| 1. |
- Brodén, Cyrus, et al.
(författare)
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Accuracy and precision of a CT method for assessing migration in shoulder arthroplasty : an experimental study
- 2019
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Ingår i: Acta Radiologica. - : Sage Publications. - 0284-1851 .- 1600-0455.
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Tidskriftsartikel (refereegranskat)abstract
- Background: Radiostereometric analysis (RSA) is the gold standard to measure early implant migration which is a predictive factor for implant survival. Purpose: To validate an alternative computed tomography (CT) technique to measure implant migration in shoulder arthroplasty. Material and Methods: A cadaver proximal humerus and a scapula, which had tantalum beads incorporated within them, were prepared to accept a short-stemmed humeral component and a two-pegged glenoid component of a commercial total shoulder arthroplasty (TSA) system. A five degree of freedom micrometer and goniometer equipped rig was used to translate and rotate the implant components relative to the respective bone to predetermined positions. Double CT examinations were performed for each position and CT motion analysis software (CTMA) was used to assess these movements. The accuracy and precision of the software was estimated using the rig’s micrometers and goniometers as the gold standard. The technique’s effective dose was also assessed. Results: The accuracy was in the range of 0.07–0.23 mm in translation and 0.22–0.71° in rotation. The precision was in the range of 0.08–0.15 mm in translation and 0.23–0.54° in rotation. The mean effective dose for the CT scans was calculated to be 0.27 mSv. Conclusion: In this experimental setting, accuracy, precision, and effective dose of the CTMA technique were found to be comparable to that of RSA. Therefore, we believe clinical studies are warranted to determine if CTMA is a suitable alternative to traditional RSA for migration measurements in TSA.
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| 2. |
- Brodén, Cyrus, et al.
(författare)
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Low-dose CT-based implant motion analysis is a precise tool for early migration measurements of hip cups : a clinical study of 24 patients
- 2020
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Ingår i: Acta Orthopaedica. - : Informa UK Limited. - 1745-3674 .- 1745-3682. ; 91:3, s. 260-265
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose - Early implant migration is known to be a predictive factor of clinical loosening in total hip arthroplasty (THA). Radiostereometric analysis (RSA) is the gold standard used to measure early migration in patients. However, RSA requires costly, specialized imaging equipment and the image process is complex. We determined the precision of an alternative, commercially available, CT method in 3 ongoing clinical THA studies, comprising 3 different cups.Materials and methods - 24 CT double examinations of 24 hip cups were selected consecutively from 3 ongoing prospective studies: 2 primary THA (1 cemented and 1 uncemented) and 1 THA (cemented) revision study. Precision of the CT-based implant motion analysis (CTMA) system was calculated separately for each study, using both the surface anatomy of the pelvis and metal beads placed in the pelvis.Results - For the CTMA analysis using the surface anatomy of the pelvis, the precision ranged between 0.07 and 0.31 mm in translation and 0.20° and 0.39° for rotation, respectively. For the CTMA analysis using beads the precision ranged between 0.08 and 0.20 mm in translation and between 0.20° and 0.43° for rotations. The radiation dose ranged between 0.2 and 2.3 mSv.Interpretation - CTMA achieved a clinically relevant and consistent precision between the 3 different hip cups studied. The use of different hip cup types, different CT scanners, or registration method (beads or surface anatomy) had no discernible effect on precision. Therefore, CTMA without the use of bone markers could potentially be an alternative to RSA to measure early migration.
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| 3. |
- Engstrand, Per O., 1955-, et al.
