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Personal profile

Research

My main interest is in studying determinants of the contractile characteristics of muscle (i.e. muscle peak and steady state power and the length range of active force exertion). Normally the force that a muscle can exert is strictly regulated to movement in daily live. However, this appears not to be the case in chronic diseases of the heart and respiratory muscles or in neuromuscular disorders such a Duchenne dystrophy and cerebral pareses. These pathologies are all associated with muscle weakness, which is sometimes length-dependent. Therefore my second interest is in the basic regulatory mechanisms underlying adaptation. I focus on the following questions: 1) What are the mechanical and metabolic stimuli for adaptation of muscle size and oxidative capacity and 2) via which signaling pathways are these stimuli regulating synthesis and degradation of contractile and mitochondrial proteins? These processes are investigated at different levels of organization: 1) the myoblast in vitro, 2) the isolated mature muscle fiber (ex vivo culture of Xenopus muscle fibres), (3) whole muscle in situ and in vivo (mouse, rat, Xenopus and human).

Basic research
Adaptation of muscle fiber size by mechanotransduction, expression of growth factors and therole of the extracellular matrix
Mechanical loading is a major stimulus for muscle hypertrophy and addition of sarcomeres in series. The mechanisms via which muscle fibers sense mechanical stimuli and how these stimuli regulate the rate of protein synthesis via their downstream signaling pathways is still an enigma. Evidence suggests that the extracellular matrix plays an important role in the force transmission from muscle fiber to bone (myofascial force transmission). We are currently testing the hypothesis that myofascial pathways are involved in activating muscle stem cells (satellite cells) and biochemical signaling pathways regulating mRNA transcription, translation and degradation of proteins. As mechanical loading of muscle fibers stimulates the expression of growth factors (e.g. insulin-like growth factors and myostatin) and cytokines (interleuking-6 and adiponectin) in muscle fibers and these factors have a strong ability to alter the rates of synthesis and/or degradation of muscle proteins, these factors receive particular interest. We use ex vivo and in vivo models to test the independent effects of particular stimuli as well as their interplay.

Adaptation of the oxidative capacity
The most important determinant of steady state power of muscle (or fatigability) is the mitochondrial density in the muscle fibers. The trade off of a high oxidative capacity is a limitation of the cross-sectional size of a muscle fiber. Muscle fiber size and mitochondrial density are inversely related. We investigate the mechanisms underlying the interactions between the regulation of muscle fiber size and mitochondrial density.

Applied research
I am involved in several clinical projects. We investigate muscle geometry in children with neurological disorders such as cerebral pareses and brachial plexus injuries. We developed a novel 3D ultrasound technique for standardized in vivo measurement of the muscle geometry. Further we investigate how muscle size and oxidative capacity adapt in patients suffering from cachexia and chronic inflammatory diseases such as heart failure and metabolic syndrome and how training may counteract these adaptations.

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  • 4 Similar Profiles
Muscles Medicine & Life Sciences
Muscle Chemical Compounds
Skeletal Muscle Medicine & Life Sciences
Hypertrophy Medicine & Life Sciences
Cerebral Palsy Medicine & Life Sciences
Skeletal Muscle Fibers Medicine & Life Sciences
muscles Agriculture & Biology
Myoglobin Medicine & Life Sciences

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Selected Research Output 1998 2018

Reinforcement versus fluidization in cytoskeletal mechanoresponsiveness

Krishnan, R., Park, C. Y., Lin, Y. C., Mead, J., Jaspers, R. T., Trepat, X., Lenormand, G., Tambe, D., Smolensky, A. V., Knoll, A. H., Butler, J. P. & Fredberg, J. J. 2009 In : PLoS One. 4, 5, p. e5486 8 p.

Research output: Contribution to journalArticle

Open Access
File
traction (mechanics)
Fluidization
Traction
Eukaryotic Cells
Reinforcement
Open Access
File
Muscles
Sarcomeres
Immobilization
Hypogravity
Tenotomy

The muscle fiber type-fiber size paradox: hypertrophy or oxidative metabolism?

van Wessel, T., de Haan, A., van der Laarse, W. J. & Jaspers, R. T. 2010 In : European Journal of Applied Physiology. 110, 4, p. 665-694

Research output: Contribution to journalArticle

Open Access
File
Hypertrophy
Muscles
Proteins
Fatigue
Contractile Proteins
Cadaver
Ultrasonography
Muscles
Skeletal Muscle
Aponeurosis

Transcriptome analysis of the response to chronic constant hypoxia in zebrafish hearts

Marques, I. J., Leito, J. T., Spaink, H. P., Testerink, J., Jaspers, R. T., Witte, F., van den Berg, S. & Bagowski, C. P. 2008 In : Journal of Comparative Physiology B. Biochemical, Systemic, and Environmental Physiology. 178, 1, p. 77-92

Research output: Contribution to journalArticle

Open Access
Gene Expression Profiling
Zebrafish
hypoxia
transcriptomics
Danio rerio

Humans adjust control to initial squat depth in vertical squat jumping

Bobbert, M. F., Casius, L. J. R., Sijpkens, I. W. & Jaspers, R. T. 2008 In : Journal of Applied Physiology. 105, 5, p. 1428-1440

Research output: Contribution to journalArticle

Open Access
File
Posture
Muscles
Musculoskeletal System
Electromyography
Biomechanical Phenomena

Krogh's diffusion coefficient for oxygen in isolated Xenopus skeletal muscle fibers and rat myocardial trabeculae at maximum rates of oxygen consumption

van der Laarse, W. J., des Tombe, A. L., van Beek-Harmsen, B. J., Lee-de Groot, M. B. E. & Jaspers, R. T. 2005 In : Journal of Applied Physiology. 99, p. 2173-80

Research output: Contribution to journalArticle

Skeletal Muscle Fibers
Xenopus
Oxygen Consumption
Oxygen
Muscles