bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunocytochemical analysis of dentin: A double‐labeling technique
Authors: Breschi L. , Gobbi P. , Lopes M. , Prati C. , Falconi M. , Teti G. , Mazzotti G. 
Published: September 2003

AbstractImmunocytochemical analysis is a fundamental and selective technique for identifying different molecular components of human dental structure. The hypothesis tested here is that the application of different etching solutions on dentin does not hinder collagen fibrils and proteoglycans from maintaining their immunochemical antigenicity. Human dentin disks were treated with 0.5M of EDTA, citric acid, maleic acid, or phosphoric acid (for 15 or 30 s). A double‐immunolabeling technique was performed to identify, simultaneously, collagen fibrils and chondroitin sulfate. The use of different acids resulted in different degrees of labeling. Maleic and citric acids revealed a diffuse and intense labeling for both collagen fibrils and proteoglycans. The use of phosphoric acid on dentin showed a massive coagulation of the proteoglycans (15 s) or very low labeling (30 s). These data clarify that the use of acids on dentin components is able to modify their antigenicity. Moreover, the double‐labeling immunocytochemical technique allows understanding of the spatial relationships between the collagen fibrils and proteoglycans of the dentin matrix. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 11–17, 2003
Biomimetic peptides that engage specific integrin‐dependent signaling pathways and bind to calcium phosphate surfaces
Authors: Gilbert Michele , Giachelli Cecilia M. , Stayton Patrick S. 
Published: September 2003

AbstractMany important matrix proteins involved in bone remodeling contain separate domains that orient the protein on hydroxyapatite and interact with target cell receptors, respectively. We have designed two synthetic peptides that mimic the dual activities of these large, complex proteins by binding to calcium phosphate minerals and by engaging integrin‐dependent signaling pathways in osteoblasts. The addition of either PGRGDS from osteopontin or PDGEA from collagen type I to the HAP‐binding domain of statherin (N15 domain) did not alter its α‐helical structure or diminish its affinity for hydroxyapatite. Immobilized N15‐PGRGDS bound MC3T3‐E1 osteoblasts predominantly via the αvβ3 integrin and induced focal adhesion kinase (FAK) phosphorylation at comparable levels to immobilized osteopontin. Immobilized N15‐PDGEA bound MC3T3‐E1 osteoblasts predominantly through the α2β1 integrin and induced similar levels of FAK phosphorylation. Although both peptides induced FAK phosphorylation with similar time courses, only the N15‐PDGEA peptide induced ERK1/2 phosphorylation, showing that these peptides are also capable of engaging integrin‐specific signaling pathways. This peptide system can be used to study adhesion‐dependent control of signaling in the context of the relevant biomineral surface and may also be useful in biomaterial and tissue engineering applications. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 69–77, 2003
Surface mechanical properties of pHEMA contact lenses: Viscoelastic and adhesive property changes on exposure to controlled humidity
Authors: Opdahl Aric , Kim Seong H. , Koffas Telly S. , Marmo Chris , Somorjai Gabor A. 
Published: September 2003

AbstractThe surface mechanical properties of poly(hydroxyethyl)methacrylate (pHEMA)‐based contact lenses were monitored as a function of humidity by atomic force microscopy (AFM). Surface viscoelastic and adhesion values were extracted from AFM force versus distance interaction curves and were found to be strongly dependent on the bulk water content of the lens and on the relative humidity. At low relative humidity, 40–50%, the dehydration rate from the surface is faster than the hydration rate from the bulk, leading to a rigid surface region that has mechanical properties similar to those measured on totally dehydrated lenses. At relative humidity values > 60%, the dehydration rate from the lens surface rapidly decreases, leading to higher surface water content and a softer surface region. The results indicate that, in an ocular environment, although the bulk of the pHEMA contact lens is hydrated, the surface region may be in a transition between a dehydrated glassy state and a hydrated rubbery state. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 350–356, 2003
Ex ova chick chorioallantoic membrane as a novel in vivo model for testing biosensors
Authors: Valdes T. I. , Klueh U. , Kreutzer D. , Moussy F. 
Published: September 2003

AbstractA major problem with implantable sensors is their short in vivo lifetime, due to strong tissue reactions (i.e., inflammation and fibrosis) caused by the implant and the failure of sensor components. The tissue reactions to the sensor, the biocompatibility of components, and the function of the sensor must be evaluated by using in vivo models. Current methods of in vivo biosensor testing are time‐ and labor‐ intensive and expensive. In addition, the results often vary on the basis of the surgical skills of the investigator. The in ova chorioallantoic membrane (CAM) of the developing chicken embryo was previously developed in our laboratory as a novel in vivo system to test biomaterials. In this new article, we describe a novel approach for testing biosensors in vivo using the ex ova CAM model as an alternative to the traditional mammalian models. Fertilized chicken eggs were incubated for 3 days in ova and then transferred into a petri dish (ex ova) for further incubation at 37°C and 80% humidity. After 1 week of incubation, acetaminophen biosensors, used as model sensors, were placed on top of the CAM and allowed to incorporate for 1 week. Biosensors were then tested for their sensitivity to acetaminophen. CAM venules were injected with 0.2 mL of a 3.6 mM acetaminophen solution. The current produced by the sensor reflected the change in blood acetaminophen levels. Sensors were also assessed by using gross and histological evaluations. We previously reported on the similarity of the tissue response of the CAM with the mammalian models. The low cost, simplicity, and possibility to continuously visualize the sensor test site through a cell culture dish make this animal model particularly attractive for the rapid in vivo screening of biosensors. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 215–223, 2003
Cementum engineering with three‐dimensional polymer scaffolds
Authors: Jin Q.‐M. , Zhao M. , Webb S.A. , Berry J.E. , Somerman M.J. , Giannobile W.V. 
Published: September 2003

AbstractCloned cementoblasts (OCCMs), periodontal ligament fibroblasts (SV‐PDLs), and dental follicle (SV‐F) cells obtained from mice were used as a tool to study periodontal tissue engineering. OCCM, SV‐PDL, and SV‐F cells were seeded onto three‐dimensional poly lactic‐co‐glycolic acid (PLGA) scaffolds and cultured with the use of bioreactors or implanted subcutaneously in severe combined immune deficiency (SCID) mice for up to 6 weeks. We explored the behavior of these cells in porous PLGA sponges by cell growth, expression of mineral‐associated genes using reverse transcriptase polymerase chain reaction, and mineralization by histologic analysis in vitro and in vivo. Results indicated that cells attached to PLGA scaffolds under either static or dynamic conditions in vitro. Only OCCM implants, retrieved from both in vitro bioreactors and SCID mice at 3‐and 6‐weeks post–cell implantation exhibited mineral formation. Types I and XII collagens, osteocalcin, and bone sialoprotein genes were detected in all implants retrieved from SCID mice. These results suggest that delivery of selected cells via PLGA scaffolds may serve as a viable approach for promoting periodontal tissue regeneration. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 54–60, 2003
Characterization and analysis of osteopontin‐immobilized poly(2‐hydroxyethyl methacrylate) surfaces
Authors: Martin Stephanie M. , Ganapathy Ramesh , Kim Tae K. , Leach‐Scampavia Deborah , Giachelli Cecilia M. , Ratner Buddy D. 
Published: September 2003

AbstractA wide array of technologies exist for the characterization and quantification of molecules present at surfaces. We have used several of these experimental and instrumental techniques for the analysis of a novel biomaterial surface. Osteopontin, an extracellular matrix molecule involved in wound‐healing processes, has been chosen as a relevant model protein to immobilize onto poly(2‐hydroxyethyl methacrylate) [poly(HEMA)]. Electron spectroscopy for chemical analysis and time‐of‐flight secondary ion mass spectrometry were used to verify the surface chemistry and the presence of protein. Iodination of osteopontin yielded quantitative data supportive of dose‐dependent immobilization. Enzyme‐linked immunosorbent assay was also used to investigate the presence of osteopontin on poly(HEMA). Finally, the cell adhesive properties of immobilized osteopontin were confirmed by using a bovine aortic endothelial cell adhesion assay. The use of multiple tools to characterize the many facets of a biomaterial surface will undoubtedly improve our understanding of the surface and facilitate the amelioration of in vivo performance. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 334–343, 2003
Action of microparticles of heparin and alginate crosslinked gel when used as injectable artificial matrices to stabilize basic fibroblast growth factor and induce angiogenesis by controlling its release
Authors: Chinen Naofumi , Tanihara Masao , Nakagawa Miyako , Shinozaki Keiko , Yamamoto Eriko , Mizushima Yutaka , Suzuki Yasuo 
Published: September 2003