(författare)
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Mekmassainitiativet för energieffektivitet, e2mp-i
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Projektet har drivits som ett program för finansiering av forskning som ska utveckla ochdemonstrera tekniker som reducerar elenergiförbrukningen med 50% vid tillverkning avTMP och CTMP med bibehållna slutproduktegenskaper hos tryckpapper och kartong.Programmet är en del av skogsindustrins initiativ att under en tioårsperiod tillsammansmed svenska och norska finansiärer investera minst 200 Mkr för att nå detta radikalaeffektiviseringsmål. Ett uttalat mål för industriinitiativet är också att befästaforskningsnoderna vid FSCN i Sundsvall och PFI i Trondheim.Parallellt med Energimyndighetens finansiering, 30 Mkr, har Norges Forskningsråd satsat25 MNOK (2010‐14) i industriinitiativet, KK‐stiftelsen 36 MSEK (2011‐17) ochMittuniversitetet har finansierat12 MSEK. Industrins totala satsning kommer att överstiga100 MSEK redan vid utgången av 2017.Resultat från benchmarkingstudien BAT2012 av industrins modernaste TMP‐ och CTMPlinjersamt från demonstrationsskaleprojekt visas i rapporten. Projekten baseras delvis pågrundläggande forskningsprojekt genomförda inom FSCN´s KK‐stiftelse‐finansieradeforskningsprofil och projektet ”Filling the Gap” 31676‐, ISSN 1650‐5387 2014:57. Resultaten visar följande reduktionsnivåer; 28% TMP för news (Braviken), 14% TMP för SC(Kvarnsveden) och 21% CTMP för kartong (Skoghall).Utöver demoprojekten finns ytterligare tydliga potentialer beskrivna i övriga delprojekt:Processintensifiering och processmodifiering > 15%Processtabilitet via avancerad processanalys och reglering > 15%Kombinera effektivaste processavsnitt från benchmarking ca 25%Detta gör det troligt att det kommer att gå att i fullskaliga demonstrationsförsök validera50% elenergireduktion inom de tre produktområdena, förutsatt att fortsattforskningsfinansiering finns tillgänglig. Tre av de idéer till avknoppningsprojekt somframkommit under projektets gång har redan erhållit beslut om finansiering frånEnergimyndigheten 2015. Ytterligare projektförslag baserade på den här redovisadeforskningen kommer att ingå i ansökningar under 2016. Utöver energireduktion i själva TMP‐ och CTMP‐processerna har forskare vid FSCN lagt forskningsgrunden för hur manska kunna tillverka mycket starka förpackningsmaterial från dessa massatyper på ettenergieffektivt sätt. Även inom detta område kommer en ansökning omuppskalningsprojekt att skickas in.
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| 4. |
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| 5. |
- Sandberg, Olof H., et al.
(författare)
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Computed tomography-based radiostereometric analysis in orthopedic research: practical guidelines
- 2023
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Ingår i: ACTA ORTHOPAEDICA. - : Medical Journals Sweden. - 1745-3674 .- 1745-3682. ; 94, s. 373-378
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Tidskriftsartikel (refereegranskat)abstract
- - Early implant migration is an indicator of the long-term survival/failure of implants. CT-based radio-stereometric analysis (CT-RSA) is a precise method for mea-suring and visualizing implant migration in vivo using image processing of CT scans. This makes the method widely applicable to orthopedic researcher. Since its development in the early 2000s, CT-RSA has benefited from breakthroughs in CT and computing technol-ogy. These advancements have allowed for the acquisition of images with higher resolution at a much lower radiation dose. As a result, the measurement precision of CT-RSA is now comparable to that of the current gold standard technol-ogy while still compatible with most ethical considerations regarding radiation exposure. In this review we present bests practices for the successful execution of CT-RSA research projects. These practices are based on experience from projects on the hip, knee, shoulder, lower back, cervical spine, foot, pelvis, and wrist.
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| 6. |
- Abtahi, Jahan, et al.
(författare)
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Bisphosphonate-induced osteonecrosis of the jaw in a rat model arises first after the bone has become exposed. No primary necrosis in unexposed bone
- 2012
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Ingår i: Journal of Oral Pathology & Medicine. - : John Wiley and Sons. - 0904-2512 .- 1600-0714. ; 41:6, s. 494-499
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Tidskriftsartikel (refereegranskat)abstract
- J Oral Pathol Med (2012) 41: 494499 Background: Bisphosphonate-related osteonecrosis of the jaw was first described to start with sterile osteocyte death, similar to osteonecrosis in other parts of the skeleton. The typical chronic osteomyelitis was thought to develop when the dead bone was exposed to the oral cavity. An alternative explanation would be that the chronic osteomyelitis is a result of a bisphosphonate-related inability of infected bony lesions to heal. We tested the hypothesis that primary osteocyte death is not necessary for the development of jaw osteonecrosis. Material and methods: Forty rats were randomly allocated to four groups of 10. All animals underwent unilateral molar extraction and received the following drug treatments: Group I, controls with no drug treatment; Group II, 200 mu g/kg per day alendronate; Groups III and IV, 200 mu g/kg per day alendronate and 1 mg/kg of dexamethasone. All rats were euthanized after 14 days. Presence of osteonecrosis was determined by clinical and histological observations for groups IIII. For group IV, osteocyte viability at the contralateral uninjured site was examined using lactate dehydrogenase histochemistry (LDH). Results: All animals in the alendronate plus dexamethasone groups developed large ONJ-like lesions. Lactate dehydrogenase staining showed viable osteocytes in the contralateral jaw with no tooth extraction. No signs of osteonecosis were seen in the other groups. Conclusion: Bisphosphonates and dexamethasone caused no osteocyte death in uninjured bone, but large ONJ-like lesions after tooth extraction. Osteonecrosis of the jaw appears to arise first after the bone has been exposed. Possibly, bisphosphonates hamper the necessary resorption of bone that has become altered because of infection.
