| 1. |
- Degens, H, et al.
(författare)
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Application of skinned singel muscle fibres to determine myofilament function in ageing and disease
- 2007
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Ingår i: Journal of Musculoskeletal and Neuronal Interactions - JMNI. - 1108-7161. ; 7:1, s. 56-61
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Tidskriftsartikel (refereegranskat)abstract
- The chemically skinned fibre is a suitable preparation to determine whether alterations in myofilament function contributeto muscle dysfunction during ageing and disorders such as chronic obstructive pulmonary disease (COPD). In this preparationthe sarcolemma is chemically permeabilized and the myofilament lattice kept intact, functioning under controlled near-phys-iological conditions. As force generating capacity is an important determinant of muscle function and is related to fibre cross-sectional area (FCSA), we compared several methods employed by researchers to determine FCSA. Specific tension, forcedivided by FCSA, has a co-efficient of variation of 27%, 37%, or 30% when the FCSA was measured from the width and depthassuming an elliptical circumference, the width assuming a circular circumference, and the width while the fibre was suspend-ed in the air, respectively. The last method showed the closest relation with the FCSA in histological sections. The velocity ofmaximal unloaded shortening (V0) varied with fibre type, with fibres expressing the ‚/slow (type I) myosin heavy chain(MyHC) isoform being the slowest and fibres expressing the IIb MyHC isoform the fastest. While muscle weakness experi-enced after surgery could not be explained by changes in specific tension or FCSA of individual fibres, the preparationrevealed significant changes in myofilament function during ageing and COPD.
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| 2. |
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| 3. |
- Degens, H, et al.
(författare)
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Post-operative effects on insulin resistance and specific tension of single human skeletal muscle fibres
- 1999
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Ingår i: Clinical science (London, England : 1979). - : Portland Press Ltd.. - 0143-5221 .- 1470-8736. ; 97:4, s. 449-455
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Tidskriftsartikel (refereegranskat)abstract
- Surgery and accidental trauma are associated with a transient period of insulin resistance, substrate catabolism and muscle weakness. In the present study, we evaluated the changes in the force-generating capacity of chemically skinned single muscle fibres following abdominal surgery. Biopsies of the m. vastus lateralis were obtained in three patients 1 day before and 3 or 6 days after surgery. Part of the biopsy was frozen for histochemical analysis of the fibre cross-sectional area (FCSA) and myofibrillar protein content, and another part was used for single-fibre contractile measurements. All patients developed insulin resistance following surgery. The maximum velocity of unloaded shortening of single muscle fibres did not change following surgery. The FCSA did not decrease after surgery, as determined either from histochemical sections or from single fibres measured at a fixed sarcomere length of 2.76±0.09 μm (mean±S.D.). Further, the force-generating capacity of the single fibres, measured as maximal Ca2+-activated force (P0) or as P0 normalized to FCSA (specific tension), remained unchanged, as did the myofibrillar protein content of the muscle. In conclusion, the muscle weakness associated with post-operative insulin resistance is not related to a decreased specific tension or a loss of myofibrillar proteins. Other potential cellular mechanisms underlying post-operative weakness are discussed.
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| 4. |
- Díaz, Miguel, Högskoleadjunkt, et al.
(författare)
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Acute resveratrol supplementation in coronary artery disease : towards patient stratification
- 2020
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Ingår i: Scandinavian Cardiovascular Journal. - : Taylor & Francis. - 1401-7431 .- 1651-2006. ; :1, s. 14-19
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Resveratrol (RV) is a polyphenol with antioxidant, anti-inflammatory and cardio-protective properties. Our objective was to investigate whether acute supplementation with high doses of RV would improve flow-mediated dilation (FMD) and oxygen consumption (VO2) kinetics in older coronary artery disease (CAD) patients.DESIGN: We employed a placebo-controlled, single-blind, crossover design in which ten participants (aged 66.6 ± 7.8 years) received either RV or placebo (330 mg, 3x day-1) during three consecutive days plus additional 330 mg in the morning of the fourth day with a seven-day wash-out period in-between. On the fourth day, FMD of the brachial artery and VO2 on-kinetics were determined. Results; RV improved FMD in patients who had undergone coronary artery bypass grafting (CABG; -1.4 vs. 5.0%; p = 0.004), but not in those who had undergone percutaneous coronary intervention (PCI; 4.2 vs. -0.2%; NS).CONCLUSION: Acute high dose supplementation with RV improved FMD in patients after CABG surgery but impaired FMD in patients who underwent PCI. The revascularization method-related differential effects of RV may be due to its direct effects on endothelial-dependent dilator responses. Our findings have important implications for personalized treatment and stratification of older CAD patients.
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| 5. |
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| 6. |
- Larsson, L, et al.
(författare)
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Sarcopenia: Aging-Related Loss of Muscle Mass and Function
- 2019
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Ingår i: Physiological reviews. - : American Physiological Society. - 1522-1210 .- 0031-9333. ; 99:1, s. 427-511
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Tidskriftsartikel (refereegranskat)abstract
- Sarcopenia is a loss of muscle mass and function in the elderly that reduces mobility, diminishes quality of life, and can lead to fall-related injuries, which require costly hospitalization and extended rehabilitation. This review focuses on the aging-related structural changes and mechanisms at cellular and subcellular levels underlying changes in the individual motor unit: specifically, the perikaryon of the α-motoneuron, its neuromuscular junction(s), and the muscle fibers that it innervates. Loss of muscle mass with aging, which is largely due to the progressive loss of motoneurons, is associated with reduced muscle fiber number and size. Muscle function progressively declines because motoneuron loss is not adequately compensated by reinnervation of muscle fibers by the remaining motoneurons. At the intracellular level, key factors are qualitative changes in posttranslational modifications of muscle proteins and the loss of coordinated control between contractile, mitochondrial, and sarcoplasmic reticulum protein expression. Quantitative and qualitative changes in skeletal muscle during the process of aging also have been implicated in the pathogenesis of acquired and hereditary neuromuscular disorders. In experimental models, specific intervention strategies have shown encouraging results on limiting deterioration of motor unit structure and function under conditions of impaired innervation. Translated to the clinic, if these or similar interventions, by saving muscle and improving mobility, could help alleviate sarcopenia in the elderly, there would be both great humanitarian benefits and large cost savings for health care systems.
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