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At least 1,423 records · Page 79Linked to original sources
PubMed1986

Accurate reinnervation of motor end plates after disruption of sheath cells and muscle fibers.

After injury, regenerating motor axons grow back to form neuromuscular junctions at the original synaptic sites on muscle fibers. The pathways they grow along consist of basement membrane, Schwann cells, and perineurium that remained after degeneration of the original axons. All the factors necessary for directing axons to the original synaptic sites persist in muscles even after disruption of myofibers. The aim of the present experiments was to determine whether structural integrity of nerve sheath cells is required for precise reinnervation in the presence and absence of muscle fiber targets. The region of innervation of the cutaneous pectoris muscle of the frog was briefly frozen to eliminate all living cells from neuromuscular junctions, intramuscular nerve bundles, and from a 1-3-mm length of the nerve trunk. Only extracellular matrices persisted within the frozen region of muscle and nerve. These consisted of the basement membrane sheaths of myofibers, of Schwann cells, and of perineurial cells and the small fragments of disrupted cells that were bound to them. In some preparations new muscle fibers developed within the basement membrane sheaths. Regenerating axons grew through the naked basement membrane sheaths of original Schwann cells, formed numerous branches, and contacted the myofibers precisely at the original synaptic sites. By 5 weeks 75% of the original synaptic sites became reinnervated; the terminals were indistinguishable from those at normal neuromuscular junctions. In contrast, preparations in which all muscle fibers were prevented from regenerating far fewer synaptic sites became reinnervated.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Lumbar paraspinal compartment syndrome. A case report with physiologic and anatomic studies.

A 24-year-old man presented with severe low-back pain and paraspinal muscle spasm after exertion. Elevation in temperature, white blood cell count, serum muscle enzymes, and urine myoglobin, as well as computer tomographic evidence of paraspinal muscle edema and necrosis, were present. No etiology could be documented, and the possibility of an acute exertional compartment syndrome was entertained. Subsequently, cadaveric dis-sections indicated that the erector spinae muscles are contained within a well-developed fascial sheath. Continuous slit catheter pressure measurements within this compartment in eight healthy male subjects were subsequently carried out. These indicated a physiologic behavior similar to other known compartments for which compartment syndromes have been described. Variation in intracompartmental pressure occurred as a function of body posture, erector spinae isometric contraction, and active intra-abdominal pressurization. We suggest this patient had a paraspinal compartment syndrome and have described pressure characteristics of this compartment in normal men.

Adult↗
PubMed2006

An electromyographic analysis of commercial and common abdominal exercises: implications for rehabilitation and training.

STUDY DESIGN: A repeated-measures, counterbalanced design. OBJECTIVES: To test the effectiveness of 7 commercial abdominal machines (Ab Slide, Ab Twister, Ab Rocker, Ab Roller, Ab Doer, Torso Track, SAM) and 2 common abdominal exercises (crunch, bent-knee sit-up) on activating abdominal and extraneous (nonabdominal) musculature. BACKGROUND: Numerous abdominal machine exercises are believed to be effective in activating abdominal musculature and minimizing low back stress, but there are minimal data to substantiate these claims. Many of these exercises also activate nonabdominal musculature, which may or may not be beneficial. METHODS AND MEASURES: A convenience sample of 14 subjects performed 5 repetitions for each exercise. Electromyographic (EMG) data were recorded for upper and lower rectus abdominis, external and internal oblique, pectoralis major, triceps brachii, latissimus dorsi, lumbar paraspinals, and rectus femoris, and then normalized by maximum muscle contractions. RESULTS: Upper and lower rectus abdominis EMG activities were greatest for the Ab Slide, Torso Track, crunch, and Ab Roller, while external and internal oblique EMG activities were greatest for the Ab Slide, Torso Track, crunch, and bent-knee sit-up. Pectoralis major, triceps brachii, and latissimus dorsi EMG activities were greatest for the Ab Slide and Torso Track. Lumbar paraspinal EMG activities were greatest for the Ab Doer, while rectus femoris EMG activities were greatest for the bent-knee sit-up, SAM, Ab Twister, Ab Rocker, and Ab Doer. CONCLUSIONS: The Ab Slide and Torso Track were the most effective exercises in activating abdominal and upper extremity muscles while minimizing low back and rectus femoris (hip flexion) activity. The Ab Doer, Ab Twister, Ab Rocker, SAM, and bent-knee sit-up may be problematic for individuals with low back pathologies due to relatively high rectus femoris activity.

Abdominal Muscles↗
PubMedDate not supplied

[Effect of heterogeneity of the myocardium on its mechanical function].

The influence of the mechanical heterogeneity on the myocardium contractility was evaluated. The heterogeneity was imitated by parallel connection of two papillar muscles with different mechanical properties. The rate of muscle shortening was controlled by a feed-back from tension of each of the muscles or both muscles simultaneously in the precision ergometer. The "force-velocity" and "length-force" relations were registered for each muscle independently, and in case of parallel connection of two muscles. It was shown that connection of two muscles in parallel influenced significantly the distribution of load in the muscles, maximal and mean velocity of their shortening. It is stated that the key phenomenon controlling the value and the heterogeneity influence sign is mechano-chemical uncoupling (inactivation).

Animals↗
PubMedDate not supplied

Long-term results of hang-back medial rectus recession.

PURPOSE: To report long-term results with the hang-back technique for medial rectus muscle recession. METHODS: Medical records of 341 consecutive patients who underwent unilateral or bilateral hang-back medial rectus recession were reviewed. The amount of recession was based on the size of the esotropia as measured at near fixation. Patients were divided into two groups according to age at onset of esotropia: patients <1 year comprised group 1 and patients > or = 1 year comprised group 2. Surgical outcomes were analyzed for all patients included in the study. RESULTS: A total of 189 patients met the inclusion criteria. In group 1 patients (n=32), average deviation improved from 48.3 prism diopters (PD) preoperatively to 1.1 PD postoperatively. Eleven patients required a second procedure: 9 with recurrent esotropia and 2 with consecutive exotropia. Average time to second procedure was 27.4 months. In group 2 patients (n=157), average deviation improved from 29.6 PD preoperatively to 1.1 PD postoperatively. Twenty-one patients required a second procedure: 20 with recurrent esotropia and 1 with consecutive exotropia. Average time to second procedure was 22.7 months. CONCLUSION: The hang-back technique represents a safe, effective alternative to conventional medial rectus recession.

Esotropia↗
PubMed1996

Loss of the position-dependent reinnervation of regenerated toad (Bufo marinus) glutaeus muscle.

The terminations of motor axons in the toad glutaeus muscle show a course dependency on the segmental origins of the axons on the spinal cord. Rostral axons in spinal nerve 8 innervate muscle fibres near the ventral surface of the muscle, while caudal axons in spinal nerve 9 innervate fibres mostly towards the opposing dorsal surface. Axons originating between these extremes tend to innervate the central regions of the muscle. A similar topographic projection is reestablished after denervation and when regenerating axons reinnervate the muscle via entirely novel pathways (Brown and Everett [1991] J. Comp. Neurol. 309:495-506). The findings are compatible with the graded expression of a determinant within the glutaeus muscle that biases the formation of synapses between positionally matched muscle fibres and motor axons. In the present work, we provide strong support for this view by showing that when the muscle is reinnervated by axons arising from only one spinal nerve, they expand their projection and form synapses in the muscle in a topographically appropriate manner. In a second experiment, we tested whether a muscle that had regenerated from its resident myogenic (satellite) cell population would be similarly reinnervated. This experiment was prompted by the work of others (Donoghue et al. [1992] Cell 69:67-77) showing that the myogenic precursor cells in adult muscle are a repository of "positional memory." In our experiments, a glutaeus muscle was removed from adult toads and soaked in bupivacaine for a brief period to destroy the muscle fibres before being sutured back into its normal position in the limb. The distribution of motor units in the muscles was determined by glycogen depletion after allowing 3-4 months for the muscles to regenerate from their satellite cell population and to become reinnervated. We found that muscle fibres belonging to single motor units were dispersed widely in the regenerated muscles and showed no topographic organisation. We conclude that the positional cues that direct topographic map formation are available to motor axons when they reinnervate a denervated mature muscle, but play no role in the reinnervation of a regenerated muscle.

Animals↗
PubMed2001

Perturbed upper limb movements cause short-latency postural responses in trunk muscles.

Addition of a load to a moving upper limb produces a perturbation of the trunk due to transmission of mechanical forces. This experiment investigated the postural response of the trunk muscles in relation to unexpected limb loading. Subjects performed rapid, bilateral shoulder flexion in response to a stimulus. In one third of trials, an unexpected load was added bilaterally to the upper limbs in the first third of the movement. Trunk muscle electromyography, intra-abdominal pressure and upper limb and trunk motion were measured. A short-latency response of the erector spinae and transversus abdominis muscles occurred approximately 50 ms after the onset of the limb perturbation that resulted from addition of the load early in the movement and was coincident with the onset of the observed perturbation at the trunk. The results provide evidence of initiation of a complex postural response of the trunk muscles that is consistent with mediation by afferent input from a site distant to the lumbar spine, which may include afferents of the upper limb.

Abdominal Muscles↗
PubMed1989

[Human selenium deficiency during total parenteral nutrition support (a case report)].

There is accumulating evidence that selenium plays an important role in human nutrition. We have seen an increasing number of reports of selenium deficiency in patients after long-term Total Parenteral Nutrition (TPN) support, such as Home Parenteral Nutrition support. There had been no such patient reported in China until now. A sever multiple gastro-intestinal external fistulae patient was admitted in early Oct. 1985. His intestinal fluid loss was about 4-6 liters/day and he was a resident of a town where many people have low serum selenium levels. After two weeks of high calorie, high nitrogen TPN support, his serum selenium levels were 7.14, 6.25, and 7.97 micrograms/L (around the 3rd and 4th weeks of such TPN support). The patient also showed a higher heart rate and pain in the thigh muscle. After 4 weeks of selenium supplement, his serum selenium levels and heart rate were back to normal and the muscle pain disappeared.

Adolescent↗
PubMed1981

Tenotomy of the avian anterior latissimus dorsi muscle. II. Can regeneration from the stump occur in the pigeon?

Because the chick's anterior latissimus dorsi muscle (ALD) regenerates a fast-twitch muscular connection after tenotomy, the pigeon's ALD was tenotomized, either at the origin or through the muscle 0.5 cm from the origin, to determine whether this muscle behaves similarly to the chick muscle. These procedures were compared in pigeons operated upon at 7 weeks, versus 5 to 9 months of age. The pigeon's ALD did not regenerate a new connection, and other differences were observed between the pigeon and chick ALD. The pigeon ALD has only a single slow muscle-fiber type, has fewer fast fibers, and transforms to a fast-twitch muscle more readily than the chick ALD after tenotomy. The transformation of muscle fiber types occurred more readily in the older pigeons than those tenotomized at 7 weeks of age. Tenotomy induced morphological alterations of the muscle fiber structure in all of the pigeons, which is in contrast to the absence of changes in the tenotomized chick ALD. Therefore the pigeon and chick ALD respond completely differently to tenotomy.

Adenosine Triphosphatases↗
PubMed2003

Acupuncture for chronic low back pain in older patients: a randomized, controlled trial.

OBJECTIVE: To determine if acupuncture is an effective, safe adjunctive treatment to standard therapy for chronic low back pain (LBP) in older patients. METHODS: The inclusion criteria for subjects were: (i) LBP > or =12 weeks and (ii) age > or =60 yr; the exclusion criteria were (i) spinal tumour, infection or fracture and (ii) associated neurological symptoms. The subjects were randomized to two groups. The control group of subjects continued their usual care as directed by their physicians, i.e. NSAIDs, muscle relaxants, paracetamol and back exercises. Subjects in the acupuncture group in addition received biweekly acupuncture with electrical stimulation for 5 weeks. Outcome was measured by the modified Roland Disability Questionnaire (RDQ) at weeks 0, 2, 6 and 9. The primary outcome measure was change in RDQ score between weeks 0 and 6. RESULTS: Fifty-five patients were enrolled, with eight drop-outs. Twenty-four subjects were randomized to the acupuncture group and 23 were randomized to the control group. Acupuncture subjects had a significant decrease in RDQ score of 4.1 +/- 3.9 at week 6, compared with a mean decrease of 0.7 +/- 2.8 in the control group (P = 0.001). This effect was maintained for up to 4 weeks after treatment at week 9, with a decrease in RDQ of 3.5 +/- 4.4 from baseline, compared with 0.43 +/- 2.7 in the control group (P = 0.007). The mean global transition score was higher in the acupuncture group, 3.7 +/- 1.2, indicating greater improvement, compared with the score in the control group, 2.5 +/- 0.9 (P < 0.001). Fewer acupuncture subjects had medication-related side-effects compared with the control group. CONCLUSIONS: Acupuncture is an effective, safe adjunctive treatment for chronic LBP in older patients.

Acupuncture Analgesia↗
PubMed2006

Age-related changes in the distribution of lean fat with skin and bones in goose carcasses.

The experimental materials comprised White Italian geese (128 males and 128 females) reared to 14 wk of age. The birds were fed standard diets ad libitum. Starting from 2 wk of age, 14 males and 14 females were killed at 2-wk intervals. The carcasses were divided into neck, wings, legs, breast, and back, which were then dissected into muscle, skin with fat, and bones. Before slaughter, the BW of males and females were 6,814 and 5,736 g, respectively. At 2 wk of age, more than half of total muscle content was in the legs (60.98%), and the rest was in the back (17.84%), neck (9.43%), breast (8.78%), and wings (2.97%). To 10 wk of age, the rate of muscle deposition was relatively slow in the legs (a decrease to 31.29%) and fast in the breast and wings (an increase to 34.12 and 12.90%, respectively). Age-related changes in the distribution of skin with fat in the carcass were smaller, compared with changes in muscle distribution. A rising tendency was observed in the muscle content of wings and breast and in the content of skin with fat in the wings and neck, whereas a falling tendency was observed in the other carcass parts. Over the first 8 wk, the proportion of bones decreased in the legs, back, and neck and increased in the wings and breast, as compared with the total bone weight in the carcass.

Adipose Tissue↗
PubMed2003

Paraspinal muscle denervation, paradoxically good lumbar endurance, and an abnormal flexion-extension cycle in lumbar spinal stenosis.

STUDY DESIGN: A descriptive study was conducted to investigate the paraspinal muscle function in patients with lumbar spinal stenosis. OBJECTIVE: To evaluate paraspinal muscle innervation and endurance in lumbar spinal stenosis. SUMMARY OF BACKGROUND DATA: Abnormal lumbar paraspinal muscle function is associated with chronic low back pain. Abnormal neurophysiologic findings of the lower limbs often are observed in lumbar spinal stenosis, and abnormal lumbar function also can be expected. However, paraspinal muscle function and innervation have not been studied in lumbar spinal stenosis. METHODS: The study evaluated 25 patients with clinically and radiologically diagnosed lumbar spinal stenosis. Electromyography of the paraspinal muscles was performed from L3 to S1 bilaterally using a concentric needle. At least 20 insertions were analyzed from each muscle. The aim of the examination was to detect abnormal spontaneous activity associated with axonal damage (fibrillation potentials, positive sharp waves, and complex repetitive discharges). Paraspinal muscle activity during trunk flexion-extension movement and muscle endurance during the dynamic isoinertial back endurance test were assessed by surface electromyography. Muscle fatigue was calculated using mean power frequency analysis. RESULTS: Abnormal findings in needle electromyography of the paraspinal muscles were observed in 18 of the 22 (81.8%) examined patients. Abnormal flexion-extension activation of the paraspinal muscles was observed in all the examined patients. The change in mean power frequency was significantly smaller than in previously evaluated healthy subjects and patients with nonspecific chronic low back pain (P < 0.001) who were not experiencing symptoms of lumbar spinal stenosis. Paraspinal muscle fatigability was not associated with the denervation of the muscles. CONCLUSIONS Denervation and abnormal activation of lumbar paraspinal muscles are frequent findings in patients with lumbar spinal stenosis who have not undergone surgery. The paraspinal muscle endurance of the patients was unexpectedly good.

Adult↗
PubMed1986

Physiological adaptation to physical conditioning. Old problems revisited.

Three classical problems in the field of man's adaptive response to exercise are reviewed. A case is made for the pump capacity of the heart limiting maximal oxygen uptake in man. This conclusion is based on findings that the capacity of skeletal muscle of man markedly surpasses that of the heart supplying it with a flow and thereby oxygen. It is suggested that only one third of the muscle mass of man can fully tax the capacity of the heart and consume the oxygen delivered by the heart. If a larger muscle mass is intensely engaged in the exercise, vasoconstriction must occur in the arterioles of the exercising limbs to avoid a reduction in blood pressure. Evidence is presented that a decrease in heart rate at submaximal exercise-observed after a period of physical conditioning, is caused by an altered autonomic chronotropic activity to heart, which most likely is due to a less potent feed back reflex from exercising muscles. The enlarged stroke volume is secondary to a larger diastolic filling, which via a Frank-Starling mechanism results in an elevation in the stroke volume. Last, it is argued that the altered metabolic response to exercise after physical conditioning, i.e. the larger lipid oxidation and reduced lactate production, results from local regulatory mechanisms rather than from changes in supply of oxygen, substrates, or hormones. Further, the muscle metabolic response to exercise is thought to play a major role in modulating systemic cardiovascular regulation in exercise.

Adaptation, Physiological↗
PubMed2005

[<< Reverse >> latissimus dorsi musculocutaneous flap: anatomic study of the secondary pedicles].

PURPOSE: The latissimus dorsi flap based on the secondary segmental vessels, wich is termed << reverse >> or << distally based >> latissimus dorsi flap, has been used to repair major thoraco-lumbar defects, to close myelomeningoceles and to reconstruct congenital diaphragmatic absences. The arc of flap rotation is markedly restricted because the blood supply is segmental. It is the most important factor that limits the flap mobility and so restricts its use. The authors report an anatomic study of these secondary pedicles in order to improve the flap dissection and to extend the arc of flap rotation. MATERIAL AND METHOD: The precise location of the secondary pedicles of the flap was determined by 24 anatomic dissections. RESULTS: The latissimus dorsi has 3, 4 or 5 secondary pedicles respectively in 50%, 25% and 25% of cases in the study. These pedicles take origin from the dorsal branches of the posterior intercostal arteries of the 7th, 8th, 9th, 10th and 11th intercostal spaces. CONCLUSION: The number of secondary pedicles is not constant. The entire flap can be safely based on 2 secondary pedicles when the latissimus dorsi muscle has 3 secondary pedicles. When this muscle has 4 or 5 secondary pedicles, the entire flap should be at least based on 3 secondary pedicles, particularly if the skin island is very far from the origin of these vessels.

Back↗
PubMed2005

Effect of floor slope and load carriage on standing posture.

Posture has been linked to low back pain and other ailments. While heeled shoes have been investigated, the effect of floor slope and load carriage on posture has received little attention. Therefore, the goal of this investigation was to assess these factors. Twenty-one men and 22 women (all healthy) of college age provided university-approved informed consent prior to participation. After familiarization, subjects stood motionless on the slope (facing up and down at 10 degrees and 20 degrees as well as the level), then bent over picking up a milk crate from the floor (men = 25kg, women = 15kg), and returned to a motionless standing position with the crate at knuckle height. Six trials were performed in each condition with the last three averaged to produce representative results in both standing conditions for each slope. Right sagittal plane kinematics and surface EMG of the erector spinae and middle trapezius were recorded. A static inverse model calculated moments at L5/S1. Significant differences (p < 0.001) between standing with and without the load were observed in all variables (torso, hip, knee, and ankle angles, L5/S1 moment, and both muscle activities) except low back curvature (p = 0.217). Across the floor slopes, significant trends existed in the low-back, knee, and ankle angles when standing without the load (p < 0.001) while the same parameters plus hip angle and L5/S1 moment were significantly different across floor slope with the load (p < = 0.026). In conclusion, both floor slope and load carriage should be considered when assessing ergonomic factors related to standing posture.

Adaptation, Physiological↗
PubMed2005

Spinal epidural abscess: an analysis of 24 cases.

BACKGROUND: Despite advances in neuroimaging and neurosurgical care, spinal abscess remains a challenging problem with mortality rates ranging from 4.6% to 31% in recent series. METHODS: Between January 1986 and December 2003, 24 patients with spinal epidural abscess were treated. Seventeen were men and 7 were women at the average age of 47.5 years. Concurrent illnesses that result in immunodepression such as diabetes and infections occurred in 62% of the case patients. All patients had back pain, 16 had muscle weakness, 9 had paresthesias, and 8 had sphincteral changes. Twenty-one patients underwent surgical procedures. In 11 case patients, the abscess had a frankly purulent material, and, in 5, the epidural lesion consisted of granulation tissue; the other 5 case patients had a combination of the 2. Three patients were treated conservatively. Staphylococcus aureus was isolated in 57% of the case patients. The lumbar spine was affected in 11 patients; the cervical spine, in 3. RESULTS: Fifteen patients recovered their normal neurological functions but 4 remained with some neurological disability. No deaths occurred in this series. CONCLUSIONS: Immediate surgical drainage of the abscess, before the development of severe neurological deficit, combined with specific antibiotics remains the treatment of choice.

Adolescent↗
PubMedDate not supplied

Metabolic basis for the management of patients undergoing major surgery.

After reviewing our current knowledge of the metabolic response to major abdominal surgery, we present two new studies in which we have followed the changes in body composition, physiologic function, and psychological function for up to 1 year after major surgery. In the first study, 46 patients had changes in body composition, physiologic function, and psychological function measured perioperatively and again at intervals up to 1 year. There was an average loss of weight of 3000 grams (maximum at 2 weeks), and the tissue composition of this weight loss was composed of 1400 grams fat, 600 grams protein, and 1000 grams water. Normal body composition had returned to normal in most patients by 6 months. In the second study of 84 patients, deficits of skeletal muscle function and fatigue were found to be greatest at postoperative day 7. Most patients were back to preoperative levels of muscle function and fatigue 30 days after surgery, and nearly all had normal values 90 days after surgery. Based on these studies we outline our management program for the metabolic care of patients undergoing major abdominal surgery.

Adult↗