Electrical activity of the orbicularis muscles before and after installation of ocular prostheses

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Histochemistry profile of the biceps brachii muscle fibres of capuchin monkeys (Cebus apella, Linnaeus, 1758)

A general analysis of the behaviour of "Cebus" shows that when this primate moves position to feed or perform another activity, it presents different ways of locomotion. This information shows that the brachial biceps muscle of this animal is frequently used in their locomotion activities, but it should also be remembered that this muscle is also used for other development activities like hiding, searching for objects, searching out in the woods, and digging in the soil. Considering the above, it was decided to research the histoenzimologic characteristics of the brachial biceps muscle to observe whether it is better adpted to postural or phasic function. To that end, samples were taken from the superficial and deep regions, the inserts proximal (medial and lateral) and distal brachial biceps six capuchin monkeys male and adult, which were subjected to the reactions of m-ATPase, NADH-Tr. Based on the results of these reactions fibres were classified as in Fast Twitch Glycolitic (FG), Fast Twitch Oxidative Glycolitic (FOG) and Slow Twitc (SO). In general, the results, considering the muscle as a whole, show a trend of frequency FOG>FG>SO. The data on the frequency were studied on three superficial regions FOG=FG>SO; the deep regions of the inserts proximal FOG=FG=SO and inserting the distal FOG>FG=SO. In conclusion, the biceps brachii of the capuchin monkey is well adapted for both postural and phasic activities.

Electromyographic study of the trapezius muscle in free movements of the arm

The trapezius muscle (superior, middle and inferior portions) was analyzed in 20 volunteers. The electromyographic tests were carried out using a four-channel TECA TE 2-7 electromyograph with surface- and single coaxial needle electrodes. In abduction, adduction and flexion-extension, the 3 portions show increasing and decreasing activity, respectively, from the beginning until the end of these movements. In hyperextension, the 3 portions show increasing activity from the beginning until the end of the movement, with greater participation of the middle portion. Significant differences were not observed in the electromyographic profile of the trapezius, using surface and needle electrodes.

Electromyographic study of the trapezius muscle in free movements of the shoulder

The objective of this study is to analyze the simultaneity of the actions of the three portions of the trapezius (superior portion = TS; middle portion = TM and inferior portion = TI) in elevation, lowering, retraction and protraction of the shoulders. The electromyographic tests were carried out in 20 volunteers using a 4-channel TECA TE 2-7 electromyograph and surface and single coaxial needle electrodes. The electromyographs, obtained with the two types of electrodes, show that in elevation and lowering of the shoulders, TS and TM present increasing and decreasing activity, respectively, from the beginning until the end of these movements. In retraction of the shoulders, TM and TI present increasing activity from the beginning to the end of the movement. In protraction, TS, TM and TI do not show any activity.

PREPARATORY EMG ACTIVITY REVEALS A RAPID ADAPTATION PATTERN IN HUMANS PERFORMING LANDING MOVEMENTS IN BLINDFOLDED CONDITION

The main questions addressed in this work were whether and how adaptation to suppression of visual information occurs in a free-fall paradigm, and the extent to which vision availability influences the control of landing movements. The prelanding modulation of EMG timing and amplitude of four lower-limb muscles was investigated. Participants performed six consecutive drop-landings from four different heights in two experimental conditions: with and without vision. Experimental design precluded participants from estimating the height of the drop. Since cues provided by proprioceptive and vestibular information acquired during the first trials were processed, the nervous system rapidly adapted to the lack of visual information, and hence produced a motor output (i.e., prelanding EMG modulation) similar to that observed when performing the activity with vision available.

Effect of simvastatin on passive strain-induced skeletal muscle injury in rats

Introduction: HMG-CoA reductase inhibitors are the most frequently prescribed drugs for treatment of lipid imbalance, but they have side effects, such as myopathy. Our aim was to assess the effect of simvastatin on the inflammatory process induced by skeletal muscle injury. Methods: Rats were divided into experimental groups [control group, simvastatin (20 mg/kg) group, group treated with simvastatin (20 mg/kg) and subjected to injury, and group subjected to injury only]. Histological analysis and analyses of creatine kinase activity and C-reactive protein were performed. Results: Animals treated with simvastatin exhibited significantly greater morphological and structural skeletal muscle damage in comparison to the control group and injured animals without treatment. Conclusions: Although simvastatin has a small anti-inflammatory effect in the early stage after a muscle strain injury, the overall picture is negative, as simvastatin increases the extent of damage to muscle morphology. Further studies are needed. Muscle Nerve 46: 908-913, 2012

