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Michael Kjaer - One of the best experts on this subject based on the ideXlab platform.
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Local administration of insulin-like growth factor-I (IGF-I) stimulates tendon Collagen Synthesis in humans.
Scandinavian journal of medicine & science in sports, 2012Co-Authors: Mette Hansen, Lars Holm, Michael Kjaer, Anders Ploug Boesen, Allan Flyvbjerg, Henning Langberg, Henning Langberg, Michael KjaerAbstract:patellar tendon were performed 24-h apart, respectively. Tendon Collagen fractional Synthesis rate (FSR) was measured by stable isotope technique in the hours after the second injection. Simultaneously, interstitial peritendinous (IGF-I) and [proCollagen type I N-terminal propeptide (PINP)], as a marker for type I Collagen Synthesis, were determined by microdialysis technique. Tendon Collagen FSR and PINP were significantly higher in the IGF-I leg compared with the control leg (P < 0.05). In conclusion, local IGF-I administration can directly enhance tendon Collagen Synthesis both within and around the human tendon tissue.
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gh receptor blocker administration and muscle tendon Collagen Synthesis in humans
Growth Hormone & Igf Research, 2011Co-Authors: Rie Harboe Nielsen, Lars Holm, Simon Doessing, Kazushige Goto, Soren Reitelseder, Jakob Agergaard, Peter Schjerling, Allan Flyvberg, Michael KjaerAbstract:Abstract Context The growth hormone (GH)/insulin-like growth factor-I (IGF-I) axis stimulates Collagen Synthesis in tendon and skeletal muscle, but no studies have investigated the effect of reducing IGF-I on Collagen Synthesis in healthy humans. Objective We hypothesised, that a GH blockade would decrease IGF-I and Collagen Synthesis in the connective tissue of skeletal muscle and tendon. Design The study was randomised and double blinded. Participants 20 healthy young males completed the study. Intervention The participants were randomised to 2 weeks of GH receptor blocker supplementation (pegvisomant, 5 mg/day, n = 9) or placebo (n = 11). Main outcome measures Serum levels of GH, IGF-I and IGF-binding protein 3 (IGFBP-3) were measured before and after pegvisomant/placebo supplementation. Fractional Synthesis rates (FSR) for Collagen and myofibrillar protein were determined with stable isotopes in tendon and muscle, and mRNA for Collagen (COL1A1 and COL3A1) as well as IGF-I isoforms (Ea and Ec) were measured in skeletal muscle. Results Pegvisomant decreased serum IGF-I by 20% (p Conclusion GH receptor blocker administration in healthy humans resulted in a moderate decrease in serum IGF-I. Collagen Synthesis in tendon and skeletal muscle, as well as skeletal muscle IGF-I and Collagen mRNA expression, was unaffected by GH receptor blocker supplementation.
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from mechanical loading to Collagen Synthesis structural changes and function in human tendon
Scandinavian Journal of Medicine & Science in Sports, 2009Co-Authors: Michael Kjaer, Lars Holm, Mette Hansen, Simon Doessing, Henning Langberg, Katja M Heinemeier, Monika L Bayer, M Kongsgaard, Michael Krogsgaard, S P MagnussonAbstract:The adaptive response of connective tissue to loading requires increased Synthesis and turnover of matrix proteins, with special emphasis on Collagen. Collagen formation and degradation in the tendon increases with both acute and chronic loading, and data suggest that a gender difference exists, in that females respond less than males with regard to an increase in Collagen formation after exercise. It is suggested that estrogen may contribute toward a diminished Collagen Synthesis response in females. Conversely, the stimulation of Collagen Synthesis by other growth factors can be shown in both animal and human models where insulin-like growth factor 1 (IGF-I) and transforming growth factor-beta-1 (TGF-beta-1) expression increases to accompany or precede an increase in proCollagen expression and Collagen Synthesis. In humans, it can be demonstrated that an increase in the interstitial concentration of TGF-beta, PGE2, IGF-I plus its binding proteins and interleukin-6 takes place after exercise. The increase in IGF-I expression in tendon includes the isoform that has so far been thought only to exist in skeletal muscle (mechano growth factor). The increase in IGF-I and proCollagen expression showed a similar response whether the tendon was stimulated by concentric, isometric or eccentric muscle contraction, suggesting that strain rather that stress/torque determines the Collagen-Synthesis stimulating response seen with exercise. The adaptation time to chronic loading is longer in tendon tissue compared with contractile elements of skeletal muscle or the heart, and only with very prolonged loading are significant changes in gross dimensions of the tendon observed, suggesting that habitual loading is associated with a robust change in the size and mechanical properties of human tendons. An intimate interplay between mechanical signalling and biochemical changes in the matrix is needed in tendon, such that chemical changes can be converted into adaptations in the morphology, structure and material properties.
