D L Kreutzer

University of Connecticut, Storrs, CT, United States

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Publications (161)577.55 Total impact

  • Y W Novitsky, S B Orenstein, D L Kreutzer
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    ABSTRACT: Biologic mesh (BM) prostheses are increasingly utilized for hernia repairs. Modern BMs are not only derived from different tissue sources, but also undergo various proprietary processing steps-factors that likely impact host tissue responses and mesh performance. We aimed to compare histopathologic responses to various BMs after implantation in a mouse model. Five-mm samples of non-crosslinked [Strattice (ST)], and intentionally crosslinked [CollaMend (CM), Permacol (PC)] porcine-derived biologic meshes were implanted subcutaneously in C57BL/6 mice. 1, 4, 8, and 12 weeks post-implantation, meshes were assessed for inflammation, foreign body reaction (FBR), neocellularization, and collagen deposition using H&E and trichrome stains. All meshes induced early polymorphonuclear cell infiltration (highest in CM; lowest in ST) that resolved by 4 weeks. ST was associated with extensive macrophage presence at 12 weeks. Foreign body response was not seen in the ST group, but was present abundantly in the CM and PC groups, highest at 8 weeks. New peripheral collagen deposition was seen only in the ST group at 12 weeks. Collagen organization was highest in the ST group as well. Both CM and PC groups were associated with fibrous encapsulation and no evidence of integration or remodeling. Inflammation appears to be a common component of integration of all biologic meshes studied. Pronounced inflammatory responses as well as profound FBR likely lead to observed encapsulation and poor host integration of the crosslinked BMs. Overall, ST was associated with the lowest foreign body response and the highest degree of new collagen deposition and organization. These features may be key predictors for improved mesh performance during hernia repair.
    Hernia 12/2013; · 1.69 Impact Factor
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    ABSTRACT: Based on our in vitro study that demonstrated the adverse effects of blood clots on glucose sensor function, we hypothesized that in vivo local tissue hemorrhages, induced as a consequence of sensor implantation or sensor movement post-implantation, are responsible for unreliable readings or an unexplained loss of functionality shortly after implantation. To investigate this issue, we utilized real-time continuous monitoring of blood glucose levels in a mouse model. Direct injection of blood at the tissue site of sensor implantation was utilized to mimic sensor-induced local tissue hemorrhages. It was found that blood injections, proximal to the sensor, consistently caused lowered sensor glucose readings, designated temporary signal reduction, in vivo in our mouse model, while injections of plasma or saline did not have this effect. These results support our hypothesis that tissue hemorrhage and resulting blood clots near the sensor can result in lowered local blood glucose concentrations due to metabolism of glucose by the clot. The lowered local blood glucose concentration led to low glucose readings from the still functioning sensor that did not reflect the systemic glucose level.
    Journal of diabetes science and technology 01/2011; 5(3):583-95.
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    ABSTRACT: Mast cells (MCs) and their products (e.g., histamine, serotonin, heparin, prostaglandins, cytokines, etc.) play key roles in controlling local inflammation, wound healing, and foreign body reactions in vivo. Investigation of the role of MCs in mediating local tissue responses to synthetic hernia meshes has been very limited to date. We aimed to determine the effects of MCs/MC products in mice undergoing synthetic mesh implantation. Circular samples (5 mm) of heavyweight microporous polypropylene (Trelex), midweight microporous polypropylene (ProLite), lightweight macroporous polypropylene with poliglecaprone (Ultrapro), and 3-dimensional macroporous polyester (Parietex) meshes were implanted subcutaneously in C57BL/6 J mice with and without cromolyn (MC stabilizer/suppressant) treatment (50 mg/kg, daily IP). Two weeks post-implantation, all meshes were explanted and evaluated histologically using H&E and trichrome stains. Chronic inflammation was focused around individual mesh fibers; inter-fiber inflammation and fibrosis diminished as mesh porosity increased. MC accumulation was seen at the periphery of inflammatory reactions, and in association with mesh-induced fibrosis and neovascularization. Cromolyn treatment resulted in significantly decreased fibrotic responses to all four meshes and reduced inflammation induced by Trelex, ProLite, and Parietex meshes but not Ultrapro. We demonstrated that MCs play important roles in mesh-induced host tissue reactions. Blocking MC degranulation decreased early inflammation and fibrosis induced by most synthetic meshes in this study. Further evaluation and understanding of the role of MCs in mesh-induced tissue reactions will provide new therapeutic approaches to enhance the biocompatibility of surgical meshes and ultimately improve clinical outcomes in patients undergoing hernia repair with synthetic biomaterials.
    Hernia 10/2010; 14(5):511-6. · 1.69 Impact Factor
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    ABSTRACT: While porcine-based biologic meshes are increasingly used for hernia repair, little data exist on tissue responses to such products. Host foreign body reaction, local inflammation, and wound healing are principally controlled by monocytes/macrophages (M/MØs). Exaggerated activation of M/MØs may deleteriously influence mesh integration and remodeling. We hypothesized that common porcine meshes induce the differential activation of M/MØs in vitro. Samples of four acellular porcine-derived meshes, CollaMend (CM; C.R. Bard/Davol), Permacol (PC; TSL/Covidien), Strattice (ST; LifeCell), and Surgisis (SS; Cook Biotech), were exposed to mononuclear cells derived from the peripheral blood of six healthy subjects. Following a 7-day incubation period, supernatants were assayed for interleukin-1beta (IL-1beta), interleukin-6 (IL-6), interleukin-8 (IL-8), and vascular endothelial growth factor (VEGF) using a multiplex bead-based immunoassay system. The four groups were compared using analysis of variance (ANOVA) and Student's t-test. Each mesh type induced differential mononuclear cell activation in vitro. The mean IL-1beta expressions for CM (7,195 pg/ml) and PC (4,215 pg/ml) were significantly higher compared to ST and SS (123 and 998 pg/ml, respectively; P < 0.05). Similar trends were also seen for IL-6 (range 445-70,729 pg/ml), IL-8 (range 11,640-1,045,938 pg/ml), and VEGF (range 686-7,133 pg/ml). For the first time, we demonstrated that porcine meshes induce M/MØ activation in vitro. CM and PC (chemically crosslinked dermis) induced significantly higher cytokine expression compared to ST (non-crosslinked dermis) and SS (small intestine submucosa). These differences are likely related to proprietary processing methods and/or the extent of collagen crosslinking. Further understanding of immunologic effects of porcine-derived biologic meshes will not only allow for a comparison between existing products, but it may also lead to mesh modifications and improvement of their clinical performance.
    Hernia 02/2010; 14(4):401-7. · 1.69 Impact Factor
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    ABSTRACT: The importance of the interleukin (IL)-1 cytokine family in inflammation and immunity is well established as a result of extensive in vitro and in vivo studies. In fact, much of our understanding of the in vivo importance of interleukin-1beta (IL-1B) is the result of research utilizing transgenic mice, such as overexpression or deficiencies of the naturally occurring inhibitor of IL-1 known as interleukin-1 receptor antagonist (IL-1RA). For the present studies, we utilized these transgenic mice to determine the role of IL-1B in glucose sensor function in vivo. To investigate the role of IL-1B in glucose sensor function in vivo, we compared glucose sensor function in trans-genic mice that (1) overexpressed IL-1RA [B6.Cg-Tg(II1rn)1Dih/J] and (2) are deficient in IL-1RA (B6.129S-Il1rn(tm1Dih)/J), with mice that have normal levels of IL-1RA (C57BL/6). Our studies demonstrated that, during the first 7 days post-sensor implantation (PSI), mice deficient in IL-1RA had extensive inflammation and decreased sensor function when compared to normal or IL-1RA-overexpressing mice. These data directly support our hypothesis that the IL-1 family of cytokines and antagonists play a critical role in controlling tissue reactions and thereby sensor function in vivo during the first 7 days PSI.
    Journal of diabetes science and technology 01/2010; 4(5):1073-86.
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    ABSTRACT: BackgroundIn this article we present the design, construction and the first field tests of a new non-invasive blood glucose analyzer for mice using infrared radiation (IR) from a mouse tail. Thermal radiation from the blood vessels passes through a temperature gradient between the inner body and the ambient temperature outside.MethodThe temperature gradient causes an effective radiography of the colder skin layers resulting in an absorption spectrum of the fingerprint region in the infrared between 9 and 10 μm and thus allows estimation of glucose concentration. The realization of these measurements required an optical geometry designed for optimal detection of the tail radiation. The implementation of signal modulation and lock-in detection reduces the noise of the measurement.Results and conclusionThe analyzer delivers a signal proportional to glucose concentration. Continuous glucose measurements were done and compared to an implanted glucose sensor. The glucose concentrations and time-dependent changes in both methods are similar, validating the concept for the non-invasive blood glucose analyzer described in this paper.
    Sensors and Actuators B: Chemical. 11/2009;
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    ABSTRACT: Inflammation and wound healing play critical roles in the integration of biologic and biodegradable meshes (BMs) at hernia repair sites. Monocytes/macrophages (M/MØs) are key cells controlling inflammation and wound healing. These cells release inflammatory cytokines and growth factors such as interleukin (IL)-1beta, IL-6, IL-8, and vascular endothelial growth factor (VEGF) upon activation. Although BMs have been increasingly used in hernia repairs worldwide, to date, investigations of inflammatory responses to various BMs have been limited. Mesh samples of three acellular human dermis-derived biologic meshes (AlloDerm, AlloMax, FlexHD) and one biodegradable synthetic mesh (Bio-A) were placed in 96-well plates. Human peripheral blood mononuclear cells (PBMCs) were isolated from six healthy subjects, added to each well, and incubated for 7 days. Culture supernatants were assayed for IL-1beta, IL-6, IL-8, and VEGF levels using a multiplex bead-base immunoassay system (Bio-Plex). All four meshes induced cytokine expression from activated M/MØs to varying degrees in vitro. FlexHD induced significantly more IL-1beta (2,591 pg/ml) than AlloMax (517 pg/ml), AlloDerm (48 pg/ml), or Bio-A (28 pg/ml) (p < 0.001). AlloMax stimulated a significantly greater quantity of IL-6 (38,343 pg/ml) than FlexHD (19,317 pg/ml), Bio-A (191 pg/ml), or AlloDerm (103 pg/ml) (p < 0.05). Interleukin-8 and VEGF displayed trends similar to that of IL-6. There were no significant differences in cytokine production between AlloDerm and Bio-A. This study demonstrated that human macrophages are activated by human dermis-derived biologic and biodegradable meshes in vitro. A wide range of cytokine and growth factor induction was seen among the different mesh products. These differences in M/MØ activation may be related to the proprietary processing technologies of the studied meshes. The study results raise the possibility that these differences in M/MØ activation could indicate varying intensities of inflammation that control integration of different biologic meshes at the sites of hernia repair.
    Surgical Endoscopy 08/2009; 24(4):805-11. · 3.43 Impact Factor
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    ABSTRACT: Inflammation and wound healing play critical roles in the integration of biologic meshes (BMs) at sites of hernia repair. Monocytes/macrophages (M/MQs) are key cells involved in mesh integration. Interleukin-1beta (IL-1beta) is one of the major M/MQ-derived cytokines, and its expression is a reflection of the degree of M/MQ activation. We hypothesized that BMs induce M/MQ activation in vitro and that IL-1beta expression by M/MQ varies among various BMs. Acellular human dermis-derived BM samples (AlloDerm, AlloMax, FlexHD) were placed in 48-well plates and cultured with peripheral blood mononuclear cells (PBMCs) from three healthy human subjects for 7 d. The resulting supernatants were assayed for IL-1beta levels by enzyme-linked immunosorbent assay (ELISA), and the BMs were evaluated histologically. IL-1beta expression varied among donors as well as the BMs [AlloDerm (2.11-38.25pg/10(6) PBMCs); AlloMax (13.12-715.40pg/10(6) PBMCs); and FlexHD (116.69-665.40pg/10(6) PBMCs)]. Analysis of this data indicated that AlloMax and FlexHD induced significantly more M/MQ activation compared with AlloDerm (P<0.05). Histologic evaluation of the BMs indicated adherence of M/MQs on BM surface, however no degradation was detected. For the first time, we have demonstrated that M/MQs are activated to varying levels by human BMs in vitro. These differences may be related to BM processing technologies and/or the biologic variation between donors. Our results raise the possibility that these differences in M/MQ activation could result in varying intensity of inflammation and wound healing that control the integration of BMs at sites of hernia repair.
    Journal of Surgical Research 06/2009; 158(1):10-4. · 2.02 Impact Factor
  • Journal of Surgical Research - J SURG RES. 01/2009; 151(2):290-290.
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    ABSTRACT: Although tissue hemorrhages, with resulting blood clots, are associated with glucose sensor implantation, virtually nothing known is about the impact of red blood cells and red blood cell clots on sensor function in vitro or in vivo. In these studies, we tested the hypothesis that blood can directly interfere with glucose sensor function in vitro. To test this hypothesis, heparinized human whole blood (HWB) and nonheparinized human whole blood (WB) were obtained from normal individuals. Aliquots of HWB and WB samples were also fractionated into plasma, serum, and total leukocyte (TL) components. Resulting HWB, WB, and WB components were incubated in vitro with an amperometric glucose sensor for 24 hours at 37 degrees C. During incubation, blood glucose levels were determined periodically using a glucose monitor, and glucose sensor function (GSF) was monitored continuously as nanoampere output. Heparinized human whole blood had no significant effect on GSF in vitro, nor did TL, serum, or plasmaderived clots from WB. Sensors incubated with WB displayed a rapid signal loss associated with clot formation at 37 degrees C. The half-life was 0.8 +/- 0.2 hours (n = 16) for sensors incubated with WB compared to 3.2 +/- 0.5 (n = 12) for sensors incubated with HWB with a blood glucose level of approximately 100 mg/dl. These studies demonstrated that human whole blood interfered with GSF in vitro. These studies further demonstrated that this interference was related to blood clot formation, as HWB, serum, plasma-derived clots, or TL did not interfere with GSF in vitro in the same way that WB did. These in vitro studies supported the concept that the formation of blood clots at sites of glucose sensor implantation could have a negative impact on GSF in vivo.
    Journal of diabetes science and technology 11/2007; 1(6):842-9.
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    ABSTRACT: It is well established that the key to minimizing diabetes-associated complications, in both type 1 and type 2 diabetes, is tight regulation of blood glucose levels. Currently the major approach to regulating blood glucose levels in patients with diabetes relies on external blood glucose monitors. However, poor patient compliance usually results in limited insights into the dynamic range of blood glucose levels (i.e., hyperglycemia vs. hypoglycemia), and inadequate prediction and control of blood glucose levels in these patients. Implantable glucose sensors hold promise for controlling blood glucose levels, but currently these sensors have only limited in vivo life span. Recently we have developed an extremely robust murine model for implantable glucose sensors. In the present study, we have extended this model by developing a complete system for real-time continuous glucose monitoring in normal mice and mice with prediabetes and diabetes (type 1). These studies demonstrated that (1) glucose sensors can be implanted and maintained subcutaneously in the mice; (2) continuous glucose sensor data can be obtained for at least 5 days; and (3) subcutaneous blood glucose sensing paralleled blood glucose levels in normal mice and mice with prediabetes and diabetes. Subcutaneous blood glucose sensing also successfully tracked changes in blood glucose levels induced in the mice with diabetes by administration of oral glucose or insulin. These results mirror the results for subcutaneous blood glucose sensing seen in both normal subjects and patients with diabetes, and therefore validate both our continuous glucose monitoring system in the mouse, and the use of the mouse as a model for implantable glucose sensing in vivo.
    Diabetes Technology &amp Therapeutics 07/2006; 8(3):402-12. · 2.21 Impact Factor
  • Ulrike Klueh, David I Dorsky, Don L Kreutzer
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    ABSTRACT: The in vivo failure of implantable glucose sensors is thought to be largely the result of inflammation and fibrosis-induced vessel regression at sites of sensor implantation. To determine whether increased vessel density at sites of sensor implantation would enhance sensor function, cells genetically engineered to over-express the angiogenic factor (AF) vascular endothelial cell growth factor (VEGF) were incorporated into an ex ova chicken embryo chorioallantoic membrane (CAM)-glucose sensor model. The VEGF-producing cells were delivered to sites of glucose sensor implantation on the CAM using a tissue-interactive fibrin bio-hydrogel as a cell support and activation matrix. This VEGF-cell-fibrin system induced significant neovascularization surrounding the implanted sensor, and significantly enhanced the glucose sensor function in vivo. This model system, for the first time, provides the "proof of principle" that increasing vessel density at the sites of implantation can enhance glucose sensor function in vivo, and demonstrates the potential of gene transfer and tissue interactive fibrin bio-hydrogels in the development of successful implants.
    Biomaterials 05/2005; 26(10):1155-63. · 8.31 Impact Factor
  • U Klueh, D I Dorsky, D L Kreutzer
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    ABSTRACT: In the current study, we developed and validated a simple, rapid and safe in vivo model to test gene transfer and sensor function in vivo. Using the model, we tested the specific hypothesis that in vivo gene transfer of angiogenic factors at sites of biosensor implantation would induce neovascularization surrounding the sensor and thereby enhance biosensor function in vivo. As the in vivo site for testing of our gene transfer cell and biosensor function systems, the developing chorioallantoic membrane (CAM) of the embryo was utilized. Vascular endothelial cell growth factor (VEGF) was used as a prototype for angiogenic factor gene transfer. A helper-independent retroviral vector derived from Rous sarcoma virus (RSV), designated RCAS, was used for gene transfer of the murine VEGF (mVEGF) gene (mVEGF:RCAS) into the DF-1 chicken cell line (designated mVEGF:DF-1). Initially, the ability of VEGF:DF-1 cells to produce VEGF and RCAS viral vectors containing the mVEGF gene (mVEGF:RCAS) was validated in vitro and in vivo, as was the ability of the mVEGF:DF-1 cells to induce neovascularization in the ex ova CAM model. Using the system, we determined the ability of mVEGF:DF-1 cells to enhance acetaminophen sensor function in vivo, by inducing neovascularization at sites of sensor implantation in the ex ova CAM model. For these studies, acetaminophen sensors were placed on 8-day-old ex ova CAMs, followed by addition of media or cells (mVEGF:DF-1 cells or GFP:DF-1 cells) at the sites of biosensor implantation on the CAM. At 4 to 10 days after sensor placement, the biosensor function was determined by measuring sensor response to an intravenous injection of acetaminophen. Sensors implanted on CAMs with buffer or control cells (GFP:DF-1 cells) displayed no induced neovascularization around the sensor and had minimal/baseline sensor responses to intravenous acetaminophen injection (media, 133.33 +/- 27.64 nA; GFP:DF-1, 187.50 +/- 55.43 nA). Alternatively, the sensors implanted with mVEGF:DF-1 cells displayed massive neovascularization and equally massive sensor response to intravenous injection of acetaminophen (VEGF:DF-1, 1387.50 +/- 276.42 nA). These data clearly demonstrate that enhancing vessel density (i.e., neovascularization) around an implanted sensor dramatically enhances sensor function in vivo.
    Journal of Biomedical Materials Research Part A 01/2004; 67(4):1072-86. · 2.83 Impact Factor
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    ABSTRACT: One of the major obstacles in developing rationale strategies to control inflammation and fibrosis surrounding implants is the lack of a simple and inexpensive in vivo model to screen tissue reactions to various biomaterials and implants. To begin to fill this gap, we have developed an ex ova model of the chick embryo chorioallantoic membrane (CAM) for testing of tissue reaction to biomaterials and implants. For these studies, we evaluated tissue reactions (inflammation and fibrosis) to two commonly used biomaterials (nylon and silastic) grossly and histologically in the ex ova CAM. Nylon mesh was incorporated within the CAM tissue 4 days postplacement. After 8 days postplacement, the nylon mesh was totally incorporated into the CAM. Histologically, little or no inflammation was seen associated with the incorporated nylon mesh at any time point. In the case of silastic tubing, significant incorporation of the CAM was seen grossly by 1-2 days postplacement. Incorporation of the tubing continued at day 8 postplacement of the silastic tubing, with ingrowth of the CAM into the lumen of the tubing. Histological evaluation of CAMs indicated that no significant tissue reactions (inflammation or fibrosis) occurred in the CAM tissue surrounding the silastic tubing or in the CAM tissue and vasculature that had grown into the silastic tubing. To our knowledge, this report represents the first investigation of the usage of the ex ova CAM model, a shell-less chick embryo model (ex ova), as an in vivo model to test the tissue reactions to biomaterials and implants.
    Journal of Biomedical Materials Research Part A 01/2004; 67(3):838-43. · 2.83 Impact Factor
  • T I Valdes, U Klueh, D Kreutzer, F Moussy
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    ABSTRACT: A major problem with implantable sensors is their short in vivo lifetime, due to strong tissue reactions (i.e., inflammation and fibrosis) caused by the implant and the failure of sensor components. The tissue reactions to the sensor, the biocompatibility of components, and the function of the sensor must be evaluated by using in vivo models. Current methods of in vivo biosensor testing are time- and labor- intensive and expensive. In addition, the results often vary on the basis of the surgical skills of the investigator. The in ova chorioallantoic membrane (CAM) of the developing chicken embryo was previously developed in our laboratory as a novel in vivo system to test biomaterials. In this new article, we describe a novel approach for testing biosensors in vivo using the ex ova CAM model as an alternative to the traditional mammalian models. Fertilized chicken eggs were incubated for 3 days in ova and then transferred into a petri dish (ex ova) for further incubation at 37 degrees C and 80% humidity. After 1 week of incubation, acetaminophen biosensors, used as model sensors, were placed on top of the CAM and allowed to incorporate for 1 week. Biosensors were then tested for their sensitivity to acetaminophen. CAM venules were injected with 0.2 mL of a 3.6 mM acetaminophen solution. The current produced by the sensor reflected the change in blood acetaminophen levels. Sensors were also assessed by using gross and histological evaluations. We previously reported on the similarity of the tissue response of the CAM with the mammalian models. The low cost, simplicity, and possibility to continuously visualize the sensor test site through a cell culture dish make this animal model particularly attractive for the rapid in vivo screening of biosensors.
    Journal of Biomedical Materials Research Part A 11/2003; 67(1):215-23. · 2.83 Impact Factor
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    ABSTRACT: Previously, we have demonstrated the suitability of bacterial adhesin-related peptides, directly immobilized on polystyrene surfaces, to bind and orient fibronectin (FN). For these studies a method to bind the large protein FN in a desired orientation on a solid substratum was developed which utilizes a bacterial adhesin-related peptide (designated BRP-A), which is known to bind specifically to the NH3-terminus end of FN. Glass substrata was first coated with an amine-terminated silane, followed by streptavidin (SA), which was used as an intermediate tether to bind the biotinylated bacterial adhesin-related peptide. The BRP-A peptide, used for these studies was synthesized with a terminal biotin to assure irreversible coupling of the BRP-A to the streptavidin. The biotinylated BRP-A was next immobilized on the SA-silanated glass surfaces. 125I-FN was used to quantify the amount of FN binding to the (BRP-A):SA-silanated glass surface. Monoclonal antibodies, which react with specific epitopes at either the NH3- or -COOH-termini of FN, were used to quantify the binding and orientation of FN. The results of these studies indicated: (1) FN bound to the BRP-A:SA-silanated glass surface; and (2) the bound FN was oriented such that NH2-terminal region of FN was bound towards the glass surface and the COOH-terminus was oriented away from the glass surface. These studies demonstrate that small peptides can be used to specifically bind and orient large proteins such as FN on the surfaces.
    Biomaterials 11/2003; 24(22):3877-84. · 8.31 Impact Factor
  • U Klueh, J D Bryers, D L Kreutzer
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    ABSTRACT: Fibronectin (FN) is known to bind to bacteria via high affinity receptors on bacterial surfaces known as adhesins. The binding of bacteria to FN is thought to have a key role in foreign device associated infections. For example, previous studies have indicated that Staphylococcus aureus adhesins bind to the 29 kDa NH(3) terminus end of FN, and thereby promote bacteria adherence to surfaces. Recently, the peptide sequences within the S. aureus adhesin molecule that are responsible for FN binding have been identified. Based on these observations, we hypothesize that functional FN can be bound and specifically oriented on polystyrene surfaces using bacterial adhesin-related (BRP-A) peptide. We further hypothesize that monoclonal antibodies that react with specific epitopes on the FN can be used to quantify both FN binding and orientation on these surfaces. Based on this hypothesis, we initiated a systematic investigation of the binding and orientation of FN on polystyrene surfaces using BRP-A peptide. To test this hypothesis, the binding and orientation of the FN to immobilized BRP-A was quantified using (125)I-FN, and monoclonal antibodies. (125)I-FN was used to quantitate FN binding to peptide-coated polystyrene surfaces. The orientation of bound FN was demonstrated by the use of monoclonal antibodies, which are reactive with the amine (N) or carboxyl (C) termini of the FN. The results of our studies demonstrated that when the BRP-A peptide was used to bind FN to surfaces that: 1. functional FN was bound to the peptide; 2. anti-C terminus antibodies bound to the peptide FN; and 3. only limited binding of anti-N terminus antibodies to peptide-bound FN occurred. We believe that the data that indicate an enhanced binding of anti-C antibodies reactive to anti-N antibodies are a result of the FN binding in an oriented manner with the N termini of FN bound tightly to the BRP-A on the polystyrene surface.
    Journal of Biomedical Materials Research Part A 11/2003; 67(1):36-43. · 2.83 Impact Factor
  • R.V. Lalla, M.L. Tanzer, D.L. Kreutzer
    Archives of Oral Biology 01/2003; 48(4). · 1.55 Impact Factor
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    T I Valdes, D Kreutzer, F Moussy
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    ABSTRACT: Current in vivo models for testing biomaterials are time and labor intensive as well as expensive. This article describes a new approach for testing biomaterials in vivo using the chorioallantoic membrane (CAM) of the developing chicken embryo, as an alternative to the traditional mammalian models. Fertilized chicken eggs were incubated for 4 days, at which time a small window was cut in the shell of the egg. After 1 week of incubation, the CAM received several test materials, including the endotoxin LPS, a cotton thread and a Silastic tubing. One day and 1 week later, the tissue response to the test materials was assessed using gross, histological, and scanning electron microscope evaluations. The inflammatory response of the chorioallantoic membrane to biomaterials was fully characterized and found to be similar to that of the mammalian response and was also seen to vary according to test materials. We also found that the structure and geometry of the test materials greatly influenced the incorporation of the samples in the CAM. The similarity of the tissue response of the CAM with the mammalian models, plus the low cost, simplicity, and possibility to continuously visualize the test site through the shell window make this animal model particularly attractive for the rapid in vivo screening of biomaterials.
    Journal of Biomedical Materials Research 12/2002; 62(2):273-82.
  • T Hickey, D Kreutzer, D J Burgess, F Moussy
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    ABSTRACT: The purpose of this research effort was to evaluate in vivo a newly developed dexamethasone/PLGA microsphere system designed to suppress the inflammatory tissue response to an implanted device, in this case a biosensor. The microspheres were prepared using an oil/water (O/W) emulsion technique. The microsphere system was composed of drug-loaded microspheres (including newly formulated and predegraded microspheres) and free dexamethasone. The combination of the drug and drug-loaded microspheres provided burst release of dexamethasone followed by continuous release from days 2-14. Continuous release to at least 30 days was achieved by mixing predegraded and newly formulated microspheres. The ability of our mixed microsphere system to control tissue reactions to an implant then was tested in vivo using cotton thread sutures to induce inflammation subcutaneously in Sprague-Dawley rats. Two different in vivo studies were performed, the first to find the dosage level of dexamethasone that effectively would suppress the acute inflammatory reaction and the second to show how effective the dexamethasone delivered by PLGA microspheres was in suppressing chronic inflammatory response to an implant. The first in vivo study showed that 0.1 to 0.8 mg of dexamethasone at the site minimized the acute inflammatory reaction. The second in vivo study showed that our mixed microsphere system suppressed the inflammatory response to an implanted suture for at least 1 month. This study has proven the viability of microsphere delivery of an anti-inflammatory to control the inflammatory reaction at an implant site.
    Journal of Biomedical Materials Research 09/2002; 61(2):180-7.

Publication Stats

4k Citations
577.55 Total Impact Points

Institutions

  • 1987–2011
    • University of Connecticut
      • • Department of Medicine
      • • Department of Surgery
      • • School of Dental Medicine
      Storrs, CT, United States
  • 2009
    • Heidelberg University
      Tiffin, Ohio, United States
  • 2000
    • University of California, Los Angeles
      Los Angeles, California, United States
    • Connecticut Children's Medical Center
      Hartford, Connecticut, United States
  • 1996–1999
    • Kuwait University
      • Department of Medical Laboratory Science
      Kuwait, Muhafazat al `Asimah, Kuwait
    • University of Southern California
      • School of Dentistry
      Los Angeles, CA, United States
  • 1997
    • Johns Hopkins University
      • Department of Environmental Health Sciences
      Baltimore, MD, United States
  • 1987–1997
    • Hartford Hospital
      • Department of Pediatrics
      Hartford, Connecticut, United States
  • 1991
    • The Ohio State University
      • Department of Periodontology
      Columbus, OH, United States
  • 1990
    • Keio University
      • Department of Pediatrics
      Tokyo, Tokyo-to, Japan
  • 1984
    • Tufts University
      Georgia, United States