Immobilization and therapeutic passive stretching generate thickening and increase the expression of laminin and dystrophin in skeletal muscle

Extracellular matrix and costamere proteins transmit the concentric, isometric, and eccentric forces produced by active muscle contraction. The expression of these proteins after application of passive tension stimuli to muscle remains unknown. This study investigated the expression of laminin and dystrophin in the soleus muscle of rats immobilized with the right ankle in plantar flexion for 10 days and subsequent remobilization, either by isolated free movement in a cage or associated with passive stretching for up to 10 days. The intensity of the macrophage response was also evaluated. One hundred and twenty-eight female Wistar rats were divided into 8 groups: free for 10 days; immobilized for 10 days; immobilized/free for 1, 3, or 10 days; or immobilized/stretched/free for 1, 3, or 10 days. After the experimental procedures, muscle tissue was processed for immunofluorescence (dystrophin/laminin/CD68) and Western blot analysis (dystrophin/laminin). Immobilization increased the expression of dystrophin and laminin but did not alter the number of macrophages in the muscle. In the stretched muscle groups, there was an increase in dystrophin and the number of macrophages after 3 days compared with the other groups; dystrophin showed a discontinuous labeling pattern, and laminin was found in the intracellular space. The amount of laminin was increased in the muscles treated by immobilization followed by free movement for 10 days. In the initial stages of postimmobilization (1 and 3 days), an exacerbated macrophage response and an increase of dystrophin suggested that the therapeutic stretching technique induced additional stress in the muscle fibers and costameres.

Immobilization and therapeutic passive stretching generate thickening and increase the expression of laminin and dystrophin in skeletal muscle.

Extracellular matrix and costamere proteins transmit the concentric, isometric, and eccentric forces produced by active muscle contraction. The expression of these proteins after application of passive tension stimuli to muscle remains unknown. This study investigated the expression of laminin and dystrophin in the soleus muscle of rats immobilized with the right ankle in plantar flexion for 10 days and subsequent remobilization, either by isolated free movement in a cage or associated with passive stretching for up to 10 days. The intensity of the macrophage response was also evaluated. One hundred and twenty-eight female Wistar rats were divided into 8 groups: free for 10 days; immobilized for 10 days; immobilized/free for 1, 3, or 10 days; or immobilized/stretched/free for 1, 3, or 10 days. After the experimental procedures, muscle tissue was processed for immunofluorescence (dystrophin/laminin/CD68) and Western blot analysis (dystrophin/laminin). Immobilization increased the expression of dystrophin and laminin but did not alter the number of macrophages in the muscle. In the stretched muscle groups, there was an increase in dystrophin and the number of macrophages after 3 days compared with the other groups; dystrophin showed a discontinuous labeling pattern, and laminin was found in the intracellular space. The amount of laminin was increased in the muscles treated by immobilization followed by free movement for 10 days. In the initial stages of postimmobilization (1 and 3 days), an exacerbated macrophage response and an increase of dystrophin suggested that the therapeutic stretching technique induced additional stress in the muscle fibers and costameres.

Marcadores de fibrogénesis hepática en pacientes alcohólicos / Hepatic fibrogenesis markers in alcoholic patients

Serum P-III-P and laminim levels were measured in asymptomatic alcoholics during detoxication treatment. Liver biopsies were obtained, in order to detect liver damage, which was graded with a numeric score, considering values over 6 as severe damage. Serum fibrogenesis markers were also measured in a group of decompensated alcoholic cirrhotics. P-III-P levels were significantly higher in cirrhotic patients compared to alcoholics with or without liver damage and to normal controls. Laminin was not different between groups. P-III-P did not correlate with histological score in asymptomatic patients. In this study P-III-P and P1 laminin were not usefull discriminators of severe liver damage among asymptomatic alcoholics; their levels were found to rises significantly only when liver disease has become clinically evident

Limb bud mesenchyme permits seminiferous cord formation in the mouse fetal testis but subsequent testosterone output is markedly affected by the sex of the donor stromal tissue.

Mesonephric stromal cells have previously been shown to migrate into the genital ridge and to be necessary for seminiferous cord formation in organ culture. Here, we asked whether there is a specific requirement for mesonephric stromal cells or whether another source of mesonephric stromal cells can be substituted. Hindlimb buds were immersed in a vital stain and then grafted to male gonad primordia and cultured for 96 hr. Immunocytochemical staining of laminin was used to identify seminiferous cord formation. For Sertoli and Leydig cell differentiation, müllerian inhibiting substance and delta 5-3 beta-hydroxysteroid dehydrogenase were used, respectively. Testosterone secreted into the culture medium was assessed by radioimmunoanalysis. It was found that hindlimb stromal cells, like mesonephric stromal cells, migrate into the genital ridge and allow seminiferous cord formation. These results indicate that mesonephric stromal cells are not specifically required for seminiferous cord formation in the mouse fetal gonad. Furthermore, although Sertoli and Leydig cells differentiate in the gonads grafted to hindlimbs from either male or female embryos, testosterone production was considerably higher with hindlimbs from males. A similar stromal sex effect on subsequent testosterone output was also seen with mesonephric stromal cells.

Estudos envolvendo uma família de glicoproteínas (Tc-85) da superfície do protozoário flagelado Trypanosoma cruzi / Studies involving a glycoprotein family (Tc-85) of the surface of Trypanosoma cruzi flagellate protozoan

Laminina-1 liga-se especificamente a formas tripomastigotas de Trypanosoma cruzi e anticorpos gerados contra laminina-1 inibem entre 62-75 por cento a interiorizaçäo do T. cruzi em células LLC-MK2, sugerindo a participaçäo desta glicoproteína no processo de adesäo/interiorizaçäo do parasita em células näo-fagocíticas profissionais. Uma glicoproteína de peso molecular aparente de 85 kDa, denominada LBG (Laminin Binding Glycoprotein), foi identificada em formas tripomastigotas como o principal ligante de laminina-1 no Trypanosoma cruzi, sendo a interaçäo laminina-LBG independente dos carboidratos de ambas as moléculas e mediada preferencialmente pelo fragmento E8 da laminina-1. A LBG é reconhecida por um anticorpo monoclonal (H1A10), previamente descrito na literatura...

Identification and characterization of highly conserved antigenic determinants in the laminin molecule.

1. Fragments P1 and E8, the result of two different enzymatic digestions of the laminin molecule, represent interaction sites of laminin with specific cell receptors. By using negative and positive affinity purification of a rabbit antiserum against mouse laminin we have generated antibodies to these two fragments. 2. Antibodies against P1 were able to immunoprecipitate fragment E8 from elastase-digested laminin. By liquid phase competition experiments we demonstrated that the epitopes shared by P1 and E8 are a minor portion of the antigenic determinants of P1. When we checked for the presence of these shared epitopes in the human laminin molecule, they were the major fraction of the interspecies antigenic conservation. 3. A similar approach using polyclonal antibodies against human laminin has confirmed these results. 4. The shared epitopes present in both mouse and human laminin molecules seem to be spatially determined, because antibodies against these sites did not bind to fully denatured laminin. 5. Since human and mouse laminin bind to cell receptors and to other extracellular matrix proteins from both species, we conclude that these antigenic determinants may represent the actual sites for at least some of these interactions.