bluuebunny/crossref_metadata_2025_split huggingface dataset:
Marrow cell induced osteogenesis in porous hydroxyapatite and tricalcium phosphate: A comparative histomorphometric study of ectopic bone formation
Authors: Ohgushi Hajime , Okumura Motoaki , Tamai Susumu , Shors Edwin C. , Caplan Arnold I. 
Published: December 2004

AbstractTo investigate the bone formation ability of porous hydroxyapatite (HA) and tricalcium phosphate (TCP), ceramic discs were implanted with or without rat marrow cells into subcutaneous sites in syngeneic rats. The discs of HA and TCP had identical microstructures: pore size was 190–230 μm, porosity was 50–60%, and they were fully interconnected. Implants without marrow cells (discs themselves) did not show bone formation, whereas implants with marrow cells showed bone formation in the pores of the ceramics. The bone formation of both HA and TCP occurred initially on the surface of the ceramic and progressed towards the center of the pore. The de novo bone was quantitated from decalcified serial sections of the implants. One month after implantation with marrow cells, the percentage fractions of the pore area filled with bone for implanted HA and TCP were 16.9 and 15.1, respectively. At 2 months after implantation with marrow cells, the fractions of bone were 34.3 and 30.9, respectively. These results indicate that both HA and TCP ceramics can show comparable osteogenic ability in the presence of marrow cells.
A histomorphological study on self‐reinforced polyglycolide (SR‐PGA) osteosynthesis implants coated with slowly absorbable polymers
Authors: Vasenius Jarkko , Vainionpää Seppo , Vihtonen Kimmo , Mero Matti , Mäkelä Antero , Törmälä Pertti , Rokkanen Pentti 
Published: December 2004

AbstractA total of 150 osteotomies of rabbits' distal femur were fixed with absorbable self‐reinforced polyglycolide (SR‐PGA) rods coated with slowly absorbable polymers. In order to reduce the degradation rate of the SR‐PGA construction rods were coated with n‐butyl‐2‐cyanoacrylate, polydioxanone (PDS), poly‐beta‐hydroxybutyrate (PHBA), or poly‐l‐lactide (PLLA). Biocompatibility and the rate of biodegradation were evaluated in histological, histomorphometric, microradiographic, and oxytetracycline labeling studies. PDS, PHBA, and PLLA coatings showed good biocompatibility although there were scattered fluid accumulations around the rod in each group. Cyanoacrylate coating seemed to inhibit cartilage regeneration and cause the formation of considerable amount of connective tissue around the implant. The PGA core of the rod had totally degraded in 24 to 36 weeks in each coating group. Cyanoacrylate and PDS coatings were not detectable after 6 weeks while PHBA and PLLA coatings were still observed after 48 weeks. There were five (14%) non‐unions in the cyanoacrylate coating group, one (3%) in the PHBA coating group caused by a purulent infection and none in the PDS and PLLA coating groups.
Radiofrequency plasma deposition of oxygen‐containing films on polystyrene and poly(ethylene terephthalate) substrates improves endothelial cell growth
Authors: Ertel Sylvie I. , Ratner Buddy D. , Horbett Thomas A. 
Published: December 2004

AbstractPolystyrene and poly(ethylene terephthalate) substrates were modified by radiofrequency plasma deposition with organic vapors comprised of carbon, oxygen, and hydrogen (acetone, methanol, glutaraldehyde, formic acid, allyl alcohol, and ethylene oxide). The treatments resulted in the deposition of a film at least 100 Å thick containing up to 26% atomic oxygen at the surface. A high oxygen incorporation was observed for vapors with a large oxygen‐to‐carbon ratio. Bovine aortic endothelial cell growth measured on acetone, methanol, and glutaraldehyde films was linearly correlated with the oxygen content of the treated surfaces. Nitrogen was incorporated in the surface by blending nitrogen gas into the organic vapors used for plasma deposition. The resulting nitrogen‐containing substrates exhibited a high affinity for serum fibronectin but a moderate cell growth.
Ultra‐high‐strength absorbable self‐reinforced polyglycolide (SR‐PGA) composite rods for internal fixation of bone fractures: In vitro and in vivo study
Authors: Törmälä P. , Vasenius J. , Vainionpää S. , Laiho J. , Pohjonen T. , Rokkanen P. 
Published: December 2004

AbstractThe ultra‐high‐strength, self‐reinforced (SR) absorbable polymeric composites, consisting of reinforcement elements, like fibers, and of matrix polymer which have the same chemical element composition as reinforcement, were defined. A method to manufacture self‐reinforced, absorbable polyglycolide (SR‐PGA) rods of polyglycolide sutures (Dexon) by sintering them partially together at elevated temperature and pressure was presented. The rods with nominal diameters of 1.5 mm, 2.0 mm, 3.2 mm, and 4.5 mm showed initial bending modulus and strength values of 8–15 GPa and 220–405 MPa, respectively. Their initial shear strengths were 165–255 MPa. The smallest rods (diam. 1.5 mm) lost their mechanical strength after implantation in the subcutis of rabbits in 4–5 weeks while the thickest rods retained their strength over 8 weeks. The ultra‐high‐strength SR‐PGA rods were concluded to be suitable for fixation of cancellous bone fractures, osteotomies, and epiphyseal plate fractures where the fixation is not exposed to excessive mechanical stresses and where the loads are predominantly of a shear nature.
Calcium phosphate materials containing alumina: Raman spectroscopical, histological, and ultrastructural study
Authors: Bertoluzza A. , Simoni R. , Tinti A. , Morocutti M. , Ottani V. , Ruggeri A. 
Published: December 2004

AbstractVariable alumina quantities were added to two types of calcium phosphate materials–hydroxyapatite ceramics with Ca/P = 1.67 and calcium metaphosphate glass with Ca/P = 1–in order to increase their mechanical properties. Raman spectroscopy shows that alumina interacts with the phosphate group of these materials, while thermomechanical analysis shows that their elastic modulus has a value similar to that of bone. Histological sections demonstrate that the surface in close contact with ceramic materials shows a good integration between bone and biomaterial. All ceramic specimens are penetrated by well‐stained, presumably glycoprotein, matrix, that consistently forms a thin network in close contact with the implant. After 6 weeks bone growing on both ceramic and glass shows signs of maturation with a lamellar structure and an apparently normal mineralization. In the case of the glass, inside this newly formed bone, were often observed two layers, the internal one showing a well defined lamellar structure.
Fibrin–antibiotic mixtures: An in vitro study assessing the possibility of using a biologic carrier for local drug delivery
Authors: Greco F. , de Palma L. , Spagnolo N. , Rossi A. , Specchia N. , Gigante A. 
Published: December 2004

AbstractAn in vitro study assessing the kinetics of drug release from antibiotic–fibrin seal compounds and the antibacterial efficacy of the delivered drug has been performed. Antibiotic sensitivity and the amount of drug released was measured by means of agar diffusion test. Standard and experimental curves were established for each antibiotic and each bacterial test in order to evaluate the quantities of the drug released during each 24 h period. The reconstitution of lyophilized human fibrin with an aqueous solution containing an antibiotic resulted in only minor modification of the clotting process, with the exception of those solutions containing cefotaxim and mezlocillin which failed to clot altogether and were excluded from further study. The evaluation of the kinetics of elution of the antibiotics from the fibrin clots showed that all of the antibiotics had been almost completely released by 96 h. The delivered amount of each drug was enough to maintain the Minimal Inhibitory Concentration (MIC) until the 4th day of culture for the most of antibiotics, resulting in a prolonged release of the drug.
Plasma‐sprayed coatings of tetracalciumphosphate, hydroxyl‐apatite, and α‐TCP on titanium alloy: An interface study
Authors: Klein Christel P. A. T. , Patka P. , van der Lubbe H. B. M. , Wolke J. G. C. , de Groot K. 
Published: December 2004

AbstractIn order to study the interaction of calcium phosphate coatings with bone tissue, coated titanium cylinders with a standard size were implanted in dog femora. Coatings were made by plasma spraying powders of hydroxylapatite, β‐whitlockite, and tetracalciumphosphate particles. The plasma spraying process tuns β‐whitlockite into α‐TCP. Bone bonding and bone formation were evaluated by mechanical push‐out tests and histological observations. Hydroxylapatite and tetracalciumphosphate coatings show an interface strength after 3 months of implantation of 34.3 ± 6.5 MPa and 26.8 ± 3.9 MPa, respectively, while α‐TCP and blanco titanium lead to an interface strength of 10.0 ± 3.5 MPa and 9.7 ± 1.3 MPa, respectively. Histological examinations revealed that hydroxylapatite and tetracalciumphosphate give rise to an excellent bone formation, while α‐TCP and blanco titanium evoked remodeling and less bone contact.
Interaction of poly(sodium vinyl sulfonate) and its surface graft with antithrombin III
Authors: Ito Yoshihiro , Liu Lin‐Shu , Imanishi Yukio 
Published: December 2004

AbstractPoly(sodium vinyl sulfonate) (PVS) was found to be 1/14 times as active as heparin in inducing the conformational change and activation of antithrombin III. The conformational change of antithrombin III was investigated in terms of the intrinsic fluorescence of tryptophan residue, the extrinsic fluorescence using 1,6‐diphenyl‐1,3,5‐hexatriene as fluorescent probe, and Fourier‐transform infrared spectroscopy. It was evident in the experiment using 2,4,6‐trinitrobenzene sulfonate that PVS elicited the activity of antithrombin III by interacting with amino groups of the protein as does heparin.Sodium vinyl sulfonate was graft‐polymerized onto polyetherurethane (PEU) film that was treated with glow discharge in advance. PVS‐grafted PEU film adsorbed antithrombin III easily and, like ungrafted PVS, induced conformational change and activation of antithrombin III. However, the mechanism of interaction of the PVS graft with antithrombin III did not seem to be completely the same as that of ungrafted PVS in solution.
Fibroblast stimulation by monocytes cultured on protein adsorbed biomedical polymers. I. Biomer and polydimethylsiloxane
Authors: Bonfield T. L. , Colton E. , Anderson J. M. 
Published: December 2004

AbstractThe studies presented in this paper evaluate the modulatory role of protein preadsorbed polydimethylsiloxane (PDMS) and Biomer on the secretion of fibroblast stimulating growth factors from human monocytes/macrophages. The results of these studies show that Biomer and PDMS selectively activate human monocytes to produce fibroblast “progression‐like” and to a lesser extent “competence‐like” stimulating growth factors. Polydimethylsiloxane stimulated the monocytes/macrophages to produce more “progression‐like” fibro‐blast stimulating growth factors than Biomer. The induction of “competencelike” fibroblast stimulating activity from the monocytes was enhanced by preadsorption of PDMS with human derived fibrinogen, fibronectin, IgG, hemoglobin, or albumin. This phenomenon was not observed with protein preadsorbed Biomer. These studies support the hypothesis that protein preadsorbed polymers will selectively modulate monocyte/macrophage activation and induction of growth factors which have the potential to participate in tissue‐implant interactions in vivo.
Improved biocompatability of silicone rubber by removal of surface entrapped air nuclei
Authors: Kalman P. G. , Ward C. A. , McKeown N. B. , McCullough D. , Romaschin A. D. 
Published: December 2004

AbstractBiomaterials activate the complement system which is important since C3a promotes platelet aggregation and release, and C5a activates neutrophils that may augment coagulation. Tiny air nuclei (microbubbles) are found in the surface roughness of biomaterials on exposure to a liquid, therefore two interfaces exist: (a) a blood/biomaterial, and (b) a blood/air interface. Experiments were carried out that documented that air bubbles activate complement and augment in vitro platelet aggregation in human plasma. The air nuclei were removed from the surface of silicone rubber by a technique termed denucleation to determine if complement activation and platelet aggregation could be reduced. We observed a significant reduction in C3a and C5a in the plasma samples incubated with denucleated silicone rubber as compared to the control samples (p < 0.001, ANOVA). The plasma incubated with the denucleated silicone caused reduced platelet aggregation as compared to the plasma incubated with the control silicone when added to a platelet suspension (p < 0.001, ANOVA). Surface chemical analysis by x‐ray photoelectron spectroscopy (XPS) showed no change in the silicone rubber surface after the denucleation procedure.
Human endothelial cell interactions with surface‐coupled adhesion peptides on a nonadhesive glass substrate and two polymeric biomaterials
Authors: Massia S. P. , Hubbell J. A. 
Published: December 2004

