bluuebunny/crossref_metadata_2025_split huggingface dataset:
Histocompatibility of photocrosslinked polyanhydrides: A novel in situ forming orthopaedic biomaterial
Authors: Poshusta Amy K. , Burdick Jason A. , Mortisen Derek J. , Padera Robert F. , Ruehlman Dana , Yaszemski Michael J. , Anseth Kristi S. 
Published: December 2002

AbstractCell–polymer interactions in subcutaneous and bony tissue were examined for a novel class of in situ forming and surface eroding polyanhydride networks. Specifically, photopolymerized disks of several polyanhydride compositions were implanted subcutaneously in rats, and the tissue was analyzed for an inflammatory response. The compositions elicited varied histological responses, ranging from highly active cell layers to moderate fibrous capsules, depending on the degrading polymer composition. Furthermore, one composition was photopolymerized in a model orthopaedic defect in the proximal tibia. The feasibility of photopolymerizing the methacrylated monomers in situ and the adherence of the photocrosslinked polyanhydride to the medullary canal were examined. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 62–69, 2003
Fabrication of micropored elastomeric film‐covered stents and acute‐phase performances
Authors: Nakayama Yasuhide , Nishi Shogo , Ueda‐Ishibashi Hatsue , Matsuda Takehisa 
Published: December 2002

AbstractTo prevent thrombus formation in the acute phase and restenosis in the subacute to chronic phase after stenting of atherosclerotic arteries, we developed a covered stent with a micropored elastomeric film, the blood‐contacting surface of which was coated with a photocured gelatin layer immobilized with heparin. Segmented polyurethane (SPU) film (30 μm in wall thickness) as a cover material was multiply micropored by excimer laser‐directed microprocessing (pore diameter, 30 μm; interpore distance, 125 μm). An aqueous mixed solution of benzophenone‐derivatized gelatin and heparin was coated on the micropored SPU film. Upon ultraviolet light irradiation, a thin layer of a gelatin gel immobilized with heparin was formed and simultaneously fixed on the SPU film. The fully covered stents were assembled by wrapping a balloon‐expandable stent with gelatin/heparin gel‐layered SPU film and subsequently suturing and then gluing. To assess the validity of this covered stent in vivo, “half‐covered” stents, in which half at the distal side was covered with the gel‐layered SPU film, was implanted in rabbit common carotid arteries (about 3 mm in diameter). After 3 months of implantation, all the half‐covered stents (n = 7) were patent. Regardless of the covered or noncovered region of the stents, the entire luminal surface of the stents was fully endothelialized and a thin neointimal tissue was formed. The potential advantages of a covered stent as designed above are discussed. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 52–61, 2003
Correlating fibronectin adsorption with endothelial cell adhesion and signaling on polymer substrates
Authors: Koenig Andrea L. , Gambillara Veronica , Grainger David W. 
Published: December 2002

AbstractFibronectin (Fn) adsorption was studied on different commercial polymer surface chemistries, including tissue culture polystyrene (TCPS), bacteriologic polystyrene (BPS), fluoropolymer Teflon AF®, and poly‐L‐lactide (PLLA). Antibody probes detected the availability of Fn's cell binding domain on adsorbed Fn in the competitive presence and absence of bovine serum albumin (BSA). Domain availability was highest for Fn adsorbed on TCPS, especially in the presence of either serum albumin or dilute serum. Attachment and growth efficiencies for human umbilical venous endothelial cells (HUVECs) cultured on surfaces preadsorbed with Fn in serum and serum‐free media correlated with antibody cell‐binding domain availability: TCPS > BPS, Teflon AF® > PLLA. Intracellular signaling from the GTPase, RhoA, was highest (RhoA:RhoGDI inhibitor ratio) in cells cultured on the Teflon AF® surfaces, indicating that despite lower attached cell numbers on Teflon AF® compared to TCPS, cell signaling remained activated after 24 h of growth. Up‐regulated cellular Fn mRNA messages, assessed using RT‐PCR techniques, supported HUVECs' producing the endogenous extracellular matrix (ECM) protein Fn in order to attach and survive on the suboptimal Teflon AF® culture surfaces. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 20–37, 2003
Controlling the spatial distribution of ECM components in degradable PEG hydrogels for tissue engineering cartilage
Authors: Bryant Stephanie J. , Anseth Kristi S. 
Published: December 2002

