摘要:

AbstractAnew synthetic amino acid copolymer has been evaluated as wound covering. It is permeable to water vapor in the region of 4.1 kg/m2/24 h, it does not allow microbial proliferation afterin vitroinoculation, it is impermeable to bacteria, and is stable and flexible.In vivoexperiments were designed to provide qualitative and quantitative evaluation on its possible use as a skin substitute in full‐thickness skin excision in the guinea pig. Two excisions, approximately 12–;14 cm2were performed on each side of the spine, leaving the panniculus carnosus. One site was treated with the membrane, the other with gauze. Each animal served as its own control. Photographs with a fixed focal‐length camera were taken in identical conditions for all wounds immediately and 7,14, and 21 days after excision. They were analyzed by planimetry. Histological studies were performed at 7,14, and 21 days. The rate of healing between 0 and 21 days of the wounds treated with the copolymer membrane was significantly accelerated in comparison with wounds covered with a dry dressing (p<0.05). This increased epithelialization rate was confirmed by histology, which also suggested a reduction of the inflammatory response of the wound.In vivobiodegradation studies were also performed by subcutaneous implantation in the rat followed at 15, 30, 60, and 90 days by histology and physicochemical analyses. The results demonstrate that the membrane is not biodegra

ISSN:0021-9304    

DOI:10.1002/jbm.820260602

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe ultimate objective of this work is to develop a device that can be triggered by morphine to release naltrexone. In this device, naltrexone is dispersed in cellulose acetate phthalate microspheres which are then spray‐coated with a trilaurin protective coating. The microspheres are contained within a macroporous cylinder which also contains a reversibly inactivated lipase. This enzyme in its inactive state is unable to remove the protective coating but in its active state is able to do so. Inactivation is achieved by the covalent attachment of morphine followed by complexation with a morphine antibody. Triggering is accomplished by the displacement of the lipase‐morphine conjugate from the antibody. In this phase we have investigated the effect of lipase on the release of naltrexone from trilaurincoated microspheres and found that the coated microspheres are stable in a pH 7.4 phosphate buffer at 37°C for at least 1 month, but release 80% of the incorporated naltrexone in one hour when 100 nig of capsules in 5 mL buffer are exposed to 25 μg of l

ISSN:0021-9304    

DOI:10.1002/jbm.820260603

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractA parallel‐plate flow chamber is developed in order to study cellular adhesion phenomena. An image analysis system is used to observe individual cells exposed to flow in situ and to determine area, perimeter, and shape of these cells as a function of time and shear stress. With this flow system the behavior of human fibroblasts spread on glass is studied when exposed to an increasing laminar flow. The flow system appears to be well‐suited for following individual cells during detachment. After 75 to 90 min, at a shear stress of 350 dynes/cm2, more than 50% of the spread cells are detached from the surface. Cells with higher spreading areas stay longer at the glass surface. Cells round up before detaching. Sometimes the cell body is attached to the substratum through a thin filament during detachment. At the scanning electron microscopy level numerous filopodial extensions are observed. Cell material could only rarely be observed at the light or scanning electron microscopic level on the substratum once a cell was detac

ISSN:0021-9304    

DOI:10.1002/jbm.820260604

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractBiological responses to heparinized segmented polyurethaneurea (SPUU‐PEO‐Heparin) were evaluated in uitro andex vivo. In uitro assays involved plasma protein adsorption, platelet adhesion, and release reaction studies. In addition, anex vivorabbit arterio‐artery (A‐A) shunt experiment was also performed to measure occlusion times of the heparinized surfaces. All SPUU‐PEO‐Heparin surfaces demonstrated less protein adsorption than Biomer® and protein adsorption patterns similar to SPUU‐PEO surfaces. Platelet adhesion and release studies demonstrated that both SPUU‐PEO‐Heparin and SPUU‐PEO surfaces adsorbed less platelets and inhibited platelet release, as compared to Biomerm. These findings correlated with reduction in protein adsorption observed for the modified surfaces. In low flow rate ex‐vivo A‐A shunt experiments, all heparinized surfaces prolonged occlusion time longer than controls. However, SPUU‐PEO surfaces did not prolong occlusion time whencompared to BiomerB, although these surfaces suppressed protein adsorption and platelet interaction in vitru. The improved blood compatibility of SPUU‐PEO‐Heparin surfaces attest to the usefulness of this approach in improving the blood compatibilit

