| 1. |
- Lexell, Jan, et al.
(författare)
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Distribution of different fibre types in human skeletal muscles : A statistical and computational study of the fibre type arrangement in m. vastus lateralis of young, healthy males
- 1984
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Ingår i: Journal of the Neurological Sciences. - 0022-510X .- 1878-5883. ; 65:3, s. 353-365
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Tidskriftsartikel (refereegranskat)abstract
- To test whether the arrangement of fibre types in the human muscle (m. vastus lateralis) from clinically healthy and young males can be regarded as random, fascicles at different parts of the muscle and with different fibre type proportions were studied. The randomness of the arrangement of fibre types was assessed by the number of enclosed fibres in a fascicle and, on the basis of a model, tested by simulating muscle cross-sections using a microcomputer. The fibre type proportion was found to vary within a fascicle, so the original model for the test of randomness was modified to allow for different fibre type proportions on the border of the fascicle and internally. The effect of different sizes of the fibre types was also considered. The various aspects considered had only a marginal effect on the original model. For this muscle (m. vastus lateralis) the arrangement of fibre types was therefore considered random. Thus, a sample from this muscle, taken from individuals of the same sex and age group, can be tested for non-randomness, as an indication of a successive denervation and reinnervation process
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| 2. |
- Lexell, Jan, et al.
(författare)
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Distribution of different fibre types in human skeletal muscles. A statistical and computational model for the study of fibre type grouping and early diagnosis of skeletal muscle fibre denervation and reinnervation
- 1983
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Ingår i: Journal of the Neurological Sciences. - 1878-5883 .- 0022-510X. ; 61:3, s. 301-314
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Tidskriftsartikel (refereegranskat)abstract
- To define fibre type grouping in terms of random and non-random arrangements of the two fibre types, type 1 (ST) and type 2 (FT), we adopted the measure of counting the number of "enclosed fibres". The statistical properties of the number of enclosed fibres, and the number and size of groups of enclosed fibres were studied in computer-simulated muscle cross-sections, using a model based upon hexagonal-shaped fibres. The effects on the results of differences in the sizes of the muscle fibres were considered. The applicability of the model, and the derived results and methods of analysis were tested on 10 samples from a cross-section of a whole human muscle. The results show that the model can be applied to various shapes and sizes of muscle samples and various sizes of muscle fibres. The number of enclosed fibres within a muscle sample is the best of the three measures of non-randomness considered. A test is also described for assessing whether or not the observed number of enclosed fibres is random at a given significance level.
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| 3. |
- Libelius, Rolf, et al.
(författare)
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Uptake of horseradish peroxidase in denervated skeletal muscle occurs primarily at the endplate region
- 1984
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Ingår i: Journal of the Neurological Sciences. - 0022-510X .- 1878-5883. ; 66, s. 273-281
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Tidskriftsartikel (refereegranskat)abstract
- The spatial distribution of horseradish peroxidase (HRP) uptake has been studied by light- and electron microscopy in the denervated hemidiaphragm of the mouse. Segments with high HRP uptake were observed in a band centrally located in the denervated muscle. This distribution is similar to the well-known innervation pattern of the diaphragm. Ultrastructural studies demonstrated a high incidence of postsynaptic folds in close proximity of fibre areas with high intracellular content of HRP. 8–12 days after denervation a large number of fibres showed segments of high HRP uptake. 2–4 days after denervation very few such segments were observed. Biochemical studies also demonstrated an increase in HRP uptake after denervation occurring primarily in the endplate region. The activities of the lysosomal enzymes N-acetyl-β-d-glucosaminidase, acid phosphatase and cathepsin D all increased after denervation, most prominently in the endplate region.It is suggested that the observed segmental uptake of HRP and lysosomal activation reflects a process for rapid membrane turnover in denervated muscle.
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