bluuebunny/crossref_metadata_2025_split huggingface dataset:
Contribution of vascular catheter material to the pathogenesis of infection: The enhanced risk of silicone in vivo
Authors: Sherertz Robert J. , Carruth William A. , Marosok Randy D. , Espeland Mark A. , Johnson Russ A. , Solomon Donald D. 
Published: December 2004

AbstractThere is currently very little information to suggest that polymer materials used to make vascular catheters differ in their risk of infection. A rabbit model of subcutaneous Staphylococcus aureus infection was used to determine the relative risk of infection associated with silicone, polyurethane, polyvinylchloride, and Teflon® catheters. Seven days after catheter implantation and inoculation with S. aureus, catheters were observed for gross purulence and quantitatively cultured. Silicone catheters were found to have a greater risk of grossly apparent infection (purulence) and a greater number of organisms removed from catheters by quantitative culture than the other three catheter materials (P < .01). The risk of infection associated with silicone catheters decreased (P < .05) if the S. aureus inoculation was delayed for 2 days or if the histology of the inflammatory response around the four catheter materials was evaluated at either 2 or 7 days after catheter insertion with or without S. aureus inoculation. Silicone catheters had greater associated inflammation (P < .05) with or without S. aureus inoculation. These results suggest that silicone catheter materials may have unique properties that increase the risk of infection after implantation. Further studies should be done to understand the mechanism(s) of these observations. © 1995 John Wiley & Sons, Inc.
Platelet activation by healing EPTFE grafts
Authors: Keith Ozaki C. , Contreras Mauricio , Phaneuf Matthew , Sheppeck Richard A. , Rutter Carolyn M. , Quist William C. , Logerfo Frank W. 
Published: December 2004

AbstractThe purpose of this study was to examine the effect of the in vivo maturing ePTFE graft surface on platelet activation. Ten canines were randomized to receive either a carotid to infrarenal aorta ePTFE graft or sham operation. Animals were sampled at specific time points up to 3 months post‐operatively. Whole blood platelet aggregometry (arachidonic acid, ADP, and collagen agonists) and ATP secretion (in response to arachidonic acid, ADP, collagen, and thrombin) were measured. Additionally, complete hematologic analysis and histology were performed. With time, graft animals showed significantly more decrease in platelet aggregation in response to ADP compared to sham animals (P = .023). The total amount of ATP per platelet was not different, as demonstrated by equivalent ATP release per platelet in response to thrombin. Over the first week, grafted dogs developed a decrease in systemic platelet count of 50% (P < .001) that persisted over the 3‐month follow‐up period. With time, overall regression model slopes of graft and sham platelet count data were not statistically different (P = .29). Histologically, the grafts demonstrated limited cellular ingrowth at both anstomoses, with fibrin matrix along the remainder of the blood‐biomaterial interface. These data suggest that, similar to Dacron, exposure to an ePTFE surface results in significant changes in platelet biology, and these platelet–ePTFE interactions persist even after the graft has formed a mature pseudointima. The pseudointima appears to be the primary determinant of the blood–biomaterial interaction. © 1995 John Wiley & Sons, Inc.
Control of contact activation on end‐point immobilized heparin: The role of antithrombin and the specific antithrombin‐binding sequence
Authors: Sanchez J. , Elgue G. , Riesenfeld J. , Olsson P. 
Published: December 2004

AbstractThe uptake and activation of FXII from blood plasma was studied in small‐diameter polyethylene tubing, surface‐modified by end‐point immobilization of heparin. Two preparations of heparin were used to modify the contact‐activating properties of the plastic tubing: unfractionated, functionally active heparin and low‐affinity heparin, lacking the specific antithrombin‐binding sequence and virtually devoid of anticoagulant activity. The uptakes of FXII on the two heparin surfaces were similar. No activated FXII could be demonstrated on the unfractionated heparin surface, whereas on the low‐affinity heparin surface nearly all FXII underwent spontaneous activation. The suppression of FXII activation on the unfractionated heparin surface was investigated by using plasma depleted of antithrombin, complement C1 esterase inhibitor, or both. The removal of antithrombin resulted in extensive activation of FXII, whereas the depletion of C1 esterase inhibitor had only a minor effect. Experiments with recalcified plasma showed rapid clot formation during exposure to the low‐affinity heparin surface. After depletion of antithrombin, but not complement C1 esterase inhibitor, the recalcified plasma clotted in contact with the unfractionated heparin surface as well. We conclude that antithrombin and the antithrombin‐binding sequence in the surface‐immobilized heparin are essential for the prevention of surface activation of FXII and triggering of the intrinsic coagulation system. © 1995 John Wiley & Sons, Inc.
Effect of self‐reinforced polyglycolide membranes on cortical bone: An experimental study on rats
Authors: Ashammakhi N. , Mäkelä E. A. , Vihtonen K. , Rokkanen P. , Törmälä P. 
Published: December 2004

