ISSN:0021-9304    

DOI:10.1002/jbm.820270102

出版商:John Wiley&Sons, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractA new biomaterial has been developed by fixing native collagen with a polyepoxy compound (PC) fixative. In this study, bovine internal thoracic arteries were fixed with PC under various conditions to help understand the kinetics of the collagen–PC reactions and optimize the fixation process. At predetermined time intervals, small samples were cut from the arteries to determine the quantities of the remaining unreacted amino acids in the collagen. Temperature, concentration, and solution pH were among the key parameters studied. The overall fixation rate was found to be reaction‐rate controlled, as the rate of fixation was relatively slow compared with the rate of diffusion of PC. As might be expected, the reaction rate was favored by a higher temperature, concentration, and solution pH. A kinetic model, with a 2.5th reaction order with respect to the reactive functional groups of collagen and a first order with respect to PC, was developed that gave a good fit to the experimental data. Based on this model, the degree of fixation,X, as a function of time,t, is given by (1 –X)−1.5= 1 +Kt, whereKis a constant related to the intial concentrations and the reaction rate constant. © 1993 John Wiley&S

ISSN:0021-9304    

DOI:10.1002/jbm.820270103

出版商:John Wiley&Sons, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractCartilaginous implants for potential use in reconstructive or orthopedic surgery were created using chondrocytes grown on synthetic, biodegradable polymer scaffolds. Chondrocytes isolated from bovine or human articular or costal cartilage were cultured on fibrous polyglycolic acid (PGA) and porous poly(L)lactic acid (PLLA) and used in parallelin vitroandin vivostudies. Samples were taken at timed intervals for assessment of cell number and cartilage matrix (sulfated glycosaminoglycan [S‐GAG], collagen). The chondrocytes secreted cartilage matrix to fill the void spaces in the polymer scaffolds that were simultaneously biodegrading.In vitro, chondrocytes grown on PGA for 6 weeks reached a cell density of 5.2 × 107cells/g, which was 8.3‐fold higher than at day 1, and equalled the cellularity of normal bovine articular cartilage.In vitro, the cell growth rate was approximately twice as high on PGA as it was on PLLA; cells grown on PGA produced S‐GAG at a high steady rate, while cells grown on PLLA produced only minimal amounts of S‐GAG. These differences could be attributed to polymer geometry and biodegradation rate.In vivo, chondrocytes grown on both PGA and PLLA for 1–6 months maintained the three‐dimensional (3‐D) shapes of the original polymer scaffolds, appeared glistening white macroscopically, contained S‐GAG and type II collagen, and closely resembled cartilage histologically. These studies demonstrate the feasibility of culturing isolated chondrocytes on biodegradable polymer scaffolds to regenerate 3‐D neocartilage. © 1993 J

ISSN:0021-9304    

DOI:10.1002/jbm.820270104

出版商:John Wiley&Sons, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractSynthetic calcium phosphate ceramic (CPC) surfaces can be transformed to a biological apatite through a sequence of reactions which include dissolution, precipitation, and ion exchange. By virtue of the reactions being material‐dependent, it is important to determine parametric rate effects. In this study we focused on the effect of stoichiometry and crystal structure of CPCs on the dissolution kinetics. Monophse, biphase, and multiphase CPCs with a Ca/P ratio equal to or greater than 1.5 were studied. The experiments were performed in a calcium‐ and phosphate‐free Tris buffer solution at pH 7.3. The dissolution behavior of the CPCs studied was found to vary over a wide range. The dissolution rate of the monophase CPCs increased in the order of stoichiometric hydroxyapatite, calcium deficient hydroxyapatite, oxyhydroxyapatite, β‐tricalcium phosphate, α‐tricalcium phosphate, and tetracalcium phosphate. Dissolution of biphase and multiphase CPCs increased prorated the concentration of more soluble component. © 1993 John Wi

ISSN:0021-9304    

DOI:10.1002/jbm.820270105

出版商:John Wiley&Sons, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe formation of a biologically equivalent carbonatecontaining apatite on the surface of synthetic calcium phosphate ceramics (CPC) may be an important step leading to bonding with bone. Reactions of several single phases CPCs upon immersion into a simulated physiologic solution (SPS) with an electrolyte composition of human plasma were determined. The CPCs covered a wide range of solution stabilities from low‐soluble hydroxyapatites (HA) to metastable tricalcium phosphates (TCP) and tetracalcium phosphate (TTCP). Changes in chemical composition of SPS and infrared spectral features after CPC immersion were analyzed. New phase formation was observed on all the CPCs. However, kinetics, compositions, and structures of the new phases were significantly different. The studied CPCs can be characterized by the time to new phase formationin vitro; the minimum time for measurable precipitate formation was found to increase in the order: not‐well‐crystallized HAs

ISSN:0021-9304    

DOI:10.1002/jbm.820270106

出版商:John Wiley&Sons, Inc.    

年代:1993

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820270107

出版商:John Wiley&Sons, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractTo determine the meaning of graylevels in backscattered electron (BSE) images of actual bone tissues, the influence of mineral content and mineral composition on BSE image graylevels was studied using chick bone tissue representing a broad age range. These tissues were analyzed for BSE image graylevels, Ca/P molar ratios, mineral composition, mineral content (v/v), ash fraction (w/w), and density (g/cm3). Linear regression analyses showed that the weighted mean graylevels (WMGLs) in BSE images were positively correlated to ash fraction (r2= 0.711), mineral content (r2= 0.720), and density (r2= 0.843). Although the Ca/P ratio increased from 1.65 in embryos to 1.80 in 2‐year olds, the compositional changes corresponding to this Ca/P molar ratio were estimated to produce a relatively minor (<4.0%) change in BSE image graylevel. These results demonstrate that graylevels in BSE images of actual bone tissue can be attributed to mineral content and density, but only as a coincidence of their association with atomic number. © 1993 John Wiley&Sons, I

ISSN:0021-9304    

DOI:10.1002/jbm.820270108

出版商:John Wiley&Sons, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractBiomaterials elicit an inflammatory response that is undoubtedly a factor in their heading and in the complications associated with their use. Herein, we report the modification of a rat air pouch in which we measured the production of intracellular hydrogen peroxide by inflammatory cells adherent to the surfaces of silicone elastomer (SE) and expanded polytetrafluoroethylene (ePTFE). We used the fluorescent probe dichlorofluorescein diacetate (DCFH‐DA) to measure the intracellular production of hydrogen peroxide 2 and 7 days after implantation. After 2 days, host cells adherent to ePTFE produced almost 3.5 times more hydrogen peroxide than did cells adherent to SE (P<.001). By 7 days, the H2O2production on cells adherent to ePTFE had decreased while that on cells adherent to SE was unchanged. These data indicate that the air pouch is a good alternative to otherin vivomodels for studies of the biological reactions induced by biomaterials. © 1993 John Wiley&Sons, I

ISSN:0021-9304    

DOI:10.1002/jbm.820270109

出版商:John Wiley&Sons, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThis study is the first description of the extensive porosity which is preferentially located at the cement‐prosthesis interface of cemented femoral components of total hip replacements. The observation is important because the interfacial porosity may decrease the strength of the cement‐femoral prosthesis interface and jeopardize the mechanical integrity of the cement mantle. We examined the cement‐metal interfaces from a multiplicity ofin vivoandin vitrospecimens using both optical and scanning electron microscopy. These samples included several stem designs, implants made from either Co‐Cr or Ti alloy, implants made with a variety of surface finishes and both centrifuged and uncentrifuged cement. Allin vivoandin vitrosamples had marked porosity in the cement focally concentrated at the cement‐metal interface. The amount of porosity at the interface greatly exceeded the amount of general porosity found throughout the bulk cement. Centrifuging did not affect the interfacial porosity, and neither did alloy nor surface finish. The presence of these pores may be expoained by the rheological characteristics of the cement. © 1993 John Wiley

ISSN:0021-9304    

DOI:10.1002/jbm.820270110

出版商:John Wiley&Sons, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractA new type of biomaterial for artificial skin was developed as a form of sponge by combining fibrillar collagen (F‐collagen) with gelatin. The sponge was physically and metabolically stabilized by introducing dehydrothermal cross links. To get the final product, various conditions in the preparation of sponges were evaluated byin vitrocellular responses andin vivotissue reactions. Fibroblasts placed on a sponge of gelatin attached themselves to it, migrated well into the sponge, and remained inside it for at least 7 days. However, sponges of gelatin showed structural instability for hydrolytic degradation by the cells. Most fibroblasts appeared not to penetrate into the interior of a sponge of F‐collagen but to remain on its surface when fibroblasts were placed on the sponge, suggesting poor attraction of F‐collagen revealed an intense infiltration of neutrophils into the sponge, indicating F‐collagen as an inducer of the inflammatory reaction. These aggravating characters of F‐collagen sponges were greatly improved by blending gelatin with F‐collagen. The new type of collagen‐based biomaterials developed in the present study is expected to become a useful matrix substance for artificial skin. © 1993 John W

ISSN:0021-9304    

DOI:10.1002/jbm.820270111

出版商:John Wiley&Sons, Inc.    

年代:1993

数据来源: WILEY