Conformational stability of peanut agglutinin using small angle X-ray scattering

In this work, quaternary conformational studies of peanut agglutinin (PNA) have been carried out using small-angle X-ray scattering (SAXS). PNA was submitted to three different conditions: pH variation (2.5, 4.0, 7.4 and 9.0), guanidine hydrochloride presence (0.5-2 M) at each pH value, and temperature ranging from 25 to 60 degrees C. All experiments were performed in the absence and presence of T-antigen to evaluate its influence on the lectin stability. At room temperature and pH 4.0,7.4 and 9.0, the SAXS curves are consistent with the PNA scattering in its crystallographic native homotetrameric structure, with monomers in a jelly roll fold, associated by non-covalent bonds resulting in an open structure. At pH 2.5, the results indicate that PNA tends to dissociate into smaller sub-units, as dimers and monomers, followed by a self-assembling into larger aggregates. Furthermore, the conformational stability under thermal denaturation follows the pH sequence 7.4 > 9.0 > 4.0 > 2.5. Such results are consistent with the conformational behavior found upon GndHCl influence. The presence of T-antigen does not affect the protein quaternary structure in all studied systems within the SAXS resolution. (C) 2010 Elsevier B.V. All rights reserved.

Leg preference and interlateral asymmetry of balance stability in soccer players

To examine the effect of long lasting practice on pedal behavior in sport, we compared experienced adult soccer players and nonsoccer players on leg preference in motor tasks requiring general mobilization, soccer related mobilization, and body balance stabilization. We also evaluated performance asymmetry between the right and left legs in static and dynamic unipedal body balance based on center of pressure displacement, and correlated that with kg preference in balance stabilization tasks. Results revealed (a) a distinct leg preference between mobilization and stabilization tasks, which were significantly different between Mayers and nonplayers, (b) similar balance stability between the right and left legs, (c) greater stability of experienced players compared with nonplayers in static and dynamic balance, and (d) absence of a significant kg preference correlation with interlateral balance asymmetry. These results suggest an effect of extensive soccer skill practice on establishing leg preference for specific mobilization tasks and overall balance control.

Aerobic exercise training improves skeletal muscle function and Ca(2+) handling-related protein expression in sympathetic hyperactivity-induced heart failure

Bueno CR Jr, Ferreira JC, Pereira MG, Bacurau AV, Brum PC. Aerobic exercise training improves skeletal muscle function and Ca(2+) handling-related protein expression in sympathetic hyperactivity-induced heart failure. J Appl Physiol 109: 702-709, 2010. First published July 1, 2010; doi: 10.1152/japplphysiol.00281.2010.-The cellular mechanisms of positive effects associated with aerobic exercise training on overall intrinsic skeletal muscle changes in heart failure (HF) remain unclear. We investigated potential Ca(2+) abnormalities in skeletal muscles comprising different fiber compositions and investigated whether aerobic exercise training would improve muscle function in a genetic model of sympathetic hyperactivity-induced HF. A cohort of male 5-mo-old wild-type (WT) and congenic alpha(2A)/alpha(2C) adrenoceptor knockout (ARKO) mice in a C57BL/6J genetic background were randomly assigned into untrained and trained groups. Exercise training consisted of a 8-wk running session of 60 min, 5 days/wk (from 5 to 7 mo of age). After completion of the exercise training protocol, exercise tolerance was determined by graded treadmill exercise test, muscle function test by Rotarod, ambulation and resistance to inclination tests, cardiac function by echocardiography, and Ca(2+) handling-related protein expression by Western blot. alpha(2A)/alpha(2C)ARKO mice displayed decreased ventricular function, exercise intolerance, and muscle weakness paralleled by decreased expression of sarcoplasmic Ca(2+) release-related proteins [alpha(1)-, alpha(2)-, and beta(1)-subunits of dihydropyridine receptor (DHPR) and ryanodine receptor (RyR)] and Ca(2+) reuptake-related proteins [sarco(endo) plasmic reticulum Ca(2+)-ATPase (SERCA) 1/2 and Na(+)/Ca(2+) exchanger (NCX)] in soleus and plantaris. Aerobic exercise training significantly improved exercise tolerance and muscle function and reestablished the expression of proteins involved in sarcoplasmic Ca(2+) handling toward WT levels. We provide evidence that Ca(2+) handling-related protein expression is decreased in this HF model and that exercise training improves skeletal muscle function associated with changes in the net balance of skeletal muscle Ca(2+) handling proteins.

Aerobic exercise training improves Ca(2+) 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) alpha 2 subunit, ryanodine receptor and Na(+)/Ca(2+) exchanger levels in plantaris and soleus. Moreover, exercise training elevated DHPR beta 1 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.

Cardiac anti-remodelling effect of aerobic training is associated with a reduction in the calcineurin/NFAT signalling pathway in heart failure mice

Cardiomyocyte hypertrophy occurs in response to a variety of physiological and pathological stimuli. While pathological hypertrophy in heart failure is usually coupled with depressed contractile function, physiological hypertrophy associates with increased contractility. In the present study, we explored whether 8 weeks of moderate intensity exercise training would lead to a cardiac anti-remodelling effect in an experimental model of heart failure associated with a deactivation of a pathological (calcineurin/NFAT, CaMKII/HDAC) or activation of a physiological (Akt-mTOR) hypertrophy signalling pathway. The cardiac dysfunction, exercise intolerance, left ventricle dilatation, increased heart weight and cardiomyocyte hypertrophy from mice lacking alpha(2A) and alpha(2C) adrenoceptors (alpha(2A)/alpha(2C)ARKO mice) were associated with sympathetic hyperactivity induced heart failure. The relative contribution of Ca(2+)-calmodulin high-affinity (calcineurin/NFAT) and low-affinity (CaMKII/HDAC) targets to pathological hypertrophy of alpha(2A)/alpha(2C)ARKO mice was verified. While nuclear calcineurin B, NFATc3 and GATA-4 translocation were significantly increased in alpha(2A)/alpha(2C)ARKO mice, no changes were observed in CaMKII/HDAC activation. As expected, cyclosporine treatment decreased nuclear translocation of calcineurin/NFAT in alpha(2A)/alpha(2C)ARKO mice, which was associated with improved ventricular function and a pronounced anti-remodelling effect. The Akt/mTOR signalling pathway was not activated in alpha(2A)/alpha(2C)ARKO mice. Exercise training improved cardiac function and exercise capacity in alpha(2A)/alpha(2C)ARKO mice and decreased heart weight and cardiomyocyte width paralleled by diminished nuclear NFATc3 and GATA-4 translocation as well as GATA-4 expression levels. When combined, these findings support the notion that deactivation of calcineurin/NFAT pathway-induced pathological hypertrophy is a preferential mechanism by which exercise training leads to the cardiac anti-remodelling effect in heart failure.

Aerobic profile of climbers during maximal arm test

This study compared measurements of upper body aerobic fitness in elite (EC; n = 7) and intermediate rock climbers (IC; n = 7), and a control group (C; n = 7). Subjects underwent an upper limb incremental test on hand cycle ergometer, with increments of 23 W.min(-1), until exhaustion. Ventilation (VE) data were smoothed to 10 s averages and plotted against time for the visual determination of the first (VT1) and second (VT2) ventilatory thresholds. Peak power output was not different among groups [EC = 130.9 (+/- 11.8) W; IC = 122.1 (+/- 28.4) W; C = 115.4 (+/- 15.1) W], but time to exhaustion was significantly higher in EC than IC and C. VO(2PEAK) was significantly higher in EC [36.8 (+/- 5.7) mL.kg(-1).min(-1)] and IC [35.5 (+/- 5.2) mL.kg(-1).min(-1)] than C [28.8 (+/- 5.0) mL.kg(-1).min(-1)], but there was no difference between EC and IC. VT1 was significantly higher in EC than C [EC = 69.0 (+/- 9.4) W; IC = 62.4 (+/- 13.0) W; C = 52.1 (+/- 11.8) W], but no significant difference was observed in VT2 [EC = 103.5 (+/- 18.8) W; IC = 92.0 (+/- 22.0) W; C = 85.6 (+/- 19.7) W]. These results show that elite indoor rock climbers elicit higher aerobic fitness profile than control subjects when measured with an upper body test.

Aerobic exercise is safe and effective in systemic sclerosis

Several studies have established that systemic sclerosis patients have a reduced exercise capacity when compared to healthy individuals. It is relevant to evaluate whether aerobic exercise in systemic sclerosis patients is a safe and effective intervention to improve aerobic capacity. Seven patients without pulmonary impairment and seven healthy controls were enrolled in an 8-week program consisting of moderate intensity aerobic exercise. Patients and controls had a significant improvement in peak oxygen consumption (19.72 +/- 3.51 vs. 22.27 +/- 2.53 and 22.94 +/- 4.70 vs. 24.55 +/- 3.00, respectively, p = 0.006), but difference between groups was not statistically significant (p = 0.149). This finding was reinforced by the fact that at the end of the study both groups were able to perform a significantly higher exercise intensity when compared to baseline, as measured by peak blood lactate (1.43 +/- 0.51 vs. 1.84 +/- 0.33 and 1.11 +/- 0.45 vs. 1.59 +/- 0.25, respectively, p = 0.01). Patients improved the peak exercise oxygen saturation comparing to the baseline (84.14 +/- 9.86 vs. 90.29 +/- 5.09, p = 0.048). Rodnan score was similar before and after the intervention(15.84 +/- 7.84 vs. 12.71 +/- 4.31, p = 0.0855). Digital ulcers and Raynaud`s phenomenon remained stable. Our data support the notion that improving aerobic capacity is a feasible goal in systemic sclerosis management. The long term benefit of this intervention needs to be determined in large prospective studies.

Influence of angiotensinogen and angiotensin-converting enzyme polymorphisms on cardiac hypertrophy and improvement on maximal aerobic capacity caused by exercise training

Background The allele threonine (T) of the angiotensinogen has been associated with ventricular hypertrophy in hypertensive patients and soccer players. However, the long-term effect of physical exercise in healthy athletes carrying the T allele remains unknown. We investigated the influence of methionine M or T allele of the angiotensinogen and D or I allele of the angiotensin-converting enzyme on left-ventricular mass index (LVMI) and maximal aerobic capacity in young healthy individuals after long-term physical exercise training. Design Prospective clinical trial. Methods Eighty-three policemen aged between 20 and 35 years (mean +/- SD 26 +/- 4.5 years) were genotyped for the M235T gene angiotensinogen polymorphism (TT, n=25; MM/MT, n=58) and angiotensin-converting enzyme gene insertion/deletion (I/D) polymorphism (11, n=18; DD/DI, n=65). Left-ventricular morphology was evaluated by echocardiography and maximal aerobic capacity (VO(2peak)) by cardiopulmonary exercise test before and after 17 weeks of exercise training (50-80% VO(2peak)). Results Baseline VO(2peak) and LVMI were similar between TT and MM/MT groups, and II and DD/DI groups. Exercise training increased significantly and similarly VO(2peak) in homozygous TT and MM/MT individuals, and homozygous II and DD/DI individuals. In addition, exercise training increased significantly LVMI in TT and MM/MT individuals (76.5 +/- 3 vs. 86.7 +/- 4, P=0.00001 and 76.2 +/- 2 vs. 81.4 +/- 2, P=0.00001, respectively), and II and DD/DI individuals (777 +/- 4 vs. 81.5 +/- 4, P=0.0001 and 76 +/- 2 vs. 83.5 +/- 2, P=0.0001, respectively). However, LVMI I in TT individuals was significantly greater than in MM/MT individuals (P=0.04). LVMI was not different between 11 and DD/DI individuals. Conclusion Left-ventricular hypertrophy caused by exercise training is exacerbated in homozygous TT individuals with angiotensinogen polymorphism. Eur J Cardiovasc Prev Rehabil 16:487-492 (C) 2009 The European Society of Cardiology

Effects of creatine supplementation on glucose tolerance and insulin sensitivity in sedentary healthy males undergoing aerobic training

Recent findings have indicated that creatine supplementation may affect glucose metabolism. This study aimed to examine the effects of creatine supplementation, combined with aerobic training, on glucose tolerance in sedentary healthy male. Subjects (n = 22) were randomly divided in two groups and were allocated to receive treatment with either creatine (CT) (similar to 10g .day over three months) or placebo (PT) (dextrose). Administration of treatments was double blind. Both groups underwent moderate aerobic training. An oral glucose tolerance test (OGTT) was performed and both fasting plasma insulin and the homeostasis model assessment (HOMA) index were assessed at the start, and after four, eight and twelve weeks. CT demonstrated significant decrease in OGTT area under the curve compared to PT (P = 0.034). There were no differences between groups or over time in fasting insulin or HOMA. The results suggest that creatine supplementation, combined with aerobic training, can improve glucose tolerance but does not affect insulin sensitivity, and may warrant further investigation with diabetic subjects.

MicroRNAs 29 are involved in the improvement of ventricular compliance promoted by aerobic exercise training in rats

Soci UPR, Fernandes T, Hashimoto NY, Mota GF, Amadeu MA, Rosa KT, Irigoyen MC, Phillips MI, Oliveira EM. MicroRNAs 29 are involved in the improvement of ventricular compliance promoted by aerobic exercise training in rats. Physiol Genomics 43: 665-673, 2011. First published March 29, 2011; doi:10.1152/physiolgenomics.00145.2010.-MiRNAs regulate cardiac development, hypertrophy, and angiogenesis, but their role in cardiac hypertrophy (CH) induced by aerobic training has not previously been studied. Aerobic training promotes physiological CH preserving cardiac function. This study assessed involvement of miRNAs-29 in CH of trained rats. Female Wistar rats (n = 7/group) were randomized into three groups: sedentary (S), training 1 (T1), training 2 (T2). T1: swimming sessions of 60 min/5 days/wk/10 wk. T2: similar to T1 until 8th wk. On the 9th wk rats swam 2x/day, and on the 10th wk 3x/day. MiRNAs analysis was performed by miRNA microarray and confirmed by real-time PCR. We assessed: markers of training, CH by ratio of left ventricle (LV) weight/body wt and cardiomyocytes diameter, pathological markers of CH (ANF, skeletal alpha-actin, alpha/beta-MHC), collagen I and III (COLIAI and COLIIIAI) by real-time PCR, protein collagen by hydroxyproline (OH-proline) concentration, CF and CH by echocardiography. Training improved aerobic capacity and induced CH. MiRNAs-1, 133a, and 133b were downregulated as observed in pathological CH, however, without pathological markers. MiRNA-29c expression increased in T1 (52%) and T2 (123%), correlated with a decrease in COLIAI and COLIIIAI expression in T1 (27%, 38%) and T2 (33%, 48%), respectively. MiRNA-29c was inversely correlated to OH-proline concentration (r = 0.61, P = 0.05). The E/A ratio increased in T2, indicating improved LV compliance. Thus, these results show that aerobic training increase miR-29 expression and decreased collagen gene expression and concentration in the heart, which is relevant to the improved LV compliance and beneficial cardiac effects, associated with aerobic high performance training.

RESPONSES OF HEMATOLOGICAL PARAMETERS AND AEROBIC PERFORMANCE OF ELITE MEN AND WOMEN SWIMMERS DURING A 14-WEEK TRAINING PROGRAM

Santhiago, V, da Silva, ASR, Papoti, M, and Gobatto, CA. Responses of hematological parameters and aerobic performance of elite men and women swimmers during a 14-week training program. J Strength Cond Res 23(4): 1097-1105, 2009-The main purpose of the present investigation was to verify the responses of hematological parameters in men and women competitive swimmers during a 14-week training program. Twenty-three Olympic and international athletes were evaluated 4 times during the experiment: at the beginning of the endurance training phase (T1), at the end of the endurance training phase (T2), at the end of the quality phases (T3), and at the end of the taper period (T4). On the first day at 8:00 AM, each swimmer had a blood sample taken for the determination of hematological parameters. At 3:00 PM, the athletes had their aerobic performance measured by anaerobic threshold. On the second day at 8: 00 AM, the swimmers had their aerobic performance measured by critical velocity. Hematocrit and mean corpuscular volume diminished (p <= 0.05) from T1 to T2 (men: 5.8 and 7.2%; women: 11.6 and 6.8%), and increased (p <= 0.05) from T2 to T3 (men: 7.2 and 6.0%; women: 7.4 and 5.2%). These results were related to the plasma volume changes of the athletes. However, these alterations do not seem to affect the swimmers` aerobic performance. For practical applications, time-trial performance is better than aerobic performance (i.e., anaerobic threshold and critical velocity) for monitoring training adaptations.

