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  • 1
    Electronic Resource
    Electronic Resource
    Bioresorbable Phosphate Scaffolds for Bone Regeneration (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 361-363 (Nov. 2007), p. 241-244 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this work, a new bioresorbable phosphate glass (I-CEL2) was prepared in order to useit for the production of 3D-bioresorbable scaffold for bone regeneration. I-CEL2 was characterizedto assess its thermal characteristics as well as its bioresorption rate in different medium such asdistilled water, Tris-HCl and Simulated Body Fluid (SBF). 3D-macroporous scaffolds wereprepared by mixing and pressing I-CEL2 powders and an organic phase and by treating the compactof powders at 550°C for 3 hours. The obtained scaffolds showed a very high porosity and a highresorption rate and are thus suitable candidates for a scaffold to be used as a temporary guide forbone regeneration. The initial response of human marrow stromal cells (hMSCs) has been tested onI-CEL2 surface to describe its biological potential
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/56/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.361-363.241.pdf
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  • 2
    Electronic Resource
    Electronic Resource
    Behaviour of endothelial cells cultured in the presence of polymers impregnated with adsorbable proteins (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 47-50 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770050107
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  • 3
    Electronic Resource
    Electronic Resource
    Assessment of metal extract toxicity on human lymphocytes cultured in vitro (1996)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 31 (1996), S. 183-191 
    Details
    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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  • 4
    Electronic Resource
    Electronic Resource
    Flow-cytometric analysis of leukocyte activation induced by polyethylene-terephthalate with and without pyrolytic carbon coating (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 39 (1998), S. 549-553 
    Details
    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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  • 5
    Electronic Resource
    Electronic Resource
    Production of prostacyclin and fibrinolysis modulators by endothelial cells cultured in the presence of polyethylene terephthalate (1993)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 27 (1993), S. 1161-1164 
    Details
    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.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820270906
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  • 6
    Electronic Resource
    Electronic Resource
    Silicone breast implants: The role of immune system on capsular contracture formation (1995)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 29 (1995), S. 197-202 
    Details
    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.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820290209
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  • 7
    Electronic Resource
    Electronic Resource
    Assessment of viability and proliferation of in vivo silicone-primed lymphocytes after in vitro re-exposure to silicone (1995)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 29 (1995), S. 583-590 
    Details
    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.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820290505
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  • 8
    Electronic Resource
    Electronic Resource
    Fluorescent microplate assay for respiratory burst of PMNs challenged in vitro with orthopedic metals (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 41 (1998), S. 455-460 
    Details
    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.
    Additional Material: 4 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Cytotoxicity testing of materials with limited in vivo exposure is affected by the duration of cell-material contact (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 42 (1998), S. 485-490 
    Details
    ISSN: 0021-9304
    Keywords: cytotoxicity ; impression materials ; addition-type-silicones ; condensation-type-silicones ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Silicones for dental impression largely are used to record the geometry of hard and soft dental tissues. They are considered to be medical devices, and the assessment of cytotoxicity is a necessary step in the evaluation of their biocompatibility. Extracts of six addition-type and six condensation-type silicones have been tested with L929 cells according to the ISO 10993 - Part 5 standard. The cytotoxicity was evaluated by three different methods: neutral red uptake, propidium iodide (PI) staining, and amido black staining. According to the selected specific assay, contact between cells and material extracts was maintained for 24 h in the first series of experiments; then, considering that in vivo application of these materials is restricted to a few minutes, additional experiments were performed after 1 h of cell/extract contact. Analysis of the results showed that the addition-type silicones are nontoxic even when tested after prolonged exposure of the cells to the materials while the condensation-type silicones were cytotoxic at 24 h of incubation. Nevertheless, harm to the patient actually could be negligible, considering its very short time of exposure in vivo. This is supported by our finding that most are not toxic after 1 h. We suggest that the experimental conditions of cytotoxicity testing have to be relevant to the in vivo situation; accordingly, the time of exposure should be designed carefully. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 42, 485-490, 1998.
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  • 10
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    Collagen Hybrid Formulations for the 3D Printing of Nanostructured Bone Scaffolds: An Optimized Genipin-Crosslinking Strategy (2020)
    Molecular Diversity Preservation International
    Details
    Publication Date: 2020-08-27
    Description: Bone-tissue regeneration induced by biomimetic bioactive materials is the most promising approach alternative to the clinical ones used to treat bone loss caused by trauma or diseases such as osteoporosis. The goal is to design nanostructured bioactive constructs able to reproduce the physiological environment: By mimicking the natural features of bone tissue, the cell behavior during the regeneration process may be addressed. At present, 3D-printing technologies are the only techniques able to design complex structures avoiding constraints of final shape and porosity. However, this type of biofabrication requires complex optimization of biomaterial formulations in terms of specific rheological and mechanical properties while preserving high biocompatibility. In this work, we combined nano-sized mesoporous bioactive glasses enriched with strontium ions with type I collagen, to formulate a bioactive ink for 3D-printing technologies. Moreover, to avoid the premature release of strontium ions within the crosslinking medium and to significantly increase the material mechanical and thermal stability, we applied an optimized chemical treatment using ethanol-dissolved genipin solutions. The high biocompatibility of the hybrid system was confirmed by using MG-63 and Saos-2 osteoblast-like cell lines, further highlighting the great potential of the innovative nanocomposite for the design of bone-like scaffolds.
    Electronic ISSN: 2079-4991
    Topics: Physics
    Published by Molecular Diversity Preservation International
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