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Fate of the psoas muscle after open reduction for developmental dislocation of the hip (DDH).

We evaluated the anatomic and functional consequences of psoas lengthening during operative intervention for developmental dislocation of the hip (DDH). Possible anatomic changes were assessed by magnetic resonance imaging (MRI), and functional assessment included strength determination by an isokinetic dynamometer and gait analysis. Six girls and one boy, ranging in age from 15 to 20 months, had operative reduction of a unilateral DDH. One closed and six open reductions (three anteromedial and three anterolateral approaches) were performed. Follow-up ranged from 4 years 0 months to 9 years 2 months. The cross-sectional area determined by MRI of the lengthened psoas muscles was markedly reduced for all of the six open-reduction patients (three moderate and three severe). Atrophy of the iliacus muscle also was apparent by MRI in five of the six open-reduction patients. Maximum flexion torque, as determined by the isokinetic dynamometer, was diminished on the DDH side for the three patients whose hips were reduced open through the anteromedial approach. Average hip-flexion torque over the entire range of motion was decreased for both anteromedial and anterolateral groups on the operated-on side. Lengthening of the psoas tendon during open reduction of a DDH is associated with considerable atrophy of the psoas muscle.

Atrophy↗

Interposition of the colon between the kidney and the psoas muscle: a normal anatomic variation studied by CT.

The position of the bowel in the pararenal space was examined in relation to the kidney and the psoas muscle in 1203 abdominal computed tomographic (CT) examinations. The ascending colon was found between the lower kidney pole and the psoas muscle in 1.7% and the descending colon in 0.7% of the patients. This variation appeared more frequently in women, young adults, and individuals with less intrabdominal fat. Lateral displacement of the lower kidney pole was observed in 40% of the patients with this normal variation. These findings may be of value when interpreting urographic and abdominal CT examinations.

Adult↗

X-ray diffraction studies of cross-bridges weakly bound to actin in relaxed skinned fibers of rabbit psoas muscle.

X-ray diffraction patterns were obtained from skinned rabbit psoas muscle under relaxing and rigor conditions over a wide range of ionic strengths (50-170 mM) and temperatures (1 degree C-30 degrees C). For the first time, an intensification of the first actin-based layer line is observed in the relaxed muscle. The intensification, which increases with decreasing ionic strength at various temperatures, including 30 degrees C, parallels the formation of weakly attached cross-bridges in the relaxed muscle. However, the overall intensities of the actin-based layer lines are low. Furthermore, the level of diffuse scattering, presumably a measure of disorder among the cross-bridges, is little affected by changing ionic strength at a given temperature. The results suggest that the intensification of the first actin layer line is most likely due to the cross-bridges weakly bound to actin, and that the orientations of the weakly attached cross-bridges are hardly distinguishable from the detached cross-bridges. This suggests that the orientations of the weakly attached cross-bridges are not precisely defined with respect to the actin helix, i.e., nonstereospecific. Intensities of the myosin-based layer lines are only marginally affected by changing ionic strength, but markedly by temperature. The results could be explained if in a relaxed muscle the cross-bridges are distributed between a helically ordered and a disordered population with respect to myosin filament structure. Within the disordered population, some are weakly attached to actin and others are detached. The fraction of cross-bridges in the helically ordered assembly is primarily a function of temperature, while the distribution between the weakly attached and the detached within the disordered population is mainly affected by ionic strength. Some other notable features in the diffraction patterns include a approximately 1% decrease in the pitch of the myosin helix as the temperature is raised from 4 degrees C to 20 degrees C.

Actins↗

Psoas muscle abscess due to Yersinia enterocolitica.

A psoas muscle abscess due to Yersinia enterocolitica developed in a 71-year-old man with mild type II diabetes mellitus. There was no evidence of gastrointestinal infection or septicemia, and treatment with computed tomography-directed percutaneous drainage and cefoxitin resulted in cure. This represents the first known reported case of psoas abscess due to Y. enterocolitica.

Abscess↗

Solitary psoas muscle metastasis after radical nephrectomy for renal cell carcinoma.

Skeletal muscle is a very rare location for the metastasis of renal cell carcinoma (RCC) and only one case of solitary metastasis to the psoas muscle has been reported. We present a 63-year-old male patient with late recurrence (14 years) after left side radical nephrectomy for RCC. He first visited Chikushi Hospital, Fukuoka University, Japan in January 2000 for a postoperative follow-up because he had shifted residence to the area. Follow-up was by abdominal computed tomography (CT) and chest X-ray. In December 2001, a CT scan showed a 1.5 cm enhanced mass in the right psoas muscle without any other metastasis. The mass was resected that month and histological study showed RCC metastasis.

Carcinoma, Renal Cell↗

Regression of polyneural innervation in the human psoas muscle.

During the early stages of mammalian ontogeny muscle fibres are innervated by more than one axon. This polyneural innervation is replaced by mononeural innervation in the course of development. The regression of polyneural innervation in the psoas muscle in the human is the topic of the present study. Innervation patterns were studied in fetuses from 15 1/2 weeks of post menstrual age (PMA) and in babies until 80 weeks PMA (40 weeks after term age) and compared to data from two adults. Motor endplates were stained by a combined acetylcholinesterase stain. Innervation patterns and motor endplate morphology were studied and the sizes of endplates were measured. As a main result of our study polyneural innervation of the psoas muscle remains at a level of about 2 endings per endplate (range 1-5 terminals) until 18-25 weeks PMA and decreases thereafter. From 52 weeks PMA (12 weeks post term) onwards, muscle fibres are predominantly mononeurally innervated. During development the morphology of the terminal patterns of the nerve endings becomes more complex and the size of endplates increases, implying that the adult pattern of muscle innervation is reached at the age at which a major functional transformation in the neurobehavioural repertoire occurs (i.e. the end of the second and the beginning of the third month.

Acetylcholinesterase↗

Ascending colon compression by psoas muscle hypertrophy.

Extrinsic compression of the ascending colon was observed on the barium enema of a professional athlete. Ultrasound examination demonstrated psoas muscle enlargement as the cause of this abnormal radiographic finding. The effect of psoas muscle hypertrophy should be considered when extrinsic compression of the colon is observed on the barium enema of muscular individuals. Ultrasound is useful to differentiate anatomic variant from pathological conditions which may deviate the ureters and/or the ascending colon.

Adult↗

Myofibrillar ATPase activity and mechanical performance of skinned fibres from rabbit psoas muscle.

1. The relationship between energy turnover and mechanical performance was investigated in chemically skinned single fibres from rabbit psoas muscle at 15 degrees C, pH = 7.1, with MgATP, 5 mM; free Mg2+, 1 mM; ionic strength, 200 mM and sarcomere length, 2.4 microns by measuring force production and myofibrillar ATP turnover during isometric contractions as well as during repetitive changes in length. ATP hydrolysis was stoichiometrically coupled to the breakdown of NADH, which was measured photometrically via the absorption of near UV light at 340 nm. 2. Force and ATPase activity were measured during square-wave length changes of different amplitudes (1-10% of the fibre length, Lo) and different frequencies (2.5-167 Hz). The average force during the length changes was less than the isometric value and decreased with increasing amplitude and frequency. At full activation (pCa 4.5), the isometric ATP turnover rate (+/- S.E.M.) was 2.30 +/- 0.05 s-1 per myosin head. ATP turnover increased monotonically with increasing amplitude as well as with increasing frequency until saturation was reached. The greatest increase observed was 2.4 times the isometric value. 3. Force and ATPase activity were also determined for ramp shortenings followed by fast restretches. The average force decreased with increasing shortening velocity in a hyperbolic fashion. The ATP turnover increased with ramp velocity up to 0.5 L0 s-1 and stayed almost constant (at 2.2 times the isometric value) for larger velocities. 4. Isometric force and ATPase activity both decreased as the calcium concentration was decreased. They did not vary in proportion at low Ca2+ concentrations, but this could largely be accounted for by the presence of a residual, Ca(2+)-dependent, membrane-bound ATPase. At high calcium concentrations ATPase activity during square-wave length changes was higher than the isometric value, but at low calcium concentrations (pCa > 6.1), the ATPase activity during the length changes decreased below the isometric value and reached a minimum of 40% of the isometric level. 5. ATPase activity and average force obtained during changes in length show a high, movement protocol-independent correlation. During the length changes the rate of ATP turnover divided by the average force level (tension cost) was larger than the isometric tension cost. The largest value found, for 10% length changes at 23 Hz, was 17 times the tension cost under isometric conditions.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine Triphosphatases↗

Enlarged psoas muscle and iliopsoas bursitis associated with a rapidly destructive hip in a patient with rheumatoid arthritis.

A 39-year-old man with rheumatoid arthritis developed femoral neuropathy secondary to iliopsoas bursitis. The adjacent hip joint was severely damaged. Magnetic resonance imaging showed enlargement and inflammation of the psoas muscle at the same side of iliopsoas bursitis. Iliopsoas bursitis and abnormal findings of the psoas muscle disappeared while the symptoms improved.

Adult↗

Dynamic retraction of the psoas muscle to expose the lumbar spine using the retroperitoneal approach. Technical note.

The retroperitoneal surgical approach has gained acceptance as a way to access the ventral aspect of the lumbar spine. Visualization is often limited, however, by the psoas muscle, which lies along the posterolateral aspect of the spine. Improved visualization is often attempted by retracting the muscle from the wound, which generally pulls the muscle laterally from the spine but not posteriorly, which is desirable for a better exposure of the spine, particularly the neural elements. In this paper, the authors describe a simple, atraumatic technique for retraction of the psoas muscle that allows excellent visualization of the spine.

Humans↗

Temperature-dependent transitions of the myosin-product intermediate at 10 degrees during Mn(II)-ATP hydrolysis by myosin from rabbit psoas muscle.

The initial burst of Pi liberation during the hydrolysis of Mn(II)-ATP by heavy meromyosin from rabbit psoas muscle was investigated. Below 10 degrees, the initial burst of Pi liberation was inhibited by the pre-addition of ADP without any change in the steady-state activity, but it was not inhibited above 10 degrees. The burst size was about one mole per mole of heavy meromyosin. The initial burst of Pi liberation in Mg-ATP hydrolysis at 8 degrees, however, was not inhibited by the pre-addition of ADP. These results, obtained with psoas muscle heavy meromyosin, were almost the same as those obtained with heavy meromyosin from rabbit leg and back muscles (Hozumi and Tawada (1975) Biochim. Biophys. Acta 376, 1-12) and, therefore, indicate that in Mn-ATP above 10 degrees there is at the burst site a predominant myosin -product complex generated by ATP hydrolysis. Similarly, below 10 degrees there is a myosin-product complex identical with the one generated by adding ADP (and Pi) to myosin.

Adenosine Triphosphatases↗

Thin filament activation probed by fluorescence of N-((2-(iodoacetoxy)ethyl)-N-methyl)amino-7-nitrobenz-2-oxa-1,3-diazole-labeled troponin I incorporated into skinned fibers of rabbit psoas muscle.

A method is described for the exchange of native troponin of single rabbit psoas muscle fibers for externally applied troponin complexes without detectable impairment of functional properties of the skinned fibers. This approach is used to exchange native troponin for rabbit skeletal troponin with a fluorescent label (N-((2-(iodoacetoxy)ethyl)-N-methyl)amino-7-nitrobenz-2-oxa-1, 3-diazole, IANBD) on Cys(133) of the troponin I subunit. IANBD-labeled troponin I has previously been used in solution studies as an indicator for the state of activation of reconstituted actin filaments (. Proc. Natl. Acad. Sci. USA. 77:7209-7213). In the skinned fibers, the fluorescence of this probe is unaffected when cross-bridges in their weak binding states attach to actin filaments but decreases either upon the addition of Ca(2+) or when cross-bridges in their strong binding states attach to actin. Maximum reduction is observed when Ca(2+) is raised to saturating concentrations. Additional attachment of cross-bridges in strong binding states gives no further reduction of fluorescence. Attachment of cross-bridges in strong binding states alone (low Ca(2+) concentration) gives only about half of the maximum reduction seen with the addition of calcium. This illustrates that fluorescence of IANBD-labeled troponin I can be used to evaluate thin filament activation, as previously introduced for solution studies. In addition, at nonsaturating Ca(2+) concentrations IANBD fluorescence can be used for straightforward classification of states of the myosin head as weak binding (nonactivating) and strong binding (activating), irrespective of ionic strength or other experimental conditions. Furthermore, the approach presented here not only can be used as a means of exchanging native skeletal troponin and its subunits for a variety of fluorescently labeled or mutant troponin subunits, but also allows the exchange of native skeletal troponin for cardiac troponin.

Actin Cytoskeleton↗

Effects of sarcomere length and temperature on the rate of ATP utilisation by rabbit psoas muscle fibres.

1. The steady state rate of ATP utilisation by single permeabilised fibres from rabbit psoas muscle immersed in silicone oil was measured using a linked enzyme assay that coupled ADP production to the oxidation of NADH.2. At sarcomere length 2.5 microm, at 10 degrees C, the rate of ATP utilisation in relaxing conditions was 6 +/- 1 microM s-1 (mean +/- S.E.M., n = 8 fibres); during isometric contraction it was 310 +/- 10 microM s-1 (mean +/- S.E.M., n = 11). Assuming a myosin active site concentration of 150 microM, these values correspond to rates of ATP utilisation per active site of about 0.04 and 2.1 s-1, respectively. 3. The rate of ATP utilisation in relaxing conditions was independent of sarcomere length in the range 2.5-4.0 microm. The rate of ATP utilisation during isometric contraction had a dependence on resting sarcomere length similar to that of isometric force in the range 2.5-4.0 microm, but was less strongly dependent on sarcomere length than was isometric force in the range 1.5-2.5 microm. 4. The rate of ATP utilisation in relaxing conditions had a Q10 of 2.5 in the temperature range 7-25 degrees C, but this increased to 9.7 in the range 25-35 degrees C, suggesting that some active force may have been generated in relaxing solution at temperatures above 25 degrees C. 5. The rate of ATP utilisation during isometric contraction had a Q10 of 3.6 throughout the temperature range 7-25 degrees C; this was similar to the Q10 for isometric force at low temperature (3.5 at 7-10 degrees C) but much larger than that for isometric force at higher temperature (1.3 at 20-25 degrees C). 6. Application of the NADH-linked assay to single muscle fibres in oil improves the effective sensitivity and time resolution of the method, and allows continuous measurements of the rate of ADP production during active contraction.

Adenosine Triphosphate↗

Chronic expanding hematoma in the psoas muscle.

We report an unusual case of chronic expanding hematoma in the psoas muscle. A 53-year-old man was admitted for evaluation of a mass shadow in the left lower lung field on chest X-rays. He had also been suffering from dull left back pain. A computed tomography scan showed a cystic lesion with a rim enhancement in the left retroperitoneal space. Mixed signal intensity in a mosaic pattern was seen on a T2-weighted magnetic resonance image. We could not rule out a suspicion of a neoplastic intratumoral hemorrhage. Due to increased pain and the definite diagnosis, surgery was performed. Histopathological examination confirmed the diagnosis of chronic expanding hematoma. The expansion process is thought to be due to the irritant effects of blood and its breakdown products, which cause repeated exudation and bleeding from capillaries in the granulation tissues.

Chronic Disease↗

[Hematoma of the iliac psoas muscle. 29 cases].

We present 29 cases of haematoma of the iliac psoas muscle, following anticoagulant treatment and review 158 cases so far published. In 60 p. 100 of cases, the anticoagulant was some form of intravenous or subcutaneous heparin; prescribed in 40 p. 100 of cases for venous thrombosis followed rapidly by pulmonary embolism, in half the cases between the 3rd and the 14th day. Hypocoagulation was excessive in 64 p. 100 of the cases. Clinically the onset is marked in all cases by a violent pain in the territory of femoral nerve, anaemia (40 p. 100) psoïtis (32 p. 100) and iliac mass (51 p. 100), ecchymosis (13 p. 100) and particularly 23 among 29 cases an early or late femoral paralysis. The clinical diagnosis has been confirmed by echography 21 cases an or CT scan (7 cases). Our approach has been definitely surgical. The surgical procedure carried out in 20 p. 100 of the cases published, and in 23 of our ones, relieves the pain, provides for an early efficient physiotherapy, and a regression of the femoral paralysis, much more rapidly and completely than in the absence of surgery. The anatomical lesions, and the condition of the femoral nerve are described in the operative records, account for that evolution and explain our position. Traumatic and hemophilic have evocated.

Adult↗

Resection of a tumor of the psoas muscle.

A 16-year-old boy presented with paresthesias and weakness of the right thigh. A computerized axial tomography scan identified a mass within the right psoas muscle, and a needle biopsy showed a primitive neuroectodermal tumor, which did not respond to two courses of chemotherapy (Adriamycin, vincristine, and cytoxan). An anatomic resection of the psoas muscle and femoral nerve was performed and radiotherapy administered. The boy remains ambulatory and free of disease 2.5 years after resection.

Adolescent↗