| 1. |
- Aberg, Jonas, et al.
(författare)
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In vivo evaluation of an injectable premixed radiopaque calcium phosphate cement.
- 2011
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Ingår i: International journal of biomaterials. - : Hindawi Limited. - 1687-8795 .- 1687-8787. ; 2011
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Tidskriftsartikel (refereegranskat)abstract
- In this work a radiopaque premixed calcium phosphate cement (pCPC) has been developed and evaluated in vivo. Radiopacity was obtained by adding 0-40 % zirconia to the cement paste. The effects of zirconia on setting time, strength and radiopacity were evaluated. In the in vivo study a 2 by 3.5mm cylindrical defect in a rat vertebrae was filled with either the pCPC, PMMA or bone chips. Nano-SPECT CT analysis was used to monitor osteoblast activity during bone regeneration. The study showed that by adding zirconia to the cement the setting time becomes longer and the compressive strength is reduced. All materials evaluated in the in vivo study filled the bone defect and there was a strong osteoblast activity at the injury site. In spite of the osteoblast activity, PMMA blocked bone healing and the bone chips group showed minimal new bone formation. At 12 weeks the pCPC was partially resorbed and replaced by new bone with good bone ingrowth. The radiopaque pCPC may be considered to be used for minimal invasive treatment of vertebral fractures since it has good handling, radiopacity and allows healing of cancellous bone in parallel with the resorption of the cement.
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| 2. |
- Alenius Dahlqvist, Jenny, et al.
(författare)
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Heart rate variability in children with fontan circulation : lateral tunnel and extracardiac conduit
- 2012
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Ingår i: Pediatric Cardiology. - New York : Springer-Verlag New York. - 0172-0643 .- 1432-1971. ; 33:2, s. 307-315
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Tidskriftsartikel (refereegranskat)abstract
- The technique in Fontan surgery has developed from the lateral tunnel (LT) toward the extracardiac conduit (EC) used to reduce long-term complications such as atrial arrhythmia and sinus node dysfunction. Heart rate variability (HRV) examines cardiac nervous activity controlling the sinus node. This study aimed to investigate HRV in a cohort of children with univentricular hearts, focusing on the relation between HRV and surgical procedure. For 112 children with Fontan circulation, HRV was analyzed using power spectral analysis. Spectral power was determined in three regions: very-low-frequency (VLF), low-frequency (LF), and high-frequency (HF) regions. Patients were compared with 66 healthy controls subject. Patients with LT were compared with patients who had EC. The children with Fontan circulation showed a significantly reduced HRV including total power (P < 0.0001), VLF (P < 0.0001), LF (P < 0.0001), and HF (P = 0.001) compared with the control subjects. The LT and EC patients did not differ significantly. Reduced HRV was found in both the LT and EC patients. In terms of HRV reduction, EC was not superior to LT.
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| 3. |
- Grandfield, Kathryn, 1986-, et al.
(författare)
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Ultrastructural characterisation of the hydroxyapatite–coated pedicle screw and human bone interface
- 2012
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Ingår i: International Journal of Nano and Biomaterials. - 1752-8933 .- 1752-8941. ; 4:1, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- The early fixation of pedicle screws is crucial for improving spinal stabilisation. Firm and immediate fixation between pedicle screws and bone prevents aseptic loosening and implant failure. Coating with hydroxyapatite is a possible method to improve the fixation of metallic implants in bone. In this study, scanning transmission electron microscopy (STEM) has been used to investigate the ultrastructure of the plasma–sprayed hydroxyapatite coating and human bone interface in detail. Focused ion beam sample preparation also enabled the investigation of the bone–lacunae interface. An intimate contact and elemental analysis between bone and HA coatings suggests bioactive fixation. Therefore, coating with hydroxyapatite leads to enhanced biocompatibility at the ultrastructural level and may lead to improved early and long–term fixation of pedicle screws.