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tendon Collagen Synthesis at rest and after exercise in women
Journal of Applied Physiology, 2007Co-Authors: Benjamin F Miller, Mette Hansen, Jens Lykkegaard Olesen, Peter Schwarz, John A Babraj, Kenneth Smith, Michael J Rennie, Michael KjaerAbstract:In general, there is a higher incidence of musculoskeletal injuries during physical activity in women than in men. We hypothesized that in women rates of tendon Collagen Synthesis would be lower th...
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eccentric rehabilitation exercise increases peritendinous type i Collagen Synthesis in humans with achilles tendinosis
Scandinavian Journal of Medicine & Science in Sports, 2006Co-Authors: Henning Langberg, S P Magnusson, H Ellingsgaard, T Madsen, J Jansson, Per Aagaard, Michael KjaerAbstract:It has been shown that 12 weeks of eccentric heavy resistance training can reduce pain in runners suffering from chronic Achilles tendinosis, but the mechanism behind the effectiveness of this treatment is unknown. The present study investigates the local effect of an eccentric training regime on elite soccer players suffering from chronic Achilles tendinosis on the turnover of the peritendinous connective tissue. Twelve elite male soccer players, of whom six suffered from unilateral tendinosis and six were healthy controls, participated in this study. All participants performed 12 weeks of heavy-resistance eccentric training apart from their regular training and soccer activity. Before and after the training period the tissue concentration of indicators of Collagen turnover was measured by the use of the microdialysis technique. After training, Collagen Synthesis was increased in the initially injured tendon (n 5 6; carboxyterminal propeptide of type I Collagen (PICP): pre 3.9 2.5lg/L to post 19.7 5.4lg/L, Po0.05). The Collagen Synthesis was unchanged in healthy tendons in response to training (n 5 6; PICP: pre 8.3 5.2lg/L to post 11.5 5.0lg/L, P40.05). Collagen degradation, measured as carboxyterminal telopeptide region of type I Collagen (ICTP), was not affected by training neither in the injured nor in the healthy tendons. The clinical effect of the 12 weeks of eccentric training was determined by using a standardized loading procedure of the Achilles tendons showing a decrease in pain in all the chronic injured tendons (VAS before 44 9, after 13 9; Po0.05), and all subjects were back playing soccer following the eccentric training regime. The present study demonstrates that chronically injured Achilles tendons respond to 12 weeks of eccentric training by increasing Collagen Synthesis rate. In contrast, the Collagen metabolism in healthy control tendons seems not to be affected by eccentric training. These findings could indicate a relation between Collagen metabolism and recovery from injury in human tendons.
Masahiro Kurosaka - One of the best experts on this subject based on the ideXlab platform.