AbstractAlginate is an acidic polysaccharide like the glycosaminoglycans and is a candidate for use as an artificial matrix. We developed a novel alginate gel sheet that is crosslinked with heparin (H/A gel sheet) and discovered its properties of releasing biologically active basic fibroblast growth factor (bFGF), a representative member of the heparin‐binding growth factors (HBGFs), for about 1 month in vitro and of inducing angiogenesis in vivo. In the present study, the H/A gel sheet was mechanically broken up to produce easily injectable 50‐ to 200‐μm microparticles of the gel (H/A gel particles), the properties of which were analyzed. The H/A gel particles cumulatively released 2.8 times as much bFGF as the H/A gel sheet, despite both having the same amount of bFGF adsorbed onto their gels. In addition, the bFGF‐adsorbed H/A gel particles released a significant amount of bFGF, which stimulated cellular growth in a culture of human umbilical venous endothelial cells for up to 5 weeks. The subcutaneous injection of the bFGF‐adsorbed H/A gel particles induced the formation of numerous microvessels in the tissue surrounding the gel. These results indicate that the H/A gel particles not only stabilize bFGF by preventing the occurrence of proteolysis or denaturation but also modulate its release from the gel. Because the H/A gel particles can be easily injected into the target tissues, this artificial matrix may be useful for the local delivery of HBGFs in the treatment of ischemic arterial diseases, as well as for regenerating or constructing tissues. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 61–68, 2003
Macroporous poly(N‐isopropylacrylamide) hydrogels with fast response rates and improved protein release properties
Authors: Cheng Si‐Xue , Zhang Jian‐Tao , Zhuo Ren‐Xi 
Published: September 2003

AbstractA series of temperature‐sensitive poly(N‐isopropylacrylamide) (PNIPA) hydrogels with large pore size and fast response were prepared by carrying out polymerizations in aqueous sodium chloride solutions with different concentrations. In comparison with conventional PNIPA hydrogels, the PNIPA gels thus prepared have remarkably larger swelling ratios below their lower critical solution temperature (LCST), and exhibit much faster response rates as the temperature is raised above their LCST. The improved properties are due to the presence of inorganic salt, NaCl, which leads the phase separation and formation of a heterogeneous porous structure during the polymerizations. The study on the drug release properties shows the macroporous hydrogels exhibit modulated release in response to temperature. The model protein, bovine serum albumin (BSA), can be released completely from the porous hydrogels at the temperature lower than the LCST because the pore size of the hydrogels is larger than the protein molecules. However, the release of BSA from the gels almost stops after a “burst” release in the initial stage at the temperature higher than the LCST because the pores are closed at the high temperature. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 96–103, 2003
Preserving the structure of adsorbed protein films for time‐of‐flight secondary ion mass spectrometry analysis
Authors: Xia Nan , Castner David G. 
Published: September 2003

AbstractThe characterization of adsorbed protein films with ultrahigh vacuum (UHV) surface analysis techniques requires dehydration of the samples, which can cause significant alterations in protein structure. It is desirable to preserve the structure of adsorbed protein films during drying, so UHV analysis could be done in a state that is more representative of proteins' actual structure in the aqueous environment. In this study, two methods, trehalose protection and glutaraldehyde fixation, were explored for their feasibility in preserving adsorbed protein structure for a powerful UHV surface analysis technique, time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS). Trehalose protection had shown some promise for ToF‐SIMS analysis in our previous study and was further examined with the model protein fibrinogen in this study. Using the combination of principal component analysis (PCA) and static ToF‐SIMS analysis, we found that trehalose protection could reduce the conformation change of fibrinogen upon drying, and prevent it from unfolding and exposing hydrophobic domains. Moreover, when the adsorbed protein film became more densely packed, the drying‐induced changes in protein structure were reduced. Thus, the protection afforded by trehalose coating was more significant at lower protein surface concentrations. The other method, glutaraldehyde fixation, was used in ToF‐SIMS analysis for the first time. The ϵ‐amino group of lysine was identified as the major reactive group in the protein structure toward glutaraldehyde fixation. Structural differences observed between fibrinogen films that were glutaraldehyde fixed before drying and after drying were similar to those observed between trehalose‐protected and‐unprotected dried fibrinogen films. Glutaraldehyde fixation was found to be a viable, alternative stabilizing method to trehalose protection for ToF‐SIMS analysis. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 179–190, 2003
Effect of flow perfusion on the osteogenic differentiation of bone marrow stromal cells cultured on starch‐based three‐dimensional scaffolds
Authors: Gomes Manuela E. , Sikavitsas Vassilios I. , Behravesh Esfandiar , Reis Rui L. , Mikos Antonios G. 
Published: September 2003

