bluuebunny/crossref_metadata_2025_split huggingface dataset:
What is a “Normal” wear pattern for metal‐on‐metal hip bearings?
Authors: Bowsher J. G. , Clarke I. C. , Williams P. A. , Donaldson T. K. 
Published: July 2009

AbstractIn addition to classical run‐in and steady‐state wear phases, metal‐on‐metal (MOM) hip bearings have encountered “runaway wear” (RAW) trends in simulator studies. This puzzling behavior has resulted in 2‐ to 19‐fold wear increases compared with other apparently “identical” bearings. MOM bearings have shown five identifiable RAW wear patterns in joint simulators; therefore, additional descriptive terms were used here to indicate various observed patterns, for example, “breakaway wear” (BAW), which was defined as a higher wear trend that recovers to steady‐state wear. As these trends commonly occur for MOM, this raises the question of what can be considered “normal” behavior or “abnormal”? In an effort to identify possible causes for this behavior, the current study investigated six Co‐Cr bearings, which closely matched with respect to geometrical tolerances. Despite close control of design and test variables, BAW occurred in 30% of the MOM bearings, producing a threefold wear increase above otherwise identical MOM bearings within the same group. The majority of the BAW (85%) occurred on the cup side and was validated by growth of wear scars and concentrations of metal ions. One bearing that showed continuing BAW at 5 Mc revealed a cup that was 50% smoother than other cups whereas its mating head was 50% rougher, thus signifying that highly polished areas were sites of the highest MOM wear. The two BAW bearings with high wear showed the greatest conformity at 5 Mc, in apparent contradistinction to classical lubrication theory. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
Angiogenic and inflammatory host response to surgical meshes of different mesh architecture and polymer composition
Authors: Laschke Matthias W. , Häufel Jörg M. , Scheuer Claudia , Menger Michael D. 
Published: July 2009

AbstractOne of the major challenges in hernia repair is the development of surgical meshes that guarantee an optimal biocompatibility and incorporation into the host tissue. For this purpose, it is necessary to study the impact of different mesh types on angiogenesis, inflammation, and tissue formation. In the present study, we analyzed the host tissue reaction to Prolene, Ultrapro, and Vicryl meshes over a 14‐day period after implantation into the hamster dorsal skinfold chamber using intravital fluorescence microscopy and histology. Our results demonstrate that compared with the Prolene and Ultrapro mesh, the Vicryl mesh induced a more pronounced angiogenic and inflammatory host tissue response with formation of a densely vascularized granulation tissue, which was infiltrated by many inflammatory cells. However, the strong foreign body reaction was not associated with a better mesh incorporation, but resulted in a significantly reduced explantation strength when compared with that of Prolene and Ultrapro meshes. Histological examinations revealed that the granulation tissue surrounding the Vicryl mesh was instable, because of low collagen content and massive infiltration of inflammatory cells. Thus, our data demonstrate that a stronger angiogenic and inflammatory response to an implanted mesh does not necessarily result in a better incorporation into the host tissue. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2009
Comparison of the response of cultured osteoblasts and osteoblasts outgrown from rat calvarial bone chips to nonfouling KRSR and FHRRIKA‐peptide modified rough titanium surfaces
Authors: Schuler Martin , Hamilton Douglas W. , Kunzler Tobias P. , Sprecher Christoph M. , de Wild Michael , Brunette Donald M. , Textor Marcus , Tosatti Samuele G. P. 
Published: July 2009

AbstractMimicking proteins found in the extracellular matrix (ECM) using specific peptide sequences is a well‐known strategy for the design of biomimetic surfaces, but has not yet been widely exploited in the field of biomedical implants. This study investigated osteoblast and, as a control, fibroblast proliferation to novel consensus heparin‐binding peptides sequences KRSR and FHRIKKA that were immobilized onto rough (particle‐blasted and chemically etched) commercially pure titanium surfaces using a poly(L‐lysine)‐graft‐poly(ethylene glycol) (PLL‐g‐PEG) molecular assembly system. This platform enabled a detailed study of specific cell–peptide interactions even in the presence of serum in the culture medium; thanks to the excellent nonfouling properties of the PLL‐g‐PEG surface. Cell‐binding peptide sequence RGD in combination with KRSR or FHRRIKA was used to examine a potentially‐enhanced or synergistic effect on osteoblast proliferation. Bare titanium and bioinactive surfaces (i.e., unfunctionalized PLL‐g‐PEG and scrambled KSSR, RFHARIK, and RDG) were used as control substrates. Additionally, in a newly developed experimental setup, freshly harvested bone chips from newborn rat calvariae were placed onto the same type of surfaces investigating size and pattern of osteoblast outgrowths. The findings of the current study demonstrated that the difference in osteoblast and fibroblast proliferation was influenced by surface topography more so than by the presence of surface‐bound KRSR and FHRRIKA. On the other hand, in comparison with the control surfaces, osteoblast outgrowths from rat calvarial bone chips covered a significantly larger area on RGD, KRSR, and FHRRIKA surfaces after 8 days and also migrated in an isotropic way unlike cells on the bioinactive substrates. Furthermore, the stimulatory effect of 0.75 pmol cm−2 RGD on osteoblast migration pattern could be enhanced when applied in combination with 2.25 pmol cm−2 KRSR. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
Enzyme‐catalyzed hydrolysis of dentin adhesives containing a new urethane‐based trimethacrylate monomer
Authors: Park Jong‐Gu , Ye Qiang , Topp Elizabeth M. , Spencer Paulette 
Published: July 2009

AbstractA new trimethacrylate monomer with urethane‐linked groups, 1,1,1‐tri‐[4‐(methacryloxyethylamino‐carbonyloxy)‐phenyl]ethane (MPE), was synthesized, characterized, and used as a comonomer in dentin adhesives. Dentin adhesives containing 2‐hydroxyethyl methacrylate (HEMA, 45% w/w) and 2,2‐bis[4(2‐hydroxy‐3‐methacryloyloxy‐propyloxy)‐phenyl] propane (BisGMA, 30% w/w) in addition to MPE (25% w/w) were formulated with H2O at 0 (MPE0), 8 (MPE8), and 16 wt % water (MPE16) to simulate the wet demineralized dentin matrix and compared with controls [HEMA /BisGMA, 45/55 w/w, at 0 (C0), 8 (C8), and 16 wt % water (C16)]. The new adhesive showed a degree of double bond conversion and mechanical properties comparable with control, with good penetration into the dentin surface and a uniform adhesive/dentin interface. On exposure to porcine liver esterase, the net cumulative methacrylic acid (MAA) released from the new adhesives was dramatically (p < 0.05) decreased relative to the control, suggesting that the new monomer improves esterase resistance. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2009
Inactivation of bacterial spores and viruses in biological material using supercritical carbon dioxide with sterilant
Authors: Qiu Qing‐Qing , Leamy Patrick , Brittingham Jennie , Pomerleau Jason , Kabaria Nimesh , Connor Jerome 
Published: July 2009

AbstractThe purpose of this study was to validate supercritical carbon dioxide (SC‐CO2) as a terminal sterilization method for biological materials, specifically acellular dermal matrix. In this study, bacterial spores, Bacillus atrophaeus, were inoculated onto porcine acellular dermal matrix to serve as a “worst case” challenge device. The inactivation of the spores by SC‐CO2 with peracetic acid (PAA) sterilant was analyzed as a function of exposure times ranging from 1 to 30 min. A linear inactivation profile for the Bacillus atrophaeus spores was observed, and a SC‐CO2 exposure time of 27 min was determined to achieve a sterility assurance level of 10−6. The inactivation of viruses was also studied using Encephalomyocarditis (EMC) viruses. After 15 min of exposure to SC‐CO2 with PAA sterilant, more than a 6 log10 reduction was observed for EMC viruses. Biochemical and biomechanical evaluations showed that the SC‐CO2 treatment with PAA sterilant did not cause significant changes in porcine acellular matrix's susceptibility to collagenase digestion, tensile or tear strength, indicating limited alteration of the tissue structure following SC‐CO2 sterilization. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2009
Prolonged antibiotic delivery from anodized nanotubular titanium using a co‐precipitation drug loading method
Authors: Yao Chang , Webster Thomas J. 
Published: July 2009

AbstractAdvances in nanotechnology have led to the development of novel orthopedic implant materials that not only have better cytocompatibility properties but can also be used as unique drug delivery platforms. In the present study, currently used titanium was anodized to possess nanotubular surface structures (80 nm inner diameter and 200 nm deep) capable of drug delivery. Such anodized nanotubular titanium surfaces promote bone cell functions (such as adhesion and differentiation) in vitro and in vivo compared with unanodized titanium. To achieve local drug delivery, anodized titanium with nanotubular structures were loaded with penicillin‐based antibiotics using a co‐precipitation method in which drug molecules were mixed in simulated body fluid to collectively precipitate with calcium phosphate crystals. Results showed for the first time that such co‐precipitated coatings on anodized nanotubular titanium could release drug molecules for up to 3 weeks whereas previous studies have demonstrated only a 150‐minute release of antibiotics through simple physical adsorption. Furthermore, drug release using co‐precipitation from anodized nanotubular titanium was determined to be a diffusion process dependent on first‐order kinetics. In addition, contrary to conventional thinking that penicillin‐based drug release should decrease cell functions (including both bacteria and mammalian cells), results of this study showed similar osteoblast (bone‐forming cell) adhesion between non‐drug loaded and drug loaded precipitated calcium phosphate coatings on anodized titanium. Due to the above, these findings represent a promising surface treatment for titanium that could be used for local drug delivery for improving orthopedic applications and, thus, should be studied further. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2009
Porosity and semipermeability of hemoglobin‐loaded polymeric nanoparticles as potential blood substitutes
Authors: Sheng Yan , Liu Changsheng , Yuan Yuan , Zhang Xiaolan , Shan Xiaoqian , Xu Feng 
Published: July 2009

AbstractPorosity and semipermeability, allowing life‐sustaining small molecules to penetrate, but hemoglobin (Hb) and other enzymes to cut off, predominantly affect the functionalities of the Hb‐loaded polymeric nanoparticles (HbPNPs) as blood substitutes. In this article, HbPNPs formulated in the size range of 110–122 nm were prepared by a modified double‐emulsion method with poly(lactic acid) (PLA)‐based polymers. The influences of the main preparation conditions, including solvent composition, stirring speed, Hb concentration and polymer matrix, on the porosity were investigated in details. To evaluate the porosity of HbPNPs, a novel nondestructive testing method based on molecular weight cut‐off (MWCO) was developed, and an effusion approach was applied to investigate the pore size in the particle shells with poly(ethylene glycol)s (PEGs) of different molecular weights (PEG200, PEG400, PEG600) as probes. Moreover,in vitrodiffusion behaviors of ascorbic acid and reduced glutathione from HbPNPs fabricated with various polymer matrices were studied. The MWCO of HbPNPs by changing solvent composition, stirring speed, Hb concentration, and polymer composition varied from 200 to 600, especially the PEGylation of the polymer, which exhibited obvious influence on the MWCO of HbPNPs. Ascorbic acid with molecular weight 176.1 could diffuse into PEGylated nanoparticles with mPEG content of 5–30 wt % freely, while reduced glutathione with molecular weight 307.3 could not penetrate when mPEG content reached 30 wt %. These results suggest that the HbPNPs optimized with MWCO between 400 and 600 can facilitate the transport of all those life‐sustaining small molecules. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
Preparation and characterization of calcium sulfate–biomimetic apatite nanocomposites for controlled release of antibiotics
Authors: Hesaraki Saeed , Moztarzadeh Fatollah , Nemati Roghayeh , Nezafati Nader 
Published: July 2009

AbstractIn the present study, release properties of antibiotic‐loaded cement‐type nanocomposites of biomimetic apatite and calcium sulfate were studied. Nanocrystalline component of the nanocomposite was synthesized by soaking a mixture of calcium phosphate reactants in tris‐buffered simulated body fluid (SBF). The release patterns of cephalexin and gentamicin from both pure calcium sulfate and nanocomposite cements into SBF were collected up to 144 h and fitted by Higuchi and Weibull equations. The effect of loaded antibiotics on physical properties of the cements was also evaluated. Fast release behavior of both antibiotics was obtained from calcium sulfate matrix, in which 80–85% of the loaded antibiotics were liberated during the first 10 h of elution. In contrast, an administered elution was acquired from nanonocomposite materials so that the release was controlled, in all cases, by a combined mechanism; major mechanism was drug diffusion through the matrix and the minor was matrix dissolution. The results showed that the initial setting time and injectability of cements were increased from 7 min and 71% for pure calcium sulfate cement (powder‐to‐liquid ratio = 2.5 g/mL) to 33 min and 95% for the nanocomposite cement containing 60 wt % apatite, respectively. The compressive strength of nanocomposite was about 0.9 MPa, nearly four times lower than that of pure calcium sulfate. In addition, the use of cephalexin monohydrate did not influence the setting time and compressive strength of the cements, whereas (adding) gentamicin sulfate significantly improved these properties. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
Measurement errors related to contact angle analysis of hydrogel and silicone hydrogel contact lenses
Authors: Read Michael L. , Morgan Philip B. , Maldonado‐Codina Carole 
Published: July 2009

AbstractThis work sought to undertake a comprehensive investigation of the measurement errors associated with contact angle assessment of curved hydrogel contact lens surfaces. The contact angle coefficient of repeatability (COR) associated with three measurement conditions (image analysis COR, intralens COR, and interlens COR) was determined by measuring the contact angles (using both sessile drop and captive bubble methods) for three silicone hydrogel lenses (senofilcon A, balafilcon A, lotrafilcon A) and one conventional hydrogel lens (etafilcon A). Image analysis COR values were about 2°, whereas intralens COR values (95% confidence intervals) ranged from 4.0° (3.3°, 4.7°) (lotrafilcon A, captive bubble) to 10.2° (8.4°, 12.1°) (senofilcon A, sessile drop). Interlens COR values ranged from 4.5° (3.7°, 5.2°) (lotrafilcon A, captive bubble) to 16.5° (13.6°, 19.4°) (senofilcon A, sessile drop). Measurement error associated with image analysis was shown to be small as an absolute measure, although proportionally more significant for lenses with low contact angle. Sessile drop contact angles were typically less repeatable than captive bubble contact angles. For sessile drop measures, repeatability was poorer with the silicone hydrogel lenses when compared with the conventional hydrogel lens; this phenomenon was not observed for the captive bubble method, suggesting that methodological factors related to the sessile drop technique (such as surface dehydration and blotting) may play a role in the increased variability of contact angle measurements observed with silicone hydrogel contact lenses. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
Evaluation of the efficacy of platelet‐rich plasma in delivering BMSCs into 3D porous scaffolds
Authors: Lei Hua , Xiao Ran , Tang Xiao Jun , Gui Lai 
Published: July 2009

AbstractPlatelet‐rich plasma (PRP), derived from autologous whole blood, is rich in fibrinogen and platelets, which release multiple active factors in response to thrombin. The purpose of this study was to evaluate the efficacy of PRP in delivering bone marrow stromal cells (BMSCs) into 3D porous scaffolds in comparison with platelet‐poor plasma (PPP) and Dulbecco's modified Eagle's medium (DMEM). The seeding efficacy, proliferation, and differentiation of the BMSCs seeded into poly(lactic‐co‐glycolic acid) (PLGA) porous scaffolds via PRP, PPP, and DMEM were tested. Additionally, BMSC/PLGA constructs were implanted in goat calvarial defects to radiologically and histologically detect the capability of PRP for enhancing bone regeneration. The results showed that the BMSC seeding efficacy of PRP was similar as that of PPP, and greater potential for in vitro BMSC proliferation and in vivo bone regeneration than PPP and DMEM. Therefore, PRP can potentially accomplish convenient and effective cell delivery into porous scaffolds, which is valuable in bone tissue engineering. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
In vitro characterization of bioactive titanium dioxide/hydroxyapatite surfaces functionalized with BMP‐2
Authors: Piskounova Sonya , Forsgren Johan , Brohede Ulrika , Engqvist Håkan , Strømme Maria 
Published: July 2009

AbstractPoor implant fixation and bone resorption are two of the major challenges in modern orthopedics and are caused by poor bone/implant integration. In this work, bioactive crystalline titanium dioxide (TiO2)/hydroxyapatite (HA) surfaces, functionalized with bone morphogenetic protein 2 (BMP‐2), were evaluated as potential implant coatings for improved osseointegration. The outer layer consisted of HA, which is known to be osteoconductive, and may promote improved initial bone attachment when functionalized with active molecules such as BMP‐2 in a soaking process. The inner layer of crystalline TiO2 is bioactive and ensures long‐term fixation of the implant, once the hydroxyapatite has been resorbed. The in vitro response of mesenchymal stem cells on bioactive crystalline TiO2/HA surfaces functionalized with BMP‐2 was examined and compared with the cell behavior on nonfunctionalized HA layers, crystalline TiO2 surfaces, and native titanium oxide surfaces. The crystalline TiO2 and the HA surfaces showed to be more favorable than the native titanium oxide surface in terms of cell viability and cell morphology as well as initial cell differentiation. Furthermore, cell differentiation on BMP‐2‐functionalized HA surfaces was found to be significantly higher than on the other surfaces indicating that the simple soaking process can be used for incorporating active molecules, promoting fast bone osseointegration to HA layers. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
Drug‐eluting stent with improved durability and controllability properties, obtained via electrocoated adhesive promotion layer
Authors: Levy Yair , Tal Noam , Tzemach Gilad , Weinberger Judah , Domb Abraham J. , Mandler Daniel 
Published: July 2009

AbstractDrug‐eluting stents (DES) have become an accepted technology in intravascular intervention. Manufacturing methodologies of DES are based mainly on mechanical processes, which tend to generate coatings that have poor stability properties; these were recently related as a potential hazard. A novel approach for significantly increasing the adhesion of polymer coatings onto DES is presented. The method is based on the electrochemistry of diazonium salts. These substances are organic compounds with the characteristic structure of R‐N X−, where R is an organic residue and X− is an anion. The objective of this article is to study the properties of a selected diazonium salt 4‐(1‐dodecyloxy)‐phenyldiazonium tetrafluoroborate, referred as C12‐phenyldiazonium. This material was found to be a superior adhesive promoter for polymeric coatings applied onto metallic stents. C12‐phenyldiazonium was synthesized and electrocoated on metallic stents and plates. The multilayer films of C12‐phenyldiazonium were further characterized through electrochemical (cyclic voltammetry, impedance spectroscopy), physical (light and scanning electron microscopy, X‐ray photoelectron spectroscopy, peeling tests), and chemical methodology (high pressure liquid chromatography). Further biocompatibility properties of the electrocoated basecoat were evaluated using in vitro and in vivo models. Synthesized C12‐phenyldiazonium was successfully electrocoated onto metallic surfaces. Electrochemical tests demonstrated its efficient and controllable electrocoating. C12‐phenyldiazonium was found to increase polymeric coating stability as was reflected by a standard adhesion test. Electrocoated metallic stents spray‐coated with a second polymeric film showed improved durability following incubation in physiological buffer. Furthermore, this improvement in durability exhibits stabilized drug release. In addition, biocompatibility evaluations have demonstrated basecoat's inert properties. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
A loading device suitable for studying mechanical response of bone cells in hard scaffolds
Authors: Zhang Chunqiu , Zhang Xizheng , Dong Xin , Wu Han , Li Guodong 
Published: July 2009

AbstractBone cells live in an environment heavily influenced by mechanical forces. Systematic study of cell's mechanical responses has relied greatly on the in‐vitro experiments due to complexity of internal environment of bone cells in vivo. A loading device suitable to hard scaffolds for studying mechanical responses of bone cells was made by using a kind of long‐travel, high‐load piezoelectric actuator. The device, which was precisely controlled by computer, and designed to work in an incubator at 37°C and 100% humidity, can cause hard scaffolds with directly compressive strains with more magnitudes, frequency components, and waveforms, including bone physiologically mechanical state. The experiment using hard scaffolds indicates the device validity. The device represents a versatile model that will provide conditions for investigating the effects of mechanical responses on bone cells in 3D hard scaffolds in vitro. In addition, the preliminary biological test was performed by the application of the device. The results showed that the dynamic compression with the amplitude of 1000 microstrain, the frequency of 3 Hz, the duration of 3 min/day enhanced the osteoblastic proliferation and extracellular matrix compared with static conditions, and improved the cell distribution within scaffolds. The researches of 3D mechanical effects on bone cells just in hard scaffolds similar to that in cancellous bone can enhance the understanding of bone physiology in vivo. The direct, dynamic contact‐loading of the device may provide an appropriate mechanical condition in bone tissue engineering culture. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009