| 1. |
- Gabriel, B. L., et al.
(författare)
-
Site-specific adhesion of Staphylococcus epidermidis (RP12) in Ti-Al-V metal systems
- 1994
-
Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612 .- 1878-5905. ; 15:8, s. 628-634
-
Tidskriftsartikel (refereegranskat)abstract
- Staphylococcus epidermidis (RP12) adhesion patterns were studied on the following titanium (Ti)-aluminium (Al)-vanadium (V) metal systems: (i) microfabricated samples consisting of Ti, Al and V islands deposited onto Ti or V substrata, (ii) pure Ti, Al and V metals, and (iii) medical grade Ti6Al4-V alloy. All of these surfaces were covered with their respective oxides formed upon exposure of the metals to air. Quantitative analysis of the number of cells bound per unit area indicates that S. epidermidis (RP12) exhibits greatest adhesion to pure V surfaces. When exposed to surfaces having controlled spatial variations in chemical composition on the 10 mu m scale (microfabricated samples), the bacteria preferentially populate V islands versus Ti or Al substrata. In the case of the biphasic Ti6Al4V alloy, the bacteria tend to adhere to V-rich, mixed phase regions and phase boundaries. These findings demonstrate that enhanced and preferential adhesion of S. epidermidis (RP12) occurs on V surfaces in TI-Al-V metal systems and suggest that bacterial interactions are influenced by surface oxide composition.
|
|
| 2. |
- Wesslén, Bengt, et al.
(författare)
-
Protein adsorption of poly(ether urethane) surfaces modified by amphiphilic and hydrophilic polymers
- 1994
-
Ingår i: Biomaterials. - : Elsevier BV. - 1878-5905 .- 0142-9612. ; 15:4, s. 278-284
-
Tidskriftsartikel (refereegranskat)abstract
- A commercial biomedical poly(ether urethane), Pellethane 2363-80AE, was surface modified through the use of amphiphilic polymeric additives, and through surface grafting with poly(ethylene glycol), PEG. Two different amphiphilic polymers, Polymer C and Pluronic PE9400, were used as additives. Polymer C, a segmented polyurethane, was prepared from PEG1500, 4,4'-diphenylmethane diisocyanate and a C-16-C18 monoglyceride chain extender. Pluronic PE9400 is a propylene oxide-ethylene oxide tri-block co-polymer obtained from BASF. Adsorption of human albumin and fibrinogen to the modified surfaces was studied by means of radiolabelled proteins. By contact angle measurements and X-ray photoelectron spectra the amphiphilic polymers were shown to accumulate at the polyurethane surfaces. Adsorption of fibrinogen, in particular, was significantly reduced by the amphiphilic additives to levels similar to those obtained for Pellethane surfaces grafted with PEG 20000. In vitro clotting times for citrate-buffered blood in contact with the amphiphilic surfaces increased as compared with the unmodified ones.
|
|
| 3. |
- Pekna, M, et al.
(författare)
-
Complement activation by polymethyl methacrylate minimized by end-point heparin attachment.
- 1993
-
Ingår i: Biomaterials. - 0142-9612 .- 1878-5905. ; 14:3, s. 189-192
-
Tidskriftsartikel (refereegranskat)abstract
- After intraocular lens implantation, despite good clinical results, many cataract patients develop a chronic uveitis, caused by an inflammatory response to the implant. One way to improve the biocompatibility of the intraocular lens is to modify the surface by end-point heparin attachment. This study shows that complement activation caused by poly(methyl methacrylate) can be diminished by end-point heparin attachment, as demonstrated by a significant reduction in the generation of C3a and fluid phase terminal complement complexes. It suggests that assessment of complement activation is a good indicator of the biocompatibility of intraocular lenses.
|
|
| 4. |
- Danielsen, Nils, et al.
(författare)
-
Inflammatory cells and mediators in the silicone chamber model for nerve regeneration
- 1993
-
Ingår i: Biomaterials. - 0142-9612. ; 14:15, s. 5-1180
-
Tidskriftsartikel (refereegranskat)abstract
- In the present study the inflammatory response was quantitatively evaluated during peripheral nerve regeneration. The fluid from silicone nerve regeneration chambers, inserted in rats, was collected during the early period of regeneration of transected sciatic nerves (6 h-7 d) and analysed with respect to inflammatory cells and mediators (leukotriene B4, LTB4, and interleukin-1 alpha, IL-1 alpha). Leucocytes were detected during the entire period (up to 7 d after implantation). The highest concentration was detected after 24 h. PMNG (polymorphonuclear granulocyte) was the predominant cell type in the chamber fluid during the initial 5d of regeneration. Analysis of the concentration of LTB4 demonstrated two peaks (at 24 h and 5 d). The IL-1 alpha concentration displayed an early and relatively smaller peak after 24 h and a second and much larger peak after 7 d, concomitant with an increase of the number of mononuclear cells.
|
|
| 5. |
- Messner, Karola, et al.
(författare)
-
Cartilage mechanics and morphology, synovitis and proteoglycan fragments in rabbit joint fluid after prosthetic meniscal substitution
- 1993
-
Ingår i: Biomaterials. - 0142-9612. ; 14:3, s. 163-168
-
Tidskriftsartikel (refereegranskat)abstract
- The effects of meniscal substitution with a Dacron® or Teflon® prosthesis on rabbit knee-joint cartilage were studied by indentation tests, gross and histological inspection, analysis of proteoglycan fragments in joint fluid and an evaluation of synovial changes. Cartilage mechanics and cartilage morphology were similarly abnormal after meniscectomy and meniscal substitution. The elevated concentrations of proteoglycan fragments in joint fluid and the more severe synovial changes in joints with a meniscal substitute, as compared to meniscectomy, probably resulted from irritation of the artificial implant, but also reflected the remaining effects from the necessary bone drilling. In this short-term experiment, the use of an artificial meniscal substitute could not prevent cartilage degeneration after meniscectomy.
|
|
| 6. |
- Lundgren, T, et al.
(författare)
-
Separation of non-collagenous proteins of bone formed in titanium implants: experimental study in the rabbit tibia, using a bone harvest chamber.
- 1990
-
Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612. ; 11:3, s. 216-8
-
Tidskriftsartikel (refereegranskat)abstract
- The non-collagenous proteins of mature cortical rabbit bone and 3 wk old bone specimens formed in titanium implant bone harvest chambers, were separated by means of fine pressure liquid chromatography. It was found that a sufficient amount of bone could be obtained from five bone harvest chambers in five rabbits during a period of 15 wk. A different protein chromatographic pattern was found in bone grown in bone harvest chambers as compared to normal cortical bone from the same region. This indicates a difference in bone quality and shows that this implant design can be used for biochemical analysis of bone formed adjacent to a biomaterial.
|
|
| 7. |
- Sennerby, Lars, 1960, et al.
(författare)
-
Influence of indomethacin on the regeneration of cortical bone within titanium implants in rabbits.
- 1993
-
Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612. ; 14:2, s. 156-8
-
Tidskriftsartikel (refereegranskat)abstract
- The influence of indomethacin on cortical bone regeneration was studied in bone harvest chambers made of commercially pure titanium and inserted in rabbit tibia. Newly formed bone was harvested in situ every 3 wk for 33 wk. Indomethacin (1 mg/kg body weight) was given daily as subcutaneous injections for two periods, followed by two control periods with no drug administration and the same schedule was followed for indomethacin at a dose of 4 mg/kg body weight. These indomethacin dosages did not statistically influence the cortical bone regeneration.
|
|
| 8. |
- Sennerby, Lars, 1960, et al.
(författare)
-
Tissue response to titanium implants in experimental antigen-induced arthritis.
- 1993
-
Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612. ; 14:6, s. 413-22
-
Tidskriftsartikel (refereegranskat)abstract
- The healing of threaded, non-alloyed titanium implants in bone was studied in an experimental model of monoarticular arthritis in New Zealand white rabbits. Immunization with bovine serum albumin (BSA) and repeated intra-articular injections with BSA elicited an immune response and clinical signs of inflammation. Implants were inserted and 6 wk after surgery, with full weight-bearing, the rabbits were killed by perfusion fixation. Light microscopic morphometry showed that the cartilage was thinner and the subchondral bone had a lower density in the arthritic joints compared to the control side. The titanium implants in the arthritic joints had a lesser degree of mineralized bone-implant contact and surrounding bone than the implants inserted in control joints. The present study shows that the healing of titanium implants in the rabbit knee joint is impaired in experimental immunologic arthritis. This model may be useful for the study of biomaterial-tissue interactions under pathological conditions.
|
|
| 9. |
- Larsson Wexell, Cecilia, 1965, et al.
(författare)
-
Bone response to surface modified titanium implants: studies on electropolished implants with different oxide thicknesses and morphology.
- 1994
-
Ingår i: Biomaterials. - 0142-9612. ; 15:13, s. 1062-74
-
Tidskriftsartikel (refereegranskat)abstract
- In a series of experimental studies, bone formation was analysed around systematically modified titanium implants. In the present study, machined, electropolished and anodically oxidized implants were prepared, surface characterized and inserted in the cortical bone of rabbits (7 wks and 12 wks). SEM, scanning Auger electron spectroscopy and atomic force microscopy revealed no differences in surface composition but marked differences in oxide thickness, surface topography and roughness. Light microscopic morphology and morphometry showed that all implants were in contact with bone, and had a large proportion of bone within the threads. The smooth, electropolished implants were surrounded by less bone than the machined implants with similar oxide thickness, (4-5 nm) and the anodically oxidized implants with thicker oxides (21 nm and 180 nm, respectively) after 7 wks. These studies show that a high degree of bone contact and bone formation can be achieved with titanium implants which are modified with respect to oxide thickness and surface topography. However, it appears that a reduction of surface roughness may influence the rate of bone formation in rabbit cortical bone.
|
|
