bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation of poly(glycolic acid) bonded fiber structures for cell attachment and transplantation
Authors: Mikos Antonios G. , Bao Yuan , Cima Linda G. , Ingber Donald E. , Vacanti Joseph P. , Langer Robert 
Published: May 2005

AbstractA novel method was developed to prepare threedimensional structures with desired shapes used as templates for cell transplantation. The produced biomaterials are highly porous with large surface/volume and provide the necessary space for attachment and proliferation of the transplanted cells. The processing technique calls for the formation of a composite material with nonbonded fibers embedded in a matrix followed by thermal treatment and the selective dissolution of the matrix. To evaluate the technique, poly(glycolic acid) (PGA) fiber meshes were bonded using poly(L‐lactic acid) (PLLA) as a matrix. The bonded structures were highly porous with values of porosity up to 0.81 and area/volume ratios as high as 0.05 μm−1. © 1993 John Wiley & Sons, Inc.
Determination of the role of cuticular carbohydrates in the hemocompatibility of Dirofilaria immitis (Nematoda)
Authors: Kadipasaoglu Kamuran A. , Bilge Fertac H. , Baier Robert E. 
Published: May 2005

AbstractWe have partially characterized surface glycoproteins of the canine heartworm, Dirofilaria immitis. Histochemical studies indicated the presence of neutral and acidic mucopolysaccharides at the blood–cuticle interface. Fluorescein isothiocyanate‐conjugated lectin binding patterns suggested the presence of α‐D‐glucosyl and/ or α‐D‐mannosyl, β‐galactosyl, N‐acetylneuraminyl and N‐acetylated‐D‐hexosaminyl (sialic and glucuronic acids, respectively) terminal residues among the constituent sugars of the glycocalyx. An additional goal of this study was to assess the significance of each carbohydrate in parasite hemocompatibility by using scanning electron microscopy, internal reflection infrared spectroscopy, and comprehensive contact angle measurements. Each carbohydrate identified in the glycocalyx was selectively cleaved with the appropriate exoglycosidase. Heartworms bearing native and enzyme‐altered surfaces were exposed to platelet‐rich canine plasma. Activation and aggregation of platelets were significantly increased on enzyme‐treated surfaces as compared with native surfaces. Enzyme‐induced cleavage of carbohydrate residues was associated with an increase in critical surface tension or a loss in cuticular structural integrity or both. Hemocompatibility of the heartworm cuticle depends on the retention of a stable saccharide‐rich layer that minimizes interaction with plasma proteins and platelets; thus, carbohydrate residues on the glycocalyx may contribute to parasite hemocompatibility. The presence of similar low‐critical‐surface‐tension coatings with high mechanical integrity may impart thromboresistance to other polyphenolic or chitinous substances. © 1993 John Wiley & Sons, Inc.
Uptake of metal cations by fibroblasts in vitro
Authors: Wataha J. C. , Hanks C. T. , Craig R. G. 
Published: May 2005

AbstractAtomic absorption spectroscopy was used to assess uptake of Ag+1, Au+4, Cd+2, Cu+2, In+3, Ni+2, Pd+2, and Zn+2 by in vitro cultures of Balb/c 3T3 fibroblasts as a function of concentration of the cations in cell‐culture medium. Reversibility of this uptake was also measured. Metal cations exhibited a 400‐fold difference in their tendency to accumulate in the cells; In+3 tended to accumulate the most, whereas Pd+2 accumulated the least. Uptake of the cations in the cells increased linearly with the concentration of the cation in the medium for all cations up to their 50% toxicity concentrations. Reversal of this uptake was slower than that of the initial uptake for three cations studied in more detail (Cd+2, In+3, and Ni+2). The duration of the initial exposure affected the proportion of the metal cations that were retained by the cells 5 h after the cations were removed from the medium. The proportion of retained Cd+2 did not change when the initial exposure was increased from 2 h to 6 h, whereas the proportion of retained In+3 decreased and Ni+2 increased over the same period. The tendency of the cells to accumulate these cations correlated with their cytotoxic potency (measured previously). © 1993 John Wiley & Sons, Inc.
Tissue reaction to alumina implants inserted into the tibiae of rats
Authors: Takeshita Fumitaka , Morimoto Keizo , Suetsugu Tsuneo 
Published: May 2005

AbstractWe examined the tissue reaction to three alumina implants—single‐crystal alumina (SA), dense polycrystal alumina (DPA), and porous polycrystal alumina (PPA)—inserted transcortically, extending into the medullary canal of rat tibiae, and assessed the quantitative differences in bone reaction using an image processing system. There was no difference in the degree of maturation of newly formed bone around the three kinds of alumina. SA and DPA were encapsulated with a continuous bone layer, but some bone tissue was attached focally around PPA. Bone trabeculae in the control site diminished in size and number chronologically. Multinucleated giant cells were observed on the surface of DPA and PPA, but not on SA. Tabulation of the quantitative evaluation indicated that SA showed the highest, DPA a lower, and PPA the lowest in bone contact rate, bone contact thickness, and bone contact area. These data suggest that SA is superior to the other two as an implant material. © 1993 John Wiley & Sons, Inc.
Solution effects on the surface reactions of a bioactive glass
Authors: Filgueiras M. Regina , La Torre Guy , Hench Larry L. 
Published: May 2005

AbstractThe in vitro surface reactions of a 45S5 bioactive glass in three simulated body fluids (SBF) are analyzed using Fourier transform infrared (FTIR) spectroscopy. Five reaction stages are observed. Calcium and phosphate ions in SBF accelerate to a small extent the repolymerization of silica (Stage 3) and formation of an amorphous calcium‐phosphate (a‐CP) layer (Stage 4) on the glass surface. The a‐CaP layer is crystallized to form hydroxycarbonate apatite (HCAp) (Stage 5) more rapidly in the Ca‐and P‐containing SBF solutions (in 90 min rather than 120 min). However, Mg ions in SBF slow down formation of the a‐CaP layer and greatly retard crystallization of HCAp on the glass surface. © 1993 John Wiley & Sons, Inc.
Analysis of apatite deposits on substrates
Authors: Dasarathy Harini , Riley Clyde , Coble H. Dwain 
Published: May 2005

AbstractCalcium phosphate coatings, important for medical implant applications can occur in several different phases. Because of differences in properties of these phases it is imperative to be able to identify their presence in a substrate's coating. In this study we characterized hydroxy apatite (HA) surfaces applied by four different coating procedures. Included were plasma sprayed, sputtered, a composite, and a composite overlayed with plasma sprayed. It was found that a combination of reflectance infrared and Raman spectroscopy could be utilized to make an in situ characterization of the calcium phosphate phases. It was shown that plasma sprayed and sputtered coatings of HA lost OH and thus decreased in crystallinity, while composite coatings remained unchanged from the original HA powder. © 1993 John Wiley & Sons, Inc.
Effect of interfacial variables on metal‐porcelain bonding
Authors: Wagner Warren C. , Asgar Kamal , Bigelow W. C. , Flinn Richard A. 
Published: May 2005

AbstractWhile ceramic‐to‐metal bonding has been used in many applications, the actual chemical and physical factors leading to optimum bond strength are not well understood. In this work, several variables affecting the bonding between dental porelain and a palladium alloy (85% Pd, 10% Cu, and 5% Ga) were investigated: (1) precoating the metal by sputtering various oxides before porcelaining; (2) preoxidation of the metal base before porcelaining; (3) porcelaining under reducing atmosphere; and (4) surface roughening at controlled levels before porcelaining.Using a modification of the push doughnut shear bond strength test to measure bond strength the following results were obtained. (1) Compared with standard “control” samples, the aluminum oxide precoated precoated specimens showed a bond strength improvement of 46%, while the copper, manganese, and tin oxide precoatings exhibited smaller effects. (2) Preoxidation of the metal base led to pronounced bond strengthening (152%) by surface roughening as well as oxide formation. (3) Porcelaining under a reducing atmosphere severely reduced bond strength (88% lower than the controls) indicating the role of oxidation during the standard firing cycle. (4) Mechanical roughening of the surface by controlled amounts gave pronounced improvements with greater notch depth. Coarse roughening produced the highest bond strength improvements (486%). © 1993 John Wiley & Sons, Inc.
Evaluation of a relationship between polymer bulk hydroxyl and surface oxygen content and in vitro serum–material interaction
Authors: Sawada Koji , Shimoyama Takashi , Malchesky Paul S. , Goldcamp James B. , Omokawa Susumu 
Published: May 2005

AbstractTo evaluate serum‐material interaction for six types of minimodule and to assess the relationship between the interaction and chemical composition, notably bulk polymer hydroxyl (OH) percent of polymer, or surface oxygen (SO) percent, polymeric membranes with varying OH and SO percents were evaluated with normal human serum. The membrane materials (OH percent and SO percent) evaluated included polypropylene (PP; 0% and 1.9%), polyvinyl alcohol (PVA; 23.7% and 27.3%), ethylene vinyl alcohol (EVAL 4A and D; 30.4% and 25.3%), Cuprophan (CP; 31.5% and 37.4%), and Hemophan (HP; 30.9% and 23.6%), respectively. Data from serum perfusions expressed as percent changes to sham perfusion showed that solute percent decreases were less than 10% in all materials except PVA (10–22%). PVA and CP had higher C3a, C4a, and C5a, and C3a concentration increases, and had larger suppressive effects for all three mitogen‐induced mononuclear cell transformation functions (MNCTF) and concanavalin A‐induced MNCTF, respectively. PVA had higher SO percent than CP having lower or comparable bulk OH percent to EVAL or HP. The results obtained in the serum material interaction studies related more with the SO percent of the polymer rather than bulk OH percent. The differences for C4a and PHA‐induced MNCTF observed between the two EVAL membranes may be associated with significantly different pore size and therefore different surface structural properties. These results suggest that surface chemical (SO percent on the materials) and structural property analyses are important factors in biocompatibility parameter studies. © 1993 John Wiley & Sons, Inc.
Improved cortical histology after cementation with a new MMA‐DMA‐IBMA bone cement: An animal study
Authors: Nimb Lars , Stärup Jens , Jensen Jørgen Steen 
Published: May 2005

AbstractThe histological response of bone to inert bone wax, conventional polymethylmethacrylate (PMMA), and a new formulation of bone cement, methylmethacrylate/n‐decylmethacrylate/isobornylmethacrylate (MMA/DMA/IBMA) was investigated in canine tibial diaphysis. The new formulation of cement is characterized by a reduced exothermic temperature at curing and reduced leakage of chemicals to the adjacent bone. In comparison with bone wax, the MMA/DMA/IBMA bone cement did not differ significantly with respect to periosteal apposition and bone remodeling, although a tendency to inhibit the biological response was encountered. The MMA/DMA/IBMA was clearly superior to PMMA bone cement in respect to both bone necrosis and repair, as well as bone remodeling. © 1993 John Wiley & Sons, Inc.
Comparison of bone ingrowth into cobalt chrome sphere and titanium fiber mesh porous coated cementless canine acetabular components
Authors: Jasty Murali , Bragdon Charles R. , Haire Teresa , Mulroy Richard D. , Harris William H. 
Published: May 2005

AbstractBone ingrowth into uncemented hemispherical canine acetabular components porous‐coated with cobalt chrome spheres was compared to those porous‐coated with titanium fiber mesh. While good bone ingrowth was noted in both types of porous coatings at 6 weeks after surgery with no difference in the histologic quality of the ingrown bone, quantitation of bone ingrowth showed that significantly more bone grew into titanium fiber mesh porous‐coated components. The mean amount of bone ingrowth measured 10.5% of the area of the porous coating with fiber mesh coatings and only 5.5% of the area of the porous coating with spherical coatings (significant difference at P < .0005). The mean area density of the ingrown bone inside the pores measured 21.5% of the pore area with fiber mesh coatings, also significantly greater than 13.4% of the pore area with sphere coatings (P < .025). The ingrown bone penetrated a mean 66% of the depth of the porous layer with fiber mesh coatings compared to 32% of the depth of the porous layer with spherical coating (significant difference at P < .0005). The mean extent of the periphery of the porous layer with bone ingrowth was 88% for the mesh coatings and 55% for the spherical coatings (also a significant difference at P < .01). © 1993 John Wiley & Sons, Inc.
Osseous implant for studies of biomaterials using an in vivo electrochemical transducer
Authors: Casey Fox W. , Miller Michael A. 
Published: May 2005

AbstractThe in vitro and in vivo electrochemical behavior of commercially pure titanium (cp Ti) was characterized using a specialized osseous implant in conjunction with electrochemical impedance spectroscopy (EIS) measurement techniques. Studies performed in vitro were used to verify the operation of the transducer and develop methods of deconvoluting EIS data. This method was subsequently used to describe an electrochemical equivalent circuit model of the surface oxide and electrical doublelayer capacitance of cp Ti in the endogenous electrolyte found in the medullary compartment of a baboon tibia. Kinetic profiles of the double‐layer capacitance and the polarization resistance were constructed from multiple in vitro and in vivo EIS measurements performed over 60 min at 0 V (reference Ag/AgCI) conditioning potential. The profiles demonstrated that the growth of surface oxides was biphasic, with rapid decrease in the doublelayer capacitance occurring within 20 min and reaching steady‐state conditions at approximately 40 min. These data suggested that a passive, stable biofilm formed on the cp Ti surface in vivo and in vitro. © 1993 John Wiley & Sons, Inc.
Osteogenesis at the dental implant interface: High‐voltage electron microscopic and conventional transmission electron microscopic observations
Authors: Steflik D. E. , Sisk A. L. , Parr G. R. , Gardner L. K. , Hanes P. J. , Lake F. T. , Berkery D. J. , Brewer P. 
Published: May 2005

AbstractThe osteogenesis of mandibular bone to endosteal dental implants was examined using an in vivo dog model. One half of the implants examined were unloaded implants, with the remaining one half prosthodontically loaded for 6 months. Undecalcified mandibular implant samples were examined with both high‐voltage electron microscopy (HVEM) stereology and routine transmission electron microscopy. The osseous interface to integrated implants was shown to vary in its morphology. Mineralized bone was observed directly apposing the implant, often separated from the implant by an electron‐dense deposit of approximately 50 nm. Within this densely mineralized matrix, osteocytes were routinely observed. Adjacent areas were shown to contain slightly wider zones of either a less dense mineralized matrix or, alternatively, unmineralized tissue. Other zones consisted of wider unmineralized matrices containing collagen fibers and osteoblasts. These latter zones were consistent with the appearance of an appositional type of bone growth. Because bone is a dynamic, actively remodeling tissue, a varied morphology of the support tissues to dental implant is not unexpected. Areas of mature bone interfacing with successfully integrated implants were demonstrated, as well as areas adjacent to the mature bone that were undergoing remodeling or mineralization. This study has also shown that HVEM stereology is a valuable research tool to investigate the oral tissue interface with dental implants. © 1993 John Wiley & Sons, Inc.
Biocompatibility testing of restorative materials influencing dentin and pulp
Authors: Dejou J. , Remusat M. , Franquin J. C. 
Published: May 2005

AbstractA comparative study was carried out using 27 healthy human bicuspids that had been extracted for orthodontic reasons from adolescents 11–14 years old. A microphotometrical analysis of buccal and lingual odontoblast layer thickness was performed using the SAMBA 2000 system and the results were submitted to statistical comparison. The buccal odontoblast layer (BOL) was found to be thicker than the lingual odontoblast layer (LOL). These results were independent of age, sex, and tooth position in the dental arch. Moreover, a strong relationship existed between the layer thicknesses as linear function on a logarithmic scale. Standards for the evaluation of pulp–dentin biocompatibility are based essentially upon qualitative or semiquantitative histological criteria. A method of quantitative evaluation based upon microphotometrical measurements of the thickness of the buccal odontoblast layer, considered variable, and the lingual odontoblast layer, considered stable, was applied to coronal filling materials that had previously been tested by a classic method. Seventy bicuspids extracted from adolescents 11–14 years of age whose class‐V cavities had been filled in situ with one of four restorative materials, and whose residual dentin thickness was less than 750 μm, were divided into two groups: an intermediate‐term group (A) and a long‐term group (B); both groups were subdivided into four experimental series as a function of test materials. A microphotometrical analysis was carried out using an automatic scanning system (SAMBA 2000) for the quantification of buccal and lingual odontoblast layer thicknesses. The results confirmed that due to the stability of the LOL thickness it may legitimately be used as reference in the study of the analogous BOL thickness. The BOL variations seemed proportional to the biocompatibility of the material tested. The quantitative results obtained should provide an accurate comparison of the materials at a given period of observation and substantiate a follow‐up study of the evolution of biocompatibility. © 1993 John Wiley & Sons, Inc.
Polystyrene chemistry affects vitronectin activity: An explanation for cell attachment to tissue culture polystyrene but not to unmodified polystyrene
Authors: Steele John G. , Dalton B. Ann , Johnson Graham , Underwood P. Anne 
Published: May 2005

AbstractTissue culture polystyrene (TCPS) supports good attachment of adherent cells whereas unmodified polystyrene (PS) does not, but the mechanism of this difference is not well characterized. We have compared TCPS and PS for the amounts of vitronectin (Vn) and fibronectin (Fn) which adsorb from the fetal bovine serum (FBS) component of the culture medium. The significance of the amounts of Vn and Fn which adsorbed onto TCPS and PS was determined by reference to the concentration dependence of the cell attachment activity of Vn and Fn when adsorbed onto TCPS and PS, assayed using human vein endothelial cells and BHK‐21 fibroblasts. The amount of Vn which adsorbed onto TCPS from medium containing 3–30% (v/v) FBS was supraoptimal for the attachment of endothelial cells and fibroblasts. On PS, the amount of Vn which adsorbed from this medium was less than for TCPS and was suboptimal for cell attachment. Higher levels of Fn adsorbed onto TCPS than to PS, but even the amounts of Fn which adsorbed onto TCPS were suboptimal for cell attachment. We propose that the principal mechanistic difference between TCPS and PS for the initial attachment and spreading of cells is that more Vn adsorbs onto TCPS from the serum component of the culture medium. © 1993 John Wiley & Sons, Inc.
Neocartilage after artificial cartilage repair in the rabbit: Histology and proteoglycan fragments in joint fluid
Authors: Messner Karola , Lohmander L. Stefan , Gillquist Jan 
Published: May 2005

AbstractRepair of full‐thickness cartilage defects of the rabbit medial femoral condyle with artificial plugs and periosteal grafts was followed for 1 year. The morphological characteristics of the neocartilage after repair and the concentration of proteoglycan fragments in the joint fluid (CPFF) were evaluated. The CPFF showed only a weak correlation to the histological score of the neocartilage. Normal cartilage and subchondral bone did not develop with any of the repair alternatives. With a Dacron plug, neocartilage formation appeared earlier than with natural repair and was better than with periosteal grafting. Increased CPFFs were found in all specimens with repair at 3 months, probably reflecting the remaining effect of surgery. At 6 months, the CPFFs were again similar to those at the 3‐month evaluation. This was paralleled by a degeneration of the neocartilage. We conclude that Dacron plugs could serve as a scaffold for neocartilage formation. The CPFF reflected surgical trauma and late degeneration of neocartilage but did not indicate minor differences in quality between cartilage repair techniques, probably because of the limited size of the grafted defect. © 1993 John Wiley & Sons, Inc.
Kinetics of cell proliferation as a function of vascular graft material
Authors: Greisler Howard P. , Petsikas Dimitri , Lam Tina M. , Patel Narendra , Ellinger Joan , Cabusao Emma , Tattersall Charles W. , Kim Dae Un 
Published: May 2005

AbstractBioresorbable vascular grafts constructed for polyglactin 910 (PG910) and polydioxanone (PDS) and nonresorbable Dacron were interposed into the infrarenal abdominal aortas of New Zealand White rabbits. The prosthesis/tissue complexes were harvested after 2, 3, 4, 12, and 52 weeks. Seventeen, 9, and 1 h prior to sacrifice, animals received tritiated thymidine (0.5 mCi/kg/dose). All specimens were studied grossly and by light and transmission electron microscopy. Mitotic indices (MI's) were determined by autoradiography for inner capsule myofibroblasts at the proximal, mid, and distal segments of each prosthesis. There were no aortic‐related deaths. All grafts were patent with no aneurysmal dilatiation. At 4 weeks, PG910 resorption was evidenced by macrophage phagocytosis, less so in PDS while Dacron remained intact. At 12 weeks, the PG910 was completely resorbed while PDS resorption continued. The latter was completely resorbed by 52 weeks. There was no significant difference in MI's between proximal, mid, and distal regions for each graft type. The mitotic index paralleled the rate of prosthetic resorption in both PG910 and PDS groups, as high as 28.34 ± 23.21 in the former 3 weeks after implantation and significantly higher at 4 weeks (7.58 ± 2.02 and 7.50 ± 2.66, respectively) than at 52 weeks (0.72 ± 0.98 and 1.00 ± 0.22, respectively) in both groups. The mitotic index in the Dacron group never surpassed 1.22 ± 0.90.We conclude that higher levels of early cell proliferation in bioresorbable grafts closely parallel the kinetics of prosthetic resorption. © 1993 John Wiley & Sons, Inc.