AbstractA self‐reinforced polyglycolide (SR‐PGA) membrane has been developed recently by our research group and testing of it begun. To study the behavior of this membrane and its effect on cortical bone, 93 Wistar rats were operated on. SR‐PGA membrane was applied around the rats' femoral diaphyses, either over the periosteum or directly over the bone, after periosteal stripping. In a control group no membrane was applied, but the femoral periosteum was stripped away. The rats were sacrificed 1, 3, 6, 12, 24, and 30 weeks postoperatively. Radiology, histology, oxytetracycline fluorescence labeling, microradiography, and planimetry were used to determine the outcome. A fibrous tissue capsule had formed around and replaced the membrane. SR‐PGA membrane had a positive effect on new bone formation. Callus was frequently seen proximally and distally to the implant. Periosteal thickening occurred whether or not SR‐PGA membrane was used. PGA fibers decreased in number and diameter continuously until they vanished by 30 weeks. No infections or adverse reactions were encountered. Accordingly, SR‐PGA membrane is considered to be biocompatible and applicable in the treatment of cortical bone lesions such as comminuted fractures and defects. © 1995 John Wiley & Sons, Inc.
Augmentation of meniscal repairs with cyanoacrylate glue
Authors: Koukoubis Theodosios D. , Glisson Richard R. , Feagin John A. , Seaber Anthony V. , Vail Thomas Parker 
Published: December 2004

AbstractCyanoacrylate glues are biodegradable, bacteriostatic, hemostatic adhesives which have been used experimentally in surgical procedures on many tissues. This study evaluates the efficacy of cyanoacrylate glues used for in vitro bovine meniscus repair. Our hypothesis was that a local adhesive might improve fixation of meniscus tears reapproximated with suture, or obviate the need for suture. Three highviscosity flexible cyanoacrylate glues were tested and their tensile strengths compared to those of suture alone and suture augmented with glue. The flexible formulation enables the glue to deform with the meniscus during movement of the knee joint. Bovine meniscus tissue was used as the model to compare the tensile strength at the meniscus repair site using the 300 cps glue in combination with 3‐0 prolene suture, 300 cps cyanoacrylate glue alone, and suture alone. Twenty specimens were included in each repair group, and the peak load to failure was normalized for surface area and subjected to analysis of variance. Results of the analysis showed that the peak load to failure of the combination of cyanoacrylate glue plus suture was significantly higher than that of glue alone (P < .0001), but not significantly higher than that of suture alone (P = .18). However, in tissues repaired with suture, tissue separation at the tear site was noted almost immediately after distraction started, as a result of the elasticity of the suture. The combination of cyanoacrylate glue plus suture provided the maximum tensile strength before tissue separation. Because tissue separation may interfere with the meniscal healing process, glue used in combination with suture appears to offer some advantage mechanically. The cyanoacrylate formulations studied did not seem suitable for use without suture in meniscus repair. © 1995 John Wiley & Sons, Inc.
Development of surface photochemical modification method for micropatterning of cultured cells
Authors: Matsuda Takehisa , Sugawara Takashi 
Published: December 2004

