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At least 127 records · Page 7Linked to original sources
PubMed2005

A longitudinal evaluation of the skeletal profile of treated and untreated skeletal Class II individuals.

This study evaluated the changes in the skeletal profile of Class II subjects submitted to orthodontic treatment. The experimental group comprised the lateral cephalograms of 30 Brazilian subjects (17 female and 13 male subjects) obtained between the mean ages of 11.1 years (initial) and 15.1 years (final) and treated with cervical headgear and edgewise appliance. The control group comprised the lateral cephalograms of 30 Canadian individuals (13 females and 17 male individuals) at the ages of 6, 9, 12, 14, and 16 years from the Burlington Growth Study University of Toronto, Canada, who did not receive any kind of orthodontic treatment. The results demonstrated a reduction in the convexity of the skeletal profile of both groups. However, this change was only significant for the Canadian sample of 6- to 9-year olds (P < .01), whereas reduction was greater for the Brazilian group and was significant between the initial and final ages (P < .01). In the Canadian control group, the maxilla presented a tendency toward a forward displacement (P < .01), which was not observed in the experimental group (P < .01). The mandible presented a forward displacement in both groups; yet, only the Canadian group demonstrated a significant difference, which occurred between 9 and 16 years (P < or = .01).

Adolescent↗
PubMedDate not supplied

Skeletal immaturity, IGF-I and IGFBP-3 serum concentrations in Legg-Calvé-Perthes disease (skeletal immaturity, IGF-I and IGFBP-3 in LCPD).

BACKGROUND: Skeletal immaturity is a major feature in Legg-Calvé-Perthes disease (LCPD). Evaluation of growth hormone concentration, somatomedin activity, or insulin-like growth factor I (IGF-I) concentration revealed inconsistent results. Recently, IGF-binding protein 3 (IGFBP-3) was found normal in relation to chronological age in LCPD patients. PATIENTS: In this study IGF-I and IGFBP-3 were measured in the serum of 23 children with unilateral LCPD and in 23 sex and age matched controls. METHODS: IGF-I and IGFBP-3 were measured with radioimmunoassays, using an IGF binding site-blocked assay for IGF-I. The results were related to the chronological age in all and to the bone age in 19 of the patients. RESULTS: Bone age was retarded in 16 of 19 patients with a delay of one year or more in twelve children (mean 14.75, range 2-35 months). Chronological age and bone age related IGF-I and IGFBP-3 serum concentrations were predominantly within the normal ranges and did not differ significantly from the matched controls. IGF-I and IGFBP-3 serum levels showed a high correlation, which was similar in LCPD (r = 0.7; p < 0.0001) and in the control group (r = 0.8; p < 0.0001). CONCLUSIONS: Our data confirm that most children with LCPD are skeletally immature. However, IGF-I measured with IGF-II-blocked IGFBP binding sites, and IGFBP-3 serum concentrations analysed with respect to bone age show no evidence for a disturbance of the hypothalamo-pituitary-somatomedin axis in these children.

Age Determination by Skeleton↗
PubMed1985

[Skeletal manifestations of generalized mastocytosis in the skeletal scintigram compared with roentgen findings].

Bone scans and skeletal x-rays of eight patients with systemic mastocytosis were reviewed. Mast cell infiltration of bone marrow had been proven histologically in every patient. Bone scan and roentgenographic findings are not specific for the disease and do not correlate well in some patients. A generalized increase of uptake was noted in two patients, a generalized decrease of skeletal activity with poor delineation of bony structures was observed in others. A circumscribed increase of activity was observed in some patients, only one patient had a normal bone scan. Roentgenographic examination revealed diffuse sclerosis of trabecular bone in three patients, osteoporosis with collapse of multiple vertebral bodies in three patients, and no abnormalities in two patients.

Adult↗
PubMed1978

Specific phosphorylation at serine-283 of alpha tropomyosin from frog skeletal and rabbit skeletal and cardiac muscle.