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| 7. |
- Abtahi, Jahan, et al.
(författare)
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Effect of Local vs. Systemic Bisphosphonate Delivery on Dental Implant Fixation in a Model of Osteonecrosis of the Jaw
- 2013
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Ingår i: Journal of Dental Research. - : Sage Publications. - 0022-0345 .- 1544-0591. ; 92:3, s. 279-283
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Tidskriftsartikel (refereegranskat)abstract
- Locally applied bisphosphonates may improve the fixation of metal implants in bone. However, systemic bisphosphonate treatment is associated with a risk of osteonecrosis of the jaw (ONJ). We hypothesized that local delivery of bisphosphonate from the implant surface improves the fixation of dental implants without complications in a setting where systemic treatment induces ONJ. Forty rats were randomly allocated to 4 groups of 10. All groups received a titanium implant inserted in an extraction socket. Group I received the implants only. Group II received dexamethasone (0.5 mg/kg). Group III received dexamethasone as above plus alendronate (200 µg/kg). Group IV received zoledronate-coated implants and dexamethasone as above. The animals were sacrificed 2 weeks after tooth extraction. All 10 animals with systemic alendronate treatment developed large ONJ-like changes, while all with local treatment were completely healed. Implant removal torque was higher for the bisphosphonate-coated implants compared with the other groups (p < 0.03 for each comparison). Micro-computed tomography of the maxilla showed more bone loss in the systemic alendronate group compared with groups receiving local treatment (p = 0.001). Local bisphosphonate treatment appears to improve implant fixation in a setting where systemic treatment caused ONJ.
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| 8. |
- Agholme, Fredrik, et al.
(författare)
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Wnt gene expression during metaphyseal bone healing under different load conditions
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Bone Wnt signalling has been presented as one of the key pathways through which bone responds to mechanical load. This pathway is also active during the healing process after bone trauma. Bone healing can be improved by pharmacological modulation of Wnt signalling. We investigated how the expression of several Wntrelated genes changed due to trauma and unloading in metaphyseal bone. 20 male rats had one hind limb unloaded by intramuscular Botox injections. In half of the animals a hole was drilled bilaterally in the proximal tibia. After 7 days, a cylindrical biopsy was taken from the bone surrounding the hole and at a corresponding site in animals without trauma. The biopsies were analyzed for the mRNA expression of Wnt1, Wnt3a, Wnt4, Wnt5a, Wnt5b, Sost, Dkk1, Dkk2, Sfrp1, Sfrp4, Lrp5, Lrp6, Wisp1, Wif1 and Wnt10b. Trauma led to upregulation of most of the studied genes. This effect was most evident in unloaded bone, where 8 genes were upregulated, among them Wnt receptors, ligands and inhibitors. Unloading increased the expression of Sost in untraumatized bone, but did not significantly influence the other genes.
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| 9. |
- Ah Shenga, Pedro, et al.
(författare)
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Log sawing positioning optimization and log bucking of tropical hardwood species to increase the volume yield
- 2017
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Ingår i: Wood Material Science & Engineering. - : Taylor & Francis. - 1748-0272 .- 1748-0280. ; 12:4, s. 257-262
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Tidskriftsartikel (refereegranskat)abstract
- The sawmill industry is a very important link in the Mozambique forest products value chain, but the industry is characterized by undeveloped processing technology and high-volume export of almost unrefined logs. The low volume yield of sawn timber has been identified as a critical gap in the technological development of the industry. To improve the profitability of the industry, there is thus a need to develop methods and techniques that improve the yield. In this paper, different positioning of logs prior to sawing and the possibility of increasing the volume yield of crooked logs by bucking the logs before sawing have been studied. A computer simulation was used to study the cant-sawing and through-and-through sawing of the logs to determine the volume yield of sawn timber from the jambirre (Millettia stuhlmannii Taub.) and umbila (Pterocarpus angolensis DC.) species. The optimal position, i.e. the position of the log before sawing that gives the highest volume yield of sawn timber for a given sawing pattern when the positioning parameters, offset, skew and rotation, are considered gave a considerable higher volume yield than the horns-down position. By bucking very crooked logs and using the horns-down positioning before sawing, the volume yield can be of the same magnitude as that obtained by optimal positioning on full-length (un-bucked) logs. The bucking reduces the crook of the logs and hence increases the volume yield of sawn timber.
