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1
Evans, Carla A. « Anteroposterior skeletal change : Growth modification ». Seminars in Orthodontics 6, no 1 (mars 2000) : 21–32. http://dx.doi.org/10.1016/s1073-8746(00)80006-7.
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Shao, C. W., H. L. Chiu et S. K. Chang. « A Study on Generic Representation of Skeletal Remains Replication of Prehistoric Burial ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-5/W7 (13 août 2015) : 379–86. http://dx.doi.org/10.5194/isprsarchives-xl-5-w7-379-2015.
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Generic representation of skeletal remains from burials consists of three dimensions which include physical anthropologists, replication technicians, and promotional educators. For the reason that archaeological excavation is irreversible and disruptive, detail documentation and replication technologies are surely needed for many purposes. Unearthed bones during the process of 3D digital scanning need to go through reverse procedure, 3D scanning, digital model superimposition, rapid prototyping, mould making, and the integrated errors generated from the presentation of colours and textures are important issues for the presentation of replicate skeleton remains among professional decisions conducted by physical anthropologists, subjective determination of makers, and the expectations of viewers. This study presents several cases and examines current issues on display and replication technologies for human skeletal remains of prehistoric burials. <br><br> This study documented detail colour changes of human skeleton over time for the reference of reproduction. The tolerance errors of quantification and required technical qualification is acquired according to the precision of 3D scanning, the specification requirement of rapid prototyping machine, and the mould making process should following the professional requirement for physical anthropological study. Additionally, the colorimeter is adopted to record and analyse the “colour change” of the human skeletal remains from wet to dry condition. Then, the “colure change” is used to evaluate the “real” surface texture and colour presentation of human skeletal remains, and to limit the artistic presentation among the human skeletal remains reproduction. <br><br> The“Lingdao man No.1”, is a well preserved burial of early Neolithic period (8300 B.P.) excavated from Liangdao-Daowei site, Matsu, Taiwan , as the replicating object for this study. In this study, we examined the reproduction procedures step by step for ensuring the surface texture and colour of the replica matches the real human skeletal remains when discovered. The “colour change” of the skeleton documented and quantified in this study could be the reference for the future study and educational exhibition of human skeletal remain reproduction.
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Y, Popova, et Dinkova M. « THE TREATMENT EFFECTS OF THE COMBINED APPROACH : BRACESWITH PREFABRICATED MYOFUNCTIONALAPPLIANCE FOR GROWING CLASS II PATIENT ». International Journal of Advanced Research 8, no 12 (31 décembre 2020) : 421–30. http://dx.doi.org/10.21474/ijar01/12165.
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Objective:To evaluate the effect of combined treatment approach: braces with myofunctional appliance (trainer-T4B) on dentoalveolar, sagittal and vertical skeletal level in growing individuals with Skeletal and Dental Class II. Methods:Twenty teenagers with permanent dentition were treated with fixed appliance-braces in combination with myofunctional appliance (trainer-T4B). All patient completed thetreatment with occlusal Class I molar relationship. The patients made initial and final profile X-rays with cephalometric analysis. The evaluation of the treatment effects was made by comparing the initial and the final cephalometric analysis. Results:Significant sagittal skeletal changes were observed on all sagittal skeletal parameters, except for SNA°. A high positive association was found between the ANB angle change and Wits change. The changes in the rest of the vertical skeletal measurements were significant for two, including SN-M° and Go°. The dentoalveolar measurements showedsignificant changes in all parameters, except for i/M° where the change was marginally significant. Conclusion:The chosen treatment approachwaseffective for growing skeletal and dental Class II patients with permanent dentition.
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Yamakita, Yoshihiko, et Takayoshi Iio. « Conformational Change of Skeletal Muscle Troponin ». Journal of Biochemistry 105, no 6 (juin 1989) : 870–74. http://dx.doi.org/10.1093/oxfordjournals.jbchem.a122770.
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Wall, M., F. Ragazzola, L. C. Foster, A. Form et D. N. Schmidt. « Enhanced pH up-regulation enables the cold-water coral <i>Lophelia pertusa</i> ; to sustain growth in aragonite undersaturated conditions ». Biogeosciences Discussions 12, no 9 (5 mai 2015) : 6757–81. http://dx.doi.org/10.5194/bgd-12-6757-2015.
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Abstract. Cold-water corals are important habitat formers in deep-water ecosystems and at high latitudes. Ocean acidification and the resulting change in aragonite saturation are expected to affect these habitats and impact coral growth. Counter to expectations, the impact of saturation changes on the deep water coral Lophelia pertusa has been found to be less than expected, with the species sustaining growth even in undersaturated conditions. However, it is important to know whether such acclimation modifies the skeleton and thus its ecosystem functioning. Here we used Synchrotron X-Ray Tomography and Raman spectroscopy to examine changes in skeleton morphology and fibre orientation. We combined the morphological assessment with boron isotope analysis to determine if changes in growth are related to changes in control of calcification pH. Skeletal morphology is highly variable without clear changes in different saturation states. Raman investigations found no difference in macromorphological skeletal arrangement of early mineralization zones and secondary thickening between the treatments but revealed that the skeletal organic matrix layers were less distinct. The δ11B analyses show that L. pertusa up-regulates the internal calcifying fluid pH (pHcf) during calcification with disregard to ambient seawater pH and suggests that well-fed individuals can sustain a high internal pHcf. This indicates that any extra energetic demand required for calcification at low saturation is not detrimental to the skeletal morphology.
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Paskhover, Boris, David Durand, Emily Kamen et Neil A. Gordon. « Patterns of Change in Facial Skeletal Aging ». JAMA Facial Plastic Surgery 19, no 5 (septembre 2017) : 413–17. http://dx.doi.org/10.1001/jamafacial.2017.0743.
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Kang, Hee-Yong, Yoon-Kyu Kang et Jongbae Kim. « Improved Fall Detection Model on GRU Using PoseNet ». International Journal of Software Innovation 10, no 2 (avril 2022) : 1–11. http://dx.doi.org/10.4018/ijsi.289600.
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This paper investigate an improved detection method that estimates the acceleration of the head and shoulder key point position and position change using the skeleton key point information extracted using PoseNet from the image obtained from the low-cost 2D RGB camera, and improves the accuracy of fall judgment. This paper propose a fall detection method based on the post-fall characteristics of the post-fall, the speed of changes in the main point of the human body, and the change in the width and height ratio of the body's bounding box. The public data set was used to extract human skeletal features and train deep learning, GRU, and as a result of experiments, this paper find the following feature extraction methods. High classification accuracy can be achieved, and the proposed method showed a 99.8% fall detection success rate more effectively than the conventional method using raw skeletal data.
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Chung, Lee, Cho, Park, Baik, Lee et Kang. « Changes in Body Composition During Adjuvant FOLFOX Chemotherapy and Overall Survival in Non-Metastatic Colon Cancer ». Cancers 12, no 1 (24 décembre 2019) : 60. http://dx.doi.org/10.3390/cancers12010060.
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The impact of longitudinal anthropometric changes during adjuvant chemotherapy on long-term survival in non-metastatic colon cancer is unclear. Herein, we analyzed the prognostic significance of computed tomography (CT)-measured body composition changes in colon cancer patients who underwent surgery followed by adjuvant FOLFOX (folinic acid, 5-fluorouracil, oxaliplatin) chemotherapy. Data of 167 patients with stage III or high-risk stage II colon cancer were analyzed. Skeletal muscle index (SMI), skeletal muscle radiodensity (SMR), visceral fat index (VFI), subcutaneous fat index (SFI), and total fat index (TFI) changes during chemotherapy were calculated using preoperative and postchemotherapy CT image data. The Cox proportional hazard model was used to determine the correlation between changes in anthropometric values and overall survival (OS). The median changes (%) in SMI, SMR, VFI, SFI, and TFI over 210 days during chemotherapy were 8.7% (p < 0.001), 3.4% (p = 0.001), −19% (p < 0.001), −3.4% (p = 0.936), and −11.9% (p < 0.001), respectively. Cut-off values of changes in SMI (skeletal muscle index change, SMIC) and SMR (skeletal muscle radiodensity change, SMRC) were defined at −2% and −2 Hounsfield units (HU) respectively, whereas those of changes in VFI (visceral fat index change, VFIC), SFI (subcutaneous fat index change, SFIC), and TFI (total fat index change, TFIC) were based on values that provided the largest χ2 on the Mantel–Cox test. Multivariable analysis revealed that low SMR measured on a postchemotherapy CT scan (hazard ratio, HR: 0.32, 95% confidence interval, CI: 0.15–0.70, p = 0.004) and visceral fat loss of at least 46.57% (HR: 0.31, 95% CI: 0.14–0.69, p = 0.004) were independent poor prognostic factors for OS. Severe visceral fat loss during FOLFOX chemotherapy and low skeletal muscle radiodensity measured on postchemotherapy CT scans are associated with poor OS in stage III and high-risk stage II colon cancer patients.
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Moynihan, Molly A., Shahrouz Amini, Nathalie F. Goodkin, Jani T. I. Tanzil, J. Q. Isaiah Chua, Gareth N. Fabbro, Tung-Yung Fan, Daniela N. Schmidt et Ali Miserez. « Environmental impact on the mechanical properties of Porites spp. corals ». Coral Reefs 40, no 3 (8 mars 2021) : 701–17. http://dx.doi.org/10.1007/s00338-021-02064-3.
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AbstractDespite the economic and ecological importance of corals’ skeletal structure, as well as their predicted vulnerability to future climate change, few studies have examined the skeletal mechanical properties at the nanoscale. As climate change is predicted to alter coral growth and physiology, as well as increase mechanical stress events (e.g., bioerosion, storm frequency), it is crucial to understand how skeletal mechanical properties change with environmental conditions. Moreover, while material properties are intimately linked to the chemical composition of the skeleton, no previous study has examined mechanical properties alongside carbonate geochemical composition. Using Porites coral cores from a wide range of reef environments (Thailand, Singapore, Taiwan), we correlated coral’s micro-mechanical properties with chemical composition. In contrast to previous mechanical measurements of reef-building corals, we document unprecedented variability in the hardness, stiffness, and micro-cracking stress of Porites corals across reef environments, which may significantly decrease the structural integrity of reef substrate. Corals from environments with low salinity and high sedimentation had higher organic content and fractured at lower loads, suggesting that skeletal organic content caused enhanced embrittlement. Within individual coral cores, we observed seasonal variability in skeletal stiffness, and a relationship between high sea surface temperature, increased stiffness, and high-density. Regionally, lower Sr/Ca and higher Mg/Ca coincided with decreased stiffness and hardness, which is likely driven by increased amorphous calcium carbonate and skeletal organic content. If the coral is significantly embrittled, as measured here in samples from Singapore, faster erosion is expected. A decrease in skeletal stiffness will decrease the quality of reef substrate, enhance the rate of bioerosion by predators and borers, and increase colony dislodgement, resulting in widespread loss of structural complexity.
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Kim, Seyoung, et Sukyung Park. « The change of postural gain scaling by constrained somatosensory cues(1C3 Musculo-Skeletal Biomechanics III) ». Proceedings of the Asian Pacific Conference on Biomechanics : emerging science and technology in biomechanics 2007.3 (2007) : S55. http://dx.doi.org/10.1299/jsmeapbio.2007.3.s55.
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Yuyama, Ikuko, et Tomihiko Higuchi. « Differential gene expression in skeletal organic matrix proteins of scleractinian corals associated with mixed aragonite/calcite skeletons under low mMg/Ca conditions ». PeerJ 7 (15 juillet 2019) : e7241. http://dx.doi.org/10.7717/peerj.7241.
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Although coral skeletons generally comprise aragonite crystals, changes in the molar Mg/Ca ratio (mMg/Ca) in seawater result in the incorporation of calcite crystals. The formation mechanism of aragonite and calcite crystals in the scleractinian coral Acropora tenuis was therefore investigated by RNA-seq analysis, using early growth stage calcite (mMg/Ca = 0.5) and aragonite (mMg/Ca = 5.2)-based corals. As a result, 1,287 genes were up-regulated and 748 down-regulated in calcite-based corals. In particular, sixty-eight skeletogenesis-related genes, such as ectin, galaxin, and skeletal aspartic acid-rich protein, were detected as up-regulated, and six genes, such as uncharacterized skeletal organic matrix protein 5, down-regulated, in low-Mg/Ca conditions. Since the number of down-regulated genes associated with the skeletal organic matrix of aragonite skeletons was much lower than that of up-regulated genes, it is thought that corals actively initiate construction of an aragonite skeleton by the skeletal organic matrix in low-Mg/Ca conditions. In addition, different types of skeletal organic matrix proteins, extracellular matrix proteins and calcium ion binding proteins appeared to change their expression in both calcite-formed and normal corals, suggesting that the composition of these proteins could be a key factor in the selective formation of aragonite or calcite CaCO3.
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Brown, M., et E. M. Hasser. « Complexity of Age-Related Change in Skeletal Muscle ». Journals of Gerontology Series A : Biological Sciences and Medical Sciences 51A, no 2 (1 mars 1996) : B117—B123. http://dx.doi.org/10.1093/gerona/51a.2.b117.
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Eksriwong, Teerapat, et Udom Thongudomporn. « Alveolar bone response to maxillary incisor retraction using stable skeletal structures as a reference ». Angle Orthodontist 91, no 1 (9 septembre 2020) : 30–35. http://dx.doi.org/10.2319/022920-146.1.
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ABSTRACT Objectives To evaluate alveolar bone change in relation to root position change after maxillary incisor retraction via cone-beam computed tomography (CBCT) using stable skeletal structures as a reference. Materials and Methods A total of 17 subjects (age 24.7 ± 4.4 years) who required retraction of the maxillary incisors were included. Labial and palatal alveolar bone changes and root change were assessed from preretraction and 3 months postretraction CBCT images. The reference planes were based on stable skeletal structures. The Kruskal-Wallis test and Wilcoxon signed-rank test were used to compare changes within and between groups, as appropriate. Spearman rank correlations were used to identify the parameters that correlated with alveolar bone change. The significance level was set at .05. Results The labial alveolar bone change after maxillary incisor retraction was statistically significant (P < .05), and the bone remodeling/tooth movement (B/T) ratio was 1:1. However, the palatal bone remained unchanged (P > .05). The change in inclination was significantly related to labial alveolar bone change. Conclusions Using stable skeletal structures as a reference, the change in labial alveolar bone followed tooth movement in an almost 1:1 B/T ratio. Palatal alveolar bone did not remodel following maxillary incisor retraction. The change in inclination was associated with alveolar bone change.
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Yeh, Chang Tsang, Shu Cheng Lin, Hung Tai Lin, Hsuan Chun Tsai et Ho Cheng Cheng. « The Study of Skeletal Muscle Weight Change on Female Elder Adults ». Advanced Materials Research 680 (avril 2013) : 602–5. http://dx.doi.org/10.4028/www.scientific.net/amr.680.602.
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There are several problems after post-menopausal and higher age in the female. It may affect their physiological results, especially in the changes of their body composition. Older adults change their skeletal muscle weight when they are aging. But what differences their skeletal muscle weight change is still unknown. There is little previous research. Therefore, the purpose of this study was to investigate skeletal muscle weight change on female older adult. Methods: 48 women aged 41-80 years old were randomly selected and divided into four different age groups: 41-50 y (14 persons, abbreviated as number), 51-60 y (12), 61-70 y (12) and 71-80 y (10). All subjects’ body compositions were measured. Body composition analysis was conducted using the In Body 220 body composition analyzer. Data analysis was conducted using the SPSS statistical software for Windows 15.0. Independent one-way ANOVA was used as the statistical method at a significance level (α) of .05, followed by the Scheffé’s method to account for multiple comparisons. Results: Statistical analyses show that means of 4 skeletal muscle weight groups was 22.27±2.12(kg), 21.41±2.12(kg), 21.16±2.25(kg), 16.64±1.98(kg), there is significant differences in between 41-50y, 51-60y, 61-70y and 70-80 y group (Scheffé：41-70 y＞70-80 y). Conclusions: This research conclusion is that the skeletal muscle weight were similar from 41 years old to 70 years old in female older adult. But after 71 years old the skeletal muscle weight aging quickly.
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Doaei, Saeid, Naser Kalantari, Nastaran Keshavarz Mohammadi, Pantea Izadi, Maryam Gholamalizadeh, Hassan Eini-Zinab, Tuire Salonurmi et al. « The Role of FTO Genotype in the Association Between FTO Gene Expression and Anthropometric Measures in Obese and Overweight Adolescent Boys ». American Journal of Men's Health 13, no 1 (29 octobre 2018) : 155798831880811. http://dx.doi.org/10.1177/1557988318808119.
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The role of FTO genotype in the effect of FTO gene expression level on change in body mass index and body composition has not been studied. This study aimed to investigate the role of FTO genotype in the association between change in the expression level of the FTO gene with changes in anthropometric measurements in obese and overweight adolescent boys. Eighty-four boys aged 12 to 16 years participated in this longitudinal study. A bioimpedance analyzer (BIA) was used to estimate percentage of body fat (%body fat) and percentage of skeletal muscle (%skeletal muscle). The FTO gene expression level in peripheral blood mononuclear cells (PBMCs) was assessed using quantitative Real Time PCR (qPCR). The DNA samples were genotyped for the FTO gene polymorphisms by DNA sequencing. All measurements were performed at baseline and after intervention. A significant association was observed between the level of gene expression and %skeletal muscle. The gene expression fold change was significantly associated with change in %skeletal muscle in AA or AG genotype carriers (β = 0.34, p = .02). No significant association was detected between the change in FTO gene expression with change in anthropometric indices in GG genotype carriers. In conclusion, the association between FTO gene expression and body composition can be influenced by FTO genotype. Future studies are required to assess the interactions between FTO genotype, FTO gene expression in different tissues, and body composition.
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Price, T. Douglas, Corina Knipper, Gisela Grupe et Václav Smrcka. « Strontium Isotopes and Prehistoric Human Migration : The Bell Beaker Period in Central Europe ». European Journal of Archaeology 7, no 1 (2004) : 9–40. http://dx.doi.org/10.1177/1461957104047992.
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Human skeletal remains from Bell Beaker graves in southern Germany, Austria, the Czech Republic, and Hungary were analyzed for information on human migration. Strontium isotope ratios were measured in bone and tooth enamel to determine if these individuals had changed ‘geological’ residence during their lifetimes. Strontium isotopes vary among different types of rock. They enter the body through diet and are deposited in the skeleton. Tooth enamel forms during early childhood and does not change. Bone changes continually through life. Difference in the strontium isotope ratio between bone and enamel in the same individual indicates change in residence. Results from the analysis of 81 Bell Beaker individuals indicated that 51 had moved during their lifetime. Information on the geology of south-central Europe, the application of strontium isotope analysis, and the relevant Bell Beaker sites is provided along with discussion of the results of the study.
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Wall, M., F. Ragazzola, L. C. Foster, A. Form et D. N. Schmidt. « pH up-regulation as a potential mechanism for the cold-water coral <i>Lophelia pertusa</i> ; to sustain growth in aragonite undersaturated conditions ». Biogeosciences 12, no 23 (1 décembre 2015) : 6869–80. http://dx.doi.org/10.5194/bg-12-6869-2015.
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Abstract. Cold-water corals are important habitat formers in deep-water ecosystems and at high latitudes. Ocean acidification and the resulting change in aragonite saturation are expected to affect these habitats and impact coral growth. Counter to expectations, the deep water coral Lophelia pertusa has been found to be able to sustain growth even in undersaturated conditions. However, it is important to know whether such undersaturation modifies the skeleton and thus its ecosystem functioning. Here we used Synchrotron X-Ray Tomography and Raman spectroscopy to examine changes in skeleton morphology and fibre orientation. We combined the morphological assessment with boron isotope analysis to determine if changes in growth are related to changes in control of calcification pH. We compared the isotopic composition and structure formed in their natural environment to material grown in culture at lower pH conditions. Skeletal morphology is highly variable but shows no distinctive differences between natural and low pH conditions. Raman investigations found no difference in macromorphological skeletal arrangement of early mineralization zones and secondary thickening between the treatments. The δ11B analyses show that L. pertusa up-regulates the internal calcifying fluid pH (pHcf) during calcification compared to ambient seawater pH and maintains a similar elevated pHcf at increased pCO2 conditions. We suggest that as long as the energy is available to sustain the up-regulation, i.e. individuals are well fed, there is no detrimental effect to the skeletal morphology.
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Hitachi, Keisuke, Masashi Nakatani, Shiori Funasaki, Ikumi Hijikata, Mizuki Maekawa, Masahiko Honda et Kunihiro Tsuchida. « Expression Levels of Long Non-Coding RNAs Change in Models of Altered Muscle Activity and Muscle Mass ». International Journal of Molecular Sciences 21, no 5 (27 février 2020) : 1628. http://dx.doi.org/10.3390/ijms21051628.
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Skeletal muscle is a highly plastic organ that is necessary for homeostasis and health of the human body. The size of skeletal muscle changes in response to intrinsic and extrinsic stimuli. Although protein-coding RNAs including myostatin, NF-κβ, and insulin-like growth factor-1 (IGF-1), have pivotal roles in determining the skeletal muscle mass, the role of long non-coding RNAs (lncRNAs) in the regulation of skeletal muscle mass remains to be elucidated. Here, we performed expression profiling of nine skeletal muscle differentiation-related lncRNAs (DRR, DUM1, linc-MD1, linc-YY1, LncMyod, Neat1, Myoparr, Malat1, and SRA) and three genomic imprinting-related lncRNAs (Gtl2, H19, and IG-DMR) in mouse skeletal muscle. The expression levels of these lncRNAs were examined by quantitative RT-PCR in six skeletal muscle atrophy models (denervation, casting, tail suspension, dexamethasone-administration, cancer cachexia, and fasting) and two skeletal muscle hypertrophy models (mechanical overload and deficiency of the myostatin gene). Cluster analyses of these lncRNA expression levels were successfully used to categorize the muscle atrophy models into two sub-groups. In addition, the expression of Gtl2, IG-DMR, and DUM1 was altered along with changes in the skeletal muscle size. The overview of the expression levels of lncRNAs in multiple muscle atrophy and hypertrophy models provides a novel insight into the role of lncRNAs in determining the skeletal muscle mass.
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Woodward, M. I., et J. L. Cunningham. « Skeletal Accelerations Measured during Different Exercises ». Proceedings of the Institution of Mechanical Engineers, Part H : Journal of Engineering in Medicine 207, no 2 (juin 1993) : 79–85. http://dx.doi.org/10.1243/pime_proc_1993_207_274_02.
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Exercise is often suggested as a means of reducing the effects of osteoporosis in post-menopausal women. In response to an increase in physical activity, bone mass can be increased and several studies have investigated the effectiveness of different exercises in increasing bone mass. In this study we have attempted to quantify the effect of different exercises by measuring the accelerations produced during various exercises. Accelerations have been measured at the ankle of normal subjects during a series of impulsive (walking, running and walking up and down stairs) and non-impulsive (cycling) exercises. Accelerations were measured using an accelerometer attached to a stiff cuff which straps around the ankle. Signals from the accelerometer are amplified and recorded using a specially developed portable data-logging system. The principal parameters measured were the maximum change of acceleration (peak to peak) and the rate of change of acceleration. From the results it was observed that running and walking up and down stairs produced the highest peak-to-peak change (running = 8.08 g; walking downstairs = 8.11 g) and rate of change of acceleration (running = 2.14 g/s; walking downstairs = 2.07 g/s). By contrast, a non-impulsive exercise such as cycling produced relatively low values of peak-to-peak change (2.24 g) and rate of change (0.23 g/s) of acceleration.
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Aduse-Poku, Livingstone, Dheeraj Gopireddy, Mauricio Henandez, Chandana Lall, Joel Divaker, Sara Falzarano, Shahla Masood et al. « Abstract 3219 : Changes and intra-individual reliability in computed tomography image-assessed adiposity and skeletal muscles areas after breast cancer surgery ». Cancer Research 82, no 12_Supplement (15 juin 2022) : 3219. http://dx.doi.org/10.1158/1538-7445.am2022-3219.
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Abstract Background: Levels of adiposity and skeletal muscles are prognostic indicators in breast cancer patients; however, data are limited on temporal changes in body composition, particularly in different densities of muscles, before and after mastectomy. Objectives: We examined the change in CT-assessed adipose tissue and different density of skeletal muscle areas using a high-resolution segmentation method in breast cancer patients before and after surgery. Methods: This study included 50 newly-diagnosed breast cancer patients who had taken CT scans before and after surgery. We analyzed their third lumbar (L3) CT images to measure the areas of adipose tissue and five-level (from very-high-density to very-low-density) skeletal muscle components. We assessed mean and percent changes in areas using paired t-test and calculated the intra-class correlation (ICC). Results: Patients’ mean age at diagnosis was 58.3 (SD=12.5) years. The mean duration between scans was 591 (SD=537) days. There was a significant decrease in the areas of subcutaneous adipose tissue (mean change= -36.17 cm2, 11.72% decrease, p=0.029), total adipose tissue (mean change= -45.64 cm2, 10.18% decrease, p=0.032), and very-high-density muscle (mean change= -0.37 cm2, 11.08% decrease, p=0.010). The ratio of total adipose tissue and total skeletal muscle decreased from 3.67 to 3.32 after surgery (mean change= -0.36, 9.81% decrease, p=0.061). There was a strong correlation in adipose tissues and skeletal muscle areas of pre-and post-surgery scans taken within 3 years apart (ICC=0.802 to 0.999, all p<0.05), but the correlations were attenuated in scans taken >3 years apart (ICC = -0.055 to 0.738, all p>0.05). Conclusion: In this sample of breast cancer patients who have undergone surgery, there was a significant decrease in subcutaneous adipose tissues, total adipose tissues, and very-high-density muscle areas over time. Body composition assessed by CT images is reliable for a 3- year period involving breast cancer surgery. These findings serve as a baseline for prospective studies examining the impact of these changes on breast cancer outcomes. Keywords: Adipose tissue, skeletal muscle, computed tomography scans, breast cancer, surgery Citation Format: Livingstone Aduse-Poku, Dheeraj Gopireddy, Mauricio Henandez, Chandana Lall, Joel Divaker, Sara Falzarano, Shahla Masood, Weizhou Zhang, Susmita Datta, Jiang Bian, Ting-Yuan David Cheng. Changes and intra-individual reliability in computed tomography image-assessed adiposity and skeletal muscles areas after breast cancer surgery [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3219.
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Danforth, Marie Elaine. « Stature Change in Prehistoric Maya of the Southern Lowlands ». Latin American Antiquity 5, no 3 (septembre 1994) : 206–11. http://dx.doi.org/10.2307/971880.
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Since the 1950s, a decline in stature has been offered as evidence of increasing nutritional stress in prehistoric Maya populations, particularly during the Late Classic collapse. A review of the extant skeletal data, however, reveals very inconsistent support for such a decline. The primary explanation for the variation may reside in the small number of skeletal series that have representatives of more than one time period. Other possible explanations include methodological problems associated with stature reconstruction, reliability in sex determination, and variation in health response according to site size and location.
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Lee, Seung Hun, Mi Kyung Kwak, Seong Hee Ahn, Hyeonmok Kim, Yoon Young Cho, Sunghwan Suh, Kee-Ho Song, Jung-Min Koh, Jae Hyeon Kim et Beom-Jun Kim. « Change of skeletal muscle mass in patients with pheochromocytoma ». Journal of Bone and Mineral Metabolism 37, no 4 (20 septembre 2018) : 694–702. http://dx.doi.org/10.1007/s00774-018-0959-3.
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Cosman, F., J. Nieves, C. Wilkinson, D. Schnering, V. Shen et R. Lindsay. « Bone density change and biochemical indices of skeletal turnover ». Calcified Tissue International 58, no 4 (avril 1996) : 236–43. http://dx.doi.org/10.1007/bf02508642.
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Cosman, F., J. Nieves, C. Wilkinson, D. Schnering, V. Shen et R. Lindsay. « Bone Density Change and Biochemical Indices of Skeletal Turnover ». Calcified Tissue International 58, no 4 (1 avril 1996) : 236–43. http://dx.doi.org/10.1007/s002239900041.
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Collinsworth, Amy M., Sarah Zhang, William E. Kraus et George A. Truskey. « Apparent elastic modulus and hysteresis of skeletal muscle cells throughout differentiation ». American Journal of Physiology-Cell Physiology 283, no 4 (1 octobre 2002) : C1219—C1227. http://dx.doi.org/10.1152/ajpcell.00502.2001.
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The effect of differentiation on the transverse mechanical properties of mammalian myocytes was determined by using atomic force microscopy. The apparent elastic modulus increased from 11.5 ± 1.3 kPa for undifferentiated myoblasts to 45.3 ± 4.0 kPa after 8 days of differentiation ( P< 0.05). The relative contribution of viscosity, as determined from the normalized hysteresis area, ranged from 0.13 ± 0.02 to 0.21 ± 0.03 and did not change throughout differentiation. Myosin expression correlated with the apparent elastic modulus, but neither myosin nor β-tubulin were associated with hysteresis. Microtubules did not affect mechanical properties because treatment with colchicine did not alter the apparent elastic modulus or hysteresis. Treatment with cytochalasin D or 2,3-butanedione 2-monoxime led to a significant reduction in the apparent elastic modulus but no change in hysteresis. In summary, skeletal muscle cells exhibited viscoelastic behavior that changed during differentiation, yielding an increase in the transverse elastic modulus. Major contributors to changes in the transverse elastic modulus during differentiation were actin and myosin.
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Rosenbaum, Michael, Krista Vandenborne, Rochelle Goldsmith, Jean-Aime Simoneau, Steven Heymsfield, Denis R. Joanisse, Jules Hirsch et al. « Effects of experimental weight perturbation on skeletal muscle work efficiency in human subjects ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 285, no 1 (juillet 2003) : R183—R192. http://dx.doi.org/10.1152/ajpregu.00474.2002.
Texte intégralRésumé :
Maintenance of reduced or elevated body weight results in respective decreases or increases in energy expended in physical activity, defined as 24-h energy expenditure excluding resting energy expenditure and the thermic effect of feeding, beyond those attributable to weight change. We examined skeletal muscle work efficiency by graded cycle ergometry and, in some subjects, rates of gastrocnemius muscle ATP flux during exercise by magnetic resonance spectroscopy (MRS), in 30 subjects (15 males, 15 females) at initial weight and 10% below initial weight and in 8 subjects (7 males, 1 female) at initial weight and 10% above initial weight to determine whether changes in skeletal muscle work efficiency at altered body weight were correlated with changes in the energy expended in physical activity. At reduced weight, muscle work efficiency was increased in both cycle ergometry [mean (SD) change = +26.5 (26.7)%, P < 0.001] and MRS [ATP flux change = -15.2 (23.2)%, P = 0.044] studies. Weight gain resulted in decreased muscle work efficiency by ergometry [mean (SD) change = -17.8 (20.5)%, P = 0.043]. Changes in muscle efficiency at altered body weight accounted for 35% of the change in daily energy expended in physical activity.
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Ankita Agrawal, Narendra Sharma, Ranjit Kamble, Sunita Shrivastav, Shriya Prakash Murarka et Akanksha Kumar. « Comparative evaluation of Skeletal, Dental, and Soft Tissue Changes in Class II Division 1 Malocclusion Cases Treated with Twin Block and innovative Clear Block Appliance - A Prospective Interventional Study ». International Journal of Research in Pharmaceutical Sciences 12, no 2 (7 avril 2021) : 1238–46. http://dx.doi.org/10.26452/ijrps.v12i2.4666.
Texte intégralRésumé :
The present study was undertaken to evaluate and compare the skeletal, dental, and soft tissue changes in skeletal Class II division 1 cases treated with Twin Block and Clear Block appliances using a cephalogram. A total of 40 patients of age between 12-14 years were randomly divided into two equal groups. Group 1: treated with Twin Block appliance and Group 2: treated with Clear Block appliance. The pre-treatment lateral cephalogram was taken and skeletal, dental, and soft tissue parameters were evaluated and the appliance was delivered. After 8 months, another lateral cephalogram of all the cases was taken and analyzed. The pre and post-treatment values were compared between the two groups. The pre-treatment cases were almost comparable in skeletal, dental, and soft tissue features in both groups. There was a significant change in mandibular growth by SNB angle. The retrusion and extrusion of maxillary incisors as well as a proclination and extrusion of mandibular incisors were seen in group 1 while no change was observed in group 2. Treatment with Clear Block appliances has shown significant and favorable Skeletal, Dental and Soft tissue changes which are similar to already proven by the Twin Block appliance. Clear Block provides an esthetic and less bulky option for growth modification with similar results as compared to conventional Twin Block with the additional benefit of preventing lower incisor proclination.
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Ando, Shota, Takayuki Tanaka, Hiroyuki Nara et Kazuki Takizawa. « A Proposal for a Model of Change of Maximum Isometric Muscle Force in Step-Change Workload ». Journal of Robotics and Mechatronics 25, no 6 (20 décembre 2013) : 1050–59. http://dx.doi.org/10.20965/jrm.2013.p1050.
Texte intégralRésumé :
In this study, we modeled the change in maximum muscle force when a skeletal muscle is subjected to a periodic workload. The model represents an increase or decrease in the maximum muscle force exerted. It was created to evaluate the effects of our power-assist technologies on skeletal muscle strength, and we think that it can be applied to sports science. The model equation is constituted by a formula of step responses of a first-order delay system. The model input has the following four constants: the target muscle impulse when exerting force during a day in daily life, the force impulse exerted in 1 day during a period in which the target muscle was under study, the target musclemaximal strength, and the subject-specific time constant that represents the ease of change in muscle force. The output is the change in maximal strength. We confirmed the validity of the model by fitting the model to measurements obtained from experimental subjects. For this, we applied a special filter to remove noise from muscle force measurements.
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Ochôa Rodrigues, Catarina, Maria Teresa Ferreira, Vítor Matos et David Gonçalves. « “Sex change” in skeletal remains : Assessing how heat-induced changes interfere with sex estimation ». Science & ; Justice 61, no 1 (janvier 2021) : 26–36. http://dx.doi.org/10.1016/j.scijus.2020.09.007.
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Allen, D. G., G. D. Lamb et H. Westerblad. « Skeletal Muscle Fatigue : Cellular Mechanisms ». Physiological Reviews 88, no 1 (janvier 2008) : 287–332. http://dx.doi.org/10.1152/physrev.00015.2007.
Texte intégralRésumé :
Repeated, intense use of muscles leads to a decline in performance known as muscle fatigue. Many muscle properties change during fatigue including the action potential, extracellular and intracellular ions, and many intracellular metabolites. A range of mechanisms have been identified that contribute to the decline of performance. The traditional explanation, accumulation of intracellular lactate and hydrogen ions causing impaired function of the contractile proteins, is probably of limited importance in mammals. Alternative explanations that will be considered are the effects of ionic changes on the action potential, failure of SR Ca2+ release by various mechanisms, and the effects of reactive oxygen species. Many different activities lead to fatigue, and an important challenge is to identify the various mechanisms that contribute under different circumstances. Most of the mechanistic studies of fatigue are on isolated animal tissues, and another major challenge is to use the knowledge generated in these studies to identify the mechanisms of fatigue in intact animals and particularly in human diseases.
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Eftestøl, Einar, Tine Norman Alver, Kristian Gundersen et Jo C. Bruusgaard. « Overexpression of SMPX in Adult Skeletal Muscle Does not Change Skeletal Muscle Fiber Type or Size ». PLoS ONE 9, no 6 (17 juin 2014) : e99232. http://dx.doi.org/10.1371/journal.pone.0099232.
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Tindlund, Rolf S. « Skeletal Response to Maxillary Protraction in Patients with Cleft Lip and Palate before Age 10 Years ». Cleft Palate-Craniofacial Journal 31, no 4 (juillet 1994) : 295–308. http://dx.doi.org/10.1597/1545-1569_1994_031_0295_srtmpi_2.3.co_2.
Texte intégralRésumé :
Over the last 15 years, cleft lip and palate (CLP) patients with maxillary deficiency in the care of the Bergen CLP Team have received interceptive orthopedic treatment to correct anterior and posterior crossbites during the deciduous and mixed dentition periods. The present study comprises 72 subjects of various cleft types with anterior crossbite, treated to an acceptable positive overjet by maxillary protraction using a facial mask (Delaire). Lateral cephalograms were taken immediately before and after the active treatment periods. Individuals exhibiting a favorable (fair) skeletal response to the protraction were compared with those who revealed little, (poor) skeletal response. Two cephalometric variables were chosen for the evaluation of the sagittal skeletal treatment changes: (1) the sagittal maxillomandibular change (change of angle ss-n-sm [ANB]); and (2) the forward movement of the maxilla (change of distance NSP-maxp), where maxp (maxillary point) represents the anterior contour of maxilla and NSP is the perpendicular to the naslon-sella-line (NSL) through sella. A numerical change greater than or equal to the value 1.5 (degrees or mm, respectively) was classified as fair versus poor response revealing a change less than 1.5. Fair-response (favorable response) of sagittal maxillomandibular change was found in 63 % of the cases (mean increase of angle ANB was 3.3 degrees), more often when protraction started early. The length of maxilla was increased, the skeletal maxilla was moved forward 1.8 mm, the upper dentition advanced 3.6 mm, the occlusal line was clockwise rotated, and the anterior face height was increased. Similarly, fair-response of forward movement of maxilla was found in 44% of the cases (mean increase of distance NSP-maxp was 2.4 mm), more often when protraction was started early and after long treatment duration. The maxillary prognathism increased 1.8 degrees, the angle ANB increased 3 degrees, the length of maxilla increased 1.5 mm, and the upper dentition was advanced 3.7 mm. The anterior face height increased with counterclockwise rotation of the nasal line, whereas the occlusal line was clockwise rotated. A paired fair-response of both skeletal maxillomandibular change and skeletal forward movement of maxilla was found in 35% of the cases. During protraction the mean increase of maxillary prognathism was 2.1 degrees, the maxilla moved forward 3.1 mm, the maxillary dentition advanced 4.3 mm, the maxillary length increased 1.9 mm, the ANB angle increased 3.7 degrees, and the lower anterior facial height increased 3.4 mm.
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Long, Yun Chau, Emil Kostovski, Hanneke Boon, Nils Hjeltnes, Anna Krook et Ulrika Widegren. « Differential expression of metabolic genes essential for glucose and lipid metabolism in skeletal muscle from spinal cord injured subjects ». Journal of Applied Physiology 110, no 5 (mai 2011) : 1204–10. http://dx.doi.org/10.1152/japplphysiol.00686.2010.
Texte intégralRésumé :
Skeletal muscle plays an important role in the regulation of energy homeostasis; therefore, the ability of skeletal muscle to adapt and alter metabolic gene expression in response to changes in physiological demands is critical for energy balance. Individuals with cervical spinal cord lesions are characterized by tetraplegia, impaired thermoregulation, and altered skeletal muscle morphology. We characterized skeletal muscle metabolic gene expression patterns, as well as protein content, in these individuals to assess the impact of spinal cord injury on critical determinants of skeletal muscle metabolism. Our results demonstrate that mRNA levels and protein expression of skeletal muscle genes essential for glucose storage are reduced, whereas expression of glycolytic genes is reciprocally increased in individuals with spinal cord injury. Furthermore, expression of genes essential for lipid oxidation is coordinately reduced in spinal cord injured subjects, consistent with a marked reduction of mitochondrial proteins. Thus spinal cord injury resulted in a profound and tightly coordinated change in skeletal muscle metabolic gene expression program that is associated with the aberrant metabolic features of the tissue.
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Hochachka, P. W., et G. B. McClelland. « Cellular metabolic homeostasis during large-scale change in ATP turnover rates in muscles. » Journal of Experimental Biology 200, no 2 (1 janvier 1997) : 381–86. http://dx.doi.org/10.1242/jeb.200.2.381.
Texte intégralRésumé :
The term homeostasis traditionally refers to the maintenance of a relatively constant internal milieu in the face of changing environmental conditions or changing physiological function. Tissues such as skeletal and cardiac muscles must sustain very large-scale changes in ATP turnover rate during equally large changes in work. In many skeletal muscles, these changes can exceed 100-fold. In unique biological circumstances (for example, during periods of oxygen limitation, vasoconstriction and hypometabolism), tissues such as skeletal muscles may be obliged to sustain further decreases in ATP turnover rates and operate for varying periods at seriously suppressed ATP turnover rates. Examination of a number of cellular and whole-organism systems identifies ATP concentration as a key parameter of the interior milieu that is nearly universally "homeostatic'; it is common to observe no change in ATP concentration even while the change in its turnover rate can increase or decrease by two orders of magnitude. A large number of other intermediates of cellular metabolism are also regulated within narrow concentration ranges, but none seemingly as precisely as is [ATP]. In fact, the only other metabolite in aerobic energy metabolism that is seemingly as "homeostatic' is oxygen-at least in working muscles. The central regulatory question is how such homeostasis of key intermediates in pathways of energy supply and energy demand is achieved.
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Goldspink, G. « Gene expression in skeletal muscle ». Biochemical Society Transactions 30, no 2 (1 avril 2002) : 285–90. http://dx.doi.org/10.1042/bst0300285.
Texte intégralRésumé :
Muscle has an intrinsic ability to change its mass and phenotype in response to activity. This process involves quantitative and qualitative changes in gene expression, including that of the myosin heavy chain isogenes that encode different types of molecular motors. This, and the differential expression of metabolic genes, results in altered fatigue resistance and power output. The regulation of muscle mass involves autocrine as well as systemic factors. We have cloned the cDNAs of local and systemic isoforms of insulin-like growth factor-I (IGF-I) from exercised muscle. Although different isoforms are derived from the IGF-I gene by alternative splicing, the RNA transcript of one of them is only detectable following injury and/or mechanical activity. Thus this protein has been called mechano growth factor (MGF). Because of a reading-frame shift, MGF has a different 3′ sequence and a different mode of action compared with systemic or liver IGF-I. Although MGF has been called a growth factor, it may be regulated as a local repair factor.
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Di Santo, Valentina. « Ocean acidification and warming affect skeletal mineralization in a marine fish ». Proceedings of the Royal Society B : Biological Sciences 286, no 1894 (9 janvier 2019) : 20182187. http://dx.doi.org/10.1098/rspb.2018.2187.
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Ocean acidification and warming are known to alter, and in many cases decrease, calcification rates of shell and reef building marine invertebrates. However, to date, there are no datasets on the combined effect of ocean pH and temperature on skeletal mineralization of marine vertebrates, such as fishes. Here, the embryos of an oviparous marine fish, the little skate ( Leucoraja erinacea ), were developmentally acclimatized to current and increased temperature and CO 2 conditions as expected by the year 2100 (15 and 20°C, approx. 400 and 1100 µatm, respectively), in a fully crossed experimental design. Using micro-computed tomography, hydroxyapatite density was estimated in the mineralized portion of the cartilage in jaws, crura, vertebrae, denticles and pectoral fins of juvenile skates. Mineralization increased as a consequence of high CO 2 in the cartilage of crura and jaws, while temperature decreased mineralization in the pectoral fins. Mineralization affects stiffness and strength of skeletal elements linearly, with implications for feeding and locomotion performance and efficiency. This study is, to my knowledge, the first to quantify a significant change in mineralization in the skeleton of a fish and shows that changes in temperature and pH of the oceans have complex effects on fish skeletal morphology.
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Murach, Kevin, Cory Greever et Nicholas D. Luden. « Skeletal muscle architectural adaptations to marathon run training ». Applied Physiology, Nutrition, and Metabolism 40, no 1 (janvier 2015) : 99–102. http://dx.doi.org/10.1139/apnm-2014-0287.
Texte intégralRésumé :
We assessed lateral gastrocnemius (LG) and vastus lateralis (VL) architecture in 16 recreational runners before and after 12 weeks of marathon training. LG fascicle length decreased 10% while pennation angle increased 17% (p < 0.05). There was a significant correlation between diminished blood lactate levels and LG pennation angle change (r = 0.90). No changes were observed in VL. This is the first evidence that run training can modify skeletal muscle architectural features.
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Keay, Nicola, Gavin Francis, Ian Entwistle et Karen Hind. « Clinical evaluation of education relating to nutrition and skeletal loading in competitive male road cyclists at risk of relative energy deficiency in sports (RED-S) : 6-month randomised controlled trial ». BMJ Open Sport & ; Exercise Medicine 5, no 1 (mars 2019) : e000523. http://dx.doi.org/10.1136/bmjsem-2019-000523.
Texte intégralRésumé :
ObjectiveTo clinically evaluate education to improve eating behaviour and skeletal loading exercise in male cyclists at risk of poor bone health and impaired performance due to relative energy deficiency in sports.MethodsEarly race season, 50 competitive male road cyclists were matched, in pairs, based on Z-scores for lumbar spine bone mineral density (BMD). One member of each pair was randomly allocated to receive educational interventions. After the season, 45 cyclists returned for dual-energy X-ray absorptiometry scans and blood tests. Least significant change was applied to identify clinically meaningful BMD changes. Cyclists completed a follow-up sport-specific questionnaire and clinical interview to ascertain adherence to the interventions.ResultsThe questionnaire and clinical interview categorised behaviour changes as positive, negative or unchanged. Positive changes in nutrition and skeletal loading were associated with a statistically significant increase of 2.0% in lumbar spine BMD; 7 of 11 cyclists’ increases were clinically meaningful. Negative changes in both behaviours were associated with a significant decrease of 2.7% in lumbar BMD; all nine cyclists’ BMD decreases were clinically meaningful. Regarding performance, taking account of functional threshold power, changes in nutritional behaviour accounted for gains or losses of 95 British Cycling racing points. Cyclists reported psychological barriers to change in behaviours, specifically fear of negatively impacting performance.ConclusionsEducational nutritional and skeletal loading interventions can improve bone health, well-being and race performance in male cyclists over a 6-month race season. Psychological support may be required to help some athletes change behaviour.
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Connett, R. J., et C. R. Honig. « Metabolic control in exercising skeletal muscle ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 258, no 4 (1 avril 1990) : R1093. http://dx.doi.org/10.1152/ajpregu.1990.258.4.r1093-r.
Texte intégralRésumé :
Pages R288–R290: Letters to the Editor, Reply, R. J. Connett and C. R. Honig. “Metabolic control in exercising skeletal muscle.“ The sentence beginning at the very bottom of page R289 and continuing at the top of page R290 should read: ”The salient feature of the system is that the concentrations of ADP, ATP, PCr, Cr, and Pi are so interdependent through the actions of creatine kinase and adenylate kinase that the system has only one degree of freedom: measurement of change in any one of the above compounds completely defines the change in any of the others (1).”
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Connett, R. J., et C. R. Honig. « Metabolic control in exercising skeletal muscle ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 258, no 6 (1 juin 1990) : R1535. http://dx.doi.org/10.1152/ajpregu.1990.258.6.r1535-r.
Texte intégralRésumé :
Pages R288–R290: Letters to the Editor, Reply, R. J. Connett and C. R. Honig. “Metabolic control in exercising skeletal muscle.” The sentence beginning at the very bottom of page R289 and continuing at the top of page R290 should read: “The salient feature of the system is that the concentrations of ADP, ATP, PCr, Cr, and Pi are so interdependent through the actions of creatine kinase and adenylate kinase that the system has only one degree of freedom: measurement of change in any one of the above compounds completely defines the change in any of the others (1).”
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Ko, Yousun, Heeryoel Jeong, Seungwoo Khang, Jeongjin Lee, Kyung Won Kim et Beom-Jun Kim. « Change of Computed Tomography-Based Body Composition after Adrenalectomy in Patients with Pheochromocytoma ». Cancers 14, no 8 (13 avril 2022) : 1967. http://dx.doi.org/10.3390/cancers14081967.
Texte intégralRésumé :
Despite the potential biological importance of the sympathetic nervous system on fat and skeletal muscle metabolism in animal and in vitro studies, its relevance in humans remains undetermined. To clarify the influence of catecholamine excess on human body composition, we performed a retrospective longitudinal cohort study including 313 consecutive patients with histologically confirmed pheochromocytoma who underwent repeat abdominal computed tomography (CT) scans before and after adrenalectomy. Changes in CT-determined visceral fat area (VFA), subcutaneous fat area (SFA), skeletal muscle area (SMA), and skeletal muscle index (SMI) were measured at the level of the third lumbar vertebra. The mean age of all patients was 50.6 ± 13.6 years, and 171/313 (54.6%) were women. The median follow-up duration for repeat CTs was 25.0 months. VFA and SFA were 14.5% and 15.8% higher, respectively (both p < 0.001), after adrenalectomy, whereas SMA and SMI remained unchanged. Similarly, patients with visceral obesity significantly increased from 103 (32.9%) at baseline to 138 (44.1%) following surgery (p < 0.001); however, the prevalence of sarcopenia was unchanged. This study provides important clinical evidence that sympathetic hyperactivity can contribute to lipolysis in visceral and subcutaneous adipose tissues, but its impact on human skeletal muscle is unclear.
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Podbregar, Matej, Ana Ursula Gavric, Eva Podbregar, Hugon Mozina et Sebastian Stefanovic. « Red blood cell transfusion and skeletal muscle tissue oxygenation in anaemic haematologic outpatients ». Radiology and Oncology 50, no 4 (1 décembre 2016) : 449–55. http://dx.doi.org/10.1515/raon-2015-0046.
Texte intégralRésumé :
Abstract Background Stored red blood cells (RBCs) accumulate biochemical and biophysical changes, known as storage lesion. The aim of this study was to re-challenge current data that anaemia in chronically anaemic haematology patients is not associated with low skeletal muscle tissue oxygen (StO2), and that RBC storage age does not influence the tissue response after ischaemic provocation, using near-infrared spectroscopy. Patients and methods Twenty-four chronic anaemic haematology patients were included. Thenar skeletal muscle StO2 was measured at rest (basal StO2), with vascular occlusion testing (upslope StO2, maximum StO2) before and after transfusion. Results Basal StO2 was low (53% ± 7%). Average RBC storage time was 10.5 ± 3.9 days. Effects of RBC transfusions were as follows: basal StO2 and upslope StO2 did not change significantly; maximum StO2 increased compared to baseline (64 ± 14% vs. 59 ± 10%, p = 0.049). Change of basal StO2, upslope StO2 and maximum StO2 was negatively related to age of RBCs. The decrease of maximum StO2 was predicted (sensitivity 70%, specificity 100%), after receiving RBCs ≥ 10days old. Discussion Resting skeletal muscle StO2 in chronic anaemic patients is low. RBC storage time affects skeletal muscle StO2 in the resting period and after ischaemic provocation.
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Perrin, Christine. « Early diagenesis of carbonate biocrystals : isomineralogical changes in aragonite coral skeletons ». Bulletin de la Société Géologique de France 175, no 2 (1 mars 2004) : 95–106. http://dx.doi.org/10.2113/175.2.95.
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Abstract Early diagenetic changes occurring in aragonite coral skeletons were characterized at the micro- and ultra-structural scales in living and fossil scleractinian colonies, the latter of Pleistocene age. The skeleton of scleractinian corals, like all biomineralized structures, is a composite material formed by the intimate association of inorganic aragonite crystallites and organic matrices. In addition to its organo-mineral duality, the scleractinian skeleton is formed by the three-dimensional arrangement of two clearly distinct basic structural features, the centers of calcification and the fibers. The latter are typically characterized by a transverse micron-scale zonation revealing their incremental growth process. The size, geometry and three-dimensional arrangement of calcification centers and fibers are taxon-specific. The earliest diagenetic modifications of these skeletons have been clearly recognized in the older parts of living colonies. The first steps of diagenesis therefore take place only a few years after the skeleton had been secreted by the living polyps, and in the same environmental conditions. Comparisons with the uppermost living parts of the coral colonies clearly show that these first diagenetic changes are driven by the biological ultrastructural characteristics of these skeletons and are conditioned by the presence of organic envelopes interbedded with and surrounding aragonite crystallites. These first diagenetic processes induce the development of thin fringes of fibrous aragonite cements growing syntaxially on the aragonitic coral fibers, an alteration of the incremental zonation of coral fibers and also preferential diagenetic changes in the calcification centers, including dissolution of their minute internal crystals. Diagenetic patterns observed in Pleistocene coral colonies typically involve the same processes already recognized in the older skeletal parts of living colonies, suggesting that diagenesis occurs through continuous processes instead of clearly differentiated stages. Selective dissolution affects calcification centers and some growth increments of coral fibers. Alteration of the initial transverse zonation of coral fibers also occur through the development of micro-inclusions clearly seen in ultra-thin sections. Although usually thicker than those observed in the ancient skeletal parts of living colonies, syntaxial aragonite cements commonly occur in these fossil skeletons. These cements are often associated with gradual textural modifications of the underlying coral fibers, in particular the loss of the transverse micron-scale zonation. This suggests that the coral skeleton forming the substratum of diagenetic cements is progressively recrystallized in secondary aragonite. This recrystallization of coral aragonite begins at the external margin of the skeleton, just below the diagenetic cements and gradually moves towards the internal skeletal parts. Recrystallization takes place through concomitant fine-scale dissolution-precipitation processes and occurs with textural changes but no mineralogical change. The process of recrystallization is likely initiated by a biological degradation of organic skeletal matrices and can be also driven by thermodynamical constraints involving the lowering of surface free energies resulting from changes in crystal size. Alteration of skeletal organic matrix, textural changes in coral biocrystals through recrystallization and precipitation of secondary diagenetic aragonite may bias the original geochemical characteristics of coral skeletons. Although more work is needed to establish the influence of these early diagenetic processes on the geochemical signatures, it is already well known that the breakdown of organic skeletal envelopes and early recrystallization of shallow-water carbonates alter the stable isotopic composition. The widespread use of coral skeletons as environmental and climatic proxies makes strongly necessary a better understanding of these early diagenetic mechanisms and a precise characterization of the fine-scale diagenetic patterns of specimens for the optimization of geochemical interpretations. In particular, it cannot be assumed that an entire aragonitic composition can guarantee that there is no or slight diagenetic alteration.
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Young, Vanessa K. Hilliard, et Richard W. Blob. « Limb bone loading in swimming turtles : changes in loading facilitate transitions from tubular to flipper-shaped limbs during aquatic invasions ». Biology Letters 11, no 6 (juin 2015) : 20150110. http://dx.doi.org/10.1098/rsbl.2015.0110.