Tropomyosin, extracted from the leg muscle of frogs that had been injected with [32P]orthophosphate, was fractionated into two components, alpha and beta, on a CM-cellulose column. Radioactivity was associated only with the alpha component. A single phosphorylation site was located at serine-283 (pentultimate at the COOH-terminal end) of the frog alpha tropomyosin. The same phosphorylated peptide was recovered in low yields from both rabbit skeletal alpha and cardiac tropomyosin. The presence of covalently bound phosphate in alpha tropomyosin and its absence in the beta component of rabbit skeletal muscle was suggested by 31P NMR spectroscopy. The amino acid sequences around the phosphorylation sites of frog and rabbit tropomyosin are identical. Because this sequence is not similar to any other known phosphorylation site in proteins, this indicates the existence of either specific kinase or phosphatase that can distinguish between alpha and beta tropomyosins. In a model proposed for the head-to-tail overlap of alpha tropomyosin molecules, one O-phosphoserine-283 residue could form a salt linkage with lysine-6 on one side of the overlap region and another with lysine-12 on the other side. This would predict a difference in the stability of polymers of phosphorylated and nonphosphorylated alphaalpha and alphabeta dimers of tropomyosin.

Amino Acid Sequence↗
PubMed2000

Skeletal muscle attenuation determined by computed tomography is associated with skeletal muscle lipid content.

The purpose of this investigation was to validate that in vivo measurement of skeletal muscle attenuation (MA) with computed tomography (CT) is associated with muscle lipid content. Single-slice CT scans performed on phantoms of varying lipid concentrations revealed good concordance between attenuation and lipid concentration (r(2) = 0.995); increasing the phantom's lipid concentration by 1 g/100 ml decreased its attenuation by approximately 1 Hounsfield unit (HU). The test-retest coefficient of variation for two CT scans performed in six volunteers was 0.51% for the midthigh and 0.85% for the midcalf, indicating that the methodological variability is low. Lean subjects had significantly higher (P < 0.01) MA values (49.2 +/- 2.8 HU) than did obese nondiabetic (39.3 +/- 7.5 HU) and obese Type 2 diabetic (33.9 +/- 4. 1 HU) subjects, whereas obese Type 2 diabetic subjects had lower MA values that were not different from obese nondiabetic subjects. There was also good concordance between MA in midthigh and midcalf (r = 0.60, P < 0.01), psoas (r = 0.65, P < 0.01), and erector spinae (r = 0.77, P < 0.01) in subsets of volunteers. In 45 men and women who ranged from lean to obese (body mass index = 18.5 to 35.9 kg/m(2)), including 10 patients with Type 2 diabetes mellitus, reduced MA was associated with increased muscle fiber lipid content determined with histological oil red O staining (P = -0.43, P < 0. 01). In a subset of these volunteers (n = 19), triglyceride content in percutaneous biopsy specimens from vastus lateralis was also associated with MA (r = -0.58, P = 0.019). We conclude that the attenuation of skeletal muscle in vivo determined by CT is related to its lipid content and that this noninvasive method may provide additional information regarding the association between muscle composition and muscle function.

Adult↗
PubMed1989

Contribution of intrinsic skeletal muscle changes to 31P NMR skeletal muscle metabolic abnormalities in patients with chronic heart failure.

Patients with heart failure frequently exhibit abnormal skeletal muscle metabolic responses to exercise, as assessed with 31P NMR. To investigate whether these metabolic abnormalities are due to intrinsic skeletal muscle changes, we performed gastrocnemius muscle biopsies on 22 patients with heart failure (peak VO2, 15.4 +/- 4.7 ml/kg/min; ejection fraction, 20 +/- 7%) and on eight normal subjects. Biopsies were analyzed for fiber type and area, capillarity, citrate synthase, phosphofructokinase, lactate dehydrogenase, and beta-hydroxyacyl CoA dehydrogenase activity. All patients with heart failure also underwent 31P NMR studies of their calf muscle during plantarflexion at three workloads. Muscle pH responses and the relation of the ratio of inorganic phosphate to phosphocreatine (Pi/PCr) to systemic VO2 were then evaluated. Compared with normal subjects, patients with heart failure exhibited a shift in fiber distribution with increased percentage of the fast twitch, glycolytic, easily fatigable type IIb fibers (normal subjects, 22.7 +/- 10.1; heart failure, 33.1 +/- 11.1%; p less than 0.05), atrophy of type IIa (normal subjects, 5,477 +/- 1,109; heart failure, 4,239 +/- 1,247 microns 2; p less than 0.05) and type IIb fibers (normal subjects, 5,957 +/- 1,388; heart failure, 4,144 +/- 945 microns 2; p less than 0.01), and decreased activity of beta-hydroxyacyl CoA dehydrogenase (normal subjects, 5.17 +/- 1.44; heart failure, 3.67 +/- 1.68 mol/kg protein/hr; p less than 0.05). No significant linear correlation could be identified between the slope of the Pi/PCr to VO2 relation and muscle histochemistry or enzyme activities. Similarly, no linear relation was found between intracellular pH at peak exercise and any muscle variable.(ABSTRACT TRUNCATED AT 250 WORDS)

Biopsy↗
PubMed1993

A murine skeletal adaptation that significantly increases cortical bone mechanical properties. Implications for human skeletal fragility.

Mov13 mice carry a provirus that prevents transcription initiation of the alpha 1(I) collagen gene. Mutant mice homozygous for the null mutation produce no type I collagen and die at mid-gestation, whereas heterozygotes survive to adulthood. Dermal fibroblasts from heterozygous mice produce approximately 50% less type I collagen than normal littermates, and the partial deficiency in collagen production results in a phenotype similar to osteogenesis imperfecta type I (an inherited form of skeletal fragility). In this study, we have identified an adaptation of Mov13 skeletal tissue that significantly improves the bending strength of long bone. The adaptive response occurred over a 2-mo period, during which time a small number of newly proliferated osteogenic cells produced a significant amount of matrix components and thus generated new bone along periosteal surfaces. New bone deposition resulted in a measurable increase in cross-sectional geometry which, in turn, led to a dramatic increase in long bone bending strength.

Aging↗
PubMed1990

Expression and localization of the two small proteoglycans biglycan and decorin in developing human skeletal and non-skeletal tissues.

The messenger RNAs and core proteins of the two small chondroitin/dermatan sulfate proteoglycans, biglycan and decorin, were localized in developing human bone and other tissues by both 35S-labeled RNA probes and antibodies directed against synthetic peptides corresponding to nonhomologous regions of the two core proteins. Biglycan and decorin expression and localization were substantially divergent and sometimes mutually exclusive. In developing bones, spatially restricted patterns of gene expression and/or matrix localization of the two proteoglycans were identified in articular regions, epiphyseal cartilage, vascular canals, subperichondral regions, and periosteum, and indicated the association of each molecule with specific developmental events at specific sites. Study of non-skeletal tissues revealed that decorin was associated with all major type I (and type II) collagen-rich connective tissues. Conversely, biglycan was expressed and localized in a range of specialized cell types, including connective tissue (skeletal myofibers, endothelial cells) and epithelial cells (differentiating keratinocytes, renal tubular epithelia). Biglycan core protein was localized at the cell surface of certain cell types (e.g., keratinocytes). Whereas the distribution of decorin was consistent with matrix-centered functions, possibly related to regulation of growth of collagen fibers, the distribution of biglycan pointed to other function(s), perhaps related to cell regulation.

Adrenal Glands↗
PubMed2003

[Comparison of craniofacial skeletal structures in adult high-angle and low-angle facial skeletal types].

OBJECTIVE: The purpose of this study was to compare the differences of craniofacial characteristics of adult high-angle and low-angle facial skeletal types. METHODS: The subjects consisted of 37 yellow race adults (17 high-angle, 20 low-angle). Fifty-three items of cephlometic radiographs were analyzed. RESULTS: The angle of N-S-Ar and N-S-Ba, the distance of Ptm-A, Co-Go, Po-NB, and S-Go, and the thickness of the mandibular symphysis in high-angle group were smaller than these in low-angle group. The angles of SN-OP, FH-OP, PP-OP, SN-MP, FH-MP, PP-MP, S-Ar-Go, mandibular angle(Ar-Go-Me), Y-angel and SUM, the distance of S-Co, N-Me, and ANS-Me in high-angle group were greater than these in low-angle group. The index of FHI, N-ANS/N-Me, and N-ANS/ANS-Me were smaller, and ANS-Me/N-Me larger in high-angle group. Although the means of Go-Po and FH-RP were smaller in high angle group, but no statistical difference were found. CONCLUSION: The craniofacial morphology of adult high-angle and low-angle facial skeletal types demonstrated significant differences, especially in lower facial form.

Adolescent↗
PubMed2002

The health of the human skeletal system for weight bearing against gravity: The role of deloading the musculo-skeletal system in the development of musculoskeletal injury.

Musculo-skeletal disease is a major health problem which continues to increase in developed countries. A mechanism related hypothesis is presented to explain why most musculo-skeletal injury has an insidious onset and is not linked to a single traumatic event. The hypothesis predicts a close link between a dysfunction in the antigravity muscle system, which protects joints from injury, and the development of musculoskeletal disease patterns.

Journal Article↗
PubMed1991

[Cardiac assist device with skeletal muscle ventricle--alternate-drive twin pump system as a countermeasure to prevent skeletal muscle fatigue].

Many studies on cardiac assist devices using skeletal muscle ventricle (SMV) require preconditioning for 6-9 weeks as a countermeasure to prevent skeletal muscle fatigue. Therefore this method does not seem to be indicated in cases of acute heart failure. However we performed experiments to develop Alternate-Drive Twin SMVs as a cardiac assist device without preconditioning. Adult mongrel dogs were used. In order to obtain adequate alternating SMV during pattern, fundamental experiments were performed. The function of SMVs prepared by rolled pedunculated sartial muscle was studied hydrodynamically in three groups; continuous driving for one hour in group a (n = 3): intermittent driving for 3 hours in group b (n = 15): intermittent driving for 12 hours in group c (n = 3). Group b was divided into three subgroups with interval for 10 minutes in subgroup I (n = 5), for 20 minutes in subgroup II (n = 5), for 30 minutes in subgroup III (n = 5). In group b and c, the recess interval between driving was set the same as the driving interval in each subgroup. All SMVs were stimulated by electrical bursts. In every experiment pump pressure, pump max dp/dt and pump stroke work index/10 kg body weight were measured for 3 hours. In subgroups I and II, pump function decreased gradually, however, the parameters did not show any change for up to 3 hours in subgroup III. We defined the reduction ratio as the difference of parameters before and after driving divided by the value at the start of driving.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Investigation of the functional treatment effects of the skeletal and dental Class III anomalies on the skeletal region].

This study was carried out on two groups with skeletal and dental Class III malocclusion. There were 21 patients in the first group (10 females and 11 males) on which the chin-cap treatment was performed and average age of these was 11 years and mean treatment period was 0.7 years. The second group which consisted of 9 individuals was the control group and none of them had any orthodontic treatment. The control group consisted of 5 females and 4 males individuals and average age was 9.7 years and mean control period was 2 years. This investigation was performed on 60 cephalometric films obtained from both groups. 6 angular, 5 dimensional total 11 skeletal cephalometric measurements were performed on these films. When these groups were compared according to these measurements it was found that there was a decrease in SNB, SN/ANS-PNS angles also a decrease was detected in distances between Pg-Ramus Inferior tangent point, Pg-Ramus Superior tangent point, Cd-Pg points. On the other hand there was an increase in ANB angle and Wits appraisal which is the dimensional expression of ANB angle.

Cephalometry↗
PubMed1987

Influence of the dwarf mouse mutation on skeletal and cardiac myosin isoforms. Effect of one injection of thyroxine on skeletal and cardiac muscle phenotype.

