| 1. |
- Montiel Rojas, Diego, 1984-, et al.
(författare)
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Short Telomere Length Is Related to Limitations in Physical Function in Elderly European Adults
- 2018
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Ingår i: Frontiers in Physiology. - : Frontiers Media S.A.. - 1664-042X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- The present study aims to explore the potential influence of leucocyte telomere length (LTL) on both a single indicator and a composite construct of physical functioning in a large European population of elderly men and women across diverse geographical locations. A total of 1,221 adults (65-79 years) were recruited from five European countries within the framework of NU-AGE study. The physical functioning construct was based on the 36-item Short Form Health Survey. Handgrip strength was used as a single indicator of muscle function and LTL was assessed using quantitative real-time PCR. Women had significantly longer (p < 0.05) LTL than men. Participants in Poland had significantly shorter LTL than in the other study centers, whereas participants in the Netherlands had significantly longer LTL than most of the other centers (p < 0.01). An analysis of LTL as a continuous outcome against physical functioning by using linear models revealed inconsistent findings. In contrast, based on an analysis of contrasting telomere lengths (first vs. fifth quintile of LTL), a significant odds ratio (OR) of 1.7 (95% CI: 1.1 -2.6; p < 0.05) of having functional limitation was observed in those belonging to the first LTL quintile compared to the fifth. Interestingly, having the shortest LTL was still related to a higher likelihood of having physical limitation when compared to all remaining quintiles (OR: 1.5, 95% CI: 1.1 -2.1; p < 0.05), even after adjustment by study center, age, sex, and overweight status. Collectively, our findings suggest that short LTL is an independent risk factor that accounts for functional decline in elderly European populations. The influence of LTL on functional limitation seems driven by the detrimental effect of having short telomeres rather than reflecting a linear dose-response relationship.
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| 2. |
- Montiel Rojas, Diego, 1984-
(författare)
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Diet and sarcopenia risk in community-dwelling older European adults
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The age-related decline in muscle strength and muscle mass can lead to sarcopenia with higher risk of falls, disability, and loss of independence. In this context, healthy dietary habits have the potential to delay onset of physical limitations, thereby promoting healthy ageing. The overall aim of the thesis was to investigate the role of dietary habits on indicators ofmuscle health in a sample of community-dwelling older European men and women. The studies were performed within the frame of the NU-AGE project, a multi-centre study aiming to determine the impact of dietary habits on age-related functional decline. Studies I-III were based on crosssectional analyses, whereas study IV was a randomised controlled trial (RCT). In summary, Study I highlighted the independent roles of dietary protein amount and quality for muscle health in older adults. A positive linear dose-response relationship existed between protein intake and muscle health, with increased intake of plant-based proteins to the detriment of animal-based proteins was associated with reduced sarcopenia risk. Study II revealed that increased poly-unsaturated fatty acids intake to the detriment of saturated fatty acids was associated with lower sarcopenia risk in older adults with a dietary protein intake below 1.1 g/kg of body weight. In Study III, beneficial links between dietary fibre intake and muscle mass were observed in older European adults. In Study IV, a one-year RCT promoting adherence to a Mediterranean-style diet did not result in significant changes in muscle strength or mass. In conclusion, the present dissertation emphasised the important potential of macronutrient amount and quality in the prevention of age-related loss of muscle strength and muscle mass. However, future experimental studies are warranted to clarify the impact of whole-diet approaches, such as the Mediterranean diet, on the maintenance of muscle health in older adults.
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| 3. |
- Strandberg, Emelie, 1986-, et al.
(författare)
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Influence of combined resistance training and healthy diet on muscle mass in healthy elderly women : a randomized controlled trial
- 2015
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Ingår i: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 119:8, s. 918-925
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Tidskriftsartikel (refereegranskat)abstract
- The delivery of efficient nonpharmacological treatment to prevent the loss of muscle mass in older adults is a major challenge, and information on the combined effects of training and diet is particularly important. Here we aimed to evaluate the effects of 24 wk of resistance training combined with a healthy dietary approach (n-6/n-3 ratio < 2) in a population of healthy and physically active older women (65-70 years). The three-armed randomized controlled trial included a resistance training + healthy diet group (RT-HD), a resistance training group (RT), and controls (CON). All subjects included in the study were physically active and had low levels of serum inflammatory markers. In accordance with the dietary goals, the n-6/n-3 ratio dietary intake significantly decreased only in RT-HD by 42%. An increase in 1 repetition maximum in leg extension occurred in RT (+20.4%) and RT-HD (+20.8%), but not in CON. Interestingly, leg lean mass significantly increased only in RT-HD (+1.8%). While there were no changes in serum C-reactive protein and IL-6 levels, a significant decrease in serum level of the pro-inflammatory precursor arachidonic acid (-5.3 +/- 9.4%) together with an increase in serum n-3 docosahexaenoic acid (+8.3%) occurred only in RT-HD. Altogether, this study demonstrates that the effects of resistance training on muscle mass in healthy older adults can be optimized by the adoption of a healthy diet.
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| 4. |
- Bankole, Landry-Cyrille, 1970-, et al.
(författare)
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Fibre type-specific satellite cell content in two models of muscle disease
- 2013
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Ingår i: Histopathology. - : Wiley. - 0309-0167 .- 1365-2559. ; 63:6, s. 826-832
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Muscle satellite cells (SCs) are responsible for the regenerative events following muscle fibre injury. This study aimed to improve our understanding of SC behaviour in two models of muscle disorder with different pathological mechanisms and onset of disease.Methods and results: Pax7(+)SC content was assessed in types I and II fibres of patients with Duchenne muscular dystrophy (DMD; n=9; age 132years), polymyositis/dermatomyositis (PM/DM; n=9; age 52 +/- 12years) and in controls (n=5; age 26 +/- 5years). Pax7(+)SCs number in type I and II fibres was higher (P<0.05) in DMD and in PM/DM compared to controls. Type I fibres were associated with a higher number of Pax7(+)SCs compared to type II fibres only in DMD; Pax7(+)SCs number in type I fibres was about threefold higher in DMD compared to PM/DM (P<0.05). In DMD, Pax7(+)SC content in small regenerating fibres (0.09 +/- 0.09 SCs/fibre) was similar to that in fibres from healthy skeletal muscle. The proportion of activated SCs (Ki-67(+)SCs) was fivefold lower in DMD (0.4 +/- 0.4%) compared to PM/DM (2.8 +/- 2%). Pax7(+) cells located outside the basal lamina were observed in DMD muscles only.Conclusion: The capacity to generate new SCs is increased even in severely impaired muscles and a fibre type-specific enhancement of SC occurs in type I muscle fibres in DMD.
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| 5. |
- Bankole, Landry-Cyrille, 1977-, et al.
(författare)
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Safety and efficacy of a 6-month home-based exercise program in patients with facioscapulohumeral muscular dystrophy A randomized controlled trial
- 2016
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Ingår i: Medicine. - : Lippincott Williams & Wilkins. - 0025-7974 .- 1536-5964. ; 95:31
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Tidskriftsartikel (refereegranskat)abstract
- Background: Previous randomized controlled trials investigating exercise training programs in facioscapulohumeral muscular dystrophy (FSHD) patients are scarce and of short duration only. This study assessed the safety and efficacy of a 6-month home-ased exercise training program on fitness, muscle, and motor function in FSHD patients.Methods: Sixteen FSHD patients were randomly assigned to training (TG) and control (CG) groups (both n=8) in a home-based exercise intervention. Training consisted of cycling 3 times weekly for 35minutes (combination of strength, high-intensity interval, and low-intensity aerobic) at home for 24 weeks. Patients in CG also performed an identical training program (CTG) after 24 weeks. The primary outcome was change in peak oxygen uptake (VO2 peak) measured every 6 weeks. The principal secondary outcomes were maximal quadriceps strength (MVC) and local quadriceps endurance every 12 weeks. Other outcome measures included maximal aerobic power (MAP) and experienced fatigue every 6 weeks, 6-minute walking distance every 12 weeks, and muscle characteristics from vastus lateralis biopsies taken pre- and postintervention.Results: The compliance rate was 91% in TG. Significant improvements with training were observed in the VO2 peak (+19%, P= 0.002) and MAP by week 6 and further to week 24. Muscle endurance, MVC, and 6-minute walking distance increased and experienced fatigue decreased. Muscle fiber cross-sectional area and citrate synthase activity increased by 34% (P=0.008) and 46% (P=0.003), respectively. Dystrophic pathophysiologic patterns were not exacerbated. Similar improvements were experienced by TG and CTG.Conclusions: A combined strength and interval cycling exercise-training program compatible with patients' daily professional and social activities leads to significant functional benefits without compromising muscle tissue.
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| 6. |
- Daussin, Frederic, et al.
(författare)
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Effect of interval versus continuous training on cardiorespiratory and mitochondrial functions : relationship to aerobic performance improvements in sedentary subjects
- 2008
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Ingår i: American Journal of Physiology. Regulatory Integrative and Comparative Physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 295:1, s. R264-272
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Tidskriftsartikel (refereegranskat)abstract
- The goal of the study was to determine the effects of continuous (CT) vs. intermittent (IT) training yielding identical mechanical work and training duration on skeletal muscle and cardiorespiratory adaptations in sedentary subjects. Eleven subjects (6 men and 5 women, 45 +/- 3 years) were randomly assigned to either of the two 8-wk training programs in a cross-over design, separated by 12 wk of detraining. Maximal oxygen uptake (Vo2max) increased after both trainings (9% with CT vs. 15% with IT), whereas only IT was associated with faster Vo2 kinetics (tau: 68.0 +/- 1.6 vs. 54.9 +/- 0.7 s, P < 0.05) measured during a test to exhaustion (TTE) and with improvements in maximal cardiac output (Qmax, from 18.1 +/- 1.1 to 20.1 +/- 1.2 l/min; P < 0.01). Skeletal muscle mitochondrial oxidative capacities (Vmax) were only increased after IT (3.3 +/- 0.4 before and 4.5 +/- 0.6 micromol O2 x min(-1) x g dw(-1) after training; P < 0.05), whereas capillary density increased after both trainings, with a two-fold higher enhancement after CT (+21 +/- 1% for IT and +40 +/- 3% after CT, P < 0.05). The gain of Vmax was correlated with the gain of TTE and the gain of Vo2max with IT. The gain of Qmax was also correlated with the gain of VO2max. These results suggest that fluctuations of workload and oxygen uptake during training sessions, rather than exercise duration or global energy expenditure, are key factors in improving muscle oxidative capacities. In an integrative view, IT seems optimal in maximizing both peripheral muscle and central cardiorespiratory adaptations, permitting significant functional improvement. These data support the symmorphosis concept in sedentary subjects.
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| 7. |
- Daussin, Frédéric N, et al.
(författare)
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Improvement of VO2max by cardiac output and oxygen extraction adaptation during intermittent versus continuous endurance training
- 2007
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Ingår i: European Journal of Applied Physiology. - New York, USA : Springer. - 1439-6319 .- 1439-6327. ; 101:3, s. 377-83
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Tidskriftsartikel (refereegranskat)abstract
- Improvement of exercise capacity by continuous (CT) versus interval training (IT) remains debated. We tested the hypothesis that CT and IT might improve peripheral and/or central adaptations, respectively, by randomly assigning 10 healthy subjects to two periods of 24 trainings sessions over 8 weeks in a cross-over design, separated by 12 weeks of detraining. Maximal oxygen uptake (VO2max), cardiac output (Qmax) and maximal arteriovenous oxygen difference (Da-vO2max) were obtained during an exhaustive incremental test before and after each training period. VO2max and Qmax increased only after IT (from 26.3 +/- 1.6 to 35.2 +/- 3.8 ml min(-1) kg(-1) and from 17.5 +/- 1.3 to 19.5 +/- 1.8 l min(-1), respectively; P < 0.01). Da-vO2max increased after both protocols (from 11.0 +/- 0.8 to 12.7 +/- 1.0; P < 0.01 and from 11.0 +/- 0.8 to 12.1 +/- 1.0 ml 100 ml(-1), P < 0.05 in CT and IT, respectively). At submaximal intensity a significant rightward shift of the Q/Da-vO2 relationship appeared only after CT. These results suggest that in isoenergetic training, central and peripheral adaptations in oxygen transport and utilization are training-modality dependant. IT improves both central and peripheral components of Da-vO2max whereas CT is mainly associated with greater oxygen extraction.
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| 8. |
- Daussin, Frederic, et al.
(författare)
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Training at high exercise intensity promotes qualitative adaptations of mitochondrial function in human skeletal muscle
- 2008
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Ingår i: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 104:5, s. 1436-1441
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Tidskriftsartikel (refereegranskat)abstract
- This study explored mitochondrial capacities to oxidize carbohydrate and fatty acids and functional optimization of mitochondrial respiratory chain complexes in athletes who regularly train at high exercise intensity (ATH, n = 7) compared with sedentary (SED, n = 7). Peak O(2) uptake (Vo(2max)) was measured, and muscle biopsies of vastus lateralis were collected. Maximal O(2) uptake of saponin-skinned myofibers was evaluated with several metabolic substrates [glutamate-malate (V(GM)), pyruvate (V(Pyr)), palmitoyl carnitine (V(PC))], and the activity of the mitochondrial respiratory complexes II and IV were assessed using succinate (V(s)) and N,N,N',N'-tetramethyl-p-phenylenediamine dihydrochloride (V(TMPD)), respectively. Vo(2max) was higher in ATH than in SED (57.8 +/- 2.2 vs. 31.4 +/- 1.3 ml.min(-1).kg(-1), P < 0.001). V(GM) was higher in ATH than in SED (8.6 +/- 0.5 vs. 3.3 +/- 0.3 micromol O(2).min(-1).g dry wt(-1), P < 0.001). V(Pyr) was higher in ATH than in SED (8.7 +/- 1.0 vs. 5.5 +/- 0.2 micromol O(2).min(-1).g dry wt(-1), P < 0.05), whereas V(PC) was not significantly different (5.3 +/- 0.9 vs. 4.4 +/- 0.5 micromol O(2).min(-1).g dry wt(-1)). V(S) was higher in ATH than in SED (11.0 +/- 0.6 vs. 6.0 +/- 0.3 micromol O(2).min(-1).g dry wt(-1), P < 0.001), as well as V(TMPD) (20.1 +/- 1.0 vs. 16.2 +/- 3.4 micromol O(2).min(-1).g dry wt(-1), P < 0.05). The ratios V(S)/V(GM) (1.3 +/- 0.1 vs. 2.0 +/- 0.1, P < 0.001) and V(TMPD)/V(GM) (2.4 +/- 1.0 vs. 5.2 +/- 1.8, P < 0.01) were lower in ATH than in SED. In conclusion, comparison of ATH vs. SED subjects suggests that regular endurance training at high intensity promotes the enhancement of maximal mitochondrial capacities to oxidize carbohydrate rather than fatty acid and induce specific adaptations of the mitochondrial respiratory chain at the level of complex I.
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| 9. |
- Di Donna, S, et al.
(författare)
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Regenerative capacity of human satellite cells : the mitotic clock in cell transplantation
- 2000
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Ingår i: Neurological Sciences. - New York, USA : Springer-Verlag New York. - 1590-1874 .- 1590-3478. ; 21:5 Suppl, s. S943-51
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Tidskriftsartikel (refereegranskat)abstract
- In this communication, we will review the problems caused by cell-mediated gene therapy, taking skeletal muscle as a physiological model. In particular we have utilised vectors transferring telomerase under the control of retroviral promoters into human satellite cells. The set of results presented here has several implications regarding gene therapy trials. Nevertheless, more experiments will be required to fully validate this cellular model and to use telomerase to safely extend the lifespan of putative gene therapy vectors.
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| 10. |
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| 11. |
- Dufour, Stéphane P, et al.
(författare)
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Exercise training in normobaric hypoxia in endurance runners. I. Improvement in aerobic performance capacity.
- 2006
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Ingår i: Journal of applied physiology. - Betsheda, USA : American Physiological Society. - 8750-7587 .- 1522-1601. ; 100:4, s. 1238-48
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates whether a 6-wk intermittent hypoxia training (IHT), designed to avoid reductions in training loads and intensities, improves the endurance performance capacity of competitive distance runners. Eighteen athletes were randomly assigned to train in normoxia [Nor group; n = 9; maximal oxygen uptake (VO2 max) = 61.5 +/- 1.1 ml x kg(-1) x min(-1)] or intermittently in hypoxia (Hyp group; n = 9; VO2 max = 64.2 +/- 1.2 ml x kg(-1) x min(-1)). Into their usual normoxic training schedule, athletes included two weekly high-intensity (second ventilatory threshold) and moderate-duration (24-40 min) training sessions, performed either in normoxia [inspired O2 fraction (FiO2) = 20.9%] or in normobaric hypoxia (FiO2) = 14.5%). Before and after training, all athletes realized 1) a normoxic and hypoxic incremental test to determine VO2 max and ventilatory thresholds (first and second ventilatory threshold), and 2) an all-out test at the pretraining minimal velocity eliciting VO2 max to determine their time to exhaustion (T(lim)) and the parameters of O2 uptake (VO2) kinetics. Only the Hyp group significantly improved VO2 max (+5% at both FiO2, P < 0.05), without changes in blood O2-carrying capacity. Moreover, T(lim) lengthened in the Hyp group only (+35%, P < 0.001), without significant modifications of VO2 kinetics. Despite similar training load, the Nor group displayed no such improvements, with unchanged VO2 max (+1%, nonsignificant), T(lim) (+10%, nonsignificant), and VO2 kinetics. In addition, T(lim) improvements in the Hyp group were not correlated with concomitant modifications of other parameters, including VO2 max or VO2 kinetics. The present IHT model, involving specific high-intensity and moderate-duration hypoxic sessions, may potentialize the metabolic stimuli of training in already trained athletes and elicit peripheral muscle adaptations, resulting in increased endurance performance capacity.
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| 12. |
- Echaniz-Laguna, Andoni, et al.
(författare)
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Muscular mitochondrial function in amyotrophic lateral sclerosis is progressively altered as the disease develops : A temporal study in man
- 2006
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Ingår i: Experimental Neurology. - San Diego, USA : Elsevier. - 0014-4886 .- 1090-2430. ; 198:1, s. 25-30
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Tidskriftsartikel (refereegranskat)abstract
- We performed repeated analysis of mitochondrial respiratory function in skeletal muscle (SM) of patients with early-stage sporadic amyotrophic lateral sclerosis (SALS) to determine whether mitochondrial function was altered as the disease advanced. SM biopsies were obtained from 7 patients with newly diagnosed SALS, the same 7 patients 3 months later, and 7 sedentary controls. Muscle fibers were permeabilized with saponin, then skinned and placed in an oxygraphic chamber to measure basal and maximal adenosine diphosphate (ADP)-stimulated respiration rates and to assess mitochondrial regulation by ADP. We found that the maximal oxidative phosphorylation capacity of muscular mitochondria significantly increased, and muscular mitochondrial respiratory complex IV activity significantly decreased as the disease advanced. This temporal study demonstrates for the first time that mitochondrial function in SM in human SALS is progressively altered as the disease develops.
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| 13. |
- Kadi, Fawzi, 1970-, et al.
(författare)
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The biology of satellite cells and telomeres in human skeletal muscle : effects of aging and physical activity
- 2010
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : Wiley. - 0905-7188 .- 1600-0838. ; 20:1, s. 39-48
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Forskningsöversikt (refereegranskat)abstract
- The decline in the neuromuscular function affects the physical performance and is a threat for independent living in later life. The age-related decrease in muscle satellite cells observed by the age of 70 can be specific to type II fibers in some muscles. Several studies have shown that different forms of exercise induce the expansion of satellite cell pool in human skeletal muscle of young and elderly. Exercise is a powerful non-pharmacological tool inducing the renewal of the satellite cell pool in skeletal muscles. Skeletal muscle is not a stable tissue as satellite cells are constantly recruited during normal daily activities. Satellite cells and the length of telomeres are important in the context of muscle regeneration. It is likely that the regulation of telomeres in vitro cannot fully mimic the behavior of telomeres in human tissues. New insights suggest that telomeres in skeletal muscle are dynamic structures under the influence of their environment. When satellite cells are heavily recruited for regenerative events as in the skeletal muscle of athletes, telomere length has been found to be either dramatically shortened or maintained and even longer than in non-trained individuals. This suggests the existence of mechanisms allowing the control of telomere length in vivo.