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mechanical stretching force promotes Collagen Synthesis by cultured cells from human ligamentum flavum via transforming growth factor β1
Journal of Orthopaedic Research, 2002Co-Authors: Tetsuya Nakatani, Takashi Marui, Toshiaki Hitora, Minoru Doita, Kotaro Nishida, Masahiro KurosakaAbstract:Abstract Although mechanical stress as a result of spinal instability is known to cause hypertrophy of the ligamentum flavum resulting in degenerative spinal canal stenosis, the mechanism of the ligament hypertrophy is not well understood. In the present study, we investigated the effect of mechanical stretching force on Collagen Synthesis and transforming growth factor-β1 (TGF-β1) production using ligament cells isolated from human ligamentum flavum in vitro. Ligamentum flavum cells (LFCs) were isolated from human ligamentum flavum obtained from patients who underwent lumbar spine surgery. The LFCs were subjected to a mechanical stretching force using a commercially available stretching device that physically deformed the cells. Collagen Synthesis and TGF-β1 production levels in the LFCs were then examined. Notable increases were observed in the gene expressions of Collagen types I, III, and V in LFCs subjected to mechanical stretching force. The increase in Collagen gene expression of LFCs was inhibited in the presence of anti-TGF-β1 antibodies. Production of TGF-β1 by the LFCs also increased significantly by the mechanical stretching force. Exogenous application of TGF-β1 was confirmed to increase Collagen Synthesis of the LFCs. This data indicated that mechanical stretching force can promote TGF-β1 production by LFCs, resulting in hypertrophy of the ligament.
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mechanical stretching force promotes Collagen Synthesis by cultured cells from human ligamentum flavum via transforming growth factor β1
Journal of Orthopaedic Research, 2002Co-Authors: Tetsuya Nakatani, Takashi Marui, Toshiaki Hitora, Minoru Doita, Kotaro Nishida, Masahiro KurosakaAbstract:Although mechanical stress as a result of spinal instability is known to cause hypertrophy of the ligamentum flavum resulting in degenerative spinal canal stenosis, the mechanism of the ligament hypertrophy is not well understood. In the present study, we investigated the effect of mechanical stretching force on Collagen Synthesis and transforming growth factor-beta1 (TGF-beta1) production using ligament cells isolated from human ligamentum flavum in vitro. Ligamentum flavum cells (LFCs) were isolated from human ligamentum flavum obtained from patients who underwent lumbar spine surgery. The LFCs were subjected to a mechanical stretching force using a commercially available stretching device that physically deformed the cells. Collagen Synthesis and TGF-beta1 production levels in the LFCs were then examined. Notable increases were observed in the gene expressions of Collagen types I, III, and V in LFCs subjected to mechanical stretching force. The increase in Collagen gene expression of LFCs was inhibited in the presence of anti-TGF-beta1 antibodies. Production of TGF-beta1 by the LFCs also increased significantly by the mechanical stretching force. Exogenous application of TGF-beta1 was confirmed to increase Collagen Synthesis of the LFCs. This data indicated that mechanical stretching force can promote TGF-beta1 production by LFCs, resulting in hypertrophy of the ligament.
Tetsuya Nakatani - One of the best experts on this subject based on the ideXlab platform.
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mechanical stretching force promotes Collagen Synthesis by cultured cells from human ligamentum flavum via transforming growth factor β1
Journal of Orthopaedic Research, 2002Co-Authors: Tetsuya Nakatani, Takashi Marui, Toshiaki Hitora, Minoru Doita, Kotaro Nishida, Masahiro KurosakaAbstract:Abstract Although mechanical stress as a result of spinal instability is known to cause hypertrophy of the ligamentum flavum resulting in degenerative spinal canal stenosis, the mechanism of the ligament hypertrophy is not well understood. In the present study, we investigated the effect of mechanical stretching force on Collagen Synthesis and transforming growth factor-β1 (TGF-β1) production using ligament cells isolated from human ligamentum flavum in vitro. Ligamentum flavum cells (LFCs) were isolated from human ligamentum flavum obtained from patients who underwent lumbar spine surgery. The LFCs were subjected to a mechanical stretching force using a commercially available stretching device that physically deformed the cells. Collagen Synthesis and TGF-β1 production levels in the LFCs were then examined. Notable increases were observed in the gene expressions of Collagen types I, III, and V in LFCs subjected to mechanical stretching force. The increase in Collagen gene expression of LFCs was inhibited in the presence of anti-TGF-β1 antibodies. Production of TGF-β1 by the LFCs also increased significantly by the mechanical stretching force. Exogenous application of TGF-β1 was confirmed to increase Collagen Synthesis of the LFCs. This data indicated that mechanical stretching force can promote TGF-β1 production by LFCs, resulting in hypertrophy of the ligament.
