Tesi: "Skeletal Adaptation"

1

Ellman, Rachel. "Skeletal adaptation to reduced mechanical loading". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/107612.

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Abstract (sommario):

Thesis: Ph. D. in Medical Engineering and Bioastronautics, Harvard-MIT Program in Health Sciences and Technology, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 126-139).
Bone adapts its mass and architecture in response to its mechanical environment. Yet control of this process by mechanical cues is poorly understood, particularly for unloading. Defining the fundamental mechano-regulation of bone adaptation is critical for the better understanding and mitigation of bone loss in astronauts as well as clinical conditions such as spinal cord injury, stroke, muscular dystrophy, and bed rest. The overall goal of this work was to study skeletal adaptation to varying amounts of reduced loading to help delineate the relationship between mechanical stimuli and skeletal adaptation. We first examined the relative contribution of muscle and gravitational forces to the maintenance of skeletal health in mice, using botulinum toxin (BTX) to induce muscle paralysis and hindlimb unloading to eliminate external loading on the hindlimbs, alone and in combination. BTX led to greater bone loss than hindlimb unloading, while the combination of interventions led to the most detrimental effects overall, suggesting that both muscle and gravitational forces play a role in skeletal maintenance, with greater contributions from muscle forces. We then characterized skeletal adaptation to controlled reductions in mechanical loading of varying degrees employing a novel model that enables long-term exposure of mice to partial weightbearing (PWB). We found that declines in bone mass and architecture were linearly related to the degree of unloading. Even mice bearing 70% of their body weight exhibited significant bone loss, suggesting that the gravity of the moon (0.16 G) and Mars (0.38 G) will not be sufficient to prevent bone loss on future exploration missions. Finally, since bone remodeling is highly site-specific, we used gait analysis and inverse dynamics to determine the mechanical environment during PWB, and then developed a finite element model of the tibia to resolve the local strain-related stimulus proposed to drive changes in bone mass. We found modest correlations between cortical bone architecture at different PWB levels and strain energy density. Altogether this work provides a critical foundation and rationale for future studies that incorporate detailed quantification of the mechanical stimuli and longitudinal changes in bone architecture to further advance our understanding of the skeletal response to reduced loading.
by Rachel Ellman.
Ph. D. in Medical Engineering and Bioastronautics

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2

Eliman, Rachel. "Skeletal adaptation to reduced mechanical loading". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/95861.

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Abstract (sommario):

Thesis: Ph. D., Harvard-MIT Program in Health Sciences and Technology, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 126-139).
Bone adapts its mass and architecture in response to its mechanical environment. Yet control of this process by mechanical cues is poorly understood, particularly for unloading. Defining the fundamental mechanoregulation of bone adaptation is critical for the better understanding and mitigation of bone loss in astronauts as well as clinical conditions such as spinal cord injury, stroke, muscular dystrophy, and bed rest. The overall goal of this work was to study skeletal adaptation to varying amounts of reduced loading to help delineate the relationship between mechanical stimuli and skeletal adaptation. We first examined the relative contribution of muscle and gravitational forces to the maintenance of skeletal health in mice, using botulinum toxin (BTX) to induce muscle paralysis and hindlimb unloading to eliminate external loading on the hindlimbs, alone and in combination. BTX led to greater bone loss than hindlimb unloading, while the combination of interventions led to the most detrimental effects overall, suggesting that both muscle and gravitational forces play a role in skeletal maintenance, with greater contributions from muscle forces. We then characterized skeletal adaptation to controlled reductions in mechanical loading of varying degrees employing a novel model that enables long-term exposure of mice to partial weightbearing (PWB). We found that declines in bone mass and architecture were linearly related to the degree of unloading. Even mice bearing 70% of their body weight exhibited significant bone loss, suggesting that the gravity of the moon (0.16 G) and Mars (0.38 G) will not be sufficient to prevent bone loss on future exploration missions. Finally, since bone remodeling is highly site-specific, we used gait analysis and inverse dynamics to determine the mechanical environment during PWB, and then developed a finite element model of the tibia to resolve the local strain-related stimulus proposed to drive changes in bone mass. We found modest correlations between cortical bone architecture at different PWB levels and strain energy density. Altogether this work provides a critical foundation and rationale for future studies that incorporate detailed quantification of the mechanical stimuli and longitudinal changes in bone architecture to further advance our understanding of the skeletal response to reduced loading.
by Rachel Eliman.
Ph. D.

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3

Kohn, Tertius A. "Characteristics and adaptation of skeletal muscle to endurance exercise". Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/16517.

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Abstract (sommario):

Thesis (PhD)--University of Stellenbosch, 2005.
ENGLISH ABSTRACT: Skeletal muscle adapts to stimuli by modifying structural and metabolic protein expression. Furthermore, a muscle group may vary within itself to accommodate specialisation in regions. Structural and metabolic characteristics of an individual are regulated partly by genotype, but contraction duration and intensity may play a greater role in muscle phenotype. The aims of this dissertation were to investigate: structural and metabolic regionalisation in a muscle group, possible relationships between training volume and intensity and hybrid fibres, muscle characteristics of athletes from two different ethnic groups, and muscle adaptation in already well-trained athletes subjected to high intensity interval training. Myosin heavy chain (MHC) isoform content and citrate synthase (CS) activities were measured in the Quadriceps femoris (QF) muscle of 18 female rats. Muscle was divided into superficial, middle and deep, distal, central and proximal parts. MHC IIb and IIx were more abundant in superficial regions (P < 0.05) with low CS activities compared to deeper parts. Isoform content varied along the length of deep regions. This study showed that the QF has regional specialisation. Therefore, standardisation of sampling site is important. Hybrid fibre proportions in muscle biopsies of 12 middle distance runners and 12 non-runners were investigated. MHC IIa/IIx correlated with training volume/week in runners (r = -0.66, P < 0.05) and MHC IIa/IIx correlated with exercise hours/week in non-runners (r = -0.72, P < 0.01). Average preferred racing distance (PRDA) correlated better with MHC IIa/IIx in runners (r = -0.85, P < 0.001). MHC IIa/IIx may therefore be more closely related to exercise intensity than previously thought. Fibre type characteristics and performance markers were investigated in 13 Xhosa and 13 Caucasian distance runners, matched for performance, training volume and PRDA. Xhosa runners had less MHC I and more MHC IIa fibres in muscle biopsies than Caucasian runners (P < 0.05). Xhosa runners had lower plasma lactate at 80% peak treadmill speed (PTS) (P < 0.05), but higher lactate dehydrogenase (LDH) (P < 0.01) and phosphofructokinase (P = 0.07) activities in homogenate muscle samples. LDH activities in MHC I (P = 0.05) and IIa (P < 0.05) fibre pools were higher in Xhosa runners. Xhosa athletes may thus have a genetic advantage or they may have adapted to running at a higher intensity. Six weeks of individually standardised high intensity interval treadmill training (HIIT) were investigated in 15 well-trained runners. PTS increased after HIIT (P < 0.01), while maximum oxygen consumption (VO2max) only showed a tendency to have increased as a result of HIIT (P = 0.06). Sub-maximal tests showed lower plasma lactate at 64% PTS (P = 0.06), with lower heart rates at workloads from 64% to 80% PTS (P < 0.01) after HIIT. No changes were observed for cross-sectional area, capillary supply and enzyme activities in homogenates muscle samples. LDH activity showed a trend (P = 0.06) to have increased in MHC IIa pools after HIIT. Higher HIIT speed was related to decreases in MHC I fibres, but increases in MHC IIa/IIx fibres (r = -0.70 and r = 0.68, respectively, P < 0.05). Therefore, HIIT may alter muscle fibre composition in well-trained runners, with a concomitant improvement in performance markers.
AFRIKAANSE OPSOMMING: Skeletspier kan adapteer deur strukturele en metaboliese protein ekspressie te verander as gevolg van stimulante. ‘n Spiergroep kan ook intern verskil om spesialisering in spierdele toe te laat. Strukturele en metaboliese karaktereienskappe van ‘n individu word deels gereguleer deur gene, maar kontraksie tydperk en intensiteit mag ‘n groter rol speel in spierfenotipe. Die doelwitte van hierdie tesis was om ondersoek in te stel in: strukturele en metaboliese eienskappe in spiergroepstreke, moontlike verhoudings tussen oefeningsvolume of intensiteit en baster vesels, spier eienskappe in atlete van twee etniese groepe, en spier adaptasie in goed geoefende atlete blootgestel aan hoë intensiteit interval oefening. Miosien swaar ketting (MSK) isovorm inhoud en sitraat sintase (SS) aktiwiteite is gemeet in die Quadriceps femoris (QF) spier van 18 wyfie rotte. Spiere was opgedeel in oppervlakkig, middel en diep, asook distaal, sentraal en proksimale dele. MSK IIb en IIx was meer oorvloedig in oppervlakkige dele (P < 0.05) met lae SS aktiwiteite in vergelyking met dieper dele. Isovorm inhoud het ook verskil oor die lengte van diep dele. Dus bevat die QF gespesialiseerde streke en is die area van monsterneming belangrik. Baster vesel proporsies is ondersoek in spiermonsters van 12 middel afstand hardlopers en 12 niehardlopers. MSK IIa/IIx van hardlopers het met oefeningsvolume/week gekorreleer (r = -0.66, P < 0.05), asook MSK IIa/IIx van nie-hardlopers met oefeningsure/week (r = -0.72, P < 0.01). Gemiddelde voorkeur wedloop afstand (VWAG) het beter met MSK IIa/IIx gekorreleer in hardlopers (r = -0.85, P < 0.001). MSK IIa/IIx mag dus meer verwant wees aan oefeningsintensiteit. Veseltipe eienskappe en prestasie merkers was ondersoek in 13 Xhosa en 13 Caucasian langafstand atlete, geëweknie vir prestasie, oefeningsvolume en VMAG. Xhosa hardlopers het minder tipe I en meer tipe IIA vesels in hul spiermonsters gehad as die Caucasian hardlopers (P < 0.05). Xhosa hardlopers het laer plasma laktaat by 80% van hul maksimale trapmeul spoed (MTS) (P < 0.05), maar hoër laktaat dihidrogenase (LDH) (P < 0.01) en fosfofruktokinase (P = 0.07) aktiwiteite in homogene spiermonsters gehad. LDH aktiwiteite in MSK I (P = 0.05) en IIa (P < 0.05) veselbondels was hoër in Xhosa hardlopers. Xhosa atlete mag dus ‘n genetiese voorsprong geniet, of hulle het geadapteer om by hoër intensiteite te hardloop. Ses weke van geïndividualiseerde gestandardiseerde hoë intensiteit interval trapmeul oefening (HIIT) was ondersoek in 15 goed geoefende hardlopers. MTS het verhoog na HIIT (P < 0.01), en maksimale surrstof verbruik (VO2max) het ‘n neiging getoon om te verhoog het na HIIT (P = 0.07). Submaksimale toetse het laer plasma laktaat by 64% MTS getoon (P = 0.06), met laer harttempos by werkladings 64% tot 80% MTS (P < 0.01). Geen veranderings was gemerk vir deursnit area, kapillêre toevoer en ensiem aktiwiteite in homogene spiermonsters nie. LDH aktiwiteit het ‘n neiging getoon om te verhoog het (P = 0.06) in MSK IIa veselbondels na HIIT. Hoër HIIT snelhede was verwant aan ‘n daling in MSK I vesels, maar ‘n verhoging in MSK IIa/IIx vesels (r = -0.70 en r = 0.68, respektiwelik, P < 0.05). HIIT mag dus spier veseltipe verander in goed geoefende hardlopers, met gevolglike verbetering in prestasie merkers.

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4

Beckitt, Timothy. "Skeletal muscle adaptation following a supervised exercise programme for claudication". Thesis, University of Bristol, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539766.

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5

Wiebe, Peter N., e res cand@acu edu au. "Effects of Different Loading Intensities on Skeletal Adaptation to Exercise in Prepubertal Girls". Australian Catholic University. School of Exercise Science, 2004. http://dlibrary.acu.edu.au/digitaltheses/public/adt-acuvp62.29082005.

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This study involved a 28-week school-based exercise trial of single-leg drop-landing exercise with 42 girls (Tanner stage 1; 6-10 yr old) randomly assigned to control (C), low-drop (LD) or high-drop(HD) exercise groups. The latter two groups performed single-leg drop-landings (3 sessions.wk-1 and 50 landings.session-1) from 14cm and 28cm, respectively using the non-dominant leg. Single-leg peak ground-reaction impact forces (PGRIF) in a sub-sample ranged between 2.5 – 4.4 x body-weight (BW). No differences (p>0.05) among groups at baseline for age, stature, lean tissue mass (LTM - DXA - Lunar 3.6-DPX), leisure time physical activity or average daily calcium intake were detected. No significant within group changes for between leg differences from baseline to post-training and no significant differences among groups at baseline, or in magnitude of change for any of the dominant or non-dominant (loaded) leg bone mineral content (BMC g) measures determined by DXA – loaded leg total - 19.06, 25.5, 25.46 [p=.156], femoral neck - 0.14, 0.11, 0.15 [p=.959], greater trochanter - 0.37, 0.06, 0.26 [p=.733], mid femoral shaft - 3.87, 3.87, 3.42 [p=.677] for the C, LD and HD groups, respectively, after adjusting for the covariates baseline body and fat mass, and change in LTM (ANCOVA) were observed. Similarly, following ANCOVA adjustments no significant differences for changes in calcaneal speed of sound and broadband ultrasound attenuation (CUBA Clinical), DXA derived changes in femoral neck (-0.009, 0.033, -0.009; p=.189) and total MFS (0.029, 0.041, 0.053; p=.447) volumetric BMD (g.cm-3), or MFS cortical volumetric BMD, the latter derived by a new technique combining MRI and DXA were identified. TBBMC changed by 79.6g-C, 100.2g-LD and 91.9g-HD (p=.339). Combining data from both exercise groups to increase statistical power produced similar results. No significant within group changes for between leg differences from baseline to post-training and no significant differences among groups at baseline, or in magnitude of change for any of the dominant or non-dominant (loaded) leg bone geometrical (area cm2) determined by MRI using ANALYZE® software of proximal - 22.18, 12.91, 19.86 [p=.248], mid - 19.83, 15.91, 19.64 [p=.233], or distal - 14.78, 16.07, 13.35 [p=.792], slice cortical area for the C, LD and HD groups, respectively, after adjusting for the covariates baseline body and fat mass, and change in LTM (ANCOVA) were detected. Similarly there were no significant biomechanical cross sectional moment of inertia (CSMI cm4) changes determined by Scion Image® (Frederick, Maryland: Version-Beta 3B) and a custom macro program of proximal - 896, 815, 649 [p=.415], mid - 1054, 806, 1087 [p=.471], or distal - 1197, 1079, 966 [p=.606], slice CSMI for the C, LD and HD groups, respectively after adjusting for the same covariates. In contrast to some recent reports, our findings suggest that strictly controlled uni-modal; uni-directional single-leg drop-landing exercises involving low-moderate peak ground-reaction impact forces are not osteogenic in the developing prepubertal female skeleton.

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6

Hirschberg, Jens. "Simulations of mechanical adaptation and their relationship to stress bearing in skeletal tissue". University of Western Australia. School of Anatomy and Human Biology, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0095.

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[Truncated abstract] In this work a computer simulation program, similar to a finite element program, is used to study the relationship between skeletal tissue structure and function. Though other factors affect the shape of bone (e.g., genetics, hormones, blood supply), the skeleton adapts its shape mainly in response to the mechanical environment to which it is exposed throughout life. The specific relationship between the mechanical environment and the mechanical adaptation response of the skeleton is reviewed. Theories of mechanical adaptation are applied to the sites of tendon attachment to bone (entheses), the adaptation of generalised trabecular bone (i.e., Wolff’s Law of trabecular architecture), sesamoid bones that are often found where a tendon wraps around a bony pulley, and the internal trabecular structure of a whole bony sesamoid such as the patella. The relative importance of compression rather than tension in bone adaptation theories is still not fully understood. Some mechanical adaptation theories suggest that an overwhelming tensile stress at a skeletal location does not stimulate bone deposition, but would instead lead to bone resorption. The skeletal locations studied in this work were chosen because they have been proposed to be in tension. Computer simulations involving models are an ideal method to analyse the mechanical environment of a skeletal location. They are able to determine the mechanical stresses at, and the stress patterns around, complex biological situations. This study uses a two dimensional computer simulation program, Fast Lagrangian Analysis of Continua (Flac), to analyse the stress at the skeletal locations, and to test theories of mechanical adaptation over time by simulating physiological adaptation. The initial purpose of this study is to examine the stress in the skeletal tissue in generalised trabeculae, anatomical sites where a tendon wraps around a bony pulley, in the trabecular networks that fill the patella, and at tendon attachments. A secondary purpose, that follows directly from the first, is to relate the results of these initial stress analyses to existing and hypothetical skeletal tissue remodelling theories, to suggest how the complex skeletal structures might be generated solely in response to their mechanical environment. The term “remodelling” is used throughout this work to refer to mechanical adaptation of bone, usually at a surface of bone, rather than the internal regeneration of osteons (Haversion systems)

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7

Chen, Ting. "LKB1 Regulation of High-Fat Diet-induced Adaptation in Mouse Skeletal Muscle". BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6682.

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Ad libitum high-fat diet (HFD)-induced obesity leads to insulin resistance in skeletal muscle, altered gene expression, and altered growth signaling, all of which contributes to pathological changes in metabolism. Liver kinase B1 (LKB1) is an important metabolism regulator. The purpose of this dissertation was to understand how knocking out LKB1 influences HFD induced adaptations in mouse skeletal muscle. To do so, control and skeletal muscle LKB1 knock-out (LKB1-KO) mice were put on either standard diet (STD) or HFD for 1 week or 14 weeks, or put on the HFD for 14 weeks and then switched to STD for 1 week (switched diet). The major differences in adaptation in the LKB1-KO mice include: 1) lower fasting blood glucose levels but impaired glucose tolerance compared to WT mice (although conflicting results are generated if the data is not normalized to fasting blood glucose levels), 2) altered expression of 16 HFD-induced genes, and 3) decreased muscle weight. The lower fasting blood glucose in LKB1-KO mice was likely due to elevated serum insulin levels, and the impaired glucose tolerance was associated with decreased phosphorylation of TBC1D1, an important regulator of insulin stimulated glucose uptake. 16 potential important target genes (metabolism, mitochondrial, cytoskeleton, cell cycle, cell-cell interactions, enzyme, ion channel) were identified in the context of HFD feeding and LKB1-KO. These genes were quantified by RT-PCR and grouped according to changes in their patterns of expression among the different groups. Among several other interesting changes in gene expression, the muscle growth-related protein, Ky was not affected by short-term HFD, but increased after long-term HFD, and did not decrease after switched diet, showing that its expression may be an important long-term adaptation to HFD. LKB1-KO promoted anabolic signaling through increasing t-eIF2α and eIF4E expression, and promoted protein degradation through increasing protein ubiquitination. Because the degradation is the main effect and lead to muscle weight decrease. The effect of HFD and/or LKB1-KO on the LKB1-AMPK system was also determined. The results showed that knocking-out LKB1 decreased AMPK activity, decreased nuclear distribution for AMPK α2 and increased AMPK α1 expression. Long-term HFD increased t-AMPK expression in LKB1-KO mice, decreased the cytoplasm p-AMPK and nuclear p/t-AMPK ratio in CON mice. Together the findings of this dissertation demonstrated HFD induced glucose/insulin tolerance, while LKB1-KO had a controversial effect on glucose/insulin sensitivity. Both HFD and LKB1-KO affect AMPK expression and cellular location, while LKB1-KO also affects AMPK activity. LKB1-KO promoted protein degradation through ubiquitination in skeletal muscle.

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8

Isaacs, Ashwin Wayne. "Muscle damage and adaptation in response to plyometric jumping". Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20384.

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Abstract (sommario):

Thesis (MSc)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: The aim of the study was to investigate skeletal muscle changes induced by an acute bout of plyometric exercise before and after plyometric training. The study consisted of an acute study and training intervention study. The acute study, investigated whether direct evidence of ultrastructural damage and identification of indirect factors were more evident in subjects presenting with rhabdomyolysis. Moreover the training intervention study investigated whether plyometric training would protect the muscle from ultrastructural damage and rhabdomyolysis. During the acute intervention, twenty six healthy untrained individuals completed an acute bout of plyometric exercise (10 x 10 squat-jumps, 1 min rest). After, thirteen subjects continued with the training intervention. Eight of these subjects completed 8 weeks of plyometric jump training, while five subjects were instructed to rest from physical activity for 8 weeks. Seven days after the final training session the training and rest group repeated a second acute bout of plyometric exercise. Acute Study: Creatine kinase (CK) activity increased significantly following the single bout of plyometric exercise in all subjects (baseline: 129 to day 4: 5348 U/l). This was accompanied by an increase in perceived pain, C-reactive protein (CRP) a marker of inflammation as well as white blood cells (WBCs). Electron micrographs of muscle biopsies taken 3 days post exercise showed evidence of ultrasructural damage and membrane damage was apparent by immunofluorescence by the loss of dystrophin staining. A stretch of the c-terminus of titin was observed by immunogold, and western blot analysis indicated an increase in calpain-3 autolysis. Based on individual CK responses (CK range: 153-71,024 U/L at 4days after exercise) the twenty six subjects were divided into two groups, namely the high (n=10) and low responders (n=16). Training intervention: Following training the trained group did not experience: a rise of CK activity (110.0 U/l), perceived pain, CRP, WBCs, Z-line streaming, a stretch of titin or calpain-3 activation; while in the control group only two subjects presented with Z-line streaming. The results indicate that high responders have a more pronounced inflammatory response compared to low responders after eccentric exercise, therefore more WBCs and more specifically neutrophils are recruited to damaged areas resulting in greater membrane damage by respiratory burst in high responders. This damage can be limited with training by remodelling sarcomeric proteins via calpain activation resulting in the stable assembly of proteins in the sarcomere preventing the release of proteins.
AFRIKAANSE OPSOMMING: Die doel van die studie was om skeletspier veranderinge wat teweeggebring is deur voor en na afloop van akute pleometriese oefening, te ondersoek. Die studie bestaan uit ‘n akute intervensie en ‘n oefeningsintervensie gedeelte. Die akute intervensie het ondersoek ingestel na die direkte bewyse van ultrastrukturele skade en identifikasie van indirekte faktore meer sigbaar is in proefpersone wat met rhabdomiolose presenteer. Meerso het die oefningsintervensie die moontlikheid dat pleometriese oefening die spier van ultrastrukturele skade en rhabdomiolose beskerm, ondersoek. Tydens die akute intervensie is 26 gesonde ongeoefende individue die akute pleometriese oefeningsessie (10 x 10 hurkspronge, 1 min rus) voltooi. Hierna het 13 proefpersone voortgegaan met die oefeningsintervensie. Agt van hierdie proefpersone het agt weke pleometriese sprongsessie oefeninge voltooi, terwyl vyf proefpersone gevra is om vir 8 weke geen oefeninge te doen nie. Sewe dae na afloop van die finale oefeningssessie het die oefening en kontrole groep in ‘n tweede herhaalde akute pleometriese oefeningsessie deelgeneem. Akute intervensie: kreatienkinase (KK) aktiwiteit het betekenisvol verhoog na die enkel pleometriese oefeningsessie in all proefpersone (basislyn: 129 tot op dag vier: 5348 U/l). Hierdie is vergesel met ‘n toename in die persepsie van pyn, c-reaktiewe proteïen (CRP) ‘n merker van inflammasie sowel as witbloedselle (WBS). Elektronmikrograwe van spierbiopsies wat geneem is drie dae na afloop van die oefeninge, het tekens van ultrastrukturele skade en membraanskade getoon wat ook deur immunofluoresensie duidelik warneembaar was deur die verlies van distrofienverkleuring. ‘n Verrekking van die c-terminus van titin is ook waargeneem deur middel van immunogold. Westernblot analyse het ‘n toename in calpain-3 outolise getoon. Gegrond op individuele KK response (KK grense: 153-71,024 U/L na vier dae post oefening) is 26 proefpersone verdeel in twee groepe naamlik ‘n hoë (n=10) en lae responders (n=16). Oefeningintervensie:: Na oefening het die geoefende groep nie ‘n toename in KK aktiwiteit getoon nie (KK aktiwiteit (110.0 U/l)), pynervaring, CRP, WBS, Z-lynstroming, ‘n strekking van titin of calpain-3 aktivering; terwyl in die kontrole groep daar slegs twee proefpersone met Z-lynstroming geïdentifiseer is. Die resultate wyse daarop dat hoë responders ‘n meer uitgesproke inflammatoriese reaksie toon vergeleke met die lae responders na afloop van essentriese oefening. Daar word dus meer WBS en spesifiek meer neutrofiele na beskadigde areas gelokaliseer wat in grootter membraanskade deur respiratoriese inspanning in die hoë responders. Hierdie skade kan beperk word deur oefening waardeur hermodulering van sarkomeriese proteïene via calpain aktivering tot stabiele rangskiking van proteïene in die sarcomere lei en daardeur proteïen vrystelling verhinder.
The NRF for financial assistance

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9

Owino, Dorcas Vivian Apiyo. "Evaluation of role of paracrine/autocrine IGF-1 system in skeletal muscle adaptation". Thesis, University College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406510.

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10

Varley, I. "Association of genotype with bone metabolism, skeletal adaptation and stress fracture injury occurrence". Thesis, Nottingham Trent University, 2014. http://irep.ntu.ac.uk/id/eprint/223/.

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Abstract (sommario):

Positive changes in bone metabolism, structural characteristics, size and mass are commonly associated with weight-bearing exercise. Despite this, negative effects of exercise on bone phenotypes, such as stress fracture injuries have been reported. Little is known about the extent of the genetic mediation of changes in bone characteristics, stress fracture injury and bone resorption in response to exercise. Accordingly, this thesis investigated: the genotype dependent changes in bone phenotypes in academy footballers before and after an increase in training volume; genetic associations with stress fracture injury in elite athletes and a preliminary investigation into genetic associations with bone resorption following 120 min of treadmill running. The tibial bone characteristics of 80, full-time academy footballers was determined using pQCT before and after 12 weeks of increased volume football training. Genetic associations with baseline, post increased training and change in bone characteristics were then determined. Secondly, radiologically confirmed stress fracture history was reported in 518 elite athletes, forming the Stress Fracture Elite Athlete (SFEA) cohort. Genetic associations were analysed for the whole group, and were also sub-stratified. Finally, recreationally active healthy male participants (n=42) performed a 120 min run at 70% O2max. Genetic associations with bone resorption at baseline, immediately, 24, 48 and 72 hours post run were investigated. SNPs in the proximity of genes in P2X7R and the RANK/RANKL/OPG signalling and Wnt signalling pathways were associated with bone phenotypes before and following 12 weeks of increased volume football training (P<0.05). SNPs in close proximity to SOST, P2X7R, RANK, RANKL, OPG, Bradykinin and VDR genes were associated with stress fracture injury in the whole cohort and in various sub-classifications of elite athletes (P<0.05). No associations were shown in bone resorption prior to, immediately following or in the 3 days following 120 min of treadmill running. The data suggest a role for specific genes and SNPs in bone phenotypic changes as a result of exercise training and in the susceptibility to stress fracture injury. The association of SNPs in P2X7R and the RANK/RANKL/OPG signalling and Wnt signalling pathways with bone phenotypes and stress fracture injury susceptibility highlights their role in the maintenance of bone health, and offers potential targets for therapeutic interventions.

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11

Svensson, Michael B. "Endogenous antioxidants in human skeletal muscle and adaptation in energy metabolism : with reference to exercise-training, exercise-related factors and nutrition /". Stockholm, 2003. http://diss.kib.ki.se/2003/91-7349-433-X.

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12

Player, Darren James. "An in vitro model for assessment of skeletal muscle adaptation following exercise related physiological cues". Thesis, University of Bedfordshire, 2013. http://hdl.handle.net/10547/311732.

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The aim of this Thesis was to further characterise and utilise an in vitro skeletal muscle (SkM) model, to investigate its potential use in further understanding the cellular and molecular adaptations to exercise in vivo. Candidate genes and proteins have been identified using in vivo, ex vivo and targeted in vitro experiments, however the complete picture of these molecular mechanisms are far from understood. Furthermore, the extent to which mechanical signals contribute to the intra-cellular mechanisms associated with exercise is also underinvesitgated. To this end, developing an in vitro model of SkM that can recapitulate in vivo SkM and respond to mechanical stimulation in a similar way to exercise will provide a means to begin to delineate the complex cellular and molecular regulation of SkM. The initial investigation (Chapter 3) characterised an optimal seeding density and culture period of C2C12 myoblasts within a 3 ml collagen gel. These data provided support for the use of collagen constructs seeded at 4 x 106 cells/ml, with no statistical differences observed in peak force, rate of force development and relative force compared to other seeding densities examined (table 3-2, all p > 0.05). However the use of 4 x 106 cells/ml supports previous data in a larger construct volume model, whilst the highest cell density possible in the system increases cell-cell contact required for fusion. Immunohistochemical and gene expression analyses provided evidence for the fusion of single seeded myoblasts into multinucleate myotubes, demonstrating an in vivo-like architecture. Chapter 4 presented data towards the characterisation and use of two distinct cyclical stretch regimens with respect to the acute biochemical and transcriptional responses. Data revealed increases in peak media lactate and reductions in peak media glucose, following cyclical stetch compared to control (p = 0.000 and p = 0.001 respectively, Fig. 4-2). Changes in mtDNA (Fig. 4-5) and associated mRNA transcriptional signals (Fig. 4-7) were mode dependent.

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13

Rodden, Gregory Robert. "The Effects of Resistance Wheel Running on Skeletal Muscle Function and Adaptation in C57BL/10SnJ Mice". Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/74274.

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Background: Resistance wheel running (RWR) can promote resistance-like training adaptations in mouse skeletal muscle (SkM), but its endurance-training effects are lesser known. Methods: Voluntary RWR was modulated as an exercise model to increase mouse hind-limb plantar-flexor torque and to promote endurance-training adaptations. Thirty male mice (cohort 1, n= 16; cohort 2, n= 14), were trained on a prototype RWR system that applied resistance relative to body mass (BM). Mice were sequentially, (1) screened for running ability (screening; 3-days); (2) trained with incremental adjustments to wheel loads (pre-training; 8-weeks); (3) grouped into cage-activity only (CA), and constant Low-0%, Med-15%, or High-25% BM resistance conditions (static training; 5-weeks); (4) trained with resistance adjusted in real-time (dynamic training; cohort 1, 7-weeks; cohort 2, 10-weeks); and (5) sacrificed for various assays. Plantar-flexor torque was determined during each training phase. After dynamic training, resistance runners in each cohort were sub-grouped post-hoc by work tertiles. Results: Wheel running distance varied between cohorts (cohort 2 > 1). During dynamic training, wheel running (±added-resistance) improved plantar flexor torque normalized to BM by 19% only in cohort 2 (p= 0.007). Muscle mass and cross-sectional area were unchanged. Runners in both cohorts (±added-resistance) improved maximal running capacity vs. CA-controls (+69% and +115%; both p < 0.05), but metabolic training adaptations were less evident. Conclusions: Wheel running promoted SkM strength and endurance, but there was a greater increase in endurance capacity than strength. This outcome may be due to adaptive signaling interference.
Master of Science

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14

Raue, Ulrika. "Effects of concentric vs eccentric resistance training on skeletal muscle adaptations in humans". Virtual Press, 2001. http://liblink.bsu.edu/uhtbin/catkey/1221284.

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The Beothuk Indians were an extinct group of Amerinds who were among the earliest founders of Newfoundland. In literature, the Beothuk were described as perhaps being phenotypically more similar to Europeans than Asians (Gatschet 1890, Lloyd 1875, 1876a, Marshall 1996). In this research, mitochondrial DNA (mtDNA) analysis was performed on a Beothuk individual in order to determine his haplotype and, perhaps, shed light on the origins of the Beothuk.For this analysis, a tooth of Nonosabasut, a Beothuk chief who died in 1819 was loaned from the Royal Museum of Scotland. Ancient DNA was extracted from 172 mg of dentin from the tooth. The DNA was cut with two blunt-end restriction enzymes, RsaI and HaeIII. Double-stranded DNA adapters were ligated to the blunt ends. A single adapter was used to amplify the resulting fragments using PCR. In this manner, two libraries of the DNA were created that could be readily reamplified using a small amount of the PCR product. mtDNA type was determined by amplifying specific regions and performing Restriction Fragment Length Polymorphism analysis and sequencing. It was determined that the Beothuk individual had a 9-bp deletion at nucleotide position (np) 8272, an Alul restriction site at np 5176, and heteroplasmy for a HincII restriction site at np 13,259, indicating that the Beothuk individual falls into the Native American Haplogroup B. Haplogroup B is not present in modern Siberian populations, whereas the remaining Native American mtDNA haplogroups are. It has been hypothesized that Haplogroup B arrived in the Americas at a different time than haplogroups A, C, D, and X, about 16,000-13,000 YBP (Years Before Present) (Starikovskaya et al. 1998). Haplogroup B can be found in some modern Taiwanese, Japanese, Korean, Evenk, and other Asian populations.Sequencing of the D-Loop region revealed a G to A transition at np 16303. To our knowledge, this transition was never previously reported in a Native American. This transition has been reported in Tibetans, Koreans, Hans, and Japanese, all considered to be southeast Asian Causacoids (Torroni et al. 1993b, 1994b). This transition, also frequently described in the Caucasian Haplogroup H, is especially prevalent in Spain and among the Basque. It is described as a root haplotype of Haplogroup H whose expansion was estimated to be between 12,300-13,200 YBP (Torroni et al. 1998). This time estimate coincides with the expansion of Haplogroup B. One possible explanation for this transition may be some admixture of the Beothuk with a Caucasian population.
School of Physical Education

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15

English, Tamara Erica Carleton University Dissertation Biology. "Enzymes of adenylate metabolism from the skeletal muscle of the hibernating prairie dog, Cynomys leucurus". Ottawa, 1995.

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16

Shields, Brenda Czerwinski. "Adaptive response of Japanese quail (Coturnix coturnix japonica) to cold-acclimation physiological changes and localization of avian UCP in skeletal muscle /". Click here for download, 2008. http://proquest.umi.com/pqdweb?did=1564023381&sid=1&Fmt=2&clientId=3260&RQT=309&VName=PQD.

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17

Luitingh, Taryn Leigh. "Adaptation of the microbial decomposer community to the burial of skeletal muscle tissue in contrasting soils". University of Western Australia. Centre for Forensic Science, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0037.

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Microorganisms are known to be agents involved in the decomposition of organic matter. However, little is known about the participation of the microbial communities during the decomposition of mammalian skeletal muscle tissue. This study investigates the capacity of the soil microbial community to adapt to the decomposition of skeletal muscle tissue in differing soils. This has implications for the study of mass graves and sites of repeated burial. A controlled laboratory experiment was designed to assess the adaptability of microbial communities present in three distinct soil types (sand, loamy sand and sandy clay loam) found near Perth, Western Australia. This experiment was split into two main stages. The initial decomposition stage involved the addition of porcine skeletal muscle tissue (SMT) (Sus scrofa) to each of the three soil types which were then left to decompose for a period of time. Controls were run in parallel, which had no porcine SMT present. The second decomposition stage involved a second addition of SMT to the soils obtained from the initial decomposition stage. Therefore, for each soil, SMT was either decomposed in the soil that had been pre-exposed to SMT or not. The rate of decomposition, microbial activity (CO2 respiration) and microbial biomass (substrate-induced respiration) were monitored during the second decomposition stage. The functional diversity of the microbial populations in the soil were assessed using Community-Level Physiological Profiling (CLPP). Across the three soil types, the re-introduction of SMT to the soil has led to its enhanced decomposition (measured by tissue mass loss and microbial activity) by the microbial communities. This microbial adaptation may have been facilitated by a functional change in the soil microbial communities.

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18

Davidsen, Peter Kåre. "Understanding skeletal muscle adaptation in health and chronic disease : a multi-omics based systems biology perspective". Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6563/.

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Mammalian skeletal muscle has a major impact on whole-body metabolic homeostasis. Hence, maintenance of a metabolically active muscle mass is key for optimal health. Notably, both muscle function and mass are profoundly negatively affected by environmental factors such as chronic smoking and physical inactivity. RNA abundance integrates genetic, epigenetic and environmental influences. Therefore, while true understanding of physiological adaptation likely require the integration between multi-level datasets, the transcriptome represents a powerful investigative tool in determining the underlying molecular mechanisms behind complex phenotypic traits. The overarching aim of this thesis was to evaluate, using omics-based systems biology approaches, the global regulation of RNAs during exogenous modulation of mammalian muscle phenotype in order to characterize local homeostatic processes as well as identify robust biomarker signatures. The first part of this thesis deals with smoke-induced peripheral muscle wasting. Initially, biological domain knowledge is used to validate a pre-clinical smoking model. Then, specific cytokines are statistically linked to limb muscle energy metabolism; a testable hypothesis supported by both animal and human data. The second part deals with the development of ‘molecular predictors’ of endurance training adaptability. Two complex clinically relevant traits are considered, namely whole-body insulin sensitivity and plasma triglyceride content. Promisingly, quantitative multi-gene predictors of response to training for both traits of interest were developed.

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19

Sorensen, Jacob R. "Repair and Adaptation of Aged Skeletal Muscle to Nonpathological Muscle Damage: The Influence of Macrophage Polarization". BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/7691.

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The age-related loss of skeletal muscle mass and function is accompanied by a decline in regenerative capacity. The processes that facilitate healthy muscle repair are complex, involving several phases of degradation and rebuilding of muscle tissue and the surrounding microenvironment. Specifically, myogenic progenitor cells known as satellite cells are the most influential in repairing damaged muscle tissue. Following injury, satellite cells become activated and migrate, proliferate and fuse with mature skeletal muscle fibers to restore homeostasis to the tissue. However, satellite cells do not act in isolation, a robust inflammatory response is necessary to facilitate successful and rapid healing. Macrophages are one of the first and most abundant immune cells to infiltrate damaged skeletal muscle tissue. Primarily, macrophages adapt to a proinflammatory state to clear the area of cellular debris, promote degradation of the extracellular matrix and stimulate satellite cell activation and proliferation. Afterwards, a timely transition to an anti-inflammatory state directs rebuilding of the extracellular matrix and terminal differentiation of satellite cells. Indeed, the inhibition of macrophage activity leads to impaired healing and loss of skeletal muscle function. Little is known regarding the behavior of macrophages in aged skeletal muscle following injury in humans. Thus, the objective of this dissertation is to investigate the age-related response of macrophages in human skeletal muscle, and their role in muscle repair.

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20

Siew, Yun Ysi. "The impacts of climate and the environment on human skeletal morphology during the Holocene in north China". Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/267070.

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This dissertation investigates the temporal and regional variation in human skeletal morphology in relation to climate and the environment in Holocene China. Linking skeletal morphology to the changes in climate, subsistence strategy and socio-political development has been well-documented in various geographical areas. Although a general pattern has been observed among different populations, it is evident that local factors have played an equally important role in human morphological variation. China was chosen in this dissertation because its diverse geographical, historical and cultural background provides an ideal setting in which to elucidate human biological responses to a variety different external forces and stimuli. A total sample of 533 adult skeletons, spanning from the mid-Neolithic to the twentieth century, was examined. These skeletons represent the ancient agriculturalists, nomadic pastoralists and agropastoralists inhabiting in contemporary Northeast China and modern humans from South China. This dissertation uses body size and shape, entheseal expression and biomechanical properties of long bones to investigate: 1.) temporal patterns in postcranial dimensions, stature and body mass; 2.) regional differences between the northern and southern Chinese in body size and body/limb proportions; and 3.) variation in skeletal biomechanics and entheses in relation to subsistence strategy. The findings in this dissertation indicated that while the human skeletons studied were morphologically varied throughout Holocene China, they were, to some extent, correlated with climatic and environmental factors. Body size and shape and body/limb proportions corresponded with variation in temperature. Additionally, stature, body mass and entheseal expression were correlated with socio-political and cultural development. Nevertheless, entheseal expression unexpectedly did not show a straightforward relationship with subsistence strategy, in which is inconsistent with the findings of previous studies. Although the comparisons of biomechanical properties were not unequivocal, they suggest differences in mobility and mechanical loading between different populations and subsistence strategies. On the whole, the results suggested that variation in skeletal morphology of the Holocene Chinese follows the universal patterns on the one hand, while on the other, they were influenced by local environmental and behavioural factors.

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Harvey, Mordecai Micah. "Characterization of an in vitro exercise model and the effects of a metabolic endotoxemia on skeletal muscle adaptation to electric pulse stimulation". Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/78235.

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The prevalence of obesity and type II diabetes is increasing. Although exercise is widely accepted for prevention and treatment, evidence of resistance to exercise in patients with these diseases is also mounting. Muscle contraction during exercise stimulate cellular responses important for adaptation. These responses include the release of myokines and the subsequent increase in substrate metabolism. This study aimed to define a culture model for simulating exercise in human primary skeletal muscle cells. We hypothesized that chronic electric pulse stimulation (EPS) of human myotubes in vitro would emulate cellular and molecular responses to exercise observed in vivo. To define this model, we applied EPS to human myotubes for varied lengths of time and measured interleukin-6 (Il-6), peroxisome proliferator-activated receptor gamma coactivator 1- (PGC1-), superoxide dismutase 2 (SOD2), substrate metabolism, metabolic enzyme activity, heat stress markers, and pH. To recreate the inflammatory milieu observed in metabolic disease states we treated the myotubes with a low dose of 20 EU lipopolysaccharide (LPS). Following the 24-hour stimulation we observed significant increases in transcription of Il-6, PGC1-, and SOD2. Basal glucose and fatty acid oxidation were also markedly increased in the cells after EPS. Cells treated with LPS elicited a blunted transcriptional, metabolic, and enzymatic response to EPS. These findings suggest that EPS is a viable model for simulating the effects of exercise. Our observations also indicate that an inflammatory environment could play a role in interfering with the adaptations to exercise.
Ph. D.

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22

Ali, Mostafa M. "The Role of Toll Like Receptor-4 in Exercise-induced Myokine Response and Regulation of Skeletal Muscle Metabolic Adaptation". Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/84870.

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Toll like receptor-4 (TLR4) is a transmembrane inflammatory receptor expressed ubiquitously on the cell surface of immune cells as well as skeletal muscle and other metabolic tissues. A compelling body of evidence shows that muscle TLR4 and the downstream cytokine signaling modulate skeletal muscle metabolism. Intriguingly, skeletal muscle has been demonstrated to gain favorable inflammatory cytokine-mediated metabolic adaptations in the context of exercise training. This paradigm suggests a role for muscle TLR4 inflammatory signaling in the regulation of exercise metabolism. As such, the question arises as to whether exercise stress response follows similar inflammatory physiological pathways to those activated by other physical and pathogenic stimuli or not. Therefore, the objective of the present study was to investigate the role of muscle TLR4 signaling in modulating skeletal muscle cytokine, also known as myokine, response and metabolic adaptations to exercise. To this end, using Cre-mediated recombination, we developed a novel muscle-specific TLR4 knockout (mTLR4-/-) mouse model on C57BL/6JJ background. The differential inflammatory and metabolic responses between mTLR4-/- mice and wild type (WT) littermates were examined following exposure to either exercise or muscle stimulus. Accordingly, different exercise and muscle contraction modalities were pursued, focusing on voluntary wheel running, forced treadmill training, and in vivo electrical muscle stimulation. Overall, this study introduces a novel muscle-specific TLR4 knockout mouse model and discloses a crucial role for mTLR4 in basal systemic cytokine homeostasis. Furthermore, our findings identify mTLR4 as a major immunomodulatory effector of exercise-induced metabolic adaptations and suggest a link between mTLR4 and physiological determinants of maximal aerobic performance.
Ph. D.

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23

Zheng, Wenya [Verfasser]. "Impacts of isoflavones and physical activity on skeletal muscle anabolic adaptation and fatty acid metabolism / Wenya Zheng". Köln : Zentralbibliothek der Deutschen Sporthochschule, 2017. http://d-nb.info/1151513717/34.

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24

Yu, Fushun. "Adaptability of skeletal muscle to hormone treatment in relation to gender and aging /". Stockholm, 1999. http://diss.kib.ki.se/1999/91-628-3585-8/.

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25

Swisher, Anne K. "The effect of emphysema on adaptation of peripheral skeletal muscle to different loading conditions in the Syrian golden hamster". Morgantown, W. Va. : [West Virginia University Libraries], 2003. http://etd.wvu.edu/templates/showETD.cfm?recnum=3008.

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Thesis (Ph. D.)--West Virginia University, 2003.
Title from document title page. Document formatted into pages; contains vii, 141 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.

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Januševičius, Donatas. "Skirtingos griaučių raumenų adaptacijos įtaka galingumui". Master's thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2013~D_20130910_154834-73898.

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Galingumas yra ryšys tarp jėgos ir greičio. Galingumo ugdymo pratimai skirti skatinti neuroraumenų sistemą, kad per trumpą laiko tarpą raumuo spėtų išsitempti (ekscentrinis susitraukimas) ir susitraukti (koncentrinis susitraukimas) (Foran, Pound, 2007). Galingumui reikalinga maksimalioji jėga ir didelis judesio greitis (Табачник, 1988; Matthew et al., 2011). Wilson G.J. su bendraautoriais (1993) nustatė, kad galingumas po jėgos treniruočių pagerėjo 5 %; po pliometrijos treniruočių – 10 %; po balistinių (greitumo jėgos) pratimų – 18 %. Tiriant tokias sporto šakas kaip krepšinis ir tinklinis buvo pastebėtos svarbios sąsajos tarp didžiausios jėgos ir didžiausio galingumo (Peterson et al., 2006). Vyksta dideli ginčai dėl to, kuri iš šių savybių turėtų būti svarbiausia treniruočių metu, siekiant išvystyti didžiausią galingumą (Haff et al., 2012). Darbo objektas - skirtingos griaučių raumenų adaptacijos įtaka galingumui. Keliame hipotezę, kad adaptuoti jėgos fiziniams krūviams tiriamieji greičiau bėgs 30 m distancijos pradžią, o adaptuoti maksimaliajam bėgimo greičiui – greičiau bėgs nuotolio pabaigoje. Tikslas — nustatyti skirtingos griaučių raumenų adaptacijos įtaką galingumui. Uždaviniai: 1. Nustatyti skirtingos griaučių raumenų adaptacijos įtaką maksimaliai valingai kojų raumenų, santykinei jėgai bei greitumui. 2. Nustatyti 30 m bėgimo rezultatus, 10 m bėgimo atkarpose, priklausomai nuo griaučių raumenų adaptacijos skirtingoms fizinėms ypatybėms. Tyrimo metodai: 1)... [toliau žr. visą tekstą]
Power is the relationship between force and velocity. Power exercise are made to promote neuromuscular system in a short period of time to make a meaningful muscle stretch (eccentric contraction), and to contract (concentric contraction) (Foran, Pound, 2007). Maximal strength and high speed of motion are necessary for peak power (Tabačnik, 1988; Matthew et al., 2011). Wilson G.J. with co-authors (1993) found the improvement of power after strength training - 5%, after plyometric training - 10%, and after balistic (speed - strength) training - 18%. Investigating such sports as basketball and volleyball it was observed significant correlation between the maximum force and maximum power evelopment (Peterson et al., 2006). There are undergoing some controversy research as to which of these properties should be the most important during training to develop maximum power (Haff et al., 2012). The object of the study - the influence of different skeletal muscle adaptations on muscular power. Hypothesis: subjects having a larger MVC will run faster 30 m distance field, and having a higher maximal running speed - will run faster at the end of range. The aim of this study: to determine the influence of different skeletal muscle adaptations on muscular power. Objectives: 1. To determine the influence of different skeletal muscle adaptations on maximum voluntary strength of leg muscles, the relative strength and quickness. 2. To determine the influence of different skeletal muscle... [to full text]

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Alligood, Kristin. "Using Natural Populations of Threespine Stickleback to Identify the Genomic Basis of Skeletal Variation". Thesis, University of Oregon, 2017. http://hdl.handle.net/1794/22781.

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Across vertebrates, skeletal shapes are diverse, and much of this variation appears to be adaptive. In contrast, the early developmental programs of these structures are highly conserved across vertebrates. The question then becomes where in the conserved genetic programs of skeletal development does variation lie to direct diversity? In threespine stickleback, rapid changes in head and body shape have been documented during repeated and independent invasions of oceanic fish into freshwater habitats in regions deglaciated approximately 13,000 years ago. However, recent research indicates that similar phenotypic and genetic divergence can occur in decades. A remaining challenge is to link stickleback population genomic variation to causal genes that underlie such rapid phenotypic evolution. Here I use genome wide association studies (GWAS) in natural populations of stickleback to uncover genomic regions that contribute to variation of two dermal bone derived traits, lateral plate number and opercle shape. The decrease of lateral plate body armor and change in opercle bone shape, important for feeding mechanics, are classically associated with freshwater divergence. GWAS has recently begun to be used in natural populations but is still under scrutiny for performance among different populations. Using a population of phenotypically variable stickleback in Oregon, GWAS proved an effective method to uncover genomic regions and genetic variants known to contribute to lateral plate number and opercle shape, as well as new genomic regions and candidate genes not previously implicated in phenotypic variation. Although successful, using similar methods on decades old stickleback populations in Alaska revealed the challenges that accompany controlling population structure created by strong natural selection. Together, I found that although lateral plate number and opercle shape rapidly evolve in a coordinated fashion during adaptation from marine to freshwater environments, phenotypic variation is largely driven by independent genetic architectures. However, in very rapidly evolving populations, despite this independence of genetic architecture, the genetic variants contributing to the traits co-localize to similar genomic regions. This finding could be either biological or methodological which highlights the promise and limitations of using GWAS to identify genetic variation that gives rise to phenotypic diversity. This dissertation includes unpublished co-authored material.

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Myllymäki, M. (Mikko). "Hypoxia-inducible factor prolyl 4-hydroxylase-2 in Tibetan high-altitude adaptation, extramedullary erythropoiesis and skeletal muscle ischemia". Doctoral thesis, Oulun yliopisto, 2016. http://urn.fi/urn:isbn:9789526212210.

