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- Kadi, Fawzi, et al.
(författare)
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Effects of one bout of endurance exercise on the expression of myogenin in human quadriceps muscle
- 2004
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Ingår i: Histochemistry and Cell Biology. - : Springer Science and Business Media LLC. - 0948-6143 .- 1432-119X. ; 121:4, s. 329-334
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to investigate the cellular localisation of MyoD and myogenin in human skeletal muscle fibres as well as the possible alterations in the expression of MyoD and myogenin in response to a single bout of endurance exercise at 40% and 75% of maximum oxygen uptake (VO(2) max). Twenty-five biopsies (5 per subject) from the vastus lateralis muscle were obtained before exercise, from the exercising leg at 40% and 75% of VO(2) max and from the resting leg following these exercise bouts. The tyramide signal amplification-direct and the Vectastain ABC methods using specific monoclonal antibodies were used to determine the exact location of myogenin and MyoD, to identify muscle satellite cells and to determine myosin heavy chain (MyHC) composition. At rest, myonuclei did not express MyoD or myogenin. Following a single bout of exercise at 40% and 75% of VO(2) max, an accumulation of myogenin in myonuclei and not in satellite cells was observed in biopsies from the exercised leg but not in biopsies before exercise and from the resting leg. The number of myogenin-positive myonuclei varied among individuals indicating differences in the response to a single exercise bout. In conclusion, this immunohistochemical study showed that a rapid rearrangement of myogenin expression occurs in exercised human skeletal muscles in response to a single bout of exercise.
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| 3. |
- Kadi, Fawzi, et al.
(författare)
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Satellite cells and myonuclei in young and elderly women and men
- 2004
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Ingår i: Muscle and Nerve. - : Wiley. - 0148-639X .- 1097-4598. ; 29:1, s. 120-127
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Tidskriftsartikel (refereegranskat)abstract
- The overall aim of this study was to assess the effects of aging on the satellite cell population. Muscle biopsies were taken from the tibialis anterior muscle of healthy, moderately active young (age range, 20-32 years; n = 31) and elderly (age range, 70-83 years; n = 27) women and men with comparable physical activity pattern. Satellite cells and myonuclei were visualized using a monoclonal antibody against neural cell adhesion molecule and counterstained with Mayer's hematoxylin. An average of 211 (range, 192-241) muscle fibers were examined for each individual. Compared with the young women and men, the elderly subjects had a significantly lower (P < 0.011) number of satellite cells per muscle fiber but a significantly higher (P < 0.004) number of myonuclei per muscle fiber. The number of satellite cells relative to the total number of nuclei [satellite cells/(myonuclei + satellite cells)] was significantly lower in the elderly than in the young women and men. These results imply that a reduction in the satellite cell population occurs as a result of increasing age in healthy men and women.
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- Kadi, Fawzi, et al.
(författare)
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The effects of heavy resistance training and detraining on satellite cells in human skeletal muscles
- 2004
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Ingår i: Journal of Physiology. - : Wiley. - 0022-3751 .- 1469-7793. ; 558:Pt 3, s. 1005-1012
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the modulation of satellite cell content and myonuclear number following 30 and 90 days of resistance training and 3, 10, 30, 60 and 90 days of detraining. Muscle biopsies were obtained from the vastus lateralis of 15 young men (mean age: 24 years; range: 20-32 years). Satellite cells and myonuclei were studied on muscle cross-sections stained with a monoclonal antibody against CD56 and counterstained with Mayer's haematoxylin. Cell cycle markers CyclinD1 and p21 mRNA levels were determined by Northern blotting. Satellite cell content increased by 19% (P= 0.02) at 30 days and by 31% (P= 0.0003) at 90 days of training. Compared to pre-training values, the number of satellite cells remained significantly elevated at 3, 10 and 60 days but not at 90 days of detraining. The two cell cycle markers CyclinD1 and p21 mRNA significantly increased at 30 days of training. At 90 days of training, p21 was still elevated whereas CyclinD1 returned to pre-training values. In the detraining period, p21 and CyclinD1 levels were similar to the pre-training values. There were no significant alterations in the number of myonuclei following the training and the detraining periods. The fibre area controlled by each myonucleus gradually increased throughout the training period and returned to pre-training values during detraining. In conclusion, these results demonstrate the high plasticity of satellite cells in response to training and detraining stimuli and clearly show that moderate changes in the size of skeletal muscle fibres can be achieved without the addition of new myonuclei.
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- Larsson, Britt, et al.
(författare)
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Blood supply and oxidative metabolism in muscle biopsies of female cleaners with and without myalgia
- 2004
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Ingår i: The Clinical Journal of Pain. - : Ovid Technologies (Wolters Kluwer Health). - 0749-8047 .- 1536-5409. ; 20:6, s. 440-446
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Pathomechanisms of work-related myalgia are poorly understood. Myalgia is thought to be caused by excitation of nociceptors present in the muscular tissue but not in the muscle fiber itself. Muscle contraction in combination with hypoxia is known to excite nociceptors. Morphologic analysis can contribute to the knowledge of the excitation of nociceptors. This study thoroughly examines the morphology of the trapezius muscle's capillary supply and signs of disturbed oxidative metabolism to understand their role in work-related myalgia. METHODS: Surgical trapezius muscle biopsies were obtained from 25 female cleaners with long-standing work-related myalgia, 25 female cleaners without trapezius myalgia, and 21 healthy teachers. Enzyme and immunohistochemical stainings were performed to highlight fibers with aberrant intermyofibrillar patterns, indicating a disturbed oxidative metabolism (also known as moth-eaten fibers) and a disturbed capillary supply of different fibers. RESULTS: A significantly lower number of capillaries per fiber area in cleaners suffering from myalgia compared with cleaners without trapezius myalgia was found. Moth-eaten fibers were found in the 3 groups, but these fibers were significantly more prevalent in the groups of cleaners than in the healthy teacher group. CONCLUSION: This work indicates that the capillary supply of trapezius is affected in work-related trapezius myalgia. More studies are needed to understand possible mechanisms that would explain the occurrence of moth-eaten fibers.
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- Nilsson, Andreas, 1973-, et al.
(författare)
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Assessing physical activity among children with accelerometers using different time sampling intervals and placements
- 2002
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Ingår i: Pediatric Exercise Science. - : Human Kinetics. - 0899-8493 .- 1543-2920. ; 14:1, s. 87-96
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Tidskriftsartikel (refereegranskat)abstract
- The aim was to investigate (a) the effect of five different time sampling intervals (epoch settings) on different intensity levels when assessing physical activity with an accelerometer (CSA, WAM 7164), and (b) whether the placement of the monitor (on the hip and back) would affect the outcome. Sixteen children (aged 7 yrs) were monitored for four consecutive days. A significant main epoch effect was found for time spent at very high (p < 01) and high (p < 01) intensity activities. No significant difference between the two placements regarding total amount of physical activity (cnts times mm super (-1)) or different intensity levels was observed. In conclusion, different time sampling intervals, but not placement, should be carefully considered when assessing physical activity.
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