| 1. |
- Downham, David, et al.
(author)
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Distribution of different fibre types in human skeletal muscles: A method for the detection of neurogenic disorders
- 1987
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In: IMA journal of mathematics applied in medicine and biology. - : Oxford University Press (OUP). - 0265-0746 .- 1471-6879. ; 4:1, s. 81-91
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Journal article (peer-reviewed)abstract
- Human skeletal muscles are composed of two distinguishable types of fibres, which in healthy muscles appear to be randomly arranged. Large groups of one fibre type are commonly regarded as evidence of a neuropathological process affecting the peripheral nerves or the nerve cells in the spinal cord. An objective method that detects non-random arrangements as a sign of a neurogenic disorder, particularly in its early stages, could improve diagnosis. The randomness, or otherwise, of the fibre type arrangement is here considered in terms of the numbers of fibres surrounded entirely by others of the same type (enclosed fibres). The distribution of the number of enclosed fibres is studied for a free-sampling model using Monte Carlo methods. The negative binomial distribution is shown to fit closely, where the parameters can be expressed in terms of the number of fibres and the fibre type proportion in a sample area. This result permits the calculation of significance levels for a sample area and the combination of information in several sample areas. Finally, the method is applied to whole cross-sections of 24 male human autopsied muscles.
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| 2. |
- Edman, Anne-Christine, 1946-
(author)
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Myofibrillens finstruktur i tvärstrimmig skelettmuskulatur
- 1988
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Doctoral thesis (other academic/artistic)abstract
- The detailed structure of the myofibrillar material in fibres from different muscles has been studied. Specimens have been obtained from human muscles and from different muscles frequently examined in experimental studies. Both light- and electron microscopical techniques have been used. Of central importance has been the method, which makes it possible to prepare ultrathin sections of frozen tissue, i.e. cryo-ult- ramicrotomy. A number of techniques for image analysis have been applied in order to obtain objektive data from the micrographs.In Paper I the present knowledge about muscle fibre structure, cryo-- sectioning and image analysis is summarized and relevant methodological problems are discussed. Paper II describes the detailed structure of the C-zone of the A-band and shows, above all, that structures occur with different repeats along the long axis of the myofibril. Paper III describes the subcellular organization of different fibres in a homogeneous (based on enzyme histochemical mATPase) population, and shows that different structural characteristies can vary independently of each other. Paper IV describes the structural diversity of the myofibrillar M-band, and paper V the diversity of the myofilament fine structure in different fibres. The results show that there is a most sophisticated, and previosly unrealized, structural specialization both within the myofibrils and between myofibrils from different fibres and muscles, even if the fibres are of the same fibre type. The findings suggest that generally used models, showing the structural organization within myofibrils and myofilaments, are oversimplifications. The fibre population is more heterogeneously built up than the common systems for fibre type classification makes one to belive.
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| 3. |
- Edman, Anne-Christine, et al.
(author)
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Structural diversity in muscle fibres of chicken breast
- 1988
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In: Cell and Tissue Research. - 0302-766X .- 1432-0878. ; 251:2, s. 281-289
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Journal article (peer-reviewed)abstract
- hicken breast muscle is usually considered to be a relatively homogeneous white muscle and has therefore been widely used for studies of muscle proteins. In a previous study, however, we have found different M-region structures in different fibres from this muscle. Because of this result, we have now carried out a combined histochemical and ultrastructural survey of this muscle. In particular, we have made use of large transverse cryo-sections that include most of the muscle cross-section. Although the white region is fairly homogeneous in fibre content according to normal histochemical criteria (mATPase), we have found that there is a gradation of fibre structure across the muscle. The bulk of the muscle stains conventionally for Type-II fibres according to mATPase tests (the "white" part) but, in the small "red" part of the muscle, there are also Type-I fibres together with the Type-II fibres. Superimposed on this division into Type-I and Type-II fibres are variations in fibre size, oxidative and glycolytic staining properties, and variations of Z-band width and M-band structure; there is no strict correlation among any of these parameters. The apparently uniform staining across most of the muscle when tested for myofibrillar ATPase may be a misleading indicator of fibre properties.
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| 4. |
- Lexell, Jan, et al.
