bluuebunny/crossref_metadata_2025_split huggingface dataset:
Duplex stainless steels for osteosynthesis devices
Authors: Cigada A. , Rondelli G. , Vicentini B. , Giacomazzi M. , Roos A. 
Published: December 2004

AbstractThe austenitic stainless steels used today for the manufacture of osteosynthesis devices are sensitive to crvice corrosion. In this study the corrosion properties of some duplex stainless steels were evaluated and compared to traditional austenitic stainless steels. According to our results the following ranking was established: 23Cr4Ni < AISI 316L < ASTM F138 < 22Cr5Ni3Mo < 27Cr31Ni3.5Mo < 25Cr7Ni4MoN. In particular the results showed that the high‐performance 25Cr7Ni4MoN duplex stainless steel, with high molybdenum and nitrogen contents, can be considered not susceptible to crevice corrosion in the human body. The duplex stainless steels have also better mechanical properties at the same degree of cold working compared with austenitic stainless steels. Hence the 25Cr7Ni4MoN duplex stainless steel can be considered a convenient substitute of ASTM F138 for orthopedic and osteosynthesis devices.
Enhanced adherence of human adult endothelial cells to plasma discharge modified polyethylene terephthalate
Authors: Pratt Kerri J. , Williams Stuart K. , Jarrell Bruce E. 
Published: December 2004

AbstractHuman adult aortic endothelial cell attachment to polyethyleneterephthalate (PET as mylar film) was examined in vitro. PET was examined in both the unmodified form (PET −) and in a modified form (PET +) that had undergone plasma discharge surface modification (PDSM). These surfaces were compared to unmodified tissue culture polystyrene (PS −). The kinetics of attachment and the force of attachment using the rotating disc were determined as a function of surface and substrate protein applied to the surface. Four proteins—fibronectin, collagen I/III, collagen IV/V, and laminin—were added and compared to saline pretreatment. The most significant variable affecting attachment was the time of incubation. When corrected for time, PET + demonstrated significantly superior attachment kinetics when compared to PET − in most cases. These kinetics were similar to those seen on PS−. Fibronectin precoating of the surface greatly enhanced attachment kinetics on PET + and PS− but to a much lesser degree on PET−. The fibronectin effect was synergistic with PDSM, suggesting that PDSM enhances protein adsorption on the surface. The force of attachment was generally independent of incubation time and surface/substrate combination except for laminin precoating. Taken together, these data indicate that human endothelial cell adherence to PET may be significantly enhanced by PDSM and surface precoating with fibronectin. Attachment occurs rapidly and, once attached, the cells demonstrate a very firm attachment force capable of resisting shear stresses up to 90 dynes/cm2.
Interaction of human serum lipoproteins with biomaterials
Authors: Jayakumari N. , Chitra M. , Iyer K. Subramonia 
Published: December 2004

AbstractHuman serum was incubated with representative portions of polyvinyl chloride (PVC) blood storage bags and vascular prostheses. The in vitro interaction process with lipo‐protein was followed by polyacrylamide gel electrophoresis (PAGE) using sudan black and nitroblue tetrazolium (NBT) in the prestaining procedure. Densitometric scan of all the lipoprotein bands in serum after incubation with PVC bag material when prestained with sudan black showed remarkable increase in intensity. However, in the same experiment when NBT was used for prestaining no increase in the intensity of any of the lipoprotein bands could be observed. Since sudan black is known to bind cholesterol specifically we suggest that a molecular unfolding occurs when lipoprotein interacts with PVC bag material. When similar experiments were carried out with vascular prosthesis there was conspicuous decrease in the intensity of the high‐density lipoprotein (HDL) band especially when stained with NBT. This indicates preferential adhesion of HDL during interaction with vascular prosthesis.
Study of the osteoconductive properties of bioactive glass fibers
Authors: Pazzaglia Ugo E. , Gabbi C. , Locardi B. , Di Nucci A. , Zatti G. , Cherubino P. 
Published: December 2004

AbstractBioactive glass fibers have been prepared and implanted in cortical defect and in muscle. The fibers can act as a substrate for bone apposition, when implanted in a cortical defect, and become incorporated in the new bone matrix. The same results were obtained when fibers were implanted in a muscle pouch together with bone marrow cells. An intense inflammatory reaction was observed when bioactive glass fibers were implanted in muscle; the reaction was milder when fibers were implanted in bone or in muscle together with bone marrow cells. This fact supports the hypothesis that osteogenic cells adhere in an early phase to the substrate and prevent recognition of the foreign material by inflammatory cells. This appears to be a fundamental condition for direct bone matrix apposition on the surface of fibers.
Amphiphilic networks: II. Biocompatibility and controlled drug release of poly[isobutylene‐co‐2‐(dimethylamino)ethyl methacrylate]
Authors: Chen Dianja , Kennedy Joseph P. , Kory Martha M. , Ely Daniel L. 
Published: December 2004

AbstractBiocompatibility and diffusional characteristics of recently synthesized unique amphiphilic newtworks, i.e., copolymers of methaycryloyl‐capped polysiobutylene (MA‐PIB‐MA) with 2‐(dimethylamino)‐ethyl methacrylate (DMAEMA) have been examined. Excellent biocompatibility and biostability were obtained after 7 weeks with films containing 53–58% MA‐PIB‐MA implanted dorsally or abdominally in rats. In contras, neworks with higher or lower MA‐PIB‐MA contents showed decreased biocompatibility. These amphiphilic networks were also studied as potential implantable drug release systems. Bromophenol blue and folic acid were used as model compounds for drug release. Diffusion of these chemicals from loaded networks into water showed a marked pH dependence. Under specific well‐defined conditions (MA‐PIB‐MA/DMAEMA content, pH, time range) release was observed to be independent of time (zero‐order release).
Desorption and exchange properties of adsorbed albumin on apatite. Influence of long‐term interfacial residence times
Authors: Mura M. J. , Behr S. , Voegel J. C. 
Published: December 2004

AbstractA technique using 125‐I‐labeled proteins was employed to study static adsorption properties and slow exchange and desorption processes of human albumin in contact with synthetic hydroxyapatite beads. With the aid of a thermostated “minicolumn,” the adsorption isotherm was obtained during a so‐called multiadsorption process, and could be described by a Langmuir adsorption model (K = 1.10 × 1010 cm3 · mol−1). All kinetic desorption and exchange experiments could be fitted by a simple exponential function of time. No influence of long‐term interfacial residence times on characteristic relaxation times or percentage of desorbed or exchanged proteins could be detected in the present system. On the other hand, as compared to the low surface coverage domain, the small percentage of desorbable and high percentage of exchangeable molecules in the adsorption plateau domain was attributed to a bimolecular exchange process.
Effects of synthetic calcium phosphates on the 3h‐thymidine incorporation and alkaline phosphatase activity of human fibroblasts in culture
Authors: Orly I. , Grégoire M. , Menanteau J. , Dard M. 
Published: December 2004

AbstractGingival fibroblasts were cultured with four different calcium phosphate minerals (hydroxyapatite, whitlockite, b̃‐tricalcium phosphate, and octocalcium phosphate). 3H‐thymidine incorporation into DNA and alkaline phosphatase specific activity were determined after different incubation periods. As a consequence of the phagocytosis of calcium phosphates crystals, we pointed out, compared to control, a stimulation of the rate of 3H‐thymidine incorporation and sharp decreases in alkaline phosphatase activity. The magnitude of the alkaline phosphatase activity inhibition was observed to be increased with the solubility of the materials. We propose that the effects of calcium phosphates on alkaline phosphatase and 3H‐thymidine incorporation could be calcium‐mediated events, resulting from intracellular dissolution of phagocytized materials. We suggest that in vitro determination of 3H‐thymidine incorporation and alkaline phosphatase activity, which are highly sensitive tests, could be involved in evaluation procedures of calcium phosphates biomaterials.
Immobilization and characterization of β‐galactosidase in thermally reversible hydrogel beads
Authors: Park Tae Gwan , Hoffman Allan S. 
Published: December 2004

Abstractβ‐Galactosidase has been immobilized within thermally reversible hydrogel beads and has been studied in batch and packed bed reactor systems. The enzyme was entrapped in a copolymer hydrogel of N‐isopropylacrylamide (NIPAAm) and acrylamide (AAm) as beads were formed in an inverse suspension polymerization. A reversible deswelling and reswelling of the hydrogel matrix was induced by first warming and then cooling through 37–40°C, which is the lower critical solution temperature, LCST, of the backbone copolymer. The optimum temperature for maximum activity of the immobilized enzyme‐gel bead system was found to be 30–357deg;C in a batch mode and 40°C in a packed bed reactor, which were both below the 50°C optimum for the free enzyme. These differences are understandable, since the mass transfer rates of substrate and product within the pores of the gel matrix are controlled mainly by the temperature, so therefore it is the temperature which governs the overall activity of the immobilized enzyme system. It was also found that when the operational temperature in the packed bed reactor was cycled between temperatures below (35°C) and above (45°C) the copolymer gel LCST, the activity of the immobilized enzyme almost fully recovered after each cycle. In fact, the enzyme‐gel system exhibited a complete “shut‐off” in activity at 50°C which was the temperature where the free enzyme showed its maximum activity. The thermal cycling operation of LCST enzyme‐gel beads can be used to enhance overall activity and productivity of a packed bed reactor, when compared to isothermal operation of this reactor. This is due to the thermally induced “pumping” which enhances mass transfer rates of substrate in and product out of the gel beads.
Sepsis of vascular catheters. II: In vitro disinfection of colonized tubing
Authors: Dennis Melvin B. , Jones Douglas R. , Tenover Fred C. 
Published: December 2004

AbstractPreparatory to development of in situ disinfection of implanted catheters, silicone rubber tubing colonized by incubation with Staphylococcus aureus, Staphylococcus epidermidis, or Klebsiella pneumoniae was used to test the efficacy of various chemicals in vitro. Protocols sterilizing all segments colonized for 24 h (n = 30) were immersion into 50% povidone iodine for 5 and 60 min, 100% povidone iodine for 5, 15, and 60 min, 1.2 × 103 ppm chlorine dioxide for 15 and 60 min, and 1.2 × 103 ppm chlorine dioxide buffered to pH 5.1 for 60 min. Immersion in up to 2% chlorhexidine, 7.4% formaldehyde, or 6% sodium hypochlorite for up to 60 min failed to sterilize all segments. None of 117 control segments were sterilized. Segments colonized for seven days were sterilized by immersion into 100% povidone iodine for 15 or 60 min. Use of 1.2 × 103 ppm chlorine dioxide for 60 min sterilized 97% of segments tested. Lower concentrations and shorter exposure times failed to sterilize all segments. Eighteen silicone rubber catheters, colonized on the outer surface, were all sterilized within 24 h by a chlorine dioxide solution placed in the lumen and diffusing through the wall to kill the bacteria.
The influence of calcium phosphate biomaterials on human bone cell activities. An in vitro approach
Authors: Grégoire M. , Orly I. , Menanteau J. 
Published: December 2004

AbstractAn in vitro method is described to assess the influence of synthetic calcium phosphate powders on osteoblast activities. Human osteoblast cell cultures were established from iliac crest. MC3T3‐E1, an established osteogenic cell line, was employed as a control. Scanning and transmission electron microscopic observations clearly demonstrated the internalization of particles of calcium phosphate by the two osteoblast cell populations. As a consequence to the phagocytotic process, RNA transcription and protein synthesis were stimulated, as indicated by the measurements of labeled uridine, leucine and proline uptakes. From these data, it is proposed that such an in vitro model, using one of the specific cell types involved in the tissue responses to implants, could be useful to assess the biological response at the cell–biomaterial interaction.
Preparation of spherical encapsulation of activated carbons and their adsorption capacity of typical uremic toxins
Authors: Lee Chau‐Jen , Hsu Shih‐Tong 
Published: December 2004

AbstractA method has been designed for making spherical microencapsulation of activatedcarbon particles for use in the removal of metabolic wastes and/or toxins from blood. This bench‐scale method was able to make better uniformity in particle size, and at a higher particle production rate. The material properties such as particle size, particle porosity, electromicroscopy of surface morphology, surface hardness, and pore‐size distribution were characterized in order to conclude with their adsorption capacity for specific toxin solutes. The performance characteristics of these self‐prepared particle encapsulation was also evaluated against the commercially available hemoperfusion particles, e.g., Kuraray's DHP (Japan). The encapsulation particles were also coated with polyhydroxyethyl methacrylate (PHEMA) for blood compatibility purpose.
The histological effects of the implantation of different sizes of polyethylene particles in the rabbit tibia
Authors: Goodman S. B. , Fornasier V. L. , Lee J. , Kei J. 
Published: December 2004

AbstractThis study examines the histological effects of different sizes of polyethylene particles implanted into the rabbit tibia. Seventeen mature New Zealand white female rabbits were allocated into three groups. Group 1 (5 rabbits) received polyethylene particles averaging approximately 16 μm in diameter, implanted into the right proximal tibia through a drill hole. Group 2 (5 animals) received particles averaging 26 μm, and Group 3 (7 rabbits) received particles averaging 67 μm. The left tibia was drilled but not implanted. Animals were sacrificed after 16 weeks. Histological analysis disclosed decreased hematopoietic activity within the left tibial drill hole. In all groups, the right tibia demonstrated positively birefringent polyethylene particles surrounded by, and within (smaller particles), histiocytes and giant cells in a fibrous tissue stroma. Statistical analysis disclosed more fibrocytes and less marrow cells at the interface of Group 3 (largest particles) compared to Group 1 and 2. Larger polyethylene particles, being less readily phagocytosed, appear to produce more fibrous encapsulation, compared to particles of a smaller size. The histological reaction stimulated by the different sizes of polyethylene particles resembled the membrane surrounding loose joint arthroplasties in humans.
Stiffness and strength tailoring of a hip prosthesis made of advanced composite materials
Authors: Chang Fu‐Kuo , Perez Jose Luis , Davidson James A. 
Published: December 2004

AbstractThis work is concerned with the design of hip prostheses using advanced fiber reinforced composite materials. The major focus of the study is to evaluate how the stiffness and strength of composite hip prostheses can be affected by variations in ply orientation and stacking sequence for a selected manufacturing method. This investigation involved both analytical and experimental work. An analytical model was developed which consists of a stress analysis and a failure analysis. A finite element program was developed during the course of the investigation for analyzing stresses, strains, and deformations of composite stems with a simplified configuration. Failure and mode of failure were predicted by appropriately selected failure criteria. Experiments were also performed on T300/976 graphite/epoxy composites to verify the analysis and the computer calculations. Both testing and analysis accounted for the various combinations of in‐plane and out‐of‐plane (torsion) loading that can act on the prosthetic hip. Simplified composite stems with a 120 layer thickness were fabricated and tested. An excellent agreement was found between the measured strain data and the numerical calculations. Using the program, parametric studies were performed. It was found that an optimal design of hip stems can be achieved by using advanced fiberreinforced composite materials, but great care must be taken when selecting the appropriate ply orientation and stacking sequence for a chosen fabrication method.
In vitro and in vivo studies of heparinized‐collageno‐elastic tubes
Authors: Senatore Fred , Shankar Hariharan , Chen Jyh‐Herng , Avantsa Srinivas , Feola Mario , Posteraro Robert , Blackwell Eric 
Published: December 2004

AbstractHeparin was covalently coupled to collageno‐elastic grafts (CET) derived from lamb carotid arteries, by using the crosslinking agent 1‐ethyl‐3 (3‐dimethylaminopropyl) carbodiimide (EDC). The collagenous grafts were pretreated with various aminating agents in order to enhance the number of available binding sites on the collagen surface. By varying the EDC/heparin weight ratio, the pH of the immobilization media, and the pretreatment agent, a global search pattern maximized heparin loading at 3.90 ± 0.36 USP heparin/cm2 collagenous graft surface when the EDC/heparin ratio was 2:1 at a pH of 1.5 with 1 M hydroxylamine sulfate as the pretreatment agent. Heparinized CETs were superior to nonheparinized CETs by exhibiting both enhanced antiplatelet activity in using an in vitro differential recirculation reactor with chromium‐51 tagged platelets and enhanced patency when interposed in canine carotid arteries. Both antiplatelet activity and patency duration for heparinized CETs were independent of heparin loading.
Preparation and evaluation of radiopaque hydrogel microspheres based on PHEMA/iothalamic acid and PHEMA/iopanoic acid as particulate emboli
Authors: Jayakrishnan A. , Thanoo B. Chithambara , Rathinam K. , Mohanty M. 
Published: December 2004

