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Goering
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Llego la hora de acabar el blah blah blah con pruebas CIENTIFICAS, que es lo único que vale, después quiero que me pongas tus pruebas cientificas, aqui van los estudios, este primero con músculos DENERVADOS (sin nervios) en donde se demuestra que el músculo puede crecer bajo esas condiciones, y que el sistema nervioso no es el que juega el rol principal (de nuevo repito, no es que pienso que no juegue un rol, sino que NO es el principal, ya que ironbarbarian tiende a mal interpretar lo que digo):
Pflugers Arch 1999 Dec;439(1-2):52-5 Related Articles, Books, LinkOut
Passive stretch modulates denervation induced alterations in skeletal muscle myosin heavy chain mRNA levels.
Loughna PT, Morgan MJ.
Department of Veterinary Basic Sciences, The Royal Veterinary College, London University, UK. [email protected]
The effect of denervation and denervation combined with immobilisation in either the shortened or lengthened position (passive stretch) upon myosin heavy chain (MyHC) mRNA levels was examined in three rat hind-limb muscles with differing phenotypes. Denervation alone caused a reduction in type I and type IIa MyHC transcripts in all three muscles. In contrast denervation caused a 72% increase in type IIb in the slow postural soleus muscle only which was prevented by immobilisation in the lengthened position. In the same muscle passive stretch also significantly retarded the effects of denervation upon the type I transcript (from 38% below control levels to 24% below) and type IIa transcript (from 59% to 32% below control levels). The levels of both type I and IIa transcripts, in the fast phasic plantaris muscle, were both unaffected by stretch combined with denervation when compared to denervation alone. In the mixed gastrocnemius muscle stretch affected the level of the type I but not the type IIa transcript. These data suggest that passive stretch can modulate MyHC gene expression independently of innervation but that it does so in a muscle-specific manner.
PMID: 10651000 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------
En este segundo estudio se habla también de músculos denervados:
Med Sci Sports 1975 Fall;7(3):185-98 Related Articles, Books
Mechanism of work-induced hypertrophy of skeletal muscle.
Goldberg AL, Etlinger JD, Goldspink DF, Jablecki C.
Skeletal muscle can undergo rapid growth in response to a sudden increase in work load. For example, the rat soleus muscle increases in weight by 40% within six days after the tendon of the synergistic gastrocnemius is sectioned. Such growth of the overworked muscle involves an enlargement of muscle fibers and occasional longitudinal splitting. Hypertrophy leads to greater maximal tension development, although decreased contraction time and reduced contractility have also been reported. Unlike normal developmental growth, work-induced hypertrophy can be induced in hypophysectomized or diabetic animals. This process thus appears independent of growth hormone and insulin as well as testosterone and thyroid hormones. Hypertrophy of the soleus can also be induced in fasting animals, in which there is a generalized muscle wasting. Thus muscular activity takes precedence over endocrine influences on muscle size. The increase in muscle weight reflects an increase in protein, especially sarcoplasmic protein, and results from greater protein synthesis and reduced protein breakdown. Within several hours after operation, the hypertrophying soleus shows more rapid uptake of certain amino acids and synthesis of phosphatidyl-inositol. By 8 hours, protein synthesis is enhanced. RNA synthesis also increases, and hypertrophy can be prevented with actinomycin D. Nuclear DNA synthesis also increases on the second day after operation and leads to a greater DNA content. The significance of the increased RNA and DNA synthesis is not clear, since most of it occurs in interstitial and satellite cells. The proliferation of the non-muscle cells seems linked to the growth of the muscle fibers; in addition, factors causing muscle atrophy (e.g. denervation) decrease DNA synthesis by such cells. In order to define more precisely the early events in hypertrophy, the effects of contractile activity were studied in rat muscles in vitro. Electrical stimulation enhanced active transport of certain amino acids within an hour, and the magnitude of this effect depended on the amount of contractile activity. Stimulation or passive stretch of the soleus or diaphragm also retarded protein degradation. Presumably these effects of mechanical activity contribute to the changes occuring during hypertrophy in vivo. However, under the same conditions, or even after more prolonged stimulation, no change in rates of protein synthesis was detected. These findings with passive tension in vitro are particularly interesting, since passive stretch has been reported to retard atrophy or to induce hypertrophy of denervated muscle in vivo. It is suggested that increased tension development (either passive or active) is the critical event in initiating compensatory growth.
