屈肌起点滑移术治疗前臂缺血性肌挛缩

目的介绍屈肌起点滑移术治疗前臂缺血性肌挛缩的手术时机和疗效。方法作者为７例前臂缺血性肌挛缩作该手术。根据其病理演变过程和术中发现，将其临床分型归纳为６型。结果术中发现：前臂深层屈肌变性、挛缩较浅层屈肌严重。术后疗效为优者（Ｓ３Ｍ４）４例，良（Ｓ３Ｍ３）２例，可（Ｓ２Ｍ２）１例。手术时机以选择纤维化、挛缩期效果较好。在吸收再生期如神经损害在继续加重时也应手术。结论足够的肌起点剥离与适当的滑移距离，切除一切变性、坏死、挛缩的肌肉与筋膜，切开卡压神经的纤维索带、腕管与腕尺管，彻底松解神经等是手术成功的关键     

Pain from excitation of identified muscle nociceptors in humans

The technique of intraneural microstimulation (INMS) combined with microneurography was used to excite and to record impulse activity in identified afferent peroneal nerve fibers from skeletal muscle of human volunteers. Microelectrode position was minutely adjusted within the impaled nerve fascicle until a reproducible sensation of deep pain projected to the limb was obtained during INMS. During INMS trains of 5–10 s in duration and at threshold for sensation, volunteers perceived a well defined area of deep pain projected to muscle. Psychophysical judgements of the magnitude of pain increased with increasing rates of INMS between 5 and 25 Hz. Also, the area of the painful projected field (PF) evoked during trains of INMS of various duration but constant intensity and rate typically expanded with duration of INMS. The intraneural microelectrode was alternatively used to record neural activity originating from primary muscle afferents. Eight slowly adapting units with moderate to high mechanical threshold were identified by applying pressure within or adjacent to the painful PF. Conduction velocities ranged from 0.9 to 6.0 m/s, and fibers were classed as Group III or Group IV. Capsaicin (0.01%) injected into the RF of two slowly conducting muscle afferents (one Group III and one Group IV) produced spontaneous discharge of each fiber and caused intense cramping pain, suggesting that the units recorded were nociceptive. Our results endorse the concept that the primary sensory apparatus that encodes the sensation of cramping muscle pain in humans is served by mechanical nociceptors with slowly conducting nerve fibers. Results also reveal that muscle pain can be precisely localized, although the human cortical function of locognosia for muscle pain becomes blunted as a function of duration of the stimulus.     

Stability constraints for the distributed control of motor behavior

We have investigated the relation between static stability of a limb, equilibrium-point control, and the ill-posed problem of coordinating a redundant ensemble of muscles. Geometrically, equilibrium-point control is equivalent to establishing a mapping between the command signals delivered to the muscles and the equilibrium configurations of a limb. A necessary condition for the existence of such mapping is that the limb be stable across the workspace. We analyzed how this condition may be translated into precise biomechanical constraints for single-and multi-joint limbs. The satisfaction of these constraints is necessary for the equilibrium-point hypothesis to be a viable control paradigm. We show how these same constraints are sufficient to insure the successful operation of a distributed algorithm based upon minimization of potential energy that computes the muscle-control signals corresponding to a desired time sequence of equilibrium points.     

The production of long-term rat muscle cell cultures on a Matrigel substrate and the removal of fibroblast contamination by collagenase

We report a simplified method modified from standard procedures for the production of long-term primary skeletal muscle monolayer cell cultures using collagenous for tissue digestion. When grown on the commercially available substrate Matrigel, such cultures are high in myotube content, remain attached to the plate surface after the initiation of spontaneous activity and do not need to be treated with mitotic inhibitors to control fibroblast proliferation. In addition cultures even more enriched for myotubes can be produced by selective removal of fibroblasts from Matrigel coated plates by collagenase. This novel procedure, along with the simplified primary culture technique, allows for highly reproducible results even for the inexperienced user.     

Measurement of muscle and tendon stiffness in man

Human first dorsal interosseous muscle was stimulated tetanically using several levels of percutaneous electrical current which produced forces in the muscle-tendon complex of between 30% and 100% of maximum. During the tetanus the muscle was subjected to a small fast stretch. The ratio of the force response to the displacement of the muscle-tendon complex gave a measure of the stiffness of the total complex. An adaptation of the method of Morgan (1977) allowed the stiffness to be separated into two components the stiffness of the muscle fibres and the stiffness of the tendon. The results showed that at full activation the stiffness of the muscle fibres and the tendon are approximately the same. The normalised stiffness values obtained in the experiments compared well with animal data.     

Intramuscular pressure in the supraspinatus muscle

Shoulder pain correlated to manual labour is an increasing problem. The etiology is multifactorial and often unclear. High local muscle load and muscle ischemia in the supraspinatus muscle is present in elevated arm positions, as shown in several electromyographic studies. The purpose of this study was to evaluate intramuscular pressure (IMP) as a way to describe local muscle load in the supraspinatus muscle. Measurements were made in 15 arm positions, and with hand loads of 0, 1, or 2 kg weight, in 12 shoulders. The IMP was recorded with microcapillary infusion technique. The method was found to be suitable in recording IMP at rest and during exercise. High intramuscular pressures, i.e., above 50 mm Hg (6.7 kPa), were seen in moderate humeral abduction. The IMP increased further in abduction up to 90 degrees, where mean IMP was 122 mm Hg (16.2 kPa). Added hand load increased intramuscular pressure in all positions except in shoulder flexion of 135 degrees. The study thus demonstrated that intramuscular pressure offers important information about the load on the supraspinatus muscle in different positions of the arm. The results indicate that fatigue and shoulder pain related to elevated arm positions may be caused by muscle ischemia induced by the high intramuscular pressure present in these positions.     

Oxygen transport and the function of myoglobin

We studied the steady-state oxygen transfer across thin layers of respiring chicken gizzard smooth muscle and compared three models for oxygen consumption with respect to their influence on the facilitation of oxygen diffusion by myoglobin. These models assumed zero-order, Michaelis-Menten or exponential kinetics. The transport equation was solved for these models with simultaneous oxygen facilitation assuming chemical equilibrium between oxygen and myoglobin. Experimental flux data were obtained in two situations: a) high oxygen pressure throughout the layer of tissue providing maximum oxygen consumption and oxygen permeability, and b) anoxic conditions in part of the layer and with submaximal oxygen consumption and desaturation of myoglobin. Measurements in the presence of functional myoglobin were compared with data obtained after abolishing the transport function of myoglobin by application of 1kPa carbon monoxide. It was found that oxygen consumption interferes with the facilitation effect. The oxygen pressure at half maximum oxygen consumption in the Michaelis-Menten model was 0.3±0.1 (S.E.) kPa. The facilitation of the oxygen transport by myoglobin was 50 to 100% of the maximum value to be expected on the basis of the prevailing myoglobin concentration.     

Phosphorylase b kinase deficiency in a boy with glycogenosis affecting both liver and muscle

A boy with marked hepatomegaly and motor weakness was investigated for glycogen storage disease. Glycogen accumulation was demonstrated in both liver and muscle and there was a deficiency of phosphorylase b kinase activity. On the basis of biochemical findings, an autosomal recessive mode of inheritance was considered likely, rather than the more common X-linked variant, with primarily liver involvement.     

Bioavailability of zinc derived from beer and the effect of low dietary zinc intake on skeletal muscle zinc concentration

The bioavailability of zinc from freeze-dried cooked beef was determined using log total tibia zinc and body weight gain as the response criteria. Control diets consisted of different levels of zinc carbonate added to an egg-white protein source. Experimental diets were made by substituting various levels of freeze-dried beef as the zinc source. All diets were isocaloric and isonitrogenous. Zinc in the control diets was utilized as effectively as zinc in the experimental diets. The relative biological value (RBV) of zinc (ZnCO₃=100) in the experimental diet was 103 for 22-day weight gain, and 102 for total tibia zinc. These results indicate that zinc from cooked beef does not have an increased bioavailability over inorganic zinc added to an egg-white protein diet. Because a, large percentage of the total zinc in an animal is found in skeletal muscle, the content of zinc in two types of skeletal muscle was determined from animals fed different levels of dietary zinc. Animals consuming diets with zinc concentrations below their requirement had depressed growth rates; however, no significant differences were found in the zinc concentrations of either the soleus or plantaris muscle. The average zinc content of the soleus muscle (slow twitch oxidative fiber type) was 69 ppm and the plantaris muscle (fast twitch oxidative fiber type) was 15 ppm. These results indicate that the concentration of zinc in skeletal muscle is not significantly reduced in animals whose growth is restricted by low dietary zinc levels.     

Involvement of fast and slow twitch muscle fibres in avian muscular dystrophy

The extent of differential fibre type involvement in chicken muscular dystrophy can be assessed quantitatively by the statistical parameters of fibre area, nuclei content and nuclei distribution in the individual fibre types. Two muscles, the posterior latissimus dorsi (PLD) and the serratus metapatagialis (SMP), were found to have similar overall fibre type composition, although the latter contains two subtypes of type I fibres, one of which has not previously been recognised in avian muscle. In both muscles, type IIB fibres are most affected by the progressive pathology. Nuclear proliferation is one of the histopathological features which can be measured, and in the PLD, the mean number of total nuclei in type IIB fibre cross-sections (N_t) is increased from 2.23 in normal chickens to 3.70 in dystrophic chickens, by 60 days. The corresponding values for N_t in type IIB muscle fibres of the SMP at 50 days are 1.74 and 5.10. Likewise, statistical analyses of the distribution of the fibre areas and their variability demonstrate that the incidence of abnormality in chicken dystrophy is greatest in type IIB fibres in both these muscles.Although type I fibres in the PLD are resistant to dystrophic change, it is noteworthy that in the SMP the type I fibres, also, are severely affected from an early stage, by these quantitative criteria. On the other hand, all fibres in a tonic muscle, the metapatagialis latissimus dorsi, are unaffected, as is true of all other tonic muscles previously studied. It is concluded that any twitch fibre type can, in principle, be affected by the actions of the gene concerned, and that this expression can be greatly modified in individual muscles by various physiological features, for example their natural pattern of use or relative disuse.