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PubMed1974

The effects of load and force on tremor at the normal human elbow joint.

1. Spontaneous flexion-extension tremor of the elbow was recorded in normal human subjects while they exerted a flexing force against different loads.2. Increases in the flexing force up to (1/2) or (3/4) of the subject's maximum were accompanied by increases in the amplitude of the tremor. A further increase to very large forces was associated with a decrease in tremor.3. When the subject flexed against a spring, the frequency of the tremor was related to the properties of the spring; with increasingly stiff springs the tremor frequency increased up to about 12 Hz. With the stiffest springs, however, the tremor became irregular and very small in amplitude.4. Weights added to the limb at the wrist reduced the frequency of tremor.5. By using appropriate combinations of spring and mass, the principal tremor frequency could be adjusted between 2 and 12 Hz, higher in some subjects. Within this range the frequency(2) was approximately proportional to the spring stiffness/mass, just as it is in a spring-mass system, though the forearm provided some of this mass, and some of the spring-like resistance was in the flexor muscles.6. When by suitable loading the tremor frequency was brought between 8 and 12 Hz, and the subject forcibly flexed his elbow, the tremor became regular and large in amplitude. This was a form of limited instability in the stretch reflex which arose because a powerful reflex response to extension of the elbow acted back on the flexor muscles after a delay.7. When the limb was so loaded that its natural frequency was outside this 8-12 Hz range, it behaved as a filter, and in response to any disturbing noise it oscillated mainly at frequencies close to the natural frequencies of either the mechanical system or the stretch reflex.8. This filtering function of the limb with its stretch reflex probably plays an important part in the control of normal movement and tremor.9. The large flexing forces that were here associated with vigorous tremor normally occur when a limb supports a large mass. Such a mass would give the mechanical system within the limb a low natural frequency; inconveniently large oscillations in the 8-12 Hz range would therefore seldom occur.

Adolescent↗
PubMed1979

Electromechanical noise in atrial muscle cells of the carp: a possible ionic feed-back mechanism.

1. Spontaneous electrical fluctuations (+/- 0.2-0.4 mV) were recorded in 'quiescent' atrial fibres of the carp. 2. The noise decreased in acetylcholine, small hyperpolarization and EGTA. 3. The noise increased (to +/- 1-2 mV) and became more synchronous in K+-free Ringer and in ouabain. 4. Large voltage fluctuations (+/- 1-2 mV) were accompanied by a fine mechanical tremor, indicating intracellular [Ca2+] fluctuations. 5. Spectral analysis showed a clear resonant frequency at about 1 Hz, indicating that the noise cannot result from the random switching of independent ionic channels. 6. We propose that the intracellular [Ca2+] and the membrane K+-conductance are involved in a feed-back loop which can oscillate and produce the electromechanical noise. The frequency of oscillation is determined by the relatively slow diffusion of Ca2+ from the intracellular reservoir to the surface membrane.

Animals↗
PubMed2005

Palisade endings in extraocular muscles of the monkey are immunoreactive for choline acetyltransferase and vesicular acetylcholine transporter.

PURPOSE: To analyze palisade endings in extraocular muscles (EOMs) of a primate species and to examine our previous findings in cat that palisade endings are putative effector organs. METHODS: Eleven monkeys (Macaca fascicularis) of both sexes, between 4 and 6 years of age were analyzed. Whole EOM myotendons were immunostained with four combinations of triple-fluorescent labeling and examined by confocal laser scanning microscopy. Labeling included antibodies against choline acetyltransferase (ChAT), vesicular acetylcholine transporter (VAChT), neurofilament, and synaptophysin. Muscle fibers were counterstained with phalloidin. RESULTS: Palisade endings were observed in all monkey EOMs. Nerve fibers extended from the muscle into the tendon and looped back to divide into a terminal arborization (palisade ending) around a single muscle fiber tip. In approximately 30% of the cases, nerve fibers supplying palisade endings often established motor terminals outside the palisade complex. Nerve fibers forming palisade endings were ChAT-neurofilament positive. Axonal branches of palisade endings were ChAT-neurofilament positive as well. All palisade nerve terminals exhibited ChAT-synaptophysin immunoreactivity. Within the palisade complex, palisade nerve terminals exhibited VAChT immunoreactivity. All palisade nerve terminals were VAChT-synaptophysin immunoreactive. CONCLUSIONS: The results confirm that in the monkey, palisade endings contain acetylcholine and are therefore most likely effector organs. Palisade endings are also present in human EOMs and because of their location at the myotendinous junction, these organs are of crucial interest for strabismus surgery.

Animals↗
PubMedDate not supplied

Electromyographic analysis of the trunk in golfers.

Golf is a popular sport for both men and women. The trunk is the most common area of injury during the golf swing. The purpose of this study was to describe and compare the muscle firing patterns in the trunk during the golf swing. Twenty-three golfers with handicaps of five or below volunteered for this study. Surface electromyographic electrodes were placed on the abdominal oblique and erector spinae muscles bilaterally. High-speed cinematography was used in conjunction with the electromyographic electrodes. The results demonstrated relatively low activity in all muscles during takeaway (below 30% of maximal muscle test), and relatively high and constant activity throughout the rest of the swing (above 30% maximal muscle test, with the exception of the contralateral erector spinae during late follow-through, which was 28% maximal muscle test). This high and constant activity demonstrated the importance of the trunk muscles during a golf swing. These results indicate the need for an effective preventive and rehabilitative exercise program for the golfer.

Abdominal Muscles↗
PubMed1993

Inadvertent intravenous administration of an elemental enteral nutrition formula.

OBJECTIVE: To report a case of intravenous infusion of an elemental enteral nutrition formula. CASE SUMMARY: A 65-year-old woman with a high-output jejunostomy required fluid and electrolyte replacement via a central line and enteral nutrition support via a gastrostomy tube. She inadvertently received 160 mL of half-strength elemental enteral nutrition formula (Vivonex TEN) via her central venous catheter. After four hours of the infusion, the patient felt ill and was found to by hypotensive and pyrexic. Over the next 24 hours she developed severe back pain and diffuse muscle tenderness. Her creatine kinase concentration was mildly elevated and there were no electrocardiographic changes. There was no rise in serum amylase concentration. Her renal function deteriorated markedly over the following three hours but responded to hydration and diuretic therapy. Liver enzymes, slightly elevated prior to this event, remained unchanged. Blood cultures were negative, but prophylactic therapy with vancomycin and ceftazidime was instituted. The patient recovered and was discharged eight days later. DISCUSSION: Previous reports of inadvertent intravenous administration of enteral feedings have described such complications as osmolarity, microembolism, hypersensitivity, and septicemia. This patient's nonfatal outcome may have been related to the infusion of the enteral formula via the central rather than the peripheral route, the infusion of an elemental rather than a whole protein formula, and the use of sterile water to reconstitute the formula. CONCLUSIONS: Particular care should be taken when a patient has more than one catheter implanted on the chest or abdomen (e.g., central venous or peritoneal dialysis catheter). It is important that inservice training is provided and written protocols are available for the safe infusion of enteral formulas.

Aged↗
PubMed2007

Oncogenic osteomalacia: exact tumor localization by co-registration of positron emission and computed tomography.

UNLABELLED: In oncogenic osteomalacia, the causative tumor is almost always difficult to find. A novel diagnostic approach is presented that facilitates a precise and rapid localization of the associated lesion by PET-CT co-registration using the radiotracer (68)Ga-DOTANOC. INTRODUCTION: Oncogenic osteomalacia (OOM) is an uncommon disorder characterized by hyperphosphaturia, hypophosphatemia, decreased vitamin D(3) serum levels, and osteomalacia. The paraneoplastic syndrome is exclusively driven by a small somatostatin receptor (sst)-positive tumor that produces phosphatonins, proteins that cause renal phosphate loss. OOM can be cured completely on tumor removal. However, the exact tumor localization is the most challenging step, because the lesion is notoriously difficult to detect by common imaging techniques. MATERIALS AND METHODS: A 60-year-old woman complained of severe pain in her back and chest wall, muscle weakness, and reduced physical activity for >1 year. She suffered a metatarsal fracture and presented with hyperphosphaturia and hypophosphatemia. OOM was suspected, and a meticulous search for the tumor was initiated by conventional imaging techniques, sst-mediated imaging using (111)In-octreotide scintigraphy, and (68)Ga-DOTANOC-based positron emission tomography (PET)-CT co-registration. (68)Ga-DOTANOC is a novel radiopharmaceutical compound in which the somatostatin analog octreotide is modified at position 3, chelated with DOTA, and complexed with (68)Gallium. (68)Ga-DOTANOC has an improved affinity to sst2 and sst5 relative to other radiopeptides. RESULTS: Whereas common imaging techniques such as CT failed to localize the tumor, (111)In-octreotide scintigraphy was able to detect the lesion, but only PET-CT using (68)Ga-DOTANOC revealed the exact tumor localization in the right femoral head. On tumor resection, the well being of the patient improved significantly, and biochemical parameters returned to normal. CONCLUSIONS: (68)Ga-DOTANOC-based PET-CT is a novel and powerful approach to detect sst-positive tumors in a timely manner and to provide highly resolved images facilitating the development of a therapeutic strategy.