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| 14. |
- Kadi, Fawzi, et al.
(författare)
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The effects of regular strength training on telomere length in human skeletal muscle
- 2008
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Ingår i: Medicine & Science in Sports & Exercise. - : Lippincott Williams & Wilkins. - 0195-9131 .- 1530-0315. ; 40:1, s. 82-87
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The length of DNA telomeres is an important parameter of the proliferative potential of tissues. A recent study has reported abnormally short telomeres in skeletal muscle of athletes with exercise-associated fatigue. This important report raises the question of whether long-term practice of sports might have deleterious effects on muscle telomeres. Therefore, we aimed to compare telomere length of a group of power lifters (PL; N = 7) who trained for 8 +/- 3 yr against that of a group of healthy, active subjects (C; N = 7) with no history of strength training. METHODS: Muscle biopsies were taken from the vastus lateralis, and the mean and minimum telomeric restriction fragments (TRF) (telomere length) were determined, using the Southern blot protocol previously used for the analysis of skeletal muscle. RESULTS: There was no abnormal shortening of telomeres in PL. On the contrary, the mean (P = 0.07) and the minimum (P = 0.09) TRF lengths in PL tended to be higher than in C. In PL, the minimum TRF length was inversely correlated to the individual records in squat (r = -0.86; P = 0.01) and deadlift (r = -0.88; P = 0.01). CONCLUSION: These results show for the first time that long-term training is not associated with an abnormal shortening of skeletal muscle telomere length. Although the minimum telomere length in PL remains within normal physiological ranges, a heavier load put on the muscles means a shorter minimum TRF length in skeletal muscle.
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| 15. |
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| 16. |
- Mackey, Abigail L., et al.
(författare)
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Activation of satellite cells and the regeneration of human skeletal muscle are expedited by ingestion of nonsteroidal anti-inflammatory medication
- 2016
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Ingår i: The FASEB Journal. - Bethesda, USA : Federation of American Societies for Experimental Biology. - 0892-6638 .- 1530-6860. ; 30:6, s. 2266-2281
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Tidskriftsartikel (refereegranskat)abstract
- With this study we investigated the role of nonsteroidal anti-inflammatory drugs (NSAIDs) in human skeletal muscle regeneration. Young men ingested NSAID [1200 mg/d ibuprofen (IBU)] or placebo (PLA) daily for 2 wk before and 4 wk after an electrical stimulation-induced injury to the leg extensor muscles of one leg. Muscle biopsies were collected from the vastus lateralis muscles before and after stimulation (2.5 h and 2, 7, and 30 d) and were assessed for satellite cells and regeneration by immunohistochemistry and real-time RT-PCR, and we also measured telomere length. After injury, and compared with PLA, IBU was found to augment the proportion of ActiveNotch1(+) satellite cells at 2 d [IBU, 29 ± 3% vs. PLA, 19 ± 2% (means ± sem)], satellite cell content at 7 d [IBU, 0.16 ± 0.01 vs. PLA, 0.12 ± 0.01 (Pax7(+) cells/fiber)], and to expedite muscle repair at 30 d. The PLA group displayed a greater proportion of embryonic myosin(+) fibers and a residual ∼2-fold increase in mRNA levels of matrix proteins (all P < 0.05). Endomysial collagen was also elevated with PLA at 30 d. Minimum telomere length shortening was not observed. In conclusion, ingestion of NSAID has a potentiating effect on Notch activation of satellite cells and muscle remodeling during large-scale regeneration of injured human skeletal muscle.-Mackey, A. L., Rasmussen, L. K., Kadi, F., Schjerling, P., Helmark, I. C., Ponsot, E., Aagaard, P., Durigan, J. L. Q., Kjaer, M. Activation of satellite cells and the regeneration of human skeletal muscle are expedited by ingestion of nonsteroidal anti-inflammatory medication.
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| 17. |
- Marklund, Peter, et al.
(författare)
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Extensive inflammatory cell infiltration in human skeletal muscle in response to an ultra-endurance exercise bout in experienced athletes.
- 2013
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Ingår i: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 114:1, s. 66-72
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Tidskriftsartikel (refereegranskat)abstract
- The impact of a 24h ultra-endurance exercise bout on systemic and local muscle inflammatory reactions was investigated in nine experienced athletes. Blood and muscle biopsies were collected before (PRE), immediately after the exercise (POST) and after 28h of recovery (POST28). Circulating blood levels of leukocytes, CK, CRP and selected inflammatory cytokines were assessed together with the evaluation of the occurrence of inflammatory cells (CD3(+), CD8(+), CD68(+)) and the expression of major histocompatibility complex class-I (MHC class-I) in skeletal muscle. An extensive inflammatory cell infiltration occurred in all athletes and the number of CD3(+), CD8(+) and CD 68(+) cells were 2-3 fold higher at POST28 compared to PRE (P<0.05). The inflammatory cell infiltration was associated with a significant increase in the expression of MHC class-I in muscle fibers. There was a significant increase in blood leukocyte count, IL-6, IL-8, CRP and CK at POST. At POST28 total leukocytes, IL-6 and CK had declined, whereas IL-8 and CRP continued to increase. Increases in IL-1β and TNF-α were not significant. There were no significant associations between the magnitude of the systemic and local muscle inflammatory reactions. Signs of muscle degenerative and regenerative events were observed in all athletes with various degrees of severity and were not affected by the ultra-endurance exercise bout. In conclusion, a low-intensity but very prolonged single endurance exercise bout can generate a strong inflammatory cell infiltration in skeletal muscle of well-trained experienced ultra-endurance athletes, and the amplitude of the local reaction is not proportional to the systemic inflammatory response.
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| 18. |
- N'Guessan, Benoit, et al.
