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At least 19 recordsLinked to original sources

Back extensor and psoas muscle cross-sectional area, prior physical training, and trunk muscle strength--a longitudinal study in adolescent girls.

The association between physical training, low back extensor (erector spinae plus multifidus muscles) and psoas muscle cross-sectional areas (CSA) and strength characteristics of trunk extension and flexion were studied in adolescent girls. A group of athletes (n = 49) (age range 13.7-16.3 years) consisting of gymnasts, figure skaters and ballet dancers was age-matched with non-athletes (n = 17) who acted as a sedentary control group. The CSA of psoas muscles and multifidus plus erector spinae muscles were measured from lumbar axial images by magnetic resonance imaging. Maximal trunk extension and flexion forces were measured in a standing position using a dynamometer and trunk musculature endurance was evaluated using static holding tests. When CSA were adjusted with body mass, the athletes showed significantly greater CSA in both muscles studied (psoas P < 0.001; erector spinae plus multifidus P < 0.05) than the non-athletes. The athletes also had a greater absolute psoas muscle CSA (P < 0.01) and trunk flexion force (P < 0.01) compared to the controls. When the forces were expressed relative to body mass, the athletes were superior both in trunk flexion (P < 0.001) and extension (P < 0.001). There was a significant correlation between muscle CSA and strength parameters, but the force per muscle CSA did not differ significantly between the athletes and the non-athletes. In addition, the athletes showed a better body mass adjusted muscle endurance in trunk flexion (P < 0.05) than the non-athletes. Our study indicated that regular physical training enhances trunk musculature hypertrophy, force and endurance in adolescent girls, and that there is an association between muscle CSA and strength parameters.

Adolescent↗

[Limp as a presenting symptom of psoas muscle inflammation].

Inflammatory irritation of the psoas muscle in children is rare. The initial diagnosis may be difficult because of the similarity between the symptoms of psoas muscle inflammation and septic hip joint. We present a boy and a girl, both 3.5 years old, with psoas muscle inflammation, whose initial clinical and laboratory findings could be explained by either septic hip joint or osteomyelitis. Both presented with fever and limp. 1 developed an acute abdomen within 3 days and at operation a retrocecal periappendicular abscess was found. In the other, left lower quadrant, abdominal pain developed 4 days following admission and ultrasonic findings indicated a left psoas muscle abscess. We suggest that psoas muscle inflammation should be added to the differential diagnosis of limp in children. Early correct diagnosis can be established by proper physical examination, including rectal examination, and with the aid of diagnostic tools such as ultrasound, computerized tomography or both.

Child, Preschool↗

[Primary pneumococcal abscess in the psoas muscle].

Primary psoas abscesses are rare and the pathogenesis is obscure. In most cases Staphylococcus aureus is the causative bacterium. Therapy consists of drainage of the abscess and antibiotics. In this article we present a patient with a primary psoas abscess caused by a Streptococcus pneumoniae infection.

Aged↗

[Hydatid cyst of the psoas muscle].

Hydatid cysts in the psoas muscle are unusual. The authors report a case of a hydatid cyst which had developed within the psoas muscle and was detected from a mass in the left iliac fossa which was diagnosed before surgery by ultrasound and a CT scan, which remain the preferred primary examinations for the investigation of masses of this type. The authors discuss the various possible clinical and paraclinical contexts and recommend total pericystectomy of a closed cyst as the best treatment following extraperitoneal iliac surgical opening.

Adult↗

Quantitative studies on the polarization optical properties of striated muscle. I. Birefringence changes of rabbit psoas muscle in the transition from rigor to relaxed state.

The changes in birefringence in the rigor to relax transition of single triton-extracted rabbit psoas muscle fibers have been investigated with quantitative polarized light techniques. The total birefringence of rest lenght fibers in rigor was (1.46 +/- 0.08) x 10(-3) and increased to (1.67 +/- 0.05) x 10(-3) after Mg-ATP relaxation. Pyrophosphate relaxation increased the total birefringence only slightly, whereas subsequent Mg-ATP relaxation elicited the maximum increase in birefringence. Changes in lattice spacing did not account for the total increase in birefrigence during relaxation. Moreover, the increase in total birefringence was attributable to increases in intrinsic birefringence as well as form birefringence. No change in birefringence was exhibited upon exposure to a relaxation solution after myosin extraction. Synthetic myosin filaments were prepared and treated with relaxation and rigor solutions. The negatively stained filaments treated with a rigor solution had gross irregular projections at either end, while the filaments treated with a relaxing solution were more spindle shaped. The results are compatible with the view that the subfragment-2 moieties of myosin angle away from the myosin aggregates (light meromyosin) to permit the attachment of the subfragment-1 moieties to actin.

