摘要:

AbstractThe glow discharge plasma deposition (GDPD) of tetraethylene glycol dimethyl ether is introduced as a novel method for obtaining surfaces that are resistant to protein adsorption and cellular attachment. Analysis of films by x‐ray photoelectron spectroscopy and several biological assays indicate the formation of a foulingresistant, PEO‐like surface on several substrata (e.g., glass, polytetrafluoroethylene, polyethylene). Adsorption of125I‐radiolabelled proteins (fibrinogen, albumin and IgG) from buffer and plasma was very low (typically<20 ng/cm2) when compared to the untreated substrata, which exhibited much higher levels of protein adsorption. Not all coated substrata adsorbed equal amounts of protein (e.g., coated glass samples typically adsorbed more protein than coated polyethylene or coated polytetrafluoroethylene samples), suggesting that the substratum used may affect the amount of protein adsorbed. Measurement of dynamic platelet adhesion, using epifluorescent video microscopy, and endothelial cell attachment further demonstrates the short‐term nonadhesiveness of these s

ISSN:0021-9304    

DOI:10.1002/jbm.820260402

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractSurfaces of implantable and blood contact‐devices accumulate adsorbed and denatured proteins. This anomalous layer of proteins may help trigger unwanted events such as activation of coagulation systems and, perhaps, chronic inflammation. Because, in many experimental systems, the purposeful coating of surfaces with albumin will biologically “passivate” materials, we have attempted to develop polymers which, when exposed to blood or body fluids, will spontaneously, selectively, and reversibly adsorb host albumin. We report here a novel derivatization technique for increasing the albumin affinity of implantable polyetherurethane (PU). The technique is based on the incorporation of high‐molecular‐weight dextran to which the albumin‐binding dye Cibacron Blue is covalently attached. Somewhat surprisingly, the amounts of human albumin adsorbed by Blue Dextran‐modified and unmodified PU are quite similar. There are, however, important differences. First, the binding of albumin to derivatized PU is specific and not readily blocked by proteins in albumin‐depleted human serum. Second, the majority of albumin associated with derivatized PU appears to be reversibly bound. Third, the binding of albumin to derivatized PU evidently is mediated primarily through ligandspecific binding of the protein to the albumin‐binding dextran‐dye conjugate. We conclude that it is possible to produce implantable polymers having surfaces which display albumin‐binding dyes that selectively and reversibly bind albumin. Materials with this property, when implanted or exposed to blood, should form an infinitely renewable coating of albumin derived from physiologic fluids. This surface modification strategy may spawn a new generation of implantable materials with improved b

ISSN:0021-9304    

DOI:10.1002/jbm.820260403

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe studies presented in this manuscript were based upon the hypothesis that monocytes/macrophages selectively produce cytokines and growth factors due to their interactions with polymers and proteins which are adsorbed to their surfaces. These factors in turn selectively influence the ability of fibroblasts to proliferate. The factors which influence fibroblast proliferation were released from monocytes incubated with polymers: Biomer®, polydimethylsiloxane (PDMS), polyethylene (PE), expanded polytetrafluoroethylene (ePTFE), Dacron, and control polystyrene with and without preadsorption with physiological concentrations of IgG, fibrinogen, fibronectin, hemoglobin, or albumin. No simple correlation was found between adsorbed protein, biomedical polymer, and the ability monocytes to produce growth factors and cytokines which influence fibroblast proliferation. This is evidence for selective protein‐polymer interactions which turn selectively activate monocytes produce variable cell cycle competence and progression factors controlling fibroblast grow

ISSN:0021-9304    

DOI:10.1002/jbm.820260404

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe aim of preoperative embolization is to facilitate surgical removal by reducing tumor volume and vascularity, thereby decreasing blood loss during surgery. In a search for a better embolic material, compared to heterogeneous commercial products, we describe here in detail the preparation of poly (D,L) lactide microspheres by an emulsion‐solvent evaporation process. The size distribution of the microparticles and their aggregation state‐critical parameters in view of such application‐have been investigated. Their effectiveness, as an embolic material, has been evaluated by some preliminary experiments undertaken on humans. The results were assessed on clinical and histological gr