Bone Neoplasms↗
PubMed2004

Pharmacological alternatives for the alleviation of back pain.

Drugs constitute a convenient option for low back pain and are commonly used. However, evidence for their efficacy is meagre. Many drugs used for back pain are no more, or only slightly more, effective than placebos. Others have side effects that outweigh their usefulness in relieving pain. On the basis of the evidence, no drug regimen can be legitimately recommended for back pain. The management of back pain requires measures other than drugs. One exception is the use of willow (Salix) bark for acute exacerbation of pain. Ironically, for chronic low back pain, the most effective and long-lasting outcomes have been documented for normal saline by injection into tender points in the lumbar spine.

Analgesics↗
PubMed2002

Aggressive exercise as treatment for chronic low back pain.

Exercise has long been a standard of treatment for back pain. Over the last 2 decades, the use of intense, non-pain-contingent exercises for treatment of chronic back pain has received increased advocacy. The main goals of these treatments are to improve functioning of painful lumbar soft tissue and to decrease the fears and concerns of patients about using their backs for daily activities. The methodology of an aggressive quota-based exercise approach to back pain is outlined in this article. This approach relies on objective quantification of physical capabilities, treatment directed at altering these parameters, and repeat quantification for determination of treatment efficacy and positive feedback. By eliminating impairments in back function, altering fears and beliefs about pain, and reducing disability, patients with chronic low back pain can achieve meaningful improvements in their quality of life.

Behavior Therapy↗
PubMed1998

Piriformis syndrome: assessment of current practice and literature review.

Although piriformis syndrome was initially described in 1928, it has remained a nebulous and controversial diagnosis. A literature review reveals that there is no consensus on the diagnosis or treatment of piriformis syndrome. In addition, a survey of 75 physiatrists revealed that whether the diagnosis of piriformis syndrome even exists is controversial. This survey and literature review examines the diagnosis and treatment of piriformis syndrome. The fact that it remains controversial is likely due to a lack of objective clinical trials.

Humans↗
PubMed2000

Piriformis syndrome.

Explore the source record for details and available documents.

Diagnosis, Differential↗
PubMed2003

3: Rehabilitation principles for treating chronic musculoskeletal injuries.

Evaluation of patients for rehabilitation after musculoskeletal injury involves identifying, grading and assessing the injury and its impact on the patient's normal activities. Management is guided by a multidisciplinary team, comprising the patient, doctor and physical therapist, with other health professionals recruited as required. Parallel interventions involving the various team members are specified in a customised management plan. The key component of the plan is active mobilisation utilising strengthening, flexibility and endurance exercise programs. Passive physical treatments (heat, ice, and manual therapy), as well as drug therapy and psychological interventions, are used as adjunctive therapy. Biomechanical devices or techniques (eg, orthotic devices) may also be helpful. Coexisting conditions such as depression and drug dependence are treated at the same time as the injury. Effective team communication, simulated environmental testing and, for those employed, contact with the employer facilitate a staged return to normal living, sports and occupational activities.

Biomechanical Phenomena↗
PubMed2003

Immobilization of North American porcupines (Erethizon dorsatum) using ketamine and xylazine.

We performed 345 immobilizations on 150 North American porcupines (Erethizon dorsatum) using a mixture of ketamine hydrochloride (KH) and xylazine hydrochloride (XH). A subsample of 184 immobilizations performed on 124 individuals from 4 May to 7 November 2000 and from 22 January to 30 April 2001 is thoroughly analyzed. In contrast to published procedures, we found that injecting drugs into tail muscles was more efficient than into longitudinal muscles of the lower back, because tail injections decreased the need of multiple injections by 26%. Using tail injections, we were able to reduce the dose by 50% from other published reports without significantly affecting induction, immobilization, standing, or recovery times. We suggest that injection of 5 mg KH/kg and 2 mg XH/kg in the tail as a standard procedure to immobilize North American porcupines. Body mass significantly affected the induction and standing times for single injections performed in the tail, irrespective of dose or sex. Sex, dose, and mass had no effect on the quality of immobilizations and the respiration rate of individuals during immobilization. We report a 0.87% mortality rate using a mixture of KH and XH and suggest ways to further decrease this rate.

Adrenergic alpha-Agonists↗
PubMedDate not supplied

[Spinal myoclonus which appeared during the administration of alpha interferon].

We report a 42-year-old man who showed myoclonus in his right leg during alpha-interferon (alpha-IFN) treatment for HCV-RNA positive chronic hepatitis C. The myoclonus continuously persisted even during sleeping. Surface EMG recordings revealed fairly regular about 0.3 Hz periodic grouping discharges synchronized in the right lower extremities muscles. Jerk-locked back averaging method demonstrated a monophasic negative sharp wave associated with the myoclonus. This pre-myoclonus sharp wave was localized on the Cz and preceded the myoclonus by about 60 ms. T 2-weighted gradient-echo MRI images revealed a high-intensity lesion in the right leg motor cortex in the left hemisphere. The myoclonus vanished in association with the disappearance of the above MRI lesion one month after the termination of alpha-IFN therapy. Based on these, we conclude the alpha-IFN may induce the myoclonus in this patient.

Adult↗
PubMed1999

[Segmentation in vertebrates: a molecular clock linked to periodic somite formation].

In the vertebrate embryo, somites constitute the basis of the segmental body pattern. They give rise to the axial skeleton, the dermis of the back and all striated muscles of the body. In the chick embryo, a pair of somites buds off, in a highly coordinated fashion, every 90 minutes, from the cranial end of the presomitic mesoderm (PSM) while new mesenchymal cells enter the paraxial mesoderm as a consequence of gastrulation. The processes leading to the segmentation of the somite are not yet understood. We have identified and characterised c-hairy1, an avian homologue of the Drosophila segmentation gene, hairy. c-hairy1 is strongly expressed in the presomitic mesoderm where its mRNA exhibits a cyclic posterior-to-anterior wave of expression whose periodicity corresponds to the formation time of one somite (90 min). Fate mapping of the rostral half of the PSM using the quail-chick chimera technique supports a model of cryptic segmentation within the presomitic mesoderm, and indicates that c-hairy1 expression dynamics are not due to massive cell displacement. Analysis of in vitro cultures of isolated presomitic mesoderm demonstrates that rhythmic c-hairy1 mRNA production and degradation is an autonomous property of the paraxial mesoderm. Rather than resulting from the caudal-to-rostral propagation of an activating signal, it arises from pulses of c-hairy1 expression that are coordinated in time and space. Blocking protein synthesis does not alter the propagation of c-hairy1 expression, indicating that negative autoregulation of c-hairy1 expression is unlikely to control its periodic expression. Most of the segmentation models proposed for somite formation rely on the existence of an internal clock coordinating the cells to segment together to form a somite. These results provide the first molecular evidence of a developmental clock linked to segmentation and somitogenesis of the paraxial mesoderm, and support the possibility that segmentation mechanisms used by invertebrates and vertebrates have been conserved.

Animals↗
PubMed1975

Fatigue fracture: the basic lesion is inthmic spondylolisthesis.

The defect in the pars interarticularis in spondylolysis and spondylolisthesis is most often the result of repeated trauma, stress, and factors other than acute fracture. These fatigue fractures develop early in life, may have a strong hereditary basis, and most often represent incidental roentgenographic findings. Attention should be given to the youngster or adolescent with low-back pain and paraspinal muscle spasm. If these patients are followed closely, the incidence of pars interarticularis defect is higher than appreciated. The lesion in some of these individuals may progress to significant vertebral slipping. If the developing defect is recognized early, treatment can be quite satisfactory.

Adolescent↗