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PubMedDate not supplied

[X-ray study of pH-dependence of thick filament structure in stripped fiber bundles of vertebrate skeletal muscles].

Molecular origin of pH-dependence of rigor tension in chemically skinned fibre bundles of rabbit psoas muscle was studied with the help of X-ray diffraction technique. It was found that a shift of pH from the neutral value of about 7.0 either to basic or to acidic regions by one unit is accompanied by changes of relative intensities in a number of meridional reflections. These effects are explained as the result of pH-induced detachment of subfragments-2 of myosin molecules from the thick filament surface. The data obtained indicate that force generation in muscle may be caused by the structural changes of subfragments-2 of myosin molecules.

Animals↗

PubMed1985

[Iliopsoas hemorrhage in hemophilic children].

Sixty-nine children with hemophilia were treated in our center between 1968 and 1983. About 1 per cent of hemorrhagic complications were bleedings localized in the iliopsoas muscle of 12 patients ranging in age from 9 to 15 years. The typical sign of the bleeding is a tight, palpable tumour above the inguinal fold. Today mass bleedings of the muscle with retroperitoneal localization are diagnosed safely by help of computer tomography or sonography. Psoas muscle bleedings in children are characterized by a high recurrence rate (41.5%) and often by an associated damage of the femoral nerve. Surgery was necessary only in 1 patient where a huge psoas hematoma with cystic transformations had to be removed. High substitution doses led to a complete recovery within 3 weeks in all other children.

Adolescent↗

PubMed2002

Structural features of cross-bridges in isometrically contracting skeletal muscle.

Two-dimensional x-ray diffraction was used to investigate structural features of cross-bridges that generate force in isometrically contracting skeletal muscle. Diffraction patterns were recorded from arrays of single, chemically skinned rabbit psoas muscle fibers during isometric force generation, under relaxation, and in rigor. In isometric contraction, a rather prominent intensification of the actin layer lines at 5.9 and 5.1 nm and of the first actin layer line at 37 nm was found compared with those under relaxing conditions. Surprisingly, during isometric contraction, the intensity profile of the 5.9-nm actin layer line was shifted toward the meridian, but the resulting intensity profile was different from that observed in rigor. We particularly addressed the question whether the differences seen between rigor and active contraction might be due to a rigor-like configuration of both myosin heads in the absence of nucleotide (rigor), whereas during active contraction only one head of each myosin molecule is in a rigor-like configuration and the second head is weakly bound. To investigate this question, we created different mixtures of weak binding myosin heads and rigor-like actomyosin complexes by titrating MgATPgammaS at saturating [Ca2+] into arrays of single muscle fibers. The resulting diffraction patterns were different in several respects from patterns recorded under isometric contraction, particularly in the intensity distribution along the 5.9-nm actin layer line. This result indicates that cross-bridges present during isometric force generation are not simply a mixture of weakly bound and single-headed rigor-like complexes but are rather distinctly different from the rigor-like cross-bridge. Experiments with myosin-S1 and truncated S1 (motor domain) support the idea that for a force generating cross-bridge, disorder due to elastic distortion might involve a larger part of the myosin head than for a nucleotide free, rigor cross-bridge.

Actins↗

PubMedDate not supplied

[Diagnosis and therapy of psoas abscess].

