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Full-Text Articles in Medicine and Health Sciences

No Evidence Of Direct Association Between Glut4 And Glycogen In Human Skeletal Muscle, Robyn M. Murphy, Marcelo Flores-Opazo, Barnaby P. Frankish, Andrew Garnham, David Stapleton, Mark Hargreaves Jan 2018

No Evidence Of Direct Association Between Glut4 And Glycogen In Human Skeletal Muscle, Robyn M. Murphy, Marcelo Flores-Opazo, Barnaby P. Frankish, Andrew Garnham, David Stapleton, Mark Hargreaves

Faculty of Health Sciences Publications

Previous studies have demonstrated that exercise increases whole body and skeletal muscle insulin sensitivity that is linked with increased GLUT4 at the plasma membrane following insulin stimulation and associated with muscle glycogen depletion. To assess the potential direct association between muscle glycogen and GLUT4, seven untrained, male subjects exercised for 60 min at ~75% VO2 peak, with muscle samples obtained by percutaneous needle biopsy immediately before and after exercise. Exercise reduced muscle glycogen content by ~43%. An ultracentrifugation protocol resulted in a ~2‐3‐fold enriched glycogen fraction from muscle samples for analysis. Total GLUT4 content was unaltered by exercise ...


A Novel In Vitro Model For The Assessment Of Postnatal Myonuclear Accretion, Anita Kneppers, Lex B. Verdijk, Chiel De Theije, Mark Corten, Ellis Gielen, Luc Van Loon, Annemie Schols, Ramon Langen Jan 2018

A Novel In Vitro Model For The Assessment Of Postnatal Myonuclear Accretion, Anita Kneppers, Lex B. Verdijk, Chiel De Theije, Mark Corten, Ellis Gielen, Luc Van Loon, Annemie Schols, Ramon Langen

Faculty of Health Sciences Publications

Background: Due to the post-mitotic nature of myonuclei, postnatal myogenesis is essential for skeletal muscle growth, repair, and regeneration. This process is facilitated by satellite cells through proliferation, differentiation, and subsequent fusion with a pre-existing muscle fiber (i.e., myonuclear accretion). Current knowledge of myogenesis is primarily based on the in vitro formation of syncytia from myoblasts, which represents aspects of developmental myogenesis, but may incompletely portray postnatal myogenesis. Therefore, we aimed to develop an in vitro model that better reflects postnatal myogenesis, to study the cell intrinsic and extrinsic processes and signaling involved in the regulation of postnatal myogenesis ...


Exercise And Glut4 In Human Subcutaneous Adipose Tissue, Marcelo Flores-Opazo, Eva Boland, Andrew Garnham, Robyn M. Murphy, Sean L. Mcgee, Mark Hargreaves Jan 2018

Exercise And Glut4 In Human Subcutaneous Adipose Tissue, Marcelo Flores-Opazo, Eva Boland, Andrew Garnham, Robyn M. Murphy, Sean L. Mcgee, Mark Hargreaves

Faculty of Health Sciences Publications

To examine the effect of acute and chronic exercise on adipose tissue GLUT4 expression, a total of 20 healthy, male subjects performed one of two studies. Ten subjects performed cycle ergometer exercise for 60 min at 73 ± 2% VO2 peak and abdominal adipose tissue samples were obtained immediately before and after exercise and after 3 h of recovery. Another 10 subjects completed 10 days of exercise training, comprising a combination of six sessions of 60 min at 75% VO2 peak and four sessions of 6 × 5 min at 90% VO2 peak, separated by 3 min at 40% VO2 peak. Abdominal ...