Adenosine Triphosphate↗

Ruptured mycotic aneurysm of the iliac artery complicated by emphysematous psoas muscle abscess: report of two cases.

Emphysematous psoas muscle abscess has rarely been described and has not been reported to be associated with ruptured mycotic aneurysm. We report two cases of ruptured mycotic iliac arterial aneurysm complicated by emphysematous abscess of the left psoas muscle. Case 1 occurred in a 70-year-old man and Case 2 in a 63-year-old woman. Both patients presented with fever for several weeks. Clinical clues leading to the diagnosis included a palpable abdominal mass with (Case 2) or without (Case 1) pulsation, blurring of the psoas muscle shadow with abnormal gas distribution on the plain abdominal film (Case 1), and peripheral vascular insufficiency and Salmonella bacteremia (Case 2). Ruptured mycotic aneurysm of the left iliac artery complicated with left psoas muscle abscess was clearly demonstrated by abdominal computerized tomography scan and intravenous digital subtraction angiography in both cases. Causative agents, multi-drug resistant Acinetobacter baumannii and Klebsiella pneumoniae, unusual pathogens for mycotic arterial aneurysm, were cultured from debrided tissue in Case 1, and this finding led to the speculation that the infection was hospital-acquired. The favorable outcome in Case 2 resulted from early vascular surgery and a prolonged course of effective antimicrobial therapy.

Aged↗

[Colonic interposition between kidney and psoas muscle: anatomical variation studied with CT].

Interposition of the colon between kidney and psoas muscle may represent a benign anatomical variant that can be recognized on Computed Tomography (CT) images. In our series including 428 abdominal CT examinations, the position of the bowel in the pararenal space was studied with respect to the kidney and the psoas muscle. To determine the colon position in the pararenal space, three CT scans, at the upper pole, midkidney and lower pole, for each side, were selected. The colonic interposition between the kidney and the psoas muscle was then correlated with patient's age, sex and amount of perinephric fat. The ascending colon was interposed between the kidney and the psoas muscle in 6/428 cases (1.4%), appearing more frequently in adult men. Of these 6 cases, CT showed decreased perinephric fat in three cases, normal in one and increased in two. No case of descending colonic interposition between the kidney and the psoas muscle was demonstrated. CT is a valuable tool to depict this anatomical variation, preventing misdiagnoses and complications arising from interventional procedures.

Adult↗

Adenocarcinoma of the lung metastatic to the psoas muscle.

Hematogenous metastasis to the psoas muscle is rare, and the resulting clinical symptoms may mimic psoas abscess or hemorrhage. When the clinical history is not specific, CT is important in documenting the presence of a psoas mass and providing biopsy guidance for histologic diagnosis. Only three previously reported cases have been related to a primary carcinoma of the lung.

Adenocarcinoma↗

[Retroperitoneal hematoma secondary to traumatic rupture of the psoas muscle].

Rupturing of the psoas muscle by closed injury as a result of the formation of a retroperitoneal hematoma is a very uncommon pathological entity, which may rise problems of differential diagnosis with kidney lesions. Supplementary explorations do not always clear up diagnostic doubts, and it is surgery, if indicated, that confirms the picture. We present a case of retroperitoneal hematoma of traumatic origin in a one-kidney ipsilateral patient, in whom the abdominal CAT revealed affection of the renal capsule associated with rupture of teh psoas. In the surgery carried out due to formation of an abscess in the hematoma we verified that the kidney was undamaged.

Adult↗

Solitary benign schwannoma in the psoas muscle.

Solitary benign schwannoma in the psoas muscle is extremely rare. Here we present a case report of a woman who had solitary benign schwannoma in the psoas muscle not associated with von Recklinghausen's disease. This is the fifth case reported in the literature.

Adult↗

Psoas muscle disorders: MR imaging.

Nineteen patients with evidence of psoas and iliopsoas abnormalities on computed tomographic (CT) scans (12 with metastases, three with lymphoma, two with hematoma, and two with abscess) were examined with magnetic resonance (MR) imaging. The abnormal psoas could be identified on both T1- and T2-weighted spin-echo images, although T2-weighted sequences provided better contrast. The psoas muscle can be affected by one of three mechanisms: total replacement, lateral displacement, or medial displacement. In four patients in whom the CT study showed apparent enlargement of a psoas muscle, subsequent MR imaging examinations demonstrated that the psoas muscle was compressed and displaced laterally by a paraspinal mass. MR images provided better contrast between the normal and abnormal psoas than CT scans in nine cases; MR images were inferior to CT scans in two cases because calcifications (one case) and air bubbles within an abscess (one case) were not detectable.

Abscess↗

Computed tomography of ilio-psoas muscle tumors.

A retrospective evaluation of computed tomographic scans done at our institution showing psoas muscle tumors is presented. The anatomy of the psoas muscle along with a discussion of normal psoas anatomy which can be mistaken for tumor are reviewed. Primary muscle tumors along with metastatic, neurogenic, and lymphomatous tumors affecting the psoas muscle is discussed. The use of computed tomography for assessment of extent, origin, and structure of psoas muscle tumors is demonstrated.

Adult↗

The ultrasound appearance of the normal psoas muscle.

One hundred and forty-four psoas muscles in 72 subjects were scanned to study the normal ultrasound appearance. For the purpose of description the psoas was divided into three sections. Ten of the 432 sections could not be adequately seen on ultrasound. The psoas demonstrated hyperechoic striations on a hypoechoic background typical of muscle. In addition the upper section, from the origin of the muscle to the lower pole of the kidney, contained echogenic planes in 15 (10%) and the mid section, from the lower pole of kidney to iliac crest, demonstrated prominent echogenic planes and focal areas of increased and decreased echogenicity in 65 (46%). The lower section, from the iliac crest to fusion with the iliacus, demonstrated a single echogenic plane in 96 (70.5%) which was best seen running obliquely in the transverse plane and in 40 (29.5%) there were more complex echogenic planes or focal areas of increased or decreased echogenicity. The cause of the prominent echogenic plane in the lower section was not apparent in the anatomical literature and therefore cadaveric dissection of nine psoas muscles was performed which demonstrated that the echogenic plane was caused by intramuscular tendon fibres formed from the more cranial origins of the psoas. The psoas minor was not identified as a separate structure.

Adolescent↗

Cross-bridge binding to actin and force generation in skinned fibers of the rabbit psoas muscle in the presence of antibody fragments against the N-terminus of actin.

To assess the significance of the NH2-terminus of actin for cross-bridge action in muscle, skinned fibers of rabbit psoas muscle were equilibrated with Fab fragments of antibodies directed against the first seven N-terminal residues of actin. With the antibody fragment, active force is more inhibited than relaxed fiber stiffness, or stiffness in rigor or in the presence of magnesium pyrophosphate. Inhibition of stiffness in rigor or with magnesium pyrophosphate does not necessarily indicate involvement of the NH2-terminus of actin in strong cross bridge binding to actin but may simply result from the large size of the Fab. At high Fab concentrations, active force is essentially abolished, whereas stiffness is still detectible under all conditions. Thus, complete inhibition of active force apparently is not due to interference with cross-bridge binding to actin but may result from the Fab-mimicking inhibition of the thin filament by Troponin-1 binding to the NH2-terminus of actin at low Ca2+. However, although Troponin-1 is released from the NH2-terminus at high Ca2+, the Fab is not, thus disallowing force generation upon increase in Ca2+. These data are consistent with involvement of the NH2-terminus of actin in both weak cross-bridge binding to actin and Ca2+ regulation of the thin filament.

Actins↗

Polyneural innervation in the psoas muscle of the developing rat.

Polyneural innervation was studied in the psoas muscle in developing rats from P4 till P25 and at adult age, with the combined silver-acetylcholinesterase technique. Nerve endings were counted, and end-plates were measured. These data were compared with such data in the human. The end of polyneural innervation in the rat (around P20) and in the human (around 12 weeks postterm age) in both cases coincides with a transformation in motor behavior and postural control. The rat's psoas muscle at early stages is less heavily innervated than this muscle in the human. Up to three axons per motor end-plate were counted at P4, but in the human up to five axons at 25 weeks of post menstrual age. This difference might be related to the lower percentage of type I muscle fibers in the rat.

Animals↗

Temperature-induced structural changes in the myosin thick filament of skinned rabbit psoas muscle.

By using synchrotron radiation and an imaging plate for recording diffraction patterns, we have obtained high-resolution x-ray patterns from relaxed rabbit psoas muscle at temperatures ranging from 1 degree C to 30 degrees C. This allowed us to obtain intensity profiles of the first six myosin layer lines and apply a model-building approach for structural analysis. At temperatures 20 degrees C and higher, the layer lines are sharp with clearly defined maxima. Modeling based on the data obtained at 20 degrees C reveals that the average center of the cross-bridges is at 135 A from the center of the thick filament and both of the myosin heads appear to wrap around the backbone. At 10 degrees C and lower, the layer lines become very weak and diffuse scattering increases considerably. At 4 degrees C, the peak of the first layer line shifts toward the meridian from 0.0047 to 0.0038 A(-1) and decreases in intensity approximately by a factor of four compared to that at 20 degrees C, although the intensities of higher-order layer lines remain approximately 10-15% of the first layer line. Our modeling suggests that as the temperature is lowered from 20 degrees C to 4 degrees C the center of cross-bridges extends radially away from the center of the filament (135 A to 175 A). Furthermore, the fraction of helically ordered cross-bridges decreases at least by a factor of two, while the isotropic disorder (the temperature factor) remains approximately unchanged. Our results on the order/disordering effects of temperature are in general agreement with earlier results of Wray [Wray, J. 1987. Structure of relaxed myosin filaments in relation to nucleotide state in vertebrate skeletal muscle. J. Muscle Res. Cell Motil. 8:62a (Abstr.)] and Lowy et al. (Lowy, J., D. Popp, and A. A. Stewart. 1991. X-ray studies of order-disorder transitions in the myosin heads of skinned rabbit psoas muscles. Biophys. J. 60:812-824). and support Poulsen and Lowy's hypothesis of coexistence of ordered and disordered cross-bridge populations in muscle (Poulsen, F. R., and J. Lowy. 1983. Small angle scattering from myosin heads in relaxed and rigor frog skeletal muscle. Nature (Lond.). 303:146-152.). However, our results added new insights into the disordered population. Present modeling together with data analysis (Xu, S., S. Malinchik, Th. Kraft, B. Brenner, and L. C. Yu. 1997. X-ray diffraction studies of cross-bridges weakly bound to actin in relaxed skinned fibers of rabbit psoas muscle. Biophys. J. 73:000-000) indicate that in a relaxed muscle, cross-bridges are distributed in three populations: those that are ordered on the thick filament helix and those that are disordered; and within the disordered population, some cross-bridges are detached and some are weakly attached to actin. One critical conclusion of the present study is that the apparent order <--> disorder transition as a function of temperature is not due to an increase/decrease in thermal motion (temperature factor) for the entire population, but a redistribution of cross-bridges among the three populations. Changing the temperature leads to a change in the fraction of cross-bridges located on the helix, while changing the ionic strength at a given temperature affects the disordered population leading to a change in the relative fraction of cross-bridges detached from and weakly attached to actin. Since the redistribution is reversible, we suggest that there is an equilibrium among the three populations of cross-bridges.

Actin Cytoskeleton↗

[The structure of thick filaments on longitudinal sections of rabbit psoas muscle].

By means of electron microscopy the longitudinal sections of chemically skinned fibres of rigorised rabbit psoas muscle have been examined at pH of rigorising solutions equal to 6, 7, 8 (I = 0.125) and ionic strengths equal to 0.04, 0.125, 0.34 (pH 7.0). It has been revealed that at pH 6.0 the bands of minor proteins localization in A-disks were seen very distinctly, while at pH 7.0 and I = 0.125 these bands can be revealed only by means of antibody labelling technique. At the ionic strength of 0.34 (pH 7.0) the periodicity of 14.3 nm in thick filaments was clearly observed, which was determined by packing of the myosin rods into the filament shaft and of the myosin heads (cross-bridges) on the filament surface. The number of cross-bridge rows in the filament equals 102. A new scheme of myosin cross-bridge distribution in thick filaments of rabbit psoas muscle has been suggested according to which two rows of cross-bridges at each end of a thick filament are absent. The filament length equals 1.64 +/- 0.01 micron. It has been shown that the length of thick filament as well as the structural organization of their end regions in rabbit psoas muscle and frog sartorius one are different.

Animals↗

Effects of ionic strength on force transients induced by flash photolysis of caged ATP in covalently crosslinked rabbit psoas muscle fibers.

Single fibers from glycerinated rabbit psoas muscle were treated with 1-ethyl-3[3-(dimethylamino) propyl] carbodiimide (EDC), after rigor was induced, to crosslink myosin heads to actin. The optimally pre-stretched (approximately 1.8%), partially crosslinked fibers produce a large force when MgATP is depleted, and this force is abolished when MgATP is reintroduced, even in high ionic strength solution of 0.5 M (Tawada et al. 1989). We investigated the rate of force decay in the crosslinked, force-producing fibers using pulse photolysis of caged ATP (Goldman et al. 1984). The decay of force was fast, the rate of which depending both on the ionic strength and on the amount of ATP released (0.2-2.2 mM) with the second-order rate constant of 0.5-1 x 10(5) M-1s-1 at the ionic strength of 0.5 M. At high ionic strength (1-2M) force decayed at lower rate. At low ionic strength (0.1-0.2 M), however, force decayed more rapidly, but force redeveloped subsequently, which is probably caused by uncrosslinked myosin heads.

Adenosine Triphosphate↗