PROBLEM: Psoas abscesses are really rare so that the diagnostic onset is commonly very late. The differential diagnosis to other retroperitoneal processes is therefore important. METHOD: In a period of observation of 6 years 21 patient were treated with psoas abscesses. The evaluation of 16 records was done retrospectively under consideration of etiology, history, clinical examination, lab results and x-ray/CT/MRI etc. RESULTS: With the knowledge of the anatomy of the ilio-psoas muscle the clinical examination gives us important information about the diagnosis of psoas abscess. The history and the clinical examination precede the further diagnostics and are condition for high rates of sensitivity and specificity. Lab results indicate an absedation without being specific. The exclusive position of radiological diagnostics is undisputed. Ultrasound, x-ray and leucocyte marked bonescan are proven to be helpful in cases of unknown location of the abscesses. Method of choice seems to be the contrast enhanced CT-scan. The differential diagnosis includes gastrointestinal or renal disorders as well as pathology of bone or joints. In our cases differential diagnosis was complicated since the diagnostic onset was delayed and the initial therapy was not adequate. The diagnosis "abscess of the psoas" does not imply a general regime for therapy therefore an individual treatment in consideration of percutaneous and operative drainage has to be recommended. In selected cases a combination therapy is advised. CONCLUSION: In every case of retroperitoneal symptoms the differential diagnosis of an abscess of the psoas has to be regarded. The diagnosis is subtil and requires clinical and laboratory examinations as well as contrast enhanced computerscan. The therapy follows operative measures. The technique has to be individually decided.

Adult↗

PubMed1991

Optical diffraction by well-ordered muscle fibres.

We have studied the diffraction of a focussed laser beam by single fibres of glycerinated rabbit psoas muscle as a function of the angle of incidence. Diffraction efficiencies as high as 34% were observed at the first-order Bragg angle, indicative of well-ordered striated fibres with a strong periodic modulation of the refractive index. A theory is presented to account for our observations based upon the coupled-wave model developed by Kogelnik (1967) and Magnusson and Gaylord (1977) for the description of thick phase gratings in holography. We have solved the coupled-wave equations on a computer using a realistic index modulation taken from the measurements of Huxley and Hanson (1957). Comparison of theory with experiment shows that coupled-wave effects are indeed present in well-ordered muscle fibres, and the observed diffraction efficiency is in quite good agreement with what would be expected theoretically. Most importantly, the computer model allows us to calculate the diffraction efficiency for curved striations, which are observed for real muscle fibres under a microscope. The sensitivity of the diffraction efficiency to curvature of the striations may have implications for the interpretation of other optical experiments on muscle. We also consider the effects on our measurements of the focussing lens and refraction by the cylindrical fibre.

Animals↗

PubMed1984

Contraction of rabbit skinned skeletal muscle fibers at low levels of magnesium adenosine triphosphate.

The contractile properties of skinned single fibers from rabbit psoas muscle were investigated under conditions of low MgATP and no Ca2+ (i.e., less than 10(-8) M). At 1 microM MgATP, fibers shortened at a maximum velocity of 660 +/- 420 A/half sarcomere/s (n = 9), compared with 34,000 A/half sarcomere/s measured during maximum Ca2+-activation at 1 mM MgATP (Moss, R. L., 1982. J. Muscle Res. Cell. Motil ., 3:295-311). The observed dependence of Vmax on pMgATP between 7.0 and 5.3 was similar to that of actomyosin ATPase measured previously by Weber, A., R. Herz , and I. Reiss (1969, Biochemistry, 8:2266-2270). Isometric tension was found to vary with pMgATP in a manner much like that reported by Reuben , J. P., P. W. Brandt, M. Berman , and H. Grundfest (J. Gen. Physiol. 1971. 57:385-407). A simple cross-bridge model was developed to simulate contractile behaviour at both high and low levels of MgATP. It was found that the pMgATP dependence of Vmax and ATPase could be successfully modeled if the rate of detachment of the cross-bridge was made proportional to the concentration of MgATP. In the model, the similar dependence of Vmax and ATPase on pMgATP was derived from the fact that in this range of pMgATP every pass of a cross-bridge by an actin site resulted in an attachment-detachment cycle, and every such cycle caused hydrolysis of one molecule of ATP.

Adenosine Triphosphatases↗

PubMed1994

Thermal stress and Ca-independent contractile activation in mammalian skeletal muscle fibers at high temperatures.

Temperature dependence of the isometric tension was examined in chemically skinned, glycerinated, rabbit Psoas, muscle fibers immersed in relaxing solution (pH approximately 7.1 at 20 degrees C, pCa approximately 8, ionic strength 200 mM); the average rate of heating/cooling was 0.5-1 degree C/s. The resting tension increased reversibly with temperature (5-42 degrees C); the tension increase was slight in warming to approximately 25 degrees C (a linear thermal contraction, -alpha, of approximately 0.1%/degree C) but became more pronounced above approximately 30 degrees C (similar behavior was seen in intact rat muscle fibers). The extra tension rise at the high temperatures was depressed in acidic pH and in the presence of 10 mM inorganic phosphate; it was absent in rigor fibers in which the tension decreased with heating (a linear thermal expansion, alpha, of approximately 4 x 10(-5)/degree C). Below approximately 20 degrees C, the tension response after a approximately 1% length increase (complete < 0.5 ms) consisted of a fast decay (approximately 150.s-1 at 20 degrees C) and a slow decay (approximately 10.s-1) of tension. The rate of fast decay increased with temperature (Q10 approximately 2.4); at 35-40 degrees C, it was approximately 800.s-1, and it was followed by a delayed tension rise (stretch-activation) at 30-40.s-1. The linear rise of passive tension in warming to approximately 25 degrees C may be due to increase of thermal stress in titin (connectin)-myosin composite filament, whereas the extra tension above approximately 30 degrees C may arise from cycling cross-bridges; based on previous findings from regulated actomyosin in solution (Fuchs, 1975), it is suggested that heating reversibly inactivates the troponin-tropomyosin control mechanism and leads to Ca-independent thin filament activation at high temperatures. Additionally, we propose that the heating-induced increase of endo-sarcomeric stress within titin-myosin composite filament makes the cross-bridge mechanism stretch-sensitive at high temperatures.

Animals↗

PubMed1991

Tension responses to rapid pressure release in glycerinated rabbit muscle fibers.

We have previously shown that the isometric tension of a fully calcium-activated skinned rabbit psoas muscle fiber is reversibly depressed by increased hydrostatic pressure. We report here the characterization of tension transients induced by a rapid (less than 1-ms) release of increased pressure at 12 degrees C. The tension transient consists of three clear phases, an initial further decrease of tension in phase with pressure change followed by two phases of tension increase back to the level recorded at ambient pressure. The mean reciprocal relaxation time for phase 2 (1/tau 2) was approximately 17 s-1 and that for phase 3 (1/tau 3) was 3 s-1. The presence of 20 mM inorganic phosphate markedly increased 1/tau 2 to approximately 52 s-1 and decreased 1/tau 3 to approximately 1.7 s-1. These observations are interpreted in terms of a pressure-sensitive transition between two attached crossbridge states of low (or zero) and higher force. This is compatible with the pressure-sensitive isomerization of actomyosin previously observed in solution. The results presented allow us to propose a coupling between a specific pressure-sensitive isomerization of purified actomyosin, the phosphate release step of the ATPase pathway, and the force-generating event of the cross-bridge cycle.

Animals↗

PubMed2006

Viscosity as an inseparable partner of muscle contraction.

A simple model is presented where, by an iterative procedure, the forces delivered by the power strokes are summed up to overcome the load. The system is moderated by the viscous hindrance. The model reproduces the features of muscle contraction as defined by the data of He et al. [1997. ATPase kinetics on activation of permeabilized isometric fibres from rabbit and frog muscle: a real time phosphate assay. J. Physiol. 501, 125-148] on rabbit psoas muscle fibres. According to the model power strokes are random. Energy summation take place if the subsequent power stroke occurs before the energy delivered by the previous power stroke is completely used. In order the sarcomere to be competent to contract initial driving force must reach a threshold whose value increases with the load. The step size of the power stroke decreases with the increase of the load. The viscous regime is simulated by the equation, where 1/k measures the viscous hindrance of the system. The relationship between water activity, viscosity and stiffness is discussed. It is concluded that the three parameters vary cyclically and that when water activity decreases (sarcomere shortening, cross-bridge attachment) viscosity and stiffness increase.

Animals↗

PubMed1988

Thick filaments of striated muscle are laterally interconnected.

Earlier reports from this and other laboratories indicated that thick filaments may be interconnected along their length by rung-like structures. This study was carried out to test whether these interconnections are genuine structures; whether they appear in different muscle types; and whether they arise from myosin cross-bridges. We studied insect flight muscles because of their well-known ultrastructure, and frog heart and rabbit psoas muscles secondarily. Ultrastructure was examined with freeze-fracture; with conventionally prepared thin sections; and with negative stain. All three methods showed rung-like interconnections between thick filaments. The interconnections spanned the length of the cross-bridge zone, i.e., along all but the central bare zone of the thick filament. They were observed consistently in relaxed, activated, and rigor states. We considered potential artifacts that might cause apparent interconnections where none existed in vivo, but were unable to identify a source of artifact common to all methods. Several features of the interconnections imply that for the most part they may be composed of S-1 heads from adjacent thick filaments binding to one another at their tips.

Animals↗

PubMed1970

The Meyerhof quotient and the synthesis of glycogen from lactate in frog and rabbit muscle.

1. The conversion of lactate into glycogen was demonstrated in frog sartorius muscle in oxygen. The rates and amounts are highest when lactate is added to the bathing medium and are dependent on lactate and CO(2) concentration, as well as pH. The glycogen content of a resting muscle can be doubled in 4h at 24 degrees C. 2. Sartorius muscle, recovering aerobically in liquid paraffin from a period of anoxia, converts preformed lactate into glycogen at a lower rate and in smaller amounts than when lactate is added in an aqueous medium. The lower rates are similar to those Meyerhof found under the same conditions, after correction for temperature; they can be attributed partly to low muscle pH and partly to the limited amounts of lactate present. 3. Rabbit psoas muscle also shows the ability to convert added lactate into glycogen under aerobic conditions. The rates are low and similar to those in frog sartorius muscle recovering from anoxia. 4. The present experiments yield a Meyerhof quotient of 6.2, compared with Meyerhof's value of 4-5. However, these values are not significantly different from one another. 5. It is suggested that the glycogen coefficient, i.e. mol of glycogen formed/mol of lactate disappearing, is a more reliable way of assessing the resynthetic mechanism than the original quotient, i.e. mol of lactate disappearing/mol of lactate oxidized. The found coefficient is 0.419+/-0.024.

Animals↗

PubMed2003

The Anterolateral TransPsoatic Approach (ALPA): a new technique for implanting prosthetic disc-nucleus devices.

Prosthetic disc-nucleus devices have traditionally been implanted via the same posterior approach that is standard for lumbar decompression surgery. To avoid disrupting the posterior structures of the spine and to facilitate device implantation, the AnteroLateral transPsoatic Approach (ALPA) has been developed. With ALPA, an incision is made in the lateral region overlying the disc, and the lateroabdominal muscles are bluntly dissected. The retroperitoneal area is accessed and followed to the psoas muscle, where blunt dissection in the direction of the muscle fibers is used to reach the affected disc. The disc anulus is cut to create a flap, the nucleus pulposus material is removed, and the prosthesis is implanted into the disc cavity. The procedure concludes with the anulus flap being sutured in place over the opening to the nucleus, and the wound is closed in a normal manner. A small study group of eight patients has been implanted with PDN prosthetic disc-nucleus devices by way of the ALPA technique. Preliminary results indicate minor adverse events related to the surgical technique. Clinical results are also encouraging with significant improvements in Oswestry and Prolo scores and with an associated increase in disc height. The ALPA technique is a good alternative to the posterior hemilaminotomy approach for implanting nucleus devices in degenerated lumbar discs.

Arthroplasty, Replacement↗

PubMed2005

Primary brucellar psoas abscess: presentation of a rare case of psoas abscess caused by Brucella melitensis without any osteoarticular involvement.