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| 10. |
- Ah Shenga, Pedro
(författare)
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SAWING STRATEGIES FOR TROPICAL HARDWOOD SPECIES : Simulation studies based on industrial conditions of Mozambique
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The harvesting of Mozambique tropical hardwood species is considerable higher than the natural regrowth in the forest and the stock is decreasing drastically. Therefore, it is important to improve the material recovery when the wood is refined (i.e., in sawing and further refinement to products such as joineries, furniture etc.) to reduce the waste and to re-utilize efficiently the by-products to increase the added value. The wood processing industry is an important means to boost the industries in the rural areas and also to generate incomes for the local communities by creating jobs and business opportunities.The majority of the logging that can be used for sawmilling in Mozambique is exported as roundwood due to the inability of companies to meet the product standards set for export and to generate profit. The lack of capabilities of the local sawmills to generate profit, also foments the illegal logging because of the higher price of roundwood for export which contributes to increase the number of unlicensed individuals in harvesting. This threatens the law enforcement and thus the degradation of the local wood industry. An alternative to increase the profit and empower the local community could be to export more refined wood products such as sawn timber, parquet, and veneer instead of the roundwood.The objective of the work was to investigate alternative sawing strategies of tropical hardwood species that could increase the profitability of the Mozambique wood industry in general and at sawmill in particular. The subject was approached using a database of virtual logs and together with a sawing simulator. The thesis has two main focus areas: (1) creating the log database with the corresponding algorithms for sawing simulation, and (2) investigations of alternative sawing strategies.The first focus was to build the database of surface-scanned logs and develop the algorithm for the saw simulation. The results are a database of 15 logs models describing the logs outer shape in which 10 jambirre (Millettia stuhlmannii Taub.) and 5 umbila (Pterocarpus angolensis DC.), and the algorithm for the sawing simulation. The algorithm use “brute force” i.e., determines all volume yields of sawn timber from the combination of all settings of log-positioning parameters (offset, skew and rotation) and selects the maximum value of volume yield. From simulation, using three sawing patterns (cant-sawing, through-and-through sawing and square-sawing) combined with two positioning parameters (offset and rotation) it was found that the sawing pattern has great impact on volume yield and that the square-sawing gave higher yield followed by through-and-through sawing pattern.The second focus was on alternative sawing strategies; having in mind that the optimal volume yield is achieved by aid of computerized production systems and that these resources are not yet in use in Mozambique. Hence, the objective was to find the positioning parameters that can be set manually and improve the volume yield. The result have shown that the rotation is the most affecting parameter followed by offset and skew, and that the volume yield can decrease by between 7.7% and 12.5% from the optimal positioning when the logs are manually positioned with the knowledge about the optimal log position. In another study, using crook-up or horns-down positioning as alternative to the optimal positioning, the volume yield decreases by between 10% and 13% from the optimal positioning. By using bucked logs , the optimal volume yield increased by between 8% and 13% in relation to full lengths logs, and the volume yield of bucked logs when using crook up positioning decreases 2% in relation to optimal positioning of full length logs.It is concluded that there is an unexploited value potential in the wood chain which can be reached using alternative positioning and modern measurement techniques and that the grading of wood will facilitate and improve the sawing process.
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| 11. |
- Ah Shenga, Pedro, et al.
(författare)
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Simulation of Tropical Hardwood Processing – Sawing Methods, Log Positioning, and Outer Shape
- 2015
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Ingår i: BioResources. - : BioResources. - 1930-2126. ; 10:4, s. 7640-7652
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Tidskriftsartikel (refereegranskat)abstract
- To increase understanding of breakdown strategies for Mozambican timber, simulations were carried out using different sawing patterns that can be alternatives to the low degree of refinement performed for export today. For the simulations, 3D models of 10 Jambirre and 5 Umbila logs were used. The log shape was described as a point cloud and was acquired by 3D-laser scanning of real logs. Three sawing patterns (cant-sawing, through-and-through sawing, and square-sawing) were studied in combination with the log positioning variables skew and rotation. The results showed that both positioning and choice of sawing pattern had a great influence on the volume yield. The results also showed that the log grade had an impact on the sawing pattern that should be used for a high volume yield. The volume yield could be increased by 3 percentage points by choosing alternative sawing patterns for fairly straight logs and by 6 percentage points for crooked logs, compared to the worst choice of sawing pattern.
