bluuebunny/crossref_metadata_2025_split huggingface dataset:
Endothelial cells on dacron vascular prostheses: Adherence, growth, and susceptibility to neutrophils
Authors: Tunstall Ann , Eberhart Robert C. , Prager Morton D. 
Published: May 2005

AbstractHuman umbilical vein endothelial cells (HUVEC) on knitted and woven Dacron prostheses were compared with HUVEC on smooth surfaces (tissue culture polystyrene, PET film, and Natrix) with regard to adherence, growth, and susceptibility to injury by neutrophils (PMN). These are properties of importance for successful seeding or coating of prostheses. For prosthetic material of given macroscopic dimensions, more endothelial cells (EC) adhered than to smooth surfaces. However, the prostheses had a greater effective surface area as determined by the number of EC at confluency. When this parameter was taken into account, fewer EC were found adherent to prosthetic material per unit effective surface area than for the smooth surface substrates. Growth on prostheses was clearly inferior to that on smooth surfaces, and EC on prostheses were more susceptible to attack by activated PMN than on smooth surfaces. These differences may reflect the topographic differences in cells attached to fibers where they assume more distorted shapes by stretching to span fibers. © 1995 John Wiley & Sons, Inc.
Attachment and growth of cultured fibroblast cells on silk protein matrices
Authors: Minoura Norihiko , Aiba Sei‐Ichi , Gotoh Yohko , Tsukada Masuhiro , Imai Yohji 
Published: May 2005

AbstractThe attachment and growth of L‐929 cells on films made of Bombyx mori silk proteins—fibroin and sericin and their mixtures—was studied by a cell culture method. Both cell attachment and growth were dependent on a minimum of around 90% sericin in the mixture. The results from electron micrography as well as from the DSC measurements supported the notion that the mixture of the two proteins fibroin and sericin has a phase‐separated structure in the solid state. The observed minimum of sericin in the cell attachment and growth is thought to be a result of this phase‐separated structure. Films of pure component proteins (i.e., 100% fibroin or sericin) exhibited as high a cell attachment and growth as collagen, a widely used mammalian cell culture substrate. However, a morphological study of the attached cells revealed that the cells attached to silk fibroin were extended and had a spindle shape, just like the cells attached to collagen, while the cells attached to the silk sericin had a different shape. It is concluded, therefore, that the attachment condition on silk fibroin is ideal for the viability, growth and function of the cells. © 1995 John Wiley & Sons, Inc.
Cytotoxicity testing of poly(anhydride‐co‐imides) for orthopedic applications
Authors: Attawia Mohamed A. , Uhrich Kathryn E. , Botchwey Edward , Fan Miranda , Langer Robert , Laurencin Cato T. 
Published: May 2005

AbstractThe cytotoxicity of a series of poly(anhydride‐co‐imides) with osteoblast‐like cells (MC3T3‐E1) was evaluated. The imide component of the copolymers was based on trimellitylimidoglycine (TMA‐gly), and the anhydride component was based on either sebacic acid (SA) or 1,6‐bis(carboxyphenoxy)hexane (CPH). Cell adhesion and proliferation on surfaces of the polymer discs were observed by environmental scanning electron microscopy (ESEM). During the first 24 h of attachment, cells showed normal morphology when cultured on the various copolymers of CPH. Concurrently, the effects of polymer breakdown products on osteoblast‐like cells were evaluated by studying their proliferation (cell numbers), viability (dye exclusion), and morphology (light microscopy). Cell cultures in the presence of these breakdown products resulted in normal morphologies and reached confluency after 7 days. This initial in vitro evaluation with osteoblast‐like cells suggests that the poly‐(anhydride‐co‐imides) may be viable carriers for osteoblasts. © 1995 John Wiley & Sons, Inc.
Prevention of bone loss by percutaneous estradiol implants in ovariectomized rats
Authors: Yamamura Keiko , Iwata Hisashi , Osada Takashi , Yano Kohji , Yotsuyanagi Toshihisa , Nabeshima Toshitaka 
Published: May 2005

AbstractThis study was conducted to investigate whether hydroxyapatite (HAP) is appropriate as a percutaneous drug carrier for estradiol (E2) for the suppression of bone loss. Ten‐week‐old female Sprague–Dawley rats were subjected either to bilateral ovariectomy (OVX) or to sham surgery (control). Ovariectomized rats were implanted percutaneously with E2‐HAP disks containing low, medium or high doses of estradiol (50, 250, or 500 μg E2/rat, respectively). Ovariectomized rats without implant and OVX rats implanted only with HAP served as additional controls. All rats were sacrificed 90 days after surgery. At the end of the experiment, bone mineral density of the lumbar spine was measured by dual energy X‐ray absorption, and serum E2 was assayed by radioimmunoassay. The bone mineral density of OVX and HAP‐treated OVX rats decreased by 18% compared to sham surgery rats, but decreased by only 13, 7, and 3% in rats treated with 50, 250, and 500 μg E2/rat, respectively. The in vitro release of E2 from E2‐HAP devices was determined by an HPLC method. Estradiol release from the HAP devices followed almost a zero‐order kinetics. Estradiol remained intact in E2‐HAP implants for up to six months when stored at 5, 25, and 40°C. This study indicates that E2‐HAP implants are effective in suppressing bone loss in the spine of OVX rats in a dose‐dependent manner. © 1995 John Wiley & Sons, Inc.
Antithrombin activity of surface‐bound heparin studied under flow conditions
Authors: Lindhout T. , Blezer R. , Schoen P. , Willems G. M. , Fouache B. , Verhoeven M. , Hendriks M. , Cahalan L. , Cahalan P. T. 
Published: May 2005

AbstractPolyacrylamide‐grafted polyetherurethane sheets were modified by end‐point and multipoint attachment of heparin. The surface‐bound heparin was firmly attached. No release of heparin activity could be detected when the surface was rinsed at a wall shear rate of 2000 s−1. Uptake of antithrombin and thrombin inactivation were investigated under well‐defined flow conditions by the use of a spinning device with an attached disk‐shaped heparinized surface. It is demonstrated that the rate of thrombin inactivation at the antithrombin‐heparin surface equals the maximal rate of transport of thrombin toward the surface when the surface coverage of antithrombin exceeds 10 pmol/cm2. This result indicates that a higher intrinsic catalytic efficiency of a surface does not necessarily result in a higher antithrombin activity. We varied the heparin content of the surfaces between 0 and 35 μg/cm2 by increasing the number of functional groups to which heparin could be covalently attached. The uptake of antithrombin increased with the heparin content of the surface, but the stoichiometry decreased from 2 to 0.5 pmol antithrombin/μg heparin. Apparently, antithrombin could not bind to heparins buried in the poly(acrylamide) layer. The rate of thrombin inactivation at surfaces with low heparin content (2 μg/cm2) fells below the transport limit of thrombin and became proportional with the heparin content of the surface. Although the contribution of surface‐bound heparin to the neutralization of fluidphase thrombin was found to be negligible compared with the effect of fluid‐phase antithrombin at physiologic relevant concentrations, these heparinized surfaces markedly delayed the onset of thrombin generation in platelet‐rich plasma. It is concluded that the inhibition of locally produced thrombin might contribute to the thromboresistance of the heparinized surface. © 1995 John Wiley & Sons, Inc.
Role for interleukin‐4 in foreign‐body giant cell formation on a poly(etherurethane urea) in vivo
Authors: Kao Weiyuan John , McNally Amy K. , Hiltner Anne , Anderson James M. 
Published: May 2005

AbstractInterleukin‐4 (IL‐4) was previously shown to induce extensive macrophage fusion to form foreign‐body giant cells (FBGCs) in vitro. In the present study, our goal was to extend these findings to an in vivo test environment on biomaterials. The subcutaneous cage‐implant system was modified for mice to elucidate IL‐4 participation in mediating FBGC formation in vivo. Exudate leukocyte concentrations from cages containing poly(etherurethane urea) (PEUU A′) and empty cage controls indicated a similar inflammatory response that turned toward resolution by 14 days postimplantation, thus confirming the applicability of the cage‐implant system in mice. FBGC kinetic analysis showed that the formation of mouse FBGCs occurs through the fusion of adherent macrophages at a constant rate up to 14 days of implantation. Purified goat anti‐mouse IL‐4 neutralizing antibody (IL4Ab) or normal goat nonspecific control IgG (gtIgG) at various concentrations, or recombinant murine IL‐4 (muIL4) was injected into the implanted cages containing PEUU A′ every 2 days for 7 days. The injection of IL4Ab significantly decreased the FBGC density on PEUU A′ cage‐implanted in mice, when compared with the nonspecific IgG or PBS injection controls. Conversely, the FBGC density was significantly increased by the injection of muIL4 when compared with nonspecific IgG and PBS injection controls. Adherent macrophage density, FBGC morphology, FBGC average size, and size distribution were not significantly different among IL4Ab, nonspecific control gtIgG, muIL4, and PBS control groups. Our data suggest that IL‐4 participates in FBGC formation on biomaterials in vivo. © 1995 John Wiley & Sons, Inc.
Surface‐modified poly(methyl methacrylate) enhances adsorption and retains anticandidal activities of salivary histatin 5
Authors: Edgerton M. , Raj P. A. , Levine M. J. 
Published: May 2005

