Method of quantitative anatomical study of the dorsal neck muscles

Summary Biomechanical models of the cervical spine require knowledge of the position, size and orientation of the individual muscles that act on the cervical spine. We have developed a technique to stereometrically measure anatomical specimens. The apparatus is composed of three graduated metallic rods, which slide along a fixed support. This method is accurate to map the anatomy of individual muscles and provides quantitative data on their lines of action. Results are obtained from one specimen. The computer processing of the collected data allows formulation of a three-dimensional model of the neck muscles in man.

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Méthode d'étude anatomique quantitative des muscles de la nuqueEtude préliminaire

Résumé Pour élaborer un modèle biomécanique de la colonne cervicale, il faut connaître la position, la taille et l'orientation des différents muscles du cou. Nous avons mis au point une méthode de mesure stéréométrique sur des sujets anatomiques. L'appareil est composé de 3 axes métalliques gradués qui coulissent sur un support fixe. Cette technique permet une étude anatomique précise de chacun des muscles de la nuque, fournissant des données quantitatives sur les différents faisceaux ou lignes d'action. Les résultats sont obtenus sur un sujet. Leur traitement informatique permettra l'élaboration d'un modèle mathématique tridimensionnel des muscles du cou chez l'homme.

     

Effect of denervation of the working capacity of muscles

In acute experiments on cats, the working capacity of the leg muscles during stimulation of the sciatic nerve was increased after division of the sciatic and femoral nerves. This effect was not due to changes in the circulation, for it persisted if the blood flow was stabilized. Increased working capacity was also manifested after partial deafferentation of the limb by division of the dorsal roots of the spinal cord or extirpation of the tibial bone marrow.Laboratory of Experimental Physiology, Latvian Research Institute of Experimental and Clinical Medicine, Riga. (Presented by Academician V. N. Chernigovskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 79, No. 2, pp. 6–8, February, 1975.     

Detection of skeletal muscle fatigue using an accelerometer in dynamic cardiomyoplasty

 An animal experiment was done using six mongrel dogs that weighed 28 ± 3 kg to show that an accelerometer could detect skeletal muscle fatigue in dynamic cardiomyoplasty. Through left-side thoracotomy, the heart was exposed and an electrode to sense the heartbeat was positioned on the left ventricle. A left latissimus dorsi muscle flap (LDMF) was inserted into the left chest cavity and rolled around the heart. An accelerometer was put on the rolled LDMF to sense the ventricular acceleration by contraction of the LDMF and the heart. The LDMF was stimulated under these settings: pulse width, 210 μs; stimulation output, 6 V; burst frequency, 30 Hz; burst duration, 200 ms; synchronous ratio, 1 : 4; and synchronous delay, 66 ms. Output voltage from the accelerometer was recorded 1, 3, 5, 10, and 15 min after the beginning of stimulation. Percentages of the amplitude in all dogs after 3, 5, 10, and 15 min were 81 ± 10%, 63 ± 12%, 48 ± 11%, and 45 ± 14% of the values after 1 min, respectively. Significant differences were found between the values after 1 min and those after 3 min, between the values after 3 min and those after 5 min, and between the values after 5 min and those after 10 min. This study suggests that muscle fatigue is detectable with an accelerometer in actual dynamic cardiomyoplasty. Received: May 11, 2001 / Accepted: September 10, 2002 Acknowledgments This work was financially supported in a part by a Grant in Aid for Scientific Research (05671113) from the Ministry of Education, Science, and Culture of Japan. Correspondence to:H. Kuroda     

Extracellular Ca2+-dependent and independent calcium transient in fetal myotubes

Spatio-temporal changes in the intracellular calcium concentration [Ca²⁺]_i of dissociated mice myotubes from 14-day and 18-day-old fetuses were studied using digital imaging analysis of the Ca²⁺ indicator fura-2. Myotubes from 18-day-old fetuses displayed a transient [Ca²⁺]_i increase upon electrical stimulation either in nominally calcium-free external solution or in Krebs solution containing 100 M lanthanum. Thus, at this developmental stage, membrane depolarization appears to increase [Ca²⁺]_i by stimulating Ca²⁺ release from the sarcoplasmic reticulum independently of extracellular Ca²⁺ influx. Similarly, myotubes from 14-day-old fetuses also showed a calcium transient upon electrical stimulation in Krebs solution. However, in 46% of these myotubes the calcium transient was abolished when Ca²⁺ entry through calcium channels was suppressed.     

Excitation of units in the lateral geniculate and contiguous nuclei of the cat by stretch of extrinsic ocular muscles

Summary In cats, anaesthetized with chloralose and paralysed, the responses of units in the right lateral thalamus were recorded while the extrinsic ocular muscles (EOM) of the right eye were stretched in the dark. Phasic responses were found in all layers of the dorsal lateral geniculate nucleus (LGNd) and in the perigeniculate nucleus (PGN). A given unit usually responded to stretch of more than one EOM and thus to more than one direction of rotation of the eye in the orbit. LGNd. Of a sample of 76 units in LGNd, 55 (72%) gave visual but no muscle responses and 21 (28%) responded to EOM stretch. In all, 40 units with EOM responses were examined and 25 of the 27 tested (93%) also had visual responses. Of the 40 units, 32 could be allocated to layers, thus: layer A, 8 (25%); layer A1, 20 (63%); layer B, 3 (9%); central interlaminar nucleus, 1 (3%). It is interesting that most of the EOM responses were found in layer A1 which receives the excitatory visual input from the eye whose EOM were stretched. Muscle responsive units occurred with ON- and OFF-centre visual responses of sustained and transient types. PGN. In PGN, 21 units gave EOM responses and most of them were also excited by visual input.The conclusion is that the LGNd and PGN recieve an extraretinal proprioceptive signal which should be present during at least large saccadic eye movements. The anatomical pathways which may be involved and the significance of the signal are discussed briefly.     

Loads applied tangential to a fingertip during an object restraint task can trigger short-latency as well as long-latency EMG responses in hand muscles

Electrical stimulation of the digital nerves can cause short- and long-latency increases in electromyographic activity (EMG) of the hand muscles, but mechanical stimulation of primarily tactile afferents in the digits generally evokes only a long-latency increase in EMG. To examine whether such stimuli can elicit short-latency reflex responses, we recorded EMG over the first dorsal interosseous muscle when subjects (n=13) used the tip of the right index finger to restrain a horizontally oriented plate from moving when very brisk tangential forces were applied in the distal direction. The plate was subjected to ramp-and-hold pulling loads at two intensities (a 1-N load applied at 32 N/s or a 2-N load applied at 64 N/s) at times unpredictable to the subjects (mean interval 2 s; trial duration 500 ms). The contact surface of the manipulandum was covered with rayon—a slippery material. For each load, EMG was averaged for 128 consecutive trials with reference to the ramp onset. In all subjects, an automatic increase in grip force was triggered by the loads applied at 32 N/s; the mean onset latency of the EMG response was 59.8±0.9 (mean ± SE) ms. In seven subjects (54%) this long-latency response was preceded by a weak short-latency excitation at 34.6±2.9 ms. With the loads applied at 64 N/s, the long-latency response occurred slightly earlier (58.9±1.7 ms) and, with one exception, all subjects generated a short-latency EMG response (34.9±1.3 ms). Despite the higher background grip force that subjects adopted during the stronger loads (4.9±0.3 N vs 2.5±0.2 N), the incidence of slips was higher—the manipulandum escaped from the grasp in 37±5% of trials with the 64 N/s ramps, but in only 18±4% with the 32-N/s ramps. The deformation of the fingertip caused by the tangential load, rather than incipient or overt slips, triggered the short-latency responses because such responses occurred even when the finger pad was fixed to the manipulandum with double-sided adhesive tape so that no slips occurred.     

Dynamometer for rat plantar flexor musclesin vivo

A dynamometer is designed and fabricated to measure the force output during static and dynamic muscle actions of the plantar flexor muscles of anaesthetised rats in vivo. The design is based on a computer-controlled DC servomotor capable of angular velocities in excess of 17.5 rad s⁻¹. The system controls the range of motion, angular velocity and electrical stimulation of the muscles, while monitoring the force output at the plantar surface of the foot. The force output is measured by a piezo-electric load cell that is rated at 5 kg capacity. Angular velocity and position are measured by a DC tachometer and potentiometer, respectively. All measurement devices are linear (r²=0.9998). The design minimises inertial loading during high-speed angular motions, with a variation in force output of less than 0.2%. The dynamometer proves to be an accurate and reliable system for quantifying static and dynamic forces of rat plantar flexor muscles in vivo.     

缺血后处理改善微循环、减轻骨骼肌缺血再灌注损伤的实验研究

目的:观察缺血后处理(I-postC)对大鼠后肢骨骼肌微循环和缺血再灌注(I/R)损伤的影响。方法:健康雄性Wistar大鼠24只,随机分为3个实验组,即I/R组、I-postC组和预处理(IPC)组(n均=8),左后肢作为自身对照。无创动脉夹夹闭右侧股动脉4h,松夹再灌注2h建立大鼠后肢I/R模型。于再灌注结束时分别检测大鼠胫前肌血氧饱和度(StO2)、微循环、血流动力学变化以及骨骼肌湿、干重比值(W/D)和骨骼肌组织丙二醛(MDA)含量。结果:(1)再灌注I-postC减轻I/R对心功能的抑制,I-postC组+dp/dtmax和-dp/dtmax较I/R组分别增高18.5%和21.3%(P<0.05),I-postC组W/D较I/R组降低4.9%(P<0.05);I-postC组MDA较I/R组降低40.9%(P<0.05)。(2)再灌注I-postC组实验侧细静脉血流速度较I/R组增加8.3%(P<0.05),细动、静脉收缩减轻(细动、静脉内径较I/R组分别增加14.8%和29.1%,P<0.05),与IPC的保护效果接近(P>0.05)。结论:I-postC显著减轻骨骼肌I/R损伤,其保护机制与改善微循环有关。     

Lectin binding and desmin expression during necrosis, regeneration, and neurogenic atrophy of human skeletal muscle

Changes in the cytoplasm of skeletal muscle fibres during necrosis, regeneration, and neurogenic atrophy have been studied in a wide range of human neuromuscular diseases with a panel of eleven biotinylated lectins and by immunohistochemical staining for the cytoskeletal protein desmin. Increased binding of several lectins was observed in both necrotic and regenerating fibres, with Concanavalin A the most consistently positive lectin. Staining for desmin was strong in the cytoplasm of regenerating and partially damaged fibres and was lost in necrotic fibres, although there were differences in the staining reactions of the two antidesmin antibodies used. In fibres which had undergone neurogenic atrophy, cytoplasmic lectin binding was seen only with Griffonia simplicifolia 1 lectin, and desmin was expressed more strongly than in normal fibres. Lectin binding and immunohistochemical staining from desmin can supplement the information obtained from muscle biopsies by conventional histochemical methods and lead to a better understanding of the mechanisms of muscle damage.     

Lipid metabolism during exercise I: Physiological and biochemical characterization of normal healthy male subjects in relation to their physical fitness

Summary On the basis of maximal oxygen uptake ( O₂ max) 18 normal, healthy men were divided into two groups of equal size: moderately trained subjects (MTR) each having O₂ max below 65.0 ml·min^–1·kg^–1 body weight (54.0±8.3) and well trained subjects (WTR), whose O₂ max exceeded 65.0 ml·min^–1·kg^–1 body weight (69.2±4.1). The WTR group had slightly (non significant, n.s.) higher percentage of slow twitch, oxidative (SO) fibers in M. vastus lateralis and higher (n.s.) activities of cytochrome c oxidase (CytOx), succinate dehydrogenase (SDH), 3-hydroxyacyl-CoA-dehydrogenase (HADH), and citrate synthase (CS), while lactate dehydrogenase (LDH) activity was lower (n.s.). In the MTR group only, the SO-%, and the activities of CytOx, SDH and HADH correlated positively with O₂ max, and LDH negatively with O₂ max. These correlations were not significant in the WTR group possibly because of the adaptations produced by training in this group. Multiple regression analysis was used to elucidate the best combination of variables to explain the variance in O₂ max. The best model consisted of the sum of relative activities of oxidative muscle enzymes (CytOx, SDH, HADH, CS), muscle LDH activity, body fat content (% F) and lean body mass. This model explained 69% of the variance in O₂ max; and of the individual variables % F was of utmost importance.