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  • 1
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The aim of this study is the in vitro evaluation of the functional modifications of human endothelial cells in the presence of Dacron® impregnated with resorbable proteins. For this purpose, human endothelial cells isolated from the umbilical vein have been put in contact for 48 h with knitted Dacron® impregnated with collagen or gelatin and with nonimpregnated knitted Dacron® and double velour Dacron®. As control, endothelial cells cultured in the absence of material were used. After the contact time, cell counts were performed. In addition, the concentrations of two proteins synthesized by endothelium, tissue plasminogen activator (t-PA) and plasminogen activator inhibitor 1 (PAI-1), were evaluated on the supernatants. In the cultures in contact with Dacron® impregnated with collagen or gelatin and in those in contact with knitted Dacron®, we have observed a smaller cell growth than that observed in cultures without materials. The synthesis of t-PA showed some significant variations between the control cultures and those in contact with the materials. PAI-1 production was significantly reduced in the cultures in contact with gelatin impregnated Dacron® and with knitted Dacron®. Double velour Dacron® caused no significant variation in any of the examined parameters. © 1994 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 4 (1993), S. 249-252 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: An in vitro evaluation was conducted of the adhesion capabilities of rabbit corneal endothelial cells on intraocular lenses (IOLs) made of heparin-coated polymethylmethacrylate (HSM-PMMA). The concave endothelial surfaces of albino rabbit corneas were placed in contact in vitro with the convex surfaces of the optical side of HSM-PMMA IOLs in 4-day cultures. PMMA IOLs served as controls. After an incubation period, the preparations were examined via phase-contrast microscopy and via inverted microscopy after staining with vital dye (neutral red), both with and without the cornea in place. After fixation and staining with Giemsa, the cells adherent on the lens were counted on five different microscopic fields. It was observed that the corneal endothelial cells adhered equally to heparin-coated and untreated PMMA IOLs. © 1993 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 11 (1977), S. 657-669 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Laboratory tests carried out by means of body environment simulators have proved to be very important for the evaluation of endoprostheses potentially useful for implantation. The present paper examines the problems connected with the design of such a simulator. The results obtained with an initial, very primitive simulator concerning the outlines of the phenomena of wear, corrosion, and friction and some wear properties of commercially available hip endoprostheses are presented. From these results, the motivation that led to the design of a more advanced simulator is presented. This latter simulator is also described.
    Additional Material: 5 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 31 (1996), S. 183-191 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In this study the toxic effects of chromium, nickel, and cobalt extracts on in vitro cultured lymphocytes were evaluated. Graphite furnace atomic absorption spectrometry was used to measure the ion concentration. After serial dilution of the extracts, the viability of lymphocytes at 24, 48, and 72 h was estimated by flow cytometry, including propidium iodide staining and light scatter property assessment, and by MTT reduction test. The results of the investigation allowed us to conclude that 1) standardization of the procedure for preparing extracts is fundamental to obtaining repeatability of results; 2) the toxicity of an extract cannot be evaluated with a single viability assay; a combination of functional and structural tests is required; 3) when methods based on enzymatic reactions are performed, e.g. MTT test, it is advisable to replace the extract containing metal ions with fresh medium in order to avoid any interference with viability testing; 4) the amount of Co and Ni in the extract is similar, but the Cr release is very poor; 5) the lower toxicity of Cr extract probably is due to the lower ion concentration; 6) the assessment of 50% cytotoxic concentration, (TC50) allows quantification of materials toxicity and comparison of various metals; and 7) the determination of a noncytotoxic concentration, i.e., a concentration lower than TC10, is required for subsequent investigation of cell functions because such studies can be carried out only on viable cell population. © 1996 John Wiley & Sons, Inc.
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  • 5
    ISSN: 0021-9304
    Keywords: leukocytes ; adhesion molecules ; flow cytometry ; polyethylene terephthalate ; pyrolytic carbon ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Leukocyte activation is one test for the evaluation of blood-materials interaction. The expression of adhesion molecules analyzed by flow cytometry provides a simple method to evaluate leukocyte activation by biomaterials: any change in these molecules can be predictive of the inflammatory activity of the materials. In this study the contact between leukocytes and uncoated polyethylene terephthalate or pyrolytic carbon-coated polyethylene terephthalate (PET and PET-PC, respectively) was inspected by analyzing whether the expression of some adhesion molecules involved in leukocyte activation, namely LFA-1 (CD11a/CD18), Mac 1/CR3 (CD11b/CD18), and LECAM-1 (CD62L) can be modified. By flow cytometry expression of the adhesion molecules can be studied separately on lymphocytes and myeloid cells. The materials tested reduced the total numbers of both leukocytes and neutrophils, although not significantly. Neither PET nor PET-PC changed the expression of the adhesion molecules in lymphocytes: this suggests that no specific immune response is stimulated. On the contrary, statistically significant changes were observed for monocytes and granulocytes: the percentage of cells expressing Mac-1 and the density of such antigens on cell membranes increased while the percentage of LECAM-1 positive cells decreased. Similar changes were observed when the cells underwent the inflammatory stimulus provided by an in vitro challenge with bacterial endotoxin. Our results demonstrated that polyethylene terephthalate activates leukocytes by modifying the expression in neutrophils of the molecules involved in the early phase of the inflammatory response. Even after coating PET with pyrolytic carbon, the ability of this material to activate circulating leukocytes was maintained. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 39, 549-553, 1998.