ISSN:0021-9304    

DOI:10.1002/jbm.820260405

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractVarious methods have been used for anastomosing, or attaching, two ends of a severed blood vessel together. The most common method, suturing, is tedious, can be time‐consuming, and requires special training in microvascular surgery. Other methods, such as mechanical devices and lasers, have some problems as well. The use of fibrin adhesives for blood vessel anastomosis might eliminate some of the current problems by allowing a quicker, simpler, and more reliable method of attachment. Although mechanical studies have been conducted to determine fibrin glue properties in shear, tensile, and burst tests; most of these studies have used skin or intestinal tissue. Therefore, to evaluate the feasibility of using fibrin glue as an adhesive for blood vessel anastomosis, the mechanical properties of blood vessels joined with fibrin glue were examined using tensile and burst tests. High and low fibrinogen concentrations were tested after 5‐ or 45‐min time periods. In addition, three clinical methods of attachment were compared: end‐to‐end anastomosis, vessel overlapping, and suturing. In this study, because the adhesive strength was not found to increase significantly after 5 min, setting times for fibrin glue may be short enough to make it a clinical option when compared to suturing. In addition, the higher fibrinogen concentration did not result in a significantly higher adhesive strength, indicating that the lower concentration fibrin adhesives may be of comparable strength to the higher concentrations for clinical app

ISSN:0021-9304    

DOI:10.1002/jbm.820260406

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractIdeally, the surface of epithelium‐pene‐ trating implants should impede apical epithelial migration. Previous studies have shown that micromachined grooved surfaces can produce connective‐tissue ingrowth, which inhibits epithelial downgrowth on percutaneous implants [Chehroudi et al., J. Biomed. Mater. Res., 24, 9, (1990)]. However, in those studies, connective tissue and epithelium interacted with the same surface so that the effects of the surfaces on each population could not be determined separately. The objectives of this study were (a) to examine cell behavior on implants in which connective tissue contacted surfaces of various topographies and epithelium encountered only a smooth surface, and (b) to compare one‐ stage and two‐stage surgical techniques. Implants had a base component (BC) which was either smooth or had a surface with 19‐pm‐ or 30‐pm‐deep grooves or 120‐pm‐ deep tapered pits, and a skin‐penetrating component (SPC) which was smooth. In the two‐stage technique, the BC was implanted subcutaneously for 8 weeks, which permitted the healing of the periimplant connective tissue. In the second stage the SPC was connected to the BC. For one‐stage implants, BC&SPC were connected and implanted percutaneously. Implants (BC&SPC) were removed 1, 2, or 3 weeks after percutaneous implantation and histological sections were measured for recession, connective tissue and epithelial attachment as well as capsule thickness. Light microscopy indicated that both grooved and tapered pitted surfaces encouraged connective tissue ingrowth. On the grooved surfaces, the orientation of fibroblasts changed from an oblique to a more complex pattern which included cells having round nuclei within the grooves, as well as cells oriented oblique or perpendicular to the grooves. In the tapered pits a hammock‐like arrangement of fibroblasts was observed. In some cases, foci of mineralization and formation of bonelike tissue were found on the grooved and pitted surfaces. The apical migration of the epithelium was significantly (p<0.05) inhibited by those micromachined surfaces which produced connective tissue ingrowth to the BC. This study found that placing the implants in two stages improved the performance of percutaneous devices, and that a further improvement was achieved if the implant had a surface promoti

ISSN:0021-9304    

DOI:10.1002/jbm.820260407

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractBiopsies secured during reentry surgical evaluation of previously treated periodontal osseous defects were examined for gingival tissue response to HTR polymer. Eleven patients provided biopsies of HTR grafted sites 6‐7 months after initial implantation. Minimal inflammation and infrequent foreign body giant cells were found. Bone was present in about half of the samples and osteogenesis associated with the HTR graft material was seen in about 20% of the biopsies. Serendipitously, biopsies of other graft materials or debridement only sites from 6‐30 months post‐treatment were also available for analysis and comparison, and showed similar tissue response. The results of this study suggest that HTR polymer (and other graft materials) is very biocompatible and elicits no untoward gingival tissue responses when placed in periodontal osseous de

ISSN:0021-9304    

DOI:10.1002/jbm.820260408

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe interface between mandibular bone and endosteal dental implants was examined with anin vivodog model. Undecalcified mandibular implant samples were observed with both conventional transmission electron microscopy and highvoltage transmission electron microscopy (HVEM). Results demonstrated the variable nature of the interfacial support tissues. Mineralized bone was often found within 50 nm of the implant surface, separated from that surface only by an electron dense deposit. Osteocytes were observed close to the interface encased within lacunae extending numerous cellular processes through canaliculi. An osteoblast was also observed directly at the interface within a developing lacuna. Other interfacial areas exhibited a finely fibrillar and more electron lucent morphology. Furthermore, other areas were shown to be composed of wider zones of extracellular products containing collagen fibrils, ground substance, and calcified inclusions. Because bone is a n actively growing and remodeling tissue, these different morphological zones around the entire area of the implants would appear to confirm the dynamic tissue response to endosteal dental implants. Further, HVEM stereology was shown to be an exciting research tool to investigate this tissue response.

ISSN:0021-9304    

DOI:10.1002/jbm.820260409

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820260410

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820260411

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY