摘要:

AbstractA variety of biodegradable microspheres were prepared from L‐lactic acid, DL‐lactic acid, or glycolic acid homopolymers and copolymers of different molecular weights and monomer compositions. Phagocytosis of the microspheres by mouse peritoneal macrophages was studied in cell culture system using scanning electron microscopy as well as light microscopy. The diameter of microspheres prepared was less than 2 μm, regardless of the starting polymers. No dependence of the chemical nature of starting polymers was observed on the extent of phagocytosis of the microspheres by macrophages. Precoating the microspheres with water‐soluble macromolecules such as proteins had great influence on phagocytosis by macrophages. It was demonstrated that precoating with bovine serum albumin and non‐proteinaceous macromolecules reduced the phagocytosis of microspheres, while bovine γ‐globulin, human fibronectin, bovine tuftsin, and gelatin precoating enhanced the phagocytosis. This trend was not influenced by the presence of serum. Only in the case of gelatin precoating, the phagocytosis was greatly enhanced by the presence of serum as compared to precoating with other proteins. Microscopic observation clearly indicated that the phagocytosed microspheres were gradually degraded in the macrophage interior with the incubation time, leading to release of a fluorescent dye encapsulated in the microspheres. The rate of microsphere degradation in cells could be controlled by changing the molecular weight and the monomer composition of the copolymers comprising the m

ISSN:0021-9304    

DOI:10.1002/jbm.820221002

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractPolyethylene tubings, 2‐mm inner diameter and the length of 1 m, untreated or furnished with a covalently bonded heparin surface layer, were inserted as arterio‐venous shunts bilaterally in dogs. By compressing the middle part, the initial blood flow was adjusted to 10 or 40 mL/min. The thrombogenecity of the tubings was assessed by the patency of the shunts and by assaying the generation of fibrinopeptide A (FPA) in arterial blood and in blood after its passage through the shunts. In untreated shunts clotting rapidly occurred preceded by high FPA generation in blood passing through the shunts. The blood flow in heparinized shunts remained unchanged throughout the test period. At the low flow rate a certain degree of FPA generation in the shunts occurred. At the high flow rate no changes in FPA levels occurred. The function of the heparin surface is thus flow rate dependent. Systemtic heparinization and subsequent neutralization with protamine or administration of protamine alone did not interfere with the function of the heparin surf

ISSN:0021-9304    

DOI:10.1002/jbm.820221003

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to evaluate the usefulness of a mixture of apatitewollastonite containing glass ceramic (A–W · GC, 42–60 mesh in granule size) with fibrin as a bone defect filler. A bone defect was drilled in the proximal metaphysis of the rat tibia and was filled with (1) fibrin glue, (2) A–W · GC granules, or (3) A–W · GC–fibrin mixture. Nothing was placed in the defect of the controls. The animals were serially sacrificed until 8 weeks after the operation, and the defect site was histologically examined and histomorphometrically analyzed for quantitative evaluation of newly formed bone and blood vessels. The use of fibrin glue as the binder markedly increased the ease of handling the A–W · GC granules. In the controls, little trabecular regeneration was observed in the defect site. Early vascularization (confirmed by microangiography) increased and the repairing process was accelerated in the defects filled with fibrin. In these defects filled with A–W · GC granules, good bone formation was observed around the granules. Bone formation was accelerated in the defects filled with A–W · GC fibrin mixture. Thus, the mixture showed good osteoconductive potential as well as acceleration of the repair process. Therefore, A–W · GC–fibrin mixture is considered to be a

ISSN:0021-9304    

DOI:10.1002/jbm.820221004

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractA knee simulator was used to study the wear of carbon fiber reinforced UHMWPE(Poly Two) (Poly Two is a registered trademark of Zimmer, USA) tibial and patellar components against Ti‐6Al‐4V, titanium nitride (TiN)‐coated Ti‐6Al‐4V, and cobaltchromium‐molybdenum femoral components. The prostheses tested were regular sized Miller‐Galante total knees mounted on 316L stainless steel fixtures using bone cement. An environmental chamber surrounded the knee and maintained bovine serum lubricant at 37°C. The specimens were tested using consecutive blocks of 464 level walking steps, 8 ascending stairs and 8 descending stairs for a total of 100,000 steps. The wear mechanisms found on the tibial components were scratching, carbon fiber associated damage, surface deformation, pitting, minor abrasion, and delamination. Three forms of carbon fiber associated damage were identified; fibers pulled from the surface, broken fibers, and UHMWPE removed from the surface fibers. The SEM evaluation revealed a pit forming mechanism. No correlation was found between femoral component material and tibial surface damage. Visual examination of the femoral components revealed no signs of wear or scratching on the cobalt‐chromium‐molybdenum or TiN‐coated Ti‐6Al‐4V components. There were, however, many light surface scratches on the uncoated Ti‐6Al‐4V components, which were also observed in a supplementary test of an uncoated Ti‐6Al‐4V component tested with a convention

ISSN:0021-9304    

DOI:10.1002/jbm.820221005

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractFerrous based, corrosion resistant amorphous alloys supported the adhesion and growth of cultured chick neuronal cells, human marrow stromal cells (presumptive osteoblasts), bovine aortal endothelial cells, and hamster kidney fibroblasts. Alloys of compositions Fe60Ni10Cr10P13C7, Fe70Cr10P13C7, and Fe70Cr10P13B7were found to be suitable. In contrast the crystalline form of these alloys was markedly less effective. Outgrowth of neurites from neuronal cells was promoted by precoating the metal surface with either laminin or neurite promotion factor. The adhesion of osteoblasts and fibroblasts suggests that corrosion resistant metal glasses should be considered as biomaterials useful for orthopedic applications. The adhesion of neuronal cells accompanied by neurite outgrowth indicates that the system might provide a functional interface between the neuromuscular system and an electromagnetic material that could be useful in bionic engineering.

ISSN:0021-9304    

DOI:10.1002/jbm.820221006

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractSilicone rubber has great advantages as a contact lens material because of its very high oxygen permeability, softness, and excellent mechanical strength and durability. Practical application is hampered by inherent characteristics of elastomers, i.e., high tackiness and highly hydrophobic surface properties. By applying a thin layer, e.g., 5 nm, of plasma polymer of methane, it was found that all these disadvantages can be eliminated without sacrificing high oxygen permeation rate, e.g., less than 15% reduction. Optimization of operational parameters to achieve this task has been investigated. It was also found that under optimum conditions the coating withstood severe and repeated flexing of the contact lens.

ISSN:0021-9304    

DOI:10.1002/jbm.820221007

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractCollagen and glycosaminoglycan (GAG) dermal skin substitutes (membranes) were studied as substrates for cultured human epidermal keratinocytes. Structure of dermal substitutes was optimized for pore size to promote ingrowth of fibrovascular tissue from the wound bed and for culture of human keratinocytes of the membrane's surface. Pore size of the freeze‐dried material was regulated by control of the temperature of freezing between −50°C and −20°C and by concentration of starting materials between 0.17% and 1.62% wt/vol. A nonporous surface of collagen‐GAG was laminated to the membranes to provide a planar substrate for cultured epidermal kerationocytes. Thickness of dermal substitutes was regulated by control of the volume and concentration of starting materials. Biotin was conjugated to solubilized collagen for binding with avidin of specific quantities of biologically active molecules. The optimized membranes are suitable substrates for the culture of human epidermal keratinocytes, and together with the cells yield a composite material that is histologically simila

ISSN:0021-9304    

DOI:10.1002/jbm.820221008

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820221009

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820221001

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY