| 11. |
- Halfvarson, Jonas, 1970-, et al.
(författare)
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CARD15/NOD2 polymorphisms do not explain concordance of Crohn´s disease in Swedish monozygotic twins
- 2005
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Ingår i: Digestive and Liver Disease. - : Elsevier BV. - 1590-8658 .- 1878-3562. ; 37:10, s. 768-762
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: CARD15/NOD2 polymorphisms are associated with Crohn's disease. There is a high concordance for disease and disease phenotype in monozygotic twin pairs with Crohn's disease.AIM: We studied CARD15/NOD2 polymorphisms in a Swedish, population-based cohort of monozygotic twins with Crohn's disease to assess whether these variants explain disease concordance.SUBJECTS AND METHODS: Twenty-nine monozygotic twin pairs (concordant n=9, discordant n=20) with Crohn's disease and 192 healthy controls were investigated for the CARD15/NOD2 variants Arg702Trp, Gly908Arg and Leu1007fsinsC.RESULTS: CARD15/NOD2 mutations were found in 5/38 (13%) twins with Crohn's disease, corresponding to a total allele frequency of 6.6%. Only 2/9 concordant twin pairs carried any of the variants and the remaining seven were wild type genotype. The total allele frequency was 4.4 times higher (95% confidence interval 1.0-21.5, p=0.06) in concordant twins than in discordant ones, 11.1% versus 2.5%. In healthy controls the total allele frequency was 2.6%.CONCLUSIONS: CARD15/NOD2 polymorphisms contribute but do not alone explain concordance of Crohn's disease in monozygotic twins and, at least in a Swedish population, other polymorphisms are required. The low occurrence of CARD15/NOD2 mutations in the study and other Northern European populations suggests that these variants are of less importance in Northern Europe.
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| 12. |
- Helmrot, Ebba, et al.
(författare)
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Estimation of the dose to the unborn child at diagnostic X-ray examinations based on data registrerad in RIS/PACS
- 2007
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Ingår i: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; 17:1, s. 205-209
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to determine mean absorbed doses to the unborn child in common conventional X-ray and computed tomography (CT) examinations and to find an approach for estimating foetal dose based on data registered in the Radiological Information System/Picture Archive and Communication System (RIS/PACS). The kerma-area product (KAP) and CT dose index (CTDIvol) in common examinations were registered using a human-shaped female dosimetry phantom. Foetal doses, Df, were measured using thermoluminescent dosimeters placed inside the phantom and compared with calculated values. Measured foetal doses were given in relation to the KAP and the CTDIvol values, respectively. Conversion factor Df/KAP varies between 0.01 and 3.8 mGy/Gycm2, depending on primary beam position, foetus age and beam quality (tube voltage and filtration). Conversion factors Df/CTDIvol are in the range 0.02 – 1.2 mGy/mGy, in which the foetus is outside or within the primary beam. We conclude that dose conversion factors based on KAP or CTDIvol values automatically generated by the RIS/PACS system can be used for rapid estimations of foetal dose for common examination techniques.
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| 13. |
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| 14. |
- Hultqvist, Adam, et al.
(författare)
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CuGaSe2 solar cells using atomic layer deposited Zn(O,S) and (Zn,Mg)O buffer layers
- 2009
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 517:7, s. 2305-2308
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Tidskriftsartikel (refereegranskat)abstract
- The band gap of Zn(O,S) and (Zn,Mg)O buffer layers are varied with the objective of changing the conduction band alignment at the buffer layer/CuGaSe2 interface. To achieve this, alternative buffer layers are deposited using atomic layer deposition. The optimal compositions for CuGaSe2 solar cells are found to be close to the same for (Zn,Mg)O and the same for Zn(O,S) as in the CuIn0.7Ga0.3Se2 solar cell case. At the optimal compositions the solar cell conversion efficiency for (Zn,Mg)O buffer layers is 6.2% and for Zn(O,S) buffer layers it is 3.9% compared to the CdS reference cells which have 5-8% efficiency.
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| 15. |
- Kalbermatten, Daniel F, 1969-, et al.
(författare)
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Fibrin matrix for suspension of regenerative cells in an artificial nerve conduit
- 2008
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Ingår i: Journal of plastic, reconstructive and aesthetic surgery. - : Elsevier BV. - 1878-0539 .- 1748-6815. ; 61:6, s. 669-675
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Tidskriftsartikel (refereegranskat)abstract
- Peripheral nerve injury presents with specific problems of neuronal reconstructions, and from a clinical viewpoint a tissue engineering approach would facilitate the process of repair and regeneration. We have previously used artificial nerve conduits made from bioresorbable poly-3-hydroxybutyrate (PHB) in order to refine the ways in which peripheral nerves are repaired and reconnected to the target muscles and skin. The addition of Schwann cells (SC) or differentiated mesenchymal stem cells (dMSC) to the conduits enhances regeneration. In this study, we have used a matrix based on fibrin (Tisseel) to fill optimally the nerve-conduits with cells. In vitro analysis showed that both SC and MSC adhered significantly better to PHB in the presence of fibrin and cells continued to maintain their differentiated state. Cells were more optimally distributed throughout the conduit when seeded in fibrin than by delivery in growth medium alone. Transplantation of the nerve conduits in vivo showed that cells in combination with fibrin matrix significantly increased nerve regeneration distance (using PGP9.5 and S100 distal and proximal immunohistochemistry) when compared with empty PHB conduits. This study shows the beneficial combinatory effect of an optimised matrix, cells and conduit material as a step towards bridging nerve gaps which should ultimately lead to improved functional recovery following nerve injury.
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| 16. |
- Kalbermatten, Daniel F, 1969-, et al.
(författare)
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New fibrin conduit for peripheral nerve repair
- 2009
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Ingår i: Journal of reconstructive microsurgery. - : Georg Thieme Verlag KG. - 0743-684X .- 1098-8947. ; 25:1, s. 27-33
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Tidskriftsartikel (refereegranskat)abstract
- An ideal substitute to treat a nerve gap has not been found. Initially, silicone conduits were employed. Later, conduits were fabricated from collagen or polyesters carbonates. More recently, it has been shown that a bioresorbable material, poly-3-hydroxybutyrate (PHB), can enhance nerve repair. The present investigation shows the use of fibrin as a conduit to guide nerve regeneration and bridge nerve defects. In this study we prepared and investigated a novel nerve conduit made from fibrin glue. Using a rodent sciatic nerve injury model (10-mm gap), we compared the extent of nerve regeneration through the new fibrin conduits versus established PHB conduits. After 2 and 4 weeks, conduits containing proximal and distal stumps were harvested. We evaluated the initial axon and Schwann cell stimulation using immunohistochemistry. The conduits presented full tissue integration and were completely intact. Axons crossed the gap after 1 month. Immunohistochemistry using the axonal marker PGP 9.5 showed a superior nerve regeneration distance in the fibrin conduit compared with PHB (4.1 mm versus 1.9 mm). Schwann cell intrusion (S100 staining) was similarly enhanced in the fibrin conduits, both from the proximal (4.2 mm versus 2.1 mm) and distal ends (3.2 mm versus 1.7 mm). These findings suggest an advantage of the new fibrin conduit for the important initial phase of peripheral nerve regeneration. The use of fibrin glue as a conduit is a step toward a usable graft to bridge peripheral nerve lesions. This might be clinically interesting, given the widespread acceptance of fibrin glue among the surgical community.
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| 17. |
- Khaplanov, Anton, et al.
(författare)
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Compton imager based on a single planar segmented HPGe detector
- 2007
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 580, s. 1075-1078
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Tidskriftsartikel (refereegranskat)abstract
- A collimator-free Compton imaging system has been developed based on a single high-purity germanium detector and used to generate images of radioactive sources emitting gamma rays. The detector has a planar crystal with one pixellated contact with a total of 25 segments. Pulse shape analysis has been applied to achieve a 3D-position sensitivity of the detector. The first imaging results from this detector are presented, based on the reconstruction of events where a gamma ray is fully absorbed after scattering between adjacent segments.
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| 18. |
- Martinez, Juan Pablo, et al.