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Abstract Adequate oxygen supply is necessary for aerobic cell survival. Cellular oxygen deprivation, also known as hypoxia, leads to various responses that aim to increase cellular oxygen delivery and reduce oxygen consumption. Oxygen homeostasis is mainly regulated by the hypoxia-inducible factor (HIF), which regulates the expression of over 300 genes in response to hypoxia. The stability of HIF is regulated by the HIF prolyl 4-hydroxylases (HIF-P4Hs), enzymes that catalyze the hydroxylation of proline residues in HIFα subunits and target them towards proteasomal degradation. HIF-P4Hs require oxygen as a cosubstrate for the reaction, allowing for hypoxic HIF stabilization and target gene induction at low oxygen concentrations. In this study we investigated the role of HIF-P4H-2 in the regulation of red blood cell production, erythropoiesis. We showed that Tibetans living at high altitude have genetically adapted to their hypoxic environment via mutations in the gene encoding for HIF-P4H-2. The Tibetan HIF-P4H-2 D4E,C127S variant showed enhanced hydroxylation of HIFα at low oxygen concentrations, resulting in reduced HIFα protein stabilization under hypoxia. In other studies we used a genetically modified HIF-P4H-2 hypomorphic mouse line which expresses a reduced amount of wild-type Hif-p4h-2 mRNA in tissues. We showed that these mice develop mild age-dependent erythrocytosis due to splenic extramedullary erythropoiesis, which is independent of serum erythropoietin concentration. In addition, these mice were protected against inflammation-induced anemia, a condition commonly seen in patients with inflammatory diseases. The HIF-P4H-2 hypomorphic mice also had altered basal metabolism in their skeletal muscles, which, together with an increase in mean capillary area, reduced their infarct size after skeletal muscle ischemia-reperfusion injury. These studies suggest that pharmacological HIF-P4H-2 inhibition may provide a novel treatment for EPO-resistant anemias and peripheral artery disease
Tiivistelmä Riittävä hapensaanti on välttämätöntä aerobisten solujen selviytymiselle. Solun alentunut hapen määrä, toiselta nimeltään hypoksia, johtaa useisiin vasteisiin joiden tarkoituksena on turvata solun hapensaanti ja vähentää hapenkulutusta. Happitasapainoa säätelee hypoksiassa indusoituva tekijä (HIF), joka aktivoi yli 300 geenin luentaa hypoksisissa oloissa. HIFα:n määrää soluissa säätelevät HIF prolyyli-4-hydroksylaasientsyymit (HIF-P4H:t), jotka hydroksyloivat proliini-aminohappotähteitä HIFα-alayksiköissä ja ohjaavat ne proteasomaaliseen hajotukseen. HIF-P4H:t tarvitsevat reaktiossa happea mahdollistaen HIF:n stabilisaation ja kohdegeenien lisääntyneen luennan matalassa hapen osapaineessa. Tässä tutkimuksessa selvitimme HIF-P4H-2-entsyymin roolia punasolujen muodostuksen eli erytropoieesin säätelyssä. Osoitimme, että korkealla vuoristossa asuvat tiibetiläiset ovat geneettisesti sopeutuneet hypoksiseen elinympäristöönsä johtuen HIF-P4H-2-entsyymiä tuottavan geenin mutaatiosta. Tiibetiläisiltä löytynyt HIF-P4H-2D4E,C127S variantti hydroksyloi tehokkaammin HIFα-alayksiköitä matalassa hapen osapaineessa johtaen vähäisempään HIFα-alayksiköiden stabiloitumiseen hypoksiassa. Muissa tutkimuksissamme käytimme geneettisesti muunneltua HIF-P4H-2-hiirikantaa, joka tuottaa alentunutta määrää villityypin Hif-p4h-2 lähetti-RNA:ta kudoksissaan. Näille hiirille kehittyi ikäriippuvaisesti lievä punasoluylimäärä eli erytrosytoosi johtuen pernan kiihtyneestä punasolutuotannosta riippumatta seerumin erytropoietiinikonsentraatiosta. Lisäksi nämä hiiret olivat suojassa tulehduksen aiheuttamalta anemialta, joka on yleinen ilmiö tulehduksellisista sairauksista kärsivillä potilailla. HIF-P4H-2-muuntogeenisten hiirten lihasten energia-aineenvaihdunta oli muuttunut siten, että se yhdessä suurentuneen keskimääräisen kapillaaripinta-alan kanssa pienensi vaurioituneen kudoksen pinta-alaa alaraajaiskemia-altistuksen jälkeen. Nämä tutkimukset osoittavat, että lääkkeellinen HIF-P4H-2-entsyymin estäminen on mahdollinen uusi hoitomuoto erytropoietiinille resistenteissä anemioissa sekä alaraajojen valtimoahtaumataudissa

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Norrbrand, Lena. "Acute and early chronic responses to resistance exercise using flywheel or weights". Stockholm : Department of Physiology and Pharmacology, Karolinska Institutet, 2008. http://diss.kib.ki.se/2008/978-91-7409-030-7/.

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Masuda, Shinya. "Adaptation of cytoskeletal and sarcolemmal proteins for functional requirements － new information for the development of fatigue resistance in skeletal muscle －". Kyoto University, 2009. http://hdl.handle.net/2433/123932.

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Abstract (sommario):

Kyoto University (京都大学)
0048
新制・課程博士
博士(人間・環境学)
甲第14717号
人博第453号
新制||人||111(附属図書館)
20||人博||453(吉田南総合図書館)
UT51-2009-D429
京都大学大学院人間・環境学研究科共生人間学専攻
(主査)准教授林達也, 教授森谷敏夫, 教授小田伸午, 教授田口貞善
学位規則第4条第1項該当

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31

Terpstra, Brian T. "Age and gender related differences in skeletal muscle adaptations to twelve weeks of progressive resistance training". Virtual Press, 2001. http://liblink.bsu.edu/uhtbin/catkey/1217387.

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Diabetic patients are prone to complications and need foot care education. The purposes of this study were to (1) examine the effectiveness of instruction on knowledge of foot care in diabetics, and practice of foot care in diabetics, and (2) examine the relationship between health promoting behaviors and foot care practices. The theoretical framework for this study was Nola Pender's Health Promotion Model. The sample for the study consisted of 69 individuals, ages 18 and older with diabetes mellitus (Type I or Type II).Control and experimental groups completed a demographic sheet and Pender's Health Promoting Lifestyle Profile. The control group received the traditional intervention of a written handout (Novo Nordisk Pharmaceuticals, Inc.) and a packet including an emery board, moisturizing lotion, and a hand-held mirror. The experimental group received a specialized nursing intervention of one-on-one instruction along with a written handout, and a packet including an emery board, moisturizing lotion, and a handheld mirror. Both groups were informed of a $10.00 stipend obtainable and paid by the researcher, for those who completed the study. Two weeks following the office visit, both groups received by mail: a follow-up letter, post-tests on knowledge (Knowledge Questionnaire) and practice (Practice Profile), and a stamped return envelope.There was a significant difference between the control group and the experimental group in knowledge of foot care. There was no significant difference between the control group and the experimental group in practices of foot care. There was a significant, positive correlation (r=.306, p=.012) between the practices of health promoting behaviors and foot care practices. Also, educational level was positively correlated (r=.432, p=.001) with knowledge of foot care.Several studies have been done on diabetic foot care instruction but few have been done to compare different methods of instruction with foot care knowledge and practice. One-on-one education provides an opportunity for the learner to play an active role in the discussion of alternative methods of foot care while allowing for immediate feedback from the nurse educator. Packets that include a well-written instruction sheet and foot care items for patient use can be helpful when educating patients about foot care.
School of Physical Education

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32

Ferrari, Andrea Lepos. "Adaptação transcultural do questionário \"cultural study of musculo-skeletal and other symptoms and associated disability\" CUPID Questionnaire". Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/7/7131/tde-07072009-094358/.

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Este estudo objetivou a adaptação transcultural do questionário Cultural Study of Musculo-Skeletal and Other Symptoms and Associated Disability - CUPID Questionnaire, para a língua portuguesa falada no Brasil e a validação do seu conteúdo. O estudo é do tipo metodológico e foi realizado obedecendo aos procedimentos internacionais recomendados e aos procedimentos específicos indicados pelo autor do Questionário, uma vez que será aplicado em estudo multicêntrico por ele coordenado. A adaptação transcultural foi realizada seguindo as etapas de tradução, retrotradução, avaliação destas versões por um comitê de juízes e pré-teste da versão pré-final. O pré-teste foi realizado no Departamento de Enfermagem do Hospital Universitário da Universidade de São Paulo com 40 trabalhadores de enfermagem. Ajustes foram feitos após a análise das traduções pelo comitê de juízes quando o Índice de Validade de Conteúdo foi inferior a 80%. A versão resultante do questionário foi então pré-testada para verificar a capacidade compreensão e preenchimento pelos sujeitos e a possibilidade de ajustes, considerando o indicativo de ajustes quando 15% destes apresentassem dificuldades em relação ao preenchimento. Os resultados do pré-teste apontam um número significativo de trabalhadores de enfermagem com dores em região lombar, ombro, cotovelo, punho e/ou mão e joelho, associados a sintomas psicossociais e demais incapacidades. A análise das respostas dos sujeitos aos itens do Questionário não evidenciou dificuldades de compreensão e entendimento na totalidade dos itens, indicando a validade de seu conteúdo para a língua portuguesa falada no Brasil. Conclui-se que a versão Brasileira do CUPID Questionnaire é um instrumento adequado para identificar os sintomas musculoesqueléticos, indicados pelos trabalhadores de enfermagem, relacionados às atividades ocupacionais, aspectos psicossociais e outras incapacidades associadas
The objective of this study was to adapt the Transcultural Questionnaire Cultural Study of Muscular-Skeletal and Other Symptoms and Associated Disability CUPID Questionnaire, to the Portuguese language spoken in Brazil and to validate its contents. This methodological study was performed in accordance with internationally recommended procedures and the specific procedures indicated by the Questionnaires author since it will be applied in a multicenter study coordinated by the author. The transcultural adaptation was performed following the steps of translation, back-translation, evaluation of these versions by a committee of judges and pre-test version of the pre-final. The pre-test was performed in the Nursing Department of University Hospital at the University of Sao Paulo with 40 nursing workers. Adjustments were made after an analysis of the translations by a committee of judges when an index of content validation was less than 80%. The resulting version of the questionnaire was then pre-tested to verify the capacity of comprehension and form completion by the subjects and the possibility of adjustments considering an adjustment indicator when 15% of them presented difficulty related to form completion. The results of this pre-test showed that a significant number of Nursing workers complained of pain in the regions of lumbar, shoulder, elbow, wrist and or hand and knee, symptoms associated with psychosocial and other disabilities. Analysis of the subjects responses to items of the questionnaire revealed no difficulty in the comprehension and total understanding of the items indicating a validity of its contents for the Portuguese language spoken in Brazil. It can be concluded that the Brazilian Version of the CUPID Questionnaire is an adequate instrument for the identification of musculoskeletal symptoms indicated by nursing workers related to occupational activities, psychosocial aspects and other associated incapacities

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33

Feldman, Chris R. "Evolutionary Genetics of Tetrodotoxin (TTX) Resistance in Snakes: Tracking a Feeding Adaptation from Populations Through Clades". DigitalCommons@USU, 2008. https://digitalcommons.usu.edu/etd/159.

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Understanding the nature of adaptive evolution has been the recent focus of research detailing the genetic basis of adaptation and theoretical work describing the mechanics of adaptive evolution. Nevertheless, key questions regarding the process of adaptive evolution remain. Ultimately, a detailed description of the ecological context, evolutionary history, and genetic basis of adaptations is required to advance our understanding of adaptive evolution. To address some of the contemporary issues surrounding adaptive evolution, I examine phenotypic and genotypic changes in a snake feeding adaptation. Adaptations can arise through fixation of novel mutations or recruitment of existing variation. Some populations of the garter snakes Thamnophis sirtalis, T. couchii, and T. atratus possess elevated resistance to tetrodotoxin (TTX), the lethal toxin of their newt prey. I show that TTX resistance has evolved independently through amino acid changes at critical sites in a voltage-gated sodium channel protein (Nav1.4) targeted by TTX. Thus, adaptive evolution has occurred multiple times in garter snakes via de novo acquisition of beneficial mutations. Detailing the genetic basis of adaptive variation in natural populations is the first step towards understanding the tempo and mode of adaptive evolution. I evaluate the contribution of Nav1.4 alleles to TTX resistance in two garter snake species from central coastal California. Allelic variation in Nav1.4 explains 29% and 98% of the variation in TTX resistance in T. atratus and T. sirtalis, respectively, demonstrating that Nav1.4 is a major effect locus. The simple genetic architecture of TTX resistance in garter snakes may significantly impact the dynamics of trait change and coevolution. Patterns of convergent evolution are cited as some of the most compelling examples of the strength of natural selection in shaping organismal diversity. Yet repeated patterns may tell us as much about the constraints that restrict evolution as about the importance of natural selection. I present data on convergent molecular adaptations in parallel arms races between diverse snakes and amphibians from across the globe. Six snake species that prey on TTX bearing amphibians have independently acquired amino acid changes in Nav1.4. The derived mutations are clustered in two portions of the gene, often involving the same sites and substitutions. While a number of amino acid changes can make Nav1.4 insensitive to TTX, most of these negatively impact or abolish the ion-conducting function of the protein. Thus, intramolecular pleiotropy likely prevents most replacements from becoming fixed and imposes limits on protein evolution.

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34

Caldas, de Almeida Araujo Ericky. "Adaptation of Proof of Concepts Into Quantitative NMR Methods : Clinical Application for the Characterization of Alterations Observed in the Skeletal Muscle Tissue in Neuromuscular Disorders". Phd thesis, Université Paris Sud - Paris XI, 2014. http://tel.archives-ouvertes.fr/tel-01067940.

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Abstract (sommario):

Current quantitative nuclear magnetic resonance (NMR) technics offer biomarkers that allow performing non-invasive longitudinal studies for the follow up of therapeutic trials in neuromuscular disorders (NMD). In contrast to fat degeneration, the mechanisms of inflammation/oedema/necrosis and fibrosis are characteristic signs of disease activity, which makes their quantification a promising source of crucial biomarkers for longitudinal studies. This thesis work consisted on the implementation of more precise quantitative NMR methods adapted to the clinical study of skeletal muscle (SKM) for : (i) detection and quantification of sites of disease activity by T2-mapping of muscle water ; (ii) investigation of the different pathophysiological mechanisms underlying T2 alterations ; and (iii) Detection and quantification of muscle fibrosis. We implemented two methods for T2 mapping of muscle water. The first one is based on a multi-spin-echo sequence du type CPMG. In this method the 1H-NMR signals from water and lipids are acquired simultaneously. The acquired data are fitted to a tri-exponential model, in which water and fat signals are separated by exploring the T2 difference between water and fat. This method allows extraction of muscle water T2-value in the presence of fat infiltration. The second method is based on a " partially spoiled steady state free precession " (pSSFP) sequence. In contrast to the first method, which demands a sophisticated post-treatment of images acquired at 17 different echo-times, with the pSSFP a T2-mapping is extracted from two 3D data sets. 3D acquisition is compatible with spectrally selective water excitation, which eliminates signal contribution from lipids. Both methods were validated experimentally on patients and healthy subjects. The results demonstrated their capacity to detect and quantify disease activity sites. This 2 works have been published in two international journals : Azzabou, de Sousa, Araujo, & Carlier, 2014. Journal of Magnetic Resonance Imaging. DOI 10.1002/jmri.24613 (in press); et de Sousa, Vignaud, Araujo, & Carlier . 2012. Magnetic Resonance in Medicine. 67:1379-1390. Although it was shown to reveal disease activity, mono-exponential T2 of muscle water is non-specific to what concerns the mechanisms underlying its alterations. It has been long known that T2 relaxation in SKM tissue is multi-exponential. This is currently accepted to reveal anatomical compartmentation of myowater. We implemented a method for localized spectroscopic CPMG acquisition. CPMG data respect echo-time sampling and signal to noise ration limits for allowing robust multiexponential analysis. This work allowed us to establish a compartmentation model that perfectly explains the multi-exponential T2 relaxation observed in SKM tissue. This work was published in the " Biophysical Journal " (Araujo, Fromes & Carlier 2014. New Insights on skeletal muscle tissue compartments revealed by T2 NMR relaxometry. (In press)). Pilot studies performed in patients show promising results and suggest potential application of the method in clinical studies. Fibrosis starts with an excessive accumulation of intramuscular connective tissue (IMCT). We have explored the " Ultrashort time to echo " (UTE) method with the aim to detect and characterize the signal from IMCT. In a first study we characterized in vivo a short T2 component (~500 µs) in SKM, and we collected evidences suggesting that this component might reflect IMCT. Then we implemented a methodology that allowed imaging this short component in SKM tissue for the first time.

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35

Araujo, Ericky Caldas de Almeida. "Adaptation of Proof of Concepts Into Quantitative NMR Methods : Clinical Application for the Characterization of Alterations Observed in the Skeletal Muscle Tissue in Neuromuscular Disorders". Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112075/document.

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Actuellement, des méthodes quantitatives de résonance magnétique nucléaire (RMN) offrent des biomarqueurs qui permettent la réalisation d’études longitudinales pour le suivi de l’évolution des maladies neuromusculaires et des essais thérapeutiques de manière non-invasive. A la différence de la dégénérescence graisseuse, les processus d’inflammation/œdème/nécrose et fibrose sont des signes d’activité des maladies et leurs quantifications constitueraient ainsi de biomarqueurs parfaitement adaptés pour le suivi thérapeutique. Ce travail de thèse a consisté à mettre en place des méthodologies quantitatives plus précises et adaptées à l’étude clinique du muscle pour : (i) détecter et quantifier des sites d’activité de maladies par la cartographie T2 de l’eau ; (ii) identifier les différents processus pathophysiologiques qui sont à l’origine des altérations du T2 ; et (iii) détecter et quantifier la fibrose musculaire. Nous avons implémenté deux méthodes pour la quantification du T2 de l’eau dans le muscle. La première est basée sur une séquence d’écho de spin du type CPMG, où les signaux provenant des protons des lipides et de l’eau sont acquis simultanément et séparés à postériori par un traitement tri-exponentiel qui exploite la différence entre les T2 qui caractérisent les signaux de l’eau et de la graisse. La deuxième technique est basée sur une séquence de « partially spoiled steady state free precession (pSSFP) ». Différemment de la première technique qui nécessite un traitement assez élaboré sur des images acquises à 17 temps d’écho différents, dans la pSSFP la cartographie T2 est extraite à partir de deux séries de données 3D. L’acquisition 3D est compatible avec des techniques de sélection spectrale de l’eau, ce qui évite la contamination par les signaux des lipides. Les deux méthodes ont été validées expérimentalement chez des malades et des sujets sains et ont démontré leur capacité à détecter et quantifier des sites d’activité de maladies. Ces deux travaux font l’objet de deux publications dans des journaux scientifiques internationaux : Azzabou, de Sousa, Araujo, & Carlier, 2014. Journal of Magnetic Resonance Imaging. DOI 10.1002/jmri.24613 (in press); et de Sousa, Vignaud, Araujo, & Carlier . 2012. Magnetic Resonance in Medicine. 67:1379-1390. Malgré le fait de permettre la détection des sites d’activité de maladies, la mesure mono-exponentielle du T2 de l’eau par imagerie reste non-spécifique vis-à-vis des processus physiologiques à l’origine de l’augmentation du T2. Il est connu que la relaxation T2 du muscle squelettique n’est pas mono-exponentielle. Cela est interprété comme une conséquence de la compartimentation anatomique de l’eau tissulaire. Nous avons mis au point une méthode pour l’acquisition localisée de données CPMG. Cette technique permet l’acquisition des données dans des conditions nécessaires pour la réalisation de traitements multi-exponentiels précis. Ce travail nous a permis d’établir un modèle de compartimentation qui explique parfaitement la relaxation T2 dans le muscle. Il a fait l’objet d’un article publié dans le « Biophysical Journal » (Araujo, Fromes & Carlier 2014. New Insights on skeletal muscle tissue compartments revealed by T2 NMR relaxometry. (In press)). Les essais réalisés chez des sujets malades suggèrent un grand potentiel pour l’application de la méthode dans des études cliniques. La formation de la fibrose commence avec une accumulation excessive de tissu conjonctif intramusculaire (TCIM). Nous avons exploité la technique « Ultrashort Time-to-Echo » (UTE) pour essayer de détecter et caractériser le signal du TCIM. Dans une première étude, nous avons caractérisé in vivo une composante à T2 court (~500 µs) dans le muscle, et nous avons trouvé des indices qui suggèrent qu’elle représente le TCIM. Dans une deuxième étude, nous avons mis au point une méthodologie qui a permis d’imager cette composante à T2 court dans le muscle pour la première fois
Current quantitative nuclear magnetic resonance (NMR) technics offer biomarkers that allow performing non-invasive longitudinal studies for the follow up of therapeutic trials in neuromuscular disorders (NMD). In contrast to fat degeneration, the mechanisms of inflammation/oedema/necrosis and fibrosis are characteristic signs of disease activity, which makes their quantification a promising source of crucial biomarkers for longitudinal studies. This thesis work consisted on the implementation of more precise quantitative NMR methods adapted to the clinical study of skeletal muscle (SKM) for : (i) detection and quantification of sites of disease activity by T2-mapping of muscle water ; (ii) investigation of the different pathophysiological mechanisms underlying T2 alterations ; and (iii) Detection and quantification of muscle fibrosis. We implemented two methods for T2 mapping of muscle water. The first one is based on a multi-spin-echo sequence du type CPMG. In this method the 1H-NMR signals from water and lipids are acquired simultaneously. The acquired data are fitted to a tri-exponential model, in which water and fat signals are separated by exploring the T2 difference between water and fat. This method allows extraction of muscle water T2-value in the presence of fat infiltration. The second method is based on a « partially spoiled steady state free precession » (pSSFP) sequence. In contrast to the first method, which demands a sophisticated post-treatment of images acquired at 17 different echo-times, with the pSSFP a T2-mapping is extracted from two 3D data sets. 3D acquisition is compatible with spectrally selective water excitation, which eliminates signal contribution from lipids. Both methods were validated experimentally on patients and healthy subjects. The results demonstrated their capacity to detect and quantify disease activity sites. This 2 works have been published in two international journals : Azzabou, de Sousa, Araujo, & Carlier, 2014. Journal of Magnetic Resonance Imaging. DOI 10.1002/jmri.24613 (in press); et de Sousa, Vignaud, Araujo, & Carlier . 2012. Magnetic Resonance in Medicine. 67:1379-1390. Although it was shown to reveal disease activity, mono-exponential T2 of muscle water is non-specific to what concerns the mechanisms underlying its alterations. It has been long known that T2 relaxation in SKM tissue is multi-exponential. This is currently accepted to reveal anatomical compartmentation of myowater. We implemented a method for localized spectroscopic CPMG acquisition. CPMG data respect echo-time sampling and signal to noise ration limits for allowing robust multiexponential analysis. This work allowed us to establish a compartmentation model that perfectly explains the multi-exponential T2 relaxation observed in SKM tissue. This work was published in the « Biophysical Journal » (Araujo, Fromes & Carlier 2014. New Insights on skeletal muscle tissue compartments revealed by T2 NMR relaxometry. (In press)). Pilot studies performed in patients show promising results and suggest potential application of the method in clinical studies. Fibrosis starts with an excessive accumulation of intramuscular connective tissue (IMCT). We have explored the « Ultrashort time to echo » (UTE) method with the aim to detect and characterize the signal from IMCT. In a first study we characterized in vivo a short T2 component (~500 µs) in SKM, and we collected evidences suggesting that this component might reflect IMCT. Then we implemented a methodology that allowed imaging this short component in SKM tissue for the first time

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36

Miller, Vincent J. "The effect of a ketogenic diet on mitochondria function in human skeletal muscle during adaptation to chronic exercise training and the potential involvement of metabolic dysregulation". The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1554558461682203.

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37

Ferrucci, Danilo Lopes 1982. "Efeito do exercicio incremental exaustivo nas metaloproteinases 2 e 9 no musculo gastrocnemio de ratos Wistar". [s.n.], 2018. http://repositorio.unicamp.br/jspui/handle/REPOSIP/314734.

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Abstract (sommario):

Orientadores: Denise Vaz de Macedo, Dagmar Ruth Stach-Machado
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-15T21:15:50Z (GMT). No. of bitstreams: 1 Ferrucci_DaniloLopes_M.pdf: 1810214 bytes, checksum: 4728c1ea4c33f76583148c1588199a23 (MD5) Previous issue date: 2018-08-15T18:15:37Z
Resumo: Os músculos esqueléticos são constituídos por fibras musculares e pela matriz extracelular. Em resposta ao exercício, o músculo apresenta a habilidade de transformar o estresse mecânico da contração muscular em adaptações de cunho biológico, a esse processo deu-se o nome de mecanotransdução. Embora pouco se saiba sobre a importância da matriz extracelular como mecanoreceptor, trabalhos anteriores mostram que o exercício pode causar alterações na expressão e atividade das metaloproteinases, que podem resultar em modificações na matriz extracelular. Nesse contexto, as MMPs são vistas como pivôs centrais e, através da degradação da matriz extracelular podem gerar fragmentos protéicos com funções distintas das proteínas integras, liberando ainda citocinas e fatores de crescimento associados à matriz, que em interação com receptores celulares fornecem informações à célula sobre o microambiente extracelular, regulando o comportamento e adaptação do tecido. O objetivo do presente estudo foi avaliar o efeito de três sessões diárias de exercício exaustivo, realizados com diferentes pausas recuperativas entre as sessões, grupo E1(1h) e grupo E2 (3h), durante 6 dias consecutivos, na expressão das MMPs 2 e 9 e dos TIMPs 1 e 2; e nas concentrações e atividade biológica das MMPs nas porções vermelha (GV) e branca (GB) do músculo Gastrocnêmio de ratos Wistar. Os animais foram sacrificados após 1°, 3° e 6° dias de exercício e os fragmentos coletados do músculo gastrocnêmio foram analisados via ELISA, zimografia e qRT-PCR. Como controle (C) do protocolo experimental utilizou-se ratos sedentários. Os animais exercitados (E) mostraram aumento de desempenho a partir do 4° dia. Não houve diferença significativa na perfomance dos grupos E1 e E2. Os genes analisados mostraram-se igualmente expressos em resposta ao exercício em ambas as porções do músculo gastrocnêmio, contudo, o grupo E1 apresentou alterações mais acentuadas do que E2 para todos os biomarcadores analisados. O grupo E1 mostrou aumento na expressão das MMPs 2 e 9 no 3° dia de exercício, em ambas as regiões do músculo gastrocnêmio. Com relação aos TIMPs 1 e 2, os dados obtidos demonstram o aumento na expressão no GV e GB em resposta ao exercício (E1 e E2), em todos os tempos experimentais analisados. Todavia esse aumento foi mais acentuado para o grupo E1. A concentração total de MMP-2 nos grupos e E1 e E2 mostrou-se diminuída em todos os períodos analisados, para GV e GB. A atividade das isoformas latente e intermediária da MMP-2 apresentou-se diminuída em ambos os grupos exercitados no GB e apenas no grupo E1 para o GV. A atividade e concentração da MMP-9 não foram detectadas neste estudo. O protocolo agudo utilizado nesse estudo induziu um aumento significativo no desempenho dos animais, independente do tempo de pausa entre as sessões. O efeito adaptativo observado nas MMPs 2 e 9 em GV e GB foi de diminuição quantitativa e qualitativa. Possivelmente o aumento significativo na expressão gênica tanto das MMPs quanto TIMPs no grupo E1, permitiu um remodelamento acelerado na matriz extracelular do tecido, que possibilitou a melhora significativa no desempenho a partir do 3° dia. Considerando que ambos os tempo de pausa foram igualmente eficientes para aumentar a performance, seria melhor utilizar uma pausa de 3h entre as sessões, pois o processo de sinalização de síntese protéica demanda grande quantidade de energia, e depende da oferta de nutrientes em quantidade e qualidade adequada para a resposta
Abstract: Skeletal muscles are composed by muscle fibers and extracellular matrix. In response to exercise, muscles have the ability to transform mechanical stress from their contraction in biological adaptations, and, this process was called echanotransduction. Although little is known about the importance of the extracellular matrix acting as mechanoreceptors in this process, previous studies have shown that exercise can cause changes in the MMPs genetic expression and activity on the extracellular matrix. In this context, MMPs play the central role, once that the extracellular matrix degradation can generate fragments that are bioactive compounds and can interact with cell receptors to provide information regarding to extracellular microenvironment to the cells. Therefore, MMPs can regulate the behavior and adaptation of the muscle. The aims of this study were to evaluate the effect of three daily sessions of exhaustive exercise (performed with different recuperative breaks between sessions for six consecutive days) on the MMP-2, MMP-9 and tissue inhibitors of metalloproteinases 1 and 2 (TIMPs) gene expression, as well as, MMP's concentration and biological activities on the rat gastrocnemius muscle red (RG) and white (WG) portions. The animals were sacrificed on exercise-days 1, 3 and 6 and muscle fragments were collected and stored for later analysis through zymography, ELISA and qRT-PCR. Sedentary rats were used as controls. The exercised animals (E) showed an increased performance from the 4th day (p <0.05). There was no statistical difference between the performance of E1 and E2 groups. The genes examined were similarly expressed in response to exercise on the analyzed muscle regions, however, the group E1 have more pronounced changes than E2 when these biomarkers was analyzed. The E1 showed an increased expression of MMP-2 and -9 on the 3rd day of exercise comparing to the control group for RG e WG. Regarding TIMPs 1 and 2, our data showed an increase on their expression in RG and WG responsive to exercise (E1 and E2) during all time experimental points, but this increase was more pronounced in group E1. Furthermore, total concentration of MMP-2 in both groups was significantly reduced when compared to sedentary animals for all time points and muscle regions. The activity of latent and intermediate MMP-2 isoforms were significantly reduced in both exercised groups in the WG and, only, in the E1 to the RG. MMP-9 concentration and activities were not detected in this study. The acute protocol designed for this study induced an increase in the animal performances, regardless of the pauses employed between sessions. The adaptive effect observed in MMP-2 and 9 in the RG and WG was reduced quantitatively and qualitatively, due to the increased expression of both MMPs and TIMPs in group E1 leading to an accelerated remodeling the gastrocnemius extracellular matrix, allowing a significant improvement on performance since the third day onwards. Considering that both rest periods were equally effective to improve physical performance, rest periods of 3 hours between sessions are more adequate due to processes of protein synthesis, once that demands a great amount of energy and depends on the supply of nutrients in quantity and quality suitable for the positive response
Mestrado
Bioquimica
Mestre em Biologia Funcional e Molecular

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38

Otis, Jeffrey Scott. "Skeletal muscle adaptations in cachectic, tumor-bearing rats". Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/26673.

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Cancer cachexia is a debilitating, paraneoplastic syndrome commonly associated with late stage malignancy. It is estimated that ~25% of cancer-related deaths are due directly to complications arising from cachexia (Barton, 2001). Cachexia manifests as severe body wasting, primarily due to the loss of skeletal muscle mass. This study tested the hypothesis that muscle atrophy associated with cancer cachexia could be attenuated by using a unilateral, functional overload (FO) model applied concurrently with tumor development. To accomplish this, Morris hepatoma MH-7777 cells were implanted in adult female, Buffalo rats (n = 12) and allowed to incubate for 6 weeks. FO surgeries (n = 12) were performed five days prior to MH-7777 cell implantation. Over the course of six weeks, healthy, age, sex and strain-matched, vehicle-injected rats (n = 12) gained ~5% of body weight compared to tumor-bearing rats that lost ~6% of body weight when adjusted for tumor mass. Tumor-bearing animals experienced significant atrophy to gastrocnemius, tibialis anterior, extensor digitorum longus, plantaris and diaphragm muscles. FO successfully reversed plantaris muscle atrophy in cachectic, tumor-bearing rats (n=5). FO plantaris masses were ~24% larger than contralateral controls. However, this hypertrophic response was not as great as FO plantaris muscles from healthy, sham-operated controls (~44% larger than contralateral controls, n=5). FO plantaris muscles from tumor-bearing rats had ~1.5 fold increase in myonuclei/fiber ratios compared those of sham-operated, tumor-bearing controls (n = 6). Therefore, cancer cachexia did not prevent myonuclear accretion necessary for skeletal muscle hypertrophy. Little data exists on adaptations to myosin heavy chain (MHC) isoforms in cachectic skeletal muscle. Plantaris muscles from tumor-bearing rats displayed decreased percentages of MHC type I compared to plantaris muscles from vehicle-injected controls (7% vs. 3%, respectively). However, FO plantaris muscles from tumor-bearing rats had an increased percentage of MHC type I and decreased percentage of MHC type IIb compared to sham-operated tumor-bearing rats, adaptations commonly seen in trained muscles. Therefore, cancer cachexia did not prevent the capability of skeletal muscle to respond normally to hypertrophic stimuli. This study also attempted to characterize a mechanism responsible for the hypertrophic response, increased myonuclei/fiber ratio and transition toward a slower MHC profile in FO plantaris muscles from tumor-bearing rats. Recently, the Ca2+/calmodulin-dependent protein phosphatase, calcineurin, has been suggested as a critical factor regulating skeletal muscle growth and fiber-type dependent gene expression (Chin, 1998; Wu, 2000; Olson, 2000; Otis, 2001). The protein content of the catalytic subunit (CaNa) and the regulatory subunit (CaNb) of calcineurin were unchanged in plantaris muscles from tumor-bearing animals compared to healthy controls. Furthermore, total and specific (normalized to CaNa protein content) calcineurin phosphatase activity were not altered in any group. Therefore, calcineurin activity did not appear to be associated with the regulation of the morphological and physiological response of hypertrophying plantaris muscles in cachectic, tumor-bearing rats. Overall, this study indicated that atrophied plantaris muscles from tumor-bearing animals have a reduced capacity to hypertrophy potentially due to a decreased myonuclei/fiber ratio. Furthermore, it is unlikely that changes to mass and MHC isoform expression are associated with calcineurin phosphatase activity.
Ph. D.

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39

Pathare, Neeti C. "Metabolic adaptations following disuse and their impact on skeletal muscle function". [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0010024.

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Thesis (Ph.D.)--University of Florida, 2005.
Typescript. Title from title page of source document. Document formatted into pages; contains 171 pages. Includes Vita. Includes bibliographical references.

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40

O'Keefe, Matthew Phillip. "Adaptations of skeletal muscle insulin signaling following hindlimb suspension". Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280440.

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Hindlimb suspension (HS) in rats was used to study the effects of simulated microgravity on whole-body glucose tolerance and soleus muscle insulin signaling. Following short-term HS (1-day), glucose intolerance and whole-body insulin resistance developed. Insulin resistance was also identified at the skeletal muscle level, with the type I soleus showing more insulin resistance than the type II extensor digitorum longus (EDL). Examination of insulin signaling components in the soleus revealed a tendency towards a decrease in the expression of the p85 regulatory subunit of phosphatidylinositol-3 kinase (PI3-K) in addition to a decrease in the basal phosphorylation levels of Akt. These changes may contribute to the observed insulin resistance in the soleus, but clearly other factors likely also contribute. The data from the whole-body and muscle studies after 1-day HS did not clearly identify the factors responsible for the observed glucose intolerance and reduced glucose uptake. However, because both the soleus and EDL exhibited decreased insulin-mediated glucose uptake, there may be a circulating factor responsible for the observed insulin resistance and glucose intolerance. The whole-body glucose intolerance and muscle insulin resistance was no longer apparent after 3-day HS. Interestingly, 7-day HS resulted in the development of enhanced whole-body insulin sensitivity. In both 3-day and 7-day HS soleus, insulin action on glucose transport was increased. In addition, GLUT-4 protein and activities of hexokinase and citrate synthase were increased with prolonged HS. Following 3-day HS, expression of insulin receptor substrate-1 (IRS-1) and -2 (IRS-2) were decreased. However, assessment of the functionality of signaling proteins indicated insulin-induced increases in tyrosine phosphorylation per unit IRS-1 protein, IRS-1 association with p85, and Akt phosphorylation. The PI3-kinase inhibitor wortmannin did not completely block the observed increases in insulin-mediated glucose transport in 3-day and 7-day HS soleus, indicating the small role of a P13-K independent mechanism. These results indicate that prolonged HS (3-7 days) can alter the functionality of specific insulin signaling components in the soleus muscle, accounting for most of the increase in insulin-stimulated glucose uptake induced by simulated weightlessness.

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41

Singh, François. "Skeletal muscle toxicity and statins : role of mitochondrial adaptations". Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAJ050/document.

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Bien que les statines forment la classe d'hypolipidémiants la plus utilisée, une toxicité musculaire a été reportée, pouvant ainsi provoquer l’apparition d’une myopathie. Dans la première partie, nous avons montré chez l’Homme et l’animal que les statines inhibent directement la chaine respiratoire mitochondriale, et induisent la production de radicaux libres dérivés de l’oxygène (RLO), qui active les voies apoptotiques dans les muscles glycolytiques, alors que les muscles oxydatifs ne sont pas atteints. Nous avons ensuite montré in vitro que le stress réducteur peut engendrer une oxydation mitochondriale, pouvant conduire à une activation de la voie de biogenèse mitochondriale. De plus l’augmentation du contenu mitochondrial induite a permis de protéger les cellules contre l’apoptose induite par les statines. Enfin, nous avons montré in vivo que l’induction des voies de biogenèse mitochondriale est nécessaire à la tolérance des statines dans les muscles oxydatifs. En conclusion, le phénotype mitochondrial, tant au niveau quantitatif que qualitatif, semble être un facteur clé dans l’apparition de la myopathie aux statines
Although statins are the most prescribed class of lipid-lowering agents, adverse muscular toxicity has been reported, which can lead to the appearance of a myopathy. In the first part, we showed in Humans and animals that statins inhibit directly the mitochondrial respiratory chain, and induce the production of reactive oxygen species (ROS), that trigger apoptotic pathways in glycolytic skeletal muscles, whereas oxidative muscles are not impaired. We then showed in vitro that reductive stress can provoke mitochondrial oxidation, that could lead to an activation of mitochondrial biogenesis pathways. Moreover, the consequent increase in mitochondrial content enabled to protect cells against statin-induced apoptosis. Finally, we showed in vivo that the induction of mitochondrial biogenesis is necessary for statin tolerance in oxidative skeletal muscles. In conclusion, mitochondrial phenotype, both quantitatively and qualitatively, seems to be a key factor in the appearance of statin myopathy

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42

Rafati, Nima. "Exploring genetic diversity in natural and domestic populations through next generation sequencing". Doctoral thesis, Uppsala universitet, Institutionen för medicinsk biokemi och mikrobiologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-315032.

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Studying genetic diversity in natural and domestic populations is of major importance in evolutionary biology. The recent advent of next generation sequencing (NGS) technologies has dramatically changed the scope of these studies, enabling researchers to study genetic diversity in a whole-genome context. This thesis details examples of studies using NGS data to: (i) characterize evolutionary forces shaping the genome of the Atlantic herring, (ii) detect the genetic basis of speciation and domestication in the rabbit, and, (iii) identify mutations associated with skeletal atavism in Shetland ponies. The Atlantic herring (Clupea harengus) is the most abundant teleost species inhabiting the North Atlantic. Herring has seasonal reproduction and is adapted to a wide range of salinity (3-35‰) throughout the Baltic Sea and Atlantic Ocean. By using NGS data and whole-genome screening of 20 populations, we revealed the underlying genetic architecture for both adaptive features. Our results demonstrated that differentiated genomic regions have evolved by natural selection and genetic drift has played a subordinate role. The European rabbit (Oryctolagus cuniculus) is native to the Iberian Peninsula, where two rabbit subspecies with partial reproductive isolation have evolved. We performed whole genome sequencing to characterize regions of reduced introgression. Our results suggest key role of gene regulation in triggering genetic incompatibilities in the early stages of reproductive isolation. Moreover, we studied gene expression in testis and found misregulation of many genes in backcross progenies that often show impaired male fertility. We also scanned whole genome of wild and domestic populations and identified differentiated regions that were enriched for non-coding conserved elements. Our results indicated that selection has acted on standing genetic variation, particularly targeting genes expressed in the central nervous system. This finding is consistent with the tame behavior present in domestic rabbits, which allows them to survive and reproduce under the stressful non-natural rearing conditions provided by humans. In Shetland ponies, abnormally developed ulnae and fibulae characterize a skeletal deformity known as skeletal atavism. To explore the genetic basis of this disease, we scanned the genome using whole genome resequencing data. We identified two partially overlapping large deletions in the pseudoautosomal region (PAR) of the sex chromosomes that remove the entire coding sequence of the SHOX gene and part of CRLF2 gene. Based on this finding, we developed a diagnostic test that can be used as a tool to eradicate this inherited disease in horses.

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43

Bowser, Suzanne Mae. "Skeletal muscle metabolic adaptations in response to an acute high fat diet". Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/82030.

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Macronutrient metabolism plays an essential role in the overall health of an individual. Depending on a number of variables, for example, diet, fitness level, or metabolic disease state, protein, carbohydrate and fat have varying capacities to be oxidized and balanced. Further, when analyzing the oxidation of carbohydrate and fat in the skeletal muscle specifically, carbohydrate balance happens quite rapidly, while fat balance does not. The ability of skeletal muscle to adapt and respond to various nutrient states is critical to maintaining healthy metabolic function. Habitual high fat intake has been associated with reduced oxidative capacity, insulin resistance, increased gut permeability, inflammation, and other risk factors often preceding metabolic disease states. The disruption of gut function leads to gut permeability and increases endotoxins released into circulation. Endotoxins have been shown to play an important role in obesity-related whole body and tissue specific metabolic perturbations. Each of these disrupted metabolic processes is known to associate with obesity, metabolic syndrome and diabetes. To date, limited research has investigated the role of high fat diet on skeletal muscle substrate oxidation and its relationship to gut permeability and endotoxins. The purpose of this study was to determine the effects of an acute, five-day, isocaloric high fat diet (HFD) on skeletal muscle substrate metabolism in healthy non-obese humans. An additional purpose was to determine the effects of a HFD on gut permeability and blood endotoxins on healthy, non-obese, sedentary humans. Thirteen college age males were fed a control diet for two weeks, followed by five days of an isocaloric HFD. To assess the effects of a HFD on skeletal muscle metabolic adaptability and postprandial endotoxin levels, subjects underwent a high fat meal challenge before and after a HFD. Muscle biopsies were obtained; blood was collected; insulin sensitivity was assessed via intravenous glucose tolerance test; and intestinal permeability was assessed via the four-sugar probe test before and after the HFD. Postprandial glucose oxidation and fatty acid oxidation in skeletal muscle increased before the HFD intervention but was decreased after. Skeletal muscle in vitro assay of metabolic flexibility was significantly blunted following the HFD. Insulin sensitivity and intestinal permeability were not affected by HFD, but fasting endotoxin was significantly higher following the HFD. These findings demonstrate that in young, healthy males, following five days of an isocaloric high fat diet, skeletal muscle metabolic adaptation is robust. Additionally, increased fasting endotoxin independent of gut permeability changes are potentially a contributor to the inflammatory state that disrupts substrate oxidation. These findings suggest that even short-term changes in dietary fat consumption have profound effects on skeletal muscle substrate metabolism and fasting endotoxin levels, independent of positive energy balance and whole-body insulin sensitivity.
Ph. D.

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44

Lundberg, Tommy. "The Effects of Aerobic Exercise on Human Skeletal Muscle Adaptations to Resistance Exercise". Doctoral thesis, Mittuniversitetet, Avdelningen för hälsovetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-21917.

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Aerobic exercise (AE) may interfere with muscle adaptations induced by resistance exercise (RE). Three experimental campaigns were conducted to explore the influence of AE on molecular, functional and muscular adaptations to acute and chronic RE. Twenty-nine men performed unilateral knee extensor RE preceded by AE (AE+RE). The contralateral leg did RE only. First, the influence of acute AE on muscle molecular responses to RE performed 6 h later was studied. Subsequently, this exercise regimen was implemented over 5 weeks training. The relationships between acute and chronic outcomes were examined and molecular responses to acute exercise were assessed in untrained and trained muscle. Finally, acute and chronic responses to AE+RE, interspersed by only 15 min recovery, were investigated.Phosphorylation of mTOR and p70S6K was greater after AE+RE than after RE. In parallel, myostatin was suppressed for a longer time after AE+RE. These results suggest that AE+RE enhance skeletal muscle anabolic environment more than RE alone (Paper I). After 5 weeks training, improvements in muscle strength and power were similar across legs. However, AE+RE prompted a greater increase in muscle size than RE, suggesting that AE potentiates the hypertrophic stimulus to RE training without altering muscle function progress (Paper II). Consistent with changes in whole-muscle size, AE+RE showed greater anabolic molecular responses than RE. As chronic training blunted this effect, it appears that AE offers a synergistic hypertrophic stimulus to RE only during short-term training (Paper III). Although putative regulators of hypertrophy such as p70S6K, myostatin and PGC-1a4 were examined, no molecular marker correlated with changes in muscle size, strength or power induced by training. Hence, this study challenges the concept that single molecular markers are viable predictors of training-induced muscle adaptations (Paper III–IV). When recovery time between exercise bouts was reduced to 15 min, AE+RE still produced a more substantial increase in muscle size than RE. However, progression of concentric strength was blunted. Thus, while restored muscle function between exercise bouts is a prerequisite for achieving maximal gains in strength and power, incomplete recovery appears not to compromise muscle hypertrophy (Paper V).Collectively, the results suggest that outcomes of AE+RE are impacted by chronic training and time allowed for recovery between exercise modes. Yet, the current study offers no support to the view that AE interferes with muscle hypertrophy induced by RE.

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45

Mattern, Craig O. "MAXIMAL LACTATE STEADY STATE: INFLUENCE OF THE AGE-RELATED ADAPTATIONS OF SKELETAL MUSCLE". Connect to this title online, 2002. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1039034888.

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Thesis (Ph. D.)--Ohio State University, 2002.
Title from first page of PDF file. Document formatted into pages; contains xii, 49 p.; also includes graphics (some col.) Includes bibliographical references (p. 39-44). Available online via OhioLINK's ETD Center

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46

Carroll, Kevin M., Caleb D. Bazyler, Jake R. Bernards, Christopher B. Taber, Charles A. Stuart, Brad H. DeWeese, Kimitake Sato e Michael H. Stone. "Skeletal Muscle Fiber Adaptations Following Resistance Training Using Repetition Maximums or Relative Intensity". Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/etsu-works/5786.

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The purpose of the study was to compare the physiological responses of skeletal muscle to a resistance training (RT) program using repetition maximum (RM) or relative intensity (RISR). Fifteen well-trained males underwent RT 3 d·wk−1 for 10 weeks in either an RM group (n = 8) or RISR group (n = 7). The RM group achieved a relative maximum each day, while the RISR group trained based on percentages. The RM group exercised until muscular failure on each exercise, while the RISR group did not reach muscular failure throughout the intervention. Percutaneous needle biopsies of the vastus lateralis were obtained pre-post the training intervention, along with ultrasonography measures. Dependent variables were: Fiber type-specific cross-sectional area (CSA); anatomical CSA (ACSA); muscle thickness (MT); mammalian target of rapamycin (mTOR); adenosine monophosphate protein kinase (AMPK); and myosin heavy chains (MHC) specific for type I (MHC1), type IIA (MHC2A), and type IIX (MHC2X). Mixed-design analysis of variance and effect size using Hedge’s g were used to assess within- and between-group alterations. RISR statistically increased type I CSA (p = 0.018, g = 0.56), type II CSA (p = 0.012, g = 0.81), ACSA (p = 0.002, g = 0.53), and MT (p < 0.001, g = 1.47). RISR also yielded a significant mTOR reduction (p = 0.031, g = −1.40). Conversely, RM statistically increased only MT (p = 0.003, g = 0.80). Between-group effect sizes supported RISR for type I CSA (g = 0.48), type II CSA (g = 0.50), ACSA (g = 1.03), MT (g = 0.72), MHC2X (g = 0.31), MHC2A (g = 0.87), and MHC1 (g = 0.59); with all other effects being of trivial magnitude (g < 0.20). Our results demonstrated greater adaptations in fiber size, whole-muscle size, and several key contractile proteins when using RISR compared to RM loading paradigms.

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47

Toma, Kumika. "Effects of High-Carbohydrate and Low-Fat Versus High-Protein and Low-Carbohydrate Diets on High-Intensity Aerobic Exercise". View abstract, 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3372362.

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48

Slater, Graham James. "Biomechanical adaptations to predation in the carnivoran craniofacial skeleton". Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1997615301&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.

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49

Kirby, Tyler. "GLOBAL-SCALE ANALYSIS OF THE DYNAMIC TRANSCRIPTIONAL ADAPTATIONS WITHIN SKELETAL MUSCLE DURING HYPERTROPHIC GROWTH". UKnowledge, 2015. http://uknowledge.uky.edu/physiology_etds/22.

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Skeletal muscle possesses remarkable plasticity in responses to altered mechanical load. An established murine model used to increase mechanical load on a muscle is the surgical removal of the gastrocnemius and soleus muscles, thereby placing a functional overload on the plantaris muscle. As a consequence, there is hypertrophic growth of the plantaris muscle. We used this model to study the molecular mechanisms regulating skeletal muscle hypertrophy. Aged skeletal muscle demonstrates blunted hypertrophic growth in response to functional overload. We hypothesized that an alteration in gene expression would contribute to the blunted hypertrophic response observed with aging. However, the difference in gene expression was modest, with cluster analysis showing a similar pattern of expression between the two groups. Despite ribosomal protein gene expression being higher in the aged group, ribosome biogenesis was significantly lower in aged compared with young skeletal muscle in response to the hypertrophic stimulus (50% versus 2.5-fold, respectively). The failure to fully up-regulate pre-47S ribosomal RNA (rRNA) expression in old skeletal muscle undergoing hypertrophy indicated ribosomal DNA transcription by RNA polymerase I was impaired. Contrary to our hypothesis, the findings of the study suggest that impaired ribosome biogenesis was a primary factor underlying the blunted hypertrophic response observed in old skeletal muscle rather than dramatic differences in gene expression. As it appears ribosomal biogenesis may limit muscle hypertrophy, we assessed the dynamic changes in global transcriptional output during muscle hypertrophy, as the majority of global transcription is dedicated to ribosome biogenesis during periods of rapid growth. Metabolic labeling of nascent RNA using 5-ethynyl uridine permitted the assessment of cell type specific changes in global transcription and how this transcription is distributed within the myofiber. Using this approach, we demonstrate that myofibers are the most transcriptionally active cell-type in skeletal muscle, and furthermore, myonuclei are able to dramatically upregulate global transcription during muscle hypertrophy. Interestingly, the myonuclear accretion that occurs with hypertrophy actually results in lower transcriptional output across nuclei within the muscle fiber relative to sham conditions. These findings argue against the notion that nuclear accretion in skeletal muscle is necessary to increase the transcriptional capacity of the cell in order to support a growth response.

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50

Williamson, David L. "Effects of progressive resistance training on skeletal muscle protein isoform adaptations in elderly men". Virtual Press, 1999. http://liblink.bsu.edu/uhtbin/catkey/1136712.

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Progressive resistance training (PRT) in the elderly has commonly used ATPase histochemistry to evaluate fiber type changes, but evidence shows there are myosin heavy chain (MHC) hybrids in aging muscle that cannot be classified by histochemistry. The purpose of this study was to assess the MHC and whole muscle alterations following a 12-week PRT protocol. Seven healthy men (age=74.0±4.7, weight=74.6±13.5kg) underwent testing for 1-repetition maximum (1-RM), whole muscle (thigh) crosssectional area (CSA) by computed tomography, and a needle muscle biopsy from the vastus lateralis for analysis of MHC, pre- and post-training. The PRT consisted of 2 sets of 10 repetitions, and a third set to volitional exhaustion at 80% 1-RM, 3 days per week for 12 weeks. Muscle ATPase histochemistry analysis for distribution did not significantly differ following training. Muscle samples were freeze dried and dissected for MHC analysis (sodium dodecyl sulfate-polyacrylamide gel electrophoresis (5% gel) and silver stained; 224.0±11.2 and 213.0±8.1 fibers/subject pre-/post-training; total fibers analyzed=3059). MHC analysis demonstrated significant increases in MHC I proportion (10.4%; P<0.05), and significant decreases in MHC UIIa (9.0%; P<0.05), UIIa/x (0.9%; P<0.05), and IIa/x (8.9%; P<0.05) isofroms, along with no change in the MHC Ila and IIx isoforms, pre- versus post-training. In addition, 1-RM (51.9%; P<0.05) and CSA (5.9%; P<0.05) increased from pre- to post-testing. This data supports previous whole muscle changes, more important, is the increase in MHC I and decrease in MHC I/IIa, I/IIa/IIx, and IIa/x hybrids. The myosin light chain 3f (MLC3f) to MLC 2 ratio did not change with the PRT in either the MHC I or MHC IIa isoforms, although there was a significantly greater amount of MLC 3f in the MHC Ila versus the MHC I fibers (p<0.05), pre- and post-training. The myosin isofrom data provides support that aging muscle has the plasticity to adapt in a manner unlike that of young muscle.
School of Physical Education

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