bluuebunny/crossref_metadata_2025_split huggingface dataset:
Floodplain friction parameterization in two‐dimensional river flood models using vegetation heights derived from airborne scanning laser altimetry
Authors: Mason David C. , Cobby David M. , Horritt Matthew S. , Bates Paul D. 
Published: June 2003

AbstractTwo‐dimensional (2‐D) hydraulic models are currently at the forefront of research into river flood inundation prediction. Airborne scanning laser altimetry is an important new data source that can provide such models with spatially distributed floodplain topography together with vegetation heights for parameterization of model friction. The paper investigates how vegetation height data can be used to realize the currently unexploited potential of 2‐D flood models to specify a friction factor at each node of the finite element model mesh. The only vegetation attribute required in the estimation of floodplain node friction factors is vegetation height. Different sets of flow resistance equations are used to model channel sediment, short vegetation, and tall and intermediate vegetation. The scheme was tested in a modelling study of a flood event that occurred on the River Severn, UK, in October 1998. A synthetic aperture radar image acquired during the flood provided an observed flood extent against which to validate the predicted extent. The modelled flood extent using variable friction was found to agree with the observed extent almost everywhere within the model domain. The variable‐friction model has the considerable advantage that it makes unnecessary the unphysical fitting of floodplain and channel friction factors required in the traditional approach to model calibration. Copyright © 2003 John Wiley & Sons, Ltd.
The inhibitory activity of serum to prevent bacterial adhesion is mainly due to apo‐transferrin
Authors: Ardehali Reza , Shi Lei , Janatova Jarmila , Mohammad S. Fazal , Burns Gregory L. 
Published: June 2003

AbstractA marked, up to 5‐fold, reduction in bacterial adhesion to Tecoflex® polyurethane (PU) surfaces was observed in the presence of bovine/human serum or plasma at 0.5% or higher concentrations in the medium. Further investigation of the phenomenon resulted in identification, isolation, and characterization of the serum component with the ability to significantly reduce bacterial adhesion. Upon fractionation of bovine serum by an anion exchange chromatography, protein pools were made and analyzed by immunoelectrophoresis and by polyacrylamide gel electrophoresis in the presence of SDS and were examined for their effect on the adhesion of Staphylococcus epidermidis to PU surfaces. The pool exhibiting a significant inhibitory effect was subjected to further biochemical tests, which resulted in the identification of transferrin (Tf) as its predominant protein. Bacterial adhesion studies in the presence of purified Tf revealed that holo‐Tf (iron‐containing form) had no influence on bacterial adhesion at any concentration. Only apo‐Tf (iron‐lacking form) exerted the inhibitory effect, in a dose responsive manner at concentrations of 10 μg/mL or higher. Bacteria remained viable when suspended at the low apo‐Tf concentrations, sufficient to prevent bacterial adhesion. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 21–28, 2003
Elastic biodegradable poly(glycolide‐co‐caprolactone) scaffold for tissue engineering
Authors: Lee Soo‐Hong , Kim Byung‐Soo , Kim Soo Hyun , Choi Sung Won , Jeong Sung In , Kwon Il Keun , Kang Sun Woong , Nikolovski Janeta , Mooney David J. , Han Yang‐Kyoo , Kim Young Ha 
Published: June 2003

AbstractCyclic mechanical strain has been demonstrated to enhance the development and function of engineered smooth muscle (SM) tissues, and it would be necessary for the development of the elastic scaffolds if one wishes to engineer SM tissues under cyclic mechanical loading. This study reports on the development of an elastic scaffold fabricated from a biodegradable polymer. Biodegradable poly(glycolide‐co‐caprolactone) (PGCL) copolymer was synthesized from glycolide and ϵ‐caprolactone in the presence of stannous octoate as catalyst. The copolymer was characterized by 1H‐NMR, gel permeation chromatography and differential scanning calorimetry. Scaffolds for tissue engineering applications were fabricated from PGCL copolymer using the solvent‐casting and particle‐leaching technique. The PGCL scaffolds produced in this fashion had open pore structures (average pore size = 250 μm) without the usual nonporous skin layer on external surfaces. Mechanical testing revealed that PGCL scaffolds were far more elastic than poly(lactic‐co‐glycolic acid) (PLGA) scaffolds fabricated using the same method. Tensile mechanical tests indicated that PGCL scaffolds could withstand an extension of 250% without cracking, which was much higher than withstood by PLGA scaffolds (10–15%). In addition, PGCL scaffolds achieved recoveries exceeding 96% at applied extensions of up to 230%, whereas PLGA scaffolds failed (cracked) at an applied strain of 20%. Dynamic mechanical tests showed that the permanent deformation of the PGCL scaffolds in a dry condition produced was less than 4% of the applied strain, when an elongation of 20% at a frequency of 1 Hz (1 cycle per second) was applied for 6 days. Moreover, PGCL scaffolds in a buffer solution also had permanent deformations less than 5% of the applied strain when an elongation of 10% at a frequency of 1 Hz was applied for 2 days. The usefulness of the PGCL scaffolds was demonstrated by engineering SM tissues in vivo. This study shows that the elastic PGCL scaffolds produced in this study could be used to engineer SM‐containing tissues (e.g. blood vessels and bladders) in mechanically dynamic environments. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 29–37, 2003
Surface modification of PLGA microspheres
Authors: Müller M. , Vörös J. , Csúcs G. , Walter E. , Danuser G. , Merkle H. P. , Spencer N. D. , Textor M. 
Published: June 2003

AbstractMicrospheres made of poly(lactic‐co‐glycolic acid) (PLGA) are biocompatible and biodegradable, rendering them a promising tool in the context of drug delivery. However, nonspecific adsorption of plasma proteins on PLGA micro‐ and nanospheres is a main limitation of drug targeting. Poly(L‐lysine)‐g‐poly(ethylene glycol) (PLL‐g‐PEG), physisorbed on flat metal oxide surfaces, has previously been shown to suppress protein adsorption drastically. The goal of our work was to characterize the efficiency of the protein repellent character of PLL‐g‐PEG on PLGA microspheres and to show the feasibility of introducing functional groups on the PLGA microspheres via functionalized PLL‐g‐PEG. To quantify the adsorbed amount of protein, a semiquantitative method that uses confocal laser scanning microscopy (CLSM) was applied. The first part of the experiment confirms the feasibility of introducing specific functional groups on PLL‐g‐PEG–coated PLGA microspheres. In the second part of the experiment, PLL‐g‐PEG–coated PLGA microspheres show a drastic decrease of adsorbed proteins by two orders of magnitude in comparison to uncoated PLGA microspheres. Low protein‐binding, functionalizable microspheres provide a fundamental basis for the design of drug delivery and biosensor systems. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 55–61, 2003
Noninvasive bone replacement with a new injectable calcium phosphate biomaterial
Authors: Gauthier O. , Khairoun I. , Bosco J. , Obadia L. , Bourges X. , Rau C. , Magne D. , Bouler J. M. , Aguado E. , Daculsi G. , Weiss P. 
Published: June 2003

AbstractThe use of injectable calcium phosphate (CaP) biomaterials in noninvasive surgery should provide efficient bone colonization and implantation. Two different kinds of injectable biomaterials are presently under development: ionic hydraulic bone cements that harden in vivo after injection, and an association of biphasic calcium phosphate (BCP) ceramic granules and a water‐soluble polymer vehicle (a technique particularly investigated by our group), providing an injectable CaP bone substitute (IBS). In our study, we compared these two approaches, using physicochemical characterizations and in vivo evaluations in light microscopy, scanning electron microscopy, and three‐dimensional microtomography with synchrotron technology. Three weeks after implantation in rabbit bone, both biomaterials showed perfect biocompatibility and bioactivity, but new bone formation and degradation of the biomaterial were significantly greater for BCP granules than for ionic cement. Newly formed bone developed, binding the BCP granules together, whereas new bone grew only on the surface of the cement, which remained dense, with no obvious degradation 3 weeks after implantation. This study confirms that BCP granules carried by a cellulosic polymer conserve bioactivity and are conducive to earlier and more extensive bone substitution than a carbonated‐hydroxyapatite bone cement. The presence of intergranular spaces in the BCP preparation, as shown on microtomography imaging, seems particularly favorable, allowing body fluids to reach each BCP granule immediately after implantation. Thus, the IBS functions as a completely interconnected ceramic with total open macroporosity. This new bone replacement approach should facilitate microinvasive bone surgery and local delivery of bone therapy agents. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 47–54, 2003
Osteogenic enrichment of bone‐marrow stromal cells with the use of flow chamber and type I collagen‐coated surface
Authors: Lan Cheng‐Wen , Wang Fung Fang , Wang Yng Jiin 
Published: June 2003