AbstractIn developing a scaffold to support new tissue growth, the degradation rate and mass loss profiles of the scaffold are important design parameters. In this study, hydrogels were prepared by copolymerizing a degradable macromer, poly(lactic acid)‐b‐poly(ethylene glycol)‐b‐poly(lactic acid) endcapped with acrylate groups (PEG‐LA‐DA) with a nondegradable macromer, poly(ethylene glycol) dimethacrylate (PEGDM). The resulting hydrogels exhibited a range of degradation behavior and mass loss profiles. Chondrocytes were photoencapsulated in gels formulated with 50:50, 25:75, and 15:85 (mol % PEGDM: mol % PEG‐LA‐DA) and cultured for 6 weeks in vitro. The neocartilaginous tissue formed was examined biochemically and histologically. After 6 weeks, the DNA content in gels with 75 and 85% degradable crosslinks was nearly twice that of the DNA content in the 50% gels. The total collagen content was significantly higher in the 85% gel [2.4 ± 0.8% wet weight (ww)] compared to the 50% gel (0.22 ± 0.29% ww). In examining the neocartilaginous tissue with immunohistochemistry, type II collagen was localized in the pericellular region in the 50% gel; however, when increased degradation was incorporated into the gel, type II collagen was found throughout the neotissue. In summary, the important role of hydrogel degradation in controlling and influencing the deposition and distribution of extracellular matrix molecules was demonstrated and quantified. © 2002 Wiley Periodicals, Inc., J Biomed Mater Res 64A: 70–79, 2003
Peptide‐modified p(AAm‐co‐EG/AAc) IPNs grafted to bulk titanium modulate osteoblast behavior in vitro
Authors: Barber Thomas A. , Golledge Stephen L. , Castner David G. , Healy Kevin E. 
Published: December 2002

AbstractInterpenetrating polymer networks (IPNs) of poly(acrylamide‐co‐ethylene glycol/acrylic acid) (p(AAm‐co‐EG/AAc) applied to model surfaces prevent protein adsorption and cell adhesion. Subsequently, IPN surfaces functionalized with the RGD cell‐binding domain from rat bone sialoprotein (BSP) modulated bone cell adhesion, proliferation, and matrix mineralization. The objective of this study was to utilize the same biomimetic modification strategy to produce functionally similar p(AAm‐co‐EG/AAc) IPNs on clinically relevant titanium surfaces. Contact angle goniometry and X‐ray photoelectron spectroscopy (XPS) data were consistent with the presence of the intended surface modifications. Cellular response was gauged by challenging the surfaces with primary rat calvarial osteoblast (RCO) surfaces in serum‐containing media. IPN modified titanium and negative control (RGE‐IPN) surfaces inhibit cell adhesion and proliferation, while RGD‐modified IPNs on titanium supported osteoblast attachment and spreading. Furthermore, the latter surfaces supported significant mineralization despite exhibiting lower levels of proliferation than positive control surfaces. These results suggest that with the appropriate optimization, this approach may be practical for surface engineering of osseous implants. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 38–47, 2003
Oxygenation of hypoxic region in solid tumor by administration of human serum albumin incorporating synthetic hemes
Authors: Kobayashi Koichi , Komatsu Teruyuki , Iwamaru Arifumi , Matsukawa Yasuko , Horinouchi Hirohisa , Watanabe Masazumi , Tsuchida Eishun 
Published: December 2002

AbstractRecombinant human serum albumin incorporating synthetic heme (rHSA‐FeP) was tested for its ability to increase O2 tension in the hypoxia of the solid tumor rat model. By the direct administration of the rHSA‐FeP solution (10 mL/kg) via the aorta descendens to the ascites hepatoma LY80 tumor on the right femur, the O2 tension of the hypoxic region immediately increased to 3.45 ± 1.43 Torr, which corresponds to a 2.4‐fold increase compared to that of the baseline value. These high O2 levels continued for 300 s after the infusion. The rHSA‐FeP solution can be utilized not only as a red blood cell substitute but also as an O2‐carrying medicine for the effective reoxygenation of the hypoxia solid tumor. © 2002 Wiley Periodicals Inc. J Biomed Mater Res 64A: 48–51, 2003
Influence of local complications on capsule formation around model implants in a rat model
Authors: Eltze E. , Bettendorf O. , Rody A. , Jackisch C. , Herchenröder F. , Böcker W. , Pfleiderer B. 
Published: December 2002

AbstractWe studied the capsule formation around various filled breast implants and other related changes in distant organs (e.g., liver, spleen, lymph nodes) in a rat model 3 and 6 months after implantation. Model implants, one per rat, (filled with saline, n = 19; silicone, n = 14; cohesive silicone, n = 17; and hydrogel, n = 19) were implanted subcutaneous in the lower back of rats. The animals were sacrificed regularly after 3 and 6 months of implantation or when wound defects occurred. The capsules and organs were examined histologically, and immunohistology of the capsules was performed. A monoclonal antibody specific for AIF‐1 (allograft inflammatory factor 1) was used to detect activated macrophages. Wound defects occurred most frequently after implantation of saline and hydrogel implants. Increased capsule thickness was associated with increased grade of inflammation, fibrosis, and the type of implant filling. There was a significant positive correlation between capsule thickness, presence of chronic inflammation, and AIF‐1‐positive macrophages (p < 0.0001), indicating that inflammation plays an important role in capsule formation. Remarkably, saline and silicone implants (in absence of local complications) cause only a blande slight fibrosis in capsules after 6 months of implantation, whereas capsules around cohesive silicone implants exhibited a more severe fibrosis with an increased capsule thickness. Most importantly, hydrogel seems to be most potent to induce an inflammatory infiltrate with AIF‐1 expressing macrophages at the implantation site, independent of implantation time, and capsules also produced a significant increase in thickness after 6 months. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 12–19, 2003
Plasma‐polymerized surfaces for culture of human keratinocytes and transfer of cells to an in vitro wound‐bed model
Authors: Haddow D. B. , Steele D. A. , Short R. D. , Dawson R. A. , Macneil S. 
Published: December 2002

AbstractThe aim of this study was to develop plasma‐polymerized surfaces suitable for the attachment and culture of human keratinocytes and that would allow their subsequent transfer to a wound‐bed model. Keratinocyte attachment has been assessed on a carrier polymer, either untreated or treated with a hydrocarbon plasma polymer, collagen I, or carboxylic‐acid‐containing plasma copolymers. Cell attachment was poor on the “bare” carrier polymer and hydrocarbon plasma polymer (PP) surfaces. Cell attachment was good and comparable on collagen I‐coated carrier polymer and carrier polymer plasma coated with carboxylic acid functionalities. After 24 h of cell culture, surfaces were inverted so that cells were adjacent to a de‐epidermalized dermis (DED) for 4 days. After 4 days in contact with DED, the surfaces were removed and the level of residual cells and cells transferred to DED were assessed using a cell viability assay. Cell transfer from the collagen I‐coated surface was on the order of 90%. Transfer from the carrier polymer surface and the hydrocarbon‐coated surface was poor while cells cultured on acid‐containing surfaces showed high levels of transfer. Cell transfer was greatest from those surfaces containing the highest level of acid functionality (ca. 21%). Cell transfer was not significantly affected by the choice of carrier polymer material although some sample‐to‐sample variation was seen. To determine that plasma‐polymerized surfaces could be used clinically, selected samples were sterilized with ethylene oxide. Subsequent analysis and cell culture indicated that the surface chemistry and cell‐transfer capability of these plasma‐polymerized surfaces were unaffected by the sterilization procedure. Plasma‐polymerized carboxylic‐acid‐containing surfaces show great promise in the field of wound healing, encouraging keratinocyte attachment and permitting keratinocyte transfer to a wound bed. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 80–87, 2003
Theoretical analysis of adsorption thermodynamics for charged peptide residues on SAM surfaces of varying functionality
Authors: Basalyga Dina M. , Latour Robert A. 
Published: December 2002

AbstractCellular response to an implant is largely controlled by protein adsorption because cells directly interact with the adsorbed protein rather than the implant surface. Protein adsorption will occur when the change in Gibbs free energy (ΔG) of the system decreases during the adsorption process. Electrostatic interactions between charged peptide residues presented by a protein's surface and surface functional groups greatly contribute to the ΔG of protein adsorption. In this study, semiempirical molecular orbital calculations were used to theoretically determine the adsorption enthalpy between charged peptide residues [aspartic acid (−1), glutamic acid (−1), and arginine (+1)] and functionalized SAM surfaces [methyl, hydroxyl, amine (+1), and carboxylic acid (−1)]. Additional enthalpic and entropic contributions attributed to water restructuring effects were then approximated based on literature values for functional group solvation and considered along with the calculated enthalpy values to estimate the change in ΔG for each residue/surface system as a function of surface separation distance. The results predict long‐range attraction and repulsion to the opposite and same‐charge residue/surface systems, respectively, followed by strong short‐range repulsion caused by functional group dehydration. Short‐range repulsion alone was predicted for the charged residues on the methyl and hydroxyl surfaces. These results provide a theoretical quantitative description of fundamental mechanisms governing protein adsorption behavior and provide a basis for the development of a knowledge‐based surface design approach to control biological response. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 120–130, 2003
Comparison of failure characteristics of a range of cancellous bone–bone cement composites
Authors: Lucksanasombool P. , Higgs W. A. J. , Ignat M. , Higgs R. J. E. D. , Swain M. V. 
Published: December 2002

AbstractOver the past decade, orthopedic surgery has embraced an increase in the depth of cement penetration into the adjacent cancellous bone structure. The resultant interdigitation transforms this zone into a thick layer of continuous interpenetrating composite material. The failure behavior of the composite formed with a number of potential bone cements with different bonding ability was investigated. The cancellous bone–cement composites exhibit considerable resistance to crack extension, and in situ optical observation indicates that the contribution of the cancellous bone is analogous to that of a typical fiber bridging process. The critical stress intensity factor and the work of fracture have been used to quantify the failure characteristics of the cancellous bone–cement composites. The nature of the crack propagation through these cement–bone composites was also captured via optical microscopy, and scanning electron microscopic images were taken of the failure surfaces. The R‐curve behavior, or crack extension characteristic, of the cancellous bone–cement composite was also determined. The interesting outcome is that the cancellous bone–PMMA (poly‐methylmethacrylate) composite, despite the absence of chemical bonding with bone, required the highest energy to fracture. In addition, the dimensional stability of the cement has a great effect on the interface. © 2002 Wiley Periodicals Inc. J Biomed Mater Res 64A: 93–104, 2003
Biomimetic PMMA‐based bone substitutes: A comparative in vitro evaluation of the effects of pulsed electromagnetic field exposure
Authors: Torricelli Paola , Fini M. , Giavaresi G. , Botter R. , Beruto D. , Giardino R. 
Published: December 2002

AbstractPulsed electromagnetic fields (PEMFs) are known to be effective in the stimulation of cultured osteoblasts and in vivo healing of delayed and nonunion fractures. In the present in vitro study the effects of PEMFs on osteoblastic cell cultures (MG63 human osteoblast‐like cells) grown in the presence of poly‐methylmethacrylate (PMMA) and of a biomimetic bone substitute made of a PMMA matrix added with alfa‐tricalcium phosphate (PMMA+α‐TCP) were evaluated, to assess the biological response at the cell‐biomaterial interaction. Cultures were stimulated with PEMFs (75 Hz, 2.3 mT, 1.3‐ms pulse duration) 12 h/day for 3 days and evaluations (MTT, ALP, OC, PICP, TGFβ‐1, IL‐6) were performed at 3 and 6 days. PMMA had a negative effect on osteoblasts, whereas PMMA+α‐TCP enhanced production of ALP, PICP, OC and TGFβ‐1, and reduced IL‐6 levels. Cells responded positively to PEMF stimulation even when cultured with a poorly biocompatible material, such as PMMA. This effect was more evident in the presence of PMMA+α‐TCP (further improvement in proliferation and synthetic activity) both at 3 and at 6 days. The properties of PMMA+α‐TCP look promising, and the present results support the use of PEMFs to improve tissue response to biomaterials implanted as bone substitutes. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 182–188, 2003
Differentiation of human bone‐derived cells grown on GRGDSP‐peptide bound titanium surfaces
Authors: Zreiqat H. , Akin F. Ahu , Howlett C. R. , Markovic B. , Haynes D. , Lateef S. , Hanley L. 
Published: December 2002

AbstractVarious surface modifications have been applied to titanium alloy (Ti‐6Al‐4V) implants, in an attempt to enhance osseointegration; crucial for ideal prosthetic fixation. Despite the numerous studies demonstrating that peptide‐modified surfaces influence in vitro cellular behavior, there is relatively little data reporting their effects on bone remodeling. The objective of this article was to examine the effects of chemically modifying Ti‐6Al‐4V surfaces with a common RGD sequence, a 15‐residue peptide containing GRGDSP (glycine‐arginine‐glycine‐aspartate‐serine‐proline), on the modulation of bone remodeling. The expression of proteins known to be associated with osseous matrix and bone resorption were studied during the growth of human bone‐derived cells (HBDC) on these peptide‐modified surfaces. HBDC grown for 7 days on RGD surfaces displayed significantly increased levels of osteocalcin, and pro‐collagen Iα1 mRNAs, compared with the production by HBDC grown on the native Ti‐6Al‐4V. A pattern that was also reflected at the protein levels for osteocalcin, type I collagen, and bone sialoprotein. Moreover, HBDC grown for 7 and 14 days on RGD‐modified Ti‐6Al‐4V expressed significantly higher level of osteoclast differentiation factors and lower levels of osteoprotegerin and IL‐6 proteins compared with other surfaces tested. These results suggest that different chemical treatments of implant material (Ti‐6Al‐4V) surface result in differential bone responses, not only their ability to form bone but also to stimulate osteoclastic formation. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 105–113, 2003
Low permeability biomedical polyurethane nanocomposites
Authors: Xu Ruijian , Manias Evangelos , Snyder Alan J. , Runt James 
Published: December 2002

AbstractIn this article we describe our continuing research on a novel nanocomposite approach for reducing gas permeability through biomedical polyurethane membranes. Nanocomposites were prepared using commercially available poly(urethane urea)s (PUU) and two organically modified layered silicates (OLS). Wide‐angle X‐ray diffraction experiments showed that the silicate layer spacing in the nanocomposites increased significantly compared with the neat OLS, signifying the formation of intercalated PUU/OLS structures. The nanocomposite materials exhibit increased modulus with increasing OLS content, while maintaining polymer strength and ductility. Water vapor permeability was reduced by about fivefold at the highest OLS contents, as a result of PUU/inorganic composite formation. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 114–119, 2003
Calcium and phosphate adsorption as initial steps of apatite nucleation on sol‐gel‐prepared titania surface
Authors: Coreño Juan , Martínez Antonia , Coreño Oscar , Bolarín Ana , Sánchez Félix 
Published: December 2002

AbstractTitania powders have been prepared by the sol‐gel route from Ti (IV) ethoxide under acidic conditions. Adsorption experiments of calcium and phosphate ions on gel‐derived titania suspensions were performed to suggest a likely initial step of apatite growth on its surface. Experiments were performed as a function of time and pH at 37°C with and without NaCl present in the suspensions. Also, zeta (ζ) potential experiments were performed to determine the kind of calcium adsorption. Results suggest that, apparently, calcium and phosphate adsorption can act as two different initial steps for apatite growth. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 131–137, 2003
Effect of chitosan film containing basic fibroblast growth factor on wound healing in genetically diabetic mice
Authors: Mizuno Keisuke , Yamamura Keiko , Yano Kohji , Osada Takashi , Saeki Satomi , Takimoto Norio , Sakurai Tsunehisa , Nimura Yuji 
Published: December 2002

AbstractBasic fibroblast growth factor (bFGF) has been shown to stimulate wound healing. However, consistent delivery of bFGF has been problematic. We studied the stability of bFGF incorporated into a chitosan film as a delivery vehicle for providing sustained release of bFGF. The therapeutic effect of this system on wound healing in genetically diabetic mice was determined as a model for treating clinically impaired wound healing. A chitosan film was prepared by freeze‐drying hydroxypropylchitosan (a water‐soluble derivative of chitosan) acetate buffer solution. Growth factor was incorporated into films before drying by mixing bFGF solution with the hydroxypropylchitosan solution. bFGF activity remained stable for 21 days at 5°C, and 86.2% of activity remained with storage at 25°C. Full‐thickness wounds were created on the backs of diabetic mice, and chitosan film or bFGF‐chitosan film was applied to the wound. The wound was smaller in after 5 days in both groups, but the wound was smaller on day 20 only in the bFGF‐chitosan group. Proliferation of fibroblasts and an increase in the number of capillaries were observed in both groups, but granulation tissue was more abundant in the bFGF‐chitosan group. These results suggest that chitosan itself facilitates wound repair and that bFGF incorporated into chitosan film is a stabile delivery vehicle for accelerating wound healing. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 64A:177–181, 2003