Lack of ß2 -adrenoceptors aggravates heart failure-induced skeletal muscle myopathy in mice.

Skeletal myopathy is a hallmark of heart failure (HF) and has been associated with a poor prognosis. HF and other chronic degenerative diseases share a common feature of a stressed system: sympathetic hyperactivity. Although beneficial acutely, chronic sympathetic hyperactivity is one of the main triggers of skeletal myopathy in HF. Considering that ß2 -adrenoceptors mediate the activity of sympathetic nervous system in skeletal muscle, we presently evaluated the contribution of ß2 -adrenoceptors for the morphofunctional alterations in skeletal muscle and also for exercise intolerance induced by HF. Male WT and ß2 -adrenoceptor knockout mice on a FVB genetic background (ß2 KO) were submitted to myocardial infarction (MI) or SHAM surgery. Ninety days after MI both WT and ß2 KO mice presented to cardiac dysfunction and remodelling accompanied by significantly increased norepinephrine and epinephrine plasma levels, exercise intolerance, changes towards more glycolytic fibres and vascular rarefaction in plantaris muscle. However, ß2 KO MI mice displayed more pronounced exercise intolerance and skeletal myopathy when compared to WT MI mice. Skeletal muscle atrophy of infarcted ß2 KO mice was paralleled by reduced levels of phosphorylated Akt at Ser 473 while increased levels of proteins related with the ubiquitin--proteasome system, and increased 26S proteasome activity. Taken together, our results suggest that lack of ß2 -adrenoceptors worsen and/or anticipate the skeletal myopathy observed in HF.

SJL dystrophic mice express a significant amount of human muscle proteins following systemic delivery of human adipose-derived stromal cells without immunosuppression.

Limb-girdle muscular dystrophies (LGMDs) are a heterogeneous group of disorders characterized by progressive degeneration of skeletal muscle caused by the absence of or defective muscular proteins. The murine model for limb-girdle muscular dystrophy 2B (LGMD2B), the SJL mice, carries a deletion in the dysferlin gene that causes a reduction in the protein levels to 15% of normal. The mice show muscle weakness that begins at 4-6 weeks and is nearly complete by 8 months of age. The possibility of restoring the defective muscle protein and improving muscular performance by cell therapy is a promising approach for the treatment of LGMDs or other forms of progressive muscular dystrophies. Here we have injected human adipose stromal cells (hASCs) into the SJL mice, without immunosuppression, aiming to assess their ability to engraft into recipient dystrophic muscle after systemic delivery; form chimeric human/mouse muscle fibers; express human muscle proteins in the dystrophic host and improve muscular performance. We show for the first time that hASCs are not rejected after systemic injection even without immunosuppression, are able to fuse with the host muscle, express a significant amount of human muscle proteins, and improve motor ability of injected animals. These results may have important applications for future therapy in patients with different forms of muscular dystrophies.

Sympathetic hyperactivity differentially affects skeletal muscle mass in developing heart failure: role of exercise training.

Sympathetic hyperactivity (SH) is a hallmark of heart failure (HF), and several lines of evidence suggest that SH contributes to HF-induced skeletal myopathy. However, little is known about the influence of SH on skeletal muscle morphology and metabolism in a setting of developing HF, taking into consideration muscles with different fiber compositions. The contribution of SH on exercise tolerance and skeletal muscle morphology and biochemistry was investigated in 3- and 7-mo-old mice lacking both alpha(2A)- and alpha(2C)-adrenergic receptor subtypes (alpha(2A)/alpha(2C)ARKO mice) that present SH with evidence of HF by 7 mo. To verify whether exercise training (ET) would prevent skeletal muscle myopathy in advanced-stage HF, alpha(2A)/alpha(2C)ARKO mice were exercised from 5 to 7 mo of age. At 3 mo, alpha(2A)/alpha(2C)ARKO mice showed no signs of HF and preserved exercise tolerance and muscular norepinephrine with no changes in soleus morphology. In contrast, plantaris muscle of alpha(2A)/alpha(2C)ARKO mice displayed hypertrophy and fiber type shift (IIA --> IIX) paralleled by capillary rarefaction, increased hexokinase activity, and oxidative stress. At 7 mo, alpha(2A)/alpha(2C)ARKO mice displayed exercise intolerance and increased muscular norepinephrine, muscular atrophy, capillary rarefaction, and increased oxidative stress. ET reestablished alpha(2A)/alpha(2C)ARKO mouse exercise tolerance to 7-mo-old wild-type levels and prevented muscular atrophy and capillary rarefaction associated with reduced oxidative stress. Collectively, these data provide direct evidence that SH is a major factor contributing to skeletal muscle morphological changes in a setting of developing HF. ET prevented skeletal muscle myopathy in alpha(2A)/alpha(2C)ARKO mice, which highlights its importance as a therapeutic tool for HF.

Evaluation of ions and metals in the blood of GRMD dogs submitted to hASCs therapy by NAA and XRF techniques.

The elements Br, Ca, Cl, Cr, Fe, K, Mg, Na, P, Rb, S, and Zn were investigated in the whole blood samples of Golden Retriever dogs submitted to cell therapy (hASCs). These analyses were performed over 2 years using Neutron Activation Analysis and X-Ray Fluorescence techniques. The results were compared with control and untreated dog's. A significant increase was observed in K blood levels. There was also variation in blood levels of Br, Cr, Fe, Rb, S, and Zn.

Impact of long-term high-intensity interval and moderate-intensity continuous training on subclinical inflammation in overweight/obese adults.

Obesity is a risk factor able to trigger several inflammatory alterations and the imbalance between pro- and anti-inflammatory cytokine productions. Physical exercise is an important strategy for reduction of inflammatory established process. The aim of this study was to evaluate the effect of 16 weeks of three exercise training programs in the inflammatory profile and insulin resistance in overweight/obesity. Thirty two men and women (46.4±10.1 years; 162.0±9.1 cm; 82.0±13.6 kg) were divided into three groups for training on a treadmill: continuous at 70% maximum heart rate (HRmax) 5 times a week (CONT); 1×4 min (1-bout) and 4×4 min (high intensity interval training, HIIT) at 90% HRmax 3 times a week. Interleukin (IL) 6 and IL-10, tumor necrosis factor-alpha (TNF-α), insulin and adiponectin levels were analyzed by enzyme-linked immunosorbent assay, and homeostasis model assessment insulin resistance was calculated. After 16 weeks of training blood concentrations of IL-6 decreased in the HIIT group (P=0.035), TNF-α decreased in the CONT (P=0.037) and increased in HIIT (P=0.001) and adiponectin decreased in the three training models. There was a trend towards decreased body weight and body mass index (BMI) after HIIT only (P=0.059 and P=0.060, respectively). Despite the decrease of adiponectin and the increase of TNF-α in HIIT group, insulin sensitivity showed a trend for improvement (P=0.08). HIIT program decreased IL-6 at rest and although not significant was the only who tended to decrease total body weight and BMI. Taken together, our data suggest that both HIIT as well as CONT exercises training program promotes changes in inflammatory profile in overweight/obesity, but dissimilar response is seen in TNF-α levels.

Maternal postnatal high-fat diet, rather than gestational diet, affects morphology and mTOR pathway in skeletal muscle of weaning rat.

The positive regulation of insulin pathway in skeletal muscle results in increased activity of the mammalian target of rapamycin (mTOR), a positive effector of mRNA translation rate and protein synthesis. Studies that assess the activity of this protein in response to chronic high-fat diet (HFD) are scarce and controversial, and to date, there are no studies evaluating the mTOR pathway in infants exposed to gestational and postgestational HFD. This study investigated the effect of maternal HFD on skeletal muscle morphology and on phosphorylation of proteins that comprise the intracellular mTOR signaling pathway in soleus muscle of offspring at weaning. For this purpose, 10 days prior to conception, 39 female Wistar rats were randomly assigned to either control diet (CTL) or HFD. Later, rats were distributed into four groups according to gestational and postpregnancy diet: CTL/CTL (n=10), CTL/HF (n=11), HF/HF (n=10) and HF/CTL (n=8). After 21 days of lactation, pups were killed, and blood samples and soleus and gastrocnemius skeletal muscle were collected for analysis. We observed an influence of maternal postgestational diet, rather than gestational diet, in promoting an obese phenotype, characterized by body fat accumulation, insulin resistance and high serum leptin, glucose, triglycerides and cholesterol levels (P<.05). We have also detected alterations on skeletal muscle morphology--with reduced myofiber density--and impairment on S6 kinase 1 and 4E binding protein-1 phosphorylation (P<.05). These results emphasize the importance of maternal diet during lactation on muscle morphology and on physiological adaptations of infant rats.

Aerobic exercise training upregulates skeletal muscle calpain and ubiquitin-proteasome systems in healthy mice.

Aerobic exercise training (AET) is an important mechanical stimulus that modulates skeletal muscle protein turnover, leading to structural rearrangement. Since the ubiquitin-proteasome system (UPS) and calpain system are major proteolytic pathways involved in protein turnover, we aimed to investigate the effects of intensity-controlled AET on the skeletal muscle UPS and calpain system and their association to training-induced structural adaptations. Long-lasting effects of AET were studied in C57BL/6J mice after 2 or 8 wk of AET. Plantaris cross-sectional area (CSA) and capillarization were assessed by myosin ATPase staining. mRNA and protein expression levels of main components of the UPS and calpain system were evaluated in plantaris by real-time PCR and Western immunoblotting, respectively. No proteolytic system activation was observed after 2 wk of AET. Eight weeks of AET resulted in improved running capacity, plantaris capillarization, and CSA. Muscle RING finger-1 mRNA expression was increased in 8-wk-trained mice. Accordingly, elevated 26S proteasome activity was observed in the 8-wk-trained group, without accumulation of ubiquitinated or carbonylated proteins. In addition, calpain abundance was increased by 8 wk of AET, whereas no difference was observed in its endogenous inhibitor calpastatin. Taken together, our findings indicate that skeletal muscle enhancements, as evidenced by increased running capacity, plantaris capillarization, and CSA, occurred in spite of the upregulated UPS and calpain system, suggesting that overactivation of skeletal muscle proteolytic systems is not restricted to atrophying states. Our data provide evidence for the contribution of the UPS and calpain system to metabolic turnover of myofibrillar proteins and skeletal muscle adaptations to AET.

Ringo: discordance between the molecular and clinical manifestation in a golden retriever muscular dystrophy dog.

Of the various genetic homologues to Duchenne Muscular Dystrophy (DMD), the Golden Retriever Muscular Dystrophy (GRMD) dog, which presents a variable but usually severe and progressive muscle weakness, has the closest relevance to DMD in both clinical severity and histopathological change. Among 77 GRMD dogs born in our colony in Brazil, we have identified a very mildly affected dog, Ringo, born July 2003. Among his descendants, at least one male, Suflair, is also showing a mild course. In an attempt to better characterize these two dogs, we studied the pattern of muscle proteins expression in Ringo and Suflair, as compared to severely affected and normal control dogs. Dystrophin was absent in both and utrophin was overexpressed in a pattern similar to the observed in severely affected dogs. Understanding the mechanism that is protecting Ringo and Suflair from the deleterious effect of the dystrophin gene mutation is of utmost interest. In addition it points out that the clinical impact of therapeutic trials should be interpreted with caution.

Aerobic exercise training improves Ca2+ handling and redox status of skeletal muscle in mice.

Exercise training is known to promote relevant changes in the properties of skeletal muscle contractility toward powerful fibers. However, there are few studies showing the effect of a well-established exercise training protocol on Ca(2+) handling and redox status in skeletal muscles with different fiber-type compositions. We have previously standardized a valid and reliable protocol to improve endurance exercise capacity in mice based on maximal lactate steady-state workload (MLSSw). The aim of this study was to investigate the effect of exercise training, performed at MLSSw, on the skeletal muscle Ca(2+) handling-related protein levels and cellular redox status in soleus and plantaris. Male C57BL/6J mice performed treadmill training at MLSSw over a period of eight weeks. Muscle fiber-typing was determined by myosin ATPase histochemistry, citrate synthase activity by spectrophotometric assay, Ca(2+) handling-related protein levels by Western blot and reduced to oxidized glutathione ratio (GSH:GSSG) by high-performance liquid chromatography. Trained mice displayed higher running performance and citrate synthase activity compared with untrained mice. Improved running performance in trained mice was paralleled by fast-to-slow fiber-type shift and increased capillary density in both plantaris and soleus. Exercise training increased dihydropyridine receptor (DHPR) alpha2 subunit, ryanodine receptor and Na(+)/Ca(2+) exchanger levels in plantaris and soleus. Moreover, exercise training elevated DHPR beta1 subunit and sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) 1 levels in plantaris and SERCA2 levels in soleus of trained mice. Skeletal muscle GSH content and GSH:GSSG ratio was increased in plantaris and soleus of trained mice. Taken together, our findings indicate that MLSSw exercise-induced better running performance is, in part, due to increased levels of proteins involved in skeletal muscle Ca(2+) handling, whereas this response is partially dependent on specificity of skeletal muscle fiber-type composition. Finally, we demonstrated an augmented cellular redox status and GSH antioxidant capacity in trained mice.

RECIPROC: comparativo entre a cinemática reciprocante e rotatória em canais curvos / RECIPROC: a comparison between reciprocating and rotational kinematics in curved canals

Objetivo: Comparou o tempo de preparo, ocorrência de fratura e manutenção do trajeto do canal em canais artificiais do instrumento Reciproc R25 em movimento reciprocante e rotação contínua anti-horária. Material e Métodos: Foram utilizados dois grupos contendo 10 canais artificiais em blocos de acrílico cada, sendo um o grupo controle, instrumentado com movimento reciprocante, e o grupo teste utilizando rotação contínua anti-horária a 300rpm para a instrumentação. Resultados: os resultados mostraram que houve diferença estatística significante em relação ao tempo de preparo entre os grupos, uma vez que a rotação contínua anti-horária proporcionou um menor tempo de preparo; ambos mantiveram o trajeto original do canal sem qualquer desvios no terço apical e ocorreu uma fratura no grupo da rotação contínua. Conclusão: o sistema Reciproc manteve a trajetória original do canal, não influenciou na incidência de fratura dos instrumentos e demandou menor tempo de preparo utilizando rotação contínua. Portanto, o sistema Reciproc pode ser utilizado com rotação contínua anti-horária desde que velocidade, torque e pressão apical sejam respeitados e se empregue os instrumento uma única vez.

Objective: This study aimed to compare the preparation time, occurrence of fracture and maintenance of the canal path in artificial canals using Reciproc R25 instrument moving reciprocating and continuous counterclockwise rotation. Methods: Two groups of 10 Simulated rootcanals, each one in an artificial acrylic block, was instrumented with reciprocating motion (control group) and using counterclockwise continuous rotation to 300rpm (test group). Results: The results showed statistically significant difference in relation to the preparation time between the groups, since the counterclockwise continuous rotation allowed shorter preparation time, both kinematics kept the original route of the canal without any deviations in the apical third. A fracture occurred in the group of continuous rotation. Conclusion: The Reciproc system kept the original trajectory of the canals and did not influence the incidence of instruments fracture. A less preparation time was required when the continuous rotation was used. Therefore, the Reciproc system can be used with counterclockwise continuous rotation since that speed, torque and apical pressure are respected. The instrument also should be employed just one time.