| 1. |
- 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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| 2. |
- Kadi, Fawzi, et al.
(författare)
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The behaviour of satellite cells in response to exercise : what have we learned from human studies?
- 2005
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Ingår i: Pflügers Archiv. - : Springer Science and Business Media LLC. - 0031-6768 .- 1432-2013. ; 451:2, s. 319-327
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Understanding the complex role played by satellite cells in the adaptive response to exercise in human skeletal muscle has just begun. The development of reliable markers for the identification of satellite cell status (quiescence/activation/proliferation) is an important step towards the understanding of satellite cell behaviour in exercised human muscles. It is hypothesised currently that exercise in humans can induce (1) the activation of satellite cells without proliferation, (2) proliferation and withdrawal from differentiation, (3) proliferation and differentiation to provide myonuclei and (4) proliferation and differentiation to generate new muscle fibres or to repair segmental fibre injuries. In humans, the satellite cell pool can increase as early as 4 days following a single bout of exercise and is maintained at higher level following several weeks of training. Cessation of training is associated with a gradual reduction of the previously enhanced satellite cell pool. In the elderly, training counteracts the normal decline in satellite cell number seen with ageing. When the transcriptional activity of existing myonuclei reaches its maximum, daughter cells generated by satellite cell proliferation are involved in protein synthesis by enhancing the number of nuclear domains. Clearly, delineating the events and the mechanisms behind the activation of satellite cells both under physiological and pathological conditions in human skeletal muscles remains an important challenge.
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| 3. |
- Ruiz, Jonatan R., et al.
(författare)
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Homocysteine levels in children and adolescents are associated with the methylenetetrahydrofolate reductase 677C>T genotype, but not with physical activity, fitness or fatness : the European Youth Heart Study
- 2007
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Ingår i: British Journal of Nutrition. - Cambridge : Cambridge university press. - 0007-1145 .- 1475-2662. ; 97:2, s. 255-262
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Tidskriftsartikel (refereegranskat)abstract
- To examine the associations of total plasma homocysteine (tHcy) with physical activity, cardiorespiratory fitness and fatness in children and adolescents, a cross-sectional study of 301 children (9–10 years old) and 379 adolescents (15–16 years old) was conducted. Physical activity was measured by accelerometry. Cardiorespiratory fitness was measured with a maximal ergometer bike test. Body fat was derived from the sum of five skinfold thicknesses. Genotyping for the methylenetetrahydrofolate reductase (MTHFR) 677C>T polymorphism was done by DNA sequencing. Fasting tHcy level was the outcome variable. Multiple regressions were used to determine the degree to which variance in tHcy was explained by physical activity, cardiorespiratory fitness and body fat, after controlling for potential confounders including MTHFR 677C>T genotype. tHcy levels were neither associated with any measure of level and pattern of physical activity nor with data on cardiorespiratory fitness, or body fat, in any age group after controlling for potential confounders including MTHFR 677C>T and even when subgroups 677TT and 677CC+CT were analysed separately. Mean values of tHcy were significantly higher in the TT subgroup compared with CC and CT subgroups in children (TT 7·4 μmol/l, CC 6·3 μmol/l, CT 6·6 μmol/l, P < 0·001 and P = 0·019, respectively) and adolescents (TT 16·9 μmol/l, CC 8·3 μmol/l, CT 9·0 μmol/l, both P < 0·001). The results suggest that physical activity, fitness and body fat are not associated with tHcy levels in children and adolescents, even after controlling for presence of the MTHFR 677C>T genotype, the main influence on tHcy levels in these subjects.
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| 4. |
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| 5. |
- Tedersoo, Leho, et al.
(författare)
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Response to Comment on “Global diversity and geography of soil fungi”
- 2015
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 349:6251
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Schadt and Rosling (Technical Comment, 26 June 2015, p. 1438) argue that primer-template mismatches neglected the fungal class Archaeorhizomycetes in a global soil survey. Amplicon-based metabarcoding of nine barcode-primer pair combinations and polymerase chain reaction (PCR)–free shotgun metagenomics revealed that barcode and primer choice and PCR bias drive the diversity and composition of microorganisms in general, but the Archaeorhizomycetes were little affected in the global study. We urge that careful choice of DNA markers and primers is essential for ecological studies using high-throughput sequencing for identification.
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| 6. |
- Jörntell, Henrik, et al.
(författare)
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Reciprocal bidirectional plasticity of parallel fiber receptive fields in cerebellar Purkinje cells and their afferent interneurons.