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mechanical stretching force promotes Collagen Synthesis by cultured cells from human ligamentum flavum via transforming growth factor β1
Journal of Orthopaedic Research, 2002Co-Authors: Tetsuya Nakatani, Takashi Marui, Toshiaki Hitora, Minoru Doita, Kotaro Nishida, Masahiro KurosakaAbstract:Although mechanical stress as a result of spinal instability is known to cause hypertrophy of the ligamentum flavum resulting in degenerative spinal canal stenosis, the mechanism of the ligament hypertrophy is not well understood. In the present study, we investigated the effect of mechanical stretching force on Collagen Synthesis and transforming growth factor-beta1 (TGF-beta1) production using ligament cells isolated from human ligamentum flavum in vitro. Ligamentum flavum cells (LFCs) were isolated from human ligamentum flavum obtained from patients who underwent lumbar spine surgery. The LFCs were subjected to a mechanical stretching force using a commercially available stretching device that physically deformed the cells. Collagen Synthesis and TGF-beta1 production levels in the LFCs were then examined. Notable increases were observed in the gene expressions of Collagen types I, III, and V in LFCs subjected to mechanical stretching force. The increase in Collagen gene expression of LFCs was inhibited in the presence of anti-TGF-beta1 antibodies. Production of TGF-beta1 by the LFCs also increased significantly by the mechanical stretching force. Exogenous application of TGF-beta1 was confirmed to increase Collagen Synthesis of the LFCs. This data indicated that mechanical stretching force can promote TGF-beta1 production by LFCs, resulting in hypertrophy of the ligament.
Henning Langberg - One of the best experts on this subject based on the ideXlab platform.
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Local administration of insulin-like growth factor-I (IGF-I) stimulates tendon Collagen Synthesis in humans.
Scandinavian journal of medicine & science in sports, 2012Co-Authors: Mette Hansen, Lars Holm, Michael Kjaer, Anders Ploug Boesen, Allan Flyvbjerg, Henning Langberg, Henning Langberg, Michael KjaerAbstract:patellar tendon were performed 24-h apart, respectively. Tendon Collagen fractional Synthesis rate (FSR) was measured by stable isotope technique in the hours after the second injection. Simultaneously, interstitial peritendinous (IGF-I) and [proCollagen type I N-terminal propeptide (PINP)], as a marker for type I Collagen Synthesis, were determined by microdialysis technique. Tendon Collagen FSR and PINP were significantly higher in the IGF-I leg compared with the control leg (P < 0.05). In conclusion, local IGF-I administration can directly enhance tendon Collagen Synthesis both within and around the human tendon tissue.
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from mechanical loading to Collagen Synthesis structural changes and function in human tendon
Scandinavian Journal of Medicine & Science in Sports, 2009Co-Authors: Michael Kjaer, Lars Holm, Mette Hansen, Simon Doessing, Henning Langberg, Katja M Heinemeier, Monika L Bayer, M Kongsgaard, Michael Krogsgaard, S P MagnussonAbstract:The adaptive response of connective tissue to loading requires increased Synthesis and turnover of matrix proteins, with special emphasis on Collagen. Collagen formation and degradation in the tendon increases with both acute and chronic loading, and data suggest that a gender difference exists, in that females respond less than males with regard to an increase in Collagen formation after exercise. It is suggested that estrogen may contribute toward a diminished Collagen Synthesis response in females. Conversely, the stimulation of Collagen Synthesis by other growth factors can be shown in both animal and human models where insulin-like growth factor 1 (IGF-I) and transforming growth factor-beta-1 (TGF-beta-1) expression increases to accompany or precede an increase in proCollagen expression and Collagen Synthesis. In humans, it can be demonstrated that an increase in the interstitial concentration of TGF-beta, PGE2, IGF-I plus its binding proteins and interleukin-6 takes place after exercise. The increase in IGF-I expression in tendon includes the isoform that has so far been thought only to exist in skeletal muscle (mechano growth factor). The increase in IGF-I and proCollagen expression showed a similar response whether the tendon was stimulated by concentric, isometric or eccentric muscle contraction, suggesting that strain rather that stress/torque determines the Collagen-Synthesis stimulating response seen with exercise. The adaptation time to chronic loading is longer in tendon tissue compared with contractile elements of skeletal muscle or the heart, and only with very prolonged loading are significant changes in gross dimensions of the tendon observed, suggesting that habitual loading is associated with a robust change in the size and mechanical properties of human tendons. An intimate interplay between mechanical signalling and biochemical changes in the matrix is needed in tendon, such that chemical changes can be converted into adaptations in the morphology, structure and material properties.
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eccentric rehabilitation exercise increases peritendinous type i Collagen Synthesis in humans with achilles tendinosis
Scandinavian Journal of Medicine & Science in Sports, 2006Co-Authors: Henning Langberg, S P Magnusson, H Ellingsgaard, T Madsen, J Jansson, Per Aagaard, Michael KjaerAbstract:It has been shown that 12 weeks of eccentric heavy resistance training can reduce pain in runners suffering from chronic Achilles tendinosis, but the mechanism behind the effectiveness of this treatment is unknown. The present study investigates the local effect of an eccentric training regime on elite soccer players suffering from chronic Achilles tendinosis on the turnover of the peritendinous connective tissue. Twelve elite male soccer players, of whom six suffered from unilateral tendinosis and six were healthy controls, participated in this study. All participants performed 12 weeks of heavy-resistance eccentric training apart from their regular training and soccer activity. Before and after the training period the tissue concentration of indicators of Collagen turnover was measured by the use of the microdialysis technique. After training, Collagen Synthesis was increased in the initially injured tendon (n 5 6; carboxyterminal propeptide of type I Collagen (PICP): pre 3.9 2.5lg/L to post 19.7 5.4lg/L, Po0.05). The Collagen Synthesis was unchanged in healthy tendons in response to training (n 5 6; PICP: pre 8.3 5.2lg/L to post 11.5 5.0lg/L, P40.05). Collagen degradation, measured as carboxyterminal telopeptide region of type I Collagen (ICTP), was not affected by training neither in the injured nor in the healthy tendons. The clinical effect of the 12 weeks of eccentric training was determined by using a standardized loading procedure of the Achilles tendons showing a decrease in pain in all the chronic injured tendons (VAS before 44 9, after 13 9; Po0.05), and all subjects were back playing soccer following the eccentric training regime. The present study demonstrates that chronically injured Achilles tendons respond to 12 weeks of eccentric training by increasing Collagen Synthesis rate. In contrast, the Collagen metabolism in healthy control tendons seems not to be affected by eccentric training. These findings could indicate a relation between Collagen metabolism and recovery from injury in human tendons.
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eccentric rehabilitation exercise increases peritendinous type i Collagen Synthesis in humans with achilles tendinosis
Scandinavian Journal of Medicine & Science in Sports, 2006Co-Authors: Henning Langberg, S P Magnusson, H Ellingsgaard, T Madsen, J Jansson, Per Aagaard, Michael KjaerAbstract:It has been shown that 12 weeks of eccentric heavy resistance training can reduce pain in runners suffering from chronic Achilles tendinosis, but the mechanism behind the effectiveness of this treatment is unknown. The present study investigates the local effect of an eccentric training regime on elite soccer players suffering from chronic Achilles tendinosis on the turnover of the peritendinous connective tissue. Twelve elite male soccer players, of whom six suffered from unilateral tendinosis and six were healthy controls, participated in this study. All participants performed 12 weeks of heavy-resistance eccentric training apart from their regular training and soccer activity. Before and after the training period the tissue concentration of indicators of Collagen turnover was measured by the use of the microdialysis technique. After training, Collagen Synthesis was increased in the initially injured tendon (n=6; carboxyterminal propeptide of type I Collagen (PICP): pre 3.9+/-2.5 microg/L to post 19.7+/-5.4 microg/L, P 0.05). Collagen degradation, measured as carboxyterminal telopeptide region of type I Collagen (ICTP), was not affected by training neither in the injured nor in the healthy tendons. The clinical effect of the 12 weeks of eccentric training was determined by using a standardized loading procedure of the Achilles tendons showing a decrease in pain in all the chronic injured tendons (VAS before 44+/-9, after 13+/-9; P<0.05), and all subjects were back playing soccer following the eccentric training regime. The present study demonstrates that chronically injured Achilles tendons respond to 12 weeks of eccentric training by increasing Collagen Synthesis rate. In contrast, the Collagen metabolism in healthy control tendons seems not to be affected by eccentric training. These findings could indicate a relation between Collagen metabolism and recovery from injury in human tendons.
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type i Collagen Synthesis and degradation in peritendinous tissue after exercise determined by microdialysis in humans
The Journal of Physiology, 1999Co-Authors: Henning Langberg, Michael Kjaer, Dorthe Skovgaard, Lars Jelstrup Petersen, Jens Bulow, Henning Langberg, Michael KjaerAbstract:Physical activity is known to increase type I Collagen Synthesis measured as the concentration of biomarkers in plasma. By the use of microdialysis catheters with a very high molecular mass cut-off value (3000 kDa) we aimed to determine local type I Collagen Synthesis and degradation in the peritendinous region by measuring interstitial concentrations of a Collagen propeptide (PICP; 100 kDa) and a Collagen degradation product (ICTP; 9 kDa) as well as an inflammatory mediator (PGE2). Seven trained human runners were studied before and after (2 and 72 h) 3 h of running (36 km). Two microdialysis catheters were placed in the peritendinous space ventral to the Achilles' tendon under ultrasound guidance and perfused with a Ringer-acetate solution containing 3H-labelled human type IV Collagen and [15-3H(N)]PGE2 for in vivo recovery determination. Relative recovery was 37–59% (range of the s.e.m. values) for both radioactively labelled substances. PICP concentration decreased in both interstitial peritendinous tissue and arterial blood immediately after exercise, but rose 3-fold from basal 72 h after exercise in the peritendinous tissue (55 ± 10 μg l−1, mean ± s.e.m. (rest) to 165 ± 40 μg l−1 (72 h), P < 0·05) and by 25% in circulating blood (160 ± 10 μg l−1 (rest) to 200 ± 12 μg l−1 (72 h), P < 0·05). ICTP concentration did not change in blood, but decreased transiently in tendon-related tissue during early recovery after exercise only. PGE2 concentration increased in blood during running, and returned to baseline in the recovery period, whereas interstitial PGE2 concentration was elevated in the early recovery phase. The findings of the present study indicate that acute exercise induces increased formation of type I Collagen in peritendinous tissue as determined with microdialysis and using dialysate fibre with a very high molecular mass cut-off. This suggests an adaptation to acute physical loading also in non-bone-related Collagen in humans. Exercise is known to improve physical properties, e.g. maximal tensile strength, as well as mass and turnover of Collagen in bone, ligaments and tendons (Tipton et al. 1975; Kiiskinen, 1977; Suominen et al. 1980; Woo et al. 1982; Michna & Hartmann, 1989). Nevertheless, the specific mechanisms by which these tissues detect and convert mechanical loading into physical properties of the relevant tissue is still not thoroughly understood (Simonsen et al. 1995), but it has been suggested that local factors such as prostaglandins and cytokines participate in the remodelling process of Collagen (Huffer, 1988). Type I Collagen, the dominant connective tissue protein in tendon, ligaments and bone (Risteli et al. 1995), has been considered to have a relatively low tissue turnover (Prockop et al. 1979). However, recent studies have demonstrated that the peritendinous connective tissue exerts more metabolic and inflammatory activity than hitherto thought (Langberg et al. 1999) and is influenced by heredity, nerve supply, physical activity, and systemic factors such as various regulating hormones and local factors like cytokines, prostaglandins and neuropeptides (Huffer, 1988; Goldring & Goldring, 1990; Banes et al. 1995; O'Brien, 1997). During recent years the development of assays for determination of Collagen conversion has allowed for a more detailed study of Collagen turnover (Melkko et al. 1990, 1996; Eriksen et al. 1995). On this background changes in type I Collagen Synthesis and degradation have been studied by measuring the carboxy-terminal propeptide of type I Collagen (PICP) as a marker for Collagen Synthesis and the carboxy-terminal telopeptide region of type I Collagen (ICTP) as an indicator of Collagen breakdown after short and prolonged single bouts of exercise (Takala et al. 1989; Virtanen et al. 1993; Salvesen et al. 1994; Kristoffersson et al. 1995; Thorsen et al. 1996a; Ashizawa et al. 1998) and after weeks of training (Price et al. 1995; Eliakim et al. 1997; Hupli et al. 1997). These studies have shown that a single short bout of exercise does not have the ability to change Collagen Synthesis and degradation in contrast to prolonged exercise or weeks of training. However, all these studies have measured the levels of PICP and ICTP in serum, making it difficult to detect the location of the specific type of tissue in which changes in Synthesis and breakdown are taking place. It has been suggested that prostaglandin is involved in the conversion of mechanical force into Collagen formation in bone (Thorsen et al. 1996b) and thus in the present study PGE2 was measured to investigate any potential increase in interstitial PGE2 concentration and its coupling to changes in Collagen Synthesis. The microdialysis technique allows for in vivo monitoring of biochemical substances in local tissue during various forms of intervention (Delgado et al. 1972; Ungerstedt & Pycock, 1974). The method has recently been applied to the peritendinous space around the Achilles' tendon, measuring low molecular mass substances such as glucose, lactate, glycerol, prostaglandin (PGE2) and thromboxane (TXB2) both at rest and during intermittent static exercise (Langberg et al. 1999). It has, however, not been possible so far to use microdialysis for detection of interstitial concentrations of large molecules (> 20 kDa) as the maximal molecular mass cut-off of the microdialysis membranes commercially available was 20 kDa. In the present study we describe, to our knowledge for the first time, the use of microdialysis probes with a high molecular mass cut-off (3000 kDa), allowing for large molecules involved in type I Collagen turnover such as PICP (100 kDa) and ICTP (9 kDa) to be determined in a specific region in situ. The microdialysis method was used to monitor changes in local type I Collagen turnover in the connective tissue of the Achilles' peritendinous space after prolonged running in trained individuals.
Ming Hong Chen - One of the best experts on this subject based on the ideXlab platform.
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second messengers mediating the proliferation and Collagen Synthesis of tenocytes induced by low level laser irradiation
Lasers in Medical Science, 2015Co-Authors: Meihsiu Chen, Yunchien Huang, Juisheng Sun, Yuanhung Chao, Ming Hong ChenAbstract:For decades, low-level laser therapy (LLLT) has widespread applications in tendon-related injuries. Although the therapeutic effect of LLLT could be explained by photostimulation of target tissue and cells, how tenocytes sense photonic energy and convert them into cascades of cellular and molecular events is still not well understood. This study was designed to elucidate the effects of LLLT on cell proliferation and Collagen Synthesis by examining the associated second messengers including ATP, Ca2+, and nitric oxide using rat Achilles tenocytes. Moreover, proliferating cell nuclear antigen (PCNA) and transforming growth factor-β1 (TGF-β1) related to cell proliferation and matrix metabolism were also studied. The results showed that 904 nm GaAs laser of 1 J/cm2 could significantly increase the MTT activity and Collagen Synthesis of tenocytes. Second messengers including ATP and intracellular Ca2+ were increased after laser treatment. Quantitative PCR analysis of tenocytes treated with laser revealed up-regulated expression of PCNA, type I Collagen, and TGF-β1. Besides, laser-induced TGF-β1 expression was significantly inhibited by extracellular signal-regulated kinase (ERK) specific inhibitor (PD98059). The findings suggested that LLLT stimulated ATP production and increased intracellular calcium concentration. Directly or indirectly via production of TGF-β1, these second messengers mediated the proliferation of tenocytes and Synthesis of Collagen.