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At least 163 records · Page 9Linked to original sources
PubMed1992

Geometry of blood-tissue exchange in bat flight muscle compared with bat hindlimb and rat soleus muscle.

We investigated the relationship between capillary-to-fiber geometry and muscle aerobic capacity by comparing the bat flight muscle (pectoralis muscle), i.e., an ultimate case of extreme O2 demand in a mammalian skeletal muscle, with bat hindlimb and rat soleus muscles. At a given sarcomere length (2.1 microns), fiber cross-sectional area was considerably smaller in bat muscles (pectoralis 318 +/- 10 microns 2, hindlimb 447 +/- 35 microns 2) than in rat soleus muscle (2,027 +/- 125 microns 2). Capillary number per fiber cross-sectional area was much greater in bat pectoralis (6,394 +/- 380/mm2) than in bat hindlimb and rat soleus muscle (2,865 +/- 238 and 1,301 +/- 129/mm2, respectively; all values normalized to 2.1-microns sarcomere length). At the same sarcomere length (2.1 microns), the degree of tortuosity and branching of capillaries were significantly greater in bat pectoralis than in bat hindlimb and rat soleus muscle. In bat flight muscle, capillary length per fiber volume was very high (9,025 +/- 342/mm2). It was 2.2- and 5.4-fold larger than in bat hindlimb and rat soleus, respectively. Mitochondria occupied 35.3 +/- 1.2, 16.5 +/- 1.3, and 6.1 +/- 0.9% of the muscle fiber volume in bat pectoralis, hindlimb, and rat soleus muscles, respectively. There was a strong correlation between capillary length (as well as capillary surface) per fiber volume and mitochondrial volume density in all muscles. Considering capillary supply and mitochondrial volume on an individual fiber basis, we found that 1) the number of capillaries around a fiber was linearly related to mitochondrial volume per micron length of fiber in the muscles but that 2) capillary surface per fiber surface, at given mitochondrial volume per micron length of fiber, was about twice as large in bat pectoralis as in rat soleus muscle, whereas in bat hindlimb it was intermediate between that in bat pectoralis and that in rat soleus muscle. This was due to the differences in fiber size (rat soleus greater than bat muscles) and capillary-to-fiber ratio (bat pectoralis greater than hindlimb) between the muscles. It is notable that in the bat, the substantially greater O2 transfer capacity of the flight muscle compared with hindlimb was achieved by increasing the size of the capillary-to-fiber interface, i.e., capillary-to-fiber surface, via an increase in capillary number rather than by substantially reducing fiber size.

Animals↗
PubMed1998

The effect of insulin-like growth factor-I (IGF-I) on protein turnover in the meat-type chicken (Gallus domesticus).

Insulin-like growth factor-I (IGF-I) effects on chicken growth and development are poorly understood. This study examined the effect of IGF-I on protein synthesis rates in various tissues in the male broiler chicken. At three weeks of age, osmotic minipumps were subcutaneously implanted in the scapular area. Chickens were infused with either chicken IGF-I (450 micrograms/kg BW/day) or saline. After treatment for 5 days, the chickens received a flooding dose of [3H]-phenylalanine, and were sacrificed 20 min later. Wing vein blood samples were taken at 0, 5, 10 and 20 min post-injection. The following tissues were removed and frozen for analysis: pectoralis muscle, gastrocnemius muscle, heart, liver, and small intestine. In vivo total protein synthesis measurements were made using the double-label technique. Contractile protein degradation was evaluated using intracellular free 3-methylhistidine concentrations in skeletal muscle. There were no significant differences in absolute or relative body growth rates over the treatment period. Skeletal muscle (pectoralis and gastrocnemius) weights were significantly decreased with IGF-I treatment, while heart weight was significantly increased. Plasma insulin levels were significantly lower in IGF-treated chickens compared to that in control birds. There was no effect of IGF-I on protein synthesis rates in any of the tissues examined. Intracellular free 3-methylhistidine concentrations were higher in both the gastrocnemius (17%) and pectoralis muscles (25%) of chickens treated with IGF-I. This data demonstrates that IGF-I may have an indirect effect to regulate muscle protein turnover rates.

Animals↗
PubMed1991

Computerized angiographic study of the vascular supply of the pectoralis major muscle.

