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Muscular Activity (muscular + activity)
Selected AbstractsStudies on dentin grafts to bone defects in rabbit tibia and mandible; development of an experimental modelDENTAL TRAUMATOLOGY, Issue 1 2009Lars Andersson This property may possibly be used as an alternative or supplement to bone grafting to defective areas after trauma prior to treatment with osseointegrated implants. Hence, the objective of this study was to investigate if dentin can be used as a graft in bone defects in an experimental rabbit model. Materials and Methods:, Eight New Zealand White Rabbits were used to prepare bone cavities either in the angle of the mandible or tibia. Six of the eight tibial and six of the eight mandibular bone defects were filled with dentin blocks from human premolars which were extracted for orthodontic treatment. Two mandibular and two tibial bone cavities were used as controls and all the rabbits were sacrificed after 3 months. Radiographic and histological examinations were performed. Results:, There was a difference in healing pattern between the mandibular and tibial defects. In the mandible, the dentin blocks were resorbed to a larger extent and more often surrounded by fibrous tissue, probably due to the fact that the dentin blocks were mobile because of the thin mandibles and muscular activity in that area. Only some dentin blocks were ankylosed with the mandibular bone. In the tibia however, all dentin blocks were fused to bone over a large area. Osseous replacement resorption was seen. In control cavities, bone formation was seen but was never complete. No signs of inflammatory changes were seen in any fused grafts. Conclusions:, Dentin grafts have a potential to be incorporated in bone without inflammation and can be used as bone inducer and later replaced by bone. Thus, rabbit tibia served as a better model for further studies of this phenomenon when compared to the mandible. [source] Reactive oxygen species are signalling molecules for skeletal muscle adaptationEXPERIMENTAL PHYSIOLOGY, Issue 1 2010Scott K. Powers Increased reactive oxygen species (ROS) production is crucial to the remodelling that occurs in skeletal muscle in response to both exercise training and prolonged periods of disuse. This review discusses the redox-sensitive signalling pathways that are responsible for this ROS-induced skeletal muscle adaptation. We begin with a discussion of the sites of ROS production in skeletal muscle fibres. This is followed by an overview of the putative redox-sensitive signalling pathways that promote skeletal muscle adaptation. Specifically, this discussion highlights redox-sensitive kinases, phosphatases and the transcription factor nuclear factor-,B. We also discuss the evidence that connects redox signalling to skeletal muscle adaptation in response to increased muscular activity (i.e. exercise training) and during prolonged periods of muscular inactivity (i.e. immobilization). In an effort to stimulate further research, we conclude with a discussion of unanswered questions about redox signalling in skeletal muscle. [source] Evaluating the physiological and physical consequences of capture on post-release survivorship in large pelagic fishesFISHERIES MANAGEMENT & ECOLOGY, Issue 2 2007G. B. SKOMAL Abstract, Sharks, tunas and billfishes are fished extensively throughout the world. Domestic and international management measures (quotas, minimum sizes, bag limits) mandate release of a large, yet poorly quantified, number of these fishes annually. Post-release survivorship is difficult to evaluate, because standard methods are not applicable to large oceanic fishes. This paper presents information on the current approaches to characterising capture stress and survivorship in sharks, tunas and marlins. To assess mortality associated with capture stress, researchers must examine the cumulative impacts of physical trauma and physiological stress. Physical trauma, manifested as external and internal tissue and organ damage, is caused by fishing gear and handling. Gross examination and histopathological sampling have been used to assess physical trauma and to infer post-release survivorship. Exhaustive anaerobic muscular activity and time out of water cause physiological stress, which has been quantified in these fishes through the analyses of blood chemistry. Conventional, acoustic and archival tagging have been used to assess post-release survivorship in these species. Future studies relating capture stress and post-release survivorship could yield information that helps fishermen increase survivorship when practicing catch and release. [source] Objective emotional assessment of tactile hair properties and their modulation by different product worldsINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 3 2002W. Boucsein Synopsis Tactile properties of cosmetic products constitute weak stimuli and thus can be expected to be easily modified by mental images. In order to enhance an intended positive-emotion-inducing effect of such a product, its experience can be embedded in a certain ,world' that generates a positive emotional imagination. The present study investigated such an influence in 12 males and 12 females, half of each being laymen and experts in sensory assessment. Two product worlds (emotional and technical) and three different hair samples, two of them treated with different shampoos and an untreated one as control, were presented to each subject in counter-balanced order of all six combinations. An objective emotional assessment using a psychophysiological technique developed in an earlier study was applied and compared with a traditional sensory assessment. Among the physiological measures, peripheral blood volume and facial muscular activity were the most sensitive in revealing effects of and interactions between the product worlds and hair samples. A multivariate evaluation of the physiological data revealed three discriminant functions that explained 78.4% of the total variance and enabled a re-classification considerably better than chance. The first discriminant function clearly separated the treated from the untreated hair samples which was not possible by subjective ratings or traditional sensory assessment. The two other discriminant functions comprised a hedonistic and a product world factor. The emotional product world exerted the largest influence in case of the weakest tactile differences between the hair samples, and its influence was larger on laymen than on experts. Gender effects were most prominent in the subjective domain. In conclusion, multivariate psychophysiological methodology is superior to traditional sensory assessment in revealing subtle differences in the tactile perception of cosmetic products. Résumé Les propriétés tactiles des produits cosmétiques constituent de faibles stimuli, de sorte que l'on peut s'attendre à ce qu'elles soient facilement modifiées par des images mentales. Afin d'intensifier l'effet intentionnellement incitant à une émotion positive envers un tel produit, son expérience peut être introduite dans un certain ,environnement' qui engendrerait une imagination émotionelle positive. La présente étude a testé telle influence sur 12 hommes et 12 femmes, la moitié de chaque groupe étant noninitiée et l'autre experte en évaluation sensorielle. Nous avons présentéà chaque sujet, par ordre contrebalancé des six possibilités, deux ,environnements' du produit (émotif et technique), et trois différents échantillons capillaires dont deux où les cheveux étaient traités par différents shampooings, et, pour le contrôle, un échantillon de cheveux nontraités. Nous avons employé une évaluation émotionelle objective par une technique psychophysiologique développée durant une étude précédente et l'avons comparée à une évaluation sensorielle traditionnelle. Parmi les mesures physiologiques, le volume sanguin périphérique et les activités des muscles faciaux étaient exceptionnellement sensibles à manifester les effets des ,environnements' du produit, et des échantillons, ainsi que les interactions entre eux. Une évaluation multivariante des données physiologiques dévoila trois fonctions discriminantes expliquant les 78.4% de l'ensemble de la variance, et permettant une re-classification considérablement meilleure que le hasard. La première fonction discriminante a nettement distingué les échantillons de cheveux traités de ceux nontraités; ce qui n'était pas possible à travers une évaluation subjective ou des mesures sensorielles traditionnelles. Les deux autres fonctions discriminantes comportaient un facteur hédoniste et d'environnement du produit. Dans le cas des plus faibles différences tactiles entre les échantillons capillaires, l'environnement émotif du produit a exercé plus d'influence sur les noninitiés que sur les experts. Les effets du genre humain étaient surtout marquants dans le domaine subjectif. En conclusion, pour dévoiler les subtiles différences dans la perception tactile des produits cosmétiques, la méthodologie psychophysiologique multivariante est supérieure à l'évaluation sensorielle traditionnelle. [source] Relation between clenching strength and occlusal force distribution in primary dentitionJOURNAL OF ORAL REHABILITATION, Issue 3 2003H. Karibe summary, The aim of this study was to investigate the relation between clenching strength and occlusal force distribution in primary dentition. Twenty healthy children with normal occlusions: 11 boys and 9 girls, ages 3·2,5·8 years (avg. 4·5 years) were selected. Setting the bilateral masseter muscular activity at maximum clenching in full intercuspation as 100%, the occluding forces at 20, 40, 60, 80 and 100% clenching were recorded with pressure-sensitive sheets (Dental Prescale 50H, type R, Fuji Photo Film Co.), and the force of each primary tooth was analysed by computer (Occluzer FPD703). Occlusal force distribution was expressed as a percentage of the total