The dwarf mutant is an autosomal recessive mutation of the mouse which causes a defective development of those anterior pituitary cells responsible for the production of thyroid-stimulating hormone, growth hormone, and prolactin. These mice are thus genetically hypothyroid and provide a model system in which one can investigate the influence of thyroid hormone on the transitions of the myosin heavy chain isoforms. We have carried out a qualitative and quantitative investigation of the myosin heavy chain isoforms present at various developmental stages and following one injection of 1 microgram of thyroxine. Myosin heavy chains were identified by nondissociating gel electrophoresis, localized by indirect immunofluorescence, and quantitated by the enzyme-linked immunosorbent assay technique. We find that in skeletal muscle, the appearance of the adult fast myosin heavy chain is severely retarded, that the neonatal myosin heavy chain is never totally eliminated, and that there is an overall increase in the number of fibers containing slow myosin heavy chain. In cardiac tissue the adult phenotype is never attained and beta-cardiac myosin heavy chain remains the predominant isoform. A single injection of 1 microgram of thyroxine was sufficient to cause a slight acceleration in the appearance of the adult fast myosin heavy chain in skeletal muscle, but only after 6-8 days. However, in the cardiac muscle, one injection of thyroxine resulted in a more rapid but transient expression of the alpha-cardiac myosin heavy chain, suggesting that the mechanism of action of thyroid hormone is different in these two tissues.

Aging↗
PubMed1986

Substrate regulation of the glucose transport system in rat skeletal muscle. Characterization and kinetic analysis in isolated soleus muscle and skeletal muscle cells in culture.

A self-regulatory mechanism of the glucose transport in rat skeletal muscle cells is described. In isolated rat soleus muscles and rat skeletal myocytes and myotubes in culture, pre-exposure to varying glucose concentrations modulated the rate of 2-deoxyglucose uptake. Maximal uptake was observed at glucose concentrations below 3 mM. Between 2.5 and 4.0 mM glucose it was reduced by 25-35%; further elevation of the glucose concentration resulted in a gradual decrease of the transport rate by approximately 2% for each millimolar glucose. The effect of glucose was time-dependent and fully reversible. Insulin rapidly increased the 2-deoxyglucose uptake in the soleus muscle; however, the insulin effect depended on the glucose concentration of the preincubation. Insulin was totally ineffective in muscles pre-exposed to 1.0-3.0 mM glucose, whereas its stimulatory action increased with increasing glucose concentrations above 4 mM. The effect of low glucose and insulin were not additive, and the maximal 2-deoxyglucose uptake rates induced by both conditions were of identical magnitude. It is postulated that glucose may "up- and down-regulate" its transport by affecting the number of active glucose transporters in the plasma membrane, and that insulin exerts its stimulatory effect only when the extracellular glucose reaches a threshold concentration.

Aminoisobutyric Acids↗
PubMed1982

Leucine incorporation into skeletal muscle proteins in vitro and protein synthesis by isolated ribosomes from skeletal muscle around a high velocity missile injury.

Protein synthesis in skeletal muscle around a high velocity missile injury was investigated in two series of experiments. In the first series a shot wound was induced in the hindleg of dogs. Muscle biopsies were taken at various distances from the wound channel and bundles of muscle fibre were incubated in a medium containing 14C-leucine under protein synthetizing conditions. A significant reduction in the rate of leucine incorporation into muscle protein was seen in the adjacent to the wound channel. At a distance of 3 cm from the bullet track no reduction in leucine incorporation into protein occurred. In the second series of experiments a high velocity missile injury was induced in the hindleg of pigs. The capacity of ribosomes to incorporate 14C-phenylalanine into protein was analyzed. Ribosomes were isolated from skeletal muscle around the shot wound. The effect of missile injury alone and that of the combined effect of missile injury and hemorrhage were studied. A marked reduction in ribosomal activity was found in tissue adjacent to and up to 2.4 cm from the wound channel. At a distance of 3 cm from the wound ribosomal activity remained unaffected. Ribosomal activity was significantly more reduced in tissue close to the wound channel after missile injury and hemorrhage than after missile injury alone. The reduced capacity for protein synthesis in muscle around the missile injury found in this study probably reflects a lowered cellular energy level. The local metabolic changes were aggrevated in animals where hemorrhage was also induced indicating that in the clinical situation prevention of hemorrhage and hypovolemia might reduce the amount of tissue that has to be excised following a short wound.

Animals↗
PubMed1976

[Several biochemical characteristics of rat skeletal musculature during the development under conditions of skeletal muscular loading and hypodynamia].

The weight and biochemistry of the skeletal muscles of rats developing under conditions of the action of the skeletomuscular loads (the I group), under conditions of hypodynamia - at the environmental temperature of 20-22 degrees C (the II group) and at the environmental temperature of 28-30 degrees C (the III group) were studied. Rats of the I group displayed an increase of the mass of the skeletal muscles and also an elevation of protein, glycogen, ATP, creatine phosphate and a decrease of lactic acid content in these muscles. Rats of the III group showed a considerable decrease in the content of enumerated indices both in comparison with indices of control animals and of rats of the I group. This decrease was less marked in rats of the II group.

Animals↗
PubMed1996

Sodium channel slow inactivation and the distribution of sodium channels on skeletal muscle fibres enable the performance properties of different skeletal muscle fibre types.

Na+ currents (INa) and membrane capacitance were studied with the loose patch voltage clamp technique and action potential properties were studied with a two-electrode voltage clamp on the end-plate, at the end-plate border and on extrajunctional membrane of skeletal muscle fibres. Slow inactivation regulates the available INa and is operative at the resting potential of both rat and human fibres. At the resting potential, slow inactivation causes a greater reduction in INa in fast-than in slow-twitch fibres. The relative resistance of slow-twitch fibres to slow inactivation may enable slow-twitch fibres to remain tonically active. Na+ channel inactivation may provide a peripheral mechanism that limits the duration that fast-twitch fibres can fire at high rates to prevent injury associated with prolonged high-frequency contraction. Consequently, slow inactivation may enable fast-twitch fibres to operate phasically at high rates or slow-twitch fibres to fire continuously at lower rates. For both fast- and slow-twitch fibres. INa normalized to membrane area was greatest on the end-plate, intermediate on the end-plate border and smallest on extrajunctional membrane. When normalized to membrane capacitance. INa was the same on the end-plate and the end-plate border and smallest on extrajunctional membrane. For a given membrane region, INa was larger on fast- than on slow-twitch fibres. The higher density of Na+ channels near the end-plate increased the safety factor for neuromuscular transmission by lowering the action potential threshold and increasing the action potential rate of rise at the end-plate.

Action Potentials↗
PubMed2004

Cardiac troponin C (TnC) and a site I skeletal TnC mutant alter Ca2+ versus crossbridge contribution to force in rabbit skeletal fibres.

We studied the relative contributions of Ca(2+) binding to troponin C (TnC) and myosin binding to actin in activating thin filaments of rabbit psoas fibres. The ability of Ca(2+) to activate thin filaments was reduced by replacing native TnC with cardiac TnC (cTnC) or a site I-inactive skeletal TnC mutant (xsTnC). Acto-myosin (crossbridge) interaction was either inhibited using N-benzyl-p-toluene sulphonamide (BTS) or enhanced by lowering [ATP] from 5.0 to 0.5 mm. Reconstitution with cTnC reduced maximal force (F(max)) by approximately 1/3 and the Ca(2+) sensitivity of force (pCa(50)) by 0.17 unit (P < 0.001), while reconstitution with xsTnC reduced F(max) by approximately 2/3 and pCa(50) by 0.19 unit (P < 0.001). In both cases the apparent cooperativity of activation (n(H)) was greatly decreased. In control fibres 3 mum BTS inhibited force to 57% of F(max) while in fibres reconstituted with cTnC or xsTnC, reconstituted maximal force (rF(max)) was inhibited to 8.8% and 14.3%, respectively. Under control conditions 3 mum BTS significantly decreased the pCa(50), but this effect was considerably reduced in cTnC reconstituted fibres, and eliminated in xsTnC reconstituted fibres. In contrast, when crossbridge cycle kinetics were slowed by lowering [ATP] from 5 to 0.5 mm in xsTnC reconstituted fibres, pCa(50) and n(H) were increased towards control values. Combined, our results demonstrate that when the ability of Ca(2+) binding to activate thin filaments is compromised, the relative contribution of strong crossbridges to maintain thin filament activation is increased. Furthermore, the data suggest that at low levels of Ca(2+), the level of thin filament activation is determined primarily by the direct effects of Ca(2+) on tropomyosin mobility, while at higher levels of Ca(2+) the final level of thin filament activation is primarily determined by strong cycling crossbridges.

Actins↗