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| 12. |
- Ah Shenga, Pedro, et al.
(författare)
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The Effect of Log Position Accuracy on the Volume Yield in Sawmilling of Tropical Hardwood
- 2016
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Ingår i: BioResources. - : BioResources. - 1930-2126. ; 11:4, s. 9560-9571
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the effect of the positioning of the log before sawing on the volume yield of sawn timber from tropical hardwood species. Three positioning parameters were studied, the offset, skew, and rotation, combined with two sawing patterns of cant-sawing and through-and-through sawing. A database consisting of two tropical hardwood species with very different outer shapes, jambirre (Millettia stuhllmannii Taub.) and umbila (Pterocarpus angolensis DC.), was used to simulate the sawing process. The result of the simulation revealed that, according to the combined effect of offset, skew, and rotation positioning, the positioning of the log before sawing is extremely important to achieve a high volume yield of sawn timber. The positioning parameter that has the highest effect on the volume yield is the rotation, and the variation in the volume yield associated with a deviation in the positioning can reduce the volume yield of sawn timber by between 7.7% and 12.5%.
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| 13. |
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| 14. |
- Andersson, Therese, et al.
(författare)
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Low-level mechanical stimulation is sufficient to improve tendon healing in rats
- 2012
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Ingår i: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 113:9, s. 1398-1402
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Tidskriftsartikel (refereegranskat)abstract
- Treatment of tendon injuries often involves immobilization. However, immobilization might not prevent mild involuntary isometric muscle contraction. The effect of weak forces on tendon healing is therefore of clinical interest. Studies of tendon healing with various methods for load reduction in rat Achilles tendon models show a consistent reduction in tendon strength by at least half, compared with voluntary cage activity. Unloading was not complete in any of these models, and the healing tendon was therefore still exposed to mild mechanical stimulation. By reducing the forces acting on the tendon even further, we now studied the effects of this mild stimulation. Rat Achilles tendons were transected and allowed to heal spontaneously under four different loading conditions: 1) normal cage activity; 2) calf muscle paralysis induced by botulinum toxin A (Botox); 3) tail suspension; 4) Botox and tail suspension, combined, to eliminate even mild stimulation. Healing was evaluated by mechanical testing after 8 days. Botox alone and suspension alone both reduced tendon callus size (transverse area), thereby impairing its strength compared with normal cage activity. The combination of Botox and suspension did not further reduce tendon callus size but drastically impaired the material properties of the tendon callus compared with each treatment alone. The peak force was only a fifth of that in the normal cage activity group. The results indicate that also the mild loading that occurs with either Botox or suspension alone stimulates tendon healing. This stimulation appears to affect mainly tissue quality, whereas stronger stimulation also increases callus size.
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| 15. |
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| 16. |
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| 17. |
- Aspenberg, Per, et al.
(författare)
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Distal radial fractures heal by direct woven bone formation
- 2013
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Ingår i: Acta Orthopaedica. - : Informa Healthcare. - 1745-3674 .- 1745-3682. ; 84:3, s. 297-300
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Tidskriftsartikel (refereegranskat)abstract
- Background Descriptions of fracture healing almost exclusively deal with shaft fractures and they often emphasize endochondral bone formation. In reality, most fractures occur in metaphyseal cancellous bone. Apart from a study of vertebral fractures, we have not found any histological description of cancellous bone healing in humans.Patients and methods We studied histological biopsies from the central part of 12 distal radial fractures obtained during surgery 6–28 days after the injury, using routine hematoxylin and eosin staining.Results New bone formation was seen in 6 cases. It was always in the form of fetal-like, disorganized woven bone. It seldom had contact with old trabeculae and appeared to have formed directly in the marrow. Cartilage was scarce or absent. The samples without bone formation showed only necrosis, scar, or old cancellous bone.Interpretation The histology suggests that cells in the midst of the marrow respond to the trauma by direct formation of bone, independently of trabecular surfaces.
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| 18. |
- Bernhardsson, Magnus, et al.
(författare)
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Anti-RANKL treatment improves screw fixation in cancellous bone in rats
- 2015
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Ingår i: Injury. - : Elsevier. - 0020-1383 .- 1879-0267. ; 46:6, s. 990-995
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Tidskriftsartikel (refereegranskat)abstract
- Bisphosphonates improve implant fixation in randomised clinical trials of knee prostheses, hip prostheses and dental implants. However, a limited amount of bone resorption is required for bisphosphonates to exert an effect. Anti-RANKL treatment does not have this limitation, and we therefore tested whether if they might be more effective for improvement of implant fixation. This is of interest, as anti-RANKL treatment with denosumab is now in common clinical use. Male SD rats received a stain-less steel screw in the right proximal tibia and a drill hole in the left (n = 42). They were randomised to subcutaneous injections of either alendronate (20 mu g/kg/day), alendronate (200 mu g/kg/day), osteoprotegerin with an Fc tag (OPG-Fc; 8 mg/kg, twice weekly), or saline control. After 4 weeks, the fixation of the steel screw was measured by pull-out test. The tibia with the drill hole was evaluated with mu CT. OPG-Fc increased the pull-out force compared to saline controls by 153% (p less than 0.001). There was no significant difference between OPG-Fc and the alendronate groups. OPG-Fc increased the bone density (BV/TV) in the previous drill hole compared to controls 7-fold (p less than 0.001). This increase was higher than with any alendronate dose (p less than 0.001). OPG-Fc increased the bone density of the L5 vertebral body, but there was no significant difference between OPG-Fc and alendronate. Our results suggest that screw fixation in cancellous bone can be dramatically improved by an antiRANKL agent. The effect was comparable to very high bisphosphonate doses. Screw insertion in cancellous bone elicits a metaphyseal fracture healing response, and our findings might be relevant not only for implant fixation, but also for fracture healing in cancellous bone.
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| 19. |
- Bernhardsson, Magnus, et al.
(författare)
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Experimental models for cancellous bone healing in the rat Comparison of drill holes and implanted screws
- 2015
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Ingår i: Acta Orthopaedica. - : TAYLOR & FRANCIS LTD. - 1745-3674 .- 1745-3682. ; 86:6, s. 745-750
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose - Cancellous bone appears to heal by mechanisms different from shaft fracture healing. There is a paucity of animal models for fractures in cancellous bone, especially with mechanical evaluation. One proposed model consists of a screw in the proximal tibia of rodents, evaluated by pull-out testing. We evaluated this model in rats by comparing it to the healing of empty drill holes, in order to explain its relevance for fracture healing in cancellous bone. To determine the sensitivity to external influences, we also compared the response to drugs that influence bone healing. Methods - Mechanical fixation of the screws was measured by pull-out test and related to the density of the new bone formed around similar, but radiolucent, PMMA screws. The pull-out force was also related to the bone density in drill holes at various time points, as measured by microCT. Results - The initial bone formation was similar in drill holes and around the screw, and appeared to be reflected by the pull-out force. Both models responded similarly to alendronate or teriparatide (PTH). Later, the models became different as the bone that initially filled the drill hole was resorbed to restore the bone marrow cavity, whereas on the implant surface a thin layer of bone remained, making it change gradually from a trauma-related model to an implant fixation model. Interpretation - The similar initial bone formation in the different models suggests that pull-out testing in the screw model is relevant for assessment of metaphyseal bone healing. The subsequent remodeling would not be of clinical relevance in either model.
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| 20. |
- Bernhardsson, Magnus, et al.
(författare)
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Marrow compartment contribution to cortical defect healing
- 2018
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Ingår i: Acta Orthopaedica. - : TAYLOR & FRANCIS LTD. - 1745-3674 .- 1745-3682. ; 89:1, s. 119-123
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose - Healing of shaft fractures is commonly described as regards external callus. We wanted to clarify the role of the bone marrow compartment in the healing of stable shaft fractures. Patients and methods - A longitudinal furrow was milled along the longitudinal axis of the femoral shaft in mice. The exposed bone marrow under the furrow was scooped out. The mice were then randomized to no further treatment, or to receiving 2 silicone plugs in the medullary canal distal and proximal to the defect. The plugs isolated the remaining marrow from contact with the defect. Results were studied with histology and flow cytometry. Results - Without silicone plugs, the marrow defect was filled with new bone marrow-like tissue by day 5, and new bone was seen already on day 10. The new bone was seen only at the level of the cortical injury, where it seemed to form simultaneously in the entire region of the removed cortex. The new bone seemed not to invade the marrow compartment, and there was a sharp edge between new bone and marrow. The regenerated marrow was similar to uninjured marrow, but contained considerably more cells. In the specimens with plugs, the marrow compartment was either filled with loose scar tissue, or empty, and there was only minimal bone formation, mainly located around the edges of the cortical injury. Interpretation - Marrow regeneration in the defect seemed to be a prerequisite for normal cortical healing. Shaft fracture treatment should perhaps pay more attention to the local bone marrow.
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| 21. |
- Bernhardsson, Magnus, et al.
(författare)
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Shining dead bone-cause for cautious interpretation of [F-18]NaF PET scans
- 2018
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Ingår i: Acta Orthopaedica. - : Taylor & Francis. - 1745-3674 .- 1745-3682. ; 89:1, s. 124-127
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose — [18F]Fluoride ([18F]NaF) PET scan is frequently used for estimation of bone healing rate and extent in cases of bone allografting and fracture healing. Some authors claim that [18F]NaF uptake is a measure of osteoblastic activity, calcium metabolism, or bone turnover. Based on the known affinity of fluoride to hydroxyapatite, we challenged this view.Methods — 10 male rats received crushed, frozen allogeneic cortical bone fragments in a pouch in the abdominal wall on the right side, and hydroxyapatite granules on left side. [18F]NaF was injected intravenously after 7 days. 60 minutes later, the rats were killed and [18F]NaF uptake was visualized in a PET/CT scanner. Specimens were retrieved for micro CT and histology.Results — MicroCT and histology showed no signs of new bone at the implant sites. Still, the implants showed a very high [18F]NaF uptake, on a par with the most actively growing and remodeling sites around the knee joint.Interpretation — [18F]NaF binds with high affinity to dead bone and calcium phosphate materials. Hence, an [18F]NaF PET/CT scan does not allow for sound conclusions about new bone ingrowth into bone allograft, healing activity in long bone shaft fractures with necrotic fragments, or remodeling around calcium phosphate coated prostheses
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| 22. |
- Borglund, Erik AM, 1969-, et al.
(författare)
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Business values of electronic records management in SMEs
- 2009
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Ingår i: Proceedings of the 3rd European Conference on Information Management and Evaluation. - UK : Academic Conferences Limited. - 9781906638443 - 9781906638436 ; , s. 51-58
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Electronic records management in Small and Medium Enterprises is a relatively new research area. It is difficult to find much on the SME and electronic record management in academic databases. In public organizations and in large enterprises the management of electronic records is now acknowledged as important for business support. Efficient records management is e.g. necessary for fulfilling requirements found in various legislation such as e.g. the Sarbanes-Oxley Act (SOX). The requirements for documentation in the ISO 9000, and the ISO 14000 series can be fulfilled if standards for records management are used.This paper aims to contribute further knowledge on the quality of records management in SMEs. The following research question has guided this research: How well do SMEs meet minimum ISO 15489 requirements for records management?The research has been carried out within a EU funded research program, where 4 SMEs from both Sweden and Finland have been studied using a qualitative research approach. The data have been collected from four SMEs through interviews. The analytical lens used in this research has been the international standard for Information and Documentation - Record Management: ISO 15489.The results show that electronic records are managed in a rather ad-hoc manner and that management is very dependent upon individuals, many of whom have little, if any, expertise or training in this area and no access to expert advice. One of the identified business values of well-managed electronic records is that the SME gains the opportunity to manage and benefit from their explicit knowledge and experience.This research shows that there are major obstacles to overcome before SMEs are able to fully adopt best practice in electronic records management. Many of these hindrances have their roots in a lack of appropriate strategies for records appraisal and that the SMEs have not followed the steps recommended in the ISO 15489 standard.
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| 23. |
- Chen, Tingsu, et al.
(författare)
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Identification of gliadin-binding peptides by phage display
- 2011
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Ingår i: BMC Biotechnology. - : Springer Science and Business Media LLC. - 1472-6750. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Coeliac disease (CD) is a common and complex disorder of the small intestine caused by intolerance to wheat gluten and related edible cereals like barley and rye. Peptides originating from incomplete gliadin digestion activate the lamina propria infiltrating T cells to release proinflammatory cytokines, which in turn cause profound tissue remodelling of the small intestinal wall. There is no cure for CD except refraining from consuming gluten-containing products. RESULTS: Phage from a random oligomer display library were enriched by repeated pannings against immobilised gliadin proteins. Phage from the final panning round were plated, individual plaques picked, incubated with host bacteria, amplified to a population size of 1011 to 1012 and purified. DNA was isolated from 1000 purified phage populations and the region covering the 36 bp oligonucleotide insert from which the displayed peptides were translated, was sequenced. Altogether more than 150 different peptide-encoding sequences were identified, many of which were repeatedly isolated under various experimental conditions. Amplified phage populations, each expressing a single peptide, were tested first in pools and then one by one for their ability to inhibit binding of human anti-gliadin antibodies in ELISA assays. These experiments showed that several of the different peptide-expressing phage tested inhibited the interaction between gliadin and anti-gliadin antibodies. Finally, four different peptide-encoding sequences were selected for further analysis, and the corresponding 12-mer peptides were synthesised in vitro. By ELISA assays it was demonstrated that several of the peptides inhibited the interaction between gliadin molecules and serum anti-gliadin antibodies. Moreover, ELISA competition experiments as well as dot-blot and western blot revealed that the different peptides interacted with different molecular sites of gliadin. CONCLUSIONS: We believe that several of the isolated and characterised gliadin-binding peptides described here could provide valuable tools for researchers in the field of CD by facilitating studies on localisation and uptake of various gliadin peptides in the small intestine. In future work, the potential of these peptides to detoxify gluten will be investigated.
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| 24. |
- Dahlgren, Sven-Olof, 1956, et al.
(författare)
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Prosodic traits in speech produced by children with autism spectrum disorders – Perceptual and acoustic measurements
- 2018
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Ingår i: Autism & Developmental Language Impairments. - : SAGE Publications. - 2396-9415. ; 3, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Background: Autism spectrum disorder has been associated with atypical voice characteristics and prosody. In the scientific literature, four different aspects of atypical speech production in autism spectrum disorder have been highlighted; voice quality together with the prosodic aspects pitch, duration and intensity. Studies of prosody in autism spectrum disorder have almost exclusively used perceptual methods. Recently, some studies have used acoustic analyses. In these studies, it has been pointed out that the acoustic differences found are not necessarily perceived as atypical by listeners, which is why it is important to let listeners evaluate perceptual correlates to acoustic findings. The aims of this study were to use both perceptual and acoustic analyses to study prosodic production in children with autism spectrum disorder and to examine if voice and speech characteristics could be used as clinical markers for autism spectrum disorder. Method: Eleven children within normal range of intelligence diagnosed with autism spectrum disorder and 11 children with typical development participated. Every child was recorded telling a story elicited with the expression, reception and recall of narrative instrument. Excerpts of one minute were extracted from the audio files creating the material underlying the perceptual ratings and in the acoustic analysis. An evaluation procedure, partly based on a standardized voice evaluation procedure developed for clinical practice in Sweden, was designed for the perceptual judgments and analysis. To capture critical prosodic variables, aspects of prosody based on characteristic features of Swedish prosody, prosodic features known to cause Swedish children with language impairment particular problems and current research of prosodic impairments in children with autism, were used as rating variables. The acoustic analysis was based on the four variables fundamental frequency (fo) average, fo range, fo variation and speech rate, together with the language production-related variable number of words per utterance. Results: In the acoustic analysis, no differences were found with regards to fo-related variables or speech rate. However, the children in the autism spectrum disorder-group produced significantly more words per utterance than the typically developing children. The perceptual analysis showed no differences between the groups. Only three children with autism spectrum disorder were correctly identified as such. The narrative ability of these children, according to scores on the narrative assessment profile, was poorer than that of the other eight children. They were also more atypical in fluency and in speech rate. Given the small sample, the results should be interpreted with caution. Conclusions and implications: The only difference in prosodic production discovered in the acoustic analysis, namely that children with autism spectrum disorder used more words per utterance than the children in the comparison group, was not detected in the perceptual assessment. This implies that it was not perceived as atypical by expert listeners. The results indicate difficulties in using voice and speech characteristics as markers of autism spectrum disorder in clinical settings. The correct identification of some of the children as having autism spectrum disorder or not also indicates that some children with autism spectrum disorder have a prosodic production sufficiently ‘atypical’ in combination with a limited ability to tell stories to be perceived.
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| 25. |
- Dahlgren, Sven-Olof, 1956, et al.
(författare)
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Referential communication in children with autism spectrum disorder
- 2008
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Ingår i: Autism. - : SAGE Publications. - 1362-3613 .- 1461-7005. ; 12:4, s. 335-348
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Tidskriftsartikel (refereegranskat)abstract
- Referential communication was studied in children with autism spectrum disorder (ASD) including children with autism and Asperger syndrome. The aim was to study alternative explanations to the children’s communicative problems in such situations. Factors studied were theory of mind, IQ, verbal ability and memory. The main results demonstrated diminished performance in children with autism spectrum disorder mirroring performance in everyday life in comparison to verbal IQ and mental age matched typically developing children. Among children with autism spectrum disorders, there was a positive relationship between performance in referential communication and theory of mind. Memory capacity proved also to play a role for success in the task.
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