- 2002
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Ingår i: Neuron. - 0896-6273. ; 34:5, s. 797-806
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Tidskriftsartikel (refereegranskat)abstract
- The highly specific relationships between parallel fiber (PF) and climbing fiber (CF) receptive fields in Purkinje cells and interneurons suggest that normal PF receptive fields are established by CF-specific plasticity. To test this idea, we used PF stimulation that was either paired or unpaired with CF activity. Conspicuously, unpaired PF stimulation that induced long-lasting, very large increases in the receptive field sizes of Purkinje cells induced long-lasting decreases in receptive field sizes of their afferent interneurons. In contrast, PF stimulation paired with CF activity that induced long-lasting decreases in the receptive fields of Purkinje cells induced long-lasting, large increases in the receptive fields of interneurons. These properties, and the fact the mossy fiber receptive fields were unchanged, suggest that the receptive field changes were due to bidirectional PF synaptic plasticity in Purkinje cells and interneurons.
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| 7. |
- 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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| 8. |
- Kadi, Fawzi, et al.
(författare)
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The number of satellite cells in slow and fast fibres from human vastus lateralis muscle
- 2006
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Ingår i: Histochemistry and Cell Biology. - : Springer Science and Business Media LLC. - 0948-6143 .- 1432-119X. ; 126:1, s. 83-87
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this investigation was to study the distribution of satellite cells in slow (type I fibres) and fast (type II fibres) fibres from human vastus lateralis muscle. This muscle is characterised by a mixed fibre type composition and is considered as the site of choice for biopsies in research work and for clinical diagnosis. Biopsy samples were obtained from five healthy young volunteers and a total of 1,747 type I fibres and 1,760 type II fibres were assessed. Satellite cells and fibre type composition were studied on serial muscle cross-sections stained with specific monoclonal antibodies. From a total of 218 satellite cells, 116 satellite cells were found in contact with type I fibres (53.6+/-8% of the satellite cells associated to type I fibres) and 102 satellite cells in contact with type II fibres (46.4+/-8% of the satellite cells associated to type II fibres). There was no significant difference (P=0.4) between the percentages of satellite cells in contact with type I and with type II fibres. Additionally, there was no relationship between the mean number of satellite cells per fibre and the mean cross-sectional area of muscle fibres. In conclusion, our results show that there is no fibre type-specific distribution of satellite cells in a human skeletal muscle with mixed fibre type composition.
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| 9. |
- Pontén, Eva, et al.
(författare)
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Higher amount of MyHC IIX in a wrist flexor in tetraplegic compared to hemiplegic cerebral palsy
- 2008
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Ingår i: Journal of the Neurological Sciences. - : Elsevier. - 0022-510X .- 1878-5883. ; 266:1-2, s. 51-56
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Spastic cerebral palsy can be divided into diagnostic groups by the relative severity of the arm impairment. This study investigates if hemiplegic, tetraplegic or diplegic cerebral palsy (CP) results in different patterns of myosin heavy chain (MyHC) expression in the flexor carpi ulnaris muscle from 17 young patients with CP. Using enzyme-immunohistochemistry and gel electrophoresis techniques we found a higher percentage of fibers expressing fast MyHC IIx (52%) in tetraplegic CP compared to hemiplegic patients (32%), (p < 0.05). Tetraplegic CP also resulted in a lower amount of fibers expressing slow MyHC I (18%) compared to hemiplegic CP (40%), (p < 0.005). The proportion of muscle fibers containing fetal MyHC was higher in tetraplegic CP compared to other groups, (p < 0.005). Taken together theses results indicate that tetraplegic CP is associated with a shift from slow to fast myosins and that regenerative events are more prominent in tetraplegic CP compared with milder brain damage.
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| 10. |
- Verney, Julien, et al.
(författare)
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Combined lower body endurance and upper body resistance training improves performance and health parameters in healthy active elderly
- 2006
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 97:3, s. 288-297
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We investigated the effects of combined lower body (LB) endurance and upper body (UB) resistance training on endurance, strength, blood lipid profile and body composition in active older men. Ten healthy still active men (73+/-4 years, V(O2) peak: 36 (31-41) ml min-1 kg-1) were tested before and after 14 weeks of combined training (3 times week-1). Training consisted of 3x12 min of high intensity interval training on a bicycle for endurance interspersed by 3x12 min of UB resistance exercises. V(O2) peak during leg cycling and arm cranking, isokinetic torque of knee extensor and shoulder abductor and the cross-sectional area (CSA) of several muscles from UB and LB were measured. Sagittal abdominal diameter (SAD) and abdominal fat area were measured on MRI scans. Total body composition was assessed by hydrostatic weighing (HW) and dual-energy X-ray absorptiometry (DEXA). Blood lipid profile was assessed before and after training. By the end of the training period, V(O2) peak (l min-1) increased significantly by 9 and 16% in leg cycling and arm cranking tests, respectively. Maximal isokinetic torque increased both for the knee extensor and shoulder abductor muscle groups. CSA increased significantly in deltoid muscle. Percentage of body fat decreased by 1.3% (P<0.05) and abdominal fat and SAD decreased by 12 and 6%, respectively (P<0.01). There was also a significant decrease in total cholesterol and low-density lipoprotein. Thus, combined LB endurance and UB resistance training can improve endurance, strength, body composition and blood lipid profile even in healthy active elderly.
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