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| 2. |
- Hodges, P W, et al.
(författare)
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In vivo measurement of the effect of intra-abdominal pressure on the human spine.
- 2001
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Ingår i: Journal of Biomechanics. - 0021-9290 .- 1873-2380. ; 34:3, s. 347-53
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Tidskriftsartikel (refereegranskat)abstract
- In humans, intra-abdominal pressure (IAP) is elevated during many everyday activities. This experiment aimed to investigate the extent to which increased IAP--without concurrent activity of the abdominal or back extensor muscles--produces an extensor torque. With subjects positioned in side lying on a swivel table with its axis at L3, moments about this vertebral level were measured when IAP was transiently increased by electrical stimulation of the diaphragm via the phrenic nerve. There was no electromyographic activity in abdominal and back extensor muscles. When IAP was increased artificially to approximately 15% of the maximum IAP amplitude that could be generated voluntarily with the trunk positioned in flexion, a trunk extensor moment (approximately 6 Nm) was recorded. The size of the effect was proportional to the increase in pressure. The extensor moment was consistent with that predicted from a model based on measurements of abdominal cross-sectional area and IAP moment arm. When IAP was momentarily increased while the trunk was flexed passively at a constant velocity, the external torque required to maintain the velocity was increased. These results provide the first in vivo data of the amplitude of extensor moment that is produced by increased IAP. Although the net effect of this extensor torque in functional tasks would be dependent on the muscles used to increase the IAP and their associated flexion torque, the data do provide evidence that IAP contributes, at least in part, to spinal stability.
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| 3. |
- Hodges, P W, et al.
(författare)
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Perturbed upper limb movements cause short-latency postural responses in trunk muscles.
- 2001
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Ingår i: Experimental Brain Research. - : Springer Science and Business Media LLC. - 0014-4819 .- 1432-1106. ; 138:2, s. 243-50
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Tidskriftsartikel (refereegranskat)abstract
- Addition of a load to a moving upper limb produces a perturbation of the trunk due to transmission of mechanical forces. This experiment investigated the postural response of the trunk muscles in relation to unexpected limb loading. Subjects performed rapid, bilateral shoulder flexion in response to a stimulus. In one third of trials, an unexpected load was added bilaterally to the upper limbs in the first third of the movement. Trunk muscle electromyography, intra-abdominal pressure and upper limb and trunk motion were measured. A short-latency response of the erector spinae and transversus abdominis muscles occurred approximately 50 ms after the onset of the limb perturbation that resulted from addition of the load early in the movement and was coincident with the onset of the observed perturbation at the trunk. The results provide evidence of initiation of a complex postural response of the trunk muscles that is consistent with mediation by afferent input from a site distant to the lumbar spine, which may include afferents of the upper limb.
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| 4. |
- Kemmer, D., et al.
(författare)
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Exploring the foundation of genomics : a Northern blot reference set for the comparative analysis of transcript profiling technologies
- 2004
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Ingår i: Comparative and functional genomics. - : Hindawi Limited. - 1531-6912 .- 1532-6268. ; 5:8, s. 584-595
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we aim to create a reference data collection of Northern blot results and demonstrate how such a collection can enable a quantitative comparison of modern expression profiling techniques, a central component of functional genomics studies. Historic ally, Northern blots were the de facto standard for determining RNA transcript levels. However, driven by the demand for analysis of large sets of genes in parallel, high-throughput methods, such as microarrays, dominate modern profiling efforts. To facilitate assessment of these methods, in comparison to Northern blots, we created a database of published Northern results obtained with a standardized commercial multiple tissue blot (dbMTN). In order to demonstrate the utility of the dbMTN collection for technology comparison, we also generated expression profiles for genes across a set of human tissues, using multiple profiling techniques. No method produced profiles that were strongly correlated with the Northern blot data. The highest correlations to the Northern blot data were determined with microarrays for the subset of genes observed to be specifically expressed in a single tissue in the Northern analyses. The database and expression profiling data are available via the project website (http://www.cisreg.ca). We believe that emphasis on multitechnique validation of expression profiles is justified, as the correlation results between platforms are not encouraging on the whole. Supplementary material for this article can be found at: http://www.interscience.wiley.com/jpages/1531-6912/suppmat
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