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- Ekström, Lars, 1959, et al.
(författare)
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In vivo porcine intradiscal pressure as a function of external loading
- 2004
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Ingår i: J Spinal Disord Tech. - 1536-0652. ; 17:4, s. 312-6
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Spinal loading during daily activity as it relates to the ability of the intervertebral disc to sustain its integrity has been a major issue in spinal research. The purpose of this investigation was to establish the relationship between the intervertebral disc pressure in the nucleus and the load applied to the motion segment in an in vivo porcine model. METHODS: Nine domestic pigs were used in this study. A miniaturized servohydraulic testing machine was affixed to the lumbar spine via four intrapedicular screws, which were inserted bilaterally into the L2 and L3 vertebrae. A pressure needle was inserted through the lateral part of the L2-L3 disc annulus and into the nucleus pulposus. Force, deformation, and intradiscal pressure data were collected during a loading scheme that consisted of applying a set of constant loads in increasing order, that is, 50, 100, 150, 200, and 250 N. Each load was applied for 30 seconds followed by 30-second restitution. RESULTS: Intradiscal nucleus pressure was found to correlate to the applied load in all cases. Linear regression analyses resulted in the following equation: intradiscal pressure (MPa) = 0.08 + 1.25E(-3)(load, N), r(2) = 0.81, n = 8. Intradiscal pressure was also highly linearly dependent on the stress. The intrinsic intradiscal pressure was found to be 81 +/- 5 kPa. The results also indicated that the pressure within the disc exhibited a creep behavior. CONCLUSION: In conclusion, pressure in the nucleus of the porcine intervertebral disc was linearly related to the applied load and stress.
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- Enevoldsen, L.H., et al.
(författare)
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The effect of exercise training on hormone-sensitive lipase in rat intra-abdominal adipose tissue and muscle
- 2001
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Ingår i: Journal of Physiology. - : Wiley. - 1469-7793 .- 0022-3751. ; 536:3, s. 871-877
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Tidskriftsartikel (refereegranskat)abstract
- 1. Adrenaline-stimulated lipolysis in adipose tissue may increase with training. The rate-limiting step in adipose tissue lipolysis is catalysed by the enzyme hormone-sensitive lipase (HSL). We studied the effect of exercise training on the activity of the total and the activated form of HSL, referred to as HSL (DG) and HSL (TG), respectively, and on the concentration of HSL protein in retroperitoneal (RE) and mesenteric (ME) adipose tissue, and in the extensor digitorum. longus (EDL) and soleus muscles in rats. 2. Rats (weighing 96 + 1 g, mean +/- S.E.M.) were either swim trained (T, 18 weeks, n = 12) or sedentary (S, n = 12). Then RE and ME adipose tissue and the EDL and soleus muscles were incubated for 20 min with 4.4 muM adrenaline. 3. HSL enzyme activities in adipose tissue were higher in T compared with S rats. Furthermore, in RE adipose tissue, training also doubled HSL protein concentration (P < 0.05). In ME adipose tissue, the HSL protein levels did not differ significantly between T and S rats. In muscle, HSL (TG) activity as well as HSL (TG)/HSL (DG) were. lower in T rats, whereas HSL (DG) activity did not differ between groups. Furthermore, HSL protein concentration in muscle did not differ between T and S rats (P > 0.05). 4. In conclusion, training increased the amount of HSL and the sensitivity of HSL to stimulation by adrenaline in intra-abdominal adipose tissue, the extent of the change differing between anatomical locations. In contrast, in skeletal muscle the amount of HSL was unchanged and its sensitivity to stimulation by adrenaline reduced after training.
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- Holm, Sten, 1948, et al.
(författare)
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Experimental disc degeneration due to endplate injury
- 2004
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Ingår i: J Spinal Disord Tech. - 1536-0652. ; 17:1, s. 64-71
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to create an experimental model of disc degeneration that closely mimicked human disc degeneration. In six domestic pigs, an L4 cranial endplate perforation into the nucleus pulposus was made. Three months postoperatively, compressive testing was performed on the L2-L4 motion segments, and intradiscal pressure was measured in the intervening discs. Histochemical and morphologic examinations were made on the excised degenerated and adjacent discs. A significant reduction in water content was observed in the outer anterior annulus of the degenerated disc. In the nucleus, the proteoglycan content was significantly reduced, as well as the cellularity, although not significantly. The nucleus lost its gel-like structure and was discolored, and there was delamination of annular layers. Intradiscal pressure in the nucleus was significantly lower in the degenerated disc. In conclusion, experimental degeneration of the intervertebral disc induced by endplate penetration resembled human disc degeneration, as exemplified by biochemical and structural changes.
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| 9. |
- Boiesen, P, et al.
(författare)
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Histologic grading in breast cancer--reproducibility between seven pathologic departments. South Sweden Breast Cancer Group
- 2000
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Ingår i: Acta Oncologica. - : Informa UK Limited. - 1651-226X .- 0284-186X. ; 39:1, s. 41-45
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Tidskriftsartikel (refereegranskat)abstract
- Histologic grade, including tubular formations, nuclear grade, and mitotic activity, is a well-documented prognostic factor in breast cancer. In comparison with other prognostic parameters, the evaluation of histologic grade is cheap and can be performed, in principle, in all cases of breast cancer. One possible disadvantage is that the evaluation may vary between different pathological departments. The aim of the present work was therefore to study the reproducibility of the histologic grading system by distributing haematoxylin-erythrosin-stained slides from 93 invasive breast cancers to the seven pathology departments within the southern healthcare region of Sweden. The evaluation was performed blindly and without any knowledge of other clinical parameters. In 31% of the cases the same histologic grade was obtained for all departments. The overall mean kappa was 0.54, indicating a moderate reproducibility. Of the three factors included in histologic grade, the agreement was best for tubular formations and poorest for nuclear grade and mitotic activity. The overall moderate reproducibility should be considered when the clinical usefulness of histologic grading is compared with other prognostic instruments.
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- Brinck, Tore, et al.
(författare)
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Solvation of sulfur-centered cations and anions in acetonitrile
- 2002
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Ingår i: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 106:37, s. 8827-8833
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Tidskriftsartikel (refereegranskat)abstract
- The solvation of substituted phenylsulfenium ions and thiophenoxides in acetonitrile has been analyzed on the basis of experimental and theoretical data. Experimental solvation energies are obtained from previously reported oxidation and reduction potentials of the corresponding arylthiyl radicals in combination with theoretically calculated ionization potentials and electron affinities at the B3LYP/6-31+G(d) level. These calculations provide a consistent set of values in contrast to the data sets obtained in our previous paper (Larsen et al., J. Am. Chem. Soc. 2001, 123, 1723). The extracted solvation data show the expected substituent dependency for both kinds of ions, i.e., the absolute value of the solvation energy decreases as the charge becomes more delocalized. For the thiophenoxides there is good agreement between the experimental solvation energies and solvation energies computed using the polarizable continuum model (PCM). The solvation of the arylsulfenium ions, is much stronger than predicted by the PCM method. This can be attributed to the formation of a strong covalent bond of the Ritter type between the arylsulfenium ion and one molecule of acetonitrile. When this interaction is included in the solvation energy calculations by means of a combined supermolecule and PCM approach the experimental data are reproduced within a few kcal mol(-1). While the energy difference of the singlet and triplet spin states of the arylsulfenium ions is almost negligible in gas phase, the singlet cation is undoubtedly the dominating species in solution, since the triplet cation lacks the ability to form a covalent bond with acetonitrile.
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