PMID: 128681 [PubMed - indexed for MEDLINE]
--------------------------------------------------
En este tercer estudio, se demuestra que el estiramiento induce hipertrofia muscular:
Genomics 2001 Apr 1;73(1):38-49 Related Articles, Nucleotide, Protein, Books, LinkOut
Erratum in:
* Genomics 2001 Jun 1;74(2):251
[Click here to read]
Identification of Serhl, a new member of the serine hydrolase family induced by passive stretch of skeletal muscle in vivo.
Sadusky TJ, Kemp TJ, Simon M, Carey N, Coulton GR.
Molecular Pathology, Vascular Surgery, Division of Surgery and Anaesthetics, Imperial College of Science, Technology and Medicine, Sir Alexander Fleming Building, South Kensington, London, SW7 2AZ, UK.
In response to extended periods of stretch, skeletal muscle typically exhibits cell hypertrophy associated with sustained increases in mRNA and protein synthesis. Several soluble hypertrophic agonists have been identified, yet relatively little is known as to how mechanical load is converted into intracellular signals regulating gene expression or how increased cell size is maintained. In skeletal muscle, hypertrophy is generally regarded as a beneficial adaptive response to increased workload. In some cases, however, hypertrophy can be detrimental as seen in long-term cardiac hypertrophy. Skeletal muscle wasting (atrophy) is a feature of both inherited and acquired muscle disease and normal aging. Elucidating the molecular regulation of cell size is a fundamental step toward comprehending the complex molecular systems underlying muscle hypertrophy and atrophy. Subtractive hybridization between passively stretched and control murine skeletal muscle tissue identified an mRNA that undergoes increased expression in response to passive stretch. Encoded within the mRNA is an open reading frame of 311 amino acids containing a highly conserved type 1 peroxisomal targeting signal and a serine lipase active center. The sequence shows identity to a family of serine hydrolases and thus is named serine hydrolase-like (Serhl). The predicted three-dimensional structure displays a core alpha/beta-hydrolase fold and catalytic triad characteristic of several hydrolytic enzymes. Endogenous Serhl protein immunolocalizes to perinuclear vesicles as does Serhl-FLAG fusion protein transiently expressed in muscle cells in vitro. Overexpression of Serhl-FLAG has no effect on muscle cell phenotype in vitro. Serhl's expression patterns and its response to passive stretch suggest that it may play a role in normal peroxisome function and skeletal muscle growth in response to mechanical stimuli. Copyright 2001 Academic Press.
PMID: 11352564 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------
En este cuarto estudio se demuestra como el estiramiento evita la pérdida muscular:
Acta Physiol Scand 2001 Jun;172(2):131-40 Related Articles, Books, LinkOut
[Click here to read]
Regulation of synthesis of fibrillar collagens in rat skeletal muscle during immobilization in shortened and lengthened positions.
Ahtikoski AM, Koskinen SO, Virtanen P, Kovanen V, Takala TE.
Department of Biology of Physical Activity, University of Jyvaskyla, Jyvaskyla, Finland.
Immobilization has been shown to cause muscle atrophy and decreased total collagen synthesis in skeletal muscle. These changes can be counteracted by stretch. The purpose of this study was to find out the early effects of immobilization in shortened and lengthened positions on expression of type I and III collagen at pre- and post-translational level. The mRNA levels of type I and III collagen, prolyl 4-hydroxylase activity, total collagen concentration and the proportions of type I and III collagens were analysed in soleus (SOL), gastrocnemius (GM), extensor digitorum longus and tibialis anterior (TA) muscles during immobilization in shortened and lengthened positions for 1, 3 and 7 days. The mRNA levels for type I and III collagens decreased during 3-7 days in all muscles, except TA. In shortened GM and SOL, the mRNA level of type I collagen was lower than in the corresponding lengthened muscles. Prolyl 4-hydroxylase activity decreased in all muscles during 3-7 days. The activity in shortened GM was 30-37% lower than in the lengthened one during 3-7 days. Total collagen concentration and proportions of type I and III collagen showed no change during the 7-day immobilization period. The present study suggests that immobilization results in rapid down-regulation of total muscular collagen synthesis and that the timing and degree is roughly similar in type I and III collagens. Stretch seems to partially counteract these effects. Immobilization effect and the partially preventive effect of stretch on down-regulation of gene expression of prolyl 4-hydroxylase and fibrillar collagens during immobilization seems to be greater in weight-bearing SOL and GM than ankle joint dorsiflexors.
PMID: 11442453 [PubMed - indexed for MEDLINE]
----------------------------------------------------------------
En este quinto estudio se explica como el estiramiento induce los factores regulatorios del crecimiento:
J Muscle Res Cell Motil 1999 May;20(4):395-402 Related Articles, Books, LinkOut
Prolonged passive stretch of rat soleus muscle provokes an increase in the mRNA levels of the muscle regulatory factors distributed along the entire length of the fibers.
Zador E, Dux L, Wuytack F.
Inst. Biochem., Albert Szent-Gyorgyi Med. Univ., Szeged, Hungary. [email protected]
The mRNA levels of the adult and the neonatal sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPases (SERCA1a and SERCA1b, respectively) and those of the muscle regulatory factors (MRFs: myoD, myf-5, myogenin, MRF4) have been assessed by RT PCR in rat soleus muscles immobilized for 3 days in an extended position (passive stretch). The transcript level of the fast type SERCA1a Ca(2+)-transport ATPase decreased to half of its normal value, whereas that of neonatal SERCA1b isoform increased 5-fold above control in stretched muscles. Immunostaining of muscle cross sections showed that the fraction of fibers expressing the SERCA1a protein was decreased evenly along the length of the stretched muscles indicating that a transformation occurred of fast fibers to slow ones. The mRNA levels of MRFs were elevated 3- to 6-fold above the normal level and were distributed evenly along the length of the stretched muscles. However in the controls these transcripts were more abundant at both ends of the muscle. The stretch increased the level of myoD and immunocytochemistry showed the expression of myoD protein in a number of nuclei of the stretched muscles whereas it was practically undetectable by this method in the control muscles. Western blotting did not indicate a significant stretch-induced increase in the level of the myogenin protein, in spite of the fact that immunocytochemistry tended to show more myogenin-positive nuclei in stretched muscles as compared to the controls. These data indicate that after 3 days of passive stretch the central and the terminal parts of the soleus muscle adapt similarly by increasing the levels of the MRFs, by decreasing the overall levels of the fast SERCA1-type of ATPase and by partially re-establishing a neonatal mode of alternative SERCA1 transcript splicing resulting in an increased SERCA1b/1a ratio.
PMID: 10531620 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------
Bueno, llego la hora de la camita
Saludos.
Pflugers Arch 1999 Dec;439(1-2):52-5 Related Articles, Books, LinkOut
Passive stretch modulates denervation induced alterations in skeletal muscle myosin heavy chain mRNA levels.
Loughna PT, Morgan MJ.
Department of Veterinary Basic Sciences, The Royal Veterinary College, London University, UK. [email protected]
The effect of denervation and denervation combined with immobilisation in either the shortened or lengthened position (passive stretch) upon myosin heavy chain (MyHC) mRNA levels was examined in three rat hind-limb muscles with differing phenotypes. Denervation alone caused a reduction in type I and type IIa MyHC transcripts in all three muscles. In contrast denervation caused a 72% increase in type IIb in the slow postural soleus muscle only which was prevented by immobilisation in the lengthened position. In the same muscle passive stretch also significantly retarded the effects of denervation upon the type I transcript (from 38% below control levels to 24% below) and type IIa transcript (from 59% to 32% below control levels). The levels of both type I and IIa transcripts, in the fast phasic plantaris muscle, were both unaffected by stretch combined with denervation when compared to denervation alone. In the mixed gastrocnemius muscle stretch affected the level of the type I but not the type IIa transcript. These data suggest that passive stretch can modulate MyHC gene expression independently of innervation but that it does so in a muscle-specific manner.
PMID: 10651000 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------
En este segundo estudio se habla también de músculos denervados:
Med Sci Sports 1975 Fall;7(3):185-98 Related Articles, Books
Mechanism of work-induced hypertrophy of skeletal muscle.
Goldberg AL, Etlinger JD, Goldspink DF, Jablecki C.
Skeletal muscle can undergo rapid growth in response to a sudden increase in work load. For example, the rat soleus muscle increases in weight by 40% within six days after the tendon of the synergistic gastrocnemius is sectioned. Such growth of the overworked muscle involves an enlargement of muscle fibers and occasional longitudinal splitting. Hypertrophy leads to greater maximal tension development, although decreased contraction time and reduced contractility have also been reported. Unlike normal developmental growth, work-induced hypertrophy can be induced in hypophysectomized or diabetic animals. This process thus appears independent of growth hormone and insulin as well as testosterone and thyroid hormones. Hypertrophy of the soleus can also be induced in fasting animals, in which there is a generalized muscle wasting. Thus muscular activity takes precedence over endocrine influences on muscle size. The increase in muscle weight reflects an increase in protein, especially sarcoplasmic protein, and results from greater protein synthesis and reduced protein breakdown. Within several hours after operation, the hypertrophying soleus shows more rapid uptake of certain amino acids and synthesis of phosphatidyl-inositol. By 8 hours, protein synthesis is enhanced. RNA synthesis also increases, and hypertrophy can be prevented with actinomycin D. Nuclear DNA synthesis also increases on the second day after operation and leads to a greater DNA content. The significance of the increased RNA and DNA synthesis is not clear, since most of it occurs in interstitial and satellite cells. The proliferation of the non-muscle cells seems linked to the growth of the muscle fibers; in addition, factors causing muscle atrophy (e.g. denervation) decrease DNA synthesis by such cells. In order to define more precisely the early events in hypertrophy, the effects of contractile activity were studied in rat muscles in vitro. Electrical stimulation enhanced active transport of certain amino acids within an hour, and the magnitude of this effect depended on the amount of contractile activity. Stimulation or passive stretch of the soleus or diaphragm also retarded protein degradation. Presumably these effects of mechanical activity contribute to the changes occuring during hypertrophy in vivo. However, under the same conditions, or even after more prolonged stimulation, no change in rates of protein synthesis was detected. These findings with passive tension in vitro are particularly interesting, since passive stretch has been reported to retard atrophy or to induce hypertrophy of denervated muscle in vivo. It is suggested that increased tension development (either passive or active) is the critical event in initiating compensatory growth.
PMID: 128681 [PubMed - indexed for MEDLINE]
--------------------------------------------------
En este tercer estudio, se demuestra que el estiramiento induce hipertrofia muscular:
Genomics 2001 Apr 1;73(1):38-49 Related Articles, Nucleotide, Protein, Books, LinkOut
Erratum in:
* Genomics 2001 Jun 1;74(2):251
[Click here to read]
Identification of Serhl, a new member of the serine hydrolase family induced by passive stretch of skeletal muscle in vivo.
Sadusky TJ, Kemp TJ, Simon M, Carey N, Coulton GR.
Molecular Pathology, Vascular Surgery, Division of Surgery and Anaesthetics, Imperial College of Science, Technology and Medicine, Sir Alexander Fleming Building, South Kensington, London, SW7 2AZ, UK.
In response to extended periods of stretch, skeletal muscle typically exhibits cell hypertrophy associated with sustained increases in mRNA and protein synthesis. Several soluble hypertrophic agonists have been identified, yet relatively little is known as to how mechanical load is converted into intracellular signals regulating gene expression or how increased cell size is maintained. In skeletal muscle, hypertrophy is generally regarded as a beneficial adaptive response to increased workload. In some cases, however, hypertrophy can be detrimental as seen in long-term cardiac hypertrophy. Skeletal muscle wasting (atrophy) is a feature of both inherited and acquired muscle disease and normal aging. Elucidating the molecular regulation of cell size is a fundamental step toward comprehending the complex molecular systems underlying muscle hypertrophy and atrophy. Subtractive hybridization between passively stretched and control murine skeletal muscle tissue identified an mRNA that undergoes increased expression in response to passive stretch. Encoded within the mRNA is an open reading frame of 311 amino acids containing a highly conserved type 1 peroxisomal targeting signal and a serine lipase active center. The sequence shows identity to a family of serine hydrolases and thus is named serine hydrolase-like (Serhl). The predicted three-dimensional structure displays a core alpha/beta-hydrolase fold and catalytic triad characteristic of several hydrolytic enzymes. Endogenous Serhl protein immunolocalizes to perinuclear vesicles as does Serhl-FLAG fusion protein transiently expressed in muscle cells in vitro. Overexpression of Serhl-FLAG has no effect on muscle cell phenotype in vitro. Serhl's expression patterns and its response to passive stretch suggest that it may play a role in normal peroxisome function and skeletal muscle growth in response to mechanical stimuli. Copyright 2001 Academic Press.
PMID: 11352564 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------
En este cuarto estudio se demuestra como el estiramiento evita la pérdida muscular:
Acta Physiol Scand 2001 Jun;172(2):131-40 Related Articles, Books, LinkOut
[Click here to read]
Regulation of synthesis of fibrillar collagens in rat skeletal muscle during immobilization in shortened and lengthened positions.
Ahtikoski AM, Koskinen SO, Virtanen P, Kovanen V, Takala TE.
Department of Biology of Physical Activity, University of Jyvaskyla, Jyvaskyla, Finland.
Immobilization has been shown to cause muscle atrophy and decreased total collagen synthesis in skeletal muscle. These changes can be counteracted by stretch. The purpose of this study was to find out the early effects of immobilization in shortened and lengthened positions on expression of type I and III collagen at pre- and post-translational level. The mRNA levels of type I and III collagen, prolyl 4-hydroxylase activity, total collagen concentration and the proportions of type I and III collagens were analysed in soleus (SOL), gastrocnemius (GM), extensor digitorum longus and tibialis anterior (TA) muscles during immobilization in shortened and lengthened positions for 1, 3 and 7 days. The mRNA levels for type I and III collagens decreased during 3-7 days in all muscles, except TA. In shortened GM and SOL, the mRNA level of type I collagen was lower than in the corresponding lengthened muscles. Prolyl 4-hydroxylase activity decreased in all muscles during 3-7 days. The activity in shortened GM was 30-37% lower than in the lengthened one during 3-7 days. Total collagen concentration and proportions of type I and III collagen showed no change during the 7-day immobilization period. The present study suggests that immobilization results in rapid down-regulation of total muscular collagen synthesis and that the timing and degree is roughly similar in type I and III collagens. Stretch seems to partially counteract these effects. Immobilization effect and the partially preventive effect of stretch on down-regulation of gene expression of prolyl 4-hydroxylase and fibrillar collagens during immobilization seems to be greater in weight-bearing SOL and GM than ankle joint dorsiflexors.
PMID: 11442453 [PubMed - indexed for MEDLINE]
----------------------------------------------------------------
En este quinto estudio se explica como el estiramiento induce los factores regulatorios del crecimiento:
J Muscle Res Cell Motil 1999 May;20(4):395-402 Related Articles, Books, LinkOut
Prolonged passive stretch of rat soleus muscle provokes an increase in the mRNA levels of the muscle regulatory factors distributed along the entire length of the fibers.
Zador E, Dux L, Wuytack F.
Inst. Biochem., Albert Szent-Gyorgyi Med. Univ., Szeged, Hungary. [email protected]
The mRNA levels of the adult and the neonatal sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPases (SERCA1a and SERCA1b, respectively) and those of the muscle regulatory factors (MRFs: myoD, myf-5, myogenin, MRF4) have been assessed by RT PCR in rat soleus muscles immobilized for 3 days in an extended position (passive stretch). The transcript level of the fast type SERCA1a Ca(2+)-transport ATPase decreased to half of its normal value, whereas that of neonatal SERCA1b isoform increased 5-fold above control in stretched muscles. Immunostaining of muscle cross sections showed that the fraction of fibers expressing the SERCA1a protein was decreased evenly along the length of the stretched muscles indicating that a transformation occurred of fast fibers to slow ones. The mRNA levels of MRFs were elevated 3- to 6-fold above the normal level and were distributed evenly along the length of the stretched muscles. However in the controls these transcripts were more abundant at both ends of the muscle. The stretch increased the level of myoD and immunocytochemistry showed the expression of myoD protein in a number of nuclei of the stretched muscles whereas it was practically undetectable by this method in the control muscles. Western blotting did not indicate a significant stretch-induced increase in the level of the myogenin protein, in spite of the fact that immunocytochemistry tended to show more myogenin-positive nuclei in stretched muscles as compared to the controls. These data indicate that after 3 days of passive stretch the central and the terminal parts of the soleus muscle adapt similarly by increasing the levels of the MRFs, by decreasing the overall levels of the fast SERCA1-type of ATPase and by partially re-establishing a neonatal mode of alternative SERCA1 transcript splicing resulting in an increased SERCA1b/1a ratio.
PMID: 10531620 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------
Bueno, llego la hora de la camita
Saludos.