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  • 6
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The aim of this study was the evaluation of the in vitro production of prostacyclin, and of tissue plasminogen activator (tPA) and its inhibitor, PAI-1, by human endothelial cells cultured in the presence of polyethylene terephthalate (PET). After a 48 h contact between the cells and the polymer, the concentration of 6-keto-PGF1α, a stable metabolite of prostacyclin, tPA, and PAI-1, was assayed on the supernatants. Contact of the endothelial cells with PET produced a highly significant reduction of 6-keto-PGF1α with respect to control cultures. Tissue plasminogen activator concentration in the supernatants of the cultures in contact with the material was similar to that observed in the controls, while PAI-1 production was significantly reduced. It can be concluded that the contact between endothelial cells and PET determines a reduction in the platelet aggregability and an increase of the fibrinolytic activity due to a decrease in PAI-1, while tPA concentration remains unchanged. © 1993 John Wiley & Sons, Inc.
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  • 7
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: We evaluated the role of the immune system in the pathogenesis of the periprosthetic capsular contracture, the most frequently occurring complication following the implant of silicone prostheses. Peripheral blood samples from 22 patients with silicone-gel-filled implants were examined. In all cases a capsule was felt by palpation, and it was classified according to the Baker scale. Ten patients (group 1) had a Baker 2 contracture, and 12 (group 2) had severe contracture rated 3 and 4. The cells positive to antigens CD3, CD4, CD8, HLA-DR, CD19, CD25, CD57, CD16, and CD14, and the cytotoxic activity of the lymphocytes on target cells K562 were assessed by cytofluorimetric analysis. At time 0 there were no statistically significant differences between patients and normal subjects, nor between the two groups. At 48 h, the group 2 patients had a number/mm3 of cells CD57 + significantly higher than both group 1 and control group (P 〈 .05). In group 1 patients, the cytotoxic activity was similar to that of normal subjects, whereas in group 2 it was significantly increased, in respect to both the controls (P 〈 .05) and group 1 (P 〈 .001). In all groups, the contact of the lymphocytes with the silicone extract did not modify either the antigen expression or the lymphocyte functional activity. On the basis of these results we hypothesize the involvement of the immune system in the formation of the capsular contracture around the prosthesis. © 1995 John Wiley & Sons, Inc.
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  • 8
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The functional response of peripheral blood lymphocytes isolated from 22 patients with silicone gel-filled breast implants was assessed after in vitro re-exposure to silicone. Using cell culture test methods to quantify proliferation and viability and/or activation of lymphocyte microcultures, i.e., the uptake of tritiated thymidine (3H-TdR uptake test) and the reduction of formazan salts (MTT assay), interesting data were obtained. Peripheral blood lymphocytes purified from patients wearing silicone gel-filled breast implants react in vitro to silicone showing a statistically significant increase of both proliferation and viability, while healthy subjects do not respond on in vitro exposure to silicone. Differences resulted even more statistically significant when patients were divided into two groups depending on the type of surgery they underwent: patients with breast augmentation for aesthetic reasons seem to have an increased responsiveness in vitro to silicone compared to patients who experienced a reconstructive surgery of the breast. Although they are still preliminary, being referred to a limited population, these results suggest that the lymphocytes of patients with silicone gel-filled breast implants could be sensitized in vivo toward silicone; the re-exposure of these cells to silicone leads to a higher functional response which could be looked for by using quantitative in vitro test methods. © 1995 John Wiley & Sons, Inc.
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  • 9
    ISSN: 0021-9304
    Keywords: metals ; granulocytes (PMNs) ; reactive oxygen species ; 2′,7′-dichlorofluorescin-diacetate ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This report describes a simple, rapid, automated microassay for measuring in vitro changes of oxidative burst of phagocytes following challenge with metals for orthopedic devices. The production of reactive oxygen species (ROS) by polymorphonuclear leukocytes (PMNs) was measured using 2′,7′-dichlorofluorescin-diacetate (DCFH-DA) as fluorescent probe. DCFH-DA enters the cells and is oxidized by ROS to fluorescent DCF. The DCF generated was directly proportional to ROS produced intracellularly: The fluorescence intensity was read and converted to an index of ROS production by cells. In our experimental system, granulocytes (PMNs) were isolated from normal human blood and seeded in microplates. To verify if metals could influence ROS production, chromium, cobalt, nickel, molybdenum, titanium, aluminum, and vanadium prepared as aqueous extracts in phosphate-buffered saline were tested onto PMNs using phorbolmyristate acetate (PMA) as positive control. Molybdenum, aluminum, and vanadium increased ROS generation by PMNs, while signals not different from unstimulated PMNs were recorded for chromium, cobalt, nickel, and titanium. The DCFH-DA microplate-based assay provides an in vitro tool for the detection of oxygen-reactive species generated by PMNs as a response to metals. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 41, 455-460, 1998.
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  • 10
    Publication Date: 1995-01-01
    Print ISSN: 0142-9612
    Electronic ISSN: 1878-5905
    Topics: Biology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Medicine
    Published by Elsevier
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