Muscle Atrophy Due To Nerve Damage Is Accompanied By Elevated Myofibrillar Protein Synthesis Rates, Henning Langer, Joan M. Senden, Annemie P. Gijsen, Stefan Kempa, Luc Van Loon, Simone Spuler Jan 2018

Muscle Atrophy Due To Nerve Damage Is Accompanied By Elevated Myofibrillar Protein Synthesis Rates, Henning Langer, Joan M. Senden, Annemie P. Gijsen, Stefan Kempa, Luc Van Loon, Simone Spuler

Faculty of Health Sciences Publications

Muscle loss is a severe complication of many medical conditions such as cancer, cardiac failure, muscular dystrophies, and nerve damage. The contribution of myofibrillar protein synthesis (MPS) to the loss of muscle mass after nerve damage is not clear. Using deuterium oxide (D2O) labeling, we demonstrate that MPS is significantly increased in rat m. tibialis anterior (TA) compared to control (3.23 ± 0.72 [damaged] to 2.09 ± 0.26%∗day−1 [control]) after 4 weeks of nerve constriction injury. This is the case despite substantial loss of mass of the TA (350 ± 96 mg [damaged] to 946 ± 361 mg ...


Interactive Roles For Ampk And Glycogen From Cellular Energy Sensing To Exercise Metabolism, Natalie Janzen, Jamie Whitfield, Nolan Hoffman Jan 2018

Interactive Roles For Ampk And Glycogen From Cellular Energy Sensing To Exercise Metabolism, Natalie Janzen, Jamie Whitfield, Nolan Hoffman

Faculty of Health Sciences Publications

The AMP-activated protein kinase (AMPK) is a heterotrimeric complex with central roles in cellular energy sensing and the regulation of metabolism and exercise adaptations. AMPK regulatory β subunits contain a conserved carbohydrate-binding module (CBM) that binds glycogen, the major tissue storage form of glucose. Research over the past two decades has revealed that the regulation of AMPK is impacted by glycogen availability, and glycogen storage dynamics are concurrently regulated by AMPK activity. This growing body of research has uncovered new evidence of physical and functional interactive roles for AMPK and glycogen ranging from cellular energy sensing to the regulation of ...


Striated Muscle Activator Of Rho Signalling (Stars) Is Reduced In Ageing Human Skeletal Muscle And Targeted By Mir-628-5p, Andrew Russell, M. A. Wallace, M. Kalanon, Evelyn Zacharewicz, P. A.D. Gatta, Andrew Garnham, Séverine Lamon Jan 2017

Striated Muscle Activator Of Rho Signalling (Stars) Is Reduced In Ageing Human Skeletal Muscle And Targeted By Mir-628-5p, Andrew Russell, M. A. Wallace, M. Kalanon, Evelyn Zacharewicz, P. A.D. Gatta, Andrew Garnham, Séverine Lamon

Faculty of Health Sciences Publications

Aim: The striated muscle activator of Rho signalling (STARS) is a muscle-specific actin-binding protein. The STARS signalling pathway is activated by resistance exercise and is anticipated to play a role in signal mechan-otransduction. Animal studies have reported a negative regulation of STARS signalling with age, but such regulation has not been investigated in humans. Methods: Ten young (18–30 years) and 10 older (60–75 years) subjects completed an acute bout of resistance exercise. Gene and protein expres-sion of members of the STARS signalling pathway and miRNA expression of a subset of miRNAs, predicted or known to target members of ...


Muscle Fiber Capillarization As Determining Factor On Indices Of Insulin Sensitivity In Humans, Tim Snijders, Joshua P. Nederveen, Lex B. Verdijk, Alfons J.H.M. Houben, Gijs H. Goossens, Gianna Parise, Luc Van Loon Jan 2017

Muscle Fiber Capillarization As Determining Factor On Indices Of Insulin Sensitivity In Humans, Tim Snijders, Joshua P. Nederveen, Lex B. Verdijk, Alfons J.H.M. Houben, Gijs H. Goossens, Gianna Parise, Luc Van Loon

Faculty of Health Sciences Publications

To investigate the association between muscle fiber capillarization and indices of insulin sensitivity in healthy older adults. A skeletal muscle biopsy was taken from the m. vastus lateralis of 22 healthy (nondiabetic) male older adults. In addition, all participants underwent an Oral Glucose Tolerance Test (OGTT). Muscle fiber capillarization was assessed by immunohistochemistry. Participants were divided into a group with relatively low (LOW) or high (HIGH) muscle fiber capillarization (capillary-to-fiber perimeter exchange (CFPE) index), based on the median value for the entire group. All participants were healthy, nonobese, and had a normal glucose tolerance, according to the individual OGTT results ...


Presleep Protein Ingestion Does Not Compromise The Muscle Protein Synthetic Response To Protein Ingested The Following Morning [Accepted Manuscript], Benjamin T. Wall, Nicholas A. Burd, Rinske Franssen, Stefan H. M. Gorissen, Tim Snijders, Joan M. Senden, Annemie P. Gijsen, Luc Van Loon Jan 2016

Presleep Protein Ingestion Does Not Compromise The Muscle Protein Synthetic Response To Protein Ingested The Following Morning [Accepted Manuscript], Benjamin T. Wall, Nicholas A. Burd, Rinske Franssen, Stefan H. M. Gorissen, Tim Snijders, Joan M. Senden, Annemie P. Gijsen, Luc Van Loon

Faculty of Health Sciences Publications

Protein ingestion before sleep augments postexercise muscle protein synthesis during overnight recovery. It is unknown whether postexercise and presleep protein consumption modulates postprandial protein handling and myofibrillar protein synthetic responses the following morning. Sixteen healthy young ( 24 ± 1 yr ) men performed unilateral resistance-type exercise ( contralateral leg acting as a resting control ) at 2000. Participants ingested 20 g of protein immediately after exercise plus 60 g of protein presleep ( PRO group; n = 8 ) or equivalent boluses of carbohydrate ( CON; n = 8 ). The subsequent morning participants received primed, continuous infusions of l-[ring-2H5]phenylalanine and l-[1-13C]leucine combined with ingestion of ...


Muscle Fibre Capillarization Is A Critical Factor In Muscle Fibre Hypertrophy During Resistance Exercise Training In Older Men, Tim Snijders, Joshua P. Nederveen, Sophie Joanisse, Marika Leenders, Lex B. Verdijk, Luc J. C. Van Loon, Gianni Parise Jan 2016

Muscle Fibre Capillarization Is A Critical Factor In Muscle Fibre Hypertrophy During Resistance Exercise Training In Older Men, Tim Snijders, Joshua P. Nederveen, Sophie Joanisse, Marika Leenders, Lex B. Verdijk, Luc J. C. Van Loon, Gianni Parise

Faculty of Health Sciences Publications

Background Adequate muscle fibre perfusion is critical for the maintenance of muscle mass, it is essential in the rapid delivery of oxygen, nutrients and growth factors to the muscle, stimulating muscle fibre growth. Muscle fibre capillarization is known to decrease substantially with advancing age. However, whether (relative) low muscle fibre capillarization negatively impacts the muscle hypertrophic response following resistance exercise training in older adults is unknown. Methods Twenty-two healthy older men (71 ± 1 years) performed 24 weeks of progressive resistance type exercise training. To assess the change in muscle fibre characteristics, percutaneous biopsies from the vastus lateralis muscle were taken ...


Architectural Adaptations Of Muscle To Training And Injury: A Narrative Review Outlining The Contributions By Fascicle Length, Pennation Angle And Muscle Thickness [Accepted Manuscript], Ryan G. Timmins, Anthony J. Shield, Morgan D. Williams, Christian Lorenzen, David Opar Jan 2016

Architectural Adaptations Of Muscle To Training And Injury: A Narrative Review Outlining The Contributions By Fascicle Length, Pennation Angle And Muscle Thickness [Accepted Manuscript], Ryan G. Timmins, Anthony J. Shield, Morgan D. Williams, Christian Lorenzen, David Opar

Faculty of Health Sciences Publications

Background: The architectural characteristics of muscle (fascicle length, pennation angle muscle thickness) respond to varying forms of stimuli ( eg, training, immobilisation and injury ). Architectural changes following injury are thought to occur in response to the restricted range of motion experienced during rehabilitation and the associated neuromuscular inhibition. However, it is unknown if these differences exist prior to injury, and had a role in injury occuring ( prospectively ), or if they occur in response to the incident itself ( retrospectively ). Considering that the structure of a muscle will influence how it functions, it is of interest to understand how these architectural variations may ...


May Bed Rest Cause Greater Muscle Loss Than Limb Immobilization? [Accepted Manuscript], Marlou L. Dirks, E. M. P. Backx, Benjamin T. Wall, Lex B. Verdijk, Luc Van Loon Jan 2016

May Bed Rest Cause Greater Muscle Loss Than Limb Immobilization? [Accepted Manuscript], Marlou L. Dirks, E. M. P. Backx, Benjamin T. Wall, Lex B. Verdijk, Luc Van Loon

Faculty of Health Sciences Publications

Bed rest, as often occurs following surgery or during (critical) illness, may result in greater muscle loss than local muscle disuse, not only because of the amount of muscle tissue that is subjected to disuse, but also because of various systemic factors that may accelerate muscle atrophy. These factors could include hormonal changes or (low-grade) systemic inflammation. In medical research, experimental (whole-body) bed rest and (local) limb immobilization are typically applied in healthy volunteers to investigate the impact of disuse on the loss of muscle mass and strength. Previous work, based on combined results of separate studies, has suggested that ...


Skeletal Muscle Ampk Is Essential For The Maintenance Of Fndc5 Expression, James S. V. Lally, Rebecca J. Ford, Jasper Johar, Justin D. Crane, Bruce Ernest Kemp, Gregory R. Steinberg Jan 2015

Skeletal Muscle Ampk Is Essential For The Maintenance Of Fndc5 Expression, James S. V. Lally, Rebecca J. Ford, Jasper Johar, Justin D. Crane, Bruce Ernest Kemp, Gregory R. Steinberg

Faculty of Health Sciences Publications

Fibronectin type III domain‐containing protein 5 (FNDC5) expression is controlled by the transcriptional co‐activator, peroxisome proliferator‐activated receptor gamma, coactivator 1 alpha (PGC1α). FNDC5 expression has been shown to be increased in muscle in response to endurance exercise in some but not all studies, therefore a greater understanding of the mechanisms controlling this process are needed. The AMP‐activated protein kinase (AMPK) is activated by exercise in an intensity dependent manner and is an important regulator of PGC1α activity; therefore, we explored the role of AMPK in the regulation of FNDC5 using AMPK β1β2 double muscle‐null mice ...


Post-Exercise Protein Synthesis Rates Are Only Marginally Higher In Type I Compared With Type Ii Muscle Fibres Following Resistance-Type Exercise, René Koopman, Benjamin G. Gleeson, Annemie P. Gijsen, Bart B. L. Groen, Joan M. G. Senden, Michael J. Rennie, Luc J. C. Van Loon Jan 2011

Post-Exercise Protein Synthesis Rates Are Only Marginally Higher In Type I Compared With Type Ii Muscle Fibres Following Resistance-Type Exercise, René Koopman, Benjamin G. Gleeson, Annemie P. Gijsen, Bart B. L. Groen, Joan M. G. Senden, Michael J. Rennie, Luc J. C. Van Loon

Faculty of Health Sciences Publications

We examined the effect of an acute bout of resistance exercise on fractional muscle protein synthesis rates in human type I and type II muscle fibres. After a standardised breakfast (31 ± 1 kJ kg−1 body weight, consisting of 52 Energy% (En%) carbohydrate, 34 En% protein and 14 En% fat), 9 untrained men completed a lower-limb resistance exercise bout (8 sets of 10 repetitions leg press and leg extension at 70% 1RM). A primed, continuous infusion of l-[ring-13C6]phenylalanine was combined with muscle biopsies collected from both legs immediately after exercise and after 6 h of post-exercise recovery. Single ...