Effects of Diets Supplemented with Branched-Chain Amino Acids on the Performance and Fatigue Mechanisms of Rats Submitted to Prolonged Physical Exercise

This study aimed to determine the effects of diets chronically supplemented with branched-chain amino acids (BCAA) on the fatigue mechanisms of trained rats. Thirty-six adult Wistar rats were trained for six weeks. The training protocol consisted of bouts of swimming exercise (one hour a day, five times a week, for six weeks). The animals received a control diet (C) (n = 12), a diet supplemented with 3.57% BCAA (S1) (n = 12), or a diet supplemented with 4.76% BCAA (S2) (n = 12). On the last day of the training protocol, half the animals in each group were sacrificed after one hour of swimming (1H), and the other half after a swimming exhaustion test (EX). Swimming time until exhaustion was increased by 37% in group S1 and reduced by 43% in group S2 compared to group C. Results indicate that the S1 diet had a beneficial effect on performance by sparing glycogen in the soleus muscle (p < 0.05) and by inducing a lower concentration of plasma ammonia, whereas the S2 diet had a negative effect on performance due to hyperammonemia (p < 0.05). The hypothalamic concentration of serotonin was not significantly different between the 1H and EX conditions. In conclusion, chronic BCAA supplementation led to increased performance in rats subjected to a swimming test to exhaustion. However, this is a dose-dependent effect, since chronic ingestion of elevated quantities of BCAA led to a reduction in performance.

Self-Assembly of Poly(4-vynil-N-alkylpyridinium) Bromide onto Silica: Effect of Side-Chain Length on Structural Aspects at a Molecular Level

Self-assembly of poly(4-vynil-N-alkyl)pyridinium bromide with alkyl side chains of 2, 5, 7, 10, or 16 carbons from ethanolic solutions onto flat silica surfaces was studied by means of ellipsometry, atomic force microscopy (AFM), contact angle measurements, and sum-frequency generation (SFG) vibrational spectroscopy in the CH3 and CH2 stretch region. Ab initio quantum-chemical calculations on the N-alkylpyridinium side-group with restricted Hartree-Fock (RHF) method and 6-311G (d,p) basis set were C one to estimate the charge distribution along the pyridinium ring and the alkyl side-chain. SFG results showed that longer side chains promote the disorientation of the alkyl groups at the surface, corroborating with the contact angle values. AFM images revealed film homogeneity, regardless the alkyl side group. However, after 24 h contact with water, ringlike structures appeared on the film surfaces, when the polycation alkyl side chain had 7 or less carbons, and as the alkyl chain increased to 10 or 16 carbons, the films dewetted because the hydrophobic interactions prevailed over the electrostatic interactions between the pyridinium charged groups and the negatively charged SiO2 surface. Under acid conditions (HCl 0.1 mol.L-1), the film mean thickness values decreased up to 50% of original values when the alkyl side chains were ethyl or pentyl groups due to ion-pair disruption, but for longer groups they remained unchanged. Quantum-chemical optimization and Mulliken electron population showed that (i) from C2 to C15 the positive charge at the headgroup (HG) decreased 0.025, while the charge at combined HG + alpha-CH2 increased 0.037; and (ii) for C6 or longer, the alkyl side group presents a tilt in the geometry, moving away from the plane. Such effects summed up over the whole polymer chain give support to suggest that when the side chains are longer than 7 carbons, the hydrophobic interaction decreases film stability and increases acid resistance.

Actinobaculum suis Detection Using Polymerase Chain Reaction

Actinobaculum suis is an important agent related to urinary infection in swine females. Due to its fastidious growth characteristics, the isolation of this anaerobic bacterium is difficult, thus impairing the estimation of its prevalence. The purpose of this study was to develop and test a polymerase chain reaction (PCR) for the detection and identification of A. suis and then compare these results with traditional isolation methods. Bacterial isolation and PCR were performed on one hundred and ninety-two urine samples from sows and forty-five preputial swabs from boars. The results indicate that this PCR was specific for A. suis, presenting a detection limit between 1.0 x 10(1) CFU/mL and 1.0 x 10(2) CFU/mL. A. suis frequencies, as measured by PCR, were 8.9% (17/192) in sow urine samples and 82.2% (37/45) in preputial swabs. Assessed using conventional culturing techniques, none of the urine samples were positive for A. suis; however, A. suis was detected in 31.1% (14/45) of the swabs. This PCR technique was shown to be an efficient method for the detection of A. suis in urine and preputial swabs.

Human Leukocyte Death After a Preoperative Infusion of Medium/Long-Chain Triglyceride and Fish Oil Parenteral Emulsions: A Randomized Study in Gastrointestinal Cancer Patients

Background: Parenteral lipid emulsions (LEs) can influence leukocyte functions. The authors investigated the effect of 2 LEs on leukocyte death in surgical patients with gastrointestinal cancer. Material and Methods: Twenty-five patients from a randomized, double-blind clinical trial (ID: NCT01218841) were randomly included to evaluate leukocyte death after 3 days of preoperative infusion (0.2 g fat/kg/d) of an LE composed equally of medium/long-chain triglycerides and soybean oil (MCTs/LCTs) or pure fish oil (FO). Blood samples were collected before (t0) and after LE infusion (t1) and on the third postoperative day (t2). Results: After LE infusion (t1 vs t0), MCTs/LCTs did not influence cell death; FO slightly increased the proportion of necrotic lymphocytes (5%). At the postoperative period (t2 vs t0), MCTs/LCTs tripled the proportion of apoptotic lymphocytes; FO maintained the slightly increased proportion of necrotic lymphocytes (7%) and reduced the percentage of apoptotic lymphocytes by 74%. In the postoperative period, MCT/LCT emulsion increased the proportion of apoptotic neutrophils, and FO emulsion did not change any parameter of apoptosis in the neutrophil population. There were no differences in lymphocyte or neutrophil death when MCT/LCT and FO treatments were compared during either preoperative or postoperative periods. MCT/LCTs altered the expression of 12 of 108 genes related to cell death, with both pro- and antiapoptotic effects; FO modulated the expression of 7 genes, demonstrating an antiapoptotic effect. Conclusion: In patients with gastrointestinal cancer, preoperative MCT/LCT infusion was associated with postoperative lymphocyte and neutrophil apoptosis. FO has a protective effect on postoperative lymphocyte apoptosis. (JPEN J Parenter Enteral Nutr. 2012; 36: 677-684)

The role of the C-terminal region of pulchellin A-chain in the interaction with membrane model systems

Pulchellin is a Ribosome Inactivating Protein containing an A-chain (PAC), whose toxic activity requires crossing the endoplasmic reticulum (ER) membrane. In this paper, we investigate the interaction between recombinant PAC (rPAC) and Langmuir monolayers of dipalmitoyl phosphatidyl glycerol (DPPG), which served as membrane model. Three catalytically active, truncated PACs with increasing deletion of the C-terminal region, possessing 244,239 and 236 residues (rPAC(244), rPAC(239) and rPAC(236)), were studied. rPAC had the strongest interaction with the DPPG monolayer, inducing a large expansion in its surface pressure-area isotherm. The affinity to DPPG decreased with increased deletion of the C-terminal region. When the C-terminal region was deleted completely (rPAC(236)), the interaction was recovered, probably because other hydrophobic regions were exposed to the membrane. Using Polarization Modulated-Infrared Reflection Absorption Spectroscopy (PM-IRRAS) we observed that at a bare air/water interface rPAC comprised mainly alpha-helix structures, the C-terminal region had unordered structures when interacting with DPPG. For rPAC(236) the alpha-helices were preserved even in the presence of DPPG. These results confirm the importance of the C-terminal region for PAC-ER membrane interaction. The partial unfolding only with preserved C-terminal appears a key step for the protein to reach the cytosol and develop its toxic activity. (C) 2011 Elsevier B.V. All rights reserved.

Side-chain Modifications of Highly Functionalized 3(2H)-Furanones

A series of 3(2H)-furanones, based on side-chain modifications of a parent 3(2H)-furanone, was synthesized in good yield. The parent compound was prepared by hydrogenolysis, and subsequent acid hydrolysis, of isoxazole derivatives. The isoxazole was prepared by a [3+2] 1,3-dipolar cycloaddition reaction between 3-butyn-2-ol and nitrile oxide.

RNA interference-mediated knockdown of CD49e (α5 integrin chain) in human thymic epithelial cells modulates the expression of multiple genes and decreases thymocyte adhesion

Abstract Background The thymus is a central lymphoid organ, in which bone marrow-derived T cell precursors undergo a complex process of maturation. Developing thymocytes interact with thymic microenvironment in a defined spatial order. A component of thymic microenvironment, the thymic epithelial cells, is crucial for the maturation of T-lymphocytes through cell-cell contact, cell matrix interactions and secretory of cytokines/chemokines. There is evidence that extracellular matrix molecules play a fundamental role in guiding differentiating thymocytes in both cortical and medullary regions of the thymic lobules. The interaction between the integrin α5β1 (CD49e/CD29; VLA-5) and fibronectin is relevant for thymocyte adhesion and migration within the thymic tissue. Our previous results have shown that adhesion of thymocytes to cultured TEC line is enhanced in the presence of fibronectin, and can be blocked with anti-VLA-5 antibody. Results Herein, we studied the role of CD49e expressed by the human thymic epithelium. For this purpose we knocked down the CD49e by means of RNA interference. This procedure resulted in the modulation of more than 100 genes, some of them coding for other proteins also involved in adhesion of thymocytes; others related to signaling pathways triggered after integrin activation, or even involved in the control of F-actin stress fiber formation. Functionally, we demonstrated that disruption of VLA-5 in human TEC by CD49e-siRNA-induced gene knockdown decreased the ability of TEC to promote thymocyte adhesion. Such a decrease comprised all CD4/CD8-defined thymocyte subsets. Conclusion Conceptually, our findings unravel the complexity of gene regulation, as regards key genes involved in the heterocellular cell adhesion between developing thymocytes and the major component of the thymic microenvironment, an interaction that is a mandatory event for proper intrathymic T cell differentiation.

Potential therapeutic effects of branched-chain amino acids supplementation on resistance exercise-based muscle damage in humans

Branched-chain amino acids (BCAA) supplementation has been considered an interesting nutritional strategy to improve skeletal muscle protein turnover in several conditions. In this context, there is evidence that resistance exercise (RE)-derived biochemical markers of muscle soreness (creatine kinase (CK), aldolase, myoglobin), soreness, and functional strength may be modulated by BCAA supplementation in order to favor of muscle adaptation. However, few studies have investigated such effects in well-controlled conditions in humans. Therefore, the aim of this short report is to describe the potential therapeutic effects of BCAA supplementation on RE-based muscle damage in humans. The main point is that BCAA supplementation may decrease some biochemical markers related with muscle soreness but this does not necessarily reflect on muscle functionality.

Diet-Sensitive Sources of Reactive Oxygen Species in Liver Mitochondria: Role of Very Long Chain Acyl-CoA Dehydrogenases

High fat diets and accompanying hepatic steatosis are highly prevalent conditions. Previous work has shown that steatosis is accompanied by enhanced generation of reactive oxygen species (ROS), which may mediate further liver damage. Here we investigated mechanisms leading to enhanced ROS generation following high fat diets (HFD). We found that mitochondria from HFD livers present no differences in maximal respiratory rates and coupling, but generate more ROS specifically when fatty acids are used as substrates. Indeed, many acyl-CoA dehydrogenase isoforms were found to be more highly expressed in HFD livers, although only the very long chain acyl-CoA dehydrogenase (VLCAD) was more functionally active. Studies conducted with permeabilized mitochondria and different chain length acyl-CoA derivatives suggest that VLCAD is also a source of ROS production in mitochondria of HFD animals. This production is stimulated by the lack of NAD+. Overall, our studies uncover VLCAD as a novel, diet-sensitive, source of mitochondrial ROS.

Chain extension of poly (ethylene terephthalate) by reactive extrusion with secondary stabilizer

Poly(ethylene tereftalate) (PET) is a polymer highly susceptible to the hydrolytic reactions that occur during applications and mainly in thermomechanical processing. These reactions lead to the decrease of molecular weight of the polymer, limiting the recycling number of the material. The reactive extrusion of the PET in presence of chain extenders is an alternative to recover mechanical and rheological properties that were depreciated by the polymer degradation. In this study, PET wastes from nonwoven fabrics production were extruded in presence of the secondary stabilizer Irgafos 126 (IRG) on variable concentrations. The results showed that Irgafos 126 increased molecular weight, decreased crystallinity and changed processing behavior of the PET, similarly to the effects produced by the well-known chain extender pyromellitic dianhydride (PMDA), showing that the secondary stabilizer Irgafos 126 can also act as a chain extender for the PET.

Fourier´s law from a chain of coupled anharmonic oscillators under energy conserving shot noise.

We analyze the transport of heat along a chain of particles interacting through anharmonic potentials consisting of quartic terms in addition to harmonic quadratic terms and subject to heat reservoirs at its ends. Each particle is also subject to an impulsive shot noise with exponentially distributed waiting times whose effect is to change the sign of its velocity, thus conserving the energy of the chain. We show that the introduction of this energy conserving stochastic noise leads to Fourier's law. That is for large system size L the heat current J behaves as J ‘approximately’ 1/L, which amounts to say that the conductivity k is constant. The conductivity is related to the current by J = kΔT/L, where ΔT is the difference in the temperatures of the reservoirs. The behavior of heat conductivity k for small intensities¸ of the shot noise and large system sizes L are obtained by assuming a scaling behavior of the type k = ‘L POT a Psi’(L’lambda POT a/b’) where a and b are scaling exponents. For the pure harmonic case a = b = 1, characterizing a ballistic conduction of heat when the shot noise is absent. For the anharmonic case we found values for the exponents a and b smaller then 1 and thus consistent with a superdiffusive conduction of heat without the shot noise. We also show that the heat conductivity is not constant but is an increasing function of temperature.

Heat conduction in a chain of harmonic and anharmonic oscillators under the presence of an energy conserving noise

Reproducing Fourier's law of heat conduction from a microscopic stochastic model is a long standing challenge in statistical physics. As was shown by Rieder, Lebowitz and Lieb many years ago, a chain of harmonically coupled oscillators connected to two heat baths at different temperatures does not reproduce the diffusive behaviour of Fourier's law, but instead a ballistic one with an infinite thermal conductivity. Since then, there has been a substantial effort from the scientific community in identifying the key mechanism necessary to reproduce such diffusivity, which usually revolved around anharmonicity and the effect of impurities. Recently, it was shown by Dhar, Venkateshan and Lebowitz that Fourier's law can be recovered by introducing an energy conserving noise, whose role is to simulate the elastic collisions between the atoms and other microscopic degrees of freedom, which one would expect to be present in a real solid. For a one-dimensional chain this is accomplished numerically by randomly flipping - under the framework of a Poisson process with a variable “rate of collisions" - the sign of the velocity of an oscillator. In this poster we present Langevin simulations of a one-dimensional chain of oscillators coupled to two heat baths at different temperatures. We consider both harmonic and anharmonic (quartic) interactions, which are studied with and without the energy conserving noise. With these results we are able to map in detail how the heat conductivity k is influenced by both anharmonicity and the energy conserving noise. We also present a detailed analysis of the behaviour of k as a function of the size of the system and the rate of collisions, which includes a finite-size scaling method that enables us to extract the relevant critical exponents. Finally, we show that for harmonic chains, k is independent of temperature, both with and without the noise. Conversely, for anharmonic chains we find that k increases roughly linearly with the temperature of a given reservoir, while keeping the temperature difference fixed.