AbstractThis study aims to investigate the effect of culturing conditions (static and flow perfusion) on the proliferation and osteogenic differentiation of rat bone marrow stromal cells seeded on two novel scaffolds exhibiting distinct porous structures. Specifically, scaffolds based on SEVA‐C (a blend of starch with ethylene vinyl alcohol) and SPCL (a blend of starch with polycaprolactone) were examined in static and flow perfusion culture. SEVA‐C scaffolds were formed using an extrusion process, whereas SPCL scaffolds were obtained by a fiber bonding process. For this purpose, these scaffolds were seeded with marrow stromal cells harvested from femoras and tibias of Wistar rats and cultured in a flow perfusion bioreactor and in 6‐well plates for 3, 7, and 15 days. The proliferation and alkaline phosphatase activity patterns were similar for both types of scaffolds and for both culture conditions. However, calcium content analysis revealed a significant enhancement of calcium deposition on both scaffold types cultured under flow perfusion. This observation was confirmed by Von Kossa‐stained sections and tetracycline fluorescence. Histological analysis and confocal images of the cultured scaffolds showed a much better distribution of cells within the SPCL scaffolds than the SEVA‐C scaffolds, which had limited pore interconnectivity, under flow perfusion conditions. In the scaffolds cultured under static conditions, only a surface layer of cells was observed. These results suggest that flow perfusion culture enhances the osteogenic differentiation of marrow stromal cells and improves their distribution in three‐dimensional, starch‐based scaffolds. They also indicate that scaffold architecture and especially pore interconnectivity affect the homogeneity of the formed tissue. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 87–95, 2003
Microfabricated grooves recapitulate neonatal myocyte connexin43 and N‐cadherin expression and localization
Authors: Motlagh Delara , Hartman Thomas J. , Desai Tejal A. , Russell Brenda 
Published: September 2003

AbstractOur objective is to alter the surface topography on which cardiac myocytes are grown in culture so that they more closely resemble their in vivo counterparts. Microtextured silicone substrata were made using photolithography and microfabrication techniques and then coated with laminin. Primary cardiac myocytes from newborn rats were plated on microgrooved and nontextured substrata. Myocytes were highly oriented on 5 μm grooves (69.8 ± 2.0%) and significantly different, p < 0.0001, compared with randomly oriented cells grown on nontextured surfaces (2.9 ± 0.95%; n = 19). Cells on shallower, 2 μm, grooves were slightly less well oriented (46.9 ± 4.3%, n = 5, p < 0.001). The lateral spacings of the grooves were altered to examine changes in cell‐to‐cell contact by confocal immunocytochemistry and quantitative protein analysis. Connexin43 and N‐cadherin were distributed around the perimeter of the myocytes plated on 10×5×5 microgrooved surfaces, similar to the localization found in the neonate. Connexin43 expression in cultures on 5 μm deep grooved substrata was equal to the neonatal heart, whereas it differed in nontextured surfaces. We conclude that it is necessary to combine groove depth (5 μm) and lateral ridge dimensions between grooves (5 μm) in order to recapitulate connexin43 and N‐cadherin expression levels and subcellular localization to that of the neonate. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 148–157, 2003
Fourier transform infrared spectroscopy studies of alginate–PLL capsules with varying compositions
Authors: van Hoogmoed Chris G. , Busscher Henk J. , de Vos Paul 
Published: September 2003

AbstractMicroencapsulation of cells is a promising approach to prevention of rejection in the absence of immunosuppression. Clinical application, however, is hampered by insufficient insight into the factors that influence the biocompatibility of the capsules. Capsules prepared of alginates with a high guluronic (G) acid content proved to be more adequate for clinical application since they are more stable, but, unfortunately, they are less biocompatible than capsules prepared of intermediate‐G alginate. In order to get some insight into the physicochemical factors that influence the biocompatibility of capsules for the encapsulation of living cells, the chemical compositions of alginate–Ca beads and alginate–PLL capsules were studied by Fourier transform infrared spectroscopy. We found that during the transition of the alginate–Ca beads to alginate–PLL capsules, Ca connecting the alginate molecules, disappeared at the surface of both high‐G and intermediate‐G alginate–PLL capsules. At the same time, it turned out that high‐G alginate–PLL capsules contained more hydrogen bonding than did intermediate‐G alginate capsules. Thus the well‐known higher stability of high‐G alginate–PLL compared to intermediate‐G alginate–PLL capsules is not caused by a higher degree of binding to Ca of the alginate molecules but rather by the presence of more hydrogen bonds. Another observation was that after the transition from bead to capsule, high‐G alginate–PLL capsules contained 20% more PLL than the intermediate‐G alginate–PLL capsules. Finally, we show that in both high‐G and intermediate‐G alginate–PLL capsules, the PLL exists in the α‐helix, in the antiparallel β‐sheet, and in the random coil conformation. This study shows that FT‐IR allows for successful analyses of the chemical factors essential for understanding differences in the biocompatibility of alginate–PLL capsules. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 172–178, 2003
Size, shape, and composition of wear particles from metal–metal hip simulator testing: Effects of alloy and number of loading cycles
Authors: Catelas Isabelle , Bobyn J. Dennis , Medley John B. , Krygier Jan J. , Zukor David J. , Huk Olga L. 
Published: September 2003

AbstractThere has been a revived interest in metal–metal total hip replacements because of their potential for improved wear performance compared with conventional metal–polyethylene implants. The aim of the present study was to characterize metal wear particles isolated from metal–metal hip simulator testing of various clinically relevant alloys and to analyze the effects of these alloys and the number of loading cycles on wear particle characteristics. Implants were manufactured using medical‐grade cobalt–chromium–molybdenum (CoCrMo) alloys that were high‐carbon wrought, low‐carbon wrought, or cast (with solution annealing). Testing was performed in a MATCO orbital bearing hip simulator in 95% bovine calf serum. The wear particles were isolated from the serum at test periods of 0–0.25 million cycles (Mc) (run‐in wear) and 1.75–2 Mc (steady‐state wear) using an enzymatic protocol previously optimized to minimize particle changes due to reagents. Isolated particles embedded in epoxy resin were characterized by transmission electron microscopy (TEM) and energy dispersive X‐ray analysis (EDXA). The EDXA results revealed the predominance of “lighter” particles containing Cr and O (most likely chromium oxide particles from the passivation layer) and fewer darker CoCrMo particles, with varying ratios of Co and Cr (possibly from carbides and from implant matrix material). More CoCrMo particles were observed with the low‐carbon wrought alloy, but the majority of the particles for all three alloys was chromium oxides, especially for the 1.75–2 Mc test period. Image analysis of TEM micrographs revealed that for 0–0.25 Mc, there was up to 21% needle‐shaped particles but that the majority remained round to oval in shape, reflecting the predominance of chromium oxide particles. Particle length averaged about 52 ± 4 nm, with only small differences due to the alloy. For 1.75–2 Mc, most particles were round to oval in shape. They were even less needle‐shaped than at 0.25 Mc, and they had a slightly smaller length, averaging 46 ± 3 nm. In addition to characterizing the size and shape of particles from a MATCO simulator, this study is the first to demonstrate that particles that do not contain Co (presumably chromium oxides) can be predominant in the wear of metal–metal hip implants. It is therefore recommended that future in vitro and in vivo studies include the effects of these particles rather than just the effects of CoCrMo particles on the overall tissue response. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 312–327, 2003