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| 2. |
- Hillier, Ladeana W, et al.
(författare)
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Sequence and comparative analysis of the chicken genome provide unique perspectives on vertebrate evolution
- 2004
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Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 432:7018, s. 695-716
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Tidskriftsartikel (refereegranskat)abstract
- We present here a draft genome sequence of the red jungle fowl, Gallus gallus. Because the chicken is a modern descendant of the dinosaurs and the first non-mammalian amniote to have its genome sequenced, the draft sequence of its genome--composed of approximately one billion base pairs of sequence and an estimated 20,000-23,000 genes--provides a new perspective on vertebrate genome evolution, while also improving the annotation of mammalian genomes. For example, the evolutionary distance between chicken and human provides high specificity in detecting functional elements, both non-coding and coding. Notably, many conserved non-coding sequences are far from genes and cannot be assigned to defined functional classes. In coding regions the evolutionary dynamics of protein domains and orthologous groups illustrate processes that distinguish the lineages leading to birds and mammals. The distinctive properties of avian microchromosomes, together with the inferred patterns of conserved synteny, provide additional insights into vertebrate chromosome architecture.
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| 3. |
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| 4. |
- Cao, Han, et al.
(författare)
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Fabrication of 10 nm enclosed nanofluidic channels
- 2002
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 81:1, s. 174-176
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Tidskriftsartikel (refereegranskat)abstract
- We made uniform arrays of nanometer scale structures using nanoimprint lithography over large areas (100 mm wafers). The nanofluidic channels were further narrowed and sealed by techniques that are based on nonuniform deposition. The resulting sealed channels have a cross section as small as 10 nm by 50 nm, of great importance for confining biological molecules into ultrasmall spaces. These techniques can be valuable fabrication tools for Nanoelectromechanical Systems and Micro/Nano Total Analysis Systems.
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| 5. |
- Kjellson, Fred, et al.
(författare)
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Tensile properties of a bone cement containing non-ionic contrast media
- 2001
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Ingår i: Journal of Materials Science: Materials in Medicine. - 1573-4838. ; 12:10-12, s. 889-894
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Tidskriftsartikel (refereegranskat)abstract
- The addition of contrast media such as BaSO4 or ZrO2 to bone cement has adverse effects in joint replacements, including third body wear and particle-induced bone resorption. Ground PMMA containing particles of the non-ionic water-soluble iodine-based X-ray contrast media, iohexol (IHX) and iodixanol (IDX), has, in bone tissue culture, shown less bone resorption than commercial cements. These water-soluble non-ceramic contrast media may change the mechanical properties of acrylic bone cement. The static mechanical properties of bone cement containing either IHX or IDX have been investigated. There was no significant difference in ultimate stress between Palacos R (with 15.0 wt % of ZrO2) and plain cement with 8.0 wt % of IHX or IDX with mass median diameter (MMD) of 15.0 or 16.0 microm, while strain to failure was higher for the latter (p < 0.02). The larger particles (15.0 or 16.0 microm) gave significantly higher (p < 0.001) ultimate tensile strengths and strains to failure than smaller sizes (2.4 or 3.6 microm). Decreasing the amount of IHX from 10.0 wt % to 6.0 wt % gave a higher ultimate tensile strength (p < 0.001) and strain to failure (p < 0.02). Scanning electron microscopy (SEM) showed the smaller contrast media particles attached to the surface of the polymer beads, which may prevent areas of the acrylate bead surface from participating in the polymerization. In conclusion, the mechanical properties of bone cement were influenced by the size and amount of contrast medium particles. By choosing the appropriate amount and size of particles of water-soluble non-ionic contrast media the mechanical properties of the new radio-opaque bone cement can be optimized, thus reaching and surpassing given regulatory standards.
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| 7. |
- Liu, Jian-Jun, et al.