AbstractDenture‐induced stomatitis is a common intraoral disease which is associated with high levels of Candida albicans adhesion to a denture surface. The aim of this study was to produce a surface‐modified denture resin, which is usually manufactured from poly(methyl methacrylate) (PMMA), carrying an immobilized anticandidal protein. PMMA was modified by surface polymerization of methyl methacrylic acid to enhance adsorption of a potent candidacidal salivary protein, histatin 5. The modified PMMA showed higher surface adsorption and desorption of histatin 5 than the unmodified material. Because histatin 5 destabilizes C. albicans cell membranes and allows efflux of intracellular molecules, candidacidal activity was monitored by dye release from fungal cells. Adsorbed histatin 5 did not release dye from the yeast cells; however, dye was detected as histatin was desorbed from the surface. In an adhesion assay, modified PMMA decreased human submandibular–sublingual saliva (HSMSL) mediated adherence of yeast cells to the polymer. Precoating histatin 5 onto unmodified PMMA also abolished HSMSL‐mediated adhesion. These experiments show that dental acrylic may be surface modified and loaded with histatin 5 as a means of controlled release of histatin 5 to an affected area. This surface modification may additionally reduce adhesion of C. albicans cells to the saliva‐coated material. © 1995 John Wiley & Sons, Inc.
Structural evaluation of human and sheep bone and comparison with synthetic hydroxyapatite by FT‐Raman spectroscopy
Authors: Rehman I. , Smith R. , Hench L. L. , Bonfield W. 
Published: May 2005

AbstractThe composition of whole human and sheep cortical bone tissue, and of a synthetic hydroxyapatite (P120), were compared using Fourier transform Raman (FT‐Raman) spectroscopy. Deproteination procedures to remove the bulk of the collagen present in bone tissue allowed isolation of the mineral phase. A comparison of the spectra obtained from both whole and deproteinated bone with those of synthetic hydroxyapatite showed direct correlation only in the region of 952 cm−1 (symmetric PO mode). In contrast, human and sheep bone were very closely matched in both, the organic and inorganic structures. The results demonstrate that deproteination of bone is not a necessary precursor to obtain spectral information. © 1995 John Wiley & Sons, Inc.
A study of reversibly inactivated lipases for use in a morphine‐triggered naltrexone delivery system
Authors: Nakayama G. R. , Roskos K. V. , Fritzinger B. K. , Heller J. 
Published: May 2005

AbstractA key component of an implant that can be triggered by external morphine to release naltrexone is an inactivated enzyme that can be activated by morphine and which can then rapidly remove a protective coating surrounding a bioerodible polymer containing dispersed naltrexone. In this article we describe a lipase that has been conjugated with O3‐carboxymethylmorphine, morphine‐β‐3‐glucuronide and O3‐carboxypropylmorphine. The enzyme conjugate was then inactivated by complexation with affinity‐purified goat polyclonal antimorphine antibodies. Antibody lipase interactions were measured by pH Stat and ELISA techniques. Affinity constants of the antibodies determined by radioimmunoassay using tritium‐labeled morphine were 4.10 × 106, 3.18 × 106 and 3.38 × 107, respectively. While a concentration of 10−5 M morphine was required to restore lipase activity, it is likely that a combination of correct morphine tether and correct affinity‐purified antibody can increase sensitivity to the desired 10−8−10−9 M morphine level. Thus, a functioning device can almost certainly be constructed. However, it is unlikely that reactivation times of 1–2 h necessary for clinical usefulness in treatment of narcotic addiction can be achieved. © 1995 John Wiley & Sons, Inc.
X‐ray powder diffraction patterns of calcium phosphates analyzed by the Rietveld method
Authors: Keller Ludwig 
Published: May 2005

AbstractLeast‐square refinement of x‐ray powder diffraction patterns analyzed by the Rietveld method can yield structural information which had been unattainable or at least elaborate to obtain by conventional pattern analysis. The Rietveld method calculates a powder pattern on the basis of a structural model as well as the characteristics of the instrument used, and minimizes the differences between the intensities observed and the intensities calculated. The method is applied on patterns produced powders or polycrystalline solids on conventional powder diffractometers. For materials containing more than one crystalline phase with known structures such as hydroxyapatite (HA) and whitlockite (β‐TCP), pattern analysis yields phase quantification without internal or external standards. Refinement of the lattice parametersa0andc0determines the degree of dehydroxylation in plasma‐sprayed HA coatings. The presence of amorphous Ca phosphates in HA coatings is detected by background modeling. The calculation of entire powder patterns allows discrimination of small concentrations of poorly crystallized Ca phosphate phases against the background, and prevents gross aberrations in estimating secondary phases. Even defect structures such as an OH‐deficient HA lattice can be detected through slight differences in diffracted intensity by which the pattern calculated deviates from the pattern observed. © 1995 John Wiley & Sons, Inc.
Adhesion and spreading of human skin fibroblasts on physicochemically characterized gradient surfaces
Authors: Ruardy T. G. , Schakenraad J. M. , van der Mei H. C. , Busscher H. J. 
Published: May 2005

AbstractIn this study, adhesion and spreading of human skin fibroblasts on gradient surfaces of dichlorodimethylsilane (DDS) coupled to glass was investigated. Gradient surfaces were prepared by the diffusion technique and characterized by the Wilhelmy plate technique for their wettability and by scanning x‐ray photoelectron spectroscopy for their chemical surface composition. A linear relation between the gradient length, based on advancing water contact angles, and the square root of the diffusion time of DDS was observed. XPS analysis and the cellular experiments were carried out on gradient surfaces prepared using diffusion time of 3 h. A continuously varying chemical composition over the length of the gradient surfaces observed with the Si/O elemental surface concentration ratio being highest on the hydrophobic end of the gradient surfaces. In the presence of serum proteins, human skin fibroblasts seeded on these gradient surfaces showed a preferential adhesion onto the steepest part of the gradient, probably due to an optimal local wettability and/or local chemistry. Furthermore, it was shown that the spread area of human fibroblasts increased over the length of the gradient surface when going from the hydrophobic to the hydrophilic end. Summarizing, this study shows that the use of gradient surfaces to study cellular responses to materials surface properties, like wettability, yields more‐convincing conclusions than the use of a variety of materials with different wettabilities due to the control of the specific surface chemistry of gradient surfaces. © 1995 John Wiley & Sons, Inc.
Noncontact microstrain measurements in orthodontic wires
Authors: Kirkpatrick Sean J. , Duncan Donald D. 
Published: May 2005

AbstractA technique is presented that allows for highly sensitive and highly accurate measurements of microstrain in biomaterials. It is particularly useful for measuring strains in materials where the use of conventional extensometers or strain gauges is impracticable, such as in reinforcement fibers and orthodontic wires and in hostile environments. The technique is based on the well known technique of observing translating laser speckle with a linear‐array charge‐coupled device (CCD) camera. However, it employs a relatively new data processing algorithm involving a twodimensional frequency transform of the data. Advantages of the technique include: insensitivity to slow surface microstructure changes, insensitivity to zero‐mean noise processes, compact design, modest resolution requirements, and the fact that it is truly noncontact. Strain rate measurements were made on an 0.028‐gauge round stainless steel orthodontic wire as an example of this technique. The Young's modulus of the wire based on the speckle technique was 2.04 × 1011 Nm−2, which is very close to the textbook value. © 1995 John Wiley & Sons, Inc.
Mechanical and histological investigation of hydrothermally treated and untreated anodic titanium oxide films containing Ca and P
Authors: Ishizawa H. , Fujino M. , Ogino M. 
Published: May 2005

AbstractIn a previous study a new method for forming thin hydroxyapatite (HA) layers on titanium was described. Titanium was anodized at 350 V in an electrolytic solution containing sodium β‐glycerophosphate and calcium acetate, and an anodic titanium oxide film containing Ca and P (AOFCP) was formed on the surface. Then numerous HA crystals were precipitated on the AOFCP during hydrothermal treatment in high‐pressure steam at 300°C. In this study three types of hydrothermally treated films differing in amounts of precipitated HA crystals and tensile adhesive strength, and untreated films were histologically and mechanically investigated in a transcortical rabbit femoral model for 8 weeks of implantation using light microscopy, scanning electron microscopy (SEM), and push‐out tests. Machined titanium and HA ceramics served as control materials. The push‐out shear strength and bone apposition of the AOFCP significantly increased after hydrothermal treatment, and were equivalent to those of HA ceramics, although the HA layer on the AOFCP was thin at 1–2 μm. From SEM observation of the pushed‐out specimen, it was found that the thin HA layer had directly bonded to bone but the AOFCP had not. The push‐out strength of the hydrothermally treated film resulted from the chemical bonding of the bone–HA layer interface, while that of the untreated film resulted from mechanical interlocking force between bone and the microprojections. There was a small difference in bone apposition but no significant difference in push‐out strength with the amount of precipitated HA crystals on the treated films. Among the treated films, the film formed at the lowest electrolyte concentration showed the lowest bone apposition because of incomplete covering by the HA crystals, and showed the highest stability against mechanical failure because the adhesive strength was very high at about 38 MPa. Also, the hydrothermally untreated anodic oxide films, whose surfaces were rough as a result of the large microprojections, showed much higher push‐out strength and bone apposition than titanium. The good hard‐tissue compatibility may be attributed to the surface roughness and the possible inhibition of titanium ion release from the specimen. © 1995 John Wiley & Sons, Inc.
Changes in phases and crystallinity of plasma‐sprayed hydroxyapatite coatings under heat treatment: A quantitative study
Authors: Wang B. C. , Chang E. , Lee T. M. , Yang C. Y. 
Published: May 2005

AbstractWith three kinds of plasma‐sprayed hydroxyapatite coatings (HACs) prepared, the objectives of this study were (1) to establish the calibration methods for quantitatively measuring the concentration of impurity phases and the degree of crystallinity of the HACs, and (2) to explore the effects of postheat treatments at various temperatures in vacuo on the changes of phases and crystallinity of the HACs. By the internal standard method used, the concentrations of impurity phases, such as α‐TCP, β‐TCP, and TP, of the assprayed HACs were significantly higher than those measured by the direct intensity‐ratio method, and the CaO phase was lower than the direct intensity‐ratio method. When the HACs were heat treated in the temperature interval 630–850°C, the concentrations of impurity phases obviously decreased, and the coating crystallinity apparently increased. After annealing at 850°C, an HAC consisting of at least 95% crystallinity with few impurity phases was obtained. As the annealing temperatures in the interval 850–1000°C were applied, however, the HA phase seriously decomposed, resulting in the appearance of a large number (higher than 20 wt%) of impurity phases in the HACs. This work suggests that the optimum heat treatment conditions in vacuo for maximizing crystallinity and minimizing impurity phases of the HACs do not occur at the same temperature. © 1995 John Wiley & Sons, Inc.
Neovascularization of synthetic membranes directed by membrane microarchitecture
Authors: Brauker James H. , Carr‐Brendel Victoria E. , Martinson Laura A. , Crudele Joanne , Johnston William D. , Johnson Robert C. 
Published: May 2005

AbstractTransplantation of tissues enclosed within a membrane device designed to protect the cells from immune rejection (immunoisolation) provides an opportunity to treat a variety of disease conditions. Successful implementation of immunoisolation has been hampered by the foreign‐body reaction to biomaterials. We screened a variety of commercially available membranes for foreign‐body reactions following implantation under the skin of rats. Histologic analysis revealed that neovascularization at the membrane–tissue interface occurred in several membranes that had pore sizes large enough to allow complete penetration by host cells (0.8‐8‐μm pore size). When the vascularization of the membrane–tissue interface of 5‐μm‐pore‐size polytetrafluoroethylene (PTFE) membranes was compared to 0.02‐μm‐pore‐size PTFE membranes, it was found that the larger pore membranes had 80–100‐fold more vascular structures. The increased vascularization was observed even though the larger pore membrane was laminated to a smaller pore inner membrane to prevent cell entry into the prototype immunoisolation device. This significantly higher level of vascularization was maintained for 1 year in the subcutaneous site in rats. © 1995 John Wiley & Sons, Inc.