2,709 research outputs found
Murine myoblast migration: influence of replicative ageing and nutrition
Cell migration is central to skeletal muscle repair following damage. Leucine and Ī²-Hydroxy Ī²-methylbutyric acid (HMB) are supplements consumed for recovery from muscle damaging exercise in humans, however, their impact on muscle cell migration with age is not yet understood. We hypothesised that replicatively aged (āagedā; P46āP48) myoblasts would be less efficient at basal and supplemented repair versus parental controls (ācontrolā; P12āP16). Aged and control myoblasts were scratch-damaged and migration velocity, directionality and distance assessed over 48 h in the absence and presence of leucine (10 mM) or HMB (10 mM) Ā± PI3K/Akt (LY294002 10 Ī¼M), ERK (PD98059 5 Ī¼M) or mTOR (rapamycin 0.5 Ī¼M) inhibition. Opposing our hypothesis, aged cells displayed increased velocities, directionality and distance migrated (P < 0.001) versus control. Leucine and HMB significantly increased (P < 0.001) the same parameters in control cells. The supplements were with smaller, albeit significant impact on aged cell velocity (P < 0.001) and in the presence of HMB only, distance (P = 0.041). Inhibitor studies revealed that, PI3K and ERK activation were essential for velocity, directionality and migration distance of aged cells in basal conditions, whereas mTOR was important for directionality only. While PI3K activation was critical for all parameters in control cells (P < 0.001), inhibition of ERK or mTOR improved, rather than reduced, control cell migration distance. Enhanced basal velocity, directionality and distance in aged cells required ERK and PI3K activation. By contrast, in control cells, basal migration was underpinned by PI3K activation, and facilitated by leucine or HMB supplementation, to migration levels seen in aged cells. These data suggest that replicatively aged myoblasts are not anabolically resistant per se, but are capable of efficient repair, underpinned by altered signaling pathways, compared with unaged control myoblasts
Segregating the Distinct Effects of Sedentary Behavior and Physical Activity on Older Adults' Cardiovascular Profile: Part 2-Isotemporal Substitution Approach.
The aim of the study was to provide an isotemporal substitution model to predict how changes in physical behavior may affect the cardiovascular parameters (CVPs) of older adults. Methods: Participants wore a thigh-mounted accelerometer for 7 days. Phenotype of the carotid, brachial, and popliteal artery was conducted using ultrasound. Isotemporal substitution was used to simulate the degree to which replacing 1 hour of physical behavior with another would affect CVP. Results: Substitution of sedentary behavior with Standing and sporadic moderate- to vigorous-intensity physical activity (MVPA accumulated in bouts <10 min) would reduce resting heart rate [ā6.20 beats per minute (ā12.1 to ā0.22) and ā3.72 beats per minute (ā7.01 to ā0.44), respectively]. Substitution of sedentary behavior with light-intensity physical activity would reduce carotid artery diameter [ā0.54 mm (ā1.00 to ā0.07)]. Substitution of Standing with sporadic MVPA would increase popliteal artery diameter [1.31 mm (0.11 to 2.51)]. Conclusions: Our modeling suggests that an accumulation of MVPA bouts that are shorter than the recommended 10-minute minimum may still improve CVP, with lower intensity physical activity also influencing CVP. Our findings are a promising avenue for lifestyle interventions in older adults to reduce the aging effects on CVP for those who cannot engage or sustain sufficient MVPA
Implementing One Health approaches to Emerging Infectious Disease: Reflections on the socio-political, ethical and legal dimensions
Background: āOne Healthā represents a call for health researchers and practitioners at the human, animal and
environmental interfaces to work together to mitigate the risks of emerging and re-emerging infectious diseases
(EIDs). A One Health approach emphasizing inter-disciplinary co-operation is increasingly seen as necessary for
effective EID control and prevention. There are, however, socio-political, ethical and legal challenges, which must be
met by such a One Health approach.
Discussion: Based on the philosophical review and critical analysis of scholarship around the theory and practice of
One Health it is clear that EID events are not simply about pathogens jumping species barriers; they are comprised
of complex and contingent sets of relations that involve socioeconomic and socio-political drivers and
consequences with the latter extending beyond the impact of the disease. Therefore, the effectiveness of policies
based on One Health depends on their implementation and alignment with or modification of public values.
Summary: Despite its strong motivating rationale, implementing a One Health approach in an integrated and
considered manner can be challenging, especially in the face of a perceived crisis. The effective control and
prevention of EIDs therefore requires: (i) social science research to improve understanding of how EID threats and
responses play out; (ii) the development of an analytic framework that catalogues case experiences with EIDs,
reflects their dynamic nature and promotes inter-sectoral collaboration and knowledge synthesis; (iii) genuine
public engagement processes that promote transparency, education and capture peopleās preferences; (iv) a set of
practical principles and values that integrate ethics into decision-making procedures, against which policies and
public health responses can be assessed; (v) integration of the analytic framework and the statement of principles
and values outlined above; and (vi) a focus on genuine reform rather than rhetoric.
Keywords: One health, Emerging infectious disease, Zoonoses, Bioethics, Health policy, Health lawThe work was funded by NHMRC grant #1083079 and seed funding from
the Marie Bashir Institute for Infectious Disease and Biosecurity and the
School of Public Health at the University of Sydney
Implementing One Health approaches to Emerging Infectious Disease: Reflections on the socio-political, ethical and legal dimensions
Background: āOne Healthā represents a call for health researchers and practitioners at the human, animal and environmental interfaces to work together to mitigate the risks of emerging and re-emerging infectious diseases (EIDs). A One Health approach emphasizing inter-disciplinary co-operation is increasingly seen as necessary for effective EID control and prevention. There are, however, socio-political, ethical and legal challenges, which must be met by such a One Health approach. Discussion: Based on the philosophical review and critical analysis of scholarship around the theory and practice of One Health it is clear that EID events are not simply about pathogens jumping species barriers; they are comprised of complex and contingent sets of relations that involve socioeconomic and socio-political drivers and consequences with the latter extending beyond the impact of the disease. Therefore, the effectiveness of policies based on One Health depends on their implementation and alignment with or modification of public values. Summary: Despite its strong motivating rationale, implementing a One Health approach in an integrated and considered manner can be challenging, especially in the face of a perceived crisis. The effective control and prevention of EIDs therefore requires: (i) social science research to improve understanding of how EID threats and responses play out; (ii) the development of an analytic framework that catalogues case experiences with EIDs, reflects their dynamic nature and promotes inter-sectoral collaboration and knowledge synthesis; (iii) genuine public engagement processes that promote transparency, education and capture peopleās preferences; (iv) a set of practical principles and values that integrate ethics into decision-making procedures, against which policies and public health responses can be assessed; (v) integration of the analytic framework and the statement of principles and values outlined above; and (vi) a focus on genuine reform rather than rhetoric. Keywords: One health, Emerging infectious disease, Zoonoses, Bioethics, Health policy, Health lawThe work was funded by NHMRC grant #1083079 and seed funding from the Marie Bashir Institute for Infectious Disease and Biosecurity and the School of Public Health at the University of Sydney
Influences of carbohydrate plus amino acid supplementation on differing exercise intensity adaptations in older persons: skeletal muscle and endocrine responses
Losses in physiological function in healthy ageing occur partly as a consequence of reduced protein intake and partly as a consequence of less than 30-min/day of moderate to vigorous physical activity. The current study aimed to compare the effects of two different intensities of resistance training in healthy older adults, whose habitual dietary intake was supplemented with carbohydrate and amino acid preparations. We hypothesised that although intensive exercise with appropriate carbohydrate and amino acid supplementation would result in the most profound impact on in vivo markers of healthy physiologic and endocrine functions in previously sedentary older individuals, the effectiveness of the less intense exercise prescription with supplementation would also result in beneficial adaptations over and above findings of previous studies on low intensity exercise alone. Twenty-nine older adults (out of 32) completed the study after being randomly assigned to low (SUP-LowR, i.e., ā¼40% 1RM; n=16) versus high resistance training (SUP-HighR, i.e., ā¼80% 1RM; n=13) for 12 weeks. A carbohydrate supplement was ingested immediately before and during every exercise session and an amino acid cocktail was ingested post-exercise. Neither intervention significantly impacted upon body composition assessed using: Body mass index, waist/hip ratio and bioelectric impedance. Muscle strength increased similarly in the two groups with the SUP-HighR protocol showing 46Ā±8%, 10.8Ā±4.4% and 26.9Ā± 4.9% (P<0.01) improvements in 1-RM strength, unilateral and bilateral knee extension torque, respectively, compared with 39Ā±2%, 9.4Ā±3.7% and 29.5Ā± 8.2% (P<0.01) increments in the same measures in the SUP-LowR group. Lean muscle thickness however, showed a greater benefit of the SUP-LowR protocol (8.7Ā±3.9% increase, P<0.05) compared with the SUP-HighR protocol, which elicited no significant change. In terms of functional abilities, only the standing-from-lying (SFL) test exhibited an improvement in rate in the SUP-HighR group (-11.4%, P< 0.05). The SUP-LowR group, on the other hand, showed significant improvements in the get-up-andgo (-8.7Ā±3.6%, P<0.05), the SFL (-4.7% change, P=0.05) and the 6-min walk (7.2Ā±2.2% increase in distance covered, P<0.01) tests. Following overnight fasting, serum levels of glucose changed significantly (-13Ā±4.7% decrease, P<0.01) in SUP-LowR. Serum levels of insulin (-25Ā±5.3% decrease, P=0.05), neuropeptide Y (-24Ā±15.3% decrease, P=0.02), and IGFBP-3 (-11Ā±6.6% decrease, P=0.03), changed significantly in SUP-HighR. Circulating levels of interleukin-6, tumour necrosis factor-alpha and insulin- like growth factor 1 did not alter significantly in either intervention group. These data suggest that whilst both interventions were beneficial in older persons, the end targets as well as metabolic and hormonal adaptations are different. The supplementation plus low exercise regimen tended to impact on muscle hypertrophy combined with increased habitual function. Supplementation plus high-intensity exercise regimen improved markers of strength, but not to a significantly greater extent than supplementation plus low intensity exercise. Ā© American Aging Association 2010
Daily Changes of Resting Metabolic Rate in Elite Rugby Union Players
Introduction: Preparation for competitive contact sport has been extensively researched. There are, however, limited data to guide players as to how the demands of their sport affect the energy requirements of recovery. We aimed to provide novel data on changes in resting metabolic rate (RMR) in contact sport athletes and relate these to the physical demands of training and competition.
Methods: Twenty-two elite professional Premiership Rugby Union players were recruited to the study. Indirect calorimetry (Vyntus CPX canopy; CareFusion) was used to measure RMR each morning of the competitive game week, in a fasted, rested state. External loads for training and game play were monitored and recorded using global positioning systems (Catapult Innovations, Australia), whereas internal loads were tracked using rate of perceived exertion scales. Collisions were reviewed and recorded by expert video analysts for contacts in general play (breakdown and tackle area) or the set piece (scrum or maul).
Results: There were significant (P = 0.005) mean increases in RMR of approximately 231 kcal the morning after (game day [GD] + 1) and 3 d after the game (GD + 3), compared with the day before the game (GD ā 1). The players were exposed to internal and external loads during the training week comparable to that of a match day; however, despite the equivocal loads between training and game play, there were no significant increases in RMR after training.
Conclusion: The collisions experienced in rugby match play are likely to be responsible for the significant increases in RMR at GD + 1 and GD + 3. Consequently, the measurement of RMR via indirect calorimetry may provide a novel noninvasive measure of the effects of collisions. This study provides a novel insight to the energy requirements of recovering from contact sport
Avalanches in self-organized critical neural networks: A minimal model for the neural SOC universality class
The brain keeps its overall dynamics in a corridor of intermediate activity
and it has been a long standing question what possible mechanism could achieve
this task. Mechanisms from the field of statistical physics have long been
suggesting that this homeostasis of brain activity could occur even without a
central regulator, via self-organization on the level of neurons and their
interactions, alone. Such physical mechanisms from the class of self-organized
criticality exhibit characteristic dynamical signatures, similar to seismic
activity related to earthquakes. Measurements of cortex rest activity showed
first signs of dynamical signatures potentially pointing to self-organized
critical dynamics in the brain. Indeed, recent more accurate measurements
allowed for a detailed comparison with scaling theory of non-equilibrium
critical phenomena, proving the existence of criticality in cortex dynamics. We
here compare this new evaluation of cortex activity data to the predictions of
the earliest physics spin model of self-organized critical neural networks. We
find that the model matches with the recent experimental data and its
interpretation in terms of dynamical signatures for criticality in the brain.
