bluuebunny/crossref_metadata_2025 huggingface dataset:
Biomimetic surfactant polymers designed for shear‐stable endothelialization on biomaterials
Authors: Sagnella Sharon , Kligman Faina , Marchant Roger E. , Kottke‐Marchant Kandice
Published: November 2003

We have developed a series of “extracellular matrix (ECM)‐like” biomimetic surfactant polymers to improve endothelial cell adhesion and growth on vascular biomaterials. These polymers provide a single‐step procedure for modifying the surface of existing biomaterials and consist of a poly(vinyl amine) (PVAm) backbone with varying ratios of cell‐binding peptide (RGD) to carbohydrate (maltose), ranging from 100% RGD:0% maltose to 50% RGD:50% maltose. Three biomimetic surfaces, as well as a fibronectin (FN)‐coated glass surface were seeded at confluence with human pulmonary artery endothelial cells (HPAECs) and exposed to shear stresses ranging from 0–40.6 dyn/cm2 for periods of 2 h and 6 h. Surfaces were examined for HPAEC coverage and cytoskeletal arrangement as a function of time and shear stress. In general, after 6 h of shear exposure, EC retention on 100% RGD > FN > 75% RGD > 50% RGD. The 100% RGD surface maintained more than 50% of its initial EC monolayer at low to moderate shear stresses whereas all other surfaces dropped to ≈40% or less in the same shear stress range. The most stable surface, 100% RGD, showed a significant increase in cytoskeletal organization at all shear stresses greater than 2.5 dyn/cm2. In contrast, there was no real change in cytoskeletal organization on the FN surface, and there was a decrease on the 75% RGD surface over time. These results indicate that increasing surface peptide density can control EC shear stability. Furthermore, improved shear stability increases with increasing peptide density and is related to the EC's ability to reorganize its cytoskeleton. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 689–701, 2003
Ex ova chick chorioallantoic membrane as a novel model for evaluation of tissue responses to biomaterials and implants
Authors: Klueh Ulrike , Dorsky David I. , Moussy Francis , Kreutzer Don L.
Published: November 2003

One of the major obstacles in developing rationale strategies to control inflammation and fibrosis surrounding implants is the lack of a simple and inexpensive in vivo model to screen tissue reactions to various biomaterials and implants. To begin to fill this gap, we have developed an ex ova model of the chick embryo chorioallantoic membrane (CAM) for testing of tissue reaction to biomaterials and implants. For these studies, we evaluated tissue reactions (inflammation and fibrosis) to two commonly used biomaterials (nylon and silastic) grossly and histologically in the ex ova CAM. Nylon mesh was incorporated within the CAM tissue 4 days postplacement. After 8 days postplacement, the nylon mesh was totally incorporated into the CAM. Histologically, little or no inflammation was seen associated with the incorporated nylon mesh at any time point. In the case of silastic tubing, significant incorporation of the CAM was seen grossly by 1–2 days postplacement. Incorporation of the tubing continued at day 8 postplacement of the silastic tubing, with ingrowth of the CAM into the lumen of the tubing. Histological evaluation of CAMs indicated that no significant tissue reactions (inflammation or fibrosis) occurred in the CAM tissue surrounding the silastic tubing or in the CAM tissue and vasculature that had grown into the silastic tubing. To our knowledge, this report represents the first investigation of the usage of the ex ova CAM model, a shell‐less chick embryo model (ex ova), as an in vivo model to test the tissue reactions to biomaterials and implants. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 838–843, 2003
The effect of irradiation, annealing temperature, and artificial aging on the oxidation, mechanical properties, and fracture mechanisms of UHMWPE
Authors: Luisetto Yannick , Wesslen Bengt , Maurer Frans , Lidgren Lars
Published: November 2003

UHMWPE crosslinked using Gamma radiation is believed to have improved wear properties, and this has been extensively studied during the past 10 years. Mechanical properties, oxidation, and wear properties of UHMWPE materials subjected to various thermal treatments have been investigated immediately after irradiation as well as after several years of aging. Nevertheless, the relationship between all these parameters is not yet fully understood. The aim of this study was to investigate the relationship between the thermal treatments that could be applied to irradiated UHMWPE [lower (γ60) or higher (γ150) than 140°C, the melting temperature of the polymer] and the mechanical properties, the oxidation and the fracture behavior of the material. The effect of artificial aging on these properties was also investigated. This study concludes that immediately after the annealing, the mechanical properties (UTS and ϵ) of the irradiated and annealed material are improved compared with those of nonirradiated material. Although nonirradiated material has higher fracture toughness than irradiated and annealed materials, the materials break according to the same mechanism of fracture. After aging, no changes could be observed in any of the measured properties for nonirradiated material. On the other hand, important changes could be seen in both irradiated and annealed material after aging. Both UTS and ϵ decreased, much more so in the case of γ60. Furthermore, the aging induced a subsurface peak of oxidation in both irradiated and annealed materials, twice as intense for γ60 than for γ150. The mechanism of fracture of these materials changed drastically after aging, probably due to the presence of the oxidation peak, which seems to occur at a location where cracks initiate easily compared with the nonoxidized bulk of the material. In the case of γ60, it seems clear that a correlation between mechanical property, oxidation, and fracture mechanism exists. Such a relationship could not be found for γ150. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 908–917, 2003
Novel method of preparing acellular cardiovascular grafts by decellularization with poly(ethylene glycol)
Authors: Uchimura Eiichiro , Sawa Yoshiki , Taketani Satoshi , Yamanaka Yuka , Hara Masayuki , Matsuda Hikaru , Miyake Jun
Published: November 2003