(författare)
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Evaluation of quantitative and qualitative aspects of mitochondrial function in human skeletal and cardiac muscles
- 2004
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Ingår i: Molecular and Cellular Biochemistry. - Dordrecht, Netherlands : Kluwer Academic Publishers. - 0300-8177 .- 1573-4919. ; 256-257:1-2, s. 267-80
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Forskningsöversikt (refereegranskat)abstract
- Techniques and protocols of assessment of mitochondrial properties are of physiological and physiopathological important significance. A precise knowledge of the advantages and limitations of the different protocols used to investigate the mitochondrial function, is therefore necessary. This report presents examples of how the skinned (or permeabilized) fibers technique could be applied for the polarographic determination of the actual quantitative and qualitative aspects of mitochondrial function in human muscle samples. We described and compared the main available respiration protocols in order to sort out which protocol seems more appropriate for the characterization of mitochondrial properties according to the questions under consideration: quantitative determination of oxidative capacities of a given muscle, characterization of the pattern of control of mitochondrial respiration, or assessment of a mitochondrial defect at the level of the respiratory chain complexes. We showed that while protocol A, using only two levels of the phosphate acceptor adenosine diphosphate (ADP) concentration and the adjunction of creatine, could be used for the determination of quantitative changes in very small amount of muscle samples, the ADP sensitivity of mitochondrial respiration was underestimated by this protocol in muscles with high oxidative capacities. The actual apparent Km for ADP and the role of functional activation of miCK in ATP production and energy transfer in oxidative muscles, are well-assessed by protocol B (in the absence of creatine) together with protocol C (in the presence of creatine) that use increasing concentrations of ADP ranging from 2.5-2000 microM. Protocol D is well-adapted to investigate the potential changes at different levels of the respiratory chain, by the use of specific substrates and inhibitors. As can be seen from the present data and the current review of previous reports in the literature, a standardization of the respiration protocols is needed for useful comparisons between studies.
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| 19. |
- Pialoux, V., et al.
(författare)
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Effects of exercise and training in hypoxia on antioxidant/pro-oxidant balance
- 2006
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Ingår i: European Journal of Clinical Nutrition. - London, United Kingdom : Nature Publishing Group. - 0954-3007 .- 1476-5640. ; 60:12, s. 1345-54
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The aim was to investigate the effects of acute exercise under hypoxic condition and the repetition of such exercise in a 'living low-training high' training on the antioxidant/prooxidant balance.Design: Randomized, repeated measures design.Setting: Faculté de Médecine, Clermont-Ferrand, France.Subjects: Fourteen runners were randomly divided into two groups. A 6-week endurance training protocol integrated two running sessions per week at the second ventilatory threshold into the usual training.Intervention: A 6-week endurance training protocol integrated two running sessions per week at the second ventilatory threshold into the usual training. The first hypoxic group (HG, n=8) carried out these sessions under hypoxia (3000 m simulated altitude) and the second normoxic group (NG, n=6) in normoxia. In control period, the runners were submitted to two incremental cycling tests performed in normoxia and under hypoxia (simulated altitude of 3000 m). Plasma levels of advanced oxidation protein products (AOPP), malondialdehydes (MDA) and lipid oxidizability, ferric-reducing antioxidant power (FRAP), lipid-soluble antioxidants (alpha-tocopherol and beta-carotene) normalized for triacyglycerols and cholesterol were measured before and after the two incremental tests and at rest before and after training.Results: No significant changes of MDA and AOPP level were observed after normoxic exercise, whereas hypoxic exercise induced a 56% rise of MDA and a 44% rise of AOPP. Plasma level of MDA and arterial oxygen hemoglobin desaturations after the acute both exercises were highly correlated (r=0.73). alpha-Tocopherol normalized for cholesterol and triacyglycerols increased only after hypoxic exercise (10-12%, P<0.01). After training, FRAP resting values (-21%, P<0.05) and alpha-tocopherol/triacyglycerols ratio (-24%, P<0.05) were diminished for HG, whereas NG values remained unchanged.Conclusions: Intense exercise and hypoxia exposure may have a cumulative effect on oxidative stress. As a consequence, the repetition of such exercise characterizing the 'living low-training high' model has weakened the antioxidant capacities of the athletes.Sponsorship: International Olympic Committee and the Direction Régionale de la Jeunesse et des Sports de la Région Auvergne.
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| 20. |
- Ponsot, Elodie, 1973-, et al.
(författare)
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Exercise training in normobaric hypoxia in endurance runners. II. Improvement of mitochondrial properties in skeletal muscle
- 2006
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Ingår i: Journal of applied physiology. - Betsheda, USA : American Physiological Society. - 8750-7587 .- 1522-1601. ; 100:4, s. 1249-57
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates whether adaptations of mitochondrial function accompany the improvement of endurance performance capacity observed in well-trained athletes after an intermittent hypoxic training program. Fifteen endurance-trained athletes performed two weekly training sessions on treadmill at the velocity associated with the second ventilatory threshold (VT2) with inspired O2 fraction = 14.5% [hypoxic group (Hyp), n = 8] or with inspired O2 fraction = 21% [normoxic group (Nor), n = 7], integrated into their usual training, for 6 wk. Before and after training, oxygen uptake (VO2) and speed at VT2, maximal VO2 (VO2 max), and time to exhaustion at velocity of VO2 max (minimal speed associated with VO2 max) were measured, and muscle biopsies of vastus lateralis were harvested. Muscle oxidative capacities and sensitivity of mitochondrial respiration to ADP (Km) were evaluated on permeabilized muscle fibers. Time to exhaustion, VO2 at VT2, and VO2 max were significantly improved in Hyp (+42, +8, and +5%, respectively) but not in Nor. No increase in muscle oxidative capacity was obtained with either training protocol. However, mitochondrial regulation shifted to a more oxidative profile in Hyp only as shown by the increased Km for ADP (Nor: before 476 +/- 63, after 524 +/- 62 microM, not significant; Hyp: before 441 +/- 59, after 694 +/- 51 microM, P < 0.05). Thus including hypoxia sessions into the usual training of athletes qualitatively ameliorates mitochondrial function by increasing the respiratory control by creatine, providing a tighter integration between ATP demand and supply.
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| 21. |
- Ponsot, Elodie, 1973-, et al.
(författare)
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Impairment of maximal aerobic power with moderate hypoxia in endurance athletes : do skeletal muscle mitochondria play a role?
- 2010
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Ingår i: American Journal of Physiology. Regulatory Integrative and Comparative Physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 298:3, s. R558-R566
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the role of central vs. peripheral factors in the limitation of maximal oxygen uptake ((V) over dot O-2max) with moderate hypoxia [inspired fraction (FIO2) = 14.5%]. Fifteen endurance-trained athletes performed maximal cycle incremental tests to assess (V) over dotO(2max), maximal cardiac output ((Q) over dot(max)), and maximal arteriovenous oxygen (a-vO(2)) difference in normoxia and hypoxia. Muscle biopsies of vastus lateralis were taken 1 wk before the cycling tests to evaluate maximal muscle oxidative capacity ((V) over dot(max)) and sensitivity of mitochondrial respiration to ADP (K-m) on permeabilized muscle fibers in situ. Those athletes exhibiting the largest reduction of (V) over dotO(2max) in moderate hypoxia (Severe Loss group: -18 +/- 2%) suffered from significant reductions in Q(max) (-4 +/- 1%) and maximal a-vO(2) difference (-14 +/- 2%). Athletes who well tolerated hypoxia, as attested by a significantly smaller drop of (V) over dotO(2max) with hypoxia (Moderate Loss group: -7 +/- 1%), also display a blunted (Q) over dot(max) (-9 +/- 2%) but, conversely, were able to maintain maximal a-vO(2) difference (+1 +/- 2%). Though (V) over dot(max) was similar in the two experimental groups, the smallest reduction of (V) over dotO(2max) with moderate hypoxia was observed in those athletes presenting the lowest apparent Km for ADP in the presence of creatine (K-m (+) (Cr)). In already-trained athletes with high muscular oxidative capacities, the qualitative, rather than quantitative, aspects of the mitochondrial function may constitute a limiting factor to aerobic ATP turnover when exercising at low FIO2, presumably through the functional coupling between the mitochondrial creatine kinase and ATP production. This study suggests a potential role for peripheral factors, including the alteration of cellular homeostasis in active muscles, in determining the tolerance to hypoxia in maximally exercising endurance-trained athletes.