Rapid solidification and phase stability evaluation of Ti-Si-B alloys

Ti-rich Ti-Si-B alloys can be considered for structural applications at high temperatures (max. 700 degrees C), however, phase equilibria data is reported only for T = 1250 degrees C. Thus, in this work the phase stability of this system has been evaluated at 700 degrees C. In order to attain equilibrium conditions in shorter time, rapid solidified samples have been prepared and carefully characterized. The microstructural characterization of the produced materials were based on X-ray diffraction (XRD), scanning electron microscopy (SEM-BSE), high resolution transmission electron microscopy (HRTEM), High Temperature X-ray diffraction with Synchrotron radiation (XRDSR) and Differential Scanning Calorimetry (DSC). Amorphous and amorphous with embedded nanocrystals have been observed after rapid solidification from specific alloy compositions. The values of the crystallization temperature (Tx) of the alloys were in the 509-647 degrees C temperature range. After Differential Scanning Calorimetry and High Temperature X-ray Diffraction with Synchrotron radiation, the alloys showed crystalline and basically formed by two or three of the following phases: alpha Ti, Ti(6)Si(2)B; Ti(5)Si(3); Ti(3)Si and TiB. It has been shown the stability of the Ti(3)Si and Ti(6)Si(2)B phases at 700 degrees C and the proposition of an isothermal section at this temperature. (C) 2011 Elsevier B.V. All rights reserved.

Obtaining and stability verification of superconducting phases of the Nb-Al and Nb-Sn systems by mechanical alloying and low-temperature heat treatments

The development of Nb(3)Al and Nb(3)Sn superconductors is of great interest for the applied superconductivity area. These intermetallics composites are obtained normally by heat treatment reactions at high temperature. Processes that allow formation of the superconducting phases at lower temperatures (<1000 degrees C), particularly for Nb(3)Al, are of great interest. The present work studies phase formation and stability of Nb(3)Al and Nb(3)Sn superconducting phases using mechanical alloying (high energy ball milling). Our main objective was to form composites near stoichiometry, which could be transformed into the superconducting phases using low-temperature heat treatments. High purity Nb-Sn and Nb-Al powders were mixed to generate the required superconducting phases (Nb-25at.%Sn and Nb-25at.%Al) in an argon atmosphere glove-box. After milling in a Fritsch mill, the samples were compressed in a hydraulic uniaxial press and encapsulated in evacuated quartz tubes for heat treatment. The compressed and heat treated samples were characterized using X-ray diffractometry. Microstructure and chemical analysis were accomplished using scanning electron microscopy and energy dispersive spectrometry. Nb(3)Al XRD peaks were observed after the sintering at 800 degrees C for the sample milled for 30 h. Nb(3)Sn XRD peaks could be observed even before the heat treatment. (C) 2009 Elsevier B.V. All rights reserved.

Stability region bifurcations of nonlinear autonomous dynamical systems: Type-zero saddle-node bifurcations

The behavior of stability regions of nonlinear autonomous dynamical systems subjected to parameter variation is studied in this paper. In particular, the behavior of stability regions and stability boundaries when the system undergoes a type-zero sadle-node bifurcation on the stability boundary is investigated in this paper. It is shown that the stability regions suffer drastic changes with parameter variation if type-zero saddle-node bifurcations occur on the stability boundary. A complete characterization of these changes in the neighborhood of a type-zero saddle-node bifurcation value is presented in this paper. Copyright (C) 2010 John Wiley & Sons, Ltd.

Multidimensional cluster stability analysis from a Brazilian Bradyrhizobium sp RFLP/PCR data set

The taxonomy of the N(2)-fixing bacteria belonging to the genus Bradyrhizobium is still poorly refined, mainly due to conflicting results obtained by the analysis of the phenotypic and genotypic properties. This paper presents an application of a method aiming at the identification of possible new clusters within a Brazilian collection of 119 Bradryrhizobium strains showing phenotypic characteristics of B. japonicum and B. elkanii. The stability was studied as a function of the number of restriction enzymes used in the RFLP-PCR analysis of three ribosomal regions with three restriction enzymes per region. The method proposed here uses Clustering algorithms with distances calculated by average-linkage clustering. Introducing perturbations using sub-sampling techniques makes the stability analysis. The method showed efficacy in the grouping of the species B. japonicum and B. elkanii. Furthermore, two new clusters were clearly defined, indicating possible new species, and sub-clusters within each detected cluster. (C) 2008 Elsevier B.V. All rights reserved.