Texte intégralRésumé :
Members of several terrestrial vertebrate lineages have returned to nearly exclusive use of aquatic habitats. These transitions were often accompanied by changes in skeletal morphology, such as flattening of limb bone shafts. Such morphological changes might be correlated with the exposure of limb bones to altered loading. Though the environmental forces acting on the skeleton differ substantially between water and land, no empirical data exist to quantify the impact of such differences on the skeleton, either in terms of load magnitude or regime. To test how locomotor loads change between water and land, we compared in vivo strains from femora of turtles ( Trachemys scripta ) during swimming and terrestrial walking. As expected, strain magnitudes were much lower (by 67.9%) during swimming than during walking. However, the loading regime of the femur also changed between environments: torsional strains are high during walking, but torsion is largely eliminated during swimming. Changes in loading regime between environments may have enabled evolutionary shifts to hydrodynamically advantageous flattened limb bones in highly aquatic species. Although circular cross sections are optimal for resisting torsional loads, the removal of torsion would reduce the advantage of tubular shapes, facilitating the evolution of flattened limbs.
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Rassier, D. E., B. R. MacIntosh et W. Herzog. « Length dependence of active force production in skeletal muscle ». Journal of Applied Physiology 86, no 5 (1 mai 1999) : 1445–57. http://dx.doi.org/10.1152/jappl.1999.86.5.1445.
Texte intégralRésumé :
The sliding filament and cross-bridge theories of muscle contraction provide discrete predictions of the tetanic force-length relationship of skeletal muscle that have been tested experimentally. The active force generated by a maximally activated single fiber (with sarcomere length control) is maximal when the filament overlap is optimized and is proportionally decreased when overlap is diminished. The force-length relationship is a static property of skeletal muscle and, therefore, it does not predict the consequences of dynamic contractions. Changes in sarcomere length during muscle contraction result in modulation of the active force that is not necessarily predicted by the cross-bridge theory. The results of in vivo studies of the force-length relationship suggest that muscles that operate on the ascending limb of the force-length relationship typically function in stretch-shortening cycle contractions, and muscles that operate on the descending limb typically function in shorten-stretch cycle contractions. The joint moments produced by a muscle depend on the moment arm and the sarcomere length of the muscle. Moment arm magnitude also affects the excursion (length change) of a muscle for a given change in joint angle, and the number of sarcomeres arranged in series within a muscle fiber determines the sarcomere length change associated with a given excursion.
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Liu, X., N. Zhang, B. Sung et B. Wang. « Time-specific effects of acute eccentric exercise on myostatin, follistatin and decorin in the circulation and skeletal muscle in rats ». Physiological Research 71, no 6 (13 octobre 2022) : 835–48. http://dx.doi.org/10.33549/physiolres.934833.
Texte intégralRésumé :
Myostatin (MSTN), an important negative regulator of skeletal muscle, plays an important role in skeletal muscle health. In previous study, we found that the expression of MSTN was different during skeletal muscle injury repair. Therefore, we explored the expression changes of MSTN at different time points during skeletal muscle injury repair after eccentric exercise. In addition, MSTN is regulated by follistatin (FST) and decorin (DCN) in vivo, so our study examined the time-specific changes of FST, DCN and MSTN in the circulation and skeletal muscle during skeletal muscle injury repair after eccentric exercise, and to explore the reasons for the changes of MSTN in the process of exercise-induced muscle injury repair, to provide a basis for promoting muscle injury repair. The rats performed one-time eccentric exercise. Blood and skeletal muscle were collected at the corresponding time points, respectively immediate after exercise (D0), one day (D1), two days (D2), three days (D3), seven days (W1) and fourteen days (W2) after exercise (n=8). The levels of MSTN, FST, DCN in serum and mRNA and protein expression in muscle were detected. MSTN changes in the blood and changes in DCN and FST showed the opposite trend, except immediately after exercise. The change trends of mRNA and protein of gastrocnemius DCN and MSTN are inconsistent, there is post-transcriptional regulation of MSTN and DCN in gastrocnemius. Acute eccentric exercise might stimulate the secretion of DCN and FST into the circulation and inhibit MSTN. MSTN may be regulated by FST and DCN after acute eccentric exercise.
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Rose, Christopher S. « The cellular basis of cartilage growth and shape change in larval and metamorphosing Xenopus frogs ». PLOS ONE 18, no 1 (12 janvier 2023) : e0277110. http://dx.doi.org/10.1371/journal.pone.0277110.
Texte intégralRésumé :
As the first and sometimes only skeletal tissue to appear, cartilage plays a fundamental role in the development and evolution of vertebrate body shapes. This is especially true for amphibians whose largely cartilaginous feeding skeleton exhibits unparalleled ontogenetic and phylogenetic diversification as a consequence of metamorphosis. Fully understanding the evolutionary history, evolvability and regenerative potential of cartilage requires in-depth analysis of how chondrocytes drive growth and shape change. This study is a cell-level description of the larval growth and postembryonic shape change of major cartilages of the feeding skeleton of a metamorphosing amphibian. Histology and immunohistochemistry are used to describe and quantify patterns and trends in chondrocyte size, shape, division, death, and arrangement, and in percent matrix from hatchling to froglet for the lower jaw, hyoid and branchial arch cartilages of Xenopus laevis. The results are interpreted and integrated into programs of cell behaviors that account for the larval growth and histology, and metamorphic remodeling of each element. These programs provide a baseline for investigating hormone-mediated remodeling, cartilage regeneration, and intrinsic shape regulating mechanisms. These programs also contain four features not previously described in vertebrates: hypertrophied chondrocytes being rejuvenated by rapid cell cycling to a prechondrogenic size and shape; chondrocytes dividing and rearranging to reshape a cartilage; cartilage that lacks a perichondrium and grows at single-cell dimensions; and an adult cartilage forming de novo in the center of a resorbing larval one. Also, the unexpected superimposition of cell behaviors for shape change onto ones for larval growth and the unprecedented exploitation of very large and small cell sizes provide new directions for investigating the development and evolution of skeletal shape and metamorphic ontogenies.
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McElwain, Jennifer C., et William G. Chaloner. « The Fossil Cuticle as a Skeletal Record of Environmental Change ». PALAIOS 11, no 4 (août 1996) : 376. http://dx.doi.org/10.2307/3515247.
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Zuo, Li, et Denethi Wijegunawardana. « Does Heat Preconditioning Change Skeletal Muscle Function In Animal Model ? » Medicine & ; Science in Sports & ; Exercise 53, no 8S (août 2021) : 109. http://dx.doi.org/10.1249/01.mss.0000760400.78850.0b.
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Barclay, J. K., S. A. Reading, C. L. Murrant et N. E. Woodley. « Inotropic effects on mammalian skeletal muscle change with contraction frequency ». Canadian Journal of Physiology and Pharmacology 81, no 8 (1 août 2003) : 753–58. http://dx.doi.org/10.1139/y03-031.
Texte intégralRésumé :
Over the last decade, we have attempted to determine if mammalian skeletal muscle's steady-level force development as established by mechanical and stimulation parameters can be increased or decreased by physiological signals. In these experiments, nitric oxide (NO), endothelin-1 (ET-1), adenosine (Ado), and β-adrenergic agonists (β) modified force production in the soleus and (or) the extensor digitorum longus (EDL) of the mouse. NO and β increased the force produced by 0.5-s tetanic contractions at 0.6 contractions/min in both muscles. While EDL did not respond to either Ado or ET-1, the developed force of the soleus was amplified by Ado but attenuated by ET-1. Increased cAMP analogue concentrations amplified developed force in both muscles, but a cGMP analogue had no effect on either muscle. Following an increase in the contraction frequency of the soleus, the increased force in response to NO disappeared, as did the decreased force to ET-1. The increase in force due to a cAMP analogue disappeared during fatigue but reappeared quickly during recovery. Thus, steady-level developed force can be modified by a number of substances that can be released from locations in the body or muscle. The response to a given compound is determined by a complex interaction of metabolic and intracellular signals on the force-generating cascade.Key words: endothelium-derived factors, cAMP, cGMP, isoproterenol, adenosine.