Ultrastructural features of the myotendinous junction of the sternomastoid muscle in Wistar rats: from newborn to aging

The myotendinous junction (MTJ) is a major area for transmitting force from the skeletal muscle system and acts in joint position and stabilization. This study aimed to use transmission electron microscopy to describe the ultrastructural features of the MTJ of the sternomastoid muscle in Wistar rats from newborn to formation during adulthood and possible changes with aging. Ultrastructural features of the MTJ from the newborn group revealed pattern during development with interactions between muscle cells and extracellular matrix elements with thin folds in the sarcolemma and high cellular activity evidenced through numerous oval mitochondria groupings. The adult group had classical morphological features of the MTJ, with folds in the sarcolemma forming long projections called finger-like processes and sarcoplasmic invaginations. Sarcomeres were aligned in series, showing mitochondria near the Z line in groupings between collagen fiber bundles. The old group had altered finger-like processes, thickened in both levels of sarcoplasmic invaginations and in central connections with the lateral junctions. We conclude that the MTJ undergoes intense activity from newborn to its formation during adulthood. With increasing age, changes to the MTJ were observed in the shapes of the invaginations and finger-like processes due to hypoactivity, potentially compromising force transmission and joint stability. Microsc. Res. Tech. 75:12921296, 2012. (C) 2012 Wiley Periodicals, Inc.

Lack of beta(2)-AR improves exercise capacity and skeletal muscle oxidative phenotype in mice

beta(2)-adrenergic receptor (beta(2)-AR) agonists have been used as ergogenics by athletes involved in training for strength and power in order to increase the muscle mass. Even though anabolic effects of beta(2)-AR activation are highly recognized, less is known about the impact of beta(2)-AR in endurance capacity. We presently used mice lacking beta(2)-AR [beta(2)-knockout (beta(2) KO)] to investigate the role of beta(2)-AR on exercise capacity and skeletal muscle metabolism and phenotype. beta(2) KO mice and their wild-type controls (WT) were studied. Exercise tolerance, skeletal muscle fiber typing, capillary-to-fiber ratio, citrate synthase activity and glycogen content were evaluated. When compared with WT, beta 2KO mice displayed increased exercise capacity (61%) associated with higher percentage of oxidative fibers (21% and 129% of increase in soleus and plantaris muscles, respectively) and capillarity (31% and 20% of increase in soleus and plantaris muscles, respectively). In addition, beta 2KO mice presented increased skeletal muscle citrate synthase activity (10%) and succinate dehydrogenase staining. Likewise, glycogen content (53%) and periodic acid-Schiff staining (glycogen staining) were also increased in beta 2KO skeletal muscle. Altogether, these data provide evidence that disruption of beta(2)AR improves oxidative metabolism in skeletal muscle of beta 2KO mice and this is associated with increased exercise capacity.

Immunological parameters in elderly women: Correlations with aerobic power, muscle strength and mood state

Purpose: Our objective was to relate immunological data for healthy but sedentary elderly women to aerobic power, strength, and mood state. Methods: We measured peak aerobic power and one-repetition maximum strength along with mood (depression and fatigue), quality of life and carbohydrate intake on 42 women aged 60-77 years. Standard immunological techniques determined natural killer cell count and cytotoxic activity (NKCA), proliferative responses to phytohemaglutinin and OKT3, various lymphocyte subpopulations (CD3(+), CD3(-)CD19(+), CD56(+), CD4(+), CD8(+), CD56(dim) and CD56(bright)), and markers of activation, maturation, down-regulation and susceptibility to apoptosis (CD25(+), CD28(+), CD45RA(+), CD45RO(+), CD69(+), CD95(+), HLA-DR+). Results: Correlations of immune parameters with aerobic power and strength were very similar for absolute and relative immunological data. In the group as a whole, the only correlation with aerobic power was -0.35 (relative CD4(+)CD69(+) count), but in subjects with values <22.6 mL kg(-1) min(-1) correlations ranged from -0.57 (relative CD4(+)CD45RO(+)) to 0.92 (absolute CD56(dim)HLA-DR+). In terms of muscle strength, univariate correlation coefficients ranged from -0.34 (relative and absolute CD3(+)CD4(+)CD8(+)) to +0.48 (absolute CD3(+)HLA-DR+.) and +0.50 (absolute CD8(+)CD45RA(+)CD45RO(+)). Neither NKCA nor lymphocyte proliferation were correlated with aerobic power or muscle strength. Although mood state and quality of life can sometimes be influenced by an individual's fitness level, our multivariate analyses suggested that depression, fatigue and quality of life were more important determinants of immune profile than our fitness measures. Conclusions: Psychological changes associated with aging may have a substantial adverse effect upon the immune system, and immunological function may be enhanced more by addressing these issues than by focusing upon aerobic or resistance training. (C) 2012 Elsevier Inc. All rights reserved.

Metabolic and functional effects of beta-hydroxy-beta-methylbutyrate (HMB) supplementation in skeletal muscle

Beta-hydroxy-beta-methylbutyrate (HMB) is a metabolite derived from leucine. The anti-catabolic effect of HMB is well documented but its effect upon skeletal muscle strength and fatigue is still uncertain. In the present study, male Wistar rats were supplemented with HMB (320 mg/kg per day) for 4 weeks. Placebo group received saline solution only. Muscle strength (twitch and tetanic force) and resistance to acute muscle fatigue of the gastrocnemius muscle were evaluated by direct electrical stimulation of the sciatic nerve. The content of ATP and glycogen in red and white portions of gastrocnemius muscle were also evaluated. The effect of HMB on citrate synthase (CS) activity was also investigated. Muscle tetanic force was increased by HMB supplementation. No change was observed in time to peak of contraction and relaxation time. Resistance to acute muscle fatigue during intense contractile activity was also improved after HMB supplementation. Glycogen content was increased in both white (by fivefold) and red (by fourfold) portions of gastrocnemius muscle. HMB supplementation also increased the ATP content in red (by twofold) and white (1.2-fold) portions of gastrocnemius muscle. CS activity was increased by twofold in red portion of gastrocnemius muscle. These results support the proposition that HMB supplementation have marked change in oxidative metabolism improving muscle strength generation and performance during intense contractions.

Reduced muscle carnosine content in type 2, but not in type 1 diabetic patients

Carnosine is present in high concentrations in skeletal muscle where it contributes to acid buffering and functions also as a natural protector against oxidative and carbonyl stress. Animal studies have shown an anti-diabetic effect of carnosine supplementation. High carnosinase activity, the carnosine degrading enzyme in serum, is a risk factor for diabetic complications in humans. The aim of the present study was to compare the muscle carnosine concentration in diabetic subjects to the level in non-diabetics. Type 1 and 2 diabetic patients and matched healthy controls (total n = 58) were included in the study. Muscle carnosine content was evaluated by proton magnetic resonance spectroscopy (3 Tesla) in soleus and gastrocnemius. Significantly lower carnosine content (-45%) in gastrocnemius muscle, but not in soleus, was shown in type 2 diabetic patients compared with controls. No differences were observed in type 1 diabetic patients. Type II diabetic patients display a reduced muscular carnosine content. A reduction in muscle carnosine concentration may be partially associated with defective mechanisms against oxidative, glycative and carbonyl stress in muscle.

Exercise training prevents oxidative stress and ubiquitin-proteasome system overactivity and reverse skeletal muscle atrophy in heart failure

Background: Heart failure (HF) is known to lead to skeletal muscle atrophy and dysfunction. However, intracellular mechanisms underlying HF-induced myopathy are not fully understood. We hypothesized that HF would increase oxidative stress and ubiquitin-proteasome system (UPS) activation in skeletal muscle of sympathetic hyperactivity mouse model. We also tested the hypothesis that aerobic exercise training (AET) would reestablish UPS activation in mice and human HF. Methods/Principal Findings: Time-course evaluation of plantaris muscle cross-sectional area, lipid hydroperoxidation, protein carbonylation and chymotrypsin-like proteasome activity was performed in a mouse model of sympathetic hyperactivity-induced HF. At the 7th month of age, HF mice displayed skeletal muscle atrophy, increased oxidative stress and UPS overactivation. Moderate-intensity AET restored lipid hydroperoxides and carbonylated protein levels paralleled by reduced E3 ligases mRNA levels, and reestablished chymotrypsin-like proteasome activity and plantaris trophicity. In human HF (patients randomized to sedentary or moderate-intensity AET protocol), skeletal muscle chymotrypsin-like proteasome activity was also increased and AET restored it to healthy control subjects' levels. Conclusions: Collectively, our data provide evidence that AET effectively counteracts redox imbalance and UPS overactivation, preventing skeletal myopathy and exercise intolerance in sympathetic hyperactivity-induced HF in mice. Of particular interest, AET attenuates skeletal muscle proteasome activity paralleled by improved aerobic capacity in HF patients, which is not achieved by drug treatment itself. Altogether these findings strengthen the clinical relevance of AET in the treatment of HF.

Beta-alanine (Carnosyn (TM)) supplementation in elderly subjects (60-80 years): effects on muscle carnosine content and physical capacity

The aim of this study was to investigate the effects of beta-alanine supplementation on exercise capacity and the muscle carnosine content in elderly subjects. Eighteen healthy elderly subjects (60-80 years, 10 female and 4 male) were randomly assigned to receive either beta-alanine (BA, n = 12) or placebo (PL, n = 6) for 12 weeks. The BA group received 3.2 g of beta-alanine per day (2 x 800 mg sustained-release Carnosyn (TM) tablets, given 2 times per day). The PL group received 2 x (2 x 800 mg) of a matched placebo. At baseline (PRE) and after 12 weeks (POST-12) of supplementation, assessments were made of the muscle carnosine content, anaerobic exercise capacity, muscle function, quality of life, physical activity and food intake. A significant increase in the muscle carnosine content of the gastrocnemius muscle was shown in the BA group (+85.4%) when compared with the PL group (+7.2%) (p = 0.004; ES: 1.21). The time-to-exhaustion in the constant-load submaximal test (i.e., TLIM) was significantly improved (p = 0.05; ES: 1.71) in the BA group (+36.5%) versus the PL group (+8.6%). Similarly, time-to-exhaustion in the incremental test was also significantly increased (p = 0.04; ES 1.03) following beta-alanine supplementation (+12.2%) when compared with placebo (+0.1%). Significant positive correlations were also shown between the relative change in the muscle carnosine content and the relative change in the time-to-exhaustion in the TLIM test (r = 0.62; p = 0.01) and in the incremental test (r = 0.48; p = 0.02). In summary, the current data indicate for the first time, that beta-alanine supplementation is effective in increasing the muscle carnosine content in healthy elderly subjects, with subsequent improvement in their exercise capacity.

Comparison between multiple sets and half-pyramid resistance exercise bouts for muscle damage profile

The present study compared the changes in markers of muscle damage after bouts of resistance exercise employing the Multiple-sets (MS) and Half-pyramid (HP) training systems. Ten healthy men (26.1 +/- 6.3 years), who had been involved in regular resistance training, performed MS and HP bouts, 14 days apart, in a randomised, counter-balanced manner. For the MS bout, participants performed three sets of maximum repetitions at 75%-1RM (i.e. 75% of a One Repetition Maximum) for the three exercises, starting with the bench press, followed by pec deck and decline bench press. For the HP bout, the participants performed three sets of maximum repetitions with 67%-1RM, 74%-1RM and 80%-1RM for the first, second and third sets, respectively, for the same three exercise sequences as the MS bout. The total volume of load lifted was equated between both bouts. Muscle soreness, plasma creatine kinase (CK) activity, myoglobin (Mb) and C-reactive protein (CRP) concentrations were assessed before and for three days after each exercise bout, and the changes over time were compared between MS and HP using two-way repeated measures ANOVA. Muscle soreness developed significantly (P<0.01) after both bouts, but no significant difference was observed between MS and HP. Plasma CK activity and Mb concentration increased significantly (P<0.01) without significant differences between bouts, and CRP concentration did not change significantly after either bout. These results suggest that the muscle damage profile is similar for MS and HP, probably due to the similar total volume of load lifted.

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

Cunha TF, Moreira JB, Paixao NA, Campos JC, Monteiro AW, Bacurau AV, Bueno CR Jr., Ferreira JC, Brum PC. Aerobic exercise training upregulates skeletal muscle calpain and ubiquitin-proteasome systems in healthy mice. J Appl Physiol 112: 1839-1846, 2012. First published March 29, 2012; doi:10.1152/japplphysiol.00346.2011.-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.