86 research outputs found
High-intensity exercise training enhances mitochondrial oxidative phosphorylation efficiency in a temperature-dependent manner in human skeletal muscle: implications for exercise performance
No full textThe purpose of the present study was to investigate whether exercise training-induced adaptations in human skeletal muscle mitochondrial bioenergetics are magnified under thermal conditions resembling sustained intense contractile activity and whether training-induced changes in mitochondrial oxidative phosphorylation (OXPHOS) efficiency influence exercise efficiency. Twenty healthy men performed 6 wk of high-intensity exercise training [i.e., speed endurance training (SET; n = 10)], or maintained their usual lifestyle (CON; n = 10). Before and after the intervention, mitochondrial respiratory function was determined ex vivo in permeabilized muscle fibers under experimentally-induced normothermia (35°C) and hyperthermia (40°C) mimicking in vivo muscle temperature at rest and during intense exercise, respectively. In addition, activity and content of muscle mitochondrial enzymes and proteins were quantified. Exercising muscle efficiency was determined in vivo by measurements of leg hemodynamics and blood parameters during one-legged knee-extensor exercise. SET enhanced maximal OXPHOS capacity and OXPHOS efficiency at 40°C, but not at 35°C, and attenuated hyperthermia-induced decline in OXPHOS efficiency. Furthermore, SET increased expression of markers of mitochondrial content and up-regulated content of MFN2, DRP1, and ANT1. Also, SET improved exercise efficiency and capacity. These findings indicate that muscle mitochondrial bioenergetics adapts to high-intensity exercise training in a temperature-dependent manner and that enhancements in mitochondrial OXPHOS efficiency may contribute to improving exercise performance.-Fiorenza, M., Lemminger, A. K., Marker, M., Eibye, K., Iaia, F. M., Bangsbo, J., Hostrup, M. High-intensity exercise training enhances mitochondrial oxidative phosphorylation efficiency in a temperature-dependent manner in human skeletal muscle: implications for exercise performance
Metabolic stress-dependent regulation of the mitochondrial biogenic molecular response to high-intensity exercise in human skeletal muscle
No full textKEY POINTS: Low-volume high-intensity exercise training promotes muscle mitochondrial adaptations that resemble the ones associated with high-volume moderate-intensity exercise training. These training-induced mitochondrial adaptations stem from the cumulative effects of transient transcriptional responses to each acute exercise bout. However, whether metabolic stress is a key mediator of the acute molecular responses to high-intensity exercise is still incompletely understood. Herein we show that, by comparing different work-matched low-volume high-intensity exercise protocols, more marked metabolic perturbations were associated with enhanced mitochondrial biogenesis-related muscle mRNA responses. Furthermore, when compared with high-volume moderate-intensity exercise, only the low-volume high-intensity exercise eliciting severe metabolic stress compensated for reduced exercise volume in the induction of mitochondrial biogenic mRNA responses. The present results, besides improving our understanding of the mechanisms mediating exercise-induced mitochondrial biogenesis, may have implications for applied and clinical research that adopts exercise as a means to increase muscle mitochondrial content and function in healthy or diseased individuals. ABSTRACT: The aim of the present study was to examine the impact of exercise-induced metabolic stress on regulation of the molecular responses promoting skeletal muscle mitochondrial biogenesis. Twelve endurance-trained men performed three cycling-exercise protocols characterized by different metabolic profiles in a randomized, counter-balanced order. Specifically, two work-matched low-volume supramaximal-intensity intermittent regimes, consisting of repeated-sprint (RS) and speed endurance (SE) exercise, were employed and compared with a high-volume continuous moderate-intensity exercise (CM) protocol. Vastus lateralis muscle samples were obtained before, immediately after, and 3h after exercise. SE produced the most marked metabolic perturbations as evidenced by the greatest changes in muscle lactate and pH, concomitantly with higher post-exercise plasma adrenaline levels in comparison with RS and CM (P < 0.05). Exercise-induced phosphorylation of CaMKII and p38 MAPK was greater in SE than in RS and CM. The exercise-induced PGC-1α mRNA response was higher in SE and CM than in RS, with no difference between SE and CM. Muscle NRF-2, TFAM, MFN2, DRP1 and SOD2 mRNA content was elevated to the same extent by SE and CM, while RS had no effect on these mRNAs. The exercise-induced HSP72 mRNA response was larger in SE than in RS and CM. Thus, the present results suggest that, for a given exercise volume, the initial events associated with mitochondrial biogenesis are modulated by metabolic stress. In addition, high-intensity exercise seems to compensate for reduced exercise volume in the induction of mitochondrial biogenic molecular responses only when the intense exercise elicits marked metabolic perturbations. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved
Apparatus and method for obtaining a core at in situ pressure
No full textA method and apparatus are disclosed for obtaining a core at in situ pressure of sedimentary deposits at the bottom of a well bore or body of water. The core barrel has a pressure chamber that is closed and opened by a ball valve actuated from the surface. When in position above the sedimentary deposits to be cored, a sample tube is extended from the pressure chamber into the sedimentary deposits to obtain a core. The sample tube is retracted into the pressure chamber and the valve closed to trap ambient pressure in the chamber. The sample tube and valve are operated from the surface.U
Neuromuscular fatigue and metabolism during high-intensity intermittent exercise
No full textPURPOSE: To examine the degree of neuromuscular fatigue development along with changes in muscle metabolism during two work-matched high-intensity intermittent exercise protocols in trained individuals. METHODS: In a randomized, counter-balanced, crossover design, eleven endurance-trained men performed high-intensity intermittent cycle exercise protocols matched for total work and including either multiple short- (18×5 s; SS) or long-duration (6×20 s; LS) sprints. Neuromuscular fatigue was determined by pre- to post-exercise changes in maximal voluntary contraction force (MVC), voluntary activation level and contractile properties of the quadriceps muscle. Metabolites and pH were measured in vastus lateralis muscle biopsies taken before and after the first and last sprint of each exercise protocol. RESULTS: Peak power output (11±2 vs. 16±8%, P<0.01), MVC (10±5 vs. 25±6%, P<0.05) and peak twitch force (34±5 vs. 67±5 %, P<0.01) declined to a lesser extent in SS than LS, while voluntary activation level decreased similarly in SS and LS (10±2 vs. 11±4%). Muscle [PCr] prior to the last sprint was 1.5-fold lower in SS than LS (P<0.001). Pre- to post-exercise intramuscular accumulation of lactate and H was two- and three-fold lower, respectively, in SS than LS (P<0.001), whereas muscle glycogen depletion was similar in SS and LS. Rate of muscle glycolysis was similar in SS and LS during the first sprint, but two-fold higher in SS than LS during the last sprint (P<0.05). CONCLUSION: These findings indicate that, in endurance-trained individuals, multiple long-sprints induce larger impairments in performance along with greater degrees of peripheral fatigue compared to work-matched multiple short-sprints, with these differences being possibly attributed to more extensive intramuscular accumulation of lactate/H and to lower rates of glycolysis during multiple long-sprint exercise
Long-Acting β2-Agonists in Asthma: Enantioselective Safety Studies are Needed
No full textLong-acting β2-agonists (LABAs) such as formoterol and salmeterol are used for prolonged bronchodilatation in asthma, usually in combination with inhaled corticosteroids (ICSs). Unexplained paradoxical asthma exacerbations and deaths have been associated with LABAs, particularly when used without ICS. LABAs clearly demonstrate effective bronchodilatation and steroid-sparing activity, but long-term treatment can lead to tolerance of their bronchodilator effects. There are also concerns with regard to the effects of LABAs on bronchial hyperresponsiveness (BHR), where long-term use is associated with increased BHR and loss of bronchoprotection. A complicating factor is that formoterol and salmeterol are both chiral compounds, usually administered as 50:50 racemic (rac-) mixtures of two enantiomers. The chiral nature of these compounds has been largely forgotten in the debate regarding LABA safety and effects on BHR, particularly that (S)-enantiomers of β2-agonists may be deleterious to asthma control. LABAs display enantioselective pharmacokinetics and pharmacodynamics. Biological plausibility of the deleterious effects of β2-agonists (S)-enantiomers is provided by in vitro and in vivo studies from the short-acting β2-agonist (SABA) salbutamol. Supportive clinical findings include the fact that patients in emergency departments who demonstrate a blunted response to salbutamol are more likely to benefit from (R)-salbutamol than rac-salbutamol, and resistance to salbutamol appears to be a contributory mechanism in rapid asthma deaths. More effort should therefore be applied to investigating potential enantiospecific effects of LABAs on safety, specifically bronchoprotection. Safety studies directly assessing the effects of LABA (S)-enantiomers on BHR are long overdue.</p
De emendatione aliquot locorum orationis Tullianae Pro M. Caelio disputationis part I [microform] /
No full textFilmed with: Malinin, Alexander / Hat Dörpfeld die Enneakrunos-episode bei Pausanias tatsächlich gelöst oder auf welchem Wege kann diese gelöst werden? : einige Bemerkungen zu Judeichs "Topographie von Athen" -- Meeks, R. Eduardson / De poesi Graecorum satyrica -- Maisel, Joannes / Observationes in Cassium Dionem -- Mayer, Maximilian / De Euripidis mythopoeia capita duo -- Mavrokordatos, Nektarios / Der Monotheismus des Xenophanes -- May, Oswald / De attractionis usu Herodoteo -- Matter, Jacob / De principiis rationum philosophicarum Pythagorae, Platonis atque Plotini, inter se comparatum -- Mayer, Philipp / Beiträge zu einer homerischen Synonymik -- Mayer, Philipp / Quaestionum Homericarum Part III : de Tiresiae Vaticinatione, quae est in Od. lib. XI, v. 119-137 -- Mayer, Philipp / Ueber den Charakter des Kreon in den beiden Oedipen des Sophokles : erste Abtheilung -- Madvig, J.N. / Disputatio de aliquot lacunis codicum Lucretii -- Madvig, J.N. / De locis quibusdam grammaticae Latinae admonitiones et observationes -- Madvig, J.N. / De L. Attii didascalicis -- Mayer, Philipp / Quaestionum Homericarum part IV : in qua agitur de verbi phrazein vi atque significatione -- Mang, Anton / De attica eloquentia -- Mang, Anton / Das erste Buch der Aristotelischen Topik -- Man, Guillelmus de / Disputatio juridica inauguralis ad Orationem M. Tullii Ciceronis pro Cn. Plancio -- Anton, A.F.M. / Num ad veritatem Tacitus in Ann. I. et II. narravit de expeditionibus Germanici -- Mähly, J. / De Drusi atque Maecenatis epicediis deque Taciteo dialogo criticae -- May, Karl / De ratione et via artis criticae quam inde ab Hofmanno Peerlcampio recentiores editores in recensendis Horatii carminibus inierint -- Mayser, Edwin / Grammatik der griechischen Papyri aus der Ptolimäerzeit : I. Teil -- Matschky, Theodor / Bemerkungen zur Lektüre des Horaz -- Macke, Reinhold / Die römischen Eigennamen bei Tacitus I -- Macke, Reinhold / Die römischen Eigennamen bei Tacitus II.Includes bibliographical references.Microfilm.Mode of access: Internet
Ecological Factors Affecting Hispanic Urban Middle School and High School Adolescents��� College and Career Aspirations
No full textThis mixed methods study investigates how ecological factors influence the
decisions urban Hispanic middle school and high school adolescents make concerning
their college and career aspirations. I examine the academic aspirations, career
aspirations, the influence of peers, teachers, and parents of seventh-, eighth-, ninth-, and
tenth-grade urban Hispanic adolescents, and gender roles in college and career aspirations
through the lens of Bronfenbrenner���s ecological subsystems theory.
Participants took the Student Career Assessment (SCA) survey consisting of
Likert-type multiple choice questions and open-ended questions to assess their college
and career aspirations. Quantitatively analyzed data examined the extent urban Hispanic
middle school and high school adolescents were influenced by items on scales of
encouragement, literacy, and education and whether there were differences by gender and
grade level. Student responses as to why they chose a specific career were analyzed
qualitatively.
Combined results for urban Hispanic middle school and high school adolescents
show a) both genders are interested in finishing high school and going to college, b)
Hispanic females are encouraged more than males to pursue their college and career
aspirations, c) more females than males know their career aspiration, but the majority of
students do not know how to prepare for their chosen career, e) females have more
confidence in their literacy skills than males. The more confidence Hispanic high school
students have in their literacy skills, the more likely they are to graduate from high
school.
Implications for future research should involve conducting studies in the areas of
college and career aspirations of urban Hispanic adolescents using random sampling.
More gender studies involving the college and career aspirations of urban Hispanic
adolescents would significantly add to the current body of knowledge
Deep muscle-proteomic analysis of freeze-dried human muscle biopsies reveals fiber type-specific adaptations to exercise training
No full textSkeletal muscle conveys several of the health-promoting effects of exercise; yet the underlying mechanisms are not fully elucidated. Studying skeletal muscle is challenging due to its different fiber types and the presence of non-muscle cells. This can be circumvented by isolation of single muscle fibers. Here, we develop a workflow enabling proteomics analysis of pools of isolated muscle fibers from freeze-dried human muscle biopsies. We identify more than 4000 proteins in slow- and fast-twitch muscle fibers. Exercise training alters expression of 237 and 172 proteins in slow- and fast-twitch muscle fibers, respectively. Interestingly, expression levels of secreted proteins and proteins involved in transcription, mitochondrial metabolism, Ca2+ signaling, and fat and glucose metabolism adapts to training in a fiber type-specific manner. Our data provide a resource to elucidate molecular mechanisms underlying muscle function and health, and our workflow allows fiber type-specific proteo..
Application of IBM Watson to support literature reviews: A preliminary experience in restorative dentistry
No full textLiterature reviews are crucial in the choice of the best personalized material type and restauration type in restorative dentistry. We developed an IBM-Watson based system to support literature search for restorative dentistry, and compared its results to a literature search performed by a trained professional. We found that our system could assist the researcher in performing a literature review, but the grounding semantic model needs to be refined in order to provide more extensive results
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