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The effect of the surface modification of titanium using a recombinant fragment of fibronectin and vitronectin on cell behavior
Ku, Y., C. P. Chung, et al. (2005), Biomaterials 26(25): 5153-7.
Abstract: The surface of titanium implants is in direct contact with host tissue and plays a critical role in determining biocompatibility. Fibronectin (FN) and vitronectin (VN) are major cell adhesive proteins found in the extracellular matrix (ECM) of various tissues, and in circulating blood. The aim of this study was to evaluate the engineered biomimetic surface of titanium by using recombinant fragment of FN(8-10) and VN(NTD) that contains the binding site for integrins. MC3T3-E1 cells seeded upon the FN(8-10)-coated titanium showed a marked increase in cell adhesion, proliferation, and differentiation over VN(NTD)-coated titanium. In addition, we confirmed that the surface properties of titanium prefer for FN(8-10) over VN(NTD) (p<0.05) in protein adhesion. These results suggest that the FN(8-10)-modified titanium surface can be used to improve the osseointegration of titanium implants by enhancing bone formation.

The effect of three different calcium phosphate implant coatings on bone deposition and coating resorption: a long-term histological study in sheep
Schopper, C., D. Moser, et al. (2005), Clin Oral Implants Res 16(3): 357-68.
Abstract: The present study investigated the hypothesis that hydroxyapatite (HA), tricalcium phosphate (TCP), and a HA-gel coated on endosseous titanium (Ti) implants by spark discharging (SD) and dip coating would achieve predictable osseointegration without evident bioresorption of the coatings on the long term. A costal sheep model was used for the implantation of the HA/SD, HA/TCP/SD, and HA-gel/SD specimens, which were retrieved 6 and 12 months following implantation. HA and Ti coatings on implants obtained by conventional plasma spraying (HA/PS, Ti/PS) were used as controls. Microscopy showed that osseointegration was achieved from all types of implants. No evidence for bioresorption of the HA/SD, HA/TCP/SD, and HA-gel/SD coatings was present but cohesive failure with disruption of the coating/implant interface was seen. A statistical analysis of the histomorphometrical data showed no time-dependent effect, however. HA/PS coatings achieved significantly higher bone-implant contact (BIC) percentages of the total implant surface (toBIC) than the other types of coatings (P=0.01). If the BIC percentages were traced separately for implant portions placed into cortical and cancellous bone (coBIC and caBIC, respectively), detailed analysis showed that the caBIC values of HA-gel/SD and HA/PS coatings were significantly higher than that of the other types of coatings (P=0.01). CaBIC values were highly correlated with toBIC values (P<0.001). The present study showed that the preparation techniques used produced thin, dense, and unresorbable coatings that achieved osseointegration. Compared with the control coatings, however, only HA-gel/SD coating can be recommended from the investigated preparation techniques for a future clinical use if a better coating cohesion is achieved.

The effects of a bioabsorbable barrier membrane containing safflower seed extracts on periodontal healing of 1-wall intrabony defects in beagle dogs
Song, W. S., C. S. Kim, et al. (2005), J Periodontol 76(1): 22-33.
Abstract: BACKGROUND: Recently, there has been much research done into the regenerative potential of materials used in oriental medicine. In several studies, evidence was found that these materials have an effect on bone regeneration. Among these materials, safflower seeds are of particular interest as they have been used for the treatment of blood stasis, bone fracture, and osteoporosis in traditional Korean medicine. In addition, they are known to have anti-inflammatory effects. The objective of this study is to evaluate the periodontal tissue regenerative effects of a bioabsorbable barrier membrane (polylactide glycolic acid electro-spun non-woven membrane) containing safflower seed extracts applied to surgically created 1-wall intrabony defects in beagle dogs. METHODS: One-wall intrabony defects were surgically created bilaterally at the mesial and distal sides of the mandibular second premolars and mesial side of the fourth premolars. These defects were randomly assigned either to the surgical control group which received a flap operation only or to one of two experimental groups consisting of defects which received a guided tissue regenerative procedure with either a bioabsorbable membrane (PLGA) or a bioabsorbable membrane containing safflower seed extracts (SSE/PLGA). The dogs were sacrificed 8 weeks after the operation, and a comparative histological examination was done. RESULTS: The new cementum formation was 2.49+/-0.41 mm in the surgical control group, 3.22+/-0.35 mm in the PLGA group, and 3.67+/-0.82 mm in the SSE/PLGA group. The extent of new cementum formation in barrier groups was significantly different from the surgical control group (P <0.05). The amount of intrabony cementum was 1.75+/-0.06 mm, 2.40+/-0.33 mm, and 2.70+/-0.81 mm for the surgical control group, the PLGA group, and the SSE/PLGA group, respectively; the amount of infrabony cementum in the barrier groups was significantly different from the surgical control group (P<0.05). The value of the suprabony cementum was 0.73+/-0.48 mm, 0.82+/-0.21 mm, and 0.97+/-0.09 mm for the surgical control group, the PLGA group, and the SSE/PLGA group, respectively, with no significant differences being observed among the treatments. The amount of new alveolar bone formation was 1.74+/-0.25 mm, 2.36+/-0.30 mm, and 2.64+/-0.74 mm for the surgical control group, the PLGA group, and the SSE/PLGA group, respectively, with a significant difference exhibited between the surgical control group and other groups (P <0.05). Superficial root resorption was often observed, but ankylosis was not present. CONCLUSION: Our results suggest that surgical application of polylactide glycolic acid non-woven membrane with or without safflower seed extract could promote the regeneration of alveolar bone and cementum in intrabony periodontal defects.

The effects of an atherogenic diet on macrophage/biomaterial interactions
Greisler, H. P., J. Ellinger, et al. (1991), J Vasc Surg 14(1): 10-23.
Abstract: We previously reported that biomaterials differentially induced macrophages to secrete growth factors that mediate reendothelialization. The present study evaluates the effect of an atherogenic diet on macrophage/biomaterial interactions. Female New Zealand white rabbits were fed an atherogenic diet. Peritoneal macrophages were harvested from these as well as rabbits fed a normal diet and cultured in Minimum Essential Medium with platelet-poor serum. Dacron or polyglactin 910 were added to two of three conditions of both cell groups in passage 2. Conditioned media were collected weekly through week 15. Mitogenicity assays were performed with quiescent mouse embryonal (BALB/c3T3) fibroblasts, atherosclerotic rabbit aortic smooth muscle cells, and murine capillary lung (LE-II) endothelial cells. Mitogenic activity was assayed by scintillation counting of tritiated thymidine incorporation into deoxyribonucleic acid (DNA). Results showed increased mitogenic activity released by macrophages from atherosclerotic rabbits, in the absence of prosthetic material, when assayed against every cell line. In normal diet macrophages, polyglactin 910 stimulated mitogen release for every cell line, and Dacron yielded minimal mitogen release. In lipid diet macrophages polyglactin 910 slightly increased mitogen release for all three cell lines, whereas Dacron resulted in stimulation of DNA synthesis in smooth muscle cells and BALB/c3T3 cells but less DNA synthesis in LE-II cells than in control, no graft material, media. Western blotting demonstrated immunoreactivity to basic fibroblast growth factor in media from normal diet macrophages but only in the presence of polyglactin 910 or Dacron. Radioimmunoassay for platelet-derived growth factor B chain was negative in all groups, and polymerase chain reaction techniques to amplify transforming growth factor-beta messenger ribonucleic was negative. These data demonstrate the effect of in vivo dietary manipulation on macrophage activation as well as the effect of an atherogenic diet in modulating macrophage/biomaterial interactions. Additionally, different biomaterials differentially induce macrophages to release factors that stimulate and inhibit growth.

The effects of calcium phosphate deposition upon corrosion of CoCr alloys and the potential for implant failure
Lewis, A. C. and P. J. Heard (2005), J Biomed Mater Res A 75(2): 365-73.
Abstract: Physical wear of orthopedic implants is inevitable. CoCr metal samples, typically used in joint reconstruction, corrode rapidly after removal of the protective oxide layer. The behavior of CoCr pellets immersed in human serum, fetal bovine serum (FBS), synovial fluid, and water were studied using time-of-flight secondary ion mass spectroscopy (ToF-SIMS). The differences in the corrosive nature of human serum, FBS, synovial fluid, and water after 5 days immersion were highlighted by the oxide/hydroxide layer, which was, respectively, 25, 10, 1.5, and 3-3.5 nm thick. The thickness of calcium phosphate deposit from human serum, FBS, and synovial fluid was, respectively, 30, 20, and 2 nm. Co and Cr ions migrated from the bulk metal surface and were trapped in the serum deposits, where chromium existed as oxides, hydroxides, and phosphates, whereas the cobalt chemistry was dominated only by phosphates and hydroxides. This may account for the composition of wear debris from CoCr orthopedic implants, which are predominantly hydroxyphosphate compounds. From the literature, proteoglycans, pyrophosphates, phospholipids, lubricin, and superficial zone protein (SZP) have been identified as possible causes for the insignificant deposit of calcium phosphate from synovial fluid. Circulation of these compounds around the whole implant may inhibit calcium phosphate deposition and therefore contribute to osteolysis.

The effects of collagen fiber orientation on the flexural properties of pericardial heterograft biomaterials
Mirnajafi, A., J. Raymer, et al. (2005), Biomaterials 26(7): 795-804.
Abstract: Improving cardiac valve bioprostheses (BHV) utilizing heterograft biomaterials requires a better understanding of their mechanical behavior. Flexure is a major mode of deformation for BHV leaflets during valve operation, inducing more complex deformation patterns within the tissue compared to tensile loads. In this study, we investigated the relation between collagen fiber preferred direction and the resulting flexural properties of native and glutaraldehyde-treated bovine pericardium. 20 mm x 4 mm strips were cut from the presorted sheets of bovine pericardium and divided into four groups: two directions of collagen fiber orientation in two groups of native and chemically treated specimens. Specimens were flexed in two different directions using a three-point bending technique (ASAIO J. 45(1999)59) and their flexural mechanical response compared. Results indicated that: (1) the relationship between the applied flexing moment and change of curvature of specimens was non-linear in both native and chemically fixed groups, (2) there were no directional differences in flexural properties when the bovine pericardium is flexed towards either the epi-pericardial or visceral surfaces in both native and chemically fixed specimens, (3) native and chemically fixed bovine pericardium were stiffer when flexed perpendicular to local preferred collagen fiber direction, and (4) chemical fixation increased the flexural rigidity of bovine pericardium. Results of this study indicate that the flexural properties of bovine pericardium are dominated by inter-fiber cross-links as opposed to the stiffness of the collagen fibers themselves. These findings can be used to guide the development of novel chemical treatment methods that seek to optimize biomechanical properties of heterograft biomaterials.

The effects of ligand chain length, salt concentration and temperature on the adsorption of bovine serum albumin onto polypropyleneglycol-Sepharose
Dias-Cabral, A. C., A. S. Ferreira, et al. (2005), Biomed Chromatogr 19(8): 606-16.
Abstract: The interaction thermodynamics associated with bovine serum albumin adsorption on polypropylene glycol (n=3)-Sepharose CL-6B and polypropylene glycol (n=7)-Sepharose CL-6B, using ammonium sulfate as the modulator was studied. Analysis of data under linear conditions was accomplished with the stoichiometric displacement retention model, preferential interaction approach and van't Hoff plots applied to HIC systems. Preferential interaction analysis indicated a strong entropic driving force under linear conditions, due to the release of a large amount of solvent on adsorption. In contrast, flow microcalorimetry under overloaded conditions showed that the adsorption of bovine serum albumin may be entropically or enthalpically driven. It is postulated that adsorption in the nonlinear region is influenced by the degree of water release, protein-protein interactions on the surface, reorientation of ligand, and conformational changes in the protein.

The effects of magnesium and ammonium additions on phosphate recovery from greenhouse wastewater
Yi, W., K. V. Lo, et al. (2005), J Environ Sci Health B 40(2): 363-74.
Abstract: Phosphorus recovery from greenhouse wastewater, using precipitation-crystallization, was conducted under three levels of calcium concentration, 304 mg/L (7.6 mmol/L), 384 mg/L (9.6 mmol/L), and 480 mg/L (12 mmol/L), and also with additions of ammonium and magnesium into the wastewater. Jar test results confirmed high phosphate removal, with more than 90% of the removal achieved with a pH as low as 7.7. Under the low calcium concentration, ammonium addition affected the chemical reactions at pH lower than 8.0, where struvite was produced; when the pH was raised to 8.8, other calcium compounds dominated the precipitation. Under the medium calcium concentration, ammonium and magnesium addition helped struvite precipitation in the low pH range. Hydroxyapatite (HAP) was the main product. Under the high calcium concentration, ammonium addition showed no effects on the precipitation.

The effects of particle size and surface coating on the cytotoxicity of nickel ferrite
Yin, H., H. P. Too, et al. (2005), Biomaterials 26(29): 5818-26.
Abstract: The safety and toxicity of nanoparticles are of growing concern despite their significant scientific interests and promising potentials in many applications. The properties of nanoparticles depend not only on the size but also the structure, microstructure and surface coating. These in turn are controlled by the synthesis and processing conditions. The dependence of cytotoxicity on particle size and on the presence of oleic acid as surfactant on nickel ferrite particles were investigated in vitro using the Neuro-2A cell line as a model. For nickel ferrite particles without oleic acid prepared by ball milling, cytotoxicity was independent of particle size within the given mass concentrations and surface areas accessible to the cells. For nickel ferrite particles coated with oleic acid prepared by the polyol method, the cytotoxicity significantly increased when one or two layers of oleic acid were deposited. Large particles (150+/-50 nm diameter) showed a higher cytotoxicity than smaller particles (10+/-3 nm diameter).

The efficiency of dexamethasone sodium phosphate-encapsulated chitosan microspheres after cold injury
Turkoglu, O. F., H. Eroglu, et al. (2005), Surg Neurol 64 Suppl 2: S11-6.
Abstract: OBJECTIVE: The aims of this study were to evaluate the efficiency of dexamethasone sodium phosphate (DSP) in the treatment of cold injury-induced brain edema and to compare systemic and topical application of DSP. METHODS: Sprague-Dawley rats weighing nearly 300 g were used in the experiments. Brain edema was formed by cold injury using metal sterile rods with a diameter of 4 mm that were previously cooled at -80 degrees C. Twenty-four hours after the injury, animals were decapitated and brain tissues were investigated by wet-dry weight method, lipid peroxidation ratio, and histological examination. RESULTS: The degree of edema was significantly lowered in groups in which DSP was administered using chitosan microspheres and by intraperitoneal route (P <.05). The statistical evaluation of the experimental results was performed using Mann-Whitney U test. Histological findings transmission electron microscopy (TEM) correlated with the quantitative results. CONCLUSION: Both intraperitoneal- and microsphere-administered DSP were found to be very effective in a cold injury brain edema model. The authors believe that future studies should lead to new applications of the microsphere formulations prepared by chitosan as the matrix material in many other therapies.

The electrochemical evaluation of a Zr-based bulk metallic glass in a phosphate-buffered saline electrolyte
Morrison, M. L., R. A. Buchanan, et al. (2005), J Biomed Mater Res A 74(3): 430-8.
Abstract: Bulk metallic glasses (BMGs) represent an emerging class of materials with an amorphous structure and a unique combination of properties. The objectives of this investigation were to define the electrochemical behavior of a specific Zr-based BMG alloy in a physiologically relevant environment and to compare these properties to standard, crystalline biomaterials as well as other Zr-based BMG compositions. Cyclic-anodic-polarization studies were conducted with a Zr52.5Cu17.9Ni14.6Al10.0Ti5.0 (at %) BMG in a phosphate-buffered saline electrolyte with a physiologically relevant oxygen content at 37 degrees C. The results were compared to three common, crystalline biomaterials: CoCrMo, 316L stainless steel, and Ti-6Al-4V. The BMG alloy was found to have a lower corrosion penetration rate (CPR), as compared to the 316L stainless steel, and an equivalent CPR, as compared to the CoCrMo and Ti-6Al-4V alloys. Furthermore, the BMG alloy demonstrated better localized corrosion resistance than the 316L stainless steel. However, the localized corrosion resistance of the BMG alloy was not as high as those of the CoCrMo and Ti-6Al-4V alloys in the tested environment. The excellent electrochemical properties demonstrated by the BMG alloy are combined with a low modulus and unparalleled strength. This unique combination of properties dramatically demonstrates the potential for amorphous alloys as a new generation of biomaterials.

The engineering of biomaterials exhibiting recognition and specificity
Ratner, B. D. (1996), J Mol Recognit 9(5-6): 617-25.
Abstract: Although synthetic materials are now widely used in implanted medical devices, they are not engineered for recognition and specificity. This article considers the design of polymer surfaces that might be specifically recognized and trigger normal healing pathways. The technological advances that will contribute to biorecognition biomaterials include surfaces to inhibit non-specific interactions, self-assembly to create ordered surface structures and strategies to place recognition sites on surfaces by random arrays of groups and by templates.

The enhancement of osteoblast growth and differentiation in vitro on a peptide hydrogel-polyHIPE polymer hybrid material
Bokhari, M. A., G. Akay, et al. (2005), Biomaterials 26(25): 5198-208.
Abstract: The objective of this study was to investigate the effect of combining two biomaterials on osteoblast proliferation, differentiation and mineralised matrix formation in vitro. The first biomaterial has a well-defined architecture and is known as PolyHIPE polymer (PHP). The second biomaterial is a biologically inspired self-assembling peptide hydrogel (RAD16-I, also called PuraMatrix) that produces a nanoscale environment similar to native extracellular matrix (ECM). Our work investigates the effect of combining RAD16-I with two types of PHP (HA (Hydroxyapatite)-PHP and H (Hydrophobic)-PHP) and evaluates effects on osteoblast growth and differentiation. Results demonstrated successful incorporation of RAD16-I into both types of PHP. Osteoblasts were observed to form multicellular layers on the combined biomaterial surface and also within the scaffold. Dynamic cell seeding and culturing techniques were compared to static seeding methods and produced a more even distribution of cells throughout the constructs. Cells were found to penetrate the scaffold to a maximum depth of 3 mm after 35 days in culture. There was a significant increase in cell number in H-PHP constructs coated with RAD16-I compared to H-PHP alone. Our results show that RAD16-I enhances osteoblast differentiation and indicates that the incorporation of this peptide provides a more permissive environment for osteoblast growth. We have developed a microcellular polymer containing a nanoscale environment to enhance cell: biomaterial interactions and promote osteoblast growth in vitro.

The evaluation of processed cancellous bovine bone as a bone graft substitute
Worth, A., M. Mucalo, et al. (2005), Clin Oral Implants Res 16(3): 379-86.
Abstract: OBJECTIVE: To determine the ability of a novel bovine cancellous bone xenoimplant to act as an osteoconductive graft in an ovine femoral defect model. An autograft harvested from the xenoimplant site was placed in a contralateral limb defect for comparison. MATERIAL AND METHODS: The xenoimplant used had been rendered immunologically inert by a novel defatting and deproteinating process. Following surgical implantation of cores into condylar cancellous bone defects, fluorochrome labels were administered to 12 sheep at 2 1/2, 4 1/2 and 8 weeks. Incorporation of the xenoimplants and autografts into the host bone was compared radiographically and histomorphometrically at 10 weeks. RESULTS: Radiographically, the degree of osteointegration was comparable. Histomorphometric data, consisting of labelled surface (LS) estimates, confirmed osteoconductive properties of both the xenoimplants and autografts. Remodelling activity was greatest in the xenoimplants at 2 1/2, weeks. At 4 1/2 weeks, there was more activity in the autograft, but by 8 weeks they were performing similarly. Xenoimplant-LS estimates were comparable or greater than those of the autograft at all times. CONCLUSIONS: Processed bovine cancellous bone xenoimplants were osteoconductive in this model and show promise for development as a biomaterial in human and veterinary orthopaedic surgery.

The evolution of allograft bone for spinal applications
Grauer, J. N., J. M. Beiner, et al. (2005), Orthopedics 28(6): 573-7; quiz 578-9.

The evolution of hip resurfacing arthroplasty
Grigoris, P., P. Roberts, et al. (2005), Orthop Clin North Am 36(2): 125-34, vii.
Abstract: Metal-on-metal hip resurfacing, a significant recent development in hip arthroplasty, preserves proximal femoral bone stock, optimizes stress transfer to the proximal femur, and offers inherent stability and optimal range of movement. The results of hip resurfacing in the 1970s and 1980s were disappointing, and the procedure was largely abandoned by the mid-1980s. The renaissance of metal-on-metal articulations for total hip arthroplasty has enabled the introduction of new hip resurfacings, and many implant manufacturers have introduced such systems. Early results are encouraging, and complications commonly seen in the 1970s and 1980s, such as early implant loosening and femoral neck fracture, are rare. Background research and better understanding of implant failure suggest that current hip resurfacing technology has developed beyond that of an experimental procedure.

The evolution of soft tissue fillers in clinical practice
Murray, C. A., D. Zloty, et al. (2005), Dermatol Clin 23(2): 343-63.
Abstract: To remain experts in skin care and treatment, every dermatologist must be aware of the evolving role of soft tissue fillers in dermatology. Patients with facial scarring, lipodystrophy, contour abnormalities, and age- and sun-induced rhytids can be successfully treated. A literature review, industry recommendations, and the authors' experience serve to highlight fillers most appropriate for each patient's complaint. Newer agents, including the hyaluronic acids and human collagens, and long-lasting materials, such as polymethlymethracrylate and calcium hydroxlyapatite, are reviewed. This discussion of the specific risks, indications, and technical pearls for the various fillers will allow clinicians to accurately advise or treat patients.

The examination of polysaccharides as potential antioxidative compounds for topical administration using a lipid model system
Trommer, H. and R. H. Neubert (2005), Int J Pharm 298(1): 153-63.
Abstract: Aim of this study was the detection of polysaccharides with antioxidative properties as potential lipid protectors for topical administration. The effects of eight different polysaccharides on UV irradiation induced lipid peroxidation were investigated in a concentration dependent manner. An aqueous linolenic acid dispersion was used as an in vitro test system to examine the influences of acacia gum, agar agar, alginic acid, guar gum, novelose 330 and xanthan gum on the lipid peroxidation level after UV exposure. Four different samples of pectin and locust bean gum resulting from a swing mill grinding series were tested as well. Iron ions were added as transition metal catalysts. A UV irradiation device was used to create high level radiation. The amount of lipid peroxidation secondary products was quantified by the thiobarbituric acid assay detecting malondialdehyde. All of the tested polysaccharides showed antioxidative effects at least at one concentration. For acacia and xanthan gum, a concentration dependency of the protective effects was measured. The samples of agar agar, guar gum and novelose 330 acted antioxidatively without showing any concentration dependency. For alginic acid, prooxidative effects were determined. A correlation between grinding time and the effects of pectin and locust bean gum on the model lipid was not observed. The administration of lipid protective polysaccharides in cosmetic formulations or sunscreens could be helpful for the protection of the human skin against UV induced damage. In vivo experiments with the lipid protective polysaccharides found in this study should follow.

The fallacy of evaluating biomaterial wear-rates with water as lubricant: a hip simulator study of alumina-PTFE nd CoCr-PTFE combinations
Phipatanakul, W. P., S. A. Johnson, et al. (1998), J Biomed Mater Res 39(2): 229-33.
Abstract: Controversy surrounds wear data from hip-simulator studies, whether from the choice of lubricants or other parameters such as the particular biomaterial combinations used, and whether any such interactions could bias the resulting wear predictions. To investigate these phenomena, we studied the wear performance of CoCr and alumina femoral heads, in water and serum-based lubricants, using as our standard the polytetrafluoroethylene wear data derived clinically by Charnley. To model Charnley's clinical experience, PTFE acetabular cups were used in sets of three each with each size of femoral head for 22.25, 28, and 42-mm diameters in a nine-channel hip simulator. From the serum-based tests, the CoCr-PTFE wear data were consistently linear with duration of test, exhibited very large wear rates of 3,000-8,400 mm3/10(6), cycles had a precision within +/- 4% for each set of three cups, and copious amounts of small particulate were clearly seen circulating. The wear data clearly demonstrated Charnley's thesis that volume of wear increased with regard to size of femoral head. From the water-based tests, the CoCr-PTFE wear data were nonlinear with duration of test, had much reduced wear rates compared to the serum tests, lost the clinical relationship with ball size, and precision deteriorated to +/- 27% for each set. The wear debris appeared as 1-2 cm long ribbons which floated to the surface. For the alumina-PTFE combination in serum, the wear data appeared identical in performance to the CoCr-PTFE data in serum. Thus, the PTFE wear rates were not sensitive to the choice of femoral-head material. The most surprising outcome in this study was the zero-wear performance of the ceramic-PTFE combination in water. This contrasted remarkably with the large wear rates established for the same combinations run in serum. The zero-wear performance of the ceramic-PTFE combination in water was unexpected, but a similar phenomenon was noted in published simulator tests of ceramic-UHMWPE run in water. It now seems likely that such data may reflect the capricious behavior of water lubrication rather than any other variables under evaluation. The water-based experiments clearly favored the ceramic's superior tribological performance and placed metal bearings at a decided disadvantage. Therefore, for an in vitro simulation of materials wear-ranking of clinical relevance, it may be advisable to use a serum-based lubricant.

The fate of fibrinogen following adsorption at the blood-biomaterial interface
Brash, J. L. (1987), Ann N Y Acad Sci 516: 206-22.

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