Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Muscle development”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,729 records · Page 96Linked to original sources
PubMed2004

Post-natal developmental expression of alphaKAP splice variants in rabbit fast-twitch and slow-twitch skeletal muscle.

AlphaKAP is a non-kinase product of a gene within alpha CaMKII gene, that anchors catalytic subunits to skeletal muscle sarcoplasmic reticulum. alphaKAP gene expresses two distinct mRNA transcripts by alternative splicing in rabbit fast muscle, rather than one, as an apparently fiber-type specific and species-specific property. We report on the expression profile of alphaKAP gene in fast and slow muscles of adult rats and in rabbit post-natal developing muscles, by RT-PCR analysis of muscle RNA, together with Western blot analysis of expressed alphaKAP protein isoforms. We show that alphaKAP isoform predominantly expressed in muscle of newborn rabbits, corresponds to the fast-adult isoform. In fast muscle, the transition from neonatal isoform to the common adult isoform takes place early after birth, and is never complete, unlike in slow muscle. Relevant to these findings, is the observation that neonatal/embryonic alphaKAP mRNA is highly expressed in rat myotubes grown in vitro. Together, our findings suggest that alphaKAP splicing pathways are primarily modulated according to muscle developmental stage.

Alternative Splicing↗
PubMed2002

Differential expression of neural cell adhesion molecule (NCAM) after tenotomy in rabbit skeletal muscle.

Tenotomy is a commonly encountered event in orthopaedic surgery. In 23 rabbit extensor digitorum longus (EDL) muscles, within 24 h after tenotomy, a marked drop in maximum force production occurred. This was not explainable based on architectural changes and histological examination using standard markers for muscle injury, i.e., haematoxylin and eosin morphology, developmental myosin heavy chain (MHC) immunolabeling, and quantitation of muscle fiber type percentage, area and distribution. The expression of neural cell adhesion molecule (NCAM), a glycoprotein expressed during muscle development was measured as a function of time in these muscles. NCAM expression was increased as early as one day after tenotomy with 2.2+/-1.2% of the fibers showing positive expression. This expression level increased significantly to 15.4+/-15.2% after 7 days and then subsided to 13.2+/-10.6% 21 days after tenotomy. Two-way analysis of variance demonstrated a significant effect of time and a significant time x tenotomy method interaction. These results suggest that tenotomy leads to possible changes in muscle-nerve connections and/or excitation-contraction (EC) coupling.

Animals↗
PubMed2001

Slipped and lost extraocular muscles.

A slipped or lost muscle should be considered in the differential diagnosis of a patient presenting with a marked limitation of duction and inability to rotate the eye beyond the midline. Loss of a rectus muscle can occur after strabismus surgery, trauma, paranasal sinus surgery, orbital surgery, or retinal detachment surgery. The extraocular rectus muscle most frequently slipped or lost is the medial rectus muscle. Forced ductions, active force generation, saccadic velocity studies, differential intraocular pressure measurements, and orbital imaging studies may aid in identifying a slipped or lost muscle. However, no single diagnostic test provides absolute reliability for determining a lost muscle. Slipped muscles develop when the muscular capsule is imbricated without including the muscle or muscle tendon during strabismus surgery. When the capsule is reattached to the sclera, the tendon and muscle are then free to slip posteriorally from the site of attachment. Slipped muscles are retrieved by following the thin avascular muscle capsule posteriorally until the muscle is identified. A lost muscle can be found using a traditional conjunctival approach, by an external orbitotomy, or by an endoscopic transnasal approach. Although many diagnostic maneuvers are useful in identifying a lost rectus muscle, the oculocardiac reflex is the most important. Once the lost muscle is identified, the muscle should be imbricated with a nonabsorbable synthetic suture and securely reattached to the globe.

Diagnosis, Differential↗
PubMed2003

Regulation of oxidative phosphorylation in different muscles and various experimental conditions.

It has been shown previously that direct stimulation of oxidative-phosphorylation complexes in parallel with the stimulation of ATP usage is able to explain the stability of intermediate metabolite (ATP/ADP, phosphocreatine/creatine, NADH/NAD+, protonmotive force) concentrations accompanied by a large increase in oxygen consumption and ATP turnover during transition from rest to intensive exercise in skeletal muscle. It has been also postulated that intensification of parallel activation in the ATP supply-demand system is one of the mechanisms of training-induced adaptation of oxidative phosphorylation in skeletal muscle. In the present paper, it is demonstrated, using the computer model of oxidative phosphorylation in intact skeletal muscle developed previously, that the direct activation of oxidative phosphorylation during muscle contraction can account for the following kinetic properties of oxidative phosphorylation in skeletal muscle encountered in different experimental studies: (i) increase in the respiration rate per mg of mitochondrial protein at a given ADP concentration as a result of muscle training and decrease in this parameter in hypothyroidism; (ii) asymmetry (different half-transition time, t(1/2)) in phosphocreatine concentration time course between on-transient (rest-->work transition) and off-transient (recovery after exercise); (iii) overshoot in phosphocreatine concentration during recovery after exercise; (iv) variability in the kinetic properties of oxidative phosphorylation in different kinds of muscle under different experimental conditions. No other postulated mechanism is able to explain all these phenomena at the same time and therefore the present paper strongly supports the idea of the parallel activation of ATP usage and different oxidative-phosphorylation complexes during muscle contraction.

Adenosine Diphosphate↗
PubMed1983

Fetal muscle characteristics in nemaline myopathy.

In addition to the intracytoplasmic rods in approximately 1/4 muscle fibers, there were a large number of fibers with fetal muscle characteristics in a female infant who had severe muscle weakness and hypotonia, and failure to thrive since birth. A histochemical examination disclosed abnormal distribution in muscle fiber types including remarkable type 1 fiber predominance and increased number of type 2 C fibers (11.4%). Scattered throughout were fibers consisting of multiple myocytes enclosed in a single basement membrane, and small-calibered fibers containing abundant intermediate (skeleton) filaments and dispersed microtubules. Both were histologically identical to premature fibers found in the fetal muscle. The existence of an increased number of satellite cells as compared with age-matched controls was also suggestive of delayed or arrested muscle fiber maturation. A certain impaired neural influence upon the developing muscle is probably responsible for producing abnormal fiber type distribution and immature small-calibered fibers which account for small muscle bulk and muscle weakness in nemaline myopathy.

Asphyxia Neonatorum↗
PubMed1998

Gender differences in FFM accumulation and architectural characteristics of muscle.

PURPOSE: The purpose of this study was to gain insight into the skeletal muscle development potential in women and to evaluate the contribution of muscle pennation angle (PANG) and fascicle length to gender differences in muscle size or FFM accumulation. METHODS: Skeletal muscle architectural characteristics and FFM were studied in 29 strength-trained female and 22 age- and height-matched male college athletes. Muscle thickness (MTH) was measured by B-mode ultrasound at 13 anatomical sites. Isolated MTH and PANG of the triceps long head (TL), vastus lateralis (VL), and gastrocnemius medialis (MG) muscles were measured in vivo, and fascicle length was estimated. RESULTS: Six female athletes had more than 60 kg of FFM, with the largest being 82.1 kg. In general, male athletes had a significantly greater FFM and MTH at all sites except for the anterior thigh. Isolated MTH and PANG of the TL, VL, and MG were greater in males. There were no gender differences in limb length or fascicle length of the three isolated muscles. A significant correlation was observed between MTH and PANG for TL (r = 0.84) and MG (r = 0.41), but not for VL. CONCLUSIONS: In contrast to previous estimates, we conclude that the theoretical upper limit of FFM accumulation and FFM-to-height ratio in women is greater than 80 kg and 0.44 kg.cm-1, respectively. Gender differences in PANG appear to be related to differences in muscle size (MTH) and do not appear to contribute independently to the gender difference in FFM.

Adipose Tissue↗
PubMed2002

Sexual dimorphism is associated with decreased expression of processed myostatin in males.

Myostatin inhibits skeletal muscle development. Therefore, we sought to determine whether larger body and muscle mass in male mice was associated with lower mRNA and protein expression of myostatin compared with females. Ten male and ten female mice of the C57 strain were killed at 16-18 wk of age, and their biceps femoris, gastrocnemius, and quadriceps femoris muscles were collected. Body and muscle masses were 40% heavier (P < 0.001) in males than in females. Northern analysis showed no difference in mRNA between males and females. In contrast, Western analysis showed that processed myostatin (26 kDa) was 40-60% lower (P < 0.001) in males compared with females. These data show first that decreased processed myostatin is a posttranscriptional and posttranslational event and, second, that decreased abundance of processed myostatin is associated with increased body mass and skeletal muscle mass in male compared with female mice.

Age Factors↗
PubMedDate not supplied

Electromyographic study of the longissimus dorsi and iliocostalis lumborum muscles during knee flexion and extension on a plain and on a tilt Roman table.

The objective of this paper was to analyse the activity of the longissimus dorsi and the iliocostalis lumborum muscles--components of the erector spinae muscle--in order to determine: their action potentials during the use of a plain and a tilt Roman table; 2) to compare the action potentials of the two muscles; 3) to verify if the action potential of these two muscles remain constant during the arc of movement--knee flexion and extension--divided into angle ranges, and 4) to compare the action potentials of the muscles in movements performed in a free manner and against resistance. Twenty-three young volunteers were studied electromyographically and each muscle received a needle electrode (Mise) and a surface electrode. The results showed that the table model did not determine any difference in the action potential of the muscles and that, on average, the iliocostalis lumborum muscle developed a slightly higher action potential than the longissimus dorsi muscle during the free flexion of knees on the plain table. In more than 70% of the cases, there was no difference between the action potential of the muscles over the various angle ranges of knee flexion and extension. Relatively higher action potentials were recorded during knee flexion and extension against resistance than during the same movements performed in a free manner. This shows that the paravertebral musculature responds better to an overload (8 kg) imposed on the knee flexor group, confirming the stabilizing role of the longissimus dorsi and iliocostalis lumborum muscles during knee flexion and extension on a Roman table.

Action Potentials↗
PubMed1967

Tension development by isolated muscle spindles of the cat.

1. Tension developed by mammalian intrafusal muscle fibres stimulated directly with single or repetitive electrical pulses has been determined in sixteen isolated lumbrical muscle spindles of the cat's foot.2. On microscopic observation, contraction to single shocks was observed in ten preparations. In three of these preparations twitch-like records were obtained.3. In the preparations that ;twitched', the tetanic fusion frequency was 10 pulses/sec at 20 degrees C.4. In the ;twitching' intrafusal fibres the magnitude of contraction increased with increase of stimulus strength.5. In one of these spindles, only ;slow' contractions were obtained at low stimulus strengths when it was stimulated repetitively at 100 pulses/sec. With increase in stimulus strength, such ;slow' contractions gave twitch-like responses towards the end of a period of repetitive stimulation.6. Tension changes were recorded from all preparations stimulated repetitively. With supramaximal stimuli, the usual frequency of stimulation at which intrafusal tension was recorded was 10 pulses/sec at 20 degrees C. The magnitude of contraction increased progressively with increase in stimulus frequency.7. Larger intrafusal tensions and faster time courses of contraction were obtained when the electrodes were astride the capsular region than when they were over the inferior extracapsular region.

Journal Article↗
PubMed1999

Synapse formation molecules in muscle and autonomic ganglia: the dual constraint hypothesis.

In 1970 it was thought that if the motor-nerve supply to a muscle was interrupted and then allowed to regenerate into the muscle, motor-synaptic terminals most often formed presynaptic specializations at random positions over the surface of the constituent muscle fibres, so that the original spatial pattern of synapses was not restored. However, in the early 1970s a systematic series of experiments were carried out showing that if injury to muscles was avoided then either reinnervation or cross-reinnervation reconstituted the pattern of synapses on the muscle fibres according to an analysis using the combined techniques of electrophysiology, electronmicroscopy and histology on the muscles. It was thus shown that motor-synaptic terminals are uniquely restored to their original synaptic positions. This led to the concept of the synaptic site, defined as that region on a muscle fibre that contains molecules for triggering synaptic terminal formation. However, nerves in developing muscles were found to form connections at random positions on the surface of the very short muscle cells, indicating that these molecules are not generated by the muscle but imprinted by the nerves themselves; growth in length of the cells on either side of the imprint creates the mature synaptic site in the approximate middle of the muscle fibres. This process is accompanied at first by the differentiation of an excess number of terminals at the synaptic site, and then the elimination of all but one of the terminals. In the succeeding 25 years, identification of the synaptic site molecules has been a major task of molecular neurobiology. This review presents an historical account of the developments this century of the idea that synaptic-site formation molecules exist in muscle. The properties that these molecules must possess if they are to guide the differentiation and elimination of synaptic terminals is considered in the context of a quantitative model of this process termed the dual-constraint hypothesis. It is suggested that the molecules agrin, ARIA, MuSK and S-laminin have suitable properties according to the dual-constraint hypothesis to subserve this purpose. The extent to which there is evidence for similar molecules at neuronal synapses such as those in autonomic ganglia is also considered.

Animals↗
PubMed1981

Histochemical patterns of dehydrogenase activity in the development of free muscle grafts in the rat.

Patterns of activity of six dehydrogenase enzymes were studied histochemically in 42 free muscle grafts in the rat. Within hours, the surviving peripheral muscle fibers can be distinguished from the central ischemic muscle fibers. The surviving muscle fibers retain their characteristic pattern of staining throughout the post-transplantation period. The central ischemic muscle fibers stain abnormally and by five or six days they lose their enzymatic activity. The zone of regeneration, between the surviving and the ischemic muscle fibers, initially shows little dehydrogenase activity, but as the regenerating muscle fibers mature, they develop first a homogeneous staining pattern and, later, differences in staining intensity among different types of muscle fibers.

Animals↗
PubMed2005

The you gene encodes an EGF-CUB protein essential for Hedgehog signaling in zebrafish.

Hedgehog signaling is required for many aspects of development in vertebrates and invertebrates. Misregulation of the Hedgehog pathway causes developmental abnormalities and has been implicated in certain types of cancer. Large-scale genetic screens in zebrafish have identified a group of mutations, termed you-class mutations, that share common defects in somite shape and in most cases disrupt Hedgehog signaling. These mutant embryos exhibit U-shaped somites characteristic of defects in slow muscle development. In addition, Hedgehog pathway mutations disrupt spinal cord patterning. We report the positional cloning of you, one of the original you-class mutations, and show that it is required for Hedgehog signaling in the development of slow muscle and in the specification of ventral fates in the spinal cord. The you gene encodes a novel protein with conserved EGF and CUB domains and a secretory pathway signal sequence. Epistasis experiments support an extracellular role for You upstream of the Hedgehog response mechanism. Analysis of chimeras indicates that you mutant cells can appropriately respond to Hedgehog signaling in a wild-type environment. Additional chimera analysis indicates that wild-type you gene function is not required in axial Hedgehog-producing cells, suggesting that You is essential for transport or stability of Hedgehog signals in the extracellular environment. Our positional cloning and functional studies demonstrate that You is a novel extracellular component of the Hedgehog pathway in vertebrates.

Animals↗
PubMed2004

Muscle satellite cell heterogeneity: in vitro and in vivo evidences for populations that fuse differently.

During development, muscle growth results from the proliferation of satellite cells (SC) and their fusion with fibers. Several studies revealed heterogeneity of SC population notably based on the proliferation rate. Here, we examined the SC characteristics of turkey skeletal muscles in terms of proliferation and more specifically fusion, to define if the ability of these cells to fuse may represent a distinct characteristic between them and could be directly associated with their proliferation properties. Freshly extracted SC were plated in clonal condition and their proliferation rate was assessed 11 days later. To investigate the SC fusion behavior, in vitro and in vivo approaches were developed. Highly and slowly proliferative SC were initially labeled with a nuclear beta-galactosidase (beta-Gal) activity and co-cultured with differentiated primary cultures. After 5 days, distribution of beta-Gal positive (beta-Gal+) nuclei was examined. Also, the two labeled SC types were transplanted into different muscles in autologous model. One week later, number of beta-Gal+ nuclei per fiber and diameter of fibers displaying beta-Gal+ nuclei were determined. In vitro, we showed that SC from turkey skeletal muscle are present as a heterogeneous population in terms of proliferation. Examination of their fusion properties in vitro as well as in vivo revealed that highly proliferative SC exclusively exhibited fusion with differentiated myotubes or myofibers, whereas slowly proliferative SC mainly fused together. Collectively, these data demonstrate for the first time that SC with different proliferation rate also intrinsically differ in their fusion potential, suggesting distinct roles for these sub-populations in muscle growth.

Animals↗
PubMed1988

Development of the esophageal muscles in embryos of the sea urchin Strongylocentrotus purpuratus.

Development of the esophageal muscles in embryonic sea urchins is described using light- and electron microscopy. The muscles develop from processes of about 14 cells of the coelomic epithelium that become immunoreactive to anti-actin at about 60 h (12-14 degrees C). Initially, each myoblast extends a single process with numerous fine filopodia around the esophagus. By 72 h the processes have reached the midline and fused with those from cells of the contralateral coelomic sac. Myoblasts begin to migrate out of the coelomic epithelium between 72 and 84 h. By 72 h the processes stain with the F-actin specific probe NBD-phallacidin. The contractile apparatus is not evident in transmission electron-microscopic preparations of embryos at 70 h, but by 84 h the contractile apparatus is present and the muscle cells are capable of contraction. Because the myoblasts migrate free of the coelomic epithelium and are situated on the blastocoelar side of the basal lamina, it is suggested that that they should be considered as a class of mesenchymal cells.

Animals↗
PubMed1999

Inhibition of in vitro enteric neuronal development by endothelin-3: mediation by endothelin B receptors.

The terminal colon is aganglionic in mice lacking endothelin-3 or its receptor, endothelin B. To analyze the effects of endothelin-3/endothelin B on the differentiation of enteric neurons, E11-13 mouse gut was dissociated, and positive and negative immunoselection with antibodies to p75(NTR )were used to isolate neural crest- and non-crest-derived cells. mRNA encoding endothelin B was present in both the crest-and non-crest-derived cells, but that encoding preproendothelin-3 was detected only in the non-crest-derived population. The crest- and non-crest-derived cells were exposed in vitro to endothelin-3, IRL 1620 (an endothelin B agonist), and/or BQ 788 (an endothelin B antagonist). Neurons and glia developed only in cultures of crest-derived cells, and did so even when endothelin-3 was absent and BQ 788 was present. Endothelin-3 inhibited neuronal development, an effect that was mimicked by IRL 1620 and blocked by BQ 788. Endothelin-3 failed to stimulate the incorporation of [3H]thymidine or bromodeoxyuridine. Smooth muscle development in non-crest-derived cell cultures was promoted by endothelin-3 and inhibited by BQ 788. In contrast, transcription of laminin alpha1, a smooth muscle-derived promoter of neuronal development, was inhibited by endothelin-3, but promoted by BQ 788. Neurons did not develop in explants of the terminal bowel of E12 ls/ls (endothelin-3-deficient) mice, but could be induced to do so by endothelin-3 if a source of neural precursors was present. We suggest that endothelin-3/endothelin B normally prevents the premature differentiation of crest-derived precursors migrating to and within the fetal bowel, enabling the precursor population to persist long enough to finish colonizing the bowel.

Animals↗
PubMed1996

Functional redundancy of the muscle-specific transcription factors Myf5 and myogenin.

The myogenic basic helix-loop-helix transcription factors, Myf5, MyoD, myogenin and MRF4, play key roles in skeletal muscle development. All of them induce myogenic differentiation in cultured non-muscle cells, suggesting that they might be functionally redundant. But the genes are expressed at different times during embryogenesis and mice carrying a mutation in any of the genes have different phenotypes. A rib cage defect was observed in Myf5-deficient mice, which die perinatally. We investigated whether the rib cage defect was due to the failure of the early activation of the gene or to the unique interactions of Myf5 with specific downstream targets. For this we inserted a myogenin complementary DNA into the Myf5 locus by homologous recombination which simultaneously disrupted Myf5 function. We report here that mice homozygous for this myogenin gene knock-in (ki) developed a normal rib cage and were viable, therefore demonstrating functional redundancy of Myf5 and myogenin for rib formation.

Animals↗
PubMed2005

Thyroid hormone controls multiple independent programs required for limb development in Xenopus laevis metamorphosis.

Thyroid hormone (TH) is required for limb development in Xenopus laevis. Specific cell types in the growing limb were targeted for expression of a dominant negative form of the TH receptor by sperm-mediated transgenesis. Limb muscle development, the innervation of muscle from the spinal cord, and cartilage growth can be inhibited without affecting patterning of the limb or differentiation of other cell types. Remodeling of the skin occurs late in metamorphosis after the limb has formed. The coordination of these independent programs is affected in part by the control that TH exerts over DNA replication in all cell types of the limb.

Animals↗
PubMed1996

A molecular mechanism for synapse elimination: novel inhibition of locally generated thrombin delays synapse loss in neonatal mouse muscle.

Activity-dependent, polyneuronal synapse elimination (ADPSE) is a programmed, regressive event in the development of the nervous system and readily studied at the neuromuscular junction, where it is complete 15-20 days after birth. Local excess, or imbalanced, protease activity is one of several possible underlying mechanisms. In this regard, thrombin mediates activity-dependent synapse loss in an in vitro model of ADPSE. To test the involvement of thrombin in vivo, we locally applied the leech thrombin-specific inhibitor, hirudin. We monitored neuromuscular behavior, correlated with acetylcholinesterase and silver nitrate histochemistry at endplates, for changes in the timecourse of in vivo synapse elimination and assayed both thrombin activity and prothrombin expression in developing muscle. Hirudin retarded elimination, without altering motor performance, uniquely at Postnatal Day 5 (P5) and maximally at P9. Reverse transcription-polymerase chain reaction (PCR) showed that neonatal muscle was a source of local prothrombin, with peak expression during the first week after birth. A specific chromogenic assay revealed that local thrombin, activated from muscle-derived prothrombin, peaked during maximal synapse remodeling.

Animals↗