Muscle Elongation Research Articles

Observations on rheological, electrical, and optical changes during rigor development in pork and beef.

Electrical and optical changes were measured in bovine sternomandibularis and porcine sternocephalicus strips tested sinusoidally in a rigorometer up to 3 h postmortem. Rigor development was detected by decreased muscle elongation, decreased stress-strain hysteresis area, and increased elastic modulus. Elastic modulus was affected by loading rate (r = .98, P < .005) from loading rates of 3.6 to 13.3 kPa/s. Capacitance decreased and resistance increased at 120 Hz, 1 kHz, and 10 kHz as rigor developed. Sometimes changes were irregular at one frequency but steady at another. The most consistent electrical predictors of rigor development were capacitance at 120 Hz and resistance at 10 kHz. Electrical impedance changed as muscle strips were stretched in the rigorometer, so that dimensional effects could be a source of error if testing causes muscle contraction. The dominant fiber-optic reflectance changes during rigor development were increases toward 400 nm and decreases toward 700 nm, although transient increases were sometimes detected toward 700 nm. Optical changes generally were later than electrical changes. All these complex changes are an obstacle to the early prediction of pH-dependent aspects of meat quality from electrical and optical measurements.

Surgical treatment for equinus feet deformity in pre-school children with infantile cerebral paralysis

The treatment results of 184 children under school age with infantile cerebral paralysis and equinus deformity were analysed. There were 268 feet with equinus deformity. Out of 312 operations 137 (44%) Str operations, 63 (20,3%) aponeurotic elongation of gastrocnemical muscle, 56 (18,1%) Z-shape elongation of gastrocnemical muscle and 14 (4,5%) achilloplasty by Hoke-method were performed. The indications to apply the surgical management depending on the orthopedic and neurologic status as well as the methods of aponeurotic elongation of gastrocnemical muscle are presented. Excellent and good results were achieved in 86% of cases, recurrence of deformity was observed in 8% of cases. Minimum trauma, high efficiency, organ-sparing pattern of aponeurotic elongation of gastrocnemical muscle makes this procedure the method of choice in children under school age.

Instantaneous resolution of ischemic mitral regurgitation and pulmonary hypertension by angioplasty

Ischemic mitral regurgitation (MR) with pulmonary hypertension (PH) is a rare complication of coronary artery disease. It is defined as mitral valve incompetence occurring after an acute myocardial infarction with no primary leaflet or chordal pathology in 13%) and 18% of patients undergoing cardiac catheterization [l-2]. The pathogenesis is widely believed to be secondary to dyskinesis or dysfunction of the postero-medial papillary muscles in ischemia. Combinations of posterior annular dilation, papillary muscle elongation and loss of papillary muscle shortening contribute to the valve incompetence at the posterior commissural region. Fluctuating mitral regurgitation in the setting of post-infarction unstable angina is also a variant of this syndrome. Mitral regurgitation due to rupture of the papillary muscle is uncommon and is seen in only 0.1% of patients undergoing catheterization [3]. Significant improvement in morbidity from ischemic mitral regurgitation can be expected with relief of the ongoing myocardial ischemia. In this

Evaluation of mitral leaflet motion by echocardiography and jet direction by doppler color flow mapping to determine the mechanism of mitral regurgitation

Objectives. This study was designed to assess the accuracy of two-dimensional and Doppler echocardiography in determining the mechanism of mitral regurgitation, as compared with direct inspection of the valve at operation.Background. Valve repair for mitral regurgitation offers substantial advantages over valve replacement, but it is technically more demanding and requires understanding of the mechanism of dysfunction.Methods. We studied 286 patients undergoing mitral valve repair. Intraoperative two-dimensional echocardiography was used to classify mitral leaflet motion as excessive, normal or restricted. Doppler color flow mapping was used to evaluate the direction and origin of the mitral regurgitant jet. Two-dimensional and Doppler echocardiography were compared with intraoperative surgical determination of the mechanism of dysfunction, which also classified leaflet motion as excessive, normal or restricted.Results. Two-dimensional and Doppler echocardiography accurately diagnosed the mechanism of mitral regurgitation in 123 (93%) of 132 patients with posterior leaflet prolapse or flail, 30 (94%) of 32 patients with anterior leaflet prolapse or flail, 11 (44%) of 25 patients with bileaflet prolapse or flail, 6 (75%) of 8 patients with papillary muscle elongation or rapture, 31 (91%) of 34 patients with restricted leaflet motion or rheumatic thickening, 21 (72%) of 29 patients with ventricular-annular dilation and 8 (62%) of 13 patients with a leaflet perforation or cleft. Of 13 patients with two mechanisms of dysfunction by surgical inspection, two-dimensional and Doppler echocarediography correctly diagnosed one of the two mechanisms in 12 patients (92%), and both mechanisms in 5 patients (38%). Overall, echocardiographic determination of leaflet motion and Doppler determination of jet direction accurately diagnosed the mechanism of dysfunction in 242 (85%) of 286 patients.Conclusions. Echocardiography before mitral valvuloplasty provides a dynamic appraisal of the mechanism of dysfunction, enabling the surgeon to systematically understand the dysfunction and successfully apply the correct procedures to eliminate mitral regurgitation without valve replacement.

The Mechanism of Tongue Projection in Chameleons: II. Role of Shape Change in a Muscular Hydrostat

ABSTRACT In this paper we investigate the interaction between the accelerator muscle (the muscle that powers tongue projection) and the entoglossal process (the tongue’s skeletal support) that occurs during tongue projection in chamaeleonid lizards. Previous work has shown that there is a delay of about 185 ms between the onset of accelerator muscle activity and the onset of tongue projection. In conjunction with anatomical observations, in vitro preparations of the accelerator muscle mounted on isolated entoglossal and surrogate processes were stimulated tetanically, and the resulting movements were recorded on video at 200 fields s−1. Three results indicate that morphological features of the entoglossus and the accelerator muscle delay the onset of tongue projection following the onset of accelerator contrac-tion: ( 1) the entoglossus is parallel-sided along the posterior 90% of its shaft, only tapering at the very tip, (2) the sphincter-like portion of the accelerator muscle, which effects tongue projection, makes up the posterior 63% of the muscle and does not contact the tapered region of the entoglossus at rest, and (3) accelerator muscles mounted on the entoglossus undergo longitudinal extension and lateral constriction for 83 ms following the onset of electrical stimulation, before projecting off the entoglossus. It is proposed that, during elongation of the accelerator muscle, the sphincter-like region ultimately comes into contact with the tapered region of the entoglossus, causing the onset of projection. This conclusion is supported by the observation that the time between the onset of stimulation and the onset of projection was longer in preparations with surrogate entoglossal processes that had no tapered tip and shorter with surrogate processes that had a tapered tip about four times as long as the natural entoglossus. Tetanically stimulated accelerator muscles reached 90% of peak force 110 ms after the onset of stimulation, indicating that the 185 ms delay between the onset of accelerator activity and the onset of projection seen in vivo allows the accelerator to achieve peak force prior to the onset of projection. Thus, the delay in projection may be crucial in maximizing the acceleration and velocity achieved by the projected chameleon tongue.

The Effect of Distraction upon Bone, Muscle, and Periosteum

Bone lengthening was achieved on rabbit tibias by means of callus distraction (callotasis) using a dynamic external fixator. The periosteum and the muscle fascia were labeled with metal markers; changes in position of these markers during slow progressive distraction were monitored by soft radiography. During the waiting period before commencing distraction, the periosteal markers around the osteotomy site were elevated from the bone surface by newly formed external callus. There was an apparent lag period until the periosteal reaction occurred after osteotomy. Subperiosteal callus was first formed in an uncalcified state and subsequently became calcified. As distraction began, longitudinal migration of the periosteal markers was observed. It appears that the periosteum slides over the bone cortex, mitigating local stretching of the muscle around osteotomy site. The elongation of muscle occurs throughout the muscle substance and not simply at the site of osteotomy.

A model study of muscle forces and joint-force direction in normal and dysplastic neonatal hips

Orthopaedic treatment of congenital hip dysplasia does not always give the desired result. With the present model, prediction of the effects of various treatments on the force direction in the hip joint could help to improve and select treatment (the force direction is presumed to control the collum growth direction). The model contains three-dimensional mathematical descriptions of all muscles passing the hip joint, for various degrees of femoral dysplasia, and for various hip postures. Muscles run straight or curve round some skeletal parts. Muscle forces (all isometric) are calculated from muscle mass, density, pennation angle, mean fibre length, muscle elongation, and assumed activation levels. The latter serve as parameters for optimization. Resting lengths are taken from an assumed fetal posture, and from the observed neonatal posture. Differences between force directions before and after birth, as calculated with the model, agree with collum direction changes described by von Lanz and Mayet (1953).

Elongation of Peripheral Nerve and Viscera Containing Smooth Muscle

Peripheral nerve, ureter, and small bowel will all elongate over a soft-tissue expander. Elongation of peripheral nerve serves as an effective alternative to nerve grafting both in selected clinical cases and in experimental settings. While canine ureter functions well with little morphologic change following elongation, the rabbit small bowel morphology and function are significantly altered after elongation through expansion.

Impaired ventricular relaxation during myocardial ischemia and after reperfusion in isolated perfused canine hearts.

The goal of this study was to investigate the mechanisms of impaired relaxation in ischemic and reperfused hearts without asynergic wall motion. To test the hypothesis that muscle elongation during ischemia does not improve the slowed relaxation, the time constant (T) of the isovolumic left ventricular pressure decay was obtained during volume loading in 14 isolated perfused canine hearts. In the nonischemic condition (coronary perfusion pressure: 107 +/- 3 mmHg), T progressively decreased as the peak left ventricular pressure was increased by volume loading. In contrast, in the ischemic condition (coronary perfusion pressure: 51 +/- 3 mmHg), T did not decrease despite an increase in peak left ventricular pressure by volume loading. These results indicate that during ischemia the impaired relaxation is not improved by an increase in preload. Moreover, reperfusion after a brief ischemia also increased T despite an increase in the contractile force, i.e., left ventricular pressure. The maximal change in the relaxation rate occurred much earlier than the maximal overshoot of the contractile force and coincided with an increase in coronary blood flow. These results indicate that prolongation of relaxation immediately after reperfusion is partly attributable to an increase in the electile force induced by the refilling of the coronary arteries. These mechanisms of impaired relaxation during ischemia and reperfusion may deteriorate ventricular filling and hence, cardiac output.

Muscle mechanics and pathomechanics. Their clinical relevance.

This article reviews pertinent mechanical characteristics of the human musculotendinous unit. Contractile and elastic elements of muscle are discussed, primarily in relationship to their length-tension and force-velocity properties. Evidence from a variety of recent studies of muscle function and dysfunction is presented. Clinical implications for physical therapy practice are discussed, and examples of pathological conditions are cited. A primary conclusion reached is that the degree and duration of muscle elongation are important factors in immobilization and important considerations in therapeutic programs.

The muscle elongation test in functional squints. History - basis and clinical features.

Work carried out by Cüppers has proved that squint deviations are related to the innervational and viscoelastic impairments of th ocular muscles, whose association and degree vary according to each case. The passive duction test is always positive in retraction syndromes, but it is not precise enough to detect most of the viscoelastic impairments of functional squints. The authors have noted important and frequent anomalies of muscle stretching; they describe the operative features of a muscle elongation test in various types of strabismic deviations.

The Muscle Elongation Test in Functional Esotropias

Study of the muscle elongation test in 211 patients with convergent squints who never have been operated on previously reveals that about 35% of cases display abnormal muscle stretching; 48 cases retain a lasting anesthetic angle in spite of a normal elongation test. Particularly significant correlations exist between a positive muscle elongation test and the degree of clinical oculogyric spasm, electro-oculographic motor impairments, squint deviation degrees, and age at strabismus onset. All these correlations prove that viscoelastic anomalies of the ocular muscles are secondary to supranuclear innervational impairments. In addition, both together have an asymmetrical degree on each eye in more than half the cases. The authors conclude that, in order to choose the correct surgical procedure, the results of the anesthetic and muscle elongation tests must be taken into account.

Surgical results in functional squints. Analysis and pathogenetic meaning.

(1) In functional squints, it is necessary to assess, in each case, the exact and particular role played by innervational and viscoelastic impairments by carrying out a thorough clinical examination, an electro-oculographic recording and the anesthetic and muscle elongation tests. Such as appraisal is still only approximate, however. (2) Various surgical methods permit the suppression of the deviation but all the procedures are purely empirical, and their results have no pathogenetic significance. Moreover, all the surgical actions cause some muscle and health scarring. For all these reasons, a high rate of success of one-step surgery is not possible. (3) An accurate appraisal of motor balance and, in particular, of the sensory state is very difficult. It can only be achieved by successive controls over a long period of time. Early surgery has many substantial drawbacks. The adjustable-suture technique is very tempting, but the lack of cooperation of most young children renders it use difficult.

Role of the papillary muscle in opening and closure of the mitral valve.

Dimensional changes of the left ventricular anterolateral papillary muscle of six open-chest dogs were measured continuously throughout the cardiac cycle in order to evaluate the role of the papillary muscle in opening and closing of the mitral valve. Dimensional changes were measured with ultrasonic dimension gauges. Maximal shortening and maximal elongation of the papillary muscle followed maximal shortening and elongation of a segment of the free wall of the left ventricle by 65 +/- 6 (SE) ms. Maximal elongation of the papillary muscle occurred 25 +/- 2 ms after the onset of ejection. Maximal shortening of the papillary muscle occurred 68 +/- 5 ms after the aortic incisura and 10 +/- 2 ms after the crossover of left ventricular and left atrial pressure. The papillary muscle shortened 14 +/- 4%. The percentage of papillary muscle shortening that occurred after the aortic incisura was 39 +/- 7%, and the percentage of shortening that occurred after the crossover of left ventricular and left atrial pressure was 3 +/- 1%. The observed shortening of the papillary muscle throughout left ventricular isovolumic relaxation suggests that the papillary muscle may have a role in opening the mitral valve. Conversely, elongation of the papillary muscle in the late portion of diastole appears necessary to permit proper closure of the mitral valve leaflets.

EMG, bite force, and elongation of the masseter muscle under isometric voluntary contractions and variations of vertical dimension

The relation between EMG activity, bite force, and muscular elongation was studied in eight subjects with complete natural dentition during isometric contractions of the masseter muscle, measured from 7 mm to almost maximum jaw opening. EMG was registered with superficial electrodes and bite force with a gnathodynamometer. In series 1, recordings of EMG activity maintaining bite force constant (10 and 20 kg) show that EMG is high when the bite opening is 7 mm, decreases from 15 to 20 mm, and then increases again as jaw opening approaches maximum opening. In series 2, recordings of bite force maintaining EMG constant show that bite force increases up to a certain range of jaw opening (around 15 to 20 mm) and then decreases as we approach maximum jaw opening. Results show that there is for each experimental subject a physiologically optimum muscular elongation of major efficiency where the masseter develops highest muscular force with least EMG activity.

下部尿路の尿流動態研究

A silicone gel prosthesis, reported by Kaufman in 1973 for the urinary anti-incontinence operation, has been implanted in 3 patients.Case 1: An 8-year-old boy complained of continuous dribbling of urine owing to congenital malformation of the external sphincter. The postoperative distension of prosthesis following the implantation was performed in 2 occasions with 7 ml of contrast medium. The maximum urethral pressure is presently 52mmHg and the result is good.Case 2: A 27-year-old man with a traumatic urethral rupture. The silicone gel prosthesis was implanted after transurethral resection of massive fibrosis at the posterior and bulbous urethra. The postoperative infusion of 8ml contrast medium failed to increase the maximum urethral pressure above 30mmHg. A penile clamp is necessitated; poor result.Case 3: A 42-year-old man with a traumatic urethral rupture. The sling operation at the anterior urethra was previously attempted in vain using the fascia of rectus muscle. The postoperative distension of prosthesis with 10ml of contrast medium following the implantation was not sufficient to prevent the incontinence completely. The amplitude of the maximum urethral pressure remained at 28mmHg; poor result.While the immediate postoperative results were excellent in all cases, the compression effect started to deteriorate in about one week after operation. The fall of compression strength had to be compensated by the infusion of contrast medium up to 10ml. It is speculated that the dissipation of local edema and/or elongation of ischiocavernosus muscle and Dacron-velour straps are responsible for this change. The present results, 8 to 20 months later, are 1 good and 2 poor.A thorough urodynamic investigation on the lower urinary tract should be considered for all patients before and after the operation. The urethral pressure profilometry is quite of use to evaluate both the remaining urethral sphincter function preoperatively and the strength of urethral compression attained by prosthesis postoperatively. A patient who has shown the fibrotic degeneration at the site of bulbous urethra cannot be a candidate for this operation, since the scar tissue with a high elastic constant prevents the urethral lumen to be occluded completely with this prosthesis. Urinary flowmetry and urethrocystography are also of value to investigate the functional and organic alterations caused by the implantation of prosthesis.

Effects of protein synthesis inhibitors on muscle growth in the puparium of Calliphora vomitoria

Methods are described for measuring the length and the myofibril diameter of the sixth dorsal longitudinal flight muscle of 7-, 8- and 9-day old puparia of C. vomitoria. The muscle fibres are divided up into nuclear deliminated areas and the number of myofibrils in one of these areas is found to be constant. The growth of the myofibrils in one of the nuclear deliminated areas is described. Injections of 20 μg of cycloheximide reduces amino acid incorporation into protein to 3–4% of the normal level in 7- and 8-day-old puparia. Injections of cycloheximide does not stop the elongation of the flight muscle but prevents increases in myofibril diameter. These different responses are discussed.

Some effects of low oxygen partial pressures on the development of Calliphora vomitoria

The influence of wet conditions and low pO 2 on the survival and development of non-feeding final instar larvae and puparia of Calliphora vomitoria has been investigated. The larvae delay the formation of the puparium in wet conditions in air and in dry or wet conditions in 10 and 5% oxygen. This may be related to the susceptibility of the newly formed puparia to oxygen shortage. The pupal respiratory horns play an important part in maintaining O 2 uptake when the puparia are surrounded by particles covered with a film of water but are not involved in aiding survival in low pO 2. Zero age puparia are killed by a 2 day exposure to 10% O 2 but later stages can continue to develop in this gas. Fifty per cent of the 0, 1 and 9 day old puparia are killed by about a 12 hr exposure to 1% O 2 whereas 50 per cent of the 2 to 8 day old puparia can survive over 1·5 days exposure to this gas. Development, as measured by respiration rates and the timing of the emergence of the adults, is delayed by 1% O 2 by the amount of time that the insects spend in that gas. However, the first phase of elongation of the pharate adult longitudinal flight muscle, occurring between the third and fourth day of puparial life, is only slightly slowed down in 1% O 2. The variations in susceptibility to 1% O 2 and the growth of the muscles are discussed in relation to published accounts of protein synthesis in the puparium.

THE EFFECT OF CNS DEPRESSANTS ON MITOSIS

SUMMARYDuring the last 30 years many studies have shown that most anesthetic agents in addition to some narcotics and tranquilizers interfere with normal cell division. It appears that anesthetics in the right concentration, which usually is within the range used clinically, arrest mitosis in metaphase. Metaphase block is called “c‐mitosis” since it was first seen after the application of the antimitotic poison, colchicine.The nature of “crc‐mitosis” is unknown, but a relation of known anesthetic effects to “c‐mitosis” indicates that anesthetic agents and presumably other mitotic poisons may interfere with normal aerobic metabolism by inhibiting one of two independent electron transporting systems, the “activity” respiration. The site of action seems to be one of the initial steps in the mitochondria1 electron carrier chain, maybe DPNH and its oxidase, and ascorbic acid could be intimately connected with this system.“C‐mitotic” agents interfere with the function of the mitotic spindle. Spindle contraction and elongation are likely to be similar to the contraction and elongation of general muscle and seem to depend upon different phosphagens as the source of energy. An inhibition of the “activity” respiration mentioned above may deprive the spindle of the necessary energy with spindle inactivation or destruction, i. e. metaphase block, as the result.It is discussed whether “c‐mitotic” agents are potentially teratogenic, but although there are certain indications in this direction, it is too early to give a conclusive answer. Preliminary studies suggest that anesthetic gases and vapors are teratogenic in the chick embryo.

Effect of certain cations on relaxation of the glycerol-extracted heart muscle of frogs.

Hearts of large bullfrogs ( Rana catesbiana) were extracted in 50% glycerol at –10 to –20°C. These hearts were then perfused with solutions of desired molarity, and contractions were measured by a compound lever attached to the ventricles. Perfusion was carried out with solutions containing magnesium, sodium, potassium or calcium chloride (using the molarities of these ions in Ringer's solution); the solutions were adjusted to ph 7.5 at room temperature. The salts were perfused singly or in various combinations. Ventricular contraction was induced by ATP (0.016 m, adjusted to ph 7.5) added directly to the perfusate. The data indicate that, following contraction of the hearts with ATP, the perfusion of Na, Mg and K cations enhance relaxation of the glycerinated hearts. Of these cations, the Na ion may be of particular importance in relaxation of the ATP-contracted muscle, for Na perfused alone caused a more rapid rate of muscle elongation. However, when the hearts were previously irrigated with Mg ion, perfusion with Na then provoked strikingly rapid relaxation of the glycerinated hearts. Ca ion was not observed to recontract the hearts after original ATP-contraction and relaxation by Na-Mg irrigation.