ISSN:0021-9304    

DOI:10.1002/jbm.820260605

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractResidence time‐dependent changes in fibrinogen after adsorption to six different polyurethanes were examined by measuring polyclonal antifibrinogen binding to the adsorbed protein. The amount of adsorbed fibrinogen that could be eluted by sodium dodecyl sulfate (SDS) was also measured. Baboon fibrinogen was first adsorbed from dilute plasma to the polymers, which were then stored in either buffer or buffered albumin solution prior to testing. Subsequently, the amount of antifibrinogen bound by the adsorbed fibrinogen was measured using a direct enzyme linked immunosorbent assay (ELISA). Alternatively, the surface with the adsorbed fibrinogen was soaked in a 3% SDS solution, and the amount of retained125I‐radiolabeled fibrinogen was measured. With increasing residence time, decreases in both antibody binding and the SDS elutability of the adsorbed fibrinogen occurred, but the rate of change was dependent on the polyurethane to which the fibrinogen was adsorbed. In addition, the antibody binding per unit of adsorbed fibrinogen, when measured immediately after the adsorption step, varied by approximately a factor of 3 among the various polyurethanes. When the protein‐coated surfaces were stored in buffered albumin solution rather than buffer, the decrease in the reactivity of fibrinogen with residence time did not occur on some of the surfaces. This study shows that the chemical properties of the adsorbing surface influence the rate at which adsorbed fibrinogen undergoes change. The significance of the polymer‐dependent changes in adsorbed fibrinogen with respect to blood reactions with polymers is di

ISSN:0021-9304    

DOI:10.1002/jbm.820260606

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractReduction of protein adsorption by coating surfaces with polyethylene glycol (PEG) is well documented. The present work has four goals related to these previous studies: first, to develop chemistry providing densely packed, covalently bound PEG on polystyrene (PS); second, to determine the ability of these modified surfaces to reject fibrinogen; third, to compare the protein‐rejecting ability of branched and linear PEGs; and fourth, to examine the utility of an ELISA‐type procedure for measuring protein adsorption. It was found that PEG‐epoxide could be readily coupled to amine groups of poly(ethy1ene imine) (PEI), which had been preadsorbed onto an oxidized PS surface. The PEG groups on branched PEGs appear to act as an excluded volume to repel proteins, similar to arguments previously raised for linear PEGs. The results of protein adsorption studies showed that fibrinogen adsorption is significantly reduced by coating polystyrene with either linear or branched PEGs of 1500 to 20,000 in molecular weight. The ELISA technique was found to be equivalent in sensitivity to radiolabeled fibrinogen for estimating adsorption levels. It is expected that PEG‐coated PS will have much utility in a variety of biomedical appli

ISSN:0021-9304    

DOI:10.1002/jbm.820260607

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractLocal hemostatics for osseous tissue should preferably be absorbable and biocompatible and should not inhibit osteogenesis. The tissue response and effect on demineralized boneinduced heterotopic osteogenesis in the abdominal muscle of 120 male Wistar rats by different local hemostatics were evaluated by light microscopy and85Sr uptake analyses. Nonabsorbable bone wax of 88% beeswax and absorbable bovine fibrin–collagen paste both significantly inhibited o st eoinduction, whereas a bioerodible polyorthoester drug delivery system with or without 4% gentamicin did not. Bone wax was not absorbed and induced a chronic foreign body reaction. Fibrin–collagen paste induced less inflammation with numerous monocytes and macrophages with engulfed material. Bioerodible polyorthoester caused a very moderate tissue reaction and was mostly resorbed at wee

ISSN:0021-9304    

DOI:10.1002/jbm.820260608

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractA series of segmented polyurethanes (SPUs) with various polyol soft segments was prepared and their hydrolytic degradation and degradation due to lipid sorption was investigated. The hydrolytic degradation of the SPUs was investigated in a papain solution, where it was shown that the SPU based on poly(ethy1eneoxide) (PEO) soft segment was susceptible to hydrolytic degradation. X‐ray photoelectron spectroscopic (XPS) data suggest dissociation of the urethane linkage by enzymatic degradation. Degradation by lipid sorption was observed for the SPU based on a poly(dimethylsi1oxane) (PDMS) soft segment. This is ascribed to the high solubility of lipid in the PDMS segment of the SP

ISSN:0021-9304    

DOI:10.1002/jbm.820260609

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe interaction between corrosion products of metallic implants and the surrounding tissue is important in determining the biocompatibility of the implant, in particular the interaction of corrosion products with inflammatory cclls such as neutrophils and macrophages. Such cells are capable of releasing enzymes and high‐energy oxygen radicals which can damage the tissue. Clearly, any factors that influence cell movement to the implant site could influence the biocompatibility of the implant. The present study examined the influence that copper and nickel ions had on neutrophil locomotion. Both copper and nickel ions stimulated a proportion of the neutrophil population to take up a nonspherical morphology and to locomote. These metal ion stimulated cells have higher circularity values and move slower than neutrophils incubated with FM1.P. For both FMLP and nickel ion stimulated cells, there is a correlation between the speed of neutrophil locomotion and neutrophil circularity; as the neutrophil circularity value decreases, the speed of locomotion increase

ISSN:0021-9304    

DOI:10.1002/jbm.820260610

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820260611

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY