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Dynamic muscle strength training in stroke patients: effects on knee extension torque, electromyographic activity, and motor function.

The effects of training with isokinetic maximal voluntary knee extensions were studied in stroke patients. Two groups of 10 patients each trained twice a week for 6 weeks. One group trained exclusively eccentric movements and the other exclusively concentric movements. The effects were evaluated from the following tests before and after the training period. The maximal voluntary strength in concentric and eccentric actions of the knee extensor and flexor muscles was recorded together with surface electromyography at constant velocities of 60, 120, and 180 deg.s-1 on three different days. The body weight distribution on the legs while rising and sitting down was measured with two force plates. The self-selected and maximal walking speeds and the swing to stride ratio of the paretic leg were measured. After the training period, the knee extensor strength had increased in eccentric and concentric actions in both groups (p < .05). The eccentric and the concentric strength in the paretic leg relative to that of the nonparetic leg increased in the eccentrically trained group (p < .05) but not in the concentrically trained group. The restraint of the antagonistic muscles in concentric movements increased after concentric (p < .05) but not eccentric training. A nearly symmetrical body weight distribution on the legs in rising from a sitting position was noted after eccentric (p < .05) but not concentric training. Changes in walking variables were not significantly different between the groups. Eccentric knee extensor training was thus found to have some advantages as compared to concentric training in stroke patients.

Aged↗

A novel water-soluble selective CRF1 receptor antagonist, NBI 35965, blunts stress-induced visceral hyperalgesia and colonic motor function in rats.

The stress response involves the activation of two corticotropin-releasing factor (CRF) receptor subtypes. We investigated the role of CRF1 in stress-related visceral responses. A novel water-soluble tricyclic CRF1 antagonist, NBI 35965 was developed that displayed a high affinity for CRF1 (Ki approximately 4 nM) while having no binding affinity to CRF2. This antagonist also inhibited the stimulation of cAMP induced by sauvagine in CRF1 transfected cells. NBI 35965 administered per orally (p.o.) in rats (1, 3, 10 or 30 mg/kg) inhibited dose-dependently [125I]sauvagine binding selectively at brain sites of CRF1 distribution as shown by ex vivo receptor autoradiography. At the highest doses, NBI 35965 completely prevented [125I]sauvagine labeling in the cortex. NBI 35965 (10 mg/kg) administered p.o. or subcutaneously (s.c.) 1 h before intravenous CRF completely blocked the 81% shortening of distal colonic transit time induced by CRF. NBI 35965 (20 mg/kg s.c.) significantly reduced the defecation in response to water avoidance stress but not that induced by s.c. carbachol. In adult male Long-Evans rats that had undergone maternal separation, acute water avoidance stress significantly increased the visceromotor response to colorectal distention (20-80 mmHg) by 42+/-19% compared with the response before stress. Stress-induced visceral hyperalgesia was abolished by NBI 35965 (20 mg/kg, s.c.). The data show that NBI 35965 is a novel water-soluble selective CRF1 antagonist with bioavailability to the brain upon peripheral administration and that CRF1 receptor signaling pathways are involved in water avoidance stress-induced hyperalgesia to colorectal distention and stimulation of colonic transit.

Amphibian Proteins↗

Role of cholecystokinin in regulation of gastrointestinal motor functions.

By means of loxiglumide, a potent and highly specific antagonist for cholecystokinin (CCK), the effects of blocking CCK receptors on gastrointestinal motility were investigated in a placebo-controlled study in healthy young men (aged 21-39, mean 24 years). Gallbladder contraction stimulated by ingestion of a liquid test meal was completely abolished by oral administration of loxiglumide 30 min before the test meal. Gastric emptying of radio-opaque markers ingested with the test meal was significantly accelerated by loxiglumide (area under the curve [markers x h] 33.3 [SEM 3.8] vs 17.9 [2.7] after placebo). No effect of loxiglumide was found on small-bowel transit time, but 7 days' treatment with oral loxiglumide (800 mg three times daily) significantly shortened colonic transit time (29.4 [4.1] h after placebo, 15.0 [3.4] h after loxiglumide). It is concluded that CCK is an important mediator of meal-induced gallbladder contraction and is involved in the regulation of gastrointestinal motility in man.

4-Aminobenzoic Acid↗

Striatal implantation of GDNF releasing biodegradable microspheres promotes recovery of motor function in a partial model of Parkinson's disease.

The recent identification of neurotrophic factors, such as the glial cell line derived neurotrophic factor (GDNF), acting on mesencephalic dopaminergic neurons, offers the possibility to stimulate the axonal regeneration of these cells which are affected in Parkinson's disease. Nevertheless, a safe and efficient GDNF delivery system that may be used in clinical trials is still lacking. We have developed GDNF-releasing microspheres capable of releasing the neurotrophic factor for at least 2 months in vivo. In this study we demonstrate that these microspheres, when implanted in the brains of 'Parkinsonian' rats, were well tolerated, and were able to induce sprouting of the preserved dopaminergic fibers with synaptogenesis. Moreover, this neural regeneration was accompanied by functional improvement. The implantation of GDNF-releasing microspheres could be a promising strategy in the treatment of Parkinson's disease.

Absorbable Implants↗

Urinary incontinence in the elderly: relation to cognitive and motor function.

Urinary incontinence is a common problem in older subjects, very often wrongfully accepted as a normal part of the aging process. A total of 520 subjects (208 males and 312 females; mean age 74.8 +/- 11.8 years), from both private- and nursing-home dwelling populations, were included in this study aimed to estimate the incidence of urinary incontinence and identify factors associated with condition, in aged subjects. The incidence and type of urinary incontinence (stress, urge or mixed incontinence) were assessed by structured questionnaires and diagnosis was confirmed by a seven-day consecutive voiding diary. Assessment of physical, cognitive and emotional functions was performed on each subject using the Mini Mental State Examination (MMSE), Instrumental Activities of Daily Living Scale (IADL), Tinetti Scale (gait), Tinetti Scale (balance) and Geriatric Depression Scale (GDS) instruments. In the total population sample the incidence of urinary incontinence was 47.9%. The incontinence cases were classified, according to the different types, as: stress incontinence (males: 3.4%; females: 8.7%; males+females: 6.5%); urge incontinence (males: 27.4%; females: 31.4%; males+females: 29.8%); mixed incontinence (males: 20.2%; females: 5.8%; males+females: 11.5%). In the total population sample, no significant relationship was found between age and prevalence of urinary incontinence. In the elderly female group, age significantly correlated in a direct manner with urge incontinence (P<0.01) and inversely with stress incontinence (P<0.001). Only in the male sex group age significantly correlated with mixed incontinence (P<0.005). Multiple linear regression analysis showed that the dependent variable 'incontinence' could be predicted by MMSE (P<0.001) in the male sex group and by the Tinetti Scale (gait) (P<0.001) in the female sex group.

Journal Article↗

Picolinic acid and indole-2-carboxylic acid: two types of glycinergic compounds modulate motor function differentially.

1. A putative agonist for the strychnine-sensitive glycine receptor picolinic acid was tested for its anticonvulsant activities in mice and muscle-relaxant activities in rats and compared with indole-2-carboxylic acid (I2CA), an antagonist for the strychnine-insensitive glycine receptor. Their effects on segmental reflexes in the cat spinal cord were examined to elucidate their sites of action. 2. Picolinic acid (200 and 400 mg/kg IP) delayed the onsets of strychnine- but not pentylenetetrazole-induced seizures. It delayed the onsets of bicuculline-induced seizures only at the higher dose. I2CA (200 and 400 mg/kg IP) delayed the onsets of these 3 kinds of seizures. Both compounds reduced muscle tone in rat decerebrate rigidity at a dose of 100 mg/kg IV. 3. Picolinate methylester, a picolinate derivative with higher lipophilicity, depressed spinal reflexes in both intact and spinalized cats at cumulative doses of 25 to 200 mg/kg IV. I2CA (50 mg/kg IV) inhibited spinal reflexes only in intact preparations. 4. These results suggest that the anticonvulsant and muscle-relaxant activities of picolinic acid (PA) are due to inhibition of spinal neurons, but that I2CA selectively affects supraspinal structures.

Animals↗

Testing motor functions of the frontal zone in the locomotion of Amoeba proteus.

The hypothesis which attributes the motive power to the frontal zone has been tested by cinematographic analysis of the movements of amoeba, in which the front was either blocked by negative stimuli or destroyed. Partial inhibition and consecutive reorganization of the frontal activity by a beam of light had minor effect on the retraction of other body parts. Microsurgical destruction of the whole frontal zone had no effect on the functions of more posteriorly situated cell regions, which continue to contract and squeeze the endoplasm out into the external medium.

Amoeba↗

A survey of trinucleotide/tandem repeat-containing transcripts (TNRTs) isolated from human spinal cord to identify genes containing unstable DNA regions as candidates for disorders of motor function.

Expansion of unstable DNA regions containing trinucleotide/tandem repeats (TNRs) represents a common genetic mutation in hereditary forms of neurological disorders. The spectrum of neurological diseases linked to TNR expansions has recently broadened to include conditions with both dominant and recessive inheritance and those with or without clinical anticipation. In view of the frequent involvement of the spinal cord in neurodegenerative disorders, we have analysed this key tissue to identify pathological TNRs. We have used two approaches to isolate a wide range of trinucleotide/tandem repeat-containing transcripts (TNRTs) from human spinal cord, firstly a polymerase chain reaction (PCR)-based method and secondly by screening a spinal cord cDNA library immobilised on a membrane. Overall, 97 TNRTs belonging to a number of key protein families, the most highly represented being transcription factors, intracellular signalling molecules and cytoskeletal proteins, have been isolated most of which have not previously been considered as potential disease-causing genes. The commonest repeat motifs found in our study were CAG (37%) and CCG (24%). Known genes involved in DNA repeat expansion-related neurological disorders (e.g., AAD10, Ataxin-3, Huntingtin) were detected which validated our methods. We have characterised homogeneous TNRs among the detected gene candidates in a search for potential pathological repeat expansions. The potential role of the gene candidates identified is discussed in terms of their contribution to neurodegenerative processes.

Gene Library↗

Effects of experimental muscle pain on muscle activity and co-ordination during static and dynamic motor function.

The relation between muscle pain, muscle activity, and muscle co-ordination is still controversial. The present human study investigates the influence of experimental muscle pain on resting, static, and dynamic muscle activity. In the resting and static experiments, the electromyography (EMG) activity and the contraction force of m. tibialis anterior were assessed before and after injection of 0.5 ml hypertonic saline (5%) into the same muscle. In the dynamic experiment, injections of 0.5 ml hypertonic saline (5%) were performed into either m. tibialis anterior (TA) or m. gastrocnemius (GA) and the muscle activity and co-ordination were investigated during gait on a treadmill by EMG recordings from m. TA and m. GA. At rest no evidence of EMG hyperactivity was found during muscle pain. The maximal voluntary contraction (MVC) during muscle pain was significantly lower than the control condition (P < 0.05). During a static contraction at 80% of the pre-pain MVC muscle pain caused a significant reduction in endurance time (P < 0.043). During dynamic contractions, muscle pain resulted in a significant decrease of the EMG activity in the muscle, agonistic to the painful muscle (P < 0.05), and a significant increase of the EMG activity of the muscle, antagonistic to the painful muscle (P < 0.05). Muscle pain seems to cause a general protection of painful muscles during both static and dynamic contractions. The increased EMG activity of the muscle antagonistic to the painful muscle is probably a functional adaptation of muscle co-ordination in order to limit movements. Modulation of muscle activity by muscle pain could be controlled via inhibition of muscles agonistic to the movement and/or excitation of muscles antagonistic to the movement. The present results are in accordance with the pain-adaptation model (Lund, J.P., Stohler, C.S. and Widmer, C.G. In: H. Vaerøy and H. Merskey (Eds.), Progress in Fibromyalgia and Myofascial Pain. Elsevier, Amsterdam, 1993, pp. 311-327.) which predicts increased activity of antagonistic muscle and decreased activity of agonistic muscle during experimental and clinical muscle pain.

Adult↗

Three-dimensional structure of functional motor proteins on microtubules.

BACKGROUND: Kinesins are a superfamily of motor proteins that use ATP hydrolysis to fuel movement along microtubules and participate in many crucial phases of the eukaryotic cell cycle. Usually these motors are heterotetramers of two heavy and two light chains, and have globular motor domains on the two heavy chains. Most kinesins move towards the microtubule 'plus end', but some, such as ncd (nonclaret disjunctional protein), move in the opposite direction. Heavy chain dimers produced by overexpression are viable motors. RESULTS: In order to establish whether the opposite directionality of kinesin and ncd dimers is related to notable conformational differences, we have used electron cryo-microscopy and three-dimensional reconstruction methods to investigate the structure of kinesin and ncd dimers attached to microtubules in the presence of AMP-PNP (5'-adenylylimidodiphosphate), a nonhydrolyzable ATP analogue. Three-dimensional maps of the motor-microtubule complexes show the motors to have one unattached, and one attached head per tubulin dimer. The polarity of the reconstructions was determined for each individual microtubule. Attachment occurs on the crest of a protofilament at the end of the tubulin dimer that points towards the plus end of the microtubule. The attached head extends over the next tubulin molecule along the protofilament. The unattached heads of kinesin and ncd have distinctly different conformations. CONCLUSIONS: The attached heads of kinesin and ncd appear to be similar and to interact with the same region of the plus end-oriented tubulin subunits. The free heads, however, are quite different, which suggests that directionality could be determined by differences in the dimer conformations. Work is in progress to obtain three-dimensional maps in the presence of different nucleotides with the aim of understanding how these motors move along microtubules.

Animals↗