pectoralis muscle were separated into two subfractions by an iterative loading technique. The buoyant density of the sarcoplasmic reticulum (SR) microsomes was increased after loading them with calcium oxalate. Several incubations in the transport medium were necessary to load all of the SR. The fraction that did not form a pellet contained microsomes which displayed freeze-fracture faces that had a low density of particles. A stereological analysis was used on membrane fracture faces of intact muscle to generate reference particle density distributions, which were compared with the distributions measured on the microsomal fracture faces. The concave microsomal fracture faces of purified microsomes which did not load calcium oxalate had particle distributions nearly identical to the distributions of intact P-face T tubules. The morphological data suggest that this subfraction is microsomal T system. Biochemical measurements show negligible amounts of specific Na+, K+-ATPase activity, suggesting that there was little contamination from the surface membrane in this subfraction. Furthermore, an active Ca2+-ATPase is demonstrated in both normal and dystrophic T-tubular membranes.

Animals↗
PubMed2005

In ovo exposure to monochromatic green light promotes skeletal muscle cell proliferation and affects myofiber growth in posthatch chicks.

Our previous studies demonstrated that illumination of chicken embryos with monochromatic green light results in enhanced body and muscle weight at later posthatch stages. In the present study, we investigated the cellular and molecular basis of this phenomenon. First, we showed that on day 6 posthatch, myofibers were more uniform in the in ovo illuminated group than in the control group incubated in the dark, with respect to the number of myofibers displaying diameter values within the range of the mean value. Second, we tested the hypothesis that in ovo illumination causes an increase in the number of myoblasts; this in turn can promote posthatch muscle growth. Indeed, a significant increase in the number of skeletal muscle cells isolated from pectoralis muscle was observed in the in ovo illuminated group on days 1 and 3 posthatch relative to the control group. This increased cell number was accompanied by higher expression levels of Pax7 and myogenin proteins on posthatch days 1 and 3, respectively. A parallel analysis of proliferating cells in the intact muscle further demonstrated a significant increase in the number of cells positive for proliferating cell nuclear antigen in muscle from the in ovo illuminated group. Third, we demonstrated that the transition from fetal- to adult-type myoblasts, normally occurring in late stages of chicken embryogenesis, is initiated earlier in embryos subjected to in ovo green-light illumination. We suggest that the stimulatory effect of in ovo illumination on posthatch muscle growth is the result of enhanced proliferation and differentiation of adult myoblasts and myofiber synchronization.

Animals↗
PubMed2005

Patterns of strain and activation in the thigh muscles of goats across gaits during level locomotion.

Unlike homologous muscles in many vertebrates, which appear to function similarly during a particular mode of locomotion (e.g. red muscle in swimming fish, pectoralis muscle in flying birds, limb extensors in jumping and swimming frogs), a major knee extensor in mammalian quadrupeds, the vastus lateralis, appears to operate differently in different species studied to date. In rats, the vastus undergoes more stretching early in stance than shortening in later stance. In dogs, the reverse is true; more substantial shortening follows small amounts of initial stretching. And in horses, while the vastus strain trajectory is complex, it is characterized mainly by shortening during stance. In this study, we use sonomicrometry and electromyography to study the vastus lateralis and biceps femoris of goats, with three goals in mind: (1) to see how these muscles work in comparison to homologous muscles studied previously in other taxa; (2) to address how speed and gait impact muscle actions and (3) to test whether fascicles in different parts of the same muscle undergo similar length changes. Results indicate that the biceps femoris undergoes substantial shortening through much of stance, with higher strains in walking and trotting [32-33% resting length (L0)] than galloping (22% L0). These length changes occur with increasing biceps EMG intensities as animals increase speed from walking to galloping. The vastus undergoes a stretch-shorten cycle during stance. Stretching strains are higher during galloping (15% L0) than walking and trotting (9% L0). Shortening strains follow a reverse pattern and are greatest in walking (24% L0), intermediate in trotting (20% L0) and lowest during galloping (17% L0). As a result, the ratio of stretching to shortening increases from below 0.5 in walking and trotting to near 1.0 during galloping. This increasing ratio suggests that the vastus does relatively more positive work than energy absorption at the slower speeds compared with galloping, although an understanding of the timing and magnitude of force production is required to confirm this. Length-change regimes in proximal, middle and distal sites of the vastus are generally comparable, suggesting strain homogeneity through the muscle. When strain rates are compared across taxa, vastus shortening velocities exhibit the scaling pattern predicted by theoretical and empirical work: fascicles shorten relatively faster in smaller animals than larger animals (strain rates near 2 L s-1 have been reported for trotting dogs and were found here for goats, versus 0.6-0.8 L s-1 reported in horses). Interestingly, biceps shortening strain rates are very similar in both goats and rats during walking (1-1.5 L s-1) and trotting (1.5-2.5 L s-1, depending on speed of trot), suggesting that the ratio of in vivo shortening velocities (V) to maximum shortening velocities (Vmax) is smaller in small animals (because of their higher V(max)).

Analysis of Variance↗
PubMed2003

An audit of the incidence of arm lymphoedema after prophylactic level I/II axillary dissection without division of the pectoralis minor muscle.

UNLABELLED: Lymphoedema is reported to occur in approximately one in four women following curative treatment for breast cancer. Reported rates are almost exclusively for level 1,2,3 axillary clearance with few data for the current practice of level 1,2 dissections. Swelling can affect the whole upper limb but frequently will remain restricted to hand, forearm or upper arm. The aims of this study were to determine incidence after level 1,2 dissection, degree and site of swelling and risk factors which might determine such incidences. Results were available on 198 patients. The cumulative prevalence of lymphoedema after level 1,2 dissections was 14% in the arm, 12% in the forearm and 16% in the hand, assuming a circumference difference of more than 5% indicated lymphoedema. Moderate lymphoedema representing more than 10% circumference difference was found in 1% (arm), 3.5% (forearm) and 0.5% in the hand. Risk factors for lymphoedema were experience of the surgeon (upper arm only), dominant limb (forearm only) and right-sided cancer treatment (for hand only). When lymphoedema in any site was considered, right-sided treatment and nodal status were independently significant. CONCLUSIONS: This study demonstrates that lymphoedema is a common complication following level 1,2 dissection. Whole limb volume is often considered the main outcome measure for detecting lymphoedema and determining success of treatment, yet swelling may be restricted to regions of the limb and site specific circumference measurements are therefore recommended. Pre- and postoperative circumference measurements are likely to be the most sensitive way of determining presence of lymphoedema following surgery for breast cancer.

Adult↗