The psoas abscess is an entity, sometimes forgotten in our daily practice, because of infrequency and difficulties in diagnosis. Primary psoas abscess is very rare and gram-positive micro-organisms account for more than 80% of the cases. Our case, a 62-year-old man was admitted with a 5-year history of back pain and fever. Physical examination was normal, except a palpable hepatomegaly with a mild tenderness over his lower right abdominal quadrant. The Brucella agglutination test was strongly positive with a titre of 1/640, as Rose Bengal Spot test. Blood cultures for brucella were positive on the fourth day and became negative, as the specific therapy started. Further examination with ultrasonography and computed tomography revealed an abscess of 40 + 75 mm in the psoas muscle. Complete resolution of symptoms achieved within 6 weeks. Although clinical presentation of psoas abscesses is often similar and non-specific, early aetiological diagnosis is extremely important, because of high achievement with appropriate antibiotic regimens. Brucellar psoas abscess seems very rare even in Turkey, where Brucella is still highly endemic. Such a case has not been previously reported from Turkey, as far as we know.

Brucella melitensis↗

PubMed1988

Mechanism of anthraquinone-induced calcium release from skeletal muscle sarcoplasmic reticulum.

The anthraquinones, doxorubicin, mitoxantrone, daunorubicin and rubidazone are shown to be potent stimulators of Ca2+ release from skeletal muscle sarcoplasmic reticulum (SR) vesicles and to trigger transient contractions in chemically skinned psoas muscle fibers. These effects of anthraquinones are the direct consequence of their specific interaction with the [3H] ryanodine receptor complex, which constitutes the Ca2+ release channel from the triadic junction. In the presence of adenine nucleotides and physiological Mg2+ concentrations (approximately 1.0 mM), channel activation by doxorubicin and daunorubicin exhibits a sharp dependence on submicromolar Ca2+ which is accompanied by a selective, dose-dependent increase in the apparent affinity of the ryanodine binding sites for Ca2+, in a manner similar to that previously reported with caffeine. Unlike caffeine, however, anthraquinones increase [3H]ryanodine receptor occupancy to the level observed in the presence of adenine nucleotides. A strong interaction between the anthraquinone and the caffeine binding sites on the Ca2+ release channel is also observed when monitoring Ca2+ fluxes across the SR. Millimolar caffeine both inhibits anthraquinone-stimulated Ca2+ release, and reduces anthraquinone-stimulated [3H]ryanodine receptor occupancy, without changing the effective binding constant of the anthraquinone for its binding site. The degree of cooperativity for daunorubicin activation of Ca2+ release from SR also increases in the presence of caffeine. These results demonstrate that the mechanism by which anthraquinones stimulate Ca2+ release is caused by a direct interaction with the [3H]ryanodine receptor complex, and by sensitization of the Ca2+ activator site for Ca2+.

Adenosine Triphosphate↗

PubMed2007

Muscle length and lengthening velocity in voluntary crouch gait.

The purpose of this study was to explore how origin-insertion length and lengthening velocity of hamstring and psoas muscle change as a result of crouch gait. The second purpose was to study the effect of changes in walking speed, in crouch, on muscle lengths and velocities. Eight healthy female subjects walked on a treadmill both normally and in crouch. In the crouch condition, subjects walked at three different walking speeds. 3D kinematic data were collected and muscle lengths and velocities were calculated using musculoskeletal modeling. It was found that voluntary walking in crouch resulted in shorter psoas length compared to normal, but not in shorter hamstrings length. Moreover, crouch gait did not result in slower muscle lengthening velocities compared to normal gait. These results do not support the role of hamstrings shortness or spasticity in causing crouch gait. Decreasing walking speed clearly reduced muscle lengths and lengthening velocities. Therefore, patients with short or spastic muscles are more likely to respond by walking slower than by walking in crouch. Also, differences in walking speed should be avoided as a confounding factor when comparing patient groups with controls.

Adult↗

PubMed2000

Measurement of nucleotide exchange rate constants in single rabbit soleus myofibrils during shortening and lengthening using a fluorescent ATP analog.

