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Lászlo Józsa

Publications and source records attributed to Lászlo Józsa.

3 recordsLinked to original sources
PubMed2003

Mechanical loading regulates the expression of tenascin-C in the myotendinous junction and tendon but does not induce de novo synthesis in the skeletal muscle.

Tenascin-C is a hexabrachion-shaped matricellular protein with a very restricted expression in normal musculoskeletal tissues, but it is expressed abundantly during regenerative processes of these tissues and embryogenesis. To examine the importance of mechanical stress for the regulation of tenascin-C expression in the muscle-tendon unit, the effects of various states of mechanical loading (inactivity by cast-immobilization and three-varying intensities of subsequent re-activity by treadmill running) on the expression of tenascin-C were studied using immunohistochemistry and mRNA in situ hybridization at the different locations of the muscle-tendon unit of the rat gastrocnemius muscle, the Achilles tendon complex. This muscle-tendon unit was selected as the study site, because the contracting activity of the gastrocnemius-soleus muscle complex, and thus the mechanical loading-induced stimulation, is easy to block by cast immobilization. Tenascin-C was expressed abundantly in the normal myotendinous and myofascial junctions, as well as around the cells and the collagen fibers of the Achilles tendon. Tenascin-C expression was not found in the normal skeletal muscle, although it was found in blood vessels within the muscle tissue. Following the removal of the mechanical loading-induced stimulation on the muscle-tendon unit by cast immobilization for 3 weeks, the immonoreactivity of tenascin-C substantially decreased or was completely absent in the regions expressing tenascin-C normally. Restitution of the mechanical loading by removing the cast and allowing free cage activity for 8 weeks resulted in an increase in tenascin-C expression, but it could not restore the expression of tenascin-C to the normal level (in healthy contralateral leg). In response to the application of a more strenuous mechanical loading stimulus after the removal of the cast (after 8 weeks of low- and high-intensity treadmill running), the expression of tenascin-C was markedly increased and reached the level seen in the healthy contralateral limb. Tenascin-C was abundantly expressed in myotendinous and myofascial junctions and in the Achilles tendon, but even the most strenuous mechanical loading (high-intensity treadmill running) could not induce the expression of tenascin-C in the skeletal muscle. This was in spite of the marked immobilization-induced atrophy of the previously immobilized skeletal muscle, which had been subjected to intensive stress during remobilization. mRNA in situ hybridization analysis confirmed the immunohistochemical results for the expression of tenascin-C in the study groups. In summary, this study shows that mechanical loading regulates the expression of tenascin-C in an apparently dose-dependent fashion at sites of the muscle-tendon unit normally expressing tenascin-C but can not induce de novo synthesis of tenascin-C in the skeletal muscle without accompanying injury to the tissue. Our results suggest that tenascin-C provides elasticity in mesenchymal tissues subjected to heavy tensile loading.

Animals↗
PubMed2002

Treatment of tendon disorders. Is there a role for corticosteroid injection?

Tendon injuries and other tendon disorders are a source of major concern in competitive and recreational athletes and in many working conditions requiring repetitive movements. The exact etiology, pathophysiology, and healing mechanisms of the various tendon complaints are, however, only partly known and even origin of pain in the chronic tendon disorders is unknown. Thus, the treatment strategies recommended for tendon complaints vary considerably and the given treatment is frequently based on empirical evidence only. Corticosteroid injections are one of the most commonly used treatments for chronic tendon disorders. Despite their popularity, the biologic basis of their effect and the systematic evidence for their benefits are largely lacking. In addition to suppressing inflammation, the effects of local corticosteroid injections could be mediated through their effect on the connective tissue and adhesions between the tendon and the surrounding peritendinous tissues by inhibiting the production of collagen, other extracellular matrix molecules, and granulation tissue in these sites. Also, if the pain in tendinopathy is a result of stimulation of nociceptors by chemicals released by the damaged, degenerated tendon, corticosteroids might mediate their effect thorough alterations in the release of these noxious chemicals, the behavior of these receptors, or both. Achilles tendinopathy, rotator-cuff tendinopathy, tennis elbow, and trigger finger are among the most frequent tendon problems. There is good evidence, however, strongly supporting the use of local corticosteroid injections in the trigger finger only. This can be to the result of either a true lack of the effect or just a lack of good trials in the other complaints. Intimidation with adverse effects of peritendinous corticosteroid injections is based on case reports only rather than convincing data from controlled clinical studies. In light of the animal studies, corticosteroid injection into tendon substance should be avoided, although the true incidence of side effects after local corticosteroid injection(s) for tendon disorders is unknown. Also, the relevance of the steroid used, the tissue affected, the extent of the tendon problem, the duration of the symptoms, the phase of healing at the time of injections, and the postinjection events remain undetermined. Although a complete tendon rupture with loading after steroid injection has been reported, no reliable proof exists of the deleterious effects of peritendinous injections; conclusions in literature are based mainly on uncontrolled case reports that fail under scientific scrutiny, whereas scientifically rigorous studies have not been performed. An acute tendon disorder often responds favorably to early intervention with conservative treatment modalities. Local corticosteroid injections gives good short-term results in prolonged or subacute cases that do not respond to the conventional conservative treatments. Although corticosteroid injections are one of the most commonly used treatment modalities for chronic tendon disorders, there is an obvious lack of good trials defining the indications for and efficacy of such injections, and subsequently, many of the recommendations for the use of local corticosteroid injections do not rely on sound scientific basis. Thus, there is an obvious need for high-quality basic science studies and controlled clinical trials in examining the effects corticosteroids on various tendon disorders.

Adrenal Cortex Hormones↗