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  • 1
    Electronic Resource
    Electronic Resource
    161
Systemic Effect of Vacuum Assisted Closure®(V.A.C.®) Therapy in Porcine Full Thickness Acute Wounds (2005)
    Oxford, UK; Malden, USA : Blackwell Publishing Ltd/Inc.
    Wound repair and regeneration 13 (2005), S. 0 
    Details
    ISSN: 1524-475X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Vacuum Assisted Closure®(or V.A.C.®)* Therapy is the negative pressure wound therapy provided by the V.A.C.® System, available from KCI USA, Inc. This study was conducted in young Yorkshire swine to evaluate the effect of V.A.C.® locally and systemically on wound healing and cytokine levels in wound fluid and tissue and in serum. Two full thickness, excisional wounds were created on the dorsum of swine. In Group 1 (n = 6), one wound received V.A.C.® Therapy using a polyurethane foam V.A.C.® dressing and 125 mm Hg continuous negative pressure, and the second wound received DuoDERM®** without negative pressure. Group 2 animals (n = 4) served as controls and received only DuoDERM® on both wounds. Blood, wound fluid, and biopsy samples were taken at predetermined intervals and the levels of 10 cytokines and growth factors, the acute-phase inflammatory biomarker C-reactive protein (CRP), and immunoglobulins M & G were tested by ELISA. Preliminary data from the first phase of the study (n = 2 swine/group) indicated a trend toward lower serum CRP values and higher serum IgM and IgG levels in swine treated with V.A.C.® Therapy compared to controls. The remaining swine are being evaluated to determine whether V.A.C.® Therapy moderates the local inflammatory wound healing response. In addition, testing of splenic lymphocyte and peripheral blood lymphocyte, neutrophil, and monocyte functions are being performed to study possible systemic effects on the immune system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1067-1927.2005.130216bm.x
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  • 2
    Electronic Resource
    Electronic Resource
    Underlying mechanisms at the bone-surface interface during regeneration (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 32 (1997), S. 0 
    Details
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The goal of regenerative therapy around teeth and implants is to create a suitable environment in which the natural biological potential for functional regeneration of periodontal ligament and/or bone can be maximized. In order for the regenerative process to be successful, the following factors must be addressed: prevention of acute inflammation from bacteria, mechanical stability of the wound, creation and maintenance of blood clot-filled space, isolation of the regenerative space from undesirable competing tissue types, and the creation of a desirable surface chemistry, energy, roughness and microtopography that can directly influence cellular response, ultimately affecting the rate and quality of new tissue formation and, therefore, the regeneration process. This paper will review how surface characteristics (chemistry and roughness) can affect cell response and local factor production. To evaluate the effect of surface chemistry on cell proliferation and differentiation costochondral chondrocytes were grown on standard tissue culture plastic dishes sputter-coated with different materials. The results indicate that surface materials can elicit differential responses in cell metabolism and phenotypic expression in vitro. In a second study, the effect of varying titanium surface roughnesses on osteoblast-like cell behavior was examined. Surface roughness was found to alter osteoblast proliferation, differentiation and matrix production in vitro. In addition, production of PGE2 and TGFβ by these cells was also shown to increase with increasing surface roughness, indicating that substrate surface roughness also affects cytokine and growth factor production. The role of surface roughness in determining cellular response was further explored by comparing the response of osteoblasts grown on new and previously used surfaces. The results of these latter studies showed that cell proliferation, expression of differentiation markers and overall matrix production are not altered when cells are grown on used vs. virgin surfaces. This suggests the possibility that implants may be re-used, especially in the same patient, if they are appropriately treated. In this context, it should also be noted that rougher titanium surfaces may require more extensive cleaning procedures. From a global perspective, these studies provide some insight into how bone regeneration can be optimized in the presence of an implant or tooth root residing at the site of a bony defect. Since the new bone being produced, during regeneration, grows from a distal area toward the implant or tooth root surface, it is hypothesized that the osteoblasts growing on the surface of the implant may produce local factors that can affect the bone healing process distally. In short, it appears that the surface characteristics of an implant, particularly roughness, may direct tissue healing and, therefore, subsequent implant success in sites of regeneration by modulating osteoblast phenotypic expression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0765.1997.tb01399.x
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  • 3
    Electronic Resource
    Electronic Resource
    Alteration of hydroxylapatite coatings exposed to chemicals used in histological fixation (1994)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 28 (1994), S. 281-287 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Histological evaluation of retrieved devices allows for assessment of the biological response to the implants. Interaction between the biomaterial and the fluids used in the processing may alter the appearance or composition of the device. This may result in artifacts due to processing which are misinterpreted as being caused by the biological response. Alteration by the fluids used in fixation may be particularly important with materials that have a propensity to interact with aqueous environments, as in the case of calcium phosphate ceramics. Therefore, we examined the effects of various standard histological fixation techniques on hydroxylapatite coated metal implants. Of the techniques examined, fixation with ethanol appeared to affect the surface morphology the least, whereas fixation in unbuffered formalin appeared to affect the bulk composition of these samples the least. Fixation in buffered formalin resulted in marked changes in both surface morphology and bulk composition. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820280302