occlusal force of each tooth and was compared between each clenching. There were no significant differences between various clenching strengths in the occlusal force distribution in primary dentition [one-way repeated-measures analysis of variance (anova)]. Thus, the results of the present study suggest that the distribution of occluding forces on a primary dental arch had its own pattern and that the clenching strength had no effect on that pattern. These patterns may be useful in determining occlusal function in children. [source] Immediate effect of a stabilization splint on masticatory muscle activity in temporomandibular disorder patientsJOURNAL OF ORAL REHABILITATION, Issue 9 2002V. F. FERRARIO Summary Surface electromyography (EMG) allows the quantification of the occlusal equilibrium in dysfunctional patients, for instance in those with temporomandibular disorders (TMD). Fourteen patients (ten women, four men) with internal derangement type I were selected among the TMD patients referred to a private practice in Milan. A stabilization splint with posterior contacts was made for each patient. To verify the static neuromuscular equilibrium of occlusion, EMG activity of left and right temporal and masseter muscles was recorded in all patients and the activity (ratio between the activities of the temporal and masseter muscles) index was computed over a maximum voluntary clench test of 3 s. Muscular waveforms were also analysed by computing a percentage overlapping coefficient (POC, an index of the symmetric distribution of the muscular activity determined by the occlusion). The total electrical activity was measured by calculating the area under the entire muscular waveforms. In all patients EMG was performed just before and immediately after the insertion of the splint and data were compared by paired Student's t -tests. Overall, the splint reduced the electrical activity of the analysed muscles (P < 0·005) and made it more equilibrated both between the left and right side (larger symmetry in the masseter muscle POC, P < 0·05) and between the temporal and masseter muscles (activity index, P < 0·01). [source] Tibio-femoral loading during human gait and stair climbingJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2004William R. Taylor Abstract Surgical intervention of the knee joint routinely endeavors to recreate a physiologically normal joint loading environment. The loading conditions resulting from osteotomies, fracture treatment, ligament replacements, and arthroplasties of the knee are considered to have an impact on the long term clinical outcome; however, knowledge regarding in vivo loading conditions is limited. Using a previously validated musculoskeletal lower limb model, we predicted the tibio-femoral joint contact forces that occur in the human knee during the common daily activities of walking and stair climbing. The average resultant peak force during walking was 3.1 times body weight (BW) across four total hip arthroplasty patients. Inter-individual variations proved larger than the variation of forces for each patient repeating the same task. Forces through the knee were considerably larger during stair climbing than during walking: the average resultant peak force during stair climbing was 5.4 BW although peaks of up to 6.2 BW were calculated for one particular patient. Average anteroposterior peak shear components of 0.6 BW were determined during walking and 1.3 BW during stair climbing. These results confirm both the joint contact forces reported in the literature and the importance of muscular activity in creating high forces across the joint. The magnitudes of these forces, specifically in shear, have implications for all forms of surgical intervention in the knee. The data demonstrate that high contact and shear forces are generated during weight bearing combined with knee flexion angles greater than approximately 15°. Clinically, the conditions that produce these larger contact forces should be avoided during post-operative rehabilitation. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] Influence of muscular activity on local mineralization patterns in metatarsals of the embryonic mouseJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2000E. Tanck This study addressed the theory that local mechanical loading may influence the development of embryonic long bones. Embryonic mouse metatarsal rudiments were cultured as whole organs, and the geometry of the primary ossification center was compared with that of rudiments that had developed in utero. The mineralization front in vivo was found to be nearly straight, whereas in vitro it acquired a more convex shape due to a slower mineralization rate at the periphery of the mineralized cylinder. A poroelastic finite element analysis was performed to calculate the local distributions of distortional strain and fluid pressure at the mineralization front in the metatarsal during loading in vivo as a result of muscle contractions in