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PubMed1972

Effect of insulin on protein synthesis in skeletal muscle of an isolated perfused preparation of rat hemicorpus.

A method for perfusion in vitro of a preparation of rat hemicorpus was developed for study of the metabolism of skeletal muscle. The preparation was stable during perfusion, as indicated by maintenance of ATP concentration, perfusion pressure, and oxygen consumption for up to 90 min. The perfused hemicorpus provided the following advantages for study of protein synthesis in skeletal muscle: (a) hormones and substrates reached the muscle cells through an intact capillary bed, and (b) the preparation included the psoas muscle, which was sufficiently large to allow measurements of intermediates in the pathway of protein synthesis and was readily homogenized for preparation of ribosomes and ribosomal subunits. Perfusion of psoas muscle from fasted rats with buffer containing glucose and insulin reduced the concentration of ribosomal subunits and increased phenylalanine incorporation as compared to perfusion with buffer containing glucose alone. In addition, the hormone increased glucose uptake from the perfusate and inhibited release of free fatty acids from the preparation. When the muscle was perfused with buffer that contained glucose and palmitate, the concentration of ribosomal subunits and phenylalanine incorporation were unchanged. Since fatty acid is known to stimulate protein synthesis in heart muscle, these results indicated that rates of protein synthesis in heart, but not in skeletal, muscle would be maintained during fasting or in diabetic animals by increased plasma concentration of fatty acid.

Adenosine Triphosphate↗

PubMedDate not supplied

[An indirect proof of stretch-induced Ca++ release from the sarcoplasmic reticulum in glycerinated skeletal and heart muscle preparations (author's transl)].

The existence of still functioning vesicles of the sarcoplasmic reticulum (SR) in glycerinated rabbit psoas muscle fibers and cat myocardium is demonstrated by the use of activation (force development and shortening) of the contractile system as an indicator for "sarcoplasmic", free Ca++ concentration and by electron microscopic studies. Furthermore, the conditions for Ca++ release and uptake by the SR vesicles were analyzed. (1) As indicated by electron microscopic studies, glycerinated skeletal and heart muscle preparations contain SR vesicles (diameter 0.1--0.2 mu). Detergent treatment as used by Julian (1971) causes neither morphological change in the contractile system nor in the SR vesicles. (2) The delay in tension development of glycerinated preparations after an increase in free Ca++ concentration of the bathing medium is demonstrated to be caused at least partly by Ca++ uptake in these SR vesicles. (3) The SR vesicles of glycerinated preparations are able to accumulate Ca++ just at concentrations which are subthreshold for tension development. The accumulated Ca++ can be detected by a transient force development resulting from abolishment of the Ca++ storage capacity of the SR vesicles caused by high concentrations of detergents. (4) Ca++-induced Ca++ release is also demonstrated in glycerinated preparations. After Ca++ loading this release mechanism occurs at Ca++ concentrations in the bathing medium starting at about 10(-7,48) Mol/l both in skeletal and heart muscle preparations. (5) Quick stretch of Ca++-loaded, relaxed preparations caused local contractions of the myofibrils in both single fibers and fiber bundles of glycerinated rabbit psoas muscle. Skeletal fiber bundles and cat myocardium show a transient tension development parallel to these local contractions. These effects are demonstrated to be due to a stretch-induced Ca++ release from the SR vesicles. (6) Length-controlled quick stretches or quick releases of partly activated preparations cause sinusoidal tension oscillations superimposed on the well-known, delayed active tension development. In contrast, fully activated preparations do not show superimposed oscillations in tension. Force-controlled quick stretches or quick releases induce equivalent oscillations in length which are more distinct than the tension oscillations, however. These oscillations are also demonstrated to be due to stretch or release-induced changes in the Ca++ fluxes between SR vesicles and the "sarcoplasm". (7) This stretch induced release of Ca++ from the SR could be one reason for the multiple-phase course of active and passive isometric tension development in vivo following quick changes in length, and could also partly explain the prestretch dependence of tension development which cannot be explained from the degree of overlapping of the contractile filaments alone...

Animals↗

PubMed1997

Differences in myosin head arrangement on relaxed thick filaments from Lethocerus and rabbit muscles.

Relaxed thick filaments from insect asynchronous flight muscle appear different from those of other striated muscles, both in sections and as separated, negatively-stained structures. Unlike relaxed filaments of scallops, chelicerate arthropods, or vertebrate striated muscle, all of which display a predominantly helical arrangement of surface myosin heads, insect asynchronous flight muscle filaments appear striped, with cross-striations or shelves at spacings of 14.5 nm. Using a bifunctional agent to cross-link the active sites of nearest-neighbour myosin heads we previously demonstrated that the helical arrays on the surfaces of scallop, arthropod, fish and frog filaments are produced by the association of two oppositely-oriented myosin heads, each of which originates from an axially sequential molecule within the same helical strand. The effect of similarly cross-linking nearest-neighbour heads with the bifunctional agent 3,3'-dithiobis[3'(2')-O-(6-propionylamino)hexanoyl]adenosine 5'-triphosphate in the presence of vanadate on the solubility of thick filaments separated from Lethocerus indirect flight muscle (an insect asynchronous flight muscle) and rabbit psoas muscle was examined. After incubation on high salt, treated rabbit filaments retained their length and surface myosin, while untreated filaments and those with severed cross-links dissolved, indicating that the myosin head arrangement on rabbit filaments is similar to those previously studied. Treated indirect flight muscles filaments, however, separated into distinct segments of variable lengths, usually multiples of 150 nm, while untreated filaments and those with severed cross-links dissolved completely. This implies that intermolecular associations on indirect flight muscles filaments most likely occur between circumferentially-adjacent heads within each crown, but originating from different helical strands. We interpret this difference in the relaxed orientations of splayed myosin heads on the two types of filament as reflecting a difference in functional requirements at the onset of, or during, contractile activity.

Actin Cytoskeleton↗

PubMed1999

Obturator internus muscle abscess in children: report of seven cases and review.

Obturator internus muscle (OIM) abscess is an uncommon entity often mistaken for septic arthritis of the hip. We describe seven children with OIM abscess and review seven previously reported cases. The most common presenting symptoms were hip or thigh pain (14 patients), fever (13), and limp (13). The hip was flexed, abducted, and externally rotated in 11 patients. Magnetic resonance imaging and computed tomography (CT) were diagnostic for OIM abscess in the 14 patients. Associated abscesses were located in the obturator externus muscle (5 patients), psoas muscle (2), and iliac muscle (1). The etiologic agents were Staphylococcus aureus (8 patients), Streptococcus pyogenes (2), Neisseria gonorrhoeae (2), and Enterococcus faecalis (1). Three patients underwent CT-guided percutaneous drainage, and three had surgical drainage. Three patients had ischial osteomyelitis in addition to OIM abscess. The 11 children with uncomplicated OIM abscess were treated for a median of 28 days. All patients had an uneventful recovery.

Abscess↗

PubMed1983

Troponin subunit stoichiometry and content in rabbit skeletal muscle and myofibrils.

The quantity and molar ratio of the three troponin subunits to actin were determined in rabbit psoas muscle, muscle homogenates (800 X g pellet), and purified myofibrils. Proteins were separated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The quantities of the separated proteins were determined directly from the gel slices by amino acid analysis after correction for losses and background. The molar ratio of actin, troponin T, troponin I, and troponin C was found to be 6.99:1:05:1:04:0.92 in purified myofibrils and was not significantly different (p greater than 0.05) from those obtained from 800 X g pellets of muscle homogenates or intact muscle tissue. Isolated troponin purified by several different procedures also had a 1:1:1 subunit ratio although the variability was much greater than that found in myofibrils. The troponin content of rabbit psoas muscle and myofibrils was 91 +/- 16 and 770 +/- 110 pmol/mg, respectively.

Actins↗

PubMed2001

[Hydatid cyst of the psoas. Report of a case].

The authors report a case of hydatid cyst of the psoas muscle in 23 years old woman who presented a left lumboiliac mass. Ultrasonography and computed tomography contributed to the preoperative diagnosis. The cyst was removed by retroperitoneal approach by left lumbotomy. In the light of this case and the literature data, the authors discuss the diagnosis and therapeutic problems raised by hydatid cyst of the psoas muscle.

Adult↗

PubMed1987

Comparative histochemistry of a flatfish fin muscle and of other vertebrate muscles used for ultrastructural studies.

Because of the high degree of filament order in the myofibrils of fish skeletal muscles, and the resulting usefulness of such preparations (particularly flatfish fin muscles) in structural studies of muscular contraction, the fibre type composition of plaice fin muscle has been determined by conventional histochemical tests. As controls, and for comparison, fibre type distributions have also been studied in several other vertebrate skeletal muscles which are widely used for ultrastructural and mechanical studies. In view of the importance of single fibres in such studies and because much of the published information on fibre types is rather difficult to collate, we summarize here the fibre compositions of several muscles; comparable enzyme tests have been carried out on cryostat sections of rabbit psoas muscle, frog sartorius and semitendinosus muscles and plaice fin muscles. On this basis all four muscles are composed of more than one fibre type. We confirm that frog sartorius muscle is mainly a random mixture of two fast fibre types and show that there is also a third group of fibres which are small, metabolically rich and dark under acid m-ATPase tests. We confirm that the semitendinosus is composed of three fibre types, in three non-exclusive, concentric regions and that rabbit psoas muscle contains a mixture of at least three fibre types. The principal new findings of this work are that plaice fin muscle can be divided into four regions, some of which are composed of more than one fibre type, on the basis of its histochemical reactions. This division into regions changes seasonally. The system of classification devised by Dubowitz & Brooke (1973) for mammalian muscle, and which can be applied approximately to frog muscle, can also be applied to the fibres of plaice fin muscle provided that the test for lactate dehydrogenase is carried out in the presence of polyvinyl alcohol. These fibres do not easily fit the division into red, white and intermediate types normally used for fish myotomal muscles. Since none of these muscles is homogeneous, their complex nature must be borne in mind if they are to be used satisfactorily in structural and mechanical studies of muscular contraction involving the use of single fibres.

Adenosine Triphosphatases↗

PubMed1992

Lumbar disc and back muscle degeneration on MRI: correlation to age and body mass.

Lumbar intervertebral discs and paraspinal muscles in 74 healthy volunteers ranging in age from 19 to 74 years were evaluated with MRI, and the occurrence of degeneration was correlated to age and body mass. Muscle size and the amount of fat in the muscles was studied from MRI cross sections. When the back muscles were degenerated, they were small and contained fat deposits. By contrast, the psoas muscles never showed gross fat deposits. Degeneration of both the lumbar discs and muscles increased with age. No correlation was found between muscle degeneration and overweight. Muscle degeneration is as common as disc degeneration in the lumbar area. MRI is an excellent method to assess both muscle and disc degeneration.

Adipose Tissue↗

PubMed1995

The relations between physical ability and bone mass in women aged over 65 years.

In this cross-sectional study of 55 women (mean age 73.54 +/- 5.87), the magnitude of the relation between different indices of physical ability and confounding factors to bone density were determined. Physical fitness was assessed by direct measurement of maximal oxygen consumption (VO2 max), isokinetic muscle strength, and quadriceps and psoas muscle surfaces and densities using computed tomography. Anthropometry, chronological and gynecological ages, and dietary calcium intake were also recorded. The bone mineral density (BMD) was evaluated at the axial level (lumbar spine and proximal femur) and at the peripheral level (radius and tibia, cancellous and cortical compartments). Parameters related to physical ability proved to be the best predictors of BMD in radial and tibial cancellous compartments, spine, femoral neck, and trochanter, accounting for 15-27.5% of the total variance. The VO2 max was a major determinant of the femoral mineral density and one of the predictors of radial and tibial cancellous compartments. Psoas parameters were strongly related to spine mineral density and also constituted a predictor of radius (cancellous) and tibia mineral densities. The arm muscle strength could predict, though weakly, the BMD of axial skeleton, whereas thigh muscle strength only predicted the BMD of inferior limbs. No correlation was observed between current dietary calcium intake and BMD. Age-postmenopause and fertile life remained predictive of BMD at mostly cancellous sites, whereas anthropometry exerted important effects on radial and tibial cortices. The study suggests distinct sets of relations between physical ability and the BMD variables. Subjects with greater and denser psoas muscles had greater spine BMD, and those with higher VO2 max had greater proximal femur BMD.

Absorptiometry, Photon↗

PubMed2001

Comparison of the clinical and laboratory features of muscle infections caused by Salmonella and those caused by other pathogens.

Muscle infections caused by Salmonella constitute an uncommon complication of extraenteric salmonellosis. The aim of this study was to compare the clinical features of Salmonella muscle infections with those reported in several large series of typical, both tropical and non-tropical, pyomyositis, caused mostly by Staphylococcus aureus. A literature survey of Salmonella muscle infections was carried out by using MEDLINE files 1966 through 2000, and cross-references from the selected articles, as well as major reviews of Salmonella infections and of pyomyositis. The survey yielded 32 cases suitable for analysis. The sex distribution, duration of symptom at presentation, degree of fever, involvement of multiple muscle groups, and leukocyte counts were not significantly different between patients with muscle infections caused by Salmonella and typical pyomyositis patients. In contrast, the median age of the patients with Salmonella muscle infections, and the rate of underlying conditions, were significantly higher than those in typical pyomyositis. Psoas muscle was involved more commonly in Salmonella infections than in typical pyomyositis, and the yield of positive blood cultures and, particularly, the mortality rate, were substantially higher in Salmonella muscle infections than in typical pyomyositis. We conclude that patients with Salmonella muscle infections seem to have some different characteristics with respect to typical pyomyositis, such as older age, and higher rates of associated conditions, psoas muscle involvement, bacteremia, and mortality.

Female↗

PubMed1995

Differences in diaphragm fiber types in SIDS infants.

The diaphragm is a vital respiratory muscle in the sleeping infant. Any changes in diaphragm fiber type number or size could represent either a primary developmental delay or a secondary reaction to increased workload, and could give a clue as to the pathogenesis of sudden infant death syndrome (SIDS). We therefore quantitated by point counting on ATPase histochemistry the numbers and areas of type 1 and 2 fibers in the diaphragm, external intercostal and psoas muscles of 37 SIDS and 20 control infants. The amount of slow, fast and fetal myosin in the diaphragm and psoas muscles was measured by electrophoresis to check the ATPase quantitation. There were fewer type 1 fibers in SIDS (median 30.0%) compared with control (median 40.0%) infants (p < 0.02), whereas the diameter of type 1 fibers in SIDS (median 33.9 microns) was larger than in control (median 30.3 microns) infants (p < 0.007). The total cross-sectional area occupied by type 1 and 2 fibers was similar in both groups. No changes were found in the external intercostal or psoas. The amount of slow and fast myosins correlated well with type 1 and type 2 fibers, respectively. The finding of fewer type 1 (fatigue-resistant) fibers of large diameter in SIDS diaphragms suggests that differences in muscle fiber types may predispose these infants to diaphragm fatigue and respiratory failure.

Diaphragm↗

PubMed2003

Thin filament activation and unloaded shortening velocity of rabbit skinned muscle fibres.

The unloaded shortening velocity of skinned rabbit psoas muscle fibres is sensitive to [Ca2+]. To determine whether Ca2+ affects the unloaded shortening velocity via regulation of crossbridge kinetics or crossbridge number, the shortening velocity was measured following changes in either [Ca2+] or the number of active thin filament regulatory units. The native troponin C (TnC) was extracted and replaced with either cardiac TnC (cTnC) or a mixture of cTnC and an inactive mutant cardiac TnC (CBMII TnC). The unloaded shortening velocity of the cTnC-replaced fibres was determined at various values of [Ca2+] and compared with different cTnC:CBMII TnC ratios at a saturating [Ca2+]. If Ca2+ regulates the unloaded shortening velocity via kinetic modulation, differences in the velocity-tension relationship between the cTnC fibres and the cTnC:CBMII TnC fibres would be apparent. Alternatively, Ca2+ control of the number of active crossbridges would yield similar velocity-tension relationships when comparing the cTnC and cTnC:CBMII TnC fibres. The results show a decline in the unloaded shortening velocity that is determined by the relative tension, defined as the level of thin filament activation, rather than the [Ca2+]. Furthermore, at lower levels of relative tension, the reduction in unloaded shortening is not the result of changes in any cooperative effects of myosin on Ca2+ binding to the thin filament. Rather, it may be related to a decrease in crossbridge-induced activation of the thin filament at the level of the individual regulatory unit. In summary, the results suggest that Ca2+ regulates the unloaded shortening velocity in skinned fibres by reducing the number of crossbridges able to productively bind to the thin filament without affecting any inherent property of the myosin.

Actin Cytoskeleton↗

PubMed1994

Contractile activation and force generation in skinned rabbit muscle fibres: effects of hydrostatic pressure.

1. Effects of hydrostatic pressure (range 0.1-10 MPa) on the isometric tension of skinned (rabbit psoas) muscle fibres were examined at 12 degrees C and at different levels of Ca2+ activation (pCa range 4-7); the effects on both the steady tension and the tension transients induced by rapid pressure release (< 1 ms) are described. 2. The steady tension was depressed by increased pressure (approximately 1% MPa-1) at a high level of Ca2+ activation (pCa approximately 4) whereas it was potentiated at lower Ca2+ levels (pCa > 6); the effects were reversible. 3. At maximal Ca2+ activation, the tension recovery following pressure release (10 MPa to atmospheric) consisted of a fast (approximately 30 s-1) and a slow (2-3 s-1) phase; the rate and the normalized amplitude (normalized to the steady tension at atmospheric pressure for a particular pCa) of the fast phase were invariant with changes in Ca2+ level. 4. The effects of changing Ca2+ level on the slow phase were complex; its positive amplitude at high Ca2+ levels changed to negative and the rate decreased to approximately 1 s-1 at low Ca2+ levels (pCa > 6.0). 5. Results are discussed in relation to previous studies on the effect of pressure on intact muscle fibres and the actin-myosin interaction. This work supports calcium regulation of cross-bridge recruitment rather than calcium regulation of the rate of a specific step in the cross-bridge cycle.

Animals↗

PubMed2002

Initial results of the effects of diuresis on gadolinium enhancement in MR imaging of the abdomen.

RATIONALE AND OBJECTIVES: The authors performed this study to assess the effects of furosemide-induced diuresis on paramagnetic contrast material enhancement at magnetic resonance (MR) imaging of the kidney, liver, spleen, and psoas muscle. MATERIALS AND METHODS: Twenty-five patients (average age, 44.9 years; age range, 23-74 years; 13 men, 12 women) who were suspected of having unilateral renal hydronephrosis received 0.1 mmol/kg contrast material with a standardized injection and imaging protocol to assess organ signal intensity at 0-5 minutes after injection. All patients had a normal serum creatinine level. Imaging was performed with a 1.5-T magnet by using a fat-suppressed fast spoiled gradient-echo pulse sequence and a 70 degrees flip angle. Eight patients received 40 mg of furosemide 10 minutes before contrast material injection. RESULTS: The areas of the renal cortical and medullary signal intensity curves minus baseline in the unilateral normal kidneys were significantly greater in the group who received furosemide (P = .026 and P = .037, respectively). The areas of the renal cortical and medullary signal intensity minus baseline in the unilateral hydronephrotic kidneys were also significantly greater in the group that received furosemide (P = .036 and P = .026, respectively). There was a statistically significant increase in splenic enhancement (P = .02) and a tendency for increased liver (P = .09) and psoas muscle (P = .08) enhancement. CONCLUSION: Furosemide-induced diuresis appears to potentiate the cortical and medullary MR renogram, as well as the MR splenogram. A rapid shift in water compartmentalization from the intracellular to the extracellular space and increased renal water content with diuresis are possible explanations.

Abdomen↗

PubMed1985

Pneumococcal psoas abscess.

Primary extrapulmonary pneumococcal disease has become a rarity in modern times. We describe a 40-year-old patient who developed an abscess of the psoas muscle as the only evidence of pneumococcal disease. A predisposing local condition was prior trauma of the psoas muscle, documented by the existence of myositis ossificans circumscripta. This case emphasizes the importance of considering unusual sites of involvement of pneumococcal disease.

Abscess↗

PubMedDate not supplied

[Interpretation of the pictures of meridional diffraction on X-rays of membrane-free rabbit spinal muscles in a state of rigor and their dependence on physico-chemical parameters of rigorising solution].

Results of the studies of structural and mechanical properties of rabbit psoas muscle by means of X-ray diffraction and physiological technique are summarised along the following lines: localisation of minor proteins in the thick filaments and the origin of meridional reflections in the X-ray diffraction patterns of rigorised rabbit psoas muscle; molecular basis of the effects of pH, ionic strength, pyrophosphate, ethyleneglycol and pyrophosphate-ethyleneglycol mixture on the value of rigor tension and their dependence on the sarcomerès length and concentration of Mg2+; effect of selective extraction of minor proteins from M- and P-zones of the thick filaments on meridional reflections; structure of the thick filaments in the state of "Ca2+-free rigor"; attachment of cross-bridges to actin filaments in relaxing solution (is the model of "sterick brocking" correct?); role of structural transitions in S-2-segments of myosin in force generation.

Animals↗

PubMed1988

Staging and differential diagnosis of renal cell carcinoma: a comparison of magnetic resonance imaging (MRI) and computed tomography (CT).

The usefulness of magnetic resonance imaging (MRI) was compared with that of computed tomography (CT). Twenty-nine patients with renal cell carcinoma, 3 with angiomyolipomas and 1 with renal pelvic cancer, were examined by both MRI and CT. MRI and CT showed similar results in staging cases of renal cell carcinoma. However, MRI may be more sensitive in detecting the venous extension, metastatic adenopathy, and adjacent organ invasion. In predicting the involvement of perinephric fat, however, MRI is only marginally superior to CT. To demonstrate the usefulness of MRI in differentiating renal cell carcinoma from other renal tumors, the density of renal tumor and that of the psoas muscle were determined using a densitiometer, and the percent (%) contrast (the intensity of the renal tumor/the intensity of the psoas muscle X 100) was calculated. In most patients with clear cell type renal carcinoma, the % contrast value in the T1 weighted images was about 100. In the T2 weighted images, the maximum value of the % contrast value was 50 or less in most patients. In one patient with spindle cell type (sarcomatoid type) carcinoma, the % contrast value was 109 in the T1 weighted images, but was 65-85, at most, in the T2 weighted images. In patients with renal angiomyolipomas, the % contrast values were calculated exclusive of the fatty components. The % contrast value of the T1 weighted images was 50 or less in all 3 patients, and that of the T2 weighted images was 50 or more in 2 patients and 21-38 in the others.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1999

Psoas abscess: a 10 year review.

Psoas muscle abscesses are rarely encountered yet, and pose diagnostic and therapeutic challenges because of nonspecific clinical presentations. We retrospectively reviewed the medical records of adults with a psoas muscle abscess who were admitted to our hospital from January, 1988 to May, 1998. Over this ten year period, psoas abscesses were found in 11 cases. Six cases were primary and Staphylococcus spp. was the most commonly isolated. Five cases were a secondary psoas abscess while urological problems were the most common underlying condition. Fever, chills, lower back or flank pain and a palpable mass were the most common manifestations. Only one patient presented the classic triad of fever, flank pain, and limitation of hip movement (a typical psoas sign). Leukocytosis was the most common laboratory finding. Two of 11 cases presented septic shock. Two patients were admitted to the hospital with the initial diagnosis of psoas abscesses. Computerized tomographic (CT) scans accurately confirmed the clinical diagnosis in 9 of 11 patients. Diagnosis was then established one each by ultrasound (US) and magnetic resonance imaging (MRI), respectively. Four of 11 patients had negative findings initially by US. All patients were managed with drainage and antibiotics, nine were drained surgically, and two were managed with percutaneous drainage under CT guidance. Two patients died. Because of the lack of the classic symptoms and signs in most cases, a high degree of suspicion is important for early diagnosis of psoas abscess. CT scan is the standard technique of diagnosis. The prognosis is generally good with appropriate antibiotic treatment and complete drainage.

Adult↗