| 1. |
- Martinez-Sanz, Elena, et al.
(författare)
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Bone reservoir : Injectable hyaluronic acid hydrogel for minimal invasive bone augmentation
- 2011
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Ingår i: Journal of Controlled Release. - : Elsevier BV. - 0168-3659 .- 1873-4995. ; 152:2, s. 232-240
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Tidskriftsartikel (refereegranskat)abstract
- A strategy has been designed to develop hyaluronic acid (HA) hydrogel for in vivo bone augmentation using minimal invasive technique. A mild synthetic procedure was developed to prepare aldehyde modified HA by incorporating an amino-glycerol side chain via amidation reaction and selective oxidation of the pendent group. This modification, upon mixing with hydrazide modified HA formed hydrazone-crosslinked hydrogel within 30 s that was stable at physiological pH. In vitro experiments showed no cytotoxicity of hydrogel with the controlled release of active bone morphogenic protein-2 (BMP-2). In vivo evaluation of this gel as a BMP-2 carrier was performed by injecting gels over the rat calvarium and showed bone formation in 8 weeks in correlation with the amount of BMP-2 loaded (0, 1 and 30 pig) within the gel. Furthermore, hydrogels with 30 Kg of BMP-2 induced less bone formation upon subcutaneous injection in comparison with subperiosteal implantation. Histological examination showed newly formed bone with a high expression of osteocalcin, osteopontin and with angiogenic bone marrow when higher BMP-2 concentration was employed. Our result suggests that novel HA hydrogels could be used as a BMP-2 carrier and can promote bone augmentation for potential orthopedic applications.
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| 2. |
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| 3. |
- Hulsart-Billström, Gry, et al.
(författare)
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A uni-cortical femoral defect model in the rat : evaluation using injectable hyaluronan hydrogel as a carrier for bone morphogenetic protein-2
- 2015
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Ingår i: Journal of Tissue Engineering and Regenerative Medicine. - : Hindawi Limited. - 1932-6254 .- 1932-7005. ; 9:7, s. 799-807
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Tidskriftsartikel (refereegranskat)abstract
- The development of biomaterial for bone regeneration requires animal models that are reliable and designed to mimic clinically relevant situations. We have previously investigated hydrogels comprised of modified hyaluronic acid and polyvinyl alcohol in models of ectopic bone formation. This hydrogel induces bone regeneration when loaded with bone morphogenetic proteins (BMPs). To allow further optimization of hydrogels, we developed a new, femoral, non-critical-sized cortical defect model. In the rat femur, we drilled standardized, elongated unilateral cortical defects that did not require stabilization and that could be created bilaterally to allow paired comparisons of biomaterials. After optimizing the defect size, subsequent stress fractures occurred in only 8% and the defect healed partially over the 40 day study period. In a time-course experiment, we treated bone defects with the previously studied hyaluronan hydrogel loaded with 10 µg hydroxyapatite and 6 µg BMP-2. The shape of the defect allowed controlled containment of the material within the defect. The defect in the right leg was left untreated, while the left defect was filled with 40 µl of the BMP hydrogel. As determined by pQCT analysis, the treated defects had a higher bone mineral content, bone area and bone density than control defects. The relative difference was greatest between the groups at 10 and 20 days and diminished as the defect healed in the untreated legs. We conclude that this animal model allows facile and rapid screening of biomaterials for bone regeneration in cortical femoral defects without requiring external fixation.
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| 4. |
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| 5. |
- Lind, Monica, et al.
(författare)
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Exposure to pastures fertilised with sewage sludge disrupts bone tissue homeostasis in sheep
- 2009
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 407:7, s. 2200-2208
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Tidskriftsartikel (refereegranskat)abstract
- The femurs of male and female sheep (Ovis aries), aged 18 months, bred on pastures fertilized twice annually with sewage sludge (2.25 tonnes dry matter/ha; Treated; T)) or on pastures treated with inorganic fertilizer (Control; C) were studied, using peripheral Quantitative Computed Tomography (pQCT) and the three-point bending test. Males were maintained on the respective treatments from conception to weaning and then maintained on control pastures while the females were maintained on the respective treatments until slaughter. T rams exhibited increased total bone mineral density (BMD) at the metaphyseal part of femur (+10.5%, p<0.01) compared with C rams but had a reduced total cross sectional area (CSA, -11.5%, p<0.001), trabecular CSA (-17.1%, p<0.01) and periosteal circumference (-5.7%, p<0.001). In the mid-diaphyseal part, T rams had an increased total BMD (+13.8%, p<0.0001) and stiffness (+6.4%, p<0.01) but reduced total CSA (-12.1%, p<0.0001) and marrow cavity (-25.8%, p<0.0001), relative to C rams. In ewes although pQCT analysis of neither the metaphyseal nor the mid-diaphyseal part of the female femur bones showed any significant differences with treatment, the biomechanical method revealed a reduction in load at failure (-17.3%, p<0.01) and stiffness (-10.7%, p<0.05) amongst T ewes. It is concluded that exposure to pollutants present in sewage sludge can perturb bone tissue homeostasis in sheep, but particularly in males.
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| 6. |
- Bengtsson, G. J, et al.
(författare)
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Determination of Radiative Lifetimes In Neutral Arsenic Using Time-resolved Laser Spectroscopy In the Vuv Region
- 1992
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Ingår i: Astronomy & Astrophysics. - 0004-6361. ; 263:1-2, s. 440-442
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Tidskriftsartikel (refereegranskat)abstract
- Inspired by the recent Hubble Space Telescope first observations of arsenic in an astrophysical object we have determined the natural radiative lifetime of the upper states of two of the three resonance lines of As I. Short pulse laser excitation at 193.7 and 197.2 nm was achieved using different non-linear optical mixing schemes. Using time-resolved spectroscopy we obtain tau(4p(2)5s P-4(3/2))=4.3(5) ns and T(4p(2)5s P-4(1/2)=4.5(5)ns yielding the absorption oscillator strengths f(abs)(193.7 nm) =0.123 (17) and f(abs)(1 97.2 nm)=0.059(8).
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| 7. |
- Bengtsson, G. J, et al.
(författare)
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Determination of Radiative Lifetimes In Neutral Nitrogen Using Short Laser-pulses From A Distributed Feedback Dye-laser
- 1991
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Ingår i: Zeitschrift für Physik D Atoms, Molecules and Clusters. - 0178-7683. ; 22:1, s. 397-399
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Tidskriftsartikel (refereegranskat)abstract
- Radiative lifetimes were determined for two short-lived states in neutral nitrogen. Following photodissociation and two-photon excitation employing the same UV source, excitation to higher states was performed with a distributed feedback dye laser (DFDL). The lifetimes were found to be tau(2p2 4d4D7/2) = 17(3) ns and tau(2p2 5s4P5/2) = 22(3) ns.
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| 8. |
- Bengtsson, G. J, et al.
(författare)
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Natural Lifetimes of Excited-states of Neutral Nitrogen Determined By Time-resolved Laser Spectroscopy
- 1992
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 45:5, s. 2712-2715
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Tidskriftsartikel (refereegranskat)abstract
- Radiative lifetimes were determined for three quartet states of neutral nitrogen, and sequences of Rydberg states were studied using depletion spectroscopy. Free nitrogen atoms were generated by photodissociation of N2O using frequency-tripled dye-laser radiation that was two-photon resonant with the 2p(2)3p 4S or 4D states. Further quartet states were reached by a subsequent single-photon absorption. We obtain tau(2p(2)3p 4D7/2) = 44(2) ns, tau(2p(2)3p 4S3/2) = 26.0(1.5) ns, and tau(2p(2)6s4P5/2) = 41(7) ns.
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| 9. |
- Bengtsson, G. J, et al.
(författare)
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Oscillator-strengths For Resonance Transitions In Neutral Selenium and Tellurium Derived From Time-resolved Laser Spectroscopy
- 1992
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Ingår i: Zeitschrift für Physik D Atoms, Molecules and Clusters. - 0178-7683. ; 23:1, s. 29-32
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Tidskriftsartikel (refereegranskat)abstract
- We have measured radiative lifetimes for selenium and tellurium resonance levels by using short pulse laser excitation in differentially heated resonance cells. We obtained tau(3S1 Se I) = 2.9(5) ns and tau(3S1 Te I) = 3.1(5) ns, which together with branching ratio values given by Ubelis and Berzinsh yield the absorption oscillator strength f(abs)(Se I, 196.0 nm) = 0.074(16) and f(abs)(Te I, 214.3 nm) = 0.098(17).
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| 10. |
- Bengtsson, G. J, et al.
(författare)
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Radiative-lifetime and Lande-factor Measurements of the Se-i 4p(3)5s (5)s(2) Level Using Pulsed Laser Spectroscopy
- 1992
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Ingår i: Journal de Physique II. - : EDP Sciences. - 1155-4312 .- 1286-4870. ; 2:4, s. 773-779
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Tidskriftsartikel (refereegranskat)abstract
- First laser spectroscopic investigations on atomic selenium are reported. Natural selenium was thermally dissociated in a quartz resonance cell keeping the background pressure of abundant selenium molecules low by differential heating. The 4p35s5S2 level was excited by frequency-tripled pulsed-dye laser radiation at 207 nm. From time-resolved recordings of the fluorescence decay at 216 nm a natural radiative lifetime of 493(15) ns was determined, while quantum-beat and optical double-resonance measurements in an external magnetic field yielded g(J) = 2.0004(10) for the Lande factor. The results are compared with previous theoretical and experimental data.
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