the embryonic hindlimbs. The distribution of fluid pressure from the finite element analysis could not explain the difference in mineralization shape. The most likely candidate for the difference was the distortional strain, resulting from muscle contraction, which is absent in vitro, because its value at the periphery was significantly higher than in the center of the tissue. Without external loads, the mineralization process may be considered as pre-programmed, starting at the center of the tissue and resulting in a spherical mineralization front. Strain modulates the rate of the mineralization process in vivo, resulting in the straight mineralization front. These results confirm that disturbances in muscle development are likely to produce disturbed mineralization patterns, resulting in a disordered osteogenic process. [source] Feasibility of electromyography (sEMG) in measuring muscular activity during spinal anaesthesia in patients undergoing knee arthroplastyACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 4 2005L. Niemi-Murola Background:, Bromage scale (0,3) is used to measure the degree of motor block during spinal anaesthesia. However, an estimation of motor block is difficult during surgery. The purpose of this study was to evaluate the feasibility of surface EMG describing spontaneous muscular activity in the lower extremities during spinal anaesthesia. Methods:, In part I of the study, 13 patients undergoing day case surgery were studied. They received 10 mg hyperbaric bupivacaine at interspace L3,4. EMG, sensory and muscular block were measured at 5-min intervals during the first 30 min and then every 15 min until the patient was able to flex the knee. In part II of the study, 16 patients undergoing knee arthroplasty received 10 mg bupivacaine through spinal catheter at interspace L3,4 (Group CSA). An additional bolus of 2.5 mg was administered using EMG-guidance, if needed. Another group, 15 patients, received a single bolus of bupivacaine (15,20 mg) at L3,4 (Group Bolus). EMG, muscular and sensory block were monitored as described above. The epidural catheter was used as rescue. Results:, Part I: EMG compared to modified Bromage scale showed a significant correlation (P < 0.01, Spearman rank correlation). Part II: The amount of bupivacaine was significantly reduced with EMG guidance when compared with the single bolus group (14.0 mg vs. 17.0 mg) (P < 0.05 Mann,Whitney U). Motor block started to recover before the sensory block in 7/15 CSA patients vs. 1/15 Bolus patient. Conclusion:, Stable maximal sensory block does not necessarily correlate with adequate motor block in patients receiving spinal anaesthesia induced with small bolus doses. In spite of electrical noise, EMG-guided administration of spinal anaesthesia significantly reduced the amount of bupivacaine compared to the hospital routine. Further studies are needed to develop the method. [source] Force impairment in calpain 3,deficient mice is not correlated with mechanical disruptionMUSCLE AND NERVE, Issue 5 2003Françoise Fougerousse MD Abstract Defects in human calpain 3 are responsible for limb-girdle muscular dystrophy type 2A, an autosomal-recessive disorder characterized mainly by late-onset proximal muscular atrophy. A corresponding murine model has previously been generated by gene targeting. In this report, muscular activity of calpain 3,deficient (capn3,/,) mice was evaluated at different ages. Growth curves showed a progressive global muscular atrophy. Histological examination throughout the lifespan of mice confirmed the dystrophic lesions. Whole animal tests showed only a mild significant impairment of the forelimbs. Studies of the mechanical properties of selected isolated fast- and slow-twitch muscles demonstrated that slow-twitch muscles were significantly weaker in capn3,/, mice than in wild-type mice. Three different tests showed that there was no membrane disruption, suggesting a nonmechanical etiology of capn3,/, mice dystrophy. These findings are consistent with a mechanism involving signaling systems. Muscle Nerve 27: 616,623, 2003 [source] Muscle toxicity with statins,PHARMACOEPIDEMIOLOGY AND DRUG SAFETY, Issue 3 2010Karin Hedenmalm MD Abstract Purpose Statins rarely cause serious muscle toxicity and rhabdomyolysis. The aim of our investigation was to identify and quantify potential risk factors for statin-induced rhabdomyolysis. Methods All cases of suspected adverse reactions to statins reported to the Swedish Adverse Drug Reactions Advisory Committee until 15 September 2006 containing the codes myalgia, myopathy, increased serum creatine kinase (CK), myoglobinuria or rhabdomyolysis were included in the study. Cases were classified into different CK categories, where cases with CK levels >10 times the upper limit of normal (ULN) laboratory range were compared with cases with normal CK levels (in some analyses cases with CK not measured were also included as controls). Fisher's test and multiple logistic regression were used to test the degree of association. Results A total of 338 cases with muscle toxicity were identified. CK had not been measured in 148 cases. Of the remaining 190 cases, 59 were classified as rhabdomyolysis, 62 had CK increases below the level of rhabdomyolysis, 69 had normal CK and 2 contained insufficient information to classify the degree of CK increase. A high statin dose and concomitant interacting drug treatment were over-represented among cases with rhabdomyolysis compared with cases with normal CK. Renal disease and unusual strenuous muscular activity were also associated with an increased risk of rhabdomyolysis when the control group included cases with CK not measured. Conclusion Results from our study support previous studies indicating that the risk of rhabdomyolysis with statin treatment increases with increase in systemic exposure to the statin. Renal disease and unusual strenuous muscular activity may also contribute to an increased risk of rhabdomyolysis. Copyright © 2009 John Wiley & Sons, Ltd. [source] Synthesis and mobilization of glycogen and trehalose in adult male Rhodnius prolixusARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 1 2009Ana C. Mariano Abstract The vector of Chagas' disease, Rhodnius prolixus, feeds exclusively on blood. The blood meals are slowly digested, and these insects wait some weeks before the next meal. During the life of an insect, energy-requiring processes such as moulting, adult gonadal and reproductive growth, vitellogenesis, muscular activity, and fasting, lead to increased metabolism. Carbohydrates are a major source of energy and their mobilization is important. We determined the amounts of glycogen, trehalose, and glucose present in the fat body and/or hemolymph of adult males of R. prolixus and recorded the processes of accumulation and mobilization of these carbohydrates. We also tested our hypothesis that these processes are under endocrine control. The amount of glycogen in the fat body progressively increased until the fourth day after feeding (from 9.3±2.2 to 77. 3±7.5,µg/fat body), then declined to values around 36.3±4.9,µg/fat body on the fifteenth day after the blood meal. Glycogen synthesis was eliminated in decapitated insects and head-transplanted insects synthesized glycogen. The amount of trehalose in the fat body increased until the sixth day after feeding (from 16. 6±1.7 to 40. 6±5.3,nmol/fat body), decreased abruptly, and stabilized between days 7 and 15 at values ranging around 15,19,nmol/fat body. Decapitated insects did not synthesize trehalose after feeding, and this effect was reversed in head-transplanted insects. The concentration of trehalose in the hemolymph increased after the blood meal until the third day (from 0.07±0.01 to 0.75±0.05,mM) and at the fourth day it decreased until the ninth day (0.21±0.01,mM), when it increased again until the fourteenth day (0.79±0.06,mM) after the blood meal, and then declined again. In decapitated insects, trehalose concentrations did not increase soon after the blood meal and at the third day it was very low, but on the fourteenth day it was close to the control values. The concentration of glucose in the hemolymph of untreated insects remained low and constant (0.18±0.01,mM) during the 15 days after feeding, but in decapitated insects it progressively increased until the fifteenth day (2.00±0.10,mM). We recorded the highest trehalase activity in midgut, which was maximal at the eighth day after feeding (2,830±320,nmol of glucose/organ/h). We infer that in Rhodnius prolixus, the metabolism of glycogen, glucose, and trehalose are controlled by factors from the brain, according to physiological demands at different days after the blood meal. © 2009 Wiley Periodicals, Inc. [source] Cystic duct and Heister's "valves"CLINICAL ANATOMY, Issue 2 2005D. Dasgupta Abstract The anatomy and physiology of the cystic duct have been relatively neglected by anatomists and the function of the spiral mucosal folds or "valves" of Heister, first described in 1732, remains obscure. The gross and microscopic anatomy of the cystic duct is reviewed together with results from laboratory investigations into the function of the cystic duct and its spirally arranged folds. The duct and spiral folds contain muscle fibers responsive to pharmacologic, hormonal, and neural stimuli. There is, however, no convincing evidence of a discrete muscular sphincter within the duct. Although the cystic duct is unlikely to play a major role in gallbladder filling and emptying, it appears to function as more than a passive conduit. Coordinated, graded muscular activity in the cystic duct in response to hormonal and neural stimuli may facilitate gallbladder emptying. The principal function of the internal spiral folds that are found in man and other animals may be to preserve patency of this narrow, tortuous tube rather than to regulate bile flow. Clin. Anat. 18:81,87, 2005. © 2005 Wiley-Liss, Inc. [source] | |||||||||||||