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| 4. |
- Jensen, Per, 1956-, et al.
(författare)
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Feather pecking in chickens is genetically related to behavioural and developmental traits.
- 2005
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Ingår i: Physiology & behavior. - : Elsevier BV. - 0031-9384 .- 1873-507X. ; 86:1-2, s. 52-60
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Tidskriftsartikel (refereegranskat)abstract
- Feather pecking (FP) is a detrimental behaviour in chickens, which is performed by only some individuals in a flock. FP was studied in 54 red junglefowl (ancestor of domestic chickens), 36 White Leghorn laying hens, and 762 birds from an F(2)-intercross between these two lines. From all F(2)-birds, growth and feed consumption were measured. Age at sexual maturity and egg production in females, and corticosterone levels in males were also measured. From 333 F(2)-birds of both sexes, and 20 parental birds, body composition with respect to bone mineral content, muscle and fat was obtained by post-mortem examinations using Dual X-Ray Absorptiometry (DXA). In femurs of the same birds, the bone density and structure were analysed using DXA and Peripheral Quantitative Computerized Tomography (pQCT), and a biomechanical analysis of bone strength was performed. Furthermore, plumage condition was determined in all birds as a measure of being exposed to feather pecking. Using 105 DNA-markers in all F(2)-birds, a genome-wide scan for Quantitative Trait Loci (QTL), associated with the behaviour in the F(2)-generation was performed. FP was at least as frequent in the red junglefowl as in the White Leghorn strain studied here, and significantly more common among females both in the parental strains and in the F(2)-generation. In the F(2)-birds, FP was phenotypically linked to early sexual maturation, fast growth, weak bones, and, in males, also high fat accumulation, indicating that feather peckers have a different resource allocation pattern. Behaviourally, F(2) feather peckers were more active in an open field test, in a novel food/novel object test, and in a restraint test, indicating that feather pecking might be genetically linked to a proactive coping strategy. Only one suggestive QTL with a low explanatory value was found on chromosome 3, showing that many genes, each with a small effect, are probably involved in the causation of feather pecking. There were significant effects of sire and dam on the risk of being a victim of feather pecking, and victims grew faster pre- and post-hatching, had lower corticosterone levels and were less active in a restraint test. Hence, a wide array of behavioural and developmental traits were genetically linked to FP.
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| 5. |
- Larsson, Sune, et al.
(författare)
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Injectable calcium phosphate cement for augmentation around cancellous bone screws : In vivo biomechanical studies
- 2012
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Ingår i: Journal of Biomechanics. - : Elsevier BV. - 0021-9290 .- 1873-2380. ; 45:7, s. 1156-1160
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Tidskriftsartikel (refereegranskat)abstract
- In lower cancellous apparent bone density, it can be difficult to achieve adequate screw fixation and hence stable fracture fixation. Different strategies have been proposed, one of them is through augmentation using calcium phosphate cement in the region at or close to the screw thread itself. To support the hypothesis of an improved screw fixation technique by augmentation of the bone surrounding the implanted screw, in vivo biomechanical and densitometric studies are performed on rabbit specimen where normal and simulated weak bone quality are considered. In particular, the evolution of screw stability till 12 weeks following the implantation is quantified. A statistical significance in the pull out force for augmented versus non-augmented screws was found for the shorter time periods tested of <= 5 days whilst the pull out force was found to increase with time for both augmented and non-augmented screws during the 12 week course of the study. The results of the study demonstrate that the use of an injectable calcium phosphate cement which sets in vivo can significantly improve screw pull out strength at and after implantation for normal and simulated weak bone quality.
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| 6. |
- Olofsson, Christina, et al.
(författare)
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A multicenter clinical study of the safety and activity of maleimide-polyethylene glycol-modified Hemoglobin (Hemospan) in patients undergoing major orthopedic surgery.
- 2006
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Ingår i: Anesthesiology. - : Ovid Technologies (Wolters Kluwer Health). - 0003-3022 .- 1528-1175. ; 105:6, s. 1153-63
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Hemospan (Sangart Inc., San Diego, CA), a polyethylene glycol-modified hemoglobin with unique oxygen transport properties, has successfully completed a phase I trial in healthy volunteers. Because adverse events are expected to increase with age, the authors conducted a phase II safety study of Hemospan in elderly patients undergoing elective hip arthroplasty during spinal anesthesia. METHODS: Ninety male and female patients, American Society of Anesthesiologists physical status I-III, aged 50-89 yr, in six Swedish academic hospitals were randomly assigned to receive either 250 or 500 ml Hemospan or Ringer's acetate (30 patients/group) before induction of spinal anesthesia. Safety assessment included vital signs and Holter monitoring from infusion to 24 h, evaluation of laboratory values, and fluid balance. The hypothesis to be tested was that the incidence of adverse events would be no more frequent in patients who received Hemospan compared with standard of care (Ringer's acetate). RESULTS: Three serious adverse events were noted, none of which was deemed related to study treatment. Liver enzymes, amylase, and lipase increased transiently in patients in all three groups. There were no significant differences in electrocardiogram or Holter parameters, but there was a suggestion of more bradycardic events in the treated groups. Hypotension was less frequent in the treated patients compared with controls. CONCLUSIONS: In comparison with Ringer's acetate, Hemospan mildly elevates hepatic enzymes and lipase and is associated with less hypotension and more bradycardic events. The absence of a high frequency of serious adverse events suggests that further clinical trials should be undertaken.
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| 7. |
- Rubin, Carl-Johan, et al.
(författare)
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Quantitative trait loci for BMD and bone strength in an intercross between domestic and wildtype chickens.
- 2007
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Ingår i: Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research. - : Wiley. - 0884-0431. ; 22:3, s. 375-84
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Tidskriftsartikel (refereegranskat)abstract
- With chicken used as a model species, we used QTL analysis to examine the genetic contribution to bone traits. We report the identification of four QTLs for femoral traits: one for bone strength, one for endosteal circumference, and two affecting mineral density of noncortical bone. INTRODUCTION: BMD is a highly heritable phenotype, governed by elements at numerous loci. In studies examining the genetic contribution to bone traits, many loci have been identified in humans and in other species. The goal of this study was to identify quantitative trait loci (QTLs) controlling BMD and bone strength in an intercross between wildtype and domestic chickens. MATERIALS AND METHODS: A set of 164 markers, covering 30 chromosomes (chr.), were used to genotype 337 F2-individuals from an intercross of domesticated white Leghorn and wildtype red junglefowl chicken. DXA and pQCT were used to measure BMD and bone structure. Three-point bending tests and torsional strength tests were performed to determine the biomechanical strength of the bone. QTLs were mapped using forward selection for loci with significant marginal effects. RESULTS: Four QTLs for femoral bone traits were identified in QTL analysis with body weight included as a covariate. A QTL on chr. 1 affected female noncortical BMD (LOD 4.6) and is syntenic to human 12q21-12q23. Also located on chr. 1, a locus with synteny to human 12q13-14 affected endosteal circumference (LOD 4.6). On chr. 2, a QTL corresponding to human 5p13-p15, 7p12, 18q12, 18q21, and 9q22-9q31 affected BMD in females; noncortical (LOD 4.0) and metaphyseal (LOD 7.0) BMD by pQCT and BMD by DXA (LOD 5.9). A QTL located on chr. 20 (LOD 5.2) affected bone biomechanical strength and had sex-dependent effects. In addition to the significant QTLs, 10 further loci with suggestive linkage to bone traits were identified. CONCLUSIONS: Four QTLs were identified: two for noncortical BMD, one for endosteal circumference, and one affecting bone biomechanical strength. The future identification of genes responsible for these QTLs will increase the understanding of vertebrate skeletal biology.
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| 8. |
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| 9. |
- Silfverswärd, Carl-Johan, et al.
(författare)
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Bone formation in interleukin-4 and interleukin-13 depleted mice.
- 2008
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Ingår i: Acta orthopaedica. - : Medical Journals Sweden AB. - 1745-3682 .- 1745-3674. ; 79:3, s. 410-20
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: Cytokines play an important role in the complex process of bone formation. We have previously found an altered skeletal phenotype with reduction of cortical bone mass in mice depleted of the 2 cytokines interleukin-4 (IL-4) and interleukin-13 (IL 13). The present study was performed to investigate a potential role of IL-4 and IL-13 in fracture healing and bone induction by demineralized xenogenic bone matrix (DXBM). METHODS: Callus formation in IL-4-(/)-IL-13-(/)- (IL-4/13 knockout) and wild-type (WT) male mice was compared using a standardized fracture model. The capacity of IL-4(-/-)IL-13(-/-) and WT male and female mice to form heterotopic bone was compared using intramuscular implants of DXBM. Bone formation and mechanical properties were evaluated by pQCT, ash weight, 3-point bending, radiology, and immunohistology. RESULTS: In the fracture investigation substantial amounts of new bone formation by 5 weeks were found, but no differences in radiographical healing, callus volume, BMD, BMC, or mechanical properties were detected between IL-4(-/-)IL-13(-/-) and WT mice. In the DXBM investigation radiographic analysis confirmed mineralization of implants in both groups, but no difference in the amount of mineral deposition (net bone formation) between IL-4(-/-)IL-13(-/-) and WT mice was found. Immunohistology showed inhibition of autonomic nerves in the capsule of the IL-4(-/-)IL-13(-/-) group along with a lack of vascularization within the implants. INTERPRETATION: Depletion of IL-4 and IL-13 does not cause any major alteration in fracture healing or heterotopic bone formation in mice. The pattern of autonomous nerve expression and expression of markers of neovascularization is, however, altered to some extent by the absence of IL-4 and IL-13.
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| 10. |
- Silfverswärd, Carl-Johan, et al.
(författare)
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Reduced cortical bone mass in mice with inactivation of interleukin-4 and interleukin-13.
- 2007
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Ingår i: Journal of orthopaedic research : official publication of the Orthopaedic Research Society. - : Wiley. - 0736-0266 .- 1554-527X. ; 25:6, s. 725-31
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to study the in vivo role of IL-4 and IL-13 on bone metabolism. The skeletal phenotypes of male and female IL-13(-/-) (n = 7+7), IL-4(-/-)IL-13(-/-) (n = 7+7), and WT (n = 7+7) mice were compared. Analysis was made at 6 weeks of age (juvenile) by pQCT, and at 20 weeks of age (adult) by pQCT, biomechanical testing, and by S-IGF-1 and S-Osteocalcin measurements. The skeletal phenotype was affected only in adult male IL-4(-/-)IL-13(-/-) mice. These animals displayed a reduction in cortical bone mineral content (BMC) of both the tibia and the femur, as measured by mid-diaphyseal pQCT scans, compared with WT mice (tibia -8.2%; femur -8.5%; p < 0.01). This reduction in cortical BMC was due to a decreased cross-sectional area as a result of a reduced cortical thickness. The mechanical strength of the cortical bone, tested by three-point-bending at the mid-diaphyseal region of the femurs, demonstrated a significant reduction of displacement at failure (-11.4%), maximal load at failure (-10.6%), and total energy until failure (-29.4%). S-IGF-1 and S-Osteocalcin levels as well as trabecular bone mineral density (tvBMD) were unaffected in adult male IL-4(-/-)IL-13(-/-) mice. IL-4(-/-)IL-13(-/-) male mice show adult onset reduction of cortical bone mass and strength, indicating that the two anti-inflammatory Th(2) cytokines IL-4 and IL-13 are involved in the regulation of bone remodeling.
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