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  • 4
    Electronic Resource
    Electronic Resource
    Titanium surface roughness alters responsiveness of MG63 osteoblast-like cells to 1α,25-(OH)2D3 (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 39 (1998), S. 77-85 
    Details
    ISSN: 0021-9304
    Keywords: implant ; titanium ; osteoblasts ; surface roughness ; 1α,25- (OH)2D3 ; differentiation ; local factor ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Surface roughness has been shown to affect differentiation and local factor production of MG63 osteoblast-like cells. This study examined whether surface roughness alters cellular response to circulating hormones such as 1α,25-(OH)2D3. Unalloyed titanium (Ti) disks were pretreated with HF/HNO3 (PT) and then were machined and acid-etched (MA). Ti disks also were sandblasted (SB), sandblasted and acid etched (CA), or plasma sprayed with Ti particles (PS). The surfaces, from smoothest to roughest, were: PT, MA, CA, SB, and PS. MG63 cells were cultured to confluence on standard tissue culture polystyrene (plastic) or the Ti surfaces and then treated for 24 h with either 10-8M or 10-7M 1α,25-(OH)2D3 or vehicle (control). Cellular response was measured by assaying cell number, cell layer alkaline phosphatase specific-activity, and the production of osteocalcin, latent (L) TGFβ, and PGE2. Alkaline phosphatase activity was affected by surface roughness; as the surface became rougher, the cells showed a significant increase in alkaline phosphatase activity. Addition of 1α,25-(OH)2D3 to the cultures caused a dose-dependent stimulation of alkaline phosphatase activity that was synergistic with the effect caused by surface roughness alone. 1α,25-(OH)2D3 also caused a synergistic increase in osteocalcin production as well as local factor (LTGFβ and PGE2) production on the rougher CA, SB, and PS surfaces, but it had no effect on the production on smooth surfaces. The inhibitory effect of surface roughness on cell number was not affected by 1α,25-(OH)2D3 except on the SB surface. 1α,25-(OH)2D3 decreased cell number, increased alkaline phosphatase activity and osteocalcin production, and had no effect on LTGFβ or PGE2 production by MG63 cells grown on tissue culture polystyrene. These data suggest that bone cell response to systemic hormones is modified by surface roughness and that surface roughness increases the responsiveness of MG63 cells to 1α,25-(OH)2D3. They also suggest that the endocrine system is actively involved in normal bone healing around implants. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 39, 77-85, 1998.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Surface roughness modulates the local production of growth factors and cytokines by osteoblast-like MG-63 cells (1996)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 32 (1996), S. 55-63 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Titanium (Ti) surface roughness affects proliferation, differentiation, and matrix production of MG-63 osteoblast-like cells. Cytokines and growth factors produced in the milieu surrounding an implant may also be influenced by its surface, thereby modulating the healing process. This study examined the effect of surface roughness on the production of two factors known to have potent effects on bone, prostaglandin E2 (PGE2) and transforming growth factor β1 (TGF-β1). MG-63 cells were cultured on Ti disks of varying roughness. The surfaces were ranked from smoothest to roughest: electropolished (EP), pretreated with hydrofluoric acid-nitric acid (PT), fine sand-blasted, etched with HCl and H2SO4, and washed (EA), coarse sand-blasted, etched with HCl and H2SO4, and washed (CA), and Ti plasma-sprayed (TPS). Cells were cultured in 24-well polystyrene (plastic) dishes as controls and to determine when confluence was achieved. Media were collected and cell number determined 24 h postconfluence. PGE2 and TGF-β1 levels in the conditioned media were determined using commercial radioimmunoassay and enzyme-linked immunosorbent assay kits, respectively. There was an inverse relationship between cell number and Ti surface roughness. Total PGE2 content in the media of cultures grown on the three roughest surfaces (FA, CA, and TPS) was significantly increased 1.5-4.0 times over that found in media of cultures grown on plastic or smooth surfaces. When PGE2 production was expressed per cell number, CA and TPS cultures exhibited six- to eightfold increases compared to cultures on plastic and smooth surfaces. There was a direct relationship between TGF-β1 production and surface roughness, both in terms of total TGF-β1 per culture and when normalized for cell number. TGF-β1 production on rough surfaces (CA and TPS) was three to five times higher than on plastic. These studies indicate that substrate surface roughness affects cytokine and growth factor production by MG-63 cells, suggesting that surface roughness may modulate the activity of cells interacting with an implant, and thereby affect tissue healing and implant success. © 1996 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Bacteria/blood/material interactions. I. Injected and preseeded slime-forming Staphylococcus epidermidis in flowing blood with biomaterials (1995)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 29 (1995), S. 455-466 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Blood-material interactions were studied using in vitro recirculation with human blood, slime-forming Staphylococcus epidermidis, and cardiovascular materials. Staphylococcus epidermidis, under preseeded or injected conditions, adhered to nonsmooth materials and elevated plasma levels of fibrinopeptide A (FpA) and C3a in the presence of all materials. Increased white blood cell (WBC) and platelet adhesion and thrombospondin and platelet factor 4 (PF4) release were noted for respective materials in the presence of injected bacteria. Materials that adhered significant quantities of injected S. epidermidis exhibited low levels of adsorbed proteins. Materials with high levels of preseeded S. epidermidis showed high levels of adsorbed proteins. Adhesion of preseeded bacteria and blood plasma elevations of C3a and FpA were lowest on semicrystalline polymer substrates, intermediate on halogenated substrates, and highest on amorphous substrates. In the presence of injected bacteria, WBCs and platelets adhered at earlier recirculation times to amorphous substrates than to semicrystalline substrates. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820290405
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