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At least 1,351 records · Page 75Linked to original sources
PubMed2004

[Development of muscle strength in knee, hip and ankle joints after ACL reconstruction].

INTRODUCTION: We searched for answers for following questions: How does the knee muscle strength change in dependence of post OP time after the same ACL-rehabilitation's program? Which changes in muscle strength occur in hip and ankle muscles after ACL? METHODS: In this study 69 patients with ACL-Reconstruction participated, mean 31 years. The Lysholm- and OAK-scores of all were good respectively very good. 28 patients were 3 - 6 months post OP (Gr. I), 20 were 6 - 12 months post OP (Gr. II), 21 was 12 - 24 months post OP (Gr. II). All patients were tested on the isokinetic Cybex 6000, for dynamic concentric strength and endurance. The evaluation parameters chosen were: max.moment at angle speed of 60 degrees /sec and endurance index at 120 degrees /sec, RESULTS: The analysis of the max. moment showed significant (P < 0.05) changes in both knee extension and flexion in all groups, in the hip flexors and extensors in group I, and hip flexors in group II and III. In the ankle joint we only found significant changes in the plantarflexors of group I. Looking at the endurance index we observed that many muscle groups of the injured leg presented higher values, however the difference is only significant in the knee flexors and extensors of group I and in the hip flexors of group III. CONCLUSION: Our study showed strength loss in both knee extensors and knee flexors in all patients who had undergone reconstruction surgery after the same ACL-rehabilitation's program. We can state that there is strength loss in hip and ankle muscles in 3 - 6 months post OP patients. A reduction of muscle strength at the hip flexor from all patients was seen after 12 months post-OP. It is suggested that the strength loss in the hip flexors could be due to bi-articular muscles surrounding the knee.This results has to be consider on the planning of strength training after ACL injuries.

Adult↗
PubMed1982

Further data on the androgenic dependency of the skeletal musculature: the effect of prepubertal castration on the structural development of the skeletal muscles.

The effect of prepubertal castration was investigated in the soleus, semimembranosus and levator ani muscles of rat, using light and electronmicroscopic morphometric methods. After castration the semimembranosus and the levator ani muscles showed significant morphometrical alterations. The weight of the muscles diminished, the diameter of the white fibers decreased. The ultrastructure of these muscles showed a well expressed myofibrillar atrophy. The changes in the semimembranosus muscle were less severe. The slow oxidative soleus muscle did not show any similar alterations. The changes in the levator ani and semimembranosus muscles could be prevented or moderated by testosterone substitution.

Animals↗
PubMed2001

The sarco-endoplasmic reticulum Ca2+ ATPase is required for development and muscle function in Caenorhabditis elegans.

The sarco-endoplasmic reticulum Ca(2+)-transport ATPase (SERCA) loads intracellular releasable Ca(2+) stores by transporting cytosolic Ca(2+) into the endoplasmic (ER) or sarcoplasmic reticulum (SR). We characterized the only SERCA homologue of the nematode Caenorhabditis elegans, which is encoded by the sca-1 gene. The sca-1 transcript is alternatively spliced in a similar mode as the vertebrate SERCA2 transcript, giving rise to two protein variants: CeSERCAa and CeSERCAb. These proteins showed structural and functional conservation to the vertebrate SERCA2a/b proteins. The CeSERCAs were primarily expressed in contractile tissues. Loss of CeSERCA through gene ablation or RNA interference resulted in contractile dysfunctioning and in early larval or embryonic lethality, respectively. Similar defects could be induced pharmacologically using the SERCA-specific inhibitor thapsigargin, which bound CeSERCA at a conserved site. The conservation of SERCA2 homologues in C. elegans will allow genetic and chemical suppressor analyses to identify promising drug targets and lead molecules for treatment of SERCA-related diseases such as heart disease.

Animals↗
PubMedDate not supplied

A conceptual model of factors contributing to the development of muscle dysmorphia.

Muscle dysmorphia is a recently described subcategory of Body Dysmorphic Disorder. It is most prevalent in males and has a number of cognitive, behavioral, socioenviornmental, emotional, and psychological factors that influence its expression. An etiological model describing these influences is presented for evaluation. Nine variables (body mass, media influences, ideal body internalization, low self-esteem, body dissatisfaction, health locus of control, negative affect, perfectionism, and body distortion) were identified through the use of extant literature on muscle dysmorphia and through extrapolation from literature involving women and eating disorders. The functional relationships among these variables are described and implications of the model are discussed.

Body Image↗
PubMed1982

Changes in myosin isozymes during development of chicken breast muscle.

The patterns of myosin isozymes in embryonic and adult chicken pectoralis muscle were examined by electrophoresis in a non-denaturing gel system (pyrophosphate acrylamide gel electrophoresis), and both light chains and heavy chains of embryonic and adult myosin isozymes were compared. In pyrophosphate acrylamide gel electrophoresis, the predominant isozyme component in embryonic pectoralis myosin could be clearly distinguished from adult myosin isozymes. SDS-polyacrylamide gel electrophoresis indicated that the light chain composition of embryonic myosin was also different from that of adult myosin. The pattern of peptide fragments produced by myosin digestion with a-chymotrypsin differed significantly between embryonic and adult skeletal myosin. These results suggest that myosin in the embryonic pectoralis muscle is different in both light and heavy chain composition from myosin in the same adult tissue.

Animals↗
PubMed1989

Expression of desmin and myoglobin in rhabdomyosarcomas and in developing skeletal muscle.

Immunohistochemical staining for desmin and myoglobin was investigated in 35 rhabdomyosarcomas from young people and in skeletal muscle from 16 human fetuses of known gestational age. Twenty-nine of the rhabdomyosarcomas expressed desmin but six undifferentiated or poorly-differentiated tumours were desmin negative. Of the desmin positive cases, most undifferentiated or poorly-differentiated sarcomas expressed desmin alone (12/35). Tumours with increasing rhabdomyoblastomic differentiation co-expressed myoglobin (9/35) and well-differentiated examples also contained cross-striations (7/35). Skeletal muscle from fetuses aged 8 weeks or less consisted mainly of primitive desmin negative round cells. As the cells began to differentiate they quickly expressed desmin and, at approximately 10 weeks, myoglobin was expressed and cross-striations were seen. The combined results strengthen the view that desmin (within a strictly defined context of round cell tumours in young people) is a reliable marker for rhabdomyoblastic differentiation. Support is also given to the notion that very primitive rhabdomyosarcomas may be desmin-negative, although the difficulties of establishing firm diagnoses for some of these tumours is emphasized.

Adolescent↗
PubMed2006

The Lutheran glycoprotein: a multifunctional adhesion receptor.

The Lutheran blood group system, which comprises one of the largest families of human red blood cell (RBC) antigens, resides on two immunoglobulin superfamily (IgSF) proteins: Lutheran and basal cell adhesion molecule (B-CAM). These two glycoproteins arise via alternative splicing of mRNA from a single gene and differ in structure only in the lengths of their cytoplasmic tails. Both are expressed on RBCs as well as a variety of other cell types, and they are overexpressed on sickle RBCs (SS RBC). B-CAM/Lu is the critical receptor for SS RBC adhesion to the extracellular matrix protein laminin, an interaction thought to contribute to the pathogenesis of sickle cell-related vasoocclusive events. Recent work has also shown that B-CAM/Lu on RBCs can undergo activation as a result of adrenergic signaling pathways. The high affinity of B-CAM/Lu for laminin is also thought to contribute to various developmental processes, including organogenesis, vascular development, erythropoiesis, and smooth muscle development and organization. Interestingly, the B-CAM spliceoform seems to be overexpressed by a variety of different malignant tumors and may be involved, along with other adhesion receptor proteins, in malignant transformation and tumor metastasis. Studies of B-CAM/Lu have thus expanded from defining antigen-specific polymorphisms to investigations of processes involved in sickle cell disease, human development, and cancer biology.

Amino Acid Sequence↗
PubMed1987

Two types of acetylcholine receptor channels in developing Xenopus muscle cells in culture: further kinetic analyses.

1. Further developmental changes in acetylcholine (ACh) receptor channel function were examined in Xenopus muscle cultures using the cell-attached patch-clamp technique. 2. Two types of acetylcholine (ACh) receptor channel events, low- and high-conductance channel events, were distinguished as reported earlier. Apparent open-time histograms for high-conductance channel events were well fitted by a single exponential but those for low-conductance channel events were sometimes fitted better by two exponentials. 3. In low-conductance channel events when the open-time histogram was well fitted by two exponentials, successive open times were correlated: an event with a long open time tended to be followed after a brief interval (less than 1 ms) by another long-duration event. A short-duration event was less frequently followed by an event within a short interval (1 ms) with a long-duration event. 4. Closed-time histograms for the interval between successive low-conductance channel events and between successive high-conductance channel events were both fitted by two exponentials. The fast time constant was 0.36 ms for the high-conductance channel event and 0.31 ms for the low-conductance channel event. There was an indication that a third and faster component was hidden in the first bin (0-200 microseconds) in the closed-time histogram of both types of channel events. 5. Defining a burst as successive openings separated by closures briefer than 1 ms, the number of gaps per burst was different for the two types of channel events. They were 0.16 for high- and 0.37 for low-conductance channel events. In both types of channels, neither the fast component in the closed-time histogram nor the number of gaps per burst changed with time in culture. 6. The apparent open time of both types of channels increased progressively as ACh concentration was increased, suggesting an increasing number of unresolved closures at higher concentrations. At 100 microM-ACh the apparent open time became shorter probably due to channel blockade by ACh molecules. Closed-time histograms were fitted by two exponentials. The time constant of the fast component remained similar to that at low concentration (0.2 microM) up to 20 microM, but the relative number of closures belonging to this component increased with ACh concentration. In contrast, the slow component shortened its time constant as ACh concentration increased and the relative frequency decreased. Again, there was an indication that another faster component existed in the closed-time histogram.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholine↗
PubMed1998

Mechanical loading regulates NOS expression and activity in developing and adult skeletal muscle.

The hypothesis that changes in muscle activation and loading regulate the expression and activity of neuronal nitric oxide (NO) synthase (nNOS) was tested using in vitro and in vivo approaches. Removal of weight bearing from rat hindlimb muscles for 10 days resulted in a significant decrease in nNOS protein and mRNA concentration in soleus muscles, which returned to control concentrations after return to weight bearing. Similarly, the concentration of nNOS in cultured myotubes increased by application of cyclic loading for 2 days. NO release from excised soleus muscles was increased significantly by a single passive stretch of 20% or by submaximal activation at 2 Hz, although the increases were not additive when both stimuli were applied simultaneously. Increased NO release resulting from passive stretch or activation was dependent on the presence of extracellular calcium. Cyclic loading of cultured myotubes also resulted in a significant increase in NO release. Together, these findings show that activity of muscle influences NO production in the short term, by regulating NOS activity, and in the long term, by regulating nNOS expression.

Aging↗