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| 22. |
- Ponsot, Elodie, 1973-, et al.
(författare)
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Mitochondrial tissue specificity of substrates utilization in rat cardiac and skeletal muscles
- 2005
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Ingår i: Journal of Cellular Physiology. - Hoboken, USA : John Wiley & Sons. - 0021-9541 .- 1097-4652. ; 203:3, s. 479-86
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Tidskriftsartikel (refereegranskat)abstract
- As energetic metabolism is crucial for muscles, they develop different adaptations to respond to fluctuating demand among muscle types. Whereas quantitative characteristics are known, no study described simultaneously quantitative and qualitative differences among muscle types in terms of substrates utilization patterns. This study thus defined the pattern of substrates preferential utilization by mitochondria from glycolytic gastrocnemius (GAS) and oxidative soleus (SOL) skeletal muscles and from heart left ventrical (LV) in rats. We measured in situ, ADP (2 mM)-stimulated, mitochondrial respiration rates from skinned fibers in presence of increasing concentrations of pyruvate (Pyr) + malate (Mal), palmitoyl-carnitine (Palm-C) + Mal, glutamate (Glut) + Mal, glycerol-3-phosphate (G3-P), lactate (Lact) + Mal. Because the fibers oxygen uptake (Vs) followed Michaelis-Menten kinetics in function of substrates level we determined the Vs and Km, representing maximal oxidative capacity and the mitochondrial sensibility for each substrate, respectively. Vs were in the order GAS < SOL < LV for Pyr, Glu, and Palm-C substrates, whereas in the order SOL = LV < GAS with G3-P. Moreover, the relative capacity to oxidize Palm-C is extremely higher in LV than in SOL. Vs was not stimulated by the Lact substrate. The Km was equal for Pyr among muscles, but much lower for G3-P in GAS and lower for Palm-C in LV. These results demonstrate qualitative mitochondrial tissue specificity for metabolic pathways. Mitochondria of glycolytic muscle fibers are well adapted to play a central role for maintaining a satisfactory cytosolic redox state in these fibers, whereas mitochondria of LV developed important capacities to use fatty acids.
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| 23. |
- Ponsot, Elodie, 1973-, et al.
(författare)
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Signal modelization for improved precision of assessment of minimum and mean telomere lengths
- 2008
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Ingår i: Electrophoresis. - : Wiley-VCH Verlagsgesellschaft. - 0173-0835 .- 1522-2683. ; 29:2, s. 542-544
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Tidskriftsartikel (refereegranskat)abstract
- Telomere length is an important measure of cell and tissue regenerative capacities. The mean telomere length is classically used as global indicator of a tissue telomere length. In skeletal muscle, which is made of postmitotic myonuclei and satellite cells (muscle stem cells), minimum telomere length is also used to assess the telomere length of satellite cells and newly incorporated myonuclei. At present, the estimation of the method reproducibility during the assessment of mean and minimum telomere length using Southern blot analysis has never been documented. The aim of this report is to describe a signal modelization for improved precision of assessment of minimum and mean telomere lengths and to document the method reproducibility. Telomeres are assessed using a Southern technique where the gel is directly hybridized with the specific probe without the membrane-transferring step in order to prevent telomeric low signal loss. We found that the improved signal analysis for determination of telomere length is associated with coefficients of variation ranging from 1.37 to 4.29% for the mean telomeric restriction fragment (TRF) length and from 2.04 to 4.95% for the minimum TRF length. Improved method reproducibility would allow saving time and biological material as duplicate and triplicate measurement of the same sample is no longer required.
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| 24. |
- Ponsot, Elodie, 1973-, et al.
(författare)
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Skeletal muscle telomere length is not impaired in healthy physically active old women and men
- 2008
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Ingår i: Muscle and Nerve. - : Wiley. - 0148-639X .- 1097-4598. ; 37:4, s. 467-472
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Tidskriftsartikel (refereegranskat)abstract
- We have previously shown that the number of satellite cells is lower in old than young men and women. The aim of this study was to further explore the effects of aging on the regenerative potential of skeletal muscle in 16 young and 26 old men and women with comparable physical activity level (young, 25 +/- 4 years; old, 75 +/- 4 years). Mean and minimum telomere lengths were determined using Southern blot analyses on biopsies obtained from the tibialis anterior muscle. There were no significant age or gender effects on mean and minimal telomeric lengths, suggesting that the replicative potential in the remaining satellite cells in the tibialis anterior muscle is not impaired with increasing age and the existence of in vivo regulatory mechanisms allowing the maintenance of telomere length. These results imply that moderate physical activity regularly performed by old subjects is not associated with accelerated telomere loss.
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| 25. |
- Ponsot, Elodie, 1973-, et al.
(författare)
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Telomere length and regulatory proteins in human skeletal muscle with and without ongoing regenerative cycles
- 2012
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Ingår i: Experimental Physiology. - Hoboken, USA : Wiley-Blackwell. - 0958-0670 .- 1469-445X. ; 97:6, s. 774-784
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Tidskriftsartikel (refereegranskat)abstract
- New insights suggest the existence of telomere regulatory mechanisms in several adult tissues. In this study, we aimed to assess in vivo telomere length and the presence of specific proteins involved in telomere regulation in a model of human skeletal muscle with (patients with dermatomyosis or polymyositis) and without ongoing regenerative events (healthy subjects). Mean (meanTRF) and minimal telomere (miniTRF) lengths and the expression of telomerase, tankyrase 1, TRF2 (telomeric repeat binding factor 2) and POT1 (protection of telomeres 1) were investigated in skeletal muscle samples from 12 patients (MYO) and 13 healthy subjects (CON). There was no significant shortening of telomeres in skeletal muscle from patients compared with control subjects (MYO, meanTRF length 11.0 ± 1.8 kbp and miniTRF length 4.7 ± 0.8 kbp; CON, meanTRF length 10.4 ± 1.1 kbp and miniTRF length 4.6 ± 0.5 kbp). Theoretically, telomere length can be controlled by endogenous mechanisms. Here, we show for the first time that expression levels of telomerase, tankyrase 1, TRF2 and POT1 were, respectively, six-, seven-, three- and fivefold higher in the nuclear fraction of skeletal muscle of MYO compared with CON (P < 0.05). This suggests the existence of endogenous mechanisms allowing for telomere regulation in skeletal muscle with ongoing cycles of degeneration and regeneration and a model where regulatory factors are possibly involved in the protection of skeletal muscle telomeres.
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| 26. |
- Ponsot, Elodie, 1973-, et al.
(författare)
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Telomere length of anterior crucial ligament after rupture : similar telomere length in injured and noninjured ACL portions
- 2011
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Ingår i: Journal of Orthopaedic Research. - : John Wiley & Sons. - 0736-0266 .- 1554-527X. ; 29:1, s. 79-83
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Tidskriftsartikel (refereegranskat)abstract
- The regeneration of ligaments following injury is a slow process compared to the healing of many other tissues and the underlying mechanisms remain unknown. The purpose of the study was to evaluate the proliferative potential of ligaments by assessing telomere length within three distinct parts of human anterior cruciate ligament (ACL) obtained during ACL reconstruction: the macroscopically injured proximal part and macroscopically noninjured mid- and distal portions in eight subjects (age 28 +/- 8 years). The mean telomere length in ACL was within normal range of values usually reported for other tissues indicating that the endogenous machinery responsible for the proliferative potential of ligament is not implicated in its poor healing capacity. The three ACL parts showed similar mean TRF lengths (distal part: 11.5 +/- 0.8 kbp, mid-portion: 11.8 +/- 1.2 kbp, proximal part: 11.9 +/- 1.6 kbp) and there was no relationship between mean telomere length in ACL and the healing duration after rupture. This implies that despite the occurrence of ligament repair including a phase of intense cell proliferation the proliferative potential of ruptured ACL is not impaired. This knowledge is important for scientists and clinicians aiming to understand the mechanisms behind the low healing capacity of ligament.
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| 27. |
- Sillanpää, Elina, et al.
(författare)
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Leukocyte and Skeletal Muscle Telomere Length and Body Composition in Monozygotic Twin Pairs Discordant for Long-term Hormone Replacement Therapy
- 2017
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Ingår i: Twin Research and Human Genetics. - Cambridge, United Kingdom : Cambridge University Press. - 1832-4274 .- 1839-2628. ; 20:2, s. 119-131
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Tidskriftsartikel (refereegranskat)abstract
- Estrogen-based hormone replacement therapy (HRT) may be associated with deceleration of cellular aging. We investigated whether long-term HRT has effects on leukocyte (LTL) or mean and minimum skeletal muscle telomere length (SMTL) in a design that controls for genotype and childhood environment. Associations between telomeres, body composition, and physical performance were also examined. Eleven monozygotic twin pairs (age 57.6 ± 1.8 years) discordant for HRT were studied. Mean duration of HRT use was 7.3 ± 3.7 years in the user sister, while their co-twins had never used HRT. LTL was measured by qPCR and SMTLs by southern blot. Body and muscle composition were estimated by bioimpedance and computed tomography, respectively. Physical performance was measured by jumping height and grip strength. HRT users and non-users did not differ in LTL or mean or minimum SMTL. Within-pair correlations were high in LTL (r = 0.69, p = .020) and in mean (r = 0.74, p = .014) and minimum SMTL (r = 0.88, p = .001). Body composition and performance were better in users than non-users. In analyses of individuals, LTL was associated with BMI (r 2 = 0.30, p = .030), percentage total body (r 2 = 0.43, p = .014), and thigh (r 2 = 0.55, p = .004) fat, while minimum SMTL was associated with fat-free mass (r 2 = 0.27, p = .020) and thigh muscle area (r 2 = 0.42, p = .016). We found no associations between HRT use and telomere length. Longer LTLs were associated with lower total and regional fat, while longer minimum SMTLs were associated with higher fat-free mass and greater thigh muscle area. This suggests that telomeres measured from different tissues may have different associations with measures of body composition.
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| 28. |
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| 29. |
- Strandberg, Emelie, et al.
(författare)
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Resistance Training Alone or Combined With N-3 PUFA-Rich Diet in Older Women : Effects on Muscle Fiber Hypertrophy
- 2019
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Ingår i: The journals of gerontology. Series A, Biological sciences and medical sciences. - : Oxford University Press. - 1079-5006 .- 1758-535X. ; 74:4, s. 489-494
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Tidskriftsartikel (refereegranskat)abstract
- We aimed to examine cellular and molecular changes in skeletal muscle of recreationally active older women in response to 24 weeks of combined resistance training and N-3 PUFA-rich healthy diet. Sixty-three women (65-70 years) were randomized into resistance training and healthy diet rich in N-3PUFAs (RT-HD), resistance training only (RT) and controls (CON). Fiber type-specific morphological characteristics and gene expression of inflammatory biomarkers and regulators of muscle mass were analyzed in m. vastus lateralis biopsies obtained before the intervention and 4 days after the last training session. Gene expression of the proinflammatory cytokine IL-1β was downregulated (p < .05) and that of the regulator of cellular growth mTOR (p < 0.05) was upregulated in skeletal muscle of RT-HD only. There was also a significant hypertrophy of fast type IIA muscle fibers in RT-HD only (+23%, p < .05). In conclusion, resistance training combined to an N-3 PUFA-rich healthy diet but not alone triggers local anti-inflammatory and growth responses, favoring skeletal muscle hypertrophy in already recreationally active older women.
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| 30. |
- Strandberg, Emelie, 1986-
(författare)
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Skeletal Muscle Mass & Function in Older Women : Health-Enhancing Influences of Combined Resistance Exercise & Diet
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ageing is accompanied by a progressive decline in skeletal muscle mass and strength which may lead to impaired ability to perform activities of daily living in older adults. Although the exact cause of the gradual decline in muscle mass is unknown, identifying efficient strategies aiming to prevent age-related loss of muscle mass and strength is important in order to promote healthy ageing. The overall aim of this thesis was to explore the effects of resistance training alone or combined with a healthy diet on skeletal muscle mass and function of healthy recreationally active older women and to determine mechanisms by which elevated systemic inflammation may contribute to the age-related decline of muscle mass in older adults. The combination of resistance training and a healthy diet induced gains in leg lean mass as well as greater gains in dynamic explosive force than resistance training alone in healthy recreationally active older women. The observed gains in leg lean mass were accompanied by increases in the size of type IIA muscle fibres together with down-regulation in gene expression of a pro-inflammatory factor (IL-1β) and upregulation in gene expression of a regulator of cellular growth (mTOR) in skeletal muscle of older women. Additionally, reduced muscle protein synthesis and size of muscle cells may mediate the detrimental effects of elevated circulating markers of inflammation on muscle mass in older adults. In conclusion, the present thesis depicts mechanistic links between elevated systemic marker of inflammation and muscle mass and provides new information on the effects of combined resistance training and healthy diet on muscle mass and strength in a group of healthy recreationally active older women. This knowledge is instrumental for development of strategies aiming to prevent age-related loss of muscle mass and function.
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| 31. |
- Särnblad, Stefan, 1963-, et al.
(författare)
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Acute effects of aerobic continuous, intermittent and resistance exercise on glycemia in adolescents males with type 1 diabetes
- 2021
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Ingår i: Pediatric Diabetes. - : Wiley-Blackwell Publishing Inc.. - 1399-543X .- 1399-5448. ; 22:4, s. 610-617
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Increased levels of physical activity is often associated with reduced HbA1c in individuals with diabetes. However, the effect on glycemic control differs between different programs of exercise. The aim of this study was to compare the acute effects on glycemia of resistance and two aerobic continuous and intermittent exercise bouts in adolescent males with type 1 diabetes.METHODS: Eight active males with type 1 diabetes (17.5±0.8 years, BMI: 20.8±2.2 kg/m2 , HbA1c: 7.2±0.5 % (54.9±5.3 mmol/mol)) performed four experimental sessions - non-exercise (control), resistance exercise (RE) and two isocaloric continuous (CE) and intermittent (IE) cycling exercise trials - in a randomized order. Each session consisted of 45 minutes of exercise (except for the control modality) and 60 minutes of passive recovery. Venous blood was drawn for assessment of plasma glucose (PG). A two-way repeated-measures ANOVA was used for statistical comparisons.RESULTS: A significant time-to-exercise interaction effect on PG was detected. PG significantly decreased during IE (-5.1±1.6 mmol/L) and CE (-5.4 ± 1.8 mmol/L) but not during RE (-1.0 ± 1.4 mmol/L, ns). Additionally, decreases in PG after IE and CE were sustained throughout the recovery period.CONCLUSIONS: While intermittent and continuous aerobic exercises are associated with a lowering of glycemia in male adolescents with type 1 diabetes, glycemia remained stable without significant alterations after resistance exercise. These findings hold important implications related to clinical exercise advice and disease management in adolescents with type 1 diabetes.
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| 32. |
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| 33. |
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| 34. |
- Zoll, J, et al.
(författare)
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Acute myocardial ischaemia induces specific alterations of ventricular mitochondrial function in experimental pigs
- 2005
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Ingår i: Acta Physiologica Scandinavica. - Oxon, United Kingdom : Blackwell Publishing. - 0001-6772 .- 1365-201X. ; 185:1, s. 25-32
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Tidskriftsartikel (refereegranskat)abstract
- Aims: As cardiac metabolic flexibility is crucial, this study examined whether acute ischaemia can induce specific qualitative alterations of the mitochondrial metabolic pathways as well as energy transfer systems.Methods: Left descending coronary artery ligation was performed after sternotomy in eight pigs and the heart was excised after 45 min of ischaemia. Maximal O2 uptake (V(max), micromol O2 min(-1) g(-1) dry weight) of saponin-skinned myofibres were measured from ischaemic and non-ischaemic area of ventricular myocardium.Results: V(max) decreased by approximately 20% in ischaemic myocardium with both glutamate-malate (18.1 +/- 1.3 vs. 22.1 +/- 1.7 in control, P < 0.05) and pyruvate substrates (19.3 +/- 1.0 vs. 23.3 +/- 2.0 in control, P < 0.05) whereas no difference was observed with palmitoyl carnitine (15.6 +/- 1.8 vs. 16.6 +/- 0.9 in control). The K(m) of mitochondrial respiration for ADP decreased in ischaemic heart by 24% (679 +/- 79 vs. 899 +/- 84 microm of ADP in control, P < 0.05). Moreover, the mitochondrial creatine kinase efficacy (K(m) without creatine/K(m) with creatine), representative of the coupling of oxidative phosphorylation process with the mitochondrial creatine kinase, was reduced in ischaemic heart (11.6 +/- 2.5 in ischaemic vs. 18.0 +/- 2.2 in control, P < 0.05).Conclusions: These findings argue for specific mitochondrial impairments at the level of pyruvate oxidation and creatine kinase channelling system after an acute period of in vivo ischaemia, whereas the lipid mitochondrial oxidation pathway seems to be preserved. Such a loss of metabolic flexibility following acute ischaemia could become an early feature of metabolic dysregulation of the heart.
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| 35. |
- Zoll, Joffrey, et al.
(författare)
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Exercise training in normobaric hypoxia in endurance runners. III. Muscular adjustments of selected gene transcripts
- 2006
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Ingår i: Journal of applied physiology. - Bethesda, USA : American Physiological Society. - 8750-7587 .- 1522-1601. ; 100:4, s. 1258-66
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Tidskriftsartikel (refereegranskat)abstract
- We hypothesized that specific muscular transcript level adaptations participate in the improvement of endurance performances following intermittent hypoxia training in endurance-trained subjects. Fifteen male high-level, long-distance runners integrated a modified living low-training high program comprising two weekly controlled training sessions performed at the second ventilatory threshold for 6 wk into their normal training schedule. The athletes were randomly assigned to either a normoxic (Nor) (inspired O2 fraction = 20.9%, n = 6) or a hypoxic group exercising under normobaric hypoxia (Hyp) (inspired O2 fraction = 14.5%, n = 9). Oxygen uptake and speed at second ventilatory threshold, maximal oxygen uptake (VO2 max), and time to exhaustion (Tlim) at constant load at VO2 max velocity in normoxia and muscular levels of selected mRNAs in biopsies were determined before and after training. VO2 max (+5%) and Tlim (+35%) increased specifically in the Hyp group. At the molecular level, mRNA concentrations of the hypoxia-inducible factor 1alpha (+104%), glucose transporter-4 (+32%), phosphofructokinase (+32%), peroxisome proliferator-activated receptor gamma coactivator 1alpha (+60%), citrate synthase (+28%), cytochrome oxidase 1 (+74%) and 4 (+36%), carbonic anhydrase-3 (+74%), and manganese superoxide dismutase (+44%) were significantly augmented in muscle after exercise training in Hyp only. Significant correlations were noted between muscular mRNA levels of monocarboxylate transporter-1, carbonic anhydrase-3, glucose transporter-4, and Tlim only in the group of athletes who trained in hypoxia (P < 0.05). Accordingly, the addition of short hypoxic stress to the regular endurance training protocol induces transcriptional adaptations in skeletal muscle of athletic subjects. Expressional adaptations involving redox regulation and glucose uptake are being recognized as a potential molecular pathway, resulting in improved endurance performance in hypoxia-trained subjects.
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| 36. |
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