The kinetics of displacement of a fluorescent nucleotide, 2'(3')-O-[N[2-[[Cy3]amido]ethyl]carbamoyl]-adenosine 5'-triphosphate (Cy3-EDA-ATP), bound to rabbit soleus muscle myofibrils were studied using flash photolysis of caged ATP. Use of myofibrils from this slow twitch muscle allowed better resolution of the kinetics of nucleotide exchange than previous studies with psoas muscle myofibrils (, Biophys. J. 73:2033-2042). Soleus myofibrils in the presence of Cy3-EDA-nucleotides (Cy3-EDA-ATP or Cy3-EDA-ADP) showed selective fluorescence staining of the A-band. The K(m) for Cy3-EDA-ATP and the K(d) for Cy3-EDA-ADP binding to the myofibril A-band were 1.9 microM and 3.8 microM, respectively, indicating stronger binding of nucleotide to soleus cross-bridges compared to psoas cross-bridges (2.6 microM and 50 microM, respectively). After flash photolysis of caged ATP, the A-band fluorescence of the myofibril in the Cy3-EDA-ATP solution under isometric conditions decayed exponentially with a rate constant of 0.045 +/- 0.007 s(-1) (n = 32) at 10 degrees C, which was about seven times slower than that for psoas myofibrils. When a myofibril was allowed to shorten with a constant velocity, the nucleotide displacement rate constant increased from 0.066 s(-1) (isometric) to 0.14 s(-1) at 20 degrees C with increasing shortening velocity up to 0.1 myofibril length/s (V(max), the shortening velocity under no load was approximately 0. 2 myofibril lengths/s). The rate constant was not significantly affected by an isovelocity stretch of up to 0.1 myofibril lengths/s. These results suggest that the cross-bridge kinetics are not significantly affected at higher strain during lengthening but depend on the lower strain during shortening. These data also indicate that the interaction distance between a cross-bridge and the actin filament is at least 16 nm for a single cycle of the ATPase.

Adenosine Triphosphate↗

PubMed1987

The immunohistochemical location of cathepsin L in rabbit skeletal muscle. Evidence for a fibre type dependent distribution.

The immunohistochemical location of cathepsin L in rabbit soleus, plantaris and psoas muscles was investigated using the peroxidase-anti-peroxidase (PAP) technique. The amount of enzyme detected varied according to the fibre type, which were identified by histochemical staining of serial sections for succinate dehydrogenase and alkali-stable myosin ATPase. In the three muscles studied labelling was strongest in the highly oxidative fibres and weaker in the other fibre types with least staining in the fast white fibres. Immunoreactive cathepsin L appeared to be most concentrated at the periphery of muscle fibres, especially near to the nuclei, although some staining was seen throughout the fibres.

Adenosine Triphosphatases↗

PubMed1989

Alpha-actinin is a component of the Z-filament, a structural backbone of skeletal muscle Z-disks.

The relationship between the ultrastructure and protein components of Z-disks was studied using psoas muscles of rabbit and breast muscles of chicken. Glycerinated fiber bundles of these muscles were treated with a solution containing 0.1 mM Ca2+ to induce a structural weakening of Z-disks non-enzymatically. During the treatment, clear geometrical configurations of Z-filaments could be observed along with removal of amorphous matrix under an electron microscope. Even after a prolonged treatment for 14 d in which all Z-disks were entirely weakened, entangled Z-filaments were left in the original region of the disks. Immunoelectron microscopic observations showed that antibodies against alpha-actinin bound to the entangled Z-filaments, forming dense lines at the position of the original Z-disks. On SDS-PAGE of Z-disk substances, alpha-actinin remained unchanged and Mr 75,000 and 55,000 proteins were removed during the Ca2+-treatment. We therefore conclude that alpha-actinin is a component of Z-filaments, and that the amorphous matrix is composed at least of these Mr 75,000 and 55,000 proteins.

Actinin↗