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At least 1,297 records · Page 72Linked to original sources

PubMed2006

Disturbance of rapid eye movement sleep in spinocerebellar ataxia type 2.

Five genetically confirmed spinocerebellar ataxia type 2 (SCA2) patients were admitted to our sleep laboratory for two all-night video-polysomnographies. A standard montage was used, including electroencephalography, vertical and horizontal electrooculography, electromyography of mental, submental, and tibialis anterior muscles, and respiratory monitoring. Four of five SCA2 patients had insufficient muscle atonia during rapid eye movement (REM) sleep. All patients exhibited myoclonic jerks during REM sleep, while elaborated behavior was not observed in the video. Abnormal motor control during sleep with periodic leg movements and REM sleep without atonia occurs frequently in SCA2. This finding may reflect a dysfunction of dopaminergic and/or brainstem and cerebellar outflow pathways.

Adult↗

PubMed2004

Postural rhythmic muscle bursting activity in Angelman syndrome.

Postural impairment is one of the most consistent features of Angelman syndrome. Using multiple-channel electromyography, we studied a lower limb and an upper limb isometric postural task in 14 patients with Angelman syndrome and 18 unimpaired control subjects. Both tasks were associated with synchronous bursts of activity at frequencies of 6-8 s(-1) in all recorded muscles in all patients with Angelman syndrome and none of the control subjects. This pattern was not altered by extra-loading. Electroencephalogram recorded during the upper limb task showed no change in relation to the task. Burst-locked back-averaging of the electroencephalogram showed no spiking before or during the bursts. Various physiological and pathological rhythmic muscle activities have been proposed to be a manifestation of oscillations in the central nervous system and it has been suggested that such oscillations may have a role in the processing of motor commands. The mechanism of the rhythmic muscle bursting activity associated with maintaining posture in patients with Angelman syndrome is not clear, although it could be consistent with cerebellar Purkinje cell dysfunction, either as a pathological feature or as an adaptive process to overcome deficits in motor coordination.

Action Potentials↗

PubMed2003

Development of an experimental system for the study of urethral biomechanical function.

Despite its principal mechanical function in the storage and release of urine, the biomechanical properties of the urethra have remained largely unexplored. The purpose of this study was to develop and validate an experimental model that can be used for evaluating whole urethral tissue in such a manner. Bladder-urethral specimens were excised from halothane-anesthetized female rats and mounted at in vivo length within the experimental apparatus consisting of a tissue perfusion chamber, an adjustable fluid column, and a laser micrometer. Outer diameter measurements were made at proximal, mid, and distal axial locations in response to increases in intraluminal pressure and after addition of various muscle-responsive agents. Basal smooth muscle tone and regional variations in compliance were detected through pressure-diameter responses. Chemically evoked contractile responses were measured and correspond to regional compositions of intrinsic smooth and striated muscle components. The results presented illustrate the utility of this system, which should permit a more thorough characterization of structure-function relationships and urethral biomechanical function in relation to normal and dysfunctional tissue states.

Acetylcholine↗

PubMed2001

[Proximal muscle weakness, depressed tendon reflexes and autonomic dysfunction: the Lambert-Eaton myasthenic syndrome].

Three patients with Lambert-Eaton myasthenic syndrome (LEMS), two men aged 61 and 64 and a woman aged 55 years, all developed proximal weakness, depressed tendon reflexes and autonomic dysfunction. Although this clinical triad is highly suggestive for LEMS, the disorder had not been recognized initially. The woman had a small-cell bronchial carcinoma, treated successfully by chemotherapy, whereafter the LEMS symptoms gradually disappeared. The first man was treated with 3,4-diaminopyridine and azathioprine, whereupon his symptoms diminished. The other man had only slight complaints and refused drug treatment. The three cases illustrate that presentation and course of LEMS can vary between patients. Furthermore, clinical and electrophysiological features can suggest myasthenia gravis, myopathy or axonal polyneuropathy. Therapeutic options and the risk of underlying malignancy make early diagnosis important. In conclusion, in every patient presenting with unexplained proximal weakness, LEMS should be considered, especially if depressed tendon reflexes and autonomic dysfunction are found as well.

Autonomic Nervous System↗

PubMed2001

Selective microvascular dysfunction in mice lacking the gene encoding for desmin.

The intermediate filament desmin has a key role in the integrity and contractility of skeletal and cardiac myocytes. Its absence or aggregation leads to cardiomyopathies. In arteries desmin is distributed heterogeneously; vascular disorders might also occur in its absence. We studied endothelial and muscular functions in arteries from mice lacking desmin (des-/-), compared with control (des+/+). Carotid and mesenteric resistance arteries were mounted in vitro in arteriographs. Desmin was located exclusively in smooth muscle cells. In arteries from des-/- mice, pressure-induced (myogenic) tone was unchanged, but agonist-induced tone decreased in resistance arteries (no change in large arteries). Flow (shear stress)- and acetylcholine-induced, endothelium-dependent dilation, as well as endothelium-independent dilation, were also decreased in resistance arteries. To our knowledge, this is the first study of vascular contractile and dilatory functions in arteries lacking desmin. Although vascular reactivity was normal in large arteries, it decreased strongly in small resistance arteries. Thus, desmin is required in vascular smooth muscle cells and in resistance arteries, for efficient control of vascular tone and consequently for an optimal blood flow supply. This microvascular defect found in the absence of desmin might play a major role in myopathies seen in desmin-related diseases.

Animals↗

PubMed2003

Motor evoked potentials from the striated urethral sphincter and puborectal muscle: normative values.

AIMS: Transcranial magnetic stimulation enables the study of corticospinal motor pathways through evoked potential testing. By separate stimulation of cortical centers and spinal roots, it is possible to test motor conduction times segmentally. This method enables the localization of central or peripheral demyelinating neuropathies. As lower urinary tract dysfunction often accompanies these diseases, we wanted to present normative data for the motor innervation of the external urethral sphincter (EUS) and the puborectal muscle (PR). METHODS: Thirty healthy women without evidence of neurologic or lower urinary diseases were studied. They had a mean age of 52 years. Transcutaneous magnetic stimulations were applied to the vertex, the upper lumbar spine, and the sacrum. Evoked potentials were recorded with concentric needle electrodes placed in the EUS and the PR by a transvaginal route. Stimulations were performed with relaxed pelvic floor and with tonic contraction (facilitated responses). At least three responses were recorded for each modality. Stepwise multiple regression analysis was performed to test for the effect of age, height, body mass index, vaginal parity, and menopause. RESULTS: In some subjects, it was only possible to record cortical latencies with facilitation. Technical difficulties were encountered with spinal stimulations. Reference values are presented as means with 95% confidence intervals. Regression analysis revealed height as a dependent factor for sacral latencies. CONCLUSIONS: Our data can serve as reference values for future studies of the fast conducting fibers in patients with sphincter dysfunction. The height of the patient should be taken into account. The clinical applicability of the method is questionable.

Adult↗

PubMed1995

Irritable bladder syndrome in an animal model: a continuous monitoring study.

Irritable bladder syndrome (IBS) was induced in four female African green monkeys (Cercopithecus aethiops) by the use of intravesical instillation of acetone. The animals were housed in a modified metabolic cage for continuous micturition monitoring, and two uroflowmeters connected to a remote PC monitored the frequency, voided volumes, and peak flows. Before and after, urea absorption studies and urodynamics were obtained for each animal. Urea absorption increased significantly after acetone instillation and returned to baseline after 4 weeks (26 to 66 to 32%). Intravesical acetone instillation produced marked effects on bladder physiology in the first week. Bladder compliance dropped from a baseline of 10.47 to 0.58 ml/cm H2O. The voiding pattern changed from a normal pattern with a mean voided volume of 17.58 ml into marked increase in frequency and dribbling pattern with few voids (mean = 5.03 ml). Systematic behavioral observations were carried out for 4 hours per day utilizing an observation program on a laptop computer. Activity patterns, attention, sterotypic behaviors, and self-directed activities were recorded for each monkey. The animals demonstrated decreased frequency of activity and increased frequency in self-directed activities (groom, scratch), behaviors consistent with an animal experiencing pain or discomfort. The findings suggested that IBS induction in monkeys is feasible and produces a clinical picture similar to interstitial cystitis in humans. It offers a suitable animal model to enhance the understanding of voiding dysfunction with its neural pathways and to test the different therapeutic modalities to control IBS.

Acetone↗

PubMed2005

Racial differences in pelvic morphology among asymptomatic nulliparous women as seen on three-dimensional magnetic resonance images.

