P-31 MR spectroscopy of skeletal and cardiac muscle metabolism in patients with systemic sclerosis: A multiple case study

Three-dimensionally localized proton-decoupled phosphorus-31 magnetic resonance (MR) spectroscopy of skeletal and cardiac muscle was performed in six patients with systemic sclerosis. Cardiac (n = 9) and skeletal (n = 6) spectra were also obtained in healthy volunteers. Metabolite ratios and intracellular pH were determined from the spectra of skeletal and cardiac muscle. The phosphocreatine-to-adenosine triphosphate ratio was normal for both skeletal and cardiac muscle in patients with systemic sclerosis. The pH values of skeletal muscle were similar in patients and control subjects (7.13 ± 0.02 vs 7.12 ± 0.01, respectively). In skeletal muscle, the inorganic phosphate-to-phosphocreatine ratio in patients was increased relative to that of control subjects (0.106 ± 0.014 vs 0.086 ± 0.006, respectively; P =.02). P-31 MR spectroscopy showed no abnormalities in the myocardium of patients with systemic sclerosis. Assessment of the inorganic phosphate-to-phosphocreatine ratio in peripheral skeletal muscle may be helpful for assessing disease activity.     

Measurement of skeletal muscle motion in vivo with phase-contrast MR imaging

The ability to measure skeletal muscle motion with phase-contrast magnetic resonance (MR) imaging was tested with a motion phantom that simulated muscle activity. Quantitative analytic data on unidimensional, bidirectional skeletal muscle motion measured in vivo was obtained in four healthy volunteers. MR images of the subjectss' forearms were obtained during flexion and extension of the fingers and of the anterior and posterior muscle compartments of the lower leg with various resistances to ankle dorsiflexion and plantar flexion. It was necessary to correct the data for the effects of eddy currents. In vitro evaluation of the technique was done by studying through-plane sinusoidal motion of solid objects. The largest error was underestimation of the peak excursion of 11.5 mm by 0.09 mm (the root mean square error for the cycle was 0.04 mm) In vivo experiments demonstrated the contraction of muscles in relation to each other. Data acquisition and analysis techniques must be refined, but measuring skeletal muscle motion with phase-contrast MR imaging should enhance the understanding of bioengineering fundamentals and muscular changes in disease and adaptation.     

人参二醇组皂甙及游泳训练对大鼠股四头肌α-肌动蛋白mRNA表达的影响

目的:观察大鼠7周大负荷游泳训练及人参二醇组皂甙(PDS)对大鼠股四头肌α-肌动蛋白mRNA表达的影响。方法:采用Northernblot分析7周大负荷游泳训练后恢复期大鼠股四头肌α-肌动蛋白mRNA表达水平及PDS对其影响。结果:α-肌动蛋白mRNA杂交信号的扫描积分光密度值(A),运动·盐水组较安静组略强;运动·PDS,扫描积分光密度值(A)显著强于运动·盐水组和安静组,运动·甲睾组与运动·盐水组表达无明显差异。结论:PDS可提高长期耐力运动大鼠股四头肌α-肌动蛋白mRNA表达,从而提高耐力运动能力;长期应用外源性雄激素对耐力训练大鼠股四头肌α-肌动蛋白无明显提高,这可能与外源睾酮对内源性睾酮分泌的抑制有关。     

体外培养诱导大鼠骨髓间质干细胞分化为肌样细胞的实验研究

目的:体外培养并诱导大鼠骨髓间质干细胞(MSCs)分化为肌样细胞。方法:采用常规技术对SD鼠MSCs进行体外培养传代、鉴定、诱导分化和免疫组化、透射电镜检测分析。结果:流式细胞仪检测, 细胞表达CD29和CD44, 不表达CD11b和CD45;经一定浓度5-氮杂胞苷和两性霉素B诱导分化后细胞desmin和myoglobin染色阳性;电镜观察肌样细胞胞浆靠胞膜缘可见无细胞器的条状肌丝区带。结论:传代贴壁生长的梭形细胞为MSCs。MSCs可能具有表达肌细胞的特异性启动或分化调控基因;5-氮胞苷等化合物可使DNA的胞嘧啶去甲基化, 从而诱导MSCs向肌源性细胞分化。临床有运用MSCs治疗肌萎缩性疾病的前景。     

Accuracy of internal dynamics models in limb movements depends on stability

This study investigated the ability to use an internal model of the environmental dynamics when the dynamics were predictable but unstable. Subjects performed goal-directed movements using a robot manipulandum while counteracting a force field, which created instability by assisting the movement in proportion to hand velocity. Subjects performance was better on the last trial than on the first trial in the force field for all four movement directions tested: out, in, right and left. Subjects adapted to the force field primarily by increasing muscle co-contraction, compared to null field movements, during all phases of movement. This co-contraction generally declined for both the deceleration and stabilization phases during the course of the first 25 movements in each direction, but tended not to decrease significantly thereafter. Catch trials at the end of the learning period suggested that increased viscoelastic impedance due to muscle co-contraction was used to counteract the force field. Only in the case of outward movements were aftereffects observed that were consistent with formation of an accurate internal model of the force field dynamics. Stabilization of the hand for outward movements required less muscle co-contraction than for movements in other directions due to stability conferred by the geometry of the arm. The results suggest that the accuracy of an internal model depends critically on the stability of the coupled dynamics of the limb and the environment.     

M. articularis genus Observations on arrangement and consideration of function

Summary On the basis of 44 adult Japanese cadavers, the mode of origin, insertion and innervation of the articularis genus muscle (m. articularis genus: AG) is described. All the muscle bundles that are inserted into the posterior aspect of the synovial membrane of the joint capsule as well as the suprapatellar bursa are defined as AG. The inserting fibers spread medially and laterally over the subsynovial connective tissue which is the outer layer of synovial membrane facing the femur. The fatty tissue between each muscle bundle gradually increases with depth. A few deeper muscle bundles of AG seem to be separated by a layer of fat from those of the superficial layer. The deepest muscle bundles arise from the anterior surface of the femur at a slighlty lower level than the proximal apex of the suprapatellar bursa. It is inserted into the synovial membrane at the level of the junction of the suprapatellar bursa and proper joint cavity when the knee is extended. It is difficult to distinguish AG from m. vastus intermedius (Vi) only on the basis of the manner of origin and the surrounding fatty tissue. The innervation is in common with that of Vi, namely, a few nerves which run down obliquely to the lower medial part of Vi.Dedicated to Professor Emeritus Tomoo Nakayama in commemoration of his 77th birthday     

Soft tissue pseudotumor following intramuscular injection of “DPT”: a pitfall in magnetic resonance imaging

We report the time-dependent magnetic resonance imaging (MRI) changes that resulted from an intramuscular injection of a commonly-used pediatric sedation regimen (DPT). These changes at the site of injection consist of a focal abnormality characterized by a slight increase in signal intensity on T1 weighted images and markedly increased signal intensity on T2 weighted images. Alterations in signal are detectable almost immediately after the injection and progress over the first 31 hours. This abnormality, which could be mistaken for real disease, persists up to 36 days following injection.     

Adductor pollicis. The missing interosseous

Summary This paper highlights the many similarities between the adductor pollicis and the palmar interossei. In particular it compares their anatomy, innervation and function. It suggests that adductor pollicis should be considered as the first palmar interosseous and that this view simplifies the teaching of hand anatomy and the tests of ulnar nerve function. Further support for the view that adductor pollicis is the thenar counterpart of the second, third and fourth palmar interossei is gained from studies of the literature on hand evolution, in particular published details of fossil records and dissection of primate hands.

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L'adducteur du pouce : l'interrosseux perdu

Résumé Cet article souligne les nombreuses similitudes qui existent entre le m. adducteur du pouce et le m. premier inter-osseux palmaire. Il compare en particulier l'anatomie l'innervation et la fonction de ces muscles. Le m. adducteur du pouce semble bien devoir être considéré comme le m. premier inter-osseux palmaire et ce point de vue simplifie l'enseignement de l'anatomie de la main ainsi que l'évaluation de la fonction du nerf ulnaire. Des arguments supplémentaires en faveur de l'hypothèse d'un m. adducteur du pouce qui serait la contre-partie thénarienne des second, troisème et quatrième mm. inter-osseux palmaires proviennent de l'étude de la littérature concernant la phylogénèse de la main et en particulier des résultats d'études portant sur les fossiles et les dissections de mains de primates.

     

Functionally complex muscles of the cat hindlimb

The biceps femoris (BF) muscle is divided into three neuromuscular compartments defined by the innervation patterns of the main nerve branches (English and Weeks 1987). The goals of this study were i) to determine how different regions of the biceps femoris muscle are activated in the intact cat during a broad range of limb movements evoked by perturbations of stance posture, and ii) to determine the relationship between the anatomical compartments of biceps femoris and the functional units as defined in this task. Cats were trained to stand on a moveable platform with each paw on a triaxial force plate. The animal's stance was perturbed by linear translation of the platform in each of sixteen different directions in the horizontal plane. EMG activity was recorded from eight sites across the width of the left biceps femoris muscle. During quiet stance only the anterior compartment was tonically active, presumably contributing to hip extensor torque in the maintenance of stance. During platform translation, evoked EMG activity was recorded from each electrode pair for a wide range of directions of perturbation; as direction changed progressively, the amplitude of evoked activity from any electrode pair increased to a maximum and then decreased. When the EMG amplitude was plotted in polar coordinates as a function of translation direction, the region of response formed a petal shaped area in the horizontal plane, termed the EMG tuning curve. The compartments of the BF muscle were not activated homogeneously. The tuning curve of the anterior BF compartment was similar to that of other hip extensors, and coincided with the region of postero-lateral force production by the hindlimb against the support. The tuning curve of the middle BF compartment was shifted in a counterclockwise direction from that of the anterior compartment, but overlapped extensively with it; the middle BF tuning curve was similar to that of anterior gracilis. The tuning curve of the posterior biceps compartment was rotated further counterclockwise and overlapped very little with that of the middle BF compartment. The posterior BF was activated in a pattern similar to that of other knee flexors. The functional units of BF activation were not identical with the neuromuscular compartments defined by the main nerve branches. As direction of the perturbation changed, the region of BF that was activated moved progressively across the muscle. This progression of the active region was continuous across BFa and BFm, whereas there was a jump, or discontinuity at the border between BFm and BFp.(ABSTRACT TRUNCATED AT 400 WORDS)