摘要:

AbstractTo evaluate an experimental inorganicbone‐particle‐impregnated bone cement, canine hip prostheses were implanted in dogs using a regular bone cement on one side and the experimental bone cement on the other. In a preliminary feasibility study, bone ingrowth into the resorbed bone‐particle spaces was established 3 months after implantation in three dogs. In a more detailed study, twenty‐eight (28) dogs were divided in four groups to delineate the effects of time on the phenomena of bony ingrowth. One month after implantation, active bone ingrowth into the bone cement was obvious. By 3 months postimplantation, the ingrowth appeared to have traversed the thickness of the bone‐particle‐impregnated cement. By the fifth month, most of the interconnected inorganic bone particles were replaced by new bone. At the end of a year, the ingrown bone was mature and negligible new bone activity was present. Biomechanical pushout tests closely corroborated the histologic observations. The maximum shear strength of the cement/bone interface of the experimental side reached 3.6 times that of the control side at 5 months postimplantation. No further improvements were seen at 12 months postimplantation. A viable bone/cement interface may result in a better orthopedic implant fixation system by combining the advantages of both cement for immediate rigidity and biological ingrowth for longter

ISSN:0021-9304    

DOI:10.1002/jbm.820250202

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractFor the purpose of studying its applicability for acrylic cement removal during total hip revision surgery, experiments with an extracorporeal shock wave lithotriptor were carried out. High‐energy shock waves (HESW) were focussed on discs of polymethylmethacrylate bone cement. The average discharge was 18.1 kV; the number of shock waves 0, 100, 250, 500, 1000, and 2000; the application rate was 85 shocks/min. Macroscopic or radiographic effects were not in evidence. Microscopically, typical lesions in a small concentric focal area with a diameter of 8.5 (± 2.5) mm were found. The individual lesions were smaller than 0.1 mm, and displayed characteristic shapes. The area porosity increased with the number of shocks. The maximal area porosity caused by the HESW, measured by quantitative microscopy, was 4% after 2000 shock waves. The lesions were also studied by scanning electron microscopy. It can be concluded that HESW causes only microscopic lesions on the frontal surface of discs of bone cement, and that these lesions are small compared to the pores normally present in bone cement, when applied clinical

ISSN:0021-9304    

DOI:10.1002/jbm.820250203

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

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‐im

ISSN:0021-9304    

DOI:10.1002/jbm.820250204

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820250205

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe adhesion and detachment of platelets were studied on glass coatings of a series of copolymers of hydroxyethyl methacrylate (HEMA) and ethyl methacrylate (EMA). Observations of the interactions of mepacrine labelled washed platelets with these surfaces from a flowing (500 s−1wall shear rate) suspension in Tyrode's solution containing albumin and red cells were made with epifluorescent video microscopy (EVM). Total platelet adhesion, including platelets which adhere on first contact and platelets which attach temporarily before adhesion, and the number of detaching platelets were minimal for the 0 and 20% EMA copolymers, reached a maximum for the 50% EMA copolymer and showed reduced values for the 80% and 100% EMA copolymers. For the 50, 80, and 100% EMA copolymers, the adhesion values expressed, as a percentage of total contacting platelets, were not different. Albumin adsorption to these copolymers shows a continuous increase from the 0% to the 100% EMA copolymer. It is likely that the peak in platelet adhesion at the 50% EMA composition is related to: low protein adsorption on the 0 and 20% EMA copolymers, too little albumin adsorption to block adhesion on the 50% EMA copolymer, and full‐scale blocking on the 80 and 100% EMA copolymers due to greater albumin adsorpt

ISSN:0021-9304    

DOI:10.1002/jbm.820250206

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

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 augmentin vitroplatelet 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 procedur

ISSN:0021-9304    

DOI:10.1002/jbm.820250207

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractPolyfunctional silanes were designed to promote the formation of a stable multisilane layer on the silica surface. The hydrolytic stability of polyfunctional silanes at the interface between silica and polymeric resin was investigated using conventional tensile testing. The specimens were immersed in boiling water and a decrease was observed in the tensile bonding strength of polymeric resin against the silane‐treated silica surface as the immersion time increased. The failure mechanism changes from cohesive failure of the matrix resin to failure of the interface. The time necessary to start the interfacial failure is dependent on the silane concentration in the treating solution and the number of silicone functional groups within the silane molecules. The silane with two silicone functional groups is more stable at the interface between silica and polymeric resin than those which have mono‐ or trisilicone functional gro

ISSN:0021-9304    

DOI:10.1002/jbm.820250208

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

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/cm2on glycophase glass, 139 fmol/cm2on PET‐OH, and 31 fmol/cm2on 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 t

ISSN:0021-9304    

DOI:10.1002/jbm.820250209

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractTwo types of liquid crystal (LC)‐entrapped membranes, (a) polymer alloyed membranes and (b) LC‐adsorbed membranes, were investigated for the purpose of developing the drug delivery systems (DDS) with thermal stimuli responsing. Polymer alloyed membranes were obtained by polymerizing acrylic monomers in presence of LC and LC‐adsorbed membrane were obtained by adsorbing LC into porous hydrophobic polymer membrane. It was made clear from the indomethacin permeation experiments below and above the gel‐liquid crystal phase transition temperature of the LC that the extent of thermo‐sensitivity for LC‐adsorbed membranes was greater than that for the alloyed membrane. The permeability ratio (38°C vs. 32°C) was found to be about 120 with the LC‐adsorbed membrane. It was suggested from the results that the LC‐adsorbed membrane was one of the useful candidates as a thermo‐respon

ISSN:0021-9304    

DOI:10.1002/jbm.820250210

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820250211

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY