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- Andersson, Jonas, et al.
(författare)
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Optimal heparin surface concentration and antithrombin binding capacity as evaluated with human non-anticoagulated blood in vitro
- 2003
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Ingår i: Journal of Biomedical Materials Research. - : Wiley. - 0021-9304 .- 1097-4636. ; 67:2, s. 458-466
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Tidskriftsartikel (refereegranskat)abstract
- Contact between blood and a biomaterial surface takes place in many applications and is known to activate the coagulation and complement systems. Heparin surface coatings have been shown to reduce blood activation upon contact with artificial surfaces. To establish the optimal heparin surface concentration, blood was incubated in a tubing loop model at 37 degrees C. The tubing was coated with different surface concentrations of heparin and rotated at three different velocities. We demonstrate that the blood compatibility of a surface with regard to coagulation, complement, and platelet activation can be improved by increasing the heparin surface concentration in the 6-12 pmol antithrombin/cm2 concentration interval. The binding of factor H is not influenced by the increased heparin surface concentration, suggesting that this factor is not the primary regulator of complement on heparin surfaces. In addition, the heparin coating has no effect on the complement activation that occurs on gas surfaces in extracorporeal circuits.
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| 4. |
- Bergkvist, Magnus, et al.
(författare)
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Surface-dependent conformations of human plasma fibronectin adsorbed to silica, mica, and hydrophobic surfaces, studied with use of Atomic Force Microscopy
- 2003
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Ingår i: Journal of biomedical materials research. Part A.. - : Wiley. - 0021-9304 .- 1097-4636. ; 64:2, s. 349-356
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Tidskriftsartikel (refereegranskat)abstract
- Human plasma fibronectin (Fn) is a large flexible protein stabilized by intermolecular ionic interactions forming a compact structure. On altering solution conditions, the structure can revert to a more expanded state, thereby exposing previously hidden domains (e.g., cell-binding sites). Electron microscopy images of Fn air-sprayed onto mica surfaces show elongated protein structures, indicating a surface-induced structural change. This makes it interesting to investigate the influence of surface properties on the structure of adsorbed Fn. We have used intermittent-contact Atomic Force Microscopy to investigate the structure of Fn adsorbed onto mica, silica, and methylated silica surfaces. We observed that on silica surfaces, which is hydrophilic, most (70%) of the molecules had an elongated structure with partial intramolecular chain interactions, compare to molecules adsorbed on hydrophobic, methylated surfaces, where a compact structure predominated (70%). On mica surfaces, both compact and elongated protein structures were observed, with a slight preference for the elongated form (53%). Results show that surface physical properties influence the molecular structure of fibronectin on adsorption, which could provide useful information in understanding surface-induced in vivo responses.
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| 7. |
- Jedenmalm, Anneli, et al.
(författare)
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Effect of head surface roughness and sterilization on wear of UHMWPE acetabular cups
- 2009
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Ingår i: Journal of Biomedical Materials Research. - : Wiley. - 0021-9304 .- 1097-4636 .- 1549-3296 .- 1552-4965. ; 90:4, s. 1032-1042
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Tidskriftsartikel (refereegranskat)abstract
- The impact of femoral head surface roughness on wear of gamma-irradiation sterilized (3 MRad in nitrogen, crosslinked) and nonsterilized (not crosshnked) UHMWPE acetabular cups has been evaluated. Gravimetric wear testing was performed in a hip joint simulator for 2 x 10(6) cycles. CoCrMo heads were used with different surface roughness (R-a = 15 nm and R-a = 400 rim). The surface roughness after wear test was unchanged for the roughened heads, whereas the initially smooth heads showed a few scratches. The roughened heads increased the wear of the acetabular cups 2-fold. The gamma-irradiated cups tested against rough heads underwent the highest wear. The absorption of water was highest for the gamma-irradiated cups (0.0204% compared to 0.0031% after 85 days). Raman spectroscopy showed small but significant crystallinity changes in the wear zone, where the gamma-irradiated cups with the most extensive abrasion increased in crystallinity, whereas the nonsterilized cups underwent a crystallinity decrease.
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| 9. |
- Kjellson, Fred, et al.
(författare)
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Water uptake and release from iodine-containing bone cement.
- 2004
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Ingår i: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1552-4965 .- 0021-9304 .- 1097-4636. ; 71:2, s. 292-298
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Tidskriftsartikel (refereegranskat)abstract
- Water uptake and release characteristics of PMMA cement containing the water-soluble contrast media iohexol or iodixanol have been investigated. The water uptake study revealed that iohexol had the highest uptake of water (3.7%) and that iodixanol had an uptake close to that of Palacos(R) R (2.3% and 1.9%). The curves obtained showed the materials to follow classic diffusion theory, with an initial linearity with respect to t(1/2) making it possible to calculate the diffusion coefficients. This showed iohexol to have the lowest diffusion coefficient, Palacos(R) R the highest, and iodixanol close to that of Palacos(R) R. The release study showed that more iohexol than iodixanol was released from the bone cement; the long-term release was above 25 mug/ml, for iohexol compared to slightly above 10 mug/mL for iodixanol. A muCT investigation showed that the risk of developing an observable radiolucent zone is negligible. (C) 2004 Wiley Periodicals, Inc.
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| 10. |
- Larsson, Jenny, 1974-, et al.
(författare)
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Anti-inflammatory effects of a titanium-peroxy gel: role of oxygen metabolites and apoptosis.
- 2004
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Ingår i: Journal of biomedical materials research. Part A. - : Wiley. - 1549-3296 .- 0021-9304 .- 1097-4636. ; 68:3, s. 448-57
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Tidskriftsartikel (refereegranskat)abstract
- Polymorphonuclear neutrophils (PMN) are among the first inflammatory cells to arrive at an implant interface, where they encounter with the foreign material and may produce reactive oxygen species (ROS). During the interaction between titanium and ROS, titanium-peroxy (Ti-peroxy) compounds may be formed. We used a Ti-peroxy gel, made from titanium and hydrogen peroxide, to study the effects of Ti-peroxy compounds on PMN. In the absence of serum, the Ti-peroxy gel decreased the oxidative response of PMN to yeast and PMA and reduced PMN apoptosis without inducing necrosis. These effects could not be ascribed to the release of hydrogen peroxide from the Ti-peroxy gel, because a steady-state hydrogen peroxide producing system failed to mimic the effects of the gel. The effects were similarly unaffected when PMN were preincubated with beta(2)-integrin antibodies, questioning the involvement of adhesion molecules. Nevertheless, when a filter was used to separate the Ti-peroxy gel from the cells, the gel effect on PMN life span was abolished, pointing to a contact-dependent mechanism. In the presence of serum, the Ti-peroxy gel had no effect on the PMN oxidative response and life span, but appeared rather inert. In summary, this study demonstrates that the Ti-peroxy gel has potentially anti-inflammatory properties through a combined peroxide and physical contact effect, supporting the notion that interactions between titanium and inflammatory cells are responsible for the good performance of titanium in vivo.
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