AbstractThe attachment, spreading, spreading rate, focal contact formation, and cytoskeletal organization of human umbilical vein endothelial cells (HUVECs) were investigated on substrates that had been covalently grafted with the cell adhesion peptides Arg‐Gly‐Asp (RGD) and Tyr‐Ile‐Gly‐Ser‐Arg (YIGSR). This approach was used to provide substrates that were adhesive to cells even in the absence of serum proteins and with no prior pretreatment of the surface with proteins of the cell adhesion molecule (CAM) family. This approach was used to dramatically enhance the cell‐adhesiveness of substrates that were otherwise cell‐nonadhesive and to improve control of cellular interactions with cell‐adhesive materials by providing stably bound adhesion ligands. Glycophase glass was examined as a model cell‐nonadhesive substrate prior to modification, and polyethylene terephthalate (PET) and polytetrafluoroethylene (PTFE) were examined as representative materials for biomedical applications. The peptides were surface‐coupled by their N‐terminal amine to surface hydroxyl moieties using tresyl chloride chemistry. Prior to peptide grafting, the PET and PTFE were surface hydroxylated to yield PETOH and PTFE‐OH. The PET‐OH was less cell‐adhesive and the PTFE‐OH was much more cell‐adhesive than the native polymers. Radioiodination of a C‐terminal tyrosine residue was used to quantify the amount of peptide coupled to the surface, and these amounts were 12.1 pmol/cm2 on glycophase glass, 139 fmol/cm2 on PET‐OH, and 31 fmol/cm2 on PTFE‐OH. Although the glycophase glass did not support adhesion or spreading even in the presence of serum, the RGD‐ and YIGSR‐grafted glycophase glass did support adhesion and spreading, even when the only serum protein that was included was albumin. Although PET and PTFE‐OH supported adhesion when incubated in serum‐supplemented medium, neither of these materials supported adhesion with only albumin present, indicating that cell adhesion is mediated by adsorbed CAM proteins. When these materials were peptide‐grafted, however, extensive adhesion and spreading did occur even when only albumin was present. Since the peptide grafting is quite easily controlled and is temporally stable, while protein adsorption is quite difficult to precisely control and is temporally dynamic, peptide grafting may be advantageous over other approaches employed to improve long‐term cell adhesion to biomaterials.
The effect of cells on biomaterial calcification: Experiments with in vivo diffusion chambers
Authors: Rosanova I. B. , Mischenko B. P. , Zaitsev V. V. , Vasin S. L. , Sevastianov V. I. 
Published: December 2004

AbstractThe results of these in vivo experiments show that bovine pericardium can undergo calcification without direct contact with tissue. It is clear that the direct interaction of cells with implanted samples both promotes and accelerates the process of calcification. Moreover, dietary calcium supplements, calcium chloride and vitamin D can intensify the rate and extent of this process.
Torsional properties of implant grade titanium
Authors: Zardiackas Lyle D. , Disegi John , Givan Daniel 
Published: December 2004

AbstractThe purpose of this research was to evaluate the torsional strength and ductility of CP titanium in the as received condition, heat treated below the α → β transition temperature, and glass bead blasted. Results were compared to as‐received samples of implant quality 316L stainless steel. Little or no effect of any of the treatments was noted. The torsional strength of all titanium samples was comparable to 316L stainless and the torsional ductility of the titanium was significantly greater than 316L stainless (p <.01). These results are significantly different than those obtained when torsion testing bone screws of the same material. A hypothesis is proposed for the differences in these results.
A new biodegradable copolymer of glycolic acid and lactones with relatively low molecular weight prepared by direct copolycondensation in the absence of catalysts
Authors: Fukuzaki Hironobu , Yoshida Masaru , Asano Masaharu , Kumakura Minoru , Mashimo Tooru , Yuasa Hisako , Imai Kyoichi , Yamanaka Hidetoshi , Kawaharada Umeko , Suzuki Keiji 
Published: December 2004

AbstractRelatively low‐molecular‐weight copolyesters of glycolic acid (GA) with lactones such as γ‐butyrolactone (BL), δ‐valerolactone (VL), and ϵ‐caprolactone (CL) were synthesized by copolycondensation without catalysts. The resulting copolyesters are intended as carriers for drug delivery systems. Copolyesters with approximately 85 mol% GA (number‐average molecular weight (Mn): 2900 ± 100) are crystalline and solid and show a parabolic‐type in vivo degradation pattern. The in vivo degradation of amorphous‐pasty poly (GA/CL) (approximately 50/50 mol%) changed from parabolic‐type to lineartype to S‐type pattern as their molecular weight increased. A luteinizing hormonereleasing hormone agonist, D‐Leu,6 desGly10 ‐LHRH ethylamide monoacetate (LHRH agonist), was incorporated into small cylinders with these copolyesters. An initial burst of LHRH agonist was observed for cylinders prepared with parabolic‐type degrading copolyesters, in contrast to a marked delay in LHRH agonist release for cylinders prepared with S‐type degrading copolyesters. The resulting daily dose of drug was maintained an approximately constant, though decreasing stepwise with time. For example, the daily amount of LHRH agonist released in vivo from a cylinder prepared with poly(GA/CL) (50/50 mol%; Mn = 4500) was 61 ± 39 μg/day throughout an experimental period of 10 weeks with a corresponding pharmacological effect on the rat prostate.
Bone‐bonding ability of P2O5‐Free CaO · SiO2 glasses
Authors: Ohura Kouichiro , Nakamura Takashi , Yamamuro Takao , Kokubo Tadashi , Ebisawa Yukihiro , Kotoura Yoshihiko , Oka Masanori 
Published: December 2004

AbstractAn apatite‐ and wollastonite‐containing glass‐ceramic (A · W‐GC) has been reported to form a tight bond with living bone through an apatite layer formed on its surface. This layer is considered to be formed by dissolution of Ca2+ and HSiO3− ions from the glass‐ceramic into the surrounding body fluids. In order to confirm this proposed mechanism for the surface reaction of A · W‐GC, three kinds of glass in the systems CaOSiO2, CaOSiO2CaF2, and CaOSiO2P2O5 were implanted into the tibiae of rabbits for 3 or 8 weeks. Contact microradiography and SEM‐EPMA showed that all three kinds of glass formed a Ca, P‐rich layer in combination with a Si‐rich layer on their surfaces within 3 weeks and formed a direct bond with bone via these layers. The detaching test, performed 8 weeks after implantation, showed that the loads required to detach the implants from the bone were almost equal for the phosphorus‐free and the phosphorus‐containing glasses. It was concluded that even P2O5‐free CaO · SiO2 glass formed a Ca,P‐rich layer on its surface and bonded tightly with living bone. If glasses and glass‐ceramics release at least Ca2+ and HSiO3− ions, this would be sufficient for them to form the Ca,P‐rich layer on their surfaces in vivo, enabling them to bond directly with bone.
Quantification of gas denucleation and thrombogenicity of vascular grafts
Authors: Bensen Christopher V. , Vann Richard D. , Koger Kim E. , Klitzman Bruce 
Published: December 2004

AbstractIn vitro methods were developed to measure the air content of vascular graft walls and the thrombogenicity of this air. Gas content (volume %) of expanded polytetrafluoroethylene (ePTFE) grafts from different sources ranged from 75.5 ± 0.4% to 61.8 ± 0.3%. Exposure of Vitagraft ePTFE to a vacuum prior to saline immersion replaced 87.5% of the gas nuclei with saline (denucleation). Acetone and ethanol immersion produced 98.9% and 94.3% denucleation, respectively. Denucleation was essentially complete when vacuum exposure was followed by hydrostatic pressure treatment at 500 psig or greater. The influence of gas content on thrombogenicity was determined by immersing graft samples in whole canine blood and weighing the adherent thrombus. Denucleation significantly reduced adherent thrombus weight compared with control grafts (p < 0.001). Air in Vitagraft walls was responsible for 84% of the adherent thrombus weight at four minutes. The described methods could be employed to assess the hemocompatibility of various biomaterials.
A light and electron microscopic study of the effects of surface topography on the behavior of cells attached to titanium‐coated percutaneous implants
Authors: Chehroudi B. , Gould T. R. L. , Brunette D. M. 
Published: December 2004

AbstractPrevious studies using light microscopy have demonstrated that micromachined grooved surfaces inhibit epithelial (E) downgrowth and affect cell orientation at the tissue/implant interface. This study investigates the ultrastructure of the epithelial and connective‐tissue attachment to titanium‐coated micromachined grooved, as well as smooth control, implant surfaces. V‐shaped grooves, 3, 10, or 22 μm deep, were produced in silicon wafers by micromachining, replicated in epoxy resin, and coated with 50‐nm titanium. These grooved, as well as smooth, titanium‐coated surfaces were implanted percutaneously in the parietal area of rats and after 7 days processed for electron microscopy. The tissue preparation technique used in this study enabled us to obtain ultrathin sections with few artifacts from the area of epithelial and connective‐tissue attachment. The histological observations demonstrated that E cells closely attached to, and interdigitated with, the 3‐μm and 10‐μm grooves. In contrast, E cells were not found inside the 22‐μm‐deep grooves and made contact only with the flat ridges between the grooves. As a general rule, fibroblasts (F) were oriented parallel to the long axis of the implants and produced a connective tissue capsule with 3‐μm and 10‐μm‐deep grooved surfaces as well as smooth surfaces. On the 22‐μm‐deep grooved surfaces, however, F inserted obliquely into the implant. The attachment of F to the titanium surface was mediated by two zones; a thin (≈︁20 nm), amorphous, electron dense zone immediately contacting the titanium surface, and a fine fibrillar zone extending from the amorphous zone to the cell membrane. As oblique orientation of F has been associated with the inhibition of epithelial downgrowth, micromachined grooved surfaces of appropriate dimensions have the potential to improve the performance of percutaneous devices.