(författare)
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Assessment of QT-measurement accuracy using the 12-lead electrocardiogram derived from EASI leads
- 2007
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Ingår i: Journal of Electrocardiology. - : Elsevier BV. - 1532-8430 .- 0022-0736. ; 40:2, s. 172-179
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the present study is to assess QT-interval measurements from the EASI 12-lead electrocardiogram (ECG) as compared with the standard 12-lead ECG. The QT interval was automatically determined in simultaneously recorded standard and EASI 12-lead ECGs, using a validated wavelet-based delineator. The agreement between the 2 sets of measurements was quantified both on a lead-by-lead basis and a multilead basis with global definitions of QRS onset and T-wave end. The results show that the agreement between QT-interval measurements from the 2 lead systems is acceptable, with negligible mean differences and with correlation coefficients ranging from 0.91 to 0.98 depending on the lead studied. Although the SD shows a clear dependence on the selected lead (ranging from 9.2 to 26.4 milliseconds), differences are within the accepted tolerances for automatic delineation. In a few patients, large differences were found, mainly because of changes in morphology present in both lead systems. QT intervals measured by the multilead approach were considerably more stable than single-lead measurements and resulted in a much better agreement between the 2 lead systems (correlation coefficient, 0.98; QT difference, 1.1 +/- 9.8 milliseconds). Thus, the EASI 12-lead ECG may be used for reliable QT monitoring when the multilead delineation approach is adopted. (c) 2007 Elsevier Inc. All rights reserved.
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| 19. |
- Naslund, J., et al.
(författare)
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Non-invasive continuous estimation of blood flow changes in human patellar bone
- 2006
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Ingår i: Medical and Biological Engineering and Computing. - : Springer Science and Business Media LLC. - 0140-0118 .- 1741-0444. ; 44:6, s. 501-509
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Tidskriftsartikel (refereegranskat)abstract
- A photoplethysmographic (PPG) technique to assess blood flow in bone tissue has been developed and tested. The signal detected by the PPG consists of a constant-level (DC) component - which is related to the relative vascularization of the tissue - and a pulsatile (AC) component - which is synchronous with the pumping action of the heart. The PPG probe was applied on the skin over the patella. The probe uses near-infrared (804 nm) and green (560 nm) light sources and the AC component of the PPG signals of the two wavelengths was used to monitor pulsatile blood flow in the patellar bone and the overlying skin, respectively. Twenty healthy subjects were studied and arterial occlusion resulted in elimination of PPG signals at both wavelengths, whereas occlusion of skin blood flow by local surface pressure eliminated only the PPG signal at 560 nm. In a parallel study on a physical model with a rigid tube we showed that the AC component of the PPG signal originates from pulsations of blood flow in a rigid structure and not necessarily from volume pulsations. We conclude that pulsatile blood flow in the patellar bone can be assessed with the present PPG technique. © International Federation for Medical and Biological Engineering 2006.
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| 20. |
- Novikova, Liudmila N, et al.
(författare)
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Biodegradable poly-beta-hydroxybutyrate scaffold seeded with Schwann cells to promote spinal cord repair
- 2008
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Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612 .- 1878-5905. ; 29:9, s. 1198-1206
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Tidskriftsartikel (refereegranskat)abstract
- Cavity formation is an important obstacle impeding regeneration after spinal cord injury and bridging strategies are essential to provide physical substrate allowing axons to grow across the lesion site. In this study we evaluated effects of biodegradable tubular conduit made from poly-beta-hydroxybutyrate (PHB) scaffold with predominantly unidirectional fiber orientation and supplemented with cultured adult Schwann cells on axonal regeneration after cervical spinal cord injury in adult rats. After transplantation into the injured spinal cord, plain PHB conduit was well-integrated into posttraumatic cavity and induced modest astroglial reaction. Regenerating axons were found mainly outside the PHB with only single fibers crossing the host-graft interface. No host Schwann cells migrated into the graft. In contrast, when suspension of adult Schwann cells was added to the PHB during transplantation, neurofilament-positive axons filled the conduit and became associated with the implanted cells. Although rubrospinal fibers did not enter the PHB, numerous raphaespinal and CGRP-positive axons were found within the conduit. Modification of PHB surface with fibronectin, laminin or collagen significantly increased Schwann cell attachment and proliferation in vitro. However, transplantation of PHB conduit pre-coated with fibronectin and seeded with Schwann cells did not alter axonal growth response. The results demonstrate that a PHB scaffold promotes attachment, proliferation and survival of adult Schwann cells and supports marked axonal regeneration within the graft.
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