The combination of signatures for criticality, power law distributions of
avalanche sizes and durations, as well as a specific scaling relationship
between anomalous exponents, defines a universality class characteristic of the
particular critical phenomenon observed in the neural experiments. The spin
model is a candidate for a minimal model of a self-organized critical adaptive
network for the universality class of neural criticality. As a prototype model,
it provides the background for models that include more biological details, yet
share the same universality class characteristic of the homeostasis of activity
in the brain.Comment: 17 pages, 5 figure
"Fuel for the Damage Induced": Untargeted Metabolomics in Elite Rugby Union Match Play.
The metabolic perturbations caused by competitive rugby are not well characterized. Our aim is to utilize untargeted metabolomics to develop appropriate interventions, based on the metabolic fluctuations that occur in response to this collision-based team sport. Seven members of an English Premiership rugby squad consented to provide blood, urine, and saliva samples daily, over a competitive week including gameday (GD), with physical demands and dietary intake also recorded. Sample collection, processing and statistical analysis were performed in accordance with best practice set out by the metabolomics standards initiative employing 700 MHz NMR spectroscopy. Univariate and multivariate statistical analysis were employed to reveal the acute energy needs of this high intensity sport are met via glycolysis, the TCA cycle and gluconeogenesis. The recovery period after cessation of match play and prior to training recommencing sees a re-entry to gluconeogenesis, coupled with markers of oxidative stress, structural protein degradation, and reduced fatty acid metabolism. This novel insight leads us to propose that effective recovery from muscle damaging collisions is dependent upon the availability of glucose. An adjustment in the periodisation of carbohydrate to increase GD+1 provision may prevent the oxidation of amino acids which may also be crucial to allay markers of structural tissue degradation. Should we expand the 'Fuel for the work required' paradigm in collision-based team sports to include 'Fuel for the damage induced'
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Comparative prebiotic activity of mixtures of cereal grain polysaccharides
The main components of the non-starch polysaccharide (NSP) fraction of wheat flour are arabinoxylan (AX) and Ī²-glucan. These are also present in other cereal grains, but their proportions vary with AX being the major component in wheat and rye and Ī²-glucan in barley and oats. Therefore, it was hypothesised that these NSPs could act synergistically when fermented in vitro at the ratios present in the major foods consumed, resulting in increased prebiotic activity. AX and Ī²-glucan were therefore tested in in vitro fermentation studies to assess their prebiotic activity when used individually and/or in different ratios. Short-chain fatty-acids (SCFAs) produced from in vitro fermentation were measured using HPLC and bacterial populations were measured using flow cytometry with fluorescence in situ hybridisation (Flow-FISH). Fermentation of AX alone resulted in a significant bifidogenic activity and increased concentrations of SCFAs, mainly acetate, after 8-24Ā h of fermentation, however Ī²-glucan alone did not show prebiotic activity. The greatest prebiotic activity, based on concentration of total SCFAs and increases in total bacteria as well as beneficial Bifidobacterium and Clostridium coccoides/Eubacterium groups, was observed when AX and Ī²-glucan were combined at a 3:1 ratio, which corresponds to their ratios in wheat flour which is major source of cereal fibre in the diet. This indicates that the population of bacteria in the human GI tract may be modulated by the composition of the fibre in the diet, to maximise the prebiotic potential
Trichinella inflammatory myopathy: host or parasite strategy?
The parasitic nematode Trichinella has a special relation with muscle, because of its unique intracellular localization in the skeletal muscle cell, completely devoted in morphology and biochemistry to become the parasite protective niche, otherwise called the nurse cell. The long-lasting muscle infection of Trichinella exhibits a strong interplay with the host immune response, mainly characterized by a Th2 phenotype
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