AbstractThis article reports the development of micropatterning technology fo cultured cells by precise surface regional modification via photochemical fixation of phenyl azidoderivatized polymers on polymer surfaces. Photoreactive polymers prepared in this study included poly(N,N, ‐dimethylacrylamide‐co‐3‐azidostyrene), bis‐4‐azidobenzamide‐polyethylene glycol, and poly(styre‐co‐3‐azido‐styrene). The photochemical fixation of these photoreactive polymers consisted of three steps: (1) coating of a photoreactive polymer on a material surface, (2) ultraviolet irradiation through a photomask, and (3) removal of nonreacted polymer by a solvent. Electron spectroscopy for chemical analysis and water contact angle measurement were employed for surface characterization. Two different types of regionally modified surfaces were prepared; one was a hydrophilic polymer regionally fixed on a tissue culture dish and the other was a hydrophobic polymer regionally fixed on poly(vinyl alcohol) (PVA). Photochemical surface microfabrication permits μ‐order dimensional precision, which was verified by the micropatterned tissue formation of bovine aorta endothelial cells (ECs) when ECs were seeded on these surfaces. ECs adhered, spread, and confluently proliferated only on uncoated tissue culture dish surfaces or hydrophobic regions on PVA. Thus, the regionally differentiated cell adhesional regions were created by photo chemically driven surface microprocessing. © 1995 John Wiley & Sons, Inc.
Mechanical properties of the binary titanium‐zirconium alloys and their potential for biomedical materials
Authors: Kobayashi Equo , Matsumoto Shigeru , Doi Hisashi , Yoneyama Takayuki , Hamanaka Hitoshi 
Published: December 2004

AbstractMechanical properties of titanium‐zirconium binary alloys were investigated in order to reveal their possible use for new biomedical materials and to collect useful data for alloy design through a hardness test, a tensile test, and optical microscopy. The hardness of the alloy containing 50% zirconium was approximately 2.5 times as large as the hardness of pure titanium and pure zirconium. Tensile tests showed a similar tendency. No changes between hardness of as cast specimens and as homogenized specimens were observed, nor were changes in microstructures noted. Comparisons between the Ti‐6Al‐4V alloy and the Ti‐Zr‐6Al‐4V alloy indicated that a titanium‐zirconium alloy could provide a base material for a new biomedical alloy. From these results, it was concluded that new alloys for biomedical materials should be designed as titanium‐zirconium base alloys. © 1995 John Wiley & Sons, Inc.
Biodegradable sponges for hepatocyte transplantation
Authors: Mooney D. J. , Park S. , Kaufmann P. M. , Sano K. , McNamara K. , Vacanti J. P. , Langer R. 
Published: December 2004

AbstractLiver cell transplantation may provide a means to replace lost or deficient liver tissue, but devices capable of delivering hepatocytes to a desirable anatomic location and guiding the development of a new tissue from these cells and the host tissue are needed. We have investigated whether sponges fabricated from poly‐L‐lactic acid (PLA) infiltrated with polyvinyl alcohol (PVA) would meet these requirements. Highly porous sponges (porosity = 90–95%) were fabricated from PLA using a particulate leaching technique. To enable even and efficient cell seeding, the devices were infiltrated with the hydrophilic polymer polyvinyl alcohol (PVA). This reduced their contact angle with water from 79 to 23°, but did not inhibit the ability of hepatocytes to adhere to the polymer. Porous sponges of PLA infiltrated with PVA readily absorbed aqueous solutions into 98% of their pore volume, and could be evenly seeded with high densities (5 × 107 cells/mL) of hepatocytes. Hepatocyte‐seeded devices were implanted into the mesentery of laboratory rats, and 6 ± 2 × 105 of the hepatocytes engrafted per sponge. Fibrovascular tissue invaded through the devices' pores, leading to a composite tissue consisting of hepatocytes, blood vessels and fibrous tissue, and the polymer sponge. © 1995 John Wiley & Sons, Inc.
Effect of calcium phosphate (Ca‐P) coatings on trabecular bone response: A histological study
Authors: Caulier H. , van Der Waerden J. P. C. M. , Paquay Y. C. G. J. , Wolke J. G. C. , Kalk W. , Naert I. , Jansen J. A. 
Published: December 2004

AbstractThe trabecular bone response to noncoated and fluorapatite (FA), hydroxyapatite (HA), and hydroxyapatite heattreated (HAHT) plasma‐sprayed coated implants was investigated in a goat animal model. Forty‐eight cylindrical implants were inserted into the trabecular bone of the lateral and medial femoral condyles of twelve goats according to a split plot design. After an implantation period of twelve weeks, the bone‐implant interface was evaluated histologically. Quantitative histomorphometrical measurements demonstrated a significant difference in bone contact between implants inserted in the lateral and medial condyles. In addition, a significant difference in bone apposition was observed between the coated and the uncoated implants. Finally, all Ca‐P coatings showed reduction in coating thickness. Measurements revealed that FA and HAHT showed less reduction in coating thickness than HA coating. Despite the coating reduction, the bone remained in close contact with the implant surface. © 1995 John Wiley & Sons, Inc.
Field emission SEM comparison of four postfixation drying techniques for human dentin
Authors: Perdigao J. , Lambrechts P. , Van Meerbeek B. , Vanherle G. , Lopes A. L. B. 
Published: December 2004

AbstractCritical‐point drying (CPD) is generally considered essential for the preparation of biologic specimens for electron microscopy. Several attempts have been made to introduce alternative techniques. More recently, this problem has arisen in dentistry, because of the new developments in dentin bonding. The present study focuses on three alternative techniques to CPD: hexamethyldisilzane (HMDS) drying, Peldri II drying, and air drying. Twenty‐four dentin disks were obtained from noncarious extracted human molars by microtome sectioning parallel to the occlusal surface. The dentin surfaces were etched with polymer‐thickened, silica‐free, 10% phosphoric acid semigel, fixed, dehydrated, and dried with one of the four techniques. The specimens were observed in two perpendicular planes, showing dentinal tubules in longitudinal view and crosssection, using a field emission scanning electron microscope. The intertubular demineralized dentin zone was composed of three different successive layers, which did not substantially differ between CPD and Peldri II drying, but were more evident in HMDS‐dried specimens: first, an upper layer of denatured collagen and residual smear layer particles, with sectioned collagen fibrils and few open intertubular pores; second, an intermediate layer of closely packed cross‐sectioned collagen fibers; and third, a deeper layer with unfilled spaces, scattered hydroxyapatite crystals, and few collagen fibers. HMDS drying seemed to preserve better the collagen network and the microporosity of the demineralized dentin surface. Moreover, HMDS drying is easy to perform. The air‐drying method caused some artefacts, such as surface collapsing and thickening of the denatured collagen layer. © 1995 John Wiley & Sons, Inc.
Extracellular matrix interactions during the in vivo degradation of collagen membranes in the rat skin: Immunohistochemical distribution of collagen types IV, V, and VI
Authors: Romanos G. E. , Hotz S. T. K. , Schröter‐Kermani C. , Strub J. R. 
Published: December 2004

AbstractThe role of collagen implant material (CIM) in periodontology is of considerable interest to the clinical dentist because of the capacity of connective tissue (CT) regeneration and partial prevention of epithelial cell migration onto the root surface. The aim of this study was to demonstrate alterations of the CT matrix after the use of CIM in subcutaneous pockets in the rat skin. We used 15 rats in this study. After sedation, two subcutaneous pockets (2 cm in length) were surgically made in the animals' backs. Collagen membranes were implanted in one of the two pockets (test site). The other pocket served as control. Then, 4, 7, 14, 21, and 28 days after implantation, the animals were sacrificed and biopsies preserved for histologic and immunohistochemical examination. Incubation with antibodies against CT matrix components (collagen type IV, V, and VI) were used for immunostaining. Histologically, the CIM was migrated by inflammatory cells in the first 7 days. Newly formed fibroblasts and blood vessels (BV) were present 14 days postimplantation. Collagen type IV was localized in the basement membranes of the epithelium, BV, and nerves. An increase in the BV amount was demonstrated around (and later in) the implant material. Collagen type V was found in a filament pattern of distribution and was inserted into the implant after 4 weeks of healing. Collagen type VI showed a microfibrillar pattern of distribution with a delayed formation in the graft mass. The data showed the alterations of the matrix after implantation of collagen type I membranes in the rat skin. Furthermore, the CIM promoted fibroblast adhesion, cellular incorporation of its mass, and the formation of different collagen‐type fibers. © 1995 John Wiley & Sons, Inc.
Articular cartilage repair using allogeneic perichondrocyteseeded biodegradable porous polylactic acid (PLA): A tissue‐engineering study
Authors: Chu Constance R. , Coutts Richard D. , Yoshioka Makoto , Harwood Frederick L. , Monosov Anna Z. , Amiel David 
Published: December 2004

AbstractEfforts to expand treatment options for articular cartilage repair have increasingly focused on the implantation of cell‐polymer constructs. The purpose of this study is to determine the suitability of porous D,D‐L,L‐polylactic acid as a carrier for delivering repair cells obtained from rib perichondrium into full‐thickness articular cartilage defects. In vitro characterization of perichondrocyte‐polylactic acid composite grafts was combined with in vivo assessment of the early articular cartilage repair in a clinically relevant model. Using a fluorescent double‐stain protocol to visualize live and dead cells in situ, primary cells cultured from perichondrium were found to be capable of attaching to and surviving within a porous D,D‐L,L‐polylactic acid matrix. These perichondrocyte‐polylactic acid composite grafts were then implanted within osteochondral defects drilled into the left medial femoral condyles of 16 adult New Zealand white rabbits. Experimental animals were sacrificed 6 weeks after implantation and the repair tissue was evaluated grossly, histologically, and biochemically. Grossly, 96% (15/16) of the experimental animals demonstrated repairs consisting of a smooth, firm neocartilage which appeared similar in color and texture to the surrounding articular surface. Matrix staining for cartilaginous protein was seen surrounding chondrocyte‐like cells in the cartilage regions of the repair. Cellular alignment was found to be related to scaffold architecture. These results suggest that scaffolds composed of porous D,D‐L,L‐polylactic acid support the growth of cartilaginous repair tissue and are compatible with both in vitro and in vivo survival of chondrogenic cells. © 1995 John Wiley & Sons, Inc.
Rheological enhancement of mechanically activated α‐tricalcium phosphate cements
Authors: Gbureck U. , Spatz K. , Thull R. , Barralet J. E. 
Published: December 2004

AbstractMost biocements are two‐ or three‐component acid‐based systems with large differences in the component particle sizes, which occurs by virtue of the differing processing routes. This work aimed to improve injectability and strength of a single reactive component cement, that is, mechanically activated α‐tricalcium phosphate (TCP)‐based cement by adding 13–33 wt % of several fine‐particle‐sized (d50 of 0.5–1.1 μm) fillers [dicalcium phosphate anhydrous (DCPA), titanium dioxide (TiO2), and calcium carbonate] to the monomodal α‐TCP matrix (d50 = 9.8 μm). A high ζ‐potential was measured for all particles in trisodium citrate solution. The fraction of α‐TCP cement “injected” through an 800‐μm hypodermic needle was found to be only 35% at a powder‐to‐liquid ratio of 3.5 g/mL. In contrast, the use of fillers decreased cement viscosity to a point, where complete injectability could be obtained. Mechanistically, these additives disrupted α‐TCP particle packing yet decreased the interparticle spacing by a factor of ∼5.5 such that the electrostatic repulsion effect was enhanced. A strength improvement was found when DCPA and TiO2 were used as fillers despite the lower degree of conversion of these cements. Compressive strengths of precompacted cement samples increased from 70 MPa for unfilled α‐TCP cement to 140 (110) MPa for 23 wt % DCPA (or TiO2) fillers as a result of porosity reduction. Strength improvement for more clinically relevant uncompacted cements was achieved by higher powder‐to‐liquid ratio mixes for filled cements such that maximum strengths of 90 MPa were obtained for 23 wt % DCPA filler compared with 50 MPa for single‐component α‐TCP cement. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 73B: 1–6, 2005
New infusion device for trans‐tissue, sustained local delivery of anticancer agent to surgically resected tissue: Potential use for suppression of local recurrence of pancreatic cancer
Authors: Manabe Tatsuya , Okino Hidenobu , Maeyama Ryo , Mizumoto Kazuhiro , Tanaka Masao , Matsuda Takehisa 
Published: December 2004

AbstractLocal recurrence is a major cause of death of patients who have undergone resection for pancreatic cancer. To reduce the incidence of local recurrence, a new drug‐infusion device, which is fixed on resected tissues immediately after surgery, was devised for trans‐tissue, sustained local delivery. The drug‐infusion device proposed here has the following functions: tight adhesion of the device on resected tissues, sustained drug infusion to the tissue, drug reloading, and easy removal from the body after use. The fabricated prototype experimental device, described here, was a thin infusion pouch made of a thin elastomer film (segmented polyurethane), which is connected to an elastomeric tube for drug reloading. The suppressive effect of the device delivering the anticancer agent, gemcitabine (GEM), was examined using subcutaneous tumor‐bearing athymic mouse. A low‐dose, local sustained GEM delivery using the device significantly suppressed the tumor growth and regrowth after surgery. The preliminary model experimental result appears to provide a promising therapeutic procedure for increased survival rate of the patients undergoing surgery for pancreatic cancer. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 73B: 203–207, 2005