The pectoralis major muscle or musculocutaneous flap is well suited to repair immediately wide defects following surgical removal of carcinomas or traumas of the cervicofacial and thoracic regions. Microsurgery has recently suggested exciting and successful solutions for the same purposes, but we think it is still important to reassess and perfect the flaps already known in order to achieve a better cost-benefit ratio. We examined the intramuscular vascular anatomy of 22 pectoralis major muscles using an image analyzer and a computerized measuring system to quantify the essential features objectively. The data show the segmentation of the pectoralis major muscle into two subunits, each provided with its own vascular supply. Slight anatomical differences and the presence of a well-developed intramuscular vascular supply makes the pectoralis major muscular and musculocutaneous flap a useful and safe procedure.

Aged↗
PubMed1994

Anosognosia for hemiplegia: an electrophysiologic investigation of the feed-forward hypothesis.

The cause of anosognosia for hemiplegia (AHP) remains unclear. Weakness is detected when there is a mismatch between the expectancy of movement and the sensory perception of movement. The feed-forward hypothesis of AHP posits that there is a failure of detection because there is a loss of motor intention and expectancy of movement. We tested motor intention by measuring the activation of proximal muscles (pectoralis majoris) while subjects squeezed a dynamometer with each hand. We tested a group of normal controls, a group of patients with hemiparesis, a patient with neglect, a patient with resolved AHP, and a patient with persistent AHP. The patient with AHP did not contract either of his pectoralis muscles when asked to squeeze with his contralesional, paretic hand, yet he contracted both of them when squeezing the dynamometer with his ipsilesional hand. Normal controls, hemiparetic controls, and the patient with hemispatial neglect contracted both pectorales when asked to squeeze with each hand. The pattern of activation seen in the patients with persistent AHP and resolved AHP demonstrates a loss of motor intention and lends support to the feed-forward hypothesis of AHP.

Agnosia↗
PubMed1998

Influence of preslaughter stunning on turkey breast muscle quality.

Pectoralis muscle quality was evaluated from 18-wk-old tom turkeys after electrical stun, carbon dioxide stun, or no stun methods were applied. Color was measured on raw muscle and cooked meat using a colorimeter. Muscle pH was measured 15 min post-mortem (initial), 24 h post-mortem (final), and after cooking. The right Pectoralis muscle of each carcass was excised for m-calpain analysis within 4 min post-mortem. After 24 h of storage at 4 C, the left Pectoralis muscle was excised to determine cook loss and shear force measurements. No significant difference was found in initial muscle pH (15 min) from turkeys receiving electrical or carbon dioxide stunning, 6.36+/-0.15 and 6.20+/-0.14, respectively. However, initial muscle pH for birds that were not stunned (5.99+/-0.08) was lower (P < 0.05) than the muscle pH of birds stunned using either of the two stunning methods. Stunning method had no effect on the final muscle pH, raw muscle color, cooked meat pH, cooked meat color, cook loss, or shear force. Cook loss was found to positively correlate with initial muscle lightness (r = 0.53), and cooked meat lightness (r = 0.48), but to negatively correlate with cooked meat yellowness (r = -0.48) and shear strength (r = -0.43). m-Calpain activity declined with the stunning methods in the following order: electrical > carbon dioxide > no stun. In addition, m-calpain activity was found to correlate with initial muscle pH (r = 0.95) and with cooked meat shear force (r = -0.43). The results of this study show that electrical stunning, carbon dioxide stunning, and no stunning methods provide comparable cooked turkey breast meat quality with no consistent differences after aging on the carcass for 24 h.

Abattoirs↗
PubMed1996

Electromyographic validation of basic exercises for physical conditioning programmes. II. Analysis of the deltoid muscle (anterior portion) and pectoralis major muscle (clavicular portion) in rowing exercises with closed grip.

The electromyographic activity of the shoulder muscles deltoid-anterior portion (DA) and pectoralis major-clavicular portion (PMC) was tested on 24 male volunteers using a 2 channel TECA TE4 electromyograph and Hewlett Packard surface electrodes during the execution of three different modalities of rowing exercises with closed grip. All rowing exercises were inefficient to determine action potential levels in the PMC but two of them were extremely efficient to the DA: the upright rowing exercise and the sitting rowing exercise. Some suggestions to the use of the tested exercises are presented by the authors.

Action Potentials↗
PubMed1990

Comparison of microscopic and laser diffraction methods for measuring sarcomere lengths of contracted muscle fibers of chicken pectoralis major muscle.

The objective of the present study was to compare the effectiveness of a microscopy method with a laser diffraction method for measuring sarcomere lengths of chicken pectoralis major (p. major) muscle fibers exhibiting various contraction states. Chicken p. major muscles were excised from the animals at death. Samples of each muscle were treated with pH-buffered (5.0 and 7.5) isoionic CaCl2, KCl, or ethylene glycol bis-(b-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA) solutions in order to produce variability in the degree of fiber contraction. Sarcomere lengths (SL) of the fibers were observed using light microscopy and a laser diffraction method. The methods gave comparable results for sarcomere lengths greater than 1.6 microns. However, for SL less than 1.6 microns, sarcomere contraction was not accurately assessed by the laser diffraction method.

Animals↗
PubMed2003

Electromyographic validation of basic exercises for physical conditioning programmes. IV. Analysis of the deltoid muscle (anterior portion) and pectoralis major muscle (clavicular portion) in frontal-lateral cross, dumbbells exercises.

The electromyographic activity of the shoulder muscles deltoid--anterior portion (DA) and pectoralis major--clavicular portion (PMC) was tested on 24 male volunteers using a 2 channel TECA TE4 electromyograph and Hewlett Packard surface electrodes during the execution of four different modalities of frontal-lateral cross, dumbbells exercises. The results showed that all of the tested exercises developed high levels of action potential for both muscles. So, we justify the indication of all of them for physical fitness programmes for DA and PMC. Some suggestions to the use of the tested exercises are presented.

Action Potentials↗
PubMed1989

Influence of sodium pentobarbital on pH, sarcomere length, and muscle tenderness of broiler Pectoralis major muscle.

Six trials were conducted to determine the effect of sodium pentobarbital (SP) anesthesia on broiler muscle pH, sarcomere length, and Allo-Kramer shear values. Birds were divided into six groups, three of which were anesthetized with SP prior to slaughter. Birds from both the anesthetized and nonanesthetized groups were subjected to one of three processing treatments: 1) muscles hot boned as soon as possible after death and immediately analyzed (HB/0); 2) muscles hot boned and aged 24 h in ice/water slush (HB/24); and 3) muscles left on carcass (conventional process) and aged 24 h in ice/water slush (CP/24) before deboning. The SP/HB/0 group was found to have significantly higher (P less than .05) pH values and longer sarcomere lengths than those of the other five treatment groups. No significant differences were observed for pH among the four 24-h aged groups. Sarcomere lengths were found to be shortest in the SP/HB/24 and HB/24 groups followed by SP/CP/24, HB/0, and CP/24 groups. The CP/24 and SP/CP/24 groups had the lowest shear values, with the HB/0, HB/24, and SP/HB/24 groups exhibiting three-fold higher shear values. These results indicate that SP can delay the effects of ante-mortem stress on early rigor processes; however, no such effects were apparent following 24-h aging.

Animals↗
PubMed1997

Tissue-specific alterations in insulin-like growth factor-I concentrations in response to 3,3',5-triiodo-L-thyronine supplementation in the growth hormone receptor-deficient sex-linked dwarf chicken.

Insulin-like growth factor-I (IGF-I) mediates many of the effects of growth hormone (GH). The regulation of IGF-I, independent of GH, is methodologically difficult to assess in vivo, as hypophysectomy results in derangement of many pituitary hormone axes in addition to GH, and a gene knockout model is not available. The recessive sex-linked dwarfing (SLD) gene (dw) in chickens results in a lack of functional target tissue GH receptors due to a variety of molecular defects, which provides a unique model for evaluating GH-independent regulation of IGF-I. In the present study, the impact of 3,3', 5-triiodo-l-thyronine (T3) on circulating and tissue IGF-I was determined in normal versus SLD birds. Adult, nonovulatory female normal and SLD chickens were restrict-fed 40 g of feed/kg bw/day containing 0, 0.5, or 1.0 ppm T3, resulting in supplementation levels of 0 (control), 20 (low dose), or 40 (high dose) microg T3/kg bw/day for 10 days. Samples of GH target tissues including liver, abdominal fat pad, skeletal muscle (pectoralis major), and spleen were extracted and assayed for IGF-I. Plasma T3, T4, GH, and IGF-I were determined by homologous RIA. Tissue GH binding was determined for hepatic membranes by radioreceptor assay. Under control conditions, dwarf chickens were markedly hypersomatotropic (33.3 +/- 4.1 ng GH/ml plasma; mean +/- SEM) compared to normals (2.4 +/- 3.9 ng/ml), and T3 supplementation reduced this to normal levels. Despite the high circulating level of GH in dwarfs, plasma IGF-I was low compared to normal controls (dwarfs 1.5 +/- .9 ng/ml; normals 5. 3 +/- .9 ng/ml; P = 0.004), but this difference was eliminated with low-dose T3. In this study, tissue IGF-I was undetectable in liver and pectoralis muscle in adults (55 weeks of age) of both genotypes, under all treatments. In contrast, adipose tissue IGF-I was relatively high and did not differ (P = 0.84) between genotypes under control conditions (normals 776.5 +/- 236.7; dwarfs 844.6 +/- 236.7 pg/mg protein), but was increased in normals and decreased in dwarfs, resulting in higher levels (P = 0.02) in the normal (1249.9 +/- 200.0 pg/mg protein) than in the dwarf genotype (558.4 +/- 200.0 pg/mg protein) at the higher level of T3 supplementation. This relationship was somewhat reversed in spleen, where T3 tended to decrease tissue IGF-I concentration in normals and increase it in dwarfs. The low level of plasma IGF-I despite nonmeasureable hepatic IGF-I tissue concentrations suggests that IGF-I synthesis by extrahepatic tissues contributes to the circulating pool of IGF-I. The relatively high control levels of adipose tissue IGF-I in the dwarf genotype further suggest that considerable IGF-I synthesis exists that is GH-independent in this extrahepatic tissue. The presence of GH action, however, may mediate the effects of other hormones that can influence local IGF-I production in this tissue, as reflected by the differential response to T3 supplementation between genotypes. The tissue-specific nature of the effect of T3 on IGF-I production supports an additional point of regulation of hormone action at the target tissue level.

Adipose Tissue↗
PubMed2005

Regulation of JAK2 protein expression by chronic, pulsatile GH administration in vivo: a possible mechanism for ligand enhancement of signal transduction.

Growth hormone (GH) is a key factor controlling postnatal growth and development. Despite growth-promoting effects in mammals, GH is not associated with muscle growth in the chicken. Janus kinase 2 (JAK2) has been identified as the first intracellular step in GH receptor (GHR) signaling in many species, however, there is limited knowledge regarding the GH signaling pathway in the chicken. In this study, GH-responsive, JAK2 immunoreactive proteins were first assessed in an avian hepatoma cell line (LMH). Tyrosine phosphorylation of a 120-122 kDa JAK2 immunoreactive protein was GH dose-dependent. In addition to in vitro studies, the timecourse of JAK2 activation in liver and skeletal muscle (Pectoralis superficialis) in response to a single intravenous (i.v.) injection of chicken GH (cGH), and the effect of chronic exposure to GH in a physiologically relevant pattern on JAK2 protein expression and tyrosine phosphorylation in vivo were assessed. At a dose of GH that was previously demonstrated to elicit a maximal metabolic response (6.25 microg/kg BW), maximum tyrosine phosphorylation of JAK2 appeared at 10 min post-GH administration in the pectoralis muscle, but was not detectable in liver. To assess whether chronic enhancement of GH would alter expression of JAK2, we utilized a dynamic model of pulsatile GH infusion that mimicked the early pattern of circulating GH expressed in younger, rapidly growing birds (high amplitude peaks with an inter-peak interval of 90 min). A 120-122 kDa protein in liver and muscle, and a dominant 130-136 kDa protein in the muscle, that was phosphorylated in response to GH, were specifically recognized by the JAK2 antibody. Chronic, pulsatile infusion of cGH into 8-week-old chickens was associated with increased abundance and tyrosine phosphorylation of JAK2 protein in both liver and muscle (P < 0.05), which were GH dose-dependent, and mirrored previously reported biological responses for the same birds [Vasilatos-Younken, R., Zhou, Y., Wang, X., McMurtry, J.P., Rosebrough, R.W., Decuypere, E., Buys, N., Darras, V.M., Van Der Geyten, S., Tomas, F., 2000. Altered chicken thyroid hormone metabolism with chronic GH enhancement in vivo: Consequences for skeletal muscle growth. Journal of Endocrinology 166, 609-620.]. In summary (1) JAK2 immunoreactive proteins that associate with the GHR and are tyrosine phosphorylated in response to GH were identified in an avian hepatoma cell line and expressed in both GH responsive (liver) and "non-responsive" (skeletal muscle) tissues; (2) tyrosine phosphorylation of JAK2 occurred within minutes of exposure to a single i.v. injection of GH in vivo in muscle but not liver of 8-week-old birds; and 3) there were GH dose-dependent increases in abundance of JAK2 protein and tyrosine phosphorylation in both tissues when chronically exposed to GH in a physiologically relevant pattern, that mirrored dose-dependent biological responses, including alterations in the pathway of thyroid hormone metabolism, previously reported. Enhanced JAK2 suggests one possible mechanism whereby chronic, physiologically appropriate exposure to the ligand enhances GH biological action via increased abundance of a key upstream component of the signal transduction pathway.

Animals↗
PubMed2005

Endoscopic assisted harvest of the pedicled pectoralis major muscle flap.

The Pectoralis Major flap is a reliable and versatile flap for head and neck reconstruction. However, it is associated with donor site scarring on the anterior of the chest wall. Endoscopic assisted harvest of a pedicled pectoralis major muscle flap was performed on three patients for head and neck reconstruction. The average incision length was 4.5 cm, the average time taken to harvest the muscle was 37 min. All patients were discharged from hospital on the 5th to 8th postoperative day and one patient had a seroma. Endoscopic harvest of the pedicled Pectoralis major muscle flap minimises postoperative scarring.

Aged↗
PubMedDate not supplied

Electromyographic validation of basic exercises for physical conditioning programmes. I. Analysis of the deltoid muscle (anterior portion) and pectoralis major muscle (clavicular portion) in rowing exercises with middle grip.

The electromyographic activity of the shoulder muscles Deltoid--anterior portion (DA) and Pectoralis major--clavicular portion (PMC) was tested on 24 male volunteers using a 2 channel TECA TE4 electromyograph and Hewlett Packard surface electrodes during the execution of four different modalities of rowing exercises with middle grip. The results showed that rowing exercises are not appropriate for physical fitness programmes for PMC but some of them are significantly useful for DA. The authors present some suggestions to the use of the tested exercises.

Action Potentials↗
PubMed1987

Ultrastructural and cytological changes in the muscle fibers of the pectoralis of the giant Canada goose (Branta canadensis maxima) in disuse atrophy during molt.

Adult male Branta canadensis maxima were collected from a nonmigratory feral population during their premolt, molt and postmolt phases. Lean dry weight of the pectoralis muscle decreased significantly (p less than or equal to 0.0001) during molt, as a result of disuse atrophy. Histochemical analysis revealed that the region of the pectoralis muscle sampled consisted of Red (fast-twitch oxidative-glycolytic) and White (fast-twitch glycolytic) muscle fiber types, in an approximate ratio of 9 to 1. There was no significant (p = 0.1238) difference in the relative percentages of the two fiber types during the three periods of study. There was, however, a significant decrease in mean cross-sectional area of both Red (p less than or equal to 0.0194) and White (p less than or equal to 0.0001) fibers during molt. Red and White fiber areas were strongly correlated with each other during molt (r2 = 0.76, p = 0.0010) and postmolt (r2 = 0.70, p = 0.0052), but not during premolt (r2 = 0.02, p = 0.7626). The latter finding may be related to fiber-type specific hypertrophy in premolt breeding males. Analysis of ultrastructure revealed that there was a significant (p = 0.0003) decrease in the mean myofibrillar cross-sectional area, and a significant increase in both the density (p = 0.0227) and total number (p = 0.0058) of myofibrils within the muscle fibers of the molting birds. These results indicate that the myofibrils split longitudinally during molt-associated disuse atrophy.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2003

Electromyographic validation of basic exercises for physical conditioning programmes. V. The comparison of the response in the deltoid muscle (anterior portion) and the pectoralis major muscle (clavicular portion) determined by the frontal-lateral cross, dumbbells and the rowing exercises.

The action potential level for shoulder muscles deltoid-anterior portion (DA) and pectoralis major-clavicular portion (PMC) determined by four different modalities of execution of rowing exercises, each one with two different grips, was recorded. These were compared with the action potential level determined for the same muscles by four different modalities of execution of the frontal-lateral cross, dumbbells exercises. Twenty-four male volunteers were examined using a 2 channel TECA TE4 electromyograph and Hewlett Packard surface electrodes. The statistic analysis showed significant (p < 0.05) superiority for all the frontal-lateral cross, dumbbells exercises in comparison to all rowing exercises for the PMC, for the DA this generalized supremacy was not observed.

Action Potentials↗