We have developed a new method of preparing acellular vascular grafts. Cellular components, including cell membranes and proteins in cytosol, were efficiently extracted from the vessels in a concentrated aqueous solution of poly(ethylene glycol), an amphiphilic biocompatible polymer. The residual DNA was digested by deoxyribonuclease I treatment after extraction with poly(ethylene glycol). The two‐step extraction process proved quite effective at removing the cellular components while causing little damage to the extracellular matrices. We did not use any detergent that would damage the extracellular matrices. Therefore, vascular endothelial cells grew well on the acellular vessels after recellularization, promising longi‐patent cardiovascular grafts. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 834–837, 2003
Colonization of organoapatite–titanium mesh by preosteoblastic cells
Authors: Spoerke Erik D. , Stupp Samuel I.
Published: November 2003

Titanium (Ti) and its alloys continue to serve as successful implant materials for skeletal repair because of their physical properties and biocompatibility. This study investigates the influence of organoapatite (OA), grown directly onto an L‐shaped Ti mesh, on preosteoblastic cellular colonization. Unseeded mesh samples were placed on subconfluent layers of MC3T3‐E1 murine calvaria cells and cultured for up to 2 weeks. Cells demonstrated accelerated colonization of the three‐dimensional OA–Ti mesh substrates over bare Ti controls. Cells also showed significantly increased proliferation on the OA–Ti mesh over bare Ti controls. Cellular differentiation, measured by alkaline phosphatase and osteocalcin expression, was observed at late stages of the experiment with no notable differences between OA–Ti mesh and bare Ti controls. These results suggest that OA grown onto porous Ti substrates is capable of inducing accelerated colonization of unseeded implant structures by osteogenic cells. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 960–969, 2003
NH3/O2 mixed gas plasmas alter the interaction of blood components with stainless steel
Authors: Chen Meng , Zamora Paul O. , Peña Louis , Som Prantika , Osaki Shigemasa
Published: November 2003

Stainless steel treated with a mixed gas plasma of NH3 plus O2 had chemical and biologic characteristics distinct from untreated stainless steel or stainless steel treated with NH3 or O2 plasmas used separately. NH3/O2 plasmas deposited nitrogen as both −CN (organic) and −NO (nitrate, nitrite)—materials not found on untreated stainless steel—and the contact angle changed from 44° to 23°. Treatment of stainless steel (and titanium) resulted in surfaces with enhanced resistance to platelet and leukocyte attachment. A gas plasma of N2O/O2 also was found to reduce platelet and leukocyte attachment, suggesting that these properties may be common to surfaces coated with oxynitrites (nitrides). Upon subcutaneous implantation, no inflammation, hemolysis, or untoward thrombosis was noted in the tissue surrounding the wafers treated with the NH3/O2 plasmas, although the cellular density was considerably reduced by 2 weeks after implant. Collectively, the results suggest that NH3/O2 plasmas impart a unique character to stainless steel that may be useful in the construction of medical devices. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 994–1000, 2003
Effect of hydrogen peroxide on titanium surfaces: In situ imaging and step‐polarization impedance spectroscopy of commercially pure titanium and titanium, 6‐aluminum, 4‐vanadium
Authors: Bearinger Jane P. , Orme Christine A. , Gilbert Jeremy L.
Published: November 2003

To analyze titanium's response to representative surgical wound environments, a study was conducted on commercially pure titanium (CPTi) and titanium, 6‐aluminum, 4‐vanadium (Ti‐6Al‐4V) exposed to phosphate‐buffered saline (PBS) with 30 mM of hydrogen peroxide (H2O2) added. The study was characterized by simultaneous electrochemical atomic force microscopy (EC AFM) and step‐polarization impedance spectroscopy (SPIS). Surfaces were covered with protective oxide domes that indicated topography changes with potential and time of immersion. Less oxide dome coarsening was noted on surfaces treated with PBS containing H2O2 than on surfaces exposed to pure PBS. Electrical data deduced from current transients collected while stepping voltage between 0 V and 1 V indicated that charge transfer in hydrogen peroxide solutions was an order of magnitude larger than it was in pure PBS. Oxide (early) resistances of CPTi samples were higher than were Ti‐6Al‐4V oxide resistances in both types of solutions, but CPTi oxide resistance was lower in the hydrogen peroxide solution compared to pure PBS. Capacitance data suggest that CPTi oxide films thicken in hydrogen peroxide solution more than they do in pure PBS. Differences in electrical properties between CPTi and Ti‐6Al‐4V surfaces suggest that CPTi, but not Ti‐6Al‐4V, has catalytic activity on H2O2 and that the catalytic activity of CPTi oxide affects its ability to grow TiO2. Differences in electrical properties are related to catalytic and oxidative mechanisms that take place directly on the titanium oxide surface and in wound environments. The study provides a foundation and theoretic basis for the porous oxide model on commercially pure titanium exposed to hydrogen peroxide. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 702–712, 2003
In vivo behavior of poly(1,3‐trimethylene carbonate) and copolymers of 1,3‐trimethylene carbonate with D,L‐lactide or ϵ‐caprolactone: Degradation and tissue response
Authors: Pêgo A. P. , Van Luyn M. J. A. , Brouwer L. A. , van Wachem P. B. , Poot A. A. , Grijpma D. W. , Feijen J.
Published: November 2003

The degradation and the tissue response evoked by poly(1,3‐trimethylene carbonate) [poly(TMC)] and copolymers of TMC with either 52 mol % D,L‐lactide (DLLA) or 89 mol % ϵ‐caprolactone (CL) were evaluated in vivo by subcutaneous implantation of polymer films in rats for periods up to one year. Poly(TMC) specimens were extensively degraded after 3 weeks and, as confirmed by histology, totally resorbed in less than a year. A fast linear decrease in thickness and mass without a change in molecular weight was observed. Initially an acute sterile inflammatory tissue reaction, caused by the implantation procedure, was observed, followed by a mild macrophage‐mediated foreign body reaction that lasted during the resorption period of the polymer. It is concluded that in vivo, poly(TMC) is degraded via surface erosion involving cellular‐mediated processes. The degradation of the copolymers was slower than that of poly(TMC), taking place via autocatalyzed bulk hydrolysis, preferentially of ester bonds. The TMC‐DLLA copolymer degraded 20 times faster than the TMC‐CL one. In both cases, the tissue reaction upon implantation resembled a sterile inflammatory reaction followed by a foreign body reaction that led to the polymer encapsulation. Significant mass loss was only observed for the TMC‐DLLA copolymer, which underwent 96% mass loss in 1 year. When extensive mass loss started, a mild‐to‐moderate secondary foreign body reaction, related to clearance of the polymer fragments, was triggered. The results presented in this study demonstrate that poly(TMC) and both TMC copolymers are biodegradable and biocompatible materials, making these polymers attractive for the preparation of short‐ and long‐term degradable devices for soft tissue engineering. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 1044–1054, 2003
Bonding strength of the apatite layer formed on glass‐ceramic apatite‐wollastonite–polyethylene composites
Authors: Juhasz J. A. , Best S. M. , Kawashita M. , Miyata N. , Kokubo T. , Nakamura T. , Bonfield W.
Published: November 2003

Bioactive glass‐ceramic apatite‐wollastonite (A‐W) has been incorporated into polyethylene in particulate form to create new bioactive composites for potential maxillofacial applications. The effects of varying the volume fraction of glass‐ceramic A‐W filler and the glass‐ceramic A‐W particle size were investigated by measuring the bonding strength of the bonelike apatite layer formed on the surface of glass‐ceramic A‐W–polyethylene composites. The bonding strength was evaluated via a modified ASTM C‐333 standard in which a tensile stress was applied to the substrate and the strength of the bioactive layer was compared with that formed on commercially available hydroxyapatite–polyethylene composite samples, HAPEX™. The composites demonstrated greater bonding strength with increased filler content and reduced filler particle size (maximum 6.9 ± 0.5 MPa) and a marginally greater bonding strength as compared with HAPEX™ (2.8 ± 0.5 MPa), when glass‐ceramic A‐W–polyethylene composite samples with the same filler content were tested. The higher bonding strength of the apatite layer formed on the A‐W–polyethylene composite samples suggests that, in addition to maxillofacial applications, these composites might also be utilized in applications involving higher levels of load bearing. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 952–959, 2003
Preparation and development of anti‐chitosan antibodies
Authors: Sorlier Pierre , Hartmann Daniel J. , Denuzière Anne , Viton Christophe , Domard Alain
Published: November 2003

Polyclonal antibodies directed against chitosan were produced using several immunogens, prepared by binding the polymer according to two ways (covalent and electrostatic) with a protein (bovine serum albumin or hemocyanin). It appeared that the presence of a carrier protein linked to chitosan was necessary to enhance the immune response and to obtain antibodies in a stable and reproducible way. Direct and inhibition enzyme‐linked immunosorbent assay experiments were performed to assess the affinity and the specificity of the antibodies. The interactions of these antibodies with modified chitosans showed no influence of the degree of polymerization of the polymer in the range studied (from 24 to 2261), by contrast with the degree of acetylation. The affinity decreased when the degree of acetylation increased. Absence of cross‐reactivity with glycosaminoglycans was observed whatever the antibody. The cationicity of the amine function along the polymer chains may have a role in the immunological recognition of the chitosan structure. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 766–774, 2003
Quantitative assessment of collagen assembly by live cells
Authors: Johnson Chad , Galis Zorina S.
Published: November 2003

Changes in supramolecular assembly of matrix, specifically collagen, have important functional consequences, especially for tissues requiring high mechanical strength. Thus modulation of collagen assembly could be used as a therapeutic intervention or to control the development of tissue‐engineered constructs containing natural matrix. Quantitative methods that monitor such effects currently are lacking. Using live cultured cells, we developed a convenient way either to visualize by fluorescence microscopy or to measure directly, using a high throughput fluorescence assay, the supramolecular assembly of FITC‐labeled collagen monomers. The wide applicability of this assay was confirmed by testing the assay using two major collagen sources, rat tail and bovine skin, and vascular smooth muscle cells from two different origins, mouse aorta and human saphenous vein. We further determined that treatments that interfere with the function of the cytoskeleton modulate collagen assembly. Use of positive and negative regulators of lysyl‐oxidase indicated that while the assay does not require active production of endogenous collagen, it can be used to monitor the incorporation of such de novo synthesized collagen into labeled fibrils. Thus we have designed a novel quantitative assay that can monitor assembly of exogenous and endogenous collagen by live cells and reveal the effects of various interventions upon this process. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 775–784, 2003
Mechanical properties and Young's modulus of plasma‐sprayed hydroxyapatite coating on Ti substrate in simulated body fluid
Authors: Yang Y. C. , Chang Edward , Lee S. Y.
Published: November 2003

This study evaluated the Young's modulus, residual stress and strain, bonding strength, and microstructure of the plasma‐sprayed hydroxyapatite coating (HAC) on Ti6Al4V substrate with and without immersion in Hank's balanced salt solution (HBSS). The purpose was to explore the possible correlation of HAC durability and mechanical properties of the coating. The results show that the residual stress and strain, Young's modulus, and bonding strength of the HAC after immersion in HBSS are substantially decreased. The decayed Young's modulus and mechanical properties of HACs are accounted for by the degraded interlamellar or cohesive bonding in the coating due to the increased porosity after immersion that weakens the bonding strength of coating and substrate system. The biologic implications of the research are discussed in detail. This study contributes to the arguments that the method to alleviate the dissolution of HAC will increase the bonding strength of the coating system after immersion, which together with the controlled residual stress and strain in the coating might promote the long‐term stability of the HA‐coated implant. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 886–899, 2003
Preparation, degradation, and calcification of biodegradable polyurethane foams for bone graft substitutes
Authors: Gorna Katarzyna , Gogolewski Sylwester
Published: November 2003

Autogenous cancellous bone graft is used to heal critical‐size segmental long bone defects and defects in the maxillofacial skeleton. Harvesting of bone graft is traumatic, causes morbidity of the donor site, and often results in complications. Thus, there is a need for new biologically functional bone graft substitutes that, instead of autogenous bone graft, could be used to facilitate bone regeneration in critical‐size defects. Porous biodegradable elastomeric polyurethane scaffolds combined with the patient's own bone marrow could potentially be such bone substitutes. The elastomeric bone substitute prevents shear forces at the interface between bone and rigid, e.g., ceramic bone substitutes and establishes an intimate contact with the native bone ends, thus facilitating the proliferation of osteogenic cells and bone regeneration. Crosslinked 3D biodegradable polyurethane scaffolds (foams) with controlled hydrophilicity for bone graft substitutes were synthesized from biocompatible reactants. The scaffolds had hydrophilic‐to‐hydrophobic content ratios of 70:30, 50:50, and 30:70. The reactants used were hexamethylene diisocyanate, poly(ethylene oxide) diol (MW = 600) (hydrophilic component), and poly(ϵ‐caprolactone) diol (Mw = 2000), amine‐based polyol (Mw = 515) or sucrose‐based polyol (Mw = 445) (hydrophobic component), water as the chain extender and foaming agent, and stannous octoate, dibutyltin dilaurate, ferric acetylacetonate, and zinc octoate as catalysts. Citric acid was used as a calcium complexing agent, calcium carbonate, glycerol phosphate calcium salt, and hydroxyapatite were used as inorganic fillers, and lecithin or solutions of vitamin D3 were used as surfactants. The scaffolds had an open‐pore structure with pores whose size and geometry depended on the material's chemical composition. The compressive strengths of the scaffolds were in the range of 4–340 kPa and the compressive moduli in the range of 9–1960 kPa, the values of which increased with increasing content of polycaprolactone. Of the two materials with the same amount of polycaprolactone the compressive strengths and moduli were higher for the one containing inorganic fillers. The scaffolds absorbed water and underwent controlled degradation in vitro. The amount of absorbed water and susceptibility to degradation increased with the increasing content of the polyethylene oxide segment in the polymer chain and the presence in the material of calcium complexing moiety. All polyurethane scaffolds induced the deposition of calcium phosphate crystals, the structure and calcium:phosphorus atomic ratio of which depended on the chemical composition of the polyurethane and varied from 1.52–2.0. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 813–827, 2003
Dimensional changes in acid‐demineralized dentin matrices following the use of HEMA–water versus HEMA–alcohol primers
Authors: Eddleston C. L. , Hindle A. R. , Agee K. A. , Carvalho R. M. , Tay F. R. , Rueggeberg F. A. , Pashley D. H.
Published: November 2003

Although dried acid‐etched dentin can be reexpanded by hydroxyethyl methacrylate (HEMA)/water primers, the primed dentin collapses when the water is evaporated. Experimental HEMA/alcohol primers should stiffen the matrix and permit less shrinkage when the solvent is evaporated. The purpose of this study was to test the hypotheses that matrix shrinkage induced by solvent evaporation from HEMA primers is inversely related to solvent‐induced matrix stiffness. Dentine discs were prepared from midcoronal dentine of unerupted human third molars. After demineralization in 37% phosphoric acid, the specimens were placed in the well of a linear variable differential transformer instrument, which measures changes in the matrix height and stiffness by load displacement after the application of weights. This was done in their hydrated state after water had been applied, after drying with dry nitrogen gas, and after the application of 35 vol % HEMA–water, HEMA–methanol, HEMA–ethanol, or HEMA–propanol primers. The degree of reexpansion after the application of the primers to the dentine in the dried state was found to be highest using the HEMA–water primer, followed by HEMA–methanol and HEMA–ethanol, with the HEMA–propanol primer producing no expansion. However, when the solvents were evaporated the HEMA–water‐treated specimens shrank the most, the HEMA–ethanol‐treated specimens shrank an intermediate amount, and the HEMA–methanol‐treated specimens shrank the least. The net result of expansion minus shrinkage produced by evaporation determines how much HEMA remains in the hybrid layer just prior to polymerization. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 900–907, 2003
Material‐induced tissue factor expression but not CD11b upregulation depends on the presence of platelets
Authors: Gorbet M. B. , Sefton M. V.
Published: November 2003

Biomaterials activate leukocytes as well as platelets when exposed to blood. One feature of leukocyte activation at least at times beyond a few hours is tissue factor expression, contributing to a procoagulant state. We show here that platelet activation and specifically platelet–monocyte aggregate formation appears to be a precondition for tissue factor expression. Material‐induced Tissue Factor (TF) expression by isolated leukocytes (6 × 106 cells/mL) resuspended in increasing concentrations of platelets in plasma was elevated when the platelet concentration was 50 × 106 platelets/mL or more; at lower platelet concentrations (1–25 × 106 · cells/mL) the TF expression remained at background levels. On the other hand, significant CD11b upregulation was observed on leukocytes, in bulk and adherent to beads, at all platelet concentrations. This platelet effect on material‐induced TF expression appeared to be mediated by the formation of platelet–monocyte aggregates. Anti‐P‐selectin, which blocked the association between platelets and leukocytes, reduced monocyte adhesion and material‐induced TF expression for bulk monocytes. Anti‐GPIIb/IIIa, a GPIIb/IIIa platelet antagonist, also reduced monocyte adhesion and material‐induced TF expression in the bulk, most likely due to its inhibiting effect on the formation of platelet–monocyte aggregates, secondary to platelet activation. However, the antibody‐associated reductions for bulk leukocytes (mainly neutrophils) were small and incomplete. Similar levels of TF expression, in the bulk, were observed with both polystyrene (PS), a strong platelet activator, and polyethylene glycol‐modified PEG (PS‐PEG), a mild platelet activator. The role of platelets in material‐induced TF expression appears to be mediated in part via the formation of platelet–monocyte aggregates, although other mechanisms are likely also involved. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 792–800, 2003
Increased osteoblast adhesion on titanium‐coated hydroxylapatite that forms CaTiO3
Authors: Webster Thomas J. , Ergun Celaletdin , Doremus Robert H. , Lanford William A.
Published: November 2003

CaTiO3 is a strong candidate to form at the interface between hydroxylapatite (HA) and titanium implants during many coating procedures. However, few studies have compared the cytocompatibility properties of CaTiO3 to HA pertinent for bone–cell function. For this reason, the objective of the present in vitro study was to determine the ability of bone‐forming cells (osteoblasts) to adhere on titanium coated with HA that resulted in the formation of CaTiO3. To accomplish the formation of CaTiO3, titanium was coated on HA discs and annealed either under air or a N2+H2 environment. Materials were characterized by X‐ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), and atomic force microscopy (AFM). These characterization techniques demonstrated the formation of a nanometer rough CaTiO3 layer as a consequence of interactions between HA and titanium during coating conditions. Results from cytocompatibility tests revealed increased osteoblast adhesion on materials that contained CaTiO3 compared to both pure HA and uncoated titanium. The greatest osteoblast adhesion was observed on titanium‐coated HA annealed under air conditions. Because adhesion is a crucial prerequisite to subsequent functions of osteoblasts (such as the deposition of calcium containing mineral), the present in vitro results imply that orthopedic coatings that form CaTiO3 could increase osseointegration with juxtaposed bone needed for increased implant efficacy. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 975–980, 2003
The effect of silica‐containing calcium‐phosphate particles on human osteoblasts in vitro
Authors: Phan Phong V. , Grzanna Mark , Chu James , Polotsky Anna , El‐Ghannam Ahmed , Van Heerden David , Hungerford David S. , Frondoza Carmelita G.
Published: November 2003

There is an ongoing need for more effective and less costly bone substitutes. It has previously been proposed that silica‐containing bioactive glass would be more effective as a bone repair material because of its physiochemical properties. Three newly synthesized silica‐containing bioactive glass formulations, HA‐31 (25%), HA‐11 (50%), and HA‐13 (75%), were tested as biocompatible substrates for the continued proliferation and phenotype expression of human bone cells in vitro. Two currently available bioactive glasses (BioGlass®, Hydroxyapatite) served as comparisons. The biocompatibility of these bioglasses, as well as their osteoconductive properties, was assessed by employing primary cultures of human osteoblasts and human synoviocytes for 4 days. The results obtained demonstrated that the three new bioglasses enhanced the proliferative response of osteoblasts compared with osteoblasts cultured alone. Reverse Transcription Polymerase Chain Reaction (RT‐PCR) analysis indicated that osteoblasts retained their phenotypic expression by continued expression of collagen type I and alkaline phosphatase. The newly synthesized preparations of silica‐containing bioactive glass did not induce stimulation of proinflammatory markers iNOS and IL‐1β in synoviocytes. In conclusion, the newly synthesized silica‐containing bioactive glasses are biocompatible substrate for bone‐forming osteoblasts. However, the formulations tested did not show significant advantage over the currently available bioactive glasses in vitro. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 1001–1008, 2003
Metal ions alter lipopolysaccharide‐induced NFκB binding in monocytes
Authors: Lewis J. B. , Wataha J. C. , Randol T. M. , McCloud V. V. , Lockwood P. E.
Published: November 2003

Metals are components of a variety of biomaterials used in orthopedic and dental appliances; however, their biocompatibility with the surrounding tissues is not completely understood. Monocytes are important immune cells that respond to inflammatory stimuli by rapidly producing a variety of inflammatory proteins. Regulation of this response often involves activation of the transcription factor NFκB. The current study was designed to determine whether monocyte activation of NFκB in response to bacterial lipopolysaccharide (LPS) is affected by pretreatment with metal ions. Concentrations of metal ions that affected cell number after 24 h of exposure were first determined. Then THP‐1 human monocytes were cultured for 2 h in media containing metal ions at concentrations below levels that altered cell growth. Parallel cultures were treated with 10 μg/mL Escherichia coli LPS, and all samples were cultured an additional 2 h. Nuclear proteins were extracted and normalized amounts were incubated with [32P]‐end‐labeled NFκB consensus oligonucleotide. NFκB–DNA complexes were identified and quantified by electrophoretic mobility shift analysis. The extent of NFκB–DNA complex formation after metal ion pretreatment with or without LPS induction was compared to no treatment or LPS‐only treated controls. Finally, LPS‐induced IL1β secretion was measured from palladium‐treated and control cells. Concentrations were identified for each metal ion (Ag+, Co2+, Cu2+, Hg2+, Ni2+, and Pd2+) that did not reduce cell number after 24 h of exposure (ranging from 5 μM for Ag+ and Hg2+ to 200 μM for Ni2+). Exposures of 2 h at these concentrations did not alter cell morphology, staining with trypan blue, or cell number. LPS exposure had no effect on cell number with or without metal ions after 2 h. When metal treatment alone was assessed, none of the metal ions had a significant effect on NFκB–DNA binding. However, pretreatment with Co2+, Ni2+, Ag1+, Hg2+, and Pd2+ significantly decreased NFκB–DNA binding by 40–70% versus LPS alone. Only Cu2+ had no effect on LPS‐induced NFκB–DNA complex formation. Pd2+ lowered, but did not abolish, IL1β secretion at concentrations comparable to those that altered NFκB–DNA binding. These results suggest that many commonly used metals alter monocyte function at concentrations that are not overtly toxic, and that protein levels controlled in part by NFκB also may be altered. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 868–875, 2003
Porosity of porcine bladder acellular matrix: Impact of ACM thickness
Authors: Farhat Walid , Chen Jun , Erdeljan Petar , Shemtov Oren , Courtman David , Khoury Antoine , Yeger Herman
Published: November 2003

The objectives of this study are to examine the porosity of bladder acellular matrix (ACM) using deionized (DI) water as the model fluid and dextran as the indicator macromolecule, and to correlate the porosity to the ACM thickness. Porcine urinary bladders from pigs weighing 20–50 kg were sequentially extracted in detergent containing solutions, and to modify the ACM thickness, stretched bladders were acellularized in the same manner. Luminal and abluminal ACM specimens were subjected to fixed static DI water pressure (10 cm); and water passing through the specimens was collected at specific time interval. While for the macromolecule porosity testing, the diffusion rate and direction of 10,000 MW fluoroescein‐labeled dextrans across the ACM specimens mounted in Ussing's chambers were measured. Both experiments were repeated on the thin stretched ACM. In both ACM types, the fluid porosity in both directions did not decrease with increased test duration (3 h); in addition, the abluminal surface was more porous to fluid than the luminal surface. On the other hand, when comparing thin to thick ACM, the porosity in either direction was higher in the thick ACM. Macromolecule porosity, as measured by absorbance, was higher for the abluminal thick ACM than the luminal side, but this characteristic was reversed in the thin ACM. Comparing thin to thick ACM, the luminal side in the thin ACM was more porous to dextran than in the thick ACM, but this characteristic was reversed for the abluminal side. The porcine bladder ACM possesses directional porosity and acellularizing stretched urinary bladders may increase structural density and alter fluid and macromolecule porosity. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 970–974, 2003
Risks and responses among the urban poor in India
Authors: Kantor Paula , Nair Padmaja
Published: November 2003

This paper describes the events faced by urban poor households in Lucknow, India and household responses in the face of these events. Using household and individual data collected in 2002 from 12 slum settlements, the authors found that certain events, such as illness and social and religious spending, are more frequent than others and that some groups, characterized by gender of head of household, community and economic status, experience certain event types more than others. It also found that some less frequent events may be very burdensome due to their high severity. Responses to common event types exhibited a pattern. Households reduced consumption, used savings and took loans much more frequently than other options, across event types. Variations in responses were identified by event type and severity and economic status. The results illustrate the need for both protective and promotive interventions to improve livelihood security among the urban poor. Copyright © 2003 John Wiley & Sons, Ltd.
Aid and public sector borrowing in developing countries
Authors: Feeny Simon , McGillivray Mark
Published: November 2003

This paper analyses the relationship between public sector borrowing and foreign development aid. It is concerned specifically with the public sector borrowing requirement net of aid, questioning the assumption that aid and this type of borrowing are substitutes for one another. After looking at the public sector budget constraint and various conditions under which aid might lead to an increase in this borrowing, the paper surveys the empirical results of literature on aid and public sector fiscal behaviour. It finds that the results of a number of studies are consistent with aid leading to increases in this borrowing. Further investigation, in the form of econometric analysis of panel data, also points to this outcome. Copyright © 2003 John Wiley & Sons, Ltd.
International trade in ‘quality goods’: signalling problems for developing countries
Authors: Hudson John , Jones Philip
Published: November 2003

Consumers evaluate product quality with information signals such as brand name giving an advantage to established firms over other firms even when introducing a new product. Another signal is ‘country of origin’ and, as high‐income countries focus more heavily on higher quality goods, there is a tendency for consumers to associate quality with a country's income per capita. Thus new firms from developing countries face particular problems in export markets. International standardization offers a potential solution to their problem. However, analysis of the use of ISO 9000 suggests that it is difficult to eliminate the informational asymmetry. Copyright © 2003 John Wiley & Sons, Ltd.
From microcredit to microfinance: evolution of savings products by MFIs in Bangladesh
Authors: Dowla Asif , Alamgir Dewan
Published: November 2003

This paper chronicles how the microfinance industry in Bangladesh has evolved from its initial focus on credit, disbursing standardized loan products and collecting obligatory savings to the development of flexible savings products. We describe the process through which the industry gradually moved away from compulsory savings and introduce flexible savings. We provide detailed descriptions of various savings related products used by MFIs in Bangladesh. We point out the numerous problems that can arise when MFIs collects savings especially from non‐members without a proper legal framework. We conclude the paper by suggesting prudent regulation of MFIs to ensure the security of the meager savings of the poor. Copyright © 2003 John Wiley & Sons, Ltd.
Causes of inequalities in China, 1952 to 1999
Authors: Bhalla Ajit S. , Yao Shujie , Zhang Zongyi
Published: November 2003

This paper presents a comprehensive picture of inequality in China on the basis of provincial data. It decomposes overall inequalities into intra and inter components. Rural–urban inequality dominated overall inequality in the past and will continue to do so in the future. Meanwhile, in recent years inter‐regional inequality has grown rapidly and become an important component of inequality. We find that the pattern of inequality is quite different in the pre‐reform and reform periods. Our results show that overall inequality in China is large by international standards and that it has grown worse during the past half century. Copyright © 2003 John Wiley & Sons, Ltd.
Resource inflows and household composition: evidence from South African panel data
Authors: Maitra Pushkar , Ray Ranjan
Published: November 2003

Economic analysis of household behaviour, usually, assumes that household size and composition are fixed and exogenous. This study departs from this practice by analysing resource and household compositional variables, using an interdependent framework that treats them as jointly endogenous. The study is conducted using panel data set of Black households residing in Kwazulu Natal province in South Africa. The results provide evidence of fluidity of household structure, and point to new hypotheses on the effects of household resources on household composition. Copyright © 2003 John Wiley & Sons, Ltd.
Transnational corporations and the discourse of water privatization
Authors: Robbins Peter T.
Published: November 2003

Faced with a well‐documented fresh water crisis in many parts of the world, international institutions are advocating market‐based solutions involving the privatization and commodification of water. The definition of water as a commodity by multilateral organizations in the early 1990s allowed a handful of transnational corporations, supported by the World Bank and the IMF, to become centrally involved in management of public water services in poorer countries. The years 2000 to 2003 saw the retreat of TNC investment in water due to national economic crises, social protest, and the difficulties of extracting profit delivering water to indigent consumers. This article examines the shift in discursive strategy of development organizations, and the resulting rise and fall of TNC involvement in water and sanitation provision in the Third World. Copyright © 2003 John Wiley & Sons, Ltd.
Preparative isolation and characterization of zinc dialkyldithiophosphates from commercial antiwear additives
Authors: Carbognani Lante
Published: November 2003

An automated HPLC separation methodology was developed for the preparative separation of ZnDTP components from commercial lubricant antiwear additives. Using silica columns that can be reactivated by elution with appropriate solvents, gram quantities of additives can be isolated. The isolated materials are useful for carrying out further mechanistic and synthetic studies. Preliminary estimations suggest that separation repeatability and fraction recoveries have acceptable levels. Qualitative characterization of isolated ZnDTP mixtures was achieved by IR, TLC‐FID, and RP‐HPLC. IR is useful for assessing the nature of ZnDTP alcoholic moieties. TLC‐FID provides a check on the preparative HPLC separation efficiency. RP‐HPLC on octadecylsil‐silica columns provides fingerprints for isolated commercial ZnDTP active concentrates. Fingerprinting on small bore HPLC columns proved advantageous compared with conventional columns.
Enhancing the sensitivity of capillary electrophoresis using a microcolumn solid phase extraction setup
Authors: Zhang Pudun , Xu Guowang , Xiong Jianhui , Zheng Yufang , Shi Xianzhe , Yang Qing , Wei Fusheng
Published: November 2003

In this paper, a setup called micro‐column solid phase extraction (MicroSPE) was developed to enhance the sensitivity of capillary electrophoresis. The setup consists of a manual pump, several insulin syringes, and a Teflon extraction cartridge. The cartridge was made of 2–4 mm irregular C18 solid phase materials in a Teflon tube (375 μm ID) with glass fiber frits. Two pieces of capillary tubing were connected to both the ends of the cartridge. Using sulindac‐spiked urine as the test sample, the extraction and analytical conditions were investigated in detail. When 1 μL 70/30 methanol/water was applied as the elution solvent, satisfactory results could be obtained. The internal standard method was used to quantitatively determine the compound in urine. The detection limit for sulindac was 2.9 ng/mL and the enrichment factor reaches more than 260. The result illustrates that the MicroSPE setup has a significant concentrating effect and is suitable for preconcentrating and cleaning‐up samples with complex matrices.
Direct separation and quantitative determination of glimepiride isomers by high performance liquid chromatography
Authors: Song Yaru , Niu Liping , Wang Defa , Hu Yuping , Hou Dongyan
Published: November 2003

A simple and sensitive high‐performance liquid chromatographic procedure for the determination of the trans isomer of glimepiride is reported. Chromatography accomplished direct separation of the cis and trans isomers of glimepiride on a Dikmonsil C18 (250×4.6 mm, 5 μm) column with a mobile phase consisting of methanol‐acetonitrile‐NH4Ac buffer solution (1.5 mol L–1, pH = 4.5) (1.1 : 1.3 : 1.0, v/v) at a flow rate 0.5 mL min–1. The resolution (RS) was 1.73 with a retention time of 24.885 and 23.018 min for the cis and the trans isomer, respectively. A standard linear calibration curve was established for the trans isomer of glimepiride over the range of 4.95–198.00 μg mL–1 with a correlation coefficient of 0.99997. This method has been successfully used to analyze four different kinds of glimepiride product.
Capillary electrochromatography with bare silicas of different pore sizes as stationary phases
Authors: Steiner Frank , Lobert Thorsten
Published: November 2003

Bare silica can be used with reversed phase eluents for the chromatographic separation of basic analytes. It provides high surface charge density within a certain pH range, thus generating a high electroosmotic flow (EOF) when applied in electrochromatography. The influence of pore size on EOF velocity and mass transport is demonstrated. High EOF and fast mass transfer were encountered with 100 nm and 200 nm material and related to a pore perfusion mechanism. On a silica with 200 nm average pore size at pH 7, an EOF velocity of 2 mm/s was obtained at 600 V/cm. Silicas with pore diameters between 6 nm and 200 nm, corresponding to surface areas between 500 m/g and 10 m/g (data calculated from inverse size exclusion chromatography experiments), were used for CEC and HPLC separation of strongly basic solutes. On separation of tricyclic antidepressants by CEC, “normal” and “abnormal” efficiencies were achieved and were found to vary with the charge density within the separation column.
Determination of new pyridoquinoline derivatives and their quantification in urine by capillary liquid chromatography
Authors: Srbek Jan , Coufal Pavel , Tesařová Eva , Bosáková Zuzana , Suchánková Jana
Published: November 2003

Capillary liquid chromatography (CLC) in reversed separation mode was applied to the quantification and impurity profile determination of eight newly synthesized pyridoquinolines. The CLC separation system consisted of Nucleosil C18 stationary phase and methanol containing 1% (v/v) of triethylamine (TEA) as the mobile phase. The optimized separation system enabled the separation of impurities from the main component and their quantification in a reasonable analysis time. The presence of TEA in the mobile phase greatly improved the peak shape and decreased the analysis time of the studied derivatives on the C18 stationary phase. Calibration curves of pyridoquinolines were plotted in a concentration range from 1.0×10–6 to 1.0×10–3 mol/L at two parallel detector wavelengths of 254 and 265 nm and subsequently used for quantification of pyridoquinoline derivatives in human urine. No pretreatment of the real biological sample was needed. Detection and quantification limits were calculated for all the derivatives and the detection limits of most of the pyridoquinolines were found to lie in the μmol/L concentration range. The proposed CLC separation system has proved to be a suitable method for quantification of test derivatives in samples containing human urine matrix.