bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of pretreating porous webs on stromal fibroplasia in vivo
Authors: Trinkaus‐Randall V. , Banwatt R. , Wu Xin Yi , Leibowitz H. M. , Franzblau C. 
Published: May 2005

AbstractWe have previously demonstrated that keratocytes penetrate and deposit collagen after a porous web is inserted into interlamellar corneal pockets. In these studies our goal was to determine whether pretreatment of the porous discs were followed in vivo for a period of 42 days. The criteria we used to determine whether pretreatment affected wound healing were: collagen deposition, extent of fibroplasia, the synthetic rate of keratocytes within the disc, and lack of edema. Our results indicate that preseeding with stromal keratocytes enhanced the overall synthetic rate and specifically enhanced the amount of collage deposited within the web. © 1994 John Wiley & Sons, Inc.
Cellular uptake of titanium and vanadium from addition of salts or fretting corrosion in vitro
Authors: Maurer A. M. , Merritt K. , Brown S. A. 
Published: May 2005

AbstractThe use of titanium and titanium‐6% aluminum‐4% vanadium alloy for dental and orthopedic implants has increased in the last decade. The implants are presumed to be compatible because oseointegration, bony apposition, and cell attachment are known. However, the cellular association of titanium and vanadium have remained unknown. This study examined the uptake of salts or fretting corrosion products. Titanium was not observed to be toxic to the cells. Vanadium was toxic at levels greater than 10 μg/mL. The percentage of cellular association of titanium was shown to be about 10 times that of vanadium. The percentage of cellular association of either element was greater from fretting corrosion than from the addition of salts. The presence of vanadium did not affect the cellular uptake of titanium. The presence of titanium decreased the cell association of vanadium. © 1994 John Wiley & Sons, Inc.
Synthetic scleral reinforcement materials: I. Development and in vivo tissue biocompatibility response
Authors: Jacob‐LaBarre Jean T. , Assouline Michael , Byrd Thomas , McDonald Marguerite 
Published: May 2005

AbstractThe surgical treatment of pathological myopia involves the placement of a band cut from donor sclera around the back of the globe to provide support and to prevent elongation that leads to retinal detachment and blindness. In the search for a synthetic material that would overcome the disadvantages of the donor tissue band, we tested 11 types of band made from 14 polymers in rabbit eyes. Bands were cut from porous and solid materials, as well as porous patches affixed to the posterior surface. Criteria for suitability and biocompatibility included ease of placement and suturing, stable positioning, and absence of long‐term tissue response on a cellular level. Testing included evaluation by the surgeons performing the implantations, measurement of the distance between the band and the globe, determination of fibrous capsule thickness and amount of collagen deposition, and enumeration of macrophages accumulated at the band/capsule interface. Based on the results of these studies, two of the porous materials (expanded polytetrafluoroethylene and porous polyurethane fabric) and two of the composite materials (porous polyurethane fabric coated with polyacrylonitrile and silicone with microvilli cut into the posterior surface) were selected for further study. © 1994 John Wiley & Sons, Inc.
Morphologic variation in plasma‐sprayed hydroxyapatite‐bioactive glass composite coatings in Hank's solution
Authors: Lin J. H. Chern , Liu M. L. , Ju C. P. 
Published: May 2005

AbstractPure hydroxyapatite (HA), pure bioactive glass (BG), and a new series of (HA/BG) composite coatings were plasmasprayed onto a commercial Ti6A14V substrate. Changes in morphology and phases of these coatings after immersion in Hank's physiologic solution were investigated using XRD and SEM. Results indicated that the as‐sprayed BG coating has an essentially amorphous structure with a very rough surface. After 7 days of immersion, the BG surface started to dissolve, and weak XRD peaks of apatite started to develop. Small amounts of CaO, β‐TCP, Ca4P2O5, as well as a glassy film, were found on the as‐sprayed pure HA surface, most of which dissolved in 7 days. The XRD intensity of apatite in pure HA slowly increased with immersion time until, on the 10th day, the intensity started to drop, and 10 days later, the intensity rose again. This undiscovered “drop and rise” phenomenon was observed for the HA/BG composite coatings in an even more dramatic way. The presence of HA accelerates the dissolution of bioactive glass. © 1994 John Wiley & Sons, Inc.
Adhesion of lactobacilli to urinary catheters and diapers: Effect of surface properties
Authors: Reid Gregor , Lam Dominique , Bruce Andrew W. , van der Mei Henny C. , Busscher Henk J. 
Published: May 2005

AbstractThirteen strains of lactobacilli were tested for their ability to adhere to commercial devices used in the urinary tract. Although it appeared that the most hydrophilic organisms adhered in highest numbers, there was no significant correlation between water contact angle and adhesiveness to catheters. Five organisms tested were found to be highly adherent to Huggies commercial diapers. Loss in hydrophobicity upon serial culture of Lactobacillus fermentum B‐54 was not due to a proteinaceous S layer, although protein involvement per se cannot be ruled out. It was evident that, not only can members of the normal female urogenital flora adhere to commonly used commercial prostheses, but their ability to attach is related to hydrophilic as well as hydrophobic surface components. © 1994 John Wiley & Sons, Inc.
Complement activation on solid surfaces as determined by C3 deposition and hemolytic consumption
Authors: Liu Li , Elwing Hans 
Published: May 2005

AbstractComplement activation was investigated on hydrophilic and hydrophobic glass beads incubated in serum. Very little complement activation was detected with these surfaces, as indicated by a hemolytic assay and by measurement of the amount of iC3b appearing in the solution. However, preadsorption with IgG at the hydrophobic and hydrophilic beads resulted in complement activation on both surfaces. We also investigated dependent deposition of C3 at hydrophobic and hydrophilic silicon surfaces when the complement was activated. The chemistry of those surfaces is similar to the hydrophobic and hydrophilic beads. Ellipsometry, an optical method, was used for determination of the amounts of oraganic material deposited at the surface. C3 deposition was observed at the IgG precoated hydrophobic surface but not at the IgG‐coated hydrophilic surface. The absence of C3 deposition at the hydrophilic surface was probably due to reversible binding of IgG. However, precoating of the hydrophilic surface with a double layer of IgG and anti‐IgG resulted in C3 deposition also at the hydrophilic surface. The results illustrate that methods based on measuring deposition of C3 at surfaces, such as immunofluorescence or ellipsometry, cannot exclude surface‐associated complement activation that is probably due to reversible binding of the complement components of the activated molecule. On the other hand, it has previously been shown that determination of complement activation in solution with the use of a C3a assay cannot exclude surface‐associated activation due to immobilization of C3a at the surface.1 This methodologic question is an important issue because factors such as C3a and C5a act as soluble anaphylatoxins, whereas deposited factors such as C3 act as cellular receptors. © 1994 John Wiley & Sons, Inc.
Cyclic fatigue and fracture in pyrolytic carbon‐coated graphite mechanical heart‐valve prostheses: Role of small cracks in life prediction
Authors: Dauskardt R. H. , Ritchie R. O. , Takemoto J. K. , Brendzel A. M. 
Published: May 2005

AbstractA fracture‐mechanics based study has performed to characterize the fracture toughness and rates of cyclic fatiguecrack growth of incipient flaws in prosthetic heart‐valve components made of pyrolytic carbon‐coated graphite. Such data are required to predict the safe structural lifetime of mechanical heart‐valve prostheses using damagetolerant analysis. Unlike previous studies where fatiguecrack propagation data were obtained using through thickness, long cracks (∼2–20 mm long), growing in conventional (e.g., compact‐tension) samples, experiments were performed on physically small cracks (∼100–600 μm long), initiated on the surface of the pyrolytic‐carbon coating to simulate reality. Small‐crack toughness results were found to agree closely with those measured conventionally with long cracks. However, similar to well‐known observations in metal fatigue, it was found that based on the usual computations of the applied (far‐field) driving force in terms of the maximum stress intensity, Kmax, small fatigue cracks grew at rates that exceeded those of long cracks at the same applied stress intensity, and displayed a negative dependency on Kmax; moreover, they grew at applied stress intensities less than the fatigue threshold value, below which long cracks are presumed dormant. To resolve this apparent discrepancy, it is shown that long and small crack results can be normalized, provided growth rates are characterized in terms of the total (near‐tip) stress intensity (incorporating, for example, the effect of residual stress); with this achieved, in principle, either form of data can be used for life prediction of implant devices. Inspection of the long and small crack results reveals extensive scatter inherent in both forms of growth‐rate data for the pyrolytic‐carbon material. © 1994 John Wiley & Sons, Inc.
The delay method: A new surgical technique for enhancing the bone‐binding capability of HAP implants to bone surrounding implant cavity preparations
Authors: Ogiso Makoto , Yamashita Yasuo , Tabata Tsuneo , Ramonito Ree , Borgese Diego 
Published: May 2005

AbstractTo confirm the efficacy of a new apatite‐implantation technique, in vivo research was undertaken on 12 dogs. The project was designed to determine the time‐dependent effects on alveolar tissues surrounding implant cavity preparations without implantation in bone. In addition, a group of hydroxyapatite (HAP) implants was placed immediately after cavity preparation (conventional method). A second group was placed after a delay of 2 weeks (delay method). Hemorrhagic infiltration occurred within the cavity and into the surrounding fatty marrow, a phenomenon attributed to cavity preparation. Subsequent to absorption of infiltrated blood cells into the surrounding marrow, fibrous tissue was formed, followed by osseous formation initiated by the original bone. Formation of newly formed, thin trabeculae reached a peak at 14 days. Most of the original marrow near the cavity, where few trabeculae were originally present, was transformed into thin trabecular‐forming areas. In addition, sinusoidal capillaries and hematopoiesis were formed at the site. At 30 days, the number of new trabeculae and sinusoidal capillaries formed decreased, and adipose cells began to appear. These results indicate that tissue surrounding the prepared cavity was centrally activated at 14 days, and that this activation may be beneficial in the biologic ability of an apatite implant to advantageously affect bone binding and chemical bonding activity. It is concluded that bone formation was faster and wider around implants placed by the delay method than that surrounding conventionally placed implants. These results indicate that more efficient bone formation around implants was encouraged by bone activation stimulated during the 14 day delay period. © 1994 John Wiley & Sons, Inc.
Theoretical analysis of in vivo macrophage adhesion and foreign body giant cell formation on strained poly(etherurethane urea) elastomers
Authors: Kao Weiyuan John , Hiltner Anne , Anderson James M. , Lodoen G. A. 
Published: May 2005

AbstractQuantitative description of foreign body giant cell (FBGC) formation on poly(etherurethane urea) (PEUU) surfaces as a function of time can conceivably predict the effects of polymer characteristics on cellular responses in vivo. In the present study, the formation of FBGCs on strained and unstrained PEUUs was quantified with two parameters: the density of adherent macrophages present initially that participate in FBGC formation (do) and the rate constant for cell fusion (k); both kinetic parameters were used to calculate the time‐dependent FBGC density (dfc). Relationships were sought between results of the cellular analysis and the extent of environmental stress cracking (ESC), as characterized by scanning electron microscopy. Surface degradation was semiquantified with percent light transmittance.The materials used were: base PEUU, base PEUU with 1% Santowhite® antioxidant powder, base PEUU with 5% Methacrol 2133F® antifume agent, and base PEUU with both 1% Santowhite® and Methacrol 2138F®. A comparison of unstrained base PEUU with base PEUU strained to 400% elongation indicated that the rate of cell fusion, but not do and dfc, increased in the presence of strain. In all strained samples, additives that strongly affected the ESC also influenced FBGC kinetic parameters. Strained PEUU containing Santowhite® had the lowest do, the slowest rate of cell fusion, and lowest dfc, and the least incidence of ESC. The results suggest that the incidence of ESC in PEUU was decreased in the presence of Santowhite®, which also lowered the number of adherent macrophages participating in FBGC formation, the rate of FBGC formation and the subsequent FBGC density. These studies also indicate that strain in PEUUs does not directly modulate the adherent macrophage and FBGC density. Further studies are necessary to delineate the relationship between PEUU strain and adherent macrophage and FBGC activation, which leads to the exocytosis of degrading agents and the observed incidence of biodegradation. © 1994 John Wiley & Sons, Inc.
In vitro Plasma protein adsorption and kallikrein formation on 3‐mercaptopropionic acid, L‐cysteine and glutathione immobilized onto gold
Authors: Lestelius M. , Liedberg B. , Lundström I. , Tengvall P. 
Published: May 2005

Abstract3‐Mercaptopropionic acid (MPA), L‐cysteine (L‐cys), and glutathione (GSH) monolayers were immobilized onto gold and used in in vitro protein tests. The surfaces were characterized with ellipsometry, static contact angle measurements, atomic force microscopy, and Fourier transform in frared reflection absorption spectroscopy (FT‐IRAS). After incubations in human plasma and antibody solutions, the surface antisera binding patterns were determined with ellipsometry. Using serum instead of plasma, complement activation was studied in the same fashion. Activated coagulation Factor XII and Kallikrein formation on the surfaces and in the plasma were studied using a kallikreinspecific colorimetric assay. 3‐Mercaptopropionic acid indicated contact activation of coagulation but L‐cysteine did not. Glutathione displayed low deposition of plasma proteins, large deposition of proteins from serum, and did not promote kallikrein formation. None of the surfaces could be attributed complement activating properties, as determined by antibody deposition. The present study demonstrates that surface biology in complex model systems can be conveniently studied in vitro through systematic and well defined surface modifications. © 1994 John Wiley & Sons, Inc.
In vivo and electron microscopic studies of rat liver after intravenous injection of polyamino acid microspheres
Authors: Li C. , McCuskey P. , Kan Z. , Yang D. J. , Wright K. C. , Wailace S. 
Published: May 2005

AbstractIn vivo and electron microscopy were used to study the hepatocellular responses of rat livers to intravenously injected polymeric microspheres. Two microsphere preparation with different surface characteristics and degradability were used in this study. In vivo microscopy revealed that both poly(benzyl L‐glutamate) (PBLG) and poly(hydroxypropyl L‐glutamine) (PHPG) microspheres caused disturbance in the microcirculation of rat liver up to 2 months after injection. The observed changes included stagnant flow and adherence of white blood cells to the endothelial lining of venules and sinusoids. Kupffer cell (KC) activation following phagocytosis of microspheres was evidenced by the enlargement of KCs and increased number of KCs taking up fluorescent latex particles. Electron microscopy of rat livers revealed a wide range of hepatocellular injury associated with the administration of PBLG and PHPG microspheres. These results indicate that a small amount of remaining microspheres is sufficient to induce continuous disturbance to hepatic microcirculation and that particulate drug carriers should be designed to be rapidly degraded so that the return to normal liver function is possible. © 1994 John Wiley & Sons, Inc.
Joint resurfacing using allograft chondrocytes and synthetic biodegradable polymer scaffolds
Authors: Freed L. E. , Grande D. A. , Lingbin Z. , Emmanual J. , Marquis J. C. , Langer R. 
Published: May 2005

AbstractCartilage implants which could potentially be used to resurface damaged joints were created using rabbit articular chondrocytes and synthetic, biodegradable polymer scaffolds. Cells were serially passaged and then cultured in vivo on fibrous polyglycolic acid (PGA) scaffolds. Cell‐PGA constructs were implanted in vivo as allografts to repair 3‐mm diameter, full thickness defects in the knee joints of adult rabbits, and cartilage repair was assessed histologically over 6 months. In vitro, chondrocytes proliferated on PGA and regenerated cartilaginous matrix. Collagen and glycosaminoglycan (GAG) represented 20 to 8% of the implant dry weight (dw), respectively, at the time of in vivo implantation; the remainder was PGA and unspecified components. Implants based on passaged chondrocytes had 1.7‐times as much GAG and 2.6‐times as much collagen as those based on primary chondrocytes. In vivo, cartilaginous repair tissue was observed after implantation of PGA both with and without cultured chondrocytes. Six month repair was qualitatively better for cell‐PGA allografts than for PGA alone, with respect to: (1) surface smoothness, (2) columnar alignment of chondrocytes, (3) spatially uniform GAG distribution, (4) reconstitution of the subchondral plate, and (5) bonding of the repair tissue to the underlying bone. These pilot studies demonstrate that it is feasible to use cell‐polymer allografts for joint resurfacing in vivo. © 1994 John Wiley & Sons, Inc.
Magnetically directed poly(lactic acid) 90Y‐microspheres: Novel agents for targeted intracavitary radiotherapy
Authors: Häfeli Urs O. , Sweeney Siobhan M. , Beresford Beverly A. , Sim Edward H. , Macklis Roger M. 
Published: May 2005

AbstractHigh energy β‐emitting radioisotopes like Yttrium‐90 have a radiotoxic range of about one centimeter. For cancer treatment they must be brought near the tumor cells and kept there for as long as they are radioactive. We developed as carriers for the ionic form of 90Y a matrix‐type polymeric drug delivery system, poly(lactic acid) (PLA) microspheres. This radiopharmaceutical could be selectively delivered to the target site after incorporating 10% Fe3O4 (magnetite) which made the magnetic microspheres (MMS) responsive to an external magnetic field. Furthermore, MMS are biodegradable and slowly hydrolyze into physiologic lactic acid after the radioactivity is completely decayed. Previously prepared 10–40 μm MMS were radiochemically loaded to high specific activity with 90Y at a pH of 5.7. Stability studies showed that approximately 95% of added 90Y is retained within the PLA matrix after 28 days (>10 half‐lives) at 37°C in serum, and electron microscopy showed that the microspheres retained their characteristic morphologic appearance for the same time period. Cytotoxicity studies with SK‐N‐SH neuroblastoma cells growing in monolayer showed that the radiocytotoxicity of the microspheres could be directed magnetically to either kill or spare specific cell populations, thus making them of great interest for targeted intracavitary tumor therapy. We are currently optimizing this system for use in the treatment of neoplastic meningitis. © 1994 John Wiley & Sons, Inc.
Numerical analysis of extracellular fluid flow and chemical species transport around and within porous bioactive glass
Authors: García A. J. , Ducheyne P. 
Published: May 2005

AbstractModeling of the physical phenomena present at the biomaterial‐tissue interface provides a valuable tool for examining the underlying mechanisms which influence the overall behavior of the implant‐host system. Based on histological data from a previous implantation study (E. Schepers, M. De Clercq, P. Ducheyne, and R. Kempeneers, “Bioactive glass particulate materials as a filler for bone lesions,” J. Oral Rehab.; 18, 439–452, 1991, Ref. 1) which documented the differentiation of mesenchymal cells to cells expressing the osteoblastic phenotype in porous bioactive glass, a finite element momentum and mass transport model was constructed. In this analysis, the extracellular compositional variations and fluid flow conditions around and within porous bioactive glass granules were determined. Numerical simulations demonstrated that the interstitial fluid flow around these granules (300–360 μm) is viscosity dominated (low Reynolds number flow) and that the fluid inside the granules remains stagnant. This velocity field results in shear stresses proportional to the velocity gradient at the granule‐fluid interface outside the particles and no shear stresses inside the particles. A parametric study on the effect of interstitial fluid flow on chemical species (Na+, Ca+2, HPO4−2) transport outside the granules revealed three domains. At low velocities (0–0.1 μm/s), the transport of species is diffusion controlled. At intermediate velocities (1.0–10 μm/s), diffusion and convection contribute to the species transport. The concentration of chemical species is nearly uniform at high velocities (100–800 μm/s). For all three cases, the transport of chemical species within the granules is diffusion controlled. The differences in transport mechanisms and interstitial fluid flow conditions lead to variations in concentrations, reaction rates, and shear stresses between the inside and the outside of the glass granules. These differences may influence cellular migration, attachment, differention, and the overall response to these bioactive materials.
Interactions of human von Willebrand Factor with a hydrophobic self‐assembled monolayer studied by atomic force microscopy
Authors: Siedlecki Christopher A. , Eppell Steven J. , Marchant Roger E. 
Published: May 2005

AbstractHuman von Willebrand Factor (vWF) was studied by atomic force microscopy under physiologic buffer on a hydrophobic octadecyltrichlorosilane self‐assembled monolayer. The self‐assembled monolayer deposited on glass was sufficiently smooth (root mean square roughness = 0.25 ± 0.12 nm) to permit identification of adsorbed vWF. Adhesion of the protein to the hydrophobic substrate was sufficient to allow repeated scanning by the atomic force microscope probe, and images of vWF on a submolecular scale were obtained. The frictional force between the surface and the protein was sufficient to withstand an applied lateral force of 19 nN. This result shows that vWF experiences strong interaction with a hydrophobic surface in aqueous media. Statistical analysis of adsorbed vWF shows that the protein is composed of large globular domains with elliptical cross sections of average dimensions 56 ± 24 nm (major axis) 26 ± 19 nm (minor axis), and 2.8 ± 1.0 nm (height). Further analysis of the major axis dimension shows that the molecular chain of vWF contains two statistically different populations of domain size. However, no sequence order of the different population of domains within the individual molecule was found. On the basis of our analysis of the globular domains, we present a model describing the three‐dimensional structure of vWF protomer adsorbed on a hydrophobic surface in a physiologic solution. © 1994 John Wiley & Sons, Inc.