AbstractThe stromal cells of the bone marrow are able to attach to the surface and differentiate into cells with bone‐forming capability when stimulated with osteogenic supplements. In this study, we have employed a flow‐chamber device containing a collagen‐coated surface to enrich the potential osteoprogenitor cells from bone marrow stromal cells (BMSCs). The population of the cells attached to the collagen‐coated substratum is about twice that attached to the uncoated surface. In the flow chamber, almost all marrow cells attached on the untreated glass were flushed out at the shear stress of 1.10 dyne/cm2. On the other hand, 25% of the marrow cells remained attached to the collagen‐coated glass, even under the shear stress of 1.30 dyne/cm2. The collagen‐attached marrow cells exhibited similar, specific alkaline phosphatase activity compared with that of the cells attached to the uncoated dish in the early stage of culturing. Nevertheless, only the collagen‐attached marrow cells later expressed significant amounts of osteocalcin, which is a specific marker for osteoblast cells. Thus, we have successfully developed a protocol that uses a collagen‐coated surface efficiently in a flow chamber to enrich the osteogenic cells from the BMSCs. This provides a useful tool to obtain osteogenic cells from bone marrow for biologic and clinical applications. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 38–46, 2003
Monocyte/macrophage interactions with base and linear‐ and star‐like PEG‐modified PEG‐poly(acrylic acid) co‐polymers
Authors: Wagner Victoria E. , Bryers James D. 
Published: June 2003

AbstractPoly(ethylene glycol):poly(acrylate) PEG‐g‐PA co‐polymers were made that inhibited nonspecific protein and cellular adhesion. PEG‐g‐PA co‐polymers were then covalently modified with either cell adhesion peptides or fragments of antibodies to monocyte/macrophage integrin receptors (anti‐VLA4, anti‐β1, anti‐β2, and anti‐CD64) known to enhance macrophage adhesion and, perhaps, modulate their activation. Peptides were either directly conjugated to the base material or linked by way of PEO‐star tethers. Fragments of the antibody region containing the antigen‐binding site (Fab′ fragments) were coupled to other PEG‐g‐PA samples using the sulhydryl end groups on Fab′ fragments to amine‐bearing PEO stars. Macrophage adhesion rates, phagocytic response (oxidative burst), and cytokine expression were determined for each PEG‐g‐PA material. Luminol‐enhanced chemiluminescence was used as a semiquantitative indication of monocyte‐macrophage phagocytic activation (oxidative burst). Macrophage cytokine expression in response to control, base, and modified materials was determined by ELISAs for TNF‐α, IL‐1β, IL‐6, and IL‐8. Tissue culture poly(styrene) (TCPS)‐mediated the greatest number of adherent monocyte/macrophage cells relative to PEG‐g‐PA materials. Both YRGDS and YEILDV peptides, whether directly or indirectly (via StarPEO) conjugated to PEG‐g‐PA, increased adhesion versus controls. Fab′ fragments of all four antibodies also promoted enhanced adhesion versus controls. Fab′StarPEO materials presented two orders of magnitude fewer ligands per surface unit area than peptide star materials (108 vs. 1010), but were able to adhere similar numbers of cells. For surfaces presenting Fab′VLA‐4 or YEILDV, both of which may both bind to a cell's VLA‐4 receptor, the Star:VLA4 surface showed a greater number of adherent monocyte/macrophages. This result suggests that the Fab′ had a higher affinity to the cell receptor than a corresponding minimal peptide binding sequence. All materials exhibited low oxidative burst (luminescence counts per minute, LCPM) per cell DNA without the addition of exogenous stimuli (LCPM/DNA < 100). Directly conjugated peptide materials, poly(propylene) (PP), and TCPS showed the lowest levels of LCPM/DNA without the addition of exogenous stimulus (LCPM/DNA < 20). There was no correlation between LCPM/DNA ratios, with and without added LPS stimulus, versus the individual substrates. Monocyte/macrophages adherent to TCPS substrata showed the overall highest stimulatory potential in cytokine expression response to exogenous LPS, followed by PP > PEG‐g‐PA > StarPEO. Cells adherent to peptide‐modified materials and Fab′‐modified materials were overall less stimulated. The method of presenting the peptides (i.e., directly or via Star PEO) influenced the level of cytokine secreted by the adherent macrophage. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 62–78, 2003
Biomimetic nano‐apatite coating capable of promoting bone ingrowth
Authors: Li Panjian 
Published: June 2003

AbstractNano‐apatite coating closely mimicking bone mineral was grown directly on titanium soaked in an aqueous solution containing all major inorganic components present in the body, mainly, HCO, Ca2+, HPO, and Mg2+ ions. The removal of HCO3− ions from the solution in the form of CO2 resulted in the increase of solution pH. As a consequence of this reaction, the nano‐apatite coating was formed on the surface of titanium with composition and structure equivalent to those of bone mineral. The biomimetic nano‐apatite was demonstrated to be capable of conducting bone formation and promoting direct bone apposition. This bioactive coating also affected the behavior of human osteoblasts as indicated by their morphologies observed in cell culture study. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 79–85, 2003
In vivo biocompatibility evaluation of cellulose macrocapsules for islet immunoisolation: Implications of low molecular weight cut‐off
Authors: Risbud Makarand V. , Bhargava Shobha , Bhonde Ramesh R. 
Published: June 2003

AbstractEarlier we showed the in vitro suitability of cellulose molecular dialysis membrane of low cut‐off for islet immunoisolation. Using a syngenic islet transplantation model, here we report the in vivo biocompatibility status and discuss implications of the low molecular weight cut‐off of this membrane. Streptozotocin diabetic mice were transplanted ip with islet grafts in cellulose macrocapsules and monitored for 6 weeks for their blood glucose profiles. Membrane biocompatibility was evaluated by assessing islet graft morphometry, viability, functionality, and tissue reaction against the capsules. Animals (n = 10) attained normoglycemia after 1 week of transplantation and remained nondiabetic throughout a follow‐up of 6 weeks. Animals subjected to a glucose tolerance test at the end of the study showed delayed glycemic control, indicating a delayed insulin response. Grafts retrieved after the 15th day and after 6 weeks showed viable islets, between 70–80% and ≈40%, respectively, with morphometric parameters similar to freshly isolated islets. Graft retrievals resulted in a recurrence of hyperglycemia, indicating a functional tissue mass. A mild tissue reaction with a few immunocytes and a very thin fibrous capsular reaction were seen against the macrocapsule membrane. This study points out the in vivo suitability of cellulose membrane for islet immunoisolation. However, applicability of this membrane is limited due to its low cut‐off value. Membranes with a higher molecular weight cut‐off may render better glycemic control and higher graft viability. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 86–92, 2003
Bioactivity of gel–glass powders in the CaO‐SiO2 system: A comparison with ternary (CaO‐P2P5‐SiO2) and quaternary glasses (SiO2‐CaO‐P2O5‐Na2O)
Authors: Saravanapavan Priya , Jones Julian R. , Pryce Russell S. , Hench Larry L. 
Published: June 2003

AbstractBioactive glasses react chemically with body fluids in a manner that is compatible with the repair processes of the tissues. This results in the formation of an interfacial bond between the glasses and living tissue. Bioactive glasses also stimulate bone–cell proliferation. This behavior is dependent on the chemical composition as well as the surface texture of the glasses. It has been recently reported that gel‐derived monolith specimens in the binary SiO2 CaO are bioactive over a similar molar range of SiO2 content as the previously studied ternary CaO‐P2O5‐SiO2 system. In this report, the preparation and bioactivity of the binary gel–glass powder with 70 mol % SiO2 is discussed and its bioactivity is compared with the melt‐derived 45S5 (quaternary) Bioglass® and sol–gel‐derived 58S (ternary) bioactive gel–glass compositions. Dissolution kinetic parameters K1 and K2 were also computed based on the silicon release for all glass powders. It was shown that the simple two‐component SiO2‐CaO gel–glass powder is bioactive with comparable dissolution rates as the clinically used melt‐derived 45S5 Bioglass® powder and extensively studied sol–gel‐derived 58S gel–glass powder. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 110–119, 2003
In vivo degradation characteristics of poly(glycerol sebacate)
Authors: Wang Yadong , Kim Yu Mi , Langer Robert 
Published: June 2003

AbstractWe have developed a series of biodegradable elastomers, poly(glycerol sebacate) (PGS), based on glycerol and sebacic acid. The polymers are potentially useful in soft tissue regeneration and engineering. To evaluate the performance of PGS in a physiological environment, we compared their degradation profiles with poly(DL‐lactide‐co‐glycolide) (50:50, carboxyl ended, Mw 15,000) in vivo. Among the parameters examined are changes in weight and mechanical strength with time, implant geometry, surface characteristics, and degree of swelling. Unlike poly(DL‐lactide‐co‐glycolide), PGS primarily degrades by surface erosion, which gives a linear degradation profile of mass, preservation of geometry and intact surface, and retention of mechanical strength. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 192–197, 2003
Fatigue crack propagation path across the dentinoenamel junction complex in human teeth
Authors: Dong X. D. , Ruse N. D. 
Published: June 2003

AbstractThe human tooth structures should be understood clearly to improve clinically used restorative materials. The dentinoenamel junction (DEJ) plays a key role in resisting crack propagation in teeth. The aim of this study was to determine the fracture toughness of the enamel‐DEJ‐dentin complex and to investigate the influence of the DEJ on the fatigue crack propagation path across it by characterizing fatigue‐fractured enamel‐DEJ‐dentin complexes using optical and scanning electron microscopy. The results of this study showed that the fracture toughness of the enamel‐DEJ‐dentin complex was 1.50 ± 0.28 Mpa·m1/2. Based on the results of this investigation, it was concluded that the DEJ complex played a critical role in resisting crack propagation from enamel into dentin. The DEJ complex is, approximately, a 100 to 150 μm broad region at the interface between enamel and dentin. The toughening mechanism of the DEJ complex may be explained by the fact that crack paths were deflected as cracks propagated across it. Understanding the mechanism of crack deflection could help in improving dentin‐composite as well as ceramic‐cement interfacial qualities with the aim to decrease the risk of clinical failure of restorations. Both can be viewed as being composed from a layer of material of high strength and hardness bonded to a softer but tougher substratum (dentin). The bonding agent or the luting cement layer may play the critical role of the DEJ in improving the strength of these restorations in clinical situations. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 103–109, 2003
Role of elastin in pathologic calcification of xenograft heart valves
Authors: Bailey Michael T. , Pillarisetti Swadeep , Xiao Hui , Vyavahare Naren R. 
Published: June 2003

AbstractBioprosthetic heart valves fabricated from glutaraldehyde crosslinked porcine aortic valves often fail because of calcific degeneration. Calcification occurs in both cusp and aortic wall portions of bioprosthetic heart valves. The purpose of this study was to discern the role of different aortic wall components in the calcification process. Thus, we selectively extracted cells and other extracellular matrix proteins from porcine aorta using trypsin/DNase/RNase, cyanogen bromide (CNBr), and sodium hydroxide (NaOH) treatments and subdermally implanted these pretreated aortas in young rats. Total DNA and phospholipid data showed complete removal of cells by CNBr and NaOH treatments, whereas trypsin/DNase/RNase treatment was effective in removing DNA but not phospholipids. As shown by amino acid data and Masson's trichrome staining, collagen was removed in CNBr and NaOH treatments. Control fresh porcine aorta calcified significantly after 21 days of implantation (Ca 26.4 ± 2.4 μg/mg). Removal of cells and collagen from the aorta by CNBr treatment did not lead to a statistically significant reduction in aortic calcification (Ca 20.8 ± 3.0 μg/mg). Moreover, partial degradation of elastin fibers caused by NaOH (during extraction) and trypsin treatment (after implantation) of the aorta significantly increased elastin‐oriented calcification (Ca 94.4 ± 9.3 and 58.4 ± 4.6 μg/mg, respectively). Our results indicate that the elastin component of the aorta may undergo independent calcification irrespective of devitalized cell‐mediated calcification observed in glutaraldehyde crosslinked aortas. Our results also demonstrate the importance of studying elastin‐oriented calcification in decellularized elastin‐rich aortic matrices currently used in tissue‐engineering applications. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 93–102, 2003