AbstractHighly porous poly(2‐hydroxyethyl methacrylate) (PHEMA) microspheres prepared by suspension polymerization of 2‐hydroxyethyl methacrylate (HEMA) in presence of polymeric diluents such as poly(methyl methacrylate) (PMMA) in toluene and poly(tetramethylene glycol) (PTMG) were made radiopaque by esterification of the reactive hydroxyl groups with iothalamic acid and iopanoic acid, two radiopaque substances clinically used. Of the various solvents and catalysts examined, tetrahydrofuran (THF) and N,N′‐dimethyl paratoluidine (DMPT) were found to be best for obtaining a high degree of conversion. More than 30 wt% iodine could be bound to the microspheres which made them sufficiently radiopaque to be imaged radiographically. Microspheres retained their porosity, swelling ability, hydrophilicity, and surface morphology to a significant extent after iodination. Preliminary implantation studies of such microspheres subcutaneously in rats have shown no adverse tissue reactions over a 6‐month period. It is suggested that these microspheres would prove to be useful as particulate emboli in endovascular embolization.
Adhesive bonding of denture base resins to plastic denture teeth
Authors: Suzuki Shiro , Sakoh Mitsuo , Shiba Akihiko 
Published: December 2004

AbstractThe adhesive bonding of denture teeth to denture base resins in dentures with conventional acrylic teeth and crosslinked plastic teeth was investigated. The dentures with highly crosslinked plastic teeth such as SR‐Orthosit, Crystal ND, and Mitel‐OM showed poor bonding at the tooth/base resin interface using the conventional bonding method. Elimination of the alginate mold lining material in the conventional bonding method effectively improved bonding at the tooth/base resin interface. The application of 4‐META adhesive bonding agents to the denture teeth improved the interface bonding of highly crosslinked plastic teeth and the denture base. Dentures with Orthosit and Mitel showed differences in bonding ability when two different adhesives were used.
The effect of glass‐ceramic implants on matrix vesicle calcification after two weeks of rat tibial bone healing
Authors: Müller‐Mai C. , Amir D. , Wendland H. , Schwartz Z. , Sela J. , Gross U. 
Published: December 2004

AbstractType, size and distribution of extracellular matrix vesicles (MV), known mediators of primary calcification, were studied around bone‐bonding and metal‐oxide containing, nonbonding, glass‐ceramic implants. This was performed in order to further understand the different effects of implants on bone healing. At 14 days after implantation in adult rat tibial bone the effects of different implants on MV were studied by transmission electron microscopy and computerized morphometry. A total number of 4607 MV in 245 electron micrographs were counted and grouped according to diameter, distance from the calcifying front, and classified as four types: “empty,” “amorphous,” “crystal,” and “rupture.” The sequence of types according to diameter and distance was recorded as follows around both implants tested: “rupture” MV were the closest to the front with the largest diameter, followed by “crystal,” “amorphous,” and “empty,” MV with the largest distance from the front and the smallest diameter. Most vesicles were concentrated in a distance of less than 2.4 μm from the front and between diameters of 0.06 μm and 0.22 μm. The noncalcified extracellular matrix around bone‐bonding implants contained more MV than the matrix around the nonbonding type (26.24 MV/10 μm2 and 18.76 MV/10μm2). MV distribution according to type showed that around bonding implants ther was a higher percentage of “crystal” and a lower percent age of “rupture” when compared to the nonbonding type. These results indicate that bonding implansts affect osteoblastic function by increasing tht vesicular number and retardation of intravesicular crystal fromation. It might be suggested that bonding implants induce an increase in the process of primary calcification and a decreased rate of crystal formation resulting with the highest organization of the healing bone.
Compositional analysis of biomer
Authors: Belisle Jon , Maier Susan K. , Tucker Joseph A. 
Published: December 2004

AbstractBiomer, a segmented polyether polyurethane, has been analyzed via hydrolysis/gas chromatography to determine its composition. In addition to the previously reported 4,4′‐methylene bis(phenyl isocyanate) (MDI), polytetramethylene glycol (PTMO), and ethylenediamine, we now report the presence of diethylamine, 1,3‐diaminocyclohexane and poly(diisopropylaminoethyl methacrylate‐co‐decyl methacrylate), Biomer's cloudy insoluble phase. In addition, a method is presented to characterize the methacrylate additive by molecular weight based on GPC. Also found by chromatography were the antioxidants Santowhite Powder and BHT. XPS shows no Si (silicone) on the Biomer surface, and a total chloride analysis reports no chloride (<0.03%). Time‐of‐flight SIMS data suggest evidence for the methacrylate additive at the surface, and mass spectroscopy can be interpreted as evidence for a diaminocyclohexane.