(författare)
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Hepatic cirrhosis increases sensitivity of kidney to endotoxin in rats
- 2002
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Ingår i: Medical Science Monitor. - 1643-3750. ; 8:2, s. 56-60
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Renal failure in cirrhotic patients is a severe complication and endotoxemia might be involved. We investigated the effect of endotoxin on renal function of cirrhotic rats and the potential protective role of N-acetylcysteine (NAC). MATERIAL/METHODS: Hepatic cirrhosis was generated in a rat model by carbon tetrachloride. Both cirrhotic and normal rats were insulted by endotoxin intravenously, while another cirrhotic group was pre-treated with NAC. Blood urea nitrogen (BUN) and creatinine were assayed eight hours later. The changes in serum tumor necrosis factor-a (TNF-a) were assayed by ELISA. The histological changes in the kidney were observed after hematoxylin and eosin staining. RESULTS: Endotoxin increased the BUN and creatinine levels in both normal and cirrhotic rats, with a much higher elevation in the latter group. TNF-a concentration was also increased by endotoxin; the changes are positively correlated with BUN and creatinine. NAC pretreatment significantly attenuates the effects of endotoxin on BUN, creatinine and TNF-a levels in cirrhotic rats with no improvement in systemic toxicity symptoms. There were no obvious histological changes in the kidney of these animals. CONCLUSIONS: Hepatic cirrhosis increased the sensitivity of renal function to endotoxemia, which may be protected by NAC.
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| 8. |
- Liu, Jian-Jun, et al.
(författare)
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Sulindac induces apoptosis, inhibits proliferation and activates caspase-3 in Hep G2 cells
- 2002
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Ingår i: Anticancer research. - 1791-7530. ; 22:1A, s. 263-266
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Tidskriftsartikel (refereegranskat)abstract
- Background: It has recently been reported that sulindac has an apoptotic effect on KYN-2 cells, an undifferentiated hepatoma cell line. The present work investigates whether sulindac also has an apoptotic effect on well-differentiated hepatoma cells and what its potential mechanism might be. Materials and Methods: Hep G2 cells were treated with sulindac at different concentrations. Apoptosis rate, cell proliferation and 3H-thymidine incorporation were measured. The activities of caspase-3, acid and neutral sphingomyelinase and the changes of sphingomyelin content were also assayed. Results: Sulindac dose-dependently induced apoptosis in Hep G2 cells; both sulindac sulfone and sulfide had similar effects. The apoptosis was accompanied by an increase 3 of caspase-3 activity and a decrease of cell proliferation and H-3-thymidine incorporation. No significant change could be observed for the activity of sphingomyelinase and sphingomyelin content. Conclusion: Sulindac induces apoptosis and inhibits proliferation in Hep G2 cells. The effect may, be mediated by, a pathway related to caspase-3 activation but independent of sphingomyelin metabolism.
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| 9. |
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| 10. |
- Nilsson, M, et al.
(författare)
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Biodegradation and biocompatability of a calcium sulphate-hydroxyapatite bone substitute.
- 2004
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Ingår i: Journal of Bone and Joint Surgery: British Volume. - 2044-5377. ; 86:1, s. 120-125
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Tidskriftsartikel (refereegranskat)abstract
- An injectable material consisting of calcium sulphate mixed with hydroxyapatite was investigated as a possible alternative to autograft in the restoration of bone defects. The material was studied both in vitro in simulated body fluid (SBF) and in vivo when implanted in rat muscles and into the proximal tibiae of rabbits. Variation in the strength and weight of the material during ageing in SBF was measured. Tissue response, material resorption and bone ingrowth were studied in the animal models. A good tissue response was observed in both the rat muscles and rabbit tibiae without inflammatory reactions or the presence of fibrous tissue. Ageing in SBF showed that during the first week carbonated hydroxyapatite precipitated on the surfaces of the material and this may enhance bone ingrowth.
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| 11. |
- Nilsson, Malin K, et al.
(författare)
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Factors influencing the compressive strength of an injectable calcium sulfate-hydroxyapatite cement.
- 2003
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Ingår i: Journal of Materials Science: Materials in Medicine. - 1573-4838. ; 14:5, s. 399-404
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Tidskriftsartikel (refereegranskat)abstract
- A biphasic injectable bone substitute, suitable for filling bone defects, that sets in the body, based on calcium sulfate and hydroxyapatite (HA), is presented. For applications in bone defects the compressive strength is important to assure support of the defect site during loading when the patient is weight bearing. To control the strength, the influence of four different factors; the liquid-to-powder (L/P) ratio, the HA particle morphology, the HA content and the amount of accelerator, were investigated. alpha-Calcium sulfate hemihydrate (CSH) and four different HA powders (three sintered and one spray-dried) were used. All differed in size and morphology. CSH and each HA powder were mixed together with distilled water to form the bone substitute. An accelerator, in form of calcium sulfate dihydrate, was added to the powder phase to obtain an adequate setting time. Cylindrical specimens were compression tested. A lower L/P-ratio gave stronger cement, but was more difficult to inject. The shape and the morphology of the HA particles influenced the strength, and reducing the amount of HA increased the strength. The amount of accelerator (calcium sulfate dihydrate) had no influence. (C) 2003 Kluwer Academic Publishers.
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| 12. |
- Tägil, Magnus, et al.
(författare)
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No augmentation of morselized and impacted bone graft by OP-1 in a weight-bearing model.
- 2003
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Ingår i: Acta Orthopaedica Scandinavica. - : Medical Journals Sweden AB. - 0001-6470. ; 74:6, s. 742-748
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Impacted morselized bone allograft is thought to be remodeled to a great extent. We have previously shown that load-bearing increases the remodeling of impacted morselized bone allografts in a rabbit knee prosthesis model. Bone Morphogenic Proteins (BMPs) also stimulate bone formation and bone allograft remodeling. In this study, our aim was to determine whether it was possible to increase further the remodeling of impacted morselized bone allografts by combining load-bearing with a BMP. Experiment: A solution of Osteogenic Protein-1 (OP-1, also called BMP-7) was added to freeze-dried bone allograft chips before impaction grafting in our rabbit knee prosthesis model. 23 skeletally mature rabbits received an uncemented tibial knee prosthetic component inserted into a bed of impacted morselized bone allograft. 12 rabbits were given OP-1-treated allograft (50 µg OP-1 per gram allograft), and 11 rabbits vehicle-treated allograft. Each rabbit received mean 0.53 g graft. The rabbits were killed after 3 or 6 weeks and the grafted region was examined by histomorphometric assessment of the volume fraction of newly formed bone and remaining graft. Results and interpretation: We found that OP-1 did not increase the bone density (graft plus new bone) to any substantial extent. However, we can not exclude that this might be due to a carrier problem, since the OP-1 was added as a solution directly to the dry graft.
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| 13. |
- Wang, Jian-Sheng, et al.
(författare)
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Bone integration of an injectable calcium phosphate based bone substitute
- 2004
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Ingår i: Transactions - 7th World Biomaterials Congress. - 1877040193 ; , s. 276-276
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Konferensbidrag (refereegranskat)abstract
- The bone formation and bone integration in calcium phosphate (CaP) and CaP with 20% calcium sulfate (CaS) were investigated. In the study, six adult, loop-eared rabbits were used and bone harvest chambers were implanted bilaterally in the proximal tibiae. It was found that the front of bone formation follows closely the front of material resorption without interposition of fibrous tissue. The results implied that a mixture of CaP and CaS can be introduced as an injectable bone graft substitute for filling bone defects.
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| 14. |
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| 15. |
- Wang, Jian-Sheng, et al.
(författare)
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Load-bearing increases new bone formation in impacted and morselized allografts
- 2000
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Ingår i: Clinical Orthopaedics and Related Research. - 0009-921X. ; :378, s. 274-281
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Tidskriftsartikel (refereegranskat)abstract
- The effects of mechanical loading on the incorporation of morselized impacted grafts were addressed in this study. Twelve skeletally mature rabbits were surgically treated. Six rabbits received a proximal tibial joint replacement with a tibial tray and a load-bearing 25-mm long stem. The tibia was packed with fresh frozen, morselized, cancellous rabbit bone. No cement was used. In six other rabbits only the stem was inserted, without a tibial tray, leaving the stem and the likewise impacted bone graft mechanically unloaded. The rabbits were euthanized after 6 weeks, and the tibias were sectioned and analyzed by histomorphometric examination. In the loaded specimens the graft was resorbed and replaced by new bone (30% of area of interest) to a larger extent than in the unloaded specimens. Mechanical loading of an impacted, morselized graft surrounding a conical uncemented stem, increased the amount of new bone that replaced the graft. The ability of morselized impacted grafts to allow mechanical stimulation of ingrown tissue appears to be a principal cause for the success of this grafting procedure.
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| 16. |
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