(author)
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Distribution of different fibre types in human skeletal muscles : fibre type arrangement in m. vastus lateralis from three groups of healthy men between 15 and 83 years
- 1986
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In: Journal of the Neurological Sciences. - 0022-510X .- 1878-5883. ; 72:2-3, s. 211-222
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Journal article (peer-reviewed)abstract
- The effects of age on the fibre type arrangement in the human muscle m. vastus lateralis were studied. There were 10, 6 and 8 healthy men in the three age-groups with means 24, 52 and 77 years, respectively. For each fascicle considered, the numbers of type 1 (ST) and type 2 (FT) fibres on the boundary and internally, and the numbers of enclosed fibres of either type, were counted. The randomness of the fibre type arrangement was considered in terms of the numbers of enclosed fibres and assessed by a Monte Carlo significance test. Fibre type grouping was shown to increase with increasing age. The proportion of type 2 fibres on the boundary of a fascicle was consistently greater than internally, but the difference was less pronounced in the old group. It is argued that the process of denervation and reinnervation of individual fibres has started before the age of 50, is a major factor in a progressive reduction of fibres with increasing age and is probably caused by a continuous loss of motor neurons in the spinal cord.
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| 5. |
- Lexell, Jan, et al.
(author)
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Morphological detection of neurogenic muscle disorders : how can statistical methods aid diagnosis?
- 1987
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In: Acta Neuropathologica. - 0001-6322 .- 1432-0533. ; 75:2, s. 109-115
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Journal article (peer-reviewed)abstract
- The light microscopical observation of groups of histochemically similar muscle fibres, referred to as fibre-type grouping, is commonly considered to be evidence of a denervation and reinnervation process affecting the spinal motor neurons or the peripheral nerves. It can be difficult to assess whether such groups have occurred by chance or are due to a slowly progressive pathological process in an early stage of development. Consequently, there is a need for one or more objective methods for assessing the fibre-type arrangement in healthy and diseased human muscles. The purposes here are to review the methods for the detection of fibre-type grouping that have been published in the last two decades, to describe some unsolved problems, and to indicate some likely lines of development
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| 6. |
- Lexell, Jan, et al.
(author)
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What is the cause of the ageing atrophy? : number, size and proportion of different fiber types studied in whole vastus lateralis muscle from 15- to 83-year-old men
- 1988
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In: Journal of the Neurological Sciences. - 0022-510X .- 1878-5883. ; 84:2-3, s. 275-294
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Journal article (peer-reviewed)abstract
- In order to study the effects of increasing age on the human skeletal muscle, cross-sections (15 micron) of autopsied whole vastus lateralis muscle from 43 previously physically healthy men between 15 and 83 years of age were prepared and examined. The data obtained on muscle area, total number, size, proportion and distribution of type 1 (slow-twitch) and type 2 (fast-twitch) fibers were analysed using multivariate regression. The results show that the ageing atrophy of this muscle begins around 25 years of age and thereafter accelerates. This is caused mainly by a loss of fibers, with no predominant effect on any fiber type, and to a lesser extent by a reduction in fiber size, mostly of type 2 fibers. The results also suggest the occurrence of several other age-related adaptive mechanisms which could influence fiber sizes and fiber number, as well as enzyme histochemical fiber characteristics
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| 7. |
- Sjöström, Michael, et al.
(author)
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Distribution of different fiber types in human skeletal muscles : why is there a difference within a fascicle?
- 1986
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In: Muscle and Nerve. - : Wiley. - 0148-639X .- 1097-4598. ; 9:1, s. 30-36
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Journal article (peer-reviewed)abstract
- The proportions of different fiber types (type 1 and type 2) on the borders of fascicles are shown to differ from the proportions internally. This finding is based on the analysis of a total of 245 fascicles from whole cross-sections of the vastus lateralis muscle from 13 men, aged from 26-80 years. Generally, the difference is more marked in the young than in the old. It is argued that the causes of this difference are likely to be local factors in the muscle.
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| 8. |
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| 9. |
- Wilson, B.C., et al.
(author)
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Some probability models for diagnosing neurogenic disorders
- 1988
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In: IMA journal of mathematics applied in medicine and biology. - : Oxford University Press (OUP). - 0265-0746 .- 1471-6879. ; 5:3, s. 167-179
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Journal article (peer-reviewed)abstract
- Healthy human skeletal muscles are composed of two distinguishable types of fibre, apparently randomly arranged within fascicles (bundles of fibres surrounded by connective tissue). Large groups of fibres of the same type indicate a neurogenic muscle disorder. An objective method for detecting nonrandom arrangements of fibres could improve the diagnosis of such disorders, particularly at an early stage. The number of enclosed fibres (NEF)--fibres surrounded by others of the same type--is considered here as a measure of nonrandomness. The distribution of NEF is shown to be approximately negative binomial for a non-free-sampling model, which is then compared with a free-sampling model studied previously. A modification for a known boundary effect is also investigated. The models are applied to data from m. vastus lateralis obtained post mortem from 24 previously healthy men. Finally, the relationship between size of biopsy and the accuracy of predictions is discussed.
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