OBJECTIVE: Compare pelvic morphology between asymptomatic African-American and white nulliparous women. STUDY DESIGN: Resting supine T2-weighted magnetic resonance (MR) images were obtained in 12 African-American (AA) and 10 white American (WA) women without pelvic floor dysfunction. Three-dimensional models were reconstructed from the MR images by a masked investigator, and predefined bony and soft tissue pelvic floor parameters were measured and compared. Nonparametric statistics were used, with significance considered at P < .05. RESULTS: Subjects were similar in age and body mass index. Levator ani volume was significantly greater in the AA versus the WA group (mean = 26.8 vs 19.8 cm3, P = .002). The levator-symphysis gap was smaller in the AA (left-18.2, right-18.8 mm) versus the WA group (22.4, 22.6 mm, P = .003, .048) on the left and right. Significant differences were seen in bladder neck position, urethral angle, and the pubic arch angle. CONCLUSION: The increased muscle bulk and closer puborectalis attachment seen among the African-American nulliparous women may impact the development of pelvic floor dysfunction. These findings need further study.

Adult↗

PubMed2005

Chemo- and ergoreflexes in health, disease and ageing.

The chemo- and ergoreflexes (muscle receptors) are among the major reflex arches, which adapt the respiratory and the cardiovascular system to the needs of the body and contribute to its homeostasis. The present paper reviews the interplay of these reflexes with other major cardiovascular reflex arches; the methods used for their calculation and their normal range data. The clinical implications of chemoreflex sensitivities and ergoreflexes in chronic heart failure (CHF) as well as the application of chemoreflexes in coronary artery disease, sudden cardiac death and multiple organ dysfunction syndrome are discussed.

Aging↗

PubMed1999

Knee joint forces during isokinetic knee extensions: a case study.

OBJECTIVE: To describe the procedures to obtain knee joint forces during isokinetic knee extensions and evaluate the patellar ligament force, quadriceps tendon force, patellofemoral and tibiofemoral joint forces at different speeds measured from a female subject. DESIGN: A technical note with a case study. BACKGROUND: Two previous studies examined knee joint forces during isokinetic knee extension using different techniques reported inconsistent findings. Also, the highest speed used in these two studies (180 degrees s(-1)) were much lower than the maximum speeds available in modern isokinetic dynamometers. METHODS: The subject performed maximum effort isokinetic knee extensions at 16 different speeds ranged from 25 to 400 degrees s(-1). The gravitational and inertial effects were included in determining the resultant knee torque. Knee radiographs were used to determine the knee joint geometry. A combination of knee torque and geometric data was used to determine different knee joint forces. RESULTS: All knee joint forces were found to decrease with increasing isokinetic speed. The tibiofemoral shears forces indicated that the anterior cruciate ligament was loaded throughout the range of motion. CONCLUSIONS: The magnitudes of knee joint forces are largely depending on the knee torque values. RELEVANCE: Isokinetic knee extensions are considered appropriate for the early part of the rehabilitation for patients with knee dysfunctions due to the lesser demand of coordination. However, to reduce the knee joint forces, submaximal efforts at lower speeds or maximal efforts at higher speeds are recommended.

Adult↗

PubMed2002

A transcranial magnetic stimulation study of inhibitory deficits in the motor cortex in patients with schizophrenia.

It has been proposed that inhibitory deficits play a crucial role in the pathophysiological process of schizophrenia as suggested by post-mortem, neuropsychological and neurophysiological evidence. We hypothesised that patients with schizophrenia would demonstrate abnormalities of cortical inhibition in the motor cortex with single and paired pulse transcranial magnetic stimulation (TMS). Patients with DSM-IV schizophrenia (n=22) and normal volunteers (n=21) participated in the study. Electromyographic recordings from the abductor pollicis brevis (APB) muscle were made during focal TMS stimulation to the contra-lateral motor cortex. The threshold intensity to produce a motor response, the size of the motor evoked potential, the duration of the silent period, and the cortical inhibition and facilitation to paired pulse TMS were measured. The patient group demonstrated a reduction in length of the silent period and a reduction in cortical inhibition with paired stimuli. No changes were found in motor threshold, motor evoked potential size, or cortical facilitation. The study demonstrated deficits of cortical inhibition in the motor cortex of patients with schizophrenia. These deficits appear to be of cortical origin. Their relationship to dysfunction in other cortical networks requires further elucidation.

Adolescent↗

PubMed2000

Resistance of extraocular motoneuron terminals to effects of amyotrophic lateral sclerosis sera.

In sporadic ALS (s-ALS), axon terminals contain increased intracellular calcium. Passively transferred sera from patients with s-ALS increase intracellular calcium in spinal motoneuron terminals in vivo and enhance spontaneous transmitter release, a calcium-dependent process. In this study, passive transfer of s-ALS sera increased spontaneous release from spinal but not extraocular motoneuron terminals, suggesting that the resistance to physiologic abnormalities induced by s-ALS sera in mice parallels the resistance of extraocular motoneurons to dysfunction and degeneration in ALS.

Adult↗

PubMed2000

Recurrent Merkel cell carcinoma of the upper extremity.

We report a case of recurrent Merkel cell carcinoma (MCC) of the upper extremity, treated aggressively with wide local excision, regional lymphadenectomy, and immediate reconstruction. Five years after surgery, there is no clinical or diagnostic evidence of locoregional recurrence or distant disease. The patient's upper extremity and hand remain fully functional, without evidence of median or ulnar nerve dysfunction. No donor site morbidity has been noted.

Aged↗

PubMed2004

[Role of nitric oxide and mitochondrial permeability pore in changes of oxygen consumption in the working skeletal muscle].

On anaesthetized dogs the role NO and mitochondrial permeability transition pore (MPTP) in the regulation of regional blood circulation, efficiency of oxygen using, and muscle contraction force was investigated. Under different frequency stimulation it was shown, that short-term (30") smoothly tetanic contraction (40 Hz) is more economic for a skeletal muscle than short-term (30") single contractions (8 Hz) with respect to the efficiency of oxygen using. Injection NOS inhibitor L-NMMA (2.7 mg/kg, i.a.) resulted in pronounced fall of a functional hyperemia magnitude (P < 0.01), significant reduction of the muscle contractions force (P < 0.01), and efficiency of oxygen using (P < 0.01), in m.gastrocnemicus, in comparison with control. Pretreatment with an exogenous activator of MPTP phenilarsine oxide (PAO, 0.2 mg/kg, i.a.) caused a marked inhibition of an endothelium-dependent vessels dilation on skin-muscle region of rear limb. At the same time the muscle contractions force was significantly decreased (P < 0.01) and efficiency of oxygen using was diminished too (P < 0.01). This was accompanied by an appearance in blood from v. femoralis mitochondrial factor (MF), indicating MPTP activation. Preliminary injection of the exogenous NO donor sodium nitroprusside (0.2 mg/kg, i.v.) prevented considerably an inhibition of a dilation vessels reserve, a fall of muscle contractions force (P < 0.01) and considerably reduced oxygen cost (P < 0.01) of a m.gastercnemicus work also. The concentration of MF in blood from v. femoralis also was considerably reduced (P < 0.001) that has been the evidence of MPTP inhibition. Thus, activation of MPTP and development of oxidative stress resulted in endothelium dysfunction, a force of muscle contraction diminishing and a significant decrease in efficiency of oxygen using. NO essentially reduced the negative effects of MPTP activation and was antagonist of oxidative damages development.

Animals↗

PubMed2007

Supplemental oxygen and muscle metabolism in mitochondrial myopathy patients.

Patients with mitochondrial myopathy (MM) have a reduced capacity to perform exercise due to a reduced oxidative capacity. We undertook this study to determine whether skeletal muscle metabolism could be improved with oxygen therapy in patients with MM. Six patients with MM and six controls, matched for age, gender and physical activity, underwent (31)P-magnetic resonance spectroscopy ((31)P-MRS) examination. (31)P-MR spectra were collected at rest and in series during exercise and recovery whilst breathing normoxic (0.21 O(2)) or hyperoxic (1.0 O(2)) air. At rest, MM showed an elevated [ADP] (18 +/- 3 micromol/l) and pH (7.03 +/- 0.01) in comparison to the control group (12 +/- 1 micromol/l, 7.01 +/- 0.01) (P < 0.05) consistent with mitochondrial dysfunction. Oxygen supplementation did not change resting metabolites in either MM or the control group (P > 0.05). Inferred maximal ATP synthesis rate improved by 33% with oxygen in MM (21 +/- 3 vs. 28 +/- 5 mmol/(l min), P < 0.05) but only improved by 5% in controls (40 +/- 3 vs. 42 +/- 3 mmol/(l min), P > 0.05). We conclude that oxygen therapy is associated with significant improvements in muscle metabolism in patients with MM. These data suggest that patients with MM could benefit from therapies which improve the provision of oxygen.

Adenosine Diphosphate↗

PubMed2005

Aging muscle.

Age causes structural and functional changes in skeletal muscle in a wide range of species, including humans. Muscle changes in humans start in the fourth decade of life and cause frailty and disabilities. Associated changes in body composition form the basis of many metabolic disorders, such as insulin resistance, type 2 diabetes, hypertension, and hyperlipidemia, which result in an increased incidence of cardiovascular death. Decreases in the synthesis rates of many muscle proteins, specifically of myosin heavy chain and mitochondrial proteins, occur with age. The underlying causes of the reduction in mitochondrial biogenesis and ATP production seem to be decreases in mitochondrial DNA and messenger RNA. Reduced ATP production could be the basis of reduced muscle protein turnover, which requires energy. Both aerobic exercise and resistance exercise enhance muscle protein synthesis and mitochondrial biogenesis. Insulin and amino acids have also been shown to enhance muscle mitochondrial biogenesis and mitochondrial protein synthesis. However, the insulin-induced increase in muscle mitochondrial ATP production is defective in type 2 diabetic patients with insulin resistance. Moreover, a dissociation between increases in muscle mitochondrial biogenesis and insulin sensitivity after exercise has been noted in older persons. It remains to be determined whether muscle mitochondrial dysfunction causes or results from insulin resistance. Exercise seems to enhance the efficiency of muscle mitochondrial DNA in rodents. Reduced physical activity as a contributor of age-related mitochondrial dysfunction remains to be determined. It is proposed that a reduction in tissue mitochondrial ATP production signals the hypothalamic centers to reduce spontaneous physical activities. Voluntary physical activity is regulated by cognitive centers and could attenuate the progressive decline in mitochondrial functions that occurs with age.

Adult↗

PubMed2006

Repeated static contractions increase mitochondrial vulnerability toward oxidative stress in human skeletal muscle.

Repeated static contractions (RSC) induce large fluctuations in tissue oxygen tension and increase the generation of reactive oxygen species (ROS). This study investigated the effect of RSC on muscle contractility, mitochondrial respiratory function, and in vitro sarcoplasmic reticulum (SR) Ca(2+) kinetics in human muscle. Ten male subjects performed five bouts of static knee extension with 10-min rest in between. Each bout of RSC (target torque 66% of maximal voluntary contraction torque) was maintained to fatigue. Muscle biopsies were taken preexercise and 0.3 and 24 h postexercise from vastus lateralis. Mitochondria were isolated and respiratory function measured after incubation with H(2)O(2) (HPX) or control medium (Con). Mitochondrial function was not affected by RSC during Con. However, RSC exacerbated mitochondrial dysfunction during HPX, resulting in decreased respiratory control index, decreased mitochondrial efficiency (phosphorylated ADP-to-oxygen consumed ratio), and increased noncoupled respiration (HPX/Con post- vs. preexercise). SR Ca(2+) uptake rate was lower 0.3 vs. 24 h postexercise, whereas SR Ca(2+) release rate was unchanged. RSC resulted in long-lasting changes in muscle contractility, including reduced maximal torque, low-frequency fatigue, and faster torque relaxation. It is concluded that RSC increases mitochondrial vulnerability toward ROS, reduces SR Ca(2+) uptake rate, and causes low-frequency fatigue. Although conclusive evidence is lacking, we suggest that these changes are related to increased formation of ROS during RSC.

Adult↗

PubMed2003

Focal levator ani eventrations: detection and characterization by magnetic resonance in patients with pelvic floor dysfunction.

The aim of this study was to assess the frequency and imaging characteristics of focal levator eventrations in patients with pelvic floor dysfunction on magnetic resonance (MRI). A review of 81 dynamic MR pelvic examinations in patients with pelvic floor dysfunction was carried out to detect and characterize focal eventrations in the levator ani muscle. These were defined as muscle outpouchings which made an angle of >180 degrees with the remainder of the muscle and had a depth of >or=1 cm. Of 81 patients 11(13.5%) had focal eventrations in the levator muscle on MRI: bilateral in 2 cases, right in 5 and left in 4. There was protrusion of pelvic viscera into the eventration in 5 cases, fat in 7 and fluid in 1. Focal levator ani muscle abnormalities are not uncommon on MRI in patients with pelvic floor dysfunction. Characterization of levator muscle morphology can be useful as a research tool in this population.

Adult↗